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Search Results: 1 - 10 of 818 matches for " diurnal rhythm "
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Diurnal Rhythm of Antioxidant Biomarkers in Equines  [PDF]
Erika Korinfsky Wanderley, Hélio Cordeiro Manso-Filho, Helena Emília Costa Cordeiro Manso, Stephania Katurtsch Mendes Melo, José Mário Gir?o Abreu, Juliana Andressa D’Araújo
Open Journal of Veterinary Medicine (OJVM) , 2013, DOI: 10.4236/ojvm.2013.31009

The aim of the present study was to test the hypothesis that glutathione peroxidase, uric acid, and a number of hematological biomarkers do not vary in adult mares, over a 24-hour period. Seven adult (age 10 ± 6 yrs; weight 370 ± 30 kg) Arabian Purebred mares were used. Blood samples were collected every two hours, except during the period after-meals, when samples were collected every 30 minutes, totaling four samples in two hours. These samples were used to analyze glutathione peroxidase (GPx), uric acid (UA), glucose (GLU), total plasma protein (TPP), red blood cells (RBC), hemoglobin (HB), hematocrit (HT), red cell distribution width (RDW), white blood cells (WBC) and lymphocytes (LYM). One-way repeated measures analysis of variance (ANOVA) was used to determine significant differences. Tukey’s test was used for multiple comparisons between the averages. Ρ values < 0.05 were considered statistically significant. Antioxidant biomarkers GPx and UA, as well as hematological biomarkers TPP, RBC, HB and HT exhibited a diurnal rhythm that was not affected by food ingestion, while RDW-SD, RDW-CV, WBC and LYM did not present a statistically significant change in the same period.

Diurnal Variation of Nuclear Receptors in Mice with or without Fasting  [PDF]
Atsushi Kawase, Tetsuya Ohgami, Iho Yoshida, Yu Tsunokuni, Masahiro Iwaki
Pharmacology & Pharmacy (PP) , 2013, DOI: 10.4236/pp.2013.42033

Nuclear receptors such as pregnane X receptor (PXR) and constitutive androstane receptor (CAR) regulate the transcription of transporter and cytochrome P450 (CYP). The diurnal variation was observed in some transporters regulated by nuclear receptors. We investigated whether diurnal variation in PXR and CAR exists in mice. We also examined the effect of food intake on the diurnal rhythm of hepatic PXR and CAR using fed and fasted mice. In liver and small intestine of fed mice, the mRNA levels of PXR and CAR were unchanged between 7:00 AM and 7:00 PM. In contrast to fed mice, fasting mice partly exhibited the diurnal variation in PXR, not in CAR. The mRNA levels of PXR at 7:00 AM were significantly higher than that those at 7:00 PM in liver of fasting mice. These results indicated the different effects of fasting in mice on diurnal variation of PXR in each tissue.

Photosynthetic characteristics of the freshwater red alga Batrachospermum delicatulum (Skuja) Necchi & Entwisle
Necchi Júnior, Orlando;Alves, Abner H.S.;
Acta Botanica Brasilica , 2005, DOI: 10.1590/S0102-33062005000100012
Abstract: six populations of the freshwater red alga batrachospermum delicatulum (skuja) necchi & entwisle, including gametophyte and 'chantransia' stage, were analysed in culture and natural conditions applying chlorophyll fluorescence and oxygen evolution. parameters derived from the photosynthesis-irradiance curves indicated adaptation to low irradiance for all populations, which was characterized by photoinhibition, low values of ik and ic and high values of a. data from both techniques revealed significant differences among populations and phases for most photosynthetic parameters. similarly, photosynthesis responded differently to variations in temperature in each population with similar rates under a wide range of temperature. no consistent pattern was found when the same population or phase was tested, suggesting high capacity to adjust the photosynthetic apparatus to distinct conditions of irradiance and temperature. ph experiments showed a decreasing trend towards higher ph or higher rates at ph 6.5, suggesting, respectively, higher affinity to inorganic carbon as co2 or indistinct use of bicarbonate and co2. the diurnal pattern of photosynthesis essentially agree with that for seaweeds and freshwater red algae, consisting of two peaks: a first (generally higher) during the morning and a second (typically lower) in the afternoon. photosynthetic characteristics of b. delicatulum (skuja) necchi & entwisleexhibited a wide range of responses to irradiance, temperature and ph/inorganic carbon, reflecting its wide tolerance to these variables, which probably contributes to its wide spatial and temporal distribution.
Varia??es diurnas da atividade in vivo da redutase do nitrato em abacaxizeiro (Ananas comosus (L.) Merr. - Bromeliaceae)
Brazilian Journal of Botany , 2001, DOI: 10.1590/S0100-84042001000300008
Abstract: determination of nitrate reductase activity (nr) was based on the in vivo assay method, which was standardised for leaves and roots of pineapple cultivated in vitro. the highest activity was obtained when tissues were incubated in 0.1 m phosphate buffer, 100 mm kno3 and 3% of n-propanol. the optimal ph ranged from 6.5 to 7.5. the incubation period was 60 min at 30 °c. this standardisation was important for the diurnal rhythm analysis of nitrate reductase activity in pineapple because the conditions of in vivo assay for this enzyme vary significantly among different plant species. the diurnal rhythm analysis showed that in leaves, the highest activity occurred during the day. the nr activity in the roots during the dark period was similar to that observed during the light period. the nr activity in roots was always higher than in leaves, indicating that roots are an important site for nitrate reduction when pineapple is cultivated in vitro. the nitrate accumulation in leaves during the diurnal cycle showed that it is present in higher concentrations in the light period. therefore a positive correlation between nitrate concentration and nr activity could be established. in roots, however, the highest nitrate concentrations were observed in the absence of light. in this case, it is possible that other factors, besides nitrate, contributed to a higher enzymatic activity during the light period.
Diurnal changes of blood pressure values (24 h blood pressures) in women with polycystic ovary syndrome
Barbara Grzechocińska,Anna Cyganek,Piotr Marianowski
Przegl?d Menopauzalny , 2011,
Abstract: Background: More attention is being paid lately to polycystic ovary syndrome (PCOS) not only in the aspect of fertility but also according to long-term metabolic and cardiovascular abnormalities. Observations of women with PCOS show that the occurrence of blood hypertension is more frequent after the menopause. There are few articles concerning the predictable symptoms of blood hypertension. It seems that twenty-four hour blood pressure monitoring and assessment of changes of diurnal rhythm could be useful in this group of patients.Aim of the study: The purpose of this study was to assess diurnal changes of blood pressure in women with polycystic ovary syndrome.Material and methods: 26 women with PCOS diagnosed according to Rotterdam consensus criteria and Androgen Excess Society (AES) criteria were included in our study. The mean age of the examined women was 29.5 years and the mean BMI (body mass index) was 24.7 kg/m2. The control group consisted of 12 age-matched women, without PCOS. Twenty-four hour Holter monitoring of ambulatory blood pressure was performed during normal daily activity in all patients. Halberg’s cosinor method was used to analyse daily biorhythm.Results: Results show the diurnal changes of systolic blood pressure in the preclinical phase in 30% and diastolic in 15% of PCOS women. In this group no physiological decrease of blood pressure at night time was observed.
Varia es diurnas da atividade in vivo da redutase do nitrato em abacaxizeiro (Ananas comosus (L.) Merr. - Bromeliaceae)
Brazilian Journal of Botany , 2001,
Abstract: A análise da atividade enzimática da redutase do nitrato baseou-se no método do ensaio in vivo, que foi padronizado para os tecidos foliares e radiculares do abacaxizeiro cultivado in vitro. As maiores atividades enzimáticas foram obtidas quando se empregou como meio de rea o uma solu o tamp o fosfato 0,1 M, contendo KNO3 100 mM e 3% de n-propanol, a faixa de pH ótimo foi de 6,5 a 7,5. O tempo de incuba o foi de 60 min a 30 °C. Essa padroniza o mostrou-se muito importante para a análise do ritmo diurno da redutase do nitrato em abacaxizeiro, visto que as condi es de ensaio in vivo dessa enzima variam muito entre diferentes espécies vegetais. As folhas apresentaram as maiores atividades na presen a de luz. As raízes mostraram atividade da redutase do nitrato também na ausência de luminosidade em níveis semelhantes aos observados na presen a de luz. A atividade observada nas raízes foi sempre superior à das folhas, sugerindo que as raízes têm um importante papel na redu o do nitrato nas condi es de cultivo in vitro. O acúmulo de nitrato observado durante o ciclo diurno, nas folhas, evidenciou que a presen a desse íon ocorreu em maiores níveis durante o período luminoso, estabelecendo uma correla o positiva com a atividade da redutase do nitrato. Entretanto, nas raízes, as maiores concentra es foram observadas na ausência de luz. Nesse caso, discute-se a possibilidade de outros fatores, além do nitrato, estarem contribuindo positivamente, induzindo uma elevada atividade enzimática na presen a de luz.
Temporal Patterns of Blood Lipidperoxides and Antioxidants in 7,12-dimethylbenz(a)anthracene Induced Hamster Buccal Pouch Carcinogenesis
Kannan Kavitha,Shanmugam Manoharan,Kathiresan Suresh
International Journal of Pharmacology , 2006,
Abstract: Our aim was to investigate the temporal patterns of lipid peroxidation byproducts [thiobarbituric acid reactive substances (TBARS)] and enzymatic antioxidants [superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)] in 7,12-dimethylbenz(a)anthracene (DMBA) induced hamster buccal pouch carcinogensis. The levels of thiobarbituric acid reactive substances and the activities of antioxidant enzymes were assayed at 4 h intervals throughout the 24 h period using colorimetric methods. The Cosinorwin computer software program was used to analyse the characteristics of biochemical rhythms such as acrophase, amplitude and mesor etc., Delayed acrophase was noticed for lipid peroxides and antioxidant enzymes in hamsters with oral squamous cell carcinoma as compared to control animals. Elevated and declined mesor values for TBARS and enzymatic antioxidants, respectively were observed in cancer animals. The disrupted diurnal rhythms of TBARS and antioxidants observed in the present study reflected an alteration of circadian clock function for these biochemical variables in DMBA induced oral carcinogenesis.
Repeated Exposure to Conditioned Fear Stress Increases Anxiety and Delays Sleep Recovery Following Exposure to an Acute Traumatic Stressor
Benjamin N. Greenwood,Robert S. Thompson,Mark R. Opp,Monika Fleshner
Frontiers in Psychiatry , 2014, DOI: 10.3389/fpsyt.2014.00146
Abstract: Repeated stressor exposure can sensitize physiological responses to novel stressors and facilitate the development of stress-related psychiatric disorders including anxiety. Disruptions in diurnal rhythms of sleep–wake behavior accompany stress-related psychiatric disorders and could contribute to their development. Complex stressors that include fear-eliciting stimuli can be a component of repeated stress experienced by human beings, but whether exposure to repeated fear can prime the development of anxiety and sleep disturbances is unknown. In the current study, adult male F344 rats were exposed to either control conditions or repeated contextual fear conditioning for 22 days followed by exposure to no, mild (10), or severe (100) acute uncontrollable tail shock stress. Exposure to acute stress produced anxiety-like behavior as measured by a reduction in juvenile social exploration and exaggerated shock-elicited freezing in a novel context. Prior exposure to repeated fear enhanced anxiety-like behavior as measured by shock-elicited freezing, but did not alter social exploratory behavior. The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress. Interestingly, exposure to acute stress reduced rapid eye movement (REM) and non-REM (NREM) sleep during the hours immediately following acute stress. This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep/wake behavior. Prior repeated fear extended the acute stress-induced REM and NREM sleep loss, impaired REM rebound, and prolonged the flattening of the diurnal rhythm of NREM sleep following acute stressor exposure. These data suggest that impaired recovery of sleep/wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.
Circadian rhythms of sexual activities in moths: a review
Astrid T. Groot
Frontiers in Ecology and Evolution , 2014, DOI: 10.3389/fevo.2014.00043
Abstract: The circadian rhythm of behavior has interested many researchers in the past decades, yet amazingly little is known on the evolution of natural variation in circadian rhythms of behavior. Most research has been focused on identifying the circadian clock genes that form an intricate clock network, which turns out to be more complex with every discovery. To understand the importance of circadian rhythms of behavior in speciation, genetic analyses should be conducted on intra- and interspecific allochronic differentiation of behaviors. Many moth species show specific daily activity rhythms in their sexual activities, some species being sexually active early at night, while others are sexually active late at night. This differentiation has been suggested to have arisen to minimize communication interference between closely related species, as co-occurring and closely related species with overlapping sex pheromone blends show a temporal differentiation in their daily sexual activities. However, the genetic differentiation of this allochronic separation has barely been examined in any species so far. In this review I summarize studies conducted on timing of sexual activities in moths, and which factors have been found to influence this timing, with the aim to identify the gaps and challenges, to unravel the possible contribution of allochronic differentiation of sexual activities in moth speciation.
Diurnal rhythm of reproductive behavior of cotton leafworm Spodoptera litura (Fabricius)(Lepidoptera: Noctuidae)feeding on different hosts

武承旭,杨茂发,曾昭华,姚苗苗,廖启荣,Wu Chengxu,Yang Maofa,Zeng Zhaohua,Yao Miaomiao,Liao Qirong
- , 2015, DOI: 10.13802/j.cnki.zwbhxb.2015.02.010
Abstract: 为摸清斜纹夜蛾成虫在不同寄主上的行为节律变化, 在室内分别用烟草和白菜饲养3代, 建立烟草种群和白菜种群, 比较分析了成虫的羽化、交配、产卵等行为节律。结果表明:烟草种群雌虫有2个羽化高峰期, 分别在熄灯前2 h和熄灯后1 h, 雄虫只有1个高峰期, 出现在熄灯后2 h;白菜种群雌、雄虫均有2个高峰期, 主、次高峰期分别在熄灯前后1 h内和熄灯后4~5 h。2种群均有2个交配高峰期, 烟草种群第1高峰期在熄灯后2 h, 而白菜种群在熄灯后5 h, 第2高峰期均在开灯前2 h;烟草种群和白菜种群一生的交配持续时间分别为54.78±3.09 min和60.00±2.58 min, 差异不显著;烟草种群一生交配1~3次, 而白菜种群只交配1次, 差异极显著;2种群均只有1个产卵高峰期, 烟草种群在熄灯后4 h, 白菜种群则在熄灯后5 h。表明斜纹夜蛾取食烟草和白菜2种不同寄主其成虫繁殖节律会发生较大的改变。
In order to find out the differences in the behavioral rhythm of Spodoptera litura adults on different host plants, diurnal rhythms of adult emergence, mating and ovulating between tobacco population and cabbage population were carefully researched for three generations indoors. The results showed that the diurnal rhythm of two host populations were different. Female adults of tobacco population had two emergence peaks: one appeared two hours before lights out and the other one hour after lights out; males had only one peak that appeared two hour after lights out. Both male and female adults of cabbage population had two emergence peaks: the main peak appeared one hour before and after lights out and the subordinate peak appeared between four and five hours after lights out. Mating and ovulating behaviors of both populations appeared at night. Both populations had two mating peaks: the first peak of tobacco population appeared two hours after lights out, while the cabbage population appeared five hours after lights out; the second appeared two hours before lights on. Two populations had only one ovulating peak: the tobacco population appeared four hours after lights out, while the cabbage population appeared five hours after lights out. The lifetime mating duration of the tobacco population and cabbage population were 54.78±3.09 min and 60±2.58 min, respectively, and they were not significantly different. Tobacco population mated 1-3 times, but cabbage population mated only one time. The results indicated that the reproductive diurnal rhythm of S. litura varied after they fed on tobacco and cabbage.
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