Investigation of a correlation between taxane-based chemotherapy and the ultrasonic time-of-flight of human fingernails.

BACKGROUND: Medical practitioners have long associated the physical appearance of human fingernails with certain underlying health conditions due to their direct connection to the vascular system. The objective of this study was to demonstrate how human fingernails can potentially be used as a biomarker to determine the severity of a patient's reaction to chemotherapy. METHODS: Quantitative investigation of fingernails in patients undergoing taxane-based chemotherapy was conducted using a high-frequency 50 MHz ultrasound device in B-mode in the form of a pilot study. Time-of-Flight (TOF) ultrasonic signal measurements were recorded longitudinally across fingernails over three time intervals; (before treatment, in the middle of treatment, and on the last day of treatment); a neuropathy assessment and photographs were also taken for comparison. RESULTS: A total of 17 patients were examined in this study with ages ranging from 35-69 years old with both weekly and biweekly chemotherapy regimens. Onycholysis and fingernail discoloration were observed in 8 of the 17 patients. White transverse lines and white lunula were observed on 4 of the 17 patients. Quantitative assessment revealed a TOF median decrease in fingernails during the first half of chemotherapy treatment; conversely, TOF median was found to have increased during the second half. Median TOF measurements at the end of treatment were found to return to approximately that of the baseline value. CONCLUSION: This was a novel application of ultrasound in fingernails as chemotherapy biomarkers and further studies should be considered to verify and expand on the results obtained in this study.

[Non-destructive ultrasonic technique of enamel thickness measurement].

An ultrasonic technique of enamel thickness measurement has been proposed. In this technique, a thin tray with a hole is placed on the surface of the tooth and the tip of the ultrasonic probe is inserted in this hole to prevent lateral shift of the tip during adjustment of angular position of the probe. Results of the ultrasonic measurements carried out on the extracted teeth with the enamel layer thickness in a range of 1-0.3 mm and the inclination angle up to 0.1 show that the relative thickness measurement error does not exceed ± 2-3%. Typical deviation between the ultrasonic data and the results of the destructive evaluation of the specimens is about ± 0.05 mm.

[Acoustic microscopy application for the evaluation of restorative materials bonding quality. Experimental investigation].

Ultrasound transmission and reflection at the interface between restorative material and tooth tissue have been investigated using experimental flat-parallel models and whole extracted human teeth with restorations. It has been found that in the case of good bonding the ultrasound wave energy practically does not reflect at the cement/dentin interface and propagates into dentin layer. If any microscopic cavity had been formed between cement and dentin, the most part of the acoustic energy would be reflected from the interface between cement and gaseous or liquid contents of that cavity. The results acquired have been used for the interpretation of morphological peculiarities of the adhesive bonding area in visual images, non-destructively obtained in acoustic microscope ultrasound frequency - 50 MHz. The differences discovered could be used as a base for the design and development of new ultrasound methods for the restorative materials bonding evaluation as well as for secondary caries revealing.

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.

[Acoustic microscopy methods in studies of the filling materials microstructure]. / Ispol'zovanie metodov akusticheskoi mikroskopii dlia issledovaniia mikrostruktury plombirovochnykh materialov.

The structure of filling materials (kemfil, polyacrylate cement, and Dentis, material produced by Stomadent Firm in Russia) at the interface with human dentin was studied in teeth subjected to retrograde filling with preliminary appendectomy. A prototype of table wide-field short pulse scanning acoustic microscope (50 mHz) (Acoustic Microscopy Center, Institute of Biochemical Physics of Russian Academy of Sciences) and Elsam acoustic microscope (200 mHz) (Leitz, Germany) were used. The results indicate that analysis of acoustic characteristics, including the data of acoustic microscopy, helps investigate the cement microstructure and evaluate the compactness and elasticity of samples; moreover, structural elements of the material, which are undetectable by other methods, are seen on acoustic images. These data can be used for evaluating the relationship between the microstructure and formation of mechanical properties, and, maybe, the patterns of cement interactions with dental tissues.

Green's function analysis of electromagnetic waves in two-layered periodic structures with fluctuations in thickness.

A general method for the construction of the Green's function for finite one-dimensional inhomogeneous layers is developed. Using the results of this method the exact analytical Green's function for periodic dielectric structures is found. As an example of its application, the influence of fluctuations of the widths of the basic layers on the reflection and transmission of electromagnetic waves propagating through the structure is investigated. The results are applied to the design of optical switching systems with periodic dielectric structures as the operating medium. The same Green's function can be used to solve a wide variety of other problems.

Switching of electromagnetic waves by two-layered periodic dielectric structures.

The propagation of electromagnetic waves in two-layered periodic dielectric structures is investigated. The systematic dependence of the reflection coefficient on the parameters characterizing the structure is studied in detail. Using results of this exact analysis we investigate the influence of variation of the structure parameters on the reflection and transmission coefficients. As an example, we consider the changes in the structure parameters under an elastic stress. We show that under practically realizable conditions the reflection and transmission of the electromagnetic wave can be changed by as much as 80-90 % by creating a constant elastic stress inside the structure.

A new focusing ultrasonic transducer and two foci acoustic lens for acoustic microscopy.

The textured piezoelectric film of a new organic-based material produced by vapor deposition was used as an active element of a focusing ultrasonic transducer. The transducer exhibits near theoretical lateral and axial resolution, unipolar pulse response to a step voltage, and 30 dB insertion losses in an octave frequency band. The transducer is acoustically transparent over a wide frequency range and can be fabricated on a concave spherical surface of the standard acoustic lens. The resulting double transducer and two foci acoustic lens are capable of improving the quality of the surface structure imaging or of being used in continuous wave reflection acoustic microscopy.

Temperature effects in the focal region of acoustic microscope.

New analytical expressions that account for radial and axial heat flow in a medium and immersion liquid are derived for the case of a Gaussian-shaped ultrasonic beam pattern near a focus of an acoustic microscope in thin or semi-infinite absorbing materials for two cases corresponding to the studying of biological or solid-state samples. In the first case, it is assumed that the sample together with the immersion represents a medium uniform in its thermal properties. In the second case, it is supposed that heat conductivity of a sample material is much more than that of the immersion liquid. Solutions are given for temperature growth along the axis of symmetry of acoustic lenses. The use of these equations in estimation of the temperature growth gives a maximum value of one degree for biological samples with the absorption coefficient ten times more than that of water and 10(-3) degrees C for samples of silicon for the microscope with a maximum ultrasonic intensity of 10(3) W/cm(2) at 500 MHz and with water as an immersion liquid.

[Effect of ultrasound on the membrane potential and embryonic development of sea urchin eggs]. / Vliianie ul'trazvuka na membrannyi potentsial i émbrional'noe razvitie iaitsekletok morskogo ezha.

Eggs of sea urchin Strongylocentrotus intermedius were exposed to continuous wave ultrasonic energy at a frequency of 2 MHz for 3 min. Ultrasonic treatment results in the appearance of monstrous embryos that die at the latest stages of their development. The number of dead embryos sharply grows with the increase in the spatial average intensity from 0.4 W/cm2 up to 1.6 W/cm2, when it comprises 100%. Dramatic decrease from 99% to 17% in the absolute value of transmembrane potential for both fertilized and unfertilized eggs was observed after ultrasonic treatment. These results seem to be caused by the action of stable cavitation. The given estimations show that for ultrasonic intensities more than 0.2 W/cm2 and providing the presence of gaseous bubbles in the vicinity of eggs shell the value of shear stress in an egg shell becomes great enough to cause the cytoplasmic gel fragmentation.

[Self-oscillations of biological microbodies]. / Sobstvennye kolebaniia biologicheskikh mikroob''ektov.

Theoretical analysis of natural oscillation spectra of different kind of cells is presented. The study of received dispersive equation shows that the character of the cell natural movement depends on its size and the viscosity of internal and external liquids. If the depth of viscous wave penetration is small in comparison with the cell radius, the natural movements are weak damping oscillations. If the depth viscous wave penetration is comparable to the cell size, we have a relaxation process of cell form restoration.

[The effect of ultrasound on the antigenic activity of human erythrocytes]. / Issledovanie deistviia ul'trazvuka na antigennuiu aktivnost' éritrotsitov cheloveka.

The effect of ultrasound (frequency 0.88 MHz, intensity from 0.05 to 1 W/cm2) on alterations in antigenic activity has been investigated in vitro using ABO antigens of human erythrocytes. The existence of threshold doses of ultrasound influence has been found. These doses are shown to be independent of ultrasound intensity. The dependence of the effect on erythrocyte concentration has been established. Individual and group differences in the antigenic resistance to ultrasonic exposure in donors of groups A and B have been revealed. A drop in antigenic activity equal to 97% has been obtained.