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D A Stevens

Publications and source records attributed to D A Stevens.

486 records · Page 27Linked to original sources
PubMedDate not supplied

Isolation of a human serum protein that inhibits the growth of Cryptococcus neoformans.

Human serum at 5 to 10% (v/v) in tissue culture medium RPMI-1640, inhibits the growth of Cryptococcus neoformans by 80 to 93%. Serum fractionated on molecular sieve columns (Sephadex G-200) yielded an active protein fraction. This fraction at 100 micrograms protein/ml inhibited the growth of C. neoformans by 54%. When an active G-200 fraction was applied to a dye affinity column (Affi-Gel Blue) the fraction with inhibitory activity was bound by the column and was eluted with 1.4 M NaCl in 0.1 M phosphate buffer (pH 7.4). The bound fraction at 62.5 micrograms protein/ml inhibited C. neoformans growth by 82%. On native polyacrylamide gel electrophoresis (Nu-PAGE) the bound fraction migrated as a major and a minor band. Under the reducing conditions of sodium dodecyl sulfate (SDS)-PAGE the bound fraction yielded 4 prominent bands with MW ranging from 175 kDa to 45 kDa. Purification of the active Sephadex G-200 peak was achieved using an anion exchange column (DEAE-Sephacel). Protein eluted with 0.1 M NaCl had strong anticryptococcal activity (12.5 micrograms/ml, 79% inhibition), which in SDS-PAGE migrated as a single band with an approximate MW of 85 kDA. This protein appears important in natural host resistance to C. neoformans and polymorphisms or deficiencies may have epidemiologic and diagnostic relevance.

Antifungal Agents↗
PubMedDate not supplied

Efficacy of oral saperconazole in systemic murine aspergillosis.

Saperconazole is a fluorinated bis-triazole. Groups of ten 5-week-old female CD-1 mice were infected intravenously with 5.5 x 10(7) Aspergillus conidia. Saperconazole, dissolved in hydroxypropyl-beta-cyclodextrin (HPBC), was given orally twice a day for 11 days, beginning 1 day post-infection, at 50, 100 or 200 mg kg-1 day-1. At day 18 post-infection, survivors were killed and residual infection quantified in the kidneys. With Aspergillus fumigatus isolate 10AF, 70% given no therapy, 100% given daily oral HPBC and 40% given intraperitoneal amphotericin B at 3.3 mg kg-1 three times a week for 2 weeks died, whereas all mice given saperconazole survived. Each saperconazole regimen prolonged survival compared to untreated or HPBC treated mice (P < 0.01). Saperconazole at 200 mg kg-1 day-1 reduced colony forming units of aspergillus in kidneys more than 1000-fold compared to untreated or HPBC treated mice (P < 0.001) and saperconazole regimens were superior to amphotericin B therapy (P < 0.01). In another study of the same design with A. fumigatus isolate 15AF, 90% of untreated and 20% of mice treated with saperconazole at 50 mg kg-1 day-1 died; all others survived. Any saperconazole regimen prolonged survival (P < 0.001). Residual infection was also significantly reduced by all saperconazole regimens (P < 0.01). With Aspergillus terreus isolate 4AT, 80% of untreated mice, 50% of mice treated with saperconazole at 50 mg kg-1 day-1 and 10% of mice treated at 200 mg kg-1 day-1 died. Any saperconazole regimen prolonged survival (P < 0.05). Saperconazole at 100 and 200 mg kg-1 day-1 also reduced residual infection (P < 0.001). No adverse effects were noted in any study. Thus, saperconazole was efficacious in vivo against different Aspergillus isolates.

Administration, Oral↗
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Therapy of systemic histoplasmosis in immunosuppressed mice with the triazole D0870.

Because histoplasmosis is a life-threatening disease in AIDS and other compromised patients, we examined the efficacy of D0870 (Zeneca) in immunosuppressed mice against systemic histoplasmosis. Oral therapy with fluconazole given once daily (QD) was ineffective in prolonging survival, whereas itraconazole given once or twice daily (BID), fluconazole given BID or D0870 given QD or given every other day (QOD) were efficacious (P < 0.001). Burdens of Histoplasma capsulatum in the liver and spleen of survivors showed that D0870 given QD or QOD and itraconazole given BID caused dose-responsive reduction of infectious burden. Infection was cleared more readily from the liver than from the spleen. Overall, D0870 was > or = 20-fold more efficacious than fluconazole or itraconazole and itraconazole was > ten-fold better than fluconazole for the treatment of systemic histoplasmosis in the immunosuppressed model.

Animals↗
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Colony phenotype switching in clinical and non-clinical isolates of Saccharomyces cerevisiae.

During studies on the virulence and genetics of isolates of Saccharomyces cerevisiae we noted colony phenotype switching. Virulent clinical (YJM128, YJM436) and avirulent non-clinical (Y55, YJM237) isolates of S. cerevisiae were scored for colony phenotypes and reversion rates of the switched second-generation colonies on YEPD with phloxine B. YJM128 produced six colony phenotypes; 99.7% were large (8-9 mm diameter), smooth, pink with a white edge (type A) and the other five types arose at frequencies ranging from 2 x 10(-3) to 5 x 10(-5). On replacing of type A, 98.8% of colonies scored arose as type A, 1.1% type J and 0.1% larger, but similar to type A indicating both stability and reversibility. YJM436 also varied, with 91.3% arising as a single phenotype; five other phenotypes were observed at frequencies ranging from 7.6 x 10(-2) to 1.5 x 10(-4). For Y55, 0.2% of the colonies were 5-7 mm in size with a ridged pink edge (type D); 36.4% of YJM237 were a 5-7 mm, smooth pink colony (type H). The remaining 99.8% of Y55 and 63.4% of YJM237 colonies arose as sectored or non-sectored non-reverting petites. These results indicate that virulent isolates of S. cerevisiae tend to produce multiple colony phenotypes, which are reversible. In contrast, avirulent isolates of S. cerevisiae showed single colony phenotypes and a high frequency of non-reverting petites. Whether selected colony phenotypes and switching are associated with the virulence of S. cerevisiae remains to be determined.

Humans↗
PubMedDate not supplied

Experimental systemic cryptococcosis in SCID mice.

The susceptibility of severe combined immune deficiency (SCID) mice to experimental systemic cryptococcosis was studied. SCID mice were at least 16-fold more susceptible to lethal infection than were immunocompetent control mice (P < 0.001). Histological assessment showed that control mice responded with a granulomatous inflammatory response, whereas SCID mice showed no evidence of a cellular host response. In a therapeutic study, 5 mg kg-1 day-1 of fluconazole caused a significant reduction in the infectious burden in the spleen, liver, kidney and lungs of treated mice compared with no treatment. These results indicate that a model of systemic cryptococcosis with meningitis in SCID mice may have utility in the study of immunology and therapy of this disease in the severely immunocompromised host.

Animals↗
PubMedDate not supplied

Application of DNA typing methods to Candida albicans epidemiology and correlations with phenotype.

The application of methods of Candida albicans DNA fragment length polymorphism analysis to correlations with phenotype and to questions in the epidemiology of Candida is shown. Twenty-nine different DNA types, in two broad classes, have thus far been demonstrated in 91 isolates. One type, IA2, was easily the most common (41% of isolates). A type is constant after multiple generations in vivo, as demonstrated in a mouse model. Isolates from individual medical centers were polymorphic, and DNA types were widely distributed geographically. Persons colonized with and/or having disease due to C. albicans at two or more body sites almost always had the same individual type. Sex partners studied had the same type in genital isolates. There was neither tight concordance nor random association of DNA type with previously described phenotypic groups. Likewise, some phenotypic characteristics were significantly associated with DNA type. Urogenital isolates were significantly associated with DNA type IA2. Colonizing and invading isolates included many different and overlapping DNA types. A cluster of cases in a hospital, previously reported to have been caused by a single organism (based on phenotypic studies), was shown to be due to multiple types. Phenotype switching, associated with transition from colonization to invasion, is suggested in these studies. The present series of studies demonstrates the application of DNA typing methods to classification and clinical problems.

Animals↗
PubMedDate not supplied

Antifungal and surgical treatment of invasive aspergillosis: review of 2,121 published cases.

No controlled trials of therapy for invasive aspergillosis have been done. This review appraises 2,121 cases reported in 497 articles in the literature and analyzes 440 courses of treatment of infection at various body sites in 379 patients. The exclusion of early failures of therapy skews the results toward a favorable outcome. The rate of response to amphotericin B is 55%. Mortality from pulmonary aspergillosis in bone marrow transplant recipients exceeds 94% regardless of therapy, as does that from cerebral aspergillosis in all hosts. Amphotericin B (1 mg/[kg.d]) with flucytosine lowers mortality in neutropenic patients with pulmonary aspergillosis who did not receive a bone marrow transplant; relapse is common. Surgical debridement of aspergillus maxillary sinusitis is usually curative in nonimmunocompromised patients, whereas it increases mortality among neutropenic patients. Valve replacement is essential for aspergillus endocarditis. Both vitrectomy and intravitreal amphotericin B treatment are essential for aspergillus endophthalmitis. Flucytosine is somewhat useful clinically. Itraconazole shows efficacy in the treatment of pulmonary, skeletal, and pericardial aspergillosis. Although liposomal amphotericin B is less toxic than standard preparations of the drug, relevant data are limited. The proposed potentiation of amphotericin B by rifampin is unsupported by clinical data. Despite "conventional" therapy, mortality from invasive aspergillosis remains high; new approaches must be investigated.

Amphotericin B↗
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Comparison of fluconazole and ketoconazole in experimental murine blastomycosis.

Fluconazole, a new oral triazole antifungal agent, was tested against Blastomyces dermatitidis in vitro and in a murine model (pulmonary challenge) and compared with ketoconazole, an oral imidazole known to be effective against this agent in mice and in humans. Although fluconazole appeared less active than ketoconazole in vitro, in experiments involving 3 weeks of treatment and 2 months of observation, fluconazole was greater than 10 times as potent (mg/kg) in vivo against blastomycosis (prolongation of life). In the model neither drug was curative at the doses and regimens used. A possible explanation for the efficacy of fluconazole in vivo is its favorable pharmacokinetic profile (i.e., prolonged serum concentrations that exceeded the MIC for the pathogen after oral administration). Dosages of 100 mg/(kg.d) were tolerated for 3 weeks without evident toxicity.

Animals↗
PubMedDate not supplied

Treatment of systemic sporotrichosis with ketoconazole.

Infections of deep soft tissues with the dimorphic fungus Sporothrix schenckii are uncommon in humans, and therapy has often required toxic drugs. We report our experience in treating 11 patients who had deep-seated sporotrichosis with ketoconazole, a well-tolerated, orally absorbed antifungal agent. Eight infections involved one or more joints, and three involved thoracic, cervical, and widespread cutaneous sites, respectively. For eight patients all evidence of infection resolved during therapy. Sustained remissions (6 months to 5 years) were noted for six patients after the discontinuation of all therapy and for an additional patient 4 years after the initiation of ketoconazole treatment. Durable responses were associated with prolonged treatment with 400-800 mg of ketoconazole daily. Our favorable experience suggests that oral therapy with ketoconazole may benefit other patients with systemic sporotrichosis.

Adult↗
PubMedDate not supplied

Endocarditis due to Trichosporon beigelii: in vitro susceptibility of isolates and review.

Infection with Trichosporon beigelii is an uncommon cause of endocarditis. Of the eight cases of T. beigelii endocarditis that have been reported (one herein and seven previously), six involved prosthetic heart valves and two involved native heart valves. The clinical manifestations of this infection included embolization of the superficial femoral artery or of the bifurcation of the posterior tibial and peroneal arteries in three of these patients (two with prosthetic valve and one with native valve endocarditis). In seven of the eight reported cases, blood cultures were positive for the organism. Although clinical isolates of the organism are generally reported to be susceptible to amphotericin B, isolates can vary in their sensitivities to antifungal agents in vitro depending on the methodology used, and clinical response to therapy with antifungal agents in a regimen that includes amphotericin B is generally poor. Only two of six patients who were treated with antifungal agents survived endocarditis caused by T. beigelii and were apparently cured; one of these patients was also managed surgically with valve replacement. Infection with T. beigelii should be considered in the differential diagnosis of endocarditis in immunocompetent patients, particularly those who have a prosthetic heart valve. Rapid, aggressive therapy may be necessary to eradicate this organism.

Adult↗
PubMedDate not supplied

Endophthalmitis in a patient with disseminated cryptococcosis and AIDS who was treated with itraconazole.

We report a case of presumed cryptococcal endophthalmitis that occurred in a patient with severe disseminated cryptococcosis and AIDS. Multiple small, spherical lesions appeared bilaterally on the surface of the retina 2 weeks after cryptococcal meningitis was diagnosed; the lesions were associated with multiple blind spots, blurred vision, and the perception of flaring of light. Over the next week, many more lesions with adjacent hemorrhages appeared. Therapy with itraconazole over the next 3 months resulted in complete resolution of the lesions. Cryptococcal endophthalmitis is a rare disease. Fewer than 20 cases, including five in patients with AIDS, have previously been reported. None of these patients regained normal vision.

Acquired Immunodeficiency Syndrome↗
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Criteria for evaluation of therapeutic response to antifungal drugs.

A therapeutic trial of antifungal therapy in humans requires not only well-defined objectives and a sufficient number of patients, but also standardized criteria for the diagnosis and evaluation of response, including the efficacy, failure, and toxicity of any new agent or treatment modality. Generally, the retention of a patient in a study should require, as a minimum, confirmation of the etiologic diagnosis by culture of the organism from the infected site. Two different systems for evaluation of therapy are proposed. The first is a set of definitions of response to therapy; these are adaptable for use in any type of prospective clinical trial and emphasize cure as the best possible outcome. The second system of evaluation employs scored criteria and thereby enables quantitative comparison of the status of a patient before therapy with his or her status at intervals during therapy, at the end of therapy, and at intervals after therapy. This system provides an objective means of measuring improvement in a given patient; thus it is most useful in those diseases in which significant improvement rather than cure is a more realistic goal of therapy, e.g., coccidioidomycosis.

Adult↗
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Ketoconazole: a new drug for the treatment of paracoccidioidomycosis.

Ketoconazole was administered orally to 13 patients with paracoccidioidomycosis. Therapy consisted of 200 mg per day for periods ranging from three to 12 months. All patients improved markedly, with healing of pulmonary, mucosal, and skin lesions. Patients exhibiting the latter two manifestations began to improve two weeks after therapy, and healing occurred within three months. Pulmonary lesions regressed at a slower pace and healed by fibrosis. Mycologic tests have corroborated the clinical improvement. Adverse effects were not observed; monitoring of renal, hematologic, and hepatic functions did not reveal any abnormalities. Five patients completed a year of therapy and were free of symptoms when therapy was discontinued. Of these patients, four were followed for several months and had no relapses; the fifth patient developed tuberculosis and died. The results indicate that ketoconazole is a safe and effective drug for therapy in the treatment of paracoccidioidomycosis.

Adult↗
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Therapy of disseminated or pulmonary coccidioidomycosis with ketoconazole.

Oral therapy with ketoconazole for active disseminated or progressive pulmonary coccidioidomycosis was evaluated according to defined criteria of objective improvement for 39 patients, most of whom had received other antifungal chemotherapy. Minimal inhibitory concentrations of ketoconazole for isolates of Coccidioides immitis were below mean peak serum concentrations. Eighteen patients responded at all sites of disease, one patient failed to respond, and the others either are being evaluated or cannot be evaluated. Most patients who responded to therapy required more than three months of treatment before the response was clearly noted. Responses were seen with skin, soft tissue, skeletal, and pulmonary infection as well as other conditions. Reversions of cultures for C. immitis to negative and decreases in titers of complement-fixing antibody were common. One patient relapsed after a course of therapy of only four months. In general, patients with skin disease who responded required only 200 mg per day, whereas those with skeletal disease required 400 mg per day. Adverse effects were uncommon despite extensive monitoring and were generally limited to transient nausea (with vomiting in patients receiving 400 mg per day). The data show that ketoconazole appears to be a promising new drug for treatment of coccidioidomycosis.

Aged↗
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Initial experience in therapy for progressive mycoses with itraconazole, the first clinically studied triazole.

The search for antifungal drugs, particularly oral agents with a broad spectrum of activity, led to the study of itraconazole, a triazole. In vitro susceptibility testing suggested activity against a variety of fungal pathogens affecting humans. Pharmacokinetic studies indicated absorption after oral administration to patients, with prolonged serum concentrations and peak levels exceeding the in vitro inhibitory concentrations for most pathogens. Twenty-four patients have been enrolled in efficacy studies; two-thirds of these individuals had experienced a relapse after apparently successful therapy with other drugs, had failed to respond to other drug therapy, and/or had experienced intolerable side effects with other drugs. Fourteen patients have thus far responded to treatment with itraconazole; this group includes two persons each with coccidioidal pneumonia and adenopathy, pulmonary coccidioidomycosis, and dermatophytosis plus onychomycosis as well as one person each with coccidioidal epididymitis, adrenal histoplasmosis, head and neck histoplasmosis, cutaneous blastomycosis, oral-sinonasal alternariosis, chromoblastomycosis, invasive pulmonary aspergillosis with fungus ball, and onychomycosis. Five other patients have had partial responses to therapy, three have failed to respond, and two have been deemed unassessable. Drug toxicity has been limited in 211.8 patient-months of therapy. The results are encouraging and indicate that more extensive studies are warranted.

Adult↗
PubMedDate not supplied

Safety evaluation of chronic fluconazole therapy. Fluconazole Pan-American Study Group.

The possible adverse effects of chronic, high-dose fluconazole therapy are detailed from analysis of a multicenter, dose-escalating study of the therapy of invasive mycoses. Ninety-three adult patients were studied, 48 of these received > or = 6 months therapy and 20 received > or = 1 year. Fifty-eight patients received > or = 300 mg/day, and 7 received > or = 600 mg/day. One patient received 1,997 g over 86 months. Twenty-seven percent experienced possible symptomatic side effects, which resulted in 2 patients discontinuing therapy, and 42% had asymptomatic laboratory abnormalities, none of which were progressive. Headache, hair loss and anorexia were the most common symptoms experienced (each by 3% of patients), and eosinophilia and aspartate aminotransferase increases were the most common laboratory findings (12 and 10%, respectively). Fluconazole appears well tolerated and safe in these doses and durations.

Adult↗
PubMedDate not supplied

Coccidioidal antigen reactive CD4+ T-lymphocytes in the cerebrospinal fluid in coccidioides immitis meningitis.

CSF lymphocytes from patients with Coccidioides immitis meningitis exhibited a significant antigen-specific response to in vitro stimulation with C. immitis antigens. In some patients, lesser responses to control antigens (Candida and PPD) were also detected. Antigen-specific responses by CSF lymphocytes were seen early in the course of this disease as well as several years after patients had entered remission. When compared to CSF cells, the response of autologous peripheral blood mononuclear cells was similar but of a much smaller magnitude and at times undetectable. Fluorescence activated cell sorting revealed an increased percentage of CD3+ (T-cells), CD4+ (helper/inducer) and CD3+/HLA-DR+ (activated T-cell) cells in the CSF of C. immitis meningitis patients compared to their blood. Most of the antigen-specific proliferative response resided in the CD4+ lymphocyte subset. CSF T-cell proliferation assays may have a role in the diagnosis of C. immitis meningitis.

Adolescent↗