Search Results (46)

This study addresses the challenge of rapidly and accurately distinguishing zones of microbial activity from antibiotic inhibition zones in Petri dishes. We propose a laser speckle imaging technique enhanced with subpixel correlation analysis to monitor dynamic changes in the inhibition zone surrounding an antibiotic disc. This method provides faster results compared to the standard disk diffusion assay recommended by EUCAST. To enable automated analysis, we used machine learning algorithms for classifying areas of bacterial or fungal activity versus inhibited growth. Classification is performed over short time windows (e.g., 1 h), supporting near-real-time assessment. To further improve accuracy, we introduce a correction method based on the known spatial dynamics of inhibition zone formation. The novelty of the study lies in combining a speckle imaging subpixel correlation algorithm with ML classification and with pre- and post-processing. This approach enables early automated assessment of antimicrobial effects with potential applications in rapid drug susceptibility testing and microbiological research. Full article

Introduction: Ehlers–Danlos Syndromes (EDSs) are a heterogeneous group of monogenic connective tissue disorders (e.g., joint hypermobility and dislocation, skin hyperelasticity and fragility, chronic pain, delayed wound healing process,, etc.). The primary objective of this study was to present a specialized therapeutic wound management process for a burn-injured female patient diagnosed with EDS. Case Presentation: A 34-year-old female patient presented with extensive thermal burns (biofireplace explosion). The patient had a family history of diagnosed EDS. Additionally, the patient was in a poor mental condition and, since 2020, had been undergoing pharmacotherapy with antidepressant and anti-anxiety medication. This might be the first such clinical observation in the world, but a correlation has been observed between psychiatric medication use and EDS wound healing impairment. During the hospitalization process, the patient underwent a series of surgeries aimed at the fastest and most effective closure of wounds. The patient, after 182 days of hospitalization in our facility, was discharged home. Materials and Methods: During the patient’s hospital stay, the patient underwent multiple procedures involving debridement of necrotic tissues. Additionally, allogeneic acellular dermal matrix (ADM) grafting was performed on the wounds, and a procedure was conducted in which skin was grafted using the MEEK technique. The in vitro cultured skin cells, as the advanced therapy medicinal products (ATMPs), were used. During the patient’s stay in the hospital, images were taken using low-energy laser speckle contrast analysis (LASCA) to asses microperfusion or lack thereof. The measurements were taken at intervals of several days. Conclusions: The treatment of burn wounds in patients with EDS requires a long hospitalization period. It also may require a multi-stage approach utilizing innovative preparations (e.g., ADMs and ATMPs). The assessment of wound healing progress can be performed using advanced equipment, such as laser speckle contrast analysis (LASCA). Full article

Background/Objectives: Reperfusion is a major determinant of skin graft viability. The contributions of the perfusion status of the wound bed, wound margin, and donor skin to the success of the skin graft are unclear. We aimed to evaluate the relationship between perfusion variables and graft necrosis extension on the scalp and lower limb. Methods: A prospective study was conducted on adults undergoing skin graft closure after skin cancer excision on the scalp (n = 22) and lower limb (n = 20). Perfusion was measured intraoperatively and non-invasively with laser speckle contrast imaging on the graft bed, margin, and donor skin. By day 28, graft necrosis extension was quantified. Results: On the scalp and lower limb, graft bed perfusion very strongly correlated with necrosis extension (r = −0.82, p < 0.001 and r = −0.94, p < 0.001, respectively). A significant correlation (r = −0.57, p = 0.01) between margin perfusion and necrosis extension was only observed on the lower limb. The donor skin perfusion and necrosis extension did not correlate in either location (p > 0.05). The graft bed perfusion explained 68% and 89% of the variation in necrosis extension on the scalp and lower limb, respectively. Regression models of necrosis extension based on graft bed perfusion were obtained. For each unit increase in the perfusion of the graft bed, a similar decrease in necrosis extension was observed on the scalp and lower limb (40 and 48 percentage points, respectively). Conclusions: Unlike the perfusion of the wound margin and donor skin, wound bed perfusion plays a significant role in skin graft viability and can predict necrosis extension. Full article

The development of affordable and reliable methods for quantitative determination of stable atomic nuclei in aqueous solutions and adjuvant agents used in tumor chemotherapy is an important task in modern pharmaceutical chemistry. This work quantified the deuterium/prothium isotope ratio in aqueous solutions through an original two-dimensional diffuse laser scattering (2D-DLS) software and hardware system based on chemometric processing of discrete interference patterns (dynamic speckle patterns). For this purpose, 10 mathematical descriptors (d_i), similar to QSAR descriptors, were used. Correlation analysis of bivariate “log d_i—D/H” plots shows an individual set of multi-descriptors for a given sample with a given D/H ratio (ppm). A diagnostic sign (DS) of differentiation was established: the samples were considered homeomorphic if 6 out of 10 descriptors differed by less than 15% (n ≥ 180). The analytical range (r = 0.987) between the upper (D/H ≤ 2 ppm) and lower (D/H = 180 ppm) limits for the quantification of stable hydrogen nuclei in water and aqueous solutions were established. Using the Spirotox method, a «safe zone» for protozoan survival was determined between 50 and 130 ppm D/H. Here, we discuss the dispersive (DLS, LALLS) and optical properties (refractive index, optical rotation angle) of the solutions with different D/H ratios that define the diffuse laser radiation due to surface density inhomogeneities. The obtained findings may pave the way for the future use of a portable, in situ diffuse laser light scattering instrument to determine deuterium in water and aqueous adjuvants. Full article

Speckles are inherent in structured laser-based light projection using diffractive optics such as metasurfaces or diffractive optical elements (DOEs). One application of structured light is to provide illumination for machine vision and depth sensing. This is particularly attractive for mobile or low-power applications, where metasurfaces provide a compact, customizable solution, which can furthermore reach extreme field of illuminations. However, the speckles might limit detection capabilities by, e.g., lowering the detection range or providing false results. In this work, we present a series of measurements with matching simulations on a 70 × 50 degrees diffractive diffuser using different light sources (varying divergence angles + VCSEL array) to quantify the impact of speckles. We observe a qualitative agreement in speckle correlation between the measurements and the simulations and explain, in part using cross-correlation for analysis, why we do not observe the same speckle pattern between the measurements and the simulations. By performing extra simulations, we conclude that by only changing the light source, there is a limit to the reduction of the speckle contrast which, we can achieve, and, to reduce it further, alternative approaches such as changing the design method of the diffractive diffuser must be harnessed. Full article

Background: It is established that diabetes mellitus (DM) is characterized by increased cardiovascular risk associated with subclinical atherosclerosis as well as microvascular alterations. Laser speckle contrast analysis (LASCA) is an innovative, non-invasive method for assessing skin microvascular function. Objectives: We sought to assess skin microvascular function in patients with type 2 DM and matched controls. Methods: Consecutive patients with DM and individuals matched for age, sex and BMI were included in the study. Skin microvascular perfusion was assessed, using LASCA, during baseline, a 5 min occlusion period and a 5 min reperfusion period. Carotid intima-media thickness (cIMT) was measured as a surrogate marker of macrocirculation. Results: In total, 18 patients with DM and 22 in the control group were enrolled. No statistically significant differences were observed in baseline flux, peak flux and percentage decrease during arterial occlusion. During reperfusion, individuals with DM exhibited a smaller peak magnitude compared to controls (147.0 ± 64.7% vs. 189.4 ± 46.0%, respectively; p < 0.05). Moreover, cIMT was higher in patients with DM compared to controls (0.68 ± 0.09 mm vs. 0.60 ± 0.08 mm, respectively, p < 0.01) and was negatively correlated with skin microvascular reactivity in the univariate analysis. In the multivariate analysis, glucose and office systolic blood pressure levels remained significant predictors of microvascular reactivity. Conclusions: Our study shows that patients with type 2 DM exhibit impaired skin microvascular function compared to controls. Furthermore, glucose levels and blood pressure play a key role in microvascular dysfunction. However, additional studies are needed to address the clinical significance of early microvascular changes in DM. Full article

Scattering materials have been of considerable research interest due to their unique optical properties that may enable applications throughout the area of disordered photonics, particularly in fields such as Random Lasers, nonlinear (NL) microscopy in biomedical research, and optical thermometry. However, the complex structures of these materials make traditional NL spectroscopic techniques unsuitable for studies, as the materials of interest can cause large multiple scattering of light in addition to presenting spatial heterogeneities. Fortunately, new techniques, such as the Scattered Light Imaging Method (SLIM), the Intensity Correlation scan (IC-scan), and the Reflection Intensity Correlation scan (RICO-scan), have recently emerged, providing researchers with more appropriate ways to study disordered and scattering NL materials. These techniques allow for a deeper characterization of the NL optical properties of highly scattering materials, which are essential for applications in photonics, optoelectronics, and biophotonics, for example. In this paper, we discuss these innovative techniques, which can offer insights into the properties of materials of great potential for disordered photonics. Full article

Background: Systemic lupus erythematosus (SLE) is a prototype autoimmune disease associated with increased cardiovascular (CV) burden. Besides increased arterial stiffness and subclinical atherosclerosis, microvascular dysfunction is considered an important component in the pathophysiology of CV disease. However, there is a lack of data regarding the effect of multiple target organ damage (TOD) on CV health. Objectives: This study aimed to evaluate (i) the presence of microvascular changes in SLE in various vascular beds, (ii) the possible associations between the accumulation of microvascular TOD and CV risk and (iii) whether Galectin-3 represents a predictor of combined microvascular TOD. Methods: Participants underwent (i) evaluation of skin microvascular perfusion (laser speckle contrast analysis), (ii) fundoscopy (non-mydriatic fundus camera), (iii) indirect assessment of myocardial perfusion (subendocardial viability ratio) and (iv) determination of urine albumin-to-creatinine ratio (UACR). CV risk was calculated using the QResearch Risk Estimator version 3 (QRISK3). Serum Galectin-3 levels were determined. Results: Forty-seven SLE patients and fifty controls were studied. SLE patients demonstrated impaired skin microvascular reactivity (160.2 ± 41.0 vs. 203.6 ± 40.1%), retinal arteriolar narrowing (88.1 ± 11.1 vs. 94.6 ± 13.5 μm) and higher UACR levels compared to controls. Furthermore, SLE individuals had significantly higher Galectin-3 levels [21.5(6.1) vs. 6.6(6.6) ng/dL], QRISK3 scores [7.0(8.6) vs. 1.3(3.6)%] and a greater chance for microvascular dysfunction. In the SLE group, patients with multiple TOD exhibited higher QRISK3. In the multivariate analysis, the accumulation of TOD correlated with disease activity and Galectin-3 (p < 0.05). Conclusions: Our study showed for the first time that SLE patients exhibit a greater number of cases of TOD. The accumulation of TOD was associated with increased CV risk. Clinicians dealing with SLE should be aware and seek microvascular alterations. Full article

The characterization of landslides located in remote areas poses significant challenges due to the costs of reaching the sites and the lack of reliable subsurface data to constrain geological interpretations. In this paper, the advantages of combining field and remote sensing techniques to investigate the deformation and stability of rock slopes are demonstrated. The characterization of the Fels landslide, a large, slowly deforming rock slope in central Alaska, is described. Historical aerial imagery is used to highlight the relationship between glacier retreat and developing instability. Airborne laser scanning (ALS) and Structure-from-Motion (SfM) datasets are used to investigate the structural geological setting of the landslide, revealing a good agreement between structural discontinuities at the outcrop and slope scales. The magnitude, plunge, and direction of slope surface displacements and their changes over time are studied using a multi-temporal synthetic aperture radar speckle-tracking (SAR ST) dataset. The analyses show an increase in displacement rates (i.e., an acceleration of the movement) between 2010 and 2020. Significant spatial variations of displacement direction and plunge are noted and correlated with the morphology of the failure surface reconstructed using the vector inclination method (VIM). In particular, steeper displacement vectors were reconstructed in the upper slope, compared to the central part, thus suggesting a change in basal surface morphology, which is largely controlled by rock mass foliation. Through this analytical approach, the Fels landslide is shown to be a slow-moving, compound rockslide, the displacement of which is controlled by structural geological features and promoted by glacier retreat. Full article

Diffuse correlation spectroscopy is a non-invasive optical modality used to measure cerebral blood flow in real time, and it has important potential applications in clinical monitoring and neuroscience. As such, many research groups have recently been investigating methods to improve the signal-to-noise ratio, imaging depth, and spatial resolution of diffuse correlation spectroscopy. Such methods have included multispeckle, long wavelength, interferometric, depth discrimination, time-of-flight resolution, and acousto-optic detection strategies. In this review, we exhaustively appraise this plethora of recent advances, which can be used to assess limitations and guide innovation for future implementations of diffuse correlation spectroscopy that will harness technological improvements in the years to come. Full article

Background and Objectives: To investigate peripheral blood flow in retinal vessels and vessel diameters after intravitreal ranibizumab injection (IRI) and the relationship between these parameters and cytokines in branch retinal vein occlusion (BRVO) with macular edema. Materials and Methods: We assessed relative flow volume (RFV) and the width of the main and branch retinal arteries and veins in the occluded and non-occluded regions before and after IRI in 37 patients with BRVO and macular edema. Measurements were made using laser speckle flowgraphy (LSFG). When performing IRI, we obtained samples of aqueous humor and analyzed them using the suspension array method to evaluate vascular endothelial growth factor (VEGF), placental growth factor (PlGF), platelet-derived growth factor (PDGF)-AA, soluble intercellular adhesion molecule (sICAM)-1, monocyte chemoattractant protein 1 (MCP-1), interleukin (IL)-6, IL-8, and interferon-inducible 10-kDa protein (IP-10). Results: In both retinal regions, before and after IRI, the RFV in the main artery and vein showed a significant correlation with the summed RFV in the respective branch vessels 1 and 2. In the occluded region, the RFV in the main vein was significantly negatively correlated with MCP-1, PDGF-AA, IL-6, and IL-8; the RFV in branch vein 1 was significantly negatively correlated with PlGF, MCP-1, IL-6, and IL-8; PDGF-AA was significantly negatively correlated with the width of the main and branch veins; and the RFVs of the main artery and vein decreased significantly from before to 1 month after IRI. Conclusions: Contrary to expectations, the study found that anti-VEGF therapy does not affect RFV in arteries and veins in patients with BRVO and macular edema. Furthermore, retinal blood flow is poor in patients with high MCP-1, IL-6, and IL-8. Finally, high PDGF-AA may result in smaller venous diameters and reduced retinal blood flow. Full article

The modal parameters of structures, and in particular their mode shapes, are generally determined based on the measurement of accelerometers or laser vibrometers. However, these sensors do not allow the performance of full-field measurements. In this study, the free vibration of a beam triggered by a shock is investigated using a high-speed camera with high image definition. With the help of digital image correlation (DIC), the beam displacement fields are deduced from the images. To analyse the DIC measurement quality, different tests and analyses are performed. First, the systematic errors and uncertainties in the DIC calculation for a simple translation are analysed considering different speckles. Then, tests on two configurations of a vibrating beam are filmed and full-field displacement measurements are computed. The modal parameters of the beam are deduced from these measurements using a continuous wavelet transform method. Particular care was taken to adapt the method to the post-processing of the numerous and noisy signals obtained for these experiments. All the steps of the post-processing are detailed in this paper. Finally, the modal parameters obtained with the proposed method are compared with those obtained in a more classical way using accelerometers and from the beam theory. In particular, the comparison of the signal-to-noise ratio of the different measurement methods is discussed. Full article

Using laser speckle flowgraphy (LSFG), we investigated the time course of changes in choroidal circulation hemodynamics after a cold pressor test in healthy eyes. This prospective study included the right eye of 19 young healthy participants. The macular mean blur rate (MBR) was measured with LSFG. The MBR, intraocular pressure (IOP), systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), mean blood pressure (MBP), and ocular perfusion pressure (OPP) were evaluated at baseline; immediately after the test and 10, 20, and 30 min later. Immediately after the test (0 min), SBP, DBP, MBP, and OPP were significantly elevated compared with those at baseline. The macular MBR significantly increased by +10.3 ± 7.1% immediately after the test. However, there was no change after 10, 20, and 30 min in the above parameter. A significant positive correlation of the macular MBR with the SBP, MBP, and OPP was observed. In young healthy individuals, increased sympathetic activity induced by a cold pressor test increases choroidal hemodynamics in the macula along with an increase in systemic circulatory dynamics, which normalizes after 10 min. Therefore, LSFG may provide a novel approach for assessing sympathetic activity and intrinsic vascular responsiveness in the eye. Full article

(1) Background: Irritable bowel syndrome (IBS) is a global public health problem, the pathogenesis of which has not been fully explored. Limiting fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) can relieve symptoms in some patients with IBS. Studies have shown that normal microcirculation perfusion is necessary to maintain the primary function of the gastrointestinal system. Here, we hypothesized that IBS pathogenesis might be related to abnormalities in colonic microcirculation. A low-FODMAP diet could alleviate visceral hypersensitivity (VH) by improving colonic microcirculation; (2) Methods: C57BL/6 mice were raised to establish an IBS-like rodent model using water avoidance (WA) stress or SHAM-WA as a control, one hour per day for ten days. The mice in the WA group were administered different levels of the FODMAP diet: 2.1% regular FODMAP (WA-RF), 10% high FODMAP diet (WA-HF), 5% medium FODMAP diet (WA-MF), and 0% low FODMAP diet (WA-LF) for the following 14 days. The body weight and food consumption of the mice were recorded. Visceral sensitivity was measured as colorectal distention (CRD) using the abdominal withdrawal reflex (AWR) score. Colonic microcirculation was assessed using laser speckle contrast imaging (LCSI). Vascular endothelial-derived growth factor (VEGF) was detected using immunofluorescence staining; (3) Results: The threshold values of CRD pressure in the WA-RF, WA-HF, and WA-MF groups were significantly lower than those in the SHAM-WA group. Moreover, we observed that colonic microcirculation perfusion decreased, and the expression of VEGF protein increased in these three groups of mice. Interestingly, a low-FODMAP dietary intervention could reverse this situation. Specifically, a low-FODMAP diet increased colonic microcirculation perfusion, reduced VEGF protein expression in mice, and increased the threshold of VH. There was a significant positive correlation between colonic microcirculation and threshold for VH; (4) Conclusions: These results demonstrate that a low-FODMAP diet can alter VH by affecting colonic microcirculation. Changes in intestinal microcirculation may be related to VEGF expression. Full article

Dynamic laser speckle (DLS) analysis is a very sensitive technique to measure biological activity within samples. In agriculture, the technique is applied to monitor seed germination, but external light, water content, and pigments affect the measurements. DLS systems use visible light sources, typically red lasers, which may exacerbate their influences. The main objective of this work is to assess whether infrared (IR) lasers improve the robustness of DLS measurements in seed germination applications. We develop a system where DLS analysis can be performed simultaneously on visible and IR light. Using the system, we quantify how the DLS signal is affected by pigments and scattering. The results show that the use of IR light reduces the variability of the measurements acquired. DLS systems based on IR light appear to be less sensitive to pigments, and the greater penetration of IR light into samples, which is due to reduced scattering, may contribute to the signal collected being correlated to relevant biological processes within the inner tissue. Additionally, water activity provides less influence on the DLS signal when an IR laser is used. These findings support the wider use of IR lasers in DLS-based instruments for applications in biological samples. Full article