PubMed Health⌕ Search

Biomedical subjects

H C Thompson

Publications and source records attributed to H C Thompson.

At least 19 recordsLinked to original sources
PubMed1992

Determination of aflatoxins in food products by chromatography.

Several chromatographic methods for the determination of aflatoxins in agricultural and food products are reviewed. During the past two decades, identification and determination of aflatoxins were done by thin-layer chromatography (TLC) because it was easy, fast and inexpensive. However, high-performance liquid chromatography (HPLC) using fluorescence detection is now the method of choice for determining aflatoxins and is also growing in popularity for their identification. The reasons for selecting HPLC over TLC can be summarized as the ability to analyze for a wide variety of compounds, including compounds that are easily degraded by heat, light or air, the ease of adaptation to confirmatory procedures, the potential for automation and the dramatic improvement in instrumentation, including the development of increasingly sensitive fluorescence and electrochemical detectors and short, high-resolution, reversed-phase columns.

Aflatoxins↗
PubMed1992

Pharmacokinetics of high dose thiotepa in children undergoing autologous bone marrow transplantation.

Pharmacokinetics of high dose thiotepa was studied in 10 children who received this drug as a 2 h infusion at a dose of 300 mg/m2 daily for 3 days. The thiotepa was quantitated using a modification of a previously published gas chromatographic method. Samples were obtained at predetermined times post infusion. The peak plasma concentrations immediately following the infusion ranged from 5.5 to 25.2 (2.0 +/- 6.6) mg/l and the 8 h post infusion ranged from 0.06 to 0.7 (0.32 +/- 0.21) mg/l. The disposition of thiotepa was best described as a simple one compartment open model. The mean (+/- SEM) values for apparent elimination half-life (t1/2 beta), total plasma clearance (CL) and steady volume of distribution (VDss) were 1.3 x h, 11.25 (1.73) l/h/m2 and 19.38 (2.58) l/m2 respectively. In conclusion the pharmacokinetics of high dose thiotepa in children between 2 and 12 years of age do not appear to vary from those reported in children receiving 75 mg/m2 or adults receiving similar doses.

Bone Marrow Transplantation↗
PubMed1989

Analysis, characterization, and purification: requirements for toxicological evaluation of 1,4-dithiane.

1,4-Dithiane is an organo-sulfur chemical associated with production and storage of munitions. Toxicological evaluation of this chemical was scheduled in rats because of the paucity of such information. Prerequisite for the evaluation was the development of gas chromatographic procedures using flame ionization detection to determine the purity of the test chemical and to certify the concentration and stability of the chemical in the dosage form, sesame oil. Mass and nuclear magnetic resonance spectrometry procedures are described for assessing the structural character and purity of the test chemical. A procedure for the purification of the test chemical and data concerning its solubility in various solvents are also presented.

Chromatography, Gas↗
PubMed1987

Formation of artifactual metabolites of doxylamine following acid hydrolysis.

This study describes the use of gas chromatographic-mass spectrometric, high-performance liquid chromatographic and capillary column gas chromatographic separation techniques in demonstrating the production of several artifactual compounds reported in the literature as metabolites of doxylamine. Rhesus monkey urinary extracts which contained doxylamine and doxylamine metabolites were examined with and without acid hydrolysis. The production of 1-phenyl-1-(2-pyridinyl)ethanol and 1-phenyl-1-(2-pyridinyl)ethylene under acid hydrolysis conditions was demonstrated. These artifactual products were shown to originate from the acid hydrolysis of 2-[1-phenyl-1-(2-pyridinyl)ethoxy] acetic acid and not from doxylamine.

Animals↗
PubMed1987

Evaluation of porous polymer traps for analysis of four volatile N-nitrosamines using thermal desorption injection coupled with a gas chromatograph-thermal energy analyzer.

Three porous polymer adsorbents, Tenax-TA, Chromosorb 102, and Chromosorb 103 were investigated as potential gas phase, trapping agents for volatile N-nitrosamines using a thermal desorption injector coupled with a gas chromatograph-thermal energy analyzer. N-Nitrosodimethylamine was used as the model N-nitrosamine for determining break-through volume, the effect of temperature on retention volume, and collection efficiency at 25 degrees C for each adsorbent. Results from these three parameters indicated that Chromosorb 103 exhibited the best adsorbent characteristics for the pre-concentration of volatile N-nitrosamines. A mixture of three dialkyl N-nitrosamines (dimethyl, diethyl, and dipropyl), and N-nitrosopyrrolidine were analyzed using a high-temperature mineral oil purge and trap procedure. Recoveries ranged from 82.2 to 102.8% at levels of 10 and 100 ng of each N-nitrosamine added.

Chromatography, Gas↗
PubMed1987

Characterization, purification, and analysis of solvent yellow 33 and solvent green 3 dyes.

Thin-layer chromatography and high-performance liquid chromatography (HPLC) with linear photodiode array detection (LPDA) were used to separate impurities from two commercial dyes. Gravity flow liquid chromatography was used to purify reference standards of the dyes. Normal phase HPLC with LPDA detection was used to determine purities of submitted samples by comparing responses to those of the reference standards. Electron impact mass spectrometry and nuclear magnetic resonance were utilized to confirm structures of the dyes and their impurities.

Anthraquinones↗
PubMed1987

Can pediatrics meet the challenge of social ill health?

The American Academy of Pediatrics mission statement equates physical, mental, and social health--indeed a major challenge for the profession. This article outlines the magnitude and evolution of physical, mental, and social problems presented to pediatricians during this century. Included are manifestations, and some causes, of social ill health; the response of research and education to the problems; and future steps needed if the challenge is to be met. The unanswered and disturbing question presents itself: Can, or should, pediatrics seriously attempt to meet the challenge of social ill health?

Humans↗
PubMed1985

Analysis of D-penicillamine by gas chromatography utilizing nitrogen--phosphorus detection.

A method is presented for the analysis of the "orphan" drug D-penicillamine (D-Pa), which is used for the treatment of the inherited rare copper metabolism dysfunction known as Wilson's disease, by assaying a derivative of the compound by gas chromatography employing a rubidium sensitized nitrogen--phosphorus detector. Analytical procedures are described for the analyses of residues of D-Pa X HCl salt in animal feed and for the analyses of the salt or free base from aqueous solutions by utilizing a single-step double derivatization with diazomethane--acetone. Stability data for D-Pa X HCl in animal feed and for the free base in water are presented. An ancillary fluorescence derivatization procedure for the analysis of D-Pa in water is also reported.

Animal Feed↗
PubMed1985

Mass spectral characterization of doxylamine and its rhesus monkey urinary metabolites.

This study describes the use of mass spectrometry (MS), high-performance liquid chromatography (HPLC) and chemical derivatization techniques for the identification of doxylamine and five rhesus monkey urinary metabolites. The analyses were performed using chemical ionization mass spectrometry with either methane or ammonia as the reagent gas. The confirmation of the structures of two of these urinary metabolites was aided by the synthesis of doxylamine N-oxide and desmethyldoxylamine and by the use of methylation and acetylation derivatization techniques. Doxylamine N-oxide, desmethyldoxylamine, didesmethyldoxylamine, and two metabolites which resulted from the cleavage of the aliphatic tertiary nitrogen side chain to the subsequent 2-[1-phenyl-1-(2-pyridinyl)ethoxy]acetic acid or 2-[1-phenyl-1-(2-pyridinyl)ethoxy]methanol compounds were isolated and identified from rhesus monkey urine. Additional data concerning the mass spectral analysis of derivatization or reaction products from the three chloroformate reactions with doxylamine, and the synthesis and separation techniques which afforded mass spectral identification of the urinary metabolites are also presented.

Animals↗
PubMed1978

It doesn't work!

Explore the source record for details and available documents.

Child↗
PubMed1977

Management criteria, recording of performance, and peer review of tonsillopharyngitis.

As part of a national study to formulate criteria for chart audit of quality assurance of child health care, criteria were developed for diagnosis and management of tonsillopharyngitis. These criteria were validated by pediatricians and family physicians in academic medicine and in practice. They were judged relevant to the medical care process and patient outcome by both. The selected criteria were also recommended by the majority of two large physician groups for use in peer review. In the first three phases of the study most of these criteria were said to be performed and recorded by a majority of physicians. However, in the fourth (community) phase, when charts of 166 primary-care physicians were actually audited, documentation was so poor that peer review by chart audit would be impractical at present.

Child↗
PubMed1977

Harvester ant sensitivity: in vitro and in vivo studies using whole body extracts and venom.

Harvester ant stings by Pogonomyrmex maricopa (Pm) or Pogonomyrmex rugosus (Pr) resulted in serious reactions in 8 patients, 4 with generalized reactions and 1 with large local reactions. Exposure to one species in the genus Pogonomyrmex (P) appeared to cross-sensitize ant-sensitive patients to other species in the same genus as evidenced by skin testing and leukocyte histamine release, but these patients were less sensitive to extracts from other stinging Hymenoptera, including bee, wasp, yellow jacket, hornet, and Formica ant. Pr ant venom was obtained by electrical stimulation of live ants for leukocyte histamine release studies. The venom preparation was considerably more effective in inducing histamine release than a body extract derived from gasters, the posterior abdominal segments. Rabbits immunized with an extract from one species produced precipitating antibodies against the injected extract withich cross-reacted with extracts from other species of harvester ant, but not with other stinging Hymenoptera. Humans and rabbits appear to react to certain genus-specific antigens present in Pogonomyrmex whole body extracts. Proper identification of the offending ant is crucial for proper testing and treatment of ant-sensitive patients.

Animals↗
PubMed1976

Quality assurance of ambulatory child health care opinions of practicing physicians about proposed criteria.

This paper reports the opinions of a representative sample of 1,329 physicians providing primary care regarding criteria developed by the Joint Committee on Quality Assurance for evaluation of ambulatory child health care. Areas of care were health supervision (in four age ranges), tonsillopharyngitis, bronchial asthma, and urinary infection. The criteria had been previously appraised by 452 "experts"--academicians and practitioners. Physicians rated criteria for relevance to health outcome, and desirability for use in peer review. They also stated whether they usually performed and recorded each item and gave reasons for not recording. Agreement between the pediatricians and other physicians of the sample and the "experts" was close regarding relevance to health outcome, but many fewer criteria were recommended for peer review by the sample. A significant number of respondents said they performed but did not record many of the criteria. Documentation of only abnormal findings was the main reason given for not recording. Criteria dealing with developmental or behavioral assessment or with counseling were rated lower in all categories than more easily measured items.

Adolescent↗
PubMed1976

Office records in the evaluation of quality of care.

Trained reviewers audited 10,500 charts in the offices of 166 pediatricians and family physicians. Criteria for child health supervision and three diseases had been previously validated for relevance to health outcome and suitability for peer review. Overall documentation of criteria was approximately 50 per cent. Measurements and laboratory data were recorded frequently; counseling items infrequently. Pediatricians documented health supervision items more often than family physicians. Members of large groups recorded more than those in solo practice or small groups. The presence of equipment considered important for health care did not correlate with percentage of recording. The method of review was judged accurate and acceptable by physicians, but only 50 per cent said the results accurately portrayed their performance. Lack of accurate recording may make it impossible to achieve valid peer review of ambulatory child care.

Adolescent↗
PubMed1976

Biological properties of an immunogenic pneumococcal subcellular preparation.

A subcellular fraction, designated PSP-3R, prepared from rough, type 3R Streptococcus pneumoniae is described, which affords excellent protection to mice against challenge with smooth organisms of the homologous serotype 3S and significant protection against heterologous challenge with serotypes 1S and 2S. Adjuvant enhances the protective capacity of the vaccine but is not necessary for immunogenicity. Protection induced by PSP-3R can be passively transferred tp normal mice with serum from actively immunized animals. The protective capacity can be completely absorbed out with rough or smooth type 3 organisms but not with rough type 1R or 2R cells. PSP-3R immune serum was tested in a passive hemagglutination assay against type 3 capsular polysaccharide-coated erythrocytes and found to have no detectable anticapsular antibody. The possible identity of the immunogen (s) in the vaccine is discussed.

Animals↗