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Biomedical subjects

J Samson

Publications and source records attributed to J Samson.

At least 37 records · Page 2Linked to original sources
PubMed1988

Retinoid-binding proteins in human oral mucosa.

Vitamin A affects epithelial differentiation and growth via at least 3 different binding proteins. The specific delivery of extracellular retinol to target cells is performed by plasma retinol-binding protein (RBP) while cellular retinol- and retinoic acid-binding proteins (CRBP and CRABP) are implicated in the cellular action of the 2 natural retinoids. We have studied the levels of these 3 binding proteins by gel filtration and polyacrylamide electrophoresis in human oral mucosa, epithelium and chorion and compared it to those found in keratinizing human epidermis. The levels of CRABP in oral epithelium were markedly higher (about 4 times) than that of epidermis whereas CRBP was in a similar amount in epithelium chorion, dermis and epidermis. RBP with preserved affinity for retinol, was present in the epithelium of oral mucosa whereas only degraded RBP was detected in epidermis. These results suggest (i) a higher specific retinol delivery and (ii) a distinct cellular metabolism of retinoic acid in the oral epithelium as compared with epidermis. Since cornification occurs when keratinocytes are deprived of retinol, it might be that our observations are linked to the absence of cornification in the human oral mucosa. Further, high levels of CRABP in mucosal epithelium might have therapeutical implications because the synthetic retinoids used in human therapy bind to CRABP.

Adolescent↗
PubMed1988

Racial differences in sports performance.

The purpose of this paper is twofold: (a) to present data on racial differences in sport performance and (b) to comment briefly on theories, hypotheses and studies, whether they be biological, psychological or sociological in nature, that have attempted to explain the observed differences. Available data are mainly drawn from studies focusing on American professional sports. The results indicate that Afro-American athletes largely dominate the sport scene in a few sports and across a wide range of performance indicators. Although it is impossible at this time to conclude with satisfaction on the causes of racial differences, sociological explanations seem best to explain the observed performance differentials.

Black People↗
PubMed1987

Experimental infections of free-ranging Rocky Mountain bighorn sheep with lungworms (Protostrongylus spp.; Nematoda: Protostrongylidae).

Twelve free-ranging Rocky Mountain bighorn lambs (Ovis canadensis canadensis), each exposed experimentally to 125-1,000 infective third-stage larvae of Protostrongylus stilesi and P. rushi, shed significantly more first-stage larvae in their feces than did control lambs, but showed no clinical signs of illness and had equivalent summer and overwinter survival as control lambs. Two adult ewes, each exposed to 925 infective larvae, showed no increase in numbers of first-stage larvae in their feces; both survived at least 14 mo postexposure. Experimentally exposed lambs did not differ from control lambs in numbers of larvae in their feces in the following summer. Three experimental lambs had 313-402 adult P. stilesi and 0-97 adult P. rushi on necropsy; two control lambs had 255 and 270 P. stilesi and no P. rushi. The presence of these numbers of lungworms did not appear to be sufficient to precipitate lungworm pneumonia in bighorn lambs under the conditions of this study.

Animals↗
PubMed1985

Induction of differentiation and inhibition of DNA methylation in HL-60 myeloid leukemic cells by 5-AZA-2'-deoxycytidine.

The effects of 5-AZA-2'-deoxycytidine (5-AZA-CdR) on the induction of morphological and biochemical differentiation and inhibition of DNA methylation of human HL-60 myeloid leukemic cells were investigated. 5-AZA-CdR at concentrations of 0.1-1 microgram ml-1 for 48-h exposure produced significant morphological differentiation of HL-60 leukemic cells to a more mature phenotype, augmented the cell surface marker (OKMI) for mature granulocytes/monocytes and also increased the superoxide anion production. Under these same conditions 5-AZA-CdR inhibited the synthesis of 5-methylcytosine in DNA suggesting that there is a correlation between the induction of differentiation and inhibition of DNA methylation. At concentrations of 5-AZA-CdR that inhibit DNA methylation there was a marked decrease in colony-formation suggesting that the antileukemic action of this analog is related to the methylation of DNA.

Antineoplastic Agents↗
PubMed1985

[Focal epithelial hyperplasia: first cases in Switzerland and review of the literature].

Three cases of 'focal epithelial hyperplasia' (FEH) of the oral mucosa observed for the first time in Switzerland are reported. The patients were of Turkish and North African extraction. The lesions of FEH were multiple, painless, located at various sites of the oral mucosa including the tongue, in the form of either soft papules or hard nodules. Evidence of a human papilloma virus origin was ascertained. Among the 1,067 cases reported in the literature and reviewed for this study, this condition has been described to occur among American Indians, Eskimos and Cape Coloureds; also in Israeli and European cases the disorder was often reported in individuals of Turkish or North African extraction.

Adult↗
PubMed1985

[Osteoblastoma of the jaws. 2 cases and a review of the literature].

The authors report on two cases of osteoblastoma: one of the maxilla in a twenty-two year old woman, the other of the mandible in a thirty-eight year old woman. In the two cases, the lesions were discovered after a systematic X-ray examination and they were treated by curettage. To date, sixty-seven cases of jawbone osteoblastoma and eleven cases of osteoid osteoma, a lesion which resembles and is perhaps similar to the osteoblastoma, have been reported in the literature. The authors develop the differential diagnosis and study the relationship between these two varieties of a same tumor or pseudo-tumor.

Adolescent↗
PubMed1984

Cell cycle effects and cellular pharmacology of 5-aza-2'-deoxycytidine.

The cytotoxic action of 5-aza-2'-deoxycytidine (5-AZA-CdR) in synchronized cells and logarithmic- and plateau-phase cultures of EMT6 murine tumor cells was investigated. 5-AZA-CdR produced a greater cell kill of S phase cells than of cells in G1 phase. Cells in the logarithmic phase of growth were more sensitive to the cytotoxic effects of 5-AZA-CdR than cells in the plateau phase of growth. These results indicate that 5-AZA-CdR produces a preferential kill of cells in the S phase of the cell cycle. 5-AZA-CdR did not block the cell cycle progression of cells into S phase. The survival curve of EMT6 cells exposed to 5-AZA-CdR suggests that the cytotoxic action of this analogue is not self-limiting. The mutagenic activity of 5-AZA-CdR was investigated using induction of 6-thioguanine resistance in Chinese hamster ovary cells. 5-AZA-CdR was not a detectable mutagen in this assay system.

Animals↗
PubMed1984

Comparison of the antileukemic activity of 5-AZA-2'-deoxycytidine, 1-beta-D-arabinofuranosylcytosine and 5-azacytidine against L1210 leukemia.

The antineoplastic activity and effect on DNA synthesis and DNA methylation of 5-aza-2'-deoxycytidine (5-AZA-CdR), 1-beta-D-arabinofuranosylcytosine (ARA-C), and 5-azacytidine (5-AZA-CR) on L1210 leukemic cells were compared. At equimolar concentrations 5-AZA-CdR produced greater growth inhibition and more cytotoxicity against the L1210 cells than either ARA-C or 5-AZA-CR. ARA-C, but not 5-AZA-CdR or 5-AZA-CR, produced a potent inhibition of DNA synthesis in the L1210 cells. 5-AZA-CdR and 5-AZA-CR, but not ARA-C, inhibited DNA methylation with 5-AZA-CdR being a more effective inhibitor than 5-AZA-CR. At maximum tolerated dose, 5-AZA-CdR produced a much greater increase in life span of mice with L1210 leukemia than ARA-C or 5-AZA-CR. These in vitro and in vivo studies indicate that 5-AZA-CdR is a more potent antineoplastic agent against L1210 leukemic cells than either ARA-C or 5-AZA-CR.

Animals↗
PubMed1982

Combinational chemotherapy of L1210 and L1210/ARA-C leukemia with 5-AZA-2'-deoxycytidine and beta-2'-deoxythioguanosine.

The in vitro and in vivo antineoplastic activity of 5-AZA-2'-deoxycytidine (5-AZA-CdR) and beta-2'-deoxythioguanosine (TGdR) on L1210 and L1210/ARA-C (resistant to cytosine arabinoside) leukemic cells was investigated. 5-AZA-CdR was a very potent cytotoxic agent against the L1210 leukemia cells. This analogue was inactive against L1210/ARA-C leukemic cells because these cells lack deoxycytidine kinase, the enzyme that converts 5-AZA-CdR to its active nucleotide form. TGdR was a potent cytotoxic agent to both L1210 and L1210/ARA-C leukemic cells. In mice which were injected simultaneously with both L1210 and L1210/ARA-C leukemic cells, the drug combination of 5-AZA-CdR plus TGdR had a very potent antineoplastic activity and produced long-term survivors. Either agent alone did not produce any long-term survivors in the mice with L1210 and L1210/ARA-C leukemia. This experimental model indicates that 5-AZA-CdR plus TGdR is an interesting drug combination for the treatment of leukemia with drug-resistant cells.

Animals↗
PubMed1981

Neutrophil function in Bartter's syndrome.

Bartter's syndrome is a state associated with hyperprostaglandinemia and high urinary excretion of prostaglandin derivatives. Because of numerous reports on prostaglandins acting as local modulators of the immune system, we have studied parameters of phagocytic function and of cellular and humoral immunity in four patients with this disease. An augmentation in chemotaxis was identified in Bartter's syndrome neutrophils. Despite some minor deviations in other parameters measured, no other gross derangement in immune function could be identified.

Bartter Syndrome↗
PubMed1979

[Early detection of pemphigus vulgaris: role of the dentist].

Means to detect pemphigus vulgaris at an early stage are described. Its grave evolution in absence of treatment makes an early diagnosis imperative. The first signs are frequently localized in the oral mucosa and sometimes the disease remains confined to this mucosa only. Efficient and early therapy may favourably influence the course of disease, and the dentist is in a prime position to detect the characteristic lesions.

Acantholysis↗