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Results for “Modifiable factors”

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At least 199 records · Page 11Linked to original sources
PubMed2005

[Individualized health behavior? Social structures, peer influences and life style as modifying factors of nutritional behavior of adolescents].

OBJECTIVE: Health behaviours are often explained as being determined by health knowledge, occupation, education and income. Yet, in increasingly individualized societies individuals are brought to develop personal strategies of orientation and behaviours, the later being detached from traditional status or class membership. The present study (secondary analysis) explores to what extent health behaviours are more or less individualized or still linked to social living conditions. METHODS: Eating behaviours and social status are based on a 2001 questionnaire survey among 393 randomly selected adolescents from the city of Leipzig, Germany. RESULTS: The findings show a distinct social patterning of eating behaviours. Those patterns can be explained as part of adolescents' lifestyles. Findings also indicate that the patterns of eating behaviours are strongly linked to the social background of those adolescents. CONCLUSIONS: It is concluded that for adolescents raised in deprived social conditions it is more difficult to develop health preferences conducive for health promoting behaviours.

Adolescent↗
PubMed1998

Biotic factors modifying acute toxicity of aqueous cadmium to estuarine amphipod Leptocheirus plumulosus.

A 96-h exposure to aqueous cadmium (Cd) is the recommended reference toxicity test for 10-day sediment bioassays with the estuarine amphipod, Leptocheirus plumulosus (US EPA 1994). This water-only test was used to assess the influence of organism size, sex, and nutritional status on the sensitivity of laboratory-cultured L. plumulosus to Cd. In addition, the response of field-collected amphipods was compared to similarly sized laboratory animals to assess potential seasonal changes in Cd sensitivity. Lipid content of test organisms was measured in these seasonal experiments and those evaluating effects of nutritional status because of its potential as an indicator of physiological condition. LC50 values of laboratory animals size-sorted on nested 500-, 710-, and 1000-micron mesh sieves, increased with size class: 0.36, 0.65, and 0.88 mg Cd/L, respectively. Gravid females were less sensitive than males or mature females to aqueous Cd. Studies on the influence of the molt cycle on Cd toxicity indicated enhanced sensitivity of immediate postmolt animals that may explain some of the observed differences in Cd tolerance. Nutritional effects were investigated by comparing the sensitivity of fed and starved laboratory-reared amphipods. Starved juveniles and adults were significantly smaller than their fed counterparts and exhibited a 28-43% reduction in lipid content, respectively. However, comparison of LC50 values indicated no significant differences in sensitivity to Cd between starved and fed juveniles (0.23 vs 0.30 mg Cd/L) or adults (0.37 vs 0.52 mg Cd/L). Field-collected amphipods were typically more sensitive to Cd than laboratory animals, regardless of the season, although their lipid content varied, ranging from 6.6% in August to 13.7% in November. Results are discussed with respect to the use and interpretation of toxicity tests with this species.

Animals↗
PubMed1998

Nickel uptake by Pseudomonas aeruginosa: role of modifying factors.

Pseudomonas aeruginosa cells growing in minimal medium were 40-fold more sensitive to Ni2+ than cells growing in enriched medium, suggesting a possible protective role of medium ingredients. Likewise, cells pre-grown in enriched medium showed a high Km (6.15 mM) and increased Ni2+ uptake (950 nmol mg-1 protein, 1h) over cells pre-sown in minimal medium (Km, 0.48 mM; 146 nmol mg-1 protein, 1 h). The overall pattern indicates that cells pre-grown in enriched medium were characterized by having lowered affinity towards Ni2+ than those with minimal medium background. The enhanced Ni2+ uptake by enriched medium-grown cells can be correlated with the improved metabolic state of the cells. Ni2+ uptake was optimum at neutrality (pH 7.0). A major Ni2+ transport system was competitively inhibited by Mg2+, Zn2+, Cd2+, or Co2+ (400 microM each). Noticeably, a minor Ni2+ transport pathway was still operative even in the higher concentration range of Mg2+ (4 mM and 40 mM). The stimulation of Ni2+ uptake monitored in the presence of different carbon sources (0.5% wt/vol, each) showed the sequence: glucose (1.6-fold) > phenol = gallic acid (1.5-fold). Succinate, in comparison, reduced Ni2+ uptake (0.5-fold) possibly because of its acting as a metal chelator as well. Sensitivity of Ni2+ transport towards methyl viologen, azide, 2-4 DNP, and DCCD suggested that transport was energy-linked.

Cations, Divalent↗
PubMed1999

Energy-dependent Ca(2+) efflux from the cells of nostoc calcicola Breb: role of modifying factors

Energy-dependent Ca(2+) efflux and its regulation from the diazotrophic cyanobacterium Nostoc calcicola Breb has been investigated. Like Ca(2+) uptake, Ca(2+) efflux pattern also reflected a rapid phase for the first 10 min followed by a slower one lasting up to 1 h with a total of 80 nmol Ca(2+) mg(-1) protein (31% of the Ca(2+) concentration taken in by such cells at 1 h). Ca(2+) efflux kinetics remained hyperbolic with a K(m) of 1.9 mM and V(max) 5.5 nmol mg(-1) protein min(-1). Ca(2+) efflux to a major extent depended on photosynthetic energy generation as the cells facing dark incubation and addition of 3-(3, 4-dichlorophenyl)-1-dimethyl urea (DCMU) to light-grown cells showed significant reduction in Ca(2+) extrusion. The strong inhibition in Ca(2+) efflux by addition of metabolic inhibitors like carbonyl cyanide-p-nitrofluoromethoxylphenyl hydrazone (FCCP) and N,N, -dicyclohexylcarbo-diimide (DCCD) suggested the vital role of membrane potential and ATP hydrolysis in driving this process. Verapamil (Ca(2+) antagonist) had insignificant effect on Ca(2+) efflux, whereas the addition of Calmodulin antagonists like trifluoroperazine, W-7 and compound 48/80 resulted in the enhancement in Ca(2+) efflux over control sets, thus suggesting that this increase may be owing to the additional extrusion of intracellular free calcium that was unable to bind with calmodulin in the presence of these antagonists.http://link.springer-ny. com/link/service/journals/00284/bibs/39n5p254.html</HEA

Journal Article↗
PubMed1989

Variation and modifying factors of the exposure to lead and cadmium based on an epidemiological study.

Exposure to cadmium and lead was studied using a dietary survey. Data for 1348 individuals aged 25-64 years were collected using 3-day food records. In addition to the dietary intake of heavy metals, the effect of the following were also analyzed: smoking frequency, place of residence, occupation and age. Total cadmium and lead exposure was estimated by calculating intake from food plus that from inhalation, i.e. from urban air and smoking. Heavy smoking increased the cadmium exposure three-fold. The distribution curve of total cadmium exposure was bimodal due to the additional exposure caused by smoking. The distribution curve of the lead and cadmium exposure from food was also skewed, being mostly influenced by food intake. Contaminated urban air slightly increased the total exposure to lead. Occupation had a minor effect on the exposure to both metals. Housewives and retired persons were the least exposed groups. The distribution pattern and wide range of heavy metal exposure should be taken into account in risk assessment for contaminants in food. The additional exposure to cadmium and lead from smoking and from air and water should be considered.

Adult↗
PubMed1992

Preexposure temperature acclimation and diet as modifying factors for the tolerance of golden ide (Leuciscus idus melanotus) to short-term exposure to 4-chloroaniline.

The influence of different temperature and nutrition regimes on the acute toxicity of 4-chloroaniline to golden ide (Leuciscus idus melanotus) was investigated. Acute toxicity was determined over 48 hr at 20 degrees C without feeding after a 2-day acclimation period. In an attempt to reveal underlying mechanisms accounting for diet- and temperature-related differences in the toxicant resistance of golden ide, biochemical and quantitative morphological parameters of the liver, a central organ in the xenobiotic metabolism of fish, were recorded throughout the 12-week acclimation period. In cold-acclimated fish, acute toxicity of 4-chloroaniline was 40% higher than in fish acclimated to 20 degrees C. If compared to 20 degrees C, preacclimation to 14 degrees C was characterized by a lower specific growth rate, an increase of hepatic glycogen, and a decrease of body and liver lipid deposits. The organelle composition of hepatocytes was not significantly altered by temperature acclimation. For the nutrition experiment, commercially available diets A and B of similar crude composition were used. Acute toxicity of 4-chloroaniline was 60% lower with diet B than with diet A. If compared to diet B, diet A induced a higher specific growth rate and increased hepatocellular volume of endoplasmic reticulum and Golgi fields, whereas glycogen and lipid of the liver as well as body lipid contents were reduced. The toxicity of 4-chloroaniline was correlated with the development of the endoplasmic reticulum, the major site of biotransformation enzymes. A consistent correlation with lipid contents could not be established. Results illustrate not only that assay conditions during the actual test may profoundly interact with results of toxicity studies, but also that maintenance conditions before the test can have significant consequences on results. In order to improve reproducibility of the results of acute toxicity tests, more consideration should be given to the standardization of pretest maintenance conditions of fish.

Adaptation, Physiological↗
PubMed1992

Liver medium-term bioassay in rats for screening of carcinogens and modifying factors in hepatocarcinogenesis.

The present report describes a study of the hepatocarcinogenic potential of a second large assay series of 94 compounds carried out using the rapid bioassay system (DEN-PH model) developed in this laboratory and based on the two-step concept of hepatocarcinogenesis. Male F344 rats were initially given a single dose of diethylnitrosamine (DEN, 200 mg/kg body weight ip) and, starting 2 wk later, were treated with test compounds for 6 wk and then killed, all rats being subjected to a two-thirds partial hepatectomy at wk 3. Carcinogenic potential was scored by comparing the numbers (no./cm2) and areas (mm2/cm2) of induced glutathione S-transferase placental form (GST-P) positive foci in the livers of groups of about 15 rats with those of corresponding control groups given DEN alone. Positive was scored for a significant increase (P < 0.05) in quantitative values of GST-P positive foci, negative for no change or a decrease. Results for the 94 compounds were also compared with previously published data from Salmonella/microsome (Ames) tests and long-term carcinogenicity studies in rats and mice. Of the known liver carcinogens, 14 out of 14 (100%) mutagenic (Ames test) compounds and 10 out of 12 (83%) non-mutagenic compounds gave positive results in our DEN-PH system (mean 92%). Two hepatocarcinogenic peroxisome proliferators did not enhance the development of GST-P positive foci. Carcinogens other than hepatocarcinogens gave fewer positive results (five out of 17, 29%). One of the 13 compounds reported as non-carcinogenic, malathion, gave positive results in the DEN-PH assay, suggesting that this compound is a weak hepatocarcinogen or tumour promoter for hepatocarcinogenesis based on the two-stage hypothesis for carcinogenesis. The present study also provided information regarding the inhibitory potential of nine compounds. The practical usefulness and benefits of the DEN-PH protocol for the rapid screening of carcinogenic agents are discussed.

Animals↗
PubMed1980

Environmental temperature, a factor modifying the acute toxicity of organic solvents, heavy metals, and agricultural chemicals.

1500 male mice, previously acclimatized to 8,22 or 38 degrees C, were used to determine the median lethal doses of organic solvents, heavy metals and agricultural chemicals by the Up-and-Down method via several routes of administration. Acute toxicity of benzene, trichloroethylene, mercuric chloride, cadmium chloride, fratol, methylparathion and dieldrin increased markedly at a low temperature of 8 degrees C, as well as at a high temperature of 38 degrees C. Acute toxicity of toluene, copper sulfate and chromium trioxide was only enhanced at a high temperature of 38 degrees C.

Animals↗