Decreased postural adaptation in patients with phobic postural vertigo—An effect of an “anxious” control of posture?

Postural adaptability and responses elicited by vibratory stimulation to the calf muscles recorded on a force platform with eyes open or closed were analyzed in 39 patients suffering from Postural Phobic Vertigo (PPV) (17 men and 22 women, mean age 49 years) and 24 healthy subjects (14 men, 10 women, mean age 38 years). The vibration induced increased body sway in both groups, but the adaptation pattern differed significantly. With eyes open the PPV patients decreased their induced body sway over time (−32%, p < 0.01), which the controls did not. With eyes closed the PPV patients reduced their induced body sway over time to a much lesser extent than the controls (PPV: −28%, p < 0.05, controls: −57%, p < 0.001). These new findings show that PPV patients adapt to proprioceptive perturbation to a lesser extent than normal subjects and that PPV patients do not use visual information as efficiently to modulate postural control. The results support the hypothesis that a cognitive set of posture, an “anxious control”, may underlie the symptoms of PPV, i.e. an increased readiness to react to any perturbation or deviation.     

Choreathetosis due to abuse of levothyroxine

Journal of Neurology - Choreathetosis due to thyrotoxicosis is a rare movement disorder of acute onset. Here we present the first report of choreathetosis secondary to abuse of levothyroxine. A...     

Ultralow contrast medium doses at CT to diagnose pulmonary embolism in patients with moderate to severe renal impairment: a feasibility study

Objectives  

To analyse 80-kVp 16-MDCT in patients with clinically suspected pulmonary embolism (PE) and diminished renal function after a reduction in dose of contrast medium (CM) from 200 to 150 mg I/kg.     

Tensor kernels for simultaneous fiber model estimation and tractography

This paper proposes a novel framework for joint orientation distribution function estimation and tractography based on a new class of tensor kernels. Existing techniques estimate the local fiber orientation at each voxel independently so there is no running knowledge of confidence in the measured signal or estimated fiber orientation. In this work, fiber tracking is formulated as recursive estimation: at each step of tracing the fiber, the current estimate of the orientation distribution function is guided by the previous. To do this, second‐and higher‐order tensor‐based kernels are employed. A weighted mixture of these tensor kernels is used for representing crossing and branching fiber structures. While tracing a fiber, the parameters of the mixture model are estimated based on the orientation distribution function at that location and a smoothness term that penalizes deviation from the previous estimate along the fiber direction. This ensures smooth estimation along the direction of propagation of the fiber. In synthetic experiments, using a mixture of two and three components it is shown that this approach improves the angular resolution at crossings. In vivo experiments using two and three components examine the corpus callosum and corticospinal tract and confirm the ability to trace through regions known to contain such crossing and branching. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Feasibility of in vivo measurement of carotid wall shear rate using spiral fourier velocity encoded MRI

Arterial wall shear stress is widely believed to influence the formation and growth of atherosclerotic plaque; however, there is currently no gold standard for its in vivo measurement. The use of phase contrast MRI has proved to be challenging due to partial‐volume effects and inadequate signal‐to‐noise ratio at the high spatial resolutions that are required. This work evaluates the use of spiral Fourier velocity encoded MRI as a rapid method for assessing wall shear rate in the carotid arteries. Wall shear rate is calculated from velocity histograms in voxels spanning the blood/vessel wall interface, using a method developed by Frayne and Rutt (Magn Reson Med 1995;34:378–387). This study (i) demonstrates the accuracy of the velocity histograms measured by spiral Fourier velocity encoding in a pulsatile carotid flow phantom compared with high‐resolution two‐dimensional Fourier transform phase contrast, (ii) demonstrates the accuracy of Fourier velocity encoding–based shear rate measurements in a numerical phantom designed using a computational fluid dynamics simulation of carotid flow, and (iii) demonstrates in vivo measurement of regional wall shear rate and oscillatory shear index in the carotid arteries of healthy volunteers at 3 T. Magn Reson Med 63:1537–1547, 2010. © 2010 Wiley‐Liss, Inc.     

Common variants in human CRC genes as low-risk alleles

The genetic susceptibility to colorectal cancer (CRC) has been estimated to be around 35% and yet high-penetrance germline mutations found so far explain less than 5% of all cases. Much of the remaining variations could be due to the co-inheritance of multiple low penetrant variants. The identification of all the susceptibility alleles could have public health relevance in the near future. To test the hypothesis that what are considered polymorphisms in human CRC genes could constitute low-risk alleles, we selected eight common SNPs for a pilot association study in 1785 cases and 1722 controls. One SNP, rs3219489:G>C (MUTYH Q324H) seemed to confer an increased risk of rectal cancer in homozygous status (OR = 1.52; CI = 1.06–2.17). When the analysis was restricted to our ‘super-controls’, healthy individuals with no family history for cancer, also rs1799977:A>G (MLH1 I219V) was associated with an increased risk in both colon and rectum patients with an odds ratio of 1.28 (CI = 1.02–1.60) and 1.34 (CI = 1.05–1.72), respectively (under the dominant model); while 2 SNPs, rs1800932:A>G (MSH6 P92P) and rs459552:T>A (APC D1822V) seemed to confer a protective effect. The latter, in particular showed an odds ratio of 0.76 (CI = 0.60–0.97) among colon patients and 0.73 (CI = 0.56–0.95) among rectal patients. In conclusion, our study suggests that common variants in human CRC genes could constitute low-risk alleles.     

Non-stem cell origin for oligodendroglioma

Malignant astrocytic brain tumors are among the most lethal cancers. Quiescent and therapy-resistant neural stem cell (NSC)-like cells in astrocytomas are likely to contribute to poor outcome. Malignant oligodendroglial brain tumors, in contrast, are therapy sensitive. Using magnetic resonance imaging (MRI) and detailed developmental analyses, we demonstrated that murine oligodendroglioma cells show characteristics of oligodendrocyte progenitor cells (OPCs) and are therapy sensitive, and that OPC rather than NSC markers enriched for tumor formation. MRI of human oligodendroglioma also suggested a white matter (WM) origin, with markers for OPCs rather than NSCs similarly enriching for tumor formation. Our results suggest that oligodendroglioma cells show hallmarks of OPCs, and that a progenitor rather than a NSC origin underlies improved prognosis in patients with this tumor.