Cytotoxic T-cell activity is not detectable in Venezuelan equine encephalitis virus-infected mice.

Previously published research has established that the immune response to the Venezuelan equine encephalitis virus (VEEV) vaccine strain TC-83 is Th 1-mediated, with local activation of both CD4+ and CD8+ T cells. This suggests that cytotoxic lymphocytes CTL may play a role in protection against virulent VEEV. Studies involving a variety of immunisation schedules with either TC-83 or strain CAAR 508 (serogroup 5) of VEEV, and six different haplotypes of mice, failed to reveal functional CTL activity against VEEV-infected targets in secondary antigen-stimulated lymphocyte cultures from either the draining lymph nodes (LN) or spleen. Nor were VEEV-specific CTL detected after immunisation of mice (three haplotypes) with recombinant vaccinia viruses (VV) expressing either the non-structural (nsP1-4) or the structural (C-E3-E2-6K-E1) genes of TC-83. Reciprocal experiments in which mice were immunised with TC-83, and their lymphocytes tested against VV recombinant-infected targets also failed to detect CTL activity. These data suggest that VEEV infection of mice does not elicit detectable CTL activity, and that CTL are unlikely to play a role in protection against virulent VEEV.

PCR detection of Clostridium chauvoei in pure cultures and in formalin-fixed, paraffin-embedded tissues.

The polymerase chain reaction (PCR) was used to amplify specific segments of the 16S ribosomal RNA gene of Clostridium chauvoei, a major pathogen of ruminants. Three sets of primers were used to produce amplicons of 159, 836 and 959 base pairs (bp), respectively. The PCR was evaluated by testing clinically important strains of Clostridium, including 21 strains of C. chauvoei, five strains each of Clostridium septicum and Clostridium perfringens and two strains each of Clostridium novyi, Clostridium histolyticum and Clostridium sordellii. Both purified DNA and biomass from pure cultures of each of these microorganisms were evaluated as templates in the PCR. In addition, extracts of formalin-fixed, paraffin-embedded tissues of eight sheep experimentally inoculated with C. chauvoei or C. septicum (four animals each) were also tested by the PCR using the three sets of primers. Purified DNA template of all C. chauvoei strains produced PCR amplicons of the expected size for all three primer pairs. However, when biomass from pure cultures of C. chauvoei or tissue extracts were used as templates, only the primer pair designed to produce the 159bp amplicon gave consistently positive results. No positive results were obtained with any primer pair when purified DNA or biomass from pure cultures of non-target clostridial species were used as templates. Therefore, the PCR primer sets appear to be very specific for identifying C. chauvoei in both cultures and tissues.

Cervical cancer screening in developing countries: why is it ineffective? The case of Mexico.

BACKGROUND: Mexico established a national cervical cancer-screening program in 1974. Despite the implementation of the program, there was a steady mortality trend of 16 per 100,000 women over 15 years. METHODS: A diagnostic procedure of the pitfalls was applied to the following steps of the screening procedure: Pap sampling quality; cytological diagnosis validity; compliance of women; and determinants of non-participation. RESULTS: The low effectiveness of screening on cervical cancer is principally due to factors associated with quality and coverage. Pap quality is deficient; 64% of a random sample of specimens lacked endocervical cells. Reading centers presented false negative indices of between 10 and 54%. Women seek screening in a late stage of disease (55% with cervical cancer seek care because they have symptoms). In addition, coverage is low; in women between 15 and 49 years of age in Mexico City, 64.2% have a history of Pap, compared with 30% in rural areas. Knowledge of what the Pap is used for strongly determines the use of screening. In rural areas, only 40% of women are informed about the purpose of the Pap test. CONCLUSIONS: A proposal to reorganize Mexico's screening program includes the following five main strategies: (a) increased coverage; (b) improved quality control of how cervical smears are taken; (c) better interpretation of Pap tests; (d) guaranteed treatment for those whose tests show abnormalities, and (e) improved follow-up.

[The factors that determine participation in cervical cancer screening in the state of Morelos]. / Factores que determinan la participación en el tamizaje de cáncer cervical en el estado de Morelos.

OBJECTIVE: To determine the main factors associated to participation in an early detection program of cancer (DPC), in a population with a high cervical cancer (CC) mortality rate. MATERIAL AND METHODS: A population-based, cross-sectional study was performed in the state of Morelos, which included 3,197 women aged between 15 and 49 years, randomly selected from a household sample frame of the 33 municipalities of the state. RESULTS: Awareness of the utility of the Papanicolaou (Pap) test (OR 29.6, 95% CI 23.6-37) and a former history of gynecological symptoms (OR 1.7, 95% CI 1.2-2.4) predisposed to greater use of the DPC. Factors associated to the use of the Pap test were precedents of using one contraceptive (OR 1.4, 95% CI 1.1-1.8) or two or more contraceptives (OR 2.1, 95% CI 1.6-2.8). CONCLUSIONS: In the state of Morelos, Mexico, screening for cervical cancer is offered opportunistically in the context of health care use. Therefore, the precedent of using health care services is the main determining factor for use of the DPC program. These results reveal the need to design alternative strategies to promote participation among women who have no access to health services, since they constitute the population group at highest risk of developing CC.