Sekaran Muniandy

Novel adiponectin-resistin (AR) and insulin resistance (IRAR) indexes are useful integrated diagnostic biomarkers for insulin resistance, type 2 diabetes and metabolic syndrome: a case control study

BackgroundAdiponectin and resistin are adipokines which modulate insulin action, energy, glucose and lipid homeostasis. Meta-analyses showed that hypoadiponectinemia and hyperresistinemia are strongly associated with increased risk of insulin resistance, type 2 diabetes (T2DM), metabolic syndrome (MS) and cardiovascular disease. The aim of this study was to propose a novel adiponectin-resistin (AR) index by taking into account both adiponectin and resistin levels to povide a better indicator of the metabolic homeostasis and metabolic disorders. In addition, a novel insulin resistance (IRAR) index was proposed by integration of the AR index into an existing insulin resistance index to provide an improved diagnostic biomarker of insulin sensitivity.MethodsIn this case control study, anthropometric clinical and metabolic parameters including fasting serum total adiponectin and resistin levels were determined in 809 Malaysian men (208 controls, 174 MS without T2DM, 171 T2DM without MS, 256 T2DM with MS) whose ages ranged between 40-70 years old. Significant differences in continuous variables among subject groups were confirmed by ANCOVA or MANCOVA test using 1,000 stratified bootstrap samples with bias corrected and accelerated (BCa) 95% CI. Spearmans rho rank correlation test was used to test the correlation between two variables.ResultsThe AR index was formulated as 1+log10(R0)-log10(A0). The AR index was more strongly associated with increased risk of T2DM and MS than hypoadiponectinemia and hyperresistinemia alone. The AR index was more strongly correlated with the insulin resistance indexes and key metabolic endpoints of T2DM and MS than adiponectin and resistin levels alone. The AR index was also correlated with a higher number of MS components than adiponectin and resistin levels alone. The IRAR index was formulated as log10(I0G0)+log10(I0G0)log10(R0/A0). The normal reference range of the IRAR index for insulin sensitive individuals was between 3.265 and 3.538. The minimum cut-off values of the IRAR index for insulin resistance assessment were between 3.538 and 3.955.ConclusionsThe novel AR and IRAR indexes are cost-effective, precise, reproducible and reliable integrated diagnostic biomarkers of insulin sensitivity for screening subjects with increased risk of future development of T2DM and MS.

F2-Isoprostanes as Novel Biomarkers for Type 2 Diabetes: a Review

Oxidative stress (OS) has been implicated as one of the major underlying mechanisms behind many acute and chronic diseases. However, the measurement of free radicals or their end products is complicated. Isoprostanes, derived from the non-enzymatic peroxidation of arachidonic acid are now considered to be reliable biomarkers of oxidant stress in the human body. Isoprostanes are involved in many of the human diseases such as type 2 diabetes. In type 2 diabetes elevated levels of F2-Isoprostanes (F2-IsoPs) have been observed. The measurement of bioactive F2-IsoPs levels offers a unique noninvasive analytical tool to study the role of free radicals in physiology, oxidative stress-related diseases, and acute or chronic inflammatory conditions. Measurement of oxidative stress by various other methods lacks specificity and sensitivity. This review aims to shed light on the implemention of F2-IsoPs measurement as a gold-standard biomarker of oxidative stress in type 2 diabetics.

Association of plasminogen activator inhibitor-1 and tissue plasminogen activator with type 2 diabetes and metabolic syndrome in Malaysian subjects

BackgroundIncreased plasma plasminogen activator inhibitor-1 (PAI-1) activity and decreased tissue plasminogen activator (tPA) activity could be considered a true component of the metabolic syndrome (MetS) associated with an increased risk of developing cardiovascular diseases (CVD) and fibrinolytic abnormalities. The aim of this study was to investigate the association of tPA and its inhibitor PAI-1 with type 2 diabetes (T2D) and MetS and interrelationship between PAI-1and tPA activities and antigens in Malaysian T2D and normal subjects.MethodsThe plasma activities and antigens of PAI-1 and tPA and the levels of the tPA/PAI-1 complex as well as serum insulin, parameter of the coronary risk panel and plasma glucose at fasting state were studied in 303 T2D subjects (227 with MetS and 76 without MetS), 131 normal non-diabetic non-metabolic subjects and 101 non-diabetic MetS subjects.ResultsThe PAI-1 activity was higher in subjects with T2D with MetS (P = 9.8 × 10-19) and non-diabetic subjects with MetS (P = 3.0 × 10-15), whereas the tPA activity was lower in T2D with MetS (P = 0.003) as compare to normal subjects. Plasma tPA antigen levels were higher in subjects with T2D with MetS (P = 8.9 × 10-24), T2D without MetS (P = 1.3 × 10-13) and non-diabetic MetS subjects (P = 0.002). The activity and antigen of PAI-1 in normal subjects were related to insulin resistance (P = 2.2 × 10-4; 0.007). Additionally, the PAI-1 activity was associated with an increased waist circumference (P = 2.2 × 10-4) and decreased HDL-c (P = 0.005), whereas the tPA activity was associated with decreased FBG (P = 0.028). The highest correlation was between PAI-1 activity and its antigen (R2 = 0.695, P = 1.1 × 10-36) in diabetic subjects. The tPA activity negatively correlated with its antigen (R2 = -0.444, P = 7.7 × 10-13) in normal subjects and with the PAI-1 activity and antigen (R2 = -0.319, P = 9.9 × 10-12; R2 = -0.228, P = 3.4 × 10-6) in diabetic subjects.ConclusionsPAI-1 and tPA activities and antigens were associated with diabetes and MetS parameters in Malaysian subjects.

Null association between ACE gene I/D polymorphism and diabetic nephropathy among multiethnic Malaysian subjects

BACKGROUND: Wide inter-ethnic allelic variations of the Angiotensin Converting Enzyme (ACE) i nsertion-deletion (I/D) gene polymorphism were thought to be responsible for the conflicting gene–diabetic nephropathy disease association worldwide. We have investigated the genetic susceptibility of the ACE gene to diabetic nephropathy in the multiethnic Malaysian population. MATERIALS AND METHODS: A total of 137 healthy (control) and 256 diabetic subjects were recruited. The diabetic subjects were further subdivided according to their nephropathy status based on urinary albumin-creatinine ratio (ACR) and glomerular filtration rate (GFR). Triple primer polymerase chain reaction (PCR) was used for ACE I/D genotyping. Subsequently, populationwide genetic analysis and gene-disease association studies were performed. RESULTS: The genotype frequencies in all subgroups were in Hardy-Weinberg equilibrium. Similar allelic and genotypic frequency of ACE I/D gene polymorphism was observed between healthy controls versus pooled type 2 diabetes mellitus (T2DM) subjects, and normoalbuminuria versus microalbuminuria, macroalbuminuria and End Stage Renal Failure (ESRF) (P > 0.05). Neither ethnicity nor gender exerted any influence on the ACE I/D gene polymorphism (P > 0.05), with the exception of the Chinese ethnic group which exhibited a higher frequency of ID genotype (P = 0.042). A multinomial logistic regression model showed that predictive factors including age, systolic blood pressure (SBP), high density lipoprotein (HDL) and glycosylated hemoglobin (HbA1C) were independently associated with diabetic nephropathy, in that order. CONCLUSION: The I/D polymorphism of the ACE gene is not significantly associated with both T2DM and/or diabetic nephropathy in this Malaysian population regardless of ethnicity and gender.

Role of Nε-(Carboxymethyl)Lysine in the Development of Ischemic Heart Disease in Type 2 Diabetes Mellitus

This study aims to determine the levels of Nε-(carboxymethyl)lysine (CML) in patients with Type 2 diabetic patients with and without ischemic heart disease (IHD) and to find for a possible association between circulating CML and a number of clinical parameters including lipids, hemoglobin A1c (HbA1c) and malondialdehyde (MDA) in Type 2 diabetic IHD patients. Serum CML levels were measured by enzyme-linked immunosorbent assay using polyclonal anti-CML antibodies. Serum levels of CML and MDA were assessed in 60 IHD patients with Type 2 diabetes, 43 IHD patients without Type 2 diabetes, 64 Type 2 diabetics without IHD, and 80 sex- and age-matched healthy subjects. Correlations studies between CML levels and lipids, HbA1c, and lipid peroxidation were performed in Type 2 diabetes patients with and without IHD. A statistical significance was observed in the levels of serum glucose, lipids (triglyceride, total cholesterol, HDL-cholesterol), MDA, HbA1c, CML and LDL-cholesterol (p<0.05) between the groups of the study. CML levels were significantly increased in diabetic IHD patients compared with Type 2 diabetes patients but without IHD (537.1 ± 86.1 vs 449.7 ± 54.9, p<0.001). A positive correlation was observed between serum levels of CML and MDA, r = 0.338 (p = 0.008) in Type 2 diabetes patients with IHD. However, age, HbA1c and lipids had no significant influence on CML levels among diabetics (p>0.05). In conclusion, this study demonstrates the effect of both diabetes and oxidative stress on the higher levels of circulating CML. These results showed that increased serum levels of CML are associated with the development of IHD in Type 2 diabetes mellitus.

Adiponectin and Resistin Gene Polymorphisms in Association with Their Respective Adipokine Levels

Single nucleotide polymorphisms (SNPs) at the adiponectin and resistin loci are strongly associated with hypoadiponectinemia and hyperresistinemia, which may eventually increase risk of insulin resistance, type 2 diabetes (T2DM), metabolic syndrome (MS), and cardiovascular disease. Real‐time PCR was used to genotype SNPs of the adiponectin (SNP+45T>G, SNP+276G>T, SNP+639T>C, and SNP+1212A>G) and resistin (SNP‐420C>G and SNP+299G>A) genes in 809 Malaysian men (208 controls, 174 MS without T2DM, 171 T2DM without MS, 256 T2DM with MS) whose ages ranged between 40 and 70 years old. The genotyping results for each SNP marker was verified by sequencing. The anthropometric clinical and metabolic parameters of subjects were recorded. None of these SNPs at the adiponectin and resistin loci were associated with T2DM and MS susceptibility in Malaysian men. SNP+45T>G, SNP+276G>T, and SNP+639T>C of the adiponectin gene did not influence circulating levels of adiponectin. However, the G‐allele of SNP+1212A>G at the adiponectin locus was marginally associated (P= 0.0227) with reduced circulating adiponectin levels. SNP‐420C>G (df = 2; F= 16.026; P= 1.50×10−7) and SNP+299G>A (df = 2; F= 22.944; P= 2.04×10−10) of the resistin gene were strongly associated with serum resistin levels. Thus, SNP‐420C>G and SNP+299G>A of the resistin gene are strongly associated with the risk of hyperresistinemia in Malaysian men.

The effect of relaxin on the musculoskeletal system

Relaxin is a hormone structurally related to insulin and insulin‐like growth factor, which exerts its regulatory effect on the musculoskeletal and other systems through binding to its receptor in various tissues, mediated by different signaling pathways. Relaxin alters the properties of cartilage and tendon by activating collagenase. This hormone is also involved in bone remodeling and healing of injured ligaments and skeletal muscle. In this review, we have summarized the literature on the effect of relaxin in musculoskeletal system to provide a broad perspective for future studies in this field.

Thrombophilia investigation in Malaysian women with recurrent pregnancy loss

Aim:  The status of thrombophilia in Asian women with recurrent pregnancy loss (RPL) is obscure and poorly understood. Numerous studies suggest the non‐existence or extreme rarity of the two important thrombophilia markers, factor V Leiden (FVL) and prothrombin G20210A (PTG) mutations, in patients of Asian ancestries. Thus, the consensus that thrombophilia is rare among Asians and laboratory investigations is irrelevant. We therefore investigated Malaysian women with RPL for thrombophilia abnormalities.

Sex-Steroid Regulation of Relaxin Receptor Isoforms (RXFP1 & RXFP2) Expression in the Patellar Tendon and Lateral Collateral Ligament of Female WKY Rats

The incidence of non-contact knee injury was found higher in female than in male and is related to the phases of the menstrual cycle. This raised the possibility that female sex-steroids are involved in the mechanism underlying this injury via affecting the expression of the receptors for relaxin, a peptide hormone known to modulate ligament laxity. Therefore, this study aims to investigate the effect of sex-steroids on relaxin receptor isoforms (RXFP1 & RXFP2) expression in the ligaments and tendons of the knee. Methods: Ovariectomized adult female WKY rats were treated with different doses of estrogen (0.2, 2, 20 μg/kg), progesterone (4mg) and testosterone (125 & 250μg/kg) for three consecutive days. At the end of the treatment, the animals were sacrificed and the patellar tendon and lateral collateral ligament were harvested for mRNA and protein expression analyses by Real Time PCR and Western blotting respectively. Results: RXFP1, the main isoform expressed in these knee structures and RXFP2 showed a dose-dependent increase in expression with estrogen. Progesterone treatment resulted in an increase while testosterone caused a dose-dependent decrease in the mRNA and protein expression of both relaxin receptor isoforms. Discussion: Progesterone and high dose estrogen up-regulate while testosterone down-regulates RXFP1 and RXFP2 expression in the patellar tendon and lateral collateral ligament of rats knee. Conclusion: Relaxin receptor isoforms up-regulation by progesterone and high dose estrogen could provide the basis for the reported increase in knee laxity while down-regulation of these receptor isoforms by testosterone could explain low incidence of non-contact knee injury in male.

In-vivo functional study on the involvement of CFTR, SLC26A6, NHE-1 and CA isoenzymes II and XII in uterine fluid pH, volume and electrolyte regulation in rats under different sex-steroid influence.

Precise control of uterine fluid pH, volume and electrolytes is important for the reproductive processes. In this study, we examined the functional involvement of multiple proteins including Cystic Fibrosis Transmembrane Regulator (CFTR), Cl-/HCO3- exchanger (SLC26A6), sodium-hydrogen exchanger-1 (NHE-1) and carbonic anhydrase (CA) in the regulation of these uterine fluid parameters. Methods: Adult female WKY rats were divided into intact, non-ovariectomised at different oestrous cycle phases and ovariectomised treated with sex-steroids. Following oestrous phase identification or sex-steroid treatment, in-vivo uterine perfusion was performed with and without the presence of these inhibitors: glibenclamide, DIDS, ACTZ and EIPA. The pH, volume, Cl-, HCO3- and Na+ concentrations of the perfusate from different groups were then analyzed. Meanwhile, the expression of CFTR, SLC26A6, NHE-1, CAII and CAXII was visualized by immunohistochemistry (IHC). Results: Parallel increase in the pH, volume, Cl-, HCO3- and Na+ concentrations was observed at estrus (Es), proestrus (Ps) and following 17β-oestradiol (E) treatment, which was inhibited by glibenclamide, DIDS and ACTZ while parallel reduction in these parameters was observed at diestrus (Ds) and following progesterone (P) treatment which was inhibited by ACTZ and EIPA. CFTR and SLC26A6 expression were up-regulated under E dominance, while NHE-1 expression was up-regulated under P dominance. Meanwhile, CA isoenzymes were expressed under both E and P influence. Conclusion: CFTR, SLC26A6 and CA were involved in mediating parallel increase in the uterine fluid volume, pH and electrolyte concentration under E while NHE and CA were involved in mediating the reduction of these parameters under P.