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Biomedical subjects

A C Albers

Publications and source records attributed to A C Albers.

12 recordsLinked to original sources
PubMed1994

Effect of narrow, pulsed high voltages on bacterial viability.

BACKGROUND AND PURPOSE: High-voltage pulsed current (HVPC) has been used to promote the healing of decubitus ulcers and surgical wounds. The benefits of HVPC are thought to include an antimicrobial action. This study was undertaken to explore the development of an in vitro system for the systematic evaluation of the effects of HVPC. METHODS: Using agarose-based media, the system allows for examination of the direct effect of HVPC on microorganisms as well as exploration of the possible in situ generation of bacteriostatic or bactericidal factors by the action of HVPC on constituents of the media. The solid media also allow characterization of the spatial extent of the current's effects such as changes in temperature or pH. The system was used to examine the effects of HVPC on four different species of bacteria: Escherichia coli, Klebsiella, Pseudomonas aeruginosa, and Staphylococcus aureus. RESULTS: Both direct and indirect bactericidal effects were observed at either the positive or negative electrode, or both, for each of the organisms, although zones of inhibition varied. Temperature and pH were examined as possible mechanisms for the indirect effect. Temperature changes observed during the application of HVPC were minimal and did not contribute to the antimicrobial effect. Extreme pH changes did not appear to be the major cause of the indirect effect because the zones of inhibition observed were generally larger than the zones of extremely acid or basic pHs. CONCLUSION AND DISCUSSION: High-voltage pulsed current produced antimicrobial effects in this in vitro study. Additional studies are needed to elucidate the mechanisms and to determine whether the mechanisms occur in vivo.

Bacterial Infections↗
PubMed1983

Ascorbic acid inhibition of Campylobacter jejuni growth.

The inhibitory effect of ascorbic acid on Campylobacter jejuni is described. In vitro growth of clinical strains, as measured spectrophotometrically, was inhibited by 0.5 mg of freshly prepared L-ascorbic acid per ml. Alkaline-treated or aged L-ascorbic acid increased inhibition, as did copper; however, L-cysteine, L-cystine, and glutathione prevented inhibition. Biochemical analysis of the medium and cultures indicated that one or more of the oxidation products of L-ascorbic acid, e.g., L-dehydroascorbic acid or L-diketogulonic acid, were more effective inhibitors than was reduced L-ascorbic acid.

Ascorbic Acid↗
PubMed1983

Accuracy of calibrated-loop transfer.

The accuracy of the 0.001-ml calibrated platinum loop was tested by two methods: visible absorption spectroscopy and weight determinations. By both methods it was demonstrated that the volume of the loop delivery is related to the angle at which the loop is withdrawn from the solution being sampled and the diameter of the container, provided that the volume in the container is adequate to cover the loop. Vertical sampling from small-diameter containers (less than or equal to 7-mm inside diameter) delivered approximately 50% of 0.001 ml, and sampling at a 45 degree angle from larger containers (greater than or equal to 22-mm inside diameter) gave a delivery volume of greater than 150% of 0.001 ml, resulting in a threefold difference in the amount delivered and an error rate of +/- 50%.

Bacteriological Techniques↗
PubMed1983

Selective pigment medium for Streptococcus agalactiae.

Increased awareness of the importance of Streptococcus agalactiae (Group B streptococcus) in neonatal morbidity and mortality has demonstrated the need for a selective and differential primary plating medium. In this report we describe a selective pigment medium containing colistin and nalidixic acid that allows presumptive identification of S. agalactiae from the primary plate, even when specimens are polymicrobic. A preliminary study compared the value of three media for pigment production by 137 known S. agalactiae strains. This was followed by a clinical laboratory trial using the best of these pigment media at an obstetric hospital in which 581 specimens from neonates, female reproductive tracts, and urinary tracts were screened. Subsequent to the clinical laboratory trial, an epidemiological investigation using the selective pigment medium was conducted on a mother/infant population. Of the 1,331 specimens screened for S. agalactiae, 75 (5.6%) were positive on 5% sheep blood agar and 79 (5.9%) were positive on the selective pigment medium.

Adult↗
PubMed1982

Simple method for quantitation of viable mycoplasmas.

A rapid, simple, and inexpensive method for quantitation of viable mycoplasmas is described. Serial dilutions were made in sterile microtiter plates with standard microtiter equipment. The results were multiplied by a factor of 2.38 to obtain colony-forming units comparable to those obtained with the laborious glass pipette-tube dilution method.

Agar↗
PubMed1982

Group G streptococci: a review of the literature.

A review of the occurrence, general characteristics, and identification procedures for Group G streptococci is presented. Group G streptococci cause the same types of infection and have similar morphological characteristics as the other beta-hemolytic streptococci. If serological methods are used for identification, cross reactions may be seen between Group G and B streptococci, as they share a common antigenic determinant. Group G may also be misidentified as Group A streptococci with biochemical testing because at least 7% of Group G are sensitive to bacitracin. are sensitive to bacitracin. are sensitive to bacitracin.

Humans↗
PubMed1981

Inactivation of mycoplasmas by long-chain alcohols.

In this report, we describe the inhibitory activity of long-chain alcohols on the growth of Mycoplasma gallisepticum and Mycoplasma pneumoniae. Peak inhibition was recorded with saturated primary alcohols (64 microM) varying in chain length from 16 to 19 carbon atoms. The unsaturated alcohols (oleyl, linoleyl, and linolenyl) and the secondary alcohol (pentadecan-2-ol), when employed in the same test conditions, were considerably less effective growth inhibitors than the primary saturated alcohols. Stearic and palmitic acids were also ineffective as growth inhibitors of M. pneumoniae and M. gallisepticum at a 128 microM concentration. Because these antimycoplasma agents are fatty alcohols and cholesterol is known to be required for the growth of some mycoplasmas, additional cholesterol was added in an attempt to reverse the inhibition observed with these agents. Cholesterol at a 128 microM concentration did not significantly relieve the growth inhibition observed with stearyl alcohol at a 48 microM concentration. Mammalian cell cultures were found to be significantly more resistant to the effects of these inhibitory alcohols than were the mycoplasmas. Electron micrographs showed that inclusion of stearyl alcohol in the culture medium produced changes in the cellular morphology of the treated mycoplasmas.

Alcohols↗
PubMed1981

Bromcresol green dextrose broth for the presumptive identification of group B streptococci.

A 1 percent dextrose broth using bromcresol green as a pH indicator is described for the presumptive identification of group B streptococci. The results in the medium are read after 24 hr incubation at 36C as a color change. This medium was tested using 550 strains of streptococci belonging to groups A, B, C, D, and G. All of the group A strains were negative whereas all of the group B and Group D strains were positive. Thus, by using bacitracin susceptibility, esculin hydrolysis, and BCG dextrose broth, the presumptive identification of the frequently encountered streptococci can be accomplished.

Animals↗
PubMed1977

Relationship of K1 antigen to biotype in clinical isolates of Escherichia coli.

Two hundred and ninety-four isolates of Escherichia coli, including 105 from blood cultures, 94 from stools of hospital inpatients, and 96 from rectal cultures of healthy young adults, were biotyped by using the API-20E system and tested for the presence of K1 antigen. The overall frequency of K1 strains was 14.2% and was similar among the three sources. Forty-eight biotypes were observed, but two-thirds of all isolates, including two-thirds of the K1 strains, belonged to only five biotypes. Among the five commonest biotypes, the distribution of K1 strains was nonrandom, since 23 of the 27 K1 strains belonged to only two biotypes. Analysis of the O and H antigens of K1 strains indicated that this correlation of biotype with K1 antigen was due to a restricted number of serovars ("clones") that were repeatedly isolated from the population studied. These serovas included O18:K1:H7, O1:121:H6 and O16:K1:H6. Although a statistically significant correlation between biotype and K1 antigen was observed, the correlation was not sufficiently great to alow biotyping to be of significant predictive value as a marker for the K1 antigen.

Antigens, Bacterial↗