Localization of ATPase in bovine retinal outer segments.

Highly purified bovine retinal outer segments are isolated by centrifugation. Localization of ATPase is studied with three preparations including intact, shocked (1 min in water), and lysed (10 min in water) outer segments. The activity of Mg²⁺-ATPase is equally high in these preparations. Na⁺, K⁺-activated ATPase is negligible in intact outer segments but is about 10-fold higher in the shocked and lysed preparation. K⁺-stimulated phosphatase shows a similar distribution except that the activity is higher in lysed outer segments as compared to the shocked ones. These data indicate that the discs contain a Na⁺, K⁺-activated ATPase with the ATP site on their external surface. ATP-binding assays also support the interpretation. The enzyme would accumulate Na⁺ ions into the discs and transport K⁺ ions out of them.     

Tamoxifen-induced DNA adducts in leucocytes of breast cancer patients

Tamoxifen-induced DNA adducts were searched in leucocyte DNA from breast cancer patients. Total white blood cell DNA from tamoxifen- treated and control patients was analysed by 32P-postlabelling using HPLC-radioactivity detection. Rat liver DNA was used as a positive standard. In blinded analysis four of the six treated patients showed DNA adducts; none of the five controls were positive. The identity of fraction as a tamoxifen adduct was confirmed by using different chromatographic systems, each with spiked rat liver samples. The level of adducts in the treated patients was 5.5 adducts/10(9) nucleotides as compared to an apparent level of 1.9/10(9) in the controls.      

Perinatal mortality distributed by type of hospital in the Central Hospital District of Helsinki, Finland

In Finland as in many other countries, perinatal mortality is higher in those institutions having a higher level of care. To explain this phenomenon, mortality by weight groups was studied in different hospitals in the Central Hospital District of Helsinki in Finland in 1977-81. Among infants weighing less than 2 500 g, perinatal mortality was higher in the local hospital than in the university hospital, the higher mortality being due to the higher rate of stillborn infants. Among babies weighing over 2 500 g, the mortality was lower in local hospitals than in the university hospital. Further studies to explain the higher mortality of infants weighing over 2 500 g in the university hospital are needed.     

Nationwide data base on medically diagnosed spontaneous abortions in Finland

The content and technical quality of the Finnish data base on medically diagnosed spontaneous abortions, retrieved from hospital discharges and polyclinic records, are described. The validity and suitability of the data for epidemiological studies is also evaluated. The rate was 8.9 in 1973-83 and it increased from 7.8 to 10.2 during the study period. The rates are at the same level as the ones obtained in other register-based studies, and slightly lower than those of the interview studies. A comparison of self-reported spontaneous abortions to those in our data base showed that 20% of all the abortions reported by the nurses, and 17% of those by the solvent-exposed women, were not found in the hospital register. About half of these are likely to be due to erroneous personal identification codes in the records of the patients. The absence of a spontaneous abortion was related to the length of gestation, with early abortions more often missing. Women in different occupational groups confirmed spontaneous abortions retrieved from our data base to a different degree: nurses in 91% of the cases, whereas industrial workers in only about 79% of the cases. Confirmation was also related to time elapsed since abortion. As the nationwide data base on medically diagnosed spontaneous abortions provides data, independent of an individual's own definition, recognition and reporting, it is a powerful tool in retrospective reproductive studies. Its limitations regarding early abortions need to be recognized, however.     

Postlabeling and immunoassay analysis of polycyclic aromatic hydrocarbons--adducts of deoxyribonucleic acid in white blood cells of foundry workers

Blood samples were obtained from volunteers who were occupationally exposed to polycyclic aromatic hydrocarbons in a Finnish iron foundry and from referents not known to be occupationally exposed to this class of chemical carcinogens. Aromatic adducts were determined in the deoxyribonucleic acid of white blood cells from the exposed workers with the 32P-postlabeling and immunologic techniques. There was a correlation between the estimated exposure in a particular job and the adduct levels. Jobs of men with high adduct levels (greater than 1 adduct/10(7) nucleotides in the postlabeling assay) included sand preparation, molding, shake-out, and transport. The adduct levels were low in men in pattern making, melting, and fettling. This study suggests that 32P-postlabeling and immunoassay may be useful in monitoring human exposure to known and previously unidentified environmental genotoxic agents.     

The Effect of Maternally Inhaled Styrene on Embryonal and Foetal Development in Mice and Chinese Hamsters

Abstract: Pregnant mice and Chinese hamsters were exposed to styrene 6 hrs daily during the period of major organogenesis via inhalation in concentrations 250 p.p.m., and 300, 500, 750 and 1000 p.p.m., respectively. Both in mice and in Chinese hamsters embryotoxicity was raised. Some minor skeletal malformations (rib fusions, extra ribs) were noted in mice but not in Chinese hamsters.     

Diuretics in pregnancy: A case study of a worthless therapy

In the 1960s and 1970s diuretics were used during pregnancy to prevent and treat toxemia, but this therapy is now widely condemned as ineffective and harmful. The purpose of this paper was to study this example, to learn from it and to help to prevent further such examples. Data sources included selected articles in medical journals and text-books; in Finland drug catalogues, handbooks, unpublished sales data and interviews and questionnaires to physicians; in Sweden drug catalogues and sales data; controlled clinical trials were also analyzed. Analysis of the controlled clinical trials suggested that the whole episode of wide-spread diuretic use in pregnancy could have been avoided, if the available information had been used. A reason for the neglect of the critical information was apparently that the use of diuretics was in accordance with the common medical reasoning which values changes in clinical signs rather than looking for better health indicators. Use of diuretics was condemned in Finland later than, for example, in the United States, and decline in use occured prior to the warnings in the local literature. Changes in practice seem to have occurred hierarchially and locally: opinions of a few leading obstetricians were crucial and they were rapidly and effectively disseminated to the providers of antenatal care in the domain of each obstetrician. This hierarchial dissemination of information has profound consequences for the attempts of understanding and influencing the prescribing habits of physicians.