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Biomedical subjects

M Franco

Publications and source records attributed to M Franco.

At least 181 records · Page 10Linked to original sources
PubMed1989

Histological and ultrastructural study of the inflammation evoked by Paracoccidioides brasiliensis antigen in previously immunized mice.

Bentonite particles uncoated and coated with soluble antigen of Paracoccidioides brasiliensis (Pb) were intravenously injected into mice with and without previous immunization with Pb antigen. The inflammatory reaction around the bentonite emboli in small lung vessels was quantitated and morphologically studied by light and electron (EM) microscopy, 2 to 8 days after challenge. In control nonimmunized animals, coated and uncoated bentonite particles caused mild and nonspecific inflammation made up by macrophages. By EM, they formed loosely aggregated clusters with cytoplasm containing few organelles and borders without interdigitation. In immunized mice injected with coated bentonite particles, the inflammatory area was significantly greater than that in nonimmunized animals in all periods of study with maximum difference at day 2. The inflammatory process at days 2 and 4 was characterized as mature granulomata, composed of macrophages with great number of organelles in the cytoplasm, large euchromatic nuclei and prominent nucleoli. Altogether these findings indicated a lesion with high metabolic activity, compatible with a granulomatous hypersensitivity reaction. At days 6 and 8, there was a change from mature to epithelioid granulomata, well demonstrated by EM which showed macrophages with characteristically interdigitated cytoplasmic borders. The results strengthen the importance of cellular immunity in the genesis of epithelioid granuloma in paracoccidioidomycosis and reinforce the usefulness of the present model in studies of the inflammatory cellular sequency and events in this mycosis.

Animals↗
PubMed1989

Effect of adenosine A1 analogue on tubuloglomerular feedback mechanism.

To evaluate further the role of adenosine in the transmission of tubuloglomerular feedback signals, we studied the effects of an adenosine receptor antagonist and an adenosine A1-receptor agonist on feedback-mediated changes in stop-flow pressure (SFP). In orthograde perfusion experiments conducted in anesthetized rats, systemic administration of the adenosine receptor blocker 1,3-dipropyl-8-sulfophenylxanthine (PSPX) did not inhibit feedback responses. Control SFP feedback responses averaged 9.7 +/- 0.65 before and 8.6 +/- 0.55 mmHg during systemic infusion of the receptor blocker. In retrograde perfusion experiments, intratubular administration of the A1 agonist (360 nM) N6-cyclopentyladenosine (CPA), added to a hypotonic solution, markedly enhanced feedback responses. This effect was completely prevented by coinfusion of PSPX. Addition of 10 mM of the antagonist to the CPA-containing solution attenuated SFP feedback responses to less than 1 mmHg (delta = 0.44 +/- 0.50). Furthermore, PSPX also inhibited feedback responses obtained with an isotonic solution alone. Furosemide, which has been shown to block normal SFP responses obtained with isotonic solutions, failed to block CPA-induced decreases in SFP. These data demonstrate that intraluminal administration of an adenosine A1 analogue causes feedback-mediated decreases in SFP and therefore support a role for adenosine receptors in the signal transmission pathway.

Adenosine↗
PubMed1989

Hypersensitivity pneumonitis to Paracoccidioides brasiliensis antigens in mice.

Hypersensitivity pneumonitis was induced in mice immunized with Paracoccidioides brasiliensis and challenged, one week later, with soluble (SPbAg) or particulate (PPbAg) antigen (formalin-killed yeast cells), administered by the intratracheal route. Between 24 and 48 h post-challenge, animals developed an interstitial and intra-alveolar pneumonitis. Macrophages and lymphocytes arranged focally into loose or mature granulomata were observed by light and electron microscopy. The distribution and fate of antigens was studied by immunofluorescence. Three hours after challenge with SPbAg the lungs showed linear fluorescent deposits, whereas after challenge with PPbAg the pattern was globular, corresponding to the particulate antigen. After 24 and 48 h, the pattern was diffuse and finely granular in both groups, with a decreasing number of animals showing detectable fluorescence. Immunization induced a positive footpad swelling test (FPT) in all animals. After pulmonary challenge, there was a significant decrease in FPT indices, interpreted as desensitization due to trapping of specifically sensitized lymphocytes in the lungs. In conclusion, immunization induced a marked cellular immune response, the inflammatory pattern and the tempo of the induced pneumonitis being compatible with delayed hypersensitivity in the lungs. Immunized mice also cleared the injected antigens rapidly. These data suggest that hypersensitivity pneumonitis may be an expression of pulmonary resistance to infection with P. brasiliensis.

Alveolitis, Extrinsic Allergic↗
PubMed1989

In situ localization of T lymphocyte subsets in human paracoccidioidomycosis.

Immunohistochemical techniques using monoclonal antibodies to T lymphocyte subsets were used to characterize granulomas caused by Paracoccidioides brasiliensis. Punch biopsies of skin or mucosa from eight patients and of lymph nodes from two patients with disseminated paracoccidioidomycosis were studied. The T lymphocytes were distributed either in a localized pattern related to epithelioid granulomas or in a diffuse arrangement, predominantly around the vessels. In the granulomas, T cells formed a peripheral mantle surrounding central aggregates of macrophages. The majority of lymphocytes were T-helper cells with few suppressor cells. In contrast, patients presented with a decreased number of peripheral T-helper lymphocytes and a corresponding decrease in helper-suppressor cell ratios. There was no clear-cut relationship between tissue helper-suppressor cell ratios and the level of cellular immunodepression of the patients. The lowest P. brasiliensis antibody titers were detected in patients with the highest tissue helper-suppressor cell ratios. The distribution pattern of T lymphocytes in P. brasiliensis granulomas, with a predominance of helper phenotype, suggests that these cells are actively involved in the disease process.

Adolescent↗
PubMed1989

[Nephrotic syndrome associated with ampulloma].

A patient is reported who presented simultaneously classic nephrotic syndrome and adenocarcinoma of the Vater ampulla. Morphological study of the renal biopsy revealed changes characteristic of membranous glomerulonephritis and subepithelial deposits. These deposits stained specifically for IgG and C'3 with a granular pattern, but deposits of CEA-antiCEA immune complexes were not found in glomerular capillaries. The association of nephrotic syndrome with lymphoproliferative diseases and a large variety of solid tumors, like carcinoma of the breast, bronchogenic, colon and stomach has been communicated, but the present case constitutes the first known association with adenocarcinoma of the Vater ampulla.

Adenocarcinoma↗
PubMed1988

Isolation and morphology of an immunoreactive outer wall fraction produced by spherules of Coccidioides immitis.

A previously undescribed, immunoreactive, membranous spherule outer wall (SOW) fraction produced by Coccidioides immitis (strains 634 and 735) grown in culture was isolated. Both this fraction and intact spherules were reactive with sera from coccidioidomycosis patients, as demonstrated by immunofluorescence microscopy. The serological activity of SOW was also demonstrated by its reactivity with human anti-C. immitis tube precipitin in a standardized immunodiffusion assay. Extraction of SOW with the nonionic detergent N-octyl-beta-D-glucopyranoside (OG) permitted the isolation of an OG-soluble fraction which was reactive in the immunodiffusion assay. Rabbit antisera raised against the OG-soluble fraction were used in immunofluorescence and immunoelectron-microscopic studies of the parasitic cycle to confirm that the immunoreactive components of the solubilized fraction of SOW were associated with the inner and outer layers of the spherule wall as well as with distinct cytoplasmic organelles observed in thin sections of spherules. The immunoreactivity of SOW with sera from patients suggested that infected individuals are exposed to this surface wall material isolated from in vitro-grown spherules.

Antigens, Fungal↗
PubMed1988

Immunoreactivity of a surface wall fraction produced by spherules of Coccidioides immitis.

The membranous spherule outer wall (SOW) isolated from liquid cultures of Coccidioides immitis has been shown to elicit reactivity with human anti-Coccidioides antibody by immunofluorescence and the immunodiffusion-tube precipitin assay. The serologically reactive components were extracted from SOW with the nonionic detergent N-octyl-beta-D-glucopyranoside (OG). The OG-soluble fraction of SOW was shown to be reactive with immunoglobulin G in 25 serum samples from coccidioidomycosis patients by an enzyme-linked immunosorbent assay. The isolated SOW and OG-soluble fraction of SOW were also demonstrated to be capable of eliciting lymphocyte blastogenesis. The antigenic and protein compositions of the OG-soluble fraction were examined by two-dimensional immunoelectrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. Two antigens which were extracted from SOW were identified as antigens 2 and CS on the basis of the coccidioidin-anticoccidioidin reference system. The latter was isolated earlier and shown to correspond to a molecular mass (Mr) of 19 X 10(3) by SDS-PAGE under reducing conditions. This same electrophoresis band was shown to be reactive with sera from coccidioidomycosis patients by immunoblot analysis. One other SDS-PAGE component of the OG-soluble fraction of SOW with an Mr of 66 X 10(3) was shown to be reactive with sera from patients by immunoblot analysis. The SOW of C. immitis represents an important reservoir of immunoreactive wall components which has not previously been reported.

Animals↗
PubMed1988

Evaluation of prostaglandins as mediators of tubuloglomerular feedback.

Orthograde and retrograde microperfusion experiments were conducted in Sprague-Dawley rats to evaluate the participation of vasoconstrictive eicosanoids as mediators of tubuloglomerular feedback (TGF) signals. Retrograde perfusion with 160 microM arachidonic acid (AA) added to a hypotonic solution enhanced the stop-flow pressure (SFP) feedback responses compared with those obtained with the control hypotonic solution (delta SFP, 1.6 +/- 0.4 vs. 10.1 +/- 0.7 mmHg with AA). Blockade of thromboxane A2 (TxA2) with the receptor blocker EP 092 or the synthesis inhibitor UK 38485 did not alter the magnitude of the SFP feedback responses obtained with an isotonic solution. Similarly, nordihydroguaiaretic acid, a lipoxygenase inhibitor, did not alter maximal SFP feedback responses. Although indomethacin (5 mM) did induce attenuated SFP feedback responses (delta SFP, 9.5 +/- 0.7 vs. 0.5 +/- 0.4 mmHg with indomethacin), normal feedback responses were restored within 15-90 s after cessation of indomethacin perfusion. Additionally, SFP feedback responses were not inhibited with 5 mM piroxicam, a different cyclooxygenase inhibitor. These data fail to support a role for either TxA2 or lipoxygenase end products as mediators of TGF signals. The rapid restoration of feedback responses after indomethacin exposure and the lack of blockade with piroxicam suggest that transmission of feedback signals is not dependent on cyclooxygenase products.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1987

Ketoconazole in the treatment of experimental murine paracoccidioidomycosis.

In a murine model of chronic disseminated paracoccidioidomycosis (strain 18; intravenous route), Ketoconazole (200 mg/kg in 0.2% agar) was given daily by gavage in three different schedules. Continuous treatment from an early stage of infection (day 3) up to week 20 was the most effective protocol, leading to remission of histopathological lesions and of both humoral and cellular anti-P. brasiliensis immune response, and clearance of the fungus in lungs; only 1 treated animal at week 20 showed pulmonary granulomas, although less extensive than control mice. Continuous treatment from early stage up to week 8, followed by a 16 week-period of drug discontinuity, caused remission of lesions in all but 3 treated mice which showed active pulmonary paracoccidioidomycosis similar to controls (14.2% of unresponsiveness to treatment). The continuous Ketoconazole protocol since a late stage of infection (week 4) up to week 20 produced a slower remission of lesions and immune response when compared with the first drug schedule. In this model of paracoccidioidomycosis, Ketoconazole showed no detectable side-effects and was a very effective drug especially in a prolonged administration protocol from an early stage of infection.

Animals↗
PubMed1987

Host-parasite relationships in paracoccidioidomycosis.

A viewpoint of host-parasite relationships in paracoccidioidomycosis is presented. The characteristics of the fungus which are important to the host-parasite interaction are discussed. Aspects of inhibition of mycelium-to-yeast transformation by estrogens acting at receptors on the fungal wall and in the cytoplasm, and the role of polysaccharide components of the cell wall in virulence are reviewed. The natural mechanisms of host defense are also examined, including phagocytosis, complement system, natural-killer cells and genetic control of resistance and susceptibility. Finally, a discussion of granuloma morphogenesis and its relationship to the humoral and cellular anti-P. brasiliensis immune response is presented.

Antibodies, Fungal↗
PubMed1987

Experimental pulmonary paracoccidioidomycosis in the Syrian hamster: morphology and correlation of lesions with the immune response.

A model for pulmonary paracoccidioidomycosis in the hamster is described. The disease was induced by intratracheal inoculation of 1.7 x 10(5) viable yeast forms of P. brasiliensis. Lung histopathology, dissemination lesions and humoral and cellular immune responses were investigated at intervals up to 24 weeks after infection. Humoral immunity was studied by immunodiffusion and complement fixation tests. Cell-mediated immunity was evaluated in vitro by the macrophage migration inhibition test in the presence of phytohaemagglutinin and P. brasiliensis soluble antigen, and in vivo by the paracoccidioidin test. Thirty out of 35 infected animals (85.7%) developed pulmonary paracoccidioidomycosis. Dissemination lesions were observed in regional lymph nodes (82.8%), liver (8.5%) and spleen (5.7%). Lung involvement was mainly around bronchi and vessels. Regional lymph nodes were severely involved from the fourth week on, acquiring a pseudotumoral aspect at later stages. Specific antibodies were detected from the fourth week on, with titres increasing progressively. The cellular immune response to phytohaemagglutinin was intact throughout the experiment and the response to P. brasiliensis antigen was already detectable by the second week and remained positive to the end of the experiment. The skin test became positive from the fourth week on. Inoculation by the intratracheal route represents a highly effective way of infecting hamsters with P. brasiliensis, with the induction of localized disease, good antibody production and intact cell immunity.

Animals↗