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PubMed1988

Peripheral antagonistic action of trimebutine and kappa opioid substances on acoustic stress-induced gastric motor inhibition in dogs.

The effects of intracerebroventricular (i.c.v.), intravenous (i.v.) and oral (p.o.) administration of trimebutine on the gastric motor inhibition induced by acoustic stress were investigated in fasted dogs fitted with strain-gauge transducers on the antrum and proximal jejunum. Started 40-50 min after the last migrating motor complex, a 1 h acoustic stress delayed by 111% the occurrence of the next gastric migrating motor complex without affecting the jejunal motor pattern. This inhibition of gastric migrating motor complex induced by acoustic stress was abolished by previous p.o. administration of trimebutine (1 mg/kg) but not by its i.v. (0.1 mg/kg) or i.c.v. (0.01 mg/kg) injection. The trimebutine blockade of gastric motor alterations induced by acoustic stress was suppressed after previous i.v. treatment with MR 2266 (0.3 mg/kg) but was unaffected by naloxone (0.3 mg/kg). Furthermore oral administration of U-50488H (10 micrograms/kg) and ethylketocyclazocine (10 micrograms/kg) respectively abolished and reduced the acoustic stress-induced delay of the occurrence of the gastric migrating motor complex. We concluded that trimebutine is able to antagonize the gastric motor disturbances induced in dogs by acoustic stress, probably by acting selectively on peripheral kappa receptors located in the wall of the proximal gut and directly stimulated from a mucosal site.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1992

Acoustic probe-based ELISA.

The effects of acoustic microstreaming during incubation steps of a prototypical three-step ELISA were studied. Acoustic microstreaming, an orderly mixing of microwell contents induced by linear oscillation of immersible acoustic probes, was shown to be particularly effective when coupled with locating the solid phase on the surface of the probes. Optical densities achieved for acoustic probe-based assays were equivalent to those for uninsonated microwell-based assays with only 20% of the microwell solid phase surface area. Low-level antibody detection was significantly improved and antibody incubation times significantly shortened without loss of signal. Acoustic probe-based assays can enhance assay and laboratory efficiency through testing for multiple analytes in a single sample or increasing available binding surface area (by using probe and well surfaces simultaneously), and by eliminating quenching. Acoustic probe ELISA methodology has significant implications for cost-effective automation.

Acoustics↗

PubMed1995

Clinicopathologic growth factors of acoustic neuromas.

BACKGROUND Understanding the tumor growth rate is very important when considering strategies for the treatment of an acoustic neuroma, although the natural course of acoustic neuromas has not been reviewed in detail. METHODS The clinicopathologic features and the postoperative growth of tumors were evaluated in 32 patients with acoustic neuromas. This study was undertaken to assess the variability of the growth potential of cells within an acoustic tumor and to determine the relationships between the growth rate and the clinicopathologic characteristics of the patients with acoustic neuromas, including age at surgery, gender, tumor location and preoperative size, the duration of the symptoms, the presence of cystic regions, the presence of Antoni type A and B cells, the tumor cell density, tumor vascularity, mitotic rate, the presence of hyaline degeneration and hemosiderin deposition, nucleolar organizer regions (NORs), and the level of proliferating cell nuclear antigen (PCNA). RESULTS The growth patterns of the tumors were divided into three groups according to their growth rate: a regression group, a "no-growth" group (growth rates from 0-0.11 cm/year) and a progression group (growth rates from 0.19-1.72 cm/year). An additional operation was required in all patients whose growth rate was more than 0.38 cm/year. A statistical study on the factors associated with an increased growth rate showed that the three histopathologic factors most significantly associated with a postoperative growth rate were hyaline degeneration (p < 0.05), cell density (p < 0.005), and PCNA labeling index (p < 0.005). CONCLUSIONS These results strongly suggest that acoustic tumors can be subdivided into several groups, based upon different biologic activities and tumor growth rates.

Adult↗

PubMed1991

Influence of histochemical preparation on acoustic parameters of liver tissue: a 5-MHz study.

In this study the influence of various histological techniques on the acoustic parameters of liver tissue was investigated. Radiofrequency (RF) echographic data were obtained in vitro from 21 liver samples taken from 8 white New Zealander rabbits. The samples were measured in four different subsequent histological tissue processing conditions (freshly excised, 4% buffered formalin fixed, after it went through a paraffin cycle and after staining with hematoxylin and eosin). The acoustic parameters that were obtained from the rf data were velocity of sound, slope of the attenuation coefficient versus frequency between 1.9 and 6.9 MHz, attenuation coefficient at 4.4 MHz, slope of the backscattering spectrum between 1.9 and 6.9 MHz, and intercept of the backscattering spectrum. It was found that fixation by formalin preserves the acoustic properties of the tissue to a reasonable extent. Embedding in paraffin and deparaffinizing induces large changes in the acoustic properties of the tissue. As an alternative, freezing prior to cutting, rather than the paraffin cycle, was investigated also in 10 liver samples obtained from 4 New Zealander rabbits. This method produced no significant changes of the acoustic parameters and should therefore be preferred in acoustic microscopy.

Acoustics↗

PubMed1994

Filling patterns in left ventricular hypertrophy: a combined acoustic quantification and Doppler study.

OBJECTIVES: The purpose of this study was to evaluate the potential of acoustic quantification compared with Doppler echocardiography for assessment of left ventricular diastolic dysfunction. BACKGROUND: Diastolic dysfunction usually accompanies left ventricular hypertrophy. Although Doppler echocardiography is widely used, it has known limitations in the diagnosis of diastolic abnormalities. The ventricular area-change waveform obtained with acoustic quantification technology may provide an alternative to assess diastolic dysfunction. METHODS: Potential acoustic quantification variables (peak rate of area change and mean slope of area change rate during rapid filling, amount of relative area change during rapid filling and atrial contraction) were obtained and compared with widely used Doppler indexes of ventricular filling (isovolumetric relaxation time, pressure half-time, peak early diastolic velocity/peak late diastolic velocity ratio, rapid filling, atrial contribution to filling) in 16 healthy volunteers and 30 patients with left ventricular hypertrophy. RESULTS: Criteria for abnormal relaxation were present in 68% of patients by acoustic quantification and in 64% of patients by Doppler echocardiography. However, abnormal relaxation was identified in 80% of patients by one or both methods. Acoustic quantification indicated abnormal relaxation in the presence of completely normalized Doppler patterns and in patients with mitral regurgitation or abnormal rhythm with unreliable Doppler patterns. CONCLUSIONS: Acoustic quantification potentially presents a new way to assess diastolic dysfunction. This technique may be regarded as complementary to Doppler echocardiography. The combined use of the methods may improve the diagnosis of left ventricular relaxation abnormalities.

Acoustics↗

PubMed2005

Acoustic reflectometry esophageal profiles minimally affected by massive gas ventilation.

Acoustic reflectometry can be used to distinguish between breathing tube placement in an esophagus vs the trachea via characteristic area-distance profiles for both cavities. In the cardiopulmonary resuscitation setting, capnography may be useless because the patient has little or no pulmonary circulation. With the breathing tube in the esophagus, can massive ventilation with a manual resuscitation bag, as might occur in the cardiopulmonary resuscitation setting, markedly alter the form of the obtained esophageal reflectometry profile? Nine hounds were induced, endotracheally intubated, mechanically ventilated, and anesthetized. Area-distance profiles were obtained with a 2-microphone acoustic reflectometer customized to measure areas up to 50 cm. Acoustic reflectometer profiles were obtained in intubated esophagi as follows: (1) baseline nonventilated state, (2) after aggressive 2-handed manual ventilation with high inspiratory pressures, rapid respiratory rates, and large tidal volumes for periods of 0.5, 1, and 1.5 minutes, upon detachment of the resuscitation bag, and (3) after esophagogastric decompression. We hypothesized that massive gas ventilation has no effect on the esophageal peak areas (null hypothesis), and used a paired t test for statistical significance (P < .05). For times of 0.5, 1.0, and 1.5 minutes, the ventilation volumes (mean +/- SD) were 25 +/- 7, 49 +/- 8, and 70 +/- 18 L. Massive gas ventilation caused minimal broadening and slight distal spread of the basal "hump". The mean peak area change was 0.18 +/- 0.35 cm2. For a paired t test (n = 9, df = 8), the corresponding t value was 1.54, with a P value of .16, which was incompatible with the null hypothesis. The experimental observations indicate a minimal effect of massive gas ventilation on the acoustic reflectometry esophageal profile. Hence, operator recognition of the altered canine acoustic reflectometer profile as that of an esophageal cavity is maintained, indicating that acoustic reflectometry may be useful in correctly identifying the site of breathing tube placement in out-of-hospital cardiac arrest situations despite massive esophageal ventilation.

Acoustics↗

PubMed2005

Long-term habituation of the startle response in mice evoked by acoustic and tactile stimuli.

The present study shows that repetitive presentation of tactile and acoustic stimuli evoke long-term habituation (LTH) of the startle response in C57BL/6J mice. This was indicated by a decrease in response strength over several days. For the LTH of the acoustic startle response two controls were included: first, developing hearing loss during the time of testing did not account for the startle decrease--only 7 days of acoustic stimulation but not 7 days of adaptation led to a decrease in the startle. Second, repetitive presentation of loud acoustic startle stimuli did not raise the auditory threshold, which might otherwise have accounted for the startle decrease: prepulse inhibition (used here as a hearing test) was identical after both 7 days of acoustic startle stimulation and 7 days without stimulation. This proves that LTH to tactile and acoustic stimuli is present and fully functional in mice.

Animals↗

PubMed2006

Perceptual dissimilarities among acoustic stimuli and ipsilateral electric stimuli.

Five users of cochlear implants who had residual acoustic hearing in the implanted ear postoperatively participated in a study comparing the percepts elicited by acoustic and electric stimuli. The stimuli comprised pulse trains delivered to single electrodes and pure tones presented ipsilaterally. In the experiments, 12 equally loud stimuli with differing frequencies, electrode positions, and pulse rates were generated. Subjects listened to all of the possible pairs of stimuli in each set, and provided a relative dissimilarity rating for the members of each stimulus pair. The data were analyzed using non-metric multi-dimensional scaling techniques. Stimulus spaces were plotted in two dimensions to represent the results for each subject with each stimulus set. The results suggested that one dimension was associated with a pitch-like percept, related to the acoustic tone frequency and the active electrode position. The second dimension separated the acoustic stimuli from the electric stimuli. Generally, the electric pulse rate seemed to have a relatively small perceptual effect in this experimental context. Overall, the results show that acoustic pure tones are perceived as very different from electric pulse trains delivered to single electrode positions with constant rate, even when both the acoustic and the electric stimuli are presented to the same ear.

Acoustic Stimulation↗

PubMed2005

Validation of soft bottom benthic habitats identified by single-beam acoustics.

Acoustic diversity charts were produced for a Portuguese soft bottom mid-shelf area, depth from 30 to 90 m, using a single-beam echo sounder coupled to the acoustic systems QTC VIEW Series IV and V. A similar acoustic pattern was identified by both systems, which, after ground-truth interpretation based in available sediment and biological data, established a preliminary spatial distribution model of the benthic habitats in this coastal area. However, some of the acoustic areas were interpreted using one or very few sediment and benthic samples. A specific validation survey was conducted a posteriori, in which the positioning of the sediment and benthic community sampling sites was based on the acoustic diversity previously identified. The results clearly confirm the benthic habitats distribution model suggested by the acoustic method, indicating a high potential for the use of such approach in the identification and mapping of large-scale soft bottom coastal shelf habitat diversity.

Acoustics↗

PubMed2001

Acoustic and electroacoustic spectroscopy for characterizing concentrated dispersions and emulsions.

We describe two different techniques (acoustics and electroacoustics), both of which employ ultrasound instead of light for extracting information about the properties of liquid-based dispersions. Ultrasound can propagate through samples that are not transparent for light, which open up many new applications not possible with classical light scattering methods. Acoustic and electroacoustic techniques offer a unique opportunity to characterize concentrated dispersion, emulsions and microemulsions in their natural states. Elimination of a dilution step required for most other techniques (light scattering, sedimentation, electrophoresis) is crucial for an adequate characterization of liquid dispersions, especially when the high concentration leads to structured systems. As with any macroscopic method, ultrasonic techniques characterize the sample in two steps. The first step is to measure some macroscopic property. The second step involves some theoretical treatment of the measured raw data which yields the desired information. Acoustic spectroscopy deals with measuring the attenuation of ultrasound within a certain frequency range. Electroacoustic spectroscopy has two implementations depending on the driving force. We emphasize here on the so-called Colloid Vibration Current (CVI) which is generated by the sound wave as it passes through the dispersion. A review of the theoretical basis of acoustics and electroacoustics is given, with emphasis on models that have been applied to concentrated systems. Recently, new theories have been developed for both acoustics and electroacoustics using a 'coupled phase model' and 'cell model concept'. The coupled phase model is widely used for describing a relative motion of the particles and liquid in the sound wave. The cell model approach opens the way to include both particle-particle interactions and polydispersity into the theoretical model. Experimental evidence is presented that shows that this new approach is successful in concentrated systems up to 45% vol. A short review of the possible applications of acoustics and electroacoustics measurements to a range of systems is presented including: ceramics, mixed dispersed systems, chemical-mechanical polishing abrasives, emulsions, microemulsions and latex materials.

Acoustics↗

PubMed2003

Nicotine and ethanol enhancements of acoustic startle reflex are mediated in part by dopamine in C57BL/6J mice.

Nicotine has been shown to have additive as well as antagonistic effects on behavior stimulated by ethanol. Here, we examine the effects of nicotine, ethanol, and the coadministration of each drug on acoustic startle responding in C57BL/6J mice. Mice were tested at a range of decibel levels (80-115 dB, 5 dB increments), with administration of 0.031, 0.062, 0.125, and 0.25 mg/kg nicotine or 0.5, 1.0, 1.5, and 2.0 g/kg ethanol. Nicotine and ethanol each caused an increase in the acoustic startle response at the highest and lowest doses tested, respectively. Mecamylamine, a nicotinic receptor antagonist, administered in combination with nicotine or ethanol attenuated these increases in acoustic startle responding. Nicotine and ethanol, administered together, did not produce greater enhancement of startle than when administered alone. Haloperidol (1 mg/kg) was administered in combination with nicotine or ethanol to investigate if dopamine modulated nicotine or ethanol enhancement of acoustic startle. It was found that the increase in acoustic startle responses observed with ethanol or nicotine was attenuated by haloperidol. Thus, ethanol or nicotine may enhance the acoustic startle reflex through a common dopaminergic mechanism.

Acoustic Stimulation↗

PubMed2004

The use of acoustic microscopy to study the mechanical properties of glass-ionomer cement.

OBJECTIVES: The aim of the study was to investigate the relationship between microstructure, acoustic and mechanical properties of hardened dental cement samples, prepared with different powder/water ratios. METHODS: Glass-ionomer dental cement samples, prepared with a standard amount of cement powder and different amounts of water have been examined after being hardened. Surface microstructure and ultrasound, longitudinal and shear velocities were obtained with a scanning acoustic microscope. Conditional effective elastic modulus and Poisson's ratio have been calculated using longitudinal and shear sound velocity values. Then on the same samples elastic modulus and microhardness have been determined by standard tests. Additional samples have been used to determine compressive strength. RESULTS: Density; conditionally instantaneous elastic modulus; high-elasticity modulus and compression strength of the samples decrease when large amounts of water were used for their preparation. At the same time porosity and microhardness of the cement matrix increase. Acoustic parameters and parameters of elasticity, calculated on the basis of sound velocity, demonstrated changes, similar to those obtained in standard mechanical tests. SIGNIFICANCE: The established relation between microstructure, acoustic and mechanical parameters demonstrated a high capacity of acoustic microscopy application for non-destructive characterization of dental materials. A particular advantage of the acoustic microscopy is the opportunity to evaluate microstructure and mechanical properties on the same sample.

Compressive Strength↗

PubMed1997

Evaluation of the nasal cavity by acoustic rhinometry in normal and allergic subjects.

With acoustic rhinometry, one can detect a difference in response to a topical decongestant between normal and allergic subjects at the minimal cross-sectional area. The minimal cross-sectional area corresponds in most cases to the anterior end of the inferior turbinate or the first valley, which occurs after the nose piece of the acoustic rhinometer on the acoustic rhinometry graph. Allergic patients typically have an increase in nasal mucosal swelling, which leads to a decrease in the nasal volume and area and, subsequently, to an increase in congestion. In this study acoustic rhinometry was used to test normal and allergic subjects before and after the application of a topical decongestant (1% phenylephrine (Neo-Synephrine)). Symptoms were measured by a five-point scale. Results showed that increasing symptom scores demonstrated a trend toward being related to decreasing area as measured at the minimal cross-sectional area or nasal valve. The average total percent change at the minimal cross-sectional area was calculated for both groups and compared. The normal subjects had an average total percent area change at the minimal cross-sectional area of 15.6% +/- 14.8%, and the allergic subjects had a percent change of 24.6% +/- 20.8%. This represents a significant difference between the normal and allergic subjects in response to the topical decongestant at the minimal cross-sectional area (p = 0.04). However, the average total percent change was not significantly different between the two groups at the second and third valleys. At the second valley, the normal subjects had a percent change of 40% +/- 17.5%, and the allergic subjects had a percent change of 36% +/- 18.5%. At the third valley, the normal subjects had a percent change of 35% +/- 15.4%, and the allergic subjects had a percent change of 32% +/- 20.6% (p = 0.4 and 0.5, respectively). The total area was calculated by adding measurements from both right and left nasal cavities for each subject in an attempt to control the effect of the nasal cycle. Acoustic rhinometry makes it possible to detect a trend in the relationship between either a decrease in area at the minimal cross-sectional area or a decrease in the total volume from 0 to 7 cm into the nasal cavity and congestion. A statistically significant difference between normal and allergic subjects in their response to a topical decongestant at the minimal cross-sectional area was detected by acoustic rhinometry at the nasal valve.

Acoustics↗

PubMed2000

Spontaneous involution of acoustic tumors.

OBJECTIVE: To determine spontaneous involution of unilateral acoustic tumors in untreated patients. STUDY DESIGN: Outcome of a continuous study, 1982 to present. SETTING: Private tertiary otology/neurotology referral center. PATIENTS: Patients with unilateral acoustic tumors for whom interval imaging was selected rather than surgery or gamma knife radiation, 1982 to the present. INTERVENTION: Interval imaging with computerized axial tomography and/or magnetic resonance imaging. MAIN OUTCOME MEASURE: Spontaneous involution of acoustic tumors. RESULTS: Forty-seven patients with unilateral acoustic tumors were untreated and followed up with interval imaging for 1 to 12.5 years. Six patients (13%), whose ages ranged from 59 to 74 years and who were followed up for 4.3 to 12.5 years, demonstrated imaging evidence of spontaneous acoustic tumor involution. Involution varied from 3.4 mm to 15 mm. CONCLUSIONS: Spontaneous involution of acoustic tumors does occur. Long-term follow-up is necessary to determine this potential.

Adult↗

PubMed2000

Audiometric findings in patients with acoustic neuroma.

OBJECTIVE: Hearing loss remains the most common symptom associated with acoustic neuroma. This study documents the audiometric findings from 721 acoustic neuroma procedures. STUDY DESIGN: This was a retrospective study. The preoperative audiometric data were compiled and were analyzed by patient age, gender, tumor size, time of surgery, and neurofibromatosis Type 2 (NF 2). Postoperative audiometric data were arranged and compiled in the same way. The hearing classification proposed by the AAO-HNS was applied to all preoperative and postoperative cases. SETTING: Tertiary referral center. PATIENTS: Surgically confirmed acoustic neuroma patients who had not previously received surgical or radiosurgical therapy. Patients underwent surgery by the retrosigmoid approach. INTERVENTION: Surgical removal of an acoustic neuroma. MAIN OUTCOME RESULT: Provision of pure tone and speech data from a group of acoustic neuroma patients, including application of the recently introduced and accepted AAO-HNS hearing classification system. RESULTS: Preoperative audiometric data were obtained from 694 of 721 patients (96%), of whom 619 had measurable hearing. Postoperative audiometry was performed on 606 patients; 152 had usable data. The combined preoperative audiometric data revealed a high frequency sensorineural hearing loss. Word recognition was servicable. The postoperative pure tones and word recognition scores were worse than preoperative scores. Age, gender, tumor size, and time of surgery had some impact on the preoperative hearing and the postoperative result; NF 2 did not. CONCLUSIONS: The study confirms that hearing alteration is almost universal in acoustic neuroma patients. Hearing preservation is possible in a significant number of cases; however, the postoperative auditory function tends to be worse.

Adolescent↗

PubMed2002

Acoustic cavitation in phacoemulsification: chemical effects, modes of action and cavitation index.

High-intensity ultrasound (US) energy (HIUE) has been extensively used in the last 3 decades in a wide range of surgical procedures, including phacoemulsification. The generation of radicals and sonoluminescence (SL) by application of continuous-wave (CW) HIUE to an aqueous medium under conditions simulating cataract phacoemulsification surgery is demonstrated by electron paramagnetic resonance (EPR) spectroscopy and a sensitive photon-detecting system. The findings provide direct evidence for the generation of acoustic cavitation in the simulated intraocular environment, pointing out that generation of acoustic cavitation in clinical phacoemulsification and other surgical applications of US is possible. The findings imply that the effects of acoustic cavitation in aqueous medium may contribute to the endothelial damage observed clinically following phacoemulsification cataract surgery. Saturation of the irrigating solution with various gases modifies the acoustic cavitation. Saturation of the irrigating solution with CO2 practically eliminates acoustic cavitation, with the concomitant elimination of radicals and SonL. CO2 may be utilized clinically to suppress acoustic cavitation in phacoemulsification and other medical applications. A cavitation index (CI) is introduced for the purpose of standardizing phacoemulsification instrumentation and other medical US devices that employ HIUE.

Acoustics↗

PubMed1997

Human offset auditory brainstem response: effects of stimulus acoustic ringing and rise-fall time.

Offset auditory brainstem response (ABR) traditionally has been thought to be an artifactual response elicited by stimulus acoustic ringing. Additionally, offset ABR's sensitivity to stimulus rise-fall time has been associated with concurrent changes in acoustic ringing. The present study tested the validity of offset ABR by recording the response in 40 young, normal-hearing adults using tone burst stimuli with varying degrees of acoustic ringing and various rise-fall times. Stimuli were computer-generated 10-ms tone bursts of 500 and 2000 Hz. In Experiment 1, offset ABR was recorded using stimuli with no acoustic ringing, normal ringing, and excessive ringing. Rise-fall time was held constant at 0.5 ms. In Experiment 2, rise-fall time was manipulated in a stimulus with no ringing. In Experiment 3, only rise time was manipulated in a no-ringing stimulus, while fall time was held constant at 0.5 ms. Reliable offset ABRs were recorded for all degrees of acoustic ringing, including the "no-ringing' condition. Offset ABR was sensitive to rise and fall times, and was elicited best with a 500-Hz stimulus. The results indicate that offset ABR is a real response and not an artifact produced by acoustic ringing.

Acoustic Stimulation↗

PubMed2001

Acoustic measures of symptoms in abductor spasmodic dysphonia.

Speech of patients with abductor spasmodic dysphonia (ABSD) was analyzed using acoustic analyses to determine: (1) which acoustic measures differed from controls and were independent factors representing patients' voice control difficulties, and (2) whether acoustic measures related to blinded perceptual counts of the symptom frequency in the same patients. Patients' voice onset time for voiceless consonants in speech were significantly longer than the controls (p = 0.015). A principle components analysis identified three factors that accounted for 95% of the variance: the first factor included sentence and word duration, frequency shifts, and aperiodic instances; the second was phonatory breaks; and the third was voice onset time. Significant relationships with perceptual counts of symptoms were found for the measures of acoustic disruptions in sentences and sentence duration. Finally, a multiple regression demonstrated that the acoustic measures related well with the perceptual counts (r2 = 0.84) with word duration most highly related and none of the other measures contributing once the effect of word duration was partialed out. The results indicate that some of the voice motor control deficits, namely aperiodicity, phonatory breaks, and frequency shifts, which occur in patients with ABSD, are similar to those previously found in adductor spasmodic dysphonia. Results also indicate that acoustic measures of intermittent disruptions in speech, voice onset time, and speech duration are closely related to the perception of symptom frequency in the disorder.

Adult↗