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Yun Chen

Publications and source records attributed to Yun Chen.

At least 37 records · Page 2Linked to original sources
PubMed2006

Individual acidic organelle pH measurements by capillary electrophoresis.

This report describes the pH measurement of individual acidic organelles isolated from the human leukemia CCRF-CEM and CEM/C2 cells. These cells were allowed to endocytose fluorescein tetramethylrhodamine dextran (FRD), a ratiometric probe that has fluorescein as a pH-dependent fluorophore and tetramethylrhodamine as a pH-independent fluorophore. Isolated organelle fractions from these cells were then subjected to capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) analysis. The detection of individual organelle fluorescence at two different wavelengths, selected on the basis of the emission range of the FRD probe, gives a fluorescence intensity ratio used to calculate the pH from a calibration curve. This curve was constructed from CE-LIF measurements of individual liposomes loaded with several pH buffer standards. The respective median pH values are 5.1 +/- 0.2 in CEM/C2 cells and 6.1 +/- 0.4 in CCRF-CEM cells. These measurements compare well with pixel-based epifluorescence microscopy measurements of whole cells where the corresponding average pH values are 5.0 +/- 0.6 (n = 15) and 6.2 +/- 0.7 (n = 15). A pH comparison between the two cell types suggests that the lower pH in the CEM/C2 cells may be relevant to the protonation and sequestration of weak base anticancer drugs such as doxorubicin. The determination of the pH of individual vesicles, liposomes, and acidic organelles is a new resource for measuring and investigating the role of the acid-base properties of subcellular-size compartments.

Cell Line, Tumor↗
PubMed2006

STAT6 specific shRNA inhibits proliferation and induces apoptosis in colon cancer HT-29 cells.

RNA interference (RNAi) has been employed as an effective tool for studying gene functions. Here, we have demonstrated that different short hairpin RNAs (shRNAs) can specifically knock-down the transcription of STAT6, resulting in the inhibition of cell proliferation, G1/S phase arrest and apoptotic death in colon cancer HT-29 cells. These findings suggest that Stat6 signaling pathway plays a role in the regulation of cell proliferation and apoptosis in colon cancer cells, which promises further investigation for targeted cancer therapy.

Apoptosis↗
PubMed2006

Composite coating of bonelike apatite particles and collagen fibers on poly L-lactic acid formed through an accelerated biomimetic coprecipitation process.

Collagen and apatite were coprecipitated as a composite coating on poly L-lactic acid (PLLA) in an accelerated biomimetic process. The incubation solution contained collagen (1 g/L) and simulated body fluid with 5 times inorganic ionic concentrations as human blood plasma. The coating formed on PLLA films and scaffolds after a 24-h incubation was characterized by using energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy (SEM). It was shown that the coating contained carbonated bonelike apatite and collagen, which was similar in composition to natural bone. SEM showed a complex composite coating of submicron bonelike apatite particulates combined with collagen fibrils. It is expected that such biocomposite coating may better facilitate cell interaction and osteoconductivity. This work provided an efficient process to obtain bonelike apatite/collagen composite coating, which is potentially useful in bone tissue engineering.

Apatites↗
PubMed2006

Simultaneous determination of spironolactone and its active metabolite canrenone in human plasma by HPLC-APCI-MS.

A sensitive and specific liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) method for the simultaneous determination of spironolactone and its active metabolite canrenone in human plasma has been developed and validated. After the addition of estazolam as the internal standard (IS), plasma samples were extracted with methylene chloride : ethyl acetate mixture (20 : 80, v/v) and separated by high-performance liquid chromatography (HPLC) on a reversed-phase C18 column with a mobile phase of methanol-water (57 : 43, v/v). Analytes were determined in a single quadrupole mass spectrometer using an atmospheric pressure chemical ionization (APCI) source. LC-APCI-MS was performed in the selected-ion monitoring (SIM) mode using target ions at m/z 341.25 for spironolactone and canrenone, m/z 295.05 for estazolam. The method was proved to be sensitive and specific by testing six different plasma batches. Calibration curves of spironolactone and canrenone were linear over the range 2-300 ng/ml. The within- and between-batch precisions (relative standard deviation (RSD)%) were lower than 10% and the accuracy ranged from 85 to 115%. The lower limit of quantification (LLOQ) was identifiable and reproducible at 2 ng/ml. The proposed method was successfully applied to study the pharmacokinetics of spironolactone and its major metabolite in healthy male Chinese volunteers.

Blood Chemical Analysis↗
PubMed2006

Quantification of fudosteine in human plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry employing precolumn derivatization with 9-fluorenylmethyl chloroformate.

This paper describes a novel method for the sensitive and selective determination of fudosteine in human plasma. The method involves a derivatization step with 9-fluorenylmethyl chloroformate (FMOC-Cl) in borate buffer and detection based on high-performance liquid chromatography-electrospray ionization mass spectrometry (LC/ESI/MS). After acetonitrile-induced protein precipitation of plasma samples, fudosteine was derivatized with FMOC-Cl, then extracted by ethyl acetate, evaporated, reconstituted and injected using an LC/ESI/MS instrument. Separation was achieved using an ODS column and isocratic elution. Excellent linearity was obtained for the entire calibration range from 0.05 to 20 microg/ml. Validation assays of the lower limit of quantification (LLOQ) as well as for the intra- and inter-batch precision and accuracy met the international acceptance criteria for bioanalytical method validation. Using the developed analytical method, fudosteine could be detected for the first time in human plasma with a low limit of detection (LLOD) of 0.03 microg/ml. The proposed method has been successfully applied to study the pharmacokinetics of fudosteine in healthy Chinese volunteers after single and multiple oral administration.

Administration, Oral↗
PubMed2006

Pituitary abscess.

Pituitary abscess is a rare disease, but one with potentially high mortality and morbidity. We present a 46-year-old man with progressive visual disturbance and general malaise for 1 year. Endocrine studies revealed hypopituitarism, and magnetic resonance imaging revealed a pituitary lesion with suprasellar extension. We attempted to excise the lesion using a transsphenoidal approach, but pus in the pituitary fossa was found at operation, and no tumour was identified. The culture yielded coagulase-negative Staphylococcus. Antibiotics were administered for 3 weeks, and the patient made a good postoperative recovery. He required life-long hormone replacement therapy. After one and a half years of follow-up, he was well and had no evidence of focal or systemic infection. We review the literature regarding pituitary abscess and discuss the appropriate treatment and possible pathological mechanism.

Anti-Bacterial Agents↗
PubMed2006

Laparoscopic Nissen fundoplication without division of short gastric vessels in children.

PURPOSE: It has been suggested that routine division of short gastric vessels (SGVs) results in a more "floppy" Nissen fundoplication leading to improved outcomes, that is, less dysphagia and lower incidences of recurrent gastroesophageal reflux disease (GERD). The aim of this retrospective study was to assess whether laparoscopic Nissen fundoplication without division of SGVs (Rossetti modification) (laparoscopic Nissen-Rossetti fundoplication [LNRF]) is associated with acceptable clinical outcome in children. METHOD: The charts of 368 children who underwent LNRF between January 1996 and September 2004 by 1 primary surgeon were retrospectively reviewed. Children were divided into 2 groups: LNRF + gastrostomy (A) and LNRF alone (B). Mean follow-up period of all groups was 4.2 years. RESULTS: Laparoscopic Nissen-Rossetti fundoplication was completed in 99% (365/368). Mean operating time for group A was 74 minutes and 61 minutes for group B. None in group A required postoperative esophageal dilatation, and 9 in group B (22.5%) required 12 dilatations; 3.6% developed recurrent GERD, 3.7% in group A and 2.5% in group B. CONCLUSION: Laparoscopic Nissen-Rossetti fundoplication can be performed with acceptable long-term outcome in children, especially in the majority also requiring chronic gastrostomy access. Short-term, reversible dysphagia may be seen in a small percentage of children having fundoplication alone.

Adolescent↗
PubMed2006

Methods to measure the lateral diffusion of membrane lipids and proteins.

In this chapter, we discuss methods to measure lateral mobility of membrane lipids and proteins using techniques based on the light microscope. These methods typically sample lateral mobility in very small, micron-sized regions of the membrane so that they can be used to measure diffusion in regions of single cells. The methods are based on fluorescence from the molecules of interest or from light scattered from particles attached to single or small groups of membrane lipids or proteins. Fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS) and Single particle tracking (SPT) are presented in that order. FRAP and FCS methodologies are described for a dedicated wide field microscope although many confocal microscopes now have software permitting these measurement to be made; nevertheless, the principles of the measurement are the same for a wide field or confocal microscope. SPT can be applied to trace the movements of single fluorescent molecules in membranes but this aspect will not be treated in detail.

Biochemistry↗
PubMed2006

Human herpesvirus-6-specific interleukin 10-producing CD4+ T cells suppress the CD4+ T-cell response in infected individuals.

Human herpesvirus-6 (HHV-6) infection normally persists for the lifetime of the host and may reactivate with immunosuppression. The mechanism behind HHV-6 latent infection is still not fully understood. In this study, we observed that decreased proliferation of CD4+ T cells and PBMCs but not CD8+ T cells from HHV-6-infected individuals was stimulated with HHV-6-infected cell lysates. Moreover, HHV-6-stimulated CD4+ T cells from HHV-6-infected individuals have suppressive activity on naïve CD4+ T and CD8+ T cells from HHV-6-uninfected individuals. However, no increased proportion of CD4+ CD25+ Treg cells from HHV-6-infected individuals contributed to the suppressive activity of the HHV-6-stimulated CD4+ T cells from HHV-6-infected individuals. Transwell experiments, ELISA and anti-IL-10 antibody blocking experiment demonstrated that IL-10 may be the suppressive cytokine required for suppressive activity of CD4+ T cells from HHV-6-infected individuals. Results of intracellular interleukin (IL)-10 and IL-4 further implicated the HHV-6-specific IL-10-producing CD4+ T cells in the suppressive activity of CD4+ T cells from HHV-6-infected individuals. Results of intracellular interferon (IFN)-gamma demonstrated a decreased frequency of HHV-6-specific IFN-gamma-producing CD4+ T, but not CD8+ T cells in HHV-6-infected individuals, indicating that it was the CD4+ Th1 responses in HHV-6-infected individuals that were selectively impaired. Our findings indicated that HHV-6-specific IL-10-producing CD4+ T cells from HHV-6-infected individuals possess T regulatory type 1 cell activity: immunosuppression, high levels of IL-10 production, with a few cells expressing IFN-gamma, but none expressing IL-4. These cells may play an important role in latent HHV-6 infection.

Adult↗
PubMed2006

Further insights into the role of angiotensin II in kidney development.

Over the past decade, compelling studies have highlighted the fundamental role of the renin-angiotensin system (RAS) in renal development and long-term control of renal function and arterial pressure. The present review provides an update of the understanding of how the RAS controls nephrogenesis and nephrovascular development. In addition, the investigations linking the perinatal development of RAS inhibition-induced renal dysmorphology and establishment of adult blood pressure are discussed.

Angiotensin II↗
PubMed2006

[Neurotrophin and erectile dysfunction in diabetes].

Neurotrophins play significant roles in the development, differentiation and regeneration of many neurons. The abnormal changes of neurotrophins are one of the nosogenesis of diabetic peripheral neuropathy. Erectile dysfunction (ED) in diabetes is multifactorial and one of the most important causes is the injury of pelvic splanchnic nerves. Neurotrophins therapy shows exact effects on ED with pelvic splanchnic nerves injured. Recent researches indicates that the same treatment has the similar therapeutic effects on the ED animals with diabetes. Neurotrophins therapy develops a new way for us to cure the ED with diabetes.

Animals↗
PubMed2006

[GC-MS analysis of volatile oil from the ear of Schizonepeta tenifolia Briq].

Volatile oil was extracted from the ear of Schizonepeta tenifollia Briq. by supercritical carbon dioxide extraction and steam distillation, then GC-MS was used to analyse their components and determine the content. There were 41 components identified from products of supercritical carbon dioxide extraction, while 32 from those of steam distillation. The content of the main component, pulegone, was also different in the two extracts. It showed that the two extractions have differences in component and content to a certain extent.

Chromatography, Supercritical Fluid↗
PubMed2006

[Study on short-term therapeutic effect and its impact factors of stereotactic surgery for treating opiate users with opiate dependence in Sichuan].

OBJECTIVE: To investigate the common characteristics of the patients, relapse reasons of patients before and after surgery, evaluate the relapse rate and its impact factors, and therapeutic effect of patients accepted stereotactic surgery to treat opiate dependence in Sichuan. METHODS: An investigation, using uniform questionnaires by face-to-face and telephone interview, and gaining data from medical records of patients, was conducted in Mar to Jun 2005, in Sichuan Province. 208 patients (total 212 patients participated in surgery) were invited to gather information about their common characteristics, drug-taking history and the surgery. Statistical methods including t-test, chi2 test and logistic regression were used to analyze the data. RESULTS: (1) 181 male patients and 27 female patients participated in this study, and their mean age was (29.5 +/- 5.5) years. Most of the respondents were in Sichuan and some peripheral province, graduated from senior high school and over, and with various occupations. (2) All patients abused opiate before the surgery, and the average duration of drug-taking was (7.6 +/- 3.4) years. All patients were detoxified by unconstraint or compulsory abstinence before surgery, with mean drug abstinence of 13.9, but relapse occurred after each detoxification. (3) Suffering with no drugs and abstinence syndrome were the two main reasons of relapse before surgery. Compared with relapse before surgery, validating the effect of the surgery treating drug dependence and temptation by drug surroundings were the two main reasons of relapse after surgery. (4) The complication rate was 38.0% (79/208), no severe complications occurred in patients, and most of the complications disappeared or were healed before they were discharged from hospital. Relapse rate within 7 months after surgery was 22.1% (46/208). A significant decrease of relapse time, relapse dose, subjective feel on drugs and relapse euphoria appeared in patients who relapsed after surgery when compared with those before surgery. The univariate and multivariate analysis shows potential significant predictors of relapse rate after surgery to include education (OR = 3.259), operative time (OR = 2.451), social support (OR = 23.256) and doing simple work (OR = 3.328). CONCLUSION: This investigation showed that the stereotactic surgery can eliminate psychological desire for drugs and abstinence syndrome among most of the patients. Satisfactorily short-term therapeutic effect and substantial decline in relapse rate as well as no severe complications were appeared in these patients. Relapse was greatly associated with education, operative time, neuropsychological factors, and social conditions of patients. Therefore, patients' family and the society should strengthen their care, comprehension as well as support, and create better living and working surroundings to facilitate the complete drug abstinence to occur in patients. average duration of drug-taking was (7.6 +/- 3.4) years. All patients were detoxified by unconstraint or compulsory abstinence before surgery, with mean drug abstinence of 13.9, but relapse occurred after each detoxification. (3) Suffering with no drugs and abstinence syndrome were the two main reasons of relapse before surgery. Compared with relapse before surgery, validating the effect of the surgery treating drug dependence and temptation by drug surroundings were the two main reasons of relapse after surgery. (4) The complication rate was 38.0% (79/208), no severe complications occurred in patients, and most of the complications disappeared or were healed before they were discharged from hospital. Relapse rate within 7 months after surgery was 22.1% (46/208). A significant decrease of relapse time, relapse dose, subjective feel on drugs and relapse euphoria appeared in patients who relapsed after surgery when compared with those before surgery. The univariate and multivariate analysis shows potential significant predictors of relapse rate after surgery to include education (OR = 3.259), operative time (OR = 2.451), social support (OR = 23.256) and doing simple work (OR = 3.328). CONCLUSION: This investigation showed that the stereotactic surgery can eliminate psychological desire for drugs and abstinence syndrome among most of the patients. Satisfactorily short-term therapeutic effect and substantial decline in relapse rate as well as no severe complications were appeared in these patients. Relapse was greatly associated with education, operative time, neuropsycological factors, and social conditions of patients. Therefore, patients' family and the society should strengthen their care, comprehension as well as support, and create better living and working surroundings to facilitate the complete drug abstinence to occur in patients.

Adolescent↗
PubMed2006

[Chemical constituents from roots of Platycodon grandiflorum].

OBJECTIVE: To study the chemical constituents from roots of Platycodon grandiflorum. METHOD: Column chromatography (silica gel, macroporous resin, sephadex LH - 20 and the preparative RP - HPLC were used to isolate the constituents. Their structures were elucidated by physical and spectral data. RESULT: Eight compounds were isolated and identified as tangeritin (1), 3-O-beta-D-glucopyranosylplatycodigenin methyl ester (2), 3-O-beta-D-glucopyranosylplaticogenic acid A lactone (3), 3-O-beta-D-glucopyranosylplatycodigenin (4), deapio-platyconic acid A lactone (5), deapio-platycodin-D (6), platycoside-G1 (7) and platycoside-E (8). CONCLUSION: Compounds 1,3 and 5 were isolated from this plant for the first time.

Flavones↗
PubMed2006

[Progress of gene therapy for erectile dysfunction].

Gene therapy is currently investigated in animal studies for treating erectile dysfunction (ED), and is affording an conspicuous therapeutic possibility for the treatment of ED, especially in L-arg-NO-cGMP pathway, ion channel, the protection of nerves and endothelia in erectile tissues. However there still exist so many problems for gene therapy to be effectively applied to the clinical treatment of ED. This review aims to examine the experimental efforts in recent years and tries to give a brief introduction to the new approaches in the field of ED researches.

Animals↗
PubMed2005

The regulator of G-protein signaling proteins involved in sugar and abscisic acid signaling in Arabidopsis seed germination.

The regulator of G-protein signaling (RGS) proteins, recently identified in Arabidopsis (Arabidopsis thaliana; named as AtRGS1), has a predicted seven-transmembrane structure as well as an RGS box with GTPase-accelerating activity and thus desensitizes the G-protein-mediated signaling. The roles of AtRGS1 proteins in Arabidopsis seed germination and their possible interactions with sugars and abscisic acid (ABA) were investigated in this study. Using seeds that carry a null mutation in the genes encoding RGS protein (AtRGS1) and the alpha-subunit (AtGPA1) of the G protein in Arabidopsis (named rgs1-2 and gpa1-3, respectively), our genetic evidence proved the involvement of the AtRGS1 protein in the modulation of seed germination. In contrast to wild-type Columbia-0 and gpa1-3, stratification was found not to be required and the after-ripening process had no effect on the rgs1-2 seed germination. In addition, rgs1-2 seed germination was insensitive to glucose (Glc) and sucrose. The insensitivities of rgs1-2 to Glc and sucrose were not due to a possible osmotic stress because the germination of rgs1-2 mutant seeds showed the same response as those of gpa1-3 mutants and wild type when treated with the same concentrations of mannitol and sorbitol. The gpa1-3 seed germination was hypersensitive while rgs1-2 was less sensitive to exogenous ABA. The different responses to ABA largely diminished and the inhibitory effects on seed germination by exogenous ABA and Glc were markedly alleviated when endogenous ABA biosynthesis was inhibited. Hypersensitive responses of seed germination to both Glc and ABA were also observed in the overexpressor of AtRGS1. Analysis of the active endogenous ABA levels and the expression of NCED3 and ABA2 genes showed that Glc significantly stimulated the ABA biosynthesis and increased the expression of NCED3 and ABA2 genes in germinating Columbia seeds, but not in rgs1-2 mutant seeds. These data suggest that AtRGS1 proteins are involved in the regulation of seed germination. The hyposensitivity of rgs1-2 mutant seed germination to Glc might be the result of the impairment of ABA biosynthesis during seed germination.

Abscisic Acid↗
PubMed2005

Tubular mitochondrial alterations in neonatal rats subjected to RAS inhibition.

Pharmacological interruption of the angiotensin II (ANG II) type 1 receptor signaling during nephrogenesis in rats perturbs renal tubular development. This study aimed to further investigate tubular developmental defects in neonatal rats subjected to ANG II inhibition with enalapril. We evaluated tubular ultrastructural changes using electron microscopy and estimated spectrophotometrically activity or concentrations of succinate dehydrogenase (SDH), cytochromes a and c, which are components of mitochondrial respiratory chain, on postnatal days 2 and 9 (PD2 and PD9). Renal expression of sodium-potassium adenosinetriphosphatase (Na(+)-K(+)-ATPase) and two reflectors of mitochondrial biogenesis [mitochondrial transcription factor A (TFAM) and translocase of outer mitochondrial membrane 20 (TOM20)] also were studied using Western immunoblotting and immunohistochemistry. Enalapril disrupted inner mitochondrial membranes of developing cortical and medullary tubular cells on PD2 and PD9. These findings were paralleled by impaired mitochondrial respiratory function, as revealed from the changes in components of the mitochondrial respiratory chain, such as decreased cytochrome c level in the cortex and medulla on PD2 and PD9, decreased cytochrome a level in the cortex and medulla on PD2, and diminished cortical SDH activity on PD2 and PD9. Moreover, tubular expression of the most active energy-consuming pump Na(+)-K(+)-ATPase was decreased by enalapril treatment. Renal expression of TFAM and TOM20 was not altered by neonatal enalapril treatment. Because nephrogenesis is a highly energy-demanding biological process, with the energy being utilized for renal growth and transport activities, the structural-functional alterations of the mitochondria induced by neonatal enalapril treatment may provide the propensity for the tubular developmental defect.

Angiotensin II↗