Using primary cultures of oligodendrocyte progenitors isolated from male and female neonatal rodent brains, we observed more oligodendrocytes in female-derived compared to male-derived cultures. To ...determine whether the observed differences were due to a differential effect of sex hormones on proliferation, we treated cultures with increasing doses of 17beta-estradiol, testosterone or progesterone and labeled cells with bromodeoxyuridine to identify cells in S phase. Treatment with 17beta-estradiol, but not progesterone or testosterone, delayed the exit of oligodendrocyte progenitor cells from the cell cycle. In addition, 17beta-estradiol treatment enhanced membrane sheet formation, while progesterone increased cellular branching. Interestingly, the estrogen modulator tamoxifen mimicked the effect of 17beta-estradiol on cell cycle exit, but not on membrane formation. Immunocytochemical localization of estrogen receptors (ERs) showed ERbeta mainly localized to the cytoplasm of oligodendrocytes, suggesting that the effect of 17beta-estradiol on membrane formation could be mediated by interaction with this receptor. We conclude that sex steroids differentially regulate oligodendrocyte progenitor number and myelin formation, possibly contributing to gender-specific differences in repair.
We present new interferometric data obtained with mid-infrared interferometric instrument (MIDI) for the type II Seyfert galaxy NGC 1068, with an extensive coverage of 16 uv points. These ...observations resolve the nuclear mid-infrared emission from NGC 1068 in unprecedented detail with a maximum resolution of 7 mas. For the first time, sufficient uv points have been obtained, allowing us to generate an image of the source using maximum entropy image reconstruction. The features of the image are similar to those obtained by modelling. We find that the mid-infrared emission can be represented by two components, each with a Gaussian brightness distribution. The first, identified as the inner funnel of the obscuring torus, is hot (∼800 K), 1.35 parsec long and 0.45 parsec thick in full width at half-maximum (FWHM) at a PA =−42° (from north to east). It has an absorption profile different than standard interstellar dust and with evidence for clumpiness. The second component is 3 × 4 pc in FWHM with T=∼300 K, and we identify it with the cooler body of the torus. The compact component is tilted by ∼45° with respect to the radio jet and has similar size and orientation to the observed water maser distribution. We show how the dust distribution relates to other observables within a few parsec of the core of the galaxy, such as the nuclear masers, the radio jet and the ionization cone. We compare our findings to a similar study of the Circinus galaxy and other relevant studies. Our findings shed new light on the relation between the different parsec-scale components in NGC 1068 and the obscuring torus.
COVID-19 was initially described as a pulmonary disease. Increasing attention is now directed to extrapulmonary disease manifestations mediated by viral tropism to the vascular endothelium. Here, we ...report a case of an adult patient with COVID-19 who presented to the emergency department with neurological signs disproportionate to pulmonary symptoms and was found to have a subacute ischemic stroke. Imaging studies suggested an active inflammatory vasculopathy. The case highlights the utility of vascular wall imaging studies when positive findings are present on emergent CT angiography. Current treatment algorithms should consider the addition of adjunct intracranial vessel wall imaging to assess for inflammatory vasculopathy when a patient with acute or recent COVID infection presents to the emergency department with stroke.
Background and Purpose
The gold standard for imaging of meningiomas is MRI with gadolinium‐based contrast agent. Due to increased costs, time, and uncertain chronic effects of gadolinium exposure, ...use of noncontrast T2‐weighted imaging (T2WI) in lieu of contrast‐enhanced MRI has been an increasing focus of research across various diagnostic scenarios. The purpose of this study was to evaluate the diagnostic accuracy of T2WI in detecting changes in meningioma tumor volume.
Methods
Imaging and clinical data were reviewed for 82 consecutive patients undergoing MR‐surveillance of intracranial meningioma. Using volumetric‐T2WI, two neuroradiologists independently calculated tumor volumes. Measurements were compared to a baseline study contrast‐enhanced T1 tumor volume. Using contrast‐enhanced sequences as the reference standard, statistical analysis was performed to determine the accuracy of T2WI in detecting changes of meningioma volume.
Results
Using only T2WI, readers detected meningioma volume change ≥ 20% in 19/82 patients and volume change <20% in 63/82 patients. Reader accuracy for detecting change in tumor volume on T2WI ≥ 20% was 0.85, sensitivity 0.65, specificity 0.93, positive predictive value (PPV) 0.79, and negative predictive value (NPV) 0.87. For meningiomas >1 ml, reader accuracy for detecting change in tumor volume on T2WI ≥20% was 0.90, sensitivity 0.78, specificity 0.95, PPV 0.88, and NPV 0.91. Change in tumor volume on T2WI ≥20% was detected with 100% accuracy for posterior fossa meningiomas. Inter‐reader agreement for all meningiomas was moderate (κ = 0.45) improving to substantial agreement (κ = 0.77) with tumor volumes >1 ml.
Conclusion
Volumetric‐T2WI detects changes in meningioma volume with comparable accuracy to gold standard T1 postcontrast imaging, particularly with higher tumor volumes and posterior fossa locations.
Object
Diffusion MRI has been used to predict intraoperative consistency of tumors. Apparent diffusion coefficient (ADC) has shown predictive value as an imaging biomarker in many CNS tumors but has ...not been studied in a large cohort of patients with vestibular schwannoma. In this study, we examine the utility of ADC as a predictive biomarker for intraoperative tumor characteristics and postoperative facial nerve outcome.
Methods
A retrospective review of patients who underwent vestibular schwannoma resection at our institution from 2008 to 2018 yielded 87 patients, of which 72 met inclusion criteria. Operative reports and clinical records were reviewed for clinical data; MRI data were interpreted in a blinded fashion for qualitative and quantitative biomarkers, including tumor ADC.
Results
Mean tumor ADC values did not predict intraoperative consistency or adherence (
p
= 0.63). Adherent tumors were associated with worse facial nerve outcomes (
p
= 0.003). Regression tree analysis identified 3 ADC categories with statistically different facial nerve outcomes. The categories identified were ADC < 1006.04 × 10
−6
mm
2/
s; ADC 1006.04–1563.93 × 10
−6
mm
2/
s and ADC ≥ 1563.94 × 10
−6
mm
2/
s. Postoperative and final House-Brackmann (HB) scores were significantly higher in the intermediate ADC group (2.3,
p
= 0.0038). HB outcomes were similar between the group with ADC < 1006.04 × 10
−6
mm
2/
s and ≥ 1563.94 × 10
−6
mm
2/
s (1.3 vs 1.3).
Conclusions
Middle-range preoperative ADC in vestibular schwannoma suggests a less favorable postoperative HB score. Preoperative measurement of ADC in vestibular schwannoma may provide additional information regarding prognostication of facial nerve outcomes.
Remember Rachel Dolezal? An instructor of Africana Studies at Eastern Washington University and president of the Spokane chapter of the National Association for the Advancement of Colored People ...(NAACP), Dolezal hid her racial origin until 2015 when an intrepid reporter unmasked her. A follow-up with her parents revealed the truth: Dolezal isn’t black, she’s white. The public has largely forgotten this incident, but scholarly work has just begun. Research by Khaled A. Beydoun and Erika K. Wilson focuses on how the story of Rachel Dolezal is actually much broader and more complex than it initially appears; her story provided a starting point for a broader theory linking the historical phenomenon of passing, centuries of jurisprudence eroding white privilege, and the increasing prevalence of reverse passing.
We present new interferometric data obtained with MIDI (MID infrared Interferometric instrument) for the Seyfert II galaxy NGC 1068, with an extensive coverage of sixteen uv points. These ...observations resolve the nuclear mid-infrared emission from NGC 1068 in unprecedented detail with a maximum resolution of 7 mas. For the first time, sufficient uv points have been obtained, allowing us to generate an image of the source using maximum entropy image reconstruction. The features of the image are similar to those obtained by modelling. We find that the mid-infrared emission can be represented by two components, each with a Gaussian brightness distribution. The first, identified as the inner funnel of the obscuring torus, is hot (800K), 1.35 parsec long, and 0.45 parsec thick in FWHM at a PA=-42 degrees (from north to east). It has an absorption profile different than standard interstellar dust and with evidence for clumpiness. The second component is 3 by 4 pc in FWHM with T=300K, and we identify it with the cooler body of the torus. The compact component is tilted by 45 degrees with respect to the radio jet and has similar size and orientation to the observed water maser distribution. We show how the dust distribution relates to other observables within a few parsecs of the core of the galaxy such as the nuclear masers, the radio jet, and the ionization cone. We compare our findings to a similar study of the Circinus galaxy and other relevant studies. Our findings shed new light on the relation between the different parsec-scale components in NGC 1068 and the obscuring torus.
We report mid-IR interferometric measurements with \sim 10 mas resolution, which resolve the warm (T = 285 +25 / -50 K) thermal emission at the center of NGC 4151. Using pairs of VLT 8.2 m telescopes ...with MIDI and by comparing the data to a Gaussian model, we determined the diameter of the dust emission region, albeit only along one position angle, to be 2.0 +/- 0.4 pc (FWHM). This is the first size and temperature estimate for the nuclear warm dust distribution in a Seyfert 1 galaxy. The parameters found are comparable to those in Seyfert 2 galaxies, thus providing direct support for the unified model. Using simple analytic temperature distributions, we find that the mid-infrared emission is probably not the smooth continuation of the hot nuclear source that is marginally resolved with K band interferometry. We also detected weak excess emission around 10.5 micron in our shorter baseline observation, possibly indicating that silicate emission is extended to the parsec scale.
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