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Biomedical subjects

S Pathak

Publications and source records attributed to S Pathak.

At least 163 records · Page 9Linked to original sources
PubMed1983

Involvement of chromosome 6 in rearrangements in human malignant melanoma cell lines.

We analyzed the karyotypes of nine established human malignant melanoma cell lines derived from two female and six male patients. Each of the cell lines had an aneuploid stemline chromosome number. Analysis of G-banded chromosomes identified a number of altered (marker) chromosomes in these cell lines; in all the lines, chromosome 6 was found to be involved in the marker chromosomes. A review of the literature and these cases showed that of 47 cell lines or primary melanoma cells karyotyped, 38 (80.8%) had a marker involving the 6. We believe that the genetic factor determining melanoma initiation is located in the distal segment of 6q. Deletion of this segment or the entire 6q is responsible for the cell's (melanoblast or melanocyte) becoming malignant. The proximal segment of 6q and 6p can be involved in marker formation.

Cell Line↗
PubMed1982

Familial renal cell carcinoma with a 3;11 chromosome translocation limited to tumor cells.

Cytogenic studies were performed on the direct chromosome preparations of the renal cell carcinoma cells and the cultured peripheral blood lymphocytes of a patient with familial renal cell carcinoma. The results revealed a specific, acquired translocations (3p;11p) present in the majority of metaphases of the tumor, indicating that the development of renal cell carcinoma is associated with a deletion in the proximal end of 3p. Renal cell carcinoma is thus the third example--the first two being retinoblastoma and Wilms' tumor--of a chromosomal deletion occurring germinally or somatically in association with a specific tumor. This finding adds further support to the existence of specific human cancer genes.

Adenocarcinoma↗
PubMed1982

Dense bodies in silver-stained spermatocytes of the Chinese hamster: behavior and cytochemical nature.

From the silver staining behavior of various organelles in the nucleus we have divided meiotic prophase (leptotene to the diffuse stage) of the male Chinese hamster into five stages. Components within the nucleus, such as synaptonemal complex (SC), sex bivalent (SB), nucleolus organizer regions (NORs), chromatin and the dense bodies, showed a characteristic feature in each stage of meiotic prophase. The lampbrush chromosome stage was found to be followed by the diffuse stage. The chromatin around SC began to be organized at early pachytene and formed a brush-like structure at late pachytene. During early prophase stages a dramatic change in SB morphology occurred. Three types of morphology of SB were recognized: (1) the XY pair with long synapsis and fusiform or diffuse thickening of the unpaired portions (late zygotene and early pachytene), (2) desynapsed, branched, and anastomosed axes seen at late pachytene. Two types of the dense body were found during meiotic prophase; the double body in early stage (leptotene to early pachytene) and the single body in later stages (mid pachytene to diffuse stage). The small precursors of the double body existed at early leptotene but they increased in size and also changed the silver stainability during zygotene, becoming the characteristic double body consisted of one light body (L-body) and one dark body (D-body). These two bodies can also be recognized after Giemsa or acridine orange (AO) staining. The L-body fluoresced reddish orange after AO staining. The single body, which is probably formed by amalgamation of the D- and the L-bodies, showed a staining reaction similar to that of the D-body. Data from pancreatic lipase and protease treatments suggest that the D-body contained a lipoprotein.

Animals↗
PubMed1982

Cytogenetic abnormalities in a patient with hypercalcemia and papillary thyroid carcinoma.

Cytogenetic examinations on multiple peripheral blood cultures of a patient with papillary thyroid carcinoma and hypercalcemia revealed with following features: (1) The average frequency of cells with aberrations was 11.6%, considerably higher than in controls. Among metaphases with chromosomal abnormalities, 4.5% has chromosome-type aberrations. (2) One homolog of chromosome 11 showed a fragile site in the proximal end of the long arm, and in three metaphases the segment distal to the fragile site showed "branched morphology." (3) The rate of sister chromatid exchanges was within normal limits (8.78/metaphase). (4) The patient's two sons showed 7.0% and 5.0% abnormal metaphases, in the high normal range.

Carcinoma, Papillary↗
PubMed1982

Demonstration of kinetochores and centrioles in spermatocytes of two species of cockroaches by silver staining.

Light microscopy following silver staining of spermatocytes of German and Madagascar hissing cockroaches demonstrated: (1) the localization of a kinetochore in each autosomal synaptonemal complex during pachytene, and (2) visualization of centrioles in different stages of meiotic prophase. The presence of a "hairpin-like" twist and the nucleolus organizer region in the X-chromosome was observed only in the German cockroach.

Animals↗
PubMed1982

Characterization of a cell line (SW756) derived from a human squamous carcinoma of the uterine cervix.

An established cell line, SW756, derived from a primary squamous carcinoma of the uterine cervix is described by its morphology, ultrastructure, karyotype, genetic signature analysis, HLA typing, and tumorigenesis in the nude mouse. Cultured cells obtained from the SW756 derived nude mouse tumor also were studied for chromosome and isozyme markers. The original tumor was poorly differentiated carcinoma with minimal keratinization and is compared with that occurring in the nude mouse after the cultured cells were inoculated. The nude mouse tumor showed similar histological features, but better differentiation than the original tumor. Karyotype analysis of SW756 demonstrated a hyperdiploid stem line number and several marker chromosomes (MI-M6). No HeLa marker chromosomes were identified. The isozyme pattern for SW756 reported by others has been confirmed. The unique chromosome and isozyme features have been identified repeatedly in the cultured cells and, most importantly, in the post nude mouse culture. We recommend SW756 as a defined human tumorigenic cell line derived from a primary squamous carcinoma of the uterine cervix.

Animals↗
PubMed1982

High resolution G-banding patterns of Syrian hamster chromosomes.

The late prophase, prometaphase, early metaphase, and metaphase chromosomes of Syrian hamster embryo fibroblast cells were G-banded using a technique combining actinomycin D pretreatment and Wright/Giemsa staining. Late prophase chromosomes have approximately twice as many bands as metaphase chromosomes, whereas prometaphase and early metaphase chromosomes have intermediate numbers of bands. An idiogram for metaphase and late prophase chromosomes is presented, and a nomenclatural system for identifying individual bands of Syrian hamster chromosomes is proposed.

Animals↗
PubMed1982

Heterochromatin, synaptonemal complex, and NOR activity in the somatic and germ cells of a male domestic dog, Canis familiaris (Mammalia, Canidae).

C-banding and silver staining of the somatic and germ cells of the male domestic dog. Canis familiaris, have shown that: (1) the amount of C-banding is small compared to most other mammalian species, (2) three pairs of autosomes have nucleolus organizer regions (NORs) at the terminal ends of their long arms, whereas the Y chromosome has an NOR on the terminal end of the short arm, (3) the organization of the synaptonemal complex (SC) is similar to that of other mammalian species, (4) a distinct SC is formed between the long arm of the Y chromosome and probably the short arm of the X chromosome, and (5) the differential axes of both sex chromosomes do not demonstrate fusiform thickenings nor do they stain darkly with silver as do the XY bivalents in many other mammalian species.

Animals↗
PubMed1981

NOR lateral asymmetry and its effect on satellite association in BrdU-labeled human lymphocyte cultures.

Second generation BrdU-labeled acrocentric chromosomes exhibit NOR lateral asymmetry (NLA) in metaphases that have been sequentially stained with silver and the Hoechst-Giemsa sister chromatid differential (SCD) technique. The NLA presumably results from suppression of NOR activity in the doubly-substituted chromatid. Examination of single chromatid (NOR) associations in pairs of acrocentrics reveals that light chromatids associate less frequently than dark chromatids and that the frequency distribution of dark and light alignment configurations can be explained by this differential tendency to associate. Thus, it appears that a hypothesis of non-random chromatid segregation as an explanation for non-random chromatid alignments in associating acrocentric chromosomes is unwarranted.

Adult↗
PubMed1981

Synaptonemal complex of the sex-autosome trivalent in a male indian muntjac.

Bright-field microscopy of silver-stained pachytene spermatocytes of a male Indian muntjac, Muntiacus muntjak revealed that (a) the synapsis between the autosomal homologs, including the long arm of the X and Y2, was normal, (b) the nucleolus organizer regions were present in both the No. 1 bivalent and the long arm of the X and Y2, (c) the accessory structures of the X chromosome short arm in the forms of light and dark thickenings and the hairpin-like bend were present despite the X-autosome translocation, (d) a short synaptonemal complex was present between the Y1 (real Y) and the short arm of the X chromosome, and (e) the centromeric orientation of the Y1 and Y2 chromosomes was in Cis configuration as opposed to the X chromosome.

Animals↗
PubMed1981

Cytogenetic analysis on eight human breast tumor cell lines: high frequencies of 1q, 11q and HeLa-like marker chromosomes.

The chromosomal constitution of 8 human breast tumor cell lines has been analyzed by conventional staining and G-banding methods. The stem line number was established in each case. In all cell lines, a large number of marker chromosomes have been identified. In addition to the 1q marker chromosome, previously reported to be present in several breast tumors from this laboratory, we also found marker chromosomes involving the 11q segment in all 8 cases, and markers resembling some of those found in the Hela cells in 6 out of 8 lines. It appears that the primary genetic (and cytogenetic) changes are specific for each type of target cell and are not shared by other neoplasms. Marker chromosomes found in different types of tumors may represent genetic changes associated with cancer progression, which may be the result of a multitude of genetic alterations.

Breast Neoplasms↗
PubMed1981

Gametogenesis in a male Indian muntjac x Chinese muntjac hybrid.

Histological and cytogenetic examinations of testicular preparations from a male hybrid between an Indian muntjac x Chinese muntjac showed a certain degree of chromosomal homology, as evidenced by the synaptic behavior. The male hybrid is considered sterile because spermatogenetic stages were arrested at early prophase. Silver staining demonstrated that the nucleolus organizer regions of both parents were expressed, but no synaptonemal complex and sex vesicle were observed.

Animals↗
PubMed1981

Chromatid lesions and chromatid core morphology.

A silver-staining technique revealed the core morphology of metaphase chromosomes of irradiated CHO cells with chromatid lesions (breaks, gaps). These cells were photographed before and after silver staining. As a rule, the core was not continuous in chromatid gaps, suggesting that the chromatid is broken in many so-called gaps. Ten cytogeneticists who were asked to classify chromatid gaps and breaks from photographs of chromosome lesions before silver core staining agreed in only 19 of 53 cases.

Animals↗
PubMed1980

Silver-stained accessory structures on human sex chromosomes.

Using a combination of silver-staining and light microscopic techniques on human male meiotic preparations, it is feasible to study the morphology and behavior of both autosomal synaptonemal complexes and sex chromosome axes. During leptotene and early zygotene, the X and Y chromosomes are separate; their axes appearing as thin, filamentous structures. During late zygotene/early pachytene, the sex chromosomes come close to each other and a distinct sex vesicle is formed. We confirm existence of a short synaptonemal complex between the terminal ends of the X and Y chromosomes. In our preparations, a number of accessory structures can be seen along the axes of the sex chromosomes. These structures appear to be similar in morphology to those previously observed in several other mammalian species.

Aged↗