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Biomedical subjects

C L Silva

Publications and source records attributed to C L Silva.

9 recordsLinked to original sources
PubMed1992

Detection of cellular immunity with the soluble antigen of the fungus Sporothrix schenckii in the systemic form of the disease.

Sporothrix schenckii is the etiologic agent of sporotrichosis, a mycosis of world-wide distribution more commonly occurring in tropical regions. The immunological mechanisms involved in the prevention and control of sporotrichosis are not fully understood but apparently include both the humoral and cellular responses. In the present investigation, cellular immunity was evaluated by in vivo and in vitro tests in mice infected with yeast-like forms of S. schenckii. The disease developed systemically and cellular immunity was evaluated for a period of 10 weeks. The soluble antigen utilized in the tests was prepared from yeast form of the fungus through the sonication (20 min: 10 sonications at 50 W at 2-min intervals). Delayed hypersensitivity and lymphocyte transformation tests showed that the cellular immune response was depressed between the 4th and 6th week of infection when the animals were challenged with the soluble fungal antigen. This depression frequently indicates worsening of the disease, with greater involvement of the host. This is a promising field of research for a better understanding of the pathogeny of this mycosis.

Animals↗
PubMed1992

Mycobacterium leprae 65hsp antigen expressed from a retroviral vector in a macrophage cell line is presented to T cells in association with MHC class II in addition to MHC class I.

Mycobacterium leprae lives free in the cytoplasm in infected macrophages. To test if an M. leprae antigen released into the cytoplasm would associate with major histocompatibility complex (MHC) class II we introduced the gene encoding the 65 kDa heat-shock protein (ML65hsp) into a retroviral shuttle vector (pZIPNeoSV(X)) and transfected the murine macrophage cell line J774G8. S1 nuclease mapping and Western blot analysis of the transfected cell line (CJ11) showed that specific messenger RNA and ML65hsp antigen were stably expressed. Presence of antigen at the cell surface was demonstrated by flow cytometric analysis with specific monoclonal antibodies (mAb). Antigen-specific T lymphocytes were stimulated by CJ11 cells to proliferate and release interleukins (IL-2 and IL-3). These responses were blocked by mAbs specific for either MHC class II or for the mycobacterial antigen. The endogenous antigen was also recognised by MHC class I-dependent cytotoxic T cells; cytotoxicity was inhibited by mAbs against either MHC class I molecules or ML65hsp. Thus, production of ML65hsp within the host cytoplasm resulted in association of the antigen with both MHC class I and MHC class II antigen-presenting structures and evoked both lymphocyte proliferation and cytotoxicity towards the antigen-presenting cell. These findings may be relevant to the development of recombinant subunit vaccines against intracellular pathogens.

3T3 Cells↗
PubMed1992

Tumor necrosis factor and macrophage activation are important in clearance of Nocardia brasiliensis from the livers and spleens of mice.

The roles of tumor necrosis factor (TNF) and macrophage activation in clearance of Nocardia brasiliensis from BALB/c mouse livers and spleens were evaluated. TNF activity was detectable in sera from animals at all stages of infection. Treatment of infected mice with an antiserum against TNF significantly enhanced the experimental infection as judged by enumeration of CFU in the spleens and livers of infected mice. In another set of experiments, a population of activated macrophages from the peritoneal cavities of N. brasiliensis-infected mice was studied by using a cytostatic assay. The observed cytotoxic activity of these activated macrophages against L929 cells was mediated by TNF, since this activity was inhibited by anti-TNF antiserum treatment. The level of TNF activity generated in vitro in the presence of lipopolysaccharide (LPS) by peritoneal macrophages from infected mice was higher than that of adherent peritoneal cells obtained from normal mice after challenge with LPS. When the nocardiacidal activity of peritoneal cells from N. brasiliensis-infected mice was estimated in vitro, a significant decrease in the number of CFU recovered was observed. Moreover, nocardiacidal activity of peritoneal cells obtained from N. brasiliensis-infected mice previously treated with anti-TNF antiserum was significantly reduced compared with the activity of cells obtained from infected mice previously treated with normal rabbit serum and that of cells from uninfected mice. These data suggest a role for TNF in resistance to N. brasiliensis infection.

Animals↗
PubMed1992

Serum levels of tumor necrosis factor in insulin-dependent diabetic patients.

We determined the serum concentrations of tumor necrosis factor (TNF) in 15 nondiabetic healthy subjects and in 36 insulin-dependent (type I) diabetic outpatients. The mean (+/- SD) annual fasting plasma glucose, urine glucose and HbA1 levels of the diabetic group were 179 +/- 71 mg/dl, 13.0 +/- 13.2 g/day and 12.3 +/- 1.3%, respectively. The mean serum TNF concentration measured by immunoradiometric assay of the diabetic group (8.6 +/- 1.9 pg/ml) was significantly higher than healthy controls (6.9 +/- 0.9 pg/ml). Within the diabetic group, there was no correlation between serum TNF levels and either duration of diabetes or indices of metabolic control. However, serum TNF levels progressively increased from the well to the poorly controlled diabetic groups: 8.1 +/- 1.5 (G), 8.2 +/- 1.4 (F) and 9.4 +/- 2.4 (P) pg/ml, respectively, which parallel levels of HbA1 (%): 8.4 +/- 2.4, 11.7 +/- 1.8 and 14.6 +/- 1.2, respectively. Serum TNF levels of the diabetic patients with chronic complications (N = 7, 9.5 +/- 2.3 pg/ml) and without complications (N = 29, 8.4 +/- 1.7 pg/ml) were statistically higher than control subjects. The progressive increase of the serum TNF levels from the well to the poorly controlled diabetic groups suggests a relationship between levels of this cytokine and protein glycosylation.

Adolescent↗
PubMed1978

Enzymes of the carbohydrate metabolism in salivary glands from rats submitted to excess of vitamin A.

Male albino rats of the Wistar strain were submitted to daily doses of 15 000 I.U. of vitamin A. Enzymes of the carbohydrate metabolism were assayed in the salivary glands after 1,2, 3 and 4 doses. Phosphofructokinase showed decreased activity in the submandibular gland while it was not affected in the parotid. Glucose-6-phosphate dehydrogenase activity was higher in the submandibular glands of all experimental groups and only in the group of 1 dose for the parotid gland. Hexokinase activity did not alter in the submandibular gland while for parotid it showed higher activity only in the group of 1 dose. Pyruvate kinase activity was different only in the group of 3 doses for both glands.

Animals↗
PubMedDate not supplied

[Nursing audit].

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Nursing Audit↗