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Biomedical subjects

L Tomenius

Publications and source records attributed to L Tomenius.

11 recordsLinked to original sources
PubMed1986

50-Hz electromagnetic environment and the incidence of childhood tumors in Stockholm County.

The magnetic fields from overhead power lines and other electromagnetic sources were determined at the birth and diagnosis dwellings of all tumor cases reported in the county of Stockholm during the years 1958-73 for individuals 0-18 years of age. The study was limited to 716 cases having a permanent address in the county both at time of birth and diagnosis. An equivalent number of controls was matched to the cases according to church district of birth, age, and sex. Outside each dwelling, the occurrence of visible electrical constructions (6-200-kV high-voltage wires, substations, transformers, electric railroads, and subways) within 150 m of the dwelling was noted. Also, the 50-Hz magnetic field was measured outside the main entrance of the dwelling. Visible 200-kv wires were noted at 45 of 2,098 dwellings and were found twice as frequently among cases as among controls (P less than .05). The magnetic field measured at the dwelling varied between 0.0004 to 1.9 microT (mean value 0.069 microT). The magnetic field was higher (0.22 microT) at dwellings with visible 200-kV wires than at those without such wires. Magnetic fields of 0.3 microT or more were measured at 48 dwellings, and were found twice as frequently among cases as among controls (P less than .05). The difference was most pronounced for dwellings of nervous system tumors and was less for leukemias.

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↗
PubMed1977

Deposition of 2- and 7-mu m particles in the rabbit lung.

Depostion of 2- and 7-mu m polystyrene particles tagged with scandium-46 and gold-198, respectively, was studied in 6 rabbits. Deposition was estimated in the 3 major bronchi and their extensions in the right lung by dissecting free the bronchial tree and measuring the radioactivity in the various sections. The rabbits were exposed to a mixture of 2- and 7-mu m polystyrene particles. The particle content among bronchi was highest in the lower lobe and lowest in the upper lobe. The average particle content per unit of bronchial surface did not differ among the bronchi or among different locations in the lobe bronchus and its extension. The ratio of 7- to 2-mu m particles was greater in all bronchial sections than in the whole lung.

Animals↗
PubMed1977

Tracheobronchial deposition of inhaled particles in rabbits.

Tracheobronchial deposition of inhaled particles in rabbit lung was studied after exposure to monodisperse aerosols 4--9 micrometer (aerodynamic diameter). Deposition was measured in terms of the particle content in free dissected bronchial sections from formaldehyde exposed and dried lungs. The free dissected part consisted of the lower section of the trachea and the lobe bronchi with their extensions from the five lobes. Deposition in this part of the tracheobronchial tree varied according to particle size, exposure technique, and individual. The range of the individual variation was about the same (300%) as the difference in deposition caused by changes in particle size (4 to 7 micrometer) and exposure technique (tracheal or oral tube). The individual variation could not be explained by any physiological factor, such as contraction in the respiratory tract. Rabbits treated intravenously with atropin had the same tracheobronchial deposition as a control group. On the other hand the individual variation in deposition could be explained by some anatomical factor since airway diameter and bronchial deposition showed a significant negative correlation.

Aerosols↗
PubMed1975

A study on tracheobronchial deposition and 2-hour retention in rabbits.

Deposition of well-defined test aerosols of polystyrene particles was studied in rabbits. The deposition was estimated in a standardized part of the tracheobronchial tree following free dissection of the bronchial parts. Ten rabbits were exposed to a mixture of two test aerosols of about the same size(6-7 mum) tagged with 51-Cr and 46-Sc, respectively. There were interindividual differences in tracheobronchial deposition but a correlation (r equals 0.98) between 51-Cr and 46-Sc tagged particles. Eleven rabbits were first exposed to the 46-Sc tagged aerosol and 2 hours later to the 51-Cr tagged aerosol. In this experiment there was also a correlation (r equals 0.74) between the tracheobronchial deposition of 51-Cr tagged particles and the 2-hour retention of 46-Sc tagged particles. This result together with results from an earlier study indicate that the large interindividual differences in deposition are real and are not caused by differences in exposure technique, or in the aerosols.

Aerosols↗
PubMed1975

The influence of a carbachol aersol on the tracheobronchial deposition of 99mTc tagged particles.

The tracheobronchial deposition of inhaled 99mTc tagged teflon particles of 6 mum (specific density 2g/cm3) was determined in rabbits by comparing the particle content in free dissected parts of the tracheobronchial tree with that in the whole lung. There was a singificantly larger deposition of particles in the proximal parts of the airways in rabbits exposed to an aerosol of the bronchoconstrictor compound carbachol than in control rabbits exposed to distilled water alone. The resistance to insufflation of a constant volume of air increased during the exposure to the carbachol aerosol, indicating bronchoconstriction. There was reproducible interindividual differences in bronchoconstrictor response to the carbachol aerosol. They were attributed to interindividual differences either in deposition of carbachol or in bronchial muscle sensitivity to carbachol. It is concluded that bronchoconstriction might serve as a defensive measure in causing a more proximal deposition of inhaled particles.

Aerosols↗