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Biomedical subjects

Q Zhou

Publications and source records attributed to Q Zhou.

At least 19 recordsLinked to original sources
PubMed2006

Impact assessment of cadmium contamination on rice (Oryza sativa L.) seedlings at molecular and population levels using multiple biomarkers.

Assessment of environmental contamination on ecology (plant) at molecular and population levels is important in risk quantification and remediation study. Random amplified polymorphic DNA (RAPD) assay and related other fingerprinting techniques have been employed to detect the genotoxin-induced DNA damage and mutations. This research compared the effects occurring at molecular and population levels in rice seedlings exposed to cadmium (Cd) concentrations of 15-60 mg l(-1) for 8 days with quartz sand culture. Inhibition of root growth and increase of total soluble protein content in root tips of rice seedlings were observed with the increase of Cd concentration. For the RAPD analyses, 12 RAPD primers of 50-70% GC content were found to produce unique polymorphic band patterns and subsequently were used to produce a total of 180 bands of 179-3056 bp in molecular size in the control root tips of rice seedlings. Results produced by these RAPD primers indicate that changes in RAPD profiles of root tips after Cd treatment include modifications in band intensity and gain or loss of bands by comparison with control. The effect of changes was dose-dependent. Genomic template stability compares favourably with the traditional indices such as root growth and soluble protein content. The DNA polymorphisms detected by RAPD analysis can be applied as a suitable biomarker assay for the detection of genotoxic effects of Cd contamination on plants.

Biomarkers↗
PubMed2006

An interpretation of potential scale dependence of the effective matrix diffusion coefficient.

Matrix diffusion is an important process for solute transport in fractured rock, and the matrix diffusion coefficient is a key parameter for describing this process. Previous studies have indicated that the effective matrix diffusion coefficient values, obtained from a large number of field tracer tests, are enhanced in comparison with local values and may increase with test scale. In this study, we have performed numerical experiments to investigate potential mechanisms behind possible scale-dependent behavior. The focus of the experiments is on solute transport in flow paths having geometries consistent with percolation theories and characterized by multiple local flow loops formed mainly by small-scale fractures. The water velocity distribution through a flow path was determined using discrete fracture network flow simulations, and solute transport was calculated using a previously derived impulse-response function and a particle-tracking scheme. Values for effective (or up-scaled) transport parameters were obtained by matching breakthrough curves from numerical experiments with an analytical solution for solute transport along a single fracture. Results indicate that a combination of local flow loops and the associated matrix diffusion process, together with scaling properties in flow path geometry, seems to be an important mechanism causing the observed scale dependence of the effective matrix diffusion coefficient (at a range of scales).

Diffusion↗
PubMed2006

A comparative approach to somatic cell nuclear transfer in the rhesus monkey.

BACKGROUND: Despite the potential utility of primate somatic cell nuclear transfer (SCNT) to biomedical research and to the production of autologous embryonic stem (ES) cells for cell- or tissue-based therapy, a reliable method for SCNT is not yet available. Employing the rhesus monkey as a clinically relevant animal model, we have compared a conventional electrofusion method for SCNT with a one-step micromanipulation (OSM) method. METHODS: A prospective, randomized trial was conducted using only oocytes that were mature [metaphase II (MII)] at collection and a fibroblast-like cell line as nuclear donor cells (fetal fibroblasts). The embryos produced were characterized for in vitro developmental potential, cell number, karyotype and expression of nuclear mitotic apparatus (NuMA) and OCT-4. RESULTS: An in vitro blastocyst development rate of 24.4% was achieved with the OSM method, significantly higher than the 12.2% obtained following electrofusion. SCNT-produced embryos expressed normal karyotypes, cell numbers and NuMA and OCT-4 proteins in most cases. SCNT with male nuclear donor cells resulted in the production of male, SCNT blastocysts, eliminating the possibility of a parthenogenetic origin. Of the four fibroblast cell lines tested as nuclear donor cells, two supported the routine production of blastocysts following SCNT. CONCLUSIONS: The application of a modified SCNT technique (OSM) followed by embryo culture in hamster embryo culture medium-10 (HECM-10) allows, for the first time, the routine production of SCNT blastocysts, most of which appear normal by immunochemical, cytochemical and in vitro developmental criteria. These embryos will provide a resource for isolating ES cells and for studies of nuclear reprogramming by monkey cytoplasts.

Animals↗
PubMed2006

Sensitive electrochemical enzyme immunoassay microdevice based on architecture of dual ring electrodes with a sensing cavity chamber.

A novel electrochemical detection architecture was investigated for enzyme immunoassay sensors. Microchips with dual-ring working and counter electrodes, and a sensing cavity chamber were made on glass slides. The glass surface of the microchip was coated by 3-aminopropyltriethoxysilane (APTES). Goat IgG, as a example, was covalently captured on APTES-modified glass surfaces through glutaraldehyde (GA) as a cross-linker. Enzyme substrate, p-aminophenyl phosphate (PAPP) was prepared by electrolysis. The enzyme conversion from home-synthetic PAPP to p-aminophenol (PAP) was examined by differential pulse voltammetry (DPV). A competitive inhibition enzyme-linked immunosorbant assay (ELISA) was designed to test the system. Experimental results demonstrate that a detection limit of 118 fg/ml of goat IgG and a dynamic range of 118 fg/ml to 1.18 ng/ml, up to five orders of magnitude could be achieved. Due to its novel architecture design and electronic detection scheme, the method can be used to fabricate portable electrochemical ELISA lab-on-chip systems. The technology could have great potential in clinical diagnostic applications.

Animals↗
PubMed2006

Intrahepatic upregulation of RhoA and Rho-kinase signalling contributes to increased hepatic vascular resistance in rats with secondary biliary cirrhosis.

BACKGROUND AND AIMS: Portal hypertension in cirrhosis is mediated in part by increased intrahepatic resistance, reflecting an increased sensitivity of the hepatic microvasculature to vasoconstrictors. Activation of the RhoA/Rho-kinase pathway is essential for contraction of vascular smooth muscle. The aim of this study was to investigate RhoA/Rho-kinase mediated regulation of the intrahepatic vascular tone in cirrhotic rats. METHODS: Cirrhosis was induced by bile duct ligation (BDL). Hepatic RhoA and Rho-kinase expressions were studied by real time reverse transcription polymerase chain reaction and western blot analysis. Hepatic Rho-kinase activity in rat and human livers was assessed as phosphorylation of the Rho-kinase substrate moesin. The effect of the Rho-kinase inhibitor Y-27632 on hepatic perfusion pressure was measured in livers perfused at constant flow. The in vivo effect of intravenous application of Y-27632 was studied by haemodynamic measurements. RESULTS: Hepatic expressions of RhoA and Rho-kinase were increased at mRNA and protein level in BDL rats. Intrahepatic moesin phosphorylation was increased in livers from cirrhotic rats and patients with alcohol induced cirrhosis. Y-27632 reduced the basal perfusion pressure of in situ perfused livers in BDL rats but not in sham operated rats. Y-27632 reduced the sensitivity to methoxamine in isolated perfused livers in sham operated rats more than in BDL rats. In vivo, Y-27632 reduced portal pressure to a greater extent in BDL rats than in sham operated rats. Intrahepatic vascular resistance was decreased in response to bolus injection of Y-27632 in BDL rats but not in sham operated rats. CONCLUSIONS: Upregulation of RhoA and Rho-kinase contributes to increased intrahepatic resistance in cirrhotic rats and to an increased sensitivity of cirrhotic livers to vasoconstrictors.

Animals↗
PubMed2006

An alternative to Portland Cement for waste encapsulation--the calcium sulfoaluminate cement system.

Currently, Portland Cement (PC) is used extensively in the solidification/stabilisation of a wide variety of wastes. In the nuclear industry, low and intermediate level radioactive wastes are encapsulated or immobilised within composite PC cement systems based on high replacement with blast furnace slag or fly ash. However, the high alkalinity of these PC-based systems will corrode reactive metals found in some wastes releasing hydrogen and forming expansive corrosion products. Alternative cement systems could provide a different hydration chemistry, which would allow wastes containing these metals to be encapsulated with lower reactivity. Calcium sulfoaluminate (CS A) cement is one such cement. It combines economy of cost and low emission of CO(2) with rapid strength gain and compatibility with other construction materials. Hydration provides an internal pore solution where the pH is considerably lower than that of PC. The main hydration product, ettringite, can incorporate a number of ions into its crystal structure, making it an ideal candidate for waste immobilisation. This paper details some results from a commercial CS A system that examines aspects of mixing, hydration of different formulations and aluminium corrosion behaviour. The fluidity of mixes can be adjusted by changing the formulations. All designed mixes were set within 24 h with little bleeding and the pH values were in the range of 10-11.5. In addition, a significant reduction in Al corrosion was observed compared to a composite OPC system. Although these results provide encouragement for the idea that CS A cement can provide a possible alternative to PC in the immobilisation of difficult and reactive wastes, further investigation is needed.

Aluminum↗
PubMed2006

Meta-analysis of flavonoids for the treatment of haemorrhoids.

BACKGROUND: The aim of the study was to evaluate the impact of flavonoids on those symptoms important to patients with symptomatic haemorrhoids. METHODS: A comprehensive search strategy was used. All published and unpublished randomized controlled trials comparing any type of flavonoid to placebo or no therapy in patients with symptomatic haemorrhoids were included. Two reviewers independently screened studies for inclusion, retrieved all potentially relevant studies and extracted data. RESULTS: Fourteen eligible trials randomized 1514 patients. Studies were of moderate quality and showed variability in the results with potential publication bias. Meta-analyses using random-effects models suggested that flavonoids decrease the risk of not improving or persisting symptoms by 58 per cent (relative risk (RR) 0.42 (95 per cent confidence interval (c.i.) 0.28 to 0.61)) and showed an apparent reduction in the risk of bleeding (RR 0.33 (95 per cent c.i. 0.19 to 0.57)), persistent pain (RR 0.35 (95 per cent c.i. 0.18 to 0.69)), itching (RR 0.65 (95 per cent c.i. 0.44 to 0.97)) and recurrence (RR 0.53 (95 per cent c.i. 0.41 to 0.69)). CONCLUSION: Limitations in methodological quality, heterogeneity and potential publication bias raise questions about the apparent beneficial effects of flavonoids in the treatment of haemorrhoids.

Female↗
PubMed2006

Comprehensive analysis of the factors for propionic acid accumulation in acidogenic phase of anaerobic process.

The accumulation of propionic acid in the anaerobic process often leads to a low efficiency of the methanogenic phase due to the low acetogenic rate of propionic acid, and hence the low wastewater treatment efficiency. Three acidogenic reactors were used to study the reasons for propionic acid accumulation in the acidogenic phase and its control strategy. The experimental results indicated that in the micro-aerobic circumstance (ORP>-100 mV) the accumulation of propionic acid in the acidogenic reactor always occurred at any pH value. Under strict anaerobic circumstances (ORP < -150 mV), typical propionic acid-type fermentation commonly occurred at pH about 5.5 regardless of ORP value. However, at pH about 5.0, either propionic acid-type or butyric acid-type fermentation might occur depending on whether ORP was high or low. Higher hydrogen production rate was found to have no direct relationship to the accumulation of propionic acid in the acidogenic reactors. In fact, great yield of NADH maybe the major reason for simultaneous accumulation of propionic acid and higher biohydrogen generation rate in the traditional anaerobic process. The highest biohydrogen generation rate occurred during the ethanol-type fermentation without the accumulation of propionic acid. Ethanol-type fermentation is a better choice when using an anaerobic acidogenic reactor of a two-phase separated anaerobic process to efficiently produce biohydrogen simultaneously with organic wastewater pre-treatment.

Bacteria, Anaerobic↗
PubMed2006

Central sensitisation in visceral pain disorders.

The concepts of visceral hyperalgesia and visceral hypersensitivity have been examined in a variety of functional gastrointestinal disorders (FGIDs). Although the pathophysiological mechanisms of pain and hypersensitivity in these disorders are still not well understood, exciting new developments in research have been made in the study of the brain-gut interactions involved in the FGIDs.

Brain↗
PubMed2006

Contribution of cell-surface components to Cu2+ adsorption by Pseudomonas putida 5-x.

The contribution of various cell-surface components to Cu2+ adsorption by a Gram-negative bacterium, Pseudomonas putida 5-x, that was isolated from local electroplating effluent with a high capability to accumulate heavy metal ions was studied. The cell superficial layer had a negative effect on Cu2+ adsorption of the bacterial cells. Cu2+ adsorption capacity of the separated cell envelopes was fivefold more than that of the intact cells, owing to the liberation of more and more binding sites during the separation process. Some main components in the cell envelope, such as the peptidoglycan (PEG) layer, outer membrane, and inner membrane, provide the capability for Cu2+ adsorption. The content of the components in the cell envelope is in the order inner membrane > outer membrane > PEG layer, and their Cu2+ adsorption capacity was in the order PEG layer > outer membrane > inner membrane. The total contribution of the separated PEG layer material to Cu2+ adsorption by the cell envelope was no more than 15%, and the outer membrane and inner membrane contributed about 30-35% and 25-30%, respectively. The relatively high phospholipid content in the outer membrane may be the major reason for the higher adsorption capacity of the outer membrane to Cu2+ and, hence, such a high Cu2+ adsorption capacity of P. putida 5-x cell envelope.

Adsorption↗
PubMed2006

Transfection of nm23-H1 increased expression of beta-Catenin, E-Cadherin and TIMP-1 and decreased the expression of MMP-2, CD44v6 and VEGF and inhibited the metastatic potential of human non-small cell lung cancer cell line L9981.

Nm23 is a metastasis suppressor gene. In this report, we transfected nm23-H1 cDNA into L9981, a human large cell lung cancer cell line with nm23 negative expression, and made a stable transfectant. L9981-nm23-H1 cells exhibited lower cells proliferation rate, more G0/G1 phase growth and an increase in apoptosis with a dramatic decreased in the tumor cells ability to metastasize. L9981-nm23-H1 cells also demonstrated a significantly reduced lymph node and pulmonary metastatic capacity in vivo when injected into the nude mice. Furthermore, we used DNA microarray analysis to explore the change in expression of the metastasis-related genes in L9981-nm23-H1 cells. We found that the expression of beta-Catenin, E-Cadherin and TIMP-1 were significantly increased while expression MMP-2, CD44v6, and VEGF was dramatically decreased in L9981-nm23-H1, as confirmed by RT-PCR and western blot. These results demonstrated that nm23-H1 can suppress the mobility and metastatic capacity of cancer cells and the molecular mechanism by which nm23-H1 suppresses tumor metastasis may be via increasing the expression of metastasis-related genes such as beta-Catenin, E-Cadherin and TIMP-1 and decreasing the expression of MMP-2, CD44V6 and VEGF.

Adenocarcinoma↗
PubMed2005

Laxatives for the treatment of hemorrhoids.

BACKGROUND: Symptomatic hemorrhoids are a common medical condition, which increase in prevalence in women during pregnancy and postpartum. Although the evidence appears to be inconclusive, narrative reviews and clinical practice guidelines recommend the use of laxatives (and fiber) for the treatment of hemorrhoids and relief of symptoms. This is due to their safety and low cost. OBJECTIVES: To evaluate the impact of laxatives on a wide range of symptoms in people with symptomatic hemorrhoids. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2005), MEDLINE (1966 to 2005), EMBASE (1980 to 2005), CINAHL (1982 to 2005), BIOSIS, and AMED (Allied and Alternative Medicine Database), for eligible trials (including conference proceedings). We sought missing and additional information from authors, industry, and experts in the field. SELECTION CRITERIA: We selected all published and unpublished randomised controlled trials that compared any type of laxative to placebo or no therapy in any patient population. DATA COLLECTION AND ANALYSIS: Two authors independently screened studies for inclusion and retrieved all potentially relevant studies. Data were extracted from studies that met our selection criteria on study population, intervention used, pre-specified outcomes, and methodology. We extracted methodological information for the assessment of internal validity: existence and method of generation of the randomization schedule, and method of allocation concealment; blinding of caregivers and outcomes assessors; numbers of and reasons for participants lost to follow up; and use of validated outcome measures. MAIN RESULTS: Seven randomised trials enrolling a total of 378 participants to fiber or a non-fiber control were identified. Meta-analyses using random-effects models showed that laxatives in the form of fiber had a beneficial effect in the treatment of symptomatic hemorrhoids. The risk of not improving hemorrhoids and having persisting symptoms decreased by 53% in the fiber group (risk reduction (RR) 0.47, 95% CI 0.32 to 0.68). These results are compatible with large treatment effects regarding prolapse, pain, itching, although the pooled analyses showed a tendency toward no-effect for these parametres. The effect on bleeding showed a significant difference in favour of the fiber (RR 0.50, 95% CI 0.28 to 0.89). Studies including data on multiple follow ups (usually after six weeks and three months) showed consistent results over time. However, we have to stress two possible limitations of this review: the risk of publication bias, and only moderate study quality. AUTHORS' CONCLUSIONS: The use of fiber shows a consistent beneficial effect for relieving overall symptoms and bleeding in the treatment of symptomatic hemorrhoids.

Cathartics↗
PubMed2005

Retinal nerve fiber layer measurements do not change after LASIK for high myopia as measured by scanning laser polarimetry with custom compensation.

PURPOSE: Scanning laser polarimetry (SLP) estimates retinal nerve fiber layer (RNFL) thickness through measurement of retardation of polarized light passing through the birefringent RNFL and cornea. A compensation method is incorporated to eliminate the anterior segment contribution to the total birefringence measured. LASIK is a technique that corrects myopia by ablating corneal tissue. This study evaluated RNFL measurements before and after LASIK as determined by SLP with a new custom compensation device set for the individual cornea before and after ablation. DESIGN: Interventional case series. PATIENTS AND METHODS: Patients underwent SLP measurements before and 30 days after LASIK for high myopia with customized compensation for anterior segment birefringence. Postoperative measurements were obtained with both the same compensation as was used preoperatively and with newly determined customized compensation. Standard RNFL parameters obtained before and after ablation with customized compensation were compared by use of paired Student's t tests with Bonferroni's correction for multiple comparisons. Postoperative measurements were also compared with those obtained preoperatively with the same corneal compensation measures as used preoperatively. MAIN OUTCOME MEASURES: Retinal nerve fiber layer parameters as determined by SLP before and after LASIK with 2 custom cornea compensator settings postoperatively. RESULTS: Fifty-seven eyes of 29 patients with myopia > -5.00 diopters underwent LASIK (average central ablation depth 101+/-11.3 mum). None of the 13 parameters showed statistically significant differences between preoperative and postoperative values with individually determined corneal compensation. When the preoperative corneal compensation was used postoperatively, 10 of 13 parameters were significantly changed. Comparison of the compensator settings before and after LASIK showed substantial differences in some individuals. On the average, there was a statistically significant change in the slow polarization axis of the cornea, with no statistically significant change in the magnitude of the birefringence, with some eyes showing increases and others decreases. The change in an individual cornea could not be predicted. CONCLUSIONS: Changes in RNFL measurements by SLP observed after LASIK in patients with high myopia are due to changes in corneal birefringence. These RNFL changes are not seen when customized compensation is applied for the cornea. Thus, LASIK does change the corneal birefringence but does not affect the RNFL.

Adult↗
PubMed2005

Optimizing cell preparation technique to enhance adsorption capacity of pseudomonas putida 5-x to heavy metal ions.

A heavy metal accumulation bacterium Pseudomonas putida 5-x isolated from electroplating effluent was used as biosorbent for heavy metal removal from wastewater. In order to compete with physical adsorbent, the optimization of the cell preparation technique for further improving its heavy metal adsorption capacity was conducted. Experimental results showed that the variation of medium compositions and cell growth age, and different cell pre-treating technique would result in the variation of the cell surface components and structural, hence the variation of adsorption capacity of the cell to heavy metal ions. With optimum cell culture conditions and pretreatment technique, the Cu2+ adsorption capacity of the cell was obviously increased from 51.2 mg g-1 to 89.6 mg g-1. The optimised P. putida 5-x cell could be reused at least five cycles to remove heavy metal ions from electroplating effluent with about 95% removal efficiency.

Adsorption↗
PubMed2005

Determination of the optimal and economical biofilter depth in an anaerobic hybrid reactor for treating livestock industrial wastewater.

A laboratory scale anaerobic hybrid reactor (AHR) being comprised of UASB and anaerobic biofilter was used to study the different biofilter depth with corresponding different critical HRT (1) and HRT (2) in treating livestock industrial wastewater, where the critical HRT (1) was defined as the HRT which resulted in the total COD in the effluent of the AHR exceeding in the influent at unsteady state, and the HRT (2) was defined as the HRT which resulted in the total COD in the effluent of the AHR exceeding the quality standard for discharging to sewer (in Hong Kong is Total COD < 1000 mg L1) at steady state. Two formulas expressing the relationship of different biofilter depth in the AHR and it's critical HRT (1) and HRT (2) in treating livestock industrial wastewater were obtained and used to design optimal and economical biofilter depth in a full scale AHR for treating livestock industrial wastewater on site. The performance of the full scale AHR indicated that using the experience formulas to design the optimal and economical biofilter depth in the full scale AHR for treating livestock industrial wastewater was successful. Experimental results also showed that the biofilter in the full scale AHR had not only physical filtration effect, but also had powerful biodegradation capability, furthermore, at unsteady state, the effect of biofilter on pollutant degrading in the full scale AHR was more great.

Anaerobiosis↗
PubMed2005

Evaluation of a novel integrated bioreactor--AOS system for treating oil-containing restaurant wastewater on site in Hong Kong.

AOS system is an anaerobic digestion reactor (A-section, UASB or UBF), oxidation degradation reactor (O-section, aerobic biofilm reactor), and physical sedimentation tank (S-section) 3-in-1 integrated reactor. The compact bioreactor was applied to treat oil-containing restaurant's wastewater on site in Hong Kong. The treatment efficiency was observed at different HRT. Experimental results indicated that the AOS system for treating oil-containing restaurant wastewater on site was feasible when HRT at 0.6 days above. During the running period, the net sludge generation rate of the AOS system was only about 0.08-0.09 g g(-1)removed COD, and the utmost COD specific volumetric removal rate (SVRR) of the system reached 2.77 gL(-1) d(-1). The utmost specific biomass substrate utilization rate (SBSUR) of COD in O-section and A-section reached 1.22 d(-1) and 0.128 d(-1), respectively. In addition, the experiment results showed that the AOS system with a filter in UASB (that is UBF's AOS system) could bear much more great HLR comparing with UASB's AOS and was more efficient for treating oil-containing restaurant's wastewater on site.

Biodegradation, Environmental↗