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Leptin, the product of the ob gene, is a hormone secreted by fat cells which is primarily involved in the regulation of body weight. We have generated a leptin immunoadhesin (leptin-IgG) which was more potent than leptin alone at reducing body weight and food intake when injected into ob/ob mice. This molecule was used to identify high affinity binding sites on human embryonic 293 kidney cells and subsequently to isolate a cDNA encoding the leptin receptor from this cell line by expression cloning. This receptor corresponds to the short form of the recently isolated leptin receptor. Analysis of the expression pattern of the two forms of receptor by Northern blot, in situ hybridization and quantitative PCR showed that the receptor is expressed in most tissues but that the long form is prevalent in the hypothalamus.

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Muscle exercise induces intramuscular triglyceride (TG) accumulation and promotes mitochondrial maintenance in myotubes. However, the mechanism underlying exercise effects remains unknown. In this study, lactic acid was tested as a signaling molecule in C2C12 myotubes to understand the mechanism. Intracellular TG storage was induced in the cells by sodium lactate. The lactate activity was observed with an inhibition of the cAMP-PKA pathway as indicated by a reduction in the phosphorylation status of CREB (pCREB). Induction of pCREB signal by forskolin was blocked by pretreatment of cells with lactate. The impact of lactate on mitochondrial function was examined with a focus on the activities of two enzymes, MCAT (malonylCoA:ACP transferase) and PDH (pyruvate dehydrogenase). The enzyme activities were induced in the cells by lactate. Expression of the lactate receptor (GPR81) and lactate transporters (MCT1/4) were induced as well by lactate. The lactate activities were observed at concentrations between 4–64 mM, and were not dependent on the increase in intracellular pyruvate. Pyruvate treatment did not generate the same effects in the cells. Those results suggest that lactate may induce intramuscular TG storage and mitochondrial maintenance in myotubes through inhibition of the cAMP pathway by activation of GPR81 in a positive feedback manner.

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A general and reliable strategy for the detection of cocaine was proposed utilizing DNA-templated silver nanoclusters as signal indicators and the nicking endonuclease-assisted signal amplification method. This strategy can detect cocaine specifically with a detection limit as low as 2 nM by using a small volume of 5 μL.

In this in-vitro study, the effect of prohibitin (PHB) on glucose metabolism in eutopic endometrial stromal cells from women with endometriosis was investigated. Endometrial stromal cells were isolated from endometrium in women with endometriosis, in women without endometriosis, or from endometrioma tissues. Glucose metabolic phenotype of stromal cells were examined in vitro. Quantitative polymerase chain reaction was used to measure the mRNA expression of glycolysis-related genes. Glucose consumption and lactate production were examined after knockdown of PHB expression in women with endometriosis with siRNA. In endometrioma tissue, significantly increased glucose consumption, lactate production and aberrant expression of glycolysis-related enzymes were found in women with endometriosis compared with women who do not have endometriosis (P < 0.05 versus P < 0.001). In women with endometriosis, PHB mRNA and protein were under-expressed in endometrioma tissue; in women without endometriosis, PHB mRNA and protein were over-expressed. Knockdown of PHB expression in women with endometriosis increased glucose consumption, although it had no effect on lactate production. This study suggests that aberrant expression of glycolysis-related enzymes in endometrioma tissue is associated with enhanced glycolytic metabolism. The malignant-like feature may be partially caused by low-expression of PHB gene in endometriotic stromal cells.