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C Nowak

Publications and source records attributed to C Nowak.

At least 19 recordsLinked to original sources
PubMed1990

Induction of sister chromatid exchanges with hypotonic treatment.

Hypotonic NaCl solutions and diluted culture medium were tested for induction of sister chromatid exchanges (SCEs) and chromosomal aberrations (CA). Hypotonic treatment conditions were found to induce high frequencies of CA and SCEs. However, an increase in SCEs was observed only in cells that also had CA. Possible lesions and mechanisms leading to SCEs and CA are discussed.

Animals↗
PubMed1990

Chromosomal aberrations in V79 hamster cells induced by hyperosmotic solutions of NaCl.

In this study V79 hamster cells were treated with hypertonic NaCl solutions. A pulse treatment of 30 min made it possible to use hypertonic solutions of up to 1500 mM. Hypertonic treatment induced high frequencies of chromosomal aberrations and the aberration pattern led to the conclusion that hypertonicity acts similarly to S-phase-independent mutagens. We also tested the influence of several parameters on aberration induction and tried to standardize the experimental protocol. The mechanisms involved in aberration production after hypertonic treatment are unknown, we discuss a change in chromatin structure, inhibition of repair processes or protein damage responsible for chromosomal aberrations.

Animals↗
PubMed1990

The use of multiple sampling times in in vitro chromosome assays.

Asynchronously growing V79 hamster cells were treated with hypotonic solutions of different osmolalities, with ethyl methanesulfonate (EMS) or a combination of these 2 agents. Four different fixation times (8, 10, 14, 18 h) were tested. Hypotonic treatment alone induced chromosomal aberrations (CA), leading to very high frequencies at low osmolalities (50 mOsm/kg H2O). EMS also induced CA, but a comparison of EMS and hypotonicity revealed that EMS induced fewer aberrations at the maximum doses tested. A combined treatment produced contradictory results, depending on the sampling time: 8 and 14 h led to a clear elevation of EMS-induced CA by hypotonicity, 10- and 18-h sampling times led to a decrease in the aberration frequency in EMS and hypotonically treated cells. The observation that the choice of sampling time significantly influences the incidence of chromosomal aberrations is of particular interest for in vitro assays. In this study the 4 different sampling times are not enough to allow meaningful conclusions about additive or synergistic effects of the mutagens tested. These contradictory results are caused, on the one hand, by the very steep dose-response curve after hypotonic treatment and on the other hand by the varying degree of cell-cycle delay after combination treatment. This makes a valid comparison of the CA frequencies impossible because no 2 sampling times contain the same mixture of cells.

Animals↗
PubMed1990

Hypotonic treatment leads to chromosomal aberrations but not to sister-chromatid exchanges in human lymphocytes.

Human peripheral lymphocytes were isolated from whole blood and exposed to culture medium of reduced osmolality. This hypotonic treatment led to a significant increase in the frequencies of chromosomal aberrations when the osmolality was reduced to 60 mOsm/kg H2O and below. Maximum damage occurred when the hypotonic treatment was done 27 or 30 h after starting the cultures. We also looked for the induction of sister-chromatid exchanges (SCE) by hypotonic culture conditions, but the SCE frequencies were not influenced.

Cell Cycle↗
PubMed1979

[Studies on biological characterization of mammary tumours of the Sprague-Dawley-rat in the syngeneic tumour-host system. III. Metastatic experiments with primary tumours, transplantation passages and metastatic cells (author's transl)].

The metastatic spread following intravenous application of cells from primary and transplanted mammary carcinomas is described. When using cells from primary tumours the incidence rate was between 0 and 17%, but was much higher in the case of advanced tumours (transplantation passages and metastases).

Animals↗
PubMed1979

[Antineoplastic activity of the anthracycline antibiotic violamycin BI in mice and rats using experimental metastases models (author's transl)].

The report describes the antineoplastic activity of violamycin BI on three rodent tumour systems. The test systems are two syngeneic mouse tumours: a benzo(a)pyrene induced sarcoma and a spontaneously originated mammary carcinoma of the inbred strain XVII/Berlin. Both tumours grow in ascitic form and were weekly passaged by i.p. administrations. A third system is a dimethylhydrazine induced rectum carcinoma of the Wistar rat. This rat tumour represents a slowly growing system transplanted by s.c. administrations of tumour fragments. The principle of the screening consists of the evaluation of metastatic parameters, e.g. weight, number and growth rate of metastases, experimentally induced by i.v. administrations of tumour cell suspensions. Under the given experimental conditions violamycin BI represents an antineoplastic antibiotikum with a good effectivity which is superior to the effectivity of the reference antibiotic daunorubicin.

Aminoglycosides↗
PubMed1978

[Plagiocephaly].

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Adult↗