Biomedical subjects

Yu Dong

Publications and source records attributed to Yu Dong.

At least 19 recordsLinked to original sources

PubMed2006

[Linear scanning analysis of prehistoric human bones in Xigongqiao Site, Tengzhou, Shandong Province by use of SEM-EDS].

Ancient human bones in Xigongqiao Site, Tengzhou, Shandong Province, were analyzed by use of SEM-EDS. SEM indicated that the microstructure of Haversian system was destroyed under the impact of bone diagenesis. The apparent difference in elemental distribution in the bone cross section showed that the enrichment or loss of elements can occur not only in the inner and outer surface, but also in the middle. This study will have great influence on how to deal with the ancient human bones before any palaeodietary research in the future.

Animals↗

PubMed2006

[Studies on chemical constituents in spikes of Schizonepeta tenuifolia].

OBJECTIVE: To study the chemical constituents in the spikes of Schizonepeta tenuifolia. METHOD: Compounds were isolated and purified with silica gel, ODS and Sephadex LH-20 gel column chromatography, and their structures were determined by using spectroscopic analysis including MS and NMR. RESULT: Nine compounds were isolated and identified as 5, 7-dihydroxy-6, 4'-dimethoxyflavone (1), 5, 7-dihydroxy-6, 3', 4'-trimethoxyflavone (2), ursolic acid (3), 3-hydroxy-4(8)-ene-p-menthane-3(9)-lactone (4), 5, 7, 4'-trihydroxyflavone (5), 5, 4'-dihydroxy-7-methoxyflavone (6), hesperidin (7), luteolin (8) and daucesterol (9). CONCLUSION: Compounds 1, 2, 6 were first obtained from the spikes of S. tenuifolia.

Flavones↗

PubMed2005

Identification and quantitative determination of benproperine metabolites in human plasma and urine by liquid chromatography-tandem mass spectrometry.

Two novel metabolites of benproperine (BPP), 1-[1-methyl-2-[2-(phenylmethyl)phenoxy]ethyl]-3-piperidinol (3-OH-BPP) and 1-[1-methyl-2-[2-(phenylmethyl)phenoxy]ethyl]-4-piperidinol (4-OH-BPP), were confirmed by comparison of retention times and mass spectra with those of synthetic standards using liquid chromatography-tandem mass spectrometry. Selective and sensitive procedures were developed for the simultaneous determination of BPP, 3-OH-BPP and 4-OH-BPP in human plasma and urine. The analytes were extracted from plasma sample and enzymatically hydrolyzed urine samples by liquid-liquid extraction, separated through a Diamonsil C(18) column (150 mm x 4.6 mm i.d.) and determined by tandem mass spectrometry with an electrospray ionization interface in selected reaction monitoring mode. Dextromethorphan was used as internal standard. The mobile phase consisted of acetonitrile-water-formic acid (34:66:1, v/v/v), and flow-rate was 0.5 ml min(-1). This method has a lower limit of quantification (LLOQ) of 60, 4.0 and 4.0 nmol l(-1)for BPP, 3-OH-BPP and 4-OH-BPP in plasma, 4.9, 4.7 and 2.4 nmol l(-1) in urine, respectively. The intra- and inter-run precision were measured to be below 9.2%, and the accuracy was within +/-4.3% for the analytes. The method was successfully used to determine BPP, 3-OH-BPP and 4-OH-BPP in plasma and urine for pharmacokinetic investigation. The results indicated residue of 3-OH-BPP in the body at least 192 h after an oral dose of BPP.

Antitussive Agents↗

PubMed2005

Phase behaviors of AOT/longer chain n-alkanes reverse micelles in the presence of compressed ethylene.

It was found that, in a suitable pressure range, ethylene could increase the amount of solubilized water in reverse micelles of sodium bis-2-ethylhexylsulfosuccinate (AOT) in longer chain n-alkanes considerably, where the phase separation was induced by a micelle-micelle interaction mechanism. The microenvironments in the ethylene-stabilized reverse micelles were investigated by the UV-vis adsorption spectra using methyl orange (MO) as a probe. The maximum absorption of MO decreased with the increase of ethylene pressure at constant W0 value. Conductivity measurements demonstrated that the percolation temperature of the reverse micellar system increased considerably after compressed ethylene was added. The results of this work confirm that some small-molecule gases have the function of cosurfactants to stabilize reverse micelles.

Journal Article↗

PubMed2005

Transplantation of human limbal cells cultivated on amniotic membrane for reconstruction of rat corneal epithelium after alkaline burn.

BACKGROUND: The transplantation of limbal epithelial cells cultivated on amniotic membrane is a newly developed treatment for limbal stem cell deficiency. The purpose of our study was to investigate the biological characteristics of limbal epithelial cells and evaluate the effect of transplantation of cultivated human limbal epithelial cells on ocular surface reconstruction in limbal stem cell deficiency rat model. METHODS: Human limbal cells were isolated and cultivated in vitro. Cytokeratins 3, 12, and 19 (K3, K12 and K19) and p63 were detected by immunofluorescent staining or RT-PCR. BrdU labelling test was used to identify the slow cycling cells in the cultures. Limbal stem cell deficiency was established in rat cornea by alkali burn. Two weeks after injury, the rats received transplants of human limbal stem cells cultivated on amniotic membrane carrier. The therapeutic effect was evaluated by slit lamp observation, Hemotoxin and Eosin (HE) staining and immunofluorescent staining. RESULTS: On day 7 in primary culture, p63 and K19 were strongly expressed by most cells but only a few cells expressed K3. On days 14 and 21, p63 and K19 were still expressed by a majority of cells, but the expressive intensity of p63 decreased in a number of cells, while the proportion of K3 positive cells increased slightly and some cells coexpressed p63 and K3. RT-PCR showed that gene expression of both p63 and K12 were positive in cultivated limbal cells, but in mature superficial epithelial cells, only K12 was detected. BrdU labelling test showed that most cells were labelled with BrdU after 7 days' labelling and BrdU label retaining cells were observed after chasing for 21 days with BrdU free medium. For in vivo test, slit lamp observation, HE staining and immunofluorescent staining showed that the rats receiving transplant of human limbal stem cells cultivated on amniotic membrane grew reconstructed corneas with intact epithelium, improved transparency and slight or no neovascularization. A majority of epithelial cells of the reconstructed cornea were positive to antihuman nuclear antibody and cells expressing K3 were found mainly in superfacial epithelium. CONCLUSIONS: Limbal stem cells can be cultivated in vitro: the cells are characterized by high proliferation and slow cycling and identified as p63/K19 positive and K3/K12 negative. During culture, some stem cells can proliferate and differentiate into mature cornea epithelial cells. Amniotic membrane is a suitable carrier for limbal stem cells. Transplantation of human limbal stem cells cultivated on amniotic membrane can functionally reconstruct rat cornea with limbal stem cell deficiency.

Amnion↗

PubMed2005

Compressed CO2 in AOT reverse micellar solution: effect on stability, percolation, and size.

The effects of compressed CO(2) in sodium bis-2-ethylhexylsulfosuccinate (AOT)/decane reversed micellar solution on the stability of the micelles, interface, and micelle/micelle interactions were studied. It was demonstrated that the compressed gas could increase the solubilization of water in this system. The formation of the stabilized one-phase microemulsion was confirmed by conductivity measurements. A shift in percolation threshold to higher temperature was observed after compressed gas was added. The gyration radius (R(g)) of the reverse micelles was determined using SAXS. R(g) increases with the addition of water, while it decreases appreciably with increasing pressure of compressed gas at fixed W(0). These results were interpreted in terms of an increase of the rigidity of the interface layer and a decrease of the interdroplet attraction. The results of this work provide useful information to get insight into the mechanism of cosurfactants to stabilize reverse micelles.

Journal Article↗

PubMed2005

Enhanced stabilization of reverse micelles by compressed CO2.

The effect of compressed CO2 on the solubilization capacity of water in reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in longer chain n-alkanes was studied at different temperatures and pressures. It was found that the amount of solubilized water is increased considerably by CO2 in a suitable pressure range. The suitable CO2 pressure range in which the solubilization capacity of water could be enhanced decreased with increasing W0 (water-to-AOT molar ratio). The microenvironments in the CO2-stabilized reverse micelles were investigated by UV/Vis adsorption spectroscopy with methyl orange (MO) as probe. The mechanism by which the reverse micelles are stabilized by CO2 is discussed in detail. The main reason is likely to be that CO2 has a much smaller molecular volume than the n-alkane solvents studied in this work. Therefore, it can penetrate the interfacial film of the reverse micelles and stabilize them by increasing the rigidity of the micellar interface and thus reducing the attractive interaction between the droplets. However, if the CO2 pressure is too high, the solvent strength of the solvents is reduced markedly, and this induces phase separation in the micellar solution.

Journal Article↗

PubMed2005

[Expression of NY-ESO-1 and LAGE-1 cancer-testis antigens in hepatocellular carcinoma].

OBJECTIVE: To study the role of NY-ESO-1 and LAGE-1 cancer-testis antigens as targets for immunotherapy and the relationship between corresponding gene expression and biologic behavior of hepatocellular carcinoma (HCC). METHODS: The expression of NY-ESO-1 and LAGE-1 was studied in frozen tumor tissues from 30 cases of HCC by reverse transcriptase-polymerase chain reaction and immunohistochemistry. NY-ESO-1 expression and its distribution were further studied by immunohistochemistry in a tissue array contained 191 cases of HCC. RESULTS: NY-ESO-1 and LAGE-1 mRNAs were expressed in 33.3% (10/30) and 16.7% (5/30) of HCC respectively. Either NY-ESO-1 or LAGE-1 was expressed in 36.7% (11/30) cases. NY-ESO-1 was expressed mainly in the cytoplasm of tumor cells. It was positive in 13.8% (24/174) cases of HCC. There was an increased expression of NY-ESO-1 from 6.8%, 3/44 in small HCC, 16.2%, 21/130 in advanced HCC and 23.1%, 12/52 in metastatic HCC. The expression in the non-metastatic group was 9.8% (12/122). The differences between the metastatic group and non-metastatic group (< 0.05) and between normal liver tissue and HCC (< 0.01) were statistically significant. There was no relationship between NY-ESO-1 expression and tumor size. NY-ESO-1 and LAGE-1 were not detected in adjacent normal liver tissue. CONCLUSIONS: NY-ESO-1 and LAGE-1 are expressed in a high percentage of HCC, especially in cases with metastasis. It is thus possible that NY-ESO-1/LAGE-1 can serve as targets for antigen-specific immunotherapy in HCC and NY-ESO-1 peptide vaccination may be of use for patients with advanced HCC.

Adult↗

PubMed2005

[Investigation on the hydroxylation metabolism of imrecoxib in vitro by using recombinant human CYPs].

AIM: To identify the drug-metabolizing enzymes involved in the hydroxylation of the new anti-inflammatory and anodyne imrecoxib. METHODS: Imrecoxib was incubated with heterologous expression human cytochrome P450 (rCYPs) in vitro, and metabolites and remained parent drug were detected with liquid chromatography-multistage mass spectrometry. The contribution of 4 CYPs in the hydroxylation metabolism of imrecoxib was evaluated by total normalized rate (TNR) method. RESULTS: Imrecoxib is metabolized by CYP2C9, CYP2D6 and CYP3A4, with the rate of 62.5%, 21.1% and 16.4%, respectively. CONCLUSION: CYP2C9 is the major enzyme involved in imrecoxib hydroxylation metabolism.

Aryl Hydrocarbon Hydroxylases↗

PubMed2004

Acetylcholine release in the hippocampus during the operant conditioned reflex and the footshock stimulus in rats.

The activity of the septo-hippocampal cholinergic pathway was investigated by measuring changes in the extracellular acetylcholine (ACh) levels in the hippocampus, by means of microdialysis, during the operant conditioned reflex and the repeated footshock stimulus. Microdialysis samplings were conducted in a Skinner box where lights were delivered as conditioned stimuli (CS) paired with footshocks as unconditioned stimuli (US). Two groups of rats were used. Extracellular ACh and choline (Ch) in samples collected at 6min intervals were assessed by high-performance liquid chromatography with electrochemical detection. The elevation of hippocampus ACh was observed in the two experimental groups. The increase in ACh during aversive stimulus (footshock) was significantly larger and was probably related to the number of footshocks. There might be moderate increase in the hippocampal ACh release during the retrieval of information. The concentration of choline showed no significant fluctuation in the two groups during the whole process. This experiment explored in more detail hippocampal cholinergic activity in relation to the two different procedures.

Acetylcholine↗

PubMed2004

Enhancement of the solubilization capacity of water in Triton X-100/cyclohexane/water system by compressed gases.

The effect of compressed CO2 and ethylene on the properties of Triton X-100/cyclohexane/water systems was studied at different temperatures and pressures. Surprisingly, it was discovered that the compressed gases had the functions of co-surfactants. At suitable pressures, the water-to-surfactant molar ratio (W0) was enhanced significantly by the dissolution of the gas in the solution. The microenvironment in the reverse micelles was investigated by UV-visible spectroscopy by using methyl orange (MO) as a probe. The influence of n-hexane, Na2CO3, NaHCO3, H2C2O4, and CaCl2 at various concentrations on the solubilization of water in the absence of compressed gases was also investigated in order to obtain some information about the mechanism of the interesting phenomenon. This new route to stabilize reverse micelles may have potential applications to other similar systems. Moreover, the results of this work provide some useful information to get insight into the mechanism of co-surfactants, because a conventional co-surfactant usually contains both polar group and hydrocarbon chain, and it is very difficult to clarify the functions these two groups, while the gases used in this work are small nonpolar molecules, which solely have the function of the hydrocarbon chain in a co-surfactant.

Journal Article↗

PubMed2004

Novel electrochemical method for sensitive determination of homocysteine with carbon nanotube-based electrodes.

An electrochemical method has been successfully demonstrated for sensitive determination of homocysteine (HcySH) with carbon nanotube (CNT)-modified glassy carbon (GC) electrodes. Cyclic voltammetric results clearly show that carbon nanotubes, especially those pretreated with nitric acid, possess an excellent electrocatalytic activity toward the oxidation of HcySH at a low potential (0.0 V versus Ag/AgCl). The remarkable catalytic property of the acid-pretreated CNTs, which is essentially associated with oxygen-containing moieties introduced on the tube surface, has been further exploited as a sensitive determination scheme for HcySH. Continuous-flow amperometric results suggest that the CNT-based electrodes (p-CNT/Nafion/GC), which were prepared by using Nafion to solubilize and further immobilize CNTs on GC electrodes, show striking analytical properties of good stability and reproducibility and strong ability against electrode fouling. Such analytical properties, along with the low operation potential, substantially enable a reliable and sensitive determination of HcySH with a good dynamic linearity up to 60 microM and a detection limit of 0.06 microM (S/N = 3). The catalytic mechanism and the possible application of the as-prepared p-CNT/Nafion/GC electrodes for the study of the auto-oxidation of HcySH are also demonstrated and discussed.

Biosensing Techniques↗

PubMed2004

Brief seizure activity alters Ca2+/calmodulin dependent protein kinase II dephosphorylation and subcellular distribution in rat brain for several hours.

The effect of a brief pentylenetetrazol (PTZ) convulsive seizure on rat cerebral cortical Ca2+/calmodulin dependent protein kinase II (CaMKII) was investigated. By immunoblot, it was found that a single PTZ seizure, lasting less than a minute, caused translocation of CaMKII alpha-subunit (alpha-CaMKII) from the particulate to the soluble fraction for several hours, paralleled by a dramatic loss of alpha-CaMKII Thr286 phosphorylation. The reduced alpha-CaMKII Thr286 phosphorylation apparently resulted from enhanced phosphatase activity following PTZ seizure, especially in the particulate fraction. CaMKII translocation and phosphatase activation following a brief seizure episode can both contribute to long-lasting CaMKII regulation far outlasting the immediate effects of the seizure on neuronal function.

Animals↗

PubMed2004

Prolonged changes in Ca2+/calmodulin-dependent protein kinase II after a brief pentylenetetrazol seizure; potential role in kindling.

This study evaluated the alteration of CaMKII autophosphorylation and distribution in rat brain following a single, brief pentylenetetrazol (PTZ) seizure and during PTZ kindling. Total CaMKII alpha subunit (alpha-CaMKII) and alpha-CaMKII phosphorylated at Thr(286) were detected by immunoblot. A large decrease in CaMKII Thr(286) phosphorylation, as well as CaMKII translocation from particulate to soluble fraction was observed in both cerebral cortex and hippocampus 0.5-4 h after the brief PTZ convulsion. These changes reverted to control values by 12 h. These long-lasting changes in CaMKII autophosphorylation and subcellular distribution after a brief seizure suggested that CaMKII could be involved in carrying forward the signal resulting from brief seizure activity, at least for a few hours, as would be required for kindling to occur. In PTZ kindled rats, convulsions produced changes in CaMKII Thr(286) phosphorylation and distribution in the same direction and of similar magnitude as after the acute convulsion, but lasting for a much longer time. In fact, reduced Thr(286) phosphorylation of alpha-CaMKII was observed up to 48 h, completely bridging the interval between PTZ injections. Similar, but intermediate changes were found in tissue from rats that were only partially kindled. These results implicate CaMKII as a molecular messenger in the acquisition of PTZ kindling.

Animals↗

PubMed2004

Characterization of a new class of selective nonsteroidal progesterone receptor agonists.

The identification of a new series of selective nonsteroidal progesterone receptor (PR) agonists is reported. Using a high-throughput screening assay based on the measurement of transactivation of a mouse mammary tumor virus promoter-driven luciferase reporter (MMTV-Luc) in human breast cancer T47D cells, a benzimidazole-2-thione analog was identified. Compound 1 showed an apparent EC50 of 53 nM and efficacy of 93% with respect to progesterone. It binds to PR with high affinity (Ki nM), but had no or very low affinity for other steroid hormone receptors. Structure-activity relationship studies of a series of benzimidazole-2-thione analogs revealed critical positions for high PR binding affinity and transactivation potency as well as receptor selectivity, as exemplified by 25. Compound 25 binds to human PR with high affinity (Ki nM) and had at least > 1000-fold selectivity for PR versus other steroid receptors. Molecular modeling studies suggested that these agonists overlap favorably with progesterone in the ligand-binding domain of PR. In T47D cells, compound 25 acted as a full agonist in the MMTV-Luc reporter assay, as well as in the induction of endogenous alkaline phosphatase activity with apparent EC50 values of 4 and 9 nM, respectively. In the immature rat model, compound 25 provided a significant suppression of estrogen-induced endometrium hypertrophy as measured by luminal epithelial height. In contrast, compound 25 was inactive in the luteinizing hormone release assay in young ovariectomized rats. These benzimidazole-2-thione analogs constitute a new series of nonsteroidal PR agonists with an excellent steroid receptor selectivity profile. The differential activities observed in the in vivo progestogenic assays in rat models suggest that these analogs can act as selective PR modulators.

Animals↗

PubMed2004

Diabetic retinopathy: VEGF, bFGF and retinal vascular pathology.

BACKGROUND: Previous research indicated that the development of diabetic retinopathy (DR) is closely related to the excessive expression of growth factors. This paper was to study the relationship of DR with vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and the retinal vascular pathological change. METHODS: Fifty-five Wistar rats, weighing 100 - 200 g, were selected and randomly divided into four groups: control group (no streptozocin injection, n = 10), M1 group (streptozocin induced diabetes for 1 month, n = 15), M3 group (streptozocin induced diabetes for 3 months, n = 15), and M5 group (streptozocin induced diabetes for 5 months, n = 15). In situ hybridization and immunohistochemistry were used to investigate the expressions of bFGF and VEGF on retinal vascular, and retinal vessels were observed by transmission electron microscope. RESULTS: There was no difference in the number of pericytes between M1 and control group (P > 0.05), but the number of pericytes decreased obviously in M3 and M5 groups compared with the control group (P < 0.01, P < 0.001, respectively). Capillary embolization and non-cell capillary were seen in M5 group. Positive expression of VEGF was found in M5 group using in situ hybridization and immunohistochemistry respectively. Positive expression of bFGF could be seen in M3 (78%) and M5 group (89%). Most remarkable changes of vessels were observed in M5 group including fragmental thickness, split of basement membrane, swelling and distortion of endothelial cells. CONCLUSIONS: In retinal vascular of the streptozocin (STZ) rats, there shows the expression of bFGF at the third month and that of VEGF at the fifth month.

Animals↗

PubMed2003

[Effects of vascular endothelial growth factor and basic fibroblast growth factor in early stage diabetic retinopathy and their molecular pathological mechanism].

OBJECTIVE: To study the effects of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in early stage diabetic retinopathy and their mechanisms, so as to guide the clinical work theoretically. METHODS: Fifty-five Wistar rats were randomly divided into four groups. Ten rats were used as controls (M group). Streptozocin was injected intraperitoneally to induce diabetes for I month (M(1) group, n = 15), 3 months (M(3) group, n = 15), and 5 months (M(5) group, n = 15). At the experimental ends of each group, the rats were over-anesthetized and their eyeballs were extracted to make digest preparation. In situ hybridization and immunohistochemistry were used to investigate the expression of bFGF and VEGF on retinal vascular. Transmission electron microscopy was used to observe the histology of the retinal vessels. RESULTS: There was no difference in the number of pericytes between M(1) group and M group (P > 0.05), but the number of pericytes was significantly lower in M(3) and M(5) groups than in the M and M(1) groups (P < 0.001). VEGF in situ hybridization showed an expression rate of 34% in the M(5) group. VEGF immunohistochemistry showed an expression rate of 56% in M(5) group. bFGF in situ hybridization showed an expression rate of 78% in M(3) group and an expression rate of 89% in M(5) group. Transmission electron microscopy showed no change in M group. However, it showed swelling of endothelial cells, finger-like process into the capillary cavity, and uneven distribution of heterochromatin in pericytes in M(1) group. Obvious fragmental thickening and splitting of basement membrane, swelling and deformation, finger like process to the capillary cavity, and concentration and margination of heterochromatin in endothelial cells and swelling and deformation of rough surfaced endoplasmic reticulum and mitochondrion in pericytes were seen in the M(3) and M(5) groups, especially the latter. CONCLUSION: During the course of diabetic retinopathy, morphologic changes of vessels occurs prior to the expression of growth factors, in which the expression of VEGF follows the expression of bFGF.

Animals↗

PubMed2003

Improved method for the routine determination of acetylcholine and choline in brain microdialysate using a horseradish peroxidase column as the immobilized enzyme reactor.

A modified microbore high-performance liquid chromatography-immobilized enzyme reactor-electrochemical detection system for acetylcholine (ACh) and choline (Ch) was developed. The system used the horseradish peroxidase and a solution mediator ferrocene to convert the analyte into an oxidized ferrocene species which was detected electrochemically by reduction at 0 mV. There was an excellent linear relationship between the concentration of ACh/Ch and the peak height over the range of 1-5000 nmol/l. The limit of detection for ACh was 2 fmol/5 microl (S/N=3:1). Compared with the common method recommended by Bioanalytical System Inc. (BAS), this method exhibits a 200-fold improvement in the detection limit. The ACh and Ch levels in rat brain microdialysate were examined.

Acetylcholine↗