Biomedical subjects

B Kang

Publications and source records attributed to B Kang.

At least 19 recordsLinked to original sources

PubMed2006

Prevalence and genotyping of hepatitis E virus in swine population in Korea between 1995 and 2004: a retrospective study.

Hepatitis E virus (HEV) infections have been reported in pigs throughout the world but have only recently been recorded in Korean pigs. The aim of this study was to investigate whether HEV was present in archived porcine hepatic tissues collected between 1995 and 2004 using RT-PCR and immunohistochemistry and, if so, to determine the genotype of the isolates. Swine HEV was identified in the liver tissue of 42 pigs of 388 submissions (four pigs every year on average). The isolates showed genetic homology with swine and human HEV isolates identified in the United States and Japan (92.5-97%) and phylogenetic tree analysis indicated they belonged to genotype III. The study indicates that HEV is not a newly emerging virus in Korean pigs, but a pathogen that has existed in the country since at least 1995.

Animals↗

PubMed2006

Expression of programmed cell death 5 gene involves in regulation of apoptosis in gastric tumor cells.

The protein of programmed cell death 5 (PDCD5) is believed to participate in regulation of apoptosis. Although PDCD5 is reducibly expressed in various human tumors, it is not clear which expression level of PDCD5 is in gastric cancer (GC). In this study, we have systematically employed the approaches of RT-PCR, Real- time PCR, Immunohistochemistry (IHC), Immunofluorescence staining (IFS) and Western blot to determine the PDCD5 expression in GC cells and primary tumors, at mRNA and protein level, respectively. Our data revealed that the positive rate of PDCD5 expression in the gastric tumor tissues was significantly less than that of the normal tissues (14 out of 102 vs 36 out of 51), whereas, the decreased expression of PDCD5 protein was well correlated with the up-regulated expression of Bcl-2 in these tissues, and the up-regulated expression and nuclear translocation of PDCD5 protein were verified in the apoptotic GC cells induced by Diallyl trisulfide (DATS). Furthermore, the survival curve has suggested that the more PDCD5 expressions were found in the patients, the longer the survival periods were. Therefore, our observations lay down a reasonable postulation that PDCD5 may play a key role to regulate the apoptotic processes in the GC cells and gastric tumors.

Apoptosis↗

PubMed2005

Magnetic microstructures and their dynamics studied by X-ray microscopy.

Full-field soft X-ray microscopy in combination with X-ray magnetic circular dichroism as contrast mechanism is a powerful technique to image with elemental specificity magnetic nanostructures and multilayered thin films at high lateral resolution down to 15nm by using Fresnel zone plates as X-ray optical elements. Magnetization reversal phenomena on a microscopic level are studied by recording the images in varying external magnetic fields. Local spin dynamics at a time resolution below 100ps can be addressed by engaging a stroboscopic pump-and-probe scheme taking into account the time pattern of synchrotron storage rings. Characteristic features of magnetic soft X-ray microscopy are reviewed and an outlook into future perspectives with regard to increased lateral and temporal resolution is given.

Journal Article↗

PubMed2004

Repeat induced abortions and contraceptive practices among unmarried young women seeking an abortion in China.

OBJECTIVE: To determine the rates of repeated abortion and contraceptive use among unmarried young women seeking an abortion in China. METHODS: We used an anonymous self-administered questionnaire at abortion clinics in Beijing, Changsha, and Dalian from January to September 2000. RESULTS: Of 4547 unmarried young women seeking an abortion, 33.0% reported having had one previous induced abortion. Of those who had had more than one abortion, only 29.7% used a contraceptive method at their first sexual intercourse after the procedure; and of the 446 women who chose contraception, 41.3% used the traditional methods of withdrawal or rhythm. Although 65.0% of the young women had used condoms at least once, only 9.6% did so consistently and correctly; 47.7% of the current pregnancies were associated with nonuse of any contraceptive, and 52.3% were related to contraceptive failure. CONCLUSION: The rate of unmarried young women seeking repeated abortions was high in China on 2000. The rate of consistent condom use was low, and the rate of contraceptive failure was higher.

Abortion, Induced↗

PubMed2002

A gene therapy for cancer based on the angiogenesis inhibitor, vasostatin.

The growth and persistence of solid tumors and their metastasis are angiogenesis-dependent. Vasostatin, the N-terminal domain of calreticulin inclusive of amino acids 1-180, is a potent angiogenesis inhibitor. To investigate whether intramuscular administration of vasostatin gene has the antitumor activity in mouse tumor models, we constructed a plasmid DNA encoding vasostatin and a control vector. Production and secretion of vasostatin protein by COS cells transfected with the plasmid DNA encoding vasostatin (pSecTag2B-vaso) were confirmed by Western blot analysis and ELISA. Conditioned medium from vasostatin-transfected COS cells apparently inhibited human umbilical vein endothelial cell (HUVEC) and mouse endothelial cell (SVEC4-10) proliferation, compared with conditioned medium from the COS cells transfected with control vector or non-transfected cells. Treatment with pSecTag2B-vaso twice weekly for 4 weeks resulted in the inhibition of tumor growth and the prolongation of the survival of tumor-bearing mice. The sustained high level of vasostatin protein in serum could be identified in ELISA. Angiogenesis was apparently inhibited in tumor by immunohistochemical analysis. Angiogenesis was also inhibited in the chicken embryo CAM assay and mouse corneal micropocket assay. The increased apoptotic cells were found within the tumor tissues from the mice treated with plasmid DNA encoding vasostatin. Taken together, the data in the present study indicate that the cancer gene therapy by the intramuscular delivery of plasmid DNA encoding vasostatin, is effective in the inhibition of the systemic angiogenesis and tumor growth in murine models. The present findings also provide further evidence of the anti-tumor effects of the vasostatin, and may be of importance for the further exploration of the application of this molecule in the treatment of cancer.

Angiogenesis Inhibitors↗

PubMed2001

Immunogene therapy of tumors with vaccine based on Xenopus homologous vascular endothelial growth factor as a model antigen.

Overcoming immune tolerance of the growth factors associated with tumor growth should be a useful approach to cancer therapy by active immunity. We used vascular endothelial growth factor (VEGF) as a model antigen to explore the feasibility of the immunogene tumor therapy with a vaccine based on a single xenogeneic homologous gene, targeting the growth factors associated with angiogenesis. To test this concept, we constructed a plasmid DNA encoding Xenopus homologous VEGF (XVEGF-p) and control vectors. We found that immunogene tumor therapy with a vaccine based on XVEGF was effective at both protective and therapeutic antitumor immunity in several tumor models in mice. VEGF-specific autoantibodies in sera of mice immunized with XVEGF-p could be found in Western blotting analysis and ELISA assay. The purified immunoglobulins were effective at the inhibition of VEGF-mediated endothelial cell proliferation in vitro, and at antitumor activity and the inhibition of angiogenesis by adoptive transfer in vivo. The elevation of VEGF in the sera of the tumor-bearing mice could be abrogated with XVEGF-p immunization. The antitumor activity and production of VEGF-specific autoantibodies, significantly elevated IgG1 and IgG2b, could be abrogated by the depletion of CD4(+) T lymphocytes. The observations may provide a vaccine strategy for cancer therapy through the induction of autoimmunity against the growth factors associated with tumor growth in a cross reaction with single xenogeneic homologous gene and may be of importance in the further exploration of the applications of other xenogeneic homologous genes identified in human and other animal genome sequence projects in cancer therapy.

Animals↗

PubMed2001

Intrathecal administration of endothelin-1 receptor antagonist ameliorates autoimmune encephalomyelitis in Lewis rats.

The role of endothelin-1 (ET-1) in the development of experimental autoimmune encephalomyelitis (EAE) was studied by the blocking the action of ET-1 with a receptor antagonist, BQ-123. Intrathecal administration of BQ-123 significantly ameliorated EAE progression at the peak stage of EAE (p<0.05). By immunohistochemistry, ED-1-positive macrophages in EAE lesions were identified as major producers of ET-1, whereas the immunoreactivity of ET-1 on brain cells, such as astrocytes, was dramatically increased in accordance with the progression of EAE. This study points to a putative pro-1nflammatory role for ET-1 in the pathogenesis of EAE. One possible application for the ET-1 receptor antagonist might be helpful in the therapy of autoimmune neurological disorders.

Animals↗

PubMed2001

Inhibition of nicotinic acetylcholine receptors and calcium channels by clozapine in bovine adrenal chromaffin cells.

The effects of clozapine on the activities of nicotinic acetylcholine receptors (nAChRs) and voltage-sensitive calcium channels (VSCCs) were investigated and compared with those of chlorpromazine (CPZ) in bovine adrenal chromaffin cells. [(3)H]Norepinephrine ([(3)H]NE) secretion induced by activation of nAChRs was inhibited by clozapine and CPZ with half-maximal inhibitory concentrations (IC(50)) of 10.4 +/- 1.1 and 3.9 +/- 0.2 microM, respectively. Both cytosolic calcium increase and inward current in the absence of extracellular calcium induced by nicotinic stimulation were also inhibited by clozapine and CPZ, but the greater inhibition was achieved by CPZ. In addition, [(3)H]nicotine binding to chromaffin cells was inhibited by clozapine and CPZ with IC(50) values of approximately 19 and 2 microM, respectively. On the other hand, [(3)H]NE secretion induced by high K(+) was inhibited by clozapine and CPZ with similar IC(50) values of 15.5 +/- 3.8 and 17.1 +/- 3.9 microM, respectively. Our results suggest that clozapine, as well as CPZ, inhibits nAChRs and VSCCs, thereby causing inhibition of catecholamine secretion, and that clozapine is much less potent than CPZ in inhibiting nAChRs.

Adrenal Glands↗

PubMed2001

p38beta MAP kinase protects rat mesangial cells from TNF-alpha-induced apoptosis.

p38 MAP kinases (p38) and c-Jun N-terminal protein kinases (JNK) have been associated with TNF-alpha-induced apoptosis. However, recent studies indicate that an early but brief activation of JNK and/or p38 may actually protect some cells from TNF-alpha-induced apoptosis. Whether the activation of JNK and p38 provides a pro- or anti-apoptotic signal for TNF-alpha has been controversial. In this study, we investigated the role of p38 in the regulation of TNF-alpha cytotoxicity in rat mesangial cells. Treatment of the cells with TNF-alpha alone had little effect on their viability, but they became very sensitive to apoptosis when treated with TNF-alpha in the presence of the p38 inhibitor SB 203580. These results suggested that the p38 pathway is critical for mesangial cells to survive the toxic effect of TNF-alpha. Using adenovirus-mediated gene transfer technique, we further demonstrated that p38beta, but not p38alpha, is essential to protect the cells from TNF-alpha toxicity. It has been speculated that there is a synergetic interaction between the p38 and the nuclear factor-kappaB (NF-kappaB) pathways in protecting certain cells from apoptosis. However, expression of neither p38beta nor its dominant negative mutant in mesangial cells interfered with TNF-alpha-induced translocation of NF-kappaB, the initial step of NF-kappaB activation. While it is unclear whether p38beta regulates NF-kappaB transcription activity at other steps, it is apparent that p38beta does not affect TNF-alpha-induced NF-kappaB activation at the stage of nuclear translocation.

Adenoviridae↗

PubMed2001

Ultrasonographic diagnosis of bone tumor of the knee and its clinical implication.

In order to evaluate the value of the ultrasonography in the diagnosis of tumor of the knee and its clinical implication, 67 patients with clinically suspected bone tumor of the knee were examined by ultrasound. The ultrasonographic characteristics of different bone tumors were studied and compared with the results of pathologic characters after operation. Ultrasonography can readily visualize the bony destruction and the pathologic change of the periosteum and the soft tissue related to bone tumor. Fifty-two cases of malignant bone tumors and 15 cases of giant cell tumors were diagnosed by ultrasonography. Pathologically, there were 54 cases of malignant bone tumor and 13 cases of giant cell tumor. It was concluded that ultrasonographic examination might be a useful method for the diagnoses of bone tumor of the knee and play an important role in guiding needle biopsy and electing operative method and approach.

Adolescent↗

PubMed2001

Effect of omeprazole-induced achlorhydria on trefoil peptide expression in the rat stomach.

BACKGROUND: Omeprazole is an inhibitor of the H+K+ ATPase of the gastric parietal cell, which is used clinically to suppress gastric acid secretion. It has also been found to inhibit gastric mucin production; however, its effects on the synthesis and secretion of the trefoil peptides, which are also expressed by mucus cells, and which play a key role in cytoprotection and epithelial repair, are unknown. METHODS: Rats (n=8) were given either omeprazole (30 mg/kg per day; p.o.) or inert carrier for 1 week, and the effects on synthesis and peptide expression of the gastric trefoil peptides, TFF1/pS2 and TFF2/SP, were compared. RESULTS: As expected, omeprazole treatment abolished H+ ion production with a mean gastric juice pH of 7.2 compared with 2.4 for controls. The omeprazole group had elevated total protein levels of 35-fold and TFF1/pS2 peptide levels elevated fourfold, respectively, but not TFF2/SP peptide in gastric juice, suggesting that the increased pH reduced the viscosity of adherent mucus, thereby increasing gastric juice concentrations by dissolution of adherent TFF1/pS2 and increased secretion. Concomitant with increased TFF1/pS2 secretion was a fall in predominantly antral mucosal trefoil peptide concentrations. In contrast to trefoil secretory rates, the steady-state synthesis of both TFF1/pS2 and TFF2/SP was unchanged after omeprazole treatment, implying both a large cellular pool of processed peptide and rapid secretion. CONCLUSION: The increase in the concentration of TFF1/pS2 in gastric secretions during chronic omeprazole-induced achlorhydria may be important in preventing tissue injury and promoting repair in response to an increased luminal bacterial population.

Achlorhydria↗

PubMed2001

Validation of finite element analysis in dental ceramics research.

STATEMENT OF PROBLEM: In vitro dental materials strength testing of ceramic restorations primarily has involved mechanical evaluations of simplified models. The finite element method (FEM) provides a mathematic analysis to predict strength values, but neither methodology is without the potential for errors. PURPOSE: The purpose of this study was to demonstrate the advantages of combining mechanical testing results and FEM data to determine the strengths of a layered ceramic beam when the layered materials and positions are varied. MATERIAL AND METHODS: Eight finite element 5 x 20 x 1-mm layered beams were modeled. Four of the modeled beams were of the same layered arrangements as physical specimens from a previously published study. The remaining 4 modeled beams provided intermediate layered arrangements not evaluated in the earlier study. A force in newtons was applied in the center of the top layer of each beam until fracture. finite element analysis was performed, and the data were compared with mechanical strength test results from the earlier study. RESULTS: The FEM data of the 8 models demonstrated a linear decrease in load-bearing capacity as the layer thickness of the core material decreased and the layer thickness of the veneer material increased. The progressively decreasing values for the FEM beams were 170, 144, 140, 134, 72, 43, 34, and 27 N. The mean load-bearing capacities of 3 of the 4 mechanically tested beams compared favorably with the FEM data. The strength of the fourth mechanically tested beam, a veneer/core layered arrangement, was 110 N, which was lower than the corresponding FEM value (140 N). The 110 N value fell outside the decreasing linear progression for load, indicating that the FEM data were more accurate and reliable than the mechanical data. CONCLUSION: No one perfect method exists for testing the strength of dental materials. The best approach is to use the results from both mechanical testing and finite element analysis, which together may provide more reliable and valid data than either method alone.

Aluminum Oxide↗

PubMed2001

Development of new T-vectors containing the luciferase gene. Easy application for direct cloning of a promoter DNA.

For promoter analyses of genes, it is usually necessary to amplify promoter DNA fragments by polymerase chain reaction (PCR) and clone them into a plasmid containing a reporter gene. In the present study we developed a novel plasmid, pGL2-X, which was constructed through a simple procedure of cloning an XcmI cassette from the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene into the multicloning site of pGL2-Basic (Promega) pGL2-X was then converted by XcmI digestion into a T-vector which was named pGL2-T. Unfortunately, however, the firefly luciferase gene in pGL2-Basic contains one XcmI restriction site and therefore one base within the recognition site was silent-mutated. The cloning efficiency of the pGL2-T vector was approximately 63% when tested with a PCR product amplified from a promoter region (-501(-)+24) of the murine acetylcholine receptor delta subunit (AchR delta) gene. In C2C12 muscle cells transiently transfected with pGL2-T containing the AchR delta promoter, transcription of the silent-mutated luciferase gene increased 2.2-fold by neuregulin (EGF domain of heregulin beta 1; 100 ng/mL), a known stimulator of AchR delta expression. This result suggested that the pGL2-T vector was biologically functional. Thus, the present study provides an easy method to construct a variety of T-vectors containing different reporter genes.

Base Sequence↗

PubMed2001

[Case-control study on sexual coercion and related risk factors in China].

OBJECTIVE: To find out the determinants of sexual coercion among adolescent abortion seekers in China. METHODS: Case-control study was adopted. Women seeking for abortion and ever having experienced sexual coercion were taken as case group and those who had never experienced sexual coercion as control group. Case-control study was carried out in 11 large hospitals in Beijing city from January 2000 to April 2000. RESULTS: The number of subjects in case group was 512, comparing to 517 in the control group. The mean age of subjects was 20.25 years with monthly income 881.2 RMB Yuan. The difference between case group and control group in income, occupation and age showed no statistical significance. The results of the study indicated that the factors which were more likely to be related to sexual coercion include lower educational level (chi(2) = 15.27, P < 0.01, OR: 1.71), not living with parents (chi(2) = 10.18, P < 0.01, OR: 1.50), mobile nature (chi(2) = 20.60, P < 0.01, OR: 1.78), experienced battery by partner (chi(2) = 6.79, P < 0.01, OR: 2.72), abused by her partner (chi(2) = 4.22, P < 0.05, OR: 1.71) multi-partners (chi(2) = 19.08, P < 0.01, OR: 2.17), sex after being drunk (chi(2) = 34.22, P < 0.01, OR: 5.04), and larger gaps of in age between male and female partners (chi(2) = 11.04, P < 0.01, OR: 2.17). CONCLUSION: Factors as, poor-educated, not living with parents, floating population, multi-partners, the inequality between male and female were more likely to increase the risk of sexual coercion.

Adult↗

PubMed2000

Prolonged exposure to hyperbaric oxygen induces neuronal damage in primary rat cortical cultures.

While seizure attack is one of the serious complications during the hyperbaric oxygen (HBO) therapy, there is still no direct evidence showing that HBO can induce neuronal damage in the brain. The objective of this study was first to investigate whether HBO would lead to neurotoxicity in the primary rat cortical culture. Second, since alterations in neurotransmitters have been suggested in the pathophysiology of central nervous system (CNS) oxygen toxicity, the protective effects of the N-methyl-D-aspartate (NMDA) receptor antagonism and nitric oxide (NO) synthase inhibition on the HBO-induced neuronal damage were examined. The results showed that HBO exposure to 6 atmosphere absolute pressure (ATA) for 30, 60, and 90 min increased the lactate dehydrogenase (LDH) activity in the culture medium in a time-dependent manner. Accordingly, the cell survival, measured by the 3,(4,5-dimethyl-2-thiazolyl)2, 5-diphenyl-tetrazolium bromide (MTT) assay, was decreased after HBO exposure. Pretreatment with the NMDA antagonist MK-801 protected the cells against the HBO-induced damage. The protective effect was also noted in the cells pretreated with L-N(G)-nitro-arginine methyl ester, an NO synthase inhibitor. Thus, our results suggest that activation of NMDA receptors and production of NO play a role in the neurotoxicity produced by hyperbaric oxygen exposure.

Animals↗

PubMed2000

Virulent strains of Helicobacter pylori demonstrate delayed phagocytosis and stimulate homotypic phagosome fusion in macrophages.

Helicobacter pylori colonizes the gastric epithelium of approximately 50% of the world's population and plays a causative role in the development of gastric and duodenal ulcers. H. pylori is phagocytosed by mononuclear phagocytes, but the internalized bacteria are not killed and the reasons for this host defense defect are unclear. We now show using immunofluorescence and electron microscopy that H. pylori employs an unusual mechanism to avoid phagocytic killing: delayed entry followed by homotypic phagosome fusion. Unopsonized type I H. pylori bound readily to macrophages and were internalized into actin-rich phagosomes after a lag of approximately 4 min. Although early (10 min) phagosomes contained single bacilli, H. pylori phagosomes coalesced over the next approximately 2 h. The resulting "megasomes" contained multiple viable organisms and were stable for 24 h. Phagosome-phagosome fusion required bacterial protein synthesis and intact host microtubules, and both chloramphenicol and nocodazole increased killing of intracellular H. pylori. Type II strains of H. pylori are less virulent and lack the cag pathogenicity island. In contrast to type I strains, type II H. pylori were rapidly ingested and killed by macrophages and did not stimulate megasome formation. Collectively, our data suggest that megasome formation is an important feature of H. pylori pathogenesis.

Animals↗

PubMed2000

Immunotherapy of tumors with xenogeneic endothelial cells as a vaccine.

The breaking of immune tolerance against autologous angiogenic endothelial cells should be a useful approach for cancer therapy. Here we show that immunotherapy of tumors using fixed xenogeneic whole endothelial cells as a vaccine was effective in affording protection from tumor growth, inducing regression of established tumors and prolonging survival of tumor-bearing mice. Furthermore, autoreactive immunity targeting to microvessels in solid tumors was induced and was probably responsible for the anti-tumor activity. These observations may provide a new vaccine strategy for cancer therapy through the induction of an autoimmune response against the tumor endothelium in a cross-reaction.

Amino Acid Sequence↗

PubMed1999

g-matrix based on configuration interaction and Stone's perturbation theory

Stone's formula, which has usually been applied to the calculation of the g-matrix, is based on a single-configuration treatment. Here a limited configuration interaction is included to obtain the expressions of the principal g values for an orbitally nondegenerate molecule with spin S = 12. Copyright 1999 Academic Press.

Journal Article↗