bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrolytes, Environment and Blood Pressure
Authors: Langford H. G. , Watson Robert L.
Published: August 2015

1. Studies to explain a significant socioeconomic and rural-urban blood pressure gradient found in central Mississippi are reported.

2. 24 h sodium excretion alone fails to explain the differences found, and fails to correlate with blood pressure.

3. A single 24 h determination of electrolyte excretion correlates modestly with the mean of 6 days' collection. Three days' collection and blood pressure determination is a reasonable compromise.

4. The urinary Na/Ca ratio is significantly higher in specimens from rural black girls compared with urban girls, and significantly higher in specimens from those with systolic pressure > 125 mmHg compared with those with < 105 mmHg pressure.

5. The urinary Na/K ratio of black girls was significantly higher than that of white girls of the same age, as was their blood pressure.

6. No correlation between blood pressure and urinary electrolytes could be found in black women aged between 35 and 45.
Sympathetic Activity in Peripheral Nerves of Normo- and Hypertensive Subjects
Authors: Wallin B. G. , Delius W. , Hagbarth K.-E.
Published: August 2015

1. In hypertensive patients the general pattern of spontaneously occurring sympathetic activity (SA) as well as the sympathetic responses to various manoeuvres are similar to those of the normotensive controls.

2. This suggests that the multi-unit SA recorded in muscle and skin nerves of hypertensive patients are made up of impulses from the same fibre populations as in normotensive subjects and that the outflow of these impulses is controlled by similar mechanisms in the two groups.

3. More quantitative evidence obtained under standardized external conditions is necessary before it can be decided whether there is an increased strength of the sympathetic outflow to the skin in hypertensive patients.
The Thymus of Spontaneously Hypertensive Rats: Light- and Electron-Microscopic Studies
Authors: Rojo-Ortega J. M. , Yeghiayan E. , Genest J.
Published: August 2015

1. The present investigation was undertaken to study the possibility that hypertensive vascular disease could be associated with changes in the morphology of the thymus.

2. Using light- and electron-microscopic techniques, the thymus of spontaneously hypertensive rats (SHR) with (1 year of age) and without (10 weeks of age) severe vascular lesions were compared with appropriate controls.

3. The thymus of SHR with severe hypertensive vascular disease showed: (a) marked hyperplasia and hypertrophy of the epithelial cells, with ultrastructural features of hypersecretory activity, and (b) in contrast to the paucity of plasma cells in the thymus of the control animals, the SHR had numerous plasma cells.

4. These observations may suggest the involvement of an autoimmunological mechanism in the development of the vascular lesions in SHR.
Hypotensive Effect of Oxprenolol in Mild Hypertension: A Co-Operative Controlled Study
Authors: Muiesan G. , Motolese M. , Colombi A.
Published: August 2015

1. In a multicentre double-blind study, oxprenolol (OX) hypotensive effect was investigated in 329 patients with mild to moderate hypertension.

2. A factorial experimental design with three factors was chosen: OX mg/day 0, 20, 40, 60, 80; dihydrazinophthalazine (DHZ) mg/day 0, 30; and hydrochlorothiazide (HCH) mg/day 0, 30. Each treatment was carried out for a period of 4 weeks after an adequate placebo period.

3. Independently of the association with DHZ and/or HCH, OX yielded a hypotensive effect linearly related to dose (P < 0.05) for systolic and diastolic pressure in the standing position, but only for diastolic pressure in the supine position.

4. The addition of DHZ and/or HCH to OX at 80 mg/day caused a significant increase in the final hypotensive effect.
The Effect of Practolol (‘Eraldin’) in the Long-Term Treatment of Severe and Moderate Hypertension
Authors: Fulton R. M. , Fulton E. Hilda , Green K. G.
Published: August 2015

1. The results of a clinical trial of practolol in sixty-one patients with moderate and severe hypertension are presented. Alone or with a diuretic the drug was highly effective in thirty patients, and in a further eight who developed side effects. Effectiveness was not directly related to dosage or blood levels of drug, or to the severity of the hypertension.

2. Nine non-responders to practolol were found to respond to propranolol which is probably a more widely effective antihypertensive agent. Nevertheless, the additional safety factors of practolol and twice daily dosing make it first choice for many patients. We have been impressed by the ability of both β-blocking drugs to control blood pressure without impairing the quality of every-day life.
Age-Dependent Changes of Plasma Renin Concentration in Humans
Authors: Hayduk K. , Krause D. K. , Kaufmann W. , Huenges R. , Schillmöller U. , Unbehaun V.
Published: August 2015

1. Plasma renin concentration (PRC) in newborns greatly exceeded PRC in children and adults. PRC in cord plasma of newborns was higher than peripheral venous PRC in their mothers. PRC in the newborns increased further in the first 48 h post partum and then gradually decreased.

2. The mean PRC of healthy children and adults on free sodium intake decreased with age by an exponential function.

3. The absolute increase of PRC in response to upright posture (PRCupright — PRCrecumbent) decreased with age. The relative increase of PRC in response to upright posture (PRCuprjght:PRCrecumbent) remained unchanged with age, the PRC in upright posture being about twice the basal PRC in all age groups.
Plasma Renin Activity and Plasma Renin Substrate in Hypertension Associated with Steroid Excess
Authors: Krakoff L. R. , Mendlowitz M.
Published: August 2015

1. Plasma renin activity and plasma renin substrate were measured by radioimmunoassay of generated angiotensin I in patients with steroid excess syndromes. Significant increases in substrate were observed in patients with Cushing's syndrome, during glucocorticoid therapy and on oral contraceptive agents. Suppression of plasma renin activity occurred only in primary aldosteronism.

2. The Michaelis constant (Km) for the reaction between renin and substrate in plasma at physiological pH (7.4) was also determined. The extent to which elevated plasma renin substrate increases the velocity of angiotensin I formation was then calculated.

3. In patients with Cushing's syndrome, glucocorticoid therapy or oral contraceptive use, elevated renin substrate coupled with failure of suppression of circulating renin results in increased angiotensin I formation.
The Effect of Chronic Sodium Loading and Sodium Restriction on Plasma and Renal Concentrations of Prostaglandin a in Normal Wistar and Spontaneously Hypertensive Aoki Rats
Authors: Zusman R. M. , Forman B. H. , Schneider G. , Caldwell B. V. , Speroff L. , Mulrow P. J.
Published: August 2015

1. In normal and hypertensive rats prostaglandin A (PGA) in plasma and kidney increased on low sodium intake and decreased on high sodium intake.

2. Plasma and renal concentrations of PGA were higher in spontaneously hypertensive rats than in normal Wistar rats in each dietary group.
The Effect of Fasting and Food on the Rate of Purine Biosynthesis DE NOVO in the Rat Spleen
Authors: Semple P. F. , Henderson A. R. , Boyle J. A.
Published: August 2015

1. The effect of an 18, 30 or 40 h fast on the rate of purine biosynthesis de novo as measured by the incorporation of [14C]formate into formylglycinamide ribonucleotide during azaserine block has been examined in the rat spleen.

2. There is a reproducible fall in the rate of purine biosynthesis de novo during fasting. Values at 40 h were approximately one-third of the values in the colony-fed non-fasted animals.

3. Re-feeding animals with an amino acid mixture by stomach tube partially reversed the inhibition of purine synthesis induced by a 40 h fast.
Relationship of Plasma Zinc to Human Hypertension
Authors: Thind Gurdarshan S. , Fischer Grace M.
Published: August 2015

1. Plasma zinc (μg/100 ml) was determined by atomic absorption spectrophotometry in ninety renal venous, inferior vena caval or peripheral venous specimens obtained from fifteen normal control subjects and thirty hypertensive patients, none of whom had renal failure.

2. Peripheral or central venous plasma zinc levels in ten patients with essential hypertension were not significantly different from those of control subjects. There were, however, significantly lower venous plasma zinc levels found in sixteen patients with renal artery stenosis and four patients with renal parenchymal disease.

3. The only clinical variable found to have a significant inverse correlation with plasma zinc was the mean arterial blood pressure.

4. There were no significant differences in zinc concentrations between central venous and renal venous plasma specimens.
Homoarginine in Cystinuria
Authors: Cox B. D. , Cameron J. S.
Published: August 2015

1. By using ion-exchange columns coupled to a sensitive automated Sakaguchi reaction, in addition to the normal ninhydrin reaction for amino acids, homoarginine, a guanidino homologue of arginine, was found in the plasma and urine of both normal and cystinuric individuals.

2. In all seven cystinuric subjects studied, urinary excretion of homoarginine was approximately ten times that found in normal subjects; the plasma levels of this amino acid were considerably reduced relative to normal individuals.

3. Homoarginine in the plasma can be derived either metabolically from lysine or from dietary sources.

4. In normal subjects homoarginine was cleared at a higher rate than arginine. On the other hand, the clearance of arginine exceeded that for homoarginine in the majority of cystinuric subjects although the values obtained for homoarginine indicate that the defect in amino acid transport also affects this amino acid.

5. The defect in the proximal tubular reabsorption of homoarginine is less severe than that for arginine, suggesting that the reabsorptive site for homoarginine may not be the same as that for arginine.

6. In the design of models for the tubular reabsorption of amino acids in health and disease, the presence of homoarginine and its excessive loss in cystinuria must be accounted for.
The Effect of Varying the Amount of Unlabelled 5,5-Dimethyloxazolidine-2,4-Dione(Dmo) in the Measurement of Rat Hepatic Intracellular pH Using [14C]DMO
Authors: Iles R. A. , Cohen R. D.
Published: August 2015

1. Hepatic intracellular pH (pHi) was measured in intact rats by distribution of 5,5-dimethyloxazolidine-2,4-dione (DMO), using [14C]DMO and a range of doses of unlabelled DMO, previously neutralized with sodium hydroxide.

2. Mean calculated pH; fell from 7·27 to 7·17 as the dose of added unlabelled DMO was increased from zero to 0·19 mmol/kg (25 mg/kg) and thereafter remained constant up to and including the highest dose group (1·55 mmol/kg; 200 mg/kg).

3. Control observations showed that the change in calculated pHi with DMO dose could have been related to the consequential sodium load, rather than to the presence of a saturable process determining the distribution of DMO.

4. Reasons are given why it is nevertheless desirable to add carrier DMO when employing [14C]DMO for the measurement of hepatic pHi in the rat.
Influence of Volume Expansion on Renal Diluting Capacity in the Rat
Authors: Martinez-Maldonado M. , Eknoyan G. , Suki W. N.
Published: August 2015

1. The functional capacity of Henle's loop was examined during hypotonic, isotonic and hypertonic extracellular fluid volume expansion. To eliminate a possible role of antidiuretic hormone (ADH) in the alteration of free water excretion, rats with congenital diabetes insipidus were used. The infusion of hypotonic saline resulted in a progressive rise in free water clearance (CH2O) throughout the range of urine flow (V) attained. Similar results were obtained in rats treated chronically with deoxycorticosterone acetate (DOCA). The infusion of isotonic saline (sodium chloride, 154 mmol/l) produced an initial rise in CH2O until V represented 10% of the filtered load, after which CH2O appeared to reach a plateau. The limitation of CH2O was more marked when hypertonic saline was infused. Medullary and papillary non-urea solute (NUS) concentration rose progressively with the increasing concentration of the saline solution infused.

2. The greater fractional sodium excretion (FENa) after acute isotonic and hypertonic volume expansion is probably the result of inhibition of sodium reabsorption in the collecting duct, although inhibition in the ascending limb cannot be entirely excluded. The depression of CH2O as a function of V seen during acute isotonic or hypertonic volume expansion can be attributed in part to enhanced water back-diffusion from the collecting duct consequent to the increasing medullary and papillary interstitial NUS concentration, even in the absence of ADH.

3. Chronic expansion of extracellular fluid volume by DOCA administration did not modify the response to hypotonic saline infusion.
Relations between Oxalic Acid, Calcium, Magnesium and Creatinine Excretion in Normal Men and Male Patients with Calcium Oxalate Kidney Stones
Authors: Hodgkinson A.
Published: August 2015

1. The daily excretion of oxalate, calcium, magnesium and creatinine was determined in fifty-two normal men and sixty-five male patients with calcium oxalate-containing renal stones.

2. Direct relationships were found between calcium and oxalate excretion, magnesium and oxalate excretion and calcium and magnesium excretion in both normal subjects and stone-formers. The significance of these relationships is discussed.

3. The mean excretion of calcium and oxalate was significantly higher in the stone-formers, compared with the controls, both calcium and oxalate excretion being raised by about 20%.

4. The effect of oral ingestion of glucose and casein on the rate of excretion of calcium, magnesium, oxalate and phosphate was examined. Glucose increased the rate of calcium and magnesium excretion but had no effect on oxalate excretion and suppressed phosphate excretion. Casein also increased calcium excretion but had little or no effect on magnesium or oxalate excretion, and it increased phosphate excretion.

5. The association of high calcium excretion with high oxalate excretion, in both normal subjects and stone-formers, results in a high degree of supersaturation of the urine with respect to calcium oxalate. The implication of these findings with respect to the cause and treatment of calcium oxalate stones is discussed.
Growth of the Heart and Lungs in Hypoxic Rodents: A Model of Human Hypoxic Disease
Authors: Hunter Carolin , Barer Gwenda R. , Shaw J. W. , Clegg E. J.
Published: August 2015

1. Rats and mice were kept in a decompression chamber at 52 kPa (390 mmHg) for 1–4 weeks and their hearts and lungs were compared with littermate control animals. In both species growth was retarded in the hypoxic environment.

2. In both species small peripheral lung vessels became thickened, developing two elastic laminae with a muscular coat between. A method was developed for assessing these changes in large numbers of animals. The number of thick-walled vessels was still high after 4 weeks' recovery in a normal environment. Pulmonary vascular resistance, measured by a perfusion method, increased in animals kept in the decompression chamber.

3. Mouse lungs became heavier than controls; the increase was not due to a greater fluid content. Rat lungs were heavy in relation to body weight but not heavier than controls; there may have been slight thickening of alveolar walls. Chest areas, measured from radiographs, were large relative to body weight in hypoxic rats.

4. The relationship between right and left ventricular weight and body weight was studied in normal rats and mice. The left ventricle grew about four times more quickly than the right. Changes in ventricular weights during exposure in the decompression chamber and subsequent recovery in a normal environment were related to these normal growth curves.

5. In both species the right ventricle grew abnormally fast in the decompression chamber. It was absolutely heavier than that of controls and relative to body weight was extremely heavy. After 4 weeks' recovery the relationship between right ventricular weight and body weight was nearly normal; this was achieved by retarded growth or actual loss of weight.

6. In mice the left ventricle grew normally in the decompression chamber and was heavy in relation to body weight. In rats its growth was retarded in the chamber and was normal in relation to body weight.

7. Morphometry of the hypertrophied right ventricle showed that muscle fibre size and total muscle mass had increased in hypoxic rats. There had been no increase in nuclear mass, but the perinuclear sarcoplasm had increased. All layers of the myocardium participated in the hypertrophy.
The Effects of Epidural Anaesthesia on the Pituitary—Adrenal Response to Surgery
Authors: Cosgrove D. O. , Jenkins J. S.
Published: August 2015

1. Plasma cortisols were measured in nine patients undergoing pelvic surgery under epidural anaesthesia.

2. Compared with response under general anaesthesia, the cortisol response was usually delayed and diminished, sometimes to an extreme degree.

3. No clinical problems were found to be associated with the very low cortisol levels, and the hypotension associated with epidural anaesthesia was neither related to the cortisol concentration nor corrected by glucocorticoid supplements.
Effect of Phenobarbitone Treatment on Vitamin D Metabolism in Mammals
Authors: Silver J. , Neale G. , Thompson G. R.
Published: August 2015

1. The metabolism of radioactive cholecalciferol was studied in control and phenobarbitone-treated rats and pigs.

2. Treatment with phenobarbitone enhanced the appearance in plasma of 25-hydroxycholecalciferol (peak IV on silicic acid chromatography), and of more-polar metabolites (peak V), but not of the most-polar metabolites (peak VI). Peak IV had the chromatographic properties of authentic 25-hydroxycholecalciferol (25-HCC) and had biological activity.

3. There was no effect on the appearance of peaks V and VI in plasma after an injection of radioactive 25-HCC.

4. Treatment with phenobarbitone enhanced the excretion of metabolites of radioactive vitamin D3 in bile. These metabolites were largely water-soluble conjugates of peaks IV, V and VI, which included glucuronides. Peak IV in bile was not identical with 25-HCC.

5. Prolonged treatment with phenobarbitone depleted the tissue radioactivity of rats given radioactive vitamin D3.
Total Body, Plasma and Erythrocyte Potassium and Leucocyte Ascorbic Acid in ‘Ultra-Fit’ Subjects
Authors: Boddy K. , Hume R. , King Priscilla C. , Weyers Elspeth , Rowan T.
Published: August 2015

1. Total body potassium was measured in professional football players before the football season began and at approximately mid-season. The values obtained were significantly higher than in healthy subjects taking only average exercise. There was a significant increase in body potassium as the season progressed.

2. Lean body mass was estimated by four methods and the results were compared. The values of lean body mass, as a percentage of body weight, were significantly higher than in healthy control subjects taking only average exercise and they also increased significantly over the period of the study.

3. The mean erythrocyte potassium concentration was lower pre-season than at mid-season and the pre-season value was also significantly less than in healthy controls. The values before and after vigorous exercise were not significantly different.

4. Conversely, the pre-season mean plasma potassium concentration was significantly higher than in control subjects and than the mid-season value. The mean plasma potassium concentration was higher before vigorous exercise than immediately afterwards.

5. The leucocyte count increased significantly after vigorous exercise, correlating with a decrease in leucocyte ascorbic acid content.
Isoenzyme Studies in the Identification of Transplanted Muscle in the Mouse
Authors: Neerunjun J. S. , Dubowitz V.
Published: August 2015

1. The isoenzyme pattern of phosphohexose isomerase on starch-gel electrophoresis was found to be significantly and consistently different in the muscles of the Swiss white and 129 ReJ mice. This provided a good marker for identifying donor and host muscle.

2. The isoenzyme pattern does not appear to be due to different proportions of type 1 and 2 fibres or to fibre type grouping as is found in denervated/reinnervated muscle.

3. Tibialis anterior muscles from Swiss white mice were transplanted into the legs of 129 ReJ mice and vice versa. Transplantations between mice of the same strain were used as controls.

4. The isoenzyme patterns from transplanted muscles indicate that it is the donor muscle which regenerates when the tissue is transplanted from one animal to another.
The Effects of Drugs that Cause Neutropenia upon Colony Formation by Bone Marrow Cells in Semi-Solid Agar
Authors: Howell A. , Chinn Susan , Andrews T. M. , Watts R. W. E.
Published: August 2015

1. The effect of drugs that cause neutropenia has been tested upon normal bone marrow colony formation in semi-solid agar.

2. Thiouracil, methimazole and phenylbutazone do not cause inhibition whereas sodium aurothiomalate, 6-mercaptopurine and chloramphenicol cause dose-related inhibition of colony formation at or below drug concentrations found in serum during therapy. Chloramphenicol also inhibits mouse bone marrow, L cells and Hela cells in agar culture.

3. Dose—response curves have been analysed by the probit method and found to be reproducible.
Air Embolism: Fission of Microbubbles upon Collision in Plasma
Authors: Hills B. A.
Published: August 2015

1. A phenomenon is described whereby microbubbles of 150–250 μm diameter have been observed to disintegrate upon collision in human plasma and surfactant solutions, into many smaller bubbles of diameter 35–45 μm.

2. The thermodynamic aspects are discussed together with the physiological implications in the occlusion of vessels, enhanced haemolytic effects of air and the supersaturation of blood.

3. Air is found to dissolve much more rapidly in the form of the ultramicrobubbles resulting from collision, their ‘life’ now becoming of an order of magnitude similar to the blood circulation time in man.

4. The possible protective role of this phenomenon in preventing vascular occlusion by air embolism is discussed.
Cation Content and Transport Characteristics of the Sickle-Cell Erythrocyte and their Relationship with Structural Changes in the Membrane
Authors: Kurantsin-Mills J. , Kudo M. , Addae S. Kojo
Published: August 2015

1. The intra-erythrocytic concentrations of sodium and potassium and the water content have been determined for haemoglobin (Hb) SS cells and negroid Hb AA cells.

2. The erythrocyte concentration of sodium was 40% higher and potassium 10% lower in the Hb SS than in the Hb AA cells. The cell water expressed as % weight of cell (corrected for trapped plasma) was identical for both cell types.

3. Normal Caucasian erythrocytes with Hb AA contained 40–50% less sodium but about the same potassium concentration as negroid Hb AA cells.

4. Potassium efflux into buffered iso-osmotic sucrose medium was much faster in Hb SS than in negroid Hb AA cells; ouabain-sensitive active sodium transport was twice as fast in the sickle-cell erythrocytes. Passive sodium efflux of erythrocytes suspended in a physiological medium was similarly faster in Hb SS cells.

5. Under the conditions of the experiments not less than 85% of the Hb SS erythrocytes appeared biconcave. Electron-microscopic examination of ultra-thin sections of Hb SS cells revealed marked discontinuities in the membrane. This suggests definite membrane alterations, which have probably resulted from the sickling-unsickling cycles occurring during the life-span of the cells.

6. It is suggested that the enhanced active sodium transport in the Hb SS erythrocyte is secondary to the augmented passive cation efflux, which in turn results from the leakiness of the erythrocyte membrane produced by the sickling-unsickling process.
The Renin-Angiotensin System in Acute Renal Failure in Rats
Authors: Matthews P. G. , Morgan T. O. , Johnston C. I.
Published: August 2015

1. Serial changes in plasma renin activity and plasma angiotensin levels were followed in rats during acute renal failure induced by mercuric chloride or glycerol.

2. During mercuric chloride-induced acute renal failure there were transitory large increases in plasma renin and angiotensin. In contrast, rats with acute renal failure produced by glycerol had a reduction in plasma renin and angiotensin levels at 1 h, after which the levels returned to control values.

3. There was no correlation between the systemic changes in plasma renin and angiotensin and the mortality from or severity of the renal failure.

4. Passive or active immunization of rats to angiotensin afforded no protection against renal failure associated with either glycerol or mercuric chloride.

5. It is concluded that the renin-angiotensin system plays no direct systemic vasoconstrictor role in the production of acute renal failure in these experimental models in rats.
Effect of Oxygen on Sodium Transfer across the Isolated Frog Skin
Authors: Norman J. N. , Shearer J. R. , Smith G.
Published: August 2015

1. The effect of high oxygen pressures on sodium transport across the isolated frog skin was investigated.

2. No effect on sodium transport was found when the skin was exposed to oxygen at 2 atmospheres pressure for 1 h.
Cardiopulmonary Blood Volume in Borderline Hypertension
Authors: Safar M. E. , Weiss Y. A. , London G. M. , Frackowiak R. F. , Milliez P. L.
Published: August 2015

1. A haemodynamic study which included estimation of cardiopulmonary blood volume (CPBV), total blood volume (TBV) and vascular reactivity to noradrenaline was performed in seventeen borderline and sixteen permanent hypertensive patients.

2. Borderline hypertensive patients had higher values of cardiac index, stroke index and heart rate when compared with the permanent hypertensive patients, and lower values of blood pressure and total peripheral resistance.

3. The CPBV/TBV ratio was significantly higher in borderline hypertensive patients. In that group, this ratio was directly correlated with cardiac index, stroke index and the pressor dose of noradrenaline (P < 0.01).

4. In permanent hypertensive patients, none of these correlations was observed. Only the total blood volume was correlated directly with cardiac index and inversely with total peripheral resistance.

5. The study suggests that a redistribution of intravascular volume from peripheral veins to the cardiopulmonary capacitance bed occurs in borderline hypertension when compared with permanent hypertension and that hypertension is related to a neural mechanism in the borderline state and to a volume mechanism in the permanent state.
Cardiorespiratory Adaptations at the Start of Exercise in Normal Subjects and in Patients with Chronic Obstructive Bronchitis
Authors: Spiro S. G. , Hahn H. L. , Edwards R. H. T. , Pride N. B.
Published: August 2015

1. The time-courses of the respiratory changes at the start of exercise were assesse in twenty middle-aged normal men and in twenty patients with chronic obstructive bronchitis with a moderate reduction in forced expiratory volume in 1 s (FEV1) (group M: mean 1.451; range 1.0–2.2 1) and in twenty patients with a more severe reduction in FEV1 (group S: mean 0.62 1; range 0.2–0.9 1). All subjects exercised at a constant work rate for 6 min, starting abruptly from a steady resting state. Cardiac frequency (fH), ventilation (V̇E), oxygen uptake (V̇o2) and carbon dioxide output (Vco2) were measured at the end of each minute and the rates of adaptation of these variables determined.

2. When the normal middle-aged men exercised at a low work rate [mean V̇o2 = 44.7 mmol (1.0 1 STPD) min−1] the increases by the end of the first minute were in the order: f H > V̇E > V̇o2 > V̇co2. At a work rate of 50% of their working capacity [V̇o2 = 67.1 mmol (1.5 1 STPD) min−1] the pattern of adaptation in the normal subjects was fH > V̇o2 > V̇E > V̇co2. In the patients working at 50% of their working capacity [V̇o2 approximately 44.6 mmol (1.01 STPD) min−1], the rates of adaptation were in the order: fH > V̇o2 >V̇E > V̇co2, but all adapted significantly more slowly than in the normal subjects exercising at the same work rate.

3. A reduced ventilatory capacity does not appear to be associated with any special influence on the time-course of the ventilatory adaptation at the start of exercise. The rate of adaptation of V̇E at the start of exercise is (in common with that of fH, V̇o2 and V̇co2) reduced in proportion to the overall reduction in working capacity.
Comparison of Effects of Locally Infused Angiotensin I and II on Hand Veins and Forearm Arteries in Man: Evidence for Converting Enzyme Activity in Limb Vessels
Authors: Collier J. G. , Robinson B. F.
Published: August 2015

1. The effects of angiotensin I (AI) and angiotensin II (AII) have been compared during local infusions into peripheral arteries and veins in man.

2. Both AI and AII produced constriction of hand veins and forearm arteries; the potency of AI was somewhat less than AII.

3. When infused into the vein, the converting enzyme inhibitor SQ 20,881 abolished or markedly attenuated the effect of AI but not that of AII.

4. The results suggest the local presence of converting enzyme in human peripheral arteries and veins.
A Study of Factors Influencing Relief of Discomfort in Breath-Holding in Normal Subjects
Authors: Rigg J. R. A. , Rebuck A. S. , Campbell E. J. M.
Published: August 2015

1. Two series of experiments were performed in an attempt to elucidate the mechanism of relief of the discomfort of breath-holding.

2. In the first the effect of varying the size of a single breath at the breaking point of breath-holding on the time of a second breath-hold (BHT2) was observed in three normal subjects. The effect of two different non-ventilatory chest-wall manœuvres, performed at the breaking point, on the duration of a second breath-hold in two additional subjects was then studied.

3. The volume of an unrestricted relieving breath was always greater than 70% of vital capacity. When the size of the breath was restricted to as little as 20% of the free relieving volume, BHT2 was unchanged.

4. An inspiratory effort against an occluded airway or an isovolume movement of the rib cage and abdomen performed at the breaking point of breath-holding were as effective as a control relieving breath in allowing resumption of apnoea.

5. There seem to be two possible mechanisms of relief. First, afferent information may be generated by some consequence of diaphragmatic contraction. Secondly, changes of local pressure-volume relationships within the lung may alter the pattern of vagal afferent activity, independent of an overall change in lung volume.
Assay Using Brain Homogenate for Measuring the Antioxidant Activity of Biological Fluids
Authors: Stocks J. , Gutteridge J. M. C. , Sharp Rosemary J. , Dormandy T. L.
Published: August 2015

1. Fresh ox-brain homogenate prepared under standard conditions at 4°C and stored at −20°C autoxidizes spontaneously and reproducibly when re-heated to 37°C.

2. The preparation can be used for assaying the antioxidant activity of serum and of other biological fluids. The preparatory and assay procedures are described.

3. The antioxidant activity of normal serum, cerebrospinal fluid, synovial fluid and of various known antioxidants have been compared.
The Inhibition of Lipid Autoxidation by Human Serum and its Relation to Serum Proteins and α-Tocopherol
Authors: Stocks J. , Gutteridge J. M. C. , Sharp Rosemary J. , Dormandy T. L.
Published: August 2015

1. The inhibitory (antioxidant) effect of serum on the autoxidation of tissue polyunsaturated fatty acids has been investigated.

2. Dialysis studies, DEAE-cellulose chromatography, gel filtration, immunoelectrophoresis and immunodiffusion experiments showed that this effect is the function of two serum protein fractions.

3. One fraction was identified as transferrin. The second fraction includes caeruloplasmin.

4. Studies with radioactively labelled α-tocopherol showed that serum tocopherol in the physiological concentration range contributes only marginally to the total antioxidant activity of serum.

5. These findings are discussed in the wider context of biological antioxidant protection.
Plasma Free Fatty Acid and Triglyceride Transport Kinetics in Man
Authors: Kissebah A. H. , Adams P. W. , Wynn V.
Published: August 2015

1. Studies were carried out to test the assumptions involved in the calculation of free fatty acid (FFA) and triglyceride transport rates from the plasma radioactivity curves after the intravenous administration of labelled fatty acid or of pre-labelled lipoprotein triglyceride.

2. Plasma FFA equilibrates reversibly with the interstitial lymph. This makes it necessary to use either a pulse injection, with analysis of the results in terms of a two-compartment model, or continuous infusion of the label in determining the FFA flux.

3. The recycling of labelled fatty acid due to direct hydrolysis of plasma triglyceride accounted for less than 5% of the total plasma FFA flux and did not appreciably affect the plasma triglyceride disappearance curve after endogenous labelling with 14C-labelled fatty acid. Turnover values calculated from triglyceride in unfractionated plasma represent mainly the very-low-density lipoprotein triglyceride transport. The distribution space of plasma triglyceride was found to be equal to the plasma volume.

4. Our findings suggest a complex relation between plasma triglyceride concentration and its transport kinetics. The plasma triglyceride concentration is determined by the rates of influx and efflux, and this concentration also regulates its own production and removal. Evidence obtained from the endogenous labelling technique and after experimental hypertriglyceridaemia suggests the application of enzyme kinetic models to characterize plasma triglyceride transport.
Aldosterone and its Regulation during Diuresis in Patients with Gross Congestive Heart Failure
Authors: Nicholls M. G. , Espiner E. A. , Donald R. A. , Hughes H.
Published: August 2015

1. Plasma aldosterone concentration and urine aldosterone excretion were studied before and during sustained diuresis in six patients with gross congestive heart failure, under conditions of fixed sodium and potassium intake and strict control of body posture. Simultaneous measurements of plasma renin activity, plasma corticotrophin and electrolytes were made to assess the relative importance of these factors in the regulation of aldosterone secretion before and during treatment of congestive heart failure.

2. During the pre-treatment phase aldosterone levels were normal or raised, but with acute diuresis fell to unmeasurable levels in most cases. This depression in aldosterone tended to coincide with peak natriuresis. Later in the diuretic phase aldosterone values increased often to very high levels as dry body weight was attained.

3. With few exceptions plasma renin activity fluctuations paralleled those of plasma aldosterone, whereas corticotrophin levels remained largely within normal limits and plasma electrolytes did not change appreciably.

4. The results suggest that the renin—angiotensin system is the important regulator of aldosterone secretion before and during diuretic treatment in patients with gross congestive heart failure.
Quantitative Radioisotope Renography: The Derivation of Physiological Data by Deconvolution Analysis Using a Single-Injection Technique
Authors: Reeve J. , Crawley J. C. W.
Published: August 2015

1. An improved method is presented for quantifying all the information relating to individual kidney function that is contained in the renogram.

2. From the convolution theorem, functions are derived which are equivalent to the renograms that would be obtained by simultaneous injections of the indicator into each renal artery, fractionated according to renal blood flow.

3. The ‘pulse-input’ renograms so derived can have the blood background subtracted by a process of ‘kinetic discrimination’, which dispenses with the prior injection of human serum albumin.

4. The ‘pulse-input’ renograms with blood background subtracted are analysed by the techniques used in conventional indicator dilution methods.

5. The value of this approach in clinical and experimental work is illustrated by comparison of examples drawn from 400 consecutive studies of patients with normal data.
Specificity of Blockade of Renal Renin Release by Propranolol in the Cat
Authors: Johns E. J. , Singer Bertha
Published: August 2015

1. The anaesthetized cat, unilaterally nephrectomized and with renal nerves sectioned, has been used in a study of the specificity of the inhibitory effect of propranolol on renin release.

2. The effect of (+)-propranolol on the rise in plasma renin activity (PRA) induced by renal nerve stimulation has been examined. When administered at approximately the same dose as the racemic mixture which blocks renin release in response to this stimulus, (+)-propranolol did not significantly reduce the magnitude of the response. Therefore the action of racemic propranolol in blocking the response to neural stimulation can be attributed to the (−)-isomer.

3. Renal artery constriction, producing blood flow changes similar to those resulting from renal nerve stimulation, also induces a rise in PRA. (±)-Propranolol, in amounts which block the rise in PRA observed with renal nerve stimulation, did not prevent the increase seen with renal artery constriction.

4. Reduction of renal perfusion pressure within the autoregulatory range for 20 min resulted in a rise in PRA in all experiments. (±)-Propranolol did not significantly affect the response.

5. It is concluded that the release of renin in response to renal nerve stimulation cannot be attributed to associated changes in renal blood flow. The evidence is compatible with a direct action of the neurotransmitter on renin-containing cells via a β-adrenergic receptor. When renin release is induced by non-adrenergic mechanisms propranolol blockade has no significant effect on the response.
Reduced Serum Somatomedin Activity in Patients with Chronic Liver Disease
Authors: Wu A. , Grant D. B. , Hambley Judy , Levi A. J.
Published: August 2015

1. Somatomedin (SM; sulphation factor) activity was estimated by a chick-cartilage assay in fasting sera from twenty-one patients with chronic liver disease.

2. Low SM values were found in nine out of the ten patients with cirrhosis and in two other patients, one with hepatofibrosis and one with hepatoma.

3. In general, the lowest serum SM activities were found in those patients with the most severe disease and significant correlations were found between serum SM and serum albumin, alkaline phosphatase and bilirubin.

4. Growth hormone was also measured in the samples and concentrations above 10 units/ml were found in seven patients, all of whom had reduced serum SM activities.

5. These findings indicate that low serum SM activity in liver disease is not related to growth hormone deficiency and suggest that the liver may be an important site for SM synthesis in man.
Unesterified Fatty Acids and the Binding of Tryptophan in Human Plasma
Authors: Curzon G. , Friedel June , Katamaneni Bharati D. , Greenwood Monica H. , Lader M. H.
Published: August 2015

1. The percentage of human plasma tryptophan in the free state (ultrafilterable) was positively and significantly correlated with plasma non-esterified fatty acid (NEFA) concentration.

2. Results obtained either by adding tryptophan to plasma in vitro or from plasma taken during tryptophan infusion indicate one tryptophan binding site per albumin molecule and an inverse relationship between binding constants and NEFA concentration.

3. A single normal subject was atypical as the apparent number of binding sites varied between one and two per albumin molecule (1.54±0.49 sd, four experiments).

4. Spontaneous increases of plasma NEFA during tryptophan infusion were associated with increased free tryptophan. Also addition in vitro of linoleic acid, oleic acid and palmitic acid to plasma caused free tryptophan to increase.

5. The possible significance of NEFA changes on plasma tryptophan binding in various pathological circumstances is discussed.
Serial Studies of the Renal Clearance of Urate and Inulin during Pregnancy and after the Puerperium in Normal Women
Authors: Semple P. F. , Carswell W. , Boyle J. A.
Published: August 2015

1. A serial study of renal clearance of urate and inulin was made in thirteen normal women in early, mid and late pregnancy and 6–15 weeks after delivery.

2. The mean serum urate concentration was low in early and mid pregnancy but rose in late pregnancy towards the control value.

3. Clearances of urate and inulin were consistently elevated throughout pregnancy to about 150% of the post-partum values. The ratio of clearance of urate to clearance of inulin was the same in pregnancy as it was after the puerperium.

4. The urinary excretion of urate was increased only in late pregnancy.
Experimental Acute Hepatic Encephalopathy: Comparison of the Electroencephalographic Changes in the Liverless and in the Eviscerated Rat
Authors: Degos Francine , Degos J.-D. , Bourdiau Denise , Peignoux Michèle , Prandi Danièle , Roche-Sicot Jacqueline , Sicot C. , Rueff B. , Benhamou J.-P.
Published: August 2015

1. The present work was carried out to compare the electroencephalographic changes in liverless rats and eviscerated rats and to determine whether substances released from the intestine, in particular ammonia, play a major part in the mechanism of hepatic encephalopathy.

2. The animals were prepared according to a three-stage procedure: ligation of inferior vena cava; 3 weeks later, end-to-side portacaval shunt; 2 days later, removal of the liver (liverless rats) or removal of the liver, spleen, stomach, intestine and pancreas (eviscerated rats).

3. In liverless rats, the electroencephalographic changes began 4–8 h after hepatectomy with a predominance of ‘slow’ sleep pattern followed by increasing changes, which consisted successively of (a) alteration of, then disappearance of, spindles of high-voltage waves; (b) predominance of slow waves; (c) depression in voltage and finally flat tracing. The mean duration of survival was 18.4 h. Mean plasma ammonia concentration 15 h after hepatectomy was 353 μmol/l.

4. In eviscerated rats, the electroencephalographic changes were similar. The mean duration of survival was 21.3 h, which is not statistically different from that of liverless rats. Mean plasma ammonia concentration 15 h after evisceration was 148 μmol/l, a value significantly lower than that of liverless rats.

5. These results suggest that ammonia, and substances released from the intestine in general, play no part or at most a minor role in the mechanism of hepatic encephalopathy of the liverless rat.
Glutathione Peroxidase Deficiency with Increased Susceptibility to Erythrocyte Heinz Body Formation
Authors: Hopkins J. , Tudhope G. R.
Published: August 2015

1. The production of Heinz bodies, after incubation of erythrocytes in the presence of hydrogen peroxide vapour, was significantly greater in erythrocytes with abnormally low glutathione peroxidase (GSH-Px) activity than in cells with normal enzyme activity.

2. The addition of the catalase inhibitor, sodium azide, to the incubation mixture, increased the formation of Heinz bodies after exposure to hydrogen peroxide vapour; the percentage of Heinz bodies was significantly greater in erythrocytes with low GSH-Px activity than in normal erythrocytes.

3. Erythrocyte GSH-Px deficiency thus predisposes the cell to Heinz body formation when exposed to oxidant stress.
Partial Pressures of Oxygen and Carbon Dioxide, and pH of Blood Sampled from Wedged Pulmonary Artery
Authors: Chlup J. , Šerf B. , Ouředník B. , Parkmannová A.
Published: August 2015

1. Po2, Pco2 and pH were examined in twenty-seven pulmonary ‘wedge’ samples of blood obtained from seventeen patients with various heart diseases.

2. High Po2 and pH, and low Pco2, values were found in comparison with those in simultaneous samples of peripheral arterial blood. In the pulmonary ‘wedge’ samples of blood, the following mean values were found: Po2, 17.65 kPa (132.2 mmHg); Pco2, 3.10 kPa (23.2 mmHg); pH 7.47. An explanation of these findings is considered.
Measurement of Intrarenal Blood-Flow Distribution in the Rabbit Using Radioactive Microspheres
Authors: Warren D. J. , Ledingham J. G. G.
Published: August 2015

1. Total renal blood flow and its distribution within the renal cortex of the conscious rabbit were studied with radioactive microspheres of 15 and 25 μm diameter.

2. The reliability of the microsphere technique was influenced by microsphere diameter and number (dose). The optimum microsphere diameter for determination of flow distribution in the rabbit kidney was 15 μm and dose 100–150 000 spheres.

3. Spheres of 15 μm nominal diameter were randomly distributed within the renal cortex of adult rabbits. The larger spheres in batches nominally 15 μm in diameter in young rabbits and 25 μm diameter in adult rabbits were preferentially distributed to the superficial cortex.

4. In adult rabbits 15 μm diameter spheres lodged in glomerular capillaries. Larger spheres occasionally lodged in interlobular arteries causing intrarenal haemorrhage.

5. Microspheres of 15 μm caused a decrease in renal clearance of creatinine and of p-aminohippurate when the total injection dose was about 200 000 spheres. These effects were greater when the injection dose was increased to 500 000 spheres.

6. The reduction in total renal blood flow observed with large doses of spheres largely reflected decreased outer cortical flow, as measured by a second injection of spheres, and confirmed by a decrease in p-aminohippurate extraction.

7. The reproducibility of multiple injection studies was limited by these intrarenal effects of microspheres.

8. Total renal blood flow measured in six rabbits in acute experiments by the microsphere technique was 107 ± 12 (mean±sd) ml/min and by p-aminohippurate clearance was 100 ± 10 ml/min.

9. Total renal blood flow in twelve conscious, chronically instrumented rabbits was 125 ± 11 ml/min, of which 92 ± 6 ml/min was distributed to the superficial cortex and 33 ± 4 ml/min to the deep cortex.
Deoxycorticosterone Excretion in Normal, Hypertensive and Hypokalaemic Subjects
Authors: Cope C. L. , Loizou S.
Published: August 2015

1. Radioimmunoassay has been used to detect and estimate the urinary excretion of deoxycorticosterone (DOC) in normal, hypertensive and hypokalaemic subjects. The range of excretions in ten healthy normal subjects was 41–232 pmol (13.7–76.7 ng) daily, with a mean of 124 pmol (41 ng).

2. In fourteen subjects with essential hypertension without metabolic disturbance the range found was 29–144 pmol (9.7–47.7 ng) daily, with a mean of 87 pmol (28.8 ng), which is not significantly different from that in normal subjects.

3. In twelve patients with Cushing's syndrome due to adrenal cortical hyperplasia the range found was 26–542 pmol (8.7–179 ng). Ten of these twelve patients had values within normal limits.

4. Of nine subjects showing hypokalaemia, eight had elevated excretion of deoxycorticosterone with values from 263 to 5515 pmol (87–1820 ng) daily. Seven of these were hypertensive and two were normotensive. The elevated excretion of deoxycorticosterone found in hypokalaemic subjects is thus not confined to those with hypertension.

5. No correlation has been found between excretion rates for aldosterone and deoxycorticosterone. Raised excretion of the latter provides an indicator of disturbed adrenal cortical metabolism.