Publications by authors named "Valentina M Fokina"

Pravastatin is currently under evaluation for prevention of preeclampsia. Factors contributing to placental disposition of pravastatin are important in assessment of potential undesirable fetal effects. The purpose of this study was to identify the uptake transporters that contribute to the placental disposition of pravastatin.

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Background: Bupropion (BUP) has a potential to be an effective pharmacotherapy for smoking cessation during pregnancy. Smoking during pregnancy stimulates placental carbonyl reductases that catalyze the biotransformation of BUP. 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) is a potent carcinogen of cigarette smoke.

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Background: Bupropion is used to treat depression during pregnancy. However, its usefulness as a smoking cessation aid for pregnant women is not fully known.

Objective: The objective of the study was to evaluate the preliminary efficacy of bupropion sustained release for smoking cessation during pregnancy.

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Bupropion sustained release is used to promote smoking cessation in males and nonpregnant females. However, its efficacy as a smoking cessation aid during pregnancy is not reported. The pregnancy-associated changes in maternal physiology may alter the pharmacokinetics and pharmacodynamics of bupropion and consequently its efficacy in pregnant smokers.

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Background: Bupropion is used for treatment of depression during pregnancy. However, its use as a smoking cessation aid for pregnant women is currently under evaluation.

Objective: The aim of this opportunistic study was to investigate the transfer of bupropion and its major pharmacologically active metabolites, hydroxybupropion and threohydrobupropion, across the placenta in vivo.

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This report describes the development and validation of an LC-MS/MS method for the quantitative determination of glyburide (GLB), its five metabolites (M1, M2a, M2b, M3 and M4) and metformin (MET) in plasma and urine of pregnant patients under treatment with a combination of the two medications. The extraction recovery of the analytes from plasma samples was 87-99%, and that from urine samples was 85-95%. The differences in retention times among the analytes and the wide range of the concentrations of the medications and their metabolites in plasma and urine patient samples required the development of three LC methods.

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Perfusion of 17-alpha-hydroxyprogesterone caproate (17HPC) via the maternal circuit of a dually perfused human placental lobule resulted in the extensive formation of 2 metabolites. On the other hand, human placental microsomes biotransformed 17HPC into 5 monohydroxylated metabolites, which did not correspond to those formed during perfusion. The goal of this investigation was to determine the subcellular localization of the enzymes responsible for the biotransformation of 17HPC during its perfusion in human placenta.

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The aim of this investigation was to determine the biotransformation of bupropion by baboon hepatic and placental microsomes, identify the enzyme(s) catalyzing the reaction(s) and determine its kinetics. Bupropion was metabolized by baboon hepatic and placental microsomes to hydroxybupropion (OH-BUP), threo- (TB) and erythrohydrobupropion (EB). OH-bupropion was the major metabolite formed by hepatic microsomes (Km 36±6 μM, Vmax 258±32 pmol mg protein(-1) min(-1)), however the formation of OH-BUP by placental microsomes was below the limit of quantification.

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We sought to determine whether gestational age affects the transplacental transfer and metabolism of buprenorphine (BUP). Transfer of BUP (10 ng/mL) and its [ (3)H]-isotope was determined across placentas of 30 to 34 weeks of gestation utilizing the technique of dual perfusion of placental lobule. Concentration of the drug in trophoblast tissue and in maternal and fetal circuits was determined by liquid scintillation spectrometry.

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One of the factors affecting the pharmacokinetics (PK) of a drug during pregnancy is the activity of hepatic and placental metabolizing enzymes. Recently, we reported on the biotransformation of glyburide by human hepatic and placental microsomes to six metabolites that are structurally identical between the two tissues. Two of the metabolites, 4-trans-(M1) and 3-cis-hydroxycyclohexyl glyburide (M2b), were previously identified in plasma and urine of patients treated with glyburide and are pharmacologically active.

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To address the roles of Wnts in the development of the anterior eye, we used a chicken model to perform comprehensive expression analysis of all Wnt genes during anterior eye development. In analyzing the available genomic sequences, we found that the chicken genome encodes 18 Wnt proteins that are homologous to corresponding human and mouse proteins. The mRNA sequences for 12 chicken Wnt genes are available in GenBank, and mRNAs for six other Wnt genes (Wnt2, Wnt5b, Wnt7b, Wnt8b, Wnt9b, and Wnt16) were identified and cloned based on the homology to the genes from other species.

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We isolated the chicken homologue of opticin (cOptc), a member of the small leucine-rich repeat protein (SLRP) family. cOptc is expressed in the brain and the neural tube from stage 9 onward. At later stages, cOptc is expressed in the ciliary epithelium of the eye, optic stalk, Rathke's pouch, pharyngeal pouches, nasal pit and otic vesicle.

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