Laser Doppler Flowmetry Technique Research Articles

Comparative analysis of LDF phase portraits in periodontal microcirculation among patient with type 2 diabetes mellitus

Relevance. Periodontal diseases are among the most prevalent conditions affecting the oral cavity, often leading to tooth loss. Comorbid conditions, especially type 2 diabetes mellitus (DM2), can significantly influence the health of periodontal tissues by altering microcirculatory dynamics.Materials and methods. This study aimed to evaluate periodontal tissue health in patients with chronic periodontitis, both with and without DM2 comorbidity. Periodontal microcirculation was examined using the Laser Doppler Flowmetry (LDF) technique, specifically with a LAKK-M device (Russia). A total of 106 patients were recruited and categorized into four groups based on their DM2 status and the severity of chronic periodontitis.Results. The study revealed group-specific differences in periodontal microcirculation parameters, analyzed through nonlinear dynamics. Notably, patients with chronic periodontitis and comorbid DM2 exhibited the most significant alterations. A phase portrait analysis further delineated the microcirculation health disparities between groups.Conclusion. There were marked differences in microcirculation health among chronic periodontitis patients with and without DM2 comorbidity, as evidenced by significant changes in the nonlinear dynamics-based phase portraits.

Speed-resolved perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning.

Laser speckle contrast imaging (LSCI) gives a relative measure of microcirculatory perfusion. However, due to the limited information in single-exposure LSCI, models are inaccurate for skin tissue due to complex effects from e.g. static and dynamic scatterers, multiple Doppler shifts, and the speed-distribution of blood. It has been demonstrated how to account for these effects in laser Doppler flowmetry (LDF) using inverse Monte Carlo (MC) algorithms. This allows for a speed-resolved perfusion measure in absolute units %RBC × mm/s, improving the physiological interpretation of the data. Until now, this has been limited to a single-point LDF technique but recent advances in multi-exposure LSCI (MELSCI) enable the analysis in an imaging modality. To present a method for speed-resolved perfusion imaging in absolute units %RBC × mm/s, computed from multi-exposure speckle contrast images. An artificial neural network (ANN) was trained on a large simulated dataset of multi-exposure contrast values and corresponding speed-resolved perfusion. The dataset was generated using MC simulations of photon transport in randomized skin models covering a wide range of physiologically relevant geometrical and optical tissue properties. The ANN was evaluated on in vivo data sets captured during an occlusion provocation. Speed-resolved perfusion was estimated in the three speed intervals 0 to , 1 to , and , with relative errors 9.8%, 12%, and 19%, respectively. The perfusion had a linear response to changes in both blood tissue fraction and blood flow speed and was less affected by tissue properties compared with single-exposure LSCI. The image quality was subjectively higher compared with LSCI, revealing previously unseen macro- and microvascular structures. The ANN, trained on modeled data, calculates speed-resolved perfusion in absolute units from multi-exposure speckle contrast. This method facilitates the physiological interpretation of measurements using MELSCI and may increase the clinical impact of the technique.

Endothelial dysfunction in subfertile women with polycystic ovary syndrome

Research questionIs there an association between post-occlusive reactive hyperaemia (PORH) and ovarian stimulation in women with normoandrogenaemic polycystic ovary syndrome (PCOS)? DesignWomen eligible for IVF at an academic fertility centre were invited to join this prospective study. Microvascular endothelial function was measured as PORH by laser Doppler flowmetry (LDF) before and after ovarian stimulation. Metabolic characteristics, hormone profiles and biochemical markers were analysed. ResultsThirty-four normoandrogenaemic women with PCOS and 36 normoandrogenaemic women without PCOS were included. The PCOS group displayed higher C-reactive protein levels and insulin resistance (P = 0.048 and P = 0.025, respectively). No significant difference was found in microcirculatory function between the groups at baseline. After ovarian stimulation, PORH was enhanced in the control group (slope 7.1 ± 3.3 versus 9.7 ± 4.5; P = 0.007; peak flow 30.7 ± 16.3 versus 43.5 ± 17.3, P = 0.008; however, the PCOS group experienced a blunting response to supraphysiological hormone status (slope 8.2 ± 5.1 versus 7.2 ± 4.3, P = 0.212; peak flow, 38.8 ± 19.4 versus 37.0 ± 21.8, P = 0.895). ConclusionsImpaired microcirculatory function could be found using a non-invasive LDF technique in normoandrogenaemic women with PCOS undergoing IVF, indicating early changes in vascular endothelial dysfunction. Future observational studies should clarify whether PORH measurement might help predict IVF prognosis or obstetric complications.

PHARMACOTHERAPY POSSIBILITIES OF CARDIOVASCULAR AUTONOMOUS NEUROPATHY IN CHILDREN WITH TYPE 1 DIABETES MELLITUS AT THE PRECLINICAL STAGE

The aim of the article is to evaluate the effectiveness of the thioctic acid preparation in the complex therapy of type 1 diabetes mellitus (T1DM) in children with cardiovascular autonomic neuropathy at the preclinical stage.Materials and methods. A design is a prospective randomized study. A clinical and instrumental examination of 64 children with preclinical stage signs of diabetic cardiovascular autonomic neuropathy (DCAN) was carried out. The cohort was divided into 2 groups: in the main and control groups, glycemic control was normalized by adjusting a dose of insulin therapy; in the main group, the children additionally received thioctic acid at the dose of 600 mg/day for 3 months. To control the effectiveness of the therapy, the technique of laser Doppler flowmetry was used.Results. After the pharmacological intervention, there was an improvement in the disease course, normalization of carbohydrate and lipid metabolism, increased vasomotor mechanisms of the regulation of the tissue blood flow due to an increase in endothelial and neurogenic kinds of activity in combination with a decrease in the intravascular tone and an increase in the effective perfusion in tissues. An increase in the heart rate variability was detected, positive dynamics of cardiovascular tests indicators according to D. Ewing, temporal (pNN50%, SDNN) and spectral indicators (VLF) were diagnosed. Achievement and maintenance of the target values of glycemic control indicators, as well as the absence of glycemic variability, turned out to be clinically significant for reducing the manifestations of neuropathy. The non-invasive technique of laser Doppler flowmetry is informative for the early diagnosis of DCAN in T1DM children.Conclusion. The carried out studies have demonstrated the effectiveness of the lipoic acid use at the dose of 600 mg/day for 3 months in the children with DCAN signs at the preclinical stage. The method of laser Doppler flowmetry for determining indications and monitoring the effectiveness of therapy makes it possible to implement a personalized approach to prescribing preventive treatment in T1DM children.

ISIT POSSIBLETO PREDICT POSTOPERATIVE ABDOMINAL COMPLICATIONS BYLASER DOPPLER FLOWMETRY?

In this study, the authors chose to assess the prognostic capabilities of the laser Doppler flowmetry method for postoperative complications in patients with advanced peritonitis. A retrospective randomized controlled trial (evidence level IIB) was performed. The study involved 54 patients who were operated on for secondary widespread fibrinous-purulent peritonitis. The patients were divided into two groups with 27 patients in each: the main group — with developed postoperative complications and a comparison group — without complications. The research was carried out by the analyzer "Lazma MC-1" (Russia). Scanning of the parietal and visceral peritoneum, small and large intestines, as well as the edges of the laparotomic wound was performed. A total of 504 scans were performed. The relationship of indicators was determined using the Spearman's rank correlation coefficient. Microcirculation indices in both groups were characterized by pronounced disorders of pre- and postcapillary resistance and disorders of tissue perfusion. The following indicators turned out to be statistically significant: percentage of microcirculation (r= 0.77 at p≤0.05), standard deviation (r = 0.67 at p≤0.05), coefficient of variation (r = 0.59 at p≤0, 05) and shunting percentage. In patients of the main group, the changes were expressed in an increase in pre- and postcapillary resistance, progressive arterio-venular shunting. All this ultimately led to disturbances in the perfusion of the intestinal wall, peritoneum and laparotomic wound, which led to postoperative complications. The technique of abdominal laser Doppler flowmetry can be a prognostic method that allows predicting the development of early postoperative complications after primary surgery and making appropriate adjustments to the treatment.

Peritoneal Laser Doppler Flowmetry in Predicting and Diagnosing Tertiary Peritonitis

Relevance. The article is devoted to one of the most difficult and controversial problems in the treatment of intra-abdominal infection, the prediction and diagnosis of tertiary peritonitis. The technique of peritoneal laser Doppler flowmetry (PLDF) makes it possible to assess the degree of visceral microcirculation disorders in various diseases of the abdominal organs.Aim of study. To identify early, trigger indicators of peritoneal microcirculation in tertiary peritonitis, obtained by the PLDF method.Material and methods. A retrospective analysis of the results of treatment of 48 patients operated on for secondary diffuse purulent peritonitis in the clinic of general surgery of the Astrakhan State Medical University in the period from 2015 to 2019 was carried out. All patients were divided into two equal groups: the main group with subsequently developed tertiary peritonitis, and the comparison group with arrested peritonitis. The study of peritoneal microcirculation was performed at the time of laparotomy, after debridement, 24 and 48 hours later. A total of 768 scans were performed. Evaluation was carried out using the APACHE II scales , abdominal index and SOFA scale. Spearman’s rank correlation test was one of the main statistical methods.Results. Twenty-four hours after the primary operation, the values of the percentage of microcirculation, standard deviation and coefficient of variation showed a direct correlation with the development of tertiary peritonitis. According to Spearman’s criterion, the closeness of the relationship according to these indicators was: r=0.71, r=0.55, r=0.63, respectively, at p≤0.05. After 48 hours, all the studied values of microcirculation made it possible to diagnose tertiary peritonitis. The data obtained correlated with the data obtained by the systems for assessing the severity of the patient’s condition.Conclusion. 1. The generally accepted scales for assessing the severity of patients’ condition (APACHE II, abdominal index and SOFA) used in patients with diffuse purulent peritonitis do not allow predicting the risk of tertiary peritonitis 24 hours after surgery. The data obtained as a result of the scoring on the above scales becomes representative 48 hours after the initial intervention. 2. The percentage of microcirculation, standard deviation and coefficient of variation can be used as early screening indicators of peritonetal laser Doppler flowmetry to predict tertiary peritonitis 24 hours after primary surgery. 3. The whole range of indicators of peritoneal laser Doppler flowmetry allows the degree of impairment of the tissue microcirculation in patients with peritonitis to be objectively assessed even 48 hours after the initial operation and to be diagnostic criteria of tertiary peritonitis.

Vascular reactivity of cutaneous circulation to brief compressive stimuli, in the human forearm.

A brief compressive stimulus is known to induce a rapid hyperemia in skeletal muscles, considered to contribute to the initial phase of functional hyperemia. Whether the same mechano-sensitivity characterizes the cutaneous circulation is debated. This study aims to investigate whether a rapid hyperemic response to compressive stimuli is also expressed by skin blood flow in humans. In 12 subjects, brief compressive stimuli were delivered to the forearm at varying pressures/durations (50/2, 100/2, 200/2, 200/1, 200/5mmHg/s); the sequence was randomized and repeated with the arm above and below heart level. Laser Doppler flowmetry technique was used to monitor skin blood flow. The response was described in terms of peak skin blood flow normalized to baseline (nSBFpeak), time-to-peak from the release of compression, and excess blood volume (EBV, expressed in terms of seconds of basal flow, s-bf) received during the response. The results consistently evidenced the occurrence of a compression-induced hyperemic response, with nSBFpeak = 2.9 ± 1.1, EBV = 17.0 ± 6.6s-bf, time-to-peak = 7.0 ± 0.7s (200mmHg, 2s, below heart level). Both nSBFpeak and EBV were significantly reduced (by about 50%) above compared to below heart level (p < 0.01). In addition, EBV slightly increased with increasing pressure (p < 0.05) and duration (p < 0.01) of the stimulus. For the first time, the rapid dilatator response to compressive stimuli was demonstrated in human cutaneous circulation. The functional meaning of this response remains to be elucidated.

A minimally invasive technique for serial intraosseous perfusion measurements in the murine tibia using laser Doppler flowmetry

In biomedical and preclinical research, the current standard method for measuring blood perfusion inside murine bone, radiolabeled microspheres, is a terminal procedure that cannot be used to monitor longitudinal perfusion changes. Laser Doppler flowmetry (LDF) can assess perfusion within the proximal tibial metaphysis of mice in vivo but requires a surgical procedure to place the measurement probe directly onto the bone surface. Sustained inflammation for over a month following this technique was previously reported, and previous studies have used LDF as an endpoint-only procedure. We developed a modified, minimally invasive LDF procedure to measure intraosseous perfusion in the murine tibia without stimulating local or systemic inflammation or inducing gait abnormalities. This modified technique can be used to measure perfusion weekly for up to at least a month in the murine tibia.•Unlike previous endpoint-only techniques, this modified LDF procedure can be performed weekly to monitor serial changes to intraosseous perfusion in the murine tibia•The modified LDF technique utilizes a smaller, more localized incision to minimize invasiveness and speed recovery

Minimally invasive laser Doppler flowmetry is suitable for serial bone perfusion measurements in mice

In vivo laser Doppler flowmetry (LDF) has previously been used to quantify blood perfusion accurately at a single timepoint in the murine tibial metaphysis. However, this procedure entailed substantial disruption to soft tissues overlying the bone and caused notable localized inflammation for several weeks after the procedure, impeding serial measurements in the same mouse. In this study, we tested a less invasive technique to measure perfusion in the tibia with LDF and determined that it can be used serially in the same mouse without causing signs of inflammation or gait perturbations. Twenty 14-week-old C57Bl/6J mice were evenly divided into groups that either had daily treadmill exercise or remained sedentary. Within these activity groups, mice were evenly subdivided into groups that received LDF measurements either weekly or only once at the study endpoint. Bone perfusion was measured with LDF in the anteromedial region of the right tibial metaphysis. Serum concentrations of interleukin 6, incision site wound area, and interlimb coordination during gait were measured weekly for four weeks. Tibial perfusion did not differ significantly between exercise and sedentary groups within the weekly or endpoint-only LDF groups at any timepoint. Perfusion was significantly increased in the third week in the weekly LDF group relative to measurements in the second and fourth weeks. Ligation of the femoral artery caused consistent, rapid reductions in tibial perfusion, validating that LDF is sensitive to changes in tibial blood supply. Weekly LDF procedures did not adversely affect gait, as interlimb coordination during treadmill locomotion was similar between weekly and endpoint-only LDF groups at every timepoint. Images of the incision site show wound closure within one week, and serum concentrations of interleukin 6 were not significantly different between weekly and endpoint-only groups. Together, these findings demonstrate that our minimally invasive LDF technique is suitable for serial in vivo measurements of intraosseous blood perfusion without inducing localized inflammation or negatively affecting gait patterns in mice.

Preclinical vascular alterations in obese adolescents detected by Laser-Doppler Flowmetry technique

Background and aimsChildhood obesity promotes adverse changes in cardiovascular structure and function. This study evaluated whether alterations in skin microcirculation were already present in obese adolescents in a pre-clinical phase of cardiovascular disease. Methods and resultsAfter an overnight fasting 22 obese adolescents and 24 normal-weight controls of similar age and gender distribution underwent clinical and blood examination and assessment of microvascular function by using two non-invasive techniques such as Peripheral Artery Tonometry (PAT) and Laser-Doppler Flowmetry (LDF).As compared to normal weight subjects, obese children had higher blood pressure, were significantly more hyper-insulinemic and insulin resistant, showing significantly higher plasma total cholesterol, LDL cholesterol, triglycerides and alanine aminotransferase (ALT).LDF showed lower pre- and post-occlusion forearm skin perfusion (perfusion units/second (PU/sec); median [IQR]) in obese than in normal weight subjects (pre-occlusion: 1633.8 [1023.5] vs. 2281.1 [1344.2]; p = 0.015. Post-occlusion: 4811.3 [4068.9] vs. 7072.8 [7298.8]; p = 0.021), while PAT revealed similar values of reactive hyperemia index (RHI).In entire population, fat mass % (FM%) was an independent determinant of both pre-and post-occlusion skin perfusion. Finally, being obese was associated with a higher risk to have a reduction of both pre- and post-occlusion skin perfusion (OR = 5,82 and 9,27, respectively). ConclusionLDF showed very early, pre-clinical, vascular involvement in obese adolescents, characterized by impaired skin microcirculation, possibly reflecting a more diffuse microvascular dysfunction to other body tissues. Whether changing life style and improving weight may reverse such pre-clinical alterations remains to be established.

Characterization of Microvascular Post Occlusive Hyperemia Using Laser Doppler Flowmetry Technique in Subjects With Cardiometabolic Disorders.

Laser Doppler flowmetry (LDF) provides a noninvasive real-time quantification of relative changes in cutaneous perfusion. Assessment of the microvascular function can provide information on the development of various cardiometabolic disorders. In recent years, non-invasive measurements have gain attention, due to the potential complications associated to invasive procedures. To differentiate the microvascular function between subjects with cardiometabolic disorders and healthy controls. Evaluation through LDF during post-occlusive reactive hyperemia (PORH) in patients with or without history of cardiometabolic disorders. Peak values of microvascular flow during post-occlusive reactive hyperemia and both upload and recovery slopes were lesser in the pathological group. A novel approach to characterize LDF during PORH was useful to differentiate patients with cardiometabolic disorders from healthy subjects.

Machine learning in multiexposure laser speckle contrast imaging can replace conventional laser Doppler flowmetry.

.Laser speckle contrast imaging (LSCI) enables video rate imaging of blood flow. However, its relation to tissue blood perfusion is nonlinear and depends strongly on exposure time. By contrast, the perfusion estimate from the slower laser Doppler flowmetry (LDF) technique has a relationship to blood perfusion that is better understood. Multiexposure LSCI (MELSCI) enables a perfusion estimate closer to the actual perfusion than that using a single exposure time. We present and evaluate a method that utilizes contrasts from seven exposure times between 1 and 64 ms to calculate a perfusion estimate that resembles the perfusion estimate from LDF. The method is based on artificial neural networks (ANN) for fast and accurate processing of MELSCI contrasts to perfusion. The networks are trained using modeling of Doppler histograms and speckle contrasts from tissue models. The importance of accounting for noise is demonstrated. Results show that by using ANN, MELSCI data can be processed to LDF perfusion with high accuracy, with a correlation coefficient for noise-free data, when a moderate degree of noise is present, and for in vivo data from an occlusion-release experiment.

Wavelet Phase Coherence Analysis between the Respiratory Activity and the Microcirculation—The Effects of Type 1 Diabetes

The microvascular perfusion is modulated by physiological functions, which have been associated with specific frequency ranges. Although cardio-respiratory interactions have been widely analyzed at a macrocirculation level, only few studies have been conducted with the aim to understand the effect of breathing on the peripheral circulation. Diabetic microangiopathy is characterized by structural and functional alterations of the blood microvessels, which reflect in a modification of the physical properties of peripheral microvascular beds, such as vascular stiffness. A wavelet phase coherence (WPC) analysis was performed to elucidate the time-phase relationship between the respiratory activity and vascular-dependent features of the peripheral pulse, reconstructed by means of a novel multi-Gaussian modeling algorithm. The present WPC analysis was conducted on a group of 24 healthy volunteers, mean age 30±15 years, in comparison with 21 type-1 diabetic (T1D) subjects, mean age 26±3 years, in order to detect the effects of T1D on the physiological coupling between breathing and microcirculation. The peripheral cutaneous perfusion was assessed on the pulp of the index finger with the laser Doppler flowmetry (LDF) technique, while the respiratory signal was simultaneously recorded with a wearable chest band. In 17 out of the 24 control subjects involved (i.e., 71%), significant WPC values were identified in the respiratory frequency range (0.145-0.6 Hz), with respect to the area beneath the diastolic portion of the peripheral pulse (median WPC: 77.9%). This outcome indicates that the diastolic phase of the pulse exhibits a marked periodicity linked to the breathing activity. The analysis conducted on the T1D group highlighted a loss of synchronization, with significant WPC levels found in only 33% of the investigated subjects. These results suggest that the proposed method is able to detect the detrimental effects of T1D on the blood microcirculation. Disclosure A. Perrella: None. M. Sorelli: None. P. Francia: None. L. Capirchio: None. R. Anichini: Advisory Panel; Self; Abbott. Speaker's Bureau; Self; Novartis Pharmaceuticals Corporation, Boehringer Ingelheim GmbH. Advisory Panel; Self; Eli Lilly and Company, AstraZeneca. Speaker's Bureau; Self; Merck &amp; Co., Inc., Takeda Development Centre Europe Ltd.. Advisory Panel; Self; Sanofi, Janssen Pharmaceuticals, Inc.. Research Support; Self; Grünenthal Group. A. de Bellis: Speaker's Bureau; Self; Eli Lilly and Company, AstraZeneca, Novo Nordisk A/S. Research Support; Self; Grünenthal Group. M. Gulisano: None. L. Bocchi: None.

Microcirculation in patients with paranoid schizophrenia

To study microcirculation in patients with paranoid schizophrenia by laser Doppler flowmetry. Fifty-three patients at the age from 18 to 38 years with a diagnosis of 'paranoid schizophrenia' (F20.0) were examined in the acute psychotic state and after 3 weeks of therapy. The control group consisted of 20 healthy volunteers. To assess microcirculation, the noninvasive technique of laser Doppler flowmetry using a laser blood flow analyzer was used. Significant changes in the microcirculation persisting even over three weeks of therapy in patients were identified. The total microcirculation index was increased by 1.4 times which indicated the acceleration of blood flow. An increase in the average fluctuations of perfusion by 3.7 times and in the coefficient of variation by 1.9 times, which reflect the excessive strengthening of local mechanisms of regulation of microcirculation, were found. There were an increase in the myogenic tone and neurogenic tone of metarteriole and precapillary sphincters as well as bypass index.

The application of combined low-intensity laser therapy for the treatment of the patients presenting with trophic ulcers associated with chronic venous insufficiency of the lower extremities

The objective of the present study was the evaluation of the effectiveness of the combined treatment of the patients presenting with trophic ulcers associated with chronic venous insufficiency of the lower extremities of venous etiology with the application of low-intensity laser therapy (LILT) at different wavelengths. The study included the patients presenting with chronic venous insufficiency (CVI) (class C6 in accordance with the CEAP clinical classification). The ultrasonic Doppler examination (USDG) of the lower extremities revealed valvular insufficiency in the saphenous veins in 98.8% of the examined patients, in the deep venous system in 58% of them, and in the perforating veins in 72% of the cases. The laser Doppler flowmetry technique was used to assess the state of the microcirculation. Group 1 was comprised of 34 (43.59%) patients undergoing the traditional conservative treatment that consisted of pharmacotherapy (including antibiotic therapy, depending on the sensitivity of microflora assessed by the culture technique), the local treatment in the form of dressing in compliance with the standard surgical treatment schemes depending on the phase of the wound healing process, and elastic compression of the lower extremities. The main group 2 consisted of 44 patients (56.41%) who were treated, in addition to the traditional conservative therapy, with the use of LILT according to the new technique that combines the external laser exposure of the trophic ulcer region using the 'LASMIK' laser device during a single 2 minute session per zone in the pulsed mode (light pulse duration of 100-130 ns, frequency 80 Hz), at a wavelength of 635 nm, by a matrix emitter (consisting of eight laser diodes with the surface area of 8 cm2), at a distance up to 7 cm, with pulsed power of 40 W, power density of 5 W/cm2, and the intravenous laser blood illumination (fiber output power 2 mW) with a wavelength of 365 nm (UV range) and 525 nm (green spectrum) alternately, every other day. Each patient underwent 12 daily procedures per course. Combined low-intensity laser therapy promoted the rapid recovery of the sympathetic regulation of the microvascular tone and normalization of arteriolar-venular relationships which contributed to the improvement of blood supply to the tissues, the reduction of inflammation, enhanced activation of the reparative processes, and acceleration of epithelialization of trophic ulcerous defects. The combined strategy makes it possible to carry out the more effective treatment of the patients presenting with trophic ulcers with the three-fold reduction of the ulcer healing time and the pronounced stimulation of the persistent adaptation of the physiological responses preventing the development of the relapses.

Conjecture on reflectionlessness of blood-vascular system as a wave-conducting medium

Our research is related to the employment of photoplethysmography (PPG) and laser Doppler flowmetry (LDF) techniques (measuring the blood volume and flux, respectively) for the peripheral vascular system. We derive the governing equations of the wave dynamics for the case of extremely inhomogeneous parameters. We argue for the conjecture that the blood-vascular system as a wave-conducting medium should be nearly reflection-free. With the reflectionlessness condition, one can find the general solution to the governing equation and, on the basis of this solution, analyse the relationships between PPG- and LDF-signals.

17β-Estradiol prevents mesenteric injury induced by occlusion of the proximal descending aorta in male rats

ObjectiveIn surgical aortic repair or cardiac surgery with aorta occlusion, the occurrence of mesenteric ischemia and bowel injury has been associated with higher short-term mortality. The vascular protection of estrogens has been investigated and is mainly mediated by increasing the availability of nitric oxide (NO). Therefore, this study investigated the role of 17β-estradiol on visceral ischemia-reperfusion (I/R) injury after descending aorta occlusion in male rats. MethodsMesenteric ischemia was induced in male Wistar rats by placing a 2F Fogarty arterial embolectomy catheter (Edwards Lifesciences, Irvine, Calif) in the descending aorta, which remained occluded for 15 minutes, followed by reperfusion for up to 2 hours. Rats were divided into four groups: (1) rats that underwent surgical manipulation only (sham, n = 22); (2) rats that underwent I/R injury (n = 22); (3) rats treated with intravenous 17β-estradiol (280 μg/kg) 30 minutes before I/R (n = 22); (4) or at the beginning of reperfusion (n = 22). Intestinal histopathologic changes were evaluated by histomorphometry. Mesenteric microcirculatory alterations were assessed by laser Doppler flowmetry and intravital microscopy technique. Protein expression of intercellular adhesion molecule-1, P-selectin, endothelial NO synthase (eNOS), and endothelin-1 was evaluated by immunohistochemistry; in addition, eNOS and endothelin-1 gene expressions were quantified by real-time polymerase chain reaction. Serum cytokines were measured by enzyme-linked immunosorbent assay. ResultsRelative to the sham group, the I/R group exhibited a highly pronounced loss of intestine mucosal thickness, a reduction in mesenteric blood flow (P = .0203), increased migrated leukocytes (P < .05), and high mortality rate (35%). Treatment with 17β-estradiol before aorta occlusion preserved intestine mucosal thickness (P = .0437) and mesenteric blood flow (P = .0251), reduced the number of migrated leukocytes (P < .05), and prevented any fatal occurrence. Furthermore, 17β-estradiol downregulated the expression of intercellular adhesion molecule-1 (P = .0001) and P-selectin (P < .0001) on the endothelium and increased the protein expression of eNOS (P < .0001). The gene expressions of eNOS and endothelin-1 did not differ between the groups. ConclusionsThe prophylactic treatment with 17β-estradiol showed better overall repercussions and was able to prevent any fatal occurrence, increase eNOS expression, thus preserving mesenteric perfusion and intestinal integrity, and reduce inflammation.

Increase of cortical cerebral blood flow and further cerebral microcirculatory effects of Serelaxin in a sheep model.

Serelaxin, recombinant human relaxin-2, modulates endothelial vasodilatory functionality and is under evaluation for treatment of acute heart failure. Little is known about acute effects on cerebral perfusion. We tested the hypothesis that Serelaxin might also have effects on the cerebral microcirculation in a sheep model, which resembles human brain structure quite well. We used laser Doppler flowmetry and sidestream dark-field (SDF) imaging techniques, which are reliable tools to continuously assess dynamic changes in cerebral perfusion. Laser Doppler flowmetry shows that bolus injection of 30 μg Serelaxin/kg body wt induces an increase (P = 0.006) to roughly 150% of cortical cerebral blood flow (CBF), whereas subcortical CBF remains unchanged (P = 0.688). The effects on area-dependent CBF were significantly different after the bolus injection (P = 0.042). Effects on cortical CBF were further confirmed by SDF imaging. The bolus injection of Serelaxin increased total vessel density to 127% (P = 0.00046), perfused vessel density to 145% (P = 0.024), and perfused capillary density to 153% (P = 0.024). Western blotting confirmed the expression of relaxin receptors RXFP1 and truncated RXFP2-variants in the respective brain regions, suggesting a possible contribution of RXFP1 on the effects of Serelaxin. In conclusion, the injection of a high dose of Serelaxin exerts quick effects on the cerebral microcirculation. Therefore, Serelaxin might be suitable to improve cortical microcirculation and exert neuroprotective effects in clinically relevant scenarios that involve cortical hypoperfusion. These findings need to be confirmed in relevant experimental settings involving cerebral cortical hypoperfusion and can possibly be translated into clinical practice.

Diabetic choroidopathy: a review of the current literature.

Diabetic retinopathy is an increasingly prevalent disease, and a leading contributor to the burden of all-cause blindness worldwide. In addition to retinal changes, choroidal abnormalities are common in patients with diabetes. The first studies concerning this vascular structure were based on histologic, indocyanine angiography and laser Doppler flowmetry techniques, but the development of new optical coherence tomography (OCT) technologies and imaging software for enhanced depth imaging (EDI)-OCT in recent years has made it possible to provide more detailed images of the choroidal anatomy and topography.In diabetic patients, several choroidal changes have been described in the literature throughout the years; the recent focus is choroidal thickness, which is significantly different from that in healthy patients. However, understanding choroidal manifestations of diabetic eye disease remains a real challenge, and this gap is hindering efforts towards better defining choroidal evaluation as a predictive factor for disease evolution and treatment response.This review aims to summarize the recent literature concerning changes in choroidal structure in diabetic patients, the relationship to diabetic retinal disease progression, and finally, the current and potential application of the measurement of variations in choroidal thickness for patient management.

Local Thermal Impact on Microcirculation Assessed by Imaging Photoplethysmography

Laser Doppler Flowmetry and Laser Speckle Contrast Imaging are applied usually for assessment of parameters of the cutaneous blood flow during thermoregulation. Alternatively, this work explores the feasibility of blood pulsation imaging under incoherent green illumination for measuring the response of human body on local thermal impact. The proposed technique allows assessment of the cutaneous blood flow changes during thermoregulation simultaneously in different areas of the body. The preliminary experiments show that the blood pulsation amplitude (BPA) is sufficiently reliable index, which could characterize the relative change of the cutaneous blood flow similarly to the parameter measured with the Laser Doppler Flowmetry technique. It is shown that BPA grows up proportionally to the skin temperature increase in the preliminary cooled finger, whilst it is in the steady state in another finger having the constant temperature. The rate of BPA increase is individual characteristic of a subject, which could serve as a parameter of the subject’s vasomotor reactivity on the temperature changes. High quality of visualized distribution of blood pulsations, good repeatability of the BPA, and revealed dependencies of its response on the skin-temperature change offer the prospect for development new system of studying microcirculation.