Abnormal nuclear aggregation and myotube degeneration in myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is caused by CTG nucleotide repeat expansions in the 3'-untranslated region (3'-UTR) of the dystrophia myotonica protein kinase (DMPK) gene. The expanded CTG repeats encode toxic CUG RNAs that cause disease, largely through RNA gain-of-function. DM1 is a fatal disease characterized by progressive muscle wasting, which has no cure. Regenerative medicine has emerged as a promising therapeutic modality for DM1, especially with the advancement of induced pluripotent stem (iPS) cell technology and therapeutic genome editing. However, there is an unmet need to identify in vitro outcome measures to demonstrate the therapeutic effects prior to in vivo clinical trials. In this study, we examined the muscle regeneration (myotube formation) in normal and DM1 myoblasts in vitro to establish outcome measures for therapeutic monitoring. We found normal proliferation of DM1 myoblasts, but abnormal nuclear aggregation during the early stage myotube formation, as well as myotube degeneration during the late stage of myotube formation. We concluded that early abnormal nuclear aggregation and late myotube degeneration offer easy and sensitive outcome measures to monitor therapeutic effects in vitro.

The effect of iron status on gadolinium deposition in the rat brain: mechanistic implications.

Introduction: Sites associated with gadolinium (Gd) deposition in the brain (e.g., the globus pallidus) are known to contain high concentrations of ferric iron. There is considerable debate over the mechanism of Gd deposition in the brain. The role of iron transport mechanisms in Gd deposition has not been determined. Thus, we seek to identify if Gd deposition can be controlled by modifying iron exposure. Methods: Female Sprague-Dawley rats were given diets with controlled iron levels at 2-6 ppm, 6 ppt (20 g/kg Fe carbonyl) or 48 ppm for 3 weeks to induce iron deficiency, overload or normalcy. They were kept on those diets while receiving a cumulative 10 mmol/kg dose of gadodiamide intravenously over 2 weeks, then left to washout gadodiamide for 3 days or 3 weeks before tissues were harvested. Gd concentrations in tissues were analyzed by ICP-MS. Results: There were no significant effect of dietary iron and total Gd concentrations in the organs, but there was a significant effect of iron status on Gd distribution in the brain. For the 3-week washout cohort, there was a non-significant trend of increasing total brain deposition and decreasing dietary iron, and about 4-fold more Gd in the olfactory bulbs of the low iron group compared to the other groups. Significant brain accumulation was observed in the low iron group total brain Gd in the 3-week washout group relative to the 3-day washout group and no accumulation was observed in other tissues. There was a strong negative correlation between femur Gd concentrations and concentrations in other organs when stratifying by dietary iron. Discussion: Gd brain deposition from linear Gd-based contrast agents (GBCAs) are dependent upon iron status, likely through variable transferrin saturation. This iron dependence appears to be associated with redistribution of peripheral deposited Gd (e.g., in the bone) into the brain.

Deficiencies with CAGE-AID questionnaire in identifying nonmedical opioid use-a report of two cases.

BACKGROUND: The CAGE-AID questionnaire (Cut-down, Annoyed, Guilty, Eye-opener scale Adapted to Include Drugs) is used to screen patients for substance use disorder and nonmedical opioid use (NMOU). Major pain guidelines encourage using such screening tools for all patients including cancer patients before initiating opioids. We present two cases where the CAGE-AID results did not accurately identify the risk for NMOU. CASE DESCRIPTION: Patient 1 is a male in his 60s with metastatic prostate cancer was admitted for uncontrolled pain. Imaging revealed extensive spinal metastasis, needing initiation of methadone and hydromorphone. The CAGE-AID score was positive, placing him at risk for NMOU. This likely biased the providers, delaying opioid titration. Subsequently, doses were adjusted, and he was discharged with adequate pain control and no evidence of NMOU. Patient 2 is a male in his 40s with metastatic cholangiocarcinoma admitted for uncontrolled abdominal pain. The patient had multiple hospitalizations at different facilities with similar symptoms. The CAGE-AID score was negative. Despite this, the patient demonstrated behaviors such as demanding intravenous opioids, dose escalation, or interventions such as nerve blocks. The workup did not identify any etiology for the increased pain. The patient left the hospital against medical advice when his demands for intravenous opioids were not met. CONCLUSIONS: The CAGE-AID questionnaire alone does not accurately identify risks for NMOU. Screening tools must always be accompanied by a thorough clinical assessment of behaviors and pain mechanism. More research is needed to better characterize CAGE-AID false positives and negatives among patients with cancer pain.