bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Analysis of Decay Curves
Authors: Lafferty H. H. , Giddings A. E. B. , Mangnall D. 
Published: August 2015

1. The limitations inherent in the conventional treatment of glucose decay curves as first-order rate systems are described.
2. The conventionally derived K value is a rate constant and should not be confused with a rate.
3. First-order systems are described by this rate constant and the initial concentration of substance studied. They cannot be described by either factor alone.
4. Two parallel curves cannot both result from first-order systems.
5. If K is conventionally calculated for two parallel curves, then the value obtained for the upper curve must be smaller than the value for the lower.
Release by Vasopressin of E-Type Prostaglandins from the Rat Kidney
Authors: Bell C. , Mya M. K. K. 
Published: August 2015

1. In order to test whether the release of E-type prostaglandins from the kidney by various vasoconstrictor stimuli is related specifically to adrenoreceptor activation, we have compared release of prostaglandin E-like material from perfused rat kidneys during infusion of noradrenaline or vasopressin.
2. Concentrations of noradrenaline or vasopressin that produced comparable rises in renal perfusion pressure also released comparable amounts of prostaglandin E-like material. This effect was abolished by infusion of an inhibitor of prostaglandin synthesis into the kidney.
3. We conclude that liberation of E-type prostaglandins during renal vasoconstriction is probably related to the activation of intra-renal smooth muscle and does not involve any specific hormonal receptor. Stimulation of release of prostaglandin E may explain certain reported renal actions of vasopressin.
Metabolism of Intravenously Administered Dipeptides in Rats: Effects on Amino Acid Pools, Glucose Concentration and Insulin and Glucagon Secretion
Authors: Adibi S. A. , Krzysik B. A. , Drash A. L. 
Published: August 2015

1. Studies were performed to investigate the metabolic fate of dipeptides when administered intravenously in rats. Glycyl-leucine, glycylglycine or glycylsarcosine was injected into the jugular vein. The plasma disappearance rate after the peak plasma concentrations was most rapid for glycyl-leucine and least rapid for glycylsarcosine.
2. During urine collection for 40 min, trace amounts of glycyl-leucine and glycylglycine and 13% of the injected glycylsarcosine were excreted.
3. Neither glycylglycine nor glycyl-leucine was detected in the liver, muscle, intestinal mucosa or renal cortex, but concentrations of glycine or leucine, or both, in these tissues were increased after each injection. In contrast, glycylsarcosine was recovered in all these tissues with concentrations in the renal cortex being far greater than in any other tissue, but sarcosine was found only in the renal cortex and intestinal mucosa.
4. The changes in plasma concentrations of free amino acids, glucose and glucagon, and tissue concentrations of free amino acids, were similar after the intravenous administration of glycyl-leucine and an equimolar mixture of free glycine and leucine. However, the amount of insulin secreted during the 40 min after glycyl-leucine injection was 1·6 times that produced after the injection of the corresponding amino acid mixture.
5. Results show that, within the present experimental conditions, the intravenous administration of dipeptides is as effective as that of the corresponding free amino acids in enriching the tissue pools of amino acids. It is suggested that efficient hydrolysis by cellular enzymes prohibits accumulation of intact dipeptides in body tissues.
Accentuation of Ethanol-Induced Fatty Liver by Phenobarbitone
Authors: Marsh A. R. , Fraser H. S. , Breckenridge A. , Lewis B. , Thompson G. R. 
Published: August 2015

1. Four groups of rats received a liquid formula diet, given alone (control), or supplemented with either ethanol or phenobarbitone, or both together.
2. The ethanol-treated group showed a fall in plasma triglyceride and a rise in liver triglyceride, as compared with the control rats.
3. The phenobarbitone-treated group showed a marked rise in plasma triglyceride but not in liver triglyceride.
4. The group receiving both ethanol and phenobarbitone also showed a rise in plasma triglyceride, but this was accompanied by a striking increase in liver triglyceride.
5. These results suggest that ethanol and phenobarbitone each stimulate triglyceride synthesis but that in addition ethanol has an inhibitory effect on hepatic triglyceride secretion.
Human Hepatic δ-Aminolaevulinate Synthase: Requirement of an Exogenous System for Succinyl-Coenzyme a Generation to Demonstrate Increased Activity in Cirrhotic and Anticonvulsant-Treated Subjects
Authors: Bonkowsky H. L. , Pomeroy Joanne S. 
Published: August 2015

1. We have studied activity of δ-aminolaevulinate synthase in needle liver biopsy specimens obtained from 12 human cirrhotic subjects, five subjects who had ingested anticonvulsants and from control subjects. Liver iron concentrations and quantitative urinary excretions of porphyrins plus their precursors were also determined.
2. In liver homogenates from subjects of each group, addition of an exogenous system for generation of succinyl-coenzyme A (CoA), including succinic thiokinase, resulted in appreciable enhancement of activity beyond that obtained without this system.
3. Mean activities for δ-aminolaevulinate synthase were not significantly different among patient groups when assayed without the exogenous succinyl-CoA-generating system, but liver homogenates from cirrhotic patients and subjects ingesting anticonvulsants had significantly higher activities than control subjects in the presence of the succinyl-CoA-generating system.
4. Although mean liver iron concentration in the cirrhotic group was slightly higher than in control subjects, and in control subjects there was some correlation between liver iron concentration and activity of δ-aminolaevulinate synthase, variations in this activity could not be accounted for solely on the basis of chronic hepatic deposition. Nor were these variations ascribable to differences among subjects in ingestion of ethanol before biopsy or severity of hepatic inflammation as judged biochemically and histologically.
5. Cirrhotic subjects excreted more uro- and copro-porphyrin than control subjects, whereas subjects ingesting anticonvulsants excreted more δ-aminolaevulinic acid and porphobilinogen than control subjects. However, these increases were small and not sufficient to account for all the increased δ-aminolaevulinic acid which potentially could have been formed by these subjects.
6. These considerations raise the possibilities that, in vivo: (a) rate of human hepatic synthesis of δ-aminolaevulinic acid is modulated by the supply of succinyl-CoA; (b) the rate of hepatic synthesis of haem is increased in cirrhotic patients and subjects ingesting anticonvulsants; (c) other important routes exist for disposition of haem precursors in these subjects, besides utilization for haem synthesis.
Plasma Calcitonin in Chronic Renal Failure: Relation to other Factors of Importance in Bivalent Ion Metabolism
Authors: Shainkin-Kestenbaum R. , Lerman R. , Reuben A. , Berlyne G. M. 
Published: August 2015

1. Plasma concentrations of human calcitonin were measured in groups of patients with chronic renal failure, treated either conservatively or by haemodialysis, and compared with a normal group of persons.
2. Plasma calcitonin was statistically significantly elevated in both groups with renal failure.
3. When the data from the three groups were pooled, plasma calcitonin was found to be inversely correlated with total calcium and directly correlated with plasma creatinine.
Effect of Thyrotoxicosis on the Reflex Hypoxic Respiratory Drive
Authors: Stockley R. A. , Bishop J. M. 
Published: August 2015

1. Oxygen breath tests were performed in seven patients with thyrotoxicosis. The inspired air was replaced by oxygen without their knowledge for 20 s and the fall in ventilation was recorded.
2. Ventilation fell significantly in all the patients within 40 s. The mean fall was 21·1% (se ± 1·7) below the control value.
3. β-Adrenoreceptor blockade with propranolol had little effect on this reduction in ventilation. The fall observed in five patients receiving propranolol was 19·6% (se ± 1·0).
4. After definitive treatment, which rendered the patients euthyroid, the observed reduction in ventilation after breathing oxygen was significantly less at 11·7% (se ± 1·2).
5. It is concluded that patients with thyrotoxicosis have an increased resting reflex hypoxic drive to respiration, when compared with the euthyroid state, and this is unaffected by β-adrenoreceptor blockade.
Respiratory Muscle Fatigue: A Cause of Respiratory Failure?
Authors: Macklem P. T. , Roussos C. S. 
Published: August 2015

1. The question whether respiratory muscle fatigue ever causes respiratory failure is over 40 years old, but we still have no definitive answer to this question. Skeletal muscle fatigue occurs when the rate of energy consumption of themu scle is greater than the energy supplied, so that energy stores are utilized and eventually become depleted.
2. Five factors which are important in the development of muscle fatigue (a, the tension developed by the muscle; b, the maximum tension the muscle can develop; c, the energy stored within the muscle; d, the energy supplied to the muscle; e, the efficiency of the muscle). These can be affected in many diseases, so disposing to fatigue, thus respiratory muscle fatigue is likely to be a common occurrence.
3. Respiratory muscle fatigue can in principle easily be diagnosed at the bedside by application of a simple electromyographic technique used to detect fatigue in other skeletal muscles.
Arrested Bone Growth and Mineral Maturation in Sub-Totally Nephrectomized Rats
Authors: Letteri J. M. , Biltz R. M. , Ellis K. J. , Martino A. , Yasumura S. , Brook D. , Cohn S. H. , Pellegrino E. D. 
Published: August 2015

1. Young, sub-totally nephrectomized rats were used to study the altered mineral metabolism of renal failure and its effects on bone growth and mineral maturation.
2. Rats killed at 4 weeks after sub-total nephrectomy demonstrated less bone growth than the age-matched control animals. These differences diminished in successive 4 week periods and were not significant at 12 weeks after operation.
3. The major differences in bone mineral composition between the uraemic rats and the control rats were: (i) lower CO23;− concentrations, and (ii) higher PO34;− and HPO24;− concentrations.
4. These differences are consistent with the view that bone mineral matures by the conversion of an acidic calcium phosphate precursor into a carbonate-containing apatite, an essential feature of this conversion being the replacement of PO34;− or HPO24;− by CO23;−. By this definition, uraemic rats at 4 weeks after operation contained more immature bone mineral than the control rats. These differences corresponded to the changes in bone weight, and were similarly unaffected at 12 weeks after operation.
5. The effects observed were transient and were reversed as renal function recovered. If renal failure is sustained, however, as in patients with end-stage renal disease, the maturation defect could become a feature of renal bone disease. Specific aetiological factors are discussed, but not identified.
Urine Electrolyte Response to 18-Hydroxy-11-Deoxycorticosterone in Normal Man
Authors: Nicholls M. G. , Fraser R. , Hay G. , Mason P. , Torsney B. 
Published: August 2015

1. To assess whether the adrenal corticosteroid 18-hydroxy-11-deoxycorticosterone [18-(OH)DOC] affects urine electrolyte excretion in normal man, seven male volunteers received 120 μg (353 nmol) intravenously in 1 h. This was compared with glucose (50 g/l; control) and aldosterone (80 μg, 222 nmol) infusions in the same subjects.
2. A definite though weak antinatriuretic response to 18-(OH)DOC was observed, whereas urine potassium excretion was not altered. Aldosterone increased urine potassium excretion and reduced sodium output. Urine pH was lowered by both corticosteroids, aldosterone in general having a more marked effect. Urine volume was not altered by 18-(OH)DOC.
3. Plasma concentrations of 18-(OH)DOC and aldosterone rose approximately tenfold during their respective infusions. Compared with that of aldosterone, the metabolic clearance rate of 18-(OH)DOC was slower and its plasma half-life was longer.
4. We have been able to demonstrate that 18-(OH)DOC has a definite, albeit weak antinatriuretic action in normal man, but whether or not this corticosteroid is capable of elevating the blood pressure in man remains to be shown.
Collagen of Dupuytren's Disease
Authors: Bailey A. J. , Sims T. J. , Gabbiani G. , Bazin S. , Lelous M. 
Published: August 2015

1. In contrast to collagen from the aponeurosis of normal adult subjects, the nodules, contractures and apparently unaffected aponeurosis from patients with Dupuytren's disease contained substantial amounts of type III collagen.
2. The presence of type III collagen supports the previous proposal that the initial response to injury is the synthesis of an increased proportion of this form of collagen. The increased amounts in the apparently unaffected aponeurosis indicate the disease is not strictly focal but more systemic than is usually considered.
The Effect of Adrenaline-Induced Endogenous Lipolysis upon the Mechanical and Metabolic Performance of Ischaemically Perfused Rat Hearts
Authors: Brownsey R. W. , Brunt R. V. 
Published: August 2015

1. The isolated perfused non-working rat heart, subjected to low coronary flow, has been used to study the effects of myocardial ischaemia on both the mechanical and metabolic performance of the heart.
2. In this preparation, adrenaline initially increased developed tension and heart rate, followed shortly thereafter by marked deterioration in mechanical performance to levels below those observed in the control state. These latter responses occurred simultaneously with stimulation of endogenous myocardial lipolysis. The rate of release of non-esterified fatty acids was positively correlated with both the decline in developed tension and the rise in resting tension.
3. The anti-lipolytic agent nicotinic acid had no effect on the initial mechanical responses of the heart to adrenaline but prolonged the period of enhanced tension development after adrenaline and reduced the degree of later deterioration in performance, in addition to blocking lipolytic stimulation.
4. Hearts from rats fed on a diet rich in animal fat contained larger triglyceride reserves and exhibited greater rates of non-catecholamine-stimulated lipolysis than hearts from normally fed rats. During ischaemic perfusion such hearts showed a more marked rise in resting tension and decline in heart rate than hearts from normally fed animals. Such hearts also had an increased incidence of arrhythmias and a slight reduction in developed tension. The initial responses of these hearts from fat-fed rats to adrenaline were also depressed as compared with normal hearts. Hearts from fat-fed rats showed a greater tendency to deteriorate in performance after adrenaline, particularly with falling heart rates and the onset of ventricular fibrillation.
5. We suggest that these results indicate that myocardial lipolysis makes a significant contribution to the adrenaline-induced deterioration in performance seen in these ischaemically perfused rat hearts.
Changes in the Proportions of Plasma Insulin, Proinsulin and a Higher-Molecular-Weight Insulin during Pre- and Post-Operative Glucose-Infusion Tests
Authors: Mangnall D. , Giddings A. E. B. , Lafferty H. H. , Clark R. G. 
Published: August 2015

1. Glucose-infusion tests were performed on patients admitted for elective upper abdominal surgery 1 day before and 1 day after operation. In addition to insulin and proinsulin, a third immunoreactive insulin species of mol. wt. 20 000–30 000 was detected in plasma from two patients. The heterogeneity of plasma immunoreactive insulin (IRI) and the need to consider the effects of all forms, including proinsulin and the high-molecular-weight species, is emphasized.
2. During preoperative glucose infusions there was an increase in the percentage of the total plasma IRI present as high-molecular-weight forms (i.e. proinsulin plus the species of mol. wt. 20 000–30 000) from 3·9% to 10·8%. On the first postoperative morning all patients showed an increase in the amounts of the heavier IRI types, which accounted for 13·9% of the total plasma IRI.
3. The changes in insulin and proinsulin are consistent with the release from the pancreas of an insulin/proinsulin mixture of constant proportions, and the longer circulating half-life of proinsulin.
4. Increases in the amounts of high-molecular-weight IRI species after surgery may have a partial role in the development of insulin resistance but are probably not a major determinant of the insulin-resistant state.
Ventilatory Responses to Exercise and to Carbon Dioxide in Mitral Stenosis before and after Valvulotomy: Causes of Tachypnoea
Authors: Reed J. W. , Ablett M. , Cotes J. E. 
Published: August 2015

1. The ventilation and cardiac frequency during progressive exercise and the respiratory responses to breathing carbon dioxide have been measured in 33 female patients with mitral stenosis and in 31 control subjects. Compared with the control subjects, the patients' exercise ventilation and cardiac frequency were increased; the exercise tidal volume at standard minute volume, the vital capacity and the ventilatory response to carbon dioxide were reduced. The extent to which the standardized tidal volume was lower during exercise than during breathing carbon dioxide was correlated with the severity of the stenosis, as gauged by the increase in exercise cardiac frequency above the level predicted from anthropometric measurements.
2. Twenty patients were studied postoperatively. In the 12 who showed clinical improvement the exercise ventilation and cardiac frequency were reduced and the exercise tidal volume at a given minute ventilation was increased. The latter change occurred despite a reduction in vital capacity, which was probably a residual effect of thoractomy. There was no significant change in the response to breathing carbon dioxide. No material change in function was observed in the patients whose condition was not improved by the operation.
3. It is suggested that in mitral stenosis the tachypnoea which occurs during exercise, whilst mainly a mechanical consequence of the reduced vital, capacity, is also partly due to pulmonary congestion stimulating intrapulmonary receptors.
The Relationship of Urinary Kallikrein Activity to Renal Salt and Water Excretion
Authors: Levy S. B. , Frigon R. P. , Stone R. A. 
Published: August 2015

1. We measured urinary kallikrein (kininogenin) excretion in black and white normotensive subjects during a variety of manipulations of salt and water balance.
2. A large intravenous saline load administered while the subjects were on an unrestricted sodium diet did not significantly change urinary kallikrein activity in either racial group.
3. After several days of dietary sodium restriction both racial groups increased their urinary kallikrein activity. An intravenous water load given then further increased urinary kallikrein activity. White subjects were studied for an additional 24 h period, and urinary kallikrein activity returned to pre-water load values, indicating that the excretion of a water load in sodium-depleted subjects is associated with an increase in kallikrein excretion.
4. Black subjects excreted less kallikrein in the urine than white subjects during the initial 24 h periods of unrestricted dietary sodium intake, but there were no other significant racial differences during the other experimental conditions.
Uptake by Bone of Pyrophosphate, Diphosphonates and their Technetium Derivatives
Authors: Bisaz Sylvia , Jung A. , Fleisch H. 
Published: August 2015

1. The uptake of inorganic pyrophosphate (PPi) from blood to bone was investigated in the rat in vivo.
2. PPi is taken up by the bone, where it appears both as PPi and as inorganic orthophosphate (Pi). The latter is due at least partly to local hydrolysis.
3. The fraction of injected PPi taken up by bone, measured as total Pi, was in the same range as that of technetium—tin—PPi, diphosphonates, technetium—tin—ethane-1-hydroxy-1,1-diphosphonate and Pi, but lower than that of calcium.
4. The plasma half-life of PPi is in the same order of magnitude as that of technetium—tin—PPi, diphosphonates, technetium—tin—ethane-1-hydroxy-1,1-diphosphonate, Pi and calcium.
5. PPi, diphosphonates and their technetium complexes are only partly ultrafiltrable in plasma.
6. It appears that the technetium complexes behave in a similar fashion to free PPi or diphosphonate.
Metabolic and Body Temperature Changes during Exercise in Hyperthyroid Patients
Authors: Nazar K. , Chwalbińska-Moneta J. , MacHalla J. , Kaciuba-UściłKo H. 
Published: August 2015

1. Body temperature, blood glucose, lactate, plasma free fatty acid and noradrenaline responses to exercise were studied in hyperthyroid patients during 30 min exercise on a bicycle ergometer at a work load producing a heart rate of approximately 135–140 beats/min. The results were compared with those obtained in healthy subjects exercising at work loads comparable in terms of oxygen uptake.
2. External auditory canal temperature at rest was 0·5°C higher in hyperthyroid patients than in control subjects but the exercise-induced increases in body temperature were similar in both groups.
3. Pre-exercise blood glucose concentration was higher in the thyrotoxic patients than in normal subjects. During exercise blood glucose decreased markedly in the patients whereas in the control subjects the exercise-induced changes in blood glucose were insignificant.
4. There was no difference between the groups in the pre-exercise blood lactate and plasma free fatty acid concentrations. Significantly greater increases in blood lactate and plasma free fatty acids were found during exercise in hyperthyroid patients than in the control subjects.
5. Resting plasma noradrenaline concentration in the hyperthyroid patients did not differ from that found in normal subjects, but the exercise-induced increases in plasma noradrenaline were greater in the patients than in the control group.
6. On the basis of heart rate, as well as of body temperature and blood lactate differences between the hyperthyroid patients and healthy control subjects, it appears that the patients exercising at similar oxygen uptake as normal subjects were under greater physiological strain.
The Occurrence of Folate-Derived Pteridines in Rat Liver
Authors: Reed Berenice , Weir D. , Scott J. 
Published: August 2015

1. It has previously been shown that folate polyglutamates in the rat are catabolized almost exclusively via cleavage of the C-9—N-10 bond, resulting in the formation of pteridines and p-aminobenzoylglutamate. The latter catabolite is rapidly excreted, appearing in the urine as acetamidobenzoylglutamate and is undetectable in rat liver.
2. The pteridines catabolites on the other hand are retained to a much greater extent by the liver, forming an ever-increasing proportion of the retained radioactive tracer.
3. A possible role for these pteridines as cofactors in brain metabolism is discussed.