Biology subjects

Qureshi, M. M.

Publications and source records attributed to Qureshi, M. M..

4 recordsLinked to original sources

bioRxiv2023

Photobiomodulation Therapy for a Novel Olfactory Dysfunction Ischemic Stroke Model

A.BackgroundIschemic stroke typically accompanies numerous disorders ranging from somatosensory dysfunction to cognitive impairments, inflicting its patients with various neurologic symptoms. Among pathologic outcomes, post-stroke olfactory dysfunction is frequently observed. Despite the well-known prevalence, therapy options for such compromised olfaction are limited, likely due to the complexity of the olfactory bulb architecture, which encompasses both the peripheral and central nervous systems. As photobiomodulation (PBM) emerged for treating stroke-associated symptoms, the effectiveness of PBM on the stroke-induced impairment of the olfactory function was explored. PurposeTo address the efficacy of PBM therapy on the olfactory bulb damage caused by ischemic stroke using both behavioral and histologic and inflammatory markers in the newly developed stroke mouse models. MethodsNovel mouse models with olfactory dysfunction were prepared using photothrombosis (PT) in the olfactory bulb on day 0. Moreover, post-PT PBM was performed daily from day 2 to day 7 by irradiating the olfactory bulb using an 808 nm laser with the fluence of 40 J/cm2 (325 mW/cm2 for 2 minutes per day). The buried food test (BFT) was used for scoring behavioral acuity in the food-deprived mice to assess the olfactory function before PT, after PT, and after PBM. Histopathological examinations and cytokine assays were performed on the mouse brains harvested on day 8. ResultsThe results from BFT were specific to the individual, with positive correlations between the baseline latency time measured before PT and alterations at the ensuing stages for both the PT and PT+PBM groups. Also in both groups, the correlation analysis showed a significant positive relationship between the early and late latency time changes independent of PBM, implicating a common recovery mechanism. In particular, the PBM treatment largely accelerated the recovery of impaired olfaction after PT with the suppression of inflammatory cytokines while enhancing both the glial and vascular factors (e.g., GFAP, IBA-1, and CD31). ConclusionsThe PBM therapy during the acute phase of ischemia improves the compromised olfactory function by modulating the microenvuronment and tissue inflammation.

neuroscience↗

bioRxiv2022

Differentiation of semi-transparent tissue phantom inclusions using optical coherence tomography towards label-free neurography and lymphography

SignificanceLymphatic and peripheral nervous system imaging is of prime importance for monitoring various important pathologic processes including cancer development, metastasis, and response to therapy. AimOptical coherence tomography (OCT) is a promising approach for this imaging task but is challenged by the near-transparent nature of these structures. Our aim is to detect and differentiate semi-transparent materials using OCT texture analysis, towards label-free neurography and lymphography. ApproachWe have recently demonstrated a novel OCT texture analysis-based approach that used speckle statistics to image lymphatics and nerves in-vivo that does not rely on negative contrast. However, these two near-transparent structures could not be differentiated from each other easily in the texture analysis parameter space. Here we perform a rigorous follow-up study to improve upon this differentiation in controlled phantoms mimicking the optical properties of these tissues. ResultsThe results of the three-parameter Rayleigh distribution fit to the OCT images of six types of tissue-mimicking materials varying in transparency and biophysical properties demonstrate clear differences between them, suggesting routes for improved lymphatics-nerves differentiation. ConclusionsWe demonstrate a novel OCT texture analysis based lymphatics-nerves differentiation methodology in tissue-simulating phantoms. Future work will focus on in-vivo lymphangiography and neurography studies of longitudinal treatment monitoring for therapy feedback and optimization.

cancer biology↗

bioRxiv2021

Fast volumetric imaging with line-scan confocal microscopy by an electro-tunable lens

In microscopic imaging of biological tissues, particularly real-time visualization of neuronal activities, rapid acquisition of volumetric images poses a prominent challenge. Typically, two-dimensional (2D) microscopy can be devised into an imaging system with 3D capability using any varifocal lens. Despite the conceptual simplicity, such an upgrade yet requires additional, complicated device components and suffers a reduced acquisition rate, which is critical to document neuronal dynamics properly. In this study, we implemented an electro-tunable lens (ETL) in the line-scan confocal microscopy, enabling the volumetric acquisition at the rate of 20 frames per second with the maximum volume of interest of 315 x 315 x 80 m3. The axial extent of point-spread-function (PSF) was 17.6 {+/-} 1.6 m and 90.4 {+/-} 2.1 m with the ETL operating in either stationary or resonant mode, respectively, revealing significant depth elongation by the resonant mode ETL microscopy. We further demonstrated the utilities of the ETL system by volume imaging of cleared mouse brain ex vivo samples and in vivo brains. The current study foregrounds the successful application of resonant ETL for constructing a basis for a high-performance 3D line-scan confocal microscopy system, which will enhance our understanding of various dynamic biological processes.

bioengineering↗

bioRxiv2021

Quantitative blood flow estimation in vivo by optical speckle image velocimetry

Speckle based methods are popular non-invasive, label-free full-field optical techniques for imaging blood flow maps at single vessel resolution with a high temporal resolution. However, conventional speckle approach cannot provide an absolute velocity map with magnitude and direction. Here, we report a novel optical speckle image velocimetry (OSIV) technique for measuring the quantitative blood flow vector map by utilizing particle image velocimetry with speckle cross-correlations. We demonstrate that our OSIV instrument has a linearity range up to 7 mm/s, higher than conventional optical methods. Our method can measure the absolute flow vector map at up to 190 Hz without sacrificing the image size, and it eliminates the need for a high-speed camera/detector. We applied OSIV to image the blood flow in a mouse brain, and as a proof of concept, imaged the real-time dynamic changes in the cortical blood flow field during the stroke process in vivo. Our wide-field quantitative flow measurement OSIV method without the need of tracers provides a valuable tool for studying the healthy and diseased brain.

biophysics↗