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At least 181 records · Page 10Linked to original sources

Environmental monitoring: correlating air measurements of substances with immune response.

In summary, data from animal models would suggest that air measurements of substances can be correlated with immune response, be it immunodepression or either of the two forms of immunostimulation-autoantibody formation or specific immunologic sensitization. However, became immunodepression and autoantibody formation are not specific for a given substance, and because they can be induced by a variety of other factors such as drugs and intercurrent viral infections, it would seem unlikely that correlations between air measurements and measurements of immunodepression or autoantibody formation could be very useful. In contrast, specific immunologic sensitization is a response that can only be induced by exposure to a specific agent. The major problem confronting investigators attempting to perform concentration-response studies in humans is accurate measurement of workplace exposures. If exposures could be reliably quantified, it is likely that concentration-response correlations could be determined for worker groups. This could prove useful for estimating exposure of groups based on aggregate immune response. It would be most useful, however, for determining threshold concentrations below which a very low proportion of workers--perhaps 1 in 100 or even 1 in 1000--would become sensitized. These threshold concentration levels of sensitizing substances could be used to develop permissible exposure levels in the workplace. Reducing workplace sensitization and diseases such as occupational asthma and hypersensitivity pneumonitis would be of obvious benefit to workers, management, government, and society at large.

Air Pollutants, Occupational↗

Hormonal correlates of environmentally induced metamorphosis in the Western spadefoot toad, Scaphiopus hammondii.

Tadpoles of several amphibian species have been shown to accelerate metamorphosis when their ponds dry. To understand the proximate mechanisms that mediate the developmental response to pond drying, I analyzed changes in endocrine activity in tadpoles of the Western spadefoot toad (Scaphiopus hammondii) exposed to experimental water volume reduction in the laboratory. Tadpoles exposed to a declining water level accelerated metamorphosis compared with tadpoles raised in a constant high water environment. The acceleration of development was associated with the precocious elevation of whole-body contents of the hormones that control metamorphosis, the thyroid hormones thyroxine (T4) and triidothyronine (T3), and the interrenal steroid corticosterone (CORT). The precocious activation of the thyroid system preceded external morphological change (i.e., increase in hind limb length, developmental stage) by 3 days. To test if tadpoles are capable of responding rapidly to water volume reduction, mid-prometamorphic tadpoles (Gosner Stage 37-38) were raised in a constant high water environment (10 L) and then transferred to either 1 or 10 L. Tadpoles transferred to 1 L exhibited significant metamorphic changes by 48 h after transfer. In addition, dramatic elevations in whole-body T4, T3, and CORT contents were evident at this time point. Thus, the metamorphic response to pond drying is likely driven by the activation of the thyroid and interrenal axes, the hormones of which control metamorphosis. Furthermore, this response is rapid, occurring within 48 h after exposure to the desiccating environment.

Animals↗

Clinical correlates of environmental endocrine disruptors.

Endocrine disrupting chemicals (EDCs), such as environmental estrogens, are hypothesized to be associated with a global decrease in sperm counts, other male reproductive tract problems and increasing rates of female breast cancer. Results of human population studies do not support the association between certain organochlorine EDCs and female breast cancer. Moreover, there is minimal evidence linking EDCs or exposure to other environmental chemicals with male reproductive tract problems. With the exception of the increasing incidence of testicular cancer, it is also questionable whether male reproductive tract problems are increasing, decreasing or unchanged. However, several studies report large differences in sperm count and quality and other endocrine-related problems within countries and regions, but the environmental, dietary and/or lifestyle factors responsible remain unknown.

Animals↗

Genetic aspects of communication during male-male competition in the Madagascar hissing cockroach: honest signalling of size.

Male Madagascar hissing cockroaches, Gromphadorhina portentosa, engage in agonistic contests with other males and produce audible sounds or 'hisses' during these interactions. Hisses are used to maintain, rather than to establish, social relationships among males. The agonistic hisses of males are variable and could be used as signals to communicate size or competitive ability of an individual. In this study we examined how size influences male-male competition, as well as the genetic variation and covariation of male body size and components of the agonistic hiss. We found that male size affected the outcome of agonistic interactions between pairs of males: a male that dominated in a pair was significantly larger than the male that was subordinate. However, we found no differences in the hisses produced by dominant and subordinate males after controlling for male weight. We estimated heritabilities, evolvability and genetic correlations for male size and characteristics of the hiss from a full-sib analysis of brothers. The patterns of heritabilities and evolvabilities were very similar. The heritabilities of both male weight and duration of the hiss were significantly greater than zero. There was a significant positive genetic correlation between duration of the agonistic hiss and male weight, and a significant negative genetic correlation between hiss duration and the beginning dominant frequency. There was also a positive phenotypic correlation and a negative environmental correlation between male weight and hiss duration. Thus, hiss duration can signal the present influence of the environment on male size, whereas information from hiss duration and beginning dominant frequency can signal the male's ability to transmit genetic influence for size.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Environmental sample correlation with clinical and historical data in a friction product exposure.

Asbestos has been widely used in the past as a component in friction products. A unique setting of dust exposure to such products occurs when individuals are involved with refabrication of the worn components. It is of interest whether asbestos fibers are released from friction materials in the use phase and the postlife phase or if the mineral fibers are converted to a nonasbestos form. In the present study, an individual whose primary work activity had centered on clutch refabrication was evaluated for possible dust-related diseases. Tissue analysis revealed the presence of large numbers of asbestos fibers as well as ferruginous bodies. These particulates were characterized as to composition as well as dimensions. Clutches of the type typically used by this individual were obtained and material was rinsed from their surface for comparative purposes. Materials that were freed from the surface and reviewed by analytical transmission electron microscopy were clearly identifiable as chrysotile asbestos. The composition of the clutch material was compared with the components found in the patient's lung tissue. The conclusion from this comparison was that individuals exposed to friction materials under similar circumstances should use appropriate caution. Appreciable exposure to asbestos can occur and this exposure can be sufficiently high to result in disease.

Air Pollutants, Occupational↗

Correlation between environmental monitoring of thermophilic campylobacters in sewage effluent and the incidence of Campylobacter infection in the community.

Environmental monitoring of thermophilic campylobacters in liquid sewage effluent (primary settlement only) during 1988 and 1989 showed a prominent seasonality with distinct peaks in May and June (the average number of bacteria per 100 ml of effluent in months other than May and June was 2244 and the average for the peak months was 50,778). Apart from September 1989, this seasonality coincided precisely with the seasonal variation of campylobacter enteritis in the community with similar distinct peaks in May and June (the incidence of infection in May and June was twice or three times that in the other months). Sampling of sewers showed that the campylobacters in the sewage effluent came mainly from abbatoir and animal processing plants with only a minor input from the community. Therefore, the seasonal peaks in the sewage effluent and in the community may not be dependent on human infections but on zoonotic infections which may also peak in May and June.

Abattoirs↗

Atopic dermatitis. Correlation of environmental factors with frequency.

Answers to a questionnaire on atopic dermatitis sent to clinicians in different countries--excluding Europe and North America--were evaluated. The questions included frequency as well as the possible role of special influencing/aggravating factors in atopic dermatitis patients. According to the data from 19 different countries, climatologic/geographic conditions, profession, and psychic stress have a decisive role, whereas food items have a smaller role in the course of atopic dermatitis.

Africa↗