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Hartley LM, Ng SY, Dale RC, Church AJ, Martinez A, de Sousa C. Immune mediated chorea encephalopathy syndrome in childhood. Dev Med Child Neurol 2002; 44:273-7. [PMID: 11995896 DOI: 10.1017/s0012162201002055] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We report four previously healthy female children, aged between 3 and 8 years, who presented with encephalopathy and an extrapyramidal movement disorder (chorea n=4, rigidity n=2, oculogyric crisis n=2). In addition, an acute behavioural disturbance occurred in two patients and mutism in two others. Seizures heralded the onset of the illness in three patients. Acute MRI was either normal or initially normal with later generalized cerebral atrophy. All infective (including streptococcus), biochemical, and metabolic investigations were normal, although all four patients had oligoclonal bands in the (CSF) but not the serum, indicating intrathecal immunoglobulin synthesis. All four children made an apparently full recovery within four months of the onset. We suggest that these patients represent an immune-mediated movement disorder and encephalopathy syndrome.
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Sharma PK, Songra AK, Ng SY. Intraoperative ultrasound-guided retrieval of an airgun pellet from the tongue: a case report. Br J Oral Maxillofac Surg 2002; 40:153-5. [PMID: 12180211 DOI: 10.1054/bjom.2001.0733] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Real-time intraoperative ultrasonography was used to detect and facilitate removal of an airgun pellet from the tongue of a 14-year-old boy. Diagnostic ultrasound was crucial in clarifying the positional relation between the foreign body and the instrument used, enabling safe, precise and rapid retrieval during a potentially hazardous surgical operation.
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Ng SY, Songra A, Ali N, Carter JL. Ultrasound features of osteosarcoma of the mandible--a first report. ORAL SURGERY, ORAL MEDICINE, ORAL PATHOLOGY, ORAL RADIOLOGY, AND ENDODONTICS 2001; 92:582-6. [PMID: 11709698 DOI: 10.1067/moe.2001.116821] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ultrasound imaging is becoming widely used in the head and neck region as a first-line investigation to assess soft tissue swellings. Clinicians should be aware of the potential of diagnostic ultrasound to identify important signs of malignant disease involving bone. Involvement of the mandible by osteosarcoma is uncommon. A young adult patient presented with facial swelling and an apparently infected lower third molar extraction socket. Subtle signs were missed on dental radiographs. Diagnostic ultrasound investigation was pivotal in identifying sinister signs: namely, soft tissue mass associated with bone thinning, erosion, expansion, and the "sunray" appearance of the buccal cortex, which were suggestive of osteosarcoma. These findings enabled priority to be given to subsequent investigations using other modalities. We present a first report of the ultrasound features of osteosarcoma of the mandible and consider this to be a useful modality in an initial investigation.
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Hardee PS, Carter JL, Piper KM, Ng SY. Metachronous bilateral primary adenocarcinoma of the submandibular glands. ORAL SURGERY, ORAL MEDICINE, ORAL PATHOLOGY, ORAL RADIOLOGY, AND ENDODONTICS 2001; 91:455-61. [PMID: 11312463 DOI: 10.1067/moe.2001.113547] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A young woman developed an unusual adenocarcinoma in each submandibular salivary gland at an interval of 30 months. This presentation has not been described previously. The possible etiology for this and treatment options are discussed. The choice of diagnostic imaging (ultrasound versus magnetic resonance imaging) is highlighted. As a result of regular follow-ups using diagnostic ultrasound, a second tumor was observed to reach a dimension of 8 mm in less than 6 months. This is probably the first report documenting the extent of initial growth of this rare tumor.
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Rothen-Weinhold A, Schwach-Abdellaoui K, Barr J, Ng SY, Shen HR, Gurny R, Heller J. Release of BSA from poly(ortho ester) extruded thin strands. J Control Release 2001; 71:31-7. [PMID: 11245906 DOI: 10.1016/s0168-3659(00)00348-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A solventless procedure was used where powdered polymer and micronized protein were intimately mixed and then extruded into 1 mm strands that were cut to the desired length. The polymers used were poly(ortho esters) specifically designed to allow extrusion in the neighborhood of 70 degrees C. At these temperatures many proteins maintain activity in the dry state. In vitro erosion and BSA release results indicate that after a fairly long lag-time, BSA release and polymer erosion occur concomitantly indicating an erosion-controlled process. The lag-time could be eliminated by the addition to the mixture prior to extrusion between 1 and 5 wt% poly(ethylene glycol) or its methoxy derivatives. The lag-time could also be eliminated by using an AB-block copolymer where A is poly(ortho ester) and B is poly(ethylene glycol).
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Ng SY, Pinto P. Ultrasound-guided retrieval of labial minor salivary gland sialoliths. Dentomaxillofac Radiol 2000; 29:319-22. [PMID: 10980569 DOI: 10.1038/sj/dmfr/4600545] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We report a case of minor salivary gland sialolithiasis presenting as acute, painful swelling of the upper lip. Conventional, unguided, incision and drainage removed three of the sialoliths. Diagnostic ultrasound identified two further sialoliths which were successfully removed with real-time, ultrasound-guided, needle localization. This technique of sialolith retrieval has not been previously reported.
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Heller J, Barr J, Ng SY, Shen HR, Schwach-Abdellaoui K, Einmahl S, Rothen-Weinhold A, Gurny R, Emmahl S. Poly(ortho esters) - their development and some recent applications. Eur J Pharm Biopharm 2000; 50:121-8. [PMID: 10840196 DOI: 10.1016/s0939-6411(00)00085-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Poly(ortho esters) have been under development since the early 1970s and four families of such polymers have been described. Of most interest are poly(ortho ester) III and poly(ortho ester) IV. Poly(ortho ester) III is a semisolid material that has been shown to be highly biocompatible and is currently being investigated as an adjunct to glaucoma filtering surgery and other ocular applications. However, the polymerization is difficult to control and is not readily scaled up. Poly(ortho ester) IV can be easily prepared in a highly reproducible manner, is very stable provided moisture is rigorously excluded and has also been shown to be highly biocompatible. It is currently under development for a variety of applications, such as ocular delivery, protein release, post-operative pain treatment and post-operative cancer treatment.
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Hasnaini M, Ng SY. Extensive temporal bone pneumatization: incidental finding in a patient with TMJ dysfunction. DENTAL UPDATE 2000; 27:187-9. [PMID: 11218454 DOI: 10.12968/denu.2000.27.4.187] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
An 18-year-old male presented with symptoms of temporomandibular joint dysfunction. A panoramic radiograph revealed slight erosion of the condylar heads, and an incidental finding of multilocular radiolucencies in the zygomatic processes of the right and left temporal bones. CT scans were undertaken to exclude any sinister cause. The radiolucencies were shown to be extensive bilateral pneumatization of the temporal bones. Conservative management relieved the symptoms of TMJ dysfunction.
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Ng SY, Shen HR, Lopez E, Zherebin Y, Barr J, Schacht E, Heller J. Development of a poly(ortho ester) prototype with a latent acid in the polymer backbone for 5-fluorouracil delivery. J Control Release 2000; 65:367-74. [PMID: 10699295 DOI: 10.1016/s0168-3659(99)00218-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A study has been carried out to determine whether the latest family of poly(ortho esters) can be converted into a practical delivery system. This polymer differs from the previously described polymers in that it incorporates a short segment of a latent acid in the polymer backbone. The following issues were specifically addressed: (a) can the erosion and drug release be reproducibly controlled to yield the desired drug release kinetics and erosion rates? (b) Is the polymer stable during radiation sterilization, on storage and on fabrication? (c) Can the polymer be prepared reproducibly at the desired molecular weights and molecular weight distribution? (d) Is the polymer safe for its intended application and does the in vivo erosion proceed to completion? (e) Can the polymer be easily fabricated into desired configurations? Studies have shown that if the synthesis is carefully controlled, the desired molecular weights can be reproducibly prepared, that the polymer is reasonably stable after irradiation at 24 kGy and during storage at room temperature under anhydrous conditions, and that it can be safely thermally fabricated at temperatures in the neighborhood of 120 degrees C. When polymer devices were implanted intraperitoneally in rats the polymer eroded to completion without any overt toxicity as determined by the measured parameters.
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Ng SY. Hair calcium and magnesium levels in patients with fibromyalgia: a case center study. J Manipulative Physiol Ther 1999; 22:586-93. [PMID: 10626702 DOI: 10.1016/s0161-4754(99)70019-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Fibromyalgia is not an uncommon condition. Because its cause has yet to be identified. treatment of the condition has been empirical; frequently, outcomes are unsatisfactory. Some patients with fibromyalgia were observed to have high hair calcium and magnesium levels compared with healthy subjects. Because of this and because supplementing calcium with magnesium to fibromyalgia subjects reduced the number of tender points detected by digital palpation, it is worth investigating if patients with fibromyalgia have significantly higher hair calcium and magnesium levels than their healthy counterparts. OBJECTIVES To determine the degree of difference between the hair calcium and magnesium levels in patients with fibromyalgia and in healthy subjects. METHODS The study was retrospective and of paired design. Twelve patients who had hair analysis performed and met the criteria of fibromyalgia defined by American College of Rheumatology (1990) were selected consecutively from clinical files. These patients were then matched by age and sex to 12 healthy subjects selected consecutively from the same patient files who had hair analysis performed for checkup purposes. Nonparametric Wilcoxon rank sum tests were used to determine if the hair calcium and magnesium levels in patients with fibromyalgia were significantly higher than that of the control subjects. RESULTS Wilcoxon rank sum tests showed that patients with fibromyalgia had significantly higher calcium and magnesium levels than the control subjects at alpha = .025 and .05, respectively. CONCLUSION In the presence of high hair calcium and magnesium levels, calcium and magnesium supplements may be indicated as an adjunctive treatment of fibromyalgia.
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Leung CY, Ng SY, Ho HM. A case of Castleman's disease mimicking a multicystic ovarian tumour. Hong Kong Med J 1999; 5:285-286. [PMID: 11828071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
We report on a case of solitary Castleman's disease that had an unusual presentation. A 29-year-old Filipino woman who had a history of intermittent right lower abdominal pain for several years was admitted to the Princess Margaret Hospital because of a sudden exacerbation of the abdominal pain. Ultrasonography had previously detected a multilocular right ovarian cyst of approximately 6.5 cm in diameter. Intra-operative findings, however, revealed a retroperitoneal presacral cystic tumour of approximately 7 cm in diameter, which was unrelated to the ovaries. The tumour was removed and found to be well defined and measure 7 x 5 x 4 cm. The cut surface revealed homogenous light-brown tissue at the periphery. The central part showed cystic spaces of 1- to 3-cm diameter. Histological examination of the tumour led to the diagnosis of hyaline vascular-type Castleman's disease. Cystic spaces were visible within the infarcted tissue; extensive cystic changes in Castleman's disease are unusual and may have caused the diagnostic difficulty.
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Sintzel MB, Heller J, Ng SY, Tabatabay C, Schwach-Abdellaoui K, Gurny R. In vitro drug release from self-catalyzed poly(ortho ester): case study of 5-fluorouracil. J Control Release 1998; 55:213-8. [PMID: 9795063 DOI: 10.1016/s0168-3659(98)00051-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Self-catalyzed poly(ortho esters) are a new variation of linear poly(ortho esters) prepared by the addition of diols to the diketene acetal 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5,5]undecane where dimer segments of lactic acid or glycolic acid are built into the polymer backbone. By varying the concentration of these segments, polymer erosion rate can be controlled. The present investigation describes the in vitro drug release characteristics from these new polymers. Because poly(ortho esters) have potential applications for the delivery of antifibroblastic agents for example after glaucoma-filtering surgery, the in vitro release studies were evaluated using 5-fluorouracil as the active compound. It was shown that a mole ratio of 90/10 or 80/20 diol/diol-lactate incorporated into the polymer lead to a release of 5-fluorouracil by an erosion process. Smaller amounts of diol-lactate lead to a concomitant drug release by diffusion and erosion. It was also shown that the release rate depends on the alkyl chain length of the diol in the polymer backbone but it does not depend on the drug loading.
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Lo CY, Chu WL, Wan KM, Ng SY, Lee WL, Chu MF, Cheng SW, Lo WK. Pseudomonas exit-site infections in CAPD patients: evolution and outcome of treatment. ARCH ESP UROL 1998; 18:637-40. [PMID: 9932663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
OBJECTIVE To examine the natural history of Pseudomonas aeruginosa (PSA) exit-site infections (ESI) in patients treated with antibiotics with or without surgical interventions. DESIGN Retrospective record review from May 1994 to April 1997. SETTING A single dialysis unit in a district hospital. PATIENTS The review included 353 patients who had undergone continuous ambulatory peritoneal dialysis (CAPD). OUTCOME MEASURES The prevalence and etiology of ESI, the treatment regimen for PSA ESI, and the outcome of treatment. RESULTS The prevalence of ESI was 55%. A total of 131 episodes (range 1-5) of PSA ESI occurred in 78 (40.2%) of the 194 patients who experienced ESI. Among these 78 patients, 4 groups with different outcomes were identified. In group I, 35 patients (44.9%) were treated successfully with antibiotic therapy alone. Among these 35 patients, 4 developed PSA peritonitis at a mean of 5 months (range 2-10 mth) after apparent clinical resolution of PSA ESI. Two of the 4 patients switched to long-term hemodialysis (HD) because of peritoneal failure. In group II, 8 patients (10.3%) responded to a combination of antibiotics and shaving of the external cuff. In group III, 21 patients (26.9%) with recurrent ESI underwent elective Tenckhoff catheter removal and reinsertion. One of the 21 patients had relapse of PSA ESI 14 months after the operation. In group IV, 14 patients (17.9%) had recurrent PSA ESI that failed to respond to multiple courses of antibiotics and shaving of the external cuff. Consent for Tenckhoff catheter removal was not obtained and 4 of these 14 patients subsequently developed PSA peritonitis. One of the 4 patients changed to permanent HD due to peritoneal failure. CONCLUSIONS Considering the increased risk and the poor outcome of PSA peritonitis in patients with persistent PSA ESI, early Tenckhoff catheter removal is recommended if the patient fails to respond to antibiotics with or without externalization of the external cuff.
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Siegel RM, Martin DA, Zheng L, Ng SY, Bertin J, Cohen J, Lenardo MJ. Death-effector filaments: novel cytoplasmic structures that recruit caspases and trigger apoptosis. J Cell Biol 1998; 141:1243-53. [PMID: 9606215 PMCID: PMC2137190 DOI: 10.1083/jcb.141.5.1243] [Citation(s) in RCA: 195] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The death-effector domain (DED) is a critical protein interaction domain that recruits caspases into complexes with members of the TNF-receptor superfamily. Apoptosis can also be induced by expressing certain DED-containing proteins without surface receptor cross-linking. Using Green Fluorescent Protein to examine DED-containing proteins in living cells, we show that these proteins cause apoptosis by forming novel cytoplasmic filaments that recruit and activate pro-caspase zymogens. Formation of these filaments, which we term death-effector filaments, was blocked by coexpression of viral antiapoptotic DED-containing proteins, but not by bcl-2 family proteins. Thus, formation of death-effector filaments allows a regulated intracellular assembly of apoptosis-signaling complexes that can initiate or amplify apoptotic stimuli independently of receptors at the plasma membrane.
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Sintzel MB, Heller J, Ng SY, Taylor MS, Tabatabay C, Gurny R. Synthesis and characterization of self-catalyzed poly(ortho ester). Biomaterials 1998; 19:791-800. [PMID: 9663755 DOI: 10.1016/s0142-9612(97)00229-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Poly(ortho esters) are currently under investigation as a carrier system for an antiproliferative agent in glaucoma filtering surgery. The present investigation illustrates the development of a series of self-catalyzed poly(ortho ester). These polymers contain short dimer segments of alpha-hydroxy acids in their backbone and are prepared by the addition of different polyols to the diketene acetal 3,9-diethylidene-2,4,8,10-tetra-oxaspiro-[5.5]-undecane. The structures were confirmed by NMR- and FT-IR-spectroscopy. The polymers were characterized by determination of the molecular weight, the glass transition temperature and the rheological behavior. The amount of residual solvents was also analyzed. The characteristics of the polymer can be varied by the type of polyol incorporated in its backbone. Since poly(ortho ester) is susceptible to acid-catalyzed degradation, the polymer hydrolysis can be controlled by the amount of incorporated portion of alpha-hydroxy acid. Due to the high hydrophobicity of the polymer structure, the ester bonds are more susceptible to hydrolysis than the ortho ester bonds in the polymer backbone. The hydrolysis proceeds via initial protonation of the exocyclic alkoxy group to yield pentaerythritol dipropionate and the free diol. In a next step, the pentaerythritol dipropionate hydrolysis to pentaerythritol and propionic acid. The molecular weight decrease, weight loss and the pH profile of the polymer in aqueous medium were monitored during the degradation.
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Ng SY, Vandamme T, Taylor MS, Heller J. Controlled drug release from self-catalyzed poly(ortho esters). Ann N Y Acad Sci 1997; 831:168-78. [PMID: 9616710 DOI: 10.1111/j.1749-6632.1997.tb52193.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Brown JE, Escudier MP, Whaites EJ, Drage NA, Ng SY. Intra-oral ultrasound imaging of a submandibular duct calculus. Dentomaxillofac Radiol 1997; 26:252-5. [PMID: 9442619 DOI: 10.1038/sj.dmfr.4600257] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A case is presented showing the first reported use of a small, digitally-guided, intra-oral ultrasound probe to image a calculus in a submandibular salivary duct. This use of intra-oral ultrasound is discussed in the context of the overall current status of intra-oral and extra-oral ultrasound imaging. It is proposed that using a combination of intra-oral and extra-oral probes, the whole of the salivary apparatus may now be examined sonographically for the presence of calculi.
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Hsueh YP, Liang HE, Ng SY, Lai MZ. CD28-costimulation activates cyclic AMP-responsive element-binding protein in T lymphocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1997; 158:85-93. [PMID: 8977178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cyclic AMP-responsive element binding protein (CREB) mediates gene expression in response to cAMP stimulation. The transcriptional activity of CREB depends on both the phosphorylation of Ser133 and the recruitment of cofactor for assembly of transcriptional complex. Extensive Ser133 phosphorylation of CREB was induced during T cell activation. This phosphorylation event is essential for IL-2 gene expression. However, phosphorylation of CREB at Ser133 was not sufficient for transcriptional activity by CREB. The presence of a second signal from CD28, a potent costimulatory molecule on T cells, stimulated CREB-mediated gene expression. CD28, an effective costimulator of T cell activation and IL-2 gene expression, is shown to induce CREB activation in the presence of anti-CD3 or O-tetradecanoylphorbol 13-acetate. These two signals together stimulated a CRE-dependent reporter gene, the proliferating cell nuclear Ag promoter, and transactivation by the GAL4-CREB fusion protein. Thus optimal induction of CREB, similar to the full activation of T lymphocytes, may be mediated by two distinct signal transductions. Using the specific kinase inhibitor, one of the two pathways appeared to involve mitogen-activated protein kinase kinase but not protein kinase C, protein kinase A, or p70 S6 kinase.
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Hsueh YP, Liang HE, Ng SY, Lai MZ. CD28-costimulation activates cyclic AMP-responsive element-binding protein in T lymphocytes. THE JOURNAL OF IMMUNOLOGY 1997. [DOI: 10.4049/jimmunol.158.1.85] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Cyclic AMP-responsive element binding protein (CREB) mediates gene expression in response to cAMP stimulation. The transcriptional activity of CREB depends on both the phosphorylation of Ser133 and the recruitment of cofactor for assembly of transcriptional complex. Extensive Ser133 phosphorylation of CREB was induced during T cell activation. This phosphorylation event is essential for IL-2 gene expression. However, phosphorylation of CREB at Ser133 was not sufficient for transcriptional activity by CREB. The presence of a second signal from CD28, a potent costimulatory molecule on T cells, stimulated CREB-mediated gene expression. CD28, an effective costimulator of T cell activation and IL-2 gene expression, is shown to induce CREB activation in the presence of anti-CD3 or O-tetradecanoylphorbol 13-acetate. These two signals together stimulated a CRE-dependent reporter gene, the proliferating cell nuclear Ag promoter, and transactivation by the GAL4-CREB fusion protein. Thus optimal induction of CREB, similar to the full activation of T lymphocytes, may be mediated by two distinct signal transductions. Using the specific kinase inhibitor, one of the two pathways appeared to involve mitogen-activated protein kinase kinase but not protein kinase C, protein kinase A, or p70 S6 kinase.
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Ng SY, Morgan M. Candida peritonitis treated with liposomal amphotericin B. Postgrad Med J 1996; 72:636-7. [PMID: 8977956 PMCID: PMC2398586 DOI: 10.1136/pgmj.72.852.636-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Liu JJ, Chao JR, Jiang MC, Ng SY, Yen JJ, Yang-Yen HF. Ras transformation results in an elevated level of cyclin D1 and acceleration of G1 progression in NIH 3T3 cells. Mol Cell Biol 1995; 15:3654-63. [PMID: 7791772 PMCID: PMC230603 DOI: 10.1128/mcb.15.7.3654] [Citation(s) in RCA: 231] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Ectopic overexpression of v-H-Ras protein in NIH 3T3 cells resulted in cellular transformation and an acceleration of G1 progression of these cells. A shortened G1 phase was found to be associated with an increased level of cyclin D1 but not cyclin E protein. Using an antisense blocking method, reduced synthesis of cyclin D1 in v-H-Ras transformants resulted in a slower G1 progression rate of these cells. Although constitutive overexpression of cyclin D1 in NIH 3T3 cells accelerated G1 progression, cells remained untransformed. Furthermore, inhibition of cyclin D1 synthesis greatly impaired the soft-agar cloning efficiency of v-H-Ras transformants. These results suggest that increased expression of cyclin D1 is necessary but not sufficient for the transforming activity of v-H-Ras. Similar effect on cell cycle progression was also observed in Raf-transformed cells. In addition to cyclin D1, cyclin E protein was found to be elevated in Src transformants. This may account for the further shortening of the G1 phase of these cells. Activation of an additional Ras-independent pathway was suggested to be responsible for the further acceleration of the G1 phase in Src transformants.
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Liu SH, Peng BH, Ma JT, Liu YC, Ng SY. Serum response element associated transcription factors in mouse embryos: serum response factor, YY1, and PEA3 factor. DEVELOPMENTAL GENETICS 1995; 16:229-40. [PMID: 7796532 DOI: 10.1002/dvg.1020160303] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Many mammalian transcription factors, including human and mouse serum response factors (SRFs), are post-translationally modified with O-linked N-acetylglucosamine monosaccharides on multiple serine and/or threonine residues. Nuclear extracts were prepared from 9.5 to 19 days postcoitum mouse embryos and subsequently were fractionated by wheat germ agglutinin (WGA)-agarose affinity chromatography. SRF binds WGA-agarose and apparently is O-glycosylated. On the other hand, the low molecular weight serum response element (SRE)-binding proteins, including the previously named band I and band II factors, did not bind WGA-agarose. Furthermore, we showed that the fastest migrating complex contains the Yin-Yang 1 (YY1) factor. YY1 binds to the c-fos SRE and skeletal alpha-actin muscle regulatory element (MRE), but not the cardiac alpha-actin MRE. Nuclear extracts from NIH/3T3 fibroblasts contain similar, if not identical, SRE-binding complexes. Besides these SRE-binding factors, mouse PEA3-binding factor, presumably an ETS domain-containing protein, was found to bind SRF protein. This physical interaction, between SRF and ETS domain proteins, was shown to involve the DNA-binding domain-containing region of SRF and not the carboxyl-terminal transactivation domain.
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Lee HH, Chiang WH, Chiang SH, Liu YC, Hwang J, Ng SY. Regulation of cyclin D1, DNA topoisomerase I, and proliferating cell nuclear antigen promoters during the cell cycle. Gene Expr 1995; 4:95-109. [PMID: 7734951 PMCID: PMC6134377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/1994] [Accepted: 07/21/1994] [Indexed: 01/26/2023]
Abstract
Cyclin D1, DNA topoisomerase I, and proliferating cell nuclear antigen (PCNA) are three important cell cycle regulatory proteins. Recently, their promoters have been isolated, thus facilitating molecular analysis of transcriptional control mechanisms of these genes. Transcription of these three promoters in stable K562 transfectants during different cell cycle phases was analyzed after cell cycle synchronization. About 1 kb of 5' flanking region from either cyclin D1 or DNA topoisomerase I gene is sufficient to confer G1- or S-phase-specific transcription activity to chloramphenicol acetyltransferase (CAT) reporter genes, respectively. In contrast, 2.8 kb of 5' flanking sequences from the PCNA gene led to constitutive transcription, but the inclusion of a segment of the PCNA gene first intron, which contains evolutionarily conserved sequences, could enhance transcription in G1/S-enriched nuclei. This PCNA intron region contains a binding site recognized by the transcription factor E2F. To test whether this site is functional, we cotransfected PCNA-CAT genes with E2F-1 and DP-1 expression plasmids. Expression of the E2F-1/DP-1 heterodimer activated the CAT gene with the PCNA intron. Therefore, this intron region, involved in transcriptional activation at the cell cycle G1/S boundary, is also E2F inducible.
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Liu SH, Ng SY. Serum response factor associated ETS proteins: ternary complex factors and PEA3-binding factor. Biochem Biophys Res Commun 1994; 201:1406-13. [PMID: 8024585 DOI: 10.1006/bbrc.1994.1860] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
An ETS protein binding motif CAGGAT adjoins the 5' side of the Serum Response Element in the c-fos promoter. This sequence is recognized by several ETS proteins which are able to form ternary complexes in the presence of Serum Response Factor. Related sequences, capable of ternary complex formation, are also found in the promoters of immediate early zinc finger proteins. However, similar sequences found in the gamma-actin and c-ets-2 promoters could not bind Ternary Complex Factor. We purified a 60-kDa human ETS protein which could bind the sequence recognized by Ternary Complex Factor, and this protein could bind DNA in the absence of Serum Response Factor. Interestingly, this protein also binds Serum Response Factor in vitro. Therefore the Serum Response Factor DNA-binding/oligomerization domain has affinities for distinct ETS oncoproteins.
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Chuang CF, Ng SY. Functional divergence of the MAP kinase pathway. ERK1 and ERK2 activate specific transcription factors. FEBS Lett 1994; 346:229-34. [PMID: 8013639 DOI: 10.1016/0014-5793(94)00480-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Growth factor-receptor interactions at the cell surface eventually leading to the transcriptional activation of immediate early genes is mediated by the mitogen-activated protein kinase (MAP kinase/MAPK) cascade. Here we show that overexpression of extracellular signal-regulated kinase 1 (ERK1) cDNA, encoding p44mapk, results in the activation of Elk-1, the serum response factor accessory protein. We also show that overexpression of ERK2, encoding p42mapk, activates Myc, but not Elk-1. Therefore, the MAP kinase cascade diverges with at least one specific target for each MAP kinase isoform and provides a novel mechanism for differential regulation of this signaling pathway.
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