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Biomedical subjects

S Boyer

Publications and source records attributed to S Boyer.

At least 37 records · Page 2Linked to original sources
PubMed1991

Measurements of pertinent concentrations of oxygen in vivo.

A new method able to measure the concentration of oxygen in complex biological systems, including in vivo, has been developed using low-frequency EPR and newly characterized free radicals that are very sensitive to the concentration of oxygen. The free radicals (fusinite and lithium phthalocyanine) are very stable in tissues (for at least 150 days), apparently nontoxic, and can reflect oxygen concentrations that are less than the Km of cytochrome oxidase (0.1 microM or lower). Their biological stability is indicated by the fact that repeated measurements with fusinite of the concentration of oxygen in skeletal muscle have been made in the same animal for more than 150 days without any change in sensitivity or signs of toxicity.

Animals↗
PubMed1991

Recent evolutionary origin of the expression of the glial fibrillary acidic protein (GFAP) in lens epithelial cells. A molecular and genetic analysis of various mouse species.

We have investigated the phylogenetic distribution of the glial fibrillary acidic protein (GFAP) in lens epithelial cells (LEC) of various mouse species within the genus Mus. We have shown that lens GFAP is expressed in mice of the Mus musculus complex and in Mus spicilegus and Mus macedonicus species (L.GFAP(+) phenotype) while it is absent in Mus spretus, Mus caroli and Mus cooki species (L.GFAP(-) phenotype). Our results argue in favour of one of the phenograms illustrating the probable phylogenetic relationships between these species in the genus Mus. In animals where lens GFAP was immunodetected, Northern blots of lens RNA extracts hybridized with a mouse GFAP cDNA probe, revealed a single 2.7 kb band. Comparative Northern blot analysis of lens tissue from L.GFAP(+) mice or of brain tissue from L.GFAP(+) or L.GFAP(-) mice did not show any size heterogeneity of the GFAP mRNA. The pattern of the GFAP immunostaining of astroglial cells in brain was identical in both L.GFAP phenotypes. Analysis of interspecific crosses showed that the L.GFAP(+) character is transmitted in a dominant fashion and seems to be linked to the Mus musculus Gfap gene. In this study we have also confirmed the localization of the mouse Gfap gene on chromosome 11.

Animals↗
PubMed1990

Expression of glial fibrillary acidic protein and vimentin in mouse lens epithelial cells during development in vivo and during proliferation and differentiation in vitro: comparison with the developmental appearance of GFAP in the mouse central nervous system.

Analysis of glial fibrillary acidic protein (GFAP) and vimentin in mouse lens epithelial cells (MLEC) during ontogenesis revealed a two-step developmental expression similar to that observed in astrocytes. Vimentin was first immunostained at E11 corresponding with the closure of the lens vesicle, whereas GFAP was detected only after a further 7 days (E18); this protein appeared simultaneously in the mouse lens and CNS. In the latter case, it was present in the hypothalamic tanycytes and spinal cord. This similarity in the timing of appearance of GFAP in the non-neural MLEC and in fetal astrocytes suggests a common mechanism for its expression in tissues of different embryological origin. However, it has previously been observed that, in contrast to the situation in astrocytes, GFAP disappears from differentiating MLEC in vivo. We have shown that in vitro this protein also disappears rapidly from MLEC in the presence of fetal calf serum (FCS). However, the use of mouse serum instead of FCS inhibited the migration of MLEC out of the explant, and in these cells GFAP persisted.

Animals↗
PubMed1988

[The role of Chlamydia trachomatis in the infectious etiology of extra-uterine pregnancy].

The study was carried out in two different hospital centres on a series of 55 women who had ectopic pregnancies compared with 2 control groups. The study concerned taking samples from cells in the pelvis to culture for Chlamydia trachomatis and to estimate the levels of anti-Chlamydia antibodies. The cultures were positive in 30% of the cases and the serology was positive in 52% of the cases. This difference is significant when compared with the control groups (p less than 0.001). There was no significant statistical difference as far as positive cultures were concerned between the groups of women who had or had not had previous tubal infertility or a history of salpingitis. It seems that Chlamydia trachomatis can itself therefore be a direct cause for the development of an ectopic pregnancy.

Abortion, Spontaneous↗
PubMed1985

Pharmacologic manipulation of fetal hemoglobin synthesis.

The ease with which HbF production can be increased in subjects with SS disease was a totally unexpected phenomena on the basis of previous models of HbF synthesis. The fact that these drugs induce rapid increases in F cell production and increase HbF per F cell and HbS in non-F cells, may be important clues as to the mechanism of the action of these drugs. It is far from clear whether either one of these agents will be eventually used as therapy for subjects with SS disease. The more recent problems with cytotoxicity illustrated by HU, and the potential carcinogenic effect of 5-aza limit our ability to perform large controlled clinical trials at this time. The observation that HbF production is increased by two agents which perturb DNA replication may be important clues in understanding not only the origins of differential gamma versus beta globin gene expression but also the mechanism by which HbF is restricted to expression in only certain cells during normal erythroid maturation.

Anemia, Sickle Cell↗
PubMed1985

[Fetal ascites as a manifestation of infantile sialidosis. Significance of a study of oligosaccharides in amniotic fluid].

Non immune hydramnios and fetal ascite are demonstrated at 31 weeks gestation. There is no familial story. All etiologic investigations (repeated ultrasonographic examinations, amniocentesis) are negative. The delivered girl has a normal development. She presents a congenital ascite and edema. The diagnosis of sialidosis (mucolipidosis type I) is supported by the early finding of vacuolated lymphocytes, the excretion of oligosaccharides in the urine and, finally, the results of the study of alpha-D-neuraminidase fibroblasts and others lysosomal enzymes activities. Oligosaccharides and enzymic studies provide same results in amniotic fluid. Authors point the particular interest of amniotic fluid oligosaccharides study when the etiologic diagnosis of idiopathic fetal ascite or hydrops is to be done.

Adult↗
PubMed1983

Treatment of sickle cell anemia with 5-azacytidine results in increased fetal hemoglobin production and is associated with nonrandom hypomethylation of DNA around the gamma-delta-beta-globin gene complex.

Increased production of fetal hemoglobin (HbF) was observed in a patient with sickle cell anemia treated with 5-azacytidine. Each of four courses of therapy resulted in a rapid and prolonged increase in the percentage of HbF containing reticulocytes (F reticulocytes) and HbF containing erythrocytes (F cells). The percentage of HbF in peripheral blood rose from 1.8 to 8.9%. The rise in HbF production was accompanied by an increase in peripheral blood hemoglobin concentration from 8 to 12 g/dl and an increase in mean erythrocyte volume. Treatment with 5-azacytidine resulted in hypomethylation of total genomic and a Y-chromosome-specific DNA fragment isolated from both peripheral blood and bone marrow. Of 15 restriction enzyme sites around the gamma-delta-beta-globin gene complex, only 2 became hypomethylated: one 107 bases 5' to the gamma G and the other 107 bases 5' to the gamma A globin genes.

Adult↗
PubMed1981

[Mucopolysaccharidosis type VII. Clinical, radiological and biochemical studies in a neonatal case (author's transl)].

Clinical, radiological and biochemical findings are described in a male newborn with type VII mucopolysaccharidosis (betaglucuronidase deficiency). A metabolic storage disease was likely at birth, because of morphological and radiological features and granulated cells in blood and bone marrow. A study of glycosaminoglycans has been performed in urine and various organs post mortem. Enzymatic deficiency was found in serum, leucocytes, skin fibroblasts, liver, spleen and kidneys. Low activities were present in both parents.

Bone and Bones↗
PubMed1978

E. Cowles Andrus.

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Cardiology↗