bluuebunny/crossref_metadata_2025 huggingface dataset:
Vascular Endothelial Growth Factor (VEGF) is Released from Platelets during Blood Clotting: Implications for Measurement of Circulating VEGF Levels in Clinical Disease
Authors: Webb Nicholas J. A. , Bottomley Martyn J. , Watson Carolyn J. , Brenchley Paul E. C.
Published: August 2015

1. Dysregulated vascular endothelial growth factor (VEGF) expression has been reported in several pathological states based upon evidence of elevated serum VEGF levels. Using two immunoassays for VEGF, this study determines normal plasma and serum VEGF ranges, determines which are more likely to reflect circulating VEGF levels and investigates a potential contribution of VEGF from platelets to VEGF levels detected in serum.

2. The presence of soluble VEGF receptor, sflt-1, at a molar excess of 7:1 significantly reduced measured VEGF levels in both assays. Serum VEGF levels were higher than plasma levels in children [(mean ± S.E.M.) 306.1 ± 39.4 versus 107.4 ± 24.9 pg/ml, P < 0.0001] and adults (249.4 ± 46.4 versus 76.1 ± 10.7 pg/ml, P < 0.0001). Serum VEGF increased with clotting time (P = 0.0005 t0 compared with 2 h samples); plasma VEGF levels were not affected by time between sampling and centrifugation.

3. Calcium-induced clotting of platelet-rich but not platelet-poor plasma induced VEGF release with a proportional response between platelet count and VEGF level and isolated platelets released significant quantities of VEGF upon incubation with thrombin. Reverse transcriptase—PCR studies confirmed that platelets express VEGF121 and VEGF165 mRNA.

4. These data suggest that plasma is the preferred medium to measure VEGF levels; a significant and highly variable platelet-mediated secretion of VEGF during the clotting process invalidates the use of serum as an indicator of circulating VEGF levels in disease states.
Plasma Leptin in Chronic Inflammatory Bowel Disease and HIV: Implications for the Pathogenesis of Anorexia and Weight Loss
Authors: Ballinger Anne , Kelly Paul , Hallyburton Elizabeth , Besser Rachel , Farthing Michael
Published: August 2015

1. Leptin inhibits food intake and is an important regulator of long-term energy balance. In rodents, plasma concentrations of leptin are increased by administration of interleukin-1 and tumour necrosis factor. Hyperleptinaemia may mediate the anorexia and weight loss which is observed in chronic infections and inflammatory conditions.

2. Plasma leptin and soluble tumour necrosis factor receptor (sTNF-r55) concentrations were measured in patients with inflammatory bowel disease and acquired immunodeficiency syndrome (AIDS), and healthy controls.

3. The patients with AIDS were severely wasted [% body fat 12 (9–16); median (interquartile range)] compared with those with inflammatory bowel disease (25.1 (19–31.5)] and control subjects [29.4 (23.6–37.8)]. Leptin concentrations were highly correlated with percentage body fat in controls (r = 0.74, P < 0.001) and patients with IBD (r = 0.73, P < 0.001) but not in the patients with AIDS (r = −0.024). Leptin concentrations were similar in the inflammatory bowel disease (4.8 (2.6–10.1) ng/ml] and control groups [8.0 (3.1–14.1) ng/ml] but were significantly lower (P < 0.05) in patients with AIDS (1.8 (1.5–2.3) ng/ml] after 23 patients were matched for sex and percentage body fat in patients with inflammatory bowel disease (2.4 (1.8–4.1) ng/ml]. Plasma concentrations of sTNF-r55 were higher in both the patients with inflammatory bowel disease [0.19 (0.16–0.23) ng/ml] and those with AIDS [4.8 (2.8–7.3) ng/ml] compared with controls [0.14 (0.09–0.16) ng/ml] but were not correlated with either percentage body fat or plasma leptin concentrations.

4. Hyperleptinaemia does not appear to mediate the anorexia and weight loss associated with inflammatory bowel disease and AIDS. In patients with AIDS with extreme wasting there was no relationship between body fat and leptin and this may be related to the rapid weight loss which occurs in these patients.
Abnormal Transoesophageal Doppler Coronary Flow Reserve in Patients with Dilated Cardiomyopathy: Relationship to Exercise Capacity
Authors: Chati Z. , Bruntz J. F. , Ethévenot G. , Aliot E. , Zannad F.
Published: August 2015

1. In patients with dilated cardiomyopathy, abnormal myocardial blood flow may contribute to poor myocardial function.

2. The aim of this study was to investigate the possible contribution of abnormal myocardial blood flow to the limitation of exercise capacity in patients with dilated cardiomyopathy.

3. Coronary flow reserve was assessed in 16 patients with dilated cardiomyopathy and 9 matched normal control individuals. All participants had angiographically normal coronary arteries. At rest and after dipyridamole infusion (0.56 mg/kg intravenously), peak systolic and diastolic coronary flow velocities were measured in the proximal left anterior descending coronary artery using transoesophageal pulsed Doppler echocardiography, guided by colour flow imaging. Coronary flow reserve was calculated as the ratio of hyperaemic to basal diastolic and systolic peak coronary flow reserve.

4. Baseline diastolic and systolic coronary flow velocities were significantly higher in patients (50 ± 6 and 30 ± 4 cm/s respectively) compared with control individuals (37 ± 3 and 20 ± 1 cm/s respectively) (mean ± S.E.M.) (P < 0.05). Diastolic and systolic peak coronary flow reserve were significantly lower in patients (1.60 ± 0.14 and 1.40 ± 0.09 respectively) compared with control individuals (2.89 ± 0.15 and 2.17 ± 0.17 respectively) (P < 0.001). Although peak Vo2 and exercise time were significantly lower in patients compared with control individuals, coronary flow reserve did not correlate to exercise capacity in patients with dilated cardiomyopathy.

5. These results confirm the abnormalities of coronary flow reserve previously observed in patients with dilated cardiomyopathy, but suggest that such abnormalities do not contribute to the limitation of exercise capacity in these patients.
Regulation of Mitochondrial ATP Synthase Activity in Human Myocardium
Authors: Das Anibh M.
Published: August 2015

1. In previous studies regulation of the F1F0-ATPase of mitochondrial complex V (ATP synthase) has been demonstrated in rat cardiomyocytes, canine mycocardium and skeletal muscle from children. The aim of the present study was to examine regulation of ATP synthase in human myocardium in response to different metabolic states.

2. Biopsy material was obtained from 10 children undergoing cardiac surgery. Mitochondria in the post-nuclear supernatant were incubated under different metabolic conditions for 15 min and then broken by sonication. ATP synthase was measured spectrophotometrically using a coupled enzyme assay.

3. ATP synthase can be rapidly measured in sonicated preparations of heart mitochondria from children. We show that direct regulation at the level of ATP synthase occurs in these mitochondria. ATP synthase capacity is decreased in response to blocking of the respiratory chain by cyanide (mimicking anoxia) or uncoupling of mitochondria, falling to 76% and 66% of control values respectively. Upregulation of ATP synthase can be demonstrated in heart mitochondria when the calcium concentration in the incubation medium is increased to 5 μM (130% of control).

4. ATP synthase is actively regulated in heart mitochondria from children. The enzyme is upregulated in response to increased calcium. This transition may reflect the increased energy demand when cardiac workload is increased.
Renoprotective Differences between Perindopril and Enalapril in the Diabetic Hypertensive Rat Do Not Reflect Glomerular Angiotensin-Converting Enzyme Activity
Authors: Duggan K. A. , Hodge G. , Makarious M. M. , Charlesworth J. A.
Published: August 2015

1. The various angiotensin-converting enzyme inhibitors have structural differences which affect their affinities for the catalytic sites on converting enzyme. We postulated that such differences might result in differences in renoprotective efficacy. We investigated this in the diabetic spontaneous hypertensive rat. We also investigated whether these differences might reflect variations in glomerular or plasma angiotensin-converting enzyme activity.

2. One week after induction of diabetes, rats were started on antihypertensive therapy: enalapril, 10 mg · day−1 · kg−1, or perindopril, 4 mg · day−1 · kg−1, in the drinking water. After 3 months, the rats were killed, blood samples were taken and tissues were harvested. Angiotensin-converting enzyme activity in isolated glomeruli and plasma was measured by fluorimetric assay. Glomerular protein content was also determined.

3. Urinary protein excretion was significantly lower in perindopril-treated rats than in either controls (P < 0.0005) or enalapril-treated rats P < 0.05). Glomerular protein content was also lower in perindopril-treated rats (P < 0.05 versus enalapril; P < 0.005 versus control). There was no difference in glomerular angiotensin-converting enzyme activity between the two inhibitors although both were lower than control values (enalapril P < 0.025; perindopril P < 0.025). Plasma angiotensin-converting enzyme activity was significantly lower in the perindopril group than in either control (P < 0.005) or the enalapril group (P < 0.01).

4. We conclude that in the spontaneous hypertensive rat with streptozotocin-induced diabetes, perindopril is more effective than enalapril in reducing proteinuria and glomerular protein accumulation. This difference does not result from differences in glomerular-converting enzyme activity.
Effects of Skin Cooling on Airway Reactivity in Asthma
Authors: Skowronski M. E. , Ciufo R. , Nelson J. A. , McFadden E. R.
Published: August 2015

1. Environmental contact with cold air is a common cause of respiratory distress in obstructive lung disease, and direct and reflex changes in bronchial calibre are well documented with this stimulus when it is inhaled or contacts the exposed skin respectively. It is now known that skin chilling does not amplify the effects of breathing cold air, but it is not established if this lack of interaction is unique, or applies to other forms of airway constrictors.

2. To provide data on this issue, 10 subjects with atopic asthma underwent methacholine bronchoprovocations with and without chilling of the integument of their heads and thoraces for 30 min. Chilling was accomplished with a specially designed thermal garment. Spirometry as well as core and skin temperatures were serially monitored during all experiments.

3. In the control phase (no cooling), integumental temperatures rose slightly, the forced expiratory volume in 1.0 s (FEV1.0) did not change, and the mean provocative concentration of methacholine required to reduce the FEV1.0 by 20% (PC20 meth) was 0.47 ± 0.17 mg/ml (2.4 ± 0.87 mmol/l). In the cold trial, the temperature of the back fell 5.1 ± 1.7 °C to 28.7 ± 1.8 °C (P < 0.01), core temperatures did not change, and airway obstruction developed (ΔFEV1.0 = −6.7 ± 2.1%; P < 0.05). The PC20 meth, however, was unaltered [PC20 meth = 0.45 ± 0.13 mg/ml (2.3 ± 0.66 mmol/1); P = 0.85].

4. These results demonstrate that although skin cooling produces mild airway obstruction in subjects with asthma, it does not change the response to non-specific bronchoconstrictors such as methacholine.
Cardiovascular Autonomic Testing in Adolescents with Type I (Insulin-Dependent) Diabetes Mellitus: An 18-Month Follow-up Study
Authors: Scaramuzza Andrea , Salvucci Fabrizio , Leuzzi Stefano , Radaelli Alberto , d'Annunzio Giuseppe , Fratino Pietro , Lorini Renata , Bernardi Luciano
Published: August 2015

1. Autonomic abnormalities are frequent in adult patients with diabetes mellitus and progress slowly; little is known about frequency and progression of autonomic abnormalities in childhood.

2. To assess whether autonomic abnormalities are already present in childhood, we evaluated the cardiovascular reflexes, the spectral analysis of spontaneous fluctuations in RR interval and blood pressure (low- and high-frequency), and the baroreflex sensitivity at rest, and after vagal (controlled breathing) and sympathetic activation (tilting) in 25 adolescents with Type I diabetes mellitus, aged 10–17 years, at baseline and after 18 months follow-up, and in 20 age- and sex-matched controls.

3. Cardiovascular reflexes were similar in both patients and controls. Similar significant changes in percentage low- and high-frequency (P < 0.005) from rest to tilting and to control breathing were observed in both patients and controls. The baroreflex sensitivity was also similar in patients and controls. Mild and non-systematic correlations were observed between autonomic tests and disease duration or metabolic control. After 18 months follow-up no changes were observed in any of the measured variables. Correlations with metabolic control remained unchanged.

4. These results indicate a substantial stability of cardiovascular autonomic function in childhood diabetes, and suggest that autonomic abnormalities are likely to develop at an older age.
Effects of morphine administration on the fetal production of oxytocin in labour
Authors: LINDOW S. W. , HENDRICKS M. S. , THOMPSON J. W. , VAN DER SPUY Z. M.
Published: August 2015

1.Animal and human work has indicated that maternal oxytocin secretion is under the control of endogenous opiates. Previous workers have described the fetal production of oxytocin in addition to maternal production. The study of the interaction between exogenously administered opiates and oxytocin secretion may give insight into the activity of any opiate-mediated regulatory mechanism of oxytocin secretion in the fetus. This study was designed to investigate the effect of an opiate (5 mg of morphine) given to the mother on the fetal production of oxytocin in labour.

2.Morphine was given by the attending clinicians for analgesic purposes to women in the first stage of labour. After delivery umbilical artery vein and maternal vein specimens were taken.

3.Four groups of patients were studied: women after normal vaginal delivery without analgesia in labour (n = 10); women after normal vaginal delivery who had morphine administration in the first stage of labour (n = 12); women who had an emergency Caesarean section in the first stage of labour (n = 11); women who had an elective Caesarean section at term who were not in labour (n = 11).

4.Oxytocin levels were measured by radioimmunoassay in the maternal vein, umbilical artery and umbilical vein specimens. Morphine was measured by radioimmunoassay in the umbilical vein specimens.

5.The umbilical artery minus vein concentration of oxytocin was calculated for each patient (A-V). There was no change in the umbilical (A-V) concentration of oxytocin if morphine had been given to the mother in labour; this applied to fetuses delivered vaginally or by Caesarean section. When the fetuses who were exposed to morphine were analysed separately, there was no correlation between the umbilical vein morphine concentration and the umbilical (A-V) oxytocin concentration either in Caesarean or vaginal deliveries.

6.Fetal oxytocin production was not affected by the maternal administration of morphine in the first stage of labour. This applies to the oxytocin production in the first and second stage of labour.
Effect of endothelin-1 on endothelium-derived vascular responsiveness in man
Authors: KRUM Henry , CRANSWICK Noel , PELLIZZER Anne-Marie
Published: August 2015

1.Endothelium-dependent vasodilatation via nitric oxide in response to muscarinic stimulation is decreased in chronic heart failure while basal release of nitric oxide may be increased. As production of the endothelium-derived vasoconstrictor endothelin-1 is increased in chronic heart failure, endothelin-1 may act in an autocrine manner to modulate these effects.

2.To test this, we determined whether prolonged endothelin infusion in normal subjects would reproduce the alterations in basal and stimulated nitric oxide release observed in patients with chronic heart failure. Basal nitric oxide production was determined by measurement of forearm blood flow using strain gauge venous occlusion plethysmography before and after brachial artery infusion of a nitric oxide synthase inhibitor (NG-monomethyl-l-arginine). Stimulated nitric oxide production was determined by brachial artery infusion of acetylcholine. As metabolic vasodilatation is thought to be mediated in part via nitric oxide and is decreased in chronic heart failure, forearm blood flow during peak reactive hyperaemia was also measured. Studies were then repeated during brachial artery infusion of endothelin-1 and a non-specific vasoconstrictor, noradrenaline.

3.Neither basal nor stimulated nitric oxide production was altered by endothelin-1 and noradrenaline infusion. However, absolute forearm blood flow responses to peak reactive hyperaemia were decreased during infusion of endothelin-1 in comparison to noradrenaline. These data suggest that increased endothelin-1 may not contribute greatly to altered basal and stimulated nitric oxide production in patients with chronic heart failure but may contribute to impaired metabolic vasodilatation, by mechanisms presumably unrelated to altered nitric oxide production.
Effect of salt-loading on blood pressure, insulin sensitivity and limb blood flow in normal subjects
Authors: FOO M. , DENVER A. E. , COPPACK S. W. , YUDKIN J. S.
Published: August 2015

1.The aim of this study was to determine the effects of high (220 ;mmol/day) and low (40 ;mmol/day) salt intake for 6 days on blood pressure, leg blood flow and insulin sensitivity in 18 ;healthy normotensive subjects.

2.Twenty-four-hour ambulatory blood pressure was measured at baseline, during salt-loading and salt-depletion. Insulin sensitivity was determined by a two-step euglycaemic–hyperinsulinaemic clamp (low and high insulin infusion rates: 40 and 600 ;m-unit·min-1·m-2 respectively) and leg blood flow by plethysmography.

3.Salt-loading resulted in changes in weight [change between salt-loading and salt-restriction: δ =+0.45 (S.D.±0.69) ;kg, P = 0.015], plasma renin [δ =-11.5 (S.D.±12.9) ;μ-units/l, P = 0.001] and urinary noradrenaline [δ =-8.6 (S.D.±18.7) ;nmol/mmol creatinine, P = 0.05]. There were borderline significant increases in 24-h systolic blood pressure [δ =+5.8 (S.D.±14.2) mmHg, P = 0.06] and plasma volume [δ =+0.29 (S.D.±0.67) litres, P = 0.08].

4.Insulin sensitivity was similar in both salt states. Geometric mean metabolic clearance rate of low-dose insulin: low salt, 5.13 (S.D.×/÷1.35) dl/min; high salt, 4.94 (S.D.×/÷1.37) dl/min, P = 1.0. Geometric mean metabolic clearance rate of high-dose insulin: low salt, 9.68 ;dl/min (S.D.×/÷1.30); high salt, 9.68 (S.D.×/÷1.27) dl/min, P = 0.69.

5.Leg blood flow response to high-dose insulin on high salt increased significantly compared with low salt. Percentage change of blood flow on low salt, δ =+36.6 (S.D.±22.9)% versus high salt, δ =+66.8 (S.D.±52.2)%, P = 0.03.

6.There were no significant relationships between salt-related changes in limb blood flow and changes in insulin sensitivity at either insulin infusion rate.

7.We conclude that salt-loading, despite changing body weight, the renin–angiotensin–aldosterone system, urinary noradrenaline and the leg blood flow response to insulin, has no significant effect on insulin sensitivity. Salt-loading causes dissociated effects on insulin-induced vasodilatation and glucose disposal.
Inter-α-inhibitor in calcium stones
Authors: DAWSON Caroline J. , GROVER Phulwinder K. , KANELLOS Jerry , PHAM Hung , KUPCZYK Gosia , OATES Adrian , RYALL Rosemary L.
Published: August 2015

1.A broad spectrum of proteins has been detected within calcium stones. A newcomer to the field of urolithiasis is the blood protein inter-α-inhibitor. Inter-α-inhibitor comprises three protein chains linked by chondroitin sulphate: two heavy chains, H1 (65 ;kDa) and H2 (70 ;kDa) and a light chain (approx. 30 ;kDa) most commonly known as bikunin. The physiological function of the two heavy chains is unknown; nor has their presence been reported in urine. However, bikunin has been implicated in various renal diseases, including urolithiasis.

2.This study was undertaken to determine which chains of inter-α-inhibitor are actually present in calcium kidney stones. Organic extracts were obtained from 10 calcium stones and analysed by SDS/PAGE and Western blotting. The H1 and H2 chains of inter-α-inhibitor were detected in 9 of the 10 stones, but only one stone contained a protein with a molecular mass close to that of bikunin (30–35 ;kDa).

3.These results demonstrate for the first time that H1 and H2 are present in stones and show that the bikunin chain of inter-α-inhibitor may not be the only part of the molecule implicated in stone formation.
Lack of habituation of the pattern of cardiovascular response evoked by sound in subjects with primary Raynaud's disease
Authors: EDWARDS Clare M. , MARSHALL Janice M. , PUGH M.
Published: August 2015

1.The vasospasm of primary Raynaud's disease can be triggered by acute emotional stress. We have studied the pattern of cardiovascular response evoked by acute emotional stress, a sound stimulus of 90 ;dB, 2 ;kHz for 30 ;s, in eight subjects with primary Raynaud's disease and in eight age- and sex-matched controls, the sound being repeated five times on each of days 1, 3 and 5.

2.In controls, the first sound evoked the pattern of the alerting response that is characteristic of acute emotional stress: a rise in arterial pressure and heart rate, a decrease in vascular conductance in the cutaneous circulation of the digit, assessed by laser Doppler recording of erythrocyte (red cell) flux in the digit divided by arterial pressure, and an increase in forearm muscle vascular conductance, assessed from forearm blood flow recorded by venous occlusion plethysmography divided by arterial pressure.

3.In the subjects with primary Raynaud's disease, baselines of arterial pressure, digital cutaneous vascular conductance and forearm vascular conductance were not significantly different from those of the controls and they too showed the alerting response to the first sound, the magnitudes of the changes being comparable to those of the controls.

4.In both the controls and subjects with primary Raynaud's disease, the evoked responses were consistent on repetition of the sound on day 1. In contrast, judging from the means of the changes evoked on each day, the controls showed habituation of the individual components of the alerting response over days 1, 3 and 5, whereas the subjects with primary Raynaud's disease showed no habituation of either the forearm muscle vasodilatation or the digital vasoconstriction. Conversely, the decrease in digital cutaneous vascular conductance evoked by a single deep breath was fully reproducible in both controls and subjects with primary Raynaud's disease when tested at the beginning and end of each experimental day.

5.These results allow the novel conclusion that subjects with primary Raynaud's disease have an abnormality of the central neural modulation of the brain stem areas that integrate the cardiovascular components of the alerting response to acute emotional stress, such that habituation of the vasodilator and vasoconstrictor components of the response on repetition of the stimulus is impaired. We propose that such persistence of vasoconstrictor responses to stressful stimuli predisposes to vasospasm, particularly if neurally mediated vasoconstriction is reinforced by locally released vasoconstrictor factors.
Beneficial effect of vitamin E administration on nitric oxide function in subjects with hypercholesterolaemia
Authors: GREEN Daniel , O'DRISCOLL Gerry , RANKIN James M. , MAIORANA Andrew J. , TAYLOR Roger R.
Published: August 2015

1.Vitamin E administration improves endothelial function in hypercholesterolaemic animals but, generally, has not been found to do so in man. The aim of this study was to determine whether vitamin E administration improves basal or stimulated function of the nitric oxide (·NO) dilator system in patients with hypercholesterolaemia.

2.Seven subjects aged 47±3 (±S.E.M.) years with moderately elevated serum cholesterol concentrations (6.0±0.1 ;mmol/l) were given 4 weeks of placebo therapy followed by 500 i.u. of vitamin E twice daily for 4 weeks. Endothelium-dependent and -independent vasodilatation were assessed by intrabrachial infusion of acetylcholine and sodium nitroprusside, and forearm blood flow was measured by strain-gauge plethysmography. Basal ·NO function was assessed by infusion of NG-monomethyl-l-arginine.

3.Plasma α-tocopherol concentration was enhanced after administration of vitamin E (34.6±1.8 to 86.9±9.6 ;μmol/l; P< 0.001). In addition, vitamin E administration significantly increased acetylcholine-mediated vasodilatation whether the results were expressed in terms of changes in absolute forearm blood flow (P< 0.01), forearm vascular resistance (P< 0.05) or forearm blood flow ratios (P< 0.001). Similarly, absolute forearm blood flow (P< 0.05), forearm vascular resistance (P< 0.01) and forearm blood flow ratio (P< 0.01) responses to NG-monomethyl-l-arginine were augmented by vitamin E therapy. Sodium nitroprusside responses were unaltered.

4.These results indicate that 4 weeks therapy with 1000 i.u. of vitamin E daily improves basal and stimulated ·NO-related endothelial function in subjects with hypercholesterolaemia.
Regulation of cAMP in a lymphocyte preparation isolated from peripheral venous blood in human subjects: the significance of residual thrombocytes, noradrenaline and prostaglandins
Authors: SØNDERGAARD Susanne B. , KNUDSEN Jens H. , CHRISTENSEN Niels J.
Published: August 2015

1.The aim of the study was to elucidate the mechanism of the previously reported close correlation observed between noradrenaline and cAMP in a lymphocyte preparation (LP) isolated from peripheral venous blood in healthy subjects. A close correlation was also obtained in the present study between lymphocyte noradrenaline and adrenaline and cAMP both in the basal state and after stimulation with isoproterenol (P< 0.05 to 0.007).

2.Although 99% of the thrombocytes were removed from the LP during the washing procedure, LP contained approximately one thrombocyte per lymphocyte. The noradrenaline concentration in LP which could be ascribed to residual thrombocytes, calculated from the average noradrenaline concentration in thrombocytes and the number of thrombocytes in LP, correlated closely to noradrenaline in LP (P< 0.007).

3.To test the hypothesis that noradrenaline in LP was primarily derived from plasma, we studied three patients with phaeochromocytoma, who had high levels of noradrenaline and adrenaline both in plasma and in LP.

4.Further studies showed that the addition of thrombocytes to LP increased cAMP. The response was inhibited by indomethacin, whereas the addition of cimetidine and propranolol had no effect on basal or thrombocyte-stimulated cAMP.

5.We conclude that noradrenaline in LP is a marker of the number of residual thrombocytes. The addition of thrombocytes to LP increased cAMP in lymphocytes. This response was not mediated by catecholamines but possibly by prostaglandins.
Isolation and characterization of the viscous, high-molecular-mass microbial carbohydrate fraction from faeces of healthy subjects and patients with Crohn's disease and the consequences for a therapeutic approach
Authors: RUSELER-VAN EMBDEN Johanneke G. H. , VAN LIESHOUT Leo M. C. , BINNEMA Doede J. , HAZENBERG Maarten P.
Published: August 2015

1.An earlier study by our group revealed that the viscosity of faeces from patients with Crohn's disease is significantly lower than that of healthy subjects. This is due to low concentrations of a high-molecular-mass carbohydrate, probably of bacterial origin. The cause of this phenomenon might be the impaired barrier function of the gut mucosa. Low viscosity may allow close contact of intestinal contents (bacterial products and toxins) with the intestinal wall. This could play a role in the maintenance of the disease.

2.The first aim of this study was to investigate the high-molecular-mass carbohydrate fraction, responsible for viscosity, in detail. We also tried (in a pilot study) to raise the intestinal viscosity of patients with Crohn's disease with the undegradable food additive hydroxypropylcellulose (E463), in an attempt to alleviate clinical symptoms.

3.The high-molecular-mass fraction (> 300 ;kDa) responsible for faecal viscosity was sensitive to lysozyme and contained high levels of muramic acid. It was concluded that this material consisted mainly of peptidoglycan polysaccharides and was consequently of bacterial origin. The muramic acid in material from patients with Crohn's disease was 7.5 (1.5–13.9)%, which was less than in healthy subjects [11.4 (8.5–24.1)%; P = 0.0004]. Furthermore, viscosity in material from patients with Crohn's disease was found to be half [14.9 (1.0–33.6) cP] of that found in healthy subjects [35.0 (2.7–90.7) cP; P = 0.004].

4.A daily dose of 1 ;g of hydroxypropylcellulose caused an increase in faecal viscosity in patients with Crohn's disease (from 1.4 to 2.3 cP) and in healthy subjects (from 4.9 to 7.5 cP). Faecal consistency improved in patients with Crohn's disease (from watery and loose to formed) and the defecation frequency decreased from 3–4 to about 2 times a day. No changes in defecation patterns were found in healthy subjects.

5.These data indicate that the high-molecular-mass fraction that is responsible for faecal viscosity is peptidoglycan. Furthermore, a daily dose of a hydroxypropylcellulose solution to increase the viscosity of the intestinal contents of patients with Crohn's disease might be beneficial. This approach merits further study.
Effect of sodium nitroprusside and L-arginine methyl ester on rat hearts stored at 4 °C for 24 h
Authors: FAGBEMI Oluwole S. , NORTHOVER Basil J.
Published: August 2015

1.This study examined the effects of altering nitric oxide levels with sodium nitroprusside or l-arginine in rat hearts stored hypothermically.

2.Hearts were microperfused at 4 ;°C for 24 ;h with a modified Krebs–Henseleit buffer (KHB) that contained either sodium nitroprusside, l-arginine, l-arginine methyl ester or dexamethasone.

3.After hypothermic storage, hearts were rewarmed to 37 ;°C with KHB alone or KHB containing sodium nitroprusside or l-arginine. Cardiac function was then assessed in either Langendorff mode or working heart mode.

4.Compared with values from fresh unstored hearts, hypothermic stored hearts showed a significant decrease in coronary flow and left ventricular developed pressure when the stored hearts were perfused in Langendorff mode. These hearts also produced less aortic flow and cardiac output when perfused in the working mode.

5.Hearts hypothermically microperfused with buffer containing either l-arginine or sodium nitroprusside and then reperfused in the Langendorff mode with untreated KHB buffer had the highest left ventricular developed pressure and coronary flow values. Aortic flow and cardiac output were also higher in these hearts.

6.In all groups of stored hearts, the concentrations of both ATP and creatine phosphate were significantly low, when compared with values from freshly isolated hearts. Addition of dexamethasone to the buffer either during storage or during reperfusion had no beneficial effect on high-energy phosphate loss or cardiac performance of stored hearts.

7.This study showed that the addition of nitric oxide donors to storage buffer significantly improves cardiac function on normothermic reperfusion. The improved functional recovery is unrelated to the high-energy phosphate content of these hearts.
Reproducibility of three different methods of measuring baroreflex sensitivity in normal subjects
Authors: LORD S. W. , CLAYTON R. H. , HALL M. C. S. , GRAY J. C. , MURRAY A. , McCOMB J. M. , KENNY R. A.
Published: August 2015

1.Baroreflex sensitivity is a useful tool for investigating cardiovascular reflexes in a number of clinical settings. Several different methods of measuring baroreflex sensitivity are available. In order to determine a clinically useful non-invasive method of measuring baroreflex sensitivity we compared two methods (spectral analysis and the Valsalva manoeuvre) with regard to reproducibility, agreement with a standard invasive method (phenylephrine infusion) and failure rate.

2.Twenty-six healthy subjects aged 22 to 63 years attended on three separate occasions for measurement of baroreflex sensitivity using the different methods. The effect of a recent head-up tilt on baroreflex sensitivity was measured.

3.Reproducibility was best for the low-frequency component of the spectral method [coefficient of variation 25.0% (range 3.5–42.4%)] and worst for the Valsalva method [coefficient of variation 29.3% (range 13.8–93.1%)]. Both non-invasive methods overestimated values compared with the phenylephrine method [bias of low-frequency component of the spectral method, 1.17 (0.38–3.6); bias of the Valsalva method, 1.13 (0.19–6.7)]. The high-frequency component of the spectral method did not agree with the phenylephrine method.

4.The spectral analysis method had the fewest failures (seven subjects with a failure on at least one occasion), and the phenylephrine method the most (16 subjects with a failure on at least one occasion). A short head-up tilt did not affect the subsequent non-invasive measurement of baroreflex sensitivity.

5.It was concluded that the low-frequency component of the spectral method was the most clinically useful non-invasive measurement of baroreflex sensitivity.
Aldosterone blunts the baroreflex response in man
Authors: YEE K. M. , STRUTHERS A. D.
Published: August 2015

1. Recent animal evidence suggests that aldosterone, like angiotensin II, may possess detrimental autonomic modulating properties. Aldosterone has been shown to impair the baroreflex response in animal models. This study is designed to test the hypothesis that aldosterone directly attenuates the baroreflex in vivo in man.

2. Fourteen healthy male volunteers [mean age (S.D.) 25 (9) years] received intravenous d-aldosterone (12 pmol·min-1·kg-1) and 5% dextrose (vehicle) in a double-blind crossover fashion, co-infused with incremental doses of intravenous phenylephrine and sodium nitroprusside. Aldosterone had no significant effect on resting blood pressure, heart rate or baroreflex response to sodium nitroprusside. However, reflex responses to phenylephrine were impaired with aldosterone (P< 0.01) while blood pressure responses were unaltered. Baroreflex sensitivity was significantly blunted in the aldosterone group [8.36±2.19 versus 10.12±2.27 ms/mmHg; P< 0.04].

3. This study confirms previous observations from animal models that aldosterone impairs the baroreflex response. High aldosterone levels may contribute to the baroreflex dysfunction in cardiovascular diseases such as hypertension and heart failure.
Subcutaneous glucagon-like peptide-1 (7-36) amide is insulinotropic and can cause hypoglycaemia in fasted healthy subjects
Authors: EDWARDS C. Mark B. , TODD Jeannie F. , GHATEI Mohammad A. , BLOOM Stephen R.
Published: August 2015

1. Glucagon-like peptide-1 (7-36) amide (GLP-1) is a gut hormone released postprandially that stimulates insulin secretion, suppresses glucagon secretion and delays gastric emptying. The insulinotropic action of GLP-1 is more potent under hyperglycaemic conditions. Several published studies have indicated the therapeutic potential of subcutaneous GLP-1 in non-insulin-dependent (Type 2) diabetes mellitus.

2. We investigated whether subcutaneous GLP-1, at a dose shown to improve glycaemic control in early Type 2 diabetes, is insulinotropic at normal fasting glucose concentrations. A double-blind, randomized, crossover study of 10 healthy subjects injected with GLP-1 or saline subcutaneously after a 16 h fast was performed. The effect on cardiovascular parameters was also examined.

3. GLP-1 caused a near 5-fold rise in plasma insulin concentration. After treatment with GLP-1, circulating plasma glucose concentrations fell below the normal range in all subjects. One subject had symptoms of hypoglycaemia after GLP-1. A rise in pulse rate was found which correlated with the fall in plasma glucose concentration. An increase in blood pressure occurred with GLP-1 injection which was seen at the same time as the rise in plasma GLP-1 concentrations.

4. This study indicates that subcutaneous GLP-1 can override the normal homoeostatic mechanism maintaining fasting plasma glucose in man, and is also associated with an increase in blood pressure.
Renal effects of brain natriuretic peptide in patients with congestive heart failure
Authors: JENSEN Kaare T. , EISKJÆR Hans , CARSTENS Jan , PEDERSEN Erling B.
Published: August 2015

The effect of a continuous infusion of human brain natriuretic peptide, 2 ;pmol·min-1·kg-1, during 60 ;min was studied in nine patients with congestive heart failure and in 10 healthy control subjects. Brain natriuretic peptide increased from 1.6 to 101 ;pmol/l in control subjects and from 25 to 173 ;pmol/l in congestive heart failure during infusion. Urinary sodium excretion increased significantly in both congestive heart failure (60%) and control subjects (71%), but the absolute increase was significantly lower in congestive heart failure (27 ;μmol/min) than in control subjects (190 ;μmol/min). Urinary flow rate did not change. The lithium clearance technique was used to evaluate the segmental tubular function; the distal fractional reabsorption of sodium decreased significantly less in congestive heart failure (DFRNa: -0.8%) than in control subjects (DFRNa: -3.7%). Baseline values for glomerular filtration rate and renal plasma flow were reduced in congestive heart failure, but brain natriuretic peptide induced no significant changes between congestive heart failure and control subjects. Brain natriuretic peptide induced the same absolute increase in secondary messenger cGMP in plasma and urine in both patients and healthy subjects. It is concluded that the natriuretic response to brain natriuretic peptide infusion was impaired in patients with congestive heart failure compared with healthy subjects, and it is likely that the impaired natriuretic response was caused by a reduced responsiveness in the distal part of the nephron.
Nitric oxide stimulates cyclic guanosine monophosphate production and electrogenic secretion in Caco-2 colonocytes
Authors: ROLFE V. E. , MILLA P. J.
Published: August 2015

Nitric oxide stimulates intestinal ion transport via the activation of enteric nerves, but it is not known whether it regulates intestinal transport function by acting on the epithelium directly. The aim of this study was to determine the influence of nitric oxide on epithelial electrogenic ion secretion, measured as the short-circuit current (Isc), using the human colonic carcinoma cell line Caco-2. The cellular mechanisms were examined by measuring epithelial cGMP production, and nitrite release was monitored as an index of nitric oxide synthesized. The nitric oxide substrate L-arginine methyl ester increased nitrite release, electrogenic secretion and cell cGMP production. Pretreatment with L-NAME (Nω-nitro-L-arginine methyl ester, 1 mM), but not the D-isomer, significantly reduced the electrogenic secretion and cGMP production evoked by L-arginine methyl ester, implicating nitric oxide synthase involvement. Pretreatment with cystamine, but not Methylene Blue, significantly reduced the maximum Isc and the cGMP release induced by L-arginine methyl ester and the nitric oxide donor sodium nitroprusside, implicating the involvement of particulate guanylate cyclase. In conclusion, nitric oxide stimulates electrogenic ion secretion and cGMP production in intestinal epithelial cells by activating particulate guanylate cyclase. The direct action of nitric oxide on the intestinal epithelium may be important in the regulation of intestinal transport function in health and in inflammatory bowel disease.
Change in tissue concentrations of lipid hydroperoxides, vitamin C and vitamin E in rats with streptozotocin-induced diabetes
Authors: SUN Fang , IWAGUCHI Kozue , SHUDO Reiko , NAGAKI Yoshie , TANAKA Kyoko , IKEDA Kazumi , TOKUMARU Sadako , KOJO Shosuke
Published: August 2015

The tissue concentration of lipid hydroperoxides, which was determined by a specific method involving chemical derivatization and HPLC, increased significantly in the heart, liver, kidney and muscle of diabetic rats 8 weeks after the intraperitoneal injection of streptozotocin compared with that of the control group. These results demonstrate that an enhanced oxidative stress is caused in these tissues by diabetes. Vitamin C concentrations of the brain, heart, lung, liver, kidney and plasma of the diabetic rats decreased significantly after 8 weeks compared with those of the control group. Vitamin E concentrations of the brain, heart, liver, kidney, muscle and plasma of the diabetic rats increased significantly after 4 weeks compared with the control group. After 8 weeks, an elevation in vitamin E concentration was observed in the heart, liver, muscle and plasma of the diabetic rats.
Pharmacokinetics of L-arginine during chronic administration to patients with hypercholesterolaemia
Authors: TANGPHAO Oranee , CHALON Stephan , MORENO Heitor , HOFFMAN Brian B. , BLASCHKE Terrence F.
Published: August 2015

Acute administration of L-arginine, the precursor of endothelial nitric oxide, has been shown to improve endothelial function in hypercholesterolaemic rabbits and humans. Animal studies suggest that this beneficial effect, which is thought to be related to the increased availability of nitric oxide, may not be sustained during chronic oral administration. Pharmacokinetic alterations may contribute to this observation. The present study was designed to examine the disposition of L-arginine in hypercholesterolaemic subjects during long-term administration. Plasma L-arginine concentrations were determined by HPLC in 10 patients (eight women and two men; mean age 46±16 years) after an intravenous dose of 10 or 30 g and an oral dose of 5 or 7 g. Pharmacokinetic studies were performed at regular intervals (4 weeks) during a 12-week period of oral L-arginine administration (14–21 g/day). The average plasma L-arginine concentrations before (baseline) and during administration were 16.1±1.2 and 22.5±1.3 μg/ml respectively (P< 0.05). Plasma concentrations of L-arginine remained above baseline throughout weeks 2–12. The L-arginine exposure, expressed as a normalized area-under-the-curve for 8 h (AUC0–8) after oral or intravenous doses during the first visit, was 894.4±118.7 and 1837.8±157.0 units respectively. There were no significant changes in peak plasma L-arginine concentrations or in the AUC0–8 after oral and intravenous doses during subsequent visits (P> 0.05). The mean non-renal clearance of L-arginine during the four visits remained constant. Knowledge of the pharmacokinetics of L-arginine may be useful in the design of clinical trials involving this agent, as well as in the interpretation of the pharmacodynamics of this important precursor of nitric oxide.
Genetic determinants of diabetic nephropathy
Authors: CHOWDHURY Tahseen A. , DYER Philip H. , KUMAR Sudhesh , BARNETT Anthony H. , BAIN Stephen C.
Published: August 2015

Diabetic nephropathy is the most serious complication of diabetes mellitus. Progression of the condition leads to end-stage renal failure, and other complications of diabetes are also common in this group of patients. The onset of overt albuminuria in a patient with diabetes heralds an increased risk of death, particularly from cardiovascular disease. There is considerable evidence to show that nephropathy is influenced by genetic factors. Epidemiological studies show that only a minority of patients with diabetes develop nephropathy irrespective of glycaemic control, suggesting that a subgroup of patients are at higher risk of nephropathy. Marked ethnic variation is observed, with nephropathy being more common in certain ethnic groups. Familial clustering of nephropathy is also observed. Parental history of hypertension, diabetes or cardiovascular disease appears to predispose to nephropathy in patients with diabetes. A number of methods are available to dissect polygenic disease: animal models, genetic association studies (case-control studies), affected sib-pair studies, discordant sib-pair studies and transmission distortion analysis. Most published work has been based on association studies. Association studies have shown conflicting results often due to small numbers of cases and controls, and poor phenotypic characterization. The angiotensin-converting enzyme gene insertion (I)/deletion (D) polymorphism has been studied in detail, but does not appear to be a strong risk marker for nephropathy. It does, however, appear to have a role in response to angiotensin-converting enzyme inhibition, with II homozygotes being the most responsive and DD homozygotes the least. A number of other genetic loci have also shown positive associations with nephropathy, including apolipoprotein E, heparan sulphate and aldose reductase. More recently, affected sib-pair analysis and discordant sib-pair analysis have suggested possible genetic loci on chromosomes 3, 7, 9, 12 and 20. These have yet to be reproduced in larger numbers of families, and the specific gene regions on these chromosomes remain elusive. The evidence presented in this review strongly supports the role of genetic factors in nephropathy. Detection of strong genetic risk markers for nephropathy will allow further insights into the pathogenesis of nephropathy, and possibly the development of novel therapeutic agents for its treatment. It will also allow preventive therapy to be directed at those patients with the greatest risk for development of diabetic nephropathy.
Human complex sound analysis*
Authors: GRIFFITHS T. D.
Published: August 2015

The analysis of complex sound features is important for the perception of environmental sounds, speech and music, and may be abnormal in disorders such as specific language impairment in children, and in common adult lesions including stroke and multiple sclerosis. This work addresses the problem of how the human auditory system detects features in complex sound, and uses those features to perceive the auditory world. The work has been carried out using two independent means of testing the same hypotheses; detailed psychophysical studies of neurological patients with central lesions, and functional imaging using positron emission tomography and functional magnetic resonance imaging of normal subjects. The psychophysical and imaging studies have both examined which brain areas are concerned with the analysis of auditory space, and which are concerned with the analysis of timing information in the auditory system. This differs from many previous human auditory studies, which have concentrated on the analysis of sound frequency. The combined lesion and functional imaging approach has demonstrated analysis of the spatial property of sound movement within the right parietal lobe. The timing work has confirmed that the primary auditory cortex is active as a function of the time structure of sound, and therefore not only concerned with frequency representation of sounds.