Anabolic steroids--action on cellular level.

Although the nature of actions of anabolic steroids is principally that of androgens, it still remains difficult to relate the effects observed to specific cellular processes and to describe them clearly as related to specific mechanisms of action. The dissociation between "anabolic" and "androgenic" actions of a steroid can in part be explained by organ specific patterns of steroid-metabolizing enzymes, which lead to the formation of more or less active compounds in different organs. Some actions of anabolic steroids, particularly that in skeletal muscle are obviously also mediated by interaction of the parent compound or a metabolite with receptors of other steroid classes than androgens, e.

RITA--Registry of Industrial Toxicology Animal-data--progress of the working group.

A data base for the collection of histopathological diagnoses of neoplastic and pre-neoplastic lesions and related data from control animals involved in long-term carcinogenicity or toxicity studies has been operated since 1988. Factors which may have an influence on the spontaneous tumor rate are integrated in the data base. Systematized nomenclature and standardized diagnostic criteria have been established as well as the applied data acquisition and data validation procedure.

Potassium channel activation improves blood flow pattern of conscious rats in cutaneous microcirculation.

1. A dose-dependent mean arterial blood pressure reduction (tailcuff method) to an intravenously administered potassium channel activator (22 or 24 micrograms/kg bw) was found in conscious rats. 2.

Atypical malignant mesotheliomas with osseous and cartilaginous differentiation after intraperitoneal injection of various types of mineral fibres in rats.

The histopathological appearance of malignant mesotheliomas with osseous and cartilaginous differentiation is described in detail. Bone and cartilage occurred in mixed and sarcomatoid mesotheliomas which were induced by intraperitoneal injection of various types of asbestos fibres (asbestos cement, crocidolite, UICC-amosite, UICC-chrysotile B, Calidria-chrysotile). Bone or cartilage were found in 32.

Effect of photocorrosion on cadmium sulfide suspensions applied in animal inhalation studies with CdS particles.

Cadmium sulfide aerosol (90 micrograms Cd/m3) was generated from an aqueous suspension for 12 weeks and the ratio of Cd++/Cdtotal in the suspension and the resulting aerosol was determined. After 4 weeks the concentration of Cd++ in the suspension and the aerosol leveled off at 43.5 +/- 11.

Variations in prevalence of endocrine tumors among different colonies of rats? A retrospective study in the Hannover registry data base.

Illustrated by data derived from the endocrine system it could be demonstrated that at least the following requirements have to be fulfilled when using historical control data for the interpretation of animal studies: The main and basic requirement is the utilization of standardized diagnostic criteria and a systematized nomenclature for all data which should be compared. This includes the historical control data as well as histopathological diagnoses obtained from other animal studies. All findings stored in the REGISTRY are based on standardized criteria and this nomenclature was also applied for the more recent studies which were evaluated by pathologists of the member companies.

Osteochondroma in laboratory rats: a report of 3 cases in a Fischer-344, a Sprague-Dawley, and a Wistar rat.

Three cases of osteochondroma in a male Sprague-Dawley (SD) rat, a female Fischer (F344) rat, and a male Wistar rat are described. The rats were aged between 26 and 30 months. All osteochondromas were considered to be of spontaneous origin.

Pulmonary carcinogenicity of cadmium by inhalation in animals.

Although, the tumorigenic effect of cadmium after subcutaneous and intramuscular injection has been known since 1961, lung tumours after inhalation exposure were reported only more than 20 years later by Takenaka et al. (1983), using cadmium chloride aerosols. Based on these results, aerosols of cadmium sulfate, cadmium oxide and cadmium sulfide pigment were investigated for carcinogenic effects after inhalation exposure in rats, hamsters and mice.

Microclones derived from the mouse chromosome 7 D-E bands map within the proximal region of the c14CoS deletion in albino mutant mice.

A group of radiation-induced perinatal-lethal deletions that include the albino (c) locus on mouse chromosome 7 causes failure of expression of various hepatocyte-specific genes when homozygous (S. Gluecksohn-Waelsch, 1979, Cell 16:225-237). The transcription of such genes could be controlled in trans by a regulatory gene(s) located within the proximal region of the C14CoS deletion.

Alveolar retention and clearance of insoluble particles in rats simulated by a new physiology-oriented compartmental kinetics model.

A physiology-oriented compartmental kinetics model of alveolar retention of inhaled insoluble particulate matter in rat lungs was proposed in a recent paper, (W. Stöber, P.E.

A field intercomparison and fundamental characterization of various dust samplers with a reference sampler.

The European Economic Community Council Directive 80/779/EEC describes air quality limit values and guide values for sulfur dioxide and suspended particulates. However, article 10, paragraph 1 does not define well enough the reference method required, amongst others, for the gravimetric measurement of suspended particulates. It is explicity stated in article 10, paragraph 5 of the directive, that "the commission shall, in selected locations in the member states and in cooperation with the latter, carry out studies on the sampling.

Precocious induction of tyrosine aminotransferase mRNA by hydrocortisone in cultured fetal rat hepatocytes at different developmental stages.

Tyrosine-aminotransferase (TAT) is encoded by a liver-specific gene known to be expressed perinatally. Fetal rat hepatocytes (gestation day 19) in primary cultures, in which TAT gene expression is normally undetectable, are induced by hydrocortisone to express TAT-mRNA in a dose-dependent manner (greater than 10(-7) M). In hepatocytes incubated with hydrocortisone, TAT-mRNA levels were marginal after 24 hours, reaching maximal levels at 48 hours.

Investigation on the carcinogenic effects of various cadmium compounds after inhalation exposure in hamsters and mice.

The inhalation of cadmium chloride aerosols induced lung carcinomas in rats (3). Subsequently, CdCl2 was classified as probably carcinogenic in humans (2). Thus the Cd compounds CdCl2, CdSO4, CdS and CdO were investigated for their carcinogenic potencies in the lungs of hamsters and mice.

Reversibility of biochemical and cytological alterations in broncho-alveolar lavagate upon cessation of dust exposure.

The objectives of the present study were: 1. To investigate the nature and time course of the biochemical and cytological changes following acute and subchronic exposure intervals. 2.

Lung response to test toner upon 2-year inhalation exposure in rats.

SPF F-344 rats were exposed 6 h/day 5 days/wk for up to 24 months to a special test toner at 0, 1, 4 and 16 mg/m3 or TiO2 at 5 mg/m3, or SiO2 at 1 mg/m3, by the inhalation route. The animals were kept for an additional 6 weeks in filtered air. Surviving animals were sacrificed at 25.

Reversibility of clearance impairment after subchronic test toner inhalation.

In a chronic study of a test toner in F-344 rats an impairment of alveolar clearance and increased toner retention were observed at the high and, to a lesser degree, at the middle exposure level throughout the study. The objectives of the present study were: 1. To investigate the nature and the time course of test toner and surrogate tracer alveolar clearance and toner retention behaviour following a subchronic exposure interval.

Altered growth factor requirements and cell cycle control in rat hepatoma cells versus adult rat hepatocytes in culture.

Adult rat hepatocytes multiply in primary cultures when incubated in arginine-free MX-83 medium supplemented with dialyzed fetal calf serum, insulin, glucagon, hydrocortisone, epidermal growth factor, and transferrin. In the absence of mitogens, the fraction of the cells engaged in DNA synthesis dropped sharply. However, cells initiated DNA synthesis in response to the mitogenic mixture indicating that hepatocyte proliferation is controlled by G1----S transition rates.