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Y Su

Publications and source records attributed to Y Su.

At least 73 records · Page 4Linked to original sources
PubMed2000

Studies on the cytotoxic mechanisms of ginkgetin in a human ovarian adenocarcinoma cell line.

The cytotoxic effects of ginkgetin, a natural biflavone isolated from Selaginella moellendorffii Hieron, were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in three different human cell lines: ovarian adenocarcinoma (OVCAR-3), cervical carcinoma (HeLa) and foreskin fibroblast (FS-5). The concentrations of ginkgetin required to induce 50% death (EC50) in OVCAR-3, HeLa, and FS-5 were 3.0, 5.2, and 8.3 microg/ml, respectively. Morphological changes in cells and their nuclei, DNA fragmentation with a characteristic pattern of inter-nucleosomal ladder, and double-stranded DNA breaks were detected following treatment with 3 microg/ml of this biflavone for 24 h. Incubation with 5 microg/ml ginkgetin led to increased intracellular levels of hydrogen peroxide as early as 30 min. The cytotoxicity of ginkgetin was partially inhibited by pretreating cells with vitamin C, vitamin E or catalase. Catalase not only afforded the best protective effect among three antioxidants, but also reduced both the DNA fragmentation and double-stranded DNA breakage induced by ginkgetin. Moreover, the involvement of caspase(s) in ginkgetin-induced apoptosis was demonstrated by the activation of caspase 3 after drug treatment and the suppression of cell death by a broad-spectrum caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk). However, the protective effects of z-VAD-fmk and catalase were not additive. Taken together, our results indicated that the apoptosis induced by ginkgetin (especially at 5 microg/ml) is mediated mainly through the activation of caspase(s) by the hydrogen peroxide generated possibly through autooxidation of this biflavone.

Adenocarcinoma↗
PubMed2000

Determination of nicotinamide (NA) using its polarographic catalytic wave in the presence of KIO3.

Nicotinamide (NA) yields a polarographic catalytic wave with a peak potential -1.38 V (vs. SCE) in 0.1 mol/L HAc-NaAc (pH 4.7)/4 x 10(-3) mol/L KIO3 buffer solution. The sensitivity of the catalytic wave increased in one order of magnitude as compared to that of the responding reduction wave without KIO3. Based on this observation, a new method for the determination of NA was recommended. The second order derivative peak current was proportional to the NA concentration in the range of 5 x 10(-8)- 6 x 10(-7) mol/L. 0.11-fold vitamin B1, 0.13-fold B2, 0.14-fold B6 and 8-fold nicotinic acid amounts do not interfere the determination of 1 x 10(-6) mol/L NA. The proposed method was used to determine the NA content in multivitamin tablets, with good agreement to the declared amount.

Hydrogen-Ion Concentration↗
PubMed2000

Decreased meiotic reciprocal recombination in subtelomeric regions in Saccharomyces cerevisiae.

Reciprocal recombination (chiasma formation) between homologs appears to be essential for promoting chromosome segregation at the first meiotic division. However, chiasmata that form near the ends of chromosomes are much less efficient at promoting segregation. To determine the frequency of reciprocal recombination near the end of a chromosome, genetic markers were inserted at approximately 7 kb intervals within the leftmost 30 kb of chromosome I from Saccharomyces cerevisiae. Analysis of recombination between the markers indicated that meiotic reciprocal recombination rates were much lower than on the rest of the chromosome and that rates increased with distance from the telomere. Thus, S. cerevisiae has evolved a mechanism that minimizes the occurrence of chiasmata that cannot promote meiotic segregation. Low rates of recombination were independent of the SIR2 and SIR3 gene products, suggesting that any mechanism for suppressing recombination was different from transcriptional repression due to a telomere position effect.

Chromosomes, Fungal↗
PubMed2000

Androgen excess contributes to altered growth hormone/insulin-like growth factor-1 axis in nonobese women with polycystic ovary syndrome.

OBJECTIVE: To investigate the relationship between ovarian androgen excess and impaired growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis in nonobese women with polycystic ovary syndrome (PCOS). DESIGN: A prospective, controlled clinical study. SETTING: Reproductive Endocrine Unit, Department of Obstetrics and Gynecology, Jinling Hospital, Nanjing University School of Clinical Medicine. PATIENT(S): Six patients with PCOS with both clomiphene resistance and gonadotropin hyperreponsiveness and six controls with regular cycles, matched for age and body mass index (BMI). INTERVENTION(S): Bilateral ovarian wedge resection (OWR) was performed to induce ovulation surgically for these refractory women with PCOS. A GH stimulation test with oral L-dopa was arranged for controls and for patients with PCOS before and again 6 months later after OWR. MAIN OUTCOME MEASURE(S): Plasma GH, IGF-1, FSH, LH, testosterone, androstenedione, estradiol, progesterone, prolactin, insulin, and glucose. RESULT(S): Basal levels and areas under the response curve of GH and GH-IGF-1 ratio to L-dopa were significantly lower in patients with PCOS before surgery than those of controls. The OWR in patients with PCOS obviously reduced their androstenedione and testosterone levels and insulin-glucose ratios, and increased the GH and GH-IGF-1 responses to L-dopa. CONCLUSION(S): Impaired somatotrophic axis caused by a defect in central dopaminergic activity may be responsible for severe anovulation in these women with PCOS, which could be reversed by removing excessive androgens with OWR.

Adult↗
PubMed2000

Protocol for quantitative and qualitative analyses of the in vitro aggregation of synthetic beta-amyloid. A method applicable to the identification of substances that may have therapeutic efficacy for Alzheimer's disease.

Biochemical studies of beta-amyloid (Abeta) aggregation have been hampered by the lack of a simple method to examine simultaneously the extent of aggregation and the structural nature of the aggregates. Consequently, often only the extent of aggregation is analyzed and reported. This means that there is often no knowledge of whether the aggregates consist of fibrils, a structure crucial for their neurotoxicity. Here we describe the development of a protocol for quantitatively and qualitatively evaluating the in vitro aggregation of synthetic Abeta. Specifically, a fluorescein derivatized Abeta(1-42) peptide (FITC-Abeta(1-42)) was used as the aggregation material. We found that the fluorescent Abeta peptide aggregated as efficiently as the native ones and the extent of their aggregation could be determined accurately by fluorescence spectrophotometry. Significantly, our approach is also qualitative because it allows a direct structural examination of Abeta fibrils by fluorescence microscopy. In addition, this protocol can also be applied to the identification of substance(s) capable of inhibiting Abeta aggregation and further the assessment of the nature of such inhibition.

Alzheimer Disease↗
PubMed2000

Characterization of a 5'-flanking region supporting the transcription of mouse thymosin beta-4 in mouse NIH3T3 cells.

Expression of the gene coding for thymosin beta-4 (Tbeta-4), the major G-actin sequestering peptide in the cell, is regulated mainly at the level of transcription. In this study, we examined the nucleotide sequence of the 5'-flanking region (from -2202 to -881) of the mouse Tbeta-4 gene, and demonstrated that the DNA fragment from -278 to +410 of this gene was capable of directing the expression of a chloramphenicol acetyltransferase reporter gene in NIH3T3 cells. However, expression of the reporter gene in cells cannot be induced by interferon-alpha treatment even though a rapid activation of endogenous Tbeta-4 gene by this cytokine was observed. These results suggest that the projected interferon-stimulated response element (ISRE) might reside in other parts of the mouse Tbeta-4 gene.

3T3 Cells↗
PubMed2000

Carbon disulfide at a Chinese viscose factory external and internal exposure assessment.

This article presents the results of carbon disulfide exposure measurements in a Chinese viscose rayon factory. The objectives of the study were to identify the external exposure levels at a large factory and to investigate the 2-thiothiazolidine-4-carboxylic acid (TTCA) concentrations in the urine of the subjects who were exposed to carbon disulfide in the working place atmosphere. The metabolism of carbon disulfide in the exposed subjects was also studied in order to demonstrate the best points in time for the internal exposure sampling. The measurement of the amount of personal exposure to carbon disulfide in the air of the workplace was performed by GC-FPD; the presence of TTCA in the workers urine was analyzed by use of a modified HPLC method. The kinetics of TTCA excretion was studied by analyses at different time-points both during and after exposure to carbon disulfide in the subjects. A total of 155 personal samples were obtained. The carbon disulfide concentration in the staple viscose hall was 13.72 +/- 1.12 mg m-3 in terms of the geometric mean +/- geometric standard deviation, and was 20.05 +/- 1.33 mg m-3 in the filament spinning hall. The TTCA values in the subjects who worked in the staple spinning hall were 1.18 +/- 0.43 mg g-1 creatinine and 1.07 +/- 0.38 mg g-1 creatinine for subjects working in the filament spinning hall. The best time for TTCA sampling is at the end of the working shift, the TTCA excretion was stable for a period of 4-12 h after exposure of the subjects to the carbon disulfide. It might be that the Chinese have different anthropometric characteristics; a sampling bias may therefore appear among different races.

Adult↗
PubMed2000

Factors critical to the design and execution of epidemiologic studies and description of an innovative technology to follow the progression from normal to cancer tissue.

The results obtained from experimental studies of estrogen carcinogenesis need validation in epidemiologic studies. Such studies present additional challenges, however, because variations in human populations are much greater than those in experimental systems and in animal models. Because epidemiologic studies are often used to evaluate modest differences in risk factors, it is essential to minimize sources of errors and to maximize sensitivity, reproducibility, and specificity. In the first part of this chapter, critical factors in designing and executing epidemiologic studies, as well as the influence of sample collection, processing, and storage on data reliability, are discussed. One of the most important requirements is attaining sufficient statistical power to assess small genetic effects and to evaluate interactions between genetic and environmental factors. The second part of this chapter describes innovative technology, namely, Fourier transform-infrared (FT-IR) spectra of DNA that reveal major structural differences at various stages of the progression from normal to cancer tissue. The structural differences become evident from wavenumber-by-wavenumber statistical comparisons of the mean FT-IR spectra of DNA from normal to cancer tissues. This analysis has allowed distinguishing benign tissues from cancer and metastatic tissues in human breast, prostate, and ovarian cancers. This analysis, which requires less than 1 microg of DNA, is predicted to be used for detecting early cancer-related changes at the level of DNA, rather than at the cellular level.

DNA, Neoplasm↗
PubMed2000

Role of calpain in hypoxic inhibition of nitric oxide synthase activity in pulmonary endothelial cells.

Pulmonary artery endothelial cells (PAEC) were exposed to normoxia or hypoxia (0% O(2)-95% N(2)-5% CO(2)) in the presence and absence of calpain inhibitor I or calpeptin, after which endothelial nitric oxide synthase (eNOS) activity and protein content were assayed. Exposure to hypoxia decreased eNOS activity but not eNOS protein content. Both calpain inhibitor I and calpeptin prevented the hypoxic decrease of eNOS activity. Incubation of calpain with total membrane preparations of PAEC caused dose-dependent decreases in eNOS activity independent of changes in eNOS protein content. Exposure of PAEC to hypoxia also caused time-dependent decreases of heat shock protein 90 (HSP90) that were prevented by calpain inhibitor I and calpeptin. Moreover, the HSP90 content in anti-eNOS antibody-induced immunoprecipitates from hypoxic PAEC lysates was reduced, and repletion of HSP90 reversed the decrease of eNOS activity in these immunoprecipitates. Incubation of PAEC with a specific inhibitor of HSP90 (geldanamycin) mimicked the hypoxic decrease of eNOS activity. These results indicate that the hypoxia-induced reduction in eNOS activity in PAEC is due to a decrease in HSP90 caused by calpain activation.

Animals↗
PubMed2000

Inhibitory effects of intestinal mucus on bacterial adherence to cultured intestinal epithelial cells after surface burns.

OBJECTIVE: To investigate the relationship between intestinal mucus IgA content and mucus barrier function after surface burns. METHODS: Detection of IgA content in mucus was performed by enzyme linked immunosorbent assay (ELISA) at different time points after burns. Bacterial adherence to cultured epithelial cells (IEC-6) in vitro using E. coli was assessed for each group. RESULTS: The intestinal mucus barrier function declined, parallel to a decrease in IgA content after surface burn in mice. In the normal control group, mucus IgA content was 2.32 D lambda, and 2.51, 1.76, 1.49, 1.06 D lambda at 0.5 h, 1 h, 6 h and 24 h after burn, respectively. Bacterial adherence rate was 0.53 in control group, and 0.46, 0.69, 0.58, 0.81 at 0.5 h, 1 h, 6 h, 24 h after burn, respectively. CONCLUSION: The decrease of intestinal mucus IgA contents is one of the reasons why intestinal mucus barrier function declines after burns.

Animals↗
PubMed2000

[Color Doppler ultrasound and quantitative histologic study of angiogenesis in ovarian tumors].

OBJECTIVE: To investigate whether there is any correlation between minimum resistance index (RImin) and microvessel density (MVD) in ovarian tumors. METHODS: The intratumor artery RImin of 61 patients with ovarian tumor was measured by color doppler ultra-sound (CDU) preoperatively. MVD identified by von Willebrand factor was evaluated postoperatively. The relationship between RImin and MVD was analyzed. RESULTS: Compared with the RImin of benign ovarian tumors, the RImin in ovarian cancers was significantly lower (P < 0.001). MVD of ovarian cancer was significantly higher than that of benign tumor both at a 100 magnification (P < 0.01) and a 400 magnification (P < 0.03). There was a significant negative correlation between RImin and MVD at a 100 magnification in benign group (r = -0.67, P < 0.01), in malignant group (r = -0.91, P < 0.01), and in both of groups (r = -0.84, P < 0.01). CONCLUSION: Low RImin reflects high MVD in ovarian tumor.

Female↗
PubMed2000

[Relationship between CYP1A1, GSTM1 genetic polymorphisms and susceptibility to esophageal squamous cell carcinoma].

OBJECTIVE: To investigate the association between susceptibility of esophageal squamous cell carcinoma and the genetic polymorphisms of CYP1A1 and GSTM1. METHODS: Subjects were comprised of 107 esophageal cancer patients and 111 healthy controls. Genotyping of both CYP1A1 and GSTM1 were performed in cancer tissues of all 107 patients and peripheral blood leukocytes taken from the controls by polymerase chain reaction. RESULTS: There were no significant differences in the frequency distribution of CYP1A1 polymorphisms between esophageal cancer patients and healthy controls although the frequency of CYP1A1 with at least one allele of Val showed slightly higher in individuals with esophageal cancer. However, significant difference was observed in the frequency of GSTM1-nulled individuals with esophageal cancer comparing with the controls (P < 0.05). When subjects were categorized by both CYP1A1 genotype and GSTM1 genotype, GSTM1 (-) became markedly expressed in patients with CYP1A1 (I/I) than in the corresponding controls (67% versus 40%, P < 0.01). The frequency of CYP1A1 genotype with at least one allele of Val (I/V and V/V) was also statistically higher in patients with GSTM1 (+), comparing to the corresponding controls (64% versus 41%, P < 0.05). CONCLUSIONS: It was suggested that: genetic polymorphisms of CYP1A1 and GSTM1 were susceptible to esophageal cancer; individuals who are GSTM1-null have an increased risk of developing esophageal cancer; individuals with combined CYP1A1 (I/I) and GSTM1 (-) or with combined CYP1A1 (I/V, V/V) and GSTM1 (+) were more susceptible, when comparing to those with combined CYP1A1 (I/I) and GSTM1 (+).

Adult↗
PubMed1999

Raloxifene and estradiol benzoate both fully restore hippocampal choline acetyltransferase activity in ovariectomized rats.

Selective estrogen receptor modulators (SERMs) demonstrate tissue-specific estrogen receptor (ER) agonist or antagonist properties. Raloxifene, a prototypical SERM, has ER agonist properties in bone and on cholesterol metabolism but full antagonist properties in the uterus and breast. To characterize the ER agonist/antagonist profile of raloxifene in the brain, we have examined its effect on the activity of a known estrogen-responsive gene product, choline acetyltransferase (ChAT), in the hippocampus and other brain regions of 6-month-old ovariectomized (OVX) Sprague-Dawley rats. Three weeks post-ovariectomy, animals received estradiol benzoate (EB, 0.03 mg or 0.3 mg kg(-1) day(-1) for 3 or 10 days); raloxifene HCl (3.0 mg kg(-1) day(-1) for 3 or 10 days), tamoxifen (3.0 mg kg(-1) day(-1) for 10 days) or vehicle (20% CDX). As previously reported, ChAT activity decreased by approximately 20%-50% in the hippocampus of OVX compared with SHAM-operated control rats with no change in ChAT activity observed in the hypothalamus. Raloxifene or EB reversed the OVX-induced decrease in ChAT activity in the hippocampus but did not change ChAT activity in the hypothalamus. Animals that received combined EB (0.03 mg/kg) plus raloxifene (1 mg/kg) or tamoxifen alone (3.0 or 10 mg/kg) also showed increased hippocampal ChAT activity. Raloxifene failed to increase uterine weight and blocked the estrogen-induced increase in uterine weight, while another SERM, tamoxifen, increased uterine weight. These data demonstrate that raloxifene has estrogen-like properties on hippocampal ChAT activity in vivo, and suggest that benzothiophene SERMs may exert estrogen-like beneficial effects on cholinergic neurotransmission in brain without producing peripheral stimulation of breast or uterine tissue.

Alzheimer Disease↗
PubMed1999

Assay of 6-mercaptopurine and its metabolites in patient plasma by high-performance liquid chromatography with diode-array detection.

A reversed-phase high-performance liquid chromatography (HPLC) method was developed to determine 6-mercaptopurine (MP) and seven of its metabolites (6-thioguanine, 6-thioxanthine, 6-mercaptopurine riboside, 6-thioguanosine, 6-thioxanthine riboside, 6-methylmercaptopurine and 6-methylmercaptopurine riboside) simultaneously in human plasma. A volume of 100 microl of plasma was used. Protein was removed from the sample by a simple and easy ultrafiltration step and ultrafiltrate was directly injected onto the HPLC system. Analytes were detected and confirmed with a diode-array detector before quantitation at 295 and 330 nm. The limit of detection for the analytes ranged from 20 to 50 nM. For the majority of patients receiving a 1 g/m2 MP intravenous infusion, MP and all metabolites except 6-thioguanine and 6-methylmercaptopurine riboside were present. This method serves as useful tool to characterize pharmacokinetics and pharmacodynamics of MP in oncology patients, and the small volume of plasma lends itself to pediatric studies.

Antimetabolites, Antineoplastic↗
PubMed1999

Candidate EPA, NIOSH method for determining carbon disulfide in air with capillary gas chromatography by orthogonal design.

This paper describes a candidate NIOSH EPA method for the determination of carbon disulfide in the air of workplaces with capillary gas chromatography using an orthogonal design. This method is designed to replace the packed column of the NIOSH method with a capillary column. The first part of this work concerned the setup of the method, particularly the choice of chromatographic parameters and finding their main favorable working ranges. The second part, using the statistical method orthogonal design, focused on optimizing the GC conditions, which were: column temperature, T(c) = 90 degrees C; injector temperature, T(i) = 140 degrees C; U section detector temperature, FPDU = 160 degrees C; L section detector temperature, FPDL = 210 degrees C; flow rate of carrier gas, F(c) = 20 cm/s; split ratio = 1/70; and injection volume = 1 microL. The quality control test showed that the coefficient of intra-day variation (CV) was 2.21%. A good logarithm linear correlation between the standard solutions and their peak areas was obtained. In general, the method reported here seems a valid candidate for a NIOSH EPA method due to its high precision and accuracy.

Air Pollutants↗
PubMed1999

Study on relationship between carbon disulfide exposure and symptoms and signs of nervous system in workers.

The relationship between carbon disulfide (CS2) and the symptoms and signs of nervous system in rayon workers was investigated. In a cross sectional study of CS2-exposed workers from the viscose industry and controls, data on neurological symptoms and clinical neurological examination were evaluated. The exposed subjects includes 326 workers and 105 workers from the same factory, without exposure to CS2 or to any other neurotoxic agents, served as controls. The median exposure to CS2(8 h time weighted) in the low-level exposure group was 4.6 mg/m3, and 18.3 mg/m3 in high-level exposure group. Non-conditional multiple logistic regression analysis was employed for evaluating statistical differences by using SAS software. In the analysis, age, sex, work time, body mass index (BMI), smoking and drinking habits, educational background and marriage status were controlled. The odds ratio (OR) significantly increased of some symptoms in workers exposed to CS2 at levels below 10 mg/m3, as compared to controls. The dose-effect relationship between the exposure to CS2 and the symptoms of nervous system was demonstrated. In terms of neurological parameters, no other abnormal change but that in temperature sensitivity was observed in workers exposed to CS2. In conclusion, the influence of low level CS2 on nervous system of workers should not be ignored.

Carbon Disulfide↗