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Biomedical subjects

M Lorca

Publications and source records attributed to M Lorca.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Application of a system of serological surveillance of Chagas disease in a region of high chagasic endemia. I. Prevalence of Trypanosoma cruzi infection in Salamanca].

A serologic study for prevalence of Chagas infection was performed in Salamanca, Northern Chile. Indirect immunofluorescence and indirect hemagglutination reactions were used in samples from 1529 females and 698 males representing 10% of the population. A total of 499 positive results were obtained. The incidence of infection increases at a mean rate of 1% per year up to age 30, declining slowly in older groups to reach a maximum of 39.7% for the population. These data will be used to implement appropriate serologic surveillance programs and sanitary control measures in this and other populations.

Adolescent↗
PubMed1990

Trypanosoma cruzi: a possible control of transfusion-induced Chagas' disease by phenolic antioxidants.

The following phenolic antioxidant food additives were evaluated against Trypanosoma cruzi epimastigotes: BHT, BHA, gallic acid and its methyl, propyl, octyl, and lauryl esters, 2,4-di-tert-butyl-6-(4-methoxybenzyl)-phenol, 4,4'-isopropilidenediphenol, and protocatechuic acid and its ethyl ester. The inhibition of the respiration; the changes in motility, shape, and lysis of the parasites; and the human blood hemolysis caused by these chemicals were studied. Human blood samples experimentally contaminated with 2000 or 150,000 trypomastigotes per milliliter were freed of parasites after treatment for 24 hr at 4 degrees C with 5 or 10 mM BHT (2,6-di-tert-butyl-4-hydroxytoluene), respectively. Consequently, BHT and other phenolic compounds deserve further study to determine their role in preventing the transmission of Chagas' disease by blood transfusion.

Animals↗
PubMed1990

Fetal IgG specificities against Trypanosoma cruzi antigens in infected newborns.

A panel of Trypanosoma cruzi antigens produced by recombinant DNA techniques was used to analyze the IgM and IgG specificities present in sera from 22 mothers with chronic Chagas disease and their newborn infants. Ten of the newborns were congenitally infected and the other 12 children were healthy. While in most cases IgG specificities in the newborns mirrored those of their mothers, congenitally infected newborns had, in addition, IgG specificities that were undetectable in their mothers. The new IgG specificities observed most frequently were against a shed acute-phase antigen (SAPA), and less frequently, against other nine different parasite antigens. Thus, SAPA is able to identify new fetal IgGs because antibodies against this antigen are generated during the acute phase of the infection and not in their chronically infected mothers. Sera from congenital cases also had IgMs against several parasite antigens, but again, SAPA was the most frequently detected. Neither IgMs nor new IgG specificities were detected in healthy children born to mothers with Chagas disease. We conclude that individual antigens can be used to detect new IgG specificities present in the cord blood from infected newborns. Furthermore, detection of IgMs and new fetal IgGs with recombinant antigens may be used to sort out congenitally infected infants from uninfected ones, a method that might be applied to other infectious diseases.

Animals↗
PubMed1989

[Chagas' disease in patients in chronic hemodialysis. Prevalence and risk of transmission by blood transfusion].

A serologic study of Chagas disease was performed in 110 patients submitted to chronic hemodialisis and blood transfusions. Immunofluorescence antibody testing (IgG and IgM) was positive in 6 out of 62 patients receiving multiple blood transfusions (9.7%), but negative in all 48 subjects without transfusions. Thus, repeated blood transfusion is a significant risk for T cruzi infection in chronic hemodialized patients.

Chagas Disease↗
PubMed1989

Hydatidosis diagnosis by double diffusion in agar with arc 5 detection.

To further assess the double diffusion arc 5 (DD5) test for human hydatidosis, the test was performed on sera from 45 patients with surgically confirmed hydatidosis and 54 with other pathologies in Santiago, Chile. Combined with tests reported previously, this brought the total number of study subjects with confirmed hydatidosis to 98 and the total with other pathologies to 128. Overall, the test yielded positive results with sera from 55 (56%) of the 98 serologically confirmed cases, the degree of seropositivity among patients with pulmonary hydatidosis (36%) being relatively low. The criteria adopted for a positive result were the presence of arc 5 or, in the absence of arc 5, the presence of three or more bands of precipitate. On the basis of these criteria, no false positive results were detected using sera from the 128 patients with other pathologies. It is concluded that using the DD5 test to diagnose hydatidosis in clinically selected individuals can provide results of high specificity; i.e., positive results can be taken as confirming presence of the infection. On the other hand, a negative DD5 result does not constitute definite proof that no hydatid cysts are present.

Adolescent↗
PubMed1978

A comparative study of some combined treatment regimens in acute toxoplasmosis in mice.

The effectiveness of five treatment regimens was compared to mice during acute and late infection with Toxoplasma gondii. Parasitic cure rates, as judged by failure of brain tissue from surviving mice to produce infection when inoculated into clean mice, were as follows: pyrimethamine + sulfamethoxypyridazine, 92%; clindamycin + sulfamethoxypyridazine, 75%; spiramycin + sulfamethoxypyridazine, 16.7%; trimethoprim + sulfamethoxypryridazine alone, 0%. Pyrimethamine + sulfamethoxypyridazine was the most effective combination against acute toxoplasmosis in mice.

Acute Disease↗
PubMedDate not supplied

Identification of immunodominant antigens by immunoelectrotransfer in hydatid fluid.

Identification and characterization of immunodominant antigens in hydatid fluid was performed by electrophoresis in polyacrylamide gels (SDS PAGE) followed by immunoelectrotransfer (Western Blot). The studies were performed in sera of 23 patients with surgically confirmed hydatid disease, 12 patients with clinical suspicion of the infection and positive serology according to conventional serology (double diffusion with detection of are 5 and ELISA test), 28 healthy subject and 23 patients with parasitic infections different from hydatidosis. The results showed 7 antigenic bands located between 8 and 120 kDa, two immunodominant bands (MW 8 and 12 kDa) were recognized by the sera of patients suffering from hydatid disease and those with positive serology. Two additional bands were detected by the sera of healthy subjects and by the samples of patients presenting cysticercosis. It is concluded that the antigens with molecular weights of 8 and 12 kDa. would be those of major diagnostic value, while those of 32 and 60 kDa are nonspecific.

Antigens, Helminth↗
PubMedDate not supplied

[Epidemiological status of Chagas disease in the endemic area from Region II of Antofagasta].

During 1997 a seroepidemiological study on Chagas' disease was carried out in 18 localities of three provinces (Tocopilla, El Loa and Antofagasta) of Region II (20 degrees 56'-26 degrees South Lat.; 70 degrees 38'-67 degrees West Long.), in order to assess the impact of the control program against Triatoma infestans launched in 1988, based on insecticide spraying of dwellings. By means of ELISA and an indirect hemagglutination test for Chagas' disease blood samples from 1,034 children under 10 years of age were examined, arising a 0.5% (3 cases) positivity. Test resulted positive in 2 (0.9%) children from the locality of San Pedro de Atacama and 1 (0.4%) from Calama city, all in the age group 6-10 year-old. However, none of their dwellings were found infested with T. infestants. These results indicate that the control program has a good possibility to prevent new human infections. It is advisable to continue the seroepidemiological and entomological vigilance and remark the necessity of increasing the effort in the study of transmission through other routes, to adopt or reinforce the pertinent preventive measures.

Adult↗
PubMedDate not supplied

[Frequency of anti-Toxoplasma gondii antibodies in cats from Valdivia city, Chile].

Toxoplasmosis is a parasitic zoonosis. The importance of the cat as related to this parasitosis lies in the fact that it is not only the definite host of the parasite, but responsible for its dissemination through the release of oocysts, which subsequently infect both humans and other animals. The objective of this study was to determine the serological prevalence of Toxoplasma gondii in the feline population of the city of Valdivia (Chile) and to establish the possible epidemiological implications of this prevalence. With these goals in mind the technique of indirect immunofluorescence was implemented to detect anti- T. gondii species--specific IgG. Blood samples from 97 cats (selected using a directed sampling process) from different sectors of Valdivia were collected. The sample included 46 males and 51 females of different ages, Positive and negative control sera obtained from de United States were used to verify the results, observed by UV microscopy. The anti-feline IgG antibody was used as directed by the manufacturer (Sigma). Of the 97 selected cats, 32 were found to be positive with a titre higher than 1:4, a prevalence of 33.0%. The number of infected males as compared to the number of infected females was found to be statistically insignificant, using the chi-square analysis with p less than 0.1. In contrast, a definite correlation between age and seropositivity was found; infection levels were higher in older animals. These results are consistent with those obtained in different studies on this topic that have been performed in different parts of the world. However, they would seem to be in conflict with other, similar studies that have been done recently in Chile; this may be due to the fact that the cats selected for this study were exposed to different climatic conditions than those examined in previous works. In conclusion, it has been determined that in Valdivia exist cats infected by T. gondii, which indicate the presence of the necessary epidemiological conditions for the persistence of this parasitic cycle and the source of infection for humans and other animals.

Animals↗
PubMedDate not supplied

[Comparison of Trypanosoma cruzi infection in less than 10 years old children from the V Región, Chile, 1982-1995].

Evaluation of desinsectation programs carried out in the two Health Services from the V Region, was undertaken by comparing serologic prevalences of T. cruzi infection age groups exposed to the risk of infection in rural areas during the antivectorial campaign activities (1982 vs 1995). Thus, were studied 2,193 blood samples from children under 10 years of age, proceeding from six chagasic endemic provinces in which antitriatomic domiciliary insecticide sprayings had been performed. Indirect hemagglutination and ELISA tests were carried out to each of the blood samples. A total de 42 (1.9%) children resulted positive. As in five counties no positive cases were detected in the last five years it is possible to assume that vector transmission of T. cruzi should have been interrupted in them. When comparing prevalences existing in 1982 with the present ones, it is possible to observe a 63.5% of reduction of transmission in the V Region, been this reduction higher in the Aconcagua Health Service with 79.6% and lower in the Viña del Mar--Quillota Health Service with 55.6%. According to these results, comparison of prevalence of T. cruzi infection in children less than 10-year-old in diverse periods, allows evaluate the vectorial control of Triatoma infestans programs.

Animals↗
PubMedDate not supplied

[Serological diagnosis of congenital infection with Trypanosoma cruzi].

Enzyme linked immuno sorbent assay (ELISA) for IgG and IgM antibodies against T. cruzi were applied to 382 sera form adults and newborn infants, referred to our laboratory for serological diagnosis, to improve diagnosis of congenital Chagas disease. A comparative study between immunofluorescent antibody test (IFAT) and ELISA results was undertaken for IgG T. cruzi antibodies in 346 samples of adults sera, 225 of which were IFAT negative (non reactive or reactive at dilutions under 1/10) and 121 IFAT IgG positive (reactive at dilutions > or = 1/20). Positive results were obtained with both methods in 117 patients, only with ELISA in 11 IFAT negative samples and only with IFAT at low titers in four ELISA IgG negative (non reactive or reactive in dilutions < or = 1/40) samples. Thus ELISA IgG did not detect more infections than IFAT IgG, although ELISA showed higher titers (> or = 2 dilutions) in 42/117 simultaneously positive specimens. In 88 sera from patients with acute, chronic and initial infection, ELISA-IgM rendered more positive results than IFAT-IgM, including approximately 17% of low titers false positives in control's sera. For this reason, when such results are obtained in patient's sera, it is advisable to consider them suspicious and to repeat the test in order to get a definitive result. ELISA allowed to detect IgM in sera from four of 36 infants born to infected mothers, which had given negative results with IFAT IgM. These results confirm that ELISA is more sensitive than IFAT for IgM antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗