Thyroid hormone and development of the rat hippocampus: cell acquisition in the dentate gyrus

A quantitative autoradiographic histological study was carried out to examine mechanisms underlying the reduction in the rates of growth and of cell acquisition, including that of granule cells, in the dentate gyrus of hypothyroid rats. Thyroid deficiency in early life had no effect on the replication of intrinsic cells present in the polymorph and granular layers. The pyknotic index was also normal in the "proliferative zone", polymorph layer and granule cell layer, indicating that thyroid hormone had no effect on the survival of replicating, migrating or maturing granule cells. By contrast, the arrival of migrating cells from the "proliferative zone" to the granular layer was severely retarded in thyroid deficiency. This deficit was rapidly restored after a physiological dose of thyroxine given to hypothyroid rats. The present findings are consistent with our previous proposal that the role of thyroid hormone in the formation and/or the maintenance of nerve cells is related to changes in either cell migration or maturation, rather than to alterations in the replication of germinal cells.     

Principle and practice of in vitro fertilization. Role in the treatment of female sterility

In vitro fertilization (IVF) and embryo transfer (ET) appear to constitute a revolution in the reproductive sciences rather than merely a new technique in the treatment of sterility. Principle of IVF: IVF accomplishes in vitro the process than normally occurs in the oviduct between the ovulation of oocyte II and embryo implantation in the endometrium. This 4 day period (under normal conditions in the woman) involves 4 steps: recovery, fertilization, segmentation and transport. Performance of IVF: Recovery of the oocytes: The oocytes are recovered under celioscopic or echographic observation when they have completed cytoplasmic maturation and their first meiosis. A precise monitoring of ovulation (spontaneous or induced) should be performed using estrogen and LH assays. IVF provides an opportunity for evaluating the methods of ovulation induction and monitoring, as a function of the maturation of the oocytes recovered. Fertilization: When the oocyte has achieved maturing after several hours of incubation, fertilization is obtained 15 h contact with washed and capacitated spermatozoa (100 000/ml). This step is highly dependent on gametocyte quality: oocyte maturity and fecundity of spermatozoa, which can be estimated from the percentage of survival in the insemination medium. Segmentation occurs in culture at pH 7.28 in the presence of 5 per cent CO2 at 37 degrees C (pronucleus 15th, 2 blastomeres 26 h, 4-8 blastomeres 52 h). Embryo transfer is carried out when an embryo is present at 52 h. Only 1/10 of the embryo transfers result in successful implantation, which depends on the quality of the embryo; the quality can only be indirect criteria.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ultrastructural study of a muscle biopsy in a case of GM1 gangliosidosis type I.

The main ultrastructural findings in a muscle biopsy from a child aged 11 months with a GM1 gangliosidosis were cytoplasmic inclusions of two different types: (1) inclusions filled with a moderate electron dense and polymorphous material thought to correspond to ganglioside accumulation and lying only in the Schwann cells of intramuscular nerves. (2) Vacuolar inclusions regarded as containing polysaccharides and observed in perineurial cells, endothelium and pericytes of blood vessels, and also in muscle satellite cells. The muscle fibres only exhibited moderate and non-specific changes. The study shows that in a muscle biopsy of GM1 gangliosidosis the two characteristic types of storage deposits and their preferential localization in different cells may be demonstrated, providing that the intramuscular nerves and motor end plates are examined.     

The effect of education and self-monitoring of blood glucose on glycosylated hemoglobin in type I diabetes. A controlled 18-month trial in a representative population

The influence on glycosylated hemoglobin (HbA1) of formal education as compared with self-monitoring of blood glucose (SMBG) was studied in a randomized 18-month trial. All adult type I diabetics in a community were identified. Forty-one of these patients had had diabetes for 20 years or less. Thirty-seven patients were included in the study and finally randomized into four groups. Ten patients received individual formal education followed by SMBG, eight patients were instructed in SMBG without pre-education, nine patients were given only formal education and 10 patients made up a reference group. Education did not improve the mean HbA1 values. SMBG resulted in a decrease by 2% in HbA1, from 12 to 10% (p less than 0.05). The final HbA1 level, however, did not differ significantly between any of the groups. SMBG was accepted by 80% of the patients. The liability to hypoglycemia was about equal in the four groups. It was concluded that SMBG, but not education, improved metabolic control to a certain degree.     

Two large French pedigrees with non syndromic sensorineural deafness and the mitochondrial DNA T7511C mutation: evidence for a modulatory factor

Hearing impairment is the most frequent sensory defect in children, with a genetic basis in about 50% of cases. Several point mutations and deletions in mitochondrial DNA (mtDNA) have been identified in non-syndromic sensorineural hearing loss (NSSNHL). Beside the frequent A1555G mutation, a number of mutations in tRNAs have been reported recently, but their incidence remains unknown. We identified the T7511C mutation in the tRNASer(UCN) gene in two French families with isolated deafness. Maternal transmission was obvious in both. The 15 patients with hearing impairment exhibited a variable disease phenotype in terms of onset, severity, and progression. T7511C was present in all the patients screened. Homoplasmic and heteroplasmic levels were observed and did not correlate with the severity of the disease. T7511C was also present in 12 hearing offspring of the oldest deaf mothers, confirming the existence of modulatory factors. Our data suggest that this mtDNA mutation should be screened for in all cases of familial NSSNHL compatible with maternal transmission.