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At least 991 records · Page 55Linked to original sources
PubMed1990

Role of somatic mutation in atherosclerosis.

Thus, plaque DNAs from two widely different classes of organisms exhibit similar molecular alterations, which are comparable to those previously described for a number of tumor DNAs. These findings represent the first direct demonstration that mutational events may be critical in the etiology of arteriosclerotic plaques.

Animals↗
PubMed1990

Multiple endpoints for somatic mutations in humans provide complementary views for biodosimetry, genotoxicity and health risks.

While monitoring people with multi-endpoint analysis is only just beginning, the indications of complementarity of these assays are already evident. Since two different tissue types are analyzed, effects of uneven exposure or tissue-specific sensitivities or development kinetics and persistence of each cell type can be addressed. The differing analytical techniques in determining variant cells lead to particular advantages for each assay procedure. The GPA assay can be performed rather quickly on small blood volumes (as little as 0.1 ml). A similar potential exists for the Hb assay, although sophisticated instrumentation development is still required to make this assay easily performable. Both the HPRT and HLA assays require long term tissue growth and many-fold larger (10-30 ml) blood samples. However, both the HPRT and HLA assays have the advantage that they select variant cells that contain nuclei, so that detailed characterization of their mutagenesis is possible using Southern blots, hybridization analysis, and gene sequencing. Since erythrocytes have no nucleic acids, so these effects cannot be measured using the GPA or Hb assay. Other differences between the assays are the target size, chromosomal location, and control signals. Each gene locus is on a different chromosome, with GPA, HLA and Hb genes on autosomes and HPRT on the X chromosome. The target size for GPA and HPRT are about 40kb, whereas HLA A locus is 5kb and the Hb target is one base. These differences should result in much different sensitivity to different mutagenic phenomena, such as radiation effects or different chemical effects. The multiple differences between assays that are designed to detect similar kinds of events occurring in vivo in humans leads us to conclude that all these assays could well be performed on the same blood samples, and the information gained would be much more than the separate assays could yield. Biodosimetry and estimation of cancer initiation could become realistic goals instead of simply significant desires.

Aging↗
PubMed1985

Somatic mutations in the variable region of the lambda 2 chain of M315 suppression of antibodies to the idiotype of M315.

BALB/c mice immunized with purified BALB/c myeloma protein M315 (alpha, lambda 2) produce anti-idiotypic antibody directed predominantly to a combinational (VH-315 + VL-315) determinant(s) of the M315 paratope (Sirisinha and Eisen, 1971; Tungkanak and Sirisinha, 1976). We examined whether the unique B cell response is influenced by pretreatment of mice with fragments or chains derived from M315 before immunization with M315. Intravenous (i.v.) injection of the Fv-315 fragment (VH-315 + VL-315) into normal BALB/c mice seven days before immunization with M315 resulted in marked suppression of anti-M315 idiotype antibodies. Studies on the structural requirement for suppression indicated that VL-315, but not VH-315, is involved. Structural comparison with a defined lambda 2 light (L) chain suggested that three contiguous amino acid residues in the third hypervariable loop of the variable (V) domain of the L chain of M315 are important for down-regulation of production of antibodies to the M315 idiotype.

Animals↗
PubMed1989

[Incidence of somatic mutations of the lymphocytes in subjects working in an environment with cancer risk].

A total of 417 individuals were examined by the Strauss-Albertini method, which is useful to detect the lack of hypoxanthin-guanine-phosphoribosil-transferase (HPRT) located on the X-chromosome. The damage of this locus leads to the loss of the sensitivity of the T-lymphocytes to 6-thioguanine (TG) therefore in the presence of this antimetabolite (TG) the cells will respond to the lectin's (phytohaemagglitinine: PHA) growth stimulatory effect. This defect in the cells can cause mutation, making the cells to be resistant against TG-treatment and during their blastogenesis they will be able to incorporate 3 (H)-thymidine. The number of these labeled cells will give the frequency of the mutant (TG-resistant) cells. The results showed a significant elevation in the number of TG-resistant lymphocytes among uranium miners and among industrial workers exposed to different mutagenic or carcinogenic chemicals when compared to the negative controls. The mutation frequency was elevated also among primary lung cancer patients (positive controls) up to the level measured among industrial workers.

Air Pollutants, Occupational↗
PubMed1989

Detection of somatic mutations at the glycophorin A locus in erythrocytes of atomic bomb survivors using a single beam flow sorter.

A modified method was developed for measuring the frequency of variant erythrocytes at the glycophorin A locus using a single beam cell sorter (SBS). Fluorescein- or phycoerythrin-labeled monoclonal antibodies specific for the M or N glycophorin A alleles were used for the SBS assay. To prevent contamination of nucleated cells in the sorting windows, the nucleated cells in the fixed erythrocyte sample were stained with propidium iodide before flow sorting. Blood samples were obtained from atomic bomb survivors who were heterozygous for the MN blood type, and the frequencies of the hemizygous and homozygous variant of the M or N glycophorin A allele were measured by the SBS. For the three types of variants, hemizygotes for M and N allele (Nø and Mø) and homozygotes for M allele (MM), the variant frequency measured by the SBS correlated well with that previously determined by a dual beam cell sorter. Variant frequencies of the Nø, Mø, and MM cell types in atomic bomb survivors determined by SBS measurements were found to increase with radiation dose (DS86, kerma) as well as with the frequency of chromosome aberrations in lymphocytes.

Alleles↗