Biomedical subjects
Publications and source records attributed to A D Kappos.
For evaluation of the carcinogenic potency of an environmental chemical or a mixture of chemicals, epidemiological or workplace studies, animal studies, and in vitro tests are the three major strategies used. Asbestos fibers and 1,2-dichloroethane are chosen as examples. They illustrate that the strategies may enable the implementation of measures by health authorities.
Indoor air pollution is characterized by a wide range of concentrations of many, mainly organic substances. To avoid adverse health effects it is necessary to develop indoor air quality standards. Standards should reflect the way and time of exposure and the fact that health risks might be possible especially to sensitive people. The toxicological basis for regulating indoor air quality is discussed. Special attention is given to organic substances with a cancerogenic and accumulating potential. An approach in setting standards of indoor air quality for frequent organic substances like toluene, xylene, styrene, dichloromethane, 1.1.1-trichloroethane, trichloroethene, tetrachloroethene, pentachlorophenol and PCB is presented, incorporating adequate protection margins. The results of this approach are compared with the WHO air quality guidelines and the German MIK values.
During the sunny summers of 1989 and 1990 in Germany the outdoor ozone levels repeatedly exceeded the value of the air quality guidelines proposed by the World Health Organization. Both in multiple sites within industrial polluted and in supposedly clean outside areas the ozone concentrations exceeded the value of 180 micrograms/m3. The following paper is intended to contribute to an understanding of the health effects of ozone. It compiles data and views on the formation and analysis of ozone, on its distribution as ambient ground level pollutant, on respiratory and common symptoms in man and on the toxicokinetics, responses and pathogenesis in experimental animals. Studies on healthy exercising adult volunteers exposed to 240 micrograms/m3 ozone in purified lab air or in ambient air revealed a significant influence on connections between forced vital capacity, forced expiratory volume, flow rate and peak expiratory flow rate and the pollutant. Exposure to lower ozone levels induced the same effects, but they were of smaller magnitude. Children aged 8-15 years exercising under field conditions showed decrements in lung function even at ozone levels well below 200 micrograms/m3. Restitution of lung function needs periods of several days, although the induction of effects is a matter of hours. The relevance of the transient pulmonary responses is widely unclear. Among patients with chronic obstructive pulmonary disease or asthma, the functional responsiveness to ozone is not greater than among healthy subjects. Interindividual differences in responsiveness occur but are not predictable. Information on chronic effects is rather limited.(ABSTRACT TRUNCATED AT 250 WORDS)
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We report on a 54-year-old patient with chronic renal failure, in whom complete AV block occurred after aortic valve replacement. During hemofiltration an external demand pacemaker sensed spikes induced by the employed machine. This caused an asystole. Fixed rate pacing re-established regular ventricular contractions.
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Total pulmonary resistance (Rt) and reactance (Xt) from 1 to 30 Hz were determined by time series analysis in open-chest vagotomized dogs. Rt and Xt were partitioned by retrograde catheter into central airway resistance (Rc) and reactance (Xc) and peripheral resistance (Rp) and reactance (Xp). Rt, Rc, or Rp did not change with transpulmonary pressure (Pst) from 5 to 15 cmH2O, although Rc tended to decrease and Rp to increase. Vagal stimulation (Vs) and intravenous histamine (H) increased all resistances (R) at all lung volumes (V) and produced an inverse relationship between R and V. The increases in Rt produced by H and Vs were not significantly different at any volume, but H predominantly increased Rp and Vs predominantly increased Rc. In the control (vagotomized) dogs at Pst of 5 cmH2O, Rp/Rt was 0.41 +/- 0.03 (SE). Rp/Rt was significantly increased by H but not by Vs. Control Rt decreased slightly from 5 to 10 Hz and increased from 15 to 30 Hz. The increase of Rt at higher frequencies caused by the frequency dependence of Rc was not changed by H but was augmented by Vs. The slope of Xt and Xc vs. frequency was increased by Vs but not by H. The frequency dependence of Rt and Xt above 10 Hz appears to be caused by inertial losses proximal to the 2-mm airways. Thus central and peripheral bronchoconstriction caused by Vs and H, respectively, could be differentiated by increased frequency dependence of Rt and Xt above 15 Hz.
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