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Biomedical subjects

R Nicolas

Publications and source records attributed to R Nicolas.

At least 19 recordsLinked to original sources
PubMed2001

Cerebellar gliomas in infants: specificity, pathology, and outcome.

Cerebellar gliomas (CGs) in children are generally associated with a favorable outcome; however, data regarding these tumors in very young children are scarce. We report on our experience with CGs in children less than 3 years old at surgery, compared with a second group older than 3 years. From 1991 to 1996, we operated on 7 children with CGs in the first group and 43 in the second. Psychomotor delay and regression were the first symptoms in 3 cases, and 3 had macrocrania. The tumor was totally removed in all cases. One child died intraoperatively of air embolism and subdural bleeding. Three had malignant tumors (grade 3 or 4). There was no operative mortality or malignancy in the second group of patients. With a mean follow-up of 33 months, all survivors in the first group are disease-free, with no or minimal symptoms, and attend normal schools. The clinical, surgical, and pathological features suggest that children under 3 years of age represent a specific subgroup of CGs.

Adolescent↗
PubMed1990

[Effect of treatment with clindamycin, erythromycin, rifamycin or gentamicin on the ingestion capacity of peritoneal macrophages in mice].

The effect of treatment with clindamycin, erythromycin, rifamycin and gentamicin on the ingestion capacity of the mouse peritoneal macrophage was studied. Female six-eight week old OF1 mice were treated with minimum and maximum doses clinically used for the different antibiotics (15 and 40 mg/kg/day of clindamycin, 15 and 57.5 mg/kg/day of erythromycin, 10 and 30 mg/kg/day of rifamycin, 3 and 6 mg/kg/day of gentamicin). Two treatment periods of 72 hours and one week were assayed for each antibiotic-dose combination. Antibiotic was administered twice daily, every twelve hours. Twelve hours after the last dose was given, macrophages were obtained through peritoneal lavage and a kinetic study of Candida albicans blastospore ingestion was made. One week treatment with 15 mg/kg/day and 72 hours treatment with 57.5 mg/kg/day of erythromycin produced a significant ingestion enhancement whereas one week treatment with 57.5 mg/kg/day of erythromycin and all treatments with gentamicin gave rise to an ingestion depression. 72 hours treatment with 15 and 40 mg/kg/day and one week treatment with 15 mg/kg/day of clindamycin, 15 mg/kg/day of erythromycin and 10 and 30 mg/kg/day of rifamycin did not modify macrophage ingestion capacity. One week treatment with 40 mg/kg/day of clindamycin and 10 and 30 mg/kg/day of rifamycin gave rise to an acceleration of the ingestion process.

Animals↗
PubMed1989

Relationship between the production of interferon-alpha/beta and interferon-gamma during acute toxoplasmosis.

Acute toxoplasmosis was induced in mice, and interferon (IFN) production in serum and by spleen cells was evaluated during the infection period. Interferon was characterized by acid-treatment and anti-IFN-alpha/beta neutralization. In order to verify the correlation between the unusual aspects of the IFN production and the induction of immunosuppression, splenocyte mitogen responsiveness was investigated concomitantly to IFN synthesis. The activity of Toxoplasma-induced serum IFN-alpha/beta increased gradually throughout all post-infection days, but IFN-gamma was not detected in the systemic circulation at any time during the infection. It was also observed that IFN-alpha/beta production and the capacity to produce IFN-gamma by spleen cells were closely and inversely correlated. As the infection progressed, more IFN-alpha/beta was produced, and the ability of spleen cells to produce IFN-gamma decreased. The observation that Toxoplasma-infected mice were concomitantly immunosuppressed (as documented by mitogen unresponsiveness and defective IFN-gamma production) in direct correlation to IFN-alpha/beta production, suggests that such IFN-alpha/beta production is an important factor associated with acute toxoplasmosis-induced immunosuppression.

Acute Disease↗
PubMed1989

Effect of erythromycin treatment on specific immunologic response in mice.

Six week old Swiss mice were sensitized by subcutaneous injection of 10(7) sheep red blood cells without adjuvant. One hour after sensitization, the mice were treated with erythromycin lactobionate for ten days. The minimal (15 mg/kg/day) and maximal (57 mg/kg/day) doses clinically used were assayed. The daily dose of erythromycin was administered intraperitoneally, in two injections, one every 12 hours. The kinetics of delayed type hypersensitivity reaction, measured by means of the foot-pad test, was evaluated by challenging different groups of fourteen mice with an eliciting dose of 10(8) SRBC injected into the foot-pad on days 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 after sensitization. Total and 2-mercaptoethanol resistant haemagglutinating antibody titres were determined in sera obtained from mice immediately after measuring the delayed type hypersensitivity reaction. Treatment with maximal erythromycin dose gave rise to a significant enhancement of the cellular immune response, and also to an acceleration of the humoral antibody response. On the other hand, treatment with minimal erythromycin dose gave rise to a slight depression of the immune cellular response and also to a depression of the antibody production at the beginning of the humoral response.

Animals↗
PubMed1988

[A new sensitivity test for substances used as antiseptics or disinfectants. I. Biological studies].

In this first article, the authors present a fast method of determining the bactericide and bacteriostatic power of the germs, based on the disparition of the succino-dehydrogenase activity of a bacterium, objectified by a neotetrazolium chloride reaction. This reaction allows a colorimetric qualitative and quantitative determination of the activity of a preparation and the duration of its contact with the bacteria. This method allows a study in electronic microscopy which will be published in a second article.

Anti-Infective Agents, Local↗
PubMed1981

[The rising rate of complementary examinations in suspected neurinoma of the VIIIth cranial nerve (author's transl)].

E.N.T. specialists are obsessed by the diagnosis of neurinoma of the VIIIth cranial nerve. Yet none of the conventional otological or radiological examinations is entirely reliable. In a major centre all otological and radiological investigations can be carried out systematically, but diagnosing the disease with a minimum of examinations is important, would it only be to decide which patients should be referred to the neuroradiologist. Complementary otological and neuroradiological explorations are therefore requested in ever increasing number on the basis of initial symptoms and results of the first examination. Among exploratory methods, CT with injection of air occupies a prominent place as it enables neurinomas located inside the internal auditory canal to be diagnosed at an early stage.

Audiometry↗
PubMed1978

Left ventricular function in tetanus: influence of therapy.

Nine patients hospitalized for tetanus were studied under the same protocol which included two haemodynamic studies with a preload trial (PLT). The first being made during therapy (diazepam barbiturate association), on the sixth day of hospitalisation, and the second one after recovery. The comparison of the results shows that before PLT the mean arterial pressuure (MAP) is significantly increased (p less than 0.05) in patients after recovery in comparison to the same patients undergoing therapy. After PLT there is no significant difference between the two groups. Lastly, the variation of the left ventricular function points under PLT shows no significant difference between patients during therapy and after recovery. These results suggest that the diazepamphenobarbital combination does not alter the left ventricular function of the patients undergoing this therapy during tetanus.

Diazepam↗
PubMed1975

[Complete atrioventricular block in bacterial endocarditis].

A case of bacterial endocarditis complicated by complete auriculoventricular block is reported. The pathological findings and data from previously reported cases point to the fact that this complication is generally indication of very extensive cardiac and valvular damage. Surgery, although dangerous, should be attempted in the circumstances.

Aged↗