PubMed Health⌕ Search

Biomedical subjects

P A Volz

Publications and source records attributed to P A Volz.

At least 19 recordsLinked to original sources
PubMed2001

Colony growth rates of microfungal isolates from the north and south facing slopes of Evolution Canyon, Mount Carmel, Israel, after irradiation at 10(6) rads 60Co.

Species of microfungi were isolated from both the north facing slope (NFS) and the south facing slope (SFS) of Evolution Canyon, Mount Carmel, Israel. They were examined for growth rates before and after exposure to 10(6) rads of cobalt 60 irradiation. Above 10(6) rads all growth ceased after 1 day following exposure.

Cobalt Radioisotopes↗
PubMed1998

Space flight micro-fungi after 27 years storage in water and in continuous culture.

Four species of micro-fungi were selected for study in the National Aeronautics and Space Administration (NASA) Apollo Microbial Ecology Evaluation Device (MEED) mycology experiments. Trichophyton terrestre, Rhodotorula rubra, Saccharomyces cerevisiae and Chaetomium globosum were selected from a series of preflight test fungi for the MEED mycology studies during the 2 years prior to the actual flight (Volz, 1971a, 1972b). Conidia of T. terrestre, ascospores of C. globosum and yeast cells of R. rubra and S. cerevisiae were suspended in sterile distilled water and loaded into wet and dry cuvettes for exposure to specific space flight parameters according to the filters built into the space flight hardware (Volz, 1971b). Living cells were found in the original inocula and phenotype water storage after 27 years. Colony cells were also examined after 27 years of continuous culture.

Chaetomium↗
PubMed1998

Macroscopic variations of microfungal isolates from Evolution Canyon, Lower Nahal Oren, Mount Carmel, Haifa, Israel.

Microfungi (eleven species), isolated from both the north facing slope (NFS) and the south facing slope (SFS) of Evolution Canyon, Lower Nahal Oren, Mt Carmel, Israel, were examined for growth rates before and after exposure to cobalt 60 irradiation. Growth rates, morphology, and sporulation varied for the same species according to isolates recovered from the NFS, SFS, and carbon sources. In addition, the Mucor haemalis sexual zygospore production was monitored.

Biological Evolution↗
PubMed1998

Pseudohyphal variations of yeasts exposed to specific space flight parameters.

Phenotypes of Saccharomyces cerevisiae and Rhodotorula rubra exposed to specific parameters of space flight, which were measured both quantitatively and qualitatively, produced variations in pseudohyphal formation. Both the length of the parent and branch psuedohyphal filaments varied according to specific wavelengths and energy levels of UV light exposures when phenotypic isolates were compared with the parent or ground control isolate of each yeast species.

Phenotype↗
PubMed1997

Cobalt 60 radiation and growth of eleven species of micro-fungi from Evolution Canyon, Lower Nahal Oren, Israel.

Eleven micro-fungal species isolated from both the north facing slope (NFS) and the south facing slope (SFS) of Evolution Canyon, Lower Nahal Oren, Israel, were examined for growth rates before and after exposure to 60Co irradiation. Species of Alternaria, Aspergillus, Humicola, Oidiodendron, and Staphylotrichum from SFS grew faster than the NFS isolates while Fusarium, Sordaria, and Stachybotrys grew at greater rates from the NFS than from the SFS. Mucor and Ulocladium isolates grew at the same rate from both SFS and NFS. The eleven isolates from each slope were next subjected to 60Co irradiation. At 40,000 rads exposure, Alternaria, Fusarium, and Stachybotrys grew more rapidly when isolated from the NFS, while Humicola and Staphylotrichum grew at a faster rate when isolated from the SFS. Aspergillus, Mucor, Sordaria, and Ulocladium from both the NFS and the SFS had relatively the same growth rate at 40,000 rads exposure. At 400,000 rads exposure, growth rates remained much the same for both the N and S exposed isolates as they were at 40,000 rads. Above 10(6) rads, growth ceased but recovery occurred at various times for individual isolates of the same species from opposing canyon slopes.

Alternaria↗
PubMed1997

Transmission of fungal spores in space and their conditions for survival: a review.

The transfer of fungal spores to suitable hosts or nutrient substrates frequently depends on spore discharge and aerial transport to transmit the species. Factors affecting spore translocation and travel have been evaluated mycologically and mathematically and are reviewed. Global disease spread and transmission monitoring are discussed.

Air Microbiology↗
PubMed1995

Apollo MEED mycology revisited and reviewed, including the Trichophyton terrestre keratinophilic growth at splashdown and 23 years after exposure to space parameters.

Keratinophilic Trichophyton terrestre conidia were exposed to selected parameters of space flight including 254, 280 and 300 nm UV light, full light and total darkness of space. Phenotypic isolates were grown on human hair collected from one source at years 1 and 23 after splashdown. The patterns of fungal growth on the hair, and the hair deterioration rates, were noted according to the space exposure. Growth and deterioration were consistent but slightly reduced at year 23.

Darkness↗
PubMed1992

Virulence and adhesive properties of serotypes A and B of Candida albicans isolated from paediatric burn patients.

The virulence and adhesive properties of 50 isolates of Candida albicans serotypes A and B collected over 6 years from 48 paediatric burn patients were examined to provide more detailed information about candidal pathogenesis in burn patients and to examine the relevance of the commonly used epithelial cell adhesion assay for determining fungal virulence. The isolates represented a fair distribution of serotypes (29 isolates were serotype A and 21 isolates were serotype B) and a total of 28 serotype-biotype combinations were found; 32% of the serotype-biotype combinations appeared only once, while 44% of the isolates showed similar biotype tests for two of three digits. Adhesion of the isolates to plastic and to buccal epithelial cells (BECs) was examined and compared after growth in a chemically defined medium. There were significant differences in the adhesion of individual isolates to plastic or BECs, but no correlation was found between biotype and adhesiveness. Serotype B isolates were found to be more adhesive to BECs (p less than 0.05) but not to plastic. There was no apparent correlation between candidal adhesiveness and site of isolation from these patients (autografts, blood, faeces, throat swabs, tracheal aspirates, wounds and intravenous catheters), although isolates from catheters were generally less adhesive to epithelial cells. Virulence in a systemic infection mouse model revealed that there were significant differences in virulence between isolates, but no correlation was found between virulence and the biotype, serotype or site of isolation. Similarly, no correlation was found between virulence and adhesiveness or cell-surface hydrophobicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Diversity of micro-fungi in an Antarctic dry valley.

The fungal microflora of a dry valley in Southern Victoria Land near McMurdo Sound, Antarctica, was investigated. Samples were collected from introduced objects such as a mummified penguin and spent chewing tobacco in addition to the sparse soil found in rock fissures, isolated moss colonies, shoreline deposit materials, CaCO3 precipitates, and microbial mat debris obtained from the frozen surface of the lake in the basin of Taylor Valley. Using conventional media and techniques, all collection sites yielded populations of yeasts and filamentous fungi. Water samples and live microbial mats from beneath the lake ice yielded species of fungi along with an abundance of bacteria.

Antarctic Regions↗
PubMed1991

Sparse diversity of potential pathogenic soil micro-fungi in the Ukraine.

Soil from steppe and garden reserves, and urban park and wharf regions in the Ukraine, U.S.S.R., were studied for keratinophilic as well as for other predominant micro-fungal species. Most of the fungi were nonpathogens, and potential skin infecting fungi were limited to Microsporum gypseum and Trichophyton ajelloi. Species diversity identified population variation between collection sites.

Fungi↗
PubMed1990

Mycology studies in space.

The postflight phase of the Apollo MEED mycology attempts to identify survival according to exposure to specific quantitative space flight factors, while the second phase of studies identifies qualitative change other than cell survival [57]. Initial changes incurred in space on a fungal cell can be monitored and further examined on return of the fungal species test system to Earth. The postflight studies present a better understanding of the space environmental influences on living cells and a more clear understanding of the fungal species under examination.

Fungi↗
PubMed1987

Mechanisms of association of Candida albicans with intestinal mucosa.

The association of Candida albicans with gastrointestinal (GI) mucosal surfaces was studied in vitro and in vivo. The caecal mucosal surfaces from antibiotic-treated and untreated control mice challenged orally with C. albicans revealed that large numbers of C. albicans were associated with the intestinal epithelium of antibiotic-treated mice but not with that of the control mice that possessed an indigenous wall-associated bacterial flora. Moreover, Candida cells only penetrated deep into the mucosa of animals in which the ecology of the intestinal microflora had been disrupted. In mice given antibiotics, C. albicans was associated with the mucosa of all areas of the GI tract; the caecal mucosa had the most associated Candida, whereas the stomach and small intestine had very few associated yeasts. Further examination of caecal mucosa from antibiotic-treated mice showed that C. albicans associated with the mucosa by at least five distinct mechanisms. These included: adhesion to epithelium, adhesion to mucus, co-adhesion to adherent fungi, co-adhesion to adherent bacteria, and entrapment in the mucous gel overlying the epithelium. The cell-surface hydrophobicity of C. albicans also was examined and found not to play a role in Candida adhesion to intestinal mucosa. The predominant association mechanisms appeared to be entrapment in the mucous gel, and adhesion to mucus and the epithelium. The ecological and pathological significance of co-adhesion by C. albicans to attached organisms is unclear but it may be important in the initiation of mucosal lesions.

Animals↗
PubMed1985

Effect of various antibiotics on gastrointestinal colonization and dissemination by Candida albicans.

Mice were treated orally with various antibiotics to determine which members of the indigenous intestinal microflora normally suppress Candida albicans colonization and dissemination from the gastrointestinal (GI) tract. The mice were given penicillin, clindamycin, vancomycin, erythromycin, or gentamicin for 3 days, and then challenged orally with C. albicans. Penicillin, clindamycin, and vancomycin, but not gentamicin or erythromycin, decreased the total anaerobic bacterial populations in the animals ceca, and increased the enteric bacilli population levels. All three of the former antibiotics allowed C. albicans to proliferate in the gut and, subsequently, disseminate from the GI tract to visceral organs. The ability of C. albicans to associate with intestinal mucosal surfaces was also tested. It was found that antibiotics which reduced anaerobic population levels, but not enteric bacilli or aerobes, also predisposed animals to mucosal association by C. albicans. It is suggested that the strictly anaerobic bacterial populations which predominate in the gut ecosystem are responsible for the inhibition of C. albicans adhesion, colonization and dissemination from the GI tract.

Animals↗
PubMed1985

Ecology of Candida albicans gut colonization: inhibition of Candida adhesion, colonization, and dissemination from the gastrointestinal tract by bacterial antagonism.

Antibiotic-treated and untreated Syrian hamsters were inoculated intragastrically with Candida albicans to determine whether C. albicans could opportunistically colonize the gastrointestinal tract and disseminate to visceral organs. Antibiotic treatment decreased the total population levels of the indigenous bacterial flora and predisposed hamsters to gastrointestinal overgrowth and subsequent systemic dissemination by C. albicans in 86% of the animals. Both control hamsters not given antibiotics and antibiotic-treated animals reconventionalized with an indigenous microflora showed significantly lower gut populations of C. albicans, and C. albicans organisms were cultured from the visceral organs of 0 and 10% of the animals, respectively. Conversely, non-antibiotic-treated hamsters inoculated repeatedly with C. albicans had high numbers of C. albicans in the gut, and viable C. albicans was recovered from the visceral organs of 53% of the animals. Examination of the mucosal surfaces from test and control animals indicated further that animals which contained a complex indigenous microflora had significantly lower numbers of C. albicans associated with their gut walls than did antibiotic-treated animals. The ability of C. albicans to associate with intestinal mucosal surfaces also was tested by an in vitro adhesion assay. The results indicate that the indigenous microflora reduced the mucosal association of C. albicans by forming a dense layer of bacteria in the mucus gel, out-competing yeast cells for adhesion sites, and producing inhibitor substances (possibly volatile fatty acids, secondary bile acids, or both) that reduced C. albicans adhesion. It is suggested, therefore, that the indigenous intestinal microflora suppresses C. albicans colonization and dissemination from the gut by inhibiting Candida-mucosal association and reducing C. albicans population levels in the gut.

Adhesiveness↗
PubMed1984

Evaluation of a portable ultrasonoscope in assessing the body composition of college-age women.

Subcutaneous fat tissue thickness was measured ultrasonically on 66 females between the ages of 18-26 yr by using a portable ultrasonoscope and by skinfold caliper. Measurements were obtained at seven sites: triceps, biceps, subscapula, suprailiac, abdomen, calf, and thigh. In addition, body density (Db) was measured by the underwater weighing technique. Mean Db was 1.0458 gm X cc-1, corresponding to a percent fat of 22.8% (range = 11.3-35.8%). Correlations between ultrasonic and skinfold measurements were significant (P less than 0.05) at all sites. The highest was noted at the suprailiac (r = 0.86) and the lowest was at the thigh (r = 0.75). Test-retest reliability for ultrasonic measurements, taken on separate days, ranged from r = 0.87 at the triceps to r = 0.99 at the biceps. Four significant regression equations for predicting Db were developed, two utilized skinfolds and two utilized ultrasonic measurements of tissue thickness. The equation with the greatest multiple correlation (R = 0.80) utilized the suprailiac, subscapula, and thigh skinfolds. The equation using ultrasonic measurements taken at the suprailiac and thigh sites demonstrated a multiple correlation of R = 0.78. This instrument is a reliable, portable, and non-invasive alternative to the skinfold caliper in obtaining field measurements of body composition.

Adipose Tissue↗
PubMed1983

Dissemination of yeasts after gastrointestinal inoculation in antibiotic-treated mice.

Mice pretreated with antibiotics were inoculated intragastrically with different yeast isolates to determine whether the resulting disruption of the normal flora ecology would allow certain fungi to colonize and disseminate from the gastrointestinal tract. Antibiotic treatment decreased the total population levels of the indigenous bacterial flora, and predisposed mice to gastrointestinal overgrowth and subsequent dissemination by Candida albicans, C. parapsilosis, C. pseudotropicalis, C. tropicalis, and Torulopsis glabrata. A clinical isolate of Rhodotorula rubra, on the other hand, was unable to maintain a stable population in the gut of similar mice and could not be isolated from systemic organs. Control animals not receiving antibiotic therapy, challenged with C. albicans, showed significantly lower gut population levels of yeasts, and Candida organisms could not be grown from visceral organs. It is suggested that suppression of fungi within the gastrointestinal tract by members of the normal bacterial flora may be an important mechanism whereby fungi are confined to the alimentary tract.

Animals↗
PubMed1982

Gastrointestinal inoculation of Sporothrix schenckii in mice.

Antibiotic-decontaminated and untreated conventional mice were inoculated intragastrically with 10(7) viable cells of Sporothrix schenckii to compare the incidence of gastrointestinal (GI) colonization. In control mice, S. schenckii was completely eliminated from the GI tract by 12 h post-inoculation. Antibiotic-treated mice also failed to become colonized with this fungus, however, higher population levels of Sporothrix cells remained in the GI tract for a longer period of time before being eliminated. The ability of S. schenckii to disseminate from the lumen of the bowel to infect other organs was also tested. Results indicate that the gastrointestinal tract is not a portal of entry into the host for S. schenckii.

Animals↗