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Biomedical subjects

R A Jenkins

Publications and source records attributed to R A Jenkins.

At least 19 recordsLinked to original sources
PubMed2003

Bioavailability and trophic transfer of sediment-bound Ni and U in a southeastern wetland system.

Elemental composition of soil, herbaceous and woody plant species, and the muscle and liver tissue of two common small mammal species were determined in a wetland ecosystem contaminated with Ni and U from nuclear target processing activities at the Savannah River Site, Aiken, SC. Species studied were black willow ( Salix nigra L.), rushes ( Juncus effusus L.), marsh rice rat ( Oryzomys palustris), and cotton rat ( Sigmodon hispidus). Two mature trees were sampled around the perimeter of the former de facto settling basin, and transect lines sampling rushes and trapping small mammals were laid across the wetland area, close to a wooden spillway that previously enclosed the pond. Ni and U concentrations were elevated to contaminant levels; with a total concentration of 1,065 (+/- 54) mg kg(-1) U and 526.7 (+/-18.3) mg kg(-1) Ni within the soil. Transfer of contaminants into woody and herbaceous plant tissues was higher for Ni than for U, which appeared to remain bound to the outside of root tissues, with very little (0.03 +/- 0.001 mg kg(-1)) U detectable within the leaf tissues. This indicated a lower bioavailability of U than the cocontaminant Ni. Trees sampled from the drier margins of the pond area contained more Ni within their leaf tissues than the rushes sampled from the wetter floodplain area, with leaf tissues concentrations of Ni of approximately 75.5 (+/- 3.6) mg kg(-1) Ni. Ni concentrations were also elevated in small mammal tissues. Transfer factors of contaminants indicated that U bioavailability is negligable in this wetland ecosystem.

Animals↗
PubMed2001

Meeting data quality objectives with interval information.

Immunoassay test kits are promising technologies for measuring analytes under field conditions. Frequently, these field-test kits report the analyte concentrations as falling in an interval between minimum and maximum values. Many project managers use field-test kits only for screening purposes when characterizing waste sites because the results are presented as semiquantitative intervals. However, field-test kits that report results as intervals can also be used to make project-related decisions in compliance with false-rejection and false-acceptance decision error rates established during a quantitative data quality objective process. Sampling and analysis plans can be developed that rely on field-test kits to meet certain data needs of site remediation projects.

Data Collection↗
PubMed2001

Environmental tobacco smoke in the nonsmoking section of a restaurant: a case study.

This study tested the concentrations of environmental tobacco smoke (ETS) components in a small restaurant/pub with smoking and nonsmoking areas-a facility outfitted with a heat-recovery ventilation system and directional airflow. The ETS levels in the nonsmoking area were compared with those in other similar restaurants/pubs where indoor smoking is altogether prohibited. The results indicate that ETS component concentrations in the nonsmoking section of the facility in question were not statistically different (P < 0.05) from those measured in similar facilities where smoking is prohibited. The regulatory implications of these findings are that ventilation techniques for restaurants/pubs with separate smoking and nonsmoking areas are capable of achieving nonsmoking area ETS concentrations that are comparable to those of similar facilities that prohibit smoking outright.

Air Pollutants↗
PubMed2001

Factors associated with Army obstetricians-gynecologists' practice of HIV prevention education during routine gynecologic care.

The authors evaluate obstetricians-gynecologists' (OB-GYNs') anxiety about clinical uncertainty and patient, physician, and organizational factors associated with their selection of HIV-related educational activities for high-risk and low-risk written case simulations. A total of 117 U.S. Army OB-GYNs completed a mailed, anonymous questionnaire. Overall, informants were much less likely to educate in response to the low-risk simulation; however, more informants who were anxious about uncertainty were more likely to do so in a model that included supportive institutional policies, willingness to educate despite patient barriers, and comfort with the topic. OB-GYNs were more likely to educate in response to the high-risk simulation given greater willingness to discuss HIV despite organizational barriers, supportive policies, and comfort. Findings suggest a need to better understand the role that anxiety about uncertainty plays in HIV prevention and the need to promote organizational policies that support and remove barriers to clinically based education.

Anxiety↗
PubMed2000

Reducing risk of sexually transmitted disease (STD) and human immunodeficiency virus infection in a military STD clinic: evaluation of a randomized preventive intervention trial.

Three single-session preventive interventions for reducing sexually transmitted disease (STD) and human immunodeficiency virus infection risk behaviors were evaluated with a sample of 400 men who attended a large military STD clinic. A quasi-experimental, pre-evaluation/postevaluation design was used, comparing standard clinic care alone versus standard care combined with 1 of 3 experimental interventions: health-risk appraisal, interactive video, and targeted situational behaviors. Questionnaire data were collected at baseline and during follow-up visits at 2 weeks and 2 months. Findings indicated that the health-risk appraisal and interactive video increased adherence with clinic recommendations to abstain from sex (chi(2)3199=19.67; P<.001) and increased readiness to change "risky" partner-selection behavior (chi(2)2194=6.42; P<.04). Follow-up data suggested that STD-related risk behavior was particularly resistant to change but that the single-session intervention had some impact, which could be viewed as a "priming" effect that enhances multisession interventions.

Adult↗
PubMed2000

Features of urethritis in a cohort of male soldiers.

Of 400 cases of urethritis in male soldiers enrolled in a behavioral intervention project, the etiology of 69% was defined at study enrollment, as well as the etiology of 72% of 25 repeated episodes involving 21 men during the first 78 days of active follow-up (5% of the cohort). Chlamydia trachomatis (36%), Neisseria gonorrhoeae (34%), and Ureaplasma urealyticum (19%) were the most common causes of infection identified at enrollment and during subsequent visits (44%, 28%, and 12%, respectively). By univariate analysis, patients with repeated infection ("repeaters") were significantly more likely to report a history of sexually transmitted disease (STD; relative risk [RR], 3) and sex with sex workers (RR, 4) than were nonrepeaters. By multivariate analysis, only STD history was significant (RR, 2.8). Characteristics of repeaters in this cohort suggest that specific patterns may be used to establish screening "profiles" of potential repeaters, by which such individuals might be targeted for aggressive intervention at the time of the initial diagnosis.

Adult↗
PubMed2000

Determination of cocaine and heroin vapor pressures using commercial and illicit samples.

The establishment of drug vapor pressure reference values provides valuable information in the development of vapor sensing devices for drug detection. The purpose of this work was to determine equilibrium headspace vapor pressures for commercial and illicit drug samples for use in such applications. Samples of cocaine, both free base and hydrochloride forms, and heroin hydrochloride were evaluated. The procedure used to measure the vapor pressures was a modification of a previously published method. Vapor pressure values at 20 degrees C previously reported for cocaine free base range from 0.37 x 10(-7) to 1.20 x 10(-7) Torr. The vapor pressure value determined in this study was 2.96 x 10(-7) Torr. It is likely that the discrepancies are due to differences in experimental conditions, varying sources of samples, and uncertainty in the methodologies. When the values were compared for commercial (99% purity) and illicit (unknown purity) sources of cocaine free base, there were no statistical differences in the projected room temperature (20 degrees C) vapor pressure values. However, the commercial and illicit samples of cocaine hydrochloride did show statistical differences. Although no comparison was made with the vapor pressure values for a pure, commercial sample, the vapor pressures of heroin hydrochloride (81% purity) at various temperatures were determined using the method developed for cocaine and are reported in this paper.

Cocaine-Related Disorders↗
PubMed2000

Correlates of human immunodeficiency virus infection risk behavior in male attendees of a clinic for sexually transmitted disease.

Human immunodeficiency virus (HIV) infection risk behavior was evaluated in a cross-sectional survey of 400 male active-duty US Army personnel who presented at a sexually transmitted disease (STD) clinic with symptoms of acute urethritis. High-risk partners were common, and nearly one-quarter of the sample had previously had STDs. Logistic regression models examined correlates of HIV exposure risk, of inconsistent condom use, and of having partners with increased risk of HIV infection. Frequent partner turnover, sex "binging," negative attitudes toward condom use, and engaging in sex during military leaves were important correlates of risk. Individuals with HIV infection risk behavior generally were cognizant of their risk for HIV infection. Implications for intervention are discussed.

Condoms↗
PubMed2000

Willingness to participate in HIV-1 vaccine trials among young Thai men.

OBJECTIVES: Willingness to participate in HIV-1 vaccine trials and associated factors were investigated in a sample of 2670 Royal Thai Army conscripted recruits. METHODS: Self administered questionnaires were used. Data were collected during the final visit of a longitudinal cohort study of HIV-1 epidemiology. Cross sectional analysis of data from this visit was performed. RESULTS: 32% of the respondents reported they would "definitely" join an HIV-1 vaccine trial. Greater willingness was associated with perceived risk of HIV-1 infection and a desire to help Thai society, although tangible incentives and intentions to reduce condom use in a vaccine trial also were associated with increased willingness. Concerns about physical harm and anticipated social pressure from family not to join were the most substantial impediments to willingness. Concerns about "social harm" (for example, participation would give appearance of having AIDS virus, a partner might refuse sex) also appeared to inhibit interest in joining trials and approached significance. CONCLUSIONS: Willingness to participate was somewhat greater than in other investigations of non-injection drug user (IDU) cohorts in Thailand, with fewer concerns expressed about physical harm. Motivations appear to involve tradeoffs among perceived risk, anticipated social pressure, altruism, and tangible rewards. The absence of significant problems associated with vaccine trials to date, along with the presence of educational interventions in the study may help explain the lower level of concerns here relative to other Thai studies.

AIDS Vaccines↗
PubMed1999

Evaluation of behavioral and social issues among Thai HIV vaccine trial volunteers.

Behavioral and social issues were investigated in phase I/II preventive HIV vaccine trial volunteers in Thailand. These included risk behavior, HIV knowledge, distress, and social experiences associated with trial participation. Data were collected at baseline and at 4- and 8-month follow-up visits. Volunteers reported relatively low levels of risk behaviors at baseline and at the follow-up visits. About one fifth reported overtly negative reactions from family or friends. No problems with discrimination in employment, health care, or insurance were reported. Findings add to the evidence suggesting the feasibility of phase I/II prophylactic HIV vaccine trials with low-risk volunteers in Thailand.

AIDS Vaccines↗
PubMed1999

Exposure to environmental tobacco smoke in the workplace and the impact of away-from-work exposure.

Concentrating on exposure in workplaces where smoking occurs, we examined environmental tobacco smoke (ETS)-related concentration data from the 16-City Study. This study involved a large population of nonsmokers, used personal monitors, and encompassed a wide selection of ETS-related constituents. This first article in a series of three describes the 16-City Study, considers the impact of demographic variables, and concludes that these variables did not explain differences in exposure to ETS. We compared 16-City Study concentrations obtained in the workplace to previously reported workplace concentrations and determined that data from this study were representative of current ETS exposure in nonmanufacturing workplaces where smoking occurs. Considering factors other than demographic factors, we found that, not surprisingly, the number of cigarettes observed in the workplace had an impact on exposure concentrations. Finally, we compared people from homes where smoking occurs with people from nonsmoking homes and found that people from smoking homes observed more smoking in the workplace and experienced higher concentrations of ETS-related compounds in the workplace, even when they observed the same number of cigarettes being smoked in the workplace. In two subsequent articles in this series, we discuss relationships between various ETS markers and provide estimates of distributions of doses to nonsmoking workers employed in workplaces where smoking occurs.

Adult↗
PubMed1999

Distribution of exposure concentrations and doses for constituents of environmental tobacco smoke.

The ultimate goal of the research reported in this series of three articles is to derive distributions of doses of selected environmental tobacco smoke (ETS)-related chemicals for nonsmoking workers. This analysis uses data from the 16-City Study collected with personal monitors over the course of one workday in workplaces where smoking occurred. In this article, we describe distributions of ETS chemical concentrations and the characteristics of those distributions (e.g., whether the distribution was log normal for a given constituent) for the workplace exposure. Next, we present population parameters relevant for estimating dose distributions and the methods used for estimating those dose distributions. Finally, we derive distributions of doses of selected ETS-related constituents obtained in the workplace for people in smoking work environments. Estimating dose distributions provided information beyond the usual point estimate of dose and showed that the preponderance of individuals exposed to ETS in the workplace were exposed at the low end of the dose distribution curve. The results of this analysis include estimations of hourly maxima and time-weighted average (TWA) doses of nicotine from workplace exposures to ETS (extrapolated from 1 day to 1 week) and doses derived from modeled lung burdens of ultraviolet-absorbing particulate matter (UVPM) and solanesol resulting from workplace exposures to ETS (extrapolated from 1 day to 1 year).

Absorption↗
PubMed1999

Use of environmental tobacco smoke constituents as markers for exposure.

The 16-City Study analyzed for gas-phase environmental tobacco smoke (ETS) constituents (nicotine, 3-ethenyl pyridine [3-EP], and myosmine) and for particulate-phase constituents (respirable particulate matter [RSP], ultraviolet-absorbing particulate matter [UVPM], fluorescing particulate matter [FPM], scopoletin, and solanesol). In this second of three articles, we discuss the merits of each constituent as a marker for ETS and report pair-wise comparisons of the markers. Neither nicotine nor UVPM were good predictors for RSP. However, nicotine and UVPM were good qualitative predictors of each other. Nicotine was correlated with other gas-phase constituents. Comparisons between UVPM and other particulate-phase constituents were performed. Its relation with FPM was excellent, with UVPM approximately 1 1/2 times FPM. The correlation between UVPM and solanesol was good, but the relationship between the two was not linear. The relation between UVPM and scopoletin was not good, largely because of noise in the scopoletin measures around its limit of detection. We considered the relation between nicotine and saliva continine, a metabolite of nicotine. The two were highly correlated on the group level. That is, for each cell (smoking home and work, smoking home but nonsmoking work, and so forth), there was high correlation between average continine and 24-hour time-weighted average (TWA) nicotine concentrations. However, on the individual level, the correlations, although significant, were not biologically meaningful. A consideration of cotinine and nicotine or 3-EP on a subset of the study whose only exposure to ETS was exclusively at work or exclusively at home showed that home exposure was a more important source of ETS than work exposure.

Age Factors↗
PubMed1999

Occupational exposure to environmental tobacco smoke: results of two personal exposure studies.

Personal monitoring is a more accurate measure of individual exposure to airborne constituents because it incorporates human activity patterns and collects actual breathing zone samples to which subjects are exposed. Two recent studies conducted by our laboratory offer perspective on occupational exposure to environmental tobacco smoke (ETS) from a personal exposure standpoint. In a study of nearly 1600 workers, levels of ETS were lower than or comparable to those in earlier studies. Limits on smoking in designated areas also acted to reduce overall exposure of workers. In facilities where smoking is permitted, ETS exposures are 10 to 20 times greater than in facilities in which smoking is banned. Service workers were exposed to higher levels of ETS than workers in white-collar occupations. For the narrower occupational category of waiters, waitresses, and bartenders, a second study in one urban location indicated that ETS levels to which wait staff are exposed are not considerably different from those exposure levels of subjects in the larger study who work in environments in which smoking is unrestricted. Bartenders were exposed to higher ETS levels, but there is a distinction between bartenders working in smaller facilities and those working in multiroom restaurant bars, with the former exposed to higher levels of ETS than the latter. In addition, ETS levels encountered by these more highly exposed workers are lower that those estimated by the Occupational Safety and Health Administration. Concomitant area monitoring in the smaller study suggests that area samples can only be used to estimate individual personal exposure to within an order of magnitude or greater.

Adult↗
PubMed1998

Sexual behavior of young men in Thailand: regional differences and evidence of behavior change.

An anonymous, self-administered behavioral survey was conducted in Royal Thai Army (RTA) conscripts from 19 provinces throughout Thailand in May 1996. All (to a maximum of 350) Thai men who entered the RTA in each province were selected. Data from 5474 men were included in this analysis. High-risk behaviors were reported nationwide; however, some regional differences were found. Men from the upper North were more likely to have had a commercial sex worker (CSW) as their first sexual partner (42%) than men from any other region. However, in the past year, reported sex with CSWs in the upper North (41%) was similar to or lower than those in other regions. Consistent condom use with CSWs was higher in the North than in any other region. Condom use at first sex with CSWs increased with later years at first sex in all regions. These data suggest that past higher-risk behavior among young men in the upper northern part of Thailand may have contributed to the concentration of the HIV epidemic in that region. Risk behaviors, particularly unprotected sex, appear to be decreasing nationwide.

Adult↗
PubMed1998

Motivation, recruitment, and screening of volunteers for a phase I/II HIV preventive vaccine trial in Thailand.

Data from recruitment and screening for a phase I/II preventive HIV-1 vaccine trial in Thailand were evaluated with respect to correlates of participation at each phase. Correlates included demographic variables, motivation for interest in the trial, and factors related to communication and contact. Participants were recruited at two sites through varied methods. The majority of prescreenees reported altruistic motives for interest in the trial and blood donors emerged as a group that may have been particularly altruistic. Findings indicated site differences in attrition during recruitment and screening, but not in enrollment into the vaccine trial. Blood donation and willingness to be contacted by phone at home were significantly related to making and keeping screening appointments.

AIDS Vaccines↗
PubMed1996

Determination of personal exposure of non-smokers to environmental tobacco smoke in the United States.

The potential health effects of exposure to environmental tobacco smoke (ETS) is a controversial subject, especially in the United States. Most studies on this subject have relied on reports of exposure from interviews or from questionnaires administered to the subjects. Other studies have derived data from actual measurements of markers of ETS in areas where tobacco products, especially cigarettes, are "being smoked" and the exposure of the subjects have been extrapolated from the values obtained. In this study, measurements of airborne ETS markers were made in approximately 1000 non-smokers in the US, who wore personal air sampling systems "at work" and "away from work". Participants in this study stated that they had not used tobacco products, nicotine patches, or nicotine gum for at least 6 months. It was found that the largest concentrations of ETS markers were encountered "away from work" and that, in general, the amount of ETS to which the subjects were exposed was markedly lower than those estimated in previous studies. Additionally, it appears that there is an important difference between the exposure to ETS perceived by participants and the actual exposures measured in this study.

Adult↗