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S Pathak

Publications and source records attributed to S Pathak.

At least 91 records · Page 5Linked 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

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

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

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

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↗
PubMed1980

Integration site(s) of herpes simplex virus type 1 thymidine kinase gene and regional assignment of the gene for aminoacylase-1 in human chromosomes.

To investigate the chromosomal sites of integration of the herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) gene in HSV-1-transformed human HeLa(BU25)/KOS 8-1 cells, the biochemically transformed cells were fused with TK-negative mouse LM(TK-) cells, and human-mouse somatic cell hybrid lines (LH81) were isolated using a HATG-ouabain selection system. The presence of HSV-1 TK activity in the hybrid lines was verified by disc polyacrylamide gel electrophoresis (PAGE) and by enzyme neutralization with type-specific rabbit anti-HSV-1 TK immunoglobulin. Karyotype analyses of several somatic cell hybrid clones using G-banding, Hoechst 33258 staining, and combined G-banding and Hoechst staining demonstrated that they retained only a few human chromosomes. A marker chromosome, M7, consisting of a chromosome 17 translocated to the short arm of 3, occurred in 25 of the 28 metaphases examined. Also chromosomes 8 and X were found in a minority of metaphases. Isozyme analyses showed that all 19 hybrid clones analyzed expressed human aminoacylase-1 (ACY1) and esterase D (ESD), markers for 3 and 13, respectively. Back-selection of somatic cell hybrid clones with 5-bromodeoxyuridine resulted in the isolation of several subclones lacking HSV-1 TK activity, human ACY1, human ESD, and the human chromosomes. These experiments suggest that the HSV-1 TK gene is associated with either M7 or a segment of 13, or both, in biochemically transformed HeLa(BU25)/KOS 8-1 cells. These experiments also permit localization of the ACY1 structural gene to the pter leads to p12 region of 3.

Amidohydrolases↗
PubMed1979

Induction of prematurely condensed chromosomes from testicular cells of the mouse.

Mitotic CHO cells and mouse testicular cells were fused with polyethylene glycol. Several types of prematurely condensed chromosomes were observed. From chromosome morphology it was possible to determine that most of the PCC represented mouse cells. Labeling of either the CHO cells in vitro or the testicular cells in vivo with 3H-TdR prior to fusion also demonstrated that the PCC were derived from the mouse cells. In some PCC, 20 chromosomes could be counted, the haploid number for mouse. It is assumed that these PCC were induced in mouse spermatid nuclei.

Animals↗
PubMed1979

Observations on the synaptonemal complex in Armenian hamster spermatocytes by light microscopy.

Using the silver staining technique, in somatic and meiotic chromosomes of the Armenian hamster (Cricetulus migratorius), it is possible to stain synaptonemal complexes (SCs) and the nucleolus organizer regions (NORs) in early spermatocytes. There are five pairs of autosomes (Nos. 2, 4, 6, 7, and 8) which have terminally located NORs. Synaptonemal complexes and accessory structures present in the sex chromosomes within the sex vesicle can be easily observed using light microscopy.

Animals↗
PubMed1979

Silver-stained structures in mammalian meiotic prophase.

Silver staining of mammalian spermatocytes revealed, in light microscopy, synaptonemal complex and structures within the sex vesicle. It is feasible to follow the chromosome pairing phenomenon from zygotene to pachytene by examining the behavior of synaptonemal complexes. Nucleolus organizer regions take heavy silver stain in pachytene but are no longer detectable in later stages of meiosis.

Animals↗
PubMed1979

Detection and analysis of a glucose 6-phosphate dehydrogenase phenotype B cell line contamination.

Eight of approximately 100 cell lines derived at the Scott and White Clinic from human solid tumors were found to have the same phenotypes when analyzed for 15 polymorphic enzymes at the Sloan-Kettering Institute for Cancer Research. These data were confirmed at the M. D. Anderson Hospital and Tumor Institute. The similarity was supported by cytogenetic studies at both institutions. The chronology of the establishment of these cell lines and isoenzyme and cytogenetic studies indicated that six of these lines have cross cell contamination. These include SW-527 and SW-613 mammary carcinomas, SW-598 meningioma, SW-608 astrocytoma, SW-732 cervix carcinoma, and SW-733 bladder carcinoma. Our data supported the authenticity of SW-480 and SW-620, which were derived from a colon carcinoma and its metastasis, respectively, from the same patient.

Animals↗
PubMed1979

Sterility in hybrid cattle. I. Distribution of constitutive heterochromatin and nucleolus organizer regions in somatic and meiotic chromosomes.

The distribution of constitutive heterochromatin and nucleolus organizer regions (NOR's) in somatic as well as in meiotic chromosomes of Bos taurus, Bos banteng, Bison bison, and their hybrids are analyzed. C-bands are present in the centromeric regions of every autosome. The X chromosome does not show a distinct C-band in the centromeric region, whereas the Y chromosome contains an appreciable amount of C-band material. In somatic metaphases, NOR's are present on the telomeric ends of five pairs of autosomes. During pachytene, five autosomal bivalents contain NOR's on their terminal ends. Meiotic preparations made from sterile bulls did not contain stages beyond the degenerating pachytene, which are C-banding, more frequently showed clustering of heterochromatin than did the pachytene stage in normal bulls.

Animals↗
PubMed1979

Cytogenetic research techniques in humans and laboratory animals that can be applied most profitably to livestock.

The usefulness of various chromosome banding techniques, i.e., Q, C, G, R, Ag-NOR, and SCE, which are currently in use in many clinical cytogenetics labortories are discussed. Since C-banding revealed the location of constitutive heterochromatin, it must be applied in conjunction with Q, G, or R-banding techniques. For the longitudinal differentiation of mammalian chromosomes one can use either the G-banding or the Q-banding and, if possible, R-banding technique. The results of such studies should not only contribute to our understanding of cytogenetics of domestic animals but also assist breeding programs and improvement of livestock.

Animals↗
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↗