scholarly journals Reflective mirror-based line-scan adaptive optics OCT

2021 ◽  
Author(s):  
Vimal Prabhu Pandiyan ◽  
Xiaoyun Jiang ◽  
James A Kuchenbecker ◽  
Ramkumar Sabesan
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Ex Vivo ◽  
Optical Design ◽  
Structure And Function ◽  
Line Scan ◽  
Reflective Mirror ◽  
Retinal Structure ◽  
And Function

Line-scan OCT, incorporated with adaptive optics (AO), offers high resolution, speed and sensitivity for imaging retinal structure and function in vivo. Here, we introduce its implementation with reflective mirror-based afocal telescopes, optimized for imaging light-induced retinal activity (optoretinography) and weak retinal reflections at the cellular scale. A non-planar optical design was followed based on previous recommendations with key differences specific to a line-scan geometry. The three beam paths fundamental to an OCT system -illumination/sample, detection, and reference - were modeled in Zemax optical design software to yield theoretically diffraction-limited performance over a 2.2 deg. field-of-view and 1.5 D vergence range at the eye's pupil. The performance for imaging retinal structure was exemplified by cellular-scale visualization of retinal ganglion cells, macrophages, foveal cones, and rods in human observers. The performance for functional imaging was exemplified by resolving the light-evoked optical changes in foveal cone photoreceptors where the spatial resolution was sufficient for cone spectral classification at an eccentricity 0.3 deg. from the foveal center. This enabled the first in vivo demonstration of reduced S-cone (short-wavelength cone) density in the human foveola, thus far observed only in ex vivo histological preparations. Together, the feasibility for high resolution imaging of retinal structure and function demonstrated here holds significant potential for basic science and translational applications.

scholarly journals Reflective mirror-based line-scan adaptive optics OCT for imaging retinal structure and function

2021 ◽  
Vol 12 (9) ◽  
pp. 5865
Author(s):  
Vimal Prabhu Pandiyan ◽  
Xiaoyun Jiang ◽  
James A. Kuchenbecker ◽  
Ramkumar Sabesan
Keyword(s):  
Adaptive Optics ◽  
Structure And Function ◽  
Line Scan ◽  
Reflective Mirror ◽  
Retinal Structure ◽  
And Function

Adaptive optics line-scan OCT for high-speed imaging of retinal structure and function (Conference Presentation)

2020 ◽  
Author(s):  
Vimal Prabhu Pandiyan ◽  
Aiden M. Bertelli ◽  
James Kuchenbecker ◽  
Kevin C. Boyle ◽  
Tong Ling ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
High Speed ◽  
Structure And Function ◽  
High Speed Imaging ◽  
Line Scan ◽  
Retinal Structure ◽  
And Function

scholarly journals Fast widefield imaging of neuronal structure and function with optical sectioning in vivo

2020 ◽  
Vol 6 (19) ◽  
pp. eaaz3870 ◽  
Author(s):  
Ziwei Li ◽  
Qinrong Zhang ◽  
Shih-Wei Chou ◽  
Zachary Newman ◽  
Raphaël Turcotte ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
In Vivo Imaging ◽  
Neuromuscular Junctions ◽  
Structure And Function ◽  
Structured Illumination ◽  
Neuronal Structure ◽  
Optical Sectioning ◽  
Structured Illumination Microscopy ◽  
And Function

Optical microscopy, owing to its noninvasiveness and subcellular resolution, enables in vivo visualization of neuronal structure and function in the physiological context. Optical-sectioning structured illumination microscopy (OS-SIM) is a widefield fluorescence imaging technique that uses structured illumination patterns to encode in-focus structures and optically sections 3D samples. However, its application to in vivo imaging has been limited. In this study, we optimized OS-SIM for in vivo neural imaging. We modified OS-SIM reconstruction algorithms to improve signal-to-noise ratio and correct motion-induced artifacts in live samples. Incorporating an adaptive optics (AO) module to OS-SIM, we found that correcting sample-induced optical aberrations was essential for achieving accurate structural and functional characterizations in vivo. With AO OS-SIM, we demonstrated fast, high-resolution in vivo imaging with optical sectioning for structural imaging of mouse cortical neurons and zebrafish larval motor neurons, and functional imaging of quantal synaptic transmission at Drosophila larval neuromuscular junctions.

scholarly journals The Role of the 3Rs for Understanding and Modeling the Human Placenta

2021 ◽  
Vol 10 (15) ◽  
pp. 3444
Author(s):  
Joana Costa ◽  
Ruth Mackay ◽  
Sophie-Christine de Aguiar Greca ◽  
Alessandro Corti ◽  
Elisabete Silva ◽  
...  
Keyword(s):  
Human Placenta ◽  
Ex Vivo ◽  
Structure And Function ◽  
Collective Impact ◽  
And Function ◽  
Animal Welfare Legislation ◽  
Made In

Modeling the physiology of the human placenta is still a challenge, despite the great number of scientific advancements made in the field. Animal models cannot fully replicate the structure and function of the human placenta and pose ethical and financial hurdles. In addition, increasingly stricter animal welfare legislation worldwide is incentivizing the use of 3R (reduction, refinement, replacement) practices. What efforts have been made to develop alternative models for the placenta so far? How effective are they? How can we improve them to make them more predictive of human pathophysiology? To address these questions, this review aims at presenting and discussing the current models used to study phenomena at the placenta level: in vivo, ex vivo, in vitro and in silico. We describe the main achievements and opportunities for improvement of each type of model and critically assess their individual and collective impact on the pursuit of predictive studies of the placenta in line with the 3Rs and European legislation.

Osseointegration interface of calcified bone and endosseous implants

1992 ◽  
Vol 50 (2) ◽  
pp. 1096-1097
Author(s):  
K.E. Krizan ◽  
J.E. Laffoon ◽  
M.J. Buckley
Keyword(s):  
Structure And Function ◽  
Titanium Implants ◽  
En Bloc ◽  
Endosseous Implants ◽  
Ultrastructural Studies ◽  
The Past ◽  
Cacodylate Buffer ◽  
One Year ◽  
And Function

With increase use of tissue-integrated prostheses in recent years it is a goal to understand what is happening at the interface between haversion bone and bulk metal. This study uses electron microscopy (EM) techniques to establish parameters for osseointegration (structure and function between bone and nonload-carrying implants) in an animal model. In the past the interface has been evaluated extensively with light microscopy methods. Today researchers are using the EM for ultrastructural studies of the bone tissue and implant responses to an in vivo environment. Under general anesthesia nine adult mongrel dogs received three Brånemark (Nobelpharma) 3.75 × 7 mm titanium implants surgical placed in their left zygomatic arch. After a one year healing period the animals were injected with a routine bone marker (oxytetracycline), euthanized and perfused via aortic cannulation with 3% glutaraldehyde in 0.1M cacodylate buffer pH 7.2. Implants were retrieved en bloc, harvest radiographs made (Fig. 1), and routinely embedded in plastic. Tissue and implants were cut into 300 micron thick wafers, longitudinally to the implant with an Isomet saw and diamond wafering blade [Beuhler] until the center of the implant was reached.

Crystal Structures of Fragments D and Double-D from Fibrinogen and Fibrin

1999 ◽  
Vol 82 (08) ◽  
pp. 271-276 ◽  
Author(s):  
Glen Spraggon ◽  
Stephen Everse ◽  
Russell Doolittle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Crystal Structures ◽  
Structure And Function ◽  
X Ray ◽  
Long Period ◽  
And Function

IntroductionAfter a long period of anticipation,1 the last two years have witnessed the first high-resolution x-ray structures of fragments from fibrinogen and fibrin.2-7 The results confirmed many aspects of fibrinogen structure and function that had previously been inferred from electron microscopy and biochemistry and revealed some unexpected features. Several matters have remained stubbornly unsettled, however, and much more work remains to be done. Here, we review several of the most significant findings that have accompanied the new x-ray structures and discuss some of the problems of the fibrinogen-fibrin conversion that remain unresolved. * Abbreviations: GPR—Gly-Pro-Arg-derivatives; GPRPam—Gly-Pro-Arg-Pro-amide; GHRPam—Gly-His-Arg-Pro-amide

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