Search PubMed⌕ Search

Biomedical subjects

A Restrepo

Publications and source records attributed to A Restrepo.

At least 55 records · Page 3Linked to original sources
PubMed1997

Cross-reactivity in Histoplasma capsulatum variety capsulatum antigen assays of urine samples from patients with endemic mycoses.

We evaluated cross-reactivity in the antigen assay used for the diagnosis of histoplasmosis by testing urine samples from patients with disseminated fungal infections. The mycoses chosen for this study were selected on the basis of the observation that during clinical testing, cross-reactions may occur between Histoplasma capsulatum var. capsulatum, Paracoccidioides brasiliensis, Blastomyces dermatitidis, Coccidioides immitis, and Penicillium marneffei. We detected antigen in 12 of 19 patients with blastomycosis, 8 of 9 with paracoccidioidomycois, in 17 of 18 with P. marneffei infection, and in one with disseminated H. capsulatum var. duboisii infection. Cross-reactions were not observed in the assays for six patients with disseminated coccidioidomycosis. Cross-reactivity between the agents of other endemic mycoses should be considered in interpreting a positive H. capsulatum var. capsulatum antigen assay. Antigen detection may provide a rapid, provisional diagnosis for patients with serious infections caused by one of these organisms.

Antigens, Fungal↗
PubMed1997

Development of a novel antigen detection test for histoplasmosis.

Histoplasmosis is an important systemic fungal infection, particularly among immunocompromised individuals living or travelling in areas of endemicity, who, without antifungal therapy, may develop a progressive disseminated fatal infection. For such patients, the detection of antibody responses by immunodiffusion or complement fixation test is of limited use. In contrast, the detection of Histoplasma capsulatum circulating antigens may provide a more practical approach to the rapid diagnosis of the disease. Accordingly, an inhibition enzyme-linked immunosorbent assay (ELISA) for the detection of a 69- to 70-kDa H. capsulatum-specific determinant and incorporating a species-specific murine monoclonal antibody was developed. With sera from patients with different forms of the disease (n = 35), the overall sensitivity of the test was found to be 71.4%, while the specificity was found to be 98% with normal human sera from areas of endemicity (n = 44) and 85.4% with sera from patients with other chronic fungal or bacterial infections (n = 48). This novel, highly specific ELISA provides a significant addition to the existing diagnostic tests for the detection of histoplasmosis.

Adolescent↗
PubMed1997

Use of monoclonal antibodies in diagnosis of paracoccidioidomycosis: new strategies for detection of circulating antigens.

The precise diagnosis of paracoccidioidomycosis, in most cases, is established by direct methods and indirect immunological tests. The latter method is reliant on the identification of the host's humoral responses, which are usually impaired or absent in patients with severe juvenile forms of the disease and in immunocompromised patients. Determining disease activity or assessing treatment responses by measuring antibody levels is difficult, since antibody titer may remain elevated or persist at stationary levels, even in the presence of clinical improvement. Consequently, there is a need for alternative tests aimed at the identification of circulating antigens. A modification of the standard hybridoma production method was used to raise a panel of murine monoclonal antibodies (MAbs) against the yeast form of Paracoccidioides brasiliensis. Of these, MAb PIB, directed against an 87-kDa determinant, was used to develop an inhibition ELISA (inh-ELISA) capable of detecting as little as 5.8 ng of circulating antigen per ml of serum. Sera from 46 patients with paracoccidioidomycosis or other mycoses and sera from healthy individuals were evaluated by the inh-ELISA; overall sensitivity was 80.4% (37 of 46 paracoccidioidomycosis patients tested positive), and specificity compared with that of normal controls from areas of endemicity was 81.4%. The inh-ELISA detected circulating antigen in 100% of patients with the acute form of paracoccidioidomycosis and in 83.3 and 60% of patients with the chronic multifocal and unifocal forms of paracoccidioidomycosis according to the patients' clinical presentation. These results indicate that the inh-ELISA with MAb PIB is effective in the detection of circulating antigen and that this test may be useful for monitoring responses to treatment and establishing disease prognoses.

Antibodies, Fungal↗
PubMed1997

[The value of immunological assays in the diagnosis of meningeal histoplasmosis].

INTRODUCTION: Between 1985 and 1995, 3,860 cerebrospinal fluid (CSF) samples from patients with mycotic meningitis were analyzed. METHODS: Direct examination, cultures, complement fixation (CF) and immunodiffusion (ID) with Histoplasma capsulatum were carried out. RESULTS: Seventy four samples from 31 patients (three of them with AIDS) were reactive at the immunological assays. Cultures were positive in five patients. In 26 patients the clinical diagnosis together with positive CSF assays gave indirect evidence of meningeal histoplasmosis. ID and CF reactivity were 93.5% and 100% respectively. For 23 patients who had simultaneous examination of blood and CSF the double positivity was 78.2%. CONCLUSIONS: Because of the direct isolation of Histoplasma capsulatum is a difficult one, the diagnosis of subacute or chronic meningeal histoplasmosis may be confirmed by indirect immunological assays.

Adolescent↗
PubMed1996

Molecular cloning, nucleotide sequencing, and characterization of a 27-kDa antigenic protein from Paracoccidioides brasiliensis.

A gene encoding a 27-kDa antigenic protein from Paracoccidioides brasiliensis was cloned, sequenced, and characterized. A cDNA library of the mycelial phase was produced and packed in Uni-Zap-XR vector, lambda Zap II synthesis kit (Stratagene, La Jolla, Ca). The screening of the library was carried out using a pool of sera from paracoccidioidomycosis patients that had proven reactive in serological testing. Among 44,000 immuno-screened clones from the library, 2 were positive (clones 2 and 3). The former was not characterized further. The latter has a 1-kb DNA insert with an open reading frame encoding a protein of 259 amino acids with a predicted molecular mass of 28.6 kDa (27 kDa by SDS-PAGE). This protein corresponds to a 25-kDa protein in antigenic preparations of P. brasiliensis as determined by Western blot analysis. Comparison of the transcribed sequence with different gene banks failed to reveal a high degree of homology with other proteins. The cloned DNA fragment was easily expressed in Escherichia coli without the need of induction by isopropyl-beta-D-thiogalactopyranoside. These findings suggest that the gene encodes a P. brasiliensis-specific protein.

Amino Acid Sequence↗
PubMed1996

Disseminated histoplasmosis in children: the role of itraconazole therapy.

OBJECTIVES: To describe the clinical characteristics and laboratory diagnosis of seven children with disseminated histoplasmosis and evaluate the effectiveness of itraconazole therapy in this severe form of the mycosis as well as to determine the long term results of such treatment. METHODS: The diagnosis of histoplasmosis was based on the direct observation of Histoplasma capsulatum var. capsulatum and/or on the isolation of the fungus from pathologic materials; the results of the serologic tests were taken into consideration. Chest roentgenograms also contributed to the diagnosis. PATIENTS: The patients were seven rural children, five girls and two boys, ages 1 to 14 years (mean, 4.6), with a confirmed diagnosis of disseminated histoplasmosis and who had no underlying disease other than malnourishment. RESULTS: The seven children experienced a subacute febrile syndrome for 4 months accompanied by anorexia, weight loss and signs of reticuloendothelial involvement such as lymph node hypertrophy, hepatomegaly and/or splenomegaly. The lung revealed roentgenographic alterations consisting mainly of nodular infiltrates. All patients received itraconazole orally in a mean dosage of 7.2 mg/kg/day, for variable periods (3 to 12 months), depending on the individual response and the toxic effects of the medication. One of the patients who was improving after 1 month of treatment was taken from the hospital by his guardian against medical advice and died shortly afterward. The remaining six patients responded to the treatment with marked clinical improvement and showed negative cultures and decreases in anti-H. capsulatum antibody titers after 3 months of treatment. Only one patient, the youngest and most severely affected child, exhibited hepatotoxicity, which subsided when itraconazole was discontinued. Extended follow-up studies revealed no relapses. CONCLUSION: The results of this study indicate that itraconazole is effective for treatment of disseminated childhood histoplasmosis. More studies should be performed to determine the most appropriate dosage and the optimal duration of itraconazole treatment in children.

Adolescent↗
PubMed1996

Immunological characterization of a recombinant 27-kilodalton antigenic protein from Paracoccidioides brasiliensis.

We report the expression in Escherichia coli of a 27-kDa antigenic protein from Paracoccidioides brasiliensis. When analyzed by immunoblotting, this recombinant antigenic protein was recognized by antibodies present in the sera of 40 of the 44 paracoccidioidomycosis patients studied. No cross-reactions were observed with sera from patients with other mycoses (histoplasmosis, aspergillosis, cryptococcosis, sporotrichosis, and chromoblastomycosis) or with tuberculosis.

Antigens, Fungal↗
PubMed1995

In search of the natural habitat of Paracoccidioides brasiliensis.

Paracoccidioides brasiliensis (Pb) is the dimorphic fungus responsible for paracoccidioidomycosis (PCM), one of the most important systemic mycosis in Latin America where the disease is geographically restricted. The natural habitat of the causative agent remains undetermined. We are planning to use PCR-based technology in order to amplify specific DNA fragments. The high sensitivity of this technique may allow us to detect the natural habitat of Pb. In this study, we prepared a cDNA library from which we cloned a protein of approximately 27 kDa MW. When this recombinant antigenic protein was tested by the immunoblot technique, it was able to recognize antibodies in the sera of 91% of the PCM patients studied. No cross reactions were observed with sera from patients with other systemic mycoses. Presently we are sequencing and characterizing this clone, in order to design specific primers for amplification of Pb DNA.

Animals↗
PubMed1994

Treatment of tropical mycoses.

Several subcutaneous and deep-seated mycoses are either observed more frequently in the tropical areas or are restricted to certain regions within the tropics. These mycoses include sporotichosis, chromoblastomycosis, entomophthoromycosis, eumycetoma, lobomycosis, and paracoccidioidomycosis. In sporotrichosis and paracoccidioidomycosis, therapy often results in either complete resolution or marked improvement. For decades sporotrichosis has been treated successfully with potassium iodide, but recently the triazole compounds, especially itraconazole, have proved effective and free of major side effects. The usual therapy for paracoccidioidomycosis is sulfonamides or amphotericin B; the former requires prolonged treatment, whereas the latter causes a significant degree of toxicity. Various azole derivatives (ketoconazole, fluconazole, saperconazole, and itraconazole) allow shorter treatment courses, can be given orally, and are more effective. Presently, itraconazole is the drug of choice. Chromoblastomycosis is a difficult condition to treat, especially if it is caused by Fonsecaea pedrosoi. Several therapeutic approaches have been used, including heat, surgery, cryotherapy, thiabendazole, amphotericin B combined with flucytosine, and azole derivatives, but their success has been modest. A 65% response rate has been obtained with itraconazole given for periods of 6 to 19 months; in limited trials, saperconazole appears to be more effective and requires shorter treatment courses. Only a few patients with eumycetoma respond to therapy; 70% of patients with Madurella mycetomatis respond to prolonged treatment with ketoconazole. Griseofulvin has been tried in nonresponders with partial success. Limited data in patients with Fusarium species eumycetoma indicate good responses to itraconazole. Eumycetoma caused by Pseudallescheria boydii or Acremonium species has been refractory to therapy. Therapy of entomophthoromycosis is also difficult because the diagnosis is usually established late and not all patients respond to therapy; this situation applies to infection caused by either Basidiobolus haptosporus or Conidiobolus coronatus. Although there is no consensus, African physicians prefer to use potassium iodide or trimethoprim-sulfamethoxazole. Isolated reports indicate that the azole derivatives, including the triazoles, may be effective. As for lobomycosis, all attempts at medical treatment have failed. Surgery is successful only when the lesion is small and can be fully resected; repeated cryotherapy appears to be more successful.

Antifungal Agents↗
PubMed1994

Inhibitory effect of deferoxamine or macrophage activation on transformation of Paracoccidioides brasiliensis conidia ingested by macrophages: reversal by holotransferrin.

Conidia of P. brasiliensis ingested by murine macrophages at 37 degrees C showed enhanced transformation to yeast cells and further intracellular growth compared with conidia in culture medium alone. Treatment of macrophages with the iron chelator deferoxamine inhibited the intracellular conidium-to-yeast transformation. Cytokine-activated macrophages could also exert this inhibitory effect. Holotransferrin reversed the inhibitory effect of either deferoxamine or activated macrophages on intracellular conidium-to-yeast transformation. These results indicate that iron restriction is one of the mechanisms by which activated macrophages control the intracellular transformation of ingested conidia and growth of yeast cells.

Animals↗
PubMed1993

Factors associated with Paracoccidiodes brasiliensis infection among permanent residents of three endemic areas in Colombia.

The natural habitat of Paracoccidioides brasiliensis, the aetiologic agent of paracoccidioidomycosis, has not been determined. Consequently, the events leading to the acquisition of infection remain controversial. To identify factors associated with infection in endemic areas we conducted a survey in three rural communities in Colombia where we had previously diagnosed paracoccidioidomycosis in children. Permanent residents were surveyed taking into consideration environmental and occupational variables. Skin tests were used to classify subjects as infected or non-infected. Variables found associated with infection were: (i) community A: previous residence around Porce river and agriculture in vegetable gardens; (ii) community C: frequent use of specific water sources; (iii) community V: housekeeping activities, and (iv) total group: age > 25 years and contact with bats. Residents in communities with higher prevalence of infection were older, had more complex residence history, and referred more contact with armadillos than residents of communities with lower infection.

Adolescent↗
PubMed1993

Disseminated adiaspiromycosis in a patient with AIDS.

A case of disseminated adiaspiromycosis in an AIDS patient is described. The most notable characteristic of the infection was the extensive osteomyelitis exhibited by the patient. Positive cultures for Chrysosporium parvum var. parvum were obtained from pus taken from a lesion of the wrist during surgery as well as from sputum samples and a bone marrow aspirate. Treatment with amphotericin B controlled the fungal infection.

AIDS-Related Opportunistic Infections↗
PubMed1993

Paracoccidioidomycosis: an update.

This review summarizes knowledge on various aspects of paracoccidioidomycosis. Mycelial propagules, chlamydospores, and arthroconidia exhibit thermal dimorphism; arthroconidia are infectious in animals and, by electron microscopy, appear well provided for survival. The mycelial-to-yeast-phase transformation requires a strict control of glucan synthesis probably mediated by membrane enzymes. Hormonal influences on the transformation of the fungus (mycelium or conidium to yeast phase) have been demonstrated. Estrogen-binding proteins have been detected in the fungal cytosol, and during the transformation novel proteins are produced as a result of estradiol incorporation. Clinical forms have been better defined on the basis of better experimental models. Emphasis has been placed on the lungs as the portal of entry and on the existence of silent pulmonary infections. A specific Paracoccidioides brasiliensis antigen, the 43-kDa glycoprotein (Gp43), has been identified, characterized, and cloned. This has led to improved reproducibility and specificity of serologic tests. The depression of cell-mediated immune responses has been associated with severe disease in humans and in the experimental host. T-cell subsets in patients' tissues were characterized by means of monoclonal antibodies, and a reduced CD4/CD8 ratio was demonstrated. This has been related to alterations in lymphokine and tumor necrosis factor production, production of antigen-antibody complexes, etc. Amphotericin B has provided effective therapy. Azole derivatives have also improved prognosis and facilitated therapy. Itraconazole is presently the drug of choice, yet incapacitating sequelae (mainly pulmonary fibrosis) still constitute major problems.

Adult↗
PubMed1992

A Pan-American 5-year study of fluconazole therapy for deep mycoses in the immunocompetent host. Pan-American Study Group.

Eighty-eight immunocompetent patients with deep mycoses from eight countries were evaluated with the same protocol for efficacy of fluconazole monotherapy. Entry doses were raised from 100 to 400 mg as safety was shown in initial cohorts, and dosages up to 2,400 mg daily and durations up to 44 months were studied. Results were very similar in different countries. Twenty-seven of 28 evaluable patients with paracoccidioidomycosis, 13 of 19 with sporotrichosis, 14 of 16 with coccidioidomycosis, and eight of eight with histoplasmosis demonstrated objective responses to therapy, as did one patient each with zygomycosis and alternariosis. For these patients, relapses have been unusual thus far. In contrast, one patient with chromoblastomycosis responded but relapsed, and six did not respond; one patient with mycetoma responded but relapsed, and two did not respond. The drug was well tolerated by patients, including six who received intravenous therapy. In vitro susceptibility tests suggested that clinical response was correlated with susceptibility but that resistance did not preclude clinical response. Fluconazole therapy appears efficacious for several deep mycoses; dosages of greater than 200 mg daily may be needed for some diseases. The further evaluation of fluconazole for these entities is warranted.

Adolescent↗
PubMed1992

Saperconazole in the treatment of systemic and subcutaneous mycoses.

In a 2-year period, 30 patients with culture-proven mycoses (chromoblastomycosis, sporotrichosis, and paracoccidioidomycosis) were treated with the new orally administered triazole, saperconazole (SPZ) (R66905). The daily dose varied from 100 to 200 mg. All patients responded to treatment; the mean time required to heal the lesions and convert the cultures to negative was 3.5 months for sporotrichosis, 4.6 for paracoccidioidomycosis, and 9.0 for chromoblastomycosis. Evaluation by a scoring system indicated that 36.6% of the patients achieved complete resolution of the pretherapy abnormalities, while the remaining (63.3%) experienced major improvement. No collateral effects were reported; there were no bone-marrow or liver toxicities. SPZ is an effective drug for the treatment of the above-mentioned mycoses and appears to be suitable for the control of chromoblastomycosis.

Administration, Oral↗
PubMed1992

Fate of conidia of Paracoccidioides brasiliensis after ingestion by resident macrophages or cytokine-treated macrophages.

Conidia ingested by resident macrophages had an enhanced percentage of transformation to yeast cells compared with those in culture medium without macrophages. The yeast cells subsequently grew intracellularly by budding. Macrophages treated with cytokines from antigen-stimulated spleen cells from immunized mice significantly inhibited transformation of ingested conidia.

Animals↗
PubMed1992

Development of pulmonary fibrosis in mice during infection with Paracoccidioides brasiliensis conidia.

Pulmonary fibrosis is a feared sequelae of paracoccidioidomycosis. We sought to determine if mice exposed to Paracoccidioides brasiliensis conidia would develop pulmonary fibrosis. BALB/c mice were infected intranasally with P. brasiliensis conidia and sacrificed at regular intervals. One lung was sectioned for histopathology and sections were stained with haematoxylin and eosin, trichromic and argentic stains; the other lung was homogenized and cultured to determine the viability of the fungus. One week post-challenge, only small peribronchial foci were apparent. After 4 weeks, reticular fibres appeared disorganized and disrupted. Six to 8 weeks later peribronchial infiltrates were larger and appeared surrounded by reticular fibres; thick collagen I fibres were noticed in the infiltrated areas at this time. On weeks 10-12, infiltrates were confluent and reticular fibres were concentrated around the inflammatory foci; collagenization was apparent. Observations up to 16 weeks revealed diffuse involvement of the lung parenchyma with extensive collagenization. Lung cultures were always positive. We suggest that inhalation of P. brasiliensis conidia induces adverse lung responses leading to changes in the proportion of collagen fibres I and III.

Animals↗