Neuropathology of microbleeds in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

Cerebral microbleeds (CMBs) detected on magnetic resonance imaging are common in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). The neuropathologic correlates of CMBs are unclear. In this study, we characterized findings relevant to CMBs in autopsy brain tissue of 8 patients with genetically confirmed CADASIL and 10 controls within the age range of the CADASIL patients by assessing the distribution and extent of hemosiderin/iron deposits including perivascular hemosiderin leakage (PVH), capillary hemosiderin deposits, and parenchymal iron deposits (PID) in the frontal cortex and white matter, basal ganglia and cerebellum. We also characterized infarcts, vessel wall thickening, and severity of vascular smooth muscle cell degeneration. CADASIL subjects had a significant increase in hemosiderin/iron deposits compared with controls. This increase was principally seen with PID. Hemosiderin/iron deposits were seen in the majority of CADASIL subjects in all brain areas. PVH was most pronounced in the frontal white matter and basal ganglia around small to medium sized arterioles, with no predilection for the vicinity of vessels with severe vascular changes or infarcts. CADASIL subjects have increased brain hemosiderin/iron deposits but these do not occur in a periarteriolar distribution. Pathogenesis of these lesions remains uncertain.

The impact of marijuana use on liver transplant recipients: A 900 patient single center experience.

INTRODUCTION: Increased societal prevalence of marijuana continues to challenge liver transplant (LT) programs. This study aimed to examine the potential effects of marijuana use on outcomes. METHODS: This retrospective study included recipients who underwent LT between 1/2012 and 6/2018. According to pre-LT marijuana use, patients were classified into recent (≤6 months of LT), former (chronic use but not ≤6 months), or non-users. Additionally, the impact of post-LT marijuana use on survival was assessed. RESULTS: Of 926 eligible patients, 184 were pre-LT marijuana users (42 recent; 142 former) (median follow-up: 30.3 months). Pre-users were more likely to be male, White, and have histories of tobacco, alcohol, and illicit drug use. Additionally, recent users were of higher acuity, with higher MELD and requiring ICU admission. Patient survival at 1-year was 89% in non-users, 94% (HR: 0.494, 95% CI: 0.239-1.022 vs. non-users) in former users, and 83% (HR: 1.516, 95% CI: 0.701-3.282) in recent users. Post-operative complications in pre-LT users and the survival analysis for post-LT marijuana users vs. non-users did not show significance. CONCLUSIONS: Our results demonstrated that marijuana use did not have an adverse impact on post-LT outcomes; however, further studies utilizing larger cohorts are warranted.

Correlation between Apparent Substrate Affinity and OCT2 Transport Turnover.

Organic cation (OC) transporter 2 (OCT2) mediates the first step in the renal secretion of many cationic drugs: basolateral uptake from blood into proximal tubule cells. The impact of this process on the pharmacokinetics of drug clearance as estimated using a physiologically-based pharmacokinetic approach relies on an accurate understanding of the kinetics of transport because the ratio of the maximal rate of transport to the Michaelis constant (i.e., Jmax/ Kt) provides an estimate of the intrinsic clearance (Clint) used in in vitro-in vivo extrapolation of experimentally determined transport data. Although the multispecificity of renal OC secretion, including that of the OCT2 transporter, is widely acknowledged, the possible relationship between relative affinity of the transporter for its diverse substrates and the maximal rates of their transport has received little attention. In this study, we determined the Jmax and apparent Michaelis constant (Ktapp) values for six structurally distinct OCT2 substrates and found a strong correlation between Jmax and Ktapp; high-affinity substrates [Ktapp values <50 µM, including 1-methyl-4-phenylpyridinium, or 1-methyl-4-phenylpyridinium (MPP), and cimetidine] displayed systematically lower Jmax values (<50 pmol cm-2 min-1) than did low-affinity substrates (Ktapp >200 µM, including choline and metformin). Similarly, preloading OCT2-expressing cells with low-affinity substrates resulted in systematically larger trans-stimulated rates of MPP uptake than did preloading with high-affinity substrates. The data are quantitatively consistent with the hypothesis that dissociation of bound substrate from the transporter is rate limiting in establishing maximal rates of OCT2-mediated transport. This systematic relationship may provide a means to estimate Clint for drugs for which transport data are lacking.