Biomedical subjects

H R Park

Publications and source records attributed to H R Park.

At least 19 recordsLinked to original sources

PubMed2006

Polyphenol (-)-epigallocatechin gallate protection from ischemia/reperfusion-induced renal injury in normotensive and hypertensive rats.

INTRODUCTION: The effect of epigallocatechin gallate (EGCG) in an in vivo renal model of ischemia with reperfusion (I/R) was compared between normotensive (WKR) and hypertensive (SHR) rats. METHODS: WKR (groups I, II, III) and SHR groups (groups IV, V, VI) were divided into three types. Groups I and IV were sham-operated animals; groups II and V were subjected to 45 minutes of renal I/R; and groups III and VI received 10 mg/kg EGCG intravenously at the time of reperfusion. Three days after renal I/R, we compared renal function markers, malondialdehyde (MDA), and histologic changes. RESULTS: Following renal I/R, levels of blood urea nitrogen (BUN) and serum creatinine (sCr) were increased and serum creatinine clearance (CrCl) decreased in group V compared to group II (P < .001). Those receiving EGCG treatment (groups III and VI) had decreased BUN and sCr compared to non-EGCG I/R groups (P < .001), but not surprisingly, higher than sham groups. CrCl was lowest in the SHR groups. The MDA was significantly decreased after EGCG treatment (P = .028 in group III, P = .002 in group VI). Following renal I/R, tissue necrosis was more severe among SHR (P < .001). However, the ratio of regeneration to damage significantly increased in SHR after EGCG treatment. CONCLUSIONS: The reperfusion injury was greater among SHR compared with WKR in terms of renal function, lipid peroxidation, and tissue damage. EGCG treatment significantly ameliorated renal impairment and promoted tissue regeneration following renal I/R.

Animals↗

PubMed2006

Placenta hominis protects osteoporosis in ovariectomized rats.

In China, Japan, and Korea, placenta hominis extracts (PHEs) are used clinically for the treatment of osteoporosis. The anti-osteoporotic effect of PHEs was studied. The trabecular bone area and thickness in OVX rats decreased by 50% from those in sham-operated rats; these decreases were completely inhibited by administration of PHEs for 7 weeks. Osteoclast numbers and the osteoblast surface were enhanced in OVX rats, but PHEs had no effect on these phenomena. Serum phosphorus and alkaline phosphatase in OVX rats increased compared to those in sham-operated rats, but the increases were not affected by the administration of PHEs. Thyroxine (T4) level was stimulated in OVX rats. The extracts inhibited the T4 level in the OVX rats. These results strongly suggest that PHEs be effective in preventing the development of bone loss induced by OVX in rats.

Animals↗

PubMed2005

Carbon monoxide and nitric oxide protect against tumor necrosis factor-alpha-induced apoptosis in osteoblasts: HO-1 is necessary to mediate the protection.

BACKGROUND: Carbon monoxide (CO) and nitric oxide (NO) each have unique roles for various inflammatory states, including inflammatory bone resorption. Although it is known that NO can induce the expression of the cytoprotective enzyme HO-1, there is no information as to whether the protective effect of CO requires NO production or whether CO must induce the expression of HO-1 to exert its functional effects. METHODS: Murine osteoblast cells, MC3T3E1 osteoblasts, were cultured for CO and NO-associated HO-1 experiments and were transfected with pcDNA 3, pcDNA 3-HO-1, control siRNA or HO-1 siRNA using Nucleofector. For cell death measurement, MTT and annexin V assays were used. We performed Western blotting to check the expressions of HO-1 and iNOs and measured the HO-1 enzyme activity. We also measured the amounts of nitrite and nitrate using Griess reagents. RESULTS: The increased expression of HO-1 is required for the protective effect of NO and a single treatment of CO can increase the expression of HO-1, and this is also important for the protective effect of CO in MC3T3E1 osteoblasts. CO as well as NO attenuates the TNF-alpha-induced apoptosis in osteoblasts. The anti-apoptotic effect of CO or NO is not mediated by cGMP, and CO has no effect on the release of NO. The inhibition of HO-1 with using the HO-1 inhibitor ZnPP or HO-1 siRNA resulted in a striking increase of apoptosis in the CO/TNF-alpha-treated cells. Furthermore, HO-1 overexpression showed resistance against the TNF-alpha-induced cytotoxicity in the MC3T3E1 osteoblasts. CONCLUSIONS: There is a need for HO-1 expression to mediate the protection provided by exogenous CO or NO in osteoblasts.

3T3 Cells↗

PubMed2004

Yuk-Hap-Tang induces apoptosis by intervening mn-SOD in human cervical carcinoma HeLa cells.

Yuk-Hap-Tang (YHT) induces cell death in human cervical carcinoma HeLa cells. Caspase-3, -6 and -9 were markedly activated in HeLa cells treated with YHT. The preferred substrate for caspase-3 cysteine protease, PARP, was cleaved to its 85-kDa cleavage product. YHT increased the amount of the anti-apoptotic protein, Bcl-2, and the pro-apoptotic protein, Bax. Although p53 has been reported to accumulate in cancer cells in response to anticancer agents, the p53 expression level was not changed in HeLa cells treated with YHT. Manganese (Mn)-TBAP, a mitochondria-specific SOD mimetic agent and NAC/GSH (N-acetyl cysteine/ reduced glutathione) reduced the YHT-induced cytotoxicity and decreased the number of the YHT-induced apoptotic cells. Furthermore, YHT reduced the expression of Mn-SOD protein and its activity in HeLa cells. The data demonstrate that YHT induces the apoptosis of human cervical carcinoma HeLa cells by intervening Mn-SOD.

Antioxidants↗

PubMed2003

Association of maspin expression with the high histological grade and lymphocyte-rich stroma in early-stage breast cancer.

AIMS: Maspin is a recently described member of the serpin family or protease inhibitors that is known to be a tumour suppressor gene product. Loss of maspin expression has been found in most breast cancer cases and is correlated with cell motility and tumour invasiveness. However, its precise role in human breast cancer remains to be discovered. We aimed to evaluate the role of maspin in early-stage breast cancer. METHODS AND RESULTS: We analysed the expression of maspin in 192 stage I and II primary breast cancers by immunohistochemistry. Of these cases, 34.4% showed maspin expression. Maspin expression was more frequently found in invasive ductal carcinoma (36.4%) than in invasive lobular carcinoma (7.1%). High maspin expression was demonstrated in breast cancers showing high histological grade or lymphocyte-rich stroma (P < 0.05). Maspin expression was not associated with overall and disease-free survival rate of breast cancer. CONCLUSIONS: The results indicate that different biological mechanisms may be responsible for maspin expression in histologically distinct types of breast cancer. Our survey suggests that maspin expression in breast cancer might have a compensatory role rather than prognostic one.

Adenocarcinoma↗

PubMed2003

Improved production of teicoplanin using adsorbent resin in fermentations.

AIMS: To use adsorbent resins in fermentations to eliminate toxic effects on growth, reduce feedback repression of production and assist in recovery of teicoplanin. METHODS AND RESULTS: An adsorbent resin was added to the culture broth for the adsorption of teicoplanin. Amberlite XAD-16, Diaion HP-20, charcoal and silica gel were investigated as adsorbent resins. The adsorbed teicoplanin was extracted from the resin by 80% methanol after fermentation. Antibiotic activity was quantified by the disc-agar diffusion assay against Bacillus substilis, and qualitative evaluations were based on HPLC using YMC-Pack ODS-A column. Diaion HP-20 was the most effective adsorbent resin when added at a concentration of 5% (w/v) in the inoculation stage. CONCLUSIONS: Addition of Diaion HP-20 in fermentations eliminated toxic effects on growth and reduced feedback repression of teicoplanin by adsorption. There was a 4.2-fold increase in the quantities of teicoplanin. Addition of adsorbent assisted in the recovery of teicoplanin by reducing the recovery steps. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study provide useful information for the production of teicoplanin, a glycopeptide antibiotic produced by Actinoplanes teicomyceticus. Addition of adsorbent in fermentation increased productivity of teicoplanin by more than five times.

Actinomycetales↗

PubMed2001

Biflavonoids from Ouratea multiflora.

A new flavone dimer, 3-hydroxy-4',5,7-trimethoxyflavone-(6-->8")-3"-hydroxy-3"',4"', 5",7"-tetramethoxyflavone, together with amenthoflavone, have been isolated from the leaves of Ouratea multiflora. Its structure was established by spectroscopic methods, including two-dimensional NMR spectroscopy.

Flavonoids↗

PubMed2001

Overexpression of p53 and absent genetic mutation in clear cell chondrosarcoma.

Clear cell chondrosarcoma is one of the extremely rare chondrosarcomas. The pathogenesis and the molecular genetic events, which contribute to the development of clear cell chondrosarcoma, are not well elucidated, due in part to the lack of sufficient tumor tissue available. To characterize the involvement of the p53 gene abnormality in this disease, we analyzed expression and sequence alteration of p53 by immunohistochemical analysis of the protein expression and quantitative DNA/PCR and PCR-SSCP assays of the gene in 28 paraffin-embedded tissue specimens. Immunohistochemical analysis demonstrated that 7 (25%) showed patchy positive nuclear staining for p53 and 5 (18%) showed diffuse positive nuclear staining patterns. Sixteen (57%) were negative for p53 immunostaining. Quantitative DNA/PCR analysis revealed that none of the cases we studied showed significantly reduced levels of p53 amplification (<0.50), strongly suggesting an allelic deletion of the p53 gene. In contrast, however, DNA/PCR-SSCP analysis failed to detect any types of mutations resulting in amino acid substitution within exons 5-9 regions of the gene. Taken together, our data suggest that genetic alteration of p53 is a relatively rare event in clear cell chondrosarcomas but a substantial fraction of this type of tumors carries abnormal overexpression of p53, which might result from an as yet unidentified mechanism(s).

Chondrosarcoma↗

PubMed2000

Spectroscopic properties of fluoroquinolone antibiotics and nanosecond solvation dynamics in aerosol-OT reverse micelles.

Among fluoroquinolone antibiotics, ofloxacin (OFL) and norfloxacin (NOR) have piperazinyl groups but flumequine (FLU) does not have this substitutent. The emission spectra of OFL and NOR are strong, broad structureless bands with large Stokes' shifts in water but the emission intensities are very weak in organic solvents. Thus we find that these compounds exist as different chemical species in various solvents. A continuous red shift in the emission bands for OFL and NOR is observed as the water concentration within the aerosol-OT (AOT; sodium 1,4-bis[2-ethylhexyl]sulfosuccinate) micelle increases or temperature of this solution rises. From the fluorescence anisotropy measurements of OFL and NOR, we assume the intramolecular charge transfer after excitation from the nitrogen of the piperazinyl group to the keto oxygen. Theoretical calculations further support this observation. Multifrequency phase and modulation experiments and time-resolved emission spectra clearly show the occurrence of intramolecular charge transfer and the subsequent nanosecond water reorganization around OFL or NOR in the AOT micelle. Upon increasing the water concentration within the AOT micelle, the relaxation rate increases because of the large amount of free water. The emission spectra of FLU do not exhibit any significant response to the physical properties of their environment.

Anti-Infective Agents↗

PubMed2000

Prediction on lengths of stay in the postanesthesia care unit following general anesthesia: preliminary study of the neural network and logistic regression modelling.

The length of stay in the postanesthesia care unit (PACU) following general anesthesia in adults is an important issue. A model, which can predict the results of PACU stays, could improve the utilization of PACU and operating room resources through a more efficient arrangement. The purpose of study was to compare the performance of neural network to logistic regression analysis using clinical sets of data from adult patients undergoing general anesthesia. An artificial neural network was trained with 409 clinical sets using backward error propagation and validated through independent testing of 183 records. Twenty-two inputs were used to find determinants and to predict categorical values. Logistic regression analysis was performed to provide a comparison. The neural network correctly predicted in 81.4% of situations and identified discriminating variables (intubated state, sex, neuromuscular blocker and intraoperative use of opioid), whereas the figure was 65.0% in logistic regression analysis. We concluded that the neural network could provide a useful predictive model for the optimization of limited resources. The neural network is a new alternative classifying method for developing a predictive paradigm, and it has a higher classifying performance compared to the logistic regression model.

Adult↗

PubMed1998

Immortalization of osteoclast precursors by targeting Bcl -XL and Simian virus 40 large T antigen to the osteoclast lineage in transgenic mice.

Cellular and molecular characterization of osteoclasts (OCL) has been extremely difficult since OCL are rare cells, and are difficult to isolate in large numbers. We used the tartrate-resistant acid phosphatase promoter to target the bcl-XL and/or Simian Virus 40 large T antigen (Tag) genes to cells in the OCL lineage in transgenic mice as a means of immortalizing OCL precursors. Immunocytochemical studies confirmed that we had targeted Bcl-XL and/or Tag to OCL, and transformed and mitotic OCL were readily apparent in bones from both Tag and bcl-XL/Tag mice. OCL formation in primary bone marrow cultures from bcl-XL, Tag, or bcl-XL/Tag mice was twofold greater compared with that of nontransgenic littermates. Bone marrow cells from bcl-XL/Tag mice, but not from singly transgenic bcl-XL or Tag mice, have survived in continuous culture for more than a year. These cells form high numbers of bone-resorbing OCL when cultured using standard conditions for inducing OCL formation, with approximately 50% of the mononuclear cells incorporated into OCL. The OCL that form express calcitonin receptors and contract in response to calcitonin. Studies examining the proliferative capacity and the resistance of OCL precursors from these transgenic mice to apoptosis demonstrated that the increased numbers of OCL precursors in marrow from bcl-XL/Tag mice was due to their increased survival rather than an increased proliferative capacity compared with Tag, bcl-XL, or normal mice. Histomorphometric studies of bones from bcl-XL/Tag mice also confirmed that there were increased numbers of OCL precursors (TRAP + mononuclear cells) present in vivo. These data demonstrate that by targeting both bcl-XL and Tag to cells in the OCL lineage, we have immortalized OCL precursors that form bone-resorbing OCL with an efficiency that is 300-500 times greater than that of normal marrow.

Acid Phosphatase↗

PubMed1998

Licochalcone A: an inducer of cell differentiation and cytotoxic agent from Pogostemon cablin.

Licochalcone A (1), ombuin (2), and 5,7-dihydroxy-3',4'-dimethoxyflavanone (3) were isolated from the aerial parts of Pogostemon cablin by cytotoxicity-guided fractionation. Compound 1 showed in vitro cytotoxicity and Pl-PLC gamma 1 inhibition activity. Treatment of promyelocytic leukemia cells (HL-60) with compound 1 induced terminal differentiation with the generation of monocyte using nonspecific acid esterase assay.

3T3 Cells↗

PubMed1998

Detection of t(11;22)(q24;q12) translocation of Ewing's sarcoma in paraffin embedded tissue by nested reverse transcription-polymerase chain reaction.

Ewing's sarcoma is a poorly characterized malignant tumor with a relatively uniform histologic appearance, made up of densely packed small cells with round to oval nuclei, without distinct cell borders and without any structural differentiation. Often the diagnosis has to be made by exclusion. Recently, it has been made possible to identify characteristic chromosomal rearrangements associated with certain solid tumors. More than 85% of Ewing's sarcoma and peripheral neuroectodermal tumor present a specific t(11;22)(q24;q12) balanced translocation, resulting in the production of a novel chimerical EWS/FLI-1 message. Using oligonucleotide primers derived from EWS and FLI-1 complementary DNAs, we were able to use reverse transcription-polymerase chain reaction (RT-PCR) as a diagnostic tool. The described nested RT-PCR method as another supportive diagnostic method enables pathologists to differentiate small blue cell tumors not only to make correct diagnosis but also to investigate retrospective archival tumor samples, using formalin fixed paraffin embedded tissue as a source of RNA.

Chromosomes, Human, Pair 11↗

PubMed1997

Assessment of the performance of a capture immunoassay for the bone isoform of alkaline phosphatase in serum.

We report the analytical validation of an immunocapture assay for the bone isoform of alkaline phosphatase in serum. A between batch imprecision of less than 10% was found, being about 8% at the upper limit of the reference range, and with a detection limit of 0.8 IU/l at 37 degrees C. The crossreactivity of the method with the liver isoform was found to be in the range of 3-13% depending on the method employed. Unexpectedly the correlation of results with a non-immunological method for the quantitation of bone ALP showed significant differences between samples from children and patients with Paget's disease, with an apparent lower level of capture in the case of children. These data suggest that there may be differences in the epitope recognised by the antibody, which may be due to the presence of different forms of bone enzyme in these two populations. The significance of these observations is not clear at this stage.

Alkaline Phosphatase↗

PubMed1997

In vitro neutralization of hepatitis B virus by monoclonal antibodies against the viral surface antigen.

In vitro HBV infection and neutralization were assayed using an anti-preS1 murine monoclonal antibody (1B3) and anti-preS2 (H69K) and anti-S (CS131A) murine-human chimeric antibodies. The 1B3 (IgG1) and H69K (IgG1) was constructed previously and the CS131A was constructed for this study by expressing stably the chimeric heavy and light chains in Chinese hamster ovary cells and purifying from the culture supernatant. Previous study showed that the H69K and CS131A recognize known virus-neutralizing epitopes, while the 1B3 does not. For the assays, adult human hepatocyte primary culture was infected with the adr or ayw subtype of HBV, and the infectivity and subsequent replication was confirmed both by measuring the kinetics of HB-sAg secretion by the infected cells and detecting the intermediate replicative form of HBV DNA in the cells. Next, the hepatocytes were infected with the adr or ayw subtype of the virus that had been preincubated with various concentrations of each of the antibodies and the neutralization of HBV was analyzed. The results showed that the anti-preS2 and anti-S chimeric antibodies exhibited neutralizing activity against both the adr and ayw subtypes of the virus, with approximately 1,000 and 2,000 times higher specific activity than polyclonal hepatitis B immune globulin, respectively, but the anti-preS1 antibody scarcely neutralized the infection. The neutralizing activities of the antibodies were consistent with their epitope specificity and antigenbinding affinity, suggesting that this neutralization assay is specific. The in vitro neutralization assay will be useful for evaluating the neutralizing activity of anti-HBV antibodies before in vivo testing in chimpanzees.

Adult↗

PubMed1996

The impact of osteonectin for differential diagnosis of osteogenic bone tumors: an immunohistochemical and in situ hybridization approach.

Thirty-three osteosarcomas at various grades of histologic differentiation, including chondroblastic, osteoblastic, and fibroblastic variants, were investigated immunohistochemically for evidence of osteonectin. Twenty-two cases of varying types of osteosarcoma were examined with in situ hybridization for mRNA expression of osteonectin. Immunohistochemically, osteonectin was present in all the osteosarcomas in this study. With in situ hybridization, 12 out of 22 osteosarcomas showed a positive signal. Two osteochondrosarcomas, seven chondrosarcomas, and one mesenchymal chondrosarcoma were also studied with regard to the localization of osteonectin, either immunohistochemically or by in situ hybridization. Immunohistochemically, osteonectin was present in all the chondroid lesions except for one osteochondroma. However, in situ hybridization of osteonectin mRNA was negative in all the chondroid lesions we studied. This study revealed that immunohistochemical localization of osteonectin is not useful in providing conclusive diagnosis of osteosarcoma. In situ hybridization of osteonectin mRNA might be useful in differentiating osteosarcoma from nonsteogenic bone tumors.

Antisense Elements (Genetics)↗

PubMed1996

Nucleotide-induced mucin release from primary hamster tracheal surface epithelial cells involves the P2u purinoceptor.

Mucin release by airway surface epithelial cells is regulated by extracellular adenosine triphosphate (ATP) via a P2 purinoceptor-mediated mechanism. The objective of the present experiment was to examine the possible involvement of uridine triphosphate (UTP) in this purinergic signal transduction pathway. Using primary hamster tracheal surface epithelial cells, ATP and UTP were compared in their abilities: 1) to displace ATP gamma S35-binding to intact cells; 2) to accumulate inositol phosphates; and 3) to stimulate mucin release. Finally, the presence of a P2u receptor message was examined. Our results showed that: 1) UTP was much less effective than ATP in displacing ATP gamma S35-binding (median inhibitory concentrations (IC50S) 240 vs 2.9 microM); 2) UTP was more potent than ATP in accumulating inositol phosphates (100 vs 43% increase at 2mM); 3) UTP was equipotent with ATP in stimulating mucin release; 4) Northern blot analysis of messenger ribonucleic acids (mRNAs) with a mouse P2u receptor complementary deoxyribonucleic acid (cDNA) probe revealed a single specific band (2.8 kb), partial sequencing of which showed a great homology with those of human or mouse P2u receptors. We conclude that, although both ATP and UTP are equipotent in stimulating mucin release, their binding kinetics to the cell surface are quite different, suggesting the presence of a common binding domain which may be responsible for the mucin release by these nucleotides. We suggest that the P2u purinoceptor is likely to be responsible for mucin release by these nucleotides, probably via activation of phospholipase C.

Adenosine Triphosphate↗

PubMed1996

Inclusion body myositis--a case report.

Inclusion body myositis is a rare myopathy that clinically resembles a chronic polymyositis and histopathologically is characterized by the presence of rimmed vacuoles containing ultrastructural cytoplasmic degradation products with filamentous intranuclear and cytoplasmic inclusions. Since clinical features are not uniform, histopathologic and ultrastructural studies are necessary to confirm the diagnosis. We report a typical case of inclusion body myositis with histopathologic and ultrastructural study. The patient was a 31 year old male who presented with progressive weakness of both forearms, hands and lower extremities for 10 years.

Adult↗