[Spatial Distribution and Influential Factors of Nutrients in Rivers of a Typical Mountainous City: A Case Study of the Qingshuixi River in Chongqing].

Surface water pollution seriously restricts the development of the city and results in the citizens yearning for a better life. Mountainous cities have their own characteristics in surface water environment and pollution compared with those of plain cities due to their unique topography. In August and October 2019, surface water and sediments were collected in a typical river (Qingshuixi River) in the main urban area of Chongqing. These samples were analyzed for nutrients such as carbon, nitrogen, and phosphorus as well as other basic physicochemical indicators. The results showed that the surface water of the Qingshuixi River was inferior to Category V at present, and it was also at a serious pollution level according to the comprehensive pollution index evaluation system. Among all the water quality indices, NH4+ and TP showed the most serious pollution. The tributaries of the Qingshuixi River exhibited higher surface water quality than that of the main stream, and the water quality during the rainfall season was better than that during the non-rainy season. Pollution sources, tailwater/tributary inflow, and river self-purification capacity determined the spatial distribution of nutrients in the surface water of the mainstream of the Qingshuixi River. Point sources such as the direct discharge of source sewage and pollution overflow in the middle and lower reaches were the most important sources of surface water pollution in the mainstream of the Qingshuixi River. Non-point source pollution had a limited impact on water quality. The "sink" or "source" role transformation of river sediments would occur under different water volume conditions in the river, reflecting the complexity of endogenous pollution. Surface water quality of the main stream showed a gradual improvement tendency along the downstream due to the dilution of the tail water/tributary inflow and the increased self-purification capability of the surface water in the mountainous rivers due to the increased DO content. To summarize, this study suggests that the water environment of the Qingshuixi River should be improved in comprehensive ways, which might be reducing the input of point source pollution by the deployment of the municipal pipe network in key areas, upgrading the sewage treatment plants to decrease pollutant concentrations or fluxes or channel dredging at the reaches with low DO content, etc.

Blockade of Nogo-A/Nogo-66 receptor 1 (NgR1) Inhibits Autophagic Activation and Prevents Secondary Neuronal Damage in the Thalamus after Focal Cerebral Infarction in Hypertensive Rats.

Focal cerebral infarction leads to autophagic activation, which contributes to secondary neuronal damage in the ipsilateral thalamus. Although Nogo-A deactivation enhances neuronal plasticity, its role in autophagic activation in the thalamus after ischemic stroke remains unclear. This study aimed to investigate the potential roles of Nogo-A/Nogo-66 receptor 1 (NgR1) in autophagic activation in the ipsilateral thalamus after cerebral infarction. Focal neocortical infarction was established using the middle cerebral artery occlusion (MCAO) method. Secondary damage in the ipsilateral thalamus was assessed by Nissl staining and immunostaining. The expression of Nogo-A, NgR1, Rho-A and Rho-associated coiled-coil containing protein kinase 1 (ROCK1) as well as autophagic flux were evaluated by immunofluorescence and immunoblotting. The roles of Nogo-A-NgR1 signaling in autophagic activation were determined by intraventricular delivery of an NgR1 antagonist peptide, NEP1-40, at 24 h after MCAO. The results showed that Nogo-A and NgR1 overexpression temporally coincided with marked increases in the levels of Beclin1, LC3-II and sequestosome 1 (SQSTM1)/p62 in the ipsilateral thalamus at seven and fourteen days after MCAO. In contrast, NEP1-40 treatment significantly reduced the expression of Rho-A and ROCK1 which was accompanied by marked reductions of LC3-II conversion as well as the levels of Beclin1 and SQSTM1/p62. Furthermore, NEP1-40 treatment significantly reduced neuronal loss and gliosis in the ipsilateral thalamus, and accelerated somatosensory recovery at the observed time-points after MCAO. These results suggest that blockade of Nogo-A-NgR1 signaling inhibits autophagic activation, attenuates secondary neuronal damage in the ipsilateral thalamus, and promotes functional recovery after focal cerebral cortical infarction.

Regional Shape Abnormalities in Thalamus and Verbal Memory Impairment After Subcortical Infarction.

Background. Subcortical infarcts can result in verbal memory impairment, but the potential underlying mechanisms remain unknown. Objective. We investigated the spatiotemporal deterioration patterns of brain structures in patients with subcortical infarction and identified the regions that contributed to verbal memory impairment. Methods. Cognitive assessment and structural magnetic resonance imaging were performed 1, 4, and 12 weeks after stroke onset in 28 left-hemisphere and 22 right-hemisphere stroke patients with subcortical infarction. Whole-brain volumetric analysis combined with a further-refined shape analysis was conducted to analyze longitudinal morphometric changes in brain structures and their relationship to verbal memory performance. Results. Between weeks 1 and 12, significant volume decreases in the ipsilesional basal ganglia, inferior white matter, and thalamus were found in the left-hemisphere stroke group. Among those 3 structures, only the change rate of the thalamus volume was significantly correlated with that in immediate recall. For the right-hemisphere stroke group, only the ipsilesional basal ganglia survived the week 1 to week 12 group comparison, but its change rate was not significantly correlated with the verbal memory change rate. Shape analysis of the thalamus revealed atrophies of the ipsilesional thalamic subregions connected to the prefrontal, temporal, and premotor cortices in the left-hemisphere stroke group and positive correlations between the rates of those atrophies and the change rate in immediate recall. Conclusions. Secondary damage to the thalamus, especially to the left subregions connected to specific cortices, may be associated with early verbal memory impairment following an acute subcortical infarct.

EphrinB2 activation enhances angiogenesis, reduces amyloid-ß deposits and secondary damage in thalamus at the early stage after cortical infarction in hypertensive rats.

Cerebral infarction causes secondary neurodegeneration and angiogenesis in thalamus, which impacts functional recovery after stroke. Here, we hypothesize that activation of ephrinB2 could stimulate angiogenesis and restore the secondary neurodegeneration in thalamus after cerebral infarction. Focal cerebral infarction was induced by middle cerebral artery occlusion (MCAO). Secondary damage, angiogenesis, amyloid-ß (Aß) deposits, levels of ephrinB2 and receptor for advanced glycation end product (RAGE) in the ipsilateral thalamus were determined by immunofluorescence and immunoblot. The contribution of ephrinB2 to angiogenesis was determined by siRNA-mediated knockdown of ephrinB2 and pharmacological activation of ephrinB2. The results showed that formation of new vessels and ephrinB2 expression was markedly increased in the ipsilateral thalamus at seven days after MCAO. EphrinB2 knockdown markedly suppressed angiogenesis coinciding with increased Aß accumulation, neuronal loss and gliosis in the ipsilateral thalamus. In contrast, clustered EphB2-Fc significantly enhanced angiogenesis, alleviated Aß accumulation and the secondary thalamic damage, which was accompanied by accelerated function recovery. Additionally, activation of ephrinB2 significantly reduced RAGE levels in the ipsilateral thalamus. Our findings suggest that activation of ephrinB2 promotes angiogenesis, ameliorates Aß accumulation and the secondary thalamic damage after cerebral infarction. Additionally, RAGE might be involved in Aß clearance by activating ephrinB2 in the thalamus.

Unfolded protein response is activated in the ipsilateral thalamus following focal cerebral infarction in hypertensive rats.

Focal cerebral cortical infarction causes secondary neurodegeneration in the remote regions, such as the ventroposterior nucleus of the thalamus. Retrograde degeneration of thalamocortical fibers is considered as the principle mechanism, but the exact molecular events remain to be elucidated. This study aimed to investigate whether unfolded protein response (UPR) is activated in thalamic neurons following distal middle cerebral artery occlusion (MCAO) in stroke-prone renovascular hypertensive rats. Immunostaining and immunoblotting were performed to evaluate the expression of Grp78 and its downstream effectors in the thalamus at 3, 7 and 14 days after MCAO. Secondary thalamic degeneration was assessed with Nissl staining and NeuN immunostaining. Neuronal death was not apparent at 3 days post-ischaemia but was evident in the thalamus at 7 and 14 days after MCAO. Grp78 level was reduced in the ipsilateral thalamus at 3 and 7 days after MCAO. In parallel, phosphorylated eIF2α and ATF4 levels were elevated, indicating the activation of UPR. In contrast, ATF6α and CHOP levels were not changed. These results suggest that UPR is activated before neuronal death in the ipsilateral thalamus after MCAO and may represent a key early event in the secondary thalamic degeneration.

Tongxinluo Enhances Neurogenesis and Angiogenesis in Peri-Infarct Area and Subventricular Zone and Promotes Functional Recovery after Focal Cerebral Ischemic Infarction in Hypertensive Rats.

Background. Tongxinluo is a traditional Chinese medicine compound with the potential to promote the neuronal functional recovery in cerebral ischemic infarction. Objective. This study aimed to disclose whether tongxinluo promotes neurological functional recovery and neurogenesis and angiogenesis in the infarcted area and SVZ after cerebral ischemic infarction in hypertensive rats. Methods. The ischemic model was prepared by distal middle cerebral artery occlusion (MCAO) in hypertensive rats. Tongxinluo was administrated 24 h after MCAO and lasted for 3, 7, or 14 days. Behavioral tests were performed to evaluate the protection of tongxinluo. Immunochemical staining was applied on brain tissue to evaluate the effects of tongxinluo on neurogenesis and vascularization in the MCAO model rats. Results. Postinjury administration of tongxinluo ameliorated the neuronal function deficit in the MCAO model rats. As evidenced by the immunochemical staining, BrdU(+)/DCX(+), BrdU(+)/nestin(+), and BrdU(+) vascular endothelial cells were promoted to proliferate in SVZ after tongxinluo administration. The matured neurons stained by NeuN and vascularization by laminin staining were observed after tongxinluo administration in the peri-infarct area. Conclusion. Tongxinluo postischemia administration could ameliorate the neurological function deficit in the model rats. Possible mechanisms are related to neurogenesis and angiogenesis in the peri-infarct area and SVZ.

Tongxinluo attenuates neuronal loss and enhances neurogenesis and angiogenesis in the ipsilateral thalamus and improves neurological outcome after focal cortical infarction in hypertensive rats.

PURPOSE: Tongxinluo, a well-known traditional Chinese medicine complex, has been widely used for the treatment of cerebrovascular diseases in China. The present study was to explore whether treatment with tongxinluo could improve neurological function and alleviate secondary damage in the ipsilateral thalamus after focal cortical infarction in hypertensive rats. METHODS: Tongxinluo was given through oral gavage starting 24 h after distal middle cerebral artery occlusion (MCAO). Neurological function was assessed and then rats were sacrificed 7 and 14 days after MCAO. Brains were harvested for examining infarction volume, Nissl staining and immunofluorescence analysis. RESULTS: Compared with vehicle treatment, tongxinluo remarkably improved neurological function without reducing infarction volume, attenuated neuronal loss and astrocyte activation in the ipsilateral thalamus 7 and 14 days after MCAO (all p < 0.05). Also, tongxinluo markedly increased the number of BrdU+/nestin+ and BrdU+/NeuN+ cells 14 days after MCAO. Moreover, vascular density, the number of BrdU+ vascular endothelial cells, and vascular perimeter in the ipsilateral thalamus were markedly increased in the tongxinluo group relative to that of the vehicle group (all p < 0.05). CONCLUSION: Administration of tongxinluo 24 h after cortical infarction may promote neurogenesis and angiogenesis in the ipsilateral thalamus and improves neurological function after cortical infarction in rats.

Cerebrolysin reduces amyloid-ß deposits, apoptosis and autophagy in the thalamus and improves functional recovery after cortical infarction.

Focal cerebral infarction causes amyloid-ß (Aß) deposits and secondary thalamic neuronal degeneration. The present study aimed to determine the protective effects of Cerebrolysin on Aß deposits and secondary neuronal damage in thalamus after cerebral infarction. At 24h after distal middle cerebral artery occlusion (MCAO), Cerebrolysin (5 ml/kg) or saline as control was once daily administered for consecutive 13 days by intraperitoneal injection. Sensory function and secondary thalamic damage were assessed with adhesive-removal test, Nissl staining and immunofluorescence at 14 days after MCAO. Aß deposits, activity of ß-site amyloid precursor protein-cleaving enzyme 1 (BACE1), apoptosis and autophagy were determined by TUNEL staining, immunofluorescence and immunoblot. The results showed that Cerebrolysin significantly improved sensory deficit compared to controls (p<0.05). Aß deposits and BACE1 were obviously reduced by Cerebrolysin, which was accompanied by decreases in neuronal loss and astroglial activation compared to controls (all p < 0.05). Coincidently, Cerebrolysin markedly inhibited cleaved caspase-3, conversion of LC3-II, downregulation of Bcl-2 and upregulation of Bax in the ipsilateral thalamus compared to controls (all p<0.05). These findings suggest that Cerebrolysin reduces Aß deposits, apoptosis and autophagy in the ipsilateral thalamus, which may be associated with amelioration of secondary thalamic damage and functional recovery after cerebral infarction.

Autophagosomes accumulation is associated with ß-amyloid deposits and secondary damage in the thalamus after focal cortical infarction in hypertensive rats.

Focal cerebral cortical infarction after distal middle cerebral artery occlusion causes ß-amyloid deposition and secondary neuronal degeneration in the ipsilateral ventroposterior nucleus of the thalamus. Several studies suggest that autophagy is an active pathway for ß-amyloid peptide generation. This study aimed to investigate the role of autophagy in thalamic ß-amyloid deposition and neuronal degeneration after cerebral cortical infarction in hypertensive rats. At 7 and 14days after middle cerebral artery occlusion, neuronal death and ß-amyloid deposits were evident in the ipsilateral ventroposterior nucleus, and the activity of ß-site amyloid precursor protein (APP)-cleaving enzyme 1, required for ß-amyloid peptide generation, was elevated in the thalamus. In correlation, both the number of cells showing punctate microtubule-associated protein 1A light chain 3 fluorescence and levels of light chain 3-II protein, an autophagosome marker, were markedly increased. Notably, most of the cells that over-expressed ß-site APP-cleaving enzyme 1 displayed punctate light chain 3 staining. Furthermore, the inhibition of autophagy with 3-methyladenine significantly reduced the thalamic neuronal damage, ß-amyloid deposits, and ß-site APP-cleaving enzyme 1 activity. These results suggest that autophagosomes accumulate within thalamic cells after cerebral cortical infarction, which is associated with thalamic ß-amyloid deposition and secondary neuronal degeneration via elevation of ß-site APP-cleaving enzyme 1 level.

Beclin 1 knockdown inhibits autophagic activation and prevents the secondary neurodegenerative damage in the ipsilateral thalamus following focal cerebral infarction.

Cerebral infarction can cause secondary degeneration of thalamus and delay functional recovery. However, the mechanisms underlying secondary degeneration are unclear. The present study aimed to determine the occurrence and contribution of autophagy to the thalamic degeneration after cerebral infarction. Focal cerebral infarction was induced by distal middle cerebral artery occlusion (MCAO). Autophagic activation, Beclin 1 expression and amyloid ß (Aß) deposits were determined by immunofluorescence, immunoblot and electron microscopy. Secondary damage to thalamus was assessed with Nissl staining and immunofluorescence analysis. Apoptosis was determined using TUNEL staining. The contribution of autophagy to the secondary damage was evaluated by shRNA-mediated downregulation of Beclin 1 and the autophagic inhibitor, 3-methyladenine (3-MA). The potential role of Aß in autophagic activation was determined with N-[N-(3, 5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). The results showed that the conversion of LC3-II, the formation of autophagosomes, and the levels of activated cathepsin B and Beclin 1 were significantly increased in the ipsilateral thalamus at 7 and 14 days after MCAO (p < 0.05 or 0.01). Both Beclin 1 knockdown and 3-MA treatment significantly reduced LC3-II conversion and autophagosome formation, which were accompanied by obvious decreases in neuronal loss, gliosis and apoptosis in the ipsilateral thalamus (p < 0.05 or 0.01). Additionally, DAPT treatment markedly reduced Aß deposits, which coincided with decreases in LC3-II conversion and autophagosome formation (p < 0.01). These results suggest that inhibition of autophagy by Beclin 1 knockdown can attenuate the secondary thalamic damage after focal cerebral infarction. Furthermore, Aß deposits may be involved in the activation of autophagy.

Decrease of tight junction integrity in the ipsilateral thalamus during the acute stage after focal infarction and ablation of the cerebral cortex in rats.

1. Whether damage to the blood-brain barrier (BBB) occurs in remote areas after a focal cortical lesion remains unknown. The present study investigated tight junction-related proteins and tight junction microstructure in the ipsilateral thalamus during the acute stage after middle cerebral artery occlusion (MCAO) and cortical aspiration lesion (CAL) in rats. 2. Thirty-six hypertensive and normotensive rats were subjected to MCAO or CAL; another 18 rats in each group were submitted to sham operation. Zonula Occluden (ZO)-1, occludin and albumin were detected by western blotting 12 and 24 h after surgery. Tight junction microstructure was evaluated using electron microscopy, whereas albumin location in the ipsilateral thalamus was determined using double immunostaining for albumin and occludin or albumin and neuronal nuclei (NeuN) 24 h after surgery. 3. Twenty-four hours after MCAO or CAL, occludin expression was reduced to 78.4% and 81.3%, respectively, compared with control. A reduction in ZO-1 expression in the ipsilateral thalamus (to 79%) was seen only after CAL (P < 0.05). Membrane contact at the tight junction was discontinuous in the ipsilateral thalamus in both MCAO and CAL rats. Albumin levels were 23.2% and 82.5% higher in the ipsilateral thalamus after MCAO and CAL, respectively (P < 0.05). The percentage of the albumin-positive area that coincided with the occludin-positive area in the MCAO and CAL groups was 76.8% and 64.6%, respectively, indicating that albumin was mainly localized around the microvessels. 4. The results of the present study suggest that tight junction integrity decreases during the acute stage in the ipsilateral thalamus after MCAO and CAL in rats.