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Biomedical subjects

T C Hsu

Publications and source records attributed to T C Hsu.

At least 181 records · Page 10Linked to original sources
PubMed1980

Short-term cytogenetic assays of nine cancer chemotherapeutic drugs with metabolic activation.

Nine anticancer drugs were analyzed in cell cultures with respect to their cytogenetic effects with or without the addition of liver fraction S9 as an in vitro metabolic system. Among them, vincristine was the only drug which induced a significant accumulation of mitosis with or without S9. Adriamycin and neocarzinostatin were most potent in induction of chromosome breakage, but their clastogenic activities were reduced after metabolic conversion. On the other hand, cyclophosphamide had a dose-dependent activation of clastogenic effect by S9. The activity of bleomycin was enhanced by S9. S9 had no effect on the activities of actinomycin D, cytosine arabinoside, mitomycin C, and methotrexate. Vincristine showed no clastogenic property in our short-term assay system with or without S9. The activities of these anticancer drugs observed from our assay were compatible with those from other assay systems. The incorporation of S9 or other metabolic systems in routine clastogen assays should allow us to improve our understanding of the genetic toxicity of chemical agents.

Animals↗
PubMed1980

Behavior of the chromosome core in mitosis and meiosis.

A simple method has been described for the visualization of chromosomes cores with light microscopy in conventional chromosome preparations. The technique is relatively simple, highly reproducible and can be used effectively on fresh and aged slides. The following observations have been made: (1) a core existed in mitotic chromosomes in all the materials employed, confirming the findings of Howell and Hus (1979). (2) The microchromosomes of the chicken and double minutes of a human carcinoma cell line also exhibited the core structure. (3) The core structure of meiotic chromosomes appear weak, disorganized, and disintegrating.

Animals↗
PubMed1980

The genotoxic effects of adriamycin in somatic and germinal cells of the mouse.

The genotoxic effects of adriamycin on somatic and germinal cells were studied in mice treated with single injections of 3, 12 or 24 mg/kg of the drug. From 1 to 5 days post-injection, chromosome aberrations were observed in bone-marrow cells and in diakineses-metaphase I cells from the testes. The frequency of chromosome breakages peaked at 5 h or 1 day for the bone marrow and at 3 and 5 days for the testis. Univalent formation was increased overall but did not have a dose- and time-dependent relationship. In long-term follow-up studies, adriamycin was found to induce cell killing of germline cells which resulted in a reduction in the numbers of spermatocytes and sperm from mice treated with the higher doses. There was complete absence of gametogenetic elements and, eventually, testicular atrophy occurred. In mice treated with 3 mg/kg, there was gradual recovery of spermatogenesis from 50 days onward. Chromosome breaks and translocations were again observed in the recovering spermatocytes. It was concluded that some of the chromosome aberrations must have been induced in the spermatogonial cells which had survived.

Animals↗
PubMed1980

Mosaicism of red cell ABO type without recognizable cause.

A 19-year old woman has been found whose red cells are a mixture of groups A1B (60%) and A1 (40%). Tests for many other genetic markers show no other evidence of mosaicism. She is not a twin and her parents and a sib are of normal ABO type. The cause of her dual population of red cells cannot be established, but may be an effect of somatic crossing over or mutation.

ABO Blood-Group System↗
PubMed1979

S1 nuclease definition of highly repeated DNA sequences in the Guinea pig, Cavia porcellus.

Native DNA of the Guinea pig, Cavia porcellus, purified from liver or tissue culture cells, was heat denatured and reassociated to a Cot value of 0.01 (equivalent Cot value of 7.2 x 10(-2)). The reassociated DNA was isolated by digestion with the single-strand DNA specific enzyme S1 nuclease. Spectrophotometric and radioactivity assays demonstrated that 24% of the total DNA was resistant to S1 nuclease treatment. Zero-time reassociation indicated that approximately 3% of the DNA was inverted repeat sequences. Thus, highly repeated sequences comprised 21% of the total genome. CsCl buoyant density ultracentrifugation indicated that this fraction was composed of both main band and satellite sequences. Although actinomycin D - CsCl density gradients failed to give significant separation of the repetitive sequences, distamycin A - CsCl gradients were able to fractionate the DNA into several overlapping bands. The heterogeneity of the repetitive DNA was further demonstrated by the first derivative plots calculated from their thermal denaturation profiles. This analysis revealed six major thermalytes which indicate that there may be at least six discrete components in the repetitive DNA.

Animals↗
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

Chromosome core structure revealed by silver staining.

Chromosomes were subjected to either prolonged hypotonic solution pretreatment or aging. Both conditions greatly loosened and dispersed the overlying epichromatin from the central chromosome core structure. This was followed by silver staining and examination with bright-field microscopy. The chromosome core selectively reduced the silver and stained black while the surrounding epichromatin stained yellow. A single core was seen extending the length of each chromatid. Nucleolus organizer regions appeared to be attached to the core, while kinetochores seemed to be specialized regions of the core itself. Cytochemical tests indicated that the core component(s) responsible for silver staining was non-histone protein(s).

Adenocarcinoma↗
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

Studies on the clastogenic effects of biologic stains and dyes.

We have surveyed the clastogenic potential of 12 different groups of stains and dyes totalling 48 compounds. We observed that 18 compounds induced significant increase in chromosome damage. Most of them were also found to be mutagenic, carcinogenic, or toxic in other reported studies. However, no significant studies were reported on six of them. It is concluded that these agents are potentially harzardous and should be studied further in detail.

Animals↗
PubMed1979

Identification of a silver binding protein associated with the cytological silver staining of actively transcribing nucleolar regions.

Nucleoli isolated from Novikoff hepatoma cells were stained with AgNO3 to demonstrate the typical staining of active ribosomal cistrons. Pre-treatment of the nucleoli with 80 mM Tris-HCl (pH 7.5) -- 2.0 M NaCl did not interfere with silver staining. Treatment of the nucleoli with 80 mM Tris-HCl (pH 7.5) -- 0.15 M NaCl did, however, eliminate silver binding. Serial extraction of nucleoli with 2.0 M NaCl buffer followed by 0.15 M NaCl buffer also abolished silver staining. Analysis of the supernatant fraction of these extracts by polyacrylamide gel electrophoresis indicates that, although more than one nucleolar protein can bind silver, only one protein is associated with the staining of active ribosomal cistrons.

Animals↗
PubMed1979

The low ionic strength reaction of human blood: relationship between the binding of serum immunoglobulin and complement of red blood cells and surface charge of the cells.

Using the sucrose haemolysis reaction of Hartmann & Jenkins (1966) as a basic model, the low ionic strength reaction (LISR) of human blood was studied to determine: (1) serum Ig uptake by RBC with saline elution and 125I-IgG uptake, and (2) complement fixation (CF) to RBC with lysis of PNH cells and C3H/C4 antiglobulin haemagglutination (AH) of normal cells. The saline eluates were found to contain IgG and IgM with traces of IgA; their pH optima for the uptake by RBC were 6.0 +/- 0.5, 5.5 +/- 0.5 and c 5.0 respectively. The ratio of bound IgG to IgM was linearly related to the uptake pH. Both C4 AH and lysis were found to be optimum at pH 6.0--7.5, whereas the maximum C3 AH was at pH 6.0 +/- 0.5. The LISR performed at a constant pH (6.1 +/- 0.1) showed that an increasing concentration of neuraminidase (VCN) used in pretreatment of RBC was associated with a decrease in both IgG uptake and CF activity. A maximum VCN effect reduced the Ig uptake to c 20% of normal and abolished almost all the CF activity. An impaired LISR to various degrees was also observed with RBC pretreated with ficin, papain, bromelin, trypsin or protamine, and RBC from two individuals of En(a-) type. Preincubation of serum at LIS with and without RBC resulted in respectively a 'complete' and partial consumption of C in the fluid phase. The latter was not enhanced or inhibited by the addition of VCN-treated RBC for preincubation. A hypothesis is proposed suggesting that in the LSR the Ig uptake by RBC is an electrostatic interaction of the oppositely charged RBC and Ig and the CF to RBC results from C activation by the cell-bound IgG and IgM. In addition, a pH-dependent inactivation of the cell-bound C3 in the LISR is demonstrated.

Complement Fixation Tests↗
PubMed1979

C3d antiglobulin haemagglutination of human red blood cells. A demonstration of two types of cell-bound C3d by means of typsin digestion.

Washed human red blood cells from blood collected in EDTA were tested by Auto-Analyzer for a percentage of maximum antiglobulin haemagglutination (AH) using monospecific antisera to human C3d and C3c. The cells from normal persons were found to be agglutinated by anti-C3d but not by anti-C3c. To a fixed dilution of antiserum, the normal C3d AH values (X +/- 2 SD) were 34 +/- 19% for adult cells (n = 29) and 14 +/- 19% for cord cells (n = 19); the difference was significant (P less than 0.0001). By pretreatment of these cells with trypsin the C3d AH was either completely abolished or markedly reduced. Its difference between the adult and cord cells was eliminated as the observed values were 4 +/- 7% and 3 +/- 4% respectively (P = 0.15). The supernatant fluid of cell-trypsin mixture, treated with trypsin inhibitors, was found to be inhibitory to C3d AH but not to C3c AH. In contrast, the AH of C3d-coated red blood cells resulting from complement fixation in vivo (ie, cold agglutinin disease) or in vitro (eg, sucrose water reaction) was resistant to trypsin treatment. The difference between the trypsin-sensitive and trypsin-resistant cell-bound C3d is postulated to be at its attachment mechanism to the cell membranes. In addition, both the advantage and limitation of using trypsinised cells for C3d antiglobulin tests are demonstrated.

Adult↗
PubMed1979

Induction of high frequencies of endoreduplication in mammalian cell cultures with 33258 Hoechst and rubidazone.

Cells of the mouse L strain and the Chinese hamster CHO line were treated with 33258 Hoechst, rubidazone, and a combination of these. Recovering cell populations following the drug removal exhibited a high frequency (20--50%) of metaphases with diplochromosomes (endoreduplication), especially in the combination treatment series (up to more than 70% in the L strain). Such a procedure should be useful in probing the mechanisms of the endoreduplication process.

Animals↗
PubMed1979

Double minutes in human carcinoma cell lines, with special reference to breast tumors.

Small DNA-containing particles called double minutes (dm) were observed in metaphases during a survey of human tumor cell lines. Detection of dm in uncultured malignant effusions, in a series of 14 breast carcinoma cell lines, and in a cervical carcinoma cell line, and a literature survey indicated that dm may be more common among human malignant cells than previously suspected. Some of the human breast carcinoma cell lines showed a high incidence of dm, which permitted a series of cytochemical studies. The dm stained identically with euchromatic regions of human chromosomes. Unlike typical chromsomes, dm contained neither C-bands nor Cd bands indicative of paracentromeric heterochromatin and centromeres, respectively. The dm were observed to cluster at the ends of chromosomes, and individual dm adhered to chromosomes. This clustering behavior allows dm to pass through cell division in the absence of centromeric regions. These results should alert tumor cytogeneticists to the possibility that their material may contain a low incidence of undetected dm.

Adenocarcinoma↗
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↗