Daytime Levels Research Articles

Light intensity and suppression of nocturnal plasma melatonin in Arctic charr (Salvelinus alpinus)

The problem of early sexual maturation among farmed Arctic charr and other salmonids can be effectively reduced by 24 h light overwinter, provided it is bright enough to over-ride interference from the natural daylength cycle. To determine the threshold light intensity to suppress the nocturnal elevation of plasma melatonin, three groups of individually tagged fish (n = 26–28/group ca. 1040 g) were reared on 12 h light: 12 h dark (LD 12:12) and subjected to nighttime light intensities of either 50–65, 0.1–0.3 or 0 (control) lux for five months (November to April). Daytime light intensity was 720–750 lx. Diel plasma melatonin profiles in both November and April were similar; mean daytime levels ranged from 20 to 100 pg/ml, and nighttime levels were inversely proportional to light intensity. In the control group at 0 lx, plasma melatonin increased about four-fold after lights-off, ranging between 320 and 430 pg/ml. Nighttime light intensity of 0.1–0.3 lx halved plasma melatonin levels to 140–220 pg/ml, and 50–65 lx further reduced the levels to one quarter of the control group, 68–108 pg/ml. Among the lit groups, daytime plasma melatonin levels were about 20–30 pg/ml, significantly lower than the nocturnal levels suggesting the diel hormonal rhythm was not completely abolished. Fish grew steadily from about 1100 g to 1600 g between November and April, independent of light intensity (P = .67). Overall, the study demonstrated the sensitivity of pineal melatonin hormone to different light intensities in Arctic charr.

Daytime HONO, NO<sub>2</sub> and aerosol distributions from MAX-DOAS observations in Melbourne

Abstract. Toxic nitrogen oxides produced by high temperature combustion are prevalent in urban environments, contributing to a significant health burden. Nitrogen oxides such as NO2 and HONO in pollution are important for hydroxyl radical (OH) production and overall oxidative capacity in urban environments; however, current mechanisms cannot explain high daytime levels of HONO observed in many urban and rural locations around the world. Here we present HONO, NO2 and aerosol extinction vertical distributions retrieved from multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements in suburban Melbourne, which are the first MAX-DOAS results from the Australian continent. Using the optimal estimation algorithm HEIPRO we show that vertical profiles for NO2 and HONO can be calculated with a low dependence on the retrieval forward model and a priori parameters, despite a lack of independent co-located aerosol or trace gas measurements. Between December 2016 and April 2017 average peak NO2 values of 8±2 ppb indicated moderate traffic pollution levels, and high daytime peak values of HONO were frequently detected, averaging 220±30 ppt in the middle of the day. HONO levels measured in Melbourne were typically lower than those recorded in the morning in other places around the world, indicating minimal overnight accumulation, but peaked in the middle of the day to be commensurate with midday concentrations in locations with much higher NO2 pollution. Regular midday peaks in the diurnal cycle of HONO surface concentrations have only previously been reported in rural locations. The HONO measured implies a daytime source term 1 ppb h−1 above the predicted photostationary state (PSS) concentration and represents an OH radical source up to 4 times stronger than from ozone photolysis alone in the lowest 500 m of the troposphere. The dependence of the high midday HONO levels on soil moisture, combined with the observed diurnal and vertical profiles, provides evidence for a strong photoactivated and ground-based daytime HONO source.

Abstract P100: Long-Term Exposures to Community Noise and Blood Pressure Levels in Chicago, Illinois

Objectives: Over half the US population experiences noise levels above WHO recommendations yet little research within the US has examined the health effects of these exposures. Our objective is to investigate the associations between community noise and blood pressure in residents of Chicago. Methods: Participants were from two prospective cohort studies: the Multi Ethnic Study of Atherosclerosis (MESA) and the Chicago Health and Aging Project (CHAP). MESA is a multi-site study of persons aged 45-84 years and free of clinical cardiovascular disease. CHAP is an open cohort initiated to study chronic conditions of aging among persons aged ≥65 years. This analysis focuses on the 5,167 participants of these cohorts living in Chicago with an average of 2.5 (CHAP) and 4.5 (MESA) assessments per participant, for systolic (SBP) and diastolic (DBP) blood pressure between 1999-2011. In both cohorts, hypertension was defined as taking antihypertensive medication, SBP ≥140 or DBP ≥ 90 mmHg. We estimated noise at participant addresses using land use regression models weighted according to participants’ 5-year residential history before each exam. Among those taking antihypertensive medication, blood pressure was adjusted using multiple imputation. Associations between noise and blood were estimated using linear mixed models. A Cox proportional hazards model was used to estimate relative risk (RR) of incident hypertension. All models included calendar time, age, sex, race, income, education, neighborhood socioeconomic score, smoking, cohort, interaction between cohort and age, race, and gender, and NO x (a traffic-related air pollutant). Findings : At baseline, MESA participants were younger (63 vs 73 years) and more educated (36 vs. 3% with ≥graduate degree) than CHAP participants. MESA participants had higher noise levels (60 vs 56 dB) and lower blood pressures (e.g. SBP: 124 vs 135 mmHg) than CHAP participants. After adjusting for cohort and other confounders, we found that 10 dB higher residential noise levels were associated with 0.9 (95% CI: -0.2, 0.2; p=0.1) and 0.5 mmHg greater (95% CI: -0.1, 0.11; p=0.08) SBP and DBP, respectively. Similar associations were found within each cohort. Noise was not associated with incident hypertension overall (RR: 1.00; 95% CI: 0.8, 1.3, p=0.98) or within cohort. Conclusions: We found a suggestive association between noise and blood pressure levels, but no association with hypertension. This could be due to the lack of nighttime noise information, which has been shown to be more strongly associated with blood pressure outcomes than daytime levels or with the selection of healthy older participants.

Night-time activation of the intrarenal renin-angiotensin system due to nocturnal hypertension is associated with renal arteriosclerosis in normotensive IgA nephropathy patients.

Intrarenal renin-angiotensin system (RAS) activation plays an important role in the development of hypertension and renal damage. However, the association between daytime and night-time intrarenal RAS activation and renal structural damage in normotensive IgA nephropathy patients is unclear. We investigated the relationships between urinary angiotensinogen (U-AGT) excretion, which reflects intrarenal RAS activity, and renal structural damage (i.e., endocapillary and mesangial cell hypercellularity, arteriolar hyalinosis and arteriosclerosis levels, and global glomerulosclerosis and tubulointerstitial fibrosis percentages) in 27 normotensive IgA nephropathy patients (age 39.2 ± 13.6 years, 10 men and 17 women, estimated glomerular filtration rate (eGFR) 74.0 ± 17.3 ml/min/1.73 m2, urinary protein excretion 0.58 ± 0.50 g/day, and U-AGT excretion 64.9 ± 100.6 μg/day). The arteriosclerosis level had a significant positive association with the daytime and night-time U-AGT excretion levels. By contrast, the endocapillary and mesangial cell hypercellularity and arteriolar hyalinosis levels and global glomerulosclerosis and tubulointerstitial fibrosis percentages did not correlate with the daytime and night-time U-AGT excretion levels. The daytime and night-time U-AGT excretion levels were higher in patients with arteriosclerotic changes than in patients without these changes. Multiple linear regression analysis revealed that the arteriosclerosis levels had a significant positive association with the U-AGT excretion levels at night after adjusting for age, sex, body mass index, and the eGFR. However, when diastolic BP was added as an independent variable, the relationship between U-AGT excretion and arteriosclerosis at night disappeared. In normotensive IgA nephropathy patients, intrarenal RAS activation at night due to nocturnal hypertension may be associated with arteriosclerosis.

Repetitive thought is associated with both subjectively and objectively recorded polysomnographic indices of disrupted sleep in insomnia disorder

BackgroundRepetitive thought is a hallmark of several psychopathological conditions and in particular a perpetuating and maintaining factor in Insomnia Disorder. Accordingly, one of the primary complaints reported by Insomnia patients is the inability to shut-off or control thoughts. Worry and rumination are the two best-known styles of repetitive thought leading to sleep disturbances. The aim of this study was to investigate the relationship of these two cognitive processes on nocturnal sleep indices objectively recorded by polysomnography. Methods27 Insomnia patients and 20 healthy controls matched for sex and age were recruited and completed a comprehensive assessment aimed to evaluate sleep quality, excessive daytime sleepiness, insomnia severity, worry, rumination, depressive and anxious symptomatology, and the ability to produce reasonable cognitive estimates. Sleep diaries indices and polysomnographic recordings were evaluated. ResultsInsomnia patients showed increased levels of worry and rumination in comparison to controls. Our polysomnographic study revealed that these two different types of repetitive thoughts were significantly associated with objective sleep variables. In particular, heightened worry levels were related to an augmented wake after sleep onset and diminished total sleep time, sleep efficiency and percentage of REM sleep, whereas rumination was associated with an increase of sleep latency and a decrement of sleep efficiency. However, after controlling for anxiety and depressive symptoms only worry maintained a significant relationship with polysomnographic variables. Remarkably, repetitive thoughts did not correlate with microstructural REM sleep features and quantitative EEG analysis. ConclusionOur study indicates the existence of a significant relationship between daytime levels of repetitive thought and sleep, thus corroborating the hypothesis of an interplay between cognitive and nocturnal electrophysiological activity in insomniacs.

Calibration and evaluation of CCD spectroradiometers for ground-based and airborne measurements of spectral actinic flux densities

Abstract. The properties and performance of charge-coupled device (CCD) array spectroradiometers for the measurement of atmospheric spectral actinic flux densities (280–650 nm) and photolysis frequencies were investigated. These instruments are widely used in atmospheric research and are suitable for aircraft applications because of high time resolutions and high sensitivities in the UV range. The laboratory characterization included instrument-specific properties like the wavelength accuracy, dark signal, dark noise and signal-to-noise ratio (SNR). Spectral sensitivities were derived from measurements with spectral irradiance standards. The calibration procedure is described in detail, and a straightforward method to minimize the influence of stray light on spectral sensitivities is introduced. From instrument dark noise, minimum detection limits ≈ 1 × 1010 cm−2 s−1 nm−1 were derived for spectral actinic flux densities at wavelengths around 300 nm (1 s integration time). As a prerequisite for the determination of stray light under field conditions, atmospheric cutoff wavelengths were defined using radiative transfer calculations as a function of the solar zenith angle (SZA) and total ozone column (TOC). The recommended analysis of field data relies on these cutoff wavelengths and is also described in detail taking data from a research flight on HALO (High Altitude and Long Range Research Aircraft) as an example. An evaluation of field data was performed by ground-based comparisons with a double-monochromator-based, highly sensitive reference spectroradiometer. Spectral actinic flux densities were compared as well as photolysis frequencies j(NO2) and j(O1D), representing UV-A and UV-B ranges, respectively. The spectra expectedly revealed increased daytime levels of stray-light-induced signals and noise below atmospheric cutoff wavelengths. The influence of instrument noise and stray-light-induced noise was found to be insignificant for j(NO2) and rather limited for j(O1D), resulting in estimated detection limits of 5 × 10−7 and 1 × 10−7 s−1, respectively, derived from nighttime measurements on the ground (0.3 s integration time, 10 s averages). For j(O1D) the detection limit could be further reduced by setting spectral actinic flux densities to zero below atmospheric cutoff wavelengths. The accuracies of photolysis frequencies were determined from linear regressions with data from the double-monochromator reference instrument. The agreement was typically within ±5 %. Because optical-receiver aspects are not specific for the CCD spectroradiometers, they were widely excluded in this work and will be treated in a separate paper, in particular with regard to airborne applications.

Determining the Pixel-to-Pixel Uncertainty in Satellite-Derived SST Fields

The primary measure of the quality of sea surface temperature (SST) fields obtained from satellite-borne infrared sensors has been the bias and variance of matchups with co-located in-situ values. Because such matchups tend to be widely separated, these bias and variance estimates are not necessarily a good measure of small scale (several pixels) gradients in these fields because one of the primary contributors to the uncertainty in satellite retrievals is atmospheric contamination, which tends to have large spatial scales compared with the pixel separation of infrared sensors. Hence, there is not a good measure to use in selecting SST fields appropriate for the study of submesoscale processes and, in particular, of processes associated with near-surface fronts, both of which have recently seen a rapid increase in interest. In this study, two methods are examined to address this problem, one based on spectra of the SST data and the other on their variograms. To evaluate the methods, instrument noise was estimated in Level-2 Visible-Infrared Imager-Radiometer Suite (VIIRS) and Advanced Very High Resolution Radiometer (AVHRR) SST fields of the Sargasso Sea. The two methods provided very nearly identical results for AVHRR: along-scan values of approximately 0.18 K for both day and night and along-track values of 0.21 K for day and night. By contrast, the instrument noise estimated for VIIRS varied by method, scan geometry and day-night. Specifically, daytime, along-scan (along-track), spectral estimates were found to be approximately 0.05 K (0.08 K) and the corresponding nighttime values of 0.02 K (0.03 K). Daytime estimates based on the variogram were found to be 0.08 K (0.10 K) with the corresponding nighttime values of 0.04 K (0.06 K). Taken together, AVHRR instrument noise is significantly larger than VIIRS instrument noise, along-track noise is larger than along-scan noise and daytime levels are higher than nighttime levels. Given the similarity of results and the less stringent preprocessing requirements, the variogram is the preferred method, although there is a suggestion that this approach overestimates the noise for high quality data in dynamically quiet regions. Finally, simulations of the impact of noise on the determination of SST gradients show that on average the gradient magnitude for typical ocean gradients will be accurately estimated with VIIRS but substantially overestimated with AVHRR.

Photosynthate partitioning to starch in Arabidopsis thaliana is insensitive to light intensity but sensitive to photoperiod due to a restriction on growth in the light in short photoperiods.

Photoperiod duration can be predicted from previous days, but irradiance fluctuates in an unpredictable manner. To investigate how allocation to starch responds to changes in these two environmental variables, Arabidopsis Col-0 was grown in a 6h and a 12h photoperiod at three different irradiances. The absolute rate of starch accumulation increased when photoperiod duration was shortened and when irradiance was increased. The proportion of photosynthate allocated to starch increased strongly when photoperiod duration was decreased but only slightly when irradiance was decreased. There was a small increase in the daytime level of sucrose and twofold increases in glucose, fructose and glucose 6-phosphate at a given irradiance in short photoperiods compared to long photoperiods. The rate of starch accumulation correlated strongly with sucrose and glucose levels in the light, irrespective of whether these sugars were responding to a change in photoperiod or irradiance. Whole plant carbon budget modelling revealed a selective restriction of growth in the light period in short photoperiods. It is proposed that photoperiod sensing, possibly related to the duration of the night, restricts growth in the light period in short photoperiods, increasing allocation to starch and providing more carbon reserves to support metabolism and growth in the long night.

Impact of age, sex and body mass index on cortisol secretion in 143 healthy adults.

ContextStudies on 24-h cortisol secretion are rare. The impact of sex, age and adiposity on cortisol levels, often restricted to one or a few samples, are well recognized, but conflicting.ObjectiveTo investigate cortisol dynamics in 143 healthy men and women, spanning 7 decades and with a 2-fold body mass index (BMI) range with different analytic tools.SettingClinical Research Unit.DesignCortisol concentrations in 10-min samples collected for 24 h. Outcomes were mean levels, deconvolution parameters, approximate entropy (ApEn, regularity statistic) and 24-h rhythms.ResultsTotal 24-h cortisol secretion rates estimated by deconvolution analysis were sex, age and BMI independent. Mean 24-h cortisol concentrations were lower in premenopausal women than those in men of comparable age (176 ± 8.2 vs 217 ± 9.4 nmol/L, P = 0.02), but not in subjects older than 50 years. This was due to lower daytime levels in women, albeit similar in the quiescent overnight period. Aging increased mean cortisol by 10 nmol/L per decade during the quiescent secretory phase and advanced the acrophase of the diurnal rhythm by 24 min/decade. However, total 24-h cortisol secretion rates estimated by deconvolution analysis were sex, age and BMI independent. ApEn of 24-h profiles was higher (more random) in premenopausal women than those in men (1.048 ± 0.025 vs 0.933 ± 0.023, P = 0.001), but not in subjects older than 50 years. ApEn peaked during the daytime.ConclusionSex and age jointly determine the 24-h cortisol secretory profile. Sex effects are largely restricted to age <50 years, whereas age effects elevate concentrations in the late evening and early night and advance the timing of the peak diurnal rhythm.

Daily Rhythm in Plasma N-acetyltryptamine.

Normal physiology undergoes 24-h changes in function that include daily rhythms in circulating hormones, most notably melatonin and cortical steroids. This study focused on N-acetyltryptamine, a little-studied melatonin receptor mixed agonist-antagonist and the likely evolutionary precursor of melatonin. The central issue addressed was whether N-acetyltryptamine is physiologically present in the circulation. N-acetyltryptamine was detected by LC-MS/MS in daytime plasma of 3 different mammals in subnanomolar levels (mean ± SEM: rat, 0.29 ± 0.05 nM, n = 5; rhesus macaque, 0.54 ± 0.24 nM, n = 4; human, 0.03 ± 0.01 nM, n = 32). Analysis of 24-h blood collections from rhesus macaques revealed a nocturnal increase in plasma N-acetyltryptamine (p < 0.001), which varied from 2- to 15-fold over daytime levels among the 4 animals studied. Related RNA sequencing studies indicated that the transcript encoding the tryptamine acetylating enzyme arylalkylamine N-acetyltransferase (AANAT) is expressed at similar levels in the rhesus pineal gland and retina, thereby indicating that either tissue could contribute to circulating N-acetyltryptamine. The evidence that N-acetyltryptamine is a physiological component of mammalian blood and exhibits a daily rhythm, together with known effects as a melatonin receptor mixed agonist-antagonist, shifts the status of N-acetyltryptamine from pharmacological tool to candidate for a physiological role. This provides a new opportunity to extend our understanding of 24-h biology.

Sleep in the Postpartum: Characteristics of First-Time, Healthy Mothers

Goals for the present study were to (a) describe the sleep of healthy new mothers over a 6-month postpartum period, (b) examine how sleep quality relates to daytime levels of fatigue and sleepiness, and (c) evaluate the relationship between mothers' and infants' sleep parameters. The sample consisted of 37 healthy, partnered, first-time mothers who had experienced full-term vaginal birth and had a healthy infant. We investigated infants' sleep parameters and mothers' sleep, mood, and daytime functioning 2 and 6 months postpartum. We found that at 2 months postpartum, mothers reported sleeping 6 hours at night and just under one hour during the day. Despite relatively frequent nocturnal awakenings, mothers experienced minimal insomnia, nonrefreshing sleep, anxiety, depression, daytime sleepiness, or fatigue at either 2 or 6 months. The most robust relationship between mothers' and infants' sleep was in the number of nocturnal sleep-wake episodes. Of note is that none of the infant sleep parameters was related to mothers' anxiety, depression, fatigue, sleepiness, or nonrefreshing sleep at either time period. Our results indicate that (1) selected low risk new mothers are resilient in terms of sleep quality, daytime functioning, and mood and (2) these are independent of their infants' sleep parameters.

Day-night variability of water-soluble ions in PM10 samples collected at a traffic site in southeastern Spain

The present work reports diurnal and nocturnal concentrations of water-soluble ions associated to PM10 samples collected during the warm and cold seasons in the urban center of Elche (Southeastern Spain). Statistical differences between daytime and nighttime levels of PM10 were only observed during winter. The lower concentrations during the night were most likely the result of a reduction in traffic-induced road dust resuspension, since nocturnal concentrations of calcium also exhibited a significant decrease compared to daytime levels. During the warm season, nitrate was the only component that showed a statistically significant increase from day to night. The lower nocturnal temperatures that prevent the thermal decomposition of ammonium nitrate and the formation of nitric acid favored by the higher relative humidity at night are the most probable reasons for this variation. The close relationship between nitrate formation and relative humidity during nighttime was supported by the results of the correlation analysis. The reaction of sulfuric and nitric acids with CaCO3 occurred to a greater extent during daytime in summer.

Ionospheric total electron content: Spatial patterns of variability

AbstractThe distinctive spatial patterns of the ionosphere's total electron content (TEC) response to solar, seasonal, diurnal, and geomagnetic influences are determined across the globe using a new statistical model constructed from 2‐hourly TEC observations from 1998 to 2015. The model combines representations of the physical solar EUV photon and geomagnetic activity drivers with solar‐modulated sinusoidal parameterizations of four seasonal cycles and solar‐modulated and seasonally modulated parameterizations of three diurnal cycles. The average absolute residual of the data‐model differences is 2.1 total electron content unit, 1 TECU = 1016 el m−2 (TECU) (9%) and the root‐mean‐square error is 3.5 TECU (15%). Solar and geomagnetic variability, the semiannual oscillation and the diurnal and semidiurnal oscillations all impact TEC most at low magnetic latitudes where TEC itself maximizes, with differing degrees of longitudinal inhomogeneity. In contrast, the annual oscillation manifests primarily in the Southern Hemisphere with maximum amplitude over midlatitude South America, extending to higher southern latitudes in the vicinity of the Weddell Sea. Nighttime TEC levels in the vicinity of the Weddell Sea exceed daytime levels every year in Southern Hemisphere summer as a consequence of the modulation of the diurnal oscillations by the seasonal oscillations. The anomaly, which is present at all phases of the solar cycle, commences sooner and ends later under solar minimum conditions. The model minus data residuals maximize at tropical magnetic latitudes in four geographical regions similar to the ionosphere pattern generated by lower atmospheric meteorology. Enhanced residuals at northern midlatitudes during winter are consistent with an influence of atmospheric gravity waves.

The acoustic environment of inpatient hospital wards in the United Kingdom.

Many hospital noise surveys have shown that patients are subject to high levels of noise, in excess of current World Health Organization guidelines. Much of the previous research has focused on areas perceived to be noisy, such as intensive care units and operating theatres. This paper presents the results of a comprehensive noise survey of five general inpatient hospital wards in the UK. The survey involved continuous noise monitoring over several days, including identification of noise sources, in 31 locations representing a range of typical patient accommodations including single rooms and multi-bed bays, and nurse stations. The results were consistent with those of previous studies with daytime levels ranging from 50 to 61 dB LAeq and nighttime levels from 41 to 51 dB LAeq. Noise levels were not correlated with room/bay size, with single rooms having some of the highest levels. Overall levels were related to reverberation times and to the numbers of high level noise events. Analysis of noise sources showed that much of the noise could be eliminated or reduced through improved design of equipment and ward layouts. In general, noise levels in wards built since the year 2000 were lower than those in the older buildings.

Circadian Rhythms in Water and Solute Handling in Adults with a Spinal Cord Injury

We evaluated nocturnal urine production and circadian rhythms of renal function (glomerular filtration, and water and solute diuresis) in adults with spinal cord injury compared to controls. This prospective observational study was done at Ghent University Hospital, Belgium. Participants were asked to perform a 24-hour urine collection. A blood sample was taken to calculate the diuresis rate and the renal clearance of creatinine, free water, solutes, sodium and urea. A total of 119 patients were divided into 32 with spinal cord injury, and 68 controls with and 19 without nocturnal polyuria. Spinal cord injured patients showed no circadian rhythms in the diuresis rate or in the renal clearance of creatinine, free water, solutes, sodium or urea. Controls without nocturnal polyuria reported a lower nighttime diuresis rate and lower nighttime clearance of creatinine, solutes, sodium and urea compared to daytime levels. Controls with nocturnal polyuria had no circadian rhythms in the diuresis rate or creatinine clearance and a significant increase in nocturnal free water clearance compared to daytime levels. Comparing the mechanisms underlying nocturnal urine production between patients with spinal cord injury and controls revealed important differences. Spinal cord injured patients showed absent circadian rhythms in the renal clearance of creatinine (glomerular filtration), free water (water diuresis) and solutes such as sodium and urea (solute diuresis). Future research must be done to evaluate the role of patient stratification to find the most effective and safe treatment or combination of treatments for spinal cord injured patients with complaints or complications related to nocturnal polyuria.

Natural melatonin fluctuation and its minimally invasive simulation in the zebra finch.

Melatonin is a key hormone in the regulation of circadian rhythms of vertebrates, including songbirds. Understanding diurnal melatonin fluctuations and being able to reverse or simulate natural melatonin levels are critical to investigating the influence of melatonin on various behaviors such as singing in birds. Here we give a detailed overview of natural fluctuations in plasma melatonin concentration throughout the night in the zebra finch. As shown in previous studies, we confirm that “lights off” initiates melatonin production at night in a natural situation. Notably, we find that melatonin levels return to daytime levels as early as two hours prior to the end of the dark-phase in some individuals and 30 min before “lights on” in all animals, suggesting that the presence of light in the morning is not essential for cessation of melatonin production in zebra finches. Thus, the duration of melatonin production seems not to be specified by the length of night and might therefore be less likely to directly couple circadian and annual rhythms. Additionally, we show that natural melatonin levels can be successfully simulated through a combination of light-treatment (daytime levels during subjective night) and the application of melatonin containing skin-cream (nighttime levels during subjective day). Moreover, natural levels and their fluctuation in the transition from day to night can be imitated, enabling the decoupling of the effects of melatonin, for example on neuronal activity, from sleep and circadian rhythmicity. Taken together, our high-resolution profile of natural melatonin levels and manipulation techniques open up new possibilities to answer various melatonin related questions in songbirds.

Observational Evidence for Involvement of Nitrate Radicals in Nighttime Oxidation of Mercury.

In the atmosphere, reactive forms of mercury species can be produced by oxidation of the dominant gaseous elemental mercury (GEM). The oxidation of GEM is an important driver for deposition, but oxidation pathways currently are poorly constrained and likely differ among regions. In this study, continuous measurements of atmospheric nitrate radical (NO3) concentrations and mercury speciation (i.e., elemental and reactive, oxidized forms) were performed during a six week period in the urban air shed of Jerusalem, Israel during summer 2012, to investigate the potential nighttime contribution of nitrate radicals to oxidized mercury formation. Average nighttime concentrations of reactive gaseous mercury (RGM) were almost equivalent to daytime levels (25 pg m(-3) and 27 pg m(-3) respectively), in contrast to early morning and evening RGM levels which dropped to low levels (9 and 13 pg m(-3)). During daytime, the presence of RGM was increased when solar radiation exceeded 200 W m(-2), suggesting a photochemical process for daytime RGM formation. Ozone concentrations were largely unrelated to daytime RGM. Nighttime RGM concentrations were relatively high (with a maximum of 97 pg m(-3)) compared to nighttime levels in other urban regions. A strong correlation was observed between nighttime RGM concentrations and nitrate radical concentration (R(2) averaging 0.47), while correlations to other variables were weak (e.g., RH; R(2) = 0.35) or absent (e.g., ozone, wind speed and direction, pollution tracers such as CO or SO2). Detailed analyses suggest that advection processes or tropospheric influences were unlikely to explain the strong nighttime correlations between NO3 and RGM, although these processes may contribute to these relationships. Our observations suggest that NO3 radicals may play a role in RGM formation, possibly due to a direct chemical involvement in GEM oxidation. Since physical data, however, suggest that NO3 unlikely initiates GEM oxidation, NO3 may play a secondary role in GEM oxidation through the addition to an unstable Hg(I) radical species.

EFFECTIVENESS OF PERINDOPRIL AND AMLODIPINE COMBINATION IN HYPERTENSIVES WITH COPD

Aim. To study efficacy of the standard combination of perindopril and amlodipine in target blood pressure levels achievement in COPD patients with AH. Material and methods. Totally 28 patients included 17 men and 11 women, mean age 51,42±1,45 y.o. with the COPD II-III stage established, with arterial hypertension II stage, 2 grade. In treatment we used fixed antihypertensive combination of ACE inhibitor and calcium channel blocker amlodipine. The values of “office BP” were measured, with ambulatory blood pressure monitoring and spirometry data. Results. After 30 days there was significant decrease of the mean “office BP” values, in 24 (85,7%) patients there was decrease of target BP. By ABPM data the decrease of mean clock-round, daytime and nocturnal BP values revealed. There was increase of the quantity of patients with physiological sleep pattern of BP from 5 to 12 (17,8% to 42,8%). Various dose regimens of perindopril/arginine combinations in 27 patients (96,4%) made it to achieve the BP level less than 140/90 mmHg. Long-term outcomes, tracked in the most of patients, showed good tolerability andhigh antihypertensive efficacy of the fixed perindopril and arginine combination. Conclusion. The use of fixed ACE inhibitor and calcium channel blocker combination fulfilled effective, dose dependent BP decrease and let most of COPD and AH patients reach the target BP. The treatment was followed by significant decrease of mean, daytime and nocturnal levels of ABPM. With the treatment there was recovery of physiological circle-round BP with reliable decrease at night. The possible side effect — dry cough — was rare and did not lead to the decrease of spirography parameters.

Introversion/extraversion Does Not Affect Serum Melatonin Levels

Introduction Few studies focus on peripheral biological markers of personality. Melatonin (MLT), the main hormonal product of the pineal gland, has been used both as a diagnostic and therapeutic element and has been related with chronotype, depression and schizophrenia, among other psychiatric conditions. However, there is a paucity of studies on its use as a personality marker. The present work aims to determine whether serum MLT levels are related with the Eysenck's personality extraversion/introversion (E/I) dimension. Methods A sample of 100 healthy volunteers participated in the study. The E/I personality dimension was evaluated using the EPQ-BV (Eysenck Personality Questionnaire – Brief Version). Three blood samples were taken (at 09:00, 12:00 and 00:00 h) to measure MLT. MLT was analysed in serum by an ELISA. Serum MLT concentrations are expressed in pg/ml. Results MLT levels displayed a clearly circadian pattern, with night levels being significantly higher than day-time levels (00:00: 35.78 ± 23.53 vs. 09:00: 7.78 ± 5.56, 12.00: 3.35 ± 1.94, p Conclusions There is no relationship between MLT levels and the E/I personality dimension. Future studies should examine the neuroticism dimension of personality.

Perceived racial discrimination and negative-mood-related drinking among African American college students.

Research consistently shows a positive association between racial discrimination and problematic alcohol use among African Americans, but little is known about the micro-processes linking this pernicious form of stress to drinking. One possibility is that the cumulative effects of discrimination increase individuals' likelihood of negative-mood-related drinking. In the current study, we examined whether individual differences in lifetime perceived racial discrimination among African American college students moderate relations between daily negative moods and evening alcohol consumption in both social and nonsocial contexts. Data came from an online daily diary study of 441 African Americans (58% female) enrolled at a historically black college/university. Lifetime discrimination was measured at baseline. For 30 days, students reported the number of drinks they consumed the night before both socially and nonsocially, as well as their daytime level of negative mood. In support of the hypotheses, only men who reported higher (vs. lower) lifetime discrimination showed a positive association between daily negative mood and that evening's level of nonsocial drinking. Contrary to expectation, women who reported higher (vs. lower) discrimination showed a negative association between daily negative mood and nonsocial drinking. Neither daily negative mood nor lifetime discrimination predicted level of social drinking. These findings provide further evidence that the cumulative impact of racial discrimination may produce a vulnerability to negative-mood-related drinking--but only for African American men. Importantly, these effects emerged only for nonsocial drinking, which may further explain the robust association between discrimination and problematic alcohol use.