Effect of asphyxia due to umbilical cord occlusion in the foetal lamb on leakage of liquid from the circulation and on permeability of lung capillaries to albumin. 1. Experiments were performed on foetal lambs, exteriorized at Caesarean section, to determine the effects of asphyxia on the leakage of liquid from the circulation and on the permeability of lung capillaries to albumin. Following a period of control observation (30-120 min) the foetus was asphyxiated by occlusion of the umbilical cord for 5-10 min and then allowed to recover while observations were continued for a further 20-80 min.2. Measurements were made of the lymph flow from the lungs, that had drained via the thoracic duct; of protein concentration in lymph and plasma; of arterial blood haematocrit, pH, P(O2) and P(CO2); and of arterial and left atrial pressures and heart rate. Human serum albumin labelled with (125)I was infused intravenously during the control period and (125)I count rates were followed in plasma and lymph throughout the experiment. Values for the transfer coefficient of albumin (E/V min(-1), i.e. interstitial fluid clearance of albumin per unit of lung interstitial fluid volume) were determined during control, cord-occlusion and post-occlusion periods.3. During cord occlusion arterial and left atrial pressure, haematocrit and plasma protein concentration all rose, returning to the control value by 20 min after release of cord occlusion. The haematocrit values indicated that about 9% of the blood volume was temporarily lost from the circulation. Lung lymph flow also increased, reaching a maximum in the 5 min period after release of occlusion and returning to the control level 15 min later. Values for E/V of albumin were at no time significantly different from those during the control period.4. It was concluded that acute foetal asphyxia produced by umbilical cord occlusion caused an increased leakage of liquid from the circulation in general. This effect was temporary and was probably due to an increase in capillary pressure during cord occlusion. The asphyxia had no persistent effect on the permeability of lung capillaries to albumin.


The binding of tritiated ouabain to mammalian non-myelinated nerve fibres. 1. A study has been made of the binding of radioactively labelled ouabain by desheathed rabbit vagus nerves, which consist mainly of non-myelinated fibres. The corresponding inhibition of the electrogenic sodium pump was also measured.2. By varying the ouabain concentration and the external potassium concentration two kinds of binding sites could be distinguished: a first site specifically associated with pumping and whose ability to bind ouabain is dependent on the external presence of potassium; and a second site not associated with pumping and unaffected by external potassium.3. Just complete inhibition of the sodium pumping mechanism is associated with a specific binding of ouabain of about 4.3 p-mole/mg dry nerve.4. This gives an upper limit for the density of sodium pumping sites of about 750 per square micron.5. The turnover rate (i.e. (cation pumped)/(number of sites)) at 20 degrees C is about 22 sec(-1).


On the degeneration of rat neuromuscular junctions after nerve section. 1. A study was made of functional and structural changes during degeneration of end-plates in the rat diaphragm after phrenic nerve section at two levels.2. For 8-10 hr after cutting the nerve in the neck, all end-plates retain the ability to transmit impulses. During the following 8-10 hr, an increasing number of end-plates lose this ability so that after a total of about 20 hr, no end-plates can transmit.3. Transmission failure occurs abruptly at most end-plates. This failure is usually accompanied by cessation of spontaneous miniature end-plate potentials (min.e.p.p.s), though in a few cases min.e.p.p.s persist after junctional transmission has failed. Several degenerating junctions were observed where the frequency of min.e.p.p.s was very low, suggesting an intermediate stage in min.e.p.p. failure.4. The time of junctional failure depends on the length of the degenerating nerve stump. For each additional centimetre of nerve, failure is delayed about 45 min.5. Changes in ultrastructure of nerve endings closely parallel those of function. For about 8-12 hr after cutting the nerve, nearly all end-plates appear normal. During the period when transmission is failing, some end-plates are clearly undergoing structural break-down. By the time functional failure is complete, all end-plates appear grossly abnormal.6. During degeneration, the contents of the axoplasm undergo disruption and the nerve terminal breaks up into small fragments. In contrast, the Schwann cell appears to become very active and its processes extend into the synaptic cleft to surround fragments of the nerve terminal. Ultimately, the Schwann cell completely replaces the axon at the end-plate.7. Increasing the length of the peripheral nerve stump delays the onset of structural break-down. Disruption of end-plates near the site of nerve entry into the muscle occurs before those farther away.8. It is suggested that end-plate degeneration is triggered by a signal which passes from the site of injury to the nerve terminal. The duration of the period after transection when end-plates appear to be normal would then reflect the time required for this signal to travel the length of the isolated nerve stump.


Action of kinins on salivary myoepithelial cells. 1. Bradykinin and kallidin were injected close-arterially into the submaxillary glands of dogs and the effects on the pressure in the salivary ducts were recorded.2. Both kinins in very low dosage (threshold about 0.001 mug/kg) caused a pressure rise in the salivary duct without eliciting any salivary secretion, indicating that they produced contraction of the salivary myoepithelial cells.3. This effect was obtained even after administration of atropine, dihydroergotamine and propranolol.


On the relationships between membrane potential, calcium transient and tension in single barnacle muscle fibres. 1. The calcium-sensitive photoprotein aequorin has been used to follow the rapid changes in intracellular calcium concentration that occur during the contraction of single muscle fibres from the barnacle Balanus nubilus, Darwin.2. The transient change in calcium-mediated light emission (calcium transient) and the changes in membrane potential and tension were recorded simultaneously, thus permitting an examination of the relationships between the chemical, electrical, and mechanical events of excitation-contraction coupling.3. With short-duration stimuli (< 200 msec), the calcium transient shows an S-shaped rising phase reaching a maximum soon after the cessation of the stimulus pulse. During membrane repolarization the calcium transient begins an exponential falling phase which has a time constant of 50-80 msec at 11-12 degrees C.4. The shape of the calcium transient resembles the first derivative of the rising phase of the isometric tension response, thus suggesting that calcium controls the rate of tension development.5. There is no detectable increase of the light emission above resting values, during the falling phase of isometric tension.6. A plot of the calcium transient area (lumen x sec) versus peak isometric force (g. cm(-2)) is linear over, at least, a range of forces from ca. 50-400 g. cm(-2).7. When the fibre is capable of producing an active membrane response following the intracellular injection of potassium citrate, the onset and cessation of the calcium transient follow closely the onset and cessation of the active membrane response. Tension responses under these conditions are much suppressed, suggesting that excitation-contraction coupling may be partially blocked between calcium release and the development of tension.8. Hypertonic salines (1 M sucrose or 1 M glycerol) cause little change in the membrane response, but greatly suppress the calcium transient and completely abolish the tension responses. These effects are readily reversible when normal saline is reintroduced, suggesting that excitation-contraction coupling may be temporarily blocked between the membrane response and calcium release.9. If the stimulus is prolonged (> 250-300 msec), the calcium transient falls slowly from its maximum value despite continued membrane depolarization, suggesting a time-dependent change in the ratio of the rate of release of calcium to the rate of calcium binding. The results from brief tetanic stimulation also support this suggestion.


The effects of some inhibitors and accelerators of sodium transport on the turnover of 22Na in the cerebrospinal fluid and the brain. 1. The purpose of the experiments was to discover whether the turnover of (22)Na in the c.s.f., which is largely determined by its rate of secretion, is affected in the same manner by inhibitors or accelerators of active transport as the turnover in the brain tissue since there is reason to believe that the composition of the extracellular fluid of brain is controlled by active processes.2. Although acetazolamide (Diamox) inhibits rate of secretion of c.s.f. and the turnover of (22)Na in this fluid it does not appreciably affect the turnover of (22)Na in the brain tissue of either rat or rabbit, the small inhibition observed being probably secondary to the effects on the c.s.f.3. Ouabain inhibits secretion of c.s.f. and turnover of (22)Na in this fluid, but it, also, has no effect on turnover of (22)Na in the brain tissue alone or in combination with Diamox.4. Amphotericin B and amiloride, the anti-aldosterone spirolactone S.C. 114266, all inhibited secretion of c.s.f. without affecting turnover of (22)Na in the brain tissue; actinomycin D, puromycin and cycloheximide, however, had no effect on secretion of c.s.f.5. Vasopressin inhibited secretion of c.s.f. and turnover of (22)Na in this fluid but increased the turnover in the brain by some 16%.6. In the ventriculo-cisternally perfused rabbit, replacement of 80% of the NaCl in the perfusion fluid by choline chloride caused a slowing of the passage of (22)Na from blood into the perfusion fluid.7. On the basis of these results it is concluded that the brain extracellular fluid is not renewed by appreciable bulk-flow, in contrast with the c.s.f.


The representation of three-dimensional visual space in the cat's striate cortex. 1. Binocularly driven single units were recorded in the cat's striate cortex. For each neurone the two monocular receptive fields were stimulated simultaneously in order to assess the optimal positioning of the image in both eyes to give the best binocular response.2. The electrode was driven perpendicular to the surface of the brain to explore cortical columns, all the cells of which are known to have the same preferred target orientation.3. All orientation columns were found to fit into one of two classes according to their binocular organization.4. In a constant depth column the receptive fields of binocular neurones cover a small retinal area and they are laid out in almost identical arrays in the two eyes. Consequently, the horizontal disparity is practically the same for all the units. The depth column as a whole is viewing a thin sheet of visual space, a few degrees wide, floating at some distance from the cat. There may be about 0.6 degrees disparity difference between neighbouring depth columns.5. In a constant direction column the binocular units' fields are all super-imposed on the retina contralateral to the hemisphere containing the column. In the ipsilateral eye they are more scattered horizontally. Therefore the horizontal disparity varies enormously from cell to cell and the column as a whole is viewing a cylinder of visual space directed towards the contralateral eye. Neighbouring direction columns may vary by about 4 degrees in their oculocentric visual direction.6. This columnar arrangement is probably important for space perception in the cat. Activity in only one depth and one direction column would specify the orientation and the three-dimensional locus of an object in space.7. The two types of column may be involved in the control of disjunctive and conjugate eye movements.


Miniature potentials in denervated slow muscle fibres of the frog. 1. Pyriformis and iliofibularis muscles of the frog were studied with micro-electrodes. Both muscles contain a mixture of fast and slow muscle fibres, which can be distinguished by differences in their miniature end-plate potentials (min.e.p.p.s).2. In addition, the membrane time constant of fast fibres is < 20 msec, while that of slow fibres is > 200 msec.3. The characteristic difference in time constant persisted after denervation and allowed the identification of fibre type.4. Denervated slow fibres had min.e.p.p.s of variable time courses and skew amplitude distributions. Their frequency was lower than in normally innervated fibres, and could be increased by hypotonic solutions.5. In analogy with similar observations made previously in fast muscle fibres, it is suggested that after nerve degeneration the Schwann cells of small motor nerve fibres release packages of transmitter which give rise to min.e.p.p.s.


Diffusion and distribution of dimethyl sulphoxide in the isolated guinea-pig taenia coli. 1. The diffusion of the cryoprotective non-electrolyte dimethyl sulphoxide (DMSO) in the isolated guinea-pig taenia coli at 37, 25 and 0 degrees C has been studied using [(35)S]DMSO.2. Within 1 hr after immersion at 37 degrees C in Krebs solution containing 20% (w/v) DMSO and trace amounts of [(35)S]DMSO, the non-electrolyte was distributed uniformly throughout a volume equivalent to the total initial water content of the muscle.3. The kinetics of efflux of [(35)S]DMSO from muscles at constant volume were analysed on the basis of two models: one incorporated radial diffusion in extracellular fluid with simultaneous permeation into the cells, the other involved only radial diffusion in homogeneous cylinders of tissue having no internal barriers to diffusion; the former was found to give a better representation of the efflux kinetics.4. If it was assumed that the rate of diffusion of DMSO in the extracellular space of taenia coli was the same as that in the bathing medium, the values of the extracellular space and the permeability of smooth muscle to DMSO, obtained from the analysis of the efflux kinetics, were 454 +/- 19 ml./kg and 2.36 +/- 0.05 x 10(-6) cm sec(-1) at 37 degrees C.5. The activation energy for the transfer of DMSO across the surface of the cell was estimated to be 6.0 kcal/mole at 37 degrees C, 6.6 kcal/mole at 25 degrees C and 11.6 kcal/mole at 0 degrees C, indicating either that the equivalent pore radius of the cells decreased with temperature or that the cell permeability represented the sum of two fluxes, one through the aqueous pores of the cell and the other through the lipid phase of the cell membrane, each with a different energy of activation.6. A net flux of water across the surface of the cells, superimposed on the efflux of DMSO, markedly affected the rate of diffusion of the non-electrolyte out of the whole tissue; however, it was considered that an analysis of the efflux kinetics was not possible under these conditions.7. These results provide a basis for methods which will be used to investigate the possibility of preserving tissue in unfrozen aqueous media at sub-zero temperatures.


Heterosynaptic facilitation and post-tetanic potentiation in Aplysia nervous system. 1. Heterosynaptic facilitation was defined as an increase of amplitude of a test excitatory post-synaptic potential (EPSP) after the activation of a pathway (heterosynaptic pathway) different from that which produced the test EPSP. This phenomenon has been studied in Aplysia central nervous system under conditions which excluded the participation of post-tetanic potentiation.2. A unitary test was produced in the left and right giant cells, by indirect stimulation of an interneurone located in the peri-oesophageal ring.3. During heterosynaptic stimulation, orthodromic and antidromic activation of the test interneurone was prevented by (1) isolating the synaptic afferent region of the test interneurone from the tested synapse on the right giant cell by a sucrose block applied on the left pleurovisceral connective, and (2) using physiological stimulation of a piece of skin as a heterosynaptic stimulus. Under these conditions which prevented any firing in the test interneurone, heterosynaptic facilitation is observed as a 200% increase of amplitude of the test EPSP in the right cell which lasted more than 15 min. When instead of the physiological stimulus a supramaximal electrical stimulation of the nerves afferent to the abdominal ganglion was used, the increase of amplitude of the test EPSP could reach as much as 500% of its original amplitude. The effectiveness of such heterosynaptic stimulus was smaller when it was applied in the absence of a block of the left pleuro-visceral connective.4. It was possible to produce heterosynaptic facilitation when the preparation was cooled to 7-9 degrees C or if Li(+) replaced Na(+) in the medium. Both of these changes suppressed post-tetanic potentiation.5. It was concluded that heterosynaptic facilitation is a phenomenon different from post-tetanic potentiation. Heterosynaptic facilitation is similar to heterosynaptic inhibition seen in other cells in the same preparation, except for the polarity of action. Both phenomena seem to result from comparable mechanisms, probably acting on the quantity of transmitter released.


The differential effects of tetraethylammonium and zinc ions on the resting conductance of frog skeletal muscle. 1. The effects of tetraethylammonium (TEA) and zinc ions on the resting conductance of frog muscle were examined using a method which permitted control of the membrane potential near the end of a muscle fibre and measurement of an approximation of the membrane current.2. TEA reduced the amplitude of the inactivating inward current obtained on hyperpolarizing, both when this was measured as initial current [I(m)(0)] less the estimated chloride current and as [I(m)(0) - I(m)(infinity)]. 115 mM-TEA reduced the amplitude of [I(m)(0) - I(m)(infinity)] by about 85%.3. TEA had little effect on the time constant with which the inward potassium currents inactivated. This finding appeared to be in conflict with the view that the inactivation is due to depletion of potassium from the T-system, though the results in standard Ringer were in good agreement with such an hypothesis.4. In the standard chloride Ringer, the resting membrane resistance was 3530 Omega cm(2). 115 mM-TEA increased this 1.6 times to 5580 Omega cm(2).5. The effect of TEA on voltage-current relations obtained in high K(2)SO(4) solutions was also examined. With large pulses, the voltage-current relations in TEA and control solutions tended to become linear. This linear part could be extrapolated and subtracted from the voltage-current relation.6. TEA, at a concentration of 150 mM, reversibly reduced by 88% the amplitude of the currents obtained during both depolarizing and hyperpolarizing pulses; this figure was obtained after subtraction of the linear part of the relation, which was itself unaffected by TEA and which represented a resistance of 5600 Omega cm(2).7. The reductions in the inactivating potassium current and in the current flowing through the inwardly rectifying potassium channel in high K(2)SO(4) solutions fit, fairly closely, a concentration-effect relation for TEA with a dissociation constant of 20 x 10(-3)M.8. Also investigated were the slow time-dependent changes in membrane potential occurring when [K](o) is altered from 2.5 to 10 mM at constant chloride (120 mM). The findings were consistent with the view that TEA reduced the potassium conductance without much effect on the chloride conductance. In particular, when muscles equilibrated for 1 hr in 10 mM-K Ringer were returned to 2.5 mM-K, the initial rate of repolarization was reduced, even though the driving force on K was slightly larger than in the control experiment.9. Zinc ions appeared to be without effect either on the amplitude of the inactivating potassium current obtained when square hyperpolarizing pulses were applied to the fibre membrane, or on its time constant.10. In standard Tris-buffered Ringer, the membrane resistance was 3350 Omega cm(2). Zinc Ringer (2.5 mM) increased this rather more than twice to 6830 Omega cm(2).11. It is concluded that the two agents, TEA(+) and Zn(2+), which both reduce delayed potassium currents in muscle, act in different ways on the resting conductance of frog muscle.


The effect of the tetraethylammonium ion on the delayed currents of frog skeletal muscle. 1. A method which permitted control of the membrane potential near the end of a muscle fibre and measurement of an approximation of the membrane current was used to investigate the effects of the tetraethylammonium (TEA) ion on the delayed outward potassium current obtained on depolarizing.2. Assuming R(i) to be 250 Omega cm and a fibre diameter of 80 mu, the mean value for the maximum potassium conductance (g(K)) was 23.2 +/- 3.2 mmho.cm(-2).3. 58 mM-TEA, in two series of experiments, reduced g(K) by about 90%. A concentration-effect relation for TEA in its action on the delayed rectifier could be fitted by a curve for a drug-receptor complex assuming one molecule of TEA to combine reversibly with one receptor, and a dissociation constant of 8 x 10(-3)M.4. TEA tended to shift the threshold for delayed rectification to slightly more negative membrane potentials. TEA caused a similar shift in the relation between n(infinity) and membrane potential, but did not much alter the form of the relation.5. The relation between n(infinity) and membrane potential and between tau(n) (-1) and membrane potential were well fitted by the model of Adrian, Chandler & Hodgkin (1970a) assuming that the Q(10) was 2.5.6. TEA slowed the rate of onset of the delayed potassium currents, decreasing tau(n) (-1) (the reciprocal of the time constant of the fourth power function which described the current's development) by about 80%.7. The inactivation of the delayed current with time was shown to follow a complex time course. A fast phase decays with a time constant of 270 msec and a slow phase with a time constant of 2.3 sec at a membrane potential of + 10 mV.8. The fast phase of the delayed current is much more susceptible to the action of TEA than the slow phase, and these are interpreted in terms of different potassium channels. TEA has little effect on the time constant with which either the fast current or the slow current inactivates.


The effect of the internal sodium concentration on calcium fluxes in isolated guinea-pig auricles. 1. Calcium efflux from guinea-pig auricles followed saturation kinetics when [Ca](o) and [Na](o) were changed while the ratio [Ca](o)/[Na](o) (2) was kept constant. The Michaelis constant, K(m) (Ca+Na) = 40 mM, suggests that a hypothetical carrier system, responsible for sodium-calcium exchange, is far from saturation with the inside concentrations of these ions.2. [Na](i) was altered in the auricles between 12.5 and 60 mM/kg fibre water while total cellular calcium concentration ([Ca](t)) at the beginning of the influx period was not significantly different in the various groups of preparations.3. (45)Ca influx increased appreciably with increasing [Na](i). (45)Ca influx from sodium-poor solution corresponded to an almost equal increase in [Ca](t), while [Ca](t) did not change much in preparations loaded with (45)Ca in Tyrode solution. When the sodium-activated fraction of calcium influx was plotted against [Na](i) (2) the resulting curve indicated saturation with K(m) (Na) = 3500 (mM [Na](i))(2) and maximal influx rate, J(i, max) (Ca') = 1.35 mM/kg wet weight x 10 min.4. When the preparations were re-equilibrated for various times in normal Tyrode solution after [Na](i) had been increased, both the sodium-activated component of calcium influx and [Na](i) (2) decreased with approximately the same rate constants.5. Calcium efflux from auricles with high [Na](i) was increased when it was measured in Tyrode solution while the efflux in sodium-poor solution was inhibited.6. Auricles with increased [Na](i) showed a positive inotropic contractile response.7. The main conclusion reached by these experiments is that calcium influx is affected by [Na](i) in a way which is compatible with a carrier-mediated sodium-calcium exchange system.


Further purification of a polypeptide demonstrating enterogastrone activity. 1. The further purification of a polypeptide having potent enterogastrone activity, without CCK-PZ effects, is described.2. The material was inhibitory when doses of 1.0 mug/kg.hr were administered intravenously. Amino acid analyses demonstrated the absence of proline, a high content of glutamine and a preponderance of lysine over arginine. Tryptic degradation destroys the inhibitory effect of the polypeptide. Further studies must be performed before the physiological status of the polypeptide can be ascertained.


Cervico-lumbar reflex interactions involving a proprioceptive receiving area of the cerebral cortex. 1. In the decerebrate cat descending cervico-lumbar reflex interactions from neck muscle nerves are absent, and those from forepaw nerves are reduced or absent.2. Lesions restricted to the anterior pole of the suprasylvian gyrus regularly abolish descending cervico-lumbar reflex interactions from neck muscle nerves. The same lesions may reduce or abolish descending cervico-lumbar reflex interactions from forepaw nerves.3. The ascending cortical looping pathway utilized in descending cervico-lumbar reflex interactions is crossed, and the descending pathway from the cerebral cortex is bilateral.


Suprathreshold spectral properties of single optic tract fibres in cat, under mesopic adaptation: cone-rod interaction. 1. Responses of 122 on-centre or off-centre ganglion cells in cat to suprathreshold monochromatic stimulation have been analysed under mesopic adaptation with white light, recording from their single fibres in the optic tract at a level posterior to the chiasma. Fields described are monocularly driven, located in the right half-fields of either eye, and are all within 30 degrees of the area centralis.2. Retinal receptors are of two types, viz. 556 nm cones and 502 nm rods. At high mesopic adaptation (1 log cd/m(2)) all units receive mixed cone-rod input. Under low mesopic adaptation (0 log cd/m(2)) the great majority receive mixed input; a few receive pure rod input. These results are in agreement with the threshold data (Andrews & Hammond, 1970).3. Peaks of spectral response curves of units, to suprathreshold monochromatic stimuli of different wave-length but equal quantum flux, fall primarily between 550 and 560 nm for high mesopic adaptation, and between 500 and 520 nm for low mesopic adaptation. Peak position depends on the degree of rod or cone contamination, in units treated under high or low mesopic levels respectively.4. Units with cone-rod input to the field centre receive similar but antagonistic cone-rod input to the surround. In units with pure rod input to the field centre, only rods input to the surround.5. Cone and rod components of on-centre discharges are identifiable in terms of colour sensitivity and latency. The cone component is primarily a short-latency, high-frequency, excitatory transient; the rod component is a longer latency, lower frequency, maintained phase of excitation.6. Less direct evidence indicates that cone and rod input to the field surround give rise to inhibitory components of comparable latency, magnitude and time course.7. The identified cone and rod components of responses are used in further experiments to show that cone and rod input have different spatial organization both in the receptive field centre and in the surround.8. The boundary between the field centre and surround for rods has a diameter on average about twice as large as that for cones. This organization is such that the field centre for rods substantially overlies the cone surround.9. Changes in receptive field organization occur within the mesopic range, associated with the changeover from cone to rod vision.10. It is suggested that the difference between cone and rod input in the mesopic range may form the basis of the cat's ability behaviourally to discriminate between colours.


Non-cholinergic nature of the post-ganglionic motor neurones in guinea-pig bladder.


Mesopic increment threshold spectral sensitivity of single optic tract fibres in the cat: cone-rod interaction. 1. Mesopic increment threshold spectral sensitivities of sixty-six on-centre and twenty-five off-centre ganglion cells in the cat were determined by recording from single fibres of the left optic tract at a level posterior to the optic chiasma.2. All units were monocularly driven; receptive fields were located almost exclusively in the right visual half-fields within 30 degrees of the area centralis, but with slight overlap across each retinal mid line to the left half-fields. The extent of field spread to the right temporal hemi-retina was significantly larger than that to the left nasal hemi-retina. Field centre diameters ranged from less than 0.25 degrees for central units to 2 degrees for more peripheral units.3. At high mesopic adaptation of 1 log cd/m(2) all responsive units (forty-four fibres) received mixed cone-rod input. Threshold curves could always be fitted by the absorption spectra of visual pigment 556 together with varying contributions from visual pigment 507, each derived from the Dartnall nomogram.4. Of forty-seven fibres analysed under low mesopic background (0 log cd/m(2)) 92% received similar cone-rod input, being fitted predominantly by visual pigment 507 with slight cone contamination. The remaining 8% received pure rod input and could be matched by visual pigment 507 alone.5. In conclusion, the cat retina presumably contains a single class of cones with absorption maxima at 556 nm, and a single class of rods. Discrepancy between the presumed rod absorption maximum (502 nm) and the low-mesopic sensitivity maxima of tract fibres (507 nm) is considered in terms of tapetal reflectivity, and absorption by ocular media. Both mechanisms input to the great majority of retinal ganglion cells. At high mesopic levels the cone mechanism predominates. At low mesopic levels the rod mechanism predominates. A small proportion of ganglion cells within the central 30 degrees of the retina receive input only from rods, and in these the rod mechanism saturates completely below 1 log cd/m(2).


Bier's spots--evidence that they are mediated by an intravascular venoconstrictor substance.


A gated stimulator of modular construction.


Intensity variation of inhibition of photosynthesis by photosystem II inhibitors.


The collection of rat urine free of faecal contamination.


The secretory parasympathetic innervation of the parotid gland of the dog.


Ultrastructure of aortic body tissue in the cat.


An apparatus for the automatic extraction of cell parameters from microscope slide preparations.


Radio-immunoassay of human placental lactogen.


Reflex vasomotor responses elicited from the carotid sinus and aortic  arch baroreceptors: comparison of pulsatile and non-pulsatile pressures.


Ultrastructure of urinary bladder of Rana cancrivora.


Muscle receptor properties in the crab.

Muscle receptor properties in the crab.


The role of oxygen-linked carbamate in the transport of CO2 by human erythrocytes under physiological conditions.


Influence of saline diuresis on urinary and renal medullary responses to lysine vasopressin infusion in the rat.


Possible effect of a vegan diet upon lung function and the cardiorespiratory response to submaximal exercise in healthy women.


The effects of luminal nutrition on the transintestinal potentials and short-circuit currents associated with active hexose transfer across the small intestine.


Dopamine in adipose tissue of the ox and the effect of dopamine infusion on plasma unesterified fatty acids.


Oscillatory transients in the response to an abrupt change of force at the wrist in Parkinsonism.


The effect of acidaemia on the increase in heart rate from stimulation of the left atrial receptors in the dog.


Sweat discharge in Welsh Mountain sheep.


The effect of cocaine on the noradrenaline overflow from the isolated blood-perfused cat spleen.


Oestradiol-binding macromolecules in the hypothalamus.


Sensitivity of foetal and new-born rat diaphragm to insulin.


Factors affecting the release of enzymes from the isolated perfused rat heart.


Anion and cation currents in pigeon cones.


Transport of glutathione across the small intestine of the rat in vitro.


The in vitro assay of pituitary MSH.

The in vitro assay of pituitary MSH.


Pattern transformation by neural nets.

Pattern transformation by neural nets.


An electrically controlled thermal stimulator.


The use of operant techniques for modifying the behavior of the severely and profoundly retarded. II. The techniques.


Employment satisfaction of previously institutionalized mentally subnormal workers. Elwyn Institute.


A simple, adaptable drinking device for mental retardates lacking arm-hand control (pilot project).


Toilet training for profoundly retarded with a limited staff. Sunland Training Center at Miami.


Serum thyroxine.

Serum thyroxine.


Endocrine regulation of reproduction.

Endocrine regulation of reproduction.


Hypergammaglobulinemia.

Hypergammaglobulinemia.


Squamous cell carcinoma of the oral cavity.


Coronary detours.

Coronary detours.


Hypoxia, hypercarbia and respiratory acidosis.


Short cuts in tuberculosis care?

Short cuts in tuberculosis care?


Decreased incidence of thyroiditis in aged Buffalo strain rats given 3-methylcholanthrene.


The effect of GSR confirmed perception of bisensory input on immediate verbal memory.


Instrumental modification of the GSR.

Instrumental modification of the GSR.


Quantification of the REM sleep cycle as a rhythm.


Relationships among responses in the human newborn: the non-association and non-equivalence among different indicators of responsiveness.


Square-wave analysis of skin impedance.

Square-wave analysis of skin impedance.


Evoked potential averager made up from laboratory instruments.


Transducer bridge amplifier to directly drive low sensitivity oscillographic recorders.


Detachable lead holder for human subjects.


Apparatus and technique for work with the curarized rat.


Serratia marcescens sepsis.

Serratia marcescens sepsis.


Dogmatism and attitudes towards the Vietnam war.


One thousand consecutive cases of major facial injury.


Effects of social reinforcement on health reporting in the household interview.


Reputation and self-evaluation as determinants of attractiveness.


Quantitative in vitro measurement of endotoxin in plasma.


Consistent and inconsistent status characteristics and the determination of power and prestige orders.


Status inconsistency and self-evaluation.


Progress in the management of intestinal fistulae.


Recognition of postoperative myocardial infarction: value of the CPK.


Effects of gastrointestinal hormones on serum immunoreactive insulin and insulin-like activity in normal and pancreatectomized dogs.


Cardiac preservation.

Cardiac preservation.


The role of circulating lymphocytes and lymphoid tissues in graft-versus-host reactions.


Disabling injuries by type of accident.

Disabling injuries by type of accident.


Longevity of members of Congress.

Longevity of members of Congress.


Leiomyoma of the esophagus.

Leiomyoma of the esophagus.


Renal function immediately after contralateral nephrectomy: relation to the mechanism of compensatory kidney growth.


The effects of a cobra venom factor and ethyl palmitate on the prolongation of survival of heterologous erythrocytes.


Experimental pyelonephritis. XVI. Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus infections in mice and the effect of "water diuresis".


The synthesis of the branched-chain fatty acids of rat skin surface lipid.


The branched-chain fatty acids on rat faecal lipids. The contribution of the intestinal microorganisms.


Insulin responsiveness and lipid synthesis in human fat cells of different sizes: effect of the incubation medium.


Lipid metabolism in inositol-deficient yeast, Saccharomyces carlsbergensis. I. Influence of different carbon sources on the lipid composition of deficient cells.


A two-dimensional thin-layer chromatographic system for phospholipid separation. The analysis of yeast phospholipids.


Lipid metabolism in inositol-deficient yeast, Saccharomyces carlsbergensis. II. Incorporation of labeled precursors into lipids by whole cells and activities of some enzymes involved in lipid formation.


Phospholipid metabolism during development of the brine shrimp Artemia salina. I. Incorporation of cytidine 5'-phosphate into cytidine diphosphate choline by a microsomal enzyme system.


Phospholipid metabolism during development of the brine shrimp Artemia salina. II. Synthesis of phosphatidyl choline by a microsomal enzyme system from nauplii.


Effects of intraductal administration of prolactin, actinomycin D and cycloheximide on lipoprotein lipase activity in the mammary glands of pseudopregnant rabbits.


Microbial hydroxylations. VII. Kinetic studies on the hydroxylation of 19-norsteroids by Curvularia lunata.


Microbial hydroxylations. 8. Induction of steroid hydroxylases of Curvularia lunata by 19-nortestosterone analogs.


Quantitative relationship between adrenal cytochrome P-450 and its reducing system, and their organ specificities in relation to corticoidogenesis.


Biosynthesis of prostaglandins E2 and F2-alpha from tritium-labelled arachidonic acid by rat stomach homogenates.


Physical studies of aqueous solutions of two prostaglandins.


Production of lecithin: cholesterol acyltransferase by the isolated perfused rat liver.


A simple method for preparation of methyl-labelled (-) carnitine.


Induced synthesis of cyclopropane fatty acid synthetase in Pseudomonas fluorescens.


Occurrence of phosphonolipids in mycobacteria.


Decrease in rate of ATP synthesis of isolated rat heart mitochondria induced by dietary erucic acid.


Metabolite transport in mitochondria: an example for intracellular membrane function.


The two faces of the inner mitochondrial membrane.


Lactose synthetase: evolutionary origins, structure and control.


The structure, function and control of glycogen phosphorylase.


A colorimetric method for the analysis of sulphonates.


Oxygen in corneal vascularisation.

Oxygen in corneal vascularisation.


Observation on the bacteriostatic property of extract of Tamarindus indica leaf (TIL). 2.


Clinical evaluation of rat tail tendon sutures.


Styles and refractive errors. Their aetiological relationship.


Refractive errors in full-term newborn babies.


Dacryocystorhinostomy with preparation of a horizontally oval bony ostium.


Sympathetic keratitis presumably herpetic.


Congenital unilateral pigmentary retinal degeneration with myasthenia gravis.


The effects of nutritional deprivation on the subsequent productivity of sheep and cattle.


Metabolic changes during Eperythrozoon infection in cattle.


Pathogenic properties of Escherichia coli enterotoxin after parenteral administration to pigs, rabbits and mice.


Agglutinating and complement-mediated activities of sheep antisera, IgM, slow and fast gamma-globulin antibodies.


Some aspects of drug persistence in domestic animals.


The effect of anthelmintic treatment on the development of resistance to Trichostrongylus colubriformis in sheep.


Acute selenium toxicity in lambs following intramuscular injection of sodium selenite.


Observations on ovarian transplants in the domestic fowl and their bearing on normal ovarian function.


Relationship between metabolism-inhibiting antibodies and colonial growth of Mycoplasma hyorhinis and other porcine mycoplasma in the presence of rabbit and pig sera.


Ultrastructural studies of the normal pulmonary tissue of the pig.


Immunological studies of Mecistocirrus digitatus infection in calves.


The inactivation of Erysipelothrix rhusiopathiae in pig buffy-coat leucocytes.


Sporidesmin poisoning in sheep. The effects on lipid and bile acid metabolism as reflected in serum.


The production of haemoglobin C by sheep at simulated high altitude.


The efficacy of 5-isopropoxy-carbonylamino-2-(4-thiazolyl) benzimidazole against helminths of sheep.


Studies of the microclimate of the external auditory canal in the dog. I. Aural temperature.


Cytopathogenicity and neutralization of goatpox virus in cell culture.


Studies of the microclimate of the external auditory canal in the dog. II. Hydrogen ion concentration of the epithelial surface of the external auditory meatus.


Studies of the microclimate of the external auditory canal in the dog. 3. Relative humidity within the external auditory meatus.


Studies of the effect of dietary lactobacilli on intestinal and urinary amines in pigs in relation to weaning and post-weaning dirrhoea.


A preliminary evaluation of a dithiosemicarbazone for the treatment of anaplasmosis.


Comparative efficacy of oxytetracycline and a dithiosemicarbazone in eliminating Anaplasma marginale infection in splenectomized calves.


The response of recently isolated strains of Eimeria meleagrimitis to chemotherapy.


Equine infectious anaemia: the role of Heinz bodies in the pathogenesis of anaemia.


The effect of cuff width on accuracy of indirect measurement of blood pressure in dogs.


Resistance of the fowl (Gallus domesticus) to invasion by its intestinal flora. I. The effect of hormonal bursectomy on the invasiveness of the intestinal microflora of the fowl.


A method for cannulating the gastrosplenic vein of sheep.


Investigations of the ability of strains of Trichostrongylus axei to produce immunity in calves and sheep.


The development and survival of free-living stages of Trichostrongylus colubriformis and Ostertagia circumcincta on pasture.


The efficacy of rafoxanide (3,5-diiodo-3'-chloro-4'-(p-chlorophenoxy) salicylanilide) against Haemonchus contortus in sheep.


A reovirus isolated from a pig.

A reovirus isolated from a pig.


Experimental pneumonia in the dog due to the virus of infectious canine hepatitis.


Hardwicke's Dabb-lizard (Uromastix hardwicki) as a reservoir of Salmonella in nature.


The influence of gelatin capsules upon the activity of bunamidine hydrochloride against Echinococcus granulosus in dogs.


Observations on a drug resistant strain of Eimeria tenella.


Polyacrylamide gel electrophoresis of lysates of mycoplasmas.


The composition of liver microsomes and levels of detoxicating enzymes in 9 animal species.


Infection of the tick Rhipicephalus appendiculatus with Theileria parva using an artificial feeding technique.


Equine infectious anaemia virus in strongyles.


Adherence of sensitized trypanosomes to peritoneal cells.


A ten-year survey of the cutaneous mycoses in the state of Rio Grande do Sul (Brasil). II. Candidiasis of skin and nail.


Ultrastructure of the physostomatous swimbladder of Rainbow trout (Salmo gairdneri).


Lung alveolar cell cytosomes: a consideration of their significance.


The distribution of cholinergic and adrenergic nerve fibres in the retractor penis and vas deferens of the dog.


Differentiation of epithelial cells in the mouse thymus.


Autoradographic study of RNA synthesis in isolated cells in culture from chick embryo spinal ganglia.


Disaggregation of S. typhimurium endotoxin with desoxycholate.


Experimental allergic thyroiditis in the guinea-pig. A light, fluorescence and electron microscopic study, with particular reference to the migration of lymphocytes through the vessel walls.


The effect of repeated injections of rabbit anti-guinea-pig thyroglobulin serum into guinea-pigs.


Perfusion fixation with glutaraldehyde for electronmicroscopy of human thyroid tumours.


Renal transplantation in rabbits. II. Morphological alterations in autografts.


Renal transplantation in rabbits. 3. Morphological alterations in allografts.


The effect of heat-labile serum factors on vitamin D-induced arteriosclerosis in mice.


Dopamine in a human islet cell carcinoma metastasis.


A possible discriminant test for hormone-responsive breast cancers. Estradiol--17 beta sensitive dehydrogenase activity.


The vitamin E-deficiency syndrome in pigs. II. Investigations on serum and tissue enzyme activity.


Heat stability of serum lactate dehydrogenase and its isoenzymes in young and adult cattle and sheep. Evaluation of a relative heat stability test and serum determination of alpha-hydroxybutyrate dehydrogenase in diagnostic work.


Serum enzyme activity of newborn calves, pigs and lambs.


Bovine enterovirus BEV-T64. Biological characteristics. Experimental genital and digestive tract infection.


Winter resistant oocysts in the pasture as a source of coccidial infection in lambs.


Studies on Erysipelothrix insidiosa S. rhusiopathiae. 1. Morphology, cultural features, biochemical reactions and virulence.


Studies on Erysipelothrix insidiosa S. rhusiopathiae. 2. Serological study.


An equation of consistency relating the harmonic mean relaxation time to sedimentation data.


Circular dichroism of crystalline L-cystine in potassium bromide disc. Possibility of exciton splitting.


Ferriporphyrins in aqueous alkaline medium: the effects of salt and "ageing".


Structural studies on the major and minor haemoglobin of the monkey Macaca irus.


Structure and function of hemocyanins. VII. The smallest subunit of alpha- and beta-hemocyanin of Helix pomatia: size, composition, N- and C-terminal amino acids.


The N-terminal region of soluble proteins from procaryotes and eucaryotes.


Cleavage of cytochrome c with cyanogen bromide.


Biochemical studies in the developing thoracic muscles of the tobacco horn worm. IV. Primary structure of cytochrome c.


Alpha-amylase inhibitors from wheat. Isolation and characterization.


Some properties of purified phytohemagglutinin from Lens culinaris seeds.


Role of bivalent cations in the phosphoglucomutase system. V. The phosphoglucomutase-copper(II) complex.


Protocollagen proline hydroxylase: molecular weight, subunits and isoelectric point.


Isolation and properties of a glycine-rich beta-glycoprotein of human serum.


Studies on the partial isolation of human renin.


Purification of a bacteriocin produced by Enterobacter cloacae DF 13.


Sex difference in the ferritin content of rat liver.


Isoelectric focusing of gamma crystallins. I. Characterization of rat lens components.


Polypeptide chain structure of sting ray immunoglobulin.


The character of homology between the N-terminal variable amino acid sequence of porcine and human immunoglobulin lambda chains.


Immunochemistry of sperm whale myoglobin. VI. Preparation and conformational analysis of eight mammalian myoglobins.


Immunochemistry of sperm whale myoglobin. VII. Correlation of immunochemical cross-reaction of eight myoglobins with structural similarity and its dependence on conformation.


Heme transfer from hemoglobin and ferrihemoglobin to some new ligands and its implication in the mechanism of oxidation of ferrohemoglobin by air.


Evidence for an irreversible reaction between nitrite and human methemoglobin.


Solvent perturbation and accessibility of the tryptophyl and tyrosyl residues in giant keyhole limpets hemocyanin.


The molecular size of three alpha-chain disease proteins.


Crystallization of thermostable glyceraldehyde-3-phosphate dehydrogenase after removal of coenzyme.


Comparative studies on the nature of the crosslinks in the collagen of various fish tissues.


Effects of hydroxyl compounds on the interaction of concanavalin A with polysaccharides.


Characteristics of mouse hemoglobin: a new type of hemoglobin in the Shanghai strain (Mus musculus bactrianus).


Pre-keratin isolated from epidermal microsomes.


Purification of human antihemophilic factor (factor VIII) by gel chromatography.


Alkali cation selectivity in a lipoprotein complex.


1,3-dioxane derivatives of muscarinic activity.


Effect of Bothrops Jararaca venom coagulant fraction on fibrinogen turnover.


Intermolecular forces and conformational changes in protein-ligand interactions.


Haemagglutination by bovine enteroviruses.


Nilverm (tetramisole) as an anthelmintic of outstanding efficiency.


Effect of insecticides on lactic acid concentration in the blood of buffalo-calves.


Studies on bovine semen diluted with illini variable temperature diluent. (Effect of storage temperature and addition of ascorbic acid).


Relative contribution of sire and dam in the determination of a character in mice (Mus musculus L.).


Effect of frequency of feeding on the growth of zebu (Hariana) calves, the digestibility of ration and nitrogen balance.


The effect of certain feed additives and supplements on growth patterns and haemoglobin concentration in young pigs.


Effect of lambing season on birth weight and weaning weight of Baunur sheep.


Studies on sheep nutrition. II. Plane of nutrition of grazing sheep during different months.


A report on the effect of feeding groundnut hay meal on the growth of chicks.


Effect of various levels of Chakunda leaf meal on growth and egg production of White Leghorn birds.


Notes on the efficacy of two mineral supplements (mixtures) on growth, feed efficiency, egg production, hatchability in White Leghorn pullets.


Studies  epidural anaesthesia in canine surgery.


Simplified artificial vagina for collection of rabbit semen for experimental use.


Suppression of cerebellar evoked responses in cerebral cortex during drowsiness in squirrel monkeys. (Saimiri maderae juruanus).


Cerebellar effects on the cerebrum. A microelectrical analysis of somatosensory cortex.


Quantitative studies in cobalt model epilepsy: the effect of cerebellar stimulation.


Cerebellar protracted post-effects. Study of the cat released from its movements.


The cerebello-thalamo-cortical pathway: ascending (specific and unspecific) and coricofungal controls.


Neurophysiological aspects of the cerebellar motor control system.


Some network characteristics of cerebello-cortical system. A study in the cat.


Ultrastructural studies in the developing cerebellum.


Study of auditory projections to cerebellum and some cerebello-hippocampo-neocortical circuits.


Effects of cooling the dentate nucleus on alternating bar-pressing performance in monkey.


Cerebellar symptoms as sequelae of traumatic lesions of upper brain stem and cerebellum.


Thoracic segmental input to the cerebellum.


The neurophysiology of the olivo-cerebellar system.


Ataxic dysarhria.

Ataxic dysarhria.


Editor's address.

Editor's address.


Serum cholesterol fractions, total esterified fatty acids, and lipoprotein electrophoresis in mentally retarded patients.


Characteristics of neural transmission from the semicircular canal to the vestibular nuclei of cats. 1. The characteristics of the dynamic response of specifically canal-dependent neural units in cat vestibular nuclei have been examined during sinusoidal rotation of the head in decerebrate cats over the narrow frequency range 0.-1.7 Hz.2. Unit action potential frequencies were averaged on line from extracellular steel micro-electrodes stereotaxically located in the vestibular nuclei through the intact cerebellum.3. Action potential frequency was approximately in phase with stimulus angular velocity, the mean phase for forty-six units being + 11. degrees S.E. of the mean +/- 2.2 degrees ). Correction for a form of dynamic asymmetry reduced this value almost to zero.4. The mean gain of thirty-nine single unit responses was 0.76 S.E. +/- 0.08) AP/sec per degrees /sec. The gain varied as the (-0.28) power of stimulus angular velocity, for the five cells appropriately tested.5. A method was evolved for computing the spontaneous condition of cells, in terms of an equivalent spontaneous firing frequency, f(sp) irrespective of whether they were spontaneously active or silent. This f(sp) value was normally distributed about a mean value of 11.2 AP/sec (range + 70 to - 40 AP/sec).6. Directionality was examined in 116 units, of which 62% were ipsilateral (e.g. cells on left side excited by left-going rotational velocity) and 38% contralateral. Ipsilateral units proved easier to isolate and retain than contralateral ones.7. No significant differences in mean phase or gain were found in the sub-sets of spontaneously active/inactive cells and ipsilateral/contralateral cells.8. It is inferred that the cell population examined was a functionally homogeneous one in which the neural signal was closely tied to the angular velocity of canal rotation for the narrow band of sinusoidal rotational stimuli here employed. It is suggested that this signal is probably retained essentially intact in the ensemble neural message fed forwards from this region.


Comparison of the reflex vasomotor responses to separate and combined stimulation of the carotid sinus and aortic arch baroreceptors by pulsatile and non-pulsatile pressures in the dog. 1. In the anaesthetized dog the carotid sinuses and aortic arch were isolated from the circulation and separately perfused with blood by a method which enabled the mean pressure, pulse pressure and pulse frequency to be varied independently in each vasosensory area. The systemic circulation was perfused at constant blood flow by means of a pump and the systemic venous blood was oxygenated by an extracorporeal isolated pump-perfused donor lung preparation.2. When the vasosensory areas were perfused at non-pulsatile pressures within the normal physiological range of mean pressures, the reflex reduction in systemic vascular resistance produced by a given rise in mean carotid sinus pressure was significantly greater than that resulting from the same rise of aortic arch pressure.3. On the other hand, when the vasosensory areas were perfused at normal pulsatile pressures and within the normal physiological range of mean pressures, there was no difference in the size of the reflex vascular responses elicited by the same rise in mean pressure in the carotid sinuses and in the aortic arch.4. Whereas the vasomotor responses elicited reflexly by changes in mean carotid sinus pressure are modified by alterations in pulse pressure, those evoked by the aortic arch baroreceptors through changes of mean pressure are only weakly affected by modifications in pulse pressure. Evidence for this was obtained from single stepwise changes of mean pressure in each vasosensory area during pulsatile and non-pulsatile perfusion, and from curves relating the mean pressure in the carotid sinuses or aortic arch and systemic arterial perfusion pressure.5. The vasomotor response elicited by combined stimulation of the carotid sinus and aortic arch baroreceptors was greater than either response resulting from their separate stimulation.6. When the mean perfusion pressures in the two vasosensory areas are changed together, the curve relating mean pressure to systemic arterial pressure during pulsatile perfusion of the areas is considerably flatter than that for non-pulsatile perfusion.7. Increasing the pulse pressure in the carotid sinuses or aortic arch caused a decrease in systemic vascular resistance, the response elicited from the carotid sinuses being the larger.8. Altering the phase angle between the pulse pressure waves in the carotid sinuses and aortic arch had no effect on systemic vascular resistance.9. In both vasosensory areas, increasing the pulse frequency caused a reduction in systemic vascular resistance.


The cite of action of nerves in the pulmonary vascular bed in the dog. 1. The effects of stimulation of the thoracic vagosympathetic nerve or upper thoracic sympathetic chain on the pulmonary vascular resistance have been studied in atropinized, isolated, ventilated lung lobes under various conditions of pulmonary circulation perfusion. Throughout the nerve-stimulation tests bronchial circulation perfusion was maintained or temporarily interrupted.2. The pulmonary vascular resistance increase evoked by nerve stimulation (a) occurred in the absence of tidal air changes; (b) did not consistently differ during predominantly ;sluice' and ;non-sluice' conditions of pulmonary circulation perfusion; (c) was approximately one and a half times greater during constant pressure than during constant volume inflow perfusion of the pulmonary circulation; and (d) was greater during reverse than during forward perfusion.3. In lung lobes perfused in either direction at constant volume inflow nerve stimulation produced an increase in inflow pressure and a diminution in total lung blood volume reflected by a temporary increase in blood outflow.4. In lung lobes in which neither the pulmonary nor the bronchial circulations were perfused and the capillaries were completely blocked by high intratracheal pressures, thus isolating the pulmonary arterial system from the venous system, nerve stimulation produced a diminution in the blood volume of both systems.5. Nerve stimulation produced a rise in bronchial arterial pressure in the absence of pulmonary circulation perfusion.6. Further evidence is adduced that pulmonary vasomotor nerve responses do not depend upon the transfer of transmitter substances from the bronchial to the pulmonary circulation.7. The possible significance of these observations in relation to the site of action of pulmonary vasomotor nerves is discussed.


Field potentials evoked in the brain stem of the cat by stimulation of the carotid sinus, glossopharyngeal, aortic and superior laryngeal nerves. 1. In a primarily topographical study, the field potentials evoked in the brain stem of the cat by stimulation of the sinus, glossopharyngeal (IX), aortic and superior laryngeal (SLN) nerves have been recorded with glass micro-electrodes.2. Extracellular negative potentials were evoked in the region of the nucleus of the tractus solitarius and in the lateral reticular formation (LRF) by electrical stimulation of all four nerves. There were differences in the form of these potentials amongst the nerves, particularly between sinus-IX and aortic-SLN. The potentials were identified as post-synaptic with early and late components and were sometimes preceded by an afferent volley.3. Extracellular positive potentials were evoked in the subnucleus reticularis medialis medullae oblongatae and the nucleus reticularis gigantocellularis. Intracellularly recorded hyperpolarizations recorded from six cells had the same time course as the extracellular positivity. Spontaneously active cells encountered in these regions were sometimes depressed for the duration of the positivity.4. Each of the above field potentials was maximal in the region of Horsley-Clarke A. P. co-ordinates -10 to -13 mm.5. At A.P. co-ordinates of -15 to -17 mm negativity showing post-tetanic potentiation was evoked, at latencies similar to the negativity in the LRF, in the commissural nucleus of Cajal, the dorsolateral reticular formation and the medial reticulo-spinal tract.6. Negative potentials were evoked in the contralateral LRF.


An analysis of the inhibition of phrenic motoneurones which occurs on stimulation of some cranial nerve afferents. 1. Inhibition and excitation of spontaneous phrenic nerve discharges in response to stimulation of the sinus, glossopharyngeal, aortic and superior laryngeal (SLN) nerves has been investigated in cats.2. The inhibition, in response to a single shock, had a latency of 5-10 msec and lasted for 20-40 msec; the response to SLN stimulation was the most prolonged.3. Excitation of phrenic motoneurones also occurred and was seen either before or after the end of the inhibition of the inspiratory burst and sometimes also during expiration.4. Intravenous strychnine blocked the inhibition.5. Intracellular recording from phrenic motoneurones showed that hyperpolarization was evoked by each nerve during the central phrenic depolarizing potential (CPDP) but only rarely in the interval between these potentials.6. When the CPDP was suppressed, hyperpolarization could sometimes be evoked.7. There were no changes in amplitude or time course of hyperpolarization during the passage of current through the cell membrane. No change in membrane conductance could be shown by passing current pulses.8. Raising the pressure in the carotid sinus also depressed phrenic activity and evoked a hyperpolarization whilst the CPDP was suppressed.9. Inspiratory interneurones in the brain stem were suppressed by nerve stimulation and by a rise in carotid sinus pressure.10. Expiratory interneurones in the brain stem were both excited and suppressed by electrical stimuli and unaffected by a change in carotid sinus pressure.


Responses of cells in the brain stem of the cat to stimulation of the sinus, glossopharyngeal, aortic and superior laryngeal nerves. 1. The distribution and properties of 146 brain stem units whose activity was influenced by electrical stimulation of sinus, glossopharyngeal, aortic and superior laryngeal nerves were studied in cats.2. Cells excited by electrical stimulation of one or more of the nerves were distributed throughout the brain stem in an area extending rostrocaudally from Horsley-Clarke co-ordinates P 7.5 to P 16.5 and laterally between 1.5 and 5 mm from the mid line.3. Most of the units excited (n = 129) or inhibited (n = 17) by nerve stimulation were localized in the nucleus reticularis gigantocellularis and nucleus reticularis parvocellularis.4. The latencies of activation varied from as short as 1.5 msec to as long as 35-40 msec. A high degree of convergence was observed.5. Evoked responses varied from single spikes to bursts of impulses, the frequencies of which were sometimes as high as 1000/sec following a single shock to the nerve.6. Spontaneously active cells inhibited (seventeen) by nerve stimulation were located primarily in NRG and NRP. None of the cells was inhibited by stimulation of one nerve and excited by stimulation of the others.7. The responses of cells to a sudden rise in carotid sinus pressure were similar in kind to the responses to electrical stimulation of the nerves.


The role of the cervical sympathetic nerve in the regulation of oxygen consumption of the carotid body of the cat. 1. Carotid body blood flow (c.b.f.) and carotid arterial-carotid body venous oxygen (A-V O(2)) difference were measured and carotid body oxygen consumption calculated in twenty-six cats anaesthetized with pentobarbitone sodium, paralysed with gallamine triethiodide and ventilated mechanically.2. With the sinus nerves intact and with blood gas tensions and carotid sinus pressure within physiological limits, section of either the pre- or post-ganglionic cervical sympathetic nerve on the same side caused an average rise in c.b.f. of 9.2 mul./min, in A-V O(2) difference of 0.09 ml./100 ml. and in carotid body oxygen consumption of 0.075 mul./min.3. When the pre- or post-ganglionic cervical sympathetic nerves were stimulated, c.b.f. and A-V O(2) difference fell. The fall in c.b.f. was enhanced at high P(a, CO2); the fall in A-V O(2) difference and in calculated oxygen consumption was enhanced at low mean arterial pressure (M.A.P.) or P(a, O2).4. Following sympathectomy, a reduction of M.A.P. at constant P(a, O2) and P(a, CO2) caused a fall in c.b.f. and a commensurate rise in A-V O(2) difference so that carotid body oxygen consumption remained approximately constant.5. When P(a, O2) was altered over the range 35 to > 400 mm Hg, or P(a, CO2) over the range 27-70 mm Hg at constant M.A.P., c.b.f. changed by amounts which were similar to those observed when the sympathetic nerves were intact and A-V O(2) difference changed in the opposite direction so that carotid body oxygen consumption similarly remained constant.6. Comparison of these results with those observed when the sympathetic nerves were intact indicates that the sympathetic nerves exert a vasoconstrictor effect upon carotid body blood vessels over a wide range of blood gas tensions and arterial pressure and that they also tend to diminish the rate of carotid body oxygen consumption. The mechanisms which may be involved in this regulation are discussed.


The effect of hypoxia, hypercapnia and hypotension upon carotid body blood flow and oxygen consumption in the cat. 1. Carotid body blood flow (c.b.f.), the arterio-venous oxygen (A-V O(2)) difference and oxygen consumption were measured in forty-seven cats, anaesthetized with pentobarbitone, paralysed with gallamine and ventilated artificially. Carotid sinus and cervical sympathetic nerves were intact throughout.2. A system for perfusing the carotid body artificially with blood is described and evidence is given which shows that similar results were obtained whether the carotid body was naturally or artificially perfused.3. With arterial pressure, blood gas tensions and pH within physiological limits, c.b.f. varied between 33 and 68 mul./min, average 41.5; A-V O(2) difference between 0.21 and 0.46 ml./100 ml., average 0.34, and calculated oxygen consumption between 0.115 and 0.195 mul. O(2)/min, average 0.147.4. With constant mean arterial pressure, hypoxia (30-40 mm Hg P(a, O2)) or hypercapnia (> 50 mm Hg P(a, CO2)) resulted in a small increase of c.b.f., up to 14 mul./min above control; an average fall of A-V O(2) difference by 49% of control and an average fall of oxygen consumption by 36% of control.5. Carotid body blood flow fell linearly with mean arterial pressure over the range 100-170 mm Hg, the slope of the curve varying between 0.78 and 1.22 mul. min(-1). mm Hg(-1). M.A.P. A-V O(2) difference was unaffected so that oxygen consumption fell in proportion to c.b.f.6. It is concluded that the unique response of the carotid body to these stimuli is a fall in oxygen consumption and that this bears a closer relation to the known pattern of chemoreceptor discharge than do changes in total blood flow.


Interaction of cortical evoked potentials in the rat. 1. Unitary and mass potentials were recorded with glass micropipettes at different depths in and around the primary somatosensory area of the cortex in rats anaesthetized with urethane; in addition, surface mass potentials were recorded with chlorided silver ball electrodes. Potentials were evoked by stimuli to the contralateral forepaw and the contralateral cortex. Observations were confined to potentials evoked within 20 msec of stimulation.2. If forepaw stimuli were applied at times when the cortex was not showing spontaneous activity, one component of the evoked response was a widespread depth negativity. This was accompanied by a smaller surface positivity which had the same time course. It could be recorded over the same area of cortex. Unitary activity was found with the same latent period and spatial distribution as the depth negativity. These components of the evoked mass and unitary responses to forepaw stimulation were absent if times of spontaneous cortical activity were chosen for delivering the stimuli.3. Contralateral cortical stimuli evoked mass activity similar to the component of the mass response to forepaw stimulation described in 2. Stimuli given simultaneously to the two sites elicited less unitary activity than the sum of the unitary activity evoked by the two stimuli separately. The mass activity exhibited the interactions which would be expected on the hypothesis that it is generated by the unitary activity. The time course of the interaction is described.4. The interaction was confined to the components of the evoked potentials which were only present if stimuli were applied when the cortex was quiescent. Stimuli applied when the cortex was active evoked mass and unitary potentials which showed no interaction.


Effects of intragastric hyperosmolal solutions on gastric function. 1. The effects of intragastric hyperosmolal solutions on resting and secreting stomachs of anaesthetized cats have been studied.2. Hyperosmolal solutions reduced acid secretion in response to histamine and gastrin. There was a significant correlation between increase in osmolality and decrease in acid response to small doses of gastrin. A continuous acid secretion produced by large doses of gastrin was not significantly reduced.3. The loss of H(+) from resting stomachs is related to the pH and osmolality of the instilled fluid. The loss was greatest at low pH and high osmolality, but was insufficient to account for the H(+) loss from secreting stomachs at similar pH and osmolality.4. The Na(+) output into resting stomachs was increased by hyperosmolal solutions, the increase being related only to the osmolality of the solutions. For the same degree of hyperosmolality there was no difference between the sodium output into resting and secreting stomachs.5. The H(+) deficit associated with intragastric hyperosmolal conditions does not seem to depend upon a neural mechanism, a blood-borne hormone, or a reduction in gastric blood flow. Evidence is presented that diffusion, exchange or neutralizing mechanisms are unlikely to be responsible for the H(+) deficit. It is suggested that inhibition of oxyntic cell activity by release of a chemical agent from the surface cells of the mucosa is the most likely explanation of the results observed.6. The possible physiological significance of intragastric hyperosmolal inhibition of acid secretion is discussed.


Place and modality analysis in caudal reticular formation. 1. Evoked potentials and unit responses were studied under chloralose anaesthesia in a restricted region of the caudal bulbar reticular formation of the cat which is known anatomically to receive a preferential spinal input.2. Responses were analysed in terms of place and sensory modality and show varying degrees of place and modality convergence, as well as preferential responses for certain loci of stimulation.3. Evidence is presented which suggests that some unit responses are generated in dendrites.4. The response properties of the whole population are compared with those obtained from other reticular regions in previous identical experimental series. It is shown that the integrated activity of the ascending reticular formation acting as a whole would enable the organism to discriminate, to a greater or lesser degree, place and modality from the convergent peripheral input to the reticular formation.


Observations on the change in shape of blood platelets brought about by adenosine diphosphate. 1. An optical method used for measuring platelet aggregation was adapted for measurements of the change in shape of platelets that rapidly follows the addition of the aggregating agent adenosine diphosphate (ADP).2. Measurements were made using dilute suspension of platelets with sufficient EDTA to prevent their aggregation.3. Measurements of the velocity and magnitude of the optical effects of the shape change were highly reproducible.4. Volumetric measurements showed that the shape change is not associated with an increase in mean platelet volume.5. The velocity of the shape change had a temperature coefficient of about 4.5.6. The velocity and magnitude of the shape change were not affected by pH between 5.8 and 9.2.7. The dependence of the velocity of the shape change on the ADP concentration was in accordance with Michaelis-Menton kinetics. The K(m) was about 7.2 x 10(-7)M.8. The velocity of the shape change was inhibited competitively by ATP, adenosine and 2-chloroadenosine but not by AMP. When the inhibitors were added after the maximum of the shape change they caused a concentration-dependent diminution in the record of the change.9. The results suggest that the shape change is initiated by reaction of the agonist ADP with specific receptor sites on the platelet membrane which leads to energy-requiring changes in the structures responsible for maintaining the disk shape of normal platelets.


Plaque assay in petri dishes in the absence of CO2 atmosphere.


Essays on immunization of mice with ultraviolet radiated virulent and avirulent culture forms of Trypanosoma cruzi.


Indirect haemagglutination test for Chagas' disease, with a simple method for survey work.


Theoretical considerations of the role of psychological factors in pathogenesis and etiology of essential hypertension.


The blood pressure control system: a critical and methodological introduction.


Haemodynamics and emotional stress.

Haemodynamics and emotional stress.


Some psychological aspects of the experimental investigation of hypertension.


Emotional stress and sympatho-adrenomedullary and related physiological reactions with particular reference to cardiovascular pathology.


Psychosomatic research in essential hypertension: retrospect and prospect.


Patterns of hypertension.

Patterns of hypertension.


Metabolic compartmentation at the molecular level: the function of a multienzyme aggregate in the pyrimidine pathway of yeast.


Some characteristics of the mitochondrial and soluble forms of malate dehydrogenase in lemon fruits.


Characterization of the highly active isocitrate (NADP+) dehydrogenase of Azotobacter vinelandii.


Properties of muscle glyceraldehyde-3-phosphate dehydrogenase from the cold-adapted antarctic fish Dissostichus mawsoni.


Electron paramagnetic resonance studies of 95Mo-enriched NADH dehydrogenase isolated from iron-deficient Azotobacter vinelandii.


Disulfide reduction in rat liver. II. Chromatographic separation of nucleotide-dependent disulfide reductase and GSH-disulfide transhydrogenase activities of the high-speed supernatant fraction.


Comparative properties of 2,3-oxidosqualene-lanosterol cyclase from yeast and liver.


Kinetics of purified catechol O-methyltransferase.


Control of pyrimidine biosynthesis in mammalian tissues. 3. Multiple forms of aspartate transcarbamoylase of mouse spleen.


ATP-sulphurylase in spinach leaves.

ATP-sulphurylase in spinach leaves.


Sulfhydryl inhibitors and enzyme-substrate interactions of carbamyl phosphate synthetase.


Isolation and partial characterization of an elastase-associated acidic endopeptidase and its interaction with elastase at low ionic strength.


Isolation and characterization of a UDPase from cerebellum.


Porphyrin biosynthesis in soybean callus. V. The porphobilinogen deaminase-uroporphyrinogen cosynthetase system. Kinetic studies.


Aconitate hydratase. Some new observations with especial relation to its use as a test system for fluorocitrate, together with studies on the electrophoretic separation of components of the crude enzyme.


Measurement of aminolaevulinate synthetase activity in normal mouse liver with [2-14C] glycine.


Immunochemical studies on the interrelationships between sulfite reductase and other NADPH-linked reductase activities of Escherichia coli and Salmonella typhimurium.


Phosphotransacetylase of Lactobacillus fermenti, properties of the enzyme and determination of coenzyme A.


Lecithin: cholesterol acyl transferase activity in human cerebrospinal fluid.


Some properties of abnormal red blood cell pyruvate kinase.


Acetylcholinesterase: new evidence for an acetyl-enzyme intermediate.


Lysosomal beta-galactosidases of rat kidney.


Role of histidine in the active site of alkaline protease from Aspergillus flavus derived from kinetic data.


Uridine diphosphoglucose 4-epimerase: kinetic isotope effect.


On some methods of drawing inferences about antigen systems from serological data.


A class of permutational and multinomial tests arising in epidemiological research.


Statistical models for animal survival time in mouse lymphoma.


The simulated population method of analysis of animal painting experiments in cancer research.


The equivalence of different sets of stability conditions for multiple allelic systems.


Electron-microscope studies on Fasciola hepatica. VIII. The development of the vitelline cells.


Plasmodium falciparum: nucleic acid and pigment changes in resistant strains produced by antimalarial drugs.


Oesophagostomum radiatum: adult nematodes and intestinal hemorrhage.


Strongyloides myopotomi: fine structure of the body wall and alimentary tract of the adult and third-stage larva.


Histomonas meleagridis: effect of gamma radiation on in vitro growth.


Leishmania tropica: chemostatic cultivation.


Hymenolepis nana: mouse subcutaneous tissue responses to larval stages.


Carbohydrate metabolism in Babesia rodhaini: investigations with 14C-labeled substrates and enzyme assays.


Trypanocidal properties of 5'-O-Sulfamoyladenosine, a close structural analog of nucleocidin.


Plasmodium cynomolgi: x-irradiation and development of exo-erythrocytic schizonts in Macaca mulatta.


Trichinella spiralis: diagnostic value of creatine kinase levels in rat and man.


Organic matrix of cestode calcareous corpuscles.


Vibrissae structure in the rhesus monkey.


Peri-menstrual sexual behavior among rhesus monkeys.


Luteinizing hormone levels in nonhuman primates.


Ultrastructure of hepatocytes during mitosis.


Leiomyosarcomas induced by oral administration of N-methyl-N'-nitro-N-nitrosoguanidine in gastric cysts grafted in subcutaneous tissue of mice.


Effect of carbazilquinone on transplantable and primary tumors in mice.


Relationship between antitumor activity and chemical structure in psychotropic agents.


Promotion by DNA of the photoinduced radical production from 4-nitroquinoline 1-oxide in aqueous medium at 77 degrees K and its mechanism.


Sex difference in alteration of steroid delta4-hydrogenase activity in liver microsomes from rats bearing Walker carcinosarcoma-256.


In vitro malignant transformation of cells derived from rat liver by means of aflatoxin B1.


Establishment and some characteristics of new transplantable ascites tumors produced by rat liver cells transformed in culture with 4-nitroquinoline 1-oxide.


Proliferation kinetics of sarcoma-180.

Proliferation kinetics of sarcoma-180.


Metabolism of carcinogenic 4-hydroxyaminoquinoline 1-oxide in mice.


Induction and regression of Friend leukemia in vaccinated mice by means of parabiosis.


Electron microscopic study of the choroid plexus in Talpa europaea (L.).


Cytocidal action of carcinogenic 4-nitroquinoline 1-oxide and related compounds.


Photometric studies on the myeloarchitecture of the human parietal lobe. II. Postcentral region.


Comparative histochemical study of the corpus striatum.


The afferent components of the hypoglossal nerve. An experimental study with toluidine blue and sliver impregnation methods.


Peyote constituents: chemistry, biogenesis, and biological effects.


Synthesis and biological activity of deuteriobenzyl-d7-penicillin.


Synthesis of azabiotin analogs as potential cofactors for biotin-dependent enzymes.


Acetaminophen prodrugs. 3. Hydrolysis of carbonate and carboxylic acid esters in aqueous buffers.


Biopharmaceutical studies on guaiacol glycerol ether and related compounds. IV. Drug in blood and bile.


Chlorpromazine metabolism. I. Quantitative fluorometric method for 11 chlorpromazine metabolites.


Effect of pH on monolayers of cellulose acetate phthalate.


Benzyloxyamines as possible inhibitors of histamine biosynthesis.


Drug permeation through thin model membranes. I. Development of a polymeric model biomembrane.


New method for assaying antiapomorphine activity in pigeons.


Chemical balance as a rheometer for biological fluids.


Kinetics of the decomposition of a Mannich base.


Effect of vehicles on metabolism of serotonin and imipramine.


Characterization of tablet surfaces by their critical surface-tension values.


Rotating-flask method for dissolution-rate determinations of aspirin from various dosage forms.


Extraction of morphine enhanced by addition of N-methyl-3-piperidyl-(N'N')-diphenylcarbamate.


Theoretical approach to sustained-release multiple-dose therapy: noncumulative attainment of desired blood level.


Metabolism of flurazepam, a benzodiazepine, in man and dog.


Interaction of nitrogen dioxide with cholesterol monomolecular films: effect of initial surface pressure, time of exposure, and concentration of nitrogen dioxide.


Crystal pseudopolymorphism of cephaloglycin and cephalexin.


Potentiometric titration of allantoin in cream formulations.


Influence of several autonomic drugs on sodium nitroprusside and oxotremorine-induced hypothermia in immature and mature mice.


NMR analysis of mestranol bulk drug.

NMR analysis of mestranol bulk drug.


Fluorometric determination of reserpine and related compounds by reaction with vanadium pentoxide.


Automated dual extraction procedure for analysis of phenmetrazine hydrochloride tablets.


Quantitative analysis and stability of 5(or 4)-[3,3-bis(2-chloroethyl)-1-triazeno]imidazole-4(or 5)-carboxamide in acidic aqueous solutions.


Complexes of ergot alkaloids and derivatives. V. Interaction of methysergide maleate and caffeine in aqueous solution.


Substituted benzamides with potential CNS-depressant and hypotensive activity.


Cactus alkaloids. 8. Isolation of N-methyl-3,4-dimethoxy-beta-phenethylamine from Ariocarpus fissuratus var. fissuratus.


Effects of mefruside on renal hemodynamics.


1-(3,4-dimethoxyphenyl)-2-propanol effect on conditioned avoidance response in the rat.


Evidence for capacity-limited biotransformation of sulfanilamide.


Apparent dose-dependent elimination kinetics as an experimental artifact.


Preparation of ethyl diphenamate in ethanol using potassium diphenimide and 2-chloroethanol.


Flocculation theory and polysorbate 80-sulfaguanidine suspensions.


Carboxyl protection using salt formation for the synthesis of linear sequential polypeptides: synthesis of poly-(L-tyrosyl-L-glutamyl-L-alanylglycyl)glycine-1-14C ethyl ester.


The permanence of tissue binding of thyroxine in the rat. 1. Male rats were given radiothyroxine and after 24 hr, approximately half the blood volume was replaced by exchange transfusion.2. Plasma concentration of radiothyroxine 2 hr after exchange averaged 81.1% of the value before exchange. This compared with a predicted mean of 97.1% assuming a free and rapid exchange of thyroxine throughout the thyroxine distribution space. The difference between the observed and expected value was highly significant.3. The effective exchangeable pool of thyroxine was found to be approximately twice the plasma volume.4. From these and other observations it is suggested that the liver and plasma constitute most of the exchangeable pool of thyroxine.5. This experiment supports a model of thyroxine metabolism which envisages essentially permanent binding of thyroxine by tissues other than the liver.


Paradoxical temperature dependence of sodium and potassium fluxes in human red cells. 1. The effect of temperature on passive movements of sodium and potassium through the red cell membrane has been determined in the presence of various monovalent anions.2. Passive sodium and potassium fluxes varied in a complex way with temperature, when the isotonic electrolyte media contained 120 mM thiocyanate or salicylate. Between 0 and 18 degrees C the fluxes decreased with increasing temperature. Above 18 degrees C the rate of permeation increased when temperature was increased.3. The ability of anions to induce an increased sodium influx at 0 degrees C was gradually intensified through the following sequence of anions:HCO(3) (-) < Cl(-) = Br(-) < NO(3) (-) < I(-) << SCN(-) << salicylate.4. It is proposed that the anion induced effects on the cation permeability are secondary to binding of anions to fixed cations in the red cell membrane. The temperature dependence of the cation fluxes is assumed to reflect the binding on anions to fixed charges at temperatures between 0 and 18 degrees C.


Effect of some monovalent anions on chloride and sulphate permeability of human red cells. 1. The permeability of human red cells to (36)Cl(-) and to [(35)S]SO(4) (2-) was studied in the presence of various monovalent anions.2. A maximum decrease of anion permeability was found in a study of the steady-state exchange of (36)Cl in a medium containing 120 mM salicylate. The exchange had a half-time of 3 hr at 0 degrees C, a reduction of normal chloride permeability by a factor of 10(5). The activation energy of chloride exchange decreased from a value of 45 to 22 kcal/mole in the interval between 0 and 10 degrees C. Simultaneous determination of the permeability to potassium and chloride proved that salicylate induced a reversal of the normal selectivity of red cells at 0 degrees C (permeability coefficient P(K) of 3.5 x 10(-9) cm/sec to be compared with a P(Cl) of 2 x 10(-9) cm/sec).3. In contradistinction to the slow movement of (36)Cl, the exchange of [(14)C]salicylate was completed within 4 min, when red cells were suspended at 0 degrees C in the salicylate medium.4. A study of the sulphate permeability at 38 degrees C showed that the rate of steady-state exchange decreased, when chloride was replaced by lyotropic anions other than bromide. The sequence of the permeability decrease was: Cl(-) = Br(-) < I(-) < NO(3) < SCN(-) < salicylate, the same sequence which previously has been shown to increase the permeability to sodium and potassium. The activation energies of sulphate exchange were 32 kcal/mole (chloride medium), and 38 kcal/mole (thiocyanate medium).5. Sufficient data were obtained during the study to demonstrate that when equilibrium has been obtained, there is a good agreement between the values of (36)Cl (cell water)/(36)Cl (extracellular water) and of {[(35)S]SO(4) (cell water)/[(35)S]SO(4) (extracellular water)}((1/2)).6. It is concluded that the anion-induced changes of permeability are due to binding of anions to fixed cationic charges in the red cell membrane.


Invariant features of spatial summation with changing locus in the visual field. 1. Spatial summation curves have been determined under photopic conditions for loci between 5 and 55 degrees from fixation. At each locus the area and Weber fraction for the largest stimulus showing complete summation (Sc) has been estimated. While the area of Sc increases progressively towards the periphery, its Weber fraction remains constant.2. The invariance of the Weber fraction for Sc, coupled with changes in its area, have been compared with similar findings observed during changes in adaptation level, in impaired fields, and during accommodative and convergence changes. It is suggested that the Weber fraction for Sc may be an important parameter of visual function which is maintained under changing conditions by alterations in the area over which background energy is summated.3. It has been shown that, for stimulus areas up to at least 1 log unit greater than Sc, all the summation curves from 5 to 55 degrees from fixation can be superimposed by simple displacement along the log area axis. For loci closer together, the superimposition has been shown for larger ranges of areas beyond Sc. This suggests that, so far as spatial summation is concerned, changes in locus serve only to change the spatial scale of the visual system.4. Comparisons have been made between the area of Sc at various loci and the sizes of the central regions of the receptive fields of retinal ganglion cells determined electrophysiologically in the primate.


Physiological and morphological identification of horizontal, bipolar and amacrine cells in goldfish retina. 1. Intracellular recordings were made from various types of cells in the isolated goldfish retina, and Procion Yellow was injected from the recording pipette in order to identify histologically the structure recorded. The dye diffused and stained the cell body and processes down to the fine branches.2. S-potentials were identified as coming from the external horizontal cells and from the internal horizontal cells. Both L- and C-type S-potentials were found in both regions, and no histological differences were seen in cells giving these two types of responses. S-potentials recorded from the external horizontal cells showed less spatial summation than those recorded from the internal horizontal cells.3. Bipolar cell responses consisted of sustained potentials associated with an antagonistic centre-surround type receptive field (on-centre, off-surround or vice versa). Spike activity was not observed in bipolar cells.4. Amacrine cells responded with transient depolarization both at the beginning and at the end of illumination. They sometimes showed spike activity. The amplitude of on- and off-depolarization showed slight dependence on stimulus geometry but a distinct centre-surround organization was not observed.


Electrophysiological evidence for the existence of orientation and size detectors in the human visual system. 1. The evoked potential in response to a grating alternating in phase at 8 c/s was recorded as a function of contrast from the occiput of man.2. It was found that a linear relation exists between the log. of contrast and the amplitude of the evoked potential.3. Extrapolation to zero amplitude voltage of the regression line between the amplitude of the evoked potential and log. contrast predicts the psychophysical threshold. This law was found to hold over the wide range of spatial frequencies tested.4. Below 3 c/deg the results are best fitted with two regression lines; one of these is generated from the foveal and the other from the parafoveal representation in the cortex.5. The slope of the regression lines was found to be almost independent of either the spatial frequency or the area of the stimulus grating.6. The slope of the regression lines could be markedly increased by using as a stimulus either two different spatial frequencies, or two different orientations, presented simultaneously.7. Using the evoked potential the selectivity to orientation was found to be so high that a channel was not influenced by another orientation 15 degrees away.8. The channels selectively sensitive to spatial frequency were highly selective and were not influenced by another spatial frequency one octave removed in spatial frequency.9. It is concluded that in man there exist neurones highly selective to both orientation and spatial frequency.


The range of thermal insulaton in the tissues of the new-born baby. 1. Rectal temperature and skin temperatures were measured in twenty-eight naked babies weighing 1.1-4.5 kg, lying supine in environments of 25-31 degrees C when air speed was 4-7 cm/sec. The ratio of external insulation to internal or tissue insulation for the whole body averaged 2.7 but varied inversely with body weight; the ratio was higher than this on the trunk, and five times lower than this on the hand and foot. The mean ratio rose threefold when environmental temperature was increased to 34-35 degrees C.2. Direct measurements of heat flow from the back of a hand placed in a water jacket maintained at 32 degrees C were made in thirty-three babies. Heat loss averaged 3 kcal/m(2).hr. degrees C at low environmental temperature, but the loss was often rather less than this in the first 24 hr of life. Heat loss from the hand increased three- to fourfold, during exposure to an environment of 35 degrees C.3. When babies more than 48 hr old were exposed to an environment of 34-35 degrees C, heat loss from the hand only increased when rectal temperature reached between 36.6 and 37.3 degrees C; a slightly higher rectal temperature was usually reached before heat loss rose in babies less than 24 hr old.4. Similar methods were used to study specific tissue insulation in three babies with congenital defects of the brain who lacked evidence of temperature control. No changes in insulation were detected in these three babies following changes in environmental temperature.5. It is concluded that the range and pattern of control that can be exerted over the specific thermal insulation of the tissues is essentially the same in babies 2-20 days old as it is in adult life.


A comparison of peripheral and rubrospinal synaptic input to slow and fast twitch motor units of triceps surae. 1. Post-synaptic potentials (PSPs) evoked by electrical stimulation of a variety of input systems have been compared in triceps surae motoneurones innervating slow and fast muscle units, the speed of contraction of which was also determined.2. Stimulation of high threshold afferents in both flexor and extensor muscle nerves, and of joint afferents, evoked polysynaptic PSPs which were predominantly hyperpolarizing in both fast and slow twitch motor units.3. Volleys in cutaneous afferents in the sural and saphenous nerves evoked polysynaptic PSPs composed of mixtures of inhibitory and excitatory components. The inhibitory components were predominant in slow twitch motor units, while in fast twitch units there was a trend towards excitatory predominance.4. Repetitive stimulation of the red nucleus caused predominantly inhibitory PSPs in slow twitch units and mixed or predominantly excitatory PSPs in fast twitch units. There was a correlation in the excitatory/inhibitory balance between PSPs of cutaneous and rubrospinal origin in those motoneurones in which both types of PSPs were studied.5. The amplitudes of group Ia disynaptic inhibitory PSPs were found to be correlated with motor unit twitch type: IPSPs in slow twitch units were larger than those in fast twitch units. Rubrospinal conditioning volleys were found to facilitate group Ia IPSPs in both fast and slow twitch motor units.6. The results suggest that there may be several basic patterns of synaptic input organization to motoneurones within a given motor unit pool. In addition to quantitative variation in synaptic distribution, there is evidence that qualitative differences in excitatory to inhibitory balance also exist in the pathways conveying input from cutaneous afferents and rubrospinal systems to triceps surae motoneurones. These qualitative differences are correlated with the motor unit twitch type.


Secretory behaviour and histamine formation in the rat Heidenhain pouch following antrectomy. 1. In conscious rats provided with a Heidenhain pouch, the changes in the secretion of acid and pepsin following antrectomy were investigated in the interdigestive state and in response to graded doses of intravenous hog gastrin II and methacholine. The change in mucosal histamine formation (histamine-forming capacity, HFC, i.e. histidine decarboxylase activity) was determined in the fasting state in the Heidenhain pouch following antrectomy.2. Antrectomy was followed by a substantial reduction in the interdigestive secretion of acid.3. Methacholine infusion when the antrum was intact evoked a maximal acid secretory response that exceeded twice the response obtained with gastrin.4. After resection of the antrum the acid response to graded doses of methacholine and to gastrin at maximal but not at submaximal dose levels was significantly reduced.5. After antrectomy, threshold or submaximal infusion of gastrin accentuated the acid secretory responses to methacholine, but did not restore the maximal secretory response to methacholine obtained before antrectomy.6. The changes in pepsin secretion following antrectomy were similar to those in acid secretion but smaller.7. Mucosal HFC of the pouch was significantly lowered following antrectomy.8. After antrectomy gastrin failed to accelerate histamine formation in the mucosa in the usual way.


Early facilitation at corticomotoneuronal synapses. 1. Corticomotoneuronal EPSPs have been generated in lumbar motoneurones of the monkey by single and paired corticospinal volleys. The facilitation of the second of a pair of EPSPs with respect to the size of the first has been measured.2. The relationship between the degree of facilitation of the second response and the interval between the two volleys has been studied. Average facilitation of minimal EPSPs was found to be maximal about 2 msec after the arrival of the corticospinal volley and to decay roughly exponentially thereafter with a time constant of about 10 msec.3. The degree of facilitation varied from one minimal corticomotoneuronal EPSP to another but this facilitation was not statistically correlated with the time course of the individual EPSPs.4. Significant facilitation (0.4) was still present 10 msec after a corticospinal volley so that this phenomenon could play a part in the initiation of motoneuronal discharge by corticospinal activity at natural frequencies of the order of 100 impulses/sec.


Length changes within isolated frog muscle spindle during and after stretching. 1. The length changes within the frog muscle spindle during stretch have been studied by stroboscopic photomicroscopy. Attention was focused on the length changes within the central reticular zone and these changes were related to the features of the receptor potential.2. It was found that the length changes of the central reticular zone closely followed the applied stretch in time course and magnitude. The results suggest that the length changes of the polar zones are generally similar to those in the central zone.3. There was no evidence of a relative shortening of the central zone in the early phase of maintained stretch, corresponding to the decline of the receptor potential from its dynamic peak to the static level.4. Following release of stretch the central zone returned to its original resting length within a few msec. The rapid return of the spindle was in sharp contrast to the relatively slow exponential decay of the receptor potential. With strong or prolonged stretches the return became slower and resting length was not completely restored until 100-150 msec after release of stretch. No corresponding change in the decay of the receptor potential was seen.5. The results suggest that the early adaptive fall of the receptor potential is not related to differential length changes between the central zone and the polar zones. It seems more likely that the contribution of mechanical factors to the early adaptation of the frog spindle have to be sought at the ultrastructural level.6. The finding that the length changes closely follow the applied stretch suggests that the stimulus in terms of lengthening is transmitted to the endings with little distortion.7. The results suggest that the elastic elements play a dominant role for the transmission of the stimulus to the endings and for the return of the spindle to resting length after release of stretch.