A Comparative Study of Regional Homogeneity of Resting-State fMRI Between the Early-Onset and Late-Onset Recurrent Depression in Adults.

Background: Neurobiological mechanisms underlying the recurrence of major depressive disorder (MDD) at different ages are unclear, and this study used the regional homogeneity (ReHo) index to compare whether there are differences between early onset recurrent depression (EORD) and late onset recurrent depression (LORD). Methods: Eighteen EORD patients, 18 LORD patients, 18 young healthy controls (HCs), and 18 older HCs were included in the rs-fMRI scans. ReHo observational metrics were used for image analysis and further correlation of differential brain regions with clinical symptoms was analyzed. Results: ANOVA analysis revealed significant differences between the four groups in ReHo values in the prefrontal, parietal, temporal lobes, and insula. Compared with EORD, the LORD had higher ReHo in the right fusiform gyrus/right middle temporal gyrus, left middle temporal gyrus/left angular gyrus, and right middle temporal gyrus/right angular gyrus, and lower ReHo in the right inferior frontal gyrus/right insula and left superior temporal gyrus/left insula. Compared with young HCs, the EORD had higher ReHo in the right inferior frontal gyrus/right insula, left superior temporal gyrus/left insula, and left rolandic operculum gyrus/left superior temporal gyrus, and lower ReHo in the left inferior parietal lobule, right inferior parietal lobule, and left middle temporal gyrus/left angular gyrus. Compared with old HCs, the LORD had higher ReHo in the right fusiform gyrus/right middle temporal gyrus, right middle temporal gyrus/right angular gyrus, and left rolandic operculum gyrus/left superior temporal gyrus, and lower ReHo in the right inferior frontal gyrus/right insula. ReHo in the right inferior frontal gyrus/right insula of patients with LORD was negatively correlated with the severity of 17-item Hamilton Rating Scale for Depression (HAMD-17) scores (r = -0.5778, p = 0.0120). Conclusion: Adult EORD and LORD patients of different ages have abnormal neuronal functional activity in some brain regions, with differences closely related to the default mode network (DMN) and the salience network (SN), and patients of each age group exhibit ReHo abnormalities relative to matched HCs. Clinical Trial Registration: [http://www.chictr.org.cn/], [ChiCTR1800014277].

[Effects of water vapor source and local environmental factors on the hydrogen and oxygen isotopic compositions of precipitation in Huitong, Hunan Province, China].

Deuterium (D) and oxygen-18 (18O) are common environmental tracers in water. Understanding the isotopic compositions of precipitation is necessary for further studies on local and global water cycling processes. To reveal the mechanism of isotopic compositions of precipitation in subtropical monsoon region in response to environmental changes, we collected 49 precipitation samples and recorded related environmental factors from May 2017 to August 2019 in Huitong field station of Chinese Academy of Sciences in Hunan Province. We analyzed the temporal variations in D and 18O values in precipitation and analyzed the influence of water vapor source and local environmental factor on stable isotopic compositions of precipitation. The local meteoric water line was established as δD=(7.45±0.17)δ18O+(10.10±1.25) (R2=0.93, P<0.01), the slope of which was slightly lower than China's meteoric water line and the global meteoric line. The D and 18O values of precipitation samples were closely coupled with local meteorological conditions and dominant moisture sources. The 18O and D contents were depleted during summer monsoon season but enriched during winter monsoon season. During the summer monsoon and post-monsoon seasons, precipitation in this area came mainly from the Bay of Bengal, the South China Sea, and the West Pacific at three different types of air pressure, which lead to the similarity of the D-excess value of the precipitation to global average. The lower intercept of meteoric water line and the higher D-excess value for precipitation during the winter monsoon season resulted from moisture from remote westerly air masses, degenerated tropical marine air masses from the Bay of Bengal, and inland moisture in the pre-monsoon period, which were also affected by local environmental factors.

[Characteristics of hydrogen and oxygen isotopes in precipitation and moisture sources in Gaoyou, Jiangsu Province, China]. / æ±Ÿè‹é«˜é‚®å¤§æ°”é™æ°´æ°¢æ°§åŒä½ç´ ç‰¹å¾åŠæ°´æ±½æ¥æº.

It is necessary to examine the characteristics of hydrological cycle in Gaoyou area of Jiang-su Province in response to climate change and flood disasters. In this study, 121 atmospheric rain samples were collected and environmental factors were recorded from July 2015 to October 2017. We analyzed the hydrogen and oxygen stable isotopic composition of rain and identify moisture sources in this area. Results showed that the hydrogen and oxygen isotopic composition of rain had an seasonal variation, which was positive in the winter but negative in the summer. D-excess value was higher in winter than that in summer. On the annual scale, significantly negative relationships between δD (δ18O) and temperature and between δD (δ18O) and precipitation indicated the "anti-temperature effect" and "precipitation amount effect", respectively. On the seasonal scale, there was no obvious "temperature effect" but "precipitation amount effect" in autumn and winter. Results from the HYSPLIT model showed that the precipitation in this area came mainly from ocean evaporation that was influenced by the Chinese South Sea, Indian Ocean and Pacific Ocean. Precipi-tation in other seasons mainly came from the water vapor mixture from the Eurasian continent, Atlantic Ocean, Arctic Ocean, as well as local evaporation. The seasonal pattern of δD and δ18O values in precipitation was mainly influenced by monsoon activity and El Niño-Southern Oscillation (ENSO). In addition, the precipitation isotopes clearly indicated the shift in climates from El Niño to La Niña.

[Deuterium isotope characteristics of precipitation infiltrated in the West Ordos Desert of Inner Mongolia, China]. / å† è’™å¤è¥¿é„‚å°”å¤šæ–¯è’æ¼ åŒºé™æ°´å ¥æ¸—æ°˜åŒä½ç´ ç‰¹å¾.

Understanding the soil-profile temporal and spatial distribution of rainwater in arid and semiarid regions provides a scientific basis for the restoration and maintenance of degraded desert ecosystems in the West Ordos Desert of Inner Mongolia, China. In this study, the deuterium isotope (δD) value of rainwater, soil water, and groundwater were examined in the West Ordos Desert. The contribution of precipitation to soil water in each layer of the soil profile was calculated with two-end linear mixed model. In addition, the temporal and spatial distribution of δD of soil water in the soil profile was analyzed under different-intensity precipitation. The results showed that small rainfall events (0-10 mm) affected the soil moisture and the δD value of soil water in surface soil (0-10 cm). About 30.3% to 87.9% of rainwater was kept in surface soil for nine days following the rainfall event. Medium rainfall events (10-20 mm) influenced the soil moisture and the δD value of soil water at soil depth of 0-40 cm. About 28.2% to 80.8% of rainwater was kept in soil layer of 0-40 cm for nine days following the medium rainfall event. Large (20-30 mm) and extremely large (＞30 mm) rainfall events considerably influenced the soil moisture and δD value of soil water in each of the soil layers, except for the 100-150 cm layer. The δD value of soil water was between those δD values of rainwater and groundwater, which suggested that precipitation and groundwater were the sources of soil water in the West Ordos Desert. Under the same intensity rainfall, the δD value of surface soil water (0-10 cm) was directly affected by δD of rainwater. With increasing soil depth, the variation of soil water δD decreased, and the soil water of 100-150 cm kept stable. With increasing intensity of precipitation, the influence of precipitation on soil water δD lasted for a longer duration and occurred at a deeper soil depth.