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Abstract
BACKGROUND Serum eosinophil cationic protein (ECP) levels affect the surgical outcome of chronic rhinosinusitis (CRS) with nasal polyps. Primary CRS can be classified into type 2 (T2) and non-T2. We aimed to differentiate the role of serum ECP levels in surgical outcomes between the distinct endotypes of primary CRS. METHODS We prospectively enrolled patients with bilateral primary CRS who underwent surgical treatment with postoperative follow-up for at least 12 months. Endotyping and serum parameter measurements were completed within 1 week before surgery. RESULTS In total, 113 patients were enrolled, including 65 with T2 CRS and 48 with non-T2 CRS. Patients in the T2 CRS group with uncontrolled CRS had significantly higher serum ECP levels than those in patients in the non-T2 CRS group. An optimal cut-off value was obtained at 17.0 μg/L using the receiver operating characteristic curve, attaining a sensitivity of 91.7% and specificity of 56.6%. Multivariate logistic regression analysis showed that a higher serum ECP level was an independent factor for postoperative uncontrolled disease. The hazard ratio was 11.3 for the T2 group, with serum ECP levels over 17.0 μg/L. In the non-T2 group, no parameters were significantly correlated with postoperative uncontrolled CRS. CONCLUSIONS Serum ECP levels appear to be a feasible predictor of postoperative uncontrolled disease in patients with T2 CRS as preoperative serum ECP levels >17.0 μg/L in these patients have an approximately 16.7-fold increased risk of postoperative uncontrolled disease and should be closely monitored.
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Affiliation(s)
- P C Tsai
- Department of Otolaryngology, Head and Neck Surgery, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan
| | - T J Lee
- Department of Otolaryngology, Head and Neck Surgery, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan
| | - P H Chang
- Department of Otolaryngology, Head and Neck Surgery, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - C H Fu
- Department of Otolaryngology, Head and Neck Surgery, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
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Tsai PC, Liu YC, Li TS, Hsu FT, Lee YH, Chiang IT, Chang Y, Lee CH. Clinical Effect of Moisturized Skin Care on Radiation Dermatitis of Head and Neck Cancer. In Vivo 2023; 37:2776-2785. [PMID: 37905662 PMCID: PMC10621431 DOI: 10.21873/invivo.13389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/22/2023] [Accepted: 07/24/2023] [Indexed: 11/02/2023]
Abstract
BACKGROUND/AIM Radiation therapy (RT) for head and neck cancer may cause severe radiation dermatitis (RD) resulting in RT interruption and affecting disease control. A few studies address skin moisture changes during RT for head and neck cancer. The purpose of this study was to explore the effect of moisturized skin care (MSC) on severity of RD. PATIENTS AND METHODS The study includes newly diagnosed head and neck cancer patients undergoing RT. Participants were divided into MSC group and routine skin care (RSC) group based on patient's preferred decision. Skin moisture in the four quadrants of the neck was measured weekly before and after RT. RD was assessed with the Radiation Induced Skin Reaction Assessment Scale (RISRAS) and the Radiation Therapy Oncology Group (RTOG) acute skin toxicity grading criteria. RESULTS A total of 54 patients were enrolled, of which 49 patients were suitable for the statistical analysis. There was a statistically significant difference in the RISRAS total score since the 5th week after RT between the groups. The severity of RD was less (B=0.814, p=0.021) and the onset was later (B=-0.384, p=0.006) in the MSC group when compared to the RSC group. Skin moisture decreased with cumulative radiation dose. In the upper neck, the MSC group had a slower rate of skin moisture decrease compared to the RSC group (right upper neck: B=0.935, p=0.007; left upper neck: B=0.93, p=0.018). CONCLUSION MSC can effectively reduce the severity and delay the onset of RD, while slows down skin moisture decrease during RT.
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Affiliation(s)
- Pei-Chuan Tsai
- Center of Hyperbaric Oxygen Center and Wound Care, Chang Bing Show Chwan Memorial Hospital, Changhua, Taiwan, R.O.C
- Department of Nursing Chung Shan Medical University, Taichung, Taiwan, R.O.C
| | - Yu-Chang Liu
- Department of Radiation Oncology, Chang Bing Show Chwan Memorial Hospital, Lukang, Taiwan, R.O.C
- Department of Radiation Oncology, Show Chwan Memorial Hospital, Changhua, Taiwan, R.O.C
- Department of Medical Imaging and Radiologic Sciences, Central Taiwan University of Science and Technology, Taichung, Taiwan, R.O.C
| | - Tzong Shiun Li
- Department of Plastic Surgery, Chang Bing Show Chwan Memorial Hospital, Changhua, Taiwan, R.O.C
- Innovation Research Center, Show Chwan Health Care System, Changhua, Taiwan, R.O.C
| | - Fei-Ting Hsu
- Department of Biological Science and Technology, China Medical University, Taichung, Taiwan, R.O.C
| | - Yuan-Hao Lee
- Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan, R.O.C
| | - I-Tsang Chiang
- Department of Radiation Oncology, Chang Bing Show Chwan Memorial Hospital, Lukang, Taiwan, R.O.C
- Department of Radiation Oncology, Show Chwan Memorial Hospital, Changhua, Taiwan, R.O.C
- Department of Medical Imaging and Radiologic Sciences, Central Taiwan University of Science and Technology, Taichung, Taiwan, R.O.C
- Medical Administrative Center, Show Chwan Memorial Hospital, Changhua, Taiwan, R.O.C
| | - Yuan Chang
- Department of Radiology, Taipei Medical University-Shuang Ho Hospital, Ministry of Health and Welfare, New Taipei City, Taiwan, R.O.C
| | - Chiu-Hsiang Lee
- Department of Nursing Chung Shan Medical University, Taichung, Taiwan, R.O.C.;
- Department of Nursing Chung Shan Medical University Hospital, Taichung, Taiwan, R.O.C
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3
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Shih HA, Tsai PC, Wu KH, Chen YT, Chen YC. Bacteremia in cirrhotic patients with upper gastrointestinal bleeding. Turk J Gastroenterol 2018; 29:164-169. [PMID: 29749322 DOI: 10.5152/tjg.2018.17309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND/AIMS Increased risk of bacterial infection is common in cirrhotic patients with upper gastrointestinal bleeding (UGIB). Our study aimed to explore the association of the bacteremia with in-hospital mortality and risk factors of bacteremia in these patients. MATERIALS AND METHODS In our retrospective cohort study, we collected data for cirrhotic patients with UGIB admitted to our hospital between August 2010 and December 2010. The primary outcome was in-hospital mortality. The secondary outcome was bacteremia. A multivariate logistic regression analysis was performed to determine risk factors for mortality and bacteremia. RESULTS A total of 202 patients with cirrhosis presenting with UGIB at the emergency department (ED) were enrolled. Bacteremia was associated with a higher mortality rate (adjusted odds ratio [OR]: 9.7; 95% confidence interval [CI]: 1.9-50.6, p=0.007), whereas shock (systolic blood pressure <90 mmHg at ED triage) and bandemia (>0% immature neutrophils of band form) were associated with bacteremia in cirrhotic patients with UGIB (adjusted OR: 5.3; 95% CI: 2.3-12.7, p<0.0001 and adjusted OR: 4.0; 95% CI: 1.6-9.9, p=0.0003, respectively). CONCLUSION Bacteremia in cirrhotic patients with UGIB is one of the major risk factors leading to in-hospital mortality. On the basis of our findings, prevention of bacteremia in cirrhotic patients with UGIB, especially in those with shock and bandemia, is important; thus, adequate antibiotic treatment is suggested.
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Affiliation(s)
- Hsin-An Shih
- Department of Emergency Medicine, Chang Gung Memorial Hospital, Chiayi County, Taiwan
| | - Pei-Chuan Tsai
- Department of Emergency, Taichung Tzu Chi Hospital, Taichung City, Taiwan
| | - Kai-Hsiang Wu
- Department of Emergency Medicine, Chang Gung Memorial Hospital, Chiayi County, Taiwan
| | - Yi-Ting Chen
- Department of Obstetrics and Gynecology, Changhua Christian Hospital, Changhua County, Taiwan
| | - Yi-Chuan Chen
- Department of Emergency Medicine, Chang Gung Memorial Hospital, Chiayi County, Taiwan; Department of Nursing, Chang Gung University of Science and Technology, Chiayi County, Taiwan
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4
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Lin PY, Hsieh CW, Tsai PC, Hsieh S. Cover Picture: Porosity-Controlled Eggshell Membrane as 3D SERS-Active Substrate (ChemPhysChem 8/2014). Chemphyschem 2014. [DOI: 10.1002/cphc.201490035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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5
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Lin PY, Hsieh CW, Tsai PC, Hsieh S. Porosity-Controlled Eggshell Membrane as 3D SERS-Active Substrate. Chemphyschem 2014; 15:1577-80. [DOI: 10.1002/cphc.201301222] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Indexed: 11/09/2022]
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6
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Liao WC, Wu WH, Tsai PC, Wang HF, Liu YH, Chan CF. Kinetics of Ergothioneine Inhibition of Mushroom Tyrosinase. Appl Biochem Biotechnol 2011; 166:259-67. [DOI: 10.1007/s12010-011-9421-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 10/18/2011] [Indexed: 10/15/2022]
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7
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Hseu YC, Chen SC, Tsai PC, Chen CS, Lu FJ, Chang NW, Yang HL. Inhibition of cyclooxygenase-2 and induction of apoptosis in estrogen-nonresponsive breast cancer cells by Antrodia camphorata. Food Chem Toxicol 2006; 45:1107-15. [PMID: 17391824 DOI: 10.1016/j.fct.2006.12.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 12/06/2006] [Accepted: 12/12/2006] [Indexed: 01/16/2023]
Abstract
The objective of this study was to investigate the fermented culture broth of Antrodia camphorata (A. camphorata) to induce apoptosis and inhibit cyclooxygenase-2 (COX-2) in estrogen-nonresponsive (MDA-MB-231) human breast cancer cells. Treatment of the highly invasive MDA-MB-231 cells with A. camphorata (40-240 microg/ml) resulted in dose and time-dependent sequences of events marked by apoptosis, as evidenced by loss of cell viability, chromatin condensation, and internucleosomal DNA fragmentation. Apoptosis in the MDA-MB-231 cells was accompanied by release of cytochrome c, activation of caspase-3, -8, and -9, and specific proteolytic cleavage of poly (ADP-ribose) polymerase (PARP). Although the A. camphorata-induced apoptosis was associated with a reduction in Bcl-2 protein levels, negligible Bax increase was observed. Furthermore, A. camphorata treatment inhibited COX-2 protein expression and prostaglandin E2 (PGE2) production in MDA-MB-231 cells. Analysis of the study data suggests that A. camphorata exerts growth inhibition on (highly invasive) estrogen-nonresponsive human breast cancer cells through apoptosis induction associated with COX-2 inhibition, and that it may possess anticancer properties potentially valuable for application in drug products.
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Affiliation(s)
- You-Cheng Hseu
- Department of Cosmeceutics, China Medical University, Taichung, Taiwan
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8
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Yang HL, Chen SC, Chang NW, Chang JM, Lee ML, Tsai PC, Fu HH, Kao WW, Chiang HC, Wang HH, Hseu YC. Protection from oxidative damage using Bidens pilosa extracts in normal human erythrocytes. Food Chem Toxicol 2006; 44:1513-21. [PMID: 16765500 DOI: 10.1016/j.fct.2006.04.006] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 03/27/2006] [Accepted: 04/18/2006] [Indexed: 01/29/2023]
Abstract
Bidens pilosa (B. pilosa) is well known in Taiwan as a traditional Chinese medicine. The purpose of this study was to evaluate the ability of both the ethanol (EtOH) and ethylacetate/ethanol (EA/EtOH) extracts from the whole B. pilosa plant, to protect normal human erythrocytes against oxidative damage in vitro. It was determined that the oxidative hemolysis and lipid/protein peroxidation of erythrocytes induced by the aqueous peroxyl radical [2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)] were suppressed by both EtOH (50-150 microg/ml) and EA/EtOH (25-75 microg/ml) extracts of B. pilosa in concentration- and time-dependent manners. B. pilosa extracts also prevented the decline of superoxide dismutase (SOD) activity and the depletion of cytosolic glutathione (GSH) and ATP in erythrocytes. These results imply that B. pilosa may have protective antioxidant properties.
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Affiliation(s)
- Hsin-Ling Yang
- Institute of Nutrition, China Medical University, Taichung, Taiwan
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9
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Tsai PC, Ding WH. Determination of alkyltrimethylammonium surfactants in hair conditioners and fabric softeners by gas chromatography–mass spectrometry with electron-impact and chemical ionization. J Chromatogr A 2004; 1027:103-8. [PMID: 14971489 DOI: 10.1016/j.chroma.2003.10.047] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The commercial hair conditioners and fabric softeners were analyzed for the content of alkyltrimethylammonium compounds (ATMACs) by gas chromatography-mass spectrometry (GC-MS) with electron impact (EI) and low-pressure positive-ion chemical ionization (PICI) modes. The method involves mixed diluted samples (adjust pH to 10.0) with potassium iodide to enhance the extraction of iodide-ATMA+ ion pairs by direct liquid-liquid extraction. The iodide-ATMA+ pairs were then demethylated to their corresponding nonionic alkyldimethylamines (ADMAs) by thermal decomposition in a GC injection-port. A high abundance of ADMAs was detected at the temperature above 300 degrees C in the GC injection-port. The enhanced selectivity of quasi-molecular ion chromatograms of C12-C18-ADMA, obtained using methanol PICI-MS enables ADMAs to be identified. The accuracy and precision of the method was validated and was successfully applied to determine contents of ATMAC in commercial hair conditioners and fabric softeners. The contents of total measured ATMAC ranged from 0.4 to 6.9% for hair conditioners, and from 3.3 to 4.6% for fabric softeners.
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Affiliation(s)
- Pei-Chuan Tsai
- Department of Chemistry, National Central University, Chung-Li 32054, Taiwan
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10
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Tsai PC, Chang FC, Tsai CH, Jang FR, Shen AN, Huang YT, Lai SC, Yeh TH, Lu MK, Lu CS. Focal hand myoclonus caused by a small hematoma underneath the cerebral motor cortex. Eur Neurol 2003; 50:114-7. [PMID: 12944720 DOI: 10.1159/000072512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- P C Tsai
- Department of Neurology, Chang Gung Memorial Hospital, Taipei, Taiwan
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11
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Chan CP, Chang HC, Chen YL, Yang LH, Chen ST, Kuo SJ, Tsai PC. A 10-year experience of unsuspected gallbladder cancer after laparoscopic cholecystectomy. Int Surg 2003; 88:175-9. [PMID: 14584775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
Unsuspected gallbladder cancer after laparoscopic cholecystectomy (LC) is a cancer that was previously manipulated by laparoscopic technique. The reported incidence was 0.3-1% and became an emerging problem as the popularity of LC increased. Lack of reliable data could address the outcome of reresection or nonreresection patients and the standard management. This study reviewed a single center experience in managing unsuspected gallbladder cancer patients after LC between July 1, 1992 and July 1, 2000 who had at least 2 years of follow-up. There were 11 patients (0.6%) postoperatively diagnosed with gallbladder cancer after 1825 LCs. Group A included three patients (28%) with nontransmural invasion, group B included four patients (36%) who had transmural invasion without secondary surgical intervention, and group C included four patients (36%) with reresection. The perioperation parameters and strategies were collected and compared. A review of the literature was performed simultaneously, and we concluded that unsuspected gallbladder cancer with nontransmural invasion needs no further treatment; however, aggressive reresection is beneficial to transmural invasion cancer, and prevention of bile spillage during LC should be the goal of every surgeon.
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Affiliation(s)
- Chien-Pin Chan
- Division of General Surgery, Department of Surgery, Chang-Hua Christian Hospital, Chang-Hua, Taiwan
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12
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Ding WH, Tsai PC. Determination of alkyltrimethylammonium chlorides in river water by gas chromatography/ion trap mass spectrometry with electron impact and chemical ionization. Anal Chem 2003; 75:1792-7. [PMID: 12713035 DOI: 10.1021/ac020536y] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This work describes a modified method to analyze alkyltrimethylammonium chlorides (ATMACs) in river water samples. The proposed method involves adding solid potassium iodide to water sample (pH adjusted to 10.0) as a counterion to enhance the extraction of ATMAC residues by dichloromethane liquid-liquid extraction. The iodide-ATMA+ ion pairs were demethylated to their corresponding nonionic alkyldimethylamines (ADMAs) by thermal decomposition in a GC injection port. The corresponding ADMAs were then identified and quantitated by gas chromatography/ion trap mass spectrometry (GC/MS) in electron impact and low-pressure positive ion chemical ionization (PICI) modes. A relatively high abundance of ADMAs was detected at a demethylation temperature above 300 degrees C in the injection port. Experimental results indicate that the proposed method is precise and sensitive in ATMACs analysis and allows quantitation at < or = 0.01 microg/L in 500 mL of the water samples. The enhanced selectivity of quasi-molecular ion chromatograms of C12-C18-ADMA, obtained using methanol PICI-MS, enables ATMAC residues to be identified at trace levels in environmental samples. Recovery of the ATMACs in various spiked water samples ranged from 70 to 94% while RSD ranged from 3 to 12%. The concentrations of total measured ATMAC residues in river water samples ranged from nondetectable to 1.24 microg/L.
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Affiliation(s)
- Wang-Hsien Ding
- Department of Chemistry, National Central University, Chung-Li, 32054, Taiwan.
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13
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Chan CP, Yang LH, Chang HC, Chen YL, Chen ST, Kuo SJ, Tsai PC. An easier technique for minimally invasive video-assisted thyroidectomy. Int Surg 2003; 88:109-13. [PMID: 12872906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
Because of the efforts of many pioneer surgeons, the minimally invasive video-assisted thyroidectomy (MIVAT) has been recognized as a safe procedure, offering advantages such as better cosmetic outcome and less analgesic need. The MIVAT technique was described in 51 selected patients in 2001. The technique was not therefore widely used because of the excess operating time compared with traditional thyroidectomy, and most importantly, this method needed a steep learning period. This study reports a modified MIVAT procedure, which can make this operation easier and shorten the time of learning. We compared the outcomes of the originally described methods with our modified method. The selection criteria for performing MIVAT were as follows: thyroid nodules in one lobe and less than 50 mm on their largest diameter, benign lesion proved by fine-needle biopsy, patient without history of thyroiditis, and no previous neck surgery or irradiation. All patients received lobectomy. Sixty patients were eligible for MIVAT during a period of 27 months. The patients were divided into two groups. Group A consisted of the 17 patients who underwent MIVAT using the original technique that was described previously. Group B consisted of the 43 patients who underwent MIVAT using a self-designed Army retractor with a mosaic ring. The mean operation time of Group A was 120 minutes and that of Group B was 59.2 minutes. The size of the incisions was no difference in either group. There were no postoperative complications except in one patient with transient recurrent laryngeal nerve palsy in Group A. There was one conversion to open thyroidectomy in Group A and none in Group B. The cosmetic results were no different between the two groups. In conclusion, the use of a modified Army retractor with a mosaic ring made the MIVAT procedure easier and offered similar advantages.
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Affiliation(s)
- Chien-Pin Chan
- Division of General Surgery, Department of Surgery, Chang-Hua Christian Hospital, Chang-Hua, Taiwan
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14
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Ko TP, Chen YK, Robinson H, Tsai PC, Gao YG, Chen AP, Wang AH, Liang PH. Mechanism of product chain length determination and the role of a flexible loop in Escherichia coli undecaprenyl-pyrophosphate synthase catalysis. J Biol Chem 2001; 276:47474-82. [PMID: 11581264 DOI: 10.1074/jbc.m106747200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli undecaprayl-pyrophosphate synthase (UPPs) structure has been solved using the single wavelength anomalous diffraction method. The putative substrate-binding site is located near the end of the betaA-strand with Asp-26 playing a critical catalytic role. In both subunits, an elongated hydrophobic tunnel is found, surrounded by four beta-strands (betaA-betaB-betaD-betaC) and two helices (alpha2 and alpha3) and lined at the bottom with large residues Ile-62, Leu-137, Val-105, and His-103. The product distributions formed by the use of the I62A, V105A, and H103A mutants are similar to those observed for wild-type UPPs. Catalysis by the L137A UPPs, on the other hand, results in predominantly the formation of the C(70) polymer rather than the C(55) polymer. Ala-69 and Ala-143 are located near the top of the tunnel. In contrast to the A143V reaction, the C(30) intermediate is formed to a greater extent and is longer lived in the process catalyzed by the A69L mutant. These findings suggest that the small side chain of Ala-69 is required for rapid elongation to the C(55) product, whereas the large hydrophobic side chain of Leu-137 is required to limit the elongation to the C(55) product. The roles of residues located on a flexible loop were investigated. The S71A, N74A, or R77A mutants displayed 25-200-fold decrease in k(cat) values. W75A showed an 8-fold increase of the FPP K(m) value, and 22-33-fold increases in the IPP K(m) values were observed for E81A and S71A. The loop may function to bridge the interaction of IPP with FPP, needed to initiate the condensation reaction and serve as a hinge to control the substrate binding and product release.
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Affiliation(s)
- T P Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
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15
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Chang SY, Tsai PC, Tseng CS, Liang PH. Refolding and characterization of a yeast dehydrodolichyl diphosphate synthase overexpressed in Escherichia coli. Protein Expr Purif 2001; 23:432-9. [PMID: 11722180 DOI: 10.1006/prep.2001.1511] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dehydrodolichyl diphosphate synthase (DDPPs) catalyzes the sequential condensation of isopentenyl diphosphate with farnesyl diphosphate to synthesize long-chain dehydrodolichyl diphosphate, which serves as a precursor of glycosyl carrier in glycoprotein biosynthesis in eukaryotes. To perform kinetic and structural studies of DDPPs, we have expressed yeast DDPPs using Escherichia coli as the host cell. Thioredoxin and His tag were utilized to increase the solubility of the recombinant protein and facilitate its purification using Ni-nitrilotriacetic acid (NTA) column. The protein was overexpressed in E. coli but mostly existed in pellet in the absence of detergent. The low quantity of soluble DDPPs was purified using Ni-NTA, Mono Q anion-exchange, and size-column chromatographies. The protein in the pellet was solubilized with 7 M urea and purified using Ni-NTA under denaturing condition. The protein refolding was achieved via the stepwise dialysis to remove the denaturant in the presence of 6 mM beta-mercaptoethanol. Detergent n-octyl-beta-d-glucopyranoside and Triton X-100 increased the solubility of the DDPPs so that refolding can be performed at higher protein concentration. Alternatively, on-column refolding was carried out in a single step to obtain the active protein in large quantities. beta-Mercaptoethanol and Triton were both required in this quick refolding process. The kinetic studies indicated that the soluble and refolded DDPPs have comparable activities (k(cat) = 2 x 10(-4) s(-1)). Unlike its bacterial homologue, undecaprenyl diphosphate synthase, yeast DDPPs activity was not enhanced by Triton.
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Affiliation(s)
- S Y Chang
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, 11529, Taiwan
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