Biomedical subjects

Ching Yuan

Publications and source records attributed to Ching Yuan.

11 recordsLinked to original sources

PubMed2006

Identification of an amyloidogenic region on keratoepithelin via synthetic peptides.

Mutations of keratoepithelin (KE) gene in human chromosome 5q31 have been linked with corneal epithelial or stromal dystrophies characterized by the abnormal deposits of amyloid fibrils and/or non-amyloid aggregations in corneal tissue. We report herein that synthetic peptide containing amino acid (a.a.) residues of 515-532 of native KE protein can readily form beta-sheet-containing amyloid fibrils in vitro. Amyloid fibrils formed in various conditions from short synthetic peptides (containing a.a. 515-532 and 515-525, respectively) were characterized by thioflavin T (ThT) fluorescence assay, Congo red staining, electron microscopy (EM) and circular dichroism (CD). Triple-N-methylation of the synthetic peptides prevented the beta-sheet polymerization and related amyloid fibril formation. Comparison study with ThT fluorescence further demonstrated that synthetic peptides containing corneal dystrophy-related mutations within this region formed amyloid fibrils to various extents. Our results suggest that each individual dystrophy-related mutation by itself does not necessarily potentiate amyloid fibril formation of KE. Roles of these intrinsically amyloidogenic foci in abnormal KE aggregations and amyloid deposits of stromal corneal dystrophies await further investigation.

Amino Acid Sequence↗

PubMed2006

Electrokinetic enhancement removal of heavy metals from industrial wastewater sludge.

An enhanced electrokinetic process for removal of metals (Cr, Cu, Fe, Ni, Pb, Zn) from an industrial wastewater sludge was performed. The electrokinetic experiments were conducted under a constant potential gradient (1.25 V cm(-1)) with processing fluids of tap water (TW), sodium dodecylsulfate (SDS) and citric acid (CA) for 5 days. Results showed that metal removal efficiency of heavy metals for EK-TW, EK-SDS and EK-CA systems are 11.2-60.0%, 37.2-76.5%, and 43.4-78.0%, respectively. A highest metal removal performance was found in EK-CA system. The removal priority of investigated metals from sludge by EK process was found as: Cu > Pb > Ni > Fe > Zn > Cr. The results of sequential extraction analysis revealed that the binding forms of heavy metals with sludge after electrokinetic process were highly depend upon the processing fluid operated. It was found that the binding forms of metals with sludge were changed from the more difficult extraction type (residual and sulfate fractions) to easier extraction types (exchangeable, sorbed, and organic fraction) after treatment by electrokinetic process. Results imply that if a proper treatment technology is followed by this EK process to remove metals more effectively, this treated sludge will be more beneficial for sludge utilization afterwards. Before it was reused, the risk associated with metals of more mobile forms to the environment need to be further investigated. The cost analysis was also evaluated for the investigated electrokinetic systems.

Electrochemistry↗

PubMed2005

Effects of aerosol species on atmospheric visibility in Kaohsiung City, Taiwan.

Visibility data collected from Kaohsiung City, Taiwan, for the past two decades indicated that the air pollutants have significantly degraded visibility in recent years. During our study period, the seasonal mean visibilities in spring, summer, fall, and winter were only 5.4, 9.1, 8.2, and 3.4 km, respectively. To ascertain how urban aerosols influence the visibility, we conducted concurrent visibility monitoring and aerosol sampling in 1999 to identify the principal causes of visibility impairments in the region. In this study, ambient aerosols were sampled and analyzed for 11 constituents, including water-soluble ions and carbon materials, to investigate the chemical composition of Kaohsiung aerosols. Stepwise regression method was used to correlate the impact of aerosol species on visibility impairments. Both seasonal and diurnal variation patterns were found from the monitoring of visibility. Our results showed that light scattering was attributed primarily to aerosols with sizes that range from 0.26 to 0.90 pm, corresponding with the wavelength region of visible light, which accounted for approximately 72% of the light scattering coefficient. Sulfate was a dominant component that affected both the light scattering coefficient and the visibility in the region. On average, (NH4)2SO4, NH4NO3, total carbon, and fine particulate matter (PM2.5)-remainder contributed 53%, 17%, 16%, and 14% to total light scattering, respectively. An empirical regression model of visibility based on sulfate, elemental carbon, and humidity was developed, and the comparison indicated that visibility in an urban area could be properly simulated by the equation derived herein.

Aerosols↗

PubMed2004

Cytokeratin 12 in human ocular surface epithelia is the antigen reactive with a commercial anti-Galpha q antibody.

PURPOSE: In our initial attempt to identify differentiation markers for ocular surface epithelia, we observed a unique staining pattern by a commercial anti-Galphaq antibody. We further isolate and characterize the protein reactive with this anti-Galphaq antibody in human ocular surface epithelia. METHODS: Human donor corneoscleral buttons were sectioned and stained with a battery of commercial antibodies against Galpha proteins. Western blot analysis of cell lysates of corneal epithelial cells and HEK 293 cells transfected with Galphaq cDNA was used to determine the identity of the protein reactive with the anti-Galphaq antibody (E-17). Comparisons were made with another anti-Galphaq antibody (G4415) and an anti-cytokeratin 12C (J7) antibody. The isolated proteins reactive with E17 and J7 were then analyzed with two dimensional isoelectric focusing. Polypeptide sequences were identified using matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) after in-gel protein digestion. RESULTS: The E-17 anti-Galphaq antibody preferentially stained the entire corneal epithelia and the suprabasal layers of the limbus with complete absence of staining in the basal limbus and conjunctiva. Western blot analysis of corneal epithelial cells showed that E-17 antibody identified a protein with a molecular weight of 55 kDa. However, the antibody did not react with the purported antigen, Galphaq protein (42 kDa) produced by Galphaq cDNA. Another anti-Galphaq antibody (G4415) did not react with the 55 kDa protein but did react with the 42 kDa Galphaq protein. Further comparison of the E-17 antibody with the J7 antibody revealed that both recognized the 55 kDa band in one and two dimensional analysis. MALDI-TOF MS analysis confirmed that the 55 kDa protein of interest was actually cytokeratin 12 (CK12), rather than Galphaq protein. CONCLUSIONS: The commercial E-17 anti-Galphaq antibody did not react with Galphaq protein, its purported antigen. Instead, it recognized a 55 kDa protein, which was characterized to be cytokeratin 12 by isoelectric focusing and peptide fingerprinting with mass spectrometry. Based on its reactivity with CK12, this commercial E-17 can be used as a differentiation marker to study ocular surface epithelia.

Autoantigens↗

PubMed2004

How a G protein binds a membrane.

Heterotrimeric G proteins interact with receptors and effectors at the membrane-cytoplasm interface. Structures of soluble forms have not revealed how they interact with membranes. We have used electron crystallography to determine the structure in ice of a helical array of the photoreceptor G protein, transducin, bound to the surface of a tubular lipid bilayer. The protein binds to the membrane with a very small area of contact, restricted to two points, between the surface of the protein and the surface of the lipids. Fitting the x-ray structure into the membrane-bound structure reveals one membrane contact near the lipidated Ggamma C terminus and Galpha N terminus, and another near the Galpha C terminus. The narrowness of the tethers to the lipid bilayer provides flexibility for the protein to adopt multiple orientations on the membrane, and leaves most of the G protein surface area available for protein-protein interactions.

Animals↗

PubMed2004

Identification of the promoter region of the human betaIGH3 gene.

PURPOSE: To isolate and characterize the promoter of the human betaIGH3 gene. METHODS: Primer extension and CapSite Hunting methods were used to determine the transcription start sites (TSS) of the human betaIGH3 gene. Putative transcription factor-binding sites and potential promoter regions were identified by online tools. Two clones containing 3 Kb and 1 Kb of the 5'-flanking region of the betaIGH3 gene were isolated and their respective promoter activities were characterized. Various fusion constructs of betaIGH3 promoter-luciferase reporter were made to transfect A549 cells. The responses of these fragments to TGF-beta1 were also measured after being treated with TGF-beta1 at different concentrations. Several human and nonhuman cell lines were also transfected with the 1 Kb betaIGH3 promoter-reporter construct to compare the activity of the betaIGH3 promoter in these cells. RESULTS: The transcription start site of human betaIGH3 mRNA was determined to be 65 bp upstream of the ATG start codon. Both the 3 Kb (-3011 to -1) and 1 Kb (-1000 to -1) fragments displayed strong and comparable promoter activity in transfected cells. Truncation analyses in A549 cells identified the nucleotide region from -336 to -1 as having high promoter activity (minimal promoter). The results also indicated that the nucleotide fragment from -1000 to -646 contained negative regulatory elements. Twenty ng/ml TGF-beta1 upregulated the activity of the 1 Kb construct, but did not upregulate the activity of the -336 to -1 construct, suggesting that TGF-beta1 responsive elements existed in the region from -1000 to -336. The 1 Kb construct universally demonstrated promoter activity in all cell lines tested. CONCLUSIONS: We identified the betaIGH3 gene promoter with a distinct regulatory pattern in the 1 Kb region upstream of the ATG start codon. Further elucidation of the functions of this promoter region may facilitate understanding of betaIGH3 and its related corneal dystrophies.

Animals↗

PubMed2004

Impression cytology in the diagnosis of acanthamoeba keratitis with surface involvement.

PURPOSE: To evaluate the use of impression cytology in the diagnosis of Acanthamoeba keratitis with surface involvement. DESIGN: Observational case series. METHODS: Three patients with culture-proven superficial Acanthamoeba keratitis were studied. Patients' medical records were reviewed for clinical information, treatment procedures and disease course. Impression cytology specimens taken from the cornea of those patients were processed and observed by bright field microscopy. The main outcome measure was the cytopathological examination and identification of amoebic organisms. RESULTS: In each of these three patients, impression cytology specimens revealed the amoeba cysts. Some specimens also showed pleomorphic trophozoites with typical amoeba nuclei. CONCLUSION: Corneal impression cytology successfully detected the cysts and trophozoites of Acanthamoeba from patients with superficial amoeba keratitis. This indicates that impression cytology can be a useful technique to facilitate early diagnosis of Acanthamoeba keratitis with surface involvement.

Acanthamoeba↗

PubMed2004

Remediating ethylbenzene-contaminated clayey soil by a surfactant-aided electrokinetic (SAEK) process.

The objectives of this research are to investigate the remediation efficiency and electrokinetic behavior of ethylbenzene-contaminated clay by a surfactant-aided electrokinetic (SAEK) process under a potential gradient of 2 Vcm(-1). Experimental results indicated that the type of processing fluids played a key role in determining the removal performance of ethylbenzene from clay in the SAEK process. A mixed surfactant system consisted of 0.5% SDS and 2.0% PANNOX 110 showed the best performance of ethylbenzene removed in the SAEK system. The removal efficiency of ethylbenzene was determined to be 63-98% in SAEK system while only 40% was achieved in an electrokinetic system with tap water as processing fluid. It was found that ethylbenzene was accumulated in the vicinity of anode in an electrokinetic system with tap water as processing fluid. However, the concentration front of ethylbenzene was shifted toward cathode in the SAEK system. The electroosmotic permeability and power consumption were 0.17 x 10(-6)-3.01 x 10(-6) cm(2)V(-1)s(-1) and 52-123 kW h m(-3), respectively. The cost, including the expense of energy and surfactants, was estimated to be 5.15-12.65 USD m(-3) for SAEK systems, which was 2.0-4.9 times greater than that in the system of electrokinetic alone (2.6 USD m(-3)). Nevertheless, by taking the remediation efficiency of ethylbenzene and the energy expenditure into account for the overall process performance evaluation, the system SAEK was still a cost-effective alternative treatment method.

Benzene Derivatives↗

PubMed2004

Optimized expression and refolding of human keratoepithelin in BL21 (DE3).

Keratoepithelin (KE) is an extracellular protein participating in cell adhesion and differentiation. Mutations of the KE gene (on 5q31 in humans) cause deposition of abnormal proteins (amyloid and non-amyloid) in corneal stroma and lead to several corneal dystrophies in humans. However, further studies on the KE protein have been limited by the intrinsic difficulty of purifying this protein. A high-expression plasmid containing human KE gene was constructed to generate recombinant KE proteins in Escherichia coli. The plasmid was transformed into E. coli BL21 (DE3) and the recombinant protein was expressed as an insoluble His-tagged fusion protein and purified by nickel chelation affinity chromatography under denaturing conditions. On average, 12 mg of purified KE was routinely obtained from 1L of culture media. The recombinant KE was refolded in arginine-containing dialysis solutions and the recovery of bioactive KE typically was approximately 70%. The procedures developed in this report should enable reproducible production of KE and related mutant proteins in large quantities and facilitate future studies on biochemical and biophysical properties of KE and the pathogenesis of related corneal dystrophies.

Amino Acid Sequence↗

PubMed2003

Detection by impression cytologic analysis of conjunctival intraepithelial invasion from eyelid sebaceous cell carcinoma.

OBJECTIVE: To demonstrate that conjunctival impression cytologic analysis can detect conjunctival intraepithelial invasion from sebaceous cell carcinoma of the eyelid. DESIGN: Observational case series with cytopathologic correlation. PARTICIPANTS: Four patients with unilateral blepharoconjunctivitis and biopsy-proven sebaceous cell carcinoma. METHODS: Impression cytologic analysis specimens were taken from the suspicious area of the bulbar conjunctiva of each patient. Staining of the specimens was performed with a modified Papanicolaou stain. MAIN OUTCOME MEASURE: Observation of the abnormal tumor cells in the collected specimens by bright field microscope. RESULTS: The technique of impression cytologic analysis allowed collection and identification of abnormal tumor cells with characteristic cytoplasmic vacuoles. CONCLUSIONS: Conjunctival impression cytologic analysis successfully detected the ocular surface sebaceous carcinoma cells from the eyelid. However, full-thickness biopsies are necessary to confirm the diagnosis. Judicious use of impression cytologic analysis may facilitate the detection and diagnosis of this invasive tumor.

Adenocarcinoma, Sebaceous↗

PubMedDate not supplied

Tokay gecko photoreceptors achieve rod-like physiology with cone-like proteins.

The retinal photoreceptors of the nocturnal Tokay gecko (Gekko gekko) consist exclusively of rods by the criteria of morphology and key features of their light responses. Unlike cones, they display robust photoresponses and have relatively slow recovery times. Nonetheless, the major and minor visual pigments identified in gecko rods are of the cone type by sequence and spectroscopic behavior. In the ongoing search for the molecular bases for the physiological differences between cones and rods, we have characterized the molecular biology and biochemistry of the gecko rod phototransduction cascade. We have cloned cDNAs encoding all or part of major protein components of the phototransduction cascade by RT-PCR with degenerate oligonucleotides designed to amplify cone- or rod-like sequences. For all proteins examined we obtained only cone-like and never rod-like sequences. The proteins identified include transducin alpha (Galphat), phosphodiesterase (PDE6) catalytic and inhibitory subunits, cyclic nucleotide-gated channel (CNGalpha) and arrestin. We also cloned cDNA encoding gecko RGS9-1 (Regulator of G Protein Signaling 9, splice variant 1), which is expressed in both rods and cones of all species studied but is typically found at 10-fold higher concentrations in cones, and found that gecko rods contain slightly lower RGS9-1 levels than mammalian rods. Furthermore, we found that the levels of GTPase accelerating protein (GAP) activity and cyclic GMP (cGMP) phosphodiesterase activity were similar in gecko and mammalian rods. These results place substantial constraints on the critical changes needed to convert a cone into a rod in the course of evolution: The many features of phototransduction molecules conserved between those expressed in gecko rods and those expressed in cones cannot explain the physiological differences, whereas the higher levels of RGS9-1 and GAP activity in cones are likely among the essential requirements for the rapid photoresponses of cones.

Animals↗