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At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

Systematic analysis of solvents and other volatile substances by gas chromatography.

Four column packings for screening volatiles in biological material by gas chromatography are evaluated. Retention data are standardized by the calculation of retention indices, and packing materials are compared by discriminating power and identification power. A combination of 5% Carbowax 20M on Carbopack B and 0.3% Carbowax 20M on Carbopack C appears to be best suited for screening. Hydroxy-n-alkanes are used as reference substances for the calculation of retention indices.

Chromatography, Gas↗
PubMedDate not supplied

Systematic analysis of stimulants and narcotic analgesics by gas chromatography with nitrogen specific detection and mass spectrometry.

The recovery data of 40 doping agents from human urine were evaluated. Retention data were standardized by the calculation of relative retention times using N,N-diisopropyl-n-dodecane as the internal standard. The relative standard deviations of retention times were less than 0.5% for the within batch analyses and less than 0.8% for the day-to-day analyses. Good recoveries (greater than 70%) were observed for most of the drugs.

Analgesics, Opioid↗
PubMedDate not supplied

Systematic analysis of diuretic doping agents by HPLC screening and GC/MS confirmation.

The simultaneous analysis of diuretic agents by reversed-phase liquid chromatography with a diode-array detector (DAD) was performed by using a gradient elution with acetonitrile and phosphate buffer on a Hypersil-ODS column. For the spiked urine the extraction recovery of solid-phase extraction (SPE) using Sep-Pak C18 cartridge was compared with that of liquid-liquid extraction (LLE) with diethyl ether at various pH. The standard calibration curves were linear from 0.20-20.0 micrograms/mL for all diuretic agents except amiloride, 1.0-20.0 micrograms/mL, and the detection limit was about 0.2 micrograms/mL for 3 mL of urine, except that of amiloride, which was 1.0 micrograms/mL. The confirmation analysis was performed by gas chromatography/mass spectrometry (GC/MS) following methylation. The characteristic mass fragment ions obtained by electron-impact (EI) ionization (70 eV) provided identification of each diuretic agent.

Adult↗
PubMed1991

Construction of an ordered clone bank and systematic analysis of the whole transcripts of chromosome VI of Saccharomyces cerevisiae.

By comparing sequences of restriction enzyme cleavage sites and their distance data, we sorted 384 lambda phage clones containing segments of chromosome VI of S. cerevisiae and constructed an ordered clone bank for this chromosome. The physical length of this bank is 269.7 kb. The bank contains the entire chromosome including the left telomere, but it is not certain whether it contains the right telomere as well. To estimate the number of genes present on this chromosome, we performed a series of Northern hybridization experiments using 157 restriction enzyme fragments prepared from the bank as hybridization probes and total poly(A)+ RNA from vegetatively growing cells. Thus, 97 distinct transcripts were identified. The relative abundance levels of individual transcripts were measured by comparing their band intensity with that of the RPO41 transcript. It was found that the transcripts from the genes located in the telomeric and centromeric regions are less abundant as compared to those from the genes in the central regions of both arms.

Blotting, Northern↗
PubMed1997

A systematic analysis of how medical school characteristics relate to graduates' choices of primary care specialties.

PURPOSE: To examine medical school characteristics, in particular federal funding for biomedical research, as they relate to the graduates' choices of family medicine, general internal medicine, general pediatrics, or all three specialties. METHOD: Data were collected for 121 U.S. medical schools, including information on funding, faculty, curricula, and other school characteristics. In addition, a questionnaire was mailed to the schools requesting information about non-federal funding for primary care, primary care department characteristics, and primary care representation on the admission, curriculum, and promotion and tenure committees. Analyses were carried out separately for each specialty and for all three combined. The first multiple regression analysis was done to predict specialty choice (proximate predictors), the second to predict the predictors of specialty choice (intermediate predictors), and the third to predict those predictors (distal predictors). RESULTS: Prediction was best for family medicine practice. Interest at matriculation and required third-year and fourth-year time in primary care were the two best proximate predictors. The best predictors of initial interest were the percentage of rural students and special programs for primary care, while the best predictors of required time in primary care were funding for family medicine and the percentage of faculty in family medicine (intermediate predictors). The best predictor of the percentage of faculty in family medicine was funding for family medicine (distal predictor). CONCLUSION: The results suggest that the most effective way to increase the number of physicians with generalist practices is to increase the number of students interested in a family medicine career at matriculation.

Career Choice↗
PubMed1992

Evidence that the systematic analysis of bile cytology permits monitoring of hepatic allograft rejection.

Cytologic analysis was performed on 128 bile specimens collected by schedule from 12 liver transplant recipients over a 4-month period. Clinical diagnoses at the time of specimen collection were determined retrospectively, as follows: clinically stable, 75; acute rejection, 15; CMV hepatitis, 1; systemic infection, 8; ischemic injury, 24 (all within the first 4 days postop); nonclassifiable, 5. Bile analysis was done by a blinded investigator. Specimens contained ductal epithelial cells (EC) and inflammatory cells (IC), which were counted using Cytospin slide preparations. Greater than 10 cells/slide were seen in 93.3% of rejections, 91.7% of ischemic injuries, 100% of systemic infections, and 14.6% of stable patients. In samples collected after POD 4, IC were seen in 86.7% of rejections, yielding a specificity of 94.4% (P less than 0.001). If lymphoblastic cells were also seen, the specificity increased to 96.6%. Five specimens were obtained the day before the clinical diagnosis of rejection; all demonstrated IC. Seven specimens were obtained 3 days after beginning therapy for rejection. In 5 the bile contained no IC, and clinical improvement occurred; in the 2 in whom IC were found, further therapy was subsequently required. IC were seen in 5 of 8 specimens taken when systemic infection was present; the clinical setting allowed differentiation from rejection. Only 1 case of CMV hepatitis was included, thus no conclusions can be drawn for this entity. Cytoplasmic vacuolization of EC was observed in 30% of cases, in these, cyclosporine levels were significantly higher (989.9 +/- 356.9 vs. 672.8 +/- 421.2, P = 0.02). In summary, bile cytology analysis aides in the monitoring of the onset and duration of rejection. It may be an indicator of persistent rejection, and it may help prevent overimmunosuppression in those cases with normal cytological findings.

Antibodies, Monoclonal↗
PubMed2000

Systematic analysis of xanthomonads (Xanthomonas spp.) associated with pepper and tomato lesions.

The taxonomy and evolutionary relationships among members of the genus Xanthomonas associated with tomato and pepper have been a matter of considerable controversy since their original description in 1921. These bacteria, which are a major affliction of tomato and pepper crops in warm and humid regions, were originally described as a single species, but subsequent research has shown the existence of at least two genetic groups differentiated by physiological, biochemical and pathological characteristics. This work synthesizes the findings from several approaches, including pathogenicity tests, enzymic activity, restriction fragment analysis of the entire genome, DNA-DNA hybridization and RNA sequence comparisons based on a 2097 base sequence comprising the 16S rRNA gene, the intergenic spacer located between the 16S and 23S rRNA genes and a small region of the 23S rRNA gene. Within the group of xanthomonads pathogenic on pepper and tomato four distinct phenotypic groups exist, of which three form distinct genomic species. These include Xanthomonas axonopodis pv. vesicatoria (A and C group), Xanthomonas vesicatoria (B group) and Xanthomonas gardneri (D group). On the basis of phenotypic and genotypic differences between A- and C-group strains, the C strains should be considered as a subspecies within Xanthomonas axonopodis pv. vesicatoria.

Antibodies, Monoclonal↗
PubMed1987

Systematic analysis of the long-chain components of Eubacterium lentum.

The cellular long-chain component patterns of 33 strains of Eubacterium lentum were determined by gas chromatography. Two main types of long-chain component patterns were distinguished. The first (26 strains) was characterized by saturated branched-chain fatty acids (br14:0, br15:0, br16:0 and br17:0). The second (7 strains) did not contain branched-chain fatty acids and was characterized by saturated straight-chain fatty acids (11:0, 12:0, 14:0 and 16:0). Both types contained fatty aldehydes and their respective dimethyl acetals (14ald and 14dma, 16ald and 16dma). br16dma was only found in the first type. The G + C content of the DNA (Tm) of the 33 strains varied between 63.7 and 69.1 mol %. Canonical correlation analysis distinguished three subtypes within the first main type.

Base Composition↗