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Biomedical subjects

A Zlatkis

Publications and source records attributed to A Zlatkis.

36 records · Page 2Linked to original sources
PubMed1975

Methionine dipeptide stationary phases for the resolution of enantiomers.

N-Trifluoroacetyl-L-methionyl-L-methionine cyclohexyl ester as well as the disulfide and disulfone derivatives of this phase have been synthesized. The methionine phase exhibits improved properties as a stationary phase for the separation of amino acid enantiomers as compared to other dipeptide stationary phases and can be used at temperatures ranging from 70 to 150 degrees. The sulfoxide phase, however, was incapable of resolving the enantiomeric derivatives. Physical properties of the sulfone compound limit its use as an effective resolving agent.

Amino Acids↗
PubMed1975

A micro method for the determination of volatile metabolites in biological samples. A preliminary report.

A new method for analyzing volatile metabolites in biological fluids and tissues has been developed. The procedure involves extraction of the sample with diethyl ether, concentration on a short column of glass wool by elution of the diethyl ether, then thermal desorption of the trace constituents into a chromatographic system. Small samples of 100 mul are quite adequate. The method is applicable to serum, plasma, urine and other fluids. Small tissue samples can also be used with this technique.

Animals↗
PubMed1975

Gas-chromatographic and mass-spectrometric detection of low-molecular-weight aliphatic alcohols in urine of normal individuals and patients with diabetes mellitus.

We studied the aliphatic alcohols in 100 urines from 25 patients with diabetes mellitus under treatment with insulin, oral antidiabetic medication, or special diet. The procedure involves adsorption of the low-molecular-weight urinary metabolites on a porous polymer of 2,6-diphenyl-p-phenylene oxide (Tenax GC), gas-chromatographic separation, mass spectrometric identification, and mass fragmentographic representation of the primary alcohols by a computer. The concentrations of ethanol, n-propanol, isobutanol, n-butanol, and isopentanol are increased as compared with urine from normal persons.

Aged↗
PubMed1975

Volatile organic components in the Skylab 4 spacecraft atmosphere.

The volatile organic components in the spacecraft cabin atmosphere of Skylab 4 were trapped on a solid adsorbent at various times during the mission. In post-flight analyses, more than 300 compounds in concentrations from less than 1 ppb up to 8000 ppb could be detected by high-resolution gas chromatography. In the samples of the 11th, 47th, and 77th day of the mission, approximately 100 components in the molecular weight range of 58 to 592 were identified by mass spectrometry. Besides components known from other environments, such as alkanes, alkenes, and alkylated aromatic hydrocarbons, components typical for the human metabolism such as ketones and alcohols were found. Other typical components in the spacecraft atmosphere are fluorocarbons (freons) and various silicone compounds, mostly normal and cyclic methylsiloxanes.

Air Pollutants↗
PubMed1966

Paraffinic hydrocarbons in the Orgueil, Murray, Mokoia and other meteorites.

Small samples of the Orgueil (Wiik Type I), Murray (Wiik Type II), Mokoia (Wiik Type III) and other meteorites (Alais, Ivuna, Al Rais, Bells, Cold Bokkeveld, Mighei, Nogoya, Santa Cruz, Grosnaja, Kaba, Lance, Ornans, Chainpur, Karoonda, Warrenton, and St. Caprais) were extracted with organic solvents, fractionated by silica gel chromatography, and analyzed by gas chromatography and by a new gas chromatographic-mass spectrometric technique. Only the high molecular weight hydrocarbons eluted by n-heptane were analyzed. The following observations were made: All meteorites contain paraffinic hydrocarbons in varying amounts and with a certain distribution. Normal and isomeric alkanes from Cl5 to about C25 with a maximum at C19-C21 were found in the Orgueil, Murray and Mokoia meteorites. Pristane and phytane, two saturated polyisoprenoid hydrocarbons, known to be degradation products of chlorophyll, were found in all meteorites except the Ornans, although in several (Type I and Type III, except Mokoia) the amounts were very small. No predominance of odd over even carbon-number hydrocarbons was observed except in the C22-C27 normal alkane range of some samples of the Orgueil. The concentration of alkanes in certain samples of the Orgueil was found to be about one order of magnitude lower than in others indicating a significant heterogeneity in the distribution of hydrocarbons. Practically all the meteorites of Type II and some of Type III (Mokoia) gave an essentially identical or very similar hydrocarbon chromatographic pattern, indicating a common origin for the hydrocarbons. The distribution of paraffinic hydrocarbons, including pristane and phytane, in some of these meteorites was found similar to that of microfossil-bearing pre-Cambrian rocks 2 x 10(9) years old or older. The Orguiel was similar to the Gunflint chert and Type II meteorites were similar to the Soudan rock. It remains to be seen whether these hydrocarbons were formed on the earth-moon system as suggested by Urey, on the asteroids, in the solar nebula, or whether they may be the result of a unique terrestrial contamination process.

Alkanes↗