Multimodal optical clearing to minimize light attenuation in biological tissues.

The biggest obstacle to optical imaging is light attenuation in biological tissues. Conventional clearing techniques, such as agent-based clearing, improve light penetration depth by reducing scattering, but they are hampered by drawbacks including toxicity, low efficiency, slowness, and superficial performance, which prevent them from resolving the attenuation problem on their own. Therefore, quick, safe, and effective procedures have been developed.

Method for tissue clearing: temporal tissue optical clearing.

Light absorption and scattering in biological tissue are significant variables in optical imaging technologies and regulating them enhances optical imaging quality. Optical clearing methods can decrease light scattering and improve optical imaging quality to some extent but owing to their limited efficacy and the potential influence of optical clearing agents on tissue functioning, complementing approaches must be investigated. In this paper, a new strategy of optical clearing proposed as time-dependent or temporal tissue optical clearing (TTOC) is described.

The effect of trehalose administration on vascular inflammation in patients with coronary artery disease.

Background: In recent years, several trials investigated the role of anti-inflammatory agents in reducing cardiovascular events. Trehalose is a natural disaccharide able to reduce inflammation by enhancing macrophage autophagic activity. This action has been demonstrated to attenuate atherosclerotic plaque development in various pro-atherogenic animal models.

Wavelength and pulse energy optimization for detecting hypoxia in photoacoustic imaging of the neonatal brain: a simulation study.

Cerebral hypoxia is a severe injury caused by oxygen deprivation to the brain. Hypoxia in the neonatal period increases the risk for the development of neurological disorders, including hypoxic-ischemic encephalopathy, cerebral palsy, periventricular leukomalacia, and hydrocephalus. It is crucial to recognize hypoxia as soon as possible because early intervention improves outcomes.

Optical neural stimulation using the thermoplasmonic effect of gold nano-hexagon.

The use of nanoparticle photothermal effect as adjuvants in neuromodulation has recently received much attention, with many open questions about new nanostructures' effect on the action potential. The photothermal properties of hexagonal gold nanoparticles are investigated in this work, including the absorption peak wavelength and light-heat conversion rate, using both experimental and simulation methods. Furthermore, the ability to use these nanostructures in axonal neural stimulation and cardiac stimulation by measuring temperature changes of gold nano-hexagons under 532 nm laser irradiation is studied.

Improving vascular imaging with co-planar mutually guided photoacoustic and diffuse optical tomography: a simulation study.

Diffuse optical tomography (DOT) and photoacoustic tomography (PAT) are functional imaging modalities that provide absorption coefficient maps of the tissue. Spatial resolution of DOT is relatively low due to light scattering characteristics of the tissue. On the other hand, although PAT can resolve regions of different absorptions with a high spatial resolution, measuring the absolute value of optical absorptions using PAT is challenging due to unknown light fluence distribution in the tissue.

In vivo detection of human cutaneous beta-carotene using computational optical clearing.

The content of dermal beta-carotene can be a good indicator showing the body health. Because, it is involved in production of vitamin A maintaining healthy skin and mucous membranes. Also, it reduces the risk of cardiovascular diseases and its antioxidant capacity prevents the formation of cancerous cells.

The Temporal Confounding Effects of Extra-cerebral Contamination Factors on the Hemodynamic Signal Measured by Functional Near-Infrared Spectroscopy.

Functional near-infrared spectroscopy (fNIRS) has been broadly applied for optical brain imaging. This method is hemodynamic-based functional brain imaging relying on the measurement of the neurovascular coupling to detect changes in cerebral neuronal activities. The extra-cerebral hemodynamic changes are important contaminating factors in fNIRS measurements.

Blind Localization of Heating in Neural Tissues Induced by a Train of the Infrared Pulse Laser.

Recently, infrared lasers (wavelengths larger than 1100 nm) have been applied to stimulate neural tissues. Infrared neural stimulation (INS) has some advantages over conventional electric stimulation, including contact-free delivery, spatial precision, and lack of stimulation artifacts. In this study and based on a photothermal mechanism, we applied the heat diffusion equation to study temperature variation of a biological phantom during INS.

Head model based on the shape of the subject's head for optical brain imaging.

Optical imaging methods such as near-infrared spectroscopy and diffuse optical tomography rely on models to solve the inverse problem. Imaging an adult human head also requires a head model. Using a model, which makes describing the structure of the head better, leads to acquiring a more accurate absorption map.

Influence of radiant exposure and repetition rate in infrared neural stimulation with near-infrared lasers.

In this study, we combine heat diffusion equation and modified Hodgkin-Huxley axonal model to investigate how an action potential is generated during infrared neural stimulation. The effects of temporal and spatial distribution of heat induced by infrared pulsed lasers on variation of electrical membrane capacitance are investigated. These variations can lead to depolarize the membrane and generate an action potential.

Correction: Maternal separation blunted spatial memory formation independent of peripheral and hippocampal insulin content in young adult male rats.

[This corrects the article DOI: 10.1371/journal.pone.

Maternal separation blunted spatial memory formation independent of peripheral and hippocampal insulin content in young adult male rats.

This study explores the effects of maternal separation as a chronic early life stress (ELS) on pancreatic islets insulin content and secretion, and their potential relationship with the hippocampus insulin content and spatial memory in young adulthood. Male rat offspring were divided into two groups: stress (STR) and non-stress (non-STR) groups. The animals of the STR group were separated from their mothers during postnatal days (PND) 1 to 21.

Is echocardiographic epicardial fat thickness increased in patients with coronary artery disease? A systematic review and meta-analysis.

Background: The relation of epicardial fat thickness (EFT) to coronary artery disease (CAD) has recently been reported in multiple studies. Echocardiography is a safe and relatively inexpensive and accessible approach to assess regional EFT, which can be performed easily in many centers.

Objective: To determine the association between echocardiographic EFT and the presence or the absence of CAD.

Successful treatment of prosthetic pulmonary valve thrombosis with reteplase: a case report.

Pulmonary prosthetic valve thrombosis is a serious and rare complication with high mortality. Using reteplase for treatment of prosthesis thrombosis is rarely reported. We report the first case in Iran of a thrombosed pulmonary valve in a patient who had undergone repair of tetralogy of Fallot, which was successfully treated twice with intravenous thrombolytic therapy with reteplase.

Combination of analytical and experimental optical clearing of rodent specimen for detecting beta-carotene: phantom study.

Recently, compression optical clearing (OC) was applied to detect dermal carotenoid using reflection spectroscopy. To enhance the precision and accuracy of reflection spectroscopy to better detect the spectral absorption of beta-carotene inside biological phantom, here, we simultaneously use compression and immersion OC using dimethyl sulfoxide. In addition, we analytically extract the absorption coefficient of beta-carotene using diffuse reflectance spectroscopy (as an analytical OC).

Factors Affecting In-stent Restenosis in Patients Undergoing Percutaneous Coronary Angioplasty.

Percutaneous coronary angioplasty (PCI) and stent implantation are the most common therapeutic strategies for coronary artery stenosis; however, in-stent restenosis (ISR) is one of its important challenges. Although in some studies, coronary artery disease (CAD) factors are deemed to be the causes of ISR, in some others, the relationship between CAD factors and ISR are not observed. Over the past ten years, there has been no review article on factors affecting the ISR.

Development of low-cost photoacoustic imaging systems using very low-energy pulsed laser diodes.

With the growing application of photoacoustic imaging (PAI) in medical fields, there is a need to make them more compact, portable, and affordable. Therefore, we designed very low-cost PAI systems by replacing the expensive and sophisticated laser with a very low-energy laser diode. We implemented photoacoustic (PA) microscopy, both reflection and transmission modes, as well as PA computed tomography systems.

Diffuse optical tomography: image reconstruction and verification.

Introduction: In this study, we intend to use diffuse optical Tomography (DOT) as a noninvasive, safe and low cost technique that can be considered as a functional imaging method and mention the importance of image reconstruction in accuracy and procession of image. One of the most important and fastest methods in image reconstruction is the boundary element method (BEM). This method is introduced and employed in our works.

Mechanisms of Laser-Tissue Interaction: II. Tissue Thermal Properties.

Laser-tissue interaction is of great interest due to its significant application in biomedical optics in both diagnostic and treatment purposes. Major aspects of the laser-tissue interaction which has to be considered in biomedical studies are the thermal properties of the tissue and the thermal changes caused by the interaction of light and tissue. In this review paper the effects of light on the tissue at different temperatures are discussed.

Study of the effect of mechanical pressure on determination of position and size of tumor in biological phantoms.

Diffuse optical tomography (DOT) is an emerging oncological imaging modality that is based on a near-infrared optical technique. DOT provides the spatial volume and depth of tumors by determination of optical properties of biological tissues, such as the absorption and scattering coefficients. During a DOT, the optical fibers are kept in contact with biological tissues that introduce a certain amount of pressure on the local biological tissue.

Study of short-pulse laser propagation in biological tissue by means of the boundary element method.

Propagation of short pulses of light through biological tissues can be studied by numerically solving the diffusion equation. The boundary integral method was used to convert the differential equation to integral form and the result was solved using the boundary element method. The effects of different optical parameters of the tissue, i.

Boundary integral method for simulating laser short-pulse penetration into biological tissues.

The study of short-pulse propagation through biological tissues is important due to the medical applications of short-pulse lasers. Techniques used for numerical study of short pulses through human tissues include the Monte Carlo (MC) method, the finite-element method, and the finite-difference time-domain (FDTD), but these are often time consuming. Recently, the boundary integral method (BIM) was applied to overcome this problem.