Highly Efficient Coremoval of Nitrate and Phosphate Driven by a Sulfur-Siderite Composite Reactive Filler toward Secondary Effluent Polishing

Reactive fillers consisting of reduced sulfur and iron species (SFe-ReFs) have received increasing attention in tertiary wastewater treatment for nitrate and phosphate coremoval. However, the existing SFe-ReFs suffer from either low performance (e.g., pyrrhotite and pyrite) or unsatisfactory use in terms of combustible risk and residual nonreactive impurities (e.g., sulfur mixing with natural iron ores). Here, we developed a new type of sulfur-siderite composite ReF (SSCReF) with a structure of natural siderite powders eventually embedded into sulfur. SSCReFs exhibited many excellent properties, including higher mechanical strengths and hardness and especially much poorer ignitability compared to pure sulfur. By using SSCReF to construct packed-bed reactors, the highest denitrification and dephosphorization rates reached 829.70 gN/m3/d (25 wt % siderite) and 36.70 gP/m3/d (75 wt % siderite), respectively. Dephosphorization was demonstrated to be dependent on sulfur-driven denitrification, in which the acid produced from the later process promoted Fe(II) dissolution, which then directly combined with phosphate to form vivianite or further converted into phosphate adsorbents (ferrihydrite, a green rust-like compound). Water flush was an effective way to finally wash out these surface deposited Fe-P compounds, as well as those nonreactive impurities (Si and Al-bearing compounds) detached from SSCReF. Such a highly efficient and safe SSCReF holds considerable application potential in secondary effluent polishing.

[Comparison of the predictive value of Padua and the IMPEDE assessment scores for venous thromboembolism in patients with newly diagnosed multiple myeloma: A single institution experience]

Objective: To compare the predictive efficacy of the two thrombosis risk assessment scores (Padua and IMPEDE scores) in venous thromboembolism (VTE) within 6 months in patients with newly diagnosed multiple myeloma (NDMM) in China. Methods: This study reviewed the clinical data of 421 patients with NDMM hospitalized in Beijing Jishuitan Hospital from April 2014 to February 2022. The sensitivity, specificity, accuracy, and Youden index of the two scores were calculated to quantify the thrombus risk assessment of VTE by the Padua and IMPEDE scores. The receiver operating characteristics curves of the two evaluation scores were drawn. Results: The incidence of VTE was 14.73%. The sensitivity, specificity, accuracy, and Youden index of the Padua score were 100%, 0%, 14.7%, and 0% and that of the IMPEDE score was 79%, 44%, 49.2%, and 23%, respectively. The areas under the curve of Padua and IMPEDE risk assessment scores were 0.591 and 0.722, respectively. Conclusion: IMPEDE score is suitable for predicting VTE within 6 months in patients with NDMM.

COVID-19 pandemic and neonatal birth weight: a systematic review and meta-analysis

OBJECTIVES

Lockdown was implemented in many countries during the pandemic, which led to myriad changes in pregnant women's lives. However, the potential impacts of the COVID-19 pandemic on neonatal outcomes remain unclear. We aimed to evaluate the association between the pandemic and neonatal birth weight.

STUDY DESIGN

This was a systematic review and meta-analysis of the previous literature.

METHODS

We searched the MEDLINE and Embase databases up to May 2022 and extracted 36 eligible studies that compared neonatal birth weight between the pandemic and the prepandemic period. The following outcomes were included: mean birth weight, low birth weight (LBW), very low birth weight (VLBW), macrosomia, small for gestational age (SGA), very small for gestational age (VSGA), and large for gestational age (LGA). Statistical heterogeneity among studies was assessed to determine whether a random effects model or fixed effects model was conducted.

RESULTS

Of the 4514 studies identified, 36 articles were eligible for inclusion. A total of 1,883,936 neonates during the pandemic and 4,667,133 neonates during the prepandemic were reported. We identified a significant increase in mean birth weight (pooled mean difference [95% confidence interval (CI)] = 15.06 [10.36, 19.76], I² = 0.0%, 12 studies) and a reduction in VLBW (pooled OR [95% CI] = 0.86 [0.77, 0.97], I² = 55.4%, 12 studies). No overall effect was identified for other outcomes: LBW, macrosomia, SGA, VSGA, and LGA. There was publication bias for mean birth weight with a borderline significance (Egger's P = 0.050).

CONCLUSION

Pooled results showed the pandemic was significantly associated with an increase in mean birth weight and a reduction in VLBW, but not for other outcomes. This review provided clues about the indirect effects of the pandemic on neonatal birth weight and more healthcare measures needed to improve neonatal long-term health.

Prognostic impact of lymph node harvest for patients with node-negative esophageal squamous cell carcinoma: a large-scale multicenter study

Background

We examined the association between the number of resected lymph nodes and survival to determine the optimal lymphadenectomy for thoracic esophageal squamous cell carcinoma (ESCC) patients with negative lymph node.

Methods

We included 1,836 patients from Chinese three high-volumed hospitals with corresponding clinicopathological characters such as gender, age, tumor location, tumor grade and TNM stage of patients. The median follow-up of included patients was 45.7 months (range, 1.03-117.3 months). X-Tile plot was used to identify the lowest number of lymphadenectomy. The multivariate model's construction was in use of parameters with clinical significance for survival and a nomogram based on clinical variable with P<0.05 in Cox regression analysis. Both two models were validated using a cohort extracted from the Surveillance, Epidemiology, and End Results (SEER) 18 registries database between 1975 and 2016 (n=951).

Results

More lymphadenectomy numbers were significantly associated with better survival in patients both in training cohort [hazard ratio (HR) =0.980; 95% confidence interval (CI): 0.971-0.988; P<0.001] and validation cohort (HR =0.980; 95% CI: 0.968-0.991; P=0.001). Cut-off point analysis determined the lowest number of 9 for thoracic ESCC patients in N0 stage through training cohort (C-index: 0.623; sensitivity: 80.7%; 1 - specificity: 72.5%) when compared with 10 in validation cohort (C-index: 0.643; sensitivity: 78.2%; 1 - specificity: 63.0%). The cut-off points of 9 were examined in training cohort and validated in the divided cohort from validation cohort (all P<0.05). Meanwhile, nomograms for both cohorts were constructed and the calibration curves for both cohorts agreed well with the actual observations in terms of predicting 3- and 5-year survival, respectively.

Conclusions

Larger number for lymphadenectomy was associated with better survival in thoracic ESCC patients in N0 stage. Nine was what we got as the lowest number for lymphadenectomy in pN0 ESCC patients through this study, and our result should be confirmed further.

Prognostic Role of Nodal Skip Metastasis in Thoracic Esophageal Squamous Cell Carcinoma: A Large-Scale Multicenter Study

BACKGROUND

Nodal-skip metastasis (NSM) is found in esophageal squamous cell carcinoma (ESCC), but its prognostic role is controversial. This study aimed to investigate the prognostic value of NSM for thoracic ESCC patients.

METHODS

Categorization of NSM was according to the N groupings of Japan Esophagus Society (JES) staging system, which is dependent on tumor location. Using the Kaplan-Meier method and Cox-regression analysis, this study retrospectively analyzed the overall survival (OS) for 2325 ESCC patients after radical esophagectomy at three high-volume esophageal cancer centers. Predictive models also were constructed.

RESULTS

The overall NSM rate was 20% (229/1141): 37.4% in the in upper, 12.9% in the middle, and 22.2% in the lower thoracic ESCC. The patients with NSM always had a better prognosis than those without NSM. Furthermore, NSM was an independent prognostic factor for thoracic ESCC patients (hazard ratio [HR], 0.633; 95% confidence interval [CI], 0.499-0.803; P < 0.001). By integrating the prognostic values of NSM and N stage, the authors proposed the new N staging system. The categories defined by the new N staging system were more homogeneous in terms of OS than those defined by the current N system. Moreover, the new N system was shown to be an independent prognostic factor also for thoracic ESCC patients (HR, 1.607; 95% CI, 1.520-1.700; P < 0.001). Overall, the new N system had slightly better homogeneity, discriminatory ability, and monotonicity of gradient than the current N system.

CONCLUSIONS

This study emphasized the prognostic power of NSM and developed a modified node-staging system to improve the efficiency of the current International Union for Cancer Control (UICC)/American Joint Committee on Cancer (AJCC) N staging system.

The outcomes of post-traumatic arthritis vs osteoarthritis following primary total knee arthroplasty: A protocol of matched cohort study

BACKGROUND

Total knee arthroplasty (TKA) for treatment of end-stage post-traumatic arthritis (PTA) has specific technical difficulties and complications. The aim of this study was to examine the outcome of TKA after PTA and to compare it with a cohort osteoarthritis (OA).

METHODS

A retrospective review of patients undergoing primary TKA at a single university hospital from 2013 to 2016 was performed. A minimum follow-up of 4 years was required. Patients in the study group were matched 1:2 with patients in the cohort group based on the following criteria: age at time of TKA (±3 years), body mass index (±3 points), sex, and American Society of Anesthesiologists score (±1 point). Outcome measures included surgical time, intraoperative complications, Oxford Knee Score, range of motion, postoperative complications, and revision.

RESULTS

This clinical trial is expected to determine whether PTA is associated with increased risks of complications and revision or reduced functional outcomes following TKA.

TRIAL REGISTRATION

This study protocol was registered in Research Registry (researchregistry5455).

Curcumin Inhibits Proliferation of Synovial Cells by Downregulating Expression of Matrix Metalloproteinase-3 in Osteoarthritis

Objective

To investigate the association between curcumin and the differentially expressed genes (DEG) in synovial tissues of osteoarthritis.

Methods

Microarray analysis was used to screen for the DEG in osteoarthritis synovial cells. Curcumin‐related genes were identified through the drug–gene interaction network STITCH (http://stitch.embl.de/cgi/input.pl). Expression levels of fibronectin 1 (FN1) and collagen III protein were measured by western blot. MTT assay was used to examine the effects of different concentrations of curcumin on cell viability. Western blot and quantitative real‐time polymerase chain reaction were used to validate the different expression levels of matrix metalloproteinase‐3 (MMP3). Clone formation assay, flow cytometry, and the TUNEL method were conducted for detecting the cell proliferation and apoptosis rate.

Results

In the two chips of GSE1919 and GSE55235, the average expression of MMP3 in the osteoarthritis group was 63.7% and 12.9% higher than that of the healthy control, respectively. The results of western blot also showed that the average expression of MMP3 in 30 osteoarthritis patients was 132% higher than that of the healthy group, which confirmed that MMP3 was highly expressed in osteoarthritis group. The results of MTT showed that at 72 h, the cell viability of 40 μmol/L curcumin was the lowest and 79.6% lower than for the 0 μmol/L group, so the final curcumin concentration of 40 μmol/L was selected for subsequent experiments. Western blot results further showed that the expression of MMP3 was 44% lower in the untreated groups compared with the curcumin group, and the expressions of FN1 and collagen III were increased by 112% and 84%, respectively, which indicated that curcumin inhibited MMP3 expression and decreased osteoarthritis synovial cell activity. Cloning formation experiments showed that cell numbers increased by 75% and 20.5% in untreated and curcumin groups, and compared with the untreated group, the cells in the curcumin group decreased by 30.8%. Flow cytometry showed that the apoptotic rate in the curcumin group increased by 85.1% compared with the untreated group, but for a single group, MMP3 decreased the apoptotic rate by 53.9% and 46.7%, respectively.

Conclusions

MMP3 was highly expressed in osteoarthritis synovial cells. Curcumin could reduce cell viability, inhibit cell proliferation, increase cell apoptosis, and eventually alleviate inflammation of osteoarthritis by inhibiting the expression of MMP3.

Functional and proteomic comparison of different techniques to produce equine anti-tetanus immunoglobulin F(ab')2 fragments

Tetanus is still a major cause of human deaths in several developing countries. In particular, the neonatal form remains a significant public health problem. According to the World Health Organization, administration of tetanus toxoid is recommended for neonatal tetanus patients. Furthermore, tetanus antitoxin or anti-tetanus immunoglobulin (Ig) are used for mild case or intensive care. This paper discusses a novel purification technique for improving equine anti-tetanus Ig production. First, equine plasma dealt with two steps salting out with ammonium sulfate; second, ultrafiltration concentration liquid purified by one successive protein G based affinity chromatography steps; finally, the purified F(ab')2 fragments was characterized using biochemical and proteomic methods and shown to be pure and homogeneous. Compared with the original technique product, specific activity increased by 80% (about 90,000 IU/g) and recovery of F(ab')2 is approximately equal 75%. Furthermore, Proteomic profiling of total technique process is demonstrated by nano-HPLC-MS and bioinformatics analysis. New technique to produce equine anti-tetanus immunoglobulin F(ab')2 fragments from crude plasma in high quality and yield. And it also could be used for industrial amplification.

Cupping therapy for treating knee osteoarthritis: The evidence from systematic review and meta-analysis

OBJECTIVE

Cupping therapy is widely used in East Asia, the Middle East, or Central and North Europe to manage the symptom of knee osteoarthritis (KOA). The purpose of this systematic review was to evaluate the available evidence from randomized controlled trials (RCTs) of cupping therapy for treating patients with KOA.

METHODS

The following databases were searched from their inception until January 2017: PubMed, Embase, the Cochrane Central Register of Controlled Trials and four Chinese databases [WanFang Med Database, Chinese BioMedical Database, Chinese WeiPu Database, and China National Knowledge Infrastructure (CNKI)]. Only the RCTs related to the effects of cupping therapy on KOA were included in this systematic review. A quantitative synthesis of RCTs will be conducted using RevMan 5.3 software. Study selection, data extraction, and validation was performed independently by two reviewers. Cochrane criteria for risk-of-bias were used to assess the methodological quality of the trials.

RESULTS

Seven RCTs met the inclusion criteria, and most were of low methodological quality. Study participants in the dry cupping therapy plus the Western medicine therapy group showed significantly greater improvements in the pain [MD = -1.01, 95%CI (-1.61, -0.41), p < 0.01], stiffness [MD = -0.81, 95%CI (-1.14, -0.48), p < 0.01] and physical function [MD = -5.53, 95%CI (-8.58, -2.47), p < 0.01] domains of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) compared to participants in the Western medicine therapy group, with low heterogeneity (Chi² = 0.00 p = 1.00, I² = 0% in pain; Chi² = 0.45 p = 0.50, I² = 0% in stiffness; Chi² = 1.09 p = 0.30, I² = 9% in physical function). However, it failed to do so on a Visual Analog Scale (VAS) [MD = -0.32, 95%CI (-0.70, 0.05), p = 0.09]. In addition, when compared with Western medicine therapy alone, meta-analysis of four RCTs suggested favorable statistically significant effects of wet cupping therapy plus western medicine on response rate [MD = 1.06, 95%CI (1.01, 1.12), p = 0.03; heterogeneity: Chi² = 1.13, p = 0.77, I² = 0%] and Lequesne Algofunctional Index (LAI) [MD = -2.74, 95%CI (-3.41, -2.07), p < 0.01; heterogeneity: Chi² = 2.03, p = 0.57, I² = 0% ].

CONCLUSION

Only weak evidence can support the hypothesis that cupping therapy can effectively improve the treatment efficacy and physical function in patients with KOA.

Low EphA7 Expression Correlated with Lymph Node Metastasis and Poor Prognosis of Patients with Esophageal Squamous Cell Carcinoma

As a member of the Eph family of receptor tyrosine kinases, EphA7 plays an important role in cancer. However, the expression and significance of Eph receptors in esophageal squamous cell carcinoma (ESCC) remain unclear. Here, we detected the expression of EphA7 by immunohistochemistry in a sample of 352 patients with ESCC, and aimed to investigate the expression status of EphA7 in ESCC and its impact on prognosis. The results showed that low EphA7 expression significantly correlated with lymph node metastases (N0: 29%; N1: 64%. p<0.001), poor degree of tumor differentiation (G1: 31%; G2: 49%; G3: 58%. p=0.009) and pTNM staging (I+II: 33%; III+IV: 58%. p<0.001). Furthermore, in a combined analysis, patients with low EphA7-expressing tumors showed a shorter overall survival than those with high expression, resulting in a five-year overall survival rate of 47.4% vs. 52.6%, respectively (p=0.016). Consequently, patients with a low EphA7 expression have poorer prognosis in ESCC compared with those manifesting high expression.

Effects of TGF-β1 and alginate on the differentiation of rabbit bone marrow-derived mesenchymal stem cells into a chondrocyte cell lineage

The aim of the present study was to investigate the effect of a three-dimensional (3D) culture system of sodium alginate gel on the directional differentiation induction of bone marrow-derived mesenchymal stem cells (BMSCs) into chondrocytes, as well as the in vitro gene transfection technique. The biological characteristics of the passage and proliferation of rabbit BMSCs were investigated under conditions of in vitro monolayer and 3D culture of sodium alginate gel. Transforming growth factor (TGF)-β1 gene recombinant adenoviral cosmid vectors and the recombinant adenoviral vector Ad.TGF-β1 were constructed, and the effect of Ad.TGF-β1 transfection on the differentiation of BMSCs into chondrocytes was investigated. The whole bone marrow rinsing method was used to obtain, separate and purify the rabbit BMSCs, and the in vitro monolayer and 3D culture of sodium alginate gel were thus successfully and stably established. A safe, stable and efficient method of constructing Ad.TGF-β1 TGF-β1 gene recombinant adenoviral vectors was established. Following TGF-β1 transfection, BMSCs were able to continuously secrete significantly increased amounts of specific extracellular matrix components of chondrocytes, such as collagen II and proteoglycans. Furthermore, the effects in the post-gene transfection 3D culture group were found to be enhanced compared with those in the monolayer culture group. In conclusion, the 3D culture system of sodium alginate gel and in vitro gene transfection exhibited significant inductive effects on differentiation, which could be used to promote BMSCs to differentiate into chondrocytes.

Single-stage posterior vertebral column resection and internal fixation for old fracture-dislocations of thoracolumbar spine: a case series and systematic review

PURPOSE

To evaluate the efficacy of single-stage posterior vertebral column resection for old thoracolumbar fracture-dislocations with spinal cord injury.

METHODS

From January 2007 to June 2013, twelve male patients (average age, 32.6 years; range 19-57 years) with old fracture-dislocations of the thoracolumbar spine and spinal cord injury underwent single-stage posterior vertebral column resection and internal fixation. All patients were assessed for relief of the pain and restoration of neurologic function. Postoperative Cobb angle was measured and bone graft fusion was evaluated by X-ray. A systematic review of 25 studies evaluating surgical management of thoracolumbar fractures with spinal cord injuries was also performed.

RESULTS

From our case series, six of the nine patients with Frankel grade A had significant improvement in urination and defecation after surgery. The three patients with Frankel grades B and C had progression of 1-2 grades after surgery. Bony fusion was achieved and local back pain was relieved in all patients after surgery. From our systematic review of 25 studies, the majority of patients had improved back pain, the postoperative kyphotic angle was significantly reduced compared with pre-operative kyphotic angle.

CONCLUSION

Single-stage posterior vertebral column resection and internal fixation for old thoracolumbar fracture-dislocations is an ideal treatment allowing for thorough decompression, relief of pain, correction of deformities, and restoration of spinal stability.

LEVEL OF EVIDENCE

IV.

The prognostic implications of microvascular density and lymphatic vessel density in esophageal squamous cell carcinoma: Comparative analysis between the traditional whole sections and the tissue microarray

Focal distribution of microvascular and lymphatic vessels is a critical issue in cancer, and is measured by tissue microarray (TMA) construction from paraffin-embedded surgically obtained tissues, a process that may not accurately reflect true focal distribution. The aim of this study was to assess the concordance of microvascular density (MVD) and lymphatic vessel density (LVD) in TMAs with corresponding whole sections, and to correlate the MVD or LVD with clinicopathological parameters in 124 cases of esophageal squamous cell carcinoma (ESCC). MVD, determined by CD105 immunohistochemistry of whole sections, was strongly associated with lymph node metastasis (p=0.000) and pTNM stage (p=0.001). Kaplan-Meier survival analysis showed that increasing CD105 microvessel count correlated with decreasing survival (p<0.001). The same result was acquired when MVD was calculated from tissue microarrays. Analysis of continuous data showed a highly significant correlation between whole sections and TMA data (Pearson r=0.522, p<0.001). Increasing LVD, as determined by D2-40 immunohistochemistry of whole sections, correlated with decreasing survival, but this relationship was undetectable using TMAs. In conclusion, we demonstrate that for the selected endothelial markers, TMAs can provide a realistic and reliable estimate of the extent of MVD, but not LVD in ESCC samples.

Conditional survival in patients treated with vascular endothelial growth factor-targeted therapy for advanced renal cell carcinoma

PURPOSE

Conditional survival (CS) offers more relevant prognostic information for patients once they have survived for some time. The objective of this study was to determine the CS for advanced renal cell carcinoma (RCC) patients treated with vascular endothelial growth factor-targeted therapy.

METHODS

A total of 345 patients treated between 2006 and 2011 fulfilled the inclusion criteria and were reviewed for analyses. The 1-year conditional and actual survival rates were calculated for survivors from treatment to month 24. Subgroup-specific CS rates were generated after adjustment of the covariate influence. The Cox proportional hazard models were used to assess the prognostic factors at baseline and 1-year landmark.

RESULTS

The probabilities of surviving an additional year given survival to 6, 12, 18, and 24 months were 72.2, 76.3, 78.2, and 78.6 %, respectively. Remarkable increase in CS was observed in patients initially classified as intermediate or poor risk according to Heng risk groups. For patients survived 24 months after treatment, the adjusted CS for the following year was over 80 % regardless of initial risk attribution. Compared to baseline analysis, Heng risk groups were less predictive of survivorship after surviving 1 year. The addition of disease control status to multifactorial model significantly improved survival estimation for 1-year survivors (p < 0.01).

CONCLUSIONS

CS provides useful information regarding life expectancy for survivors of advanced RCC treated with targeted therapy. Furthermore, disease control status within a specific period of time is critical to the prediction of subsequent survival.

[Common and variant peak ratios in IR fingerprint of Cacumen platycladi with dual-index sequence analysis]

To establish a new method to analyze IR fingerprint, which is in line with the characteristic of traditional Chinese medicine, two indexes, common peak ratio and variant peak ratio, were applied and their values were calculated by means of sequential analysis, in which each Cacumen platycladi sample's IR fingerprint spectra were set up and the common peak ratio sequences were arranged in the order of size in comparison with other samples. The analytical results showed that samples G1 and G8 from the same region, and G4, G2 and G6 from the closer regions were the most similar samples with higher common peak ratio (> or = 90.0%) and lower variant peak ratio (< or = 11.1%). However, the samples G10, G3, G4 and G5 from the closer regions collected in different years, and G2 and G7 from the farther regions,were of significant disparity with common peak ratio less than 50% and variant peak ratio larger than 50%. As a result, the method could be used to distinguish Cacumen platycladi of different areas and batches. The dual index sequential analysis enables us to distinguish two or more herb's IR fingerprints, is a new method to analyze IR fingerprint spectra, and can be used in line with the characteristics of traditional Chinese medicine.

First principle study of hydrogenation of MgB2: an important step toward reversible hydrogen storage in the coupled LiBH4/MgH2 system

Recent experiments [F. E. Pinkerton, M. S. Meyer, G. P. Meisner, M. P. Balogh, and J. J. Vajo, J. Phys. Chem. C 111, 12881 (2007) and J. J. Vajo and G. L. Olson, Scripta Mater. 56, 829 (2007)] demonstrated that the recycling of hydrogen in the coupled LiBH4/MgH2 system is fully reversible. The rehydrogenation of MgB2 is an important step toward the reversibility. By using ab initio density functional theory calculations, we found that the activation barrier for the dissociation of H2 are 0.49 and 0.58 eV for the B and Mg-terminated MgB2(0001) surface, respectively. This implies that the dissociation kinetics of H2 on a MgB2(0001) surface should be greatly improved compared to that in pure Mg materials. Additionally, the diffusion of dissociated H atom on the Mg-terminated MgB2(0001) surface is almost barrier-less. Our results shed light on the experimentally-observed reversibility and improved kinetics for the coupled LiBH4/MgH2 system.

Hydrogen Spillover Mechanism on a Pd-Doped Mg Surface as Revealed by ab initio Density Functional Calculation

The hydrogenation kinetics of Mg is slow, impeding its application for mobile hydrogen storage. We demonstrate by ab initio density functional theory (DFT) calculations that the reaction path can be greatly modified by adding transition metal catalysts. Contrasting with Ti doping, a Pd dopant will result in a very small activation barrier for both dissociation of molecular hydrogen and diffusion of atomic H on the Mg surface. This new computational finding supports-for the first time by ab initio simulation-the proposed hydrogen spillover mechanism for rationalizing experimentally observed fast hydrogenation kinetics for Pd-capped Mg materials.

First-Principle Study of Adsorption of Hydrogen on Ti-Doped Mg(0001) Surface

Ab initio density functional theory (DFT) calculations are performed to study the adsorption of H2 molecules on a Ti-doped Mg(0001) surface. We find that two hydrogen molecules are able to dissociate on top of the Ti atom with very small activation barriers (0.103 and 0.145 eV for the first and second H2 molecules, respectively). Additionally, a molecular adsorption state of H2 above the Ti atom is observed for the first time and is attributed to the polarization of the H2 molecule by the Ti cation. Our results parallel recent findings for H2 adsorption on Ti-doped carbon nanotubes or fullerenes. They provide new insight into the preliminary stages of hydrogen adsorption onto Ti-incorporated Mg surfaces.

Catalytic Effects of Subsurface Carbon in the Chemisorption of Hydrogen on a Mg(0001) Surface: an Ab-initio Study

Ab initio density functional theory (DFT) calculations are performed to explore possible catalytic effects on the dissociative chemisorption of hydrogen on a Mg(0001) surface when carbon is incorporated into Mg materials. The computational results imply that a C atom located initially on a Mg(0001) surface can migrate into the subsurface and occupy an fcc interstitial site, with charge transfer to the C atom from neighboring Mg atoms. The effect of subsurface C on the dissociation of H2 on the Mg(0001) surface is found to be relatively marginal: a perfect sublayer of interstitial C is calculated to lower the barrier by 0.16 eV compared with that on a pure Mg(0001) surface. Further calculations reveal, however, that sublayer C may have a significant effect in enhancing the diffusion of atomic hydrogen into the sublayers through fcc channels. This contributes new physical understanding toward rationalizing the experimentally observed improvement in absorption kinetics of H2 when graphite or single walled carbon nanotubes (SWCNT) are introduced into the Mg powder during ball milling.

The Role of Ti as a Catalyst for the Dissociation of Hydrogen on a Mg(0001) Surface

In this paper, the dissociative chemisorption of hydrogen on both pure and Ti-incorporated Mg(0001) surfaces are studied by ab initio density functional theory (DFT) calculations. The calculated dissociation barrier of hydrogen molecule on a pure Mg(0001) surface (1.05 eV) is in good agreement with comparable theoretical studies. For the Ti-incorporated Mg(0001) surface, the activated barrier decreases to 0.103 eV due to the strong interaction between the molecular orbital of hydrogen and the d metal state of Ti. This could explain the experimentally observed improvement in absorption kinetics of hydrogen when transition metals have been introduced into the magnesium materials.

Effects of DNA structure and homology length on vaccinia virus recombination

Replicating poxviruses catalyze high-frequency recombination reactions by a process that is not well understood. Using transfected DNA substrates we show that these viruses probably use a single-strand annealing recombination mechanism. Plasmids carrying overlapping portions of a luciferase gene expression cassette and luciferase assays were first shown to provide an accurate method of assaying recombinant frequencies. We then transfected pairs of DNAs into virus-infected cells and monitored the efficiencies of linear-by-linear, linear-by-circle, and circle-by-circle recombination. These experiments showed that vaccinia virus recombination systems preferentially catalyze linear-by-linear reactions much more efficiently than circle-by-circle reactions and catalyze circle-by-circle reactions more efficiently than linear-by-circle reactions. Reactions involving linear substrates required surprisingly little sequence identity, with only 16-bp overlaps still permitting approximately 4% recombinant production. Masking the homologies by adding unrelated DNA sequences to the ends of linear substrates inhibited recombination in a manner dependent upon the number of added sequences. Circular molecules were also recombined by replicating viruses but at frequencies 15- to 50-fold lower than are linear substrates. These results are consistent with mechanisms in which exonuclease or helicase processing of DNA ends permits the forming of recombinants through annealing of complementary single strands. Our data are not consistent with a model involving strand invasion reactions, because such reactions should favor mixtures of linear and circular substrates. We also noted that many of the reaction features seen in vivo were reproduced in a simple in vitro reaction requiring only purified vaccinia virus DNA polymerase, single-strand DNA binding protein, and pairs of linear substrates. The 3'-to-5' exonuclease activity of poxviral DNA polymerases potentially catalyzes recombination in vivo.

Recombination during early herpes simplex virus type 1 infection is mediated by cellular proteins

Homologous recombination was examined in cells infected with herpes simplex virus type I. Circular and linear DNA with directly repeated sequences was introduced as recombination substrates into cells. Recombination was measured either by origin-dependent amplification of recombination products or by recombination-dependent expression of luciferase from a disrupted gene. Homologous recombination in baby hamster kidney cells converted linear DNA to circular templates for DNA replication and luciferase expression in the complete absence of virus. The products of homologous recombination were efficiently amplified by the viral replication apparatus. The efficiency of recombination was dependent on the structure of the substrate as well as the cell type. Linear DNA with the direct repeats at internal positions failed to recombine in Balb/c 3T3 cells and induced p53-dependent apoptosis. In contrast, linear DNA with directly repeated sequences precisely at the ends recombined and replicated in 3T3 cells. Homologous recombination in baby hamster kidney cells did not depend on the position of the repeated sequences. We conclude that homologous recombination is independent of viral gene functions and that it is likely to be carried out by cellular proteins. We suggest that homologous recombination between directly repeated sequences in the linear herpes simplex virus type 1 chromosome may help to avoid p53-dependent apoptosis and to promote viral DNA replication.

In vitro concatemer formation catalyzed by vaccinia virus DNA polymerase

During poxvirus infection, both viral genomes and transfected DNAs are converted into high-molecular-weight concatemers by the replicative machinery. However, aside from the fact that concatemer formation coincides with viral replication, the mechanism and protein(s) catalyzing the reaction are unknown. Here we show that vaccinia virus DNA polymerase can catalyze single-stranded annealing reactions in vitro, converting linear duplex substrates into linear or circular concatemers, in a manner directed by sequences located at the DNA ends. The reaction required > or =12 bp of shared sequence and was stimulated by vaccinia single-stranded DNA-binding protein (gpI3L). Varying the structures at the cleaved ends of the molecules had no effect on efficiency. These duplex-joining reactions are dependent on nucleolytic processing of the molecules by the 3'-to-5' proofreading exonuclease, as judged by the fact that only a 5'-(32)P-end label is retained in the joint molecules and the reaction is inhibited by dNTPs. The resulting concatemers are joined only through noncovalent bonds, but can be processed into stable molecules in E. coli, if the homologies permit formation of circular molecules. This reaction provides a starting point for investigating the mechanism of viral concatemer formation and can be used to clone PCR-amplified DNA.

Negative correlation between cyclophilin mRNA level in leukocytes of renal allograft recipients and ciclosporin concentration in whole blood

AIM

To study mRNA level of cyclophilin in the white blood cells (WBC) of the renal allograft recipients (RAR) and its correlation with ciclosporin concentration in whole blood.

METHODS

The cyclophilin mRNA levels and beta-actin as controls in the WBC of 47 RAR were measured by quantitative reverse transcription polymerase chain reaction. The blood ciclosporin assay utilized monoclonal antibody fluorescence polarization immunoassay.

RESULTS

With the increase of ciclosporin concentration in whole blood (from 62 micrograms.L-1 to 678 micrograms.L-1), relative cyclophilin mRNA level in the WBC of RAR decreased nonlinearly (from 1.1 to 0.03, r = 0.8195).

CONCLUSION

There was a negative correlation between the mRNA level of cyclophilin in the WBC of RAR and the ciclosporin concentration in whole blood.

Direct repeats of the herpes simplex virus a sequence promote nonconservative homologous recombination that is not dependent on XPF/ERCC4

We have examined mechanisms of recombination in mammalian cells infected with herpes simplex virus type 1 (HSV-1). Amplification of plasmids containing a viral origin of replication, oriS, in cells superinfected with HSV-1 revealed that linear DNA could be efficiently converted to templates for replication. Two distinct pathways were observed: imprecise end joining and nonconservative homologous recombination. We noted that direct repeats of the viral a sequence promoted efficient nonconservative homologous recombination in BHK cells as well as human repair-proficient 1BR.3N cells and xeroderma pigmentosum group F (XP-F) cells. The reaction gave rise to functional a sequences supporting the formation of defective viruses. It did not seem to proceed by single-strand annealing since it occurred in the absence of XPF/ERCC4, the mammalian homolog of the Rad1 endonuclease from Saccharomyces cerevisiae. In contrast, direct repeats of a 161-bp nonviral sequence did not take part in nonconservative homologous recombination in XP-F cells. Our results suggest that homologous recombination may be involved in the circularization of viral genomes. Furthermore, they demonstrate that amplification of recombination products supported by HSV-1 allows a direct examination of pathways for double-strand-break repair in human cells.

A new approach to the treatment of malignant effusion

Lymphocytes isolated from malignant effusion were induced to become LAK cells after in vitro culture with rIL-2. 28 patients with malignant effusion were treated by i.p. or intrapleural administration of autologous LAK cells combined with rIL-2 or by rIL-2 alone. The effusion disappeared in 13 patients and significantly decreased in another 13. Two patients did not respond to the treatment. Tumor cells in effusion disappeared or significantly decreased and lymphocytes significantly increased in all responses. Except for transient fever in 9 patients, no serious side effects were found.

[Antimetastasis effect of lymphokine-activated killer (LAK) cells on fibrosarcoma in WKA rats]

Treating WKA rats with fibrosarcoma with LAK cells, antimetastasis effect was studied. The results indicated that splenocytes incubated by IL-2 could produce lytic activity to WKA rats with fibrosarcoma in vitro. Passive infusion of LAK cells lead to a marked reduction in the number of metastatic nodules in the lung. After intravenous injection of LAK cells, cancer cells in the lung speedily disappeared. LAK cell administration for 3 times gave better result than once only (P less than 0.01). In this paper, the possibility of LAK cells used as an adoptive immunotherapy for human neoplasms is briefly discussed.