Long-range transport of persistent organic compounds by air and ocean currents from industrialized areas resulted in high levels of these pollutants in food webs in the Svalbard area. With the aim to test if organochlorine (OC) exposure in free-living polar bears from Svalbard affected their plasma steroid hormone concentrations, it was found that polychlorinated biphenyls (PCBs) were associated with increased progesterone levels in females. The sum of pesticides (∑pesticides) and ∑PCBs contributed significantly negative to the variation of the plasma testosterone in males, and the overall contribution of the OCs to the plasma cortisol variation was negative. A second objective was to study the effects of selected OCs (i.e., PCB 153 and PCB 126) on animal health as a consequence of effects on endocrine-regulated functions such as reproduction and immunity in a goat model focusing on long-term and low-level exposure during the periods of fetal development and in the neonatal period. Additionally, acute exposure was studied in adult mice. The results indicated that exposure to low doses of PCB 153 in utero and in the suckling period influenced reproductive functions and both PCB 153 and PCB 126 exerted immunomodulatory effects on the offspring, whereas acute exposure of adult mice had minor effects on male reproductive function.
DNA repair processes of various types are well preserved through evolution reflecting their importance both for the individual and for the species. All cell types in the human body repair their DNA, although the efficiency may vary. There is little reason to assume that germ cells represent an excep...
Experimental infections of Babesia microti in laboratory-reared Clethrionomys glareolus revealed that approximately 15% of the erythrocytes were infected with single ring forms during peak parasitemia. Infected erythrocytes could be detected in blood smears up to one month post infection. C. glareolus treated with a single injection of Depo-Medrol i.m. two days prior to infection displayed a four-fold increase in number of infected erythrocytes at peak parasitemia, 35% of which contained more than one Babesia, and a prolongation of the infection. B. microti infections in 35 laboratory--reared Lemmus lemmus were fatal. Multiple invasion of erythrocytes, anemia, icterus, hemoglobinuria, anorexia and weight loss, and adrenal and splenic hypertrophy were characteristic for B. microti infections in Norwegian lemmings.
Two populations of lemmings in 6 m2 indoor pens, provided with surplus food, were characterized by increase, peak and decline phases. The founding females in both populations produced 16-18% of all litters. The sex ratio at birth was approximately 1:1 but as the populations increased there became an excess of females among the adults. Growth rates of animals older than 35 d were similar during the various phases of population development. The mean individual growth rate was considerably greater than in our stock colony and may reflect a selection for fast growers. For both sexes there was a tendency for a single individual to be heaviest, and these animals also appeared to be socially dominant. The population increase phase was characterized by high survival rates, good reproduction success, relatively low post-natal mortality and little overt agonistic behavior. During the peak phase there was relatively more overt agonistic behavior and fighting. In the peak and decline phases reproductive success was poor, and preand post-natal mortality was high. Animals which died before weaning showed lower growth rates already during their first few days of post-natal life. Biting, often followed by infection, appeared to be one of the main mortality factors for both young and adults. Pathological conditions such as fatty infiltration of the liver, ascites and internal hemorrhage were observed. Several of the observed physiological and behavioral changes occurred more frequently in the decline than in the increase phase indicating that these changes are not direct functions of population density per se.
Three virus strains serologically related to the California encephalitis group (Bunyaviridae) of arboviruses were isolated from 7331 mosquitoes collected in Norway in June-August 1975. Two of the isolates (S 548 and S 618) seemed to be closely related and the third, S 568, more distantly related by serological techniques to Tahyna virus. Viruses were found in the mosquito species Aedes sticticus, A. diantaeus and A. hexodontus colllected (in order) from Oyern (59 degrees N, 11 degrees 12' E), Trandum (60 degrees 08' N, 11 degrees 10' E) and Masi (69 degrees 26' N, 23 degrees 39' E). The Masi isolate seems to be the northernmost arbovirus isolate in the world so far. Strain S 568 was from 16 male A. diantaeus, indicating transovarial transmission of the virus. An accidental infection demonstrated the potential human pathogenicity of one of the newly-isolated strains (S 568), and the ability of CE viruses to persistently infect suckling mouse brains was indicated by in vivo findings. The biological characteristics of the new strains so far investigated are consistent with those of the California encephalitis group. During this work the Aerosil absorption method for production of haemagglutinating antigens proved useful for Tahyna virus and the newly-isolated strains. Trypsinization of erythrocytes improved the haemagglutinating capacities of these viruses.
Isolated lung cells constitute a valuable system for studying mechanisms involved in chemically induced toxicity in the lung. Different lung cells isolated from various species may be studied. Bronchiolar Clara and alveolar type 2 cells produce important lung-specific proteins, hold a major role in the metabolism of xenobiotics and serve as progenitor cells for other lung cell types. They are possible target cells in lung carcinogenesis. Alveolar macrophages play an important role in lung defence and in inflammatory responses. In the present study we have characterised chemically induced DNA damage, apoptosis, changes in cell cycle progression, transformation and alterations in gene expression in these specific lung cells isolated from rat, rabbit and human. Major differences between the cell types and the various species in the induction of DNA damage by chemicals were found, as measured by the 32P-postlabelling and alkaline filter elution techniques. Benzo(a)pyrene and hydrogen fluoride were found to induce apoptosis in the isolated cells as measured by microscopical analysis and flow cytometry. The function of various important tissue- or cell type specific proteins (CYP 2B1, Clara cell protein) and/or cellular signal transduction pathways constitute important targets that may be affected by exposure to toxic compounds. Using immunological and molecular techniques the differential expression of specific proteins/RNAs and their activity can be studied. Among other proteins, c/ebp is involved in the regulation of transcription at the end of signal pathways. The protein is differentially expressed in rat lung cells and thus could be suitable for studying differential toxic effects in various lung cells. In humans, bronchoalveolar lavage (BAL) fluid from human volunteers can be readily obtained and examined after exposure to different chemical compounds. An increase in the percentage of CD3-positive cells (T-lymphocytes) was found after exposure to hydrogen fluoride. The number of certain cell types and cytokines may be used to estimate the degree of inflammatory reaction. In conclusion, the use of in vitro data including the use of specific, primary human lung cell types may contribute considerably to the quality of risk assessment, together with in vivo data from animals and man.
