Lack of effect of pravastatin on cerebral blood flow or parenchymal volume loss in elderly at risk for vascular disease

<p><b>Background and Purpose:</b> Ageing is associated with a decline in cerebral blood flow. Animal studies have shown that cholesterol-lowering therapy with statins might preserve cerebral blood flow (CBF). We examined the effect of 40 mg pravastatin on the decline in CBF and brain volume in a subset of elderly subjects participating in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) trial.</p> <p><b>Methods:</b> Randomization was not stratified according to whether or not subjects participated in the MRI substudy. In 391 men (n=226) and women (n=165) aged 70 to 82 years (mean±SD, 75±3.2), we measured total CBF (in mL/min) at baseline and after a mean±SD follow-up of 33±1.4 months with a gradient-echo phase-contrast MRI technique. Total CBF was defined as the summed flows in both internal carotid and vertebral arteries. Parenchymal volume (whole brain) was segmented with the use of in-house–developed semiautomatic software.</p> <p><b>Results:</b> Total CBF significantly declined in the placebo-allocated group, from 521±83 to 504±92 mL/min (P=0.0036) and in the pravastatin-allocated group from 520±94 to 506±92 mL/min (P=0.018). This decline was not significantly different between treatment groups (P=0.56). There was also a significant reduction in brain volume over time (P<0.001), which was not different between the treatment groups (P=0.47). When expressed per unit of parenchymal volume, the decline in CBF over time was no longer statistically significant.</p> <p><b>Conclusions:</b> Elderly people at risk for cerebral vascular disease had a significant decline in CBF with increasing age that was explained by a concomitant reduction in brain volume. Treatment with 40 mg pravastatin daily had no beneficial effect on total CBF.</p&gt

Direct in vivo assessment of sex-related metabolic differences in a mouse model of Alzheimer's disease by MRI

Solid state NMR/Biophysical Organic Chemistr

The cinepheur: post-cinematic passage, post-perceptual passage

This thesis develops a hermeneutic commensurate with the aesthetic and ontological challenges of what Steven Shaviro describes as a post-cinematic media ecology, and Shane Denson describes as an emergent post-perceptual media ecology. I consider canonicity and cinephilia as frustrated efforts to contain and comprehend this new cinematic media object, offering a third unit of interpretation in their place, which I describe as the cinetopic anecdote. I associate the cinetopic anecdote with a particular way of moving between cinema and cinematic infrastructure, which I label cinetopic passage, and with a subject position that I label the cinepheur. Drawing on Walter Benjamin’s theory of the flâneur, I argue that the cinetopic anecdote precludes the extraction of a privileged cinematic moment in the manner characteristic of Christian Keathley’s cinephilic anecdote, but instead compels the cinepheur to instantiate, embody or physically recreate the infrastructural conditions that produced it, dovetailing production and consumption into what Axel Bruns has described as the emergent category of produsage; “unfinished artifacts, continuing process.” Having elaborated the cinetopic anecdote, I apply it to postmodern, post-cinematic and post-perceptual media ecologies, in order to evoke the peculiar forms of attachment and obsession bound up with the Criterion and Netflix platforms. In the process, I draw on Franco Moretti’s conception of distant reading to frame the cinetopic anecdote as a unit of distant viewing, offering distant viewings of Angela Christlieb and Stephen Kijak’s Cinemania, Sidney Lumet’s Garbo Talks and Pier Paolo Pasolini’s Salò, or The 120 Days of Sodom. Just as distant reading takes “the great unread” as its object of enquiry, so the cinetopic anecdote speaks to a media ecology preoccupied by the “great unviewed,” in which cinematic scarcity increasingly ramifies as an elegaic object

White matter microstructure of patients with neurofibromatosis type 1 and its relation to inhibitory control

Neuro Imaging Researc

Wave reflection at the origin of a first-generation branch artery and target organ protection: the AGES-Reykjavik study

Excessive pressure and flow pulsatility in first-generation branch arteries are associated with microvascular damage in high-flow organs like brain and kidneys. However, the contribution of local wave reflection and rereflection to microvascular damage remains controversial. Aortic flow, carotid pressure, flow and hydraulic power, brain magnetic resonance images, and cognitive scores were assessed in AGES-Reykjavik study participants without history of stroke, transient ischemic attack, or dementia (N=668, 378 women, 69-93 years of age). The aorta-carotid interface was generalized as a markedly asymmetrical bifurcation, with a large parent vessel (proximal aorta) branching into small (carotid) and large (distal aorta) daughter vessels. Local reflection coefficients were computed from aortic and carotid characteristic impedances. The bifurcation reflection coefficient, which determines pressure amplification in both daughter vessels, was low (0.06 +/- 0.03). The carotid flow transmission coefficient was low (0.11 +/- 0.04) and associated with markedly lower carotid versus aortic flow pulsatility (waveform SD, 7.2 +/- 2.0 versus 98.7 +/- 21.8 mL/s, P<0.001), pulsatility index (1.8 +/- 0.5 versus 4.5 +/- 0.6, P<0.001), and pulsatile power percentage (10 +/- 4% versus 25 +/- 5%, P<0.001). Transmitted as compared to incident pulsatile power (19.0 +/- 9.8 versus 35.9 +/- 17.8 mW, P<0.001) was further reduced by reflection (-4.3 +/- 2.7 mW) and rereflection (-12.5 +/- 8.1 mW) within the carotid. Higher carotid flow pulsatility correlated with lower white matter volume (R=-0.130, P<0.001) and lower memory scores (R=-0.161, P<0.001). Marked asymmetry of characteristic impedances at aorta-branch artery bifurcations limits amplification of pressure, markedly reduces absolute and relative pulsatility of transmitted flow and hydraulic power into first-generation branch arteries, and thereby protects the downstream local microcirculation from pulsatile damage.Neuro Imaging Researc

State of the art imaging in Meniere's disease. Tips and tricks for protocol and interpretation

Purpose of ReviewMeniere's disease (MD) is a burdensome and not well understood inner ear disorder that has received increasing attention of scientists over the past decade. Until 2007, a certain diagnosis of endolymphatic hydrops (EH) required post-mortem histology. Today, dedicated high-resolution magnetic resonance imaging (MRI) protocols enable detection of disease-related changes in the membranous labyrinth in vivo. In this review, we summarize the current status of MR imaging for MD.Recent FindingsThe mainstays of hydrops imaging are inversion recovery sequences using delayed acquisition after intravenous or intratympanic contrast administration. Based on these techniques, several methods have been developed to detect and classify EH. In addition, novel imaging features of MD, such as blood-labyrinth barrier impairment, have recently been observed.SummaryDelayed contrast enhanced MRI has emerged as a reliable technique to demonstrate EH in vivo, with promising application in the diagnosis and follow-up of MD patients. Therefore, familiarity with current techniques and diagnostic imaging criteria is increasingly important

Ultra-long-TE arterial spin labeling reveals rapid and brain-wide blood-to-CSF water transport in humans

The study of brain clearance mechanisms is an active area of research. While we know that the cerebrospinal fluid (CSF) plays a central role in one of the main existing clearance pathways, the exact processes for the secretion of CSF and the removal of waste products from tissue are under debate. CSF is thought to be created by the exchange of water and ions from the blood, which is believed to mainly occur in the choroid plexus. This exchange has not been thoroughly studied in vivo.We propose a modified arterial spin labeling (ASL) MRI sequence and image analysis to track blood water as it is transported to the CSF, and to characterize its exchange from blood to CSF. We acquired six pseudo-continuous ASL sequences with varying labeling duration (LD) and post-labeling delay (PLD) and a segmented 3D-GRASE readout with a long echo train (8 echo times (TE)) which allowed separation of the very long-T-2 CSF signal. ASL signal was observed at long TEs (793 ms and higher), indicating presence of labeled water transported from blood to CSF. This signal appeared both in the CSF proximal to the choroid plexus and in the subarachnoid space surrounding the cortex. ASL signal was separated into its blood, gray matter and CSF components by fitting a triexponential function with T(2)s taken from literature. A two-compartment dynamic model was introduced to describe the exchange of water through time and TE. From this, a water exchange time from the blood to the CSF (Tbl->CSF) was mapped, with an order of magnitude of approximately 60 s.Neuro Imaging Researc

In vivo localized two dimensional MR spectroscopy to compare the neurochemical profile in wild-type and transgenic mouse of Alzheimer’s disease

Solid state NMR/Biophysical Organic Chemistr