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At least 631 records · Page 35Linked to original sources

PubMed1994

The value of ultrasonic cleaners in dental practice.

Ultrasonic cleaners are a valued aid to instrument cleaning in many general dental practices. This article reviews the different ways their cleaning efficiency has been assessed. It is recommended that burs and files should be cleaned ultrasonically before first use. Prophylaxis cups are not sufficiently decontaminated by ultrasonic cleaning and therefore should be discarded after use. Although instruments are visibly clean after ultrasonic cleaning and generally clean when viewed with an electron microscope, ultrasound alone is insufficient for sterilisation. Further avenues of research have been highlighted.

Decontamination↗

PubMed1999

A simple in vitro method for the evaluation of an ultrasonic nebulizer for drug delivery to intubated, ventilated patients and the effect of nebulizer and ventilator settings on the uptake of fluid from the nebulizer chamber.

Little is known about the performance of ultrasonic nebulizers during different ventilation patterns when these nebulizers are used to deliver drugs to intubated, ventilated patients. A method that enables the performance of an ultrasonic nebulizer to be evaluated is described. We used an in vitro model to examine the performance of the DeVilbiss Ultra-Neb 2000 ultrasonic nebulizer under positive pressure ventilation. Performance was measured at different rates of nebulization and under changing conditions of positive end-expiratory pressure (PEEP), inspiratory flow rate, inspiratory time and minute volume. The volume of saline nebulized was unchanged by variations in positive end expiratory pressure from 0 to 5 cm to 10 cm H2O, in minute ventilation and in inspiratory flow rate. An increase in the inspiratory time resulted in an increase in the volume of saline nebulized and this volume was greater as the power setting of the nebulizer was increased. We conclude that ultrasonic nebulizers may be affected by different patterns of ventilation and that this simple in vitro assessment of nebulizer function in an intensive care setting may be of value prior to nebulizer use.

Aerosols↗

PubMed1998

Inactivation of Bacillus subtilis spores by combining ultrasonic waves under pressure and mild heat treatment.

The inactivation of Bacillus subtilis spores by ultrasonic treatments under static pressure (Mano-Sonication, MS) and a combined MS/heat treatment (Mano-Thermo-Sonication) was investigated. The sporicidal effect of MS treatments depended on static pressure, amplitude of ultrasonic waves and treatment temperature. At 70 degrees C, pressure increments up to 500 kPa caused progressively more inactivation. An MS treatment at 500 kPa and 117 microns of amplitude for 12 min inactivated approximately 99% of the B. subtilis spore population. Over 500 kPa, further increments in pressure did not increase the percentage of inactivation. In the range 90-150 microns, an exponential relationship was observed between the amplitude of ultrasonic waves under pressure and the number of survivors. While an MS treatment (20 kHz, 300 kPa, 70 degrees C, 12 min) at 90 microns inactivated 75% of the B. subtilis spore population, the same treatment at 150 microns inactivated 99.9% of this population. The MS treatments at temperatures higher than 70 degrees C (MTS) led to more spore inactivation. In the range 70-90 degrees C, the combination of heat with an MS treatment (20 kHz, 300 kPa, 117 microns, 6 min) had a synergistic effect on spore inactivation. The inactivating effect of ultrasound was due neither to titanium particles eroded from the sonication tip, nor to free radicals released during ultrasonic treatment. The MS treatments sensitized spores of B. subtilis to lysozyme.

Atmospheric Pressure↗

PubMed2000

Endoscopic third ventriculostomy with ultrasonic contact microprobe.

The authors describe their first clinical experiences in endoscopic third ventriculostomy (ETV) with the original ultrasonic contact microprobe (UCM) designed at the Department of Neurosurgery in Zagreb. The analysis includes the clinical course of disease in eight patients submitted to surgery from May to September 1999 (3 men and 5 women, from 14 to 61 years of age). Surgery was performed in patients with neurological symptoms of elevated intracranial pressure and neuroradiological evidence of non-communicating hydrocephalus caused by mesencephalic aqueduct stenosis. The perforation in the base of the third brain ventricle made by the ultrasonic contact microprobe was widened by a balloon catheter. The authors have come to conclusion that the ETV when performed by contact ultrasonic microprobe is a small risk procedure in case of non-communicating hydrocephalus. For its small diameter (1.6 mm) and simple handling the newly designed contact ultrasonic microprobe is very suitable for use in neuroendoscopy as it enables fenestration of the third brain ventricle with minimal thermal and ultrastructural damage to the adjacent neurovascular structures. Further research will be focused on defining indications for the use of the device in other neuroendoscopic procedures as well.

Adolescent↗

PubMedDate not supplied

[Ultrasonic diagnosis in orthopedics].

Ultrasonics in medicine and especially ultrasonics in orthopedics are an essential enrichment of our ways of making a diagnosis. The development of modern diagnosis instruments in addition to the systematic research of the skeletal system and soft tissues have made it possible that this method can now also be employed in the special field of orthopedics. That doesn't mean that other imaging methods should be given up but rather that this new way of imaging should be seen as a completion and a screening method for the other procedures. Because of the easiness of applying ultrasonics there is also the danger of overestimating the extent to which this method can be used and the danger of misinterpreting findings because of a lack of knowledge. Both risks should be kept in mind when using ultrasonics so that this harmless method doesn't became dangerous to the patients after all.

Arthritis, Rheumatoid↗

PubMed2004

Separation of metal ions in nitrate solution by ultrasonic atomization.

In the ultrasonic atomization of metal nitrate solutions, the molar ratio of metal ions is changed between solution and mist. Small molar metal ions tend to be transferred to mist by ultrasonic wave acceleration, while large molar ions tend to remain in solution. As a result, metal ions can be separated by ultrasonic atomization. We show experimental data and propose a conceptual mechanism for the ultrasonic separation of metal ions.

Bismuth↗

PubMed2001

Study of the technological parameters of ultrasonic nebulization.

The principle of an ultrasonic nebulizer is based on the vibrations of a piezoelectric crystal driven by an alternating electrical field. These periodic vibrations are characterized by their frequency, their amplitude, and their intensity, which corresponds to the energy transmitted per surface unit. When the vibration in tensity is sufficient, cavitation occurs, and droplets are generated. Ventilation enables airflow to cross the nebulizer and to expel the aerosol droplets. For a given nebulizer, the vibration frequency of the piezoelectric crystal is fixed, often in the range 1-2.5MHz. In most cases, an adjustment in vibration intensity is possible by modifying vibration amplitude. The ventilation level is adjustable. The vibrations may be transmitted through a coupling liquid--commonly water--to a nebulizer cup containing the solution to be aerosolized. In this work, we studied the influence of the technological parameters of ultrasonic nebulization on nebulization quality. Our study was carried out with a 9% sodium chloride solution and a 2% protein solution (alpha1 protease inhibitor). Three different ultrasonic nebulizers were used. An increase in vibration frequency decreased the size of droplets emitted. The coupling liquid absorbed the energy produced by the ultrasonic vibrations and canceled out any heating of the solution, which is particularly interesting for thermosensitive drugs. An increase in vibration intensity did not modify the size of droplets emitted, but decreased nebulization time and raised the quantity of protein nebulized, thus improving performance. On the other hand, an increase in ventilation increased the size of emitted droplets and decreased nebulization time and the quantity of protein nebulized because more drug was lost on the walls of the nebulizer. High intensity associated with low ventilation favors drug delivery deep into the lungs.

Algorithms↗

PubMed2004

Cyanobacterial bloom control by ultrasonic irradiation at 20 kHz and 1.7 MHz.

Ultrasonic irradiations at high frequency of 1.7 MHz and low frequency of 20 kHz were tested to prevent cyanobacteria Spirulina platensis from bloom. The inhibition effectiveness at 1.7 MHz was much greater than that at 20 kHz. The cyanobacteria biomass was reduced by 63% after 5 min ultrasonic irradiation at 1.7 MHz, whereas three days were needed for the tested cyanobacteria to recover its original density. However, longer exposure time did not significantly enhance the inhibition. It was observed after ultrasonic irradiation that the gas vesicles in cells collapsed, which may result in cyanobacterial precipitation and photosynthetic inhibition. The concentration of chlorophyll a (Chla) was reduced and its biosynthesis was delayed in a 4-day continuous culture. The fluorescence spectra at 77K of phycobilisome (PBS) and absorption spectra of intact cells in vivo showed that light energy transfer in PBS was inhibited and phycocyanin (PC) was damaged much more acutely compared with Chla. These results indicated that 5 min ultrasonic irradiation at 1.7 MHz every third day might be an effective and economic operation mode for practical application.

Bacterial Proteins↗

PubMed1989

Evolution equations and ultrasonic wave propagation in biological tissues.

Fundamental research in ultrasonic diagnostics is often limited by the relatively simple models of propagation invoked in what is largely an empirical science. Careful discussion of the problem reveals the need for more sophisticated propagation theories as the basis of measurement techniques and for the interpretation of experimental results. It is thus important for dialogue between theoreticians and experimentalists in the field. The complexity of ultrasonic wave propagation in tissue arises from a combination of factors. First, there is the biochemical sophistication of the media concerned. Second, there is the variety of physical phenomena involved: the diffractive nature of the ultrasonic field, the presence of absorption, the presence of large scale inhomogeneities and small scale scatterers, and the possibility of finite amplitude propagation effects. It has tended to be the custom to deal with each of these problems on an individual basis with a second feature being introduced as a perturbation of the results obtained for the first. The present authors have been concerned to find a unified approach which will permit each of the effects to be taken into account in relation to the others. This approach is based on the application of two-dimensional evolution equations modelling ultrasonic propagation in non-cavitating soft tissues. The model incorporates all the propagation phenomena known from experimental studies, indicating a need for knowledge of nine material parameters for a complete description. It thus provides a basis for numerical investigation of the relative significance of the parameters under different conditions. This will permit identification of those that should be known experimentally with high precision and those that have a minor role in the propagation phenomena.

Biophysical Phenomena↗

PubMed2004

Clinical evaluation of a continuous minimally invasive glucose flux sensor placed over ultrasonically permeated skin.

Frequent monitoring and tight metabolic control of blood glucose levels can reduce microvascular complications and subsequent co-morbidities in patients with diabetes. Self-monitoring with finger sticks provides intermittent data at best, and results in poor compliance. We report on a minimally invasive system that continually measures glucose flux through ultrasonically permeated skin. Ten patients with diabetes were enrolled in a clinical study to determine correlation between data collected by glucose biosensors placed over ultrasonically treated skin sites (two per patient), and blood glucose readings were taken every 20 min over an 8-h period. Glucose flux biosensors measured amperometric current proportional to hydrogen peroxide level, generated from catalytic conversion of glucose by glucose oxidase; the sensor was coupled to the skin by a thin hydrogel containing an osmotic extraction buffer, creating a gradient for glucose transport through the skin. The biosensors were attached to small portable meters that recorded time, current, and temperature readings every 5 s. At the conclusion of the study period, meter recordings were downloaded for data processing. Skin sites were examined for irritation due to biosensor contact. Data from glucose biosensors with completed data sets had a correlation coefficient of 0.84, and 95% of the data pairs (n = 241) were in the A + B region of a Clarke error grid. Ultrasonic pretreatment lasting about 10 s resulted in improved conductance in all patients. No patients complained of pain or irritation at any time during the study. Continuous monitoring of glucose flux through ultrasonically permeable skin is safe and feasible.

Adult↗

PubMed1989

Ultrasonic degradation of DNA.

Different results are obtained when DNA in aqueous solution and DNA in biological tissue are exposed to ultrasound. At intensities of ultrasound comparable to those applied clinically, ultrasonication is able to degrade purified DNA in aqueous solution, making ultrasonication a useful tool for preparing DNA fragments in vitro. Ultrasonic degradation of DNA in solution occurs by breaking hydrogen bonds and by single-strand and double-strand ruptures of the DNA helix. Two mechanisms are mainly responsible: cavitation and a thermal or mechanical effect. Stable cavitation is seen at low intensities of ultrasound. Increasing the intensity of the ultrasound above 2 W/cm2 is followed by increases in single-strand ruptures due to the creation of free radicals by transient cavitation. Following sonication, the distribution of the resulting DNA fragments approaches a lower size limit of 100-500 bp. Breaks in the DNA helix occur mainly between oxygen and carbon atoms, resulting in DNA fragments with a phosphorylated 5' end and a free alcohol at the 3' end. The relative lack of specificity in degrading the DNA helix makes ultrasonication a complementary alternative to the highly specific fragmentation obtained by restriction endonucleases.

DNA↗

PubMed1994

Newly developed ultrasonic aspirator and its application for endoscopic surgery.

The authors have developed an ultrasonic aspirator to assist in urologic endoscopic surgery. It appeared that ultrasonic aspiration of bladder tumors was clinically efficient in transurethral surgery. Tumors 1 to 2 cm in diameter could be aspirated completely with this instrument alone. The application of the ultrasonic aspirator, which has also been designed with a coagulating function, to laparoscopic lymphadenectomy was evaluated. A special probe sheath was used to insulate it when using coagulation current. During operation, perivascular fatty tissue was removed safely with the aspirator. In the near future, the ultrasonic aspirator will be one of the most effective tools in laparoscopic surgery.

Aged↗

PubMed2000

Jet and ultrasonic nebulization of single chain urokinase plasminogen activator (scu-PA).

Recent studies have indicated that the deposition of intra-alveolar fibrin may play a central role in the pathogenesis of acute respiratory distress syndrome (ARDS). Our aim was to study whether the indigenous fibrinolytic agent (urokinase) normally present in the alveoli can be administered locally by nebulization in a recombinant zymogen form as single chain urokinase plasminogen activator (scu-PA). We aimed to characterize the particle size distribution, drug output, and enzymatic activity of scu-PA after nebulization with a Ventstream jet nebulizer (Medic-Aid, Bognor Regis, UK) and a Syst'AM DP-100 ultrasonic nebulizer (Pulmolink, Kent, UK). The particle size distribution was measured with a laser diffraction method and the drug output was determined by collection on filters. The amount of protein on the filters was determined with the Lowry method, and the enzymatic activity after nebulization was measured with a microtiter fibrin plate assay. The mass median diameter (MMD) of the scu-PA aerosol generated with the ultrasonic nebulizer was 3.69 (3.53-3.83) microm and with the jet nebulizer 2.96 (2.91-3.03) microm (p < 0.001). The drug output from the two nebulizers did not differ between nebulizers (p = 0.054). Fibrinolytically active scu-PA was generated with both nebulizers, but in contrast to jet nebulization, ultrasonic nebulization caused partial inactivation of scu-PA (p < 0.001). In conclusion, nebulization of scu-PA with the jet nebulizer is superior to ultrasonic nebulization in terms of particle size distribution and preservation of fibrinolytic activity.

Aerosols↗

PubMed1975

Ultrasonic study of normal and fractured bone.

Ultrasonic velocity measurement in bone can be used as a clinical tool that will accurately and objectively monitor the progress of fracture healing. This technique may provide a rational basis for evaluating the effectiveness of various modalities in clinical treatment. The eventual goal of this technique is to determine the status of healing fractures, prescribe appropriate treatment, give the rationale for the timing and form of a rehabilitative program that would accelerate the patient's return to productivity. An instrument has been developed to measure ultrasonic velocity in the long bones of the extremities. Serial measurements of tibial fractures and the measurement of a large group of normals shows no statistically significant differences in ultrasonic measurements have been found on the basis of race, sex, or pregnancy among normals. But a numerically small but statistically significant variation with age was found. While the number of fracture cases observed was small, the evidence is clear that ultrasonic measurement in fractured tibia may give a more reliable indication of the general pattern of healing response than the clinical and roentgenographic examination.

Adult↗

PubMed2002

Detecting bacterial colonization of implanted orthopaedic devices by ultrasonication.

Glycocalyx-producing bacteria have been observed on orthopaedic devices that were removed for reasons other than infection. It has been suggested that the bacteria adhere to foreign surfaces within a biofilm and elude standard culture techniques. The authors adapted previously used ultrasonication protocols that disrupt the surface biofilm before culturing removed orthopaedic devices from patients without clinical evidence of infection. Patients having revision total joint arthroplasty of the hip or knee who lacked current or prior clinical evidence of infection were studied prospectively. During surgery, the femoral component and a corresponding control femoral implant were placed in separate sterile bags of saline. The implant and saline combination was placed in an ultrasonication bath for 30 minutes at 60 Hz. The saline solution was passed through a 0.45-microm pore filter, and the filter residue was cultured on sheep blood agar. None of the 21 implants yielded positive culture on routine microbiologic testing. However, using the ultrasonication protocol, a coagulase-negative Staphylococcus grew from one of the removed implants. Numerous total joint implant failures that are attributed to aseptic loosening may be a result of subclinical infection from bacteria within a biofilm. The current study supports the concept that biofilm-protected bacterial colonization of implants may occur without overt signs of infection and ultrasonication can be used to enhance identification of these bacteria.

Adult↗

PubMedDate not supplied

Ultrasonic diagnostic system for interactive interrogation of adult brain through intact skull.

An integrated ultrasonic system has been developed employing static gray scale imaging, digital image processing, and analyses of quantitative ultrasonic backscatter for interactive interrogation of brain through the adult human skull. Operating at 750 kHz, to avoid severe spatial and temporal pulse distortion which accompany ultrasonic transkull transmission at higher frequencies, storage and image processing of successive images taken at selected gain settings in the same image plane allow the reconstruction of a composite cross-section of the brain and skull and enable visualization of internal brain structure. Analyses of digitized backscatter data obtained with the visualization transducer over selectable interrogation paths referenced to the cross-sectional image permit quantitative classification of tissue type independent of qualitative visual image analysis, such that enhanced diagnostic potential is provided. A previous paper described in detail the modifications of the commercial ultrasound diagnostic unit which serves as the core of this system. The present paper presents the rationale for the integrated system design approach, as well as a description of graphics display and tissue classification features which have been incorporated into the instrumentation configuration and are deemed necessary for successful transkull ultrasonic imaging and diagnosis.

Brain Diseases↗

PubMed2003

Bacteriological evaluation of passive ultrasonic activation.

The purpose of this study was to evaluate the influence of passive ultrasonic activation on root canal disinfection. Sixty human teeth (group A: upper incisors, group B: upper canines, and group C: distobuccal root of first upper molars) were selected and sterilized in an autoclave. A standardized inoculum was placed into the canals, and they were incubated for 72 h at 37 degrees C. Then, they were divided into subgroup 1, which received sterile saline (SS) as an irrigant, and subgroup 2, which received sterile saline with passive ultrasonic activation (SU). The endodontic treatment was performed with a crown-down technique. Bacteriological identification of surviving colonies was carried out. Surviving colonies were higher when ultrasonics was not used (group A: SS: x 32.13, SU: x 13.53; group B: SS: x 53.70, SU: x 44.60; group C: SS: x 39.16, SU: x 29.40). The homogeneity proportion tests to compare the results of both subgroups showed that the surviving proportions were higher (p = 0.01) when the ultrasonic activation was not used.

Colony Count, Microbial↗

PubMed2003

A comparison of the cleaning efficacy of short-term sonic and ultrasonic passive irrigation after hand instrumentation in molar root canals.

A total of 100 maxillary molar canals were hand instrumented to a master apical file size #35 and flared to a size #60 file. The canals were randomly divided into 5 groups of 20 each. Group 1 received no further treatment. Groups 2 and 3 received passive sonic irrigation for 30 and 60 s, respectively. Groups 4 and 5 received passive ultrasonic irrigation for 30 and 60 s, respectively. The roots were split longitudinally and photographed with a digital camera. The apical portion of the root was magnified to 100x. A debris score was calculated for the apical 3 and 6 mm. The debris score was calculated as a percentage of the total area of the canal that contained debris as determined by pixels in Adobe Photoshop 5.0. Passive sonic or ultrasonic irrigation, for as little as 30 s, resulted in significantly cleaner canals than hand filing alone. Ultrasonic passive irrigation produced significantly cleaner canals than passive sonic irrigation, when sonic and ultrasonic passive irrigation were compared with only each other.

Analysis of Variance↗