The adsorption and release mechanism of different aged microplastics toward Hg(II) via batch experiment and the deep learning method

Aged microplastics are ubiquitous in the aquatic environment, which inevitably accumulate metals, and then alter their migration. Whereas, the synergistic behavior and effect of microplastics and Hg(II) were rarely reported. In this context, the adsorptive behavior of Hg(II) by pristine/aged microplastics involving polystyrene, polyethylene, polylactic acid, and tire microplastics were investigated via kinetic (pseudo-first and second-order dynamics, the internal diffusion model), Langmuir, and Freundlich isothermal models; the adsorption and desorption behavior was also explored under different conditions. Microplastics aged by ozone exhibited a rougher surface attached with abundant oxygen-containing groups to enhance hydrophilicity and negative surface charge, those promoted adsorption capacity of 4-20 times increment compared with the pristine microplastics. The process (except for aged tire microplastics) was dominated by a monolayer chemical reaction, which was significantly impacted by pH, salinity, fulvic acid, and co-existing ions. Furthermore, the adsorbed Hg(II) could be effectively eluted in 0.04% HCl, simulated gastric liquids, and seawater with a maximum desorption amount of 23.26 mg/g. An artificial neural network model was used to predict the performance of microplastics in complex media and accurately capture the main influencing factors and their contributions. This finding revealed that aged microplastics had the affinity to trap Hg(II) from freshwater, whereafter it released the Hg(II) once transported into the acidic medium, the organism's gastrointestinal system, or the estuary area. These indicated that aged microplastics could be the sink or the source of Hg(II) depending on the surrounding environment, meaning that aged microplastics could be the vital carrier to Hg(II).

Red cell distribution in critically ill patients with chronic obstructive pulmonary disease

BACKGROUND

Red blood cell distribution width (RDW) is associated with increased mortality risk in patients with chronic obstructive pulmonary disease (COPD). However, limited data are available for critically ill patients with COPD.

METHODS

Data from the Medical Information Mart for Intensive Care III V1.4 database were analyzed in this retrospective cohort research. The International Classification of Diseases codes were used to identify critically ill patients with COPD. The first value of RDW was extracted within the first 24 h after intensive care unit admission. The endpoint was 28-day all-cause mortality. Multivariable logistic regression analysis was performed to examine the relationship between RDW and 28-day mortality. Age, sex, ethnicity, anemia status, comorbidities, clinical therapy, and disease severity score were considered for subgroup analysis.

RESULTS

A total of 2,344 patients were included with mean (standard deviation) age of 72.3 (11.3) years, in which 1,739 (53.6%) patients were men. The increase in RDW was correlated with an increased risk of 28-day mortality in the multivariate logistic regression model (odds ratio [OR] 1.15; 95% confidence interval [CI] 1.09-1.21). In comparison with the low-RDW group, the middle and high-RDW groups tended to have higher risks of 28-day all-cause mortality (OR [95% CI] 1.03 [0.78-1.34]; OR [95% CI] 1.70 [1.29-2.22]; P trend < 0.0001). Subgroup analyses show no evidence of effect modifications on the correlation of RDW and 28-day all-cause mortality.

CONCLUSION

An increase in RDW was associated with an increased risk of 28-day all-cause mortality in critically ill patients with COPD. Further studies are required to investigate this association.

Coupling isotopic signatures and partial extraction method to examine lead pollution in mangrove sediments

Elevated lead (Pb) has been widely observed in mangrove sediments due to human activities, yet understanding the sources of Pb in these sediments and the factors influencing Pb accumulation is challenging. Here, we combined Pb isotopes with partial extraction methods to study Pb contamination levels in mangrove sediments from the eastern and western parts of the Maowei Sea, China. Our results showed that the Pb in the leachate and residual fraction was mainly from anthropogenic and natural sources, respectively. The use of 204Pb isotope analysis can reveal some overlooked differences between anthropogenic and natural sources. Calculation by Bayesian mixing model showed no significant difference in the total anthropogenic contribution between the two sites, but the relative contribution of each end member differed. The contribution of Pb/Zn ores was much higher in the eastern sites (30.9 ± 5.1%) than in the west (18.4 ± 5.5%), while that of agricultural activities was much lower in the east (5.2 ± 3.1%) than in the west (13.5 ± 4.6%). The elevated anthropogenic Pb accumulation in mangrove sediments was ascribed to organic matter. This study provides more data on Pb isotopic composition and new insights into Pb biogeochemistry in the mangrove environment.

Bifunctional Role of Monocyte Subsets in Modulating Radiotherapy Combined Intra-Tumor αCD40 Agonist Induced Abscopal Effect

PURPOSE/OBJECTIVE(S)

Abscopal effect induced by radiotherapy and immune checkpoint blockade is a promising yet far from satisfactory strategy in clinical. The underlying immune mechanism, especially driven by monocytes remains poorly undefined. Monocytes consist of two phenotypically and functionally distinct subsets distinguished by expression of chemokine receptors CCR2 and CX3CR1: classical inflammatory Ly6ChiCCR2hi monocytes and nonclassical patrolling Ly6CloCCR2loCX3CR1hi monocytes. Monocytes differentiate and transit to other myeloid cells such as dendritic cells and macrophages according to various environmental cues. Herein we investigated the roles of monocyte subsets in modulating tumor control consisting of combination RT and myeloid checkpoint agonist αCD40 to specifically ignite myeloid cell activation.

MATERIALS/METHODS

To establish abscopal model, contralateral tumors were implanted in each mouse, while only one side were treated with RT (8 Gy × 3) + αCD40 agonist (50 μg, intra-tumor). Tumor volume and mice survival were compared in each group (control, RT, αCD40 and RT + αCD40). Ccr2RFP/+ Cx3cr1GFP/+ (R2 × 3), Ccr2RFP/RFPCx3cr1+/+ (R2-KO) and Ccr2+/+Cx3cr1GFP/GFP (X3-KO) mice were used for cell tracking and to dissect chemokine receptor CCR2 and CX3CR1 on monocyte. Tumor infiltrating immune cells were analyzed by flowcytometry and RNA-seq.

RESULTS

RT combined with αCD40 significantly dampened tumor growth on both ipsilateral and contralateral sides in abscopal model (p< 0.01), accompanied by upregulation of chemokine receptors CCR2 and CX3CR1 on myeloid cells were both increased in tumor and peripheral blood. Chemokine ligands CCL2, CCL3, CCL5, CCL7, CCL12 and CX3CL1 were upregulated in tumor after RT and αCD40 treatment, recruiting CCR2 and CX3CR1 expressing monocytes in situ. To elucidate the roles of CCR2 and CX3CR1 in mediating local and systemic anti-tumor immunity, R2 × 3, R2-KO and X3-KO mice with combined treatment were used. Tumor size on ipsilateral leg were similar among groups. However, tumor growth was significantly delayed on contralateral side in X3-KO mice while accelerated in R2-KO mice compared with that in R2 × 3 mice. Mechanistically, remarkable decrease of antigen presenting dendritic cells (MHCII+Ly6ChiCD11c+) were observed in R2-KO mice. Moreover, phagocytosis was strengthened in macrophages (F4/80+CD11b+) of X3-KO mice.

CONCLUSION

CX3CR1 deletion ignite anti-tumor immunity elicited by RT and αCD40 through enhanced phagocytosis in macrophages, while CCR2 deletion renders inferior tumor control through reduction of dendritic cells. Preferential targeting nonclassical patrolling monocyte may lead to enhanced local and systemic tumor control.

Determining effect of seagrass-mediated CO2 flux on the atmospheric cooling potential of a subtropical intertidal seagrass meadow

Atmospheric greenhouse gas (GHG) emissions from seagrass meadows that determine the ecosystem atmospheric cooling effect have rarely been quantified. This study measured the simultaneous fluxes direct to the atmosphere of three GHGs (CO₂, CH₄ and N₂O) within a Halophila beccarii seagrass meadow and an adjacent unvegetated bare intertidal flat, and their relationships to seagrass abundance and relevant soil parameters. The results showed that seasonal variation in seagrass abundance was strongly linked with the CO₂ exchange rate. The CH₄ and N₂O fluxes were similarly low at both sites and comparable between winter and summer. The global warming potential of CH₄ and N₂O reduced the ecosystem CO₂ uptake by only 5 % at the seagrass site. The results indicated that the H. beccarii meadow had a stronger atmospheric cooling effect than the bare flat and that the seagrass-mediated CO₂ flux in this oligotrophic seagrass meadow primarily determined the atmospheric cooling effect.

Acupuncture combined with exercise training at different time points on nerve repair of cerebral ischemia-reperfusion injury in rats and its effects on the expressions of Nestin, bFGF and EGF

OBJECTIVE

The aim of the study was to observe the neuroreparative effect of electroacupuncture in rats with cerebral ischemia-reperfusion injury, and to explore the difference in the therapeutic effect of acupuncture on different acupoint groups after cerebral ischemia-reperfusion.

MATERIALS AND METHODS

Experimental rats were randomly divided into: sham operation group, model group, electroacupuncture group, rehabilitation group, and Diankang group (electroacupuncture + rehabilitation training). There were 24 rats in each group, and the focal cerebral ischemia-reperfusion model was established by Zea-Longa suture method. After modeling, it took 4 hours to electroacupuncture at Baihui and Dazhui points, which was used to observe the changes of nerve function in rats with signs of keel nerve function defect. Protein expression was detected by immunohistochemistry.

RESULTS

Compared with the model group, the EA 3d, 7d, 10d groups and the rehabilitation group had no significant difference in promoting the expression of Nestin (p>0.05). There was a significant difference (p<0.01). After cerebral ischemia-reperfusion injury, the expression of bFGF and EGF on the ischemic side was stronger. The peak of bFGF expression appeared earlier, and the peak of EGF expression appeared later. The expression of bFGF and EGF in cerebral ischemic cortex at different time points of ischemia in electroacupuncture group, rehabilitation group and Diankang group was increased, and the response was enhanced. The effect of Diankang group on the upregulation of bFGF and EGF was more significant (p<0.01, p<0.05).

CONCLUSIONS

Under the influence of different effects, Diankang is superior to simple treatment in improving ischemic neurological dysfunction. This may be related to the fact that Diankang can promote the proliferation of neural stem cells and the expression of neurotrophic factors on the ischemic side of the rat brain.

[Effects and mechanism of pressure treatment on hemodynamic changes in patients with hypertrophic scar secondary to extensive burns]

Objective: To investigate the hemodynamic changes of the main arteries and veins of the extremities and the heart in patients with hypertrophic scar secondary to extensive burns after pressure treatment, and to analyze the relevant mechanisms. Methods: A retrospective before-after self-control study was conducted. From January 2017 to February 2022, 37 patients with hypertrophic scar secondary to extensive burns who met the inclusion criteria were hospitalized in the Burn Rehabilitation Department of Guangdong Industrial Injury Rehabilitation Hospital, including 25 males and 12 females, aged 23-52 years. The patients were admitted to the hospital within 12 weeks after wound healing, and within one week after admission, rehabilitation therapists, occupational therapists, and tailors custom-made pressure products such as full-body pressure garment, pressure pants, vests, split finger gloves, split finger socks, hoods, and plastic collars, with the pressure at each part maintained at 2.67-4.00 kPa when wearing. Before the first treatment with pressure products (hereinafter referred to as before pressure treatment) and at 1 h of the first treatment with pressure products (hereinafter referred to as 1 h of pressure treatment), color Doppler ultrasonography was performed to check the pulse rate of the axillary artery, the lumen diameter, peak systolic velocity (PSV), and resistance index of the axillary artery and femoral artery on the left side, the lumen diameter, cross-sectional area, and average blood flow velocity of the axillary vein and femoral vein, and the mitral valve E peak, mitral valve A peak, tricuspid valve E peak, aortic valve PSV, and pulmonary valve PSV of the heart; an optical chromatographic skin detector was used to detect the red color, red pigment, and surface brightness of the scar on the back of the hand to reflect the filling and distribution of the scar microvessels. Data were statistically analyzed with paired sample t test. Results: Compared with those before pressure treatment, the PSV of the axillary artery of patients was significantly slowed down at 1 h of pressure treatment (t=55.42, P<0.01); the average blood flow velocity of the axillary vein was significantly accelerated (t=-60.50, P<0.01); the pulse rate, lumen diameter, and resistance index of the axillary artery, as well as the lumen diameter and cross-sectional area of the axillary vein did not change obviously (P>0.05); the average blood flow velocity of the femoral vein was significantly accelerated (t=-80.52, P<0.01); the lumen diameter, PSV, and resistance index of the femoral artery, as well as the lumen diameter and cross-sectional area of the femoral vein had no significant change (P>0.05); the mitral valve E peak and mitral valve A peak of the heart decreased significantly (with t values of 10.71 and 21.96, respectively, P<0.01); the tricuspid valve E peak of the heart increased significantly (t=7.57, P<0.01); the PSV of the aortic valve and pulmonary valve of the heart did not change obviously (P>0.05). At 1 h of pressure treatment, the red color and red pigment values of the scar on the back of the hand of patients were 15.3±1.1 and 16.8±1.2, respectively, which were significantly lower than 24.5±1.3 and 23.8±1.2 before pressure treatment (with t values of 8.32 and 8.04, respectively, P<0.01). The brightness value of the scar surface on the back of the hand of patients at 1 h of pressure treatment was similar to that before pressure treatment (P>0.05). Conclusions: After pressure treatment for the hypertrophic scar in patients secondary to extensive burn, the average blood flow velocity of the axillary vein and femoral vein in patients are obviously accelerated, the PSV of the axillary artery is significantly slowed down, the peak values of mitral valve E and mitral valve A of the heart are significantly decreased, and the tricuspid valve E peak is significantly increased. These hemodynamic changes may be related to the reduction of microvascular blood flow in the local area of scar after systemic pressure treatment.

Development and validation of the DGT technique using the novel cryogel for measuring dissolved Hg(II) in the estuary

The complex seawater matrix has significantly influenced the determination of estuarine dissolved Hg(II), hindering its monitoring and risk assessment in maricultural areas. In this work, SiO2-SH-DGT assembled by the sulfhydryl-modified silica cryogel (SiO2-SH cryogel) as the novel binding phase was developed to tackle this problem. The uniform dispersion of the cryogel into binding gel was advantageous for achieving remarkable and comparable capacity, which endowed the estimated diffusion coefficient (D) to be 1.39-3.08 times of the existing research. The SiO2-SH-DGT performance was independent of pH (3-9), ionic strength (10-800 mM), fulvic acid at low content, and seawater matrix (Na+, K+, Ca2+, Cl-), but the high content of Mg2+ did interfere with the Hg(II) accumulation, which manifested as competitive adsorption and diffusion. Therefore, the calibrated model was established by calibrating accumulated mass (M') and diffusion coefficient (D') based on the Mg2+ concentration, its high accuracy was further verified in the lab. Finally, SiO2-SH-DGT was deployed in the three typical aquaculture areas in Beibu Gulf, field trials achieved the actual Hg(II) level to be 1.52-5.38 ng/L with consideration of the diffusion boundary layer. The finding could provide new thought and technical support for metal pollution monitoring in estuary maricultural areas.

Short-Term Exposure to MPs and DEHP Disrupted Gill Functions in Marine Bivalves

The synergistic impact of microplastics (MPs) and organic pollutants remains poorly understood in the marine environment. This study aimed to assess the toxicity of polypropylene microplastics (PS) and/or di-(2-ethylhexyl) phthalate (DEHP) on marine clams. Both Ruditapes philippinarum and Tegillarca granosa were exposed to PS and DEHP individually and combined at environmentally relevant concentrations for 48 h. The filtration rate, antioxidant enzymes activity, lipid peroxidation, reactive oxygen species accumulation, and histological alterations were evaluated. Our results show that single or co-exposure to MPs and DEHP significantly decreases the filtration rate in both type of clams, but the latter exhibited stronger inhibition effect. Close examination of accumulation of reactive oxygen species and related biomarkers revealed that combined exposure exerts greater oxidative stress in the cells, which causes more serious histopathological damage in the gills of the bivalves. Our study implies that MPs, in synergy with organic pollutants, can be more harmful for marine organisms.

Mechanisms of Metal Tolerance in Halophytes: A Mini Review

Industrialization and urbanization of coastal wetlands have caused metal pollution worldwide. Phytoremediation has been widely used for treating soil and water pollution, and halophytes are considered a promising remediation method to address metal pollution. However, application of halophytes in phytoremediation is still in its infancy. To increase awareness of halophytes, the metal accumulation, tolerance, and mechanisms of metal detoxification in halophytes are reviewed here. Several halophytes are considered as potential candidates for phytoremediation because they have strong accumulation capacity of metals.

Adsorption of di (2-ethylhexyl) phthalate (DEHP) to microplastics in seawater: a comparison between pristine and aged particles

Microplastics (MPs) are a widely distributed pollutant and have been attracting global attention. The increasing abundance of MPs in marine environments has raised concern about their adverse effects on marine organisms and influence on the fate of contaminants in seawater. In this study, we investigated the effects of natural aging on the adsorption of di (2-ethylhexyl) phthalate (DEHP), one of the most widely used phthalic acid esters (PAEs), in two types of MPs (polyethylene and polystyrene). Biofilm was observed on the surface of MPs after 3-month exposure in seawater. Atomic force microscopy revealed there were significant physical changes in the MPs after aging. Aging in coastal seawater for 3 months significantly reduced the MPs' surface roughness and adhesion, and increased the Young's modulus at the same time. Adsorption isotherms of DEHP indicated that aged MPs had stronger binding capacity of the organic contaminant than pristine MPs. Our data shed some light on the biogeochemical role of MPs in marine environments.

Prevalence and distribution of domoic acid and cyclic imines in bivalve mollusks from Beibu Gulf, China

Beibu Gulf is an important shellfish aquaculture area in the northwest of the South China Sea, China. In this study, the toxin profile and spatial-temporal distribution of domoic acid (DA) and 10 lipophilic phycotoxins were systematically analyzed in the bivalve mollusks collected in Beibu Gulf from October 2018 to October 2020. Neurotoxin DA was first detected in the mollusks from the investigative regions with a prevalence of 17.7%, peaking at 401 µg kg^-1. Cyclic imines (CIs) including gymnodimine-A (GYM-A, 46.6%) and 13-desmethyl-spirolide-C (SPX1, 15.8%) predominated the lipophilic phycotoxins in shellfish, peaking at 10.1 µg kg^-1 and 19.6 µg kg^-1, respectively. Gymnodimine-A partially accompanied by SPX1 was detected in all batches of shellfish samples, suggesting that Alexandrium ostenfeldii and Karenia selliformis were possible sources of CIs-group toxins in Beibu Gulf. During the investigative period, relatively higher levels of DA occurred in shellfishes from March to August, while slightly higher contents of CIs in mollusks appeared in October and December. Spatial distribution of the targeted phycotoxins demonstrated that shellfishes tended to accumulate relatively higher contents of toxins in Lianzhou, Qinzhou and Tieshan bays.

Control of phytoplankton by oysters and the consequent impact on nitrogen cycling in a Subtropical Bay

Although there has been growing interest in using oysters to remediate estuarine eutrophication since the 1980s, the role of oysters in remediation remains controversial. In this study, we took advantage of the intensive oyster farming in a nutrient-enriched estuary to evaluate the control of phytoplankton blooms by oysters. Observing the phytoplankton density variations in March and October, we found that despite doubled nutrient levels in March, oysters kept the phytoplankton density low. This is the first estuary-scale evidence that oysters can effectively suppress phytoplankton blooms. Measuring the isotopic signals in seawater revealed the significant impact of pelagic nitrogen cycling in the estuary. In March, oysters facilitated NO₃^- removal in the water column by enhancing the coupled phytoplankton assimilation-oyster filtration and denitrification in the sediments. While in October, the oysters-related nitrification could outcompete the removal processes, adding a significant amount of NO₃^- to the water column. Our study illustrates the influence of massive oysters on pelagic nitrogen cycling in an "oyster-remediated" estuary, providing implications for restoring oyster reefs to mitigate the symptoms of estuarine eutrophication.

The distribution of microplastics in water, sediment, and fish of the Dafeng River, a remote river in China

Although rivers are one of the dominant pathways by which microplastics reach the oceans, reports on remote rivers are rare. Dafeng River is located in Guangxi Province, China, is an important water source and a habitat of a coastal dolphin, Sousa chinensis, which is a first-class national protected animal in China. In this study, we determined the distribution and characteristics of microplastics in the surface water, sediment, and fish of the river. During the dry and rainy seasons, the microplastics content of the surface water ranged from 3 × 10-4-2.5 × 10-3 items/L (7 × 10-4-0.12 items/m2) and 4 × 10-5-9 × 10-4 items/L (2 × 10-3-2.8 × 10-2 items/m2), while those in the sediment samples ranged from 9.4 to 50.3 items/kg (dry weight) and 0.0-21.3 items/kg, respectively. The pollution level during the dry season was approximately two to three times higher than that during the rainy season (P < 0.05). The estimated annual load of microplastics carried by the Dafeng River flow was 8.3 × 108 particles. The microplastics pollution in the Dafeng River was closely related with residential activities. The contents of microplastics in the digestive tracts and gills of fish ranged from 8 × 102 to 5.7 × 103 items/kg (0.3-6.7 items/individual) and 2 × 102 to 1.7 × 103 items/kg (0.1-3.0 items/individual), respectively. The proportion of blue particles in fish was significantly higher than that in the water and sediment, which may indicate that they prefer blue-colored items. The microplastics pollution levels in the water, sediment, and fish of the Dafeng River decreased in the following order: fish > sediment > surface water in terms of items/kg. The level of microplastics pollution in the Dafeng River was relatively low; however, that in aquatic organisms was more severe. Our work highlights the requirement for concern towards microplastics pollution in the organisms of remote rivers.

Pollution and ecological risk assessment, and source identification of heavy metals in sediment from the Beibu Gulf, South China Sea

The Beibu Gulf is an important passageway between China and the Association of Southeast Asian Nations, where there has been an increase in pollution of heavy metals (HMs). High concentrations of Pb, Cr, Cd, Cu, Zn, As, and Hg in surface sediment were found in Qinzhou Bay, Fangchenggang, and other coastal areas. Stochastic geo-accumulation analyses identified the pollution to be "uncontaminated"; however, it had an 18% probability of deterioration. The Cd, Hg, and As pollution were relatively serious. Principal component analysis, positive matrix factor model, and mercury isotopes demonstrated that the HMs could mainly be attributed to industrial sources including petrochemical, coal-fired, metal and metalloid processing, leather tanning, and human activities: anthropogenic sources accounted for approximately 70% of all the contaminations. This study demonstrates the contribution of terrigenous input to HMs even at a low level and provides basic data for the coordinated development of land and marine resources.

Litterfall-derived organic matter enhances mercury methylation in mangrove sediments of South China

Mercury (Hg) contamination in mangrove ecosystems has received increasing attention in recent years. Although many studies have investigated methylmercury (MeHg) contamination and its relationship to a number of environmental factors in mangrove sediments, the production of MeHg in this carbon-rich ecosystem has not been fully evaluated. In this study, we measured the total mercury (THg) and MeHg concentrations in the sediments collected from seven mangrove forests in China. In addition, we examined the origin and quality of sedimentary organic matter (OM), trying to evaluate their influence on the MeHg accumulation in mangrove sediments. We found that litterfall played an important role in regulating THg and MeHg contents in mangrove sediments. THg and MeHg concentrations in the mangrove sediments were positively correlated to OM content and the labile fraction of the OM. Multiple evidence (stable carbon isotopes, monosaccharide compositions, and biogenic silica) suggested that OM in mangrove sediments was dominated by input from litterfall. THg and MeHg concentrations were elevated at the sediments with higher input of mangrove OM. We observed that addition of mangrove litter stimulated the production of MeHg under anaerobic conditions. Overall, our results suggested that litterfall acted as a source of inorganic Hg, labile carbon, and low-molecular-weight OM which greatly favor the Hg methylation. Our study provides new insights into the MeHg production in mangrove sediments.

Long-term trends of microplastics in seawater and farmed oysters in the Maowei Sea, China

Microplastic pollution in marine environments and organisms has received a great deal of international attention. However, the long-term field studies of microplastics are rare. Here, we assessed annual variation in microplastic abundance in the Maowei Sea, a classic mariculture bay in southern China, and analyzed the long-term accumulation in oyster tissues. U-shaped time trends of microplastics in water were observed from January to December in 2018 in the estuarine region, inner bay, and mouth bay sites, representing an inverse relationship with the local rainfall patterns. The common microplastic particles in Maowei Sea are PET/PE fibers, and polystyrene foams, which are mainly related to textile pollution and fishery activities. After one year of continuous monitoring, we did not find accumulation of microplastics in the whole soft tissues of oyster after 10% KOH digestion. No significant correlation of microplastic abundances between water and oysters was observed. The microplastic abundance in oyster was correlated with some environmental variables (i.e. salinity, pH, nutrients and total organic carbon) of the surrounding water following Spearman correlation analysis. The microplastic levels in oysters could probably be influenced by the environmental variables.

Isotopic Composition Reveals the Impact of Oyster Aquaculture on Pelagic Nitrogen Cycling in a Subtropical Estuary

To offset estuarine eutrophication, interest is increasing in restoring oyster reefs and expanding oyster aquaculture. However, ecosystem-scale evidence is lacking on oyster assemblages' impacts on estuarine pelagic nitrogen (N) cycling. Using a multiple-isotope approach and isotope-mixing model, we examined the sources, transformations, and influence of intensive oyster aquaculture on N pollution in a subtropical estuary. The salinity-dependent NO₃^- and NH₄⁺ concentrations and their correlations with isotopic signals (δ¹⁵N-NO₃^-, δ¹⁸O-NO₃^-, δ¹⁵N-NH₄⁺) indicated the nutrient spatial distribution in low-salinity areas was largely regulated by mixing between freshwater and seawater. However, the intensive oyster aquaculture greatly increased nitrification in the estuary. In high-salinity areas where oyster assemblages were absent, the assimilation of NO₃^- by phytoplankton became dominant and sharply increased the δ¹⁵N-NO₃^- and δ¹⁸O-NO₃^-. Soil organic nitrogen and fertilizer, domestic sewage, and wastewater treatment plants were the major NO₃^- sources in the estuary, while internal nitrification contributed 20.6% to the NO₃^- pool. Oyster biodeposits comprised up to one-third of the particulate organic matter in the water column, and as much as 47.3% of the NH₄⁺ pool could be from the oysters. Our study shows that oysters significantly contribute to the pelagic nutrient pools and N transformations, adding an important dimension to our understanding of oyster assemblages' impacts on estuarine N cycling.

Neutral monosaccharides and their relationship to metal contamination in mangrove sediments

Mangrove sediments act as an important natural sink and a secondary source for trace metals. The main objective of this study was to investigate metal contamination and its relationship to mangrove-derived carbohydrates in mangrove sediments. Sixteen metals (Be, V, Cr, Co, Ni, Cu, Zn, Ga, As, Sr, Cd, Sn, Sb, Ba, Tl, and Pb）were analyzed in the surface sediments from four sites at different latitudes on the southeast coastline of China. The sedimentary organic matter was characterized by Rock-Eval pyrolysis, and the neutral sugars were examined by gas chromatograph mass spectrometry. Our results from the enrichment factors indicated that the mangrove sediments were no enriched by Ga, Sr, and Ba, minor enriched by Be, V, Cr, Co, Ni, Cu, Zn, As, Sn, Sb, Tl, and Pb, and moderate enriched by Cd. Litterfall was a major source of organic matter in the mangrove sediments, and the neutral sugars were mainly derived from this litterfall. Significant correlations were detected between the total organic carbon, pyrolytic parameters, neutral sugars, and enrichment factors of V, Cr, Co, Ni, Zn, and Cd, suggesting the input of neutral carbohydrates played an important role in enhancing the metal accumulation in the mangrove sediments. The mangrove litterfall itself was a major source of metals for the sediments, and the mangrove-derived organic matter enhanced the sediment's metal accumulation.

Bulk sedimentary phosphorus in relation to organic carbon, sediment textural properties and hydrodynamics in the northern Beibu Gulf, South China Sea

Bulk sedimentary phosphorus (P) is studied to evaluate its source, distribution, preservation and enrichment in relation with organic carbon (OC), sediment textures and moisture contents in the northern Beibu Gulf. Approximately 80% of surface sediments in the investigated sites were composed of coarse sandy texture (>63 μm). Total P (TP), inorganic P (IP) and organic P (OP) contents were lower to medium range compared to the levels reported for other marginal seas. Sedimentary OC and P were derived from mixed sources, with high terrestrial influence in the coastal areas (molar OC/OP ratios >250:1). The distribution of P corroborated with the variation tendency of fine-grained sediments, moisture contents and OC. Both IP and OP may significantly influence the trophic state of seawater if released from surface sediments. Influenced by hydrodynamics, frequent resuspension and high abundance of sand, TP is less preserved, and shows low to moderate enrichment in surface sediments.

Microplastic pollution in the Maowei Sea, a typical mariculture bay of China

The ingestion of microplastics by organisms presents a potential exposure route for humans via seafood consumption. Although mariculture has become an essential source of seafood worldwide, the content of microplastics in the mariculture zone has received less scrutiny than in the wild environment. The Maowei Sea is a semi-closed bay that is rich in fishery resources. The specific levels of microplastics in the Maowei Sea and its fishery products remain undetermined. In this paper, we detail the distributions and characteristics of microplastics in the aquaculture water and biota of the Maowei Sea. Microplastics were detected in the range of 1.2-10.1 particles/L in Maowei Sea surface water, with high microplastic content in estuarine oyster nursery (10.1 particles/L) and Qinzhou harbor (8.8-9.5 particles/L) sites. In water samples from the three inflowing rivers, the abundances ranged from 2.9 to 4.5 particles/L, which is comparable to that in Maowei Sea surface water. Of 66 collected fish belonging to 12 species, microplastics were observed in all of the gastrointestinal tracts (GITs) and in the gills of 40 individuals. In the GIT and gill tests, the abundances of microplastics ranged from 2.0 to 14.0 and from 0.0 to 8.5 particles/individual, respectively. The enhanced particles/individual figures in the GIT relative to the gill are particularly noteworthy. Demersal species showed significantly higher abundances of microplastics than pelagic species (p < 0.05). Microplastics were also detected in the soft tissues of all oyster samples, with abundances ranging from 3.2 to 8.6 particles/individual. The microplastic composition was dominated by rayon and polyester and tended to be white in color and fibrous in shape. Altogether, these results correspond to high levels of microplastics in the Maowei Sea. As the study region is a mariculture bay, the observed microplastics contamination in its fishery products presents a route for human exposure. CAPSULE ABSTRACT: Microplastics are widespread in the aquaculture water and biota in the Maowei Sea, a mariculture bay.

Bulk Fermi Surfaces of the Dirac Type-II Semimetallic Candidates MAl_{3} (Where M=V, Nb, and Ta)

We report a de Haas-van Alphen (dHvA) effect study on the Dirac type-II semimetallic candidates MAl_{3} (where, M=V, Nb and Ta). The angular dependence of their Fermi surface (FS) cross-sectional areas reveals a remarkably good agreement with our first-principles calculations. Therefore, dHvA supports the existence of tilted Dirac cones with Dirac type-II nodes located at 100, 230 and 250 meV above the Fermi level ϵ_{F} for VAl_{3}, NbAl_{3} and TaAl_{3} respectively, in agreement with the prediction of broken Lorentz invariance in these compounds. However, for all three compounds we find that the cyclotron orbits on their FSs, including an orbit nearly enclosing the Dirac type-II node, yield trivial Berry phases. We explain this via an analysis of the Berry phase where the position of this orbit, relative to the Dirac node, is adjusted within the error implied by the small disagreement between our calculations and the experiments. We suggest that a very small amount of doping could displace ϵ_{F} to produce topologically nontrivial orbits encircling their Dirac node(s).

Dynamic change in natural killer cell type in the human ocular mucosa in situ as means of immune evasion by adenovirus infection

The most severe form of virus-induced inflammation at the ocular surface is epidemic keratoconjunctivitis (EKC), often caused by group D human adenoviruses (HAdVs). We investigated the dynamics and mechanisms of changes in natural killer (NK) cell types in the human ocular mucosal surface in situ over the course of infection. In the acute phase of infection, the mature CD56(dim)NK cells that comprise a major subpopulation in the normal human conjunctiva are replaced by CD56(bright)NK cells recruited to the ocular surface by chemokines produced by the infected epithelium, and NKG2A-expressing CD56(dim) and CD56(bright) NK cells become the major subpopulations in severe inflammation. These NK cells attracted to the mucosal surface are however incapable of mounting a strong antiviral response because of upregulation of the inhibitory ligand human leukocyte antigen-E (HLA-E) on infected epithelium. Furthermore, group D HAdVs downregulate ligands for activating NK cell receptors, thus rendering even the mature NKG2A(-)NK cells unresponsive, an immune-escape mechanism distinct from other adenoviruses. Our findings imply that the EKC-causing group D HAdVs utilize these multiple pathways to inhibit antiviral NK cell responses in the initial stages of the infection.

146 CO-CULTURE OF EARLY CLEAVAGE STAGE IVP EMBRYOS WITH BOVINE OVIDUCT EPITHELIAL CELLS DOES NOT IMPROVE EMBRYO DEVELOPMENT OR PREGNANCY RATES

Pregnancy rates after the transfer of bovine IVP embryos are lower than that achieved after the transfer of MOET embryos. One reason may be that the relatively defined IVC (SOFaaBSA) culture system used in vitro is suboptimal for embryo development. We investigated whether the co-culture of early stage IVP embryos with bovine oviduct epithelial cell (BOEC) to Day 3 could provide some of the missing substrates and improve both embryo production and subsequent pregnancy rates after embryo transfer. COCs were collected by ovum pickup (OPU) from donor Brahman females, transported overnight at 38.5°C to the laboratory in HEPES-IVM media, then fertilized and cultured by our standard IVP methodology (Fry et al. 2003 Theriogenology 59, 446). Briefly, the IVC was carried out at 38.5°C in a humidified atmosphere of 5% CO2, 5% O2, 90% N2 in 4-well Nunc dishes in 500 μL of SOFaaBSA media overlayed by 500 μL of mineral oil. After 3 days of culture, the embryos were transferred to fresh IVC media and after 6 days placed in 5-mL Falcon tubes (Becton Dickinson Labware, Lincoln, NJ, USA) in fresh IVC media containing 2% FCS for overnight shipment. All grade 1 and 2 embryos were transferred to synchronized recipients on Day 7. Pregnancy diagnosis was between Days 50-90. In the BOEC treatment group, frozen aliquots of BOEC were thawed, seeded at 300,000 cells/mL, and grown for 2 days to 60-80% confluence in the Nunc wells in 500μL of DMEM/F12 media containing 10% FCS. On the first day of embryo culture, the media was removed and replaced by IVC media prior to the introduction of presumptive zygotes. After 3 days of co-culture, the embryos were transferred to fresh IVC media and thereafter cultured and transferred as for the Control group. In the Control group, 80 OPU sessions produced 1277 COCs (mean 16.0) of which 1064 (81.6%) cleaved producing 385 (33.7%) transferable embryos. Of the 337 embryos transferred to recipients (48 were vitrified), 141 (40.1%) resulted in pregnancies. In the BOEC group, 73 OPU sessions produced 1111 COCs (mean 15.2) of which 891 (80.2%) cleaved producing 388 (35%) transferable embryos that resulted in 161 (41.5%) pregnant recipients after transfer. Chi-square analysis showed no difference in either IVP embryo production or subsequent pregnancy rate between the Control group or the group where the IVP embryo was co-cultured for the first 3 days with BOEC.

Lack of association between HLA-A, -B and -DRB1 alleles and the development of SARS: a cohort of 95 SARS-recovered individuals in a population of Guangdong, southern China

Severe acute respiratory syndrome (SARS), caused by infection with a novel coronavirus (SARS‐CoV), was the first major novel infectious disease at the beginning of the 21st century, with China especially affected. SARS was characterized by high infectivity, morbidity and mortality, and the confined pattern of the disease spreading among the countries of South‐East and East Asia suggested the existence of susceptible factor(s) in these populations. Studies in the populations of Hong Kong and Taiwan showed an association of human leucocyte antigen (HLA) polymorphisms with the development and/or severity of SARS, respectively. The aim of the present study was to define the genotypic patterns of HLA‐A, ‐B and ‐DRB1 loci in SARS patients and a co‐resident population of Guangdong province, southern China, where the first SARS case was reported. The samples comprised 95 cases of recovered SARS patients and 403 unrelated healthy controls. HLA ‐A, ‐B and ‐DRB1 alleles were genotyped using polymerase chain reaction with sequence‐specific primers. The severity of the disease was assessed according to the history of lung infiltration, usage of assisted ventilation and occurrence of lymphocytopenia. Although the allelic frequencies of A23, A34, B60, DRB1*12 in the SARS group were slightly higher, and A33, ‐B58 and ‐B61 were lower than in the controls, no statistical significance was found when the Pc value was considered. Similarly, no association of HLA alleles with the severity of the disease was detected. Thus, variations in the major histocompatibility complex are unlikely to have contributed significantly to either the susceptibility or the severity of SARS in the population of Guangdong.

The effect of lidocaine on in vitro neutrophil and endothelial adhesion molecule expression induced by plasma obtained during tourniquet-induced ischaemia and reperfusion

BACKGROUND

Changes in neutrophil and endothelial adhesion molecule expression occur during perioperative ischaemia and reperfusion (I/R) injury. We investigated the effects of lidocaine on neutrophil-independent changes in neutrophil and endothelial adhesion molecule expression associated with tourniquet-induced I/R.

METHODS

Plasma was obtained from venous blood samples (tourniquet arm) taken before (baseline), during, 15 min, 2 and 24 h following tourniquet release in seven patients undergoing elective upper limb surgery with tourniquet application. Isolated neutrophils from healthy volunteers (n = 7) were pretreated in the presence or absence of lidocaine (0.005, 0.05 and 0.5 mg mL(-1) for 1 h, and then incubated with I/R plasma for 2 h. Human umbilical vein endothelial cells (HUVECs) were pretreated in the presence or absence of lidocaine (0.005, 0.05 and 0.5 mg mL(-1)) for 1 h, and then incubated with the plasma for 4 h. Adhesion molecule expression was estimated using flow cytometry. Data were analysed using ANOVA and post hoc Student-Newman-Keuls tests.

RESULTS

I/R plasma (withdrawn 15 min following tourniquet release) increased isolated neutrophil CD11b (P = 0.03), CD18 (P = 0.01) and endothelial intercellular adhesion molecule-1 (ICAM-1) (P = 0.008) expression compared to baseline. CD11b, CD18 and ICAM-1 expression on lidocaine (0.005 mg mL(-1)) treated neutrophils was similar to control. CD11b (P < 0.001), CD18 (P = 0.03) and ICAM-1 (P = 0.002) expression on lidocaine (0.05 mg mL(-1)) treated neutrophils and HUVECs was less than that on controls.

CONCLUSION

Increased in vitro neutrophil and endothelial cell adhesion molecule expression on exposure to plasma obtained during the early reperfusion phase is diminished by lidocaine at greater than clinically relevant plasma concentrations.

The effect of lidocaine on neutrophil CD11b/CD18 and endothelial ICAM-1 expression and IL-1beta concentrations induced by hypoxia-reoxygenation

BACKGROUND

Lidocaine has actions potentially of benefit during ischaemia-reperfusion. Neutrophils and endothelial cells have an important role in ischaemia-reperfusion injury.

METHODS

Isolated human neutrophil CD11b and CD18, and human umbilical vein endothelial cell (HUVEC) ICAM-1 expression and supernatant IL-1beta concentrations in response to hypoxia-reoxygenation were studied in the presence or absence of different concentrations of lidocaine (0.005, 0.05 and 0.5 mg mL(-1)). Adhesion molecule expression was quantified by flow cytometry and IL- 1beta concentrations by ELISA. Differences were assessed with analysis of variance and Student-Newman-Keuls as appropriate. Data are presented as mean+/-SD.

RESULTS

Exposure to hypoxia-reoxygenation increased neutrophil CD11b (94.33+/-40.65 vs. 34.32+/-6.83 mean channel fluorescence (MCF), P = 0.02), CD18 (109.84+/-35.44 vs. 59.05+/-6.71 MCF, P = 0.03) and endothelial ICAM-1 (146.62+/-16.78 vs. 47.29+/-9.85 MCF, P < 0.001) expression compared to normoxia. Neutrophil CD18 expression on exposure to hypoxia-reoxygenation was less in lidocaine (0.005 mg mL(-1)) treated cells compared to control (71.07+/-10.14 vs. 109.84+/-35.44 MCF, P = 0.03). Endothelial ICAM-1 expression on exposure to hypoxia-reoxygenation was less in lidocaine (0.005 mg mL(-1)) treated cells compared to control (133.25+/-16.05 vs. 146.62+/-16.78 MCF, P = 0.03). Hypoxia-reoxygenation increased HUVEC supernatant IL-1beta concentrations compared to normoxia (3.41+/-0.36 vs. 2.65+/-0.21 pg mL(-1), P = 0.02). Endothelial supernatant IL-1beta concentrations in lidocaine-treated HUVECs were similar to controls.

CONCLUSIONS

Lidocaine at clinically relevant concentrations decreased neutrophil CD18 and endothelial ICAM-1 expression but not endothelial IL-1beta concentrations.

The effect of aprotinin on hypoxia-reoxygenation-induced changes in neutrophil and endothelial function

BACKGROUND AND OBJECTIVE

An acute inflammatory response associated with cerebral ischaemia-reperfusion contributes to the development of brain injury. Aprotinin has potential, though unexplained, neuroprotective effects in patients undergoing cardiac surgery.

METHODS

Human neutrophil CD11 b/CD18, endothelial cell intercellular adhesion molecule-1 (ICAM-1) expression and endothelial interleukin (IL)-1beta supernatant concentrations in response to in vitro hypoxia-reoxygenation was studied in the presence or absence of aprotinin (1600 KIU mL(-1)). Adhesion molecule expression was quantified using flow cytometry and IL-1beta concentrations by enzyme-linked immunosorbent assay. Data were analysed using ANOVA and post hoc Student-Newman-Keuls test as appropriate.

RESULTS

Exposure to 60-min hypoxia increased neutrophil CD11b expression compared to normoxia (170+/-46% vs. 91+/-27%, P = 0.001) (percent intensity of fluorescence compared to time 0) (n = 8). Hypoxia (60 min) produced greater upregulation of CD11b expression in controls compared to aprotinin-treated neutrophils [(170+/-46% vs. 129+/-40%) (P = 0.04)] (n = 8). Hypoxia-reoxygenation increased endothelial cell ICAM-1 expression (155+/-3.7 vs. 43+/-21 mean channel fluorescence, P = 0.0003) and IL-1beta supernatant concentrations compared to normoxia (3.4+/-0.4 vs. 2.6+/-0.2, P = 0.02) (n = 3). Hypoxia-reoxygenation produced greater upregulation of ICAM- 1 expression [(155+/-3.3 vs. 116+/-0.7) (P = 0.001)] and IL-1beta supernatant concentrations [(3.4+/-0.3 vs. 2.6+/-0.1) (P = 0.01)] in controls compared to aprotinin-treated endothelial cell preparation (n = 3).

CONCLUSIONS

Hypoxia-reoxygenation-induced upregulation of neutrophil CD11b, endothelial cell ICAM-1 expression and IL-1beta concentrations is decreased by aprotinin at clinically relevant concentrations.

Effect of aprotinin on in vitro cerebral endothelial ICAM-1 expression induced by astrocyte-conditioned medium

BACKGROUND AND OBJECTIVE

Aprotinin administration may decrease the incidence of stroke associated with coronary artery bypass surgery by an unknown mechanism. Astrocytes exposed to hypoxia produce proinflammatory cytokines and upregulate intercellular adhesion molecule (ICAM)-1 on cerebral endothelium. This study investigated the effects of aprotinin on cerebral endothelial activation by hypoxic astrocytes in vitro.

METHODS

Mouse astrocytes were exposed to hypoxia in an anaerobic chamber for 4 h followed by reoxygenation for 24 h. Astrocyte-conditioned medium (ACM) collected from mouse astrocytes subjected to hypoxia/reoxygenation (HR) or normoxia were applied to mouse cerebral endothelial cell (MCEC) cultures for 4 and 24 h in normoxia. Endothelial cells were preincubated for 1 h with aprotinin (1600 KIU mL(-1)) prior to exposure to ACM. Flow cytometry was used to estimate endothelial ICAM-1 expression. Interleukin (IL)-1beta space concentrations in ACM were estimated with enzyme-linked immunosorbent assay (ELISA). Repeated comparisons were made using analysis of variance (ANOVA) and post hoc Tukey test as appropriate. P < 0.05 was considered significant. Data is presented as mean (standard deviation, SD).

RESULTS

MCEC ICAM-1 expression was greater after 24 h exposure to HR-ACM compared to normoxic-ACM (mean channel flouresence (MCF) 107.5 (4.5) vs. 74.3 (4.5), respectively, P < 0.001). ICAM-1 expression was decreased by aprotinin preincubation compared to control (MCF 91.0 (1.1) vs. 107.5 (2.1), P = 0.006). Supernatant IL-1beta concentrations in astrocytes exposed to HR were greater than those exposed to normoxia (7.1 (0.2) vs. 4.1 (0.2), P = 0.01).

CONCLUSIONS

This may be a neuroprotective mechanism associated with aprotinin administration.

The effect of clomethiazole on plasma concentrations of interleukin-6, -8, -1beta, tumor necrosis factor-alpha, and neutrophil adhesion molecule expression during experimental extracorporeal circulation

Clomethiazole (CMZ), a neuroprotective drug, has antiinflammatory actions. We investigated the effects of CMZ administration on plasma concentrations of interleukin (IL)-6, IL-8, IL-1beta, tumor necrosis factor-alpha, and neutrophil adhesion molecule expression during experimental extracorporeal circulation. Five healthy volunteers each donated 500 mL of blood, which was subsequently divided into equal portions. Identical extracorporeal circuits were simultaneously primed with donated blood (250 mL) and circulated for 2 h at 37 degrees C. CMZ was added to 1 of the circuits of each pair to achieve a total plasma concentration of 40 micro mol/L. Blood samples were withdrawn at (i) donation, (ii) immediately after addition of CMZ, and at (iii) 30, 60, 90, and 120 min after commencing circulation. Plasma concentrations of IL-6, IL-8, and tumor necrosis factor-alpha were less in the CMZ group compared with control after 60 min of circulation (2.2 [0.3] versus 3.2 [0.4], 14.9 [4.8] versus 21.9 [18.4], 63.3 [43.5] versus 132.2 [118.9] pg/mL, respectively, P < 0.05). After 120 min of circulation, neutrophils from CMZ-treated circuits showed significantly less CD18 expression compared with control (237.5 [97.4] versus 280.5 [111.5], P = 0.03). The addition of CMZ to experimental extracorporeal circuits decreases the inflammatory response. This effect may be of clinical benefit by decreasing inflammatory-mediated neurological injury during cardiopulmonary bypass.

IMPLICATIONS

Enhancement of gamma-aminobutyric acid(A)-mediated effects by clomethiazole (CMZ) and associated neuroprotection has been established in animal models of cerebral ischemia. In an ex vivo study, we demonstrated antiinflammatory activity of CMZ in experimental extracorporeal circulation. This represents a potential neuroprotective mechanism of CMZ in patients undergoing coronary artery bypass surgery.

How well tolerated are lipid-lowering drugs?

It has been clearly established that lipid-lowering treatments [such as 3-hydroxyl-3-methylglutamyl coenzyme A reductase inhibitors ('statins') or fibrates] can reduce cardiovascular events, and with one of the statins even total mortality, in high-risk populations. Intervention studies have not included the very old, but it is generally assumed that this patient group would benefit from these treatments to an extent similar to younger patients. Worries about the associations seen in observational studies between low cholesterol levels and cancer, cerebral haemorrhage or mood and behaviour change have been largely overcome by findings from the latest large drug intervention trials, which do not show any increase in these conditions with statin or fibrate treatments. The common adverse effects associated with these drugs are relatively mild and often transient in nature. Potentially more serious adverse effects, which are more clearly related to drug treatment and are probably dose-dependent, include elevations in hepatic transaminase levels and myopathy; however, these effects are uncommon and generally resolve rapidly when treatment is stopped. The risk of myopathy with fibrate treatment is increased in patients with renal impairment, and the risk of myopathy with statin treatment increases with co-administration of drugs that inhibit statin metabolism or transport. Other adverse effects are related to specific drugs, for example, clofibrate is associated with an increased risk of gallstones. Studies in elderly patients have not shown an increased risk of adverse effects with lipid-lowering drugs compared with younger patients, but in clinical practice there may be some increased risk, particularly with regards to drug interactions. Therefore, lipid-lowering drugs should be administered with extra caution to elderly patients.

Adolescents' perceptions of their parents' academic expectations: comparison of American, Chinese-American, and Chinese high school students

Cultural background not only influences family beliefs about the value of education, but may affect how academic expectations are communicated by parents and perceived by their children. This study examined differences in willingness to conform to parents' expectations of academic achievement as perceived by American, Chinese-American, and Chinese high school students. Findings indicated that Chinese students were more willing to accept their parents' advice and cared more about fulfilling academic expectations than did American students. Students in all three groups had similar feelings of independence. The views of Chinese-American students reflected the influence of both their Chinese heritage and the American culture in which they resided.

Differences between learning disability subtypes classified using the revised Woodcock-Johnson Psycho-Educational Battery

This study examined the characteristics of students with specific learning disabilities in either reading and spelling or arithmetic. Based on scores obtained using the revised Woodcock-Johnson Psycho-Educational Battery, students with a marked weakness in arithmetic relative to reading and spelling were designated as Group A. Group R-S showed the opposite pattern. Each group included 30 participants ranging in age from 7 to 16 years, with a mean age of 10 years. The boy-to-girl ratios were 16:14 and 19:11 in Group A and Group R-S, respectively. Comparisons using measures from the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) indicated that Group A was weaker in nonverbal skills than Group R-S, despite equivalent overall IQ scores between the two groups. Group R-S showed a within-group strength in nonverbal versus verbal skills. Group A students were more likely than Group R-S students to have counseling provided as part of their Individualized Education Program, suggesting greater socioemotional difficulty among Group A students. The present study supports the connection between nonverbal skills and socioemotional functioning noted by previous researchers, and generalizes findings from earlier studies to more current test editions.

Studies on the mutagenicity of mild gasification products of coal and their subfractions by the Salmonella/microsomal assay

Mild gasification of coal is a technology being developed in the United States in order to upgrade lower rank coals and facilitate their use in coal-burning electric generation plants. Thirteen coal-derived mild gasification products from different coal sources and processing conditions have been examined for their potential biohazards. The mutagenicity of these samples was tested with the Ames Salmonella/microsomal assay. Two solvents, dimethyl sulfoxide (DMSO) and polyoxyethylene-sorbitan monooleate (Tween 80), were used to dissolve samples in a manner to facilitate their interaction with the test organisms. The results showed that 9 of the 13 samples displayed mutagenic activity in test strains TA98 and/or TA100 with or without metabolic activation, whether dissolved in Tween 80 or DMSO. Five mutagenic and two nonmutagenic samples were class-fractionated into basic, acidic, nonpolar, and polar neutral subfractions to examine their class-related mutagenic activities. Results of the testing of subfractions of the five mutagenic and one nonmutagenic samples showed mutagenic activity in at least the nonpolar neutral fraction. The subfractions of the another nonmutagenic sample did not display any mutagenic activity. Chemical characterization of the subfractions revealed the existence of aromatic hydrocarbons in certain subfractions, which may be responsible for the mutagenic activity of the coal-derived mild gasification products.

Mutagenicity of mild gasification products in Salmonella typhimurium

Mild gasification is a coal-conversion technology that is currently under development in order to help meet future energy needs. 7 products from this process were assayed for mutagenic activity in the pre-incubation variant of the Salmonella assay (Ames test) using both DMSO and Tween 80 as sample solvents. Significant mutagenic activity was detected only in the wide-boiling-point composite materials, and the amount of this activity was found to be dependent on the solvent utilized. The highest number of revertants detected were on TA98 and its O-acetyltransferase over-producing derivative, YG1024, in the presence of the S9 microsomal fraction. Aromatic amines were suggested as a possible source of the mutagenic activity elicited. An examination of the liquid and tar phases of one composite material (MG-120) indicated that the mutagenic activity was restricted to the tar phase.

Energetics of folding subtilisin BPN'

Subtilisin is an unusual example of a monomeric protein with a substantial kinetic barrier to folding and unfolding. Here we document for the first time the in vitro folding of the mature form of subtilisin. Subtilisin was modified by site-directed mutagenesis to be proteolytically inactive, allowing the impediments to folding to be systematically examined. First, the thermodynamics and kinetics of calcium binding to the high-affinity calcium A-site have been measured by microcalorimetry and fluorescence spectroscopy. Binding is an enthalpically driven process with an association constant (Ka) equal to 7 x 10(6) M-1. Furthermore, the kinetic barrier to calcium removal from the A-site (23 kcal/mol) is substantially larger than the standard free energy of binding (9.3 kcal/mol). The kinetics of calcium dissociation from subtilisin (e.g., in excess EDTA) are accordingly very slow (t1/2 = 1.3 h at 25 degrees C). Second, to measure the kinetics of subtilisin folding independent of calcium binding, the high-affinity calcium binding site was deleted from the protein. At low ionic strength (I = 0.01) refolding of this mutant requires several days. The folding rate is accelerated almost 100-fold by a 10-fold increase in ionic strength, indicating that part of the free energy of activation may be electrostatic. At relatively high ionic strength (I = 0.5) refolding of the mutant subtilisin is complete in less than 1 h at 25 degrees C. We suggest that part of the electrostatic contribution to the activation free energy for folding subtilisin is related to the highly charged region of the protein comprising the weak ion binding site (site B).(ABSTRACT TRUNCATED AT 250 WORDS)