Biomedical subjects
Publications and source records attributed to A Restrepo.
A case of pulmonary paracoccidioidomycosis with spontaneous regression of the roentgenologic lesions, is reported. Regression of lesions took place within ten weeks, with the original infiltrates being replaced by fibrotic lines. The implication of this finding in the pathogenesis of paracoccidioidomycosis is analyzed.
The results of ketoconazole therapy in 38 patients with active paracoccidioidomycosis are described. Treatment consisted of a 200 mg tablet a day for 6 months. Evaluation was accomplished by means of a scoring system and the results were as follows: none of the patients worsened during therapy, one was found to be unchanged, five had minor improvement, 330 had major improvement, and there was complete resolution of the pretherapy conditions in 13. These findings plus the lack of toxicity of the drug and the facility for oral administration, make of ketoconazole a first line drug for the treatment of paracoccidioidomycosis.
Twenty-four paracoccidioidomycosis patients who completed a course of therapy with ketoconazole were followed for 12 months after treatment, and 10 of these patients were followed for 24 months. Only two of these patients relapsed; the remaining continued in remission. There were no fatalities. Immunologic tests showed decreased antibody activity and increased skin test reactivity to paracoccidioidin in comparison with the results obtained at the end of therapy. These findings indicate that ketoconazole therapy has improved the prognosis of patients with paracoccidioidomycosis.
Paracoccidioidomycosis, a disease caused by Paracoccidioides brasiliensis, which is endemic to Latin America, is much more common in men than women, suggesting a role for hormonal factors. We recently showed that two other yeasts possess steroid binding proteins and postulated that these receptor-like molecules represented a mechanism by which the hormonal milieu of the host might influence an infecting pathogen. Therefore, we examined P. brasiliensis for a sex steroid binding protein. Because tritiated steroids rapidly dissociated from the other fungal binding proteins, we developed a fast binding method with Sephadex G-50 microcolumns speeded by centrifugation. This method detected specific binding of [3H]estradiol in P. brasiliensis cytosol. Other tritiated steroid hormones, including testosterone and corticosterone, failed to exhibit specific binding. Scatchard analysis of [3H]estradiol binding showed an apparent dissociation constant (Kd) of 1.7 X 10(-8) M and a maximal binding capacity (Nmax) of 235 fmol/mg of protein. Susceptibility to trypsin indicated the binding site was protein in nature. The protein had a Stokes radius of approximately equal to 32 A by HPLC exclusion column and a sedimentation coefficient of 4.4 S by sucrose gradient, consistent with an apparent Mr of approximately equal to 60,000. Competition experiments revealed that estrone, estriol, and progesterone had 25% of the affinity of estradiol, whereas diethylstilbestrol, androgens, and corticosteroids had low affinity. Investigation of steroid hormone actions in P. brasiliensis indicated that estradiol inhibited the fungal transformation from mycelial form to yeast form, the initial step of infection. This suppressive effect was dose-dependent and not found with testosterone. We hypothesize that endogenous estrogens in the host, acting through the cytosol binding protein in the fungus, inhibit mycelial-to-yeast transformation, thus explaining the resistance of women to paracoccidioidomycosis.
The frequencies of blood groups, Rh and HLA antigens were studied in a series of patients with paracoccidioidomycosis as well as in control subjects. Statistical analysis of the results showed that only 2 antigens (HLA-A9 and HLA-B13) had a significantly increased frequency among patients with paracoccidioidomycosis compared with healthy controls. Among patients with paracoccidioidomycosis antigen HLA-A9 was significantly more prevalent in progressive pulmonary forms of the disease than in patients with extra pulmonary involvement. These observations suggest that HLA-A9 may influence susceptibility to the mycosis as well as its course.
The viability of Paracoccidioides brasiliensis yeast-form cells was determined by colony-forming units, direct fluorescent staining, and production of germ tubes in slide culture. The first procedure was unreliable and time consuming; the latter two showed better correlation with hemacytometer total cell counts and required significantly less time.
An experimental model for the study of paracoccidioidomycosis was established in BALB/c mice. Both normal and athymic nu/nu animals were challenged intraperitoneally and intratracheally with yeastlike cells of Paracoccidioides brasiliensis. After challenge, all immunologically intact (+/+) mice survived, whereas nu/nu mice gradually succumbed. The latter had focal peritoneal, liver, spleen, and lung lesions consisting of P. brasiliensis with inflammation, polymorphonuclear leukocytes, monocytes, and histiocytic reactions, but no granuloma formation. Thymus transplantation heightened resistance of nu/nu mice to P. brasiliensis. These studies indicate that the nu/nu mouse develops progressive lethal paracoccidioidomycosis after intraperitoneal and intratracheal challenge, and that thymus-dependent immune mechanisms mediate host defense.
Surgical specimens were obtained from a patient who had had life-threatening paracoccidioidomycosis 5 years previously. Residual lesions were found in the mesenteric lymph nodes; there were areas of caseous necrosis separated from the surrounding tissue by a fibrous capsule made of connective tissue. Abundant P. brasiliensis cells, many of which appeared degenerated, were observed in the necrotic material. Primary isolation was possible only under the microaerophilic conditions offered by fluid media kept stationary at 36 degrees C. Cultures in solid media were obtained after serial passages and gradual accommodation of the strain to aerobic incubation. It is apparent that P. brasiliensis yeast cells can become accustomed to reduced oxygen tension in the tissues. In this way, they are able to withstand the passing of time without completely losing their viability.
The ability of P. brasiliensis yeast cells to withstand microaerophilic conditions was investigated in a liquid medium distributed in tall columns in screw-capped tubes. Young cells of three isolates were inoculated on top of the medium, and the tubes were incubated aerobically and anaerobically at 36 degrees C for 28 days. The viability of cells that had sedimented to the bottoms of the tubes was studied by fluorescent microscopy and by their capacity to resume growth when transferred to fresh medium under continuous agitation. The proportion of viable cells in the sediments diminished with time of incubation. However, after 28 days, 27% of the cells were still viable and fully capable of active growth when placed under adequate aeration. On the other hand, drastic reduction of oxygen access elicited an accelerated death rate, with no survival after 7 days of incubation.
Ketoconazole, a new oral imidazole derivative, was employed for the treatment of five patients with paracoccidioidomycosis. The response was excellent, with objective clinical improvement and healing of both mucocutaneous and pulmonary lesions. Mycological and serological tests, as well as delayed hypersensitivity, were assessed and found to correlate with clinical improvement. Therapy was conducted for 12 months with a dose of 200 mg day in 2 patients; in the remainder the dose was reduced (100 mg day) after the first 6 months and maintained as such for an equal period. No side-effects or toxicity were noted despite prolonged treatment. The advantages of the new therapeutic approach are discussed.
A total of 60 clinical isolates of Paracoccidioides brasiliensis were tested for susceptibility to sulfadiazine and sulfadimethoxyne by the agar dilution technique. A modification of the Mueller-Hinton medium was devised which gave good growth of the yeast form. The minimum inhibitory concentrations for only 51.6% of the isolates were in the range of the recommended blood serum concentration (50 micrograms/ml). For 6 to 8% of the isolates, the minimum inhibitory concentrations were above 200 micrograms of both sulfadiazine and sulfadimethoxyne per ml. A significant decreases in susceptibility was demonstrated for one isolate obtained from a patient relapsing during sulfonamide therapy.
A slight modification of the chemically defined medium of McVeigh and Morton resulted in an excellent substratum for the cultivation of Paracoccidioides brasiliensis yeast phase.
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Miconazole, a parenterally administered imidazole antifungal agent has been shown to produce responses in systemic fungal infections in man. Ketoconazole, an analogue, can be given by mouth. It is inhibitory in vitro at low concentrations to most fungi. Blood levels after oral administration to animals and man greatly exceed these inhibitory concentrations for several hours. The efficacy of this drug has been demonstrated in animal models. Initial clinical evaluation has produced responses to therapy with 200-400 mg/day in 13 of 16 evaluable patients with systemic and superficial fungal infections, involving 10 fungal pathogens. No toxicity has been noted to date in these human studies. Ketoconazole is a promising agent needing further extensive evaluation.
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Explore the source record for details and available documents.
Serum electrophoresis patterns and various measures of specific and non-specific immune competence were determined in 16 patients with paracoccidioidomycosis, at time of diagnosis and 6 months after therapy. The results were compared with those furnished by the study of 16 control subjects, matched by age and sex. Once treated, the patients approached normality in some parameters. Untreated patients had significantly diminished albumin levels with increased alpha 1, alpha 2 and gamma fractions. Immune gamma globulin G (IgG) was elevated and remained so during therapy. Both before and after treatment patients had diminished total numbers and decreased percentages of E rosettes; they also had depressed lymphocyte transformation with phytohemagglutinin (PHA) and paracoccidioidin (P). Also, untreated patients exhibited the lowest skin test responses to PHA, purified protein derivative (PPD), P and candidin (C); significant differences, however, were limited to the former 2 antigens. All untreated patients had detectable antibody titers against P. brasiliensis; these titers had a tendency to drop during treatment. No direct correlation was found between elevated serum fractions, presence of antibodies and depressed cellular immunity.