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Biomedical subjects

A N Moshell

Publications and source records attributed to A N Moshell.

28 records · Page 2Linked to original sources
PubMed1982

Lymphoblastoid lines and skin fibroblasts from patients with tuberous sclerosis are abnormally sensitive to ionizing radiation and to a radiomimetic chemical.

Lymphoblastoid lines, derived by transforming peripheral blood lymphocytes with Epstein-Barr virus, and skin fibroblast lines were established from two patients with tuberous sclerosis. The number of viable lymphoblastoid cells was determined by their ability to exclude the vital dye trypan blue after their irradiation with x-rays or 254 nm ultraviolet light. The growth of fibroblasts was determined by their ability to form colonies after treatment with the radiomimetic, DNA-damaging chemical N-methyl-N'-nitro-N-nitrosoguanidine. The tuberous sclerosis lymphoblastoid lines were hypersensitive to x-rays but had normal sensitivity to the ultraviolet radiation. The tuberous sclerosis fibroblast lines were hypersensitive to the N-methyl-N'-nitro-N-nitrosoguanidine. The hypersensitivity of tuberous sclerosis cells to x-rays and to N-methyl-N'-nitro-N-nitrosoguanidine is believed to reflect defective repair of DNA damaged by these agents and may provide the basis for in vitro, including prenatal, diagnostic tests for tuberous sclerosis.

Adolescent↗
PubMed1981

A simple and rapid method for evaluating the survival of xeroderma pigmentosum lymphoid lines after irradiation with ultraviolet light.

A simple, rapid, and reproducible test has been developed to measure the viability of cells after irradiation with ultraviolet light (UV). Epstein-Barr virus-transformed lymphoid lines, derived from patients with xeroderma pigmentosum (XP), were irradiated with UV, and the post-UV viability of the lymphoid lines was determined by the trypan blue dye exclusion method. The relative post-UV survival of the patients' lymphoid lines was similar to the relative post-UV survival of the patients' fibroblast strains.

Cell Division↗
PubMed1981

The post-UV colony-forming ability of normal fibroblast strains and of the xeroderma pigmentosum group G strain.

In xeroderma pigmentosum, an inherited disorder of defective DNA repair, post-UV colony-forming ability of fibroblasts from patients in complementation groups A through F correlates with the patients' neurological status. The first xeroderma pigmentosum patient assigned to the recently discovered group G had the neurological abnormalities of XP. We have determined the post-UV colony-forming ability of cultured fibroblasts from this patient and from 5 more control donors. Log-phase fibroblasts were irradiated with 254 nm UV light from a germicidal lamp, trypsinized, and replated at known densities. After 2 to 4 weeks' incubation the cells were fixed, stained and scored for colony formation. The strains' post-UV colony-forming ability curves were obtained by plotting the log of the percent remaining post-UV colony-forming ability as a function of the UV dose. The post-UV colony-forming ability of 2 of the 5 new normal strains was in the previously defined control donor zone, but that of the other 3 extended down to the level of the most resistant xeroderma pigmentosum strain. The post-UV colony-forming ability curve of the group G fibroblasts was not significantly different from the curves of the group D fibroblast strains from patients with clinical histories similar to that of the group G patient.

Cells, Cultured↗
PubMed1980

Radiosensitivity in Huntington's disease: implications for pathogenesis and presymptomatic diagnosis.

Huntington's disease (HD) is a dominantly inherited fatal disorder characterised by premature death of nerve cells. Cultured lymphocyte lines from four patients with HD were abnormally sensitive to the lethal effects of X rays, as were lines from two of five subjects at risk for HD. The hypersensitivity is specific for ionising radiation, since HD lines had normal survival after exposure to ultraviolet radiation. The hypersensitivity, which may reflect an inherited defect in DNA repair, provides the basis for a presymptomatic diagnostic test for the disease.

Cell Survival↗
PubMed1979

DNA repair processes protect human beings from premature solar skin damage: evidence from studies on xeroderma pigmentosum.

The repair of DNA damage by ultraviolet light is defective in the hereditary disease xeroderma pigmentosum. A deoxyribonucleotide excision-proficient form and several excision-deficient forms of xeroderma pigmentosum have been identified. Premature solar skin damage develops in all xeroderma pigmentosum patients. Some patients also have neurological abnormalities caused by premature death of nerve cells. This abnormal aging of the central nervous system and of sun-exposed skin appears to be the result of the abnormal DNA repair processes. Clinical, biological, and physicochemical studies on DNA-repair-dependent processes and on the DNA repair defects in xeroderma pigmentosum are elucidating the mechanisms by which such abnormal aging is prevented in normal human beings.

Adult↗
PubMed1977

Photoprotection in erythropoietic protoporphyria: mechanism of photoprotection by beta carotene.

Erythropoietic protoporphyria is a genetic disease caused by the accumulation of protoporphyrin IX. This molecule absorbs 400-nm light and its presence is at times associated with severe cutaneous photosensitivity. The only effective treatment for this disease is oral administration of beta carotene. Several possible mechanisms of photoprotection by beta carotene were investigated using the photohemolysis of red blood cells as an in vitro model. Additional studies were done in an in vivo model which involves lethal hematoporphyrin photosensitization of white mice. The photoprotective effects of beta carotene were compared with those of alpha tocopherol, an agent which possesses some but not all the properties that have been implicated in explaining the known effectiveness of beta carotene. In the photohemolysis model, both compounds demonstrated partial protection. In hematoporphyrin-photosensitized mice, tocopherol showed some protection at high doses, while beta carotene showed greater protection at lower concentrations. Although these results suggest that photoprotective was due to free radical scavenging or singlet oxygen quenching, properties common to both agents, they do not rule out the possible role of 400-nm light absorption, a property of beta carotene alone.

Animals↗
PubMed1976

The transport of alpha-tocopherol and beta-carotene in human blood.

The concentrations and distributions of major lipids (cholesterol, phospholipid, and triglyceride), tocopherol and carotenoids were determined in the plasma lipoprotein fractions (VLDL, LDL, and HDL) of (1) normal human subjects, (2) patients with hyperlipoproteinemia, and (3) patients with erythropoietic protoporphyria treated with oral beta-carotene and/or alpha-tocopherol. The distribution of tocopherol (in percent) was most closely correlated with the distribution of total lipids in the individual lipoproteins, while the major portion of beta-carotene was present in the low density lipoproteins, irrespective of the lipid distribution in the lipoproteins (except for one subject with hyperchylomicronemia). The alpha-tocopherol and beta-carotene concentrations of plasma and RBC in patients treated with tocopherol and carotene were determined periodically for a one-year period. Plasma and RBC tocopherol concentrations showed a rapid, parallel increase in response to tocopherol supplementation. In contrast, the plasma and RBC carotene concentrations showed a much slower and nonparallel increase in response to carotene administration. When carotene supplementation was stopped, the elevated carotene levels in both plasma and RBC persisted for several months; the elevated plasma carotene level persisted longer than the raised RBC carotene levels. These results suggest that alpha-tocopherol and beta-carotene are transported differently in the circulation and that the tissue storage and mobilization of these compounds are different.

Adult↗