Biomedical subjects

Y Chen

Publications and source records attributed to Y Chen.

At least 109 records · Page 6Linked to original sources

PubMed2005

Osteopetrosis-like phenotype in latent TGF-beta binding protein 3 deficient mice.

LTBPs are extracellular matrix proteins resembling fibrillins. LTBP-1, 3, and 4 covalently bind latent TGF-beta and modulate tissue levels of this potent cytokine through regulation of its secretion, localization, and/or activation. To address LTBP function in vivo, we generated Ltbp-3 null mice. Ltbp-3-/- animals developed craniofacial abnormalities due to early ossification of the skull base synchondroses and displayed reduced body size. In addition, histological examination of Ltbp-3-/- skeletons revealed an increase in bone mass. The osteoblast numbers and mineral apposition rates were decreased in Ltbp-3-/- mice, whereas the osteoclast numbers were similar in null and wild type mice. Histological examination revealed persistence of cartilage remnants in Ltbp-3-/- trabecular bone. Taken together, these results indicate that the Ltbp-3-/- high bone mass phenotype was due to a defect in bone resorption. We hypothesize that lack of Ltbp-3 results in decreased levels of TGF-beta in bone and cartilage, which leads to compromised osteoclast function and decreased bone turnover.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Beta cell function and response to treatment in Nigerians with Type 2 diabetes mellitus.

There are scant data from African populations on the association between beta-cell function and response to treatment with oral hypoglycaemic agents in Type 2 diabetes mellitus (T2DM). Fasting plasma C-peptide (FCP) and glucagon-stimulated C-peptide (GSCP) levels were measured in 116 Nigerians with T2DM at a university teaching hospital. After 9 months of follow-up and treatment, they were categorized into three groups based on response to treatment: (A) good control but not on maximum sulphonylurea (SU) therapy, (B) inadequate control but not on maximum SU therapy and (C) on maximum SU therapy+/-insulin or biguanide. Logistic regression models were used to investigate how well C-peptide levels predicted the subjects belonging to Group C who are likely to require insulin. The mean FCP and mean GSCP levels of Group C were significantly lower than in the other groups (p=0.024; p= <0.001 respectively). A GSCP cut-off value of < or =1.3 ng/mL predicted membership of Group C with 85% sensitivity and 89% specificity while a cut-off of < or =1.8 ng/mL was associated with 91% sensitivity and 66% specificity. In resource-poor settings where inadequate treatment are common, estimation of GSCP may be useful in predicting treatment response and should be weighed against the cost of inadequate therapy with higher morbidity and mortality.

Blood Glucose↗

PubMed2005

Prevalence of and risk factors for non-compliance with glove utilization and hand hygiene among obstetrics and gynaecology workers in rural China.

This study identified the prevalence of and risk factors for non-compliance with glove utilization and hand hygiene among rural obstetrics and gynaecology workers in two poor counties in Anhui, China. A cross-sectional survey was conducted using a self-administered anonymous semi-structured questionnaire. The study population included all health workers in the departments of obstetrics and gynaecology in township hospitals and county health facilities. Among the 137 participants, the rate of non-compliance with glove utilization was 61%, the rate of non-compliance with hand hygiene was 40%, and the rate of non-compliance with both was 67%. 'Unnecessary and inconvenient' accounted for 66% of the reasons for not always using gloves and 71% for not always washing hands. 'Short of gloves or water' accounted for 15% and 22% of reasons, respectively. Two variables were associated with non-compliance: county [odds ratio (OR)=11.56, P<0.001] and knowledge (OR=0.10, P=0.033). After removing county from the regression model, institutional level (OR=2.34, P=0.059), institutional support (OR=3.85, P=0.009) and knowledge (OR=0.05, P=0.007) were associated with non-compliance. The prevalence of non-compliance with glove utilization and hand hygiene was high. The risk factors for non-compliance were institutional level, institutional support and knowledge. These variables incorporated both subjective and objective reasons for non-compliance.

Adult↗

PubMed2005

The contribution of peripheral 5-hydroxytryptamine2A receptor to carrageenan-evoked hyperalgesia, inflammation and spinal Fos protein expression in the rat.

The present study was conducted to test the hypothesis that the peripheral 5-hydroxytryptamine (5-HT)2A receptor is involved in inflammatory hyperalgesia and production of noxious stimulus-induced neuronal activity at the level of the spinal cord dorsal horn. Intraplantar (i.pl.) injection of carrageenan dramatically reduced paw withdrawal latency to noxious heat (47 degrees C) and caused paw swelling. Pretreatment with ketanserin, a selective antagonist of 5-HT2A receptor, in the hindpaw produced dose-dependent inhibition of the hyperalgesia (0.5, 3 and 5 mug; i.pl.) with full relief at 5 mug. The drug also moderately reduced carrageenan-induced paw swelling in a dose-dependent manner. Carrageenan induced conspicuous expression of c-fos-like immunoreactivity (FLI) in the spinal dorsal horn of segments L4-5. Ketanserin (5 mug) markedly reduced carrageenan-induced FLI in all laminae of the dorsal horn. However, blockade of peripheral 5-HT1A receptors by (N-2-[4-(2-methoxyphenyl-1-piperazinyl] ethyl]-N-2-pyridinylcyclohexanecarboxamide at maximally effective doses (30 and 100 mug; i.pl.) did not alter carrageenan-induced hyperalgesia, edema or expression of FLI. The present study provided evidence at cellular level that the peripheral 5-HT2A receptor is preferentially involved in the development of thermal hyperalgesia in the carrageenan model of inflammation.

Animals↗

PubMed2005

Cyclooxygenase-2 inhibitors suppress angiogenesis and growth of gastric cancer xenografts.

Many researches have confirmed the tumor-prophylactic effects of cyclooxygenase-2 (COX-2) inhibitors. We previously observed their anti-cancer effects in vivo in nude mice and found that sulindac, a traditional non-steroidal anti-inflammatory drug (NSAID), and celecoxib, a selective COX-2 inhibitor, depressed the growth of SGC7901 xenografts via altering cell kinetics. Then we deeply studied the relationship between the two drugs and angiogenesis in gastric cancer. The results showed both sulindac and celecoxib decreased the micro-vessel density (MVD), which was labeled by either CD34 or VWF staining, within xenografts. Expression of both vascular endothelial growth factor (VEGF) and FGF-1 was suppressed. In addition, a positive correlation between MVD and the volume of SGC7901 xenografts was found. The effect of selective COX-2 inhibitor was stronger than non-special one despite of the insignificant difference. These results demonstrate that COX-2 plays an important role in angiogenesis of cancer. Apart from interfering cell kinetics, decreasing the expression of angiogenic factors and then inhibiting tumor angiogenesis could also be one of the mechanisms that COX-2 inhibitors suppress the growth of gastric cancer. These findings offer another theory basis for the future clinical application of NSAIDs against cancer.

Angiogenesis Inhibitors↗

PubMed2005

Low-dose methotrexate for the treatment of graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

Methotrexate (MTX) is commonly used in the prophylaxis of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). In order to evaluate the efficacy and safety of low-dose MTX treatment in patients with GVHD after allo-HSCT, 38 patients with acute GVHD (aGVHD), chronic GVHD (cGVHD) or GVHD post-donor lymphocyte infusion (post-DLI GVHD) after allo-HSCT received intravenous MTX at a dose of 5 or 10 mg every 5-- days until a complete or partial response was seen, or there was treatment failure or intolerable side effects. The overall response rate was 94.7% (18/19 patients) in patients with aGVHD, 76.2% (16/21 patients) in patients with cGVHD and 2/2 in patients with post-DLI GVHD. The response rate for GVHD involving various organs was 100% in skin, 75% in gut, 55.6% in liver, 75% in mouth and 100% in the eye, among all enrolled patients. Side effects were minor. Short-term, low-dose MTX is a tolerable and an effective regimen for patients with aGVHD, cGVHD or post-DLI GVHD after allo-HSCT.

Acute Disease↗

PubMed2005

Adeno-associated virus-mediated gene transfer of the heart/muscle adenine nucleotide translocator (ANT) in mouse.

Mitochondrial myopathy, associated with muscle weakness and progressive external ophthalmoplegia, is caused by mutations in mitochondria oxidative phosphorylation genes including the heart-muscle isoform of the mitochondrial adenine nucleotide translocator (ANT1). To develop therapies for mitochondrial disease, we have prepared a recombinant adeno-associated viral vector (rAAV) carrying the mouse Ant1 cDNA. This vector has been used to transduce muscle cells and muscle from Ant1 mutant mice, which manifest mitochondrial myopathy. AAV-ANT1 transduction resulted in long-term, stable expression of the Ant1 transgene in muscle precursor cells as well as differentiated muscle fibers. The transgene ANT1 protein was targeted to the mitochondrion, was inserted into the mitochondrial inner membrane, formed a functional ADP/ATP carrier, increased the mitochondrial export of ATP and reversed the histopathological changes associated with the mitochondrial myopathy. Thus, AAV transduction has the potential of providing symptomatic relief for the ophthalmoplegia and ptosis resulting from paralysis of the extraocular eye muscles cause by mutations in the Ant1 gene.

Adenine Nucleotide Translocator 1↗

PubMed2005

A genome-wide scan for quantitative trait loci linked to obesity phenotypes among West Africans.

OBJECTIVE: To identify quantitative trait loci (QTL) for three obesity phenotypes: body mass index (BMI), fat mass (FM) and percent body fat (PBF) in West Africans with type 2 diabetes (T2DM). DESIGN: An affected sibling pair (ASP) design, in which both siblings had T2DM. Obesity was analyzed as a quantitative trait using a variance components approach. SUBJECTS: Sib-pairs affected with T2DM from the Africa America Diabetes Mellitus (AADM) study, comprising 321 sibling pairs and 36 half-sibling pairs. MEASUREMENTS: Weight was measured on an electronic scale to the nearest 0.1 kg, and height was measured with a stadiometer to the nearest 0.1 cm. Body composition was estimated using bioelectric impedance analysis (BIA). Genotyping was carried out at the Center for Inherited Disease Research (CIDR) with a panel of 390 trinucleotide and tetranucleotide repeats. RESULTS: The obesity-related phenotype showing the strongest linkage evidence was PBF on chromosome 2 (LOD 3.30 at 72.6 cM, marker D2S739). Suggestive linkage to FM was found on chromosomes 2 (LOD 2.56 at 80.4 cM) and 5 (LOD 2.25 at 98 cM, marker D5S1725). The highest LOD score for BMI was 1.68 (chromosome 4, 113.8 cM). The areas of linkage for the three phenotypes showed some clustering as all three phenotypes were linked to the same regions of 2p13 and 5q14, and our study replicated linkage evidence for several regions previously reported in other studies. CONCLUSION: We obtained evidence for several QTLs on chromosome 2, 4 and 5 to three obesity phenotypes. This study provides data on the genetics of obesity in populations that are currently under represented in the global effort directed at understanding the pathophysiology of excess adiposity in free living individuals.

Adipose Tissue↗

PubMed2005

Studies on the drug release properties of nano-encapsulated indomethacin microparticles.

Indomethacin micro-crystals sized approximately 2 microm have been encapsulated with polyelectrolyte multi-layers for the purpose of controlled release. Charged linear poly (dimethyldiallyl ammonium chloride) (PDDA) and poly (styrene sulphonate) (PSS) were alternatively deposited on approximately 2 microm drug micro-crystals. The release of indomethacin from coated micro-crystals was measured in aqueous solutions of pH 1.4 and 6.8. The polyelectrolyte multi-layer capsule thickness was proved to control. The results provided a method of achieving prolonged drug release through self-assembly of polymeric shells on drug microcrystals.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

The reported incidence of work-related ill-health in Scotland (2002-2003).

BACKGROUND: Although incidence data for work-related ill-health in the UK are available, more detailed information for smaller geographical areas has hitherto been unpublished. AIMS: To estimate the incidence of work-related ill-health reported by clinical specialists in Scotland, 2002-2003. METHODS: THOR (The Health and Occupation Reporting network) is a UK wide reporting scheme for work-related ill-health. In 2002-2003, 241 out of 2162 physicians in THOR were based in Scotland. We have summarized the reported cases and calculated incidence rates for categories of ill-health by age, gender and industry. The UK Labour Force Survey (2002) was used to provide denominator data, with comparisons made between rates for Scotland and the rest of the UK. RESULTS: In 2002-2003, 4043 estimated cases were reported from Scotland. Mental ill-health was most frequently reported (41%); followed by musculoskeletal disorders (31%), skin disorders (16%), respiratory disease (10%), hearing disorders (2%) and infection (1%). The reported average annual incidence rate per 100,000 employees for all work-related ill-health in Scotland was 86.0. The highest reported rate for mental ill-health was found for employees in public administration and defence (76.7 per 100,000), and health and social work (72.3 per 100,000). The construction industry had the highest reported rate of musculoskeletal disorders (41.6 per 100,000), while hairdressers appeared at most risk of developing occupational contact dermatitis (rate=86.4 per 100,000). CONCLUSIONS: Despite its limitations, THOR has indicated types of work-related ill-health and related industries for targeted disease prevention in Scotland.

Adolescent↗

PubMed2005

Work-related infectious disease reported to the Occupational Disease Intelligence Network and The Health and Occupation Reporting network in the UK (2000-2003).

BACKGROUND: Infectious diseases remain an important cause of self-reported work-related illness, with socio-economic consequences, including sickness absence. Reporting of infectious disease by occupational and specialist physicians is an important tool in the investigation of occupationally related infections and is relevant in their management. AIMS: To examine the reporting of cases of infectious disease by occupational and specialist physicians to schemes collecting data on occupational ill-health. METHODS: Cases of infectious disease reported by occupational and specialist physicians to the UK based schemes, Occupational Disease Intelligence Network (ODIN) and The Health and Occupation Reporting network (THOR), from 2000 to 2003 were analysed by reporting patterns, diagnosis, single case or outbreak reporting and industry. RESULTS: The total number of estimated cases of infectious disease reported to ODIN and THOR from 2000 to 2003 was 5606; 74.9% cases were diarrhoeal disease, and 11.1% scabies. The majority (81.4%) of cases were reported in SIDAW, where the participation rate for reporters was 55%. Reporting rates were much higher in OPRA, SWORD and EPIDERM (ranging from 86 to 96%). The most frequently reported industrial sectors were social care (39.5%) and health (29.4%); while the manufacture of chemical products contributed 4.3% overall, but 33.8% to estimated cases in OPRA. CONCLUSIONS: Despite limitations related to under reporting, the occupational and specialist physician schemes in ODIN and THOR provide data that may be used to look at patterns of case reporting for occupational ill-health, including infectious disease. The reporting schemes also provide an important means of alerting peers about potential novel causes, precipitating factors, or industrial sectors associated with occupational disease.

Communicable Diseases↗

PubMed2005

Physicians' beliefs in the assessment of work attribution when reporting musculoskeletal disorders.

BACKGROUND: There is considerable uncertainty about work-relatedness and musculoskeletal disorders in general, and it is also not clear how physicians decide whether work has caused a disorder in an individual patient. AIMS: To investigate physicians' beliefs about assessment of occupational attribution for work-related musculoskeletal disorders. METHODS: A questionnaire survey was sent to 526 occupational physicians and 248 rheumatologists on: characteristics of cases seen, assessment of work attribution, definition of work-relatedness and threshold for case reporting. Continuous variables were analysed by mean, standard deviation, an independent two-sample t-test and the Mann-Whitney test. Mean and median values were calculated and Spearman's rank test was applied to ranked data. RESULTS: Questionnaires were completed by 68% occupational physicians and 64% rheumatologists. Both groups of physicians believed that 'history of onset in relation to workplace changes' and 'symptoms consistent with work exposure' were the most important factors suggesting work attribution. They considered that the most important objective of a reporting scheme was detection of trends in disease incidence and that the most suitable criteria for defining work-relatedness was the probability that exposure at work 'more likely than not' caused the condition (mean 0.73; SD=0.17), in a perceived likelihood scale (0-1). CONCLUSION: There was a strong agreement between occupational physicians and rheumatologists on questions about work-relatedness and musculoskeletal disorders. The level of probability for concluding work-relatedness has been quantified.

Attitude of Health Personnel↗

PubMed2005

Three-dimensional shielding calculations for the IFMIF neutron source using a coupled Monte Carlo/Deterministic computational scheme.

Shielding calculations for the International Fusion Materials Irradiation Facility (IFMIF) are complicated due to the geometrical complexity of the target system and the large-scale bulk shields around the source target. Three-dimensional shielding calculations were performed by using a newly developed Monte Carlo/Deterministic computational scheme. The neutron-photon fluxes and dose rate distributions in the back wall of the Test Cell and the access/maintenance room are presented and compared with previous shielding calculations. The results demonstrate that this coupled scheme is an useful computational tool for three-dimensional shielding analyses of complex and large nuclear facilities.

Computer Simulation↗

PubMed2005

Statistics on cancer in China: cancer registration in 2002.

The objective of this study was to determine how many population-based cancer registries exist in China, what methods are being used, and the statistical data that are available from them, and to identify future needs with respect to technical support. A two-stage survey was conducted in 2002 at provincial and cancer registry level. Based on the questionnaire used in these two stages, the basic distribution and descriptive information on population-based cancer registry practices in China are addressed. There are 48 cancer registries in China, covering 73 million people (5.7% of the total population of China in 2000). The oldest three registries are LinZhou, ShangHai and QiDong. There are marked variations in practice between registries, with respect to data collection, data management and coding. Differences are also found in administrative aspects and sources of financial support. In conclusion, this first national survey of Chinese cancer registry practice provides a benchmark against which development and standardization can be evaluated in the future. The survey suggests that lack of qualified personnel, insufficient funding support and lack of stability of the population are major problems in carrying out registration work in China. It also indicates several ways in which registry practice, and hence availability and quality of incidence and survival data can be improved.

Benchmarking↗

PubMed2005

Characterization of ultrafine coal fly ash particles by energy-filtered TEM.

In this study, energy-filtered transmission electron microscopy is demonstrated to be a valuable tool for characterizing ultrafine coal fly ash particles, especially those particles encapsulated in or associated with carbon. By examining a series of elemental maps (K-edge maps of C and O, and L-edge maps of Si, Al, Ti and Fe) recorded using the three-window method, considerable numbers of titanium and iron species with sizes from several nanometres to submicrometre were shown to be present, typically as oxides dispersed in the carbonaceous matrix. Crystalline phases, such as rutile and iron-rich oxide spinel, were also identified from electron diffraction patterns and high-resolution TEM images. Information about these ultrafine coal fly ash particles regarding their size, morphology, elemental composition and distribution, and crystalline phases, which has not been available previously in conventional ash studies, should be useful in toxicological studies and related environmental fields.

Air Pollutants↗

PubMed2005

Activation and function of hepatic NK cells in hepatitis B infection: an underinvestigated innate immune response.

Natural killer (NK) cells are abundant in the normal liver, accounting for around one-third of intrahepatic lymphocytes and are important in the defence against hepatitis B virus (HBV) infection as innate immune responses. In this review, we discuss the mechanisms of hepatic NK cell activity against HBV. Whether directly activated by HBV infection or indirectly activated by other lymphocytes such as NKT cells or antigen-presenting cells (APCs), hepatic NK cells exert their anti-viral functions by natural cytotoxicity and production of high levels of cytokines. However, activated NK cells play an important role in regulating adaptive immune responses by interaction with other lymphocytes such as T, B and APCs. In addition, NK cells may contribute to the lymphocyte-mediated liver injury during HBV infection that was previously considered to be mediated only by CD8+ T cells or/and NKT cells.

Animals↗

PubMed2005

Identification of a novel HLA-A allele HLA-A*2451 in a Chinese donor.

A novel human leucocyte antigen-A (HLA-A) allele, A*2451, has been identified during routine sequence-specific oligonucleotide typing and sequence-based typing of a sample from a registered donor of the Chinese Marrow Donor Program. The A*2451 allele differs from the closest matching allele A*2415 by one nucleotide substitution in exon 3, nt 363 G-->A, resulting in an amino acid change from M ATG to I ATA at codon 121.

Alleles↗

PubMed2005

Durancin L28-1A, a new bacteriocin from Enterococcus durans L28-1, isolated from soil.

AIMS: To isolate, characterize and identify bacteriocins from lactic acid bacteria in soil. METHODS AND RESULTS: Thirty-four acid-producing bacteria were isolated from 87 soil samples. Antibacterial activities were detected, and one strain, L28-1 produced a bacteriocin that was active against some Gram-positive bacteria. L28-1 was identified as Enterococcus durans by 16S rDNA sequence analysis and API50CHL. This bacteriocin did not lose its activity after autoclaving (121 degrees C for 15 min), but was inactivated by protease K. The bacteriocin was purified by hydrophobic column chromatography, and Sep-Pak C(18). Tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the partially purified bacteriocin contained numerous protein bands. Two bands that displayed antibacterial activities were c. 3.4 and 2.5 kDa in size. In this work, the 3.4-kDa bacteriocin was analysed with N-terminal amino acid and DNA sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis. The results indicated that the 3.4-kDa bacteriocin of Ent. durans L28-1 is a new natural enterocin variant. CONCLUSIONS: Enterococcus durans L28-1 produced a new bacteriocin. SIGNIFICANCE AND IMPACT OF THE STUDY: This study reports a novel bacteriocin that is produced by Ent. durans that has potential for use as a food preservative.

Amino Acid Sequence↗