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Biomedical subjects

Xiao-Dong Liu

Publications and source records attributed to Xiao-Dong Liu.

At least 19 recordsLinked to original sources
PubMed2006

Simple, sensitive and rapid liquid chromatography/atmospheric pressure chemical ionization mass spectrometric method for the quantitation of Ranolazine in rat plasma.

A sensitive and specific method using liquid chromatography with atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS) has been developed and validated for the identification and quantification of Ranolazine in rat plasma. A simple liquid-liquid extraction procedure was followed by injection of the extracts onto a C18 column with isocratic elution and detection using a single quadrupole mass spectrometer in selected ion monitoring (SIM) mode. The method was tested using six different batches of blank plasma. Linearity was established for the concentration range 0.02-10.0 microg/mL, with a coefficient of determination (r) of 0.9998 and good back-calculated accuracy and precision. The intra- and inter-day precision (relative standard deviation (RSD) %) was lower than 10%, and accuracy ranged from 85 to 115%. The lower limit of quantification was reproducible at 0.01 microg/mL with 20 microL plasma. The proposed method enables the unambiguous identification and quantification of Ranolazine for pre-clinical and clinical studies.

Acetanilides↗
PubMed2005

Simple, sensitive and rapid LC-ESI-MS method for the quantitation of lafutidine in human plasma--application to pharmacokinetic studies.

A sensitive and specific liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed and validated for the identification and quantification of lafutidine in human plasma. Lafutidine and internal standard were isolated from plasma samples by liquid-liquid extraction with diethyl ether. The chromatographic separation was accomplished on a stainless-steel column (C18 Shim-pack 5 microm 150 mm x 2.0 mm i.d. Shimadzu) at a flow rate of 0.2 ml/min by a gradient elution. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via electrospray ionization (ESI) source. The method was proved to be sensitive and specific by testing six different plasma batches. Linearity was established for the range of concentrations 1.0-400.0 ng/ml with a coefficient of determination (r) of 0.9998 and good back-calculated accuracy and precision. The intra- and inter-day precision (R.S.D.%) was lower than 10% and accuracy ranged from 85 to 115%. The lower limit of quantification was identifiable and reproducible at 0.5 ng/ml with 0.2 ml plasma. The proposed method enables the unambiguous identification and quantification of lafutidine for pharmacokinetic, bioavailability or bioequivalence studies.

Acetamides↗
PubMed2005

Determination of limonin in rat plasma by liquid chromatography-electrospray mass spectrometry.

A simple, sensitive and selective liquid chromatography coupled with electrospray ionization mass spectrometry (LC/ESI/MS) method for determination of limonin (LM) in rat plasma has been developed and validated. The method had advantages of a single liquid-liquid extraction with ether and high sensitivity. Analyses were conducted at a flow rate of 0.2 ml/min by a gradient elution. The detection utilized selected ion monitoring in the negative ion mode at m/z 460.00 and 423.15 for the deprotonated molecular ions of LM and the internal standard, respectively. The quantitation limit for LM in rat plasma was 1.0 ng/ml. The linearity was also excellent over the concentration range of 1.9-500 ng/ml of LM. The intra- and inter-day precision (relative standard deviation (R.S.D.%)) was lower than 10% and accuracy ranged from 90 to 110%, showing a good reproducibility. This developed method was successfully applied to analysis of LM in biological fluids.

Animals↗
PubMed2005

A national probability survey of American Medical Association gynecologists and primary care physicians concerning menopause.

OBJECTIVE: This survey intended to clarify physicians' understanding of the issues surrounding women, menopause, alternative medicine, and drug therapy for the treatment of menopause. STUDY DESIGN: This study was designed as a national probability sample survey of primary care physicians and gynecologists nationwide. Its focus was to identify major concerns and issues identified by patients about menopause and perceived communication with effectiveness how to communicate with their patients. Physicians were also asked to rate their comfort level in recommending the use of herbal remedies and which herbal remedy they felt comfortable recommending to interested patients. RESULTS: Data indicated that a patient's complaint about menopausal symptoms was the most common factor leading to discussion of menopausal issues with physicians (91%) and that the primary concern to the patient was management of menopausal symptoms. Other factors were controversies about hormone replacement therapy, long-term health implications of menopause, and hormone replacement therapy. Eighty percent of the physician found confusing messages with regard to menopause to be the most challenging aspect in patient communication. The second most challenging issue is "inconclusive data about hormone replacement therapy" (56%). Seventy-six percent of the physicians found "showing sympathy" to be the most important factor for the physicians to communicate effectively with patients, whereas "being honest and open" was the most important patient attitude cited for the same purpose. When it comes to herbal therapy for menopause symptom control, only 4% of the physicians indicated that none of their patients take any remedies. Only 18% were not very comfortable in discussing or recommending herbal therapies, whereas the rest ranged from fairly comfortable to completely comfortable. CONCLUSION: This study has provided data with regard to physician understanding of menopause treatment options and their primary interaction with patients on this issue. More in-depth studies concerning efficacy and/or side effects of each available treatment will be the relevant next step, given the controversies about both hormone replacement therapy and alternative therapies. The relative efficacy, safety, and cost-effectiveness of different treatments should also be put into the context of both clinical diagnosis and physicians' clinical judgment. Attention to comments by physicians and patients with regard to communication may produce better information exchange and trust between patient and physician.

Attitude of Health Personnel↗
PubMed2005

[Treatment effect of percutaneous vertebroplasty combined with interventional chemotherapy on vertebral metastases].

BACKGROUND & OBJECTIVE: Vertebral metastasis is a common manifestation of patients with advanced cancer without effective treatment. This study was to explore treatment value and efficacy of percutaneous vertebroplasty (PVP) combined with interventional chemotherapy on vertebral metastases. METHODS: Seventy-five patients with vertebral metastases (42 men, 33 women; aged 31-76 years) were divided into 2 groups: 39 were treated by PVP combined with chemotherapy (VPCC group), and 36 were treated by PVP alone (VP group). All procedures were guided by CT scan. The results and complications were evaluated by pain questionnaire and routine follow-up. RESULTS: Response rate was significantly higher in VPCC group than in VP group (93.0% vs. 74.4%, P < 0.05); complete response rates of VPCC group and VP group were 25.6% and 10.3%. Common complication of VPCC was transient aggravation of pain. CONCLUSIONS: PVP may release the pain, and consolidate the vertebrae of patients with vertebral metastases. Its short-term effect may be enhanced by adding drugs into bone cement.

Adult↗
PubMed2005

Preliminary studies on nitrous oxide emissions from the ornithogenic soils on Xi-sha atoll, South China Sea.

The preliminary measurements of nitrous oxide fluxes from the ornithogenic soils on tropical Xi-sha atoll were made using a closed chamber technique for the first time. N2O fluxes from the ornithogenic soils ranged from 1.8 to 40.3 microg/(m2 x h) on Dong Island and 3.2 to 20.4 microg/(m2 x h) on Yongxing Island and their flux averaged 11.0 microg/(m2 x h) and 8.3 microg/(m2 x h), respectively. N2O fluxes from two wetland sites in salt marsh of Dong Island were approximately one order of magnitude lower than those from the ornithogenic soils and averaged 2.1 microg/(m2 x h) and 2.4 microg/(m2 x h). The diurnal variation cycle in the fluxes was obtained at the observation sites; the N2O flux increased with the increase in soil temperature. The sudden increase in soil moisture greatly stimulated N2O emission from the ornithogenic soils on Dong Island due to the heavy rainfall. The undisturbed soils showed the lower N2O fluxes and the average was 4.8 microg/(m2 x h) and the soils via the reclamation showed the higher N2O fluxes and the average was 16.6 microg/(m2 x h) on Yongxing Island, suggesting that the changes of land use have an important effect on N2O fluxes from the ornithogenic soils. In addition, the N2O fluxes at the different sites showed high spatial variations. The fluxes were positively correlated with the concentrations of NO3-, PO4(3-) and Mn in the soils. The negative correlation between the fluxes and total S concentration in the ornithogenic soils was also found for the first time. Coastal soils or sediments constitute an important source of global atmospheric N2O and the increases in nitrogen loading from seabird guanos will lead to significant increases in the flux of this atmospherically active gas.

Nitrous Oxide↗
PubMed2005

Molecular evidence of barley yellow dwarf virus replication/movement suppressed by the resistance gene Bdv2.

A wheat-Thinopyrum intermedium translocation line YW642 possesses the resistance to GAV serotype of barley yellow dwarf virus (BYDV), in which the resistance gene Bdv2 is derived from the chromosome 7X of Thinopyrum intermedium group 7. It is interesting to analyze BYDV accumulation content in the resistant and susceptible wheat plants for controlling BYDV disease and understanding the resistance mechanism against BYDV. In the paper, semi-quantitative reverse-transcription PCR (RT-PCR) was used to detect and quantify BYDV-GAV in the resistant and susceptible plants using specific primers for the coat protein (CP) and RNA-dependent RNA polymerase (RdRp) genes of BYDV-GAV serotype. On the inoculation site, the amount of the virus in the resistant wheat line (YW642) was much lower compared to the susceptible sib line (YW641). There was small amount of the virus could be detected in YW642 at 2-5 days post infestation (dpi), afterwards the amount of virus decreased and no virus could be detected at 14 and 16 dpi. In the uninoculated upper leaves, no BYDV was detected in YW642 from 1 to 14 dpi, while the virus could be detected at 3 dpi and then accumulated rapidly in YW641. These results showed at molecular level that the replication and/or movement of BYDV-GAV were strongly suppressed in YW642, presumably owing to the action of the BdV2 gene.

Chromosome Mapping↗
PubMed2004

Theoretical studies of ground and excited electronic States in a series of rhenium(i) bipyridine complexes containing diarylethynyl-based structure.

The photophysical properties, which vary as X is varied, of Re(I)-halide complexes (X2-bpy)ReICl(CO)3 (where X=ph, DAE, DNE, and DPE; ph = phenyl (1); DAE = di(amineoethynylbenzene) (2); DPE = di(phenylethynylbenzene) (3); DNE = di(nitroethynylbenzene) (4); bpy=2,2'bipyridine), are investigated using density functional theory (DFT). The electronic properties of the neutral molecules, in addition to the positive and negative ions, are studied using B3LYP functional. Excited singlet and triplet states are examined using time-dependent density functional theory (TDDFT). The low-lying excited-state geometries are optimized at the ab initio configuration interaction singlets level. As shown, the diarylethynyl-based structure is an integral component of the bpy pi-conjugated network, which results in a good planar structure. The occupied orbitals involved in the transitions have a significant mixture of metal Re and group Cl, and the lowest unoccupied orbital is a pi orbital, which extends from ligand bpy to diarylethynyl-based substituents. The luminescence for each complex originates from the lowest triplet excited states and is assigned to the mixing of MLCT and LLCT characters. Significant insights on the effects of these diarylethynyl conjugated structure and ending substituents (NH2, ph, and NO2) on absorption and emission spectra are observed by analysis of the results of the TDDFT method. The diarylethynyl-based pi-conjugated network makes both the absorption and emission spectra red-shifted compared with simple complex (bpy)ReICl(CO)3. Furthermore, an electron-releasing group (NH2) makes absorption and emission spectra blue-shift and an electron-withdrawing group (NO2) makes them red-shift.

Journal Article↗
PubMed2004

Effects of tetraethylammonium on Kx channels and simulated light response in rod photoreceptors.

Rod photoreceptors express a unique type of noninactivating potassium channels, Kx channels, which play an important role in setting the dark potential and participate in shaping the light response. Biophysical studies of Kx channels are limited. For example, the effects of a conventional blocker of potassium channels, tetraethylammonium (TEA), on Kx channels have not been extensively studied. Here we demonstrate that TEA blocks Kx channels, one molecule of TEA being sufficient to block the channel. Half of the Kx current was inhibited at K0.5 = 5.6 mM. The TEA-induced block of Kx channels depended on extracellular potassium: the higher the potassium concentration, the stronger the block. Using TEA, we blocked potassium channels to reveal their role in shaping the simulated light response (SLR) of rods. We showed that TEA slowed down SLR and sometimes caused generation of action potentials. We developed a complete computer model of the rod, which accurately reproduced the main features of the light response and allowed us to demonstrate that it was suppression of Kx channels that was essential for slowing SLR and increasing excitability of rods. The results reported in this work further establish the importance of Kx channels in rod photoreceptor function.

Animals↗
PubMed2004

Radiation-induced bystander effect in immune response.

OBJECTIVE: Since most reports on bystander effect have been only concerned with radiation-induced damage, the present paper aimed at disclosing whether low dose radiation could induce a stimulatory or beneficial bystander effect. METHODS: A co-culture system containing irradiated antigen presenting cells (J774A.1) and unirradiated T lymphocytes (EL-4) was established to observe the effect of J774A.1 cells exposed to both low and high doses of X-rays on the unirradiated EL-4 cells. Incorporation of 3H-TdR was used to assess the proliferation of the EL-4 cells, expression of CD80/86 and CD48 on J774A.1 cells was measured with immunohistochemistry and flow cytometry, respectively. NO release from J774A.1 cells was estimated with nitrate reduction method. RESULTS: Low dose-irradiated J774A.1 cells could stimulate the proliferation of the unirradiated EL-4 cells while the high dose-irradiated J774A.1 cells exerted an inhibitory effect on the proliferation of the unirradiated EL-4 cells. Preliminary mechanistic studies illustrated that the differential changes in CD48 expression and NO production by the irradiated J774A.1 cells after high and low dose radiation might be important factors underlying the differential bystander effect elicited by different doses of radiation. CONCLUSION: Stimulatory bystander effect can be induced in immune cells by low dose radiation.

Animals↗
PubMed2004

[A preliminary report on treatment of myelodysplastic syndrome with cyclosporin a and androgen].

The study was aimed to explore clinical result of cyclosporin A (CsA) and androgens for treatment of myelodysplastic syndrome (MDS) with refractory anemia. Four cases of MDS-RA were treated with CsA and androgens, while the changes of blood counts, bone marrow and chromosome were observed. The results showed that substantial hematological response was observed in all four patients, that their anemia improved and all transfusion-dependent patients achieved transfusion independence. In conclusion, CsA and Adr therapy was well tolerated. CsA and Adr therapy offer an alternative treatment of MDS with RA. The mechanisms of the benifical effect from this therapy remain the subject of an ongoing study.

Adolescent↗
PubMed2003

Conservative form of the density of states of a photonic crystal with a pseudogap.

We show that the total number of states in a photonic crystal in the entire allowed frequency regime will be conserved, and it is equal to that of its corresponding effective medium, i.e., if the density of states (DOS) has a valley(s) in some range(s) of frequencies, it must be compensated for by increases over some other range(s). This rule is of importance in developing a model pseudogap in order to describe the mean emission characteristics of the system when there is a collection of dependently emitting atoms or molecules with essentially random dipole orientations in a large volume and the spectrum of the active atoms is wide enough. This is because, with this rule, the states-conservative model always results in DOS-induced suppression, absolute enhancement, narrowing, spectrum splits, and redshift or blueshift of spontaneous-emission spectra.

Journal Article↗
PubMed2003

Effects of 0.075 Gy x-ray irradiation on the expression of IL-10 and IL-12 in mice.

The objective was to observe the effects of 0.075 Gy low dose radiation (LDR) on the synthesis of IL-10 in splenocytes and the secretion of IL-12 by peritoneal macrophages. Kunming mice were selected and randomly grouped. Northern blot and flow cytometry were adopted to detect the changes of IL-10 at mRNA and protein levels, respectively. Northern blot and ELISA were used, respectively, to examine the changes of IL-12 p35/p40 mRNA and IL-12 p70 protein levels. IL-10 mRNA decreased significantly in splenocytes, while both IL-12 p35 and p40 subunit mRNA levels in macrophages increased after whole body irradiation (WBI) with 0.075 Gy x-rays. Meanwhile, IL-10 synthesis in splenocytes decreased beginning from 4 h after exposure and remaining at a lower level up to 48 h, and IL-12 secretion by macrophages was found to take the opposite direction, i.e. increase significantly. In conclusion, WBI with 0.075 Gy x-rays may suppress IL-10 both at the mRNA level and protein level and stimulate IL-12 expression simultaneously, which might contribute to a shift of the immune response in favour of Th1 differentiation.

Animals↗
PubMed2003

Application of Molecular Adsorbents Recirculating System to remove NO and cytokines in severe liver failure patients with multiple organ dysfunction syndrome.

BACKGROUND: Molecular Adsorbents Recirculating System (MARS) is a new promising artificial liver support therapy, the aim of this study was to assess the effectiveness of MARS to remove nitrous oxide (NO) and cytokines in severe liver failure patients with multiple organ dysfunction syndrome (MODS). METHODS: Sixty single MARS treatments were performed with length of 6-24 h on 24 severe liver failure patients (18 males/6 females) with MODS. RESULTS: The MARS therapy was associated with a significant removal of NO and certain cytokines such as TNF-alpha, IL-6, IL-8, and INF-gamma, together with marked reduction of other non-water-soluble albumin bound toxins and water-soluble toxins, these were associated with a improvement of the patients' clinical conditions including hepatic encephalopathy, deranged hemodynamic situation and as well as renal and respiratory function, thus resulted into marked decrease of Sequential Organ Failure Assessment (SOFA) score and improved outcome: nine patients were able to be discharged from the hospital or bridged to successful liver transplantation, the overall survival of 24 patients was 37.5%. CONCLUSION: We can confirm the positive therapeutic impact and safety to use MARS on liver failure patients with MODS associated with elevated levels of NO and cytokines.

Adolescent↗
PubMed2003

The antihyperglycaemic activity of berberine arises from a decrease of glucose absorption.

The mechanism of action of berberine as an antihyperglycaemic agent was investigated in the Caco-2 cell line. Berberine was found to effectively inhibit the activity of disaccharidases in Caco-2 cells. It also decreased sucrase activity after preincubation with Caco-2 cells for 72 hours. However gluconeogenesis and glucose consumption of Caco-2 cells were not influenced. 2-Deoxyglucose transporting through Caco-2 cell monolayers was decreased by berberine but the effect was not statistically significant. These results suggest that the antihyperglycaemic activity of berberine is at least partly due to its ability to inhibit alpha-glucosidase and decrease glucose transport through the intestinal epithelium.

Berberine↗
PubMed2003

Studies on specific interaction of beta-2-glycoprotein I with HBsAg.

AIM: To observe the binding activity of beta-2-glycoprotein I(beta(2)GPI) to hepatitis B surface antigen (HBsAg) and the possible roles of beta(2)GPI in hepatitis B virus (HBV) infection. METHODS: The rationale of ELISA methods and ELISA-based research method and ligand-blotting technique were used to detect the specific interaction of beta(2)GPI with HBsAg. RESULTS: With the increase of rHBsAg, the binding of beta(2)GPI to rHBsAg elevated, and these changes had statistic significance. When we added non- biotinlyated beta(2)GPI, the OD value significantly decreased though they still were positively relevant to rHBsAg, suggesting non- biotinlyated beta(2)GPI competed with biotinlyated beta(2)GPI to saturate the binding sites on rHBsAg. Meanwhile BSA was used as negative control to substitute for rHBsAg coating the plates. The results indicated no interaction between beta(2)GPI and BSA, suggesting the affinity of beta(2)GPI to rHBsAg was specific. The ligand blotling indicated that beta(2)GPI might bind to rHBsAg no matter whether it was under reduced condition or not. CONCLUSION: The binding of beta(2)GPI to HBsAg suggests that beta(2)GPI may be a carrier of HBV and that beta(2)GPI may play important roles in HBV infection.

Binding Sites↗