Biomedical subjects
Publications and source records attributed to E D Palmes.
A field test of two sampling methods for the determination of NO2 concentration in air is reported. All samples were collected in an underground salt mine in which diesel equipment is operated. Although each method has it own advantage, both appear to be suitable for most industrial hygiene applications.
A personal sampler system for NOx (NO + NO2) and NO2 has been developed for monitoring workplace air. The NO2 sampler previously reported from this laboratory uses triethanolamine to trap NO2 which diffuses through a tube of appropriate dimensions. The NOx sampler contains the same elements as the NO2 device, but it is also fitted with a chromic acid impregnated disc; this disc converts NO to NO2 which is then trapped by the triethanolamine along with preformed NO2. The trapped NO2 in all cases is determined as nitrite colorimetrically and NO is measured by difference between the NOx and NO2 values. The NOx sampler gives accurate and reproducible results if the chromic acid disc is in place for 24 hours or less; it is necessary, therefore, to insert and remove the disc within reasonably short times before and after sampling. We believe, however, that this operation will not be a serious problem for the user.
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It has been shown that S-sulfonate compounds (R-S-SO-3) are produced by the action of sulfite on reactive disulfide bonds [4,5]. Plasma S-sulfonate production was determined as a function of sulfite ingestion and intraperitoneal injection in rats, mice and rhesus monkeys. The tendency of these species and of the rabbit [8] to produce S-sulfonates in plasma was related to the availability of sulfite and of reactive disulfide bonds and to the stability of plasma protein S-sulfonates. The rhesus monkey and the rabbit accumulated plasma S-sulfonates much more readily than did the rat, while the mouse produced little, if any, under the same test conditions. Plasma protein S-sulfonate fractions in the rat and rhesus monkey were characterized by half-lives of approximately 4 and 8 days respectively. The sensitivity and precision of the analytical method for plasma protein S-sulfonate were improved by incorporation of 35S into the outer sulfur atom of the S-sulfonate moiety (R-S-35SO-3).
Four stable laboratory mouse populations were established; each contained approximately 400 mice of both sexes and all ages postweaning living in a single cage, as well as neonates caged in separate nesting boxes with their dams. Two were used to determine the effects of continuous exposure to a dietary level of 100 ppm DDT while the other two served as controls. The results indicated a significant decrease (p less than or equal to 0.05) in neonatal survival (lactation index) within 20 wk after the beginning of exposure to the toxicant in one of the exposed populations and by 30 wk in the other. This deleterious effect of the DDT continued through each succeeding generation. On the other hand, improved postweaning survival in DDT-fed mice was noted. Histological examination showed no tumors in test or control animals; other pathology was seen more frequently in control than in test animals.
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During surgical procedures in which nitrous oxide (N2O) anaesthesia was administered there was an increased concentration of both nitric oxide (NO) and nitrogen dioxide (NO2) in operating-room air. Preliminary studies suggest that the use of certain devices (e.g., electric cauteries, X-ray machines) capable of releasing energy in the operating-room produce the oxidation of nitrous oxide. Further evaluation of gas phase reactions of anaesthetic agents within the operating-room appear warranted, particularly in relation to the occupational risks of operating-room personnel.
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A new type of personal sampler for gases in air, originally reported from this laboratory, has been adapted to measurement of NO2. The sampler depends on the transfer of NO2 by diffusion to a triethanolamine coated collector at the sealed end of a tube; the open end of the tube is exposed to the test environment. The devices are accurate, light, simple to use and have very good shelf life before and after sampling.
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Measurement of persistence, expressed as half-life (t1/2), of a monodisperse aerosol during breath holding was interpreted as an indirect estimate of the size of intrapulmonary airspaces in healthy subjects. Within subject variation of t1/2 measured over a period of nearly two years was small (coefficient of variation 7-7 to 11-5%). Mean effective airspace diameters were calculated from the aerosol t1/2 values using the settling term from the equation of Landahl (1950). Calculated mean airspace diameters ranged from 0-30 to 0-79 mm for 36 males and from 0-40 to 0-62 mm for 12 females. Airspace diameters correlated poorly with age, height, weight, and lung volumes. These results suggest marked differences in airways geometry in subjects with similar heights and lung volumes.
Models used to estimate both total and regional deposition of aerosols in the human respiratory tract have been proposed by a number of individuals and groups. Although the values chosen by different investigators for dimensions of airways or other air spaces may differ significantly from each other, there is the common assumption that the normal human respiratory tract is structurally uniform and that dimensions and branching patterns may be considered as constants in the deposition equations. There has been, therefore, considerable emphasis on estimating the effects of particle size, size dispersion, tidal volume and respiratory frequency. Much less attention has been paid to the normal intersubject variability of the size of air spaces in spite of the obvious influence this would have on aerosol deposition. Work on deposition from our own laboratories, as well as published results of others on pulmonary anatomy, has lead to the conclusion that there is considerable anatomic variability among normal subjects. Aerosol deposition in individuals examined under nearly identical conditions has also shown considerable variability. This paper will discuss the similarity in range of anatomical differences and differences in deposition and the probable relationship between the two.