Endovascular management of ruptured choroidal aneurysms associated with moyamoya syndrome: A two-patient case report & review of the literature.

Ruptured choroidal microaneurysms associated with moyamoya syndrome are rare entities. Their small size and deep/distal location make them challenging to treat. Both surgical and endovascular treatment options carry significant risk of stroke. Here we present a two-patient case report of ruptured choroidal microaneurysms treated with Nbutyl cyanoacrylate (nBCA) endovascular embolization utilizing neuromonitoring and provocative testing during one of the cases. We also present a review of the literature evaluating surgical and endovascular treatment of these aneurysms

The highly specific, cell cycle–regulated methyltransferase from Caulobacter crescentus relies on a novel DNA recognition mechanism

Two DNA methyltransferases, Dam and β-class cell cycle-regulated DNA methyltransferase (CcrM), are key mediators of bacterial epigenetics. CcrM from the bacterium Caulobacter crescentus (CcrM C. crescentus, methylates adenine at 5'-GANTC-3') displays 105-107-fold sequence discrimination against noncognate sequences. However, the underlying recognition mechanism is unclear. Here, CcrM C. crescentus activity was either improved or mildly attenuated with substrates having one to three mismatched bp within or adjacent to the recognition site, but only if the strand undergoing methylation is left unchanged. By comparison, single-mismatched substrates resulted in up to 106-fold losses of activity with α (Dam) and γ-class (M.HhaI) DNA methyltransferases. We found that CcrM C. crescentus has a greatly expanded DNA-interaction surface, covering six nucleotides on the 5' side and eight nucleotides on the 3' side of its recognition site. Such a large interface may contribute to the enzyme's high sequence fidelity. CcrM C. crescentus displayed the same sequence discrimination with single-stranded substrates, and a surprisingly large (>107-fold) discrimination against ssRNA was largely due to the presence of two or more riboses within the cognate (DNA) site but not outside the site. Results from C-terminal truncations and point mutants supported our hypothesis that the recently identified C-terminal, 80-residue segment is essential for dsDNA recognition but is not required for single-stranded substrates. CcrM orthologs from Agrobacterium tumefaciens and Brucella abortus share some of these newly discovered features of the C. crescentus enzyme, suggesting that the recognition mechanism is conserved. In summary, CcrM C. crescentus uses a previously unknown DNA recognition mechanism

Efficacy of Radiation Reduction Protocols for Diagnostic Angiography and Basic Interventions in Endovascular Neurosurgery

Efficacy of Radiation Reduction Protocols for Diagnostic Angiography and Basic Interventions in Endovascular Neurosurgery  Arvin R. Wali MD, MAS, Michael G. Brandel MD, MAS, Sarath Pathuri BS, Brian R. Hirshman MD, PhD, Javier Bravo MD, Jeffrey Steinberg MD, Scott Olson MD, J. Scott Pannell MD, David R. Santiago-Dieppa MD, Alexander A. Khalessi MD, MBA  Background  Safe radiation practices and “As Low As Reasonably Achievable” (ALARA) principles are critical to mitigate unnecessary radiation to patients, providers, and staff. Radiation has stochastic and deterministic effects that have deleterious effects on health and lead to complications such as cancer, leukemia, and cataracts. As the indications for neuroendovascular procedures continue to grow, Neurointerventionalists must have a strong command over practices that reduce unnecessary radiation dose. We applied a quality improvement protocol to manipulate default pulse rate and frame rate settings on our Siemens Artis Q biplane to determine if radiation safety practices could allow for quality diagnostic angiograms and the performance of safe and effective interventions.  Methods We implemented a radiation reduction protocol January 1st 2022 in which the default pulse rate and frame rate in our Siemens Artis Q biplane was reduced from 15 pulses per second (p/s) to 7.5 p/s and 7.5 frames per second (f/s) to 4.0 f/s. We performed a retrospective review of prospectively acquired data to calculate the impact of our radiation reduction protocol on total radiation dose, radiation per angiographic run, total radiation exposure, and exposure per run.  We examined 29 consecutive diagnostic angiograms (16 prior to intervention, and 13 post intervention) and 16 consecutive, unilateral middle meningeal artery embolizations (MMAEs) (8 prior to intervention, and 8 post intervention). A blinded neuroradiologist reviewed the angiograms to determine if there was sufficient diagnostic information in the angiograms before and after intervention. Univariable and multivariable log-linear regression were performed to account for patient body mass index (BMI), number of angiographic runs, and number of vessels catheterized. Statistical analysis was performed using STATA MP Version 17.0 (Stata Corp LP, College Station, Texas). Significance was defined as p < 0.05.  Results For the diagnostic angiograms, univariable analysis revealed that radiation dose (550.5 vs. 353.3 mGy, p=0.005), radiation dose per angiographic run (34.6 vs. 21.9, p<0.001), total radiation exposure (7050.7 vs. 4490.7 mGym2, p=0.013), and exposure per run (429.8 vs. 281.9, p<0.001) were all significantly decreased after the protocol. On multivariable log-linear regression adjusting for BMI, number of runs, vessels catheterized, and fluoroscopy time, the protocol was associated with a 45.4% decrease in the total radiation dose (p<0.001) and a 53.3% decrease in radiation dose per run (p<0.001). For the MMAEs, univariable analysis revealed that radiation dose (660.9 vs. 407.5 mGy, p=0.002), radiation dose per angiographic run (40.3 vs. 25.7, p<0.001), total radiation exposure (8825.8 vs. 5510.4 mGym2, p=0.002), and exposure per run (537.9 vs. 353.5, p=0.002) were all significantly decreased after the protocol. Both groups were well balanced in terms of clinical characteristics (Table 1 and 2). No changes in image quality were identified by an expert interventional neuroradiologist. Fluoroscopy and procedural time did not differ between MMAE groups (20min vs 21min p=0.65).  Conclusions Radiation reduction protocols are highly effective for neuroendovascular interventions. We strongly encourage all interventionalists to be cognizant of pulse rate and frame rate when performing routine interventions to avoid unnecessary radiation towards patients, providers, and health care staff.&nbsp

Reducing frame rate and pulse rate for routine diagnostic cerebral angiography: ALARA principles in practice.

OBJECTIVE: Diagnostic cerebral angiograms (DCAs) are widely used in neurosurgery due to their high sensitivity and specificity to diagnose and characterize pathology using ionizing radiation. Eliminating unnecessary radiation is critical to reduce risk to patients, providers, and health care staff. We investigated if reducing pulse and frame rates during routine DCAs would decrease radiation burden without compromising image quality. METHODS: We performed a retrospective review of prospectively acquired data after implementing a quality improvement protocol in which pulse rate and frame rate were reduced from 15 p/s to 7.5 p/s and 7.5 f/s to 4.0 f/s respectively. Radiation doses and exposures were calculated. Two endovascular neurosurgeons reviewed randomly selected angiograms of both doses and blindly assessed their quality. RESULTS: A total of 40 consecutive angiograms were retrospectively analyzed, 20 prior to the protocol change and 20 after. After the intervention, radiation dose, radiation per run, total exposure, and exposure per run were all significantly decreased even after adjustment for BMI (all p<0.05). On multivariable analysis, we identified a 46% decrease in total radiation dose and 39% decrease in exposure without compromising image quality or procedure time. CONCLUSIONS: We demonstrated that for routine DCAs, pulse rate of 7.5 with a frame rate of 4.0 is sufficient to obtain diagnostic information without compromising image quality or elongating procedure time. In the interest of patient, provider, and health care staff safety, we strongly encourage all interventionalists to be cognizant of radiation usage to avoid unnecessary radiation exposure and consequential health risks