Variation in the ovarian reserve Is linked to alterations in intrafollicular estradiol production and ovarian biomarkers of follicular differentiation and oocyte quality in cattle

The mechanisms whereby the high variation in numbers of morphologically healthy oocytes and follicles in ovaries (ovarian reserve) may have an impact onovarian function, oocyte quality, and fertility are poorly understood. The objective was to determine whether previously validated biomarkers for follicular differentiation and function, as well as oocyte quality differed between cattle with low versus a high antral follicle count (AFC). Ovaries were removed (n = 5 per group) near the beginning of the nonovulatory follicular wave, before follicles could be identified via ultrasonography as being dominant, from heifers with high versus a low AFC. The F1, F2, and F3 follicles were dissected and diameters determined. Follicular fluid and thecal, granulosal, and cumulus cells and the oocyte were isolated and subjected to biomarker analyses. Although the size and numerous biomarkers of differentiation, such as mRNAs for the gonadotropin receptors, were similar, intrafollicular concentrations of estradiol and the abundance of mRNAs for CYP19A1 in granulosal cells and ESR1, ESR2, and CTSB in cumulus cells were greater, whereas mRNAs for AMH in granulosal cells and TBC1D1 in thecal cells were lower for animals with low versus a high AFC during follicle waves. Hence, variation in the ovarian reserve may have an impact on follicular function and oocyte quality via alterations in intrafollicular estradiol production and expression of key genes involved in follicle-stimulating hormone action (AMH) and estradiol (CYP19A1) production by granulosal cells, function and survival of thecal cells (TBC1D1), responsiveness of cumulus cells to estradiol (ESR1, ESR2), and cumulus cell determinants of oocyte quality (CTSB).

Follicle-stimulating hormone isoforms and plasma concentrations of estradiol and inhibin A in dairy cows with ovulatory and non-ovulatory follicles during the first postpartum follicle wave

Following parturition, all cows display a wave of ovarian follicular growth, but a large proportion fail to generate a preovulatory rise in estradiol, and hence fail to ovulate. Follicle-stimulating hormone (FSH) exists as multiple isoforms in the circulation depending on the type and extent of glycosylation, and this has pronounced effects on its biological properties. This study examined differences in plasma FSH, estradiol, and inhibin A concentrations, and the distribution of FSH isoforms in cows with ovulatory or atretic dominant follicles during the first postpartum follicle wave. Plasma FSH isoform distribution was examined in both groups during the period of final development of the dominant follicle by liquid phase isoelectric focusing. Cows with an ovulatory follicle had higher circulating estradiol and inhibin A concentrations, and lower plasma FSH concentrations. The distribution of FSH isoforms displayed a marked shift toward the less acidic isoforms in cows with ovulatory follicles. A higher proportion of the FSH isoforms had a pl>5.0 in cows with ovulatory follicles compared to those with atretic follicles. In addition, cows with ovulatory follicles had greater dry matter intake, superior energy balance, elevated circulating concentrations of insulin and insulin-like growth factor-I, and lower plasma nonesterified fatty acids. The shift in FSH isoforms toward a greater abundance of the less acidic isoforms appears to be a key component in determining the capability for producing a preovulatory rise in estradiol, and this shift in FSH isoforms was associated with more favorable bioenergetic and metabolic status. (C) 2008 Elsevier Inc. All rights reserved.

Mapping antimalarial pharmacophores as a useful tool for the rapid discovery of drugs effective in vivo: design, construction, characterization, and pharmacology of metaquine

Resistant strains of Plasmodium falciparum and the unavailability of useful antimalarial vaccines reinforce the need to develop new efficacious antimalarials. This study details a pharmacophore model that has been used to identify a potent, soluble, orally bioavailable antimalarial bisquinoline, metaquine (N,N'-bis(7-chloroquinolin-4-yl)benzene-1,3-diamine) (dihydrochloride), which is active against Plasmodium berghei in vivo (oral ID50 of 25 mu mol/kg) and multidrug-resistant Plasmodium falciparum K1 in vitro (0.17 mu M). Metaquine shows strong affinity for the putative antimalarial receptor, heme at pH 7.4 in aqueous DMSO. Both crystallographic analyses and quantum mechanical calculations (HF/6-31+G*) reveal important regions of protonation and bonding thought to persist at parasitic vacuolar pH concordant with our receptor model. Formation of drug-heme adduct in solution was confirmed using high-resolution positive ion electrospray mass spectrometry. Metaquine showed strong binding with the receptor in a 1: 1 ratio (log K = 5.7 +/- 0.1) that was predicted by molecular mechanics calculations. This study illustrates a rational multidisciplinary approach for the development of new 4-aminoquinoline antimalarials, with efficacy superior to chloroquine, based on the use of a pharmacophore model.