bluuebunny/crossref_metadata_2025 huggingface dataset:
Haemodynamic and renal evolution of the bile duct-ligated rat
Authors: MARTÍNEZ-PRIETO Concepción , ORTÍZ M. Clara , FORTEPIANI Lourdes A. , RUIZ-MACIÁ Jose Antonio , ATUCHA Noemí M. , GARCÍA-ESTAÑ Joaquín
Published: August 2015

In the present study we have characterized the evolution of changes in systemic haemodynamics (thermodilution in conscious animals) and sodium balance (metabolic cages) in a model of liver cirrhosis induced by chronic bile duct ligation (BDL). Mean arterial pressure (BDL, 111.5±4.7 mmHg; sham-operated, 122.9±3.0 mmHg) and peripheral vascular resistance (BDL, 2.63±0.08 units; sham-operated, 2.93±0.09 units) were lower in BDL rats from day 12 after surgery and decreased progressively throughout the following days. Portal hypertension was evident earlier in BDL rats and was maintained throughout the study period. Cardiac index (BDL, 58.8±3.9 ml·min-1·100 g-1; sham-operated, 43.9±1.5 ml·min-1·100 g-1) and stroke volume (BDL, 147.2±12.7 ml·beat-1·100 g-1; sham-operated, 109.0±4.2 ml·beat-1·100 g-1) were significantly elevated in the BDL rats only from day 18 after surgery. There were no significant differences in sodium balance between the groups until day 16 after surgery, at which time BDL animals started to retain significantly more sodium than the controls. Sodium retention increased progressively, and at day 20 BDL rats had retained 0.7 mmol/100 g more than the control animals (accumulated retention: BDL, 2.2±0.2 mmol/100 g; sham-operated, 1.5±0.2 mmol/100 g). Plasma renin activity and aldosterone concentration were not elevated in the BDL animals at days 12, 16 or 20 after surgery. These data indicate that the BDL rat model shows early portal hypertension, peripheral vasodilation and arterial hypotension, several days before sodium retention is detectable, and in the absence of changes in plasma levels of renin and aldosterone. Overall, these data suggest that, in the BDL rat model, sodium retention is secondary to portal hypertension and peripheral vasodilation.
Effects of partial and total colectomy on mineral and acid–base homoeostasis in the rat: magnesium deficiency, hyperphosphaturia and osteopathy, in the presence of high serum 1,25-dihydroxyvitamin D but normal parathyroid hormone
Authors: CRONER R. , SCHWILLE P. O. , ERBEN R. G. , GEPP H. , STAHR K. , RÜMENAPF G. , PARTH R. , SCHEUERLEIN H.
Published: August 2015

The effects of colectomy on acid–base status, extra-osseous and bone minerals, calciotropic hormones and bone morphology have not yet been studied. To rectify this, groups of normally fed male rats were subjected to distal (n = 11), proximal (n = 12) or total (n = 12) colectomy. Sham-operated rats (n = 12) served as controls. At 112 (±2) days after colectomy the following changes were noted: (1) weight gain was delayed; (2) faecal excretion of calcium and phosphorus was normal, whereas that of magnesium was increased; (3) intestinal calcium secretion and absorption of calcium and phosphorus were normal, but magnesium absorption was decreased; (4) urinary excretion of magnesium was also decreased, that of phosphorus was increased, and that of pyridinium and deoxypyridinium tended to be high; (5) the serum levels of ionized magnesium, total calcium, 25-hydroxyvitamin D and parathyroid hormone were normal, while that of 1,25-dihydroxyvitamin D was markedly elevated; and (6) bone magnesium and phosphorus content were decreased, but bone calcium was normal, and thus the bone calcium/phosphorus ratio was high. These abnormalities were associated with moderate metabolic acidosis, as reflected by high urinary ammonium, low citrate and low total CO2, but normal blood gases. Significant structural abnormalities of bone were not detectable, but trabecular bone tended to show rarefication. Distal colectomy had the least effect, whereas proximal and total colectomies had a distinct effect, on these parameters. It is concluded that colectomy in the rat causes: (1) a syndrome of magnesium deficiency of intestinal origin, compensated metabolic acidosis, urinary phosphorus loss, and high circulating 1,25-dihydroxyvitamin D levels, with the degree depending on the extent of surgical resection; and (2) brittle bones, a feature characteristic of low bone magnesium and more generalized magnesium deficiency. The mechanisms leading to this syndrome are unknown, but altered tissue levels of magnesium and phosphorus may play a key role.
Abnormal thiol group modulation of sodium– lithium countertransport and membrane fluidity is associated with a disturbed relationship between serum triacylglycerols and membrane function in Type II diabetes
Authors: SENIOR P. A. , THOMAS T. H. , MARSHALL S. M.
Published: August 2015

In essential hypertension and diabetic nephropathy, sodium–lithium countertransport (Na–Li CT) is an inherited marker, subject to metabolic influences, of cardiovascular risk. Studies in Type II diabetes, taking clinical phenotypes as their starting point, are conflicting. We sought to identify Na–Li CT kinetic abnormalities in Type II diabetes, and only subsequently to seek relationships with clinical variables. Na–Li CT kinetics, membrane fluidity and their modulation by thiol proteins were measured in erythrocytes from 38 patients with Type II diabetes and in 16 normal control subjects. In untreated erythrocytes, Na–Li CT kinetics were similar. Thiol protein alkylation with N-ethylmaleimide generally caused both Vmax and Km to fall, but caused Km to rise in erythrocytes from 13 out of 38 diabetic subjects, whose native Km was low (P = 0.0013 compared with control). Vmax and serum triacylglycerol levels were related in normal controls (rs = 0.54, P = 0.038) and in diabetic subjects whose Km fell after N-ethylmaleimide (n = 25, rs = 0.62, P = 0.001). Where the Km rose after N-ethylmaleimide, Vmax and triacylglycerol levels were not related (n = 13, rs = -0.39, P = 0.183) and membrane fluidity did not increase after N-ethylmaleimide. However, these subgroups were indistinguishable in terms of blood pressure, albuminuria, glycaemia or lipid profiles. Thus abnormalities in the regulation of Na–Li CT and membrane fluidity by key thiol proteins, resembling those seen in essential hypertension and diabetic nephropathy, were apparent in one-third of subjects with Type II diabetes. Membrane abnormalities may indicate a common pathological mechanism. The prognostic significance of Na–Li CT kinetic abnormalities in Type II diabetes must now be confirmed.
The angiotensinogen gene 235T variant is associated with an increased risk of restenosis after percutaneous transluminal coronary angioplasty
Authors: VÖLZKE Henry , HERTWIG Sabine , RETTIG Rainer , MOTZ Wolfgang
Published: August 2015

The therapeutic benefit of percutaneous transluminal coronary angioplasty (PTCA) is limited by restenosis in 30–40% of patients. The underlying mechanisms are currently not well understood. Besides clinical and angiographic variables, genetic factors may be involved. In the present study, we investigated the associations between the angiotensinogen T174M and M235T, the angiotensin I-converting enzyme (ACE) I/D and the angiotensin II type 1 receptor A1166C gene polymorphisms and restenosis in 511 patients who had undergone successful PTCA (without stenting) and follow-up angiography. Clinical and angiographic variables were also considered as possible predictors of restenosis. Stenosis severity was estimated by visual inspection of the angiograms. Altogether, 160 patients had restenosis, as defined by a greater than 50% reduction in the diameter of the dilated segment at follow-up angiography compared with the findings immediately following angioplasty. There were significantly more carriers of the angiotensinogen 235T allele and more patients with the ACE DD genotype in the restenosis group than in the no restenosis group, but only the angiotensinogen 235T allele (and not the ACE DD genotype) remained significantly associated with restenosis following multifactorial analyses. No differences between the two groups were found with respect to the other gene polymorphisms. Patients who subsequently developed restenosis had a higher degree of stenosis and more severe lesions before PTCA, as well as less residual stenosis immediately after PTCA. We conclude that the angiotensinogen M235T gene polymorphism may be an independent predictor of restenosis after PTCA.
Effects of hyperglycaemia and hyperinsulinaemia on proximal gastric motor and sensory function in humans
Authors: VAN PETERSEN A. S. , VU M. K. , LAM W. F. , LAMERS C. B. H. W. , RINGERS J. , MASCLEE A. A. M.
Published: August 2015

During acute hyperglycaemia, gastric emptying is delayed and the compliance of the proximal stomach is increased significantly. It is not known whether the effect of hyperglycaemia on proximal gastric motor function in healthy volunteers results from endogenous hyperinsulinaemia. Therefore we studied the effects of acute hyperglycaemia and hyperinsulinaemia on proximal gastric function, measured using an electronic barostat. Eight healthy volunteers were studied on three separate occasions during: (a) normoglycaemia, (b) hyperglycaemic hyperinsulinaemic clamping, and (c) euglycaemic hyperinsulinaemic clamping. Gastric compliance was significantly (P < 0.01) increased during hyperglycaemia (44±5 ml/mmHg), and also during hyperinsulinaemia (38±4 ml/mmHg), compared with during normoglycaemia (31±3 ml/mmHg). During pressure distension, sensations of fullness were greater during hyperglycaemia and during hyperinsulinaemia compared with controls. At a set pressure of minimal distension pressure +2 mmHg, the intrabag volume was significantly higher during hyperglycaemia (292±36 ml; P < 0.05), but not during hyperinsulinaemia (161±35 ml), compared with during normoglycaemia (129±10 ml). Postprandial relaxation was significantly (P < 0.01) decreased during hyperglycaemia (93±64 ml) and hyperinsulinaemia (101±64 ml) compared with normoglycaemia (224±56 ml). Thus not only hyperglycaemia, but also hyperinsulinaemia, influences proximal gastric compliance, postprandial relaxation and symptom perception.
Aging reduces the responsiveness of coronary arteries from male Wistar rats to the vasodilatory action of testosterone
Authors: ENGLISH Kate M. , JONES Richard D. , JONES Hugh T. , MORICE Alyn H. , CHANNER Kevin S.
Published: August 2015

This study was performed to examine whether aging affects the vasodilatory effects of testosterone in the coronary arteries of male rats. Isolated coronary arteries from young mature (3–4 months) and elderly (22–26 months) male Wistar rats were studied in a wire myograph. Contractile function and endothelial function were assessed by measuring vasomotor responses to 10–100 mmol/l KCl, 0.1 mmol/l prostaglandin F2α (PGF2α) and 10 µmol/l acetylcholine. Sensitivity to the vasodilatory effects of testosterone was assessed by constructing dose–response curves to concentrations between 1 µmol/l and 1 mmol/l testosterone dissolved in water in vessels maximally preconstricted with PGF2α. The compliance characteristics of each vessel and serum testosterone levels from each animal were measured. Histological sections of myocardium were examined for differences in coronary artery morphology. Vessels from elderly animals were significantly more resistant to the vasodilatory effects of testosterone than vessels from young animals (P = 0.001 by analysis of covariance). Vessels from elderly animals were also significantly less compliant (7.32±0.43 µm/mN, compared with 10.99±1.52 µm/mN in young animals; P = 0.011), and the levels of circulating testosterone in elderly animals were lower, but not significantly so (2.04±0.63 nmol/l compared with 3.88±1.7 nmol/l; P = 0.32). Vessels from elderly animals were less contractile in response to KCl than those from young animals (P = 0.004 by analysis of covariance). There were no significant differences between the two groups in their responses to PGF2α or acetylcholine. Thus it is concluded that coronary arteries from elderly rats are significantly less sensitive to the vasodilatory effects of testosterone than those from young animals.
The impairment in endothelial function induced by non-esterified fatty acids can be reversed by insulin
Authors: LIND Lars , FUGMANN Andreas , BRANTH Stefan , VESSBY Bengt , MILLGÅRD Jonas , BERNE Christian , LITHELL Hans
Published: August 2015

Dyslipidaemia, with elevations of circulating triacylglycerols (triglycerides) and non-esterified (free) fatty acids, and hyperinsulinaemia are often found in the same subjects, the so-called ‘insulin resistance syndrome’. The present study aims to investigate how elevated levels of non-esterified fatty acids, hyperinsulinaemia and the combination of these factors affects endothelium-dependent vasodilatation (EDV). Ten volunteers were examined on two occasions. Intralipid® (plus heparin) or saline (0.9% NaCl) was infused for 4 h. During the final 2 h, euglycaemic hyperinsulinaemia (80±4 m-units/l) was imposed. EDV and endothelium-independent vasodilatation were evaluated in the forearm by local intra-arterial infusion of methacholine or sodium nitroprusside at baseline and after 2 and 4 h. Forearm blood flow was measured by venous occlusion plethysmography. Lipid oxidation was determined by measuring plasma malondialdehyde levels. Infusion of Intralipid® plus heparin increased the concentration of non-esterified fatty acids to 2.6±1.2 mmol/l and decreased EDV from 27.6±8.7 to 21.0±5.7 mlċmin-1ċ100 ml-1 tissue (P < 0.01). This effect was completely reversed by hyperinsulinaemia (P < 0.01). Hyperinsulinaemia alone increased EDV (to 30.4±9.5 mlċmin-1ċ100 ml-1 tissue; P < 0.01), while endothelium-independent vasodilatation was unaltered by the interventions. Infusion of Intralipid® plus heparin increased malondialdehyde levels from 0.67±0.22 to 1.2±0.37 μmol/l (P < 0.001), while hyperinsulinaemia did not change the malondialdehyde level. In conclusion, an acute increase in serum levels of non-esterified fatty acids increased lipid oxidation and decreased EDV. The effect on EDV of non-esterified fatty acids could be reversed by hyperinsulinaemia.
Thrombopoietin levels in serum and liver tissue in patients with chronic viral hepatitis and hepatocellular carcinoma
Authors: OKUBO Michiko , SHIOTA Goshi , KAWASAKI Hironaka
Published: August 2015

Thrombocytopenia in liver diseases is considered to be due to splenic platelet pooling and accelerated destruction. Since thrombopoietin (TPO), a regulator of thrombopoiesis, is produced mainly in the liver, decreased production of TPO may account for thrombocytopenia in liver diseases. To address this issue, we measured serum TPO, using a sensitive sandwich ELISA, in 108 patients with chronic viral hepatitis, which included chronic hepatitis (CH) and liver cirrhosis (LC), and hepatocellular carcinoma (HCC), and in 29 normal controls. TPO mRNA in 78 liver samples was examined by reverse transcription (RT)-PCR. Platelet counts in CH, LC, HCC and controls were 176±15×109/l, 81±8×109/l, 99±7×109/l and 234±9×109/l respectively. Serum TPO levels in CH, LC and HCC were 2.79±0.4 fmol/ml, 1.49±0.2 fmol/ml and 1.97±0.2 fmol/ml, and were higher than those of controls. Serum TPO levels were positively correlated with prothrombin time and serum albumin (P < 0.05, in each case), and negatively correlated with Indocyanine Green test and Pugh score (P < 0.01 and P < 0.05 respectively). However, RT-PCR and immunohistochemistry showed that expression of TPO mRNA and protein were similar in the different liver diseases, suggesting that serum TPO is a reflection of the total mass of functional liver. Platelet counts were negatively correlated with spleen index, but not with serum TPO. These results suggest that thrombocytopenia in liver disease is not directly associated with serum TPO but is associated with hypersplenism.
Science, art and drug discovery: a personal perspective
Authors: CAMPBELL Simon F.
Published: August 2015

The research programme that started in 1985 led to the approval of Sildenafil (Viagra®), in 1998, as the first oral treatment for male erectile dysfunction. The initial project objective was the design and synthesis of novel inhibitors of phosphodiesterase that would increase tissue levels of cGMP, and that could be beneficial for the treatment of cardiovascular conditions. Starting from zaprinast, a weak phosphodiesterase inhibitor, computer modelling guided rational medicinal chemistry to achieve significant increases in potency and selectivity for the 5-isoenzyme within a novel series of pyrazolopyrimidinones. Optimization of structure–activity relationships and pharmacokinetic properties led to sildenafil, which proved essentially devoid of cardiovascular activity in clinical trials. However, the emerging role of nitric oxide and cGMP in controlling blood flow in the penis suggested that sildenafil would have a beneficial effect on erectile function. This hypothesis was confirmed by extensive clinical trials in nearly 5000 patients and the Food and Drug Administration approved sildenafil in March 1998 for male erectile dysfunction. Sildenafil is now available in over 100 countries and more than 150 million tablets have been dispensed worldwide. The sildenafil research programme reflects a traditional approach to drug discovery, but pressures to improve productivity have prompted major investments in genome sciences and new technologies. The impact of these initiatives on the drug discovery paradigm will be discussed, particularly with respect to shortening time scales between identifying gene sequences and submitting innovative products for regulatory approval.
The hypomagnesaemic action of FK506: urinary excretion of magnesium and calcium and the role of parathyroid hormone
Authors: LOTE Christopher J. , THEWLES Andrew , WOOD Jeanne A. , ZAFAR Tariq
Published: August 2015

A side-effect of the immunosuppressive drug FK506 (Prograf; tacrolimus) is hypomagnesaemia. We have investigated the effects of short-term (7-day) treatment of rats with FK506, using a protocol designed to indicate whether there are modifications in the renal tubular handling of magnesium and other electrolytes, or in the tissue deposition of magnesium, which may account for the hypomagnesaemia. We have also investigated whether parathyroid hormone has a role in the observed hypomagnesaemia. Two studies have been performed; in the first we administered FK506 (0.5 mgċkg-1 body weightċday-1) or vehicle by intraperitoneal injection for 7 days, and then housed the rats in metabolic cages for the 24 h collection of urine. At the end of the metabolic cage period, the animals were anaesthetized, and blood and tissue samples were taken for analysis. In the second set of experiments the dosage regime was identical, but at the end of the treatment period the animals were anaesthetized for implantation of arterial and venous cannulae, and then received a saline (plus inulin) infusion for 6 h, during which time blood and urine samples were collected. The dose of FK506 employed did not decrease the glomerular filtration rate. FK506 elicited hypomagnesaemia in both sets of experiments, accompanied by inappropriately high fractional excretion of magnesium. There was also evidence of disruption of the normal renal reabsorption of calcium, but this did not result in hypocalcaemia. Plasma parathyroid hormone activity was not significantly different between the two groups, and there was no evidence of altered tissue content of magnesium in kidney, liver, heart, skeletal muscle or bone. The study confirms that hypomagnesaemia is a significant side-effect of FK506, even at a relatively low dose which did not decrease the glomerular filtration rate. The effect is not due to a decrease in parathyroid hormone release, or to translocation of magnesium from plasma to tissues, but does reflect decreased renal tubular magnesium (and calcium) reabsorption.
Effects of insulin per se on neuroendocrine and metabolic counter-regulatory responses to hypoglycaemia
Authors: GALASSETTI Pietro , DAVIS Stephen N.
Published: August 2015

We examined and compared findings from studies aimed at detecting and quantifying an effect of insulin per se on counter-regulatory responses to hypoglycaemia. The experimental protocols used in many of these studies were very different with regard to study design and patient population, resulting at times in inconsistencies and discrepancies. Taken together, the results from this extensive body of work clearly indicate that, at similar levels of hypoglycaemia, greater hyperinsulinaemia results in enhanced counter-regulatory responses. This enhancement includes higher circulating levels of counter-regulatory hormones (adrenaline, noradrenaline, cortisol and growth hormone, but not glucagon), more intense activation of hypoglycaemic symptoms (both neural-sympathetic and adrenal-sympathetic), and greater deterioration of neuropsychological skills. The insulin-induced enhancement of counter-regulatory responses is not influenced by gender, is present in several animal species, and applies to healthy subjects as well as to patients with Type I diabetes. The underlying mechanisms remain speculative, and possibly include a direct neuromodulatory effect and/or suppression of glucose utilization in various areas of the brain, which either independently or in a hierarchical fashion trigger the sequence of downstream counter-regulatory events.
Comparison of two indices for forearm noradrenaline release in humans
Authors: RONGEN Gerard A. , LENDERS Jacques W. M. , SMITS Paul , FLORAS John S.
Published: August 2015

Although there is as yet no method which measures directly the neuronal release of noradrenaline in humans in vivo, the isotope dilution technique with [3H]noradrenaline has been applied to estimate forearm neuronal noradrenaline release into plasma. Two different equations have been developed for this purpose: one to estimate the spillover of noradrenaline into the venous effluent, and a modified formula (often referred to as the appearance rate) which may reflect more closely changes in the neuronal release of noradrenaline into the synaptic cleft, particularly during interventions that alter forearm blood flow. The present study was performed to compare the effects of two interventions known to exert contrasting actions on neuronal forearm noradrenaline release and forearm blood flow. Intra-arterial infusion of sodium nitroprusside at doses without systemic effect increases forearm blood flow, but not neuronal noradrenaline release. In contrast, lower-body negative pressure at -25 mmHg causes forearm vasoconstriction by stimulating neuronal noradrenaline release. During sodium nitroprusside infusion, forearm noradrenaline spillover increased from 1.1±0.3 to 2.2±1.0 pmol·min-1·100 ml-1 (P < 0.05), whereas the forearm noradrenaline appearance rate was unchanged. Lower-body negative pressure did not affect the forearm noradrenaline spillover rate, but increased the forearm noradrenaline appearance rate from 3.4±0.4 pmol·min-1·100 ml-1 at baseline to 5.0±0.9 pmol·min-1·100 ml-1 (P < 0.05). These results indicate that the noradrenaline appearance rate provides the better approximation of changes in forearm neuronal noradrenaline release in response to stimuli which alter local blood flow.
Vasodilator prostanoids, but not nitric oxide, may account for skeletal muscle hyperaemia in Type I diabetes mellitus
Authors: SKYRME-JONES R. Andrew P. , O'BRIEN Richard C. , MEREDITH Ian T.
Published: August 2015

We and others have previously documented increased resting and exercise-induced skeletal muscle blood flow in young subjects with Type I (insulin-dependent) diabetes mellitus compared with healthy controls. Both NO and prostanoids are important regulators of vascular tone and may therefore contribute to this hyperaemia. The aim of the present study was to determine the contribution of NO and vasodilator prostanoids to this skeletal muscle hyperaemia in diabetes. We assessed the effects of infusion into the intrabrachial artery of the cyclo-oxygenase inhibitor acetylsalicylic acid (ASA; aspirin) and of the L-arginine analogue NG-monomethyl-L-arginine (L-NMMA) on skeletal muscle blood flow in subjects with Type I diabetes mellitus (DM subjects) and control subjects. Blood flow was measured by venous occlusion plethysmography. Isotonic forearm exercise involved 2 min of wrist flexion and extension. Resting flow (forearm blood flow; FBF) was augmented in DM subjects, as was peak exercise-related blood flow (PFBF) and the volume repaid to the forearm 5 min after exercise (AUC 5, where AUC is area under the flow–time curve) (P < 0.05), even when accounting for differences in basal flow. Infusion of L-NMMA reduced resting flow by 48% in controls (P < 0.005) and by 12% in DM subjects (not significant). L-NMMA reduced PFBF and AUC 5 by 29% (P < 0.05) and 39% (P < 0.0005) respectively in controls, but had no significant effect on these parameters in DM subjects. Infusion of ASA reduced FBF, PFBF and AUC 5 in both DM (P < 0.05) and control (P < 0.05) subjects, but the magnitude of this reduction was greater in DM than in control subjects (ANOVA, P < 0.05), even when differences in resting FBF were accounted for. Indeed, ASA eliminated the differences in FBF, PFBF and AUC 5 between DM and control subjects. Thus increased release of vasodilator prostanoids, rather than of NO, appears to account for skeletal muscle hyperaemia in Type I diabetes.
Effect of ciprofloxacin on the activation of the transcription factors nuclear factor κB, activator protein-1 and nuclear factor-interleukin-6, and interleukin-6 and interleukin-8 mRNA expression in a human endothelial cell line
Authors: GALLEY Helen F. , DHILLON Jatinder K. , PATERSON Ross L. , WEBSTER Nigel R.
Published: August 2015

Quinolone antibiotics such as ciprofloxacin modify immune and inflammatory responses in some cells. We have shown previously that ciprofloxacin decreases the accumulation of interleukin (IL)-6 protein from a human endothelial cell line, whilst IL-8 protein production was increased. It is not known whether this occurs through effects on transcription and mRNA expression. We therefore investigated the effect of ciprofloxacin on mRNA for IL-6 and IL-8, and on three transcription factors known to be involved in the regulation of these cytokines. We investigated the effect of ciprofloxacin on tumour necrosis factor α- and IL-1β-mediated activation of the transcription factors nuclear factor κB (NFκB), activator protein-1 (AP-1) and nuclear factor IL-6 (NF-IL-6) using an electrophoretic mobility shift assay, and the effect on expression of mRNA for IL-6 and IL-8 by reverse transcriptase–PCR in the EAhy926 endothelial cell line. Ciprofloxacin decreased IL-6 mRNA (P < 0.05) and increased IL-8 mRNA (P < 0.05) expression. Ciprofloxacin did not modulate activation of NFκB or AP-1. However, NF-IL-6 binding was decreased in the presence of 100 µg/ml ciprofloxacin (P < 0.05). The study shows that ciprofloxacin-mediated decreased IL-6 release by a human endothelial cell line is reflected by decreased mRNA expression and decreased NF-IL-6 but not NFkB or AP-1 activation. Increased IL-8 mRNA in response to ciprofloxacin was not reflected by altered transcription factor activation and may represent increased mRNA stability.
Mesenteric hyporesponsiveness in cirrhotic rats with ascites: role of cGMP and K+ channels
Authors: ATUCHA Noemí M. , ORTÍZ M. Clara , FORTEPIANI Lourdes A. , NADAL Francisco Javier A. , MARTÍNEZ-PRIETO Concepción , GARCÍA-ESTAÑ Joaquín
Published: August 2015

The mechanisms that mediate hyporesponsiveness to vasoconstrictors in liver cirrhosis are not completely established. In the present study we have explored the role of NO and potassium channels by studying the pressor response to methoxamine in rats with carbon tetrachloride-induced cirrhosis with ascites. Experiments were performed in the isolated and perfused mesenteric arterial bed of control rats and of cirrhotic rats with ascites. Pressor responses to methoxamine, an α-adrenergic agonist, were analysed under basal conditions, after inhibition of guanylate cyclase with Methylene Blue (MB; 10 µM), after inhibition of NO synthesis with NG-nitro-L-arginine (L-NNA; 100 µM) and after blockade of potassium channels with tetraethylammonium (TEA; 3 mM). Compared with those from controls, preparations from cirrhotic rats showed a lower pressor response to methoxamine (maximum: controls, 114.4±6.8 mmHg; cirrhotic rats, 74.7±7.3 mmHg). Pretreatment with MB or L-NNA increased the responses in both groups, but without correcting the lower than normal response of the cirrhotic rats. Pretreatment with TEA alone did not modify the responses as compared with the untreated groups. Pretreatment with TEA plus MB or TEA plus L-NNA also potentiated the responses, and the responses of the cirrhotic animals were greater than those of the groups treated with MB or L-NNA alone. However, no treatment completely normalized the lower response of the mesenteries from cirrhotic animals, suggesting that factors other than NO and potassium channels also participate, although to a lesser degree, in the lower pressor response of the mesenteric arterial bed of animals with cirrhosis. These results confirm that NO and potassium channels are important mediators of the lower vascular pressor response of the mesenteric bed of cirrhotic rats with ascites. This effect seems to be mediated by the NO-dependent formation of cGMP and by the NO-dependent and -independent activation of potassium channels.
Acute effects of oxygen and carbon dioxide on retinal vascular network geometry in hypertensive and normotensive subjects
Authors: CHAPMAN N. , HAIMES G. , STANTON A. V. , THOM S. A. , HUGHES A. D.
Published: August 2015

The optimal design of vascular networks maximizes circulatory efficiency while minimizing power costs. We investigated the effects of acute changes in vascular tone on retinal arteriolar network geometry. Six hypertensive and six normotensive subjects each breathed air, 5% CO2 (with 12% O2), and 100% O2 for 5 min periods in random order. Retinal photographs were taken at the end of each test period. Bifurcation angles and arteriolar diameters were measured using operator-directed image analysis, and junction exponents were calculated. Arteriolar diameters narrowed on breathing O2. The magnitude of this change was significantly greater in normotensive than in hypertensive subjects. Angles narrowed in normotensive subjects, but not significantly in hypertensive subjects. Arteriolar diameters increased significantly on breathing CO2 in normotensive but not in hypertensive subjects, but there were no changes in angles. Despite changes in diameter, junction exponents did not change under any conditions. Vascular reactivity in the retinal arteriolar bed appears to be diminished in hypertensive subjects. The failure of junction exponents to change, despite alterations in diameter, suggests that arteriolar diameters at retinal bifurcations adhere to optimality principles when exposed to acute vasoactive stress. As vasoconstriction is associated with the narrowing of bifurcation angles, previous observations showing narrowed angles in hypertensive subjects could be explained by increased tone in the retinal arteriolar bed.
Mitogenic action of lysophosphatidic acid in proximal tubular epithelial cells obtained from voided human urine
Authors: KUMAGAI Naonori , INOUE Chiyoko N. , KONDO Yoshiaki , IINUMA Kazuie
Published: August 2015

Focal tubular cell multiplication at sites on an injured nephron is a critical event in the recovery phase following acute tubular necrosis. During this process, numerous viable tubular cells exfoliate and are shed into the urine. Lysophosphatidic acid (LPA) is generated in the plasma membrane of injured cells and acts as an intercellular mediator of various biological processes, including inflammation, proliferation and repair. In the present study, exfoliated proximal tubule (PT) cells were isolated from human urine and the mitogenic effects of LPA were investigated as a model of repair and proliferation following renal injury. LPA stimulated a 23.5% increase in DNA synthesis, a 29.4% increase in cell number and an 86.6% decrease in cAMP content. All of these responses were pertussis toxin sensitive, indicating the involvement of Gi-type G-proteins in LPA signalling. Conversely, the LPA-induced DNA synthesis and the decrease in intracellular cAMP content were insensitive to wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K), suggesting a mitogenic response via PI3K-independent mechanisms. Furthermore, we detected specific mRNA transcripts for the recently cloned human LPA-receptors, endothelial differentiation gene (Edg)-2 and Edg-4 (Edg-2 ≫ Edg-4) by reverse transcription-PCR in PT cells. Our data suggest that LPA may behave as a local growth factor in PT cells following tubular injury.
A compound heterozygote for a novel missense mutation (G105R) in exon 3 and a missense mutation (D204E) in exon 5 of the lipoprotein lipase gene in a Japanese infant with hyperchylomicronaemia
Authors: IKEDA Yasuyuki , GOJI Katsumi , TAKAGI Atsuko
Published: August 2015

We systematically investigated the molecular defects resulting in primary lipoprotein lipase (LPL) deficiency in a Japanese male infant (hereafter called ‘the patient’) with severe fasting hypertriglyceridaemia (type I hyperlipoproteinaemia). The primary LPL deficiency was diagnosed on the basis of the findings that no LPL activity was detected in post-heparin plasma (PHP) and that the immunoreactive LPL mass in PHP was less than 2% of the control level. The patient was a compound heterozygote for a novel missense mutation (G̲568GA → A̲GA/Gly105 → Arg; G105R) in exon 3 and a missense mutation (GAC̲867→GAG̲/Asp204→Glu; D204E) in exon 5 of the LPL gene. The biological significance of both missense mutations was examined by an in vitro study of the expression of the mutant G105R LPL cDNA and D204E LPL cDNA in COS-1 cells. Both mutant LPLs were catalytically inactive and were barely released by heparin from the expressing COS-1 cells. These findings explain the failure to detect LPL activity and immunoreactive LPL mass in the patient's PHP. The G105R allele could be detected by digestion with the BsmAI restriction enzyme, and the D204E allele by digestion with HincII. The patient inherited the G105R allele from his mother and the D204E allele from his father. His parents were heterozygotes for the corresponding mutant allele, but normolipidaemic. The novel G105R missense mutation could not be detected by conventional analysis of single-strand conformation polymorphism, but it was identified by extensive sequencing of the entire exons and their flanking regions in the LPL gene.
Hydrocortisone abolishes the angiotensin II-mediated potentiation of endothelin-I in bovine bronchi
Authors: BROWN A. J. , NALLY J. E.
Published: August 2015

Angiotensin II potentiates methacholine-evoked bronchoconstriction both in bovine airways in vitro and in asthmatic patients in vivo. Angiotensin II also potentiates endothelin-1-evoked contractions in vitro, but fails to alter such contractions in vivo. One possible confounding factor in patients is their use of inhaled corticosteroids. Accordingly the present study examined the effects of hydrocortisone (cortisol) on contractions evoked by methacholine and endothelin-1 in the presence and absence of angiotensin II. Contractions of rings of isolated bovine airways were measured isometrically in organ baths. Concentration–response curves were obtained for endothelin-1 or methacholine in the presence and absence of angiotensin II, hydrocortisone and a combination of angiotensin II and hydrocortisone. Hydrocortisone abolished the angiotensin II-mediated potentiation of endothelin-1-evoked, but not methacholine-evoked, contractions. Hydrocortisone alone evoked the enhancement of methacholine responses, similar to the effect produced by angiotensin II. While species differences may exist, our present results suggest that the use of corticosteroids can have a profound effect on the interaction between angiotensin II and endothelin-1. Accordingly, the presence of inhaled corticosteroids might explain the differences between the results obtained in vitro and in vivo.
Low-frequency heart rate variability: reproducibility in cardiac transplant recipients and normal subjects
Authors: LORD S. W. , SENIOR R. R. , DAS M. , WHITTAM A. M. , MURRAY A. , MCCOMB J. M.
Published: August 2015

Heart rate variability is a measure of autonomic nervous influence on the heart. It has been suggested that it could be used to detect autonomic reinnervation to the transplanted heart, but the reproducibility of the measurement is unknown. In the present study, 21 cardiac transplant recipients and 21 normal subjects were recruited. Three measurements of heart rate variability were performed during the day: in the morning, in the early afternoon and in the late afternoon. These tests were then repeated 1 week later and then again 1 week after that, making nine tests in all. The within-subject S.D. was 0.49 log units in normal subjects and 0.79 log units in transplant recipients. In both cases, this is about 15% of the population range. There was significant variation in heart rate variability between different times of day in both groups, and from day to day in transplant recipients. It was concluded that the reproducibility of measurements of heart rate variability is low, and that differences between measurements performed at different times of day should be interpreted with caution.
Homocysteine and thiol metabolites in vitamin B12 deficiency
Authors: RANGANATH L. R. , BAINES M. , ROBERTS N. B.
Published: August 2015

Homocysteine metabolism is increasingly implicated in a diverse group of clinical disorders, including atheromatous vascular disease. We studied the disposition of homocysteine via the trans-sulphuration pathway, plasma glutathione peroxidase (GPx) activity and plasma levels of the sulphated hormone dehydro-epiandrosterone sulphate (DHEAS) in six vitamin B12-deficient human subjects before and after 2 weeks of vitamin B12 repletion, both in the fasting state and following an oral methionine load (0.1 g/kg body weight). Fasting plasma total homocysteine concentrations fell (P = 0.03) and total cysteine concentrations rose significantly (P = 0.048) after treatment for 2 weeks with vitamin B12 injections. The magnitude of the mean fall in the fasting concentration of homocysteine (38.8 µmol/l) was similar to the mean rise in cysteine levels (36.0 µmol/l) following vitamin B12 therapy. Circulating levels of homocysteine were increased at 4 h after a methionine load when compared with fasting levels, both before and after vitamin B12 repletion (P = 0.003 for both). Total cysteinyl-glycine was lower post-methionine than in the fasting state following vitamin B12 therapy (P = 0.007). Fasting plasma GPx fell significantly after 2 weeks of vitamin B12 therapy (P = 0.05). The change in plasma GPx between the fasting state and 4 h after methionine loading was significantly different pre- and post-vitamin B12 therapy (P = 0.05). The present study provides indirect support to the hypothesis that defects in the trans-sulphuration and remethylation of homocysteine produce hyperhomocysteinaemia in vitamin B12 deficiency in human subjects. Elevated homocysteine levels directly or indirectly may up-regulate GPx. Sulphation status, as measured by plasma DHEAS, was unchanged.
Common genetic variants that relate to disorders of lipid transport in Spanish subjects with premature coronary artery disease
Authors: MASANA Ll. , FEBRER G. , CAVANNA J. , BARONI M. G. , MARZ W. , HOFFMANN M. M. , SHINE B. , GALTON D. J.
Published: August 2015

Fifteen common polymorphic variants at six loci (apolipoproteins AI, B, CIII and E, hepatic lipase and lipoprotein lipase) involved in plasma lipid transport have been studied in 210 northern Spanish men, of whom 98 had proven coronary artery disease. The other 112 men were clinically free from coronary artery disease and acted as controls. The genotypes were investigated for relationships with plasma lipid and lipoprotein levels, as well as for the presence of coronary artery disease. As expected, the mean levels of plasma triacylglycerols (triglycerides) and lipoprotein (a) and the number of smokers were significantly higher in the disease group, and high-density lipoprotein (HDL)-cholesterol was significantly lower. Surprisingly, plasma cholesterol and low-density lipoprotein cholesterol were not different between the two groups. With regard to the common mutations, plasma triacylglycerol levels were related to the HindIII variants of lipoprotein lipase (P < 0.05), to the apolipoprotein CIII variant (C3175G in exon 4) and to the apolipoprotein AI XmnI polymorphisms (P < 0.05 and P < 0.02 respectively). The apolipoprotein E variants were related to plasma cholesterol (P < 0.05), HDL-cholesterol (P < 0.02), plasma triacylglycerols (P < 0.05) and the triacylglycerol/HDL ratio (P < 0.01). Only the three-codon insertion/deletion variants of the apolipoprotein B signal peptide region discriminated between the two groups with or without arterial disease (P = 0.02). The possible functional effects of these common mutations are discussed.
Cardiovascular regulation during head-up tilt in healthy 20–30-year-old and 70–75-year-old men
Authors: GABBETT Tim J. , WESTON Shane B. , BARRETT Rod S. , GASS Greg C.
Published: August 2015

This study compared the heart rate, finger arterial pressure (AP) and electromyographic (EMG) activity of selected anti-gravity muscles during the initial and prolonged phases of orthostatic stress in healthy young and older men. Beat-by-beat recordings of heart rate, finger systolic pressure, diastolic pressure and mean AP were made during supine rest and 5 min of 90 ° head-up tilt (HUT) in 18 young (23±1 years) and 15 older (73±1 years) men. The EMG activity of the soleus, tibialis anterior and vastus medialis muscles was recorded. During the first 30 s following 90 ° HUT (immediate response), the young men exhibited significant (P < 0.05) decreases in finger systolic pressure, diastolic pressure and mean AP, followed by a sustained increase in finger AP during the 5 min following 90 ° HUT (prolonged response). The immediate and prolonged finger AP and diastolic pressure responses were not significantly different (P > 0.05) from the values at supine rest for the older men. The mean root mean square EMG activity of the soleus, tibialis anterior and vastus medialis muscles during 90 ° HUT was not significantly different (P > 0.05) from that at supine rest for either group. These results demonstrate that, when compared with healthy older men, young men show larger reductions in finger AP during the initial phase of orthostatic stress. However, during the prolonged phase of orthostatic stress, older men maintain resting finger AP, whereas young men demonstrate a reflex overshoot in finger AP. Finally, differences in lower-limb anti-gravity muscle activation do not account for the contrasting finger AP responses of healthy young and older men.
Effects of oral combined hormone replacement therapy on platelet aggregation in postmenopausal women
Authors: TEEDE Helena J. , MCGRATH Barry P. , TURNER Alan , MAJEWSKI Harry
Published: August 2015

The effects of combined oestrogen/progestin hormone replacement therapy (HRT) on platelet aggregation were studied using women on HRT or placebo. The study involved 32 postmenopausal women (aged 50–75 years) who were enrolled in a double-blind randomized controlled trial, and who received either oral continuous combined HRT (Kliogest®; 2 mg of oestradiol+1 mg of norethisterone) or placebo for a minimum of 6 months. Platelet aggregation was measured by whole-blood impedance aggregometry in response to the agonists collagen, arachidonic acid and ADP. To determine whether the effects of oestrogen on platelets were influenced by platelet-derived nitric oxide, exposure to collagen was repeated in the presence of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA). Mean platelet volume was similar in the two groups. Compared with the placebo group, the women on HRT had similar rates and maximum values of platelet aggregation in response to collagen, arachidonic acid and ADP. Addition of L-NMMA did not alter the aggregation response to collagen in either the HRT or the placebo group. In conclusion, postmenopausal women on oral combined continuous HRT comprising oestradiol and norethisterone had similar whole-blood platelet aggregation rates and maximum platelet aggregation responses to higher doses of platelet agonists when compared with those on placebo. The endogenous platelet nitric oxide system did not appear to affect aggregation in either group.
A simple, highly sensitive and improved method for the measurement of bleomycin-detectable iron: the ‘catalytic iron index’ and its value in the assessment of iron status in haemochromatosis
Authors: BURKITT Mark J. , MILNE Lesley , RAAFAT Alaeddin
Published: August 2015

In the presence of ferrous ions (Fe2+), the anti-tumour agent bleomycin will induce DNA degradation. Degradation of DNA into substances detectable by the thiobarbituric acid test has been used previously for the detection of iron in a form that is capable of catalysing the formation of the potentially harmful hydroxyl free radical. In the present paper, we describe the application of the ethidium-binding assay of DNA damage to the measurement of bleomycin-detectable iron, comparing its performance with the conventional method in the assessment of iron standard solutions and plasma samples from haemochromatosis patients. The ethidium-binding assay proved to be more responsive than the thiobarbituric acid test in the detection of DNA damage induced by very low concentrations of iron, but became saturated at higher iron concentrations. Agreement between the two versions of the assay in the identification of plasma samples containing bleomycin-detectable iron was good, but agreement on the actual concentrations of such iron in the positive samples was poor. This discrepancy is believed to be due to interference with the thiobarbituric acid assay by plasma. Consequently, it was not possible to obtain reliable estimates of free iron concentrations in plasma when using the conventional version of the bleomycin assay. We have devised a parameter of iron status called the catalytic iron index. For healthy, non-haemochromatotic individuals, the mean value of this parameter was found to be 0.81 (range 0.78–0.84; n = 20). Elevated values were observed in some plasma samples from haemochromatosis patients, but these showed no correlation with serum ferritin levels. In contrast, correlations were seen with both serum iron and transferrin saturation levels, but only when these were above the normal range.