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Stöver T, Plontke SK, Lai WK, Zahnert T, Guntinas-Lichius O, Welkoborsky HJ, Aschendorff A, Deitmer T, Loth A, Lang S, Dazert S. The German cochlear implant registry: one year experience and first results on demographic data. Eur Arch Otorhinolaryngol 2024; 281:5243-5254. [PMID: 38977469 PMCID: PMC11416385 DOI: 10.1007/s00405-024-08775-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 06/03/2024] [Indexed: 07/10/2024]
Abstract
PURPOSE Clinical registries have great potential for quality control of medical procedures regarding the indications, therapeutic processes and results, including their possible complications. This is particularly true when providing patients with severe hearing loss or deafness with a cochlear implant (CI). This treatment represents a lifelong care process that requires continuous quality control over time. On the initiative of the Executive Committee of the German Society of Otorhinolaryngology (Deutsche Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e.V., DGHNO-KHC), a national German CI registry (Deutsches Cochlear Implant Register, DCIR) was established in January 2022. This article focuses on the first demographic and baseline data of the DCIR. METHODS The DCIR covers the complete therapeutic process from indication, surgery, fitting and lifelong aftercare in CI therapy. By the end of 2022, 75 hospitals in Germany had agreed to contribute to the DCIR. RESULTS During the year 2022, 63 hospitals actively contributed data to the DCIR. Pseudonymized data from 2,292 CI implantations (2,176 primary implantations, 99 explantations with immediate re-implantations and 17 re-implantations following an earlier explantation) in 2,108 patients were documented. Cochlear implantation was accomplished in 1,807 adults (≥ 18 years) and 301 children (< 18 years). Fourty patients (1,9%) were children < 1 year of age and 55 (2,6%) were patients > 85 years. From the total of 2,292 implantations, 226 (9.9%) were performed as simultaneous bilateral implantations (CI implantation in both ears of 113 patients on the same day of surgery) and 412 implantations (19.1% of 2,162 implantations with data provided on the contralateral ear's hearing status) were in patients with single sided deafness (normal hearing in the contralateral ear). In addition, the reported complications in 2022 were also evaluated. Seven reports (0.4%) of mild to moderate severe facial nerve dysfunctions were documented. No reports of severe or total facial nerve dysfunction (House-Brackmann grade V/VI), meningitis or death related to CI therapy were documented. CONCLUSION Although still in the start-up phase, these initial DCIR data already provide an interesting first insight into the demographic structure and baseline data of CI therapy in Germany. The successful implementation of the DCIR represents an important step towards continuous quality control of CI care.
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O'Leary S, Mylanus E, Venail F, Lenarz T, Birman C, Di Lella F, Roland JT, Gantz B, Beynon A, Sicard M, Buechner A, Lai WK, Boccio C, Choudhury B, Tejani VD, Plant K, English R, Arts R, Bester C. Monitoring Cochlear Health With Intracochlear Electrocochleography During Cochlear Implantation: Findings From an International Clinical Investigation. Ear Hear 2023; 44:358-370. [PMID: 36395515 PMCID: PMC9957964 DOI: 10.1097/aud.0000000000001288] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVES Electrocochleography (ECochG) is emerging as a tool for monitoring cochlear function during cochlear implant (CI) surgery. ECochG may be recorded directly from electrodes on the implant array intraoperatively. For low-frequency stimulation, its amplitude tends to rise or may plateau as the electrode is inserted. The aim of this study was to explore whether compromise of the ECochG signal, defined as a fall in its amplitude of 30% or more during insertion, whether transient or permanent, is associated with poorer postoperative acoustic hearing, and to examine how preoperative hearing levels may influence the ability to record ECochG. The specific hypotheses tested were threefold: (a) deterioration in the pure-tone average of low-frequency hearing at the first postoperative follow-up interval (follow-up visit 1 [FUV1], 4 to 6 weeks) will be associated with compromise of the cochlear microphonic (CM) amplitude during electrode insertion (primary hypothesis); (b) an association is observed at the second postoperative follow-up interval (FUV2, 3 months) (secondary hypothesis 1); and (c) the CM response will be recorded earlier during electrode array insertion when the preoperative high-frequency hearing is better (secondary hypothesis 2). DESIGN International, multi-site prospective, observational, between groups design, targeting 41 adult participants in each of two groups, (compromised CM versus preserved CM). Adult CI candidates who were scheduled to receive a Cochlear Nucleus CI with a Slim Straight or a Slim Modiolar electrode array and had a preoperative audiometric low-frequency average thresholds of ≤80 dB HL at 500, 750, and 1000 Hz in the ear to be implanted, were recruited from eight international implant sites. Pure tone audiometry was measured preoperatively and at postoperative visits (FUV1 and follow-up visit 2 [FUV2]). ECochG was measured during and immediately after the implantation of the array. RESULTS From a total of 78 enrolled individuals (80 ears), 77 participants (79 ears) underwent surgery. Due to protocol deviations, 18 ears (23%) were excluded. Of the 61 ears with ECochG responses, amplitudes were < 1 µV throughout implantation for 18 ears (23%) and deemed "unclear" for classification. EcochG responses >1 µV in 43 ears (55%) were stable throughout implantation for 8 ears and compromised in 35 ears. For the primary endpoint at FUV1, 7/41 ears (17%) with preserved CM had a median hearing loss of 12.6 dB versus 34/41 ears (83%) with compromised CM and a median hearing loss of 26.9 dB ( p < 0.014). In assessing the practicalities of measuring intraoperative ECochG, the presence of a measurable CM (>1 µV) during implantation was dependent on preoperative, low-frequency thresholds, particularly at the stimulus frequency (0.5 kHz). High-frequency, preoperative thresholds were also associated with a measurable CM > 1 µV during surgery. CONCLUSIONS Our data shows that CM drops occurring during electrode insertion were correlated with significantly poorer hearing preservation postoperatively compared to CMs that remained stable throughout the electrode insertion. The practicality of measuring ECochG in a large cohort is discussed, regarding the suggested optimal preoperative low-frequency hearing levels ( < 80 dB HL) considered necessary to obtain a CM signal >1 µV.
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Lai WK, Dillier N, Weber BP, Lenarz T, Battmer R, Gantz B, Brown C, Cohen N, Waltzman S, Skinner M, Holden L, Cowan R, Busby P, Killian M. TNRT profiles with the nucleus research platform 8 system. Int J Audiol 2010; 48:645-54. [PMID: 19513917 DOI: 10.1080/14992020902962413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
This study investigates the effect of the Nucleus CI24RE implant's neural response telemetry (NRT) system, which has less internal noise compared to its predecessor, the CI24M/R implant, on the NRT threshold (TNRT) profile across the array. CI24M/R measurements were simulated by ignoring CI24RE measurements with response amplitudes below 50 uV. Comparisons of the estimated TNRTs from the CI24RE measurements and the CI24M/R simulations suggest that, apart from a constant level difference, the TNRT profiles from the newer implant generally would not have differed very much from those of its predecessor. This view was also reflected by principal component analysis (PCA) results which revealed a 'shift' component similar to that reported by Smoorenburg et al (2002). On the whole, there is no indication that current practices of using the TNRT profiles for assisting with speech processor programming need to be revised for the CI24RE implant.
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Lo R, Lai WK. Medical image. An unusual cause of left iliac fossa mass. THE NEW ZEALAND MEDICAL JOURNAL 2008; 121:74-75. [PMID: 18815608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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Alabraba EB, Curbishley SM, Lai WK, Wigmore SJ, Adams DH, Afford SC. A new approach to isolation and culture of human Kupffer cells. J Immunol Methods 2007; 326:139-44. [PMID: 17692868 DOI: 10.1016/j.jim.2007.06.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Accepted: 06/22/2007] [Indexed: 11/18/2022]
Abstract
Macrophages are a diverse population of cells that are able to adapt to specific tissue environments. Kupffer cells are liver resident macrophages and form the largest population of fixed tissue macrophages. Their isolation offers an exciting opportunity to study this subpopulation of uniquely adapted cells. However existing Kupffer cell isolation techniques are tedious and are still largely based on enzymatic digestion to liberate tissue macrophages from the closely associated surrounding tissue. Isolation techniques have continually evolved over the last 3 decades but are neither easily applicable nor user friendly. This is highlighted by a review of current literature which will show that there is a scarcity of published studies employing human Kupffer cells. The other difficulty with Kupffer cells and some other populations of macrophages in culture is the strong tenacity with which they adhere to solid substrate and their resistance to conventional sub-culture dissociation agents. The difficulty with cell dissociation has previously required cells to be grown in suspension culture. This has been achieved by culturing macrophages in Teflon bags but unfortunately this deprives cells of the maturation signals generated by adherence. In this article we have upped the ante by describing a 'user friendly' method for Kupffer cell isolation and new culture techniques that allow Kupffer cells to be grown in adherency whilst at the same time circumventing the difficulties posed by the adherence of these unique cells.
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Thurairajah PH, Thorburn D, Hubscher S, White A, Lai WK, O'Donnell K, Mutimer D. Incidence and characterization of serum transaminases elevations in pegylated interferon and ribavirin treated patients with chronic hepatitis C. Aliment Pharmacol Ther 2007; 25:1293-300. [PMID: 17509097 DOI: 10.1111/j.1365-2036.2007.03322.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND A virological response to pegylated-interferon and ribavirin is typically associated with a prompt fall in serum transaminases. For some patients, transaminases rise during treatment. AIM To assess the frequency and define factors associated with elevations of serum transaminases. METHODS A total of 169 treated patients were studied. Transaminase elevations were graded by WHO criteria - grade 0: no value > baseline, grade 1: 1-2x baseline, grade 2: 2.1-5x baseline, grade 3: >5x, grade 4: any rise with evidence of liver failure. Results 60/169 (35%) patients experienced transaminase elevations: 52 grade 1, 6 grade 2, 1 grade 3, 1 grade 4. Overall, end of treatment response and sustained virological response rates were 72% and 55%. Lower rates were observed in the grade 1 elevation group (63% and 40%) compared with patients with grade 0 (79% and 65%) and grade > or =2 elevations (85% and 71%). Grade 1 elevations tended to occur earlier during treatment than grade > or =2 elevations. Transaminase elevations were associated with greater pre-treatment body weight (P = 0.006), steatosis (P = 0.008) and poorer sustained virological response rates (P = 0.007). CONCLUSIONS Transaminase elevations during treatment of chronic Hepatitis C virus with pegylated interferon and ribavirin are common but rarely severe. Mild rises may reflect ongoing viral activity in treatment non-responders. More significant rises are frequently observed despite a virological response, and may be because of an immuno-modulating effect of interferon in susceptible patients.
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Weber BP, Lai WK, Dillier N, von Wallenberg EL, Killian MJP, Pesch J, Battmer RD, Lenarz T. Performance and Preference for ACE Stimulation Rates Obtained with Nucleus RP 8 and Freedom System. Ear Hear 2007; 28:46S-48S. [PMID: 17496645 DOI: 10.1097/aud.0b013e3180315442] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Cochlear recently released the Nucleus Freedom System which has been based on the Nucleus Research Platform 8. Both systems make use of the same implant, the CI24RE, which includes expanded total stimulation rates up to 32 kHz. In this study the performance of the ACE strategy at 500, 1200 and 3500 pps/channel was investigated using an ABC-CBA design. At the end of each period speech tests were performed. In the CBA phase the patients completed a comparative questionnaire to determine the subjective rate preference. Preliminary results in 13 recipients indicate no differences in for the ACE strategy at rates ranging from 500 pps to 3500 pps/channel.
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Lalor PF, Lai WK, Curbishley SM, Shetty S, Adams DH. Human hepatic sinusoidal endothelial cells can be distinguished by expression of phenotypic markers related to their specialised functions in vivo. World J Gastroenterol 2006; 12:5429-39. [PMID: 17006978 PMCID: PMC4088223 DOI: 10.3748/wjg.v12.i34.5429] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The hepatic sinusoids are lined by a unique population of hepatic sinusoidal endothelial cells (HSEC), which is one of the first hepatic cell populations to come into contact with blood components. However, HSEC are not simply barrier cells that restrict the access of blood-borne compounds to the parenchyma. They are functionally specialised endothelial cells that have complex roles, including not only receptor-mediated clearance of endotoxin, bacteria and other compounds, but also the regulation of inflammation, leukocyte recruitment and host immune responses to pathogens. Thus understanding the differentiation and function of HSEC is critical for the elucidation of liver biology and pathophysiology. This article reviews methods for isolating and studying human hepatic endothelial cell populations using in vitro models. We also discuss the expression and functions of phenotypic markers, such as the presence of fenestrations and expression of VAP-1, Stabilin-1, L-SIGN, which can be used to identify sinusoidal endothelium and to permit discrimination from vascular and lymphatic endothelial cells.
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MESH Headings
- Amine Oxidase (Copper-Containing)/genetics
- Amine Oxidase (Copper-Containing)/metabolism
- Biomarkers/metabolism
- Cell Adhesion Molecules/genetics
- Cell Adhesion Molecules/metabolism
- Cell Adhesion Molecules, Neuronal/genetics
- Cell Adhesion Molecules, Neuronal/metabolism
- Cells, Cultured
- Endothelial Cells/metabolism
- Endothelium, Lymphatic/cytology
- Endothelium, Vascular/cytology
- Gene Expression Regulation/genetics
- Humans
- Lectins, C-Type/genetics
- Lectins, C-Type/metabolism
- Liver/blood supply
- Liver/cytology
- Liver/metabolism
- Liver Circulation
- Phenotype
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Lymphocyte Homing/genetics
- Receptors, Lymphocyte Homing/metabolism
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Lai WK, Sun PJ, Zhang J, Jennings A, Lalor PF, Hubscher S, McKeating JA, Adams DH. Expression of DC-SIGN and DC-SIGNR on human sinusoidal endothelium: a role for capturing hepatitis C virus particles. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 169:200-8. [PMID: 16816373 PMCID: PMC1698775 DOI: 10.2353/ajpath.2006.051191] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hepatic sinusoidal endothelial cells are unique among endothelial cells in their ability to internalize and process a diverse range of antigens. DC-SIGNR, a type 2 C-type lectin expressed on liver sinusoids, has been shown to bind with high affinity to hepatitis C virus (HCV) E2 glycoprotein. DC-SIGN is a closely related homologue reported to be expressed only on dendritic cells and a subset of macrophages and has similar binding affinity to HCV E2 glycoprotein. These receptors function as adhesion and antigen presentation molecules. We report distinct patterns of DC-SIGNR and DC-SIGN expression in human liver tissue and show for the first time that both C-type lectins are expressed on sinusoidal endothelial cells. We confirmed that these receptors are functional by demonstrating their ability to bind HCV E2 glycoproteins. Although these lectins on primary sinusoidal cells support HCV E2 binding, they are unable to support HCV entry. These data support a model where DC-SIGN and DC-SIGNR on sinusoidal endothelium provide a mechanism for high affinity binding of circulating HCV within the liver sinusoids allowing subsequent transfer of the virus to underlying hepatocytes, in a manner analogous to DC-SIGN presentation of human immunodeficiency virus on dendritic cells.
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Shah T, Lai WK, Gow P, Leeming J, Mutimer D. Low-dose amphotericin for prevention of serious fungal infection following liver transplantation. Transpl Infect Dis 2005; 7:126-32. [PMID: 16390401 DOI: 10.1111/j.1399-3062.2005.00108.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS This study advances previously performed clinical studies of antifungal prophylaxis and prospectively evaluates the efficacy of low-dose amphotericin B preparations for the prevention of invasive fungal infection (IFI) in high-risk liver transplant (LT) recipients. METHODS High-risk LT patients were recruited and randomised to openly receive intravenously either conventional amphotericin B (amB) at a dose of 15 mg daily, or liposomal amphotericin B (amBisome) 50 mg daily. Prophylaxis was continued until discharge from the intensive care unit (ICU), until patient death, or until time of conversion to high-dose amBisome for treatment of suspected or confirmed IFI. RESULTS During the study period, 360 adult LTs were performed; 132 patients were eligible for 149 recruitment episodes into the trial, and 83 patients were recruited for 92 episodes. Of the 92, 48 patient episodes were randomised to receive amBisome prophylaxis, and 44 to receive amB. IFI was uncommon, diagnosed for 3 patients in the amBisome group, and for 2 in the amB group. Furthermore, Aspergillus was isolated on a single occasion during 92 episodes of prophylaxis. Fungal colonisation scores did not differ significantly between the 2 groups. There was a significant difference in the rates of survival to ICU discharge between the 2 groups (79.6% amBisome vs. 59.5% amB, P=0.038). Renal function measures including creatinine clearance at commencement and conclusion of prophylaxis, and at 12 months post transplant were not statistically different between the 2 groups. CONCLUSION The use of amphotericin B, liposomal or non-liposomal preparations at low doses, for prophylaxis of IFI in high-risk LT patients, is associated with a low incidence of serious fungal infection. In this randomised study, low-dose amBisome prophylaxis was associated with an increased likelihood of successful discharge from the ICU.
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Shah T, Lai WK, Mutimer D. Impact of targeted oral ganciclovir prophylaxis for transplant recipients of livers from cytomegalovirus-seropositive donors. Transpl Infect Dis 2005; 7:57-62. [PMID: 16150091 DOI: 10.1111/j.1399-3062.2005.00093.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Symptomatic cytomegalovirus (CMV) infection can cause significant morbidity and occasional mortality after liver transplantation. In a previous audit, we showed that donor CMV seropositivity (D+) was a risk factor for symptomatic infection, and we estimated the likely clinical and financial impact of 14 weeks of oral ganciclovir prophylaxis given to recipients of CMV-seropositive organs. In August 2001, we adopted this policy of targeted oral ganciclovir prophylaxis for recipients of CMV-seropositive livers. METHOD The additional costs of adopting targeted prophylaxis policy for 1 year, patient and doctor compliance with the new strategy, and its clinical impact were analysed. RESULTS Targeted prophylaxis reduced the incidence of symptomatic CMV infection from 9.5% (in the earlier cohort that did not receive prophylaxis) to 5.8% (P = NS). Symptomatic infection was not observed in CMV-seropositive recipients of CMV-seropositive donor livers (P = 0.06 for comparison of the 2 cohorts), but the incidence of symptomatic infection in the CMV-seronegative recipients of CMV-seropositive organs did not change. However, symptomatic infection appeared to be less severe and was delayed by ganciclovir prophylaxis (median time from transplantation to symptom onset 96 vs. 39 days without prophylaxis). Death attributable to CMV infection was not observed in the cohort that received prophylaxis. The additional cost associated with implementation of the prophylaxis strategy was 108,068 pounds sterlings. CONCLUSION Targeted CMV prophylaxis with oral ganciclovir reduces the incidence and severity of symptomatic infection and appears to be a cost-effective means of improving outcome following liver transplantation.
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Cafarelli Dees D, Dillier N, Lai WK, von Wallenberg E, van Dijk B, Akdas F, Aksit M, Batman C, Beynon A, Burdo S, Chanal JM, Collet L, Conway M, Coudert C, Craddock L, Cullington H, Deggouj N, Fraysse B, Grabel S, Kiefer J, Kiss JG, Lenarz T, Mair A, Maune S, Müller-Deile J, Piron JP, Razza S, Tasche C, Thai-Van H, Toth F, Truy E, Uziel A, Smoorenburg GF. Normative findings of electrically evoked compound action potential measurements using the neural response telemetry of the Nucleus CI24M cochlear implant system. Audiol Neurootol 2005; 10:105-16. [PMID: 15650302 DOI: 10.1159/000083366] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Accepted: 09/06/2004] [Indexed: 11/19/2022] Open
Abstract
One hundred and forty-seven adult recipients of the Nucleus 24 cochlear implant system, from 13 different European countries, were tested using neural response telemetry to measure the electrically evoked compound action potential (ECAP), according to a standardised postoperative measurement procedure. Recordings were obtained in 96% of these subjects with this standardised procedure. The group results are presented in terms of peak amplitude and latency, slope of the amplitude growth function and ECAP threshold. The effects of aetiological factors and the duration of deafness on the ECAP were also studied. While large intersubject variability and intrasubject variability (across electrodes) were found, results fell within a consistent pattern and a normative range of peak amplitudes and latencies was established. The aetiological factors had little effect on the ECAP characteristics. However, age affected ECAP amplitude and slope of the amplitude growth function significantly; i.e., the amplitude is higher in the lowest age category (15-30 years). Principal component analysis of the ECAP thresholds shows that the thresholds across 5 electrodes can be described by two factors accounting for 92% of the total variance. The two factors represent the overall level of the threshold profiles ('shift') and their slopes across the electrode array ('tilt'). Correlation between these two factors and the same factors describing the T- and C-levels appeared to be moderate, in the range of 0.5-0.6.
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Lai WK, Adams DH. Angiogenesis and chronic inflammation; the potential for novel therapeutic approaches in chronic liver disease. J Hepatol 2005; 42:7-11. [PMID: 15629498 DOI: 10.1016/j.jhep.2004.11.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Battmer RD, Dillier N, Lai WK, Weber BP, Brown C, Gantz BJ, Roland JT, Cohen NJ, Shapiro W, Pesch J, Killian MJ, Lenarz T. Evaluation of the neural response telemetry (NRT) capabilities of the nucleus research platform 8: initial results from the NRT trial. Int J Audiol 2004; 43 Suppl 1:S10-5. [PMID: 15732376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The purpose of this study was to evaluate the performance of the new features of the Nucleus Research Platform 8 (RP8), a system developed specifically for research purposes The RP8 consists of a research implant, a speech processor and a new NRT software (NRT v4), and includes comparisons of the different artefact-cancellation methods, NRT threshold, and recovery function measurements. The system has new artefact-suppression techniques and new diagnostic capabilities; their performance has been verified in animal experiments. In this study, NRT data were collected from 15 postlingually deafened adult cochlear implant patients intraoperatively and up to 6 months postoperatively after switch-on. The initial investigation in two clinics in Europe focused primarily on the enhanced NRT capabilities Results from the trial in two European clinics indicate that NRT measurements can be obtained with lower noise levels. A comparison of the different artefact-cancellation techniques showed that the forward-masking paradigm implemented in the Nucleus 3 system is still the method of choice. The focus of this report is on recovery function characteristics, which may give insight into auditory nerve fiber properties with regard to higher stimulation rates.
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Kwok T, Cheng G, Lai WK, Poon P, Woo J, Pang CP. Use of fasting urinary methylmalonic acid to screen for metabolic vitamin B12 deficiency in older persons. Nutrition 2004; 20:764-8. [PMID: 15325684 DOI: 10.1016/j.nut.2004.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVES We sought to determine the cutoffs of fasting urinary methylmalonic acid (MMA) indicating elevated and mildly elevated serum MMA concentrations in older persons. METHODS We studied 113 female Chinese vegetarians older than 55 y with normal renal function. Fasting serum samples were obtained for measurement of vitamin B12, MMA, and folate and tests of renal function. A fasting urine sample was collected for MMA measurement by the stable-isotope dilution method. The correlation between serum and urinary MMA levels was examined. The optimal cutoffs of urinary MMA for predicting elevated and mildly elevated serum MMA were estimated by use of receiver operating characteristic curves. RESULTS Fasting urinary and serum MMA levels were linearly correlated. Pearson's correlation coefficient was 0.94. The cutoff of fasting urinary MMA of 2 microM/mM of creatinine had a sensitivity of 79%, a specificity of 85%, and a positive predictive value of 93% for elevated serum MMA (> 0.4 microM/L). A cutoff of 1.5 microM/mM of creatinine had a sensitivity of 86%, a specificity of 85%, and a positive predictive value of 95% for mildly elevated serum MMA (> 0.3 microM/L). Both cutoffs had high positive predictive values for subnormal vitamin B12 concentrations. CONCLUSION Overnight fasting urinary MMA concentrations have a strong linear relation to serum MMA in older vegetarians without renal impairment. Urinary MMA is potentially useful as a screening tool for metabolic vitamin B12 deficiency in older persons.
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Weber BP, Strauchmann B, Lai WK, Altermatt S. Cochlea- und Hirnstammimplantate in Interaktion mit CSF-Shunts. Laryngorhinootologie 2004. [DOI: 10.1055/s-2004-823243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Kwok T, Cheng G, Woo J, Lai WK, Pang CP. Independent effect of vitamin B12 deficiency on hematological status in older Chinese vegetarian women. Am J Hematol 2002; 70:186-90. [PMID: 12111763 DOI: 10.1002/ajh.10134] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have examined the independent effect of vitamin B(12) deficiency on hematological indices in older Chinese vegetarian women using a cross-sectional study design: 119 women older than 55 years who had been vegetarian for more than 3 years were studied. Fasting blood samples were taken for complete blood count, serum iron, total serum iron binding capacity, serum iron saturation, serum vitamin B(12), serum folate, serum methylmalonic acid levels (MMA), and renal function test. Subjects with iron deficiency (iron saturation <15%) and those with serum creatinine >150 mmol/L were excluded. The prevalence of definite vitamin B(12) deficiency (vitamin B(12) level < 150 pmol/L and MMA >or= 0.4 micromol/L) was 42%. Another 32.8% had possible vitamin B(12) deficiency (either criterion). The prevalence of iron deficiency was 10%. After exclusions, 96 subjects were further analyzed. Vitamin B(12) deficiency defined by serum vitamin B(12) and MMA was associated with a decrease in hemoglobin concentrations by up to 0.9 g/dL, but it was not associated with an increase in mean corpuscular volume (MCV). Serum MMA but not vitamin B(12) levels correlated inversely with hemoglobin and platelet counts and positively with MCV, after adjustment of confounding factors. However, the percentage of subjects with anemia did not increase significantly until serum MMA became >1.0 micromol/L. In conclusion, vitamin B(12) deficiency was associated with a significant decrease in hemoglobin concentration. However, anemia associated with vitamin B(12) deficiency was seldom macrocytic. We recommend that older vegetarians should be given vitamin B(12) supplements routinely.
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Lai WK, Dillier N. A simple two-component model of the electrically evoked compound action potential in the human cochlea. Audiol Neurootol 2000; 5:333-45. [PMID: 11025333 DOI: 10.1159/000013899] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Neural response telemetry (NRT) permits in situ intracochlear recordings of the electrically evoked compound action potential from the auditory nerves using scala tympani electrodes. The recorded NRT waveforms can generally be categorized under either single positive peak or double positive peak waveforms. This is similar to the observations from Stypulkowski and van den Honert, who suggested that the double peak complex arises from two components that could be axonal and dendritic in origin, respectively. Using a simple mathematical model which linearly combines two separate waveforms similar in shape but differing in amplitude and latencies, it was possible to simulate the various NRT waveform categories. The simulation results support the view that the two waveform components originate from dendritic or axonal processes and implies that the shape of the response waveform may provide information about the degree of neural survival in the stimulated cochlea. This information could be useful for determining optimal speech coding parameters for cochlear implant users on an individual basis.
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Li CK, Yuen PM, Wong R, Pang CP, Lai WK, Law E, Shing MM, Chik KW, Leung TF. Busulphan level and early mortality in thalassaemia patients after BMT. Bone Marrow Transplant 1999; 23:307-10. [PMID: 10100572 DOI: 10.1038/sj.bmt.1701584] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The aim of the study was to correlate busulphan (BU) levels of thalassaemia patients with outcome of allogeneic transplant. BU levels were measured by gas chromatography mass fragmentography. All patients received a standardised dose of BU 16 mg/kg, and cyclophosphamide 150 or 200 mg/kg. For area-under-the-curve analysis (AUC), blood samples were obtained at 0, 1, 2, 3, 4 and 6 h after the first and fifth dose for all patients, and additional levels were measured after ninth and/or 13th dose in most patients. Outcome parameters examined included veno-occlusive disease of liver (VOD), idiopathic interstitial pneumonitis, chimerism, and day 90 survival. Twenty consecutive thalassaemia patients who underwent haematopoietic stem cell transplantation were studied. The median age at transplant was 11.2 years (range 3-21 years). Mean BU AUC levels were correlated with age at transplant (r = 0.58, P = 0.007). Nine patients developed VOD and six had mixed chimerism, but these did not correlate with mean BU AUC level. Four patients died before day 50 from VOD and interstitial pneumonitis. Patients with BU AUC levels greater than the median (908 micromol x min/l) had significantly lower probability of survival at day 90 (60%), whereas patients with BU AUC level less than the median all survived beyond day 90. No patient had graft rejection. In conclusion, a high BU AUC level was associated with a higher treatment-related mortality in thalassaemia patients after transplant.
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Lai WK, Pang CP, Law LK, Wong R, Li CK, Yuen PM. Routine analysis of plasma busulfan by gas chromatography-mass fragmentography. Clin Chem 1998; 44:2506-10. [PMID: 9836718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Busulfan (BU) is a widely used alkylating agent for antineoplastic therapy and marrow ablation in preparation for bone marrow transplantation (BMT). High-dose BU often leads to successful preparation and low relapse but is associated with veno-occlusive disease of liver. We established a protocol to determine postdosage plasma BU concentrations by gas chromatography-mass fragmentography in an attempt to relate clinical outcome to plasma BU concentrations. We used nonisotopic pusulfan as the internal standard. After extraction into ethyl acetate, BU and pusulfan were iodinated into 1, 4-diiodobutane and 1,5-diiodopentane, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis was carried out on an Hewlett-Packard (HP) 5890II gas chromatograph with a 30-m 100% methyl silicon narrow bore, fused-silica capillary column interfaced with an HP 5970A mass spectrometer. Helium was the carrier gas. The sample molecules were identified by total ion monitoring and quantified by selective ion monitoring of m/z 183 and 197. The calibration curve was linear to 4 mg/L. The limit of quantification was 0.04 mg/L, and the analytical recovery was approximately 97%. The within-day and between-day imprecision (CV) was <6% and 9%, respectively. In a preliminary study of 12 children, the BU areas under the BU-time curve were 616-949 micromol. min/L after the first dose and 793-1143 micromol. min/L after the fifth dose. We conclude that the GC-MS procedure is suitable for routine analysis of plasma BU.
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Kwok T, Tang C, Woo J, Lai WK, Law LK, Pang CP. Randomized trial of the effect of supplementation on the cognitive function of older people with subnormal cobalamin levels. Int J Geriatr Psychiatry 1998; 13:611-6. [PMID: 9777425 DOI: 10.1002/(sici)1099-1166(199809)13:9<611::aid-gps832>3.0.co;2-o] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Low serum cobalamin levels are often found in apparently normal older subjects. A major worry of leaving cobalamin deficiency untreated is that it may lead to subtle deterioration in cognitive function. OBJECTIVES To investigate the effect of supplementation on the cognitive function of older people with cobalamin deficiency by a randomized trial. METHODS Fifty Chinese subjects more than 60 years old with serum cobalamin level < 120 pmol/l were randomized into supplement and control groups. Fasting serum methylmalonic acid levels (MMA) were measured. A battery of neuropsychological tests was administered. The supplement group received intramuscular cyanocobalamin injections, while the control group received no intervention. They were followed up at around 4 months. RESULTS 78% of the subjects had raised MMA, indicating metabolic cobalamin deficiency. Supplemented subjects improved in performance IQ, but the amount of improvement was not significantly more than that of control subjects. Moreover, the supplement group fared worse than the control group at follow-up in some motor function scores. Three out of seven demented subjects had improvement in Mini-Mental State Examination scores, but there was no consistent improvement in other neuropsychological scores. CONCLUSIONS This study suggested that cobalamin deficiency did not invariably cause cognitive impairment in older people. There remain the possibilities that cobalamin deficiency causes cognitive impairment or exacerbates coexisting dementia in some older people.
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Lai WK, Dillier N, Laszig R, Fisch U. Results from a pilot study using the nucleus CI24M/SP5 cochlear implant system. THE AMERICAN JOURNAL OF OTOLOGY 1997; 18:S35-6. [PMID: 9391588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To conduct a pilot study in adults with the Nucleus CI24M/SP5 cochlear implant system. PATIENTS AND METHODS Eight postlingually deafened adults who had received little or no benefit from conventional hearing aids, equipped with the Nucleus CI24M/SP5 cochlear implant system. RESULTS AND CONCLUSIONS The results indicate that most of the subjects were able to perform well in speech recognition tests. The test performances appeared to be strongly affected by the duration of deafness. The speech processor's four user-selectable program memories have been extremely useful for the subjects to evaluate variations to the speech coding strategies in ordinary surroundings outside of the laboratory. The telemetry functions of the new implant provide a set of useful clinical and research tools for gathering greater insights into the in-situ operation of the implant.
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Allen L, Babiker M, Lai WK, Lembessis VE. Atom dynamics in multiple Laguerre-Gaussian beams. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1996; 54:4259-4270. [PMID: 9913976 DOI: 10.1103/physreva.54.4259] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Morice AH, Lai WK. Fatal varicella zoster infection in a severe steroid dependent asthmatic patient receiving methotrexate. Thorax 1995; 50:1221-2. [PMID: 8553283 PMCID: PMC475099 DOI: 10.1136/thx.50.11.1221] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A case is described of fatal haemorrhagic varicella zoster in a steroid dependent asthmatic patient concurrently receiving methotrexate. The future management of patients on immunosuppressive steroid sparing drugs is discussed.
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Lai WK, Dillier N. Glide psychophysics and related Mpeak and Speak speech performance. THE ANNALS OF OTOLOGY, RHINOLOGY & LARYNGOLOGY. SUPPLEMENT 1995; 166:368-370. [PMID: 7668710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Speech test results have indicated that improvements in speech comprehension can be achieved by means of coding strategies with high pulse rates. A possible effect of using high rates to encode speech information is that temporal information such as formant transitions could be better represented in the resulting electrode activity. A psychophysical study involving 4 cochlear implant users was carried out to observe the effect of various carrier pulse rates on the absolute identification of stimuli with a transient electrode trajectory. Also, the duration of the trajectory was varied. The results from this study indicated, first, that the trajectory identification became progressively more difficult as the duration of the trajectory was shortened. The identification score generally deteriorated much faster at a lower rate (100 pulses per second [pps]) than at higher rates (300 and 500 pps) with decreasing transient duration. The higher two pulse rates, 300 pps and 500 pps, yielded results similar to one another for longer (500 and 300 milliseconds) transient durations, but the identification of shorter (100 and 50 milliseconds) transient durations was better at 500 pps than at 300 pps. The implication is that higher carrier pulse rates are likely to be able to transmit short transient information better than lower ones. A comparison with speech test results using the Speak (spectral peak) speech-coding strategy shows that the place of articulation feature is significantly improved when compared to the slower-rate Mpeak (Multipeak) pitch-synchronous strategy.
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