Biomedical subjects

D A Stevens

Publications and source records attributed to D A Stevens.

At least 181 records · Page 10Linked to original sources

PubMed1994

Macrophage colony-stimulating factor induction of enhanced macrophage anticryptococcal activity: synergy with fluconazole for killing.

Enhancement of anticryptococcal activity in macrophages by macrophage colony-stimulating factor (M-CSF) and possible synergy between macrophages and fluconazole for killing of Cryptococcus neoformans were tested. M-CSF (48 h)-treated macrophages underwent dramatic morphologic changes and inhibited cryptococcal multiplication by 96% +/- 4%, which was greater (P < .001) than that of macrophages cultured in medium alone. M-CSF (5000 units/mL) induced optimal anticryptococcal activity but did not increase percentage of phagocytosis. NG-mono-methyl-L-arginine did not affect enhanced fungistatic activity. For a very fluconazole-sensitive isolate, fungistatic macrophages synergized with fungistatic doses of fluconazole for killing; for a less sensitive isolate, synergy was significant only when macrophages were activated with M-CSF or interferon-gamma plus lipopolysaccharide; for a fluconazole-resistant isolate, macrophages collaborated with fluconazole for additive fungistasis but not killing, and M-CSF-treated macrophages were significantly more fungistatic with fluconazole than were nonactivated macrophages.

Animals↗

PubMed1994

Support of Paracoccidioides brasiliensis multiplication by human monocytes or macrophages: inhibition by activated phagocytes.

The interaction of human monocytes or monocyte-derived macrophages and yeast-form Paracoccidioides brasiliensis was studied in vitro. Yeast cells were readily ingested by adherent monocytes or macrophages. Multiplication of P. brasiliensis, measured by growth as colony forming units (cfu) on a supplemented medium with good plating efficiency, was greater in monocyte co-cultures compared to the number of cfu obtained from complete tissue-culture medium (CTCM). Multiplication increased with time in macrophage co-cultures, e.g., from two-six-fold in 24 h to nine-fold in 72 h. Microscopic observations indicated that ingested yeast cells multiplied inside macrophages. When monocytes were treated with supernate cytokines (CK) from concanavalin-A-stimulated mononuclear cells, then co-cultured with P. brasiliensis, multiplication was significantly inhibited compared with control monocyte co-cultures. Treatment of macrophages--derived from monocytes by culture in vitro for 3 days--for a further 3 days with CK resulted in maximal inhibition of multiplication over the subsequent 72 h. Similarly, when monocyte-derived macrophages (after culture for 7 days) were treated for 3 days with recombinant human gamma-interferon (IFN; 300 U/ml) or CK they restricted multiplication of P. brasiliensis by 65% and 95%, respectively, compared with control macrophages. Antibody to IFN abrogated the effect of IFN or CK treatment. These findings show that ingested P. brasiliensis can multiply in human monocytes or macrophages and that this multiplication can be restricted by activated monocytes or macrophages.

Adult↗

PubMed1994

Cytokine treatment of central nervous system infection: efficacy of interleukin-12 alone and synergy with conventional antifungal therapy in experimental cryptococcosis.

Cell-mediated immune responses appear to be critical in the outcome of cryptococcosis. Interleukin-12 (IL-12) was studied for its potential use as a therapeutic agent because of its stimulation of natural killer cells and gamma interferon production by stimulated T cells and natural killer cells. Gamma interferon-activated macrophages are important in host resistance against cryptococcosis. In two separate studies, male BALB/c mice were infected intravenously with Cryptococcus neoformans. In the first study, mice received either no treatment, 5.0 mg of fluconazole alone per kg of body weight per day (by gavage twice daily), or IL-12 subcutaneously at 0.01, 0.1, or 1.0 microgram/day once daily (low-dose study) alone or in combination with 5.0 mg of fluconazole per kg/day. In a second study (high dose), the dosages of IL-12 used were 1.0, 2.5, or 5.0 micrograms/day. Therapy was given for 10 consecutive days, and the number of CFU of C. neoformans remaining in various organs was quantitated 1 or 2 days after administration of the last dose. In the low-dose study, IL-12 at 0.1 or 1.0 microgram reduced the level of brain infection by approximately 10-fold (P < 0.05) and IL-12 at 1.0 or 0.1 microgram/day enhanced the efficacy of fluconazole. In liver, both the efficacy of IL-12 alone (0.01 or 0.1 microgram; P < 0.05) and enhancement of the efficacy of fluconazole (P < 0.05) were seen. No efficacy of IL-12 was seen in spleens or lungs, although spleen weights increased fourfold in mice given 1.0 microgram of IL-12 per day. In the high-dose study, all IL-12 doses alone again reduced the levels of brain infection (5- to 8-fold; P < 0.05) when the two were given in combination. No overt toxicities were observed at any dose, and overall, 1.0 microgram of IL-12 per day was found to be the optimal dosage for reducing infection in the brain. To our knowledge, this is the first demonstration of the efficacy of cytokine therapy in systemic and particularly brain infections with C. neoformans. The stimulation of cell-mediated immunity represents a new approach to therapy and can enhance suboptimal antimicrobial chemotherapy. IL-12 should be considered for further study and for clinical trials. These studies suggest that other opportunistic central nervous system pathogens should also be investigated.

Animals↗

PubMed1994

Effect of macrophage colony-stimulating factor on anticryptococcal activity of bronchoalveolar macrophages: synergy with fluconazole for killing.

The anticryptococcal activity of murine bronchoalveolar macrophages (BAM) and their synergy with fluconazole (FCZ) was studied. BAM cultured with tissue culture medium for 48 to 72 h were fungicidal (24 to 39%) in a 3-h killing assay. However, net killing of Cryptococcus neoformans did not continue when culture time was extended to 24 h, although BAM were fungistatic (88 to 98%). Treatment with macrophage colony-stimulating factor (M-CSF; 5,000 U/ml, 48 h) did not significantly increase BAM killing of a low challenge dose in 3-h assays compared with control BAM. However, M-CSF-treated BAM were significantly more fungistatic against higher challenge doses in the 3-h assays. FCZ was not fungicidal at 5 micrograms/ml but was highly fungistatic (98 and 99% at 24 and 48 h, respectively). M-CSF-treated BAM acted synergistically with FCZ (2.5 micrograms/ml) for significantly greater killing than control BAM, 55% versus 20% and 96% versus 45% at 24 h and 48 h, respectively. Killing by M-CSF BAM and FCZ (5.0 micrograms/ml) was significantly (P < 0.01) greater than that by control BAM and FCZ at 48 h. These findings indicate an important collaborative role for BAM and FCZ in killing C. neoformans, and this is enhanced by M-CSF.

Animals↗

PubMed1994

Effect of in vivo macrophage colony-stimulating factor on fungistasis of bronchoalveolar and peritoneal macrophages against Cryptococcus neoformans.

Macrophage colony-stimulating factor (M-CSF) given subcutaneously at a dose of 2.5 mg/kg of body weight (4.75 x 10(6) U/kg) to CD-1 male mice 8 to 12 weeks old was found to enhance significantly the fungistasis of bronchoalveolar macrophages (BAM) against Cryptococcus neoformans. When M-CSF was given 1, 3, 7, 9, or 13 days before an ex vivo challenge with C. neoformans, fungistasis was increased (P ranged from < 0.05 to < 0.001) compared with that induced by control BAM. A maximum effect was seen by days 1 and 3 after administration of M-CSF. Twenty-one days after M-CSF, BAM did not produce significantly enhanced fungistasis. M-CSF also significantly enhances the fungistatic effect of peritoneal macrophages (PM) if given 1, 3, and 7 days prior to testing against C. neoformans in comparison with control PM (P ranged from < 0.05 to < 0.001). PM did not produce enhanced fungistasis 9 or 13 days after administration of M-CSF. These studies demonstrating in vivo enhancement of anticryptococcal activity of macrophages with M-CSF provide a rationale for in vivo use of M-CSF to enhance resistance to infection with C. neoformans.

Animals↗

PubMed1994

Saccharomyces cerevisiae virulence phenotype as determined with CD-1 mice is associated with the ability to grow at 42 degrees C and form pseudohyphae.

Saccharomyces cerevisiae isolates have been shown previously to exhibit a high degree of variation in their ability to proliferate and persist in CD-1 mice (K.V. Clemons, J.H. McCusker, R. W. Davis, and D.A. Stevens, J. Infect. Dis. 169:859-867, 1994). Isolate origin was not a firm predictor of virulence phenotype, since the virulence phenotypes of clinical and nonclinical isolates ranged from virulent to avirulent and from intermediate to avirulent, respectively. Therefore, it was important to determine if there was any association between putative virulence traits and virulence that might help explain the variation in virulence phenotypes. S. cerevisiae isolates spanning a range of virulence phenotypes in experimental infections were examined for putative virulence traits: the ability to grow at supraoptimal temperatures (42, 39, and 37 degrees C), gelatin liquefaction, casein utilization, and pseudohyphal formation. Gelatin liquefaction appeared to be unrelated to pseudohyphal formation on casein or to virulence. Significant differences in the ability to grow at 39 and 42 degrees C were observed when the virulent and intermediate classes were compared with the avirulent class. Less extreme but still significant differences in pseudohyphal formation were observed when the virulent and intermediate classes were compared with the avirulent class. Therefore, two virulence traits, similar to those identified in other pathogenic fungi, the ability to grow at elevated temperatures and pseudohyphal formation, have been identified in S. cerevisiae.

Animals↗

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↗

PubMed1994

Pulmonary mucormycosis presenting as an endobronchial lesion.

A 56-year-old diabetic man presented with left upper lobe collapse and postobstructive pneumonitis. Fiberoptic bronchoscopy revealed an endobronchial mass obstructing the left mainstem bronchus. The lesion resembled a bronchial adenoma; however, cytologic and histologic examination revealed invasive mucormycosis. The patient was treated with intravenous amphotericin B followed by endoscopic laser surgery that relieved the obstruction.

Adenoma↗

PubMed1993

High-dose weekly intravenous immunoglobulin to prevent infections in patients undergoing autologous bone marrow transplantation or severe myelosuppressive therapy. A study of the American Bone Marrow Transplant Group.

OBJECTIVE: To determine whether intravenous immunoglobulin (IVIG) prevents severe infections during autologous bone marrow transplantation or equivalent high-dose myelosuppressive therapy. DESIGN: Randomized, stratified, nonblinded study. SETTING: Three tertiary care university hospitals. PATIENTS: One hundred seventy patients entered the study; 82 received IVIG and 88 were untreated controls. The study groups were similar for parameters capable of influencing the likelihood of infection. INTERVENTIONS: Intravenous immunoglobulin was given weekly at a dose of 500 mg/kg body weight from the initiation of cytotoxic therapy to the resolution of neutropenia. MEASUREMENTS: The development of bloodstream or other clinically proven infection, platelet use, and the development of alloimmunity to platelet transfusion. RESULTS: Clinical infection, bacteremia, and fungemia occurred in 43%, 35%, and 6% of the IVIG-treated patients and in 44%, 34%, and 9% of the control patients. Gram-positive bacteremia and gram-negative bacteremia occurred in 28% and 11% of the IVIG group and in 23% and 13% of the control group. Death due to infection occurred in 4.9% of IVIG recipients and in 2.3% of controls. None of these observations was statistically significant (P > 0.2). Survival to hospital discharge was achieved in 86.6% of the IVIG group and in 96.6% of the control group. The survival difference (10%; 95% CI, 1.7% to 18.3%; P = 0.02) was due to a higher incidence of regimen-related toxic death in the IVIG-treated group. CONCLUSIONS: The use of IVIG did not prevent infection. Fewer deaths occurred among controls due to a higher incidence of fatal hepatic veno-occlusive disease in patients receiving IVIG.

Adolescent↗

PubMed1993

Ubiquinone systems of Coccidioides immitis, the causative agent of coccidioidomycosis.

The ubiquinone (coenzyme Q) systems of eleven strains of Coccidioides immitis were determined by high performance liquid chromatography (HPLC). The ubiquinone profile of the fungi was shown to be homogeneous: in all of the strains, ubiquinone-10 (Q-10) was demonstrated to be the major component, with Q-9 as a minor component. The results imply that the ubiquinone system may serve as an additional phenotypic criterion for identifying the fungus.

Coccidioides↗

PubMed1993

IL-4, IgE, and interferon-gamma production in pulmonary blastomycosis: comparison in mice untreated, immunized, or treated with an antifungal (SCH 39304).

The purpose of this study was to determine if there is a correlation between production of certain lymphokines in progressive blastomycosis in untreated mice, resistance to infection in immunized mice, and cure in antifungal triazole (SCH 39304)-treated mice. Infection was measured by colony-forming units of Blastomyces dermatitidis in lungs. Serum level of IgE was used as a marker for in vivo IL-4 activity. Serum IgE levels rose in untreated mice from 6 micrograms/ml at 3 weeks to 24 micrograms/ml by the fourth week as their infection progressed. This corresponded to a peak in vitro production of IL-4 (147 pg/ml) by antigen-stimulated spleen cells at Week 4. By contrast, there was an inverse relationship between serum IgE- and antigen-stimulated production of IFN-gamma in vitro, e.g., 80 U/ml at the third week and 4 U/ml at Week 4. In mice undergoing cure with SCH 39304, serum IgE decreased from 12 micrograms/ml at the third week to 2 micrograms/ml at Week 4. This correlated with a drop in IL-4 and an increase in IFN-gamma production in in vitro assays. As cure proceeded over the next 4 weeks, IgE and IFN-gamma measurements were near background levels. In immunized mice a low-grade chronic blastomycosis emerged after 3 weeks of infection. Chronic infection was associated with inverse cycles of elevated IgE in serum and IFN-gamma production as assayed in vitro. IL-4 production cycled directly with increased IgE levels in serum. Although spleen cells from untreated mice produced IFN-gamma and IL-4 when stimulated with antigen, they did not mount significant proliferative responses. By contrast, spleen cells and lymph node cells from immunized and SCH 39304-treated mice made good proliferative responses to antigen and this correlated with resistance and clearing of the infection, respectively. These data indicate that in pulmonary blastomycosis, serum IgE levels correlate directly with IL-4 and inversely with IFN-gamma production. Clearing of the infection by the antifungal agent SCH 39304 reduces lymphokine production to background levels but sensitizes lymphocytes for proliferative responses to antigen.

Animals↗

PubMed1993

Treatment of sporotrichosis with itraconazole. NIAID Mycoses Study Group.

PURPOSE: To describe the clinical presentation and outcomes of treatment with itraconazole in patients with sporotrichosis. METHODS: A culture for Sporothrix schenckii or compatible histopathology was required for inclusion in the study. Patients with both cutaneous and systemic sporotrichosis were treated. Patients received from 100 to 600 mg of itraconazole daily for 3 to 18 months. Patients were classified as responders or nonresponders. Responders were further classified as remaining on treatment, relapsed, or free of disease. Nonresponders included patients who failed to respond or progressed during treatment with itraconazole. RESULTS: Twenty-seven patients (mean age: 53 years) were treated with 30 courses of itraconazole. Diabetes mellitus and alcoholism were present in eight and seven patients, respectively. Sites of involvement included lymphocutaneous alone in 9 patients, articular/osseous in 15 (multifocal in 3), and lung in 3. Prior therapy was unsuccessful in 11 patients. Among the 30 courses, there were 25 responders and 5 nonresponders. All 5 nonresponders received at least 200 mg daily of itraconazole for durations that ranged from 6 to 18 months. Of the 25 responders, 7 relapsed 1 to 7 months after treatment durations of 6 to 18 months. Of the 7 who relapsed, 2 are responding to a second course. One responder was lost to follow-up after 10 months of treatment with itraconazole. Of the remaining 17 responders, 3 remain on treatment, and 14 are free of disease over follow-up durations of 6 to 42 months (mean: 17.6 months). Itraconazole was well tolerated with few side effects noted. CONCLUSIONS: These results document the efficacy of itraconazole in the treatment of cutaneous and systemic sporotrichosis.

Adult↗

PubMed1993

Fluconazole-resistant Candida in AIDS patients. Report of two cases.

Oropharyngeal candidiasis develops in up to 95% of patients with acquired immunodeficiency syndrome. Oral fluconazole is frequently prescribed for persons who are human immunodeficiency virus-seropositive as initial or suppressive therapy for oropharyngeal and esophageal candidiasis or as suppressive therapy for cryptococcal meningitis. We report two cases of oropharyngeal candidiasis, caused by Candida albicans, which developed in two patients with acquired immunodeficiency syndrome who had taken fluconazole for extended periods. In addition to the clinical resistance we observed, isolates of the organism appeared to be resistant in vitro to fluconazole and ketoconazole.

AIDS-Related Opportunistic Infections↗

PubMed1993

Ulcerative and plaque-like tracheobronchitis due to infection with Aspergillus in patients with AIDS.

Tracheobronchitis is an uncommon manifestation of infection due to Aspergillus species, occurring in < 7% of cases of pulmonary aspergillosis. At least 58 cases of invasive aspergillus tracheobronchitis have been described since 1962. We describe four patients with AIDS, all of whom were severely immunocompromised, who had ulcerative tracheobronchitis due to Aspergillus species demonstrated histologically. Three patients had received corticosteroids or were neutropenic at presentation. At bronchoscopy, three patients had some degree of diffuse tracheobronchitis, multiple ulcerative or "plaque-like" inflammatory lesions, and occasionally nodules involving the mainstem and segmental bronchi. The remaining patient had a single deep ulceration of the proximal trachea. Aspergillus was isolated from biopsy specimens from all four patients. There were varied degrees of invasion of the mucosa, submucosa, and cartilage on histological examination in three patients, one of whom had evidence of disseminated aspergillosis. Two patients subsequently developed pulmonary parenchymal disease due to Aspergillus. A review of aspergillus tracheobronchitis, including a discussion of airway disease in patients infected with human immunodeficiency virus, is presented.

AIDS-Related Opportunistic Infections↗

PubMed1993

Effect of hydroxypropyl-beta-cyclodextrin on efficacy of oral itraconazole in disseminated murine cryptococcosis.

The therapeutic efficacy of itraconazole solubilized in either the commonly used vehicle, polyethylene-glycol-200 (PEG) or hydroxypropyl beta-cyclodextrin was compared in a murine model of disseminated cryptococcosis. Itraconazole at doses of up to 120 mg/kg/day solubilized in PEG were found not to be effective. However, itraconazole at doses > or = 30 mg/kg/day solubilized in hydroxypropyl-beta-cyclodextrin markedly prolonged survival and a relationship between dose and survival was seen.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed1993

Therapeutic efficacy of a liposomal formulation of amphotericin B (AmBisome) against murine blastomycosis.

The efficacy of a liposomal amphotericin B preparation (AmBisome) and a deoxycholate suspension (Fungizone) were compared in a pulmonary model of murine blastomycosis. Male, four-week-old CD-1 mice were infected intranasally with 19,400 or 27,450 cfu of viable Blastomyces dermatitidis yeasts and intravenous therapy begun 4 days later. Groups of ten mice were given various dosages of Fungizone or AmBisome or were untreated. All treatments were given 3 times per week for 2 weeks. Deaths were recorded over 49 days and the number of viable yeasts in the lungs of survivors quantitated by viable counting. Therapy with 1.0 mg/kg/dose of Fungizone or 1.0, 3.0, 5.0, 7.5 or 20.0 mg/kg/dose of AmBisome were equivalent and prolonged survival over controls and lower dosages of each drug. No acute or chronic toxicities were observed with any regimen. Quantitation of residual numbers of yeasts in the lung showed that 70-100% of mice given 7.5 mg/kg or greater of AmBisome were free of infection and were superior to other regimens. At equivalent 1.0 mg/kg dosages Fungizone was superior to AmBisome. Although AmBisome was three-fold less active than Fungizone on a dosage basis, higher curative doses could be given that were not toxic. These data indicate that AmBisome should be further tested in other models and in clinical trials.

Amphotericin B↗

PubMed1993

Successful treatment of sporotrichosis with oral fluconazole: a report of three cases.

We report three cases of sporotrichosis successfully treated with oral fluconazole. A verrucous lesion on the toe was cured after 126 days, and a lesion on the left foot resolved after 91 days' treatment. A case of lymphangitic-type sporotrichosis required 174 days of treatment to achieve a cure, and a higher dose (400 mg daily) was necessary in this case. Any side-effects were insignificant. We conclude that this new bis-triazole compound can be successfully used as an alternative treatment for sporotrichosis when conventional drugs must be avoided.

Administration, Oral↗

PubMed1993

Effect of anti-IL-4, interferon-gamma and an antifungal triazole (SCH 42427) in paracoccidioidomycosis: correlation of IgE levels with outcome.

Paracoccidioidomycosis is characterized by depressed cellular but enhanced humoral immune responses, which suggests a Th2 type of response to infection. We investigated possible therapeutic roles for anti-IL-4, interferon-gamma (IFN-gamma) and/or SCH 42427 (SCH), a new triazole antifungal agent, and their effect on serum IgE levels in a murine model of chronic Paracoccidioides brasiliensis infection. BALB/c mice infected by the pulmonary route were studied with three programmes. The subacute model and one acute model experiment investigated cytokine secretion by lymph node cells (LNC), and in a second acute experiment mice were given anti-IL-4, IFN-gamma or nothing 24 h post infection, then killed at 4 weeks. In the chronic model, mice began treatment at 4 weeks post infection, receiving either SCH, IFN-gamma alone, SCH+IFN-gamma, or no treatment for 8 weeks. At 2-week intervals lung and spleen burdens of infection and serum polyclonal IgE levels were determined. In the subacute model (non-progressive infection), initially there was dual production of IL-4 and IFN-gamma by antigen-stimulated LNC. In the acute progressive infection model IL-4, but not IFN-gamma, was secreted. Anti-IL-4 treatment of the acute phase resulted in enhanced host resistance to infection, which correlated with decreased serum IgE. The chronic model, in which the in vivo efficacy of SCH against P. brasiliensis was shown, suggests possible synergy between immunomodulation and antimicrobial chemotherapy (IFN-gamma and SCH). Decreased organ burdens of infection in the chronic model after treatment with SCH, SCH plus IFN-gamma, or anti-IL-4 correlated with decreased serum IgE. These promising novel approaches to treatment of systemic fungal infections suggest a Th2 type of response to P. brasiliensis infection, which can be reversed with successful therapy.

Animals↗