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Biomedical subjects

Q Zhang

Publications and source records attributed to Q Zhang.

At least 37 records · Page 2Linked to original sources
PubMed2006

Expression of elevated levels of pro-inflammatory cytokines in SARS-CoV-infected ACE2+ cells in SARS patients: relation to the acute lung injury and pathogenesis of SARS.

The authors have previously shown that acute lung injury (ALI) produces a wide spectrum of pathological processes in patients who die of severe acute respiratory syndrome (SARS) and that the SARS coronavirus (SARS-CoV) nucleoprotein is detectable in the lungs, and other organs and tissues, in these patients. In the present study, immunohistochemistry (IHC) and in situ hybridization (ISH) assays were used to analyse the expression of angiotensin-converting enzyme 2 (ACE2), SARS-CoV spike (S) protein, and some pro-inflammatory cytokines (PICs) including MCP-1, TGF-beta1, TNF-alpha, IL-1beta, and IL-6 in autopsy tissues from four patients who died of SARS. SARS-CoV S protein and its RNA were only detected in ACE2+ cells in the lungs and other organs, indicating that ACE2-expressing cells are the primary targets for SARS-CoV infection in vivo in humans. High levels of PICs were expressed in the SARS-CoV-infected ACE2+ cells, but not in the uninfected cells. These results suggest that cells infected by SARS-CoV produce elevated levels of PICs which may cause immuno-mediated damage to the lungs and other organs, resulting in ALI and, subsequently, multi-organ dysfunction. Therefore application of PIC antagonists may reduce the severity and mortality of SARS.

Acute Disease↗
PubMed2006

Iron sucrose augments homocysteine-induced endothelial dysfunction in normal subjects.

Intravenous iron is commonly used in conjunction with erythropoietic agents to treat anemia in patients with chronic kidney disease. Iron has been proposed to promote oxidative stress and endothelial dysfunction in vascular tissues. We studied the acute effects of intravenous iron sucrose on homocysteine-induced endothelial dysfunction in the brachial artery of normal human subjects. In all, 40 healthy subjects received intravenous iron sucrose 100 mg or placebo over 30 min immediately before ingestion of 100 mg/kg of oral methionine in a double-blind, randomized study. Flow- and nitroglycerin-mediated dilation in the brachial artery, serum markers of iron stores, and homocysteine and nitrotyrosine levels were measured before and after study drug administration. Intravenous iron significantly increased transferrin saturation and non-transferrin-bound iron (NTBI) when compared with placebo. Flow-mediated dilation significantly decreased from baseline 1 h after administration of iron sucrose when compared with placebo (from 6.66+/-0.47 to 1.93+/-0.35% after iron sucrose vs from 6.00+/-0.40 to 5.61+/-0.46% after placebo, P<0.001), but did not differ between groups at 4 h (1.10+/-0.39 vs 1.33+/-0.51%). Nitroglycerin-mediated vasodilation, and homocysteine and 3-nitrotyrosine levels did not differ after administration of iron sucrose and placebo. Intravenous administration of iron sucrose in the setting of transient hyperhomocysteinemia induced by methionine ingestion significantly increased transferrin saturation and plasma levels of NTBI and significantly attenuated flow-mediated dilation in the brachial artery when compared with placebo. This potential mechanistic link between intravenous iron and endothelial dysfunction warrants further study of cardiovascular effects of intravenous iron in anemic chronic kidney disease populations.

Adult↗
PubMed2006

Effect of stealthy liposomal topotecan plus amlodipine on the multidrug-resistant leukaemia cells in vitro and xenograft in mice.

BACKGROUND: Multidrug resistance (MDR) is a major obstacle to successful cancer chemotherapy as the over-expressed MDR protein acts as an efflux pump, which leads to a reduction in the uptake of the anticancer agent by tumour cells. We combined topotecan and amlodipine together into the stealthy liposomes, in which amlodipine was applied as a MDR reversing agent to overcome the resistance. MATERIALS AND METHODS: Cytotoxicity, apoptosis and the signalling pathway assays were performed on human chronic myelogenous leukaemia K562, promyelocytic leukaemia HL-60 and MDR HL-60 cells, respectively. Pharmacokinetics and antitumour activity studies were performed on normal Kunming mice and female BALB/c nude mice with MDR HL-60 xenografts, respectively. RESULTS: Topotecan alone was effective in inhibiting the growth of non-resistant leukaemia cells, K562 and HL-60 cells but not the growth of MDR HL-60 cells. The resistance of topotecan in MDR HL-60 cells was potently reversed by the addition of amlodipine. Moreover, amlodipine enhanced the apoptosis-inducing effect of topotecan synergistically. Apoptosis was through activating caspases in a cascade: first, the initiator caspase 8 and then effectors caspase 3/7 (total activity of caspases 3 and 7) were activated. Being encapsulated into the stealthy liposomes with an acidic internal medium, topotecan existed dominantly in an active lactone species, which was reversibly changed from an inactive carboxylate form via a pH-dependent reaction. After administration of stealthy liposomes to mice, the blood exposure of the lactone form was evidently increased and extended. The antitumour effects in the MDR HL-60 xenografted tumour were stealthy liposomal topotecan (SLT) plus amlodipine > SLT > un-encapsulated topotecan > blank control. CONCLUSIONS: The enhanced antitumour activity in the MDR HL-60 cells by the SLT plus amlodipine could be owing to multiple reasons: (a) synergistic apoptosis inducing effect, (b) reversing MDR by amlodipine and (c) increasing the availability of active lactone of topotecan by the stealthy liposomes. The apoptosis induced by amlodipine is through caspase 8 and then the 3/7 signalling pathway.

Amlodipine↗
PubMed2006

Comparison of esophageal acid exposure at 1 cm and 6 cm above the squamocolumnar junction using the Bravo pH monitoring system.

The aim of this study was to assess the quantitative differences of acid exposure at 1 cm and 6 cm above the squamocolumnar junction (SCJ) using two radiotelemetry pH capsules affixed to the esophageal mucosa. Ten normal subjects and 10 endoscopy-negative gastroesophageal reflux disease (GERD) patients without hiatus hernia (ages 20-54, 12 male) were studied for a 24-h period using the Bravo pH monitoring system. pH capsules were placed 1 cm and 6 cm above the SCJ. Interpretable data for at least 14 h was obtained in 18 of the 20 subjects (9 normal, 9 GERD). Two failures occurred secondary to early capsule dislodgement. Median esophageal acid exposure was significantly increased at 1 cm above the SCJ compared to 6 cm above the SCJ during the total, upright and postprandial time periods in both normal and GERD subjects. During a 2 h postprandial period the esophageal acid exposure was 8-fold greater in GERD subjects and 5-fold greater in normal subjects 1 cm above the SCJ compared to 6 cm above the SCJ. Confident measurement of esophageal acid exposure at a fixed position 1 cm above the SCJ is feasible with the Bravo system. Acid exposure was significantly higher 1 cm above the SCJ compared to 6 cm above the SCJ in both GERD patients and controls. These findings suggest that measurement of acid exposure 1 cm above the SCJ may improve accuracy of pH monitoring by detecting acid reflux events confined to the distal esophagus.

Adult↗
PubMed2006

Evaluation of the CLSI cefoxitin 30-microg disk-diffusion method for detecting methicillin resistance in staphylococci.

Methicillin susceptibility of 415 staphylococcal isolates from Chinese hospitals was assessed using the CLSI disk-diffusion method with a cefoxitin 30-microg disk in comparison with an oxacillin 1-microg disk. PCR-based detection of mecA was the reference standard. The cefoxitin 30-microg disk performed with almost the same high level of accuracy as the oxacillin 1-microg disk in detecting methicillin resistance in Staphylococcus aureus. For coagulase-negative staphylococci (CoNS), the sensitivity of the cefoxitin 30-microg disk was 90.5%, compared with 83.4% for the oxacillin 1-microg disk. Confirmatory testing of isolates with borderline susceptibility and revision of the cefoxitin breakpoint are proposed in order to categorise CoNS more accurately.

Anti-Bacterial Agents↗
PubMed2006

Phosphorylated S6 ribosomal protein: a novel biomarker of antibody-mediated rejection in heart allografts.

We tested the hypothesis that phosphorylation of S6 ribosomal protein (S6RP), a downstream target of the PI3K/Akt/mTOR pathway, is a biomarker of antibody-mediated rejection (AMR) in heart allografts. Primary cultures of human aortic and microvascular endothelial cells (EC) were treated with anti-HLA class I and class II antibodies (Ab) and cell lysates were studied for phosphorylation of S6 ribosmal protein at Serine235/236 (p-S6RP). Treatment of cultured EC with anti-class I and class II Ab stimulated S6RP phosphorylation. Immunohistochemical techniques were used to detect the level of p-S6RP in endomyocardial biopsies (n = 131) from 46 heart transplant recipients and the results were correlated with histopathological diagnosis of rejection, C4d staining, production of posttransplant anti-HLA Ab and clinical outcome. Increased phosphorylation of S6RP in endomyocardial biopsies was significantly associated with the diagnosis of AMR (p < 0.0001). No significant association between acute cellular rejection (ACR) and p-S6RP was observed. C4d staining was positively associated with both AMR and p-S6RP. Posttransplant anti-HLA class II Ab production was also significantly associated with a positive p-S6RP status in cardiac biopsies. These results indicate that p-S6RP is a useful biomarker for the diagnosis of AMR.

Acute Disease↗
PubMed2006

Novel locus for X linked recessive high myopia maps to Xq23-q25 but outside MYP1.

BACKGROUND: High myopia is a common genetic variation in most cases, affecting 1-2% of people, and is the fourth most common disorder causing blindness worldwide. Six autosomal dominant loci and one X-linked recessive locus have been reported, but no genes responsible for high myopia have been identified. OBJECTIVE: To report a Chinese family in which six males presented with high myopia consistent with an X linked recessive trait. RESULTS: Affected individuals shared three common features: high myopia, reduced visual acuity, and fundal changes of high myopia. Protan and deutan were observed in the family, but they did not co-segregate with the high myopia phenotype. X-chromosome-wide linkage analysis mapped the high myopia locus to a 25 cM (14.9 Mb) region on Xq23-q25 between DXS1210 and DXS8057, with maximum two point lod scores at theta = 0 of 2.75 and 2.29 for DXS1001 and DXS8059, respectively. CONCLUSIONS: This new myopia locus is outside the linked region of the first high myopia locus (MYP1). Refinement of the linkage region with additional families and screening candidate genes for mutation may lead to the identification of the defect gene.

Adult↗
PubMed2006

Caries-inhibiting effect of chlorhexidine varnish in pits and fissures.

Evidence regarding the caries-inhibiting effect of chlorhexidine varnish is inconclusive. This study investigated the caries-inhibiting effect of the varnish EC40 on pits and fissures of first permanent molars. A two-year randomized controlled trial was carried out among 461 six- to seven-year-old children. In a split-mouth design, one group of molars received EC40 at baseline, 6, 12, and 18 months, and another group at baseline, 3, 12, and 15 months. Control molars did not receive EC40. Adherence to the treatment protocol was good. The dropout rate was 17%. Blinded examiners performed dental examinations. The caries-inhibiting effects of the two EC40 application schemes were comparable. The prevented fraction of caries was 25% (95%CI, 1%, 49%, p = 0.04) after 2 years and 9% (95%CI, -11%, 29%, p = 0.20) one year after termination of the trial, suggesting a short-term benefit from the use of EC40. The efficiency of EC40 is questionable in low-caries-incidence child populations.

Anti-Infective Agents, Local↗
PubMed2006

Detection of quantitative trait loci affecting milk production traits on bovine chromosome 6 in a Chinese Holstein population by the daughter design.

Fourteen microsatellite markers with a coverage of 63.5 cM on bovine chromosome 6 were selected, and 26 sire families with 2,260 daughters were analyzed for mapping quantitative trait loci (QTL) affecting 5 milk production traits in a Chinese Holstein population. In the analyses across 26 families and within the largest significant families with a one-QTL model fitted, a QTL near BMS470 was detected that affected fat yield at the 5% experiment-wide significance level. When a 2-QTL model was fitted in the across-family analysis, it was found that there might exist 2 QTL affecting the 3 yield traits, although the exact or empirical thresholds for the significance testing were unknown. In all analyses, the results for milk yield and protein yield were generally consistent, which might have resulted from the same genetic background for milk and protein yield.

Animals↗
PubMed2006

[Distribution of hepatitis B virus genotypes in Guizhou and analysis of clinical significance.].

BACKGROUND: To investigate the distribution of HBV genotypes in Guizhou and study the relationship between the genotype and the progression of liver disease. METHOD: Totally 693 patients with chronic HBV infection, from 4 areas of Guizhou, including 292 asymptomatic HBV carriers (ASC), 276 cases with chronic hepatitis (CH), 76 liver cirrhosis (LC), 49 hepatocellular carcinoma (HCC) were examined. The HBV genotype was determined by restriction fragment length polymorphism analysis and the relationship between HBV genotype and the progression of liver disease was studied by multifactor analysis such as HBsAg positivity, HBV DNA load and ALT level. RESULTS: Of the 693 patients, 6 (0.87%), 449 (64.79%), 233 (33.62%), and 5 (0.72%) belonged to genotype A, B, C and D, respectively. There was a statistically siganificant difference in the distribution of genotype B among Kaili (96.4%), Zunye (78.79%), Duyun (76.19%) and Guiyang (53.66%) areas (P less than 0.01). Genotype C was more prevalent in Guiyang than in other three areas (45.68% vs. 23.8%, 45.68% vs. 13.13%, 45.68% vs. 3.96%, P less than 0.01, respectively). There were also statistically significant difference in distribution of genotype B and C in various stages of liver disease (P less than 0.01). Genotype B showed a decreasing trend from ASC, CH, LC to HCC and genotype C was more frequent in patients with CH (45.92%) than in those with ASC (20.6%), LC (17.17%) and HCC (16.31%). The ALT levels and the mean ages were significantly higher and older in patients with genotype C than those in genotype B. The HBeAg positivity was significantly lower in genotype C than that in genotype B (48.07% vs 61.90%, P less than 0.01). CONCLUSION: Genotype A, B, C and D exist in Guizhou. Genotype B predominates and genotype C was the second common. The geographic distribution of genotype B and C are different in some areas of Guizhou. Compared with genotype B, genotype C is associated with the development of more severe liver damage.

China↗
PubMed2005

Tumor suppressor pp32 represses cell growth through inhibition of transcription by blocking acetylation and phosphorylation of histone H3 and initiating its proapoptotic activity.

pp32 belongs to a family of leucine-rich acidic nuclear proteins, which play important roles in many cellular processes including regulation of chromatin remodeling, transcription, RNA transport, transformation and apoptosis. pp32 is described as a new tumor suppressor. It is unknown as to how pp32 works in tumor suppression. We found that overexpression of pp32 in human Jurkat T cells inhibits cell growth, and silenced pp32 promotes growth. We first showed that hyperacetylation and hyperphosphorylation of histone H3 are required for T-cell activation. Phosphorylation of histone H3 precedes acetylation during T-cell activation. pp32 specifically binds to histone H3 and blocks its acetylation and phosphorylation. pp32 directly initiates caspase activity and also promotes granzyme A-mediated caspase-independent cell death. Taken together, pp32 plays a repressive role by inhibiting transcription and triggering apoptosis.

Acetylation↗
PubMed2005

Multi-gene epigenetic silencing of tumor suppressor genes in T-cell lymphoma cells; delayed expression of the p16 protein upon reversal of the silencing.

To understand better T-cell lymphomagenesis, we examined promoter CpG methylation and mRNA expression of closely related genes encoding p16, p15, and p14 tumor suppressor genes in cultured malignant T-cells that were derived from cutaneous, adult type, and anaplastic lymphoma kinase (ALK)-expressing T-cell lymphomas. p16 gene was epigenetically silenced in all but one of the 10 malignant T-cell lines examined, p15 gene silenced in roughly half of the lines, and p14 was the least frequently affected. Extensive methylation of the p16 promoter was seen in six out of 10 cutaneous T-cell lymphoma patient samples and corresponded with lack of p16 protein expression in the cases examined. Treatment of cultured T-cells with the DNA methyltransferase inhibitor, 5-aza-2-deoxy-cytidine, resulted in reversal of the p16 gene silencing. However, expression of p16 protein was delayed in relationship to p16 promoter demethylation and required up to 3 weeks to occur, seemingly reflecting late activation of the p16 gene. These findings indicate that epigenetic silencing affects in T-cell malignancies, often simultaneously, several tumor suppressor genes that impact on key cell functions. The observed differential silencing of p16 and p14, and to a lesser degree p15 gene, indicates that the silencing is governed by precise, promoter region-specific mechanisms. The study provides also further rationale for treatment of at least some types of T-cell lymphomas with DNA methyltransferase inhibitors to target the epigenetically silenced tumor suppressor genes.

Adult↗
PubMed2005

Assessment of PCBs and PCDD/Fs along the Chinese Bohai Sea coastline using mollusks as bioindicators.

Mollusk samples such as bivalves and gastropods were collected from eight sampling sites along Bohai Sea coastline from northeastern China. The samples were analyzed for polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC-HRMS) to elucidate bioaccumulation of persistent organic pollutants in benthon. Residue levels of sigmaPCBs and sigmaPCDD/Fs were in the ranges of 66.1 to 583.6 ng/g and 0.9 to 15317 pg/g on a lipid-weight basis, respectively, The pollution source was identified using principal component analysis (PCA) in some coastal areas. It indicated that the typical pollution sources were characterized by PCB3, which was one Chinese technical product of PCBs. PCA also revealed the similarity patterns of PCBs between identical species collected from the different sites. The higher gastropod PCB concentrations were related to a former capacitor factory and the paint factories in some coastal areas, but this was not the case with the bivalves. The results of this study suggest that some gastropod species may be a potential bioindicator or "sentinel" organism for marine PCBs monitoring.

Animals↗
PubMed2005

Predicting gas chromatographic retention times of 209 polybrominated diphenyls (PBBs) for different temperature programs.

A method has been developed to predict the retention times of 209 individual polybrominated diphenyl congeners for different temperature programs. The retention equations lnk'=A+B/T of five PBBs in gas chromatography (GC) were used to evaluate the properties of the regression coefficients A and B, which are widely accepted as being highly reliable chromatographic retentions. The quantitative relationships between the A and B values of PCBs and those of PBBs were found. The regression equations derived have coefficients of determination greater than 0.999. The A, B values of any PBB can be predicted by using the A, B values of the PCB according to these relationships. Using these predicted A and B values, the retention times of all PBBs can be predicted. This is an important advance in the identification of PBBs because at present there are only a few PBB standards available.

Chromatography, Gas↗
PubMed2005

Acid reflux event detection using the Bravo wireless versus the Slimline catheter pH systems: why are the numbers so different?

OBJECTIVE: This study analysed the relative accuracy of the Bravo wireless and the Slimline catheter-Mark III Digitrapper pH systems in the detection of acid reflux events. METHODS: Twenty five asymptomatic subjects were studied. A Bravo capsule was placed 6 cm above the squamocolumnar junction (SCJ), marked by an endoclip, and a Slimline pH catheter was placed 5 cm above the manometrically localised lower oesophageal sphincter. The distance between the SCJ and each pH electrode was measured fluoroscopically. An in vivo pH reference was established using swallows of orange juice (pH 3.88). Concurrent pH data from the two systems were analysed in Excel spreadsheets. RESULTS: Significantly more acid reflux events were reported by the Digitrapper system than the Bravo system (117.0 v 41.8). This was not explained by electrode position as there was no difference in median distance between the SCJ and either pH electrode (7.25 cm v 7.08 cm). The dominant source of discrepancy between systems was inaccuracy in electrode calibration and, after adjustment using the in vivo orange juice pH measurement, the discrepancy improved by 40%. However, discrepancy still existed and was most pronounced with short reflux events (1-15 s for the catheter, 1-17 s for the Bravo) associated with minimal intraoesophageal acidity and poor concordance between systems. CONCLUSION: Substantially more reflux events were reported by the Digitrapper system compared with the Bravo system; 40% of excess events were attributable to a flawed software scheme for electrode thermal calibration while most of the remainder were brief events with poor reproducibility between systems.

Adult↗
PubMed2005

Localization of pms3, a gene for photoperiod-sensitive genic male sterility, to a 28.4-kb DNA fragment.

Photoperiod-sensitive genic male-sterile (PSGMS) rice, in which pollen fertility is regulated by day-length, originally arose as a natural mutant in the rice cultivar Nongken 58 (Oryza sativa ssp. japonica). Previous studies identified pms3 on chromosome 12 as the locus of the original PSGMS mutation. In this study we have assigned the pms3 locus to a 28.4-kb DNA fragment by genetic and physical mapping. A cross between Nongken 58S (PSGMS line) and DH80 was used to produce an F2 population of about 7000 plants, from which 892 highly sterile individuals were obtained for recombination analysis. By analyzing recombination events in the sterile individuals using a total of 157 RFLP probes from a BAC contig covering the pms3 region, the pms3 locus was localized to a sub-region of less than 1.7 cM. Further analysis of recombination events using 49 additional probes isolated from this sub-region identified markers flanking the pms3 region on each side; these markers are only 28.4-kb apart. Sequence analysis of this fragment predicted the presence of five ORFs, found high homology with two ESTs in public databases, and detected three SNPs between the mutant and the wild-type parents, which may be helpful for identifying a candidate gene for pms3.

Chromosome Mapping↗
PubMed2005

Asthma-related resource use and cost by GINA classification of severity in three European countries.

BACKGROUND: This study assessed the relationship between asthma burden and asthma severity in France, Italy, and Spain. METHODS: Adult asthmatics, 18-55 years of age, completed a questionnaire while visiting a respiratory physician in 1998 and 1999. Asthma severity was categorized by physicians as intermittent, mild persistent, moderate persistent, or severe persistent according to Global Initiative for Asthma (GINA) guidelines. RESULTS: Totals of 282 patients in France, 500 in Italy, and 296 in Spain entered the study. There were few differences between the three countries in the asthma symptom burden. Most patients with persistent asthma had used inhaled corticosteroids in the previous 14 days. Unexpectedly, 35% (Italy) to 83% (Spain) of patients with intermittent asthma also had used inhaled corticosteroids. In Spain, visits to the emergency department were more frequent (OR 7.0, 95% CI 4.9-10.0 with Italy as reference) and the costs of emergency care in all asthma severity categories were up to 10 times higher than in Italy and France. The frequency of hospitalizations did not differ systematically between the three countries. CONCLUSIONS: Inadequate control of asthma symptoms among patients with severe persistent asthma could not be entirely explained by under-prescribing of asthma medications. The use of inhaled corticosteroids by patients with intermittent asthma might reflect misclassification of asthma severity, possibly due to difficulty in interpreting the GINA guidelines. The relatively high cost of emergency care in Spain does not appear to be related to greater asthma severity or poorer symptom control, but may be a feature of the Spanish health care system.

Adolescent↗