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PubMed1987

[Changes in the chemical properties of environmental air in contact with polymeric construction materials used in modern buildings].

Sanitary and chemical studies of 15 types of polymeric building materials, used in the construction of modern establishments as floor coverings, lining and roofing materials, isolating materials and pastes. Elimination of chemical substances of the polymeric building materials is established. In the first days after their production or use the concentrations of the eliminated substances are considerably above the MAC--with some of the tens and hundreds times above the hygienic norm. MAC of the eliminated polymeric building materials is reached for different periods of time, as the latter define also the quarantine dates for permitting the usage of the materials. For materials which point out to considerable deviations of the norms on the first days after production or use a new instruction for technical safety is required. The diffused floor coverings on epoxide basis, paste "Pirolik" and some types of ligneous surfaces on the basis of carbamide-formaldehyde pitch, received unfavourable hygienic assessment. They show elimination of chemical substances considerably above MAC, even after more than 9 months of their production.

Air Pollutants↗
PubMedDate not supplied

[Artificial climate].

The microclimatic conditions characterizing the domestic environment, are reviewed by the author, based on personal 40-year experience, including an evaluation of its various important formative components. The author examines the general state of unawareness regarding the necessary features of the domestic microenvironment required to ensure its inhabitants thermal comfort. In conclusion a proposal is made to the authorities, requesting that they direct greater attention to this problem.

Climate↗
PubMed1986

Assay of melatonin and its metabolites: results in normal and unusual environments.

The pineal gland, via its hormone melatonin, is of major importance in the transduction of photoperiodic information in animals. It is concerned both with the synchronisation of annual cycles in photoperiodic mammals and with regulation of circadian rhythmicity in lower vertebrates. Its role, if any, in mammalian circadian systems is still speculative. By analogy with animal work the function of the human pineal is most likely to be concerned with seasonal and circadian rhythms. The study of human pineal function depends heavily on the measurement of melatonin in plasma or urine. Radioimmunoassay (RIA) and gaschromatography-mass-spectrometry (GCMS) have been successfully employed to establish the basic 24-hour rhythm. GCMS has also served to validate RIA. Following early work the reported human plasma levels of melatonin have stabilized approximately at less than 20 pg/ml in daytime with mean night time levels around 40-80 pg/ml. The high sensitivity of GCMS measures daytime levels of 2-5 pg/ml. With confidence established in melatonin assays, its physiological and pathological variations can be investigated in full. Development of assays for urinary melatonin metabolites has made possible the longterm study of circadian variations in different environments. The rhythm of melatonin production can be dissociated from the sleep wake cycle in environmental isolation and behaves like a "strong" oscillator variable. In the unusual social and photoperiodic conditions of Antarctica it remains strongly entrained to the 24 hour day. Whilst measurement of melatonin can provide circumstantial evidence of its function, abolition of its production and its administration in humans can uncover causal relationships. The effects of abolition of the melatonin rhythm by beta-adrenergic antagonists or pinealectomy has not yet been extensively studied in man. Melatonin administration, always (to date), in pharmacological amounts has hypnotic effects in man and may, in some individuals modify the rhythmic characteristics of its own secretion. It remains to be seen whether, in physiological amounts, it is causally related to aspects of human sleep and other circadian or seasonal rhythms.

Animals↗
PubMed1986

Characteristics of circadian rhythms in human functions.

Circadian rhythms are of endogenous origin, in humans as in all organisms. Under temporal isolation, i.e., after exclusion of all environmental time cues, circadian rhythmicity persists but with a period slightly deviating from 24 hours; in human, freerunning circadian rhythms always show periods close to 25 hours. In a minority of experiments, overt rhythms of different variables do not run in mutual synchrony but internally desynchronized in the steady state. This means that, indeed, most physiological rhythms, and particularly that of body temperature, hold a period close to 25 hours; it is mainly the sleep-wake rhythm (but also the overt rhythms of several more variables) which shows freerunning periods being considerably longer or shorter than 25 hours. This state of the rhythm is not concerned by the presence or absence of naps; rather, this state is characterized by a considerable stretching or compressing of the entire sleep-wake cycle. The period and other parameters of freerunning rhythms can be modified by continuously operating stimuli. Also the tendency toward the spontaneous occurrence of internal desynchronization does not depend only on personality data (e.g., neuroticism, or age) but also on the external conditions. Whereas constant light in the normal range of artificial illumination (intensities between 0 and 1500 lux) does not affect freerunning human circadian rhythms, the period is longer and the tendency toward internal desynchronization is higher under constant bright light (intensity greater than 3000 lux) than under constant light of normal intensity (or total darkness). This result has been confirmed with various physiological functions, e.g. the rhythms of deep body temperature and melatonin excretion. Social contacts (when subjects do not live singly isolated but in groups) or behavioral stress operates in the same direction as bright light. On the other hand, physical workload does not affect freerunning rhythms. Under natural conditions, the endogenously generated rhythms are synchronized to the 24-hour day. Under laboratory conditions (i.e., under temporal isolation), also artificial zeitgebers can be effective but only within limited ranges of periods; the width of such a range of entrainment is an indicator of the strength of the zeitgeber under consideration.(ABSTRACT TRUNCATED AT 400 WORDS)

Body Temperature↗