Incoherent optical fluctuation flowmetry for detecting limbs with hemodynamically significant stenoses in patients with type 2 diabetes.

INTRODUCTION: The development of new highly accurate, inexpensive and accessible methods for the detection of lower-extremity peripheral artery disease (LE-PAD) in diabetic patients is required. The aim of this study was to evaluate the accuracy of a new incoherent optical fluctuation flowmetry (IOFF) method in detecting legs with hemodynamically significant stenoses compared to ankle brachial index (ABI) and transcutaneous oximetry (TcPO2) in patients with diabetes mellitus (DM). MATERIALS AND METHODS: Patients were recruited into 2 groups. Group 1 included patients with DM without LE-PAD and/or diabetic foot syndrome; Group 2 included patients with DM and LE-PAD. All patients underwent the following measurements: ultrasound (reference method), ABI, TcPO2, and the new IOFF method. RESULTS: The new IOFF method showed a sensitivity of 79.5% and a specificity of 89.8% in detecting limbs with hemodynamically significant stenosis (AUC 0.890, CI 0.822-0.957). TcpO2 allows the diagnosis of LE-PAD with 69.2% sensitivity and 86.2% specificity (AUC 0.817, CI 0.723-0.911). Using a standard ABI cut-off of less than 0.9, the sensitivity and specificity for this parameter were 34.5% and 89.7%, respectively. Increasing the diagnostic cut-off of the ABI on the study group to 0.99 improved sensitivity to 84.6% and specificity to 78% (AUC,0.824 CI 0.732-0.915). CONCLUSIONS: The new IOFF technique has demonstrated high sensitivity and specificity in the detection of LE-PAD in patients with DM. The high accuracy, rapid measurement, and potential availability suggest that the new IOFF method has a high potential for clinical application in the detection of PAD.

Skin microvascular reactivity in patients with diabetic retinopathy.

AIMS: Early detection of microangiopathic complications of diabetes mellitus (DM) is necessary to analyze the patient's condition and prevent disease progression. The study was aimed to investigate the relationship between the presence of retinopathy and decreased reactivity of the microcirculatory bed in patients with diabetes. METHODS: The study involved 130 subjects: healthy volunteers (n = 48), DM patients without retinopathy (n = 53) and with retinopathy (n = 29). Skin microvascular reactivity was assessed on the forearm using laser Doppler flowmetry with a local heating test combined with occlusion. RESULTS: The slope of local thermal hyperemia curve (Slope-120) and other parameters of microvascular reactivity showed difference in pairwise comparisons between the groups. Slope-120 had the highest sensitivity (0.759) and specificity (0.717) in detection of diabetic retinopathy. The decrease of Slope-120 was associated with retinopathy (odds ratio (OR) - 8.3 (2.9-24.1), p < 0.001), even after adjusting for other factors (OR - 11.0 (1.6-77.2), p = 0.016). CONCLUSIONS: Thus, assessment of skin microvascular reactivity may be a useful test for detecting signs of microangiopathic complications and for screening patients in risk group. Decreased microvascular reactivity has been shown to be prospective as an independent indicator of retinopathy in type 1 DM.

Incoherent Optical Fluctuation Flowmetry: A New Method for the Assessment of Foot Perfusion in Patients with Diabetes-Related Lower-Extremity Complications.

(1) Background: To date, there are no studies evaluating the ability of the incoherent optical fluctuation flowmetry (IOFF) method to assess foot tissue perfusion. The aim of this study was to evaluate the correlation between perfusion values measured by IOFF and TcPO2 in patients with diabetes-related lower-extremity complications. (2) Methods: This was an observational, cross-sectional, two-center study. Diabetic patients with peripheral artery disease and/or diabetic foot ulcers were studied (n = 27, examinations were carried out on 54 legs). Perfusion in the foot tissues was assessed using TcPO2 (reference standard for this study) and the IOFF method. (3) Results: High correlation coefficients of all perfusion parameters measured by IOFF with TcPO2 (Rs 0.7 to 0.76) were shown. The study demonstrated that the IOFF method allows, with a sensitivity of 85.7% and a specificity of 90.0%, the identification of patients with a critical decrease in TcPO2 < 20 mmHg. (4) Conclusions: The high correlation of IOFF parameters with TcPO2 and the moderately high sensitivity and specificity in detecting patients with severe ischemia of foot tissues shows the promise of the method for assessing a tissue perfusion in patients with diabetes-related lower-extremity complications.

Methods of Non-Invasive In Vivo Optical Diagnostics in the Assessment of Structural Changes in the Skin Induced by Ultraviolet Exposure in an Experimental Model.

BACKGROUND: This paper demonstrates the use of optical diagnostic methods to assess the dynamic skin changes observed in acute and chronic exposure to ultraviolet (UV) radiation in vivo. METHODS: Firstly, in order to initiate photoaging (chronic UV exposure), animals (n = 40) were divided into two groups: chronic UV exposure (n = 30), and control (n = 10; without irradiation). Photoaging in animals was induced by chronic repeated exposure to UVA radiation three times per week, for 12 weeks continuously, while the UV dose increased stepwise over the course of the experiment (55 minimal erythema doses (MED) in total). Laser fluorescence spectroscopy (LFS), optical tissue oximetry (OTO), laser Doppler flowmetry (LDF), and optical coherence tomography (OCT) of the shaved dorsum skin were performed regularly, once per week until the conclusion of the study. At 0, 5, and 12 weeks of the experiment, histological examination of animal tissues using hematoxylin/eosin and Masson's trichrome staining was performed. At the second stage, erythema was induced in mice (n = 15) by acute UV exposure at high doses. The colorimetric assay of the image from a digital RGB camera was used to evaluate the erythema index. RESULTS: The tissue content index ηcollagen of collagen was appropriate for the characterization of skin photoaging. Significant differences (p < 0.05) in ηcollagen were found between the control and photoaging groups from the 5th to the 9th week of the experiment. In addition, the rate of collagen degradation in the control group was about half that of the photoaging group. This marker allows the differentiation of photo- and chronoaging. OCT revealed the main optical layers of the skin in compliance with the histological pattern. The analysis of the RGB camera images provided visualization of the acute skin reaction to UV radiation. CONCLUSIONS: This study demonstrates the applicability of optical methods for the quantitative assessment of acute and chronic skin effects of UV exposure in vivo.

Reduced microvascular reactivity in patients with diabetic neuropathy.

BACKGROUND: Neurogenic regulation is involved in the development of microcirculation response to local heating. We suggest that microvascular reactivity can be used to estimate the severity of diabetic polyneuropathy (DPN). OBJECTIVE: To evaluate the prospects for using the parameters of skin microvascular reactivity to determine the severity of DPN. METHODS: 26 patients with diabetes mellitus were included in the study (patients with retinopathy (n = 15), and without retinopathy (n = 11)). The severity of DPN was assessed using Michigan Neuropathy Screening Instrument (MNSI) and Norfolk QOL-DN (NQOLDN). Skin microcirculation was measured by laser Doppler flowmetry with local heating test. RESULTS: There were revealed moderate negative correlations between microvascular reactivity and the severity of DPN (for MNSI (Rs = -0.430), for NQOLDN (Rs = -0.396)). In patients with retinopathy, correlations were stronger than in the general group (for MNSI (Rs = -0.770) and NQOLDN (Rs = -0.636)). No such correlations were found in patients without retinopathy. CONCLUSION: Correlation of the microvascular reactivity and DPN was revealed in patients with registered structural disorders in microvessels (retinopathy). The lack of such correlation in patients without retinopathy may be explained by the intact compensatory mechanisms of microvessels without severe disorders.

Approaches to improve the predictive value of laser Doppler flowmetry in detection of microcirculation disorders in diabetes mellitus.

BACKGROUND: Laser Doppler flowmetry is widely used in scientific studies of blood microcirculation but constrained in clinical use due to the low diagnostic significance. OBJECTIVE: This research is aimed at creation of approaches to prognostic value increase in detection of microcirculation disorders in patients with type 2 diabetes mellitus. METHODS: The study included 10 volunteers and 10 patients with t2DM. Participants were observed using postural-heating test with LAKK-02 complex. We calculated median microcirculation for each period and then held a retroactive classification of the surveyed groups. RESULTS: Statistically significant differences between groups were found in the perfusion during the combination of postural and heating impacts. Conversion of this perfusion in the relative index (Irel) (relative to the baseline perfusion), allowed us to increase the significance of the differences. The value of AUC (95% CI) during the ROC-analysis in reverse classification was 0.81 (0,60-1,0) for the period of the impacts combination, and 0.93 (0,81-1,0) for Irel index. CONCLUSIONS: We demonstrated the possibility of using LDF method to achieve predictive value in the detection of microcirculatory disorders in an individual patient with diabetes. This extends the perspectives of the method beyond the purely scientific research.

Fluorescence of radiation-induced tissue damage.

PURPOSE: The aim of this study was evaluating changes in the photosensitizer fluorescence in vivo in the radiation-induced damage area in comparison of intact areas with a simultaneous assessment of changes both in blood parameters and in histological data. MATERIALS AND METHODS: The study was conducted in white outbred SHK mice (n = 21). Their right hindlimbs were irradiated with a dose of 25 Gy after the intraperitoneal injections of photosensitizer 'Photosens'. Fluorescence intensity was traced in vivo by a laser diagnostic system for seven weeks. Simultaneously, histological examination of the damaged areas and blood tests were performed. RESULTS: An increased intensity of the laser-induced fluorescence of the photosensitizer 'Photosens' in the damaged areas, compared to the intact symmetrical ones was observed. Laboratory blood tests and histological examination showed changes that may indicate the occurrence of inflammation. CONCLUSION: Enhanced intensity of the exogenous fluorescence of the photosensitizer in the radiation-induced inflammation of noncancerous tissues was observed. The obtained results may potentially affect an interpretation of the results of intraoperative tumors navigation that have been previously irradiated and can be used for selection of an individualized dose fractionation algorithm in radiology.

Fluorinated Polyurethanes, Synthesis and Properties.

Fluorinated polyurethanes with a glass transition temperature as low as -139 °C and a decomposition onset temperature of 247-330 °C were prepared by a reaction of fluorinated alcohols with aromatic and cycloaliphatic diisocyanates in solution or melt.