Electrical responses of the superior olivary complex in Vespertilionidae and Rhinolophidae to ultrasonic stimuli with different fill frequency

Global and single unit responses of the superior olivary complex were investigated during ultrasonic stimulation at different frequencies in two species of bats from the Vespertilionidae, which emit frequency-modulated signals and the Rhinolophidae, which utilize almost monochromatic (80 ± 1 kHz) echolocation cries. Maximal sensitivity to ultrasound in the Vespertilionidae was found at frequencies of 10–40 kHz, and in the Rhinolophidae also within the range 10–40 kHz but with a second increase in sensitivity in the region 82–86 kHz. Sharply tuned neurons were more numerous in the Rhinolophidae than in the Vespertilionidae. Neurons whose response in the echolocation frequency band changed in character depending on the fill frequency of the stimulus were found in Rhinolophidae: a phasic discharge occurs over a wide range of frequencies and a tonic discharge at the characteristic frequency; the latter was also observed over a limited range of intensities.A. A. Zhdanov Leningrad State University. Translated from Neirofiziologiya, Vol. 5, No. 1, pp. 33–39, January–February, 1973.     

Frequency-dependent ultrasound-induced transformation in E. coli

Ultrasound-enhanced gene transfer (UEGT) is continuing to gain interest across many disciplines; however, very few studies investigate UEGT efficiency across a range of frequencies. Using a variable frequency generator, UEGT was tested in E. coli at six ultrasonic frequencies. Results indicate frequency can significantly influence UEGT efficiency positively and negatively. A frequency of 61 kHz improved UEGT efficiency by ~70 % higher, but 99 kHz impeded UEGT to an extent worse than no ultrasound exposure. The other four frequencies (26, 133, 174, and 190 kHz) enhanced transformation compared to no ultrasound, but efficiencies did not vary. The influence of frequency on UEGT efficiency was observed across a range of operating frequencies. It is plausible that frequency-dependent dynamics of mechanical and chemical energies released during cavitational-bubble collapse (CBC) are responsible for observed UEGT efficiencies.     

Inhibition of barnacle cyprid settlement using low frequency and intensity ultrasound

Low frequency, low intensity ultrasound was demonstrated as an effective inhibitor of barnacle cyprid settlement. When the same substratum vibration amplitude (10.05 nm) and acoustic pressure (5 kPa) were applied, ultrasound at a frequency of 23?kHz significantly reduced cyprid settlement. The mechanism appeared to differ from the ultrasonic cavitation induced inhibition previously reported as no increased mortality was observed, and no change in the exploratory behaviour of cyprids was observed when they were exposed to this continuous ultrasonic irradiation regime. The application of ultrasound treatment in an intermittent mode of '5?min on and 20?min off' at 20-25?kHz and at the low intensity of 5?kPa produced the same effect as the continuous application of 23?kHz. This energy efficient approach to the use of low frequency, low intensity ultrasound may present a promising and efficient strategy regarding irradiation treatment for antifouling applications.     

Ultrasonic startle behavior in bushcrickets (Orthoptera; Tettigoniidae)

1. In the present work, we show that in flight, bushcrickets not previously known to respond to ultrasound alter their flight course in response to ultrasonic stimuli. Such stimuli elicit in flying Neoconocephalus ensiger an extension of the front and middle legs along the body and a rapid closure of all 4 wings (Fig. 1). This is a short latency acoustic startle response to ultrasound, consistent with acoustic startle responses of other insects. 2. The percentage of trials on which acoustic startle responses were elicited was maximum (90%) for sound frequencies ranging from 25 to at least 60 kHz. No acoustic startle response was observed at frequencies of 5 or 10 kHz (Fig. 2). The threshold for the response was roughly 76 dB between 25 to 60 kHz (Fig. 2) and the behavioral latency was 45 ms (Fig. 3). Recordings from flight muscles show that they cease discharging during the acoustic startle response (Fig. 4). 3. The characteristics of the acoustic startle response match those of an auditory interneuron called the T-neuron. The frequency sensitivity of this neuron is greatest for sound frequencies ranging from 13 to 60 kHz (Fig. 6). Moreover, we found that the neuron produces many more spikes to ultrasound (30 kHz) of increasing intensities than to a conspecific communication sound, whose dominant frequency is 14 kHz (Fig. 7).     

The high frequency properties of brain tissue

Computer modeling is becoming increasingly important in the realm of brain biomechanics and injury. New computer simulations range from modeling of brain surgery, a low frequency, high strain event, to predicting injury as a result of an impact to the head, a high frequency event with varying strain magnitudes. This range of modeling efforts requires characterization of the tissue over as wide a frequency and strain range as possible. Research done to date has concentrated on the low frequency properties of the tissue. Complex compression and complex shear moduli have been measured at frequencies up to 350 Hz. Impact modeling requires use of frequency data at significantly higher frequencies than these. The "wave-in-a-tube" ultrasonic method was applied to brain tissue to determine mechanical properties at frequencies between 100 kHz and 10 MHz. Of these properties, only complex bulk modulus |K*| is fairly invariant (2133 MPa) with respect to frequency. Complex shear and complex Young's moduli vary with frequency and approach an asymptotic upper limit. Some variation in complex Poisson's ratio was also observed.     

Phonotaxis in flying crickets

The steering responses of three species of field crickets, Teleogryllus oceanicus, T. commodus, and Gryllus bimaculatus, were characterized during tethered flight using single tone-pulses (rather than model calling song) presented at carrier frequencies from 3-100 kHz. This range of frequencies encompasses the natural songs of crickets (4-20 kHz, Fig. 1) as well as the echolocation cries of insectivorous bats (12-100 kHz). The single-pulse stimulus paradigm was necessary to assess the aversive nature of high carrier frequencies without introducing complications due to the attractive properties of repeated pulse stimuli such as model calling songs. Unlike the natural calling song, single tone-pulses were not attractive and did not elicit positive phonotactic steering even when presented at the calling song carrier frequency (Figs. 2, 3, and 9). In addition to temporal pattern, phonotactic steering was sensitive to carrier frequency as well as sound intensity. Three discrete flight steering behaviors positive phonotaxis, negative phonotaxis and evasion, were elicited by appropriate combinations of frequency, temporal pattern and sound intensity (Fig. 12). Positive phonotactic steering required a model calling song temporal pattern, was tuned to 5 kHz and was restricted to frequencies below 9 kHz. Negative phonotactic steering, similar to the 'early warning' bat-avoidance behavior of moths, was produced by low intensity (55 dB SPL) tone-pulses at frequencies between 12 and 100 kHz (Figs. 2, 3, and 9). In contrast to model calling song, single tone-pulses of high intensity 5-10 kHz elicited negative phonotactic steering; low intensity ultrasound (20-100 kHz) produced only negative phonotactic steering, regardless of pulse repetition pattern. 'Evasive', side-to-side steering, similar to the 'last-chance' bat-evasion behavior of moths was produced in response to high intensity (greater than 90 dB) ultrasound (20-100 kHz). Since the demonstration of negative phonotactic steering did not require the use of a calling song temporal pattern, avoidance of ultrasound cannot be the result of systematic errors in localizing an inherently attractive stimulus when presented at high carrier frequencies. Unlike attraction to model calling song, the ultrasound-mediated steering responses were of short latency (25-35 ms) and were produced in an open loop manner (Fig. 4), both properties of escape behaviors.(ABSTRACT TRUNCATED AT 400 WORDS)     

A comparative study of isolation-induced ultrasonic vocalization in rodent pups.

The purpose of this study was to determine whether species differences in neonatal vocalizations of rodent pups could be observed. Ultrasonic vocalizations of pups of 5 rodent species, mouse (ICR), vole (Microtus arvalis), Syrian hamster, rat (Wistar-Imamichi), and Mongolian gerbil were recorded from 3 to 15 or 21 days of age. Recordings were made under conditions of separation from mothers and litter mates in a cooled chamber (approximately 10 degrees C). The major species differences observed were age specific and species specific frequencies. The Mongolian gerbil displayed a different frequency change with age. Namely, the day on which ultrasonic vocalizations ceased was delayed in Mongolian gerbil compared with the other rodents. The modal peak frequencies of ultrasound emitted from pups at 3 days of age were low (around 35 kHz) in the vole and the Syrian hamster, medium (around 45 kHz) in the rat and the Mongolian gerbil, and high (around 55 kHz) in the mouse.     

Ultrasound-assisted extraction of some branded tea: Optimization based on polyphenol content,antioxidant potential and thermodynamic study

Tea is one of the top beverages used around the world every day, which contains a high amount of polyphenols and antioxidants. The main aim of this research is to quantify some marketed black tea (Rabea, Lipton, Alkbous, Green gold and Haritham) for phenolic contents and antioxidant potential evaluation by ultrasound solvent extraction and was compared with conventional extraction. Ultrasonic extraction was optimized by considering frequencies (26 kHz, 40 kHz), temperature (30, 40 and 50 °C), and power (30, 40 and 50%) at a fixed time of 30 min. In both the ultrasonic frequencies, 40 °C temperature and 40% power combination exhibited highest cumulative yield (mg/100 g DW), total phenolic content (mg gallic acid/g DW), flavonoids (mg/g DW) and DPPH radical scavenging activity (%) in all branded tea. Within each brand of tea, at any temperature-power combination at particular frequency results were not significantly different. But, at a similar condition of temperature power results were found significantly different between two frequencies. Furthermore, ultrasonic extraction process was analyzed thermodynamically by selecting some basic parameters. Thermodynamics results showed the extraction process was feasible, spontaneous and irreversible. Also, 26 kHz ultrasonic probe is more appropriate for the extraction purpose and thermodynamically more acceptable as compared to 40 kHz ultrasonic bath. Moreover, Haritham was selected as the best tea brand due to its high polyphenol contents and antioxidant potential.     

In-situ spectroscopic investigation of ultrasonic assisted unfolding and aggregation of insulin

It is well-known that fibrillogenesis of proteins can be influenced by diverse external parameters, such as temperature, pressure, agitation or chemical agents. The present preliminary study suggests that ultrasonic excitation at moderate intensities has a significant influence on the unfolding and aggregation behaviour of insulin. Irradiation with an average sound intensity of even as low as 70 mW/cm² leads to a lowering of the unfolding and aggregation temperature up to 7 K. The effect could be explained by an increase of the aggregation kinetics due to ultrasonically induced acoustic micro-streaming in the insulin solution that most probably enhances the aggregation rate. The clear and remarkable effect at relatively low sound intensities offers interesting options for further applications of ultrasound in biophysics and biochemistry. On the other hand, a process that causes a change of kinetics equivalent to 7 K also gives a warning signal concerning the safety of those medical ultrasonic devices that work in this intensity range.     

Environmental ultrasound in laboratories and animal houses: a possible cause for concern in the welfare and use of laboratory animals

Many laboratory animals are known to be sensitive to sounds (ultrasounds) beyond the nominal upper limit (20 kHz) of the human hearing range. Sources of sound in laboratories and animal houses were examined to determine the extent of ambient ultrasound. Of 39 sources monitored, 24 were found to emit ultrasonic sounds. Many of these (e.g. cage washers and hoses) also produced sound in the audible range. Running taps, squeaky chairs and rotating glass stoppers created particularly high sound pressure levels and contained frequencies to over 100 kHz. The oscilloscopes and visual display units investigated provided particular cause for concern as they emitted sounds that were entirely ultrasonic and therefore were apparently silent. Ambient ultrasound therefore appears to be common in laboratories and animal houses. It is suggested that its effect on laboratory animals should be investigated and guidelines on acceptable levels be formulated.     

Therapeutic potential of electromagnetic fields for tissue engineering and wound healing

Ability of electromagnetic fields (EMF) to stimulate cell proliferation and differentiation has attracted the attention of many laboratories specialized in regenerative medicine over the past number of decades. Recent studies have shed light on bio‐effects induced by the EMF and how they might be harnessed to help control tissue regeneration and wound healing. Number of recent reports suggests that EMF has a positive impact at different stages of healing. Processes impacted by EMF include, but are not limited to, cell migration and proliferation, expression of growth factors, nitric oxide signalling, cytokine modulation, and more. These effects have been detected even during application of low frequencies (range: 30–300 kHz) and extremely low frequencies (range: 3–30 Hz). In this regard, special emphasis of this review is the applications of extremely low‐frequency EMFs due to their bio‐safety and therapeutic efficacy. The article also discusses combinatorial effect of EMF and mesenchymal stem cells for treatment of neurodegenerative diseases and bone tissue engineering. In addition, we discuss future perspectives of application of EMF for tissue engineering and use of metal nanoparticles activated by EMF for drug delivery and wound dressing.     

Ultrasonic singing by the blue-throated hummingbird: a comparison between production and perception

Blue-throated hummingbirds produce elaborate songs extending into the ultrasonic frequency range, up to 30 kHz. Ultrasonic song elements include harmonics and extensions of audible notes, non-harmonic components of audible syllables, and sounds produced at frequencies above 20 kHz without corresponding hearing range sound. To determine whether ultrasonic song elements function in intraspecific communication, we tested the hearing range of male and female blue-throated hummingbirds. We measured auditory thresholds for tone pips ranging from 1 kHz to 50 kHz using auditory brainstem responses. Neither male nor female blue-throated hummingbirds appear to be able to hear above 7 kHz. No auditory brainstem responses could be detected between 8 and 50 kHz at 90 dB. This high-frequency cutoff is well within the range reported for other species of birds. These results suggest that high-frequency song elements are not used in intraspecific communication. We propose that the restricted hummingbird hearing range may exemplify a phylogenetic constraint.     

Characterization of Dynamic Behaviour of MCF7 and MCF10A Cells in Ultrasonic Field Using Modal and Harmonic Analyses

Treatment options specifically targeting tumour cells are urgently needed in order to reduce the side effects accompanied by chemo- or radiotherapy. Differences in subcellular structure between tumour and normal cells determine their specific elasticity. These structural differences can be utilised by low-frequency ultrasound in order to specifically induce cytotoxicity of tumour cells. For further evaluation, we combined in silico FEM (finite element method) analyses and in vitro assays to bolster the significance of low-frequency ultrasound for tumour treatment. FEM simulations were able to calculate the first resonance frequency of MCF7 breast tumour cells at 21 kHz in contrast to 34 kHz for the MCF10A normal breast cells, which was due to the higher elasticity and larger size of MCF7 cells. For experimental validation of the in silico-determined resonance frequencies, equipment for ultrasonic irradiation with distinct frequencies was constructed. Differences for both cell lines in their response to low-frequent ultrasonic treatment were corroborated in 2D and in 3D cell culture assays. Treatment with ~ 24.5 kHz induced the death of MCF7 cells and MDA-MB-231 metastases cells possessing a similar elasticity; frequencies of > 29 kHz resulted in cytotoxicity of MCF10A. Fractionated treatments by ultrasonic irradiation of suspension myeloid HL60 cells resulted in a significant decrease of viable cells, mostly significant after threefold irradiation in intervals of 3 h. Most importantly in regard to a clinical application, combined ultrasonic treatment and chemotherapy with paclitaxel showed a significantly increased killing of MCF7 cells compared to both monotherapies. In summary, we were able to determine for the first time for different tumour cell lines a specific frequency of low-intensity ultrasound for induction of cell ablation. The cytotoxic effect of ultrasonic irradiation could be increased by either fractionated treatment or in combination with chemotherapy. Thus, our results will open new perspectives in tumour treatment.     

Inactivation of glucose-6-phosphate dehydrogenase in solution by low- and high-frequency ultrasound

Kinetics of inactivation of glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) in 0.1 M phosphate buffer (pH 7.4) within temperature range from 36 to 50 degrees C was studied comparatively under conditions of exposure of enzyme solution to low-frequency (LF, 27 kHz, 60 W/cm2) or high-frequency (HF, 880 kHz, 1.0 W/cm2) ultrasound (USD). Inactivation of G6PDH was characterized by effective first-order rate constants: (k(in)) total (summarized) inactivation; (k(in)*) thermal inactivation; and (k(in)(usd)) ultrasonic inactivation. Dilution of enzyme solution from 20 to 3 nM was accompanied by a significant increase in the values of the three rate constants. The following inequality was valid in all cases: k(in) > k(in)*. The rate constants increased upon increasing the temperature. The Arrhenius plots of the temperature dependencies of k(in) and k(in) (usd) have a salient point at 44 degrees C. The activation energy (Eact) of the total inactivation of G6PDH was higher than Eact for the process of ultrasonic inactivation of this enzyme. The two values were found to depend on USD frequency: Eact in case of inactivation with low-frequency ultrasound (LF-USD) was higher than in case of inactivation with high-frequency ultrasound (HF-USD). The rate of the ultrasonic induced inactivation of this enzyme substantially decreased in the presence of low concentrations of traps of radicals HO. (dimethylformamide, ethanol, and mannitol). This fact supports the conclusion that free radicals are involved in the mechanism of the G6PDH inactivation in solutions exposed to LF-USD and HF-USD. Ethanol was an effective protector of G6PDH inactivation in enzyme solutions exposed to USD.     

Effects of frequency and power of ultrasound on the size reduction of liposome

The solutions of liposome made of l-α-dilauroyl phosphatidylcholine are sonicated at various powers and frequencies (43-480 kHz), and the resultant change in the size of liposome is measured by the dynamic light scattering method. The ultrasonic power dissipated into the solution is determined by the calorimetric method in order to compare the effects of ultrasound of different frequencies. The faster reduction of the mean size of liposome is achieved at the lower frequency. Comparing at the same frequency and total energy, short-time irradiation of strong ultrasound is more efficient than long-time irradiation of weak ultrasound. These results indicate that the small number of cavitation events with stronger physical disturbance on liposome can reduce the size of the liposome more efficiently than the large number of cavitation events with weaker disturbance.     

Responses of the less sensitive acoustic sense cells in the tympanic organs of some noctuid and geometrid moths

The separate impulses contributed by the A1 and A2 acoustic sense cells in the tympanic organs of the noctuids, Autographa pseudogamma and Noctua c.-nigrum, and by the A1, A2, and A3 sense cells in the tympanic organ of the geometrid, Ennomos magnarius, were identified and counted from oscillograms grams made as the moths were exposed to ultrasonic pulses of different intensities. These data were used to construct curves relating the response/intensity characteristics of the less sensitive acoustic sense cells to that of the most sensitive unit, A1. The A2 sense cells of the noctuids were found to be from 20 to 30 dB less sensitive than A1 at sound frequencies to which these ears are most sensitive. In the geometrid it was found that the A2 sense cell was 15 dB less sensitive than A1 and 12 dB more sensitive than A3. Only traces of the response of the fourth geometrid acoustic sense cell (A4) could be identified at high sound intensities. In both noctuids and geometrids the acoustic sensitivity of A2 relative to A1 remained unchanged when tested at selected ultrasonic frequencies between 28 and 50 kHz. This confirms the conclusion that the ears of these moths are incapable of pitch discrimination over this frequency range. Each of the systems had a dynamic range of 40 to 45 dB, that of the geometrid showing greater range overlap of the four A cells and hence greater capacity for sound intensity discrimination.     

Characteristics of auditory brainstem responses in ground squirrels

Summary Auditory brainstem responses (ABRs) were characterized at 37 °C in ground squirrels (Citellus lateralis) which were implanted with recording screws to record ABRs, and a thermistor to record brain temperature. After two weeks ground squirrels were reanesthetized and tone pips and clicks were delivered through a TDH-49 headphone.Recorded ABRs were found to vary in a predictable manner as a function of stimulus frequency and intensity. At intensities above 50 dB SPL, ABRs could be recorded over the range tested (2–32 kHz). An 8 kHz tone pip was the best frequency for recording ABRs at the lowest stimulus intensities. Latencies decreased as stimulus frequencies increased from 4 kHz to 32 kHz.     

Therapeutic applications of ultrasound

Therapeutic applications of ultrasound predate its use in imaging. A range of biological effects can be induced by ultrasound, depending on the exposure levels used. At low levels, beneficial, reversible cellular effects may be produced, whereas at high intensities instantaneous cell death is sought. Therapy ultrasound can therefore be broadly divided into “low power” and “high power” applications. The “low power” group includes physiotherapy, fracture repair, sonophoresis, sonoporation and gene therapy, whereas the most common use of “high power” ultrasound in medicine is probably now high intensity focused ultrasound. Therapeutic effect through the intensity spectrum is obtained by both thermal and non-thermal interaction mechanisms. At low intensities, acoustic streaming is likely to be significant, but at higher levels, heating and acoustic cavitation will predominate. While useful therapeutic effects are now being demonstrated clinically, the mechanisms by which they occur are often not well understood.     

Progrès et perspectives ultrasonores

Ultrasonic waves are more and more widely used in medicine for the examination of organs by Doppler echography. The most frequently used ultrasonic frequencies range between 2 and 20 MHz. The relatively low cost and the non-invasiveness of ultrasound explain its increasing use in patients for both diagnosis and follow-up. In the near future, strong perspectives exist for the use of ultrasound for the treatment of tumours and also for local drug delivery. Several French research teams linked to university hospitals or research institutions have conducted key works for the progress of knowledge together with the development of new clinical methods. Several business units or industrial activities have been created after these works. Some landmarks will be found in this text on the features that today make the success of ultrasonic imaging and related modes, with the emphasis of the great and constantly renewed potential of creativity linked to those waves in the human body.