Search PubMed⌕ Search

Biomedical subjects

B Rolland

Publications and source records attributed to B Rolland.

33 records · Page 2Linked to original sources
PubMed1984

Astroglial cells: glucocorticoid target cells in the brain.

Glutamine synthetase (GS), an enzyme localized in astroglial cells in the brain, is directly implicated in brain detoxification. An ontogenic study of GS activity was performed in homogenates from four distinct brain areas in comparison with the respective astrocytes obtained in primary cultures. GS was induced by hydrocortisone in the astrocytes of all brain areas studied; only cerebellum and cerebral hemisphere astroglial cells had a higher specific activity when compared with the corresponding homogenates. N6O2-Dibutyryl adenosine 3',5'-cyclic monophosphate (dBc AMP), insulin, soluble brain factors, and noradrenaline (NA) were also able to modulate GS activity. Brain factors as well as dBc AMP interfered with hydrocortisone induction of GS. Regulation by hydrocortisone paralleled the variation in its concentration in brain during development. We conclude that astroglial cells are target cells for glucocorticoids, which may modulate ammonia detoxification in these cells.

Animals↗
PubMed1982

Glutamine synthetase activity during mouse brain development.

The specific activity of glutamine synthetase (GS) in mouse brain was 2-fold higher in the olfactory bulbs than in other regions. After birth, the specific activity of GS increased more rapidly in medulla oblongata and in olfactory bulbs, than in cerebral and cerebellar cortex. The activity of GS in primary cultures of brain hemispheres increased more slowly than in homogenates of whole brains. However, when astroblasts were treated in vitro with glucocorticoids or mouse brain extracts, GS activity reached 4 times the level measured in the homogenate of an adult mouse brain. We conclude that levels of GS activity may relate to the maturation of astrocytes, and propose that GS may be used as a marker of astrocytic maturation.

Animals↗
PubMed1981

Effect of prostaglandins and dibutyryl cyclic AMP on the morphology of cells in primary astroglial cultures and on metabolic enzymes of GABA and glutamate metabolism.

Prostaglandins (PGE1) and dibutyryl cyclic AMP (dBc AMP) induce similar morphological changes in astrocytes obtained in primary cultures. PGE1 and dBc AMP increased 2 enzymes of GABA and glutamate metabolism, GABA-T and AAT, but did not modify GDH and GLN-S. Prostaglandins probably affect the cAMP content of glial cells and act in the same way as dBc AMP on glial cell differentiation.

4-Aminobutyrate Transaminase↗
PubMed1981

Benzodiazepine receptors on primary cultures of mouse astrocytes.

Benzodiazepines bind to glial membranes on a single type of site, with a high affinity (KD = 5 x 10(-9) M) on about 100 fmol of sites per mg protein. The number of binding sites is increased when the membranes are treated with Triton X-100. Antiepileptic drugs such as clonazepam and phenobarbital and hypnotic drugs such as Ro-11-3128 and Ro-11-6896 are able in pharmacological concentrations to displace [3H]flunitrazepam from its glial binding sites.

Animals↗
PubMed1980

Two forms of GABA transaminase in pig brain: purification and properties.

Two forms of GABA transaminase which could be distinguished by ion-exchange chromatography have been separated and purified in pig brain. The two forms have different Km values for alpha-ketoglutarate and show different degrees of inhibition by various salts. Although the two forms are separable, they have identical antigenic properties, pH optima, and NH2 terminal amino acid composition, and they appear to be of the same molecular size. The biological significance or the relationship between multiple forms of GABA transaminase is not yet understood.

4-Aminobutyrate Transaminase↗
PubMedDate not supplied

In vivo evaluation of a trileaflet mechanical heart valve.

Design goals for a mechanical heart valve include duplicating the hemodynamic performance of the natural valve, eliminating the need for anticoagulants, and maintaining safety. The Lapeyre-Dassault (Dassault-Aviation, Paris, France) prosthetic valve, undergoing development, addresses these goals. The unique trileaflet design consists of a solid titanium ring and three leaflets. Prototypes of the valve fabricated with Delrin leaflets were implanted in the mitral position in six calves (70-90 kg). Four calves (Studies 1, 2, 3, 5) had long-term survival of 165, 158, 219, and 281 days, respectively. Two calves were killed, one on Day 37 and one on Day 39, after complications unrelated to the valve developed. In all calves heparin was given intravenously to maintain partial thromboplastin time at 1.5 to 2.0 x baseline for approximately 1 week. In Studies 1 and 2 full anticoagulation and antiplatelet therapy was given (orally administered sodium warfarin to maintain prothrombin time at 1.5 to 2.0 x baseline, along with aspirin (1 g/day) and dipyridamole 400 mg/day). In Study 3, all anticoagulation and antiplatelet therapy was discontinued at 1 month after implant. In Study 5, no anticoagulation therapy was given after the initial week of intravenous heparin; however, antiplatelet therapy was started on the fifth postoperative month and maintained until the study's end at 9 months. At 1, 2, 3, and 5 months, the mean plasma free hemoglobin level in the four long-term animals was 5.0 +/- 2.16, 6.0 +/- 3.83, 8.5 +/- 4.93, and 11.3 +/- 6.74 mg/dl, respectively. Hemolysis was not a problem. Valve performance during normal activity was excellent in all the calves, as evidenced by echocardiography and the overall appearance of good health. In the four completed long-term studies, left heart catheterization showed a mean valve pressure gradient of 11.57 +/- 1.26 mmHg and no apparent valvular regurgitation. Histopathologic examination of major organs showed no evidence of thromboembolic events. This study shows that the innovative design of this trileaflet valve performed well in initial in vivo testing, justifying further development.

Animals↗
PubMedDate not supplied

Lipopolysaccharides (LPS), up-regulate the IL-1-mRNA and down-regulate the glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS)-mRNAs in astroglial primary cultures.

The effect of lipopolysaccharides (LPS), a component of gram-negative bacteria, has been studied in both exponentially growing and confluent morphologically differentiated astroglial cells in primary cultures. The expression of glial fibrillary acidic protein (GFAP) and Glutamine Synthetase (GS) were investigated in parallel with proliferation and expression of IL-1 beta-mRNA. During the exponential growth, proliferation was severely inhibited by LPS. The effect was time- and dose-dependent. On confluent differentiated cells LPS induced an inhibition of cell proliferation which was associated with a down-regulation of GFAP-mRNA, GS-mRNA and GS expressions and with a transitory increase in IL-1 beta mRNA expression. The observed effects might interact with the astroglial developmental program and with the astroglial function.

Animals↗