Linked Life Data

10452335

Source:http://linkedlifedata.com/resource/pubmed/id/10452335

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1999-9-16
pubmed:abstractText
Several circadian rhythms have been used to assess the phase of the endogenous circadian pacemaker (ECP). However, when more than one marker rhythm is measured, results do not always agree. Questions then inevitably arise. Are there multiple oscillators? Are some markers more reliable than others? Masking is a problem for all marker rhythms. Masking of melatonin is minimized by sampling under dim light. The dim-light melatonin onset (DLMO) is particularly convenient since it can usually be obtained before sleep. However, assessing the DLMO in low melatonin producers may be problematic, particularly with the commonly used operationally defined threshold of 10 pg/ml. This study evaluates various circadian phase markers provided by the plasma melatonin profile in 14 individuals, several of whom are low melatonin producers. The amount (amplitude) of melatonin production appears to influence the phase of many points on the melatonin profile. Accordingly, when low producers are in a data set, we now prefer a lower DLMO threshold than the one previously recommended (10 pg/ml). Indeed, there are some low producers who never exceed this threshold at any time. Radioimmunoassays are now available that have the requisite sensitivity and specificity to support the use of a lower threshold. Nevertheless, the dim-light melatonin offset (DLMOff), even when operationally defined at thresholds less than 10 pg/ml, appears to be confounded by amplitude in this study; in such cases, it may be preferable to use the melatonin synthesis offset (SynOff) because it is not confounded by amplitude and because, theoretically, it is temporally closer to the endogenous mechanism signaling the offset of production. The question of whether the termination mechanism of melatonin synthesis is related to an interval timer or to a second oscillator loosely coupled to the onset oscillator is probably best answered using the SynOff rather than the DLMOff. It is hoped that these findings will make a useful contribution to the debate on the best ways to use points on the melatonin profile to assess circadian phase position in humans.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0748-7304
pubmed:author
pubmed:issnType
Print
pubmed:volume
14
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
227-36
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
The endogenous melatonin profile as a marker for circadian phase position.
pubmed:affiliation
Department of Psychiatry, School of Medicine, Oregon Health Sciences University, Portland 97201-3098, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.