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Biomedical subjects

A W Anderson

Publications and source records attributed to A W Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1986

Interface corrosion in amalgam-to-amalgam and amalgam-to-nonprecious metal crown couplings.

This study examined the contact surface area in the coupling of a class II amalgam restoration with another class II amalgam restoration or with a stainless steel or nickel-chrome crown in 1% NaCl solution. The characterization of interfaces was carried out by using SEM and EDX microanalysis. The results indicate that the coupling of an amalgam-stainless steel crown and an amalgam-inconel crown in NaCl solution forms a deposit on the crown surfaces. This deposit contains all the constituents of corrodible phases of amalgam, including Zn. If amalgam restorations in adjoining teeth are contemplated, non-Zn-containing amalgam alloys of the same composition should be considered.

Chemical Phenomena↗
PubMed1986

Leiomyosarcoma of the rectum.

We have reported a case of leiomyosarcoma of the rectum. These tumors comprise 0.1% of all rectal tumors, with about 100 cases having been reported. Symptomatology is nonspecific; digital examination is the most effective method of detection. Local surgical excision is as effective as abdominoperineal resection.

Electrocoagulation↗
PubMed1984

Bacterial Symbionts in the Sugar Beet Root Maggot, Tetanops myopaeformis (von Röder).

Aerobic heterotrophic and facultative anaerobic bacteria were isolated from all developmental stages of the sugar beet root maggot, Tetanops myopaeformis (von Röder). Two distinct bacterial symbiotic relationships were observed. Serratia liquefaciens and Serratia marcescens were found to be associated with all developmental stages. Bacterial symbiont transmission occurred from one generation to the next. Symbionts were transferred from the male reproductive system to the female reproductive system, where both an internal infiltration of the egg chorion and an external smearing of the eggs occurred during oviposition. Pseudomonas maltophilia was found in association with the larval gut and the inner surface of the puparium. Electron microscopy of the inner puparial surface revealed symbionts within the chitinous wall. In vitro symbiont chitinase production was found, using both nephelometric (turbidimetric) and N-acetylglucosamine assays. A relationship appeared to exist between adult fly emergence and enzymatic chitin degradation of the puparium by the bacterial symbionts.

Journal Article↗
PubMed1984

Contamination of dental unit cooling water with oral microorganisms and its prevention.

Each time the handpiece turbine is stopped while the bur is still in the patient's mouth, almost 1 ml of microbe-laden oral fluids may be aspirated into the average dental unit water line by the retraction valve present in the dental unit. This fluid may contain an average in excess of 54,000 microorganisms per milliliter, including both facultative and obligate anaerobic bacteria of medium to high virulence. Other infectious agents including hepatitis, herpes, influenza, and other upper respiratory viruses may also be present. This germ-laden water may then be sprayed into the mouth of the next patient, possibly initiating an oral or upper respiratory tract infection. Sterilizing the handpiece between appointments, although of great significance in the prevention of disease transmission, will not totally eliminate the problem discussed here as almost 95% of the oral fluid aspirated into the dental unit went past the handpiece and into the handpiece cooling water line. Complete elimination of the retraction valve in the unit is the most effective means of solving this problem, but, with present dental unit designs, this may result in water dripping onto the patient. A viable alternative is the installation of a check valve (anti-retraction valve) downstream from the retraction valve. Installation of a check valve resulted in an almost 4,000-fold decrease in this contamination. The attachment of a check valve will have no effect on normal less virulent bacteria already present in tap water. These bacteria colonize the water lines of the dental unit and are then continually shed into the water in numbers often as high as 1,000,000 CFU/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Phase contrast microscopy of microbial aggregates in the gingival sulcus of Macaca mulatta. Subgingival plaque bacteria in macaca mulatta.

The objective of this study was to study the relationship of microbial aggregates in the subgingival crevice to changes in periodontal health in Macaca mulatta. The sample included 68 oral sites from 17 Rhesus monkeys of various ages. The periodontal health of each site was evaluated using Plaque and Gingival Indices and crevice depth measurement. The subgingival plaque samples were examined by phase contrast microscopy and recorded on 16 mm film. A Microbial Index was developed based on a qualitative estimate of the numbers of organisms, morphology of predominant organisms, and the presence or absence of motility. The Microbial Index was demonstrated to be simple in use and highly reproducible. The findings indicate that changes in the Microbial Index are consistent with tissue changes seen in the periodontal status in M. mulatta. From this preliminary study, the oral flora of adult M. mulatta appears to have sufficient similarities to human oral flora to be used as a microbial model for experimental periodontal disease research. Future studies to refine and confirm the validity of the Microbial Index are warranted. It may prove to be a useful tool to monitor the effect of various treatment modalities on the periodontal flora and to determine the presence or absence of active disease.

Animals↗
PubMed1981

Identification of a Growth Stimulant for Lactobacillus sanfrancisco.

A compound required for the luxuriant growth of Lactobacillus sanfrancisco in laboratory media was isolated from a freshly prepared yeast extract, purified, and characterized. The stimulant was identified as a small peptide with a molecular weight of approximately 1,065, containing aspartic acid, cysteine, glutamic acid, glycine, and lysine.

Journal Article↗
PubMed1979

Production of Glucose Isomerase by Streptomyces flavogriseus.

A microorganism that produces glucose isomerase was isolated from soil and identified as a strain of Streptomyces flavogriseus. The organism produced a large quantity of glucose isomerase when grown on straw hemicellulose, xylan, xylose, and H(2)SO(4) hydrolysate of ryegrass straw. The organism produced glucose isomerase both intra- and extra-cellularly. The highest level of intracellular glucose isomerase (3.5 U/ml) was obtained in about 36 h by a culture grown on straw hemicellulose; the extracellular enzyme (1.5 U/ml) appeared in cultures grown for about 72 h. About equal levels of enzyme were produced in cultures grown on straw hemicellulose, xylan, xylose, and H(2)SO(4) hydrolysate of straw, but production of the enzyme was drastically reduced when the organism was grown on other carbon sources. As a nitrogen source, corn steep liquor produced the best results. Soy flour extract, yeast extract, and various peptones also were adequate substrates for glucose isomerase production. Addition of Mg, Mn, or Fe to the growth medium significantly enhanced enzyme production. The organism, however, did not require Co, which is commonly required by microorganisms used in the production of glucose isomerase.

Journal Article↗
PubMed1979

Extraction of glucose isomerase from Streptomyces flavogriseus.

Cationic detergent (cetyltrimethylammonium bromide or cetylpyridinium chloride) treatment extracted almost the same amount of glucose isomerase from cells of Streptomyces flavogriseus as mechanical disruption (sonic oscillation or abrasive grinding). The specific activity of the enzyme extracted with cationic detergents was approximately 20% higher than that liberated by mechanical disruption.

Bacteriolysis↗
PubMed1979

Purification, Immobilization, and Some Properties of Glucose Isomerase from Streptomyces flavogriseus.

Glucose isomerase (EC 5.3.1.5) produced from Streptomyces flavogriseus was purified by fractionation with (NH(4))(2)SO(4) and chromatography on diethylaminoethyl (DEAE)-cellulose and DEAE-Sephadex A-50 columns. The purified enzyme was homogeneous as shown by ultracentrifugation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Benzyl DEAE-cellulose, triethylaminoethyl-cellulose, and DEAE-cellulose were effective in the immobilization of partially purified glucose isomerase. Several differences in properties were found between purified soluble enzyme, immobilized enzyme (DEAE-cellulose-glucose isomerase), and heat-treated whole cells. Glucose and xylose served as substrate for the enzyme. Whole cells had the highest K(m) values for glucose and xylose; the soluble enzyme had the lowest values. The optimum temperature for activity of the soluble and immobilized enzymes was 70 degrees C; that for whole cells was 75 degrees C. The pH optimum for the three enzyme preparations was 7.5. Magnesium ion or Co was required for enzyme activity; an addition effect resulted from the presence of both Mg and Co. The enzyme activity was inhibited by Hg, Ag, or Cu. The conversion ratio of the enzyme for isomerization was about 50%. The soluble and immobilized enzymes showed a greater heat stability than whole cells. The soluble enzyme was stable over a slightly wider pH (5.0 to 9.0) range than the immobilized enzyme and whole cells (pH 5.5 to 9.0). The molecular weight of the enzyme determined by the sedimentation equilibrium method was 171,000. A tetrameric structure for the enzyme was also indicated. After operating at 70 degrees C for 5 days, the remaining enzyme activity of the immobilized enzyme and whole cells, which were used for the continuous isomerization of glucose in a plug-flow type of column in the presence of Mg and Co, was 75 and 55%, respectively. Elimination of Co decreased operational stability.

Journal Article↗
PubMed1979

A new method of preparing insects for scanning electron microscopy.

Acidified 2,2-dimethoxypropane (DMP), used as an alternative to regular fixation and dehydration methods for insects, was found to be the only successful means of preparing the sugarbeet root maggot larva, Tetanops myopaeformis (Röder) (Diptera:Otitidae), for the scanning electron microscope. No morphological changes were evident when DMP treated sugarbeet root maggot adults were compared to fresh (unfixed) adults and glutaraldehyde-osmium tetroxide fixed adults. The method has been used with success on several gropus of insects. Acidified CMP is quickly hydrolyzed by water in tissue to acetone and methanol. DMP is advantageous in that it penetrates water impermeable cuticles rapidly and saves several steps and time in the fixation and dehydration process.

Animals↗
PubMed1978

Pilot-scale semisolid fermentation of straw.

Semisolid fermentation of ryegrass straw to increase its animal feed value was successfully performed on a pilot scale. The pilot plant, which could handle 100 kg of straw per batch, was designed so that all major operations could take place in one vessel. The straw was hydrolyzed at 121 degrees C for 30 min with 0.5 N H2SO4 (7:3 liquid:solid), treated with ammonia to raise the pH to 5.0, inoculated with Candida utilis, and fermented in a semisolid state (70% moisture). During fermentation the straw was held stationary with air blown up through it. Batch fermentation times were 12 to 29 h. Semisolid fermentation did not require agitation and supported abundant growth at 20 to 40 degrees C even at near zero oxygen tensions. Fermentation increased the protein content, crude fat content, and in vitro rumen digestibility of the straw.

Animal Feed↗
PubMed1976

Growth of Aureobasidium pullulans on straw hydrolysate.

Growth characteristics and cell properties of Aureobasidium (Pullularia) pullulans were studied. The organism grew well on an acid hydrolysate of ryegrass straw over a wide range of pH and temperature. The optimum temperature and pH for the growth of the organism were 32 degrees C and 5.5, respectively. A cell yield of 1.5 g/liter of straw hydrolysate was obtained. The dried cell mass contained 42.6% crude protein, 0.4% crude fat, and 6.4% nucleic acids. The essential amino acid profile of the microbial protein was comparable to that of Candida utilis. A rat feeding study indicated that the A. pullulans cells were not toxic and that the feed intake, weight gain, and protein efficiency ratio values were superior to those obtained with C. utilis. Once the question of mathogenicity is resolved, A. pullulans could be useful for production of single-cell protein from cellulosic wastes.

Animal Feed↗