Wei Chen
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Wei Chen
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Schistosomiasis: an unusual finding of the cervix.
Journal: Obstetrics and gynecology
March/24/2012
Description

BACKGROUND

Schistosomiasis remains a major threat to women's health in many resource-poor countries and is being seen with increasing frequency in developed countries among immigrants and tourists who have a history of freshwater exposure in endemic areas.

METHODS

A 28-year-old asymptomatic African immigrant presented with an abnormal Pap test result showing rare atypical squamous cells. Colposcopy examination showed pale-yellow, finely granular cervical lesions. Calcified Schistosoma hematobium eggs were identified by histology but were absent in urine and stool specimens. Praziquantel treatment was initiated promptly, avoiding significant morbidity.

CONCLUSIONS

The differential diagnosis of female genital schistosomiasis should be considered for patients who have a history of residence in or travel to endemic areas, including asymptomatic patients and patients presenting a long time after exposure.

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A comparison of brain and behavioral effects of varenicline and nicotine in rats.
Journal: Behavioural brain research
October/17/2011
Description

We evaluated the effects of the smoking cessation aid varenicline and nicotine on brain activation, locomotor sensitization and cognitive functioning in rats. Blood oxygenation level dependent (BOLD) activation on fMRI was measured in awake adult male Sprague-Dawley rats in response to their first dose of varenicline 0.04 mg/kg administered intravenously and compared to saline controls. Other groups of rats were pretreated with daily injections of either varenicline 0.04 mg/kg or saline administered subcutaneously over 5 days, and then imaged on the sixth day while receiving an intravenous dose. The initial dose of varenicline produced patterns of brain activation similar to those previously seen with nicotine, increasing BOLD activation in the auditory, cingulate, insular, prefrontal, retrosplenial, temporal and visual cortices, as well as the hippocampus, nucleus accumbens, septum, and ventral tegmental area. However, the sixth dose produced significantly less BOLD activation than the initial dose in the hippocampus, insular cortex, prefrontal cortex, and temporal cortex, suggesting tolerance. Repeated doses of varenicline have thus the opposite effect of repeated nicotine dosing at 24h intervals, previously shown to produce sensitization of brain activation under the same experimental conditions. We also assessed the effects of varenicline on locomotor sensitization and performance in the Morris water maze. Compared to saline controls, varenicline treated rats showed no evidence of locomotor activation or sensitization, and showed improved performance times on the water maze only on the first day. This study points to different effects of varenicline and nicotine on neuronal and behavioral indices.

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Inactivation mechanism of chlorination in Escherichia coli internalized in Limnoithona sinensis and Daphnia magna.
Journal: Water research
November/1/2016
Description

Zooplankton may harbor microorganisms in the aquatic environment, thus protecting them from disinfection during drinking water treatment. However, few studies have evaluated the protective effect of internalization by zooplankton against bacterial disinfection. In this study, we investigated the role of zooplankton (Limnoithona sinensis and Daphnia magna) as a refuge for ingested bacteria against inactivation by chlorination. Only 30% of chlorine reached the internalized bacteria inside the digestive tract of zooplankton. However, this was sufficient to achieve 1.4 log inactivation of internalized Escherichia coli in L. sinensis and 1.2 log inactivation in D. magna at Ct values of 80 mg min/L. Inactivation of internalized bacteria was achieved through the active transfer of free chlorine in the bulk water into the zooplankton digestive tract during grazing activity. D. magna was more sensitive to hypochlorous acid than L. sinensis, and its grazing behavior was inhibited during the inactivation experiment.

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Adsorption of tetracycline to nano-NiO: the effect of co-existing Cu(ii) ions and environmental implications.
Journal: Environmental science. Processes & impacts
August/3/2014
Description

Nano-sized nickel oxide (nano-NiO) is a new nanomaterial that has shown great promise in many areas of application. Understanding its environmental fate and effects is critical for minimizing the potential environmental implications of this new material due to incidental and accidental releases in the future. In this study, we observed strong adsorption of tetracycline to nano-NiO and found that the adsorption affinity can be further enhanced by Cu(ii) ions - the observed distribution coefficient (Kd) values are 10(3.1) to 10(4.2) L kg(-1) in the absence of Cu(ii) and 10(3.0) to 10(5.5) L kg(-1) in the presence of Cu(ii); such adsorption affinities are even comparable to those of tetracycline to carbonaceous materials. The strong adsorptive affinities of nano-NiO for tetracycline are likely attributable to several mechanisms, including surface complexation, cation exchange, and electrostatic attraction. As a strong complexing agent, Cu(ii) can significantly enhance adsorption of tetracycline by serving as a bridging agent between tetracycline and nano-NiO. The findings of this study have important implications for the risk assessment of engineered nanomaterials - in aquatic environments nano-NiO (and likely other metal oxide nanomaterials) can strongly adsorb tetracycline antibiotics, resulting in the changes of environmental risks of the metal oxide nanomaterials and/or bioavailability of the adsorbed contaminants.

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Two-Dimensional Analysis of Cross-Junctional Molecular Interaction by Force Probes.
Journal: Methods in molecular biology (Clifton, N.J.)
March/2/2017
Description

Upon engagement with a specific ligand, a cell surface receptor transduces intracellular signals to activate various cellular functions. This chapter describes a set of biomechanical methods for analyzing the characteristics of cross-junctional receptor-ligand interactions at the surface of living cells. These methods combine the characterization of kinetics of receptor-ligand binding with real-time imaging of intracellular calcium fluxes, which allow researchers to assess how the signal initiated from single receptor-ligand engagement is transduced across the cell membrane. A major application of these methods is the analysis of antigen recognition by triggering of the T cell receptor (TCR). Three related methods are described in this chapter: (1) the micropipette adhesion assay, (2) the biomembrane force probe (BFP) assay, and (3) combining BFP with fluorescence microscopy (fBFP). In all cases, an ultrasoft human red blood cell (RBC) is used as an ultrasensitive mechanical force probe. The micropipette assay detects binding events visually. The BFP uses a high-speed camera and real-time image tracking techniques to measure mechanical variables on a single molecular bond with up to ~1 pN (10-12 Newton), ~3 nm (10-9 m), and ~0.5 ms (10-3 s) in force, spatial, and temporal resolution, respectively. As an upgrade to the BFP, the fBFP simultaneously images binding-triggered intracellular calcium signals on a single live cell. These technologies can be widely used to study other membrane receptor-ligand interactions and signaling under mechanical regulation.

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Alagebrium (ALT-711) improves the anti-hypertensive efficacy of nifedipine in diabetic-hypertensive rats.
Journal: Hypertension research : official journal of the Japanese Society of Hypertension
June/14/2015
Description

Combining drugs with complementary mechanisms of action may contribute to improved hypertension control in diabetic patients. Advanced glycation end-product (AGE) breakers, a new class of candidate drugs targeting aging-related cardiovascular dysfunction, may be useful as novel adjuvant agents to improve the efficacy of diabetic hypertension (DH) treatment. This study evaluated the effects of alagebrium (ALT-711), an AGE breaker, combined with nifedipine, a Ca(2+) channel blocker, in a rat model of streptozotocin-induced DH. Compared with monotherapy, combination treatment significantly decreased systolic and diastolic blood pressure values, increased the pulse pressure, and decreased the coefficient of variation of the systolic blood pressure. Plasma biochemistry indicated that the concentrations of prostacyclin and nitric oxide were increased. Gene expression analysis showed significantly decreased prepro-endothelin-1expression in the aorta. These results reveal that alagebrium significantly improves the anti-hypertensive actions of nifedipine in a rat model of DH and suggest its potential use in the successful control of clinical DH.

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Impact of Taiwan's integrated prospective payment program on prolonged mechanical ventilation: a 6-year nationwide study.
Journal: Respiratory care
February/25/2014
Description

OBJECTIVE

The integrated prospective payment program (IPP), which encourages the integrated care of mechanically ventilated patients in order to reduce the heavy utilization of high-cost ICUs, has been implemented by Taiwan's Bureau of National Health Insurance since July 2000. The aim of this study was to assess the impact of this program on weaning, hospital stay, mortality, and cost for patients requiring prolonged mechanical ventilation (PMV).

METHODS

A data set of 1,000,000 randomly selected insurance holders from the National Health Research Insurance Database, Taiwan, was retrospectively analyzed. We enrolled 7,967 adult patients (age ≥ 17 y) who required PMV (duration ≥ 21 d) over a 6 year period.

RESULTS

There were 3,275 patients on PMV before (1997-1999) and 4,692 patients on PMV after (2001-2003) the IPP implementation. After IPP implementation, PMV was found to be required in patients with a significantly higher age, lower urbanization level, higher income status, and a higher prevalence of neuromuscular disease (P < .001). In-hospital mortality was similar between the 2 periods (17.2% before vs 16.2% after, P = .26), but the weaning rate was significantly lower in the latter period (68.1% vs 64.2%, P < .001). Total hospital stay (75.3 d vs 95.1 d, P < .001) and duration of mechanical ventilation usage (55.8 d vs 71.6 d, P < .001) were both significantly higher after the IPP implementation. Total hospitalization cost in the PMV patients was significantly lower after IPP implementation.

CONCLUSIONS

Implementation of the IPP program reduced the total hospitalization cost, increased the duration of mechanical ventilation usage and stay, and reduced the weaning rate in PMV patients.

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Universal scaling of correlated diffusion in colloidal monolayers.
Journal: Physical review letters
January/5/2014
Description

Using the techniques of optical microscopy and particle tracking, we measure the correlated diffusion in a monolayer of uniform silica spheres dispersed at a water-air interface. It is found that the correlated motion of the interfacial particles can be well described by two universal response functions, the normalized longitudinal and transverse diffusion coefficients D(∥)(r/r0) and D(⊥)(r/r0), where r is the interparticle distance and r0=a(λS/a)(3/2) is a new scaling length, which depends on both the Saffman length λS and particle radius a. The obtained response functions characterize the crossover behavior of the colloidal monolayers from the subphase-dominated three-dimensional hydrodynamics at low surface coverage to the monolayer-dominated 2D hydrodynamics at high concentrations. The surface viscosity ηs(2) of the colloidal monolayer obtained by two-particle rheology compares well with the one-particle measurements.

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Floral reversion mechanism in longan (Dimocarpus longan Lour.) revealed by proteomic and anatomic analyses.
Journal: Journal of proteomics
June/21/2012
Description

Two-dimensional gel electrophoresis (2-DE) was used to analyze the proteins related to floral reversion in Dimocarpus longan Lour. Proteins were extracted from buds undergoing the normal process of flowering and from those undergoing floral reversion in three developing stages in D. longan. Differentially expressed proteins were identified from the gels after 2-DE analysis, which were confirmed using matrix-assisted laser desorption/ionization-time of flying-mass spectroscopy and protein database search. A total of 39 proteins, including 18 up-regulated and 21 down-regulated proteins, were classified into different categories, such as energy and substance metabolism, protein translation, secondary metabolism, phytohormone, cytoskeleton structure, regulation, and stress tolerance. Among these, the largest functional class was associated with primary metabolism. Down-regulated proteins were involved in photosynthesis, transcription, and translation, whereas up-regulated proteins were involved in respiration. Decreased flavonoid synthesis and up-regulated GA20ox might be involved in the floral reversion process. Up-regulated 14-3-3 proteins played a role in the regulation of floral reversion in D. longan by responding to abiotic stress. Observations via transmission electron microscopy revealed the ultrastructure changes in shedding buds undergoing floral reversion. Overall, the results provided insights into the molecular basis for the floral reversion mechanism in D. longan.

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Oxygen-Assisted Chemical Vapor Deposition Growth of Large Single-Crystal and High-Quality Monolayer MoS2.
Journal: Journal of the American Chemical Society
June/9/2016
Description

Monolayer molybdenum disulfide (MoS2) has attracted great interest due to its potential applications in electronics and optoelectronics. Ideally, single-crystal growth over a large area is necessary to preserve its intrinsic figure of merit but is very challenging to achieve. Here, we report an oxygen-assisted chemical vapor deposition method for growth of single-crystal monolayer MoS2. We found that the growth of MoS2 domains can be greatly improved by introducing a small amount of oxygen into the growth environment. Triangular monolayer MoS2 domains can be achieved with sizes up to ∼350 μm and a room-temperature mobility up to ∼90 cm(2)/(V·s) on SiO2. The role of oxygen is not only to effectively prevent the poisoning of precursors but also to eliminate defects during the growth. Our work provides an advanced method for high-quality single-crystal monolayer MoS2 growth.

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