bluuebunny/crossref_metadata_2025_split huggingface dataset:
Superficial Hand Vein Responses to NG-Monomethyl-l-Arginine in Post-Partum and Non-Pregnant Women
Authors: Ford G. A. , Robson S. C. , Mahdy Z. A. 
Published: August 2015

1. During human pregnancy marked vasodilatation occurs in arterial and venous vascular beds. The mechanisms responsible for this change remain unclear. The contribution of increased nitric oxide activity to vasodilatation associated with pregnancy was determined by examining superficial hand vein responses to NG-monomethyl-l-arginine, an inhibitor of nitric oxide synthase, in post-partum women 24–48 h after delivery when vasodilatation remains at levels present during the third trimester.
2. Seventeen healthy women, 24–48 h post partum, and 13 healthy non-pregnant women were studied. Eight of the post-partum women underwent repeat studies 12–16 weeks after delivery.
3. NG-monomethyl-l-arginine (100 nmol/min) resulted in venoconstriction in non-constricted veins (baseline, 0%; 5 min, 26 ± 9%; 10 min, 14 ± 8%; 15 min, 8 ± 7%; means ± SEM) and noradrenaline-constricted veins (5 min, 30 ± 7%; 10 min, 24 ± 10%; 15 min, 14 ± 11%). No constrictor response to NG-monomethyl-l-arginine was present in the same women 12 weeks post partum (5 min, 1 ± 4%; 10 min, 0 ± 3%; 15 min, 1 ± 4%) or in the non-pregnant control subjects in non-constricted (5 min, 2 ± 3%; 10 min, 4 ± 3%; 15 min, 2 ± 2%) or noradrenaline-constricted veins (Smin, − 2 ± 7%; 10 min, 1 ± 9%; 15 min, − 5 ± 7%).
4. These findings indicate that nitric oxide activity is increased in the immediate post-partum period in venous vasculature, and support the hypothesis that increased nitric oxide activity may be responsible for the vasodilatation observed during normal pregnancy.
Acute Haemodynamic Responses and Inhibition of Tumour Necrosis Factor-α by Pentoxifylline in Rats with Cirrhosis
Authors: Soupison Thierry , Yang Song , Bernard Catherine , Moreau Richard , Kirstetter Philippe , D'Almeida Mark , Cailmail Stéphane , Tedgui Alain , Lebrec Didier 
Published: August 2015

1. Although pentoxifylline has been shown to reduce portal hypertension, the mechanism for this is unclear. Since pentoxifylline decreases tumour necrosis factor-α production and since this cytokine may induce vasodilatation per se, a pentoxifylline-induced decrease in tumour necrosis factor-α production may limit arterial vasodilatation and decrease portal pressure. The aim of the present study was to examine the effects of pentoxifylline administration on plasma tumour necrosis factor-α concentrations and haemodynamics in normal and cirrhotic rats.
2. In both groups, systemic and splanchnic haemodynamics and plasma tumour necrosis factor-α concentrations were measured before and 120 min after the administration of saline or pentoxifylline (20 mg/kg intravenous bolus).
3. In cirrhotic rats, pentoxifylline significantly decreased portal pressure (24 ± 13%) and tributary blood flow (33 ± 30%). On the other hand, pentoxifylline significantly increased vascular resistance in portal and hepatic arterial territories. Systemic haemodynamics were not altered. In normal rats, pentoxifylline significantly decreased portal pressure but induced no other significant changes in splanchnic or systemic haemodynamics. In cirrhotic rats, plasma tumour necrosis factor-α concentrations were significantly reduced after pentoxifylline administration but not after saline administration. No significant correlations were found between pentoxifylline-induced changes in tumour necrosis factor-α levels and changes in splanchnic haemodynamics. In normal rats, plasma tumour necrosis factor-α concentrations significantly decreased after pentoxifylline or saline administration.
4. This study shows that in rats with cirrhosis, pentoxifylline induces a decrease in both portal pressure and plasma tumour necrosis factor-α concentrations. These reductions were not correlated however.
Non-Invasive Measurement of Cardiac Oxygenation and Haemodynamics during Transient Episodes of Coronary Artery Occlusion and Reperfusion in the Pig
Authors: Thorniley M. S. , Lahiri A. , Glenville B. , Shurey C. , Baker G. , Ravel U. , Crawley J. , Green C. J. 
Published: August 2015

1. The non-invasive method of near-infrared spectroscopy was used to measure myocardial oxygenation and haemodynamics in response to left anterior descending coronary artery occlusion in a porcine model.
2. Near-infrared spectroscopy measures changes in haemoglobin (and myoglobin) oxygenation and blood volume to yield information on tissue perfusion and flow. It also measures the redox state of cytochrome aa3, thus providing information about intracellular oxygen utilization.
3. Left anterior descending coronary artery occlusion was induced to produce periods of ischaemia lasting between 24 s and 13.5 min (n = 13). The changes in deoxyhaemoglobin, oxyhaemoglobin and cytochrome aa3 measured during occlusion were all highly significant compared with baseline variation. In all occlusions (n = 13) a rapid decrease in oxyhaemoglobin concentration (−75.83 ± 3.27 μmol/l, mean ± SEM) with a simultaneous increase in deoxyhaemoglobin of 9.27 ± 1.69 μmol/l was measured. The total haemoglobin concentration also fell by −71.3 ± 5.32 μmol/l. Cytochrome aa3 was also reduced during occlusion (–8.35 ± 1.044) μmol/l.
4. Over the range 24–60 s occlusion, the magnitude of the fall in total haemoglobin and oxyhaemoglobin correlated with the duration of occlusion (P &gt; 0.003 and 0.013 respectively). For total haemoglobin only the magnitude of the fall correlated with the increase upon release of occlusion (r = 0.89, P &gt; 0.003).
5. Release of occlusion (n = 8) resulted in an immediate increase in the concentration of deoxyhaemoglobin at 9.88 ± 1.06 s, then total haemoglobin at 13.62 ± 1.23 s and finally oxyhaemoglobin at 29.75 ± 5.96 s. The difference between the timing of the maxima after reperfusion is significant (P &gt; 0.002 and P &gt; 0.007 respectively). Moreover, the time for the deoxyhaemoglobin signal to reach maximum values was found to correlate with the duration of occlusion (P &gt; 0.04). This could be indicative of the Po2 of the ischaemic tissues and an immediate off-loading of oxygen from oxyhaemoglobin. The results are reliable, reproducible and sensitive enough to detect the kinetics of haemoglobin oxygenation from a beating heart in situ.
Abnormal Baroreceptor—Cardiac Reflex Sensitivity is Not Detected by Conventional Tests of Autonomic Function in Patients with Insulin-Dependent Diabetes Mellitus
Authors: Weston Philip J. , James Martin A. , Panerai Ronnie , McNally Paul G. , Potter John F. , Thurston Herbert , Swales John D. 
Published: August 2015

1. Autonomic neuropathy is a common complication of diabetes mellitus and is a major risk factor for sudden death.
2. A group of 30 patients with insulin-dependent diabetes mellitus and 30 age-, sex- and blood pressure-matched control subjects underwent traditional tests of autonomic function. Resting supine R—R interval and systolic blood pressure variability were assessed using spectral analysis methods. In addition, we assessed the baroreceptor—cardiac reflex from the linear relation of the change in R—R interval to the increasing systolic blood pressure measured noninvasively with the Finapres monitor during phase 4 of the Valsalva manoeuvre and from resting heart rate and systolic blood pressure power spectra.
3. Whereas standard tests of autonomic function revealed no differences between patients with insulin-dependent diabetes mellitus and control subjects, there was a significant reduction in power spectral density of heart rate variability around the high-frequency region (125.2 ± 112.9 versus 459.3 ± 189.8 ms2, mean ± SD). Furthermore, reductions in baroreflex sensitivity calculated from the Valsalva manoeuvre were detected in diabetics compared with controls (3.3 ± 1.6 versus 9.5 ± 2.5 ms/mmHg, mean ± SD, P &gt; 0.00001). There were significant relations between impairment of the baroreflex and duration of diabetes (P &gt; 0.001) and poor diabetic control (P &gt; 0.05).
4. In summary, autonomic dysfunction occurs much more frequently in diabetic patients than conventional tests would suggest. Abnormal baroreceptor—cardiac reflex sensitivity in patients with insulin-dependent diabetes mellitus may in part be explained by abnormal parasympathetic function. This unrecognized abnormality may have a role in the increased incidence of sudden death seen in young diabetic subjects.
Potential Confounding Effect of Hand-Warming on the Measurement of Insulin Sensitivity
Authors: Petrie John R. , Ueda Shinichiro , Morris Andrew D. , Elliott Henry L. , Connell John M. C. 
Published: August 2015

1. Hand-warming is employed during metabolic studies to ‘arterialize’ venous blood, but also has systemic haemodynamic effects. Study 1 aimed to determine if hand-warming affects the value for whole-body insulin sensitivity derived from the hyperinsulinaemic euglycaemic clamp technique. Study 2 was designed to assess the effect of hand-warming on contralateral forearm blood flow.
2. In study 1, eight healthy male subjects attended for four modified euglycaemic clamp studies, during which the right hand was placed in a heated-air hand box (55°C), and the glucose infusion rate was adjusted according to blood samples from a cannula in either an ipsilateral dorsal hand vein or a contralateral antecubital vein with the box switched either on or off. In study 2, five healthy subjects attended two study days when the effect of 2h of hand-warming (or control) on contralateral forewarm blood flow was measured.
3. Study 1: when clamps were performed according to samples taken from the contralateral antecubital vein, insulin sensitivity values were significantly lower during box-on versus box-off clamps (mean ± SD 10.2 ± 3.0 versus 13.0 ± 3.8 ingrain−1 kg−1, P &gt; 0.05, 95% confidence interval −0.2, −5.3). When clamps were performed according to samples taken from the ipsilateral hand, there was no difference in insulin sensitivity during box-on versus box-off clamps (9.2 ± 2.1 versus 9.0 ± 1.7 mg min−1 kg−1, P not significant, 95% confidence interval −0.5, +0.9). There was a mean increase in heart rate of 6 beats/min in the box-on conditions (P &gt; 0.05, analysis of variance). Study 2: forearm blood flow in the contralateral arm during hand-warming was significantly higher than in the control condition (P &gt; 0.05, analysis of variance), although heart rate was similar on both study days.
4. Hand-warming had a detectable effect on insulin sensitivity when clamps were performed according to samples withdrawn from the contralateral arm, but no measurable effect when clamps were performed in the conventional manner. In addition, hand-warming increased heart rate during hyperinsulinaemia and contralateral FBF under basal conditions. These findings raise concern about unwanted (potentially confounding) systemic haemodynamic effects of hand-warming on the measurement of insulin sensitivity and insulin-mediated vasodilatation.
Effects of Vitamin E Supplementation on Erythrocyte Antioxidant Defence Mechanisms of Smoking and Non-Smoking Men
Authors: Brown K. M. , Morrice P. C. , Arthur J. R. , Duthie G. G. 
Published: August 2015

1. During all aerobic metabolism, free radicals generated by the partial reduction of oxygen are potentially injurious to cells. Highly efficient antioxidant defence systems exist to inhibit oxidative damage to cellular lipids and proteins. Specific enzymes have a crucial role in these antioxidant defences, and their activity may be induced by regulatory mechanisms that respond to oxygen metabolite concentration.
2. To assess whether smoking induces an additional adaptive response, we compared antioxidant defence systems in erythrocytes from smokers and non-smokers and assessed whether a high intake of vitamin E (280 mg/day), a major lipophilic free-radical-scavenging antioxidant, affects the activity of antioxidant enzymes.
3. A total of 100 men, 50 smokers and 50 non-smokers, were allocated to four treatment groups in a 2 × 2 factorial design (smokers versus non-smokers and placebo versus vitamin E). For 10 weeks each subject took one capsule per day of either 280 mg dl-α-tocopherol acetate or a visually identical placebo (hydrogenated coconut oil with negligible vitamin E content).
4. Despite increased erythrocyte cytosolic antioxidant enzyme activities in smokers compared with non-smokers, erythrocytes from smokers were more susceptible to hydrogen peroxide-induced lipid peroxidation in vitro.
5. Vitamin E supplementation further increased erythrocyte catalase (EC 1.11.1.6) activity in both smokers and non-smokers (P &gt; 0.001) and erythrocyte glutathione peroxidase (EC 1.11.1.9) and glutathione reductase (EC 1.6.4.2) activities in non-smokers (P &gt; 0.001). After supplementation with vitamin E there was a concomitant fall in erythrocyte superoxide dismutase (EC 1.15.1.1) activity (P &gt; 0.001) and total glutathione concentration (P &gt; 0.01). Furthermore, in both smokers and non-smokers there was a significant decrease in the susceptibility of erythrocytes to peroxidation (P &gt; 0.001).
6. Various endogenous and exogenous factors exert control over cellular protection against reactive oxygen species, and our data suggest that one such factor is the supply of vitamin E.
Peripheral Haemodynamics and Renal Function in Relation to the Menstrual Cycle
Authors: Van Beek E. , Houben A. J. H. M. , Van Es P. N. , Willekes C. , Korten E. C. C. M. , De Leeuw P.W. , Peeters L. L. H. 
Published: August 2015

1. The objective of this study was to investigate whether the luteal phase of the menstrual cycle differs from the follicular phase by the development of a state of general vascular relaxation.
2. Once in the follicular and once in the luteal phase of the menstrual cycle, we measured by non-invasive techniques: arterial blood pressure (by finger blood pressure measurements), vascular tone (by pulse-wave velocity and plethysmography), blood flow to skin (by laser-Doppler), blood flow to forearm (by plethysmography) and blood flow to kidneys (by para-aminohippurate clearance), and the glomerular filtration rate (by inulin clearance). The data points obtained in the luteal phase were compared with those in the follicular phase by non-parametric tests.
3. Arterial blood pressure, vascular tone and the blood flows to the forearm and kidneys were comparable in the two phases of the menstrual cycle. In contrast, the blood flow to the skin was consistently lower, and the glomerular filtration rate higher in the luteal phase of the menstrual cycle.
4. The results of the present study do not support our hypothesis of a general vascular relaxation in the luteal phase of the menstrual cycle. The lower skin flow in the luteal phase may be an adaptation needed to ensure the higher core temperature of 0.3–0.5°C in the luteal phase. The higher glomerular filtration rate was in most cases paralleled by a higher renal blood flow in the luteal phase. This suggests that the higher glomerular filtration rate is secondary to a selective vasorelaxation of the afferent renal arterioles.
Behaviour of Adrenomedullin during Acute and Chronic Salt Loading in Normotensive and Hypertensive Subjects
Authors: Ishimitsu Toshihiko , Nishikimi Toshio , Matsuoka Hiroaki , Kangawa Kenji , Kitamura Kazuo , Minami Jun-Ichi , Matsuo Hisayuki , Eto Tanenao 
Published: August 2015

1. Responses of adrenomedullin to acute and chronic salt loading were examined in normotensive and hypertensive subjects.
2. In the acute salt load study, isotonic saline (50 ml/kg for 1 h) was intravenously infused into nine normotensive subjects and 11 patients with essential hypertension. Plasma adrenomedullin was higher in hypertensive than in normotensive subjects but was unchanged by saline infusion in either the normotensive (before infusion, 2.4 ± 0.2 fmol/ml; after infusion, 2.4±0.1 fmol/ml) or hypertensive (before infusion, 3.0±0.1 fmol/ml; after infusion, 2.9 ± 0.2 fmol/ml) group, while renin was suppressed and atrial natriuretic peptide was markedly increased. Plasma endothelin was not affected either.
3. In the chronic salt load study, seven normotensive subjects and 23 patients with essential hypertension underwent two 7-day periods of 30 and 260 mmol/day sodium intake. Depending on the blood pressure change, 13 hypertensive subjects were classified as salt-resistant and 10 as salt-sensitive. Salt-sensitive hypertensive subjects had suppressed plasma renin activity even during low salt intake. Plasma adrenomedullin or endothelin were not affected by the salt intake changes in any group; however, the high salt intake increased atrial natriuretic peptide in all groups.
4. These data indicate that the circulating level of adrenomedullin is not changed by either acute or chronic salt loading in normotensive subjects and patients with essential hypertension.
Impairment of Intracellular Calcium Homoeostasis in the Exocrine Pancreas after Caerulein-Induced Acute Pancreatitis in the Rat
Authors: Bragado M. J. , Roman J. I. San , González A. , García L. J. , López M. A. , Calvo J. J. 
Published: August 2015

1. We have measured intracellular calcium concentrations in basal conditions and in response to cholecystokinin-octapeptide and acetylcholine in pancreatic acini isolated from rats with caerulein-induced acute pancreatitis and compared them with those in control rats.
2. We also measured amylase secretion in basal conditions and in response to cholecystokinin-octapeptide in both groups.
3. In pancreatic acini from rats with pancreatitis the basal intracellular calcium concentration was significantly increased (134.9±7.1 nmol/l compared with 71.8 ± 2.9 nmol/l, P &lt; 0.001). Moreover, the maximum values of intracellular calcium attained during the stimulation period were equivalent in acini from control and pancreatitic rats with no statistically significant differences.
4. In acini from control rats the differences between the resting levels of intracellular calcium and the maximum intracellular calcium values (Δ[Ca2+]i) in response to several concentrations of cholecystokinin-octapeptide showed a clear dose—response relationship, with a half-maximal increase at 0.1 nmol/l and a maximal difference (Δ[Ca2+]i = 259 ±50 nmol/l) at 1 nmol/l. In contrast, a right-shifted response, with a statistically significant smaller increase, was observed in acini from pancreatitic rats.
5. Basal amylase release was significantly higher in acini from rats with pancreatitis (11.7 ±1.0% of total compared with 5.9 ±1.1% of total, P &lt; 0.001). In contrast, cholecystokinin-octapeptide and acetylcholine-evoked amylase secretion was reduced by more than 85% in acini from pancreatitic rats.
6. In conclusion, calcium homoeostasis in pancreatic acinar cells from rats with caerulein-induced pancreatitis seems to be impaired. These results suggest excessive release of acinar free ionized calcium, or damage to the integrity of mechanisms that restore low resting levels of intracellular free ionized calcium, and the consequent calcium toxicity could be the key trigger in caerulein-induced acute pancreatitis.
Suppression of Oxidant Production by Diltiazem, Nifedipine and Verapamil in Human Neutrophils
Authors: Feng Y.-H. , Hart G. 
Published: August 2015

1. Polymorphonuclear leucocytes are a major source of toxic oxidants in vivo, causing tissue injury in certain circumstances such as ischaemia and reperfusion. Calcium ions are a key mediator in the production of oxidants by these cells. The aim of this study was to examine the effects of the widely used calcium antagonists diltiazem, nifedipine and verapamil on the production of oxidants in neutrophils.
2. Human neutrophils were freshly prepared, suspended in different luminol media and mixed with varying amounts of each calcium antagonist. They were then stimulated with either serum-opsonized zymosan or phorbol 12-myristate 13-acetate. Oxidant production was determined by three methods, namely luminol-enhanced chemiluminescence, oxygen consumption and cytochemical staining.
3. Calcium antagonists inhibited oxidant production by neutrophils. IC50 values for diltiazem, nifedipine and verapamil in calcium-free medium were 0.32 mmol/l (SEM 0.02), 0.27 mmol/l (SEM 0.02) and 0.24 mmol/l (SEM 0.02) respectively under zymosan stimulation, and 0.33 mmol/l (SEM 0.02), 0.26 mmol/l (SEM 0.02) and 0.13 mmol/l (SEM 0.07) respectively under phorbol 12-myristate 13-acetate stimulation. These effects were independent of the presence of Ca2+ in the extracellular solution. Some inhibition was also observed when the calcium antagonists were added during the course of a respiratory burst. Oxygen uptake by the cells was reduced in the presence of each calcium antagonist. Phagocytosis by the stimulated neutrophils was not affected despite inhibition of oxidant production.
4. We conclude that calcium antagonists can suppress the capacity of neutrophils to produce oxidants. This result may provide a novel explanation for the observation that delayed treatment with calcium antagonists may attenuate post-ischaemic myocardial dysfunction.
Lymphocyte cAMP and Ageing: Significance of Subset Composition, Plasma Noradrenaline, Regular Physical Training and Long-Term Smoking
Authors: Knudsen J. H. , Gustafsson F. , Toft J. , Christensen N. J. 
Published: August 2015

1. We studied 37 healthy men at rest in the supine position to examine the effect of ageing, smoking and physical training on β2-adrenoceptor function, plasma catecholamines and the proportions of various lymphocyte subsets.
2. In 14 young subjects the proportion of natural killer cells was correlated with cAMP production in lymphocytes and inversely correlated with plasma noradrenaline level.
3. In 16 elderly non-smokers plasma noradrenaline was negatively correlated with the natural killer cell subset CD3–CD16+. Lymphocyte cAMP responses did not differ between young and elderly non-smokers, whereas plasma noradrenaline increased slightly but significantly with age. Physical training did not influence either plasma noradrenaline or adrenaline at rest or cAMP in lymphocytes.
4. In seven elderly long-term smokers cAMP production and the viability of lymphocytes were reduced. Plasma noradrenaline attained its highest values in long-term smokers.
5. It is concluded that cAMP production and plasma noradrenaline are related to lymphocyte subset composition. The greater the proportion of natural killer cells and related subsets, the higher is cAMP production and the lower is plasma noradrenaline. Thus, the inverse correlation between lymphocyte cAMP and plasma noradrenaline is indirect and most likely mediated by variability in lymphocyte subset composition. In elderly subjects, reduced cAMP production was observed in long-term smokers, and this abnormality was probably due to a reduced viability of lymphocytes and especially of natural killer cells. The negative correlation between the proportion of natural killer cells and plasma noradrenaline at rest contrasts with a well-known mobilizing effect of adrenaline on natural killer cells.