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Biomedical subjects

D H Taylor

Publications and source records attributed to D H Taylor.

85 records · Page 5Linked to original sources
PubMedDate not supplied

Echinococcus granulosus: in vitro maintenance of whole cysts and the assessment of the effects of albendazole sulphoxide and praziquantel on the germinal layer.

Small entire cysts of Echinococcus granulosus of human and animal origin were cultured in vitro in the presence or absence of albendazole sulphoxide (1000 micrograms/litre) or praziquantel (500 micrograms/litre) for 10 or 11 d, and subsequently passaged into the peritoneal cavity of gerbils to assess viability by continued cyst growth. Viability was reduced in the presence of albendazole sulphoxide, and disintegration of the germinal layer immediately after culture was demonstrated at the ultrastructural level. Praziquantel had no apparent effect on cyst growth.

Albendazole↗
PubMedDate not supplied

Trichloroethylene affects learning and decreases myelin in the rat hippocampus.

The goal of the present study was to relate previously observed behavioral effects with changes in myelin in the hippocampus following exposure to the industrial solvent 1,1,2-trichloroethylene (TCE). Young adult rats exposed to TCE via their drinking water underwent tests to evaluate their ability to perform spatial navigational tasks, and their brains were examined for changes in myelin in the hippocampus. Exposure to an average daily load of 5.5 mg TCE first for 4 weeks and then to 8.5 mg for an additional 2 weeks (separated by a 2-week interval) resulted in an increased level of performance in spatial navigational tasks. Examination of the brains from these animals revealed a significant decrease in the amount of myelin in one layer of the hippocampus, the stratum lacunosum-moleculare. No increase in performance was observed in rats exposed to an average daily load of 5.5 mg TCE for 4 weeks only. A reduction in myelin was observed, however, in the stratum lacunosum-moleculare of these animals. This decrease was not as severe as that seen in the twice-exposed animals. The results of this study suggest that exposure to TCE results in a reduction of hippocampal myelin, and that this reduction may be related to the increased level of performance observed following a second exposure to TCE.

Animals↗
PubMedDate not supplied

Lead inhibits acquisition and retention learning in bullfrog tadpoles.

Bullfrog, Rana catesbeiana, tadpoles were exposed to 0, 500, 625, 750 or 100 micrograms Pb/L as lead nitrate, and subjected to learning and retention tests. Tadpoles used in learning acquisition tests were exposed for six days (144 hours) and tadpoles used in retention tests were exposed for five days (120 hours). All tadpoles were conditioned, using shock avoidance, to associate illumination (conditioned stimulus) with shock (unconditioned stimulus). The mean latency to respond, the number of avoidances, and the differences in learning curves of the lead-exposed and control tadpoles were compared statistically. Learning acquisition tests showed increased latencies and fewer avoidances in lead-exposed as compared to control tadpoles. Retention tests showed increased latencies and fewer avoidances in tadpoles exposed to 625, 750 and 1000 micrograms Pb/L as compared to controls.

Absorption↗
PubMedDate not supplied

Developmental neurotoxicity following premating maternal exposure to hexachlorobenzene in rats.

The maternal transfer of hexachlorobenzene (HCB) may place the developing organism at risk. The present study assessed the developmental neurotoxicity of HCB using a battery of behavioral tests. Two weeks prior to breeding, maternal rats were exposed via gavage to either 10 or 100 mg HCB/kg body weight. Behaviors evaluated in pups exposed maternally to HCB included the negative geotaxic reflex on postnatal day (PND) 6, 8, and 10, olfactory discrimination (PND 9-11), and the development of exploratory behavior (PND 15-20). Significant effects in these three tests indicated hyperactivity in HCB-exposed pups. No significant effects on learning (swim T-maze) or motor activity were detected in older offspring (PND 40 and 50 respectively). The acoustic startle response (ASR) revealed apparent age-related effects of maternal HCB exposure. On PND 23 pups from the high treatment group demonstrated significantly reduced ASR amplitude, whereas these same animals, tested on PND 90 (using a reflex modification design), showed elevated ASR amplitude relative to the controls. This work demonstrates that HCB is a behavioral teratogen, and suggests that human fetuses and suckling infants may be at risk from the neurotoxic effects of HCB.

Animals↗
PubMedDate not supplied

Behavioral avoidance of fluoranthene by fathead minnows (Pimephales promelas).

A monitoring system was used to examine the behavioral response of fathead minnows (Pimephales promelas) to plumes of the polycyclic aromatic hydrocarbon fluoranthene. Previously unexposed fish and fish surviving acute exposure to fluoranthene were presented with three different concentrations of fluoranthene. Both groups of fish avoided fluoranthene. Pre-exposure did not enhance or diminish avoidance of fluoranthene. The lowest concentration of fluoranthene which produced an avoidance response was 14.7 mu/l, and the concentration of fluoranthene which did not produce an avoidance response was 8.6 micrograms/l. These results were comparable to the LOEC for survival in 7-day fathead embryo-larval growth and survival tests for fluoranthene. Thus, a fathead minnow could escape from areas highly contaminated with fluoranthene and have a better opportunity to survive, whereas fish would fail to avoid areas where fluoranthene concentrations are below 8.6 micrograms/l and suffer further toxicosis.

Animals↗
PubMedDate not supplied

Air medical transport of patients from offshore oil and gas facilities. Historical accident data and initial experience.

The offshore petroleum exploration and production industry (OSI) is isolated from traditional means of access to emergent health care and may benefit from the unique attributes of helicopter air medical transport. This study was undertaken to review the incidence of OSI-related incidents, injuries and deaths, and report the initial experience of a civilian hospital-based helicopter air transport program in the evacuation of offshore patients. It was learned that the mean annual incidence of major OSI accidents from 1980 to 1986 was 19.1 (+/- 7.0). Mean annual mortality and reported injury were 14.7 (+/- 7.6) and 36.7 (+/- 25.4) patients respectively. Fires and explosions were the most frequently reported events at 62 per year (+/- 11.5/year). Nine OSI patients were evacuated by helicopter during the study's eight-month pilot period (seven for trauma and two for medical illness). One of the nine patients had been exposed to a potentially hazardous substance, requiring changes in the air medical team's operations, aircraft and equipment. The study shows that the offshore petroleum environment is ideally suited for air medical transport, as injuries are common and medical illnesses are to be expected. However, air medical programs operating offshore must deal with additional regulatory requirements and develop operational procedures to ensure safety during these flights.

Accidents, Occupational↗
PubMedDate not supplied

One state's response to the malpractice insurance crisis: North Carolina's Rural Obstetrical Care Incentive Program.

In the period 1985-89, there was a severe drop in obstetrical services in rural areas of North Carolina, partly because of rising malpractice insurance rates. The State government responded with the Rural Obstetrical Care Incentive (ROCI) Program that provides a malpractice insurance subsidy of up to $6,500 per participating physician per year. Enacted into law in 1988, the ROCI Program was expanded in 1991, making certified nurse midwives eligible to receive subsidies of up to $3,000 per year. To participate, practitioners must provide obstetrical care to all women, regardless of their ability to pay for services. Total funding for the program has increased from $240,000 to $840,000, in spite of extreme budgetary constraints faced by the State. The program and how its implementation has maintained or increased access to obstetrical care in participating counties are described on the basis of site visits to local health departments in participating counties and data from the North Carolina Division of Maternal and Child Health. The program is of significance to policy makers nationwide as both a response to rising malpractice insurance rates and reduced access to obstetrical care in rural areas, and as an innovative, nontraditional State program in which the locus of decision making is at the county level.

Female↗
PubMedDate not supplied

Low level lead (Pb) exposure produces learning deficits in young rat pups.

Eleven day old Sprague-Dawley (CD strain) rat pups whose mothers were maintained on a 200 mg/l dosage of lead (Pb) acetate in their drinking water from breeding and through gestation until the pups were weaned exhibited differences in a learning paradigm as compared to controls. No significant differences were noted between the control pups and the experimental pups with respect to acquisition rates but there were significant differences between the two groups with respect to extinction rates. Similar results were obtained in tests of rat pups whose dams had been maintained on a 400 mg/l dosage of lead (Pb) acetate. These data indicate that low level lead (Pb) exposure can induce significant behavioral deficits in young rat pups.

Animals↗
PubMedDate not supplied

Monomethyl-and trimethyltin compounds induce learning deficiencies in young rats.

Male rat pups were exposed to monomethyltin trichloride (MMTC) and trimethyltin chloride (TMTC) via their dams' drinking water throughout gestation and post partum until 21 days of age. At 11 days of age, the pups were tested for acquisition and extinction learning ability in an appetitive learning paradigm, and at 21 days for learning ability in a one trial swim escape learning test. At 11 days, pups from dams exposed to 120 mg/l Sn as MMTC and to 1.0 mg/l Sn as TMTC displayed statistically significant increases in acquisition time, while all dose groups (12, 40, 120 mg/l MMTC and 0.15, 0.5, 1.0 mg/l TMTC) displayed significant decreases in extinction learning ability as compared to controls. At 21 days of age, animals exposed to 12 mg/l and 120 mg/l MMTC displayed higher escape times than controls, as did animals exposed to 0.5 mg/l TMTC.

Animals↗