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Biomedical subjects

A Prata

Publications and source records attributed to A Prata.

18 recordsLinked to original sources
PubMed1992

Influence of the host related factors in the development of the hepatosplenic form of schistosomiasis mansoni.

The frequency of hepatosplenomegaly in endemic areas is not proportional to the fecal ova count. This may be explained by epidemiological genetic. The occurrence of two or more cases of schistosomal hepatosplenomegaly in nuclear family is much higher than expected. The concentration is higher among siblings than it is among mothers and children of father and children. It is not significant between father and mother. If the mother, instead of the father, has hepatosplenic schistosomiasis the relative risk for the child to acquire hepatosplenomegaly is at least five times (the maternal affect). The inbreeding is higher in the hepatosplenic than in the hepato-intestinal patients. In some areas in Brazil the hepatosplenic form of the schistosomiasis mansoni occurs with much higher frequency in whites than in blacks. After treatment, reversion of hepatosplenic schistosomiasis occurs more frequently in non-whites. It seems that the resistance of blacks to the hepatosplenic form of schistosomiasis may be related to the glyoxalase system, perhaps associated to another genetic marker. The hepatosplenic schistosomiasis is less frequent in longilineal individuals. In some areas the hepatosplenic form of schistosomiasis is more frequent in A blood group of ABO system. The family heredograms do not suggest a single mendelian inheritance, but probably a multifactorial and possibly polygenic one.

ABO Blood-Group System↗
PubMed1992

Phagocytic and bactericidal function of mouse macrophages to Salmonella typhimurium in schistosomiasis mansoni.

Patients infected with schistosomes may develop a clinical picture of chronic salmonellosis. We have investigated the altered function of macrophages capable of playing a role in the development of chronic salmonellosis associated with Schistosoma mansoni in an experimental model. The capacity of mouse peritoneal macrophages to ingest and kill Salmonella was assessed in mice infected with S. mansoni with or without concurrent Salmonella typhimurium infection. Schistosomiasis was associated with a significant decrease in the phagocytic index of macrophages, due to the reduced number of cells engaged in phagocytosis. However, the number of bacteria ingested by these cells was comparable to that of the control group. The bactericidal capacity of macrophages from S. mansoni-infected mice was also significantly lower than that of cells from normal mice. Macrophages from animals infected only with Salmonella typhimurium showed an increased phagocytic capacity. It was concluded that S. mansoni infection alters phagocytosis and intracellular destruction of salmonellae. This demonstration of a novel mechanism of survival of salmonellae represents a step forward in understanding the pathogenesis and management of chronic septicemic salmonellosis.

Analysis of Variance↗
PubMed1978

Acquired cell-mediated immunodepression in acute Chagas' disease.

In this study two groups of patients with acute Chagas' disease were identified. Group one consisted of five patients with apparent acute Chagas' disease. These patients showed symptoms and signals of an acute illness, such as high fever and enlarged spleen. One of these patients developed severe myocarditis and heart failure. Group two consisted of seven patients with inapparent acute Chagas' disease. This was a nonclinical entity, not perceived by the patient who did not seek medical care. The diagnosis was made by the shift of a serologic test which indicates the presence of immunoglobulin M antibodies to Trypanosoma cruzi. The patients with apparent acute Chagas' disease showed positive delayed-type skin response to T. cruzi antigen. Also, their leukocytes showed significant inhibition of migration in the presence of this antigen. By contrast, the patients with the inapparent acute Chagas' disease did not show positive delayed-type skin response to T. cruzi antigen and no significant inhibition was observed when their cells migrated in the presence of this antigen. Of interest, none of these patients was capable of developing contact sensitivity to 2,4-dinitrochlorobenzene. However, three out of five patients with the apparent acute disease and all the normal control subjects showed positive contact reaction after sensitization to this drug. The results of these experiments would suggest that the thymus-derived (T)-lymphocyte function is depressed in patients with the clinically inapparent acute Chagas' disease. This immunodepression seems to be acquired in the course of the T. cruzi infection because all patients showed positive delayed-type skin response to at least one ubiquitous microbial extract, thus indicating previously normal T-cell function. We hypothesize that T. cruzi antigens may directly stimulate T cells with the concomitant release of factors that might become supressive for T-cell responses. Furthermore, the suppressive effect might interfere with the T-cell response to other antigens, such as to 2,4-dinitrochlorobenzene.

Acute Disease↗
PubMed1978

Trypanosoma cruzi-sensitized T-lymphocyte mediated 51CR release from human heart cells in Chagas' disease.

Cytotoxicity of T-lymphocytes from patients with Chagas' disease to parasitized and non-parasitized human heart cells labelled with 51Cr was demonstrated. The highest ratio of 51Cr released from the normal, non-parasitized heart cells was observed when the T-lymphocytes were collected from patients with acute Chagas' disease. The quantity of 51Cr released from the normal heart cells that were destroyed by T-lymphocytes collected from patients with chronic Chagas' disease was also significantly higher than the quantity of 51Cr released from normal heart cells incubated with lymphocytes from normal donors. The specific release of 51Cr from the heart cell cultures destroyed by the immune T-lymphocytes from patients with acute Chagas' disease and from patients with chronic disease was 38.1% and 25.8%, respectively, compared to the release of 51Cr observed in control studies. A small particle human heart cell antigen was shown to inhibit the migration of Trypanosoma cruzi-immune peripheral blood leukocytes. The findings appear to indicate that T-lymphocytes from patients with Chagas' disease are susceptible to activation by a cross-reactive heart cell antigen and suggest that an autoimmune mechanism can be established in some cases of acute Chagas' disease and can be perpetuated in the chronic phase of this disease by the continuous antigenic stimulation. Further, these experimental data indicate that the autoimmune destruction of heart cells in Chagas' disease is produced by delayed-type hypersensitivity mediated by T. cruzi-sensitized T-lymphocytes.

Autoantibodies↗
PubMed1977

Immunological studies in human schistosomiasis. III. Immunoglobulin levels, antibodies, and delayed hypersensitivity.

Levels of IgG, IgE, IgM, and IgA were determined, specific antibodies were detected by the fluorescent antibody test, hemagglutination test, complement fixation test and immunoelectrophoresis, and intradermal tests for delayed hypersensitivity to Schistosoma mansoni antigens were performed in Brazilian patients with schistosomiasis mansoni. The results were compared according to the clinical forms of the disease. IgG levels and antibody titers increased progressively in the subclinical, hepatomegalic, and hepatosplenic forms and there was a statistical relationship between IgG levels and the intensity of responses to the four serological tests; Delayed hypersensitivity (DHS) was found more frequently in hepatosplenic patients and more particularly in those with splenomegaly. DHS also correlated with age, but not with sex or with skin color. The strongest DHS reactions were observed in patients 20 to 34 years old, and in those having the highest fecal egg output. IgG levels, antibody titers, and DHS responses decreased after splenectomy and portal filtration of the worms. No significant variation was observed between untreated subjects, patients who were splenectomized and a group not subject to reinfection for 4 yearsk0

Antibodies↗
PubMed1976

Sensitization to Schistosoma mansoni antigen in uninfected children born to infected mothers.

Sensitization to Schistosoma mansoni antigen in uninfected children born to infected or uninfected mothers was studied by intradermal reaction. Immediate skin reaction, Arthus phenomenon, and delayed skin responses were noted. The skin response at 24 hr was positive in 48.1% of the uninfected children born to infected mothers, and in only 7.5% of uninfected (control) children born to uninfected mothers. Areas of skin reactions were also larger in the group born to infected mothers. Both of these differences were statistically significant. There were no significant variations according to age or sex. Only one immediate skin reaction was noted in each group, and Arthus phenomenon was never observed.

Antigens↗
PubMedDate not supplied

Fulminant hepatitis with microvesicular steatosis (a histologic comparison of cases occurring in Brazil--Labrea hepatitis--and in central Africa--Bangui hepatitis).

A similar histopathologic picture of fatal hepatitis associated with widespread acute fatty changes in hepatocytes and single-cell necrosis was seen in epidemic cases occurring in two distinct equatorial areas having high prevalences of HBV and HDV infections. The cases were previously considered to be two different entities; Labrea hepatitis in Brazil, and Bangui hepatitis in the Central African Republic. However, the histopathologic findings suggest that they are pathogenetically and etiologically related to HBV and HDV infections, probably modified by some as yet unknown factor(s) present in equatorial forest zones.

Adolescent↗
PubMedDate not supplied

[A longitudinal radiologic study of the esophagus in an endemic area of Chagas' disease over a 6-year period].

A longitudinal study over six years was undertaken of 494 residents of the municipality of Mambaí, Goiás. Two hundred and twelve (43%) were seropositive in 1975/76 and 199 of 464 of the same patients group, positive in 1980/82 (42.8%). At both examination single radiographs of the oesophagus were obtained immediately after ingestion of 75 ml of barium sulphate solution and a second X-ray taken one minute later. Among the 201 seropositive patients without megaesophagus in the first study 4 (2%) evolved megaesophagus during the six years of observation. During this time, using Rezende's classification, patients with established megaesophagus, changed their group in the following manner. Only one Group I patient changed to group II. Only one group II patient progressed to group IV. Progress of megaesophagus in the affected patients occurred in 2.8% of 212 patients. Also four patients with grade I megaesophagus initially had a normal oesophagogram on the follow up examination. Ten patients had doubtful oesophagogram initially and six on follow up, 75% of these patients were seropositive. This study could indicate that a doubtful oesophagogram is an early sign of megaoesophagus.

Adult↗