bluuebunny/crossref_metadata_2025 huggingface dataset:
Haemodynamic and Neurohumoral Changes in Spontaneously Hypertensive Rats with Aortocaval Fistulae
Authors: Oka Tamiko , Nishimura Hikaru , Ueyama Masakuni , Kubota Jiro , Kawamura Keishiro
Published: August 2015

1. Our aim was to evaluate the effects of an aortocaval fistula (1 mm) on cardiorenal haemodynamics, cardiac hypertrophy and neurohumoral factors in spontaneously hypertensive rats and to compare the results with those observed in Wistar rats at 2 weeks after fistulae placement. Sham-operated spontaneously hypertensive rats and Wistar rats served as controls.

2. Heart weight was significantly increased in spontaneously hypertensive rats (34%) and in Wistar rats (43%) at 2 weeks after fistula creation. Left ventricular systolic pressure and dp/dtmax. were significantly decreased (both P <0.01) in spontaneously hypertensive rats with fistulae which had higher left ventricular end-diastolic pressure than Wistar rats with fistulae (P <0.01). Signs of circulatory congestion (ascites, tachypnoea, prostration) were observed only in the overloaded spontaneously hypertensive rats (45%). Cardiac index was comparably increased in both fistulae groups due to an increase in stroke index, since heart rate was not increased.

3. Fistulae placement decreased renal blood flow and kidney weight, and increased blood urea nitrogen to a greater degree in spontaneously hypertensive rats (all P <0.05); serum creatinine levels were unaltered. Plasma noradrenaline concentration was increased in spontaneously hypertensive rats with fistulae (P <0.05), whereas plasma renin activity was not changed.

4. Thus, spontaneously hypertensive rats with fistulae developed overt haemodynamic signs of high-output heart failure with frequent ascites and dyspnoea, whereas most of these findings were milder or absent in Wistar rats. This model provides an opportunity to evaluate the pathophysiological and pharmacological responses in high-output heart failure.
Effect of Splenic Congestion Associated with Haemolytic Anaemia on Filtration of ‘Spleen-Homing’ Microspheres
Authors: Moghimi S. M. , Hedeman H. , Illum L. , Davis S. S.
Published: August 2015

1. The surface of large model 125I-labelled polystyrene microspheres (220 nm in diameter) was coated with the polyoxyethylene/polyoxypropylene block co-polymer poloxamine-908. The coated microspheres were injected intravenously into rats. Up to 40% of the administered dose had accumulated in the spleen by a filtration mechanism, as compared with 5% for uncoated microspheres, at 3 h after administration. The enhanced splenic sequestration of microspheres was accompanied by a decrease in the liver uptake. In contrast, smaller poloxamine-908-coated microspheres (60 nm in diameter) effectively avoided uptake by both the liver and the spleen and remained in systemic circulation.

2. The effect of splenic congestion, associated with phenylhydrazine-induced haemolytic anaemia, on filtration of poloxamine-908-coated microspheres was studied. The enlarged spleen of the anaemic rats was incapable of efficiently filtering large poloxamine-908-coated microspheres when compared with the spleen of normal animals. This was suggested to be the result of extensive ‘clogging’ of the red pulp by damaged erythrocytes. However, the splenic filtration of large coated microspheres was still five-fold higher than that of uncoated microspheres of similar size in anaemic animals.

3. The potential use of large sterically stabilized colloids and drug carriers for selective spleen scanning and splenic drug delivery in pathological conditions, where anaemia prevails, is discussed.

4. Sterically stabilized microspheres may have potential for re-examining the microcirculatory pathways in healthy spleen and various splenomegalies.
Low Platelet Glutathione Peroxidase Activity and Serum Selenium Concentration in Patients with Chronic Renal Failure: Relations to Dialysis Treatments, Diet and Cardiovascular Complications
Authors: Girelli Domenico , Olivieri Oliviero , Stanzial Anna Maria , Azzini Margherita , Lupo Antonio , Bernich Patrizia , Menini Carlo , Gammaro Linda , Corrocher Roberto
Published: August 2015

1. Selenium status was investigated in patients with chronic renal failure, with special regard to its relations to the dialysis treatments, dietary habits and clinical signs of atherosclerosis.

2. Serum selenium concentration and platelet glutathione peroxidase activity were measured in 45 patients with chronic renal failure subdivided into three groups according to the type of treatment: 15 non-dialysed, 15 on haemodialysis, 15 on continuous ambulatory peritoneal dialysis. A 7-day diet history was carried out in all patients. Seventeen of the patients with chronic renal failure had clinically overt cardiovascular disease. Forty-five age-matched healthy subjects were considered as controls.

3. Both serum selenium concentration and platelet glutathione peroxidase were significantly reduced in all patients with chronic renal failure compared with control subjects; a direct and significant correlation was found between the two parameters. No differences in selenium status were observed among the non-dialysed, haemodialysis and continuous ambulatory peritoneal dialysis groups. No correlation between total calorie or protein intakes and selenium indices were observed. The chronic renal failure patients with cardiovascular complications showed a further significant reduction in both serum selenium concentration and platelet glutathione peroxidase activity as compared with the patients without cardiovascular complications; these two groups were similar with respect to the other well-known cardiovascular risk factors (age, smoking, plasma lipids, hypertension, body mass index).

4. It is concluded that a low selenium concentration is present in chronic renal failure, which is independent of dialysis and is accompanied by biological repercussion in terms of reduced platelet glutathione peroxidase activity. It may represent a previously unrecognized cofactor favouring the ‘accelerated’ atherosclerosis of patients with chronic renal failure.
Localization of Cyclosporin a Absorption in Rat Small Bowel and the Effect of Bile
Authors: Cakaloglu Yilmaz , Marinos George , Marsden Joanne , Peters Timothy J. , Williams Roger , Tredger J. Michael
Published: August 2015

1. Cyclosporin A absorption was examined after the instillation of approximately 2 mg/kg into four segments (mean length 15 cm) of rat small bowel, isolated in situ in fed Wistar female rats: SI (duodenum and proximal jejunum distal to the common bile duct); SII (distal jejunum); SIII (proximal ileum) and SIV (distal ileum).

2. Cyclosporin A concentrations in whole blood were assayed by an enzyme-mediated immunoassay for up to 4 h in samples drawn from the femoral vein and used to determine the following pharmacokinetic parameters: the area under the blood cyclosporin A concentration versus time curve (AUC, 0–4 h), the maximum blood concentration of cyclosporin A (Cmax.), the time to reach Cmax. (tmax.), the absorption half-life (t1/2a), the elimination half-life (t1/2λ), and the mean residence time (MRT).

3. Cyclosporin A absorption in SI (AUC, 991 μ l−1 h) was nearly double that in more distal segments and decreased progressively (SII, 533 μg l−1 h; SIII, 470 μg l−1 h; SIV, 419 μg l−1 h). There were corresponding differences in Cmax: 327 μg/l in SI and 201 μg/l, 169 μg/l and 151 μg/l in SII, SIII and SIV, respectively. Tmax. was shorter in SIV (0.9 h) than in other segments (1.3-1.5 h), but there were no significant differences between the segments for t1/2a, t1/2λ or MRT.

4. In the presence of continuous bile flow (diverted via a cannula for SIV), cyclosporin A absorption significantly increased by 23% in SI and by 50% in SIV, but the differential between absorption in SI and SIV was maintained.

5. We conclude that cyclosporin A is absorbed throughout the rat small intestine with the greatest absorption rate in the proximal duodenum and jejunum, and that bile significantly augments cyclosporin A absorption in both the proximal and particularly the distal small bowel.
Ventricular Expression and Circulating Levels of Immunoreactive Dynorphin in Heart Transplant Recipients
Authors: Ationu Art , Sorensen Keld , Whitehead Bruce , Singer Donald , Carter Nicholas
Published: August 2015

1. Dynorphin, an endogenous opioid peptide, acts on specific κ-opioid receptors in the rat heart for the local regulation of atrial natriuretic peptide release. No known study has examined the expression of dynorphin in the human heart.

2. In the present study a specific radioimmunoassay technique was used to determine ventricular expression of dynorphin at the peptide level in endomyocardial biopsy specimens and in plasma obtained from 13 heart transplant recipients. Ventricular biopsy specimens collected from 10 patients without cardiac complications during necropsy (less than 24 h from time of death) and plasma samples from 10 normal healthy subjects were used as controls.

3. The immunoreactive level of ventricular dynorphin was higher in heart transplant recipients (mean ± SEM 141 ± 32 pg/mg of soluble protein, range 7–573 pg/mg of soluble protein, P <0.001) than in control subjects (16 ± 3 pg/mg of soluble protein, 2–34 pg/mg of soluble protein). The plasma concentration of immunoreactive dynorphin was also higher (P <0.001) in heart transplant recipients (mean ± SEM 14 ± 1 pg/ml, range 5–39 pg/ml) than in normal healthy subjects (7 ± 0.4 pg/ml, 5–10 pg/ml). No relationship was observed between ventricular and plasma levels of dynorphin.

4. These results show that immunoreactive levels of dynorphin in plasma and ventricle are increased after heart transplantation, suggesting a possible pathophysiological role for dynorphin in the heart.
Atrial Natriuretic Peptide-Cyclic Gmp Relationships in Normal Humans: Effects of Dietary Sodium Intake
Authors: Sagnella G. A. , Markandu N. D. , Buckley M. G. , Singer D. R. J. , MacGregor G. A.
Published: August 2015

1. The present study was designed to investigate the relationships between circulating atrial natriuretic peptide, plasma and urinary cyclic GMP and sodium excretion under basal conditions and in response to changes in dietary sodium intake.

2. Measurements of plasma atrial natriuretic peptide and plasma and urinary (24 h collections) cyclic GMP, sodium and creatinine were made in (i) 30 normotensive subjects on their normal sodium intake and (ii) 12 subjects on the 5th day of a low and on the 5th day of a high sodium intake.

3. Plasma cyclic GMP, urinary cyclic GMP and fractional excretion of cyclic GMP in 30 normotensive subjects on their normal sodium intake were (means ± SEM) 5.4 ± 0.5 pmol/ml, 434.5 ± 31.8 pmol/min and 86.9 ± 8.6%, respectively. There were significant correlations between urinary cyclic GMP and its corresponding filtered load (r = 0.55) and between the renal clearance of cyclic GMP and that of creatinine (r = 0.44), but there were no significant associations between circulating atrial natriuretic peptide and plasma cyclic GMP or the fractional excretion of cyclic GMP or between urinary sodium and the fractional excretion of cyclic GMP.

5. Plasma atrial natriuretic peptide was significantly raised on the 5th day of the high sodium intake compared with the low sodium intake (10.6 ± 1.6 versus 4.2 ± 0.9 pg/ml; P <0.05). Similarly, there were increases in urinary cyclic GMP excretion (692.3 ± 43.4 versus 427.4 ± 41.9 pmol/min, P <0.05), but there were no significant differences in the fractional excretion of cyclic GMP.

6. As neither plasma nor urinary cyclic GMP was strongly associated with circulating levels of atrial natriuretic peptide, the present study suggests that other factors may be more important than circulating atrial natriuretic peptide as determinants of extracellular cyclic GMP.
Early Increase in Glomerular Leucocyte Number after a Reducton in Renal Mass: Implications for the Pathogenesis of Glomerulosclerosis
Authors: Harris K. P. G. , Baker F. , Brown J. , Walls J.
Published: August 2015

1. Adult female Wistar rats underwent uninephrectomy (n = 8) through a flank incision, or a sham operation (n = 7). One to two weeks later the kidney was perfused in situ and glomeruli were isolated from cortical tissue by sequential sieving, and partially digested. Glomerular leucocytes were labelled with a mouse monoclonal antibody against leucocyte common antigen followed by a fluorescein-labelled anti-mouse immunoglobulin to allow counting.

2. In a further group of animals 24 h albumin excretion and glomerular size were measured 2 weeks after either uninephrectomy (n = 6) or sham operation (n = 6).

3. Glomerular leucocyte number was significantly increased in uninephrectomized animals (15.7 ± 0.9 versus 8.9 ± 0.4, P <0.001), with some glomeruli having leucocyte numbers comparable with those seen in glomerulonephritis.

4. Albuminuria was not increased 2 weeks after uninephrectomy (233 ± 35 versus 170 ± 42 μg/24 h, not significant), and glomerular size was unchanged. Light microscopical appearance was normal.

5. An increase in glomerular leucocyte number is an early response in what was previously considered a non-immunological lesion. It precedes the development of renal scarring and may be important in the pathogenesis of this process.
Separate Effects of Urinary Chondroitin Sulphate and Heparan Sulphate on the Crystallization of Urinary Calcium Oxalate: Differences between Stone Formers and Normal Control Subjects
Authors: Shum D. K. Y. , Gohel M. D. I.
Published: August 2015

1. Urinary glycosaminoglycans were recovered from the papain digest of polyanions precipitated sequentially by cetylpyridinium chloride and sodium acetate-saturated ethanol. Those from the early morning urine of 48 stone formers and 43 normal control subjects measured 11 and 16 μg of uronic acid/ml of urine, respectively.

2. Preparative agarose gel electrophoresis of the recovered glycosaminoglycans in barium acetate buffer (pH 5.8) yielded fractions containing purely chondroitin sulphate, co-polymeric chondroitin/dermatan sulphates and heparan sulphate. Identification was based on the susceptibility of the fractions to chondroitinase or nitrous acid treatment. Similar compositions of glycosaminoglycan classes were observed in samples from stone formers and normal control subjects.

3. The fractionated glycosaminoglycans were dissolved in urine ultrafiltrate to assay for nucleation-promoting and growth-inhibiting activities towards crystallization of urinary calcium oxalate. When compared at the same uronic acid concentration, both the urinary chondroitin sulphate isomers and heparan sulphates of stone formers demonstrated the capacity to enhance crystal nucleation from calcium oxalate endogenous in urine ultrafiltrates, whereas only urinary heparan sulphates of normal control subjects demonstrated this capacity.

4. Tissue-derived reference chondroitin sulphate, dermatan sulphate and heparin, when similarly tested, showed negligible crystal nucleation-promoting activity. The tissue-derived heparan sulphate was similar to the urinary heparan sulphates in showing marked crystal nucleation-promoting activity.

5. Crystal-growth inhibitory activity was evident in all urinary glycosaminoglycan fractions studied. In particular, urinary heparan sulphate of normal control subjects showed higher activity than that of stone formers or the chondroitin sulphate isomers of both stone formers and normal control subjects (P <0.005).
Renal Functional Response to Ischaemic Renal Failure in Chronic Hypoxic Rats
Authors: Chen C. F.
Published: August 2015

1. Chronic hypoxic rats are always polycythaemic. It is possible that an increase in packed cell volume may enhance erythrocyte trapping with a consequent increase in renal damage after renal ischaemia. These experiments were designed to assess renal functional changes after renal arterial occlusion in chronic hypoxic rats.

2. Chronic hypoxic rats were prepared by exposure (15h/day) to an altitude chamber (5486 m) for 4 weeks.

3. After 45 min of left renal arterial occlusion, there were significant decreases in the excretion of potassium, p-aminohippurate and inulin and in the p-aminohippurate extraction ratio in 12 sea level ischaemic insulted kidneys. In 12 chronic hypoxic rats, the same parameters were changed after left renal ischaemia but only the p-aminohippurate ratio was significantly altered.

4. Administrations of 1 or 5 mg/kg phosphoramidon did not cause any significant improvement in the measured renal parameters in both kidneys and in both groups of rats after ischaemia.

5. In the second experiment, the rats were challenged by rapid infusion of 10 ml of saline intravenously, and urine was collected for 90 min from each ureter. Four hours after left renal arterial occlusion, the insulted kidney showed increased water and sodium excretion in both sea level and chronic hypoxic rats. However, 24 h after left renal ischaemia, the responses of sea level and chronic hypoxic rats were different. Urinary excretion was significantly reduced in sea level rats, but was almost normal in chronic hypoxic rats.

6. This report suggests that some beneficial factors after chronic hypoxia might play important roles in reducing the damage after renal ischaemia.
Influence of Counter-Regulatory Hormones, Independently of Hypoglycaemia, on Cognitive Function, Warning Symptoms and Glucose Kinetics
Authors: Kerr David , Diamond Michael P. , Tamborlane William V. , Kerr Sara , Sherwin Robert S.
Published: August 2015

1. To assess the influence of counterregulatory hormones, independently of neuroglycopaenia, on higher cerebral (cognitive) function, ‘hypoglycaemic’ warning symptoms and glucose kinetics, 10 healthy subjects participated in two hyperinsulinaemic (2 m-units min−1 kg−1) glucose clamp studies. After 100 min of euglycaemia (plasma glucose level 5 mmol/l), the plasma glucose level was either (a) maintained at 5 mmol/l for 120 min by glucose infusion with concomitant replacement of counterregulatory hormones (continuous infusions of glucagon, adrenaline, noradrenaline, cortisol and growth hormone) to mimic the hormonal milieu normally associated with hypoglycaemia (hormone infusion study) or (b) lowered to 2.8 mmol/l for 120 min (hypoglycaemia study). Assessments were made of cognitive function (P300 auditory evoked responses), symptoms (visual analogue scales) and glucose kinetics (3-[3H]glucose).

2. Hypoglycaemia was associated with an increase in all symptoms (facial flushing, palpitations, tingling, trembling, sweating, hunger, light-headedness and sleepiness, P <0.01) and all subjects were aware that blood glucose levels had fallen. P300 evoked potential latency increased from 280 ±6 to 312 ±5 ms (mean±SEM, P <0.01). In contrast, P300 latency and several individual symptoms (hunger, facial flushing, sweating and light-headedness) did not change from baseline during the hormone infusion study (P <0.05 versus hypoglycaemia). Hepatic glucose production was lower (1.5±0.4 versus 2.3±0.3mg min−1 kg−1, P <0.05) and peripheral glucose uptake was higher (7.4±1.0 versus 5.6±0.6 mg min−1 kg−1, P <0.01) during infusion of the hormones compared with during hypoglycaemia.

3. In conclusion, the deterioration in cognitive function during hypoglycaemia is a consequence of a low plasma glucose level and is unaffected by the release of counterregulatory hormones. Counterregulatory hormones mediate some but not all of the symptomatic and kinetic responses to hypoglycaemia.
Some Pitfalls in the Measurement of Blood Glutathione
Authors: Schofield D. , Mei G. , Braganza J. M.
Published: August 2015

1. We report some pitfalls in the measurement of whole blood and plasma glutathione in man.

2. Using a simple tourniquet to the forearm and a 21-gauge needle, blood samples were collected by brachial vein puncture from healthy subjects. Whole blood and plasma were analysed for total glutathione, including the reduced and oxidized forms, by a spectrophotometric recycling method involving the glutathione reductase/NADPH couple.

3. The concentration of oxidized glutathione was determined after treatment of aliquots with either 2-vinylpyridine or N-ethylmaleimide to trap reduced glutathione. Reduced glutathione in the native samples could then be obtained by subtraction.

4. When the reagents were added to separated plasma, 2-vinylpyridine yielded values for oxidized glutathione that were twice as high as with N-ethylmaleimide. In whole blood studies the discrepancy was even greater, and the problem was not resolved by deproteinization of samples with 5-sulphosalicylic acid. Using N-ethylmaleimide, levels of oxidized glutathione were less than 1% of total glutathione in whole blood.

5. Despite attempts to minimize haemolysis, lysed erythrocytes contributed on average 25% to the ‘plasma’ glutathione concentration.
Serum Sialic Acid and Acute-Phase Proteins in Hypertriglyceridaemic Patients Showing the Frederickson's Type IIB Phenotype
Authors: Haq S. , Tutt P. , Haq M. , Crook M.
Published: August 2015

1. We have shown that serum total sialic acid is elevated in hypertriglyceridaemic patients showing the Frederickson's type IIB phenotype in comparison with normal subjects (2.30 ±0.34 versus 1.92 ± 0.32 mmol/l, P <0.02). Lipid-associated sialic acid was also elevated in the hypertriglyceridaemic group in comparison with the normal subjects (0.60 ±0.09 versus 0.35 ±0.04 mmol/l, P <0.001).

2. We measured five serum acute-phase proteins in the hypertriglyceridaemic patients and the normal subjects, namely α1-antichymotrypsin, α1-acid glycoprotein, α2-macroglobulin, C-reactive protein and haptoglobin. Serum α2-macroglobulin was significantly elevated in the hypertriglyceridaemic patients compared with the normal subjects (2.1 ±1.0 versus 1.5 ± 0.55 g/l, P <0.05) as was serum C-reactive protein (5.9 ±3.5 versus 3.5±1.9mg/l, P <0.05). There were, however, no significant differences in the serum concentrations of α1-antichymotrypsin, α1-acid glycoprotein or haptoglobin between the two groups.

3. There was a significant correlation between serum total sialic acid and serum α1-antichymotrypsin, α1-acid glycoprotein and haptoglobin (Spearman correlation coefficients 0.74, 0.50 and 0.76, respectively) in the normal subjects, and there was a significant correlation between serum total sialic acid and serum α1-antichymotrypsin and α1-acid glycoprotein (Spearman correlation coefficients 0.72 and 0.84, respectively) in the hypertriglyceridaemic patients.
Natriuretic Response to Head-Out Immersion in Humans with Recent Kidney Transplants
Authors: Rabelink Ton J. , van Tilborg Karin A. , Hené Ronald J. , Koomans Hein A.
Published: August 2015

1. Recently implanted kidneys may have decreased flexibility to adjust sodium excretion to volume challenges, since modulation by renal sympathetic nerve activity is absent. To examine this hypothesis, we studied the natriuretic response to head-out water immersion in eight patients with well-functioning renal allografts of 37 days (range 24–56 days), at a time when renal re-innervation has probably not occurred.

2. By the third hour of head-out water immersion, sodium excretion had increased equally in the patients (from 120 +21 to 204 +37 μmol/min) and in eight healthy control subjects (from 105 +9 to 191+19 μmol/min).

3. Glomerular filtration rate was 60 + 6 ml/min in the patients and 113 +6 ml/min in the control subjects, and did not change upon head-out water immersion. Estimated renal plasma flow increased upon head-out water immersion in the control group but not in the patients. Blood pressure decreased similarly in both groups. The renal vascular resistance, calculated from these data, decreased in response to head-out water immersion in the control subjects but not in the renal transplant patients.

4. Head-out water immersion suppressed plasma renin activity only in the normal group, whereas the plasma aldosterone level was suppressed in both groups. The natriuretic response in patients was associated with about 3-fold elevated plasma levels of atrial natriuretic peptide.

5. Since renal re-innervation at 37 days after transplantation is very unlikely, these data suggest that inact renal innervation is not mandatory for a normal natriuretic response to head-out water immersion in humans. However, sympathetic modulation might be involved in the decrease in renal vascular resistance and plasma renin activity normally observed during immersion.
Relationship between Markers of Endothelial Dysfunction, Oxidant Injury and Tubular Damage in Patients with Insulin-Dependent Diabetes Mellitus
Authors: Yaqoob M. , Patrick A. W. , McClelland P. , Stevenson A. , Mason H. , White M. C. , Bell G. M.
Published: August 2015

1. Diabetic nephropathy is a serious microvascular complication in patients with insulin-dependent diabetes mellitus, resulting in end-stage renal disease in 30–45% of such patients. Despite intensive investigation, the pathophysiology of diabetic renal disease has not been fully elucidated. However, several clinical and experimental studies have suggested that endothelial dysfunction and free-radical activity may be important factors.

2. Forty normotensive patients with insulin-dependent diabetes mellitus of between 10 and 20 years duration with persistent normoalbuminuria (albumin excretion <30 mg/day) and normal renal function were investigated for markers of endothelial dysfunction (plasma von Willebrand factor, soluble thrombomodulin and angiotensin-converting enzyme activity), free oxygen radical generation (erythrocytic superoxide dismutase and glutathione peroxidase) and oxidant injury (serum malondialdehyde). Glomerular proteinuria (albuminuria, transferrinuria), tubular proteinuria (retinol-binding protein) and tubular enzymuria (N-acetyl glucosaminidase and leucine aminopeptidase) were also measured.

3. Patients were divided into two groups. Group 1 comprised 21 patients with elevated markers of endothelial dysfunction, and group 2 comprised 19 patients with normal levels of plasma von Willebrand factor, soluble thrombomodulin and angiotensin-converting enzyme activity. Thirty-eight healthy subjects matched for age and sex acted as controls.

4. Groups 1 and 2 were similar in age, sex, body weight, duration of diabetes mellitus and recent glycaemic control. Serum cholesterol, serum creatinine and glomerular proteinuria were similar in the three groups. Group 1 patients had significantly increased oxidant injury, tubular enzymuria and proteinuria compared with group 2 patients and control subjects (P <0.01). Erythrocytic glutathione peroxidase was significantly lower in group 1 compared with the other groups (P <0.01) and erythrocytic superoxide dismutase was lower in both diabetic groups compared with normal control subjects (P <0.01). Serum malondialdehyde, tubular enzymuria and proteinuria were comparable in group 2 patients with control subjects.

5. We conclude that endothelial dysfunction, oxidant injury and renal tubular damage may precede microalbuminuria in diabetic nephropathy. These data support the hypothesis that endothelial dysfunction first affects the postglomerular microvessels. It is associated with oxidant injury and renal tubular damage, which may be factors in the initiation of diabetic nephropathy.
Impact of Treatment with Acetylsalicylic Acid on the Proaggregatory Effects of Adrenaline in vitro in Patients with Stable Angina Pectoris: Influence of the Anticoagulant
Authors: Wallén N. Håkan , Held Claes , Rehnqvist Nina , Hjemdahl Paul
Published: August 2015

1. The impact of oral acetylsalicylic acid treatment on the enhancing effect of adrenaline on platelet aggregation in vitro was investigated in patients with stable angina pectoris. In addition, the influence of different anticoagulants (i.e. hirudin and citrate) on platelet aggregation in vitro was compared.

2. Eighty-four patients with stable angina pectoris were studied. Sixteen patients were on acetylsalicylic acid treatment (150-250 mg daily), whereas 68 patients were free from acetylsalicylic acid. Platelet-rich-plasma was prepared from citrate- or hirudin-antkoagulated blood. The EC50 (i.e. the concentration of agonist required to produce half-maximal aggregation) for the ADP-induced extent of aggregation was determined. Thereafter the enhancing effect of adrenaline (10 and 50 nmol/l) on ADP-induced aggregation (at EC50) was investigated.

3. In the patients with angina, acetylsalicylic acid caused the expected effects on ADP-induced platelet responses. Adrenaline significantly enhanced both the extent of aggregation and the initial rate of aggregation (primary aggregation), irrespective of the anticoagulant used. In acetylsalicylic acid-treated patients (citrated platelet-rich plasma) the extent of aggregation was partly inhibited, but no significant effect on the rate of aggregation could be observed.

4. A comparative substudy of the anticoagulants in healthy subjects (n = 8) showed that both the aggregating effect of ADP per se and the enhancing effect of adrenaline on ADP-induced aggregation (at EC50) were less influenced by acetylsalicylic acid when evaluated in hirudinized platelet-rich plasma (i.e. with physiological levels of extracellular calcium) as compared with citrated platelet-rich plasma.

5. It is concluded that acetylsalicylic acid treatment slightly attenuates the proaggregatory effect of high physiological concentrations of adrenaline in vitro. The impact of acetylsalicylic acid in vitro is, however, strongly dependent on the anticoagulant used, and is significantly weaker when evaluated in a medium with normal extracellular calcium levels (i.e. hirudin) than in a medium with low levels of extracellular calcium (citrate). Thus, acetylsalicylic acid may be a weak antagonist of catecholamine-induced platelet activation in vivo.
Cell Membrane Microviscosity and Ca2+-Mg2+-ATPase Activity do Not Contribute to Hypertension in the Spontaneously Hypertensive Rat Model
Authors: Norman Robert I , Achall Navtej
Published: August 2015

1. The relationships between systolic blood pressure and altered erythrocyte Ca2+-Mg2+-ATPase activity and membrane microviscosity were assessed in membranes prepared from 20-week-old female Wistar-Kyoto normotensive and spontaneously hypertensive rats obtained from two different sources (Charles River and Harlan OLAC) and a second filial (F2) generation derived from a cross between Wistar-Kyoto rats and spontaneously hypertensive rats from one source (Charles River).

2. Spontaneously hypertensive rats from both sources had systolic blood pressures significantly higher than those of Wistar-Kyoto animals (P <0.05; 151 + 4 and 110 + 3 mmHg, Charles River; 155 + 4 and 122 + 4 mmHg, Harlan OLAC). The systolic blood pressures for the F2 rat population ranged between 73 and 168 mmHg.

3. Ca2+-Mg2+-ATPase activity was measured as ATP-dependent 45Ca2+ uptake into inside-out vesicles and microviscosity assessed by the measurement of polarization anisotropy of membrane incorporated fluorescent probes including 1,6-diphenyl-1,3,5-hexatriene, trimethylamino-1,6-diphenyl-1,3,5-hexatriene and a series of anthroyloxy fatty acids.

4. Contrary to previous studies, no relationship between adult systolic blood pressure and erythrocyte Ca2+-Mg2+-ATPase activity or general or localized membrane microviscosity was indicated by the comparison of spontaneously hypertensive and Wistar-Kyoto animals or in the analysis of the F2 rat population.

5. These results suggest that Ca2+-Mg2+-ATPase activity and membrane microviscosity are causally unrelated to hypertension in these animals. On the assumption that biophysical properties of the erythrocyte membrane reflect those of smooth muscle, our results suggest that membrane alteration does not play a significant role in the pathogenesis of hypertension in the spontaneously hypertensive rat model.
Physiological Determinants of Inspiratory Effort Sensation during CO2 Rebreathing in Normal Subjects
Authors: Clague J. E. , Carter J. , Pearson M. G. , Calverley P. M. A.
Published: August 2015

1. The physiological basis of inspiratory effort sensation remains uncertain. Previous studies have suggested that pleural pressure, rather than inspiratory muscle fatigue, is the principal determinant of inspiratory effort sensation. However, only a limited range of inspiratory flows and breathing patterns have been examined. We suspected that inspiratory effort sensation was related to the inspiratory muscle tension-time index developed whatever the breathing pattern or load, and that this might explain the additional rise in sensation seen with hypercapnia.

2. To investigate this we measured hypercapnic re-breathing responses in seven normal subjects (six males, age range 21–38 years) with and without an inspiratory resistive load of 10 cm H2O. Pleural and transdiaphragmatic pressures, mouth occlusion pressure and breathing pattern were measured. Diaphragmatic and ribcage tension-time indices were calculated from these data. Inspiratory effort sensation was recorded using a Borg scale at 30s intervals during each rebreathing run.

3. Breathing pattern and inspiratory pressure partitioning were unrelated to changes in inspiratory effort sensation during hypercapnia. Tension-time indices reached pre-fatiguing levels during both free breathing and inspiratory resistive loading.

4. Stepwise multiple regression analysis using pooled mechanical, chemical and breathing pattern variables showed that pleural pressure was more closely related to inspiratory effort sensation than was transdiaphragmatic pressure. When converted to tension-time indices, ribcage tension-time index was the major determinant of inspiratory effort sensation during loaded rebreathing, but partial pressure of CO2 was an important independent variable, whereas during unloaded rebreathing partial pressure of CO2 was the most important determinant of inspiratory effort sensation.

5. These results suggest that the pattern of inspiratory pressure partitioning and inspiratory flow rate have little influence on inspiratory effort sensation during CO2 stimulated breathing. The close association between inspiratory effort sensation and ribcage tension-time index, an index of inspiratory muscle work, suggests that inspiratory effort sensation may forewarn of potential inspiratory muscle fatigue. Changes in PaCO2 have a small independent effect on respiratory perception.
Agonist-Induced Desensitization of β-Adrenoceptors of Bovine Bronchial Epithelial Cells
Authors: NoGami M. , Romberger D. J. , Rennard S. I. , Toews M. L.
Published: August 2015

1. Cultured bovine bronchial epithelial cells express a large number of β-adrenoceptors of the β2 subtype which are coupled to activation of adenylate cyclase and synthesis of cyclic AMP. The mechanisms involved in agonist-induced desensitization of β-adrenoceptor function in these cells were investigated.

2. Preincubation of cells with the β-adrenoceptor agonist isoprenaline induced a rapid desensitization of adenylate cyclase activity stimulated by isoprenaline (40% at 30 min) with little or no decrease in forskolin stimulation or in the number of β-adrenoceptors detected by radioligand binding, indicating that uncoupling of β-adrenoceptors from adenylate cyclase had occurred.

3. Uncoupling of β-adrenoceptors from the stimulatory guanine-nucleotide-binding protein Gs was indicated by the loss of GTP effects on agonist competition for radioligand binding. Results from subcellular fractionation by sucrose density gradient centrifugation suggest that rapid internalization or sequestration of β-adrenoceptors occurred along with the desensitization.

4. Preincubation with isoprenaline for longer times led to a marked decrease in total receptor number (85% at 18 h), indicating that receptor down-regulation also occurs. Recovery of receptors after down-regulation was prevented by cyclobeximide and by actinomycin D, suggesting that degradation of both receptor protein and receptor mRNA may be involved in down-regulation.
Haemodynamks of Recovery after Strenuous Exercise in Physically Trained Hypertensive and Normotensive Subjects
Authors: Casiglia Edoardo , Palatini Paolo , Bongiovi Stefano , Mario Luca , Colangeli Giovanna , Ginocchio Giuliana , Pessina Achille C.
Published: August 2015

1. Central and peripheral post-exercise haemo-dynamics were studied in 18 physically trained male subjects (10 hypertensive and eight normotensive) engaging in sports activities for 3–5 h/week. After a preliminary multistage bicycle ergometric test to evaluate their maximal oxygen consumption and anaerobic threshold, they underwent prolonged exercise at anaerobic threshold in the semi-supine position at 30% grade until exhaustion (mean duration 60.0 + 16.7 min in the normotensive subjects and 61.0 + 5.7 min in the hypertensive subjects, not significant). During the recovery time, intra-arterial blood pressure, echocardiographic cardiac output and indium-gallium strain-gauge plethysmographc peripheral flow were measured, and total, forearm and leg peripheral resistances were calculated respectively from mean blood pressure/cardiac output and mean blood pressure/peripheral resistance.

2. Systolic blood pressure was decreased during the entire recovery period in comparison with the baseline values (−8.4 mmHg, −43.8 mmHg and −39.7 mmHg at the 1st, 5th and 10th min in the hypertensive subjects, P = 0.001, P = 0.0001 and P = 0.0001 respectively; −18.8, −25.5 and −24.1 mmHg in the normotensive subjects, not significant, P = 0.01 and P = 0.01, respectively) without any significant difference between the two groups, whereas the reduction in diastolic blood pressure was not statistically significant. Peripheral flow increased and peripheral resistance decreased in parallel in the forearm and the leg and showed similar trends in the hypertensive subjects and the normotensive subjects. The increase in cardiac output and left ventricular ejection fraction and the decrease in total resistance were also similar in the two groups.

3. In conclusion, after long-lasting strenuous leg exercise central and peripheral haemodynamics vary to the same degree in hypertensive and normotensive trained subjects. Peripheral haemodynamics (similar in the leg and the arm in both groups) closely reflect systemic haemodynamics. The blood pressure reduction observed in the recovery period is totally due to the fall in systemic vascular resistance, while cardiac output is increased.
Rates of Change in Peak Expiratory Flow and in Diurnal Variation in Peak Flow in Patients Recovering from Acute Severe Asthma
Authors: Packe G. E. , Freeman W. , Cayton Ruth M.
Published: August 2015

1. The rates of change in mean peak expiratory flow and in diurnal variation in peak flow were compared in 14 patients recovering from acute severe asthma.

2. Peak expiratory flow was measured on hospital admission, and at 6-hourly intervals for the next 3 weeks.

3. Diurnal variation in peak flow was assessed by measuring the following: amplitude (the highest minus the lowest peak expiratory flow during any given 24 h period), amplitude % mean (the highest minus the lowest peak expiratory flow during any given 24 h period divided by the mean peak expiratory flow over that period) and residual amplitude (the maximum variation about the mean peak expiratory flow during any given 24 h period).

4. Plots of diurnal variation in peak flow and peak expiratory flow against time were constructed for each patient. To enable comparison of changes in peak expiratory flow and diurnal variation in peak flow the data were transformed.

5. The rate of change for mean peak expiratory flow and for the three measures of diurnal variation in peak flow was assessed by fitting an exponential function to each set of data, and calculating the slope of the exponential curve halfway through the period of observation (10.5 days).

6. Median (range) slope for peak expiratory flow was 0.055 (0-2.57). The comparable value for amplitude was −3.15 (−1.27 to −4.22) (absolute median values compared, P = 0.0029), for amplitude % mean was −1.87 (−0.18 to −5.95) (P = 0.012) and for residual amplitude was −1.43 (−0.62 to −3.09) (P = 0.033).

7. Diurnal variation in peak flow therefore takes longer to reach a stable value than does mean peak expiratory flow. We conclude that the magnitude of diurnal variation in peak flow during recovery from an acute attack of asthma is not governed exclusively by mean airway calibre.
Nitrogen Homoeostasis in man: Influence of Protein Intake on the Amplitude of Diurnal Cycling of Body Nitrogen
Authors: Price Gill M. , Halliday David , Pacy Paul J. , Quevedo Marcelo R. , Millward D. Joe
Published: August 2015

1. The diurnal nature of nitrogen (N) homoeostasis was investigated in adults fed increasing protein intakes. N balance was estimated during a 48 h period of consecutive 12 h periods of feeding hourly meals and fasting, after 12 days of adaptation to diets containing 0.36 +0.01, 0.77 + 0.03, 1.59 +0.08 and 2.31 +0.65 g of protein day−1 kg−1. N losses were determined from measured urinary N excretion corrected for changes in the body urea pool, and estimated faecal and miscellaneous losses. [13C] Leucine and [2H5]phenylalanine balances were measured during a primed, continuous infusion of the two amino acids during the fasting and feeding phase on the second day.

2. Increasing fasting N losses were observed (47 +7, 60+6, 95+15 and 140+36 mg day−1 kg−1) on the four intakes, with corresponding increasing fed gains of 8.2+3.9, 40.2+7.1, 112+24 and 180+ 56 mg day−1 kg−1.

3. Increasing fed-state amino acid gains with increasing protein intake were observed with both [13C]leucine and [2H5]phenylalanine, whereas increasing fasting amino acid losses were confirmed with [13C]leucine.

4. The N equivalent of the leucine oxidation rate was mostly in the range of 10–50% lower than expected from the N excretion rates. This may reflect the timing of the amino acid balance measurements and non-uniform rates of gain and loss throughout the diurnal cycle.

5. We conclude on the basis of both N and amino acid balances that the amplitude of the diurnal cycling of body protein N in human adults increases with increasing dietary protein intake. Thus one component of the protein requirement for N balance reflects a demand for repletion of fasting losses which increases with increasing habitual protein intake.
Abnormal Erythrocyte and Renal Frusemide-Sensitive Sodium Transport in Idiopathic Calcium Nephrolithiasis
Authors: Baggio Bruno , Gambaro Giovanni , Marchini Francesco , Vincenti Massimo , Ceolotto Giulio , Pessina Achille C. , Semplicini Andrea
Published: August 2015

1. Anomalous transmembrane anion transport has been observed in erythrocytes of patients with idiopathic calcium nephrolithiasis.

2. To verify whether cation transport is also abnormal, we investigated the frusemide-sensitive Na+ efflux from Na+-loaded erythrocytes and the natriuretic response to acute intravenous frusemide administration in calcium oxalate renal stone formers.

3. Frusemide administration induced a statistically significant smaller increase in the fractional excretion of Na+ in patients than in control subjects. Abnormal kinetic properties of erythrocyte Na+-K+-2Cl− co-transport were observed in approximately 60% of stone formers. The Km for Na+ of Na+-K+-2Cl− co-transport correlated with urinary Ca2+ excretion.

4. The abnormal kinetic properties of Na+-K+-2Cl− co-transport may be relevant for stone formation, hampering renal Ca2+ reabsorption in the distal nephron and determining critical physicochemical conditions for calcium/oxalate crystallization.
Albumin Excretory Rate in Normal and Hypertensive Pregnancy
Authors: Brown Mark A. , Wang Min-Xia , Buddle Megan L. , Carlton Mark A. , Cario Gregory M. , Zammit Vivienne C. , Whitworth Judith A.
Published: August 2015

1. The purpose of this study was to determine whether the 24 h urinary albumin excretory rate was increased in the third trimester of normal pregnancy or in pregnant women with hypertension who had 24 h urinary total protein excretion within the normal range.

2. Twenty-four hour urinary creatinine and albumin excretions were determined prospectively in 26 non-pregnant and 115 pregnant women in their third trimester (40 in normal pregnancy, 38 with mild pre-eclampsia, 20 with severe pre-eclampsia, 17 with essential hypertension) in whom urinary total protein excretion was normal. Both the urinary albumin excretion rate and the urinary albumin/creatinine ratio were compared among the groups. The clearance of albumin relative to that of creatinine was also calculated in the hypertensive women and in 14 of the non-pregnant women and nine of the normal pregnant women.

3. The twenty-four hour urinary albumin excretion rate was similar in non-pregnant [8(5–10) mg/day; median (interquartile range)] and normal pregnant [7(6–10) mg/day] women. Women with essential hypertension [6(4–16) mg/day] and mild pre-eclampsia [7(4–10) mg/day] had a urinary albumin excretion rate similar to that of normal pregnant women. Women with severe pre-eclampsia had an urinary albumin excretion rate increased [13(7–32) mg/day] compared with other groups (P < 0.05). The clearance of albumin relative to that of creatinine was elevated significantly only in women with severe pre-eclampsia compared with normal pregnant women (0.00054 versus 0.00012; P < 0.05). Blood pressures were similar among all hypertensive groups. The upper limit of the urinary albumin excretion rate was 20 mg/day in normal pregnant women, similar to that in non-pregnant women.

4. Urinary albumin excretion is unchanged in the third trimester of normal pregnancy, but is increased in women with features of severe pre-eclampsia who have normal total urinary protein excretion. This is not fully explained by a reduction in glomerular filtration rate nor by different systemic blood pressures, and probably reflects enhanced glomerular capillary permeability, possibly with altered maximum renal tubular reabsorption capacity for albumin.
Role of Cardiorespiratory Abnormalities, Smoking and Dive Characteristics in the Manifestations of Neurological Decompression Illness
Authors: Wilmshurst Dr Peter , Davidson Craig , O'Connell Geraldine , Byrne Christopher
Published: August 2015

1. Blind analysis of contrast echocardiograms to detect intracardiac shunts, blind analysis of lung function tests for evidence of small airways disease, smoking history and dive characteristics were examined in an attempt to explain neurological symptoms that occurred within 5 min of surfacing from unprovocative dives.

2. Pulmonary abnormalities were significantly more frequent in those divers without intracardiac shunts (50%) than in those with shunts (0%). Smoking was more common in those divers without shunts (55% versus 15%), although this just failed to reach conventional significance levels. Divers without shunts experienced cerebral rather than spinal symptoms after significantly shallower dives with lower tissue nitrogen loads. Depths of dives, tissue nitrogen loads and clinical manifestations in those divers without shunts were similar to the findings in divers who had symptoms after rapid ascents. Despite conservative dive profiles, clinical manifestations in divers with shunts resembled those observed after missed decompression stops.

3. The findings suggest that occult lung disease, and probably smoking, increase the risk of neurological symptoms, even after unprovocative dives, and the similarity of the dive profiles and clinical manifestations to cases with rapid ascents suggest that pulmonary barotrauma and arterial gas embolism are responsible. In divers with intracardiac shunts the different dive profiles and clinical manifestations imply that there is another mechanism, involving different tissue and bubble nitrogen kinetics resulting in venous gas liberation and peripheral amplification in embolized tissues, rather than paradoxical embolism per se.