Metabolic and hemodynamic markers of endothelial dysfunction in patients with hypertension and patients with type 2 diabetes during the cold pressor test

The role of melatonin in the onset and progression of type 3 diabetes

Alzheimer’s disease (AD) is defined by the excessive accumulation of toxic peptides, such as beta amyloid (Aβ) plaques and intracellular neurofibrillary tangles (NFT). The risk factors associated with AD include genetic mutations, aging, insulin resistance, and oxidative stress. To date, several studies that have demonstrated an association between AD and diabetes have revealed that the common risk factors include insulin resistance, sleep disturbances, blood brain barrier (BBB) disruption, and altered glucose homeostasis. Many researchers have discovered that there are mechanisms common to both diabetes and AD. AD that results from insulin resistance in the brain is termed “type 3 diabetes”. Melatonin synthesized by the pineal gland is known to contribute to circadian rhythms, insulin resistance, protection of the BBB, and cell survival mechanisms. Here, we review the relationship between melatonin and type 3 diabetes, and suggest that melatonin might regulate the risk factors for type 3 diabetes. We suggest that melatonin is crucial for attenuating the onset of type 3 diabetes by intervening in Aβ accumulation, insulin resistance, glucose metabolism, and BBB permeability.

Influence of food patterns on endothelial biomarkers: a systematic review

The purpose of this study was to conduct a systematic review on the association of food patterns (FPs) and endothelial biomarkers. An electronic literature search from 1990 to 2012 was conducted and reference lists and experts were consulted. Studies without dietary intervention and without language restrictions were considered. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were employed. Methodological quality was assessed by Strengthening the Reporting of Observational Studies in Epidemiology guidelines. A total of 546 references were identified, of which 8 were finally included. Several FPs were identified. Healthy FPs (abundant in fruits and vegetables) had a beneficial impact on endothelial function as estimated by circulating levels of biomarkers such as C-reactive protein, soluble intercellular adhesion molecule 1, soluble vascular adhesion molecule 1, and E-selectin molecules. Westernized patterns (higher intakes of processed meats, sweets, fried foods, and refined grains) were positively associated with inflammation molecules and atherogenic promoters. The study of FPs in relation to endothelial function contributes to the development of dietary recommendations for improved cardiovascular health and therefore a better lifestyle.

Effects of varying degrees of intermittent hypoxia on proinflammatory cytokines and adipokines in rats and 3T3-L1 adipocytes

Objectives

Intermittent hypoxia (IH), resulted from recurring episodes of upper airway obstruction, is the hallmark feature and the most important pathophysiologic pathway of obstructive sleep apnea (OSA). IH is believed to be the most important factor causing systemic inflammation. Studies suggest that insulin resistance (IR) is positively associated with OSA. In this study, we hypothesized that the recurrence of IH might result in cellular and systemic inflammation, which was manifested through the levels of proinflammatory cytokines and adipokines after IH exposure, and because IR is linked with inflammation tightly, this inflammatory situation may implicate an IR status.

Methods

We developed an IH 3T3-L1 adipocyte and rat model respectively, recapitulating the nocturnal oxygen profile in OSA. In IH cells, nuclear factor kappa B (NF-κB) DNA binding reactions, hypoxia-inducible factor-1α (HIF-1α), glucose transporter-1 (Glut-1), necrosis factor alpha (TNF-α), interleukin (IL) -6, leptin, adiponectin mRNA transcriptional activities and protein expressions were measured. In IH rats, blood glucose, insulin, TNF-α, IL-6, leptin and adiponectin levels were analyzed.

Results

The insulin and blood glucose levels in rats and NF-κB DNA binding activities in cells had significantly statistical results described as severe IH>moderate IH>mild IH>sustained hypoxia>control. The mRNA and protein levels of HIF-1α and Glut-1 in severe IH group were the highest. In cellular and animal models, both the mRNA and protein levels of TNF-α, IL-6 and leptin were the highest in severe IH group, when the lowest in severe IH group for adiponectin.

Conclusions

Oxidative stress and the release of pro-inflammatory cytokines/adipokines, which are the systemic inflammatory markers, are associated with IH closely and are proportional to the severity of IH. Because IR and glucose intolerance are linked with inflammation tightly, our results may implicate the clinical relationships between OSA and IR.

Several lipid-related gene polymorphisms interact with overweight/obesity to modulate blood pressure levels

Little is known about the interactions of single nucleotide polymorphisms (SNPs) and overweight/obesity on blood pressure levels. The present study was undertaken to detect 10 lipid-related gene SNPs and their interactions with overweight/obesity on blood pressure levels. Genotyping of ATP-binding cassette transporter A1 (ABCA-1) V825I, acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) rs1044925, low density lipoprotein receptor (LDL-R) AvaII hepatic lipase gene (LIPC) −250G > A, endothelial lipase gene (LIPG) 584C > T, methylenetetrahydrofolate reductase (MTHFR) 677C > T, the E3 ubiquitin ligase myosin regulatory light chain-interacting protein (MYLIP) rs3757354, proprotein convertase subtilisin-like kexin type 9 (PCSK9) E670G, peroxisome proliferator-activated receptor delta (PPARD) +294T > C, and Scavenger receptor class B type 1 (SCARB1) rs5888 was performed in 978 normal weight and 751 overweight/obese subjects. The interactions were detected by factorial regression analysis. The genotypes of ACAT-1 AC, LIPC GA and AA, and SCARB1 TT; LDL-R A-A- and LIPC GA; and SCARB1 TT were interacted with overweight/obesity to increase systolic, diastolic blood pressure (SBP, DBP) and pulse pressure (PP) levels; respectively. The genotypes of ACAT-1 CC; ACAT-1 AA and CC were interacted with overweight/obesity to decrease SBP, PP levels (p < 0.01–0.001); respectively. The differences in blood pressure levels between normal weight and overweight/obese subjects might partly result from different interactions of several SNPs and overweight/obesity.

Inflammation status of rabbit carotid artery model endothelium during intermittent hypoxia exposure and its relationship with leptin

OBJECTIVES

To develop an intermittent hypoxia/reoxygenation (IH/ROX) rabbit carotid artery model and then investigate the inflammation status of rabbit carotid artery endothelium after IH exposure and its relationship with leptin.

MATERIALS AND METHODS

After anesthetization, rabbit's right common carotid artery was cleared of surrounding tissue with anatomic microscope, cannulated to its distal part and the proximal part was ligated. Preparations were challenged by changing the PO(2) of the gas mixture equilibrating the perfusate. Alternate perfusing (2 mL/min) of equilibrated perfusate bubbled with normoxia or hypoxia gas mixtures formed IH/ROX cycles in the right carotid common artery, simulating the pattern of hypoxic episodes seen in obstructive sleep apnea (OSA), or continuous perfusing of hypoxia perfusate to form continuous hypoxia (CH) modes. Sixty adult male New Zealand White rabbits (2.5-3.0 kg) were separated into six groups, ten per group. Groups were: A, intermittent normoxia (IN) group, perfused with perfusion equilibrated with 21% O(2) [PO(2) about 141 +/- 2.87 mmHg] for 15 s and 21% O(2) for 1 min 45 s, 60 cycles; B, severe IH group, 5% O(2) [PO(2) about 35.2 +/- 1.27 mmHg] 15 s and 21% O(2) 1 min 45 s, 60 cycles; C, mild IH group, 10% O(2) [PO(2) about 54.3 +/- 3.31 mmHg] 15 s and 21% O(2) 1 min 45 s, 60 cycles; D, severe IH+Lep group, protocol was the same with severe IH group; E, CH group, IN for 1 h 45 min and then 5% O(2) for 15 min; and F, Lep group, the same with IN group. Right common carotid artery parts distal to the cannula were harvested after exposure, and endothelial cell layers were gotten from longitudinal outspread vessels. Nuclear factor kappaB (NFkappaB) DNA binding activities of partial cell layers were measured with electrophoretic mobility shift assay in the IN group, severe IH group, mild IH group, and CH group nuclear extracts. The other part of the cell layers in the IN group, severe IH group, severe IH+Lep group, and Lep group were cultured for 2 h, and during the culture procedure, recombinated human leptin solutions were added to culture dishes of severe IH+Lep group and Lep group (resulted concentration, 10 ng/mL). Enzyme-linked immunosorbent assay was used to analyze medium interleukin-6 (IL-6) concentrations, reverse transcription polymerase chain reaction was used to analyze endothelial cell Ras homology A (RhoA) mRNA expression levels. Statistical analysis was done with SPSS 11.5 software package.

RESULTS

NFkappaB DNA binding activities were significantly different between groups (F = 112.428, P < 0.001). This activity in the severe IH group (4.27 +/- 0.64) was higher than that in the mild IH group (2.33 +/- 0.45, P < 0.001), IN group (1.00 +/- 0.26, P < 0.001), and CH group (1.15 +/- 0.36, P < 0.001). RhoA mRNA expression levels were different in groups (F = 26.634, P < 0.001).This level in the severe IH+Lep group (2.54 +/- 0.53) was higher than that in the severe IH group (1.57 +/- 0.44, P = 0.002), IN group (1.00 +/- 0.31, P < 0.001), and Lep group (1.31 +/- 0.30, P < 0.001). IL-6 concentrations were different in groups (F = 79.922, P < 0.001). IL-6 concentration in the severe IH+Lep group (1591.50 +/- 179.57 pg/mL) was higher than that in the severe IH group (1217.20 +/- 320.62 pg/mL, P = 0.036), IN group (325.40 +/- 85.26 pg/mL, P < 0.001), and Lep group (517.40 +/- 183.09 pg/mL, P < 0.001).

CONCLUSIONS

IH/ROX activated the inflammation pathway significantly in the endothelium, which was more intensive than CH and intensity-dependent. When exposed to both IH/ROX and leptin, inflammation occurs more dramatically. It means that synergic activating roles were performed by IH/ROX and leptin. This study may have a clinical implication that IH can cause endothelial damage through activated inflammation in OSA patients, and if the OSA patients have obesity at the same time, the endothelial damage or the inflammation would be more significant because of elevated leptin level as a synergic factor.

Administration of sesamol improved blood-brain barrier function in streptozotocin-induced diabetic rats

Uncontrolled or poorly controlled blood glucose during diabetes is an important factor in worsened vascular function. While evidence suggests that hyperglycemia-induced oxidative stress plays a prominent role in development of microangiopathy of the retina, kidney, and nerves, the role oxidative stress plays on blood-brain barrier (BBB) function and structure has lagged behind. In this study, a natural antioxidant, sesamol, was administered to streptozotocin (STZ)-induced diabetic rats to examine the role that oxidative stress plays on BBB structure and function. Experiments were conducted at 56 days after STZ injection. Male Sprague-Dawley rats randomly were divided into four treatment groups CON--control; STZ--STZ-induced diabetes; CON + S--control + sesamol; STZ + S--STZ-induced diabetes + sesamol. Functional and structural changes to the BBB were measured by in situ brain perfusion and western blot analysis of changes in tight junction protein expression. Oxidative stress markers were visualized by fluorescent confocal microscopy and assayed by spectrophotometric analysis. Results demonstrated that the increased BBB permeability observed in STZ-induced diabetic rats was attenuated in STZ + S rats to levels observed in CON. Sesamol treatment reduced the negative impact of STZ-induced diabetes on tight junction protein expression in isolated cerebral microvessels. Oxidative stress markers were elevated in STZ as compared to CON. STZ + S displayed an improved antioxidant capacity which led to a reduced expression of superoxide and peroxynitrite and reduced lipid peroxidation. In conclusion, this study showed that sesamol treatment enhanced antioxidant capacity of the diabetic brain and led to decreased perturbation of hyperglycemia-induced changes in BBB structure and function.