bluuebunny/crossref_metadata_2025_split huggingface dataset:
The hyperinsulinaemic–euglycaemic glucose clamp: reproducibility and metabolic effects of prolonged insulin infusion in healthy subjects
Authors: SOOP Mattias , NYGREN Jonas , BRISMAR Kerstin , THORELL Anders , LJUNGQVIST Olle 
Published: August 2015

To examine the reproducibility of the hyperinsulinaemic–euglycaemic clamp technique at mid-physiological hyperinsulinaemia, seven healthy subjects {age 50 (25, 59) years [median (range)], body mass index 23.1 (20.8, 25.5) kg·m-2} were investigated with three 2 h hyperinsulinaemic (60 µmol·l-1)–euglycaemic (4.5 mmol·l-1) clamps performed 48 h and 14 days apart respectively. The third clamp was prolonged to 8 h in order to examine effects on glucose disposal during prolonged clamps. The glucose infusion rates (GIRs) during the three 2 h clamps were 7.41 (4.28, 10.96), 7.26 (5.38, 11.02) and 6.63 (4.42, 10.3) mg·kg-1·min-1, with a median intra-individual coefficient of variation of 5.8 (2.6, 22) %. During the 8 h clamp a highly variable gradual increase in GIR was observed, reaching a plateau between 4 and 5 h at 32 (5, 101) % above the GIR between 1 and 2 h (P &lt; 0.05). This increase was correlated inversely with the GIR between 1 and 2 h (r = -0.82; P &lt; 0.05), and directly with age (r = 0.86; P &lt; 0.05). Carbohydrate oxidation measured by indirect calorimetry was stable during the repeated 2 h clamps and the 8 h clamp. Endogenous glucose production measured by infusion of [6,6-2H2]glucose was suppressed during the 8 h clamp. The 2 h hyperinsulinaemic–euglycaemic clamp is reproducible at a mid-physiological range of hyperinsulinaemia. If prolonged, it results in a delayed increase in non-oxidative glucose disposal, which is most pronounced in subjects with low insulin sensitivity. The findings underline the importance of selecting age-matched controls in studies of insulin resistance.
Ethanol effects on cardiomyocyte contractility
Authors: DELBRIDGE Leanne M. D. , CONNELL Pamela J. , HARRIS Peter J. , MORGAN Trefor O. 
Published: August 2015

Little is known about the direct cardiac effects of socially common sub-intoxication levels of ethanol. Previous studies evaluating the responses of normal cardiomyocytes to short-term ethanol exposure have utilized ethanol concentrations equivalent to extreme intoxication or lethal levels in vivo. The purpose of the present study was to investigate the contractile responses of isolated rat ventricular cardiomyocytes during exposure to relatively low concentrations of ethanol in the range 0.05–0.5% (v/v) (8.6–86 mM) under physiological conditions (3 Hz stimulation; 36 °C; BSA vehicle). High-speed imaging techniques were used to study the kinetics of myocyte contraction, and shortening parameters were calculated for mechanistic evaluation. The concentration–response relationship was not linear and exhibited two plateau phases, suggesting at least two mechanisms of action of ethanol on cardiomyocyte contraction. At 0.05% (8.6 mM), ethanol treatment produced a 14.4% decrease in maximum myocyte shortening. The maximum rates of cell shortening and lengthening were similarly impaired, but there was no effect on contraction cycle timing at this low concentration. At 0.30% (51 mM), ethanol reduced maximum shortening by 40.2%, prolonged excitation–contraction coupling latency and abbreviated the contraction cycle time by 38%. The inotropic modulatory effect of ethanol was exaggerated in the absence of protein in the superfusion buffer. This is the first report which identifies ethanol at 0.05% (v/v) as a modulator of cardiac contractility. Kinetic analyses indicate that the mechanism of action involves disturbance of sarcoplasmic reticulum function, and this may contribute to arrhythmogenic vulnerability – especially in an in vivo context of heightened compensatory sympathetic drive.
α2-Macroglobulin, the main serum antiprotease, binds β2-microglobulin, the light chain of the class I major histocompatibility complex, which is involved in human disease
Authors: GOUIN-CHARNET Annie , LAUNE Daniel , GRANIER Claude , MANI Jean-Claude , PAU Bernard , MOURAD Georges , ARGILÉS Àngel 
Published: August 2015

β2-Microglobulin, a 12 kDa protein forming part of the class I HLA (histocompatibility locus antigen) major histocompatibility complex, has been used as a prognosis factor for multiple myeloma and as a marker of renal function, and has been shown to be involved in the pathogenesis of dialysis-related amyloidosis. α2-Macroglobulin has the ability to bind a wide range of physiologically important molecules, thereby influencing their metabolic impact. In this study we show by Western blotting analysis that β2-microglobulin binds to α2-macroglobulin in vitro. This binding was confirmed by BIAcore analysis, and was shown by ELISA to be concentration-dependent. The sequences of the binding peptides in the mature β2-microglobulin molecule were identified by Spot multiple peptide synthesis and α2-macroglobulin binding studies. In conclusion, β2-microglobulin interacts specifically with the universal antiprotease a2-macroglobulin. The identification of this interaction brings into question some of the axioms on the metabolism of β2-microglobulin, and may help to explain the clinical findings observed in b2-microglobulin-related diseases.
Comparative physiological study of arbutamine with exercise in humans
Authors: LOVELL Sharon L. , MAGUIRE Suzanne M. , TURTLE Frances , McDOWELL Garry , CAMPBELL Norman P. S. , RILEY Marshall S. , NICHOLLS D. Paul 
Published: August 2015

Pharmacological stress testing may be used in the diagnosis of coronary artery disease when there are contra-indications to the use of conventional exercise protocols.The responses to such testing using arbutamine and to conventional treadmill exercise were compared in eight patients. Respiratory gas analysis and cardiovascular observations were performed during both tests. For an equivalent increment in heart rate, both protocols increased systolic blood pressure and serum lactate. Minute ventilation and oxygen consumption also rose during both protocols, but much more so with exercise. The end-tidal partial pressure of CO2 [35.1 (S.D. 3.1) to 30.8 (6.6) mmHg] and the dead space/tidal volume ratio (VD/VT) [0.37 (0.09) to 0.33 (0.08)] fell significantly during arbutamine infusion, but the respiratory exchange ratio did not change during either protocol. Oxygen pulse, a marker of stroke volume, did not change significantly after arbutamine, but rose markedly after exercise [arbutamine, 3.9 (1.1) to 3.37 (0.7) ml·min-1·beat-1; exercise, 4.7 (1.4) to 16.1 (4.6) ml·min-1·beat-1 (P < 0.0001 compared with baseline); difference between peak responses: P < 0.0001]. We conclude that arbutamine simulates some of the physiological responses to exercise, although a number of these responses are less marked than during conventional exercise, in particular cardiac output (oxygen pulse). An increase in ventilation is produced, possibly due to direct stimulation of arterial chemoreceptors. These data suggest that the main action of arbutamine is to increase central drive rather than to establish peripheral demand.
Endothelial dysfunction as a possible link between C-reactive protein levels and cardiovascular disease
Authors: CLELAND Stephen J. , SATTAR Naveed , PETRIE John R. , FOROUHI Nita G. , ELLIOTT Henry L. , CONNELL John M. C. 
Published: August 2015

Low-grade chronic inflammation, characterized by elevated plasma concentrations of C-reactive protein (CRP), is associated with an increased risk of atherosclerotic cardiovascular disease. Endothelial cell activation is an early event in atherogenesis, and previous studies have reported correlations between indirect markers of endothelial cell activation and CRP concentration. Therefore, in the present study, we measured CRP concentration (and leptin concentration as an index of fat mass) in nine healthy subjects (mean age 53±8.1 years; body mass index 27±3.2 kg/m2; mean arterial blood pressure 101±9.0 mmHg) undergoing measurement of basal endothelial nitric oxide (NO) synthesis using intra-brachial infusions of NG-monomethyl-l-arginine (l-NMMA; a substrate inhibitor of endothelial NO synthase) and noradrenaline (a non-specific control vasoconstrictor). In univariate analysis, CRP concentration was correlated with (i) the percentage decrease in forearm blood flow (FBF) during l-NMMA infusion (r = 0.85, P = 0.004); and (ii) the serum leptin concentration (r = 0.65, P = 0.05). In multivariate analysis, the relationship between CRP concentration and the FBF response to l-NMMA remained significant when age and leptin (t = 2.65, P = 0.045), age and BMI (t = 3.69, P = 0.014), or age and low-density-lipoprotein-cholesterol plus high-density-lipoprotein-cholesterol (t = 3.37, P = 0.044), were included in regression models. In contrast, the response of FBF to noradrenaline was not significantly related to CRP concentration. These data demonstrate for the first time a relationship between low-grade chronic inflammation and basal endothelial NO synthesis (measured using an invasive method), and support the notion that endothelial dysfunction is a critical intermediate phenotype in the relationship between inflammation and cardiovascular disease.
The increase in sympathetic nerve activity after glucose ingestion is reduced in type I diabetes
Authors: FAGIUS Jan , BERNE Christian 
Published: August 2015

Food intake is followed by an increase in baroreflex-governed sympathetic outflow to muscle vessels. It is established that insulin contributes to this stimulation; however, the increase occurs (to a lesser degree) even in the absence of enhanced insulin secretion. To further elucidate the role of insulin, muscle nerve sympathetic activity was recorded by microneurography, and the increase after an oral 100-g glucose load in eight C-peptide-negative patients with type I diabetes without any signs of neuropathy was compared with that in 16 healthy control subjects. The level of sympathetic activity at rest was similar in the two groups (type I diabetes patients, 19.5±2.4 bursts/min; controls, 20.4±4.8 bursts/min; means±S.D.). Following glucose intake there was a significant increase in activity in both groups, with maximum values at 30 min of 24.3±3.7 bursts/min for type I diabetes patients and 34.4±9.1 bursts/min for controls. The summarized response (during 90 min) of the diabetic patients was less than half that of the control subjects (P = 0.0003). It is concluded that the response of muscle nerve sympathetic activity to glucose ingestion is reduced to about half of its normal strength in the absence of insulin, and that there is no difference in sympathetic outflow at rest between healthy subjects and diabetic patients without polyneuropathy.
Effects of the Japanese herbal medicine ‘Inchinko-to’ (TJ-135) on concanavalin A-induced hepatitis in mice
Authors: YAMASHIKI Masayoshi , MASE Akihito , ARAI Ichiro , HUANG Xian-Xi , NOBORI Tsutomu , NISHIMURA Akira , SAKAGUCHI Seigo , INOUE Kyoichi 
Published: August 2015

Inchinko-to (TJ-135) is a herbal medicine consisting of three kinds of crude drugs, and in Japan it is administered mainly to patients with cholestasis. The present study evaluated the effects of TJ-135 on concanavalin A (con A)-induced hepatitis in mice in vivo and con A-induced cytokine production in vitro. When mice were pretreated with oral TJ-135 for 1 week before intravenous con A injection, the activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) were significantly decreased 8 h after con A administration (-82%, -96% and -66% respectively). In histological investigations, sub-massive hepatic necrosis accompanying inflammatory cell infiltration was not observed in mice pretreated with TJ-135. Serum levels of interleukin-12 (IL-12), interferon-γ (IFN-γ) and IL-2 were significantly lower in mice pretreated with TJ-135 compared with controls, while IL-10 levels were higher in these mice. Intrasplenic IL-12 levels were significantly lower in mice pretreated with TJ-135, while intrasplenic IL-10 levels were higher in these mice. In vitro, IL-10 production by splenocytes was increased by the addition of TJ-135 to the culture medium, whereas the production of IL-12 and IFN-γ was inhibited. These results suggest that con A-induced hepatitis was ameliorated by pretreatment with TJ-135. With regard to the mechanism of these effects of TJ-135, we speculate that TJ-135 inhibits the production of inflammatory cytokine and enhances the production of anti-inflammatory cytokines. Therefore administration of TJ-135 may be useful in patients with severe acute hepatitis accompanying cholestasis or in those with autoimmune hepatitis.
Pharmacokinetics of retinyl palmitate and retinol after intramuscular retinyl palmitate administration in severe malaria
Authors: DAVIS Timothy M. E. , BINH Tran Quang , THU Le The Anh , ROSSI Ric , DANH Phan Thi , BARRETT P. Hugh R. , BEILBY John 
Published: August 2015

Retinol (vitamin A alcohol) is an accepted adjunctive treatment in infections such as measles. There is also indirect evidence from in vitro, animal and human studies that retinol supplementation may be beneficial in severe malaria. There have, however, been no studies that have examined the pharmacokinetics of acute retinol supplementation in severe illness. To establish whether mobilization of intramuscular retinyl palmitate (RP) and its availability as retinol are adequate in complicated falciparum malaria, we administered a single dose of 400000 i.u. of RP to six Vietnamese adults with severe malaria. Another 28 patients were not given RP. All patients had blood samples taken over 96 h for RP and retinol assay using HPLC, and received conventional anti-malarial and supportive therapy. Admission serum retinol concentrations were below the lower limit of the reference range (< 1.0 µmol/l) in 74% of the 34 patients. In supplemented patients, analysis of serum RP between 0 and 96 h using a multi-compartmental model revealed a median (range) delay in mobilization of 6.9 h (0.7–15.1 h), a bioavailability of 55% (19–100%) and an elimination half-life of 13.5 h (4.2–23.7 h). The area under the serum retinol curve expressed as an absolute or percentage change from baseline was greater in supplemented than in unsupplemented patients (P < 0.05). The separation in median serum retinol concentrations in the two groups was maximal at 48 h. The model-derived retinol half-life [1.5 (0.7–15.8) h] suggested rapid uptake, metabolism and/or excretion. In conclusion, there is variable RP bioavailability in severe malaria, but a significant if delayed increase in serum retinol over that associated with recovery from the infection. In severe infections, RP supplementation appears simple, well tolerated and of potential benefit once anti-microbial and supportive therapy have been established.
Plasma bradykinin levels in human chronic congestive heart failure
Authors: CUGNO Massimo , AGOSTONI Piergiuseppe , BRUNNER Hans R. , GARDINALI Marco , AGOSTONI Angelo , NUSSBERGER Jürg 
Published: August 2015

Induction of congestive heart failure by high-frequency pacing has been reported to increase plasma levels of immunoreactive kinins in dogs. In the present study, we evaluated plasma bradykinin levels in human heart failure. Utilizing a recently developed method, we specifically measured plasma levels of bradykinin-(1–9) nonapeptide in 21 patients with chronic congestive heart failure [New York Heart Association (NYHA) stages III and IV). At the same time, we measured plasma atrial natriuretic peptide levels and plasma renin activity, and, as a marker of inflammation, plasma levels of tumour necrosis factor. In addition, 18 healthy subjects matched for gender and age served as normal controls. Plasma bradykinin concentrations were not higher in patients with chronic congestive heart failure (median 2.1 fmol/ml) than in healthy subjects (2.6 fmol/ml). In contrast, plasma atrial natriuretic peptide levels were clearly higher (patients, 63 fmol/ml; controls, 24 fmol/ml; P < 0.0001), despite diuretic treatment and in the presence of high plasma renin activity (patients, 13.0 ng·h-1·ml-1; controls, 0.3 ng·h-1·ml-1; P < 0.0001). Tumour necrosis factor was elevated in heart failure patients in NYHA class IV only (27 pg/ml, compared with 21 pg/ml in controls; P = 0.013). Bradykinin, atrial natriuretic peptide and plasma renin activity levels were not correlated with the severity of the disease, as assessed by NYHA classification. These results indicate that a rather selective cytokine activation, without concomitant stimulation of the kallikrein–kinin system, occurs in human chronic congestive heart failure.
Induction of the stress response increases interleukin-6 production in the intestinal mucosa of endotoxaemic mice
Authors: WANG Quan , SUN Xiaoyan , PRITTS Timothy A. , WONG Hector R. , HASSELGREN Per-Olof 
Published: August 2015

Previous studies suggest that production of interleukin-6 (IL-6) is increased in the intestinal mucosa during sepsis and endotoxaemia. We tested the hypothesis that mucosal IL-6 production during endotoxaemia is increased further by the heat-shock (stress) response. The stress response was induced in mice by hyperthermia (rectal temperature of 42 °C for 3 min) or by intraperitoneal injection of sodium arsenite (10 mg/kg). At 2 h after induction of the stress response, groups of mice were injected subcutaneously with endotoxin (10 mg/kg) or sterile saline. IL-6 mRNA and protein levels in the jejunal mucosa were determined by an RNase protection assay and an ELISA respectively, and levels of hsp72 (heat-shock protein of 72 kDa) were determined by Western blot analysis. Hyperthermia and sodium arsenite increased hsp72 levels in the intestinal mucosa. IL-6 concentrations were increased in the jejunal mucosa of endotoxaemic mice, and this effect of endotoxaemia was potentiated by the stress response. Mucosal IL-6 mRNA levels were increased in endotoxaemic mice, and were increased further by the stress response. Thus it is concluded that mucosal IL-6 production during endotoxaemia may be further stimulated by the stress response. Increased IL-6 levels in the intestinal mucosa may be a potential mechanism by which the stress response exerts a protective effect during sepsis and endotoxaemia.
Role of the l-arginine/nitric oxide pathway in ischaemic/reoxygenation injury of the human myocardium
Authors: ZHANG Jin-Gang , GALIÑANES Manuel 
Published: August 2015

The role of the L-arginine/nitric oxide (NO) pathway in myocardial ischaemic/reperfusion injury remains controversial in experimental animal models. The aim of the present studies was to investigate the role of this pathway in the human myocardium. Myocardial specimens from right atrial appendages of patients undergoing elective coronary bypass graft surgery were incubated in crystalloid buffer at 37 °C and subjected to 120 min of simulated ischaemia followed by 120 min of reoxygenation. Tested drugs were added 15 min before ischaemia, and maintained during ischaemia and throughout reoxygenation. Ischaemia resulted in severe myocardial damage, as assessed by the leakage of lactate dehydrogenase (LDH) into the incubation medium and by the capacity of the tissue to reduce 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) to formazan product. L-Arginine (10 mM), a precursor of NO, significantly decreased LDH leakage (from 9.0±0.6 to 5.3±0.3 units/g wet wt; P < 0.05), but had no effect on MTT reduction or oxygen consumption. D-Arginine (10 mM), NG-nitro-L-arginine methyl ester (L-NAME; 0.5 mM), an NO synthase inhibitor, and S-nitroso-N-acetylpenicillamine (at 1, 100, 500 and 1000 µM), an NO donor, had no significant effects on the measured indices, and L-NAME did not reverse the protection afforded by L-arginine against LDH leakage. In addition, the formation of nitrotyrosine was not influenced by ischaemia/reoxygenation alone or by the agents investigated. In conclusion, these data suggest that L-arginine affords modest protection against ischaemic/reoxygenation injury of the human myocardium, an action that is NO-independent, and that NO metabolism does not play a significant role in this model.
Resting peripheral blood flow in normal pregnancy and in pre-eclampsia
Authors: ANIM-NYAME N. , SOORANNA S. R. , JOHNSON M. R. , GAMBLE J. , STEER P. J. 
Published: August 2015

Multiple organ dysfunction followed by end organ failure occurs in pre-eclampsia. While one would intuitively reason that one of the factors contributing to the end organ failure is poor nutritional blood flow, this has yet to be demonstrated. The aim of the present study was to determine whether changes in resting nutritional blood flow occur in pre-eclampsia. We used strain-gauge plethysmography to study calf blood flow in 19 women with pre-eclampsia, 13 normal pregnant women and 17 non-pregnant controls. We reasoned that, since the calf comprises mostly skeletal muscle, without anastomotic channels, blood flowing through this region would primarily reflect nutritive flow. Calf blood flow was significantly reduced in women with pre-eclampsia (1.95±0.9 ml·min-1·100 ml-1) compared with normal pregnant (3.9±1.4 ml·min-1·100 ml-1) and non-pregnant (3.8±1.0 ml·min-1·100 ml-1) women (P = 0.0004 and P = 0.0005 respectively; ANOVA). Blood flow in pre-eclampsia was also correlated significantly with platelet count as an index of disease severity. In addition, there was a significant negative correlation between blood flow and systolic blood pressure (r = -0.69, P = 0.004) in the women with pre-eclampsia. These findings support the hypothesis that nutritional blood flow is reduced in pre-eclampsia. We suggest that measurement of resting calf blood flow could give a non-invasive index of deterioration of nutritive blood flow to vital organs in pre-eclampsia.
Improved neoangiogenesis in transmyocardial laser revascularization combined with angiogenic adjunct in a pig model
Authors: MUELLER Xavier M. , TEVAEARAI Hendrik T. , GENTON Claude-Yves , CHAUBERT Pascal , SEGESSER Ludwig K. von 
Published: August 2015

Recent research has revealed neoangiogenesis as a basic phenomenon in transmyocardial laser revascularization (TMLR). Theoretically, myocardial neoangiogenesis could be further enhanced by the addition of angiogenic growth factors. Triads of TMLR channels were created in the lateral wall of the left ventricles of 12 pigs (mean body weight 73±5 kg), using a holmium:yttrium—aluminium garnet (YAG) laser. The animals were allocated randomly either to receive an injection of 100 µg of a bovine bone-derived growth factor mixture within the triads (n = 6), or to a control group (n = 6). Animals were killed 1 month later. Capillary and arteriolar densities were determined by computed morphometric analysis of histological sections of the triads. The capillary density of myocardial areas within the triads was significantly greater in the group receiving the bovine bone-derived growth factor mixture than in the control group (14.3±3.5/mm2 and 5.7±1.4/mm2 respectively; P < 0.001). The difference was also significant when considering arteriolar density (0.7±0.4/mm2 and 0.2±0.1/mm2 respectively; P < 0.001). For comparison, capillary and arteriolar densities of the TMLR channel scars were 48.7±9.7 and 1.9±0.5/mm2 respectively in the angiogenic group, and 46.3±13.7 and 2.3±1.3/mm2 respectively in the control group (no significant differences). These results demonstrate that the addition of angiogenic factors to TMLR stimulates neoangiogenesis significantly in the areas adjacent to the channels, but not within the channel scars. The latter are themselves strongly vascularized. Hence this combined approach, potentiating the effect of TMLR by establishing vascular connections between the neovessels of the channel scars, has the potential for improved clinical outcome.