Search PubMed⌕ Search

Biomedical subjects

C Park

Publications and source records attributed to C Park.

At least 55 records · Page 3Linked to original sources
PubMed2001

Korean American health insurance and health services utilization.

The purpose of this ethnic group study was to describe the unique pattern of Korean Americans, as compared with the aggregate of Asian Americans, for: (a) the predisposing, enabling, and need factors for health service utilization, focusing specifically on the role of health insurance coverage; and (b) predictors of health insurance coverage. Using the behavioral model for health service utilization, data were selected from the 1992 National Health Insurance Survey (NHIS, 1994) for Korean Americans (n = 345) and Asian Americans (n = 3,059). Results differed between the Korean American group and the Asian American group. Health insurance coverage was the strongest predictor of Korean American utilization, and need factors lacked significance, suggesting that uninsured Korean Americans have less access regardless of need. For the aggregate Asian American group, need factors tempered the influence of health insurance on utilization. Results of this type of study may be helpful for designing and implementing health care services tailored for specific ethnic at-risk markets.

Adolescent↗
PubMed2001

The laryngeal mask airway in infants and children.

PURPOSE: To compare the effectiveness of various laryngeal mask airway (LMA) sizes and their performance during positive pressure ventilation (PPV) in paralyzed pediatric patients. METHODS: Pediatric patients (n = 158), < 30 kg, ASA 1 or 2 were studied. After paralysis, an LMA of the recommended size was inserted and connected to a volume ventilator. Fibreoptic bronchoscopy (FOB) was performed and graded: 1, larynx only seen; 2, larynx and epiglottis posterior surface seen; 3, larynx, and epiglottis tip or anterior surface seen--visual obstruction of epiglottis to larynx: < 50%; 4, epiglottis down-folded, and its anterior surface seen--visual obstruction of epiglottis to larynx: > 50%; 5, epiglottis down-folded and larynx not seen directly. Inspiratory and expiratory tidal volumes (V(T)), and airway pressure were measured by a pneumo-tachometer, and the fraction of leakage (F(L)) was calculated. In 79 cases, LMA was used for airway maintenance throughout surgery. RESULTS: Successful LMA placement was achieved in 98% of cases: three failures were due to gastric insufflation. For LMA # 1, 1.5, 2, and 2.5, FOB grades [median (range)] were 3(1-5), 3(1-5), 1(1-5) and 1(1-3) respectively. In smaller LMAs, the cuff more frequently enclosed the epiglottis (P < .001). F(L) of LMA # 1 was higher than those of LMA # 1.5 and LMA # 2.5 (P < .05), and F(L) of LMA # 2 was higher than that of LMA # 2.5 (P < .05). In the 79 patients, the number of patients experiencing complications decreased as LMA size increased (P < .05). CONCLUSION: Use of the LMA in smaller children results in more airway obstruction, higher ventilatory pressures, larger inspiratory leak, and more complications than in older children.

Child↗
PubMed2001

Chromosomal alterations in paired gastric adenomas and carcinomas.

Gastric adenoma is a precancerous lesion of the stomach and its malignant transformation is thought to result from accumulative series of gene alterations. The aim of this study was to determine the pattern of chromosomal changes during gastric carcinogenesis. Pairs of adenoma and carcinoma tissues from 15 gastrectomy cases containing both adenomas and carcinomas in the same (adjacent pairs, 6 cases) and different (non-adjacent pairs, 9 cases) lesions, were analyzed for chromosomal alterations of 39 non-acrocentric chromosomal arms by comparative genomic hybridization (CGH). CGH analysis identified frequent chromosomal alterations in most of the gastric adenomas (14/15, 93%) and all of the carcinomas. The mean number of chromosomal alterations was higher in carcinoma (5.5 for adenoma and 11.7 for carcinoma; P = 0.006, by nonparametric Wilcoxon's test). Losses on the short arm of chromosome 17 were most common in both adenomas (43%) and carcinomas (67%). The pattern of chromosomal alterations in paired gastric adenomas and carcinomas showed greater similarity compared to the non-case pairs and this similarity was increased in the adjacent pairs. Deletion mapping analysis on chromosome 17p also demonstrated that the conserved deletion area was more frequent in the adjacent pairs. Among these 6 adjacent pairs, all had common deletion areas. In contrast, among the 9 non-adjacent pairs, 2 (22%) had common area of deletion, 5 (56%) showed deletion only in the carcinoma, and the remaining 2 (22%) had no deletion on 17p, suggesting diverse genetic changes might be involved in the multiple tumor formation. Our results that common clonal genetic changes between adjacent pairs of gastric adenomas and carcinomas and accumulated genetic changes in the carcinomas provide evidences for the stepwise mode of gastric carcinogenesis through the accumulation of a series of genetic alterations.

Adenoma↗
PubMed2001

HER-2 and choice of adjuvant chemotherapy in breast cancer.

The amplification or overexpression of HER-2 is a recognized prognostic marker that is associated with poor survival for patients with node-positive breast cancer. Several studies have demonstrated that HER-2 may serve to direct the selection of optimal adjuvant chemotherapy. This article provides a critical review of the studies that offer evidence for the role of HER-2 as a predictor of response to chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

The H1 double-stranded RNA genome of Ustilago maydis virus-H1 encodes a polyprotein that contains structural motifs for capsid polypeptide, papain-like protease, and RNA-dependent RNA polymerase.

The Ustilago maydis viral (UmV) genome consists of three distinct size groups of double-stranded RNA (dsRNA) segments: H (heavy), M (medium), and L (light). The H segments have been suggested to encode all essential viral proteins, but without any molecular evidences. As a preliminary step to understand viral genomic organization and the molecular mechanism governing gene expression in UmV, we determined the complete nucleotide sequence of the H1 dsRNA genome in P1 viral killer subtype. The H1 dsRNA genome (designated UmV-H1) contained a single open reading frame that encodes a polyprotein of 1820 residues, which is predicted to be autocatalytically processed by a viral papain-like protease to generate viral proteins. The amino-terminal region is the capsid polypeptide with a predicted molecular mass of 79.9 kDa. The carboxy-terminal region is the RNA-dependent RNA polymerase (RDRP) that has a high sequence homology to those of the totiviruses. The H2 dsRNA also encodes a distinct RDRP, suggesting that UmV is a complex virus system like the Saccharomyces cerevisiae viruses ScV-L1 and -La.

Amino Acid Sequence↗
PubMed2001

In vitro and in vivo characterization of 67Ga(3+) complexes with cis,cis-1,3,5-triamino-cyclohexane-N,N',N"-triacetic acid derivatives.

The aim of this study was to investigate the in vitro and in vivo performance of a 67Ga complex with cis,cis-1,3,5-triaminocyclohexane-N,N',N"-triacetic acid (tachta) as a potential ligand for use as a Ga(III) radiopharmaceutical for PET imaging. The radiolabeling procedure, electrophoretic properties, lipophilicity, acid stability, human serum stability and biodistribution in mice of 67Ga(tachta) were investigated. The 67Ga(tachta) complex forms at 10(-3) M tachta concentration at 40 degrees C in 100% yield; it is neutral, non-lipophilic, 90% stable at pH = 4 and 5 and 100% stable at pH = 6, for at least 8 d. Serum stability experiments demonstrated that at 5 hr 67Ga(tachta) exists in serum as a free complex. At 24 hr, 30% of 67Ga(tachta) is reversibly bound to transferrin-albumin fraction of serum, and that this percentage remains unchanged for a period of 4 d. Biodistribution in mice showed that 67Ga(tachta) rapidly clears via the kidneys from the body with less than 10% of injected activity left in the body at 3 hours and only 6% remaining after 24 hr. The complex also cleared rapidly from all of the major organs, with bone showing some slightly increased (1.15% ID/g) 24 hr accumulation, in comparison with the 3 hr time point. Based upon these data, 67Ga(tachta) may be considered as a candidate for developing new Ga(III) radiopharmaceuticals for PET.

Animals↗
PubMed2001

Expression of corticotropin releasing hormone receptors type I and type II mRNA in suicide victims and controls.

Corticotropin-releasing hormone (CRH) is a key neuroendocrine factor implementing endocrine, immune and behavioral responses to stress. CRH exerts its action through two major receptors, CRH-R1 and CRH-R2. Recently novel non-peptidic antagonists directed against CRH-R1 or CRH-R2 have been proposed as promising agents in the treatment of depression, anxiety and eating disorder. However, so far the CRH-receptor system has not been widely studied in humans. Therefore, we employed quantitative TaqMan PCR to analyze the expression and distribution of both CRH-R1 and CRH-R2 in human brain tissue and peripheral organs. Furthermore the expression of CRH receptors was analyzed for the first time in pituitaries of suicide victims by in situ hybridization and quantitative PCR. Our data demonstrated a different expression pattern in humans as compared to rodents. Both CRH-R1 and CRH-R2 were expressed in high amounts in the brain with the strongest expression in the pituitary. As described in rodents, however the CRH-R1 in human was the predominant receptor in the brain (82.7 +/- 11.0%), whilst CRH-R2 was the predominant receptor in peripheral organs (77.0 +/- 15.8%). There was a shift in the ratio of CRH-R1/R2 in the pituitaries of suicide victims. In conclusion, both CRH-R1 and CRH-R2 are widely expressed in human tissues with a distribution substantially different from rodents. Strong expression of both CRH-R1 and CRH-R2 in human pituitaries suggests that particularly under stress, activation of the HPA axis can be maintained through both receptors.

Adolescent↗
PubMed2001

Development and mapping of microsatellites from a microdissected BTA 11-specific DNA library.

A chromosome-specific library was developed for Bos taurus autosome 11 by chromosome microdissection and microcloning using a bovine primary fibroblast culture, obtained from a t(X;23) heifer, that spontaneously developed a translocation chromosome involving bovine chromosome 11. The library was screened using (AC)12 oligos, positive clones selected, sequenced and primers developed to generate bovine chromosome 11-specific microsatellite markers. This study suggests that chromosome-specific libraries have great potential for development of microsatellite markers for the construction of marker-saturated linkage maps for each chromosome.

Animals↗
PubMed2001

Killer T-cell induction in patients with blastic natural killer cell lymphoma/leukaemia: implications for successful treatment and possible therapeutic strategies.

A rare form of putative natural killer (NK) cell lymphoma called blastic NK cell lymphoma appears to be clinicopathologically distinctive in showing a homogenous lymphoblast, variable expression of CD2, CD4, CD56 and TdT, negative for surface CD3, T-cell receptor antigen, CD16, CD34 and lack of association with Epstein-Barr virus (EBV). We report two patients with blastic NK cell lymphoma and describe the interesting clinical studies. The patients presented with cutaneous plaques. Both patients had adenopathy, and one had marrow involvement at presentation. Unlike in many NK and NK-like T-cell disorders, azurophilic cytoplasmic granules were absent. They expressed intermediate density CD45. In addition, the cells were positive for HLA-DR, CD2, CD4, CD56 and TdT, and negative for EBV transcripts. In spite of the advanced clinical stage, complete remission was achieved by conventional chemotherapy. After interleukin 2 expansion of tumour-infiltrating bone marrow and lymph node cells from the patients, cytotoxic T-cell lines with rearranged T-cell receptor genes were established. They showed specific killing activity against autologous tumour cells in an MHC-restricted fashion, with possible implications for treatment. In addition, upon cessation of maintenance chemotherapy, one patient developed overt leukaemia with blasts expressing CD33 antigens, suggesting a continuous spectrum of blastic NK cell lymphoma to myeloid/NK cell precursor acute leukaemia.

Aged↗
PubMed2001

Increased proliferation activities of vascular endothelial cells and tumour cells in residual hepatocellular carcinoma following transcatheter arterial embolization.

AIMS: Transcatheter arterial embolization induces extensive ischaemic necrosis or hypoxia via the obstruction of the hepatic artery in hepatocellular carcinoma (HCC). Ischaemia is strongly correlated with an increased expression of angiogenic factor and stimulates an increase in angiogenesis, including endothelial cell proliferation. The aim of this study was to evaluate whether ischaemic necrosis induced by transcatheter arterial embolization could increase the proliferative activities of intratumoral endothelial cells or tumour cells in the residual HCC. METHODS AND RESULTS: Using a double immunohistochemical technique (Ki67 antibody to determine the proliferative activity and CD34 antibody to highlight the intratumoral endothelial cells), we performed immunohistochemical staining for 24 HCCs treated by transcatheter arterial embolization. Seven HCCs without any preoperative transcatheter arterial embolization and nine cirrhosis cases were also studied as the control cases. The residual tumour was then divided into five areas at 0.5 mm intervals, according to the distance from the necrotic margin induced by embolization. The Ki67 labelling indices of the intratumoral endothelial cells and tumour cells were counted in each area. The correlation between the indices and the corresponding distance from the ischaemic necrosis was analysed. The Ki67 labelling index of intratumoral vascular endothelial cells in the area less than 0.5 mm from the necrotic margin (area 1) was 10.60 +/- 3.64% (mean +/- SD), which was twofold greater than those of the other areas more than 0.5 mm from the margin (areas 2--5) and those of the control HCCs without preoperative transcatheter arterial embolization. In addition, the proliferation labelling index of the tumour cells was 35.77 +/- 11.45% (mean +/- SD) in area 1. This was higher than those of areas 2--5 and control HCCs without preoperative transcatheter arterial embolization. There was a positive correlation between the proliferation of both endothelial and tumour cells and ischaemic necrosis (P < 0.05). CONCLUSIONS: Our study suggests that the proliferative activity of intratumoral endothelial cells and tumour cells is increased by ischaemic necrosis induced by transcatheter arterial embolization, and its effect is maximal in the area adjacent to the necrosis (less than 0.5 mm from the necrotic margin).

Adult↗
PubMed2001

Expression of hepatitis B virus X protein is closely correlated with the high periportal inflammatory activity of liver diseases.

Hepatitis B virus X (HBx) protein is a multifunctional protein that exerts dual activity on cell proliferation and death. Although HBx is thought to be a major determinant that leads to hepatocellular carcinoma, its pathophysiological role in humans remains to be established. Attempts have been made to evaluate the role of HBx in liver specimens derived from patients with chronic B viral hepatitis and hepatocellular carcinoma. Among 25 paired liver specimens of hepatocellular carcinoma and corresponding nontumour liver tissues, HBx mRNA was hardly detected and was significantly lower than other HBV transcripts. An immunohistochemical study demonstrated that expression of HBx protein was also lower than other HBV gene products. Interestingly, however, expression of HBx protein changed with the progression of chronic hepatitis. HBx was expressed in 5.0% of patients with chronic hepatitis without cirrhosis but increased to 44.8% in chronic hepatitis with cirrhosis. In contrast, only one (3.7%) of 27 hepatocellular carcinomas showed HBx positivity whereas 29.6% of surrounding nontumour tissues was still HBx-positive. These results suggest that HBx may play a major role at the promotion stage of carcinogenesis. Noticeably, HBx-positive cells were preferentially localized in the periportal region of chronic hepatitis or periphery of cirrhotic nodules where high necroinflammatory activity was accompanied. We found a positive correlation between HBx expression and periportal inflammatory activity (P < 0.001). Thus, HBx may potentiate cell destruction and regeneration of liver that provide an opportunity for the accumulation of genetic mutations, which contribute to multistep hepatocarcinogenesis.

Carcinoma, Hepatocellular↗
PubMed2001

Protective effects of Debo on zinc-induced apoptosis of C6 glial cells via modulation of intracellular antioxidant, reduced glutathione.

In the present study, the mechanical basis of a traditional herbal prescription, Debo. on cytotoxic damage of the brain cells including C6 glial and PC12 cells has been studied. Traditionally, Debo has been employed for the purpose of preventing responses to trauma, ischemia, and other diseases in the nervous system. C6 glial cells were exposed to oxidative stress through the imployment of ZnCl2, and generates H2O2 and hydroxyl radicals by fenton reaction. ZnCl2-induced death of C6 glial cells, which was revealed as apoptosis by chromatin condensation as well as DNA fragmentation. Pretreatment of Debo significantly prevented apoptotic death of C6 glial cells via inhibition of H2O, generation as well as the recovering of an antioxidant, reduced glutathione (GSH). Also, deprivation of serum and glucose, found in ischemia, deceased the viability of PC12 cells up to 60% via generation of H2O2. However, Debo significantly protected cells from ischemic damage through decrease in H2O, generation. Furthermore, Debo markedly inhibited the transcriptional activation of NF-kappaB by ZnCI, in C6 glial cells. These results suggest that Debo may function as an antioxidant system against free radicals and be applicable to protect brain cells against oxidative or ischemic stresses.

Animals↗
PubMed2001

Lovastatin-induced E2F-1 modulation and its effect on prostate cancer cell death.

Lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, induces growth arrest in a variety of cancer cell lines. Its mechanism of action, however, has not been completely elucidated. E2F-1 is thought to act as an oncogene and a tumour suppressor, with its action probably dependent upon the cellular context. We have shown in this study that transcriptional regulation and proteasomal degradation of E2F-1 are critical regulatory events in lovastatin-induced cell death. Accompanying this is a reduction in the E2F-1-regulated expression of cell cycle genes such as c-myc, cyclin D1, cyclin A and cyclin B1. Cell cycle analysis demonstrated that the accumulation of apoptotic cells was preceded by a progressive decrease in the S-phase cell population in response to lovastatin. Although expression of E2F-1 was reduced in three prostate cancer cell lines-PC-3, LNCaP and DU-145-the p21 and p27 protein levels were not increased in all the cell lines treated, suggesting that increase in p21 and p27 protein expression per se is not responsible for lovastatin-mediated down-regulation of E2F-1. The subsequent apoptotic death of these cells in the presence of lovastatin can be prevented by forced ectopic expression of E2F-1. Taken together, these facts imply that E2F-1 is the target of an HMG-CoA inhibitor and critical cell death mediator in prostate cancer cells.

Apoptosis↗
PubMed2001

Adjacent cysteine residues as a redox switch.

Oxidation of adjacent cysteine residues into a cystine forms a strained eight-membered ring. This motif was tested as the basis for an enzyme with an artificial redox switch. Adjacent cysteine residues were introduced into two different structural contexts in ribonuclease A (RNase A) by site-directed mutagenesis to produce the A5C/A6C and S15C/S16C variants. Ala5 and Ala6 are located in an alpha-helix, whereas Ser15 and Ser16 are located in a surface loop. Only A5C/A6C RNase A had the desired property. The catalytic activity of this variant decreases by 70% upon oxidation. The new disulfide bond also decreases the conformational stability of the A5C/A6C variant. Reduction with dithiothreitol restores full enzymatic activity. Thus, the insertion of adjacent cysteine residues in a proper context can be used to modulate enzymatic activity.

Alanine↗
PubMed2001

Effect of breed and age of hens on the yolk to albumen ratio in two different genetic stocks.

A commercial egg-type chicken (ISA Brown; CEC) and a dual-purpose pure breed of the Korean Native Chicken (KNC) were compared for yolk to albumen (Y:A) ratio and their major egg characteristics at seven different ages. The eggs from KNC were significantly (P < 0.01) lighter in egg, albumen, and shell weight than those from CEC. However, the yolk weight and Y:A ratio of the eggs from KNC were significantly (P < 0.01) heavier or larger than the ones of CEC. The effect of age on the yolk, shell weight, and shell thickness was highly significant (P < 0.01), whereas significant differences were not found for Y:A ratio and other major egg components. The breed-by-age-of-hen interactions were significant for shell weight (P < 0.03) and shell thickness (P < 0.01). The yolk, albumen, and shell weight were positively (P < 0.001) associated with egg weight in both breeds. The association of Y:A ratio with egg weight in both breeds also were highly significant (P < 0.001) but negative. The results of the present study indicated that the different effects on the Y:A ratio were due to breed rather than age. Results suggest that the eggs from KNC are more desirable for use in products made of yolk than for consumption as table eggs.

Aging↗
PubMed2001

Total ear reconstruction in the devascularized temporoparietal region: I. Use of the contralateral temporoparietal fascial free flap.

Total ear reconstruction by the use of contralateral temporoparietal fascial free flap and autogenous costal cartilage was performed in 16 patients presenting with a devascularized temporoparietal region resulting from trauma or prior surgery. The microsurgical success rate was 87.5 percent (14 of 16 transplants). On evaluation of the final aesthetic result in 11 patients followed up for more than 3 years, nine patients were graded good-to-excellent and two patients exhibited fair-to-poor results. Despite the relatively long operating hours and the comparatively low microsurgical success rate, ear reconstruction by autogenous tissue transplantation has proved to be an encouraging and worthwhile experience. This article presents the clinical cases and discusses the technical details.

Adult↗