The Experts below are selected from a list of 90243 Experts worldwide ranked by ideXlab platform
Johannes Vogel - One of the best experts on this subject based on the ideXlab platform.
-
Quantifying Western blots: pitfalls of Densitometry.
Electrophoresis, 2009Co-Authors: Max Gassmann, Beat Grenacher, Bianca Rohde, Johannes VogelAbstract:Although Western blots are frequently quantified, Densitometry is not documented and appears to be based merely on traditions and guesswork. Confirming previous experience, none of 100 randomly selected and systematically scanned most recent papers provided sufficient information on how Western blot results were translated into statistical values. The importance of such information, however, becomes evident from our correlations of plasma erythropoietin values of various mammals determined using RIA and Western blot Densitometry. Different common Densitometry procedures applied to the identical Western blot revealed p-values of these correlations ranging from 0.000013 to 0.76 reflecting the necessity of a scientifically sound basis for Densitometry of Western blots. At present, the current lack of any definitions in Densitometry opens the door to uncontrollable acquisition of any desired p-value. Here we provide data that define what should be considered, what avoided and what documented when quantifying Western blots.
Jos J. Rozema - One of the best experts on this subject based on the ideXlab platform.
-
Scheimpflug Densitometry in Keratoconus: A New Method of Visualizing the Cone.
Cornea, 2020Co-Authors: Marta Jiménez-garcía, Sorcha Ní Dhubhghaill, Alejandra Consejo, Sarah Hershko, Carina Koppen, Jos J. RozemaAbstract:PURPOSE To report an observation made while performing Scheimpflug Densitometry analysis on the corneal region affected in keratoconus (KC) that seems to delineate the base of the cone. METHODS Scheimpflug densitometries of 20 healthy subjects and 90 patients with KC were examined. Corneal Densitometry was analyzed using both "1-layer" and "2-layer" approaches. The first considers the corneal transparency layer by layer at different depths, whereas the second averages Densitometry between 2 corneal layers selected by the examiner. Fixed layers, 120 μm depth, and endothelium were selected. Repeated same-day scans and longitudinal series of scans were also evaluated to see whether the findings evolved over time. RESULTS Eighty-eight of 90 KC cases displayed a bright area on the Densitometry map that corresponded to the cone location. The area's characteristics, such as its brightness, contrast, and the presence of a delimiting arc correlated with KC severity and was more noticeable in advanced cases. No similar marks were found in any of the normal subjects. The shape, location, and extent of the mark were consistent over consecutive measures taken on the same day. Changes over time were also seen in eyes with known clinical progression but was also seen in eyes considered clinically stable. CONCLUSIONS The Densitometry mark seems to correspond with the zone most affected by KC and could be a supplementary tool for documenting KC stage, alongside conventional parameters. Further studies are required to ascertain whether it could prove useful in KC detection, to determine progression, and to relate it to corneal biomechanical behavior.
-
Age-Related Corneal Transparency Changes Evaluated With an Alternative Method to Corneal Densitometry.
Cornea, 2020Co-Authors: Alejandra Consejo, Marta Jiménez-garcía, Jos J. RozemaAbstract:PURPOSE To compare Densitometry distribution analysis (DDA), a platform-independent method to assess corneal transparency, with traditional corneal Densitometry. METHODS A total of 196 healthy participants aged 43.3 ± 18.0 years (range 18-79 years) were recruited for assessment. All participants were assessed using the corneal Densitometry analysis add-on to the standard software of the Oculus Pentacam HR. In addition, the Scheimpflug image corresponding to the horizontal meridian of each participant was exported for further analysis. For each image, corneal pixel intensities were statistically modeled. The estimated output parameters, α and β, were compared with the corresponding Densitometry values. The analysis was performed considering 3 concentric areas and 3 layers defined at fixed corneal depths. To demonstrate the platform independence of the DDA method, a randomly selected subset of 80 participants also had their eye measured with Oculus Corvis ST. RESULTS α and β were found to be well correlated with Densitometry, especially α (overall cornea; r = 0.89, P < 0.001), independent of the corneal region investigated. Changes in α, β, and corneal Densitometry were correlated with age. CONCLUSIONS In this work, we presented the relationship of DDA with age and traditional corneal Densitometry. The α and β parameters, the output of DDA, are platform independent and can be used to investigate corneal clarity objectively.
-
Normative values for corneal Densitometry analysis by Scheimpflug optical assessment.
Investigative ophthalmology & visual science, 2014Co-Authors: Sorcha Ní Dhubhghaill, Jos J. Rozema, Sien Jongenelen, Irene Ruiz Hidalgo, Nadia Zakaria, Marie-josé TassignonAbstract:PURPOSE: To describe the normative data for corneal Scheimpflug Densitometry based on a cohort of normal participants. METHODS: A total of 445 healthy participants were recruited for assessment (794 eyes). Left and right eyes were considered separately. All participants were assessed using the corneal Densitometry analysis add-on to the standard software of the Oculus Pentacam. Densitometry measurements were obtained and expressed in standardized grayscale units (GSU). RESULTS: All participants were Caucasian; 42% were male and 58% were female. The mean age was 48.0 ± 15.3 years (range, 20.2-84.2 years). Mean corneal Densitometry over the 12-mm-diameter area was 19.74 ± 3.89 GSU. When divided by radial zone, Densitometry values were lowest in the central zone (16.76 ± 1.87 GSU) and highest in the periphery (27.36 ± 7.47 GSU). There was no difference between central zone and the surrounding 2- to 6-mm annulus (P > 0.05), though the 6- to 10-mm and the 10- to 12-mm zones displayed higher Densitometry values (P < 0.001). When divided by depth, the anterior layer displayed the highest Densitometry reading of 25.81 ± 5.14 GSU, which was significantly higher than that of both the central (P < 0.001) and the posterior layers (P < 0.001). Changes in corneal Densitometry were correlated with age, though not within the central 6-mm-diameter ring. No sex difference was seen within the cohort. CONCLUSIONS: This add-on to the standard imaging software allows rapid and objective assessment of the corneal Densitometry. We provide normative data that may be used as a reference facilitating research and complementing clinical examination.
Max Gassmann - One of the best experts on this subject based on the ideXlab platform.
-
Quantifying Western blots: pitfalls of Densitometry.
Electrophoresis, 2009Co-Authors: Max Gassmann, Beat Grenacher, Bianca Rohde, Johannes VogelAbstract:Although Western blots are frequently quantified, Densitometry is not documented and appears to be based merely on traditions and guesswork. Confirming previous experience, none of 100 randomly selected and systematically scanned most recent papers provided sufficient information on how Western blot results were translated into statistical values. The importance of such information, however, becomes evident from our correlations of plasma erythropoietin values of various mammals determined using RIA and Western blot Densitometry. Different common Densitometry procedures applied to the identical Western blot revealed p-values of these correlations ranging from 0.000013 to 0.76 reflecting the necessity of a scientifically sound basis for Densitometry of Western blots. At present, the current lack of any definitions in Densitometry opens the door to uncontrollable acquisition of any desired p-value. Here we provide data that define what should be considered, what avoided and what documented when quantifying Western blots.
Samir A Melki - One of the best experts on this subject based on the ideXlab platform.
-
corneal Densitometry as a tool to measure epithelial ingrowth after laser in situ keratomileusis
Cornea, 2017Co-Authors: Daniel Adran, Louis Vaillancourt, Mona Harissidagher, Jonathan N Kruh, Zeba A Syed, Steven Robinson, Samir A MelkiAbstract:PURPOSE: This study evaluates the correlation between corneal Densitometry and epithelial ingrowth (EI) after laser in situ keratomileusis (LASIK). METHODS: Corneal Densitometry of 3 patients who developed EI after LASIK was measured with the Oculus Pentacam. Corneal Densitometry readings of each patient were obtained preoperatively and postoperatively after ingrowth was discovered. Densitometry was recorded at the central nest of opacity and at the leading edges of EI. RESULTS: For all patients, the most severe stages of EI observed on slit-lamp photographs correlated with the highest Densitometry readings, with peak Densitometry ranging from 73.3 to 95.1. These values were much higher than preoperative Densitometry readings, which ranged from 21.8 to 27.2. In 2 cases, the Pentacam Densitometry map revealed progression of EI toward the visual axis that was only faintly detectable or not detectable at all on the corresponding slit-lamp photographs. CONCLUSIONS: Corneal Densitometry seems to be an objective measure of the severity and progression of EI after LASIK.
Bianca Rohde - One of the best experts on this subject based on the ideXlab platform.
-
Quantifying Western blots: pitfalls of Densitometry.
Electrophoresis, 2009Co-Authors: Max Gassmann, Beat Grenacher, Bianca Rohde, Johannes VogelAbstract:Although Western blots are frequently quantified, Densitometry is not documented and appears to be based merely on traditions and guesswork. Confirming previous experience, none of 100 randomly selected and systematically scanned most recent papers provided sufficient information on how Western blot results were translated into statistical values. The importance of such information, however, becomes evident from our correlations of plasma erythropoietin values of various mammals determined using RIA and Western blot Densitometry. Different common Densitometry procedures applied to the identical Western blot revealed p-values of these correlations ranging from 0.000013 to 0.76 reflecting the necessity of a scientifically sound basis for Densitometry of Western blots. At present, the current lack of any definitions in Densitometry opens the door to uncontrollable acquisition of any desired p-value. Here we provide data that define what should be considered, what avoided and what documented when quantifying Western blots.