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Biomedical subjects

R Stephens

Publications and source records attributed to R Stephens.

At least 181 records · Page 10Linked to original sources

Organophosphates: the relationship between chronic and acute exposure effects.

The relationship between chronic (nonreversing) neuropsychological effects and acute exposure effects was investigated in 77 organophosphate exposed male sheep-dippers. Acute exposure effects were assessed prospectively using a purpose-constructed symptoms questionnaire administered pre-, and 24 h postexposure. Urine was analysed for dialkylphosphate levels to confirm recent exposure. Chronic effects were assessed in a cross-sectional neuropsychological study in the absence of recent exposure using computerised neuropsychological tests, the General Health Questionnaire, and the Subjective Memory Questionnaire. Simple correlation and multiple linear regression analyses (adjusting for confounders) were used to assess relationships between the change in total symptom reporting from baseline to 24 h after exposure and chronic effect outcomes. There was no evidence of any association between reported symptom levels and chronic neuropsychological effects. This suggests that chronic effects of OP exposure appear to occur independently of symptoms that might immediately follow acute OP exposure. This has implications for exposure control: individuals may experience chronic effects without the benefit of earlier warning signs of toxic effects during acute exposures.

Acute Disease↗

CD3+CD8+ cell levels as predictors of transmission in human immunodeficiency virus-infected couples: a report from the heterosexual HIV transmission study.

OBJECTIVE: The goal of this study was to identify in human immunodeficiency virus (HIV)-infected individuals immunologic markers that correlated with transmission of HIV by heterosexual contact. METHODS: In a case-control comparison of couples, immunologic and viral parameters were evaluated in 343 HIV-positive individuals who were members of 67 HIV-seroconcordant couples (both partners HIV positive) and 211 HIV serodiscordant couples (one positive, one negative). RESULTS: The most striking immunologic finding was the increased numbers of CD3+CD8+ cells found in the index member of discordant couples as compared to the index member of the concordant couples. Differences in CD3+CD8+ levels persisted after adjustment for stage of disease and CD3+CD4+ count. This increase in the number of CD3+CD8+ cells was accompanied by a concomitant decrease in the amount of viral replication measured by both HIV culture endpoint and quantitative RNA polymerase chain reaction (PCR). CONCLUSION: Data presented here further support the role of CD3+CD8+ cells in suppressing or controlling viral activity, although a causal role based on case-control data must be advanced cautiously. This in vivo biologic function may help prevent or lower the risk of HIV transmission.

Adolescent↗

Herpes simplex type II and Mycoplasma genitalium as risk factors for heterosexual HIV transmission: report from the heterosexual HIV transmission study.

OBJECTIVES: Two hundred twenty-four human immunodeficiency virus (HIV) discordant couples (one HIV negative, one HIV positive) were compared with 78 seroconcordant heterosexually infected couples with HIV with regard to sexually transmitted diseases. METHODS: Serologic testing and cultures were used to determine exposure of participants to sexually transmitted pathogens. These data were compared with HIV concordance of partners to investigate possible risk factors for HIV transmission. RESULTS: Syphilis, chlamydia, and hepatitis B virus (HBV) serologies did not distinguish between concordant and discordant couples nor did cultures for Neisseria gonorrhoeae and Trichomonas or Chlamydia enzyme immunoassay (EIA). Risk of transmission increased with positive serologies for herpes simplex virus (HSV)-2 (P = 0.002), cytomegalovirus (CMV) (P = 0.04), and Mycoplasma genitalium (P = 0.01), but not with Mycoplasma fermentans or Mycoplasma penetrans. Cytomegalovirus was not a significant risk factor when controlled for HSV-2 status. Examination by partner status showed increased risk of concordance with: HSV-2 positive serology in both partners (odds ratio [OR] = 3.14; confidence interval [CI] = 1.62-6.09; P = 0.007); HSV-2 in female secondary partner (OR = 2.10; CI = 1.12-3.93; P = 0.02) or the male primary partner (OR = 2.15; CI = 1.15-4.02; P = 0.017); M. genitalium antibody in both partners (OR = 3.44; CI = 1.68-7.04; P < 0.001); M. genitalium antibody in the primary male partner (OR = 2.51, CI = 1. 27-4.91; P = 0.008) and M. genitalium antibody in the secondary female partner (OR = 2.52; CI = 1.21-5.23; P = 0.01). CONCLUSIONS: These data support the role of HSV-2 in transmission of HIV and, for the first time, suggest a role for M. genitalium as an independent risk factor.

Adult↗

Tooth lead levels in Birmingham children.

The mean lead content of deciduous teeth from children living in the city of Birmingham (U.K.) has been shown to be 11.8 ppm dry weight, irrespective of the sex of the donor. Lead content varies according to type of tooth, and there is a gradient from incisors, with the highest level, to second molars, with the lowest. A relationship was shown between age of donor and lead content of canines and (when lognormalized data were considered) first molars. We were not able to demonstrate a correlation between tooth lead levels and residence near a potential industrial lead source, and we conclude that pollution from a general source is responsible for the body burdens we found.

Adolescent↗

Priming of CD4+ T cells and development of CD4+ T cell memory; lessons for malaria.

CD4 T cells play a central role in the immune response to malaria. They are required to help B cells produce the antibody that is essential for parasite clearance. They also produce cytokines that amplify the phagocytic and parasitocidal response of the innate immune system, as well as dampening this response later on to limit immunopathology. Therefore, understanding the mechanisms by which T helper cells are activated and the requirements for development of specific, and effective, T cell memory and immunity is essential in the quest for a malaria vaccine. In this paper on the CD4 session of the Immunology of Malaria Infections meeting, we summarize discussions of CD4 cell priming and memory in malaria and in vaccination and outline critical future lines of investigation. B. Stockinger and M.K. Jenkins proposed cutting edge experimental systems to study basic T cell biology in malaria. Critical parameters in T cell activation include the cell types involved, the route of infection and the timing and location and cell types involved in antigen presentation. A new generation of vaccines that induce CD4 T cell activation and memory are being developed with new adjuvants. Studies of T cell memory focus on differentiation and factors involved in maintenance of antigen specific T cells and control of the size of that population. To improve detection of T cell memory in the field, efforts will have to be made to distinguish antigen-specific responses from cytokine driven responses.

Animals↗

Neck dissection: radical or conservative.

Four hundred and forty-five neck dissections for epidermoid carcinoma over a 10-year period are reviewed as to local recurrence of neck disease. Three hundred and forty-seven dissections were radical en bloc procedures and in 98 a modified conservative technique was utilized. Cervical lymph node classification was applied and a comparison made of the two techniques. A review of the anatomy of cervical fascias and the technique of conservative neck dissection is given. Evaluation of this series of cases indicate that the control of local disease in the neck in the N0 and N1 groups is is accomplished as well with conservative dissection as with radical neck dissection. The number of conservative neck dissections for N2 disease was too limited for accurate comparison. There were no conservative neck dissections done for N3 disease. We suggest that conservative neck dissection be utilized for subclinical and N1 disease and that the classic en bloc dissection be reserved for N2 and N3 situations.

Carcinoma, Squamous Cell↗

Automated monitoring of outcomes: application to treatment of drug abuse.

This paper suggests a new approach for lowering follow-up costs, improving the delivery of health care, and monitoring treatment outcomes. An automated telephone follow-up system that calls, identifies, and interviews clients is an alternative method for monitoring patients that may be both reliable and cost-effective. To test the viability of such a system, the authors monitored a patient population that has historically been shown to be difficult to follow: recovering drug users and alcoholics. Forty-two subjects were asked to call the computer and complete interviews on a weekly basis for five months. Clients answered 25 recorded questions by pressing the keys on their telephone pads. The computer automatically analyzed the clients' answers and estimated a probability of relapse for each client. In addition, the computer automatically called subjects who failed to complete interviews at the scheduled times. The study showed that self-reported data collected by a computer are as reliable as data obtained through a written questionnaire and that clients are more willing to respond to computer interviews than to mailed written questionnaires. This study also provides preliminary data on the predictive ability of a questionnaire for predicting relapse.

Adult↗

Cost, quality, and reform.

In this era of change, hospitals and physicians must work closely together to identify new ways to respond to cost and quality issues.

Cost Control↗