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A Restrepo

Publications and source records attributed to A Restrepo.

At least 37 records · Page 2Linked to original sources
PubMed2000

Nitric oxide participation in the fungicidal mechanism of gamma interferon-activated murine macrophages against Paracoccidioides brasiliensis conidia.

Paracoccidioidomycosis, a systemic mycosis restricted to Latin America and produced by the dimorphic fungus Paracoccidioides brasiliensis, is probably acquired by inhalation of conidia produced by the mycelial form. The macrophage (Mphi) represents the major cell defense against this pathogen; when activated with gamma interferon (IFN-gamma), murine Mphis kill the fungus by an oxygen-independent mechanism. Our goal was to determine the role of nitric oxide in the fungicidal effect of Mphis on P. brasiliensis conidia. The results revealed that IFN-gamma-activated murine Mphis inhibited the conidium-to-yeast transformation process in a dose-dependent manner; maximal inhibition was observed in Mphis activated with 50 U/ml and incubated for 96 h at 37 degrees C. When Mphis were activated with 150 to 200 U of cytokine per ml, the number of CFU was 70% lower than in nonactivated controls, indicating that there was a fungicidal effect. The inhibitory effect was reversed by the addition of anti-IFN-gamma monoclonal antibodies. Activation by IFN-gamma also enhanced Mphi nitric oxide production, as revealed by increasing NO(2) values (8 +/- 3 microM in nonactivated Mphis versus 43 +/- 13 microM in activated Mphis). The neutralization of IFN-gamma also reversed nitric oxide production at basal levels (8 +/- 5 microM). Additionally, we found that there was a significant inverse correlation (r = -0.8975) between NO(2)(-) concentration and transformation of P. brasiliensis conidia. Additionally, treatment with any of the three different nitric oxide inhibitors used (arginase, N(G)-monomethyl-L-arginine, and aminoguanidine), reverted the inhibition of the transformation process with 40 to 70% of intracellular yeast and significantly reduced nitric oxide production. These results show that IFN-gamma-activated murine Mphis kill P. brasiliensis conidia through the L-arginine-nitric oxide pathway.

Animals↗
PubMed2000

Pathogenesis II: fungal responses to host responses: interaction of host cells with fungi.

Most of our knowledge concerning the virulence determinants of pathogenic fungi comes from the infected host, mainly from animal models and more recently from in vitro studies with cell cultures. The fungi usually present intra- and/or extracellular host-parasite interfaces, with the parasitism phenomenon dependent on complementary surface molecules. Among living organisms, this has been characterized as a cohabitation event, where the fungus is able to recognize specific host tissues acting as an attractant, creating stable conditions for its survival. Several fungi pathogenic for humans and animals have evolved special strategies to deliver elements to their cellular targets that may be relevant to their pathogenicity. Most of these pathogens express surface factors that mediate binding to host cells either directly or indirectly, in the latter case binding to host adhesion components such as extracellular matrix (ECM) proteins, which act as 'interlinking' molecules. The entry of the pathogen into the host cell is initiated by fungal adherence to the cell surface, which generates an uptake signal that may induce its cytoplasmic internalization. Once this is accomplished, some fungi are able to alter the host cytoskeletal architecture, as manifested by a rearrangement of microtubule and microfilament proteins, and this can also induce epithelial host cells to become apoptotic. It is possible that fungal pathogens induce modulation of different host cell pathways in order to evade host defences and to foster their own proliferation. For a number of pathogens, the ability to bind ECM glycoproteins, the capability of internalization and the induction of apoptosis are considered important factors in virulence. Furthermore, specific recognition between fungal parasites and their host cell targets may be mediated by the interaction of carbohydrate-binding proteins, e.g., lectins on the surface of one type of cell, probably a parasite, that combine with complementary sugars on the surface of host-cell. These interactions supply precise models to study putative adhesins and receptor-containing molecules in the context of the fungus-host interface. The recognition of the host molecules by fungi such as Aspergillus fumigatus, Paracoccidioides brasiliensis and Histoplasma capsulatum, and their molecular mechanisms of adhesion and invasion, are reviewed in this paper.

Animals↗
PubMed2000

Clues to the presence of pathogenic fungi in certain environments.

The presence of various pathogenic fungi in rather unsuspected hosts and environments has always attracted the attention of the scientific community. Reports on the putative role of animals in fungal infections of humans bear important consequences on public health as well as on the understanding of fungal ecology. Fungi are ubiquitous in nature and their great capacity for adaptation allows them to survive and indeed, to thrive, in plants, trees and other natural substrata. Nonetheless, we are just beginning to learn the significance that these diverse fungal habitats have on the increasing number of immunosuppressed individuals. The accidental or permanent presence of fungi in animals, plants, soils and watercourses should not be taken too lightly because they constitute the source where potential pathogens will be contracted. If those fungal habitats that carry the largest risks of exposure could be defined, if seasonal variations in the production of infectious propagules could be determined, and if their mode of transmission were to be assessed, it would be possible to develop protective measures in order to avoid human infection. Additionally, unsuspected avenues for the exploration of fungal survival strategies would be opened, thus enhancing our capacity to react properly to their advancing limits. This paper explores several ecological connections between human pathogenic fungi and certain animals, trees, waterways and degraded organic materials. The occurrence of such connections in highly endemic areas will hopefully furnish more precise clues to fungal habitats and allow the design of control programs aimed at avoiding human infection.

Animals↗
PubMed1999

Pulmonary bone marrow embolism in sickle cell disease.

We report an unusual lethal complication of sickle cell anemia. The patient was admitted with a diagnosis of acute chest syndrome and died shortly after that of respiratory failure. Autopsy revealed numerous deposits of bone marrow hematopoietic tissue occluding the microvascular circulation of the lung. Many causes of acute chest syndrome in sickle cell anemia have been identified, including bone marrow infarction leading to embolism of bone marrow fat. However, the release of bone marrow hematopoietic tissue leading to pulmonary vascular occlusion is not generally recognized premortem by treating physicians.

Adult↗
PubMed1999

Detection of the 70-kilodalton histoplasma capsulatum antigen in serum of histoplasmosis patients: correlation between antigenemia and therapy during follow-up.

Histoplasmosis is an important systemic fungal infection, particularly among immunocompromised individuals, who may develop a progressive disseminated form which is often fatal if it is untreated. In such patients, the detection of antibody responses for both diagnosis and follow-up may be of limited use, whereas the detection of Histoplasma capsulatum var. capsulatum antigens may provide a more practical approach. We have recently described an inhibition enzyme-linked immunosorbent assay (ELISA) for the detection in patients' sera of a 69- to 70-kDa H. capsulatum var. capsulatum-specific antigen which appears to be useful in diagnosis. To investigate its potential for the follow-up of histoplasmosis patients during treatment, antigen titers in the sera of 16 patients presenting with different clinical forms of histoplasmosis were monitored at regular intervals for up to 80 weeks. Sera from four of five patients with the acute form of the disease showed rapid falls in antigenemia, becoming antigen negative by week 14 (range, weeks 10 to 16). Sera from four patients with disseminated histoplasmosis showed falls in antigen levels; three of them became antigen negative by week 32; the fourth patient became negative by week 48. In contrast, antigen titers in four of six AIDS patients with the disseminated form of the disease remained positive throughout follow-up. Sera from only one patient who presented with the chronic form of the disease were analyzed, and this individual's serum became antigen negative by week 9. The inhibition ELISA is shown to be of particular use in the monitoring of non-AIDS patients with the acute and disseminated forms of the disease and may complement existing means of follow-up.

AIDS-Related Opportunistic Infections↗
PubMed1999

Ocular-adnexal lymphoid tumors: a clinicopathologic and molecular genetic study of 77 patients.

PURPOSE: To determine whether molecular genetic analysis of ocular-adnexal lymphoid tumors, combined with histopathology and tumor location, is helpful in predicting which patients will develop systemic lymphoma. METHODS: A combined retrospective and prospective study of 77 patients with ocular-adnexal lymphoid tumors was performed. The tumors were subdivided into conjunctival, orbital, and eyelid lesions, and all were studied using both routine histopathology and molecular genetic analysis. RESULTS: Most lesions (70%) were small cell lymphomas of the mucosa-associated lymphoid tissue type, and the majority of tumors (90%) contained monoclonal or oligoclonal populations of lymphocytes discovered on molecular genetic analysis. Additionally, 72% of tumors exhibiting clonality had more than one gene rearrangement. Fifty-three percent of patients developed extraocular lymphoma sometime during the course of their disease. Patients with gene rearrangements on Southern blot hybridization had a 52% incidence of nonocular disease, compared with 63% of those without rearrangements. Patients with conjunctival tumors had a 37.5% incidence of nonocular disease, those with orbital tumors had a 54% incidence, and those with eyelid tumors had a 100% incidence of nonocular lymphoma. Only two patients died as result of systemic lymphoma. CONCLUSIONS: Most ocular-adnexal lymphoid tumors are lymphomas of the mucosa-associated lymphoid tissue type. The majority of tumors exhibit gene rearrangements on molecular genetic analysis, and this technique was not helpful in predicting which patients would develop nonocular lymphoma. Tumor location did have predictive value: Conjunctival lesions had the lowest incidence of nonocular lymphoma, and lid lesions had the highest incidence. Even with disseminated disease, most patients have a favorable prognosis with treatment.

Adult↗
PubMed1999

Electrophoretic karyotype of environmental isolates of Paracoccidioides brasiliensis.

Five of the 12 environmental isolates of the dimorphic fungus Paracoccidioides brasiliensis known to date, were analysed by contour-clamped homogeneous electric field gel electrophoresis (CHEF). The electrophoretic pattern was shown to consist of five bands, with molecular size ranging from 3.2 to 10 Mb, a model quite similar to the one found in the clinical isolates previously tested and used here as controls. However, one of the bands in the environmental isolates had a lesser weight (7.2 Mb), than the one corresponding to the clinical counterparts (8.8 Mb). This resulted in a smaller genome, approximately 29.7 Mb. The small differences that were found indicate the presence of chromosome polymorphism in this fungus.

Animals↗
PubMed1999

Post-liver transplantation lymphoproliferative disorders with and without infusions of donor bone marrow cells.

Donor bone marrow cells (DBMC) infusions have been used in an attempt to decrease the untoward effects of immunosuppressive treatment and to improve immunocompetence in the post-liver transplantation (PLT) period. Between March 1987 and July 1996, 558 orthotopic liver transplantations were performed at Jackson Memorial Hospital/University of Miami. Of these, 164 patients (29%) received 10 x 10(8) DBMC/Kg using various schedules. All patients received similar immunosuppressive therapy. After a minimum follow up of 1 year, five cases of Posttransplant Lymphoproliferative Disorder (PTLD) were diagnosed in patients without DMBC (1.3%, 5/394) when compared with none (0/164) in patients who received DBMC (p = 0.15, Fisher). Four patients had malignant lymphoma and one a diffuse atypical lymphoproliferative disorder. All lymphomas were non-Hodgkin's B-cell type, three diffuse large cell lymphoma, and one mixed cell lymphoma. All PTLD tested positive for EBV by in situ hybridization. Lymphomas occurred at 2, 4, 6 months and 4 years PLT. The outcome was poor with one patient diagnosed at autopsy while two patients died a few days after diagnosis. An 8-year-old girl is the only long-term survivor (> 5 years) after a partial response to combination chemotherapy and radiation therapy. The patient with diffuse atypical lymphoproliferative disorder died 3 months later. All patients with PTLD had histologic evidence of liver rejection. Although there is no statistical significant difference between the two groups, a larger cohort of patients will determine the significance of DBMC in preventing PTLD. We believe that the infusion of cytotoxic donor T cells found in the DBMC might suppress EBV-related lymphomagenesis.

Adolescent↗
PubMed1998

Use of the 27-kilodalton recombinant protein from Paracoccidioides brasiliensis in serodiagnosis of paracoccidioidomycosis.

Paracoccidioidomycosis (PCM) is one of the most important endemic mycoses in Latin America; it is usually diagnosed by observation and/or isolation of the etiologic agent, Paracoccidioides brasiliensis, as well as by a variety of immunological methods. Although the latter are effective, two circumstances, cross-reactions with other mycotic agents and antigen preparation that is marked by extreme variability among lots, hinder proper standardization of the procedures. To circumvent this lack of reproducibility, molecular biology tools were used to produce a recombinant 27-kDa-molecular-mass antigen from this fungus; a sizable quantity of this antigen was obtained through fermentation of Escherichia coli DH5alpha, which is capable of expressing the fungal protein. The latter was purified by the Prep-Cell System (Bio-Rad); the recovery rate of the pure protein was approximately 6%. A battery of 160 human serum samples, consisting of 64 specimens taken at the time of diagnosis from patients with PCM representing the various clinical forms plus 15 serum specimens each from patients with histoplasmosis and aspergillosis, 10 each from patients with cryptococcosis and tuberculosis, 6 from patients with coccidioidomycosis, and 40 from healthy subjects, were all tested by an indirect enzyme-linked immunosorbent assay with the purified 27-kDa recombinant protein. The latter was used at a concentration of 1.0 microgram/well; there were three serum dilutions (1:1,000, 1:2,000, and 1:4,000). The experiment was repeated at least twice. The average sensitivity for both experiments was 73.4%; in comparison with the healthy subjects, the specificity for PCM patients was 87.5% while for patients with other mycoses, it was 58.7%. Important cross-reactions with sera from patients with aspergillosis and histoplasmosis were detected. The positive predictive value of the test was 90.4%. These results indicate that it is possible to employ recombinant antigenic proteins for the immunologic diagnosis of PCM and, by so doing, achieve high coverage rates. Furthermore, antigen reproducibility can now be ensured, thus facilitating inter- and intralaboratory standardization.

Antibodies, Fungal↗
PubMed1998

Morphological transition of Paracoccidioides brasiliensis conidia to yeast cells: in vivo inhibition in females.

Clinical paracoccidioidomycosis is 13 times more common in men than in women. Estrogen inhibits the transition of mycelia or conidia (the saprophytic form of Paracoccidioides brasiliensis) to yeasts (the parasitic form) in vitro. Here, we show that, in male mice that were infected intranasally (mimicking natural infection) the transition of conidia in bronchoalveolar lavage fluids to intermediate forms and yeasts occurred over 24 to 96 h; CFU and yeasts (shown by histopathology) increased subsequently. In females, transition did not occur and infection cleared. These events in vivo are consistent with epidemiological and in vitro observations, suggesting that female hormones block transition and are responsible for resistance.

Animals↗
PubMed1998

Antigenemia in patients with paracoccidioidomycosis: detection of the 87-kilodalton determinant during and after antifungal therapy.

Serological diagnosis and follow-up of paracoccidioidomycosis (PCM) patients have relied mainly on the detection of antibody responses by using techniques such as complement fixation (CF) and immunodiffusion. We recently described a novel inhibition enzyme-linked immunosorbent assay (inh-ELISA) which proved to be useful in the diagnosis of PCM via the detection of an 87-kDa determinant in patient sera (B. L. Gomez, J. I. Figueroa, A. J. Hamilton, B. Ortiz, M. A. Robledo, R. J. Hay, and A. Restrepo, J. Clin. Microbiol. 35:3278-3283, 1997). This test has now been assessed as a means of following up PCM patients. A total of 24 PCM patients, classified according to their clinical presentation (6 with the acute form of the disease, of whom two had AIDS, 12 with the multifocal form of the disease, and 6 with the unifocal form of the disease), were studied. The four human immunodeficiency virus-negative patients with acute PCM showed a statistically significant decrease in circulating antigen levels after the start of antifungal therapy. Antigen levels in this group became negative by our criteria (</=2.3 microgram/ml) before week 20 and remained so in three of four of these patients. In contrast, the two AIDS patients who also presented with the acute form of PCM showed no statistically significant decrease in circulating antigen levels even after 68 weeks of therapy. Taken together as a group, the patients with the multifocal form showed a statistically significant decrease in antigenemia after 28 weeks of therapy. In addition, five of six patients with the unifocal form became antigen negative by week 40. Antigen level decrease mirrored clinical cure in the majority of patients in all clinical groups; in contrast, measurement of anti-PCM antibodies via the CF test showed wide fluctuations in titers during the follow-up period. The inh-ELISA for the detection of the 87-kDa Paracoccidioides brasiliensis determinant would appear to be a valuable additional tool in the follow-up of PCM patients.

AIDS-Related Opportunistic Infections↗
PubMed1998

Experimental pulmonary fibrosis induced by Paracoccidioides brasiliensis conidia: measurement of local host responses.

Pulmonary fibrosis was induced following inoculation of Paracoccidioides brasiliensis conidia intranasally in BALB/c mice. Fibrosis was associated with formation of granulomas, increase in lung hydroxyproline, and sustained increases in tissue tumor necrosis factor-alpha and transforming growth factor-beta. This study suggests a role for these cytokines in generation of pulmonary fibrosis associated with chronic granulomatous infectious diseases.

Animals↗
PubMed1998

Natural history and prognostic factors for survival in patients with acquired immune deficiency syndrome (AIDS)-related primary central nervous system lymphoma (PCNSL).

The incidence of primary central nervous system lymphoma (PCNSL) is increasing rapidly. It will be the most common primary malignant neoplasm of the brain by the year 2000. PCNSL is an important lethal complication in acquired immunodeficiency syndrome (AIDS) patients. Our objective was to study the natural history and prognostic factors for survival in patients with AIDS-related PCNSL. This is a retrospective cohort study of 75 patients with the diagnosis of AIDS-related PCNSL followed at Jackson Memorial Hospital/University of Miami. Medical records were abstracted for information about age, gender, race, and ethnicity. The method of diagnosis, treatment, and outcome of AIDS and PCNSL in this group were examined. Univariate and multivariate analyses were performed to identify prognostic factors for survival. The median age was 37 years. Males comprised 84% of the patients and 55% of the patients were Hispanic. The most common human immunodeficiency virus (HIV) risk factors were homosexuality and multiple sexual partners. The median cluster designation (CD) 4 count was 15/microl and the median lactic dehydrogensase (LDH) was 1.5x normal. Computed-assisted tomographic (CT) scans of the brain showed multiple lesions in 44% of the patients. Single-photon emission CT scan (SPECT) Thallium-201 of the brain was performed in two-thirds of patients. The most common histologies were immunoblastic and large cell lymphoma. Cranial radiation was given to 72% of the patients, and 55% of them did not complete treatment. The median survival of the group was 1.3 months. Univariate and multivariate analysis showed that longer survival was associated with good performance status (ECOG = 1 to 2 vs. 3 to 4). The presence of prior opportunistic infections, risk factors for AIDS, CD4 counts, level of LDH, ethnicity, gender, duration of symptoms before diagnosis, and race did not influence survival. PCNSL is a neoplasm with a very poor prognosis and short survival even with CNS radiation therapy. Performance status appears to be the main prognostic factor for survival. No significant differences in presentation or outcome were detected between the Hispanic and non-Hispanic patients.

Adult↗
PubMed1998

Is central nervous system prophylaxis necessary in ocular adnexal lymphoma?

PURPOSE: To examine the frequency of metastasis to the eye and central nervous system (CNS) from ocular adnexal lymphomas and to evaluate whether CNS prophylaxis is appropriate for these tumors. PATIENTS AND METHODS: Seventy-one patients with biopsy-confirmed ocular adnexal lymphomas were evaluated between 1989 and 1995. The lymphomas were subclassified histopathologically according to the new Revised European-American Lymphoma (REAL) criteria. Molecular genetic analysis of tumor cell DNA was done by Southern blot. Patients had a complete ophthalmologic evaluation and metastatic work-up and were then routinely followed up by an ophthalmologist and a medical oncologist. RESULTS: The 34 men and 37 women studied had a median age of 67 years (23 to 92). Ocular adnexal lymphomas were situated in the orbit in 54 patients, in the conjunctiva in 14 patients, and in the eyelid in 3 patients. Bilateral involvement occurred in 11 patients. The most common histologic diagnoses were (54 patients, 76%) extra-nodal marginal zone lymphomas and small lymphocytic lymphomas in 10 patients (14%). Molecular genetic analysis performed in all patients confirmed a monoclonal B-cell population in 55 patients (77%), including a single rearrangement of the immunoglobulin heavy chain gene in 14 patients, and more than two rearrangements in 41 patients. No patients had isolated T-cell gene rearrangements. Localized ocular adnexal lymphoma was diagnosed in 43 patients (61%), 17 patients (24%) were found to have concurrent extraocular lymphoma on metastatic work-up and 11 patients (15%) had a previous diagnosis of systemic lymphoma before the onset of their ocular tumor. The median duration of follow-up was 20 months. Overall, 32 patients (45%) had tumors, which remained localized to the orbit adnexa. Eleven patients (15%) relapsed, but none had eye or central nervous system involvement nor required CNS-directed therapy. Although eight patients died, only two died as a direct result of systemic lymphoma. No patient received CNS prophylaxis with either intrathecal chemotherapy and/or radiation therapy. CONCLUSION: Ocular adnexal lymphomas are rare non-Hodgkin's B-cell lymphomas. Metastatic involvement of the eye or central nervous system is rare and CNS prophylaxis with radiotherapy or chemotherapy is unnecessary.

Adult↗
PubMed1998

Auricular chromoblastomycosis caused by Rhinocladiella aquaspersa.

An unusual case of chromoblastomycosis localized in the ear and caused by R. aquaspersa is presented. The patient was a 60-year-old male urban resident, who had had the disease for 5 years. The lesion was darkly pigmented, infiltrative and crusty. Sclerotic cells were seen on direct examinations and the fungus was recovered in culture and identified on the basis of the characteristic sporulation. Itraconazole therapy at a dose of 200 mg day-1 for 7 months produced complete healing.

Antifungal Agents↗
PubMed1998

Teaching medical mycology in the year 2000.

Medical mycology is of increasing interest to the basic scientist, pathologist, microbiologist and clinician. This interest has been prompted by the rising number of immunosuppressed patients with opportunistic fungal infections, the expanding boundaries of the so-called endemic mycoses, the recognition of several major new endemic mycoses and a variety of other emerging fungal infections, and the development of potent, non-toxic antifungal drugs to treat these infections. The world of mycology is changing dramatically, especially in developing countries which have only limited resources to cope with the impact of the compromised host and the introduction of costly new antifungal drugs. Consequently, there is an urgent need to increase our effectiveness as teachers of medical mycology at all levels and in all regions of the world.

Education, Graduate↗
PubMed1997

Electrophoretic karyotype of clinical isolates of Paracoccidioides brasiliensis.

Chromosomal DNA molecules were obtained from eight clinical isolates of Paracoccidioides brasiliensis during the early staged of the yeast to mycelial transformation process and were separated by contour-clamped homogeneous electric field gel electrophoresis. In seven of the isolates, it was possible to separate five bands, albeit with two different migration patterns (A and B). In the remaining isolate only four bands were observed (pattern C). The isolated chromosomes showed molecular sizes ranging from 3.2 to 10 Mb according to Schizosaccharomyces pombe molecular size standards. The three different patterns observed had bands of 3.2, 3.8, 4.1, 5.2, 6.7, 7.2, 8.8, and 10 Mb. These data imply that at least 30 Mb of the genome are organized as chromosomal macromolecules. Due to the fact that P. brasiliensis spheroplasts are difficult to obtain, technical details are provided.

Chromosomes, Fungal↗