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Biomedical subjects

B C Parker

Publications and source records attributed to B C Parker.

At least 37 records · Page 2Linked to original sources
PubMed1985

Cryoconite holes on glaciers.

Cryoconite holes are water-filled depressions on the surface of glaciers. They contain microbial communities and may contribute to glacial wastage and biological colonization of ice-free areas.

Antarctic Regions↗
PubMed1984

Response of an antarctic lake heterotrophic community to high dissolved oxygen.

The upper waters of Lake Hoare, Antarctica, contain dissolved oxygen at about three times the normal saturation (>/=42 mg liter). The response of the heterotrophic plankton community to this high dissolved oxygen was evaluated by the criteria of CFU and d-[U-C]glucose assimilated-respired. High dissolved oxygen was not inhibitory to d-[U-C]glucose assimilation-respiration compared with normal atmospheric dissolved oxygen in Lake Hoare water. The d-[U-C]glucose was assimilated and respired optimally at 12 degrees C in Lake Hoare. The d-[U-C]glucose assimilated-respired in the upper saturated atmospheric dissolved oxygen waters of Mountain Lake, Va., was inhibited in contrast to Lake Hoare (P < 0.05). CFU formation was inhibited in both lakes. CFU represent <1% of the fluorochrome-stained direct counts in Lake Hoare. Lake Hoare planktobacteria are smaller than the planktobacteria in Mountain Lake. ATP size fractionation revealed that 39% of the ATP biomass was <0.5 mum in Lake Hoare.

Journal Article↗
PubMed1984

Recovery and survival of nontuberculous mycobacteria under various growth and decontamination conditions.

The survival of microorganisms of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) complex was evaluated after various soil and water decontamination regimens. Survival was reduced by growing cells in natural waters compared with laboratory media and by inclusion of malachite green in media as an antifungal agent. Decontamination with benzalkonium chloride, while reducing survival significantly less than 1% NaOH, failed to eliminate many fungi. Recovery from soil was further reduced by transfer losses and by irreversible cell adsorption onto particulates.

Decontamination↗
PubMed1984

Epidemiology of infection by nontuberculous mycobacteria. V. Numbers in eastern United States soils and correlation with soil characteristics.

Organisms of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) group were recovered in significant numbers from 63 soil samples collected from the floodplains of 4 major rivers in the eastern United States: Hudson (NY), James (VA), Savannah (GA, SC), and Tombigbee (AL, MS). The mean numbers of M. avium-intracellulare, M. scrofulaceum, and MAIS-intermediate biovars recovered increased significantly from the Hudson to the James to the Tombigbee and Savannah soil samples, agreeing reasonably well with previous findings on MAIS distribution in eastern U.S. waters and with the geographic distribution of naval recruits reacting to PPD-B and PPD-G, which is higher in the southeastern United States. From the Savannah and Tombigbee rivers, soils were collected throughout their lengths. The number of total MAIS and biovars recovered from the different soil sites varied widely and showed no obvious trends. However, statistical analysis revealed a highly significant correlation between high numbers of MAIS recovered and high acidity of the soils. Other soil characteristics, such as high total organic matter, high conductivity, and reduced moisture, were only weakly, if at all, correlated with high MAIS numbers. Whereas the general distribution of MAIS in these soils of the Northeast (NY), mid-Atlantic (VA), and Southeast (GA, SC, AL, and MS) might explain the geographic distribution of the naval recruits reacting to PPD-B and PPD-G, the distribution of MAIS in soils along the stretches of the 2 southeastern rivers was not correlated with the county-by-county frequency of PPD-B reactive naval recruits in Georgia, South Carolina, Alabama, and Mississippi.

Humans↗
PubMed1983

Sensitivity of an oligotrophic lake planktonic bacterial community to oxygen stress.

Dissolved oxygen at approximately four times normal saturation (42 mg liter) inhibited the growth and metabolism of summer planktonic bacteria in the surface water of alpine oligotrophic Mountain Lake (Giles County, Va.). Data were derived from growth of CFU on membrane filters, d-[U-C]glucose incorporation into the extractable lipid of these CFU, and respiration and assimilation of d-[U-C]glucose by lake water samples. Statistically significant (alpha < 0.05) differences were not detected in either CFU or C incorporation in lipid when superoxide dismutase (30 U ml) or catalase (130 U ml) was added to the medium. Thus, exogenous oxygen by-products apparently are not responsible for the observed inhibition of growth and metabolism.

Journal Article↗
PubMed1983

Uric acid utilization by Mycobacterium intracellulare and Mycobacterium scrofulaceum isolates.

Forty-nine human and environmental isolates of Mycobacterium intracellulare and Mycobacterium scrofulaceum were tested for their ability to grow on uric acid and a number of its degradation products. Nearly all (88 to 90%) strains used uric acid or allantoin as a sole nitrogen source; fewer (47 to 69%) used allantoate, urea, or possibly ureidoglycollate. Enzymatic activities of one representative isolate demonstrated the existence of a uric acid degradation pathway resembling that in other aerobic microorganisms.

Humans↗
PubMed1983

Epidemiology of infection by nontuberculous mycobacteria. IV. Preferential aerosolization of Mycobacterium intracellulare from natural waters.

We report here the first laboratory studies simulating the conditions for natural aerosolization of Mycobacterium intracellulare and M. scrofulaceum and estimate the yields for this pathway of transfer of pathogenic mycobacteria from water to air; M. intracellulare and M. scrofulaceum were both concentrated in droplets ejected from cell suspensions of densities comparable to those found in natural freshwaters (100 to 2,000 colony-forming units per ml). The enrichment factor (defined as the concentration of cells per droplet volume divided by the concentration of cells in the bulk suspension per equivalent volume) for M. intracellulare isolates ranged from 68 to 15,000, with an average of 2,922; for M. scrofulaceum it ranged from 35 to 550, with an average of 177. One factor responsible for the greater aerosolization of M. intracellulare was their aggregation. However, after vortexing, M. intracellulare were still aerosolized more (enrichment factor, 325) than M. scrofulaceum. Increasing salt concentrations enriched the aerosolization of both species, but the number of organisms transferred from water to air did not increase proportionately because the salt decreased the droplet volume. Other waterborne pathogens such as Legionella pneumophila were also enriched and transferred from water to air, indicating that this pathway for possible infection of humans may also be significant for other respiratory diseases.

Aerosols↗
PubMed1980

Epidemiology of infection by nontuberculous mycobacteria. I. Geographic distribution in the eastern United States.

The nontuberculous mycobacterial group Mycobacterium avium-M. intracellular-M. scrofulaceum (MAIS) was isolated from 33% of the water samples collected from various aquatic environments in the southeastern United States. By contrast, only 20% of the water samples collected in the northeastern United States (New Jersey northward) yielded MAIS organisms. The most frequent recovery of MAIS organisms (37%) was from water samples with salinities from 0.1 to 1.9 g% (grams of NaCl/100 ml of sample). Other saprophytic slow- and rapid-growing nontuberculous mycobacteria were also isolated. The fewer MAIS organisms recovered from marine waters (20%) relative to those from freshwaters (37%) suggested that ocean water may not be a primary origin of these pathogens, although it still may be a source of infection. Our data implied a positive correlation between the frequency of persons reacting to MAIS antigens and the presence of these potential pathogens in the coastal region of the eastern United States.

Humans↗
PubMed1980

Epidemiology of infection by nontuberculous Mycobacteria. III. Isolation of potentially pathogenic mycobacteria from aerosols.

Nontuberculous mycobacteria (21 isolates), biochemically similar to those that are recovered from humans, were recovered from rainwater and from natural river waters and their aerosols in the area of Richmond, Virginia. Field experiments have confirmed the existence of a natural mechanism for the transfer of significant numbers of mycobacteria from water to air. These findings support the hypothesis that aerosolization of potentially pathogenic mycobacteria from waters of the southeastern United States may be a major pathway for human infection.

Aerosols↗
PubMedDate not supplied

Percutaneous transluminal angioplasty of the abdominal aorta.

PURPOSE: To determine the long-term results of percutaneous transluminal angioplasty (PTA) of focal infrarenal abdominal aortic stenoses. PATIENTS AND METHODS: Over a 10-year period, 15 focal infrarenal abdominal aortic stenoses were treated with PTA in 14 patients (13 women and one man; mean age, 53.2 years; range, 43-78 years). RESULTS: The initial technical success rate was 100%. Clinical patency, as defined by continued absence or improvement in symptoms after PTA, was achieved in 14 of the 15 angioplasty procedures (93%) with a mean duration of clinical follow-up of 4.3 years (range, 0.6-9.8 years) in the 14 patients. Long-term noninvasive follow-up demonstrated continued patency of the angioplasty site in 11 of 11 patients available for study. The mean ankle-arm index in these 11 patients was 0.95 (range, 0.9-1.0) at a mean follow-up of 4.8 years (range, 0.6-9.8 years). There was no significant morbidity or mortality associated with the angioplasty procedures. CONCLUSION: In view of the high degree of technical success and the excellent long-term patency, we believe that PTA should be considered a primary method of treatment in properly selected patients with focal abdominal aortic stenoses.

Angioplasty, Balloon↗
PubMedDate not supplied

Recent experience in the epidemiology of disease caused by atypical mycobacteria.

To obtain information on the epidemiology of mycobacteriosis, water and air samples collected along the East Coast of the United States were examined for mycobacteria. Mycobacterium avium-intracellulare-scrofulaceum (MAIS) were isolated from 25% of the water, samples, mostly those from South Carolina, Georgia, and the Gulf states. Mycobacterium kansasii and Mycobacterium marinum were not found, probably because of the detrimental effects of the NaOH used to decontaminate the samples. MAIS strains were found more often in estuaries than in fresh or ocean waters. The frequency of Mycobacterium intracellulare was relatively uniform along the entire coast, while Mycobacterium scrofulaceum predominated in the South. Only M. intracellulare was found in aerosol specimens, although both M. intracellulare and M. scrofulaceum were found in waters collected at the same sites.

Air Microbiology↗