bluuebunny/crossref_metadata_2025_split huggingface dataset:
SOME EFFECTS OF MATERNAL HYPEROXIA AND HYPOXIA ON THE BLOOD GAS TENSIONS AND VASCULAR PRESSURES IN THE FOETAL SHEEP
Authors: Parker H. R. , Purves M. J. 
Published: December 2014

Blood gas tensions, pH and intravascular pressures have been measured at various sites in 22 foetal sheep of gestational age 110–147 days. Umbilical venous oxygen tension did not change significantly with age. The mean pulmonary artery pressure always exceeded that in the aorta and this pressure gradient did not change with age. By contrast the umbilical arterio‐venous pressure gradient increased with age. When the ewe breathed room air, the oxygen difference between uterine artery and umbilical vein was 43–62 mm. Hg. When the ewe breathed 100 per cent 02 umbilical venous P02 rose by 4–15 mm. Hg and umbilical venous pH fell by 0·04–0·07 pH units. There were no consistent changes in foetal heart rate or blood pressures.When the ewe breathed 10 per cent O2 in N2, umbilical venous P02. fell by 7–14 mm. Hg, mean pressures in pulmonary artery and aorta and the pulmonary artery/aortic pressure gradient increased as did the size of the right to left shunt across the ductus arteriosus. Heart rate invariably increased. The oxygen saturation difference between ascending and descending aorta was maintained or increased.These results suggest (1) that factors other than a diffusion barrier to oxygen are responsible for the maternal/foetal oxygen gradient and (2) that, with maternal hypoxia, there is a redistribution of blood flow in the foetus so that as high a tissue P02 as possible is maintained in coronary and cerebral circulations.
INFLUENCE OF INCREASING HEART RATE ON THE ALTERATIONS OF THE CARDIAC VENTRICULAR FIBRE‐CELLS ACTION POTENTIALS INDUCED BY THIAMINE DEFICIENCY
Authors: Rapuzzi G. , Rindi G. 
Published: December 2014

In rats, the action potentials of myocardial fibre‐cells in avitaminosis B1, induced by a deficient diet or by pyrithiamine administration, were measured by fluctuating microelectrodes on hearts in situ at spontaneous and at externally increased heart rate. The increasing of the heart rate enhanced the modifications of the action potentials of spontaneously beating thiamine‐deficient hearts. This suggests that the increased rate may determine a reduction in ion gradients on both sides of the cell membrane.The slowed spontaneous heart rate of thiamine‐deficient rats seems to allow full recovery of the membrane ionic distribution, even if the underlying ion processes were greatly reduced.
THE DIFFERENTIATION OF CONDUCTION VELOCITIES OF SLOW TWITCH AND FAST TWITCH MUSCLE MOTOR INNERVATIONS IN KITTENS AND CATS
Authors: Ridge R. M. A. P. 
Published: December 2014

The difference in conduction velocity (maximum and mean) of the α motor nerve fibres to fast (flexor hallucis longus) and slow (soleus) twitch muscles in adult cats has been verified, and qualitatively similar differences found in adult rabbits and rats. In addition the conduction velocities of α motor nerve fibres to flexor digitorum longus, gastrocnemius medialis and tibialis anticus muscles have been measured in adult cats.Similar measurements (F.H.L. and soleus only), have been made in a series of kittens ranging in age from 8 hr. to 56 days. Although the conduction velocities in the new‐born kitten are one‐tenth those of the adult, the ratio of the conduction velocities of α motor nerve fibres to fast and slow muscles remains approximately constant from birth onwards.It is concluded that at birth the differentiation of the conduction velocities of the α motor nerve fibres to muscles destined to become fast and slow twitch muscles is complete, although at this time the muscles themselves are only beginning to differentiate in terms of contraction times.
GLYCOGEN METABOLISM IN RABBIT KIDNEY UNDER DIFFERING PHYSIOLOGICAL STATES
Authors: Darnton S. Jane 
Published: December 2014

Glycogen, has been assayed biochemically and histochemically in the kidney medulla. It is distributed very discretely in the epithelial cells of the collecting ducts of the papilla.Histochemical and biochemical methods showed that glycogen levels are doubled in diuresis produced by administration of a water‐load or mannitol. In antidiuresis, produced by dehydration or administration of deoxycorticosterone acetate, the glycogen levels are halved as compared with control kidney papillæ. The interstitial mucopolysaccharide structure of the papilla appeared thickened in antidiuresis and was œdematous in diuresis, when compared with sections taken from control kidneys.The glycogen content of the two kidneys of a single animal was not the same. Rabbit kidneys seemed to show a summing action, not working as a pair in parallel but giving a total response appropriate to the water balance of the whole animal.It is suggested that the glycogen could be involved in the provision of energy for active transport processes involved in the transport of ions from the lumen of the collecting ducts to the papillary interstitium or alternatively, or in addition, could also act as a precursor for mucopolysaccharides of the papillary interstitium.
CHOLINESTERASE IN THE SUBMAXILLARY GLAND OF THE RAT AFTER SYMPATHETIC DENERVATION
Authors: Nordenfelt Ivar 
Published: December 2014

Cholinesterase activities have been estimated manometrically in submaxillary glands of the rat after postganglionic sympathetic denervation.In denervated glands there is a significant increase of the break down of the two substrates studied, methacholine chloride and benzoylcholine chloride. This finding is considered to support the hypothesis that in the glands there is collateral sprouting of cholinergic fibres after degeneration of adjacent sympathetic neurones.
THE INDUCTION OF OVULATION IN IMMATURE RATS TREATED WITH PREGNANT MARE'S SERUM GONADOTROPHIN AND HUMAN CHORIONIC GONADOTROPHIN
Authors: Lunn S. F. , Bell E. T. 
Published: December 2014

Studies have been made on ovarian and uterine weight, the occurrence of follicular hæmorrhage and ovulation, and the number of ova shed in the intact immature rat treated with pregnant mare's serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) either alone or in combination.Both PMSG and HCG when given alone were capable of inducing ovulation. This event was associated with uterine stimulation but generally occurred in the absence of marked ovarian weight increase or follicular hæmorrhage.The administration of PMSG followed by HCG produced ovulation over a wide dosage range of both hormones. With low dose levels of PMSG the number of ova shed was independent of the dosage of HCG. However, this was not the case at higher dosages of PMSG, the injection of which was associated with marked ovarian weight increase and follicular hæmorrhage.The mechanism by which PMSG and HCG exert their effects on the ovary is discussed.
LITTER SIZE AND THE DURATION OF PREGNANCY IN MICE
Authors: Dewar A. D. 
Published: December 2014

Analysis of the data from 1246 dated mouse pregnancies revealed an inverse relationship between litter size and gestation period which, however, was not continuously linear over the range of litter sizes as previously shown [Biggers et al., 1963], but was mostly evident as an increase in mean duration with litters below modal size. An additional cause of this effect is suggested.The effect on pregnancy of the administration of œstradiol in amounts likely to cover the ‘physiological’ range was investigated. No reduction in gestation period was observed; with the higher doses, pregnancy was significantly prolonged. The findings do not support the hypothesis that the litter size — gestation period effect involves placental œstrogen.
AN ATYPICAL ACTION OF ACETYLCHOLINE ON THE STRIPED MUSCLE OF THE GUINEA‐PIG ŒSOPHAGUS
Authors: Bartlet A. L. 
Published: December 2014

Acetylcholine produced a longitudinal contraction of the separated externa of the guinea‐pig œsophagus, which was blocked by cocaine or tubocurarine and was partially antagonized by hexamethonium or hyoscine. Acetyl‐β‐methylcholine was almost without action on this preparation.On the whole œsophagus, acetylcholine produced a biphasic contraction which was blocked by cocaine and was partially antagonized by hexamethonium. The fast component of the contraction to acetylcholine was blocked by tubocurarine and was partially antagonized by hyoscine, and the slow component of the contraetion to acetylcholine was blocked by hyoscine and was partially antagonized by tubocurarine. Acetyl‐β‐methylcholine produced a monophasic contraction which was blocked by hyoscine and was potentiated by cocaine.
THE EFFECT OF POSTERIOR PITUITARY HORMONES ON THE CALCIUM, MAGNESIUM, PHOSPHATE AND CHLORIDE METABOLISM OF SHEEP
Authors: Moodie E. W. 
Published: December 2014

The effect of posterior pituitary hormones on the calcium, magnesium, inorganic phosphate and chloride metabolism of five female sheep was studied. Each sheep was subjected to a control observation and to intravenous injections of 450 mU per minute for 30 min. of each of the following: oxytocin (both with and without pretreatment with 5 mg. diethylstilboestrol subcutaneously), pituitary (posterior lobe) extract and vasopressin. Changes in arterial blood concentrations and in absorption from the digestive tract of calcium, magnesium, inorganic phosphate and chloride were estimated.Oxytocin markedly reduced the arterial concentrations of inorganic phosphate and probably increased the absorption of calcium. Vasopressin temporarily increased the arterial blood inorganic phosphate concentration and probably reduced calcium absorption. No effect was observed on the magnesium and chloride metabolism of the sheep as a result of any treatment. The results are discussed in relation to milk fever (parturient hypocalcæmia) in cattle.
THE EFFECT OF REPETITION ON MEASUREMENTS OF POST‐ROTATIONAL TURNING SENSATION AND NYSTAGMUS IN MAN
Authors: Brand J. J. 
Published: December 2014

The effects of repetition on the post‐rotational turning sensation and nystagmus obtained after deceleration from constant angular velocities are described. In a first series of tests decelerative stimuli from constant angular velocities of 60, 30, 15 and 7·5°/sec. were given to two groups of subjects but in a different order, and the mean responses obtained from both groups showed that habituation might occur in the course of a single test.In a second series with a different group of subjects, the test was repeated on each of nine consecutive days. The effects of habituation were again seen and there was a progressive decline in the responses which were obtained. The administration of l‐hyoscine ( 0·7 mg. base) 1 hr. before the test on the sixth day produced little additional effect in habituated subjects.
EFFECT OF ISOXSUPRINE HYDROCHLORIDE ON THE SURVIVAL RATE OF DOGS SUBJECTED TO ACUTE BLOOD LOSS
Authors: Sharma P. L. 
Published: December 2014

In dogs anæsthetized with pentobarbitone sodium, hæmorrhagic shock was produced by rapid bleeding. The blood pressure was maintained at 35 ± 5 mm. Hg for 4 hr., and then the shed blood was returned to the animal. Animals alive at the end of a 72‐hr. observation period were considered as survivors. In the control group only one out of ten dogs survived. All the animals developed severe watery diarrhœa Isoxsuprine hydrochloride 0·3 mg./kg. administered intravenously in 10 ml./kg. of normal saline 2 hr. after the onset of oligæmic hypotension increased the survival rate from 1/10 in the control group to 7/10 in the treated group. Only two dogs developed mild diarrhœa. The incidence of ventricular arrhythmias during fluid replacement was reduced from 7/10 to 2/10. However, when this drug was administered 4 hr. after the onset of oligæmic hypotension there was no improvement in the survival rate as compared to the control group but death was significantly delayed in the treated cases. The incidence of ventricular arrhythmias was reduced from 7/10 to 4/10. All the animals developed severe watery diarrhœa.The beneficial effect of isoxsuprine may be due to improved tissue perfusion resulting from vasodilatation and an increase in the volume of circulating fluids produced by the concomitant infusion of normal saline to sustain the blood pressure above 30 mm.Hg. Another factor might be the positive inotropic action of this drug.It is suggested that isoxsuprine may prove useful in the management of oligæmic shock in man.
THE EFFECT OF DIETARY FAT LOAD ON THE SIZE AND COMPOSITION OF CHYLOMICRONS IN THORACIC DUCT LYMPH
Authors: Fraser R. , Cliff W. J. , Courtice F. C. 
Published: December 2014

Chylomicrons of Sf 〉 400 and lipoproteins of Sf 12‐400 were separated by ultra‐centrifugation from samples of thoracic duct lymph collected from rabbits fed for 1 to 2 weeks previously on diets containing 5 per cent and 30 per cent corn oil or butter and from rats given a single intragastric dose of 0·5 ml. corn oil.The size of these particles after corn oil was determined by electron microscopy following fixation in osmium tetroxide. In rabbits on the low fat diet the mean diameter of chylomicrons was 960 Å with half the triglyceride in particles of diameter greater than 1400 Å; on the high fat diet the mean diameter was 1435 Å with half the triglyceride in particles of diameter greater than 2700 Å. In rats the mean chylomicron diameter was 1094 Å in the early phase of fat absorption with half the triglyceride in particles of diameter greater than 1320 Å. These figures increased to 2105 Å and 3600 Å respectively at the peak of fat absorption.The relationship between the chemical composition of these complexes and their actual size suggests that phospholipid is uniformly distributed on the surface, each phospholipid molecule occupying approximately 65 Å2.Although meaningful electron micrographs of butter chylomicrons could not be obtained, determinations of the triglyceride : phospholipid ratios indicate that, as with the corn oil‐fed animals, the chylomicrons from the rabbits fed 30 per cent butter are on the average larger than those from the animals fed 5 per cent butter.
AUGMENTED RENAL EXCRETION OF CALCIUM AND MAGNESIUM IN SHEEP AFTER FEEDING
Authors: Stacy B. D. 
Published: December 2014

When penned sheep were given their daily food, there were marked increases in the rate of urinary excretion of calcium and magnesium, and a sharp fall in urinary pH. There were also post‐prandial increases in the plasma levels of calcium and magnesium, and a fall in blood pH and plasma bicarbonate concentration. By analogy with the effects of metabolic acidosis in other species, it seemed likely that the hypercalciuria in the sheep was causally related to the change in acid‐base balance after feeding.It was concluded that the excretory changes reflected the response of the kidney to intercompartmental shifts of body fluid following the potent stimulus to salivary secretion during eating.In these experiments, the excretion of inorganic phosphate was extremely low, and the absence of this urinary buffer was probably an important factor contributing to the abrupt and considerable fall in urinary pH after feeding.
THE EFFECTS OF VARIATIONS IN WATER OR POTASSIUM INTAKE ON THE RENAL EXCRETION OF POTASSIUM IN SHEEP
Authors: Scott D. 
Published: December 2014

By infusing water into the rumen of sheep receiving a fixed potassium intake the relationship between excretion of potassium and urine volume was examined.Both the osmotic pressure and the concentration of potassium in the urine fell as the urine volume was increased, but the amount of potassium excreted was not affected by urine volume provided this was above 1·0 to 1·5 1./day.When the potassium intake of sheep was increased through the range 236–1186 m.equiv./day there was a proportional increase in the amount of potassium excreted in the urine.Between 236 to 889 m.equiv./day there was no change in the amount of potassium filtered across the glomerulus, but above this the amount of potassium filtered across the glomerulus increased. This result suggests that when potassium intake is very high a proportion of the potassium filtered across the glomerulus may augment the secretory process in eliminating dietary potassium excesses.
PLASMA OSMOLALITY AND SALT GLAND SECRETION IN THE DUCK
Authors: Ash R. W. 
Published: December 2014

Secretion by the supra‐orbital glands of conscious Aylesbury ducks began when plasma osmolality and [Na+] were increased by 2–8 per cent after oral administration of hyperosmotic NaCl solution. Peak rates of secretion occurred when these parameters were elevated by 8–19 per cent. Oral administration of water in volumes sufficient to decrease plasma osmolality and [Na+] below these values abolished or reduced the flow of secretion.Comparable or larger increases in plasma osmolality produced by hyperosmotic KCl solution administered orally or by intravenous injection of urea or dextrose failed to evoke secretion.Intravenous injection of hyperosmotic sucrose or mannitol increased plasma osmolality and decreased plasma [Na+] but evoked secretory responses which declined although plasma osmolality remained increased.An osmotic component appears to be involved in the secretory mechanism of the salt glands but the relation between secretion and plasma osmolality is not simple and probably depends on the permeability of certain cells to different solutes.
THE INFLUENCE OF LUNG SHRINKAGE ON BREATH HOLDING TIME
Authors: Godfrey S. , Edwards R. H. T. , Warrell D. A. 
Published: December 2014

The influence of lung shrinkage on the breath holding time was studied in three normal males. The rate of shrinkage was increased two to three fold either by slow expiration or by reducing gas density in a hypobaric chamber. For any given lung volume the relationship between breath holding time and pCO2 was defined by a rebreathing method which allowed breath holds to be performed at progressively increasing levels of pCO2. Hypoxia was avoided throughout and the ventilatory response to CO2 remained constant irrespective of ambient pressure.The breath holding time for any given pCO2 was usually longer the larger the lung volume. Increasing the rate of lung shrinkage by either method did not alter the relationship between breath holding time and pCO2. There was no constant relationship between the pCO2 and the lung volume at the breaking point of a breath hold. These findings are discussed in the light of previous work and it is concluded that the sensation arising during breath holding cannot be fully explained in terms of any combination of pCO2, lung volume and lung shrinkage.
THE EXTERNAL WATER EXCHANGES OF NORMAL LABORATORY DOGS
Authors: O'Connor W. J. , Potts D. J. 
Published: December 2014

Bitches on a fixed food intake were kept in metabolism cages. Urinary volume, drinking and body weight were measured each day and loss of water by evaporation calculated.The mean evaporative loss of individual dogs varied from 8 to 116 g/kg/day; this could be accounted for by differences in the behaviour of the dogs resulting in different amounts of activity in the cages. Evaporative loss also varied widely from day to day. In direct observations in the laboratory evaporative loss of dogs at rest was about 1 g/kg/hr and this was increased by mild exercise to about 5 g/kg/hr. The environmental conditions were never warm enough to significantly affect evaporative loss.The amount of water drunk by each dog varied from 4 to 109 ml./kg/day; the active dogs with high evaporative loss drank most water, the water intake thus approximately matching evaporative loss. Details of the drinking were recorded by a meter. Much of the drinking occurred during the times of the day when the animals were most active, and consisted of small drinks of 30–100 ml. Water given by stomach tube inhibited drinking for as long as 23 hr. A period of water deprivation increased drinking, usually in the form of large drinks of over 100 ml.The mean urine volume varied in different periods of observation from 80–380 ml./day; the urine was of high concentration, about 1600 m‐osmole/l. The volume was not related to activity of the dogs and varied little from day to day. The main determinant of the volume of the urine appeared to be the rate of excretion of solutes which varied very little because of the fixed daily intake of food. There were only a few days on which the urine was of high volume and dilute; in discussion it is stated that this means that varying release of antidiuretic hormone played little part in determining the urine volume and in the regulation of water balance.A small dose of water (about 5 ml./kg body weight) given by stomach tube always prevented drinking; a larger dose was required to produce water diuresis. This explains why water diuresis rarely occurred in dogs drinking naturally.Water balance was achieved because the evaporative loss due to variable activity was matched by drinking.
THE DISTRIBUTION OF THE PRINCIPAL INORGANIC IONS IN SEMEN FROM THE VAS DEFERENS OF THE DOMESTIC FOWL AND THE CONTENT OF CARBON DIOXIDE IN THE SEMINAL PLASMA
Authors: El Jack M. H. , Lake P. E. 
Published: December 2014

The distribution of sodium, potassium, calcium and magnesium between the spermatozoa and plasma in the semen of the vas deferens of the domestic fowl has been determined by atomic absorption spectrophotometry. Chloride in the seminal components was analysed by an electrometric titration method and carbon dioxide in the seminal plasma was analysed using gas chromatography.The contents of potassium and magnesium were much higher, and those of sodium, calcium and chloride lower in the spermatozoa than in the seminal plasma. The amount of sodium in the plasma of the vas deferens was about the same as that in blood plasma, but the amounts of potassium and magnesium were greater in the seminal plasma. The amount of chloride was small in the seminal plasma and its significance in relation to the ionic balance in the fluid is discussed.
RENAL EXCRETION OF POTASSIUM AND ACID BY SHEEP
Authors: Scott D. 
Published: December 2014

Infusion of HCl into the rumen of sheep led to a fall in the pH of the urine and to the reabsorption of bicarbonate from the urine. Excretion of acid in the urine rose until it was about equal to the amount of acid given into the rumen. There was very little titratable acid present in the urine and over 90 per cent of the acid excreted was in the form of ammonium ions. The limitation in the excretion of titratable acid seems to be related to the observation that sheep normally excrete very little phosphorus (as phosphate) in the urine.The renal response to acidosis in sheep was not influenced by the amount of potassium in the diet.
NERVOUS TRANSMISSION IN THE SUPERIOR CERVICAL GANGLION OF THE THIAMINE‐DEFICIENT RAT
Authors: Perri V. , Sacchi O. , Casella C. 
Published: December 2014

The amplitude of the post‐ganglionic potential was measured in isolated preparations of the superior cervical ganglion from rats at different stages of thiamine deficiency.At low frequency stimulation (0·5/sec) a decrease in the post‐ganglionic potential amplitude was not observed until the final stages of thiamine deficiency. At high frequency stimulation (20/sec) the post‐ganglionic potential of the thiamine‐deficient rats showed an early and much more pronounced decrease in comparison with that observed in both normal animals and pair‐fed controls.The amplitude and conduction velocity of the different components of the sympathetic cord action potential were unaffected by thiamine deficiency.