Biomedical subjects

M H Hwang

Publications and source records attributed to M H Hwang.

At least 19 recordsLinked to original sources

PubMed2003

Treatment of metal-contaminated water and vertical distribution of metal precipitates in an upflow anaerobic bioreactor.

A lab-scale upflow anaerobic bioreactor filled with granular sludge and cow manure was operated for 140 days to determine the mechanism of metal removal and the vertical distribution of metal precipitates. Heavy metal ions were removed in the order of Cu2+, Cd2+, Zn2+, Fe2+ and Mn2+ with respect to the height in the reactor. The solid phase analysis showed that the heavy metals were mostly precipitated in the form of metal sulfides by sulfate reduction The contents of metal precipitates in the reactor were as follows: (i) Cd and Zn were highest in the bottom, (ii) Fe was highest at the low-middle layer, and (iii) Mn was increased with the height in the reactor. The vertical distribution of metal sulfides in the reactor was directly related to the solubility product (Ksp). Results obtained in this study suggest a feasibility of the application to separate precipitation metal-containing wastewater.

Bacteria, Anaerobic↗

PubMed2000

Grip and key pinch strength: norms for 15- to 22-year-old Chinese students.

BACKGROUND: Establishment of norms for hand strength is emerging worldwide and is both important and necessary in public health and hand surgery. The purpose of this study was to establish normative data for hand grip and key pinch strength for 15- to 22-year-old Chinese students. METHODS: The Jamar dynamometer was used to measure grip strength and the Jamar pinch gauge to measure key pinch strength. All subjects were free of disease or injury that might affect hand strength. All complementary factors such as age, sex, height, weight, dominant hand for writing and exercise were recorded. The influences of injury, exercise and living habits on the performance of hand strength were also examined. RESULTS: Out of a total of 2,982 students examined, there were nine men (0.39%) who used the left hand for writing, 143 men (6.27%) who used the left hand during exercise, two women (0.28%) who wrote with the left hand and 26 women (3.70%) who used the left hand during exercise. The mean grip and key pinch strength of the left hand was about 90% that of the right hand. The mean grip and key pinch strength of the women was about 60% that of men. CONCLUSIONS: A strong correlation between the right hand and the left hand in grip and key pinch strength was found. Whether nonanthropometric factors may affect hand strengths was explored as well.

Adolescent↗

PubMed1999

Characterization of the mouse Xpf DNA repair gene and differential expression during spermatogenesis.

The human XPF protein, an endonuclease subunit essential for DNA excision repair, may also function in homologous recombination. To investigate a possible link between mammalian XPF and recombination that occurs during meiosis, we isolated, characterized, and determined an expression profile for the mouse Xpf gene. The predicted mouse XPF protein, encoded by a 3.4-kb cDNA, contains 917 amino acids and is 86% identical to human XPF. Appreciable similarity also exists between mouse XPF and homologous proteins in budding yeast (Rad1), fission yeast (Rad16), and fruit fly (Mei-9), all of which have dual functions in excision repair and recombination. Sequence analysis of the 38.3-kb Xpf gene, localized to a region in proximal mouse chromosome 16, revealed greater than 72% identity to human XPF in 16 regions. Of these conserved elements, 11 were exons and 5 were noncoding sequence within introns. Xpf transcript and protein levels were specifically elevated in adult mouse testis. Moreover, increased levels of Xpf and Ercc1 mRNAs correlated with meiotic and early postmeiotic spermatogenic cells. These results support a distinct role for the XPF/ERCC1 junction-specific endonuclease during meiosis, most likely in the resolution of heteroduplex intermediates that arise during recombination.

Amino Acid Sequence↗

PubMed1999

Domain mapping of the DNA binding, endonuclease, and ERCC1 binding properties of the human DNA repair protein XPF.

During nucleotide excision repair, one of the two incisions necessary for removal of a broad spectrum of DNA adducts is made by the human XPF/ERCC1 protein complex. To characterize the biochemical function of XPF, we have expressed and purified the independent 104 kDa recombinant XPF protein from E. coli and determined that it is an endonuclease and can bind DNA in the absence of the ERCC1 subunit. Endonuclease activity was also identified in a stable 70 kDa proteolysis fragment of XPF obtained during protein expression, indicating an N-terminal catalytic domain. Sequence homology and secondary structure predictions indicated a second functional domain at the C-terminus of XPF. To investigate the significance of the two predicted domains, a series of XPF deletion fragments spanning the entire protein were designed and examined for DNA binding, endonuclease activity, and ERCC1 subunit binding. Our results indicate that the N-terminal 378 amino acids of XPF are capable of binding and hydrolyzing DNA, while the C-terminal 214 residues are capable of binding specifically to ERCC1. We propose that the N-terminal domain of XPF contributes to the junction-specific endonuclease activity observed during DNA repair and recombination events. In addition, evidence presented here suggests that the C-terminal domain of XPF is responsible for XPF/ERCC1 complex formation. A working model for the XPF protein is presented illustrating the function of XPF in the nucleotide excision pathway and depicting the two functional domains interacting with DNA and ERCC1.

Binding Sites↗

PubMed1999

Pain on injection of propofol: the mitigating influence of metoclopramide using different techniques.

BACKGROUND: Metoclopramide administered intravenously (i.v.) immediately before injection of propofol, after mixing with propofol, or after a rubber tourniquet for 1 min before propofol injection will reduce pain induced by propofol injection. In this study, these three different techniques in reducing propofol injection pain with metoclopramide were compared with lidocaine or saline to evaluate the most effective method in reducing propofol injection pain. METHODS: In a randomized, semi-double-blind treatment, 175 patients were included into this study. Patients in group A were pretreated with metoclopramide 10 mg i.v. before propofol (2 mg/kg) induction. Patients in group B were induced with a mixture of propofol and metoclopramide. Patients in group C were pretreated with metoclopramide i.v. with a rubber tourniquet on the arm for 1 min followed by propofol administration. Groups D and E were identical to group C except for the replacement of pretreatment with either lidocaine (40 mg) or saline, respectively. RESULTS: Groups A, C and D (with active pain prophylaxis) showed a significantly less incidence of pain than the saline control group (E) as propofol was injected. There was no significance difference between metoclopramide and lidocaine in reducing propofol injection pain using a tourniquet technique. The intensity of the propofol injection pain (verbal pain score) was stronger with saline as compared with the other groups. CONCLUSIONS: We conclude that i.v. retention of metoclopramide with tourniquet is as good as lidocaine and may be a useful alternative for reducing pain on propofol injection.

Adult↗

PubMed1998

Thoracoscopic T2-sympathetic block by clipping--a better and reversible operation for treatment of hyperhidrosis palmaris: experience with 326 cases.

Although thoracoscopic sympathectomy or sympathicotomy is the best treatment for hyperhidrosis palmaris, a new approach of clipping only without transection of T2-sympathetic trunk is just as effective. Aside from the guaranteed cure of hyperhidrosis, this new method has fewer complications and has the advantage of recovery of the sympathetic tone in the hands if the procedure is reversed by the removal of the clips. Between March 18 and September 30 of 1996, 326 patients (190 female and 136 male with a mean age of 20.5 years) underwent thoracoscopic T2-sympathetic block by clipping to treat hyperhidrosis. Good results and few complications were noted during follow up six months to one year postoperatively. Five of the 326 patients, all female, had the operation reversed because of intolerable compensatory sweating. Three recovered from the compensatory sweating within two months and had less palmar sweating than before their sympathetic block; the fourth achieved relief of compensatory sweating after nine months, and the fifth reported no improvement.

Adolescent↗

PubMed1998

The analgesic effect of fentanyl, morphine, meperidine, and lidocaine in the peripheral veins: a comparative study.

UNLABELLED: Using venous retention with a tourniquet (70 mm Hg), we performed a randomized, double-blind study to assess the efficacy of I.V. pretreatment with fentanyl, morphine, meperidine, or lidocaine in reducing propofol injection pain. Immediately after venous occlusion with a tourniquet, I.V. fentanyl 150 microg (Group A, n = 35), morphine 4 mg (Group B, n = 35), meperidine 40 mg (Group C, n = 35), 2% lidocaine 3 mL (Group D, n = 35), or normal saline 3 mL (Group E, n = 35; as placebo control) was given to adult patients. The venous retention of the drug was maintained for 1 min, followed by tourniquet release and I.V. administration of propofol 100 mg. Pain assessment was made immediately after the propofol injection. Lidocaine and meperidine significantly reduced propofol injection pain more than placebo (P < 0.05), but there were more side effects in the meperidine group. Fentanyl and morphine reduced the intensity of propofol injection pain (P < 0.05) and had some effect in reducing the incidence of propofol injection pain, but the difference did not reach statistical significance. The order of efficacy was lidocaine approximately meperidine > morphine approximately fentanyl. We postulate that the peripheral analgesic effect of these opioid is due to their local anesthetic activity. IMPLICATIONS: Propofol, a commonly used anesthetic, often causes pain on injection. Given as venous retention pretreatments 1 min before propofol, meperidine and lidocaine were found to significantly reduce the propofol injection pain, whereas fentanyl and morphine only slightly reduced the propofol injection pain.

Adult↗

PubMed1998

Application of spinal pain mapping in the diagnosis of low back pain--analysis of 104 cases.

BACKGROUND: Low back pain is probably the most common pain problem seen in a general pain clinic and the cause of low back pain can be enigmatic at times. Often the pain sources are difficult to identify with the conventional diagnostic modalities. Spinal pain mapping is a sequence of well organized nerve block procedures. We undertook this study to evaluate the usefulness of this modality in diagnosing low back pain of uncertain etiology. METHODS: In this prospective study, 104 consecutive adult patients who underwent spinal pain mapping were examined and analyzed. All patients had intractable low back pain of undetermined etiology after medical history, physical examination and 4-view roentgenographic evaluation of the lumbar spine had been undertaken to locate it. In addition, 41 patients (39%) had one or more of the following tests done, which included CT, MRI, EMG/NC but all failed to delineate the causes of the pain. All patients failed to respond to the conservative therapies. RESULTS: With pain mapping the source of pain was found to be caused by sacro-iliac joint in 6%, lumbar nerve root in 20%, facet joint in 24%, combined lumbar nerve root and facet disease in 24%, internal disc disorder in 7%, combined facet and sacro-iliac joint in 4% and lumbar sympathetic dystrophy in 2% of patients. Pain mapping failed to demonstrate the causes of the pain in the remaining 13% of the patients. CONCLUSIONS: Considering the difficult nature of this group of patients, spinal pain mapping provided a useful functional approach to the diagnosis of low back pain with obscure etiology in 87% of patients in our series.

Adult↗

PubMed1995

Cytotoxicity and antimicrobial activity of some naphthol derivatives.

2-Hydroxymethyl-1-naphthol diacetate (TAC) and sixteen Mannich base derivatives of naphthol were prepared and examined for cytotoxicity and antimicrobial activity. Cytotoxicity was examined against four human carcinoma cell lines. Several derivatives were effective at concentrations < 4 micrograms/ml. TAC showed the highest cytotoxicity. Inhibition of DNA-, RNA-, and protein synthesis by TAC was also studied and discussed. TAC also exhibits potent antimicrobial activity against Enterobacter clocae 23355, Klebsiella pneumonia 13883, Proteus vulgaris 13315, Pseudomonas aeruginosa 27853, Candida parapsilosis, Candida tropicalis, Trichosposon beigelli, and Rhodotorul spp. with minimum inhibitory concentrations of 0.1-0.4 microM. These results indicate that esterification by Bruson reaction of 1-naphthol Mannich base to TAC enhances the cytotoxicity and antimicrobial activity.

Anti-Bacterial Agents↗

PubMed1995

Effect of acute pericardial tamponade on the relative contributions of systolic and diastolic pulmonary venous return: a transesophageal pulsed Doppler study.

The effect of acute pericardial tamponade on pulmonary venous return was assessed by transesophageal pulsed Doppler echocardiography. In 14 open-chest anesthetized dogs peak pulmonary venous flow velocities in systole (VJ) and in diastole (VK) were measured during apnea and atrial pacing while acute tamponade was induced by intrapericardial instillation of 0.9% sodium chloride solution. Before intravascular volume expansion, induction of acute tamponade resulted in a significant decline in VK (43 +/- 17 to 19 +/- 8 cm/sec; p < 0.05) but no change in VJ or the ratio VJ/VK. After intravascular volume expansion, induction of acute tamponade resulted in significant reductions in VJ (43 +/- 9 to 29 +/- 10 cm/sec; p < 0.001) and VK (37 +/- 19 to 15 +/- 11 cm/sec; p < 0.001). The effect was disproportionately greater on VK, however, resulting in a significant increase in VJ/VK (1.51 +/- 0.84 to 2.58 +/- 1.41; p < 0.001). The disproportionate effect of acute tamponade on VK suggests that increased pericardial pressure directly constrains diastolic filling of the left atrium as a conduit to the left ventricle and that it does not decrease the systolic and diastolic phases of pulmonary venous return uniformly. Intravascular volume expansion increases cardiac output before acute tamponade, but during acute tamponade it amplifies the disproportionate impact of increased pericardial pressure on left ventricular diastolic filling as the left ventricle is constrained within the fluid-filled pericardial sac.

Acute Disease↗

PubMed1995

Effects of contrast media on coronary hemodynamics and myocardial metabolism.

RATIONALE AND OBJECTIVES: This study was designed to compare the effects of ionic contrast medium (CM), Renografin-76 (R76), and nonionic CM, Omnipaque-350 (OM350), on coronary hemodynamics and myocardial metabolism. METHODS: In 10 open-chest, atrial-paced dogs, 4 mL of R76 and OM350 were injected into the left anterior descending coronary artery. Coronary blood flow (CBF), myocardial oxygen consumption (MVO2), lactate extraction (LE), left ventricular (LV) dp/dt, and aortic systolic pressure (AOP) were measured. RESULTS: The maximal CBF changes caused by OM350 and R76 were 23.7 +/- 3.3 mL/minute and 18.3 +/- 3.3 mL/minute (NS), respectively. OM350 produced an increase in LV dp/dt by 378 +/- 85 mm Hg/second, which was different from -244 +/- 65 mm Hg/second by R76 (P < .05). The changes in MVO2 and LE after OM350 injection were 2.6 +/- 0.6 mL/minute and 10.2 +/- 5 microM/minute, respectively; those were different from -0.1 +/- 0.4 mL/minute, and -7.7 +/- 5.1 microM/minute after R76 injection (P < .05). CONCLUSION: Although both agents increased CBF, they appeared to act by different mechanisms. That a direct coronary vasodilator effect is the main action of R76 on coronary vascular response is suggested by decreasing myocardial contractility and oxygen consumption. However, OM350, by enhancing both parameters, may augment CBF at least in part by autoregulation.

Animals↗

PubMed1995

Ultrasound-guided percutaneous transhepatic gallbladder drainage followed by laparoscopic cholecystectomy: a new trial in the treatment of severe acute suppurative cholecystitis.

Seven cases of acute suppurative cholecystitis underwent percutaneous transhepatic gallbladder drainage followed by laparoscopic cholecystectomy at the Tainan Municipal Hospital. All the patients had frank septic phenomena clinically, including fever, jaundice, leukocytosis and unstable blood pressure. Organisms were cultured from both blood and bile specimens. Ultrasound-guided transhepatic puncture of the gallbladder was performed for bile drainage, and laparoscopic cholecystectomy was subsequently performed two to five days later after the patients had stabilized. No procedure-related complications from either percutaneous transhepatic gallbladder drainage or laparoscopic cholecystectomy were observed. All patients had early recovery, shortened hospital stay and good cosmetic results. These preliminary results show that laparoscopic cholecystectomy is a safe method and can be employed in those patients with symptomatic gallstone associated with suppurative cholecystitis after preoperative biliary drainage.

Acute Disease↗

PubMed1995

Pulmonary carcinoid tumor--tumorlet type: a case report.

A rare case of bronchiectasis with carcinoid tumor, tumorlet type, is reported. The patient was a 53-year-old female who underwent lobectomy of the right middle and lower lobes for severe hemorrhage secondary to bronchiectasis. No tumor was seen on chest X-ray or by gross examination of the lung. Microscopically, there were multiple tumorlets in the pulmonary parenchyma surrounding the bronchiole and small bronchus. The tumor cells stained positive for neuron-specific enolase, keratin and chromogranin stain. The morphology, and staining properties suggested that the pulmonary tumorlets were carcinoid tumor. No tumor cells were identified in the four peribronchial lymph nodes. The patient is disease-free after four years of follow-up.

Carcinoid Tumor↗

PubMed1994

Restenosis presented with unstable angina and myocardial infarction: one explanation for late cardiac events following directional coronary atherectomy.

Three cases of restenosis after directional coronary atherectomy (DCA) presented with unstable angina and then myocardial infarction. Two of them were complicated with malignant ventricular dysrhythmia. A total or subtotal thrombotic occlusion at the DCA site was shown. This fulminating course of restenosis could partially explain the higher late cardiac morbidity and mortality after DCA than after percutaneous transluminal balloon angioplasty.

Aged↗

PubMed1994

Impairment of myocardial vascular responsiveness after transient myocardial ischemia and reperfusion.

Coronary vascular responses after brief periods of myocardial ischemia are impaired. Whereas some studies suggest that the ischemic insult selectively depresses endothelium-dependent vasodilator mechanisms, other studies indicate that even responses to direct vascular smooth-muscle relaxants such as adenosine may be decreased. This study was undertaken to measure regional myocardial blood flow (RMBF) responses to adenosine (a direct coronary vasodilator) and serotonin (an indirect, endothelium-dependent vasodilator) in myocardium subjected to regional ischemia followed by reperfusion. Temporary regional ischemia was achieved by 20 minutes of occlusion of the left anterior descending coronary artery (LAD) followed by 20 minutes of reflow in 10 open-chest anesthetized dogs. In the left circumflex coronary artery (LCX) territory, which served as a nonischemic control, RMBF (measured with radioactive microspheres) increased significantly in response to left atrial infusions of adenosine (1.29 +/- 0.27 to 3.89 +/- 3.89 +/- 2.15 ml/min/gm; p < 0.001) and serotonin (1.29 +/- 0.27 to 3.29 +/- 1.49 ml/min/gm; p < 0.001) and the percent reduction in coronary vascular resistance (% delta CVR) was comparable for these two pharmacologic probes (65% +/- 26% vs 62% +/- 19%; difference not significant [NS]). In contrast, in the myocardium supplied by the LAD, which was subjected to ischemia followed by reperfusion, the augmentation of RMBF by adenosine (1.07 +/- 0.29 to 1.82 +/- 1.35 ml/min/gm; p < 0.001) and serotonin (1.07 +/- 0.29 to 2.37 +/- 1.21 ml/min/gm; p < 0.001) was blunted.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗

PubMed1994

Bilateral hepatic duct decompression via a single percutaneous tract using a 'mother-baby' drainage catheter.

Decompression of the right and left hepatic ducts using a 'mother-baby' self-made drainage system via a single percutaneous tract was performed successfully in 15 of 21 patients with benign (n = 4) and malignant (= 17) hilar obstruction. The 'mother-baby' drainage system was composed of an 18 F catheter placed through the right hepatic duct into the distal common bile duct which was designated as the 'mother' catheter, while a second 10 F baby catheter was placed through the first catheter into the left hepatic ducts. This was achieved by a three-stage procedure: (1) percutaneous transhepatic biliary drainage; (2) balloon dilatation of the tract; and (3) intubation of the contralateral hepatic duct and placement of the 'mother-baby' drainage catheters. The mean interval of stent clogging was 5 months, with a range of 2-9 months. In 12 malignant cases, average survival time was 9.8 months. The technique avoided a second percutaneous hepatic puncture in centrally obstructing lesions and afforded bilateral biliary decompression.

Aged↗

PubMed1994

The fracture, dislodgement and retrieval of a probe III balloon-on-a-wire catheter.

The fracture and dislodgement of an angioplasty device within the coronary arteries is a rare but increasingly noted complication. If the fragment of angioplasty balloon or guidewire is dislodged in a proximal and patent coronary artery, the likelihood of acute embolization which could lead to an acute coronary thrombus and/or myocardial infarction exists. Therefore, the immediate removal of the broken piece of the angioplasty catheter is imperative. A case of unusual fracture and dislodgement of a Probe III Balloon-on-A-Wire catheter and retrieval of the broken piece is reported.

Aged↗

PubMed1994

Intraoperative cardiac arrest: a rare complication of T2,3-sympathicotomy for treatment of hyperhidrosis palmaris. Two case reports.

Endoscopic surgery, including thoracoscopic sympathicotomy for treatment of hyperhidrosis, is thought to be safe and entail fewer complications as compared with open methods. A total of more than 719 patients with hyperhidrosis have undergone thoracoscopic T2,3-sympathicotomy for treatment of hyperhidrosis at Tainan Municipal Hospital since October 1, 1989. Most of the complications have been minor; however, two of the patients suffered from sudden cardiac arrest at the time when the left T2,3-sympathetic nerve trunk was transected by the thoracoscopic method. Vigorous cardiopulmonary resuscitation was performed and both patients recovered completely without any sequelae. The purpose of this paper was to discuss the possible mechanism of cardiac arrest in thoracoscopic sympathicotomy, and to emphasise this rare but potentially fatal complication in the treatment of hyperhidrosis palmaris.

Adolescent↗