The Experts below are selected from a list of 39195 Experts worldwide ranked by ideXlab platform
Konrad P Weber - One of the best experts on this subject based on the ideXlab platform.
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Hierarchical Cluster Analysis of Semicircular Canal and Otolith Deficits in Bilateral Vestibulopathy
Frontiers in neurology, 2018Co-Authors: Alexander A Tarnutzer, Christopher J Bockisch, Elena Buffone, Konrad P WeberAbstract:Background Gait imbalance and oscillopsia are frequent complaints of bilateral vestibular loss (BLV). Video-head-impulse testing (vHIT) of all six semicircular canals (SCCs) has demonstrated varying involvement of the different canals. Sparing of anterior-canal function has been linked to aminoglycoside-related vestibulopathy and Meniere's disease. We hypothesized that utricular and saccular impairment [assessed by vestibular-evoked myogenic potentials (VEMPs)] may be disease-specific also, possibly facilitating the differential diagnosis. Methods We searched our vHIT database ( = 3,271) for patients with bilaterally impaired SCC function who also received ocular VEMPs (oVEMPs) and cervical VEMPs (cVEMPs) and identified 101 patients. oVEMP/cVEMP latencies above the 95th percentile and peak-to-peak amplitudes below the 5th percentile of normal were considered abnormal. Frequency of impairment of vestibular end organs (horizontal/anterior/posterior SCC, utriculus/sacculus) was analyzed with Hierarchical Cluster Analysis and correlated with the underlying etiology. Results Rates of utricular and saccular loss of function were similar (87.1 vs. 78.2%, = 0.136, Fisher's exact test). oVEMP abnormalities were found more frequent in aminoglycoside-related bilateral vestibular loss (BVL) compared with Meniere's disease (91.7 vs. 54.6%, = 0.039). Hierarchical Cluster Analysis indicated distinct patterns of vestibular end-organ impairment, showing that the results for the same end-organs on both sides are more similar than to other end-organs. Relative sparing of anterior-canal function was reflected in late merging with the other end-organs, emphasizing their distinct state. An anatomically corresponding pattern of SCC/otolith hypofunction was present in 60.4% (oVEMPs vs. horizontal SCCs), 34.7% (oVEMPs vs. anterior SCCs), and 48.5% (cVEMPs vs. posterior SCCs) of cases. Average (±1 SD) number of damaged sensors was 6.8 ± 2.2 out of 10. Significantly (
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Hierarchical Cluster Analysis of semicircular canal and otolith deficits in bilateral vestibulopathy
Frontiers in Neurology, 2018Co-Authors: Alexander A Tarnutzer, Christopher J Bockisch, Elena Buffone, Konrad P WeberAbstract:Background Gait imbalance and oscillopsia are frequent complaints of bilateral vestibular loss (BLV). Video-head-impulse testing (vHIT) of all six semicircular canals (SCCs) has demonstrated varying involvement of the different canals. Sparing of anterior-canal function has been linked to aminoglycoside-related vestibulopathy and Meniere's disease. We hypothesized that utricular and saccular impairment [assessed by vestibular-evoked myogenic potentials (VEMPs)] may be disease-specific also, possibly facilitating the differential diagnosis. Methods We searched our vHIT database ( = 3,271) for patients with bilaterally impaired SCC function who also received ocular VEMPs (oVEMPs) and cervical VEMPs (cVEMPs) and identified 101 patients. oVEMP/cVEMP latencies above the 95th percentile and peak-to-peak amplitudes below the 5th percentile of normal were considered abnormal. Frequency of impairment of vestibular end organs (horizontal/anterior/posterior SCC, utriculus/sacculus) was analyzed with Hierarchical Cluster Analysis and correlated with the underlying etiology. Results Rates of utricular and saccular loss of function were similar (87.1 vs. 78.2%, = 0.136, Fisher's exact test). oVEMP abnormalities were found more frequent in aminoglycoside-related bilateral vestibular loss (BVL) compared with Meniere's disease (91.7 vs. 54.6%, = 0.039). Hierarchical Cluster Analysis indicated distinct patterns of vestibular end-organ impairment, showing that the results for the same end-organs on both sides are more similar than to other end-organs. Relative sparing of anterior-canal function was reflected in late merging with the other end-organs, emphasizing their distinct state. An anatomically corresponding pattern of SCC/otolith hypofunction was present in 60.4% (oVEMPs vs. horizontal SCCs), 34.7% (oVEMPs vs. anterior SCCs), and 48.5% (cVEMPs vs. posterior SCCs) of cases. Average (±1 SD) number of damaged sensors was 6.8 ± 2.2 out of 10. Significantly ( < 0.001) more sensors were impaired in patients with aminoglycoside-related BVL (8.1 ± 1.2) or inner-ear infections (8.7 ± 1.8) compared with Meniere-related BVL (5.5 ± 1.5). Discussion Hierarchical Cluster Analysis may help differentiate characteristic patterns of BVL. With a prevalence of ≈80%, utricular and/or saccular impairment is frequent in BVL. The extent of SCC and otolith impairment was disease-dependent, showing most extensive damage in BVL related to inner-ear infection and aminoglycoside-exposure and more selective impairment in Meniere's disease. Specifically, assessing utricular function may help in the distinction between aminoglycoside-related BVL and bilateral Meniere's disease.
Chan Yun Kim - One of the best experts on this subject based on the ideXlab platform.
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A Hierarchical Cluster Analysis of normal-tension glaucoma using spectral-domain optical coherence tomography parameters.
Journal of glaucoma, 2015Co-Authors: Hyoung Won Bae, Hye Sun Lee, Naeun Lee, Samin Hong, Gong Je Seong, Kyung Rim Sung, Chan Yun KimAbstract:PURPOSE Normal-tension glaucoma (NTG) is a heterogenous disease, and there is still controversy about subclassifications of this disorder. On the basis of spectral-domain optical coherence tomography (SD-OCT), we subdivided NTG with Hierarchical Cluster Analysis using optic nerve head (ONH) parameters and retinal nerve fiber layer (RNFL) thicknesses. PATIENTS AND METHODS A total of 200 eyes of 200 NTG patients between March 2011 and June 2012 underwent SD-OCT scans to measure ONH parameters and RNFL thicknesses. We classified NTG into homogenous subgroups based on these variables using a Hierarchical Cluster Analysis, and compared Clusters to evaluate diverse NTG characteristics. RESULTS Three Clusters were found after Hierarchical Cluster Analysis. Cluster 1 (62 eyes) had the thickest RNFL and widest rim area, and showed early glaucoma features. Cluster 2 (60 eyes) was characterized by the largest cup/disc ratio and cup volume, and showed advanced glaucomatous damage. Cluster 3 (78 eyes) had small disc areas in SD-OCT and were comprised of patients with significantly younger age, longer axial length, and greater myopia than the other 2 groups. CONCLUSIONS A Hierarchical Cluster Analysis of SD-OCT scans divided NTG patients into 3 groups based upon ONH parameters and RNFL thicknesses. It is anticipated that the small disc area group comprised of younger and more myopic patients may show unique features unlike the other 2 groups.
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Hierarchical Cluster Analysis of progression patterns in open-angle glaucoma patients with medical treatment.
Investigative ophthalmology & visual science, 2014Co-Authors: Hyoung Won Bae, Hye Sun Lee, Naeun Lee, Samin Hong, Gong Je Seong, Kyung Rim Sung, Seungsoo Rho, Chan Yun KimAbstract:PURPOSE To classify medically treated open-angle glaucoma (OAG) by the pattern of progression using Hierarchical Cluster Analysis, and to determine OAG progression characteristics by comparing Clusters. METHODS Ninety-five eyes of 95 OAG patients who received medical treatment, and who had undergone visual field (VF) testing at least once per year for 5 or more years. OAG was classified into subgroups using Hierarchical Cluster Analysis based on the following five variables: baseline mean deviation (MD), baseline visual field index (VFI), MD slope, VFI slope, and Glaucoma Progression Analysis (GPA) printout. After that, other parameters were compared between Clusters. RESULTS Two Clusters were made after a Hierarchical Cluster Analysis. Cluster 1 showed -4.06 ± 2.43 dB baseline MD, 92.58% ± 6.27% baseline VFI, -0.28 ± 0.38 dB per year MD slope, -0.52% ± 0.81% per year VFI slope, and all "no progression" cases in GPA printout, whereas Cluster 2 showed -8.68 ± 3.81 baseline MD, 77.54 ± 12.98 baseline VFI, -0.72 ± 0.55 MD slope, -2.22 ± 1.89 VFI slope, and seven "possible" and four "likely" progression cases in GPA printout. There were no significant differences in age, sex, mean IOP, central corneal thickness, and axial length between Clusters. However, Cluster 2 included more high-tension glaucoma patients and used a greater number of antiglaucoma eye drops significantly compared with Cluster 1. CONCLUSIONS Hierarchical Cluster Analysis of progression patterns divided OAG into slow and fast progression groups, evidenced by assessing the parameters of glaucomatous progression in VF testing. In the fast progression group, the prevalence of high-tension glaucoma was greater and the number of antiglaucoma medications administered was increased versus the slow progression group.
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A Hierarchical Cluster Analysis of primary angle closure classification using anterior segment optical coherence tomography parameters.
Investigative ophthalmology & visual science, 2013Co-Authors: Seung-hee Baek, Kyung Rim Sung, Chan Yun Kim, Jae Hong Sun, Jong Rak Lee, Kyoung Sub Lee, Kilhwan ShonAbstract:PURPOSE To investigate the possibility of classifying angle closure eyes in terms of features provided by anterior segment optical coherence tomography (AS OCT). METHODS Angle closure (primary angle closure [PAC] or PAC glaucoma [PACG]) eyes diagnosed by gonioscopy were imaged using AS OCT under the same lighting conditions. Anterior chamber depth (ACD), anterior chamber width (ACW), iris cross-sectional area (IA), iris thickness at 750 μm from the scleral spur (IT750), iris curvature (IC), lens vault (LV), and anterior chamber area (ACA) were determined using Image J software (ver. 1.44). A Hierarchical Cluster Analysis using Ward's method was performed using AS parameters obtained by AS OCT and axial length (AXL). RESULTS A Hierarchical Cluster Analysis was performed on 166 angle closure eyes and produced two Clusters. The first Cluster (84 eyes) was characterized by higher ACD (2.24 mm), higher ACA (12.5 mm(2)), higher IT750 (0.44 mm), higher ACW (11.2 mm), lower LV (0.85 mm), and higher AXL (23.5 mm) compared with the second Cluster (82 eyes, 1.82 mm, 9.5 mm(2), 0.38 mm, 10.8 mm, 1.1 mm, and 22.8 mm, respectively). The second Cluster had essentially higher LV and lower ACA than the first Cluster. Most parameters were significantly different between two Clusters except IC (P = 0.76). CONCLUSIONS Our Hierarchical Cluster Analysis indicated two Clusters with quite different features existed in our total angle closure population. Our results suggest the possibility of subclassifying angle closure eyes according to AS OCT parameters.
Alexander A Tarnutzer - One of the best experts on this subject based on the ideXlab platform.
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Hierarchical Cluster Analysis of Semicircular Canal and Otolith Deficits in Bilateral Vestibulopathy
Frontiers in neurology, 2018Co-Authors: Alexander A Tarnutzer, Christopher J Bockisch, Elena Buffone, Konrad P WeberAbstract:Background Gait imbalance and oscillopsia are frequent complaints of bilateral vestibular loss (BLV). Video-head-impulse testing (vHIT) of all six semicircular canals (SCCs) has demonstrated varying involvement of the different canals. Sparing of anterior-canal function has been linked to aminoglycoside-related vestibulopathy and Meniere's disease. We hypothesized that utricular and saccular impairment [assessed by vestibular-evoked myogenic potentials (VEMPs)] may be disease-specific also, possibly facilitating the differential diagnosis. Methods We searched our vHIT database ( = 3,271) for patients with bilaterally impaired SCC function who also received ocular VEMPs (oVEMPs) and cervical VEMPs (cVEMPs) and identified 101 patients. oVEMP/cVEMP latencies above the 95th percentile and peak-to-peak amplitudes below the 5th percentile of normal were considered abnormal. Frequency of impairment of vestibular end organs (horizontal/anterior/posterior SCC, utriculus/sacculus) was analyzed with Hierarchical Cluster Analysis and correlated with the underlying etiology. Results Rates of utricular and saccular loss of function were similar (87.1 vs. 78.2%, = 0.136, Fisher's exact test). oVEMP abnormalities were found more frequent in aminoglycoside-related bilateral vestibular loss (BVL) compared with Meniere's disease (91.7 vs. 54.6%, = 0.039). Hierarchical Cluster Analysis indicated distinct patterns of vestibular end-organ impairment, showing that the results for the same end-organs on both sides are more similar than to other end-organs. Relative sparing of anterior-canal function was reflected in late merging with the other end-organs, emphasizing their distinct state. An anatomically corresponding pattern of SCC/otolith hypofunction was present in 60.4% (oVEMPs vs. horizontal SCCs), 34.7% (oVEMPs vs. anterior SCCs), and 48.5% (cVEMPs vs. posterior SCCs) of cases. Average (±1 SD) number of damaged sensors was 6.8 ± 2.2 out of 10. Significantly (
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Hierarchical Cluster Analysis of semicircular canal and otolith deficits in bilateral vestibulopathy
Frontiers in Neurology, 2018Co-Authors: Alexander A Tarnutzer, Christopher J Bockisch, Elena Buffone, Konrad P WeberAbstract:Background Gait imbalance and oscillopsia are frequent complaints of bilateral vestibular loss (BLV). Video-head-impulse testing (vHIT) of all six semicircular canals (SCCs) has demonstrated varying involvement of the different canals. Sparing of anterior-canal function has been linked to aminoglycoside-related vestibulopathy and Meniere's disease. We hypothesized that utricular and saccular impairment [assessed by vestibular-evoked myogenic potentials (VEMPs)] may be disease-specific also, possibly facilitating the differential diagnosis. Methods We searched our vHIT database ( = 3,271) for patients with bilaterally impaired SCC function who also received ocular VEMPs (oVEMPs) and cervical VEMPs (cVEMPs) and identified 101 patients. oVEMP/cVEMP latencies above the 95th percentile and peak-to-peak amplitudes below the 5th percentile of normal were considered abnormal. Frequency of impairment of vestibular end organs (horizontal/anterior/posterior SCC, utriculus/sacculus) was analyzed with Hierarchical Cluster Analysis and correlated with the underlying etiology. Results Rates of utricular and saccular loss of function were similar (87.1 vs. 78.2%, = 0.136, Fisher's exact test). oVEMP abnormalities were found more frequent in aminoglycoside-related bilateral vestibular loss (BVL) compared with Meniere's disease (91.7 vs. 54.6%, = 0.039). Hierarchical Cluster Analysis indicated distinct patterns of vestibular end-organ impairment, showing that the results for the same end-organs on both sides are more similar than to other end-organs. Relative sparing of anterior-canal function was reflected in late merging with the other end-organs, emphasizing their distinct state. An anatomically corresponding pattern of SCC/otolith hypofunction was present in 60.4% (oVEMPs vs. horizontal SCCs), 34.7% (oVEMPs vs. anterior SCCs), and 48.5% (cVEMPs vs. posterior SCCs) of cases. Average (±1 SD) number of damaged sensors was 6.8 ± 2.2 out of 10. Significantly ( < 0.001) more sensors were impaired in patients with aminoglycoside-related BVL (8.1 ± 1.2) or inner-ear infections (8.7 ± 1.8) compared with Meniere-related BVL (5.5 ± 1.5). Discussion Hierarchical Cluster Analysis may help differentiate characteristic patterns of BVL. With a prevalence of ≈80%, utricular and/or saccular impairment is frequent in BVL. The extent of SCC and otolith impairment was disease-dependent, showing most extensive damage in BVL related to inner-ear infection and aminoglycoside-exposure and more selective impairment in Meniere's disease. Specifically, assessing utricular function may help in the distinction between aminoglycoside-related BVL and bilateral Meniere's disease.
Kyung Rim Sung - One of the best experts on this subject based on the ideXlab platform.
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A Hierarchical Cluster Analysis of normal-tension glaucoma using spectral-domain optical coherence tomography parameters.
Journal of glaucoma, 2015Co-Authors: Hyoung Won Bae, Hye Sun Lee, Naeun Lee, Samin Hong, Gong Je Seong, Kyung Rim Sung, Chan Yun KimAbstract:PURPOSE Normal-tension glaucoma (NTG) is a heterogenous disease, and there is still controversy about subclassifications of this disorder. On the basis of spectral-domain optical coherence tomography (SD-OCT), we subdivided NTG with Hierarchical Cluster Analysis using optic nerve head (ONH) parameters and retinal nerve fiber layer (RNFL) thicknesses. PATIENTS AND METHODS A total of 200 eyes of 200 NTG patients between March 2011 and June 2012 underwent SD-OCT scans to measure ONH parameters and RNFL thicknesses. We classified NTG into homogenous subgroups based on these variables using a Hierarchical Cluster Analysis, and compared Clusters to evaluate diverse NTG characteristics. RESULTS Three Clusters were found after Hierarchical Cluster Analysis. Cluster 1 (62 eyes) had the thickest RNFL and widest rim area, and showed early glaucoma features. Cluster 2 (60 eyes) was characterized by the largest cup/disc ratio and cup volume, and showed advanced glaucomatous damage. Cluster 3 (78 eyes) had small disc areas in SD-OCT and were comprised of patients with significantly younger age, longer axial length, and greater myopia than the other 2 groups. CONCLUSIONS A Hierarchical Cluster Analysis of SD-OCT scans divided NTG patients into 3 groups based upon ONH parameters and RNFL thicknesses. It is anticipated that the small disc area group comprised of younger and more myopic patients may show unique features unlike the other 2 groups.
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Hierarchical Cluster Analysis of progression patterns in open-angle glaucoma patients with medical treatment.
Investigative ophthalmology & visual science, 2014Co-Authors: Hyoung Won Bae, Hye Sun Lee, Naeun Lee, Samin Hong, Gong Je Seong, Kyung Rim Sung, Seungsoo Rho, Chan Yun KimAbstract:PURPOSE To classify medically treated open-angle glaucoma (OAG) by the pattern of progression using Hierarchical Cluster Analysis, and to determine OAG progression characteristics by comparing Clusters. METHODS Ninety-five eyes of 95 OAG patients who received medical treatment, and who had undergone visual field (VF) testing at least once per year for 5 or more years. OAG was classified into subgroups using Hierarchical Cluster Analysis based on the following five variables: baseline mean deviation (MD), baseline visual field index (VFI), MD slope, VFI slope, and Glaucoma Progression Analysis (GPA) printout. After that, other parameters were compared between Clusters. RESULTS Two Clusters were made after a Hierarchical Cluster Analysis. Cluster 1 showed -4.06 ± 2.43 dB baseline MD, 92.58% ± 6.27% baseline VFI, -0.28 ± 0.38 dB per year MD slope, -0.52% ± 0.81% per year VFI slope, and all "no progression" cases in GPA printout, whereas Cluster 2 showed -8.68 ± 3.81 baseline MD, 77.54 ± 12.98 baseline VFI, -0.72 ± 0.55 MD slope, -2.22 ± 1.89 VFI slope, and seven "possible" and four "likely" progression cases in GPA printout. There were no significant differences in age, sex, mean IOP, central corneal thickness, and axial length between Clusters. However, Cluster 2 included more high-tension glaucoma patients and used a greater number of antiglaucoma eye drops significantly compared with Cluster 1. CONCLUSIONS Hierarchical Cluster Analysis of progression patterns divided OAG into slow and fast progression groups, evidenced by assessing the parameters of glaucomatous progression in VF testing. In the fast progression group, the prevalence of high-tension glaucoma was greater and the number of antiglaucoma medications administered was increased versus the slow progression group.
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A Hierarchical Cluster Analysis of primary angle closure classification using anterior segment optical coherence tomography parameters.
Investigative ophthalmology & visual science, 2013Co-Authors: Seung-hee Baek, Kyung Rim Sung, Chan Yun Kim, Jae Hong Sun, Jong Rak Lee, Kyoung Sub Lee, Kilhwan ShonAbstract:PURPOSE To investigate the possibility of classifying angle closure eyes in terms of features provided by anterior segment optical coherence tomography (AS OCT). METHODS Angle closure (primary angle closure [PAC] or PAC glaucoma [PACG]) eyes diagnosed by gonioscopy were imaged using AS OCT under the same lighting conditions. Anterior chamber depth (ACD), anterior chamber width (ACW), iris cross-sectional area (IA), iris thickness at 750 μm from the scleral spur (IT750), iris curvature (IC), lens vault (LV), and anterior chamber area (ACA) were determined using Image J software (ver. 1.44). A Hierarchical Cluster Analysis using Ward's method was performed using AS parameters obtained by AS OCT and axial length (AXL). RESULTS A Hierarchical Cluster Analysis was performed on 166 angle closure eyes and produced two Clusters. The first Cluster (84 eyes) was characterized by higher ACD (2.24 mm), higher ACA (12.5 mm(2)), higher IT750 (0.44 mm), higher ACW (11.2 mm), lower LV (0.85 mm), and higher AXL (23.5 mm) compared with the second Cluster (82 eyes, 1.82 mm, 9.5 mm(2), 0.38 mm, 10.8 mm, 1.1 mm, and 22.8 mm, respectively). The second Cluster had essentially higher LV and lower ACA than the first Cluster. Most parameters were significantly different between two Clusters except IC (P = 0.76). CONCLUSIONS Our Hierarchical Cluster Analysis indicated two Clusters with quite different features existed in our total angle closure population. Our results suggest the possibility of subclassifying angle closure eyes according to AS OCT parameters.
Marc Lamy De La Chapelle - One of the best experts on this subject based on the ideXlab platform.
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rapid screening of colistin resistant escherichia coli acinetobacter baumannii and pseudomonas aeruginosa by the use of raman spectroscopy and Hierarchical Cluster Analysis
Analyst, 2019Co-Authors: Zhongquan Lin, Wei Liu, Xiang Zhao, Jiaoqi Huang, Yuting Zheng, Xiang Yang, Yang Zhang, Marc Lamy De La ChapelleAbstract:Colistin is recognized as the last therapeutic option for multidrug-resistant Gram-negative bacteria infection. In addition, bacterial resistance to colistin could be transmitted between different species through plasmid-mediated mcr-1 gene transfer. Therefore, rapid screening of colistin-resistant isolates will play a key role in controlling the spread of resistance and improving patient outcomes. We developed a rapid method for the detection of colistin-resistance in Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa bacteria based on Raman spectroscopy and Hierarchical Cluster Analysis. Bacteria were incubated with and without colistin using CAMHB as the liquid culture medium. They were then centrifuged and dried on a glass slide. Five Raman spectra of each of the samples were recorded and analyzed by the Hierarchical Cluster Analysis method to determine whether the bacteria were resistant. To evaluate this method, 123 clinical bacterial isolates (42 isolates of E. coli, 41 isolates of A. baumannii and 40 isolates of P. aeruginosa) were tested. The detection sensitivity and specificity were 90.9% and 91.1%, respectively, compared with the reference broth microdilution method. The screening is easy to perform and can be completed in 1.5 h, suggesting that it holds great potential to be an initial screening method in countries and areas where colistin becomes the last resort antibiotic.
