The acoustically evoked short latency negative response (ASNR) in a unilaterally deaf cat with histologically-confirmed cochleosaccular degeneration

BACKGROUND: A negative potential is occasionally recorded in humans and animals with profound deafness during brainstem auditory evoked potential (BAER) tests if loud intensities are used. This acoustically evoked short latency negative response (ASNR) is hypothesized to be of saccular origin. The sensitivity to sound of vestibular end organs is also used to produce vestibular evoked myogenic potentials (VEMP), a test that evaluates vestibular function. The same saccular origin is accepted also for VEMP. CASE PRESENTATION: A neutered male white domestic short hair cat presented with profound deafness and an ASNR in the left ear during BAER test performed when he was 8 months old. BAER tracings were substantially unchanged at the age of 12 years, immediately before euthanasia that was requested by the owner for the presence of an unrelated neoplastic disorder. The cat underwent a complete post-mortem necropsy including histopathology of the middle and inner ears. Histopathologic results confirmed the presence of a cochleosaccular degeneration of the left ear while the cochlea and sacculus of the right ear and the utriculus and semicircular canals of both ears were histologically normal. CONCLUSIONS: This case report describes the auditory and histopathologic findings of a cat that showed an ASNR during BAER test despite the presence of cochleosaccular deafness. These results confirm that a saccular origin for the ASNR in this case, and in general in cats and dogs with congenital deafness associated with white pigmentation, is improbable. The hypothesis that the sacculus is the vestibular end organ responsible for the generation of the ASNR and VEMP in humans comes mainly from animal studies. The findings in this report may change the clinical interpretation of the results of BAER and VEMP not only in companion animals, but in humans as well

Spectral properties of a 2D scalar wave equation with 1D-periodic coefficients: application to SH elastic waves

The paper provides a rigorous analysis of the dispersion spectrum of SH (shear horizontal) elastic waves in periodically stratified solids. The problem consists of an ordinary differential wave equation with periodic coefficients, which involves two free parameters $\omega$ (the frequency) and $k$ (the wavenumber in the direction orthogonal to the axis of periodicity). Solutions of this equation satisfy a quasi-periodic boundary condition which yields the Floquet parameter $K$. The resulting dispersion surface $\omega (K,k)$ may be characterized through its cuts at constant values of $K, k$ and $\omega$ that define the passband (real $K$) and stopband areas, the Floquet branches and the isofrequency curves, respectively. The paper combines complementary approaches based on eigenvalue problems and on the monodromy matrix $\mathbf{M}$. The pivotal object is the Lyapunov function $\Delta (\omega ^{2},k^{2}) \equiv 1/2\mathrm{trace}\mathbf{M}=\cos K$ which is generalized as a function of two variables. Its analytical properties, asymptotics and bounds are examined and an explicit form of its derivatives obtained. Attention is given to the special case of a zero-width stopband. These ingredients are used to analyze the cuts of the surface $\omega (K,k).$ The derivatives of the functions $\omega (k)$ at fixed $K$ and $\omega (K)$ at fixed $k$ and of the function $K(k)$ at fixed $\omega$ are described in detail. The curves $\omega (k)$ at fixed $K$ are shown to be monotonic for real $K,$ while they may be looped for complex $K$ (i.e. in the stopband areas). The convexity of the closed (first) real isofrequency curve $K(k)$ is proved thus ruling out low-frequency caustics of group velocity. The results are relevant to the broad area of applicability of ordinary differential equation for scalar waves in 1D phononic (solid or fluid) and photonic crystals.Comment: 35 pages, 4 figure

Circadian Activity of Topical 0.05% Betamethasone Dipropionate in Human Skin In Vivo

The influence of treatment duration, vehicle, and time of day of application on topical 0.05% betamethasone dipropionate uptake into human stratum corneum and the resulting skin- blanching response was investigated in human subjects. Drug uptake into stratum corneum and the resulting skin color changes measured with a chromameter demonstrate an equilibrium delay. Maximal drug uptake occurred at 2 h, whereas maximal skin color changes occurred 6h after a single application. Extent of decreased skin color was dependent on vehicle, treatment duration, and time of day of application. Time of maximal decreased skin color occurred at midnight independent of vehicle, treatment duration, or time of day of application. This time of maximal drug activity coincides with the well-known time period of lowest circulating cortisol concentrations (2000-0400 h). Application of a single 2- or 6-h dose of the 0.05% cream at 1600h produced more extensive and prolonged changes in skin color over 24h than a 0900-h application in the same subject. These data demonstrate that the extent and duration of topical corticosteroid activity in human skin is influenced by vehicle, treatment duration, and time of day of application. The prolonged changes in skin color measured with a single dose applied at 1600h suggest that a once-a-day dosing regimen in the late afternoon may be sufficient for dermatologic therapy. Elucidation of these circadian responses with topical corticosteroids may provide a rational basis for the future re-evaluation of the appropriate therapeutic regimen with this class of drugs in dermatologic medicine

Necrotiserende encefalitis bij de yorkshire terriër: a retrospective study (1990-2008)

In this retrospective study thirteen Yorkshire terriers with histopathologically confirmed necrotizing encephalitis were studied All the dogs had progressive neurologic symptoms compatible with a cerebral or a brainstem disease The blood work revealed increased creatinine kinase (CK) levels in most cases The cerebrospinal fluid analysis was characterized by elevated protein concentrations and mononuclear pleocytosis Computed tomography (CT) scans revealed hypodense areas, ventriculomegaly and contrast enhancement All thirteen Yorkshire terriers were euthanized due to the progressive course of this brain disease and the lack of an effective treatment

On the effective shear speed in 2D phononic crystals

The quasistatic limit of the antiplane shear-wave speed ('effective speed') $c$ in 2D periodic lattices is studied. Two new closed-form estimates of $c$ are derived by employing two different analytical approaches. The first proceeds from a standard background of the plane wave expansion (PWE). The second is a new approach, which resides in $\mathbf{x}$-space and centers on the monodromy matrix (MM) introduced in the 2D case as the multiplicative integral, taken in one coordinate, of a matrix with components being the operators with respect to the other coordinate. On the numerical side, an efficient PWE-based scheme for computing $c$ is proposed and implemented. The analytical and numerical findings are applied to several examples of 2D square lattices with two and three high-contrast components, for which the new PWE and MM estimates are compared with the numerical data and with some known approximations. It is demonstrated that the PWE estimate is most efficient in the case of densely packed stiff inclusions, especially when they form a symmetric lattice, while in general it is the MM estimate that provides the best overall fitting accuracy.Comment: 13 pages, 9 figure

Disruption of information processing in schizophrenia: The time perspective

AbstractWe review studies suggesting time disorders on both automatic and subjective levels in patients with schizophrenia. Patients have difficulty explicitly discriminating between simultaneous and asynchronous events, and ordering events in time. We discuss the relationship between these difficulties and impairments on a more elementary level. We showed that for undetectable stimulus onset asynchronies below 20ms, neither patients nor controls merge events in time, as previously believed. On the contrary, subjects implicitly distinguish between events even when evaluating them to be simultaneous. Furthermore, controls privilege the last stimulus, whereas patients seem to stay stuck on the first stimulus when asynchronies are sub-threshold. Combining previous results shows this to be true for patients even for asynchronies as short as 8ms. Moreover, this peculiarity predicts difficulties with detecting asynchronies longer than 50ms, suggesting an impact on the conscious ability to time events. Difficulties on the subjective level are also correlated with clinical disorganization. The results are interpreted within the framework of predictive coding which can account for an implicit ability to update events. These results complement a range of other results, by suggesting a difficulty with binding information in time as well as space, and by showing that information processing lacks continuity and stability in patients. The time perspective may help bridge the gap between cognitive impairments and clinical symptoms, by showing how the innermost structure of thought and experience is disrupted