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Biomedical subjects

L F Barker

Publications and source records attributed to L F Barker.

At least 19 recordsLinked to original sources
PubMed2003

Evaluation of an extensive tuberculosis contact investigation in an urban community and jail.

SETTING: Urban community and jail. OBJECTIVES/DESIGN: Evaluate outcome and process of an extensive tuberculosis contact investigation, including completion of treatment of latent TB infection (TLTBI). RESULTS: Between April 2000 and September 2001, 18 epidemiologically-linked tuberculosis cases were identified; 15 were culture-confirmed, all with a matching 14-band DNA fingerprint pattern. The source case had cavitary pulmonary disease and had been incarcerated 4 months prior to diagnosis. Sixty-six of 67 (99%) community contacts and 221/344 (64%) jail contacts were evaluated. The presumed new infection rate was 56% for community contacts (11 cases, 25 tuberculin skin test [TST] positive) and 20% for jail contacts (6 cases, 32 TST converters). Screening results for 113 (33%) jail contacts were obtained in the jail TST registry upon rearrest. All identified cases completed treatment. Of 22 community contacts initiating TLTBI, 11 completed (44% of infected, 50% of initiators). Of 32 infected jail contacts, 12 initiated TLTBI (all who remained incarcerated), and 10 completed (31% of infected, 83% of initiators). None of 20 additional in-fected jail contacts, all of whose TST conversions were identified with re-arrest data, were subsequently located. Two additional related cases have been identified as of October 2003. CONCLUSIONS: Close health department/corrections collaboration facilitated this extensive contact investigation, which identified high Mycobacterium tuberculosis transmission rates and controlled the outbreak. Numerous contacts were identified and screened, but rates of treatment completion for infected contacts were low. Novel strategies are needed to maximize the number of infected contacts who are not only identified and evaluated, but completely treated.

Adolescent↗
PubMed2000

Development of a pollution prevention and energy efficiency clearinghouse for biomedical research facilities.

This is the report of the National Association of Physicians for the Environment Committee on Development of a Pollution Prevention and Energy Efficiency Clearinghouse for Biomedical Research Facilities from the Leadership Conference on Biomedical Research and the Environment held at the National Institutes of Health in Bethesda, Maryland, on 1--2 November 1999. A major goal of the conference was the establishment of a World Wide Web-based clearinghouse, which would lend tremendous resources to the biomedical research community by providing access to a database of peer-reviewed articles and references dealing with a host of aspects of biomedical research relating to energy efficiency, pollution prevention, and waste reduction. A temporary website has been established with the assistance of the U.S. Environmental Protection Agency (EPA) Regions III and IV, where a pilot site provides access to the EPA's existing databases on these topics. A system of peer review for articles and promising techniques still must be developed, but a glimpse of topics and search engines is available for comment and review on the EPA Region IV-supported website (http://wrrc.p2pays.org/).

Biomedical Technology↗
PubMed1999

Polychlorinated biphenyls (PCBs) selectively disrupt serotonergic cell growth in the developing Spisula embryo.

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that exert neurotoxic effects during embryonic development. The present study demonstrates that early embryonic exposure to a mixture of PCBs (Aroclor 1254) results in a decrease in serotonergic cell growth. Using a novel, marine invertebrate embryo model, Spisula solidissima, immunocytochemistry, and confocal microscopy techniques, a dose-dependent decrease in serotonergic cell number was quantified within 24 h of exposure. This effect was seen with doses as low as 1 ppm Aroclor 1254. These findings demonstrate that environmentally relevant doses of Aroclor 1254 impair development of the serotonergic nervous system.

Animals↗
PubMed1996

Transmission of serum hepatitis. 1970.

There is evidence that transmission of serum hepatitis is associated with transmission of virus-like particles, approximately, 20 millimicron in diameter, containing the Australia or serum hepatitis (SH) antigen, which is currently referred to as the hepatitis associated antigen (HAA). Virus-like particles containing HAA were in the following materials, inoculation of which produced serum hepatitis: (1) a pool of human plasma, (2) serum obtained during the acute phase of hepatitis from a recipient of the plasma pool, (3) a preparation of human thrombin, and (4) serum from a proved hepatitis carrier. The HAA appeared in the serum samples of 61 individuals inoculated with these materials; serum hepatitis developed in 38 of them. Inoculation of dilutions of the plasma pool showed that serum hepatitis can be transmitted by materials containing HAA in amounts too low to be detected by current techniques.

Carrier State↗
PubMed1995

Trial objectives and end points for measuring the efficacy of HIV vaccines.

In order to prove the efficacy of human immunodeficiency virus (HIV) vaccines, it will be necessary to do large-scale trials in populations at high risk of acquiring HIV infection. The choice of objectives and end points and their measurement will be key to the design of efficacy trials. To address these issues, the National Institute of Allergy and Infectious Diseases convened several workshops and discussions at national meetings. These discussions have concluded that many factors will contribute to the selection of practical primary objectives and end points for efficacy trials of HIV vaccines. For initial trials the objective of preventing the establishment of chronic infection is a reasonable choice, given the current state of knowledge. However, given the complexities of HIV and the acquired immunodeficiency syndrome, it will be important to collect data and evaluate other potential objectives and end points as well.

AIDS Vaccines↗
PubMed1982

Anaphylactoid reactions to Escherichia coli and Erwinia asparaginase in children with leukemia and lymphoma.

The incidence and clinical characteristics of anaphylactoid reactions to intravenous asparaginase were assessed in 196 patients given E. coli asparaginase and 49 patients given Erwinia asparaginase. All patients were given a 50 IU intravenous test dose followed in 30 min by the full dosage (10,000 IU/m2), if no reaction occurred to the test dose. Twenty-nine of 196 patients (14.8%) given E. coli asparaginase had an anaphylactoid reaction, occurring after their first through 12th doses. The probability of an anaphylactoid reaction was significantly greater in those patients not receiving concomitant prednisone-vincristine and patients with a hiatus between courses of asparaginase therapy. By logistic regression analysis, other variables such as age, sex, race, diagnosis, total number of doses and concurrent methotrexate or arabinosylcytosine did not contribute significantly to the probability of a reaction. Twenty-three of the patients who had reacted to E. coli asparaginase and 26 patients who had not reacted to E. coli asparaginase were subsequently given Erwinia asparaginase. Seven of these 49 patients (14%) had an anaphylactoid reaction. The probability of a reaction to Erwinia asparaginase was significantly related to a prior reaction to E. coli asparaginase, concomitant prednisone-vincristine therapy, total number of asparaginase doses, number of prior E. coli asparaginase doses, and diagnosis, when assessed by a logistic regression model. However, after adjusting for prior reaction to E. coli asparaginase and the total number of asparaginase doses given, the other variables did not contribute significantly to the probability of a reaction. Only 5/29 patients reacting to E. coli asparaginase and 1/7 reacting to Erwinia asparaginase had a reaction to the test dose. None of the reactions were fatal.

Adolescent↗
PubMed1982

Hepatitis-associated markers in the American Red Cross volunteer blood donor population. IV. A comparison of HBV-associated serologic markers in HBsAg-positive first-time and repeat blood donors.

The present study was undertaken to determine whether there were any differences in the distribution of hepatitis B virus-(HBV) associated serologic markers among hepatitis B surface antigen-(HBsAg) positive first-time and repeat blood donors. The markers examined in samples from 412 newly identified HBsAg-positive donors (254 first-time and 158 repeat) included HBsAg titer and subtype, HBeAg/anti-HBe, and anti-HBc. Repeat donors were more frequently HBeAg-positive (25.9%) than were first-time donors (17.7%). Anti-HBc and anti-HBe were observed more often among first-time (99.6 and 76%) than repeat (91.8 and 60.8%) donors. No differences were found in the mean HBsAg titer nor in the subtype distribution in the two populations. The frequency of HBeAg positivity and the mean HBsAg titer in blood were significantly lower among first-time donors aged 30 or older as compared to those younger than 30. Such age-related tendencies did not occur among the repeat donors. The profiles of HBV makers suggest that the HBsAg-positive first-time donor group consists predominantly of long-term HBsAg carriers who may have acquired HBV at an early age, while the HBsAg-positive repeat donors have newly acquired infections.

Adolescent↗
PubMed1981

Failure to detect infectious hepatitis B virus using high dose safety test for hepatitis B vaccine.

One hundred milliliters of an inactivated hepatitis B vaccine (20 microgram/ml) were inoculated intravenously into two colony-born infant chimpanzees. Immediately thereafter each received hepatitis B virus from a documented infectious inoculum intravenously at a separate site. Neither chimpanzee developed elevation of aminotransferase levels, hepatitis B surface antigen (HBsAg), or antibody to hepatitis B core antigen during six months of evaluation, the duration of the currently recommended safety test. Both chimpanzees developed antibody to HBsAg beginning 8 and 9 weeks, respectively, after inoculation. The administration of a large intravenous quantity of vaccine antigen thus appeared capable of masking or preventing infection by simultaneously administered hepatitis B virus. This study suggests that a chimpanzee safety test for hepatitis B vaccine should not employ large quantities of vaccine antigen, since such a safety test may fail to detect small amounts of residual infectious hepatitis B virus.

Animals↗
PubMed1981

Comparative evaluation of radioimmunoassay kits used for testing blood for hepatitis B surface antigen.

A comparative evaluation of six licensed radioimmunoassay kits for the detection of hepatitis B surface antigen (HBsAg) has been performed. Each method met the federal licensure requirements for the test. The performance of the kits varied considerably, however, when they were challenged to the limits of their sensitivities. During the period December 1978 through March 1979, four kits were judged to be of equivalent high sensitivity, whereas two were less sensitive. Three of the kits, including two of those with high sensitivity, generated a high (6%--7%) proportion of false reactive results. The sensitivities of all kits decreased during the shelf lives of the reagents.

Evaluation Studies as Topic↗