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Schelkunoff's method, also commonly refered to as Coupled Mode Method (CMM), is a numerical method which gives the propagation constants and the electromagnetic field in a general homogeneous medium bounded by perfect electric walls. In this paper, we test Schelkunoff's method for a waveguide filled with an isotropic chiral material (chirowaveguide) where the dimensions of the walls are electrically large compared with the wavelength. It is reasonable to foresee that, in this case, the results given by Schelkunoff's method must approach to the corresponding ones for the chiral unbounded medium. Effectively, we obtain the solutions for both circular polarized waves (right-handed and left-handed) in free propagation in a single calculation. These results are in opposition with those of other authors analyzing analogous cases. [ABSTRACT FROM AUTHOR]

Neurotrophins (NTs) and their signal transducing Trk receptors play a critical role in the development and maintenance of specific neuronal populations in the nervous system of higher vertebrates. They are responsible for the innervation of the inner ear cochlear and vestibular sensory epithelia. Neurotrophins and Trks are also present in teleosts but their distribution in the inner ear is unknown. Thus, in the present study, we used Western-blot analysis and immunohistochemistry to investigate the expression and cell localization of both NTs and Trk receptors in the inner ear of alevins of Salmo salar and Salmo trutta. Western-blot analysis revealed the occurrence of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), but not nerve growth factor (NGF), as well as all three Trk receptors, i.e. TrkA, TrkB and TrkC, the estimated molecular weights of which were similar to those expected for mammals. Specific immunoreactivity for neurotrophins was detected mainly in the sensory epithelia. In particular, BDNF immunoreactivity was found in the maculae of the utricle and saccule, whereas NT-3 immunoreactivity was present in the sensory epithelium of the cristae ampullaris. As a rule the sensory epithelia of the inner ear lacked immunoreactivity for Trks, thus excluding possible mechanisms of autocrinia and/or paracrinia. By contrast, overlapping subpopulations of neurons in the statoacoustic ganglion expressed TrkA (about 15%), TrkB (about 65%) and TrkC (about 45%). The present results demonstrate that, as in mammals and birds, the inner ear of teleosts expresses the components of the neurotrophin–Trk system, but their roles remain to be elucidated. [ABSTRACT FROM AUTHOR]

Background: The Peptide YY (PYY) secretion pattern was assessed in morbidly obese (MO) patients before and after vertical banded gastroplasty (VBG). Methods: 12 MO patients (10 women, 2 men) age 29-62 years, BMI 50.7 ± 9.6 kg/m2, treated with a VBG were studied. Before surgery, blood samples were taken in basal conditions of fasting and 10, 15, 20, 30 and 60 min after the ingestion of a semiliquid test meal. This was repeated in the same patients 6 and 12 months after VBG. Blood samples were also taken from 6 healthy non-obese subjects as controls. PYY plasma concentration was measured by radioimmunoassay with I125. Results: There were statistically significant differences between the preoperative PYY concentration in MO patients compared to controls. After a VBG, PYY concentration varied significantly compared to the preoperative levels.There was no significant difference between the PYY concentrations in the MO patients after VBG and the controls. Conclusion: PYY concentration is lower in MO patients compared with non-obese. After VBG, PYY concentration gradually rises to the control levels. [ABSTRACT FROM AUTHOR]

The TLM method, being a time domain method, cannot deal directly with frequency dispersive media. A way for modelling such media, for instance, dielectric dispersive ones, is proposed, starting from the causality relationship between field vectors D and E, which is discretized over the same space–time mesh as the three-dimensional TLM mesh (in our case, with HSCN node). This leads to adding, at each node on the network, three voltage sources (one for each field component), their value depending on the previous instants. The method is validated by computing the reflection (magnitude and phase) coefficient at normal incidence at an air–dielectric interface, for different dispersive behaviours of the dielectrics. Copyright © 2001 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The role of protein kinase C (PKC). during the early development of the inner ear was investigated using organ culture techniques. Otocysts isolated from chick embryos were made quiescent by culturing in the absence of serum for 24 h. The normal process of development could be reactivated by restoration of serum and other growth factors. Addition of phorbol ester (TPA) or synthetic diacylglycerol (OAG) to serum-free medium was also effective in reactivating development and stimulation of DNA synthesis was 41% and 52% of that of serum, respectively. Insulin potentiated the effects of TPA and OAG but had no effect when present alone. Morphogenesis and the associated cell proliferation stimulated by either serum or PKC activation were both inhibited by sphingosine, an in vitro inhibitor of PKC. Inhibition by sphingosine was dose-dependent with a half-maximal inhibitory concentration of about 10 μM. The results suggest that PKC activation is an essential step in controlling proliferative growth during early stages of the development of the inner ear. [ABSTRACT FROM AUTHOR]

Microtubule-associated proteins (MAPs) are essential cytoskeletal components during development for neurogenesis and neuronal plasticity. Inner ear innervation is accomplished by cochleovestibular ganglion (CVG) neurons in a highly specific, well-defined pattern, which is regulated by neurotrophic factors belonging to the neurotrophin family. The inner ear offers a suitable model for studying the expression of MAPs and assessing their role in neurotrophin-induced effects that are required for neuron-target innervation. The present study was undertaken to analyze the expression and localization of MAP5 isoforms during development of CVG neurons in vivo and in vitro; as well as the regulation of MAP5 by neurotrophin-3 (NT3) in cell culture. MAP5 expression in the inner ear of chick embryos and postnatal specimens was monitored using immunoblots and immunohistochemistry on frozen sections. MAP5 was highly expressed during the early stages of CVG development, at embryonic day (E)4, being located in both neuronal perikarya and neurites. Expression was maintained during the neurite outgrowth phase (E6–E12), when strong MAP5 immunostaining was observed at the same cellular locations. MAP5 expression decreased suddenly at E14, after the establishment of specific connections between the CVG neurons and their targets, the sensory epithelium of the inner ear. In cultured CVG neurons addition of NT3 led to increased MAP5 expression and produced neurite outgrowth. Both effects are differentially regulated in parallel by low (0.5 ng/ml) and high (5 ng/ml) NT3 concentrations. Present results suggest that MAP5 may be involved in neurotrophin-induced microtubule bundling during neurite outgrowth of auditory neurons. [ABSTRACT FROM AUTHOR]

Previous studies of the early development of the neural tube have shown the existence of an intraneural fluid, which causes a positive pressure inside this primordium, and seems to play a key role in the early development of the central nervous system. In the present study we investigated the composition and synthesis of this intraneural fluid. By using a sequential method, which includes fixation with glutaraldehyde plus cetylpyridinium chloride, opening the neural cavity after critical point drying and scanning electron microscopy analysis, we found a water-soluble extracellular matrix that filled up the brain vesicles of chick embryos at the earliest stages of the neural tube. An ultrastructural study of the neural epithelium during these stages revealed the existence of a secretion process in the neural cells toward the apical side, the future neural cavity. An immunocytochemical study to asses the nature of the secreted material has shown that the intraneural matrix contains chondroitin sulphate proteoglycan, which appeared homogenously distributed throughout the neural cavity. Our findings demonstrate that the intraneural liquid is a fluid of complex composition and includes chondroitin sulphate proteoglycan as an osmotically active molecule. This suggests a morphogenetic role for the proteoglycan during early brain enlargement. The neural ectoderm is a polarized epithelium from early developmental stages and secretes the intraneural matrix. [ABSTRACT FROM AUTHOR]

Laparoscopic abdominal surgery is considered a low-risk procedure for postoperative thromboembolic disease. We report two cases of pulmonary embolism following laparoscopic cholecystectomy, review the incidence of deep venous thrombosis and pulmonary embolism in laparoscopic cholecystectomy, and suggest a specific prophylactic scheme for patients undergoing laparoscopic cholecystectomy. In spite of the low incidence of postoperative thromboembolic disease following minimally invasive procedures, the risk of pulmonary embolism must not be underestimated and its symptoms must not be underdiagnosed. [ABSTRACT FROM AUTHOR]

Laparoscopic abdominal surgery is considered a low-risk procedure for postoperative thromboembolic disease. We report two cases of pulmonary embolism following laparoscopic cholecystectomy, review the incidence of deep venous thrombosis and pulmonary embolism in laparoscopic cholecystectomy, and suggest a specific prophylactic scheme for patients undergoing laparoscopic cholecystectomy. In spite of the low incidence of postoperative thromboembolic disease following minimally invasive procedures, the risk of pulmonary embolism must not be underestimated and its symptoms must not be underdiagnosed. [ABSTRACT FROM AUTHOR]

This letter describes a two-dimensional (2-D) extension of a recently developed finite-difference time-domain (FDTD) scheme to model wave propagation in bi-isotropic media. To our knowledge this method is the only one successfully generalized to modeling transient microwave signals in general lossy dispersive bi-isotropic media. The new 2-D cell built and computational procedure of the FDTD algorithm developed is described. Condon and Lorentz dispersion models have been included for modeling the frequency dependence of the medium parameters and the auxiliary differential equation (ADE) method is considered to deal with dispersion in order to avoid defining complex back-stored numbers to compute the convolutions recursively. Finally the oblique incidence of a wave on a chiral medium and the propagation in a general lossy bi-isotropic medium have been successfully simulated. [ABSTRACT FROM PUBLISHER]

Shows that the formation of the otic vesicle is inhibited by antisense oligonucleotides targeted to be the secreted form of int-2, and by antibodies against int-2 oncoproteins. Also shows that basic fibroblast growth factor (bFGF) can mimic the inductive signal in the absence of the rhombencephalon.

Presents a letter to the editor related to the far zone scattering calculation of frequency -department material objects.

A time-domain solution of electromagnetic wave propagation in Tellegen materials is presented. The angle tilt between electric and magnetic fields, the phase speed of the wave, and the intrinsic impedance are computed when the medium is excited with a monochromatic source. The results are in good agreement with theoretical predictions. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 167–168, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11004 [ABSTRACT FROM AUTHOR]