Biomedical subjects
S Conti
Publications and source records attributed to S Conti.
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.
Panic disorder and suicidal ideation.
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Clinical significance of magnetic resonance imaging in preoperative planning for reconstruction of posterior tibial tendon ruptures.
A retrospective study of attenuated/ruptured posterior tibial tendons was conducted of all patients who underwent tendon reconstruction over a 4-year period. The study comprised 20 feet in 19 patients having an average age of 53.3 years, with an average follow-up of 2 years. Preoperative magnetic resonance images were taken and graded for assignment to one of three magnetic resonance imaging (MRI)-based groups. The surgical grade was determined intraoperatively based on a previously described classification scheme. No medical or rheumatologic conditions predisposing to failure could be identified. Failure was defined as postoperative progression of pain and deformity which required subsequent triple arthrodesis. There were six failures at an average of 14.7 months. Surgical evaluation was not correlated to outcome following reconstruction. MRI grading, however, was predictive of outcome. The superior sensitivity of MRI for detecting intramural degeneration in the posterior tibial tendon that was not obvious at surgery may explain why MRI is better than intraoperative tendon inspection for predicting the outcome of reconstructive surgery. Therefore, it may be helpful to obtain preoperative MRI when this particular reconstruction of the posterior tibial tendon is contemplated, since this provides the best measure of tendon integrity and appears to be the best predictor of clinical success after such surgery.
Clinical significance of holes in gloves for dental use: a spectrophotometric analysis.
The aim of this study on latex dental gloves was to establish whether there is any relationship between faults that are detected by filling with water and the entry of liquid into the gloves during use. Twenty-four gloves of different sizes were examined. Large and small holes randomly distributed on the index, middle, and ring fingers, were made in the gloves. The gloves were filled with water and squeezed to detect the amount of water escaping. A mass spectrophotometer was used with the same gloves to quantify the entry of an aqueous solution of potassium bichromate during work. The filling method was effective for revealing all faults in gloves, but it was not able to determine whether there would be fluid entry through the holes during work. While the size of the holes was not predictive for the amount of liquid entering the glove, adherence of the glove to the hand was. Holes of the same size allowed a greater entry of contaminated liquid in adherent gloves than in looser ones.
[The impact of AIDS on mortality in Italy].
Using the official mortality data, collected by ISTAT, and the data of the Italian Register of AIDS cases, in Istituto Superiore di Sanità, three arguments have been developed: 1) Study of causes according to which ISTAT could classify deaths from AIDS: the leading cause appears to be "Deficit of Cell Immunity" (I.C.D. 279.1). 2) Study of the under-estimation of official data with respect to those of the specific system. Under-estimation decreased over the years, reaching 20% in 1987 and 6% in 1988. 3) Analysis of the general mortality trend in all of Italy and in particular metropolitan areas, with a high concentration of cases, such as Rome and Milan; there is evidence of a possible influence of AIDS deaths on mortality of young age classes particularly notable among single males.
Hepatitis B virus infection in Cameroon: a seroepidemiological survey in city school children.
A pilot survey conducted in Cameroon comprising 702 children of primary school age revealed that 58.5% of the children were positive for at least one HBV marker. An overall HBsAg prevalence of 19.9% was observed. Both any HBV marker and HBsAg prevalences increased with age (P less than 0.01). Of the HBsAg-positive subjects, 28.4% were positive for HBV-DNA; none was positive for anti-HDV. There was no significant difference among sexes for either any HBV marker or for HBsAg prevalence. However, a significant difference by sex was found in the percentage ratio HBsAg+/and any marker + (41.0% in males against 28.2% in females; P less than 0.05). No significant difference with respect to the father's occupation and family size was observed. When the zone of location of school was taken into consideration it was observed that suburban school children had a higher prevalence of any HBV marker as compared to central town school children (73.9% vs. 56.6%; P less than 0.001). These results place Cameroon among countries of high endemicity for HBV. The results also indicate an early acquisition of infection, a high infectivity, and probably continuous infection even in the primary school ages.
Diagnostic potential of IgA coated Candida cells in mucous membrane candidiasis.
The significance of in vivo IgA coated yeast cells for the diagnosis of candidiasis of the oral and vaginal mucosal membranes was evaluated by direct immunofluorescence in 70 patients with or without clinical symptoms, shown to be positive for yeast growth in the cultural test. Most of the patients with clinically suspected candidiasis of the mucosal membranes gave positive results by serologic assays in contrast to the majority of symptomless patients. The diagnostic approach proved to be essentially consistent with the clinical signs, persistence of infection, response to antifungal therapy and quantitative cultural data.
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.
Characterological traits of recovered patients with panic disorder and agoraphobia.
Three self-rating personality inventories were administered to 33 patients who had recovered from panic disorder associated with agoraphobia and to 33 healthy subjects matched for sociodemographic variables. The personality inventories comprised the Tridimensional Personality Questionnaire (TPQ), which provides three major dimensions (novelty seeking, harm avoidance and reward dependence), the Anxiety Sensitivity Index (ASI) and the Emotional Inhibition Scale (EIS). Agoraphobic patients reported significantly more TPQ harm avoidance and anxiety sensitivity than controls. Although these findings might have been influenced by residual anxiety symptoms in panic-free patients and could also apply to patients with other anxiety disorders, they suggest that harm avoidance and anxiety sensitivity may be risk factors for developing agoraphobia and panic disorder. There may be overlap between this characterologic cluster and prodromal symptoms of panic disorder with agoraphobia, such as anxiety, phobias and hypochondriasis.
'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'.
Sexual lifestyles in injecting drug users in Italy: potential for HIV infection transmission. First Multicentre Study Group.
To better target efforts aimed at modifying sexual behaviour among injecting drug users (IDUs), we conducted a detailed analysis of sexual partners and practices reported by 1214 Italian heterosexual drug users during the period June 1985-June 1987. Females were more likely to have only drug-using partners (42.8% vs 17.1%), while males were more likely to have only non drug-using partners (50.5% vs 21.4%). Female drug users were more likely to report either one partner or greater than 10 partners, while males were more likely to report 2-10 partners. Nearly 90% of women with only drug-using partners had only one partner. Overall, 29% of women with only non drug-using partners reported that they always used condoms. This proportion increased to 65% among women with greater than 10 non drug-using partners. In Italy, male IDUs may play a greater role than female IDUs in sexual transmission of HIV infection to the heterosexual non drug-using partners.
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.
Evaluation of the permeability of latex gloves for use in dental practice.
The aim of this study was to evaluate the permeability of the disposable, nonsterile gloves used in dental practice. A visual inspection and a water-filling test were carried out on seven different brands of gloves. Only five of the seven makes analyzed showed a value of pinch marks statistically not different from 2% (the limit recommended by the American Society for Testing and Materials). Analysis of the gloves with holes revealed that only four makes showed a value statistically not different from 2%. Finally, only three of the seven makes analyzed had a number of defects statistically not different from 2%. It may therefore be stated that the average quality level currently available should be improved to guarantee a safer and more effective protection against oral pathogens in dental practice.
Drug use and HIV-1 infection: report from the Second Italian Multicenter Study.
A cross-sectional study was carried out in October 1988 among clients of public health centers in Italy that provide assistance for drug dependency. In addition to estimating the frequency of HIV-1 infection and of risk factors related to drug use, the study estimated the temporal gap between relevant events in the drug history of each subject. Forty-eight centers participated, representing 16 of the 20 Italian regions. Among 1,038/1,348 subjects, 395 (38%) were carriers of HIV-1 antibodies. Seropositivity was related to the length of heroin use (with the risk of being seropositive increasing by 1% for each month of use), to frequency of sharing injection equipment, and to sexual intercourse with a seropositive partner. Women were more likely to have shared injection equipment and to have engaged in sexual intercourse with seropositive partners. Most subjects began sharing injection equipment within a year of initiating drug use, and the median temporal gap between first drug use and first visit to a drug dependency center was 5 years. A high proportion of both seropositive (87%) and seronegative (74%) subjects reported the adoption of safer drug-use practices. In both groups many behavioral changes (38%) were reported to have been introduced before the initial HIV test. These findings confirm that efforts to reduce HIV infection among drug users in Italy will need to concentrate both on prevention of drug use and on early intervention to reduce high-risk behaviors.
Botryomyces caespitosus as an agent of cutaneous phaeohyphomycosis.
The second known case of a skin infection caused by Botryomyces caespitosus is reported. This case has made it possible to describe the characteristics of this fungus in vivo and to establish it as another agent of phaeohyphomycosis.