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Biomedical subjects

J E Gibson

Publications and source records attributed to J E Gibson.

At least 19 recordsLinked to original sources
PubMed1992

Effects of duration and timing of environmental enrichment on voluntary ethanol intake in rats.

The effects of exposure to five environmental rearing conditions on subsequent voluntary ethanol intake was examined. Male weanling rats were reared for 60 days in either an enriched environment, individually, or in a smaller enriched environment (quasienriched). The quasienriched environment was employed to allow for a group measurement of ethanol intake. Following the initial 60-day environmental exposure period, the three initial groups (Enriched, Isolation, Quasienriched) were randomly subdivided into five groups (Enriched/Isolation, Isolation, Isolation/Quasienriched, Quasienriched, Quasienriched/Isolation) and exposed to increasing concentrations of ethanol (3-9% v/v) in a free choice with water. Results indicated that exposure to an enriched environment for 60 days does not alter ethanol intake. In contrast, rats exposed to the quasienriched environment while having access to ethanol demonstrated a significant increase in voluntary ethanol intake as compared to all other groups. Exposure to different environmental conditions while having access to ethanol was not by itself sufficient to alter ethanol intake. These data are discussed in terms of the amount and timing of exposure to an enriched environment necessary to alter voluntary ethanol intake.

Animals↗
PubMed1989

Effects of environmental enrichment on voluntary ethanol intake in rats.

The effects of exposure to four environmental rearing conditions on subsequent voluntary ethanol intake were examined. Male weanling rats were were reared in either an enriched environment or individually for 90 days. After the 90-day environmental exposure period, the initial groups (Enriched and Isolated) were randomly subdivided into four groups (Enriched, Enriched/Isolated, Isolated, and Isolated/Enriched) and exposed to increasing concentrations of ethanol (3% to 9% v/v) in a free choice with water. Therefore, half the animals raised in the enriched environment were permanently placed into individual cages (Enriched/Isolated) for the remainder of the study. Likewise, half of the animals previously reared individually were exposed daily (0900-1700) to the enriched environment (Isolated/Enriched). Results indicated that the enriched animals consumed greater amounts of ethanol as compared to all other groups. In contrast, rats placed in isolation following 90 days of enrichment demonstrated significant reductions in voluntary ethanol intake. The data suggest that rearing in an enriched environment for 90 days and continued exposure following 111 days of age, are necessary to enhance voluntary ethanol consumption.

Alcohol Drinking↗
PubMed1989

The effectiveness of an AIDS education campaign on a college campus.

This paper reports on an AIDS education campaign at a California college campus. A pretest-posttest design was used to determine whether the AIDS-related attitudes of students, faculty, and staff were affected by an AIDS Awareness Week. The results showed that the awareness week was successful in exposing the campus community to AIDS information. It was only marginally effective in changing AIDS-related attitudes because pretest attitudes were already at desirable levels, only a fraction of the campus community attended the highly motivating events of the campaign, and faculty did not actively support the goals of the campaign.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Preparing for the twenty-first century: report of the TOX-90's Commission. Planning Committee.

A clear consensus developed that toxicology will be driven by advances in related fields. New technology and knowledge developed by all relevant disciplines, therefore, must be integrated into toxicology; progress in toxicology demands that the discipline must increasingly address good science and the scientific method. Issues of critical importance to the field, such as risk estimation of the health effects of chemical and physical agents and the education of toxicologists, can only be addressed by meeting these objectives.

Toxicology↗
PubMed1988

Opportunities for improving techniques for interspecies extrapolation in the risk assessment process.

Quantitative estimates of human carcinogenic risk from chemical exposure are currently derived primarily from linearized multistage model analyses of the tumor response as observed in chronic laboratory animal bioassays versus administered dose. The numerous ad hoc assumptions that provide a rationale for this generic approach to carcinogenic risk assessment can only be evaluated critically when mechanistic data directly relevant to the low-dose and interspecies extrapolation problems are available. Clear needs exist to develop such ancillary data bases and the means for explicitly incorporating them into the risk estimation process. Target site dosimetry provides one useful organizing concept. Physiological response modeling can account systematically for interspecies variations in the distribution and disposition of chemicals in relation to external measures of exposure. Direct measurements of interactions of chemicals and their metabolites with specific target macromolecules can provide sensitive and biologically meaningful exposure indices. Alternatively, quantitation of toxic effects such as altered cell regulation and differentiation can serve the same purpose. Virus and oncogene activation, DNA damage and repair, and enhanced cell proliferation provide additional biological markers of exposure. They may also comprise critical elements of the carcinogenic process. Identification of the actual mechanisms involved should eventually lead to the development of risk assessment models that adequately reflect the unique biological and toxicological characteristics of different species-chemical combinations.

Animals↗
PubMed1979

Effect of polybrominated biphenyls on the development of hepatic excretory function.

Polybrominated biphenyls (PBBs) stimulate hepatic drug metabolism in adult and developing rats. The purpose of this investigation was to determine the influence of PBBs on the development of the liver as an organ for chemical excretion. Exposure of developing rats to polybrominated biphenyls (PBBs) by feeding 50 ppm of PBBs to pregnant or lactating mothers and rat weanlings did not produce overt toxicity when compared to controls over a 49-day postnatal period. However, prenatal and postnatal dietary exposure to PBBs resulted in elevated liver weight. In 15-day-old rats, increased liver weight after PBBs was correlated with enhanced ouabain transport from plasma into bile. Liver weight was also elevated in 21-, 35- and 49-day-old rats treated with PBBs, but this effect was not associated with stimulation of ouabain transport in these animals. Stimulation of ouabain transport after PBBs in 15-day-old rats was associated with increased hepatic uptake of ouabain. Stimulation in 15-day-old rats and not older rats may be attributed to the relative importance of uptake for ouabain transport in 15-day-old rats.

Aging↗
PubMed1979

Characteristics of hepatic excretory function during development.

The purpose of this investigation was to characterize the development of hepatic excretory function in rats. Cumulative (40 min) intestinal ouabain content was lower and plasma ouabain concentrations were higher in 15-day-old rats than in 21-, 25-, 35- and 45-day-old animals and reached adult levels when rats were 35 days old. Impaired transport of ouabain in rat neonates correlated to low initial ouabain concentration in liver, which suggested that the inability of young rats to accumulate ouabain in liver may be the most important determinant for functional insufficiency. Bile duct ligation and bile salt infusion, treatments that primarily depress and enhance (respectively) excretion of sulfobromophthalein from liver into bile, markedly altered the disappearance of sulfobromophthalein from plasma of adult rats but did not appreciably affect sulfobromophthalein disappearance from blood of 15-day-old rats. The effect of bile duct ligation on ouabain transport in 15-day-old rats was also not as dramatic as the effect produced in adult rats. Hepatic uptake is rapid in adult rats and overall excretion is limited by a slower rate of transport from liver into bile. The lower rate of uptake in 15-day-old rats may limit overall transport function in young animals.

Aging↗
PubMed1978

The impact of a new geriatric program in a hospital for the chronically ill.

Reports of the rapidly increasing proportion of persons aged 65 years and more in Canada and the resultant need for changes in the country's health care system prompted experimental changes in the operation and training procedures at St. Mary's of the Lake Hospital, Kingston, Ont. Aimed at better patient care and at better education of medical house staff in geriatrics and long-term care, the revised program is permeated with the philosophy of rehabilitation. It includes full-time staff, a geriatric outpatient clinic, a day hospital, a team approach to patient care (with regular team audits), problem-oriented medical records, a formal physical medicine section with a district inpatient unit, and an intensive inservice education program. After the first year of the program patient outcome had improved and more efficient use was being made of continuing care beds because of larger numbers of patinets being discharged home after shorter stays. This may be one avenue for deceleration of our country's dismal rate of institutionalization.

Aged↗
PubMed1978

Effect of polybrominated biphenyls on hepatic excretory function in rats and mice.

The purpose of this investigation was to determine the influence of polybrominated biphenyls (PBBs) on hepatic excretory function in developing and adult rats and mice. Prenatal or postnatal dietary exposure to PBBs (50 ppm in diet of pregnant or lactating mother or in diet of rat weanlings) resulted in elevated liver weight in developing rats. In 15-day-old rats that had been treated with PBBs increased liver weight correlated to enhanced ouabain transport from plasma into bile. Liver weight was also elevated in 21, 35, and 49-day-old rats exposed to PBBs, but this effect was not associated with stimulation of ouabain transport in these animals. However, adult rats fed 100 ppm PBBs for two weeks had significantly lower plasma concentrations of sulfobromophthalein (BSP) and increased biliary excretion of BSP, when compared to controls. PBBs-fed adult rats also excreted a greater percentage conjugated BSP (BSP-GSH) into bile. Two week dietary treatment of 100, 150, and 200 ppm PBBs resulted in enhanced initial disappearance of indocyanine green (ICG) from plasma of adult mice. However, dietary doses of 100 and 200 ppm PBBs to adult mice was not associated with enhanced capacity for ouabain excretion. In contrast, treatment with PBBs through the mother's diet (50 ppm) resulted in an almost twofold increase in cumulative ouabain excretion in 15-day-old mice. The results suggest that PBBs stimulate hepatic drug elimination in rats and mice, but the magnitude of the effect is dependent on age and transported compound.

Age Factors↗
PubMed1978

Distribution of polybrominated biphenyls after dietary exposure in pregnant and lactating rats and their offspring.

Female rats were fed PBBs in the diet (50 ppm) from day 8 of gestation to day 21 of gestation, from day 1 postpartum to day 14 postpartum or from day 8 of gestation through day 14 postpartum. Levels of PBBs were measured in various tissues. Small concentrations of PBBs (less than 5 microgram/g) were found in the brain, heart, lung, liver, small intestine, placenta, and gravid uterus. Larger concentrations (less than 30 microgram/g) were found in kidneys, the nongravid uterus, skin, mammary tissue, and fat. Lactation did not significantly alter the concentrations of PBBs found in tissues other than mammary tissue. Offspring were subjected to several exposure regimens by cross-fostering. Concentrations of PBBs in the neonatal livers were higher than in the adults nursing them. Transfer of PBBs via the milk appears to be much more important to appearance of PBBs in newborns than does placental transfer.

Animal Feed↗