bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of pH on Folic Acid Absorption in Man
Authors: MacKenzie J. F. , Russell R. I. 
Published: August 2015

1. Pteroylmonoglutamic acid (PteGlu) absorption has been measured by using the technique of small-intestinal perfusion with tritiated PteGlu in normal subjects and in patients with coeliac disease.
2. At similar intrajejunal pH, patients with untreated coeliac disease have significantly less PteGlu than normal subjects and patients with treated coeliac disease.
3. The ‘resting’ pH in the jejunum did not differ markedly between normal subjects and patients with coeliac disease.
4. Increasing pH decreased PteGlu absorption in patients with coeliac disease and in normal subjects.
5. These findings suggest that PteGlu malabsorption in coeliac disease is not due to abnormally high pH in the jejunum.
Elimination of Cholesterol in Hyperlipoproteinaemia
Authors: Angelin B. , Einarsson K. , Hellström K. , Kallner M. 
Published: August 2015

1. Cholesterol intake (about 0·25 mmol/day) and the faecal excretion of cholesterol, coprostanol and coprostanone were determined in normolipidaemic control subjects and hyperlipidaemic patients, whose bile acid kinetics had been previously studied.
2. The combined excretion of the neutral steroids (excluding plant sterol and plant sterol metabolites) averaged 1·07 ± 0·13 (± sem) mmol/day in the control subjects (n = 14). The corresponding values in patients with hyperlipoproteinaemia type IIa (n = 19), II (n = 12) and IV (n = 23) were 0·86 ± 0·10, 0·93 ± 0·11 and 1·48 ± 0·17 mmol/day respectively.
3. The mean values for the net steroid ‘balance’, defined as the combined amount of bile acid synthesized (determined by an isotope-dilution technique) and the faecal excretion of neutral steroids minus cholesterol intake, were 1·83 ± 0·22 mmol/day in the control subjects and 1·60 ± 0·15, 1·81 ± 0·19 and 3·53 ± 0·23 mmol/day in patients with type IIa, IIb and IV lipoprotein patterns respectively.
4. No significant correlations between net steroid ‘balance’ and sex, age, serum lipid concentrations, body weight or body surface area were found in any of the groups of subjects.
5. It is concluded that patients with type II hyperlipoproteinaemia eliminate cholesterol as bile acids and neutral faecal steroids normally. The type IV lipoprotein pattern is associated with increased bile acid synthesis and/or elevated faecal excretion of neutral steroids, so that the net steroid ‘balance’ is usually above the normal limit.
Changes in Cardiac and Hepatic Glucocorticoid Receptors after Adrenalectomy
Authors: Gregory M. C. , Duval D. , Meyer P. 
Published: August 2015

1. The total number of specific dexamethasone-binding sites in rat heart and liver cytosol was measured at intervals after adrenalectomy.
2. Between 12 and 48 h after adrenalectomy there was a significant increase in the number of binding sites in both heart and liver cytosol. Affinity was unchanged.
3. Of the [3H]corticosterone bound to liver cytosol proteins after an intravenous injection 98% disappeared within 2 h in vivo. Dissociation of endogenous corticosterone-receptor complexes in liver cytosol will thus be substantially complete some hours before the number of receptors increases.
4. It was concluded that there is a true increase in the number of glucocorticoid receptors occurring principally between 12 and 48 h after suppression of endogenous steroids.
Evidence for Peripheral Vascular Involvement in Mild Elevation of Blood Pressure in Man
Authors: Sivertsson R. , Sannerstedt R. , Lundgren Y. 
Published: August 2015

1. Cardiac output at rest, intra-arterial blood pressure and hand blood flow at maximal vasodilatation were studied in two groups of 18–25-year-old men: forty-four with mild blood pressure elevation were referred from a military enlistment centre, and twenty-nine normotensive volunteers were mainly recruited from the same enlistment centre.
2. The study group was characterized by a significantly higher cardiac index at rest, and a significantly higher blood flow resistance in the hand at maximal vasodilatation than the control group, indicating the presence of structural modifications in the resistance vessels of patients with mild blood pressure elevation.
3. The tendency to increased vascular resistance in the blood vessels of the hand at maximal vasodilatation was more pronounced in patients with a normal cardiac index than in those with a high index. This suggests inclusion in the study group of tense, anxious individuals with an elevated cardiac index but otherwise normal circulation, but does not exclude the possibility that these patients may develop structural changes later on.
The Intrarenal Release of Renin in the Rat
Authors: Morgan T. O. , Davis J. , Gillies A. 
Published: August 2015

1. A technique was developed to measure renin concentration in nanolitre volumes of blood.
2. The renin concentration in renal venous blood was higher than in renal arterial blood.
3. The renin concentration in blood from the efferent arteriole was less than in blood from the renal artery and renal vein.
4. Renin enters the circulation distal to the efferent arteriole.
5. The release of renin into the interstitium would allow local formation of angiotensin and the system could act as an intrarenal control mechanism.
Role of the Renal Nerves in Renin Release during Suprarenal Aortic Stenosis in Cats
Authors: Stella A. , Calaresu F. , Zanchetti A. 
Published: August 2015

1. Renin release from an intact, innervated kidney and from the contralateral denervated kidney was measured before and during a period of suprarenal aortic stenosis.
2. Aortic stenosis of 10 min duration reduced renal perfusion pressure to 50 mmHg and increased renin release from both kidneys, but the response from the innervated kidney was greater.
3. A study of the time-course of the response during 30 min of aortic stenosis showed that the difference in rate of renin release between the innervated and the denervated kidney is greatest during the first few minutes of aortic stenosis.
Stimulation of Renin Secretion by Frusemide and Diazoxide in the Isolated Rat Kidney
Authors: Vandongen R. , Greenwood Dianne M. 
Published: August 2015

1. The effect of diazoxide (17·3 μmol min—1 g—1) and frusemide (0·12 μmol min—1 g—1) on renin secretion was examined in the isolated perfused rat kidney. These substances are potential renal vasodilators with opposite effects on urine sodium excretion.
2. Both agents significantly increased renin secretion rate above control values. In the case of frusemide this was not altered by ureteric occlusion and presumed absence of urine flow.
3. Mean renal perfusion pressure decreased to the same extent with diazoxide and frusemide infusion as in the control experiments and no additional vasodilatory effect was observed on the basis of changes in flow rate of perfusate.
4. These observations identify an intrarenal site of action for diazoxide and frusemide on renin secretion. The apparent independence of this stimulatory action on renal vasodilatation and urine flow suggests a direct effect on the renin-producing cell.
Exchangeable Sodium in Experimental Hypertension in Rats
Authors: Doyle A. E. , Duffy S. , MacDonald G. J. 
Published: August 2015

1. Total exchangeable sodium was measured in rats by a radio-sodium equilibration method, before and after the production of hypertension by clipping the left renal artery, with or without contralateral nephrectomy.
2. Clipping of one renal artery with removal of the other kidney produced severe hypertension with no significant changes in exchangeable sodium or plasma renin levels.
3. Clipping of one renal artery without contralateral nephrectomy produced severe hypertension in some animals, but little change in blood pressure in others. The animals which developed severe hypertension had a marked increase in exchangeable sodium with a concomitant rise in plasma renin; the animals with smaller rises in blood pressure did not have these changes.
4. The fact that both plasma renin levels and exchangeable sodium levels increase according to this method, suggests that hypertension in the two-kidney model is renin-dependent.
Studies on the Effect of Angiotensin II and of Des1-angiotensin II on Blood Pressure, Plasma Renin Activity and Plasma Aldosterone in the Dog
Authors: Beckerhoff R. , Uhlschmid G. , Vetter W. , Siegenthaler W. 
Published: August 2015

1. The effects of infusions of equimolar doses of angiotensin II (AII) and of Des1-angiotensin II (heptapeptide) on plasma renin activity, blood pressure and plasma aldosterone were compared in normal anaesthetized dexamethasone-suppressed dogs.
2. Plasma renin activity was equally suppressed by both compounds. The increase in blood pressure induced by the heptapeptide averaged 43–62% of the increase during AII infusions. No significant differences in aldosterone increase were observed between AII and the heptapeptide. Plasma aldosterone, however, dropped significantly faster in heptapeptide-treated dogs after the end of the infusions.
3. Sar1-Ala8-angiotensin II (saralasin, 400 pmol min—1 kg—1) suppressed plasma aldosterone that was stimulated by heptapeptide (20 pmol min—1 kg—1) completely. The same angiotensin antagonist had only a moderate effect on plasma aldosterone stimulated by AII. After stopping the antagonist infusion, plasma aldosterone rose significantly higher in dogs infused with AII than in those receiving the heptapeptide.
4. The results demonstrate differences between the effects of AII and the heptapeptide both on blood pressure and on plasma aldosterone. They do not support the hypothesis that the heptapeptide may be the main mediator of aldosterone secretion.
Dissociation of Blood Angiotensin II and Plasma Renin Activity during Chronic Treatment in Essential Hypertension
Authors: Sambhi M. P. , Barrett J. D. , Eggena P. , Thananopavarn C. 
Published: August 2015

1. Plasma renin activity and circulating amounts of blood angiotensin II were measured in twenty-six patients with uncomplicated essential hypertension.
2. Measurements were made during a control period and at 1, 4, 9 and 14 weeks of diuretic treatment with metolazone or hydrochlorothiazide.
3. Linear regression analysis indicated a progressive change in the relation of plasma renin activity and blood angiotensin II.
4. During chronic diuretic therapy (beyond 14 weeks) blood angiotensin II had stabilized to low and relatively fixed values across a wide range of plasma renin activities.
The Role of Vascular Capacitance in the Genesis of Essential Hypertension
Authors: Ulrych M. 
Published: August 2015

1. Analysis of relationships between blood volume, vascular capacitance, cardiopulmonary and peripheral blood volumes, labelled albumin disappearance rate, plasma renin activity, blood pressure and age was performed in essential hypertensive males.
2. The results indicate that capacitance bed constriction probably occurs with age in essential hypertension leading to an increase in the product blood volume × vascular capacitance tone even in the presence of low blood volume.
3. A metabolic defect in the venous vascular bed along with an abnormality of regulation of renal sodium excretion is postulated.
The Effect of Intravenous Angiotensin II on the Peripheral Circulation with Particular Reference to its Bearing on General Haemodynamics
Authors: Cachovan M. , Brod J. , Bahlmann J. , Sippel R. , Celsen B. , Hundeshagen H. 
Published: August 2015

1. Central and peripheral haemodynamic effects of intravenous infusion of angiotensin II have been investigated in ten normotensive subjects. Angiotensin II was given at the rate of 0·12–5·0 μg/min.
2. The pressor response to angiotensin II was accompanied by a significant increase in the total peripheral resistance, central venous pressure and by a marked reduction of the intravascular forearm volume and venous distensibility. Forearm circulation time was shortened.
3. Cardiac index, heart rate, forearm vascular resistance and the forearm blood flow did not change significantly in the whole group but in the individual subjects some of the variables changed markedly in either direction.
4. Direct action of angiotensin II on the vessels and its central and peripheral sympathomimetic action as well as the role of the baroreflex as responsible causes for haemodynamic changes after angiotensin II are discussed.
Vascular Actions of Frusemide and Bumetanide on the Rat Superior Mesenteric Vascular Bed: Interactions with Prostaglandins
Authors: Horrobin D. F. , Manku M. S. , Mtabaji J. P. 
Published: August 2015

1. The addition of frusemide or bumetanide to perfusion fluid inhibited the response of the isolated mesenteric vascular bed to noradrenaline.
2. Addition of prostaglandin E2 to the perfusion fluid completely restored the response to noradrenaline.
3. Inhibition of prostaglandin secretion by indomethacin with restoration of responses to noradrenaline by the addition of exogenous prostaglandin E2 prevented the inhibitory effect of frusemide or bumetanide on responses to noradrenaline.
4. The inhibitory effects of diuretics on responsiveness to noradrenaline is mediated by blockade of endogenous prostaglandin synthesis.
Isolation of Renal Membranes that Contain Kallikrein, Angiotensin I-Converting Enzyme (Kininase II) and Angiotensinase in the Rat
Authors: Ward P. E. , Erdös E. G. , Gedney C. D. , Dowben R. M. , Reynolds R. C. 
Published: August 2015

1. Fractions highly enriched in plasma membrane, endoplasmic reticulum or brush border were prepared from rat kidney cortex. Kallikrein was concentrated in the plasma membrane fraction, but not in the brush border fraction. Angiotensin I-converting enzyme (kininase II) and angiotensinase were localized in the brush border membrane.
2. It is suggested that kallikrein in the urine may originate from plasma membrane distal to the brush border of proximal tubules and the conversion of angiotensin I and the inactivation of bradykinin and angiotensin II may occur on the lumen membrane of the proximal tubular cells.
Role of Steroids in Hypertension: Evaluation of Plasma Mineralocorticoid Activity with Aldosterone Receptors
Authors: Baxter J. D. , Schambelan M. , Matulich D. T. , Spindler B. J. , Bartter F. C. 
Published: August 2015

1. A competitive ‘mineralocorticoid’ receptor-binding technique has been used to study plasma ‘mineralocorticoid’ activity in normal and hypertensive states. The binding reaction mixture contains the competitor steroids in undiluted plasma, [3H]aldosterone and rat kidney slices. Thus plasma binding and receptor occupancy can be simultaneously considered.
2. Competitor activities relative to that of aldoterone (100%) were: deoxycorticosterone (DOC), 16%; Cortisol, 0·4%; 18-hydroxydeoxycorticosterone (18-OH-DOC), 0·1%; 16β-OH-dehydroepiandrosterone and 16-oxo-androstenediol, inactive. (Binding characteristics for aldosterone and the other steroids tested with the rat receptor were found to be similar to those with receptors in slices from human kidney, obtained at operation.) These steroids and the spironolactone SC14266 were less active in plasma than in buffer, suggesting that they bind significantly to plasma and that this reduces their capacity to occupy the receptors.
3. These competition data also suggest that at normal and even mildly elevated concentrations, Cortisol does, but DOC and 18-OH-DOC do not, contribute significantly to the plasma mineralocorticoid activity. Competitor activity in plasma samples taken at 12.00 hours from normal subjects (upright) was greater than that in those taken at 08.00 hours (supine). This physiological change, corresponding to an increase in aldosterone, was detected even though there was an associated decrease in plasma Cortisol. Competitor activity in plasma from patients with primary aldosteronism was markedly elevated as compared with that of normal subjects. However, an increase in plasma steroids which bind to the mineralocorticoid receptor was not detected in plasma from patients with ‘low-renin essential hypertension’.
SC 23992: Radioreceptor Assays for Therapeutic and Side Effects
Authors: Funder J. W. , Mercer J. , Hood J. 
Published: August 2015

1. A new spirolactone (SC 23992) has been assayed in vitro to determine its affinity for mineralo-corticoid and androgen receptors.
2. Although two to eight times as potent an anti-aldosterone agent as Aldactone in vivo, SC 23992 has only ∼10% the potency in vitro.
3. This discrepancy between potency in vivo and in vitro appears to be explained on radioreceptor assay of the principal metabolites of Aldactone and SC 23992.
4. SC 23992 may represent an antimineralocorticoid with less antiandrogen side effects.
Effect of Intraventricular Perfusion of Angiotensin II in Conscious Normal Rats and in Rats with Hereditary Hypothalamic Diabetes Insipidus
Authors: Hutchinson J. S. , Schelling P. , Möhring J. , Ganten D. 
Published: August 2015

1. Artificial cerebrospinal fluid was perfused through the cerebral ventricles of conscious rats. A basal secretion rate of 16 ± 3 × 10—15 mol of immunoreactive angiotensin 11/min was calculated for intact rats.
2. Most of the immunoreactive angiotensin II consisted probably of the heptapeptide or pentapeptide angiotensin II fragments.
3. The pressor responses to intraventricular perfusions of angiotensin II were normal in Long—Evans rats, virtually absent in rats homozygous for hereditary hypothalamic diabetes insipidus, irrespective of whether they were injected with vasopressin tannate or not, and intermediate in rats heterozygous for hypothalamic diabetes insipidus.
4. The results suggest that the pressor response to intraventricular angiotensin II is related to the release of vasopressin.
Reduction of the Hypotensive Effect of Clonidine and α-Methyldopa by Various Psychotropic Drugs
Authors: Van Zwieten P. A. 
Published: August 2015

1. In chloralose-anaesthetized cats the centrally induced hypotensive effect of clonidine, and in some cases α-methyldopa, was diminished by pretreatment with a variety of tricyclic antidepressants and neuroleptic agents.
2. The interaction is assumed to occur at the central α-adrenoreceptors. Clonidine or α-methylnoradrenaline (from α-methyldopa) are the agonists, and the aforementioned psychotropic drugs are the antagonists.
3. Psychotropic drugs which are not α-receptor blockers, like butyrophenone neuroleptics (pimozide and haloperidol) or benzodiazepine tranquillizers, do not significantly diminish the centrally induced hypotensive effect of clonidine.
Noradrenaline Sensitivity of an Isolated Perfused Artery: Effects of Normal and Hypertensive Plasma
Authors: Rosendorff C. , Bloom D. S. , Stein M. G. 
Published: August 2015

1. The noradrenaline sensitivity of the isolated perfused rabbit artery was studied, during perfusion with Krebs solution, normal plasma, hypertensive plasma and a low-density lipoprotein (LDL) extract of normal plasma.
2. There was no difference in noradrenaline sensitivity between arteries perfused with Krebs and normal plasma.
3. Both hypertensive plasma and LDL potentiated the noradrenaline-induced vasoconstriction.
4. This potentiation was associated with increases in both the intrinsic activity of the drug-receptor complex and the drug—receptor affinity.
5. There is a circulating factor in the plasma of hypertensive patients which sensitizes arteries to noradrenaline, and this factor may be LDL.
Clinical and Haemodynamic Study of a new Vasodilator Drug L6150 (3-[bis-(2-Hydroxyethyl)Amino]-6-Hydrazinopyridazine) in Man
Authors: Brod J. , Bahlmann J. , Cachovan M. , Dahlgrün H. , Pretschner P. , Futterová M. 
Published: August 2015

1. L6150 is a highly effective vasodilator which produces an acute reduction of blood pressure when administered intravenously.
2. This is due entirely to a decrease in total peripheral vascular resistance.
3. On oral administration it can effectively lower blood pressure in mild hypertension and is effective in combination with other hypotensive agents with different mechanisms of action.
Deoxyribonucleic Acid Repair Synthesis: A new Factor for Defining High Blood Pressure
Authors: Thulin T. , Pero R. W. , Bryngelsson C. , Mitelman F. , Nordén Å. , Scherstén B. 
Published: August 2015

1. The level of DNA repair synthesis has been compared in males diagnosed as having hypertension (diastolic blood pressure ≥ 100 mmHg), males with slightly elevated blood pressure (>95th percentile corrected for age) and males with normal or subnormal blood pressure (≤30th percentile corrected for age).
2. The hypertensive males and the males with elevated blood pressure could not be distinguished from each other with respect to the levels of chemically induced repair synthesis, but both were significantly increased over the induced repair synthesis values of individuals with normal or low blood pressure. Since it has been shown previously that lymphocytes with high repair synthesis values also have increased levels of both carcinogen-DNA binding and chromosomal aberrations (Nordén, Scherstén, Thulin, Pero, Bryngelsson & Mitelman, 1975), the biological significance of this variable appears to be of value in discriminating between normal and high blood pressure groups.
The Origin and Fate of Salivary Urea and Ammonia in Man
Authors: Kopstein J. , Wrong O. M. 
Published: August 2015

1. Saliva obtained from the parotid duct of normal and uraemic subjects had an average urea concentration of 86% of the plasma concentration whereas in mixed saliva obtained from the mouth the urea concentration was only 31% of the plasma concentration. Ammonia concentrations were low or unmeasurable in parotid saliva but varied between 0·6 and 26 mmol/kg in oral saliva, showing a positive correlation with the plasma urea concentration.
2. The urea in samples of mixed oral saliva incubated at 37°C disappeared by 290 min. Ammonia steadily increased during incubation; within the first 100 min, the increase could be largely accounted for by bacterial hydrolysis of urea, but later non-urea sources became relatively more important.
3. These findings suggest that the ammonia in mixed oral saliva is derived by bacterial hydrolysis of urea within the mouth. However, the concentration of ammonia plus urea nitrogen in oral saliva was only 76% of the urea nitrogen concentration of parotid saliva, which suggests that some ammonia is lost from the mouth by buccal absorption or by volatilization.
4. To assess the role of non-ionic diffusion of ammonia through the buccal mucosa, we studied the effect of pH on the disappearance of ammonia from buffered solutions retained in the mouth. Ammonia concentrations fell more rapidly at pH 9 than at pH 7, as also did those of hydrazine, a non-volatile analogue of ammonia which is known to be absorbed through other mucosae by non-ionic diffusion. These findings suggest that salivary ammonia is reabsorbed passively through the oral mucosa in the un-ionized phase.
Blood Pressure Control in End-Stage Renal Disease in Man: Indirect Evidence of a Complex Pathogenic Mechanism besides Renin or Blood Volume
Authors: Cannella G. , Castellani A. , Mioni G. , Usberti M. , Guerra U. , Albertini A. , Maiorca R. 
Published: August 2015

1. In twenty-three uraemic patients on regular dialysis, plasma renin activity and blood volume were measured before and after a single dialysis. Three groups were identified; the first had a low or normal plasma renin activity and a high or normal blood volume, the second had a high plasma renin activity and a low blood volume and the third had both variables above normal.
2. In spite of these differences, diastolic blood pressure before and after dialysis was the same in the three groups and multiple regression analyses failed to demonstrate any dependence of blood pressure on plasma renin activity, blood volume or body weight taken separately or together.
3. We conclude that other factors besides plasma renin activity and blood volume are important in maintaining arterial hypertension in terminal renal failure.