Biomedical subjects

M Ye

Publications and source records attributed to M Ye.

At least 19 recordsLinked to original sources

PubMed2001

Capillary electrochromatography for separation of peptides driven with electrophoretic mobility on monolithic column.

A mode of capillary electrochromatography for separation of ionic compounds driven by electrophoretic mobility on a neutrally hydrophobic monolithic column was developed. The monolithic column was prepared from the in situ copolymerization of lauryl methacrylate and ethylene dimethacrylate to form a C12 hydrophobic stationary phase. It was found that EOF in this hydrophobic monolithic column was very poor, even the pH value of mobile phase at 8.0. The peptides at acidic buffer were separated on the basis of their differences in electrophoretic mobility and hydrophobic interaction with the stationary phase; therefore, different separation selectivity can be obtained in CEC from that in capillary zone electrophoresis (CZE). Separation of peptides has been realized with high column efficiency (up to 150,000 plates/meter) and good reproducibility (migration time with RSD <0.5%), and all of the peptides, including some basic peptides, showed good peak symmetry. Effects of the mobile phase compositions on the retention of peptides at low pH have been investigated in a hydrophobic capillary monolithic column. The significant difference in selectivity of peptides in CZE and CEC has been observed. Some peptide isomers that cannot be separated by CZE have been successfully separated on the capillary monolithic column in this mode with the same buffer used.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2001

Metabolites of a tobacco-specific lung carcinogen in nonsmoking women exposed to environmental tobacco smoke.

BACKGROUND: Environmental tobacco smoke (ETS) is associated with lung cancer in nonsmokers. Most epidemiologic studies find a higher risk for lung cancer in nonsmoking women married to smokers than in those married to nonsmokers. We measured metabolites of a tobacco-specific lung carcinogen in urine from healthy, nonsmoking women exposed to ETS. METHODS: We recruited women and their partners through advertisements. Couples completed questionnaires on smoking history and demographics, and both partners provided 100 mL of urine; 23 women had male partners who smoked in the home (i.e., exposed women), and 22 women had male partners who did not smoke (i.e., unexposed women). Urine samples were analyzed for nicotine, for cotinine, for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronide (NNAL-Gluc), as well as for creatinine. NNAL and NNAL-Gluc are metabolites of the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Unpaired Student's t tests were conducted on log-transformed values. All statistical tests are two-sided. RESULTS: Urinary levels of nicotine, cotinine, NNAL, and NNAL-Gluc were statistically significantly higher in exposed women than in unexposed women. Geometric means for these compounds in exposed versus unexposed women, respectively, were as follows: nicotine, 0.050 nmol/mg of creatinine (95% confidence interval [CI] = 0.033 to 0.076) versus 0.008 nmol/mg of creatinine (95% CI = 0.004 to 0.014); cotinine, 0.037 nmol/mg of creatinine (95% CI = 0.022 to 0.061) versus 0.007 nmol/mg of creatinine (95% CI = 0.004 to 0.011); NNAL, 0.013 pmol/mg of creatinine (95% CI = 0.007 to 0.024) versus 0.004 pmol/mg of creatinine (95% CI = 0.002 to 0.007); and NNAL-Gluc, 0.027 pmol/mg of creatinine (95% CI = 0.016 to 0.045) versus 0.004 pmol/mg of creatinine (95% CI = 0.003 to 0.006). CONCLUSIONS: Nonsmoking women exposed to ETS take up and metabolize the tobacco-specific lung carcinogen NNK, which could increase their risk of lung cancer. Within couples, the NNAL plus NNAL-Gluc level in exposed women compared with that of their smoking partners averaged 5.6%. Notably, epidemiologic studies have estimated the excess risk for lung cancer in nonsmoking women exposed to ETS as 1%-2% of that in smokers.

Adult↗

PubMed2001

Enantiomer separation by strong anion-exchange capillary electrochromatography with dynamically modified sulfated beta-cyclodextrin.

A novel mode of capillary electrochromatography (CEC) based on a dynamically modified stationary phase was presented for chiral separation. The capillary column was packed with strong anion-exchange (SAX) stationary phase packing; the sulfated beta-cyclodextrin (S-CD), which was added to the mobile phase, was dynamically adsorbed to the packing surface. Separation of enantiomers was achieved by their different abilities to form an inclusion complex with the adsorbed S-CD. The enantiomers of tryptophan, praziquantel, atropine, metoprolol, and verapamil were successfully separated in this system with a column efficiency of 36000-412000 plates/m. The resolution value obtained for atropine was as high as 11.23. The superiority of CEC with a dynamically modified stationary phase over that with a physically adsorbed stationary phase was demonstrated. The influence of ionic strength, S-CD concentration, and methanol content on separation was also studied.

Anions↗

PubMed2001

Separation of basic, acidic and neutral compounds by capillary electrochromatography using uncharged monolithic capillary columns modified with anionic and cationic surfactants.

A mode of capillary electrochromatography (CEC), based on the dynamical adsorption of surfactants on the uncharged monolithic stationary phases has been developed. The monolithic stationary phase, obtained by the in situ polymerization of butyl methacrylate with ethylene dimethacrylate, was dynamically modified with an ionic surfactant such as the long-chain quaternary ammonium salt of cetyltrimethylammonium bromide (CTAB) and long-chain sodium sulfate of sodium dodecyl sulfate (SDS). The ionic surfactant was adsorbed on the surface of polymeric monolith by hydrophobic interaction, and the ionic groups used to generate the electroosmotic flow (EOF). The electroosmotic mobility through these capillary columns increased with increasing the content of ionic surfactants in the mobile phase. In this way, the synthesis of the monolithic stationary phase with binary monomers can be controlled more easily than that with ternary monomers, one of which should be an ionic monomer to generate EOF. Furthermore, it is more convenient to change the direction and magnitude of EOF by changing the concentration of cationic or anionic surfactants in this system. An efficiency of monolithic capillary columns with more than 140000 plates per meter for neutral compounds has been obtained, and the relative standard deviations observed for to and retention factors of neutral solutes were about 0.22% and less than 0.56% for ten consecutive runs, respectively. Effects of mobile phase composition on the EOF of the column and the retention values of the neutral solutes were investigated. Simultaneous separation of basic, neutral and acidic compounds has been achieved.

Anions↗

PubMed2001

Separation of 4-dimethylamino-6-(4-methoxy-1-naphthyl)-1,3,5-triazine-2-hydrazine derivatives of carbonyl compounds by reversed-phase capillary electrochromatography.

4-Dimethylamino-6-(4-methoxy-1-naphthyl)-1,3,5-triazine-2-hydrazine (DMNTH) is a novel derivatizing reagent specially designed for the determination of carbonyl compounds. In this work, we describe the separation of DMNTH-derivatized carbonyl compounds by reversed-phase capillary electrochromatography (CEC). After systematic investigations of the effects of experimental conditions viz. pH and concentration of buffer, type of stationary phase, injection volume of sample, organic modifier, and temperature, optimal conditions were found. The sample compounds, which were separated with gradient high performance liquid chromatography (HPLC), were separated by CEC under isocratic elution due to the high efficiency. Comparisons of separations by CEC and micellar electrokinetic chromatography (MEKC) were made.

Carbonic Acid↗

PubMed2001

Hypotonic swelling-induced Ca(2+) release by an IP(3)-insensitive Ca(2+) store.

Hypotonic swelling increases the intracellular Ca(2+) concentration ([Ca(2+)](i)) in vascular smooth muscle cells (VSMC). The source of this Ca(2+) is not clear. To study the source of increase in [Ca(2+)](i) in response to hypotonic swelling, we measured [Ca(2+)](i) in fura 2-loaded cultured VSMC (A7r5 cells). Hypotonic swelling produced a 40.7-nM increase in [Ca(2+)](i) that was not inhibited by EGTA but was inhibited by 1 microM thapsigargin. Prior depletion of inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca(2+) stores with vasopressin did not inhibit the increase in [Ca(2+)](i) in response to hypotonic swelling. Exposure of (45)Ca(2+)-loaded intracellular stores to hypotonic swelling in permeabilized VSMC produced an increase in (45)Ca(2+) efflux, which was inhibited by 1 microM thapsigargin but not by 50 microg/ml heparin, 50 microM ruthenium red, or 25 microM thio-NADP. Thus hypotonic swelling of VSMC causes a release of Ca(2+) from the intracellular stores from a novel site distinct from the IP(3)-, ryanodine-, and nicotinic acid adenine dinucleotide phosphate-sensitive stores.

Animals↗

PubMed2001

[Collecting of trichloroaniline in the air by micropore filter membrane and determination by gas chromatography].

Trichloroaniline in the air was collected with micropore filter membrane and desorbed with cyclohexane, separated with a column OV-17, OV-210 and determined by GC-ECD. The materals for the filter of collection, solution of desorping and flow-rate of sampling were selected. The detectable limit is 0.01 mg/L. When the concentration of standard solutions is 1-10 mg/L, the relative standard deviation (RSD) is 4.5%-2.3%. There is a linear relation within the range of 0.005-30 mg/L. The sampling efficiency is 98.7%-100%. The samplers were stable for at least 15 days. This method is proved to be accurate, sensitive, fast and simple for sampling and carrying, and it is method is suitable for the determination of trichloroaniline in air, for personal detection and detection in the fields.

Air Pollutants↗

PubMed2001

[Identification of seeds of Cuscuta australis and C. chinensis by TLC and HPLC].

Identification of seeds of Cuscuta australis R. Br. and C. chinensis Lam. was carried out by TLC and HPLC. Polyamide membrane was used as stationary phase, MeOH-HOAc-H2O and CHCl3-MeOH-HOAc were used as mobile phase for TLC. For HPLC, Hypersil-ODS column was used; the mobile phase was MeOH-0.025 M H3PO4; the flow rate was 1.0 ml.min-1; detection wavelength was 360 nm; and column temperature was 40 degrees C. Both methods represented significant identification characteristics, and were simple, accurate and reproducible.

Chromatography, High Pressure Liquid↗

PubMed2001

Metabolites of a tobacco-specific lung carcinogen in the urine of elementary school-aged children.

Limited data are available in the literature on carcinogen uptake by children exposed to environmental tobacco smoke (ETS). In this study, we quantified metabolites of the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in the urine of elementary school-aged children participating in the School Health Initiative: Environment, Learning, Disease study, a school-based investigation of the environmental health of children. The metabolites of NNK are 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronide (NNAL-Gluc). We also measured cotinine and its glucuronide (total cotinine). Urine samples were collected from 204 children. Seventy (34.3%) of these had total cotinine > or =5 ng/ml. NNAL or NNAL-Gluc was detected in 52 of 54 samples with total cotinine > or =5 ng/ml and in 10 of 20 samples with total cotinine < 5 ng/ml. Levels of NNAL plus NNAL-Gluc and total cotinine were significantly higher when exposure to ETS was reported than when no exposure was reported. However, even when no exposure to ETS was reported, levels of NNAL, NNAL-Gluc, and NNAL plus NNAL-Gluc were higher than in children with documented low exposure to ETS, as determined by cotinine levels < 5 ng/ml. Levels of NNAL, NNAL-Gluc, and cotinine were not significantly different in samples collected twice from the same children at 3-month intervals. Levels of NNAL plus NNAL-Gluc in this study were comparable with those observed in our previous field studies of adults exposed to ETS. There was a 93-fold range of NNAL plus NNAL-Gluc values in the exposed children. The results of this study demonstrate widespread and considerable uptake of the tobacco-specific lung carcinogen NNK in this group of elementary school-aged children, raising important questions about potential health risks. Our data indicate that objective biomarkers of carcinogen uptake are important in studies of childhood exposure to ETS and cancer later in life.

Biomarkers↗

PubMed2001

Roles of IL-4 and other factors in the trichosanthin-induced ovalbumin-specific IgE response.

AIM: To study the mechanism of trichosanthin (TCS)-induced ovalbumin (OVA)-specific immunoglobulin E (IgE) response in vivo. METHODS: To determine whether interleukin-4 (IL-4) was involved in TCS-induced IgE production, TCS and OVA co-immunized mice were treated with anti-IL-4 monoclonal antibodies (mAb) and OVA-specific serum IgE production was measured by enzyme-linked immunosorbent assay (ELISA). To distinguish whether recombinant IL-4 (rIL-4) was sufficient to support OVA-specific IgE response, OVA alone immunized mice were treated with rIL-4 and OVA-induced IgE production were examined by ELISA in the serum. To determine whether additional factors were involved in TCS-induced IgE response, th e kinetic expression of CD40 ligand (CD40L), tumor necrosis factor-alpha (TNF-alpha), and interleukin-13 (IL-13) were measured by semi-quantitative RT-PCR in draining mesenteric lymph node (MLN) from TCS-immunized mice. RESULTS: TCS-induced OVA-specific IgE production was suppressed by anti-IL-4 antibody, whereas IL-4 alone could not induce OVA-specific IgE production. CD40L, TNF-alpha, and IL-13 all expressed high levels in MLN after both primary and secondary immune responses. Among them CD40L had the similar transient expression peak to that of IL-4. CONCLUSION: IL-4 was indispensable for TCS-induced OVA-specific IgE production, and the other three factors examined may also be involved in, but CD40L may play a more important role.

Animals↗

PubMed2001

[Accelerated hyperfractionation radiation therapy combined with chemotherapy for non-small cell lung cancer complicated with superior vena cava syndrome].

OBJECTIVE: This retrospective study was done to evaluate the patient's tolerance and effect of accelerated hyperfractionation radiation therapy in the treatment of superior vena cava syndrome (SVCS) caused by non-small cell lung cancer (NSCLC). METHODS: Thirty-four NSCLC patients complicated with SVCS were treated between January 1992 and September 1996. Their ages ranged from 36-78 years (median 57). There were 30 (88.2%) male and 4(11.8%) female patients. Dyspnea (67.6%) and facial swelling (52.9%) were the two most common symptoms. Engorgement of neck veins (38.2%) and dilated chest wall veins (28.5%) were the most common physical findings. According to their pathological diagnosis, there were 17(50%) squamous cell carcinomas, 14(41.2%) adenocarcinomas, 2(5.9%) mixed squamous and adenocarcinomas and 1(2.96%) poorly differentiated carcinomas. By thoracic CT scans, a mass was most commonly found in the right upper lobe and the upper mediastinum. For these patients, chemotherapy IEP or IAP (IFO 2.0 g d1-4, DDP 40 mg d1-3, Vp-16 0.1 g d1-3 or ADM 50 mg d1) was given first. Twenty-four to 72 hours after chemotherapy, accelerated hyperfractionation radiation therapy was started to deliver to the primary tumor and the metastatic mediastinal lymph nodes, a tumor dose of 30 Gy/20 fx/2 wk followed by a boost to 36-40.8 Gy/30-34 fx/3-3.5 wk. Diuretics, steroids and dehydrating agents were concomittantly prescribed during the radiation therapy. RESULTS: Relief of SVCS to various degrees was noted in all patients. CR, PR and MR rates were 20.6% (7/34), 50% (17/34) and 29.4% (10/34), respectively. The median survival was 12 months (4-26 months). The 1-2 year actuarial survival rates were 58.1% and 18.2% Except radio-esophagitis in different degrees, no other severe complications were observed. CONCLUSION: The fraction and total dose of radiotherapy are tolerable in this accelerated hyperfractionation trial. Radiation therapy combined with chemotherapy gives similar results as non-surgery for stage III NSCLC. No significant difference in the survival rates of the various histological types is observed.

Adenocarcinoma↗

PubMed2001

[Palliative irradiation combined with chemotherapy for lung cancer with brain metastasis].

OBJECTIVE: To evaluate to effects and complications of palliative irradiation combined with chemotherapy for lung cancer with brain metastasis. METHODS: Eighty-two non-small cell lung cancer with brain metastasis were treated, of whom 48 had extracranial metastasis simultaneously. All patients received chemotherapy (Teniposide and cis-platin) prior to and also after radiotherapy. The multiple-intracranial metastasis patients received whole brain radiation therapy to a dose of 33-39 Gy/11-13 fx. The others who had single intracranial lesion received whole brain irradiation of 30 Gy/10 fx and a boost of 15 Gy/5 fx. RESULTS: The overall 1- and 2-year actuarial survival rates were 46.7% and 6.7%. For patients with brain metastasis and extracranial lesions, the 1- and 2-year survival rates were 32.4% and 4.4%. For patients with intracranial metastasis only, they were 61.2% and 8.8%, respectively (P = 0.003). The median survival of these two groups were 8 and 12 months. There was no significant correlation between the survivals rate and the histological type or the number of intracranial metastasis. No severe complications were observed during the treatment and follow-up. CONCLUSION: The regimen of combined chemotherapy with radiotherapy is effective for lung cancer with brain metastasis. The survival rate of patients with intracranial metastasis only is obviously higher than those with multiple extracranial lesions in addition to brain metastasis.

Adult↗

PubMed2001

[Studies on the chemical constituents of the herba of Cuscuta chinensis].

The chemical constituents of the herb of Cuscuta chinensis Lam. were investigated. Five compounds were isolated from petroleum ether and chloroform fraction. Their structures were identified as beta-sitosterol, d-sesamin, 9(R)-hydroxy-d-sesamin, d-pinoresinol and daucosterol by chemical and spectroscopical methods. All these compounds were isolated from the stem for the first time.

Chemical Fractionation↗

PubMed2000

Microdialysis sampling of the isothiazolone, PD-161374, and its thiol and disulfide metabolites.

A method based on microdialysis sampling combined with high-performance liquid chromatography (HPLC) has been developed for monitoring the anti-HIV agent PD-161374 (isothiazolone) and its thiol and disulfide metabolites in blood. It was demonstrated that unlike blood withdraw and extraction, microdialysis sampling can preserve the distribution among the isothiazolone and its metabolites in blood. The use of a narrow-bore HPLC system, combined with the relatively high probe extraction efficiency (approximately 50%) from the flexible probe design in this work, allows the direct and quantitative determination of the drug and its major metabolites at submicromolar level.

Animals↗

PubMed2000

Gene expression profiling in the human hypothalamus-pituitary-adrenal axis and full-length cDNA cloning.

The primary neuroendocrine interface, hypothalamus and pituitary, together with adrenals, constitute the major axis responsible for the maintenance of homeostasis and the response to the perturbations in the environment. The gene expression profiling in the human hypothalamus-pituitary-adrenal axis was catalogued by generating a large amount of expressed sequence tags (ESTs), followed by bioinformatics analysis (http://www.chgc.sh.cn/ database). Totally, 25,973 sequences of good quality were obtained from 31,130 clones (83.4%) from cDNA libraries of the hypothalamus, pituitary, and adrenal glands. After eliminating 5,347 sequences corresponding to repetitive elements and mtDNA, 20,626 ESTs could be assembled into 9, 175 clusters (3,979, 3,074, and 4,116 clusters in hypothalamus, pituitary, and adrenal glands, respectively) when overlapping ESTs were integrated. Of these clusters, 2,777 (30.3%) corresponded to known genes, 4,165 (44.8%) to dbESTs, and 2,233 (24.3%) to novel ESTs. The gene expression profiles reflected well the functional characteristics of the three levels in the hypothalamus-pituitary-adrenal axis, because most of the 20 genes with highest expression showed statistical difference in terms of tissue distribution, including a group of tissue-specific functional markers. Meanwhile, some findings were made with regard to the physiology of the axis, and 200 full-length cDNAs of novel genes were cloned and sequenced. All of these data may contribute to the understanding of the neuroendocrine regulation of human life.

Alternative Splicing↗

PubMed2000

Separation of acidic compounds by strong anion-exchange capillary electrochromatography.

Separation of the acidic compounds in the ion-exchange capillary electrochromatography (IE-CEC) with strong anion-exchange packing as the stationary phase was studied. It was observed that the electroosmotic flow (EOF) in strong anion-exchange CEC moderately changed with increase of the eluent ionic strength and decrease of the eluent pH, but the acetonitrile concentration in the eluent had almost no effect on the EOF. The EOF in strong anion-exchange CEC with eluent of low pH value was much larger than that in RP-CEC with Spherisorb-ODS as the stationary phase. The retention of acidic compounds on the strong anion-exchange packing was relatively weak due to only partial ionization of them, and both chromatographic and electrophoretic processes contributed to separation. It was observed that the retention values of acidic compounds decreased with the increase of phosphate buffer and acetonitrile concentration in the eluent as well as the decrease of the applied voltage, and even the acidic compounds could elute before the void time. These factors also made an important contribution to the separation selectivity for tested acidic compounds, which could be separated rapidly with high column efficiency of more than 220000 plates/m under the optimized separation conditions.

Acetonitriles↗

PubMed2000

Separation of peptides by strong cation-exchange capillary electrochromatography.

Separation of small peptides on ion-exchange capillary electrochromatography (IE-CEC) with strong cation-exchange packing (SCX) as stationary phase was investigated. It was observed that the number of theoretical plates for small peptides varied from 240000 to 460000/m, and the relative standard deviation for t0 and the migration time of peptides were less than 0.57% and 0.27%, respectively for ten consecutive runs. Unusually high column efficiency has been explained by the capillary electrophoretic stacking and chromatofocusing phenomena during the injection and separation of positively charged peptides. The sample buffer concentration had a marked effect on the column efficiency and peak area of the retained peptides. The influences of the buffer concentration and pH value as well as the applied voltage on the separation were investigated. It has been shown that the electrostatic interaction between the positively charged peptides and the SCX stationary phase played a very important role in IE-CEC, which provided the different separation selectivity from those in the capillary electrophoresis and reversed-phase liquid chromatography. A fast separation of ten peptides in less than 3.5 min on IE-CEC by adoption of the highly applied voltage was demonstrated.

Buffers↗

PubMed2000

Capillary electrochromatography using a strong cation-exchange column with a dynamically modified cationic surfactant

A novel mode of capillary electrochromatography (CEC), called dynamically modified strong cation-exchange CEC (DMSCX-CEC), is described in this paper. A column packed with a strong cation-exchange (SCX) packing material was dynamically modified with a long-chain quaternary ammonium salt, cetyltrimethylammonium bromide (CTAB), which was added to the mobile phase. CTAB ions were adsorbed onto the surface of the SCX packing material, and the resulting hydrophobic layer on this packing was used as the stationary phase. Using the dynamically modified SCX column, neutral solutes were separated with the CEC mode. The highest number of theoretical plates obtained was about 190,000/m, and the relative standard deviations (RSD's) for migration times and capacity factors of alkylbenzenes were less than 1.0% and 2.0% for five consecutive runs, respectively. The effects of CTAB and methanol concentrations and the pH value of the mobile phase on the electroosmotic flow and the separation mechanism were investigated. Excellent simultaneous separation of the basic and neutral solutes in DMSCX-CEC with a high-pH mobile phase was obtained. A mixture containing the acidic, basic, and neutral compounds was well separated in this mode with a low-pH mobile phase; however, peak tailing for basic compounds was observed in this mobile phase.

Journal Article↗