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Biomedical subjects

H C Yang

Publications and source records attributed to H C Yang.

At least 19 recordsLinked to original sources
PubMed2007

One-year results with extended-release tacrolimus/MMF, tacrolimus/MMF and cyclosporine/MMF in de novo kidney transplant recipients.

Once-daily tacrolimus extended-release formulation (Prograf XL, formerly referred to as MR or MR4) was compared with the twice-a-day tacrolimus formulation (TAC) and cyclosporine microemulsion (CsA), all administered in combination with mycophenolate mofetil (MMF), corticosteroids and basiliximab induction, in a phase 3, randomized (1:1:1), open-label trial in 638 de novo kidney transplant recipients. In combination with MMF and corticosteroids, XL had an efficacy profile comparable to TAC and CsA. XL/MMF and TAC/MMF were statistically noninferior at 1-year posttransplantation to CsA/MMF for the primary efficacy endpoint, efficacy failure (death, graft loss, biopsy-confirmed acute rejection (BCAR) or lost to follow-up). One-year patient and graft survival were 98.6% and 96.7% in the XL/MMF group, 95.7% and 92.9% in TAC/MMF group and 97.6% and 95.7% in CsA/MMF group. The safety profile of XL in comparison with CsA was similar to that observed with TAC in this study and consistent with previously published reports of TAC in comparison with CsA. The results support the safety and efficacy of tacrolimus in combination with MMF, corticosteroids and basiliximab induction, as well as XL as a safe and effective once-daily dosing alternative.

Adolescent↗
PubMed2006

Characteristics of natural organic matter degradation in water by UV/H2O2 treatment.

This study evaluated the UV/H2O2 system for degradation of natural organic matter in water. The photolysis experiments were conducted in a 10-l batch reactor using a 450-watt high-pressure mercury vapor lamp as the light source. The addition of H2O2 in water greatly improved the rate of humic acid degradation by UV light and 90% of the humic acid was removed within 30 min of photolysis. Kinetic data showed that the first-order reaction could be used to describe the kinetics of both humic acid oxidation and H2O2 decomposition, and the optimum H2O2 dose was 0.01%-0.05% for humic acid oxidation. It was also observed that the absorption of UVC (UV with wavelength between 200 and 280 nm) is responsible for the dissociation of H2O2 to generate the reactive hydroxyl radicals. Depending on the initial dosages, the H2O2 added to the system can be completely decomposed by UV within 50 to 90 minutes. Upon UV irradiation, the humic intermediates with smaller molecular sizes increase as a result of the degradation of larger humic substances. Photolysis of surface water also shows that the UV/H2O2 was effective in reducing trihalomethanes (THMs) formation in treating surface water with high contents of organic precursors. The distribution of THMs shifted from chlorine-THMs to bromine-THMs after UV/H2O2 treatments when bromide was present in water. However, higher H2O2 dosages would be necessary for the photolysis of surface water containing high concentrations of organic THM precursors. As observed from the Fourier transform infrared (FTIR) spectra, the functional groups of treated humic acids were destructed significantly, including -OH (from -COOH and -COH), aromatic -C=C, and -C=O conjugated with aromatic rings.

Hydrogen Peroxide↗
PubMed2005

Designing optical-fiber modulators by using magnetic fluids.

To reduce interface loss between optical fibers and devices in telecommunication systems, the development of an optical-fiber-based device that can be fused directly with fibers is important. A novel optical modulator consisting of a bare fiber core surrounded by magnetic fluids instead of by a SiO2 cladding layer is proposed. Applying a magnetic field raises the refractive index of the magnetic fluid. Thus we can control the occurrence of total reflection at the interface between the fiber core and the magnetic fluid when light propagates along the fiber. As a result, the intensity of the outgoing light is modulated by variation in field strength. Details of the design, fabrication, and working properties of such a modulator are presented.

Journal Article↗
PubMed2004

Magnetocardiography of animals in magnetically shielded environment with active compensation.

A high-Tc 1st-order electronic superconducting quantum interference device (SQUID) gradiometer system is constructed to study the magnetocardiogram (MCG) of rabbits in a moderately magnetically shielded environment with active compensation. In the noisy hospital environment, the noise cannot be completely reduced with the 1st-order gradiometer, therefore, a reference SQUID with active compensation was used to further reduce the noise level leaking into the room. The MCG system was equipped with a x-y translation bed. We used a low-pass filter with the cut off frequency at 44 Hz, a high-pass filter with the cut off frequency at 0.1 Hz and the 60 Hz notch filter to reduce the power line interference. The noise level of the 1st order gradiometer MCG system in this moderately magnetically shielded room was about 1 pT/square root of Hz1/2 at 1 Hz. The MCG of a normal rabbits was measured with this system and a MCG contour map and a current density distribution was constructed.

Animals↗
PubMed2004

High-Tc SQUID magnetocardiography imaging system.

We set up a high-Tc SQUID system for magnetocardiography (MCG) in a moderately magnetically shielded room. The electronically balanced gradiometer consists of superconducting quantum interference device (SQUID) magnetometer. One reference SQUID was mounted above the sensing SQUID while the sensing SQUID is seated at the bottom of the cryostat. The baseline of the gradiometer is varied from 5 cm to 7 cm. The output of the MCG signal was filtered with the band pass filter (0.5 - 40 Hz) and the power-line filter. The MCG system was used to detect the magnetic signal of the human heart. Equivalent current sources were used to study the inverse problem.

Body Surface Potential Mapping↗
PubMed2004

Genomic characterization of two Chinese isolates of porcine respiratory and reproductive syndrome virus.

The genomes of two isolates of porcine respiratory and reproductive syndrome virus (PRRSV) from China, designated HB-1(sh)/2002 and HB-2(sh)/2002, were sequenced and analyzed. The size of the genomes of HB-1(sh)/2002 and HB-2(sh)/2002 were 15,411 and 15,373 nucleotides respectively, excluding the poly(A) tails. Comparative analysis with the genomic sequences of another Chinese isolate (BJ-4) and North American (VR2332) and European (Lelystad virus, LV) viruses revealed that HB-1(sh)/2002 shared 89.8% identity with BJ-4 and VR2332, but only 54.7% with LV; while HB-2(sh)/2002 shared 89.4% and 89.5% identity with BJ-4 and VR2332 respectively and 54.3% with LV, indicating that the two new Chinese isolates were related to the North American PRRSV genotype. Phylogenetic analysis based on the nucleotide sequence of the structural protein ORF's showed that the two new Chinese isolates belong to same genetic subgroup. HB-2(sh)/2002 additionally exhibited variations in the NSP2 nonstructural protein encoded by ORF1 and the structural protein GP3 encoded by ORF3 in comparison with other North American PRRSV isolates, namely a 12 amino acids deletion in Nsp2 and one amino acid deletion in GP3 were found in HB-2(sh)/2002. Therefore, HB-2(sh)/2002 was a novel strain with unique deletions.

5' Untranslated Regions↗
PubMed2001

Arp2/3 complex and actin dynamics are required for actin-based mitochondrial motility in yeast.

The Arp2/3 complex is implicated in actin polymerization-driven movement of Listeria monocytogenes. Here, we find that Arp2p and Arc15p, two subunits of this complex, show tight, actin-independent association with isolated yeast mitochondria. Arp2p colocalizes with mitochondria. Consistent with this result, we detect Arp2p-dependent formation of actin clouds around mitochondria in intact yeast. Cells bearing mutations in ARP2 or ARC15 genes show decreased velocities of mitochondrial movement, loss of all directed movement and defects in mitochondrial morphology. Finally, we observe a decrease in the velocity and extent of mitochondrial movement in yeast in which actin dynamics are reduced but actin cytoskeletal structure is intact. These results support the idea that the movement of mitochondria in yeast is actin polymerization driven and that this movement requires Arp2/3 complex.

Actin-Related Protein 2↗
PubMed2001

Mitochondrial inheritance in budding yeast.

During the past decade significant advances were made toward understanding the mechanism of mitochondrial inheritance in the yeast Saccharomyces cerevisiae. A combination of genetics, cell-free assays and microscopy has led to the discovery of a great number of components. These fall into three major categories: cytoskeletal elements, mitochondrial membrane components and regulatory proteins. These proteins mediate activities, including movement of mitochondria from mother cells to buds, segregation of mitochondria and mitochondrial DNA, and equal distribution of the organelle between mother cells and buds during yeast cell division.

Cell Cycle↗
PubMed2001

Extrusion of fluorescein diacetate by multidrug-resistant Candida albicans.

Over-expression of multidrug efflux transporters causes Candida albicans cells to be resistant to azole antifungal agents. There are several kinds of indicator for multidrug resistance (MDR) phenotype of higher eukaryotic cells. Calcein AM is a prefluorochrome that is known as a substrate for multidrug efflux transporters of mammalian cells. We investigated whether calcein AM was also extruded by the ATP-dependent multidrug transporter (cdr1p) of C. albicans. There was no significant difference in the accumulation of calcein AM between MDR cells and drug-susceptible cells of C. albicans even with sodium azide, suggesting that calcein AM may not be associated with the CDR1-gene-related multidrug efflux system of C. albicans. However, a structurally related prefluorochrome derivative, fluorescein diacetate (FDA), was shown to be extruded by the CDR1 mRNA-overexpressing yeast cells. In comparison with drug-susceptible cells, the resistant cells emitted very weak fluorescence when stained with FDA. Furthermore sodium azide increased the fluorescence of the resistant cells more than 20 times, whereas the fluorescence in the drug-susceptible cells with FDA and sodium azide was three to four times stronger. These results suggested that FDA might be extruded by the CDR1-related multidrug efflux transporter of C. albicans.

Antifungal Agents↗
PubMed2001

Mechanisms and kinetics of high-temperature cadmium sorption by packed bed of calcined kaolin.

Sorption experiments by passing CdCl2-carrying flue gas through the packed bed of calcined macro-porous kaolin particles were performed over a temperature range of 973-1173K and a CdCl2 partial pressure range of 8-16.1 Pa. The observed structural change of the sorbent mineral at the stage of sorption and the results of desorption tests revealed the characteristics of an irreversible chemical reaction as a major cadmium capturing mechanism. In the fully saturated kaolin sorbent, CdO x Al2O x 2SiO2 is present as a sorption reaction product together with a smaller amount of 2CdO x Al2O x 2SiO2. The increase in sorbent bed temperature resulted in an increase in the rate of sorption, but it had no effect on maximum cadmium uptake. The gas-phase CdCl2 diffusion into the macro pores of calcined kaolin had a negligible effect on the overall sorption rate. The reaction between gaseous CdCl2 and solid Al2O3 x 2SiO2 is very sensitive to the concentration of CdCl2 but relatively insensitive to the temperature of the sorbent bed. The order of reaction with respect to the CdCl2 vapor concentration was determined to be 3.26. The activation energy, Ea, was estimated as 5.56 kcal/mol according to the Arrhenius relationship.

Adsorption↗
PubMed2001

Purification and characterization of antithrombotics from Syzygium aromaticum (L.) MErr. & PERRY.

Two antithrombotic polysaccharides with relatively high molecular weight (HMW) and low molecular weight (LMW) were isolated from the flower buds of Syzygium aromaticum (L.) MERR. & PERRY (clove) by anion-exchange chromatography, hydrophobic interaction column chromatography and size exclusion chromatography (LMW: EC-2B-IIIa-2, M.W. ca. 34000; HMW: EC-2C-Ia-2, M.W. ca. 103000). The LMW polysaccharide was mainly composed of Rha, Gal, GalA and Ara (molar %: 24.1, 18.9, 18.0 and 17.9, respectively) with 10.8% of sulfate and 18.2% of protein. The HMW fraction consisted of Ara, Gal, Glc and Rha (molar %: 26.0, 23.7, 17.5 and 12.4, respectively) with 15.4% of sulfate and 8.0% of protein. Both polysaccharides had the backbone of type I rhamnogalacturonan and the side chain of arabinan. Also, most of the sulfates were attached at the position 6 of 3-linked galactosyl residues. Compared to the antithrombotic activity of the HMW fraction (plasma clotting time of 145 s in APTT assay), the LMW fraction displayed a slightly low activity (90 s). However, animal studies indicated that crude LMW polysaccharide did not show acute toxicity, while the acute LD50 of the HMW fraction was approximately 2-fold lower than that of heparin.

Animals↗
PubMed2001

Purification and biological activity of acidic polysaccharide from leaves of Thymus vulgaris L.

Polysaccharides are involved in biological responses and can activate complement system, which plays an important role in primary host defense mechanisms. We investigated anticomplementary activities from spice plants and selected thyme (Thymus vulgaris L.) as a potent complementary activator. Acidic polysaccharide (TV-3-IIIA-IIa) purified from the hot-water extract of thyme leaves by DEAE-Toyopearl 650C, Butyl-Toyopearl 650M and Sepharose CL-6B column chromatography and preparative HPLC. The purified polysaccharide, TV-3-IIIA-IIa showed potent anticomplementary activity via classical and alternative pathway with the increase proportional to dosage. TV-3-IIIA-IIa seemed to be a homogenous polymer from the results of HPLC and its molecular mass was estimated as 180 kDa. TV-3-IIIA-IIa mainly consisted of galacturonic acid (44.8 mol%), glucuronic acid (16.7 mol%), arabinose (11.1 mol%), rhamnose (9.2 mol%), galactose (8.9 mol%) and small amounts of glucose, xylose, mannose and fucose. By methylation analysis and reactivity to beta-glucosyl Yariv reagent, TV-3-IIIA-IIa was assumed to contain small amounts of type II arabinogalactan and large amounts of pectin-like polysaccharides in the structure. Based upon these results, TV-3-IIIA-IIa was suggested to be a complement activator.

Animals↗
PubMed2001

Purification and characterization of anti-complementary polysaccharide from leaves of Thymus vulgaris L.

For the purification of the anti-complementary polysaccharide from Thymus vulgaris L., the hot-water extract of thyme leaves was successively fractionated by ethanol precipitation and ultra-filtration. The retentate with 300-kDa membrane cartridge showed a potent anti-complementary activity. It was further purified by open column chromatographies on DEAE-Toyopearl 650C, Butyl-Toyopearl 650M and Sephadex G-100, obtaining TV3-IIA-I, the purified anti-complementary polysaccharide. The anti-complementary polysaccharide exhibited the anti-complementary activity via both classical and alternative pathways. Based upon the methylation analysis and the reaction with beta-glucosyl Yariv reagent, the anti-complementary polysaccharide from thyme might contain an arabinogalactan moiety, at least in part.

Chromatography, Ion Exchange↗
PubMed2001

Effects of polysaccharides from rhizomes of Curcuma zedoaria on macrophage functions.

The effects of Curcuma zedoaria, which is used as a condiment, in perfumery, and as a medicine, on immune response were investigated by measuring macrophage-stimulating activity in macrophages and RAW 264.7 cells. In this study, CZ-1 and CZ-1-III, the fractions partially purified from C. zedoaria, had a strong, dose-dependent lysosomal enzyme activity. It was suggested that active portions of CZ-1-III were polysaccharides rather than proteins. Phagocytic activity increased as a similar pattern in both the gram-negative and gram-positive bacteria, time-dependently. It was demonstrated that CZ-1-III can augment the oxygen burst response but had an even higher activity in vivo than in vitro. Also a significant increase of H2O2, NO, and TNF-alpha production was observed. However, the production of TNF-alpha at the concentration of 1,000 microg/ml decreased. These data suggested that C. zedoaria had macrophage-stimulating activity and the possibility of being used as a biological response modifier.

Animals↗
PubMed2001

[Illness knowledge, social support and self care behavior in adolescents with beta-thalassemia major].

The purpose of this study was to explore the relationships among illness knowledge, social support and self-care behavior in adolescents with beta-thalassemia major. The subjects were 58 beta-thalassemia major adolescents recruited from the pediatric hematology outpatient departments of three hospitals in North Taiwan. All data were analyzed by descriptive statistics, one-way ANOVA, t-test, Pearson correlation, and stepwise multiple regression. The results showed that: (1) Scoring in illness knowledge, the best was treatment knowledge, and the worst was the knowledge of complications and symptoms. (2) The result for social support indicated that the family was the major source of support, and that classmates/friends provided the least support for thalassemic adolescents. (3) Scoring in self care behavior, the best was the medical and chelate therapy, and the worst was the management of problems and coping. (4) Individual characteristic differences, including sex, level of education, length of illness, complications of thalassemia, hospitalization due to thalassemic complications and receiving other treatments were correlated with their illness knowledge, social support or self-care behavior. (5) Illness knowledge, social support which were positively correlated with self-care behavior. (6) 50.0% of the variance in self-care behavior can be explained by emotional support from family, general knowledge of thalassemia, treatment knowledge and appraisal support from family. These findings could provide referential material for nursing research and nursing practice.

Adolescent↗
PubMed2000

Expression of angiotensin II type I receptor on erythroid progenitors of patients with post transplant erythrocytosis.

BACKGROUND: The pathogenesis of posttransplant erythrocytosis (PTE) has been elusive. Angiotensin converting enzyme inhibitors (ACEI) are efficacious in lowering the hematocrit of patients with PTE and angiotensin II (AII) type I receptors (AT1R) were recently detected on red blood cell precursors, burst-forming unit-erythroid- (BFU-E) derived cells. The purpose of this study was to determine whether there is increased expression of the AT1R on BFU-E-derived cells of patients with PTE, which might contribute to the pathogenesis of PTE. METHODS: Twelve healthy volunteers and 25 transplant recipients (13 patients with and 12 without PTE) were studied. BFU-E from peripheral blood were cultured in methylcellulose and BFU-E-derived colonies were harvested on day 10. Western blotting was used to detect AT1R and erythropoietin receptor (EpoR) expression. Intracellular free calcium in response to AII and erythropoietin (Epo) was measured with digital video imaging. RESULTS: There were no differences between transplant patients, with and without PTE, with respect to weight, age, sex, blood pressure, serum creatinine, circulating renin, angiotensin II, and Epo levels. Hematocrit, red blood cell number, BFU-E-derived colony number,and size were significantly increased in PTE compared with other two groups. AT1R expression was increased by 44% on the erythroid progenitors of PTE versus non posttransplant erythrocytosis patients and by 32% in PTE patients versus normal volunteers. AT1R expression correlated significantly with the hematocrit in PTE (Spearman r=0.68, P=0.01). In contrast, EpoR expression was equivalent in all groups. The AT1R was functional since a significant increase in [Ca(i)] was observed in Fura-2 loaded day 10 cells when stimulated with AII (182%, P<0.0001). CONCLUSION: An increase in AT1R density was observed in erythroid precursors of transplant patients with PTE compared to those without PTE and normal volunteers, and the level of AT1R expression in PTE correlated significantly with the hematocrit. In contrast, EpoR expression was not different in PTE compared with non posttransplant erythrocytosis or normal controls. This study supports a role for the AT1 receptor signaling pathway in the pathogenesis of PTE.

Angiotensin-Converting Enzyme Inhibitors↗