Biomedical subjects

S A Thorén

Publications and source records attributed to S A Thorén.

8 recordsLinked to original sources

PubMed1992

Calorimetry: a new quantitative in vitro method in cell toxicology. A dose/effect study of alveolar macrophages exposed to particles.

A short-term toxicological test has been developed using a calorimetric method. The metabolic activity, observed as the heat exchange rate, was monitored from alveolar rabbit macrophages in monolayers exposed to different metal and non-metal particles. Calorimetric activity indices and viability indices were introduced, from which toxic effects could be assessed. Manganese dioxide particles were found to be cytotoxic. In contrast, titanium dioxide particles seemed to be harmless. The results were in accordance with the cell survival found by use of a fluorescein ester staining method and measured by an image analyzer. Toxic effects from quartz in the form of increased metabolic activity of exposed cells could be detected by the calorimeter in contradiction to the use of the image analyzer. This latter result supports the hypothesis that silica particles cause chronic modification of the macrophage function and that this change in the alveolar macrophage function may be the first of a series of processes leading to pulmonary fibrosis.

Animals↗

PubMed1990

Heat conduction microcalorimetry of overall metabolism in rabbit alveolar macrophages in monolayers and in suspensions.

A technique has been developed for studying the overall metabolism in small numbers of cells in monolayers and in suspensions by measuring the heat exchange rate with a thermopile heat-conduction microcalorimeter. The system was tested with alveolar macrophages from rabbits, and heat flux-time curves could be monitored from numbers of cells as low as 0.05 . 10(6). The metabolic activity was found to be unchanged or to decrease very slowly over a period of 20 h. In a conventional cell medium, without the addition of serum, a mean heat flux value of 19.4 (S.D. 3.2) pW. cell-1 (37 degrees C, pH = 7.4) was obtained for alveolar macrophages in monolayers. The corresponding value for cells in the same medium, with the addition of 20% homologous rabbit serum, was 27.0 (S.D. 2.0). We suggest that this calorimetric method can be used as a short-term cytotoxic test for measuring potentially toxic agents in our environment; this test can involve alveolar macrophages of either animal or human origin. In such an assay, the cells should be used in monolayers, and suspensions should be avoided. We found that when alveolar macrophages were used in suspension, the metabolic activity, measured as heat flux, was dependent on cell concentration, even at values as low as 0.2. 10(6) cells per ml.

Animals↗

PubMed1990

A microcalorimetric vessel for monitoring cytotoxic reactions in the micro-submicrowatt region.

A microcalorimetric vessel for monitoring the initial phases of cytotoxic reactions in the micro-submicrowatt region has been designed and tested. The vessel is intended to be used with a multichannel microcalorimetric system from Thermometric, Järfälla, Sweden and can be built up stepwise in a modular way. The different functions of perfusion, stirring and addition of small amounts of soluble immune reactants can be used separately but also in combination. This is accomplished by the use of a vertical stirring mechanism and a reaction vessel of low volume, 200 microliters. The simplicity of the vessel permits an identical vessel to be used on the reference side, handled in parallel with the measuring vessel. No gas phase is present.

Calorimetry↗

PubMed1989

Operation of a multichannel microcalorimetry system in the micro-submicrowatt region: some methodological aspects.

Monitoring heat flux values below approx. 4 microW requires in microcalorimetry non-standard experimental procedures in order to achieve high accuracy and reproducibility. With 5 ml ampoules, stable baselines are reached in 70 min if a three-level pre-thermostating procedure is used and if the gas phase above the liquid is reduced to 0.5 ml or less. A pairwise procedure of reference/measuring ampoules is used. Autoclaved sealing material of teflon, sterilized stainless steel ampoules in contact with a standard cell medium and culture plates of polystyrene do not contribute to measured heat flux. Further, we found that a standard cell culture medium develops a significant thermal heat flux, 0.10 microW.ml-1, probably reflecting an oxidation process in the medium itself.

Calorimetry↗

PubMed1989

A semiautomatic image analyzer for cell counts in monolayers. I. Construction, experimental procedure, and precision obtained.

A simple, flexible, low-cost image analyzer system is presented for determination of the total number of cells and the number of viable cells in monolayers of nonconfluent cells. Viable cells were identified and counted using an immunofluorescence method using fluorescein diacetate. Alveolar macrophages from rabbits were used. The different possible counting procedures that could be performed are analyzed. The precision of the method of estimating the cell numbers is indicated by a coefficient of variation of 5%. The experimental procedure is given for a short-term toxicological in vitro test in which the semiautomatic counting procedures can be performed within 1.5 h.

Animals↗

PubMed1989

A semiautomatic image analyzer for cell counts in monolayers. II. Application to toxicity estimation and comparisons between two cell-viability markers, fluorescein diacetate and lactate dehydrogenase.

By using an image-analyzer system, toxicological effects of different substances on nonconfluent cells in monolayers can be assessed. The total number of cells and the number of viable cells are semiautomatically counted. Fluorescein diacetate is used as the viability marker. The method was tested by using monolayers of alveolar macrophages from rabbits exposed to manganese dioxide particles. A dose-response curve was obtained from a series of experiments in which the response at a certain dose level can be obtained from cell-counting procedures of the duration of 1 h. The method can be used as a short-term test, testing potentially toxic substances including cytostatic drugs where the viability should be determined. Another example is further given of the use of this technique. The results obtained from it are compared with estimates of the percentage of viable cells assessed by extracellular lactate dehydrogenase from nonexposed and manganese dioxide particle-exposed monolayers of rabbit alveolar macrophages. The two methods both account well for the theoretical relation when the lactate dehydrogenase activity values are corrected for an inactivation of this enzyme with time.

Animals↗

PubMed1989

A semiautomatic image analyzer for cell counts in monolayers. III. Statistical considerations.

The image-analyzing system described in the companion paper (Thorén and Lanke, 1989) is considered from a statistical point of view. Special attention is given to the following applications: simple cell counts, viability estimation, and toxicity estimation. Different estimators are considered, their variances are discussed, and it is shown how to compute standard errors in different situations.

Analysis of Variance↗

PubMed1983

Identification of viable and nonviable cells in scanning electron microscopy.

A method is presented for identification of viable and nonviable cells in scanning electron microscopy by use of maps of colored light micrographs of conventionally stained monolayers of alveolar macrophages. The content of phagocyted metal particles in relation to the cell viability can be estimated by using a scanning electron microscope combined with an energy-dispersive X-ray analyzer. This method makes it possible to assess the toxic effects of different air pollutants in combinations occurring in the general environment and different working conditions.

Air Pollutants↗