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Biomedical subjects

S Pathak

Publications and source records attributed to S Pathak.

At least 145 records · Page 8Linked to original sources
PubMed1979

A human breast adenocarcinoma with chromosome and isoenzyme markers similar to those of the HeLa line.

Pleural effusion was obtained from a 51-year-old black woman who had breast adenocarcinoma and had received chemotherapy and radiation therapy after a radical mastectomy. Cytogenetic and isoenzymic analyses of the cells were performed within a few hours of obtaining the sample. Similar analyses were also done with a cell line established from this effusion. The stemline chromosome number was 35, one of the lowest in human neoplasms. In addition to a marker chromosome involving 1q, which is common in human breast tumors, we found several other marker chromosomes whose G-banding patterns were similar to some of the typical HeLa markers. Genetic signature analysis of 15 isoenzyme loci revealed that 13 were identical to those of HeLa. Both HeLa and the cell line described here express glucose-6-phosphate dehydrogenase type a, yet they were derived from heterozygotic individuals (ab). Our data indicate the necessity to extensive cytogenetic and biochemical analysis before conclusions are made that cell lines are actually intercell-line contaminants.

Adenocarcinoma↗
PubMed1978

Responses of mammalian metaphase chromosomes to endonuclease digestion.

Digestion of fixed metaphase chromosomes by endonucleases (micrococcal nuclease and DNase II) under optimal digestion conditions followed by Giemsa staining produces sharp banding patterns identical to G-bands. In 3H-thymidine labeled, synchronized metaphase cells of the chinese hamster (CHO line), the band induction is accompanied by the removal of DNA. The single strand specific nuclease S1 and DNase I do not produce such banding patterns.

Animals↗
PubMed1978

An electron-microscopic study of avirulent and virulent Semliki forest virus in the brains of different ages of mice.

Ultrastructural studies of brains infected with avirulent and virulent strains of Semliki forest virus (SFV) were performed in 2-7, 14, 19, and 21-28 day old mice. Mature virus particles, dense clumps of fine granules, spherules and advanced stages of viral development i.e. cytopathic vacuoles, Type II (CPV II) are seen in the brains at all ages with the virulent strain which is pathogenic to all age group of mice. In the avirulent strain infection which is pathogenic to mice below 15 days old, no mature virus particles or advanced stages of viral development are seen in 19 day old and adult mice in spite of high virus titres. However, dense clumps of fine granules and spherules are seen which seem to have the capacity to develop into lethal highly infectious mature virus when reinoculated into 2-7 day old mice. It is suggested that the dense clumps of fine granules and spherules are very early viral forms, which are seen in all age groups of mice. The cut-off mechanism in pathogenicity of the avirulent strain occurs in mice around 14 days old. Though some mature virus particles and advanced viral developmental stages are seen in these mice they were much less frequent compared to baby mice. Lymphoblastic type cells are numerous in this age group. These cells are seen more frequently in all ages of mice infected with the avirulent strain as compared to the virulent strain. These mononuclear cells can have an immunological role and may play a part in limiting the process of viral maturation and hence preventing death. Polymorphs and macrophages are rare with the avirulent infection but are the predominant infiltrating cells in the virulent strain infections. With the avirulent infections the astrocytes show hypertrophy and intranuclear inclusions are seen in them.

Age Factors↗
PubMed1978

Virus-associated demyelination. A model using avirulent Semliki Forest virus infection of mice.

Lesions produced by the infection of Swiss/A2G mice with a single inoculation of an avirulent strain of Semliki forest virus have been studied by light and electron microscopy. Whilst a mild encephalitis was detected in the great majority of mice infected, focal areas of myelin loss were observed in the cerebellar white matter of only 25% of cases. The incidence of myelin loss in other strains of mice ranged from 21% in BSVS mice to 8% in SJL/J mice. The possible mechanisms involved in the pathogenesis of the myelin loss are discussed.

Animals↗
PubMed1978

Cytogenetic toxicity of gentian violet and crystal violet on mammalian cells in vitro.

The cytogenetic toxicity of gentian violet in Chinese hamster CHO cells in vitro has been studied by analyzing (1) squash preparations from direct fixation for recording mitotic anomalies and (2) air-dried preparations (with colcemid--hypotonic pretreatments) for recording metaphase chromosome aberrations. It was concluded that this compound is a mitotic poison as well as a clastogen in vitro. Its clastogenic property was confirmed in 5 other different mammalian cel types. 10 samples of different gentian violet and crystal violet were surveyed and all were shown to be clastogenic. Unless in vivo studies prove otherwise, gentian violet and crystal violet should be regarded as biohazardous substances.

Animals↗
PubMed1978

Induced Robertsonian fusions and tandem translocations in mammalian cell cultures.

Cultures of a cattle cell line and a Peromyscus eremicus cell line recovering from a pulse-treatment with mitomycin C, actinomycin D, 33258 Hoechst, and nitrosoguanidine exhibited translocations between chromosomes at the centromeric regions (Robertsonian fusions) as well as between centromere and telomere and between telomeres (tandem translocations). The frequency of Robertsonian fusions was found to be dose-dependent and duration-dependent with the mitomycin treatment. Biarmed chromosomes resulting from fusions may be monocentric or dicentric. Analyses of clones isolated from treated cells suggested that fused chromosomes may perpetuate in the cell populations.

Animals↗
PubMed1977

Distribution of constitutive heterochromatin in carnivores.

The distribution of constitutive heterochromatin (C-banding) in the genomes of nine species of Felidae, one species of Mustelidae, two species of Procyonidae, one species of Viverridae, one species of Canidae, and one species of Ursidae has been studied. In the chromosomes of several felid species the C-band is apparently absent. A few chromosomes show only telomeric staining in one arm or sometimes in both arms. Centromeric and interstitial distribution of heterochromatin has also been demonstrated in other species of Carnivors, but, in general, the C-banded material in felids is comparatively less in amount, and more weakly staining, than in other mammals. Induction of C-banding patterns in certain carnivore species is rather difficult, probably because of the minimal amount of heterochromatin present.

Animals↗
PubMed1977

Renal tubular abnormalities in a patient with the phenotypic appearance of C-trisomy mosaicism.

In 1971, SINHA et al. described a patient with isochromosomes arising from a C-group autosome. This patient had the phenotypic appearance of C-trisomy mosaicism. Six years later she presented with complaints of polydipsia and polyuria and was documented to have nephrogenic diabetes insipidus and renal tubular acidosis. The abnormal cell line of the patient had disappeared at the time of this observation.

Acidosis, Renal Tubular↗
PubMed1976

Chromosomes and DNA of Mus. The behavior of constitutive heterochromatin in spermatogenesis of M. dunni.

Using C-banded preparations of Mus dunni it is possible to study the behavior of constitutive heterochromatin in early stages of meiotic prophase. The X and the Y chromosomes, both of which contain a large amount of heterochromatin, lie apart in leptotene but move toward each other during zygotene. They then form the sex vesicle at late zygotene. In autosomes zygotene pairing appears to start from the telomeric ends. The centromere of the Y chromosome associates end-to-end with the terminal end of the long arm of the X chromosome. The autosomal heterochromatic short arms show forked morphology in certain bivalents at pachytene, suggesting probable incomplete synapsis.

Animals↗
PubMed1976

Fusion of two apparently intact human X chromosomes.

Cytological studies have been presented from a 15-year-old girl with short stature and failure of puberty. Buccal mucosa preparations revealed X-chromatin mass approximately double in size of that of a normal female. Leukocyte metaphases suggested a two cell line composition of the patient. One population of cells conformed with 45,X chromosome distribution. The chromosome complement of her other cell line had a modal number of 46. In this cell line a "C" chromosome was replaced by an exceptionally large submetacentric chromosome. This abnormal element exhibited late DNA replicating pattern. G-banding study revealed that the abnormal chromosome was produced as a result of fusion involving telomeric ends of long arms of 2 intact X chromosomes. This translocation X was bearing 2 C-banded areas; one around the centromere and the other at the distal end of the long arm. The distal C-band area did not show any evidence for centromeric function. It appears that a centromere becomes latent in the presence of another centromere in a translocation bearing 2 total chromosomes. Such a change of state in the additional centromere is vital for the stability of the translocation chromosome.

Adolescent↗
PubMed1976

An electron-microscopic study of the development of virulent and avirulent strains of Semliki forest virus in mouse brain.

Two strains of Semliki Forest Virus (SFV), the avirulent and virulent, were used to study the development of virus in both baby and adult mouse brain. The development of SFV in the brain was similar in baby and adult brain using the virulent strain and in the baby mouse brain using the avirulent strain. Mature virus could not be found in adult mouse brain using the avirulent strain. This paper shows that extracellular virus particles near the cell membrane stimulate the formation of coated vesicles and thus absorption of virus particles by the cell. It is suggested that these coated vesicles with contained virus particles are stimulated to develop nucleoid cores on their membrane forming cytopathic vacuoles, Type II (CPV-II). Excessive membrane growth takes place and the membrane of the CPV-II with the nucleoid cores invaginates to form intravacuolar tubules. It is suggested that these tubules become responsible fro the formation of mature virus particles. Thus the membrane of the CPV-II appears to be responsible for the development of both the inner core and outer coat of the virus.

Animals↗
PubMed1976

Giemsa-banding and the identification of the Y/autosome translocation in the african marsh mongoose, Atilax paludinosus (Carnivora, Viverridae).

The diploid chromosome number of 35 in the male and 36 in the female African marsh mongoose, Atilax paludinosus, has been confirmed. C- and G-banding analyses have shown that the Y chromosome is probably translocated onto the proximal end of the acrocentric partner of a heteromorphic autosomal pair (C3). The other partner is a subtelocentric with a heterochromatic short arm. During the translocation process, this short arm was removed and presumably lost. The sex determining mechanism in Atilax could be written as XX in the female and XYA-A in the male.

Animals↗
PubMed1976

Pachytene mapping of the male Chinese hamster.

Minced seminiferous tubules of male Chinese hamsters when treated with a mixture of trypsin (one part) and McCoy's 5a growth medium with 20% fetal calf serum (nine parts) at 4 degrees C, washed twice with the regular growth medium, incubated at 37 degrees C in growth medium for 4 h, and harvested without Colcemid and hypotonic pretreatments, gave excellent pachytene morphology for studies on chromomere patterns. The Giemsa banding patterns of all somatic metaphase chromosomes except the sex chromosomes of the hamster cells correspond well to the chromomere patterns of meiotic pachytene bivalents.

Animals↗