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Biomedical subjects

J Xu

Publications and source records attributed to J Xu.

At least 55 records · Page 3Linked to original sources
PubMed2006

Influence of hydroxyethyl starch 130/0.4 in pulmonary neutrophil recruitment and acute lung injury during polymicrobial sepsis in rats.

BACKGROUND: Acute lung injury (ALI) is a progressive syndrome associated with significant mortality in sepsis patients. Neutrophils are key cells in the inflammatory response that characterizes ALI. This study was designed to explore the effects of hydroxyethyl starch (HES) 130/0.4 (a novel plasma substitute) on pulmonary neutrophil recruitment and associated ALI in a rat sepsis model induced by cecal ligation and puncture (CLP). METHODS: Animals were randomly assigned to six groups [saline control; CLP and saline; CLP and HES (7.5, 15 and 30 ml/kg); and HES control], subjected to CLP and infused with or without HES 130/0.4 4 h after CLP. Six hours later, the pulmonary capillary permeability (PCP), myeloperoxidase (MPO) activity, lung histological changes, tumor necrosis factor-alpha, interleukin-1beta and cytokine-induced neutrophil chemoattractant levels, P-selectin mRNA expression and nuclear factor-kappa B (NF-kappaB) activation were measured. RESULTS: Resuscitation with HES 130/0.4 significantly attenuated the CLP-induced increase in PCP, MPO activity, cytokine/chemokine levels, mRNA expression of P-selectin and NF-kappaB activation, all of which are involved in the recruitment of neutrophils. Groups receiving the higher doses of HES 130/0.4 (15 and 30 ml/kg) were more adequately resuscitated. CONCLUSION: HES 130/0.4 can inhibit CLP-induced neutrophil recruitment and subsequent ALI by attenuating cytokines/chemokines, adhesion molecule-mediated inflammation and NF-kappaB activation.

Animals↗
PubMed2006

High interlaboratory reproducibility of DNA sequence-based typing of bacteria in a multicenter study.

Current DNA amplification-based typing methods for bacterial pathogens often lack interlaboratory reproducibility. In this international study, DNA sequence-based typing of the Staphylococcus aureus protein A gene (spa, 110 to 422 bp) showed 100% intra- and interlaboratory reproducibility without extensive harmonization of protocols for 30 blind-coded S. aureus DNA samples sent to 10 laboratories. Specialized software for automated sequence analysis ensured a common typing nomenclature.

Bacterial Typing Techniques↗
PubMed2006

Three dimensional optic disc visualisation from stereo images via dual registration and ocular media optical correction.

BACKGROUND/AIMS: The three dimensional (3-D) visualisation of the optic disc in true colour will give essential meaning in clinical application. It is not only useful for clinicians in the evaluation of the condition of the optic disc, but it also simplifies the pathological diagnosis and disease progression monitoring. This paper describes a complete 3-D optic disc reconstruction method from a pair of stereo images by a series of robust procedures including camera calibration, image registration, depth recovery, and ocular media optical inclusion. METHODS: Two registration techniques (correlation and feature based methods) are combined together to prune the uncertain matching points in order to improve the overall accuracy of registration. The ocular media within the eyeball are lump modelled as a single lens and integrated into the reconstruction process to obtain an accurate 3-D optic disc image. CONCLUSION: The recovered 3-D optic disc images show good consistency and compatibility when compared with the results from Heidelberg retina tomography (HRT) under clinical validation, with an additional advantage of implementing a more economical and conventional mode of retinal image acquisition.

Algorithms↗
PubMed2006

Cyclooxygenase-2 plays an essential part in cardioprotection of delayed phase of recombinant human erythropoietin preconditioning in rats.

AIMS: To study the cardioprotection of recombinant human erythropoietin (rhEPO) preconditioning (EPC) and to investigate the role and possible mechanism of cyclooxygenase (COX)-2 in the delayed phase of EPC. METHODS: In phase 1, myocardial ischaemia reperfusion (I-R) rat model was established by 30 minutes ligation of left descending coronary and three hours of reperfusion. Rats were given 0.9% saline solution or rhEPO 24 hours before I-R protocol. COX-2 selective inhibitor celecoxib was given for further investigation of the cardioprotection of EPC. At the end of I-R protocol, infarct sizes were measured and ultrastructural organisations were studied. In phase 2, myocardial COX-2 mRNA expressions and prostaglandins (PGs) contents were studied in different groups after euthanasia. RESULTS: It was found that EPC could elicit potent cardioprotection against I-R injury, shown by reduction of infarct size and improvement of ultrastructural organisation; whereas administration of celecoxib resulted in complete loss of this protection. EPC resulted in robust increase in COX-2 mRNA and PGs levels that were also abrogated by celecoxib. CONCLUSIONS: COX-2 plays an essential part in cardioprotection of the delayed phase of EPC in rats, which might be related to actions of PGE(2) or PGI(2), or both.

Animals↗
PubMed2006

Serine proteases and metalloproteases associated with pathogenesis but not host specificity in the Entomophthoralean fungus Zoophthora radicans.

The protease activity of a Zoophthora radicans strain that was highly infective toward Pieris brassicae (cabbage butterfly) larvae was compared with that of isogenic strains that were adapted to Plutella xylostella (diamondback moth) larvae through serial passage. All strains produced three distinct serine proteases ranging in size from 25 to 37 kDa; however, the original strain from P. brassicae also produced large amounts of an approximately 46 kDa metalloprotease. Subsequently, a cDNA encoding a 43 kDa (mature enzyme) zinc-dependent metalloprotease, ZrMEP1, was isolated from the original fungal strain and most likely corresponds to the 46 kDa protease observed with in-gel assays. ZrMEP1 possessed characteristics of both the fungalysin and thermolysin metalloprotease families found in some pulmonary and dermal pathogens. This is the first report of this type of metalloprotease from an entomo pathogenic fungus. A cDNA encoding a trypsin-like serine protease, ZrSP1, was also identified and was most similar to a serine protease from the plant pathogen Verticillium dahliae. In artificial media, ZrMEP1 and ZrSP1 were found to be differentially responsive to gelatin and catabolite repression in the fungal strains adapted to P. brassicae and P. xylostella, but their expression patterns within infected larvae were the same. It appears that while these proteases likely play a role in the infection process, they may not be major host specificity determinants.

Amino Acid Sequence↗
PubMed2006

Bone allograft non-union is related to excessive osteoclastic bone resorption: a sheep model study.

Using a sheep femoral allograft model we have investigated the cellular and molecular mechanisms associated with non-union of bone allografts. Histomorphometric analysis revealed that allograft non-unions featured both marked increases in osteoclast (OC) numbers and total eroded bone surface as compared to allografts which had undergone direct union. Three distinct cellular layers lying adjacent to the allograft bone surface were identified in all non-union cases. The outer or fibroblastic layer contained an abundance of fibroblasts and connective tissue. Circumscribing this layer was a band of synovial-like cells consisting mainly of large spindle-shaped mononuclear cells mixed with scattered round-shaped mononuclear cells. The third layer, which was directly juxtaposed to the allograft bone surface, consisted predominantly of multinuclear OCs which were positively identified by calcitonin receptor immunohistochemistry. Interestingly, in-situ hybridisation revealed that surrounding synovial-like cells in non-union allografts, expressed abundant gene transcripts for receptor activator NF-kappaB ligand (RANKL), a membrane bound factor critical for both the induction of OC activity and osteoclastogenesis. We propose that excessive bone resorption by host OCs contributes, at least partially, to the failure of bone allografts. The production of RANKL by synovial-like fibroblasts may be the driving force responsible for the elevated generation and activation of OCs. Based on such evidence novel therapeutic strategies for the treatment of non-union bone allografts using anti-bone resorbing agents may be devised.

Animals↗
PubMed2006

Structural and functional design of WWTP operation decision support system with a case study.

This paper developes the WWTP operation decision support system (ODSS) to simulate the dynamic behavior of the WWTP treatment process based on ASMs (activated sludge models) and WWTP experiential knowledge. The novel structure and functions of ODSS can offer more flexible and general instructions to the WWTP operations. The three independent sub-systems, namely expert system, simulation system and training system, can cooperate to achieve many more functions such as operation alert, fault diagnosis, process simulation and so forth. The expert system based on the dynamic simulation, an essential part of WWTP ODSS, has been proved to be feasible and effective by the implementation at Fang Zhuang WWTP. Our results indicated that the WWTP ODSS has significant potential for improving plant performance and reducing treatment costs by assisting the operators at the decision-making level.

Decision Making↗
PubMed2006

Developmental potential of vitrified holstein cattle embryos fertilized in vitro with sex-sorted sperm.

In vitro fertilization (IVF) is a feasible way to utilize sex-sorted sperm to produce offspring of a predetermined sex in the livestock industry. The objective of the present study was to examine the effects of various factors on bovine IVF and to systematically improve the efficiency of IVF production using sex-sorted sperm. Both bulls and sorting contributed to the variability among differential development rates of embryos fertilized by sexed sperm. Increased sorting pressures (275.8 to 344.75 kPa) did not have a significant effect on the in vitro fertility of the sorted sperm; neither did an extended period of 9 to 14 h from semen collection to sorting. As few as 600 sorted sperm were used to fertilize an oocyte, resulting in blastocyst development of 33.2%. Postwarming of vitrified sexed IVF embryos resulted in high morphological survival (96.3%) and hatching (84.4%) rates, similar to those fertilized by nonsexed sperm (93.1 and 80.6%, respectively). A 40.9% pregnancy rate was established following the transfer of 3,627 vitrified, sexed embryos into synchronized recipients. This was not different from the rates with nonsexed IVF (41.9%, n = 481), or in vivo-produced (53.1%, n = 192) embryos. Of 458 calves born, 442 (96.5%) were female and 99.6% appeared normal. These technologies (sperm sexing-IVF-vitrification-embryo transfer) provide farmers, as well as the livestock industry, with a valuable option for herd expansion and heifer replacement programs. In summary, calves were produced using embryos fertilized by sex-sorted sperm in vitro and cryopreserved by rapid cooling vitrification.

Animals↗
PubMed2006

Evidence of circulating donor genetic material in bone allotransplantation.

Musculoskeletal allotransplantion is the most common form of human tissue transplantation. Unlike solid organ transplants, bone allotransplants undergo rigorous processing and are considered non-viable tissue. In this study, we propose that donor genetic material may exist in circulation after bone allotransplantation. Fifty-one female patients who received bone allotransplants from male donors were assessed. Blood plasma samples were analyzed using real-time quantitative polymerase chain reaction (PCR) with dual labeled fluorogenic probes for the presence of the SRY gene on the Y chromosome. Of the total 51 patients, the SRY sequence was detected in 6 patients. Five were positive at day 1 postoperatively and negative thereafter, with the remaining patient positive at 3 months post-transplantation. Our results document, for the first time, the presence of donor DNA in the circulation of recipients after bone allotransplantation. Our findings suggest a potential new investigative tool to assess the postoperative status of bone allotransplants.

Bone Remodeling↗
PubMed2006

[Significance of hepatitis B virus PreS1-Ag, PreS2-Ag, large protein, PreS2-Ab detection and the prediction of HBV DNA replication.].

BACKGROUND: To explore the significance of hepatitis B virus PreS1-Ag, PreS2-Ag, large protein (LP) detection and the prediction of viral replication. METHODS: PreS1-Ag, PreS2-Ag, LP and HBV markers were measured by enzyme linked immunosorbent assay (ELISA) in 201 cases of infected serum. Serum HBV DNA level was quantitatively detected by real-time polymerase chain reaction (PCR). RESULTS: There were significant differences in positive rate between the PreS1-Ag, PreS2-Ag, LP, and HBsAg; the positive rate of PreS2-Ag and LP were higher than that of the HBeAg. No significant differences were found in the positive rates between LP and the levels of HBV DNA and there was a positive correlation between quantitations of HBV DNA and HBV-LP. CONCLUSION: Serum PreS1-Ag, PreS2-Ag and LP were laboratory markers that can accurately reflect HBV DNA reproduction, and were helpful complementarity to traditional HBV M. There is a close correlation between the number of copies of HBV DNA and the levels of HBV-LP.

DNA Replication↗
PubMed2005

NMR study of orientational ordering in the chiral- phase of partially deuterated smectic liquid crystals.

Carbon-13 NMR spectroscopy is used to probe the orientational ordering in the tilted chiral smectic phase of two partially deuterated liquid crystals. Quantitative analyses of the chemical shifts of the aromatic carbons in the smectic- and - phases enable us to obtain the location of the long molecular axis of the core and the off-diagonal order parameter of the molecular core in the smectic- phase. The advantage of knowing the ordering information of these molecules in their mesophases from deuteron studies is demonstrated in this work, as they can be used to guide the assignments. The temperature behaviors of the chemical shifts from the aromatic sites in the helical structure of the smectic- phase is caused by both an increase of the tilt angle and a change in the orientation of the principal frame that describes the molecular ordering.

Journal Article↗
PubMed2005

Interlayer jump diffusion in the smectic-C*A phase by angular-dependent NMR study.

A detailed 2H nuclear magnetic resonance (NMR) study at 61.4 MHz of two chiral smectic C phases of a smectogen 10B1M7, one ferroelectric (SmC*) and the other antiferroelectric (SmC), is reported. Simulation of angular-dependent spectral patterns and/or signal intensities of the methyl deuterons are shown to provide information on the synclinic or anticlinic ordering, as well as the jump diffusion rates at different temperatures in the SmC phase. The molecular self-diffusion constant is determined to be in the range of 0.2-1.2 x 10(-14) m2/s over the temperature range of the SmC phase. Molecular self-diffusion in the SmC* phase should be faster, but remains undetectable by the present approach. Furthermore, the phase biaxiality in these phases is found to be vanishingly small. The critical magnetic field for unwinding the helical structure of 10B1M7 is found to be relatively high.

Journal Article↗
PubMed2005

The impact of ethnicity and sex on subclinical cardiovascular disease: the Diabetes Heart Study.

AIMS/HYPOTHESIS: African-Americans with type 2 diabetes and access to adequate healthcare are at lower risk of clinical coronary artery disease than are white diabetic patients. We evaluated whether ethnic differences in subclinical cardiovascular disease, coronary and carotid artery calcified plaque and carotid artery intima-medial thickness (IMT) were present in members of The Diabetes Heart Study families. SUBJECTS AND METHODS: In a bi-racial cohort of 1,180 individuals from families enriched for members with type 2 diabetes, we calculated coronary and carotid artery calcified plaque using fast-gated helical computed tomography, and measured carotid artery IMT and clinical risk factor profiles. Generalised estimating equations were used to test for an association between measures of subclinical cardiovascular disease and ethnicity and sex. RESULTS: After adjustment for age, ethnicity and kidney function, African-Americans had significantly lower amounts of coronary artery calcified plaque (mean+/-SE) (866+/-158 vs 1,915+/-135, respectively; p=0.0466) and carotid artery calcified plaque (179+/-51 vs 355+/-27, respectively; p=0.0240) relative to whites, despite having increased carotid IMT (0.71+/-0.01 vs 0.67+/-0.004 cm, respectively; p=0.0007), and higher blood pressure, albuminuria and HbA1c. Sex-specific analyses revealed that African-American men had significantly lower coronary and carotid artery calcified atheroma than white men. In women, ethnic differences in calcified carotid artery plaque, but not coronary artery plaque, were observed. CONCLUSIONS/INTERPRETATION: In families enriched for members with type 2 diabetes, African-American men had markedly lower levels of coronary and carotid artery calcified plaque than white men, despite increased carotid artery IMT and conventional risk factors. These findings suggest that susceptibility to subclinical cardiovascular disease differs markedly according to ethnicity and sex.

Adult↗
PubMed2005

Structural analysis of a set of proteins resulting from a bacterial genomics project.

The targets of the Structural GenomiX (SGX) bacterial genomics project were proteins conserved in multiple prokaryotic organisms with no obvious sequence homolog in the Protein Data Bank of known structures. The outcome of this work was 80 structures, covering 60 unique sequences and 49 different genes. Experimental phase determination from proteins incorporating Se-Met was carried out for 45 structures with most of the remainder solved by molecular replacement using members of the experimentally phased set as search models. An automated tool was developed to deposit these structures in the Protein Data Bank, along with the associated X-ray diffraction data (including refined experimental phases) and experimentally confirmed sequences. BLAST comparisons of the SGX structures with structures that had appeared in the Protein Data Bank over the intervening 3.5 years since the SGX target list had been compiled identified homologs for 49 of the 60 unique sequences represented by the SGX structures. This result indicates that, for bacterial structures that are relatively easy to express, purify, and crystallize, the structural coverage of gene space is proceeding rapidly. More distant sequence-structure relationships between the SGX and PDB structures were investigated using PDB-BLAST and Combinatorial Extension (CE). Only one structure, SufD, has a truly unique topology compared to all folds in the PDB.

Databases, Protein↗
PubMed2005

Interleukin-1 receptor antagonist haplotype associated with prostate cancer risk.

IL1-RN is an important anti-inflammatory cytokine that modulate the inflammation response by binding to IL1 receptors, and as a consequence inhibits the action of proinflammatory cytokines IL1alpha and IL1beta. In this study, we hypothesise that sequence variants in the IL1-RN gene are associated with prostate cancer risk. The study population, a population-based case-control study in Sweden, consisted of 1383 prostate cancer case patients and 779 control subjects. We first selected 18 sequence variants covering the IL1-RN gene and genotyped these single-nucleotide polymorphisms (SNPs) in 96 control subjects. Gene-specific haplotypes of IL1-RN were constructed and four haplotype-tagging single-nucleotide polymorphisms (htSNPs) were identified (rs878972, rs315934, rs3087263 and rs315951) that could uniquely describe >95% of the haplotypes. All study subjects were genotyped for the four htSNPs. No significant difference in genotype frequencies between cases and controls were observed for any of the four SNPs based on a multiplicative genetic model. Overall there was no significant difference in haplotype frequencies between cases and controls; however, the prevalence of the most common haplotype (ATGC) was significantly higher among cases (38.7%) compared to controls (33.5%) (haplotype-specific P = 0.009). Evaluation of the prostate cancer risk associated with carrying the 'ATGC' haplotype revealed that homozygous carriers were at significantly increased risk (odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.2-2.2), compared to noncarriers, while no significant association was found among subjects heterozygous for the haplotype (OR = 1.0, 95% CI = 0.8-1.2). Restricting analyses to advanced prostate cancer strengthened the association between the 'ATGC' haplotype and disease risk (OR for homozygous carriers vs noncarriers 1.8, 95% CI = 1.3-2.5). In conclusion, the results from this study support the hypothesis that inflammation has a role of in the development of prostate cancer, but further studies are needed to identify the causal variants in this region and to elucidate the biological mechanism for this association.

Aged↗
PubMed2005

Long-term effect of maternal obesity on pancreatic beta cells of offspring: reduced beta cell adaptation to high glucose and high-fat diet challenges in adult female mouse offspring.

AIM/HYPOTHESIS: Obesity is a global problem with high risks of cardiovascular diseases, stroke and type 2 diabetes. It is well known that maternal obesity affects offspring by inducing malformation, functional abnormalities in many organs and cells, and by increased risk of obesity and type 2 diabetes. However, little is known about abnormalities induced by maternal obesity in pancreatic beta cells of offspring. METHODS: We used mouse mothers with the Agouti yellow modification on a C57BL/6 background as a maternal model of normoglycaemic obesity, and produced Agouti-negative offspring. Half of the offspring were fed a high-fat diet. Offspring glucose tolerance was tested at different ages, and animals were killed at 50 weeks of age for islet function analysis. RESULTS: Maternal obesity impaired glucose tolerance in female offspring fed a high-fat diet, and significantly reduced insulin secretion at 50 weeks of age in female offspring that had been fed a normal diet and high-fat diet. Insulin secretion and glucose potentiation from these islets were significantly reduced. Islet protein, DNA and insulin contents were increased while glyceraldehyde-3-phosphate dehydrogenase and transketolase activities were reduced in female offspring. CONCLUSIONS/INTERPRETATION: Our results indicate that maternal obesity has a long-term effect on the beta cells of female, but not of male, offspring, and leads to increased risk of gestational diabetes and type 2 diabetes in the offspring's later lives.

Acclimatization↗
PubMed2005

Neutralizing antibodies and efficacy of interferon beta-1a: a 4-year controlled study.

OBJECTIVE: To determine the incidence and clinical significance of neutralizing antibody (NAb) formation in patients with relapsing multiple sclerosis (MS) who participated in the European Interferon Beta-1a IM Dose-Comparison Study. METHODS: Patients were randomized to treatment with interferon beta-1a (IFNbeta-1a) 30 microg or 60 microg IM once weekly for up to 4 years. Serum samples obtained at baseline and every 3 months thereafter were screened for the presence of IFN binding antibodies by ELISA. Patients whose results were seropositive on ELISA were screened for the presence of NAbs using an antiviral cytopathic effect assay. Patients were considered to be positive for NAbs (NAb+) if the baseline NAb titer was 0 and two or more consecutive postbaseline titers were > or = 20. Patients were considered to be negative for NAbs (NAb-) if the baseline NAb titer was 0 and all postbaseline NAb titers were < 5. RESULTS: The proportion of patients who became NAb+ was lower in patients who received 30 microg of IFNbeta-1a than in those who received 60 microg (7/400 [1.8%] vs 19/395 [4.8%]; p = 0.02). The mean time to NAb+ status was 14.5 +/- 6.2 months. Compared with patients who remained NAb-, NAb+ patients showed the following: higher relapse rates from months 12 to 48 (p = 0.04), higher rate of mean change (worsening) in Expanded Disability Status Scale score from baseline to month 48 (p = 0.01), greater number of T1 gadolinium-enhanced lesions at months 24 and 36 (p = 0.02 and 0.03), and greater accrual of new or enlarging T2 lesions from month 12 to months 24 and 36 (p = 0.05 and 0.09). CONCLUSIONS: Neutralizing antibodies (NAbs) to interferon beta-1a (IFNbeta-1a), as observed with other IFNbetas used in the treatment of multiple sclerosis, reduce the therapeutic benefits measured by relapses and MRI activity. Data from this study also suggest NAbs to IFNbeta-1a reduce treatment benefits as measured by change in Expanded Disability Status Scale score.

Adult↗