Search PubMed⌕ Search

Biomedical subjects

A Wennberg

Publications and source records attributed to A Wennberg.

At least 73 records · Page 4Linked to original sources
PubMed1980

Biological evaluation of root canal antiseptics using in vitro and in vivo methods.

Five antiseptics commonly used in endodontic treatment were evaluated with regard to cytotoxicity and initial tissue irritating effect. The cytotoxicity was evaluated in a cell culture system using HeLa cells and the initial tissue irritating effect was assessed by application of the antiseptics onto an intact nonepithelialized tissue surface. The cell response was assessed by registering changes in the DNA synthesis of the cells and the tissue response was assessed by registering changes in the oxidoreductase enzyme activity of the tissue. To evaluate the ability of the cells and the tissue to overcome an induced damage, one part of the study included a recovery period before the condition of the cells and the tissue was assessed. The most severe cell and tissue reactions were caused by 5% Chloramine-T whereas no differences in toxicity or tissue irritating effect were found between 0.04% Jodopax, 0.1% Biosept, 0.1% Hibitane, or 0.5% sodium hypochlorite. The HeLa cells showed the best recovery after having been influenced by Jodopax, Chloramine-T or sodium hypochlorite solutions, whereas the best tissue recovery was observed in the experiments with Biosept and Hibitane.

Acetrizoic Acid↗
PubMed1980

Exposure to organic solvents. A cross-sectional epidemiologic investigation on occupationally exposed care and industrial spray painters with special reference to the nervous system.

In the present epidemiologic study 80 car or industrial spray painters with long-term low level exposure to organic solvents were examined and compared with two matched reference groups of nonexposed industrial workers (80 persons in each group). The aim of the study was to investigate the possible effects of the solvent exposure on health. The investigation included psychiatric interviews, psychometric tests, neurological, neurophysiological and ophthalmologic examinations, and computed tomography of the brain. The painters' previous and present exposure was carefully assessed by interviews and on-the-job measurements both at modern places of work and in a reconstructed model of a workshop from 1955. On the basis of the psychiatric interviews the psychiatric symptoms were rated according to a specially designed scale of 46 different items, graded in seven steps of increasing severity. The psychological performance was assessed by a battery of 18 tests. The neurological and neurophysiological examinations comprised visual evoked responses (VER), electroencephalography (EEG), and computerized EEG analysis (SPA) for the central nervous system and electroneurography (ENeG), the estimation of vibration sense thresholds, and a quantified neurological examination for the peripheral nervous system. The ophthamologic examination concentrated on the condition of the lens. Statistically significant differences between the exposed individuals and referents were found for psychiatric items indicative of a slight cerebral lesion (ie, a neurasthenic syndrome). The psychometric tests revealed statistically significant differences between the groups with respect to reaction time, manual dexterity, perceptual speed, and short-term memory. No differences were found with respect to performance on verbal, spatial, and reasoning tests. Significant differences between the groups were also found for the majority of the neurophysiological parameters measuring peripheral nerve functions, the most pronounced occurring in the long, sensory fibers. Moreover EEG and VER showed some differences between the groups, as did the results of the ophthalmologic examination and the computed tomography. Finally, it should be emphasized that the exposure levels, as measured at modern places of work and in the reconstructed workshop from 1955, were found to be considerably lower than the valid threshold limit values in Sweden.

Brain↗
PubMed1979

A method for toxicity screening of biomaterials using cells cultured on millipore filters.

In the present paper a tissue culture technique is described whereby the toxicity of setting and solid materials may be evaluated. A cell monolayer was established on a millipore filter which was placed on an agar medium, cell side down. Test specimens were placed on top of the millipore filter and were allowed to influence the cells through the filter for two hours. The cell reaction was assessed by incubating the cells, still adherent to the filter, for the demonstration of succinate dehydrogenase activity. Materials with a cytotoxic effect caused a zone of inhibited enzyme activity in the cell-material contact area. The filters were examined macroscopically and scores from 0 to 3 were given to grade the severity of the cell response. Unset and set silicate cement, zinc phosphate cement and an acrylic resin were tested. The results obtained were consistent and in accordance with those of previous reports. The method was simple and rapid and appeared suitable for the assay of larger test series.

Animals↗
PubMed1979

Ameloblasts--ion transport function.

Recent autoradiographic and in vitro studies have produced evidence that the cells of the enamel organ limit the movement of calcium into enamel during the matrix secretion phase, but have no effect on movement of calcium during the maturation phase. The cells of the enamel organ do not seem to control the flux of phosphorus into enamel at either phase of development. This concept is consistent with current theories on the control of ion fluxes into developing bone.

Ameloblasts↗
PubMed1979

Long-term exposure to electric fields. A cross-sectional epidemiologic investigation of occupationally exposed workers in high-voltage substations.

In the present epidemiologic study, 53 workers with a long-term (more than five years) exposure to the electric field of 400 kV substations were examined and compared with a matched reference group of 53 nonexposed workers from the same power companies. Matching variables included age, geographic location and employment time. The aim of the study was to investigate the possibility of persistent, chronic health effects in the exposed group as a consequence of exposure. The investigation indluded the nervous system (neurasthenic symptoms, psychological tests, electroencephalography), the cardiovascular system (symptoms, blood pressure, electrocardiography), and the blood (hemoglobin, red blood cells, reticulocytes, white blood cells including differential count, thrombocytes, sedimentation rate). Fertility was also assessed. The results showed no differences between the exposed and reference groups as a consequence of the long-term exposure to the electric fields. The groups differed, however, in that the exposed group had (a) consistently better results on the psychological performance tests, (b) a fewer number of children, especially boys, and (c) somewhat higher education. The differences in test results were due to the higher education among the exposed. The difference in number of children was also thought to be related to factors other than exposure since it was found to be present already 10--15 years before the work in 400 kV substations began.

Adult↗
PubMed1978

Comparison of 33P with 45Ca distribution in developing rat molar enamel in vivo and in vitro.

The distribution of 45Ca and 33P in developing rat molar enamel has been studied using freeze sectioning and autoradiographic methods. The distribution patterns of the two tracers in vivo were dissimilar. The use of in vitro methods showed that flux of 33P into enamel is not influenced by the cells of the enamel organ. It is suggested that the factors controlling movement of calcium and phosphorus into mineralizing enamel may be similar to those proposed for bone.

Animals↗
PubMed1978

Influence of the pulpal route on uptake of 45Ca in enamel and dentin of developing rat molars.

45Ca uptake in developing enamel and dentin was studied by autoradiography. The findings indicate that the pulpal route does not supply significant amounts of calcium to the rapidly mineralizing enamel. Disruption of the odontoblastic layer did not seem to result in altered penetration of calcium into the dentin in a manner similar to that described for disruption of the matrix secreting cell layer of enamel and of bone.

Animals↗
PubMed1978

A method for evaluation of initial tissue response to biomaterials.

In the present paper an implantation technique is described whereby the effect of the surgical operation is eliminated and initial tissue reactions to materials may be studied. A teflon body was implanted intramuscularly in rabbits. After six weeks the overlaying tissue was excised and the implant removed. An intact, nonepithelialized tissue surface was exposed, which due to the shape of the implant showed three indentations. Materials were placed in the indentations for 15 minutes and the tissue reaction was registered by enzyme histochemical methods. Silicate cement, zinc phosphate cement and a 4% phenol solution caused an inhibition in the dehydrogenase enzyme activity in the tissue subjacent to the indentations. The severity of the tissue reaction, indicated by the width of the inhibition zone, varied among the test materials. Silicate cement caused the widest inhibition zone and the phenol solution the narrowest one. These results correlate well with previous tissue compatibility studies and indicate that the method is applicable for in vivo screening of initial tissue response to biomaterials.

Animals↗
PubMed1978

In vivo and in vitro study of 59Fe uptake in developing rat molars.

Autoradiographic methods were used to study 59Fe uptake in vivo in mineralizing tissues of young rats. Localization of 59Fe was observed in the ameloblastic layers of molars. In vitro studies were performed which demonstrated that 59Fe uptake in developing rat molar enamel was limited by the metabolic activity of the cells of the enamel organ.

Animals↗
PubMed1978

Long-term exposure to jet fuel. II. A cross-sectional epidemiologic investigation on occupationally exposed industrial workers with special reference to the nervous system.

Thirty jet fuel exposed workers selected according to exposure criteria and thirty nonexposed controls from a jet motor factory were examined, with special reference to the nervous system, by occupational hygiene physicians, psychiatrists, psychologists, and neurophysiologists. The controls and the exposed subjects were matched with respect to age, employment duration, and education. Among the exposed subjects the mean exposure duration was 17 years, and 300 mg/m3 was calculated as a rough time-weighted average exposure level. The investigation revealed significant differences between the exposed and nonexposed groups for (a) incidence and prevalence of psychiatric symptoms, (b) psychological tests with the load on attention and sensorimotor speed and (c) electroencephalograms. When the control group was selected, it was ensured that the two groups were essentially equivalent except for exposure to jet fuel. It is concluded, therefore, that the differences found between the groups are probably related to exposure to jet fuel.

Adult↗