bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glucose metabolism during ontogeny of intestinal active sugar transport in the chick
Authors: Bogner Phyllis Holt , Braham Ann H. , McLain Paul L. 
Published: December 2014

1. Glucose transport, uptake, utilization, and lactate production by intestinal slices from embryos and young chicks have been determined by means of the in vitro tissue accumulation method. Changes in these parameters with age, after feeding, and in the presence of phlorrhizin have been measured, in most cases, under both aerobic and anaerobic conditions.2. The embryonic intestine, 3 days before hatching, took up and utilized only a negligible quantity of glucose from the incubating medium and net lactate production was limited. The transport and utilization of exogenous sugar thus seem to be minimal at this age.3. On the day of hatching, the intestine concentrated and utilized glucose, and lactate production was significant as was the inhibition of glucose uptake by phlorrhizin. This capacity to metabolize exogenous sugar appears to be consequent to onset of function of the sugar transport mechanism just before hatching.4. At 2 days of age intestinal slices concentrated and utilized more glucose than at 0 days of age, if the chicks were not fed. After eating, glucose transport was decreased while lactate production was enhanced. Feeding schedules thus influence sugar transport and metabolism by the young chick intestine.5. The metabolic parameters measured showed essentially the same relationships in intestinal slices from 8‐ and 36‐day‐old chicks as in 2‐day‐old birds. Although there were indications that intestinal maturation continues well into post‐natal life, the most striking changes in functional capacity, observed in these studies, occurred during the several days around hatching.
Orientational selectivity of the human visual system
Authors: Campbell F. W. , Kulikowski J. J. 
Published: December 2014

1. It is known that an object is less detectable when it is viewed against a background containing structures similar to the object. The effect of changing the orientation between the object and background is investigated.2. Gratings of variable contrast were generated on two oscilloscopes; these were superimposed optically. The angle of orientation between them could be changed. The threshold of one grating, the test grating, was determined in the presence of the other, the masking grating.3. When the gratings were presented with the same orientation (and locked in phase) the increment threshold of the test grating was found to be proportional to the suprathreshold contrast of the masking grating.4. As the angle between the test and masking gratings was increased the masking effect fell exponentially.5. At 12° on either side of a vertical test grating the masking effect was reduced by a factor of two with respect to its maximum value. This angle was independent of the contrast level of masking, the focus, and also the phase coherence of the masking grating.6. If the test grating was presented obliquely the effect of masking was slightly less.7. The narrow orientationally tuned channels found psychophysically by this masking technique are compared with the orientationally sensitive cells discovered electrophysiologically in the visual cortex of the cat.
The effect of beta adrenergic receptor blockade on the vasodilator response in the forearm to voluntary hyperventilation
Authors: Brick I. , Hutchison K. J. , Roddie I. C. 
Published: December 2014

1. Blood flow was simultaneously measured by venous‐occlusion plethysmography in both forearms of ten healthy men.2. Voluntary overbreathing to produce about 8 times the resting ventilation caused a vasodilatation similar in both forearms.3. When one forearm was treated with an intra‐arterial infusion of propranolol, a beta adrenergic blocking agent, the vàsodilator response was reduced by an average of 28%, the reduction was significant (P < 0·01).4. The failure of propranolol to abolish the vasodilator response was not due to incomplete block of beta adrenergic receptors since the dose of propranolol used reversed the vasodilator response to an intravenous infusion of adrenaline.5. The results suggest that the vasodilator response to voluntary hyperventilation can be explained partly, but not entirely, by the release into the circulation of an adrenaline‐like substance.
Units in the cerebral cortex of the anaesthetized rat and the correlations between their discharges
Authors: Holmes O. , Houchin Jane 
Published: December 2014

1. Extracellular records have been made of spontaneous unitary activity in the cortex of the anaesthetized rat. If the animal is anaesthetized with sufficient urethane almost to abolish reflex contractions of leg muscles when a hind paw is stimulated, two types of spontaneously active unit are found. One type of unit is found in all areas of the cortex which have been studied, and gives high voltage discharges. The other has only been found in restricted areas of cortex and gives low voltage discharges.2. The activity of the former type of unit has been analysed. In the unstimulated animal, groups of relatively frequent discharges are separated by periods of quiescence. Apart from this, the discharge pattern appears irregular on naked‐eye examination. Synchronous with these periods of frequent discharge, the electrocorticogram exhibits rapid oscillations. Peripheral stimulation of the animal can modify the pattern of discharge of this type of unit. Details of these observations are described.3. The results are described of experiments in which simultaneous records have been taken from pairs of units in the cerebral cortex. The intensity of correlation between the two units has been measured as a function of temporal displacement (lag) between the two records.4. With fairly deep urethane anaesthesia, the highest correlation between the two unitary discharges occurs at zero lag if the two units are close together or if they are far apart but in the same coronal line, e.g. if the recording electrodes lie in homologous areas of the two cerebral hemispheres. If one unit is in the anterior pole of a hemisphere and the other in the posterior pole, the discharges are usually synchronous. However, it has sometimes been found that the anterior of the pair of units discharges impulses which precede those of the posterior unit by up to 100 msec. The highest intensity of correlation is then appropriately displaced to 100 msec.5. The correlation fluctuates rhythmically with a period of 1·8‐2 sec, slowly damps out and is symmetrical around the point of highest correlation.6. Increasing the sensory bombardment of the cortex reduces or abolishes the correlation between the activity of pairs of units.7. Under Nembutal anaesthesia sufficient to abolish reflex contractions of leg muscles when a hind paw is pinched, no spontaneous cortical unitary activity has been found. When anaesthesia is ligher, spontaneous activity does occur and consists of bursts of up to six impulses at a frequency of 300‐500/sec. When simultaneous records from two units have been made, no correlation has been found between their activity.
An upper limit to the number of sodium channels in nerve membrane?
Authors: Moore J. W. , Narahashi T. , Shaw T. I. 
Published: December 2014

1. A small volume of artificial sea water containing 300 n
M tetrodotoxin (TTX) was applied successively to seven lobster nerve trunks and the cumulative uptake of toxin investigated by bio‐assay.2. Light and electron microscopy indicated that the nerve trunks had a total axonal area of 0·7 × 104 cm2/g.3. Sodium analysis gave a sodium space for the nerve trunks of 30%.4. The amount of toxin taken up by the cells in 1 g of nerve is less than 1·6 × 10−11 moles.5. It is argued that there are probably fewer than 13 sodium channels/μ2 axon in lobster nerve.
Active sodium transport by the colon of Bufo marinus: stimulation by aldosterone and antidiuretic hormone
Authors: Cofré G. , Crabbé J. 
Published: December 2014

1. The isolated colon of Bufo marinus transports sodium actively from the mucosal (lumen) to the serosal side, and this transport is expressed quantitatively by the short‐circuit current.2. Upon dilution of sodium in Ringer solution on the mucosal side of the preparation, short‐circuit current remained a fair expression of sodium transport from mucosa to serosa.3. In view of this, the relation between short‐circuit current and dilution of sodium of the luminal side was examined. This relation was curvilinear, which suggests the intervention of a saturable step in the transfer of sodium from lumen to serosal surface of colon.4. The relation between short‐circuit current on the one hand, and the amount of sodium drawn from the luminal side and recovered in the membrane (‘active sodium transport pool’) on the other hand, appeared (almost) linear instead. This is meant to indicate that the ‘pump’ operates far from capacity. Hence, the observed saturation of sodium transport, when concentration of sodium on the mucosal side was increased, probably occurs at the mucosal border of the preparation.5. After treatment with aldosterone, the ‘active sodium transport pool’ and short‐circuit current increased to the same extent, from which it is inferred that the hormone merely allows sodium easier access to the ‘pump’ which would react in proportion. Consequently, no direct influence of aldosterone on the ‘pump’ proper need be postulated.6. Upon exposure of the colon to antidiuretic hormone, there were (modest) increases of short‐circuit current and of osmotic water flow across the wall of the organ.
The experimental production of watery vacuolation in the acinar cells of the submandibular gland
Authors: Tapp R. L. , Trowell O. A. 
Published: December 2014

1. Watery vacuolation in the acinar cells of the rat submandibular gland is described. The vacuoles are cytoplasmic, membrane‐walled, and 2‐20 μ in diameter. They are visible in living cells and appear to contain a watery fluid.2. Vacuolation occurred regularly in the following experimental situations: (1) in vitro—under anoxic conditions (2) post mortem—in animals killed by anoxia, and (3) in vivo—during secretion.3. By in vitro experiments it was shown that vacuolation occurs only when the cells are both anoxic and exposed to an excess of extracellular fluid containing calcium and bicarbonate. It was further shown that vacuolation is reversible in oxygen and that both its development and recovery are temperature dependent.4. Evidence is presented that the vacuolation is not a degenerative or necrotic change, that it is accompanied by the entry of fluid into the cells, and that it is not caused by simple osmosis.5. The mechanism of vacuolation and its possible relation to secretion are discussed. It is suggested that vacuolation represents an imbalance between the ingestion and secretion of water and salts.6. Similar vacuoles, apparently produced by the same mechanism, were observed in the acinar cells of the parotid gland and the pancreas of the rat.7. The close similarity of this vacuolation to that previously described in rat liver cells was noted.
Mechanics of horizontal movement of the human eye
Authors: Childress D. S. , Jones R. W. 
Published: December 2014

1. The mechanics of the muscle—eyeball system of the human has been re‐investigated by careful examination of the motion of the eye after it is mechanically adducted and released by means of a suction contact lens attached to it.2. Orbital stiffness during adduction is found to be about 1·25 g/deg which is near the value of 1·2 g/deg reported by Robinson (1965) for abduction. However, the results also show that the stiffness decreases to 0·65 g/deg after approximately 5° of adduction.3. It is concluded that for horizontal motion the globe may be considered as being in series with an elastic component which has a stiffness of 9·0 g/deg. This series elastance, arising from the extraocular muscles, muscle tendons, and from other orbital tissue appears to increase in stiffness as muscle innervation increases.4. The experiments show that the muscle—eyeball system of the human is heavily damped which confirms the results of Robinson (1964).5. Evidence is presented which indicates that the extraocular muscles are dominant factors in horizontal eye motion.
Receptive fields and trigger features of ganglion cells in the visual streak of the rabbit's retina
Authors: Levick W. R. 
Published: December 2014

1. A survey of the properties of retinal ganglion cells in the central part of the rabbit retina has been carried out.2. The five types of unit previously encountered in the peripheral retina were also found in the central region. Their receptive fields were smaller, and tended to be oval‐shaped with the long axis horizontal.3. In addition, three new types were discovered: orientation‐selective cells, local‐edge‐detectors, uniformity‐detectors.4. Orientation‐selective cells were sensitive to either vertically or horizontally extended targets. Analysis suggested they were modified concentric units with an incomplete antagonistic surround.5. Local‐edge‐detectors responded to the appearance or movement of a contrasting border within the receptive field. They were inhibited by similar stimulation of the region surrounding the receptive field. Detailed attention was given to the demonstration of edge‐detection.6. Uniformity detectors had a relatively high level of ongoing activity in the absence of stimulation. All forms of stimulation (lights flashed on or off, movement of darker or lighter targets) produced a diminution or cessation of ongoing activity.7. The results are compared with behaviour described in other species.
The regional distribution of the nerve‐stimulating phosphopeptide (nerveside, substance B) in the central nervous system
Authors: Toh C. C. 
Published: December 2014

1. The nerve‐stimulating phosphopeptide, nerveside, is present mainly in the cerebrum and brain stem, while the cerebellum contains only a trace amount of it.2. Nerveside is uniformly distributed over all parts of the cerebral cortex.3. The cerebral cortex contains the greatest concentration of nerveside. If the nerveside activity of 1 g cerebral cortex is expressed as 100 then the relative activities of the other parts of the
C.N.S. are hippocampus 41, caudate nucleus 21, diencephalon (without hypothalamus) 24, midbrain 19, pons 7, medulla 12 and cerebellum 6.4. The nerveside activity of the hypothalamus is the same as that of the cerebral cortex.5. The pattern of distribution of nerveside in the
C.N.S. suggests that it may be part of a corticipetal or corticifugal system.
The time course of the effect of thyroid hormones upon basal oxygen consumption and plasma concentration of free fatty acid in rats
Authors: Myant N. B. , Witney Sarah 
Published: December 2014

1. Basal O2 consumption and plasma free fatty acid (FFA) concentration were measured in normal and hypothyroid rats at various intervals after the initiation of a course of treatment with thyroid hormones.2. A significant rise in basal O2 consumption was detectable in both groups of rats before there was any change in plasma FFA level.3. It is concluded that the stimulatory effect of thyroid hormones on the basal O2 consumption of the whole animal is not mediated entirely by a rise in plasma FFA level.
The effect of 5‐hydroxytryptamine on the potassium exchange of human platelets
Authors: Born G. V. R. 
Published: December 2014

1. The concentration of potassium in platelets freshly isolated from nine persons was 74 ± 4·8 μmole/1011 platelets (mean ±
S.E.M.).2. The influx of potassium into platelets from citrated plasma at 37° C, estimated with the use of 42K, was 18·3 ± 1·6 n‐mole/sec. 1011 platelets.3. When plasma contained 5‐hydroxytryptamine (5‐HT) at a concentration of about 5 μg/ml., the influx of potassium into platelets was increased for as long as they took up 5‐HT. This effect was absent when the concentration of 5‐HT was either lower (2 μg/ml.) or much higher (50 μg/ml.).4. The concentration of 5‐HT in the platelets did not affect their potassium flux.
Membrane properties of the smooth muscle of guinea‐pig ureter
Authors: Kuriyama H. , Osa T. , Toida N. 
Published: December 2014

1. The membrane properties of the guinea‐pig ureter were studied in physiological Krebs solution by intra‐ and extracellular stimulating methods.2. The mean membrane potential was 50 mV. Action potentials triggered by external stimulation were composed of repetitive spikes and a plateau phase.3. The effects of intracellular polarization on the membrane activity elicited by extracellular stimulation were observed. Anodal polarization enhanced the amplitude and the maximum rate of rise of the spike while cathodal polarization reduced them. The number of the spikes, the duration and amplitude of the plateau phase were not changed by polarization of any direction.4. The spikes triggered by intracellular stimulation were mostly graded, but repetitive spikes sometimes continued even after cessation of the stimulation. The effective membrane resistance was 15‐23 MΩ and the time constant was 2‐3 msec.5. Conduction velocity (V), chronaxie, time constant (τ) and space constant (λ) of the tissue were measured by extracellular stimulation. These values were as follows: V, 3‐6 cm/sec; chronaxie, 20‐40 msec; τ, 200‐300 msec; λ, 2·5‐3 mm. The conduction of excitation might be related to the cable properties of the tissue.6. The relative refractory period measured by extracellular stimulation was as long as 30 sec. During the relative refractory period dissociation of the slow depolarization and the spikes was observed by successive stimuli.7. The plateau phase was prolonged and the frequency of the spontaneous discharges was increased by treatment with Ba2+. Tetrodotoxin had no effect on spike activity nor on the plateau phase, but Mn2+ blocked the membrane activity.
Cardiac sympathetic adrenergic pathways in which synaptic transmission is blocked by atropine sulphate
Authors: Brown A. M. 
Published: December 2014

1. Stimulation of the thoracic sympathetic nerve trunk caused a rise in arterial blood pressure and heart rate which was reduced but not abolished during the infusion of hexamethonium chloride, pentolinium tartrate, mecamylamine or tetraethylammonium chloride.2. Preganglionic stimulation no longer elicited a synchronous sC elevation in the post‐ganglionic nerves. The persistent blood pressure and heart rate response was associated with an asynchronous discharge in these nerves.3. Both the persistent response and the asynchronous discharge were abolished by the intravenous injection of atropine sulphate in doses of 30 μg/kg.4. Atropine had no effect on spike amplitude or shape, conduction velocity or frequency response in either the pre‐ or post‐ganglionic nerve trunks. Nor did it affect the rise in blood pressure and heart rate evoked by stimulation of the post‐ganglionic cardiac sympathetic nerves.5. It is concluded that atropine partially blocked synaptic transmission in cardiac sympathetic adrenergic pathways.
Determination of plasma kinin and kininogen levels in man
Authors: Brocklehurst W. E. , Zeitlin I. J. 
Published: December 2014

1. A method for the estimation of free plasma kinin and kininogen is described, which is suitable for samples of blood taken in hospital.2. The method permits the assay of very low levels of kinin and substantially eliminates errors due to the presence of amines and other interfering substances.3. In normal subjects the mean value of free kinin is 2·8 ng (bradykinin equivalent)/ml. plasma, and 6·1 μg kininogen/ml.4. In vasovagal fainting, carcinoid flush, and dumping syndrome, during the phase of peripheral vasodilatation, the free kinin exceeds 10 ng/ml., and is often in excess of 30 ng/ml.5. Sudden release of free kinin is accompanied by a fall in kininogen level.
Effects of gestation and prenatal asphyxia on pulmonary surface properties of the foetal rabbit*
Authors: Humphreys P. W. , Strang L. B. 
Published: December 2014

1. The pulmonary surface properties of foetal rabbits were studied after delivery by Caesarean section at 26‐30 days and after normal delivery at term (31 days).2. Quasi‐static pressure—volume curves were defined for the lungs and the surface properties of the same lungs were further studied both by the bubble‐stability method and by means of a surface balance and trough. Results given by each method are compared and discussed.3. At the 26th day of gestation the pulmonary surface properties, characteristic of the animal at term, were not yet present. These properties were first evident on the 28th day.4. A period of 16 min intense prenatal asphyxia on the 28th day of gestation failed to produce a change in pulmonary surface properties.
The distribution of acetylcholine in normal and in regenerating nerves
Authors: Evans C. A. N. , Saunders N. R. 
Published: December 2014

1. The distribution of acetylcholine (ACh) in various nerves which had been regenerating for different periods after crushing has been compared with that in uncrushed nerves.2. Normal ventral roots from cats contained 78·1 ± 22·7 (
S.D.) μmole ACh/kg (blotted wet wt.); rabbit ventral roots contained 48·0 μmole/kg ± 19·0 (
S.D.) and rabbit sciatic nerves 16·6 ± 7·3 (
S.D.) μmole/kg. In the sciatic nerves the distal cm of 5 cm lengths taken from the thigh contained 30% more ACh than the most central cm portion. Possible explanations for this difference have been discussed.3. After both sciatic nerves and ventral roots had been crushed, there was an initial build‐up (4 times control) of ACh central to the lesion and a decline (¼ control) distal to the lesion. These changes were maximum around 5 days after crushing. In sciatic nerves in which long periods of regeneration were investigated, the central build‐up fell off to 1½ times control by 25 days and the distal decline reversed to 2 times control in about 10 days. It then again decreased towards the control level by 25 days after crushing. These changes have been discussed in relation to the morphological changes which occur in a nerve following crushing.4. A peak of ACh content moved distally along the nerve from the crushed region at a rate of 1·0‐1·5 mm/day. This was considered to represent an average rate of regeneration of the bulk of the axons. The amplitude of the peak declined progressively with time in the more distal parts of the nerve, probably because of dispersion as axons regenerated at different rates.