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[en] A woodpecker is known to drum the hard woody surface of a tree at a rate of 18 to 22 times per second with a deceleration of 1200 g, yet with no sign of blackout or brain damage. As a model in nature, a woodpecker is studied to find clues to develop a shock-absorbing system for micromachined devices. Its advanced shock-absorbing mechanism, which cannot be explained merely by allometric scaling, is analyzed in terms of endoskeletal structures. In this analysis, the head structures (beak, hyoid, spongy bone, and skull bone with cerebrospinal fluid) of the golden-fronted woodpecker, Melanerpes aurifrons, are explored with x-ray computed tomography images, and their shock-absorbing mechanism is analyzed with a mechanical vibration model and an empirical method. Based on these analyses, a new shock-absorbing system is designed to protect commercial micromachined devices from unwanted high-g and high-frequency mechanical excitations. The new shock-absorbing system consists of close-packed microglasses within two metal enclosures and a viscoelastic layer fastened by steel bolts, which are biologically inspired from a spongy bone contained within a skull bone encompassed with the hyoid of a woodpecker. In the experimental characterizations using a 60 mm smoothbore air-gun, this bio-inspired shock-absorbing system shows a failure rate of 0.7% for the commercial micromachined devices at 60 000 g, whereas a conventional hard-resin method yields a failure rate of 26.4%, thus verifying remarkable improvement in the g-force tolerance of the commercial micromachined devices.
[en] Skull-base cephalocoeles and cerebrospinal fluid (CSF) leaks may be congenital, spontaneous, or secondary. A classification of congenital lesions is formulated and the imaging features are illustrated. The concept of spontaneous skull-base CSF leaks and the significance of aberrant arachnoid granulations in imaging these patients are explored. The majority of secondary lesions relate to trauma; however, other potential causes of secondary skull-base cephalocoeles and CSF leaks are discussed. Imaging evaluation in these clinical scenarios may be complex and the role of each imaging method is reviewed.
[en] We present two patients with hypocaeruloplasminaemia and a heteroallelic caeruloplasmin gene mutation (HypoCPGM). These patients had diabetes mellitus and tremor of the hands, respectively. T2-weighted fast spin-echo MRI showed mildly reduced intensity of the putamen, much more marked on echo-planar imaging. (orig.) (orig.)
[en] The authors give the results of 65 radioisotopic cisternographies for suspected rhinorrheas in frontal basal head injuries. Indium 111-DTPA lombar injection allows the investigation at least for 48 hours. After localizing the CSF fistulae, the gammacisternography permits us to study associated CSF circulation anomalies. Results and discussion give the correlation between positive tests and surgical findings. The best successfull conditions of exploration are enough activity and a fluent clinical leakage of CSF. Nasal cotton pledgets improve the success of the exploration
[fr]Les auteurs presentent les resultats obtenus dans 65 cisternographies radioisotopiques a la recherche de breches osteomeningees de l'etage anterieur. L'injection d'indium 111 DTPA par voie lombaire permet l'exploration du patient pendant 48 heures et peut mettre en evidence, apres la visualisation d'un ecoulement du LCR, les anomalies de circulation associees. La discussion porte sur les criteres de positivite de l'examen scintigraphique et les conditions optimales d'exploration incluant le comptage de meches de coton placees dans les narines et choisissant la periode d'ecoulement pour realiser la gammacisternographie
[en] A 22-year-old woman presented with severe mixed hearing loss and a flow of cerebrospinal fluid in the middle ear during stapes surgery (stapes gusher). HRCT of the temporal bones showed characteristic abnormalities of the inner ear (bulbous dilatation of the lateral portion of the internal acoustic meatus with incomplete separation from the cochlea, and widening of the first part of the facial nerve canal) described in X-linked progressive mixed deafness with stapes gusher. The evaluation of the patient's family revealed a sister with the same clinical history and identical HRCT findings, and 11 normal male relatives. This is the first report with typical findings of this entity that affects only female members of a family, suggesting another type of inheritance
[en] The choroid plexus (ChP) is a non-neural epithelial tissue that produces cerebrospinal fluid (CSF). The ChP differentiates from the roof plate, a dorsal midline structure of the neural tube. However, molecular mechanisms underlying ChP development are poorly understood compared to neural development. MafB is a bZip transcription factor that is known to be expressed in the roof plate. Here we investigated the role of MafB in embryonic development of the hindbrain ChP (hChP) using Mafb-deficient mice. Immunohistochemical analyses revealed that MafB is expressed in the roof plate and early hChP epithelial cells but its expression disappears at a later embryonic stage. We also found that the Mafb-deficient hChP exhibits delayed differentiation and results in hypoplasia compared to the wild-type hChP. Furthermore, the Mafb-deficient hChP exhibits increased apoptotic cell death and decreased proliferating cells at E12.5, an early stage of hChP development. Collectively, our findings reveal that MafB play an important role in promoting hChP development during embryogenesis. - Highlights: • MafB is expressed in the roof plate and the early hindbrain choroid plexus (hChP). • Loss of MafB causes delayed differentiation and hypoplasia of the embryonic hChP. • The Mafb-deficient hChP exhibits increased apoptosis and decreased proliferation.
[en] We present a case of persistent primitive hypoglossal artery (PPHA) associated with Chiari II malformation and discuss the clinical implications. There has been one reported case of PPHA associated with Chiari 1 malformation, but none in association with Chiari II. Our patient also had a widened hypoglossal canal, with cerebrospinal fluid (CSF) sac herniation through it