Okan Dikker

Evaluation of the Relation Between Omentin-1 and Vitamin D in Postmenopausal Women With or Without Osteoporosis

INTRODUCTION Crosstalk between bone and adipose tissues is implicated in several pathologic conditions related to bone metabolism. Omentin-1, a 34-kD protein, is released from omental adipose tissue. A few studies indicated the effect of omentin-1 on bone health and bone mineral density (BMD) and the interaction of omentin-1 with vitamin D. Therefore, this study aimed to investigate the relationship between omentin-1, vitamin D, and BMD in postmenopausal women with osteoporosis compared with non-osteoporotic counterparts. MATERIALS AND METHODS Forty postmenopausal women with osteoporosis (OP), 40 counterparts without OP, and 30 premenopausal women were enrolled. Dual-energy X-ray Absorptiometry results, body mass index, and some demographic and biochemical data were recorded. Vitamin D (25-hydroxyvitamin D3) levels were measured using liquid chromatography-tandem mass spectrometry. Serum omentin-1 was determined using an enzyme-linked immunosorbent assay. RESULTS Omentin-1 levels tended to increase in both postmenopausal women groups compared with the control group, but this increase was significant only in women with osteoporosis. Vitamin D levels were not different between the groups. When women were categorized according to vitamin D levels, women with normal vitamin D levels had significantly higher omentin-1 levels. A positive correlation was found between omentin-1 and vitamin D levels in all groups (r=0.197, p=0.041, n=110). CONCLUSION The tendency to an increase in omentin-1 levels in postmenopausal women with osteoporosis may be due to a physiologic compensation against bone loss after menopause. The linear relationship between omentin-1 and vitamin D suggests that adipose tissue is one of the target tissues for the vitamin D effect.

Serum Angiopoietin-like peptide 4 levels in patients with hepatic steatosis

Objectives Angiopoietin‐like peptide 4 (ANGPTL‐4) plays an important role in lipid metabolism by inhibiting the enzyme lipoprotein lipase. This effect of ANGPTL‐4 results in suppression of the release of plasma triglyceride‐derived fatty acids. Increase in fatty acid levels entering to the liver and abnormalities in their secretion is one of the main mechanisms in pathogenesis of hepatic steatosis. In this study, we aimed to investigate the role of ANGPTL‐4 in pathogenesis of hepatic steatosis by determining its levels in patients with fatty liver disease. Methods Totally 51 patients (age: 37.9 ± 9.9 years, M/F) diagnosed with grade 2–3 hepatic steatosis with ultrasound and 30 healthy volunteers (age: 34.8 ± 9.5 years, M/F) were included in the study. In both groups, routine biochemical tests including fasting blood glucose, fasting insulin levels, triglyceride, total cholesterol, LDL‐ cholesterol, HDL‐cholesterol, AST, ALT, ALP, GGT levels were measured together with the ANGPTL‐4 levels. In determination of ANGPTL‐4 levels, ELISA was performed. Results When compared with the control group, ANGPTL‐4 levels were determined to be decreased in patients with hepatic steatosis (369 ± 243 vs 303 ± 286 ng/mL, p = 0.014). There was a negative weak correlation observed between ANGPTL‐4 and triglyceride levels (r = −0.246, p = 0.027). Among all groups, when patients with and without insulin resistance were compared; ANGPTL‐4 levels were determined to be similar. While fasting blood glucose levels were similar between 2 groups; fasting insulin and triglyceride levels were determined to be increased in hepatic steatosis group (Insulin 17.7 ± 12 vs 7.4 ± 3.3 &mgr;IU/mL, p < 0.001, triglyceride 158 ± 46.4 vs 118 ± 59.8 mg/dL p < 0.001). Conclusions We have determined lower serum ANGPTL‐4 levels in patients with hepatic steatosis. ANGPTL‐4 that is regulating LPL activity plays an important role in fatty liver disease pathogenesis via free fatty acid metabolism and peroxisome proliferator‐activated receptor‐delta (PPAR‐&dgr;). We believe that the results of this study would elucidate the investigations about the mechanism of fatty liver disease development and treatments targeting ANGPTL‐4. HighlightsThis is the first study evaluating Angiopoietin‐like peptide 4 (ANGPTL‐4) in hepatic steatosis.Angiopoietin‐like peptide 4 (ANGPTL‐4) level decreases in hepatosteatosis.ANGPTL‐4 probably acts via free fatty acid metabolism and PPAR‐&dgr;.

The Effects of Blood Glucose Regulation in Omentin-1 Levels among Diabetic Patients

Objectives: Omentin-1, an adipocytokine that increases the insulin sensitivity, has been determined to be reduced in patients with insulin resistance, impaired glucose tolerance, and Type-2 diabetes mellitus. In this study, we have investigated the alterations in Omentin-1 levels with the blood glucose regulation in diabetic patients having poor glycemic control. By this way, we aimed to determine the role of Omentin-1 as a marker in follow-up and monitoring progression of diabetes. Methods: Totally 58 patients with type 2 diabetes mellitus, older than 18 years of age who were having poor glycemic control (HbA1c≥9) were included in this study. In the first visit, all clinical and biochemical parameters of patients were recorded. After baseline evaluation, the patients were advised life style changes, and their medical treatment was determined individually according to the recommendations of the American Diabetes Association guidelines. At the end of the third month patients were re-evaluated. Serum Omentin-1 levels were measured with ELISA. Results: In patients using only oral antidiabetic agents, after exchanging the treatment with insulin, on 3rd month of treatment, there was a significant decrease in serum C-peptide and Omentin-1 levels compared with the initial results (p=0.034, p=0.048, respectively). On the other hand, in patients using insulin treatment from the beginning of the study, there was not any significant alterations in serum C-peptide or Omentin-1 levels compared with the initial results (p>0.05). Conclusions: Serum Omentin-1 levels may change with insulin and metformin treatments in Type-2 diabetic patients. In patients with poor glycemic control, Omentin-1 levels do not change with the regulation of blood glucose levels. A decrease in Omentin-1 and C-peptide levels has been determined after the initiation of insulin therapy. This suggests that, Omentin-1 levels are closely associated with the endogenous insulin reserve and may be used in follow-up of patients.