The human Toll-like receptor 2 (TLR2) response during pathogenic Leptospira infection.

Background: Human innate immune responses are triggered through the interaction of human pattern recognition receptors and pathogen-associated molecular patterns. The role of toll-like receptor2 (TLR2) in mice innate immune response to leptospirosis is well established, while human studies are limited. The present study aimed to determine the TLR2 response among confirmed cases of leptospirosis. Methodology/Principle findings: The study has two components. Clinically suspected patients of leptospirosis were confirmed using a previously validated qPCR assay. Total RNA was extracted from patients' RNA-stabilized whole blood samples. Human TLR2 gene expression (RT-qPCR) analysis was carried out using an exon-exon spanning primer pair, using CFX Maestro™ software. The first set of patient samples was used to calculate the Relative Normalized Expression (ΔΔCq value) of the TLR2 gene in comparison to a healthy control sample and normalized by the reference gene GAPDH (Glyceraldehyde-3-phosphate dehydrogenase). Secondly, recruited patient samples were subjected to TLR2 gene expression analysis and compared to healthy controls and normalized by the reference genes Beta-2-microglobulin(B2M), Hypoxanthine phosphoribosyltransferase 1 (HPRT 1).In the initial cohort of 64 confirmed leptospirosis cases, 18 were selected for human TLR2 gene expression analysis based on criteria of leptospiremia and RNA yield. Within this group, one individual exhibited a down-regulation of TLR2 gene (Expression/ΔΔCq=0.01352), whereas the remaining subjects presented no significant change in gene expression. In a subsequent cohort of 23 confirmed cases, 13 were chosen for similar analysis. Among these, three patients demonstrated down-regulation of TLR2 gene expression, with Expression/ΔΔCq values of 0.86574, 0.47200, and 0.28579, respectively. No TLR2 gene expression was noted in the other patients within this second group. Conclusions: Our investigation into the acute phase of leptospirosis using human clinical samples has revealed a downregulation of TLR2 gene expression. This observation contrasts to the upregulation commonly reported in the majority of in-vitro and in-vivo studies of Leptospira infection. These preliminary findings prompt a need for further research to explore the mechanisms underlying TLR2's role in the pathogenesis of leptospirosis, which may differ in clinical settings compared to laboratory models.

Assessing beans as a source of intrinsic fiber on satiety in men and women with metabolic syndrome.

Dietary fiber is well-known for its satiety inducing properties. Adding fibers to mixed dishes is one way to increase fiber intake. However, adding fibers to foods versus including foods inherently containing fiber may reveal differing effects on satiety. The present study aimed to explore the satiety effects of adding fiber to a mixed meal versus using beans (Phaseolus vulgaris) as a source of intrinsic fiber in the meal. In this pilot study, 12 men and women with metabolic syndrome were randomly assigned to eat three standard meals in a crossover design on three different occasions that contained either no added fiber (control (NF)), extrinsic or added fiber (AF), or whole black beans as the source of intrinsic fiber (BN). Meals were matched for energy and macronutrient composition. Five hour postprandial subjective satiety was measured along with blood glucose, insulin, and the GI hormones, cholecystokinin (CCK) and peptide tyrosine tyrosine (PYY3-36). All meals induced fullness to a similar degree; however, the AF meal suppressed prospective consumption (F2,187 = 9.05, P = 0.0002) compared to the BN or NF meals. The NF meal tended to result in more satisfaction than the BN meal (F2,187 = 5.91, P = 0.003). The BN meal produced significantly higher postprandial CCK concentrations compared to the AF (F2,187 = 6.82, P = 0.001) and NF meals (F2,187 = 6.82, P = 0.002). Similar findings were observed for PYY3-36 response for BN > AF meal (F2,170 = 9.11, P < 0.0001). Postprandial insulin was significantly reduced after the BN meal, compared to the NF (F2,187 = 22.36, P < 0.0001) meal. These findings suggest that incorporating whole black beans into a meal has acute beneficial metabolic and GI hormone responses in adults with metabolic syndrome and are preferred over adding equivalent amounts of fiber from a supplement.

Black Beans, Fiber, and Antioxidant Capacity Pilot Study: Examination of Whole Foods vs. Functional Components on Postprandial Metabolic, Oxidative Stress, and Inflammation in Adults with Metabolic Syndrome.

Beans (Phaseolus vulgaris) contain bioactive components with functional properties that may modify cardiovascular risk. The aims of this pilot study were to evaluate the ability of black beans to attenuate postprandial metabolic, oxidative stress, and inflammatory responses and determine relative contribution of dietary fiber and antioxidant capacity of beans to the overall effect. In this randomized, controlled, crossover trial, 12 adults with metabolic syndrome (MetS) consumed one of three meals (black bean (BB), fiber matched (FM), and antioxidant capacity matched (AM)) on three occasions that included blood collection before (fasting) and five hours postprandially. Insulin was lower after the BB meal, compared to the FM or AM meals (p < 0.0001). A significant meal × time interaction was observed for plasma antioxidant capacity (p = 0.002) revealing differences over time: AM > BB > FM. Oxidized LDL (oxLDL) was not different by meal, although a trend for declining oxLDL was observed after the BB and AM meals at five hours compared to the FM meal. Triglycerides and interleukin-6 (IL-6) increased in response to meals (p < 0.0001). Inclusion of black beans with a typical Western-style meal attenuates postprandial insulin and moderately enhances postprandial antioxidant endpoints in adults with MetS, which could only be partly explained by fiber content and properties of antioxidant capacity.

Another look at the results of the JUPITER trial.

Justification for the Use of Statins in Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER) was a placebo-controlled trial undertaken on "apparently healthy" subjects selected primarily on the basis of high-sensitivity C-reactive protein concentrations >or=2.0 mg/L. JUPITER showed that rosuvastatin reduced the incidence of cardiac events compared to a control group. The study population (median age 66 years) included men and women with the metabolic syndrome (about 41%), median blood pressures in the prehypertensive range, current smoking (about 15%), median body mass indexes higher than normal, and Framingham 10-year risk >10% (about 50%). The presence of these risk factors indicates that a significant proportion of subjects were not "healthy" and warranted aggressive management under current guidelines, without the measurement of high-sensitivity C-reactive protein. Furthermore, <17% of the trial participants were taking guidelines-recommended aspirin, and 25% had systolic blood pressures >145 mm Hg and would have merited treatment for hypertension. It is likely that many of the participants did not receive care consistent with current standards. Thus, the benefit of statin therapy would have been more difficult to demonstrate if standard therapeutic recommendations had been followed. In conclusion, these considerations cast doubt on the contention that statin therapy should be initiated in apparently healthy individuals on the basis of elevated high-sensitivity C-reactive protein levels.

Assessment of risk for developing coronary heart disease in asymptomatic individuals.

The assessment of risk for developing coronary heart disease (CHD) in asymptomatic individuals continues to be an important challenge for clinicians. We suggest that the Framingham risk score provides a pragmatic basis for assessing global 10-year CHD risk in this population. The Framingham risk score should be supplemented with additional information pertaining to diabetes, metabolic syndrome, family history, and peripheral arterial disease before a final decision is made with respect to individual risk. In terms of additional investigations, it is suggested that measurement of the ankle brachial index and a stress test that focuses on functional capacity be incorporated into the evaluation of asymptomatic subjects for CHD. The role of emerging risk factors remains unresolved as is the value of attempting to routinely diagnose subclinical disease with measurements such as the coronary calcium score.

Left ventricular dysfunction and extravascular fluid in the lung: physiological basis for symptoms.

The essential feature of left ventricular dysfunction is an increase in left atrial pressure and pulmonary venous congestion leading to a fluid flux across the pulmonary microvasculature. Small acute increases (< 10 mmHg) in left atrial pressure enhance the extravascular fluid volume in the airways and activate the rapidly adapting receptors (RAR). With larger increases in left atrial pressure (approximately 25 mmHg) both the RAR and the C-fiber receptors in the airways and the alveoli are activated. Activation of RAR causes a reflex increase in respiratory rate, tracheal tone and mucus secretion from the airways. It appears that small increases in extravascular fluid volume of the airways also cause a reflex diuresis which is mediated by activation of neuronal nitric oxide synthase in the renal medulla. In contrast, when left atrial pressure is elevated chronically, further small increments in extravascular fluid volume of the airways no longer stimulate the RAR. The reflex diuresis is also not evident under these circumstances. However, the RAR continue to be activated by increments in left atrial pressure in excess of 25 mmHg. It is suggested that the RAR of the airways play a significant role in monitoring changes in the extravascular fluid volume of the airways and mediate the reflexes which are associated with the symptomatology of acute left ventricular dysfunction.

Mechanism of the endothelium-dependent relaxation evoked by a grape seed extract.

GSEs (grape seed extracts) which contain polyphenolic compounds cause an endothelium-dependent relaxation of blood vessels. The aim of the present study was to examine the mechanisms involved in this response. A well-characterized GSE was applied to rabbit aortic rings suspended in organ baths containing Krebs-Henseleit buffer maintained at 37 degrees C. In aortic rings pre-contacted with noradrenaline (norepinephrine), the extract produced a dose-dependent relaxation. The maximum relaxations elicited by the extract (71.9+/-1.0%) were similar to those elicited by acetylcholine (64.2+/-1.5%) (n=12 for each). As expected, the relaxations were abolished by removal of the endothelium and by prior incubation with L-NAME (N(G)-nitro-L-arginine methyl ester), confirming the essential role of eNOS (endothelial NO synthase) in the response. The responses to the GSE were also abolished by incubation with wortmannin and LY294002, which are inhibitors of PI3K (phosphoinositide 3-kinase). These compounds had no effect on the responses to acetylcholine. Using immunoblotting, we also demonstrated that the GSE induced the phosphorylation of both Akt and eNOS in HUVECs (human umbilical vein endothelial cells). Finally, the extract was modified by methylation of the hydroxy groups in the polyphenolic groups and was applied to the aortic rings. The modified extract failed to cause a relaxation. Taken together, these findings suggest that the endothelium-dependent relaxation induced by the GSE was mediated by activation of the PI3K/Akt signalling pathway through a redox-sensitive mechanism, resulting in phosphorylation of eNOS.

Effects of mitral regurgitation on the reflex diuresis to pulmonary lymphatic obstruction in rabbits.

Increasing the extravascular fluid of the airways acutely by obstructing pulmonary lymph drainage causes a reflex diuresis mediated by neuronal nitric oxide synthase in the renal medulla. The authors examined this reflex in rabbits with a chronic increase in extravascular fluid of the airways resulting from surgically induced mitral regurgitation. Intact rabbits served as controls. Renal neuronal (nNOS) and endothelial (eNOS) nitric oxide synthase expressions were also examined. The reflex was absent in rabbits with mitral regurgitation. There were significant increases in medullary and cortical nNOS mRNA compared to controls. The observed changes in mRNA levels correlated with nNOS protein levels. eNOS mRNA was unaffected.

Cardiac event rate in a lifestyle modification program for patients with chronic coronary artery disease.

BACKGROUND: Several clinical trials have shown that intensive lifestyle modification programs have a significant impact on cardiovascular risk factors. HYPOTHESIS: This paper is a retrospective analysis to determine the effect of participation in a 2-year lifestyle management program on long-term clinical outcome in patients outside the setting of a clinical trial. METHODS: Patients with angiographically confirmed coronary artery disease (CAD) enrolled in a 2-year program of exercise training, dietary counseling, stress management, and therapeutic education. They were accepted into the program from 1991 through December 2002. Follow-up after completion of the program ranged from 10 to 2 years. RESULTS: In all, 134 patients enrolled in the program; of these, 77 completed the program and 57 failed to do so. Those who completed the program improved their effort tolerance and reached recommended goals for serum lipid and blood pressure levels. The cumulative event rate (cardiac death, myocardial infarction, and stroke) over 10 years in the patients who completed the program was 1.5%. The corresponding event rate in patients who dropped out was 18% (p < 0.02). CONCLUSIONS: It is suggested that patients who complete a 2-year lifestyle modification program appear to have a favorable prognosis over an extended period of time.

The rapidly adapting receptors in mammalian airways and their responses to changes in extravascular fluid volume.

In this short review, we shall focus on some recent findings on the physiological stimulus for the rapidly adapting receptors (RAR) of the airways. They are readily activated by a sustained inflation of the lungs and they are usually identified by their rapid adaptation to this stimulus. They are also activated by both tactile stimuli and irritant gases applied to the epithelium of the airways. The investigations reviewed here suggest that these receptors are activated by changes in extravascular fluid volume. The principal factors governing fluid flux from the microcirculation are identified in the Starling equation. These are the hydrostatic pressure, plasma oncotic pressure and capillary permeability. Findings from recent studies suggest that all these factors increase the activity of RAR. In addition, these receptors are also activated by obstruction of lymph drainage from the lung. Evidence is presented to show that manipulation of Starling forces also increases the extravascular fluid volume of the airways in areas where the RAR are located. On the basis of these findings, it is suggested that, along with mechanosensitivity to stimuli such as stretch, inflation and deflation, another physiological stimulus to the RAR is a change in extravascular fluid volume in the regions of the airways where these receptors are located.

Effect of fatty acids on endothelium-dependent relaxation in the rabbit aorta.

The metabolic syndrome, Type II (non-insulin-dependent) diabetes and obesity are associated with endothelial dysfunction and increased plasma concentrations of NEFAs (non-esterified fatty acids; free fatty acids). The present study was undertaken to define the inhibitory effects of saturated NEFAs on EDR (endothelium-dependent relaxation). Experiments were performed in rings of rabbit aorta to establish (i) dose-response relationships, (ii) the effect of chain length, (iii) the effect of the presence of double bonds, (iv) reversibility and time course of inhibition, and (v) the effect on nitric oxide production. Aortic rings were incubated (1 h) with NEFA-albumin complexes derived from lauric (C(12:0)), myristic (C(14:0)), palmitic (C(16:0)), stearic (C(18:0)) and linolenic (C(18:3)) acids. EDR induced by acetylcholine (0.1-10 mumol/l) was measured after pre-contraction with noradrenaline. Inhibition of EDR was dose-dependent (0.5-2 mmol/l NEFA), and the greatest inhibition (51%) was observed with stearic acid (2 mmol/l). Lauric acid had the smallest inhibitory effect. The inhibitory effects were always reversible and were evident after 15 min of incubation. Linolenic acid caused a significantly lower inhibition of EDR than stearic acid. SOD (superoxide dismutase) restored the inhibitory effect caused by NEFAs, suggesting the involvement of ROS (reactive oxygen species) in removing nitric oxide. The nitric oxide concentration measured after exposure of the rings to acetylcholine was lower after incubation with NEFAs than with Krebs buffer alone. This finding is consistent with removal of nitric oxide by ROS. This claim was supported by the demonstration of increased concentrations of nitrated tyrosine in the rings incubated with NEFAs.

Counterpoint: carotid ultrasound-an essential investigation in the prevention of coronary artery disease?

The accompanying article asserts that measurement of carotid plaque area by ultrasonography adds a vital, new dimension to the investigation and management of patients at risk of developing coronary artery disease. The author contends also that traditional risk factors for coronary artery disease have failed to provide a basis for either predicting cardiovascular events or guiding effective therapy. Carefully acquired epidemiological data have established beyond reasonable doubt that traditional risk factors identify individuals who are likely to develop coronary artery disease. Further, effective management of these factors have been remarkably effective in preventing cardiovascular events. There is little prospective data in randomly selected populations to indicate that ultrasound examinations of the carotid arteries provides additional new information which would argue in favor of an alternative therapeutic approach for patients likely to develop coronary artery disease.

Role of adrenergic receptors in the reflex diuresis in rabbits during pulmonary lymphatic obstruction.

The role of adrenergic receptors in the reflex diuresis in response to pulmonary lymphatic drainage was examined in anaesthetized, artificially ventilated New Zealand White rabbits. Pulmonary lymphatic drainage was obstructed by raising the pressure in a pouch created from the right external jugular vein. This pulmonary lymphatic obstruction results in a reflex increase in urine flow and sodium excretion. This reflex is abolished by renal denervation and by administration of L-NAME, a non-selective inhibitor of nitric oxide synthase. Also, infusion of the relatively selective neuronal nitric oxide synthase blocker, 7-nitroindazole sodium salt, into the renal medulla abolished the reflex diuresis. In this study the effects of adrenergic receptor antagonists on the reflex increase in urine were observed. Both ureters were cannulated in order to determine urine flow from both kidneys separately. Prazosin, an alpha1 adrenergic receptor antagonist, was infused into the renal medulla of the right kidney, while the left kidney acted as control. Administration of prazosin in this manner did not block the reflex diuresis in response to pulmonary lymphatic obstruction in either kidney. However, rauwolscine, an alpha2 adrenergic receptor antagonist, abolished the reflex increase in urine and sodium excretion in the ipsilateral kidney while preserving it in the contralateral kidney. These findings suggest that the increase in urine flow in rabbits caused by pulmonary lymphatic obstruction is dependent upon activation of alpha2 adrenergic receptors within the renal medulla.

Effects of gadolinium chloride on slowly adapting and rapidly adapting receptors of the rabbit lung.

Effects of gadolinium chloride, an inhibitor of stretch-activated channels, on the responses of slowly adapting receptors (SARs) and rapidly adapting receptors (RARs) to hyperinflation were investigated. The increase in activity of RARs resulting from sustained elevations of left atrial pressure (LAP) was also assessed with gadolinium chloride application. Action potentials (AP) of SARs and RARs during hyperinflation were recorded from the vagus nerve of anesthetized New Zealand White rabbits before and after application of gadolinium chloride (20mM) directly on the receptor area of the nerve endings. There was a significant reduction of activity in SARs (n = 9) and RARs (n = 7) after application of gadolinium chloride. Activity of RARs (n = 6) increased when the LAP was elevated by 5 and 10 mmHg. This effect was abolished after gadolinium chloride was applied to receptor endings and the activity was restored when gadolinium chloride was removed. This suggests that stretch-activated channels play a role in SARs and RARs activity.

Role of nitric oxide in the reflex diuresis in rabbits during pulmonary lymphatic obstruction.

The role of nitric oxide in the reflex diuresis in response to pulmonary lymphatic drainage was examined in anaesthetized, artificially ventilated New Zealand White rabbits. Pulmonary lymphatic drainage was obstructed by raising the pressure in a pouch created from the right external jugular vein. Pulmonary lymphatic obstruction resulted in a significant increase in urine flow from an initial control value of 8.9 +/- 0.5 ml (10 min)(-1) to 12.1 +/- 0.6 ml (10 min)(-1) during lymphatic obstruction (mean +/-s.e.m.; n= 17, P < 0.001). This increase in urine flow was accompanied by a significant increase in the excretion of sodium. Additionally, renal blood flow remained unchanged during the increase in urine flow caused by lymphatic obstruction. Intravenous infusion of L-NAME, a non-selective inhibitor of nitric oxide synthase (NOS), abolished the reflex diuresis. Furthermore, intraperitoneal administration of the relatively selective neuronal NOS blocker, 7-nitroindazole also abolished the response. It was observed that infusion of a more soluble neuronal NOS blocker, 7-nitroindazole sodium salt (7-NINA), into the renal medulla also abolished the reflex diuresis. These findings suggest that the increase in urine flow in rabbits caused by pulmonary lymphatic obstruction is dependent upon the integrity of neuronal NOS activity within the renal medulla.