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Biomedical subjects

Jun Wu

Publications and source records attributed to Jun Wu.

At least 181 records · Page 10Linked to original sources
PubMed2003

Kinetics of the action of three selenides on Staphylococcus aureus growth as studied by microcalorimetry.

The effect of three kinds of selenide on Staphylococcus aureus growth was studied by means of microcalorimetry. Differences in their capacities to inhibit the metabolism of this bacterium were observed. The rate constant k (in the log phase) in the presence of the compounds decreased with increasing concentrations of the compounds. The relationship of k and c is nearly linear for the selenium compounds. Judged from the rate constant, k, and the half-inhibitory concentration IC50, the experimental results reveal that the sequence of antibiotic activity of the three tested selenides compounds is (2-hydroxy benzyl imino)ethyl n-hexyl selenide> n-butyl(2- hydroxy benzyl imino)ethyl selenide > bis[(2,4-dihydroxy benzyl imino)ethyl] selenide.

Anti-Bacterial Agents↗
PubMed2003

[An experimental study on the role of indirect antigen presentation pathway on the immunogenetic of epidermal cells].

OBJECTIVE: To explore the role of indirect antigen presentation pathway on the immunogenecity of epidermal cells. METHODS: Human epidermal cells (HEC), allogeneic human peripheral blood lymphocytes (PBL) and mononuclear cells (PBM, including monocytes) were isolated and cultured in vitro. HECs were transfected by human-originated CTLA4Ig-adenovirus vector. The CTLA4Ig expression was observed. Allogeneic PBLs or PBMs were added to the transfected and non-transfected HECs with simple cultured PBLs and PBMs as the control. The proliferation of PBL and PBM was determined by (3)H-TdR incooperation. RESULTS: HECs could be successfully transfected by CTLA4Ig-adenovirus vector and expressed corresponding proteins. The non-transfected HECs could stimulate slight proliferation of allogeneic PBLs (P < 0.05) and stimulate remarkable proliferation of PBMs (including monocytes) (P < 0.05). The proliferation reaction of PBLs and PBMs decreased significantly (P < 0.05) after being stimulated by HEC which was modulated by CTLA4Ig genes. CONCLUSION: Indirect antigen presentation pathway might play important roles in the HEC immunogenicity which could be evidently inhibited by CTLA4Ig.

Adenoviridae↗
PubMed2003

Dehydrochlorination of 1,1,1-trichloroethane and pentachloroethane by microbially reduced ferruginous smectite.

Reduction of structural Fe(III) in smectite clay minerals has been identified as a means to promote dechlorination of polychlorinated ethanes, but its environmental significance has yet to be fully assessed because Fe reduction has normally been achieved by agents uncommon in the environment (e.g., dithionite). This study reports the dehydrochlorination of pentachloroethane and 1,1,1-trichloroethane in the presence of ferruginous smectite reduced by two cultures of microorganisms, Shewanella oneidensis strain MR-1 (MR-R) and an enrichment culture from rice paddy soils (PS-R), in aqueous suspension under anoxic conditions. Microbially reduced ferruginous smectite facilitated dehydrochlorination of 1,1,1-trichloroethane to 1,1-dichloroethene with up to 60% conversion within 3 h of incubation time. In contrast, no formation of 1,1-dichloroethene was observed after incubation of 1,1,1-trichloroethane with chemically reduced ferruginous smectite for 24 h. Microbially reduced ferruginous smectite by MR-R and PS-R promoted the dehydrochlorination of pentachloroethane to tetrachloroethene by 80 and 15%, respectively, after 3 h of incubation time. The conversion of pentachloroethane to tetrachloroethene in the presence of chemically reduced ferruginous smectite after 24 h was 65%. These results indicate that structural Fe(II) in clay minerals has the potential to be an important reductant controlling the fate of organic chemicals in contaminated sediments.

Chlorine↗
PubMed2003

[Preparation of acyclovir liposome and study on its stability].

AIM: To prepare acyclovir liposome for improvement the entrapment efficiency and stability. METHODS: Acyclovir liposome was prepared by the reverse evaporating method. Surfactants such as sodium deoxycholate and oleic acid were added to optimize the conditions and technology of preparing acyclovir liposome. The entrapment efficiency and particle size of the acyclovir liposome were determined. The liposome stability was proved by centrifugal acceleration experiment. RESULTS: The particle size of the acyclovir liposome was 219.8 nm with the polydispersity index of 0.158. The entrapment efficiency reached 65%. The liposome was stable. CONCLUSION: The results suggest that the conditions and technology are stable and practical to prepare the liposome with high entrapment efficient and stability.

Acyclovir↗
PubMed2003

[The effect of calcium ionophore on dendritic cells derived from peripheral blood mononuclear cells].

AIM: To explore the effect of calcium ionophore (CI) on dendritic cells (DC) derived from peripheral blood monocytes. METHODS: Peripheral blood monocytes from healthy donors were treated with 100 microg/L rhGM-CSF, 100 microg/L rhGM-CSF plus (10 microg/L) CI, and 100 microg/L rhGM-CSF plus (100 microg/L) respectively. After cultivation of 40 hours, cellular morphology was observed under light microscope and electron microscope. Surface markers on treated PBMCs were analyzed by flow cytometry. MTT colorimetry was used to detect proliferation of autologous T cells. RESULTS: Peripheral blood monocytes treated with 100 microg/L rhGM-CSF plus 100 microg/L CI for 40 hours showed typical morphology of DCs. Simultaneously there was a decrease in CD14 expression and increase in HLA-DR, CD40, CD83 and CD86 expressions on these cells. In addition, PBMCs treated with 100 microg/L rhGM-CSF pass 100 microg/L CI for 40 hrs. Could evidently stimulate proliferation of autologous T cells. CONCLUSION: CI can markedly enhance transformation of peripheral blood monocytes induced by GM-CSF into DCs.

Antigens, CD↗
PubMed2003

[Study of recombinant stem cell factor].

Stem cell factor is an important hematopoietic growth factor. In this study, the human stem cell factor was produced by recombinant E. coli, and the structure and biological activity of the recombinant stem cell factor(rhSCF) was studied. It was indicated that the rhSCF was a uncovalent dimer in phosphate buffer,and had the correct mass spectra, mass peptides spectra, composition of amino acid, N-terminal sequernce, C-terminal sequence and intrachain disulfide linkages, rhSCF alone or synergy with rhG-CSF could mobilze hematopoietic progenitors to blood in monkey.

Animals↗
PubMed2002

[Relationship of hypertensive microalbuminuria and endothelial and glomerular impairment].

OBJECTIVE: To investigate the relationship between hypertensive microalbuminuria and vascular endothelial and glomerular impairment. METHODS: The animals were divided into the normotensive group (WKY Rat), hypertensive treated group (SHR with losartan) and untreated group(SHR). The blood pressure, level of microalbuminuria, and renal function were measured. In addition, endothelium of the mesenteric artery and glomerular mesangial cells were observed with the transmission electronic microscope in three and eight-month-old rats respectively. RESULTS: Significantly increased microalbuminuria was shown in SHR, which was correlated with the blood pressure and vascular endothelial volume density. Early impairment of vascular endothelium and the glomerular basement membrane was demonstrated in three-month-old SHR. However, there was no significant difference in glomerular mesangial cells and renal function between SHR and WKY rats. In the eight-month-old untreated group, the volume density of glomerular mesangial cells increased significantly, which indicated a further impairment of hypertension. The level of microalbuminuria was not correlated with the blood pressure. Compared with the untreated group, the hypertensive treated group showed a decreased volume density of vascular endothelium and glomerular mesangial cells, which was accompanied with a reduction of microalbuminuria. CONCLUSION: The mechanism which causes microalbuminuria in hypertension may vary with the severity of the hypertensive condition. At the early stage, the haemodynamics mechanism seems to be the most plausible cause of microalbuminuria, whereas at the severe stage, glomerular damage and vascular remodeling are likely to play the key role. Losartan can inhibit those deteriorations besides blood pressure lowering.

Albuminuria↗
PubMed2002

Myocardial protection of MCI-186 in rabbit ischemia-reperfusion.

We observed that 3-methyl-1-1phenyl-2-pyrazolin-5-one (MCI-186), a newly-developed free radical scavenger, attenuated necrosis in the in vivo rabbit hearts upon reperfusion after prolonged ischemia. In rabbits undergoing 1 hour ligation of the anterior ventricular coronary artery, a single bolus injection of MCI-186 (1.5 mg/kg) was introduced into the post-ischemic heart immediately before 4 hour reperfusion. Compared to negligible necrosis in sham-operated control animals and 33.81 +/- 13.50% necrosis in the area at risk for the saline control group (n = 8), the MCI-186 - treated group (n = 8) had a necrosis of 13.27 +/- 4.60% (p < 0.05 vs saline control group). The pressure-rate index had a slight decrease in MCI-186 treated group compared to the control group (p > 0.05). However, the blood levels of malondialdehyde (MDA) in MCI-186 treated group (2.08 +/- 0.23 microM) was significantly smaller than that of 2.65 +/- 0.31 microM in control animals (p < 0.01), while sham control had an average MDA level of 1.91 +/- 0.40 microM, with p > 0.05 relative to that in the MCI-186 treated group. These data support our contention that MCI-186 reduces reperfusion injury in perfused hearts with prolonged ischemia and the mechanism for the in vivo efficacy of MCI-186 is predominantly related to its antioxidant activities.

Animals↗
PubMed2002

Recombinant arginine deiminase as a potential anti-angiogenic agent.

Arginine deiminase (ADI), isolated from Mycoplasma cell extracts, has been suggested to inhibit endothelial cell growth in vitro. However, anti-angiogenic activity by ADI has not yet been demonstrated. In this study, we investigated the in vitro effect of recombinant ADI (rADI) on the growth, migration, and tube formation of human umbilical vein endothelial (HUVE) cells. Mycoplasma arginine deiminase was cloned by PCR and the rADI was expressed in Escherichia coli. and purified to near homogeneity. The purified recombinant protein was found to have characteristics similar to those of the native enzyme: molecular weight (48 kDa) and specific enzymatic activity of converting L-arginine into citrulline (32.7 U/mg). This recombinant enzyme also exhibited an inhibitory effect on the growth of HUVE cells. The anti-angiogenic activity was demonstrated by in vitro inhibition of migration into the scratch wounded area in HUVE cell monolayers and the inhibition of microvessel tube-like formation of HUVE cells on Matrigel-coated surfaces. These results suggest that arginine deiminase is a potential inhibitor for angiogenesis, and that arginine concentrations may play an important role in regulating neovascularization.

Angiogenesis Inhibitors↗
PubMed2002

Induction of apoptosis and inhibition of cell growth by developmental regulator hTBX5.

T box (Tbx) genes are a large family of transcription regulators that play critical roles in invertebrate and vertebrate development. Mutations in Tbx5 gene have been found to cause Holt-Oram syndrome (HOS) in humans. Partial dysfunction of TBX5 in mouse also causes HOS phenotype. Little is known about its molecular and cellular mechanism. Here, we report that ectopic expression of TBX5 inhibited colony formation, induced apoptosis, and decreased the growth rate of cells. The two point mutations in T domain and a truncated mutation in C-terminal found in human HOS patients produced TBX5 mutant proteins with a significantly reduction of colony suppression activity. Deletion of the DNA-binding domain, however, nearly completely abrogated its ability to suppress colony formation. These results reveal TBX5 as a new regulator of apoptosis and cell growth, suggesting a possible mechanism for Holt-Oram syndrome, and a potential reagent for controlling tumor growth.

Animals↗
PubMed2002

A new and sensitive method for the quantification of HBV cccDNA by real-time PCR.

The persistence of covalently closed circular (ccc) DNA of Hepatitis B virus (HBV) in liver cells is believed to be the major reason for relapse after completion of HBV antiviral therapy. Up to now, there is no sensitive method to quantify cccDNA in infected liver cells. We designed a set of primers to specifically amplify DNA fragments from HBV cccDNA but not from viral genomic DNA. A good linear range was obtained when 100-10(7) copies of HBV cccDNA were used as template in the quantitative real-time PCR. Not only is this method rapid, economical, highly sensitive, it can be used to monitor HBV cccDNA in infected human liver biopsies and to guide patients undergoing long-term anti-HBV therapy.

Cells, Cultured↗
PubMed2002

Identification of bradykinin receptors in clinical cancer specimens and murine tumor tissues.

Bradykinin (BK) has multiple pathophysiologic functions such as induction of vascular permeability and mitogenesis, and it triggers the release of other mediators such as nitric oxide in inflammatory and cancer tissues. To explore the pathophysiologic roles of BK in tumor, we examined the distribution of BK B2 receptors in human adenocarcinoma (lung, stomach), lymphoma (lymph node), hepatoma, squamous cell carcinoma (lung) and carcinoid (duodenum), and in mouse colon adenocarcinoma 38 (C-38) and sarcoma 180 (S-180) tumor tissues. Immunohistochemical staining of tumor tissues with an anti-BK B2 receptor antibody, or autoradiography with the B2 receptor antagonist [125I]HOE 140 (D-Arg-[Hyp Thi D-Tic Oic8]-BK) and the B2 receptor agonist [3H]BK indicated the presence of B2 receptors in all human tumor cells and murine S-180 and C-38 cells. Specific binding of [3H]HOE 140 was observed in S-180 cells with a Kd of 2.1 nM. Binding of [125I]HOE 140 to S-180 cells was competed by an excess amount (20-100 times) of nonradiolabeled HOE 140 or BK, but not by BK B1 receptor agonist des-Arg9-BK. These results provide direct evidence that the BK B2 receptor is expressed in human cancer and experimental murine tumors, which suggests a potential role for BK in inducing pathologic signal transduction in cancer growth and progression, nitric oxide production and vascular permeability enhancement in tumors. BK antagonists may thus have applications in the modulation of cancer growth and in paraneoplastic syndromes.

Animals↗
PubMed2002

In vitro high-throughput screening assay for modulators of transcription.

We developed a 96-well microtiter-plate high-throughput screening (HTS) assay for the detection of modulators of transcription. This HTS assay consists of three steps: (1) the in vitro transcription reaction; (2) modification and hybridization of RNA products; and (3) washing and quantification. During the first step, a DNA template containing the promoter of interest upstream of a cassette lacking guanosine residues in one of its strands (G-less cassette) is incubated with nuclear extract and the necessary cofactors/activators and substrates. During the second step, the in vitro synthesized transcripts are digested with RNase T1 and hybridized to two DNA oligonucleotides. One oligonucleotide is biotinylated for trapping of the RNA products to a streptavidin-coated plate, and the other is europium-labeled for detection by time-resolved fluorescence. We show that this assay is highly reproducible and robust, yielding results comparable to those obtained by standard methodologies employing radioactive nucleotide incorporation and gel electrophoresis while offering a very significant advantage in terms of throughput (>2000 assay points per operator per day). We demonstrate the usefulness of the assay for the discovery of small molecule inhibitors of transcription, and applications of this approach for the high-throughput discovery of transcriptional modulators are discussed.

Amanitins↗
PubMed2002

Dechlorination of pentachloroethane by commercial Fe and ferruginous smectite.

Short-term experiments were conducted to investigate the effect of a commercial Fe and an iron-bearing clay mineral, ferruginuous smectite (SWa-1), on the degradation of pentachloroethane (PCA). After 3 h of contact time, SWa-1 catalyzed PCA dehydrochlorination to tetrachloroethene (PCE, 65% conversion), whereas commercial Fe promoted PCA stepwise dechlorination via dehydrochlorination (approximately 40% conversion) and subsequent PCE hydrogenolysis to trichloroethene (TCE). The addition of unaltered SWa-1 to commercial Fe led to a complete inhibition on TCE production, whereas the addition of reduced SWa-1 barely resulted in a 30% decrease.

Chlorine↗
PubMed2002

Covalent immobilization of chitosan/heparin complex with a photosensitive hetero-bifunctional crosslinking reagent on PLA surface.

Chitosan (CS) was covalently immobilized onto polylactic acid (PLA) film surface using the photosensitive hetero-bifunctional crosslinking reagent, 4-azidobenzoic acid, which was previously bonded to chitosan by reaction between an acid group of the crosslinking reagent and a free amino group of chitosan. The immobilization was accomplished by irradiating with ultraviolet light, the modified chitosan being coated on the film surface to photolyze azide groups, thus crosslinking chitosan and PLA together. The hydroxyl and amino groups of chitosan may provide the opportunity for them being further derived by chemically immobilizing a variety of functional groups. These modifications could be carried out to tailor PLA biomaterial to meet the specific needs of different biomedical applications. For example, chitosan molecules immobilized on the PLA could be modified by heparin (Hp) solution to form a polyelectrolyte complex on the PLA surface. Platelet adhesion assay showed that PLA surface modified by chitosan/heparin complex could inhibit platelet adhesion and activation. Cell culture assay indicated that PLA surface with CS/Hp complex showed enhanced cell adhesion.

Animals↗
PubMed2002

TSC2 is phosphorylated and inhibited by Akt and suppresses mTOR signalling.

Tuberous sclerosis (TSC) is an autosomal dominant disorder characterized by the formation of hamartomas in a wide range of human tissues. Mutation in either the TSC1 or TSC2 tumour suppressor gene is responsible for both the familial and sporadic forms of this disease. TSC1 and TSC2 proteins form a physical and functional complex in vivo. Here, we show that TSC1-TSC2 inhibits the p70 ribosomal protein S6 kinase 1 (an activator of translation) and activates the eukaryotic initiation factor 4E binding protein 1 (4E-BP1, an inhibitor of translational initiation). These functions of TSC1-TSC2 are mediated by inhibition of the mammalian target of rapamycin (mTOR). Furthermore, TSC2 is directly phosphorylated by Akt, which is involved in stimulating cell growth and is activated by growth stimulating signals, such as insulin. TSC2 is inactivated by Akt-dependent phosphorylation, which destabilizes TSC2 and disrupts its interaction with TSC1. Our data indicate a molecular mechanism for TSC2 in insulin signalling, tumour suppressor functions and in the inhibition of cell growth.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Pulmonary effects of in utero tracheal occlusion are dependent on gestational age in a rabbit model of diaphragmatic hernia.

PURPOSE: The authors investigated the effect of gestational age on lung development and maturation after in utero tracheal occlusion (TO) in a rabbit model of congenital diaphragmatic hernia (CDH). METHODS: In 46 fetal rabbits, CDH was created at 23 days' gestational age (GA; term, 31 days), corresponding to the pseudoglandular phase of lung development. A second intervention was performed at either 26, 27, or 28 days on 6 fetuses in each GA group. At that time, either TO (CDH + TO), or a sham operation (CDH + sham) was performed. Nonoperated littermates served as internal normal controls (CTR). All fetuses were delivered by cesarean section at 30 days GA to assess lung response by lung-to-body-weight ratio, pulmonary morphometry, and the density of type II pneumocytes. RESULTS: After TO, the lungs were significantly larger than in CDH animals; their weight was proportional to the duration of TO. Pulmonary morphometry in TO fetuses was comparable with that of controls. The density of type II cells was inversely related to the gestational age at which TO was performed, with normal values with TO at GA at 28 days. CONCLUSION: Timing of TO is critical to subsequent pulmonary development: early in gestation TO leads to pulmonary overgrowth and type II pneumocyte depletion, whereas normal values are obtained when TO is delayed till 28 of 32 days.

Animals↗