bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Evaluation of Rebreathing Methods for Measuring Mixed Venous P
co2 During Exercise
Authors: Godfrey S. , Wolf Eliana 
Published: August 2015

1. Measurements have been made of mixed venous Pco2 (PV̄co2) by two methods during exercise at 50 and 100 W in five adult male subjects.
2. The equilibration (plateau) method and the extrapolation (Defares) method were performed alternately, five times each, during the steady-state exercise.
3. The coefficient of variation of PV̄,co2 by the extrapolation method was much higher than that of the plateau method. The PV̄,co2 can be estimated to within ± 1 mmHg by the plateau method, and the derived cardiac output to within ± 0·5 1/min in most cases. The cardiac output calculated by this method agrees closely with that found by direct methods in other studies, whereas the extrapolation method usually overestimates the cardiac output in adults.
4. It is suggested that the degree of variation in the extrapolation method is due to technical factors in construction of the line and to the difficulty of deciding what constitutes the end-tidal Pco2.
An Intrinsic Rhythm of Urinary Calcium Excretion and the Specific Effect of Bedrest on the Excretory Pattern
Authors: Ede M. C. Moore , Faulkner M. H. , Tredre Barbara E. 
Published: August 2015

1. The diurnal rhythms of urinary calcium excretion were studied in healthy subjects under four different regimens in which diet, activity and posture were varied. The excretory rhythms observed were compared with those of potassium, obtained under the same conditions.
2. When the subjects were active throughout the day and night and were either fasting or eating standard three-hourly meals, an intrinsic calcium rhythm was isolated with maximum amounts excreted between 06.00 and 09.00 hours.
3. Continuous supine bedrest was found to have a specific effect on calcium excretion. The total 24 h excretion was markedly increased compared with that found on constant activity but on the same dietary regimen, and 78% of the increase occurred between 09.00 and 18.00 hours.
Distribution of Renal Blood Flow in Patients with Heart Disease
Authors: Fluck D. C. , Evans T. R. , Siggers D. C. , Crawley J. , Srivongse S. A. 
Published: August 2015

1. The renal blood flow distribution has been studied by the Xe washout method in nineteen patients undergoing routine left-sided cardiac catheterization.
2. It was found that there were two separate groups, one in which the washout curve could be analysed by curve stripping into four exponentials, and one in which only three could be detected.
3. The mean cardiac output was found to be lower in the three-component group, whereas the mean glomerular filtration rate did not differ significantly between the two groups.
4. In the four-component group but not in the three-component group, significant linear correlations were detected between cardiac output and glomerular filtration rate, and between glomerular filtration rate and intrarenal blood flow distribution.
5. One suggestion was that the three component distribution of renal blood flow was associated with increasing renal autoregulation and the maintenance of renal function in the presence of a low cardiac output.
6. A second suggestion was that the differences between the three- and four-component group were primarily due to the more intensive diuretic therapy given to the patients in the three-component group.
Relationship between Haemodynamic and Respiratory Function in Patients with Myocardial Infarction and Left Ventricular Failure
Authors: Tattersfield Anne E. , McNicol M. W. , Sillett R. W. 
Published: August 2015

1. Forty-five patients with myocardial infarction and clinical signs of left ventricular failure have been studied with measurements of pulmonary and brachial artery pressure, cardiac output, arterial blood gas pressures and expired air collections.
2. Pulmonary artery pressure was elevated and stroke index was reduced in the majority of patients (89% and 85% respectively). There was a close inverse correlation between these two measurements, both of which appear to be direct consequences of impaired left ventricular function.
3. Arterial hypoxaemia was common and only transiently relieved by hyperventilation. Dead space/tidal volume ratio and venous admixture were both increased, compatible with considerable ventilation/perfusion mismatching in the lung. Both measurements correlated directly with pulmonary artery pressure.
The Effect of Glucocorticoid Withdrawal on Body Water and Electrolytes in Hypopituitary Patients with Adrenocortical Insufficiency as Investigated with 77Br, 43K, 24Na and 3H2O
Authors: Skrabal F. , Arnot R. N. , Joplin G. F. , Fraser T. R. 
Published: August 2015

1. Simultaneous measurements of exchangeable Na+, exchangeable K+, extracellular fluid volume and total body water, with 24Na, 43K, 77Br and 3H2O, were carried out in patients with adrenocortical insufficiency due to pituitary ablation performed 1–3 months previously.
2. The first group of five patients was studied before and after withdrawal of maintenance prednisone (2·5 mg three times daily, orally). The effects of glucocorticoid withdrawal were: (a) an increase in intracellular water (all cases) and a decrease in the extracellular fluid volume (four cases) irrespective of any change in serum Na+ concentration; (b) an increase in residual (‘intracellular’) Na+ in all cases which was matched by a loss of extracellular Na+, so that total body Na+ remained unchanged, and (c) the cortisol deficiency clinical syndrome. Exchangeable K+ remained unchanged.
3. Similar measurements were obtained with two further patients during the corticosteroid withdrawal period, throughout which they were kept on a maintenance dose of deoxycorticosterone acetate, 1·0 mg twice daily sublingually. Neither the above biochemical changes nor the cortisol deficiency syndrome developed.
4. The shift into the cells of water and Na+ may depend on the same defect caused by glucocorticoid deficiency, and may be the cause of the cortisol deficiency syndrome.
The Interrelations of Faecal Ammonia, pH and Bicarbonate: Evidence of Colonic Absorption of Ammonia by Non-Ionic Diffusion
Authors: Down P. F. , Agostini L. , Murison J. , Wrong O. M. 
Published: August 2015

1. Ammonia, bicarbonate and pH were measured in samples of faecal dialysate from thirteen healthy subjects taking free diets. To observe the effect of marked changes in faecal pH, three subjects were also studied while taking 25 mmol/day of MgCO3 or Na2SO4 by mouth. Both salts increased stool weight without causing diarrhoea, but stool pH was significantly increased by MgCO3 and decreased by Na2SO4.
2. The total ammonia concentration and pH of faecal dialysate were very variable, but showed a highly significant negative correlation similar to that already established in man between urinary excretion of ammonia and urine pH. This relationship was more marked when individual subjects were studied while faecal pH was deliberately varied by administration of MgCO3 and Na2SO4.
3. Faecal bicarbonate concentrations were positively correlated with pH. Faecal Pco2 was usually in the range 40–120 mmHg, the higher Pco2 values being found in the more acid samples. Faecal total ammonia concentrations were negatively correlated with faecal bicarbonate.
4. These findings suggest that passive non-ionic diffusion is the main mechanism by which ammonia is absorbed by the colon, but do not exclude a minor contribution from diffusion of ionized ammonium. Colonic secretion of bicarbonate facilitates non-ionic diffusion of ammonia by providing an anion which is also absorbed by non-ionic diffusion, so maintaining an alkaline intraluminal reaction that continues to generate unionized ammonia.
Initial Increase of Plasma Radioactive Calcium after Intravenous Injection of Calcitonin in Man
Authors: Caniggia A. , Gennari C. , Piantelli F. , Vattimo A. 
Published: August 2015

1. An intravenous infusion of calcitonin produced a sudden increase of plasma radioactivity after intravenous administration of 47Ca in man.
2. This effect was noted a few minutes before the well-known decrease of plasma calcium concentration.
3. A mathematical evaluation of this phenomenon demonstrated that: (a) it was significant in normal subjects, provided patients were given calcitonin 60–360 min after the intravenous injection of 47Ca; (b) it was generally not significant in patients with senile osteoporosis or osteomalacia; (c) it was particularly evident in patients with generalized Paget's disease or multiple myeloma.
4. Surface measurements performed on soft tissues and bone demonstrated a transient, simultaneous decrease of 47Ca radioactivity from bone.
5. The increase in plasma radioactivity implies a shift of 47Ca from reservoirs with high specific radioactivity, possibly bone cells, to the circulation.
6. According to these data two different mechanisms of action of calcitonin could be considered: an early effect on bone cells producing a shift of calcium to the circulation, and the well-known later hypocalcaemic effect through diminution of bone resorption.
Cortisol and Aldosterone Excretion and Plasma Cortisol Concentrations in Normal and Obese Female Subjects
Authors: Hankin Margaret E. , Theile Helen M. , Steinbeck A. W. 
Published: August 2015

1. The 24 h urinary excretion of free cortisol and aldosterone-18-glucuronide has been studied in twenty-three control and twenty-three grossly obese subjects by a double-isotope-dilution derivative method.
2. Day-night variation of plasma and urinary cortisol has also been investigated.
3. The mean absolute steroid values were similar for the obese and non-obese subjects.
4. The 24 h urinary values for free cortisol expressed as μg/kg of body weight were significantly higher for the controls.
5. The majority of the obese and control subjects had a day-night variation of plasma cortisol. All subjects, with two exceptions, showed day-night variation of free cortisol in the urine.
6. It is suggested that the estimation of unconjugated cortisol in timed urinary collections could be useful for investigations of adrenocortical function.
7. The findings do not support the presence of increased adrenocortical activity in developed obesity.
Amounts of Faecal Porphyrin-Peptide Conjugates in the Porphyrias
Authors: Moore M. R. , Thompson G. G. , Goldberg A. 
Published: August 2015

1. The levels of ‘X-porphyrin’, a porphyrin-peptide complex, have been studied in the faeces of patients with different types of porphyria, as well as in fifty normal subjects.
2. These levels have been shown to be significantly elevated in untreated porphyria cutanea tarda and in variegate porphyria.
3. Lesser elevations were seen in acute intermittent porphyria and hereditary coproporphyria. There was no elevation in erythropoietic protoporphyria.
Relation of the Extracellular [Bicarbonate]/[Chloride] Ratio to Erythrocyte Sodium Content: A Possible New Control System
Authors: Needle M. A. , Shapiro W. , Viswanathan V. , Semar M. 
Published: August 2015

1. Erythrocytes were incubated in buffers with different [bicarbonate]/[chloride] ratios.
2. The erythrocyte sodium content was higher in buffers with higher [bicarbonate]/ [chloride] ratios.
3. The rise in erythrocyte sodium concentration with increase in [bicarbonate]/[chloride] ratio was independent of the effects of ouabain and ouabain plus ethacrynic acid. Primaquine-induced changes in membrane permeability, ATP depletion by starvation and the use of potassium-free buffers did not change the effect.
4. The results may demonstrate a system which either increases the permeability of erythrocytes to sodium or regulates the sodium content of erythrocytes by a carrier system which is independent of ATP.
Influence of Cortical Plasma Transit-Time on p-Aminohippurate Extraction during Induced Renal Vasodilatation in Anaesthetized Dogs
Authors: Velasquez M. T. , Notargiacomo A. V. , Cohn J. N. 
Published: August 2015

1. The influence of intrarenal blood-flow distribution and plasma transit-time through the renal cortex on the reduction in p-aminohippurate (PAH) extraction (EPAH) induced by renal vasodilator agents was evaluated in anaesthetized dogs by an indicator-dilution technique.
2. Increases in renal blood flow during graded intravenous iso-osmotic saline or hyperosmotic mannitol infusions and during renal arterial infusions of acetylcholine or prostaglandin E1 were consistently associated with reduced EPAH.
3. The cortical fraction of renal blood-flow increased during vasodilatation induced by saline or acetylcholine but was unchanged during mannitol or prostaglandin infusions. Cortical blood volume (CBV) increased with saline infusion but was reduced with mannitol. Changes in CBV with acetylcholine and prostaglandin E1 were insignificant. No correlation could be found between changes in EPAH and changes in intrarenal blood flow distribution.
4. A high degree of correlation (r = 0·81) was noted between EPAH and the simultaneously determined mean cortical plasma transit-time. A significant correlation existed with pooled data for all infusions as well as with individual drug infusions.
5. We interpret these data to indicate that a shortened transit-time of plasma through the cortex, indicative of an increased velocity of cortical plasma flow, is the most important determinant of the lowering of EPAH during renal vasodilatation.
Effect of Catecholamines and other Vasoactive Substances on Superficial Hand Veins in Man
Authors: Collier J. G. , Nachev C. , Robinson B. F. 
Published: August 2015

1. The direct effect of catecholamines and other vasoactive substances on superficial hand veins has been studied in man. Drugs were infused locally into the vein and changes in vein size at a constant congesting-pressure were measured by a simple optical technique.
2. Noradrenaline, adrenaline, 5-hydroxytryptamine and angiotensin II caused venoconstriction. Large doses of angiotensin II resulted in rapid development of tachyphylaxis.
3. Isoprenaline, bradykinin, acetylcholine and histamine had no effect on the relaxed vein but all caused dilatation when infused into veins preconstricted by noradrenaline or 5-hydroxytryptamine.
4. No effect of vasopressin could be demonstrated.
A Comparison of the Fat-Free Mass of Young Adults Estimated by Anthropometry, Body Density and Total Body Potassium Content
Authors: Womersley J. , Boddy K. , King Priscilla C. , Durnin J. V. G. A. 
Published: August 2015

1. The fat-free mass (FFM) of ten male and ten female subjects was calculated from measurement of (i) height and weight, (ii) skinfold thickness, (iii) body density, (iv and v) total body potassium by two different methods. All the subjects were apparently healthy and in the medium range of body build and they were mainly young adults.
2. The mean FFM of the ten male subjects was similar as calculated by all methods, although comparisons between pairs of methods sometimes produced discrepancies of up to 2 kg.
3. Agreement was less good for the females but, with the exception of one of the potassium methods, still reasonable.
4. The potassium content of the FFM as mEq K/kg of FFM, was compared with the direct analysis of Forbes, Gallup & Hursh (1961) on four male cadavers. The agreement was close for the men but the K content of the FFM in women was lower than that for men. This difference is discussed.
The Co2 Titration Curve of Mixed Venous Blood
Authors: Kappagoda C. T. , Stoker J. B. , Snow H. M. , Linden R. J. 
Published: August 2015

1. Simultaneous CO2 titration curves of arterial and mixed venous blood were determined in both dog and man in vivo.
2. The slopes of the CO2 titration curves of mixed venous blood were significantly less than those of the corresponding arterial curves.
3. The non-respiratory pH values of the CO2 titration curves of mixed venous blood were significantly greater than those of the corresponding arterial curves.
4. The theoretical explanations of these differences have been discussed.
Intestinal Dipeptide Transport in Normal and Cystinuric Subjects
Authors: Hellier M. D. , Holdsworth C. D. , Perrett D. , Thirumalai C. 
Published: August 2015

1. The absorption of lysine and two lysine-containing dipeptides was studied in normal and cystinuric subjects by jejunal perfusion. Absorption of each dipeptide was compared with that of its constituent amino acids.
2. in normal subjects lysine was better absorbed from the dipeptide glycyl-l-lysine than from the equivalent amino acid mixture. in cystinuric patients lysine was absorbed very poorly in its free form but was absorbed normally from the dipeptide. in cystinuric patients lysine was also absorbed faster as l-lysyl-l-lysine than as free lysine.
3. During perfusion of both dipeptides significantly greater quantities of free lysine were found within the intestinal lumen in cystinuric subjects than in normal subjects. This is thought to be due to back-diffusion after hydrolysis of dipeptide by the mucosa.
4. These observations confirm the existence of dipeptide transport systems independent of those for free amino acids.
Biochemical Changes in Intestinal Mucosa after Experimental Small Bowel by-Pass in the Rat
Authors: Gleeson M. H. , Dowling R. H. , Peters T. J. 
Published: August 2015

1. After experimental small bowel by-pass the excluded segment of intestine, whether jejunum or ileum, shows a decrease (expressed in units/cm of intestine) in mucosal weight, protein, RNA and activity of all eight enzymes studied (leucyl β-naphthylamidase, alkaline phosphatase, β-galactosidase, α-glucosidase, aryl sulphatase, β-glucuronidase, cytochrome oxidase and catalase). There is a fall in DNA content and there are no consistent changes in enzyme activity when expressed as units/mg of DNA.
2. The intestine remaining in continuity after small bowel by-pass shows an increase (expressed in units/cm of intestine) in mucosal weight, protein, RNA and enzyme activity. There is an accompanying rise in DNA content in the intestine in continuity.
3. The increased values of all variables measured in the intestine in continuity are much more marked in ileum than in jejunum.
4. The adaptive changes seen in the by-passed intestine and the intestine in continuity are a result of ‘hypoplasia’ and ‘hyperplasia’ respectively.
Composition of Pteroylpolyglutamates (Conjugated Folates) in Guinea-Pig Liver and Their Formation from Folic Acid
Authors: Corrocher R. , Bhuyan B. K. , Hoffbrand A. V. 
Published: August 2015

1. The composition of guinea-pig liver folates and the biochemical route of formation of liver folates from injected tritium-labelled pteroylglutamic acid (folic acid) have been studied.
2. Endogenous folate was measured by microbiological assay with Lactobacillus casei and Streptococcus faecalis, with and without deconjugation of whole liver pteroylpolyglutamates (conjugated folates). Individual folate compounds were identified by microbiological assay after fractionation of liver folates by DEAE cellulose ion-exchange column chromatography.
3. Liver folate in the guinea-pig consists of about 84–87% reduced pteroylpolyglutamates with more than three glutamate moieties/molecule, about 12–15% reduced pteroyltriglutamates, about 1% reduced pteroyldiglutamates and only traces of reduced pteroylmonoglutamates.
4. About 53% of the liver folate consists of methylated derivatives.
5. Injected pteroylglutamic acid was first rapidly reduced and formylated or methylated. Glutamate moieties were then added, probably singly, to form di-, tri- and poly-glutamates. This was a relatively slow process with a hold-up at the triglutamate stage.
6. The proportion of the labelled pteroylglutamic acid in the polyglutamate form approximated to the proportion of endogenous folates in this form after 3–4 days.
7. The amount of radioactive folate in the liver increased progressively from 1 to 84 h after injection of a standard amount of radioactive pteroylglutamic acid.
The Action of L(-)-Dopa on Baroreflexes in Parkinsonism
Authors: Reid J. L. , Calne D. B. , George C. F. , Vakil S. D. 
Published: August 2015

1. The intra-arterial blood pressure responses to Valsalva's manoeuvre and postural change were investigated as indices of cardiovascular reflex activity in seventeen Parkinsonian patients on maximally tolerated doses of l(-)-dopa (levodopa) and repeated in nine patients on levodopa with an extracerebral decarboxylase inhibitor, l-alpha methyldopahydrazine. The results were compared with control pretreatment responses.
2. There was significant impairment of the pressor response to Valsalva's manoeuvre on levodopa, which returned to control values after the addition of l-alpha methyldopahydrazine.
3. The systolic, diastolic and mean arterial pressures measured in a horizontal position during treatment with levodopa, with and without l-alpha methyldopahydrazine, were significantly lower than pretreatment values.
4. It is concluded that the impairment of baroreflex function by levodopa is mediated, at least in part, at the periphery. In contrast, mechanisms operating within the central nervous system contribute to the lowering of blood pressure recorded in the horizontal position in patients receiving levodopa.
Synthesis of Human Parathyroid Hormone by Cultured Cells: Evidence for Release of Prohormone by Some Adenomata
Authors: Martin T. J. , Greenberg P. B. , Michelangeli V. 
Published: August 2015

1. Monolayer cultures of human parathyroid cells were established for a study of the nature of secreted human parathyroid hormone (HPTH).
2. [14C]Leucine and 75Se-labelled methionine were used as amino acid precursors for the biosynthesis of HPTH.
3. Immunoreactive labelled HPTH in the medium was extracted by affinity chromatography.
4. In cultures from glands, six adenomatous and one hyperplastic, radioactive HPTH in the media was indistinguishable in size and charge from highly purified bovine parathyroid hormone (PTH).
5. In two cultures from adenomata, media contained an immunoreactive basic peptide resembling ‘pro-PTH’ in its electrophoretic behaviour. The freeze-dried cells contained the same basic peptide.
Iron Metabolism after Renal Transplantation
Authors: Boddy K. , Will G. , Lawson D. H. , King Priscilla C. , Linton A. L. 
Published: August 2015

1. The oral absorption and the rate of loss from the body of radioactive iron were measured by whole-body monitoring in patients with functioning renal homografts. The incorporation of radioactive iron into erythrocytes was also measured.
2. The results were compared with corresponding values in normal subjects and in non-dialysed and dialysed patients with chronic renal failure.
3. The mean oral absorption and incorporation into erythrocytes of radioactive iron was intermediate between that of normal subjects and of both non-dialysed and dialysed patients with chronic renal failure.
4. The mean rate of loss from the body was not significantly different from that in normal subjects and non-dialysed patients with chronic renal failure but it was significantly less than that in dialysed patients.
Changes in Glomerular Filtration Rate during Long-Term Treatment with Propranolol in Patients with Arterial Hypertension
Authors: Ibsen H. , Sederberg-Olsen P. 
Published: August 2015

1. Glomerular filtration rate was determined from 51Cr—EDTA clearance in twenty hypertensive subjects treated with propranolol.
2. A significant mean decrease of 13% in the glomerular filtration rate was found during treatment, and an increase of the same order of magnitude after withdrawal of propranolol.
3. It is suggested that these changes are related to a reduction in the renal blood flow.
4. No significant changes were found in plasma volume.