Biomedical subjects

J H Hwang

Publications and source records attributed to J H Hwang.

At least 73 records · Page 4Linked to original sources

PubMed1998

Factors affecting transformation efficiency of BCG with a Mycobacterium-Escherichia coli shuttle vector pYUB18 by electroporation.

BCG has been one of the vehicles for multi-recombinant vaccine. However, low transformation efficiency of BCG with plasmid DNA hampered studies involving expression of foreign antigens in BCG. In an effort to determine the optimal conditions, this study was initiated to investigate factors involved in the transformation of BCG with a Mycobacterium-Escherichia coli shuttle vector, pYUB18, by electroporation. Mycobacterium bovis BCG (strain 1173P2) was grown in Middlebrook (M) 7H9 broth containing albumin-dextrose-catalase and 0.05% tween 80, and transformed BCG was grown in M7H10 agar containing kanamycin for counting viable cells. Pretreatment of BCG with 10 mM CaCl2 improved the transformation efficiency, but overnight incubation of BCG with 1% glycine did not. The transformation efficiency in BCG also varied depending on voltage, resistance, and DNA concentration. The maximum transformation efficiency was obtained when the infinity resistance, 12.5 Kv/cm, and 100 ng of DNA were used, and reached 1.4 x 10(5) CFU/microgram of plasmid DNA, which is about 3-100 times greater than those from previous reports. The transformation conditions described in this study, therefore, will give us a better position for employing BCG as a vehicle for developing multi-recombinant vaccines.

Calcium Chloride↗

PubMed1998

Proton MR spectroscopic characteristics of pediatric pilocytic astrocytomas.

PURPOSE: We report the common characteristics of juvenile pilocytic astrocytomas revealed by proton MR spectroscopy. METHODS: Eight children with pilocytic astrocytomas were studied with proton MR spectroscopy. The selected sampling volume was approximately 4 cm3, obtained from solid tumor. To localize the sampling volume, we used point-resolved spectroscopy (PRESS) and stimulated-echo acquisition mode (STEAM) techniques to acquire long- and short-TE spectra, respectively. Spectra from PRESS and STEAM sequences were processed using Lorentzian-to-Gaussian transformation and exponential apodization, respectively. For PRESS (2000/270) spectra, peaks of creatine, choline, N-acetylaspartate (NAA), and lactate resonances were integrated; for STEAM (2000/20) spectra, we measured the amplitude of the peaks at 3.2, 2.0, 1.3 and 0.9 ppm. RESULTS: An elevated lactate doublet was observed in the PRESS spectra. The choline/NAA ratio was 3.40. The amplitude ratios of the lipid pattern (0.9, 1.3 and 2.0 ppm) to choline were all below one. CONCLUSION: Despite the benign histology of the tumor, which generally lacks necrosis, a lactate signal was detected in all eight patients studied. A dominant lipid pattern was not observed.

Aspartic Acid↗

PubMed1998

Excision of subcutaneous tissue and deep muscle fascia for advanced lymphedema.

In advanced peripheral lymphedema particularly involving the legs, complex physical therapy (massage/bandage-wrapping compression, remedial exercises, and maintenance use of a low stretch elastic compression garment), is not uniformly successful. In six patients with morbid lymphedema of the legs, we described our positive experience using a modified Auchincloss/Homans excisional operation.

Adipose Tissue↗

PubMed1997

Hepatitis C virus E2 protein purified from mammalian cells is frequently recognized by E2-specific antibodies in patient sera.

The envelope protein of hepatitis C virus (HCV) is composed of two membrane-associated glycoproteins, E1 and E2. To obtain HCV E2 protein as a secretory form at a high level, we constructed a recombinant chinese hamster ovary (CHO) cell line expressing a C-terminal truncated E2 (E2t) fused to human growth hormone (hGH), CHO/hGHE2t. The hGHE2t fusion protein was purified from the culture supernatant using anti-hGH mAb affinity chromatography at approximately 80% purity. The purified hGHE2t protein appeared to be assembled into oligomers linked by intermolecular disulfide bond(s) when density gradient centrifugation and SDS-polyacrylamide gel electrophoresis were employed. When the purified fusion protein was used for testing its ability to bind to antibodies specific for HCV by enzyme-linked immunosorbent assay, the protein was recognized by antibodies in sera from 90% of HCV-positive patients. Treatment of hGHE2t protein by beta-mercaptoethanol, but not by heat and SDS, significantly reduced its reactivity to the antibodies of patient sera, suggesting that intermolecular and/or intramolecular disulfide bonds are important for its ability to recognize its specific antibody and that the E2 protein contains discontinuous antigenic epitope(s).

Animals↗

PubMed1997

The effect of spinal GABA receptor agonists on tactile allodynia in a surgically-induced neuropathic pain model in the rat.

This study evaluated the effects of spinal gamma-aminobutyric acid (GABA) receptor agonists on the tactile allodynia observed in rats with ligation of the L5/L6 nerve roots (Chung model) and chronic lumbar intrathecal catheters. In these rats, the spinal injection of the GABAB agonist baclofen (BAC; 0.03-03 micrograms) and GABAA agonist muscimol (MUS; 0.1-1.0 micrograms) resulted in a dose-dependent antagonism of the allodynia at doses which had no detectable effect upon motor function. Intrathecal injection of the GABAB antagonist CGP 35348 (CGP; 30 micrograms) or the GABAA antagonist bicuculline (BIC; 0.3 micrograms) prior to injection of each GABA receptor agonist had little effect upon normal or tactile allodynic thresholds, but significantly reversed the anti-allodynic effects produced by the respective receptor agonists. The antagonistic effects were limited to the agonist of the respective receptor. These observations indicate that spinal GABAA and GABAB receptors modulate spinal systems activated by low threshold mechanoreceptors which mediate the allodynia observed following peripheral nerve injury.

Animals↗

PubMed1997

GM-CSF production by epithelial cell line: upregulation by ultraviolet A.

It was demonstrated that UVB increases synthesis and expression of IL-1 alpha and GM-CSF by keratinocytes. Upregulation of GM-CSF by UVB is reported to be mediated by IL-1 alpha. However, regulation of IL-1 alpha and GM-CSF by UVA is not well-known. The purpose of the present study was to evaluate the effects of UVA on IL-1 alpha and GM-CSF production. Here we used a competitive RT-PCR for measuring cytokine gene expression in an epidermal cell line after UVA irradiation. IL-1 alpha and GM-CSF mRNA did not show any change at 1 h and 6 h following exposure to UVA. After UVA irradiation, however, IL-1 alpha mRNA decreased and GM-CSF mRNA increased at 24 h and the level of GM-CSF in culture supernatant increased at 24 h and 48 h. Addition of antihuman IL-1 alpha neutralizing antibody to UVA irradiated cells did not prevent the increase of GM-CSF mRNA expression. These results suggest that UVA radiation may induce GM-CSF production through an IL-1 alpha independent pathway.

Antibodies↗

PubMed1997

P53 overexpression in gastric adenocarcinoma with Helicobacter pylori infection.

Gastric carcinogenesis has been studied in various aspects. Helicobacter pylori (Hp) infection and mutation of the p53 tumor suppressor gene have recently been argued to be important factors of gastric carcinogenesis. There have been many studies to determine the precise mechanism of how Hp is related to gastric cancer, but it is so far still unknown. We studied the relationship of Hp infection and p53 overexpression and tried to discover some significance in clinicopathologic factors such as age, sex, stage, site, differentiation and gross morphology. Ninety-six patients who were diagnosed with gastric cancer at Severance Hospital, Yonsei University Medical College from November 1995 to March 1996, and 96 control patients of non-ulcer dyspepsia (NUD) were studied by endoscopic biopsy of normal gastric tissue and cancer tissue. They also underwent the CLO (Delta West, Melbourne, Western Australia) test for Hp positivity and p53 immunohistochemical stain for p53 positivity. These data were analyzed for comparison with the clinicopathologic characteristics of gastric cancers. In conclusion, the differentiated group cancer had a significantly high Hp positivity and p53 positivity. There is a possibility that Hp infection and p53 tumor suppressor gene mutation might be significantly related in the gastric carcinogenic process of well- and moderately-differentiated adenocarcinomas, but further study is necessary to determine more direct clues on the carcinogenic roles of these factors.

Adenocarcinoma↗

PubMed1996

Impaired hepatic glycogen synthesis in glucokinase-deficient (MODY-2) subjects.

All glucokinase gene mutations identified to date have been localized to exons that are common to the pancreatic and hepatic isoforms of the enzyme. While impaired insulin secretion has been observed in glucokinase-deficient subjects the consequences of this mutation on hepatic glucose metabolism remain unknown. To examine this question hepatic glycogen concentration was measured in seven glucokinase-deficient subjects with normal glycosylated hemoglobin and 12 control subjects using 13C nuclear magnetic spectroscopy during a day in which three isocaloric mixed meals were ingested. The relative fluxes of the direct and indirect pathways of hepatic glycogen synthesis were also assessed using [1-13C]glucose in combination with acetaminophen to noninvasively sample the hepatic UDP-glucose pool. Average fasting hepatic glycogen content was similar in glucokinase-deficient and control subjects (279+/-20 vs 284+/-14 mM; mean+/-SEM), and increased in both groups after the meals with a continuous pattern throughout the day. However, the net increment in hepatic glycogen content after each meal was 30-60% lower in glucokinase-deficient than in the control subjects (breakfast, 46% lower, P < 0.02; lunch, 62% lower, P = 0.002; dinner; 30% lower, P = 0.04). The net increment over basal values 4 h after dinner was 105 +/-18 mM in glucokinase-deficient and 148+/-11 mM in control subjects (P = 0.04). In the 4 h after breakfast, flux through the gluconeogenic pathway relative to the direct pathway of hepatic glycogen synthesis was higher in glucokinase-deficient than in control subjects (50+/-2% vs 34+/-5%; P = 0.038). In conclusion glucokinase-deficient subjects have decreased net accumulation of hepatic glycogen and relatively augmented hepatic gluconeogenesis after meals. These results suggest that in addition to the altered beta cell function, abnormalities in liver glycogen metabolism play an important role in the pathogenesis of hyperglycemia in patients with glucokinase-deficient maturity onset diabetes of young.

Adult↗

PubMed1996

The roles of insulin and glucagon in the regulation of hepatic glycogen synthesis and turnover in humans.

To determine the respective roles of insulin and glucagon for hepatic glycogen synthesis and turnover, hyperglycemic clamps were performed with somatostatin [0.1 micrograms/(kg.min)] in healthy young men under conditions of: (I) basal fasting) portal vein insulinemia-hypoglucagonemia, (II) basal portal vein insulinemia-basal glucagonemia, and (III) basal peripheral insulinemia-hypoglucagonemia. Synthetic rates, pathway (direct versus indirect) contributions, and percent turnover of hepatic glycogen were assessed by in vivo 13C nuclear magnetic resonance spectroscopy during [1-13C]glucose infusion followed by a natural abundance glucose chase in conjunction with acetaminophen to noninvasively sample the hepatic UDP-glucose pool. In the presence of hyperglycemia (10.4 +/- 0.1 mM) and basal portal vein insulinemia (192 +/- 6 pM), suppression of glucagon secretion (plasma glucagon, I:31 +/- 4, II: 63 +/- 8 pg/ml) doubled the hepatic accumulation of glycogen (Vsyn) compared with conditions of basal glucagonemia [I: 0.40 +/- 0.06, II: 0.19 +/- 0.03 mumol/(liter.min): P < 0.0025]. Glycogen turnover was markedly reduced (I: 19 +/- 7%, II: 69 +/- 12%; P < 0.005), so that net rate of glycogen synthesis increased approximately fivefold (P < 0.001) by inhibition of glucagon secretion. The relative contribution of gluconeogenesis (indirect pathway) to glycogen synthesis was lower during hypoglucagonemia (42 +/- 6%) than during basal glucagonemia (54 +/- 5%; P < 0.005). Under conditions of basal peripheral insulinemia (54 +/- 2 pM) and hypoglucagonemia (III) there was negligible hepatic glycogen synthesis and turnover. In conclusion, small changes in portal vein concentrations of insulin and glucagon independently affect hepatic glycogen synthesis and turnover. Inhibition of glucagon secretion under conditions of hyperglycemia and basal concentrations of insulin results in: (a) twofold increase in rate of hepatic glycogen synthesis, (b) reduction of glycogen turnover by approximately 73%, and (c) augmented percent contribution of the direct pathway to glycogen synthesis compared with conditions of basal glucagonemia.

Adult↗

PubMed1996

Short echo time proton magnetic resonance spectroscopic imaging of macromolecule and metabolite signal intensities in the human brain.

A novel approach is presented for imaging macromolecule and metabolite signals in brain by proton magnetic resonance spectroscopic imaging. The method differentiates between metabolites and macromolecules by T1 weighting using an inversion pulse followed by a variable inversion recovery time before localization and spectroscopic imaging. In healthy subjects, the major macromolecule resonances at 2.05 and 0.9 ppm were mapped at a nominal spatial resolution of 1 x 1 x 1.5 cm3 and were demonstrated to be highly reproducible between subjects. In subacute stroke patients, a highly elevated macromolecule resonance at 1.3 ppm was mapped to infarcted brain regions, suggesting potential applications for studying pathological conditions.

Adult↗

PubMed1995

Impaired net hepatic glycogen synthesis in insulin-dependent diabetic subjects during mixed meal ingestion. A 13C nuclear magnetic resonance spectroscopy study.

Hepatic glycogen concentration was measured in six subjects with insulin-dependent diabetes mellitus (IDDM) and nine weight-matched control subjects using 13C nuclear magnetic resonance spectroscopy during a day in which three isocaloric mixed meals were ingested. The relative fluxes of the direct and indirect (3 carbon units-->-->glycogen) pathways of hepatic glycogen synthesis were also assessed using [1-13C]glucose in combination with acetaminophen to noninvasively sample the hepatic UDP-glucose pool. Mean fasting hepatic glycogen content was similar in the two groups. After each meal, hepatic glycogen content increased, peaking 4-5 h after the meal in both groups. By 11:00 p.m. the IDDM subjects had synthesized only 30% of the glycogen that was synthesized by the control group [IDDM subjects, net increment = 44 +/- 20 (mean +/- SE) mM; control subjects, net increment = 144 +/- 14 mM; P < 0.05]. After breakfast the flux through the gluconeogenic pathway relative to the direct pathway of hepatic glycogen synthesis was 1.7-fold greater in the IDDM subjects (59 +/- 4%) than in the control subjects (35 +/- 4%, P < 0.0003). In conclusion, under mixed meal conditions, subjects with poorly controlled IDDM have a major defect in net hepatic glycogen synthesis and augmented hepatic gluconeogenesis. The former abnormality may result in an impaired glycemic response to counterregulatory hormones, whereas both abnormalities may contribute to postprandial hyperglycemia.

Adult↗

PubMed1994

Functional analysis of the 14 kDa protein of insertion sequence 2.

The IS2 sequence encodes five open reading frames (ORF1 to ORF5) that are greater than 150 nucleotides each. Only one protein of 14 kDa was detected when the expression of IS2 genes was examined in minicells. This 14 kDa protein was referred to as InsA in this study and was determined to be encoded by ORF1. A sixfold decrease in IS2 transposition frequency was observed when insA was overexpressed. DNA footprinting results indicated that InsA binds to the sequence 5'-TAAATAA-3' located at IS2 nucleotide numbers 1286 to 1292. (The IS2 right terminal repeat spans nucleotides 1290 to 1331.) This InsA binding sequence is situated 4 bp upstream from the putative "-10" sequence of the insA promoter that overlaps the right terminal repeat of IS2. The presence of a promoter located in this region was demonstrated by the ability of a DNA fragment containing the right terminal repeat to drive the expression of a promoterless lacZ gene. The transcription of insA was determined to start at the A residue located at nucleotide number 1268. With the same insA promoter-lacZ fusion construct, overexpression of insA in the same cell was found to decrease the beta-galactosidase activity. The results of this study suggest that InsA affects IS2 transposition by regulating the transcription of IS2 genes.

Bacterial Proteins↗

PubMed1994

Synchronous carotid endarterectomy and myocardial revascularization.

BACKGROUND: The management of the coexisting extracranial carotid and coronary disease is still controversial. We reviewed our experience in synchronous operation for both diseases in Veterans General Hospital-Taipei. METHODS: From Jan. 1988 to Nov. 1992, the synchronous carotid endarterectomy and myocardial revascularization were performed in nine patients with the mean age of 66.6 +/- 11 years. Five had symptomatic extracranial vascular disease or stabilized neurological deficits, and four had asymptomatic carotid bruits. Four had bilateral hemodynamically significant carotid stenosis. NYHA functional class III-IV was noted in three patients. Triple-vessel coronary disease was documented in 6 patients including one with left main lesion more than 50%. Eight had previous or recent myocardial infarction and four had moderate to severe left ventricular dysfunction noted on left ventriculography. RESULTS: All nine patients received unilateral carotid endarterectomy and a mean number of 2.8 distal anastomosis. Operative number of 2.8 distal anastomosis. Operative mortality within 30 days was zero and morbidity was noted in two patients. One patient was CVA and the other one was perioperative myocardial infarction. Late mortality occurred in previous two patients with morbidity. Late morbidity was mainly due to cardiac rather than neurological problems. CONCLUSIONS: If long-term natural history of coronary or carotid artery disease could be actually altered by surgery, a systemic evaluation for possible multifocal atherosclerosis is mandatory. By following a proposed guideline, synchronous operation is appropriate for a subgroup of patients with coexisting carotid and coronary artery disease.

Aged↗

PubMed1993

Solvate structures in water-methanol solutions of MRI contrast agents: electron spin echo envelope modulation in gadolinium chelates.

Electron Spin Echo Envelope Modulation (ESEEM) data are reported for three gadolinium (III) chelates, Gd-EDTA, Gd-DTPA, and Gd-TTHA, in frozen D2O/CH3OD glasses. This series includes Gd-DTPA, an MRI contrast agent that is in clinical use. Three-pulse electron spin echo modulation patterns can be modeled to yield geometrical information; e.g., distances and numbers of Gd+3-OD interactions. Interpreted by a spherical shell model, the data for Gd-TTHA are accounted for by Gd+3 surrounded by seven deuterons at an effective distance of 3.9 A. We attribute these deuterons to second-coordination sphere solvent molecules, since it is likely that Gd+3 is fully coordinated by a TTHA ligand. For analysis of ESEEM from Gd-EDTA and Gd-DTPA, the second-sphere structures of Gd-EDTA, Gd-DTPA, and Gd-TTHA are assumed equivalent. 2H-ESEEM from inner-sphere solvent molecules gives the effective distance between deuterons and Gd+3 to be approximately 2.7 A for the inner-sphere water in both EDTA and DTPA complexes. The results of simulations also give the isotropic hyperfine and quadrupole coupling constants for solvent deuterium in these systems. Possible sources of error in the determination of r and q by this method are discussed.

Chelating Agents↗

PubMed1993

Right gastroepiploic artery: an alternative arterial conduit for coronary artery bypass.

From September 1990 to February 1991, 15 cases of myocardial revascularization with the right gastroepiploic artery (RGEA) combined with arterial or venous grafts were performed at VGH-Taipei. All were males, ranging in age from 49 to 64 years (mean age 61.2 +/- 4.6 years). The mean number of distal anastmoses including vein grafts was 3.6 +/- 0.7 and the mean number of graft was 3.1 +/- 0.3 per patient. The mean aortic clamp time was 123.6 +/- 24.0 minutes and the mean cardiopulmonary bypass time was 176 +/- 35 minutes. There was one mortality (6.7%). The other 14 patients are alive without angina. Studied within 3 postoperative months, graft early patency was 100% (6/6) in GEA graft. GEA graft should be a third available arterial conduit for coronary artery bypass.

Aged↗

PubMed1992

A new autoperfusion technique for aortic reconstruction of suprarenal aortic aneurysm.

Visceral ischemia is a serious factor in the postoperative morbidity and mortality of suprarenal aortic reconstruction. We reported two patients of suprarenal aortic aneurysm involving visceral arteries, who received successful Dacron graft replacement by using Pruitt-Inahara balloon catheters as an autoperfusion for preservation of the visceral organs. No visceral organ ischemia occurred postoperatively except in patient 2 who had preoperative chronic renal failure and persistent renal failure after the operation. The renal function recovered gradually during the follow-up period. Both patients are doing well at the present time. The new autoperfusion technique can directly deliver normothermic blood from the arterial cannula at proximal aorta to the individual visceral arteries by using the balloon perfusion catheters. It is simple, safe, easily instituted and the used products are readily obtainable. It allows the surgeon to provide an effective protection of visceral organs for the suprarenal aortic reconstruction.

Aged↗

PubMed1992

Pseudoaneurysm of the profundus femoris artery resulting from chronic injury of internal fixation screw.

We present an unusual case of pseudoaneurysm of profundus femoris artery which formed after injury from internal fixation screw for intertrochanteric fracture 8 years before. The main clinical manifestation was progressively enlarged pulsating mass and mild intermittent claudication. We resected the pseudoaneurysm after ligating the vessel proximal and distal to the pseudoaneurysm and cut off the excessive tip of the screw. After operation, the recovery was uneventful and no problem of the limb viability was noted.

Aged↗

PubMedDate not supplied

Effect of subarachnoid gabapentin on tactile-evoked allodynia in a surgically induced neuropathic pain model in the rat.

BACKGROUND AND OBJECTIVES: Spinal gamma-aminobutyric acid (GABA) receptors have been shown to modulate post-nerve injury-induced allodynia. This study sought to examine the antiallodynic effects of a GABA analog gabapentin [1-(aminomethyl)cyclohexaneacetic acid], given by subarachnoid injection in a rat neuropathic pain model. METHODS: The rats were prepared with lumbar subarachnoid catheters, and allodynia was induced in rats by ligation of the L5-6 nerve roots (Chung model). RESULTS: Spinal injection of gabapentin resulted in a dose-dependent (10-1,000 microg) antagonism of the allodynia at doses that had no detectable effect on motor function. Subarachnoid injection of either the GABA A antagonist bicuculline (0.3 microg), or the GABA B antagonist CGP 35348 (30 microg) 5 minutes before or 60 minutes after injection of GABA receptor agonist did not reverse the antiallodynic effects produced by gabapentin. CONCLUSIONS: Gabapentin shows antiallodynic effect, but its mechanism is not known. The failure to reverse this effect by GABA A or B antagonists at doses that reverse the effects of the respective agonists suggests that gabapentin is involved in the modulation of spinal systems by mechanisms that do not involve either a GABA A or a GABA B site.

Acetates↗