Analysis of the mechanical and thermal properties of jute and glass fiber as reinforcement epoxy hybrid composites.

This work describes the study to investigate and compare the mechanical and thermal properties of raw jute and glass fiber reinforced epoxy hybrid composites. To improve the mechanical properties, jute fiber was hybridized with glass fiber. Epoxy resin, jute and glass fibers were laminated in three weight ratios (69/31/0, 68/25/7 and 64/18/19) respectively to form composites. The tensile, flexural, impact, density, thermal and water absorption tests were carried out using hybrid composite samples. This study shows that the addition of jute fiber and glass fiber in epoxy, increases the density, the impact energy, the tensile strength and the flexural strength, but decreases the loss mass in function of temperature and the water absorption. Morphological analysis was carried out to observe fracture behavior and fiber pull-out of the samples using scanning electron microscope.

Immunotherapy as a treatment of American cutaneous leishmaniasis: preliminary studies in Brazil.

A prophylactic vaccine composed of killed promastigotes of five stocks of Leishmania was tested as an immunotherapeutic agent against American cutaneous leishmaniasis (ACL). The agent was administered by deep intramuscular injection daily for 10 days, followed by a 10-day interval. Out of 62 patients so treated, 47 (76%) were considered clinically cured; 41 required 2-10 treatment courses and the other six 11-19 courses. None of the patients treated by immunotherapy displayed adverse side-effects. Immunotherapy proved to be effective in the treatment of single cutaneous lesions, multiple cutaneous lesions and in cases of mucocutaneous leishmaniasis. In comparison with chemotherapy (Glucantime), immunotherapy is less efficient and more prolonged but can be safely used when antimonials are contra-indicated or are found to be ineffective. Consideration is given to the treatment of victims of ACL living in rural areas remote from a medical centre.

[Canine visceral leishmaniasis: evaluation of the serologic method used in epidemiologic studies]. / Leishmaniose visceral canina: avaliação da metodologia sorológica utilizada em inquéritos epidemiológicos.

A comparative study was made of eluates of the blood of dogs experimentally infected with different trypanosomatids. Using antigens prepared from promastigotes of Leishmania mexicana, L. braziliensis and L. chagasi, assessments were made by the indirect immunofluorescence test. The results showed a sensitivity of 87.5% in the diagnosis of canine visceral leishmaniasis, independent of antigen used. Cross-reactions occurred in 75% of cases of cutaneous leishmaniasis and 83.3% of dogs with chagas' disease. An epidemiological survey in an area of leishmaniasis confirmed that immunofluorescence tests on eluates of dogs' blood give cross-reactions between L. braziliensis and L. chagasi. The results suggest that such testing could be useful in public health campaigns but attention is drawn to the fact that the level of positive reactions cannot be used as an indicator of the prevalence of canine kala-azar.

Histological observations on Montenegro's reaction in man.

The Montenegro skin test is widely used as a diagnostic method for American cutaneous leishmaniasis (ACL) but little is known about the histological changes that occur in the skin after administration of the antigen. This report is based on histological studies of biopsied material obtained, from inoculation sites, 48 hours after individuals had been given intradermal injections with a standardized Montenegro antigen. The material examined was obtained from four distinctly different test groups: naturally infected patients with parasitologically proved ACL and with positive Montenegro's reaction; individuals without previous history of ACL and not previously tested with Montenegro antigen; participants in anti-ACL vaccine trials who developed positive reactions to Montenegro antigen after vaccination; other participants in vaccine trials who had negative Montenegro responses after vaccination or had served as controls in the trials. The histological pictures of each group are described and discussed. Histologically, the reactions of vaccinated individuals were indistinguishable from those with naturally acquired infections.

The change of behavior of two strains of Leishmania after cultivation in a defined medium

Duas cepas de Leishmania originalmente isoladas in vitro de casos humanos de leishmaniose cutânea e que ab initio näo infectaram animais de laboratório, tornaram-se infectantes para hamnsters após serem mantidos por vários anos em meio de cultura quimicamente definido. Foram realizadas observaçöes sobre o crescimento de promastigotas in vitro, curso da infecçäo em hamsters, morfologia das amastigotas, mobilidade eletroforética de oito enzimas solúveis. Foram obtidas informaçöes sobre a densidade de flutuaçäo do n-DNA e do k-DNA e uma das cepas foi testada contra anticorpos monoclonais. Ambas as cepas permanecem sem identificaçäo precisa

The change of behaviour of two strains of Leishmania after cultivation in a defined medium.

Attempts have been made to characterize two strains of Leishmania that became infective to golden hamsters only after they had been maintained for several years in a chemically defined culture medium. Observations were made on the growth rates of promastigotes in vitro, course of infection in hamsters, morphology of amastigotes, and electrophoretic mobility patterns of eight isoenzymes. Information was obtained about the buoyant densities of n-DNA and k-DNA, and one strain was tested against monoclonal antibodies. The identity of both strains remains obscure.

Controlled field trials of a vaccine against New World cutaneous leishmaniasis.

Two controlled, double blind field trials of a non-living promastigote vaccine against New World Cutaneous Leishmaniasis (NWCL) were conducted in 1981 and 1983 in Brazil. Brazilian Army conscripts were randomly assigned to the vaccine or placebo groups and tested during their training in the Amazon jungle, a high risk area for NWCL. The results obtained showed: no significant differences between the vaccine and the placebo groups with respect to a number of characteristics (age, race, previous contact with the jungle, etc.); no significant differences between the participants who got and who did not get NWCL during the trial, with respect to length of exposure, contact with the jungle, etc. and a reduction of 67.3 and 85.7% in the annual incidence rate of NWCL, in 1981 and 1983 respectively (although the difference between incidence rates of the disease in vaccinated and control groups in the 1983 trial was not statistically significant), among those vaccinated who had converted to a positive leishmanin skin test as compared with the placebo groups.

An experimental vaccine against American dermal leishmaniasis: experience in the State of Espírito Santo, Brazil.

A vaccine prepared from killed and sonicated promastigotes of five Brazilian strains of Leishmania was used during an epidemic of American dermal leishmaniasis that occurred in Viana county, State of Espírito Santo, Brazil. Initially, all of the participants in the vaccination programme had negative reactions to Montenegro antigen. Forty days after the last dose of vaccine had been given, 87.6% of the 216 vaccinated individuals had become Montenegro-positive whereas the 266 unvaccinated persons remained Montenegro-negative. The study area had an unstable population and details are given about the human population changes that occurred during the two-year study period. Taking into account population movements, 1.5% of those vaccinated and 6.4% of the unvaccinated group developed dermal leishmanial lesions by the end of the first year. At the end of the second year, 1.7% of those vaccinated and 8.9% of the unvaccinated group had become infected. The difference in infection rates of the two groups is statistically significant at both the end of the first and second years of observation. Diagnosis of the disease(s) was based on the clinical appearance of lesions combined with parasitological and/or immunological evidence and subsequent responses to treatment. The experience gained in Viana also provided information about the storage and administration of the experimental vaccine which have been used in mounting a randomized clinical trial.

American cutaneous leishmaniasis: disappearance of amastigotes from lesions during antimonial therapy.

Durante o tratamento com antimonial de Nmetil glucamina (Glucantime) dez pacientes com forma cutanea de leishmaniose tegumentar americana foram observados, para se determinar o tempo de desaparecimento de amastigotas das lesoes. Antes do tratamento todos os pacientes apresentavam teste de Montenegro positivo e amastigotas em esfregacos realizados por aposicao de material biopsiado das lesoes. O isolamento de parasitos da lesao em meio de NNN foi positivo em sete pacientes e em oito os cortes histologicos mostraram presenca de amastigotas. Durante as 10 primeiras doses de glucantime todos os pacientes tiveram culturas negativas. Amastigotas foram detectadas em esfregacos por aposicao ate a quarta dose e nos cortes histologicos ate a sexta dose de Glucantime. Os aspectos histopatologicos antes do tratamento sao brevemente descritos. Em apenas 2 pacientes observou-se durante o tratamento modificacoes histopatologicos dignas de nota: com o aparecimento de fibrose extensiva e hiperplasia pseudo carcinomatosa estes casos como os demais evoluiram para a cicatrizacao e cura das lesoes. Em vista dos resultados obtidos, os Autores concluem que a cura clinica das lesoes, pelo menos nas formas de leishmanioses cutaneas no Vale do Rio Doce, e ainda o melhor criterio para interromper o tratamento com antimoniato de N-metil glucamina, no esquema de tratamento utilizado no presente trabalho

Epidemiology of dermal leishmaniasis in the Rio Doce Valley, State of Minas Gerais, Brazil.

Dermal leishmaniasis is prevalent in the predominantly settled agricultural areas in the Rio Doce Valley in the eastern part of the State of Minas Gerais, Brazil. The disease has been recorded almost equally in both sexes. Cases have been confirmed in all age groups but youths aged ten to 14 years form the population segment at greatest risk to infection. Cases of single cutaneous lesions, multiple cutaneous lesions and muco-cutaneous lesions have been recorded in the area. Isolates of parasites include representatives of the Leishmania mexicana and L. braziliensis complexes and at least one parasite that does not fit into either category. Infections have not been detected in small mammals (mainly rodents) but about 3% of dogs are infected. The phlebotomine fauna includes no species (or close relatives of species) previously incriminated as vectors of mexicana and braziliensis infections in Brazil. In the complex and confusing epidemiological situation in the Rio Doce Valley it seems unwise to apply traditional specific names to Leishmania of the area.

A field trial of a vaccine against American dermal leishmaniasis.

A field trial was carried out in the eastern part of the State of Minas Gerais (Brazil) of a vaccine containing killed promastigotes of five stocks of Leishmania. Tests with Montenegro antigen showed that a high proportion of the vaccinated persons became positive within three months, but circulating antibodies were not detected. A proportion of those vaccinated continued to give positive Montenegro reactions for up to three years. Lymphocyte sensitivity tests carried out, on a small sample, three years after vaccination were positive and gave no evidence of immunological depression. No cases of cutaneous or mucocutaneous leishmaniasis occurred in the trial area during the three years of observations.

Mastomys natalensis as an experimental host for Leishmania mexicana mexicana.

Young multimammate rats (Mastomys natalensis) can be readily infected when inoculated intradermally with the amastigotes of Leishmania mexicana mexicana. Lesions appear at the site of inoculation in the second week of infection and continue to increase in size for the first month; amastigotes can be detected during this period. In the second month, lesions begin to decrease in size and it is more difficult to detect amastigotes. Three months after inoculation, the rats show no sign of infection. The results suggest that M. natalensis could be a useful laboratory host for immunological studies on dermatotropic Leishmania and for chemotherapeutic assays.