Biomedical subjects
G Morace
Publications and source records attributed to G Morace.
Anaerobic yeast killer systems.
The influence of anaerobic conditions on the expression of the killer phenomenon of several yeast isolates belonging to recognized killer systems coded by different genetic determinants (Pichia spp., Kluyveromyces lactis, Saccharomyces cerevisiae) was studied. Anaerobiosis influenced the activity of killer toxins from some individual isolates of the genera Pichia and Saccharomyces on sensitive strains of P. anomala, K. lactis and Candida albicans. However, no influence was detectable on a S. cerevisiae sensitive isolate. Thus, anaerobic conditions seem to interfere more with the metabolic process of sensitive strains than with toxin production by killer yeasts. The selection of a panel of killer yeasts, able to display their activity against reference sensitive yeast isolates under anaerobic conditions in a medium that favored the growth of anaerobes, allowed the use of the killer system to type Bacteroides fragilis isolates for epidemiological purposes.
Genomic studies on killer yeasts belonging to the genus Pichia.
Twenty-four species belonging to the genus Pichia were investigated using restriction fragment length polymorphism (RFLP) and Southern blot hybridization of their genomic DNA. Saccharomyces cerevisiae, Kluyveromyces lactis, Williopsis mrakii and Candida albicans were also included in this study. The RFLP patterns were obtained from digestion of yeast DNA with several restriction endonuclease enzymes, and showed various bands with different mobility; in most isolates, the more deeply stained bands were species-specific. This observation was confirmed by the results obtained from Southern blot hybridization of the EcoRI and XhoI RFLP patterns with P. anomala UCSC 25F DNA, digested with the same enzymes, used as probes. These bands are likely to be ribosomal DNA as shown by hybridization of digested DNA from unrelated yeast species (S. cerevisiae, K. lactis and C. albicans). However, one hybridized band, located at 3.9-4.1 Kb, seems to be peculiar to the Pichia species. Our study confirms the usefulness of molecular tools in studying genetic relatedness among yeasts.
Ultrastructural immunodetection of a Pichia anomala killer toxin: a preliminary study.
A monoclonal antibody (mAb KT4), produced against a Pichia anomala killer toxin, was used to study the secretion process of toxin producing cells. The indirect immunofluorescence assay, performed with large concentrations of mAb KT4, showed a homogeneous distribution of the epitope at the cell surface of the P anomala cells. When increasing dilutions of mAb KT4 were employed, a 'punctuated' labeling appeared on the yeast's cell wall which suggested a heterogeneous secretion of the killer toxin. Similar labeling was also observed by immunodetection on live yeast cells held in buffered suspension. These results confirmed that 'punctuated' labeling was not an artefact due to a distortion of the cell's shape by having been dried on glass slides. Indirect immunodetection was performed in electron microscopy on ultra-thin sections of cells embedded in Araldite resin. The labeling thus obtained showed both the presence of the epitope in the cytoplasm and its sensitivity to strong glutaraldehyde fixation. Indirect immunodetection, performed on ultra-thin frozen sections, showed a cytoplasmic and cell wall labelling. However, the amount of gold particles observed in the cell wall was too low to confirm the heterogeneous killer toxin secretion observed in immunofluorescence. In this case, killer cells were fixed with a low concentration of glutaraldehyde which preserved the structure of the epitope complementary with mAb KT4.
Onychomycosis as a possible origin of disseminated Fusarium solani infection in a patient with severe aplastic anemia.
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[The determination of myocardial necrosis in unstable angina by the immunoradiometric measurement of circulating myosin].
Ventricular myosin heavy chains serum levels are a new marker of myocardial necrosis. We have studied plasma levels of myosin in 30 patients with unstable angina, 30 patients with acute myocardial infarction and 25 healthy subjects. The myosin peak level was 317 +/- 101 microU/L in angina patients, 2510 +/- 433 microU/L in infarcted patients and 62.3 +/- 17 microU/L in the controls. In both groups, the increase in serum myosin was more marked in those with larger infarction and in those with more severe angina. These data suggest that the measurement of serum myosin can identify the presence of micronecrosis in patients with unstable angina, according to what has been found using other markers of myocellular necrosis.
Differential toxinogenesis in the genus Pichia detected by an anti-yeast killer toxin monoclonal antibody.
The differential toxinogenesis of 25 isolates belonging to species of the potential yeast killer genus Pichia that were previously classified in the genus Hansenula was comparatively demonstrated by two serologic techniques (indirect immunofluorescence and double immunodiffusion) by using a monoclonal antibody against a yeast killer toxin produced by a selected strain of Pichia anomala (UCSC 25F). The killer phenotypes of the Pichia isolates were evaluated by their ability to kill each other. The results, although of insufficient taxonomic value for a reliable separation of either species or genera, attest to the genomic heterogeneity for the killer character in the genus Pichia as well as the presumptive dual killer/sensitive identity for each single isolate.
An anthraquinone and three naphthopyrone derivatives from Cassia pudibunda.
Chemical examination of the methanolic extract of the roots of Cassia pudibunda led to isolation of the new rubrofusarin-6-O-beta-D-glucopyranoside, quinquangulin-6-O-beta- D-apiofuranosyl-(1----6)-O-beta-D-glucopyranoside, quinquangulin-6-O-beta-D-glucopyranoside and chrysophanol dimethyl ether. Moreover the known chrysophanol, physcion, cis-3,3',5,5'-tetrahydroxy-4-methoxystilbene, trans-3,3',5,5' -tetrahydroxy-4-methoxystilbene, and cassiaside B were identified. The antimicrobial activity of some of these compounds is also reported.
'Antibiobodies': antibiotic-like anti-idiotypic antibodies.
Pathogenic micro-organisms such as Candida albicans may be susceptible to the activity of antimicrobial products like yeast killer toxins due to the presence of specific cell wall receptors for these agents. Anti-idiotypic antibodies (anti-Ids) were produced that competed for these receptors with the yeast killer toxin of a strain of Pichia anomala. We report here that affinity chromatography purified anti-Ids may kill C. albicans cells in vitro which are susceptible to the activity of the yeast killer toxin, as well as P. anomala killer cells which are obviously immune to their own toxin despite possessing specific cell wall receptors which can be detected by indirect immunofluorescence with anti-Ids. We propose that these conceptually new antimicrobial immunoglobulins acting as antibiotics be called 'antibiobodies'.
In-vitro comparative activity of fluconazole and other antifungal agents against Blastoschizomyces capitatus.
Blastoschizomyces capitatus represents an emerging fungal pathogen in acute leukemia patients. The susceptibility to amphotericin B, 5-fluorocytosine, ketoconazole and fluconazole of nine clinical isolates was evaluated. A specific medium (high resolution medium) was used for testing fluconazole. This agent and 5-fluorocytosine were at least four- to eight-fold more active than amphotericin B and ketoconazole against all isolates but one.
In vitro susceptibility of 119 yeast isolates to fluconazole, 5-fluorocytosine, amphotericin B and ketoconazole.
The in vitro activity of fluconazole was tested against 13 yeast species (119 strains) isolated from clinical specimens during a 3-month period. For comparative purposes, three other antifungal compounds (5-fluorocytosine, amphotericin B and ketoconazole) were also tested. The tests were carried out using a microautomated method previously developed in our laboratory. The method allowed us to determine the minimum inhibitory concentration (MIC) of the four antifungal drugs used. For each of the drugs we utilized different media. The MIC ranges (mg/l) of fluconazole were: 0.04-12.5 for Candida albicans, 0.19-6.25 for Candida parapsilosis, 12.5-50 for Candida krusei, 0.04-100 for Candida tropicalis, 0.04- greater than 100 for Candida glabrata, 0.09- greater than 25 for Cryptococcus neoformans, 0.09-0.78 for Saccharomyces cerevisiae, 6.25- greater than 100 for Trichosporon beigelii and 0.09-0.19 for Blastoschizomyces capitatus (Trichosporon capitatum). The MIC value (mg/l) was 0.39 for Candida guilliermondii and Candida lusitaniae, greater than 100 for Cryptococcus laurentii and 0.09 for the 3 isolates of Torulopsis candida. These results were obtained using the medium recommended for in vitro testing of fluconazole (high-resolution medium) by Pfizer UK.
Interfaces of the yeast killer phenomenon.
A new prophylactic and therapeutic antimicrobial strategy based on a specific physiological target that is effectively used by killer yeasts in their natural ecological competition is theorized. The natural system exploited is the yeast killer phenomenon previously adopted as an epidemiological marker for intraspecific differentiation of opportunistic yeasts, hyphomycetes, and bacteria. Pathogenic microorganisms (Candida albicans) may be susceptible to the activity of yeast killer toxins due to the presence of specific cell wall receptors. On the basis of the idiotypic network, we report that antiidiotypic antibodies, produced against a monoclonal antibody bearing the receptor-like idiotype, are in vivo protecting animals immunized through idiotypic vaccination and in vitro mimicking the antimicrobial activity of yeast killer toxins, thus acting as antibiotics.
Detection by immunofluorescent anti-idiotypic antibodies of yeast killer toxin cell wall receptors of Candida albicans.
Yeast killer toxin cell wall receptors of Candida albicans were observed by indirect immunofluorescence using an affinity purified rabbit anti-idiotypic antiserum. The antiserum had been raised against a monoclonal antibody neutralizing the in vitro activity of a killer toxin produced by a selected strain of Hansenula anomala UCSC 25F. This simple procedure permitted the location of killer toxin cell wall receptors in various morphological phases of the yeast cells. The use of the indirect immunofluorescence technique with anti-idiotypic antibodies may have potential value in determining the occurrence of killer toxin receptors in other microbial systems.
Epidemiological and clinical aspects of mycoses in patients with AIDS-related pathologies.
Mycological, cultural and/or serological studies were performed on 98 patients hospitalized in the Department of Infectious Diseases of the Catholic University in Rome with diagnoses of acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC) diseases. The incidence of mycoses was evaluated by retrospectively analyzing the results of mycological examinations and comparing them with clinical manifestations. The presence of concomitant bacterial, viral and parasitic infections was also examined. For epidemiological purposes, the study was extended to include the biotyping of all yeasts isolated from patients hospitalized between September 1988 and February 1989 in the same Department. Antimycotic susceptibility was also determined for the first yeast isolate obtained from each of these patients. Oral candidiasis (50 cases) caused by Candida albicans was the most frequent mycosis, followed by esophageal candidiasis (13 cases) and cryptococcosis (6 cases). Four out of the 6 cryptococcosis patients had meningeal involvement. Systemic candidiasis (2 cases) and aspergillosis (1 case) were less common. Biotyping of yeasts isolated between September 1988 and February 1989 with the killer system revealed type 377 to be the most common among the C. albicans isolates. It represented 70% of all the yeasts isolated.
Production of yeast killer toxin in experimentally infected animals.
The ability of a killer yeast (Pichia anomala, UCSC 25F) to produce toxin in vivo was demonstrated, for the first time, in tissues of normal and immunosuppressed experimentally infected mice by means of a fluorescent antibody technique and a killer toxin specific monoclonal antibody. The possible significance of the findings is discussed.
Nosocomial outbreak of systemic candidosis associated with parenteral nutrition.
Eight patients in two surgical units developed systemic candidosis during a 40-day period from June 5 to July 13, 1987 (in five cases Candida albicans was identified). Three of them died. All cases belonged to a group of 27 patients receiving parenteral nutrition (PN), while among the 108 patients who did not receive PN, no cases were observed (p = .000001). Candida was cultured from two PN bags administered to the cases. A specialized nutrition nurse was responsible for the PN compounding and for maintaining administration sets in the two wards involved. An epidemiological investigation, in which 19 uninfected patients who had had PN were used as controls, showed no significant difference between cases and controls except that lipids were more frequently added to bags administered to cases (p = .0005). Furthermore, the bags administered to cases contained a higher average number of multidose constituents (p = .0008) when the comparison was focused on the two days before the onset of symptoms. Given the favorable medium provided by lipids, even a low level contamination of PN solutions during compounding and/or administration could have been responsible for the exposure of cases to multidose vials suggests, although not conclusively, that an extrinsic contamination occurred during compounding. Six isolates of C albicans were available from four cases. C albicans was cultured from the pharyngeal swabs of two physicians and three nurses, including the specialized nutrition nurse.
[The echocardiographic diagnosis of thromboembolism of the right heart].
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[Depression of the ST segment : pending problems].
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