Pituitary luteinizing hormone microheterogeneity in the afternoon of proestrus in rats: some new insights

OBJECTIVE : The aim of the present report was to determine the possible modifications in rat pituitary LH isoforms induced by the spontaneous increase in GnRH at the time of the preovulatory gonadotropin surge. DESIGN: The changes in the quantitative pattern and relative proportions of pituitary LH isoforms in rats on the afternoon of proestrus [INT-P(PM)] were evaluated by comparison with other stages of the estrous cycle (diestrus-1, diestrus-2 and estrus) and ovariectomized (7 and 30 days earlier) animals killed in the morning and in the afternoon of the corresponding day. METHODS: The chromatofocusing technique (pH gradient 11.00-7.00) was used to analyze the different molecular species of intrapituitary LH. RESULTS: Pituitary LH from diestrus-1 animals, considered as a baseline pattern in the cycling rat, eluted as 11 isoforms distributed in pH 9.62-8.82, with greater percentages in pH 9.50-9.01. Except for INT-P(PM) pituitaries, there were no major differences in the pattern of LH heterogeneity in the pituitaries of rats from various stages of the cycle. In contrast, significant changes in the charge distribution and relative abundance of LH isoforms were found in the pituitaries from INT-P(PM) rats. INT-P(PM) pituitaries resolved in 16 LH isoforms with a significant shift to less alkaline pIs (pH 9.62-8.11), the more abundant being focused within pH 9.00-8.51. Conversely, a shift to more basic isoforms resulted after ovariectomy, leading to the accumulation of less mature isoforms in the gonadotrope. CONCLUSIONS: Presumably, the use of animals on INT-P(PM), at the time of the preovulatory LH surge, made it possible to discriminate such changes in LH isoform distribution. That GnRH, released in association with the rising phase of the LH surge, induces these changes in pituitary LH polymorphism appears to be the most likely possibility. In a previous study we demonstrated that GnRH stimulated galactose incorporation into LH in vitro. In the case of pituitaries from INT-P(PM) rats, the shift toward less alkaline isoforms could potentially result from sialylation of increased terminal galactose.     

Hemophilia A and B are associated with abnormal spatial dynamics of clot growth

To gain greater insight into the nature of the bleeding tendency in hemophilia, we compared the spatial dynamics of clotting in platelet-free plasma from healthy donors and from patients with severe hemophilia A or B (factor VIII:C or IX:C<1%). Clotting was initiated via the intrinsic or extrinsic pathway in a thin layer of nonstirred plasma by bringing it in contact with the glass or fibroblast monolayer surface. The results suggest that clot growth is a process consisting of two distinct phases, initiation and elongation. The clotting events on the activator surface and the preceding period free of visible signs of clotting are the initiation phase. In experiments with and without stirring alike, this phase is prolonged in hemophilic plasma activated by the intrinsic, but not the extrinsic pathway. Strikingly, both hemophilia A and B are associated with a significant deterioration in the elongation phase (clot thickening), irrespective of the activation pathway. The rate of clot growth in hemophilic plasma is significantly lower than normal and declines quickly. The resulting clots are thin, which may account for the bleeding disorder.     

Degradation of African locust bean oil by Bacillus subtilis and Bacillus pumilus isolated from soumbala,a fermented African locust bean condiment

AIMS: To investigate predominant isolates of Bacillus subtilis and B. pumilus in soumbala, a fermented African locust bean condiment, for their ability to degrade African locust bean oil (ALBO). METHODS AND RESULTS: Agar diffusion test in tributyrin and ALBO agar was used for screening of the isolates for esterase and lipase activity, respectively. The quantity and the profile of free fatty acids (FFA) during 72 h of degradation of ALBO by the Bacillus isolates were studied by titration and gas chromatography. The degradation of tributyrin and ALBO was variable among the isolates. Two strains of B. subtilis and two strains of B. pumilus showed significantly higher esterase and lipolytic activities than the others. The degradation ALBO was most pronounced in enriched nutrient agar except for one isolate of B. pumilus degrading ALBO to the same extent regardless of the enrichment. The quantity of FFA released from ALBO by the most lipolytic strains of Bacillus increased mainly between 0 and 24 h and differed among the isolates. The profile of FFA was similar for the Bacillus isolates with oleic acid (C18:2) occurring as the major FFA in all the samples except in samples incubated with B. subtilis B9 where stearic acid (C18) was dominant. CONCLUSION: Bacillus isolates from soumbala showed high strain dependent lipolytic activity against ALBO. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to the selection of Bacillus strains to be used as starter cultures for controlled production of soumbala.     

Polymeric systems with antithrombin activity for thermally activated targeting

Copolymers of N,N-diethylacrylamide and N-acryloylphthalimide with lower critical solution temperature (LCST) were synthesized by radical copolymerization. Polymeric systems with antithrombin activity and LCST were prepared via a reaction of amino groups of hirudin with phthalimide groups of the copolymers. On increasing hirudin content, LCST of the polymeric systems increased. The antithrombin activity of polymeric systems obtained by hirudin immobilization on copolymer carriers was inversely related to the content of the copolymer, amounting to 6% of the activity of native hirudin.     

Transplantation of stem/progenitor cells of human brain into the brain of adult rats

We studied the development of stem/progenitor cells of the human brain transplanted in the adult rat brain after reproduction in an in vitro tissue culture. It was preliminarily shown by the immunological methods that the stem cells grown in a medium with growth factors formed neurospheres, which were heterogenous and contained both stem and progenitor cells of the human brain. The cells were implanted in the hippocampus, striatum, or lateral ventricle of the rat brain as a suspension or aggregates (neurospheres) and their behavior and differentiation were studies within 10, 20, and 30 days using the morphological and immunochemical methods. The cultured cells of the human brain continued their development in the rat brain, migrated, and formed neurons and astrocytes. The white mater fibers, lateral ventricle wall, and perivascular spaces served as the main pathways of migration. The neuronal differentiation was shown by staining with antibodies to beta-tubulin III, neurofilaments-70, and calbindin. Some growing nerve cells had long processes with growth cones. At the same time, some transplanted cells retained the undifferentiated state within one month after the implantation, as shown by the vimentin expression.     

Methionine sulfoximine and phosphinothricin--glutamine synthetase inhibitors and activators and their herbicidal activity (A review)

Derivatives of methionine sulfoximine (MSO) and phosphinothrycin (PPT), which are analogues of glutamate, exhibit selective herbicidal activity. This effect is accounted for by impairments of nitrogen metabolism, resulting from inhibition of its key enzyme in plants, glutamine synthetase (EC 6.3.1.2). Inhibition of the enzyme causes ammoniac nitrogen to accumulate and terminates the synthesis of glutamine. Changes in the content of these two metabolites (excess ammonium and glutamine deficiency) act in a concert to cause plant death. However, low concentrations of MSO, PPT, and their metabolites produce an opposite effect: glutamine synthetase is activated, with concomitant stimulation of plant growth and productivity. The mechanisms whereby MSO and PPT affect glutamine synthetase activity are discussed in the context of nitrogen metabolism in plants.