Daytime Decrease Research Articles

Changes in 24-hour blood pressure profile after 12 weeks of dapagliflozin treatment in patients with diabetic kidney disease: an Italian multicenter prospective study.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) lower ambulatory blood pressure (ABP) in patients with type 2 diabetes mellitus; whether the same holds true in diabetic kidney disease (DKD) is unknown. This information is critical to the knowledge of mechanisms of nephroprotection and safety of this therapy. This multicenter prospective study evaluates the changes in ABP after 12weeks of dapagliflozin 10mg/day in a cohort of patients with type 2 DKD and glomerular filtration rate (GFR) >25mL/min/1.73 m2. Primary endpoint was the change of nighttime systolic blood pressure (SBP). Changes of daytime SBP, prevalence of normal dipping (day/night SBP ratio <0.9) and changes in ABP patterns, that is, sustained uncontrolled hypertension (SUCH), white coat uncontrolled hypertension (WUCH), masked uncontrolled hypertension (MUCH) and controlled hypertension (CH) were secondary endpoints. Eighty-three of 96 patients completed the study [age 68.7±8.9 years, 73.5% males, GFR 49±17mL/min/1.73 m2, median albuminuria: 0.18 (interquartile range 0.10-0.38) g/24h]. After 12weeks of dapagliflozin, nighttime SBP declined by -3.0mmHg (95% confidence interval -5.2/-0.8mmHg; P=.010) with an improvement of nighttime SBP goal (<110mmHg) from 18.0% to 27.0% (P<.001). Similarly, the prevalence of normal dipping increased (from 31.3% to 50.6%, P=.005). A decrease in daytime (-2.4mmHg; P=.046) and office (-7.9mmHg; P=.009) SBP was also found. The decline of ambulatory and office SBP was associated with increased prevalence of CH (from 6.0% to 18.0%) and significant improvement of SUCH, WUCH and MUCH (P=.009). Albuminuria decreased (P<.001), whereas eGFR did not change (P=.297). Urinary tract infection (4.2%) and acute kidney injury (3.6%) were the main causes of drop-out. Only one patient showed a drop of nighttime SBP below 90mmHg. Dapagliflozin is associated with improvement in circadian blood pressure rhythm with no major safety signal related to excessive blood pressure decrease.

Efficacy and safety of Pranabb® syrup to reduce cough and improve sleep quality in children compared to usual recommended hydration measures

Background: Coughing is crucial for protecting the airways, but associated to unpleasant symptoms that often lead to pediatrician visits. Natural remedies like honey and essentials oils are being increasingly used to effectively relieve symptoms associated with cough. Objectives: Evaluate the efficacy and safety of Pranabb® cough syrup, an organic honey-based natural formulation tailored for pediatric patients, in relieving cough symptoms. Methods: One-week multicenter comparative clinical study of 50 children, 28 in the treatment group and 22 in the control group with supportive measures (increased hydration). Pediatrician appointments were scheduled at the baseline and on day 7, with a progress check call on day 3. Parents kept a daily cough diary. Results: Day 3 results show a significant decrease in daytime cough, night-time cough and global score more pronounced and statistically significant in the study group, although the more severe baseline level in the study group. On day 7, decrease in daytime and overall cough scores was greater in the study group (p&lt;0.05). The frequency of awakenings due to coughing decreased on day 3 only in the study group (p&lt;0.05) and on day 7 for both groups, although it was higher and more significant in the study group (-1.82 p&lt;0.01 vs -1.25 p&lt;0.05). In addition, the safety analysis confirms that the syrup is not toxic to children. Conclusion: Pranabb® Cough Syrup is safe and effective, reducing cough severity and nighttime awakenings in children and improving parents’ ability to sleep. More randomized clinical trials will be interesting to get more homogeneity between the two groups at baseline.

Clinical, Metabolic and Neurohumoral Effects of L-arginine in Patients with Coronary Heart Disease in Combination with Arterial Hypertension

The objective: to analyze the impact of complex therapy using L-arginine, ubiquinone (coenzyme Q10), L-carnitine, lycopene, plant extracts and folic acid on the functional state of the endothelium, tolerance to physical activity, indicators of oxidative stress, lipid metabolism and clinical status patients with stable angina pectoris of the III functional class (FC) in comorbidity with arterial hypertension (AH) of the II grade, stage 2. Materials and methods. 100 patients with stable angina pectoris III FC and AH II grade, stage 2 aged 55–68 years participated in the study. The patients were divided into two groups: 50 patients of the 1st group received standard therapy – RAAS blocker, amlodipine, bisoprolol, acetylsalicylic acid and atorvastatin; 50 patients of the 2nd group in addition to standard therapy received a multi-component product of complex action, which includes L-arginine, ubiquinone (coenzyme Q10), Lcarnitine, lycopene, a number of plant extracts and folic acid, in a dose of 1 sachet per day. At the beginning and at the end of the study endothelial functions were assessed, daily blood pressure (BP) was monitored, physical exercise testing was performed, the weekly number of angina attacks and nitroglycerin tablet taking were recorded, oxidative status parameters were studied, quality of life was assessed, and the results were statistically processed. Results. The use of complex action preparation, which includes L-arginine, ubiquinone (coenzyme Q10), L-carnitine, lycopene, plant extracts and folic acid, as adjuvant therapy demonstrated a decrease in the level of indicators of lipid peroxidation (LPO) and an increase levels of antioxidant protection parameters. In the patients of the 2nd group a statistically significant positive dynamics of the blood pressure level was found: the median of daily systolic blood pressure (SBP) decreased to 131.78 mm (p&lt;0.01). A significant decrease in median daytime and nighttime SBP and diastolic blood pressure (DBP) was also determined (p&lt;0.01). The use of a multicomponent preparation of complex action led to a significant decreased of total cholesterol (CHL) by 14.5%, TG by 10.37% and low-density lipoprotein cholesterol by 12.5%. There was also an increased level of high-density lipoprotein cholesterol by 6.48% (р&lt;0.05 for all indicators). The patients of the 2nd group demonstrated a significant increase in tolerance to physical excesses: an increase in the double product by 21.4% and the total amount of the done work by 78.4% compared to the initial values (р&lt;0.05 for both indicators). After 2 months of treatment the difference between the groups in terms of the decrease in the weekly number of angina attacks was statistically significant (р&lt;0.05). This positive trend was accompanied by a decrease in the median number of nitroglycerin tablets taken per week in the 2nd group from 5.4 to 3.0 (р&lt;0.05). In the patients of the 2nd group after 2 months of observation a statistically significant improvement in quality of life indicators according to the “Seattle Angina Questionnaire” was determined (р&lt;0.05). Conclusions. Although all study participants received identical standard antihypertensive and lipid-lowering therapy, adjuvant use of a multicomponent complex of L-arginine, ubiquinone (coenzyme Q10), L-carnitine, lycopene, plant extracts, and folic acid for 2 months demonstrated a reduction in the impact of oxidative stress with parallel restoration of antioxidant mechanisms, improvement in vascular reactivity in patients and daily control of blood pressure, contributed to the correction of the lipid profile with increased tolerance to physical exercise and, as a result of the above-mentioned effects, had a significant positive impact on the quality of life of patients.

The proposed model for analyzing off-street parking Dynamics: A case study of Taipei City

To reduce traffic congestion, air pollution, and lost revenue due to wasted driving around looking for parking spaces, effective parking management has become a crucial issue in urban areas. Previous studies have shown that parking demand is related to the location of parking spaces/lots, parking fees, time spent looking for spaces, and various driver and environmental characteristics. However, there have been more studies of on-street rather than off-street parking. Also, the spatio-temporal variance between variables and turnover rate (such as the hours of operation for various types of Points of Interest (POIs) as well as the causes of bias estimators has been largely overlooked.To solve the above problems, the Geographical and Temporal Weighted Regression (GTWR) model was utilized in this study to predict the hourly parking turnover rate in off-street parking lots. The flexible coefficient setting of this model can be used to capture the spatial and temporal variance. In addition to this model, the Geographically Weighted Regression (GWR) and the Ordinary Least Squares (OLS) models were used as a basis for comparison. The study included 346 public off-street parking lots in Taipei and 10 types of nearby POIs. The study period was for 24 h on August 31, 2021. Due to the dissimilar trend of the turnover rate, the researchers separated all parking lots into three groups for regression analysis: those that experience a daytime decrease, remain stable, and those with an increase during the day.Our results show the following: (1) For the types of parking lots that experienced increases and decreases, the GTWR model performed best for the prediction of hourly turnover rate, while all models performed similarly for the prediction of the stable type parking lot. (2) With regard to related factors (the type 1 parking lot for example), parking lots in areas with more traditional markets, MRT stations, and with fewer schools, supermarkets, hotel bus stops, and lower parking fees tended to have higher turnover rates. (3) Incorporating a more precise POI dataset (the number and types of POIs as well as their business hours) and applying a suitable spatial temporal model improved the parking demand model’s performance. However, the GTWR model’s limitations may hamper its performance, especially with regard to analysis of the time-stable parking lots or variables. Future studies might include other datasets, such as nearby private parking lots or holiday data to improve the model fit.

Ligustrum lucidum invasion alters the soil water dynamic in a seasonally multi-specific dry forest

Plant invasion is one of the major global environmental threats with the potential to alter the ecosystem stability and functioning. In water-limited ecosystems, the impacts of non-native invasive trees on the water balance are particularly relevant since they can compromise the use of water by native taxa of the ecosystem and water provision for humans. In this paper, we assessed the hydrological impacts of the Ligustrum lucidum (Chinese glossy privet) invasion on a mountain seasonally dry forest of the Chaco region (Central Argentina). More specifically, we determined volumetric soil water content, runoff, and actual evapotranspiration, and their relations to the size of rainfall events in native forest stands and its adjacent invaded stands. We combined three-years field measurements and remote sensing data. L. lucidum stands showed less water content through the soil profiles than the native forest (0–70 cm depth; 19.6 and 23.1 %, respectively), particularly during the dry conditions. The drier condition in the deeper soil layers compared to the upper ones in the invaded stands indicated less rainwater percolation throughout the soil profile over the year, independently of the magnitude of the rainfall events. Daily variation of deep-water content (60–70 cm depth), only observed in L. lucidum stands, showed nightly increase and day-time decrease in dry conditions. Runoff was similar and almost nil in both native and invaded forests, even after large rainfall events (>30 mm). L. lucidum stands showed ∼ 18% higher annual actual evapotranspiration rates than native stands. Based on our results, relatively higher water consumption for mono-specific L. lucidum stands in periods when photosynthetic activity of multi-specific native dry forest is still low may represent a competitive advantage in terms of plant invasion, and at the same time it generates negative impacts on water resources, reducing soil water content and limiting deep-water recharge in a water-limited ecosystem.

A multi-year study of ecosystem production and its relation to biophysical factors over a temperate peatland

Peatlands are among the largest stocks of soil carbon, which can be stored for thousands of years under well-wetted conditions. The main goals of the study were to assess annual and seasonal CO2 balances of a temperate peatland and the main biophysical factors affecting these CO2 fluxes. The studied peatland was usually a CO2 sink with a mean annual net ecosystem production (NEP) of 110±83 gCO2-C·m−2·yr−1 and extreme balances in 2006 (-17 gCO2-C·m−2·yr−1) and 2011 (194 gCO2-C·m−2·yr−1). Annual fluxes were not significantly correlated with biophysical variables, unlike seasonal data. Furthermore, the average air temperature in spring and summer was related to NEP at r2=0.65 and r2=0.61, respectively (warmer spring increased NEP while hot summer decreased NEP in these seasons). A decrease in daytime measured NEP during the summer period (June-August) was observed when TA exceeded 25 °C or VPD was above 15 hPa, respectively, due to the growing Reco and possibly plant photorespiration. These findings suggest a negative impact of ongoing global warming on temperate peatland CO2 balances.

Changes in day–night dominance of combined day and night heatwave events in China during 1979–2018

China has experienced varying degrees of increase or decrease in daytime and nighttime heatwaves, but studies have mostly been at the site or grid scale, and it remains unclear how daytime and nighttime heatwave events in China vary regionally when spatial scales are considered. Here, we redefine the different types of heatwave events in China from 1979 to 2018 as combined day and night heatwave events (CDNHWEs) and independent daytime (nighttime) heatwave events. Due to more pronounced spatiotemporal characteristics, CDNHWEs are the dominant heatwave events in China. Further analysis of the dominant heatwave events indicates that their increase in intensity is stronger at night than during the day, i.e. for CDNHWEs, the daytime-dominated events are gradually replaced by nighttime-dominated events. Compared to 1979–2003, there has been an increase in dominant heatwave events mainly in the south during the day and a nationwide increase at night since 2004. For CDNHWEs, daytime and nighttime processes are regulated by different mechanisms. During the daytime, fewer clouds enhance solar shortwave radiation, favouring daytime heatwaves; however, the increase in aerosols in northern China suppresses solar shortwave radiation. At night, the increase in humidity allows for increased longwave radiation, which favours the formation of nighttime heatwaves across the country. These findings further demonstrate the regional variability of heatwave hazards experienced in China and that targeted heatwave-mitigation measures should be developed based on regional characteristics.

14 THE THERAPEUTIC VALUES OF CATHETER-BASED RENAL DENERVATION PROCEDURE AGAINST RESISTANT HYPERTENSION IN PATIENTS WITH OR WITHOUT CHRONIC KIDNEY DISEASE: REVISITING THE PROMISING PROSPECT - A SYSTEMATIC REVIEW AND META-ANALYSIS

Background: The increasing incidence of uncontrolled hypertension despite a greater number of therapies has been described as the “hypertension paradox”. CKD often complicates antihypertensive treatment by rendering the disease resistant to treatment. Recently, catheter-based renal denervation has reemerged as potential treatment for resistant hypertension. Several trials reported significant SBP-lowering effects in patients treated with catheter-based renal denervation. Objective: This meta-analysis aims to summarize the antihypertensive properties of renal denervation to control SBP in patients with resistant hypertension with CKD. Methods: Systematic review and meta-analysis were conducted with literatures from ProQuest, Elsevier, SpringerLink, and Oxford Academic to PRISMA Guidelines for RCTs regarding SBP management with renal denervation for resistant hypertension patients with or without CKD using Renal Denervation, Resistant Hypertension, Systolic Blood Pressure and Chronic Kidney Disease as keywords. Results: Six literatures were analyzed, consisting of 730 patients with resistant hypertension with or without CKD. The subjects underwent catheter-based renal denervation in comparison to sham procedures, in RCTs for 2-12 months. These trials exhibit beneficial antihypertensive effects of renal denervation, reducing the ambulatory 24-hour SBP (MD -8.5[-15.1 to 0.0] vs. MD -2.9[-12.6 to 2.5]; p=0.016) 2-months post-procedure. Other literatures also reported major office SBP decrease (180 mmHg ±12 to 149.0 mmHg ±11 vs. 181.0 mmHg ±19 to 179.0 mmHg ±5; p=0.007) 12-months post-procedure. Another shows significant decrease in daytime (MD -12mmHg ±18; p&lt;0.001) and nighttime (MD -8mmHg ±19; p&lt;0.013) SBP. Conclusion: Renal denervation showed significant SBP lowering effects in patients with resistant hypertension based on evidences exhibited. Further research is necessary to provide more evidence to support this outcome.

Circadian Rhythms of Perineuronal Net Composition

Perineuronal nets (PNNs) are extracellular matrix (ECM) structures that envelop neurons and regulate synaptic functions. Long thought to be stable structures, PNNs have been recently shown to respond dynamically during learning, potentially regulating the formation of new synapses. We postulated that PNNs vary during sleep, a period of active synaptic modification. Notably, PNN components are cleaved by matrix proteases such as the protease cathepsin-S. This protease is diurnally expressed in the mouse cortex, coinciding with dendritic spine density rhythms. Thus, cathepsin-S may contribute to PNN remodeling during sleep, mediating synaptic reorganization. These studies were designed to test the hypothesis that PNN numbers vary in a diurnal manner in the rodent and human brain, as well as in a circadian manner in the rodent brain, and that these rhythms are disrupted by sleep deprivation. In mice, we observed diurnal and circadian rhythms of PNNs labeled with the lectin Wisteria floribunda agglutinin (WFA+ PNNs) in several brain regions involved in emotional memory processing. Sleep deprivation prevented the daytime decrease of WFA+ PNNs and enhances fear memory extinction. Diurnal rhythms of cathepsin-S expression in microglia were observed in the same brain regions, opposite to PNN rhythms. Finally, incubation of mouse sections with cathepsin-S eliminated PNN labeling. In humans, WFA+ PNNs showed a diurnal rhythm in the amygdala and thalamic reticular nucleus (TRN). Our results demonstrate that PNNs vary in a circadian manner and this is disrupted by sleep deprivation. We suggest that rhythmic modification of PNNs may contribute to memory consolidation during sleep.

0639 Long Term Oral Appliance Therapy Decreases Stress Symptoms In Upper Airway Resistance Syndrome Patients

Abstract Introduction Upper Airway Resistance Syndrome (UARS) is suspected in individuals with excessive daytime sleepiness, fatigue and sleep fragmentation due to increased respiratory effort. UARS can negatively impact daytime function and decrease quality of life. Cognitive impairment in UARS patients has not been well stablished yet. The objective of the study was to evaluate the long-term effects of a mandibular advancement device (MAD) on cognitive function in patients with UARS compared with placebo. Methods This study was a randomized placebo-controlled clinical trial. Thirty UARS patients were randomized in two groups: placebo and MAD groups. UARS criteria were the presence of sleepiness (Epworth Sleepiness Scale ≥ 10) and/or fatigue (Modified Fatigue Impact Scale ≥ 38) associated with an apnea/hypopnea index (AHI) ≤ 5 and a respiratory disturbance index (RDI) &amp;gt; 5 events/hour of sleep, and/or flow limitation in more than 30% of total sleep time. All patients completed the Rey Auditory-Verbal Learning Test (RAVLT), the Logical Memory Test, the Stroop Color Test, the Trail Making Test, the Digit Symbol Substitution Test and Inventory of Stress Symptoms (Lipp test). Cognition protocol was defined based on most used neuropsychological tests in the literature. Evaluations were performed before and after 1.5 years of treatment. Results There was no statistically significant difference in RAVLT, Logical Memory Test, Stroop Color Test, Trail Making Test, Digit Symbol Substitution Test before and after 1.5 year of treatment in both groups. The Lipp test score decreased at alarm phase (p = 0.05) and at resistance phase (p = 0.01) after 1.5 year of MAD treatment compared to placebo. Conclusion Mandibular advancement device was effective in decreasing stress symptoms in alarm and resistance phases of Lipp test in UARS patients after 1.5-years of MAD treatment. Support The authors would like to thank for the support by grants from Associação Fundo de Incentivo a Pesquisa (AFIP), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

Ten‐year changes in ambulatory blood pressure: The prognostic value of ambulatory pulse pressure

Blood pressure (BP) changes and risk factors associated with pulse pressure (PP) increase in elderly people have rarely been studied using ambulatory blood pressure monitoring (ABPM). The aim is to evaluate 10-year ambulatory blood pressure (ABP) changes in older hypertensives, focusing on PP and its associations with mortality. An observational study was conducted on 119 consecutive older treated hypertensives evaluated at baseline (T0) and after 10years (T1). Treatment adherence was carefully assessed. The authors considered clinical parameters at T1 only in survivors (n=87). Patients with controlled ABP both at T0 and T1 were considered as having sustained BP control. Change in 24-hour PP between T0 and T1 (Δ24-hour PP) was considered for the analyses. Mean age at T0: 69.4±3.7years. Females: 57.5%. Significant decrease in 24-hour, daytime, and nighttime diastolic BP (all P<.05) coupled with an increase in 24-hour, daytime, and nighttime PP (all P<.05) were observed at T1. Sustained daytime BP control was associated with lower 24-hour PP increase than nonsustained daytime BP control (+2.23±9.36 vs +7.79±8.64mmHg; P=.037). The association between sustained daytime BP control and Δ24-hour PP remained significant even after adjusting for age, sex, and 24-hour PP at T0 (β=0.39; P=.035). Both 24-hour systolic BP and 24-hour PP at T0 predicted mortality (adjusted HR 1.07, P=.001; adjusted HR 1.25, P<.001, respectively). After ROC comparison (P=.001), 24-hour PP better predicted mortality than 24-hour systolic BP. The data confirm how ABP control affects vascular aging leading to PP increase. Both ambulatory PP and systolic BP rather than diastolic BP predict mortality in older treated hypertensives.

Variations in Ionospheric Peak Electron Density During Sudden Stratospheric Warmings in the Arctic Region

AbstractThe focus of the paper is the ionospheric disturbances during sudden stratospheric warming (SSW) events in the Arctic region. This study examines the ionospheric behavior during 12 SSW events, which occurred in the Northern Hemisphere over 2006–2013, based on vertical sounding data from DPS‐4 ionosonde located in Norilsk (88.0°E, 69.2°N). Most of the addressed events show that despite generally quiet geomagnetic conditions, notable changes in the ionospheric behavior are observed during SSWs. During the SSW evolution and peak phases, there is a daytime decrease in NmF2 values at 10–20% relative to background level. After the SSW maxima, in contrast, midday NmF2 surpasses the average monthly values for 10–20 days. These changes in the electron density are observed for both strong and weak stratospheric warmings occurring at midwinter. The revealed SSW effects in the polar ionosphere are assumed to be associated with changes in the thermospheric neutral composition, affecting the F2‐layer electron density. Analysis of the Global Ultraviolet Imager data revealed the positive variations in the O/N2 ratio within the thermosphere during SSW peak and recovery periods. Probable mechanisms for SSW impact on the state of the high‐latitude neutral thermosphere and ionosphere are discussed.

A study of the combined impact of boundary layer height and near-surface meteorology on the CO diurnal cycle at a low mountaintop site using simultaneous lidar and in-situ observations

Evaluations of air pollutants and trace gas measurements over mountaintop sites and their application in inverse transport models to estimate regional scale fluxes are oftentimes challenging due to the influences associated with atmospheric transport at both local and regional scales. The objective of this study is to investigate the diurnal cycle pattern of CO mixing ratio over a low mountaintop influenced by: (1) two different convective boundary layer (CBL) regimes (shallow and deep) and associated growth rates over the mountaintop, (2) the combined effect of a deep CBL with and without diurnal wind shift, and (3) slope flows and associated air mass transport. For this purpose, we used simultaneous measurements of lidar-derived CBL heights, standard meteorological variables, and CO2 and CO mixing ratio from Pinnacles, a mountaintop monitoring site in the Appalachian Mountains. We used both water vapor and CO2 mixing ratio as tracers for upslope flow air masses. We used case studies to focus on two different scenarios of daytime CO mixing ratio variability: (1) a gradual increase in the morning with a maximum in the afternoon, and (2) a gradual decrease in the morning with a minimum in the late afternoon. The second scenario is similar to the CO variability observed atop tall towers in flat terrain.Using the lidar-derived CBL height evolution and in situ CO, CO2 and meteorological measurements over the mountaintop, we found that the CBL height dynamics, regional scale wind shift, and upslope flow air masses arriving at the mountaintop in the morning affect the CO mixing ratio variability during the remaining part of the diurnal cycle. These findings help introduce a conceptual framework that can explain and differentiate the opposite patterns (i.e. daytime increase versus daytime decrease) in the CO diurnal cycles over a mountaintop site affected by upslope flows and provide new roadmaps for monitoring and assimilating trace gas mixing ratios into applications requiring regionally-representative measurements.

Diel cycling and flux of HCO3− in a typical karst spring-fed stream of southwestern China

We investigated the diel variations of the dissolved inorganic carbon, isotopic composition, and partial CO2 pressure from a karst spring (Guangcun Village, Guangxi, Southwest China) to the 1,350 m downstream profile of the stream. In addition, the carbon loss and CO2 exchange flux at the water-gas interface were also estimated. The results showed that the pH value and DO in the stream varied regularly on a daily basis with the temperature of stream water, suggesting that the photosynthesis of aquatic plants and algae is the controlling factor for the diel variations of the pH and DO. During the monitoring period, while the DIC (mainly in HCO3−) input (at spring) was relatively stable at about 4.46 mmol L−1, the concentrations of HCO3− and Ca2+ at downstream showed a diel cycle of daytime decrease and nighttime increase, with an amplitude of 22.4 %. We also found out that the CO2 degassing mainly occurred in the upper reach of the surface stream right after groundwater is exposed to the surface. The total CO2 exchange flux of the entire monitoring stream section was calculated to be 29.83 kg d−1, accounting for 17.8 % of the DIC loss, which means that approximately 4/5 of the loss was converted into organic carbon or calcite precipitation. Compared with the total carbon input at spring, this carbon loss only accounts for 6.5 % of the total carbon amount (1.4 % of which was converted into organic carbon and 1.1 % of which was degassed to the atmosphere), indicating that the DIC of karst groundwater in low order surface stream of Guancun is stable in general, with 1 % being lost to the atmosphere. This suggests that on a daily timescale, carbon loss in the form of CO2 of low order karst streams with lower gradient is much less pronounced. Key words: inorganic carbon cycle, spring-fed stream, aquatic vegetation photosynthesis, CO2 degassing, inorganic carbon flux, karst.

Abstract # 1730 Cytotoxic T cells of different antigen specificity are differentially regulated by the circadian system in humans

In humans, the numbers of cytotoxic T lymphocytes (CTLs) in blood display a strong circadian rhythm with a steep decrease from night to daytime. However, CTLs are composed of various subsets and exert antigen-specific responses which are highly adapted to the specific pathogen. We therefore investigated whether CTL subpopulations of distinct antigen-specificity are differentially regulated by the circadian system. To this aim, we analyzed influenza virus (FLU)-specific CTLs and CTLs specific for cytomegalovirus (CMV), which induces a chronic but latent infection. FLU-/CMV-specific CTLs and subsets were quantified every 4 h over a 24-h period in selectively recruited CMV-positive men and women. Preliminary analyses confirmed the daytime decrease of total circulating CTLs. FLU-specific CTLs followed this circadian rhythm. However, CMV-specific CTL numbers remained constant over 24 h and their fraction within total CTLs even increased during daytime. A similar difference between FLU- and CMV-specific CTLs was also evident when analyzing the different subpopulations: FLU-specific CTLs were central memory, effector memory and effector cells, which all presented a pronounced decline from night to daytime. In contrast, CMV-specific CTLs were mainly effector memory and effector cells, which remained stable over 24 h. Although the study is still ongoing, these preliminary results suggest that CTLs specific for different viruses are differentially regulated by the circadian system which might represent a further adaptation to the specific pathogen they target.

Sexually dimorphic and interactive effects of prenatal maternal cortisol and psychological distress on infant cortisol reactivity.

In utero exposure to maternal psychological distress is a risk factor for developmental psychopathology, and these effects are believed to partially occur via dysregulation of the maternal and fetal hypothalamus-adrenal-pituitary axes. Nevertheless, only a few human studies have directly assessed the effects of prenatal cortisol exposure on infant cortisol reactivity, and none have investigated sex differences or potential interactions between prenatal cortisol and psychological distress. Here we report on a prospective longitudinal investigation (N = 236) of in utero exposure to maternal cortisol and distress in a relatively high socioeconomic status and low-risk population to determine whether these exposures interact in their effects on infant (M age = 3.0 months, range = 2.3-5.0 months, 51.9% male) cortisol reactivity and whether there are sex differences in these effects. Results revealed both sexually dimorphic and interactive effects of prenatal cortisol and distress, even after controlling for postnatal distress. In general, blunted reactivity in females was associated with exposure to high maternal distress and flattened patterns of diurnal maternal cortisol, whereas blunted reactivity in males was associated with exposure to steeper morning increases and daytime decreases in maternal cortisol. The findings suggest that sex differences in the effects of prenatal cortisol and distress on infant cortisol reactivity are a plausible mechanism by which maternal experiences during pregnancy contribute to sex differences in the development of psychopathology.

Nocturnal Blood Pressure Dipping in Normotensive Adults: Effect of Dietary Sodium and Sex

Normal nocturnal blood pressure (BP) dipping is arbitrarily defined as a decrease in mean daytime to mean nighttime BP by 10% to 20%. Individuals that have impaired nocturnal BP dipping (i.e., &lt;10%) have an increased risk of cerebrovascular and cardiovascular diseases. Excess sodium consumption is associated with increased cardiovascular disease risks and no studies have examined nocturnal BP dipping under a controlled sodium diet.PURPOSETo assess nocturnal BP dipping during low (LS) and high sodium (HS) diets in men and women. We hypothesized that a HS diet would impair nocturnal BP dipping, and men would have a greater impairment than women.METHODSEighty‐seven healthy normotensive men (n = 41; age: 35 ± 2 years) and women (n = 46; age: 40 ± 2 years) participated in a controlled feeding study where LS (20 mmol Na+/day) and HS (300 mmol Na+/day) diets were provided for 7 days each in random order. Subjects wore a 24‐hour ambulatory BP monitor, and we collected a 24‐hour urine sample and fasted blood sample on the final day of each diet. Nocturnal BP dipping was calculated as: ((mean daytime BP – mean nighttime BP)/mean daytime pressure)*100.RESULTSAs expected, there was a significant increase in urinary sodium excretion during the HS diet (women: LS = 26.0 ± 2.1 vs. HS = 238.4 ± 14.1 mmol/24hr; men: LS = 31.5 ± 4.4 vs. HS = 234.4 ± 13.3 mmol/24hr; p &lt; 0.01) and serum sodium (women: LS = 137.7 ± 0.3 vs. HS = 139.7 ± 0.2 mmol/L; men: LS 137.9 ± 0.4 vs. HS = 139.8 ± 0.3; p &lt; 0.05) with no differences observed between the sexes. Nocturnal BP dipping was not different between the diets (women: LS = 10 ± 1% vs. HS = 10 ± 1% mmHg; men: LS = 9 ± 1% vs. HS = 10 ± 1% mmHg; p &gt; 0.05) with no differences observed between the sexes.CONCLUSIONOur findings suggest that increased dietary sodium does not influence nocturnal BP dipping responses in normotensive men and women.Support or Funding InformationNIH Grant R01 HL104106

Sleep variability and cardiac autonomic modulation in adolescents – Penn State Child Cohort (PSCC) study

ObjectiveTo investigate the effects of objectively measured habitual sleep patterns on cardiac autonomic modulation (CAM) in a population-based sample of adolescents. MethodsWe used data from 421 adolescents who completed the follow-up examination in the Penn State Children Cohort study. CAM was assessed by heart rate (HR) variability (HRV) analysis of beat-to-beat normal R-R intervals from a 39-h electrocardiogram, on a 30-min basis. The HRV indices included frequency domain (HF, LF, and LF/HF ratio), and time domain (SDNN, RMSSD, and heart rate or HR) variables. Actigraphy was used for seven consecutive nights to estimate nightly sleep duration and time in bed. The seven-night mean (SD) of sleep duration and sleep efficiency were used to represent sleep duration, duration variability, sleep efficiency, and efficiency variability, respectively. HF and LF were log-transformed for statistical analysis. Linear mixed-effect models were used to analyze the association between sleep patterns and CAM. ResultsAfter adjusting for major confounders, increased sleep duration variability and efficiency variability were significantly associated with lower HRV and higher HR during the 39-h, as well as separated by daytime and nighttime. For instance, a 1-h increase in sleep duration variability is associated with −0.14(0.04), −0.12(0.06), and −0.16(0.05) ms2 decrease in total, daytime, and nighttime HF, respectively. No associations were found between sleep duration, or sleep efficiency and HRV. ConclusionHigher habitual sleep duration variability and efficiency variability are associated with lower HRV and higher HR, suggesting that an irregular sleep pattern has an adverse impact on CAM, even in healthy adolescents.

Arctic Diurnal Land-Surface Temperature Range Changes Derived by NASA MODIS-Terra and -Aqua 2000 through 2012

The diurnal variation of surface temperature is a fundamental parameter as it is a driver of physical processes of atmosphere-land and -ocean energy and mass cycles playing a key role in meteorology and climatology. Our investigation focus is on the diurnal variation of land-surface temperature derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) deployed on the NASA Terra and Aqua satellites. We key our investigation on the ascending and descending mode equator crossing times for daytime and nighttime land-surface temperature variations from March 2000 through 2010 (MODIS-Terra) and July 2002 through 2012 (MODIS-Aqua) and assess the diurnal land-surface temperature range changes at those sampling times. Our investigation shows non-stationary changes in the trends of land-surface temperature diurnal range. We identify changes in the diurnal range trends linked to increase of daytime and nighttime land-surface temperatures from March 2000 through 2010 and decrease in daytime and nighttime land-surface temperatures from July 2002 through 2012. The most recent decrease in daytime and nighttime land-surface temperatures and diurnal range will affect Arctic and other associated energy and mass cycles.

Hypoglycaemia is associated with the absence of a decrease in diurnal macular thickness in patients with diabetic macular oedema

AimSpontaneous diurnal variations measured by optical coherence tomography (OCT) have been reported in diabetic macular oedema (DME) together with a daytime decrease in central macular thickness (CMT). For this reason, this study aimed to investigate the influence of acute glucose and blood pressure changes on daytime variations in CMT in patients with DME. MethodsIn this prospective observational study of type 1 (n=4) and type 2 (n=18) diabetic patients with DME, OCT scans, capillary blood glucose, and systolic and diastolic blood pressure measurements were performed at 9 a.m., 12 a.m., 3 p.m., 6 p.m. and again at 9 a.m. the day after. At the same time, the study protocol included simultaneous ambulatory blood pressure and glucose monitoring over a 24-h period. Hypoglycaemic episodes, defined as glucose values<60mg/dL, were also recorded. ResultsCMT decreased consistently between 9 a.m. and 6 p.m. in 10 patients (from 374±82μm to 337±72μm; P=0.01) and increased or remained steady in 12 others (from 383±136μm to 390±149μm; P=0.58), with a significant difference in CMT absolute change between the two groups (P<0.001). In the study population as a whole, the lower the mean diurnal blood glucose, the smaller the decrease in CMT during the day (P=0.027). Also, eight (67%) of the 12 patients with a flat CMT profile experienced a diurnal hypoglycaemic event whereas none of those with a CMT decrease had hypoglycaemia (P=0.002). ConclusionHypoglycaemic events may explain the lack of diurnal CMT decrease in diabetic patients with DME. However, further studies need to be conducted to evaluate whether having no diurnal CMT decrease is associated with a poorer visual prognosis and whether it can be modified by better glucose control.