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Dedhar S, Troussard A, Tan C. 136 Regulation of tumour angiogenesis and cell survival by integrin-linked kinase (ILK): pre-clinical evaluation of novel small molecule inhibitors. EJC Suppl 2004. [DOI: 10.1016/s1359-6349(04)80143-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Tan C, Yang Y, Boyer A, Xing L. Enhancing the efficacy of radiation therapy by incorporating spatial distribution of heterogeneous biology. Int J Radiat Oncol Biol Phys 2004. [DOI: 10.1016/j.ijrobp.2004.07.190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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203
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Tan EK, Zhao Y, Puong KY, Law HY, Chan LL, Yew K, Tan C, Shen H, Chandran VR, Teoh ML, Yih Y, Pavanni R, Wong MC, Ng IS. Fragile X premutation alleles in SCA, ET, and parkinsonism in an Asian cohort. Neurology 2004; 63:362-3. [PMID: 15277639 DOI: 10.1212/01.wnl.0000130199.57181.7b] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Among 367 subjects, the authors analyzed 167 patients with essential tremor, sporadic progressive cerebellar ataxia, multiple-system atrophy, and atypical parkinsonism and 200 healthy control subjects for FMR1 premutation alleles. None of the subjects carried alleles within the premutation range. These findings suggest that in the absence of other supportive clinical or imaging features, the cost-effectiveness of routine fragile X tremor/ataxia syndrome screening in this Asian cohort with movement disorders was low.
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Lee CGL, Tang K, Cheung YB, Wong LP, Tan C, Shen H, Zhao Y, Pavanni R, Lee EJD, Wong MC, Chong SS, Tan EK. MDR1, the blood-brain barrier transporter, is associated with Parkinson's disease in ethnic Chinese. J Med Genet 2004; 41:e60. [PMID: 15121788 PMCID: PMC1735769 DOI: 10.1136/jmg.2003.013003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Tan C, Govendir M, Zaki S, Miyake Y, Packiarajah P, Malik R. Evaluation of four warming procedures to minimise heat loss induced by anaesthesia and surgery in dogs. Aust Vet J 2004; 82:65-8. [PMID: 15088962 DOI: 10.1111/j.1751-0813.2004.tb14646.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To evaluate the efficiency of four warming procedures, introduced after anaesthetic induction and continued during surgery, in minimising heat loss in anaesthetised dogs. DESIGN Dogs were paired. One of each pair was a control; the other was subjected to one of four warming procedures. METHODS Ninety-six dogs were involved in total. Pairs of dogs were matched for breed, hair length, and type of surgical procedure and placed adjacent to each other in a large temperature-controlled surgical theatre. One dog within each pair was assigned to one of four warming procedures that commenced immediately after anaesthetic induction. Group 1 (11 pairs) were placed on a purpose-designed prewarmed (41 degrees C) electrically heated pad. Group 2 (18 pairs) were placed on a prewarmed electric heat pad (41 degrees C), cocooned by four wrapped water bottles (initially 41 degrees C) and subjected to radiant heat (150 watt lamp placed 50 cm away from the head of the dog). Group 3 (11 pairs) were surrounded by a forced air warming mattress (set at 43 degrees C). Group 4 (8 pairs) were connected via the anaesthetic breathing circuit to a heater/humidifier (set at 41 degrees C). Rectal temperature measurements were recorded every 15 min for the first 3 h of anaesthesia. The fall in rectal temperature of the control dog was subtracted from the fall in temperature of the treatment dog and this measurement was used to assess the efficacy of the various warming procedures. RESULTS The mean rectal temperature of unheated 'control' dogs decreased 1.9 +/- 0.6, 1.4 +/- 0.4 and 1.1 +/- 0.4 degrees C over the first, second and third hour respectively. After 3 h the temperature fall differential for all groups were 0.7 +/- 0.7 (Group 1), 3.1 +/- 1.1 (Group 2), 2.4 +/- 1.1 (Group 3) and 1.0 +/- 1.1 degrees C (Group 4). Thus the group 2 procedure was the most successful in preventing a drop of temperature followed by groups 3, 4 and 1. CONCLUSION Large dogs undergo significant reduction in core body temperature especially during the first 2 h of anaesthesia and surgery. Supplementary warming substantially reduces this fall in body temperature, although certain warming procedures were found to be more effective than others.
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Tan EK, Chai A, Teo YY, Zhao Y, Tan C, Shen H, Chandran VR, Teoh ML, Yih Y, Pavanni R, Wong MC, Puvan K, Lo YL, Yap E. Alpha-synuclein haplotypes implicated in risk of Parkinson's disease. Neurology 2004; 62:128-31. [PMID: 14718715 DOI: 10.1212/01.wnl.0000101721.25345.dc] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The authors examined four- and six-loci haplotype constructs (from five single nucleotide polymorphisms and three microsatellite regions) of the alpha-synuclein gene in patients with Parkinson's disease (PD) and controls in an ethnic Chinese population. Logistic regression analysis demonstrated an association of NACP-Rep1 (p = 0.002) and L478 (p < 0.0001) with risk of PD after correction for the effects of age, sex, and the other polymorphic loci. Specific four-loci and six-loci haplotypes were significantly associated with an increased or decreased risk of PD.
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Tan C, Straatman L. 209 WHAT DO PHYSICIANS WANT TO KNOW AND HAVE WHEN WORKING WITH PEDIATRIC END-OF-LIFE PATIENTS AND THEIR FAMILIES? J Investig Med 2004. [DOI: 10.1136/jim-52-suppl1-209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Tan EK, Tan C, Fook-Chong SMC, Lum SY, Chai A, Chung H, Shen H, Zhao Y, Teoh ML, Yih Y, Pavanni R, Chandran VR, Wong MC. Dose-dependent protective effect of coffee, tea, and smoking in Parkinson's disease: a study in ethnic Chinese. J Neurol Sci 2003; 216:163-7. [PMID: 14607318 DOI: 10.1016/j.jns.2003.07.006] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Few studies have examined the relationship of coffee and tea in Parkinson's disease (PD). The potential protective effect of coffee intake and risk of PD has not been studied in a Chinese population. There is a high prevalence of caffeine takers among Chinese in our population. OBJECTIVE We undertook a case control study to examine the relationship between coffee and tea drinking, cigarette smoking, and other enviromental factors and risk of PD among ethnic Chinese in our population. METHODS AND RESULTS 300 PD and 500 population controls were initially screened. Two hundred case control pairs matched for age, gender, and race were finally included in the analysis. Univariate analysis revealed significant association of PD with coffee drinking (p<0.0005), tea drinking (p=0.019), alcohol drinking (p=0.001), cigarette smoking (p<0.0005), and exposure to heavy metals (p=0.006). Conditional logistic regression analysis demonstrated that amount of coffee drunk (OR 0.787, 95%CI 0.664-0.932, p=0.006), amount of tea drunk (OR 0.724, 95%CI 0.559-0.937, p=0.014), number of cigarettes smoked (OR 0.384, 95%CI 0.204-0.722, p=0.003), history of heavy metal and toxin exposure (OR 11.837, 95%CI 1.075-130.366, p=0.044), and heart disease (OR 5.518, 95%CI 1.377-22.116, p=0.016) to be significant factors associated with PD. One unit of coffee and tea (3 cups/day for 10 years) would lead to a 22% and 28% risk reduction of PD. One unit of cigarette smoke (3 packs/day for 10 years) reduced the risk of PD by 62%. CONCLUSIONS We demonstrated a dose-dependent protective effect of PD in coffee and tea drinkers and smokers in an ethnic Chinese population. A history of exposure to heavy metals increased the risk of PD, supporting the multifactorial etiologies of the disease.
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Wu XL, Xiong SJ, Siu GG, Huang GS, Mei YF, Zhang ZY, Deng SS, Tan C. Optical emission from excess Si defect centers in Si nanostructures. PHYSICAL REVIEW LETTERS 2003; 91:157402. [PMID: 14611493 DOI: 10.1103/physrevlett.91.157402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2002] [Indexed: 05/24/2023]
Abstract
Four groups of Si nanostructures with and without beta-SiC nanocrystals were fabricated for clarifying the origin of a blue emission with a double-peak structure at 417 and 436 nm. Spectral analyses and microstructural observations show that the blue emission is related to the existence of excess Si atoms in these Si nanostructures. The energy levels of electrons in Si nanocrystals with vacancy defects formed from the excess Si atoms are calculated and the characteristics of the obtained density of states coincide with the observed double-peak emission. The present work provides a possible mechanism of the blue emission in various Si nanostructures.
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Rupert JL, Monsalve MV, Kidd KK, Tan C, Hochachka PW, Devine DV. Selective pressure has not acted against hypercoagulability alleles in high-altitude Amerindians. Ann Hum Genet 2003; 67:426-32. [PMID: 12940916 DOI: 10.1046/j.1469-1809.2003.00043.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Elevated hematocrit increases blood oxygen carrying capacity in high-altitude populations, but blood viscosity and coaguability may increase concomitantly. Alleles of the beta-fibrinogen gene (FGB) associated with lower fibrinogen levels are more common in highland Amerindians (Quechua) than lowland Amerindians (Na-Dene). Although genetic drift could account for this, selection may have acted against transmission of hypercoagulability alleles at high altitude. To test this hypothesis, we compared allele frequencies between Quechua and more closely related lowlanders (Maya) at loci in the genes encoding beta-fibrinogen (FGB), factors V (F5), VII (F7) and XIII (F13), alpha2-integrin (ITGA2) and plasminogen activator inhibitor type 1 (PAI-1; SERPINE1). No significant differences in allele frequencies were found except 485arg in the gene encoding factor V, which was more common in the Quechua. These data do not support the hypothesis that selection has acted to eliminate alleles associated with hypercoagulability in Andean highlanders.
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Tan EK, Chai A, Lum SY, Shen H, Tan C, Teoh ML, Yih Y, Wong MC, Zhao Y. Monoamine oxidase B polymorphism, cigarette smoking and risk of Parkinson's disease: a study in an Asian population. Am J Med Genet B Neuropsychiatr Genet 2003; 120B:58-62. [PMID: 12815741 DOI: 10.1002/ajmg.b.20035] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cigarette smoking is associated with reduced monoamine oxidase B (MAO B) activity. Polymorphisms of the MAO B gene may modify the relationship between smoking and Parkinson's Disease (PD). We examined the association of MAO B intron 13 G/A polymorphism and risk of PD, and the modulation of the polymorphism on smoking and PD in an Asian study population in Singapore. Two hundred and thirty PD patients (mean age 66.0 +/- 9.4 years, 63% men) and 241 age, gender, and race matched controls (mean age 64 +/- 9.2 years, 58.9% males) were studied. The frequency of G and A alleles in PD and controls was; 66/315 (21.0%) vs. 73/340 (21.5%) and 249/315 (79.0%) vs. 267/340 (78.5%). For women, the genotype frequency in PD and controls was; GG: 7/85 (8.2%) vs. 8/99 (8.1%); GA: 25/85 (29.4%) vs. 27/99 (27.3%); AA: 53/85 (62.4%) vs. 64/99 (64.6%). For men, allele frequency in PD and controls was; A: 118/145 (81.4%) vs. 112/142 (78.9%) and G: 27/145 (18.6%) vs. 30/142 (21.1%). The allele and genotype frequencies were not significantly different between young and late onset PD. The frequency of "ever" smokers in PD and controls was 31/230 (13.5%) vs. 52/241 (21.6%), P = 0.02. A stepwise logistic regression analysis did not reveal any interaction of smoking and the G allele and risk of PD. The MAO B G/A genotype frequency in our Asian population was quite different from Caucasians suggesting that ethnicity specific effects need to be considered in evaluating gene-environmental interaction.
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Mak KH, Chia KS, Kark JD, Chua T, Tan C, Foong BH, Lim YL, Chew SK. Ethnic differences in acute myocardial infarction in Singapore. Eur Heart J 2003; 24:151-60. [PMID: 12573272 DOI: 10.1016/s0195-668x(02)00423-2] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
AIMS We compare the myocardial infarction (MI) event and mortality rates among Chinese, Malay and Indian residents of Singapore. METHODS Residents, aged 20 to 64 years, with an MI event were identified from hospital discharge listings, postmortem reports, and the Registry of Births and Deaths. All pathology laboratories flagged patients with elevated creatine phosphokinase (CPK) levels. Modified MONICA (multinational monitoring of trends and determinants in cardiovascular disease) criteria were used for determining MI events. RESULTS From 1991 to 1999, 12 481 MI events were identified. Chinese patients were older and less likely to have typical symptoms or previous MI. Malays had the highest peak CPK level. Among all three ethnic groups, MI event and age-adjusted case-fatality rates declined. Compared with Chinese, MI event rates were >2-fold and >3-fold higher, and age-standardized coronary mortality rates were 2.4 and 3.0 higher times for Malays and Indians, respectively. Malays have the highest 3.1-year case-fatality, with an adjusted hazard ratio of 1.26 (95% confidence interval, 1.14 to 1.38) compared with Chinese. CONCLUSION We found strong ethnic differences in MI event, case-fatality and coronary mortality rates among the three ethnic groups in Singapore. While Indians have the greatest MI event rates, Malays have the highest case-fatality.
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Ongtengco I, Morales D, Sanderson J, Lu ZR, Beilin LJ, Burke V, Puddey IB, Tanomsup S, Dayi H, Rahardjo P, Zambahari DR, Chen CY, Soenarta AA, Buranakitjaroen P, Tan C, Soon TK, Wu DJ. Persistence of the antihypertensive efficacy of amlodipine and nifedipine GITS after two 'missed doses': a randomised, double-blind comparative trial in Asian patients. J Hum Hypertens 2002; 16:805-13. [PMID: 12444542 DOI: 10.1038/sj.jhh.1001485] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Suboptimal management of hypertension is often a result of poor patient compliance in the form of missed doses of their antihypertensive medication. This multicentre, randomised, double-blind, parallel-group trial was designed to compare the persistence of the antihypertensive efficacy of the amlodipine and nifedipine gastrointestinal therapeutic system (GITS) after two 'missed doses', and also to compare the drugs' overall efficacy and safety in Asian patients with mild-to-moderate essential hypertension. Following a 2-week placebo run-in period, 222 patients were randomised to receive either amlodipine (5 mg daily, increased after 6 weeks if necessary to 10 mg daily, n=109) or nifedipine GITS (30 mg daily, increased after 6 weeks if necessary to 60 mg daily; n=113) for 12 weeks. A placebo was then substituted for further 2 days with continuous ambulatory blood pressure (BP) monitoring. The increases in the last 9 h of mean ambulatory BP on day 2 after treatment withdrawal were significantly less with amlodipine than with nifedipine GITS: 4.4+/-7.0 vs 11.2+/-11.3 mmHg for systolic BP (P<or=0.0001) and 2.4+/-6.3 vs 6.0+/-6.0 mmHg for diastolic BP (P<or=0.0002). Significant differences between the two drugs in mean 24-h ambulatory BP levels were already evident on day 1 after withdrawal, even though there were no significant differences on the final day of treatment. No differences in safety parameters were observed, and neither drug caused any serious or severe treatment-related adverse events. In conclusion, amlodipine provides greater protection than nifedipine GITS against loss of BP control following missed doses.
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Xu J, Chen Z, Yu JC, Tan C. Simultaneous determination of inorganic anions, carboxylic and aromatic carboxylic acids by capillary zone electrophoresis with direct UV detection. J Chromatogr A 2002; 942:289-94. [PMID: 11822394 DOI: 10.1016/s0021-9673(01)01402-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Co-electroosmotic capillary zone electrophoresis (CZE) with direct UV detection was developed for simultaneous determination of inorganic anions, carboxylic and aromatic carboxylic acids. These solutes were separated using a 30 mM phosphate buffer containing 1.0 mM tetradecyltrimethylammonium bromide (TTAB) and 20% (v/v) acetonitrile at pH of 6.5 and directly detected by UV at 190 nm. Calibration curves were linear in the range 0.01-2.0 mM, depending of the solutes. The detection limits ranged from 1.0 to 8.0 microM and the relative standards deviations (n=5) in range from 1.9 to 3.6% for the peak area. The proposed method was used to determine inorganic anions and carboxylic and aromatic acids in soil and plant tissue extracts.
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Brzeska H, Young R, Tan C, Szczepanowska J, Korn ED. Calmodulin-binding and autoinhibitory domains of Acanthamoeba myosin I heavy chain kinase, a p21-activated kinase (PAK). J Biol Chem 2001; 276:47468-73. [PMID: 11579107 DOI: 10.1074/jbc.m108957200] [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: 11/06/2022] Open
Abstract
The sequence homology between Acanthamoeba myosin I heavy chain kinase (MIHCK) and other p21-activated kinases (PAKs) is relatively low, including only the catalytic domain and a short PAK N-terminal motif (PAN), and even these regions are not highly homologous. In this paper, we report the expression in insect cells of full-length, fully regulated Acanthamoeba MIHCK and further characterize the regulation of this PAK by Rac, calmodulin, and autoinhibition. We map the autoinhibitory region of MIHCK to its PAN region and show that the PAN region inhibits autophosphorylation and kinase activity of unphosphorylated full-length MIHCK and its expressed catalytic domain but has very little effect on either when they are phosphorylated. These properties are similar to those reported for mammalian PAK1. Unlike PAK1, MIHCK is activated by Rac only in the presence of phospholipid. However, peptides containing the PAN region of MIHCK bind Rac in the absence of lipid, and Rac binding reverses the inhibition of the MIHCK catalytic domain by PAN peptides. Our data suggest that a region N-terminal to PAN is required for optimal binding of Rac. Also unlike mammalian PAK, phospholipid stimulation of Acanthamoeba MIHCK and Dictyostelium MIHCK) (which is also a PAK) is inhibited by Ca(2+)-calmodulin. In contrast to Dictyostelium MIHCK, however, Ca(2+)-calmodulin also inhibits Rac-induced activity of Acanthamoeba MIHCK. The basic region N-terminal to PAN is essential for calmodulin binding.
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Shi LJ, Wu JL, Li GD, Tan C, Song L, Yan GD. [Hemodynamics following + Gz stress in dog]. ZHONGGUO YING YONG SHENG LI XUE ZA ZHI = ZHONGGUO YINGYONG SHENGLIXUE ZAZHI = CHINESE JOURNAL OF APPLIED PHYSIOLOGY 2001; 17:376-378. [PMID: 21207706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
AIM To investigate the character of hemodynamics following + Gz stress in dog. METHODS Nine anesthesia dogs were exposed to 5, 7 and 9 + Gz stress, 90 s at peak G. Each animal was instrumented to measure left ventricular pressure, thoracic aorta pressure, iliac arterial pressure,common carotid artery flow (CCAF) and ECG. RESULTS (1) Heart rate, CCAF and blood pressure at any place increased. They were greater than those before + Gz stress (P < 0.05). (2) There were much more arrhythmias following high + Gz stress. Most of arrhythmias were junctional premature beats, ventricular premature beats. 80% arrhythmias occurred within 3 min following + Gz stress. (3) Blood pressure appeared the highest in the second min following + Gz stress. CONCLUSION Great hemodynamic disturbance happened following high + Gz stress. There might were reperfusion arrhythmias. Protective measures should been noted following high + Gz stress.
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Li N, Zhao B, Tan C. [Intramandibular course and anatomic structure of the inferior alveolar nerve canal]. ZHONGHUA KOU QIANG YI XUE ZA ZHI = ZHONGHUA KOUQIANG YIXUE ZAZHI = CHINESE JOURNAL OF STOMATOLOGY 2001; 36:446-7. [PMID: 11930722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
OBJECTIVE To study the intramandibular course and anatomic structure of mandibular canal. METHODS The intramandibular course of mandibular canal and its dimension were measured in 15 adults mandibles with teeth; the relationship between blood vessel and nerve was observed in 4 fresh samples in which the artery was filled. RESULTS The mandibular canal was close to the lingual side and the inferior margin of the mandible. The blood vessel lay above nerve in the mandibular canal. CONCLUSIONS In implant operation performed according to normal anatomy, injury to inferior alveolar nerve may be avoided. Hemorrhage is the earliest manifestation suggesting that continuing drill may damage the inferior alveolar nerve.
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Deardorff MA, Tan C, Saint-Jeannet JP, Klein PS. A role for frizzled 3 in neural crest development. Development 2001; 128:3655-63. [PMID: 11585792 DOI: 10.1242/dev.128.19.3655] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Wnts are a large family of secreted molecules implicated in numerous developmental processes. Frizzled proteins are likely receptors for Wnts and are required for Wnt signaling in invertebrates. A large number of vertebrate frizzled genes have also been identified, but their roles in mediating specific responses to endogenous Wnts have not been well defined. Using a functional assay in Xenopus, we have performed a large screen to identify potential interactions between Wnts and frizzleds. We find that signaling by Xwnt1, but not other Wnts, can be specifically enhanced by frizzled 3 (Xfz3). As both Xfz3 and Xwnt1 are highly localized to dorsal neural tissues that give rise to neural crest, we examined whether Xfz3 mediates Xwnt1 signaling in the formation of neural crest. Xfz3 specifically induces neural crest in ectodermal explants and in embryos, similar to Xwnt1, and at lower levels of expression, synergizes with Xwnt1 in neural crest induction. Furthermore, loss of Xfz3 function, either by depletion with a Xfz3-directed morpholino antisense oligonucleotide or by expression of an inhibitory form of Xfz3 (Nfz3), prevents Xwnt1-dependent neural crest induction in ectodermal explants and blocks neural crest formation in whole embryos. These results show that Xfz3 is required for Xwnt1 signaling in the formation of the neural crest in the developing vertebrate embryo.
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Tan C, Deardorff MA, Saint-Jeannet JP, Yang J, Arzoumanian A, Klein PS. Kermit, a frizzled interacting protein, regulates frizzled 3 signaling in neural crest development. Development 2001; 128:3665-74. [PMID: 11585793 DOI: 10.1242/dev.128.19.3665] [Citation(s) in RCA: 49] [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
Wnts are a family of secreted glycoproteins that are important for multiple steps in early development. Accumulating evidence suggests that frizzled genes encode receptors for Wnts. However, the mechanism through which frizzleds transduce a signal and the immediate downstream components that convey that signal are unclear. We have identified a new protein, Kermit, that interacts specifically with the C-terminus of Xenopus frizzled-3 (Xfz3). Kermit is a 331 amino acid protein with a central PDZ domain. Kermit mRNA is expressed throughout Xenopus development and is localized to neural tissue in a pattern that overlaps Xfz3 expression temporally and spatially. Co-expression of Xfz3 and Kermit results in a dramatic translocation of Kermit to the plasma membrane. Inhibition of Kermit function with morpholino antisense oligonucleotides directed against the 5′ untranslated region of Kermit mRNA blocks neural crest induction by Xfz3, and this is rescued by co-injection of mRNA encoding the Kermit open reading frame. These observations suggest that Kermit is required for Wnt/frizzled signaling in neural crest development. To the best of our knowledge, Kermit is the first protein identified that interacts directly with the cytoplasmic portion of frizzleds to modulate their signaling activity.
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Marotta A, Tan C, Gray V, Malik S, Gallinger S, Sanghera J, Dupuis B, Owen D, Dedhar S, Salh B. Dysregulation of integrin-linked kinase (ILK) signaling in colonic polyposis. Oncogene 2001; 20:6250-7. [PMID: 11593435 DOI: 10.1038/sj.onc.1204791] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2001] [Revised: 06/26/2001] [Accepted: 07/05/2001] [Indexed: 12/21/2022]
Abstract
Mutation of the adenomatous polyposis coli (APC) gene and the subsequent dysregulation of beta-catenin are well-documented abnormalities in familial adenomatous polyposis (FAP), as well as sporadic polyposis. Intriguingly, overexpression of the integrin-linked kinase (ILK) has been shown to modulate beta-catenin subcellular localization and function. However, the significance of this finding for human carcinogenesis remains unclear. Here, we report the increased biochemical activity and expression of ILK protein in polyps from FAP patients. Furthermore, dramatic increases in ILK immunoreactivity were observed in all abnormal crypts from sporadic polyps, when compared with the normal appearing crypts within the same resected specimens. As sulindac and aspirin are the two most important therapeutic/chemopreventative agents demonstrated in colorectal carcinogenesis, in both humans and animals, further investigation revealed that these non-steroidal anti-inflammatory drugs (NSAIDs) target ILK and ILK-mediated events in vivo. These include inhibition of, both the biochemical activation of ILK, inhibition of serine 9 GSK3beta phosphorylation and the enhancement of TCF-4 transcriptional activity. In conclusion, ILK protein hyperexpression appears to be an early event in colonic polyposis. Additionally, ILK signaling is shown to undergo modulation by sulindac (and aspirin) for the first time, indicating that it is likely to be one of the targets affected by these agents in vivo.
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Palucki BL, Feighner SD, Pong S, McKee KK, Hreniuk DL, Tan C, Howard AD, Van der Ploeg LH, Patchett AA, Nargund RP. Spiro(indoline-3,4'-piperidine) growth hormone secretagogues as ghrelin mimetics. Bioorg Med Chem Lett 2001; 11:1955-7. [PMID: 11459669 DOI: 10.1016/s0960-894x(01)00324-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A series of small molecules derived from MK-0677, a potent synthetic GHS, mimicking the N-terminal Gly-Ser-O-(n-octanoyl)-L-Ser-Phe segment of ghrelin was synthesized and tested in a binding and in a functional assay measuring intracellular calcium elevation in HEK-293 cells expressing hGHSR1a. Replacement of Phe in this tetrapeptide with a spiro(indoline-3,4'-piperidine) group, Gly-Ser with 2-aminoisobutyric acid, and O-(n-octanoyl)-L-Ser with O-benzyl-D-Ser provided synthetic GHS agonists with similar functional potency as ghrelin.
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Li J, Tan C, Xiang Q, Zhang X, Ma J, Wang JR, Yang J, Li W, Shen SR, Liang S, Li G. Proteomic detection of changes in protein synthesis induced by NGX6 transfected in human nasopharyngeal carcinoma cells. JOURNAL OF PROTEIN CHEMISTRY 2001; 20:265-71. [PMID: 11565907 DOI: 10.1023/a:1010912311564] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In the previous study, we cloned a new gene, named NGX6, related to nasopharyngeal carcinoma (NPC) at 9p. To study its function in the pathogenesis of NPC, we have investigated changes in protein synthesis between NPC cell line HNE1 and that transfected with the gene. Using high-resolution two-dimensional electrophoresis, we found that 22 protein spots showed variations that were significant and reproducible. Analysis of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and database searches identified seven proteins that were upregulated and seven proteins that were downregulated. These proteins included Fas, zinc-finger protein (ZNF), RAB, and Ah receptor-interacting protein (AIP). The functional implications of the identified proteins are discussed.
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Rasmussen JT, Deardorff MA, Tan C, Rao MS, Klein PS, Vetter ML. Regulation of eye development by frizzled signaling in Xenopus. Proc Natl Acad Sci U S A 2001; 98:3861-6. [PMID: 11274406 PMCID: PMC31143 DOI: 10.1073/pnas.071586298] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eye development in both invertebrates and vertebrates is regulated by a network of highly conserved transcription factors. However, it is not known what controls the expression of these factors to regulate early eye formation and whether transmembrane signaling events are involved. Here we establish a role for signaling via a member of the frizzled family of receptors in regulating early eye development. We show that overexpression of Xenopus frizzled 3 (Xfz3), a receptor expressed during normal eye development, functions cell autonomously to promote ectopic eye formation and can perturb endogenous eye development. Ectopic eyes obtained with Xfz3 overexpression have a laminar organization similar to that of endogenous eyes and contain differentiated retinal cell types. Ectopic eye formation is preceded by ectopic expression of transcription factors involved in early eye development, including Pax6, Rx, and Otx2. Conversely, targeted overexpression of a dominant-negative form of Xfz3 (Nxfz3), consisting of the soluble extracellular domain of the receptor, results in suppression of endogenous Pax6, Rx, and Otx2 expression and suppression of endogenous eye development. This effect can be rescued by coexpression of Xfz3. Finally, overexpression of Kermit, a protein that interacts with the C-terminal intracellular domain of Xfz3, also blocks endogenous eye development, suggesting that signaling through Xfz3 or a related receptor is required for normal eye development. In summary, we show that frizzled signaling is both necessary and sufficient to regulate eye development in Xenopus.
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Tan C, Chang L, Shen S, Liu DX, Kwang J. Comparison of the 5' leader sequences of North American isolates of reference and field strains of porcine reproductive and respiratory syndrome virus (PRRSV). Virus Genes 2001; 22:209-17. [PMID: 11324758 PMCID: PMC7088843 DOI: 10.1023/a:1008179726163] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The 5' leader is documented to be an important regulatory element in many (+) ssRNAvirus genome. To understand the significance of the 5' leader RNA of PRRSV, we determined the complete leader sequences of fifteen different North American strains of PRRSV and predicted their secondary structures. Viruses analysed included three reference strains and nine field strains originating from different geographic locations. To further examine the leader region, one of the field strains was adapted to grow in tissue culture, and three clones were isolated. We also predicted the secondary structures of two European strains based on their published sequences. The predicted RNA secondary structures of the leader sequences suggested the existence of three conserved domains formed by the 5' region of the leader among the North American strains, two of which were conserved in the European strains. A variable structural domain was predicted from the 3' region of the leader sequences of the North American strains, where all tissue culture-adapted isolates were characterized by a stem-loop while field isolates were characterized by an internal bulge within the stem-loop.
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Smith RG, Leonard R, Bailey AR, Palyha O, Feighner S, Tan C, Mckee KK, Pong SS, Griffin P, Howard A. Growth hormone secretagogue receptor family members and ligands. Endocrine 2001; 14:9-14. [PMID: 11322507 DOI: 10.1385/endo:14:1:009] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have previously reported the cloning and characterization of a new orphan G-protein-coupled receptor (GPC-R), the growth hormone secretagogue receptor (GHS-R), and shown that this receptor mediates the activity of the growth hormone-releasing peptides (GHRPs) and nonpeptide ligands such as L-692,429 and MK-0677. Because the GHS-R obviously does not belong to any of the known GPC-R subfamilies, we searched for GHS-R family members by screening a human genomic library using low-stringency hybridization and screening a Pufferfish genomic library. The Pufferfish was selected because of its compact genome. From the human genomic library, a homolog, GPR38, with 52% identity to the GHS-R was isolated. From the Pufferfish library, three family members were isolated. The Pufferfish gene having 58% identity to the GHS-R, on expression in HEK293 cells, was activated with GHRP-6 and MK-0677. These results indicate that the GHS-R has been conserved for at least 400 million years and that the Pufferfish genome is appropriate for isolation of GHS-R family members. In our search for endogenous ligands for the orphan receptors GHS-R and GPR38, we showed that adenosine is a partial agonist of the GHS-R and that motilin is the endogenous ligand for GPR38. We also confirmed that the endogenous ligand ghrelin is a full agonist of the GHS-R.
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Tan C, Costello P, Sanghera J, Dominguez D, Baulida J, de Herreros AG, Dedhar S. Inhibition of integrin linked kinase (ILK) suppresses beta-catenin-Lef/Tcf-dependent transcription and expression of the E-cadherin repressor, snail, in APC-/- human colon carcinoma cells. Oncogene 2001; 20:133-40. [PMID: 11244511 DOI: 10.1038/sj.onc.1204052] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Loss of functional adenomatous polyposis coli (APC) protein results in the stabilization of cytosolic beta-catenin and activation of genes that are responsive to Lef/Tcf family transcription factors. We have recently shown that an independent cell adhesion and integrin linked kinase (ILK)-dependent pathway can also activate beta-catenin/LEF mediated gene transcription and downregulate E-cadherin expression. In addition, ILK activity and expression are elevated in adenomatous polyposis and colon carcinomas. To examine the role of this pathway in the background of APC mutations we inhibited ILK activity in APC-/- human colon carcinoma cell lines. In all cases, inhibition of ILK resulted in substantial inhibition of TCF mediated gene transcription and inhibition of transcription and expression of the TCF regulated gene, cyclin D1. Inhibition of ILK resulted in decreased nuclear beta-catenin expression, and in the inhibition of phosphorylation of GSK-3 and stimulation of its activity, leading to accelerated degradation of beta-catenin. In addition, inhibition of ILK suppressed cell growth in culture as well as growth of human colon carcinoma cells in SCID mice. Strikingly, inhibition of ILK also resulted in the transcriptional stimulation of E-cadherin expression and correlated with the inhibition of gene transcription of snail, a repressor of E-cadherin gene expression. Overexpression of ILK caused a stimulation of expression of snail, but snail expression was found not to be regulated by beta-catenin/Tcf. These data demonstrate that ILK can regulate beta-catenin/TCF and snail transcription factors by distinct pathways. We propose that inhibition of ILK may be a useful strategy in the control of progression of colon as well as other carcinomas. Oncogene (2001) 20, 133 - 140.
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Freeman J, Katsilerou A, Tan C, Karnik A, Balchin J. Crit Care 2001; 1:P059. [DOI: 10.1186/cc3835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Weiss D, Carr D, Kellachan J, Tan C, Phillips M, Bresnitz E, Layton M. Clinical findings of West Nile virus infection in hospitalized patients, New York and New Jersey, 2000. Emerg Infect Dis 2001; 7:654-8. [PMID: 11589170 PMCID: PMC2631758 DOI: 10.3201/eid0704.010409] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Outbreaks of West Nile (WN) virus occurred in the New York metropolitan area in 1999 and 2000. Nineteen patients diagnosed with WN infection were hospitalized in New York and New Jersey in 2000 and were included in this review. Eleven patients had encephalitis or meningoencephalitis, and eight had meningitis alone. Ages of patients ranged from 36 to 87 years (median 63 years). Fever and neurologic and gastrointestinal symptoms predominated. Severe muscle weakness on neurologic examination was found in three patients. Age was associated with disease severity. Hospitalized cases and deaths were lower in 2000 than in 1999, although the case-fatality rate was unchanged. Clinicians in the Northeast should maintain a high level of suspicion during the summer when evaluating older patients with febrile illnesses and neurologic symptoms, especially if associated with gastrointestinal complaints or muscle weakness.
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Tan C. How a "difficult" patient opened my eyes. MEDICAL ECONOMICS 2000; 77:100, 103-4. [PMID: 11116440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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Koh D, Tan C, Ng SK, Tan BT, Leow YH, Goh CL. Screening for p-phenylenediamine (PPD) in hair-care products by thin-layer chromatography (TLC). Contact Dermatitis 2000; 43:182-3. [PMID: 10985645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Chang S, Tan C, Frankel EN, Barrett DM. Low-density lipoprotein antioxidant activity of phenolic compounds and polyphenol oxidase activity in selected clingstone peach cultivars. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2000; 48:147-51. [PMID: 10691607 DOI: 10.1021/jf9904564] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The antioxidant potential of eight clingstone peach cultivars was investigated by determining phenolic compounds and inhibition of low-density lipoprotein (LDL) oxidation. Cultivars low in polyphenol oxidase (PPO) were also selected to minimize enzymatic browning. Inhibition of LDL oxidation varied from 17.0 to 37.1% in peach flesh extract, from 15.2 to 49.8% in whole peach extract, and from 18.2 to 48.1% in peel extract. Total phenols were 432.8-768.1 mg/kg in flesh extract, 483.3-803.0 mg/kg in whole extract, and 910.9-1922.9 mg/kg in peel extract. The correlation coefficient between relative LDL antioxidant activity and concentration of total phenols was 0.76. Peel PPO activity was higher than flesh activity in most cultivars. The lowest PPO and specific activities were found in the Walgant cultivar, followed by Kakamas and 18-8-23. These three cultivars combine the desirable characteristics of strong antioxidant activity, low PPO activity, and lower susceptibility to browning reactions.
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Comai L, Song Y, Tan C, Bui T. Inhibition of RNA polymerase I transcription in differentiated myeloid leukemia cells by inactivation of selectivity factor 1. CELL GROWTH & DIFFERENTIATION : THE MOLECULAR BIOLOGY JOURNAL OF THE AMERICAN ASSOCIATION FOR CANCER RESEARCH 2000; 11:63-70. [PMID: 10672904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Transcription by RNA polymerase I (pol I) regulates the rate of ribosome biogenesis and the biosynthetic potential of the cell; therefore, it plays an important role in the control of cell growth. Differentiation of the human promyelocytic leukemic cell line U937 is accompanied by drastic decreases in pol I transcriptional activity. We have used cell-free extracts prepared from undifferentiated and differentiated U937 cells to investigate the molecular mechanisms responsible for this inhibitory process. Our analysis indicates that the activity of the TATA binding protein (TBP)/TBP-associated factor (TAF) complex selectivity factor 1 (SL1), one of the factors required for accurate and promoter-specific transcription by RNA pol I, is severely repressed in differentiated U937 cells. Moreover, the reduction in SL1 activity is not a consequence of a decrease in SL1, because there is no detectable difference in the abundance of TBP or TAFs before and after U937 cell differentiation. In conclusion, our results indicate that the selectivity factor SL1 is an important target for the regulation of pol I transcription during cell differentiation.
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Troussard AA, Tan C, Yoganathan TN, Dedhar S. Cell-extracellular matrix interactions stimulate the AP-1 transcription factor in an integrin-linked kinase- and glycogen synthase kinase 3-dependent manner. Mol Cell Biol 1999; 19:7420-7. [PMID: 10523630 PMCID: PMC84735 DOI: 10.1128/mcb.19.11.7420] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Integrin-mediated interactions of cells with components of the extracellular matrix regulate cell survival, cell proliferation, cell differentiation, and cell migration. Some of these physiological responses are regulated via activation of transcription factors such as activator protein 1 (AP-1). Integrin-linked kinase (ILK) is an ankyrin repeat containing serine-threonine protein kinase whose activity is rapidly and transiently stimulated by cell-fibronectin interactions as well as by insulin stimulation. ILK activates protein kinase B and inhibits the glycogen synthase kinase 3 (GSK-3) activity in a phosphatidylinositol-3-kinase (PI 3-kinase)-dependent manner. We now show that cell adhesion to fibronectin results in a rapid and transient stimulation of AP-1 activity. At the same time, the kinase activity of ILK is stimulated whereas that of GSK-3 is inhibited. This fibronectin-dependent activation of AP-1 activity is inhibited in a dose-dependent manner if the cells are transfected with wild-type GSK-3, and also by inhibitors of PI 3-kinase. Stable or transient overexpression of ILK results in a stimulation of AP-1 activity which is inhibited by cotransfection with wild-type GSK-3 and kinase-deficient ILK. Transient transfection of ILK in HEK-293 cells stimulates complex formation between an AP-1 consensus oligonucleotide and nuclear proteins containing c-jun. The formation of this complex is inhibited by cotransfection with active GSK-3 or kinase-deficient ILK, suggesting that ILK may regulate AP-1 activation by inhibiting GSK-3, which has previously been shown to be a negative regulator of AP-1. In the presence of serum, ILK has no effect on the phosphorylation of Ser-73 in the N-terminal transactivation domain of c-jun. These results demonstrate a novel signaling pathway for the adhesion-mediated stimulation of AP-1 transcriptional activity involving ILK and GSK-3 and the subsequent regulation of the c-jun-DNA interaction.
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Hagani AB, Rivière I, Tan C, Krause A, Sadelain M. Activation conditions determine susceptibility of murine primary T-lymphocytes to retroviral infection. J Gene Med 1999; 1:341-51. [PMID: 10738551 DOI: 10.1002/(sici)1521-2254(199909/10)1:5<341::aid-jgm58>3.0.co;2-j] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Genetically modified T-lymphocytes are potential therapeutic agents for the treatment of various disorders. Successful retroviral infection of primary murine T-lymphocytes is a prerequisite to the study of adoptive cell therapies in a small animal model. The definition of factors controlling retroviral infection of T-lymphocytes would also be useful to better understand retroviral diseases. However, retroviral-mediated gene transfer into murine primary T-cells has remained elusive. METHODS In order to define the requirements for stable and efficient gene transfer in primary murine T-lymphocytes, we investigated factors capable of affecting retroviral infection. These include activation conditions (using mitogens or monoclonal antibodies), culture conditions (including media composition and cytokine addition), timing of viral exposure, retroviral receptor selection (ecotropic, amphotropic, or vesicular stomatitis virus G (VSV-G) glycoprotein receptor), and viral titer. RESULTS We show that efficient gene transfer can be achieved in murine T-lymphocytes, provided that a number of favorable conditions are met, in particular optimized T-cell activation conditions, optimal timing of infection, adequate interleukin-2 concentration and T-cell density, and a high viral titer. On a particulate basis, we find that ecotropic particles are more effective than amphotropic or VSV-G-pseudotyped particles, and recommend the use of a specifically selected retroviral packaging cell line. CD4+ T-cells are equally or more infectible than CD8+ lymphocytes, depending on the activation conditions. The Th1 and Th2 subsets are comparably susceptible to retroviral infection, in contrast to what has been reported in some instances of human T-cell infection by human immunodeficiency virus (HIV). CONCLUSIONS We establish conditions that enable efficient retroviral-mediated gene transfer in murine primary T-lymphocytes. T-lymphocytes are not uniformly susceptible to retroviral infection depending on the mode of T-cell activation. These findings have implications for devising approaches to the study of T-cell biology, adoptive cell therapies, and the pathophysiology of retroviral diseases in mouse models.
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Shi LJ, Zhang HJ, Tang WP, Li GD, Tan C, Song L. [Cardiovascular response to high sustained +Gz stress in dogs]. HANG TIAN YI XUE YU YI XUE GONG CHENG = SPACE MEDICINE & MEDICAL ENGINEERING 1999; 12:214-6. [PMID: 11766713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Objective. To investigate features of electrocardiography (ECG) and arterial pressure in dog during and after +Gz stress. Method. Six anesthetized dogs were catheterized for the measurement of ascending aortic pressure (AP) and common iliac arterial pressure (CIAP). A lead of ECG was monitored continuously. Then, dogs were placed supine in rotatable platform on one arm of an 1.7 m radius centrifuge. The animals were exposed serially to acceleration profiles of up to +7 Gz, consisting of a slow onset to peak acceleration, 90 s peak G, and a rapid decline back to control. A recovery time of at least 20 min was allowed after each acceleration profile. Result. (1) The amplitude of P-wave was influenced by the magnitude of the acceleration (2.3 +/- 0.2 mV at rest vs. 4.5 +/- 0.5 mV at +3 Gz, 4.8 +/- 0.3 mV at +5 Gz and 5.3 +/- 0.7 mV at +7 Gz, respectively P<0.05). (2) It appeared that arterial mean pressure increased and pulse pressure decreased in CIAP during high +Gz stress. (3) AP increased greatly after +Gz stress (17.29 +/- 5.59/11.31 +/- 3.86 kPa at rest vs. 27.53 +/- 6.12/20.62 +/- 1.86 kPa 30s after +7 Gz P<0.01). Conclusion. (1) The change of the amplitude of P-wave reflected the atrial displacement which may be the reason of arrhythmia. (2) The perfusion pressure is an important physiological parameter to the cardiovascular dysfunction during high +Gz stress. (3) Greatly higher AP after +Gz stress could be a feature of vascular exhaustion.
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Papadakis V, Vlachopapadopoulou E, Van Syckle K, Ganshaw L, Kalmanti M, Tan C, Sklar C. Gonadal function in young patients successfully treated for Hodgkin disease. MEDICAL AND PEDIATRIC ONCOLOGY 1999; 32:366-72. [PMID: 10219339 DOI: 10.1002/(sici)1096-911x(199905)32:5<366::aid-mpo10>3.0.co;2-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Gonadal function in pediatric and young adult survivors of Hodgkin disease is not very well defined. This study evaluates the outcome following the Multiple Drug Protocol (MDP) and the results are compared to the published experience. PROCEDURE Ovarian and testicular function was assessed in 65 patients (36 males) with Hodgkin disease in first or second complete remission after treatment with either radiation (RT, n = 13), chemotherapy (CT, n = 9), or both (n = 43). Chemotherapy consisted of six cycles of the MDP (doxorubicin, procarbazine, prednisone, vincristine, and cyclophosphamide). Median age at diagnosis was 13.1 years (range, 2.4-22.6) and median age at evaluation was 22.6 years (range, 15.1-33.7), which was 6.7 years (range, 2.0-19.8) after the completion of all treatments. For the purpose of analysis, patients were divided into three groups: group A, patients who received only RT that did not include the pelvis (8 females, 5 males); group B, patients who received CT but no pelvic RT (15 females, 25 males); and group C, patients who received CT plus pelvic RT (6 females, 6 males). RESULTS All patients progressed spontaneously through puberty and evaluable patients were found to be sexually mature (Tanner stage IV and V). Serum follicle stimulating hormone (FSH) was increased in 0/5, 13/25, and 5/6 and testicular volume was decreased in 1/3, 4/11, and 2/3 group A, B, and C male patients, respectively. Leydig cell dysfunction was uncommon; 91% and 88% of males had normal serum concentrations of luteinizing hormone (LH) and testosterone, respectively. FSH and LH were increased in 0/8, 3/15, and 2/6 group A, B, and C female patients, respectively, at last follow-up, indicating a 17% prevalence of ovarian dysfunction. Serial data in seven females whose initial levels of FSH/LH were elevated revealed normalization in four. Six females delivered eight normal children. CONCLUSIONS The majority of males who received CT +/- RT have evidence of germ cell dysfunction, while Leydig cell function is unaffected in most. In females, although abnormal function early after the end of treatment was observed, ovarian function remained or returned to normal in most young women. Thus, in females the results of hormone testing performed early after treatment may not be predictive of their eventual reproductive potential.
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Ambrosini PJ, Wagner KD, Biederman J, Glick I, Tan C, Elia J, Hebeler JR, Rabinovich H, Lock J, Geller D. Multicenter open-label sertraline study in adolescent outpatients with major depression. J Am Acad Child Adolesc Psychiatry 1999; 38:566-72. [PMID: 10230188 DOI: 10.1097/00004583-199905000-00018] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim of this multicenter outpatient study was to assess the therapeutic benefits, response patterns, and safety of sertraline in adolescent major depressive disorder (MDD). METHOD Fifty-three adolescent outpatients with MDD were treated in an open-label, 10-week, acute-phase trial with sertraline and, if responders, for an additional 12-week continuation phase. Diagnostic and response assessments included the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS), 17-item K-SADS-derived depression severity score, Hamilton Depression Rating Scale, Beck Depression Inventory, and Clinical Global Impression Scale. RESULTS By 2 weeks, when analyzed as continuous variables, all severity scores showed significant differences from baseline. This pattern persisted through 10 weeks, with a significantly greater response occurring when treatment was extended from 6 to 10 weeks. Both clinician- and patient-rated improvement was maintained during continuation treatment. Response rates varied considerably when depression rating scales were analyzed categorically. Sertraline was generally well tolerated and did not induce manic symptoms. CONCLUSIONS In open treatment of adolescent MDD with sertraline, significant improvement occurred early on and was maintained for 22 weeks. Absolute response rates varied depending on the rating scales used, definition of response, and length of treatment. Maximal response rates were obtained by clinician-defined ratings after 10 weeks of treatment.
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Mowbray CT, Tan C. Consumer-operated drop-in centers: evaluation of operations and impact. JOURNAL OF MENTAL HEALTH ADMINISTRATION 1999; 20:8-19. [PMID: 10125387 DOI: 10.1007/bf02521399] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Research on self-help for consumers of psychiatric services has focused on the operation of voluntary groups and largely ignored service programs operated by consumers. This evaluation study focused on six consumer-operated drop-in centers, each established for at least two years. These centers served a combined total of 1,445 consumers and were funded as demonstration projects by the Michigan Department of Mental Health. Structured interviews of consumer-users of these centers indicated that the program was meeting its funding intents of serving people with serious mental illness and of creating an environment promoting social support and shared problem solving. Levels of satisfaction were uniformly high; there were few differences across centers. Issues that emerged for future policy and research considerations included funding constraints, enhancing accessibility (particularly for women and people needing frequent hospitalization), variable levels of support from catchment area community mental health agencies, and determining the long-term benefits of drop-in center participation.
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Wong JS, Yip L, Tan C, Chew P. Trabeculectomy survival with and without intra-operative 5-fluorouracil application in an Asian population. AUSTRALIAN AND NEW ZEALAND JOURNAL OF OPHTHALMOLOGY 1998; 26:283-8. [PMID: 9843255 DOI: 10.1111/j.1442-9071.1998.tb01331.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To define and compare the trabeculectomy survival with regard to intra-ocular pressure (IOP) control without further surgery or anti-glaucoma medication n an Asian population. METHODS A retrospective review of two consecutive groups of patients who had trabeculectomy surgery in a university eye department setting. The first group of patients (group A) did not receive any adjunctive 5-fluorouracil (5-FU), while the second group (group B) had intra-operative sponge application of 5-FU. Only the first trabeculectomy of patients who had bilateral trabeculectomy and the first trabeculectomy performed in patients who had repeated surgery was analysed. Combined procedures were excluded. Survival analysis was performed using the Kaplan-Meier product limit method. RESULTS Eighty-nine patients (51 in group A and 38 in group B) were studied, with a mean follow up of 37.5 and 27.0 months, respectively (P = 0.014). There were no statistical differences in age, gender, mean pretreatment IOP, pre-operative medication, proportion of patients with previous ocular surgery, or proportion of primary compared with secondary glaucoma between the two groups. The probability of trabeculectomy survival (IOP < 22 mmHg without additional medication/surgery) at 12 and 36 months was 54.3 and 36.4%, respectively, in group A and 75.8 and 65.8%, respectively, in group B. The differences in survival were significant (P = 0.006, log rank test). CONCLUSIONS Our experience with trabeculectomy survival in the Asian population showed poorer success when compared with Caucasian populations reported by other investigators. The survival of trabeculectomy surgery was improved significantly with intra-operative 5-FU. There may be justification for advocating a more liberal use of intra-operative 5-FU in such a population.
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Tan C, Sng BL, Long J, Loh LK, Liew R, Aw E. Discharge planning in a community hospital--a multidisciplinary approach. Singapore Med J 1998; 39:461-4. [PMID: 9885709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The population of Singapore is ageing rapidly. Acute hospitals in Singapore are also experiencing an acute bed shortage. However, many elderly admitted to acute hospitals require a longer period of convalescence before they are able to go home. Community hospitals are most suitable to provide such care for the elderly patient. Patients could be discharged to the community hospitals to continue rehabilitation and convalescence. In addition this would also free the beds in the acute hospitals. However, there is a risk that without adequate discharge planning, the community hospitals would in turn also reach full capacity and no longer be able to accept patients. A discharge planning programme has been set up in a community hospital to address the following needs: 1) caring for a rapidly ageing population with increasing degrees of disability; 2) the shortage of beds in the acute hospitals; (3) the provision of holistic care and care-giver education, and 4) to prevent long term institutionalisation of the elderly as much as possible.
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Delcommenne M, Tan C, Gray V, Rue L, Woodgett J, Dedhar S. Phosphoinositide-3-OH kinase-dependent regulation of glycogen synthase kinase 3 and protein kinase B/AKT by the integrin-linked kinase. Proc Natl Acad Sci U S A 1998; 95:11211-6. [PMID: 9736715 PMCID: PMC21621 DOI: 10.1073/pnas.95.19.11211] [Citation(s) in RCA: 874] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Integrin-linked kinase (ILK) is an ankyrin-repeat containing serine-threonine protein kinase capable of interacting with the cytoplasmic domains of integrin beta1, beta2, and beta3 subunits. Overexpression of ILK in epithelial cells disrupts cell-extracellular matrix as well as cell-cell interactions, suppresses suspension-induced apoptosis (also called Anoikis), and stimulates anchorage-independent cell cycle progression. In addition, ILK induces nuclear translocation of beta-catenin, where the latter associates with a T cell factor/lymphocyte enhancer-binding factor 1 (TCF/LEF-1) to form an activated transcription factor. We now demonstrate that ILK activity is rapidly, but transiently, stimulated upon attachment of cells to fibronectin, as well as by insulin, in a phosphoinositide-3-OH kinase [Pi(3)K]-dependent manner. Furthermore, phosphatidylinositol(3,4,5)trisphosphate specifically stimulates the activity of ILK in vitro, and in addition, membrane targetted constitutively active Pi(3)K activates ILK in vivo. We also demonstrate here that ILK is an upstream effector of the Pi(3)K-dependent regulation of both protein kinase B (PKB/AKT) and glycogen synthase kinase 3 (GSK-3). Specifically, ILK can directly phosphorylate GSK-3 in vitro and when stably, or transiently, overexpressed in cells can inhibit GSK-3 activity, whereas the overexpression of kinase-deficient ILK enhances GSK-3 activity. In addition, kinase-active ILK can phosphorylate PKB/AKT on serine-473, whereas kinase-deficient ILK severely inhibits endogenous phosphorylation of PKB/AKT on serine-473, demonstrating that ILK is involved in agonist stimulated, Pi(3)K-dependent, PKB/AKT activation. ILK is thus a receptor-proximal effector for the Pi(3)K-dependent, extracellular matrix and growth factor mediated, activation of PKB/AKT, and inhibition of GSK-3.
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Tan C, Cao Y, Hu P. [The experimental research of inner ear metabolism and electrical physiology of autoimmune sensorineural hearing loss]. LIN CHUANG ER BI YAN HOU KE ZA ZHI = JOURNAL OF CLINICAL OTORHINOLARYNGOLOGY 1998; 12:407-10. [PMID: 11263148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Inquire into the mechanism of inner ear pathological physiology in autoimmune sensorineural hearing loss (ASHL). With the auditory electric-physiological techniques and enzyme-histochemical method, the change of inner ear hearing function and enzyme activity were observed. These animals, which threshold of auditory nerve compound active potential (CAP) and cochlear microphonic potential(CM) heightening evidently, showed that the amplitude of endolymphatic potential(EP) (include-EP) bring down in various degrees, which was related to the change of the active of Na(+)-K(+)-ATPase and SDH in vascularis stria and endolymphatic sac. The abnormality of enzymes metabolism in inner ear tissues, which following autoimmune inflammation damage, is the pathological foundation of hearing dysfunction.
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Krause A, Guo HF, Latouche JB, Tan C, Cheung NK, Sadelain M. Antigen-dependent CD28 signaling selectively enhances survival and proliferation in genetically modified activated human primary T lymphocytes. J Exp Med 1998; 188:619-26. [PMID: 9705944 PMCID: PMC2213361 DOI: 10.1084/jem.188.4.619] [Citation(s) in RCA: 219] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/1997] [Revised: 05/14/1998] [Indexed: 11/04/2022] Open
Abstract
Most tumor cells function poorly as antigen-presenting cells in part because they do not express costimulatory molecules. To provide costimulation to T lymphocytes that recognize tumor cells, we constructed a CD28-like receptor specific for GD2, a ganglioside overexpressed on the surface of neuroblastoma, small-cell lung carcinoma, melanoma, and other human tumors. Recognition of GD2 was provided by a single-chain antibody derived from the GD2-specific monoclonal antibody 3G6. We demonstrate that the chimeric receptor 3G6-CD28 provides CD28 signaling upon specific recognition of the GD2 antigen on tumor cells. Human primary T lymphocytes retrovirally transduced with 3G6-CD28 secrete interleukin 2, survive proapoptotic culture conditions, and selectively undergo clonal expansion in the presence of an antiidiotypic antibody specific for 3G6-CD28. Polyclonal CD8(+) lymphocytes expressing 3G6-CD28 are selectively expanded when cultured with cells expressing allogeneic major histocompatibility complex class I together with GD2. Primary T cells given such an antigen-dependent survival advantage should be very useful to augment immune responses against tumor cells.
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Tan C, Cao Y, Liu H. [Cochlear and retrocochlear deafness induced by immunity with different inner ear tissue antigens]. LIN CHUANG ER BI YAN HOU KE ZA ZHI = JOURNAL OF CLINICAL OTORHINOLARYNGOLOGY 1998; 12:370-3. [PMID: 11263162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
OBJECTIVES To inquire into whether the different inner ear tissue antigens could cause different kind of hearing loss, and to find out the disorder positions of auditory system. METHODS The basilar membrane (BM), spiral ligament (SL), and spiral ganglion (SG) of guinea pigs were removed for making antigens, respectively. Then, we used these antigens to immune guinea pigs. The special humour and cellular immune reaction, hearing function, and inner ear histopathological changes were observed. RESULTS In BM-antigen and SL-antigen immune group, the various degrees of cochlear microphonic potential disturbance, recruitment, and immune pathological inflammation in cochlear duct and stria vascularis were found. In SG-antigen immune group, auditory nerve compound action potential changes were prominent, and the inner ear pathological damage mainly existed in cochlear axis vessels or surround areas, and SG. CONCLUSIONS It was confirmed that the inner ear antigens come from different part of auditory system, which could cause cochlear or retrocochlear autoimmune disease.
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Deardorff MA, Tan C, Conrad LJ, Klein PS. Frizzled-8 is expressed in the Spemann organizer and plays a role in early morphogenesis. Development 1998; 125:2687-700. [PMID: 9636083 DOI: 10.1242/dev.125.14.2687] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Wnts are secreted signaling molecules implicated in a large number of developmental processes. Frizzled proteins have been identified as likely receptors for Wnt ligands in vertebrates and invertebrates, but a functional role for vertebrate frizzleds has not yet been defined. To assess the endogenous role of frizzled proteins during vertebrate development, we have identified and characterized a Xenopus frizzled gene (xfz8). It is highly expressed in the deep cells of the Spemann organizer prior to dorsal lip formation and in the early involuting marginal zone. Ectopic expression of xfz8 in ventral cells leads to complete secondary axis formation and can synergize with Xwnt-8 while an inhibitory form of xfz8 (Nxfz8) blocks axis duplication by Xwnt-8, consistent with a role for xfz8 in Wnt signal transduction. Expression of Nxfz8 in dorsal cells has profound effects on morphogenesis during gastrulation and neurulation that result in dramatic shortening of the anterior-posterior axis. Our results suggest a role for xfz8 in morphogenesis during the gastrula stage of embryogenesis.
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Li D, Ong CN, Ng V, Tan C. Effect of nickel chloride on mouse T-lymphocyte subsets. VETERINARY AND HUMAN TOXICOLOGY 1998; 40:129-31. [PMID: 9610487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The study was carried out to observe the effect of nickel chloride (NiCl2) on T-lymphocyte subsets, CD4, CD8 and CD4/CD8 ratios in vivo. BALB/C mice were injected i.p. with NiCl2 every other day for 2 w. The NiCl2 doses were 1, 3, 6, 9 or 12 mg/kg. Lymphocytes were obtained from mouse spleen and cultured in the presence of monoclonal antibody FITC conjugated, anti-CD4 or anti-CD8. Samples were determined with a flow cytometer. A suppressive effect on CD4-positive cells was found in the 6 mg/kg group, but this subset was restored to the control level in the 9 and 12 mg/kg groups, suggesting that there was an "immune tolerance" effect. No significant changes were found in CD8-positive cells and CD4/CD8 ratios. The results suggested the NiCl2 had a deleterious effect on mouse T-lymphocytes in short-term in vivo exposure, but the effects may depend on the dose and cell subset.
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Tan C, Cao Y, Liu H. [The clinical study of immune factors relative to Menière's disease]. LIN CHUANG ER BI YAN HOU KE ZA ZHI = JOURNAL OF CLINICAL OTORHINOLARYNGOLOGY 1998; 12:208-10. [PMID: 11189157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
It was investigated that the clinical unspecialized immunological factors and special immune reaction against to inner ear antigens relate with the cause of Meniere's disease. Every of the relative immune tests and special humoral and cellular immune reaction tests were proceeded in the breaking out and intermittent period of Meniere's disease patients, and the normal controls. The levels of IgG and C3 in serum and unspecialized lymphocyte blastogenesis increased, and positive of circular immune compound and antibody against cellular nucleus, and special humoral and cellular immune reaction against inner ear antigens during the breaking out period of the patients. The element of inner ear autoimmune could play an important role in the pathogenical mechanism of some patients with Meniere's disease.
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Wolkenstein P, Tan C, Lecoeur S, Wechsler J, Garcia-Martin N, Charue D, Bagot M, Beaune P. Covalent binding of carbamazepine reactive metabolites to P450 isoforms present in the skin. Chem Biol Interact 1998; 113:39-50. [PMID: 9630846 DOI: 10.1016/s0009-2797(98)00021-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Carbamazepine is an anticonvulsant associated with a high risk for severe cutaneous reactions. Upon metabolism by cytochrome P450, carbamazepine may produce reactive metabolites. We evaluated in vitro the covalent binding of carbamazepine reactive metabolites on human P450s and then the presence of these P450s in human epidermis. Carbamazepine reactive metabolites covalent binding to human liver microsomes involved P450 subfamilies 1A, 2C and 3A. Specific covalent binding to yeasts expressing different P450s showed that carbamazepine reactive metabolites bound specifically to P450 1A2 and 3A4. We confirmed the constitutive presence of P450 3A in human epidermis and after induction with coaltar of P450 1A. Consequently, the production in epidermis of carbamazepine reactive metabolites is theoretically possible with formation of P450 adduct metabolites.
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