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Biomedical subjects

S R Parker

Publications and source records attributed to S R Parker.

At least 19 recordsLinked to original sources
PubMed1996

Homobotcinolide: a biologically active natural homolog of botcinolide from Botrytis cinerea.

A novel natural product exhibiting biological activity was isolated from a strain of Botrytis cinerea that had infected raspberry fruit (Rubus ideaus). Liquid fermentation and bioassay-directed fractionation of the organism yielded a compound with molecular formula C22H38O8 that is trivially named homobotcinolide. It significantly inhibited etiolated wheat coleoptile growth. Greenhouse-grown bean, corn, and tobacco plants were also affected by exogenous application of homobotcinolide, severe chlorosis and necrosis being exhibited in corn. The compound is a polyhydroxylated nonalactone esterified with 4-hydroxy-2-decenoic acid.

Biological Assay↗
PubMed1996

Total joint arthroplasty in a predominantly African-American population. Part two: Hip arthroplasty.

This second part of a two-part series examines total hip arthroplasty in an African-American population. Total hip arthroplasty has revolutionized orthopedic surgery since it began more than two decades ago. The quality and durability of results have enabled patients to pursue a more normal lifestyle, greatly relieved of their pain. Although many studies have reviewed the long-term results of total hip arthroplasty, none have addressed the results in a predominantly African-American population. This study retrospectively reviews the results of total hip arthroplasty in 62 African-American patients. Patients' attitudes toward this surgery, their co-morbid conditions, complications, and results were examined with regard to activity level and acceptance of the procedure.

Black or African American↗
PubMed1995

Koninginin C: a biologically active natural product from Trichoderma koningii.

Koninginin C, a congener of koninginins A and B, was isolated from Trichoderma koningii fermented on a shredded wheat medium. The compound inhibited the growth of etiolated wheat coleoptiles by 100% at 10(-3) M. It was a fine, white crystalline substance with a molecular formula of C16H28O4 and a melting point of 70-72 degrees C.

Benzoxepins↗
PubMed1990

Cyanine dye labeling reagents--carboxymethylindocyanine succinimidyl esters.

Ten carboxymethylindocyanine dyes which form the basis of a new series of fluorescent probes have been synthesized and converted into succinimidyl active esters for fluorescent labeling of proteins or other amino-containing substances. Fluorescence emission maxima for members of the series range from 575 to 780 nm. Hydrophilic, water-soluble reagents have been obtained which yield labeled antibodies with little tendency to form precipitates. The fluorescence intensities achieved are higher than those produced by labeling with the cyanine isothiocyanates described previously (Mujumdar et al.: Cytometry 10:11-19, 1989). The utility of these reagents has been demonstrated in antibody labeling for two-color immunofluorescent imaging of internal structures in a mammalian cell and for two-color flow-cytometry experiments. The use of values of chromophore-equivalent weight (W/Ceq), calculated from quantitative absorption data on dye samples, is proposed as an aid in formulating labeling procedures.

Animals↗
PubMed1987

Making childhood asthma management education happen in the community: translating health behavioral research into local programs.

The public health benefits of research can be realized only if proven new techniques are translated into readily usable processes and materials and widely adopted by professionals and patients alike. To accomplish this, a systematic technology transfer process is needed. One recent outcome of health behavior research has been identification of the skills needed by children and parents to effectively manage childhood asthma. Methods for teaching these skills were tested on hundreds of families in a variety of health care settings. They were then packaged in program manuals that guide health professionals through the teaching process and provide all necessary materials for conducting sessions. The resulting four programs teach attack prevention and control skills. They also emphasize coping skills and help families come to terms with the behavioral factors that impinge on asthma management and affect compliance with medical advice. A technology transfer project for getting initial community adoption of these programs is described. The evolution of the project, including the development of the programs themselves, packaging considerations, establishment of a unique partnership for dissemination, development of a model workshop for stimulating health professionals, implementation of programs, and follow up and evaluation, is described. Successful elements are identified at each step.

Asthma↗
PubMed1984

An experimental basis for revising the graphic rating scale for pain.

Seven subjects judged the differences between electrocutaneous shocks and words from two category rating lists describing those sensations in each of two differences estimation experiments. The electrocutaneous shocks used for the two experiments were 10 suprathreshold shock intensities determined separately for each subject. There were two distinct 7-word category rating lists. Both lists shared 6 common words; however, the seventh word made the rational ordering of the two lists different. Magnitude scales of meaning for the category rating words and sensory scales for the electrocutaneous shock intensities were determined for each of the two experiments for each subject using conjoint measurement analysis. Comparisons of the sensory scales for electrocutaneous shock between the two difference estimation experiments for each subject showed that they judged the electrocutaneous shocks similarly with the two words lists. This allowed for comparisons between the scales of meaning for the words from the category rating lists. The two word lists were not equivalent. There was substantial agreement among the subjects on characteristic spacings of quantitative values for the category rating items. These results suggest that clinical ratings scales used for analgesimetry should not assume homogeneity of spacing of category items. A scale incorporating our subjects' common understanding is presented.

Adult↗
PubMed1983

Interactions between chemotaxis genes and flagellar genes in Escherichia coli.

Escherichia coli mutants defective in cheY and cheZ function are motile but generally nonchemotactic; cheY mutants have an extreme counterclockwise bias in flagellar rotation, whereas cheZ mutants have a clockwise rotational bias. Chemotactic pseudorevertants of cheY and cheZ mutants were isolated on semisolid agar and examined for second-site suppressors in other chemotaxis-related loci. Approximately 15% of the cheZ revertants and over 95% of the cheY revertants contained compensatory mutations in the flaA or flaB locus. When transferred to an otherwise wild-type background, most of these suppressor mutations resulted in a generally nonchemotactic phenotype: suppressors of cheY caused a clockwise rotational bias; suppressors of cheZ produced a counterclockwise rotational bias. Chemotactic double mutants containing a che and a fla mutation invariably exhibited flagellar rotation patterns in between the opposing extremes characteristic of the component mutations. This additive effect on flagellar rotation resulted in essentially wild-type swimming behavior and is probably the major basis of suppressor action. However, suppression effects were also allele specific, suggesting that the cheY and cheZ gene products interact directly with the flaA and flaB products. These interactions may be instrumental in establishing the unstimulated swimming pattern of E. coli.

Alleles↗
PubMed1980

Positive identification and quantitation of isomeric cocaines by high-performance liquid chromatography.

A high-performance liquid chromatographic procedure for separating and identifying the four isomeric cocaines has been developed. Use of this procedure with an internal standard allows for the determination of the quantity of any isomeric cocaine in an unknown sample. The pitfalls and problems encountered in the use of gas chromatography and mass spectrometry in the analysis of cocaines and ecgonine methyl esters are discussed.

Chromatography, High Pressure Liquid↗
PubMed1979

Interaction of the cheC and cheZ gene products is required for chemotactic behavior in Escherichia coli.

Previous work has shown that the cheC gene product of Escherichia coli plays a key role in regulating the direction of flagellar rotation during chemotactic responses. An attempt was made to identify other stimulus transduction elements that interact with the cheC component by examining cheC revertants for functional suppressors. Approximately two-thirds of the revertants studied appeared to be due to back mutation or to second-site mutations near or within the cheC structural gene. The remainder of the revertants carried suppressor mutations that mapped at the cheZ locus. Half of these suppressors impaired chemotaxis in a cheC+ background and were shown by complementation analysis to be defective in cheZ function. These suppressors corrected cheC defects in an allele-specific pattern, suggesting that the cheC and cheZ proteins are in direct contact and are mutually corrective due to protein-protein interaction. Observation of swimming patterns and flagellar rotation in cheC cheZ mutants demonstrated that the interaction of these two gene products influences both the spontaneous frequency of flagellar reversals and the ability of the rotational machinery to respond to chemotactic stimuli. A model of this interaction and its possible role in chemotaxis are discussed.

Alleles↗