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Biomedical subjects

Lin Wang

Publications and source records attributed to Lin Wang.

At least 217 records · Page 12Linked to original sources
PubMed2004

Characterization of metal adsorption kinetic properties in batch and fixed-bed reactors.

Copper adsorption kinetic properties in batch and fixed-bed reactors were studied in this paper. The isothermal adsorption experiments showed that the copper adsorption capacity of a granular activated carbon (Filtrasorb 200) increased when ionic strength was higher. The presence of EDTA diminished the adsorption. An intraparticle diffusion model and a fixed-bed model were successfully used to describe the batch kinetic and fixed-bed operation behaviors. The kinetics became faster when the solution pH was not controlled, implying that the surface precipitation caused some metal uptake. The external mass transfer coefficient, the diffusivity and the dispersion coefficient were obtained from the modeling. It was found that both external mass transfer and dispersion coefficients increased when the flow rate was higher. Finally effects of kinetic parameters on simulation of fixed-bed operation were conducted.

Adsorption↗
PubMed2004

Solution-phase reductive cyclization of 2-quinoxalinol analogs: systematic study of parallel synthesis.

1,5-Difluoro-2,4-dinitrobenzene starting material was treated via primary and/or secondary substitution with a variety of amino acids or amines and the aromatic m-dinitro groups were then reductively cyclized provide the 2-quinoxalinol analogs. The conditions for 1,5-dialkylamino-2,4-dinitrobenzene reduction have been systematically studied and optimized in solution. Three effective methods are described for the high-throughout generation of 2-quinoxalinol analogs.

Biochemistry↗
PubMed2004

Prolonged and inducible transgene expression in the liver using gutless adenovirus: a potential therapy for liver cancer.

BACKGROUND AND AIMS: Gene therapy of liver diseases would benefit from systems allowing prolonged, regulable, and tissue-specific transgene expression. We attempted to produce a vector fulfilling these requirements. METHODS: We generated gutless adenoviral vectors containing a mifepristone (RU486)-inducible system for controlled and liver-specific expression of human interleukin-12 (hIL-12) (GL-Ad/RUhIL-12) and mouse IL-12 (mIL-12) (GL-Ad/RUmIL-12). The properties of these vectors were tested both in vitro and in vivo. RESULTS: Infection of cells with GL-Ad/RUhIL-12 resulted in high level of hIL-12 expression in the presence of RU486 only in hepatocytic cells. In animals injected with GL-Ad/RUhIL-12, the administration of RU486 induced a transient rise of serum hIL-12 that peaked at 10 hours and completely disappeared by 72 hours. The peak value of hIL-12 was dependent on the doses of the vector and the inducer. High and sustained serum levels of hIL-12 could be attained by continuing administration of RU486 every 12 or 24 hours. Repetitive induction of hIL-12 could be obtained over, at least, a period of 48 weeks after a single injection of GL-Ad/RUhIL-12. Although the vector was detected in many tissues after systemic injection, transcription of the transgene was only found in the liver. Treatment of liver metastases with 5 x 10(8) infectious units of GL-Ad/RUmIL-12 plus RU846 resulted in complete tumor regression in all animals. CONCLUSION: Gutless adenoviral vectors allow liver-specific and regulable transgene expression for prolonged periods of time. These vectors are promising tools for gene therapy of liver cancer and could also be useful for other forms of hepatic disease.

Adenoviridae↗
PubMed2004

Dose response characteristics of new models of GAFCHROMIC films: dependence on densitometer light source and radiation energy.

This paper presents a systematic study of the dose response characteristics of two new models and one commonly used model of GAFCHROMIC film: HS, XR-T, and MD55-2, respectively. We irradiated these film models with three different radiation sources: I-125, Ir-192, and 6 MV photon beam (6 MVX). We scanned the films with three different densitometers: a He-Ne laser with a wavelength of 633 nm, a spot densitometer with a wavelength of 671 nm, and a CCD camera densitometer with interchangeable LED boxes with wavelengths of 665 nm (red), 520 nm (green), and 465 nm (blue). We compared the film sensitivities in terms of net optical density (NOD) per unit dose in Gy. The sensitivity of each film model depends on radiation energy and the densitometer light source. Using He-Ne laser based densitometer as a reference standard, we found the sensitivities (NOD/Gy) for the red lights of wavelengths, 671 nm and 665 nm, are higher by factors of about 2.5 and 2, respectively. The sensitivities for green (520 nm) and blue (465 nm) lights are lower than that for He-Ne laser (633 nm) by factors of about 2 and 4, respectively. The energy dependence of the sensitivity varies with the film model, but is similar for all densitometer light sources. Comparing I-125 to Ir-192 and 6MVX, we note that (a) model XR-T is about eight times more sensitive, and (b) models HS and MD55-2 are about 40% less sensitive. Relative to MD55-2, XR-T is 12 times more sensitive for I-125 but comparable for Ir-192 and 6MVX, whereas HS is 2 to 3 times more sensitive in all cases. This set of results can serve as useful information for making decisions in selecting the film model and compatible densitometer to achieve the best accuracy of dosimetry in the appropriate dose range.

Densitometry↗
PubMed2004

Adrenomedullin affects two signal transduction pathways and the migration in retinal pigment epithelial cells.

PURPOSE: Adrenomedullin is a multifunctional regulatory peptide known to inhibit the migration of smooth muscle cells. In vitro studies were performed to identify whether adrenomedullin (ADM) also inhibits the migration of RPE cells. The aberrant behavior of these cells is an early event in proliferative vitreoretinopathy, and these studies were designed to determine how ADM acts on RPE cells at the second-messenger level. METHODS: Migration of cultured human RPE cells was determined by the Boyden chamber method, using 10% fetal calf serum (FCS) as a chemotactic factor. The attachment assay was performed on fibronectin, laminin, or poly-D-lysine-coated 96-well plates. RPE cells were incubated in PBS buffer with or without ADM for 15 minutes. Intracellular cAMP and cGMP changes were then measured by enzyme immunoassay (EIA). To determine the cytoplasmic free Ca2+ concentration ([Ca2+]i) response to ADM, fluo-3 AM-loaded RPE cells were imaged with a laser scanning confocal microscope, after stimulation with ADM (10(-12)-10(-7) M). RESULTS: ADM exhibited a concentration-dependent inhibition of FCS-stimulated RPE cell migration. The maximum inhibitory effect of ADM, observed at 10(-7) M, on basal and FCS-induced RPE cell migration was approximately 53.8% and 43.8% of the control, respectively. Exogenously added ADM (10(-9)-10(-7) M) had no significant effect on RPE cell attachment on all tested substrates. ADM increased intracellular cAMP and decreased intracellular cGMP levels dose dependently (10(-10)-10(-7) M) in RPE. The maximum effect was observed at 10(-7) M. ADM also induced a [Ca2+]i decrease in a dose-dependent manner (10(-12)-10(-7) M). The maximum effect was observed at 0.1 micro M, at which point the level declined to 42.9% of the control. CONCLUSIONS: ADM inhibits the migration of RPE cells in vitro by a mechanism that involves the reciprocal upregulation of cAMP and downregulation of cGMP, in association with reductions in [Ca2+]i. ADM-mediated fluctuations in [Ca2+]i, which are well known to be involved in cell migration, appear to be regulated in part by mechanisms involving cAMP synthase. Thus, it appears that ADM acts as a constitutive regulatory system to control aberrant RPE cell behavior and specific migration in response to inflammatory mediators.

Adrenomedullin↗
PubMed2004

Determination of operational parameters of anaerobic phase for enhanced phosphorus removal in MBR.

Two runs of experiments were carried out to obtain an understanding of phosphorus release and uptake under the anaerobic condition and then the aerobic condition respectively. Under anaerobic condition, it was found that the extent of phosphorus release appeared to increase with the increase of the initial organic loading rate when the initial organic loading rate was up to 0.1 gSCOD/gMLSS. When the initial organic loading rate was higher than 0.1 gSCOD/gMLSS, the amount of phosphorus release per unit mass of MLSS reached nearly a same stationary value, and it seemed this is not affected by organic loading rate when there is external available substrate remained. In addition, the effect of NOx-N on the phosphorus release and uptake was also investigated, it was proved that the denitrifiers has an advantage over polyphosphate accumulating bacteria in competition for organic substrate under anoxic condition. Therefore, the existence of NOx-N is disadvantageous to the phosphorus release. Based upon the above investigations, the process configuration of membrane bioreactor(MBR) in combination with anaerobic phase was proposed to enhance the removal of phosphorus in treating domestic wastewater. During the experimental period of four months, average removals of 92.50%, 84.25%, 100%, 94.09% and 85.33% were achieved for COD, TP, SS, NH3-N and TN respectively.

Bacteria, Anaerobic↗
PubMed2004

Experimental study on the mechanism of sex difference in the risk of torsade de pointes.

BACKGROUND: Torsade de pointes (TdP) is a form of polymorphic ventricular tachycardia featuring prolonged QT intervals. Female gender is associated with an increased risk of TdP. However, the causes of the sex difference in risk are poorly understood. Recently, transmural dispersion of repolarization (TDR) has been implicated in the genesis of TdP. Consequently, we compared TdP incidence and TDR between male and female rabbit hearts in order to investigate the mechanism of sex difference in TdP risk in rabbits in vitro. METHODS: By means of monophasic action potential recording techniques, the monophasic action potential of the epicardium, midmyocardium, and endocardium were simultaneously recorded using specially designed plunge-needle electrodes placed across the left ventricular free wall of both female (n = 8) and male (n = 8) rabbit hearts purfused by the Langendorff method. TdP was induced by bradycardia, d-sotalol, and low-K+, Mg2+ Tyrode solution. RESULTS: TDR measurements in all three myocardial layers of male and female rabbit hearts were (18 +/- 2) ms and (21 +/- 2) ms, respectively (n = 8, P > 0.05). After perfusion with d-sotalol, the 90% monophasic action potential duration was prolonged in both male and female rabbits. TDR in male and female rabbit hearts increased to (29 +/- 2) ms and (61 +/- 2) ms, respectively, a difference that is significant. Eight female rabbit hearts had early afterdepolarization and 7 of them developed TdP. Seven male rabbit hearts had early after depolarization, but only one of these hearts developed TdP. CONCLUSION: Greater TDR may play an important role in the higher incidence of TdP in female rabbit hearts.

Action Potentials↗
PubMed2004

[Study on the relationship between nitric oxide synthase gene G894T polymorphism and hypertension related risk factors in patients with essential hypertension in Chongqing city].

OBJECTIVE: To explore the relationship between genetic anomaly and risk factors in hypertension, a polymorphism at position G894T of the gene encoding the endothelial nitric oxide synthase (eNOS) together with hypertension related risk factors were observed in patients with essential hypertension (EH) in Chongqing city. METHODS: Two hundred and twenty-six patients with EH and matched controls were selected. Genotypes of polymorphisms were determined by polymerase chain reaction (PCR), while PCR products were digested by restriction endonuclease (BanII). Questionnaire referred to life style, dietary, smoking, alcohol consumption, psychological and mental state, waist-to-hip ratio (WHR), etc was administered. RESULTS: There was no significant difference noticed in genotype distribution for the eNOS gene G894T genotype between hypertensive groups and controls, but difference was found among certain related risk factors, such as salt intake, snoring and WHR, etc. Logistic regression analysis showed no association between 894T allele and hypertension. CONCLUSION: Although the polymorphism of eNOS gene G894T did not seem to play an important and direct role in the pathogenesis of EH it might have indirect effects through certain risk factors.

Adult↗
PubMed2004

Toll-like receptor 4 involvement in hepatic ischemia/reperfusion injury in mice.

BACKGROUND: Toll-like receptor 4 (TLR4) is involved in innate immunity by recognizing endotoxin resulting in a burst of inflammatory cascade. We investigated the relation between activation of TLR4 and liver injury in partial hepatic ischemia/reperfusion (I/R) injury in mice. METHODS: TLR4-deficient mice (C3H/Hej) and wild type mice (WT, C3H/Heouj) were used in the model of I/R injury. Partial hepatic ischemia was produced by occlusion of inflow to the median and left lobes for 45 minutes. Blood was drawn at 1 and 3 hours after reperfusion. The blood was analyzed for aspartate aminotransferase (AST) and tumor necrosis factor alpha (TNF-alpha). TNF-alpha mRNA expression and myeloperoxidase (MPO) level in the ischemic lobes were examined by northern blot and myeloperoxidase assay respectively. RESULTS: AST levels were significantly decreased in TLR4deficient mice compared with WT mice at both time points (WT: 1215.5+/-174.03, 2958.17+/-186.81 IU/L at 1 and 3 hours respectively vs TLR4def: 661.83+/-106.09, 1145.17+/-132.43 IU/L at 1 and 3 hours, mean+/-SD, 6 mice/group, t=-6.65 and -5.57, P<0.001). Consistent with the role of TNF-alpha in hepatic I/R, serum TNF-alpha was decreased in TLR4 deficient mice at 3 hours after reperfusion compared with WT (152.39+/-43.3 vs 249.12+/-51.89, n=6, t=-3.13, P<0.05). MPO level in the ischemic lobes in TLR4 deficient mice at 3 hours after reperfusion was significantly lower than that in WT mice (0.059 +/-0.004 vs 0.173+/-0.025, n=6, F=33.49, P<0.001). This difference appears to be mediated at the gene level since TLR4 deficient mice had decreased TNF-alpha mRNA expression at 1 hour after reperfusion compared with WT mice (80.3+/-28.8 vs 189.4+/-24.6, t=-3.25, P<0.05). CONCLUSIONS: Compared with WT mice, TLR4-deficient mice appear to have a mild I/R injury. Regulation of TNF-alpha at mRNA level seems to have a critical effect. These suggest TLR4 be involved in the mechanism of hepatic I/R injury in mice.

Animals↗
PubMed2004

[Induction of apoptosis of cultured hepatocarcinoma cell by essential oil of Artemisia Annul L].

OBJECTIVE: To know whether the essential oil of Artemisia annul L. can induce apoptosis of cultured hepatocarcinoma cell SMMC-7721. METHODS: Hepatocarcinoma cells were treated by the essential oil of Artemisia annul L. while positive control was treated by hydroxycamptothecine (HPT) and negative or mock control was treated by normal saline (NS). Induction of the apoptosis was analyzed by using flow cytometry (FCM), light microscope and electronic microscope, Giemsa's stain and DNA pattern after drug treatment. RESULTS: After the treatment of the cells with 100 micrograms/ml essential oil of Artemisia annul L. for 24 hours, the morphological changes of classic apoptosis such as condensation of cytoplasm, fragmentation of nuclear chromatin, and apoptosis body were seen. The sub-G1 peak was exhibited by FCM, and the DNA ladder pattern was observed. CONCLUSION: These findings demonstrated that the essential oil of Artemisia annul L. could induce apoptosis of cultured SMMC-7721.

Antineoplastic Agents, Phytogenic↗
PubMed2004

[Screening and characterization of dominant bacteria for the degradation of endocrine disruptor di-n-butyl phthalate].

OBJECTIVE: In order to screen the dominant bacteria for degrading endocrine disruptor di-n-butyl phthalate (DBP). METHODS: The activated sludge was acclimated by DBP as sole carbon source. DBP concentration was increased progressively. 5 strains were isolated from the sludge by the plane-table after 10 weeks, 1 strain of which grew and degraded DBP well. RESULTS: By orthogonal test, it was indicated that the appropriate degradation conditions of DBP for this best strain were degradation time 32 h, DBP concentration 200 mg/L, rate of shaking incubator 100 r/min, pH 7.0, temperature 30 degrees C. The degraded rate of DBP is more than 95% under above conditions. CONCLUSION: The bacterium was identified as Pseudomonas.

Bacteria↗
PubMed2004

[Clinicopathological study of 145 childhood rhabdomyosarcoma cases].

OBJECTIVE: To study the clinicopathological, immunohistochemical and electron microscopic characteristics of pediatric rhabdomyosarcomas (RMS). METHODS: One hundred and forty-five cases of pediatric rhabdomyosarcomas were studied by routine histological, immunohistochemical and electron microscopic studies. RESULTS: There were 97 male and 48 female patients with ages ranging from 4 months to 13 years and a mean of 4.2 years. The follow-up period of 100 patients was from 1 year to 20 years with a mean of 5 years after diagnosis. All cases were subtyped into the following histological categories: embryonal RMS, botryoid RMS, spindle cell RMS, alveolar RMS and solid RMS. Histopathological subtypes, tumor site and tumor stage correlated significantly with the patients' 5 years survival. The best prognosis was observed in spindle cell and botryoid RMS. Embryonal RMS carried an intermediate prognosis. Patients with alveolar RMS and solid RMS had the worst prognosis. Tumors involving bladder, head and neck carried a favorable clinical outcome. Patients with tumors involving trunk extremities retroperitoneum and pelvis did poorly. Immunohistochemically, all cases were positive for Vimentin. The positive staining rates for desmin, SMA and myoglobin were 78%, 75% and 37%, respectively. All tumors were negative for NSE, CD99 and LCA. Electron microscopy study showed features of myofilament and sarcomere in 10 of 15 cases. CONCLUSIONS: RMS is the most common soft tissue sarcoma of childhood. Immunohistochemistry and electron microscopy are helpful in diagnosis and classification of RMS.

Adolescent↗
PubMed2004

[Expression of adrenomedullin and adrenomedullin receptor in the epiretinal membranes of proliferative vitreoretinopathy].

OBJECTIVE: To investigate the expression of adrenomedullin (ADM) and ADM receptor (ADMR) in epiretinal membranes (ERM) of proliferative vitreoretinopathy (PVR). METHODS: The expression of ADM and ADMR in 10 ERM were studied by in situ hybridization analysis (ISH). RESULTS: ADM and ADMR mRNAs were expressed in 7 of 10 specimens. The positive signals were distributed unevenly in positive cells. Some cells expressed mainly in the cytoplasm and the others expressed mainly in the nucleus. CONCLUSION: ADM and ADMR are expressed in the ERM of PVR, indicating that ADM and ADMR may play a role in the pathogenesis of PVR.

Adrenomedullin↗
PubMed2004

[Mutual interaction between hepatitis B virus antigen and metallothionein].

OBJECTIVE: To screen and identify the protein interacting with HBV antigen in hepatocytes. Then investigate the biological functions of hepatitis B virus antigen in the pathogenesis of hepatitis B and seek effective methods to prevent and treat it. METHODS: The yeast two-hybrid system-3 technique was used to construct HBV PreS2, HBeAg, HBcAg, HBxAg bait plasmids. The bait plasmids transformed the yeast AH109 and expressed themselves in it. After being identified by SDS-PAGE and Western blot, the AH109 yeast was mated with yeast Y187 containing liver cDNA library plasmid in 2 x YPDA medium to form diploid yeast and was then plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) and synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing x-alpha-gal for screening. Plasmids of blue colonies were extracted and transformed into Escherichia coli, then analyzed by DNA sequencing and bioinformatics. To further prove the interaction between HBV antigen and metallothionein, translation was performed by using reticulocyte lysate and coimmunoprecipitation was displayed in vitro. RESULTS: Genes coding for HBV antigen binding protein were successfully cloned and metallothionein was found in that protein. The interaction between HBeAg, HBcAg and HBxAg and metallothionein were further proved by coimmunoprecipitation in vitro. CONCLUSION: The interaction between HBV antigen and metallothionein indicates that metallothionein may participate in the pathogenesis of hepatitis B

Hepatitis B↗
PubMed2004

[Dendritic cells, natural killer cells and adhesion molecules in psoriasis].

OBJECTIVE: To study the role of the dendritic cells, natural killer cells and adhesion molecules play in the pathogenesis of psoriasis. METHODS: The expression levels of human leukocyte antigen (HLA)-DR, CD1a, CD16, CD57, tumor necrosis factor (TNF)-alpha and intercellular adhesion molecule (ICAM)-1 were detected by immunohistochemistry in lesions of 26 patients with psoriasis before and after treatment. RESULTS: The expression of HLA-DR, CD1a, CD16, CD57, TNF-alpha and ICAM-1 showed no significant difference between the active phase and the static phase of psoriatic lesions (P>0.05). After treatment, the positive expression of all markers decreased evidently or even disappeared with histopathological improvement in the resolvent phase of psoriatic lesions. There were statistically significant difference by Wilcoxon rank sum test (P<0.05). CONCLUSION: Dendritic cells, natural killer cells and adhesion molecules play an important role in the pathogenesis of psoriasis.

Adult↗
PubMed2004

Effects of imidapril on heterogeneity of action potential and calcium current of ventricular myocytes in infarcted rabbits.

AIM: To investigate the effects of chronic treatment with imidapril on the electrophysiologic heterogeneous change of the noninfarcted myocardium of rabbits after myocardial infarction and the mechanism of its antiarrhythmic efficacy. METHODS: Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 weeks. Myocytes were isolated from subendocardial, midmyocardial, and subepicardial regions of the noninfarcted left ventricular wall. Action potentials and calcium current were recorded using whole-cell patch clamp technique. RESULTS: The action potential duration of repolarization 90 % (APD90) was more prolonged in midmyocardium rather than in subepicardium and subendocardium with healed myocardial infarction. The transmural dispersion of repolarization (TDR) was increased in the three ventricular regions. The amplitude of I(Ca-L) [was enhanced but its density was decreased in noninfarcted ventricular myocytes due to increased cell membrane capacitance. The increased differences of calcium currents among subepicardium, midmyocardium, and subendocardium were also discovered. Normalization of heterogeneous changes in repolarization after treatment with imidapril was observed and decrease of TDR in noninfarcted area was measured. Early after depolarization (EAD) events of noninfarcted midmyocardium were markedly decreased by imidapril. CONCLUSION: Imidapril reduced the electrophysiologic heterogeneities in noninfarcted area in rabbits after myocardial infarction. This ability of imidapril may contribute to its antiarrhythmic efficacy.

Action Potentials↗