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Biomedical subjects

R B Simpson

Publications and source records attributed to R B Simpson.

63 records · Page 4Linked to original sources
PubMed1974

Partition of fatty acids.

The partition ratios of radioactive fatty acids between n-heptane and a physiological buffer at 37 degrees C were measured. The fatty acids included the saturated acids with an even number of carbons from 10 to 18 and the unsaturated acids oleic, linoleic, and linolenic. In addition, the partition ratios of decanoate, myristate, and palmitate were determined over a wide pH range. Any single plot of partition ratio vs. aqueous concentration of an acid gave a nearly straight line, a finding consistent with very little association in the aqueous phase. In the case of the acids with 16 and 18 carbon atoms, however, comparison of the constants calculated from these plots with the assumption of no aqueous phase association revealed several inconsistencies. These inconsistencies cannot be resolved completely by assuming the existence of fatty acid association in the aqueous solution. We believe that at least some of the deviations are due to the presence of trace quantities of radioactive impurities in the labeled fatty acids. For example, purification of a sample of supposedly pure [1-(14)C]myristate by a series of solvent extractions increased the partition ratio by a factor of 1.5. Although all of the observations cannot be explained by this interpretation, we believe that our studies suggest that there is no appreciable association of fatty acids under the usual physiological conditions.

Alkanes↗
PubMedDate not supplied

Thimerosal dependent agglutination, a newly described blood bank problem.

A number of ABO grouping, Rh typing, antibody screening, and antibody identification problems are associated with chemicals in blood bank reagents. We describe a newly discovered agglutination phenomenon due to a thimerosal (Merthiolate)-dependent agglutinin found in the serum of a normal blood donor. Thimerosal is used as a preservative in several low-ionic strength reagents. This agglutination phenomenon is detected only in test systems (low-ionic-strength, albumin, saline, ficin treated test cells) in which test cells are incubated in the presence of thimerosal. Agglutination does not occur in the absence of thimerosal. The thimerosal-dependent agglutinin behaves like an IgG IgG autoantibody. There is no evidence that the thimerosal-dependent agglutinin is responsible for increased red cell destruction.

Adult↗
PubMedDate not supplied

Thimerosal-dependent agglutination complicating the serologic evaluation for unexpected antibodies.

Thimerosal (merthiolate) is a preservative present in several low-ionic-strength blood bank reagents. Thimerosal-dependent panagglutinins were found in the serum of a hospitalized patient during serologic testing for unexpected red cell antibodies. The agglutinins behaved like a mixture of IgG and IgM and reacted with all red cells tested. Once the true nature of the serum panagglutinins was determined, blood bank reagents free of thimerosol were used, and no further serologic problems were encountered. Agglutination of this type should be considered whenever sera appear to contain panagglutinins and thimerosal is present in the test system.

Aged↗
PubMedDate not supplied

Self-administered nitrous oxide analgesia for pediatric fracture reductions.

We prospectively studied the efficacy and safety of self-administered nitrous oxide analgesia for 54 children undergoing closed reductions of fractures in the emergency department. No child was excluded from entry into the study because of fracture type. Nitrous oxide was the sole source of analgesia. The average Children's Hospital of Eastern Ontario pain score (CHEOPS) rated by the emergency medicine physician observing the reduction was 9.1 (range 6-13). Ninety-one percent of children obtained an analgesic effect; however, 46% of children had a CHEOPS score of > or = 10, indicating significant pain. A statistically significantly higher proportion of failures using nitrous-oxide analgesia occurred in patients with completely displaced radius/ulna fractures (p = 0.027). No complications such as vomiting, respiratory depression, or a change in oxygen saturation resulted from the use of nitrous oxide.

Adolescent↗
PubMedDate not supplied

Detection of bacteria in equine synovial fluid by use of the polymerase chain reaction.

Equine synovial fluid aliquots were inoculated with Salmonella enteritidis, Escherichia coli, Actinobacillus equuli, Staphylococcus aureus, and Streptococcus zooepidemicus to obtain approximate concentrations of 1000, 100, 10, and 1 colony forming U/mL. Synovial fluid aliquots were also inoculated with an unquantitated inoculum of Bacteroides fragilis and Clostridium perfringens. Inoculated synovial fluid was incubated in trypticase-soy broth or Columbia broth for approximately 12 hours. Then aliquots were removed for DNA extraction and polymerase chain reaction (PCR) analysis for detection of a 531 base-pair segment of bacterial DNA corresponding to a region of the 16S ribosomal gene. Duplicate samples of inoculated synovial fluid were prepared for microbial culture. Bacteria were detected in all samples inoculated with bacteria but not in control synovial fluid samples. Under experimental conditions there was no difference between microbial culture and PCR analyses for detection of bacteria. Experimentally, PCR was able to detect bacteria in synovial fluid within 24 hours of inoculation.

Actinobacillus↗
PubMedDate not supplied

Evaluation of skin bacterial flora before and after aseptic preparation of clipped and nonclipped arthrocentesis sites in horses.

OBJECTIVE: This study evaluates skin bacterial flora before and after aseptic preparation of clipped and nonclipped arthrocentesis sites in horses. STUDY DESIGN: The hair over one midcarpal joint and one distal interphalangeal joint on each horse was clipped. The contralateral joint served as the nonclipped comparison. ANIMALS OR SAMPLE POPULATION: Twelve adult horses. METHODS: A prescrub sample for microbial culture was taken from the dorsal surface of all four joints for each horse. Each site was aseptically prepared with povidone iodine and 70% alcohol, followed by postscrub sampling for microbial culture. Colony forming units (CFUs) were determined for each sample, 24 hours after inoculation of blood agar plates. RESULTS: There was no significant difference (P > .05) in number of postscrub CFUs between clipped and nonclipped skin over the midcarpal or distal interphalangeal joints. Percent bacterial reduction (mean +/- SD%) after aseptic preparation differed significantly (P = .02) between clipped (99.8 +/- .003%) and nonclipped (96.2 +/- .05%) skin at the midcarpal joint, but not at the distal interphalangeal joint (clipped, 98.5 +/- .03% and nonclipped, 97.8 +/- 0.21%). There was a significant difference (P = .009) in number of prescrub CFUs obtained from clipped and nonclipped skin for the midcarpal joint. There was no significant difference in number of prescrub CFUs between clipped and nonclipped skin at the distal interphalangeal joint. Bacteria isolated from both clipped and nonclipped skin sampled postscrub included Bacillus sp, nonhemolytic Staphylococcus sp, and Micrococcus sp. CONCLUSIONS: The presence of hair over the midcarpal and distal interphalangeal joints does not appear to inhibit the ability of antiseptics to effectively reduce bacterial flora to an acceptable level for arthrocentesis. CLINICAL RELEVANCE: Aseptic preparation of the skin over the midcarpal and distal interphalangeal joints can be accomplished without hair removal in horses.

Animals↗