The Positive Association between Melatonin-Containing Food Consumption and Older Adult Life Satisfaction, Psychoemotional State, and Cognitive Function

The purpose of this study was to test the hypothesis that melatonin-containing food (FMT) consumption is associated with a better sleep schedule and cognitive and psychoemotional state in older adults. A cross-sectional study of 557 (79% females) older adults living in the community with a mean age of 68.9 ± 7.7, ranging from 50 to 90 years, was conducted. The study, conducted in May and September 2023 using a face-to-face interview, collected personal data and assessed FMT intake during the day (FMTday) and for dinner (FMTdinner), life satisfaction, positive and negative affect, depression severity, cognitive functions, and sleep characteristics. Multiple regression and logistic regression analysis, adjusted for co-factors, were used to assess the association between the studied indicators. Multiple regression analysis showed that older adults with higher FMT consumption are more satisfied with life (FMTdinner: β = 0.107; ∆R2 = 0.011; p = 0.020), have a lower level of depression (FMTday: β = -0.124; ∆R2 = 0.015; p = 0.003), and higher scores in positive affect (FMTday: β = 0.169; ∆R2 = 0.016; p = 0.007; FMTdinner: β = 0.136; ∆R2 = 0.019; p = 0.003). Logistic regression analysis showed that older adults with higher FMT consumption are less likely to have depression (FMTday: OR, 0.614; 95% CI, 0.436-0.864; p = 0.005; FMTdinner: OR, 0.671; 95% CI, 0.476-0.945; p = 0.023), and they perform better on logical thinking tests (FMTday: OR, 2.066; 95% CI, 1.131-2.204; p = 0.013; FMTdinner: OR, 1.887; 95% CI, 1.183-2.138; p = 0.033). A greater life satisfaction as well as a decrease in the cognitive impairment and psychoemotional state of older adults is associated with a higher consumption of melatonin-containing foods.

Association of Chrononutrition Indices with Anthropometric Parameters, Academic Performance, and Psychoemotional State of Adolescents: A Cross-Sectional Study

Adolescents are an at-risk group for circadian misalignment. The contribution of sleep-wake rhythm instability to the psychoemotional, cognitive, and weight disorders of adolescents has been studied in sufficient detail. At the same time, there is insufficient information about the association between chrononutrition indices and the well-being of adolescents. The aim of this study is to investigate the relationship between chrononutrition indices and academic achievement, psychoemotional state, and anthropometric indicators in adolescents. The study involved 12,759 students in grades 6-11 of secondary schools, aged 14.2 ± 1.7 years old; 57.2% of whom were girls. Participants provided personal data, frequency and time of meals during the day and at night, on weekdays and weekends, and completed the Zung Self-Rating Depression Scale and the Yale Food Addiction Scale. There is a U-shaped association between eating mid-phase (EPFc), eating jetlag (EJL), and eating window (EW) with GPA, ZSDSI, and FA. At the same time, the frequency of night eating (NE) is linearly associated with the studied parameters. NE is the strongest predictor of ZSDSI (β = 0.24), FA (β = 0.04), and GPA (β = -0.22). EPFc, EJL, and EW practically do not differ in the strength of their association with the studied indicators. ZSDSI is most closely associated with the chrononutrition indices. There is a weak negative association between BMI and EW (β = -0.03) and NE (β = -0.04). Thus, circadian eating disorders are more often observed in adolescents with poor academic performance, high levels of depression, and food addiction.

Afternoon school shift is associated with increased risk of overweight/obesity in 11-14-year-old females with early and intermediate chronotype

OBJECTIVE

The purpose of this study was to compare the anthropometric and sleep-wake rhythm characteristics of schoolchildren that attend school in morning and afternoon school shifts.

METHODS

We recruited 18 481 individuals (females: 56.4%) aged 11 to 18 years old with an average age of 14.4 ± 1.7 years old. In total, 812 (4.2%) questionnaires were incomplete. The self-reported height and weight were used to assess the sex- and age-corrected body mass index of the participants. The Munich ChronoType Questionnaire was used to assess the chronotype, social jetlag, and sleep duration of the participants.

RESULTS

In total, 12.6% of the participants were affected by overweight or obesity. The overweight and obesity incidence rate was higher among the students studying in the afternoon (odd ratio [95%CI]: 1.33 [1.16-1.52]). The afternoon school shift had a negative impact on the anthropometric indicators only in the 11-14-year-olds (1.29 [1.11-1.50]) and girls (1.26 [1.04-1.54]) with an early (1.27 [1.03-1.56]) and intermediate (1.30 [1.07-1.58]) chronotype.

CONCLUSION

The data obtained indicated that the afternoon school shift is not ideal, especially for female children and adolescents under 15 years old with an early and intermediate chronotype.

The Association between Melatonin-Containing Foods Consumption and Students' Sleep-Wake Rhythm, Psychoemotional, and Anthropometric Characteristics: A Semi-Quantitative Analysis and Hypothetical Application

Food is an important source of melatonin (MT), which belongs to a group known as chronobiotics, a class of substances that affect the circadian system. Currently, no studies have been conducted on how the consumption of foods containing MT (FMT) is associated with indicators characterizing the human circadian system. In this study, we tested the hypothesis that FMT consumption is associated with chronotype and social jetlag. A total of 1277 schoolchildren and university students aged M (SD) 19.9 (4.1) years (range: 16-25 years; girls: 72.8%) participated in a cross-sectional study. Each participant completed an online questionnaire with their personal data (sex, age, height, weight, waist circumference, and academic performance) and a sequence of tests to assess their sleep-wake rhythm (the Munich Chronotype Questionnaire), sleep quality (the Pittsburgh Sleep Quality Index), and depression level (the Zung Self-Rating Depression Scale). Study participants also completed a modified food frequency questionnaire that only included foods containing MT (FMT). They were asked how many foods containing MT (FMT) they had eaten for dinner, constituting their daily serving, in the past month. The consumption of foods containing MT (FMT) during the day (FMTday) and at dinner (FMTdinner) was assessed using this test. Multiple regression analyses were performed to assess the association between the studied indicators. We found that higher FMTday values were associated with early chronotype (β = -0.09) and less social jetlag (β = -0.07), better sleep quality (β = -0.06) and lower levels of depression (β = -0.11), as well as central adiposity (β = -0.08). Higher FMTdinner values were associated with a lower risk of central adiposity (β = -0.08). In conclusion, the data obtained confirm the hypothesis that the consumption of foods containing MT (FMT) is associated with chronotype and social jetlag in adolescents and young adults.

Food addiction and emotional eating are associated with intradaily rest-activity rhythm variability

PURPOSE

The aim of the present investigation was to study the associations among parameters characterizing eating behavior and actimetry-derived indices of circadian rhythm of motor activity.

METHODS

The study involved 81 healthy participants (average age: 21.5 ± 9.6 y, women: 77.8%). Each study participant provided personal data, filled out the Yale Food Addiction Scale and the Dutch Eating Behavior Questionnaire, and wore a wrist actimeter for 7 consecutive days to record motor activity. Using time series treatments, we obtained: (a) three cosinor-derived parametric indices [Medline Estimating Statistics of Rhythm (MESOR), amplitude, and acrophase], and (b) four non-parametric indices [interdaily stability, intradaily variability (I.V.), most active 10-h period (M10), and least active 5-h period] characterizing the 24-h rhythm of motor activity. A multiple regression analysis adjusted for age, sex, and BMI was performed to assess the associations among the studied indicators.

RESULTS

It was shown that I.V. is a predictor of symptoms of food addiction (β = 0.242, P = 0.037) and emotional eating (β = 0.390, P = 0.004), MESOR is a predictor of symptoms of food addiction (β = 0.342, P = 0.003), and M10 predicts restraint (β = 0.257, P = 0.015) and emotional eating (β = 0.464, P = 0.001).

CONCLUSION

It was shown for the first time that an increase in symptom counts of food addiction is associated with an increase in the average level and fragmentation of 24-h rhythm of motor activity.

LEVEL OF EVIDENCE

Level V, cross-sectional descriptive study.

Later school start time is associated with better academic performance, sleep-wake rhythm characteristics, and eating behavior

There are numerous studies which show that an early school start time has a negative impact on the sleep, well-being, and academic performance of students. There is not enough information on the association between school start time and eating disorders, however: the disruption of the circadian rhythm is known to be a risk factor for eating disorders. The aim of this study is to analyze the relationship between school start time (SST) and the sleep, well-being, academic performance, and eating behavior of children and adolescents. The study was conducted in April and May 2021 in two regions of Russia: the Komi Republic and Yekaterinburg. The online study involved the anonymous and voluntary participation of 6571 students in grades 6-11 (mean age: 14.5 ± 1.6 years, 60.1% female), who have morning classes. All participants were divided into three groups according to SST: 08:00 (n = 3661), 08:30 (n = 2020), and 09:00 (n = 890). Each participant of the study indicated their place of residence, SST, age, sex, height, weight, academic performance, and filled out the Munich Chronotype Questionnaire, the Zung Self-Rating Depression Scale, and the Yale Food Addiction Scale for Children. As a result of multiple regression analysis, it was shown that schoolchildren with SST of 09:00 wake up at a later time on school days (B = 0.432; ΔR² = 0.039), sleep more (B = 0.293; ΔR² = 0.004), have less pronounced social jetlag (B = -0.223; ΔR² = 0.005) and sleep loss (B = -0.292; ΔR² = 0.005), and higher academic performance (B = 0.113; ΔR² = 0.003) than schoolchildren with SST of 08:00. As a result of logistic regression analysis, it was found that the frequency of the detection of food addiction is ~30% lower in schoolchildren with SST of 09:00 (OR = 0.690; 95% CI = 0.485-0.981) than in their peers with SST of 08:00. Thus, an overly early SST in Russia has a negative impact on the sleep function, academic performance, and eating behavior of children and adolescents.

Impact of COVID-19 Lockdown in Eating Disorders: A Multicentre Collaborative International Study

Background. The COVID-19 lockdown has had a significant impact on mental health. Patients with eating disorders (ED) have been particularly vulnerable. Aims. (1) To explore changes in eating-related symptoms and general psychopathology during lockdown in patients with an ED from various European and Asian countries; and (2) to assess differences related to diagnostic ED subtypes, age, and geography. Methods. The sample comprised 829 participants, diagnosed with an ED according to DSM-5 criteria from specialized ED units in Europe and Asia. Participants were assessed using the COVID-19 Isolation Scale (CIES). Results. Patients with binge eating disorder (BED) experienced the highest impact on weight and ED symptoms in comparison with other ED subtypes during lockdown, whereas individuals with other specified feeding and eating disorders (OFSED) had greater deterioration in general psychological functioning than subjects with other ED subtypes. Finally, Asian and younger individuals appeared to be more resilient. Conclusions. The psychopathological changes in ED patients during the COVID-19 lockdown varied by cultural context and individual variation in age and ED diagnosis. Clinical services may need to target preventive measures and adapt therapeutic approaches for the most vulnerable patients.

COVID Isolation Eating Scale (CIES): Analysis of the impact of confinement in eating disorders and obesity-A collaborative international study

Confinement during the COVID‐19 pandemic is expected to have a serious and complex impact on the mental health of patients with an eating disorder (ED) and of patients with obesity. The present manuscript has the following aims: (1) to analyse the psychometric properties of the COVID Isolation Eating Scale (CIES), (2) to explore changes that occurred due to confinement in eating symptomatology; and (3) to explore the general acceptation of the use of telemedicine during confinement. The sample comprised 121 participants (87 ED patients and 34 patients with obesity) recruited from six different centres. Confirmatory Factor Analyses (CFA) tested the rational‐theoretical structure of the CIES. Adequate goodness‐of‐fit was obtained for the confirmatory factor analysis, and Cronbach alpha values ranged from good to excellent. Regarding the effects of confinement, positive and negative impacts of the confinement depends of the eating disorder subtype. Patients with anorexia nervosa (AN) and with obesity endorsed a positive response to treatment during confinement, no significant changes were found in bulimia nervosa (BN) patients, whereas Other Specified Feeding or Eating Disorder (OSFED) patients endorsed an increase in eating symptomatology and in psychopathology. Furthermore, AN patients expressed the greatest dissatisfaction and accommodation difficulty with remote therapy when compared with the previously provided face‐to‐face therapy. The present study provides empirical evidence on the psychometric robustness of the CIES tool and shows that a negative confinement impact was associated with ED subtype, whereas OSFED patients showed the highest impairment in eating symptomatology and in psychopathology.

Food addiction in young adult residents of Russia: Associations with emotional and anthropometric characteristics

The incidence of food addiction (FA) and associations between FA and anthropometric and psycho-emotional characteristics of young Russian adults were studied. In this study, 1,237 students (age, M = 20.6, SD = 4.6 years; 79% females) of universities located in four cities of Russia were attended. They provided demographics and filled in the Yale Food Addiction Scale (YFAS), the Dutch Eating Behavior Questionnaire, and the Zung Self-Rating Depression Scale. Data were analysed via Chi-squared tests, logistic regression analysis, and an analysis of covariance. 13.2% of participants met diagnostic criteria for FA based on the YFAS. On average, the participants reported 2.6 FA symptoms (SD = 1.5). FA was more commonly detected in females (OR = 1.86, 95% CI = 1.10, 3.15, p = .021). No relationship was found between age and the incidence of FA. Significant positive associations between FA, the severity of depression (OR = 2.31, 95% CI = 1.91, 2.80, p = .000), and an emotional eating behaviour (OR = 1.45, 95% CI = 1.20, 1.76, p = .000) were found. The waist-to-height ratio was found to be the anthropometric indicator most closely associated with FA (OR = 1.49, 95% CI = 1.27, 1.76, p = .000). HIGHLIGHTS: The prevalence of food addiction in the current sample was 13.2%. In young Russian adults, emotional eating behaviour and depression are associated with food addiction. In young Russian adults, the waist-to-height ratio is the anthropometric indicator most closely associated with food addiction.

Chronotype, social jetlag, and time perspective

The phase of entrainment (chronotype) is known to be associated with time perspective (TP), suggesting that the state of circadian system is involved in the long-term planning of human life. However, little is known regarding the influence of circadian misalignment on long-term planning ability. The aim of this study was to investigate the association between social jetlag (SJL) and TP. A total of 1064 schoolchildren and university students (mean age ± standard deviation, 19.2 ± 2.9 years; range, 15-25 years; females, 71.7%) from four cities in the Russian Federation located between 56.9 and 61.7 degrees North completed the Munich ChronoType Questionnaire, the Pittsburgh Sleep Quality Index, the Seasonal Pattern Assessment Questionnaire, and Zimbardo Time Perspective Inventory. Study participants also indicated personal data (age, sex, height weight, place of residence, and achievements). A multiple regression analysis with stepwise inclusion of predictors in the model was performed to evaluate associations between time perspective characteristics (dependent variables) and predictor variables. The change in R² was used as the measure of effect size. Chronotype was found to be a moderate predictor of future TP (B = 0.034; ΔR² = 0.037). In addition, sleep quality was found to be a moderate predictor of past negative (B = 0.043; ΔR² = 0.074), present fatalistic (B = 0.021; ΔR² = 0.035), and deviation from balanced TP (B = 0.034; ΔR² = 0.066). Mood seasonality was a moderate predictor of present hedonistic TP (B = 0.016; ΔR² = 0.038), and social jetlag was a weak predictor of present fatalistic (B = 0.052; ΔR² = 0.019), future (B = -0.033; ΔR² = 0.004), and deviation from balanced TP (B = 0.047; ΔR² = 0.012). In conclusion, this study found a weak but significant association between social jetlag and TP in adolescents and young adults.

Sleep characteristics, chronotype and winter depression in 10-20-year-olds in northern European Russia

The purpose of this work was to examine the relationships between geographical coordinates and the prevalence of winter depression (SADW ), and to compare the sleep characteristics and chronotype of youths with and without SADW . We conducted a cross-sectional study of self-reported sleep characteristics, chronotype and winter depression in northern European Russia. Two questionnaires, the Munich Chronotype Questionnaire (MCTQ) and the Seasonal Pattern Assessment Questionnaire (SPAQ), were administered to a total of 3435 adolescents aged 10-20 years (1517 males and 1918 females). The prevalence of SADW in the study population was 8.4% and sub-SADW 11.8%. Four variables predicted the likelihood of SADW in youths: sex [higher in females: odds ratio (OR): 1.87, P < 0.0001], age (increases with age: OR: 1.09, P < 0.001), latitude (higher in the North: OR: 1.49, P < 0.029) and position in the time zone (higher in the West: OR: 1.61, P < 0.001). Later sleeping and waking, longer sleep latencies, more severe sleep inertia, shorter total sleep times and lower sleep efficiencies were observed in both males and females with SADW . The influence of SADW on sleep characteristics was more pronounced on school days. Significant phase delays of the sleep-wake rhythm and severe social jetlag (the difference between the mid-point of sleep phase at weekends and on workdays) were observed in females with SADW , but not in males. There are significant differences in sleep characteristics and chronotype between people with SADW and no-SAD. We demonstrate that both latitude of residence and location within the time zone are significant predictors of SADW in young inhabitants of the North.

Impact of cabbage pectin-protein complex on microbial β-glucuronidase activity

We previously demonstrated that pectin-protein complex (PPC) isolated from white cabbage adsorbs the β-glucuronidase (βG) enzyme of E. coli. Concurrently, we discovered a significant increase in βG activity in the presence of PPC. The aim of this study is to identify the structural components of PPC that are responsible for βG adsorption and activation. PPC was isolated from white cabbage using a saline solution containing hydrochloric acid (pH 1.5) at 37 °C for 4 h. PPC proteins were precipitated by aqueous 10% (m/v) trichloroacetic acid to yield the pectin-protein fractions PPC1 and PPC2. PPC was digested using 1,4-α-d-galacturonase, yielding the PPC6 fraction. Partial acid hydrolysis of PPC revealed the galacturonan fraction, PPC3, to be the core of the macromolecule. The purified PPC4 and PPC5 fractions were isolated from PPC by ion-exchange chromatography on DEAE-cellulose. βG activity and its adsorption in the PPC fractions were studied in vitro. Crystalline cellulose was used as a control. This study found that the PPC3 fraction (the galacturonan core) does not adsorb βG and does not affect its activity. The adsorption of βG in the PPC samples is inversely proportional to the degree of methyl esterification of its carbohydrate component. The PPC4 and PPC5 fractions adsorb the highest proportion of βG (51.2% and 54%, respectively). The stimulation of βG enzyme activity is directly proportional to the protein content of the PPC sample. The PPC and PPC1 samples have the greatest ability to increase βG activity (57.6% and 52.1%, respectively).

Impact of perinatal photoperiod on the chronotype of 11- to 18-year-olds in northern European Russia

The study investigates the effect of the month of birth and ambient light conditions at birth on sleep length and chronotype among residents of high latitudes. The authors surveyed 1172 persons (609 girls, 563 boys) age 11 to 18 yrs living in five villages and four towns located between 59.5°N and 67.6°N latitude. Survey participation was voluntary and anonymous. Sleep length and chronotype were assessed using the Munich chronotype questionnaire (MCTQ). The study showed the sleep length and chronotype of the children and adolescents depended on sex, age, type of settlement (town/village), and latitude of residence. Latitude exerted a stronger impact on sleep length and chronotype of children and adolescents living in villages than on those of their urban counterparts. Month of birth had no effect on sleep length and chronotype. There was a significant effect of the time of sunrise, sunset, and day length at birth on the chronotype of children and adolescents. A later chronotype was observed in the sample of young persons living above the Arctic Circle who were born during the polar day and polar night.

The pattern of entrainment of the human sleep-wake rhythm by the natural photoperiod in the north

Recently, it was shown that the sleep-wake rhythm of the inhabitants of the temperate zone is entrained to sun time. In the North, significant seasonal changes in the photoperiod may interfere with entrainment of the circadian system to sunlight. This investigation assessed the influence of photoperiod characteristics on the sleep length and sleep-wake rhythm of residents of high latitude. The study was conducted in four towns and six villages located between 59.5?N and 67.6?N latitude between the months of October and May from 2009 through 2011 and included 2822 subjects aged 10 to 97 yrs, 1621 of whom were females and 1201 males. The chronotype and sleep length of the subjects were assessed using the Munich Chronotype Questionnaire. The instructions for the questionnaire stressed the need to specify the sleep-wake schedule during the week preceding the date of completing the questionnaire. The study found that the length of sleep and the chronotype of the inhabitants surveyed in Northern European Russia depend on age, sex, type of settlement, and place of residence. The time of sunrise was a stronger predictor of sleep length and chronotype than the time of sunset and day length. A later chronotype and shorter sleep length were found for the subjects during the equinox (sunrise at 06:00 h) than under long-photoperiod conditions (sunrise at 04:00-05:00 h). During short-photoperiod conditions (sunrise at 07:00-10:00 h), no significant changes in the self-reported sleep-wake rhythm were found. The time of sunrise had the strongest impact on the sleep-wake rhythm of 30- to 97-yr-old persons. Sunrise had a stronger influence on chronotype and sleep length in January to May, when the days become longer, than in October to December, when the days become shorter. Age- and season-associated changes were found in the entrainment of the sleep-wake rhythm by photoperiod in the North.

Interaction of microbial β-glucuronidase with vegetable pectins

The purpose of this study was to investigate the in vitro effects of vegetable carbohydrates on the activity of microbial β-glucuronidase (βG) and the adsorption of the enzyme on carbohydrates. This study used pectin-protein complexes (PPCs) with molecular weights of 300 kDa isolated under conditions simulating a gastric environment from cabbage (HCl-PPCC and HCl+pepsin-PPCCP) and sweet pepper (PPCP and PPCPP). As a sample for comparison, microcrystalline cellulose was used. The activity of βG from Escherichia coli was determined spectrophotometrically by the formation of the colored product from the breakdown of phenolphthalein-β-D-glucuronide. Adsorption of βG on biopolymers was studied by the retention of the enzyme on the membrane of a concentrator with a pore diameter of 300 kDa and by native PAGE. PPCCP and PPCC were established to increase the activity of βG by 50 and 100%, respectively. Cellulose had a weak effect, whereas pepper PPC had no effect. All studied carbohydrates adsorb on βG. The maximum βG adsorption (15%) was observed with PPCC, whereas PPCCP absorbed 5% of the enzyme. Pepper PPCs and cellulose adsorbed up to 10% of the enzyme. There was a positive correlation between the increase of βG activity in the presence of carbohydrates and enzyme adsorption on the polymers (r=0.80; P<0.01). The activity of the enzyme in the gel after electrophoresis of the PPCC+βG mixture was inversely proportional to the concentration of PPCC in the mixture. A model explaining the effects of cabbage PPCs on the excretion of estrogens is proposed.

[Cancer risk in women: a possible connection with geographic and certain economic and social factors]

The paper deals with mulivariate regression analysis of effects of latitude, economic environment and electricity consumption on breast cancer morbidity in 35 countries (1985-2007). Our data are compared with the influence of the same factors on incidence rates for ovarian carcinoma, endometrial and cervical cancer as well as those of the stomach, liver, colon and lung. It was found that rates of morbidity for breast, endometrial, colonic and lung cancer tend to increase north of the equator while cervical, gastric and hepatic cancer incidence is relatively higher in circumequatorial populations. In 1985, geographic factors made a dramatic contribution to hormone-dependent tumors incidence while economic ones--to that of gastrointestinal neoplasms. In the 2000-ies, climate-related risks of hormone-dependent tumors have gradually slumped down while those of economic and social factors have increased.

Chronotype, sleep length, and school achievement of 11- to 23-year-old students in northern European Russia

Residing at northern latitudes for long periods of time is associated with sleep disturbances and internal desynchronization, which are considered to be causes of chronic diseases in old age. In children and teenagers, they result in a poor school achievement, psychological problems, and increase in consumption of stimulants. In this paper, we analyze the relationship between both chronotype and sleep length and the variables of age, sex, place of residence, type of settlement (village/city), latitude and longitude of residence, and school achievement of young inhabitants of northern European Russia. We surveyed 1101 children and teenagers between 11 to 23 yrs of age living in four settlements located between 59 degrees and 67 degrees North latitude and 33 degrees and 60 degrees East longitude. The Munich chronotype questionnaire (MCTQ) was used in the study, and all participants were also required to answer a question about their school achievements. An analysis of covariance (ANCOVA) was used to assess the influence of the analyzed factors on sleep length and chronotype. Self-reported sleep length of teenagers depended moderately on age, whereas the place of residence, latitude, and type of settlement only had a weak effect. Chronotype strongly depended on place of residence and longitude; it moderately depended on latitude and age; and it weakly depended on sex and type of settlement. The sleep length of village teenagers was 46 min longer than that of urban teenagers. The authors found a 1 h and 18 min phase delay of the sleep-wake rhythm (as a marker of chronotype) in teenagers moving in the East-West direction and a 16-min delay moving in the South-North direction within one time zone. There was a weak, but significant, positive correlation between chronotype and time of sunrise. There was about a 2-fold stronger influence of chronotype than sleep length on achievement of school children and college students. We conclude that socioeconomic factors exert a significant influence on sleep length and that climatic conditions exert a significant influence on the chronotype of teenagers in the northern latitudes.

[Chronotype of human in the north]

Long term acting climatic and social factors of the North causes desynchronization of human circadian system that can lead to increase in risk of age-associated diseases. Earlier on small sample we have shown, that the higher latitude of residing in the North, the higher rate of occurrence of late chronotype. It is noted also, that parameters of daily rhythm at late chronotype person are less expressed, than at early one. The purpose of present research is to study distribution of rates of various chronotypes depending on latitude of residing. Chronotypes were assessed by the Munich Chronotype Questionnaire (MCTQ). Our study includes 772 inhabitants of Komi Republic. It was shown that there is a significant shift to prevalence of late chronotype among inhabitants of the North. Thus, increase in rate of persons with late chronotype, circadian system of which is most sensitive to negative action climatic and social factors of the North, can be one of the causes of its desynchronization and increasing in risk of age-associated diseases at northerners.

[The effects of ultraviolet irradiation upon structure and antioxidant activity of silenan from bladder campion callus]

Effects of UV-B (280-315 nm) and UV-C (254 nm) at various doses upon callus of bladder campion (Silene vulgaris (M.) G. were studied. It was revealed that UV irradiation results in the decrease in arabinose and galactose residues in the silenan--the pectin fraction isolated from callus. The silenan possesses antioxidant activity (AOA) as assessed by the reaction with a stable radical. At the irradiation of callus by UV, the AOA of the silenan and the relative content of phenolic compounds in it increased; the highest increase was observed after the irradiation of callus by UV-B. Positive correlation between the AOA of the pectin fraction and an increase in phenolic compounds was revealed. This evidences that the AOA of the silenan relates to and is partially determined by phenolic compounds in its composition. The UV irradiation may be used as a tool to modify the structural features of the cell walls' polysaccharides in order to produce physiologically-active polysaccharides with desired properties.

[8-hour rhythm of ovarian progesterone secretion in ewe]

Pulse character of hormones secretion in the hypothalamus-pituitary-gonads system is a necessary condition of physiological regulation of reproduction. At the same time, the rhythms of ovarian hormones secretion have not been adequately explored. The researches study mainly three sexually mature ewes. The stages of oestrus cycle were determined on behavioral reactions of females in the presence of ram. Blood samples from jugular vein were collected hourly over 24-hour period during follicular (15-16 days), early (3-4 days) and middle (7-9 days) luteal phase of oestrus cycle, pregnancy (40-105 days) and lactation (30-45 days). 27 experiments were performed. Plasma progesterone was determined by enzyme-immunoassay method. There was no diurnal rhythm of ovarian progesterone secretion in ewes. During early and middle luteal phase of oestrus cycle and lactation, an 8-hour rhythm of progesterone secretion was detected. Follicular phase of oestrus cycle and pregnancy were characterized by irregular rises of fluctuations of progesterone level. It seems that the 8-hour rhythm of progesterone secretion during luteal phase and lactation is controlled by action of intraovarian generator of ultradian rhythms.

[Food lignins as natural geroprotectors]

Antioxidant properties of different botanic origin water soluble lignins are considered. Possibility to develop onco- and geroprotectors on the base of natural lignins is shown.

[Influence of light and electromagnetic radiation of Sun on circadian rhythms of the total antioxidant capacity of human saliva in the North]

The literature and results of own researches concerning the influence of climatic conditions of the North on human organism are analyzed in the paper. Experimental and clinical data are in accordance with a hypothesis of "circadian destruction" covering the mechanism of negative influence of factors of the North on human health. The model to describe the possible mechanism of action of electromagnetic radiations on circadian system of an organism is offered.

[Effect of natural light during "white nights" and melatonin on circadian rhythm of total antioxidant capacity of human saliva]

The results of our previous experiments indicate that total antioxidant capacity (TAC) of human saliva has a distinct circadian rhythm with maximum in the night and minimum in the daytime. The decrease of amplitude and other parameters of circadian rhythm of TAC of saliva in summer is marked. The aim of the present study was to evaluate an effect of light at night and exogenous melatonin (MT) on this parameter. There were 6 participants in experiments, at which 28 circadian rhythms have been analysed. The method of coulometric titration was used for measuring TAC of saliva. Light at night significantly decreases amplitude (P<0.001) and exogenous MT increases the level of AUC (P<0.05) and mesor (P<0.05). MT in vitro has a highest antioxidant activity among water soluble antioxidants tested (MT, quercetin, ascorbat, mitophen, white lignin, rutin). Pharmacological quantities of MT (0.1%) increases TAC of saliva in vitro as high as three times. The results of calculations indicate that specific TAC of MT is not enough to explain increase in TAC of saliva in vivo conditions. Consequently, MT stimulates biosynthesis and/or redistribution of low-molecular weight antioxidants in the human organism.

[Effect of Earth magnetic field on circadian rhythm of total antioxidant capacity of human saliva in the North]

In the inhabitants of the North during increase of geomagnetic activity and during magnetic calm the decrease of amplitude of circadian rhythm of total antioxidant capacity of saliva is observed. The most favorable conditions to display the circadian rhythm are observed at Kp from 0,5 up to 2. The long residing in the North is connected to influence of irregularly varying geomagnetic activity causing disturbance of function of circadian and antioxidant systems that, probably, is one of the reasons of acceleration of process of aging at northerner and of higher risk of occurrence in them the age associated diseases.

[Antioxidant status of ewe's blood during pregnancy and lactation]

Antioxidant status of ewe's blood during pregnancy and lactation was studied. It is revealed that the lipid peroxidation in erythrocytes is decreased, whereas in blood plasma is increased in the middle pregnancy, reaching the maximum shortly before peak of progesterone production. The activities of antioxidant enzymes are increased at the end of pregnancy, when the level of progesterone in blood is maximal. The positive correlation between plasma progesterone level and activity of erythrocyte superoxide dismutase (p < 0.01), between plasma cortisol concentration and total antioxidant capacity of blood plasma (p < 0.05) are revealed. It is shown, that the activities of antioxidant enzymes reach a maximum in the critical periods of pregnancy, providing the protection of the maternal organism and the fetus against negative influence of free radicals. The positive correlation between a level of hormones and separate parameters of antioxidant system in blood allows to assume, that progesterone participates in the regulation of enzymatic part of the antioxidant system, while cortisol is implicated in the regulation of the non-enzymatic component of this system in ewes.

[Dynamics of rumenoenteral transport of progesterone in sheep in chronic experiment]

In chronic experiments on pregnant and lactating sheeps with large fistula of rumen the dynamics of progesterone transport in a cavity of temporarily isolated reticulo-rumen depending on a physiological condition of animals, composition of solution filling a cavity of organ, and time of incubation, were studied. On three animals, 24 experiments were carried out. It was established that, during pregnancy, in a cavity of reticulo-rumen more progesterone was transported than during lactation (p < 0.05). Addition of lignin and cellulose to the salt solution increased the progesterone transport in the cavity of reticulo-rumen (p < 0.001). During three-hour incubation of salt solution in the cavity of reticulo-rumen, an increase of progesterone transport was observed in cavity of the organ (p < 0.001). The data obtained confirm the assumption that forestomach of ruminants participates in removing of progesterone from internal environment to enteral one and that carbohydrate polymers facilitate this process.

[Seasonal patterns of breast tumor growth in Far North residents]

Earlier, we established a relationship between sex hormone receptor concentration in tumor and 5-year survival, on the one hand, and seasonality, on the other. The parameters showed a distinct 6-month cycle. That pointed to certain environmental factors which could synchronize hormone-dependent tumor process in the breast of women living in the North. The present study is concerned with a relationship of 6-month rhythm of tumor growth and latitude of residence. Said rhythm was reliably identified as a parameter of 5-year survival in the Far North (68 deg. northern latitude, p < 0.001). Maximum values of 5-year survival were registered in those diagnosed with cancer in winter or summer, while those diagnosed in spring or fall had unfavorable prognosis. Northern magnetic storms recur at 6-month intervals and most frequently in spring and fall. Electromagnetic radiation is known to suppress melatonin production and, that might have stimulated tumor process. Therefore, it is most likely that solar electromagnetic radiation might synchronize hormone-dependent tumor process in women resident in the North.

[Progesterone transport across the wall of the rumen of sheep]

Data on content of fiber, lignin and progesterone in reticulo-ruminal chyme and progesterone in blood serum and saliva of sheep throughout the reproductive cycle and at intramuscular injection of progesterone, are presented. A direct correlation between concentration of progesterone in blood and chyme was revealed. 1.5% of progesterone entered the reticulo-rumen with saliva. Transport of hormone through the wall of forestomach is the main way of progesterone entering the reticulo-rumen. The transport is carried out against the gradient of hormone concentration. Possible participation of progesterone adsorption on lignin in explanation of this transport, is discussed.

[Correlation between sex hormone receptors in normal and cancerous target tissues]

According to the classic model of regulation of sex hormone receptors biosynthesis in target tissues, oestrogen stimulates and progesterone inhibits biosynthesis in both receptors. One of the consequences of this model is a direct correlation between oestrogen (ER) and progesterone receptors (PR) in target tissues. Here we investigate a correlation between ER and PR in calf endometrium and breast cancer (BC) tissues of women. A direct correlation was found between receptors in the calf endometrium (r = +0.70; p < 0.01). There were three variants of BC tissues: without correlation, with positive correlation (r = +0.49; p < 0.01), and with non-linear negative correlation between ER and PR. The last variant of samples were detected exclusively in patients operated in spring and fall. The non-linear negative correlation between ER and PR in BC tissues in spring and fall may indicate disregulation of sex hormone receptors biosynthesis under the influence of external factors.