Restoration Of Amplitude Research Articles

Dual mobility total hip arthroplasty in complex cases

Since their launch on the market in the late 1970s, Dual Mobility Cups (DMCs) have shown encouraging results both in terms of stability and of restoration of wide hip joint amplitude. Therefore, the use of DMCs is mainly indicated for patients at risk of dislocation, such as those with neuro-muscular diseases, femoral neck fractures, or complex situations like failed hip osteosynthesis, as well as being indicated in the setting of revisions.The objective of this review is to provide indications and recommendations for orthopedic surgeons using DMCs in complex primary and revision settings. An overview of the tech- nical and theoretical requirements necessary to achieve a successful DMC implantation is presented. According to the literature, indications have been expanded thanks to the constant improvement and development of materials and implants. Nowadays, the use of DMCs is no longer limited to revision surgery alone; on the contrary, increasingly complex cases may be approached. Long-term studies are needed before any formal conclusions can be drawn an before the promising results that have been obtained in difficult cases are consolidated.

Vibratory function and healing outcomes after small intestinal submucosa biomaterial implantation for chronic vocal fold scar.

Vocal fold scar is a major cause of dysphonia, and optimal treatments do not currently exist. Small intestinal submucosa (SIS) is a biomaterial developed for the treatment of a variety of pathologies. The purpose of this study was to investigate the effects of SIS implantation on tissue remodeling in scarred vocal folds using routine staining, immunohistochemistry, and high-speed videoendoscopy (HSV). Prospective, blinded group analysis. Thirteen New Zealand White rabbits underwent a vocal fold scarring procedure followed by microflap elevation with or without SIS implantation. Seven months later, they underwent a phonation procedure with HSV and laryngeal harvest. Alcian blue and elastica van Gieson staining and immunohistochemistry for collagen types I and III were used to evaluate histological healing outcomes. Dynamic functional remodeling of the scarred vocal fold in the presence of SIS implants was evaluated using HSV imaging to capture restoration of vibratory amplitude, amplitude ratio, and left-right phase symmetry. Density of collagen I was significantly decreased in SIS versus microflap-treated vocal folds. No differences were found between groups for hyaluronic acid, elastin, or collagen type III. Organization of elastin in the subepithelial region appeared to affect amplitude of vibration and the shape of the vocal fold edge. SIS implantation into chronic scar reduced the density of collagen I deposits. There was no evidence of a negative impact or complication from SIS implantation. Regardless of treatment type, organization of elastin in the subepithelial region may be important to vibratory outcomes. NA. Laryngoscope, 128:901-908, 2018.

Recovery of vibratory function after vocal fold microflap in a rabbit model

The purpose of this study was to evaluate the return of vibratory function and restoration of vibration amplitude and symmetry after vocal fold microflap surgery. Prospective in vivo animal model. Microflap surgery was performed on 30 New Zealand white breeder rabbits. The left vocal fold received a 3-mm epithelial incision and mucosal elevation, while the contralateral vocal fold was left intact to serve as an internal control. Quantitative analysis of amplitude ratio and lateral phase difference were measured using high-speed laryngeal imaging at a frame rate of 10,000 frames per second from animals undergoing evoked phonation on postoperative days 0, 1, 3, 5, and 7. Quantitative measures revealed a significantly reduced amplitude ratio and lateral phase difference on day 0 after microflap. These impairments of vibratory function on day 0 were associated with separation of the vocal fold's body-cover layer. Amplitude ratio increased significantly by day 3 after microflap, with further increases in vibration amplitude on days 5 and 7. While the amplitude ratio improved significantly on day 3, lateral phase difference decreased significantly on day 3, and returned to normal on days 5 and 7. High-speed laryngeal imaging was used to investigate the natural time course of postmicroflap recovery of vibratory function. Results revealed the restoration of vibration amplitude and lateral phase difference by days 3 to 7 after microflap. The time period of improved vibratory function observed in this study coincides with the end of the well-documented inflammatory phase of vocal fold wound repair. N/A.

The influence of age on the recovery of the ERG photostress test

Focal ERG associated with photostress test could be a useful diagnostic method for evaluating macular visual function. The main aim of this study was to evaluate the effect of age on the recovery time constant of the ERG photostress test. The second aim was to assess the sources of variability which affect the measurements. Fifty-four healthy subjects (108 eyes), aged between 21 and 77, with corrected VA of 20/20 or more and absence of any ocular or systemic disease, were recruited. For each eye ERG response to focal (20° in diameter) 42-Hz stimulation was recorded: three series of 200 summations in base conditions and a six series of 42-Hz ERGs (100 summations each) at 10, 40, 80, 180, 300 and 420 s after bleaching by a white spot of light (20° in diameter) from a direct ophthalmoscope (800 cd/m²) pointed at macular region for 30 s. Fourier analysis was performed and amplitude of the first harmonica calculated. The relationship of basal amplitudes with subject age and gender, and the kinetics of macular function recovery were assessed through mixed-effects models. Mean basal amplitude decreases by 0.046 μV for year of life. The recovery after bleaching is proportional to age with an increase of 4.31 s for decade. Restoration of amplitude is slower in older subjects. There is a significant decrease in macular ERG amplitude with age. The macular recovery after photostress shows exponential kinetics that are less efficient in older subjects: this could be related to lower effectiveness of photopigment restoration in advanced age.

The vesicle cycle in motor nerve endings of the mouse diaphragm

Experiments on the mouse diaphragm muscle using intracellular microelectrode recordings and fluorescence microscopy were performed to study the dynamics of transmitter secretion and synaptic vesicle recycling processes (the exocytosis-endocytosis cycle) in motor nerve endings (NE) during prolonged rhythmic stimulation (20 impulses/sec). During stimulation, there were triphasic changes in the amplitude of endplate potentials (EPP): an initial rapid reduction, followed by prolonged (1-2 min) stabilization of amplitude, i.e., a plateau, and then a further slow decrease. Restoration of EPP amplitude after stimulation for 3 min occurred over a period of several seconds. Loading of synaptic vesicles with the fluorescent endocytic stain FM1-43 showed that rhythmic stimulation led to a gradual (over 5-6 min) decrease in NE fluorescence, demonstrating exocytosis of synaptic vesicles. Quantum analysis of the electrophysiological data and comparison of these data with results from fluorescence studies suggested that mouse NE have a high rate of endocytosis and reutilization of synaptic vesicles (the mean recycling time was about 50 sec), which may support the maintenance of reliable synaptic transmission during prolonged high-frequency activity. The sizes of the release-ready and recycling pools of synaptic vesicles were determined quantitatively. It is suggested that vesicle recycling in mouse NE occurs via a short, rapid pathway with incorporation into the recycling pool. Vesicles of the reserve pool are not used for transmitter secretion in the stimulation conditions used here.

Electroacupuncture may relax the sphincter of Oddi in humans

Background: This study was designed to evaluate the effects of electroacupuncture on sphincter of Oddi (SO) motility in humans and to associate the manometric findings with cholecystokinin (CCK) plasma levels. Methods: Eleven patients (M:F = 5:6) with various kinds of biliary disorders were enrolled. SO motility was monitored with conventional low-compliance, continuous perfusion technique at ERCP (n = 9) or via percutaneous transhepatic cholangioscopy (n = 2). After baseline monitoring for phasic wave contractions of SO, electroacupuncture was applied at a specific acupoint GB 34. A nonspecific acupoint 5 cm away from GB 34 was selected as a control. Manometric parameters of the SO were also measured in 6 subjects during stimulation of the control acupoint. CCK plasma levels were measured during electroacupuncture stimulation. Results: All manometric parameters including basal pressure, amplitude, frequency, and duration of phasic wave contractions of the SO were significantly decreased (p < 0.05) during electroacupuncture stimulation. The inhibition of SO contractility was accompanied by increased CCK plasma levels. After discontinuation of electroacupuncture stimulation, restoration of amplitude and duration to basal conditions was noted. A tendency toward return of SO basal pressure and contractile frequency to baseline was also observed. Stimulation of the control acupoint did not affect SO contractility. Conclusion: Electroacupuncture stimulation of acupoint GB 34 resulted in reversible inhibition of SO contraction in humans. The response of SO to electroacupuncture stimulation may be mediated by some neurohormonal mechanisms including CCK release.

Direct restoration of light amplitude and phase by the reproduced structure of intensity in the Talbot effect

We suggest a technology for restoration of light-beam amplitude and phase on the basis of the Talbot effect. As a result of numerical investigations we found that the determining role in the restoration of fronts is played by the magnitudes of the spreads of the phase front. When the spreads of the phase do not exceed a certain limit, independent highly accurate restoration of both fronts is possible. Admissible limits of the change in the spreads of each of the fronts are determined numerically. Exceeding of these values leads to a sharp decrease in the accuracy of restoration of phase and amplitude.

Waveform response to the morphology of 2-D subducted slabs

Summary To evaluate waveform responses to morphological variations of the subducted lithospheric slab, scalar waveform solutions are computed for 2-D slab models perpendicular to the arc. The dependence of the waveforms on the background 1-D velocity model and on the wavelet frequency is analysed. The waveform variation due to the background velocity model is characterized by gradual changes in amplitude and traveltime over the take-off angle; such variation can be distinguished from the slab-generated waveform anomaly, which is restricted to a narrow take-off angle range and often severely alters the wavelet frequency. Therefore, much information can be gained through the waveform modelling of slabs in a homogeneous background velocity model. The characteristics of the waveform anomaly, such as slab-diffracted waveform broadening, depend on the ratio between the wavelength of the main source wavelet and the thickness of the slab. The slab-diffracted broadening, which has low-frequency characteristics, may be described more accurately as a wavelet broadening rather than a pulse-width broadening. When the wavelength is shorter than about one-half of the slab's thickness, a restoration of normal amplitude that is accompanied by waveform distortion is observed for waves propagating parallel and down-dip to the slab. Considerable waveform variations in arrival time, amplitude and wavelet-width exist among different morphological models of the slab, and may provide some useful guidance in inferring the real slab morphology from waveform data.

Physiological consequences of antiserum-mediated experimental demyelination in CNS.

To study the pathophysiology of immunologically mediated demyelination in the central nervous system (CNS), we injected 20 to 30 microliters of polyclonal antigalactocerebroside serum (AGC) into the lower thoracic dorsal column of the spinal cord in 20 Wistar rats. AGC-injected spinal cords contained areas of fascicular demyelination adjacent to the focus of axonal degeneration at the injection site. Somatosensory evoked potentials were recorded serially after tibial nerve stimulation. In 85% of AGC-injected animals, the following characteristics were observed by 3 days after injection: (1) decreased amplitude of the cortically generated potential (P15); (2) failure of transmission of high-frequency (50 Hz) impulses (rate-dependent block); (3) delayed conduction velocity of the compound action potentials through the lesion. None of these changes was seen in 90% of 20 rats injected with normal saline or control rabbit sera. In 7 rats with acrylamide-induced axonopathy or wallerian degeneration, the rate-dependent block was not observed. The onset of clinical symptoms (hindlimb ataxia) in AGC-injected rats was best correlated with development of the rate-dependent block. Clinical recovery was observed by 14 days after injection concurrent with restoration of P15 amplitude, when the rate-dependent block and decreased conduction velocities were unchanged. High-frequency-resistant conduction was re-established much later than clinical recovery in 3 rats. These findings suggest that failure of high-frequency impulse transmission may produce clinical symptoms and that a central adaptive mechanism to remodulated trains of impulses plays a role in clinical recovery from CNS demyelination.

Electrophysiological evidence of peripheral nerve dysfunction in six dogs with botulism type C

In six dogs with botulism type C electrophysiological examinations showed: fibrillation potentials and prolonged insertional activity; low amplitude of the evoked muscle action potential; decrease in amplitude of the compound muscle action potential with slow repetitive stimulation; slowing of motor and sensory velocities in the peripheral nerve; and restoration of velocity and amplitude corresponding to clinical improvement. These findings indicate peripheral nerve dysfunction which cannot be explained adequately by current knowledge of the action of botulinum toxin on cholinergic nerve endings. It is therefore suggested that botulinum toxin also interferes with peripheral nerve conduction.

Using the on‐effect to investigate an input‐dependent critical bandwidth

The on‐effect is the perceptual enhancement of one pure‐tone component of a multitone stimulus, created by an “amplitude notch” (abrupt reduction and restoration of amplitude) in the tone. Below a critical frequency separation (CFS) of components, the on‐effect is lost. This study investigated the relationship between the CFS for the on‐effect and the critical bandwidth (CBW) established in masking experiments. Subjects identified the direction of a series of amplitude notches in ascending or descending components of a multitone stimulus. Tones were spaced at fifteen levels of percent of CBW (65%–100%). When stimuli were adjusted for equal loudness, the CFS for on‐effect detection was a constant percentage of CBW in the range tested (100–4000 Hz). Furthermore, the CFS varied directly with loudness, i.e., the louder the stimulus the greater the CFS. These results suggest that the CBW depends on input intensity as well as input frequency. Whitfield [I. C. Whitfield, “The Neural Code,” in Handbook of Perception, edited by E. C. Carterette and M.P. Friedman (Academic Press, New York, 1978), Vol. IV] proposed a physiological model of pitch and intensity encoding consistent with these data.