Ultrasound Doppler monitoring of soft tissues in vitro and tissue phantoms heating and thermal destruction induced by acoustic remote palpation.

The rise of shear strain value under temperature increase in biological tissue samples in vitro and tissue phantoms was studied and the range of shear modulus and viscosity calculated. It has been shown that the acoustic radiation force-based methods with the usage of ultrasound Doppler probing provides the potential ability of noninvasive real-time monitoring of tissues' ultrasound thermal destruction process. At that, the thermal destruction is possible under action of wave beam that creates the radiation force and local tissue displacements so that tissue ablation and acoustic remote palpation could be realized by means of the same ultrasound transducer. The experiments were performed using gelatin-based tissue-mimicking phantoms and freshly excised samples of bovine muscle tissue. It was determined also that fluctuating pattern of detected displacement amplitude variation is the indicator of the phase transitions beginning in the heated field of soft tissue or tissue phantom.

[The influence of gamma-irradiation and alimentry factors on prooxidant-antioxidant rat's liver and blood system].

The shift of prooxidant-antioxidant balance in side of prooxidants was revealed in rat liver mitochondria and in microsomes and in blood plasma in response to single irradiation (dose 8 Gy). The shift was more expressed in animals with nutrition unbalanced on animal proteins and antioxidant vitamins. In the main it was explained by the initially reduced activity of enzymatic antioxidant system and especially Se-dependent glutathione peroxidase activity. The apply of food addition from Aronia melanocarpa fruits had delayed lipid peroxidation activation in irradiated animals but practically had no effect on activity of enzymatic antioxidant system. The established essential decrease of Se-dependent glutathione peroxidase activity under unbalanced diet is considered the most crucial point in the maintenance of enzymatic antioxidant system reliability in irradiated animals.

[Activity of glutathione-dependent antioxidant system of the rat liver and blood depending on gamma-irradiation and diet].

The role of the glutathione-dependent antioxidant system in the prooxidant-antioxidant balance support was studied in the experiments with Wistar male rat under single gamma-irradiation (8 Gr dose), fed with unbalanced (as to animal proteins and antioxidant vitamins) diet and with addition of Aronia melanocarpa. Single gamma-irradiation of animals led to the decrease of selenium-dependent glutathione-peroxidase activity in the blood plasma and glutathione-S-transferase activity decrease in rat liver mitochondria. Animals which received the unbalanced food allowance under irradiation showed more expressed change of glutathione-dependent antioxidant enzymes activity, namely--proved decrease of glutathione-peroxidase and glutathione-S-transferase activity in liver microsomes and less expressed activation of selenium-dependent glutathione-peroxidase activity in the postmitochondrial fraction of laboratory animals liver. Introduction of the A. melanocarpa food supplement in the unbalanced diet of the laboratory animals which in vitro demonstrated expressed antioxidant and antiradical activity had no effect upon glutathione-peroxidase activity in the investigated tissues. Obtained data concerning significant decrease of the activity of glutathione-dependent antioxidant system and, particularly, of the selenium-dependent glutathione-peroxidase activity under the unbalanced diet condition may be useful in maintenance of prooxidant-antioxidant balance in the tissues of irradiated animals. Allowing for the above stated it is advisable to seek for new food additives which increase activity of the endogenous glutathione-dependent antioxidant enzymes for human tolerance improvement, especially under the unbalanced food allowance condition.

The estimation of elasticity and viscosity of soft tissues in vitro using the data of remote acoustic palpation.

The presented study revealed the significant dependence of displacement magnitude and strain relaxation on phantom elasticity and viscosity. It has been shown that simultaneous analysis of temporal behavior and magnitude of shear strain induced by the radiation force of focused ultrasonic beam gives the necessary data for quantitative estimation of tissue shear modulus because of the known functional dependencies of displacement on local viscosity and elasticity. As a result, the simplest calibration procedure of acoustic radiation force-based methods is performed and algorithm for separate reconstruction of tissue elasticity and viscosity is proposed. These findings were tested, in particular, using the data obtained for specially prepared phantoms containing calf liver and muscle tissue in vitro. The observed complex character of shear strain relaxation and noise in some tissue phantoms and tissues in vitro reduces the preciseness of viscoelastic properties estimation.

The influence of viscosity on the shear strain remotely induced by focused ultrasound in viscoelastic media.

Shear wave elasticity imaging (SWEI), an emerging acoustic technology for medical diagnostics, is based on remote generation of shear waves in tissue by radiation force in the focal region of an ultrasonic beam. In this study, the feasibility of Doppler ultrasonic technique to visualize the remotely induced shear waves was demonstrated. The generation of shear displacement in the focal region of a pulsed 1-MHz ultrasound beam with pulse duration of approximately about 2 ms and intensity levels on the order of 145 W/cm2, and consequent propagation of shear wave in tissue-mimicking and muscle tissue in vitro, were measured. The analysis of temporal behavior of shear displacement within the focal plane allowed estimation of shear wave velocities. The velocities were 4 and 7 m/s in hard phantom and tissue containing phantom, respectively. The measured shear displacements on the order of micrometers in gel-based phantoms are in reasonable agreement with theoretical estimates derived from an earlier developed model of shear wave generation by radiation force of focused ultrasound. The study revealed significant dependence of shear strain on the medium viscosity. The complex oscillatory character of shear strain relaxation in viscoelastic phantom and muscle tissue in vitro was observed.

Doppler ultrasound detection of shear waves remotely induced in tissue phantoms and tissue in vitro.

In shear wave elasticity imaging (SWEI), mechanical excitation within the tissue is remotely generated using radiation force of focused ultrasound. The induced shear strain is subsequently detected to estimate visco-elastic properties of tissue and thus aid diagnostics. In this paper, the mechanical response of tissue to radiation force was detected using a modified ultrasound Doppler technique. The experiments were performed on tissue mimicking and tissue containing phantoms using a commercial diagnostic scanner. This scanner was modified to control both the pushing and probing beams. The pushing beam was fired repetitively along a single direction while interlaced probing beams swept the surrounding region of interest to detect the induced motion. The detectability of inhomogeneous inclusions using ultrasonic Doppler SWEI method has been demonstrated in this study. The displacement fields measured in elastic phantoms clearly reveal the oscillatory nature of the mechanical relaxation processes in response to impulsive load due to the boundary effects. This relaxation dynamics was also present in cooked muscle tissue, but was not detected in more viscous and less elastic phantom and raw muscles. Presence of a local heterogeneity in the vicinity of the focal region of the pushing beam results in generation of a standing wave field pattern which is manifested in the oscillatory response of the excited region of the tissue. There has been made an assumption that dynamic characteristics of the relaxation process may be used for visualization of inhomogeneities.

[Effect of triton x-100 and glutaraldehyde on Ca2+- and Mg2+-ATPase activity of erythrocytes during irradiation]. / Vliianie tritona X-100 i glutarovogo al'degida na aktivnost' Ca2+- i Mg2+-ATP-az éritrotsitov pri obluchenii.

The effect of triton X-100 and glutaraldehyde on the changes in Ca(2+)- and Mg(2+)-ATPase activity of erythrocyte plasma membrane under irradiation of rat erythrocytes has been studied. It was found that irradiation of erythrocyte ghosts in a dose of 1000 Gy leads to the inhibition of the both enzymes. Triton X-100 enhanced the radiation effect, while glutaraldehyde decreased Ca(2+)-ATPase sensitivity to the action of radiation. The mechanisms of the effects observed are discussed.

[Effect of membranotropic agents on the activity of microsomal oxidoreductases]. / Vliianie membranotropnykh agentov na aktivnost' oksidoreduktaz mikrosom.

The effect of triton X-100 and glutaraldehyde on the functioning of microsomal oxidoreductases has been investigated. Triton X-100 was found to increase the enzymes activity. The decrease of oxidoreductases activity was observed in the presence of glutaraldehyde.

[Effect of ionizing radiation on the activity of microsomal oxidoreductases]. / Vliianie ioniziruiushchei radiatsii na aktivnost' mikrosomal'nykh oksidoreduktaz.

The effect of electrons with energy 5 MeV on the functional state of rabbit liver microsome oxidoreductases has been investigated. Decrease in enzyme activity upon irradiation with a dose of 10 kGy was found. The possible mechanisms of the effects observed are discussed.

[Effect of radiation on erythrocyte membrane structure using fluorescent probes]. / Issledovanie vliianiia radiatsii na strukturu membran éritrotsitov metodom fluorestsentnykh zondov.

The effect of electrons with the energy of 5 MeV on the erythrocyte membrane structure was investigated using a fluorescent probe (4-dimethylaminostiryl)-1-methylpyridinium (DSM). Analysis of a competitive binding of DSM and ribonuclease with the erythrocyte ghosts has shown that irradiation causes an increase in the constant of protein association with membranes. It is suggested that a negative surface change increase with irradiation.

[Effect of radiation on the electrophoretic mobility of erythrocytes]. / Vliianie radiatsii na élektroforeticheskuiu podvizhnost' éritrotsitov.

Electrons with energy 5 MeV have been studied for their effect on the electrokinetic properties of erythrocytes. The electrophoretic mobility of the cells was shown to decrease under the effect of radiation. It is supposed that the effect observed is determined by the structural changes of the membrane proteins.

[Effect of radiation on the structural state of erythrocyte membranes]. / Vliianie radiatsii na strukturnoe sostoianie membran éritrotsitov.

Using fluorescent probe 4-(n-dimethyl-aminostyryl)-1-methyl-pyridine (DSM) the effect of electrons with the energy 5 MeV on the structure of erythrocyte membrane has been investigated. It was found that in the irradiated erythrocyte ghosts the number of DSM binding sites increases. Irradiation was suggested to increase the negative surface charge of the erythrocyte membrane.

[Effect of ionizing radiation on the structure of erythrocyte membranes]. / Vliianie ioniziruiushchego izlucheniia na struktury membran éritrotsitov.

Effect of electrons with the energy 5MeV on the erythrocyte ghosts structure has been investigated using fluorescent probes 1.8-ANS and DSP-12. The number of ANS binding sites was shown to decrease as affected by irradiation. It was found that radiation caused reduction of the erythrocyte membrane surface area.

[Stimulation of gramicidin incorporation into lipid bilayer membranes by ultrasound]. / Stimuliatsiia vnedreniia gramitsidina v bisloinuiu lipidnuiu membranu ul'trazvukom.

Ultrasound effect on gramicidin incorporation into a bilayer lipid membrane has been investigated. The observed increase in the channel opening frequency points to the incorporation rate growth due to the thickness diminishing of near-membrane non-stirred layers. The dependence of ultrasound intensity on the layer thickness is presented.

[Effect of ultrasound on the ATPase activity of brain microsomes]. / Vliianie ul'trazvuka na ATFaznuiu aktivnost' mikrosom mozga.

Ultrasonic effects (0.88 MHz, 0.8 Wt X cm-2) on Na+, K+-ATPase and Mg2+-ATPase changed the values KM, Vmax, delta H not equal to, delta S not equal to and the activation energy, which can point to some changes in the structure of lipoprotein enzyme complexes.