Showing papers in "Clinical Science in 2003"

The inflammatory macrophage: a story of Jekyll and Hyde.

Abstract: Recent investigations have highlighted new roles for the macrophage (Mphi) in the biology of inflammation. Selective depletion of Mphis from inflamed sites has confirmed their predominant role in immune-mediated damage. The components of this injury have been dissected. Mphis mediate death of stromal, parenchymal and other immune cells by engaging the death programme, resulting in apoptosis. In addition, Mphis induce destruction of matrix and extracellular structures both directly and indirectly by inducing stromal cells to release matrix metalloproteinases. However, there is another side to the inflammatory Mphi. Evidence is provided that Mphis at the same sites possess the ability to aid cell proliferation, secrete and stabilize new matrix components and induce resident cells to secrete matrix components themselves. Mphi phagocytosis of apoptotic cells brings about a change from the cell-killing matrix-degrading cell to the matrix-generating cell-proliferating tissue-healing cell. Just as both Mphi types are necessary at the inflamed site, the right balance of these two populations is required for healing and resolution. Evidence of excessive inflammation as a manifestation of impaired phagocytosis of apoptotic cells emphasizes that defects in the transition from one Mphi type to another may account for the uncontrolled excessive inflammation seen in disease. Recent insights into the mechanisms by which apoptotic cells signal the change of function to the Mphi offer the prospect of novel targets for manipulation of Mphis in the inflamed tissue.

T wave peak-to-end interval and QT dispersion in acquired long QT syndrome: a new index for arrhythmogenicity.

Abstract: QT dispersion (QTD) on 12-lead ECGs has been proposed as a marker of malignant ventricular tachyarrhythmias, and increased QTD has been reported in long QT syndrome (LQTS). On the other hand, it has been demonstrated that transmural dispersion is associated with ventricular tachyarrhythmias in an experimental model. However, the precise type of QTD or transmural dispersion that contributes most to ventricular tachyarrhythmias in patients with LQTS remains unclear. We evaluated 27 patients with acquired LQTS. These patients were divided into two groups: group A (n =12), patients with polymorphic ventricular tachycardia [torsades de pointes (TdP)], and group B (n =15), patients without TdP. The QT intervals were corrected using Bazett's formula. QTD was measured as the difference between the maximum and the minimum QT intervals, and T wave peak-to-end interval divided by the QT interval (Tpe) in the V5 lead was measured as a new index. Both the corrected QTD (QTDc) and Tpe were significantly larger in group A than in group B. Logistic regression analysis revealed that a reliable predictor for TdP in the QT variables in these patients was not QTDc but Tpe. Cumulative frequency distributions revealed that a Tpe of 0.28 is a good cut-off point for TdP. Tpe did not correlate with the corrected maximum QT interval, whereas the QTDc did correlate with this parameter. In conclusion, Tpe may be the best predictor for TdP in patients with acquired LQTS.

(Ab)normal saline and physiological Hartmann's solution: a randomized double-blind crossover study.

Abstract: In this double-blind crossover study, the effects of bolus infusions of 0.9% saline (NaCl) and Hartmann's solution on serum albumin, haematocrit and serum and urinary biochemistry were compared in healthy subjects. Nine young adult male volunteers received 2-litre intravenous infusions of 0.9% saline and Hartmann's solution on separate occasions, in random order, each over 1 h. Body weight, haematocrit and serum biochemistry were measured pre-infusion and at 1 h intervals for 6 h. Biochemical analysis was performed on pooled post-infusion urine. Blood and plasma volume expansion, estimated by dilutional effects on haematocrit and serum albumin, were greater and more sustained after saline than after Hartmann's solution (P 105 mmol/l), which was sustained for >6 h, while serum chloride concentrations remained normal after Hartmann's (P <0.001 for difference between infusions). Serum bicarbonate concentration was significantly lower after saline than after Hartmann's (P =0.008). Thus excretion of both water and sodium is slower after a 2-litre intravenous bolus of 0.9% saline than after Hartmann's solution, due possibly to the more physiological [Na(+)]/[Cl(-)] ratio in Hartmann's solution (1.18:1) than in saline (1:1) and to the hyperchloraemia caused by saline.

Testosterone suppression in men with prostate cancer leads to an increase in arterial stiffness and hyperinsulinaemia

Abstract: The role of androgens in cardiovascular disease is uncertain. We aimed to determine the vascular effects of androgen suppression in men with prostate cancer. Arterial stiffness (or 'compliance') was measured in 16 men (71+/-9 years, mean+/-S.D.) prior to, and 3 months after, complete androgen suppression with gonadotrophin-releasing hormone analogues as treatment for prostate cancer. Fifteen control men (70+/-7 years) also had arterial stiffness studies at baseline and 3 months later. Two measures of arterial stiffness were employed: systemic arterial compliance (SAC) was measured by simultaneous recording of aortic flow and carotid artery pressure ('area method'), and pulse wave velocities (PWVs) were recorded with the 'Complior' system. The 16 cases underwent glucose-tolerance and fasting-lipids tests on both visits. After 3 months of testosterone suppression, there was a significant fall in SAC, which was not seen in the controls [mean change+/-S.E.M., -0.26+/-0.09 a.c.u. (arbitrary compliance unit) in the cases versus +0.06+/-0.11 in the controls; P =0.03). Central, but not peripheral, PWVs tended to increase in the cases (mean change+/-S.E.M. for aorto-femoral PWV, +0.5+/-0.4 m/s for cases versus -0.3+/-0.3 m/s for controls; P =0.08). After testosterone suppression, fasting insulin levels increased from 6.89+/-4.84 m-units/l to 11.34+/-8.16 m-units/l (mean+/-S.D.), total cholesterol increased from 5.32+/-0.77 mmol/l to 5.71+/-0.82 mmol/l and high-density lipoprotein cholesterol increased from 1.05+/-0.24 mmol/l to 1.26+/-0.36 mmol/l; P <0.005 for all. No significant change occurred in body-mass index, serum glucose, low-density lipoprotein cholesterol or triacylglycerol (triglyceride) levels. Our results indicate that loss of androgens in men leads to an increase in aortic stiffness and serum insulin levels, and may therefore adversely affect cardiovascular risk.

Periodontal disease is associated with lower antioxidant capacity in whole saliva and evidence of increased protein oxidation.

Abstract: The aim of this cohort study was to determine whether periodontitis and gingivitis are associated with impaired salivary antioxidant status and increased oxidative injury. One hundred and twenty-nine patients attending a routine dental check-up were recruited for the study. Periodontal disease status was characterized using the Community Periodontal Index of Treatment Needs (CPITN) system. Total salivary antioxidant capacity and salivary ascorbate, urate and albumin were determined in a sample of whole unstimulated saliva. Protein carbonyl concentrations were determined as an index of oxidative injury. Patients in the lowest tertile of CPITN score exhibited decreased salivary delivery of antioxidants and specifically urate than patients in the upper tertile. Poor periodontal health was associated with increased concentrations of protein carbonyls in saliva. Women had significantly lower total antioxidant status than men, regardless of periodontal health. Periodontal disease is associated with reduced salivary antioxidant status and increased oxidative damage within the oral cavity.

Uric acid reduces exercise-induced oxidative stress in healthy adults

Abstract: Uric acid (UA) possesses free-radical-scavenging properties, and systemic administration is known to increase serum antioxidant capacity. However, it is not known whether this protects against oxidative stress. The effects of raising UA concentration were studied during acute aerobic physical exercise in healthy subjects, as a model of oxidative stress characterized by increased circulating 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) concentrations. Twenty healthy subjects were recruited to a randomized double-blind placebo-controlled crossover study, and underwent systemic administration of 0.5 g of UA in 250 ml of 0.1% lithium carbonate/4% dextrose vehicle or vehicle alone as control. Subjects performed high-intensity aerobic exercise for 20 min to induce oxidative stress. Plasma 8-iso-PGF2alpha concentrations were determined at baseline, after exercise and after recovery for 20 min. A single bout of high-intensity exercise caused a significant increase in plasma 8-iso-PGF2alpha concentrations from 35.0 +/- 4.7 pg/ml to 45.6 +/- 6.7 pg/ml (P<0.01). UA administration raised serum urate concentration from 293 +/- 16 to 487 +/- 16 micromol/l (P<0.001), accompanied by increased serum antioxidant capacity from 1786+/-39 to 1899 +/- 45 micromol/l (P<0.01). UA administration abolished the exercise-induced elevation of plasma 8-iso-PGF2alpha concentrations. High UA concentrations are associated with increased serum antioxidant capacity and reduced oxidative stress during acute physical exercise in healthy subjects. These findings indicate that the antioxidant properties of UA are of biological importance in vivo.

Subclinical left ventricular dysfunction in asymptomatic patients with Type II diabetes mellitus, related to serum lipids and glycated haemoglobin.

Abstract: The aim of the present study was to measure regional ventricular function at rest and during stress in order to assess if patients with Type II diabetes have subclinical myocardial dysfunction and if it is related to risk factors. Seventy subjects (35 patients with Type II diabetes with no symptoms, signs or history of heart disease, and 35 age- and sex-matched healthy controls) had echocardiography at rest and during dobutamine stress. Myocardial velocities were measured off-line from digital loops of colour tissue Doppler. Subendocardial function was assessed from the mean longitudinal velocities of four basal segments (apical views) and radial function from the velocities of the basal posterior wall (parasternal view). Systolic functional reserve was calculated as the increase in velocity from baseline. Longitudinal peak systolic velocity was lower in patients with diabetes, at rest (5.6 +/- 1.4 compared with 6.5 +/- 1.1 cm/s) and at peak stress (10.9 +/- 2.8 compared with 14.3 +/- 2.1 cm/s) (both P <0.01). Functional reserve was impaired in patients with diabetes (+5.4 +/- 2.0 compared with +7.7 +/- 1.7 cm/s; P <0.01). Radial systolic velocity was higher in patients with diabetes (5.4 +/- 1.3 compared with 4.7 +/- 1.4 cm/s; P <0.05). Resting longitudinal systolic function correlated inversely with low-density lipoprotein-cholesterol ( r =-0.53), glycated haemoglobin ( r =-0.48), age ( r =-0.41) and diastolic blood pressure ( r =-0.38) (all P < 0.05). Peak stress systolic velocity correlated inversely with glycated haemoglobin ( r =-0.46) and age ( r =-0.44) (both P < 0.01). In conclusion, patients with Type II diabetes and no clinical heart disease have impaired subendocardial function of the left ventricle at rest and peak stress, which is related to glycated haemoglobin and serum low-density lipoprotein-cholesterol.

Beyond lysis: how complement influences cell fate

Abstract: Complement is a central component of the innate immune system involved in protection against pathogens. For many years, complement has been known to cause death of targets, either indirectly by attracting and activating phagocytes or directly by formation of a membrane pore, the membrane attack complex. More recently, it has been recognized that complement may cause other 'non-classical' effects that may not directly be aimed at killing of pathogens. Products of complement activation collaborate with the adaptive immune system to enhance responses to antigens. The membrane attack complex of complement, apart from lysing cells, can also trigger diverse events in target cells that include cell activation, proliferation, resistance to subsequent complement attack and either resistance to, or induction of, apoptosis. Various complement products play important roles in signalling for clearance by phagocytes of apoptotic self cells. Here we review some of these non-classical activities of complement and stress the roles that they may play in maintaining the integrity of the organism.

Increased plasma urotensin II levels in patients with diabetes mellitus

Abstract: Urotensin II (UII) is the most potent vasoconstrictor peptide, whereas it acts as a vasodilator on some arteries. We studied plasma levels of UII in diabetic patients with normal serum creatinine levels (<90 micromol/l) and the expression of UII and its receptor in cultured human vascular endothelial cells. Plasma UII levels were significantly elevated by 1.8-fold in diabetic patients without proteinuria (7.8+/-0.6 fmol/ml; P <0.0001) and 1.7-fold in those with overt proteinuria (7.3+/-0.9 fmol/ml; P =0.0018) when compared with healthy subjects (4.4+/-0.2 fmol/ml). No significant correlation was obtained between plasma UII levels and fasting blood sugar (P =0.631 and P =0.853 in non-proteinuric and proteinuric diabetic patients respectively), glycated haemoglobin levels (P =0.376 and P =0.888 respectively) or serum creatinine levels (P =0.301 and P =0.568 respectively). Reverse transcriptase-PCR analysis showed the expression of mRNAs encoding UII precursor and UII-receptor precursors in cultured human coronary artery endothelial cells and umbilical vein endothelial cells, suggesting that vascular endothelial cells are one of the sources of UII in blood. These findings suggest that elevation of plasma UII levels may be an important background factor in diabetic cardiovascular and organ complications in diabetic subjects without renal failure.

Glutamine attenuates post-traumatic glutathione depletion in human muscle

Abstract: Glutathione is quantitatively the most important endogenous scavenger system. Glutathione depletion in skeletal muscle is pronounced following major trauma and sepsis in intensive care unit patients. Also, following elective surgery, glutathione depletion occurs in parallel with a progressive decline in muscle glutamine concentration. The present study was designed to test the hypothesis that glutamine supplementation may counteract glutathione depletion in a human trauma model. A homogeneous group of patients (n = 17) undergoing a standardized surgical procedure were prospectively randomly allocated to receive glutamine (0.56 g x day(-1) x kg(-1)) or placebo as part of isonitrogenous and isocaloric nutrition. Percutaneous muscle biopsies and blood samples were taken pre-operatively and at 24 and 72 h after surgery. The concentrations of muscle glutathione and related amino acids were determined in muscle tissue and plasma. In the control (unsupplemented) subjects, total muscle glutathione had decreased by 47+/-8% and 37+/-11% and reduced glutathione had decreased by 53+/-10% and 45+/-16% respectively at 24 and 72 h after surgery (P < 0.05). In contrast, in the glutamine-supplemented group, no significant post-operative decreases in total or reduced glutathione were seen following surgery. Muscle free glutamine had decreased at 72 h after surgery in both groups, by 41.4+/-14.8% (P < 0.05) in the glutamine-supplemented group and by 46.0+/-14.3% (P < 0.05) in the control group. In conclusion, the present study demonstrates that intravenous glutamine supplementation attenuates glutathione depletion in skeletal muscle in humans following standardized surgical trauma.

Renal function and angiotensin AT1 receptor expression in young rats following intrauterine exposure to a maternal low-protein diet.

Abstract: Recent studies have proposed a link between impaired nephrogenesis, decreased activity of the renin-angiotensin system and the onset of hypertension in rats exposed in the uterus to a maternal low-protein diet. However, there is no detailed information about renal function in this model; hence the aim of the present study was to assess renal function in young (4-week-old) rats exposed in the uterus to a maternal low-protein diet. Pregnant Wistar rats were fed isocalorific diets containing either 18% (normal protein; offspring denoted NP rats) or 9% (low protein; offspring denoted LP rats) (w/w) protein from conception until birth. At 4 weeks of age, male offspring were anaesthetized and prepared for the study of renal function, during which animals received saline alone, a bolus of enalapril (5 mg.kg(-1)) or a bolus of enalapril followed by an infusion of angiotensin II (30 ng.min(-1).kg(-1)). Under control conditions, renal haemodynamic and tubular function did not differ. However, when challenged with angiotensin II, LP rats responded with a greater decrease in glomerular filtration rate than did NP rats [NP, 2.0+/-0.2 ml.min(-1).g(-1) kidney weight ( n =9); LP, 1.0+/-0.2 ml.min(-1).g(-1) kidney weight ( n =5); P <0.05]. Renal electrolyte excretion did not differ. LP rats had significantly fewer glomeruli than NP rats ( P <0.01). Renal angiotensin II AT(1) receptor expression was increased ( P <0.01) by 24% in LP rats. It is concluded that blood pressure may be elevated in LP rats in order to maintain glomerular filtration rate against a background of fewer nephrons. Increased AT(1) receptor expression, which may arise as a result of the direct effect of protein restriction or in response to the reported decrease in renal tissue angiotensin II concentration, could also contribute to the elevated blood pressure of this model.

Cigarette smoking is associated with an acute impairment of microvascular function in humans

Abstract: An effect on microvascular function has been proposed as a possible mechanism explaining the association of acute smoking with increased blood pressure and decreased insulin sensitivity. However, the effects of smoking on microvascular function have not been studied. We have investigated the acute effects of smoking on microvascular function in 12 healthy smokers. Before and after smoking a cigarette, we measured heart rate, blood pressure and capillary recruitment during peak reactive hyperaemia. We also measured endothelium-dependent and endothelium-independent vasodilatation of the skin microcirculation with iontophoresis of acetylcholine and sodium nitroprusside respectively combined with laser Doppler fluxmetry. To exclude non-specific changes, a control study with sham smoking was performed. The smoking and sham smoking studies were conducted in a randomized order. Compared with sham smoking, acute smoking caused increases in heart rate (smoking, 9.3+/-4.1 beats/min; sham, -1.3+/-3.0 beats/min; P < 0.001) and systolic blood pressure (smoking, 6.3+/-8.8 mmHg; sham, 0.8+/-4.4 mmHg; P < 0.05); decreases in absolute (smoking, -4.9+/-6.9 per mm(2); sham, 0.8+/-2.1 per mm(2); P = 0.01) and relative (smoking, -13.8+/-21.4%; sham, 1.9+/-6.9%; P = 0.02) capillary recruitment during peak reactive hyperaemia; and decreases in absolute [smoking, -62.4+/-47.7 perfusion units (PU); sham, -30.8+/-32.6 PU; P = 0.04] and relative (smoking, -147+/-163%; sham, 32+/-225%; P = 0.07) vasodilatation caused by acetylcholine. Absolute (smoking, -31.6+/-58.5 PU; sham, -8.4+/-44.0 PU; P = 0.3) and relative (smoking, -50.2+/-219.0%; sham, -17.1+/-139%; P = 0.7) vasodilatation caused by sodium nitroprusside were not affected. Thus acute smoking is associated with impaired capillary recruitment during peak reactive hyperaemia and impaired microvascular endothelium-dependent vasodilatation. These findings may explain the increased blood pressure and decreased insulin sensitivity that have been observed after acute smoking.

Statins and their role in vascular protection.

Abstract: The statins reduce cholesterol synthesis through inhibition of HMG-CoA (3-hydroxy-3-methylglutaryl-CoA) reductase and are widely prescribed for hyperlipidaemia to reduce the risk of atherosclerotic complications. The beneficial effect of lipid lowering by statins in the treatment of coronary heart disease has been demonstrated in large clinical trials. However, statins appear to have additional benefits on vascular function above and beyond their lipid lowering effects. Through inhibition of L-mevalonate synthesis, statins also prevent the synthesis of isoprenoid intermediates, including farnesylpyrophosphate and geranylgeranylpyrophosphate. Isoprenylation is important in the post-translational modification of a variety of proteins, including the small GTPases Rho, Rac and Ras, and hence plays an integral role in cellular signalling. Moreover, interference with isoprenylation underlies many of the beneficial actions of the statins on vascular endothelium, which include increased endothelial nitric oxide synthase expression, pro-angiogenic effects, increased fibrinolytic activity, immunomodulatory and anti-inflammatory actions, including increased resistance to complement. This has led to interest in the use of this class of drugs outside the realm of cardiovascular disease.

Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans.

Abstract: Most research on creatine has focused on short-term creatine loading and its effect on high-intensity performance capacity. Some studies have investigated the effect of prolonged creatine use during strength training. However, studies on the effects of prolonged creatine supplementation are lacking. In the present study, we have assessed the effects of both creatine loading and prolonged supplementation on muscle creatine content, body composition, muscle and whole-body oxidative capacity, substrate utilization during submaximal exercise, and on repeated supramaximal sprint, as well as endurance-type time-trial performance on a cycle ergometer. Twenty subjects ingested creatine or a placebo during a 5-day loading period (20g·day -1 ) after which supplementation was continued for up to 6 weeks (2g·day -1 ). Creatine loading increased muscle free creatine, creatine phosphate (CrP) and total creatine content ( P -1 maintenance dose, as suggested by an American College of Sports Medicine Roundtable, resulted in a decline in both the elevated CrP and total creatine content and maintenance of the free creatine concentration. Both short- and long-term creatine supplementation improved performance during repeated supramaximal sprints on a cycle ergometer. However, whole-body and muscle oxidative capacity, substrate utilization and time-trial performance were not affected. The increase in body mass following creatine loading was maintained after 6 weeks of continued supplementation and accounted for by a corresponding increase in fat-free mass. This study provides definite evidence that prolonged creatine supplementation in humans does not increase muscle or whole-body oxidative capacity and, as such, does not influence substrate utilization or performance during endurance cycling exercise. In addition, our findings suggest that prolonged creatine ingestion induces an increase in fat-free mass.

Cardiovascular and hormonal effects of subcutaneous administration of ghrelin, a novel growth hormone-releasing peptide, in healthy humans

Abstract: Ghrelin is a novel GH (growth hormone)-releasing peptide isolated from the stomach. The cardiovascular and hormonal effects of the subcutaneous administration of ghrelin in humans remain unknown. Six healthy volunteers each received subcutaneous administration of three doses of ghrelin (1, 5 or 10 microg/kg) and placebo; the order of administration was randomized, and separate doses were given at least 24 h apart. The serum GH level dose-dependently increased from 0.5 +/- 0.4 to 3.6 +/- 2.1 ng/ml (1 microg/kg ghrelin; P=0.99 compared with baseline), 27.1 +/- 12.0 ng/ml (5 microg/kg; P<0.01 compared with baseline) and 45.4 +/- 12.8 ng/ml (10 microg/kg; P<0.01 compared with baseline) 30 min after ghrelin administration. Subcutaneous administration of ghrelin did not significantly alter circulating levels of corticotropin, cortisol, insulin-like growth factor-1, noradrenaline or adrenaline, although 10 microg/kg ghrelin slightly increased the prolactin level. No significant changes in heart rate or mean arterial pressure were observed. In contrast, the left ventricular ejection fraction, as assessed by echocardiography, increased dose-dependently from 63.5 +/- 0.6% to 65.1 +/- 0.9% (1 microg/kg ghrelin; P=0.97 compared with baseline), 69.6 +/- 1.3% (5 microg/kg; P<0.01 compared with baseline) and 71.5 +/- 0.9% (10 microg/kg; P<0.01 compared with baseline) 30 min after ghrelin administration. These haemodynamic and hormonal changes were still apparent 60 min after ghrelin injection. In conclusion, subcutaneous administration of ghrelin dose-dependently induced relatively specific GH release and enhanced cardiac performance in humans.

Response of glucose disposal to hyperinsulinaemia in human hypothyroidism and hyperthyroidism.

Abstract: We have examined insulin action on glucose metabolism in six hypothyroid patients before and after regular thyroid hormone treatment, and in six healthy volunteers before and after transient induction of moderate hyperthyroidism. Insulin was infused under euglycaemic and eukalaemic clamps. An appropriate amino acid infusion was used to blunt insulin-induced decreases in amino acid levels. Glucose kinetics were assessed using a primed continuous infusion of [6,6-(2)H(2)]glucose. The results showed that basal plasma insulin and glucose levels (i.e. before infusion) were similar in each case. Despite similar insulin infusion rates, the plateau value of insulin was lower after thyroid treatment in both hypothyroid patients and healthy volunteers. The rate of exogenous glucose needed to maintain plasma glucose at a steady-state level was increased by thyroid hormone in hypothyroid patients (P <0.05), but not in healthy volunteers. Thyroid treatment resulted in a significant increase in basal glucose disposal in both groups (P <0.05). Insulin, in conjunction with glucose and amino acids, significantly stimulated glucose disposal (P <0.05) under all conditions. The incremental increase in glucose disposal after infusion tended to be higher following thyroid hormone treatment, but this was not statistically significant. However, the ratio of the incremental increase in glucose disposal to the increase in plasma insulin was significantly improved after thyroid hormone treatment in hypothyroid patients (P <0.05). It was also increased in healthy volunteers, but not significantly. We conclude that thyroid hormones improve the ability of insulin to stimulate glucose disposal related to insulinaemia. This phenomenon may be highly sensitive, because it was only apparent at low thyroid hormone levels.

Decreased left ventricular longitudinal contraction in normotensive and normoalbuminuric patients with Type II diabetes mellitus: a Doppler tissue tracking and strain rate echocardiography study.

Abstract: Type II diabetes mellitus is associated with congestive heart failure with preserved ejection fraction. This group of patients has been assumed to have isolated diastolic dysfunction; however, the longitudinal systolic contraction of the left ventricle has not been studied previously. The objective of the present study was to investigate the longitudinal contraction of the left ventricle in normotensive Type II diabetes mellitus patients with normal ejection fraction. We examined 32 normotensive patients with Type II diabetes mellitus with ejection fraction >0.55 and fractional shortening >0.25. Exclusion criteria were angina pectoris, cardiac valve disease, albuminuria, retinopathy or neuropathy. Normal subjects (n =32) served as controls. A 16 segment model of motion amplitude assessed left ventricular longitudinal contraction and the average of the segments was calculated as the tissue tracking score index. Peak systolic velocity and strain rate was also obtained in each segment. Patients with Type II diabetes mellitus had a significantly lower tissue tracking score index compared with normal subjects (5.8+/-1.6 mm compared with 7.7+/-1.1 mm; P <0.001). Mean peak systolic velocity was also significantly lower (4.3+/-1.5 cm/s compared with 5.4+/-1.0 cm/s; P <0.001), as well as peak systolic strain rate (-1.2+/-0.3 s(-1) compared with -1.6+/-0.4 s(-1); P <0.001). Patients with Type II diabetes mellitus and preserved diastolic function had a significantly lower tissue tracking score index compared with normal subjects (6.6+/-1.5 mm; P <0.001), but patients with diastolic dysfunction had an even more profound decrease in tissue tracking score index compared with patients without diastolic dysfunction (4.9+/-0.9 mm; P <0.01). In conclusion, the longitudinal systolic contraction was significantly decreased in normotensive patients with Type II diabetes mellitus with normal ejection fraction, which was most profound in patients with concomitant diastolic dysfunction.

Estimation of central aortic pressure by SphygmoCor requires intra-arterial peripheral pressures.

Abstract: Central arterial pressure, measured close to the heart, may be of more patho-physiological importance than conventional non-invasive cuff blood pressure. The technique of applanation tonometry using SphygmoCor® has been proposed as a non-invasive method of estimating central pressure. This relies on mathematically derived generalized transfer functions, which have been previously validated using invasive peripheral pressure measurements. We compared simultaneous estimates of central aortic pressure using this technique with those measured directly during the routine diagnostic cardiac catheterization of 30 subjects (age range 27–84 years), half of whom were aged 65 years or more. This was done by applanating the left radial artery and recording the non-invasive brachial cuff blood pressure to generate a central aortic pressure estimate, using the SphygmoCor® radial transfer function. The comparative results were analysed using Bland—Altman plots of mean difference. SphygmoCor®, on average, underestimated systolic central arterial pressure by 13.3 mmHg and overestimated diastolic pressure by 11.5 mmHg. The results were similar in patients aged under and above 65 years. Furthermore, non-invasively measured brachial pressures were seen to give an overall closer estimate of the central arterial pressure than the SphygmoCor® system. The transfer function has been validated from invasively measured arterial pressures and the current use by the system of non-invasive measures may explain the discrepancies. However, age, drugs and arterial disease would also be expected to play a role.

Regulation of hypoxia-inducible factor-1α by cyclical mechanical stretch in rat vascular smooth muscle cells

Abstract: Vascular smooth muscle cells (VSMCs) are exposed to hormonal and mechanical stress in vivo. Hormonal factors have been shown to affect hypoxia-inducible factor-1alpha (HIF-1alpha). How mechanical stress affects the regulation of HIF-1alpha in VSMCs has not been reported previously, and therefore we sought to investigate the regulation of HIF-1alpha by cyclical mechanical stretch in cultured rat VSMCs. Rat VSMCs grown on a flexible membrane base were stretched by vacuum to 20% of the maximum elongation at 60 cycles/min. The levels of HIF-1alpha protein began to increase as early as 2 h after stretch was applied and reached a maximum of 2.8-fold over the control by 4 h. Real-time PCR showed that the levels of HIF-1alpha mRNA increased 2.1-fold after cyclical stretch for 4 h. Cyclical mechanical stretch also increased the immunohistochemical labelling of HIF-1alpha in VSMCs after cyclical stretch for 4 h. The phosphorylation of p42/p44 mitogen-activated protein kinase (MAP kinase) increased after stretch and this was inhibited by the MAP kinase kinase inhibitors PD98059 and U0126. PD98059 and U0126 also blocked HIF-1alpha gene expression induced by cyclical stretch. In conclusion, cyclical mechanical stretch activates the gene expression of HIF-1alpha in cultured VSMCs and this mechanical effect is possibly mediated by the p42/p44 MAP kinase kinase pathway.

Fetuin/α2-HS glycoprotein enhances phagocytosis of apoptotic cells and macropinocytosis by human macrophages

Abstract: Inflammatory diseases are associated with reduced serum concentrations of α2-HS glycoprotein (the human homologue of bovine fetuin), but the role of fetuin in inflammation is poorly understood. We hypothesized that fetuin may influence the resolution of inflammation by modulating the phagocytosis of apoptotic cells by macrophages. Using an in vitro flow cytometry-based phagocytosis assay, we investigated the role of fetuin in apoptotic cell clearance. Bovine fetuin and human α2-HS glycoprotein significantly augmented the phagocytosis of apoptotic cells by human peripheral blood monocyte-derived macrophages, whereas the control proteins BSA, sialylated BSA and asialofetuin were ineffective. The enhancement of phagocytosis was concentration-dependent, and required the presence of intact fetuin at the time of interaction between macrophages and apoptotic cells. Fetuin also substantially increased the uptake of labelled dextran 70000 by macrophages, which occurs by macropinocytosis, suggesting that this may be one of the mechanisms utilized for apoptotic cell uptake.

Decrease of serum levels of the anti-inflammatory cytokine interleukin-10 in patients with advanced chronic heart failure.

Abstract: Inflammation plays a significant contributory role in the pathogenesis of chronic heart failure (CHF). Many studies have shown enhanced plasma levels of proinflammatory cytokines [i.e. tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6] in patients with CHF. However, there are only few reports on the regulation of anti-inflammatory cytokines such as IL-10. IL-10 has potent deactivating properties in macrophages and T-cells and thus acts as a down-regulator of cell-mediated immune responses. The aim of the present study was to assess whether serum concentrations of IL-10 significantly differ between patients with CHF and healthy control subjects. Patients with CHF [ n =50; 66.9+/-12.6 years; mean ejection fraction, 22.1+/-9.2%; New York Heart Association (NYHA) class II-IV] and 25 healthy controls (63.6+/-10.2 years) were examined. Of the 50 patients with CHF, 32 patients were taking aspirin (100 mg/day) and 33 patients had lipid-lowering therapy with a statin. Serum IL-10 as well as TNF-alpha concentrations were measured using commercially available immunoassays. Patients with CHF showed significantly lower IL-10 concentrations (2.3+/-1.9 compared with 5.2+/-2.3 pg/ml; P <0.001). Patients with advanced CHF (NYHA class III and IV) had the lowest IL-10 plasma levels. Aspirin and statin therapy did not significantly influence serum levels of IL-10. The ratio of TNF-alpha to IL-10 was significantly higher in patients with advanced CHF (NYHA class III and IV, ratio 3.2+/-1.2 and 3.1+/-1.1 respectively, compared with control 0.4+/-0.2; P <0.01). Our present study demonstrates significantly decreased serum levels of IL-10 in patients with advanced CHF. Since IL-10 is known as a potent anti-inflammatory cytokine, its decrease in advanced CHF may favour the inflammatory milieu in CHF.

DC-SIGN (dendritic cell-specific ICAM-grabbing non-integrin) and DC-SIGN-related (DC-SIGNR): friend or foe?

Abstract: C-type lectins are calcium-dependent carbohydrate-binding proteins with a wide range of biological functions, many of which are related to immunity. DC-SIGN (dendritic cell-specific ICAM-grabbing non-integrin, where ICAM is intercellular adhesion molecule) is a recently described mannose-specific C-type lectin expressed by dendritic cells. Dendritic cells are potent antigen-presenting cells capable of activating T-lymphocytes. DC-SIGN, which is expressed by dendritic cells, binds to ICAM-3 on T-lymphocytes, therefore playing an important role in the activation of T-lymphocytes. DC-SIGN can also bind HIV, and the virus may remain bound to DC-SIGN for protracted periods. DC-SIGN may deliver bound HIV to permissive cell types, mediating infection with high efficiency. A closely related C-type lectin, DC-SIGN-related molecule (DC-SIGNR) has also been described. DC-SIGNR is expressed by restricted subsets of endothelial cells, but has similar ICAM-3 and HIV-binding properties to DC-SIGN. This review describes the mapping of DC-SIGN and DC-SIGNR to chromosome 19p13.3 adjacent to the previously described C-type lectin, CD23 [the low-affinity receptor for immunoglobulin E (FcERII)]. The similar genomic organization of these three genes is discussed and consideration is given to the evolutionary duplications that may underlie this arrangement. Both DC-SIGN and DC-SIGNR possess a neck region, made up of multiple repeats, which supports the ligand-binding domain. Consideration is given to the biological reasons underlying the considerable polymorphism in the numbers of repeats in DC-SIGNR, but not DC-SIGN. The expression patterns of both DC-SIGN and DC-SIGNR are discussed in detail, with particular attention to the expression of both molecules in the placenta, which may have implications for the vertical transmission of HIV. Since dendritic cells may be important in determining the phenotype of many immune responses, via effects on T-lymphocytes, the differential expression of DC-SIGN by particular dendritic cell subsets may have important implications for the immunobiological functions of DC-SIGN. Similarly, the expression of DC-SIGNR by very restricted subsets of endothelial cells may give clues to the function of DC-SIGNR. Finally, the role of DC-SIGN in pathology, particularly in infective and neoplastic processes, is discussed, followed by speculation about likely future developments in this field.

Functional implications of genetic variation in non-coding DNA for disease susceptibility and gene regulation

Abstract: The role of host genetic variation in determining susceptibility to complex disease traits is the subject of much research effort, but it often remains unclear whether disease-associated genetic polymorphisms are themselves functionally relevant or acting only as markers within an extended haplotype. Experimental approaches to investigate the functional impact of polymorphisms in non-coding regulatory DNA sequences for gene expression are discussed, including the role of gel-shift assays, DNA footprinting and reporter gene analysis. The limitations of different experimental approaches are presented together with future prospects for in vivo analysis. The strategic application of these functional approaches is discussed and illustrated by analysis of the role of genetic variation in the tumour necrosis factor promoter region in determining susceptibility to severe malaria.

Bioactive natural compounds for the treatment of gastrointestinal disorders.

Abstract: Many healthy subjects and patients are taking natural bioactive products for the prevention and treatment of multiple conditions, including gastrointestinal disorders. Based on current evidence, the scientific validity of the use of many of these commercial compounds by the general public is severely limited, with quality control and regulatory issues continuing to be a concern. Nevertheless, there is sufficient preliminary data to warrant further research of these products in order to identify novel compounds for potential clinical use in addition to performing formal randomized controlled clinical trials of the commercial preparations.

Greater than predicted decrease in energy expenditure during exercise after body weight loss in obese men.

Abstract: This study was performed retrospectively to investigate whether exercise energy expenditure (EE) measured during a standardized treadmill protocol (4.5 km/h at 0% grade) falls below predicted values after body weight loss in obese men. A reference equation was established to predict net exercise EE in a control sample of 83 obese individuals (27 kg/m(2)< or = body mass index <45 kg/m(2)), using age, fat mass and fat-free mass as independent variables. This equation was then used to predict net exercise EE in another group of 11 obese men before and after a 15-week drug-based weight loss programme that was coupled with energy restriction [-2929 kJ/day (-700 kcal/day)]. Body weight and body composition were determined by hydrodensitometry. Net exercise EE, insulin, leptin, 3,3',5-tri-iodothyronine and free thyroxine were measured after an overnight fast at baseline and 2-4 weeks after the end of the programme, when subjects were weight stable. Body weight was significantly reduced (-11%; P <0.01) at the end of the weight loss programme. At baseline, measured net exercise EE was similar to that predicted from the regression equation [19.6 and 19.8 kJ/min (4.69 and 4.74 kcal/min) respectively; not significant]. However, after the end of the intervention, measured net exercise EE was significantly below the predicted value [15.5 and 17.3 kJ/min (3.71 and 4.14 kcal/min) respectively; P <0.01]. The difference between the predicted and the measured fall in net exercise EE was significantly associated with changes in leptin concentration ( r =0.79, P <0.01), even after correction for changes in fat mass and insulin. These observations suggest that net exercise EE falls below predicted values after body weight loss. In addition, this greater than predicted decrease in net exercise EE was associated with changes in leptin.

Augmented sympathetic neural response to simulated obstructive apnoea in human heart failure.

Abstract: Sleep apnoea in heart failure increases mortality risk, possibly as a result of greater activation of the sympathetic nervous system. In healthy subjects, simulated central apnoeas (holding breath) and obstructive apnoeas (Mueller manoeuvres) increase muscle sympathetic activity equally, primarily through chemoreceptor stimulation. In heart failure, however, Mueller manoeuvres cause greater reductions in blood pressure than breath holds. We hypothesized that in heart failure, the summation of arterial baroreceptor unloading and chemoreceptor stimulation would increase sympathetic activity more during obstructive than central apnoeas. Healthy human subjects and heart failure patients (seven of each) performed 15-s breath holds and 15-s Mueller manoeuvres. Breath holds evoked a progressive increase in muscle sympathetic nerve activity in both groups, but had no effect on blood pressure. In healthy subjects, breath holds and Mueller manoeuvres caused equal peaks in sympathetic activity. In contrast, in heart failure patients, Mueller manoeuvres caused a progressive decrease in blood pressure (P < 0.05) and greater increases in sympathetic activity than breath holds (P < 0.01). In heart failure, simulated obstructive apnoea elicits greater increases in sympathetic activity than simulated central apnoea, due to its additional hypotensive effect. These present findings offer novel insight into the potential role of sleep apnoea in augmenting sympathetic activity and accelerating disease progression in heart failure.

Detection and analysis of urinary peptides by on-line liquid chromatography and mass spectrometry: application to patients with renal Fanconi syndrome.

Abstract: Urinary proteomics has become a topical and potentially valuable field of study in relation to normal and abnormal renal function. Filtered bioactive peptides present in high concentration in the nephron of patients with tubular proteinuria may have downstream effects on renal tubular function. In renal Fanconi syndromes, such as Dent's disease, peptides implicated in altered tubular function or injury have recently been measured in urine by immunochemical methods. However, the limited availability of antibodies means that only certain peptides can be detected in this way. We have used nanoflow liquid chromatography and tandem mass spectrometry (nanoLC-MS/MS) as a complementary technique to analyse urinary peptides. Urine was desalted by solid-phase extraction (SPE) and its peptides were then separated from neutral and acidic compounds by strong cation-exchange chromatography (SCX), which was also used to fractionate the peptide mixture. Fractions from the SCX step were separated further by reversed-phase LC and analysed on-line by MS/MS. Extraction by SPE showed a good recovery of small peptides. We detected over 100 molecular species in urine samples from three individuals with Dent's disease. In addition to plasma and known urinary proteins, we identified some novel proteins and potentially bioactive peptides in urine from these patients, which were not present in normal urine. These data show that nanoLC-MS/MS complements existing techniques for the identification of polypeptides in urine. This approach is a potentially powerful tool to discover new markers and/or causative factors in renal disease; in addition, its sensitivity may also make it applicable to the direct ultramicroanalysis of renal tubule fluid.

Aspects of organ protein, amino acid and glucose metabolism in a porcine model of hypermetabolic sepsis.

Abstract: Although glucose and protein metabolism have been investigated extensively in experimental models of hypodynamic sepsis, relatively little information is available regarding the compensated stage of sepsis. We investigated interorgan amino acid and glucose metabolism in a porcine model of compensated hyperdynamic sepsis. Fasting catheterized pigs received endotoxin ( Escherichia coli lipopolysaccharide; 3 microg.h(-1).kg(-1); intravenous) or saline (controls) and volume resuscitation over 24 h to reproduce hyperdynamic sepsis. Primed-constant infusions of p -aminohippurate and (3)H-labelled isotopes were used to measure glucose, amino acid and protein metabolism across the portal-drained viscera, liver and hindquarters (to represent muscle) at 0 and 24 h of endotoxaemia. Whole-body protein and glucose flux were increased during hyperdynamic compensated sepsis. In endotoxaemic pigs, visceral protein was conserved, and hindquarter protein breakdown exceeded the increase in liver protein synthesis, resulting in net whole-body protein loss. Endotoxaemia increased hindquarter and visceral glycolysis and branched-chain amino acid transamination. The rate of efflux of glutamine and alanine from the hindquarters was higher than anticipated from protein breakdown, indicating de novo synthesis of these amino acids during endotoxaemia. In addition to the hindquarters, the portal-drained viscera provided substantial gluconeogenic amino acids and lactate to the liver. Although increased liver glutamate release constitutes an important nitrogen-sparing mechanism and carbon skeletons are effectively being cycled in glucose, net body protein is lost through increased ureagenesis during the hyperdynamic stage of sepsis. Specific amino acid requirements may develop in compensated hyperdynamic sepsis that is characterized by maintained organ perfusion and increased substrate utilization at the expense of body protein.