bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of posture on the metabolic and ventilatory response to low level steady state exercise
Authors: Weissman Charles , Askanazi Jeffrey , Rosenbaum S. H. , Hyman Allen I. , Milic-Emili J. , Kinney John M. 
Published: August 2015

1. Low level exercise is frequently used to assess cardiac and pulmonary function. This study examines the differences in both metabolic and respiratory patterns between the sitting and supine position.
2. Six normal male subjects were studied in both positions during four levels of exercise (12.5, 25, 37.5 and 50 W). Oxygen consumption (Vo2), carbon dioxide production (Vco2) and minute ventilation (Ve2) were greater when sitting as were the ventilatory equivalents to O2 (Ve2/ Vo2) and CO2 (Ve2/ Vco2).
3. Respiration was compared at equivalent workloads; the greater minute ventilation observed during sitting was due to greater tidal volumes (Vt) and mean inspiratory flows (Vt/Vi,). Expiratory time (Te) was longer and inspiratory duration shorter under most conditions when sitting.
4. When breathing patterns were compared at similar degrees of minute ventilation, Vt, Te and Vt/Ti were greater when sitting, while respiratory frequency (fr) was slower.
The differential effect of arginine vasopressin on skin blood flow in man
Authors: Wiles P. G. , Grant P. J. , Davies J. A. 
Published: August 2015

1. Physiological elevation of plasma vasopressin in man results in a small reduction in skeletal muscle blood flow but the action on skin blood flow has not been reported.
2. We have studied eight male subjects during infusion of arginine vasopressin (AVP) at 2 units/h for 90 min. Plasma levels of AVP, measured by radioimmunoassay, rose to 68.5 (7.0) pg/ml, mean (sem). Forearm and finger blood flow was measured with an electronic plethysmograph, hand interdigital skin-fold blood flow with a laser-Doppler blood flow meter and facial temperature with a thermocouple.
3. All subjects developed marked facial pallor during infusion of AVP, facial temperature falling from 34.2 (0.2) to 32.7 (0.1)°C (P &lt; 0.001) then rising to 33.7 (0.1)°C (P &lt; 0.01) after AVP was stopped. Hand interdigital skin-fold blood flow also fell from 2.6 (0.02) to 2.3 (0.02) V (P &lt; 0.001) and rose sharply to 3.6 (0.2) V (P &lt; 0.001) on stopping the infusion. There were small changes in forearm and finger blood flow: both rose, from 6.3 (0.1) to 6.9 (0.1) (P &lt; 0.001) and 46.1 (1.0) to 54.3 (0.7) ml min−1 100 ml−1 (P &lt; 0.001) respectively. Neither fell when AVP was stopped. Heart rate remained unchanged throughout.
4. These results indicate that high physiological levels of AVP, comparable with those attained during physical stress, produced a fall in blood flow in the face and interdigital skin-fold of the hand consistent with a fall in nutritional blood flow to skin. Blood flow to skeletal muscle, however, remained little changed whereas that through arteriovenous anastomoses in skin of the finger rose.
5. We conclude that AVP has a selective vasoactive effect in skin, constricting nutritional blood vessels and venules while promoting an increase in arteriovenous shunting of blood.
Changing effects on erythrocyte sodium and potassium during the development of chronic renal failure with anaemia in rats
Authors: Thomas T. H. , Mason C. , Illingworth K. M. 
Published: August 2015

1. Rats were studied 7 days and 17 days after the onset of renal failure which was induced by a surgical technique.
2. Plasma urea, creatinine (PCr) and potassium had increased after 7 days; plasma potassium increased much more after 17 days but PCr was slightly lower.
3. Renal failure caused resetting of erythropoietic control to a lower level of packed cell volume (PCV). After 7 days renal failure some rats had a low PCV, whereas others still had a normal PCV apparently due to slower erythrocyte destruction of pre-renal failure cells.
4. After 7 days renal failure, rats with a normal PCV had an increased erythrocyte membrane leak to potassium that resulted in a low erythrocyte potassium [K+]RBC. This was accompanied by an increase in active sodium pump units [increased ouabain sensitive sodium flux (Fo) and its rate constant (ko)] that caused erythrocyte sodium ([Na+]RBC) to fall. The increased active pump units retarded the fall in [K+]RBC and may have extended the life of the normal erythrocytes in the renal failure environment.
5. The PCV was below normal in all rats after 17 days renal failure. [K+]RBC was increased and since ko was normal there appeared to be compensation to produce erythrocytes with reduced membrane leak to potassium with longer standing renal failure.
6. PCr was only related to PCV after 17 days renal failure and not in the earlier phase of erythrocyte destruction. The changes in erythrocyte membrane permeability were very significantly related to PCV after 17 days.
Effects of intra-arterial arginine-vasopressin infusions on peripheral blood flows in conscious dogs
Authors: Liard Jean-Francois 
Published: August 2015

1. We reported in an earlier study that intravenous infusions of arginine-vasopressin (AVP), 220 pg min−1 kg−1 for 1 h, substantially reduced blood flow to the skin, skeletal muscle, pancreas, colon, small intestine, abdominal fat and myocardium [1] in conscious dogs. In the present study, we infused AVP directly into the artery supplying these organs and tissues in order to determine the relative contribution of local versus systemic mechanisms in the vascular resistance changes previously observed.
2. Regional blood flows were measured with radioactive microspheres in conscious, chronically instrumented dogs before and during intra-arterial infusions of AVP administered into the left axillary artery (n = 6), the left coronary artery (n = 6), and the cranial mesenteric artery (n = 6). The infusion rates were calculated to increase local, target organ plasma concentrations of AVP to the levels reached in our previous study while minimizing systemic changes.
3. Left axillary AVP artery infusion significantly reduced skin and compact bone blood flow, but had no effect on skeletal muscle blood flow. Intra-coronary AVP infusion had no effect on myocardial blood flow nor on cardiac output. Intramesenteric AVP infusion had no effect on blood flow to the colon, small intestine and abdominal fat, but significantly reduced blood flow to those areas of the pancreas which received blood from the cannulated artery.
4. Measurements in a limited number of dogs indicated that the local axillary and mesenteric venous levels of AVP were similar when the hormone was infused systemically at a rate of 220 pg min−1 kg−1 or intra-arterially at a lower rate.
5. These findings suggest that the increase in resistance measured in the skeletal muscle, small intestine, colon and abdominal fat after systemic administration of small amounts of AVP results in large part from indirect mechanisms. Direct vasoconstrictor effects of AVP at these plasma concentrations appear limited to the skin, the pancreas and the compact bones.
Prostacyclin in the circulation of patients with vascular disorders undergoing surgery
Authors: Ritter J. M. , Hamilton G. , Barrow S. E. , Heavey D. J. , Hickling N. E. , Taylor K. M. , Hobbs K. E. F. , Dollery C. T. 
Published: August 2015

1. The object of this study was to investigate clinical conditions in which increased production of prostacyclin (PGI2) has been reported. 6-Oxo-prostaglandin F1α (6-oxo-PGF1α) is the stable hydrolysis product of PGI2 and was measured in plasma from patients undergoing hepatic or cardiac surgery and in unoperated patients with vascular and hepatic disease, using gas chromatography/mass spectrometry.
2. Blood obtained simultaneously from portal and peripheral veins, during emergency surgery for bleeding oesophageal varices in six patients with cirrhosis of the liver, contained very high concentrations of 6-oxo-PGF1α (range 99–11485 pg/ml of plasma). 6-Oxo-PGF1α was higher in portal than in peripheral blood in five out of six patients.
3. Six unoperated patients with cirrhosis and oesophageal varices which were not bleeding all had normal peripheral plasma concentrations of 6-oxo-PGF1α &lt; 2 pg/ml (normal up to 5 pg/ml).
4. Seventeen patients with severe vascular disease had normal basal plasma 6-oxo-PGF1α concentrations (&lt; 2 pg/ml).
5. Eighteen subjects with atheromatous coronary artery disease underwent aorta–coronary artery grafting, and plasma concentrations of 6-oxo-PGF,α were markedly elevated during surgery (range 55–1207 pg/ml).
6. We conclude that surgery stimulates PGI2 production substantially, and argue that the function of PGI2 may be to limit intravascular extension of thrombus from sites of haemostasis. Inappropriate PGI2 synthesis may contribute to the massive haemorrhage characteristic of oesophageal variceal bleeding.
Plasma atrial natriuretic peptide: Its relationship to changes in sodium intake, plasma renin activity and aldosterone in man
Authors: Sagnella Giuseppe A. , Markandu Nirmala D. , Shore Angela C. , Forsling Mary L. , MacGregor Graham A. 
Published: August 2015

1. Plasma levels of immunoreactive atrial natriuretic peptide (IrANP), plasma renin activity, aldosterone and vasopressin were measured in 11 normotensive subjects on a low (10 mmol/day), a normal (150 mmol/day) and a high (350 mmol/day) sodium intake.
2. Plasma levels of IrANP increased significantly with increasing dietary sodium intake with levels (means ± sd) of 3.9 ± 2.1 pg/ml on the fifth day of the low sodium diet, 6.1 ± 3.4 pg/ml on the fifth day of the normal sodium diet and 11.4 ± 4.6 pg/ml on the fifth day of the high sodium diet.
3. Plasma renin activity and aldosterone decreased significantly with increasing sodium intake whereas plasma vasopressin was highest on the high sodium intake.
4. These results suggest that the atrial peptides may be a new and important component in the overall control of sodium and water balance during increased sodium intake.
The role of RT1 antigen differences in semi-allogeneic rat pregnancy
Authors: Power D. A. , Cunningham C. , Catto G. R. D. 
Published: August 2015

1. The immunological mechanisms involved in sustaining normal semi-allogeneic pregnancies and in the enhancement of organ allografts were investigated in inbred rats.
2. The antigenic targets for alloantibodies formed after leucocyte transfusions and multiple allogeneic pregnancies were defined by the EA rosette inhibition (EAI) assay in several congenic and recombinant inbred rat strains.
3. Alloantibodies produced by leucocyte immunization (conventionally induced antisera) were directed only to RT1-encoded (major histocompatibility complex, MHC) antigens. Both RT1A (class I MHC) and either RT1B, D (class II MHC) or RT1C (Qa-like) antigens were targets for these alloantibodies; responses to the latter three antigens could not be separated with available congenic recombinant inbred rat strains.
4. Alloantibodies produced as a consequence of multiple semi-allogeneic pregnancies (pregnancy-induced antisera) were directed only to RT1A antigens.
5. Allogeneic pregnancies in which the paternal strain differed from the maternal strain only at the RT1A gene locus produced suppression of a subsequent maternal immune response.
Studies in vivo and in vitro of terbutaline-induced β-adrenoceptor desensitization in healthy subjects
Authors: Martinsson Arne , Larsson Kjell , Hjemdahl Paul 
Published: August 2015

1. β-Adrenoceptor function was studied in eight healthy subjects before, during and 24 and 72 h after cessation of 2 weeks continuous oral treatment with the β2-adrenoceptor agonist terbutaline (sustained release, 7.5 mg twice daily). In vivo, blood pressure, heart rate, plasma noradrenaline and plasma cyclic AMP responses to isoprenaline (0.01, 0.02 and 0.05 μg min−1 kg−1 intravenously) were related to the plasma concentrations of isoprenaline. For comparison, β2-adrenoceptor function was evaluated in lymphocytes in vitro by studies of isoprenaline-induced accumulation of cyclic AMP and radioligand binding studies using 125I-iodohydroxybenzylpindolol.
2. In vivo, the β2-mediated plasma cyclic AMP response to isoprenaline was markedly attenuated during terbutaline treatment and was still reduced by 38% (P &lt; 0.05) 72h. after discontinuation of treatment. The blood pressure and heart rate responses to isoprenaline were unaffected by treatment. Isoprenaline-induced elevations of plasma noradrenaline concentrations were markedly reduced during terbutaline treatment. This indicates an attenuation of isoprenaline-induced increases in sympathetic nerve function and could explain why no attenuation of the isoprenaline-induced vasodilatation was observed. Thus, plasma cyclic AMP seems to be a better marker than diastolic blood pressure when evaluating β2-adrenoceptor responsiveness in vivo in man, since it is not influenced by counter-regulatory increases in sympathetic nerve activity and/or noradrenaline overflow from sympathetic nerves.
3. In lymphocytes, the isoprenaline-stimulated cyclic AMP accumulation was reduced by 75% and the β-adrenoceptor binding sites were reduced by 40% 12 h after dosing. Also the lymphocyte β2-adrenoceptors recovered slowly after withdrawal of treatment. Normal responsiveness was not restored within 72 h after the last dose of terbutaline.
4. Thus, we obtained evidence in vivo and in vitro showing a markedly attenuated β2-adrenoceptor function, which persisted at least 72 h after discontinuation of terbutaline treatment. The slow rate of resensitization of β2-adrenoceptors after withdrawal may have practical implications in the treatment of, for example, asthma, since a state of ‘physiological β2-adrenoceptor blockade’ seems to be produced by β2-agonist treatment.
δ-Aminolaevulinic acid in plasma, cerebrospinal fluid, saliva and erythrocytes: Studies in normal, uraemic and porphyric subjects
Authors: Gorchein A. , Webber R. 
Published: August 2015

1. ô-Aminolaevulinic acid (ALA) was determined by g.l.c. with electron-capture detection. Normal plasma level was 92 nmol/l (sd = 39, n = 89, range 24–270 nmol/l).
2. ALA was undetectable in 35 of 53 samples of normal cerebrospinal fluid (limit of assay 2 nmol/l). The mean of the other 18 samples was 19 nmol/l (sd = 10, range 6–36 nmol/l).
3. Salivary ALA was generally only 10–30% of the plasma level in normal and porphyric subjects.
4. Erythrocytes of normal and porphyric subjects contained no detectable ALA and were impermeable to its entry.
5. ALA clearance correlated closely with that of creatinine, consistent with it being excreted by glomerular filtration with limited tubular reabsorption.
6. In chronic renal failure, serum ALA was elevated to a maximum of three to four times the normal, but its urinary excretion was reduced, in keeping with lessened production.
7. In two cases of acute intermittent porphyria with overwhelming neuropathy the maximum plasma levels of ALA were 9 and 12 μmol/l. Haematin infusion decreased the ALA levels but without obvious clinical benefit. Limited neurological recovery occurred without major reduction in plasma levels of ALA.
8. One subject's attack was precipitated by pregnancy. The neonate was apparently normal, despite high levels of ALA in maternal plasma throughout gestation and a high level of ALA in the cord blood.
9. The observations described here do not support the view that ALA may be directly neurotoxic.
Decreased distensibility of resistance vessels of the skin in type 1 (insulin-dependent) diabetic patients with microangiopathy
Authors: Kastrup J. , Nørgaard T. , Parving H.-H. , Lassen N. A. 
Published: August 2015

1. The distensibility of the resistance vessels of the skin at the dorsum of the foot was determined in 11 long-term type 1 (insulin-dependent) diabetic patients with nephropathy and retinopathy, nine short-term type 1 diabetic patients without clinical microangiopathy and in nine healthy non-diabetic subjects.
2. Blood flow was measured by the local 133Xexenon washout technique in a vascular bed locally paralysed by the injection of histamine. Blood flow was measured before, during and after a 40 mmHg increase of the vascular transmural pressure, induced by head-up tilt.
3. The mean increase in blood flow during headup tilt was only 24% in diabetic subjects with and 48% in diabetic patients without clinical microangiopathy, compared with 79% in normal non-diabetic subjects (P &lt; 0.0005 and P &lt; 0.05, respectively).
4. An inverse correlation between microvascular distensibility and degree of hyalinosis of the terminal arterioles in biopsies from the skin was demonstrated (r = − 0.57, P &lt; 0.001).
5. Our results suggest that terminal arteriolar hyalinosis reduces the microvascular distensibility and probably increases the minimal vascular resistance, thereby impeding hyperaemic responses.
The effect of sodium taurocholate on proximal tubular reabsorption in the rat kidney
Authors: Better O. S. , Guckian V. , Giebisch G. , Green R. 
Published: August 2015

1. Microperfusion of tubules in situ was used to study the direct effect of sodium taurocholate on reabsorption of fluid by the proximal tubule of the rat.
2. Sodium taurocholate (0.1 mmol/l) in the tubular perfusate reduced proximal tubular fluid reabsorption by approximately 30%.
3. Thus, the proximal tubule appears to be a major site at which bile salts cause a natriuresis in the rat, and possibly in obstructive jaundice in man.
Relationship between the renin–aldosterone system and atrial natriuretic polypeptide in rats
Authors: Hirata Yasunobu , Ishii Masao , Sugimoto Tokuichiro , Hiroaki Matsuoka , Ishimitsu Toshihiko , Atarashi Keiichiro , Sugimoto Tsuneaki , Miyata Atsuro , Kangawa Kenji , Matsuo Hisayuki 
Published: August 2015

1. In order to examine the relationship between the renin–aldosterone system and atrial natriuretic polypeptide (ANP), we investigated the effects of α-human atrial natriuretic polypeptide (α-hANP) on the plasma concentrations of renin (PRC) and aldosterone (PAC), as well as the effects of captopril pretreatment on the natriuresis and blood pressure reduction induced by α-hANP in rats.
2. Although α-hANP infused into conscious rats at 0.67 μg min−1 kg−1 markedly increased the urinary excretion of sodium and decreased mean arterial pressure, its infusion did not change PRC; however, it significantly lowered PAC. Frusemide infusion at 20.8 μg min−1 kg−1 induced natriuresis comparable with that of α-hANP and it elevated both PRC and PAC, but mean arterial pressure was not altered.
3. Pretreatment of rats with captopril did not have any significant influence on the acute natriuretic and hypotensive effects of α-hANP.
4. Although the inhibitory effect of ANP on the renin-aldosterone system may be involved in the chronic modulation of body fluid volume and blood pressure, this effect does not seem to be directly involved in the acute natriuretic and hypotensive effects of the peptide.
Dissociation between circulating concentrations of immunoreactive growth hormone releasing factor and growth hormone in normal human subjects
Authors: Sopwith A. M. , Penny Elizabeth S. , Lytras N. , Besser G. M. , Rees Lesley H. 
Published: August 2015

1. Using a highly specific radioimmunoassay we have measured immunoreactive human growth hormone releasing factor (ir-hGRF) concentrations in the peripheral circulation of a total of 12 normal subjects.
2. Neither insulin-induced hypoglycaemia, intravenous arginine nor oral carbohydrate caused any change in venous plasma ir-hGRF concentrations, despite the expected stimulation and suppression respectively of growth hormone secretion.
3. Growth hormone secretion was not increased by oral fat or protein but each of these two foods stimulated ir-hGRF concentrations two- to fourfold.
4. Spontaneous pulses of growth hormone secretion on control days were unaccompanied by any increase in plasma ir-hGRF.
5. The dissociation between peripheral circulating ir-hGRF and growth hormone responses demonstrated under different circumstances suggests that an important source of human growth hormone releasing factor lies outside the hypothalamus and that secretion from this source is unconnected with the normal control of pituitary growth hormone secretion.
Effect of partial ornithine carbamoyltransferase deficiency on urea synthesis and related biochemical events
Authors: Kay J. D. S. , Oberholzer V. G. , Seakins J. W. T. , Hjelm M. 
Published: August 2015

1. The biochemical response to an intravenous alanine load of 0.25 g/kg was studied in nine adult female relatives of children with ornithine carbamoyltransferase deficiency. Six were classified as affected by partial deficiency and three as unaffected.
2. The plasma ammonium concentration showed no change after the alanine load in the unaffected group, but marked increases occurred in all but one of the affected group. The maximum rate of urea synthesis after the alanine load was decreased by 37% (P = 0.02) and delayed by 43% (P = 0.02) in the affected group.
3. In the affected group a low rate of urea synthesis was associated with high urinary orotate excretion, high maximum plasma ammonium concentration and delay in the time taken to reach the maximum rate of urea synthesis (Kendall concordance W = 0.55, P &lt; 0.05).
4. The effects of a higher dose of alanine and of oral protein were compared. The alanine load of 0.25 g of alanine/kg body weight was shown to provide an adequate stimulus to urea synthesis with a more rapid return of ammonium concentration to the pre-load level than with the protein load.
5. The implication of these results in determining the distribution of flux control of urea synthesis, the discrepancy between them and predicted results and the necessary modifications to quantitative simulations are discussed.
Effects of a high K+/low Na+ diet on blood pressure in young spontaneously hypertensive rats
Authors: Sugden A. Louise , Straw James A. , Bean Barbara L. 
Published: August 2015

1. Blood pressure was measured after treatment with a high K+, a low Na+ and a combined high K+/low Na+ diet in young spontaneously hypertensive rats (SHR).
2. A high K+ diet reduced blood pressure by approximately 10 mmHg during the development of hypertension. This decrease was accompanied by a significant increase in water intake and urine volume and a significant decrease in plasma renin activity (PRA).
3. A low Na+ diet also decreased blood pressure significantly, but, in contrast to the high K+ diet, water intake and urine volume significantly decreased and PRA increased.
4. When both diets were given together, the antihypertensive effects of both were eliminated. Thus while an increase in dietary K+ and a decrease in dietary Na+ are both effective antihypertensive regimens in SHR, the mechanism of action of each appears to be different and may be antagonistic in these animals.