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Biomedical subjects

D L Stewart

Publications and source records attributed to D L Stewart.

At least 55 records · Page 3Linked to original sources
PubMed1991

Attitudes toward condom use and AIDS among patients from an urban family practice center.

As part of an effort to better educate patients about using condoms, a survey was done to assess the sexual practices, attitudes toward acquired immunodeficiency syndrome (AIDS) and condom use by patients who visit an urban family practice center. A self-administered questionnaire was given to 126 patients of whom the majority were black and single. Seventeen percent indicated they had sex with more than one person in the 3 months before the survey. Within the last 5 years, 10% had sex with an intravenous drug abuser, and 6% with someone of the same sex. Fifty percent believed that condoms decrease sexual pleasure for men and 31% thought condoms made sex inconvenient. Twenty-seven percent of those surveyed believed that a man's penis may be too large for a condom and 18% believed that uncircumcised men could not use condoms. Forty-five percent believed they should be screened for human immune deficiency virus exposure. The results highlight attitudes and beliefs that may function as barriers to condom use and should be addressed when encouraging condom use with this population.

Acquired Immunodeficiency Syndrome↗
PubMed1989

New technique for stabilizing umbilical artery catheters in very low birthweight infants.

The securing of umbilical artery catheters (UACs) with tape bridges has been associated with significant dermal complications in the very low birthweight neonate. We describe a new technique for UAC stabilization using an anchoring adhesive tape applied directly to the catheter, which is in turn sutured to the cord. This technique provides a very satisfactory method of UAC stabilization and avoids skin complications associated with the standard methods.

Bandages↗
PubMed1987

Solubilization of Leonardite by an Extracellular Fraction from Coriolus versicolor.

Coriolus versicolor has previously been shown to degrade leonardite, an oxidized form of lignite. An extracellular fraction containing protein purified from a C. versicolor culture solubilized leonardite in vitro. Expression of the activity did not require the presence of leonardite and appeared during idiophase. During ion-exchange and gel filtration column chromatography, leonardite-biosolubilizing activity eluted with syringaldazine oxidase activity and with protein, as measured by A(280) and the biuret protein assay. Syringaldazine is a substrate of the polyphenol oxidase formed by C. versicolor. Comparison of leonardite-biosolubilizing activity with the effects of chelators and surface-active agents on leonardite showed that biosolubilization was not due to either surfactant or chelating ability. Heat treatment of the preparation at 60 degrees C for 30 min significantly reduced both syringaldazine oxidase and leonardite-biosolubilizing activities. Cyanide, azide, and thioglycolate, which are known inhibitors of syringaldazine oxidase activity of C. versicolor, also inhibited leonardite biosolubilization. From these data, we conclude that the purified protein fraction from C. versicolor contains a syringaldazine oxidase activity that participates in leonardite biosolubilization by enzymatic action.

Journal Article↗
PubMed1985

Upper gastrointestinal endoscopy--how far does the endoscope go?

Two adult-size endoscopes (Olympus GIF-K2 and ACMI TX-8) were compared for extent of duodenal intubation by the endoscopist's estimate of location and x-ray position in 55 patients. The endoscopes were not different in duodenal position when separately analyzed for the endoscopist's estimate or x-ray location. Combining the results for both endoscopes showed the endoscopist's estimate to differ significantly from x-ray location in 47% of patients (p = 0.02). When incorrect, the endoscopist overestimated 62% of the time and underestimated 38% of the time. X-ray evaluation of insertion depth confirmed that the second portion of the duodenum was reached in 96%, third portion in 51%, and fourth portion or beyond in 38% of patients. We conclude that fluoroscopic confirmation may be necessary when endoscopically assessing distal duodenal segments for pathology.

Adult↗
PubMed1984

Microbial mutagenicity of isomeric two-, three-, and four-ring amino polycyclic aromatic hydrocarbons.

The isomers of various two-, three-, and four-ring amino polycyclic aromatic hydrocarbons were tested for mutagenic activity using a microbial plate incorporation test with four Salmonella typhimurium strains (TA98, TA100, TA1535, and TA1537). All compounds were assayed with an S9 metabolic activating enzyme system. The two-ring compounds were tested only with TA98. All were weakly mutagenic (1-10 rev/micrograms) except 2-aminobiphenyl, which was not mutagenic under these test conditions. All except two of the 13 fused three-ring compounds (aminofluorenes, aminoanthracenes, and aminophenanthrenes) were active frame shift mutagens; only the aminophenanthrenes were active base-pair mutagens. The potency of this group of isomeric compounds ranged from moderately (approximately 20 rev/microgram) to strongly (greater than 5,000 rev/microgram) mutagenic. As a group, the pericondensed four-ring amino compounds were the most mutagenic of the three groups tested. All of the aminofluoranthene and aminopyrene isomers showed significant mutagenic activity with TA98, TA100, and TA1537. In general, the mutagenic potency of the amino polycyclic aromatic compounds tested was highly dependent on the structural position of the amino group.

Animals↗
PubMed1984

Comparison of colon cleansing methods in preparation for colonoscopy.

Colonoscopy cleansing regimens were evaluated in 197 patients randomized in two study phases to one of four methods: group 1 (64 patients), 3-day clear liquid diet; group 2 (40 patients), 3-day minimum-residue diet; group 3 (44 patients), 1-day minimum-residue diet; group 4 (49 patients), Golytely. Groups 1-3 also received laxatives and enemas before colonoscopy. Physician assessment by endoscopists unaware of the method of colon cleansing favored group 4 (p less than 0.001), with good to excellent preparations achieved in 69% of group 1, 80% of groups 2 and 3, and 92% of group 4. Group 4 patients also experienced less abdominal distress (p less than 0.01). Breath hydrogen and methane levels were measured in groups 3 and 4 both before and after preparation. The decrease in pre- to postprep levels of hydrogen and methane were not significantly different between the groups and postprep gas concentrations were below combustible levels in both groups. There were no clinically significant differences between the four groups for any of the other measured hematologic or biochemical parameters. It is concluded that Golytely is a safe, effective method of colon cleansing, well tolerated by patients.

Adult↗
PubMed1983

Microbial mutagenicity of 3- and 4-ring polycyclic aromatic sulfur heterocycles.

The stable isomers of 3- and 4-ring polycyclic aromatic sulfur heterocycles were tested for mutagenicity in the Ames standard plate incorporation test and a liquid pre-incubation modification of the Ames test. Of the 4 three-ring compounds tested, only naphtho[1,2-b]thiophene was mutagenic. Of the four-ring compounds, 7 of 13 were mutagenic in the standard Ames or pre-incubation Ames test. The highest activity for the 4-ring compounds was observed for phenanthrol[3,4-b]thiophene, a compound of approximately the same mutagenic potency in the Ames test as benzo[a]pyrene. The other active 4-ring compounds were of considerable less mutagenic potency than phenanthrol[3,4-b]thiophene. Mutagenicity for two of the 4-ring aromatic thiophenes could only be detected in the liquid pre-incubation Ames test. Salmonella typhimurium TA100 was the most sensitive strain to mutagenesis by these compounds, followed by TA98. All mutagenesis was indirect, requiring metabolic activation.

Animals↗
PubMed1981

The effects of nitrous acid on the mutagenicity of two coal liquids and their genetically active chemical fractions.

The Ames/Salmonella assay was used to determine the effect of nitrous acid on the mutagenicity of solvent refined coal (SRC) distillates and distillate fractions. The SRC materials consisted of the higher-molecular-weight, high-boiling distillates, the process solvent (PS) and heavy distillate (HD), and also included the basic tar and neutral tar chemical fractions derived from these 2 distillates. Nitrosation products of each of the SRC materials were less mutagenic than the distillates of distillate fractions from which they were derived (untreated materials); in most cases they were less than 10% as mutagenic as that observed in the starting materials. The mutagenicity of the SRC materials after nitrous acid treatment was direct-acting, whereas all mutagenicity associated with the untreated SRC materials was indirect and required metabolic activation for expression in the Ames assay system.

Amines↗
PubMed1979

The effects of cooling to 5 degrees C and freezing and thawing on the ultrastructure of bull spermatozoa.

Semen from 6 bulls was examined under the transmission electron microscope immediately after collection, after dilution and cooling to 5 degrees C and after freezing and thawing. Conception rates were determined following artificial insemination of the frozen and thawed semen. Dilution and cooling to 5 degrees C caused acrosomal swelling in about 50% of the spermatozoa. Subsequent freezing and thawing caused considerable ultrastructural changes to the acrosomes (disruption of the plasma and outer acrosomal membranes and dispersion of the acrosomal contents) and middle pieces (breakage of the plasma membrane and a reduction in the electron density of the mitochondrial matrix) of a high proportion of spermatozoa. The average non-return rate following insemination of semen from 5 of the bulls was 61.6% and higher (P greater than 0.001) than for the sixth bull (15%). Although this difference in semen viability was also demonstrated in the structural studies (acrosome, P greater than 0.05: middle piece, P greater than 0.001), more work is required to assess the relationship between structure and function of spermatozoa.

Animals↗