Biomedical subjects

M E Maier

Publications and source records attributed to M E Maier.

3 recordsLinked to original sources

PubMed2001

Simultaneous analysis of the di(2-ethylhexyl)phthalate metabolites 2-ethylhexanoic acid, 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in urine by gas chromatography-mass spectrometry.

A gas chromatographic-mass spectrometric method was developed for the quantitative analysis of the three Di(2-ethylhexyl)phthalate (DEHP) metabolites, 2-ethylhexanoic acid, 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in urine. After oximation with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride and sample clean-up with Chromosorb P filled glass tubes, all three organic acids were converted to their tert.-butyldimethylsilyl derivatives. Quantitation was done with trans-cinnamic acid as internal standard and GC-MS analysis in the selected ion monitoring mode (SIM). Calibration curves for all three acids in the range from 20 to 1,000 microg/l showed correlation coefficients from 0.9972 to 0.9986. The relative standard deviation (RSD) values determined in the observed concentration range were between 1.3 and 8.9% for all three acids. Here we report for the first time the identification of 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in human urine next to the known DEHP metabolite 2-ethylhexanoic acid. In 28 urine samples from healthy persons we found all three acids with mean concentrations of 56.1 +/- 13.5 microg/l for 2-ethylhexanoic acid, 104.8 +/- 80.6 microg/l for 2-ethyl-3-hydroxyhexanoic acid and 482.2 +/- 389.5 microg/l for 2-ethyl-3-oxohexanoic acid.

Caproates↗

PubMed2000

A formal total synthesis of dysidiolide.

[structure] A formal total synthesis of the natural product dysidiolide is described. Starting from a Diels-Alder reaction between an enoate and a Rawal diene, the cyclohexenone 4 was synthesized. A subsequent stereospecific methyl cuprate addition established the desired trans configuration in the cyclohexane 3. Wacker oxidation of the pentenyl side chain to the diketone 17 followed by an intramolecular aldol condensation led to the bicyclic enone 2, a key intermediate in a recently reported synthesis of dysidiolide.

4-Butyrolactone↗

PubMed1994

Sucrose threshold variation during the menstrual cycle.

Sucrose thresholds were measured at three points during the menstrual cycle for 14 women who were not taking oral contraceptives. Thirteen men also were tested at similar intervals. Sucrose thresholds of the men remained constant throughout the experiment. During menstruation and postovulation, the thresholds of the women were similar to the thresholds of the men, whereas during preovulation the thresholds of the women are significantly lower. The stable sucrose thresholds of the men suggest that ovarian hormones may be involved in the variation in sucrose sucrose thresholds of the women. The increase in sensitivity of the women during preovulation may have been related to the high level of estrogen, whereas the decrease in sensitivity during postovulation may be due to some type of interaction between estrogen and progesterone.

Adolescent↗