Biomedical subjects

W Wu

Publications and source records attributed to W Wu.

At least 307 records · Page 17Linked to original sources

PubMed1997

[The role of adenosine in the early stage of anoxia of hippocampal slices and its mechanisms].

The role of adenosine in reversible inhibition of synaptic function during the early stage of anoxia and its mechanisms were investigated with extracellular recording technique in rat hippocampal slices. The results showed that acute anoxia led to the reversible inhibition of synaptic function, which is similar to the response to addition of high concentration of exogenous adenosine. The reversible inhibition could be suppressed by adenosine A1 receptor antagonist CPT and potassium channel blocker 4-AP, whereas TEA and ATP-sensitive potassium channel blocker glipzide had no effect. These results suggest that during the early stage of anoxia, the enhanced release of endogenous adenosine can inhibit the synaptic transmission by activating 4-AP-sensitive potassium channels via A1 receptors and thus play a role in protenction against anoxic injury. ATP-sensitive potassium channels may not be involved in the mechanisms of adenosine action.

Adenosine↗

PubMed1997

Protective effect of radix Salviae miltiorrhizae on apoptosis of neurons during focal cerebral ischemia and reperfusion injury.

We have found that Radix Salviae Miltiorrhizae (RSM) plays a protective role in ischemic brain injury, which attracted us to investigate the effect of RSM on apoptosis of neurons during cerebral ischemia and reperfusion. The apoptotic cells in ischemic brains at different reperfusion intervals were tested with the method of TdT-mediated dUTP-DIG nick end labeling (TUNEL), and the effect of RSM on the apoptosis of neurons was studied in left middle cerebral artery (LMCA) occlusion in rat models (n = 18). The results showed that few scattered apoptotic cells were observed in right cerebral hemisphere after LMCA occlusion and reperfusion, and that a lot of apoptotic cells were found in left ischemic cerebral cortex and caudoputamen at 12 h reperfusion, and they reached peak at 24-48 h reperfusion. However, in rats pretreated with RSM, the number of apoptotic cells in left cortex and caudoputamen reduced significantly and the neuronal damage was much milder at 24 h reperfusion as compared with those of saline-treated rats. From this study, we conclude that administration of RSM can reduce the apoptotic of neurons induced by cerebral ischemia and reperfusion and afford significant cerebroprotection in the model of focal cerebral ischemia and reperfusion.

Animals↗

PubMed1997

Effect of acupuncture on vasoactive intestinal peptide in ischemic cerebrovascular diseases.

BACKGROUND AND PURPOSE: Vasoactive intestinal peptide (VIP) appears to play an important role as a neurotransmitter or neuromediater in ischemic cerebrovascular diseases (ICVD). The effect of acupuncture, which is used in treatment of ICVD with good efficiency, on VIP has not been known. For finding the mechanism of acupuncture in treatment of ICVD and the effect of electro-acupuncture on VIP, the present study was performed. MATERIALS AND METHODS: 59 patients with acute ICVD were randomly divided into two groups. Electro-acupuncture and routine treatment were given in Group 1 (n = 29), and routine treatment was used alone in Group 2 (n = 30). The cerebrospinal fluid (CSF) and blood were taken before the beginning of treatment and after a course of treatment in both groups. The control group consisted of 38 cases of non-ICVD. VIP was measured by radioimmunoassay. RESULTS: The level of CSF VIP in patients with acute ICVD was significantly lower than that in the controls, while the levels of plamsa VIP showed no significant difference between the ICVD and control groups, and the level of CSF VIP was not significantly correlated with the level of plasma VIP. After acupuncture treatment, the level of CSF VIP was increased and showed no significant difference as compared with the control group. CONCLUSION: Acupuncture might alleviate the disturbance of metabolism of VIP in CNS.

Acupuncture Therapy↗

PubMed1997

ET-1 gene expression of rat brain during ischemia and reperfusion and the protective effect of radix Salviae miltiorrhizae.

Endothelin-1 (ET-1) gene expression of rat brain during ischemia and reperfusion as well as the effect of Radix Salviae Miltiorrhizae (RSM) were studied with in situ hybridization. It was found that ET-1 gene expression of cerebral cortex and caudate-putamen was markedly increased both in 24 hours of ischemia and 24 hours of reperfusion groups (P < 0.01, P < 0.05). In RSM-treated rats, although the ET-1 gene expressions of ischemia and reperfusion sides were also increased as compared with contralateral cortex and caudate-putamen, they were significantly lower in RSM-treated rats than those of controls (P < 0.05, P < 0.01 respectively). The present study indicated that RSM can partly inhibit ET-1 gene expression of cerebral cortex and caudate-putamen during ischemia and reperfusion. This may be one of the protective mechanisms of RSM on cerebral ischemia and reperfusion.

Animals↗

PubMed1997

[Changes in t-PA, PAI-1 gene expression of coronary arteries with preconditioning in acute myocardial infarction rat].

The changes of t-PA, PAI-1 gene expression and t-PA activity were investigated in coronary arteries of Acute Myocardial Infarction (AMI) rat by nucleic acid molecular hybridization and spectrophotometric assay. The effect of preconditioning on t-PA and PAI-1 was observed in this model. The results indicated that: (1) Tissue t-PA activity in ischemia was significantly decreased than that in control (P < 0.01). t-PA activity was obviously increased in preconditioning group (P < 0.01 compared with ischemia group). (2) t-PA and PAI-1 mRNA expression in ischemia were higher than that in control, especially PAI-1 4.6 times higher than that in control), while PAI-1 expression lower in preconditioning rat. (3) In situ hybridization showed t-PA and PAI-1 were primarily expressed by endothelial cells in vessels of rat heart. These data suggested that abnormal expression of PAI-1 and t-PA was involved in AMI. This fibrinolytic depress was associated with high PAI-1 expression. Preconditioning may be effective to protect myocardium through decreasing PAI-1 mRNA expression.

Animals↗

PubMed1997

[Characterication of reference strains of L. interrogans in China by ISSP-PCR].

The gene polymorphism of the DNAs extracted from reference strains of L. interrogans in China was characterized by LSSP-PCR primered by G1 or G2, which were a pair of specific primers for L. interrogans. The fingerprinting produced by LSSP-PCR showed that serovar lai, serovar canicola, serovar pyrogens, serovar autumnalis, serovar australis, serovar linhai, serovar wolffi and serovar haemolytic have similar patterns, but serovar hebdomadis, serovar javanica, serovar ballum, serovar pomona, serovar spaidjin, serovar tarassov and serovar manahao I have different profiles. This result agreed with the classification of genetic species by Yasuda. The utilization of LSSP-PCR banding patterns in the identification of leptospries in blood samples also gained encouraging results. Compared with the routine methods in genetic species classification, LSSP-PCR has the advantages of rapidity, simplicity and low-cost. It appears to be a promising tool in studying such slowly growing bacteria as leptospires. Further exploration of LSSP-PCR in classification and identification of Leptospires is worthwhile.

DNA, Bacterial↗

PubMed1997

[Immunogenecity of expressed protein p68 from recombinant plasmid rpDJt in L. interrogans serovar lai].

There are two types of infection caused by pathogenic microorganisms, intracellular infection and intercellular infection. Infection of pathogenic leptospira is an intercellular infection. The immunological reaction of host to intercellular infection is unique. The potential immunogen of an expressed protein should meet three criteria: it can be degraded (by antigen-present cells in the host); it should have antigenic epitope which can be recognized by specific antibodies and have at least one epitope that can be recognized by an MHC II protein and T cell receptor. In this study we report the cloning of an L. interrogans protein in plasmid rpDJt and the immunogencity of the expressed protein derivative. A genomic library of L. interrogans serovar lai strain 017 was constructed with the plasmid vector pUC18. Recombinant plasmids, designated pDJH2 and pDJ8 were screened from the bank. EcoRI-inserted fragment of 1. 9 kb recombinant DNA of pDJH2 was ligated into T7 RNA polymerase/promoter vectors (pT7-7). Then they were transformed into E. coli JM109 (De3), one of subclones, designated rpDJt was achieved. SDS-PAGE showed that the molecular weights of expression proteins were 68 kd and 23 kd respectively, designated p68 and p23. Purifying and isolating p68 and p23, we separated them from SDS-Polyacrylamide gels by using Side-Strip method. After fragmenting and electroeluting, p68 and p23 were injected into guinea pigs and rabbits. An extremely strong immune response to p68 was obtained since an anti-p68 antibody response could be detected to a dilution 1:524,288 (guinea pigs) and 1:262,144 (rabbits) by ELISA while anti-P23 antibody being 1:1024 (the same to guinea pigs and rabbits). The results of improved MTT and conA 3HTdR transformation methods showed the activities and proliferation of Th-cells were increased in guinea pigs after p68 immunization (IL-6, 83.25 IU/ml, IL-2, 28.75 IU/ml; RPI, 2.04, SI, 65.62%) Thlymphocyte existed in two subclasses, the Th1- and Th2-cells. A major role of Th2-cells is to "help" B-cells differentiate, replicate, and secrete antibody. The properties of these interactions explain why p68 makes good antigen and p23 does not. The antigens responsible for eliciting the production of protective antibodies are not known; however, several outer membrane proteins on L. interrogans are candidates for vaccine. Our results suggest that expresion protein p68 from recombinants (rpDJt) may be a candidate for gene engineered subunit vaccine for Leptospirosis.

Animals↗

PubMed1997

[Analysis on speciems of serum and urine in 66 cases of early leptospirosis by PCR and biotin-AMPPD hybridization].

We used polymerase chain reaction (PCR) and Biotin-AMPPD hybridization to detect leptospiral DNA in blood and urine samples in 66 patients at the early stage of leptospirosis. The results showed that PCR and Biotin-AMPPD hybridization not only ruled out the non-specific PCR amplification and increased the reliability for clinical specineus of leptospirosis but also raised the detecting sensibility (from 71.3% to 86.1%). The positive rates of PCR resulted from serum and urine showed no statistical difference; therefore urine sample is worthy of application and dissemination for detecting leptospires at the early stage of leptospirosis. Urine sample is easier for one to collect, preserve and has less intervention. The primers G1, G2 are optimal opplication of PCR in epdemic areas in China.

Biotin↗

PubMed1997

[Bone histomorphometric changes in ovariectomized goat at different time courses].

Using histopatholoical method, we investigated the bone histomorphometric changes in ovariectomied goats at different time courses. Eight goats, female, aged one and a half years, were randomly divided into two groups, the control and the ovariectomy (OVX). Iliac crest biopsies were separately processed before ovariectomy and at 60 days, 120 days and 180 days after ovariectomy. The histomorphometric changes were observed. It was found that the bone structure in trabecular bone remained relatively constant in the control group throughout the whole study. In contrast, the trabecular quantity was slightly decreased and the trabeculae were disconnected in OVX at 60 days after ovariectomy. The bone structure was characterized by the thinning of the trabeculae, the further discontinuance and quantity loss of trabeculae, and the anlargement of marrow cavity at 120 days to 180 days after ovariectomy. Apparently, these bone structural changes manifested with typical osteopenia pathological changes. Our results may serve as a basis for the design of further studies using OVX goat as an animal model for postmenopausal osteoporosis.

Animals↗

PubMed1997

[Construction of genomic library of L. interrogans serovar lai using lambda gt11 as the vector and a study of recombiant plasmid pDL121].

A genomic library of L. interrogans serovar lai strain 017 has been constructed using lambda gt11 as the vector. DNA was partially digested by two blunt-end restriction enzymes, then methylated with EcoR I methylase; after EcoR I linker was added to the DNA, the linker-ended DNA was ligated to the dephosphorylated EcoR I digested lambda gt11 arms. The recombined DNA was packaged in vitro, and used to transduct E. coli Y1090 for amplification. There were 2.1 x 10(6) recombinant bacteriophages as recognized by their ability to form white plaques plated on Lac host in the presence of both IPTG and X-Ga1. A positive clone, designated lambda DL12, was screened with a rabbit anti-serum against L. interrogans serovar lai from the genomic library. The DNA from lambda DL12 was subcloned into plasmid pUC18. A recombinant (designated as pDL121) was obtained. SDS-PAGE analysis indicated that a 23 kd was expressed in E. coli JM 103 harboring pDL121. Western blotting analysis showed that a specific protein band molecular weight of 23 kd could be recognized by the rabbit antiserum against L. interrogans serovar lai strain 017.

Cloning, Molecular↗

PubMed1997

[The effects of hydroxyurea on cell-cycle distribution and the expression of human beta-globin gene in K 562 cells].

Although the hydroxyurea (HU) has been extensively studied, little is known of its molecular mechanism in controlling the expression of human globin gene and in modulating the progression of cell-cycle in K 562 cell. In the present study, the effect of hydroxyurea on proliferative kinetics of K 562 cells was examined by monitoring the number of cells during a period of 8 day's cell culture. Our results showed that there was a dose related decrease in cell growth when K562 cells were incubated with HU. Moreover, cell-cycle analysis demonstrated that HU had profound effect on cell-cycle distribution. In the case of the induced K 562 cells, there was an increased accumulation of cells in S phase and a decreased fraction of cells in G 1 and G 2 + M phase. Furthermore, HU could induce the expression of human beta-globin gene in the induced K 562 cells. Our results indicate that HU has a potential to inhibit the proliferation of K 562 cells and to stimulate the terminal differentiation of this cell.

Cell Cycle↗

PubMed1997

[Studies on nimodipine sustained-release tablet capable of floating on gastric fluid with prolonged gastric resident time].

Nimodipine was incorporated into poloxamer 188 solid dispersion before formulation, then mixed excipient and solid dispersion were directly compressed into nimodipine floating sustained-release tablet(NM-FSRT). Formulations were optimized using uniform design and variables affecting nimodipine release from matrix were studied. Preliminary in vivo evaluation was carried out in healthy volunteers. Results showed that the optimized formulation could remain floating on gastric fluid for over 10 hours. In vitro release(0.15-6 h) conformed to zero-order kinetics. Hydroxypropylmethylcellulose(HPMC) and polyethylene glycol 6000(PEG 6000) showed the biggest effect on in vitro drug release. Increasing HPMC content and decreasing PEG 6000 content led to decrease of nimodipine release in vitro. NM-FSRT did remain floating on gastric fluid with prolonged gastric resident time(GRT) of 5 hours under fed condition, while GRT was only 3 hours under fasted condition. GRT of nimodipine conventional tablet(NM-CT) under fed and fasted conditions was 3 and 2 hours, respectively. Relative bioavailability of NM-FSRT was 391.46% and MRT was over twice that of NM-CT. NM-FSRT appeared to have prolonged GRT and improved bioavailability.

Biological Availability↗

PubMed1997

[Comparative study on three different methods in typing hepatitis C virus].

The sea from 120 anti-HCV-positive patients were detected by three different methods to type HCV. In method A, PCR product of 5'-NC region was cut by restriction endonuclease. In method B, PCR with HCV core region type-specific primers was used. In method C, EIA based on HCV genotype I, II (serotype 1) and genotype III, IV (serotype 2) synthetic peptides was used to detect type-specific antibodies. It was showed that HCV genotypes were successfully identified in 96(80%) patients both by method A and method B, with HCV-II 86(89.6%), HCV-III 8(8.3%), HCV-II/III coinfection 2(2.1%). The results of these two methods were completely agreeable. HCV type-specific antibodies were detected in 78(65%) cases by method C, with serotype 1 68(87.2%), serotype 2 6(7.7%), serotype 1 plus 2 positive 4(5.1%). The comparative estimation of 66 patients who were positive for all the three methods showed a remarkable concordance (64/66, 97.0%). Our study demonstrated that the results of different HCV-typing methods mentioned above were fairly consistent and reliable. The abvantages, disadvantages and practical applicable scope of these methods were discussed in the paper.

Genotype↗

PubMed1997

[Serum G-CSF levels in patients with chronic aplastic anemia].

OBJECTIVE: To explore the pathogenesis of aplastic anemia. METHODS: The spleen cells of BALB/c miceimmunized with rhG-CSF were fused with myeloma cell line SP2/0. Three murine hybridomas producing monoclonal antibody (McAb) against rhG-CSF were obtained. Serum levels of G-CSF in 54 cases of chronic aplastic anemia (CAA) were detected by ELISA method. RESULTS: Serum G-CSF levels in 70.4% (38 of 54 cases) of the CAA patients were increased (272.76 +/- 58.39ng/L). There was a negative correlation between blood neutrophil counts and serum G-CSF levels (r = -0.535, P<0.01). CFU-GM were detected in 12 cases of CAA, and all was decreased (17.92 +/- 10.28/2 x 10(5) nucleated cell). Serum G-CSF levels in almost 30% (12 of 54 cases) of the CAA patients were not increased. CONCLUSION: The hematopoietic progenitor cells of CAA patients were impaired, and some CAA could be treated with rhG-CSF and immunosuppressive agents.

Adult↗

PubMed1997

[In vitro study on the effects of the novel retinoids on the proliferation and differentiation of normal and leukemic cells].

OBJECTIVE: To evaluate the prospect for clinical use of four novel retinoid compounds (retinoid 1, retinoid 2, retinoid 3 and retinoid 4), which were different structurally from all-trans retinoic acid. METHODS: The effects of the four retinoids on the differentiation and clonal proliferation of NB4 cells and fresh acute promyelocytic leukemia (APL) cells and on the proliferation of normal hematopoietic cells were studied. Cell morphological examination,nitro tetrazolium blue reduction test, cell cycle dynamics, and colony formation assay were used in the study. RESULTS: Novel retinoids induced differentiation of NB4 and fresh APL cells, and markedly inhibited CFU-L growth of NB4 and fresh APL cells. The activity related to their chemical structures and retinoid 2 was more active. The novel retinoids enhanced the growth of CFU-GM, CFU-E and CFU--Meg of normal bone marrow cells. CONCLUSION: These novel retinoids, especially retinoid 2, may regulate the proliferation and differentiation of normal hematopoiesis, induce APL cell differentiation and maturation, and are worthy of further study for clinical use.

Cell Differentiation↗

PubMed1997

Expression in Escherichia coli and purification of human thrombopoietin.

Human thrombopoietin (TPO) has been successfully overexpressed in Escherichia coli, with an expression level of about 12% of total cellular protein. The full-length TPO gene was subcloned into the prokaryotic expression vector pKK233-2 under the control of the inducible tac promoter. The recombinant protein was produced mainly in the form of inclusion body. By efficient renaturation and one-step purification, the recombinant protein was purified to homogeneity. The specific activity and yield of recombinant TPO can reach 2 x 10(4) units/mg and 2 mg/g of wet E. coli cells respectively.

Chromatography, Liquid↗

PubMed1997

Evaluation of the antiinflammatory activity of a dual cyclooxygenase-2 selective/5-lipoxygenase inhibitor, RWJ 63556, in a canine model of inflammation.

Sterile perforated polyethylene spheres (wiffle golf balls) were implanted s.c. in beagle dogs. A local inflammatory reaction was elicited within the spheres by injecting carrageenan. Changes in leukocyte count, prostaglandin E2, thromboxane B2 and leukotriene B4 levels were monitored in fluid samples collected over a 24-hr period. Blood samples were also collected at various time points and analyzed for prostaglandin E2 and leukotriene B4 production after ex vivo calcium ionophore treatment. Effects of standard antiinflammatory agents (aspirin, indomethacin, dexamethasone, tenidap and zileuton) and newer cyclooxygenase-2 (COX-2) selective agents (nimesulide, nabumetone and SC-58125) were determined after oral administration. Ex vivo inhibition of cyclooxygenase product synthesis (prostaglandin E2, thromboxane B2) in whole blood was used as an indicator of activity for the constitutive COX-1 isoform, although inhibition of the synthesis of these mediators in the chamber exudate during an inflammatory process is believed to represent COX-2 inhibition. Treatment effects on leukotriene B4 production were also determined both ex vivo in whole blood and in the fluid. All of the compounds tested, except aspirin, inhibited leukocyte infiltration into the fluid exudate. Inhibitors that exert their effects on both isozymes of cyclooxygenase attenuate production of cyclooxygenase metabolites in both the inflammatory exudate and in peripheral blood ex vivo, although COX-2 selective inhibitors only demonstrated activity in the exudate. A 5-lipoxygenase inhibitor (zileuton), a corticosteroid (dexamethasone) and a dual COX-2 selective/5-lipoxygenase inhibitor (RWJ 63556) had similar profiles in that they all inhibited cell infiltration and eicosanoid production in the fluid and also attenuated leukotriene B4 production in both the fluid and blood.

Animals↗

PubMed1997

Disease expression in X-linked retinitis pigmentosa caused by a putative null mutation in the RPGR gene.

PURPOSE: To determine the disease expression in X-linked retinitis pigmentosa (XLRP) caused by a putative null mutation in the RPGR (retinitis pigmentosa GTPase regulator) gene. METHODS: In a family with XLRP, haplotype analysis was performed with polymorphic microsatellite markers from the Xp chromosomal region, and genomic polymerase chain reaction sequencing was used to identify sequence variations in the RPGR gene. Hemizygotes and heterozygotes were evaluated clinically and with visual function tests. Optical coherence tomography (OCT) was performed on heterozygotes. Postmortem donor retinas from a heterozygote were examined by microscopy and immunocytochemistry. RESULTS: X-linked inheritance was confirmed by haplotype analysis using Xp markers. Sequence analysis of the RPGR gene identified a single base pair change, a G-->T transversion, that converts codon 52 GGA (Gly) to TGA (stop codon); the mutation segregates with the disease. A hemizygote in the third decade of life had barely measurable rod function and severely impaired cone function that diminished further over a 7-year interval. Heterozygotes varied in degree of disease expression from mild to severe. Perimetry showed loci with normal rod and cone sensitivity interspersed with loci having either equal rod and cone dysfunction or rod > cone dysfunction. Electroretinographic photoreceptor responses had equal reductions in rod and cone maximal amplitude. OCT cross sectional reflectance images of retinal regions with severe dysfunction showed reduced thickness of the retina and retinal pigment epithelium-choriocapillaris (RPE-CC) complex and increased reflections posteriorly. Regions with mild dysfunction showed similar OCT findings but with preserved retinal thickness. Retinal histopathology in a heterozygote revealed loss of photoreceptors throughout, with retention of only a few islands of cones with tiny or absent outer segments and rods lacking outer segments. CONCLUSIONS: This RPGR gene mutation, in its mildest expression in heterozygotes, causes a relatively equal disturbance of rod and cone photoreceptor function. Detectable structural change by OCT at the level of the RPE-CC can be present in patches of retina with minimal functional disturbance. More advanced disease stages in heterozygotes show greater rod than cone dysfunction, and the end stage in hemizygotes and heterozygotes is that of typical RP, with only barely detectable cone function from residual cones in a thinned retina with abnormal RPE and choriocapillaris.

Adult↗