Adequate nutrient intake mitigate the toxic effects of bromate on the rotifer Brachionus calyciflorus

Bromate is receiving increased attention as a typical disinfection by-product in aquatic environments, but bromate toxicity tests on invertebrate such as Brachionus calyciflorus rotifer are inadequate. In the present study, the long-term toxicity tests on B. calyciflorus were performed during 21 days under the exposure of different bromate concentrations and two algal density conditions. Furthermore, we evaluated the feeding behaviors of the rotifers under the impact of bromate. The maximum population density of rotifers was significantly reduced at 100 and 200 mg/L bromate exposure at the two algal density conditions. However, we observed that the maximum population density and population growth rate of rotifers were higher at 3.0 × 106 cells/mL algal density than those at 1.0 × 106 cells/mL under the same conditions of bromate exposure. These results suggest that higher food density may have alleviated the negative effects of bromate on rotifers. Meanwhile, the ingestion rate at an algal density of 3.0 × 106 cells/mL was higher than that at 1.0 × 106 cells/mL. The present study provides a basic reference to comprehensively evaluate the toxic effects of bromate on aquatic organisms.

Effects of spatial variation in water quality and hydrological factors on environmental flows

Environmental flow is the quantity, timing, and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-being that depend on these ecosystems. Environmental flows (e-flows) are crucial parameters for ecosystem restoration. Understanding the effects of spatial variation in the hydrological and water quality factors on e-flows aids the determination of recovery prior areas and helps to improve the success rate of ecosystem restoration projects. However, few studies have investigated the effects, which severely hinder the restoration of aquatic ecosystems and the sustainable use of water resources in inland waters. This paper therefore presents a framework for studying such effects. Spatial autocorrelation, a geostatistical method, is used to analyze the spatial variation in the hydrological and water quality factors and to further analyze the effects of various factors on the spatial heterogeneity of e-flows. Four different methods including the Tennant method, wetted perimeter method, AEHRA, and integrated water quality method are integrated to comprehensively evaluate e-flows. The former three methods consider the demands of biota on the streamflow, whereas the latter considers the demands on both the streamflow and the water quality. The results show that the Tennant and wetted perimeter methods, which focus on the statistics of only streamflow, result in similar spatial distribution of e-flows; the AEHRA and integrated water quality method, which consider the effects of water quality and other hydrological factors such as flow velocity and water depth on fish, also result in a similar spatial variation. Consideration of both demands on the hydrological factors and the water quality environmental factors makes the integrated water quality method more practical, particularly in developing regions with excessive pollutant discharge into rivers. In addition, spatial variation in the hydrological and water quality factors influenced the presence of principal fish species and consequently affected the e-flows. Of the 37 water quality factors identified, water transparency had a negative impact on e-flow because the increase in transparency could reduce the number of principal fish species. Of the four hydrological factors, flow velocity and river width had positive impacts on fish because the increase in flow velocity can provide breeding sites and habitats for more fish, respectively, both of which result in increases in the numbers of principal fish species. We found that spatial variation in the hydrology and water quality factors had a profound impact on the living environments of aquatic organisms; negative changes in these factors lowered the survival probability of principal species, which changed the hierarchy and structure of the ecosystems and thus led to variation in e-flows. The results can provide priori knowledge for e-flow methods selection and a reference for ecosystem restoration helping improve the success rate of project elsewhere in the world.

[COVID-19 pandemic: global epidemiological trends and China's subsequent preparedness and responses]

The outbreak of COVID-19 has spread quickly across 114 countries/territories/areas in six continents worldwide and has been announced as a pandemic by WHO. This study analyzed global COVID-19 epidemiological trends, examined impact of the pandemic on global health security, diplomacy, and social environment in China, and provided short- and long-term strategic policy recommendations for China's subsequent preparedness and responses.

Streamflow calculation for medium-to-small rivers in data scarce inland areas

Inland streamflow estimation is essential in global water supply and environment protection. In data-scarce areas a highly efficient way of estimating streamflow is through remote sensing methods. However, high requirement of most previous methods on ground-measured data hinder their wide use in data-scarce areas. Therefore, this paper presented a new framework for estimation of streamflow in medium-to-small rivers with few ground measurements by using high-resolution unmanned aerial vehicle (UAV) imagery. A new Virtual Hydraulic Radius (VHR) method was proposed to complement AMHG (at-many-stations hydraulic geometry), a method not requiring any ground measurements when global parameters are used (global-AMHG) in large-scaled rivers but yielding great uncertainties in smaller scaled rivers, thus creating a VHR-AMHG method for medium-to-small rivers. The accuracy verification of the proposed method was performed by comparing it to field measurement data and the global parameters of the original AMHG (global-AMHG). Results showed that the root mean square error calculated from VHR-AMHG was 32.15 m³/s, while that from global-AMHG was 305.65 m³/s, indicating that the VHR-AHRG method yields a significantly higher accuracy for streamflow estimation for medium-to-small rivers. We found that regardless of the size of the river, AMHG is not applicable for rivers having excessively small b values in the equation w = aQ^b (low-b rivers). For medium-to-small rivers with b < 0.25, AMHG is not recommended. The accuracy of the original AMHG method is limited by the initial value of the model parameters and the condition that the congruent discharge (Q_c) has to be within the range of observational discharge. The initial value setting of the model parameters significantly impacts the calculation accuracy. The VHR-AMHG method is able to overcome the deficiencies of the original AMHG, i.e. being overly dependent on the initial value setting with long-series known discharge data. It also eliminates the limitation of the Q_c condition, as it achieves a higher accuracy for rivers in which Q_c does not satisfy the condition compared to using global-AMHG on rivers that actually meet the condition, thus greatly expanding its usage scope. Thus VHR-AMHG method can provide detailed data on the spatial and temporal distribution of regional and national streamflow for governments and stakeholders, and offer scientific data support for wisely making water supply polices and sustainably protecting eco-environment.

Predicting cyanobacteria bloom occurrence in lakes and reservoirs before blooms occur

With increased global warming, cyanobacteria are blooming more frequently in lakes and reservoirs, severely damaging the health and stability of aquatic ecosystems and threatening drinking water safety and human health. There is an urgent demand for the effective prediction and prevention of cyanobacterial blooms. However, it is difficult to effectively reduce the risks and loss caused by cyanobacterial blooms because most methods are unable to successfully predict cyanobacteria blooms. Therefore, in this study, we proposed a new cyanobacterial bloom occurrence prediction method to analyze the probability and driving factors of the blooms for effective prevention and control. Dominant cyanobacterial species with bloom capabilities were initially determined using a dominant species identification model, and the principal driving factors of the dominant species were then analyzed using canonical correspondence analysis (CCA). Cyanobacterial bloom probability was calculated using a newly-developed model, after which, the probable mutation points were identified and thresholds for the principal driving factors of cyanobacterial blooms were predicted. A total of 141 phytoplankton data sets from 90 stations were collected from six large-scale hydrology, water-quality ecology, integrated field surveys in Jinan City, China in 2014-2015 and used for model application and verification. The results showed that there were six dominant cyanobacterial species in the study area, and that the principal driving factors were water temperature, pH, total phosphorus, ammonia nitrogen, chemical oxygen demand, and dissolved oxygen. The cyanobacterial blooms corresponded to a threshold water temperature range, pH, total phosphorus (TP), ammonium nitrogen level, chemical oxygen demand, and dissolved oxygen levels of 19.5-32.5 °C, 7.0-9.38, 0.13-0.22 mg L^-1, 0.38-0.63 mg L^-1, 10.5-17.5 mg L^-1, and 4.97-8.28 mg L^-1, respectively. Comparison with research results from other global regions further supported the use of these thresholds, indicating that this method could be used in habitats beyond China. We found that the probability of cyanobacterial bloom was 0.75, a critical point for prevention and control. When this critical point was exceeded, cyanobacteria could proliferate rapidly, increasing the risk of cyanobacterial blooms. Changes in driving factors need to be rapidly controlled, based on these thresholds, to prevent cyanobacterial blooms. Temporal and spatial scales were critical factors potentially affecting the selection of driving factors. This method is versatile and can help determine the risk of cyanobacterial blooms and the thresholds of the principal driving factors. It can effectively predict and help prevent cyanobacterial blooms to reduce the global probability of occurrence, protect the health and stability of water ecosystems, ensure drinking water safety, and protect human health.

Quantitative assessment of the effects of human activities on phytoplankton communities in lakes and reservoirs

Global algal blooms have been severely threatening safety of drinking water and development of socio-economy. Effective prevention and accurate control of algal blooms require a quantitative assessment of the influence of human activities and identification of priority areas. However, previous studies on the quantitative assessment of the effects of human activities on algal communities are lacking, severely hindering the effective and precise control of algal blooms. This paper proposes a quantitative assessment model to evaluate the impact intensity of human activities on phytoplankton. Applications showed that the proliferation of phytoplankton were more limited by nutrients such as total phosphorus and ammonia where waters are less influenced by human activities, yet were less limited by these nutrients where there are highly intensive human activities. The density of phytoplankton in waters increased with an increase in human activity intensity, particularly in concentrated agricultural areas, which are priority areas for the prevention and control of algal blooms. The methodologies can clearly identify key areas for algal bloom prevention and control and can provide scientific evidence for water and nutrient management throughout the world, reducing the risk of algal blooms and ensuring aquatic ecosystem health and potable water safety.

Impact of spatial variations in water quality and hydrological factors on the food-web structure in urban aquatic environments

Global aquatic ecosystems are essential to human existence and have deteriorated seriously in recent years. Understanding the influence mechanism of habitat variation on the structure of the food-web allows the effective recovery of the health of degraded ecosystems. Whereas most previous studies focused on the selection of driving habitat factors, the impact of habitat variation on the food-web structure was rarely studied, resulting in the low success rate of ecosystem restoration projects globally. This paper presents a framework for exploring the effects of spatial variations in water quality and hydrological habitat factors on the food-web structure in city waters. Indices for the evaluation of the food-web structure are first determined by integrating model-parameter extraction via literature refinement. The key water quality and hydrological factors are then determined by coupling canonical correspondence analysis with partial least squares regression. Their spatial variation is investigated using spatial autocorrelation. Finally, fuzzy clustering is applied to analyze the influence of the spatial variations in water quality and hydrological factors on the food-web structure. The results obtained in Ji'nan, the pilot city of water ecological civilization in China, show that the Shannon diversity index, connectance index, omnivory index, and the ratio of total primary production to the total respiration are important indicators of food-web structural change. They show that the driving factors affecting the aquatic food-web structure in Ji'nan are hydrological factors (e.g., river width, water depth, and stream flow), physical aspects of water quality (e.g., air temperature, water temperature, electrical conductivity, and transparency), and chemical aspects (e.g., potassium, dissolved oxygen, calcium, and total hardness). They also show that the stability of the food-web is more prone to spatial variations in water quality than in hydrological factors. Higher electrical conductivity, potassium, total hardness, and air temperature lead to deteriorated food-web structures, whereas better transparency improves structure and stability. We found that water and air temperature are the most important factors in the spatial variation of the food-web structure in the study area, followed by total hardness. Transparency is the least important factor. Large disparities and varied spatial distributions exist in the driving effects of water quality and hydrological factors across regions attributable to differences in geographical environments, water salinity (fresh vs. sea water), and environmental factors (e.g., water pollution). The above methods and results serve as a theoretical and scientific basis for a high success rate of aquatic ecosystem restoration projects in the study area and other cities worldwide.

Predicting future river health in a minimally influenced mountainous area under climate change

It has been shown that climate change impacts the overall health of a river's ecosystem. Although predicting river health under climate change would be useful for stakeholders to adapt to the change and better conserve river health, little research on this topic exists. This paper presents a methodology predicting river health under different climate change scenarios. First, a multi-source, distributed, time-variant gain hydrological model (MS-DTVGM) was used to predict the runoff from a mountainous river in eastern China using the data from three existing IPCC5 climate change models (RCP2.6, RCP4.5, and RCP8.4). Next, a model was developed to predict the river's water quality under these scenarios. Finally, a multidimensional response model utilizing hydrology, water quality, and biology was used to predict the river's biological status and ascertain the impact of climate change on its overall health. The river is in a mountainous area near Jinan City, one of China's first "pilot" cities recognized as a "healthy water ecological community." Our results predict that the overall health of the Yufu River, which is minimally influenced by human activities, will improve by 2030 due to the increased river flow due to an increase in rainfall frequency and subsequent peak runoff. However, the total nitrogen concentration is predicted to increase, which is a potential eutrophication risk. Therefore, effective control of nitrogen pollutants entering the river will be necessary. The increase in flow velocity (the annual average increase is ~0.5 m/s) is favorable for fish reproduction. Our methods and results will provide scientific guidance for policy makers and river managers and will help people to better understand how global climate change impacts river health.

Inhibition of Nkcc1 promotes axonal growth and motor recovery in ischemic rats

Bumetanide is a selective inhibitor of the Na⁺-K⁺-Cl^--co-transporter 1(NKCC1). We studied whether bumetanide could affect axonal growth and behavioral outcome in stroke rats. Adult male Wistar rats were randomly assigned to four groups: sham-operated rats treated with vehicle or bumetanide, and ischemic rats treated with vehicle or bumetanide. Endothelin-1 was used to induce focal cerebral ischemia. Bumetanide administration (i.c.v.) started on postoperative day 7 and continued for 3 weeks. Biotinylated dextran amine (BDA) was injected into the right imotor cortex on postoperative day 14 to trace corticospinal tract (CST) fibers sprouting into the denervated cervical spinal cord. Nogo-A, NKCC1, KCC2 and BDNF in the perilesional cortex and BDA, PSD-95 and vGlut1 in the denervated spinal cord were measured by immunohistochemistry and/or Western blot. Behavioral outcome of rats was assessed by the beam walking and cylinder tests. The total length of CST fibers sprouting into the denervated cervical spinal cord significantly increased after stroke and bumetanide further increased this sprouting. Bumetanide treatment also decreased the expressions of NKCC1 and Nogo-A, increased the expressions of KCC2 and BDNF in the perilesional cortex and enhanced the synaptic plasticity in the denervated cervical spinal cord after cerebral ischemia. The behavioral performance of ischemic rats was significantly improved by bumetanide. In conclusion, bumetanide promoted post-stroke axonal sprouting together accompanied by an improved behavioral outcome possibly through restoring and maintaining neuronal chloride homeostasis and creating a recovery-promoting microenvironment by overcoming the axonal growth inhibition encountered after cerebral ischemia in rats.

Preparation of silver nanoparticles with antimicrobial activities and the researches of their biocompatibilities

Silver nanoparticles were prepared by chemical reduction method using chitosan as stabilizer and ascorbic acid as reducing agent in this work. The silver/chitosan nanocomposites were characterized in terms of their particle sizes and morphology by using UV spectrophotometer, nano-grainsize analyzer, and transmission electron microscopy. Antibacterial activities of these nanocomposites were carried out for Staphylococcus aureus and Escherichia coli. The silver nanoparticles exhibited significantly inhibition capacity towards these bacteria. Detailed studies on the biocompatibility of the silver/chitosan nanocomposites were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell adhesion test. The results indicated that these silver/chitosan nanocomposites were benefit for the proliferation and adhesion of L-929 cells, and the biocompatibilities between the nanocomposites and the cells would become better with the culturing days. We anticipated that these silver/chitosan nanocomposites could be a promising candidate as coating material in biomedical engineering and food packing fields wherein antibacterial properties and biocompatibilities are crucial.

In vitro study on the influence of strontium-doped calcium polyphosphate on the angiogenesis-related behaviors of HUVECs

Angiogenesis is of great importance in bone tissue engineering, and has gained large attention in the past decade. Strontium-doped calcium polyphosphate (SCPP) is a novel biodegradable material which has been proved to be able to promote in vivo angiogenesis during bone regeneration. An in vitro culture system was developed in the present work to examine its influence on angiogenesis-related behaviors of human umbilical vein endothelial cells (HUVECs), including cell adhesion, spreading, proliferation and migration. The effects of microtopography, chemical property and the ingredients in the degradation fluid (DF) on cell behaviors were discussed. The results showed that cells attached and spread better on SCPP scaffold than on calcium polyphosphate (CPP), which might partially result from the less rough surface of SCPP scaffold and the less hydrogel formed on the surface. In addition, cell proliferation was significantly improved when treated with SCPP DF compared with the treatment with CPP DF. Statistical analysis indicated that Sr(2+) in SCPP DF might be the main reason for the improved cell proliferation. Moreover, cell migration, another important step during angiogenesis, was evidently stimulated by SCPP DF. The improved in vivo angiogenesis by SCPP might be assigned to its better surface properties and strontium in the DF. This work also provides a new method for in vitro evaluation of biodegradable materials' potential effects on angiogenesis.

Changes in brain content of nociceptin/orphanin FQ and endomorphin 2 in a rat model of neuropathic pain

Orphanin FQ (OFQ) and endomorphins (EM) are newly characterized members of opioid peptide family. OFQ has been shown to antagonize morphine analgesia at supraspinal level, whereas endomorphins are highly selective endogenous ligands for mu receptor, showing analgesic effect at both spinal and supraspinal level. OFQ and EM-2 (EM2) immunoreactivity (ir) was measured by radioimmunoassay in nociception-related brain areas of rats subjected to L5/L6 spinal nerve ligation, using sham operated rats as control. It was found that: (1) the content of EM2-ir of spinal nerve ligated rats showed a significant increase (778%) in periaqueductal gray (PAG), and a significant decrease (43%) in striatum, compared with the control group. (2) a significant increase of the content of OFQ-ir was found in amygdala (+841%) and PAG (+459%), respectively in spinal nerve ligated rats. High pressure liquid chromatography showed that the EM2-ir and OFQ-ir were both heterogeneous with the major part eluting at the position of EM2 and OFQ standard, respectively. These results suggest that spinal nerve ligation induces significant changes in the content of EM2-ir and OFQ-ir in some discrete brain areas, which may play a role in nociceptive modulation.

Nocistatin, a peptide reversing acute and chronic morphine tolerance

It has been reported that intracerebroventricular (i.c.v.) injection of nociception/orphanin FQ (OFQ) can antagonize morphine analgesia, whereas i.c.v. OFQ antibody can reverse morphine tolerance. Nocistatin (NST) is a recently characterized neuropeptide possessing an antagonizing effect on OFQ. Here we examine whether i.c.v. NST would result in a reversal of morphine tolerance. The results showed that: (1) i.c.v. NST at doses of 0.005, 0.05, 0.5, 5 or 50 ng per rat produced a bell-shaped dose-dependent reversal of chronic morphine tolerance, with maximum response at 0.5 ng. (2) Acute morphine tolerance could also be reversed, albeit partially, by i.c.v. NST at 0.5 ng. (3) The reversal of acute and chronic morphine tolerance by NST was completely abolished when NST (0.5 ng) was co-injected with (8 microg) OFQ. Since OFQ and NST are derived from the same preprohormone, the profile of its splicing in the CNS may play an important role in determining the effectiveness of morphine analgesia.

[Study on the release mechanism of fenoprofen calcium from hydrophillic sustained-release matrix]

AIM

To study the release mechanism of fenoprofen calcium (FC) from hydroxypropylmethylcellulose (HPMC) matrices.

METHODS

The release of FC and the erosion properties of hydrophillic matrices containing HPMC was examined at different paddle speed. The release mechanism of FC was further confirmed by evaluating the n value in Peppas equation.

RESULTS

The results indicate that the release of FC and the erosion of matrices exhibit zero order kinetic equation, and it exhibits line relationship between them.

CONCLUSION

In the first 40 min, FC mainly released by diffusion and erosion from HPMC matrix, while it was controlled by the rate of tablet erosion after 50 min.

An evaluation of a polyethersulfone hollow fiber plasma separator by animal experiment

Membrane plasma separators are being used routinely for therapy in various diseases. In this study, a newly developed plasma separator made of polyethersulfone (PES) hollow fibers was evaluated for its plasma filtration efficiency and blood compatibility by animal experiment. Hemolysis did not occur under the usual conditions of plasma separation. The sieving coefficients of total protein and albumin were over 95%, and the total cholesterol was over 90% throughout the perfusions. Decreases in white blood cells, platelets, fibrinogen, and coagulation factors were observed during the early stage of plasma separation, but appear to be within acceptable ranges for clinical use.

Nocistatin reverses the effect of orphanin FQ/nociceptin in antagonizing morphine analgesia

Nocistatin is a recently characterized neuropeptide derived from the preprohormone containing nociceptin (Orphanin FQ, OFQ). Nocistatin was reported to antagonize OFQ induced allodynia, hyperalgesia and prostaglandin E2-elicited pain responses. The aim of the present study was to determine whether nocistatin, injected intracerebroventricularly (i.c.v.), would reverse the anti-morphine effect of OFQ in rats using the tail-flick latency (TFL) as the nociceptive index. I.c.v. injection of nocistatin at doses of 0.005, 0.05, 0.5, 5, 50, and 500 ng produced no significant changes in the basal TFL, nor did it affect morphine analgesia. However, it significantly reversed the antagonistic effect of OFQ on morphine analgesia when co-injected i.c.v. at doses of 0.05, 0.5, 5, 50 and 500 ng per rat with OFQ. The dose-response curve was bell-shaped and the most effective dose was 0.5 ng. The results suggest that nocistatin can reverse the anti-morphine effect of OFQ in rat brain.

Review of 140 patients with brain abscess

There were 140 cases of brain abscess treated between 1980 (when CT scanning became available) and June 1991. These arose by spread of a contiguous area of infection in 37%, and from another identified cause in 22%; the origin was undetermined in 41%. There were multiple abscesses in 11%. The abscess was < 2 cm in diameter in 21%. In two-thirds of the patients, the intracranial pressure was raised, there were localizing neurologic signs in 33%, and in 28% there were epileptic seizures. The computed tomographic (CT) feature of an abscess in the capsular stage was a thin, regular, and uniform, ring-like enhancement. In the cerebritis stage, nine out of 17 patients showed a uniform enhancement throughout the lesion. Since 1989, 14 cases have been investigated with magnetic resonance imaging (MRI). In 11, the abscess was in the capsular stage. In both T1- and T2-weighted images, the abscess and the surrounding inflammatory area were well demonstrated, and with T2-weighting, the capsule showed a low-intensity signal clearly. In the three abscesses in the cerebritis stage, there was a uniform abnormality with indistinct margins between the abscess, inflammatory edema, and surrounding grey and white matter. All cases received a combination of wide-spectrum antibiotics before the organism was identified; and later the medication was administered according to bacteriologic indication of the organism of 112 cases, organisms were identified in 71%, with anaerobic organisms occurring in 30% of these. In 127 cases, surgical treatment was used: either repeated aspiration, excision or both. We treated 13 cases that had small, early, or multiple abscesses with antibiotics only. The mortality with surgical treatment was 7.9%, and no case treated conservatively died.

[Analysis of urinary citrate and oxalate in 42 diabetics]

Among 42 diabetics, there were 32 with the disease remaining uncontrolled after treatment. Their fasting blood glucose was 15.24 +/- 5.37 mmol/L (mean +/- S), urinary glucose 42.6 +/- 47.83 g/24 hr, urinary oxalate 0.43 +/- 0.16 mmol/24 hr and urinary citrate 3.60 +/- 2.28 mmol/24 hr All of these levels were higher than those in a control group (P less than 0.001). Urinary citrate level was significantly positively correlated with fasting blood glucose level (gamma = 0.3954, P less than 0.001). In the remaining 10 diabetics with the disease controlled after treatment the fasting blood glucose was 7.04 +/- 0.92 mmol/L, urinary citrate 1.92 +/- 0.96 mmol/24 hr and urinary oxalate 0.37 +/- 0.11 mmol/24 hr. All of these levels were significantly lower than those before treatment (P less than 0.01) and were not different from those in the control group (P greater than 0.05). This explains that urinary citrate and oxalate increased when diabetes is uncontrolled as a result of accelerated decomposition due to increased metabolism. Urinary oxalate level is correlated positively with that of urinary citrate (gamma = 0.3773, P less than 0.05). Urinary oxalate and citrate are good index reflecting diabetic metabolic changes. Analysis of urinary oxalate with ion-chromatography is accurate and rapid method worthy to be used clinically.