bluuebunny/crossref_metadata_2025_split huggingface dataset:
PERFUSION OF THE ISOLATED MAMMARY GLAND OF THE GOAT
Authors: Linzell J. L. , Fleet I. R. , Mepham T. B. , Peaker M. 
Published: December 2014

Improvements to a previously reported technique for the perfusion of isolated goat mammary glands are described. Secretion of milk of relatively normal composition in vitro has been maintained at approximately 50% of the in vivo rate for about 12 hr. Factors found to be important for successful perfusion are a normal rate of mammary blood flow, the provision of adequate glucose, acetate and amino acids, and the inclusion in the circuit of an efficient oxygenator and dialyser.Contrary to earlier results successful perfusions have been performed with glands from anaesthetized and from shot animals, although removal of glands from the tranquillized animal under spinal anaesthesia is still preferred. There was a marked dependence of milk secretion rate on the rate of blood flow below a critical value, but at supra‐normal flows there was no correlation between these variables. Evidence has been obtained suggesting that kinins or similar substances may be formed during perfusion.The specific dependence of milk secretion on glucose is again stressed. Other carbohydrates sustained oxygen consumption similar to that shown with glucose, but by contrast did not support the secretion of water, a small amount of milk low in lactose but high in fat and protein being produced. Although milk fat secretion was dependent on the provision of acetate, the omission of β‐hydroxybutyrate, lactate and neutral fat (all shown to be absorbed by the gland in vivo) from the substrate mixture did not seriously impair milk fat secretion in vitro. Amino acids were shown to be necessary for normal rates of milk protein secretion, but the alteration of the substrate mixture to correspond to the amino acid absorption observed in vivo produced no significant change in milk secretion from that observed when amino acids were infused at rates corresponding to their occurrence in casein. The infusion of B vitamins and various hormones had no effect on milk secretion. Perfusions carried out with a conscious goat in circuit were no more successful than the completely in vitro system, but glands grafted onto recipient goats (even males) following complete removal from the donors produced substantially more milk than in vitro preparations.In some experiments milk [Na] and [Cl] increased during perfusion while [K] and [lactose] decreased, these trends being apparent in milk secreted before perfusion was begun and being probably due to the oxytocin used to produce milk ejection. In other experiments milk [Na] and [Cl] showed little change but [K] and [lactose] tended to rise.Possible factors limiting the performance of perfused organs are discussed.
RESPIRATORY CHANGES INDUCED BY THE IMMEDIATE BLOCK OF NERVOUS CONDUCTION IN THE VAGUS NERVES
Authors: Sant'Ambrogio Giuseppe , Camporesi Enrico , Sellick Hilary , Mortola Jacopo 
Published: December 2014

A differentiation of vagal respiratory reflexes has been obtained in rabbits by the application of a D.C. current of various intensities to both the vagus nerves. It has been possible to abolish the inflation reflex while Head's paradoxical response to inflation was revealed without eliminating the deflation reflex. The coexistence of Head's paradoxical reflex and the deflation reflex may suggest that these reflex responses originate through activation of the same receptors.The inspiration which follows the immediate withdrawal of vagal afferent inflow has a much longer duration than the following ones: this seems to suggest that some of the inhibitory influence coming through the vagus is taken over, after the duration of the first breath, by some other inhibitory mechanism.A vagal ‘block’ introduced at the same time as an occlusion of the airways leads to an inspiratory effort which is much longer than when occlusion only is performed. This could be ascribed to the blockade of some vagal fibres normally active at FRC which should have an overall inhibitory influence on inspiratory activity.
INTRARUMINAL AND SYSTEMIC RESPONSES TO VARIATIONS IN INTAKE OF SODIUM AND POTASSIUM BY SHEEP
Authors: Warner A. C. I. , Stacy B. D. 
Published: December 2014

A maintenance diet providing about 200 m‐equiv potassium and 30 m‐equiv sodium per day was given to sheep; on this intake sodium and potassium balances were small and positive. When potassium chloride was added to the diet to provide a total of about 700 m‐equiv potassium per day, the potassium content of the rumen increased and the sodium content decreased, apparently due to an increased rate of absorption of sodium across the rumen wall. The rate of excretion of sodium in the urine was increased for about 4 days, giving a considerable negative sodium balance; the extra amount excreted was of the same order of magnitude as the loss from the rumen. Water consumption increased by 0·5–0·9 l./day, without change in water balance. The apparent potassium balance increased by an amount much greater than could be accounted for by changes in rumen content.When the potassium content of the diet was returned to its initial value there was an intense retention of sodium by the kidney, with signs of increased adrenocortical activity and a strongly positive sodium balance for about 14 days. During this time the sodium content of the rumen increased and the potassium content decreased slowly to about initial values. Water consumption retumed to normal and the potassium balance dropped, often to low or even negative values for a while.The mechanisms apparently permitting the rumen to dominate the response of the whole animal to changes in the electrolyte content of the diet are discussed.
LUNG FUNCTION AND EXERCISE PERFORMANCE OF HEALTHY CARIBBEAN MEN AND WOMEN OF AFRICAN ETHNIC ORIGIN
Authors: Miller G. J. , Cotes J. E. , Hall A. M. , Salvosa C. B. , Ashworth A. 
Published: December 2014

Lung function, body muscle, levels of habitual activity and exercise performance were measured in young adult men and women of African origin in Jamaica and Trinidad. The results were compared with those of men and women of European descent studied by the same methods in Leeds, England.Lung function was very similar in Jamaicans and Trinidadians. Vital capacity was smaller in Africans than in Europeans and smaller in women than in men, even after standardization for age and height. There was no sex difference in residual volume. The single breath transfer factor was larger in men than women but there was no ethnic difference. The effects of age and height on lung function appeared to be similar in the two ethnic groups. Exercise tidal volume relative to minute volume was larger in Europeans than in subjects in the Caribbean but this difference disappeared when allowance was made for vital capacity.When allowance was made for differences in body muscle the heart rate during standard sub‐maximal exercise was lowest in Jamaican men and highest in Trinidadian men and Jamaican women, with English men and women intermediate. These differences may have been related to the levels of habitual activity in these groups, which were judged to have been highest in the Jamaican men.Maximal heart rate during exercise was similar in all male groups but relative to body muscle, maximal exercise performance was impaired in the subjects in the Caribbean. It is postulated that this may have been owing to the higher temperatures in Jamaica and Trinidad than those in England.We conclude that while ethnic and sex differences affect ventilatory capacity and tidal volume these are less important for maximal oxygen uptake than habitual activity, environmental temperature and body muscle.
THE INFLUENCE OF URETER LIGATION AND DIURESIS ON RENAL LYMPH FORMATION
Authors: McIntosh G. H. 
Published: December 2014

Ligation of the ureter in sheep was followed by a 2‐12‐fold increase in lymph flow from the kidney during the first 24 hr, after which flow rates returned slowly to preocclusion levels. There was a fall in protein concentration in lymph, and a slight rise in the ratio of lymph concentration to plasma concentration of urea, potassium and magnesium. A similar rise in lymph flow was observed during the intravenous infusion of large amounts of Ringer‐Locke solution. Diuresis produced by Frusemide injections or mannitol infusion was not accompanied by any change in lymph flow.When labelled inulin and hippuran were infused intravenously into a sheep with the left ureter ligated, the ratio of lymph concentration to plasma concentration of these substances was significantly higher than for the unobstructed kidney. When these substances were injected into the renal pelvis and the ureter ligated, higher levels were detected in lymph than in blood. However with neither substance did the amount in lymph exceed a fraction of 1% of the total injected.It is concluded that the increase in lymph flow is attributable to haemodynamic changes involving a redistribution of blood flow within the kidney, and that reabsorption from urine in the renal pelvis is minimal.
RENAL EXCRETION OF POTASSIUM AND POTASSIUM TOLERANCE IN THE PIG
Authors: Mason G. D. , Scott D. 
Published: December 2014

Young pigs given supplements of KCl in the food excreted the additional KCl in the urine indicating the importance of the kidney in the regulation of potassium excretion.Intravenous infusion of KCl increased the concentration of potassium in the plasma and the rate of excretion of potassium in the urine. This increase was proportional to infusion rate and in some experiments the amount of potassium excreted in the urine exceeded the amount filtered at the glomerulus, demonstrating net secretion of potassium by the renal tubule. Urinary excretion of sodium was markedly increased during KCl infusion.After pigs had been given a diet containing supplementary KCl for 6 days their ability to excrete potassium in the urine in response to intravenous KCl infusion was not altered although the sodium diuresis was much reduced.Intravenous infusion of KCl into acidotic pigs resulted in a rise in the rate of excretion of potassium in the urine of less than half that seen in pigs in normal acid‐base balance given the same rate of infusion. Glomerular filtration rate and the amounts of potassium filtered at the glomerulus during KOl infusion were unaffected by acidosis, which suggests that the lowered excretion of potassium in urine seen in acidotic pigs was the result of reduced tubular secretion.
OBSERVATIONS ON A VOLUNTARY TREMOR—VIOLINIST'S VIBRATO
Authors: Schlapp Mary 
Published: December 2014

Observations have been made on a voluntary, rhythmically repeated oscillatory hand movement used by violin players (vibrato). It involves almost isometric contractions of various muscles controlling the movement of the left hand and fingers with flexor‐extensor alternation clearly shown in electromyogram (EMG) records. The movement has a dominant frequency of oscillation (Vn) characteristic for each individual studied. Training improves voluntary control of vibrato rate, those with less technical training showing more loss of smooth alternation when they attempt to slow the rate from their Vn. The rate is not affected by loading the hand and/or arm, nor by abolishing sensation in the finger used for vibrato, but may be slightly quickened by increased (flexor) muscle contraction. With imposed oscillations of different frequencies there was evidence of resonance at Vn rate only when the forearm muscles were contracted, but the few persisting waves of movement seen after cessation of the input oscillation were slower than the input unless this was very close to vibrato frequency. After a vibrato run was stopped persistence of rhythmic EMG groups was seen in flexor, extensor, and dorsal interosseous muscles (but not in pronator teres) with longer persistence in more strongly contracted muscle. These persistent groups accelerated immediately vibrato stopped to a rate within the range of 8–12/sec usually quoted for physiological tremor. Similar persistent groups followed Merton's silent period after nerve stimulation provided there was some initial muscular contraction present. EMG activity at the end of this period seemed to trigger the further cycles which in one playing subject were at Vn frequency. Simultaneous records from forearm flexors and extensors showed alternation of persisting EMG groups following both vibrato and nerve stimulation. The dominance of an individual's Vn frequency and the acceleration from this rate shown by the persisting EMG groups suggests the involvement of more complicated neural pathways than solely that of the myotatic reflex.There are strong similarities between the voluntary movement of vibrato and the involuntary one of physiological tremor, but Vn is always slower than tremor.
THE INFLUENCE OF PARATHYROID HORMONE ON THE SECRETION OF PHOSPHATE BY THE PAROTID SALIVARY GLAND OF SHEEP
Authors: Tomas F. M. 
Published: December 2014

The effect of parathyroid hormone on phosphate secretion by the parotid salivary gland in sheep has been examined in three separate studies: the first, with 3 sheep, used free‐flow salivary collection under anaesthesia and intravenous infusion of hormone; the second involved 4 sheep in which ‘stop‐flow’ techniques were applied to one parotid gland; the third was carried out using 6 sheep in which the blood vessels to one parotid gland were isolated and hormone infused at graded rates directly into the arterial supply to the gland.Parathyroid hormone infusion caused an increase in parotid salivary phosphate concentration and secretion rate in all experiments. The response was rapid (within 2–4 min) and also declined rapidly following cessation of infusion. During hormone administration the ratio of salivary to plasma phosphate concentrations for stopped‐flow samples was significantly higher than for controls (22·0 ± 2·1 (S.E.M.) vs 16·0 ± 2·2). Hormone infusion into the blood supply of the isolated parotid gland at rates estimated to give rise to plasma parathyroid hormone levels of about 5, 10 or 20 ng/ml. caused salivary phosphate concentration to rise by 11·6, 19·6 and 25·7 m‐mole/litre respectively. The increment, whether expressed as a percentage or on an absolute basis, was directly related to the dose rate.Parathyroid hormone infusion also altered the secretion of sodium, potassium and bicarbonate, but not of calcium or magnesium. These changes, and those of phosphate, are discussed in relation to the mode of action of parathyroid hormone.
THE EFFECTS OF BREATHING PATTERN IN THE ESTIMATION OF PULMONARY DIFFUSING CAPACITY
Authors: Kindig Neal B. , Hazlett David R. 
Published: December 2014

The diffusing capacity of the homogeneous lung for carbon monoxide differs when measured by the steady state and single breath methods. Jones and Meade [1961] showed that measured single breath DLCOSB is too large by about 20% if time delays caused by breathing pattern effects are ignored. Here it is shown that measured DCLOSS using the Bohr method is too small by as much as 25% because of similar breathing pattern effects. Steady state and single breath experiments on normal subjects produce close agreement between adjusted values, suggesting that the homogeneous lung at rest is characterized by the same ‘actual’ DLCO parameter in both methods.The adjustment to DLCOSS depends on two important features of the periodic breathing pattern: (1) an ‘effective’ breath‐holding time and (2) the diffusing capacity per unit volume averaged over a cycle. These correspond to T and k of the single breath method.The theoretical conclusions are based on steady state analysis of a homogeneous lung model. The dead space has fixed volume and plug flow. A lumped diffusion parameter DLCO characterizes the alveolar compartment. Alveolar CO concentration and volume are time dependent. Breathing patterns which were modelled were the square‐wave (the periodic equivalent of the single breath method), the ramp and the ramp with a pause at the end of expiration. The latter closely approximates spontaneous breathing patterns which were measured.
CHANGES IN THE METABOLISM OF THE SHIVERING HIND LEG OF THE YOUNG OX DURING SEVERAL DAYS OF CONTINUOUS COLD EXPOSURE
Authors: Bell A. W. , Clarke P. L. , Thompson G. E. 
Published: December 2014

The effect of 4 days of continuous exposure to a cold environment on blood flow in, and oxygen and energy substrate uptake by the shivering hind leg has been studied in young steers. The animals shivered throughout the period of cold exposure and total oxygen consumption (total Vo2) remained 40—50% greater than Vo2 during thermoneutrality. Leg blood flow (leg Q) and oxygen uptake (leg VO2) increased two‐ and four‐fold respectively on the first day of cold. Both had declined significantly by the final day, leg Q to a level 37% greater than, and leg VO2, to about double, pre‐cold levels. The change in the relationships of leg Q and leg Vo2 to total Vo2 was examined by linear regression analysis, which suggested that the changing contribution of leg VO2 to total Vo2 was entirely due to changes in leg Q, rather than in the arteriovenous difference in blood oxyhaemoglobin saturation across the leg. The net uptakes by the leg of free fatty acids (FFA), acetate, glucose and lactate all increased on the first day of cold. Both glucose and acetate uptakes were greater on day 4 than on day 1 in the cold, in spite of the lower leg Vo2, but net uptakes of FFA and lactate were considerably lower. The decrease in net uptake of FFA is attributed mainly to an increase in the rate of lipolysis and release of FFA from fat depots in the leg, because of the associated progressive increase in the release of glycerol and oleic acid from the leg. The molar ratios of net carbohydrate substrate, acetate and FFA uptakes to leg Vo2 are compared.The results suggest that tissues other than the leg muscles become increasingly important as sites of heat production, and that there are changes in the utilization of glucose, acetate and FFA by shivering muscle, during prolonged cold exposure.
THE EFFECT OF PLASMA POTASSIUM IN DETERMINING NORMAL RATES OF EXCRETION OF POTASSIUM IN DOGS
Authors: Baylis Christine , O'Connor W. J. 
Published: December 2014

Doses of 5—15 mmol KCl or KHCO3 (less than the daily intake in food) given by stomach tube or intravenous infusion, produced increases in plasma K and in K excretion, the time delay between change in plasma K and rate of excretion being minimal.Without doses of K salts in control experiments, plasma K concentration was about 4 mmol/l and K excretion about 5 µmol/min. After doses of KCl or KHCO3, plasma K and rate of excretion of K both increased, increase of 0·5 mmol/l in plasma K being associated with an increase of about 35 µmol/min in K excretion.Increased excretion of K was accompanied by a small increase in Na excretion. Excretion of both Cl and HCO3 increased, Cl more after KCl, and HCO3 more after KHCO3.The results indicate that within normal ranges, plasma K is an important factor determining the rate of excretion of K.
THE INFLUENCE OF PARATHYROIDECTOMY UPON CALCIUM AND PHOSPHATE HOMEOSTASIS IN ADULT SHEEP
Authors: McIntosh G. H. , Tomas F. M. 
Published: December 2014

The absorption and secretion of Ca and PO4 were measured with the use of radioactive isotopes in 4 adult sheep before and after parathyroidectomy. Secretion of Ca and PO4 into the stomach and intestines was measured separately.Parathyroidectomy resulted in a negative balance for Ca and PO4 and an accompanying fall in plasma Ca and PO4 concentrations. In the case of PO4 this response was attributed primarily to a reduced intestinal absorption, but for Ca increases in urinary exretion and intestinal secretion also contributed significantly. Secretion of PO4 to the stomach was reduced but endogenous PO4 excretion in the faeces was unchanged which indicated a reduced reabsorption of secreted PO4 by the intestines.
THE EFFECTS OF TWO ANALOGUES OF ARGININE‐VASOPRESSIN (ORNITHINE‐VASOPRESSIN AND DESAMINO‐D‐ARGININE‐VASOPRESSIN) ON KIDNEY FUNCTION IN SHEEP
Authors: Yesberg Nancy E. , Henderson Myrna , Budtz‐Olsen O. E. 
Published: December 2014

The effects of intravenous infusion of ornithine‐vasopressin (OVP) and desamino‐D‐arginine‐vasopressin (dDAVP) were studied in normal and hydrated Merino sheep. In normal sheep, OVP resulted in a diuresis, increased urinary sodium and potassium excretion, and a fall in the plasma potassium concentration. Renal plasma flow remained constant but glomerular filtration rate and filtration fraction rose markedly. dDAVP in normal sheep was antidiuretic, but its only significant effect was a small decrease in plasma osmolality. In the hydrated sheep OVP was antidiuretic and resulted in increased urinary excretion of sodium and potassium, and a fall in the plasma potassium level. Renal plasma flow fell, but glomerular filtration and filtration fraction tended to rise. dDAVP in the hydrated sheep was also antidiuretic but urinary sodium and potassium excretion was reduced. Renal plasma flow and glomerular filtration fell, with a small decrease in filtration fraction.These results suggest that the diuretic effect in normal sheep and the electrolyte‐excreting effects in both normal and hydrated sheep of OVP are related to the increase in glomerular filtration, which in turn is dependent on the vasopressor activity of the hormone. The increase in glomerular filtration caused by OVP is due to an increase in the filtration fraction of an unchanged renal plasma flow, which could be brought about by an increase in renal efferent arteriolar tone.The effects of hydration of the sheep were the conventional increased urine flow, decreased urine osmolality and decreased solute‐free water reabsorption. Sodium and potassium excretion rose slightly and plasma osmolality fell. Renal plasma flow and glomerular filtration both increased with little change in filtration fraction. These effects could be brought about by suppression of endogenous vasopressin and a decrease in both afferent and efferent renal arteriolar tone.
Obsrvations on the Fine structure of the Testicular Interstitial Cells in the Camel (Camelus Dromedarious)
Authors: Tingari M. D. , Moniem K. A. , Künzel E. 
Published: December 2014

Testicular interstitial cells of the camel are polygonal in shape with abundant smooth endoplasmic reticulum (SER) occurring as a network of tubules. Elements of a welldeveloped Golgi complex are seen in many parts of the cytoplasm. There is a moderate number of mitochondria with predominantly lamellar cristae and dense intramitochondrial granules. Lipid droplets vary in size and number from cell to cell. Lysosomal bodies are commonly encountered in the cytoplasm. Other cytoplasmic constituents include microfilaments, peroxisomes, a few pathches of rough endoplasmic reticulum and occasional glycogen particles.The functional significance of these observations is discussed in relation to comparative observations on other vertebrates as in relation to histochemical findings on camel testis. There is sufficient evidence to indicate that the interstitial cells in the camel testis resemble interstitial cells of other vertebrates.Letdig cells during the non‐breeding season possess abundant lipid droplets, large lysosomal bodies together with narrow cisternae of SER, i.e. features of inactivity. Maximal activity is seen during the rutting season and it is suggested that this activity correlates with the of seminiferous epithelium and accessory sex glands.