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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Diurnal and circadian rhythms are prominent in nearly all bodily functions. Chronic disruptions in normal sleep wake and social schedules can lead to serious health problems such as those seen in shift worker's syndrome. Moreover, genetic disruptions in normal circadian gene functions have recently been linked to a variety of psychiatric conditions including depression, bipolar disorder, seasonal affective disorder and alcoholism. Recent studies are beginning to determine how these circadian genes and rhythms are involved in the development of drug addiction. Several of these studies suggest an important role for these genes in limbic regions of the brain, outside of the central circadian pacemaker in the suprachiasmatic nucleus (SCN). This review summarizes some of the basic research into the importance of circadian genes in drug addiction.
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PMID:A role for the circadian genes in drug addiction. 1864 96

The purpose of this study was to investigate cortisol levels as a function of the hypothalamic-pituitary-adrenal axis (HPA) in relation to alexithymia in patients with somatoform disorders (SFD). Diurnal salivary cortisol was sampled in 32 patients with SFD who also underwent a psychiatric examination and filled in questionnaires (Toronto Alexithymia Scale, TAS scale; Screening for Somatoform Symptoms, SOMS scale; Hamilton Depression Scale, HAMD). The mean TAS total score in the sample was 55.6+/-9.6, 32% of patients being classified as alexithymic on the basis of their TAS scores. Depression scores were moderate (HAMD=13.2, Beck Depression Inventory, BDI=16.5). The patients' alexithymia scores (TAS scale "Difficulty identifying feelings") correlated significantly positively with their somatization scale scores (Symptom Checklist-90 Revised, SCL-90-R); r=0.3438 (P<0.05) and their scores on the Global Severity Index (GSI) on the SCL-90-R; r=0.781 (P<0.01). Regression analysis was performed with cortisol variables as the dependent variables. Cortisol levels [measured by the area under the curve-ground (AUC-G), area under the curve-increase (AUC-I) and morning cortisol (MCS)] were best predicted in a multiple linear regression model by lower depressive scores (HAMD) and more psychopathological symptoms (SCL-90-R). No significant correlations were found between the patients' alexithymia scores (TAS) and cortisol levels. The healthy control group (n=25) demonstrated significantly higher cortisol levels than did the patients with SFD; in both tests P<0.001 for AUC-G and AUC-I. However, the two groups did not differ in terms of their mean morning cortisol levels (P>0.05). The results suggest that pre-existing hypocortisolism might possibly be associated with SFD.
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PMID:The relationship between alexithymia and salivary cortisol levels in somatoform disorders. 1875 8

Photosynthesis and transpiration rates of wheat leaves (Triticum aestivum L.) were measured at 30 min intervals under Mediterranean field conditions, using Photosynthesis Monitor system (PM-48M). The dynamics of net photosynthetic rate (P(N)), transpiration rate (E(T)), water use efficiency (WUE), light use efficiency (LUE), stomatal conductance (g(s)), photosynthetically active radiation (PAR), air temperature (T), relative humidity (RH), and atmospheric CO2 concentration (Catm) were quantified at five rainfed wheat sites with the same stages of development (midflowering) along south-to-north and east-to-west transects for eight days in April. Diurnal P(N) (3.6 to 6.6 micromol m(-2) s(-1)), PAR (392 to 564 micromol m2 sec(-1)), LUE (0.006 to 0.015) and WUE (0.0001 to 0.011) did not vary significantly across all five wheat sites (p > 0.05). P(N) and E(T) were strongly coupled and highly correlated with PAR (p < 0.001). Best multiple linear regression (MLR) models accounted for 92% of variations in P(N) as a function of PAR and E(T), and 90% in E(T) as a function of PAR and RH (p < 0.001). P(N) exhibited a peak at mid-morning, and a photosynthetic midday depression under the limiting effects of high evaporative demand. Diurnal variations in WUE and LUE showed a bimodal behavior with the maximum values in early morning and late afternoon. As the impacts of global climate change become increasingly felt, continuous measurements of climate-crop-soil-managementinteractions under natural conditions play a pivotal role not only in exploring changes in ecophysiological properties of strategic crops for food security such as wheat but also in devising preventive and mitigative management practices to ensure sustained agricultural productivity.
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PMID:Diurnal photosynthesis, water use efficiency and light use efficiency of wheat under Mediterranean field conditions. 1897 99

Diurnal variation of depressive symptoms appears to be part of the core of depression. Yet, longitudinal investigation of an individual's pattern, regularity, relation to clinical state, and clinical improvement reveals little homogeneity. Morning lows, afternoon slump, evening worsening-all can occur during a single depressive episode. Mood variability, or the propensity to produce mood swings, appears to be the characteristic that most predicts capacity to respond to treatment. Laboratory studies have revealed that mood, like physiological variables such as core body temperature, is regulated by a circadian clock interacting with the sleep homeostat. Many depressed patients, particularly bipolar patients, show delayed sleep phase (late chronotype). Even small shifts in the timing and duration of sleep affect mood state (sleep deprivation and sleep phase advance have an antidepressant effect). The implications for treatment are to stabilize mood state by enhancing synchronization of the sleep-wake cycle with the biological clock (eg, with light therapy).
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PMID:Diurnal variation of depressive symptoms. 1897 47

Diurnal and seasonal changes in gas exchange and chlorophyll fluorescence of the uppermost-canopy leaves of four evergreen dipterocarp species were measured on clear days. The trees, that were growing in a plantation stand in southern Yunnan, China, had canopy heights ranging from 17 to 22 m. In the rainy season, Dipterocarpus retusus Bl. had higher photosynthetic capacity (A(max)) than Hopea hainanensis Merr. et Chun, Parashorea chinensis Wang Hsie and Vatica xishuangbannaensis G.D. Tao et J.H. Zhang (17.7 versus 13.9, 11.8 and 7.7 micromol m(-2) s(-1), respectively). In the dry season, A(max) in all species decreased by 52-64%, apparent quantum yield and dark respiration rate decreased in three species, and light saturation point decreased in two species. During the diurnal courses, all species exhibited sustained photosynthetic depression from midmorning onward in both seasons. The trees were able to regulate light energy allocation dynamically between photochemistry and heat dissipation during the day, with reduced actual photochemistry and increased heat dissipation in the dry season. Photorespiration played an important role in photoprotection in all species in both seasons, as indicated by a continuous increase in photorespiration rate in the morning toward midday and a high proportion of electron flow (about 30-65% of total electron flow) allocated to oxygenation for most of the day. None of the species suffered irreversible photoinhibition, even in the dry season. The sustained photosynthetic depression in the uppermost-canopy leaves of these species could be a protective response to prevent excessive water loss and consequent catastrophic leaf hydraulic dysfunction.
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PMID:Sustained diurnal photosynthetic depression in uppermost-canopy leaves of four dipterocarp species in the rainy and dry seasons: does photorespiration play a role in photoprotection? 1920 47

The discovery of two novel avian neurosteroids in the quail brain, 7alpha- and 7beta-hydroxypregnenolone is described. Intracerebroventricular administration of 7alpha-hydroxypregnenolone, but not 7beta-hydroxypregnenolone was found to stimulate locomotor activity of male quail when spontaneous nocturnal activity is low. Diurnal changes in locomotor activity in male quail were found to be correlated with a diurnal change in the concentration of diencephalic 7alpha-hydroxypregnenolone. This correlation was a not seen in female quail which have a lower amplitude diurnal rhythm of locomotor activity and lower daytime concentrations of diencephalic 7alpha-hydroxypregnenolone. Treatment of male quail with melatonin was found to depress the synthesis of 7alpha-hydroxypregnenolone in the diencephalon. This is a previously undescribed role for melatonin in the regulation of neurosteroid synthesis in the brain of any vertebrate. We therefore deduced in male quail, that the nocturnal depression in locomotory activity is a consequence of a depression in diencephalic 7alpha-hydroxypregnenolone resulting from the inhibitory action of the nocturnal increase in melatonin. This observation may be of widespread significance for the molecular control of rhythmic locomotor activity in all vertebrates.
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PMID:Discovery of a novel avian neurosteroid, 7alpha-hydroxypregnenolone, and its role in the regulation of the diurnal rhythm of locomotor activity in Japanese quail. 1936 55

Diurnal courses of photosynthetic gas exchange parameters, chlorophyll a fluorescence characteristics and the de-epoxidation state of the xanthophyll cycle pigments (DEPS) were measured during the gradual acclimation of 4-year-old Norway spruce seedlings to different photosynthetic photon flux density (PPFD) and air temperature (T(air)) regimes, simulating cloudy days with moderate T(air) (LI, maximum PPFD 300 micromol m(-2)s(-1), T(air) range 15-25 degrees C), sunny days with moderate T(air) (HI, maximum PPFD 1000 micromol m(-2)s(-1), T(air) range 15-25 degrees C) and hot sunny days (HI-HT, maximum PPFD 1000 micromol m(-2)s(-1), T(air) range 20-35 degrees C). The plants were acclimated inside a growth chamber and each acclimation regime lasted for 13d. Acclimation to HI conditions led to a strong depression of the net CO(2) assimilation rates (A(N)), particularly during noon and afternoon periods. Exposure to the HI-HT regime led to a further decrease of A(N) even during the morning period. Insufficient stomatal conductance was found to be the main reason for depressed A(N) under HI and HI-HT conditions. Only slight changes of the maximum photosystem II (PSII) photochemical efficiency (F(V)/F(M)), in the range of 0.78-0.82, supported the resistance of the Norway spruce photosynthetic apparatus against PSII photoinhibition during acclimation to both HI and HI-HT conditions. The HI plants showed increased content of xanthophyll cycle pigments (VAZ) and enhanced efficiency of thermal energy dissipation within PSII (D) that closely correlated with the increased DEPS. In contrast, acclimation to the HI-HT regime resulted in a slight reduction of VAZ content and significantly diminished D and DEPS values during the entire day in comparison with HI plants. These results indicate a minor role of the xanthophyll cycle-mediated thermal dissipation in PSII photoprotection under elevated temperatures. The different contributions of the thermal dissipation and non-assimilatory electron transport pathways in PSII photoprotection during acclimation of the Norway spruce photosynthetic apparatus to excess irradiance and heat stresses are discussed.
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PMID:Acclimation of Norway spruce photosynthetic apparatus to the combined effect of high irradiance and temperature. 2006 Jan 96

Anxiety and depression during pregnancy increase the risk for an adverse pregnancy outcome and neurodevelopmental problems in the child. The aim of this study was to investigate anxiety and depression in women with a medical disorder of pregnancy compared with control antenatal women, and any association with saliva cortisol. One hundred and twenty pregnant women (60 with a known medical disorder and 60 without, mean gestation 32 weeks) completed five self-rating questionnaires (Spielberger State and Trait Anxiety, Edinburgh Postnatal Depression Scale (EPDS), the Adult Wellbeing Scale and a Life Events Questionnaire). Diurnal saliva samples were obtained from 39 women with a medical disorder and 50 controls for cortisol analysis. The medical disorders group were significantly more anxious and depressed than the controls (mean (SD)) state anxiety 40.0 (11.5) vs. 31.6 (8.8), p = 0.00; trait anxiety 39.4 (9.5) vs. 35.2 (9.2), p = 0.02; adult wellbeing 15.9 (7.5) vs. 12.3 (7.5) p = 0.01; and EPDS 9.6 (5.4) vs. 5.9 (4.8), p = 0.00). There was no difference in the life events scores between the groups. The subgroup of women suffering from hyperemesis gravidarum had particularly high EPDS scores, (16.2 (3), n = 5, p = 0.00) compared with controls. There were no significant differences in the cortisol levels between the groups. Some women with a medical disorder during pregnancy showed considerably elevated levels of anxiety and depression. Health professionals need to be aware that these women need extra psychological support.
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PMID:Anxiety, depression and saliva cortisol in women with a medical disorder during pregnancy. 2010 21

The statement that circadian rhythmicity is an important component of mood regulation as well as a drive of mood disorders is supported by a growing body of evidence. Diurnal rhythms of the positive and negative components of mood as well as of the level of arousal depend on the circadian phase, the homeostatic sleep regulatory mechanisms and the harmonic interaction of the circadian and homeostatic processes. The chronopathological symptoms which are typical in depression and explain the blunted mood of depressive patients are of the phase-advance and phase-delay type characterized by a misalignment between the circadian rhythms and the sleep-wake schedules, best described by the phase-angle alterations. The abnormal phase angle between circadian rhythms and the timing of the sleep period could emerge from an interaction of the chronotypes and other constitutional factors with adverse environmental effects (inadequate zeitgebers) leading to a disharmony between the diurnal components of mood regulation and consequent extreme mood states. The aim of the chronotherapies of depression and of other affective disorders is that of resynchronizing the circadian rhythms or in other words to reconstitute the harmony between these subsystems. Pharmacological approaches, lifestyle changes and specific chronotherapeutic interventions might help to achieve this goal.
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PMID:[Mood, mood fluctuations and depression: role of the circadian rhythms]. 2030 3

To study the responses of growth and daily changes of photosynthesis in leaves of Pinus armandi to elevated O3, elevated CO2 and elevated O3 + CO2 in urban area, experiment was conducted in Shenyang Arboretum located at the center of the city. Five-year-old trees grown in open-top chambers (OTC) were exposed to control, elevated O3 and elevated O3 + elevated CO2 for a growing season, and the growth (fresh weight, dry weight, leaf length, axial shoot, lateral shoot), daily changes and diurnal assimilation amounts of Pinus armandi leaves were measured. The results showed that (1) the increments of fresh weight and dry weight in 70 days were reduced 45.8% and 38.9% by elevated O3 compared to the control. After 90 days, leaf length decreased 15.3%, but there were no significant difference detected in axial shoot and lateral shoot compared to the control. Diurnal assimilation amounts were decreased in elevated O3 treatment, and after 30 days exposure, net photosynthesis rate (P(n)) of leaves was decreased significantly compared to the control. Under O3 exposure, the diurnal pattern of net photosynthetic rate curve was two peaks, and a midday depression at noon was lower than control. (2) Under elevated CO2 exposure, the increments of fresh weight and dry weight in 70 days were increased 41.7% and 22.2%, but leaf length, axial shoot and lateral shoot after 90 days were not changed compared to control. Diurnal assimilation amounts were increased after elevated CO2 exposure in total, and in 30 and 60 days, net photosynthesis rates (P(n)) of leaves were higher than that of control mostly. From diurnal variation of P(n), the diurnal pattern of net photosynthetic rate curves of Pinus armandi leaf was changed from two-peaks to one-peak curue after 90 days elevated CO2 exposure, that means the midday depression was relieved by high CO2.(3) When trees were exposed to both elevated O2 and elevated CO2, the increments of fresh weight and dry weight in 70 days were all decreased compared to the control, which indicates that season-long exposure to elevated O3 had a greater effect on Pinus armandi leaves than elevated CO2, but dry weight was significantly higher than the only elevated O3 treatment, that means the O3-induced negative effect to growth of leaves can be ameliorated by elevated CO2. There were also no effects on leaf length, axial shoot and lateral shoot after 90 days exposure. When elevated O3 and CO2 were combined, net photosynthesis rate (P(n)) of leaves was lower than that of control mostly. Diurnal assimilation amounts were significantly lower than control but higher than only elevated O3 treatment, which indicated that high CO2 can largely relieve the damage of high O3 to photosynthesis of Pinus armandi leaves. The diurnal pattern of net photosynthetic rate curves of Pinus armandi leaf were also two-peak curves.
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PMID:[Effects of elevated CO2 or/and O3 on growth and daily changes of photosynthesis in leaves of Pinus armandi]. 2032 13


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