Are the cardiovascular properties of GLP-1 receptor agonists differentially modulated by sulfonylureas? Insights from post-hoc analysis of EXSCEL.

AIMS: To examine whether the cardiovascular effects of glucagon-like peptide-1 (GLP-1) receptor agonists are attenuated by concurrent sulfonylurea (SU) therapy in a post-hoc analysis of the Exenatide Study of Cardiovascular Event Lowering (EXSCEL). METHODS: We investigated whether SUs, as a class or by specific type, modulated the effects of once-weekly exenatide (EQW) on EXSCEL cardiovascular outcomes in intent-to-treat analyses of all trial participants, categorized as SU users or nonusers. Marginal structural models were used to evaluate whether there were differential EQW effects by SU category on major adverse cardiovascular events (MACE), depending on duration of SU use (6, 12, and 18 months). EQW-by-SU type interaction p-values and hazard ratios (95 % CIs) for EQW versus placebo for each baseline SU type (glibenclamide, gliclazide, glimepiride, other SUs) were calculated. RESULTS: Neither SU use nor baseline SU type modified the effect of EQW on time to MACE (pinteraction = 0.88 and 0.78, respectively), nor did individual SU types, including glibenclamide (a systemically wide-acting SU). CONCLUSIONS: SUs did not modulate the effect of EQW on cardiovascular outcomes, suggesting that SU treatment choices need not be altered to optimize the cardiovascular effects of GLP-1 receptor agonists in people with type 2 diabetes.

Type 2 diabetes exacerbates changes in blood pressure-independent arterial stiffness: cross-sectional and longitudinal evidence from the SUMMIT study.

Greater central artery stiffness is observed in people with type 2 diabetes (T2DM). Elevated blood pressure (BP) and altered arterial wall structure/composition in T2DM are generally considered as main drivers for this alteration. However, because conventional arterial stiffness measures are BP-dependent and as such an influence of BP remains in a measure, it is unclear if greater central artery stiffness is a function of greater BP, or due to changes in the structure and composition of the arterial wall. We aimed to measure BP-independent arterial stiffness (ß0) cross-sectionally and longitudinally in T2DM. We studied 753 adults with T2DM (DM+) and 436 adults without (DM-) at baseline (Phase 1), and 310 DM+ and 210 DM- adults at 3-yr follow-up (Phase 2). We measured carotid-femoral pulse wave velocity and used it to calculate ß0. In Phase 1, ß0 was significantly greater in DM+ than DM- after adjusting for age and sex [27.5 (26.6-28.3) vs. 23.6 (22.4-24.8) au, P < 0.001]. Partial correlation analyses after controlling for age and sex showed that ß0 was significantly associated with hemoglobin A1c (r = 0.15 P < 0.001) and heart rate [(HR): r = 0.23 P < 0.001)] in DM+. In Phase 2, percentage-change in ß0 was significantly greater in DM+ than DM- [19.5 (14.9-24.0) vs. 5.0 (-0.6 to 10.6) %, P < 0.001] after adjusting for age, sex, and baseline ß0. ß0 was greater in DM+ than DM- and increased much more in DM+ than in DM- over 3 yr. This suggests that T2DM exacerbates BP-independent arterial stiffness and may have a complemental utility to existing arterial stiffness indices.NEW & NOTEWORTHY We demonstrate in this study a greater BP-independent arterial stiffness ß0 in people with type 2 diabetes (T2DM) compared to those without, and also a greater change in ß0 over 3 yr in people with T2DM than those without. These findings suggest that the intrinsic properties of the arterial wall may change in a different and more detrimental way in people with T2DM and likely represents accumulation of cardiovascular risk.

Genome-wide mRNA profiling in urinary extracellular vesicles reveals stress gene signature for diabetic kidney disease.

Urinary extracellular vesicles (uEV) are a largely unexplored source of kidney-derived mRNAs with potential to serve as a liquid kidney biopsy. We assessed ∼200 uEV mRNA samples from clinical studies by genome-wide sequencing to discover mechanisms and candidate biomarkers of diabetic kidney disease (DKD) in Type 1 diabetes (T1D) with replication in Type 1 and 2 diabetes. Sequencing reproducibly showed >10,000 mRNAs with similarity to kidney transcriptome. T1D DKD groups showed 13 upregulated genes prevalently expressed in proximal tubules, correlated with hyperglycemia and involved in cellular/oxidative stress homeostasis. We used six of them (GPX3, NOX4, MSRB, MSRA, HRSP12, and CRYAB) to construct a transcriptional "stress score" that reflected long-term decline of kidney function and could even identify normoalbuminuric individuals showing early decline. We thus provide workflow and web resource for studying uEV transcriptomes in clinical urine samples and stress-linked DKD markers as potential early non-invasive biomarkers or drug targets.

Reservoir Pressure Integral Is Independently Associated With the Reduction in Renal Function in Older Adults.

BACKGROUND: Arterial hemodynamic parameters derived from reservoir-excess pressure analysis exhibit prognostic utility. Reservoir-excess pressure analysis may provide useful information about an influence of altered hemodynamics on target organ such as the kidneys. We determined whether the parameters derived from the reservoir-excess pressure analysis were associated with the reduction in estimated glomerular filtration rate in 542 older adults (69.4±7.9 years, 194 females) at baseline and after 3 years. METHODS: Reservoir-excess pressure parameters, including reservoir pressure integral, excess pressure integral, systolic, and diastolic rate constants, were obtained by radial artery tonometry. RESULTS: After 3 years, and in a group of 94 individuals (72.4±7.6 years, 26 females), there was an estimated glomerular filtration rate reduction of >5% per year (median reduction of 20.5% over 3 years). A multivariable logistic regression analysis revealed that higher baseline reservoir pressure integral was independently associated with a smaller reduction in estimated glomerular filtration rate after accounting for conventional cardiovascular risk factors and study centers (odds ratio: 0.660 [95% CIs, 0.494-0.883]; P=0.005). The association remained unchanged after further adjustments for potential confounders and baseline renal function (odds ratio: 0.528 [95% CIs, 0.351-0.794]; P=0.002). No other reservoir-excess pressure parameters exhibited associations with the reduction in renal function. CONCLUSIONS: This study demonstrates that baseline reservoir pressure integral was associated with the decline in renal function in older adults at 3-year follow-up, independently of conventional cardiovascular risk factors. This suggests that reservoir pressure integral may play a role in the functional decline of the kidneys.

Plaque characteristics and biomarkers predicting regression and progression of carotid atherosclerosis.

The factors that influence the atherosclerotic disease process in high-risk individuals remain poorly understood. Here, we used a combination of vascular imaging, risk factor assessment, and biomarkers to identify factors associated with 3-year change in carotid disease severity in a cohort of high-risk subjects treated with preventive therapy (n = 865). The results show that changes in intima-media thickness (IMT) are most pronounced in the carotid bulb. Progression of bulb IMT demonstrates independent associations with baseline bulb IMT, the plaque gray scale median (GSM), and the plasma level of platelet-derived growth factor (PDGF) (standardized ß-coefficients and 95% confidence interval [CI] -0.14 [-0.06 to -0.02] p = 0.001, 0.15 [0.02-0.07] p = 0.001, and 0.20 [0.03-0.07] p < 0.001, respectively). Plasma PDGF correlates with the plaque GSM (0.23 [0.15-0.29] p < 0.001). These observations provide insight into the atherosclerotic process in high-risk subjects by showing that progression primarily occurs in fibrotic plaques and is associated with increased levels of PDGF.

Carotid-femoral pulse wave velocity acquisition methods and their associations with cardiovascular risk factors and subclinical biomarkers of vascular health.

BACKGROUND: Different methods to measure carotid-femoral pulse wave velocity (CFPWV) may affect the measurements obtained and influence the association between CFPWV, cardiovascular risk factors and biomarkers of subclinical vascular health. The estimation of distance between the carotid and femoral artery measurement sites (the arterial path length) is particularly problematic. METHOD: We determined if CFPWV and equation-based estimates of CFPWV were influenced by arterial path length and if this affected the association of CFPWV with cardiovascular risk factors and subclinical vascular biomarkers. The CFPWV derived from the measurement of surface distance (CFPWV-D), arterial path length formula (CFPWV-F), and estimated CFPWV (ePWV) were obtained from 489 older adults (67.2 ±â€Š8.8 years). Macrovascular [carotid artery: lumen diameter (LD), inter-adventitial diameter (IAD), intima-media thickness (IMT) and total plaque area (TPA)] and microvascular [reactive hyperaemia index and urinary albumin-creatinine ratio (UACR)] biomarkers were also measured. RESULTS: CFPWV-D was significantly greater than CFPWV-F [9.6 (8.0-11.2) vs. 8.9 (7.6-10.5) m/s, P < 0.001], because of estimated path length being longer in CFPWV-D than CFPWV-F (495.4 ±â€Š44.8 vs. 465.3 ±â€Š20.6 mm, P < 0.001). ePWV was significantly greater than both CFPWV-F and CFPWV-D [11.0 (10.0-12.2) m/s, P < 0.001]. The three CFPWV methods were similarly associated with LD, IAD, IMT, TPA and UACR but not with cardiovascular risk factors. CONCLUSION: Different methods to measure CFPWV affect the derived measurement values and the association with cardiovascular risk factors but not the association with subclinical biomarkers of vascular health. These hitherto unreported observations are important considerations in experimental design, data interpretation and of particular importance, comparison between studies where CFPWV is measured.

Reservoir-Excess Pressure Parameters Independently Predict Cardiovascular Events in Individuals With Type 2 Diabetes.

[Figure: see text].

Prognostic imaging biomarkers for diabetic kidney disease (iBEAt): study protocol.

BACKGROUND: Diabetic kidney disease (DKD) remains one of the leading causes of premature death in diabetes. DKD is classified on albuminuria and reduced kidney function (estimated glomerular filtration rate (eGFR)) but these have modest value for predicting future renal status. There is an unmet need for biomarkers that can be used in clinical settings which also improve prediction of renal decline on top of routinely available data, particularly in the early stages. The iBEAt study of the BEAt-DKD project aims to determine whether renal imaging biomarkers (magnetic resonance imaging (MRI) and ultrasound (US)) provide insight into the pathogenesis and heterogeneity of DKD (primary aim) and whether they have potential as prognostic biomarkers in DKD (secondary aim). METHODS: iBEAt is a prospective multi-centre observational cohort study recruiting 500 patients with type 2 diabetes (T2D) and eGFR ≥30 ml/min/1.73m2. At baseline, blood and urine will be collected, clinical examinations will be performed, and medical history will be obtained. These assessments will be repeated annually for 3 years. At baseline each participant will also undergo quantitative renal MRI and US with central processing of MRI images. Biological samples will be stored in a central laboratory for biomarker and validation studies, and data in a central data depository. Data analysis will explore the potential associations between imaging biomarkers and renal function, and whether the imaging biomarkers improve the prediction of DKD progression. Ancillary substudies will: (1) validate imaging biomarkers against renal histopathology; (2) validate MRI based renal blood flow measurements against H2O15 positron-emission tomography (PET); (3) validate methods for (semi-)automated processing of renal MRI; (4) examine longitudinal changes in imaging biomarkers; (5) examine whether glycocalyx and microvascular measures are associated with imaging biomarkers and eGFR decline; (6) explore whether the findings in T2D can be extrapolated to type 1 diabetes. DISCUSSION: iBEAt is the largest DKD imaging study to date and will provide valuable insights into the progression and heterogeneity of DKD. The results may contribute to a more personalised approach to DKD management in patients with T2D. TRIAL REGISTRATION: Clinicaltrials.gov ( NCT03716401 ).

Weight change and sulfonylurea therapy are related to 3 year change in microvascular function in people with type 2 diabetes.

AIMS/HYPOTHESIS: Although cardiovascular disease is the biggest cause of death in people with diabetes, microvascular complications have a significant impact on quality of life and financial burden of the disease. Little is known about the progression of microvascular dysfunction in the early stages of type 2 diabetes before the occurrence of clinically apparent complications. We aimed to explore the determinants of endothelial-dependent and -independent microvascular function progression over a 3 year period, in people with and without both diabetes and few clinical microvascular complications. METHODS: Demographics were collected in 154 participants with type 2 diabetes and in a further 99 participants without type 2 diabetes. Skin microvascular endothelium-dependent response to iontophoresis of acetylcholine and endothelium-independent responses to sodium nitroprusside were measured using laser Doppler fluximetry. All assessments were repeated 3 years later. RESULTS: People with type 2 diabetes had impaired endothelial-dependent microvascular response compared with those without (AUC 93.9 [95% CI 88.1, 99.4] vs 111.9 [102.3, 121.4] arbitrary units [AU] × min, p < 0.001, for those with vs without diabetes, respectively). Similarly, endothelial-independent responses were attenuated in those with diabetes (63.2 [59.2, 67.2] vs 75.1 [67.8, 82.4] AU × min, respectively, p = 0.002). Mean microvascular function declined over 3 years in both groups to a similar degree (pinteraction 0.74 for response to acetylcholine and 0.69 for response to sodium nitroprusside). In those with diabetes, use of sulfonylurea was associated with greater decline (p = 0.022 after adjustment for co-prescriptions, change in HbA1c and weight), whereas improving glycaemic control was associated with less decline of endothelial-dependent microvascular function (p = 0.03). Otherwise, the determinants of microvascular decline were similar in those with and without diabetes. The principal determinant of change in microvascular function in the whole population was weight change over 3 years, such that those that lost ≥5% weight had very little decline in either endothelial-dependent or -independent function compared with those that were weight stable, whereas those who gained weight had a greater decline in function (change in endothelial-dependent function was 1.2 [95% CI -13.2, 15.7] AU × min in those who lost weight; -15.8 [-10.5, -21.0] AU × min in those with stable weight; and -37.8 [-19.4, -56.2] AU × min in those with weight gain; ptrend < 0.001). This association of weight change with change in endothelial function was driven by people with diabetes; in people without diabetes, the relationship was nonsignificant. CONCLUSIONS/INTERPRETATION: Over 3 years, physiological change in weight was the greatest predictor of change in microvascular function.

A Mendelian Randomization Study Provides Evidence That Adiposity and Dyslipidemia Lead to Lower Urinary Albumin-to-Creatinine Ratio, a Marker of Microvascular Function.

Urinary albumin-to-creatinine ratio (ACR) is a marker of diabetic nephropathy and microvascular damage. Metabolic-related traits are observationally associated with ACR, but their causal role is uncertain. Here, we confirmed ACR as a marker of microvascular damage and tested whether metabolic-related traits have causal relationships with ACR. The association between ACR and microvascular function (responses to acetylcholine [ACH] and sodium nitroprusside) was tested in the SUMMIT study. Two-sample Mendelian randomization (MR) was used to infer the causal effects of 11 metabolic risk factors, including glycemic, lipid, and adiposity traits, on ACR. MR was performed in up to 440,000 UK Biobank and 54,451 CKDGen participants. ACR was robustly associated with microvascular function measures in SUMMIT. Using MR, we inferred that higher triglyceride (TG) and LDL cholesterol (LDL-C) levels caused elevated ACR. A 1 SD higher TG and LDL-C level caused a 0.062 (95% CI 0.040, 0.083) and a 0.026 (95% CI 0.008, 0.044) SD higher ACR, respectively. There was evidence that higher body fat and visceral body fat distribution caused elevated ACR, while a metabolically "favorable adiposity" phenotype lowered ACR. ACR is a valid marker for microvascular function. MR suggested that seven traits have causal effects on ACR, highlighting the role of adiposity-related traits in causing lower microvascular function.

Locally delivered GLP-1 analogues liraglutide and exenatide enhance microvascular perfusion in individuals with and without type 2 diabetes.

AIMS/HYPOTHESIS: Glucagon-like peptide-1 (GLP-1) analogues reduce the risk of macrovascular disease in diabetes; however, little is known about their microvascular effects. This research examined the microvascular actions of the GLP-1 analogues liraglutide and exenatide in individuals with and without type 2 diabetes (study 1). It also explored the involvement of the GLP-1 receptor (study 2) and the nitric oxide pathway in mediating the microvascular effects of the analogues. METHODS: Trial design: Studies 1 and 2 had a randomised, controlled, double-blind study design. Study 1 participants, intervention and methods: three participant groups were recruited: individuals with well-controlled type 2 diabetes, and obese and lean individuals without diabetes (21 participants per group). Liraglutide (0.06 mg), exenatide (0.5 µg) and saline (154 mmol/l NaCl; 0.9%) control were microinjected into separate sites in the dermis (forearm) in a randomised order, blinded to operator and participant. Skin microvascular perfusion was assessed by laser Doppler perfusion imaging. Outcomes were stabilised response (mean skin perfusion between 7.5 and 10 min post microinjection) and total response (AUC, normalised for baseline perfusion). Perfusion response to GLP-1 analogues was compared with saline within each group as well as between groups. Study 2 participants, intervention and methods: in healthy individuals (N = 16), liraglutide (0.06 mg) and saline microinjected sites were pretreated with saline or the GLP-1 receptor blocker, exendin-(9,39), in a randomised order, blinded to participant and operator. Outcomes were as above (stabilised response and total perfusion response). Perfusion response to liraglutide was compared between the saline and the exendin-(9,39) pretreated sites. In vitro study: the effects of liraglutide and exenatide on nitrate levels and endothelial nitric oxide synthase phosphorylation (activation) were examined using human microvascular endothelial cells. RESULTS: Study 1 results: both analogues increased skin perfusion (stabilised response and total response) in all groups (n = 21 per group, p < 0.001), with the microvascular responses similar across groups (p ≥ 0.389). Study 2 results: liraglutide response (stabilised response and total response) was not influenced by pretreatment with exendin-(9,39) (70 nmol/l) (N = 15, one dataset excluded) (p ≥ 0.609). Liraglutide and exenatide increased nitrate production and endothelial nitric oxide synthase (eNOS) phosphorylation (p ≤ 0.020). CONCLUSIONS/INTERPRETATION: Liraglutide and exenatide increased skin microvascular perfusion in individuals with and without well-controlled diabetes, potentially mediated, at least in part, by NO. TRIAL REGISTRATION: ClinicalTrials.gov NCT01677104. FUNDING: This work was supported by Diabetes UK (grant numbers: 09/0003955 and 12/0004600 [RW and JM Collins Legacy, Funded Studentship]).

Stability of urinary albumin and creatinine after 12 months storage at -20 °C and -80 °C.

BACKGROUND: Increasing albumin to creatinine ratio (ACR) within the normal range is a risk factor for cardiovascular disease in the general population. Clinical and epidemiological studies often store urine samples for long durations prior to ACR assessment. The stability of ACR at the lowest urinary albumin concentrations during prolonged storage has not been previously studied because routine clinical assays can't quantify very low concentrations of albumin. AIM: To determine the stability of urinary albumin and creatinine over 12 months in samples stored at -20 °C and -80 °C using an assay which enables assessment of previously undetectable levels of albumin and to investigate if additives can be used to prevent urinary albumin degradation. METHOD: ACR was measured in 30 urine samples from healthy subjects on the day of collection. Each sample was divided into 5 portions, each receiving a different treatment; alkalisation, protease inhibiter, boric acid, low protein binding tubes and no treatment (control). Samples were stored at -20 °C and -80 °C and ACR was analysed again after 12 months. RESULTS: Mean (95% CI) percent change in ACR was -34.3% (-47.2 to -21.4; p < 0.0001) and -1.8% (-9.4 to 5.8; p = 0.91) in samples stored at -20 °C and -80 °C respectively. Treating samples did not prevent the reduction in albumin at -20 °C (p < 0.001). CONCLUSION: The loss in urinary albumin concentration which occurs during storage at -20 °C for 12 months is not prevented by pre-treating samples prior to storage. For accurate determination of albumin concentration or ACR, samples should be stored at -80 °C on day of collection.

Intraoperative Tissue Perfusion Measurement by Laser Speckle Imaging: A Potential Aid for Reducing Postoperative Complications in Free Flap Breast Reconstruction.

Adequate tissue perfusion is essential to minimize postoperative complications following microsurgery. Intraoperative knowledge of tissue perfusion could aid surgical decision-making and result in reduced complications. Laser speckle imaging is a new, noninvasive technique for mapping tissue perfusion. This article discusses the feasibility of using laser speckle imaging during free flap breast reconstruction and its potential to identify areas of inadequate perfusion, thus reducing surgical complications. Adult patients scheduled to undergo free flap breast reconstruction were recruited into the study. Laser speckle images were obtained from the abdominal and breast areas at different stages intraoperatively. Zonal perfusion was compared with the Holm classification and clinical observations. Twenty patients scheduled to undergo free flap breast reconstruction were recruited (23 reconstructed breasts) (mean age, 50 years; range, 32 to 68 years). Flap zonal perfusion was 238 (187 to 313), 222 (120 to 265), 206 (120 to 265), and 125 (102 to 220) perfusion units for zones I, II, III, and IV, respectively (analysis of variance, p < 0.0001). Zonal area with perfusion below an arbitrary perfusion threshold were 20 (0.3 to 75), 41 (3 to 99), 49 (9 to 97), and 99 (25 to 100) percent, respectively (analysis of variance, p < 0.0001). One example is presented to illustrate potential intraoperative uses for laser speckle imaging. This study shows that laser speckle imaging is a feasible, noninvasive technique for intraoperative mapping of tissue perfusion during free flap breast reconstruction. Zonal tissue perfusion was reduced across the Holm classification. Observations indicated the potential for laser speckle imaging to provide additional information to augment surgical decision-making by detection of inadequate tissue perfusion. This highlights the opportunity for surgeons to consider additional aids for intraoperative tissue perfusion assessment to help reduce perfusion-related complications. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Diagnostic, IV.

GLP-1 analogue-induced weight loss does not improve obesity-induced AT dysfunction.

Glucagon-like peptide-1 (GLP-1) analogues aid weight loss that improves obesity-associated adipose tissue (AT) dysfunction. GLP-1 treatment may however also directly influence AT that expresses the GLP-1 receptor (GLP-1R). The present study aimed to assess the impact of GLP-1 analogue treatment on subcutaneous AT (SCAT) inflammatory and fibrotic responses, compared with weight loss by calorie reduction (control). Among the 39 participants with Type 2 diabetes recruited, 30 age-matched participants were randomized to 4 months treatment with Liraglutide (n=22) or calorie restriction based on dietetic counselling (n=8). Assessments included clinical characteristics and repeated subcutaneous abdominal AT biopsies. Liraglutide resulted in weight loss in most participants (-3.12±1.72 kg, P=0.007) and significant reduction in visceral AT (VAT). It was more effective in lowering fasting glucose, in comparison with weight loss by dieting. However, tumour necrosis factor-α (TNFA) AT-expression (P=0.0005), macrophage chemoattractant protein-1 (MCP-1) expression (P=0.027) and its serum levels (P=0.048) increased with Liraglutide, suggestive of an inflammatory response unlike in the diet arm in which a trend of lower cluster of differentiation 14 (CD14) expression (P=0.09) was found. Liraglutide treatment also increased expression of factors involved in extracellular matrix (ECM) deposition, transforming growth factor-ß (TGFB) and collagen type 1 alpha 1 chain (COL1A1) (TGFB1: before 0.73±0.09 arbitrary units (AU), after 1.00±0.13 AU, P=0.006; COL1A1: 0.84±0.09 AU compared with 1.49±0.26 AU, P=0.026). Liraglutide thus appears to induce an inflammatory response in AT and influences ECM remodelling. Despite its superior effect on glycaemia, Liraglutide does not improve obesity-associated AT dysfunction in subcutaneous tissue. It is yet unclear whether this limits AT storage capacity for lipids. This may be of importance in patients being re-exposed to positive energy balance such as post GLP-1 discontinuation.

Reactivity to low-flow as a potential determinant for brachial artery flow-mediated vasodilatation.

Previous studies have reported a vasoconstrictor response in the radial artery during a cuff-induced low-flow condition, but a similar low-flow condition in the brachial artery results in nonuniform reactivity. This variable reactivity to low-flow influences the subsequent flow-mediated dilatation (FMD) response following cuff-release. However, it is uncertain whether reactivity to low-flow is important in data interpretation in clinical populations and older adults. This study aimed to determine the influence of reactivity to low-flow on the magnitude of brachial artery FMD response in middle-aged and older individuals with diverse cardiovascular risk profiles. Data were analyzed from 165 individuals, divided into increased cardiovascular risk (CVR: n = 115, 85M, 67.0 ± 8.8 years) and healthy control (CTRL: n = 50, 30M, 63.2 ± 7.2 years) groups. Brachial artery diameter and blood velocity data obtained from Doppler ultrasound were used to calculate FMD, reactivity to low-flow and estimated shear rate (SR) using semiautomated edge-detection software. There was a significant association between reactivity to low-flow and FMD in overall (r = 0.261), CTRL (r = 0.410) and CVR (r = 0.189, all P < 0.05) groups. Multivariate regression analysis found that reactivity to low-flow, peak SR, and baseline diameter independently contributed to FMD along with sex, the presence of diabetes, and smoking (total R(2) = 0.450). There was a significant association between reactivity to low-flow and the subsequent FMD response in the overall dataset, and reactivity to low-flow independently contributed to FMD These findings suggest that reactivity to low-flow plays a key role in the subsequent brachial artery FMD response and is important in the interpretation of FMD data.

Echogenicity of the Common Carotid Artery Intima-Media Complex in Stroke.

The grey-scale median of the common carotid artery intima-media complex (IM-GSM) characterizes arterial wall composition, and a low IM-GSM is associated with increased cardiovascular mortality in the elderly. We aimed to determine differences in the IM-GSM between a cohort with cerebrovascular disease and a healthy cohort. Eighty-two healthy individuals (control group: 63.2 ± 8.7 y) and 96 patients with either stroke or transient ischemic attacks (CRVD group: 68.6 ± 9.8 y) were studied. Common carotid artery intima-media thickness and IM-GSM obtained by ultrasound were analyzed using semi-automated edge-detection software. The IM-GSM was significantly lower in the CRVD group than in the control group (106 ± 24 vs. 124 ± 27 au, p < 0.001). The IM-GSM was similar for the infarct and non-infarct sides in CRVD. In the pooled cohort of all participants, the lower the quartile of IM-GSM, the greater were the carotid artery intima-media thickness and carotid artery remodeling. These results suggest the presence of an altered atherosclerotic phenotype in the intima-media complex of CRVD patients that can be detected by ultrasound.

Red Blood Cell Susceptibility to Pneumolysin: CORRELATION WITH MEMBRANE BIOCHEMICAL AND PHYSICAL PROPERTIES.

This study investigated the effect of the biochemical and biophysical properties of the plasma membrane as well as membrane morphology on the susceptibility of human red blood cells to the cholesterol-dependent cytolysin pneumolysin, a key virulence factor of Streptococcus pneumoniae, using single cell studies. We show a correlation between the physical properties of the membrane (bending rigidity and surface and dipole electrostatic potentials) and the susceptibility of red blood cells to pneumolysin-induced hemolysis. We demonstrate that biochemical modifications of the membrane induced by oxidative stress, lipid scrambling, and artificial cell aging modulate the cell response to the toxin. We provide evidence that the diversity of response to pneumolysin in diabetic red blood cells correlates with levels of glycated hemoglobin and that the mechanical properties of the red blood cell plasma membrane are altered in diabetes. Finally, we show that diabetic red blood cells are more resistant to pneumolysin and the related toxin perfringolysin O relative to healthy red blood cells. Taken together, these studies indicate that the diversity of cell response to pneumolysin within a population of human red blood cells is influenced by the biophysical and biochemical status of the plasma membrane and the chemical and/or oxidative stress pre-history of the cell.

Detection of hydrogen sulfide in plasma and knee-joint synovial fluid from rheumatoid arthritis patients: relation to clinical and laboratory measures of inflammation.

Blood concentrations of hydrogen sulfide (H(2)S) are markedly elevated in several animal models of inflammation. Pharmacological inhibition of H(2)S synthesis reduces inflammation and swelling, suggesting that H(2)S is a potential inflammatory mediator. However, it is currently unknown whether H(2)S synthesis is perturbed in human inflammatory conditions or whether H(2)S is present in synovial fluid. We analyzed paired plasma and synovial fluid (SF) aspirates from rheumatoid arthritis (RA; n= 20) and osteoarthritis (OA; n= 4) patients and plasma from age matched healthy volunteers (n= 20). Median plasma H(2)S concentrations from healthy volunteers and RA and OA patients were 37.6, 36.6, and 37.6 microM, respectively. In RA patients, median synovial fluid H(2)S levels (62.4 microM) were significantly higher than paired plasma (P= 0.002) and significantly higher than in synovial fluid from OA patients (25.1 microM; P= 0.009). SF H(2)S levels correlated with clinical indices of disease activity (tender joint count, r= 0.651; P < 0.05) and markers of chronic inflammation; Europhile count (r=-0.566; P < 0.01) and total white cell count (r=-0.703; P < 0.01). Our study shows for the first time that H(2)S is present in synovial fluid and levels correlated with inflammatory and clinical indices in RA patients.

Maximum skin hyperaemia induced by local heating: possible mechanisms.

BACKGROUND: Maximum skin hyperaemia (MH) induced by heating skin to > or = 42 degrees C is impaired in individuals at risk of diabetes and cardiovascular disease. Interpretation of these findings is hampered by the lack of clarity of the mechanisms involved in the attainment of MH. METHODS: MH was achieved by local heating of skin to 42-43 degrees C for 30 min, and assessed by laser Doppler fluximetry. Using double-blind, randomized, placebo-controlled crossover study designs, the roles of prostaglandins were investigated by inhibiting their production with aspirin and histamine, with the H1 receptor antagonist cetirizine. The nitric oxide (NO) pathway was blocked by the NO synthase inhibitor, NG-nitro-L-arginine methyl esther (L-NAME), and enhanced by sildenafil (prevents breakdown of cGMP). RESULTS: MH was not altered by aspirin, cetirizine or sildenafil, but was reduced by L-NAME: median placebo 4.48 V (25th, 75th centiles: 3.71, 4.70) versus L-NAME 3.25 V (3.10, 3.80) (p = 0.008, Wilcoxon signed rank test). Inhibition of NO production (L-NAME) resulted in a more rapid reduction in hyperaemia after heating (p = 0.011), whereas hyperaemia was prolonged in the presence of sildenafil (p = 0.003). The increase in skin blood flow was largely confined to the directly heated area, suggesting that the role of heat-induced activation of the axon reflex was small. CONCLUSION: NO, but not prostaglandins, histamine or an axon reflex, contributes to the increase in blood flow on heating and NO is also a component of the resolution of MH after heating.