bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Parathyroid Hormone on the Uptake and Release of Calcium by Bone in Tissue Culture
Authors: Robertson W. G. , Peacock M. , Atkins D. , Webster L. A. 
Published: August 2015

1. Bovine parathyroid hormone at a concentration of 1 unit/ml caused an immediate transient uptake of calcium from the bathing medium by 5-day-old mouse calvaria in tissue culture.
2. The uptake of calcium by bone was followed by the release of calcium into the medium over the subsequent 3–4 h.
3. The results support the conclusion that the primary action of the hormone on calcium transport in bone is to cause an increase in the intracellular concentration of calcium before producing the characteristic release of calcium from bone.
Subcellular Localization of Folate and Effect of Methotrexate on the Incorporation of Radioactive Folic Acid into Guinea-Pig Liver Folate
Authors: Corrocher R. , Hoffbrand A. V. 
Published: August 2015

1. The subcellular distribution of endogenous folate and of injected [3H]folic acid has been studied in guinea-pig liver.
2. Endogenous folate was found to be concentrated in the mitochondrial and cell-sap fractions.
3. At 1 h after injection, labelled folic acid (pteroylglutamic acid) was concentrated in the microsomes (where it is possibly reduced to tetrahydrofolic acid).
4. At all subsequent times after injection of labelled pteroylglutamic acid (4, 24 and 84 h) radioactivity was concentrated in mitochondria and cell sap and it is, therefore, likely that conjugation of glutamates to form pteroylpolyglutamates occurs in one or both of these subcellular fractions in mammalian cells.
5. Methotrexate-treated animals converted at least some labelled pteroylglutamic acid into non-reduced pteroyl di-, tri- and poly-glutamic acids by 4 h after the injection.
6. Reduction of pteroylglutamic acid is, therefore, not essential for pteroylpolyglutamate formation in liver cells.
7. Methotrexate blocks the reduction of pteroyl di-, tri- and poly-glutamic acids, as well as of pteroylglutamic acid.
Ventilatory Response to Exercise and to Co2 Rebreathing in Normal Subjects
Authors: Rebuck A. S. , Jones N. L. , Campbell E. J. M. 
Published: August 2015

1. Changes in ventilation during progressive exercise were measured in eleven normal subjects. Ventilatory response to carbon dioxide at rest was measured in the same subjects using a rebreathing method.
2. The range of ventilatory response to exercise was 16·6–32·0 litres min−1 (litres CO2 min−1)−1 (mean 22·7; SD 5·35); response to O2 uptake was 17·0–43·9 litres min−1 (litres O2 min−1)−1 (mean 29·02; SD 9·07). Ventilatory response to CO2 (Sco2) ranged from 0·81 to 3·22 litre min−1 mmHg−1 (mean 1·87; SD 0·62).
3. There was a highly significant (P &lt; 0·001) correlation between the changes in response to increasing CO2 output or O2 uptake, and Sco2.
4. The results are compatible with the suggestion that ventilation during exercise in normal subjects is directly related to their chemosensitivity to CO2, those having the highest sensitivity showing the greatest exercise ventilation.
Bronchial Sympathetic Activity in Chronic Bronchitis
Authors: Astin T. W. 
Published: August 2015

1. Measurements of airways resistance and lung volume were made in sixteen patients with chronic bronchitis and ten patients without chest disease before and after intravenous propranolol administration.
2. The airways resistance of the patients with chronic bronchitis increased significantly after propranolol administration but in the control subjects there was no significant increase.
3. In the patients with chronic bronchitis the increases in airways resistance were greater when the initial values were high.
4. In seven of the patients with chronic bronchitis and seven further control subjects airways resistance was measured before and after intravenous thymoxamine administration.
5. The airways resistance of the normal subjects was unchanged by thymoxamine administration, but that of the patients with chronic bronchitis decreased significantly.
6. The results are consistent with the existence of bronchial alpha receptors in man. In patients with chronic bronchitis there are greater degrees of both alpha and beta bronchial sympathetic activity than in normal subjects. The greater the severity of the condition the greater is the degree of beta sympathetic activity. In considering the factors causing airways obstruction in chronic bronchitis sympathetic activity should be taken into account.
A Study of Water and Electrolyte Transport by the Excluded Human Colon
Authors: Bown R. L. , Sladen G. E. , Rousseau B. , Gibson J. A. , Clark M. L. , Dawson A. M. 
Published: August 2015

1. Four subjects with colonic exclusion for chronic hepatic encephalopathy were investigated by a perfusion technique in a study of water and electrolyte transport by the colon.
2. The mean values for water and electrolyte transport, mucosal potential difference and colonic volume compare closely with values previously obtained in the intact human colon.
3. A reduction in luminal pH did not affect water or sodium absorption, in contrast with previous animal studies, but did increase chloride absorption, probably on the basis of increased chloride-bicarbonate exchange.
4. Potassium secretion increased with a reduction in luminal pH, possibly as a result of the low pH increasing mucosal permeability.
5. It is concluded that the excluded colon in these patients provides a valid model for studies of normal colonic physiology.
Plasma Volume, Extracellular Fluid Volume and Exchangeable Sodium Concentrations in the New Zealand Strain of Genetically Hypertensive Rat
Authors: Gresson C. R. , Bird D. L. , Simpson F. O. 
Published: August 2015

1. Rats of the New Zealand strain with genetic hypertension (GH rats) were found to have lower plasma volume in relation to body weight than rats of the normotensive parent strain (N rats). GH rats had higher venous packed-cell volume percentage than N rats, but total erythrocyte volume was similar in the two strains of rats. Extracellular fluid volume and exchangeable sodium concentrations were lower in the GH rats. Plasma sodium concentration was not altered; plasma potassium concentration was slightly higher in the GH rats.
2. These results indicate that hypersecretion of a sodium-retaining hormone is unlikely to be a primary factor causing hypertension in the GH rats. Cardiac output has not been measured: if an increased cardiac output is a factor in the maintenance of the hypertension, it is evidently not secondary to an increased blood volume.
3. The lower exchangeable sodium concentrations and body fluid volumes found in the GH rats may be due to lower aldosterone activity secondary to a decrease in the activity of the renin-angiotensin system, or to the effects of the elevated blood pressure on the renal handling of sodium, or to both factors.
Chloride Titration in the Dog: The Influence of Extracellular Fluid Expansion on the Pattern of Chloride Reabsorption
Authors: Cohen J. J. , Bar-Khayim Y. , Garella S. , Chazan J. A. 
Published: August 2015

1. The technique of chloride titration was employed in twenty dogs to determine the pattern of renal chloride handling in response to systematic increases in filtered chloride load. The influence of variations in sodium reabsorption on this pattern was also assessed by producing a wide spectrum of volume expansion during the titration protocols.
2. The results indicate that chloride reabsorption is proportional both to the rate of chloride filtration and to the rate of sodium reabsorption and, hence, that the specific pattern of each chloride titration curve is the fortuitous consequence of the interplay between these two factors.
3. The rate of chloride reabsorption relative to the simultaneous rate of sodium reabsorption was used as an index of the ability of the kidney to maintain chloride homeostasis and indicated that the kidney invariably tends to return depressed. plasma chloride concentration towards normal but, under the conditions of these acute experiments, consistently tends to reduce elevated plasma chloride concentration only when cation reabsorption is markedly depressed.
4. The present observations do not elucidate the mechanism responsible for these findings but suggest that plasma chloride concentration is not regulated through the operation of a threshold mechanism.
Plasma Catecholamine and Dopamine β-Hydroxylase Amounts in Phaeochromocytoma
Authors: Geffen L. B. , Rush R. A. , Louis W. J. , Doyle A. E. 
Published: August 2015

1. Plasma catecholamine and dopamine β-hydroxylase (DβH) amounts were measured in a series of patients with proven phaeochromocytoma and compared with those of a group with essential hypertension.
2. Circulating catecholamine amounts were greatly elevated in phaeochromocytoma but plasma DβH was not significantly raised.
3. There was a significant correlation between plasma noradrenaline and DβH in individuals with essential hypertension but not with phaeochromocytoma.
4. The relative deficiency of DβH secretion in phaeochromocytoma indicates that the mechanism of release of catecholamines from these tumours does not involve the normal exocytosis of catecholamine storage vesicles. This supports the hypothesis that the primary defect responsible for the hypertension is excessive synthesis of catecholamines that bypass the normal storage and secretion mechanisms and diffuse into the circulation.
Polymeric Collagen of Skin in Normal Subjects and in Patients with Inherited Connective Tissue Disorders
Authors: Francis M. J. O. , Smith R. , Macmillan D. C. 
Published: August 2015

1. The major collagen fraction of skin, which in vivo consists of tropocollagen molecules aggregated into extracellular fibres, has been extracted from forty-nine normal subjects and nineteen patients with inherited and acquired disorders of connective tissue.
2. In normal subjects the chemical stability of this fraction progressively increased up to the age of 60.
3. This fraction was less stable than normal in patients with homocystinuria, Werner's syndrome, myositis ossificans progressiva, pseudoxanthoma elasticum, juvenile osteoporosis and acromegaly.
4. In osteogenesis imperfecta (OI) the stability of this fraction was normal in those patients with markedly blue sclerae, although the amount which could be extracted from the skin was low: opposite results were found in those OI patients with sclerae of normal colour.
5. This study provides preliminary evidence of collagen abnormality in several heritable disorders of connective tissue.
Conversion of Angiotensin I into Angiotensin II in the Isolated Perfused Rat Kidney
Authors: Hofbauer K. G. , Zschiedrich H. , Rauh W. , Gross F. 
Published: August 2015

1. In the isolated rat kidney, perfused at constant pressure with a medium free from renin substrate, addition of angiotensin I to the perfusate decreases renal ‘plasma’ flow.
2. A peptide inhibitor, SQ 20881, of converting enzyme reduces the vasoconstrictor effect of angiotensin I up to a maximum of 87%, the degree of inhibition being dose-dependent.
3. The molar, ratio of equi-effective doses of angiotensin I and angiotensin II was 50:1, indicating a low rate of intrarenal conversion of the decapeptide.
4. The vasoconstrictor effect elicited by the addition of renin substrate to the perfusate was not inhibited by SQ 20881, even if the concentration was fifteen times that which produced the maximum inhibition of conversion of angiotensin I.
Forearm Blood Flow during and after Isometric Hand-Grip Contractions
Authors: Mottram R. F. 
Published: August 2015

1. A method is described for the measurement of forearm blood flow during sustained voluntary isometric hand-grip contractions that can be maintained constant by the subject's monitoring of the strength of his contractions.
2. In most subjects it was found that contractions of 5% of their maximal voluntary force could be maintained without fatigue, and without any post-exercise increase in blood flow. More powerful contractions produced both fatigue and a large post-exercise hyperaemia, even though blood flow had reached a plateau during the exercise.
3. An attempt to show that the post-exercise hyperaemia was a response to a steadily accumulating ‘metabolic vasodilator stimulus’ and varied directly in size with the duration of the contraction gave equivocal results.
4. Ischaemic pain in the hand was not the cause of the post-exercise hyperaemia.
Renal Function in Chronic Intravascular Haemolysis Associated with Prosthetic Cardiac Valves
Authors: Slater S. D. , Rahman M. , Lindsay R. M. 
Published: August 2015

1. Glomerular nitration, wate rconcentration and acid load tests, measurement of urinary protein and cell excretion rates, bacteriological examination of the urine, and analysis of the urinary amino acid content were carried out in eight patients with chronic intravascular haemolysis due to aortic valve replacement.
2. All results were normal except for a slight reduction in creatinine clearance rate in two patients and a slight elevation of urinary protein in a third; these abnormalities were considered of doubtful significance.
3. It is concluded that chronic intravascular haemolysis with its consequent renal haemosiderosis appears not to interfere with renal function.
The Effect of Local Anaesthesia of the Airway on Respiratory Reflexes in the Rabbit
Authors: Jain S. K. , Trenchard Diana , Reynolds Felicity , Noble M. I. M. , Guz A. 
Published: August 2015

1. The effect of breathing anaesthetic aerosols (lignocaine 20% and bupivacaine 5%) on respiratory reflexes was studied in rabbits.
2. The cough reflex was blocked in every experiment.
3. The inflation reflex was abolished in eleven out of twenty-six rabbits given lignocaine aerosol and in fourteen out of fifteen rabbits given bupivacaine aerosol.
4. The deflation reflex was blocked pari passu with the inflation reflex.
5. The ventilatory response to histamine was sometimes blocked; more commonly it was partially preserved.
6. The ventilatory response to phenyldiguanide was never impaired and often enhanced.
7. Bronchoconstriction produced by electrical stimulation of the peripheral cut ends of the cervical vagus nerves was unaffected.
8. Block of the above respiratory reflexes was associated with slower, deeper breathing.
9. Bupivacaine has produced more consistent and reliable results than lignocaine; the effects were reversible in both cases usually within 30 min.
10. Plasma concentrations of both anaesthetics were usually below the generally accepted toxic concentrations in man.
11. Control experiments using intravenous infusions of the anaesthetics proved that none of the effects could have been produced by systemic effects of the absorbed anaesthetic.
12. No pathological changes were found in the airways on both macroscopic and microscopic examination.
13. The experiments show that it is possible to block respiratory reflexes whose afferents arise from the airways, and to preserve a reflex arising at alveolar level.
Iron-Deficiency Anaemia: Its Effect on Maximum Aerobic Power and Responses to Exercise in African Males Aged 17–40 Years
Authors: Davies C. T. M. , Chukweumeka A. C. , Van Haaren J. P. M. 
Published: August 2015

1. The physiological responses to exercise of two groups of industrial workers with moderate and severe anaemia were measured and compared with a group of matched controls, working and living under similar conditions. Exercise was performed on a stationary bicycle ergometer at five consecutive work loads. During the final minute of each exercise periods, oxygen intake, minute ventilation volume, and cardiac and respiratory frequencies were measured. On a separate occasion, blood haemoglobin concentration was measured at rest and cardiac output and blood and plasma volumes were estimated while subjects exercised at a fixed percentage of the maximum aerobic power for 6 min.
2. Oxygen intake for a given work load and ventilation rate was similar in all subjects studied but exercise cardiac output was elevated in the anaemic group. The increased cardiac output was due to an increased heart rate, the stroke volume being similar in the anaemic and control subjects. There was a marked decrement (∼34%) in maximum aerobic power and some evidence of a raised plasma volume in the severely anaemic group.
3. These results suggest that anaemia impairs performance during moderate and near maximum exercise. There is an associated rise of cardiac output and plasma volume.
Sites of Maximal Absorption and Hydrolysis of Two Dipeptides by Rat Small Intestine in Vivo
Authors: Crampton R. F. , Lis Maria T. , Matthews D. M. 
Published: August 2015

1. Though mucosal uptake of peptides plays an important part in protein absorption, little is known about the site of maximal absorption of peptides in the small intestine. This paper reports an investigation of the characteristics of absorption and hydrolysis of l-methionyl-l-methionine (Met-Met) and glycylglycine (Gly-Gly) by tied loops along the length of the small intestine of the rat, and those of absorption of the equivalent l-methionine (Met) and glycine (Gly).
2. Absorption of Met-Met, or a mixture of Met-Met and Met, was maximal in the proximal half of the small intestine, whereas absorption of Met was maximal in the distal half. Absorption of Met-Met was greater than that of the equivalent Met, especially in the proximal small intestine. In most sites, absorption of a mixture of Met-Met and Met was not significantly different from that of the equivalent Met-Met. Absorption of Met was not increased by raising its concentration from 100 to 200 μmol/ml, but addition of Met-Met (50 μmol/ml) produced a large increase in absorption, indicating that absorption of Met from Met-Met is independent of that from free Met. During absorption of Met-Met, large amounts of free Met appeared in the intestinal lumen. Most of this resulted from intralumen hydrolysis. The hydrolytic ability of mucosal homogenates was several times greater than that required to hydrolyse the Met-Met disappearing from the lumen during absorption.
3. The sites of maximal absorption of Gly-Gly, Gly and a mixture of Gly-Gly and Gly, were all in the proximal half of the intestine near the mid-point. Absorption of Gly-Gly was greater than that of the equivalent Gly, especially in the proximal sites. In several sites, there was no significant difference between absorption of a mixture of Gly-Gly and Gly and that of the equivalent Gly-Gly. During absorption of Gly-Gly, the amounts of free Gly appearing in the lumen were small except in the two most distal sites. Most of the free Gly resulted from back-diffusion from the mucosa. The hydrolytic ability of mucosal homogenates was barely adequate to hydrolyse the Gly-Gly disappearing from the lumen during absorption.
4. The results suggest that there is no real discrepancy between the site of maximal absorption of protein digestion products from tied loops of small intestine and that of their absorption in the intact animal. They indicate that absorption of Met and Met-Met involves independent mechanisms, and confirm previous evidence that the capacity of the intestine to absorb mixtures of peptides and amino acids is greater than its capacity to absorb amino acids alone.
Protective Effect of Frusemide in Acute Tubular Necrosis and Acute Renal Failure
Authors: Bailey R. R. , Natale R. , Turnbull D. I. , Linton A. L. 
Published: August 2015

1. Acute tubular necrosis (ATN) with acute renal failure (ARF) was induced in rats with (a) a combination of subcutaneous (s.c.) cephaloridine 500 mg/kg, frusemide 50 mg/kg and 4 ml/kg of 50% (v/v) glycerol in sterile water, (b) s.c. cephaloridine 1500 mg/kg, (c) s.c. mercuric chloride 2·0 and 4·7 mg/kg and (d) both s.c. and intramuscular glycerol (10 ml/kg in sterile water).
2. Pretreatment of rats with varying doses of frusemide protected against both the ATN and ARF of all the models except for glycerol where the ATN and ARF was aggravated. The protection against the ATN of cephaloridine alone and the ATN and ARF of the cephaloridine-glycerol-frusemide combination was almost complete if the last (or only) frusemide pretreatment injection was given 5–12 h before the challenge. Frusemide administered together with cephaloridine makes the ATN and ARF more severe.
3. The pretreatment regime results in moderate dehydration, a lowered serum potassium, a markedly elevated plasma renin activity and a reduced glomerular filtration rate. All these factors would be expected to increase the damage resulting from the nephrotoxic challenges, rather than to protect against it.
4. The possible mechanism of this protection conferred by frusemide pretreatment on the ‘toxic’ type of ARF is discussed. With this type of nephrotoxic insult the resulting ATN involves mainly the proximal convoluted tubules. The potentiation of the ‘circulatory’ type of ARF by frusemide pretreatment probably results from the effects of dehydration.
The Ventilatory Response to Hypoxia during Exercise in Cyanotic Congenital Heart Disease
Authors: Taylor M. R. H. 
Published: August 2015

1. In contrast to the diminished ventilatory response to hypoxia which has been found at rest in cyanotic congenital heart disease, hyperventilation was noted on exercise in children who were cyanosed.
2. Sixteen children had low arterial oxygen saturations on exercise and thirteen of these hyperventilated by an amount similar to that reported in normal adults breathing hypoxic gas mixtures.
3. The three children who had little ventilatory response in relation to the increase of hypoxia during exercise all had a triad of long-standing cyanosis starting early in life, high haemoglobin concentration and low arterial oxygen saturation at rest in air.
Oxygen Consumption in Children with Congenital Diseases of the Heart
Authors: Kappagoda C. T. , Greenwood P. , Macartney F. J. , Linden R. J. 
Published: August 2015

1. An open-circuit method for the measurement of oxygen consumption in children which is suitable for use during cardiac catheterization has been described.
2. Since it has been previously shown that there is no systematic error in this method, the accuracy of the method is described by the random error (i.e. reproducibility). The reproducibility of the method has been determined by the repeated measurement of oxygen consumption in children with congenital diseases of the heart under specified ‘standard’ conditions.
3. A simple method of predicting the oxygen consumption in these children was devised by subjecting the data to a multivariate regression analysis.
4. It is concluded that the accuracy of these predictions, although considerably better than that in the published literature, is not good enough to merit its use in the routine haemodynamic assessment.
Studies on Hypertension in Spontaneously Hypertensive Rats
Authors: Okamoto Kozo , Yamori Yukio , Nosaka Shoichiro , Ooshima Akira , Hazama Fumitada 
Published: August 2015

1. The pathogenesis and complications occurring in spontaneously hypertensive rats (SHR) have been studied.
2. Genetic factors are important both in the development of hypertension and in determining susceptibility to vascular lesions.
3. Selective substrains of SHR may be particularly prone to develop cerebrovascular lesions.
Effect of Low-Density Lipoprotein Preparations on Plasmin
Authors: Herbert Robyn J. , Bennett B. , Ogston D. 
Published: August 2015

1. Crude preparations of β-lipoprotein inhibited the fibrinolytic and caseinolytic activity of plasmin: they were contaminated by α2-macroglobulin and α1-antitrypsin, known inhibitors of plasmin.
2. Purified β-lipoprotein, free from α2-macroglobulin and α1-antitrypsin, did not inhibit plasmin. It is concluded that β-lipoprotein does not have antiplasmin properties.