Biomedical subjects

Shu-Yu Lin

Publications and source records attributed to Shu-Yu Lin.

7 recordsLinked to original sources

PubMed2006

Speciation of selenium compounds by open tubular capillary electrochromatography-inductively coupled plasma mass spectrometry.

We introduce a T-type interface and a crossflow nebulizer to find ways to combine CEC with inductively coupled plasma MS (ICP-MS) detection for selenium speciation. For CEC separation, we employed a macrocyclic polyamine-bonded phase capillary as the separation column and a bare fused-silica capillary filled with the make-up liquid (0.05 M HNO3). The effect of nebulizer gas flow rate, make-up liquid flow, type, concentration and pH of the mobile phase on the separation have been studied. Tris buffer of 50 mM at pH 8.50 gave the best performance for selenium speciation. The reproducibility of the retention time indicated that sample injection by electrokinetic and nebulizer gas flow was better than that by self-aspiration alone. The detection limits for selenate, selenite, selenocystine and selenomethionine were found to be 2.40, 3.53, 12.86 and 11.25 ng/mL, respectively. Due to the high sensitivity and element-specific detection, as well as the high selectivity of the bonded phase, quantitative analysis of selenium speciation in urine was also achieved.

Buffers↗

PubMed2005

Synthesis and mesomorphic behavior of a donor-acceptor-type hexaazatriphenylene.

[structure: see text] A new donor-acceptor, 1,4,5,8,9,12-hexaazatriphenylene HATCNOR(n), is described. The synthesis of HATCNOR1 and HATCNOR6 is achieved by the regioselective displacement of 1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile (HATCN) with an alkoxy group. The X-ray analysis revealed self-assembly of HATCNOR1 in the solid state. HATCNOR6 is the new difunctionalized hexaazatriphenylene discotic liquid crystal.

Journal Article↗

PubMed2005

A modified protein precipitation procedure for efficient removal of albumin from serum.

Proteomic analysis of sera and the quest for identifying serum proteins as disease markers have often been hampered by the predominance of several highly abundant proteins including albumin and immunoglobulins. Prior albumin depletion so as to enrich for otherwise undetectable serum components is therefore a prerequisite in mining the serum proteome. In the course of evaluating several available methods and commercial kits, we have been able to refine the albumin depletion protocols and establish a modified albumin removal method using trichloroacetic acid (TCA)/acetone. Changes in major protein bands were monitored by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1-D SDS-PAGE) and used as the first screening strategy to evaluate and optimize for the precipitation experimental conditions. Our method showed better performance in efficiency, specificity, and costs in comparison with two commercially available albumin removal kits, and provides a simple pre-fractionation step for the proteomic analysis of serum biomarkers. Albumin isolated by the modified method is in the native state. Our method may offer a rapid method for purifying serum albumin in large scale.

Acetone↗

PubMed2003

Nitric oxide production by arsenite.

Arsenic can either enhance or reduce nitric oxide (NO) production, depending on the type of cell, the species and dose of arsenical tested. The mechanisms of how arsenic increases or decreases NO production remain unclear. Because NO is associated with many pathological conditions, it is conceivable that in those arsenic-target tissues, the NO production may be upregulated by continuous arsenic exposure, and a prolonged over-production of NO may cause inflammation hence a pathological condition. A prolonged interference with the normal physiological level of NO may also play a role in the initiation, promotion, and progression of arsenic-related human cancers. Suppression of NO production has been shown to reduce arsenite-induced oxidative DNA damage, inhibition of pyrimidine dimer excision, and micronuclei. However, a completely reliable story on how NO is involved in arsenic-related human disease is still lacking.

Animals↗

PubMed2003

An insight into the phenomena involved in a multiple-function stationary phase for the capillary electrochromatographic separation of 2'-, 3'-, and 5'-monophosphorylated nucleoside isomers.

The electrochromatographic separations of 2'-, 3'- and 5'-monophosphates of adenosine, guanosine, cytidine, and uridine were carried out with an open-tubular capillary column which was wall-coated with a highly selective reagent, 28-membered macrocyclic polyamine, 4, 8, 12, 18, 22, 26-hexaaza-1,15-dioxacyclooctaeicosane ([28]ane-N6O2). The effects of pH, composition and concentration of background electrolyte (BGE), applied voltage, column length, and the additive of the BGE, such as metal ions, borate, beta-cyclodextrin and organic solvent on the separation of these monophosphorylated nucleotide isomers were investigated. The results suggested that the interactions between analytes and the bonded groups on the wall predominantly comprise anion coordination and anion exchange in addition to the electrophoresis. A well-resolved electrochromatogram was obtained with the capillary column of 100 cm (75 cm effective length) x 75 microm inside diameter (ID), citrate buffer (20 mM, pH 3.99), applied voltage of -22 kV and detection at 254 nm. Column efficiency was found with the average theoretical plate numbers of 119,500/m and a low detection limit of 0.01 microM level could be achieved for the separation of these isomers.

Borates↗

PubMed2003

Reactive oxygen species are involved in arsenic trioxide inhibition of pyruvate dehydrogenase activity.

Arsenite was shown to inhibit pyruvate dehydrogenase (PDH) activity through binding to vicinal dithiols in pure enzyme and tissue extract. However, no data are available on how arsenite inhibits PDH activity in human cells. The IC(50) values for arsenic trioxide (As(2)O(3)) to inhibit the PDH activity in porcine heart pure enzyme preparation and in human leukemia cell line HL60 cells were estimated to be 182 and 2 microM, respectively. Thus, As(2)O(3) inactivation of PDH activity was about 90 times more potent in HL60 cells than in purified enzyme preparation. The IC(50) values for As(2)O(3) and phenylarsine oxide to reduce the vicinal thiol content in HL60 cells were estimated to be 81.7 and 1.9 microM, respectively. Thus, As(2)O(3) is a potent PDH inhibitor but a weak vicinal thiol reacting agent in HL60 cells. Antioxidants but not dithiol compounds suppressed As(2)O(3) inhibition of PDH activity in HL60 cells. Conversely, dithiol compounds but not antioxidants suppressed the inhibition of PDH activity by phenylarsine oxide. As(2)O(3) increased H(2)O(2) level in HL60 cells, but this was not observed for phenylarsine oxide. Mitochondrial respiration inhibitors suppressed the As(2)O(3)-induced H(2)O(2) production and As(2)O(3) inhibition of PDH activity. Moreover, metal chelators ameliorated whereas Fenton metals aggravated As(2)O(3) inhibition of PDH activity. Treatment with H(2)O(2) plus Fenton metals also decreased the PDH activity in HL60 cells. Therefore, it seems that As(2)O(3) elevates H(2)O(2) production in mitochondria and this may produce hydroxyl through the Fenton reaction and result in oxidative damage to the protein of PDH. The present results suggest that arsenite may cause protein oxidation to inactivate an enzyme and this can occur at a much lower concentration than arsenite binding directly to the critical thiols.

Animals↗

PubMed2002

Nucleoside monophosphates recognition using macrocyclic polyamine bonded phase in capillary electrochromatography.

An open-tubular wall-coated macrocyclic polyamine capillary column (70 cm x 75 microm ID) with 50 cm effective length for the separation of nucleoside monophosphates is described. Some parameters with respect to concentration, pH, composition of the buffer, and voltage in order to optimize the separation were studied. The coated capillary showed reversed electroosmotic flow (EOF), allowing anions to be separated in the co-EOF mode. Baseline separations were achieved for the eight nucleotides in less than 26 min using a background electrolyte consisting of H(3)PO(4)-NaH(2)PO(4) (30 mM, pH 3.10), an applied voltage of -15 kV, and detection at 254 nm. The macrocyclic polyamine on the capillary wall introduced anion coordination for the interaction with the analytes, the strength of which could be moderated by the type and concentration of the competing ion used in the background electrolyte (BGE). With a low concentration of the competing ion (phosphate ion), the migration behavior followed that obtained in the electrophoretic system. Increasing the concentration of the competing ion resulted in a faster migration and more complete elution of the analyte. The method established was also employed for the analysis of nucleotides in mushrooms. Aqueous extracts of mushrooms from different species and various extraction methods were injected directly for the analysis. Uridine 5'-monophosphate, guanosine 5'-monophosphate, adenosine 5'-monophosphate, and cytidine 5'-monophosphate, were found in the sample tested.

Agaricales↗