Read by QxMD icon Read

Diurnal variation

Mohamed W Osman, Francesca Leone, Mintu Nath, Asma Khalil, David R Webb, Thompson G Robinson, Hatem A Mousa
AIM: To investigate same day repeated measures and diurnal variation of arterial stiffness, cardiac output (CO), stroke volume (SV) and total peripheral resistance (TPR) during the third trimester of normal pregnancy. METHODOLOGY: Pulse wave velocity (PWV) and augmentation index (AIx) were recorded using the Arteriograph, while CO, SV and TPR were recorded using noninvasive cardiac output monitoring. The measurements were obtained in the third trimester of pregnancy from 21 healthy pregnant women at four time points (morning, afternoon, evening and midnight) over a 24-h period...
July 14, 2017: Journal of Hypertension
Luciana Ripamonti, Roberto Riva, Fabiola Maioli, Corrado Zenesini, Gaetano Procaccianti
Three thousand two hundred and ninety-eight patients admitted to our Stroke Unit with hemorrhagic, large artery atherosclerosis, cardioembolic, small-vessel occlusion, and undetermined etiology-cryptogenic strokes were included in the study. The circadian variability in onset in each stroke subgroup and the associations with various risk factors were analyzed. In each subgroup, a significant minority of patients suffered from stroke during sleep. In the ischemic group, hypercholesterolemia, paroxysmal atrial fibrillation, and previous myocardial infarction facilitated the onset during waking...
2017: Stroke Research and Treatment
Aaron D Flesch, Philip C Rosen, Peter Holm
Understanding how climatic variation affects animal populations and communities is essential for addressing threats posed by climate change, especially in systems where impacts are projected to be high. We evaluated abundance dynamics of five common species of diurnal lizards over 25 years in a Sonoran Desert transition zone where precipitation decreased and temperature increased across time, and assessed hypotheses for the influence of climatic flux on spatiotemporal variation in abundances. We repeatedly surveyed lizards in spring and summer of each year at up to 32 sites, and used hierarchical mixture models to estimate detection probabilities, abundances, and population growth rates...
July 16, 2017: Global Change Biology
Dawei Wang, Anne-Loes Opperhuizen, Jane Reznick, Nigel Turner, Yan Su, Gregory J Cooney, Andries Kalsbeek
Shiftworkers are exposed to several adverse health conditions, one being eating at night. Food consumption at an unnatural time-of-day is thought to be one of the main factors responsible for the increased risk of developing metabolic diseases, such as obesity and diabetes mellitus. The underlying mechanism is considered to include disruption of the circadian organization of physiology, leading to disruption of metabolism. When food is consumed at night, the hypothalamus, a brain region central to homeostasis, receives contradicting input from the central clock and the systemic circulation...
July 11, 2017: Brain Research
Zheng-Hong Tan, Zhi-Xiang Wu, Alice C Hughes, Douglas Schaefer, Jiye Zeng, Guo-Yu Lan, Chuang Yang, Zhong-Liang Tao, Bang-Qian Chen, Yao-Hua Tian, Liang Song, Muhammad Tahir Jatoi, Jun-Fu Zhao, Lian-Yan Yang
The ratio of intercellular to ambient CO2 concentrations (c i/c a) plays a key role in ecophysiology, micrometeorology, and global climatic change. However, systematic investigation on c i/c a variation and its determinants are rare. Here, the c i/c a was derived from measuring ecosystem fluxes in an even-aged monoculture of rubber trees (Hevea brasiliensis). We tested whether c i/c a is constant across environmental gradients and if not, which dominant factors control c i/c a variations. Evidence indicates that c i/c a is not a constant...
July 13, 2017: International Journal of Biometeorology
Maximilian Gabriel, Marieh Esmaeelpour, Farnusch Shams-Mafi, Boris Hermann, Behrooz Zabihian, Wolfgang Drexler, Susanne Binder, Siamak Ansari-Shahrezaei
PURPOSE: To test the significance of diurnal changes in choroidal, Haller's and Sattler's layer thickness in healthy subjects using spatial analysis of three-dimensional (3D) 1060-nm optical coherence tomography (OCT) scans. METHODS: Automatically generated choroidal, Haller's and Sattler's layer thickness maps were statistically analyzed for 19 healthy subjects at two time points (8 a.m. and 6 p.m.) that represent the currently proposed ChT peak and nadir. All subjects were imaged by high-speed 1060-nm OCT over a 36° × 36° field of view...
July 12, 2017: Graefe's Archive for Clinical and Experimental Ophthalmology
Caroline H Reid, Niall J Finnerty
We detail an extensive characterisation study on a previously described dual amperometric H₂O₂ biosensor consisting of H₂O₂ detection (blank) and degradation (catalase) electrodes. In vitro investigations demonstrated excellent H₂O₂ sensitivity and selectivity against the interferent, ascorbic acid. Ex vivo studies were performed to mimic physiological conditions prior to in vivo deployment. Exposure to brain tissue homogenate identified reliable sensitivity and selectivity recordings up to seven days for both blank and catalase electrodes...
July 8, 2017: Sensors
Jonathan Vergara-Amado, Andrea X Silva, Catalina Manzi, Roberto F Nespolo, Leyla Cárdenas
Marine ectotherms inhabiting intertidal and shallow subtidal environments are continuously exposed to diurnal tidal cycles and seasonal variability in temperature. These organisms have adaptive mechanisms to maintain cellular homeostasis, irrespective of thermal environmental variation. In this study, we describe the molecular responses to thermal stress in the edible sea urchin Loxechinus albus. In particular, we determined the differential expression of a set of molecular markers that have been identified as targets of stress-related responses...
August 2017: Journal of Thermal Biology
L K Sahu, Nidhi Tripathi, Ravi Yadav
This paper presents the sources and characteristics of ambient volatile organic compounds (VOCs) measured using PTR-TOF-MS instrument in a metropolitan city of India during winter to summer transition period. Mixing ratios of VOCs exhibited strong diurnal, day-to-day and episodic variations. Methanol was the most dominant species with monthly mean values of 18-22 pbbv. The emission ratios of VOCs relative to benzene calculated from nighttime data were used to estimate the relative contributions of vehicle exhaust and other sources...
July 6, 2017: Environmental Pollution
Petr Baldrian
Microbial activity in forest soils is driven by the dynamics of ecosystem processes, largely dependent on trees as the major primary producers. Diurnal variation of root activity, seasonality of photosynthate production or recalcitrance of decomposing plant biomass all affect microbial abundance, composition of their communities and activity. Due to low N content, fungi appear to be the major decomposers of complex plant biomass: litter and deadwood and to largely shape associated bacterial communities and their activity...
July 6, 2017: Current Opinion in Microbiology
Junyan Duan, Jun Tao, Yunfei Wu, Tiantao Cheng, Renjian Zhang, Yanyu Wang, Hailin Zhu, Xin Xie, Yuehui Liu, Xiang Li, Lingdong Kong, Mei Li, Qianshan He
Cloud condensation nuclei (CCN), condensation nuclei (CN) and aerosol chemical composition were measured simultaneously at an urban site of Guangzhou from July to August 2015 and in January 2016, and the seasonal variations of aerosol activated fractions (NCCN/NCN) as well as their relevant influence factors were further studied accordingly. NCN is generally higher in winter (dry season), whereas NCCN and NCCN/NCN are mostly higher in summer (wet season) instead. In particular, NCCN and NCCN/NCN are much lower at smaller supersaturation levels (SS<0...
July 4, 2017: Science of the Total Environment
Toshiyuki Iwahori, Hirotsugu Ueshima, Sayuki Torii, Yoshino Saito, Keiko Kondo, Sachiko Tanaka-Mizuno, Hisatomi Arima, Katsuyuki Miura
This corrects the article DOI: 10.1038/hr.2016.187.
July 2017: Hypertension Research: Official Journal of the Japanese Society of Hypertension
Yiming Zhang, Dan Wan, Xihong Zhou, Ciming Long, Xin Wu, Lan Li, Liuqin He, Pan Huang, Shuai Chen, Bie Tan, Yulong Yin
Diurnal variations in serum iron levels have been well documented in clinical studies, and serum iron is an important diagnostic index for iron-deficiency anemia. However, the underlying mechanism of dynamic iron regulation in response to the circadian rhythm is still unclear. In this study, we investigated daily variations in iron status in the plasma and liver of pigs. The transcripts encoding key factors involved in iron uptake and homeostasis were evaluated. The results showed that iron levels in the plasma and liver exhibited diurnal rhythms...
July 1, 2017: Biochemical and Biophysical Research Communications
Precious L Hajison, Bonex W Mwakikunga, Don P Mathanga, Shingairai A Feresu
BACKGROUND: Malaria is seasonal and this may influence the number of children being treated as outpatients in hospitals. The objective of this study was to investigate the degree of seasonality in malaria in lakeshore and highland areas of Zomba district Malawi, and influence of climatic factors on incidence of malaria. METHODS: Secondary data on malaria surveillance numbers and dates of treatment of children <5 years of age (n = 374,246) were extracted from the Zomba health information system for the period 2012-2016, while data on climatic variables from 2012 to 2015 were obtained from meteorological department...
July 3, 2017: Malaria Journal
Luhuizi Qi, Jingchun Ma, Jie Song, Shangge Li, Xiaoru Cui, Xiaojing Peng, Weiliang Wang, Zongming Ren, Mei Han, Ying Zhang
In order to illustrate heavy metal ecotoxicology associated with interactions between chemicals and biological systems, we investigated physiological changes (metabolism and behavior response) of zebra fish (Danio rerio) under 48 h Cadmium chloride (CdCl2) exposure using online monitoring technique. The concentrations of CdCl2 were designed as 4.26, 42.6 and 85.2 mg/L, which were 0.1, 1.0, and 2.0 based on toxic unit (TU), respectively. The metabolism was assessed using the oxygen consumption (OC), and the behavior response was analyzed in behavior strength (BS)...
June 13, 2017: Chemosphere
Rui Zhang, Moritz D Brandt, Wiebke Schrempf, Christian Beste, Ann-Kathrin Stock
The circadian variation of sensory and motor symptoms with increasing severity in the evening and at night is a key diagnostic feature/symptom of the restless legs syndrome (RLS). Even though many neurological diseases have shown a strong nexus between motor and cognitive symptoms, it has remained unclear whether cognitive performance of RLS patients declines in the evening and which neurophysiological mechanisms are affected by the circadian variation. In the current study, we examined daytime effects (morning vs...
2017: NeuroImage: Clinical
Maximilian J Schloss, Michael Hilby, Katrin Nitz, Raquel Guillamat Prats, Bartolo Ferraro, Giovanna Leoni, Oliver Soehnlein, Thorsten Kessler, Wenyan He, Bruno Luckow, Michael Horckmans, Christian Weber, Johan Duchene, Sabine Steffens
OBJECTIVE: Circadian regulation of neutrophil homeostasis affects myocardial infarction (MI) healing. It is unknown whether diurnal variations of monocyte counts exist in the heart and whether this affects their cardiac infiltration in response to MI. APPROACH AND RESULTS: Murine blood and organs were harvested at distinct times of day and analyzed by flow cytometry. Ly6C(high) monocyte surface expression levels of chemokine receptors (CCR) were ≈2-fold higher at the beginning of the active phase, Zeitgeber Time (ZT) 13 compared with ZT5...
June 29, 2017: Arteriosclerosis, Thrombosis, and Vascular Biology
Hoon Young Choi, Chan Joo Lee, Jung Eun Lee, Hyun Su Yang, Ha Yan Kim, Hyeong Cheon Park, Hyeon Chang Kim, Hyuk-Jae Chang, Sung-Ha Park, Beom Seok Kim
Diurnal variations in blood pressure (BP) loss are closely associated with target organ damage and cardiovascular events. The quantity of coronary artery calcification (CAC) correlates with the atherosclerotic plaque burden, and an increased quantity indicates a substantially increased risk of cardiovascular events. This study investigated the nighttime diurnal variation in BP loss associated with CAC in patients with chronic kidney disease (CKD).Of the 1958 participants, we enrolled 722 participants with CKD without a history of acute coronary syndrome or symptomatic coronary artery disease...
June 2017: Medicine (Baltimore)
Qingyu Guan, Ao Cai, Feifei Wang, Liqin Yang, Chuanqi Xu, Zeyu Liu
To investigate the spatial and temporal behaviors of particulate matter in Lanzhou, Jinchang and Jiayuguan during 2014, the hourly concentrations of PM2.5 and PM10 were collected from the Ministry of Environmental Protection (MEP) in this study. The analysis indicated that the mean annual PM10 (PM2.5) concentrations during 2014 were 115 ± 52 μg/m(3) (57 ± 28 μg/m(3)), 104 ± 75 μg/m(3) (38 ± 22 μg/m(3)) and 114 ± 72 μg/m(3) (32 ± 17 μg/m(3)) in Lanzhou, Jinchang and Jiayuguan, respectively, all of which exceeded the Chinese national ambient air quality II standards for PM...
June 23, 2017: Environmental Pollution
Marion Fournier, Fabienne d'Arripe-Longueville, Carole Rovere, Christopher S Easthope, Lars Schwabe, Jonathan El Methni, Rémi Radel
OBJECTIVE: Given the impact of individuals' habits on health, it is important to study how behaviors can become habitual. Cortisol has been well documented to have a role in habit formation. This study aimed to elucidate the influence of the circadian rhythm of cortisol on habit formation in a real-life setting. METHOD: Forty-eight students were followed for 90 days during which they attempted to adopt a health behavior (psoas iliac stretch). They were randomly assigned to perform the stretch either upon waking in the morning, when cortisol concentrations are high, or before evening bedtime, when cortisol levels approach the nadir...
June 26, 2017: Health Psychology: Official Journal of the Division of Health Psychology, American Psychological Association
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"