Search PubMed⌕ Search

Biomedical subjects

T C Hsu

Publications and source records attributed to T C Hsu.

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

Aneuploidy induction by mitotic arrestants. Effects of diazepam on diploid Chinese hamster cells.

We used diazepam, a mild mitotic arrestant, as a model chemical to develop a cytogenetic assay protocol for aneuploid induction in a diploid Chinese hamster cell system. At 100 micrograms/ml, diazepam almost completely arrested mitosis at metaphase. However, mitotic block could be quickly reversed when diazepam was removed from the medium. When the duration of arrest was relatively short (2 h), anaphases in the recovering cell population were essentially normal; but when the arresting period was prolonged (7 h), anaphases in the recovering cell populations exhibited a high rate of multipolar spindles and lagging chromosomes. Filial cell populations (18-24 h after removal of the drug) showed a high frequency of aneuploid elements. Mitotic cells shaken off from monolayer cultures as starting cell populations for enumeration of aneuploidy proved to be superior to non-shaken-off cell populations.

Anaphase↗
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

Restitution of chromatid and isochromatid breaks induced in the G2 phase by actinomycin D.

Although actinomycin D (AMD) appears to cause chromatid breakage, it has been suggested that it merely weakens the chromosomal proteins, causing breaks to occur during the stress of fixation. To determine if this was true, we examined lymphocytes treated with AMD (3.5 micrograms/ml) for 90 min prior to harvesting for evidence of DNA repair. Besides single chromatid breaks, we observed a high frequency of chromatid exchange figures (translocations, inversions, rings) and closed isochromatid breaks, indicating that a type of DNA repair leading to chromosome aberration had occurred prior to cell fixation. Therefore, at least some of the breaks observed after AMD treatment in G2 represented true DNA damage and were not merely artifacts of fixation.

Chromatids↗
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

Baseline and mitomycin-C-induced sister chromatic exchanges ina melanoma and a colon tumor cell line.

Baseline and mitomycin C (MMC)-induced sister chromatid exchanges (SCEs) in two human tumor cell lines (a colon tumor and a melanoma) and in a normal fibroblast cell line were analyzed and compared. The tumor cells showed numerical and structural chromosomal abnormalities. Their baseline SCE rate was slightly, but not significantly, higher than that of the control. Each tumor cell line showed a dose-dependent increase in SCE frequency above the spontaneous level in its own specific manner. The response in the malanoma cell was consistently below that of the control, but only the response to the highest dose of MMC (10(-9) M) was significantly lower than that of the control. The response of the colon tumor cells varied with respect to that of the control. Thus, it appears that karyotypic instability in tumor cells is not necessarily associated with elevated baseline or induced SCE/chromosome rates. In addition, within each cell line dose group, the SCE frequency was proportional to the number of chromosomes. thus, the SCE/chromosome is a better expression of genetic damage than SCE/metaphase in analyses involving heteroploid cells.

Antibiotics, Antineoplastic↗
PubMed1982

Enzymatic characterization of Aeromonas hydrophila complex by the API ZYM system.

Enzymatic characterization of 48 Aeromonas hydrophila complex isolates from various sources was determined with the API ZYM system (Analytab Products, Plainview, N.Y.). All isolates lacked valine and cystine aminopeptidases, chymotrypsin, alpha-mannosidase, alpha-fucosidase, alpha-galactosidase, and beta-glucuronidase but possessed caprylate esterase-lipase, leucine aminopeptidase, acid phosphatase, phosphoamidase, and N-acetyl-beta-glucosidase. Variability was found in the presence of alkaline phosphatase, butyrate esterase, myristate lipase, trypsin, beta-galactosidase, alpha-glucosidase, and beta-glucosidase. No significant differences were evident among the enzymatic profiles of isolates from various sources.

Aeromonas↗
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

Observations on the argentophilic properties of mammalian spermatids.

We have used aqueous silver nitrate to stain preparations of formalin-fixed meiotic cells. In doing so we have "rediscovered" a number of spermatid organelles, such as nuclear rings, acrosomal cap rings, centriolar adjuncts, and developing annuli, apparently not seen in numerous other recent studies of silver-stained meiotic cells. The availability of these structures for light microscopy coupled with the ease of preparation of the samples should facilitate studies on spermatid development, cytochemistry, and differentiation.

Acrosome↗
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

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

Silver-staining patterns of mammalian epididymal spermatozoa.

Epididymal spermatozoa from 12 species of mammals were stained using silver nitrate and examined with the light microscope. Silver nitrate differentiates many of the gross morphological features of spermatozoa, including the acrosome, subacrosomal region, perforatorium, postacrosomal sheath, neck, dense outer fibers of the core of the midpiece, annulus, principal piece, and end piece. Silver-staining patterns of spermatozoa reveal both species-specific and strain-specific differences, particularly of the sperm head. The biochemical basis of silver staining may be due in part to the presence of sulfhydryl- and disulfide-rich proteins; however, it cannot be explained entirely by the presence of these moieties. The detail obtained using silver nitrate staining, coupled with the ease and rapidity of the procedure, should be useful to workers in many areas of biological and medical research.

Acrosome↗
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↗