The paraflagellar rod proteins (PAR) purified from Trypanosoma cruzi epimastigotes were shown to protect mice against an otherwise lethal challenge inoculum of 10 3 bloodstream-form trypomastigotes. The injection route used for immunization was shown to have a marked impact on the development of protective immunity. Mice receiving subcutaneous (s.c.) injections of PAR proteins had reduced bloodstream parasitemias and showed 100% survival following challenge. In contrast, mice immunized via the intraperitoneal (i.p.) route developed parasitemia levels equivalent to those of unimmunized controls and did not survive infection. Western blotting (immunoblotting) demonstrated that sera from both i.p. and s.c. immunized mice reacted specifically with PAR proteins; however, the antibody titer of the i.p. immunized mice was approximately 64-fold greater than that of the s.c. immunized mice, suggesting that the protective response in the s.c. immunized mice is cell mediated rather than humoral.Trypanosoma cruzi is a parasitic hemoflagellate that causes Chagas' disease, a major human health problem in Central and South America (4). Chemotherapeutic agents have limited effectiveness against the disease, and no vaccines are available for disease prevention. Experimental vaccines consisting of attenuated forms of the parasite, crude parasite lysates, partially purified proteins, and synthetic peptides derived from the sequence of a 24-kDa excretory protein (ESA) have been tested in laboratory animals with varying degrees of success (reviewed in references 2, 5, 7, 16, and 22). Several of these studies show that susceptible hosts may be partially protected against death by vaccination prior to challenge; however, individual antigens capable of ensuring survival against an otherwise lethal challenge have yet to be identified.In an attempt to identify and purify protective antigens, we focused on proteins present in the flagellum of T. cruzi. The rationale for this approach is based on studies demonstrating that vaccination with crude flagellar extracts are effective in both inducing protective immunity (i.e., 90% survival) in mice after challenge (15,20,21) and reducing tissue lesions in immunized mice compared with nonimmunized mice following a challenge infection (14). In contrast, immunization with a membrane-enriched fraction from the body of the parasite was less effective in inducing a protective response, suggesting that the protective antigen(s) may be unique to the flagellum. A potential candidate for such antigens is the paraflagellar rod, a prominent structure present only in the flagellum of the parasite (5). We have shown that the paraflagellar rod contains two distinct proteins, PAR 1 and PAR 2, and have determined conditions that allow these proteins to be isolated in amounts and purity sufficient for immunization trials (3,18).In this paper, we report the ability of the purified PAR proteins to induce an immune response in mice capable of protecting against an otherwise lethal inoculum of T. cruzi trypomastigote...
Missed appointments are a problem in all types of outpatient clinics including those providing mental health care. A review of literature was conducted to explore the problem of missed appointments in mental health and identify methods that have been used to improve attendance. Study results demonstrate that patients miss appointments for many reasons. Common reasons for missed appointments in the articles reviewed were the interval between scheduling and appointment day, forgetting, being discharged against medical advice, and problems with substance abuse. Effective in reducing no shows was contact via phone, mail, or text messaging. No articles were found related to the use of positive reinforcement in reducing no shows, which is an area to consider for further research. Clinicians may identify techniques from this review applicable to their particular clinical setting to improve clinic attendance.
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