The role of mathematical modeling in VOC analysis using isoprene as a prototypic example

Isoprene is one of the most abundant endogenous volatile organic compounds (VOCs) contained in human breath and is considered to be a potentially useful biomarker for diagnostic and monitoring purposes. However, neither the exact biochemical origin of isoprene nor its physiological role are understood in sufficient depth, thus hindering the validation of breath isoprene tests in clinical routine. Exhaled isoprene concentrations are reported to change under different clinical and physiological conditions, especially in response to enhanced cardiovascular and respiratory activity. Investigating isoprene exhalation kinetics under dynamical exercise helps to gather the relevant experimental information for understanding the gas exchange phenomena associated with this important VOC. A first model for isoprene in exhaled breath has been developed by our research group. In the present paper, we aim at giving a concise overview of this model and describe its role in providing supportive evidence for a peripheral (extrahepatic) source of isoprene. In this sense, the results presented here may enable a new perspective on the biochemical processes governing isoprene formation in the human body.Comment: 17 page

Cloning of a novel glutamate receptor subunit, GluR5 : expression in the nervous system during development

We have isolated cDNAs encoding a glutamate receptor subunit, designated GluR5, displaying 40%-41% amino acid identity with the kainate/AMPA receptor subunits GluR1, GluR2, GluR3, and GluR4. This level of sequence similarity is significantly below the approximately 70% intersubunit identity characteristic of kainate/AMPA receptors. The GluR5 protein forms homomeric ion channels in Xenopus oocytes that are weakly responsive to L-glutamate. The GluR5 gene is expressed in subsets of neurons throughout the developing and adult central and peripheral nervous systems. During embryogenesis, GluR5 transcripts are detected in areas of neuronal differentiation and synapse formation

Main effects of genotype on circadian behavioral characteristics in 12L:12D (a–c) and constant darkness (d–f).

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Main effects of genotype (and photoperiod) on circadian behavioral phenotypes.

<p>Activity monitored by infrared motion detector and wheel in LD and DD, as denoted. <i>Ex vivo Per1::Luc</i> expression is below. Significance is ascribed at <b><i>p</i></b><b>≤0.05</b>.</p

Averaged activity profiles across genotypes as monitored by (a) wheel and (b-d) infrared motion detector (IR) in LD.

<p>Each point represents the average across days and across animals within that particular genotype while in a 12L:12D cycle. Blue points represent <i>Pet-1</i>^+/+ mice; orange points represent <i>Pet-1</i>^+/− mice; black points represent <i>Pet-1</i>^−/− mice. Colored bar (<i>top</i>) represents 24 hour light cycle, where the grey is 12 hours of dark, and the yellow is 12 hours of light. Activity measured in revolutions/hour (a) or counts/hour (b–d). b | Overall IR activity profile of animals regardless of wheel state. These results are further broken-down into IR behavior with a free wheel (c) and with a locked wheel (d). See inset legend (a). Asterisks (*) denote significance at <i>p</i>≤0.05. Note the prominent early morning activity in <i>Pet-1</i>^−/− mice.</p