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B T Johnson

Publications and source records attributed to B T Johnson.

30 records · Page 2Linked to original sources
PubMed1996

Elevated blood pressure and personality: a meta-analytic review.

A meta-analysis of 295 relevant effect sizes obtained from 25,469 participants confirmed expectations that elevated blood pressure (BP) and essential hypertension (EH) would be associated with lower affect expression but with more negative affectivity and defensiveness. The strongest associations occurred for defensiveness and measures of anger and affect expression linked to an interpersonal context(s). However, a number of other factors also were found to moderate associations of BP with personality measures, including awareness of BP status, gender, occupation, and diastolic versus systolic BP assessment. Given these moderators, the authors conclude that a traditional view of personality causing EH is untenable and that, not incorporating multifactorial, synergistic approaches is likely to obscure associations of personality-behavior with EH.

Adult↗
PubMed1989

A multiple testing approach for hazard evaluation of complex mixtures in the aquatic environment: the use of diesel oil as a model.

Traditional single species toxicity tests and multiple component laboratory-scaled microcosm assays were combined to assess the toxicological hazard of diesel oil, a model complex mixture, to a model aquatic environment. The immediate impact of diesel oil dosed on a freshwater community was studied in a model pond microcosm over 14 days: a 7-day dosage and a 7-day recovery period. A multicomponent laboratory microcosm was designed to monitor the biological effects of diesel oil (1.0 mg litre(-1)) on four components: water, sediment (soil + microbiota), plants (aquatic macrophytes and algae), and animals (zooplanktonic and zoobenthic invertebrates). To determine the sensitivity of each part of the community to diesel oil contamination and how this model community recovered when the oil dissipated, limnological, toxicological, and microbiological variables were considered. Our model revealed these significant occurrences during the spill period: first, a community production and respiration perturbation, characterized in the water column by a decrease in dissolved oxygen and redox potential and a concomitant increase in alkalinity and conductivity; second, marked changes in microbiota of sediments that included bacterial heterotrophic dominance and a high heterotrophic index (0.6), increased bacterial productivity, and the marked increases in numbers of saprophytic bacteria (10 x) and bacterial oil degraders (1000 x); and third, column water acutely toxic (100% mortality) to two model taxa: Selenastrum capricornutum and Daphnia magna. Following the simulated clean-up procedure to remove the oil slick, the recovery period of this freshwater microcosm was characterized by a return to control values. This experimental design emphasized monitoring toxicological responses in aquatic microcosm; hence, we proposed the term 'toxicosm' to describe this approach to aquatic toxicological hazard evaluation. The toxicosm as a valuable toxicological tool for screening aquatic contaminants was demonstrated using diesel oil as a model complex mixture.

Journal Article↗
PubMed1988

Attitudes toward older and younger adults: a meta-analysis.

Attitudes toward the elderly have been examined in a number of empirical studies, yet the question of whether the elderly are viewed more negatively than younger persons has not been resolved. A meta-analysis of the literature was conducted to examine this question; results demonstrated that attitudes toward the elderly are more negative than attitudes toward younger people. However, smaller differences between the evaluations of elderly and younger targets were found when (a) the study used measures of personality traits (compared with measures of competence), (b) there were a larger number of dependent measures included in the effect size, (c) specific information was provided about the target person (compared with when a general target such as old person was used), and (d) a between-subjects design (compared with a within-subjects design) was used. These results support Lutsky's (1981) conclusion that age, in and of itself, seems to be less important in determining attitudes toward the elderly than other types of information. The methodological limitations within the literature and a need to consider multiple components of attitudes toward older individuals are discussed.

Adult↗
PubMed1984

Impact of an oil field effluent on microbial activities in a Wyoming river.

The survival, functions, and physiological diversity of autochthonous sediment microbiota were examined in situ at five stations along the Little Popo Agie River, WY; one station above, one at, and three below a discharge point for oil wastewater from Union Oil Company's Dallas Field. Below the oil wastewater discharge point there were increases in electron-transport activity, carbon dioxide production, and microbial populations of heterotrophs, ammonifiers, hexadecane degraders, starch hydrolyzers, protein hydrolyzers, and sulfate reducers. At a station 1420 m below the discharge point, however, overall sediment microbial activities and all of the physiological groups of bacteria, except hexadecane-degrading microbiota, were at levels comparable with those at the control station above the discharge point. Similarly, mineralization of glucose, amino acids, hexanoic acid, and hexadecane was elevated at stations directly below the discharge point, but appeared to subside rapidly. Xenobiotic biodegradation potential of the sediments varied with the chemical and the sample location and was not directly related to oil residue levels in the sediment. Microorganisms thus appeared to maintain physiological diversity and increased in numbers and activity in a riverine environment that contained petroleum hydrocarbon concentrations known to be deleterious to freshwater fish and macrobenthic communities.

Alkanes↗
PubMed1981

Biological effects of kepone and mirex in freshwater invertebrates.

Acute and chronic toxicity studies of Kepone (chlordecone) and mirex were conducted with daphnids (Daphnia magna), amphipods (Gammarus pseudolimnaeus), and larvae of a midge (Chironomus plumosus). Acute toxicities of Kepone ranged from a 48-hr EC50 of 350 microgram/L for midges to a 96-hr LC50 of 180 microgram/L for amphipods, whereas the acute toxicities of mirex to all three taxa exceeded 1000 microgram/L. Maximum acceptable toxicant concentrations (MATC's) for Kepone and mirex were estimated by measuring reproduction of daphnids, growth of amphipods, emergence of midges, and survival of all organisms. MATC for Kepone was estimated to be between 9 and 18 microgram/L for daphnids, between 1 and 2 microgram/L for amphipods, and between 8.4 and 18 microgram/L for midges; MATC for mirex exceeded 34 microgram/L for daphnids and midges, but less than 2.4 microgram/L for amphipods. The concentration of Kepone and mirex accumulated by daphnids was 760 and 8025 times, respectively, the concentration in water. Estimated times for elimination of 50% of the residues by daphnids were 141 hr for Kepone and 12 hr for mirex.

Animals↗
PubMed1973

Biomagnification of p, p'-DDT and methoxychlor by bacteria.

Aerobacter aerogenes and Bacillus subtilis accumulated p, p'-DDT and methoxychlor directly from water. Uptake of both (14)C-labeled organochlorine insecticides was rapid; 80 to 90% of the 24-h residues were reached within 30 min. Total cellular residues varied linearly with concentrations of DDT and methoxychlor in water ranging from 0.5 to 5.0 mug/liter. The residue magnification factors from water were between 1,400- to 4,300-fold, but were independent of insecticide concentrations in water. When the insecticide-exposed microbial cells were washed with pesticide-free water, DDT residues were 45% in A. aerogenes and 30% in B. subtilis, whereas the methoxychlor level decreased nearly 75% in both organisms. Subsequent washing did not further reduce the insecticide residue. Autoclave-killed bacteria also rapidly adsorbed DDT and methoxychlor from water and, in some instances, residues were higher than in the living cells. Molecular polarity and lipid solubility appear to influence the retention of the organochlorine insecticides by bacterial cells.

Autoradiography↗
PubMed1967

Conversion of DDT to DDD by pathogenic and saprophytic bacteria associated with plants.

Of 27 microorganisms examined, 23 plant pathogenic and saprophytic bacterial species were found to convert p,p' DDT to p,p' DDD under anaerobic conditions. The range of conversion of DDT (10 micrograms per milliliter) during an incubation of 14 days was from a trace to over 5 micrograms per milliliter, with the majority of the bacteria showing the greatest activity during the final 7-day period. There is evidence that metabolites of DDT other than DDD are also produced.

Alcaligenes↗
PubMedDate not supplied

Enhancing early discharge with home follow-up: a pilot project.

Although early hospital discharge of mothers and infants reduces health care costs, it also decreases the opportunities for women to learn the mothering role with the help of health care providers. This article describes the development of a program in which hospital staff nurses provide follow-up care to new mothers and their infants in the home. In addition, it compares the nonroutine health care expenditures in the postpartum period of mother-infant dyads receiving this service and of dyads who did not.

Adolescent↗