A high-throughput SAMDI-mass spectrometry assay for isocitrate dehydrogenase 1.

The enzyme isocitrate dehydrogenase 1 (IDH1) catalyzes the conversion of isocitrate to alpha-ketoglutarate (αKG) and has emerged as an important therapeutic target for glioblastoma multiforme (GBM). Current methods for assaying IDH1 remain poorly suited for high-throughput screening of IDH1 antagonists. This paper describes a high-throughput and quantitative assay for IDH1 that is based on the self-assembled monolayers for matrix-assisted laser desorption/ionization-mass spectrometry (SAMDI-MS) method. The assay uses a self-assembled monolayer presenting a hydrazide group that covalently captures the αKG product of IDH1, where it can then be detected by MALDI-TOF mass spectrometry. Co-capture of an isotopically-labeled αKG internal standard allows the αKG concentration to be quantitated. The assay was used to analyze a series of standard αKG solutions and produced minimal error in measured αKG concentration values. The suitability of the assay for high-throughput analysis was evaluated in a 384-sample biochemical IDH1 screen. Cells expressing IDH1 were lysed and the lysate was applied to the monolayer to capture αKG, which was then quantitated using the SAMDI-MS assay. Cells in which IDH1 expression was reduced by small-interfering RNA exhibited a corresponding decrease in αKG concentration as measured by the assay. Application of the assay toward the high-throughput screening of IDH1 inhibitors or knockdown agents may facilitate the discovery of treatments for GBM.

Wide Variation in Radiation Exposure During Computerized Tomography.

OBJECTIVE: To determine the variance in computeed tomography (CT) radiation measured via dose-length product (DLP) and effective dose (ED) during stone protocol CT scans. METHODS: We retrospectively examined consecutive records of patients receiving stone protocol diagnostic CT scans (n = 1793) in 2010 and 2014 in our health system. Patient age, body mass index (BMI), and gender were recorded, along with the hospital, machine model, year, DLP, and ED of each scan. Multivariate regression was performed to identify predictive factors for increased DLP. We also collected data on head (n = 837) CT scans to serve as a comparison. RESULTS: For stone CT scans, mean patient age was 55.1 ± 18.4 years with no significant difference in age (P=.2557) or BMI (P=.1794) between 2010 and 2014. Gender, BMI, and machine model were independent predictors of radiation dosage (P < .0001). Within each BMI class, there was an inexplicable 6-fold variation in the ED for the same imaging test when comparing the lowest and highest CT dose patients. There was no significant change in DLP over time for stone CT scans, but head scan patients in 2014 received lower radiation doses than those in 2010 (P < .0001). Low-dose scans for renal colic (defined as <4 mSv) were underutilized. Substantial variation exists for head scan radiation doses. CONCLUSION: Our data demonstrate large variations in diagnostic CT radiation dosage. Such differences within a single institution suggest similar trends elsewhere, warranting more stringent dosage guidelines and regulations for diagnostic CT scans within institutions.

A comparative analysis of online education resources for patients undergoing endoscopic transsphenoidal surgery.

OBJECTIVE: Endoscopic transsphenoidal surgery has become the most commonly performed surgical procedure for pituitary tumor removal. As such, there are many patient-oriented educational materials on the technique available online for members of the public who desire to learn more about the surgery. It has been recommended that educational resources be written to the national average reading level, which in the United States is between sixth and seventh grade. This study assesses the reading level of the educational materials currently available online for endoscopic transsphenoidal surgery and determines whether these resources are written at a suitable comprehension level for most readers. METHODS: Sixteen patient educational resources describing endoscopic transsphenoidal surgery were identified online and assessed using 4 standard readability assessments. RESULTS: Patient educational resources written for endoscopic transsphenoidal surgery are written far above the recommended reading level of sixth grade. CONCLUSIONS: The online educational resources written for patients about endoscopic transsphenoidal surgery are above the recommended reading level for patient education materials. Further revisions to simplify these resources on endoscopic transsphenoidal surgery are needed to ensure that most patients can comprehend this important material and make informed decisions about their health care.