Category Archives: Enzymes

Expression of the Erythropoietin Receptor: MATERIALS AND METHODS(3)

The procedure for trophoblast isolation was based on the method of Kliman et al. with modifications. Briefly, the basal plate was removed, and approximately 50 g of villous tissue was harvested and teased into small fragments. Villous trophoblast cells were released by four sequential trypsin digestions (trypsin grade III; Sigma Chemical Co., St. Louis, MO). DNase I (grade II; Boehringer Mannheim, Indianapolis, IN) was used to prevent cellular aggregation. The first digestion was routinely discarded, as it contained few trophoblast cells and mainly red blood cells and leukocytes. The digests were layered over FBS and centrifuged to remove cellular debris and inactivate trypsin. antibiotic levaquin

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: DISCUSSION(6)

The results clearly indicate that TGFp modulates both glycolysis and Krebs cycle activities during human preantral follicle development. TGFp has been shown to stimulate glycolytic activity in rat kidney cells and glucose uptake by cell monolayers. The induction of key glycolytic enzymes in human preantral follicles by TGFp1 may reflect an additional level of regulation by this growth modulator to promote follicular differentiation. TGFp1 potentiates FSH action on hamster follicular cells and estrogen-induced DNA synthesis in rat granulosa cells. FSH induces TGFp receptor type II in human preantral follicles in classes 1 and 2 and in hamster preantral follicles, and TGFp2 in hamster preantral follicles. Granulosa cells of human preovulatory follicles exposed in vivo to exogenously administered gonadotropins express TGFp receptor types I and II protein, and TGFp1 ligand has been detected in human follicular fluid. Development of class 1 follicles to class 2 requires cell division as well as the onset of functionality, such as steroidogenesis. The unique regulation of some of the key enzymes of glucose metabolism by TGFp in class 1 and class 2 follicles indicates that this growth factor differentially influences preantral follicles at different stages of development. buy yasmin online

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: DISCUSSION(5)

DISCUSSION(5)

Although no report is available on the role of intraovar-ian growth factors on follicular glucose metabolism for any species, EGF has been studied for its role in glucose metabolism in the liver and renal tubular cells. EGF stimulation of MDH activity for class 1 follicles may indicate a transient rise in mitochondrial glucose oxidation as observed in perfused rat liver preparation. EGF stimulates mitochondrial gluconeogenetic enzymes in rat hepatocytes and PFK mRNA expression in cultured rat fibroblasts via mitogen-activated protein kinase. IGF-I induction of PK and MDH activities in class 1 follicles, as well as PFK and PK activities in class 2 follicles, suggests that intraovarian growth modulators involving the tyrosine kinase signal transduction system may affect follicular glucose metabolism in a similar fashion. buy ventolin inhalers

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: DISCUSSION(4)

A mathematical model also indicates that energy production in more centrally located cells of large preantral follicles may depend on anaerobic glycolysis because of the existence of a rarefied oxygen gradient from the peripheral to central layers of granulosa cells; however, it is important to consider that the availability of oxygen to the central core of preantral follicles with 3-4 layers of granulosa cells, such as class 2 human preantral follicles, may be greater than that to preantral follicles with 6-8 layers of granulosa cells. buy cipro

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: DISCUSSION(3)

DISCUSSION(3)

The exact reason(s) for the differences in FSH and LH action on the activities of PFK and PK versus MDH is not known; however, the results strongly indicate that some of the major regulatory steps of glycolysis and the Krebs cycle may be influenced differently by FSH and LH, and that the influence varies with the maturational status of the follicle. Nilsson has demonstrated that LH significantly stimulates lactic acid production in eCG-treated rat preovulatory follicles in vitro, indicating an increase in glycolysis by gonadotropins; and this mode of energy production may be favored in vitro for preantral follicles as observed in the present studies. flovent inhaler

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: DISCUSSION(2)

We have previously demonstrated that FSH stimulates DNA synthesis and steroidogenesis and growth factor receptor induction in human preantral follicles. Boland et al. have documented that the degree of lactate production in vitro by preantral mouse follicles with surrounding theca/stromal tissue increases steadily as follicles develop into the antral stage, and that FSH either alone or in combination with LH stimulates the rate of lactate production. buy birth control online

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: DISCUSSION(1)

DISCUSSION(1)

The results of the present study provide strong evidence that preantral human follicles utilize both the glycolytic and the Krebs cycle for energy production when exposed to gonadotropins; the findings also show for the first time that intraovarian growth factors, apart from their well-known mitogenic and steroidogenic (see for references) effect, differentially influence glucose metabolic capacity of preantral follicles by modulating the activities of essential regulatory enzymes of the glycolytic and Krebs cycle. ventolin 100 mcg

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: RESULTS(2)

The basal PK activity was almost undetectable in follicles cultured for 24 h without any hormonal stimulus; however, significant (p < 0.05) stimulation was noted in response to FSH and LH (Fig. 2). As with the PFK activity, FSH stimulation of PK activity for class 2 follicles was more pronounced (55-fold) than for class 1 follicles (6fold). Similarly, LH was more effective than FSH for class 1 in comparison to class 2 follicles (Fig. 2, A and B); however, the degree of LH stimulation for class 2 follicles was significantly (p < 0.5) greater than for class 1. Both EGF and IGF-I stimulated Pk activity almost similarly for class 1 and class 2 follicles (Fig. 2, A and B). proventil inhaler

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: RESULTS(1)

RESULTS(1)

The activities of glycolytic and Krebs cycle enzymes were evaluated to provide an understanding of the extent of glucose metabolic capacity of human preantral follicles and their regulation by gonadotropins and intraovarian growth factors. Under the basal condition, follicular PFK activity was low for both class 1 and class 2 follicles. However, the enzyme activity increased significantly in response to both FSH and LH compared to control (Fig. 1). Cheap Diskus Advair

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Activities of Glucose Metabolic Enzymes in Human Preantral Follicles: MATERIALS AND METHODS(6)

Enzyme activity was determined as described by Par-ia et al. in the mitochondrial fraction from the rate of NADH oxidation at 340 nm. The reaction mixture consisted of 1 ml of 100 mM potassium phosphate buffer, pH 7.5, containing 50 mM oxaloacetate and 20 mM NADH. The rate of NADH oxidation following the addition of 10 ^l of follicular pellet fraction was recorded as described in the previous section. MDH activity was expressed as millimoles NADH oxidized per minute per milligrams protein. Buy Advair Diskus Online

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