Biomedical subjects

Hong Kim

Publications and source records attributed to Hong Kim.

At least 37 records · Page 2Linked to original sources

PubMed2005

Modulation of E-cadherin by hepatocyte growth factor induces aggressiveness of gastric carcinoma.

OBJECTIVE: Hepatocyte growth factor (HGF) is well known as a scatter factor because it can disperse cells. E-cadherin is a protein that plays a main role in the establishment of cell-cell adhesion. This study focused on the role of HGF on the expression and distribution of E-cadherin. Furthermore, we found induction of aggressiveness of gastric carcinoma by modulation of E-cadherin by HGF. MATERIALS AND METHODS: Tumor tissues from 50 patients with gastric carcinoma were evaluated for the expression of HGF, its receptor c-Met, and E-cadherin. Western blot analysis and invasion assay were performed to confirm the role of HGF on the modulation of E-cadherin using human gastric cancer cell lines. RESULTS: Seventy-eight percent of the gastric carcinoma tissues showed overexpression of c-Met. E-cadherin expression was found in 86%, which could be further classified as membranous type (52%) or nonmembranous type (48%). The levels of HGF in tumor tissues increased significantly according to the tumor progression. The levels of HGF in tumors with nonmembranous type E-cadherin expression were significantly higher than those in tumors with membranous expression. A striking morphologic change from epithelial shape to fibroblastic shape was observed in SNU-16 cells after 3 days' exposure to HGF, accompanied by down-regulation of functional E-cadherin in the membrane. Treatment of the cells with HGF induced significant invasion into the matrigel. CONCLUSION: We can conclude that HGF can modulate the expression of E-cadherin in gastric carcinoma, which was accompanied by more aggressive phenotype.

Adult↗

PubMed2005

Differentiation of Mycobacterium species by analysis of the heat-shock protein 65 gene (hsp65).

The nucleotide sequences (604 bp) of partial heat-shock protein genes (hsp65) from 161 Mycobacterium strains containing 56 reference Mycobacterium species and 105 clinical isolates were determined and compared. hsp65 sequence analysis showed a higher degree of divergence between Mycobacterium species than did 16S rRNA gene analysis. Generally, the topology of the phylogenetic tree based on the hsp65 DNA sequences was similar to that of the 16S rRNA gene, thus revealing natural relationships among Mycobacterium species. When a direct sequencing protocol targeting 422 bp sequences was applied to 70 non-tuberculous mycobacterium (NTM) clinical isolates, all NTMs were clearly identified. In addition, an XhoI PCR restriction fragment length polymorphism analysis method for the differentiation of Mycobacterium tuberculosis complex from NTM strains was developed during this study. The results obtained suggest that 604 bp hsp65 sequences are useful for the phylogenetic analysis and species identification of mycobacteria.

Bacterial Proteins↗

PubMed2005

Molecular taxonomy of a soil actinomycete isolate, KCCM10454 showing neuroprotective activity by 16S rRNA and rpoB gene analysis.

Epilepsy constitutes a significant public health problem, and even the newest drugs and neurosurgical techniques have proven unable to cure the disease. In order to select a group of isolates which could generate an active compound with neuroprotective or antiepileptic properties, we isolated 517 actinomycete strains from soil samples taken from Jeju Island, in South Korea. We then screened these strains for possible anti-apoptotic effects against serum deprivation-induced hippocampal cell death, using the 3-(4, 5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT) assay as an in vitro test. The excitotoxic glutamate analog, kainic acid (KA), was used to induce seizures in experimental mice in our in vivo tests. As a result of this testing, we located one strain which exhibited profound neuroprotective activity. This strain was identified as a Streptomyces species, and exhibited the rifampin-resistant genotype, Asn(AAC)442, according to the results of 16S rRNA and rpoB gene analyses.

Animals↗

PubMed2004

Inhibitory effect of low-dose estrogen on neointimal formation after balloon injury of rat carotid artery.

The current regimens of hormone replacement therapy for postmenopausal women, estrogen combined with progestogen, have failed to show beneficial effects for the prevention of atherosclerotic disease. Although the relatively higher dose of estrogen contained in those regimens exerted adverse effects, there are few data examining a lower dose of estrogen in an atherosclerosis model. Therefore, we investigated experimentally whether lower doses of estrogen could inhibit neointimal formation after balloon injury of the rat carotid artery. Ten-week-old Wistar rats were subjected to ovariectomy or sham-operation (n=7). Four days after ovariectomy, rats were implanted with an osmotic mini-pump containing 17-beta estradiol (0.2, 1, 2, 10 and 20 microg/kg/day; n=6, 4, 8, 6 and 5, respectively) or placebo (n=10). After 3 days of hormone therapy, balloon injury was performed in the left common carotid artery. Neointimal formation was histologically evaluated 2 weeks after injury. Cross-sectional intimal area and the ratio of intimal area to medial area were dose-dependently reduced by estrogen replacement compared with those in ovariectomized rats without estrogen replacement. The effects of estrogen replacement were identical to those of an angiotensin II type 1 receptor blocker, candesartan. Interestingly, the effect was significant even in rats receiving lower doses of estrogen, in which plasma estradiol concentrations were not increased and the hyperplastic response of the uterus was minimal. These results suggest the efficacy of low-dose estrogen therapy for the protection of atherosclerosis.

Animals↗

PubMed2004

Age-dependence of the effect of treadmill exercise on cell proliferation in the dentate gyrus of rats.

The impact of age on the effect of treadmill exercise on cell proliferation in the dentate gyrus of rats was investigated via 5-bromo-2'-deoxyuridine immunohistochemistry. Animals of different ages were used: 4-week-old, 8-week-old, and 62-week-old. Based upon the present study, the most prominent cell proliferation in the dentate gyrus was observed in the 4-week-old rats, and decreased in direct relation to the age of the animals. In addition, although treadmill exercise increased cell proliferation in the dentate gyrus of animals in all age groups, the most potent enhancing effect appeared in the 8-week-old rats. The present results demonstrate that age is an important factor in the regulation of cell proliferation in the dentate gyrus and that the enhancing effect of the treadmill exercise on cell proliferation also depends on age status.

Aging↗

PubMed2004

Contributions of advective and diffusive oxygen transport through multilayer composite caps over mine waste.

The relative contributions of four mechanisms of oxygen transport in multilayer composite (MLC) caps placed over oxygen-consuming mine waste were evaluated using numerical and analytical methods. MLC caps are defined here as caps consisting of earthen and geosynthetic (polymeric) components where a composite barrier layer consisting of a geomembrane (1-2 mm thick polymeric sheet) overlying a clay layer is the primary barrier to transport. The transport mechanisms that were considered are gas-phase advective transport, gas-phase diffusive transport, liquid-phase advective transport via infiltrating precipitation and liquid-phase diffusive transport. A numerical model was developed to simulate gas-phase advective-diffusive transport of oxygen through a multilayer cap containing seven layers. This model was also used to simulate oxygen diffusion in the liquid phase. An approximate analytical method was used to compute the advective flux of oxygen in the liquid phase. The numerical model was verified for limiting cases using an analytical solution. Comparisons were also made between model predictions and field data for earthen caps reported by others. Results of the analysis show that the dominant mechanism for oxygen transport through MLC caps is gas-phase diffusion. For the cases that were considered, the gas-phase diffusive flux typically comprises at least 99% of the total oxygen flux. Thus, designers of MLC caps should focus on design elements and features that will limit diffusion of gas-phase oxygen.

Chemical Precipitation↗

PubMed2004

Administration of Ginseng radix decreases nitric oxide synthase expression in the hippocampus of streptozotocin-induced diabetic rats.

Nitric oxide (NO) is synthesized from L-arginine by nitric oxide synthase (NOS). Alternation of NOS expression is implicated in the pathogenesis of numerous secondary complications of diabetes. Aqueous extract of Ginseng radix has traditionally been used for the various disorders including diabetes. In this study, the effect of Ginseng radix on the NOS expression in the hippocampus of streptozotocin (STZ)-induced diabetic rats was investigated via nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry. Enhanced NOS expression was detected in the hippocampus of diabetic rats and administration of Ginseng radix suppressed NOS expression. Ginseng radix may aid the treatment of central nervous system complications in diabetes.

Animals↗

PubMed2003

Treadmill exercise suppresses food-deprivation-induced increase of nitric oxide synthase expression in rat paraventricular nucleus.

Exercise is known to potentially affect the eating patterns. In the present study, the effect of treadmill exercise on the expressions of nitric oxide synthase (NOS) and neuronal nitric oxide synthase (nNOS) in the paraventricular nucleus (PVN) of food-deprived rats was investigated using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and nNOS immunohistochemistry. The present results showed that food deprivation increased NOS and nNOS expressions in the PVN of the hypothalamus and treadmill exercise suppressed food deprivation-induced enhancing of NOS and nNOS expressions in the PVN. The most suppressive effect of treadmill exercise on the expressions of NOS and nNOS were observed in the heavy-intensity exercise group. Based on the present study, it is possible that treadmill exercise alleviates desire for food under food-deprivation conditions via modulation of NOS expression.

Animals↗

PubMed2003

Treadmill exercise decreases intrastriatal hemorrhage-induced neuronal cell death via suppression on caspase-3 expression in rats.

Intracerebral hemorrhage is one of the most devastating types of stroke. This disease is known to cause severe neurological damage and also has a very high mortality rate. In this study, the effect of treadmill exercise on intrastriatal hemorrhage-induced neuronal cell death was investigated. Intrastriatal hemorrhage was caused by injection of collagenase into the striatum using a stereotaxic instrument. Animals of the exercise group were made to run on a treadmill for 30 min once a day during 10 consecutive days. In the present results, treadmill exercise was shown to suppress the increase in the size of hemorrhage-induced lesions and the increase in caspase-3 expression in the striatum. Based on these results, it is possible that treadmill exercise aids in the recovery from central nervous system sequelae following intracerebral hemorrhage.

Animals↗

PubMed2003

Naloxone potentiates treadmill running-induced increase in c-Fos expression in rat hippocampus.

The expression of c-Fos is induced by a variety of stimuli and is sometimes used as a marker for increased neuronal activity. In the present study, the effect of treadmill running on c-Fos expression in the hippocampus and the involvement of opioid receptors were investigated via c-Fos immunohistochemistry. It was shown that c-Fos expression in the CA1 region, the CA2 and CA3 regions, and the dentate gyrus of the hippocampus was significantly increased by treadmill running and naloxone, a nonselective opioid receptors antagonist, treatment enhanced treadmill exercise-induced increase of hippocampal c-Fos expression. Base on the present results, it can be suggested that treadmill running increases hippocampal neuronal activity and that endogenous opioids curtail the exercise-induced increase.

Animals↗

PubMed2003

Treadmill exercise suppresses ischemia-induced increment in apoptosis and cell proliferation in hippocampal dentate gyrus of gerbils.

Cerebral ischemia resulting from transient or permanent occlusion of cerebral arteries leads to neuronal cell death and eventually causes neurological impairments. In the present study, the effects of treadmill exercise on apoptosis and cell proliferation in the hippocampal dentate gyrus following transient global ischemia in gerbils were investigated using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and immunohistochemistry for caspase-3 and 5-bromo-2'-deoxyuridine (BrdU). It was shown that apoptotic cell death and cell proliferation in the hippocampal dentate gyrus were significantly increased following transient global ischemia in gerbils and that treadmill exercise suppressed the ischemia-induced increase in apoptosis and cell proliferation in the dentate gyrus. The present results suggest that treadmill exercise may protect cells from apoptotic death and aid in recovery from the central nervous system sequelae following stroke.

Animals↗

PubMed2003

Acupuncture suppresses ischemia-induced increase in c-Fos expression and apoptosis in the hippocampal CA1 region in gerbils.

Acupuncture has been used for the enhancement of functional recovery from various disorders including stroke. In the present study, the effects of acupuncture on the c-Fos expression and apoptosis in the hippocampal CA1 region of gerbils following transient global ischemia were investigated via immunohistochemistry for c-Fos and caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Enhanced Fos, TUNEL, and caspase-3 positivities were detected in the hippocampal CA1 region in the ischemic gerbils. Acupunctural treatment suppressed the ischemia-induced increment in the number of Fos-, TUNEL-, and caspase-3-positive cells: the most potent suppressive effect was observed at the Zusanli acupoint. These results suggest that acupunctural treatment alleviates ischemia-induced apoptosis and may aid in the recovery following ischemic cerebral injury.

Acupuncture Therapy↗

PubMed2003

Treadmill exercise suppresses diabetes-induced increment of neuropeptide Y expression in the hypothalamus of rats.

Diabetes mellitus is a metabolic disorder with serious sequelae in humans. Hyperphagia is a characteristic symptom of diabetes and is a central nervous system-mediated disorder. Neuropeptide Y (NPY) is a 36-amino-acid peptide and is concentrated in the hypothalamus which is an appetite-regulating area. NPY is known to stimulate appetite and decrease energy expenditure. In the present study, the effect of treadmill exercise on the hypothalamic NPY expression in rats with streptozotocin (STZ)-induced diabetes was investigated via immunohistochemistry. Enhanced NPY expression in the paraventricular nucleus and arcuate nucleus was observed in the STZ-induced diabetic rats. Treadmill exercise suppressed a diabetes-induced increase of NPY expression. The present results suggest the possibility that treadmill exercise inhibits diabetes-induced increment of the desire for food.

Animals↗

PubMed2003

Use of high-performance liquid chromatographic and microbiological analyses for evaluating the presence or absence of active metabolites of the antifungal posaconazole in human plasma.

Posaconazole (SCH 56592) is a novel broad spectrum triazole antifungal agent that is currently in phase III clinical trials for the treatment of systemic fungal infections. This study was initiated to determine if orally administered posaconazole to humans would result in the formation of active metabolite(s). Plasma samples from a multiple-rising dose study in healthy volunteers were analyzed by validated HPLC and microbiological methods. The HPLC analysis involved extraction with a mixture of organic solvent (methylene chloride-hexane) followed by separation on a C18 column and quantification by UV absorbance at 262 nm. The microbiological assay was performed utilizing an agar diffusion method using Candida pseudorropicalis ATCC 46764 as the test organism. Potency was determined by comparing the growth inhibition zones produced by the test sample to those produced by standard concentrations prepared in plasma. Individual and mean plasma concentration-time profiles were similar for both HPLC and microbiological assays. The area under the plasma concentration-time curves of the microbiological and HPLC results were similar with a mean (RSD) ratio of 105.5% 15.3%), indicating that there was no relevant biologically active metabolite of posaconazole in human plasma.

Antifungal Agents↗

PubMed2003

Dependence of rat hippocampal c-Fos expression on intensity and duration of exercise.

The expression of c-Fos, an immediately early gene, is a marker of neural activity. In the present study, the effect of treadmill exercise on c-Fos expression was investigated in various regions of the rat hippocampus via immunohistochemistry. The first part of the experiment was aimed at determining the dependence of c-Fos expression on the intensity of treadmill exercise. In most of the hippocampal regions studied, increasing c-Fos expression was observed with increasing exercise intensity. In the second part of the experiment, the dependence of c-Fos expression on the duration of treadmill exercise was investigated. The c-Fos expression induced by mild-intensity exercise increased until the 7th day of exercise and subsequently decreased. Results of the present study suggest that the effect of treadmill exercise on neuronal activity in the hippocampus is intensity-and duration-dependent.

Animals↗

PubMed2003

Pharmacological characterization of isolated human prostate.

PURPOSE: Human prostate contains alpha-1 adrenergic, cholinergic and nonadrenergic noncholinergic neuroreceptors. Using agonistic and antagonistic agents at these neuroreceptors we studied the resultant contractile responses in isolated human prostate. MATERIALS AND METHODS: Human prostate tissue was obtained at prostatectomy for benign prostatic hyperplasia in 37 adult male patients. Tissues were suspended in tissue bath chambers connected to force displacement transducers. Specimens were subjected to agonist induced contractions, the first always being norepinephrine (NE). Specimens were pretreated with antagonist (adrenergic, cholinergic, nonadrenergic noncholinergic or none if control), followed by contraction with a second agonist (NE or other). Contractile tensions were recorded on a polygraph and then statistically analyzed. RESULTS: The order of highest to lowest agonist induced tensile forces was NE, dopamine, acetylcholine, bethanechol, histamine and serotonin. Excitatory concentration EC(50) values were determined for each agonist tested. Significant differences were found between specific alpha-1 adrenergic receptor blockers (terazosin, prazosin and the experimental drug LY253352). In addition, many other agents antagonized the alpha-1 adrenergic receptor. Inhibitory concentration IC(50) values were obtained and the order of alpha-1 adrenergic antagonistic strengths from strongest to weakest was LY253352, prazosin, terazosin, ketanserin, SCH23390, diphenhydramine, DO710, dopamine, serotonin and histamine. CONCLUSIONS: Human prostate neuroreceptors were determined to be alpha-1 adrenergic, dopaminergic, muscarinic cholinergic, 2A serotonergic and H1 histaminergic. Dopamine, serotonin, histamine and their antagonists blocked the adrenergic response, indicating possible receptor-receptor interaction. Further study of the pharmacology of human prostate would likely identify new drugs for treating patients with bladder outlet obstruction due to benign prostatic hyperplasia.

Adrenergic alpha-1 Receptor Antagonists↗

PubMed2003

Alterations of renal hemodynamics in unilateral ureteral obstruction mediated by activation of endothelin receptor subtypes.

PURPOSE: Unilateral ureteral obstruction (UUO) for 21 hours causes severe renal vasoconstriction. We examined the role of endothelin (ET)-A receptor in renal hemodynamic alterations induced by UUO. MATERIALS AND METHODS: Hemodynamic and clearance experiments were performed in 3 groups of anesthetized dogs. In group 1, 6 sham operated dogs received intrarenal infusion of the specific ET-A receptor antagonist BQ-610 (Peninsula Laboratories, Inc., Belmont, California), followed by infusion of the nitric oxide synthase substrate L-arginine. In the 7 group 2 dogs release of 21-hour UUO was followed by intrarenal infusion of BQ-610 and L-arginine. In the 5 group 3 dogs release of 21-hour UUO was followed by L-arginine infusion. RESULTS: UUO caused marked decreases in renal blood flow (RBF) and glomerular filtration rate (GFR) in groups 2 and 3 compared with group 1. In group 1 BQ-610 and L-arginine infusion did not alter RBF or GFR. In contrast, BQ-610 infusion in group 2 after UUO release led to a significant increase in RBF and GFR as well as additional increases after L-arginine infusion. After UUO release in group 3 L-arginine infusion alone did not change RBF or GFR. CONCLUSIONS: After UUO release blockade of the ET-A receptor ameliorates renal vasoconstriction. The addition of L-arginine, which is a substrate for nitric oxide synthase, superimposed on ET-A receptor blockade confers a further decrease in renal vascular resistance, suggesting that the ET and L-arginine-nitric oxide systems are involved in renal hemodynamic alterations caused by UUO.

Animals↗

PubMed2003

Acupuncture increases nitric oxide synthase expression in hippocampus of streptozotocin-induced diabetic rats.

In the present study, the effect of acupuncture at Zusanli acupoint on nitric oxide synthase (NOS) expression in the hippocampus of streptozotocin (STZ)-induced diabetic rats was investigated via nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry. Animals were divided into four groups: the control group, the nondiabetic and acupunctured group, the STZ-induced diabetes group, and the STZ-induced diabetes and acupunctured group. From the results, NADPH-d-positive neurons in the hippocampus were decreased in STZ-induced diabetic rats, while acupuncture increased NOS expression significantly under diabetic conditions. In the present study, it can be suggested that acupuncture treatment may modulate NOS activity in the hippocampus under diabetic conditions.

Acupuncture↗