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Biomedical subjects

H J Liu

Publications and source records attributed to H J Liu.

At least 19 recordsLinked to original sources
PubMed2007

Selective removal of organochlorine pesticides (OCPs) from aqueous solution by triolein-embedded composite adsorbent.

A novel composite adsorbent (CA-T) was used for the selective removal of organochlorine pesticides (OCPs) from aqueous solution. The adsorbent was composed of the supporting activated carbon and the surrounding triolein-embedded cellulose acetate membrane. Scanning electron microscopy (SEM), N2 adsorption isotherms and fluorescence methods were used to characterize the physicochemical properties of CA-T. Triolein was perfectly embedded in the cellulose acetate membrane and deposited on the surface of activated carbon. The adsorbent was stable in water and no triolein leakage was detected during the test periods. Some organochlorine pesticides (OCPs), such as dieldrin, endrin, aldrin, and heptachlor epoxide, were used as model contaminants and removed by CA-T in laboratory batch experiments. The adsorption isotherm followed the Freundlich equation and the kinetic data fitted well to the pseudo-second-order reaction model. Results also indicated that CA-T appeared to be a promising adsorbent with good selectivity and satisfactory removal rate for lipophilic OCPs from aqueous solutions when present in trace amounts. The adsorption rate and removal efficiency for lipophilic OCPs were positively related to their octanol-water partition coefficients (log K(ow)). Lower residual concentrations of OCPs were achieved when compared to granular activated carbon (GAC).

Adsorption↗
PubMed2006

Expression of phosphorylated Stat3, cyclin D1 and Bcl-xL in extramammary Paget disease.

BACKGROUND: Stat3 (Signal transducer and activator of transcription-3) is an oncogene that plays a critical role in regulating fundamental processes associated with malignant transformation and cell survival. It participates in oncogenesis through upregulation of genes encoding apoptosis inhibitors (Bcl-xL) and cell cycle regulators (cyclin D1). The expression of Stat3, Bcl-xL and cyclin D1 protein has not been investigated in extramammary Paget disease (EMPD). OBJECTIVES: To study the expression of phosphorylated Stat3 (p-Stat3), Bcl-xL and cyclin D1 protein in EMPD and to evaluate the relationships among them. METHODS: Thirty-six tissue samples from 34 patients with primary EMPD were subjected to immunohistochemical staining for p-Stat3, cyclin D1 and Bcl-xL. RESULTS: Thirty-five of 36 specimens were clearly positive for p-Stat3 in EMPD, while 30 of 36 and 32 of 36 were positive for cyclin D1 and Bcl-xL expression, respectively. In all of four invasive EMPD specimens, strong and frequent expression of these three molecules was evident; moreover, two invasive EMPD specimens with lymph nodal metastasis showed very strong nuclear and membranous p-Stat3 staining. Two metastatic lymph node specimens showed very strong nuclear and local membrane p-Stat3 staining. There were significant correlations between p-Stat3 and cyclin D1 expression and between p-Stat3 and Bcl-xL expression. CONCLUSIONS: Our study shows that the expression of p-Stat3, cyclin D1 and Bcl-xL may play a pivotal role in the pathogenesis of EMPD.

Adult↗
PubMed2005

Cloning and nucleotide sequencing of the second internal transcribed spacer of ribosomal DNA for three species of Eimeria from chickens in Taiwan.

Coccidiosis of chickens caused by protozoan parasites of the genus Eimeria (Coccidia: Eimeriidae) is an enteric disease that results in great economic losses throughout the world, including Taiwan. Using polymerase chain reaction (PCR) with primers specific for the second internal transcribed spacer (ITS-2) of ribosomal DNA (rDNA), three species of Eimeria, E. tenella, E. maxima, and E. acervulina have been successfully characterised from chickens in Taiwan. The sizes of PCR products from various isolates representing these three species were between 370 and 580 base pairs (bp). After cloning and sequencing of the PCR products, high nucleotide sequence identity (96.8-100%) was observed within a species. In addition, ITS-2 nucleotide sequences for E. tenella had higher homology (98.5-99.3%) than E. maxima (81.6-96.5%) when compared with appropriate sequences deposited in GenBank. To our knowledge, this is the first report of a 412-bp ITS-2 sequence for E. acervulina from chickens.

Animals↗
PubMed2004

Lattice dynamics and electron-phonon interaction in (3,3) carbon nanotubes.

We present a detailed study of the lattice dynamics and electron-phonon coupling for a (3,3) carbon nanotube which belongs to the class of small diameter based nanotubes which have recently been claimed to be superconducting. We treat the electronic and phononic degrees of freedom completely by modern ab initio methods without involving approximations beyond the local density approximation. Using density functional perturbation theory we find a mean-field Peierls transition temperature of approximately 240 K which is an order of magnitude larger than the calculated superconducting transition temperature. Thus in (3,3) tubes the Peierls transition might compete with superconductivity. The Peierls instability is related to the special 2k(F) nesting feature of the Fermi surface. Because of the special topology of the (n,n) tubes we also find a phonon softening at the Gamma point.

Journal Article↗
PubMed2004

Household gas cooking: a risk factor for respiratory illnesses in preschool children.

AIMS: To explore the association of household gas cooking and respiratory illnesses in preschool children and their relation to outdoor air pollution. METHODS: Cross-sectional study among households that used gas stoves for cooking in two housing estates with contrasting air qualities in Hong Kong. A structured questionnaire was administered to parents of 426 children aged 0-6 years on their exposure to gas cooking and passive smoking, and the prevalence of respiratory illnesses. RESULTS: A total of 111 children (26.1%) were reported to have one or more respiratory illnesses (allergic rhinitis, asthma, bronchitis, sinusitis, and pneumonia). Of these, 21 (18.9%), 41 (36.9%), and 49 (44.1%) children were from households that cooked once, twice, and three times a day with gas. Hierarchical logistic regression models adjusting for socioeconomic, demographic, and indoor risk factors including passive smoking showed that household gas cooking was positively associated with respiratory illnesses. There was a dose-response relation between the frequency of gas cooking and the prevalence of respiratory illnesses in the estate with lower outdoor air pollution (OR = 6.1 and 3.2 respectively, for cooking three and two meals a day, compared to one meal a day). This relation was not observed in the more polluted estate. The association between the presence of a cigarette smoker in the household and the prevalence of respiratory illnesses was not significant. CONCLUSIONS: As gas cooking is common in urban households, the findings could have important public health implications.

Air Pollution, Indoor↗
PubMed2003

Enhancement of electrolarynx speech using adaptive noise cancelling based on independent component analysis.

The electrolarynx provides a valuable means of verbal communication for people who cannot use their natural voice-production mechanism, but technology has changed very little since it was introduced in the 1950s. The presence of background noise degrades the resulting speech. In this study background noise was reduced by a new method, independent component analysis-based adaptive noise cancelling, which can remove noise components of the primary input signal based on statistical independence, by incorporating both second-order and higher-order statistics. The method shows better performance than the conventional least mean square algorithm. Acoustic analysis of the denoised electrolarynx speech revealed a significant reduction in the amount of background noise. Results from the perceptual evaluations indicated that the new filtering technique produced a noticeable improvement in the acceptability of the electrolarynx speech in a quiet environment (from 1.75 to 2.49, arbitrary units) or a noisy environment (from 0.59 to 1.82). In general, there was no significant improvement or degradation in intelligibility in the quiet environment (from 52.7 to 53.3). However, the processing did improve the intelligibility in a babble-noise environment (from 24.9 to 40.6). The improvement in acceptability and intelligibility may increase the communication ability of the user in daily situations.

Acoustics↗
PubMed2002

Decolorization of reactive bright red K2G dye: electrochemical process catalyzed by manganese mineral.

This paper presents the results of the decolorization of azo dye K2G by the electrochemical process catalyzed by manganese mineral. It is proved that the MnOOH(s), main component of the manganese mineral, can catalyze the electrochemical process and enhance the decolorization efficiency. X-ray powder diffraction spectrum shows that the content of MnOOH(s) has not been changed at the end of the reaction. The effects of initial pH value, current density, concentration of electrolyte on the decolorization efficiency of the dye were investigated in detail. The initial pH effect on the decolorization efficiency of K2G dye is found not to be significant. The optimum current density is 0.26 A/dm2. In addition, a proposed catalyzing mechanism of manganese mineral is discussed in this paper.

Azo Compounds↗
PubMed2001

Homogeneous preparation of fluorescent-derivatized insulin and its application to competitive chromatographic immunoassays.

A homogeneously labeled insulin sample was prepared using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) as the fluorescent-labeling reagent, and this was successfully applied to a chromatographic immunoassay. This labeled insulin was prepared by tagging all the three amino groups with AQC. Both CE and chromatographic immunoassay experiments indicated that the prepared insulin still kept its immunoaffinity to its antibody. It was observed that appropriate concentrations of acetonitrile (ACN) were efficient in lowering the quenching of the fluorescent signal of tagged insulin, in keeping the dilute, tagged insulin in solution, and in improving its peak shape during a chromatographic immunoassay. The tagged insulin was found to be 20-400 times more sensitive than native insulin detected under ultraviolet detection conditions. A competitive chromatographic immunoassay system was set up and calibrated. The system was used for analyses of an insulin-spiked urine sample, with a 96% recovery obtained.

Acetonitriles↗
PubMed2001

Polarized absorption spectra of single-walled 4 A carbon nanotubes aligned in channels of an AlPO(4)-5 single crystal.

We report the polarized optical absorption spectra of single-walled 4 A carbon nanotubes arrayed in the channels of an AlPO (4)-5 single crystal. When the light electric field (E) is polarized parallel to the tube direction (c), the spectra display a sharp peak at 1.37 eV, with two broadbands at 2.1 and 3.1 eV. In the E perpendicular c configuration, the tube is nearly transparent in the measured energy region 0.5-4.1 eV. The optical dipole selection rules are discussed, and the absorption bands are assigned to the dipole transitions between the Van Hove singularities. The measured absorption spectra agreed well with the ab initio calculations of band structure based on the local density function approximation.

Journal Article↗
PubMed2001

Molecular characterization of Newcastle disease viruses isolated from recent outbreaks in Taiwan.

A reverse transcription-polymerase chain reaction (RT-PCR) was described which amplified a portion of the F and HN genes of Newcastle disease virus (NDV) isolated from recent outbreaks in Taiwan. The F protein plays an important role in determining the virulence of NDV strains. Sequencing of a region specifying the F protein cleavage site was therefore undertaken and this verified the correlation between deduced amino sequences and pathogenicity. Analysis of the deduced amino acid sequences of the F protein cleavage site showed that all recent Taiwanese isolates in 1999 were velogenic viruses. All the virulent viruses have the amino acid sequence 112RRQKR116 for the C-terminus of the F2 protein and phenylanine (F) at the N-terminus of the F1 protein, residue 117. A phylogenetic tree based on the nucleotide sequences of the F gene revealed that recent Taiwanese NDV isolates responsible for recent outbreaks were classified into two distant genotypes (VI and VII). Genotype VI virus is the first finding in Taiwan and has a highly genetic similarity to European isolates, suggesting that they might have originated from a common ancestor.

Amino Acid Sequence↗
PubMed2001

Sequence and phylogenetic analysis of the sigmaA-encoding gene of avian reovirus.

The full-length sigmaA-encoding gene nucleotide sequences (1251 bp) of ten avian reovirus (ARV) field-isolates and three vaccine strains were determined and analyzed to study the degree of genetic divergence and evolution. Strains were isolated over a 23-year period from different hosts, pathotypes, and geographic locations. A phylogenetic tree constructed from variation in the sigmaA nucleotide sequences among ARV isolates showed that Taiwanese isolates from different dates of isolation were grouped into two distant groups, indicating that they have evolved in nature. In paired identity analysis, there was over 97.3% nucleotide sequence identity in the sigmaA-encoding genes between group I Taiwanese isolates (T6, 750505, 919, and 918) and Japanese isolate OS161 as well as three US vaccine strains, suggesting that they might have descended from a common ancestor. However, the nucleotide sequences of these sigmaA-encoding genes varied extensively from those of group II Taiwanese isolates (601SI, R2/TW, 1017-1, 916, and 601G), displaying only 86% identity. These results revealed that the genetic diversity in the sigmaA-encoding gene of ARV correlated with the date of isolation and geographic locations.

Amino Acid Sequence↗
PubMed2001

Molecular characterisation of very virulent infectious bursal disease viruses in Taiwan.

The very virulent infectious bursal disease virus (vv IBDV) RNA in the bursa of Fabricius and spleen from experimentally infected chickens or field samples was detected by in situ hybridisation (ISH) with subsequent reverse transcription (RT)-polymerase chain reaction (PCR) and sequence analysis. The VP 2 gene of vv IBDV was detected by ISH in infected chicken tissues with a cloned digoxigenin (DIG)-labelled cDNA probe. To verify ISH, RT - PCR was used to amplify two 643- and 500-base pair fragments on the VP 2 gene of IBDV in the bursa of Fabricius. With all isolates, two c DNA fragments of 643 and 500 bp long, respectively, were generated as expected and further confirmed the specificity of ISH. Analysis of the hypervariable region (HVR) of the VP 2 gene revealed that a serine-rich heptapeptide SWSASGS located at amino acids 326-332 was conserved in recent Taiwanese strains, and two amino acid substitutions were found in the classical Taiwanese strains at positions 330M and 331W. Three amino acids were unique to the vv strains at positions 222A, 256I and 294I, compared with classical and variant strains. Sequence and phylogenetic analysis showed that the recent Taiwanese strains were closely related, very similar to vv IBDV s from Europe, China, Japan, and Africa, and distantly related to the Taiwanese classical strains.

Amino Acid Sequence↗
PubMed2001

The effectiveness of Tsu-San-Li (St-36) and Tai-Chung (Li-3) acupoints for treatment of acute liver damage in rats.

This study investigated the effects of acupuncture on carbon tetrachloride (CCl4) induced acute liver injury in male rats (n=36). The experimental groups were injected with CCl4 before, during, or after acupuncture therapy. Acupoints similar to the human Tsu-San-Li (St-36) and Tai-Chung (Li-3) were needled bilaterally. Rats treated with CCl4 had higher levels of serum glutamate-oxalate-transaminase (sGOT) and serum glutamate-pyruvate-transaminase (sGPT). Comparing the experimental groups, biochemical and pathological parameters of liver injury were significantly reduced when rats were acupunctured after, not before, CCl4-induced hepatotoxicity. Acupuncture at the Tsu-San-Li and Tai-Chung acupoints cannot prevent acute liver injury but may be effective in treating liver injury induced by carbon tetrachloride in rats.

Acupuncture Points↗
PubMed2001

Adsorption of chloroacetanilide herbicides on soil (I). Structural influence of chloroacetanilide herbicide for their adsorption on soils and its components.

Adsorption of chloroacetanilide herbicide acetochlor, alachlor, metolachlor and propachlor on soils and soil components was determined, and the structural differences of these herbicides were used to explain the order of sorptivity. Adsorption isotherms for all herbicide-soil combinations conformed to the Freundlich equation, and Ki increased with increasing soil organic carbon content. Kd on soil humic acid was greater than that on clay, but association of humic acid with clay reduced the overall adsorption. On all soils and soil humic acids, herbicide adsorption decreased in the order: metolachlor > acetochlor > propachlor > alachlor. On Ca(2+)-montmorrilonite, the order changed to metolachlor > acetochlor > alachlor > propachlor. FT-IR spectra of herbicide-clay or herbicide-humic acid-clay mixtures showed that H-bonding and charge transfer were the primary interaction pathways between these compounds and the surface of clay or humic acids. The different moieties attached to 2-chloro-acetanilide and their unique arrangement may have influenced the binding mechanisms and thus the sorptivity of these herbicides. This study indicates that the structural difference of pesticides in the same classes may be used as a molecular probe to obtain a better understanding of sorption mechanisms of pesticides on soil.

Acetamides↗
PubMed2001

Adsorption of acetanilide herbicides on soil and its components. II. Adsorption and catalytic hydrolysis of diethatyl-ethyl on saturated Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite.

Adsorption and catalytic hydrolysis of the herbicide diethatyl-ethyl [N-chloroacetyl-N-(2,6-diethylphenyl)glycine ethyl ester] on homoionic Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite clays were investigated in water solution. The Freundlich adsorption coefficient, Ki, got from isotherms on clay followed the order of Na+ approximately K+ > Mg2+ approximately Ca2+. Analysis of FT-IR spectra of diethatyl-ethyl adsorbed on clay suggests probable bonding at the carboxyl and amide carbonyl groups of the herbicide. The rate of herbicide hydrolysis in homoionic clay suspensions followed the same order as that for adsorption, indicating that adsorption may have preceded and thus caused hydrolysis. Preliminary product identification showed that hydrolysis occurred via nucleophilic substitution at the carboxyl carbon, causing the cleavage of the ester bond and formation of diethatyl and its dechlorinated derivative, and at the amide carbon, yielding an ethyl ester derivative and its acid. These pathways also suggest that hydrolysis of diethatyl-ethyl was catalyzed by adsorption on the clay surface.

Acetanilides↗
PubMed2001

Photodegradation of alpha-naphthaleneacetic acid in aqueous solution.

Kinetic processes of alpha-naphthaleneacetic acid (NAA) photolysis were studied under different conditions. The results showed that the ultraviolet light was more effective than fluorescent light in promoting degradation, and the degradation of NAA under ultraviolet light followed the first order kinetics with the photolysis rate constant of 1.15 x 10(-2) min-1 and half-life time (t1/2) of 60 min. Further, it was proved that the photolysis rate was higher in the presence of oxygen, titanium dioxide (TiO2), and low pH (acidic solution). At last, two photolysis intermediates were identified by GC-MS and possible photolysis pathways were proposed.

Kinetics↗
PubMed2001

[Experimental studies of the protective effects of basic fibroblast growth factor and Radix Salviae Miltiorrhizae on brain injury in rats caused by repeated exposures to +Gz].

Objective. To investigate the preventive and theralseutive (therapeutic) effects of basic fibroblast growth factor (bFGF) and Radix Salviae Miltiorrhizae (RSM) on brain injury caused by repeated +Gz exposures. Method. bFGF and RSM were injected intraperitoneally into SD rats before and after repeated +Gz exposures. The contents of excitatory amino acids (EAAs), nitric oxide (NO) and the number of cell apoptosis in the brain were measured, and were compared to those of the control group and normal saline (NS) group. Result. The contents of EAAs, NO and the number of cell apoptosis were significantly higher in repeated +Gz exposures group than those in control group. The values were markedly lower in bFGF and RSM group than those in repeated +Gz exposures group and NS group. Conclusion. bFGF and RSM showed distinct preventive and therapeutic effect on the brain injury induced by repeated +Gz exposures.

Animals↗