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Biomedical subjects

K M Marimuthu

Publications and source records attributed to K M Marimuthu.

12 recordsLinked to original sources
PubMed2003

Syndrome-related chromosome-specific radiation-induced break points of various inherited human metabolic disorders.

The frequency, distribution pattern and localisation of gamma radiation-induced break points on the chromosomes of patients with various inherited metabolic disorders were studied to detect: (i) whether the break point distribution following irradiation is random and proportional to the length or the DNA content of the chromosome, or non-proportionally distributed on their length and at times clustering to form hot spots on certain region of the chromosomes; and (ii) to find whether there exists a syndrome-related chromosome-specific pattern of radiation-induced break points. Lymphocyte cultures from patients of haemophilia, ichthyosis, Duchenne muscular dystrophy, retinitis pigmentosa and alpha-thalassemia, whose defective gene loci were located by DNA probe method, were subjected to 3Gy of gamma radiation at G(0). The chromosomal break point analysis was carried out on all the 23 types of chromosomes (excluding Y chromosome) using G banding and FISH painting. The exact location of the break points on G-banded chromosomes was identified using a semi-automated microscope densitometer system (Leitz MPV2). In normal individuals in all the chromosomes except the chromosome 1, a random distribution of break points proportional to their length based on their DNA content was observed. However, in all the syndromes studied a mixture of hypersensitive chromosomes with a non-random distribution pattern of chromosomal break points invariably clustering to form hot spots, and chromosomes with random distribution of break points proportional to their length were observed. The hypersensitive chromosomes and their hot spots were syndrome-specific.

Cells, Cultured↗
PubMed1993

Chromosomal break points in irradiated and ethyl methane sulphonate treated leucocytes of patients with Down syndrome.

Frequencies of chromosomal damage in the peripheral leucocytes of patients with Down syndrome, on exposure to gamma rays (2Gy) or ethyl methane sulphonate (EMS, 1x 10(-4) M), were assessed. Analysis of break points in the chromosomes of irradiated cells revealed a non-random occurrence. Six of the break points observed in EMS-treated cells were found to overlap with those recorded in irradiated cells. Thirteen break points observed were found to correlate with the location of cancer-specific break points and four of these coincided with the bands where oncogenes have been located. Two break points were localised to the same bands as that of known heritable fragile sites.

Chromosome Aberrations↗
PubMed1990

A genetic study of immunoglobulin E and atopic disease based on families ascertained through asthmatic children.

In order to investigate the modes of inheritance of serum immunoglobulin E (IgE) levels and atopic disease, serum IgE levels and data on allergic disease were obtained from 42 families ascertained through asthmatic children visiting an allergy clinic. Although the mean IgE levels were elevated (mean 637 U/ml), the prevalence of atopic disease in this population was surprisingly low. When the data were analyzed using complex segregation analysis, no major locus could be detected. Moreover, the polygenic heritability was unexpectedly small even though the correlation between serum IgE levels and the liability to atopic disease was around 0.4. Given this unusual set of findings, it is postulated that parasitic infections in this population have (in accordance with well-established results of parasitic disease) caused both elevated levels of serum IgE and a decreased prevalence of allergic disease with the possible masking of the various genetic components of serum IgE levels and atopic disease.

Asthma↗
PubMed1983

Association between the degree of mosaicism and the severity of syndrome in Turner mosaics and Klinefelter mosaics.

This study, based on the investigations carried on 82 cases of Turners of which 50 of them were mosaics and 85 cases of Klinefelters of which 70 of them were mosaics, is an attempt to explain the vast range of clinical variations observed in cytogenetically established Turner mosaics (45,X/46,XX) and Klinefelter mosaics (47,XXY/46,XY) in the light of the degree of mosaicism present in them. It was observed that the severity of the syndrome in Turner mosaics and Klinefelter mosaics increased with the relative increase in the abnormal cell line population.

Adult↗
PubMed1978

Origin of cells in human amniotic fluid cultures: ultrastructural features.

Two classes of cells can be subcultured from human amniotic fluid (F and AF). Ultrastructural features of these cultrued cells were determined using scanning and transmission electron microscopy with particular attention to extracellular material. Results obtained from these two cell types are compared to one another and to cultured human dermal fïbroblasts. The F-type cultures have an abundance of extracellular type i collagen fïbers, identical with cultured human dermal fïbroblasts. No type I collagen fïbers are seen in cultures of AF cells. Instead, fïne fïlamentous material is admixed with amorphous material adjacent to cell membranes where epithelial basement membrane glycoprotein has been localized. By scanning electron microscopy parallel arrays of cells are present at confluency of F cultures, typical of cultured dermal fïbroblasts. AF cultures show a much looser growth pattern at confluency. On the basis of accumulated evidence, we believe that F-type cells arise from fïbrous connective tissue and are fïbroblasts, whereas AF cells, the predominant type in early cultures used for prenatal genetic diagnosis, arise from fetal membranes and retain features of trophoblast.

Amniotic Fluid↗
PubMed1974

Computer-assisted analysis of chromosomal abnormalities: detection of a deletion in aniridia-Wilms' tumor syndrome.

A chromosome translocation, t(8p + ; 11q -), in a patient with aniridia and Wilms' tumor, appeared balanced by standard techniques, including trypsin banding. Computer analysis of optical microscope scanning profiles of chromosome pairs 8 and 11 revealed an interstitial deletion of the short arm of 8. Computer analysis coupled to the new banding techniques provides greater resolution for the detection of subtle chromosomal variations not recognized by banding methods alone.

Abnormalities, Multiple↗
PubMed1970

Radiobiological studies of plants orbited in Biosatellite II.

The Biosatellite II Tradescantia experiment probed the effects of the space environment on spontaneous and radiation-induced mutation rates and on cytological changes in Tradescantia clone 02. Thirty two young flowering plants arranged in a plastic housing with the roots immersed in nutrient solution were exposed to gamma radiation from an on-board 85 Strontium source during the two-day orbital flight. Unirradiated plants were flown in a package in the spacecraft behind a tungsten radiation shield and identical non-flight control packages (with and without irradiation) were maintained at the launch site. After retrieval of the spacecraft near Hawaii, samples of root tip, ovary and stamen tissues were collected. These and the intact plants were flown to the Brookhaven National Laboratory for observations on the following end points: somatic mutation, cell size, loss of reproductive integrity resulting in stunted stamen hairs, pollen grain mortality, frequency of micronuclei in pollen, disturbed mitotic spindle function and chromosome aberrations. Analysis of data on somatic mutation, cell size and chromosome aberration end points showed no significant differences between flight and non-flight samples. However, pollen abortion, frequency of micronuclei in pollen and loss of reproductive integrity (stamen hair stunting) showed increases associated with weightlessness in irradiated material. Root tip and microspore cells showed effects of disturbed mitotic spindle function in orbited plants both with and without irradiation. Clearly differences exist between flight and non-flight material and the significance and possible mechanisms for these effects are being studied in continuing non-flight tests.

Cell Division↗