bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ventilatory effects of hypoxia and adenosine infusion in patients after bilateral carotid endarterectomy
Authors: Griffiths T. L. , Warren S. J. , Chant A. D. B. , Holgate S. T. 
Published: August 2015

1. We have studied the carotid body contribution to hypoxic respiratory drive, using a hypoxic/hyperoxic switching technique, and the ventilatory response to intravenous infusion of adenosine, a recently described respiratory stimulant, in five patients with bilateral carotid endarterectomy.
2. The contribution made by the carotid bodies to total ventilatory drive during hypoxia varied from 2.5% to 45.9%.
3. The ventilatory response to adenosine infusion varied from a 7% decrease to a 25% increase in ventilation.
4. Those patients with intact hypoxic ventilatory drive showed respiratory stimulation, whereas of the two patients with attenuated chemoreflexes, one showed no stimulation and the other depression of ventilation in response to adenosine infusion.
5. We conclude that adenosine exerts its respiratory stimulant effect via an action on the peripheral chemoreceptors. This may coexist with a centrally mediated respiratory depression that is masked when the carotid bodies are intact.
Effect of atrial natriuretic peptide on blood pressure, guanosine 3′:5′-cyclic monophosphate release and blood volume in uraemic patients
Authors: Jespersen B. , Eiskær H. , Pedersen E. B. 
Published: August 2015

1. Eleven patients on chronic maintenance dialysis were investigated before and after intravenous bolus injection of atrial natriuretic peptide (2 μg/kg body weight).
2. Mean blood pressure was reduced to the same extent in the uraemic patients as in 11 healthy subjects, with a nadir 3 min after the atrial natriuretic peptide injection at which time mean blood pressure was reduced by 13% (median) in the uraemic patients and 11% in the healthy subjects.
3. Basal plasma atrial natriuretic peptide and guanosine 3′:5′-cyclic monophosphate levels were higher in the uraemic patients than in the healthy subjects, but guanosine 3′:5′-cyclic monophosphate increased markedly in both groups after atrial natriuretic peptide injection.
4. Using changes in γ-emission from blood after previous labelling of erythrocytes with 51Cr, and changes in packed cell volume, haemoglobin and erythrocyte count, a reversible shift of fluid from the intravascular phase was demonstrated in the uraemic subjects. The blood volume was maximally reduced by 6% (median) of initial blood volume at 30 min after atrial natriuretic peptide injection.
5. Correlation analyses gave no evidence of a causal relationship between the changes in mean blood pressure and changes in blood volume, angiotensin II, aldosterone or arginine vasopressin after atrial natriuretic peptide injection.
6. It is concluded that a pharmacological dose of atrial natriuretic peptide reduces blood pressure in uraemic patients on maintenance dialysis to the same extent as in healthy subjects. The blood-pressure-reducing effect of atrial natriuretic peptide does not seem to be mediated by its diuretic effect or ability to displace fluid from plasma to the interstitial fluid compartment.
A cross-sectional study of basal platelet intracellular free calcium concentration in normotensive and hypertensive primigravid pregnancies
Authors: Kilby M. D. , Pipkin F. Broughton , Cockbill S. , Heptinstall S. , Symonds E. M. 
Published: August 2015

1. The intracellular free calcium concentration ([Ca2+]i) in washed human platelets was measured using the fluorescent indicator, fura-2, in a cross-sectional study of 36 normotensive, primigravid volunteers, 12 in each trimester of pregnancy and a further 12 at 6 weeks post partum. The results were compared with those obtained from 30 normal female volunteers not using oral contraception.
2. The mean basal [Ca2+]i in the platelets of the pregnant women in the first two trimesters (115.6 ± 6.7 and 120.1 ± 5.7 nmol/l, respectively) was not shown to differ significantly from that of normal non-pregnant volunteers (112.3 ± 2.9 nmol/l). However, during the third trimester a significant increase in [Ca2+]i was noted (134.0 ± 4.9 nmol/l; P &lt; 0.05), with a return to normal values in the post-partum period (108.2 ± 6.1 nmol/l).
3. [Ca2+]i was also measured in the platelets of a group of 12 primigravid pregnant women in the third trimester whose pregnancies were complicated by gestational hypertension (pregnancy-induced hypertension and preeclampsia). A significant rise in basal [Ca2+]i was noted in the platelets of primigravidae whose pregnancies were complicated by pre-eclampsia (163.6 ± 8.8 nmol/l) as compared with normotensive, third-trimester primigravidae (P &lt; 0.02). However, no correlation could be demonstrated between [Ca2+]i and systemic blood pressure.
Arginine vasopressin release from human platelets after irreversible aggregation
Authors: Anfossi Giovanni , Mularoni Elena , Trovati Mariella , Massucco Paola , Mattiello Luigi , Emanuelli Giorgio 
Published: August 2015

1. The release of arginine vasopressin from human platelets was investigated in platelet-rich plasma after irreversible aggregation induced by adenosine 5′-pyrophosphate, collagen, sodium arachidonate, thrombin and adrenaline in vitro.
2. Arginine vasopressin levels were significantly higher in the supernatant from stimulated platelet-rich plasma than from unstimulated samples, reaching 3.5 × 10−12 (range 1.6–12.5 × 10−12) mol/l in the absence of an aggregating agent, 8.8 × 10−12 (range 4.2–17.5 × 10−12) mol/l after adenosine 5′-pyrophosphate, 13.7 × 10−12 (2.2–63.2 × 10−12) mol/l after collagen, 7.8 × 10−12 (2.2–14.6 × 10−12) mol/l after sodium arachidonate, 7.8 × 10−12 (2.2–16.3 × 10−12) mol/l after thrombin and 12.2 × 10−12 (4.8–32.1 × 10−12) mol/l after adrenaline.
3. An arginine vasopressin level of 18 × 10−12 mol/l, which can be achieved physiologically, increased the sensitivity of platelets to adenosine 5′-pyrophosphate and collagen in vitro; the same concentration of arginine vasopressin caused a potentiation of the effect of catecholamines on the response of platelets to sodium arachidonate.
4. These results indicate that intraplatelet arginine vasopressin is released during aggregation and suggest that a local release of arginine vasopressin could occur after complete platelet aggregation in vivo.
Actions of bufalin and cinobufotalin, two bufadienolides respectively more active and less active than ouabain, on ouabain binding and 86Rb uptake by human erythrocytes
Authors: Brownlee A. A. , Johnson Paul , Mills Ivor H. 
Published: August 2015

1. We have reported that the bufadienolide, bufalin (purified from toad skin), was more potent than ouabain in inhibiting the sodium/potassium-dependent adenosine triphosphatase from canine kidney (Sigma) [Brownlee, A. A., Lee, G. & Mills, I. H. J. Physiol. (London) 1987; 390, 94P].
2. The activities of bufalin and cinobufotalin were compared with ouabain in the [3H]ouabain binding assay and on 86Rb uptake in human erythrocytes.
3. When the percentage binding of ouabain-sensitive [3H]ouabain was plotted against the log of the concentration of drug in mol/l, it was shown that the bufalin curve was shifted to the left of that of ouabain and that of cinobufotalin was to the right
4. Linear regression lines were fitted to the data transformed as the log of (p/1–p) plotted against the log of the drug concentration, where p is the proportion of maximal ouabain-sensitive activity at the drug concentration being considered. The IC50 (the concentration of drug producing a 50% change in the maximal ouabain-sensitive response) was 1.4 × 10−9 mol/l for bufalin, 9.7 × 10−9 mol/l for ouabain and 1.70 × 10−7 mol/l for cinobufotalin.
5. The introduction of bufalin 1 h before ouabain reduced the binding of [3H]ouabain to 23.4 ± 1.5% (P &lt; 0.001). Bufalin added in the second hour reduced the ouabain-sensitive binding from 100 ± 1.9% to 87.4 ± 2.9% (P &lt; 0.01).
6. The oubain-sensitive 86Rb uptake curves showed that that of bufalin was to the left of ouabain and that of cinobufotalin was to the right.
7. Regression lines were fitted to the 86Rb uptake data as described for the ouabain-binding data. The IC50 was 1.05 × 10−8 mol/l for bufalin, 4.4 × 10−8 mol/l for ouabain and 4.3 × 10−7 mol/l for cinobufotalin.
8. The differences in potencies are not all explained by what is known of the effects of structure on the cardiac toxicity of cardenolides and bufadienolides.
Effects of haemorrhage and volume expansion on portal–systemic collateral vascular resistance in conscious portal hypertensive rats
Authors: Koshy Abraham , Sekiyama Tatsuya , Cereda Jean-Michel , Hadengue Antoine , Girod Catherine , Lebrec Didier 
Published: August 2015

1. In order to study the acute effects of blood volume changes on the vascular resistance of portal-systemic collaterals (collateral vascular resistance), a model of total portal vein occlusion with 100% portal-systemic shunts was developed in the rat. In this model, we determined the haemodynamic effects of haemorrhage (1.8 ml/100 g body weight) or intravenous infusion of a volume expander (1.8 ml/100 g body weight). Cardiac output and regional blood flows were measured by the radioactive microsphere method.
2. Haemorrhage significantly reduced arterial pressure from 108 ± 4 to 92 ± 4 mmHg (mean ± sem), cardiac output from 56 ± 4 to 24 ± 2 ml min−1 100 g−1 body weight, portal pressure from 15.1 ± 1.5 to 10.0 ± 1.4 mmHg and portal tributary blood flow from 19.9 ± 2.3 to 8.3 ± 1.4 ml/min. Consequently, collateral vascular resistance significantly increased from 6.6 ± 0.9 × 103 to 11.1 ± 2.0 × 103 kPal−1 s.
3. Volume expansion reduced arterial pressure from 98 ± 3 to 90 ± 3 mmHg, and significantly increased cardiac output from 43 ± 3 to 55 ± 3 ml min−1 100 g−1 body weight, portal pressure from 13.9 ± 0.7 to 16.5 ± 0.8 mmHg and portal tributary blood flow from 16.4 ± 1.3 to 28.2 ± 3.2 ml/min. Consequently, collateral vascular resistance significantly decreased from 7.0 ± 0. 5 × 103 to 4.9 ± 0.4 × 103 kPa l−1 s.
4. This study shows that in rats with portal hypertension, portal-systemic collateral vascular resistance is modified by alterations in blood volume.
A comparison of the acute effects of subcutaneous and intranasal calcitonin
Authors: O'Doherty D. P. , Bickerstaff D. R. , McCloskey E. V. , Atkins R. , Hamdy N. A. T. , Kanis A. 
Published: August 2015

1. We studied the acute effects of intranasal and subcutaneous calcitonin in 40 patients with active Paget's disease of bone. Patients received a single dose of either 400 units of calcitonin delivered as a nasal spray, or 1, 10 or 100 units of subcutaneous calcitonin, or placebo.
2. Subcutaneous salmon calcitonin, administered at doses of 1, 10 and 100 units to nine patients with Paget's disease of bone, induced a dose-dependent fall in the serum calcium. This calcium-lowering effect was not seen with a second group of nine patients receiving placebo.
3. The lower doses of calcitonin had significant effects, and these were more pronounced in patients with lower rates of bone turnover.
4. Four hundred units of calcitonin administered as a nasal spray induced effects qualitatively similar to those seen with subcutaneous calcitonin, with an efficacy equivalent to approximately 30 units of subcutaneous calcitonin.
5. We conclude that the bioequivalence of calcitonin given by intranasal insufflation is low compared with its parenteral administration. The intranasal route may be more appropriate for managing patients with disorders associated with low bone turnover.
Alterations in Na+, K+ and Ca2+ transport in erythrocytes of patients with carcinomas of the head and neck: possible role of mild anaemia and cell age
Authors: Engelmann Bernd , Grevers Gerhard , Janka Hans Uwe , Duhm Jochen 
Published: August 2015

1. Rates of erythrocyte Ca2+ inward transport, activities of erythrocyte Ca2+-adenosine triphosphatase, Na+, K+ pump, Na+-K+ co-transport and Na+-Li+ exchange, and erythrocyte Ca2+, K+ and Na+ contents have been determined in patients with carcinomas of the head and neck.
2. Decreases in Ca2+ inward transport and Na+-K+ co-transport activity, and increases in erythrocyte Ca2+ and K+ contents, were observed.
3. The more pronounced changes found in advanced carcinoma stages proved to be related to a 50% incidence of a mild anaemia of chronic disease in patients with carcinoma stages T3 and T4.
4. ‘Young’ (light) erythrocytes from healthy donors obtained by density centrifugation showed modifications in Na+ transport and K+ content similar to those seen in the patients.
5. It is concluded that the decrease in Na+-K+ co-transport activity, as well as the elevated K+ content and the lowered mean corpuscular haemoglobin content, but not the disturbances in Ca2+ homoeostasis, in erythrocytes of patients with carcinomas of the head and neck are most probably due to the occurrence of a mild anaemia of chronic disease in advanced carcinoma stages, associated with a reduction in mean erythrocyte age.
Atrial natriuretic factor and changes in dietary sodium intake in patients with chronic renal failure
Authors: Dussaule J. C. , Michel C. , Wolf J. P. , Czekalski S. , Mignon F. , Ardaillou R. 
Published: August 2015

1. In order to examine the potential role of atrial natriuretic factor in modulating the increased sodium excretion per nephron in chronic renal failure, we studied 12 uraemic patients on the last day of two successive 7 day periods during which their sodium intake was 100 and 20 mmol of sodium/day, respectively.
2. There was a parallel decrease from 6.31 ± 0.75 to 2.17 ± 0.32% in the fractional excretion of filtered sodium and from 234.4 ± 74.9 to 80.6 ± 20.3 pg/ml (supine position) or 140.1 ± 43.6 to 60.7 ± 14.6 pg/ml (upright position) in plasma atrial natriuretic factor. Both parameters were significantly correlated during the two periods of different sodium intake (P &lt;0.05). The ratio of plasma guanosine 3′:5′-cyclic monophosphate to plasma creatinine changed proportionally to plasma atrial natriuretic factor. Plasma aldosterone and plasma renin activity increased during the sodium-depleted period but only plasma renin activity was significantly correlated with fractional excretion of filtered sodium.
3. The predominant role of atrial natriuretic factor compared with that of aldosterone in the renal response to varying sodium intake is suggested both by regression analysis and by the effect of 5 day's treatment with a converting enzyme inhibitor (enalapril) in six other uraemic patients on a normal (100 mmol/day) sodium intake. Such treatment, although resulting in a significant increase in plasma renin activity and a significant decrease in plasma aldosterone, at least in the supine position, did not modify the fractional excretion of sodium and plasma atrial natriuretic factor.
4. Taken together, these results suggest a role for plasma atrial natriuretic factor in promoting the adaptation of sodium excretion on chronic changes of sodium intake in patients with chronic renal failure.
Peptide histidine valine: Its haemodynamic actions and pharmacokinetics in man differ from those of vasoactive intestinal peptide and peptide histidine methionine
Authors: Gill J. S. , Yiangou Y. , Webb D. J. , Meleagros L. , Benjamin N. , Chrysanthou B. J. , Cockcroft J. R. , Causon R. C. , Camm A. J. , Bloom S. R. 
Published: August 2015

1. The effects of intravenous and intra-arterial infusion of the peptides derived from prepro-vasoactive intestinal peptide, vasoactive intestinal peptide, peptide histidine methionine and peptide histidine valine, were examined in six healthy volunteers.
2. Vasoactive intestinal peptide given intravenously caused a significant increase in heart rate and a decrease in diastolic, but not systolic, blood presure, whereas peptide histidine valine caused an increase in heart rate alone, despite higher achieved circulating peptide concentrations. Peptide histidine methionine did not affect heart rate or blood pressure. Forearm blood flow was increased by vasoactive intestinal peptide and peptide histidine valine when infused locally intra-arterially, although vasoactive intestinal peptide was more potent than peptide histidine valine.
3. Plasma concentrations of cardiodilatin (the N-terminal peptide derived from pro-atrial natriuretic peptide) were increased by intravenous infusion of vasoactive intestinal peptide, but were unaffected by peptide histidine methionine or peptide histidine valine. Circulating plasma concentrations of adrenaline and noradrenaline did not change during infusion of vasoactive intestinal peptide, peptide histidine methionine or peptide histidine valine.
4. Peptide histidine valine had a long half-life when compared with peptide histidine methionine and vasoactive intestinal peptide.
5. We conclude that peptide histidine valine is active in the human cardiovascular system and has a similar, though less potent, vasodilating action to vasoactive intestinal peptide. The higher circulating levels of peptide histidine valine found in man suggest that it may be important in modulating vascular tone.
Renal tubular reabsorption of sodium and water during infusion of low-dose dopamine in normal man
Authors: Olsen N. V. , Hansen J. M. , Ladefoged S. D. , Fogh-Andersen N. , Leyssac P. P. 
Published: August 2015

1. Using the renal clearance of lithium (CLi) as an index of proximal tubular outflow of sodium and water, together with simultaneous measurements of effective renal plasma flow, glomerular filtration rate (GFR) and sodium clearance (CNa), renal function and the tubular segmental reabsorption rates of sodium and water during dopamine infusion (3 μg min−1 kg−1) were estimated in 12 normal volunteers.
2. CNa increased by 128% (P &lt;0.001). Effective renal plasma flow and GFR increased by 43% (P &lt;0.001) and 9% (P &lt;0.01), respectively. CLi increased in all subjects by, on average, 44% (P &lt;0.001). Fractional proximal reabsorption [1-(CLi/GFR)] decreased by 13% after dopamine infusion (P &lt;0.001), and estimated absolute proximal reabsorption rate (GFR–CLi) decreased by 8% (P &lt;0.01). Absolute distal sodium reabsorption rate [(CLi–CNa) × PNa, where PNa is plasma sodium concentration] increased (P &lt;0.001), and fractional distal sodium reabsorption [(CLi–CNa)/CLi] decreased (P &lt;0.001).
3. It is concluded that natriuresis during low-dose dopamine infusion is caused by an increased outflow of sodium from the proximal tubules that is not fully compensated for in the distal tubules.
Skeletal muscle metabolism in the leg during exercise in patients with congestive heart failure
Authors: Marie Pierre-Yves , Escanye Jean-Marie , Brunotte François , Robin Brigitte , Walker Paul , Zannad Faiez , Robert Jacques , Gilgenkrantz Jean-Marie 
Published: August 2015

1. Using 31P nuclear magnetic resonance, it has previously been demonstrated that patients with congestive heart failure exhibit a greater than normal phosphocreatine (PCr) depletion in the working skeletal muscles of the arm. We have studied the importance of the work necessary to reach a similar PCr depletion {[PCr]/([PCr] + [Pi]) = 0.5} in calf muscle. Our results show significantly lower values for patients with congestive heart failure in both aerobic and ischaemic conditions (respectively: 0.009 ± 0.007 vs 0.026 ± 0.013 W/kg body weight, P &lt;0.01; 0.29 ± 0.16 vs 0.90 ± 0.25 J/kg body weight, P &lt;0.01).
2. This original model of skeletal muscle exercise facilitates a comparison of PCr recovery rate due to a similarity in the PCr depletion and intracellular pH in the two series at the start of recovery. However, the PCr recovery rate is similar after both normoxic and ischaemic exercise, i.e. respective percentages of PCr increase in the first 25 s recovery spectrum were: (a) aerobic exercise, congestive heart failure 133 ± 18%, control series 138 ± 18%; (b) ischaemic exercise, congestive heart failure 114 ± 13%, control series 118 ± 12%. The absence of a difference in PCr recovery rate and the greater PCr depletion by ischaemic work in patients with congestive heart failure suggest modifications that cannot be explained by a reduced blood flow to the muscle.
3. When comparing the two series, intracellular pH evolved similarly in normoxia and ischaemia during both work and recovery. Thus, no increase in anaerobic glycolytic activity appears when equivalent PCr depletion has occurred.
Changes in skin blood flow during the menstrual cycle: The influence of the menstrual cycle on the peripheral circulation in healthy female volunteers
Authors: Bartelink M. L. , Wollersheim H. , Theeuwes A. , van Duren D. , Thien Th. 
Published: August 2015

1. It is known that females have a lower skin perfusion than males. In women there are also differences in blood flow at different reproductive stages of their lives. As an initial investigation of the possible contribution of sex hormones to these differences, we studied skin and forearm blood flow during the natural changes in hormone levels which occur during the menstrual cycle.
2. Thirty-one healthy female volunteers were studied. The effect of a standardized finger cooling test (immersion of a gloved hand in a 16°C water bath) on finger skin temperature and on laser Doppler flux in the finger, and forearm blood flow (strain gauge venous occlusion plethysmography) was assessed at four different times during one cycle: during menstruation, 1 day before ovulation, 2 days after ovulation and at the mid-luteal phase. Test days were determined by daily measurements of basal body temperature and were confirmed afterwards by determinations of serum luteinizing hormone, follicle-stimulating hormone, 17β-oestradiol and progesterone.
3. Peripheral skin circulation varied significantly within one menstrual cycle. The extremes were a mean finger skin temperature of 25.9 ± 3.0°C in the luteal phase compared with 28.4 ± 3.7°C in the pre-ovulatory phase (P = 0.002). The respective values for the mean laser Doppler flux were 18.4 ± 10.9 compared with 29.2 ± 16.4 arbitrary units (P = 0.003).
4. Baseline forearm muscle blood flow also varied significantly (P = 0.04) within one menstrual cycle, with low values in the menstrual phase compared with the other phases.
5. In conclusion, we have shown that peripheral skin circulation and forearm muscle blood flow exhibit significant variability during the hormonal changes in a menstrual cycle.
Ventilatory responses to hypercapnia and hypoxia in patients with eucapnic morbid obesity before and after weight loss
Authors: Chapman K. R. , Himal H. S. , Rebuck A. S. 
Published: August 2015

1. To examine the relationship between eucapnic morbid obesity and ventilatory responsiveness to chemical stimuli, we measured hypercapnic and hypoxic ventilatory responses in 29 patients (26 women, three men) before and 3–6 months after gastroplasty. No subject demonstrated resting awake hypercapnia and none suffered from sleep-disordered breathing.
2. Mean weight fell significantly (122.8 ± 21.4 vs 102.2 ± 22.8 kg, P &lt;0.0001) and functional residual capacity rose slightly but significantly (1.94 ± 0.58 vs 2.18 ± 0.64 litres; P &lt;0.05) after weight loss.
3. The hypercapnic ventilatory response slope fell significantly after weight loss (2.88 ± 2.27 vs 2.24 ± 1.06 litres min−1 mmHg−1, P &lt;0.05) with a significant shift of the ventilatory response curve to the right. There were no statistically significant changes in the patterns of ventilatory response.
4. In addition, isocapnic hypoxic ventilatory response slopes, measured at two levels of carbon dioxide partial pressure, fell significantly after weight loss. These changes were accompanied by significant shifts of the ventilatory response curves to the left, such that, for a given oxygen saturation, mean ventilation was significantly lower in the less obese state. Similarly to hypercapnic responses, there were no statistically significant changes in ventilatory pattern despite the changes in overall ventilatory response.
5. We conclude that ventilatory responsiveness to chemical simuli is increased in obese subjects who maintain adequate alveolar ventilation while awake.