Hindlimb unweighting alters endothelium-dependent vasodilation and ecNOS expression in soleus arterioles.

The purpose of this study was to test the hypothesis that endothelium-dependent dilation is impaired in soleus resistance arteries from hindlimb-unweighted (HLU) rats. Male Sprague-Dawley rats (300-350 g) were exposed to HLU (n = 14) or weight-bearing control (Con, n = 14) conditions for 14 days. After the 14-day treatment period, soleus first-order (1A) arterioles were isolated and cannulated with micropipettes to assess vasodilator responses to an endothelium-dependent dilator, ACh (10(-9)-10(-4) M), and an endothelium-independent dilator, sodium nitroprusside (SNP, 10(-9)-10(-4) M). Arterioles from HLU rats were smaller than Con arterioles (maximal passive diameter = 140 +/- 4 and 121 +/- 4 microm in Con and HLU, respectively) but developed similar spontaneous myogenic tone (43 +/- 3 and 45 +/- 3% in Con and HLU, respectively). Arteries from Con and HLU rats dilated in response to increasing doses of ACh, but dilation was impaired in arterioles from HLU rats (P = 0.03), as was maximal dilation to ACh (85 +/- 4 and 65 +/- 4% possible dilation in Con and HLU, respectively). Inhibition of nitric oxide (NO) synthase (NOS) with N(omega)-nitro-L-arginine (300 microM) reduced ACh dilation by approximately 40% in arterioles from Con rats and eliminated dilation in arterioles from HLU rats. The cyclooxygenase inhibitor indomethacin (50 microM) did not significantly alter dilation to ACh in either group. Treatment with N(omega)-nitro-L-arginine + indomethacin eliminated all ACh dilation in Con and HLU rats. Dilation to sodium nitroprusside was not different between groups (P = 0.98). To determine whether HLU decreased expression of endothelial cell NOS (ecNOS), mRNA and protein levels were measured in single arterioles with RT-PCR and immunoblot analysis. The ecNOS mRNA and protein expression was significantly lower in arterioles from HLU rats than in Con arterioles (20 and 65%, respectively). Collectively, these data indicate that HLU impairs ACh dilation in soleus 1A arterioles, in part because of alterations in the NO pathway.     

Angiotensin-converting enzyme gene polymorphism is associated with type 2 diabetes: a meta-analysis

The association of angiotensin-converting enzyme gene polymorphism with type 2 diabetes was investigated in many studies with conflicting results. To clarify this conflict, we performed a meta-analysis on recent previous reports on ACE gene polymorphism and its correlation to type 2 diabetes. A total of 15,166 subjects from 24 studies were included in this meta-analysis. Summary odds ratios (ORs) were estimated. Potential sources of heterogeneity and bias were explored. The D variant was associated with a 14% increased risk of T2D relative to the I variant (OR 1.14; 95% CI: 1.04–1.24). In subgroup analysis, Caucasian and East Asians showed significant association. No association was found in the Turkish groups. No publication bias was observed in this meta-analysis by using the Egger method (τ = 1.63, P = 0.12), as well as the Begg’s test (z = 1.66, P = 0.10). Cumulative meta-analysis for the allelic contrast showed a trend of association as information accumulated. These data suggested that the variant of ACE I/D had a moderate positive association with type 2 diabetes.     

Circulating C5L2 gene polymorphism is associated with type 2 diabetes mellitus in Saudi population

The aim of the present study was to examine the relationship between the novel single nucleotide polymorphism, 698C>T that causes an amino acid change from proline to leucine at codon 233 and type 2 diabetes mellitus (T2DM) in the Saudi population. From the general population in the Saudi Arabia a total of 551 samples were collected and categorized them as T2DM (n = 376) and healthy controls (n = 175). Five ml of the blood sample was collected and used for the Biochemical and Molecular analysis. With the help of serum sample lipid profile: Fasting blood sugar (FBS), Total Cholesterol (TC), Triglycerides (TG), High Density Lipoprotein Cholesterol (HDL-C), Low Density Lipoprotein Cholesterol (LDL-C) and VLDL were performed. PCR–RFLP was performed after separating the genomic DNA from the EDTA blood. The genotype distribution of C698T polymorphism was performed by the Chi square test with SPSS version 16.0 software for comparing T2DM subjects and healthy controls. In our study, genotypic distributions of C5L2 C698T polymorphism and allele frequency of patients and controls were found to be significant difference in the allele and the genotypic distribution. [For T Vs C; p = 0.01; Odds ratio = 3.594 (95 % CI; 1.256–10.28); and CT+TT Vs CC; p = 0.009; Odds ratio = 3.707 (95 % CI; 1.285–10.69)]. TT genotype was completely absent in both the cases and the controls. In conclusion, our study indicates that 698C>T polymorphism of C5L2 gene is associated with the T2DM in individuals of Saudi population which was found to be similar with other studies.     

TRPV4 is involved in irisin-induced endothelium-dependent vasodilation

Irisin, an exercise-induced myokine, induces conversion of white into brown adipocytes, promoting mitochondrial biogenesis and energy expenditure. Irisin has a vascular protective effect on endothelial function in animals, including humans. Defects in irisin signaling pathways result in endothelial dysfunction in obesity and diabetes. However, the mechanisms underlying the effects of irisin on endothelial function have not been elucidated. Transient receptor potential vanilloid subtype 4 (TRPV4) channels are one of the most important Ca²⁺-permeable cation channels in vascular endothelial cells. In this study, we hypothesized that irisin may induce endothelium-dependent vasodilation by activating Ca²⁺ influx into endothelial cells via TRPV4 channels. In primary cultured rat mesenteric artery endothelial cells, irisin caused an increase in [Ca²⁺]_i due to extracellular Ca²⁺ influx rather than release from Ca²⁺ stores. Moreover, irisin-induced increases in [Ca²⁺]_i were completely abolished by a TRPV4 inhibitor. In addition, irisin induced endothelium-dependent vasodilation of rat mesenteric arteries. However, irisin had no effect on endothelium-independent vasodilation. Furthermore, irisin-induced vasodilation was fully abolished in the presence of a TRPV4 inhibitor, indicating the involvement of TRPV4 channels in endothelium-dependent vasodilation. This study provides the first evidence that irisin-induced endothelium-dependent vasodilation is related to the stimulation of extracellular Ca²⁺ influx via TRPV4 channels in rat mesenteric arteries.     

Independent case-control study in KCNJ11 gene polymorphism with Type 2 diabetes Mellitus

BackgroundType 2 Diabetes Mellitus (T2DM) is the most common form of diabetes in the aging population. This chronic metabolic disorder has discovered many candidate genes, and KCNJ11 was one of the genes associated with insulin secretion pathways mediated by potassium channels. There have been limited studies on the rs5210 polymorphism in T2DM patients, and none of them have been conducted in Saudi Arabia.AimThe aim of this study is to investigate at genotyping levels of rs5210 polymorphism in the KCNJ11 gene in older population with T2DM in the Saudi Population.MethodsBased on the sample size design, this case-control study included 102 T2DM cases and 102 controls. Using the PCR-RFLP assay, 204 patients extracted DNA was genotyped for the rs5210 polymorphism. SPSS software was used for statistical analysis, including t-tests, HWE, genotyping, and multiple logistic regression analysis.ResultsThe t-tests performed on T2DM cases and controls revealed a significant association in age, weight, BMI, FBG, Hb1Ac, SBP, DBP, HDLC, TC, and TG parameters (p < 0.05). HWE analysis found to be in consistent with rs5210 polymorphism. Allelic association was found in the rs5210 polymorphism (OR-1.64 [95 %CI: 1.08–2.49]; p = 0.01); however, no association (p > 0.05) was observed in the multivariate logistic regression assessment performed in this study.ConclusionThese results indicate that the rs5210 polymorphism was primarily associated with allele frequencies, which could be attributable to the small sample size. Large sample size studies will be required to determine whether KCNJ11 gene polymorphisms may be required as a risk marker for T2DM in the Saudi population.     

Interleukin-18 gene polymorphism,but not interleukin-2 gene polymorphism,is associated with rheumatoid arthritis

To investigate whether polymorphisms of IL-2 and IL-18 genes are associated with rheumatoid arthritis (RA), polymorphisms of IL-2 and IL-18 genes were detected by polymerase-chain-reaction-based restriction analysis in the patients with RA and normal controls. The results for the IL-18 gene revealed a significant difference between the patients and the normal controls (p = 0.000003), but there was no significant difference for the IL-2 gene (p = 0.876). The IL-18 gene 105A allele was associated with RA in Chinese patients. Individuals possessing the 105A allele had a higher incidence of RA. A lack of association of IL-2 gene polymorphism between RA patients and healthy individuals was noted. The results of this study provide genetic evidence that IL-18-105A/C polymorphism may play an effective role in RA.     

A visfatin promoter polymorphism is associated with low-grade inflammation and type 2 diabetes

Visfatin (also known as pre-B cell colony-enhancing factor, or PBEF) is a pro-inflammatory adipokine expressed predominantly in visceral fat. We investigated whether polymorphisms at the visfatin/PBEF locus influence the risk of type 2 diabetes (T2D). Linkage disequilibrium analysis of 52 single nucleotide polymorphisms spanning the entire gene (34.7 kb) plus 20.5 kb of the upstream region and 25.5 kb of the downstream region revealed a single haplotype block that could be tagged by seven single nucleotide polymorphisms. These seven tags were typed in a group of T2D patients (n = 814) and a group of non-diabetic controls (n = 320) of white origin. A significant association was observed at -948C>A, with minor allele frequencies of 0.157 in T2D cases and 0.119 in non-diabetic controls (p = 0.021). In a non-diabetic population (n = 630), the same -948 allele that conferred increased risk of T2D was significantly associated with higher plasma levels of fibrinogen and C-reactive protein (p = 0.0022 and 0.0038, respectively). However, no significant associations were observed with BMI, waist circumference, serum glucose levels, or fasting insulin levels. Our findings suggest that the visfatin/PBEF gene may play a role in determining T2D susceptibility, possibly by modulating chronic, low-grade inflammatory responses.     

The 223A>G polymorphism of the leptin receptor gene is associated with macroangiopathy in type 2 diabetes mellitus

To determine whether leptin receptor (LEPR) 223A>G polymorphism has an effect on the plasma leptin levels and the macroangiopathic complications in type 2 diabetes mellitus (T2DM). The genotypes and allelic frequencies of the LEPR 223A>G were examined with polymerase chain reaction and restriction fragment length polymorphism in 301 patients with T2DM and 172 unrelated healthy subjects. The plasma concentrations of leptin were determined in all subjects. The mean plasma leptin levels in the T2DM group were significantly higher than that of controls and the plasma levels of leptin were higher in diabetic patients with macroangiopathy than in patients without macroangiopathy (P < 0.05). The genotype (GG, AG and AA) distribution of 223A>G polymorphism was 58.3, 32.5, and 9.2% in diabetic patients with macroangiopathy, 75.3, 22.1, and 2.6% in patients without macroangiopathy, and 70.3, 27.5, 2.2% in controls respectively, a significant difference was found between diabetic patients with and without macroangiopathy (P < 0.05). The frequency of the allele A was higher in patients with macroangiopathy than in patients without macroangiopathy (25.6 vs. 16.3%; P < 0.05). Moreover, the plasma leptin levels were markedly higher in patients with AA genotype than those with AG or GG genotype in patients with macroangiopathy (P < 0.05). The LEPR 223A>G gene polymorphism associated with a predisposition to increased plasma leptin levels could constitute a useful predictive marker for diabetic macroangiopathy.     

Hindlimb unweighting decreases ecNOS gene expression and endothelium-dependent dilation in rat soleus feed arteries.

We tested the hypothesis that hindlimb unweighting (HLU) and the associated reduction in soleus muscle blood flow causes decreased expression of endothelial cell nitric oxide synthase (ecNOS) mRNA and protein and attenuated endothelium-dependent vasodilator responses in rat soleus feed arteries (SFA). Male Sprague-Dawley rats were exposed to HLU (n = 12) or cage control (Con; n = 12) conditions for 14 days. At the end of this period, SFA were isolated, removed, and cannulated with two glass micropipettes for examination of vasodilator responses or frozen for analysis of ecNOS mRNA and protein expression. RT-PCR of RNA from single SFA was used to measure ecNOS mRNA, and immunoblots on single SFAs were used to measure ecNOS protein content. Results revealed that both ecNOS mRNA and ecNOS protein expression were lower in SFA from HLU rats. Dilation to increased intraluminal flow was attenuated in SFA from HLU rats (Con: 88 +/- 8% vs. HLU: 53 +/- 8%) as was maximal vasodilation to acetylcholine (10(-9)-10(-4) M; Con: 88 +/- 5% vs. HLU: 73 +/- 5%). Sensitivity to the endothelium-independent vasodilator sodium nitroprusside (10(-10)-10(-4) M) was enhanced by HLU (EC(50): Con: 4.46 x 10(-7) M vs. HLU: 5.00 x 10(-8) M). Collectively, these data indicate that the chronic reduction in soleus blood flow associated with the reduced physical activity during HLU results in reduced expression of ecNOS mRNA and protein in SFA and attenuated endothelium-dependent vasodilation.     

The HHEX rs1111875A/G gene polymorphism is associated with susceptibility to type 2 diabetes in the iranian population

The illuminating picture of genetic mechanisms underlying the development of type 2 diabetes (T2DM) includes differently accumulated genetic polymorphisms that increase the risk along with environmental factors. A number of single nucleotide polymorphisms (SNPs) are indicated to be linked with T2DM, but also conflicting results have been found. To examine the contribution of these polymorphisms in conferring susceptibility to T2DM, the association of HHEX rs1111875A/G and CDKN2A/B rs10811661C/T common gene polymorphisms with the risk of T2DM in an Iranian population was evaluated. In this study participated 140 patients and 140 controls. Genomic DNA was extracted from samples and genotyping of the polymorphisms was performed by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique. A significant association was found with the G allele (OR = 1.729, CI = 1.184–2.523, P = 0.004) and GG genotype (OR = 2.921, 95% CI = 1.789–4.771, P< 0.001) of the rs1111875A/G SNP for susceptibility to T2DM in the recessive model. Furthermore, compared with the GG genotype, individuals with the GA genotype had a lower risk to develop T2DM (OR = 0.237, 95% CI = 0.137–0.408, P< 0.001) in the additive model. In addition, an association between the polymorphism and BMI in regard to the risk of T2DM was identified. The genotype and allele frequencies of the rs10811661C/T polymorphism did not show a statistically significant association with T2DM in any genetic model. Our results show that the rs1111875A/G polymorphism is an important susceptibility polymorphism for the development of T2DM in the Iranian population. Also, these findings support that this polymorphism is a key genetic risk factor for the development of T2DM in multiple ethnic populations.

     

Type 2 diabetes is associated with reduced ATP-binding cassette transporter A1 gene expression, protein and function

Objective

Increasing plasma glucose levels are associated with increasing risk of vascular disease. We tested the hypothesis that there is a glycaemia-mediated impairment of reverse cholesterol transport (RCT). We studied the influence of plasma glucose on expression and function of a key mediator in RCT, the ATP binding cassette transporter-A1 (ABCA1) and expression of its regulators, liver X receptor-α (LXRα) and peroxisome proliferator-activated receptor–γ (PPARγ).

Methods and Results

Leukocyte ABCA1, LXRα and PPARγ expression was measured by polymerase chain reaction in 63 men with varying degrees of glucose homeostasis. ABCA1 protein concentrations were measured in leukocytes. In a sub-group of 25 men, ABCA1 function was quantified as apolipoprotein-A1-mediated cholesterol efflux from 2–3 week cultured skin fibroblasts. Leukocyte ABCA1 expression correlated negatively with circulating HbA1c and glucose (rho = −0.41, p<0.001; rho = −0.34, p = 0.006 respectively) and was reduced in Type 2 diabetes (T2DM) (p = 0.03). Leukocyte ABCA1 protein was lower in T2DM (p = 0.03) and positively associated with plasma HDL cholesterol (HDL-C) (rho = 0.34, p = 0.02). Apolipoprotein-A1-mediated cholesterol efflux correlated negatively with fasting glucose (rho = −0.50, p = 0.01) and positively with HDL-C (rho = 0.41, p = 0.02). It was reduced in T2DM compared with controls (p = 0.04). These relationships were independent of LXRα and PPARγ expression.

Conclusions

ABCA1 expression and protein concentrations in leukocytes, as well as function in cultured skin fibroblasts, are reduced in T2DM. ABCA1 protein concentration and function are associated with HDL-C levels. These findings indicate a glycaemia- related, persistent disruption of a key component of RCT.     

Delayed threshold for active cutaneous vasodilation in patients with Type 2 diabetes mellitus.

Epidemiological evidence suggests decreased heat tolerance in patients with Type 2 diabetes mellitus (T2DM), but it is not known whether the mechanisms involved in thermoregulatory control of skin blood flow are altered in these patients. We tested the hypothesis that individuals with T2DM have a delayed internal temperature threshold for active cutaneous vasodilation during whole body heating compared with healthy control subjects. We measured skin blood flow using laser-Doppler flowmetry (LDF), internal temperature (T or) via sublingual thermocouple, and mean arterial pressure via Finometer at baseline and during whole body heating in 9 T2DM patients and 10 control subjects of similar age, height, and weight. At one LDF site, sympathetic noradrenergic neurotransmission was blocked by local pretreatment with bretylium tosylate (BT) to isolate the cutaneous active vasodilator system. Whole body heating was conducted using a water-perfused suit. There were no differences in preheating T(or) between groups (P > 0.10). Patients with T2DM exhibited an increased internal temperature threshold for the onset of vasodilation at both untreated and BT-treated sites. At BT-treated sites, T or thresholds were 36.28 +/- 0.07 degrees C in controls and 36.55 +/- 0.05 degrees C in T2DM patients (P < 0.05), indicating delayed onset of active vasodilation in patients. Sensitivity of vasodilation was variable in both groups, with no consistent difference between groups (P > 0.05). We conclude that altered control of active cutaneous vasodilation may contribute to impaired thermoregulation in patients with T2DM.     

The ESR2 AluI gene polymorphism is associated with bone mineral density in postmenopausal women

Multiple factors may contribute to the pathogenesis of postmenopausal osteoporosis including environmental, life-style and genetic factors. Common variants in ESR2 gene encoding for ER-beta, highly expressed in bone tissue, have recently been proposed as candidates for affecting bone phenotype at the population level, particularly in postmenopausal women. In this study, we examined the genetic background at ESR2 AluI (rs4986938, 1730G>A) locus in 89 osteopenic, postmenopausal women (age range 49-56 years) together with BMD at lumbar spine and femoral neck sites as well as variations in plasma levels of bone metabolism and turnover markers. Genotyping for ESR2 G1730A polymorphism showed that the frequency of A mutated allele accounted for 0.4 in our cohort of postmenopausal women; moreover, the GA1730 heterozygous individuals were the most represented (50.6%) compared with GG (37.8%) and AA homozygous ones (14.6%). A regression analysis showed that lumbar spine BMD values were significantly associated with both ESR2 AA1730 genotype (p=0.044) and time since the onset of menopause (p=0.031), while no significant association was detected between biochemical markers and genetic background. Interestingly, 85% of patients with AA1730 genotype presented the smallest lumbar spine BMD values. These findings first indicate a worsening effect of ESR2 AluI polymorphism on lumbar spine BMD reduction in postmenopause, suggesting that the detection of this ESR2 variant should be recommended in postmenopausal women, particularly in populations with a high prevalence of ESR2 AA1730 homozygous genotype.     

Vitamin D receptor gene polymorphism is associated with chronic periodontitis

Chronic periodontitis (CP) is caused by enhanced resorption of the alveolar bone supporting the teeth and is associated with intraoral inflammation after infection with certain bacteria. The VDR gene polymorphism was reported recently to be deeply related to the occurrence of tuberculosis and infection of chronic hepatitis B virus. This may be interpreted to indicate a close relationship between VDR gene polymorphism and the immunological action, because vitamin D activates monocytes, stimulates cell-mediated immunity, and suppresses lymphocyte proliferation. The purpose of the present study was to clarify whether polymorphisms in VDR gene exons are associated with the incidence of CP. A case-controlled study was performed on a group of 168 unrelated Japanese subjects whose ages ranged from 35 to 65 years. The Taq I polymorphism in the VDR gene was found to be associated significantly with CP (X2=4.48, P=0.034). We performed multiple logistic regression analyses on the TT genotype, which was found to be associated with CP, and on well-recognized risk factors, smoking and diabetes. The odds ratio (OR) for the genotype (TT/Tt) was 2.73 (95% CI 1.11-6.68, P=0.028), being larger than the unadjusted value. This indicates that the VDR gene polymorphism (TT genotype) is a risk factor for CP, independently of smoking and diabetes.     

A polymorphism in <Emphasis Type="Italic">PTPN2</Emphasis> gene is associated with an earlier onset of type 1 diabetes

The Wellcome Trust Case Control Consortium (WTCCC) genome-wide study found association of PTPN2 with three autoimmune diseases, among them is type 1 diabetes (T1D). This result was confirmed by a follow-up study that pointed to new independent signals within the region. However, both studies were performed in patients with an early-onset T1D. We aimed at replicating the previous results and studying the influence of these polymorphisms in the age at T1D debut. We genotyped 439 T1D Spanish subjects (age at onset, 1 to 65 years) and 861 controls for two PTPN2 single nucleotide polymorphisms (SNPs), rs2542151 and rs478582, and studied the effect of both polymorphisms in age at onset through stratified and continuous analyses. The frequency of rs2542151*G carriers was significantly higher in the early-onset group compared with late-onset patients (p = 0.023) and with controls (OR = 1.61 [1.14–2.26]; p = 0.005). No significant differences were found between controls and late-onset patients. The log-rank chi-square test for the Kaplan–Meier plots (carriers of susceptibility allele vs non carriers) was statistically significant (χ _1df² = 4.485; p = 0.034), yielding an earlier disease debut for G carriers. The analysis of the SNP rs478582 did not reach statistical significance. In summary, we replicate the association detected by the WTCCC and propose that the rs2542151*G allele confers risk to an earlier onset of T1D.     

A resistin gene polymorphism is associated with body mass index in women

The potential association of resistin (RETN) gene variability with obesity-related phenotypes was investigated in 585 non-diabetic individuals of European descent. The polymorphism studied (–420 C>G) is located in the RETN gene 5-flanking region. A significant association between the polymorphism and body mass index and waist circumference was observed in the women subsample (n=356), where the G allele was somewhat less frequent in the overweight/obese group than in normal-weight individuals (0.25 vs. 0.32; p=0.040; OR=0.70 [0.50–0.98]). Female carriers of the G-allele presented a lower mean BMI than C/C homozygotes (25.5 vs. 26.8 kg/m²; p=0.010). Furthermore, when women were stratified by menopausal status, the association was restricted to premenopausal women (C/C homozygotes, mean BMI=26.3 kg/m²; G-carriers, 24.4 kg/m²; p=0.014). Our findings suggest that RETN gene variation has gender-specific effects on BMI and warrants further investigation of its implications for the development of obesity.