PubMed Health⌕ Search

Biomedical subjects

C Louis

Publications and source records attributed to C Louis.

124 records · Page 7Linked to original sources
PubMed1977

[Familial nephropathy with retinitis pigmentosa and peripheral dysostosis].

The paper reports two siblings, 6 and 3 3/4 years old, with a congenital nephropathy (nephronophthisis), retinitis pigmentosa, heart failure and peripheral dysostosis. The severe histological changes of the kidneys with tubular atrophy and interstitial fibrosis caused the death of the older sister at the age of 7 years. The symptoms of our patients are discussed in comparison to the syndrome described by MAINZER et al.

Bone Diseases, Developmental↗
PubMed1975

[Report of pheochromocytoma in childhood (author's transl)].

This paper reports the results and specific variations in diagnostic and therapy of pheochromocytoma in childhood. Two patients aged 10 and 12 years are described. Previous reports about 155 cases are summarized in respect to localization and frequency of occurrence. In our experience the catheterization of the vena cava is a small-risk method to localize the tumor and to obtain informations about the amount and type of cathecholamines. The value and limits of the diagnostic procedure - until now seldom used in children - are mainly discussed. The improvement of symptoms and the marked circulatory changes by the treatment with the alpha-adrenergic blocking agent Dibencyline are described. The histological differentiation between benign and malign growth proves to be uncertain.

Adrenal Gland Neoplasms↗
PubMed1970

Respiratory metabolism of a "petite negative"yeast Schizosaccharomyces pombe 972h-.

The respiratory metabolism of Schizosaccharomyces pombe 972h(-), a fission, haplontic, "petite negative" yeast, was studied. Glucose and glycerol are good growth substrates and are oxidized under appropriate conditions. l-Lactate, ethanol, malate, and succinate are oxidized but are poor substrates for growth. d-Lactate and pyruvate are neither oxidized nor used for growth. Limited growth was observed under anaerobic conditions. The addition of 0.3% KNO(3) to a rich medium relieves the oxygen requirement. A continuous increase of cell respiration during growth on repressive concentration of glucose was observed, suggesting the presence of glucose repression of respiration. Reduced nicotinamide adenine dinucleotide (NADH), succinate, alpha-glycerophosphate, and ascorbate plus tetramethyl-p-phenylenediamine are oxidized by a mitochondrial fraction. NADH and succinate oxidations are inhibited by antimycin A and NaCN but not by rotenone, suggesting the absence of the phosphorylation site I and the presence of sites II and III. The effects of several mitochondrial inhibitors on growth and respiration indicate that the requirement of an oxidant for growth is related neither to the functioning of the respiratory electron transport chain nor to the formation of respiratory energy. The previously suggested correlations between the nonviability of vegetative "petites" mutants, the absence of repression of respiration by glucose, and the incapacity to grow under anaerobic conditions are thus not strictly valid for S. pombe.

Acetates↗
PubMed1970

Segregational respiratory-deficient mutants of a "petite negative" yeast Schizosaccharomyces pombe 972h-.

No viable respiratory-deficient mutants of Schizosaccharomyces pombe 972h(-) could be obtained by acriflavine and ethidium bromide treatments. These mutagens induce 15 to 70% of microcolonies which, after a growth-lag of a few days, further develop into normal, respiratory-competent colonies. These results suggest that unstable petites were induced. Segregational respiratory-deficient mutants resistant to cobalt sulfate inhibition were isolated. Some of these strains are deficient in cytochrome a + a(3) and respire at low rates. The morphology of their mitochondrial membranes is modified: either the cristae are absent or they show aberrant concentric or tubular structures. Segregational mutants resistant to the respiratory inhibitors, 2,4-dinitrophenol or decamethylene diguanidine, were obtained. Neither mitochondrial structure nor function seems to be modified in these mutants. A segregational mutant resistant to benzimidazole inhibition does not grow on glycerol, although neither growth on glucose nor respiration appear to be affected.

Acridines↗
PubMedDate not supplied

Drosophila melanogaster as an experimental host for study of multiplication and biology of the mycoplasma inducing the "lethargy of coleoptera".

The mulitplication of the mycoplasma responsible for the "lethargy of coleoptera" on a laboratory host, Drosophila melanogaster, was obtained on the first passage. Independant series of successive passages on D. melanogaster were performed without any apparent modifications of the properties of the microorganism. Pathogenicity for its natural host Melolontha melolontha was retained. The different forms of mycoplasma observed lead us to propose a probable cycle of development, composed of a succession of globular and rod-shaped bodies, these later being often sinuous. The infected Drosophila flies presented a reduced life span and fertility. Infection of the cephalic nervous system seems to be responsible for death. Horizontal transmission of the microorganism was not observed.

Animals↗
PubMedDate not supplied

[Importance of a thymus dysfunction in the pathophysiology of type 1 diabetes].

The autoimmune nature of the diabetogenic process and the major contribution of T lymphocytes stand now beyond any doubt. However, despite the identification of the three major type 1-diabetes-related autoantigens (insulin, GAD65 and phosphatase IA-2), the origin of this immune dysregulation still remains unknown. More and more evidence supports a thymic dysfunction in the establishment of central self-tolerance to the insulin family as a crucial factor in the development of the autoimmune response selective of pancreatic insulin-secreting islet beta cells. All the genes of the insulin family (INS, IGF1 and IGF2) are expressed in the thymus network. However, IGF-2 is the dominant member of this family first encountered by T cells in the thymus, and only IGFs control early T-cell differentiation. IGF2 transcription is defective in the thymus in one animal model of type 1 diabetes, the Bio-Breeding (BB) rat. The sequence B9-23, one dominant autoantigen of insulin, and the homologous sequence B11-25 derived from IGF-2 exibit the same affinity and fully compete for binding to DQ8, one class-II major histocompatibility complex (MHC-II) conferring major genetic susceptibility to type 1 diabetes. Compared to insulin B9-23, the presentation of IGF-2 B11-25 to peripheral mononuclear cells (PBMCs) isolated from type 1 diabetic DQ8+ adolescents elicits a regulatory/tolerogenic cytokine profile (*IL-10, *IL-10/IFN-g, *IL-4). Thus, administration of IGF-2 derived self-antigen(s) might constitute a novel form of vaccine/immunotherapy combining both an antagonism for the site of presentation of a susceptible MHC allele, as well as a downstream tolerogenic/regulatory immune response.

Autoantigens↗
PubMedDate not supplied

[Experimental infection of an invertebrate cell line with a mollicute-like procaryote inducing the "lethargy of coleoptera" (author's transl)].

In vitro multiplication of a pathogenic intravacuolar mollicute-like procaryote from Melolontha melolontha L. was experimentally obtained in an insect cell line. The elongated and pleomorphic forms observed in the insect-host are reproduced in cell cultures. A third peculiar giant form is missing, showing that it does not play any role in the multiplication of the germ. The intrinsic potentialities of the germ are maintained during the successive passages, as proved by reinfection of the insect and by immunology. The original syndrome including the giant form is reproduced in the insect. The immunserum prepared from the wild germ isolated by density gradient is positive with the in vitro mollicute. The germs are intravacuolar, both in the cultured cells and in the insect host. Clearly the microorganism multiplies within the vacuoles. A cytopathogenic effect is noticed in the cultured cells overcrowed with germs. The germs become extracellular when they are released in the culture medium by disaggregation of the cell membranes. It seems that this work shows the first model of an intravacuolar mollicute-like procaryote experimentally multiplied in cultivated cells.

Animals↗
PubMedDate not supplied

[Cytochemical and freeze-etching studies of the ultrastructure of a Rickettsiella in a crustacean (author's transl)].

Several characteristics of the intracellular cycle of Ricketsiella are elucidated, particularly regarding the envelope and the cytoplasm of dense forms (elementary bodies) as well as the proteinic inclusions of giant bodies. Cleavage faces have been displayed by freeze-etching, both at the level of cell wall and of plasma membrane. Their characteristics approach those of Gram-negative bacteria and are pratically common to all the stages. Appearance and significance of a polysaccharidic cement joining the outer membrane of the cell wall to the inner membrane (plasma membrane) in the dense forms are discussed. The arrangement of ribosomes and the structure of the nucleoid are described. A 6 nm lattice periodical structure is shown in the proteinic inclusion. Significance of these data for a classification of Rickettsiella and chlamydias is discussed.

Animals↗