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Biomedical subjects

R A Hartwick

Publications and source records attributed to R A Hartwick.

26 records · Page 2Linked to original sources
PubMed1979

Reversed-phase liquid chromatographic separation of 3',5'-cyclic ribonucleotides.

A rapid, reversed-phase "high-performance" liquid-chromatographic separation of the five naturally occurring cyclic ribonucleotides is described. The separation, optimized for the measurement of these compounds in biological samples, is short (25 min), sensitive (50-100 pmol), and requires no sample pre-concentration steps. We also report an alternative isocratic elution mode, optimized for a rapid and selective analysis for adenosine 3',5'-cyclic phosphate. The identity of chromatographic peaks in biological extracts is confirmed by several methods: retention times, co-chromatography with the reference compounds, absorbance ratios, enzymatic peak-shift with cyclic nucleotide phosphodiesterase, and stopped-flow ultraviolet-scanning techniques.

Animals↗
PubMed1978

Use of UV scanning techniques in the identification of serum constituents separated by high-performance liquid chromatography.

Serum constituents separated by the reversed-phase partition mode of high-performance liquid chromatography were identified by using a stopped-flow UV scanning technique. This method of peak identification eliminates post-chromatographic sample handling. Results from UV scanning were correlated with those obtained from absorbance ratios of reference compounds and the enzymatic peak-shift technique.

Chromatography, High Pressure Liquid↗
PubMed1977

Selective analysis for adenosine using reversed-phase high-pressure liquid chromatography.

A high-pressure liquid chromatographic procedure for the selective determination of adenosine in the presence of other nucleic acid components is reported. Reversed-phase microparticle columns and an isocratic elution mode of dilute potassium dihydrophosphate and anhydrous methanol were used. The analysis is specific for adenosine and is achieved in less than 10 min. An example of the use of this analysis in a biomedical study is reported.

Adenosine↗
PubMed1976

Evaluation of microparticle chemically bonded reversed-phase packings in the high-pressure liquid chromatographic analysis of nucleosides and their bases.

The reversed-phase partition mode of high-pressure liquid chromatography was used for the analysis of seven of the naturally occurring nucleosides and their bases. With microparticle chemically bonded packings, nucleosides and their bases can be quantitatively determined in the presence of nucleotides in 30 min with high sensitivity, accuracy, and reproducibility. Peaks in chromatograms of cell extracts were identified by absorbance ratios and enzymatic peak shift methods. Applications of this technique to biochemical studies are reported.

Adenosine↗
PubMed1975

The performance of microparticle chemically-bonded anion-exchange resins in the analysis of nucleotides.

The performance of microparticles in the ion-exchange chromatographic separation of nucleotides was investigated. A microparticle chemically-bonded strong anion-exchange column packing was used for the analysis of the 5'-mono-, di- and -triphosphate nucleotides of adenine, guanine, hypoxanthine, xanthine, cytosine, uracil and thymine. It was found that excellent resolution of the majority of the nucleotides was obtained at ambient temperatures. The packings were stable and the sample capacity was greater than with pellicular resins. The retention times, peak shapes, heights and areas were highly reproducible and there was good linearity of response. Use of this column packing in biochemical studies is reported.

Adenine Nucleotides↗
PubMedDate not supplied

Quantitative relationships between the structure of beta-adrenolytic and antihistamine drugs and their retention on an alpha 1-acid glycoprotein HPLC column.

Chromatographic retention parameters of a series of 7 beta-adrenolytics and of 12 antihistamine drugs were determined employing an alpha 1-acid glycoprotein (AGP) high-performance liquid chromatographic (HPLC) column. For the group of antihistamines capillary electrophoretic (CE) retention was additionally measured in the presence of either AGP or human serum albumin (HSA). Two series of solutes hydrophobicity parameters were obtained by reversed-phase HPLC on an immobilized artificial membrane (IAM) column. The solutes studied were subjected to molecular modelling and the structural descriptors obtained were applied in studies of quantitative structure-retention (protein binding) relationships (QSRR). It was found that retention on AGP correlates well with the literature on physiological protein binding data. This retention was demonstrated to depend on hydrophobicity: to a lesser extent in the case of beta-adrenolytics and strongly in the case of antihistamines. Hydrophobicity, along with molecular width and electron excess charge on aliphatic nitrogen was demonstrated to describe retention of antihistamines on AGP. The AGP column is recommended as a convenient reactor for studies of drug-protein interactions. Preliminary CE data do not correlate with the HPLC data.

Adrenergic beta-Antagonists↗