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Chen Y, Choong LY, Lin Q, Philp R, Wong CH, Ang BK, Tan YL, Loh MCS, Hew CL, Shah N, Druker BJ, Chong PK, Lim YP. Differential expression of novel tyrosine kinase substrates during breast cancer development. Mol Cell Proteomics 2007; 6:2072-87. [PMID: 17855441 DOI: 10.1074/mcp.m700395-mcp200] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
To identify novel tyrosine kinase substrates that have never been implicated in cancer, we studied the phosphoproteomic changes in the MCF10AT model of breast cancer progression using a combination of phosphotyrosyl affinity enrichment, iTRAQ technology, and LC-MS/MS. Using complementary MALDI- and ESI-based mass spectrometry, 57 unique proteins comprising tyrosine kinases, phosphatases, and other signaling proteins were detected to undergo differential phosphorylation during disease progression. Seven of these proteins (SPAG9, Toll-interacting protein (TOLLIP), WBP2, NSFL1C, SLC4A7, CYFIP1, and RPS2) were validated to be novel tyrosine kinase substrates. SPAG9, TOLLIP, WBP2, and NSFL1C were further proven to be authentic targets of epidermal growth factor signaling and Iressa (gefitinib). A closer examination revealed that the expression of SLC4A7, a bicarbonate transporter, was down-regulated in 64% of the 25 matched normal and tumor clinical samples. The expression of TOLLIP in clinical breast cancers was heterogeneous with 25% showing higher expression in tumor compared with normal tissues and 35% showing the reverse trend. Preliminary studies on SPAG9, on the other hand, did not show differential expression between normal and diseased states. This is the first time SLC4A7 and TOLLIP have been discovered as novel tyrosine kinase substrates that are also associated with human cancer development. Future molecular and functional studies will provide novel insights into the roles of TOLLIP and SLC4A7 in the molecular etiology of breast cancer.
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Qua CS, Wong CH, Gopala K, Goh KL. Gastro-oesophageal reflux disease in chronic laryngitis: prevalence and response to acid-suppressive therapy. Aliment Pharmacol Ther 2007; 25:287-95. [PMID: 17269990 DOI: 10.1111/j.1365-2036.2006.03185.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Gastro-oesophageal reflux is thought to cause chronic laryngitis through laryngopharyngeal reflux. Response of laryngitis to treatment with acid-suppressive therapy supports this causal link. AIM To determine the prevalence of gastro-oesophageal reflux disease in patients with chronic laryngitis and response to proton-pump inhibitor therapy. METHODS Patients with chronic laryngitis were recruited. The frequency and severity of reflux and laryngeal symptoms were scored and laryngitis graded by laryngoscopy. All patients underwent esophagogastroduodenoscopy and 24-h ambulatory pH monitoring before receiving lansoprazole 30 mg b.d. for 8 weeks. RESULTS The prevalence of gastro-oesophageal reflux disease was 65.6% (21 of 32). Based on positive pH test, the prevalence was 25% (eight of 32). The change in laryngeal symptom score and laryngitis grade was significantly higher in GERD compared with non-GERD patients (P = 0.010 for both). The proportion of patients with marked/moderate improvement in laryngeal symptoms were significantly higher in patients with reflux (14 of 21, 67%) compared to those without reflux (two of 11, 18%; P = 0.026). CONCLUSIONS The prevalence of gastro-oesophageal reflux disease amongst our patients with chronic laryngitis was high. The response to treatment with proton-pump inhibitors in patients with reflux disease compared to those without underlined the critical role of acid reflux in a subset of patients with chronic laryngitis.
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Chiu KP, Wong CH, Chen Q, Ariyaratne P, Ooi HS, Wei CL, Sung WKK, Ruan Y. PET-Tool: a software suite for comprehensive processing and managing of Paired-End diTag (PET) sequence data. BMC Bioinformatics 2006; 7:390. [PMID: 16934139 PMCID: PMC1564156 DOI: 10.1186/1471-2105-7-390] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 08/25/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND We recently developed the Paired End diTag (PET) strategy for efficient characterization of mammalian transcriptomes and genomes. The paired end nature of short PET sequences derived from long DNA fragments raised a new set of bioinformatics challenges, including how to extract PETs from raw sequence reads, and correctly yet efficiently map PETs to reference genome sequences. To accommodate and streamline data analysis of the large volume PET sequences generated from each PET experiment, an automated PET data process pipeline is desirable. RESULTS We designed an integrated computation program package, PET-Tool, to automatically process PET sequences and map them to the genome sequences. The Tool was implemented as a web-based application composed of four modules: the Extractor module for PET extraction; the Examiner module for analytic evaluation of PET sequence quality; the Mapper module for locating PET sequences in the genome sequences; and the Project Manager module for data organization. The performance of PET-Tool was evaluated through the analyses of 2.7 million PET sequences. It was demonstrated that PET-Tool is accurate and efficient in extracting PET sequences and removing artifacts from large volume dataset. Using optimized mapping criteria, over 70% of quality PET sequences were mapped specifically to the genome sequences. With a 2.4 GHz LINUX machine, it takes approximately six hours to process one million PETs from extraction to mapping. CONCLUSION The speed, accuracy, and comprehensiveness have proved that PET-Tool is an important and useful component in PET experiments, and can be extended to accommodate other related analyses of paired-end sequences. The Tool also provides user-friendly functions for data quality check and system for multi-layer data management.
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Wong CH, Chua CJ, Liam CK, Goh KL. Gastro-oesophageal reflux disease in 'difficult-to-control' asthma: prevalence and response to treatment with acid suppressive therapy. Aliment Pharmacol Ther 2006; 23:1321-7. [PMID: 16629937 DOI: 10.1111/j.1365-2036.2006.02888.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
BACKGROUND The causal association between gastro-oesophageal reflux disease (GERD) and difficult-to-control asthma is unclear. AIM To determine the prevalence of GERD and response to proton pump inhibitor therapy in patients with difficult-to-control asthma. METHODS Consecutive patients with difficult-to-control asthma as defined by persistent and recurrent symptoms despite on optimal asthmatic medications were recruited for the study. GERD was diagnosed by symptoms, gastroscopy and 24-h oesophageal pH monitoring. All patients were prescribed a course of lansoprazole 30 mg daily for 8 weeks. Improvement to treatment was assessed by a change in pulmonary symptom score and also by patient's subjective assessment of improvement. RESULTS Seventeen of 30 (56.7%) patients with difficult-to-control asthma were diagnosed with GERD. Pulmonary symptom score improved significantly only in patients with GERD (35.0 to 21.0; P = 0.002). Twelve of 16 (75%) patients with GERD reported an improvement in asthma symptoms; 1 of 11 (9.1%) without GERD reported mild symptom improvement. There was no significant change in peak expiratory flow rate and forced expiratory volume. CONCLUSIONS More than half of patients with difficult-to-control asthma were diagnosed with GERD. In these patients the severity of asthma improved significantly with potent acid suppression therapy. This underlines the critical role of acid reflux in this subset of patients with difficult-to-control asthma.
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Li SSL, So YC, Wong CH, Yiu SF, Chan KT. Treatment of long, diffuse in-stent restenosis with sirolimus-eluting stents. THE JOURNAL OF INVASIVE CARDIOLOGY 2004; 16:81-3. [PMID: 14760198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Treatment of long, diffuse in-stent restenosis remains a therapeutic challenge. We report the successful use of multiple sirolimus-eluting stents (three 33-mm long stents) in a long, diffuse in-stent restenotic lesion. No major adverse cardiovascular events, including acute/subacute/delayed stent thrombosis, were noted at ten months. Angiography at six months showed widely patent stents with 19% restenosis only at the worst segment.
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Li SSL, Lam CW, So YC, Wong CH, Yiu SF, Ho D, Chan KW, Chan KT. The use of a distal occlusion balloon protection device in acute coronary syndrome. Int J Cardiol 2003; 92:281-4. [PMID: 14659866 DOI: 10.1016/s0167-5273(03)00097-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We report our early experience in using the PercuSurge GuardWire Plus system as a distal protection device in patients with acute coronary syndrome and acute myocardial infarction. Forty-three patients received percutaneous coronary intervention with the GuardWire Plus system. Thirteen had unstable angina, five had non-Q myocardial infarction and 25 had ST segment elevation myocardial infarction. Forty-one target lesions were in native coronary vessels and two were in saphenous vein grafts. Total occlusion occurred in 18 patients. The mean occlusion time by the distal protective balloon was 262.8 +/- 114.1 s. Preoperatively, TIMI 0 flow was present in 18, TIMI II flow in two and TIMI III flow in 23 patients. Post-operatively, TIMI II and TIMI III flow were established in two and 41 patients, respectively. All procedures were successful and the GuardWire Plus system was successfully deployed in all but two patients. There was no procedure-related major adverse clinical event. There was no major adverse clinical event at 30 days. There was no device-related complication. We believe that the GuardWire Plus system is safe and feasible in patients with acute coronary syndrome and acute myocardial infarction.
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Wong CH, Wong SF, Shen L. Correlates of habitual walking and sports/leisure-time physical activity in older persons in Singapore: interaction effects between educational attainment and gender. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2003; 32:801-6. [PMID: 14716950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
INTRODUCTION We examined for demographic and psychosocial correlates on the participation of habitual walking and sports/leisure-time physical activity (LTPA) among older persons in Singapore. MATERIALS AND METHODS In an observational study, 177 Chinese, community/urban-dwelling, ambulant, non-disabled participants > or = 50 years old were recruited from a health promotion programme. The main outcome measures were self-reported participation in habitual walking and sports/LTPA. Variables examined include highest educational attainment, demographic and health characteristics, social contact and health knowledge. Interaction between gender and educational attainment was also examined. RESULTS The mean age of participants was 62.5 +/- 7.8 years. The effects of educational level were significant on habitual walking (P = 0.02), while that of age, self-rated health and interaction between gender and educational level were significant for sports/LTPA (P = 0.012, P = 0.002 and P = 0.019, respectively). Men with higher education had a higher self-reported sport/LTPA, while in women; those with lower education attainment had a higher participation. CONCLUSION Unlike findings from Western developed nations, previous studies done in Japan and Singapore found that educational level and health behaviours may not be positively associated. In this study, there is a negative correlation between educational attainment and participation in habitual walking and sports/LTPA, especially among older Singaporean women.
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Abstract
Deliberate self-injection of metallic mercury into subcutaneous tissue is uncommon. A 41-year-old lady with a history of schizophrenia was admitted to our hospital after deliberate injection of metallic mercury into her right wrist and antecubital fossa. Physical examination was unremarkable except for the injection marks over right antecubital fossa and wrist. The presence of subcutaneous mercury deposits in her right elbow and wrist was confirmed by X-rays and ultrasound scan. Three days later, erythema, swelling, induration and tenderness were seen over the injection sites. At the operation on day 9, mercury streaks were seen within the brachialis muscle belly, surrounded by friable necrotic tissues along the tract. A similar picture was noted in her right wrist. The necrotic tissues and mercury streaks were removed. The patient had been unco-operative and she only received incomplete treatment with dimercaprol and 2,3-dimercaptosuccinic acid. Her total blood mercury level (normal < 50 nmol/L) decreased from 101-151 nmol/L in the first two weeks to 42 nmol/L 3 months later. Her 24-hour urinary mercury excretion (normal < 10 nmol) changed from 55.7-209.5 nmol in the first 7 weeks to 125.4 nmol 3 months later. This case illustrates that soft tissue metallic mercury can produce local necrosis and may allow continuous absorption with persistent elevations in blood and urinary mercury levels. Therefore, early surgical removal of subcutaneous mercury deposits is required to prevent local complications and minimize the risk of systemic absorption and toxicity.
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Li SSL, Wong CH, Lam CWLW. Renal angioplasty under protection of the PercuSurge GuardWire Plus System. THE JOURNAL OF INVASIVE CARDIOLOGY 2003; 15:148-50. [PMID: 12612389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Renal artery revascularization with angioplasty may preserve renal function and facilitate hypertension control. However, in a significant proportion of patients, renal function may deteriorate after the procedure. Distal microembolization has been implicated as a possible cause; it may be prevented with distal protection during the procedure. We report a case of successful renal angioplasty and stenting using the PercuSurge GuardWire Plus system.
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Chen WS, Wong CH, Cillekens L. Dengue antibodies in a suburban community in Malaysia. THE MEDICAL JOURNAL OF MALAYSIA 2003; 58:142-3. [PMID: 14556343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
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Bonser RS, Wong CH, Harrington D, Pagano D, Wilkes M, Clutton-Brock T, Faroqui M. Failure of retrograde cerebral perfusion to attenuate metabolic changes associated with hypothermic circulatory arrest. J Thorac Cardiovasc Surg 2002; 123:943-50. [PMID: 12019380 DOI: 10.1067/mtc.2002.120333] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVES Although retrograde cerebral perfusion has become a popular adjunctive technique and may improve cerebral ischemic tolerance during hypothermic circulatory arrest, direct cerebral metabolic benefit has yet to be demonstrated in human subjects. We investigated the post-arrest metabolic phenomena with and without retrograde cerebral perfusion in patients. METHODS In a prospective randomized trial, 42 patients undergoing aortic surgery requiring hypothermic circulatory arrest were allocated to receive hypothermic circulatory arrest alone (n = 21) or hypothermic circulatory arrest with additional retrograde cerebral perfusion (n = 21). Circulatory arrest was commenced at 15 degrees C, and retrograde perfusion was instituted through the superior vena cava at a maximum jugular bulb pressure of 25 mm Hg. Transcranial, paired, repeated samples of the arterial and jugular bulb blood were analyzed for oxygen and glucose. Velocity in the right middle cerebral artery was also measured simultaneously. RESULTS There were 3 (7.1%) deaths and 3 (7.1%) episodes of neurologic deficit. Mean bypass and circulatory arrest duration (in minutes) were similar between groups (P =.4 and.14). The mean retrograde perfusion duration was 23 minutes. Post-arrest nasopharyngeal temperature was similar (15.3 degrees C vs. 15.3 degrees C). Retrograde perfusion did not affect post-arrest oxygen extraction, glucose extraction, or jugular bulb Po(2). There was no immediate lactate release immediately after hypothermic circulatory arrest. CONCLUSIONS Retrograde cerebral perfusion did not influence immediate post-arrest nasopharyngeal temperature or cerebral metabolic recovery. The low jugular bulb Po(2) suggests equivalent ischemia. These findings cast doubt on the effectiveness of retrograde cerebral perfusion as a metabolic adjunct to hypothermic circulatory arrest.
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Wong CH, Watson DAR, Wilson JD, Chew GYJ, Chong GC. Acute thyroiditis caused by Streptococcus agalactiae. Intern Med J 2002; 32:195-6. [PMID: 11951937 DOI: 10.1046/j.1444-0903.2001.00185.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Huang EYK, Li JY, Wong CH, Tan PPC, Chen JC. Dansyl-PQRamide, a possible neuropeptide FF receptor antagonist, induces conditioned place preference. Peptides 2002; 23:489-96. [PMID: 11835998 DOI: 10.1016/s0196-9781(01)00632-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Neuropeptide FF (NPFF) is an endogenous anti-opioid peptide. NPFF could potentiate the naloxone-precipitated morphine withdrawal syndromes in morphine-dependent rats, indicating the possible involvement of the endogenous NPFF system in opioid analgesia and dependence. The present study was performed to examine the effects of dansyl-PQRamide (dns-PQRa), a putative NPFF antagonist, on conditioned place preference (CPP), in addition, its interaction with the opioid system. Two CPP experiments were conducted. First, rats were treated with dns-PQRa (4-13 mg/kg, i.p.) and paired with the non-preferred compartment while the vehicle was paired with the preferred compartment. Second, similar to experiment 1 except naloxone (1 mg/kg, i.p.) was given 10 min prior to each dns-PQRa administration. The post-drug place preference was examined after 4 alternative pairings. Another group of animals after repetitive dns-PQRa treatments were analyzed for levels of neurotransmitters in discrete brain areas. Dns-PQRa (4-13 mg/kg, i.p.) induced a significant dose-dependent CPP. The dns-PQRa-induced CPP was completely blocked by pretreatment with 1 mg/kg i.p. naloxone, while naloxone alone did not induce any place aversion. The chronic dns-PQRa-treated (13 mg/kg, i.p., b.i.d.) rats caused a significant increase in 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid in the olfactory tubercle compared to the vehicle-treated controls. There was also an increase in the turnover of serotonin in the olfactory tubercle, nucleus accumbens and medial prefrontal cortex. These results suggest that blockade of the NPFF system produces rewarding, possibly via an inhibition of the anti-opioid action of NPFF. These results also reveal a close relationship between NPFF, drug rewarding and the dopaminergic and serotoninergic neurons in the mesolimbic system.
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Sears P, Tolbert T, Wong CH. Enzymatic approaches to glycoprotein synthesis. GENETIC ENGINEERING 2002; 23:45-68. [PMID: 11570106 DOI: 10.1007/0-306-47572-3_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Wong CH, Watson B, Smith J, Hamilton JR, Hasan A. The use of left heart bypass in adult and recurrent coarctation repair. Eur J Cardiothorac Surg 2001; 20:1199-201. [PMID: 11717028 DOI: 10.1016/s1010-7940(01)00987-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES Paraplegia following coarctation repair occurs in 0.4% of infants. However, for older children, adults and re-operations, the incidence can be as high as 2.6%. Yet there is no consensus on the need for spinal cord protection or the optimal method. This paper reports our experience with left heart bypass (LHB) in adult and re-do coarctation. METHODS Between 1997 and 2000, nine patients underwent elective resection of coarctation (three re-dos, two balloons) with a mean age of 17.9 years (range, 8-44) and weight of 52 kg (range, 17.3-109). The mean trans-coarctation gradient was 29.6 mmHg (range, 20-45). Patients were placed on LHB using a centrifugal pump with full heparinization through a fourth-space thoracotomy. Patients were cooled to 31-34 degrees C for additional spinal cord protection. Repair was carried out with an inter-positional graft (5/9), a Gore-Tex patch (2/9) or end-to-end anastomosis (2/9). The mean cross-clamp and bypass times were 36.4 (range, 19-65) and 40.3 min (range, 22-70), respectively. RESULTS No patient developed transient or permanent paraplegia. The mean peak creatinine was 80 micromol/l (range, 51-123). CONCLUSIONS LHB is simple, easy and safe to implement, and is the only technique capable of maintaining independent upper and lower body perfusion pressure. Potentially, it provides the best spinal cord protection, and extends the margin of safety and time to execute an accurate repair.
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Izumi M, Shen GJ, Wacowich-Sgarbi S, Nakatani T, Plettenburg O, Wong CH. Microbial glycosyltransferases for carbohydrate synthesis: alpha-2,3-sialyltransferase from Neisseria gonorrheae. J Am Chem Soc 2001; 123:10909-18. [PMID: 11686694 DOI: 10.1021/ja011382r] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The alpha-2,3-sialyltransferase from Neisseria gonorrheae was overproduced in E. coli for exploitation of its substrate specificity and synthetic utility. Several potential acceptor substrates were synthesized in this study, including mono- and oligosaccharides, glycolipids, and glycopeptides and their sulfate derivatives. Some CMP-sialic acid derivatives with modification at the C-5 position were also prepared for evaluation as donor substrates. It was found that the enzyme exhibits a broader acceptor substrate specificity when compared to other sialyltransferases, though the donor specificity is quite limited. Application of the enzyme to the preparative synthesis of representative sialyl glycoconjugates has been demonstrated. On the basis of this work and the work of others, this enzyme is the most versatile and synthetically useful among all sialyltransferases known to date, especially for the synthesis of sulfate-containing glycoconjugates.
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Saotome C, Wong CH, Kanie O. Combinatorial library of five-membered iminocyclitol and the inhibitory activities against glyco-enzymes. CHEMISTRY & BIOLOGY 2001; 8:1061-70. [PMID: 11731297 DOI: 10.1016/s1074-5521(01)00074-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND Oligosaccharide processing enzymes are important classes of catalysts involved in synthesizing specific oligosaccharide structures on proteins and sphingolipids. Development of specific inhibitors of such enzymes is of current interest as these inhibitors may be used to control cellular functions. Five-membered iminocyclitols have been shown to be potent inhibitors of such enzymes. Since a rational design and synthesis of inhibitors is often extremely difficult due to the limited information regarding the structure of the active site, we carried out a combinatorial library approach. RESULTS To create diversity, we decided to use an aldehyde group of a protected iminocyclitol for reductive amination and the Strecker reaction. After transformation of the nitrile group introduced by the Strecker reaction into an amine and amide and complete deprotection, a small library of five-membered iminocyclitols consisting of 27 compounds was synthesized. A series of compounds obtained by reductive amination was first screened as potential inhibitors of glycosidases and glycosyltransferases. Among them, compounds carrying a C(10)-alkyl group showed marked enhancement of inhibitory activity against alpha-mannosidase at 10 microM concentration when compared with its parent compound and deoxymannojirimycin. Furthermore, compounds having the phenylethyl group showed an extremely strong inhibitory effect against alpha-galactosaminidase at a K(i) value of 29.4 nM. Compounds with an aminomethyl and amide group at the C-1' position of these two molecules showed a decrease in inhibitory activities. CONCLUSIONS A combinatorial approach based on five-membered iminocyclitols with a galacto-configuration was exploited. The potential usefulness of the library as a source of inhibitors of glycoenzymes is clearly shown in this study.
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Heine A, DeSantis G, Luz JG, Mitchell M, Wong CH, Wilson IA. Observation of covalent intermediates in an enzyme mechanism at atomic resolution. Science 2001; 294:369-74. [PMID: 11598300 DOI: 10.1126/science.1063601] [Citation(s) in RCA: 237] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In classical enzymology, intermediates and transition states in a catalytic mechanism are usually inferred from a series of biochemical experiments. Here, we derive an enzyme mechanism from true atomic-resolution x-ray structures of reaction intermediates. Two ultra-high resolution structures of wild-type and mutant d-2-deoxyribose-5-phosphate (DRP) aldolase complexes with DRP at 1.05 and 1.10 angstroms unambiguously identify the postulated covalent carbinolamine and Schiff base intermediates in the aldolase mechanism. In combination with site-directed mutagenesis and (1)H nuclear magnetic resonance, we can now propose how the heretofore elusive C-2 proton abstraction step and the overall stereochemical course are accomplished. A proton relay system appears to activate a conserved active-site water that functions as the critical mediator for proton transfer.
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Liu H, Sadamoto R, Sears PS, Wong CH. An efficient chemoenzymatic strategy for the synthesis of wild-type and vancomycin-resistant bacterial cell-wall precursors: UDP-N-acetylmuramyl-peptides. J Am Chem Soc 2001; 123:9916-7. [PMID: 11583564 DOI: 10.1021/ja011708w] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Le VD, Mak CC, Lin YC, Elder JH, Wong CH. Structure-activity studies of FIV and HIV protease inhibitors containing allophenylnorstatine. Bioorg Med Chem 2001; 9:1185-95. [PMID: 11377177 DOI: 10.1016/s0968-0896(00)00346-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interaction of P1 and P3 side chains with the combining S1 and S3 hydrophobic subsites of HIV and FIV proteases has been explored using asymmetric competitive inhibitors. The inhibitors evaluated contained (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid (allophenylnorstatine) as the hydroxymethylcarbonyl isostere, (R)-5,5-dimethyl-1, 3-thiazolidine-4-carbonyl as P1', Val as P2 and P2' residues, and a variety of amino acids at the P3 and P3' positions. All inhibitors showed competitive inhibition of both enzymes with higher potency against the HIV protease in vitro. Within this series, 31 (VLE776) is the most effective inhibitor against FIV protease, and it contains Phe at P3, but no P3' residue. VLE776 also exhibited potent antiviral activities against the drug-resistant HIV mutants (G48V and V82F) and the TL3-resistant HIV mutants. Explanation of the inhibition activities was described. In addition, a new strategy was described for development of bifunctional inhibitors, which combine the protease inhibitor and another enzyme inhibitor in one molecule.
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Bühler B, Lin YC, Morris G, Olson AJ, Wong CH, Richman DD, Elder JH, Torbett BE. Viral evolution in response to the broad-based retroviral protease inhibitor TL-3. J Virol 2001; 75:9502-8. [PMID: 11533212 PMCID: PMC114517 DOI: 10.1128/jvi.75.19.9502-9508.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
TL-3 is a protease inhibitor developed using the feline immunodeficiency virus protease as a model. It has been shown to efficiently inhibit replication of human, simian, and feline immunodeficiency viruses and therefore has broad-based activity. We now demonstrate that TL-3 efficiently inhibits the replication of 6 of 12 isolates with confirmed resistance mutations to known protease inhibitors. To dissect the spectrum of molecular changes in protease and viral properties associated with resistance to TL-3, a panel of chronological in vitro escape variants was generated. We have virologically and biochemically characterized mutants with one (V82A), three (M46I/F53L/V82A), or six (L24I/M46I/F53L/L63P/V77I/V82A) changes in the protease and structurally modeled the protease mutant containing six changes. Virus containing six changes was found to be 17-fold more resistant to TL-3 in cell culture than was wild-type virus but maintained similar in vitro replication kinetics compared to the wild-type virus. Analyses of enzyme activity of protease variants with one, three, and six changes indicated that these enzymes, compared to wild-type protease, retained 40, 47, and 61% activity, respectively. These results suggest that deficient protease enzymatic activity is sufficient for function, and the observed protease restoration might imply a selective advantage, at least in vitro, for increased protease activity.
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Kozlov IA, Mao S, Xu Y, Huang X, Lee L, Sears PS, Gao C, Coyle AR, Janda KD, Wong CH. Synthesis of solid-supported mirror-image sugars: a novel method for selecting receptors for cellular-surface carbohydrates. Chembiochem 2001; 2:741-6. [PMID: 11948856 DOI: 10.1002/1439-7633(20011001)2:10<741::aid-cbic741>3.0.co;2-b] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We introduced a novel method, through mirror-image phage display, for the identification of high-affinity D-peptides to target specific cell-surface carbohydrates. Both 3-deoxy-alpha-L-manno-2-octulosonic acid (L-KDO) and L-sialic acid and an L-sialo-disaccharide have been synthesized and attached to a solid support for selection of high-affinity peptide binders displayed on phages. Our initial studies in this effort produce single-chain Fab sequences and dodecapeptides that bind to sialic acid and KDO with nanomolar and high micromolar affinity.
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Liu J, Shikhman AR, Lotz MK, Wong CH. Hexosaminidase inhibitors as new drug candidates for the therapy of osteoarthritis. CHEMISTRY & BIOLOGY 2001; 8:701-11. [PMID: 11451670 DOI: 10.1016/s1074-5521(01)00045-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Articular cartilage from patients with osteoarthritis is characterized by a decreased concentration and reduced size of glycosaminoglycans. Degeneration of the cartilage matrix is a multifactorial process, which is due in part to accelerated glycosaminoglycan catabolism. Recently, we have demonstrated that hexosaminidase represents the dominant glycosaminoglycan-degrading glycosidase released by chondrocytes into the extracellular compartment and is the dominant glycosidase in synovial fluid from patients with osteoarthritis. Inhibition of hexosaminidase activity may represent a novel approach to the prevention of cartilage matrix glycosaminoglycan degradation and a potentially new strategy to treat osteoarthritis. RESULTS We have synthesized and investigated a series of iminocyclitols designed as transition-state analog inhibitors of human hexosaminidase, and demonstrated that the five-membered iminocyclitol 4 expresses the strongest inhibitory activity with K(i)=24 nM. Inhibition of hexosaminidase activity in human cultured articular chondrocytes and human chondrosarcoma cells with iminocyclitol 4 resulted in accumulation of hyaluronic acid and sulfated glycosaminoglycans in the cell-associated fraction. Similarly, incubation of human cartilage tissue with iminocyclitol 4 resulted in an accumulation of glycosaminoglycans in the pericellular compartment. CONCLUSIONS Inhibition of hexosaminidase activity represents a new strategy for preventing or even reversing cartilage degradation in patients with osteoarthritis.
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Wong CH, Chow L, Yen CH, Ho PC, Yip R, Hung LK. Uncommon hand tumours. HAND SURGERY : AN INTERNATIONAL JOURNAL DEVOTED TO HAND AND UPPER LIMB SURGERY AND RELATED RESEARCH : JOURNAL OF THE ASIA-PACIFIC FEDERATION OF SOCIETIES FOR SURGERY OF THE HAND 2001; 6:67-80. [PMID: 11677668 DOI: 10.1142/s0218810401000564] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This paper presented clinical examples of some rare or uncommon presentations of tumours of the hand, including glomus tumour, intraosseous dermoid, fibrolipoma of the radial nerve, blastomycotic cyst and synovial sarcoma. Each lesion is illustrated by review of case histories, radiological and pathological features.
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Miller BJ, Geraghty TJ, Wong CH, Hall DF, Cohen JR. Outcome of the acute abdomen in patients with previous spinal cord injury. ANZ J Surg 2001; 71:407-11. [PMID: 11450915 DOI: 10.1046/j.1440-1622.2001.02146.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Patients with spinal cord injury (SCI) have always posed difficulties for the diagnosis of an acute abdomen. The aim of the present study was to define this problem retrospectively at Princess Alexandra Hospital and to assess the results of treatment for these patients. METHODS A retrospective review was conducted of 133 SCI patients admitted with an acute abdomen in the 16 years prior to this analysis at the Spinal Injuries Unit (SIU) of Princess Alexandra Hospital. There were 21 patients who conformed to the study criteria. All the patients had sustained traumatic SCI at or above the level of T11, more than 1 month prior to admission. RESULTS There were 13 male and eight female patients. The time lapse between SCI and the onset of an acute abdomen ranged from 1.5 months to 27 years. The age range was 26-79 years. The majority of patients had C6 injuries (six patients). There were 18 patients with injury levels above T6 and three patients with injuries below this level. The time taken to diagnose the cause of the acute abdomen ranged between I day and 3 months. Investigations were found to be useful in making the diagnoses in 61.9% of cases. There were 14 patients who had surgical interventions. Five patients had surgical complications and there were two deaths in the study. The length of follow up was 1-132 months. The mortality in the study was 9.5%. CONCLUSION An aggressive approach to the diagnosis and treatment of the acute abdomen in SCI patients with suspicious symptoms is recommended. A high index of suspicion should be maintained in those patients with pre-existing SCI who present with abdominal trauma.
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