Noninvasive control of rhodamine-loaded capsules distribution in vivo

Using fluorescence spectroscopy system with fibre-optical probe, we investigated the dynamics of propagation and circulation in the microcirculatory system of experimental nanocapsules fluorescent-labelled (rhodamine TRITC) nanocapsules. The studies were carried out in clinically healthy Wistar rats. The model animals were divided into control group and group received injections of the nanocapsules. The fluorescent measurements conducted transcutaneously on the thigh surface. The administration of the preparation with the rhodamine concentration of 5 mg/kg of animal weight resulted in twofold increase of fluorescence intensity by reference to the baseline level. As a result of the study, it was concluded that fluorescence spectroscopy can be used for transdermal measurements of the rhodamine-loaded capsules in vivo

The development of attenuation compensation models of fluorescence spectroscopy signals

This study examines the effect of blood absorption on the endogenous fluorescence signal intensity of biological tissues. Experimental studies were conducted to identify these effects. To register the fluorescence intensity, the fluorescence spectroscopy method was employed. The intensity of the blood flow was measured by laser Doppler flowmetry. We proposed one possible implementation of the Monte Carlo method for the theoretical analysis of the effect of blood on the fluorescence signals. The simulation is constructed as a four-layer skin optical model based on the known optical parameters of the skin with different levels of blood supply. With the help of the simulation, we demonstrate how the level of blood supply can affect the appearance of the fluorescence spectra. In addition, to describe the properties of biological tissue, which may affect the fluorescence spectra, we turned to the method of diffuse reflectance spectroscopy (DRS). Using the spectral data provided by the DRS, the tissue attenuation effect can be extracted and used to correct the fluorescence spectra

Studies of age-related changes in blood perfusion coherence using wearable blood perfusion sensor system

Laser Doppler flowmetry (LDF) was used for detection of age-related changes in the blood microcirculation. The LDF signal was simultaneously recorded from the 3rd fingers' pads of both hands. Amplitudes of the blood flow oscillations and wavelet coherence of the signals were used for the data analysis. A statistical difference in the synchronisation of myogenic oscillations was found between the two studied age groups. Myogenic oscillations of blood perfusion in the younger group had a higher wavelet coherence parameter than in the older group. Observed site-specific and age-related differences in blood perfusion can be used in the future in the design of experimental studies of the blood microcirculation system in patients with different pathologies

Wearable sensor system for multipoint measurements of blood perfusion: pilot studies in patients with diabetes mellitus

The growing interest in the development of new wearable electronic devices for mobile healthcare provides great opportunities for the development of methods for assessing blood perfusion in this direction. Laser Doppler flowmetry (LDF) is one of the promising methods. A fine analysis of capillary blood ow structure and rhythm in the time and frequency domains, coupled with a new possibility of round-the-clock monitoring can provide valuable diagnostic information about the state of microvascular blood ow. In this study, wearable implementation of laser Doppler flowmetry was utilised for microcirculatory function assessment in patients with diabetes and healthy controls of two distinct age groups. Four wearable laser Doppler flowmetry monitors were used for the analysis of blood microcirculation. Thirty-seven healthy volunteers and 18 patients with type 2 diabetes mellitus participated in the study. The results of the studies have shown that the average perfusion differs between healthy volunteers of distinct age groups and between healthy volunteers of the younger age group and patients with diabetes mellitus. It was noted that the average level of perfusion measured on the wrist in the two groups of healthy volunteers has no statistically significant differences found in similar measurements on the fingertips. The wearable implementation of LDF can become a truly new diagnostic interface to monitor cardiovascular parameters, which could be of interest for diagnostics of conditions associated with microvascular disorders

Laser Doppler flowmetry in blood and lymph monitoring, technical aspects and analysis

The aim of this work was to study the possibilities of the laser Doppler flowmetry method for the joint study of microhaemo- and lymph circulation of human skin. Conducting a series of experimental studies allowed to trace the relationship of recorded signals of microcirculation of blood flow and lymph flow, as well as to study their oscillation nature by using wavelet analysis

Magnetic and structural properties of barium hexaferrite BaFe12O19 from various growth techniques

Barium hexaferrite powder samples with grains in the m-range were obtained from solid-state sintering, and crystals with sizes up to 5 mm grown from PbO, Na2CO3, and BaB2O4 fluxes, respectively. Carbonate and borate fluxes provide the largest and structurally best crystals at significantly lower growth temperatures of 1533 K compared to flux-free synthesis (1623 K). The maximum synthesis temperature can be further reduced by the application of PbO-containing fluxes (down to 1223 K upon use of 80 at % PbO), however, Pb-substituted crystals Ba1-xPbxFe12O19 with Pb contents in the range of 0.23(2) x 0.80(2) form, depending on growth temperature and flux PbO content. The degree of Pb-substitution has only a minor influence on unit cell and magnetic parameters, although the values for Curie temperature, saturation magnetization, as well as the coercivity of these samples are significantly reduced in comparison with those from samples obtained from the other fluxes. Due to the lowest level of impurities, the samples from carbonate flux show superior quality compared to materials obtained using other methods

Multimodal optical measurement for study of lower limb tissue viability in patients with diabetes mellitus

According to the International Diabetes Federation, the challenge of early stage diagnosis and treatment effectiveness monitoring in diabetes is currently one of the highest priorities in modern healthcare. The potential of combined measurements of skin fluorescence and blood perfusion by the laser Doppler flowmetry method in diagnostics of low limb diabetes complications was evaluated. Using Monte Carlo probabilistic modeling, the diagnostic volume and depth of the diagnosis were evaluated. The experimental study involved 76 patients with type 2 diabetes mellitus. These patients were divided into two groups depending on the degree of complications. The control group consisted of 48 healthy volunteers. The local thermal stimulation was selected as a stimulus on the blood microcirculation system. The experimental studies have shown that diabetic patients have elevated values of normalized fluorescence amplitudes, as well as a lower perfusion response to local heating. In the group of people with diabetes with trophic ulcers, these parameters also significantly differ from the control and diabetes only groups. Thus, the intensity of skin fluorescence and level of tissue blood perfusion can act as markers for various degrees of complications from the beginning of diabetes to the formation of trophic ulcers

The blood perfusion and NADH/FAD content combined analysis in patients with diabetes foot

Skin blood microcirculation and the metabolism activity of tissue were examined on the patients with type 2 diabetes. Laser Doppler flowmetry (LDF) with 1064 nm laser light source and fluorescence spectroscopy (FS) with excitation light of 365 nm and 450 nm have been used to monitor the blood perfusion and the content of coenzymes NADH and FAD. Concluding, the proposed combined LDF and tissue FS approach allows to identify the significant violations in the blood microcirculation and metabolic activity for type 2 diabetes patients

Investigation of speckle pattern dynamics by laser speckle contrast imaging

Abstract Laser speckle contrast imaging (LSCI) is a simple and quite powerful method for visualization of flow, microcirculation and perfusion. In current study the speckle contrast variations towards breaking ergodicity conditions are considered with a final aim of envision a practical approach allowing real-time imaging of variations in dynamic properties of complex fluids with an opportunity of quantitative interpretation of the obtained flowing map. As example of systems with static to dynamic transition, melting of Intralipid samples were studied. Also, investigation of influence of static layer thickness above the dynamic sample on the ergodicity condition has been studied

Flux Single Crystal Growth of BaFe12−xTixO19 with Titanium Gradient

Titanium substituted barium hexaferrite BaFe12−xTixO19 single crystal was grown by the top seeded solution growth method from flux on the seed with controlled cooling below 1175 °C. Titanium substitution level gradient in the single crystal in the vertical and horizontal directions was studied. Two planes were cut and polished. A justification for the linear gradient of Ti substitution in a BaFe12−xTixO19 single crystal is proposed; substitution levels in the center and periphery were determined. It was shown that upon growth by the top seeded solution growth method, crystals with a linear Ti substitution level gradient from x = 0.73 to x = 0.77 for a distance of 11 mm along pulling direction were obtained. The study led to the conclusion about the relationship of the gradient and changes in the composition of the nutrient solution