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Tang HY, Du WD, Cui Y, Fan X, Quan C, Fang QY, Zhou FS, Yao FM, Wang JF, Yang S, Zhang X. One novel and two recurrent mutations in the keratin 5 gene identified in Chinese patients with epidermolysis bullosa simplex. Clin Exp Dermatol 2010; 34:e957-61. [PMID: 20055872 DOI: 10.1111/j.1365-2230.2009.03703.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Epidermolysis bullosa simplex (EBS) is a group of inherited skin diseases, characterized by the formation of intraepidermal blisters. We performed genetic analysis of the keratin 5 (KRT5) gene in two Chinese pedigrees. One novel missense mutation was identified in a patient with sporadic EBS (general, non-Dowling-Meara). Sequence analysis showed a heterozygous T > A transition at nucleotide 1730 of KRT5, changing phenylalanine (Phe) to tyrosine (Tyr) at position 577 of the keratin 5 (K5). In addition, two recurrent mutations c.1649delG (p.Gly550AlafsX77) and c.508G > (p.Glu170Lys) in KRT5 were identified in Chinese patients with mottled pigmentation EBS and localized EBS, respectively. None of the mutations were found in any unaffected family members or in an additional 100 unrelated control samples. These results suggest that these mutations are pathogenic and might be one of the potential causes of EBS in these Chinese patients.
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Lin S, Jin Y, Fu L, Quan C, Yang YS. Microbial community variation and functions to excess sludge reduction in a novel gravel contact oxidation reactor. JOURNAL OF HAZARDOUS MATERIALS 2009; 165:1083-1090. [PMID: 19070427 DOI: 10.1016/j.jhazmat.2008.10.106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 10/22/2008] [Accepted: 10/23/2008] [Indexed: 05/27/2023]
Abstract
Excess biomass produced within the degradation processes of organic pollutants is creating environmental challenges. The gravel contact oxidation reactor (GCOR) filled with crushed stone globular aggregates as carriers, has been demonstrated capable of reducing the excess sludge effectively in some pilot and small-scale engineering studies. In order to evaluate the variation and structure of the microbial community and their functions to excess sludge reduction in GCOR, a conventional activated sludge reactor (ASR) was studied as a comparison. The 16S rDNA library of the universal bacteria was constructed, Shannon's diversity index (H) and Species evenness (E) were calculated with distance-based operational taxonomic unit and richness (DOTUR) for microbial diversity. Real-time quantity PCR and optical microscope were used for absolute bacterial DNA concentration and eukarya identification, respectively. Meanwhile, the suspended solid index in GCOR and ASR was detected for assessing the excess sludge production. The results indicated that the most abundant bacteria in GCOR were those related to the beta-Proteobacteria group, then gamma-Proteobacteria and to Cytophaga-Flexibacter-Bacteriode (CFB). In the ASR samples major bacteria were in the closest match with gamma-Proteobacteria, then beta-Proteobacteria and CFB. Shannon's index (H) was higher (3.41) for diversity of bacteria extracted from the carrier samples in GCOR than that (2.71) from the sludge sample in ASR. Species evenness (E) for the isolates from GCOR and ASR samples was 0.97 and 0.96, respectively. Comparison of the universal bacteria population in GCOR and ASR shows that the total bacterial DNA concentration on the GCOR carriers were 8.98 x 10(5) microg/ microl, twice that in ASR of 4.67 x 10(5) microg/ microl under normal operation of two reactors. But the MLSS in GCOR was only 4.5mg/L, 25 times less than that in ASR of 115.4 mg/L. The most representative eukarya were protozoa both in GCOR (15 no. per 20 ml) and in ASR (15 no. per 20 ml); the next abundant group was attachment plants 10 no. per 20 ml in GCOR and 4 no. per 20 ml in ASR, respectively. Rotifers and copepoda belonging to metazoan were only present in GCOR (8 no. per 20 ml for both rotifers and copepoda). The microbial diversity and population difference both in the GCOR carriers and ASR sludge indicated that the diverse microbes, a large amount of biomass forming longer microbial food chains attached on the carriers may be the main functions for the excess sludge reduction in GCOR.
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Lv YM, Yang S, Zhang Z, Cui Y, Quan C, Zhou FS, Fang QY, Du WH, Zhang FR, Chang JM, Tao XP, Zhang AL, Kang RH, Du WD, Zhang XJ. Novel and recurrent keratin 6A (KRT6A) mutations in Chinese patients with pachyonychia congenita type 1. Br J Dermatol 2009; 160:1327-9. [PMID: 19416275 DOI: 10.1111/j.1365-2133.2009.09062.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Zhang H, Quan C, Sun LD, Lv HL, Gao M, Zhou FS, Xiao FL, Fang QY, Shen YJ, Zhou L, Yang S, Zhang XJ. A novel frameshift mutation of the EDA1 gene in a Chinese Han family with X-linked hypohidrotic ectodermal dysplasia. Clin Exp Dermatol 2008; 34:74-6. [PMID: 18702659 DOI: 10.1111/j.1365-2230.2008.02844.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hypohidrotic ectodermal dysplasia (HED) is a rare skin disease characterized by hypotrichosis, hypodontia and hypohidrosis. HED can be autosomal dominant, autosomal recessive or X-linked. However, X-linked HED (XLHED; OMIM 305100) is the most common form. Mutations within the EDA1 gene, which encodes ectodysplasin-A, are responsible for XLHED. In this study, we investigated the EDA1 gene in a Chinese Han family with XLHED, and found a novel 1-bp deletion mutation (c.952delG) in exon 9 of the EDA1 gene, which results in a frameshift and premature termination codon. This result suggests that the c.952delG mutation of the EDA1 gene is likely to be the disease-causing mutation for XLHED in this family. Our study adds new data to the worldwide knowledge of the molecular basis of XLHED.
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Quan C, Liang YH, Zhang ZZ, Lv HL, Ren YQ, Lu WS, Gao M, Wang PG, Yang S, Zhang XJ. Two novel frame-shift mutations of ATP2A2 gene in Chinese patients with Darier's disease. J Eur Acad Dermatol Venereol 2008; 22:745-6. [DOI: 10.1111/j.1468-3083.2007.02446.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lv HL, Huang YJ, Zhou D, Du YF, Zhao XY, Liang YH, Quan C, Zhang H, Zhou FS, Gao M, Zhou L, Yang S, Zhang XJ. A novel missense mutation of CYLD gene in a Chinese family with multiple familial trichoepithelioma. J Dermatol Sci 2008; 50:143-6. [PMID: 18242958 DOI: 10.1016/j.jdermsci.2007.11.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Revised: 11/19/2007] [Accepted: 11/23/2007] [Indexed: 12/22/2022]
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Zhang ZZ, Liang YH, Quan C, Gao M, Xiao FL, Yang S, Zhang XJ, Zhou FS, Li W, Fang QY, Shen YJ, Du WH, Mu YZ, Sui WC, Zhou L. Three novel ATP2C1 mutations in Chinese patients with Hailey-Hailey disease. Br J Dermatol 2008; 158:831-3. [PMID: 18205868 DOI: 10.1111/j.1365-2133.2007.08400.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Xu SX, Wang HL, Fan X, Sun LD, Yang S, Wang PG, Xiao FL, Gao M, Cui Y, Ren YQ, Du WH, Quan C, Zhang XJ. The familial risk of acne vulgaris in Chinese Hans ? a case-control study. J Eur Acad Dermatol Venereol 2007; 21:602-5. [PMID: 17447973 DOI: 10.1111/j.1468-3083.2006.02022.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Acne is a chronic inflammatory disease of the pilosebaceous follicles. Recent studies bring us increasing evidences that hereditary factors play an important but indirect role in acne. OBJECTIVE To investigate the possible role of genetic factors in the pathogenesis of acne vulgaris in Chinese Han ethnic group. PATIENTS AND METHODS Volunteers of 975 acne cases and 580 controls were included, contributing 3009 and 1825 first-degree relatives, respectively. One thousand and eighty-five first-degree relatives of acne cases were affected with facial acne. This compared with 223 first-degree relatives of non-acne controls. The odds ratio was used to estimate the relative risk for acne vulgaris associated with having an affected first-degree relative. RESULTS The risk of acne vulgaris occurring in a relative of a patient with acne vulgaris was significantly greater than for the relative of an unaffected individual (odds ratio 4.05, 95% confidence interval (CI): 3.45-4.76, P<0.001). CONCLUSION Our study suggests that familial factors are important in determining individual susceptibility to acne vulgaris.
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Wu HX, Tang ZG, Hu H, Quan C, Song HH, Li SY. Predictions for Start-Up Processes of Reactive Distillation Column via Artificial Neural Network. Chem Eng Technol 2006. [DOI: 10.1002/ceat.200500345] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Quan C, Zhang L, Wang Y, Ohta Y. Production of phytase in a low phosphate medium by a novel yeast Candida krusei. J Biosci Bioeng 2005; 92:154-60. [PMID: 16233076 DOI: 10.1263/jbb.92.154] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2001] [Accepted: 05/23/2001] [Indexed: 11/17/2022]
Abstract
A yeast strain producing high levels of phytase was isolated from soil and identified as Candida krusei. The phytase was located on the yeast cell wall and was a glucanase-extractable protein. The phytase production was controlled by the phosphate concentration in the medium used. The maximum production of phytase occurred in a medium containing 0.5 mg of phosphorus per 100 ml, and most of the cells were ellipsoid-shaped and did not exhibit budding. Increasing the concentration of phosphorus in the medium to more than 5 mg of phosphorus per 100 ml caused inhibition of phytase production and 90% of the cells exhibited budding. On the other hand, transferring cells grown in the high-phosphate medium into a phosphate-free one derepressed the phytase production. For example, transferring cells grown in 2 mg of phosphorus per 100 ml into the phosphate-free medium, enhanced the total phytase activity up to 5.5-fold that in the medium containing 0.5 mg of phosphorus per 100 ml. The phytase showed two optimum pHs of 2.5 and 5.5, an optimum temperature of 40 degrees C and the K(m) value for Na-phytate was 0.03 mM. Using in vitro experiments that simulated the conditions of the digestive tract, 50-80% phosphorus was liberated from different plant samples (wheat bran, rice bran and feeds) by the strain.
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Talley NJ, Quan C, Jones MP, Horowitz M. Association of upper and lower gastrointestinal tract symptoms with body mass index in an Australian cohort. Neurogastroenterol Motil 2004; 16:413-9. [PMID: 15305996 DOI: 10.1111/j.1365-2982.2004.00530.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Food modulates gastrointestinal (GI) function and GI symptoms could alter food intake, but it is not established whether or not obese people experience more or less GI symptoms. We aimed at evaluating the association between body mass index (BMI) and specific GI symptoms in the community. Population-based random samples from Sydney, Australia (n = 777) completed a validated questionnaire. The association of each GI symptom with BMI (kg m(-2)) categories was assessed using logistic regression analysis adjusting for potential confounders. The prevalence of obesity (BMI > or =30 kg m(-2)) was 22%. There were univariate associations (adjusting for age, sex, education level, alcohol and smoking) between increased BMI category and heartburn (OR = 1.9, 95% CI 1.4, 2.5), acid regurgitation (OR = 2.1, 95% CI 1.4, 2.9), increased bloating (OR = 1.3, 95%CI 1.1, 1.6), increased stool frequency (OR = 1.4, 95% CI 1.1, 1.7), loose and watery stools (OR = 1.5, 95% CI 1.1, 2.0) and upper abdominal pain (OR = 1.3, 95% CI 1.03, 1.6). Early satiety was associated with a lower BMI category but this was not significant after adjustment (OR = 0.8, 95% CI 0.6, 1.1). Lower abdominal pain, postprandial fullness, nausea and vomiting were not associated with BMI category. In a regression model adjusting for sex, education, smoking, alcohol and all GI symptoms, older age, less early satiety and increased stool frequency and heartburn were all independently associated with increasing BMI (all P < 0.01). Heartburn and diarrhoea were associated with increased BMI, while early satiety was associated with a lower BMI in this population.
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Yap AUJ, Tan ACS, Quan C. Non-destructive characterization of resin-based filling materials using Electronic Speckle Pattern Interferometry. Dent Mater 2004; 20:377-82. [PMID: 15019453 DOI: 10.1016/j.dental.2003.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2002] [Revised: 05/31/2003] [Accepted: 06/10/2003] [Indexed: 10/27/2022]
Abstract
OBJECTIVES The aim of this study was to develop a non-destructive test for characterizing the modulus of resin-based filling materials. METHODS Five different visible-light-cured composites (Filtek A110 [AO], Z100 [ZO], Filtek Z250 [ZT], F2000 [FT] and Filtek Flow [FF]; 3M-ESPE) were selected for this study. An ESPI (Electronic Speckle Pattern Interferometry) apparatus involving cantilever beam specimens (28 mm long, 8 mm wide and 2 mm thick) was developed for determining modulus. Out-of-plane displacement upon force application was measured using two focus region lengths (22 mm [EI1]; 11 mm [EI2]) and modulus (n = 7) was subsequently computed based on cantilever beam equations. Data was compared to those obtained from three-point-bend flexural testing (n = 7) based on ISO4049:2000 specifications [ISO]. Specimens were stored in distilled water at 37 degrees C for 1 week prior to evaluation for all tests. Results were analyzed using ANOVA/Scheffe's post-hoc tests (p < 0.05) and Pearson's correlation (p < 0.01). RESULTS Modulus ranged from 5.53 to 13.99, 5.78 to 14.24 and 4.26 to 11.30 GPa for EI1, EI2 and ISO, respectively. For all three tests, the modulus of ZO and FT was significantly greater than ZT, which in turn was significantly greater than AO and FF. Correlation of EI1 and EI2 to ISO was significant, positive and very strong (r = 0.94 for EI1 and EI2). SIGNIFICANCE ESPI may be a viable method of characterizing the modulus of resin-based filling materials. As it is a non-destructive test, time-dependent effects of composites can be determined using the same specimens leading to substantial time and material savings.
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Quan C, Talley NJ, Cross S, Jones M, Hammer J, Giles N, Horowitz M. Development and validation of the Diabetes Bowel Symptom Questionnaire. Aliment Pharmacol Ther 2003; 17:1179-87. [PMID: 12752355 DOI: 10.1046/j.1365-2036.2003.01553.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Although gastrointestinal symptoms occur frequently, there is no validated measure of gastrointestinal symptoms in patients with diabetes mellitus. AIM To develop the Diabetes Bowel Symptom Questionnaire. METHODS A questionnaire derived from previously validated symptom measures was compiled to assess all relevant gastrointestinal and diabetes items. Face and content validity were ascertained by expert review. One hundred and sixty-eight patients with diabetes mellitus completed the instrument, and reliability was evaluated by a test-re-test procedure 1 week later. Concurrent validity was evaluated by an independent physician interview (n = 33). Measures of glycaemic control (glycated haemoglobin and plasma glucose) were compared with self-reported glycaemic control on a five-point Likert scale in diabetic out-patients (n = 166). RESULTS The questionnaire had adequate face and content validity. There was good to excellent test-re-test reliability for the gastrointestinal and diabetes items (median kappa: 0.63 and 0.79, respectively); concurrent validity was good to excellent (median kappa: 0.47 and 0.65, respectively), except for the items assessing the severity of gastrointestinal symptoms. Both glycated haemoglobin (P < 0.0001) and plasma glucose (P = 0.005) correlated significantly with self-reported glycaemic control. CONCLUSION The Diabetes Bowel Symptom Questionnaire appears to be a useful measure of gastrointestinal symptoms and glycaemic control in diabetes mellitus, and should have applicability in epidemiological and clinical studies.
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Abstract
Although up to 50% of patients diagnosed with nonulcer dyspepsia (NUD) have Helicobacter pylori infection and underlying chronic gastritis, it remains controversial whether any causal relationship exists. The results of worldwide epidemiological studies have been unconvincing. No clear-cut link has been documented between H. pylori and any specific symptom profile or pathophysiological mechanism in NUD. In the randomized controlled trials, methodological weaknesses may explain in part the conflicting results, but even in the well-conducted trials controversy persists. Although meta-analyses have attempted to resolve the issue, inherent methodological difficulties with meta-analysis remain a problem. Moreover, even the methodologically sound meta-analyses have reported conflicting results. In addition, predictors of treatment response remain obscure, and there continue to be theoretical concerns about the treatment of H. pylori infection in all patients with NUD. Hence, the management of these patients is challenging, but eradication of H. pylori infection may be beneficial in a small subgroup of cases with NUD that cannot be identified before treatment.
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Quan C, Decroix N, Bouvet JP. [Properties of mucosal antibodies]. JOURNAL DE LA SOCIETE DE BIOLOGIE 2002; 195:119-24. [PMID: 11723823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Mucosal antibodies consist of a variety of molecules, including secretory IgA and local IgG, involved in the first immune barrier of defence against pathogens. They account for the majority of daily synthesized immunoglobulins in the body and mostly depend on the secretory immune system which is independent from its systemic counterpart. Acting by immune exclusion and immune elimination, these immunoglobulins correspond to preimmune poly-reactive natural antibodies and to antigen-induced antibodies. Recent progress in this field have suggested new approaches of mucosal vaccines preventing the entry of pathogens in the body.
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Long SA, Quan C, Van de Water J, Nantz MH, Kurth MJ, Barsky D, Colvin ME, Lam KS, Coppel RL, Ansari A, Gershwin ME. Immunoreactivity of organic mimeotopes of the E2 component of pyruvate dehydrogenase: connecting xenobiotics with primary biliary cirrhosis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:2956-63. [PMID: 11509645 DOI: 10.4049/jimmunol.167.5.2956] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In primary biliary cirrhosis (PBC), the major autoepitope recognized by both T and B cells is the inner lipoyl domain of the E2 component of pyruvate dehydrogenase. To address the hypothesis that PBC is induced by xenobiotic exposure, we took advantage of ab initio quantum chemistry and synthesized the inner lipoyl domain of E2 component of pyruvate dehydrogenase, replacing the lipoic acid moiety with synthetic structures designed to mimic a xenobiotically modified lipoyl hapten, and we quantitated the reactivity of these structures with sera from PBC patients. Interestingly, antimitochondrial Abs from all seropositive patients with PBC, but no controls, reacted against 3 of the 18 organic modified autoepitopes significantly better than to the native domain. By structural analysis, the features that correlated with autoantibody binding included synthetic domain peptides with a halide or methyl halide in the meta or para position containing no strong hydrogen bond accepting groups on the phenyl ring of the lysine substituents, and synthetic domain peptides with a relatively low rotation barrier about the linkage bond. Many chemicals including pharmaceuticals and household detergents have the potential to form such halogenated derivatives as metabolites. These data reflect the first time that an organic compound has been shown to serve as a mimeotope for an autoantigen and further provide evidence for a potential mechanism by which environmental organic compounds may cause PBC.
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Dennis MS, Roberge M, Quan C, Lazarus RA. Selection and characterization of a new class of peptide exosite inhibitors of coagulation factor VIIa. Biochemistry 2001; 40:9513-21. [PMID: 11583150 DOI: 10.1021/bi010591l] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new series of peptide inhibitors of human Factor VIIa (FVIIa) has been identified and affinity matured from naive and partially randomized peptide phage libraries selected against the immobilized tissue factor x Factor VIIa (TF x FVIIa) complex. These "A-series" peptides contain a single disulfide bond and a 13-residue minimal core required for maximal affinity. They are exemplified by peptide A-183 (EEWEVLCWTWETCER), which binds at a newly identified exosite on the FVIIa protease domain, described in the accompanying report [Roberge, M., Santell, L., Dennis, M. S., Eigenbrot, C., Dwyer, M. A., and Lazarus, R. A. (2001) Biochemistry 40, 9522-9531]. A-183 was obtained from a trypsin digest of A-100-Z, a recombinant protein comprising A-183 and the Z domain of protein A. Surprisingly, A-183 was a very potent inhibitor of TF x FVIIa, inhibiting activation of Factor X (FX) and Factor IX and amidolytic activity of Chromozym t-PA with IC50 values of 1.6 +/- 1.2, 3.5 +/- 0.3, and 8.5 +/- 3.5 nM, respectively. Kinetic analysis revealed that A-183 was a partial (hyperbolic) mixed-type inhibitor of FX activation having a Ki of 200 pM as well as a partial competitive inhibitor of amidolytic activity. The A-series peptides were also specific and potent inhibitors of TF-dependent clotting as measured in a prothrombin time (PT) clotting assay and had no effect on the TF-independent activated partial thromboplastin time. At saturating concentrations of peptide, the maximal extent by which A-183 and A-100-Z inhibited the rate of FX activation was 78 +/- 3 and 89 +/- 6%, respectively. The degree of inhibition of the rate of FX activation correlated with a maximum fold prolongation in the PT assay of 1.8-fold for A- 183 and 3.3-fold for A-100-Z. The A-series peptides represent a new class of peptide exosite inhibitors that are capable of attenuating, rather than completely inhibiting, the activity of TF x FVIIa, potentially leading to anticoagulants with an increased therapeutic window.
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Skelton NJ, Chen YM, Dubree N, Quan C, Jackson DY, Cochran A, Zobel K, Deshayes K, Baca M, Pisabarro MT, Lowman HB. Structure-function analysis of a phage display-derived peptide that binds to insulin-like growth factor binding protein 1. Biochemistry 2001; 40:8487-98. [PMID: 11456486 DOI: 10.1021/bi0103866] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Highly structured, peptide antagonists of the interaction between insulin-like growth factor 1 (IGF-I) and IGF binding protein 1 (IGFBP-1) have recently been discovered by phage display of naïve peptide libraries [Lowman, H. B., et al. (1998) Biochemistry 37, 8870--8878]. We now report a detailed analysis of the features of this turn-helix peptide motif that are necessary for IGFBP-1 binding and structural integrity. Further rounds of phage randomization indicate the importance of residues contributing to a hydrophobic patch on one face of the helix. Alanine-scanning substitutions confirm that the hydrophobic residues are necessary for binding. However, structural analysis by NMR spectroscopy indicates that some of these analogues are less well folded. Structured, high-affinity analogues that lack the disulfide bond were prepared by introducing a covalent constraint between side chains at positions i and i + 7 or i + 8 within the helix. Analogues based on this scaffold demonstrate that a helical conformation is present in the bound state, and that hydrophobic side chains in this helix, and residues immediately preceding it, interact with IGFBP-1. By comparison of alanine scanning data for IGF-I and the turn-helix peptide, we propose a model for common surface features of these molecules that recognize IGFBP-1.
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Chico TJ, Chamberlain J, Gunn J, Arnold N, Bullens SL, Gadek TR, Francis SE, Bunting S, Horton M, Shepherd L, Lipari MT, Quan C, Knolle J, Stilz HU, Peyman A, Crossman DC. Effect of selective or combined inhibition of integrins alpha(IIb)beta(3) and alpha(v)beta(3) on thrombosis and neointima after oversized porcine coronary angioplasty. Circulation 2001; 103:1135-41. [PMID: 11222478 DOI: 10.1161/01.cir.103.8.1135] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Thrombosis and neointima formation limit the efficacy of coronary angioplasty (PTCA). Clinical trials have implicated the adhesion molecules integrin alpha(IIb)beta(3) and integrin alpha(v)beta(3) in these processes. The roles of these molecules in vascular smooth muscle cell adhesion, platelet aggregation, and the thrombotic and neointimal response to oversize porcine PTCA was investigated by use of a selective alpha(IIb)beta(3) antagonist (lamifiban), a selective alpha(v)beta(3) antagonist (VO514), and a combined alpha(IIb)beta(3)/alpha(v)beta(3) antagonist (G3580). METHODS AND RESULTS In vitro, both alpha(v)beta(3) inhibitors caused dose-dependent inhibition of porcine vascular smooth muscle cell adhesion to vitronectin but not to collagen type IV, fibronectin, or laminin, whereas selective alpha(IIb)beta(3) inhibition had no effect. Intravenous infusions of either alpha(IIb)beta(3) inhibitor in swine profoundly inhibited ex vivo platelet aggregation to ADP, whereas selective alpha(v)beta(3) inhibition had no effect. In a porcine PTCA model, intravenous infusions of the integrin antagonists were administered for 14 days after oversized balloon angioplasty injury. After PTCA, there was regional upregulation of integrin alpha(v)beta(3) in the developing neointima, as assessed by immunohistochemistry. Six hours after PTCA, obstruction of lumen by thrombus was reduced significantly by alpha(IIb)beta(3) inhibition compared with either control or alpha(v)beta(3) inhibition (mean control, 18.7%; VO514, 18.5%; lamifiban, 6.4%; G3580, 7.9%). Twenty-eight days after PTCA, there was a significant reduction of neointima with inhibitors of either integrin (mean intima/media ratio: control, 3.08; VO514, 1.33; lamifiban, 0.97; G3580, 1.32). CONCLUSIONS We conclude that both integrin alpha(IIb)beta(3) and integrin alpha(v)beta(3) participate in neointima development after experimental angioplasty.
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Quan C, Khoe G, Bagster D. Adsorption of sodium lauryl sulfate onto arsenic-bearing ferrihydrite. WATER RESEARCH 2001; 35:478-484. [PMID: 11229002 DOI: 10.1016/s0043-1354(00)00271-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ferrihydrite is an excellent adsorbent for binding trace toxic contaminants such as arsenic, and precipitate flotation of the arsenic-bearing ferrihydrite has been studied. Anionic surfactants such as sodium lauryl sulfate (SLS) and sodium oleate (NaOL) are suitable collectors for the flotation. The adsorption of SLS both alone and after the subsequent addition of NaOL on these precipitates at pH 4-5 was measured. It has been shown that the synergistic effect of the two surfactants on flotation is dependent on their addition order. The presence of NaOL before SLS in the conditioning stage can prevent the adsorption of SLS because of the electrostatic shielding of adsorption sites on the precipitates. The post addition of NaOL to the SLS-bearing precipitates can promote the flocculation of the precipitates and enhance entrainment of SLS for better flotation. The SLS adsorption data fit better with the modified Frumkin isotherm than the Langmuir isotherm. Thermodynamic parameters (-delta Gads0,delta Hads0, and delta Sads0) have been derived from the analysis of the adsorption isotherms. The results suggest that the adsorption of SLS on AFH is physical and exothermic.
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Nusrat A, Chen JA, Foley CS, Liang TW, Tom J, Cromwell M, Quan C, Mrsny RJ. The coiled-coil domain of occludin can act to organize structural and functional elements of the epithelial tight junction. J Biol Chem 2000; 275:29816-22. [PMID: 10887180 DOI: 10.1074/jbc.m002450200] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Occludin is an integral membrane protein that has been suggested to play a role in the organization and dynamic function of the epithelial tight junction (TJ). A number of other proteins have also been described to localize to the TJ. We have used a novel bait peptide method to investigate potential protein-protein interactions of the putative coiled-coil domain of occludin with some of these other TJ proteins. A 27-amino acid peptide of the human occludin sequence was synthesized, biotinylated at the N terminus, and modified to contain a photoactive moiety at either its hydrophobic or hydrophilic surface. These bait peptides were alpha-helical in solution, characteristic of coiled-coil structures. Photoactivation studies in the presence and absence of control peptides were used to assess the potential interactions in polarized sheets of a human intestinal cell line T84. Although a large number of proteins associated with the TJ or that are known to be involved in regulatory events of epithelial cells failed to be specifically labeled, occludin itself, ZO-1, protein kinase C-zeta, c-Yes, the regulatory subunit of phosphatidylinositol 3-kinase, and the gap junction component connexin 26 were specifically labeled. Our data demonstrate the potential of one specific domain of occludin, contained within 27 amino acids, to coordinate the binding of proteins that have been previously suggested to modulate TJ structure and function.
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Fuh G, Pisabarro MT, Li Y, Quan C, Lasky LA, Sidhu SS. Analysis of PDZ domain-ligand interactions using carboxyl-terminal phage display. J Biol Chem 2000; 275:21486-91. [PMID: 10887205 DOI: 10.1074/jbc.275.28.21486] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PDZ domains mediate protein-protein interactions at specialized subcellular sites, such as epithelial cell tight junctions and neuronal post-synaptic densities. Because most PDZ domains bind extreme carboxyl-terminal sequences, the phage display method has not been amenable to the study of PDZ domain binding specificities. For the first time, we demonstrate the functional display of a peptide library fused to the carboxyl terminus of the M13 major coat protein. We used this library to analyze carboxyl-terminal peptide recognition by two PDZ domains. For each PDZ domain, the library provided specific ligands with sub-micromolar binding affinities. Synthetic peptides and homology modeling were used to dissect and rationalize the binding interactions. Our results establish carboxyl-terminal phage display as a powerful new method for mapping PDZ domain binding specificity.
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Quan C, Skelton NJ, Clark K, Jackson DY, Renz ME, Chiu HH, Keating SM, Beresini MH, Fong S, Artis DR. Transfer of a protein binding epitope to a minimal designed peptide. Biopolymers 2000; 47:265-75. [PMID: 10036968 DOI: 10.1002/(sici)1097-0282(1998)47:4<265::aid-bip2>3.0.co;2-k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Results from protein mutagenesis and x-ray crystallographic studies of the multidomain protein Vascular Cell Adhesion Molecule (VCAM) were used to design cyclic octapeptides that retain the critical structural and binding elements of the epitope of VCAM in the interaction with the integrin alpha 4 beta 1 (VLA-4). Changes in the activities of peptide analogues correlated with the relative activities of protein mutants of VCAM, and predicted the properties of two new mutants that bound alpha 4 beta 1 with improved affinity vs wild type protein. The nmr structures of two peptides revealed a high degree of similarity to the structure of the VCAM binding epitope. These results demonstrate that a compact binding epitope identified via protein structure-function studies may be transferred to a synthetically accessible small peptide with the key structure-activity relationships intact.
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Shang HM, Quan C, Tay CJ, Hung YY. Generation of carrier fringes in holography and shearography. APPLIED OPTICS 2000; 39:2638-2645. [PMID: 18345182 DOI: 10.1364/ao.39.002638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Double-exposure holography and double-exposure shearography are often used together with the carrier fringe technique, which requires additional shifting of the light source in a prescribed manner between exposures. In the holographic carrier fringe technique, difficulty in prescribing a suitable movement of the light source may be alleviated through visualization of the moiré fringes that are reconstructed by slight displacement of two overlaid families of ellipsoids in a holodiagram. Because shearography is the first differential of holography, it is often impractical to perform two successive optical differentiations on the ellipsoids to visualize the shearographic carrier fringes. A simple method of discerning holographic and shearographic carrier fringes is described. The method is based on the hyperboloids in a holodiagram that represent Young's (interference) fringes produced by the interference of two point sources. The hyperboloids are analogous to holographic carrier fringes, whereas the moiré patterns reconstructed from two overlaid hyperboloids are analogous to shearographic carrier fringes. Use of this method for explaining the formation of deformation fringes in plate bending, as well as the effect of light-source movement on the deformation fringes, is also illustrated.
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Cohen TJ, Thayapran N, Ibrahim B, Quan C, Quan W, von zur Muhlen F. An association between anxiety and neurocardiogenic syncope during head-up tilt table testing. Pacing Clin Electrophysiol 2000; 23:837-41. [PMID: 10833703 DOI: 10.1111/j.1540-8159.2000.tb00852.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To study the association between anxiety and neurocardiogenic syncope as determined by head-up tilt table testing (HUT) in men and women with presyncope or syncope, patients with unexplained syncope or presyncope undergoing HUT were asked to complete the Burns Anxiety Inventory (BAI), a validated inventory of 33 questions with responses graded from 0 to 3. HUT consisted of a 30-minute tilt to 60 degrees, which if negative, was repeated with an isoproterenol infusion. A positive HUT was defined as symptomatic hypotension and/or bradycardia. Of the 66 patients who completed the BAI and underwent HUT, 33 were men and 33 were women. The mean age was 57 +/- 18 years (17-91 years). Patients with a positive HUT had a higher BAI score than those with a negative HUT (22 +/- 12 vs 14 +/- 13, P = 0.017). This association was stronger in women with a BAI score of 24 +/- 11 in those with a positive HUT versus 13 +/- 8 in those with a negative HUT (P = 0.005). In contrast, the mean BAI score for men with a positive HUT was 19 +/- 13, as compared to 15 +/- 16 for a negative HUT (P = 0.5). In conclusion, the present study demonstrates a statistical association between anxiety (as determined by BAI) and HUT result. Gender-based analysis revealed a more statistically significant relationship between anxiety and HUT outcome for women as compared to men.
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