bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of lipoproteins from pre-eclamptic women on umbilical endothelial cell 6-oxo-prostaglandin F1α and endothelin 1 synthesis, and nitric oxide synthase 3 mRNA expression
Authors: BARDEN A. , BEILIN L. J. , BOTH K. , RITCHIE J. , LEEDMAN P. , WALTERS B. N. , MICHAEL C. A.
Published: August 2015

In order to evaluate whether lipid abnormalities may contribute to endothelial dysfunction in pre-eclampsia, the present study examined the in vitro effects of very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL), isolated from women with pre-eclampsia and matched controls, on the endothelial synthesis of 6-oxo-prostaglandin F1α (6-oxo-PGF1α; a metabolite of prostacyclin) and endothelin 1, and on the expression of nitric oxide synthase 3 (NOS3) mRNA. VLDL, LDL and HDL cholesterol were isolated from 20 pre-eclamptic and 20 age- and gestation-matched normal pregnant women. The lipoproteins (50 μg/ml) and lipoprotein-free control plasma were incubated for 1, 3 and 6 h at 37 °C with a human umbilical endothelial cell line. The synthesis of 6-oxo-PGF1α and endothelin 1, and NOS3 mRNA expression, were measured at each time point. VLDL from pre-eclamptic women stimulated endothelial cell 6-oxo-PGF1α synthesis to a lesser extent than that from normal pregnant women (P< 0.05). LDL from women with pre-eclampsia also stimulated 6-oxo-PGF1α synthesis to a lesser extent than LDL from normal pregnant women, but the effect was less sustained. The effect of HDL from women with pre-eclampsia on 6-oxo-PGF1α synthesis was similar to that of HDL from normal pregnant women. The pre-incubation levels of lipid peroxides in VLDL and LDL were not different between the normal pregnant and pre-eclamptic women, and cannot account for the decrease in 6-oxo-PGF1α synthesis. VLDL, LDL and HDL from women with pre-eclampsia did not affect endothelial cell synthesis of endothelin 1 or expression of NOS3 mRNA differently from lipoproteins from normal pregnant women. This study suggests that VLDL, and to a lesser extent LDL, from women with pre-eclampsia could potentially contribute to the reduced systemic 6-oxo-PGF1α synthesis observed in the pre-eclamptic syndrome.
Time course of changes in serum glucose, insulin, lipids and tissue lipase activities in macrosomic offspring of rats with streptozotocin-induced diabetes
Authors: MERZOUK H. , MADANI S. , CHABANE SARI D. , PROST J. , BOUCHENAK M. , BELLEVILLE J.
Published: August 2015

The aim of this investigation was to determine the time course of changes in serum glucose, insulin and lipid levels, as well as lipid and protein content and lipolytic activities in insulin target organs (liver, adipose tissue and muscle), in macrosomic offspring of streptozotocin-induced mildly hyperglycaemic rats. Food intake and nutritional efficiency were also evaluated. Mild hyperglycaemia in pregnant rats was induced by intraperitoneal injection of streptozotocin (40 mg/kg body weight) on day 5 of gestation. Control pregnant rats were injected with citrate buffer. At birth, macrosomic pups (birth weight > 1.7 S.D. greater than the mean value for the control pups) had higher serum insulin, glucose and lipid levels than control pups. These macrosomic rats maintained accelerated postnatal growth combined with high adipose tissue weight up to 12 weeks of age. These rats were not hyperphagic; however, they had higher food efficiency and fat storage capacity with higher adipocyte lipoprotein lipase activity, which contributed to persisting obesity. Hepatic lipase activity was increased in macrosomic rats at all ages. Moreover, macrosomia was associated with metabolic disturbances that varied according to age and sex. After 1 month, several alterations observed at birth had disappeared. Serum glucose, insulin and lipid levels in male and female macrosomic rats became similar to those of their respective controls. At 2 months of age, hepatic and serum triacylglycerol levels were higher in macrosomic females than in controls. By 3 months, macrosomic rats (both males and females) had developed insulin resistance with hyperinsulinaemia, hyperglycaemia, and higher serum and hepatic lipids. In conclusion, macrosomia was associated with alterations in glucose and lipid metabolism through to adulthood. It should be considered as an important potential risk factor for obesity and its metabolic complications.
Plasma-volume contraction and exercise-induced hypoxaemia modulate erythropoietin production in healthy humans
Authors: ROBERTS D. , SMITH D. J. , DONNELLY S. , SIMARD S.
Published: August 2015

This study examined exercise-induced hypoxaemia (EIH) and plasma volume contraction as modulators of serum erythropoietin (Epo) production. Five athletes cycled for 3 min at supra-maximal power outputs, at each of two different elevations (1000 m and 2100 m). Five subjects were exposed to normobaric hypoxia (FIO2 = 0.159), seven subjects underwent plasmapheresis to reduce plasma volume and eight subjects were time controls for Epo levels. Oxyhaemoglobin saturation was significantly reduced during exercise and during normobaric hypoxia. The time period of haemoglobin oxygen saturation < 91% was 24±29 s (mean±S.D., n = 5) for exercise at 1000 m, 136±77 s (mean±S.D., n = 5) for exercise at 2100 m and 178±255 s (mean±S.D., n = 5) with resting hypoxic exposure. However, significantly increased serum Epo levels were observed only following exercise (24±3%; mean±S.D., n = 5 at 1000 m and 36±5%; mean±S.D., n = 5 at 2100 m). Volume contraction also resulted in increased serum Epo (35±6%; mean±S.D., n = 7) in spite of a significant rise in haematocrit of 2.2%. Despite similar degrees of arterial desaturation, only the hypoxaemia induced by exercise was associated with an increase in serum Epo. This finding indicates that other factors, in addition to hypoxaemia, are important in modulating the production of Epo in response to exercise. Volume depletion in the absence of exercise resulted in increases in Epo levels that were comparable with those observed in response to exercise. The paradoxical responses of the increased haematocrit and the increase in Epo in subjects undergoing plasmapheresis suggests that plasma volume may also modulate the production of Epo.
Venous endothelin receptor function in patients with chronic heart failure
Authors: LOVE Michael P. , HAYNES William G. , WEBB David J. , MCMURRAY John J. V.
Published: August 2015

Cardiac preload reduction through venodilatation is beneficial in chronic heart failure. The recent development of endothelin receptor antagonists for possible therapeutic use in heart failure has hastened the need for a clearer understanding of the venoconstrictor actions of endothelin-1 in this disease. Two main subtypes of endothelin receptor, ETA and ETB, exist in human blood vessels. We studied the venoconstrictor effects of endothelin-1 (a non-selective ETA and ETB agonist) and sarafotoxin S6c (a selective ETB agonist) in vivo in patients with chronic heart failure and in age-matched healthy controls. On separate days at least 1 week apart, locally active doses of endothelin-1 or sarafotoxin S6c were infused into a suitable dorsal hand vein for 1 h, and the venous internal diameter was measured using a displacement technique. Venoconstriction in response to endothelin-1 was significantly blunted in heart failure patients compared with controls (26±7% and 51±6% peak reduction in vein calibre respectively; P = 0.013). Venoconstriction to sarafotoxin S6c was similar in heart failure patients and controls (17±5% and 17±4% peak reduction in vein calibre respectively). Both ETA and ETB receptors mediate venoconstriction in healthy subjects and in patients with chronic heart failure. Optimal inhibition of the venoconstrictor effects of endothelin-1 in chronic heart failure may therefore require administration of an antagonist with ETA- and ETB-receptor-blocking properties. Chronic heart failure may be associated with a selective decrease in venous ETA receptor sensitivity, but further studies are required to clarify the functional significance of this observation.
Calcium oxalate crystallization kinetics studied by oxalate-induced turbidity in fresh human urine and artificial urine
Authors: KAVANAGH J. P. , JONES L. , RAO P. N.
Published: August 2015

We have studied the kinetics of oxalate-induced turbidity in fresh human urine and artificial urine. Assays are performed in 96-well plates, which allows many oxalate concentrations to be studied, repeatedly, in a short time. The metastable limit is defined in terms of the lowest oxalate concentration that gives a rate of change of attenuance significantly greater than the control. Interpretation of rates above this limit is based on ln/ln plots of initial rates against added oxalate concentration. This approach has a good theoretical basis, is well supported by our results and gives a turbidity rate index that is related to the product of the growth rate constant and a factor relating to the number and characteristics of the heteronuclei responsible for initiation of crystallization. This interpretation is posited upon the assumptions that second-order crystallization kinetics occur in unseeded urine when supersaturation exceeds the metastable limit and that aggregation during the initial phase of crystallization does not significantly contribute to changes in turbidity. Metastable limits of urine from healthy volunteers corresponded to a calcium oxalate supersaturation ratio of approx. 10. The turbidity rate index was higher in human urine than in artificial urine. The metastable limit, based on either oxalate concentration or supersaturation, for induction of calcium oxalate crystallization in normal human urine is higher than is likely to be found in normal subjects in vivo. The shape of the relationship between the metastable limit (based on oxalate concentration) and calcium concentration emphasizes the benefit of achieving a low urine calcium concentration. Comparison of the turbidity rate indices for human and artificial urine suggests that the role of nucleation promoters is more dominant than that of growth inhibitors.
Age-related changes in microvascular permeability: a significant factor in the susceptibility of children to shock?
Authors: GAMBLE J. , BETHELL D. , DAY N. P. J. , LOC P. P. , PHU N. H. , GARTSIDE I. B. , FARRAR J. F. , WHITE N. J.
Published: August 2015

During studies of the pathogenesis of dengue shock syndrome, a condition largely confined to childhood and characterized by a systemic increase in vascular permeability, we observed that healthy controls, age-matched to children with dengue shock syndrome, gave high values of filtration capacity (Kf), a factor describing vascular permeability. We hypothesized that Kf might be age dependent. Calf Kf was studied in 89 healthy Vietnamese subjects aged 5 to 77 years. The Kf was highest in the youngest children [7.53 (1.96–15.46) KfU; median (range); where the units of Kf, KfU = ml·min-1·100 ml-1·mmHg-1]. Values were 3- to 4-fold lower towards the end of the second decade [4.69 (1.91–7.06) KfU]. Young mammals are known to have a larger microvascular surface area per unit volume of skeletal muscle than adults. During development the proportion of developing vessels is greater. Moreover, the novel microvessels are known to be more permeable to water and plasma proteins than when mature. These factors may explain why children more readily develop hypovolaemic shock than adults in dengue haemorrhagic fever and other conditions characterized by increased microvascular permeability.
Cytochrome P450 metabolites of arachidonic acid may be important mediators in angiotensin II-induced vasoconstriction in the rat mesentery in vivo
Authors: CHU Z. M. , CROFT K. D. , KINGSBURY D. A. , FALCK J. R. , REDDY K. M. , BEILIN L. J.
Published: August 2015

We have investigated the role of cytochrome P450 (CYP-450) metabolites of arachidonic acid in the modulation of vascular reactivity to angiotensin II in vivo using an in situ blood-perfused mesenteric preparation in anaesthetized spontaneously hypertensive rats (SHR). Miconazole, a non-selective inhibitor of CYP-450 that inhibits both hydroxylation and epoxidation, substantially suppressed mesenteric vasoconstrictor responses to angiotensin II in SHR, but had no effect on responses to noradrenaline or sympathetic nerve stimulation. In normotensive Wistar–Kyoto (WKY) rats, miconazole caused only a modest suppression of vasoconstrictor responses to angiotensin II. N-Methylsulphonyl-12,12-dibromododec-11-enamide (DDMS), a new selective inhibitor of CYP-450 ω-hydroxylase activity, decreased mean intra-arterial blood pressure and significantly attenuated mesenteric angiotensin II-induced vasoconstrictor responses in SHR. Isolated mesenteric vessels were able to metabolize 14C-labelled arachidonic acid to hydroxyeicosatetraenoic acids (HETEs) in vitro, and this was substantially inhibited by DDMS. The results from the present studies combined with the existing evidence that angiotensin II stimulates the release of 20-HETE, a CYP-450 metabolite of arachidonic acid, suggest that CYP-450-derived HETEs may be important mediators in angiotensin II-induced vasoconstriction. However, the development of more sensitive assays for the detection in vivo of 20-HETE in mesenteric vessels would be required to confirm these findings.
Effects of prolonged hypobaric hypoxia on human skeletal muscle function and electromyographic events
Authors: CAQUELARD F. , BURNET H. , TAGLIARINI F. , CAUCHY E. , RICHALET J. P. , JAMMES Y.
Published: August 2015

This study tested the hypothesis that a prolonged decrease in arterial oxygen pressure in resting or contracting skeletal muscles alters their ability to develop force through an impairment of energy-dependent metabolic processes and also through an alteration of electrophysiological events. The experiment was conducted during a 32-day simulated ascent of Mt. Everest (8848 m altitude) (Everest III Comex '97), which also allowed testing of the effects of re-oxygenation on muscle function. Maximal voluntary contractions (MVCs) of the flexor digitorum, and static handgrips sustained at 60% of MVC, were performed by eight subjects before the ascent (control), then during the stays at simulated altitudes of 5000 m, 6000 m and 7000 m, and finally 1 day after the return to 0 m. The evoked muscle compound action potential (M-wave) was recorded at rest and during the manoeuvres at 60% of MVC. The changes in median frequency of electromyographic (EMG) power spectra were also studied during the contraction at 60% of MVC. In four individuals, transient re-oxygenation during the ascent allowed us to test the reversibility of hypoxia-induced MVC and M-wave changes. At rest, a significant decrease in M-wave amplitude was noted at 5000 m. This effect was associated with a prolonged M-wave conduction time at 6000 m and an increased M-wave duration at 7000 m, and persisted after the return to 0 m. Re-oxygenation did not modify the changes in M-wave characteristics. A significant decrease in MVC was measured only during the ascent (-10 to -24%) in the non-dominant forearm of subjects who underwent re-oxygenation; this intervention slightly improved muscle strength at 6000 m and 7000 m. During the ascent and after the return to 0 m, there was a significant reduction of the median frequency decrease throughout contraction at 60% of MVC compared with the EMG changes measured before the ascent. It is concluded that prolonged exposure to hypoxia slows the propagation of myopotentials and alters sensorimotor control during sustained effort. Re-oxygenation did not affect the hypoxia-induced EMG changes and had a modest influence on muscle strength.
Tumour necrosis factor-α gene expression and production in human umbilical arterial endothelial cells
Authors: NEUHAUS Thomas , TOTZKE Gudrun , GRUENEWALD Elisabeth , JUESTEN Hans-Peter , SACHINIDIS Agapios , VETTER Hans , KO Yon
Published: August 2015

Endothelial cells act as an interface between the blood and tissues, and are known to be involved in inflammatory processes. These cells are responsive to and produce different cytokines. Tumour necrosis factor-α (TNF-α) not only is one of the most important inflammatory peptides, but also can be induced by lipopolysaccharide (LPS). The focus of the present study was on TNF-α gene expression and production in human umbilical arterial endothelial cells (HUAEC), including the kinetics of this process. Interleukin-1α (IL-1α), LPS and TNF-α, which are all known to be elevated in septic shock, were used as stimulators at concentrations commonly found in patients with sepsis. Through the use of reverse transcriptase/PCR, immunohistochemical reactions and ELISA techniques, we showed that, in HUAEC, all three stimuli were able to induce gene expression and production of TNF-α. Furthermore, this induction by IL-1α, LPS and TNF-α occurred in a time- and concentration-dependent manner in these cells. TNF-α expression and production was induced by all three agents at concentrations commonly found in patients with sepsis. TNF-α mRNA was observed within 30 min regardless of the stimulus used, but the levels peaked at different times. Since it is well established that TNF-α is able to induce the synthesis of IL-1α in endothelial cells and, as shown in the present study, TNF-α and IL-1α are themselves able to induce the synthesis of TNF-α in endothelial cells, an autocrine potentiation of cytokine release in sepsis can be proposed. This situation could lead to a locally acting ‘vicious cycle’ which, when considered in addition to the known ability of TNF-α to induce apoptosis, could mean that various organs will be damaged, a condition associated with sepsis. Thus these results provide further evidence for the important role played by the endothelium in inflammation.
Localization of diuretic effects along the loop of Henle: an in vivo microperfusion study in rats
Authors: UNWIN R. J. , WALTER S. J. , GIEBISCH G. , CAPASSO G. , SHIRLEY D. G.
Published: August 2015

In order to clarify the effects on sodium reabsorption in the loop of Henle of methazolamide (a carbonic anhydrase inhibitor), chlorothiazide and the loop diuretics frusemide and bumetanide, superficial loops were perfused in vivo in anaesthetized rats and the individual diuretics were included in the perfusate. Differentiation between effects in the pars recta and in the thick ascending limb of Henle (TALH) was achieved by comparing responses to the diuretics when using a standard perfusate, designed to mimic native late proximal tubular fluid, and a low-sodium perfusate, designed to block net sodium reabsorption in the pars recta. With the standard perfusate, methazolamide caused decreases in sodium reabsorption (JNa) and water reabsorption (JV); with the low-sodium perfusate, a modest effect on JNa persisted, suggesting that carbonic anhydrase inhibition reduces sodium reabsorption in both the pars recta and the TALH. The effects of chlorothiazide were very similar to those of methazolamide with both the standard and low-sodium perfusates, suggesting that chlorothiazide also inhibits sodium reabsorption in the pars recta and TALH, perhaps through inhibition of carbonic anhydrase. With the standard perfusate, both frusemide and bumetanide produced the expected large decreases in JNa, but JV was also lowered. With the low-sodium perfusate, the inhibitory effects of the loop diuretics, particularly those of frusemide, were substantially reduced, while net potassium secretion was found. These observations indicate that a significant component of the effect of frusemide (and possibly of bumetanide) on overall sodium reabsorption is located in the pars recta, and that loop diuretics induce potassium secretion in the TALH.
Increased left atrial thrombin generation in mitral stenosis is not reflected in arterial prothrombin fragment 1+2 levels
Authors: PEVERILL Roger E. , HARPER Richard W. , GAN T. Eng , SMOLICH Joseph J.
Published: August 2015

A proportion of patients with mitral stenosis have increased left atrial thrombin generation, with elevated left atrial but normal peripheral venous levels of prothrombin fragment 1+2 (F1+2). Whether this pattern of left atrial and venous F1+2 levels is related to limited spillover of F1+2 from the left atrium into the systemic circulation, or to washout of increased left atrial F1+2 production into the arterial circulation with subsequent systemic clearance, is unclear. We examined the relationship between arterial and venous F1+2 levels in mitral stenosis patients without left atrial thrombus. The study group comprised 36 patients with either a normal (n = 29) or prolonged (n = 7) international normalized ratio (INR; a measure of clotting time) who were undergoing percutaneous balloon mitral valvuloplasty. Baseline arterial and venous blood samples were collected at the beginning of the valvuloplasty procedure, and left atrial and venous samples were collected after trans-septal puncture. The left atrial F1+2 level exceeded the corresponding venous level in patients with a normal INR (P < 0.03); however, baseline arterial and venous F1+2 levels were similar. Arterial and venous F1+2 levels were also similar in the subgroup of patients with evidence of a regional increase in left atrial thrombin generation, and were not different from arterial and venous F1+2 levels in patients without such an increase. Baseline arterial and venous F1+2 levels were both lower in the presence of a prolonged INR. Thus the pattern of increased left atrial but normal venous F1+2 levels in mitral stenosis is due to limited spillover from the left atrium into the systemic circulation.
Plasma soluble adhesion molecules and endothelium-dependent vasodilation in early human atherosclerosis
Authors: JOHN Stefan , JACOBI Johannes , DELLES Christian , SCHLAICH Markus P. , ALTER Ortrun , SCHMIEDER Roland E.
Published: August 2015

Levels of soluble cellular adhesion molecules are increased in patients with atherosclerosis, and have been found to predict coronary heart disease. Therefore these molecules have been suggested to represent laboratory markers for inflammation and activation of endothelial cells. Impaired endothelium-dependent vasodilation has been demonstrated to be an early marker of atherosclerosis. We hypothesized that soluble adhesion molecules are related to impaired endothelium-dependent vasodilation and may serve as an early marker of atherosclerosis. Patients (n = 52) with moderate and uncomplicated hypercholesterolaemia [low-density lipoprotein (LDL)-cholesterol 4.89±1.26 mmol/l] were compared with healthy controls (n = 43; LDL-cholesterol 2.44±0.79 mmol/l). Endothelium-dependent vasodilation of the forearm vasculature was assessed by intra-arterial infusion of acetylcholine (12 and 48 µg/min). Forearm blood flow was measured by venous occlusion plethysmography. Plasma concentrations of the soluble forms of ICAM-1 (intercellular cell adhesion molecule-1), VCAM-1 (vascular cell adhesion molecule-1) and E-selectin were measured by ELISA. Hypercholesterolaemic patients had impaired endothelium-dependent vasodilation in comparison with healthy controls (forearm blood flow after 48 µg/min acetylcholine: 21.3±10.6 and 30.4±16.3 ml·min-1·100 ml-1 respectively; P = 0.002). Plasma concentrations of soluble adhesion molecules were not different between hypercholesterolaemic patients and controls (ICAM-1, 196±56 and 180±38 ng/ml respectively; VCAM-1, 431±137 and 405±65 ng/ml respectively; E-selectin, 39±17 and 37±12 ng/ml respectively). Moreover, levels of soluble adhesion molecules were not correlated with endothelium-dependent vasodilation. Thus, in hypercholesterolaemic patients without clinical atherosclerosis, levels of soluble adhesion molecules were not elevated in comparison with healthy controls. In addition, these markers of endothelial inflammation were not related to impaired endothelium-dependent vasodilation. Our data indicate that measurement of levels of soluble adhesion molecules cannot replace assessment of endothelium-dependent vasodilation in detection of early hypercholesterolaemic atherosclerosis.
Prolongation of the QT interval in heart failure occurs at low but not at high heart rates
Authors: DAVEY P. P. , BARLOW C. , HART G.
Published: August 2015

Abnormal left ventricular structure and function as in, for example, left ventricular hypertrophy or chronic heart failure, is associated with sudden cardiac death and, when the ejection fraction is depressed, with prolongation of the QT interval. The dependence on heart rate of QT interval prolongation in these conditions, and the relationship of any abnormalities either to deranged autonomic nervous system function or to an adverse prognosis, has not been well studied. We therefore investigated (1) the dependence on heart rate of the QT interval, and (2) the relationship between both QT interval and the QT/heart rate slope and markers of adverse prognosis in these two conditions. The QT interval was measured at rest and during exercise in 34 subjects with heart failure, 16 subjects with left ventricular hypertrophy and 16 age-matched controls with normal left ventricular structure and function. QTc (corrected QT) intervals at rest were significantly longer in heart failure patients (471±10 ms) than in controls (421±6 ms) or in subjects with hypertrophy (420±6 ms) (P < 0.05). At peak exercise, despite the attainment of similar heart rates, the QT intervals no longer differed from each other, being 281±7 ms for controls, 296±11 ms in hypertrophy and 303±10 ms in heart failure (no significant difference). The QT/heart rate slope was significantly increased in heart failure [2.3±0.1 ms·(beats/min)-1] compared with controls [1.55±0.06 ms·(beats/min)-1] and hypertrophy [1.66±0.1 ms·(beats/min)-1] (P < 0.001). In left ventricular hypertrophy, despite animal data suggesting that QT interval prolongation should occur, no abnormalities were found in QT intervals at rest or during exercise. The QT/heart rate slope did not relate to any markers for an adverse prognosis, except that of prolongation of QT interval. Long QT intervals were associated principally with impairment of left ventricular systolic function. Our data emphasize the dynamic nature of the QT interval abnormalities found in heart failure.
Persistent, progressive hypophosphataemia after voluntary hyperventilation
Authors: PALEOLOGOS M. , STONE E. , BRAUDE S.
Published: August 2015

Hyperventilation (HV) and respiratory alkalosis are associated with hypophosphataemia, although the extent and duration of HV required to produce changes in serum phosphate levels are not known. We sought to characterize the effects of HV, with or without dextrose loading, on serum phosphate levels and other biochemical parameters. HV was monitored by controlling the end-tidal partial pressure of carbon dioxide (Petco2). The effect of dextrose was studied because infusion of a glucose load is known to promote a fall in serum phosphate via stimulation of glycolysis. Eight healthy volunteers were enrolled in four study protocols: (1) HV for 20 min to a Petco2 of 25–30 mmHg (mild); (2) HV for 20 min to a Petco2 of 15–20 mmHg (severe); (3) mild HV with intravenous dextrose loading, and (4) dextrose loading alone. Periodic measurements of serum phosphate, venous pH, serum 2,3-diphosphoglycerate (2,3-DPG) and other parameters were made. Serum phosphate fell during HV and continued to decline after cessation of HV. Dextrose loading alone caused a fall in serum phosphate that continued for at least 30 min after cessation of the infusion (P < 0.0002). HV combined with dextrose resulted in a greater decline in serum phosphate than either variable alone (P = 0.003). The maximal decline in serum phosphate occurred in severe HV, with a mean decrease of 0.38 mmol/l at 20 min after cessation of HV (P < 0.0001). Serum phosphate was still significantly lowered compared with baseline at 90 min after cessation of HV (P = 0.001). Other significant changes seen with HV included a decrease in serum glucose (P < 0.01), a decrease in serum potassium (P < 0.05) and an increase in venous pH (P < 0.007). Serum 2,3-DPG levels did not change significantly in any study protocol. Thus relatively mild acute HV produces significant changes in serum phosphate. In both mild and severe HV this effect is progressive after cessation of HV. This phenomenon has not been shown before, and may have significant clinical implications.
Sumatriptan reduces exercise capacity in healthy males: a peripheral effect of 5-hydroxytryptamine agonism?
Authors: MCCANN Gerald P. , CAHILL Helen , KNIPE Stephen , MUIR Douglas F. , MACINTYRE Paul D. , HILLS W. Stewart
Published: August 2015

5-Hydroxytryptamine (5-HT; serotonin) has been implicated in the perception of exercise-induced fatigue. Sumatriptan is a selective 5-HT1B/D receptor agonist which does not cross the blood–brain barrier. The aim of the present study was to determine the effect of sumatriptan on exercise capacity. Ten healthy male subjects (mean age 28.4±10.8 years) performed a maximal treadmill exercise test according to the Bruce protocol with expired gas analysis on two occasions. Either 6 mg of sumatriptan or placebo was administered subcutaneously in a randomized, double-blind, placebo-controlled, cross-over design. Exercise time was greater after placebo compared with sumatriptan [914 and 879 s respectively; 95% confidence interval (CI) of difference 12.1 s, 59.1 s; P = 0.008]. There was no significant effect on peak oxygen consumption (placebo, 50.6±6.3 ml·min-1·kg-1; sumatriptan, 51.7±7.6 ml·min-1·kg-1). Sumatriptan administration resulted in decreases in both heart rate (sumatriptan, 188±14 beats/min, placebo, 196±12 beats/min; 95% CI of difference 12.6, 2.6; P = 0.008) and respiratory exchange ratio (sumatriptan, 1.23±0.06; placebo, 1.26±0.07; 95% CI of difference 0.05, 0.01; P = 0.01) at peak exercise. There were no significant differences in blood pressure, heart rate or submaximal oxygen consumption between sumatriptan and placebo treatments at any stage of exercise. Thus sumatriptan reduces maximal exercise capacity in normal males. The failure to demonstrate any haemodynamic or cardiorespiratory effect suggests that sumatriptan enhances perception of fatigue by a peripheral mechanism affecting 5-HT modulation.
Internal carotid artery haemodynamics in women with polycystic ovaries
Authors: LAKHANI K. , CONSTANTINOVICI N. , PURCELL W. M. , FERNANDO R. , HARDIMAN P.
Published: August 2015

Although polycystic ovarian syndrome (PCOS) is associated with risk factors for cerebrovascular disease, the available evidence does not demonstrate increased stroke mortality, and it has been suggested that some protective mechanisms must be operating in these women. Haemodynamic changes have been demonstrated in the pelvic vessels and aorta in this syndrome, but there have been no studies of the cerebral circulation. Since insulin resistance is a central feature of PCOS, it is of interest that cerebral blood flow may be altered in diabetic subjects. The present study was designed to assess internal carotid artery haemodynamics in women with PCOS, asymptomatic women with polycystic ovaries (PCO women) and healthy controls. Mean internal carotid pulsatility index, measured using pulsed Doppler ultrasound under standardized conditions, was significantly lower in 35 PCOS and 15 PCO women than in the 18 controls. This was also shown on multiple regression analyses. Peak systolic velocity did not differ between groups. In view of the difficulty of interpreting pulsatility index in low-impedance vascular beds, the ‘back’ pressure was calculated and found to be lower in women with polycystic ovaries. This is the first demonstration of lower pulsatility index and back pressure (suggestive of reduced vascular tone) in the cerebral circulation of these women, independent of blood pressure, insulin resistance and other endocrine or metabolic factors. Changes in internal carotid haemodynamics may offset the risk of cerebrovascular disease commonly associated with polycystic ovaries.
Effects of ATP infusion on glucose turnover and gluconeogenesis in patients with advanced non-small-cell lung cancer
Authors: AGTERESCH H. J. , LEIJ-HALFWERK S. , VAN DEN BERG J. W. O. , HORDIJK-LUIJK C. H. , WILSON J. H. P. , DAGNELIE P. C.
Published: August 2015

Cancer cachexia is associated with elevated lipolysis, proteolysis and gluconeogenesis. ATP infusion has been found to significantly inhibit loss of body weight, fat mass and fat-free mass in patients with advanced lung cancer. The present study was aimed at exploring the effects of ATP on whole-body glucose turnover, alanine turnover and gluconeogenesis from alanine. Twelve patients with advanced non-small-cell lung cancer (NSCLC) were studied 1 week before and during 22–24 h of continuous ATP infusion. After an overnight fast, turnover rates of glucose and alanine, and gluconeogenesis from alanine, were determined using primed constant infusions of [6,6-2H2]glucose and [3-13C]alanine. Thirteen NSCLC patients and eleven healthy subjects were studied as control groups without ATP infusion. During high-dose ATP infusion (75 µg·min-1·kg-1), glucose turnover was 0.62±0.07 mmol·h-1·kg-1, compared with 0.44±0.13 mmol·h-1·kg-1 at baseline (P = 0.04). For gluconeogenesis a similar, but non-significant, trend was observed [baseline, 0.30±0.16 mmol·h-1·kg-1; during ATP, 0.37±0.13 mmol·h-1·kg-1 (P = 0.08)]. At lower ATP doses (37–50 µg·min-1·kg-1) these effects were not detected. The relative increase in glucose turnover during ATP infusion compared with baseline showed a significant correlation with the ATP dose (r = 0.58, P = 0.02). No change in alanine turnover was observed at any ATP dose. The results of this study indicate an increase in glucose turnover during high-dose ATP infusion compared with baseline levels. During high-dose ATP infusion, glucose turnover was similar to that during low-dose ATP infusion and to that in control NSCLC patients. Between ATP infusions, however, glucose turnover in patients treated with high-dose ATP was significantly lower than that in the low-dose and control NSCLC patients (P = 0.04 and P = 0.03 respectively), and similar to that in healthy subjects. This would suggest that repeated high-dose ATP infusions may inhibit glucose turnover between infusion periods.
Myocardial infarction with and without reperfusion in sheep: early cardiac and neurohumoral changes
Authors: CHARLES Christopher J. , ELLIOTT John M. , NICHOLLS M. Gary , RADEMAKER Miriam T. , RICHARDS Mark
Published: August 2015

There are few stable and reproducible large-animal models of chronic heart failure produced by ischaemic damage to the myocardium. Here we characterize a novel method of inducing myocardial damage in closed-chest sheep by catheter delivery of thrombogenic coils, and compare this with a newly described open-artery model of cardiac injury in sheep. Sham controls were compared with animals subjected to (a) 90 min of coronary artery occlusion/reperfusion by PTCA (percutaneous transluminal coronary angioplasty) balloon, and (b) permanent coronary artery occlusion induced by catheter delivery of thrombogenic coils (seven sheep/group). Both balloon occlusion/reperfusion and permanent coil occlusion resulted in well-defined anteroapical infarcts, as documented by ECG changes, significant rises in creatine kinase (both groups P < 0.001) and troponin-T (both groups P < 0.05), and post-mortem examination. Washout of enzymes was much more rapid in the reperfused group (P < 0.01). Infarction resulted in significant reductions in left ventricular (LV) ejection fraction (both groups P < 0.01) and regional wall abnormalities. Ejection fraction 7 days post-coil (21.3±4.2%) was significantly lower (P < 0.01) than that 7 days post-balloon (38.8±4.5%). Coil-induced infarction was associated with acutely reduced arterial pressure (P < 0.05), and increases in heart rate (P < 0.05), atrial pressures (P < 0.05), plasma brain natriuretic peptide levels (P < 0.05) and adrenaline levels (P < 0.05). Rises seen in plasma endothelin levels in sham controls were blunted in the coil group (P < 0.001). Haemodynamic changes were less marked in the balloon group. In conclusion, restriction of coronary artery occlusion to 90 min results in infarction, but less LV dysfunction with reduced early remodelling, compared with permanent occlusion. Acute changes in biochemical markers, haemodynamics, neurohormones and LV function confirm that these are excellent models of open- and closed-artery myocardial infarction leading to asymptomatic LV dysfunction.
Elevated circulating cardiotrophin-1 in heart failure: relationship with parameters of left ventricular systolic dysfunction
Authors: TALWAR S. , SQUIRE I. B. , DOWNIE P. F. , O'BRIEN R. J. , DAVIES J. E. , NG L. L.
Published: August 2015

Cardiotrophin-1 (CT-1) is a cytokine that has been implicated as a factor involved in myocardial remodelling. The objective of the present study was to establish the relationship between circulating levels of CT-1 and measures of left ventricular size and systolic function in patients with heart failure. We recruited 15 normal subjects [six male; median age 60 years (range 30–79 years)] and 15 patients [11 male; median age 66 years (range 43–84 years)] with a clinical diagnosis of heart failure and echocardiographic left ventricular systolic dysfunction (LVSD). Echocardiographic variables (left ventricular wall motion index, end-diastolic and -systolic volumes, stroke volume, fractional shortening) and plasma CT-1 levels were determined. In patients with LVSD [median wall motion index 0.6 (range 0.3–1.4)], CT-1 was elevated [median 110.4 fmol/ml (range 33–516 fmol/ml)] compared with controls [wall motion index 2 in all cases; median CT-1 level 34.2 fmol/ml (range 6.9–54.1 fmol/ml); P < 0.0001]. Log CT-1 was correlated with log wall motion index (r = -0.76, P < 0.0001), log left ventricular end-systolic volume (r = 0.54, P < 0.05), stroke volume (r = -0.60, P = 0.007) and log fractional shortening (r = -0.70, P = 0.001). In a multivariate model of the predictors of log wall motion index, the only significant predictor was log CT-1 (R2 = 56%, P = 0.006). This is the first assessment of the relationship between plasma CT-1 levels and the degree of LVSD in humans, and demonstrates that CT-1 is elevated in heart failure in relation to the severity of LVSD.
Analysis of the candidate genes responsible for non-syndromic cleft lip and palate in Japanese people
Authors: TANABE Atsuko , TAKETANI Shigeru , ENDO-ICHIKAWA Yoko , TOKUNAGA Rikio , OGAWA Yutaka , HIRAMOTO Michiaki
Published: August 2015

In order to assess the association of alleles for candidate genes with non-syndromic cleft lip and palate, DNA samples from 43 Japanese patients were compared with those from 73 control subjects with respect to the genes encoding transforming growth factor α (TGFα), TGFβ and γ-aminobutyric acid type A receptor β3 (GABRB3). The restriction fragment length polymorphisms of the 3′-non-coding region of the TGFα gene K-primer region were observed after digestion with NcoI and HinfI. Allele 4 was the most common among cases of cleft lip with or without cleft palate, whereas allele 2 was the most common among controls. A significant difference was found in this region between groups with cleft lip (with or without cleft palate) and controls (χ2 = 10.190; P = 0.017). Three alleles of the TGFβ2 gene were tested, and allele 2 was the most common in both cases and controls. The proportion of allele 2 in the case group was greater than that in the control group, showing a significant difference between cases of cleft lip (with or without cleft palate) and controls (χ2 = 19.208; P < 0.0001). No significant differences in variants of TGFβ3 or GABRB3 between case and control populations were observed. Thus it is concluded that TGF genes play a role in craniofacial development, and that alleles of TGFα or/and TGFβ2 are associated with cleft lip and cleft palate in Japanese populations.
Effects of sympathetic inhibition on exertional dyspnoea, ventilatory and metabolic responses to exercise in normotensive humans
Authors: GALLOWAY Stuart D. R. , VITO Giuseppe DE , McCLURE Sam , NIMMO Myra A. , McMURRAY John J. V.
Published: August 2015

Augmentation of circulating noradrenaline concentration stimulates ventilation during the initial stages of exercise and this is accompanied by an increased sensation of dyspnoea and exertion. This previous study [Clark, Galloway, MacFarlane, Henderson, Aitchison and McMurray (1997) Eur. Heart J. 18, 1829–1833] suggested a link between dyspnoea, which commonly limits exercise tolerance in heart failure patients, and high circulating noradrenaline concentration in these patients. The present study investigated this relationship further using sympathetic inhibition. Ten healthy normotensive males performed 10 min of submaximal cycling exercise at approx. 70% of maximal oxygen uptake per min (VċO2max) on three occasions one week apart. The first of these sessions was a familiarization session and the other two were experimental study days. On each of the study days, subjects attended the laboratory in the morning after an overnight fast and, following a resting blood sample, were administered placebo or moxonidine (0.4 mg) in a double blind cross-over design. After a 90-min absorption period, subjects undertook the exercise task. Blood was drawn, expired gas was analysed breath by breath, blood pressure, heart rate and ratings of perceived dyspnoea and exertion were obtained. Moxonidine treatment significantly reduced plasma noradrenaline concentration (P < 0.01), mean arterial pressure (P < 0.01), and blood glycerol concentration (P < 0.05), but no differences were observed in heart rate, the ventilatory response to exercise or subjective ratings of dyspnoea and exertion. This study indicates that reducing sympathetic activity does not affect ventilation, perceived dyspnoea or perceived exertion in normotensive males. Therefore it can be concluded that reducing sympathetic activity may not be an appropriate strategy to help reduce perceived dyspnoea.
T-cell recognition of discrete regions of the thrombolytic drug streptokinase
Authors: LAWLEY Wendy J. , FLETCHER Sue , SQUIRE Iain B. , WOODS Kent L. , HEWITT Colin R. A.
Published: August 2015

Streptokinase (SK) is a bacterial protein used clinically as a thrombolytic agent in humans. Administration of SK causes a rapid increase in the frequency of anti-SK T cells and the titre of specific anti-SK antibodies that, on subsequent administration of SK, may neutralize the activity of the drug or elicit allergic-type reactions. By locating and modifying the immunogenic T-cell epitopes within the SK protein, it is possible that an agent with reduced immunogenicity but equal efficacy may be produced. We have investigated the T-cell epitopes within SK using nine non-overlapping, recombinant peptide fragments of SK. We investigated the proliferative T-cell response of peripheral blood mononuclear cells obtained from patients before and 6 days after administration of SK for myocardial infarction. We also examined the response of cultured anti-SK T-cell lines derived from patients 6 days after treatment with SK. Before administration of SK, peripheral blood mononuclear cells from six of nine patients showed a proliferative response to SK. The response was significantly higher 6 days after administration of SK (P = 0.0004). Cultured T-cell lines showed similar proliferative responses to clinical-grade SK and recombinant SK. Marked differences in T-cell responses were apparent in response to each recombinant SK fragment (P = 0.04). The mean proliferative response exceeded background to only two peptides, peptide 2 (P = 0.04) and peptide 3 (P = 0.009). Peptide 3, representing amino acids 100–150 of mature SK, was recognized preferentially in the majority of assays. Marked variation in the T-cell response to SK following treatment with this agent was observed between subjects. Despite these differences, peptides 2 and 3 induced T-cell proliferation at a level significantly above background in the majority of subjects. These epitopes may represent a region of enhanced immunogenicity within SK.
Angiotensin-converting enzyme gene polymorphism and premature coronary heart disease
Authors: VAN BOCKXMEER Frank M. , MAMOTTE Cyril D. S. , BURKE Valerie , TAYLOR Roger R.
Published: August 2015

Since the initial report of the association of the deletion/insertion (D/I) polymorphism in the gene for angiotensin-converting enzyme (ACE) with myocardial infarction (MI), there has been considerable controversy. Some have found the D allele to be associated with MI, coronary heart disease (CHD) or other cardiac pathology, while others have not. In the present study 713 consecutive patients, < 50 years of age, documented prospectively with angiographic CHD (> 50% diameter stenosis of at least one coronary artery), with or without MI, were studied, along with 688 community control subjects, also < 50 years of age, selected randomly from the electoral rolls and without a history of CHD or MI. Genotyping was done by standard methods. Most of the subjects in both groups were Anglo–Celtic Caucasians (547 in the CHD group and 642 in the community group), and the report concerns primarily these subjects. ACE genotype distributions were not different between the Caucasian community control group and the CHD or the MI subgroups; the odds ratios and 95% confidence limits for the CHD group were 0.96 (0.73–1.27) for the D allele and 1.02 (0.80–1.31) for D homozygotes; for the MI group these values were 1.00 (0.83–1.20) and 0.99 (0.74–1.32) respectively. This negative result was supported in multivariate analysis accounting for conventional risk factors. There was a significant racial difference in ACE genotypes between Caucasians, Asians and Australian Aborigines in the CHD group (P < 0.001); for example, in this group, 158 of 540 (29%) Caucasians had the DD genotype compared with eight of 84 (10%) Aboriginals (P < 0.001) and six of 59 (10%) Asians (P = 0.002). Failure to account for such racial differences would have led to erroneous conclusions. In conclusion, we found no evidence that the D/I ACE gene polymorphism plays a role in the development of CHD or MI at an early age in a Western Australian Caucasian population. While this result refers uniquely to premature CHD and MI, and could be population specific, it is in general agreement with recent meta-analysis of the larger previous studies.
Effects of tumour necrosis factor-α and inhibition of protein kinase C on glucose uptake in L6 myoblasts
Authors: PATIAG Divina , GRAY Samuel , IDRIS Iskander , DONNELLY Richard
Published: August 2015

Clinical and experimental studies have implicated high circulating levels of the cytokine tumour necrosis factor-α (TNF-α) in the pathogenesis of insulin resistance, not only in obesity and diabetes, but also in clinical conditions associated with cachexia and sepsis. TNF-α impairs insulin-mediated glucose uptake in adipocytes, but because of lipolytic effects the interpretation of clinical studies and the extent to which TNF-α affects muscle insulin sensitivity are unclear. In addition, protein kinase C (PKC) has recently been implicated in the mechanism of TNF-α-induced insulin resistance. The present study investigated the effects of TNF-α and a PKC inhibitor (RO-318220) on basal and insulin-stimulated 2-[3H]deoxyglucose uptake in cultured L6 myoblasts. Reverse transcriptase–PCR analysis confirmed that L6 myoblasts express TNF-α receptors I and II (p60 and p80). Dose–response curves for glucose uptake were fitted to a quadratic function to derive CI-150 values (concentration of insulin required to increase glucose uptake by 50%). Incubation with TNF-α at 1 or 10 ng/ml for 24 h had no significant effect on basal glucose uptake, insulin sensitivity or maximal insulin responsiveness. CI-150 values (means±S.E.M.) were as follows: basal, 91.2±13 nM; 1 ng/ml TNF-α, 102±12 nM; and basal, 70.8±13 nM; 10 ng/ml TNF-α, 43.7±40 nM. PKC inhibition markedly attenuated glucose uptake, but there was no difference in insulin sensitivity with RO-318220 alone compared with RO-318220+TNF-α. In conclusion, although increased TNF-α expression and plasma concentrations have been implicated in the pathogenesis of insulin resistance in various clinical states, there is no evidence that TNF-α impairs insulin-stimulated glucose uptake in a skeletal-muscle-derived cell line.