Endogenous guinea pig virus: equability of virus-specific DNA in normal, leukemic, and virus-producing cells. The kinetics of hybrid formation between the RNA of BrdU-activated endogenous guinea pig virus and the DNA of leukemic, normal, or BrdU-activated guinea pig cells were measured by the technique of RNA.DNA hybridization in DNA excess. The results suggest that virus-specific sequences representing some 60-70% of the viral genome are unique (2-3 copies per haploid cell genome), while the remainder (30-40%) are reiterated (147 copies), and that the reiterated virus-specific DNA may be composed of more than one species, each having a different reiteration frequency. No difference was found in the quantity of viral DNA sequences contained in normal, leukemic, or bromodeoxyuridine-activated guinea pig cells. These data are considerably different from those reported for exogenous (infectious) oncornaviruses, where cells infected or transformed by exogenous RNA tumor viruses have been shown to contain increased amounts of virus-specific DNA. The data reported here are consistent with the contention that preexisting viral genes are activated by bromodeoxyuridine treatment. Results of hybridization experiments done at different DNA/RNA ratios suggest that although the virus-specific DNA is partly unique and partly reiterated, the viral RNA does not contain any detectable internal reiteration. Total mass of the viral RNA sequences is around 0.7 to 1 x 10(7) daltons.


Purification and properties of two RNA polymerases from Physarum polycephalum. Two RNA polymerases have been purified from the slime mold Physarum polycephalum, one sensitive and one resistant to alpha-amanitin. Both enzymes are more active with denatured DNA than native DNA as a template and prefer Mn(++) rather than Mg(++) as a divalent cation. The alpha-amanitin-sensitive enzyme shows maximum activity at 0.15 M KCl, whereas the resistant enzyme is most active at very low ionic strength. Analysis of the resistant enzyme on polyacrylamide gels containing sodium dodecyl sulfate shows two subunits present in a 1:1 ratio with molecular weights of 205,000 and 125,000.


Transfer of newly synthesized proteins from Schwann cells to the squid giant axon. The squid giant axon is presented as a model for the study of macromolecular interaction between cells in the nervous system. When the isolated giant axon was incubated in sea water containing [(3)H]leucine for 0.5-5 hr, newly synthesized proteins appeared in the sheath and axoplasm as demonstrated by: (i) radioautography, (ii) separation of the sheath and axoplasm by extrusion, and (iii) perfusion of electrically excitable axons. The absence of ribosomal RNA in the axoplasm [Lasek, R. J. et al. (1973) Nature 244, 162-165] coupled with other evidence indicates that the labeled proteins that are found in the axoplasm originate in the Schwann cells surrounding the axon. Approximately 50% of the newly synthesized Schwann cell proteins are transferred to the giant axon. These transferred proteins are soluble for the most part and range in molecular size from 12,000 to greater than 200,000 daltons. It is suggested that proteins transferred from the Schwann cell to the axon have a regulatory role in neuronal function.


In vitro properties of leukocyte dialysates containing transfer factor. The chief impediment to the precise biochemical identification of transfer factor and its mechanism of action has been the lack of a reproducible in vitro assay. We now report on a method by which dialysates containing transfer factor of proven in vivo potency can convert nonimmune lymphocytes to immune responsiveness in vitro, as reflected by antigen-triggered lymphocyte proliferation. However, "water-dialyzed transfer factor" (TF(D)) prepared for in vivo use by the conventional method of dialysis against large volumes of water exhibits diminished activity in vitro and is frequently toxic to lymphocyte cultures. This problem can be avoided by dialysis of transfer factor into tissue culture medium. When this precaution is taken, such "media-dialyzed transfer factor" (TF(DM)) causes nonimmune lymphocytes to respond to antigen by an increment of thymidine incorporation that ranges from 2 to 25 times that of such cells cultured with antigen alone. This response is generally observed only in the presence of those antigens to which the TF(DM) donor expresses delayed cutaneous reactivity and is distinguishable from nonspecific adjuvant effects.


Purification and partial characterization of a glycoprotein sexual inducer from Volvox carteri. A method is described for the isolation and purification of the sexual inducer produced by male colonies of the colonial green alga Volvox carteri. The procedure yields a highly purified preparation of the inducer. The biologically active principal is demonstrated to be a glycoprotein with a molecular weight of 32,000.


Adriamycin and daunorubicin inhibition of mutant T4 DNA polymerases. The anticancer drugs, adriamycin and daunorubicin, as well as two other DNA reagents, ethidium bromide and 9-aminoacridine, all exert a differential inhibitory effect on nucleotide incorporation for purified DNA polymerases induced by mutant and wild-type bacteriophage T4. When compared with DNA polymerase of wild-type phage, antimutator enzymes are inhibited to a far greater extent and mutator enzymes to a lesser extent. In contrast, the polymerase-associated 3'-exonuclease activities of wild type and mutants are also inhibited by the compounds but nondifferentially.


In vivo release of glycoprotein I from the Ha subline of TA3 murine tumor into ascites fluid and serum. Previous studies have demonstrated that a unique glycoprotein can be cleaved by trypsin from the plasma membrane of the Ha, but not the St, subline of the TA(3) murine mammary adenocarcinoma. Using an automated quantitative method for measurement of trypsincleaved fragments (glycoprotein fraction I) by inhibition of Vicia graminea lectin hemagglutination, we find evidence that glycoprotein fraction I-like molecules appear in the ascites fluid and serum of the Ha-bearing, but not the St-bearing, syngeneic mice. These molecules were shown by gel filtration to be larger than the trypsincleaved glycoprotein fraction I but have a carbohydrate composition very similar to glycoprotein fraction I. It is likely that these ascites and serum glycoproteins have been released in vivo from the membranes of the viable Ha tumor cells. In view of the ability of the Ha, but not the St, cells to grow in allogeneic recipients, it is possible that these circulating membrane-derived molecules may be playing a blocking role in the immune response to the tumor.


Photophosphorylation in Halobacterium halobium. Halobacterium halobium cells grown under semi-anaerobic conditions convert part of their cell membrane into "purple membrane" which contains a rhodopsin-like protein, bacteriorhodopsin. Under anaerobic conditions in the dark the ATP content of such cells decreases sharply. Either light or oxygen restores the ATP content to the original level. The light effect is mediated by the purple membrane. Inhibitors of the respiratory chain abolish the oxygen response but do not affect the light response. Uncouplers, which function as proton translocators, abolish the light response. These results indicate that the purple membrane functions as a lightdriven proton pump and the cells use the resulting chemiosmotic gradient for ATP synthesis.


Pregelation aggregation of sickle cell hemoglobin. Quasi-elastic light scattering was used to detect the initial stage of aggregation of hemoglobin S solutions. Aggregation of a hemolysate upon deoxygenation was found to occur at concentrations above 11 g/dl, but purified hemoglobin S solutions showed evidence of aggregation only for concentrations greater than 14 g/dl. A transition from a nonaggregated to an aggregated state was observed when the oxygen pressure in solution was reduced below a critical value. The total intensity of the scattered light during the early stages of aggregation was found to increase linearly with time. This result is consistent with a linear association process in which any size aggregate can combine with any other size aggregate.


The effect of pressure on the molecular complex of isoalloxazine and adenine. The effect of pressure to 10 kilobars on the fluorescence characteristics of flavin mononucleotide (FMN), flavin-adenine dinucleotide (FAD), and on complexes of FMN with adenylic acid (AMP), and with I(-) has been studied. The properties measured include peak location, fluorescence yield, and lifetime. From these results the equilibrium constant K and the rate constant k(+) (*) for complex formation were evaluated as a function of pressure. The pressure dependence of these coefficients shows that the volume of the system decreases upon complex formation and that there is an expansion upon formation of the activated complex (DeltaVdouble dagger is positive). The implications of these results for protein denaturation are mentioned.


A restriction point for control of normal animal cell proliferation. This paper provides evidence that normal animal cells possess a unique regulatory mechanism to shift them between proliferative and quiescent states. Cells cease to increase in number under a diversity of suboptimal nutritional conditions, whereas a uniformity of metabolic changes follows these nutritional shifts. Evidence is given here that cells are put into the same quiescent state by each of these diverse blocks to proliferation and that cells escape at the same point in G(1) of the cell cycle when nutrition is restored. The name restriction point is proposed for the specific time in the cell cycle at which this critical release event occurs. The restriction point control is proposed to permit normal cells to retain viability by a shift to a minimal metabolism upon differentiation in vivo and in vitro when conditions are suboptimal for growth. Malignant cells are proposed to have lost their restriction point control. Hence, under very adverse conditions, as in the presence of antitumor agents, they stop randomly in their division cycle and die.


The synthesis of human placental lactogen by ribosomes derived from human placenta. In a very active cell-free system containing polysomes derived from human placenta and a cell-sap fraction prepared from ascites tumor cells, the synthesis of the hormone human placental lactogen (HPL) was detected. The identification was based on the following: (a) The in vitro synthesized protein labeled with [(35)S]methionine migrated at the same rate as authentic HPL on sodium dodecyl sulfate-polyacrylamide gels and (b) tryptic fingerprint analysis of the labeled protein yielded peptides having the same mobilities as seen with the same analysis of purified HPL. The amount of HPL synthesized in a cell-free system containing polysomes derived from term placenta was about 10% of the total proteins synthesized and in a comparable system containing first trimester ribosomes the level of synthesis was about 5%. These data suggest the potential for quantitating the HPL mRNA activity as a function of the period of gestation and for isolating the mRNA itself.


Structure of an iron(II) dioxygen complex; a model for oxygen carrying hemeproteins. The preliminary structural characterization of a reversible ferrous dioxygen complex is reported. Mono(N-methyl imidazole) (dioxygen) meso-tetra (alpha,alpha,alpha,alpha-o-pivalamidephenyl) porphinatorino(II), [Fe(O(2))-(N-Me imid) (alpha,alpha,alpha,alpha-TpivPP)], 1, isolated from toluene solution, crystallizes in the monoclinic system with four molecules in a unit cell of dimensions a = 18.690 (3), b = 19.514 (3), c = 18.638 (3) A, and beta = 91.00 (1) degrees . R = 0.15 for 841 reflections having F(2) > 3sigma (F(2)). The complex 1 has four pivalamido groups on one side of the porphyrin forming a hydrophobic pocket of 5.4-A depth which encloses coordinated dioxygen. The dioxygen is coordinated "end-on," with a bent Fe-O-O bond. The Fe-O-O plane bisects an N-Fe-N right angle of the equatorial iron porphyrin plane and is four way statistically disordered. In addition there is a crystallographic 2-fold axis through iron, coordinated oxygen, and nitrogen of the axially bound N-methyl imidazole. Thus there are two types of coordinated dioxygen with the Fe-O-O plane either parallel or perpendicular to the trans axial imidazole plane. Corresponding values for the Fe-O-O bond angles are 135-(4) degrees and 137(4) degrees and for the O-O bond lengths are 1.23 (0.08) and 1.26 (0.08) A, with a dihedral angle of 90 degrees between alternative orientations of the Fe-O-O plane. The Fe-O distance is 1.75 (0.02) A and Fe-N (imidazole) is 2.07 (0.02) A, suggesting multiple bond character in the Fe-O moiety. The similarity of the Mössbauer spectrum of the model complex, 1, with oxyhemoglobin indicates that 1 may be a good model for oxygen binding in the oxygen transport hemeproteins.


Sexual morphogenesis in Achlya: ultrastructural basis for the hormonal induction of antheridial hyphae. Male strains of the water mold Achlya ambisexualis produce antheridial hyphae in response to the steroid hormone antheridiol. The antheridial hypha is postulated to be initiated through a localized wall softening with the enzyme cellulase. Freeze-etch studies of hormone-treated hyphae were conducted to determine if aggregates of vesicles are induced at the location of new antheridial hyphae. Localized aggregates of vesicles were found in conjunction with areas of wall thinning. These data suggest that the processes of vesiculation and secretion provide a mechanism for concentration of cellulase at the site of initiation of antheridial hyphae.


Synthesis of complementary strands of heterologous RNAs with Qbeta replicase. Qbeta replicase, in the presence of Mn(++), can use various RNAs as templates for synthesis of full-length RNA products and can also use Qbeta plus-strand RNA as template in the absence of host factors.


Localization of acetylcholine receptor by 125I-labeled alpha-bungarotoxin binding at mouse motor endplates. Exposed sternomastoid muscles of anaesthetized mice were bathed in (125)I-labeled alpha-bungarotoxin until all neurally evoked muscle contractions were eliminated. The distribution of label was then determined by electron microscope autoradiography. It was found that the label was localized at the top of the junctional folds, i.e., at the postjunctional membrane nearest the axon. Since the alpha-bungarotoxin had fully eliminated the physiological muscle response, these results indicate that the active acetylcholine receptor occupies a limited area of the junctional folds and is not distributed uniformly throughout this membrane. Specialized membrane densities seem to coincide with the labeled regions.


Kinetic properties of the isoenzymes of human creatine phosphokinase. Studies of the three human creatine phosphokinase (EC 2.7.3.2) isoenzymes, MM, MB, and BB, show that important differences exist in substrate dependency of the reaction rates. A method was developed to study these properties in which the ATP formed in the reverse reaction was measured by means of firefly luciferase. With substrate conditions at which the isoenzymes showed substantial differences in activity the method could be used for the detection of changes in the isoenzyme pattern of the serum of patients with an acute myocardial infarction. The MB isoenzyme appearing in this condition could be detected quantitatively.


Modulation of the activity of an avian gene transferred into a mammalian cell by cell fusion. Mouse A9 cells, deficient in hypoxanthine phosphoribosyltransferase (EC 2.4.2.8), were fused with normal chick erythrocytes and selected in hypoxanthine-aminopterin-thymidine medium for cells with hypoxanthine phosphoribosyltransferase activity. Recovered hybrid cells produced the chick hypoxanthine phosphoribosyltransferase exclusively, as demonstrated by electrophoretic mobility and immunoprecipitation tests, even though no chick chromosomes or chick cell-surface antigens could be identified in the hybrids. Surprisingly, the expression of the chick hypoxanthine phosphoribosyl-transferase activity in the mouse/chick hybrids required the presence of aminopterin in the growth medium; in its absence, enzyme synthesis decreased markedly. Because of the rapid and reversible modulation of hypoxanthine phosphoribosyltransferase activity, the hybrid cells could proliferate equally well in media containing hypoxanthine-aminopterin-thymidine or 8-azaguanine. Cellular selection was definitely ruled out as a possible cause. These results confirm previous reports that specific genetic information can be selectively transferred from one cell to another of a distant species. Furthermore, they demonstrate that an avian gene, whose activity is normally expressed constitutively, can become facultative when integrated into a mammalian cell. This seems to be the first instance where heterologous gene activity has been shown to be reversibly modulated in hybrid cells.


The three dimensional structure of a combining region-ligand complex of immunoglobulin NEW at 3.5-A resolution. IgG New binds ligands such as orceine, menadione, and uridine with a low affinity (K(0) about 1 x 10(3) liter/mol) and a gamma-hydroxy derivative of vitamin K(1) with a higher affinity (K(0) = 1.7 x 10(5) liter/mol). Binding studies indicate that both the 2-methylnaphthoquinone rings and the phytyl tail of the vitamin K(1) hapten contribute to the total binding energy. The binding of these ligands in the crystalline state has been investigated by difference Fourier maps of Fab' New-ligand complexes at 6-A resolution. A 3.5-A resolution difference Fourier map obtained for the gamma-hydroxy derivative of the vitamin K(1)-Fab' complex shows that this hapten is bound in a shallow groove or crevice between the light and the heavy chains, in close proximity to the polypeptide segments containing the hypervariable regions. At least 12 amino-acid residues from both the light and the heavy chains appear to be in close contact with the ligand. No major conformational changes were detected in the Fab' fragment after ligand binding.


Protein fusion: a novel reaction in bacteriophage lambda head assembly. Parts of two phage-coded head proteins, pE and pC, become fused during bacteriophage lambda head assembly. pE is the main structural component of lambda heads and pC is a minor head protein that is not found as such in mature heads. The bond joining the two proteins appears to be covalent and is not a disulfide bond. Only a specific subset of the sequences of each protein is found in the fusion products, and these sequences are found in the products in equimolar amounts. Two nearly identical fusion products; X1 and X2, are detected; X2 is slightly smaller than X1 and appears to be a proteolytic cleavage product of X1. The fusion reaction probably takes place on a nascent head structure.


In vitro synthesis of mouse neuroblastoma tubulin. Polyribosomes were isolated from a clonal line of mouse neuroblastoma grown in culture. In a heterologous in vitro system containing rat brain components, these polyribosomes were shown to direct the synthesis of neuroblastoma tubulin. Identification of the tubulin synthesized in vitro was achieved by coelectrophoresis with native neuroblastoma tubulin on sodium dodecyl sulfate polyacrylamide gels, immunoprecipitation, and demonstration of specific aggregation. Tubulin accounted for 2% of the total proteins synthesized. This in vitro protein synthesizing system offers a model for studying possible translational control mechanisms regulating the synthesis of proteins involved in nerve cell function.


Human tumors detected by nuclear magnetic resonance. Measurements of the water proton spinlattice relaxation (T(1)) in 106 human tumors confirms earlier results with animals [Damadian, R. (1971) Science 171, 1151-1153]. T(1) of all the tumors studied were significantly longer than T(1) of the corresponding normal tissues. Mean standard error and range were reported for T(1) of every human organ and for all the tumor groups studied. The technique is now ready for use by pathologists as an adjunct to present methods of diagnosing malignancy.


The synthesis and stability of cytoplasmic messenger RNA during myoblast differentiation in culture. The synthesis of poly(A)-containing cytoplasmic RNA was examined in primary myoblast cultures prepared from skeletal muscle of fetal calves. After a period of cell division, these cells undergo fusion, with concomitant appearance of acetylcholine receptor and subsequent myosin synthesis. In the dividing myoblast there is a high level of messenger RNA synthesis, including a 26S RNA, the size of a putative messenger for the large subunit of myosin. In the transition period prior to fusion, there are quantitative changes in RNA synthesis. At this time, there is a pronounced production of 26S RNA, which diminishes during fusion. The possibility that 26S RNA is accumulated in the dividing myoblast was investigated by chase experiments. At fusion, there is a marked increase in the half-lives of a number of messenger RNA species, including 26 S, which increases from about 10 hr in the dividing cell to a value of more than 50 hr. The identity of the more rapidly turning over 26 S in the myoblasts, compared to that of the 26 S at fusion, was examined in terms of polysomal distribution, migration on gels, and hybridization with complementary DNA for the myosin message. The results of these analyses suggest that the 26S species are identical. Thus, it would appear that in a predetermined cell like the myoblast, the transition to the differentiated state of myotube that is synthesizing muscle specific proteins is effected by the stabilization of messenger already being actively transcribed: terminal differentiation, with respect to myosin synthesis, is preceded by the stabilization of 26S RNA.


Reconstitution of a chemically excitable membrane. Membrane fragments rich in cholinergic (nicotinic) receptor sites, purified from homogenates of Torpedo marmorata electric organ, are dissolved in high concentrations of Na cholate and Tris buffer in the presence of Na ethylenediaminetetraacetate, without loss of the ability to bind Naja nigricollis [(3)H]alpha-toxin. After extensive dialysis to remove cholate, the solution is supplemented with crude lipids extracted from native membrane fragments and MgCl(2)-CaCl(2) added dropwise to the mixture as a concentrated solution. The reconstituted membranes obtained retain (22)Na(+). Release of Na from these microsacs increases in the presence of carbamylcholine and the alpha-toxin from N. nigricollis blocks this effect.


Light-dependent redistribution of ions in suspensions of chloroplast thylakoid membranes. Ion movements associated with the pH rise that is observed upon illumination of thylakoid suspensions at low pH have been studied by a multiparameter technique. Light-dependent, dark-reversible fluxes of H(+), Cl(-), Na(+), K(+) and divalent cations were monitored, together with simultaneous changes in the optical density of the suspension. Extensive uptake of Cl(-) and efflux of Mg(2+) accompany the apparent inward movement of H(+) in the light. Only minor efflux of K(+) is seen and Na(+) appears immobile. The Cl(-) and Mg(2+) fluxes together compensate for most of the charge transferred as H(+), contributing respectively about 49% and 43% on an equivalent basis. The ratio of Cl(-) influx to Mg(2+) efflux is variable, but usually >1.0. The Mg(2+) flux can be supplanted by (1) K(+) flux, if the K(+)/Mg(2+) activity ratio in the suspension is high, and (2) Ca(2+) flux, if the thylakoids are equilibrated with suspending media containing Ca(2+). The affinity of the divalentcation-binding sites, or carrier mechanism, is greater for Ca(2+) than for Mg(2+). Schemes can be drawn up to account for the observed ion movements on the basis of either a chemical or a chemiosmotic mechanism for energy transduction in chloroplasts. In intact chloroplasts, light-dependent control of Mg(2+) distribution between thylakoid and stroma could serve to regulate enzyme activities in the carbon fixation pathway, and hence photosynthesis.


Chemical modifications that inhibit gelation of sickle hemoglobin. Substitution of the N-terminal amino groups with pyridoxal compounds inhibits gelation and increases the solubility of deoxy sickle hemoglobin (Hb S). Pyridoxylation of the alpha chains has considerably more effect than that of the beta chains. The increase in minimum gelling concentration of Hb S that results from modification of the alpha N-termini is the same as that produced by dilution of Hb S with an equal amount of Hb A.


Novel properties of satellite DNA from muskmelon. The purified dense satellite of muskmelon (Cucumis melo L.) represents 30% of the total DNA and forms a sharp, unimodal peak in both neutral and alkaline CsCl gradients. Spectrophotometric melting and DNA reassociation analyses revealed that one-third of the satellite is high melting and has a complexity of about 2.5 x 10(5) daltons, while the remaining two-thirds of the satellite melts 8 degrees lower and has a complexity of about 5 x 10(8) daltons. The thermal stability of reassociated satellite DNA indicates that the multiple copies of the two melting fractions are essentially identical. The sharp, unimodal peak in Cs(2)SO(4) becomes two distinct peaks when either silver or mercuric ions are included in the Cs(2)SO(4) gradient


Mechanism of renaturation of pyruvate kinase of Saccharomyces carlsbergensis: activation by L-valine and magnesium and manganese ions. Pyruvate kinase (EC 2.7.1.40) of S. carlsbergensis is a tetrameric enzyme, composed of four identical subunits each of which contains 1 mole of L-valine noncovalently bound. The enzyme readily dissociates into monomeric units. L-Valine and magnesium or manganese ions are specific primers of the renaturation process of the enzyme. The amino acid induces renaturation with a K(0.5) of 17 muM and a pseudo first-order rate constant of 0.019 min(-1) at 25 degrees with respect to the monomeric species, indicating that L-valine influences the folding of the monomeric form from a disordered state to its native conformation being followed by a spontaneous reassociation with formation of the tetrameric enzyme. Independently, magnesium and manganese ions induce the renaturation with a first-order rate constant of the same magnitude.


Models for positional information and positional differentiation. It is commonly thought that the formation of patterns in developing organisms is due to the existence of a gradient of a morphogen that determines the fate of cells as a function of position in the organism. A model is presented based on a molecular mechanism where the gradient is established by the active transport of a morphogen between source and sink. The cellular differentiation and the subsequent spatial pattern formation results from the interaction of this morphogen with the genetic regulatory mechanisms of cells. Some properties of the model are given and discussed in relation to grafting experiments in hydra.


On the molecular basis of high negative interference. Two models designed to account for high negative interference phenomena have been examined. One proposal suggests that many recombination events are the result of insertion of a small single-stranded segment of DNA into a recipient molecule. An alternative explanation for the clustering of genetic exchanges is reduction to homozygosity of genetically heterozygous sites appearing within heteroduplex overlap regions. These proposals have been examined in phage lambda by analyzing the structure of unduplicated recombinants arising from three-factor crosses with tightly linked markers. Double recombinants are found to have received substantial contributions of DNA from both parents. In addition, their patterns of genetic heterozygosity are not readily reconcilable with a single-strand insertion hypothesis. Reconstruction experiments with artifically constructed heteroduplex heterozygotes support the reduction to homozygosity hypothesis and specify the strand polarity of the heterozygous overlap region.


A functional mitotic spindle prepared from mammalian cells in culture. MITOTIC CELLS LYSED INTO SOLUTIONS OF POLYMERIZABLE MICROTUBULE PROTEIN CONTAIN A SPINDLE WHICH IS SIMILAR TO THE LIVING SPINDLE IN TWO RESPECTS: it will lose and gain birefringence when cooled and warmed, and it will move anaphase chromosomes to the opposite ends of the cell. Early anaphase cells lysed into buffers containing high molecular weight polyethylene glycol and nucleotide triphosphates will continue chromosome motion and spindle elongation in the absence of exogenous spindle subunits. These results suggest that while spindle growth requires microtubule polymerization, anaphase motions do not.


Synthesis of nerve growth factor by L and 3T3 cells in culture. Mouse submaxillary gland nerve growth factor (NGF) has been covalently joined to bacteriophage and the resulting phage conjugates remain biologically active in stimulating neurite extension from sensory ganglia. A sensitive bacteriophage immunoassay has been developed to measure concentrations of NGF as low as 1 ng/ml. With this method, we find that mouse L and 3T3 cells in culture produce a biologically active nerve growth factor that is immunologically similar if not identical to mouse submaxillary gland NGF. Since L cells are known to be a source of "conditioned medium" for tissue culture, it could be that one or more of the conditioning factor activities secreted by these cells are due to NGF itself.


Interfacial photoreactions and chemical capacitance in lipid bilayers. The electrical response of a pigmented lipid bilayer to a short laser pulse is measured by a tunable voltage clamp method. In this method, a variable access impedance permits "tuning" of the observed relaxations for optimal measurements. Analysis of the data so obtained leads to an equivalent circuit that contains a novel chemical capacitance charged by the specific photoreaction across a single membrane-water interface. This chemical capacitance is distinct from the ordinary membrane capacitance. The intrinsic chemical rate constant obtained from the equivalent circuit analysis is shown to be the pseudo-first-order rate constant of the reverse dark reaction of the reduced acceptor and the oxidized pigment. The tunable voltage clamp method of measurement and analysis allows unambiguous separation of this rate constant into resistive and capacitative elements, which are interpreted in molecular terms.


Unusual cases of myelomatosis.

Unusual cases of myelomatosis.


Human beta-D-N-acetylhexosaminidases A and B: expression and linkage relationships in somatic cell hybrids. Knowledge of the genetic relationships between beta-D-N-acetylhexosaminidases A and B (EC 3.2.1.30) may help in understanding the hexosaminidase deficiency associated with GM(2) gangliosidosis, a fatal lipid storage disease in man. Through the use of man-mouse somatic cell hybrids we have found that a gene involved in hexosaminidase A expression was linked to the genes coding for mannosephosphate isomerase and pyruvate kinase-3. The gene coding for hexosaminidase B was not linked to any of the genes coding for 25 enzyme markers tested. A combination of immunological and electrophoretic techniques was employed to identify human hexosaminidases A and B with certainty in cell hybrids. Discordant segregation of hexosaminidase A and hexosaminidase B in 60 clones indicated that the genes coding for their expression were not linked. However, hexosaminidase A was never expressed in cell hybrids in the absence of hexosaminidase B. This suggests that the gene responsible for the hexosaminidase A phenotype, linked to mannosephosphate isomerase and pyruvate kinase-3, requires the presence of the gene coding for hexosaminidase B for the expression of hexosaminidase A. These observations offer a genetic explanation for the biochemical and immunological relationships between hexosaminidases A and B and provide the framework for identifying the basic genetic defects responsible for GM(2) gangliosidosis.


Cervical percutaneous cordotomy.

Cervical percutaneous cordotomy.


Experimental alteration of the phenotype of animal cells in vivo.


Human genetic markers as tracers of tumour histogenesis.


Management of priapism in patients with chronic granulocytic leukemia.


Eosinophilic leukemia and myelofibrosis with acute blastic termination. Report of a case with review of literature.


Human leukemic cells: properties of an RNA synthesized in the presence of actinomycin D.


Professional socialization of nurses; a dean's view.


A new variant translocation (19q plus, 22q minus) in chronic myelocytic leukemia.


Professional socialization of nurses; a faculty member's view.


A message from the American Nurses' Association.


The myth of two hats.

The myth of two hats.


The director of nursing and the hat of administration.


Collective bargaining and the director of nursing.


Letter: Directors of nursing are patient advocates.


Letter: Rx for hospital environment.

Letter: Rx for hospital environment.


Editorial: Is it now, protect the public--but me first?


Professional socialization of nurses.

Professional socialization of nurses.


Emition support is--a descriptive survey.


A tool to measure nursing care of patients with a cardiovascular accident in acute phase of illness.


Editorial: Third party payment for services of independent nurse practitioners.


Incorporating the family into care.

Incorporating the family into care.


Outcome criteria as a measurement of nurse performance.


Doctor, what did you say?

Doctor, what did you say?


Congenital neuroblastoma presenting as hydrops fetalis.


Thoracic injuries. A survey of 765 patients treated at the University Hospital, Uppsala, during the years 1956-1969.


Clinicopathological conference: 36-year-old female with abdominal pain and vaginal bleeding.


Trigeminal neuralgia and mandibular dysfunction.


Comparisons between contralateral pairs of heat-induced inflammations in oral mucosa of the dog.


Studies on function and dysfunction of the masticatory system. II. Index for anamnestic and clinical dysfunction and occlusal state.


The treatment of human teeth in vitro for the replacement of the original cells, by mouse embryo cells.


Preservation of living cells lining the root of human teeth by freezing.


Maximal mandibular movements in young men and women.


Cytoxan therapy in the treatment of carcinoma of the lung. (Report of a five-year survival).


Medical grand rounds from the West Virginia University Medical Center. (Three case presentations). 1. Superior vena cava (SVC) obstruction syndrome.


Medical grand rounds from the West Virginia University Medical Center. 2. Subacute thyroiditis.


Medical grand rounds from the West Virginia University Medical Center. 3. Asbestosis.


Acute volvulus of the sigmoid colon.

Acute volvulus of the sigmoid colon.


Hyperuricemia and dicarboxylicaciduria in glycogen storage disease.


Changes in phospholipids of red cell membrane in some acquired dyserythropoietic anaemias.


Auto-immunization with acute leukemia cells: demonstration of increased lymphocyte responsiveness.


Multiple thoracotomy for metastatic pulmonary neoplasm.


Modified synaptinemal complexes in spermatocytes of Stethophyma grossum.


Dysplastic platelets and circulating megakaryocytes in chronic myeloproliferative diseases. I. The platelets: ultrastructure and peroxidase reaction.


Some aspects of chromosome structure in eukaryotes.


Nuclear DNA variation due to B chromosomes.


The integration of supernumerary chromosomes into the orthopteran genome.


Discontinuous DNA synthesis in mammalian cells.


The assembly of newly replicated DNA into chromatin.


The replication and structure of mitochondrial DNA in animal cells.


Arrangement and characterization of repetitive sequence elements in animal DNAs.


Functional organization of the mammalian genome.


The rolling helix: a model for the eukaryotic gene?


Cyclodromes and palindromes in chromosomes.


The satellite DNAs of Drosophila virilis.


The evolution of satellite DNA in Drosophila virilis.


Fluorescent probes of chromosomal DNA structure: three classes of acridines.


Clustered arrangement of tRNA genes of Xenopus laevis.


Localization of repeated DNA sequences in Xenopus chromosomes.


On the cell stage of X-Y recombination during rDNA magnification in Drosophila.


The structure and evolution of ribosomal and 5S DNAs in Xenopus laevis and Xenopus mulleri.


Unequal crossover and the evolution of multigene families.


Gene pool of higher organisms as a product of evolution.


Secondary structure maps of ribosomal RNA and its precursors as determined by electron microscopy.


The nucleolus and the rolling circle.

The nucleolus and the rolling circle.


The molecular organization of the chromomeres of Acheta involved in ribosomal DNA amplification.


Chromosome puffs and gene expression in polytene cells.


The transcription unit in Balbiani ring 2 of Chironomus tentans.


Repeated nucleotide sequences in a single puff of Chironomus tentans polytene chromosomes.


Structure and function in the genome of Drosophila hydei.


Local structural variations of the Y chromosome of Drosophila hydei and their correlation to genetic activity.


Structure and function of the Y chromosome of Drosophila hydei.


Chromosome products in Chironomus tentans salivary gland cells.


DNA sequences neighboring the duck hemoglobin genes.


Immunoglobulin genes: arranged in tandem or in parallel?


Messenger RNAs for individual histone proteins: fingerprint analysis and in vitro translation.


Immunoglobulin genes: a test of somatic vs. germ line hypothesis by RNA-DNA hybridization.


X-ray diffraction studies on oriented nucleohistone gels.


Phosphorylation of DNA-binding nuclear acidic proteins and gene activation in the HeLa cell cycle.


Enzymatic modifications and their possible roles in regulating the binding of basic proteins to DNA and in controlling chromosomal structure.


A prologue to the study of the nonhistone chromosomal proteins.


On the structural organization of the transcriptional unit in animal chromosomes.


Quantitative constraints in the arrangement of human DNA.


Transcription and structure of the genome of the cellular slime mold Dictyostelium discoideum.


Origin of mRNA in HeLa cells and the implications for chromosome structure.


Sequence arrangement in mRNA: presence of poly(A) and identification of a repetitive fragment at the 5' end.


Molecular models and combinatorial principles in cell differentiation and morphogenesis.


The organization of genetic material in eukaryotes: progress and prospects.


Quantitative electron microscopy of chromosome organization at meiotic prophase.


The delayed rejection of tumors formed from the administration of tumor cells mixed with killed Corynebacterium parvum.


Bone tumours in CF-1 mice.

Bone tumours in CF-1 mice.


The view box.

The view box.


Opiate "overdose" deaths in the District of Columbia. I. Heroin-related fatalities.


ECG problems.

ECG problems.


Colonoscopy-fiberoptic endoscopic approach to the colon and polypectomy.


Intraventricular hematoma successfully treated by surgery.


Multiple excavating pulmonary metastases.


Editorial: Medical records.

Editorial: Medical records.


Medical management of rheumatoid arthritis.


Anticoagulation. II. Anticoagulant usage in cerebrovascular disease.


Release of specific protease during mitotic cycle of L5178Y murine leukaemic cells by sublethal autolysis.


The base record: essential tool for comprehensive care.


Thyrotoxicosis developing during lithium treatment: case report.


Gangrenous sigmoid volvulus: a case report.


Editorial: Medical data questionnaire.

Editorial: Medical data questionnaire.


Medical Council of New Zealand Report on 1972 questionnaire.


Workshop on demonstrating and teaching family medicine.


Letter: Spinal units in New Zealand.

Letter: Spinal units in New Zealand.


Letter: Allergy in children.

Letter: Allergy in children.


Letter: Carcinoma of the larynx: a personal experience.


Neuroleptanalgesia in labour.

Neuroleptanalgesia in labour.


General anaesthesia for dental surgery.

General anaesthesia for dental surgery.


Serum hepatitis associated with tattooing.


The prevalence of wheezy children in Lower Hutt.


Haemophilus endocarditis and the isolation of haemophilic bacteria in blood culture: case report.


The Academy of Medical Sciences and some aspects of Swiss medicine.


Editorial: Paediatric society of New Zealand, annual meeting, Dunedin, 3-6 October 1973.


Editorial: Compensation for accidents.

Editorial: Compensation for accidents.


Presidential address.

Presidential address.


Correction of mandibular deformities.

Correction of mandibular deformities.


Central giant-cell lesion of the maxilla: enucleation and immediate reconstruction.


Gonococcal arthritis of the temporomandibular joint. Report of a case.


Myxoma of the lower jaw.

Myxoma of the lower jaw.


Autosomal dominant smooth hypoplastic amelogenesis imperfecta. Report of a case.


Benign cementoblastoma.

Benign cementoblastoma.


The multiple basal-cell nevus syndrome in a Negro family.


Odontodysplasia.

Odontodysplasia.


Physical properties of gutta-percha when subjected to heat and vertical condensation.


Configurations and deviations of root canals of maxillary first premolars.


An improved endodontic irrigation technique.


The use of fiber optics transillumination for the detection of proximal caries.


Chronic diffuse sclerosing osteomyelitis.


Bilateral transposition of maxillary canines.


Resorption of impacted maxillary third molar.


Composition and mitotic activity of the erythropoietic part of the bone marrow in chronic myeloid leukaemia.


Dental pulp photoplethysmography in human beings.


Myelomatosis and acute monocytic leukaemia.


Group G chromosomes and the susceptibility of cells of human origin to Coxsackie B viruses.


A clinical study of the autotransplantation of unerupted maxillary canines.


Potentials for the use of heparin in combination with radiation therapy, Experience with ascitic Walker 256 carcinosarcoma in weanling rats.


Stress comparisons in orthodontic arch wires.


Leukemia and the hypercoagulable state. Pathogenic and therapeutic implications.


Prosthodontics in the general practice residency.


Analysis of speech in prosthodontic practice.


Tissue management in fixed prosthodontics.


Crown retention. II. The effect of convergence angle variation on the computed stresses in the luting agent.


Anatomy of root canals. I. Permanent incisors, canines and premolars.


Graphs and scales.

Graphs and scales.


The forgotten patient in maxillofacial prosthetics.


Editorial: The dental laboratory technician.


Letter: The importance of a stable maxillomandibular relation.


Treatment of fear induced conditioned response. A case report.


Letter: Myo-Monitor centric.

Letter: Myo-Monitor centric.


Letter: Calcium sucrose phosphates.

Letter: Calcium sucrose phosphates.


Socioeconomic status, loss of teeth, and participation in a dental study.


Instruction in oral hygiene for a group of dental students; its effect on their peers.


Editorial: Women and the AAPHD.

Editorial: Women and the AAPHD.


Some observations on the use of a calcium sucrose phosphate--calcium orthophosphate complex as a desensitizing agent.


Evaluation of treatment provided through two universities, mobile dental project.


The UCLA-Whiteriver dental project.

The UCLA-Whiteriver dental project.


Letter: Acute leukemia therapy after age 50.


(51Cr)platelet kinetics in thrombocytopenia. Correlation between splenic sequestration of platelets and response to splenectomy.


The somatotopic representation of the micturition pathways in the cervical cord of man.


The cerebrospinal fluid in acute leukaemia of childhood: studies with the Cytocentrifuge. The Cytocentrifuge enables a satisfactory cytological preparation to be made when the cells in the cerebrospinal fluid are normal in number or only slightly increased. A technique has been developed and the results of its use are described in 114 consecutive samples from 50 children with acute leukaemia, with and without involvement of the central nervous system. Analysis of the results showed that 30% of the samples with a normal cell count contained leukaemic cells when examined by Cytocentrifuge. Only 74% of the samples with raised counts were found to contain leukaemic cells. Diagnosis of leukaemic meningitis based on changes in the cell count alone in cerebrospinal fluid is clearly unreliable, and the Cytocentrifuge enables a more precise assessment of the cerebrospinal fluid to be made. It also appears that changes in the levels of protein and glucose in the cerebrospinal fluid of leukaemic patients are not directly related to the presence of leukaemic cells but are the results of changes in the cell count from whatever cause. There appears to be no value in measuring protein and glucose levels when monitoring the cerebrospinal fluid in acute leukaemia for evidence of early involvement of the central nervous system.


Leukemic serum inhibition of phytohemagglutinin-induced transformation.


Proceedings: Measles and its complications. A radiological survey.


Respiratory and autonomic dysfunction following percutaneous cervical cordotomy.


Asutural maxillary vestibuloplasty.

Asutural maxillary vestibuloplasty.


The effect on speech of surgery for correction of mandibular prognathism.


Malignant chordoma.

Malignant chordoma.


Methemoglobinemia induced by high doses of prilocaine.


Psoriasiform lesions of the oral mucosa (with emphasis on "ectopic geographic tongue").


Phosphorus deficiency in cattle on two farms in Canterbury.


Nitrite and nitrate poisoning with special reference to 'grasslands tama' ryegrass.


The influence of cattle lice (Damalinia bovis and Linognathus vituli) on weight gain in beef animals.


Traumatic bone cysts of jaws.

Traumatic bone cysts of jaws.


Clear-cell acanthoma of vermilion mucosa of lower lip.


Solitary intraoral keratoacanthoma.

Solitary intraoral keratoacanthoma.


Papillary cystadenoma of ectopic minor salivary gland origin.


Maintenance of alveolar bone by the intentional replantation of roots.


The thermomechanical properties of gutta-percha. I. The compressibility of gutta-percha.


An automated complement fixation test for Brucella ovis in sheep.


Comparative radiation doses in dental radiography.


Multiple myeloma.

Multiple myeloma.


Supernumerary tooth odontoma and dens in dente.


An unusual case of multiple impacted teeth.


Multiple supernumerary and impacted teeth.


The effect of zinc deficiency on wound healing.


Suprabulbar Paresis. Congenital suprabulbar paresis and its differential diagnosis, with special reference to acquired suprabulbar paresis.


HL-A antigens and susceptibility to malignant hematological diseases.


Local leukocytes application in treating Pseudomonas ulcer in a chronic myelogenous leukemia patient.


Interdisciplinary integration in health sciences curricula.


Calcium retention of young adult males as affected by level of protein and of calcium intake.


Imidazole catalysis of sucrose hydrolysis.


The identification of risk factors in employed populations.


Prevalence of dental and occlusal anomalies in Swedish conscripts.


Awareness of malocclusion and desire of orthodontic treatment in 18-year old Swedish men.


Tissue-specific suppression of differentiation by 5-bromodeoxyuridine in vitro.


Activity of the digastric muscle in swallowing and chewing.


Isoelectric focusing in polyacrylamide gel of the membrane proteins of Streptococcus mutans and related streptococci.


Cutaneous delayed hypersensitivity responses to tumor-associated and other antigens in acute leukemia.


Improving pulmonary ventilation in anesthetized horses with the Bird Mark 9 respirator.


Vision-non-vision ataxia test battery.

Vision-non-vision ataxia test battery.


Editorial: The public policy dentist.

Editorial: The public policy dentist.


Dental prepayment and insurance: the future becomes the present.


Letter: Most corrupt reason.

Letter: Most corrupt reason.


Letter: Physician vs dentist.

Letter: Physician vs dentist.


Letter: Disagrees with technique.

Letter: Disagrees with technique.


Letter: Takes issue with reviewer.

Letter: Takes issue with reviewer.


Regional Conferences. Looking back as the second round begins.


Zahnärztetag: German dentists and researchers meet in Hamburg.


General statement of advertising and exhibiting policy.


'Healthline' service keeps Iowans informed.


Mobile dental clinic travels to Yugoslavia.


Dr. Dial en Mexico.

Dr. Dial en Mexico.


Mouthguard materials: their physical and mechanical properties.


A review: the importance of nutrition in oral health.


Continuous cost analysis for the small office.


Accredited dental schools. Council on Dental Education.


A multi-purpose anaesthetic apparatus. The Romanest.


The scanning electron microscope and the endosteal blade-vent implant.


A biophysical approach to craniofacial morphogenesis.


Three dimensional implants--development and evaluation.


Some problems with endosteal implants and their solutions.


Editorial: X-ray phobia, a consumerism "overkill".


A view from above.

A view from above.


Statistical analyses of 173 implant patients.


A new coordinated system for the controlled placement of self-tapping, titanium endodontic stabilizers.


Society activities. Report of President Kobren.


Introduction to panoramic radiographic technique.


A preliminary study of the histological effects of three different types of electrosurgical currents.


Dentistry and peer review.

Dentistry and peer review.


The carrier's point of view.

The carrier's point of view.


The effect of single daily doses of fluoride on saliva, plaque, and urine in monkeys (Macaca fascicularis).


Factors governing the use of topical fluorides: time and patient acceptability.


Teaching a dental technical skill with closed circuit television.


Homotransplantation. A case report.

Homotransplantation. A case report.


Overcoming TMJ problems in oral reconstruction.


Modified removable appliances from prefabricated components.


Letter: Questions organized dentistry' role.


Detecting hypertension in dental patients.


Editorial: General anesthesia for dental outpatients.


Mechanical condensation technic for consistent placement of amalgam.


Staff and patients are 'right at home' in residence office.


Dental insurance: crossing the threshold.


Call your corporation to order.

Call your corporation to order.


Periodontal aspects of restorative dentistry.


Changes in facial skin temperature associated with unilateral chewing.


Relation between facial morphology and activity of the masticatory muscles.


Age changes in the two-point discrimination threshold in skin innervated by the trigeminal nerve.


A new method to determine the dimensional behaviour of dental amalgam.


Influence of muscle activity on remodelling of bones in the rat.


An apparatus for the synchronous registration of EMG activity in jaw muscles and of vibrations in the masticatory system.


Masticatory function and oral rehabilitation.


Stresses and deflections in the floor of model cavity preparations.


A method for jaw movement registration.

A method for jaw movement registration.


Efficacy of and possible differences in tolerance to L-dopa tablets with different rates of release of the active substance.


Effects of long-term primidone therapy in a dog.


Gilles de la Tourette's disease: multiple vocal and motor tics.


The effect of chewing on the ph of dental plaques after carbohydrate consumption.


Ten cases of so-called long survival in children with acute lymphoblastic leukemia.


The distribution of proteolytic and alkaline phosphatase activities in human saliva treated with sodium deoxycholate.


Acute leukaemia associated with an abnormal genotype.


Structure activity relations of some indolealkylamines in comparison to phenethylamines on motor activity and acquisition of avoidance behavior.


Investigation of the dentition of oral-cleft population.


The evolution of a synorgan. Nineteen stages concerning teeth and dentition from the pelycosaur to the mammalian condition.


Bilateral pseudotumors of the pelvis in a patient with Christmas disease. With notes on localization by radioactive scanning and ultrasonography.


Community health nursing and change-are we prepared?


Nehi Tane (male nurse).

Nehi Tane (male nurse).


The atom--and public health.

The atom--and public health.


A nursing care study.

A nursing care study.


Music therapy.

Music therapy.


Reversal of retinal feedback of binocular eye motions in depth vision.


The separate functions of cleaning and sterilizing soft contact lenses.


Systemic blood pressure as a diagnostic tool in glaucoma.


Editorial: Prevention will prevail.

Editorial: Prevention will prevail.


THETA: Teenage Health Education Teaching Assistants.


Predicting optometry grades from the OCAT and preoptometry grades.


Theoretical and practical aspects of crowding in the human dentition.


Evaluation of sensation after segmental alveolar osteotomy in 22 patients.


A misingested hand reamer: report of case.


Purification of vaccinia haemagglutinin.


DNA base composition of coagulase-negative staphylococci associated with urinary tract infection.


Antibodies against three different structural components of measles virus in patients with multiple sclerosis, their siblings and matched controls.


Road traffic casualties in a surgical department. A prospective study of a one-year hospital material, with special reference to epidemiology, official statistics, hospital load and economy.


A spectrophotometric method for analysis of oxygen consumption in vitro on the microscale.


The effect of quantitated training on the capacity for short and prolonged work.


Treatment of carcinoma of the lids and orbit.


Burn encephalopathy or hexachlorophene poisoning?


Some medical aspects of sports.

Some medical aspects of sports.


Diagnostic patterns in Disability: New Jersey and the nation.


Communicable diseases in New Jersey.

Communicable diseases in New Jersey.


Letter: Use of halothane in United States.


Letter: Hazards in use of dipyrone.

Letter: Hazards in use of dipyrone.


Letter: Treatment of recurrent parotitis in children.


Letter: Participation on Hospital Committees.


Letter: Giant cell tumor and Paget's disease.


Increased efficiency of leukocyte collection from patients with chronic myelocytic leukemia.


Conservative treatment of a large mandibular cyst. A case report.


A method of anchorage for orthodontic movement of unerupted teeth.


Histologic evaluation of treatment of epidermoid carcinoma in the oral cavity with methotrexate and 5-fluorouracil.


Management of wound breakdown after primary repair of a facial laceration.


Department of Oral and Maxillofacial Surgery Jacksonville Hospitals Educational Program University of Florida Affiliate.


Central mucoepidermoid tumor (carcinoma) of the mandible.


Letter: Catecholamine levels in spinal cord injury.


Bodily retraction of maxillary incisors with round wires.


A comparison of chronologic age and physiologic age as predictors of tooth eruption.


Surgically corrected mandibular prognathism. A cephalometric analysis of fifty cases.


Granulopoietic activity of urine and cells from patients with chronic granulocytic leukemia.


Editorial: Professional discrimination retards implant progress.


Phonetics, function, and anterior occlusion.


Induction of delta-aminolevulinic acid synthetase during erythroid differentiation of cultured leukemia cells.


Compatibility of a composite resin with pulp insulating materials. A scanning electron microscope study.


Some perspectives on the pathogenesis of periodontal disease.


Possible role of immune phenomena in periodontal tissue destruction. Morning discussion.


Cysteine scavengers. 2. Synthetic alpha-methylenebutyrolactones as potential tumor inhibitors.


Data banks and computer morphometrics: The role of human and electronic brains in monitoring craniofacial growth.


Direct participation of dCMP hydroxymethylase in synthesis of bacteriophage T4 DNA. In order to retain in an in situ system the control mechanisms involved in synthesis of bacteriophage T4 DNA, infected cells were made permeable to nucleotides by plasmolysis with concentrated sucrose. Such preparations use exogenous deoxyribonucleotides to synthesize T4 phage DNA. As has been observed with in vivo studies, DNA synthesis was drastically reduced in plasmolyzed preparations from cells infected by amber mutants of genes 1, 32, 41, 42, 43, 44, or 45. Added 5-hydroxymethyl dCTP did not bypass either a mutant of gene 42 (dCMP hydroxymethylase) or of gene 1 (phage-induced deoxyribonucleotide kinase). In a phage system lacking deoxycytidine triphosphatase (gene 56) and the gene-46 product, and therefore incorporating dCTP into DNA, dCTP incorporation did not require dCMP hydroxymethylase, in keeping with in vivo results. With a triple amber mutant of genes 1, 46, and 56 only slight incorporation of dCTP occurred. By contrast, in experiments performed in vivo the synthesis of cytosine-containing DNA was unaffected by an amber mutation in gene 1. These studies provide evidence that dCMP hydroxymethylase, in addition to its known catalytic function, has a second, more direct, role in phage T4 DNA synthesis, apparently in recognition of hydroxymethyl dCTP. The role of the phage-induced deoxyribonucleotide kinase in T4 DNA synthesis in the plasmolyzed system remains unresolved.


A ribosome dissociation factor from rabbit reticulocytes distinct from initiation factor M3. A ribosome dissociation factor (DF), from a 0.5 M KCl wash fraction of rabbit-reticulocyte-ribosomes, has been purified by Sephadex G-200, phosphocellulose, DEAE-cellulose, and hydroxyapatite chromatography. The most purified preparation displayed one major and several minor bands on 3.75% acrylamide gels.DF cannot replace IF-M(1), IF-M(2A), IF-M(2B), IF-M(2), EF-1, or EF-2 in poly(U)-directed polyphenylalanine synthesis at low Mg(++) concentrations or in endogenous mRNA-directed globin synthesis. Conversely, these initiation and elongation factors showed little or no dissociation activity, even when assayed at levels 5-10 times greater than those required to saturate a polypeptide synthesis assay. Reticulocyte DF thus appears to be a distinct factor.


Dopamine-beta-hydroxylase: a tetrameric glycoprotein. Dopamine-beta-hydroxylase (EC 1.14.2.1) has been isolated as a pure protein from bovine-adrenal glands. Although the molecular weight of the native protein is well established (290,000), sodium dodecyl sulfate-gel electrophoresis under dissociating conditions gave a single band with a molecular weight of about 75,000. The enzyme contains about 4% carbohydrate, which consists of residues of mannose, glucosamine, galactose, glucose, fucose, and sialic acid. The pure enzyme also contains about 4 atoms of copper per molecule. It is concluded that dopamine-beta-hydroxylase is a tetrameric glycoprotein.


The diet dilemma in dentistry.

The diet dilemma in dentistry.


The motivational aspects of teaching patients dental home care.


Biologically and chemically pure mRNA coding for a mouse immunoglobulin L-chain prepared with the aid of antibodies and immobilized oligothymidine. The mRNA coding for a mouse immunoglobulin L-chain was prepared from MOPC-321 myeloma polysomes specifically precipitated with antibodies directed against L-chains, followed by chemical purification on oligo(dT)-cellulose. Biological purity (capacity to program the synthesis only of L-chain) was calculated to be >/=95%. This value was based on the estimation of contamination by non-L-chain mRNA activities that were present in large abundance in RNA preparations extracted from the total polysome population. A similar degree of purity was calculated from the extent of precipitation of myeloma and nonmyeloma polysomes with anti-L-chain and non-L-chain antibodies. Chemical purity (95%) was determined from the amount of rRNA in the mRNA preparation by scanning of appropriate gels. In a cell-free system, the purified mRNA directed the synthesis of two precursors heavier than L-chain by about 1300 and 4700 daltons. Cell-free products labeled with 10 [(14)C]aminoacids yielded 27 out of 28 expected L-chain tryptic peptides and four additional peptides. Most probably the latter were derived from extra pieces in the precursors, and the apparent loss of one peptide was due to modifications at the N-terminus. The main fraction of L-chain mRNA was composed of two species of about 420,000 and 450,000 daltons. These molecules are much larger than that required to code for a mature L-chain (calculated about 250,000). The additional nucleotide mass can be accounted for in part for the coding of the extra piece (about 50,000) and in part for the polyadenylate moiety.


Preliminary evidence for a microsomal precursor to human parathyroid hormone. Human parathyroid glands from a patient with chronic renal failure were used to study in vitro biosynthesis of immunoreactive parathyroid hormone. Parathyroid glands were incubated in the presence of [(3)H]leucine, and classical subcellular fractions were prepared. peptides from acetic acid extractions of the fractions were separated on Sephadex G-75 Superfine. Eluates were assayed for immunoreactive parathyroid hormone by a double-antibody technique. Leucine was incorporated into several large immunoreactive peptides of parathyroid hormone having estimated molecular weights of >25,000, 18,000, and 13,000. The large forms of immunoreactive parathyroid hormone were prominant in the microsomes. The secretion granule fraction, as well as the patient's serum, contained principally immunoreactive parathyroid hormone with an apparent molecular weight of 10,000.


Self-association of cholesterol in aqueous solution. Cholesterol has a maximum solubility in aqueous solutions of 1.8 mug/ml or 4.7 muM. It undergoes a thermodynamically reversible self-association with a critical micelle concentration of 25 to 40 nM at 25 degrees . The cholesterol micelle is heterogeneous in size, probably rodlike in shape, and stabilized by an unusually high interaction energy between the aggregated monomers.


Isolation of a glucagon-containing peptide: primary structure of a possible fragment of proglucagon. The heterogeneity of crystalline bovine (ox)/porcine glucagon has been examined by gel filtration and ion-exchange chromatography. A strongly basic peptide that reacted well with antibodies to bovine/porcine glucagon was isolated and its primary structure was determined. The amino-acid sequence of the NH(2)-terminal 29 residues of the 4500-dalton peptide is identical with that of intact bovine or porcine glucagon. The remaining eight residues at its COOH-terminus are Lys-Arg-Asn-Asn-Lys-Asn-Ile-Ala. Small amounts of other glucagon-immunoreactive peptides having molecular weights ranging from 3700 to 9000 were also detected in crystals of bovine/porcine glucagon. We propose that the 37-residue peptide is a fragment of bovine or porcine proglucagon.


Factor VIII recombination after dissociation by CaCl12. Factor VIII is a large protein molecule of molecular weight 2,000,000 or larger that elutes in the void volume on agarose gel chromatography. It has been shown previously that high concentrations of alkali halides and, more specifically, 0.25 M Ca(2+) dissociate the molecule into a large carrier protein and a small fragment that retains the factor VIII activity. Factor VIII was prepared from normal canine plasma collected in sodium oxalate and heparin and adsorbed with BaSO(4). Results with Ca(2+) dissociation were the same as those obtained with fraction prepared from canine plasma collected in sodium citrate. The addition of 0.1 M epsilon-aminocaproic acid in the dissociation step had no effect. Fractionation of canine hemophilic plasma produced preparations without activity, and no activity was found when these inert preparations were dissociated with Ca(2+). These results indicate that the Ca(2+) dissociation is a true dissociation and not caused by enzymatic degradation by plasmin, thrombin, or activated factors VII, IX, or X. The apparent molecular weight of the small active fragment of factor VIII determined by gel chromatography was about 100,000. Finally, when the large carrier protein and the small active fragment of factor VIII were separated by gel chromatography, mixed, and dialyzed free of Ca(2+), they recombined to form a large active molecule that appeared in the void volume on agarose gel chromatography.


Efficient translation of tobacco mosaic virus RNA and rabbit globin 9S RNA in a cell-free system from commercial wheat germ. Extracts prepared from commercially available wheat germ efficiently translate messenger RNAs from either viral or eukaryotic origin. The addition of tobacco mosaic virus RNA stimulated amino-acid incorporation more than 100-times and rabbit globin 9S RNA between 20- and 30-times. The in vitro product directed by globin 9S RNA comigrated precisely with authentic rabbit globin on sodium dodecyl sulfate-polyacrylamide gels. Furthermore, during high voltage ionophoresis two [(35)S]methionine-labeled tryptic peptides synthesized in vitro comigrated in two dimensions with alphaT5 and betaT5 tryptic peptides from authentic [(35)S]methionine-labeled rabbit globin.


Polyadenylation of maternal RNA of sea urchin eggs after fertilization. Between fertilization, or parthenogenetic activation, and the two-cell stage, the content of polyadenylic acid in sea urchin eggs doubles, and the increase occurs primarily in the ribosome-polyribosome fraction. The increase is due to polyadenylation of preexisting RNA molecules synthesized during oogenesis. The polyadenylation occurs in activated, enucleated merogons. It is argued that cytoplasmic polyadenylation may play a role in mobilization of maternal messenger RNA for translation and the polyadenylic acid does not subserve an exclusively nuclear function.


Influence of guanine nucleotides and elongation factors on interaction of release factors with the ribosome. Release of formylmethionine from the reticulocyte ribosomal substrate, f[(3)H]Met-tRNA.ribosome, is promoted by reticulocyte release factor (RF). The initial rate of this reaction is stimulated by GTP but inhibited by GDPCP. Formation of an RF.UA[(3)H]A(2).ribosome complex is a measure of the binding of reticulocyte RF to the ribosome, and the recovery of this complex is increased by GDPCP and, to a lesser extent, GTP. These studies suggest that GTP is involved in the initial association of RF with the ribosome and that hydrolysis of the gamma-phosphate of the guanine nucleotide is required at a subsequent rate-limiting step. The ribosomal-dependent fMet-tRNA hydrolysis and GTPase activities of reticulocyte RF are inhibited when elongation factor (EF)-2 is bound to the respective ribosomal substrate in the presence of fusidic acid and GDP. When EF-G is bound to the f[(3)H]Met-tRNA.AUG.ribosome substrate with fusidic acid and GDP, the fMet-tRNA hydrolysis activity of Escherichia coli RF-1 and RF-2 is also inhibited. The binding of reticulocyte RF and E. coli RF-1 or RF-2 to their respective ribosomes is prevented when fusidic acid.EF-2/EF-G.GDP.ribosome complexes are used.


Messenger selection by bacterial ribosomes. The counterpart of Escherichia coli initiation factor 3(IF-3) was isolated from Caulobacter crescentus, purified to homogeneity, and used in comparative studies on in vitro translation of RNA from the C. crescentus RNA phage Cb5 and of coliphage MS2 RNA. The two phage RNAs are similar in physical properties and analogous in genetic content. The factor, C-IF-3, substitutes for E. coli IF-3 and promotes correct translation of MS2 RNA by E. coli ribosomes. Conversely, E. coli IF-3 substitutes for C-IF-3 in translation of Cb5 RNA by C. crescentus ribosomes. However, each phage RNA could be translated only by host ribosomes or by mixed ribosomes containing the host 30S subunit. C-IF-3 dissociates C. crescentus and E. coli 70S ribosomes into subunits. It binds phage, ribosomal, and, less efficiently, transfer RNA.


Transposition of rotameter bobbins.

Transposition of rotameter bobbins.


RNA polymerases of maize. Purification and molecular structure of DNA-dependent RNA polymerase II. Nuclear DNA-dependent RNA polymerase II has been purified from leaves of Zea mays by a new procedure that improves enzyme stability and thus permits more manipulation during purification. The purification procedure includes a heating step, gel filtration on Sepharose 6B and 4B, and chromatography on DEAE- and DNA-celluloses. This method of purification yields an enzyme that exhibits maximal activity when denatured DNA is used as a template. Electrophoresis of highly purified enzyme on polyacrylamide gels containing sodium dodecyl sulfate indicates that maize RNA polymerase IIa is composed of several polypeptide subunits. The most highly purified preparations contain polypeptides with molecular weights of 200,000, 160,000, 35,000, 25,000, 20,000, and 17,000.


Fibrinogen-fibrin degradation products during labour and during the puerperium.


Lymphography in tuberculosis.

Lymphography in tuberculosis.


The resistance of Entonox valves.

The resistance of Entonox valves.


Upper limits of resistance of apparatus for inhalation analgesia during labour. Response of mothers to increasing apparatus resistance.


Epilepsy and mortality rate and cause of death.


Epileptics not in treatment.

Epileptics not in treatment.


An animal model for the ketogenic diet.

An animal model for the ketogenic diet.


Numerical coding for types of seizure based on the clinical and electroencephalographical classification of epileptic seizures.


Local anesthesia and experimental epilepsy.


Editorial: Curricular trends.

Editorial: Curricular trends.


Development and reporting of course information for accreditation: a systematic strategy.


Delta9-tetrahydrocannabinol and epilepsy in the photosensitive baboon, Papio papio.


The use of PERT in preparing for accreditation review.


Comparison of clinical performance of dental therapist trainees and dental students.


Differences between American and British dental students in perception of dentistry and the job of practicing dentistry.


The nurse and the ventilator.

The nurse and the ventilator.


Sleeptalking and creativity: a case study.


Glycogen storage disease, types I to X: criteria for morphologic diagnosis.


The therapeutic value of suffering.

The therapeutic value of suffering.


Mode-of-being and kidney disease.

Mode-of-being and kidney disease.


The movement of objects at a distance.

The movement of objects at a distance.


The hypertensive balloon. A beneficial synergism for the salvage of ischemic myocardium.


Hand, foot and mouth disease.

Hand, foot and mouth disease.


Anatomy of root canals. II. Permanent maxillary molars.


Editorial: Temples of Asclepius.

Editorial: Temples of Asclepius.


The tissue response to endosteal blade implants--microradiographic and tetracycline marking. I.


Letter: Patient air intake valve of the Cape Ventilator.


Measurement of DNA synthesis by 3H-thymidine incorporation into needle aspirates from human tumors.


Oral exfoliative cytology in reverse smokers having carcinoma of hard palate.


A comparative filter technique study and the relative efficiency of these sieves as applied in sputum cytology for pulmonary cancer cytodiagnosis.


Letter: Feminization in tumors of Sertoli-Leydig cells.


The use of a polyvalent antigen in complement fixation tests for bovine leptospirosis.


Complement fixing and agglutinating antibody responses and Leptospiruria in calves inoculated with leptospira serotypes pomona, hardjo, copenhageni or ballum.


Editorial: Future scope of dental practice.


Delayed toxic effect of busulfan on the marrow.


Effects of varying sequence and amount of training on learning and performance in preclinical endodontics. II. Study on amount of training.


Experimental ergotism in sheep.

Experimental ergotism in sheep.


Myocardial abscess and infarction.

Myocardial abscess and infarction.


Report of the commission on classification and statistics for oral conditions. 1972-1973.


Report of the commission on dental education 1972-1973.


Report of the commission on dental materials, instruments, equipment and therapeutics. 1972-1973.


Report of the commission on public dental health services 1972-1973.


Factors influencing the changing clinical expression of the depressive process in children.


Vascular access by means of surgically created arteriovenous fistulas in the chemotherapy of acute leukemia: a preliminary report.


Quantitative analysis of mass and energy balance in non-ideal models of the renal counterflow system. A modified Newton-Raphson method for solving finite difference equations for the renal counterflow system is described. The method has proved generally stable and efficient, and has given significant computational results for a variety of models: calculations on single solute models of the coupled vasa recta nephron counterflow system have shown that for large water and solute permeabilities of the exchanging membranes, behavior of the non-ideal system approaches that of the previously described ideal central core model. Concentration by salt and urea mixing in two solute models has been analyzed and previous conclusions from central core models have been found to remain valid in non-ideal systems. The numerical solutions have set some order of magnitude bounds on permeability requirements for concentration in different types of non-ideal systems. Finally, from the detailed concentration profiles it has been possible to relate the rate of free energy creation and dissipation from transmembrane transport of solutes and water to the net rate of free energy efflux from the counterflow system, and so to compute in a given model the fraction of power used for solute concentration.


Transcription of polydeoxythymidylate sequences in the genome of the cellular slime mold, Dictyostelium discoideum. Messenger RNA of the cellular slime mold, Dictyostelium discoideum, contains about equimolar amounts of two classes of poly(adenylic acid) [poly(A)]; one is about 25 nucleotides long and the second about 100 nucleotides long. At least half of the messenger RNA molecules contain one sequence each of poly(A)(25) and poly(A)(100); both poly(A) sequences are located near the 3' end of messenger RNA, and the kinetics of their appearance on messenger RNA precursor indicates that poly(A)(25) is added before poly(A)(100). Dictyostelium nuclear DNA contains 14,000-15,000 sequences of poly(dT)(25) which could code for the smaller poly(A) residues. The poly(A)(100) must be added post-transcriptionally. The poly(dT)(25) sequences are interspersed throughout the genome and may well represent transcription termination regions.


Structure of the Krasnovskii photoreduction product of chlorophyll a. A proton magnetic resonance study at 220 MHz shows the Krasnovskii intermediate in the photoreduction of chlorophyll a by hydrogen sulfide to be beta,delta-dihydrochlorophyll a.


Population structure in relation to cost of selection. The opposing requirements in an evolving population for a rapid rate of multiple gene substitution and for the maintenance of normal population size can be reconciled in a variety of ways. The ways out of the impasse suggested here invoke deviations from the usual assumption of a large continuous population with constant numbers. In a colonial population system there may be significant random fluctuations in the accidental mortality rate between different colonies; and those colonies with reduced numbers of accidental deaths could tolerate the larger number of selective deaths that go hand in hand with rapid evolution. In new daughter colonies founded by one or a few colonizing individuals from a large polymorphic ancestral population, some genes may reach complete fixation in one or a few generations, without the usual concomitant selective cost. Or, in the same setup, the favored alleles may change by chance from rare to moderately common, but not to complete fixation, during the founding of some daughter colonies; and this raises the allele frequencies above the low range, where the cost of selection is greatest, so that the cost of further selective changes is bearable.


A soluble super-active form of insulin.

A soluble super-active form of insulin. Insulin-like material can be extracted from insulin-Sepharose. This soluble material elicits super-insulin responses from mammary epithelial cells. It stimulates the accumulation of alpha-aminoisobutyric acid by virgin mouse mammary cells, which are unresponsive to insulin itself. It exerts a greater stimulatory effect on mammary cells from pregnant mice than insulin. It also is more efficacious than insulin as a stimulant of DNA synthesis and the combined activities of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and phosphogluconate dehydrogenase (EC 1.1.1.43). Its specific biological activity on these cells is more than five times greater than that of insulin.


Circadian function in the photoperiodic induction of gonadotropin secretion in the white-crowned sparrow, Zonotrichia leucophrys gambelii. Photosensitive White-crowned Sparrows (Zonotrichia leucophrys gambelii) previously maintained on short day lengths (8-hr light; 16-hr darkness) were transferred to complete darkness. At various intervals thereafter (2-100 hr) they were exposed to a single 8-hr light period. To determine if the light period had been inductive, plasma luteinizing-hormone concentration was measured by radioimmunoassay in blood samples taken before and after the light period. Inductive light periods recurred at approximately daily intervals. The data provide further evidence for the involvement of a circadian rhythm in time measurement in the photoperiodic responses of birds.


X-ray diffraction studies of nucleohistone: a polyhelical model of chromosome organization. The possibility that nucleohistone is constituted by a helical arrangement of DNA molecules is analyzed in this paper. A polyhelical model of nucleohistone in plectanemic double coils of variable dimensions is found to be compatible with the x-ray diffraction results obtained in this and other laboratories. The radius of the coils varies between 35 and 45 A, whereas the pitch varies between 200 and 120 A. Another part of nucleohistone is much less coiled and contributes to the "background" scattering of the sample. This model is compatible with a lampbrush organization of the chromosome.


Cytoplasmic inheritance of chloramphenicol resistance in mouse tissue culture cells. A chloramphenicol-resistant mutant, isolated from mouse A9 cells, was enucleated and fused with a nucleated chloramphenicol-sensitive mouse cell line. Resultant fusion products, cytoplasmic hybrids (or "cybrids"), were selected as resistant to chloramphenicol, and had the nuclear markers and chromosome complement of the chloramphenicol-sensitive parent. These cybrids appeared at the high frequency of 2-8 per 10(4) cells plated. Neither parent produced any colonies when plated under identical selective conditions. Fusion between enucleated chloramphenicol-sensitive cell fragments and the chloramphenicol-sensitive cell produced no resistant colonies, suggesting that chloramphenicol resistance is not due to an increase in the ratio of cytoplasm to nucleus. Furthermore, fusions between resistant and sensitive nucleated cells produced resistant hybrids at a frequency 100 times less than that of resistant cybrids. Thus, these stable chloramphenicol-resistant cybrids result from the fusion of a chloramphenicol-resistant cytoplasm with a chloramphenicol-sensitive cell. It is proposed, therefore, that chloramphenicol resistance is a cytoplasmically inherited characteristic in this mouse cell line.


The quaternary structure of delta-aminolevulinic acid dehydratase from bovine liver. The quaternary structure of delta-aminolevulinic acid dehydratase (5-aminolaevulinate hydrolyase, EC 4.2.1.24) from bovine liver was examined by analytical ultracentrifugation, polyacrylamide gel electrophoresis, and electron microscopy. The molecular weights, determined by sedimentation-velocity and sedimentation-equilibrium experiments, were 289,000 and 282,000, respectively. The molecular weight of the subunit in 6 M guanidine. HCl was 34,900 as determined by sedimentation-equilibrium and 35,000 as estimated by polyacrylamide gel electrophoresis. No evidence was obtained for the presence of a smaller polypeptide. It appears therefore that delta-aminolevulinic acid dehydratase from liver is composed of eight subunits. The molecules of the enzyme deposited in thin layers of negative stain were generally square with an edge length of 85-90 A. On the assumption that the subunits are spherical in shape with a diameter of 44 A and a density of 1.36 g/cm(3), the molecular weight of the octamer is calculated to be 292,000. The particles appear to consist of four discrete lobes arrayed at the four corners of a square. The above conclusion that the dehydratase possesses eight subunits can be readily reconciled with the appearance of the enzyme in the electron microscope if it is postulated that the eight subunits are arranged at the corners of a cube. Therefore, it would follow that the subunits are arranged with dihedral (D(4)) symmetry.


Decarboxylation to tyramine: a major route of tyrosine metabolism in mammals. Metabolism of tyrosine was examined in mice, some of which had been treated with an inhibitor of aromatic-L-amino-acid decarboxylase. The results of the study indicate that as the plasma and tissue levels of tyrosine are elevated, decarboxylation to tyramine becomes the predominant route of metabolism. At the highest dose of tyrosine used (1.5 g/kg), it was found that 42% of the administered dose was decarboxylated within 6 hr and only 11.5% was metabolized by the tyrosine aminotransferase pathway.


Contact-mediated myogenesis and increased acetylcholinesterase activity in primary cultures of mouse teratocarcinoma cells. Transplantable mouse teratomas are known to contain multipotential teratocarcinoma stem cells analogous to early embryo cells and capable of giving rise to a wide variety of specialized cell types in vivo when they attach to a substratum; if they are grown instead in suspension in the body cavity, they form multicellular embryoid bodies which proliferate with little or no cell specialization. Thus, changes initiated at the cell surface may play some role in promoting early cell differentiation. In order to establish an in vitro system for experimental investigation of this hypothesis, embryoid body cells were explanted under conditions of cell attachment versus suspension and maintained in primary culture. Because cell differentiation in previous reports was relatively limited in vitro, the two cellular populations were first compared for genesis of a quantifiable macromolecular phenotype, acetylcholinesterase (AChE) activity, which characterizes several of the cell types most commonly formed in the attached tumors in vivo. The attached cells produced markedly increased levels of AChE activity within a few weeks, while cells in suspension retained basal levels. AChE was histochemically visualized and was found to occur chiefly in cells undergoing myogenesis, especially during myotube formation. Aberrant muscle fibers formed and became predominant in the cultures. When embryoid bodies were first fractionated by increasing size, which reflects their progressive differentiation, the smallest ones, with relatively more multipotential cells and no apparent muscle cells, also showed AChE increase in attached cultures. The results are consistent with the view that attachment of the cell surface to a substratum may play a critical role in initiating some cellular developmental commitments, as well as in sustaining differentiation of cells whose specialization has already been determined. Further experimental modifications of this primary culture system of teratocarcinoma cells should be useful in analyzing cell-substratum relations and cell-surface changes in early mammalian development.


Prevention of malignant change in mammalian cells during prolonged culture in vitro. Mixed cultures of epithelial cells and fibroblasts, derived from primary cultures of the skin of embryo rats, grown always in rubber-stoppered T-60 flasks, first yielded a transplantable tumor from the 52nd passage, at the end of 13 months of frequently repeated subculture. A group of subcultures, derived from the 22nd passage, grown under the same medium, with the addition of 1% oxyhemoglobin, failed to yield a tumor in 23 months of repeated subculture. A return of these cultures to the regular medium with oxyhemoglobin, yielded a tumor in 4 months, after 12 more passages. Cultures of transformed cells that had regularly yielded a transplantable tumor, for 6 years, up to the 305th passage, continued to yield transplantable tumors when 1% oxyhemoglobin was added to the medium. The cells remained highly atypical, microscopically, and there was no indication of reversal of the malignancy. Although oxyhemoglobin in the medium of cell cultures seems to have had the ability to keep malignancy in abeyance, it did not reverse the established malignant transformation of the cells.


Role of DNA-dependent RNA polymerase 3 in the transcription of the tRNA and 5S RNA genes. Mouse myeloma cells have previously been shown (L. B. Schwartz, V. E. F. Sklar, J. A. Jaehning, R. Weinmann & R. G. Roeder, submitted for publication) to contain two chromatographically distinct forms of RNA polymerase III (designated III(A) and III(B)). The enzymes are unaffected by low alpha-amanitin concentrations which completely inhibit RNA polymerase II, but they exhibit characteristic inhibition curves (identical for III(A) and III(B)) at higher toxin concentrations. RNA polymerase I was unaffected at all alpha-amanitin concentrations tested. Myeloma RNA polymerases II, III(A), and III(B) appear to be inhibited by the same mechanism, since the toxin rapidly blocks chain elongation by each enzyme. The characteristic alpha-amanitin sensitivity of RNA polymerase III has been employed in studies of the function(s) of the class III RNA polymerases. Isolated myeloma nuclei and nucleoli contińue to synthesize RNA via the endogenous RNA polymerases when incubated in vitro. With nuclei, newly synthesized 4S precursor (pre-4S) and 5S RNA species were detected by electrophoretic analysis either of the total nuclear RNA or of the RNA released into the supernatant during incubation. The synthesis of both pre-4S and 5S RNA species was inhibited by alpha-amanitin, but only at high concentrations; and the alpha-amanitin inhibition curves for these RNAs were identical to those obtained for solubilized RNA polymerases III(A) and III(B). In control experiments it was shown that the endogenous RNA polymerase II activity of isolated nuclei was inhibited by alpha-amanitin concentrations similar to those required to inhibit purified enzyme II. However, 40-50% of the endogenous activity of nuclei and 100% of the endogenous activity of purified nucleoli was completely resistant to the high alpha-amanitin concentrations necessary to inhibit the RNA polymerase III activities. These experiments rule out nonspecific inhibitory effects in the endogenous systems. These results unequivocally demonstrate the role of RNA polymerase III (III(A) and/or III(B)) in the synthesis of (pre) 4S RNAs and a 5S RNA species.


Thermodynamics of micelle formation: prediction of micelle size and size distribution. This paper presents a simple theory for the calculation of micelle size and other properties of micelleforming systems. The theory is based on the separate estimation of the components of the free energy arising from hydrophobic attraction and from head group repulsion, each as a function of micelle size. The difficult problem of an a priori calculation of the repulsive factor is circumvented by using experimental values of this parameter, derived from pressure-area curves of monolayers at an interface between an aqueous solution and liquid hydrocarbon. Though some parameters of the theory are still somewhat uncertain, self-consistent and physically realistic values can be assigned that lead to almost exact prediction of experimental micelle sizes and critical micelle concentrations for two distinctly different ionic detergents.


The amplified ribosomal DNA of dytiscid beetles. During oogenesis in many animals there is a massive extrachromosomal synthesis of the genes for ribosomal RNA. In Dytiscid beetles, as in the toad Xenopus, the amplified ribosomal DNA occurs as circular molecules of different sizes. The circles fall into size classes that are integral multiples of a unit circle. It is probable that the unit circle contains the coding sequence for one precursor ribosomal RNA molecule plus accompanying spacer sequences.


Formation of Sindbis virus capsid protein in mammalian cell-free extracts programmed with viral messenger RNA. Extracts from Krebs II ascites cells and rabbit reticulocytes effectively synthesize viral proteins with Sindbis viral mRNA isolated from Sindbis-infected BHK cells. The major product is identical to Sindbis capsid protein on the basis of its electrophoretic mobility in sodium dodecyl sulfate-acrylamide gels and two-dimensional tryptic-peptide fingerprints. Various amounts of several additional discrete polypeptides are formed, depending on the components of the cell-free extracts. One of these polypeptides may be a prematurely terminated part of the viral-capsid protein, while another is larger in molecular weight than capsid protein but contains the capsid tryptic peptides. Several of the proteins formed in vitro also are detected in extracts of Sindbis-infected BHK cells labeled with [(35)S]methionine. The three proteins found in Sindbis virions are postulated to originate by proteolytic cleavage from a larger molecular weight polypeptide precursor that is translated from a polycistronic mRNA presumed to contain a single site for initiation of protein synthesis. The two in vitro systems appear to translate this polycistronic viral mRNA to yield specific viral capsid although no evidence was found for post-translational proteolysis. Other mechanisms for production of the capsid protein in the cell-free extracts are considered, and some of these may function in the viral-infected cell where unusually large amounts of viral capsid proteins are frequently detected.


Stimulation of mitogenesis in normal and leukemic human lymphocytes by divalent and tetravalent lima bean lectins. Two hemagglutinating components purified from the lima bean and composed of identical 62,000-molecular-weight subunits have mitogenic activity in normal and leukemic human lymphocyte cultures. Component II (247,000 molecular weight), a tetramer with four saccharide binding sites, is severalfold more active than component III (124,000 molecular weight), a dimer with two binding sites per molecule, as a mitogen for normal lymphocytes. Component II also stimulates mitogenesis in populations of cultured leukemic lymphocytes and appears to have greater activity than phytohemagglutinin-P in leukemic lymphocyte cultures obtained from some patients. Lima bean component III has minimal mitogenic activity toward leukemic lymphocytes. Components II and III appear to compete for the same cell-surface binding sites, but component II has a much greater capacity than component III to trigger DNA synthesis at low concentrations (2.5-25 mug/ml) in normal lymphocyte cultures. These results suggest that the mitogenic activity of lima bean lectin components is directly related to their valence.


On the possibility that DNA repair is related to age in non-dividing cells. Possible age-related deterioration in the efficacy of DNA repair was investigated in a complement of non-dividing mammalian cells which is not replenished during the lifetime of the animal. Internal granular-layer neurons were extracted from the cerebella of beagle dogs, aged from 7 weeks to 13 years, following exposure in situ to 4700 rads of collimated (60)Co gamma rays. The alkaline sucrose-gradient sedimentation profiles obtained from the DNA of those neurons after various post-irradiation periods in situ can be interpreted: (a) that there is not an age-associated decrease in the ability of the cells to rejoin the single-strand breaks induced by radiation, but (b) that there may be an age-associated decline in the size of the DNA-containing species which can be extracted from unirradiated cells. The latter effect may reflect normal aging of the cerebellum.


Characterization of a protein species isolated from HeLa cell cytoplasm by affinity chromatography on polyadenylate-sepharose. Chromatography of different soluble extracts from HeLa cells on poly(A)-Sepharose columns has allowed the isolation of a protein fraction eluted by 0.2 M NaCl and localized predominantly in the cytoplasmic supernatant and in the 0.5 M KCl ribosomal wash. This fraction is present in large amounts (around 3% of total cytosolic proteins) and appears to contain a major protein species that is acidic on electrofocusing (pI around 4.5) and phosphorylated. It runs on glycerol gradients and Sephadex G-200 chromatography close to the aldolase marker (158,000 daltons) and dissociates into apparently identical subunits of 38,000 +/- 2,000 daltons on sodium dodecyl sulfate-acrylamide gels, suggesting a tetrameric structure.


A neurohypophyseal hormone analog with selective oxytocin-like activities and resistance to enzymatic inactivation: an approach to the design of peptide drugs. Stepwise, synthetic alteration of oxytocin, guided by conformational and enzymological considerations, has led to analogs with specifically modified activity profiles and resistance to enzymatic inactivation. General requirements for the design of peptides with therapeutic value are discussed.


Activation of sea-urchin eggs by a calcium ionophore. Micromolar amounts of the divalent ionophore A23187 can activate echinoderm eggs. The activations by ionophore A23187 were examined in terms of membrane elevation, the program of membrane conductance changes, the respiratory burst, and the increases in protein and DNA synthesis which normally accompany activation by sperm. In all these respects activation by the ionophore was fairly normal although subsequent cleavage and embryonic development was limited. Ionophore A23187 activations of the cortex of Lytechinus pictus and Strongylocentrotus purpuratus eggs were compared in various ionic media and were found to be completely independent of the ionic composition of the external solution. Respiration and protein synthesis of L. pictus eggs in singly substituted ionic media also indicated that these activations were independent of external sodium, calcium, or magnesium. These results suggest that the ionophore acts by releasing intracellular Ca(++). Consistent with this interpretation is the finding that eggs preloaded with (45)Ca show a 20-fold increase in (45)Ca-efflux when activated by ionophore A23187 or fertilization. Measurements of the "free" and "bound" calcium and magnesium in homogenates of the unfertilized eggs show that most of the Mg(++) is already available in the soluble form, whereas Ca(++) is sequestered but available for release. We propose that both normal fertilization and ionophore activation affect the metabolism of the egg by releasing Ca(++) sequestered in intracellular stores.


Generation of specific repeated fragments of eukaryote DNA. Calf-thymus DNA, hydrolyzed with a site-specific endonuclease from Haemophilus influenzae Rd, yields 12 discrete bands on polyacrylamide-agarose gels. These range in size from 7.5 x 10(4) to 2 x 10(6) daltons, and they represent about 5% of the total DNA with individual fragments comprising 0.1-1.5%. The various DNA segments are repeated between 1500 and 220,000 times per haploid genome. Whereas the wide range of reiteration frequencies suggests different origins for some of the fragments, the bias in fragment densities in CsCl and in Ag(+)-Cs(2)SO(4) toward those of known satellite DNAs suggests similar origins for some of them. Models for the possible origin of the DNA fragments can be grouped into three distinct, experimentally distinguishable, classes.


Are recommended daily allowances for vitamin C adequate? Recommended daily allowances, U.S.A., for ascorbic acid are several times the minimum daily requirement of about 10 mg to prevent clinical symptoms in adults. The recommended daily allowances reflect the levels of ascorbic acid required to produce tissue saturation in human beings, so that higher doses are promptly excreted in the urine. In various investigations, responses to ascorbic acid were not obtained under conditions where the intake was considerably lower than the recommended daily allowances, but higher than the level needed to prevent clinical symptoms of ascorbic acid deficiency. The human ascorbic acid requirement cannot be calculated by a linear extrapolation from guinea pigs per kg of body weight because guinea pigs are much smaller than human beings and, hence, their metabolism is more rapid per unit of body weight. Evolutionary loss of ascorbic-acid-synthesizing ability may be a neutral change that was incorporated by genetic drift.


Proton nuclear magnetic resonance investigations and ring current calculations of guanine N-1 and thymine N-3 hydrogen-bonded protons in double-helical deoxyribonucleotides in aqueous solution. Methods are outlined for assigning the guanine-N(1)H and thymine-N(3)H protons to particular base pairs in the proton nuclear magnetic resonance spectra of double-stranded oligodeoxyribonucleotides of known sequence in aqueous solution. Ring current calculations have been used to evaluate the upfield shifts of the guanine-N(1)H and thymine-N(3)H protons from the pyrimidine and purine rings of nearest-neighbor base pairs in DNA B-type double-helical structures. Chemical shifts of 13.6 +/- 0.1 ppm and 14.6 +/- 0.2 ppm are assigned to the guanine-N(1)H proton of an isolated G.C base pair and the thymine-N(3)H proton of an isolated A.T base pair, respectively.