Biomedical subjects

E Brummer

Publications and source records attributed to E Brummer.

At least 37 records · Page 2Linked to original sources

PubMed1998

Anticryptococcal activity of voriconazole against Cryptococcus neoformans var. gatti vs var. neoformans: comparison with fluconazole and effect of human serum.

Voriconazole (VCZ), a new wide-spectrum antifungal triazole currently in development, was tested for activity against Cryptococcus neoformans (CN) var. gattii and var. neoformans in RPMI-1640 (RPMI) or RPMI plus human serum. In RPMI VCZ was 10-fold more inhibitory than FCZ for both varieties of CN. In the presence of human serum neither VCZ nor FCZ had enhanced activity against CN var. gattii. By contrast, both VCZ and FCZ had significantly increased activity in the presence of serum against CN var. neoformans. The lack of serum-enhancing activity for VCZ or FCZ against CN var. gattii may reflect the in vivo situation and predict less efficacy in CN var. gattii infections.

Antifungal Agents↗

PubMed1998

Effect of granulocyte-macrophage colony-stimulating factor on candidacidal activity of neutrophils, monocytes or monocyte-derived macrophages and synergy with fluconazole.

The effect of in-vitro granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment of neutrophils, monocytes or monocyte-derived macrophages (MDM) on candidacidal activity was tested. Synergy of effector cells with fluconazole (FCZ) for enhanced killing was also investigated. Incubation of neutrophils with GM-CSF 0.67 microg/L plus Candida albicans Sh27 for 24 h significantly increased candidacidal activity (36% versus 74%). Synergy with FCZ for killing was also significantly increased from 93% to 97% when neutrophils were incubated with GM-CSF. Monocytes cultured with GM-CSF and C. albicans for 24 h had significantly increased fungistatic activity compared to controls and synergy with FCZ for killing was significantly enhanced from 40% to 59%. Monocytes cultured for 3 days with GM-CSF had increased fungistatic activity compared to control MDM and showed synergy with FCZ for significantly enhanced killing (46%) compared to control MDM (12%).

Antifungal Agents↗

PubMed1998

Activity of voriconazole, a new triazole, combined with neutrophils or monocytes against Candida albicans: effect of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor.

The antifungal activity of voriconazole (VCZ) was tested against Candida albicans in the absence or presence of polymorphonuclear neutrophils (PMN) or monocytes. In some experiments, VCZ was compared to fluconazole (FCZ). On a weight basis, VCZ was 10-fold more efficacious than FCZ against C. albicans Sh27. Against an FCZ-resistant isolate, VCZ at 1 microg/ml produced the same fungistasis as FCZ at 20 microg/ml. VCZ at 0.1 microg/ml collaborated with PMN for enhanced killing to the same extent as FCZ at 1.0 microg/ml. Granulocyte-colony-stimulating factor (G-CSF) enhanced the candidacidal activity of PMN, and it increased the collaboration of PMN with VCZ for killing. Granulocyte-macrophage (GM)-CSF also significantly enhanced both the killing by PMN and the collaboration of PMN with VCZ for killing. VCZ collaborated with GM-CSF-activated monocytes [corrected] for enhanced killing of C. albicans Sh27, and GM-CSF increased this collaboration. Taken together, these data show that VCZ is more potent than FCZ against C. albicans isolates, alone and in collaboration with PMN or monocytes for enhanced killing. In addition, G-CSF- or GM-CSF-activated PMN and monocytes have enhanced collaboration with VCZ compared to that of unstimulated phagocytes with VCZ.

Antifungal Agents↗

PubMed1998

Activity of voriconazole combined with neutrophils or monocytes against Aspergillus fumigatus: effects of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor.

Voriconazole (VCZ) was tested for antifungal activity against Aspergillus fumigatus hyphae alone or in combination with neutrophils or monocytes. Antifungal activity was measured as percent inhibition of hyphal growth in assays using the dye MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] or XTT [2, 3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxa nilide ]. With both assays, VCZ inhibited hyphal growth at concentrations of <1 microgram/ml and was almost as active as amphotericin B. VCZ (0.6 microgram/ml) was sporicidal, as was amphotericin B (0.4 microgram/ml). With both the MTT and XTT assays, neutrophils alone inhibited hyphae; when combined with VCZ, there was additive activity. Both granulocyte colony-stimulating factor- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-treated polymorphonuclear neutrophils (PMN) had enhanced inhibition of hyphal growth. Moreover, such treatment of PMN also enhanced the collaboration of PMN with VCZ. Monocytes inhibited hyphal growth. When VCZ was combined with monocytes or monocytes were treated with GM-CSF, inhibition was significantly increased, to similar levels. However, the combination of VCZ with GM-CSF treatment of monocytes did not significantly increase the high-level inhibition by monocytes with either agent alone.

Antifungal Agents↗

PubMed1998

Damage to yeast cells of Cryptococcus neoformans by voriconazole and fluconazole: a culture and microscopic study.

A systematic cultural, cytological and microscopic study of voriconazole (VCZ) and fluconazole (FCZ) damage to Cryptococcus neoformans over time was made. When haemocytometer counts were compared with colony-forming units (cfu) viability decreased with increased drug concentration and prolonged treatment time up to 48 h. Percentage viability by vital staining correlated with cfu. Concentrations of VCZ were found to be 10-fold more potent than FCZ. At 72 h, percentage viability increased in cultures with lower drug concentrations, indicating outgrowth of surviving yeast cells. Drug treatment resulted in a cytological change in a large percentage of yeast cells characterized by a large central vacuole easily observed microscopically. Vital staining showed that there was no direct relationship between cytological changes and non-viability. These novel findings add a new approach for studying the antifungal action of VCZ and FCZ against C. neoformans and provide a new perspective on their antifungal action.

Antifungal Agents↗

PubMed1997

Effect of iron on fluconazole activity against Candida albicans in presence of human serum or monocyte-derived macrophages.

Human serum, transferrin, and apotransferrin are known to profoundly inhibit the growth of Candida albicans by iron deprivation. On the other hand, iron overload (iron saturated transferrin) is a serious risk factor for candidiasis in newborn and in leukemic patients. We tested the efficacy of fluconazole and the previously demonstrated synergy of fluconazole and effector cells against C. albicans under iron overload conditions where efficacy might be diminished. We confirm that exogenous iron completely reversed the inhibitory effect of human serum and report that the efficacy of fluconazole against C. albicans was not significantly compromised in a 24 h assay system. Although exogenous iron inhibited fungistatic activity of monocyte-derived macrophages, it did not interfere with the synergistic candidacidal activity of fluconazole and monocyte-derived macrophages. In 72 h assays, where fluconazole had candidacidal activity, exogenous iron did not compromise efficacy of fluconazole, and fluconazole activity was often increased. These in vitro results suggest that effectiveness of fluconazole therapy would not be compromised in iron overload situations in vivo.

Antifungal Agents↗

PubMed1997

Effect of granulocyte colony-stimulating factor on the candidacidal activity of polymorphonuclear neutrophils and their collaboration with fluconazole.

The effect of granulocyte colony-stimulating factor (GCSF) treatment of polymorphonuclear neutrophils (PMN) in vitro was studied with respect to their candidacidal activity. The candidacidal activity of PMN was found to be significantly increased when they were pretreated with GCSF. Fluconazole (1 microg/ml) was found to be highly fungistatic (90%) for Candida albicans Sh27 and collaborated with PMN for significantly increased killing. Collaborative killing by PMN significantly increased when they were treated with GCSF before and after fungal exposure. The enhancing activities of GCSF required optimization of the GCSF dose and were thus inoculum and strain dependent.

Antifungal Agents↗

PubMed1997

Virulent isolates and mutants of Blastomyces in mice: a legacy for studies of pathogenesis.

This article provides information on the history of Blastomyces dermatitidis isolates and spontaneous mutants, the relationship with maintenance of cultures, and their virulence as quantified in murine models. Virulent isolates have been obtained from soil or from patients. Regardless of origin, mutants attenuated in virulence have sometimes arisen from storage as frozen yeast, frozen mycelia, or refrigerated yeast or serial passage in vitro at 35 degrees to 37 degrees C. Once virulence is lost, reversion to the virulent phenotype (even after serial passage in animals) has not been seen. These data, methods, and isolates provide a basis for future studies of virulence factors.

Animals↗

PubMed1996

Synergy of human neutrophils with fluconazole in killing Candida species.

The killing of Candida species by human neutrophils in a long-term 24-h assay and possible synergy with fluconazole (FCZ) for killing was investigated. The test medium (TM) consisted of RPMI-1640, penicillin and streptomycin (P/S), and 10% fresh autologous serum. TM alone was highly fungistatic for Candida species compared to TM without serum. When neutrophils were cocultured in TM with Candida species for 24 h the inoculum colony-forming units (CFU) were always significantly reduced (killing) by 58 to 99%. FCZ was tested over a range of 1-500 micrograms/ml, and though almost always fungistatic itself, it synergized with neutrophils for significantly increased killing of C. albicans (isolate Sh27) (P < 0.01) and C. albicans (isolate 94-20) (P < 0.05). Killing of non-albicans Candida species was so efficient in the absence of FCZ that demonstration of synergy with FCZ was difficult.

Antifungal Agents↗

PubMed1996

Study of the role of iron in the anticryptococcal activity of human serum and fluconazole.

Anticryptococcal activity of human serum and apotransferrin in RPMI 1640 was studied in vitro. The effects of varying concentrations of FeCl3 on this activity was investigated. Possible synergy of serum and apotransferrin with fluconazole was also measured. The fungistatic activity of human serum, whether lyophilized, stored at 4 degrees C, fresh frozen or purchased from commercial sources vs. Cryptococcus neoformans was comparable. There was no significant loss of fungistatic activity after freezing and thawing the serum up to 10 times. The fungistatic activity of human serum was similar when tested in different tissue culture media with the exception of Medium 199. The addition of apotransferrin (2.0 or 0.2 mg/ml) to RPMI 1640 had an inhibitory effect on cryptococcal growth. This effect was reversed by 20 microM, of FeCl3 at both apotransferrin concentrations. By contrast, addition of FeCl3 to human serum and RPMI 1640 did not reverse inhibition of growth. Fluconazole synergized with the human serum preparations described, but not with pooled commercial serum, for fungicidal activity. Synergistic activity of fluconazole and human serum was not affected by the addition of FeCl3. Apotransferrin did not show any synergistic fungicidal activity with fluconazole.

Antifungal Agents↗

PubMed1996

Treatment of Mycobacterium avium complex infection: do the results of in vitro susceptibility tests predict therapeutic outcome in humans?

The ability of various in vitro methods of antibiotic susceptibility testing to predict therapeutic outcome in patients infected with Mycobacterium avium complex (MAC) was evaluated. Pretreatment bloodstream MAC isolates from 38 patients with AIDS, previously treated in a randomized fashion with either ethambutol, rifampin, or clofazimine, were tested by three conventional methods using broth or agar, as well as by cocultivation with macrophages. The results obtained with each method were compared with the quantitatively determined bacteriologic response to the administration of the single agent in humans. None of the conventional in vitro susceptibility methods was predictive of therapeutic outcome, while the results of cocultivation with macrophages were of moderate predictive value. The positive predictive value of a response in humans based on a response in macrophages (defined by > or = to 1.0 log reduction in baseline colony counts after 5 days of treatment) was 74%. The negative predictive value was 82%.

AIDS-Related Opportunistic Infections↗

PubMed1996

Treatment of Myocardium avium complex infection: does the beige mouse model predict therapeutic outcome in humans?

To determine the predictive value of a standard murine model in the treatment of disseminated Myocardium avium complex (MAC) infection, beige mice were infected with MAC strains isolated from human immunodeficiency virus-infected patients and treated with the same antibiotic (ethambutol, clofazimine, or rifampin) that had been administered to the subject from whom that strain had been recovered. While ethambutol had the greatest bacteriologic efficacy in humans (mean decrease +/-SD, 1.0+/-0.5 log 10 cfu/mL of blood), clofazimine had the greatest bacteriostatic efficacy in mice (mean decrease +/- SD, 2.8 +/- 0.7 log(10) cfu/g of tissue). A linear correlation was not observed between bacteriostatic activity in mouse liver or spleen and the degree of bacteriologic response in humans (P > or = to .1). Odds ratios for a response in humans based on a bacteriologic response in mice were not significant for each agent (P > or = to .1, all cases).

AIDS-Related Opportunistic Infections↗

PubMed1996

Role of extended culture time on synergy of fluconazole and human monocyte-derived macrophages in clearing Candida albicans.

Possible enhanced candidacidal synergy of fluconazole and human monocyte-derived macrophages by extended culture time was studied. Synergistic candidacidal activity increased from 1 day to 3 days and was maximal at 6 days. Enhanced synergistic candidacidal activity at 144 h was observed over a 10-fold challenge dose range. Enhanced synergy with culture time was seen with fluconazole-susceptible and -resistant isolates of Candida albicans. These findings emphasize the importance of dosage and an adequate period of therapy.

Antifungal Agents↗

PubMed1995

Macrophage colony-stimulating factor (M-CSF) induction of enhanced anticryptococcal activity in human monocyte-derived macrophages: synergy with fluconazole for killing.

Induction of enhanced anticryptococcal activity in human monocyte-derived macrophages (HMM) by macrophage colony-stimulating factor (M-CSF) and possible synergy with fluconazole (FCZ) for killing of Cryptococcus neoformans (CN) was studied. Fungistasis by HMM cultured in medium for 3, 5, or 7 days was minimal, 0-17%. The fungistasis of HMM cocultured with M-CSF at 1000, 5000, or 20,000 U/ml for 3, 5, or 7 days was increased significantly (P < 0.02) at all study times and by all concentrations. The optimal M-CSF concentration for HMM treatment for enhanced fungistasis was 5000 U/ml for Day 3 (84%), whereas 1000 U/ml was sufficient with more prolonged HMM culture and M-CSF treatment (Days 5-7). The enhancement by M-CSF was seen with four different donors and three patient isolates of CN. FCZ at 5 micrograms/ml was fungicidal, 28 +/- 17% (n = 8). Killing by FCZ was enhanced by HMM treated with M-CSF 5000 or 20,000 U/ml for 5 days compared to control HMM, 58% (P = 0.001) and 60% (P = 0.002) vs 48%, respectively. This was also seen with HMM cultured with 1000 U/ml M-CSF for 7 days (P < 0.05). M-CSF also induced in HMM enhancement of fungistasis by lower, fungistatic, concentrations of FCZ. These results demonstrate enhancement of anticryptococcal activity by HMM treated with M-CSF and synergy with FCZ for inhibition and killing. These findings may provide a rationale for combined treatment of FCZ and M-CSF against cryptococcosis.

Cells, Cultured↗

PubMed1995

Induction of novel protein synthesis by opsonized Histoplasma capsulatum ingested by murine peritoneal macrophages.

It is known that Histoplasma capsulatum can resist the intraphagolysosomal environment and multiply inside macrophages. This resistance can be closely related to its pathogenicity. The mechanism of this resistance has been investigated, but it has not been clarified as yet. To learn about the metabolic condition of the yeast-form of H. capsulatum (isolates G217B and CDC 105) when ingested by macrophages, we investigated protein synthesis by ingested H. capsulatum with [35S]-methionine labeling. Cycloheximide at 5 to 10 micrograms/ml was used to preferentially inhibit macrophage uptake of [35S]-methionine without affecting H. capsulatum uptake. Protein synthesis by H. capsulatum in medium alone served as a positive control. The negative control consisted of macrophages with ingested heat-killed H. capsulatum. Analysis of cytosols with SDS-PAGE and fluorography disclosed that, respectively for G217B and CDC 105, ingested H. capsulatum synthesized 4 and 5 novel proteins, increased the synthesis of 9 and 17 proteins and decreased the synthesis of 9 and 10 constitutive proteins. Ten of these novel or increased proteins were apparently common to both strains. These metabolic changes in ingested H. capsulatum could reflect its adaptation to the intraphagolysosomal environment of macrophages and its ability to multiply there.

Adaptation, Biological↗

PubMed1995

In vivo and in vitro effects of macrophage colony-stimulating factor (M-CSF) on bronchoalveolar macrophages for antihistoplasmal activity.

The in vivo and in vitro effects of M-CSF on bronchoalveolar macrophages (BAM) activity against the intracellular fungal pathogen Histoplasma capsulatum (Hc) were studied. Three days after a single subcutaneous (s.c.) dose of M-CSF (2.5 mg/kg), enhanced ex vivo antifungal activity of BAM was measured. BAM from M-CSF-treated CD-1 mice significantly (P < 0.01) inhibited the intracellular multiplication of Hc yeast cells in 20 h assays compared to BAM from control mice. This effect was not observed at days 1, 7, 11 or 21 post-treatment. A dose of 5 mg/kg s.c., but not 1 mg/kg, induced similar antifungal activity in BAM by day 3. Peritoneal macrophages (PM) from M-CSF-treated mice did not have enhanced antifungal activity at days and doses tested. BAM could also be activated for antihistoplasmal activity by M-CSF in vitro. M-CSF at 10,000 U/ml for 24 h or 5000 U/ml for 48 h induced significant (P < 0.01) inhibition of intracellular multiplication of Hc. Interferon-gamma (IFN) plus lipopolysaccharide (LPS) activated BAM and PM in vitro to inhibit intracellular multiplication of Hc (P < 0.001); the antihistoplasmal activity was completely inhibited by NG-monomethyl L-arginine (N-MMA), indicating that an L-arginine-dependent nitric oxide-producing mechanism was operative. N-MMA could not inhibit the antihistoplasmal activity of BAM or PM activated by M-CSF in vitro. The mechanism by which M-CSF-activated macrophages inhibit intracellular multiplication of Hc remains to be determined.

Animals↗

PubMed1995

Synergy of fluconazole with human monocytes or monocyte-derived macrophages for killing of Candida species.

Possible synergy between fluconazole and monocyte-derived macrophages (MDM) for significant killing of Candida species and between fluconazole and monocytes for increased candidacidal activity were studied. Human serum in test medium (RPMI 1640 with 10% fresh autologous human serum) was highly fungistatic for Candida species. Fluconazole in test medium, even at high concentrations, was not fungicidal. Monocytes alone were fungicidal for all Candida species and synergized with fluconazole for increased killing of a fluconazole-sensitive and a fluconazole-resistant Candida albicans isolate. MDM obtained by culturing for 3 or 5 days were not significantly fungicidal for C. albicans but could synergize with fungistatic fluconazole for significant killing. MDM alone killed Candida krusei and Candida glabrata but did not synergize with fluconazole for significantly increased killing. These results, which demonstrate synergy of fluconazole and mononuclear phagocytes for killing, help explain the in vivo efficacy of fluconazole against candidiasis.

Antifungal Agents↗

PubMed1995

Killing of Histoplasma capsulatum by macrophage colony stimulating factor-treated human monocyte-derived macrophages: role for reactive oxygen intermediates.

The interaction of human macrophages with the yeast-form of Histoplasma capsulatum was studied. The use of culture and a short-term assay period instead of microscopy gave direct evidence of the fungicidal activity of human macrophages. The present study reports the novel finding of fungicidal activity of macrophages derived from monocytes in the presence of macrophage colony-stimulating-factor (MCSF). The induction of fungicidal activity by this cytokine was dose dependent. MCSF at 10,000 U/ml was optimal with 73(SD3)% killing. Inhibition of macrophage killing by superoxide dismutase (SOD), but not catalase (CAT) or N-monomethyl-L-arginine (NMMA), established the role of the superoxide anion in the killing mechanism. The fungistatic activity of MCSF-derived human macrophages in a 24-h assay was also dose dependent and was not inhibited by SOD, CAT or NMMA. MCSF at 10,000 U/ml produced optimal macrophage fungistatic activity, 34.6(SD4)%.

Arginine↗