Biomedical subjects

W Jin

Publications and source records attributed to W Jin.

At least 55 records · Page 3Linked to original sources

PubMed2000

Quantitative determination of glutathione in single human erythrocytes by capillary zone electrophoresis with electrochemical detection.

Glutathione (GSH) in single human erythrocytes is determined by capillary zone electrophoresis with end-column amperometric detection at a gold/mercury amalgam microelectrode. A capillary of 10 microm inner diameter is suitable for determination of GSH in an individual erythrocyte with a good signal-to-noise ratio. The limit of detection is 1 x 10(-7) mol/L or 26 amol and the linear dynamic range is 2 x 10(-7) to 2 X 10(-5) mol/L for the capillary. In this method, the calibration line is obtained with a capillary adsorbed before a certain amount of hemoglobin can be used for the quantification of GSH in the external standardization. The whole cell injection and the lack of necessity of a derivatization reaction lead to more accurate and precise results, which are closer to the macroscopic values of glutathione in human red blood cell (i.e., hemolysate) than those determined by indirect laser-induced fluorescence detection.

Adsorption↗

PubMed2000

A new method of quantification of pipemidic-acid by capillary zone electrophoresis with end-column amperometric detection.

Capillary zone electrophoresis was employed for the determination of pipemidic acid using an end-column amperometric detection with a carbon fiber microdisk array electrode, at a constant potential of -1.10 V vs. saturated calomel electrode. The optimum conditions of separation and detection were 1.2 x 10(-4) mol/LNaOAc - 8.8 x 10(-4) mol/ LHOAc for the buffer solution, 20 kV for the separation voltage, 5 kV and 10 s for the injection voltage and the injection time. The limit of detection was 1.05 x 10(-7) mol/L or 189 amol (S/N=3). The relative standard deviation was 0.31% for the migration time and 2.0% for the electrophoretic peak current. The method was applied to determining pipemidic acid in human serum.

Anti-Infective Agents↗

PubMed2000

Quantitative assay of metronidazole by capillary zone electrophoresis with amperometric detection at a gold microelectrode.

Capillary zone electrophoresis was employed for the determination of metronidazole using end-column amperometric detection with a gold microelectrode at a constant potential of -0.52V vs. saturated calomel electrode. To overcome interference of oxygen in the solution, a deaeration injector and a deaeration protector at the detection cell were used. The optimum conditions of separation and detection are 1.0 x 10(-3) mol/L potassium dihydrogen citrate (KH2C6H5O7) for the buffer solution, 20 kV for the separation voltage, and 5 kV and 10 S for injection voltage and injection time, respectively. The limit of detection is 6.0 x 10(7) mol/L or 0.78 fmole (S/N = 3). The relative standard deviation is 3.9% for the electrophoretic peak current. The method was applied to the determination of metronidazole in human urine.

Electrophoresis, Capillary↗

PubMed2000

Determination of clozapine by capillary zone electrophoresis following end-column amperometric detection with simplified capillary/electrode alignment.

Capillary zone electrophoresis was employed for the determination of clozapine using an end-column amperometric detection at a carbon fiber array microdisk electrode with simplified capillary/electrode alignment. The optimum conditions of separation and detection are: Britton-Robinson buffer, pH 2.0 (1.3 x 10(-2) mol/L total concentration of acids, 3.2 x 10(-3) mol/L NaOH), 15 kV for separation voltage, 5 kV and 10 s for injection voltage and injection time, respectively. The limit of detection is 4.2 x 10(-7) mol/L or 1.2 fmole (signal to noise, S/N = 2). The relative standard deviation is 1.4% for the migration time and 2.5% for the electrophoretic peak current. The method was applied to the determination of clozapine in human blood. The recovery of the method is between 94-104%.

Clozapine↗

PubMed2000

A new capillary electrophoresis end-column amperometric detection system without the need for capillary/electrode alignment.

A self-aligning end-column amperometric detection system for capillary electrophoresis was constructed. In this system, the electrode and capillary were exchanged easily and the capillary/electrode alignment procedure is not required. Gold, gold/mercury amalgam, copper and carbon fiber could be used as the working electrode. The principle is in the use of two disk holders with the capillary and the electrode in the center, so that by inserting the disk holders into a groove in the working electrode port, the capillary and the electrode are automatically aligned and the distance between the capillary and the electrode is assured at 0.24 mm. The relative standard deviation obtained using five different gold/mercury amalgam microdisk electrodes for determination of cysteine was 1.5% for the migration time and 3.3% for the electrophoretic peak current. The simple and convenient system was attractive for the routine analysis by capillary electrophoresis with electrochemical detection. The system was applied to the determination of promethazine hydrochloride in human serum.

Electrodes↗

PubMed2000

Monitoring myoglobin by capillary zone electrophoresis with end-column amperometric detection.

Capillary zone electrophoresis was employed for the determination of myoglobin in human urine using end-column amperometric detection with a carbon fiber microelectrode at a constant potential of 1.80 V vs. saturated calomel electrode (SCF). The optimum conditions of separation and detection are: 3.73 x 10-4 mol/L sodium diethyl malonyl urea (barbitone sodium), 1.34 x 10-4 mol/L HCl for the buffer solution, 20 kV for separation voltage, 5 kV and 5 s for injection voltage and injection time, respectively. The limit of detection is 4.4 x 10-8 mol/L or 84 amole signal to noise (S/N = 2). The relative standard deviation is 2.9% for the migration time and 2.5% for the electrophoretic peak current. The method can be used for the determination of myoglobin in human urine. The samples can be directly injected and need no pretreatment. The method is also rapid, less than 2 min, and has a recovery rate of 94-106%.

Electrophoresis, Capillary↗

PubMed2000

Capillary electrophoresis/electrochemical detection system with on-line deoxygenation.

A capillary electrophoresis (CE)/electrochemical detection system with on-line deoxygenation was developed, consisting of a deoxygenation injector, a deoxygenation protector, and an electrochemical detection cell. When the system was utilized for 60 min, the steady-state current of oxygen detected could be dropped to 3% of the original value for the gold/mercury amalgam electrode and to 8% of the original value for the gold electrode, and the limit of detection could be decreased two orders of magnitude for the reducible analytes such as TI+ (from 3.1 x 10-5 mol/L to 8.0 x 10-7 mol/L) and metronidazole (from 3.8 x 10-5 mol/L to 4.0 x 10-7 mol/L).

Electrochemistry↗

PubMed2000

Suppression of streptococcal cell wall-induced arthritis by human chorionic gonadotropin.

OBJECTIVE: To determine whether human chorionic gonadotropin (HCG) contributes to pregnancy-associated immunosuppression, as observed clinically by an amelioration of symptoms in human autoimmune diseases, including rheumatoid arthritis, during pregnancy. METHODS: Administration of HCG was initiated 2 days prior to an arthritogenic dose of streptococcal cell wall (SCW) in nonpregnant female rats, and the development and severity of SCW-induced arthritis was monitored. Inflammatory mediators, including plasma nitrite/nitrate and cytokine levels, were measured. Inducible nitric oxide synthase (iNOS) protein and cytokine messenger RNA expression in joint tissue were compared between treated and untreated arthritic animals. RESULTS: Systemic administration of HCG resulted in a dose-dependent reduction in the clinical arthritis index. Consistent with the amelioration of clinical symptoms, HCG significantly reduced the inflammatory cell infiltration, pannus formation, and bone and cartilage degradation. Mechanistically, HCG therapy was associated with suppression of the overzealous production of tumor necrosis factor alpha, interleukin-6 (IL-6), and IL-1beta, which contribute to synovial pathology in animals with SCW-induced arthritis. Circulating nitric oxide and the amount of iNOS protein were also reduced. Furthermore, circulating transforming growth factor beta levels were elevated by the HCG, all of which suggest monocytes/macrophages as a potential target. CONCLUSION: These findings indicate that HCG exerts a protective effect in this experimental arthritis model, through modulation of inflammatory mediators.

Animals↗

PubMed2000

Structural Organization of the Atlantic Croaker Connexin 32.2 Gene and Its 5' Flanking Region.

Gonadotropic hormone stimulates the accumulation of connexin (Cx) 32.2 messenger RNA in ovaries of the marine teleost Atlantic croaker. This effect can be mimicked by protein kinase A (PKA) activators and blocked by PKA inhibitors as well as protein kinase C (PKC) stimulators. However, the mechanisms of Cx32.2 gene regulation are unknown. In this study, we determined the structure of the Cx32.2 gene as a first step toward characterizing the regulatory mechanisms of Cx32.2 gene expression. A cosmid library of croaker genomic DNA was screened with a Cx32.2 complementary DNA probe. One positive clone was subcloned and sequenced. The Cx32.2 gene contained two exons and one intron. The first exon contained a portion of the 5' untranslated region (UTR), and the second exon contained the remaining 5' UTR, the amino acid coding region, and the 3' UTR. The distal 5' flanking region also contained a sequence homologous to a different croaker Cx gene, Cx32.7, but it is unclear if this sequence constitutes a pseudogene or an exon of the Cx32.7 gene. The 5' flanking region of the Cx32.2 gene contained two core cyclic AMP response elements (CRE, CGTCA) and one full-consensus activating protein- (AP)-1 binding site (AGTCAG). The distal core CRE was associated with a sequence that enhances CRE activity (GAGC). A third core CRE site was present in the intron. These findings are consistent with the following hypotheses: the induction of ovarian Cx32.2 mRNA levels by gonadotropic hormone is at least partly mediated by CRE-dependent activation of the Cx32.2 gene, and the inhibition of basal and gonadotropic-hormone-stimulated ovarian Cx32.2 mRNA by PKC is due to negative effects on transcription via the AP-1 transcription factor complex. This study is the first to characterize the structure and putative response elements of the 5' flanking region of fish Cx genes.

Journal Article↗

PubMed2000

Thoracoscopic plication of diaphragmatic eventration using endostaplers.

Unilateral diaphragmatic eventration and paralysis require plication in cases of progressive dyspnea on exertion and recurrent respiratory infection. The patient, a 40-year-old woman, who had complained of worsening dyspnea on exertion and elevation of the left diaphragm on chest radiographs for 4 years, underwent plication by thoracoscopy with knifeless endostaplers. Improvements in pulmonary functions and dyspnea on exertion have been maintained for 14 months.

Adult↗

PubMed2000

Secretory leukocyte protease inhibitor mediates non-redundant functions necessary for normal wound healing.

Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor with anti-microbial properties found in mucosal fluids. It is expressed during cutaneous wound healing. Impaired healing states are characterized by excessive proteolysis and often bacterial infection, leading to the hypothesis that SLPI may have a role in this process. We have generated mice null for the gene encoding SLPI (Slpi), which show impaired cutaneous wound healing with increased inflammation and elastase activity. The altered inflammatory profile involves enhanced activation of local TGF-beta in Slpi-null mice. We propose that SLPI is a pivotal endogenous factor necessary for optimal wound healing.

Animals↗

PubMed2000

Discriminatory detection of extended-spectrum beta-lactamases by restriction fragment length dimorphism-polymerase chain reaction.

Plasmid-mediated resistance mechanisms to beta-lactams, comprising mostly extended-spectrum beta-lactamase (ESBL) production, lead to resistance against even the most recently developed beta-lactams in enterobacteria, which is now a serious threat to antibiotic therapy. In this work, the diagnostic ability of the restriction fragment length dimorphism (RFLD)-polymerase chain reaction (PCR) method in clinical samples was evaluated. Nine newly designed primer pairs were used to differentiate the genes encoding TEM-1a, SHV-12, MOX-1, MIR-1 and Toho-1 beta-lactamases. The RFLD-PCR was carried out successfully and these genes were differentiated by the sizes of their PCR product. This discriminatory detection of the genes was also confirmed by digestion with unique restriction enzyme sites and sequencing of the PCR products. The fragment sizes of PCR products digested with the enzymes were identical to the sizes calculated from nucleotide sequences of five beta-lactamase genes deposited in EMBL, GenBank and/or DDBJ databases and the sequences were also identical. In conclusion, the method and newly designed primers applied in this work can differentiate the ESBLs rapidly and effectively.

DNA Primers↗

PubMed2000

Quantitation of caffeine by capillary zone electrophoresis with end-column amperometric detection at a carbon microdisk array electrode.

Capillary zone electrophoresis is employed for the determination of caffeine using end-column amperometric detection with a carbon fiber microdisk array electrode at a constant potential of 1.45 V versus a saturated calomel electrode. The optimum conditions of separation and detection are 0.1 52mM NaH2PO4-0.648mM Na2HPO4 for the buffer solution, 20 kV for the separation voltage, 5 kV for the injection voltage, and 10s for the injection time. The limit of detection is 2.9 x 10(-4)mM or 1.2 fmol (signal-to-noise ratio = 2). The relative standard deviation is 0.68% for the migration time and 2.3% for the electrophoretic peak current. The method is applied to determining caffeine in human serum and a cola drink.

Beverages↗

PubMed2000

Capillary zone electrophoresis with electrochemical detection for the determination of glutathione in human red blood cells without preseparation of hemoglobin.

Interference is studied for the determination of glutathione (GSH) in human red blood cells by using capillary zone electrophoresis with end-column amperometric detection at a gold-mercury amalgam microelectrode. It is found that when interference substances such as hemoglobin (Hb) in the hemolysate flow off from the end of the separation capillary, they can be adsorbed on the surface of the electrode and interfere with the signal of GSH. If the concentration of hemolysate is lower than 0.5% (v/v), this phenomenon can be overcome because they are adsorbed on the surface of the capillary wall and do not flow off from the capillary. A method is developed for the determination of GSH in human erythrocytes without the preseparation of Hb.

Electrochemistry↗

PubMed2000

Inhibin is an important factor in the regulation of FSH secretion in the adult male hamster.

We investigated the importance of inhibin and testosterone in the regulation of gonadotropin secretion in adult male golden hamsters (Mesocricetus auratus). After castration, plasma concentrations of inhibin and testosterone were reduced to undetectable, whereas plasma follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were increased. After hemicastration, plasma FSH and LH increased moderately and plasma inhibin decreased to one-half its initial level. Plasma testosterone levels in hemicastrated animals decreased 3 h after hemicastration but returned to those in sham-operated animals at 6 h. Plasma LH in the castrated hamster declined comparably to intact animals with testosterone treatment; plasma FSH also decreased but still remained at levels higher than those in intact animals. After treatment with inhibin in long-term-castrated animals, plasma FSH decreased, whereas plasma LH was not altered. Intact males treated with flutamide, an anti-androgen, showed a significant increase in plasma LH but not in FSH. On the other hand, treatment with anti-inhibin serum induced a significant elevation in plasma FSH, but not in LH. Using immunohistochemistry, we showed that the inhibin alpha-subunit was localized to both Sertoli and Leydig cells. The present study in adult male hamsters indicates that FSH secretion is regulated mainly by inhibin, presumably from Sertoli and Leydig cells, and that LH secretion is controlled primarily by androgens produced from the Leydig cells. This situation is more similar to that of primates than of rats.

3-Hydroxysteroid Dehydrogenases↗

PubMed2000

Changes in plasma concentrations of inhibin A and inhibin B throughout sexual maturation in the male chimpanzee.

Profiles of circulating plasma inhibin A and inhibin B during sexual maturation in male chimpanzees were investigated by using two-site enzyme-linked immunoassay (ELISA). Plasma concentrations of testosterone and pituitary gonadotropins were also measured. Concentrations of inhibin B, testosterone, luteinizing hormone (LH) and prolactin increased with age throughout prepuberty to adulthood, whereas inhibin A level was low and there were no age-related changes in concentrations of either inhibin A and follicle-stimulating hormone (FSH). Inhibin B showed an inverse correlation with FSH in adult (7 years or order) but not in immature (6 years or younger) male chimpanzees. There was no correlation between plasma levels of FSH and testosterone throughout the period of sexual maturation. However, testosterone levels were positively correlated with inhibin B levels. These results suggest that circulating inhibin B is involved in the regulation of FSH secretion after puberty in adult male chimpanzees, and also that circulating inhibin B is an important form of inhibin as a marker of Sertoli cell function in adult male chimpanzees.

Aging↗

PubMed2000

Safety and immunogenicity of lyophilized, live attenuated hepatitis A vaccine in non-human primate model.

OBJECTIVE: To evaluate the safety and immunogenicity of lyophilized, live attenuated hepatitis A vaccine (H2 strain) in rhesus monkeys. METHODS: Nine adult rhesus monkeys were used as experimental animals. The rhesus monkeys without anti-HAV were divided randomly into the aqueous vaccination group (4 rhesus monkeys), the lyophilized vaccination group (3 rhesus monkeys), and the control group (2 rhesus monkeys). Monkeys were inoculated by intramuscular injection, with control monkeys being inoculated with Minimum Essential Medium Eagle (MEM). Following vaccination, the monkeys were observed for the development of diarrhoea and other adverse side-effects, such as changes in appetite, frequency of defaecation and stool consistency for seven days. At the weeks 2, 3, 4, 6, 8, 10 and 12 positnoculation, the peripheral blood was collected from all animals and assayed for anti-HAV and alanine aminotransferase (ALT) and aspartate aminotransferase (AST), at weeks 0, 4 and 8 postinocuation, needle-biopsy specimens were taken at weeks 0, 4, 8 and 12, all monkeys were sacrificed and tissue samples were taken from liver, lung, heart, kidney and brain for pathological examination at week 12. RESULTS: Animals were immunized with a dose of 7.0 logTCID50/ml which is stable after freeze-drying. During the 12-week observation, no animals showed abnormal elevations of liver enzymes (ALT and AST) and no change in appetite or activity. Two monkeys (one in the aqueous group and the other in lyophilized group) showed possible lesions at week 8. The lyophilized vaccine, in addition to eliciting an anti-HAV IgG response similar to aqueous vaccine (P > 0.05), also showed IgM anti-HAV response at week 2 which was not observed with aqueous vaccine. CONCLUSIONS: These results demonstrate that lyophilized, live hepatitis A vaccine is safe and highly immunogenic in primates, supporting its further evaluation in human clinical studies.

Animals↗

PubMed2000

Gene polymorphism in apolipoprotein E and presenilin-1 in patients with late-onset Alzheimer's disease.

OBJECTIVE: To evaluate the association of apolipoprotein E (apoE) and presenilin-1 (PS-1) gene polymorphism with late-onset Alzheimer's disease (AD). METHODS: A case-control study was undertaken to detect the polymorphism of apoE and PS-1 by polymerase chain reaction and digestion with the endonucleases of BspL I, Hha I and BamH I. RESULTS: The frequencies of apoE epsilon 3/4 genotype and epsilon 4 allele in late-onset AD (n = 42) were significantly higher than those of age-matched controls (P < 0.05). The frequencies of the apoE intron 1 enhancer (IE1) G/G genotype and G allele in late-onset AD were also significantly higher than those in controls (P < 0.05). The frequencies of the PS-1 1/1 genotype but not the 1 allele in AD were significantly higher than those in controls (P < 0.05). The apoE epsilon 4 allele was associated with a tripling of risk for late-onset AD compared with that with no epsilon 4 allele (odds ratio: 2.932). Homozygosity of the G allele in IE1 and 1/1 genotype in PS-1 was associated with a doubling of risk for late-onset AD, and odds ratios were 2.223 and 2.066, respectively. When the apoE epsilon 4 was controlled, the association between the IE1 G/G genotype AD was no longer statistically significant (P > 0.05). We sequenced the exon 4 of apoE in patients with late-onset AD, and found no other genetic polymorphism or mutation except for apoE epsilon 4 and IE1 G alleles associated with AD. CONCLUSION: apoE epsilon 4 gene appears to be the strongest gene risk factor for late-onset AD and its apparent association between the IE1 G/G genotype and late-onset AD is a consequence of the association between the epsilon 4 and IE1 G/G genotype. The PS-1/1 genotype is weakly associated with late-onset AD.

Aged↗