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Biomedical subjects

Zena Stein

Publications and source records attributed to Zena Stein.

13 recordsLinked to original sources
PubMed2006

Sensitivity analysis and potential uses of a novel gamma interferon release assay for diagnosis of tuberculosis.

Sputum smears for acid-fast bacilli (AFB) are the primary methods for diagnosis of tuberculosis (TB) in many countries. The tuberculin skin test (TST) is the primary method for diagnosis of latent TB infection (LTBI) worldwide. The poor sensitivity of the former and the poor specificity of the latter warrant the development of new tests and strategies to enhance diagnostic capabilities. We evaluated the sensitivity of an "in-tube" gamma interferon release assay (IGRA) using TB-specific antigens in comparison to the TST and the sputum smear for AFB in TB cases in South Africa. The sensitivity of the IGRA for TB was considered a surrogate of sensitivity in LTBI. Among 154 patients with a positive culture for Mycobacterium tuberculosis, the sensitivity of the IGRA for the diagnosis of TB varied by clinical subgroup from 64% to 82%, that of the TST varied from 85% to 94%, and that of two sputum smears for AFB varied from 35% to 53%. The sensitivity of the IGRA in human immunodeficiency virus (HIV)-infected TB cases was 81%. HIV-infected TB patients were significantly more likely to have indeterminate IGRA results and produced quantitatively less gamma interferon in response to TB-specific antigens than HIV-negative TB patients. The overall sensitivity of the TST in all TB cases was higher than that of the IGRA (90% versus 76%, respectively). The combined sensitivities of the TST plus IGRA and TST plus a single sputum smear were 96% and 93%, respectively. The TST combined with IGRA or with a single sputum smear may have a role in excluding the diagnosis of TB in some settings.

Adult↗
PubMed2005

Microbicide acceptability research: current approaches and future directions.

With growing recognition of the potential value of microbicides for HIV/STI prevention, the importance of the acceptability of this brand-new technology has been widely acknowledged. We review the current body of microbicide acceptability research, characterize the limitations in assessment approaches, and suggest strategies for improvement. Electronic databases and abstracts of recent meetings were searched for acceptability data regarding vaginal and rectal products that may be used for HIV prevention. Of the 61 studies reviewed, more than half assessed acceptability based primarily on the description of a hypothetical microbicide, or with the demonstration of a spermicide or lubricant. Physical characteristics of microbicidal products, their effects after insertion, and their effects on sensation during intercourse (for both partners) were the dimensions most frequently assessed (measured in 77%, 49% and 49% of studies, respectively). Attention to the social context of use was inadequate. As acceptability is likely to be a key determinant in the use-effectiveness of microbicides, in-depth understanding of the social processes that shape microbicide acceptability across diverse populations will become increasingly valuable. This includes exploring the effects that sexual partners, health care providers, and key opinion leaders have on the acceptability of microbicides among women and men, including youth and people living with HIV. Future research will benefit from studies of the acceptability of other contraceptive-barrier methods (especially the female condom), use of an agreed-upon operationalization of acceptability, use of acceptability assessments within clinical trials, expansion of measurement domains, and assessment of changes in perceptions of acceptability and use over time. Failure to understand the key factors associated with microbicide acceptability is likely to hinder the adoption and continued use of products that are effective in preventing HIV infection.

Anti-Infective Agents, Local↗
PubMed2004

Preventing mother-to-child HIV transmission in the new millennium: the challenge of breast feeding.

Short courses of antiretroviral drugs have greatly enhanced the prospect of reducing mother-to-child HIV transmission. Yet transmission by breast feeding clouds hopes for this seemingly simple intervention. We revisit mathematical models to assess the competing risks associated with feeding by breast vs. formula. These indicate that, in the less developed world where the HIV epidemic predominates, neither option, unmodified, offers a reasonable choice for HIV-positive women. Where infant mortality rates are greater than about 40 per 1000 live births, if formula were made available to HIV-infected women only, the excess number of deaths that would result from formula use would be approximately the same or greater than the number of HIV infections that might be prevented. Only at lower infant mortality rates, less than about 40 per 1000, is the risk greater on the breast. There are thus no good grounds for the total avoidance of breast feeding under all conditions. Research to develop and test safer infant feeding alternatives is an urgent priority. On the one hand, ways to reduce HIV transmission while preserving breast feeding, as exclusive breast feeding could do, need to be fully tested. On the other hand, ways to reduce non-HIV morbidity and mortality associated with formula feeding, as educational or sanitary interventions could do, equally need testing. With either approach, a necessary foundation for implementing all the core components of preventing mother-to-child HIV transmission is competent counselling for mothers. Innovative approaches are needed to mobilise and train effective counsellors among health care workers and, as appropriate, community members.

Breast Feeding↗
PubMed2003

Female-condom use in a gender-specific family planning clinic trial.

OBJECTIVES: We evaluated female-condom use among women participating in an HIV/STD intervention designed to reduce unprotected sex and expand prevention strategies. METHODS: Women (n = 360) were recruited from a family-planning clinic and were randomized into an 8- or 4-session intervention group or a control group. We conducted follow-up interviews at 1, 6, and 12 months. RESULTS: At 1 month, the odds ratios of first-time female-condom use were 9.49 (95% confidence interval [CI] = 4.01, 22.20) in the 8-session group and 4.39 (95% CI = 1.84, 10.49) in the 4-session group relative to controls. Repeated use (n = 21) was predicted by perceived ability to use, by self and partner satisfaction, by dislike of male condoms, and by previous diaphragm use. CONCLUSIONS: Gender sensitive cognitive-behavioral interventions can influence women to try the female condom. To increase long-term use, interventions may need to include self-insertion practice and involvement of male partners.

Single-Use Internal Condom↗