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Biomedical subjects

H Boulekbache

Publications and source records attributed to H Boulekbache.

32 records · Page 2Linked to original sources
PubMed1986

Perinatal changes in adenine nucleotide content of developing rat kidney.

Adenine nucleotides have been measured in fetal and newborn kidneys of rat using the luciferine-luciferase method. In fetuses, between days 18 and 21 of gestation there is a drop of the relative amount of ATP in the renal nucleotide pool. Consequently, the kidneys of 21 days-old fetuses have lowered ATP/ADP ratio (3.6) and energy charge (0.80) compared with values found on day 18 (6.9 and 0.91, respectively); this relative energy deficit is heightened in progesterone induced postmaturity. One hour after delivery whether the gestational stage is 21, 22 or 23 days, there is a rise in ATP and a decrease in AMP content which restore a high energy level in kidney of the newborn and a 30% increase in the total adenine nucleotide pool.

Adenine Nucleotides↗
PubMed1985

Mineralization in vitro of matrix formed by osteoblasts isolated by collagenase digestion.

Osteoblasts from calvaria of 18-day-old fetal Sprague-Dawley rats were isolated using a dissecting procedure followed by collagenase digestion. Freshly isolated or previously frozen cells were cultured for up to 4 weeks in a Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum and 50 micrograms/ml ascorbic acid, with or without 10 mM beta-glycerophosphate. Most of the cells were alkaline phosphatase positive throughout the culture period and expressed a type-I collagen as assessed by immunofluorescence. Cells cultured in the presence of beta-glycerophosphate formed a matrix with type-I collagen in 7 days. The matrix underwent mineralization in less than 2 weeks. In the absence of beta-glycerophosphate, only the formation of a nonmineralized matrix was observed. Electron-microscopic examination revealed osteoblasts embedded in a dense network of collagen fibers, with a well-defined mineralization process in association with matrix vesicles. Scanning electron-microscopy showed that the matrix composed of layers of irregularly shaped spread cells with smooth surfaces trapped in a fiber matrix. No mineralization process was observed when rat skin fibroblasts were cultured under similar conditions. These data demonstrate the ability of enzymatically isolated osteoblasts cultured in the presence of beta-glycerophosphate to form bone in vitro, and that this process is similar to bone formation in vivo.

Alkaline Phosphatase↗
PubMed1985

Evidence for the role of fibronectin in amphibian gastrulation.

In amphibian embryos, fibronectin (FN) assembles as a fibrillar network on the roof of the blastocoel cavity, preceding mesodermal cell migration. Local inversion of the ectoderm to produce a site where no FN is available prevents mesodermal cell migration. Microinjection of monovalent antibodies to FN arrests gastrulation. A complete inhibition of mesodermal cell migration is obtained after microinjection of a synthetic peptide containing the cell binding site sequence of FN. Prevention of interactions between receptors and FN appears to be the primary cause for blockage of gastrulation.

Ambystoma mexicanum↗
PubMed1979

[Histochemical localization of lactate dehydrogenase (LDH) during cartilaginous cell differentiation in pleurodeles (Pleurodeles waltlii Michah].

As revealed in chondrogenetic cells the LDH activity that is very low during cellular migration, suddenly increases at the time of cytodifferentiation and reaches a peak at the onset of the first chondrocyte differentiation. A relationship is likely to exist between this increase in LDH-activity, chondroitin-sulfate synthesis and NAD metabolism.

Animals↗
PubMed1977

[Scanning electron microscopy study of membrane modification of blastomeres in the first stages of ovum development in trout (Salmo irideus Gibb.)].

Our study relates to the development of the membrane relief of the blastomeres of the trout egg from the stage before their division up to gastrulation. The surface of the blastoderm shows first a more or less dense system of crests which by the time of gastrulation are replaced by microvilli distributed over the whole surface of the enveloping layer. The deep blastomeres, loosely connected to each other by lamellipodes and filopodes produce only a few projections of their membranes and these are only semispherical bodies. Possible roles of the microvillosities in the respiratory exchange of the egg and in the motility of the enveloping layer, are considered.

Animals↗
PubMed1977

[Histochemical localization of lactate dehydrogenase in the trout embryo (Salmo irideus, Gibb) during early organogenesis of the cord and the neural tube].

The histochemical study of the LDH in the Trout embryo during the early organogenesis shows a specific localization in notochord cells, in mesodermic cells of the terminal knob and in some prosencephalic neuroblasts. The role of the LDH in the metabolism of NAD as well as in the energetic metabolism of embryonic cells is discussed.

Animals↗
PubMed1976

[Histochemical localization of lactate dehydrogenase in blastomeres during early development of the rainbow trout embryo (Salmo irideus Gibb)].

During the early development of the trout egg, some blastomers display a certain activity of the L.D.H., variable according to their position in the embryo. At the morula stage, the histochemical ltion of those blastomeres. On the contrary, during the gastrula stage, the blastomeres which have a high L.D.H. activity concentrate in the deep layer of the germ, in the "embryonic button", and in the germinal ring.

Age Factors↗
PubMedDate not supplied

Prevention of gastrulation but not neurulation by antibodies to fibronectin in amphibian embryos.

Gastrulation and formation of the neural plate are major steps in early vertebrate embryogenesis. Although morphogenetic movements leading to the formation of the primary germ layers have been extensively described, the mechanisms governing migration of mesodermal cells and their interactions with ectoderm remain ill-defined. A large body of evidence indicates that fibronectin (FN), a high molecular weight cell-surface-associated glycoprotein, promotes cell adhesion and cell migration throughout embryogenesis. FN has been detected at an early blastula stage in Pleurodeles waltlii. We now show that FN is a component of a dense fibrillar matrix underlying the blastocoel roof; in contrast, the exterior surface of the embryo is devoid of FN. Microsurgical inversion of part of the blastocoel roof does not prevent mesodermal cell migration except at the site of inversion where no FN matrix is available. Perturbation experiments using antibodies to FN demonstrate that the invagination of presumptive mesodermal cells does not occur when the monovalent antibodies are injected before or at the onset of gastrulation; on the other hand, the formation of a neural plate is not prevented when late gastrula stage embryos are treated with antibodies to FN. We conclude that the presence of FN is required for cell migration during gastrulation.

Animals↗