Browsing by Author "Tapia, A"

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    First-trimester pregnancy loss and active Chlamydia trachomatis infection
    (2002) Vigil, P; Tapia, A; Zacharias, S; Riquelme, R; Salgado, AM; Varleta, J
    The incidence of Chlamydia trachomatis (Ct) infection and the possible correlation between couples presenting with first-trimester spontaneous abortions and active Ct infection was assessed. Additionally, the ability of Ct to infect zona-free hamster oocytes was explored by incubating the oocytes with spermatozoa from infected patients. A total of 961 women and 750 men consulting our reproductive medicine centre were screened for Ct using direct immunofluorescence. The general incidence of Ct infection was 9.4% in females ( 90 of 961) and 13.9% in males ( 104 of 750). In women with spontaneous abortions the incidence of Ct was 21.0% ( 14 of 66) compared with 8.9% ( 23 of 59) for women without spontaneous abortions and term pregnancies (chi-square, P < 0.05). When both partners of the couples were considered ( one or both partners infected), the incidence rose to 68.8% ( 22 of 32) (chi-square, P < 0.001). In vitro studies using electron microscopy demonstrated the presence of Ct on the surface of and inside the oocyte. These results indicate a correlation between an active Ct infection and spontaneous abortion. Electron microscopy studies suggested the possibility of direct oocyte infection by Ct. Two models are proposed for the pathogenesis of Ct-related early abortions: ( i) direct zygote infection, and (ii) immune response to heat shock proteins expressed by the zygote and triggered by previous Ct infections.
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    Chlamydia trachomatis infection in male partners of infertile couples
    (2002) Vigil, P; Morales, P; Tapia, A; Riquelme, R; Salgado, AN
    Chlamydia trachomatis infection is one of the most common sexually transmitted diseases. Its effect on male fertility, however, is still controversial. In this study, 284 male partners of infertile couples consulting the Center of Studies in Reproductive Biology (CEBRE) were analyzed. The incidence of C. trachomatis infection among male partners of infertile couples was 38.6%. There were no significant differences between infected and noninfected infertile men in any of the sperm parameters assessed (sperm concentration. motility and morphology). The results of the three bioassays developed to evaluate sperm physiology, namely spermatozoazona pellucida binding. acrosome reaction stimulated with human follicular fluid and zona-free hamster oocyte penetration, showed no differences between infected and noninfected men. Electron microscopy studies suggest that spermatozoa are active agents in the dissemination of the chlamydial infection; they could be acting as 'vehicles' for the pathogens. These, and other results. suggest that the possible effect of C. trachomatis on male fertility is not due to alterations in sperm 'quality' or function, but rather to the transmission of the disease to female partners, causing inflammatory processes and promoting the generation of antisperm antibodies.
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    In vitro regeneration of Sophora toromiro from seedling explants
    (2001) Jordan, M; Larrain, M; Tapia, A; Roveraro, C
    Embryonic axes with cotyledons, shoot-tips of embryonic axes, isolated cotyledons, as well as axillary buds and leaves from 20-year-old trees of Sophora toromiro, were evaluated for their capacity to trigger organogenesis and to regenerate plantlets under in vitro conditions. Embryonic shoot-tips were the only explants capable of regenerating plants. They developed rapidly in vitro in the presence of NAA and BA while in subculture roots were induced at the proximal end in the presence of 0.49 muM IBA within 40-60 days. Development was completed with a subculture phase under non-sterile conditions using a mixture of equal parts of sterilized vermiculite/sand/soil in growth chambers, before final acclimation in the greenhouse. In the presence of NAA, BA and GA(3), whole embryonic axes formed multiple shoots that branched when grown in 2.27 or 11.35 muM TDZ in subculture. Similarly, callus was initiated at the embryo axis base, developing into several new shoots in the presence of TDZ. Because of the relatively high shoot induction rate along the embryonic axis, this axis presents a valuable source of new juvenile explants. Growth and rhizogenesis was satisfactory only when organs from seed pods of the year or from the previous season were used. Experiments with isolated cotyledons produced callus only, while axillary buds and leaves did not show any responses in the presence of several growth regulators assayed. Inoculation of seedlings with various strains of rhizobia under in vitro conditions resulted in root outgrowths, but not in nodules that are typical of rhizobia infection.