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Biomedical subjects

B Holma

Publications and source records attributed to B Holma.

At least 19 recordsLinked to original sources
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↗
PubMed1989

pH- and protein-dependent buffer capacity and viscosity of respiratory mucus. Their interrelationships and influence on health.

The macromolecular proteins (greater than 100,000 daltons) have proved mainly responsible for the protective power of mucus against penetration of the H+ ion into the surrounding tissues. This fraction is also mainly responsible for the buffer capacity and, owing to its content of glycoproteins, for the pH-dependent viscosity of mucus. Viscosity determinations, both on native sputum and on reconstituted human alpha-acid glycoprotein, indicate that either raising or reducing the pH from neutral results in an increase in viscosity. The results suggest that individuals with low pH and/or a low protein concentration (less than 6 mg ml-1) or low buffer capacity (less than 3 mumols H+/pH unit) in their mucus, i.e. a low protective power of their mucus, will risk effects released from the underlying tissues when exposed to acidic pollutants. Alternatively, persons with higher concentrations of mucus proteins will risk effects caused by increased mucus viscosity. Sputum was tested from six smokers without any symptoms other than the ability to clear their throats easily.

Buffers↗
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

Effects of inhaled acids on airway mucus and its consequences for health.

The high molecular fractions, i.e., greater than 100,000 dalton, are found to be most responsible for the H+ ion absorption capacity of the mucus in the respiratory tract. This function serves as a protection against the penetration of the H+ ion to the surrounding tissue. Acidifying mucus with a high concentration of protein, mainly glycoproteins, results in increased viscosity, which affects various lung functions. After acid saturation of the mucus, the H+ ion will react with the epithelial tissue, which results in increased permeability and a variety of effects. Acidic mucus or mucus with a low protein concentration, as in some asthmatics, constitutes a base for risk groups regarding acidic exposures. A rough estimate indicates that persons with normal mucus buffer capacity and protein content can tolerate about 3000 micrograms SO2/m3 or 300 micrograms H2SO4/m3 per 30 min.

Acid Rain↗
PubMed1985

Influence of buffer capacity and pH-dependent rheological properties of respiratory mucus on health effects due to acidic pollution.

Respiratory mucus is found to be a barrier to the penetration of H+ ions into the surrounding tissues. These ions are captured and bound in the mucus, e.g. as H-bond cross-linkages between the molecules. They increase its viscosity, which has a bearing on the mucociliary transport, airway resistance and gas exchange. The ability to bind the H+ ions is dependent on the buffer capacity and pH value of the mucus. Persons with acid-saturated mucus (some asthmatics and bronchitics) constitute a risk group, for whom effects can be more easily triggered from the surrounding tissues than in persons with mucus of higher pH. The latter primarily react only by changes of the mucus viscosity, which has a minimum near pH = 7.4. This, together with the mucus buffer capacity, appears to constitute the basis of the health effects reported from experimental studies. A simple test for evaluating the expected sensitivity of persons to acidic pollution is described.

Absorption↗
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↗
PubMed1979

Air pollution, hygiene and health of Danish schoolchildren.

A comprehensive investigation forming part of a joint European study under the auspices of "WHO Long-Term Air Pollution Programme" uses 7-13 year old schoolchildren as the target group. The study has included social, housing, hygienic and epidemic factors as well as family smoking habits. The results indicate that, at exposure to low levels of air pollution, these factors dominate as causes for the impairment of health especially that of respiratory health.

Adolescent↗
PubMed1979

Effect of trichloroethylene on cilia activity in rabbit trachea.

The ciliotoxicity of trichloroethylene was studied in terms of the time required for ciliostasis in specimens of trachea from 35 male rabbits following exposure of the specimens to different vapour concentrations. The highest vapour concentration was linked with the most rapid ciliostasis but even in the lowest concentration tested, 5.000 p.p.m. (26 g/m3), hastened ciliostasis. Specimens from the upper region of the trachea underwent ciliostasis more slowly than did those from the lower region. The absolute uptake of trichloroethylene was lower in the former than in the latter specimen. The difference in uptake could not be explained by a difference in weight or in lipid content. That ciliostasis occurred at different times depending upon the region of the trachea, favours the theory of a critical tissue concentration for trichloroethylene.

Animals↗
PubMed1976

Method for determination and element analysis of particulate contamination in injectable solutions.

A method for sampling and evaluating the chemical and physical composition of particles in injectable solutions was developed. The technique facilitates detection of the particles' sources and possible medical hazards. Particles exceeding 0.2 mum are collected on a membrane filter sized for direct application in a scanning electron microscope (SEM). The sampling device shortens the distance between filter and solution and minimizes contamination from the filter holder. Following coating of the membrane filter with gold, the particles are counted by screening at a magnification of 5,000 x in the SEM. Both unused membrane filters and filters through which a solution of 0.9% sodium chloride had been passed were analyzed. X-ray analysis of particles on the clean filter revealed silicon, aluminum (artifact from the stud) and calcium. X-ray analysis of the filter after passage of 1 liter normal saline revealed chromium, copper, iron, magnesium, manganese, aluminum (from study), calcium chlorine, sodium and silicon. Recommendations for standard procedures for particle detection in large-volume injectables are given.

Drug Contamination↗