Refractive Development in the “ROP Rat”

Although retinopathy of prematurity (ROP) is clinically characterized by abnormal retinal vessels at the posterior pole of the eye, it is also commonly characterized by vascular abnormalities in the anterior segment, visual dysfunction which is based in retinal dysfunction, and, most commonly of all, arrested eye growth and high refractive error, particularly (and paradoxically) myopia. The oxygen-induced retinopathy rat model of ROP presents neurovascular outcomes similar to the human disease, although it is not yet known if the “ROP rat” also models the small-eyed myopia characteristic of ROP. In this study, magnetic resonance images (MRIs) of albino (Sprague-Dawley) and pigmented (Long-Evans) ROP rat eyes, and age- and strain-matched room-air-reared (RAR) controls, were examined. The positions and curvatures of the various optical media were measured and the refractive state (℞) of each eye estimated based on a previously published model. Even in adulthood (postnatal day 50), Sprague-Dawley and Long-Evans ROP rats were significantly myopic compared to strain-matched controls. The myopia in the Long-Evans ROP rats was more severe than in the Sprague-Dawley ROP rats, which also had significantly shorter axial lengths. These data reveal the ROP rat to be a novel and potentially informative approach to investigating physiological mechanisms in myopia in general and the myopia peculiar to ROP in particular

Human Tumor Cell Proliferation Evaluated Using Manganese-Enhanced MRI

Tumor cell proliferation can depend on calcium entry across the cell membrane. As a first step toward the development of a non-invasive test of the extent of tumor cell proliferation in vivo, we tested the hypothesis that tumor cell uptake of a calcium surrogate, Mn(2+) [measured with manganese-enhanced MRI (MEMRI)], is linked to proliferation rate in vitro.Proliferation rates were determined in vitro in three different human tumor cell lines: C918 and OCM-1 human uveal melanomas and PC-3 prostate carcinoma. Cells growing at different average proliferation rates were exposed to 1 mM MnCl(2) for one hour and then thoroughly washed. MEMRI R(1) values (longitudinal relaxation rates), which have a positive linear relationship with Mn(2+) concentration, were then determined from cell pellets. Cell cycle distributions were determined using propidium iodide staining and flow cytometry. All three lines showed Mn(2+)-induced increases in R(1) compared to cells not exposed to Mn(2+). C918 and PC-3 cells each showed a significant, positive correlation between MEMRI R(1) values and proliferation rate (p≤0.005), while OCM-1 cells showed no significant correlation. Preliminary, general modeling of these positive relationships suggested that pellet R(1) for the PC-3 cells, but not for the C918 cells, could be adequately described by simply accounting for changes in the distribution of the cell cycle-dependent subpopulations in the pellet.These data clearly demonstrate the tumor-cell dependent nature of the relationship between proliferation and calcium influx, and underscore the usefulness of MEMRI as a non-invasive method for investigating this link. MEMRI is applicable to study tumors in vivo, and the present results raise the possibility of evaluating proliferation parameters of some tumor types in vivo using MEMRI

Evidence of Key Tinnitus-Related Brain Regions Documented by a Unique Combination of Manganese-Enhanced MRI and Acoustic Startle Reflex Testing

Animal models continue to improve our understanding of tinnitus pathogenesis and aid in development of new treatments. However, there are no diagnostic biomarkers for tinnitus-related pathophysiology for use in awake, freely moving animals. To address this disparity, two complementary methods were combined to examine reliable tinnitus models (rats repeatedly administered salicylate or exposed to a single noise event): inhibition of acoustic startle and manganese-enhanced MRI. Salicylate-induced tinnitus resulted in wide spread supernormal manganese uptake compared to noise-induced tinnitus. Neither model demonstrated significant differences in the auditory cortex. Only in the dorsal cortex of the inferior colliculus (DCIC) did both models exhibit supernormal uptake. Therefore, abnormal membrane depolarization in the DCIC appears to be important in tinnitus-mediated activity. Our results provide the foundation for future studies correlating the severity and longevity of tinnitus with hearing loss and neuronal activity in specific brain regions and tools for evaluating treatment efficacy across paradigms

Productive Hepatitis C Virus Infection of Stem Cell-Derived Hepatocytes Reveals a Critical Transition to Viral Permissiveness during Differentiation

Primary human hepatocytes isolated from patient biopsies represent the most physiologically relevant cell culture model for hepatitis C virus (HCV) infection, but these primary cells are not readily accessible, display individual variability, and are largely refractory to genetic manipulation. Hepatocyte-like cells differentiated from pluripotent stem cells provide an attractive alternative as they not only overcome these shortcomings but can also provide an unlimited source of noncancer cells for both research and cell therapy. Despite its promise, the permissiveness to HCV infection of differentiated human hepatocyte-like cells (DHHs) has not been explored. Here we report a novel infection model based on DHHs derived from human embryonic (hESCs) and induced pluripotent stem cells (iPSCs). DHHs generated in chemically defined media under feeder-free conditions were subjected to infection by both HCV derived in cell culture (HCVcc) and patient-derived virus (HCVser). Pluripotent stem cells and definitive endoderm were not permissive for HCV infection whereas hepatic progenitor cells were persistently infected and secreted infectious particles into culture medium. Permissiveness to infection was correlated with induction of the liver-specific microRNA-122 and modulation of cellular factors that affect HCV replication. RNA interference directed toward essential cellular cofactors in stem cells resulted in HCV-resistant hepatocyte-like cells after differentiation. The ability to infect cultured cells directly with HCV patient serum, to study defined stages of viral permissiveness, and to produce genetically modified cells with desired phenotypes all have broad significance for host-pathogen interactions and cell therapy

Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data

Mars’s seismic activity and noise have been monitored since January 2019 by the seismometer of the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander. At night, Mars is extremely quiet; seismic noise is about 500 times lower than Earth’s microseismic noise at periods between 4 s and 30 s. The recorded seismic noise increases during the day due to ground deformations induced by convective atmospheric vortices and ground-transferred wind-generated lander noise. Here we constrain properties of the crust beneath InSight, using signals from atmospheric vortices and from the hammering of InSight’s Heat Flow and Physical Properties (HP3) instrument, as well as the three largest Marsquakes detected as of September 2019. From receiver function analysis, we infer that the uppermost 8–11 km of the crust is highly altered and/ or fractured. We measure the crustal diffusivity and intrinsic attenuation using multiscattering analysis and find that seismic attenuation is about three times larger than on the Moon, which suggests that the crust contains small amounts of volatiles

Acute Stroke Despite Dabigatran Anticoagulation Treated with Idarucizumab and Intravenous Tissue Plasminogen Activator

Dabigatran is a direct thrombin inhibitor used to reduce the risk of stroke in patients with nonvalvular atrial fibrillation. For patients who present with an acute stroke despite dabigatran therapy, clinical data on the use of intravenous tissue plasminogen activator (IV-tPA) is limited. There is an anticipated increased risk of symptomatic intracranial hemorrhage (sICH) when using IV-tPA in patients on dabigatran therapy. In 2015, the humanized monoclonal antibody fragment idarucizumab was approved for rapid (minutes) reversal of anticoagulant effects of dabigatran. Dabigatran reversal with idarucizumab before administration of IV-tPA might reduce the risk of sICH. We report a case of a 69-year-old stroke patient on dabigatran for paroxysmal atrial fibrillation who presented with an initial National Institutes of Health Stroke Scale (NIHSS) of 12. There was no early evidence of ischemic stroke or hemorrhage on head computed tomography, and coagulation studies implied therapeutic dabigatran levels. After controlling blood pressure, dabigatran was reversed with idarucizumab, and IV-tPA was administrated beginning 197 minutes after he was last seen at his baseline. Subsequent brain magnetic resonance imaging showed 2 punctate infarcts in the left temporal lobe and occipital lobe with no evidence of hemorrhage. The patient was discharged with an NIHSS of 1. Telephone follow-up 2 months later indicated that he was at his prestroke baseline, except for a complaint of worsened short-term memory. Idarucizumab reversal of dabigatran may reduce the risk of sICH and should be considered for acute stroke patients arriving in the IV-tPA time window

Rapid Disruption of Genes Specifically in Livers of Mice Using Multiplex CRISPR/Cas9 Editing

Background & aimsDespite advances in gene editing technologies, generation of tissue-specific knockout mice is time-consuming. We used CRISPR/Cas9-mediated genome editing to disrupt genes in livers of adult mice in just a few months, which we refer to as somatic liver knockouts.MethodsIn this system, Fah-/- mice are given hydrodynamic tail vein injections of plasmids carrying CRISPR/Cas9 designed to excise exons in Hpd; the Hpd-edited hepatocytes have a survival advantage in these mice. Plasmids that target Hpd and a separate gene of interest can therefore be used to rapidly generate mice with liver-specific deletion of nearly any gene product.ResultsWe used this system to create mice with liver-specific knockout of argininosuccinate lyase, which develop hyperammonemia, observed in humans with mutations in this gene. We also created mice with liver-specific knockout of ATP binding cassette subfamily B member 11, which encodes the bile salt export pump. We found that these mice have a biochemical phenotype similar to that of Abcb11-/- mice. We then used this system to knock out expression of 5 different enzymes involved in drug metabolism within the same mouse.ConclusionsThis approach might be used to develop new models of liver diseases and study liver functions of genes that are required during development

Clinical characteristics and outcomes of methamphetamine-associated intracerebral hemorrhage.

ObjectiveTo compare the clinical characteristics and outcomes of primary intracerebral hemorrhage (ICH) with and without methamphetamine exposure.MethodsWe performed a retrospective analysis of patients diagnosed with spontaneous, nontraumatic ICH over a 3-year period between January 2013 and December 2016. Demographics, clinical measures, and outcomes were compared between ICH patients with positive methamphetamine toxicology tests vs those with negative methamphetamine toxicology tests.ResultsMethamphetamine-positive ICH patients were younger than methamphetamine-negative ICH patients (52 vs 67 years, p < 0.001). Patients with methamphetamine-positive ICH had higher diastolic blood pressure (115 vs 101, p = 0.003), higher mean arterial pressure (144 vs 129, p = 0.01), longer lengths of hospital (18 vs 8 days, p < 0.001) and intensive care unit (ICU) stay (10 vs 5 days, p < 0.001), required more days of IV antihypertensive medications (5 vs 3 days, p = 0.02), and had more subcortical hemorrhages (63% vs 46%, p = 0.05). The methamphetamine-positive group had better premorbid modified Rankin Scale (mRS) scores (p < 0.001) and a greater change in functional ability as measured by mRS at the time of hospital discharge (p = 0.001). In multivariate analyses, methamphetamine use predicted both hospital length of stay (risk ratio [RR] 1.54, confidence interval [CI] 1.39-1.70, p < 0.001) and ICU length of stay (RR 1.36, CI 1.18-1.56, p < 0.001), but did not predict poor outcome (mRS 4-6).ConclusionsMethamphetamine use is associated with earlier age at onset of ICH, longer hospital stays, and greater change in functional ability, but did not predict outcome