Michael Ziegler

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The secretory prohormone chromogranin A (CHGA) is overexpressed in essential hypertension, a complex trait with genetic predisposition, while its catecholamine release-inhibitory fragment catestatin is diminished, and low catestatin predicts augmented adrenergic pressor responses. These findings from studies on humans suggest a mechanism whereby diminished(More)
About 20% of astronauts suffer postspaceflight presyncope. We studied pre- to postflight (5- to 16-day missions) cardiovascular responses to standing in 35 astronauts to determine differences between 1) men and women and 2) presyncopal and nonpresyncopal groups. The groups were presyncopal women, presyncopal men, and nonpresyncopal men based on their(More)
Although all astronauts experience symptoms of orthostatic intolerance after short-duration spaceflight, only approximately 20% actually experience presyncope during upright posture on landing day. The presyncopal group is characterized by low vascular resistance before and after flight and low norepinephrine release during orthostatic stress on landing(More)
RATIONALE Dopamine beta-hydroxylase (DBH) plays an essential role in catecholamine synthesis by converting dopamine into norepinephrine. Here we systematically investigated DBH polymorphisms associated with enzymatic activity as well as autonomic and blood pressure (BP)/disease phenotypes in vivo. METHODS AND RESULTS Seventy genetic variants were(More)
BACKGROUND Chromogranin A, coreleased with catecholamines by exocytosis, is cleaved to the catecholamine release-inhibitory fragment catestatin. We identified a natural nonsynonymous variant of catestatin, Gly364Ser, that alters human autonomic function and blood pressure. METHODS AND RESULTS Gly364Ser heterozygotes and controls underwent physiological(More)
The "dark matter of life" describes microbes and even entire divisions of bacterial phyla that have evaded cultivation and have yet to be sequenced. We present a genome from the globally distributed but elusive candidate phylum TM6 and uncover its metabolic potential. TM6 was detected in a biofilm from a sink drain within a hospital restroom by analyzing(More)
Noradrenergic terminals were identified in the spinal cord of rats by immunocytochemical staining for dopamine-beta-hydroxylase. Although immunoreactive fibers and terminals were observed throughout the spinal grey matter, heavier accumulations of terminal labeling were observed in the marginal layer of the dorsal horn, in the ventral horn among(More)
STUDY OBJECTIVE Obstructive sleep apnea (OSA) patients have a high frequency of arousals. We hypothesized that arousals significantly influence tonic sympathetic nervous system function. DESIGN We examined the association of 11 variables measuring sympathetic activity, including plasma norepinephrine (NE), urinary NE, and BP measurements, with movement(More)
The objective of this study was to evaluate the effects of nocturnal sleep, partial night sleep deprivation, and sleep stages on catecholamine and interleukin-2 (IL-2) levels in humans. Circulating levels of catecholamines and IL-2 were sampled every 30 min during 2 nights: undisturbed, baseline sleep and partial sleep deprivation-late night (PSD-L; awake(More)
BACKGROUND Hypertension is a complex trait with an ill-defined genetic predisposition, in which adrenergic mechanisms seem to be involved even at the early stages. Chromogranin A is a pro-hormone stored and released with catecholamines by exocytosis; its fragment catestatin, formed in vivo, inhibits further catecholamine release as an antagonist at the(More)