Search PubMed⌕ Search

Biomedical subjects

Y S Chang

Publications and source records attributed to Y S Chang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Ovarian hyperstimulation syndrome complicating a spontaneous singleton pregnancy: a case report.

It has been known that most cases of ovarian hyperstimulation syndrome (OHSS) are associated with the use of exogenous gonadotropins to induce multiple ovulation. However, OHSS is infrequently associated with a spontaneous ovulatory cycle, usually in the case of multiple gestations, hypothyroidism, or polycystic ovarian syndrome. We report a case of severe OHSS in a spontaneously pregnant woman with no underlying disease.

Adult↗
PubMed2001

The enhanced effect of a hexameric deoxyriboguanosine run conjugation to CpG oligodeoxynucleotides on protection against allergic asthma.

BACKGROUND: Oligodeoxynucleotides containing a CpG motif (CpG ODNs), as potent inducers of T(H)1 immunity, are considered promising candidates for immune modulation in asthma. We have previously demonstrated that conjugation of a hexameric deoxyriboguanosine run to the 3' terminus (3' dG(6)-run) of phosphodiester (PE) CpG ODNs enhanced their immuno-stimulatory activities in vitro. OBJECTIVE: This study aimed to evaluate the effect of a 3' dG(6)-run conjugation to PE or phosphorothioate (PS) CpG ODNs on protection against murine allergic asthma in vivo. METHODS: Balb/c mice were sensitized to ovalbumin by intraperitoneal injection with or without CpG ODNs (PS CpG ODNs, PE CpG ODNs, and those with 3' dG(6)-run) and subsequently challenged with ovalbumin. We evaluated airway hyperresponsiveness, eosinophil proportion in bronchoalveolar lavage fluid, airway inflammation, and ovalbumin-specific antibody responses. RESULTS: The conjugation of a 3' dG(6)-run to PE CpG ODNs enhanced the production of IFN-gamma from ovalbumin-specific T(H) cells and prevented the development of asthma in terms of airway hyperresponsiveness, airway eosinophilia, and ovalbumin-specific IgE responses; these effects were comparable to those of PS CpG ODNs. Enhanced effects of the 3' dG(6)-run were also observed in PS CpG ODNs, though they were lower than those in PE CpG ODNs. CONCLUSION: This study suggests that conjugation of a 3' dG(6)-run to CpG ODNs might provide an effective method for immune modulation of allergic asthma.

Animals↗
PubMed2001

Helicobacter pylori infection in rural China: exposure to domestic animals during childhood and adulthood.

Little is known about the mode of transmission of Helicobacter pylori, one of the most common human bacterial infections. Some domestic animals, including the cat, have been suggested as a reservoir of H. pylori disease, but the data have been inconsistent. This paper evaluates the role of exposure to pets and other domestic animals in the etiology of H. pylori in a rural area of China with a high prevalence of H. pylori infection. In this double-blind, population-based, cross-sectional investigation, interviews were completed with 3,288 (1994 seropositive, 1,019 seronegative, 275 indeterminate) H. pylori-infected adults enrolled in a randomized intervention trial in Linqu County, Shandong Province, China. We found no evidence to suggest that exposure to pets or other domestic animals during either childhood or adulthood was related to the prevalence of H. pylori infection. In fact, odds ratios (ORs) were reduced for subjects who had kept a cat (OR = 0.7, 95% CI = 0.4-1.0) or any animal (OR = 0.5, 95% CI = 0.3-0.9) in the house as an adult, or a cat as a child (OR = 0.7, 95% CI =0.5-1.0). ORs were also reduced for all 11 types of animal studied that subjects had kept in their courtyard as an adult. These findings suggest that zoonotic transmission, including that from domestic cats, is an unlikely route of H. pylori infection in this rural Chinese population.

Adult↗
PubMed2001

Meteorological effects on the evolution of high ozone episodes in the greater Seoul area.

Three high O3 episodes--7 days in 1992 (July 3-July 9), 9 days in 1994 (July 21-July 29), and another 3 days in 1994 (August 22-August 24)--were selected on the basis of morning (7:00 a.m.-10:00 a.m.) average wind direction and speed and daily maximum O3 concentrations in the greater Seoul, Korea, of 1990-1997. To better understand their characteristics and life cycles, surface data from the Seoul Weather Station (SWS) and surface and 850-hPa wind field data covering northeast Asia around the Korean Peninsula were used for the analysis. In the July 1992 episode, westerly winds were most frequent as a result of the influence of a high-pressure system west of the Korean Peninsula behind a trough. In contrast, in the July 1994 episode, easterly winds were most frequent as a result of the effect of a typhoon moving north from the south of Japan. Despite different prevailing wind directions, the peak O3 concentrations for each episode occurred when a sea/land breeze developed in association with weak synoptic forcing. The August 1994 episode, which was selected as being representative of calm conditions, was another typical example in which a well-developed

Environmental Monitoring↗
PubMed2001

Thyroxine treatment induces upregulation of renin-angiotensin-aldosterone system due to decreasing effective plasma volume in patients with primary myxoedema.

BACKGROUND: In experimental animals and humans, hypothyroidism is associated with fluid retention and generalized oedema, increased antidiuretic hormone (ADH), decreased atrial natriuretic hormone (ANH), and decreased renin-angiotensin-aldosterone system (RAAS), which subsequently can be corrected by thyroid hormone replacement. The purpose of this study was to determine the effect of thyroxine therapy on RAAS and neurohormones affecting water and electrolyte metabolism and the reason for these changes in patients with primary myxoedema. METHODS: We measured changes in the plasma renin activity (PRA), serum aldosterone (Aldo), ADH, ANH levels, serum and 24 h urinary electrolytes and osmolalities, and cardiac function in 22 female patients with primary myxoedema before and after correction of hypothyroidism. We also evaluated age-, sex-, and BMI-matched 15 healthy control subjects (Cont). RESULTS: It took an average of 4.3 months (range, 3-9 months) to normalize thyroid function. The mean reductions of body weight and estimated plasma volume were 1.8+/-1.0 kg (P=0.002) and 8.5% (P<0.001), respectively. In addition, serum Na+ and osmolality and the haematocrit were significantly elevated after correction of hypothyroidism (P<0.01 and P<0.001, respectively). Increased F(E)Na and C(OSM) (P<0.05) levels in patients with hypothyroidism (Ho) compared with those in Cont did not change after thyroxine therapy (Eu). However, C(H(2)O), U(E)K, F(E)K, and TTKG levels as well as creatinine clearance (Ccr) were markedly increased in Eu compared with Ho and Cont (P<0.01, respectively). Increased plasma ADH concentration and decreased plasma ANH concentration were normalized compared to Cont after thyroxine therapy (P<0.001 and P<0.01, respectively). Low PRA and serum Aldo concentration in Ho were significantly increased in Eu (P<0.001 and P<0.01, respectively). In addition, increased left ventricular mass index and decreased cardiac output in Ho were normalized compared to Cont after thyroxine therapy (P<0.01, respectively) CONCLUSIONS: These findings suggest that the exaggerated upregulation of RAAS after correction of hypothyroidism in patients with primary myxoedema is associated with an increase in Ccr and a decrease in plasma volume resulting from water diuresis, natriuresis, osmotic diuresis and inappropriate changes in plasma ADH and ANH levels. The improved renal function coincided with an amelioration of cardiac function. These changes seem to be an adaptive response for preventing excessive plasma volume and weight loss after thyroxine therapy.

Adult↗
PubMed2001

An intervention trial to inhibit the progression of precancerous gastric lesions: compliance, serum micronutrients and S-allyl cysteine levels, and toxicity.

Gastric cancer is the second most frequent cause of death from cancer in the world and the leading cause of death from cancer in China. In September 1995, we launched a randomized multi-intervention trial to inhibit the progression of precancerous gastric lesions in Linqu County, Shandong Province, an area of China with one of the world's highest rates of gastric cancer. Treatment compliance was measured by pill counts and quarterly serum concentrations of vitamin C, vitamin E and S-allyl cysteine. In 1999, toxicity information was collected from each trial participant to evaluate treatment-related side-effects during the trial. Compliance rates were 93% and 92.9% for 39 months of treatment with the vitamins/mineral and garlic preparation, respectively. The means for serum concentrations of vitamins C and E were 7.2 microg/ml and 1695 microg/dl among subjects in the active treatment groups compared with 3.1 microg/ml and 752 microg/dl among subjects in the placebo treatment group, respectively. No significant differences in side-effects were observed between the placebo treatment group and the vitamins/mineral and garlic preparation treatment groups during the 39-month trial period.

Adult↗
PubMed2001

Shear stress regulates occludin content and phosphorylation.

Previous studies determined that shear stress imposed on bovine aortic endothelial cell (BAEC) monolayers increased the hydraulic conductivity (L(P)); however, the mechanism by which shear stress increases L(P) remains unknown. This study tested the hypothesis that shear stress regulates paracellular transport by altering the expression and phosphorylation state of the tight junction protein occludin. The effect of shear stress on occludin content was examined by Western blot analysis. Ten dyn/cm(2) significantly reduced occludin content in a time-dependent manner such that after a 3 h exposure to shear, occludin content decreased to 44% of control. Twenty dyn/cm(2) decreased occludin content to 50% of control and increased L(P) by 4.7-fold after 3 h. Occludin expression and L(P) depend on tyrosine kinase activity because erbstatin A (10 microM) attenuated both the shear-induced decrease in occludin content and increase in L(P). Shear stress increased occludin phosphorylation after 5 min, 15 min, and 3 h exposures. The shear-induced increase in occludin phosphorylation was attenuated with dibutyryl (DB) cAMP (1 mM), a reagent previously shown to reverse the shear-induced increase in L(P). We conclude that shear stress rapidly (< or = 5 min) increases occludin phosphorylation and significantly decreases the expression of occludin over 1-4 h. Alterations in the occludin phosphorylation state and occludin total content are potential mechanisms by which shear stress increases L(P).

Animals↗
PubMed2001

7-Nitroindazole, but not aminoguanidine, attenuates the acute inflammatory responses and brain injury during the early phase of Escherichia coli meningitis in the newborn piglet.

We evaluated the anti-inflammatory and neuroprotective effects of the selective neuronal nitric oxide synthase inhibitor 7-nitroindazole and aminoguanidine, which predominantly inhibits inducible nitric oxide synthase, during the early phase of experimental bacterial meningitis in the newborn piglet. Meningitis was induced by intracisternal injection of 10(8) colony-forming units of Escherichia coli in 100 microl of saline. 7-Nitroindazole significantly attenuated the meningitis-induced acute inflammatory responses such as increased intracranial pressure, decreased cerebrospinal fluid (CSF) glucose concentration, and CSF leukocytosis at 2 h. However, meningitis-induced CSF leukocytosis at 4 h and increased CSF lactate and tumor necrosis factor alpha levels were not significantly attenuated. Reduced cerebral cortical cell membrane Na(+),K(+)-ATPase activity and increased lipid peroxidation products, indicative of meningitis-induced brain cell membrane dysfunction, were also significantly improved with 7-nitroindazole treatment. In contrast, although aminoguanidine significantly attenuated the increase in the CSF tumor necrosis factor alpha level, it failed to attenuate the acute inflammation and the ensuing brain injury in bacterial meningitis. In summary, 7-nitroindazole, but not aminoguanidine, significantly attenuated the acute inflammatory responses and brain injury during the early phase of neonatal bacterial meningitis.

Animals↗
PubMed2001

3-Aminobenzamide, a poly (ADP-ribose) synthetase inhibitor, attenuates the acute inflammatory responses and brain injury in experimental Escherichia coli meningitis in the newborn piglet.

The aim of the present study was to evaluate the anti-inflammatory and neuroprotective effects of a poly (ADP-ribose) synthetase inhibitor 3-aminobenzamide during the early phase of experimental bacterial meningitis in the newborn piglet. Meningitis was induced by intracisternal injection of 10(8) colony forming units of Escherichia coli in 100 microl of saline. 3-Aminobenzamide, given 30 mg kg(-1) as a bolus i.v. injection 30 min before induction of meningitis, significantly attenuated the meningitis-induced acute inflammatory responses such as increased cerebrospinal fluid (CSF) lactate concentration, CSF leukocytosis and increased CSF tumor necrosis factor-alpha level. However, meningitis-induced increase in intracranial pressure and decrease in CSF glucose level were not significantly improved. Increased cerebral cortical cell membrane lipid peroxidation products (conjugated dienes) and decreased brain ATP/phosphocreatine levels observed in the meningitis group were also significantly improved with 3-aminobenzamide treatment. However, the improvement of reduced Na+, K+-ATPase activity did not reach a statistical significance (p = 0.06). In summary, 3-aminobenzamide significantly attenuated the acute inflammatory responses and the ensuing brain injury during the early phase of neonatal bacterial meningitis. These findings suggest that poly (ADP-ribose) synthetase inhibitors such as 3-aminobenzamide might be a promising novel anti-inflammatory and neuroprotective adjuvant therapy in neonatal bacterial meningitis.

Acute Disease↗
PubMed2001

N(omega) -nitro-L-arginine methyl ester (L-NAME) attenuates the acute inflammatory responses and brain injury during the early phase of experimental Escherichia coli meningitis in the newborn piglet.

We evaluated the anti-inflammatory and neuroprotective effect of nonselective NOS inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME), in experimental bacterial meningitis in the newborn piglet. Meningitis was induced by intracisternal injection of 10(8) colony forming units of Escherichia coli. L-NAME 10 mg kg(-1) was given intravenously 30 min before induction of meningitis. L-NAME significantly attenuated the increase in intracranial pressure and decrease in cerebrospinal fluid glucose concentration observed in the meningitis group. Systemic and cerebral perfusion pressure were even higher compared to the control and meningitis groups. However, the meningitis-induced increase in tumor necrosis factor-alpha level, leukocyte numbers and lactate level in the cerebrospinal fluid was not significantly attenuated with L-NAME administration. Reduced cerebral cortical cell membrane Na+, K+ -ATPase activity and increased lipid peroxidation products, indicative of meningitis-induced brain cell membrane dysfunction, were significantly improved with L-NAME treatment. Decreased brain glucose and ATP levels were also significantly improved with L-NAME treatment. These findings suggest that L-NAME was effective in attenuating the acute inflammatory responses and brain injury in neonatal bacterial meningitis.

Animals↗
PubMed2001

Changes in dead space/tidal volume ratio and pulmonary mechanics after surfactant replacement therapy in respiratory distress syndrome of the newborn infants.

This study was performed to elucidate the mechanism of improved oxygenation after surfactant replacement therapy in respiratory distress syndrome (RDS) of the newborn infants. In 26 newborns with RDS, end tidal-CO2 tension (PetCO2), arterial blood gas analysis and pulmonary function tests were measured at baseline, 30 min, 2 hr and 6 hr after surfactant administration. The changes in dead space/tidal volume ratio (VD/VT ratio=(PaCO2-PetCO2)/PaCO2), oxygenation index and arterial-alveolar partial pressure difference for oxygen ((A-a)DO2) were elucidated and correlated with pulmonary mechanics. Oxygenation index and (A-a)DO2 improved, and VD/VT ratio decreased progressively after surfactant administration, becoming significantly different from the baseline at 30 min and thereafter with administration of surfactant. Pulmonary mechanics did not change significantly during the observation period. VD/VT ratio showed close correlation with OI and (A-a)DO2, but not with pulmonary mechanics. These results suggest that decreased physiologic dead space resulting from the recruitment of atelectatic alveoli rather than improvement in pulmonary mechanics is primarily responsible for the improved oxygenation after surfactant therapy in the RDS of newborn.

Airway Resistance↗
PubMed2001

Juxtaglomerular cell tumor of the kidney: a case report.

We report a case of renin-secreting juxtaglomerular cell tumor which developed in a hypertensive 47-yr-old Korean man. Presumptive clinical diagnosis was made before surgery based on the high level of plasma renin and the radiologic evidence of renal mass. Grossly, a round, bulging, well-encapsulated mass of 3 x 3 cm was located in the mid-portion of the right kidney. On microscopic examination, the tumor was composed of ovoid to polyhedral cells with bland nuclei, indistinct nucleoli and light eosinophilic cytoplasm. The immunostaining for renin showed strong positivity in the cytoplasm of tumor cells. The characteristic rhomboid shaped renin protogranules were observed in ultrastructural analysis.

Humans↗
PubMed2001

Effect of hypothermia on brain cell membrane function and energy metabolism after transient global hypoxia-ischemia in the newborn piglet.

This study was done to determine the effects of hypothermia on brain cell membrane function and energy metabolism after transient hypoxia-ischemia (HI) in the newborn piglet. Cerebral HI was induced by temporarily complete occlusion of bilateral common carotid arteries with surgical clips and simultaneous breathing with 8% oxygen for 30 min, followed by release of carotid occlusion and normoxic ventilation for 4 hr. Rectal temperature was maintained between 38.0 and 39.0 degrees C in normothermic groups, and between 34.0 and 35.0 degrees C in hypothermic groups for 4 hr after HI. During HI, heart rate, glucose and lactate level in the blood and cerebrospinal fluid increased, and base excess, pH and blood pressure decreased significantly in both normothermic and hypothermic groups. After HI, these abnormalities returned to normal in normothermic group, but lactic acidosis persisted in hypothermic group. Decreased cerebral Na+,K+- ATPase activity and increased lipid peroxidation products, indicative of HI- induced brain injury, were more profound in hypothermic group than in normothermic group. Brain ATP and phosphocreatine levels were not different between normothermic and hypothermic groups. In summary, hypothermia applied immediately after HI for 4 hr did not improve the recovery of brain cell membrane function and energy metabolism in the newborn piglet.

Animals↗
PubMed2001

Clinical significance of anti-endothelial cell antibody in renal transplant recipients.

In order to evaluate the role of anti-endothelial cell antibody (AECA) in acute rejection in renal transplantation, serum AECA IgG titers were measured in 68 healthy controls, 111 chronic hemodialysis (HD) patients and 58 first renal transplant recipients. The AECA titer in hemodialysis patients was higher than in healthy controls (13.9 +/- 5.0 vs. 4.8 +/- 2.3 U/mL, p < 0.01). In transplant recipients, AECA titers were not affected by dialysis mode (HD vs. CAPD vs. non-dialysis; 9.6 +/- 7.6 vs. 7.9 +/- 3.9 vs. 11.9 +/- 3.1 U/mL, p > 0.05). After renal transplantation, AECA titer was decreased significantly (vs. 4.7 +/- 3.6 U/mL. p < 0.01). The serum AECA IgG titers increased significantly in recipients with acute rejection (6.9 +/- 3.1 vs. 13.5 +/- 9.9 U/mL, p < 0.01), but decreased to 5.6 +/- 3.0 U/mL (p < 0.01) after formal rejection therapy. In the recipients with acute rejection (n = 27), the pre-renal transplant AECA titer was higher than in that without acute rejection (14.0 +/- 8.6 vs. 7.7 +/- 3.8 U/mL, p < 0.01). The results of this study lead us to conclude that pre- and post-renal transplant AECA titer might be a useful predictor for acute rejection and useful for monitoring acute rejection in renal transplant recipients.

Adult↗
PubMed2001

A case of hereditary angioedema associated with idiopathic hypoparathyroidism.

Hereditary angioedema is a rare autosomal dominant disease characterized by the edema of subcutaneous tissues, respiratory tract and bowel. It is caused by the deficiency of C1 esterase inhibitor. Hereditary angioedema may be associated with autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, autoimmune thyroiditis and glomerulonephritis. We report a 34-year-old male patient with hereditary angioedema who developed idiopathic hypoparathyroidism. Autoimmunity seems to be an important basis of this association and it might be caused by the immune dysfunction due to decreased level of complements; nevertheless, a casual association could not be excluded. To our knowledge, this is the first report of hereditary angioedema in association with idiopathic hypoparathyroidism in the medical literature.

Adult↗
PubMed2001

[Fudenine, relative to blood glucose-control, is a novel membrane protein].

OBJECTIVE: To determine whether Fudenine is a novel membrane protein. METHODS: Green fluorescence protein(GFP) was used to localize Fudenine in vivo. GFP, as a control, was targeted to cytoplasm. Epithelial cell, CBRH7919, and non-epithelial cell, L-6TG, were cultured and transiently transfected by using the lipofectamine reagent. After 48 h, intact cells were examined with fluorescence microscope for Fudenine. RESULTS: Reporter plasmid pEGFP-N1, as a control, was expressed and localized to cytoplasm. But Fudenine, driven by the cytomegalovirus promoterenhancer contained in the pEGFP-N1 vector, was overexpressed and targeted to cellular membrane. CONCLUSIONS: Fudenine is a novel membrane protein. It may play the similar role with its homologues AC133 antigen and prominin in human and mouse, respectively. It might be involved in signaling transduction and regulate blood glucose metabolism in vivo.

AC133 Antigen↗
PubMed2000

Mosaic blood vessels in tumors: frequency of cancer cells in contact with flowing blood.

The presence of "mosaic" vessels in which both endothelial cells and tumor cells form the luminal surface has profound implications for metastasis, drug delivery, and antivascular therapy. Yet little is known of the frequency, and thus importance, of mosaic vessels in tumors. Using CD31 and CD105 to identify endothelial cells and endogenous green fluorescent protein labeling of tumor cells, we show that approximately 15% of perfused vessels of a colon carcinoma xenografted at two different sites in mice were mosaic vessels having focal regions where no CD31/CD105 immunoreactivity was detected and tumor cells appeared to contact the vessel lumen. These regions occupied approximately 25% of the perimeter of the mosaic vessels, or approximately 4% of the total vascular surface area in these colon carcinomas. In addition, we found similar numbers of mosaic vessels in human colon carcinoma biopsies. Our results are consistent with the observation that approximately 10(6) cells are shed daily per g of tumor. More importantly, our data offer a possible explanation for the antivascular effects of cytotoxic agents and suggest potential strategies for targeting the tumor vasculature.

Animals↗