73 results on '"Lam AC"'
Search Results
2. Investigating the utility of combining Phi 29 whole genome amplification and highly multiplexed single nucleotide polymorphism BeadArray (TM) genotyping
- Author
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Pask, R, Rance, HE, Barratt, BJ, Nutland, S, Smyth, DJ, Sebastian, M, Twells, RCJ, Smith, A, Lam, AC, Smink, LJ, Walker, NM, Todd, JA, and Apollo - University of Cambridge Repository
- Subjects
displacement amplification ,association ,identification ,samples ,DNA ,accurate ,common disease - Abstract
Background: Sustainable DNA resources and reliable high-throughput genotyping methods are required for large-scale, long-term genetic association studies. In the genetic dissection of common disease it is now recognised that thousands of samples and hundreds of thousands of markers, mostly single nucleotide polymorphisms (SNPs), will have to be analysed. In order to achieve these aims, both an ability to boost quantities of archived DNA and to genotype at low costs are highly desirable. We have investigated Phi29 polymerase Multiple Displacement Amplification (MDA)-generated DNA product (MDA product), in combination with highly multiplexed BeadArray(TM) genotyping technology. As part of a large-scale BeadArray genotyping experiment we made a direct comparison of genotyping data generated from MDA product with that from genomic DNA (gDNA) templates. Results: Eighty-six MDA product and the corresponding 86 gDNA samples were genotyped at 345 SNPs and a concordance rate of 98.8% was achieved. The BeadArray sample exclusion rate, blind to sample type, was 10.5% for MDA product compared to 5.8% for gDNA. Conclusions: We conclude that the BeadArray technology successfully produces high quality genotyping data from MDA product. The combination of these technologies improves the feasibility and efficiency of mapping common disease susceptibility genes despite limited stocks of gDNA samples.
- Published
- 2004
3. Expanding salivary biomarker detection by creating a synthetic neuraminic acid sensor via chimeragenesis.
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Verzino SJ, Priyev SA, Estrada VAS, Crowley GX, Rutkowski A, Lam AC, Nazginov ES, Kotemelo P, Bacelo A, Sukhram DT, Vázquez FX, and Juárez JF
- Abstract
Accurate and timely diagnosis of oral squamous cell carcinoma (OSCC) is crucial in preventing its progression to advanced stages with a poor prognosis. As such, the construction of sensors capable of detecting previously established disease biomarkers for the early and non-invasive diagnosis of this and many other conditions has enormous therapeutic potential. In this work, we apply synthetic biology techniques for the development of a whole-cell biosensor (WCB) that leverages the physiology of engineered bacteria in vivo to promote the expression of an observable effector upon detection of a soluble molecule. To this end, we have constructed a bacterial strain expressing a novel chimeric transcription factor (Sphnx) for the detection of N-acetylneuraminic acid (Neu5Ac), a salivary biomolecule correlated with the onset of OSCC. This WCB serves as the proof-of-concept of a platform that can eventually be applied to clinical screening panels for a multitude of oral and systemic medical conditions whose biomarkers are present in saliva.
- Published
- 2024
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4. Progressively Worsening Scaly Patches and Plaques in an Infant.
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Lam AC, Ostrofe SP, and Ellis RM
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- Humans, Infant, Male, Diagnosis, Differential, Skin Diseases diagnosis
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- 2024
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5. The Effect of Upper Cervical Mobilization/Manipulation on Temporomandibular Joint Pain, Maximal Mouth Opening, and Pressure Pain Thresholds: A Systematic Review and Meta-Analysis.
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Lam AC, Liddle LJ, and MacLellan CL
- Abstract
Objective: To evaluate the efficacy of upper cervical joint mobilization and/or manipulation on reducing pain and improving maximal mouth opening (MMO) and pressure pain thresholds (PPTs) in adults with temporomandibular joint (TMJ) dysfunction compared with sham or other intervention., Data Sources: MEDLINE, CINAHL, EMBASE, and Cochrane Library from inception to June 3, 2022, were searched., Study Selection: Eight randomized controlled trials with 437 participants evaluating manual therapy (MT) vs sham and MT vs other intervention were included. Two reviewers independently extracted data and assessed risk of bias., Data Extraction: Two independent reviewers extracted information about origin, number of study participants, eligibility criteria, type of intervention, and outcome measures., Data Synthesis: Manual therapy was statistically significant in reducing pain compared with sham (mean difference [MD]: -1.93 points, 95% confidence interval [CI]: -3.61 to -0.24, P =.03), and other intervention (MD: -1.03 points, 95% CI: -1.73 to -0.33, P =.004), improved MMO compared with sham (MD: 2.11 mm, 95% CI: 0.26 to 3.96, P =.03), and other intervention (MD: 2.25 mm, 95% CI: 1.01 to 3.48, P <.001), but not statistically significant in improving PPT of masseter compared with sham (MD: 0.45 kg/cm
2 , 95% CI: -0.21 to 1.11, P =.18), and other intervention (MD: 0.42 kg/cm2 , 95% CI: -0.19 to 1.03, P =.18), or the PPT of temporalis compared with sham (MD: 0.37 kg/cm2 , 95% CI: -0.03 to 0.77, P =.07), and other intervention (MD: 0.43 kg/cm2 , 95% CI: -0.60 to 1.45, P =.42)., Conclusion: There appears to be limited benefit of upper cervical spine MT on TMJ dysfunction, but definitive conclusions cannot be made because of heterogeneity and imprecision of treatment effects., (© 2022 The Authors.)- Published
- 2022
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6. Adenoid ameloblastoma harbors beta-catenin mutations.
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Bastos VC, Coura BP, Guimarães LM, Fernandes BG, Chan AC, Vargas PA, Bastos-Rodrigues L, De Marco LA, Hellstein J, Thavaraj S, Wright JM, Odell EW, Gomez RS, and Gomes CC
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- Humans, Male, Female, beta Catenin genetics, beta Catenin metabolism, Proto-Oncogene Proteins B-raf genetics, Proto-Oncogene Proteins p21(ras) genetics, Proto-Oncogene Proteins p21(ras) metabolism, Mutation, Ameloblastoma genetics, Ameloblastoma pathology, Adenoids metabolism, Adenoids pathology, Odontogenic Tumors pathology
- Abstract
Adenoid ameloblastoma is a very rare benign epithelial odontogenic tumor characterized microscopically by epithelium resembling conventional ameloblastoma, with additional duct-like structures, epithelial whorls, and cribriform architecture. Dentinoid deposits, clusters of clear cells, and ghost-cell keratinization may also be present. These tumors do not harbor BRAF or KRAS mutations and their molecular basis appears distinct from conventional ameloblastoma but remains unknown. We assessed CTNNB1 (beta-catenin) exon 3 mutations in a cohort of 11 samples of adenoid ameloblastomas from 9 patients. Two of the 9 patients were female and 7 male and in 7/9 patients the tumors occurred in the maxilla. Tumors of 4 of these 9 patients harbored CTNNB1 mutations, specifically p.Ser33Cys, p.Gly34Arg, and p.Ser37Phe. Notably, for one patient 3 samples were analyzed including the primary tumour and two consecutive recurrences, and results were positive for the mutation in all three tumors. Therefore, 6/11 samples tested positive for the mutation. In the 6 mutation-positive samples, ghost cells were present in only 2/6, indicating beta-catenin mutations are not always revealed by ghost cell formation. Dentinoid matrix deposition was observed in 5/6 mutation-positive samples and clear cells in all 6 cases. None of the cases harbored either BRAF or KRAS mutations. Beta-catenin immunoexpression was assessed in the samples of 8 patients. Except for one wild-type case, all cases showed focal nuclear expression irrespective of the mutational status. Together with the absence of BRAF mutation, the detection of beta-catenin mutation in adenoid ameloblastomas supports its classification as a separate entity, and not as a subtype of ameloblastoma. The presence of this mutation may help in the diagnosis of challenging cases., (© 2022. The Author(s), under exclusive licence to United States & Canadian Academy of Pathology.)
- Published
- 2022
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7. Methodology paper for the General Medicine Inpatient Initiative Medical Education Database (GEMINI MedED): a retrospective cohort study of internal medicine resident case-mix, clinical care and patient outcomes.
- Author
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Lam AC, Tang B, Lalwani A, Verma AA, Wong BM, Razak F, and Ginsburg S
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- Clinical Competence, Humans, Internal Medicine, Retrospective Studies, Inpatients, Internship and Residency
- Abstract
Introduction: Unwarranted variation in patient care among physicians is associated with negative patient outcomes and increased healthcare costs. Care variation likely also exists for resident physicians. Despite the global movement towards outcomes-based and competency-based medical education, current assessment strategies in residency do not routinely incorporate clinical outcomes. The widespread use of electronic health records (EHRs) may enable the implementation of in-training assessments that incorporate clinical care and patient outcomes., Methods and Analysis: The General Medicine Inpatient Initiative Medical Education Database (GEMINI MedED) is a retrospective cohort study of senior residents (postgraduate year 2/3) enrolled in the University of Toronto Internal Medicine (IM) programme between 1 April 2010 and 31 December 2020. This study focuses on senior IM residents and patients they admit overnight to four academic hospitals. Senior IM residents are responsible for overseeing all overnight admissions; thus, care processes and outcomes for these clinical encounters can be at least partially attributed to the care they provide. Call schedules from each hospital, which list the date, location and senior resident on-call, will be used to link senior residents to EHR data of patients admitted during their on-call shifts. Patient data will be derived from the GEMINI database, which contains administrative (eg, demographic and disposition) and clinical data (eg, laboratory and radiological investigation results) for patients admitted to IM at the four academic hospitals. Overall, this study will examine three domains of resident practice: (1) case-mix variation across residents, hospitals and academic year, (2) resident-sensitive quality measures (EHR-derived metrics that are partially attributable to resident care) and (3) variations in patient outcomes across residents and factors that contribute to such variation., Ethics and Dissemination: GEMINI MedED was approved by the University of Toronto Ethics Board (RIS#39339). Results from this study will be presented in academic conferences and peer-reviewed journals., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2022
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8. In vivo analysis of endocanalicular light pipe transillumination in endoscopic dacryocystorhinostomy: Anatomic considerations and cautions for the transitioning.
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Boal NS, Cretara EAZ, Bleier BS, Lam AC, and Lefebvre DR
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- Endoscopy, Humans, Retrospective Studies, Transillumination, Dacryocystorhinostomy, Lacrimal Duct Obstruction diagnosis, Nasolacrimal Duct surgery
- Abstract
Purpose: Localization of the lacrimal sac is a critical step during endoscopic dacryocystorhinostomy (endo-DCR). A "light pipe" can be used to transilluminate the lacrimal sac endonasally. We hypothesized that this may misguide the surgeon learning endo-DCR to create an osteotomy mostly posterior to the maxillary line if only the bone overlying the transillumination was to be removed, as the thinner lacrimal bone will transmit light more readily than the thicker maxillary bone of the frontal process of the maxilla that forms the anterior lacrimal sac fossa., Methods: The charts of 32 patients with primary acquired nasolacrimal duct obstruction in whom a lighted system was used during endo-DCR at Massachusetts Eye and Ear from April 2015 through October 2016 were reviewed. Patients with prior history of lacrimal surgery or trauma directly to the lacrimal sac fossa were excluded. Location of the maximal point of transillumination in relation to the maxillary line was observed and noted intraoperatively., Results: Of a total of 39 endo-DCR surgeries performed, the intraoperative transillumination point was entirely posterior to the maxillary line in 32 instances (82%)., Conclusions: Use of an endocanalicular light pipe preferentially illuminates posterior to the maxillary line endonasally. The anterior lacrimal sac fossa (maxillary line and anterior as visualized endonasally) is rarely transilluminated, likely due to thicker bone in that region. Surgeons learning how to perform endo-DCR using a light pipe should be aware of this phenomenon.
- Published
- 2022
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9. Stratification and management of patients ineligible for lung cancer screening.
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Aggarwal R, Lam AC, Huang J, Hueniken K, Nguyen D, Khan K, Shaikh T, Shepherd FA, Tsao MS, Xu W, Kavanagh J, and Liu G
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- Adult, Aged, Canada, Early Detection of Cancer, Educational Status, Humans, Longitudinal Studies, Middle Aged, Pulmonary Disease, Chronic Obstructive complications, Risk Assessment, Smoking adverse effects, Eligibility Determination statistics & numerical data, Lung Neoplasms diagnosis, Mass Screening statistics & numerical data, Patient Selection
- Abstract
This study identifies participants ineligible for lung cancer screening with the greatest likelihood of future eligibility. Lung cancer risk in participants enrolled in longitudinal lung screening was assessed using the Prostate, Lung, Colorectal and Ovarian lung cancer risk calculator (PLCO
m2012 ) at two timepoints: baseline (T1 ) and follow-up (T2 ). Separate analyses were performed on four PLCOm2012 eligibility thresholds (3.25%, 2.00%, 1.50%, and 1.00%); only participants with a T1 risk less than the threshold were included in that analysis. Cox-models identified T1 risk factors associated with screen-eligibility at T2 . Three models, applying differing assumptions of participant behavior, predicted future eligibility and were benchmarked against the observed cohort. Nine hundred and fifty-six participants had a T1 risk <3.25%; at 2.00% n= 755; at 1.50% n= 652; at 1.00% n= 484. Lung cancer risk increased over time in most screen-ineligible participants. However, risk increased much faster in participants who became screen-eligible at T2 compared to those who remained screen-ineligible (median per-year increase of 0.35% versus 0.02%, when using a 3.25% threshold). Participants smoking for >30 years, current smokers, less educated participants, and those with chronic obstructive pulmonary disease (COPD) at T1 were significantly more likely to become screen-eligible. New diagnoses of COPD and/or non-lung cancers between T1 and T2 precipitated eligibility in a subset of participants. The prediction model that assumed health behaviors observed at T1 continued to T2 reasonably predicted changes in lung cancer risk. This prediction model and the identified baseline risk factors can identify screen-ineligible participants who should be closely followed for future eligibility., (Copyright © 2021 Elsevier Ltd. All rights reserved.)- Published
- 2021
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10. Clinical outcomes following high-dose-rate surface applicator brachytherapy for angiosarcoma of scalp and face.
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Mitra D, Devlin PM, Buzurovic I, Thornton K, Lam AC, Raut CP, Baldini EH, and Lam MB
- Abstract
Purpose: Angiosarcoma is a sub-type of soft tissue sarcoma, often presenting as a multifocal or diffuse disease process with poor prognosis. This study presents outcomes of a single institution cohort of patients with angiosarcoma of the scalp and face following treatment with multimodality therapy, including high-dose-rate surface applicator (HDR-SA) brachytherapy, and represents the largest cohort utilizing this therapeutic approach., Material and Methods: Twenty patients with primary or recurrent angiosarcoma of the face or scalp were treated with HDR-SA brachytherapy between 2003-2018, with clinical characteristics and outcomes collected from medical records and used to identify prognostic features., Results: Median follow-up was 45 months. Patients treated with HDR-SA brachytherapy had a 4-year local control rate of 63%, a 4-year progression-free survival (PFS) rate of 20%, and a 4-year overall survival rate of 54%. Disease features associated with worse loco-regional control (LRC) included location on the scalp (vs. face, p = 0.04) and tumor size ≥ 5 cm ( p = 0.0099). Outcomes after HDR-SA brachytherapy for salvage therapy vs. HDR-SA brachytherapy as a component of an initial treatment approach were also significantly different, with worse LRC ( p = 0.0084) and worse overall survival (OS) ( p = 0.0019) in a setting of salvage therapy., Conclusions: Local control rates following HDR-SA brachytherapy for scalp or face angiosarcoma are moderate and similar to what is described in the literature using a variety of local control treatment modalities. Smaller tumors and those involving the face rather than scalp had better outcomes. PFS rates were poor and there is a pressing need for treatment intensification and novel therapeutic options., Competing Interests: The authors report no conflict of interest., (Copyright © 2021 Termedia.)
- Published
- 2021
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11. Microcystic Adnexal Carcinoma of the Face Treated With Definitive Chemoradiation: A Case Report and Review of the Literature.
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Kim DW, Lee G, Lam MB, Harris EJ, Lam AC, Thomas T, Chau NG, and Tishler RB
- Published
- 2019
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12. Trimodality therapy for HPV-positive oropharyngeal cancer: A population-based study: Trimodality therapy for HPV+ OPC.
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Sanford NN, Hwang WL, Pike LRG, Lam AC, Royce TJ, and Mahal BA
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- Aged, Combined Modality Therapy, Disease Susceptibility, Female, Humans, Kaplan-Meier Estimate, Male, Middle Aged, Neoplasm Metastasis, Neoplasm Staging, Oropharyngeal Neoplasms diagnosis, Oropharyngeal Neoplasms epidemiology, Papillomavirus Infections epidemiology, Papillomavirus Infections virology, Population Surveillance, SEER Program, Treatment Outcome, Oropharyngeal Neoplasms etiology, Oropharyngeal Neoplasms therapy, Papillomaviridae, Papillomavirus Infections complications
- Abstract
Background: Although HPV status is a well-established prognostic factor in oropharyngeal squamous cell carcinoma (OPSCC), approximately 20% of HPV-positive patients die from their disease. We therefore sought to ascertain whether there is a benefit to trimodality therapy with surgery among patients with locally advanced (LA) disease receiving chemoradiation., Methods: The SEER Head and Neck with HPV Status Database identified adult patients with non-metastatic OPSCC between 2013 and 2014 with known HPV status who received chemoradiation as part of definitive treatment. The primary outcome was cancer-specific mortality (CSM) for locally-advanced (LA) (T3-T4, or N2-N3, per AJCC 7) versus early-stage (ES) (T1-T2 and N0-N1) disease, stratified by HPV status. The secondary outcome was overall survival (OS)., Results: Among 2974 patients who met study criteria, 671 patients (22.6%) received upfront surgery (trimodality therapy). In the LA setting, there was a significant reduction in CSM with trimodality therapy compared to chemoradiation alone in HPV-positive (Adjusted Hazard Ratio [AHR] 0.19, 95% Confidence Interval [CI] 0.04-0.80; P = 0.024), but not HPV-negative disease [P
interaction = 0.04]. There was no benefit to trimodality therapy for ES disease, regardless of HPV status. There was also an improvement in OS with trimodality therapy for HPV-positive LA patients (AHR = 0.28, p = 0.006, 95% CI = 0.11-0.70). In contrast, trimodality therapy was not associated with improved OS for HPV-negative patients regardless of stage., Conclusions: HPV status may predict for improved outcomes with surgery/trimodality therapy in LA OPSCC. Our findings support prospective investigations to optimize care for the subset of HPV-positive patients who are at greatest risk of cancer death, where trimodality therapy may be appropriate., (Copyright © 2019 Elsevier Ltd. All rights reserved.)- Published
- 2019
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13. Phase III Randomized Pair Comparison of a Barrier Film vs. Standard Skin Care in Preventing Radiation Dermatitis in Post-lumpectomy Patients with Breast Cancer Receiving Adjuvant Radiation Therapy.
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Lam AC, Yu E, Vanwynsberghe D, O'Neil M, D'Souza D, Cao J, and Lock M
- Abstract
Introduction Patients undergoing adjuvant radiotherapy to the breast often experience radiation dermatitis ranging from mild erythema to moist desquamation. In post-lumpectomy patients, the axilla and inframammary fold are at an increased risk for friction dermatitis. Dermatitis can impact patients' quality-of-life and may require treatment break/cessation. Our objectives are to assess the efficacy of 3M Cavilon Barrier Film (BF) in preventing and/or delaying the onset of grade-two dermatitis and reducing patient-reported sensation scores. Methods A total of 55 patients were randomized to receive BF on the medial or lateral breast. BF was applied twice weekly during treatment. Skin toxicity was evaluated weekly by a blinded clinical investigator using the Skin Toxicity Assessment Tool (STAT) and the modified Radiation Therapy Oncology Group Visual Assessment Score (RTOG VAS). On day one, baseline photographs were taken; seven-to-ten days post-treatment, patients returned for photographs, the STAT/RTOG VAS, and patient-opinion questions in the form of the global questionnaire. Results The paired analysis found BF did not significantly reduce dermatitis either during or post-treatment. However, the unpaired analysis found significantly reduced RTOG VAS on the lateral compartment during treatment (BF:0.91 vs. Control:1.21, p = 0.0408). This difference resolved post-treatment. Additionally, BF was able to reduce pruritus ( p = 0.047) on the medial components and burning sensations on the lateral components ( p = 0.035). There was no significant difference between the time-to-onset or proportion of patients who developed grade-two dermatitis. Conclusion In an unpaired analysis, BF significantly reduced dermatitis on the lateral compartment during treatment. Additionally, BF significantly reduced pruritus and burning sensations. A larger study using a more reliable scoring method is required to clarify the effect of BF on radiation-associated skin toxicity., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2019
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14. Editorial on "Can navigation-assisted surgery help achieve negative margins in resection of pelvic and sacral tumor?"
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Lam YL and Chan AC
- Abstract
Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.
- Published
- 2018
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15. What Do Patients Want from Otolaryngologists? A Discrete Choice Experiment.
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Naunheim MR, Rathi VK, Naunheim ML, Alkire BC, Lam AC, Song PC, and Shrime MG
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- Adult, Female, Humans, Logistic Models, Male, Surveys and Questionnaires, Choice Behavior, Clinical Competence, Decision Making, Otolaryngologists standards, Patient Preference psychology, Patient-Centered Care standards
- Abstract
Objectives Patient preferences are crucial for the delivery of patient-centered care. Discrete choice experiments (DCEs) are an emerging quantitative methodology used for understanding these preferences. In this study, we employed DCE techniques to understand the preferences of patients presenting for an ear, nose, and throat clinic visit. Study Design DCE. Setting Decision science laboratory. Methods A DCE survey of 5 attributes-wait time, physician experience, physician personality, utilization of visit time, and cost/copayment-was constructed with structured qualitative interviews with patients. The DCE was administered to participants from the general population, who chose among hypothetical scenarios that varied across these attributes. A conditional logit model was used to determine relative attribute importance, with a separate logit model for determining subject effects. Results A total of 161 participants were included. Cost/copayment had the greatest impact on decision making (importance, 32.2%), followed by wait time and physician experience (26.5% and 24.7%, respectively). Physician personality mattered least (4.7%), although all attributes were significantly correlated to decision making. Participants preferred doctors who spent more time performing physical examination than listening or explaining. Participants were willing to pay $52 extra to avoid a 4-week delay in appointment time; $87 extra for a physician with 10 years of experience (vs 0 years); and $9 extra for a caring, friendly, and compassionate doctor (vs formal, efficient, and business-like). Conclusion DCEs allow for powerful economic analyses that may help physicians understand patient preferences. Our model showed that cost is an important factor to patients and that patients are willing to pay extra for timely appointments, experience, and thorough physical examination.
- Published
- 2017
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16. A cross-sectional study of the knowledge, attitude, and practice of patients aged 50 years or above towards herpes zoster in an out-patient setting.
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Lam AC, Chan MY, Chou HY, Ho SY, Li HL, Lo CY, Shek KF, To SY, Yam KK, and Yeung I
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- Aged, Cross-Sectional Studies, Female, Herpes Zoster prevention & control, Hong Kong, Humans, Male, Middle Aged, Surveys and Questionnaires, Health Knowledge, Attitudes, Practice, Herpes Zoster psychology, Herpes Zoster Vaccine therapeutic use, Outpatients psychology, Vaccination psychology
- Abstract
Introduction: There has been limited research on the knowledge of and attitudes about herpes zoster in the Hong Kong population. This study aimed to investigate the knowledge, attitude, and practice of patients aged 50 years or above towards herpes zoster and its vaccination., Methods: This was a cross-sectional study in the format of a structured questionnaire interview carried out in Sai Ying Pun Jockey Club General Outpatient Clinic in Hong Kong. Knowledge of herpes zoster and its vaccination was assessed, and patient attitudes to and concerns about the disease were evaluated. Factors that affected a decision about vaccination against herpes zoster were investigated., Results: A total of 408 Hong Kong citizens aged 50 years or above were interviewed. Multiple regression analysis revealed that number of correct responses regarding knowledge about herpes zoster was positively correlated with educational attainment (B=0.313, P=0.026) and history of herpes zoster (B=0.408, P=0.038), and negatively correlated with age (B= -0.042, P<0.001) and male gender (B= -0.396, P=0.029). Answers to several questions revealed a sizable number of misconceptions about the disease. Among all respondents, 35% stated that they were worried about getting the disease, and 17% would consider vaccination against herpes zoster., Conclusions: Misconceptions about herpes zoster were notable in this study. More health education is needed to improve the understanding and heighten awareness of herpes zoster among the general public. Although the majority of participants indicated that herpes zoster would have a significant impact on their health, a relatively smaller proportion was actually worried about getting the disease. Further studies on this topic should be encouraged to gauge the awareness and knowledge of herpes zoster among broader age-groups.
- Published
- 2017
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17. Aseptic Meningitis with Craniopharyngioma Resection: Consideration after Endoscopic Surgery.
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Chen JX, Alkire BC, Lam AC, Curry WT, and Holbrook EH
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Objectives While bacterial meningitis is a concerning complication after endoscopic skull base surgery, the diagnosis can be made without consideration for aseptic meningitis. This article aims to (1) present a patient with recurrent craniopharyngioma and multiple postoperative episodes of aseptic meningitis and (2) discuss the diagnosis and management of aseptic meningitis. Design Case report and literature review. Results A 65-year-old female patient with a symptomatic craniopharyngioma underwent transsphenoidal resection. She returned postoperatively with symptoms concerning for cerebrospinal fluid (CSF) leak and bacterial meningitis. Lumbar puncture demonstrated mildly elevated leukocytes with normal glucose levels. Cultures were sterile and she was discharged on antibiotics. She returned 18 days postoperatively with altered mental status and fever. Again, negative CSF cultures suggested aseptic meningitis. Radiological and intraoperative findings were now concerning for widespread cerebrovascular vasospasm due to leaked craniopharyngioma fluids. In the following months, her craniopharyngioma recurred and required multiple surgical resections. Days after her last operation, she returned with mental status changes and a sterile CSF culture. She was diagnosed with recurrent aseptic meningitis and antibiotics were discontinued. The patient experienced near complete resolution of symptoms. Conclusions Consideration of aseptic meningitis following craniopharyngioma resection is critical to avoid unnecessary surgical re-exploration and prolonged courses of antibiotics.
- Published
- 2016
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18. The influence of precompression on elasticity of thyroid nodules estimated by ultrasound shear wave elastography.
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Lam AC, Pang SW, Ahuja AT, and Bhatia KS
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- Adult, Carcinoma diagnosis, Carcinoma, Papillary, Elasticity, Female, Humans, Male, Thyroid Cancer, Papillary, Thyroid Neoplasms diagnosis, Elasticity Imaging Techniques methods, Thyroid Nodule diagnosis, Ultrasonography methods
- Abstract
Objectives: To investigate the influence of variations in resting pressure (precompression) on thyroid ultrasound supersonic shear wave elastography (SWE)., Methods: Thirty-five normal thyroid glands (Norm), 55 benign hyperplastic nodules (BHN), and 17 papillary thyroid cancers (PTC) in 96 subjects underwent thyroid SWE. Four precompression levels were applied manually by the operator, ranging from A (baseline, 0 % strain) to D (high, 22-30 % strain). SWE results at each precompression level were compared using ANOVA tests with P < 0.05 indicating significance., Results: SWE indices were highest in PTC, followed by BHN and Norm at each precompression level (P < 0.05). All tissue types showed successive increases in SWE results as precompression increased, although the rate was higher for PTC than BHN and Norm (Ps < 0.05). SWE values (kPa) of Norm, BHN, and PTC at baseline precompression (A) were 10.3 ± 3.3, 17.7 ± 7.6, and 22.2 ± 11.9 compared with 21.1 ± 4.2, 42.3 ± 16.0, and 97.6 ± 46.8 at high precompression (D). SWE index differences between precompression levels A and D were 10.8 kPa for Norm, 24.6 kPa for BHN, and 75.4 kPa for PTC., Conclusion: PTCs show greater SWE stiffening than BHN as precompression rises. Precompression effects on thyroid nodules are not negligible and may account for wide discrepancies in published SWE discriminatory performance results for thyroid malignancy., Key Points: • Increases in resting pressure (precompression) applied by the operator increases thyroid stiffness. • Papillary cancers show greater increases in stiffness (strain hardening) than benign nodules. • Precompression may affect the diagnostic performance of shearwave elastography for thyroid malignancy.
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- 2016
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19. Feasibility Study of Texture Analysis Using Ultrasound Shear Wave Elastography to Predict Malignancy in Thyroid Nodules.
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Bhatia KS, Lam AC, Pang SW, Wang D, and Ahuja AT
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- Adolescent, Adult, Aged, Aged, 80 and over, Diagnosis, Differential, Feasibility Studies, Female, Humans, Male, Middle Aged, Prospective Studies, Reproducibility of Results, Sensitivity and Specificity, Thyroid Gland diagnostic imaging, Young Adult, Elasticity Imaging Techniques methods, Thyroid Nodule diagnostic imaging
- Abstract
Textural analysis of ultrasound shear wave elastography (SWE) was evaluated to discriminate benign and malignant thyroid nodules. Sixteen papillary thyroid cancers and 89 benign hyperplastic nodules in 105 patients underwent SWE using four static pre-compression levels. Fifteen gray level co-occurrence matrix textural features and six absolute SWE indices were computed from SWE images. Diagnostic performances of each SWE index for malignancy were calculated and compared using the area under the receiver operating characteristic curve (AUC), and optimal models were generated at each pre-compression level. The optimal model comprised two SWE textural features at the highest pre-compression level, which attained AUC, sensitivity and specificity of 0.973, 97.5% and 90.0%, respectively. By comparison, absolute SWE indices attained AUC of 0.709 as well as 18.8% sensitivity and 95.8% specificity. These preliminary results suggest SWE textural analysis can distinguish benign and malignant thyroid nodules and SWE spatial heterogeneity is greater in malignant nodules., (Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2016
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20. A rare disease in an atypical location-Kimura's Disease of the upper extremity.
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Lam AC, Au Yeung RK, and Lau VW
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- Humans, Male, Middle Aged, Rare Diseases pathology, Rare Diseases surgery, Treatment Outcome, Angiolymphoid Hyperplasia with Eosinophilia pathology, Angiolymphoid Hyperplasia with Eosinophilia surgery, Magnetic Resonance Imaging methods, Upper Extremity pathology, Upper Extremity surgery
- Abstract
Kimura's disease is a rare chronic inflammatory disorder predominantly affecting young Asian male patients, occurring mainly in the head and neck regions. Kimura's disease of the upper extremity is extremely rare, and previous case reports in the literature show similar imaging characteristics with consistent location at the medial epitrochlear region, predominantly with unilateral involvement. We present the first reported case of Kimura's disease affecting the anterolateral aspect of the upper arm, sparing the medial epitrochlear region, illustrating that with typical MR appearance and serology, the involvement of this rare disease in an atypical location still warrants consideration of this diagnosis. There was also bilateral asymmetrical involvement in our patient, suggesting the possibility of a propensity for Kimura's disease affecting the upper extremities to have bilateral involvement, which may necessitate imaging of the clinically asymptomatic contralateral limb in these patients for early lesion identification and treatment.
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- 2015
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21. Heat Damage Zones Created by Different Energy Sources Used in the Treatment of Benign Prostatic Hyperplasia in a Pig Liver Model.
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Kan CF, Chan AC, Pun CT, Ho LY, Chan SW, and Au WH
- Subjects
- Animals, Disease Models, Animal, Humans, Laser Therapy methods, Male, Postoperative Complications prevention & control, Swine, Transurethral Resection of Prostate methods, Treatment Outcome, Hot Temperature, Laser Therapy adverse effects, Liver pathology, Postoperative Complications etiology, Prostatic Hyperplasia surgery, Transurethral Resection of Prostate adverse effects
- Abstract
Introduction: There are different types of transurethral prostatic surgeries and the complication profiles are different. This study aims to compare the heat damage zones (HDZ) created by five different technologies in a pig liver model., Materials and Methods: Monopolar resection, bipolar resection, electrovaporization, and Greenlight™ lasers of 120 and 180 W were used to remove fresh pig liver tissue in a simulated model. Each procedure was repeated in five specimens. Two blocks were selected from each specimen to measure the three deepest HDZ., Results: The mean of HDZ was 295, 234, 192, 673, and 567 μm, respectively, for monopolar resection, bipolar resection, electrovaporization, Greenlight laser 120 W, and Greenlight laser 180 W, respectively. The Greenlight laser produced one to three times deeper HDZ than the other energy sources (p=0.000)., Conclusion: Both 120 and 180 W Greenlight lasers produced deeper HDZ than the other energy sources. Urologists need to be aware of HDZ that cause tissue damage outside the operative field.
- Published
- 2015
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22. Primary tracheoesophageal puncture with supraclavicular artery island flap after total laryngectomy or laryngopharyngectomy.
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Sethi RK, Kozin ED, Lam AC, Emerick KS, and Deschler DG
- Subjects
- Aged, Carcinoma, Squamous Cell mortality, Carcinoma, Squamous Cell pathology, Clavicle blood supply, Combined Modality Therapy, Female, Follow-Up Studies, Graft Rejection, Graft Survival, Humans, Laryngeal Neoplasms mortality, Laryngeal Neoplasms pathology, Laryngectomy methods, Male, Middle Aged, Neoplasm Invasiveness pathology, Neoplasm Staging, Pharyngeal Neoplasms mortality, Pharyngeal Neoplasms pathology, Pharyngectomy methods, Quality of Life, Retrospective Studies, Risk Assessment, Treatment Outcome, Carcinoma, Squamous Cell surgery, Laryngeal Neoplasms surgery, Larynx, Artificial, Pharyngeal Neoplasms surgery, Punctures methods, Plastic Surgery Procedures methods, Surgical Flaps blood supply
- Abstract
The supraclavicular artery island flap (SCAIF) is increasingly employed for laryngectomy reconstruction with excellent success. Although tracheoesophageal puncture (TEP) with intraoperative prosthesis placement is also positively reported, this is not described in patients following SCAIF. We review our experience with primary TEP with prosthesis placement and voice outcomes in patients after SCAIF reconstruction. Seven patients underwent SCAIF with primary TEP after laryngectomy from 2011 to 2013. Five underwent total laryngectomy (TL) and 2 underwent TL with partial pharyngectomy. All patients had 16 French Indwelling Blom-Singer prostheses placed intraoperatively without complications. Six patients achieved tracheoesophageal voice (median time = 1.5 months). Two patients required cricopharyngeal segment Botox injections. One patient remained aphonic. One patient developed prosthesis leakage addressed with prosthesis replacement. Our preliminary data demonstrate that similar to free tissue transfer reconstruction, primary TEP with intraoperative placement of the voice prosthesis at the time of SCAIF reconstruction is safe and effective., (© American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.)
- Published
- 2014
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23. P-glycoprotein is a marker of tissue eosinophilia and radiographic inflammation in chronic rhinosinusitis without nasal polyps.
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Feldman RE, Lam AC, Sadow PM, and Bleier BS
- Subjects
- Adult, Chronic Disease, Female, Humans, Male, Middle Aged, Radiography, Rhinitis diagnostic imaging, Sinusitis diagnostic imaging, ATP Binding Cassette Transporter, Subfamily B metabolism, Eosinophils metabolism, Nasal Mucosa metabolism, Paranasal Sinuses metabolism, Rhinitis metabolism, Sinusitis metabolism
- Abstract
Background: P-glycoprotein (P-gp) is a membrane-bound efflux pump that is upregulated in chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) and participates in epithelial cytokine secretion. Eosinophilic CRS (ECRS) shares a similar cytokine profile with CRSwNP and is associated with significant inflammation and poor surgical outcomes. The goal of this study is to determine if P-gp expression is associated with degree of eosinophilia and severity of radiographic inflammation in patients with CRS without polyps (CRSsNP)., Methods: An institutional review board (IRB)-approved study using sinus tissue in 39 steroid-naive patients with CRS. P-gp expression was calculated using quantitative fluorescent immunohistochemistry (Q-FIHC) to generate an epithelial to background staining ratio. Patients were stratified into low and high epithelial expression groups (<3 and ≥3, respectively). Average eosinophils per high powered field (hpf) and Lund-Mackay scores were calculated and compared with P-gp staining ratios using a 2-tailed Student t test., Results: Among the 39 patients, 7 (17.95%) had high P-gp expression ratios (mean ± SD, 4.86 ± 1.33) while 32 (82.05%) had low expression ratios (1.91 ± 0.45). The number of eosinophils/hpf were significantly greater in the high P-gp expression group as compared to the low expression group (62.38 ± 83.69 vs 5.11 ± 10.12, p = 0.0003). The Lund-Mackay scores were significantly greater in the high P-gp expression group as compared to the low expression group (11.86 ± 2.79 vs 6.84 ± 4.19, p = 0.005)., Conclusion: P-gp is known to be overexpressed in CRSwNP. This study suggests that among patients with CRSsNP, P-gp is similarly overexpressed in those with high tissue eosinophilia and correlates with severity of radiographic inflammation., (© 2013 The Authors. International Forum of Allergy & Rhinology, published by Wiley Periodicals, Inc., on behalf of ARS-AAOA, LLC.)
- Published
- 2013
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24. The multiple stressor effect in zebrafish embryos from simultaneous exposure to ionising radiation and cadmium.
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Ng CY, Choi VW, Lam AC, Cheng SH, and Yu KN
- Subjects
- Adaptation, Physiological drug effects, Adaptation, Physiological radiation effects, Animals, Dose-Response Relationship, Drug, Embryo, Nonmammalian drug effects, Embryo, Nonmammalian radiation effects, Radiation Dosage, Radiation Tolerance physiology, Stress, Physiological drug effects, Stress, Physiological radiation effects, Adaptation, Physiological physiology, Cadmium administration & dosage, Embryo, Nonmammalian physiology, Radiation Tolerance drug effects, Radiation Tolerance radiation effects, Stress, Physiological physiology, Zebrafish embryology
- Abstract
Living organisms are exposed to a mixture of environmental stressors, and the resultant effects are referred to as multiple stressor effects. In the present work, we studied the multiple stressor effect in embryos of the zebrafish (Danio rerio) from simultaneous exposure to ionising radiation (alpha particles) and cadmium through quantification of apoptotic signals at 24 h postfertilisation (hpf) revealed by vital dye acridine orange staining. For each set of experiments, 32-40 dechorionated embryos were deployed, which were divided into four groups each having 8-10 embryos. The four groups of embryos were referred to as (1) the control group (C), which received no further treatments after dechorionation; (2) the Cd-dosed and irradiated group (CdIr), which was exposed to 100 μM Cd from 5 to 24 hpf, and also received about 4.4 mGy from alpha particles at 5 hpf; (3) the irradiated group (Ir), which received about 4.4 mGy from alpha particles at 5 hpf; and (4) the Cd-dosed group (Cd), which was exposed to 100 μM Cd from 5 to 24 hpf. In general, the CdIr, Ir and Cd groups had more apoptotic signals than the C group. Within the 12 sets of experimental results, two showed significant synergistic effects, one showed a weakly synergistic effect and nine showed additive effects. The multiple stressor effect of 100 μM Cd with ~4.4 mGy alpha-particle radiation resulted in an additive or synergistic effect, but no antagonistic effect. The failure to identify significant synergistic effects for some sets of data, and thus their subsequent classification as additive effects, might be a result of the relatively small magnitude of the synergistic effects. The results showed that the radiation risk could be perturbed by another environmental stressor such as a heavy metal, and as such a realistic human radiation risk assessment should in general take into account the multiple stressor effects.
- Published
- 2013
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25. Blockade of orexin receptors with Almorexant reduces cardiorespiratory responses evoked from the hypothalamus but not baro- or chemoreceptor reflex responses.
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Iigaya K, Horiuchi J, McDowall LM, Lam AC, Sediqi Y, Polson JW, Carrive P, and Dampney RA
- Subjects
- Animals, Bicuculline pharmacology, Dose-Response Relationship, Drug, GABA-A Receptor Antagonists pharmacology, Hypothalamus physiology, Male, Orexin Receptors, Rats, Rats, Sprague-Dawley, Acetamides pharmacology, Baroreflex drug effects, Chemoreceptor Cells drug effects, Hypothalamus drug effects, Isoquinolines pharmacology, Receptors, G-Protein-Coupled antagonists & inhibitors, Receptors, Neuropeptide antagonists & inhibitors
- Abstract
Orexin neurons form a restricted group in the dorsal hypothalamus. The group is centered on the perifornical area within the classic hypothalamic defense area, an area which when activated produces marked cardiovascular and respiratory effects. Central administration of orexin can produce cardiorespiratory effects, but the extent to which orexin contributes to such responses evoked from the perifornical hypothalamus is not clear. To determine this, we used the dual orexin receptor antagonist Almorexant to challenge the cardiorespiratory effects evoked by disinhibition of the perifornical hypothalamus. Bicuculline (10 and 20 pmol) was microinjected in the perifornical area before and after administration of Almorexant (15 mg/kg iv) or vehicle in urethane-anesthetized rats. Almorexant significantly reduced the pressor, tachycardic, renal sympathoexcitatory, and tachypneic responses to bicuculline (10 pmol, by 55%, 53%, 28%, 77%; 20 pmol, by 54%, 27%, 51%, 72%, respectively). Reductions of similar magnitude were observed with bicuculline microinjections centered on more caudal sites just peripheral to the orexin neuron group, which would likely have activated fewer orexin neurons. In contrast, Almorexant had no effect on the cardiorespiratory response of the chemoreflex (sodium cyanide injection) or the sympathetic component of the baroreflex. Thus orexin makes a major contribution to the cardiorespiratory response evoked from the perifornical area even though orexin neurons represent only a fraction of the output of this area. Orexin neurons may also mediate cardiorespiratory responses from non-orexin neurons in the caudal hypothalamus. However, under resting conditions, blockade of orexin receptors does not affect the chemo- and baroreflexes.
- Published
- 2012
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26. Functional survival after acute care for severe head injury at a designated trauma center in Hong Kong.
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Taw BB, Lam AC, Ho FL, Hung KN, Lui WM, and Leung GK
- Subjects
- Adult, Aged, Aged, 80 and over, Brain Injuries mortality, Brain Injuries rehabilitation, Emergency Treatment, Female, Follow-Up Studies, Hong Kong, Humans, Logistic Models, Male, Middle Aged, Recovery of Function, Retrospective Studies, Survival Rate, Treatment Outcome, Brain Injuries therapy, Trauma Centers statistics & numerical data
- Abstract
Background: Severe head injury is known to be a major cause of early mortalities and morbidities. Patients' long-term outcome after acute care, however, has not been widely studied. We aim to review the outcome of severely head-injured patients after discharge from acute care at a designated trauma center in Hong Kong., Materials and Methods: This is a retrospective study of prospectively collected data of patients admitted with severe head injuries between 2004 and 2008. Patients' functional status post-discharge was assessed using the Extended Glasgow Outcome Score (GOSE)., Results: Of a total of 1565 trauma patients, 116 had severe head injuries and 41 of them survived acute hospital care. Upon the last follow-up, 23 (56.1%) of the acute-care survivors had improvements in their GOSE, six (11.8%) experienced deteriorations, and 12 (23.5%) did not exhibit any change. The greatest improvement was observed in patients with GOSE of 5 and 6 upon discharge, but two of the 16 patients with GOSE 2 or 3 also had a good recovery. On logistic regression analysis, old age and prolonged acute hospital stay were found to be independent predictors of poor functional outcome after a mean follow-up duration of 42 months., Conclusion: Multidisciplinary neurorehabilitation service is an important component of comprehensive trauma care. Despite significant early mortalities, a proportion of severely head-injured patients who survive acute care may achieve good long-term functional recovery., (Copyright © 2012, Asian Surgical Association. Published by Elsevier Taiwan LLC. All rights reserved.)
- Published
- 2012
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27. Prader--Willi syndrome: 16-year experience in Hong Kong.
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Lo IF, Luk HM, Tong TM, Lai KK, Chan DH, Lam AC, Chan DK, Hau EW, Fung CO, and Lam ST
- Subjects
- Genetic Association Studies, Genetic Testing, Genome, Human, Hong Kong epidemiology, Humans, Prader-Willi Syndrome epidemiology, Prader-Willi Syndrome pathology, Retrospective Studies, Chromosome Deletion, Chromosomes, Human, Pair 15 genetics, Prader-Willi Syndrome genetics
- Published
- 2012
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28. Premenstrual syndrome and dysmenorrhea in adolescents.
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Allen LM and Lam AC
- Subjects
- Adolescent, Anti-Inflammatory Agents, Non-Steroidal therapeutic use, Antidepressive Agents therapeutic use, Body Mass Index, Contraceptives, Oral, Combined therapeutic use, Diet, Dysmenorrhea etiology, Dysmenorrhea therapy, Female, Humans, Premenstrual Syndrome therapy, Severity of Illness Index, Smoking adverse effects, Dysmenorrhea epidemiology, Premenstrual Syndrome drug therapy, Premenstrual Syndrome epidemiology
- Abstract
PMS/PMDD is a pervasive problem with a significant impact on the quality of life of affected individuals. This condition most often begins in adolescence with the establishment of normal ovulatory menstrual cycles; however, the underlying pathophysiology has yet to be delineated. Prospective evaluation is key to the confirmation of the diagnosis before the initiation of pharmacotherapy, especially psychotropic therapies, due to the possibly harmful side effect profile for adolescents compared to adults. Similarly, dysmenorrhea is common in adolescents. Although the majority of cases are primary, the HCP must be vigilant to allow for early diagnosis and treatment of secondary causes, thereby preventing long-term sequelae of delayed diagnosis. Stepwise therapy for dysmenorrhea treatment is usually employed; the choice of therapy should account for contraceptive needs of the adolescent in addition to symptom relief. For both PMSS/PMDD and dysmenorrhea, most studies of therapy have been performed in adults and, as such, adolescent-specific trials are required to confirm applicability to this age group.
- Published
- 2012
29. Rosai-Dorfman disease-like changes in mesenteric lymph nodes secondary to Salmonella infection.
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Ip YT, Loo KT, Ting SH, and Chan AC
- Subjects
- Adolescent, Histiocytosis, Sinus etiology, Humans, Mesentery pathology, Salmonella Infections pathology, Histiocytosis, Sinus pathology, Lymph Nodes pathology, Salmonella Infections complications
- Published
- 2011
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30. Fetal stromal niches enhance human embryonic stem cell-derived hematopoietic differentiation and globin switch.
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Lee KY, Fong BS, Tsang KS, Lau TK, Ng PC, Lam AC, Chan KY, Wang CC, Kung HF, Li CK, and Li K
- Subjects
- Animals, Cell Line, Cell Proliferation drug effects, Colony-Forming Units Assay, Culture Media, Conditioned pharmacology, Embryoid Bodies cytology, Embryoid Bodies drug effects, Embryonic Stem Cells drug effects, Embryonic Stem Cells metabolism, Gene Expression Regulation drug effects, Globins metabolism, Humans, Leukocyte Common Antigens genetics, Leukocyte Common Antigens metabolism, Mice, Stem Cell Niche drug effects, Stem Cell Niche metabolism, Stromal Cells cytology, Stromal Cells drug effects, Stromal Cells metabolism, beta-Globins genetics, beta-Globins metabolism, Cell Differentiation drug effects, Cell Differentiation genetics, Embryonic Stem Cells cytology, Fetus cytology, Globins genetics, Hematopoiesis drug effects, Hematopoiesis genetics, Stem Cell Niche cytology
- Abstract
Hematopoiesis during mammalian embryonic development has been perceived as a migratory phenomenon, from the yolk sac blood island to the aorta-gonad-mesonephros (AGM) region, fetal liver (FL), and subsequently, the fetal bone marrow. In this study, we investigated the effects of primary stromal cells from fetal hematopoietic niches and their conditioned media (CM), applied singly or in sequential orders, on induction of human embryonic stem cells, H1, H9, and H14 lines, to hematopoietic cells. Our results demonstrated that stromal support of FL, AGM + FL, and AGM + FL + fetal bone marrow significantly increased the proliferation of embryoid bodies (EB) at day 18 of hematopoietic induction in the presence of thrombopoietin, stem cell factor, and Flt-3 ligand. AGM + FL also increased hematopoietic colony-forming unit (CFU) formation. CM did not enhance EB proliferation but CM of FL and AGM + FL significantly increased the density of total CFU and early erythroid (burst-forming unit) progenitors. Increased commitment to the hematopoietic lineage was demonstrated by enhanced expressions of CD45, alpha-, beta-, and gamma-globins in CFU at day 32, compared with EB at day 18. CM of FL significantly increased these globin expressions, indicating enhanced switches from embryonic to fetal and adult erythropoiesis. Over 50% and 10% of cells derived from CFU expressed CD45 and beta-globin proteins, respectively. Expressions of hematopoietic regulatory genes (Bmi-1, β-Catenin, Hox B4, GATA-1) were increased in EB or CFU cultures supported by FL or sequential CM. Our study has provided a strategy for derivation of hematopoietic cells from embryonic stem cells under the influence of primary hematopoietic niches and CM, particularly the FL.
- Published
- 2011
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31. Luxatio erecta complicated by anterior shoulder dislocation during reduction.
- Author
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Lam AC and Shih RD
- Abstract
Luxatio erecta humeri is an uncommon form of glenohumeral dislocation, resulting in the inferior displacement of the humeral head. Treatment with traction-counter traction techniques is usually successful in reducing most cases. We describe an unusual complication of this condition where initial reduction attempts of a luxatio erecta humeri repositioned the shoulder to an anterior dislocation position. After a thorough search of the literature, we were unable to find a similar case report of this type of complication during the reduction of a luxatio erecta shoulder dislocation.
- Published
- 2010
32. Subtelomeric 1q deletion syndrome causing patella hypoplasia and limb deformities, features overlapping with genitopatellar syndrome.
- Author
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Lam AC, Lai KK, Chau AT, Lo IF, and Lam ST
- Subjects
- Adolescent, Child, Child, Preschool, Humans, In Situ Hybridization, Fluorescence, Infant, Newborn, Karyotyping, Limb Deformities, Congenital diagnostic imaging, Male, Nucleic Acid Amplification Techniques, Patella diagnostic imaging, Patella pathology, Radiography, Syndrome, Chromosome Deletion, Chromosomes, Human, Pair 1 genetics, Limb Deformities, Congenital complications, Limb Deformities, Congenital genetics, Patella abnormalities, Telomere genetics
- Published
- 2009
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33. A combined strategy for quantitative trait loci detection by genome-wide association.
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Lam AC, Powell J, Wei WH, de Koning DJ, and Haley CS
- Abstract
Background: We applied a range of genome-wide association (GWA) methods to map quantitative trait loci (QTL) in the simulated dataset provided by the 12th QTLMAS workshop in order to derive an effective strategy., Results: A variance component linkage analysis revealed QTLs but with low resolution. Three single-marker based GWA methods were then applied: Transmission Disequilibrium Test and single marker regression, fitting an additive model or a genotype model, on phenotypes pre-corrected for pedigree and fixed effects. These methods detected QTL positions with high concordance to each other and with greater refinement of the linkage signals. Further multiple-marker and haplotype analyses confirmed the results with higher significance. Two-locus interaction analysis detected two epistatic pairs of markers that were not significant by marginal effects. Overall, using stringent Bonferroni thresholds we identified 9 additive QTL and 2 epistatic interactions, which together explained about 12.3% of the corrected phenotypic variance., Conclusion: The combination of methods that are robust against population stratification, like QTDT, with flexible linear models that take account of the family structure provided consistent results. Extensive simulations are still required to determine appropriate thresholds for more advanced model including epistasis.
- Published
- 2009
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34. Optimal design of genetic studies of gene expression with two-color microarrays in outbred crosses.
- Author
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Lam AC, Fu J, Jansen RC, Haley CS, and de Koning DJ
- Subjects
- Animals, Chromosome Mapping, Color, Computer Simulation, Crosses, Genetic, Gene Expression, Fluorescent Dyes, Gene Expression Profiling, Oligonucleotide Array Sequence Analysis methods, Quantitative Trait Loci, Research Design
- Abstract
Combining global gene-expression profiling and genetic analysis of natural allelic variation (genetical genomics) has great potential in dissecting the genetic pathways underlying complex phenotypes. Efficient use of microarrays is paramount in experimental design as the cost of conducting this type of study is high. For those organisms where recombinant inbred lines are available for mapping, the "distant pair design" maximizes the number of informative contrasts over all marker loci. Here, we describe an extension of this design, named the "optimal pair design," for use with F2 crosses between outbred lines. The performance of this design is investigated by simulation and compared to several other two-color microarray designs. We show that, for a given number of microarrays, the optimal pair design outperforms all other designs considered for detection of expression quantitative trait loci (eQTL) with additive effects by linkage analysis. We also discuss the suitability of this design for outbred crosses in organisms with large genomes and for detection of dominance.
- Published
- 2008
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35. Catamenial sciatica.
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Nevin Lam AC, Singh SS, and Leyland NA
- Subjects
- Adult, Dysmenorrhea etiology, Endometriosis diagnosis, Endometriosis surgery, Female, Humans, Laparoscopy, Laser Therapy, Sciatica surgery, Endometriosis complications, Sciatica etiology
- Published
- 2008
- Full Text
- View/download PDF
36. Isolated tumor cells and circulating CK20 mRNA in pN0 colorectal cancer patients.
- Author
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Wong CS, Cheung MT, Ma BB, Pun Hui E, Chan AC, Chan CK, Lee KC, Cheuk W, Lam MY, Wong MC, Chan CM, Chan JK, and Chan AT
- Subjects
- Adenocarcinoma secondary, Adult, Aged, Aged, 80 and over, Biomarkers, Tumor metabolism, Cell Count, Colorectal Neoplasms pathology, Female, Humans, Immunohistochemistry, Keratin-20 genetics, Keratin-20 metabolism, Lymph Nodes metabolism, Lymph Nodes pathology, Lymphatic Metastasis, Male, Middle Aged, RNA, Neoplasm analysis, Adenocarcinoma genetics, Biomarkers, Tumor genetics, Colorectal Neoplasms genetics, Neoplastic Cells, Circulating metabolism, RNA, Messenger analysis
- Abstract
Micrometastases in lymph nodes and blood may provide important prognostic information. In this study, cytokeratin 20 (CK20) positive cells in lymph nodes and circulating CK20 mRNA were studied using 57 paraffin-embedded lymph node specimens and blood from 24 patients with pN0 colorectal cancer (CRC), respectively. Results showed that 29 out of 56 (52%) lymph node specimens had CK20-positive cells (range: 1-35). Follow-up of the patients for 12 months indicated that 4 patients (7%) had CRC metastases to liver, lung, and bone. In addition, 8 out of 24 (33%) samples had at least 2-fold circulating CK20 mRNA expression higher than the pooled normal sample. This study provides evidence that CK20-positive cells were found in the lymph nodes and differentially expressed circulating CK20 mRNA was also detected in the blood from patients with pN0 CRC. Long-term follow-up is necessary to study their prognostic use in patients with non-metastatic CRC.
- Published
- 2008
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37. The plant mannose-binding lectin NTL preserves cord blood haematopoietic stem/progenitor cells in long-term culture and enhances their ex vivo expansion.
- Author
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Li K, Ooi VE, Chuen CK, Lam AC, Ooi LS, Zhang XB, Tsang KS, Chiu LC, Chan KY, Li CK, Fok TF, Yuen PM, and Ng PC
- Subjects
- Animals, Antigens, CD34, Cell Culture Techniques, Cell Proliferation, Culture Media, Serum-Free, Fetal Blood cytology, Graft Survival, Humans, Mice, Mice, Inbred NOD, Mice, SCID, Plant Leaves, Blood Preservation methods, Fetal Blood drug effects, Hematopoietic Stem Cells drug effects, Mannose-Binding Lectin pharmacology, Plant Lectins pharmacology
- Abstract
Ex vivo expansion of haematopoietic stem and progenitor cells in cytokine combinations is effective in promoting differentiation and proliferation of multilineage progenitor cells, but often results in reduction of self-renewable stem cells. This study investigated the effect of a mannose-binding lectin, NTL, purified from Narcissus tazetta var. chinensis, on prolonged maintenance and expansion of cord blood CD34+ cells. Our results showed that the presence of NTL or Flt-3 ligand (FL) significantly preserved a population of early stem/progenitor cells in a serum- and cytokine-free culture for 35 d. The effect of NTL on the ex vivo expansion of CD34+ cells in the presence of stem cell factor, thrombopoietin (TPO) and FL was also investigated. NTL-enhanced expansion of early progenitors (CD34+, CD34+CD38-, mixed colony-forming units and CFU-GEMM) and committed progenitor cells (granulocyte CFU, erythroid burst-forming units/CFU and megakayocyte CFU) after 8 and 12 d of culture. Six weeks after transplanting 12 d-expanded cells to non-obese diabetic severe combined immunodeficient mice, increased engraftment of human CD45+ cells was observed in the bone marrow of animals that received NTL-treated cells. The dual functions of NTL on long-term preservation and expansion of early stem/multilineage progenitor cells could be developed for applications in various cell therapy strategies, such as the clinical expansion of CD34+ cells for transplantation.
- Published
- 2008
- Full Text
- View/download PDF
38. Epstein-Barr virus associated leiomyosarcoma in a patient with systemic lupus erythematosus.
- Author
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Chan AC, Li CS, Cheuk W, and Chan JK
- Subjects
- Adult, Female, Herpesvirus 4, Human, Humans, Immunohistochemistry, Immunosuppressive Agents therapeutic use, Leiomyosarcoma pathology, Lupus Erythematosus, Systemic drug therapy, Abdominal Wall pathology, Epstein-Barr Virus Infections immunology, Immunocompromised Host, Leiomyosarcoma immunology, Lupus Erythematosus, Systemic complications, Tumor Virus Infections immunology
- Published
- 2007
- Full Text
- View/download PDF
39. Dedifferentiated chordoma with rhabdomyoblastic differentiation.
- Author
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Chan AC, Tsang WY, Chan GP, Lam YL, and Chan MK
- Subjects
- Aged, Bone Neoplasms metabolism, Bone Neoplasms surgery, Chordoma metabolism, Chordoma surgery, Humans, Immunohistochemistry, Magnetic Resonance Imaging, Male, Sacrum surgery, Tomography, X-Ray Computed, Bone Neoplasms pathology, Chordoma pathology, Sacrum pathology
- Published
- 2007
- Full Text
- View/download PDF
40. Interaction analysis of the CBLB and CTLA4 genes in type 1 diabetes.
- Author
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Payne F, Cooper JD, Walker NM, Lam AC, Smink LJ, Nutland S, Stevens HE, Hutchings J, and Todd JA
- Subjects
- Animals, CTLA-4 Antigen, Case-Control Studies, Denmark, Gene Frequency, Genetic Predisposition to Disease, Genetic Testing, Humans, Polymorphism, Single Nucleotide genetics, Rats, Adaptor Proteins, Signal Transducing genetics, Antigens, CD genetics, Antigens, Differentiation genetics, Diabetes Mellitus, Type 1 genetics, Proto-Oncogene Proteins c-cbl genetics
- Abstract
Gene-gene interaction analyses have been suggested as a potential strategy to help identify common disease susceptibility genes. Recently, evidence of a statistical interaction between polymorphisms in two negative immunoregulatory genes, CBLB and CTLA4, has been reported in type 1 diabetes (T1D). This study, in 480 Danish families, reported an association between T1D and a synonymous coding SNP in exon 12 of the CBLB gene (rs3772534 G>A; minor allele frequency, MAF=0.24; derived relative risk, RR for G allele=1.78; P=0.046). Furthermore, evidence of a statistical interaction with the known T1D susceptibility-associated CTLA4 polymorphism rs3087243 (laboratory name CT60, G>A) was reported (P<0.0001), such that the CBLB SNP rs3772534 G allele was overtransmitted to offspring with the CTLA4 rs3087243 G/G genotype. We have, therefore, attempted to obtain additional support for this finding in both large family and case-control collections. In a primary analysis, no evidence for an association of the CBLB SNP rs3772534 with disease was found in either sample set (2162 parent-child trios, P=0.33; 3453 cases and 3655 controls, P=0.69). In the case-only statistical interaction analysis between rs3772534 and rs3087243, there was also no support for an effect (1994 T1D affected offspring, and 3215 cases, P=0.92). These data highlight the need for large, well-characterized populations, offering the possibility of obtaining additional support for initial observations owing to the low prior probability of identifying reproducible evidence of gene-gene interactions in the analysis of common disease-associated variants in human populations.
- Published
- 2007
- Full Text
- View/download PDF
41. Multiple testing in the genomics era: findings from Genetic Analysis Workshop 15, Group 15.
- Author
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Martin LJ, Woo JG, Avery CL, Chen HS, North KE, Au K, Broët P, Dalmasso C, Guedj M, Holmans P, Huang B, Kuo PH, Lam AC, Li H, Manning A, Nikolov I, Sinha R, Shi J, Song K, Tabangin M, Tang R, and Yamada R
- Subjects
- Gene Expression Profiling, Humans, Polymorphism, Single Nucleotide, Genetic Testing methods, Genome, Human
- Abstract
Recent advances in molecular technologies have resulted in the ability to screen hundreds of thousands of single nucleotide polymorphisms and tens of thousands of gene expression profiles. While these data have the potential to inform investigations into disease etiologies and advance medicine, the question of how to adequately control both type I and type II error rates remains. Genetic Analysis Workshop 15 datasets provided a unique opportunity for participants to evaluate multiple testing strategies applicable to microarray and single nucleotide polymorphism data. The Genetic Analysis Workshop 15 multiple testing and false discovery rate group (Group 15) investigated three general categories for multiple testing corrections, which are summarized in this review: statistical independence, error rate adjustment, and data reduction. We show that while each approach may have certain advantages, adequate error control is largely dependent upon the question under consideration and often requires the use of multiple analytic strategies., ((c) 2007 Wiley-Liss, Inc.)
- Published
- 2007
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- View/download PDF
42. Rapid and robust association mapping of expression quantitative trait loci.
- Author
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Lam AC, Schouten M, Aulchenko YS, Haley CS, and de Koning DJ
- Abstract
We applied a simple and efficient two-step method to analyze a family-based association study of gene expression quantitative trait loci (eQTL) in a mixed model framework. This two-step method produces very similar results to the full mixed model method, with our method being significantly faster than the full model. Using the Genetic Analysis Workshop 15 (GAW15) Problem 1 data, we demonstrated the value of data filtering for reducing the number of tests and controlling the number of false positives. Specifically, we showed that removing non-expressed genes by filtering on expression variability effectively reduced the number of tests by nearly 50%. Furthermore, we demonstrated that filtering on genotype counts substantially reduced spurious detection. Finally, we restricted our analysis to the markers and transcripts that were closely located. We found five times more signals in close proximity (cis-) to transcripts than in our genome-wide analysis. Our results suggest that careful pre-filtering and partitioning of data are crucial for controlling false positives and allowing detection of genuine effects in genetic analysis of gene expression.
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- 2007
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43. Metaphyseal chondrodysplasia McKusick type in a Chinese fetus, caused by novel compound heterozygosity 64T> A and 79G >T in RMRPgene.
- Author
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Lam AC, Chan DH, Tong TM, Tang MH, Lo SY, Lo IF, and Lam ST
- Subjects
- Abortion, Eugenic, Adult, Female, Heterozygote, Humans, Mutation, Pregnancy, Sequence Analysis, DNA, Endoribonucleases genetics, Osteochondrodysplasias genetics
- Abstract
We present the first confirmed case by molecular analysis of a metaphyseal chondrodysplasia, McKusick type, in a 22-week fetus. Two novel compound heterozygous mutations, 64T> A and 79G > T, were found in the highly conserved regions of the RMRP gene. Twenty-two heterozygous g.1018 T> C mutations, two homozygous g.1018 T> C mutations, two heterozygous insertion mutations g.799_g.800insC and one heterozygous insertion mutation g.849_g.850insT were found among 100 normal controls. Careful radiological examination of the fetus for skeletal dysplasia allowed definitive diagnosis, proper genetic counselling and future prenatal diagnosis.
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- 2006
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44. Discovery, linkage disequilibrium and association analyses of polymorphisms of the immune complement inhibitor, decay-accelerating factor gene (DAF/CD55) in type 1 diabetes.
- Author
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Taniguchi H, Lowe CE, Cooper JD, Smyth DJ, Bailey R, Nutland S, Healy BC, Lam AC, Burren O, Walker NM, Smink LJ, Wicker LS, and Todd JA
- Abstract
Background: Type 1 diabetes (T1D) is a common autoimmune disease resulting from T-cell mediated destruction of pancreatic beta cells. Decay accelerating factor (DAF, CD55), a glycosylphosphatidylinositol-anchored membrane protein, is a candidate for autoimmune disease susceptibility based on its role in restricting complement activation and evidence that DAF expression modulates the phenotype of mice models for autoimmune disease. In this study, we adopt a linkage disequilibrium (LD) mapping approach to test for an association between the DAF gene and T1D., Results: Initially, we used HapMap II genotype data to examine LD across the DAF region. Additional resequencing was required, identifying 16 novel polymorphisms. Combining both datasets, a LD mapping approach was adopted to test for association with T1D. Seven tag SNPs were selected and genotyped in case-control (3,523 cases and 3,817 controls) and family (725 families) collections., Conclusion: We obtained no evidence of association between T1D and the DAF region in two independent collections. In addition, we assessed the impact of using only HapMap II genotypes for the selection of tag SNPs and, based on this study, found that HapMap II genotypes may require additional SNP discovery for comprehensive LD mapping of some genes in common disease.
- Published
- 2006
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45. Analysis of polymorphisms in 16 genes in type 1 diabetes that have been associated with other immune-mediated diseases.
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Smyth DJ, Howson JM, Payne F, Maier LM, Bailey R, Holland K, Lowe CE, Cooper JD, Hulme JS, Vella A, Dahlman I, Lam AC, Nutland S, Walker NM, Twells RC, and Todd JA
- Subjects
- ADAM Proteins genetics, Case-Control Studies, Humans, Immune System Diseases genetics, Diabetes Mellitus, Type 1 genetics, Genetic Predisposition to Disease, Polymorphism, Single Nucleotide
- Abstract
Background: The identification of the HLA class II, insulin (INS), CTLA-4 and PTPN22 genes as determinants of type 1 diabetes (T1D) susceptibility indicates that fine tuning of the immune system is centrally involved in disease development. Some genes have been shown to affect several immune-mediated diseases. Therefore, we tested the hypothesis that alleles of susceptibility genes previously associated with other immune-mediated diseases might perturb immune homeostasis, and hence also associate with predisposition to T1D., Methods: We resequenced and genotyped tag single nucleotide polymorphisms (SNPs) from two genes, CRP and FCER1B, and genotyped 27 disease-associated polymorphisms from thirteen gene regions, namely FCRL3, CFH, SLC9A3R1, PADI4, RUNX1, SPINK5, IL1RN, IL1RA, CARD15, IBD5-locus (including SLC22A4), LAG3, ADAM33 and NFKB1. These genes have been associated previously with susceptibility to a range of immune-mediated diseases including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Graves' disease (GD), psoriasis, psoriatic arthritis (PA), atopy, asthma, Crohn disease and multiple sclerosis (MS). Our T1D collections are divided into three sample subsets, consisting of set 1 families (up to 754 families), set 2 families (up to 743 families), and a case-control collection (ranging from 1,500 to 4,400 cases and 1,500 to 4,600 controls). Each SNP was genotyped in one or more of these subsets. Our study typically had approximately 80% statistical power for a minor allele frequency (MAF) >5% and odds ratios (OR) of 1.5 with the type 1 error rate, alpha = 0.05., Results: We found no evidence of association with T1D at most of the loci studied 0.02
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- 2006
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46. High rate of detection of subtelomeric aberration by using combined MLPA and subtelomeric FISH approach in patients with moderate to severe mental retardation.
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Lam AC, Lam ST, Lai KK, Tong TM, and Chau TC
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- Child, Child, Preschool, Female, Gene Duplication, Heterozygote, Humans, Male, Patient Selection, Pedigree, Pilot Projects, Chromosome Deletion, In Situ Hybridization, Fluorescence, Intellectual Disability genetics, Molecular Probe Techniques, Telomere genetics
- Abstract
Objectives: (1) To evaluate the prevalence of subtelomeric deletion in moderate to severe mental retardation population, (2) to assess the feasibility and cost-effectiveness of combined methodology in routine workup of this sub-population., Method: Twenty unrelated patients using strict selection criteria were recruited for the study from the Clinical Genetic Service. Patients were initially screened by Multiplex Ligation-dependent Probe Amplification (MLPA) for subtelomeric imbalance followed by FISH analysis for anatomical integrity. This is then followed by parental subtelomeric FISH analysis., Results: Three subtelomeric deletions were identified. They were Deletion 1p36, Deletion 1q44 and Deletion 10q26; these were previously unidentified by conventional technique., Conclusions: The prevalence of subtelomeric deletion in our cohort of moderate to severe mental retardation patients is consistent with published findings of around 10%. The figure is on the higher side if more stringent criteria is used. The combination of strict clinical criteria, MLPA and selective subtelomeric FISH was shown to be feasible and cost-effective.
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- 2006
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47. Polymorphism discovery and association analyses of the interferon genes in type 1 diabetes.
- Author
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Morris GA, Lowe CE, Cooper JD, Payne F, Vella A, Godfrey L, Hulme JS, Walker NM, Healy BC, Lam AC, Lyons PA, and Todd JA
- Subjects
- Autoimmune Diseases genetics, Databases, Genetic, Exons, Family Health, Female, Genetic Linkage, Humans, Interferon Type I genetics, Interferon-alpha genetics, Interferon-beta genetics, Interferon-gamma genetics, Linkage Disequilibrium, Male, Models, Statistical, Multigene Family, Polymorphism, Single Nucleotide, Sequence Analysis, DNA, Diabetes Mellitus, Type 1 genetics, Genetic Predisposition to Disease, Interferons genetics, Polymorphism, Genetic
- Abstract
Background: The aetiology of the autoimmune disease type 1 diabetes (T1D) involves many genetic and environmental factors. Evidence suggests that innate immune responses, including the action of interferons, may also play a role in the initiation and/or pathogenic process of autoimmunity. In the present report, we have adopted a linkage disequilibrium (LD) mapping approach to test for an association between T1D and three regions encompassing 13 interferon alpha (IFNA) genes, interferon omega-1 (IFNW1), interferon beta-1 (IFNB1), interferon gamma (IFNG) and the interferon consensus-sequence binding protein 1 (ICSBP1)., Results: We identified 238 variants, most, single nucleotide polymorphisms (SNPs), by sequencing IFNA, IFNB1, IFNW1 and ICSBP1, 98 of which where novel when compared to dbSNP build 124. We used polymorphisms identified in the SeattleSNP database for INFG. A set of tag SNPs was selected for each of the interferon and interferon-related genes to test for an association between T1D and this complex gene family. A total of 45 tag SNPs were selected and genotyped in a collection of 472 multiplex families., Conclusion: We have developed informative sets of SNPs for the interferon and interferon related genes. No statistical evidence of a major association between T1D and any of the interferon and interferon related genes tested was found.
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- 2006
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48. Systemic autoimmune disease induced by dendritic cells that have captured necrotic but not apoptotic cells in susceptible mouse strains.
- Author
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Ma L, Chan KW, Trendell-Smith NJ, Wu A, Tian L, Lam AC, Chan AK, Lo CK, Chik S, Ko KH, To CK, Kam SK, Li XS, Yang CH, Leung SY, Ng MH, Stott DI, MacPherson GG, and Huang FP
- Subjects
- Animals, Antibodies, Antinuclear biosynthesis, Autoimmune Diseases pathology, Cytokines biosynthesis, Cytokines genetics, DNA immunology, Dendritic Cells metabolism, Dendritic Cells pathology, Disease Susceptibility immunology, Erythema immunology, Erythema pathology, Face, Female, Humans, Kidney immunology, Kidney pathology, Mice, Mice, Inbred C57BL, Mice, Inbred MRL lpr, Necrosis, Proteinuria immunology, Proteinuria pathology, Skin Ulcer immunology, Skin Ulcer pathology, Apoptosis immunology, Autoimmune Diseases immunology, Dendritic Cells immunology
- Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disorder of a largely unknown etiology. Anti-double-stranded (ds) DNA antibodies are a classic hallmark of the disease, although the mechanism underlying their induction remains unclear. We demonstrate here that, in both lupus-prone and normal mouse strains, strong anti-dsDNA antibody responses can be induced by dendritic cells (DC) that have ingested syngeneic necrotic (DC/nec), but not apoptotic (DC/apo), cells. Clinical manifestations of lupus were evident, however, only in susceptible mouse strains, which correlate with the ability of DC/nec to release IFN-gamma and to induce the pathogenic IgG2a anti-dsDNA antibodies. Injection of DC/nec not only accelerated disease progression in the MRL/MpJ-lpr/lpr lupus-prone mice but also induced a lupus-like disease in the MRL/MpJ-+/+ wild-type control strain. Immune complex deposition was readily detectable in the kidneys, and the mice developed proteinuria. Strikingly, female MRL/MpJ-+/+ mice that had received DC/nec, but not DC/apo, developed a 'butterfly' facial lesion resembling a cardinal feature of human SLE. Our study therefore demonstrates that DC/nec inducing a Th1 type of responses, which are otherwise tightly regulated in a normal immune system, may play a pivotal role in SLE pathogenesis.
- Published
- 2005
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49. Population structure, differential bias and genomic control in a large-scale, case-control association study.
- Author
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Clayton DG, Walker NM, Smyth DJ, Pask R, Cooper JD, Maier LM, Smink LJ, Lam AC, Ovington NR, Stevens HE, Nutland S, Howson JM, Faham M, Moorhead M, Jones HB, Falkowski M, Hardenbol P, Willis TD, and Todd JA
- Subjects
- Adolescent, Bias, Case-Control Studies, DNA blood, False Positive Reactions, Genotype, Humans, Lymphocytes metabolism, United Kingdom epidemiology, Diabetes Mellitus, Type 1 epidemiology, Diabetes Mellitus, Type 1 genetics, Genetics, Population, Models, Genetic, Polymorphism, Single Nucleotide genetics
- Abstract
The main problems in drawing causal inferences from epidemiological case-control studies are confounding by unmeasured extraneous factors, selection bias and differential misclassification of exposure. In genetics the first of these, in the form of population structure, has dominated recent debate. Population structure explained part of the significant +11.2% inflation of test statistics we observed in an analysis of 6,322 nonsynonymous SNPs in 816 cases of type 1 diabetes and 877 population-based controls from Great Britain. The remainder of the inflation resulted from differential bias in genotype scoring between case and control DNA samples, which originated from two laboratories, causing false-positive associations. To avoid excluding SNPs and losing valuable information, we extended the genomic control method by applying a variable downweighting to each SNP.
- Published
- 2005
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50. No evidence for association of the TATA-box binding protein glutamine repeat sequence or the flanking chromosome 6q27 region with type 1 diabetes.
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Payne F, Smyth DJ, Pask R, Cooper JD, Masters J, Wang WY, Godfrey LM, Bowden G, Szeszko J, Smink LJ, Lam AC, Burren O, Walker NM, Nutland S, Rance H, Undlien DE, Rønningen KS, Guja C, Ionescu-Tîrgovişte C, Todd JA, and Twells RC
- Subjects
- Genetic Predisposition to Disease genetics, Humans, Microsatellite Repeats genetics, Polymorphism, Genetic genetics, TATA-Box Binding Protein metabolism, Chromosomes, Human, Pair 6 genetics, DNA, Intergenic genetics, Diabetes Mellitus, Type 1 genetics, Glutamine genetics, Repetitive Sequences, Amino Acid genetics, TATA-Box Binding Protein chemistry, TATA-Box Binding Protein genetics
- Abstract
Susceptibility to the autoimmune disease type 1 diabetes has been linked to human chromosome 6q27 and, moreover, recently associated with one of the genes in the region, TATA box-binding protein (TBP). Using a much larger sample of T1D families than those studied by others, and by extensive re-sequencing of nine other genes in the proximity, in which we identified 279 polymorphisms, 83 of which were genotyped in up to 725 T1D multiplex and simplex families, we obtained no evidence for association of the TBP CAG/CAA (glutamine) microsatellite repeat sequence with disease, or for nine other genes, PDCD2, PSMB1, KIAA1838, DLL1, dJ894D12.4, FLJ25454, FLJ13162, FLJ11152, PHF10 and CCR6. This study also provides an exon-based tag single nucleotide polymorphism map for these 10 genes that can be used for analysis of other diseases.
- Published
- 2005
- Full Text
- View/download PDF
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