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Biomedical subjects

S L Morgan

Publications and source records attributed to S L Morgan.

90 records · Page 5Linked to original sources
PubMed1984

A chemical and physical comparison of ferritin subunit species fractionated by high-performance liquid chromatography.

Selected chemical and physical properties were measured for different forms of ferritin subunits which had been separated by reverse-phase high-performance liquid chromatography. Ferritin subunits from porcine spleen behaved, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, as though they were approximately Mr 2000 larger than equine spleen ferritin, whereas no difference in size was observed by gel chromatography in 6 M guanidinium chloride. All subunit species exhibited similar isoelectric focusing properties. In contrast to previous reports, no carbohydrate could be found associated with any of the isolated subunit species. Thus, the aberrant behavior of the porcine ferritin subunits between the two empirical molecular weight estimation methods appears to be the result of factor(s) other than protein intrinsic charge or covalently attached carbohydrate.

Animals↗
PubMed1984

Capillary gas chromatography-mass spectrometry of carbohydrate components of legionellae and other bacteria.

Capillary gas chromatography using fused-silica columns followed by electron impact or chemical ionization mass spectrometry was used to profile and identify neutral and amino sugars present in several legionellae and other bacteria. A modified alditol acetate derivatization method was employed to produce volatile carbohydrate derivatives. Muramic acid, a component of bacterial peptidoglycan, was detected in all legionellae examined. Heptose, a component of bacterial lipopolysaccharide, was identified in Escherichia coli organisms and in several purified Gram-negative bacterial lipopolysaccharides but not in the legionellae examined. Two amino dideoxyhexoses were found to be present in several of the Legionellae examined. The potential of gas chromatography-mass spectrometry for the direct chemical characterization of microorganisms is discussed.

Amino Sugars↗
PubMed1984

Ceftriaxone levels in blood and tissue during cardiopulmonary bypass surgery.

One gram of ceftriaxone was given intravenously to 15 patients approximately 2 h before cardiopulmonary bypass surgery. Ceftriaxone levels in plasma (mean +/- standard deviation) were 60.4 +/- 18.8 micrograms/ml (range, 17.0 to 96.0 micrograms/ml) at the beginning of bypass, 44.2 +/- 16.6 micrograms/ml (range, 9.4 to 78.6 micrograms/ml) at the end of bypass, and 19.6 +/- 9.6 micrograms/ml (range, 4.2 to 47.1 micrograms/ml) the following morning, 18.1 to 24.7 h after infusion of ceftriaxone. Concentrations in the sternal bone were 4.7 +/- 2.1 micrograms/g (range, 1.0 to 10.1 micrograms/g; tissue-to-plasma ratios, 0.066 +/- 0.036). Concentrations in the atrial appendage were 7.7 +/- 1.8 microgram/g (range, 3.6 to 10.2 micrograms/g; tissue-to-plasma ratios, 0.143 +/- 0.062). These data suggest that a single dose of ceftriaxone might be useful for prevention of infection due to susceptible pathogens.

Aged↗
PubMed1984

Capillary gas chromatographic analysis of carbohydrates of Legionella pneumophila and other members of the family Legionellaceae.

Legionella pneumophila, the causative agent of Legionnaires disease, and related organisms have previously been characterized primarily by conventional bacteriological methods, DNA-DNA hybridization, antigenic analysis, and fatty acid analysis. By capillary gas chromatographic analysis for carbohydrates, we have shown that muramic acid and glucosamine, characteristic markers of bacterial cell walls, were present in samples of L. pneumophila and a group of legionella-like organisms. Some bacterial samples contained two unusual isomeric aminodideoxyhexoses (X1 and X2). L. pneumophila was characterized by the absence of fucose and the presence of the peak X1. Tatlockia micdadei (Legionella micdadei) was distinguishable by the presence of large amounts of rhamnose and fucose and by the absence of X1 and X2. Fluoribacter strains were much more variable in their carbohydrate composition. These data suggest that, in addition to other reported techniques, carbohydrate profiling by capillary gas chromatography can be a valuable diagnostic method in reference microbiology laboratories for differentiating members of the family Legionellaceae.

Carbohydrates↗
PubMed1983

Capillary gas chromatographic analysis of alditol acetates of neutral and amino sugars in bacterial cell walls.

Several improvements in the preparation of alditol acetates of neutral and amino sugars and in the preparation of glass capillary columns for their separation are described. Modifications in sample preparation permitted the simultaneous processing of multiple samples and eliminated extraneous background peaks. Efficient and inert columns were tailor-made for the separation of alditol acetates of neutral and amino sugars by leaching glass capillaries with aqueous hydrochloric acid and dynamically coating with SP-2330.

Acetates↗
PubMed1979

The use of linear models and matrix least squares in clinical chemistry.

We present a unified approach to the use of linear models and matrix least squares with the intention of providing a better understanding of the techniques themselves and of the statistics that arise from these techniques as they are used in clinical chemistry. Emphasis is placed on the importance of appropriate experimental designs and adequately precise measurement processes for efficiently obtaining the desired information.

Chemistry, Clinical↗
PubMedDate not supplied

The confirmation of volatiles by solid-phase microextraction and GC-MS in the investigation of two traffic fatalities.

A simple, sensitive, and reliable method was developed for the confirmation of nonroutine volatiles in the investigation of two traffic fatalities. Solid-phase microextraction (SPME) fibers were used to extract volatile compounds from the headspace of sample vials; components were subsequently analyzed by gas chromatography-mass spectrometry (GC-MS). In the first case, ethanol and methylene chloride were detected in a urine sample by headspace SPME and GC-MS. The second case involved the analysis of volatile petroleum products from submitted specimens by headspace SPME and GC-MS. In both cases, SPME and GC-MS analyses provided crucial evidence in the investigation of the traffic fatalities.

Accidents, Traffic↗
PubMedDate not supplied

Metabolic complications of total parenteral nutrition: effects of a nutrition support service.

BACKGROUND: The effectiveness of Nutrition Support Services in optimizing parenteral nutrition has not been evaluated since the 1980s. METHODS: We prospectively monitored medical and surgical patients on total parenteral nutrition (TPN) in a university hospital who did not receive Nutrition Support Service recommendations to compare the incidence of metabolic complications in 1979 (group 1, n = 100) with that in 1992 (group 2, n = 106). The Service provided automatic recommendations on a subsequent group of medical service patients (group 3, n = 128) and compared them with the patients in group 2 who were on the medical service (group 2B, n = 29). RESULTS: Statistically significant changes between 1979 and 1992 included a decline in the incidence of hyperglycemia from 47% to 22% and in hypokalemia from 12% to 3% of surgical patients and an increase in hypomagnesemia from 0% to 23% of surgical patients and from 2% to 14% of medical patients. The incidence of hypophosphatemia remained > 20% in both medical and surgical patients. Within 1992, the addition of automatic recommendations had little impact on metabolic abnormalities and was associated with slightly but insignificantly lower TPN costs (not counting Service personnel costs). CONCLUSIONS: Factors such as the general integration of parenteral nutrition into tertiary medical care, standard protocols and order forms, automatic Nutrition Support Service consultations in an affiliated hospital, and nutrition curricula may be responsible for the improvements seen since 1979. However, the addition of automatic Service consultation in 1992 had only a marginal effect on metabolic complications and costs of parenteral nutrition.

Blood Chemical Analysis↗
PubMedDate not supplied

Nutrition education for medical students: evaluation of the relative contribution of freshman courses in biochemistry and nutrition to performance on a standardized examination in nutrition.

An examination previously developed and used for assessment of nutrition knowledge of medical students in the Southeastern Regional Medical-Nutrition Education Network was used to compare the effectiveness of a basic medical biochemistry course and a 58-hour required nutrition course. The examination was administered to a cohort of freshman students upon entry to medical school, after biochemistry, and then after nutrition. Two other student groups took the examination at the end of the sophomore and senior years, respectively. In the freshman cohort, mean nutrition knowledge scores increased slightly after biochemistry, (52% to 56%), which contained 37 nutrition-related lectures. The mean score of the cohort was 75% after the nutrition course. The sophomores scored 75% and the seniors 73%. These findings suggest 1) basic science courses such as biochemistry cannot be relied upon to add significantly to nutrition knowledge, and 2) a required freshman course can be an effective way to introduce basic and clinical nutrition with good retention of knowledge in subsequent years.

Biochemistry↗
PubMedDate not supplied

Antifolates in rheumatoid arthritis: a hypothetical mechanism of action.

The antifolates, methotrexate, aminopterin, 10-deazaaminopterin and sulfasalazine are clinically useful in the treatment of rheumatoid arthritis. Toxicity, rather than efficacy, appears to the the major factor limiting the usefulness of the classical antifolates (i.e., methotrexate and 10-deazaaminopterin). The fact that folate supplementation of methotrexate-treated rheumatoid arthritis patients reduces toxicity without altering efficacy also suggests that inhibition of the drug's target enzyme, dihydrofolate reductase, is not complete and not essential for efficacy. Since polyglutamates of methotrexate are direct inhibitors of thymidylate synthase and folate dependent enzymes of purine biosynthesis, the efficacy of this agent may involve blockade of these pathways. We hypothesize that blockage of aminoimidazole carboxamide ribotide transformylase, the folate dependent enzyme responsible for the insertion of carbon 2 into the purine ring, produces an immunosuppression mediated by secondary inhibition of adenosine deaminase, and S-adenosyl homocystein hydrolase by aminoimidazolecarboxamide metabolites. This mechanism of immunosuppression may explain the clinical effect of methotrexate, 10-deazaaminopterin, and possibly sulfasalazine. Since purine biosynthesis is a fundamental process, blockading this pathway may also decrease leukotriene production and interleukin-1 expression, which also could contribute to the efficacy of methotrexate.

Acyltransferases↗