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At least 1,225 records · Page 68Linked to original sources
PubMed1983

Occupational nitrosamine exposure. 1. Rubber and tyre industry.

To determine the role of N-nitrosamines in the known increased cancer risk of rubber workers, air concentrations of such carcinogens were measured by area sampling or personal monitoring in 19 factories. N-Nitrosodimethylamine (NDMA) and N-nitrosomorpholine (NMOR) were found regularly, the air concentrations varying between 0.1 and 380 micrograms/m3 personal monitoring. The mean concentration was usually in the range of 1-10 micrograms/m3. Several other nitrosamines could be detected in certain production branches. In retail shops and storage rooms of tyres NDMA and NMOR were found. Most rubber chemicals based on amines are contaminated with N-nitrosamines, but this contamination cannot explain the air concentrations of nitrosamines found. The occurrence of nitrosamines mainly depends upon their formation during production of rubber and rubber products from used vulcanisation accelerators based on amines and the presence of nitrosating agents, such as diphenylnitrosamine (retarder A) and of nitrous gases, in products or production areas. Elimination of one or both precursors for nitrosamine formation resulted in significant reduction of airial contamination of nitrosamines. The results are discussed in regard to the mechanisms of nitrosamine formation during rubber production, as basis for future epidemiological studies and their potential for exposure prevention.

Air Pollutants↗
PubMed1985

Indoor air pollution and its effect on pulmonary function of adult non-smoking women: I. Exposure estimates for nitrogen dioxide and passive smoking.

The potential effects of indoor NO2 and tobacco smoke on the respiratory system were studied using pulmonary function data from a longitudinal study. In 1982, NO2 was measured in 163 homes of non-smoking adult women and detailed information on smoking inside the house was gathered over the period 1965-1982. Personal exposure to NO2 was calculated from the measured levels and the activity pattern of the study population (range 11-139 micrograms NO2/m3). Historical exposure was estimated using regression models of NO2 on house characteristics. It is shown that estimation of historical exposure to indoor NO2 on the basis of house characteristics only is, at present, too inaccurate for use in epidemiological studies. Actual measurement of NO2 is unavoidable for exposure assessment in health effect studies of indoor exposure to NO2.

Adult↗
PubMed1985

Indoor air pollution and its effect on pulmonary function of adult non-smoking women: II. Associations between nitrogen dioxide and pulmonary function.

The association between nitrogen dioxide levels in homes and pulmonary function of 97 non-smoking adult women was investigated in a rural area in the Netherlands. The study population was a sub-sample of a longitudinal field study on chronic non-specific lung diseases which was started in 1965. Pulmonary function tests were performed at three-yearly intervals. NO2 was measured for one week in the winter in kitchen, living room and bedroom of each home. Cross-sectional analyses showed negative associations between NO2 exposure and several pulmonary function parameters as measured in the 1982 study. No significant association could be found between NO2 exposure and pulmonary function decline since the start of the study.

Adult↗
PubMed1985

Indoor air pollution and its effect on pulmonary function of adult non-smoking women: III. Passive smoking and pulmonary function.

The association between pulmonary function and exposure to tobacco smoke in the home was investigated in a sample of adult, non-smoking women living in a rural area. The women were all participants in a large longitudinal survey on the natural history and determinants of chronic non-specific lung disease. On cross-sectional analysis, several pulmonary function parameters were found to be significantly associated with exposure to tobacco smoke in the home. There was no association between exposure and pulmonary function decline.

Adult↗
PubMed1985

Copia is transcriptionally responsive to environmental stress.

Adult Drosophila subjected to a variety of environmental stresses that induce classic Drosophila heat shock response simultaneously exhibit a rapid and significant rise in copia homologous transcripts. Levels of Drosophila Adh (alcohol dehydrogenase gene) and 18s ribosomal RNA were unaffected by environmental stress. Copia's ability to be induced by stress is correlated with the presence of sequences homologous to the heat shock promoter consensus sequence which appear to be appropriately positioned within the element's long terminal repeat (LTR). Although the copia-like element 297 also contains homologous sequences within its LTR, they are atypically positioned relative to the element's transcription start site and are non-functional in that the 297 element was not stress inducible. Hence, the position of the consensus sequence relative to a gene's transcription start site may be a factor in stress inducibility.

Acclimatization↗
PubMed2002

Microsatellite analysis of Drosophila melanogaster populations along a microclimatic contrast at lower Nahel Oren canyon, Mount Carmel, Israel.

Drosophila melanogaster populations collected at the south-facing slope (SFS) and north-facing slope (NFS) of lower Nahel Oren canyon, Mount Carmel, Israel display significant differences in survival and longevity at temperature, drought, and starvation stresses. Furthermore, significant assortative mating was previously observed between populations of the two slopes. We used a set of 48 microsatellite markers to analyze patterns of genetic differentiation between D. melanogaster populations from both slopes and D. simulans. Consistent with previous reports, we found D. simulans to be well differentiated from D. melanogaster. Genetic differentiation between SFS and NFS D. melanogaster populations was low (F(ST) = 0.0012). Also a tree of individuals based on the proportion of shared alleles and a model-based clustering method provided no evidence for population substructuring.

Animals↗
PubMed1997

Market turkey performance, air quality, and energy consumption affected by partial slotted flooring.

Two experiments were conducted with 600 male Large White turkeys to examine performance and health when reared from 5 to 18 wk of age on litter (L) partially slotted flooring (SF), and under two ventilation rates-control and reduced ventilation (80% control). In both experiments, body weights were improved significantly (P < 0.05) for turkeys reared on SF compared to L by 11 and 16% in Experiments 1 and 2, respectively. In comparison to L, SF significantly decreased incidence of leg problems in Experiment 1, whereas the incidence of breast blisters and buttons were increased in Experiment 2. Ammonia levels were reduced with SF, whereas dust levels were increased. Ventilation rate did not affect turkey performance. Ammonia and carbon dioxide levels were increased with reduced ventilation in Experiment 1. Dust levels were not affected by ventilation rate. Supplemental energy use was decreased in the SF system or by reducing the ventilation rate. In comparison to the control ventilation/litter treatment, the greatest decrease in energy use was observed with SF at 80% ventilation rates. Results indicate that the use of SF in a cold climate can improve body weight and substantially reduce energy use when excessive litter moisture is a problem. However, a greater incidence of blisters will limit application of SF due to lowered carcass quality and value.

Air↗
PubMed1998

Effect of litter moisture and brooding temperature on body weights of turkey poults experiencing poult enteritis and mortality syndrome.

Studies were conducted to determine the influence of the interactions among litter moisture (high [HiM]> or =40% vs low [LoM]< or =20%), brooding temperature (high [HiB] = 38 C vs normal [NrB] = 34 C), and development of poult enteritis and mortality syndrome (PEMS) as indicated by body weights, relative weights of lymphoid organs, and mortality in Control [C] vs Infected [I] groups. There was a significant interaction between litter moisture and brooding temperature that had a significant influence on BW. The brooding temperature main effect was not significant, but there was a significant litter moisture effect on BW. Body weights were suppressed by PEMS infection, but infected poults brooded at HiB on LoM had significantly greater BW than those brooded at NrB and HiB on HiM. Main effects showed that there were significant litter moisture- and brooding temperature-mediated responses for BW. Relative weights of lymphoid organs revealed significant disease main effects but no effect due to brooding temperature and litter moisture. There was a significant effect of disease and brooding temperature with regard to mortality. The results from this study suggest that litter moisture influences productivity and mortality associated with PEMS, but brooding temperature has the greatest influence on PEMS-associated mortality. Therefore, higher brooding temperature for turkey poults being placed into a facility where they may be at risk for PEMS exposure is recommended.

Animals↗
PubMed2000

Characterization of the contribution of water activity and moisture content to the population distribution of Salmonella spp. in commercial poultry houses.

Because Salmonella spp. can be spread from the production environment to the consumer, strategies are required to control Salmonella. One such intervention involves control of the distribution of the organism in poultry litter. In this regard, we have attempted to determine whether Salmonella spp. are uniformly distributed throughout the litter of commercial poultry houses, or if they are unevenly localized to "hot spots" associated with high surface litter water activity (Aw) and high total moisture levels. Of the 86 houses sampled, 48 (55.8%) were positive for Salmonella spp. using a combination of the drag swab and targeted litter culturing methods. Data are presented that show that elevated Aw and percentage moisture content values representative of targeted litter samples or whole-house moisture status are not statistically predictive of Salmonella contamination, using either drag swab or targeted litter culture results as indicators of contamination. This study suggests that favorable environmental conditions for the growth of Salmonella are unequally dispersed in poultry houses. Because there is not equivalent distribution of salmonellae in the surface litter, the drag swab technique is apparently necessary to adequately survey for Salmonella spp. contamination. The findings further suggest that the development of a methodology to detect areas within houses that possess risk factors favorable for Salmonella growth must also include elevated Aw and percentage moisture content levels. This capability may enable a grower to detect and intervene in these targeted areas with neutralizing procedures, agents, or other substances to provide significant reduction of Salmonella or other poultry-associated food-borne pathogens.

Animals↗
PubMed2000

Effects of atmospheric ammonia on albumen height and pH of fresh broiler breeder eggs.

Two experiments were conducted to study the stimulatory effect of atmospheric ammonia on albumen liquefaction. Albumen height and pH were measured in fresh eggs after 1 h of exposure to 0, 142, 294, 592, 2,747, or 6,052 mg/kg ammonia vapor. In Experiment 1, eggs exposed to ammonia concentrations of 2,747 and 6,052 mg/kg exhibited a significantly reduced albumen height compared with all other treatments. The 2,747 and 6,052 mg/kg treatments produced a significantly higher albumen pH compared with the 0, 142, and 294 mg/kg ammonia treatments. In Experiment 2, eggs exposed to ammonia concentrations of 2,747 and 6,052 mg/kg had a significantly reduced albumen height compared with eggs exposed to ammonia concentrations of 0, 142, and 592 mg/kg. Albumen pH was significantly higher at the 2,747 and 6,052 mg/kg concentrations of ammonia compared with the control. The linear regression for the effects of ammonia on albumen height and pH were highly significant in both experiments. The effect on yolk pH was inconsistent. The results suggest that the presence of atmospheric ammonia contributes to albumen liquefaction.

Ammonia↗
PubMed2000

Effects of ambient temperature, arginine-to-lysine ratio, and electrolyte balance on performance, carcass, and blood parameters in commercial male turkeys.

The effects of ambient temperature (T; 15 C vs. 30 C from 6 wk of age onwards), dietary Arg:Lys ratio (Arg:Lys ratio; 1.00 vs. 1.25), dietary electrolyte balance (DEB: 164 vs. 254 meq/kg), and their interactions on growth performance and carcass yields of male turkeys were studied. The experiment was designed as a split plot, including T x DEB as the main plot and Arg:Lys ratio as the sub-plot, with 24 pens containing 35 male turkeys each. Feed consumption, BW gain, mortality, and processing yields were measured. Temperature had a clear effect on performance during all age periods. Feed intake was significantly lower for the high T group compared with the low T group (322.7 vs. 432.3 g/bird per day; P < 0.001). Consequently, BW gain during the experimental period (28 to 140 d of age) was significantly lower for the high T group compared with the low T group (14.54 vs. 18.74 kg; P < 0.001). Feed:gain during the period of 28 to 140 d of age was significantly lower for the high T group compared with the low T group (2.51 vs. 2.61; P < 0.001). The high dietary Arg:Lys ratio increased feed intake significantly until 56 d of age (200.6 vs. 197.6; P < or = 0.034). A high Arg:Lys ratio resulted in significantly higher BW gain until 98 d of age (10.03 vs. 9.84 kg; P < or = 0.024). The Arg:Lys ratio did not affect feed:gain throughout the experiment. Dietary electrolyte balance did not affect performance parameters. No consistent two- or three-way interactions were observed. Processing yields were only affected significantly by T, and not by Arg:Lys ratio or DEB main effects. High T resulted in lower cold carcass (73.2 vs. 74.9%) and breast meat yields (33.5 vs. 36.0%), and higher thigh (18.9 vs. 18.1%), drumstick (14.5 vs. 13.2%), and wing yields (11.7 vs. 10.6%) compared with low T. We concluded that growth performance is compromised by higher T, and altering the Arg:Lys ratio or DEB does not alleviate this impaired performance. Dietary Arg levels seem to be important when dietary Lys is marginal relative to the requirement.

Animal Feed↗
PubMed2005

Photosynthetic acclimation to dynamic changes in environmental conditions associated with deciduous overstory phenology in Daphniphyllum humile, an evergreen understory shrub.

Photoprotective responses during photosynthetic acclimation in Daphniphyllum humile Maxim, an evergreen understory shrub that grows in temperate deciduous forests, were examined in relation to changes in light availability and temperature caused by the seasonal dynamics of canopy leaf phenology. Gradual increases in irradiance in the understory from summer to autumn as overstory foliage senesced were accompanied by increased concentrations of xanthophyll cycle pigments (VAZ) in understory leaves. The chlorophyll (Chl) a/b ratio in understory leaves also increased from summer to autumn, reflecting the change in ratio of the light-harvesting antenna to the reaction center. However, low temperatures following overstory leaf fall reduced Rubisco activity. In contrast, the photosynthetic capactiy of leaves of D. humile growing at the forest border, which was higher in summer than that of leaves of understory plants, decreased in autumn. In autumn, Fv/Fm ratios decreased and concentrations of zeaxanthin (Z) and especially antheraxanthin (A) increased in leaves of both forest-border and understory plants. Although VAZ was twice as high in leaves of forest-border than of understory plants, NPQ was similar in both. We conclude that leaves of understory plants are able to acclimate to seasonal changes in light and temperature by varying their photosynthetic and photoprotective functions, thereby taking advantage of the favorable light conditions caused by overstory leaf fall.

Acclimatization↗
PubMed2005

Influences of environmental factors on the radial profile of sap flux density in Fagus crenata growing at different elevations in the Naeba Mountains, Japan.

Sap flux density was measured continuously during the 1999 and 2000 growing seasons by the heat dissipation method in natural Fagus crenata Blume (Japanese beech) forests growing between 550 and 1600 m on the northern slope of the Kagura Peak of the Naeba Mountains, Japan. Sap flux density decreased radially toward the inner xylem and the decrease was best expressed in relation to the number of annual rings from the cambium, or in relation to the relative depth between the cambium and the trunk center, rather than as a function of absolute depth. The relative influences of radiation, vapor pressure deficit and soil water on sap flux density during the growing season were similar for the outer and inner xylem, and at all sites. Measurements of soil water content and water potential at a depth of 0.25 m demonstrated that sap flux density responded similarly and sensitively to water potential changes in this soil layer, despite large differences in rooting depth at different elevations, localizing one important control point in the functioning of this forest ecosystem. Identification of the relative influences of radiation, vapor pressure deficit and drying of the upper soil layer on sap flux density provides a framework for in-depth analysis of the control of transpiration in Japanese beech forests. In addition, the finding that the same general controls are operating on sap flux density despite climate gradients and large differences in overall forest stand structure will enhance understanding of water use by forests along elevation gradients.

Altitude↗
PubMed2006

A mathematical model linking tree sap flow dynamics to daily stem diameter fluctuations and radial stem growth.

To date, models for simulating sap flow dynamics in individual trees with a direct link to stem diameter variation include only the diameter fluctuation driven by a change in stem water storage. This paper reports results obtained with a comprehensive flow and storage model using whole-tree leaf transpiration as the only input variable. The model includes radial stem growth based on Lockhart's equation for irreversible cell expansion. It was demonstrated that including growth is essential to obtaining good simulation results. To model sap flow dynamics, capacitance of storage tissues was assumed either constant (i.e., electrical analogue approach) or variable and dependent on the water content of the respective storage tissue (i.e., hydraulic system approach). These approaches resulted in different shapes for the desorption curve used to calculate the capacitance of storage tissues. Comparison of these methods allowed detection of specific differences in model simulation of sap flow at the stem base (F(stem)) and stem diameter variation (D). Sensitivity analysis was performed to select a limited subset of identifiable parameters driving most of the variability in model predictions of F(stem) and D Both the electrical analogue and the hydraulic system approach for the flow and storage model were successfully calibrated and validated for the case of a young beech tree (Fagus sylvatica L.). Use of an objective model selection criterion revealed that the flow and storage model based on the electrical analogue approach yielded better predictions.

Calibration↗
PubMed1993

How does environmental enrichment aid performance following cortical injury in the rat?

Understanding how postoperative environmental brain damage in animals may help in devising treatment regimes for brain injured humans. This study tests Finger's hypothesis that EC increases the animal's ability to switch to alternative cues when brain damage renders the cues normally used in performing the task less salient or unavailable. Following preoperative water maze training to visual cues, rats were given either bilateral occipital lesions or sham operations, housed in either EC or standard conditions and then tested in the water maze in alternating visual and non-visual cue conditions. We found no evidence that postoperative EC helped lesioned rats to switch to non-visual cues when visual cues were unavailable.

Acclimatization↗
PubMed1983

Performance characteristics of two double-walled infant incubators.

Two double-walled incubators, the Air Shields C-100 and the Ohio IC, were evaluated for performance characteristics. The Ohio incubator heated more rapidly from room temperature to 36 degrees C, but overshot the preset air temperature and produced greater fluctuation in air temperature due to the operation of the servocontrol system at equilibrium. Neither incubator produced excessive air currents, sound levels, or carbon dioxide accumulation.

Air Movements↗
PubMed1983

Indoor radiation exposures from 222Rn and its daughters: a view of the issue.

Exposure to 222Rn daughters indoors can result in significant risk to the general public, particularly those living in homes with much higher than average concentrations. This paper reviews what is known about indoor concentrations, associated risks and the effect of measures to save energy by reducing ventilation rates, using U.S. housing as an example. It concludes that, by employing appropriate control measures in homes having unacceptably high concentrations, the average exposure (and therefore risk) of the general public can remain at its present level, or even decrease, despite programs to save energy by tightening homes.

Air Pollutants, Radioactive↗
PubMed1983

Background atmospheric 222Rn concentrations outdoors and indoors: a review.

The sources of outdoor and indoor atmospheric radon are examined. The variation of outdoor atmospheric radon with time of day, time of year, altitude and geographic location is quantitatively assessed. Average values of outdoor atmospheric radon concentrations are examined and it is estimated that the mean value for normal areas of the contiguous United States lies in the range of 100-400 pCi/m3 and is probably about 250 pCi/m3. Values for Alaska and Hawaii are an order of magnitude lower. Indoor atmospheric radon concentrations are found to vary with time of day, geographic location and story above ground.

Altitude↗