Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Leptin is produced in adipose tissue and acts in the hypothalamus to regulate food intake. However, recent evidence also indicates a potential for direct roles for leptin in peripheral tissues, including those of the immune system. In this study, we provide direct evidence that macrophages are a target tissue for leptin. We found that J774.2 macrophages express the functional long form of the leptin receptor (ObRb) and that this becomes tyrosine-phosphorylated after stimulation with low doses of leptin. Leptin also stimulates both phosphoinositide 3-kinase (PI 3-kinase) activity and tyrosine phosphorylation of JAK2 and STAT3 in these cells. We investigated the effects of leptin on hormone-sensitive lipase (HSL), which acts as a neutral cholesterol esterase in macrophages and is a rate-limiting step in cholesterol ester breakdown. Leptin significantly increased HSL activity in J774.2 macrophages, and these effects were additive with the effects of cAMP and were blocked by PI 3-kinase inhibitors. Conversely, insulin inhibited HSL in macrophages, but unlike adipocytes, this effect did not require PI 3-kinase. These results indicate that leptin and insulin regulate cholesterol-ester homeostasis in macrophages and, therefore, defects in this process caused by leptin and/or insulin resistance could contribute to the increased incidence of atherosclerosis found associated with obesity and type 2 diabetes.
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PMID:Insulin and leptin acutely regulate cholesterol ester metabolism in macrophages by novel signaling pathways. 1133 38

Plasma leptin concentration is closely associated with body fat in humans, with energy restriction inducing a greater decrease in plasma leptin than in body fat. Since adequate energy restriction is mandatory in diet therapy of diabetes mellitus especially in obese subjects, the present study was undertaken to evaluate the clinical implication of serial leptin measurement in the management of diabetic patients. Fifty-four consecutive subjects with type 2 diabetes, who were subjected to adjusted energy restriction during hospitalization, were enrolled in the study. During their hospitalization period (24+/-4 days), plasma leptin concentrations decreased from 6.9+/-0.7 to 5.7+/-0.6 microg/l (P<0.0001) in the overall subjects, and the %change in plasma leptin (-13.9%) was greater than the %changes in body mass index (BMI) and percent body fat (-1.7% and -4.7%, respectively). The %change in plasma leptin was positively correlated with the %changes in BMI and plasma C-peptide (r=0.526, P<0.0001 and r=0.446, P<0.002, respectively) and negatively with a %change in plasma ketone bodies (r=-0.516, P<0.005). Multiple regression analysis revealed that the %changes in BMI and plasma C-peptide were independent determinants of the %change in plasma leptin. In addition, 38 subjects were followed up after discharge. Three months after discharge, plasma leptin concentrations significantly increased by 25.6%, which was again much greater than the %change in BMI (+0.9%). In 28 subjects who showed increase in plasma leptin levels after discharge, BMI was also increased. In contrast, the remaining 10 subjects without the increase in plasma leptin kept their BMI unchanged. Throughout the observation period, the changes in plasma leptin were prominent in the subjects with BMI greater than 25 kg/m2. In conclusion, plasma leptin concentrations showed greater changes than the alterations in anthropometric indexes during the observation period. Serial leptin measurement may be useful to estimate adherence to energy restriction especially in obese subjects with type 2 diabetes.
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PMID:Clinical implication of serial leptin measurement in subjects with type 2 diabetes mellitus. 1140 7

It is not known whether obesity increases the risk for hepatocellular carcinoma (HCC) simply because it promotes cirrhosis, a general risk factor for HCC, or via some other mechanism that operates independently of cirrhosis. If the latter occurs, then hepatocyte hyperplasia, an early event during the neoplastic process, might begin before liver cirrhosis develops. Genetically obese, leptin-deficient ob/ob mice are models for nonalcoholic fatty liver disease (NAFLD), a type of liver disease that is strongly associated with obesity and type 2 diabetes. Similar to obese, diabetic patients, ob/ob mice have an increased incidence of HCC. However, unlike humans with NAFLD, they rarely, if ever, develop cirrhosis spontaneously. To determine whether the noncirrhotic livers of ob/ob mice with NAFLD exhibit hepatocyte hyperplasia, parameters of proliferation and apoptosis were compared in adult ob/ob mice and their healthy litter mates. Adult ob/ob mice have an increase in liver mass relative to body mass. This hepatomegaly cannot be explained solely by lipid accumulation and is accompanied by significant increases in hepatocyte proliferative activity (as evidenced by increased Erk activation, cell-cycle related gene expression, bromodeoxyuridine incorporation, and hepatic DNA content) with concomitant inhibition of hepatocyte apoptosis (as evidenced by decreased numbers of apoptotic hepatocytes, induction of several antiapoptotic mechanisms, and decreased activation of procaspase 3). Thus, liver hyperplasia is evident at the earliest stage of NAFLD in ob/ob mice, which supports the concept that obesity-related metabolic abnormalities, rather than cirrhosis, initiate the hepatic neoplastic process during obesity.
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PMID:Hepatic hyperplasia in noncirrhotic fatty livers: is obesity-related hepatic steatosis a premalignant condition? 1143 35

Mutations in the melanocortin 4 receptor gene (MC4R) are the most common cause of monogenic human obesity. As part of our ongoing project entitled 'Turkish Obesity Genome Study' we determined the nucleotide sequence of the entire coding region of the MC4R gene in 40 morbidly obese subjects from independent families. Here we report a novel heterozygous mutation (N274S) in an adult female obese individual (age: 52 yrs, BMI 41.7 kg/m(2), height 158 cm, weight: 104 Kg). The sister of the index case (age: 55 yrs, height: 160 cm, weight: 110 Kg, BMI: 43 kg/m(2)) also carries the same mutation. Although both sisters were morbidly obese and hypertensive the index case had normal plasma insulin and fasting blood glucose levels whereas her sister had type 2 diabetes mellitus. No abnormalities of the reproductive function were present. Despite marked hyperphagia in childhood both sisters had a history of relatively diminished intensity of appetite after the age of 20. Of notice, index case was diagnosed to have cyclothymia whereas her sister was being treated for bipolar affective disorder. Detailed clinical evaluation revealed normal bone mineral density and serum calcium parameters as well as intact thyroid axis and hypothalamus-pituitary-adrenal axis in both patients. The human MC4-R deficient phenotype resembles the murine deficient state with regard to preserved reproductive function although hyperphagia, increased linear growth and absence of diabetes in mice are not observed in humans. Affected individuals have hyperphagia in childhood, which looses intensity later in life, and they also present with normal height and diabetes mellitus. Accumulating evidence indicate that melanocortin endocrine system or defective melanocortin signaling has inherently different characteristics in mice and humans resembling the variation observed with regard to leptin deficiency in both species.
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PMID:A novel melanocortin 4 receptor (MC4R) gene mutation associated with morbid obesity. 1144 23

Localized lesions at the foot skeleton are a serious and well recognized complication of diabetes mellitus which may impair the clinical outcome of the patients remarkably. In contrast, the presence of a generalized bone disease or osteoporosis related to diabetes mellitus is less acknowledged and its clinical relevance is less obvious. This paper is a clinically focused review of the literature on osteoporosis related to diabetes mellitus. Due to the different pathogenesis of diabetes mellitus type 1 and type 2 it is not surprising that there is no uniform entity of diabetic osteopathy. The majority of clinical studies in subjects with diabetes mellitus type 1 showed a moderately decreased bone mass at the forearm, while bone mass at the femur or lumbar spine was either decreased or not different from non-diabetic controls. In patients with diabetes mellitus type 2 the risk of osteopenia is not as clear as in type 1 diabetes. Bone mineral density at the forearm in patients with type 2 diabetes mellitus was decreased, unchanged or even increased in comparison to controls, while bone mineral density at the vertebrae or femoral neck was either not significantly different or increased, but rarely decreased. The underlying mechanisms triggering changes in bone mass in patients with diabetes mellitus type 1 and type 2 are not well known. In most studies there was no consistent relationship between the metabolic control of diabetes and bone mineral density. Biochemical parameters of the calcium and bone metabolism showed no clear relationship to the bone mineral density measurements. From few bone histology studies in humans and experimental studies there is evidence that a decreased bone formation is one major mechanism leading to reduced bone mass in diabetics. Microangiopathy at the bone tissue was also discussed as a possible reason for diabetic osteopenia. It was shown that insulin and insulin like growth factors (IGF-1, IGF-2) have an influence on bone metabolism itself and other growth factors, cytokines and hormones may determine changes in diabetic bone metabolism. Recent findings suggest that leptin is involved in the regulation of osteoblast function and bone mass, which is of special interest in diabetes mellitus type 2. The clinical relevance of osteoporosis or osteopenia is determined by the increased risk for insufficiency fractures. Few studies found an increased fracture risk, especially in older women with type 1 diabetes mellitus, while others did not show an increased risk for fractures or even found a decreased rate of fractures in women with diabetes mellitus type 2. There is a need for further longitudinal studies, including the incidence and risk factors for osteoporotic fractures. In clinical routine the extent of diagnostic and therapeutic activities in patients with type 1 or type 2 diabetes mellitus in respect to generalized bone disease or diabetic osteopenia should be based on individual conditions and risk profile for osteoporosis.
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PMID:Diabetes mellitus a risk for osteoporosis? 1146 May 94

Patients with insulin resistance and/or type 2 diabetes have a 5-fold increase in cardiovascular mortality rate. Therefore, it is a current issue of discussion that arterial hypertension, lipid disorders as well as visceral obesity are coronary risk factors, which might belong to a syndrome that is caused by decreased insulin sensitivity. Concerning a possible molecular link between insulin resistance, atherosclerosis and obesity, we focus in our research on questions looking for a molecular link between lipid metabolism, insulin action, and obesity at a gene regulatory level. Alterations in the structure, function and regulation of transcription factors appear to be such signalling steps which might play an essential role in the pathogenesis and therapy of cardiovascular risk factors associated with insulin resistance, eg the so called metabolic syndrome. Recent examples are members of the nuclear hormone receptor superfamily, eg peroxisome proliferator-activated receptor (PPAR) isoforms and sterol regulatory element-binding proteins (SREBPs). Beside their regulation by different metabolites, these transcription factors are also targets of hormones, like insulin and leptin, growth factors, and inflammatory signals. Therefore, they appear to be a point of signalling convergence at a gene regulatory level. Major signalling pathways coupling receptors at the cell surface for hormones, growth factors as well as cytokines to gene regulatory events in the nucleus are the MAP-kinase cascades. We have recently defined different postreceptor defects in these pathways in patients with clinical phenotypes corresponding to congenital lipoatrophy. Therefore, these studies may identify novel pathways which play a role in the control of body weight, insulin sensitivity and cardiovascular risk.
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PMID:Insulin-regulated transcription factors: molecular link between insulin resistance and cardiovascular risk factors. 1146 84

The enzyme glucokinase (GK) plays a central role in glucose homeostasis. Hepatic GK activity is acutely controlled by the action of the GK regulatory protein (GKRP). In vitro evidence suggests that GKRP reversibly binds to GK and inhibits its activity; however, less is known about the in vivo function of GKRP. To further explore the physiological role of GKRP in vivo, we used an E1/E2a/E3-deficient adenoviral vector containing the cDNA encoding human GKRP (Av3hGKRP). High fat diet-induced diabetic mice were administered Av3hGKRP or a control vector lacking a transgene (Av3Null). Surprisingly, the Av3hGKRP-treated mice showed a significant improvement in glucose tolerance and had lower fasting blood glucose levels than Av3Null-treated mice. A coincident decrease in insulin levels indicated that the Av3hGKRP-treated mice had sharply improved insulin sensitivity. These mice also exhibited lower leptin levels, reduced body weight, and decreased liver GK activity. In vitro experiments indicated that GKRP was able to increase both GK protein and enzymatic activity levels, suggesting that another role for GKRP is to stabilize and/or protect GK. These data are the first to indicate the ability of GKRP to treat type 2 diabetes and therefore have significant implications for future therapies of this disease.
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PMID:Treatment of type 2 diabetes by adenoviral-mediated overexpression of the glucokinase regulatory protein. 1147 43

Adiponectin is an adipocyte-derived hormone. Recent genome-wide scans have mapped a susceptibility locus for type 2 diabetes and metabolic syndrome to chromosome 3q27, where the gene encoding adiponectin is located. Here we show that decreased expression of adiponectin correlates with insulin resistance in mouse models of altered insulin sensitivity. Adiponectin decreases insulin resistance by decreasing triglyceride content in muscle and liver in obese mice. This effect results from increased expression of molecules involved in both fatty-acid combustion and energy dissipation in muscle. Moreover, insulin resistance in lipoatrophic mice was completely reversed by the combination of physiological doses of adiponectin and leptin, but only partially by either adiponectin or leptin alone. We conclude that decreased adiponectin is implicated in the development of insulin resistance in mouse models of both obesity and lipoatrophy. These data also indicate that the replenishment of adiponectin might provide a novel treatment modality for insulin resistance and type 2 diabetes.
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PMID:The fat-derived hormone adiponectin reverses insulin resistance associated with both lipoatrophy and obesity. 1147 13

Troglitazone is effective in approximately 50% in patients with type 2 diabetes (NIDDM). In this study, we investigated the relations between serum leptin levels and clinical efficacy of troglitazone. Forty-five type 2 diabetic patients (23 men and 22 women) from our outpatient clinic were treated with troglitazone 400 mg daily for 12 weeks. Fasting plasma glucose (FPG), HbA1c, body weight, serum insulin and leptin concentrations were measured before and after troglitazone treatment. After 12 weeks of troglitazone treatment, FPG (before versus after, 179+/-33 vs. 138+/-26 mg/dl, mean+/-SD), HbA1c (7.8+/-1.3 vs. 6.9+/-1.0%), IRI (8.3+/-4.3 vs. 6.3+/-3.4 microU/ml) and HOMA-R index (homeostasis model assessment of insulin resistance) (3.8+/-2.4 vs. 2.2+/-1.3) decreased significantly, while body mass index (BMI) slightly increased (26.3+/-3.5 vs. 26.6+/- 3.6 kg/m(2)), and serum leptin remained unchanged (8.5+/-7.2 vs. 9.1+/-8.7 ng/ml). Reduction in FPG (DeltaFPG) after troglitazone treatment were correlated with reduction in HOMA-R (DeltaHOMA-R) (r=0.721, P<0.0001). DeltaFPG was correlated with serum leptin (r=0.441, P<0.01), HOMA-R (r=0.460, P<0.01) and FPG (r=-0.781, P<0.0001) at baseline, but not with BMI and serum IRI at baseline. Furthermore, serum leptin at baseline was significantly correlated with DeltaHOMA-R (r=0.634, P<0.01). Leptin concentration before treatment therefore, can be used as an predictor for clinical efficacy of troglitazone in patients with type 2 diabetes.
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PMID:Serum leptin level as an indicator to predict the clinical efficacy of troglitazone in patients with type 2 diabetes mellitus. 1148 31

Acylation-stimulating protein is an adipocyte-derived protein that has recently been suggested to play an important role in the regulation of triglyceride storage. To date, little information has been reported with regard to fasting acylation-stimulating protein levels and its relation to metabolic control, leptin, and/or lipids in subjects with diabetes mellitus. We therefore evaluated fasting acylation-stimulating protein, leptin, and lipid levels before and 4 months after improving glycemic control with sulfonylurea treatment in a group of poorly controlled obese women with type 2 diabetes and in age- and body mass index-matched nondiabetic obese women. Fasting plasma acylation-stimulating protein (49.67 +/- 19.73 vs. 48.49 +/- 20.70 nmol/liter) and leptin concentrations (33.7 +/- 23.2 vs. 26.2 +/- 10.6 ng/ml) were not significantly different between the groups. Improvement of glycemic control produced parallel falls in fasting blood glucose and hemoglobin A1c. Plasma leptin concentrations were also significantly reduced (33.69 +/- 23.2 vs. 22.73 +/- 11.26 ng/ml; P = 0.036), whereas fasting acylation-stimulating protein concentrations were significantly increased after treatment (48.49 +/- 20.70 vs. 72,82 +/- 29,72 nmol/liter; P = 0.004). Nevertheless, lipids and apolipoprotein B did not significantly improve. We could not find any correlation between elevated acylation-stimulating protein levels and changes in body mass index, glucose, insulin, hemoglobin A1c, leptin, or lipid levels. Similarly, the decrement in circulating leptin levels observed after treatment did not correlate with changes in the levels of glucose, insulin, hemoglobin A1c, or any lipid parameters. We conclude that improved glycemic control increases fasting acylation-stimulating protein and decreases leptin concentrations, but not corrects critical lipid abnormalities in type 2 obese diabetic subjects. Moreover, altered plasma acylation-stimulating protein levels are not associated with changes in body mass index or lipid, leptin, insulin, or glucose levels. Thus, our findings suggest that improved glycemic control or insulin resistance is not responsible for abnormal fatty acid trapping, and failure of lipids to improve after treatment in our patients is consistent with the acylation-stimulating protein resistance concept.
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PMID:Improved glycemic control increases fasting plasma acylation-stimulating protein and decreases leptin concentrations in type II diabetic subjects. 1150 93


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