Search

The U.S. Radium Corporation plant in Bloomsburg, PA, was one of two major radium dial painting facilities in the United States during the post-World War II era. Victor Hess, of the Physics Department of Fordham University, was responsible for radon breath measurements from workers at this plant. His room air sample results, over 300 measurements dating from 1949 through 1966, form a unique data base for reconstructing radium dial worker radon exposures in that era. Monday morning radon levels averaged about 150 Bq m−3, well below the tolerance level of 370 Bq m−3. That average is representative of radium dial painting areas of the plant. Most areas, particularly offices and technical support areas, had radon levels comparable to local residential averages. Levels in the radium laboratory areas throughout most of the study period were above the tolerance limit; the highest location averaged 603 Bq m−3. radon levels in laboratory areas were significantly reduced in the last six years of the study, but radon levels in other parts of the plant remained relatively constant. These values, because of time of collection, may modestly underestimate radon concentrations during work hours in much of the plant and significantly overestimate it in laboratory areas.

In industrial society a large number of point sources of pollution exist, such as chemical plants, smelters, and nuclear power plants. Public concern has forced the practising epidemiologist to undertake health surveillance of the usually small populations living around point sources. Although not justifiable as research, such epidemiologic surveillance activities are becoming a routine part of public heath practice, and this trend will continue. This introduction reviews concepts of epidemiologic surveillance, and institutional problems relating to the quality of such applied research.

Over 300 elderly panelists, either well or with reported cardiopulmonary symptoms, participated in a study linking aggravation of symptoms to fluctuations in ambient air pollutants and daily temperature in New York City. Increasing temperatures aggravated symptoms in heart disease panelists; clear and consistent relationships of temperature to symptoms in the well, lung disease, or combined heart and lung disease panelists were not apparent. Elevated levels of suspended nitrates, suspended sulfates, sulfur dioxide, and respirable suspended particulates were associated with exacerbations of symptoms in the well elderly panel; a similar but much weaker pattern of effects on the lung disease panel appeared. It was not possible to identify more precisely the responsible pollutants. Symptoms of heart disease appeared to be related only to suspended nitrate and total suspended particulate levels in addition to temperature. The data did not suggest a threshold for these health effects nor did the data support the hypothesis that those panelists more severely afflicted with cardiopulmonary conditions would be more sensitive to air pollution. The effect of method of panel selection on the estimation of dose-response relationships, and the concept of day-to-day fluctuations in symptom rates were discussed.

Hook decoration with pig brain tubulin was used to assess the polarity of microtubules which mainly have 15 protofilaments in the transcellular bundles of late pupal Drosophila wing epidermal cells. The microtubules make end-on contact with cell surfaces. Most microtubules in each bundle exhibited a uniform polarity. They were oriented with their minus ends associated with their hemidesmosomal anchorage points at the apical cuticle-secreting surfaces of the cells. Plus ends were directed towards, and were sometimes connected to, basal attachment desmosomes at the opposite ends of the cells. The orientation of microtubules at cell apices, with minus ends directed towards the cell surface, is opposite to the polarity anticipated for microtubules which have elongated centrifugally from centrosomes. It is consistent, however, with evidence that microtubule assembly is nucleated by plasma membrane-associated sites at the apical surfaces of the cells (Mogensen, M. M., and J. B. Tucker. 1987. J. Cell Sci. 88:95-107) after these cells have lost their centriole-containing, centrosomal, microtubule-organizing centers (Tucker, J. B., M. J. Milner, D. A. Currie, J. W. Muir, D. A. Forrest, and M.-J. Spencer. 1986. Eur. J. Cell Biol. 41:279-289). Our findings indicate that the plus ends of many of these apically nucleated microtubules are captured by the basal desmosomes. Hence, the situation may be analogous to the polar-nucleation/chromosomal-capture scheme for kinetochore microtubule assembly in mitotic and meiotic spindles. The cell surface-associated nucleation-elongation-capture mechanism proposed here may also apply during assembly of transcellular microtubule arrays in certain other animal tissue cell types.

Panel studies relating illness, such as asthma attacks, cardiopulmonary symptoms, and acute respiratory symptoms, to daily air pollution and weather are important in environmental epidemiology. A study of the practical robustness of multiple linear regression procedures, which have been the preferred statistical models in analyses, is presented. The study is based on data from three asthma panels in Chattanooga, Tennessee, collected in 1972–1973. Linear regression models, commonly used, which incorporate only minimum temperature and an air pollutant were found to be potentially misleading; such models are highly sensitive to reporting trends in the data and do not correct adequately for weather variables. Temporal and spatial control strategies were employed and proved to be useful in detecting problems in the data due to undiscovered intervening variables. True day-to-day relationships estimated by a paired-day analysis were frequently inconsistent with “daily” effects estimated by the usual regression models and suggested that, in fact, the asthma panel data contained no useful information concerning day-to-day relationships.

Cancer among Los Alamos County, New Mexico, male residents, all of whom have worked in or have lived within a few kilometers of a major plutonium plant and other nuclear facilities, has been reviewed with respect to mortality between 1950 and 1969 and incidence between 1969 and 1974. A possible excess of neoplasms of the reticuloendothelial system was detected, but the incidence data suggest that this excess, if real, is no longer occurring. Several potentially causal occupational exposures have existed. Higher than expected incidence, currently, of cancers of the colon and rectum appears to be explained better by socioeconomic than occupational factors. Neither mortality nor incidence data suggest an excess of lung cancer in Los Alamos males. Healthy worker and healthy military effects, white ethnicity, and migration are discussed as intervening variables relevant to interpreting mortality data in counties dominated by a single major facility. The utility of county data bases in the study of single local area mortality rates is reviewed.

Noninhaling of tobacco smoke, and, by implication, use of filter cigarettes, do not appear to reduce the rate of decline of the FEV 1 with age among smokers. The cumulative benefit of not smoking in late adolescence and early adult life appears to be permanently retained despite later smoking. Workers born in Puerto Rico show distinctly lower values for the FEV 1 than other foreign or native-born workers. A possible effect of occupational exposure to air pollution among nonsmoking bus drivers was found. A number of smoking variables beyond current type and amount were shown to contribute to the prediction of the FEV 1 . It is suggested that these, and also sitting height and weight, should be accounted for in analyses of air pollution or other environmental effects on pulmonary function. The use of age and standing height in predicting the FEV 1 for mass screening purposes was shown to be only 90% as sensitive as the use of age, standing height, sitting height, and weight.

The effects of urban residence on prevalence of respiratory symptoms and on pulmonary function in a population of white male nonsmokers are presented. Residence in urban areas of 50,000 + population in childhood was positively related to the PEFR; the effect at age 21 was estimated as approximately +26 liters/min. Residence in urban areas during adult life showed a significant nonlinear relationship to PEFR. Values increased during the first 7 years of urban residence as an adult, and then declined; this effect, at 30 years of urban residence after age 21, was estimated at −44 liters/min. No effect on the FEV 1.0 was found. Results for the prevalence of cough and phlegm are consistent with the results for the PEFR, but numbers were too small to allow definite conclusions to be drawn. The variance about the regressions was studied, and it was discovered that social class and urban residence affected the relationship of the variance about the regression to the age of the respondents.

Panel studies relating illness, such as asthma attacks, cardiopulmonary symptoms, and acute respiratory symptoms, to daily air pollution and weather are important in environmental epidemiology. A study of the practical robustness of multiple linear regression procedures, which have been the preferred statistical models in analyses, is presented. The study is based on data from three asthma panels in Chattanooga, Tennessee, collected in 1972-1973. Linear regression models, commonly used, which incorporate only minimum temperature and an air pollutant were found to be potentially misleading; such models are highly sensitive to reporting trends in the data and do not correct adequately for weather variables. Temporal and spatial control strategies were employed and proved to be useful in detecting problems in the data due to undiscovered intervening variables. True day-to-day relationships estimated by a pair-day analysis were frequently inconsistent with "daily" effects estimated by the usual regression models and suggested that, in fact, the asthma panel data contained no useful information concerning day-to-day relationships.

Stebbings, J. H. (1974).Thorax, 29, 505-510. Fractional carbon monoxide uptake in an employed population. The fractional carbon monoxide uptake in 913 New York City transit workers was studied. A prediction equation for white males, based on nonsmokers, was obtained: fractional CO uptake = 0·58032 − 0·00204 × age + 0·0004 × weight (kilograms). Weight was the index of body size most strongly correlated with the fractional CO uptake. Decline in function with age by amount of tobacco smoked is described. A correction factor for respiration, based on results from 581 workers with two or more tests, was calculated: − 0·123654 × (standard tidal volume − observed tidal volume). Tidal volume was the most important contributor to individual variability of the fractional CO uptake, and minute volume or respiration rate do not add significantly to it. For epidemiological or screening uses, prediction equations are given for the fractional CO uptake corrected to 0·5 1. tidal volume. Respiration variables explain only 1·5% of individual variability, and individual variability over a mean period of 16·6 months was much larger (an individual standard error of 0·07) than the unexplained population variability (a population standard error of 0·01−0·02); thus the usefulness of the fractional CO uptake as a test of respiratory function is in doubt.

The trophozoites of Selenidium fallax propagate bending waves at rates of up to 35 μm s−1, of a similar character to those manifested by eukaryotic cilia and flagella. A beat frequency of 0·12–0·15 Hz appears average, though rates outside this range have been recorded. Translatory locomotion at up to 6 μm s−1 has been observed. The protozoan demonstrates the presence of an active bending mechanism, probably along its entire length, and a means of coordinating adjacent bends. The Reynolds number for the motion is 10−5-10−4, suggesting that the hydrodynamic aspects of the trophozoite movement are amenable to analysis by similar means to those already employed for cilia and flagella. It is possible that the protozoans exhibit a sliding microtubule mechanism, which could be very usefully compared with that occurring in the ciliary axoneme.

The telotrophic ovary of Notonecta glauca glauca consists of 7 ovarioles. Each ovanole comprises, from front to rear, a terminal filament, a trophic region, a prefolhcular region, and a series of 10-15 follicles of progressively increasing size The trophic region is largely syncytial and is made up of polyploid trophic nuclei packed around a central trophic core The cytoplasm of the trophic core is continuous with the cytoplasm of each oocyte through a system of trophic tubes. There is one trophic tube per oocyte. The trophic nuclei have large nucleoh. There are a few small nucleoh in the oocyte nuclei The cytoplasm of the trophic core, the trophic tubes, and the oocytes is rich in RNA. Autoradiographs of sections of ovarioles fixed 2 h after injection of PHjundine into animals show label over the trophic nuclei only. Eight-hour autoradiographs show heavy labelling of the trophic region and label over the front ends of the trophic tubes, but little label over the posterior regions of the tubes or the oocyte cytoplasm. Later autoradiographs indicate that label gradually spreads backwards from the trophic core, along the trophic tubes, and progressively builds up in the oocyte cytoplasm These observations are thought to indicate synthesis of RNA in the trophic region and movement of RNA from the trophic core along the trophic tubes to the oocytes The trophic core and tubes show brilliant positive form birefringence with respect to their lengths. This birefringence can be reduced by keeping animals at 2 °C for 12 h, and eliminated by placing ovanoles in 1 % colchicine for 6 h. Electron micrographs of thin sections of ovanoles show that trophic core and tubes are densely and uniformly packed with nbosomes and microtubules The latter are lined up along the trophic tubes. There are about 30000 microtubules evident m a TS through a trophic tube 15 fim wide. Lengths of microtubules up to 2 /*m have been observed. Ribosomes are packed between the microtubules but are excluded from regions where the spacing between adjacent microtubules is less than 25 ran The contribution of the trophic region to the oocytes and the role of the microtubules in maintaining or facilitating the movement of nbosomes along the trophic tubes is discussed

Ovarioles of Notonecta glauca glattca have been treated with vinblastine sulphate (VBL),primarily to examine the effects of the drug on the microtubules which pack the trophic core and nutritive tubes, 10–4 M VBL had little effect on the microtubules. VBL at 10–3 M reduced the number of microtubules in nutritive tubes, while after 2 ×10–3 M VBL microtubules were rare. All 3 concentrations of VBL induced the formation of crystalline structures in the trophic coreand nutritive tubes, and to a lesser extent in the nutritive cells and follicle cells. In transverse sections crystals appeared to be composed of distinct hexagonal units and in longitudinal sections crystals showed as dark parallel lines with darker dots at regular intervals along their length. With 10–4 M VBL, the crystals were compact and close to the walls of nutritive tubes, but after treatment with stronger concentrations of VBL the crystals were web-like and scattered over cross-sections of tubes. In addition to VBL having a destructive effect on the microtubules in the trophic core and nutritive tubes, there was also a reduction in the number of ribosomes. This overall reduction in ribosome quantity could not be attributed to the inhibition of RNA synthesis by VBL. In regions of ovarioles where microtubules were arranged in parallel masses, as in the nutritive tubes and trophic core, the long axes of crystals were always similarly aligned. Other wise crystals were randomly oriented. The possible mode of formation, and composition, of crystals is discussed.

IT is commonly believed that in areas of European colonization introduced lumbricids tend to supplant the endemic earthworm fauna. Stephenson1 gives several examples. More recently the spread of Allolobophora caliginosa in New Zealand has been documented2,3, and G. E. Gates4 has described the distribution of European species in India.