Millimeter-Wave Effects on Candida Albicans Cells

In preliminary measurements, Candida albicans cultures exposed to 1 kHz square-wave-modulated microwaves at 72 GHz exhibited a significantly reduced number of colony-forming units in comparison with nonirradiated controls. To study whether the same effect could also be caused by continuous-wave (CW) irradiation, sedimented cells were exposed to either 1 kHz square-wave-modulated or CW microwaves at 72 GHz, with the same peak power. CW-exposed cells showed a higher growth rate (about 25%), whereas a reduction of about 15% was seen in cells exposed to square-wave-modulated microwaves in comparison with sham-exposed controls.     

Etiological Significance of Candida Albicans in Otitis Externa

A study covering 79 patients (42 males, 37 females) of different age groups clinically diagnosed as otomycosis were investigated mycologically to elucidate the role of Candia albicans, an opportunistic polymorphic yeast, in otitis externa. C. albicans was diagnosed as the sole pathogen in two patients (1 male and 1 female) aged 18 and 20 years, respectively. The organism was repeatedly demonstrated in the aural specimens both by direct microscopy as well as culture isolation. Both the patients had unilateral otomycosis and used antibiotic solution and removed wax with wooden stick. The topical application of one per cent clotrimazole lotion showed good response both clinically as well as mycologically. The growing significance of opportunistic fungi emphasizes on comprehensive studies to establish the etiologic role in various clinical disorders in human and animal medicine.     

Genetic Analysis of Prototrophic Natural Variants of Candida Albicans

To facilitate genetic analysis of Candida albicans natural variants, we have isolated a dominant mycophenolic acid-resistant mutant. Mycophenolic acid-resistant auxotrophs were used to analyze prototrophic natural variants by spheroplast fusion. The fusion products were shown to be heterozygous for many of the parental chromosomes by molecular and genetic criteria. Using this approach, we have found that one type of morphologic variation is due to a recessive change and identified three dominant 5-fluorocytosine-resistant mutants. Rare fusion products express recessive parental markers. These exceptional progeny should be useful for linkage analysis and strain construction.     

Isogenic Strain Construction and Gene Mapping in Candida Albicans

Genetic manipulation of Candida albicans is constrained by its diploid genome and asexual life cycle. Recessive mutations are not expressed when heterozygous and undesired mutations introduced in the course of random mutagenesis cannot be removed by genetic back-crossing. To circumvent these problems, we developed a genotypic screen that permitted identification of a heterozygous recessive mutation at the URA3 locus. The mutation was introduced by targeted mutagenesis, homologous integration of transforming DNA, to avoid introduction of extraneous mutations. The ura3 mutation was rendered homozygous by a second round of transformation resulting in a Ura(-) strain otherwise isogenic with the parental clinical isolate. Subsequent mutation of the Ura(-) strain was achieved by targeted mutagenesis using the URA3 gene as a selectable marker. URA3 selection was used repeatedly for the sequential introduction of mutations by flanking the URA3 gene with direct repeats of the Salmonella typhimurium hisG gene. Spontaneous intrachromosomal recombination between the flanking repeats excised the URA3 gene restoring a Ura(-) phenotype. These Ura(-) segregants were selected on 5-fluoroorotic acid-containing medium and used in the next round of mutagenesis. To permit the physical mapping of disrupted genes, the 18-bp recognition sequence of the endonuclease I-SceI was incorporated into the hisG repeats. Site-specific cleavage of the chromosome with I-SceI revealed the position of the integrated sequences.     

Identification of Candida albicans using the chromogenic medium Albicans ID

The correct identification of the microrganism is the base for epidemiological studies and treatment of infections. The aim of our study was to evaluate the efficacy of the chromogenic media Albicans ID (bioMerieux, France) in the identification of Candida albicans. A total of 190 yeasts strains were evaluated in the study. A rate of 100% of all C. albicans (80) and Candida dubliniensis (five) strains exhibited blue color. Nevertheless, the blue color was also observed with cultures of Candida rugosa (3/5) and Candida tropicalis (3/17). Albicans ID cromogenic media presented specificity rate of 90% and positive and negative predictive values of 88% and 100%, respectively, in the identification of C. albicans.     

小鼠念珠菌感染模型和抗感染免疫

目前,临床相关的小鼠念珠菌感染疾病模型种类日益增多.与早期小鼠念珠菌感染模型相比,近期感染模型与临床上免疫抑制机会性念珠菌感染患者的感染方式、感染的发展进程、临床表现、靶器官临床病理组织学特征更相近.建立了特定免疫缺陷小鼠(如转基因/基因敲除小鼠等);感染源从白色念珠菌转向非白念珠菌(如近平滑念珠菌、光滑念珠菌等);感染方式从局部口腔-消化道感染逐步转变为血源性深部多器官组织感染.特定模型的建立更深入地探讨了宿主-念珠菌感染源之间相互的免疫机制.细胞介导的免疫反应在宿主抗念珠菌感染免疫反应中占主导,吞噬细胞直接杀伤真菌;细胞分化为Th1和Th2型细胞,分泌相关细胞因子进行免疫调控.体液免疫中一些保护性抗体也具有一定的保护作用.     

耐氟康唑的白假丝酵母菌主动外排机制初探

目的:了解对氟康唑耐药的白假丝酵母菌主动外排系统及主动外排基因CDR1的表达水平。方法:检测氟康唑敏感性和耐药性白假丝酵母菌对罗丹明6G主动外排情况,筛选出主动外排系统功能增强的菌株;采用Northern blot技术检测主动外排系统功能增强的菌株的CDR1基因的表达。结果:在由葡萄糖提供能量的体系中,5株耐药菌株外排罗丹明6G较敏感菌株明显增加,Northern blot发现其中4株CDR1基因表达水平升高。结论:耐氟康唑白假丝酵母菌主动外排基因CDR1表达升高。     

Repeated Use of Gal1 for Gene Disruption in Candida Albicans

A technique which has the potential to allow repeated use of the same selectable marker to create gene disruptions in Candida albicans has been developed. In this approach, originally described for Saccharomyces cerevisiae, the selectable marker is flanked by direct repeats. Mitotic recombination between these repeats leads to elimination of the selectable marker. A module in which the GALq1 gene is flanked by direct repeats of the bacterial CAT gene was constructed and used to disrupt one copy of the URA3 gene in a gal1 mutant. Gal- revertants were selected by plating on 2-deoxy-D-galactose (2DOG). The frequency of 2DOG-resistant colonies recovered was 20 times higher than that obtained with a similar construct not flanked by direct repeats. Of these, 20% had lost the GAL1 gene by recombination between the direct repeats. The GAL1 gene was used again to disrupt the remaining wild-type copy of the URA3 gene of one of these gal1 isolates, resulting in a stable ura3 mutant. This technique should be generally applicable to derive homozygous gene disruptions in this diploid organism.     

Relevance of Antigenicity of Candida Albicans Growth Phases to Diagnosis of Systemic Candidiasis

The antigenicity of the two growth phases of Candida albicans has been compared by using crossed immunoelectrophoresis and double-diffusion techniques. Qualitative and quantitative differences in antigenic composition between the phases have been revealed and moreover a specific mycelial antigenic component demonstrated.It is postulated that the use of specific mycelial antigens for routine diagnostic precipitin testing in patients with suspected systemic candidiasis would give more reliable results than at present obtained with yeast cell antigens.     

Candida Albicans: a molecular revolution built on lessons from budding yeast

Candida albicans is an opportunistic fungal pathogen that is found in the normal gastrointestinal flora of most healthy humans. However, in immunocompromised patients, blood-stream infections often cause death, despite the use of anti-fungal therapies. The recent completion of the C. albicans genome sequence, the availability of whole-genome microarrays and the development of tools for rapid molecular-genetic manipulations of the C. albicans genome are generating an explosion of information about the intriguing biology of this pathogen and about its mechanisms of virulence. They also reveal the extent of similarities and differences between C. albicans and its benign relative, Saccharomyces cerevisiae.     

Epidemiological analysis of oral surgery procedures

The epidemiological study was conducted to assess oral health of patients referred to the Department of Oral Surgery at Clinical Hospital Center in Rijeka. The distribution of particular diagnoses and surgical interventions in relation to frequency of occurrence was tested. The total of 1,268 patients aged from 5 to 89 years, both sexes, were included in the study. All the patients were treated under local anesthesia. The most common reason for referral to oral surgery was chronic periapical lesion (33.3%), followed by retained root (26.7%), impacted tooth (12.7%), and radicular cyst (8.3%). The majority of patients, residents of Rijeka city area, were treated for the diagnosis of adult periodontitis, while the radicular cysts and hypertrophy of the upper frenulum were more frequent referral diagnoses in patients coming from the areas around Rijeka. Extractions were performed more frequently in patients from Rijeka, while cystectomies with apicectomies and frenulectomies in other patients.     

Micafungin for Candida Albicans Pacemaker-Associated Endocarditis: A Case Report and Review of the Literature

We report on the treatment with micafungin of a pacemaker-associated endocarditis due to Candida albicans. Antifungal therapy was able to reduce vegetation size from 5 to 1 cm making possible the transvenous removal of the device without a high risk of pulmonary embolism. Noteworthy, a high micafungin concentration was documented into the lead vegetation (10 μg/g of vegetation tissue) and this may have contributed to the striking size reduction of vegetation.     

钛合金和钴铬合金表面白色念珠菌粘附的研究

目的比较钛合金(Ti-6Al-4V)和钴铬合金(Chromium-Cobaltalloy)表面白色念珠菌粘附能力的大小,研究表面粗糙度与细菌粘附的关系。方法将不同表面粗糙度的钛合金和钴铬合金试件进行白色念珠菌体外粘附试验,采用菌落形成计数法测定试件表面的细菌粘附量。结果各钛合金试件组的细菌粘附量均少于相同表面粗糙度的钴铬合金试件组,两种金属试件表面的细菌粘附量均随表面粗糙度的增大而增加。结论钛合金较钴铬合金更能减少由白色念珠菌引起的义齿性口炎等并发症,同时修复体表面严格的研磨抛光也能有效减少这些并发症。     

Prevalence and Exoenzyme Secretion by Candida Albicans Isolates from Oral and Vaginal Mucosas of HIV-Infected Women

A cross-sectional study was performed to evaluate the prevalence and the aetiology of forms of mucosal fungal infections of HIV-negative and HIV-positive women. Candida albicans was the predominate specie isolated from both groups of patients, with remarkable proportion of isolation from symptomatic women. All 239 C. albicans isolates, regardless of their source, showed activity of proteinase and phospholipase. It was verified that isolates with particularly higher levels of exoenzymes production were significantly more common in HIV-positive patients. However, isolates obtained from the HIV-positive patients in use of HAART, with protease inhibitor, presented lower levels of these exoenzymes, similar to the levels observed in the isolates from HIV-negative patients.     

Epidemiological investigations of chikungunya epidemic at Barsi, Maharashtra state, India

During the summer of 1973, an epidemic of Chikungunya broke out in Barsi, Sholapur district. Epidemiological investigations carried out during the decline phase revealed that all age groups and both sexes were involved with varying morbidity. The absence of previous immunity was demonstrated by a very high morbidity of 37.53 per cent for the whole town. The clinical picture encountered during the epidemic was quite characteristic of chikungunya. Besides gingivitis and epistaxis there were no frank haemorrhagic episodes. Reports about the presence of demonstrable rash varied. Except for one possible case, there was no mortality as a result of the epidemic. Results of the search for the index case are also described.     

口腔念珠菌基因多态性检测

目的检测正常人群口腔念珠菌基因型,以了解口腔念珠菌基因多态性。方法采集162例正常人群口腔样本,用念珠菌显色培养基(CHROM agar)进行菌种分离培养鉴定,用玉米Tween80培养基进行真菌孢子形态学检查鉴定,随机抽取45个菌株样本进行内含子转录间隔区(internal transcribed spacer region,ITS)序列检测,并比对同源性,建立进化树,观察菌株进化分支情况。结果分离培养出念珠菌菌株57株(57/162,35.2%),其中白色念珠菌(Candida albicans)36株(36/57,63.1%)。进行ITS序列检测的45个菌株申请GenBank序列注册号为FJ697166-GQ280292。结论正常人群口腔念珠菌基因具有多态性。     

Epidemiological investigation and typing of Candida glabrata clinical isolates by FTIR spectroscopy

Candida glabrata has emerged as one of the leading agents of fungal infections and strain typing is essential for epidemiological investigation that is generally achieved by molecular techniques. In this work, we studied twenty-nine C. glabrata strains isolated from different patients, using a phenotypic approach based on Fourier Transform Infrared (FTIR) spectroscopy, which has been in a previous study successfully applied as a rapid typing method for Candida albicans. A two-step procedure was used for the analysis. The first step included sixteen strains for the internal validation phase, which aimed at finding the spectral windows that would provide the best differentiation between strains. In this phase, hierarchical cluster analysis (HCA) carried out using three spectral windows (900-1200, 1540-1800, 2800-3000 cm(-1)) allowed to obtain the best classification, where each patient strains could be clustered together. A genotypic technique based on randomly amplified polymorphic DNA-analysis (RAPD) confirmed these results. In a second step, the external validation phase, thirteen other clinical strains of C. glabrata isolated from multiple sites in four ICU patients, were tested by FTIR spectroscopy. The analysis was based on the spectral regions previously found in the first step. HCA classification of the strains gave four groups, one group per patient. These results suggest that no inter-human transmission took place. This study shows the potential of FTIR approach for typing of C. glabrata with several advantages compared to other techniques. FTIR typing is fast, effective, and reagent free. Moreover, it is applicable to all micro-organisms and requires a small quantity of biomass.