bluuebunny/crossref_metadata_2025_split huggingface dataset:
Circulating Dopamine: Its Effect on the Plasma Concentrations of Catecholamines, Renin, Angiotensin, Aldosterone and Vasopressin in the Conscious Dog
Authors: Ball S. G. , Tree M. , Morton J. J. , Inglis G. C. , Fraser R. 
Published: August 2015

1. Six male beagle dogs with carotid loops were infused with sodium chloride solution (150 mmol/l: saline) during control observations followed by dopamine infusion at various rates. Arterial blood samples were drawn during the control period and at the end of each period of dopamine infusion for the measurement of plasma dopamine, noradrenaline, adrenaline, renin, angiotensin II, aldosterone, vasopressin, electrolytes and packed cell volume. Blood pressure and pulse were recorded throughout.
2. The rate of infusion and plasma dopamine levels were closely correlated (r = 0.99, P &lt; 0.001). Plasma dopamine levels two to 20 times basal values produced no significant change in any of the other variables measured; levels 200 times basal values caused a significant increase (P &lt; 0.05) in plasma renin concentration; levels 2000 times basal values were associated with significant increases (P &lt; 0.05) in plasma renin and angiotensin II, packed cell volume and blood pressure, without significant changes in other measurements.
3. Circulating dopamine is unlikely to be important in the control of sodium and water metabolism.
Measurement of Hypozincaemia in Mice: A Sensitive Test for Detection of Pyrogens
Authors: Boobis Susan , Hartley Rose E. 
Published: August 2015

1. The effect of bacterial pyrogens on plasma zinc concentration in mice was studied as a method of bioassay for these substances.
2. A dose-related depression of plasma zinc concentrations was observed 4 h after intravenous injection of doses of 0.05-500 ng of purified endotoxins of Salmonella abortus equi, Shigella dysenteriae and Escherichia coli. Responses were dose-dependent and reproducible for each endotoxin in five strains of mice.
3. Tolerance to endotoxin could be induced in mice by injection of doses of 500 ng but was not seen with doses of &lt;5 ng, even after repeated treatment.
4. Dinitrophenol, a metabolic inhibitor, and amphetamine, a metabolic enhancer, did not affect plasma zinc levels, indicating that changes in basal metabolic rate do not affect the outcome of this assay. The effects of pyrogenic materials other than endotoxin on plasma zinc levels were also tested and the results suggest that measurement of hypozincaemia in mice provides the basis for a simple, practical and inexpensive test for endotoxins and other pyrogens.
Hypoglycaemia, Hypothermia and Shivering in Man
Authors: Gale E. A. M. , Bennett T. , Green J. Hilary , MacDonald I. A. 
Published: August 2015

1. The present experiments were designed to elucidate the reasons for the fall in central body temperature during hypoglycaemia.
2. The first experiment was carried out at a room temperature of 25 °C on 11 male subjects. Hypoglycaemia was induced by infusion of insulin. Heat production (calculated from respiratory gas exchange) rose from a baseline of 5.10 ± 0.13 kJ/min (mean ± sem) to a peak of 6.25 ± 0.21 kJ/min (P &lt; 0.001), but core temperature fell concurrently by 0.51 ± 0.08°C and skin temperature fell by 1.1 ± 0.2°C. The net heat loss was due to peripheral vasodilatation and sweating.
3. To determine the effect of insulin-induced hypoglycaemia on thermoregulation in a cool environment, the experiment was repeated at a room temperature of 18–19°C on five of the subjects who had air blown over them until shivering was sustained. During this time heat production rose to 10.13 ± 1.67 kJ/min, but core temperature remained constant. Shivering stopped as plasma glucose fell below 2.5 mmol/l during insulin infusion and the subjects said they no longer felt cold.
4. During hypoglycaemia in the cold peripheral vasodilatation and sweating occurred, skin temperature fell by up to 0.8°C and core temperature fell below 35°C, so subjects had to be rewarmed.
5. Recovery of plasma glucose after hypoglycaemia in the cold was impaired at low body temperatures, but shivering was restored within seconds when glucose was given intravenously.
Mechanical Properties and Reactivity of Vessels in Isolated Perfused Lungs of Chronically Hypoxic Rats
Authors: Emery Celia J. , Bee Denise , Barer Gwenda R. 
Published: August 2015

1. Chronically hypoxic rats kept in 10% (v/v) O2 for 3–6 weeks, were compared with littermate control rats. Pulmonary vascular resistance, measured from the slope of the pressure-flow relationship in isolated lungs perfused with blood of normal packed cell volume was higher in chronically hypoxic than control rats even during normoxia.
2. Chronically hypoxic rats weighed less than control rats but their pulmonary vascular volume, measured with labelled albumin was similar to control rats. This, together with evidence that the number of precapillary vessels is not reduced, does not suggest a large reduction in the vascular bed in chronic hypoxia.
3. A greater vasodilator action of isoprenaline and adenosine in chronically hypoxic than control lungs suggested a higher normoxic vascular tone. This higher tone was not the sole cause of increased resistance in chronically hypoxic lungs, since maximal vasodilatation did not reduce resistance to control levels. The chief cause was probably encroachment of new muscle on the vascular lumen of small vessels.
4. Pulmonary arterial compliance was reduced in chronically hypoxic lungs.
5. Reactivity of vessels to ventilation hypoxia, over a wide range of oxygen tension, to angiotensin II (ANG II) and to adenosine 5′-triphosphate (ATP) was significantly greater in chronically hypoxic than control lungs, but thresholds to these stimuli were not reduced.
Novel Double-Isotope Technique for Enzymatic Assay of Catecholamines, Permitting High Precision, Sensitivity and Plasma Sample Capacity
Authors: Brown M. J. , Jenner D. A. 
Published: August 2015

1. A novel use of a double-isotope method is described which allows radioenzymatic assays to combine precision and sensitivity.
2. In the catechol O-methyltransferase assay separate portions of each plasma sample are incubated with either S-[3H]- or S-[14C]-adenosyl-l-methionine. Standards of noradrenaline and adrenaline are added to the latter portions and are thus converted into standards of [14C]metadrenalines. These are added to the 3H-labelled portions after the incubation, where they function as tracers.
3. The final recovery of 14C radioactivity corrects for (a) the efficiency of methylation in the plasma sample concerned and (b) the recovery of metadrenalines during the extraction procedures.
4. The 3H/14C ratio is constant in each assay for a given catecholamine concentration and is determined for samples to which standards of noradrenaline and adrenaline are added to the 3H- (as well as the I4C-) labelled portions before the initial incubation.
5. The sensitivity of the assay is increased by using high specific radioactivity S-[3H]adenosyl-l-methionine (60-85 Ci/mmol), and low backgrounds are maintained by catecholamine depletion in vivo in the rats used for enzyme preparation.
6. Both catecholamines (1.5 pg/ml; 10 pmol/l) may be detected; the coefficients of variation are 3.0 and 3.2% for noradrenaline and adrenaline respectively (intra-assay) and 4.6 and 5.0% (inter-assay).
Renal Salt and Water Handling in Water Immersion in the Nephrotic Syndrome
Authors: Berlyne G. M. , Sutton J. , Brown C. , Feinroth M. V. , Feinroth M. , Adler A. J. , Friedman E. A. 
Published: August 2015

1. Eleven nephrotic patients were immersed up to the neck in 1.3 m of water at 34°C for 4 h.
2. A diuresis began, within the first hour of, and continued throughout, immersion. The urine osmolality fell significantly and decreased to hypotonic levels in the first hour of immersion and increased gradually during the remainder of immersion and postimmersion.
3. Throughout immersion there was a steady increase in urinary sodium and chloride excretion and a sharp fall in the postimmersion hour.
4. Overall fractional excretion of sodium and of chloride increased steadily throughout immersion and fell during the post-immersion hour.
5. There was an increase in urinary potassium excretion on immersion but no change in fractional excretion of potassium. There was an initial increase in distally reabsorbed sodium/chloride on immersion, as expressed by positive values of CH2O in the first hour of immersion.
6. Plasma aldosterone levels were initially elevated in only two out of nine patients. There was a significant fall in plasma aldosterone levels on immersion, but there was no correlation between sodium/chloride handling and aldosterone levels on immersion.
Effects of Thyroparathyroidectomy, Phosphate Depletion and Diphosphonate Therapy on Acute Uraemic Extra-Osseous Calcification in the Rat
Authors: Ibels L. S. , Alfrey A. C. 
Published: August 2015

1. The effects of acute uraemia on arterial and visceral calcium concentrations were studied in acutely uraemic rats. The influences of thyroparathyroidectomy, phosphate depletion and diphosphonate therapy on extra-osseous calcium concentrations were assessed in this model.
2. Aortic and visceral calcium concentrations were greater in acutely uraemic rats than in non-uraemic rats. Both prior thyroparathyroidectomy and prior phosphate-depletion resulted in lower aortic and visceral calcium concentrations in non-uraemic rats and prevented the increase in aortic and visceral calcium concentrations with acute uraemia. Diphosphonate given for 5 days before and for 2 days after the induction of acute uraemia resulted in lower tissue calcium concentrations than in non-diphosphonate-treated acutely uraemic rats. In contrast, diphosphonate given only immediately before or only after induction of acute uraemia did not prevent the increase in extra-osseous calcium concentrations with acute uraemia.
3. It is concluded that acute uraemia results in an increase in arterial and visceral calcium concentrations. Both thyroparathyroidectomy and phosphate depletion are effective in preventing the increase in extra-osseous calcium concentrations in acute uraemia. Diphosphonates may have a future role in preventing such calcification.
Body Fluid Volumes in the Spontaneously Hypertensive Rat
Authors: Bianchi M. , Bellini G. , Hessan H. , Kim K. E. , Swartz C. , Fernandes M. 
Published: August 2015

1. Plasma volume, packed cell volume (PCV), blood volume, extracellular fluid volume (ECFV) and Evans blue disappearance rate were measured in conscious spontaneously hypertensive rats and in weight-matched Wistar normotensive rats.
2. Over the weight range studied (250-350 g), plasma and blood volumes were significantly lower in the spontaneously hypertensive rat. Extracellular fluid volumes were similar in the two groups. PCV arid Evans blue disappearance rates were significantly higher in the spontaneously hypertensive rat.
3. Negative correlations were obtained between plasma volume and mean arterial pressure and between the plasma/interstitial fluid volume ratio and mean arterial pressure.
4. the normal extracellular fluid volume and the lack of correlation with mean arterial pressure excludes volume expansion as a pressor mechanism during the established phase of hypertension in the spontaneously hypertensive rat.
Respiratory Arterial PH and P
co2 Oscillations in Patients with Chronic Obstructive Airways Disease
Authors: Cochrane G. M. , Prior J. G. , Wolff C. B. 
Published: August 2015

1. Arterial pH oscillations have been monitored in vivo in patients with well defined chronic obstructive bronchitis, asthma and clinical emphysema.
2. the patients with clinical emphysema were shown to differ from those with chronic obstructive bronchitis on the basis of a number of clinical and physiological criteria.
3. Patients with asthma showed least attenuation of their pH oscillations as a group, in contrast to emphysematous patients who showed most attenuation. in patients with clinical emphysema the attenuation was relatively homogeneous. the patients with chronic obstructive bronchitis showed the full range from normal oscillations (zero attenuation) to zero (complete attenuation).
4. the amplitude and approximate rate of change of upslope of the Paco2 oscillations in vivo were calculated, from measured pH oscillation amplitudes, using buffer slope values in vitro from Siggaard Anderson [(1962, 1963) Scandinavian Journal of Clinical and Laboratory Investigation, 14, 598–604; 15, 211–217], then dividing the Paco2 amplitude by half the respiratory period.
5. Mean arterial Pco2in vitro showed a very strong correlation with the downslope of the pH oscillation in vivo (calculated as for Paco2 upslope) in patients without clinical emphysema. This correlation would be expected to some extent, owing to the logarithmic relationship of Paco2 oscillations to pH oscillations. However, the mean arterial Pco2 also showed a very strong correlation with the upslope of the calculated Paco2 oscillations, again excluding patients with clinical emphysema.
Blood Pressure and Plasma Sodium and Potassium
Authors: Bulpitt C. J. , Shipley M. J. , Semmence A. 
Published: August 2015

1. Two thousand, three hundred and twenty-eight men and 1496 women between the ages of 35 and 64 years were screened for hypertension and their plasma sodium and potassium concentrations measured. Those on antihypertensive or diuretic treatment were excluded from further analysis.
2. After adjusting for age, body mass index and other variables, plasma potassium was negatively associated with both systolic and diastolic pressure in men and women. A decrease in plasma potassium of 1 mmol/l was associated with an increase in systolic pressure in women of 7 mmHg (P &lt; 0.001) and diastolic pressure of 4 mmHg (P &lt; 0.001). In men the corresponding increases were 4 mmHg (P &lt; 0.01) and 2 mmHg (P &lt; 0.05).
3. After adjusting for the other variables as above, plasma sodium was positively related to systolic blood pressure but not to diastolic pressure. An increase in plasma sodium of 1 mmol/l was associated with an increase in systolic pressure of 1 mmHg in both men (P &lt; 0.01) and women (P &lt; 0.05).
Factors Influencing Cardiac Hypertrophy in Hypertensive Patients
Authors: Ibrahim M. Mohsen , Madkour M. Aziz , Mossallam Ragaa 
Published: August 2015

1. Seventeen male patients with essential hypertension were studied after 4 weeks of placebo and after 8 weeks of β-adrenoceptor-blockade therapy with atenolol (100 mg/day).
2. The influence of the following factors on left ventricular wall thickness and left ventricular mass index as determined by echocardiography was examined: patient's age, duration of hypertension, arterial pressure, blood pressure variability, supine heart rate, maximal exercise heart rate, left ventricular wall stress and 24 h urinary catecholamines.
3. Left ventricular mass index was related to systolic blood pressure (r = 0.54, P &lt; 0.05) and to extent of increase in heart rate with maximal exercise (r = 0.62, P &lt; 0.05). No significant correlation was present between mass index and other variables.
4. After atenolol therapy, left ventricular mass index decreased by 14 g/m2 (12%). Changes in mass were related to its initial value (r = 0.69, P &lt; 0.01) and to% change in wall stress (r = 0.64, P &lt; 0.05). Patients who had a decrease in mass index of 10% or greater had an initially lower diastolic pressure (P &lt; 0.001). Other factors did not appear to influence significantly the regression of hypertensive left ventricular hypertrophy.
Haemodynamic Changes after Surgical Reversal of Chronic Two-Kidney, One-Clip Hypertension in the Rat
Authors: Russell G. I. , Brice J. M. , Bing R. F. , Swales J. D. , Thurston H. 
Published: August 2015

1. Within 24 h of surgical reversal of chronic Goldblatt two-kidney, one-clip hypertension in the rat, of &gt;4 months duration, blood pressure had fallen to normal levels. At this time there was no difference between the effects of removal of the clip or the ischaemic kidney but, at 60 days after reversal, the blood pressure of rats which had been nephrectomized was significantly higher than that of normal controls.
2. The fall in blood pressure was associated with a fall in total peripheral resistance to normal by 24 h despite the previous established fact that structural vascular changes take much longer to reverse. There was a corresponding rise in cardiac output, mainly due to an increase in stroke volume. Nephrectomized rats had a significantly higher stroke volume compared with those unclipped 24 h after operation.
3. As blood pressure can become normal in the presence of structural cardiovascular change by a fall in total peripheral resistance it would seem unlikely that resistance vessel hypertrophy is responsible for the maintenance of blood pressure in this model. Another peripherally acting mechanism therefore has to be postulated.
Plasma Noradrenaline as a Measure of Baroreflex Sensitivity in Hypertensive Man
Authors: Shepherd A. M. M. , Lin M.-S. , Keeton T. K. , McNay J. L. 
Published: August 2015

1. Changes in plasma noradrenaline levels and heart rate were used as measures of baroreflex sensitivity in six hypertensive subjects given serial incremental doses of sodium nitroprusside (intravenously) to lower blood pressure.
2. The rises in both heart rate and plasma noradrenaline concentration were linearly related to the decrement in blood pressure and inversely related to the severity of the hypertension.
3. A positive correlation between rise in heart rate and rise in plasma noradrenaline was found for each subject. With increasing severity of hypertension, a greater increase in heart rate occurred for each increment in plasma noradrenaline concentration.
4. Baroreflex sensitivity can be assessed by relating changes in heart rate to change in arterial pressure; however, this method does not distinguish the relative contributions of the vagal and sympathetic components of the autonomic neural response or variations in the chronotropic response to sympathetic stimulation.
5. Changes in plasma noradrenaline levels in response to graded reductions in blood pressure may be a more appropriate measure of baroreflex sensitivity than the methods currently used in clinical investigation.
A Sympathetic Hypertensive Reflex from the Heart of Conscious Dogs
Authors: Pagani M. , Pizzinelli P. , Furlan R. , Guzzetti S. , Rimoldi O. , Malliani A. 
Published: August 2015

1. The aim of the present experiments was to study in conscious animals the effect of chemical stimulation of cardiac sensory innervation by bradykinin, a physiological substance known to activate both vagal and sympathetic cardiac sensory nerve endings, at doses devoid of systemic haemodynamic effects.
2. In conscious dogs with implanted catheters bradykinin (100 ng/kg) injected into a cannulated branch of the left coronary artery induced significant (P &lt; 0.01, n = 5) reflex increases in mean arterial pressure and heart rate as well as increases in left ventricular pressure, left ventricular dP/dt max. and coronary blood flow.
3. These changes were obtained in the absence of pain reactions.
4. The concept, derived from experiments on anaesthetized animals, that chemical stimulation of the intact sensory supply of the heart always elicits a cardiovascular depressor reflex mediated by cardiac vagal afferents has to be modified, as pressor sympathetic reflexes may occur after an appropriate stimulus to the fully innervated heart of conscious dogs.
Adrenergic Components of Hypertension after Renal Transplantation
Authors: Smith R. S. , Reid J. L. , Warren D. J. 
Published: August 2015

1. Blood volume, total exchangeable sodium and the effects of head-up tilt on plasma noradrenaline were studied in 10 normotensive and 11 hypertensive renal transplant recipients. The blood pressure and heart rate responses to infused noradrenaline and isoprenaline were measured.
2. Blood volume and total exchangeable sodium were significantly greater in hypertensive than in normotensive patients.
3. Resting plasma noradrenaline was significantly higher in both groups of transplantees than in normal subjects, but was similar in normotensive and hypertensive patients.
4. Plasma noradrenaline rose in normotensive but not hypertensive patients in response to head-up tilt.
5. The rise in blood pressure in response to infused noradrenaline was significantly greater in hypertensive than in normotensive transplantees. Both groups of patients showed similar responses to infused isoprenaline.
6. Extracellular fluid volume expansion associated with increased α-receptor sensitivity to noradrenaline may contribute to hypertension in renal transplant recipients.
Blood Pressure, Renal and Metabolic Effects of ACTH in Normotensive Man
Authors: Whitworth Judith A. , Saines Dianne , Thatcher Robyn , Butkus Aldona , Scoggins B. A. , Coghlan J. P. 
Published: August 2015

1. The blood pressure, renal and metabolic effects of adrenocorticotropic hormone (ACTH) have been studied in six normotensive subjects and two patients with Addison's disease on maintenance steroid therapy.
2. In normotensive subjects, 5 days ACTH treatment (0.5 mg 12 hourly) was associated with a rise in systolic blood pressure and mean arterial pressure. There was a small rise in diastolic pressure but no consistent change in heart rate. Plasma sodium increased and plasma potassium fell. Serum creatinine and urea concentrations were unchanged. Fluid intake increased and urine output was unchanged but ACTH withdrawal was associated with a diuresis. There was an initial reduction in urinary sodium excretion and a natriuresis after ACTH withdrawal. Plasma volume and body weight rose.
3. ACTH produced increases in plasma cortisol, 11-deoxycortisol, corticosterone, deoxycorticosterone, aldosterone, 17α-hydroxyprogesterone and 17α,20α-dihydroxyprogesterone. Plasma renin concentration fell.
4. Patients with Addison's disease showed no change in blood pressure or in any other metabolic variable studied.
5. The effects of ACTH in man resembled those found in sheep.
Hypertension, Cerebrovascular Disease and Stomach Cancer: Is the Salt Hypothesis True?
Authors: Whelton Paul K. , Goldblatt Peter 
Published: August 2015

1. Analysis of age-adjusted death rates from 21 countries over a 20-year period identified the presence of a strong positive association between recorded mortality from stroke, hypertension and stomach cancer. However, the slopes of regression lines for secular trends analyses varied considerably from country to country, suggesting an inconsistency in the pattern of the relationship.
2. A death certificate study of diagnostic concordance correctly identified previously known disease associations but failed to recognise any special relationship between stroke and stomach cancer or hypertension and stomach cancer.
3. Our results fail to confirm the presence of a unique relationship between stroke and stomach cancer. On the basis of these observations, the hypothesis that exposure to salt increases an individual's risk of developing both stroke and stomach cancer seems unlikely.