Differential vulnerability of white matter structures to experimental infantile hydrocephalus detected by diffusion tensor imaging

Purpose

The differential vulnerability of white matter (WM) to acute and chronic infantile hydrocephalus and the related effects of early and late reservoir treatment are unknown, but diffusion tensor imaging (DTI) could provide this information. Thus, we characterized WM integrity using DTI in a clinically relevant model.

Methods

Obstructive hydrocephalus was induced in 2-week-old felines by intracisternal kaolin injection. Ventricular reservoirs were placed 1 (early) or 2 (late) weeks post-kaolin and tapped frequently based solely on neurological deficit. Hydrocephalic and age-matched control animals were sacrificed 12 weeks postreservoir. WM integrity was evaluated in the optic system, corpus callosum, and internal capsule prereservoir and every 3 weeks using DTI. Analyses were grouped as acute (<6 weeks) or chronic (≥6 weeks).

Results

In the corpus callosum during acute stages, fractional anisotropy (FA) decreased significantly with early and late reservoir placement (p?=?0.0008 and 0.0008, respectively), and diffusivity increased significantly in early (axial, radial, and mean diffusivity, p?=?0.0026, 0.0012, and 0.0002, respectively) and late (radial and mean diffusivity, p?=?0.01 and 0.0038, respectively) groups. Chronically, the corpus callosum was thinned and not detectable by DTI. FA was significantly lower in the optic chiasm and tracts (p?=?0.0496 and 0.0052, respectively) with late but not early reservoir placement. In the internal capsule, FA in both reservoir groups increased significantly with age (p?Conclusions All hydrocephalic animals treated with intermittent ventricular reservoir tapping demonstrated progressive ventriculomegaly. Both reservoir groups demonstrated WM integrity loss, with the CC the most vulnerable and the optic system the most resilient.     

Is color-flow duplex a good diagnostic test for detection of isolated calf vein thrombosis in high-risk patients?

Color-flow duplex scanning (CDS) is a good diagnostic test for lower extremity proximal deep vein thrombosis (DVT). This report aims to evaluate the diagnostic accuracy of CDS in detecting isolated calf DVT in two in-hospital populations. A total of 166 patients had routine DVT testing with both CDS and venography: 99 total joint arthroplasty patients and 67 symptomatic in-hospital patients. Isolated calf DVT was noted in 34% of arthroplasty patients and 12% of symptomatic in-hospital patients. Peroneal DVT was most common. The sensitivity, specificity, positive predictive value, and negative predictive value (with 95% confidence interval [CI]) of CDS in detecting isolated calf DVT in the symptomatic in-hospital group was 39% (16%-62%), 98% (94%-99%), 88% (65%-99%), and 81% (71%-91%), respectively. In the arthroplasty patients these values were 13% (3%-23%), 92% (85%-99%), 60% (30%-90%), and 55% (45%-65%), respectively. CDS has a low sensitivity in detecting isolated calf DVT among hospitalized patients and cannot be deemed an effective tool for identifying clots limited to only one or two tibial vessels.     

Achieved negative differential resistance behavior of Si/B-substituted into a C6 chain sandwiched between capped carbon nanotube junctions

Electronic transport properties of a pristine C₆ chain and Si/B-substituted into the C₆ chain sandwiched between two (5, 5) capped carbon nanotube electrodes were investigated through first-principles calculations based on non-equilibrium Green''s functions (NEGF) conjugated with density functional theory (DFT). Si and B substitutions will affect the I–V curve of a pristine C₆ chain. In the I–V characteristics, multi negative differential resistance (NDR) with large peak to valley ratio (PVR) and rectifying actions were observed. The NDR behavior originates from the joining and moving of conduction orbitals inside and outside of the bias window at a certain bias voltage. Furthermore, the assessment of transmission coefficient and distribution of molecular orbitals reveals that the rectifying performance is the result of the asymmetric distribution of the frontier molecular orbitals in the central region and their coupling with the electrodes. Multi NDR behavior of B substitution under very low bias voltage is a unique property of our proposed devices. Moreover, the CNT|C–(B–C)₂–C|CNT molecular device shows a high PVR up to 31.8, which demonstrates that the proposed devices can be useful for molecular switching in nanoelectronic devices.

Multi negative differential resistance (NDR) with large peak to valley ratio (PVR) and rectifying actions were observed for a CNT|C–(B–C)₂–C|CNT molecular device.     

Measurement of the humeral head retroversion angle. A new radiographic method

BACKGROUND: In this study, a simple and reliable radiographic method is described to determine the torsional profile of the humeral head. METHODS: First, by using a specially developed frame, the humeral head retroversion angles (HRAs) of 20 dry humeri were measured by an anatomist and an orthopedist. Then the HRA of these humeri were measured by two orthopedists on radiographs taken in semi-axial view when the humeri were in 20 degrees abduction. RESULTS: The results were assessed with the SPSS 9.05 program, and the repeatability coefficient of both methods was 98%. The average difference in angle determination between the two methods was 0.9 degrees; the maximum difference was 3 degrees. After that, posteroanterior semi-axial radiographs of both humerus bones of 40 healthy volunteers were taken by positioning their arms in 20 degrees abduction to the X-ray axis. The mean HRA difference between the right and left sides was 0.4 degrees (maximum difference 3 degrees ) and is of no clinical significance. It was determined that left and right HRAs can be taken as a reference to each other. For measurement of the HRA in the planning of proximal humeral rotation osteotomy and prosthesis replacement arthroplasty, the presented radiographic method can be used with a high rate of accuracy.     

Micro-domains of AQP0 in lens equatorial fibers

To understand why the water channel aquaporin-0 (AQP0) replaces aquaporin-1(AQP1) during lens development, we studied its spatial arrangement and interactions with proteins in the plasma membrane of equatorial fibers. We used freeze-fracture-labelling; a method that can identify the individual intramembrane particle representing the AQP0 channel. We found that AQP0 was arranged in micro-domains that extended along the long axis of the equatorial fiber cell. One micro-domain consisted of AQP0 channels intermingled with the normal complement of integral proteins of the fiber plasma membrane. We found that the density of AQP0 channels varied along the long axis of the fiber. At the apical end of the fiber, the density was barely above background noise (approximately 50 microm(-2)). It increased first to 345=109 microm(-2) and then to 719+/-35 microm(-2) in the region of the plasma membrane facing adjacent fibers (the lateral surface). Another micro-domain, located at the apical end of the fiber, was composed of AQP0 channels within gap junctions ('mixed' junctions). This micro-domain contained approximately 1.5 x 10(5) cell-to-cell channels and approximately 3500 AQP0 channels. A third micro-domain, located exclusively in the lateral surface of the fiber, was composed of clusters of channels abutted against an opposing, particle-free plasma membrane (AQP0 junction). In equatorial fibers, the intramembrane particles in the AQP0 junctions were densely packed (6747+/-1007 microm(-2)), but were not arranged in orthogonal arrays that are characteristic of equaporins. This micro-domain occupied 20-25% of the lateral surface of equatorial fibers and, more importantly, it was arranged in 'ribbons' that extended for long stretches (30-40 microm) along the apical-basal axis. We concluded that the ability of AQP0 to arrange itself in micro-domains conferred functional properties that might contribute to the maintenance of lens transparency and homeostasis.     

Retinacular band excision improves outcome in treatment of plica syndrome

Mild symptoms usually continue after excision of the medial patellar plica. We noticed that the palpable tender cord, located on the anteromedial aspect of the knee in patients with plica syndrome, did not disappear completely after excision of the synovial fold. Beneath all plicae, a retinacular band was visible, and only after excisions of this band did the cord become impalpable. We conducted a study to determine the role of these medial retinacular bands in the symptomatology of the disorder. Twenty-four knees of 22 patients diagnosed with medial patellar plica syndrome were divided into two groups. In the first group, arthroscopic excision of the synovial plica was performed. In the second group, retinacular bands beneath the plica were additionally excised. When Lysholm scores were compared, we found that the second group showed significantly greater improvement. We believe that the retinacular bands play a role in the symptomatology and the pathophysiology of plica syndrome and that excision improves the outcome.

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Résumé Habituellement des symptômes discrets persistent après excision du plica médiopatellaire. Nous avons constaté que le cordon palpable présent dans la partie antéromédiale du genou chez les malades avec un syndrome de plica na pas complètement disparu après excision du repli synovial. Sous tous les plicas une bande retinaculaire était visible et seulement après excision de cette bande le cordon est devenu impalpable. Nous avons conduit une étude pour déterminer le rôle de ces bandes rétinaculaire médiales dans la symptomatologie persistante. Vingt-quatre genoux de 22 malades présentant un syndrome du plica médio patellaire ont été divisés en 2 groupes. Lexcision arthroscopique du plica synovial était faite dans le premier groupe et dans le deuxième groupe la bande rétinaculaire sous le plica a été excisée en plus. Quand les scores de Lysholm ont été comparés nous avons vu que le deuxième groupe avait une meilleure amélioration, statistiquement significative. Nous croyons que cette bande rétinaculaire joue un rôle dans la symptomatologie et la physiopathologie du syndrome du plica et que son excision améliore le résultat.

     

Topographic localization of the motor branch of the median nerve

PURPOSE: To redefine the localization of the thenar branch (TB) of the median nerve in relation to the surface landmarks that are in routine use. METHODS: The study was performed in 37 hands of 34 patients who had carpal tunnel release. All of the patients were women and the mean age was 50 years (range, 35-67 y). A radiologic marking technique was used to determine the localization of the TB, the middle finger radial side line, and Kaplan's cardinal line. The TB was marked by circumscribing with a soft radiopaque yarn and the surface landmark lines were shown by taping a K-wire to the hand for each line. An image-intensifier-printed image was obtained for each case and the distances between the markers of the TB and the wires were measured. RESULTS: The TB had a mean ulnar offset of 12.6 mm (range, 4.0-19.7 mm) from the middle finger radial side line and was located 4.4 mm (range, 0-9.5 mm) proximal to the cardinal line. CONCLUSIONS: During carpal tunnel release surgery the surgeon must pay more attention to the localization of the TB of the median nerve because it was found to be 12.6 mm more ulnar than the location described in the literature.     

Young women presenting with chronic mesenteric ischemia--two case reports

Chronic mesenteric ischemia is primarily a disease of the elderly, who have widespread atherosclerosis of the celiac, superior mesenteric, and inferior mesenteric arteries. Risk factors include smoking, vasculitis, fibromuscular dysplasia, and arterial dissection. Presented here are 2 cases of women under age 50 years burdened with this condition, owing primarily to advanced arteriosclerosis. These cases illustrate a need for increased awareness of mesenteric ischemia as a cause for postprandial abdominal pain in young patients with other stigmata of advanced arterial occlusive disease.