Risk factors associated with catheter-related venous thrombosis: a meta-analysis.

BACKGROUND: So far, the risk factors of catheter-related venous thrombosis (CRVT) are not fully understood. We use evidence-based medicine to find the risk factors of CRVT by pooling the current studies that reported the risk factors of CRVT, aiming to provide guidance for clinical diagnosis and treatment. METHODS: We searched PubMed, Embase, and Cochrane Library from the establishment of the database to July 2021. We included studies that reported the risk factors of CRVT, and we excluded duplicate publications, research without full text, incomplete information or inability to conduct data extraction, animal experiments, reviews, and systematic reviews. STATA 15.1 was used to analyze the data. RESULTS: The pooled results show that history of venous thrombosis (odds ratio [OR] = 3.75, 95% confidence interval [CI]: 1.02-13.85; P = 0.047), cancer (OR = 1.74, 95% CI: 1.17-2.57; P = 0.006), infection (OR = 2.13, 95% CI:1.33-3.42; P = 0.002), and multilumina (OR = 3.34, 95% CI:1.48-7.54; P = 0.004) will significantly increase the occurrence of CRVT. However, there is no significant correlation between sex, congenital heart disease, bedridden state, sepsis, mechanical ventilation, anticoagulation therapy, insertion site (left), and CRVT. CONCLUSION: Our research results indicate that history of venous thrombosis, cancer, infection and multilumina are possible risk factors for CRVT, and corresponding preventive measures should be taken clinically.

LncRNA ST8SIA6-AS1 promotes colorectal cancer cell proliferation, migration and invasion by regulating the miR-5195/PCBP2 axis.

OBJECTIVE: Long non-coding RNAs (lncRNAs) have been reported to play a vital role in the development and progression of various cancers, including colorectal cancer (CRC). Although the dysregulation of lncRNA ST8SIA6-AS1 participates in the development of multiple malignancies, the underlying molecular mechanisms of ST8SIA6-AS1 in regulating CRC progression remain to be fully discovered. PATIENTS AND METHODS: The expression level of lncRNA ST8SIA6-AS1 was examined in the tumor tissues and paracancerous tissues of CRC patients. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was utilized to examine the expression levels of ST8SIA6-AS1, miR-5195, and Poly-(C) Binding Protein 2 (PCBP2). The protein expression level of PCBP2 was detected by Western blotting. MTT assay was performed to measure the proliferation of HCT-116 and SW480 cells. Cell migration and invasion abilities were measured by transwell assay. Luciferase reporter assay was used to examine the interaction between miR-5195 and ST8SIA6-AS1 or PCBP2. RESULTS: This study revealed that lncRNA ST8SIA6-AS1 was upregulated in CRC tissues and cells. Knockdown of ST8SIA6-AS1 inhibited proliferation, migration, and invasion of CRC cells. Moreover, ST8SIA6-AS1 was proved to inhibit miR-5195 expression by directly targeting miR-5195. In addition, it was demonstrated that overexpression of miR-5195 inhibited CRC progression. Furthermore, PCBP2 was shown to enhance sh-ST8SIA6-AS1 and miR-5195 mimics-attenuated cell proliferation, migration, and invasion by directly binding to miR-5195. CONCLUSIONS: Our study revealed that ST8SIA6-AS1 promoted CRC progression via the miR-5195/PCBP2 axis. This study may provide an improved understanding of the pathogenesis of CRC.

Synthesis, structure, magnetic and half-metallic properties of Co2-x Ru x MnSi (x = 0, 0.25, 0.5, 0.75, 1) compounds.

A series of Co2-x Ru x MnSi (x = 0, 0.25, 0.5, 0.75, 1) Heusler compounds were successfully synthesized. The heat-treatment conditions were crucial to make the materials form a single phase with a Heusler structure. With increasing Ru content, the half-metallic gap, lattice parameters and magnetization are continuously adjustable in a wide range. The Co2-x Ru x MnSi (x = 0, 0.25) compounds are rigorous half-metals and show a T 3 dependence of resistance at low temperature. The Co2-x Ru x MnSi (x = 0.5, 0.75, 1) Heusler compounds are the nearly half-metallic materials and show a semiconductive dependence of resistance at low temperature. The experimental magnetization is consistent with that in theory and follows the Slater-Pauling rule. The Curie temperature is higher than 750 K for all Co2-x Ru x MnSi Heusler compounds.

Preparation and physical properties of a Cr3Al film with a DO3 structure.

A Cr3Al compound with a DO3 structure has previously been predicted to be nearly half metal and a promising spintronics material; however, its synthesis has not been reported. Here, a Cr3Al compound with a DO3 structure is successfully prepared in thin-film form by the magnetron sputtering method. It was found that the substrate temperature is crucial to the atomic ordering, thin-film density and lattice constant. The lattice constant varies with different substrate temperatures and is smaller than the theoretical equilibrium lattice constant. Theoretical investigations on the electronic structures and magnetic properties indicate that the Cr3Al compound with a DO3 structure is a rare material with zero-gap half-metallic characteristics under an experimental lattice constant of 5.83 Å. The experimental result is in agreement with the theoretical results in magnetization, and the Cr3Al compound synthesized in this work exhibits semi-metallic-like electrical transport characteristics and positive magnetoresistance of greater than 2% in the temperature range 2-250 K.

Screening topological materials with a CsCl-type structure in crystallographic databases.

CsCl-type materials have many outstanding characteristics, i.e. simple in structure, ease of synthesis and good stability at room temperature, thus are an excellent choice for designing functional materials. Using high-throughput first-principles calculations, a large number of topological semimetals/metals (TMs) were designed from CsCl-type materials found in crystallographic databases and their crystal and electronic structures have been studied. The CsCl-type TMs in this work show rich topological character, ranging from triple nodal points, type-I nodal lines and critical-type nodal lines, to hybrid nodal lines. The TMs identified show clean topological band structures near the Fermi level, which are suitable for experimental investigations and future applications. This work provides a rich data set of TMs with a CsCl-type structure.

Effect of general anesthesia combined with epidural anesthesia on perioperative immune factors in cervical cancer.

Cervical cancer (CC) is a common malignant tumor that seriously threatens the health and life of female patients. At present, surgical resection remains as the preferred treatment for CC.

Tailoring structural and magnetic properties of Mn3-x Fe x Ga alloys towards multifunctional applications.

This study investigated the structural and magnetic properties of Mn3-x Fe x Ga alloys (x = 0, 0.2, 0.4, 0.6, 0.8, 1) under different heat-treatment conditions. A tetragonal structure was observed in samples that were heat treated at 623 K for three days followed by quenching in ice water. These tetragonal alloys present large coercive fields in the range 0.8-5 kOe and low saturation magnetization, and have great potential for application in spin-transfer torque-based devices. A hexagonal structure was observed in samples subjected to heat treatment at 883 K for three days following quenching in ice water. A moderate decrease in the coercive field has been observed for the hexagonal alloys compared with those with a tetragonal structure. However, the Mn3-x Fe x Ga alloys with a hexagonal structure exhibit other attractive magnetic properties, including collinear and non-collinear magnetic properties, holding high promise for technological applications. A face-centred-cubic (f.c.c.) structure was observed when subjected to annealing at 1073 K for three days followed by quenching in ice water. In contrast to the tetragonal and hexagonal structures, all f.c.c. alloys exhibit antiferromagnetic behaviour. This versatile material can display a wide range of multi-functionalities attributed to its tuneable crystal structure. This investigation will guide the design of multiple structures of these materials in order to utilise the wide functionalities for practical applications.

Transition from Anomalous Hall Effect to Topological Hall Effect in Hexagonal Non-Collinear Magnet Mn3Ga.

We report experimental observation of large anomalous Hall effect exhibited in non-collinear triangular antiferromagnet D019-type Mn3Ga with coplanar spin structure at temperatures higher than 100 K. The value of anomalous Hall resistivity increases with increasing temperature, which reaches 1.25 µΩ · cm at a low field of ~300 Oe at room temperature. The corresponding room-temperature anomalous Hall conductivity is about 17 (Ω · cm)-1. Most interestingly, as temperature falls below 100 K, a temperature-independent topological-like Hall effect was observed. The maximum peak value of topological Hall resistivity is about 0.255 µΩ · cm. The appearance of the topological Hall effect is attributed to the change of spin texture as a result of weak structural distortion from hexagonal to orthorhombic symmetry in Mn3Ga. Present study suggests that Mn3Ga shows promising possibility to be antiferromagnetic spintronics or topological Hall effect-based data storage devices.

Anti-site-induced diverse diluted magnetism in LiMgPdSb-type CoMnTiSi alloy.

The effect of three kinds of anti-site disorder to electronic structure and magnetic properties of the LiMgPdSb-type CoMnTiSi alloy are investigated. It was found the Mn-Ti anti-site disorder can induce the diluted magnetism in CoMnTiSi matrix. The magnetic structure has an oscillation between the ferromagnetic and antiferromagnetic states with the different degree of Mn-Ti anti-site disorder. Two novel characteristics: the diluted antiferromagnetic half-metallicity and the diluted zero-gap half-metallity are found in the different degree range of the Mn-Ti anti-site disorder. The Co-Mn and Co-Ti anti-site disorder have little effect on the magnetic properties. The width of energy gap and the intensity of DOS at the Fermi level can be adjusted by the degree of Co-Mn or Co-Ti anti-site disorder. The independent control to the carrier concentration and magnetization can be realized by introducing the different anti-site disorder.

Induction and identification of Stylosanthes guianensis tetraploids.

Stylosanthes guianensis is an elite and important forage legume species, which is extensively cultivated in tropical areas. Polyploid breeding via exposure to colchicine is a conventional and practical method to improve varieties of S. guianensis. Terminal buds of S. guianensis Reyan No.5 seedlings were treated with different concentrations of colchicine (0.00, 0.05, 0.10, 0.15, 0.20, and 0.25%) for 24, 48, and 72 h. Morphological and cytological variants were observed at a frequency of <96% among transplanted seedlings. The cytogenetic analysis of young leaf cells was conducted on all variants to identify their ploidy levels. The most efficient procedure for tetraploid production was the treatment of seedling apical buds with 20% colchicine for 48 h, with the tetraploid induction rate being 10%. This is a relatively simple and reliable method for the production of tetraploidy in S. guianensis.

Application of SRAP markers in the identification of Stylosanthes guianensis hybrids.

Sequence-related amplified polymorphism (SRAP) is a new molecular marker technology developed based on polymerase chain reaction. The authenticity of 84 progenies of 8 hybrid combinations of Stylosanthes guianensis was identified by SRAP markers to select the true hybrids used in the present study. A total of 35 SRAP primer combinations were selected from the parents of 8 hybrid combinations. The selected polymorphism primer combinations were applied to identify the authenticity of all progenies. The male parents of the primer combinations had specific markers, whereas the female parents did not. 68 progenies exhibited male parent-specific bands, which were identified as true hybrids. The rest of the progenies were considered self-hybrids because of the absence of male parent-specific bands. The results of hybrid identification provided solid evidence for further studies of hybrids and demonstrated SRAP molecular markers as a useful technology for assessing the purity of S. guianensis hybrids.

Bioinformatics analysis of gene expression profiles in the rat cerebral cortex following traumatic brain injury.

BACKGROUND: Traumatic brain injury (TBI) is a serious neurodisorder commonly caused by sports related events or violence. It is the leading cause of disability in people under 40. AIM: In order to elucidate the molecular mechanism of the secondary injury after TBI. MATERIALS AND METHODS: In this study, we downloaded gene expression profile on TBI model with sham controls for gene set enrichment analysis and pathway analysis. RESULTS: At a q-value of 5%, 361 genes were up-regulated and 373 were down-regulated in samples obtained at 48 hours after TBI. Functional analyses revealed that steroid biosynthesis, cell cycle, metal ion transport, inflammation and apoptosis were significantly dysregulated during the late period after trauma. In addition, MAPK3 (mitogen-activated protein kinase 3), was identified as the hub node in the protein-protein interaction (PPI) network constructed by the differentially expressed genes (DEGs). CONCLUSIONS: Further elucidation of genes and proteins in our study may reveal their potential as novel therapeutic targets.

First Report of Leaf and Sheath Spot Caused by Waitea circinata var. zeae on Paspalum vaginatum and Zoysia tenuifolia in China.

Waitea circinata var. zeae was previously reported as the causal agent of leaf and sheath spot on Festuca arundinacea (1) and Panicum tennesseense (2) in the United States. In late May to mid-September 2013, a disease resembling leaf and sheath spot was observed on Paspalum vaginatum in fairways from several golf courses in Hainan Province, China. Affected plants initially had large yellow and brown spots on leaves and sheathes, then the whole plant turned yellowish-brown and eventually died. The same symptoms were also observed on a lawn established with Zoysia tenuifolia in Hainan University. Symptomatic leaves were surface sterilized in 1% hypochlorite for 1 min, rinsed with sterile water three times, and plated onto potato dextrose agar (PDA) amended with 0.01% gentamicin sulfate. Two Rhizoctonia-like fungal isolates were obtained from the diseased P. vaginatum (Isolate no. ML-WC1) and Z. tenuifolia (Isolate no. HNU-1) samples. After incubation on PDA for 1 week at 25°C, white mycelial colonies developed and eventually turned a salmon color with age. Small, white, spherical sclerotia (0.5 to 1 mm in diameter) were observed submerged throughout the agar media after incubation for 1 week and turned a reddish-brown color within 4 weeks. The two isolates were tentatively identified as W. circinata var. zeae based on these characteristics. The internal transcribed spacer (ITS) region of the ribosomal DNA gene was amplified and sequenced using primer pair ITS1/ITS4. The sequences of the two isolates (GenBank Accession Nos. KJ717943 and KJ717944) were more than 99% similar to W. circinata var. zeae (JQ688056 and JQ688059) sequences deposited in GenBank. To confirm pathogenicity, inocula were prepared by incubating autoclaved rye grains with strains ML-WC1 and HNU-1 for 2 weeks at 25°C. Ten colonized rye grains were uniformly spread around the crowns of 6-week-old P. vaginatum and Z. tenuifolia seedlings grown in 10-cm-diameter pots. Each isolate was placed in four separate pots and four control plants were treated with non-inoculated grain. All pots were covered with translucent plastic bags and placed in a greenhouse at 24 ± 2°C with a 12-h light/dark cycle. By 1 week post-inoculation, significant blighting of leaves and sheaths was observed, while non-inoculated plants showed no symptoms. W. circinata var. zeae was successfully re-isolated from symptomatic plants and confirmed by its Rhizoctonia-like mycelium and small, reddish-brown, spherical sclerotia on the PDA. Recently a related species, W. circinata var. circinata, causing brown ring patch on two cool-season grasses was reported in China (3). However, the isolates of W. circinata var. zeae were distinguished from W. circinata var. circinata base on ITS sequence data and morphological characters. To our knowledge, this is the first report of W. circinata var. zeae infecting P. vaginatum and Z. tenuifolia in China. References: (1) S. S. Martin, Jr. and L. T. Lucas. Plant Dis. 67:676, 1983. (2) N. A. Mitkowski. Plant Dis. 87:1006, 2003. (3) X. X. Ni et al. Plant Dis. 96:12, 2012.

A novel root-end filling material based on hydroxyapatite, tetracalcium phosphate and polyacrylic acid.

AIM: To develop a novel root-end filling material (NRFM) based on hydroxyapatite, tetracalcium phosphate and polyacrylic acid, to determine its chemical composition and to compare its physical properties and cytotoxicity with those of glass-ionomer cement (GIC) and grey Portland cement (GPC). METHODOLOGY: The NRFM was prepared by blending distilled water with powders of hydroxyapatite, tetracalcium phosphate, solid polyacrylic acid, solid citric acid and sodium citrate. Chemical analysis was then performed by X-ray diffraction and Fourier transform infrared spectrophotometry. Physical properties were compared with GIC and GPC regarding setting time, compressive strength, pH value and washout resistance; cytotoxicity was assessed using a transwell cell culture system. RESULTS: (i) The NRFM was primarily composed of HA, calcium polyacrylate and calcium citrate. (ii) The mean and standard deviation setting time of NRFM was 11.0 (0.8) min; its compressive strength was 25.6 (2.7) MPa and 38.2 (5.7) MPa at 1 and 7 days respectively. Its pH value ranged from 6.14 to 8.28 and it remained intact after the washout test, whereas GIC and GPC disintegrated. (iii) Dimethyl-thiazol-diphenyl tetrazolium bromide (MTT) and crystal violet (CV) assay revealed that cell-viability on the NRFM was not significantly different form that of the negative control group after treatment for 24, 48 and 72 h. CONCLUSION: The novel root-end filling material (NRFM) is a promising root-end filling material with good physicochemical properties and low cytotoxicity.

First Report of Limonomyces roseipellis Causing Pink Patch on Bermudagrass in South China.

Hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy) is widely used on golf course putting greens in southern China. In September 2011, circular pink patches ranging from 10 to 20 cm in diameter were observed on putting greens established with cv. 'Tifgreen' on a golf course in Haikou, Hainan Province. There were approximately 50 pink patches on a putting green. Infected leaves were covered with pink, gelatinous fungal mycelium, which resulted in the production of chlorotic lesions. Lesions expanded, became water-soaked, and leaves died basipetally. A pink fungus, characterized by the presence of clamp connections, was consistently isolated from leaves of infected plants on a potato dextrose agar amended with 0.01% gentamicin sulfate. Based on morphological characteristics, the fungus was preliminary identified as Limonomyces roseipellis Stalpers & Loerakker, the causal agent of pink patch of turfgrass (2,3). To verify the identity, the internal transcribed spacer (ITS) of rDNA was amplified and sequenced using primers ITS1 and ITS4. Comparison with sequences in the GenBank database revealed that the ITS sequence (Accession No. KC193592) showed 98% homology with the sequence of L. roseipellis (EU622846). For pathogenicity tests, inoculum was prepared by culturing the fungus on an autoclaved mixture of 100 g of rye grain and 20 ml water for 3 weeks at 25°C. Six-week-old C. dactylon plants in 10-cm pots were inoculated by placing 2 g of infested grain in the center of the turf canopy, or 2 g sterilized, uninfested grain as a control, with four replications of each treatment. After inoculation, pots were covered with translucent plastic bags and placed in a greenhouse at 24 ± 2°C with a 12-h photoperiod (1). After 3 weeks, more than 70% of leaves in the infested pots showed symptoms identical to those observed under natural conditions while control plants remained asymptomatic. The fungus was reisolated from symptomatic plants. To our knowledge, this is the first report of L. roseipellis causing pink patch on hybrid bermudagrass in China. References: (1) L. L. Burpee and L. G. Goulty. Phytopathology 74:692, 1986. (2) J. D. Kaplan and N. Jackson. Plant Dis. 67:159, 1983. (3) J. A. Stalpers and W. M. Loerakker. Can. J. Bot. 60:529, 1982.

First Report of Laetisaria fuciformis Causing Red Thread on Seashore Paspalum (Paspalum vaginatum) in South China.

Seashore paspalum (Paspalum vaginatum Swartz.) is a prostrate-growing, perennial, warm-season turfgrass native to tropical and coastal areas (2). Because of its good texture and natural tolerance to various environmental stresses, seashore paspalum has been introduced to golf courses in coastal regions of southern China. In April 2010, circular or irregular pink patches ranging from 5 to 50 cm in diameter were observed in the golf course fairway and rough established with cv. Salam on two golf courses in Haikou, Hainan Province, China. When morning dew was present or rainfall occurred, a pink layer of gelatinous fungal growth could be observed on leaves and sheaths. The green leaves of infected plants initially became water soaked, then tan to bleached, shriveled, and infested with pink or reddish, gelatinous, stranded hyphae. The hyphae matted together, then formed threadlike or antlerlike stromata from the tips of blighted leaves. Two isolates from each golf course were collected by plating diseased leaf blades, stromata, or hyphal aggregates from the blighted leaves directly onto antibiotic (0.01% gentamicin sulfate) amended potato dextrose agar. To confirm pathogenicity, isolates were inoculated on 6-week-old P. vaginatum (cv. Seaspray) planted (0.5 mg seed/cm-2) in 10-cm pots. Inoculum was prepared by culturing isolates separately on an autoclaved mixture of 100 g of rye grain and 20 ml of water for 3 weeks at 25°C. Pots were inoculated by placing 2 g of infected grain within the center of the turf canopy or 2 g of sterilized, uninfested grains to serve as controls, with four replications of each treatment. After inoculation, each pot was placed in a translucent plastic bag and placed into a greenhouse at 24 ± 2°C with a 12-h photoperiod (1). Two days after inoculation, the fungus was observed on the leaves. Approximately 40% of leaves in inoculated pots were necrotic after 7 days, and this increased to 80% after 21 days. Diseased plants in inoculated pots displayed symptoms similar to those observed in the field and no symptoms were detected on the control plants. The two isolates were successfully reisolated from all symptomatic tissues, completing Koch's postulates. Sequences of mitochondrial small subunit ribosomal RNA (mt-SSU) were amplified from the two isolates by primers MS1 and MS2, and the sequences showed 99% similarity with Laetisaria fuciformis from the NCBI database (Accession No. AY293232). Red thread on turfgrass has been commonly observed in temperate climates during periods of cool and humid weather (3). To our knowledge, this is the first report of L. fuciformis causing red thread on P. vaginatum or from any host plant in China. References: (1) L. L. Burpee and L. G. Goulty. Phytopathology. 74:692, 1984. (2) R. R. Duncan and R. N. Carrow. Seashore Paspalum: The Environmental Turfgrass. John Wiley and Sons, Toronto, ON, Canada, 2000. (3) R. W. Smiley et al. Page 38 in: Compendium of Turfgrass Diseases. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2005.

Phosphorus release from ash and remaining tissues of two wetland species after a prescribed fire.

Dead plant tissues and ash from a prescribed fire play an important role in nutrient balance and cycling in the Florida Everglades ecosystem. The objective of this study was to assess the dynamic changes in total phosphorus release (TPr) from ash or tissues of either cattail (Typha domingensis Pers.) or sawgrass (Cladium jamaicense Crantz) to water. Natural-dead (senesced-dead) and burning-dead (standing-dead due to a prescribed fire) cattail and sawgrass were collected from highly (H) and moderately (M) impacted zones in the Florida Everglades. This experiment was conducted by incubation and water-extraction of the materials in plastic bottles for 65 d at room temperature (24 +/- 1 degrees C). Results showed that 63 to 88%, 17 to 48%, 9 to 20%, and 13 to 28% of total P (TPp) were released as TPr from cattail and sawgrass ash, cattail tissues from the H zone, cattail tissues, and sawgrass tissues from the M zone, respectively. TPp means total P of plant tissues, whereas TPr is total P release from the tissues or ash. Most of the TPr was released within 24 h after burning. The quick release of TPr observed in this experiment may help explain the P surge in the surface water immediately following a fire in the marsh. These findings suggest that prescribed burning accelerates P release from cattail and sawgrass. They also imply that it is very important to keep the water stagnant in the first 24 h to maximize the benefits of a prescribed fire in the Everglades.

Fluorescence spectral study of interaction of water-soluble metal complexes of Schiff-base and DNA.

The fluorescence spectral characteristics and the interaction of several water-soluble metal complexes of Schiff-base with DNA are described. Among the complexes tested, Mn-Schiff-base bound to DNA showed a marked decrease in the fluorescence intensity with a blue shift of the excitation and emission peaks. Some hypochromism in the UV absorption spectra was also observed. KI quenching and competitive binding to DNA between Mn-Schiff-base and ethidium bromide (EB) were studied in connection with other experimental observations to show that the interactive model between Mn-Schiff-base and DNA is an intercalative one. The pH and salt effect on the fluorescence properties was also investigated. The linear relationship between F/F0 and the concentration of calf thymus DNA covers 3.0 x 10(-6)-2 x 10(-4) mol L-1, which can be utilized for determining traces of calf thymus DNA with a detection limit of 8.0 x 10(-7) mol L-1 in base pairs.

Renewable amperometric immunosensor for complement 3 assay based on the sol-gel technique.

A renewable amperometric immunosensor based on the sol-gel technique has been constructed by dispersing graphite, complement 3 (C3) antiserum, and sol-gel at low temperature. The prepared immunosensor is rigid, porous, and has a renewable external surface. A competitive binding assay has been used to determine C3 in human serum with the aid of C3 labeled with horseradish peroxidase. The enzyme-labeled antigen can readily diffuse toward the encapsulated antibody, which retains its binding properties. The experimental conditions for the assay with the biocomposite, including the loading of C3 antiserum in the biocomposite, the amount of labeled C3 in incubation solution, incubation time, and temperature, have been optimized. Using C3 labeled with horseradish peroxidase, and o-AP as the substrate, amperometric detection at -150 mV (relative to the SCE) results in a linear detection range of 1.17-35.1 microg mL(-1), with a detection limit of 0.56 microg mL(-1). Serum samples have been assayed and the results demonstrate the feasibility of the proposed immunosensor for clinical analysis. The surface of the immunosensor can be renewed simply by polishing to obtain a fresh immunocomposite ready to use in a new competitive assay.

Renewable amperometric immunosensor for Schistosoma japonium antibody assay.

A renewable amperometric immunosensor has been proposed for the determination of Schistosoma japonium antibody (SjAb) in rabbit serum. A paraffin-graphite-Schistosoma japonium antigen (SjAg) biocomposite, which needs no additional curing, was directly used to construct the immunosensors. The analytical sample containing the desired SjAb was mixed with SjAb labeled with horseradish peroxidase (HRP) to form the incubation solution for the competitive binding assay. Amperometry was used to determine the amount of HRP fixed on the sensor surface, which was related to the content of desired SjAb. Assay conditions were optimized, including the selection of substrate, the loading of SjAg in the biocomposite, the amount of labeled SjAb in the incubation solution, the incubation time, and the temperature. Using o-aminophenol (o-AP) as a substrate, amperometric detection at -200 mV (vs SCE) resulted in a pseudolinear detection range of about 0.36 to 14 microg/mL, with a detection limit of 0.36 microg/mL. Rabbit serum samples with varying infection degrees were analyzed, and the results demonstrated that the concentration that is detectable in this system meets the demands of clinical analyses. A new surface on the immunosensor for use in another competitive assay can be obtained by removing the original one and polishing the surface.