Prenatal Hyperhomocysteinemia Impairs Hypothalamic Regulation of Reproductive Cycles in Rat Progeny.

Effects of prenatal hyperhomocysteinemia on hypothalamic regulation of estrous cycles were studied in female rats. In mature rats exposed to prenatal hyperhomocysteinemia, changes in the catecholamine content in hypothalamic areas responsible for the formation of the preovulatory surge of gonadotropin-releasing hormone were revealed: the level of norepinephrine in the medial preoptic area decreased and concentration of dopamine in the median eminence with arcuate nuclei increased. Administration of melatonin attenuated the observed changes, which can be related to neuroprotective effects of this hormone determined by its antioxidant properties.

The effects of thyroxine isomers on free-radical oxidation processes in subcellular fractions of rat cerebral cortex.

Measurements made by chemiluminescence (CL) were used to estimate effective D- and L-thyroxine concentrations and to study their effects on free-radical oxidation processes in the mitochondrial and synaptosomal fractions of rat cerebral cortex in vitro. These experiments showed that in a model system containing riboflavin, the antioxidant activity of D-T4 was 2.2 times greater than that of L-T4. The effective concentrations for the two forms of thyroxine were I50 = 74.3 +/- 7.1 microM for D-T4 and I50 = 154.7 +/- 12.3 microM for L-T4. Studies of the in vitro effects of thyroxine on the membrane fraction of the cerebral cortex were based on luminol-dependent peroxide CL. At physiological concentrations (10 nM), both isomers of the hormone had identical antioxidant activities, which were stronger in the mitochondrial traction, where the intensity of CL decreased by 69% and 66%, compared with 45% and 46% decreases in the synaptosomal fraction. Since the D-form has no hormonal activity, it is suggested that this effect is associated with the phenolic nature of thyroxine.

Fluorescent microscopic study of epithalon binding in maternal and fetal rabbit tissues in health and under conditions of placental insufficiency.

Epithalon (regulatory tetrapeptide) labeled with dansil (fluorescent stain) easily penetrates into all tissues and organs of pregnant rabbit females and through the placenta into fetal organs. Incorporation of labeled epithalon in placental tissues is more often observed in fetuses developing under conditions of placental insufficiency than in normal fetuses.

Study of DNA internal dynamics by quasi-elastic light scattering.

We have studied the large-scale internal fluctuations in DNA coils by using quasi-elastic light-scattering spectroscopy. We have measured the angular dependence of the first cumulant of the scattered-light autocorrelation function. Within the q (3) domain of this dependence, we observed the transition from the asymptotic behavior predicted for good solvents to the asymptotic behavior predicted for ? conditions. This allowed us to determine the screening length of volume interactions in DNA chains. Analysis of the autocorrelation functions by a regularization procedure allowed us to reconstruct the mode composition of the scattered light and to determine the relaxation time of the fluctuations in the coil size.

Effects of peptides on generation of reactive oxygen species in subcellular fractions of Drosophila melanogaster.

We studied the effects of Epithalon (Ala-Glu-Asp-Gly) and Vilon (Lys-Glu) on free radical processes in highly inbred HA(+)line of Drosophila melanogaster. Vilon inhibited generation of reactive oxygen species in mitochondria, but stimulated this process in the cytosol. We found sex- and age-related differences in the generation of reactive oxygen species and cytosol antioxidant activity.

Glutathione-dependent system of antioxidant defense in the placenta in preterm delivery.

Components of the antioxidant defense system in placental tissues were studied in women with normal pregnancy and full-term delivery and women with spontaneous abortions at 28-36 weeks. In women with spontaneous abortions glutathione peroxidase activity in placental tissues increased and the content of SH compounds decreased, which led to exhaustion of the antioxidant defense system. Glutathione-S-transferase activity also decreased, which attests to impaired detoxifying function of the placenta.

Effect of chronic inhalation of toluene and dioxane on activity of free radical processes in rat ovaries and brain.

The effects of toluene and dioxane inhalations on the intensity of free radical oxidation in rat ovaries and brain cortex were studied. Both toxins in a dose 10-fold surpassing the maximum permissible concentration increased activity of glutathione peroxidase in brain tissue; moreover, toluene increased chemiluminescence intensity, which attested to activation of free radical processes. In ovarian tissue toluene increased activities of glutathione peroxidase and catalase and the intensity of lipid peroxidation. These changes were associated with the appearance of normally absent circadian rhythm.

Three-dimensional (3-D) structures formed by immortalized human fibroblast cells in simulated microgravity.

3-D structures were obtained at rotatory cultivation of CH immortalyzed human fibroblasts attached to glass microcarrier beads. The morphology of cells from these cultures was studied by scanning electron microscopy. A number of structural alterations in fibrillar filopodia of CH cells were revealed as compared with cells grown in stationary monolayer cultures, namely, smaller length, uneven caliber, the presence of curvatures, and disturbed branching pattern. Filopodia displayed unusual formations: protuberance-like and "mammoth's tusk"-like off-shoots, foamy spreadings in distal segments, and spiral windings of filopodia. The susceptibility of CH cells morphology to mechanical environment makes them a promising model for gravitational biology studies.

An alpha-L-fucosidase from Thermus sp. with unusually broad specificity.

An alpha-L-fucosidase (E.C. 3.2.1.51) exhibiting a wide aglycon specificity expressed in ability of cleaving alpha1 --> 6-, alpha1 -->3-, alpha1 --> 4-, and alpha1 --> 2-O-fucosyl bonds in fucosylated oligosaccharides, has been isolated from culture filtrate of Thermus sp. strain Y5. The alpha-L-fucosidase hydrolyzes p-nitrophenyl alpha-L-fucopyranoside with V(max) of 12.0 +/- 0.1 microM/min/mg and K(m) = 0.20 +/- 0.05 mM and is able to cleave off about 90% of total L-fucose from pronase-treated fractions of fucosyl-containing glycoproteins and about 30% from the native glycoproteins. The purified enzyme is a tetramer with a molecular mass of 240 +/- 10 kDa consisting of four identical subunits with a molecular mass of 61.0 +/- 0.5 kDa. The N-terminal sequence showed homology to some alpha-L-fucosidases from microbial and plant sources. Hydrolysis of p-nitrophenyl alpha-L-fucopyranoside occurs with retention of the anomeric configuration. Transglycosylating activity of the alpha-L-fucosidase was demonstrated in reactions with such acceptors as alcohols, N-acetylglucosamine and N-acetylgalactosamine while no transglycosylation products were observed in the reaction with p-nitrophenyl alpha-L-fucopyranoside. The enzyme can be classified in glycosyl hydrolase family 29.