PubMed · 8769903
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R Sahelian. 1996. Melatonin.. https://doi.org/10.1001/archfami.5.4.196b
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Much evidence supports the hypothesis that mild or moderate hyperhomocysteinaemia represents an important and independent risk factor for occlusive vascular diseases. Therefore, the accurate and reliable determination of total plasma homocysteine has gained major importance for risk assessment. Furthermore, it can help in the detection of folate and vitamin B12 deficiency. This has prompted us to develop a sensitive gas chromatography-mass spectrometry (GC-MS) method in order to quantify total homocysteine in human plasma. Prior to chromatography, reduced homocysteine was released from disulfide bonds by incubation with excess dithiothreitol and converted into its N(O,S)-propoxycarbonyl propyl ester by derivatization with n-propyl chloroformate. Aminoethylcysteine served as internal standard. The method proved to be highly linear over the entire concentration range examined (corresponding to 0-266 microM homocysteine) and showed intra-assay and inter-assay variation (relative standard deviations) of approximately 5 and 5-10%, respectively. External quality control by comparison with duplicate analysis performed on a HPLC-based system revealed satisfactory correlation. The newly developed GC-MS based method provides simple, reliable and fast quantification of total homocysteine and requires only inexpensive chemicals, which are easy to obtain.
Jet lag, complaints associated with night work, and certain sleep disorders may be caused by misalignment between the endogenous circadian rhythm and the sleep/wake cycle. The authors discuss how light influences and regulates the circadian rhythm. The endogenous circadian rhythm is generated by the suprachiasmatic nucleus, and the effect of light is mediated to this nucleus directly via the retinohypothalamic tract. The effect is dependent on the timing of the light exposure relative to the nadir of the endogenous rhythm, which usually is located at about 5:00 AM. Exposure to bright light before nadir induces a phase delay, whereas a phase advance is obtained with exposure to light after nadir. The paper describes how bright light treatment can be used to reduce the effects of jet lag and of night work, sleep phase disturbances and early morning awakenings. Melatonin administration is an alternative treatment for the same type of disorders, and is also discussed in the article.
We have studied the incidence of possible triggers of the myocardial infarction regarding its site in 750 patients with anterior and 731 patients with inferior infarction. Infarctions occurred most frequently without recalling any triggering activity, especially in patients with anterior infarction (67 vs. 44%). Physical effort as the possible precipitator was also more frequent in anterior infarctions (22 vs. 16%). However, the onset of inferior infarction was more frequent during meteorological stress (9 vs. 2%), emotional stress (10 vs. 3%), after overeating (13 vs. 3%) and nicotine abuse (6 vs. 1.5%). These triggers were independent and highly significant (P < 0.02 in each case) discriminators of the site of myocardial infarction. Bimodal circadian rhythm, with primary peak between 6 and 9 h a.m. and the secondary peak between 3 and 6 p.m. was observed in patients which did not recall any triggering activity, and this was more pronounced in patients with inferior infarction. These results support the hypothesis that the influence of the vegetative tone is most pronounced in the onset of myocardial infarction of inferior wall.