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Biomedical subjects

J Vassallo

Publications and source records attributed to J Vassallo.

At least 37 records · Page 2Linked to original sources
PubMed1999

Lymphoid organ alterations enhanced by sub-lethal doses of coronaviruses in experimentally induced Trypanosoma cruzi infection in mice.

The effect of sub-lethal doses of coronaviruses on the course of disease in CBA mice experimentally infected with a mildly pathogenic strain of Trypanosoma cruzi was investigated. Mice were inoculated with either T. cruzi, 0.1 median lethal dose (LD50) of coronavirus (mouse hepatitis virus [MHV-3] or virus X), or both pathogens. Levels of parasitemia, mortality, and the extent of pathologic alterations in lymphoid organs were determined. Mice inoculated with T. cruzi had mild alterations in their lymphoid organs and survived infection. In contrast, mice inoculated with both pathogens died, and had significantly higher levels of parasitemia and profound alterations in lymphoid organs. These results indicate that the pathologic profile of T. cruzi infection can be profoundly altered by subclinical infection with coronaviruses.

Animals↗
PubMed1999

Alteration of the follicular basement membrane in non-obese diabetic mice with spontaneous autoimmune thyroiditis.

The follicular basement membrane (FBM) prevents thyroglobulin from escaping to the peri-follicular space, where it can act as an antigen to induce experimental thyroiditis. Laminin, a component of the FBM, is responsible for directing cell migration and stimulates greater adhesion of activated T lymphocytes. Our purpose was to study the expression of laminin in the thyroid of NOD mice, which have a propensity for autoimmune diseases, including thyroiditis. Thirty NOD mice between 3 and 42 weeks old were studied. Eight had thyroiditis and 22 showed no inflammatory infiltration. An immunohistochemical examination using the streptavidin-biotin-peroxidase technique was conducted on paraffin-embedded tissue sections, with a polyclonal antilaminin antibody. Antigen retrieval was achieved through pepsin digestion and microwave irradiation in citrate buffer. Staining for laminin was restricted to the basement membrane. In thyroids with no infiltration, laminin was shown as a fine, continuous brown line in the basement membrane. In 6 out of the 8 cases of thyroiditis, clearcut interruption and destruction of the FBM was observed, particularly when the follicles were located in lymphocyte infiltrated areas or when there was fibrosis. There were significant alterations in the pattern of the FBM with extensive areas of discontinuity in the distribution of laminin. Such discontinuities could facilitate antigen exposure, especially thyroglobulin, which may contribute to autoimmune thyroiditis in NOD mice.

Animals↗
PubMed1998

The value of PCNA and AgNOR staining in endoscopic biopsies of gastric mucosa.

The aim of the present study was to examine the usefulness of the quantification of PC10-positive-cells and of Argyrophilic Nucleolar Organizer Regions (AgNORs) in gastric biopsies for the identification of gastric mucosal proliferative lesions. Fifty seven paraffin-embedded endoscopic biopsies were classified into four histologic groups: normal, inflammatory, dysplastic and neoplastic mucosa. The percentage of PC10-positive cells was determined by immunohistochemistry. The AgNOR parameters determined included the total number of all identifiable silver precipitations in the nucleus, the mean number of silver precipitations per cluster, and the presence of morphologically heterogenous silver precipitations. Group comparisons were performed using the Kruskall Wallis and Dunn non-parametric tests with a significance level of 5%. A discriminant analysis (followed by the jack-knife procedure) was performed using the three AgNOR parameters plus the percentage of PCNA-positive cells as the independent variables and histological groups as the dependent variable. All three AgNOR parameters, as well as the percentage of PCNA-stained nuclei, showed their highest values in the carcinoma group. However, no good differentiation among the four histologic groups was obtained using only one of these parameters, since there was always considerable overlap among them. By combining all the parameters in a linear discriminant analysis, we obtained a correct classification in 48 out of 57 cases. Within the classification errors there was only one false positive carcinoma, which was in fact a dysplasia and only one false negative carcinoma erroneously classified as dysplasia. The number of cells with heterogenous AgNORs was the most important parameter for the discriminant analysis. No correlation between PCNA values and the AgNOR parameters could be found, thus indicating that they do not represent the same phenomenon in the cell cycle. We concluded that the use of a combination of various proliferation parameters in a linear discriminant analysis may be helpful for differentiating gastric mucosal lesions. The peculiar AgNOR morphology is an important variable which should be taken in consideration in quantitative studies. PCNA and AgNORs seem to represent different physiological phenomena in the cell cycle.

Adenocarcinoma↗
PubMed1998

Immunodepression induced by Trypanosoma cruzi and mouse hepatitis virus type 3 is associated with thymus apoptosis.

Trypanosoma cruzi-infected mice show disturbance in the peripheral immune system such as polyclonal lymphocyte activation, autoantibody production, and immunosuppression of T lymphocytes. Previous observations in our laboratory showed that some stocks of T. cruzi can be contaminated with mouse hepatitis virus type 3 (MHV-3). Literature has shown that MHV-3 infection induces immunologic disorders characterized by thymic involution with marked cell depletion. However, the effects of interactions between MHV-3 and the parasite on the immune system are not well understood. In the present study specific-pathogen-free CBA mice were inoculated with MHV-3, alone or associated with different stocks of T. cruzi. Concurrent murine virus infection resulted in increased pathogenicity of T. cruzi infection shown by profound thymic atrophy; loss of cortical thymocytes; depletion of Thy1.2+, CD4+, and CD8+ cells; enhancement of in situ labeling of nuclear DNA fragmentation; and eventually, death of the animals. Such lines of evidence show that the mechanism underlying this thymic atrophy is associated with apoptosis. These results also suggest that MHV-3 can account for the increased immunosuppression observed during experimental infection with the parasite.

Animals↗
PubMed1998

Reversal of bone marrow fibrosis in idiopathic myelofibrosis after treatment with alpha-interferon.

A 14-year-old boy presenting with primary myelofibrosis (MMM) was treated with alpha-interferon (IFN). After 6 months his spleen was no longer palpable and blood counts had returned to normal. A reversal of bone marrow fibrosis was histologically documented. Although improvement in symptoms and blood counts has been reported, this is only the second description of reversal of bone marrow fibrosis in MMM after treatment.

Adolescent↗
PubMed1996

Childhood Hodgkin's disease in Campinas, Brazil.

PURPOSE: Little clinical information about Hodgkin's disease in children is available from poor countries. The object of this study is to evaluate our data in Campinas, Brazil and hope "to make one dot on the geographic map of this disease more clear." PATIENTS AND METHODS: Between 1978 and 1988, 46 patients under the age of 17 years with biopsy-proven Hodgkin's Disease (HD) were referred for evaluation at Centro Boldrini in Campinas, São Paulo state, in Brazil. Thirty-seven of them were treated and followed-up only at this Center and are the subjects of this analysis. All the original histological slides were obtained, reviewed, and classified according to the Rye system. Staging procedures included exploratory laparotomy in 33 of 37 children, but none had lymphangiography. Treatment was individualized until January 1986 when the German protocol was adopted. RESULTS: Nineteen cases were classified as nodular sclerosis, 14 as mixed cellularity, and three as lymphocyte depleted. Mean age was 7 years; male/female ratio was 2:1. Fifty percent were advanced stages III and IV and 46% (17/37) had at least one of the systemic B symptoms. Mean follow-up was 81 months (range from 41 to 174 months). Five-year actuarial overall survival was 78%. Two children (5%) had acute myeloid leukemia at 25 and 49 months after diagnosis. CONCLUSIONS: Although distribution of histological subtypes of our cases is similar to other reports in developed countries, as well as percentage of advanced stages III/IV, our patients fared worse when compared to those reports. The reason for this continues to remain unclear but it does not seem to be related to histology subtypes.

Adolescent↗
PubMed1996

Endocervical tubal metaplasia and adenocarcinoma in situ: role of immunohistochemistry for carcinoembryonic antigen and vimentin in differential diagnosis.

Eighteen cases of endocervical tubal metaplasia (tubal metaplasia) and 16 cases of adenocarcinoma in situ were reacted immunohistochemically for carcinoembryonic antigen (CEA) and vimentin. Whereas CEA was more frequently positive in adenocarcinoma in situ cases (63%) than in tubal metaplasia cases (39%), vimentin was not expressed in adenocarcinoma but was positive in 78% of cases of tubal metaplasia.

Adenocarcinoma↗
PubMed1994

Bone marrow morphology in patients with neutropenia due to chronic exposure to organic solvents (benzene): early lesions.

The authors present the histological and cytological features of bone marrow (BM) in 152 employees from the steel plant of Cubatão (S. Paulo-Brazil) who presented with neutropenia, due to chronic exposure to benzene and its homologues. All patients were male. Mean age was 35 years. At the time of this study, all patients were removed from risk areas because of the hematological abnormality. BM morphology was characterized by a hypocellular hemopoiesis (82%). Decrease of the granulocytic precursors (86%) was the most outstanding feature. Erythroid and megakaryocytic series were diminished in 40% and 57% of the cases, respectively. Eosinophilia in BM was observed in 71% of the cases. Cell atypias and stromal changes (necrosis, increase in reticulin fibres) were frequent.

Adult↗
PubMed1994

Histiocytic necrotizing lymphadenitis in Brazil: report of a case and review of the literature.

Histiocytic necrotizing lymphadenitis is rare outside Japan, including Brazil, despite the many Japanese immigrants and descendants who live there. The authors describe the case of a 32 year old white female, who presented with cervical lymph node enlargement and severe anemia. Histological findings of the lymph node were typical for Kikuchi's disease. Bone marrow showed hyperplasia of normoblasts, suggesting hemolysis, but a Coombs' test was negative. The patient had a spontaneous resolution of all symptoms and has remained asymptomatic for 3 years. Especially where this disease is rarely reported, it is important to recognize it, in order to avoid a misdiagnosis of malignant lymphoma.

Adult↗
PubMed1994

The role of bone marrow study in diagnosis and prognosis of myelodysplastic syndrome.

In this study, cases of myelodysplasia diagnosed in a brazilian population are reported. Some differences such as a higher number of cases of hypocellular bone marrow (45.6%) were observed. There was no significant difference between patients that developed acute leukemia or not, when some bone marrow parameters such as cellularity, abnormality in reticulin fibers presence of atypically located immature precursors (ALIP), quantitative and qualitative changes of erythroblastic, granulocytic and megakaryocitic series were compared. There was no correlation either between ALIP and excess of blasts in cytology, or between FAB classification and bone marrow histology. Patients with hypocellular marrow presented lower frequency of atypic megakaryocitc than patients with normo or hypercellular bone marrow and a shorter, although not statistically significant survival. The survival of patients with ALIP was significantly lower than of those without ALIP. Cases of RAEB had a worse prognosis when compared to RA. Bone marrow histology had an important role in the differential diagnosis between MDS with hypoplastic marrow and aplastic anemia.

Adult↗
PubMed1993

Granulocytic sarcoma of the larynx preceding chronic myeloid leukemia.

The authors report one case of granulocytic sarcoma infiltrating the larynx and cervical lymph nodes in a 50-year-old smoking patient. At the time of diagnosis there was no clinical and laboratory evidence of acute myeloid leukemia or chronic myeloproliferative disease. Four months after diagnosis, bone marrow morphology was consistent with chronic myeloid leukemia, accelerated phase. Cytogenetic abnormalities (Ph 1 chromosome, t(1; 12) (p36; p13), and trisomy of chromosome 20) were also found in hemopoetic cells. Granulocytic sarcoma preceding installation of chronic myeloid leukemia, as described here, seems to be a rare clinical event.

Humans↗
PubMed1993

[Hematologic changes in patients chronically exposed to benzene].

A study was carried out into the hematological abnormalities of peripheral blood bone marrow in patients chronically exposed to benzene. The metabolic biotransformation and the mechanisms involved in toxicity are described. Hematological data are described and discussed. Macrocytosis and lymphopenia are the earliest hematological signs of benzene toxicity. Bone marrow abnormalities are demonstrated by the complementary methods of cytology and histology. Global hypocellularity was mainly due to the granulocytic series. Mastocytosis, eosinophilia and magakariocytic abnormalities are also presented. Inflammatory abnormalities and signs of dismyelopoiese could also be observed. The importance of peripheral blood abnormalities and the need for a critical approach to this important public health problem are emphasized.

Benzene↗