scholarly journals Fundus Autofluorescence and Clinical Applications

2021 ◽  
Author(s):  
Cameron Pole ◽  
Hossein Ameri
Keyword(s):  
Structural Changes ◽  
Clinical Evidence ◽  
Imaging Techniques ◽  
Incident Light ◽  
Fundus Autofluorescence ◽  
Clinical Applications ◽  
Retinal Degenerations ◽  
Clinical Scenarios ◽  
Before And After

Fundus autofluorescence (FAF) has allowed in vivo mapping of retinal metabolic derangements and structural changes not possible with conventional color imaging. Incident light is absorbed by molecules in the fundus, which are excited and in turn emit photons of specific wavelengths that are captured and processed by a sensor to create a metabolic map of the fundus. Studies on the growing number of FAF platforms has shown each may be suited to certain clinical scenarios. Scanning laser ophthalmoscopes, fundus cameras, and modifications of these each have benefits and drawbacks that must be considered before and after imaging to properly interpret the images. Emerging clinical evidence has demonstrated the usefulness of FAF in diagnosis and management of an increasing number of chorioretinal conditions, such as agerelated macular degeneration, central serous chorioretinopathy, retinal drug toxicities, and inherited retinal degenerations such as retinitis pigmentosa and Stargardt disease. This article reviews commercial imaging platforms, imaging techniques, and clinical applications of FAF.

scholarly journals Decrease in Platelet Aggregability after Total Oophorectomy

1977 ◽  
Author(s):  
H. Yamazaki ◽  
T. Motomiya ◽  
M. Sonoda ◽  
N. Miyagawa
Keyword(s):  
Platelet Count ◽  
Clinical Evidence ◽  
Coulter Counter ◽  
Control Group ◽  
Bilateral Oophorectomy ◽  
Platelet Volume ◽  
Platelet Aggregability ◽  
Significant Difference ◽  
Before And After

Substantial clinical evidence indicates that large doses of estrogen frequenly result in thromboembolic disorders. Effects of estrogen on platelet aggregability were examined in women with uterine myoma before and after oophorectomy. Bilateral oophorectomy on 15 cases (48.7+0.12 yrs, mean+SE) and unilateral or no oophorectomy on 18 cases (control group : 42.2+0.18 yrs) were performed with myomectomy of the uterus. On one day before and one day, one week and one month after the operation performed, their platelet count by Coulter counter, platelet volume by Coulter channelyzer and platelet aggregability by Sienco aggregometer were measured. 24 hrs total estrogen in urine was also determined. In the control group, platelet counts were 85.1+ 4.9 % of the preoperated value one day after, 127.9+9.0 % one week after and 98.1+7.6 % one month after the operation. In the bilateral oophorectomy group, these were 82.4+5.2 % one day after, 124.0+4.7 % one week after and 96.1+4.8 % one month after. Both the groups showed the same change. Platelet aggregability by 3 μM ADP were 76.9+14.3 % one day after, 203.0+57.1 % one week after and 193.4+59.0 % one month after in the control, while 55.0+13.6 % one day after, 102.5+12.9 % one week after and 60.6+14.7 % one month after the operation in the total oophorectomy group. There was a statistically significant difference in the values obtained one month after the operation between the groups (p<0.05). Characteristic changes in platelet volumes were also observed. A significant correlation was observed between the platelet aggre-gabilities and the daily urinary estrogen excretion levels. The above results suggest that estrogen may enhance platelet aggregability in vivo.

scholarly journals Plasticity after cortical stroke involves potentiating responses of pre-existing circuits but not functional remapping to new circuits

2020 ◽  
Author(s):  
William A Zeiger ◽  
Máté Marosi ◽  
Satvir Saggi ◽  
Natalie Noble ◽  
Isa Samad ◽  
...  
Keyword(s):  
Animal Studies ◽  
Structural Changes ◽  
Recovery Of Function ◽  
Definitive Evidence ◽  
Before And After ◽  
Maladaptive Plasticity ◽  
Adaptive Circuit ◽  
Evoked Activity ◽  
Sensory Evoked

AbstractFunctional recovery after stroke is thought to be mediated by adaptive circuit plasticity, whereby surviving neurons assume the roles of those that died. This “remapping” hypothesis is based on human brain mapping studies showing apparent reorganization of cortical sensorimotor maps and animal studies documenting molecular and structural changes that could support circuit rewiring. However, definitive evidence of remapping is lacking, and other studies have suggested that maladaptive plasticity mechanisms, such as enhanced inhibition in peri-infarct cortex, might actually limit plasticity after stroke. Here we sought to directly test whether neurons can change their response selectivity after a stroke that destroys a single barrel (C1) within mouse primary somatosensory cortex. Using multimodal in vivo imaging approaches, including two-photon calcium imaging to longitudinally record sensory-evoked activity in peri-infarct cortex before and after stroke, we found no evidence to support the remapping hypothesis. In an attempt to promote plasticity via rehabilitation, we also tested the effects of forced use therapy by plucking all whiskers except the C1 whisker. Again, we failed to detect an increase in the number of C1 whisker-responsive neurons in surrounding barrels even 2 months after stroke. Instead, we found that forced use therapy potentiated sensory-evoked responses in a pool of surviving neurons that were already C1 whisker responsive by significantly increasing the reliability of their responses. Together, our results argue against the long-held theory of functional remapping after stroke, but support a plausible circuit-based mechanism for how rehabilitation may improve recovery of function.

scholarly journals Raman Imaging and Chemometrics Evaluation of Natural and Synthetic Beeswaxes as Matrices for Nanostructured Lipid Carriers Development

2021 ◽  
Vol 8 (32) ◽  
Author(s):  
Hery Mitsutake ◽  
Gustavo da Silva ◽  
Lígia Ribeiro ◽  
Eneida de Paula ◽  
Ronei Poppi ◽  
...  
Keyword(s):  
Structural Changes ◽  
Imaging Techniques ◽  
Nanostructured Lipid Carriers ◽  
Multivariate Curve Resolution ◽  
Initial Time ◽  
Pharmaceutical Development ◽  
Before And After ◽  
Copaiba Oil ◽  
Components Analysis ◽  
Changes Over Time

Beeswaxes are interesting solid lipids for the development of nanostructured lipid carriers (NLC), and their origin can be either natural or synthetic. Due to this difference, their performance should be distinct and unstable formulations can be generated. The objective of this work was to investigate miscibility and structural changes (polymorphism) in pre-formulations (blends of solid and liquid lipids) using synthetic and natural beeswaxes in combination with copaiba oil (a natural liquid lipid), in the concentration range of 5.0 to 50.0% (w/w). Raman spectra were acquired over a region of 4 mm2 (mapping mode), dead pixels were removed using Independent Components Analysis (ICA) and Multivariate Curve Resolution – Alternating Least Squares (MCR-ALS) was then used to generate the images. Samples were analyzed at the initial time and after 3 months, using the Distributional Homogeneity Index (DHI) and standard deviation of the histograms. The pre-formulation containing synthetic beeswax showed different structural forms before and after melting, and structural changes over time, depending on the amount of the liquid lipid incorporated. These results demonstrate how spectroscopic imaging techniques can be valuable in pharmaceutical development, as well as the importance of choosing the type and proportion of solid lipid to achieve stable NLC formulations.

scholarly journals Melatonin as a Reducer of Neuro- and Vasculotoxic Oxidative Stress Induced by Homocysteine

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1178
Author(s):  
Kamil Karolczak ◽  
Cezary Watala
Keyword(s):  
Oxidative Stress ◽  
Structural Changes ◽  
Clinical Evidence ◽  
Neuronal Degeneration ◽  
Antioxidant Properties ◽  
In Vitro Models ◽  
In Vivo Models ◽  
Initial Research

The antioxidant properties of melatonin can be successfully used to reduce the effects of oxidative stress caused by homocysteine. The beneficial actions of melatonin are mainly due to its ability to inhibit the generation of the hydroxyl radical during the oxidation of homocysteine. Melatonin protects endothelial cells, neurons, and glia against the action of oxygen radicals generated by homocysteine and prevents the structural changes in cells that lead to impaired contractility of blood vessels and neuronal degeneration. It can be, therefore, assumed that the results obtained in experiments performed mainly in the in vitro models and occasionally in animal models may clear the way to clinical applications of melatonin in patients with hyperhomocysteinemia, who exhibit a higher risk of developing neurodegenerative diseases (e.g., Parkinson’s disease or Alzheimer’s disease) and cardiovascular diseases of atherothrombotic etiology. However, the results that have been obtained so far are scarce and have seldom been performed on advanced in vivo models. All findings predominately originate from the use of in vitro models and the scarcity of clinical evidence is huge. Thus, this mini-review should be considered as a summary of the outcomes of the initial research in the field concerning the use of melatonin as a possibly efficient attenuator of oxidative stress induced by homocysteine.

scholarly journals Bone Toolbox: Biomarkers, Imaging Tools, Biomechanics, and Histomorphometry

2018 ◽  
Vol 46 (5) ◽  
pp. 511-529 ◽  
Author(s):  
Aurore Varela ◽  
Jacquelin Jolette
Keyword(s):  
Computed Tomography ◽  
Bone Histomorphometry ◽  
Structural Changes ◽  
Imaging Techniques ◽  
Quantitative Computed Tomography ◽  
Biomechanical Testing ◽  
Drug Effects ◽  
Imaging Modalities ◽  
Micro Computed Tomography

Bone is a unique tissue with turnover, metabolic, and cellular activities that vary through development to aging and with a mineralized matrix in which the current state and the history of a bone coexist. Qualitative histopathology often lacks sensitivity to detect changes in bone formation, mineralization and resorption, which often requires chronic dosing to result in structural changes such as variation in bone mass and geometry. A large panel of modalities can be used to fully analyze the health of the skeleton, including biomarker evaluation in serum or urine, imaging techniques ranging from radiology to computed tomography, biomechanical testing, and undecalcified tissue processing with bone histomorphometry. The use of clinically relevant biomarkers provides an important noninvasive, sensitive, rapid, and real-time tool to monitor bone activity at the whole skeleton level when conducting safety assessments in a preclinical setting. Imaging modalities also allow in vivo longitudinal assessments with a powerful, noninvasive and clinically translatable tools to monitor drug effects. Different imaging modalities are used in the preclinical studies to evaluate the bone tissues: standard radiography, dual-energy X-ray absorptiometry, peripheral quantitative computed tomography (pQCT), micro-computed tomography, and high-resolution pQCT. Bone histomorphometry is an important tool that provides sensitive evaluation to detect effects of test articles on bone resorption, formation, mineralization, remodeling rates and growth to address a potential target- or class-related theoretical bone liability. Ultimately, the measurement of bone mechanical properties in pharmaceutical testing is critical to understand the potential effects of that pharmaceutical on bone health and fracture risk. Important considerations are required for including these different techniques in toxicology rodents and nonrodent studies, to actually integrate these into safety assessment.

scholarly journals Foreword

2002 ◽  
Vol 1 (6) ◽  
pp. 417-417
Author(s):  
Orhan Nalcioglu ◽  
Laurence Clarke
Keyword(s):  
Medical Imaging ◽  
Imaging Techniques ◽  
Small Animal ◽  
Spatial Localization ◽  
Clinical Applications ◽  
Special Issue ◽  
Clinical Investigations ◽  
Measurement Tools ◽  
Important Measurement

In vivo medical imaging has become one of the most important measurement tools in biomedical research and clinical investigations. Medical imaging applications cover a broad spectrum going from small animal research to human studies. This is due to the fact that in vivo medical imaging techniques based on various modalities are capable of providing anatomic, functional, and metabolic information non-invasively with accurate spatial localization enabling longitudinal studies on the same subject. One of the most significant application of such techniques has been in the study of cancer. In this special issue on in vivo medical imaging, we tried to give the readers a flavor of the types of studies that are being done in cancer research and clinical applications. We should emphasize that the topics covered here due to limited space will only provide the readers with a rather limited view. Furthermore, one of the new and upcoming imaging techniques, namely molecular imaging will not be covered here since there have been various extensive reviews of the field have been given in the literature.

scholarly journals Functional Imaging of the Ocular Fundus Using an 8-Band Retinal Multispectral Imaging System

Instruments ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 12
Author(s):  
Emanuel R. de Carvalho ◽  
Richelle J. M. Hoveling ◽  
Cornelis J. F. van Noorden ◽  
Reinier O. Schlingemann ◽  
Maurice C. G. Aalders
Keyword(s):  
Oxygen Saturation ◽  
Functional Imaging ◽  
Multispectral Imaging ◽  
Imaging System ◽  
Imaging Techniques ◽  
Incident Light ◽  
Contrast Imaging ◽  
Blood Oxygen Saturation ◽  
Full Scan

Application of functional imaging in ophthalmology requires efficient imaging techniques that can detect and quantify chromophores to visualise processes in vivo. The aim of the present study was to develop and evaluate a fast and affordable imaging system. We describe an eight-band retinal multispectral imaging (MSI) system and compare it with a hyperspectral imaging (HSI) device. Determination of blood oxygen saturation was studied as proof of principle. Reflectance of incident light is measured as 1/absorbance at different wavelengths between 440 nm and 580 nm. Both devices have incorporated optical bandpass filters in a mydriatic fundus camera. The MSI system scans the retina at eight pre-defined wavelengths specific for the spectrum of haemoglobin. The HSI system acquires a full scan from 480 to 720 nm in 5 nm steps. A simple assessment of the ratio between the absorbance peaks of oxygenated haemoglobin (HbO2) and reduced haemoglobin (HbR) was not suitable for generating validated oxygenation maps of the retina. However, a correction algorithm that compares the measured reflectance with reflectance spectra of fully oxygenated and fully deoxygenated blood allowed our MSI setup to estimate relative oxygen saturation at higher levels, but underestimated relative oxygen saturation at lower levels. The MSI device generated better quality images than the HSI device. It allows customisation with filter sets optimised for other chromophores of interest, and augmented with extrinsic contrast imaging agents, it has the potential for a wider range of ophthalmic molecular imaging applications.

27. Low Frequency Ultrasound Imaging of Apoptosis in Tumor Response: Non-Invasive Monitoring of Chemotherapy Effects

2018 ◽  
Author(s):  
Stephanie Zhou
Keyword(s):  
Cell Death ◽  
Ultrasound Imaging ◽  
Structural Changes ◽  
Imaging Techniques ◽  
Low Frequency ◽  
Acoustic Properties ◽  
High Frequency Ultrasound ◽  
Noninvasive Methods ◽  
Frequency Ultrasound

Due to the growing costs of chemotherapy, previous imaging techniques such as MRI or CT scans have become too time-consuming in the assessment of chemotherapy’s effects. With results generated about 2 weeks later, the patient is exposed to the negative side effects of these medications with the possibility that chemotherapy may not be improving their prognosis. Thus, ultrasound has become increasingly popular as a method to determine chemotherapy’s effect on tumors within 24 hours. Both low and high-frequency ultrasound are novel, noninvasive methods for detecting cell death based on changes in cell morphology. Condensation, fragmentation and alterations in the cell nucleus during apoptosis are linked to changes in the cell’s acoustic properties, as indicated by experimental evidence. In this study, quantitative ultrasound was used to follow responses of tumor models to chemotherapy in vivo. As studies have shown that structural changes can occur as early as 24 hours after treatment, ultrasound imaging was administered before and 24 hours after treatment. Changes in ultrasound parameters such as spectral slope, Y-intercept, and midband fit were analyzed relative to pretreatment control data and when compared to changes in the tumors seen through cell staining, changes consistent with cell death were observed.

scholarly journals Diagnosis and Management of Iridocorneal Endothelial Syndrome

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Marta Sacchetti ◽  
Flavio Mantelli ◽  
Marco Marenco ◽  
Ilaria Macchi ◽  
Oriella Ambrosio ◽  
...  
Keyword(s):  
Anterior Chamber ◽  
Corneal Endothelium ◽  
Structural Changes ◽  
Imaging Techniques ◽  
Corneal Edema ◽  
Secondary Glaucoma ◽  
Anterior Chamber Angle ◽  
Chamber Angle ◽  
Iris Atrophy

The iridocorneal endothelial (ICE) syndrome is a rare ocular disorder that includes a group of conditions characterized by structural and proliferative abnormalities of the corneal endothelium, the anterior chamber angle, and the iris. Common clinical features include corneal edema, secondary glaucoma, iris atrophy, and pupillary anomalies, ranging from distortion to polycoria. The main subtypes of this syndrome are the progressive iris atrophy, the Cogan-Reese syndrome, and the Chandler syndrome. ICE syndrome is usually diagnosed in women in the adult age. Clinical history and complete eye examination including tonometry and gonioscopy are necessary to reach a diagnosis. Imaging techniques, such as in vivo confocal microscopy and ultrasound biomicroscopy, are used to confirm the diagnosis by revealing the presence of “ICE-cells” on the corneal endothelium and the structural changes of the anterior chamber angle. An early diagnosis is helpful to better manage the most challenging complications such as secondary glaucoma and corneal edema. Treatment of ICE-related glaucoma often requires glaucoma filtering surgery with antifibrotic agents and the use of glaucoma drainage implants should be considered early in the management of these patients. Visual impairment and pain associated with corneal edema can be successfully managed with endothelial keratoplasty.

scholarly journals Application of In Vivo Imaging Techniques for Monitoring Natural Killer Cell Migration and Tumor Infiltration

Cancers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1318 ◽  
Author(s):  
Prakash Gangadaran ◽  
Ramya Lakshmi Rajendran ◽  
Byeong-Cheol Ahn
Keyword(s):  
Molecular Imaging ◽  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
Therapeutic Potential ◽  
Imaging Modality ◽  
Imaging Techniques ◽  
Killer Cell ◽  
Clinical Scenarios

In recent years, the use of natural killer (NK) cell-based immunotherapy has shown promise against various cancer types. To some extent therapeutic potential of NK cell-based immunotherapy depends on migration of NK cells towards tumors in animal models or human subjects and subsequent infiltration. Constant improvement in the pharmacological and therapeutic properties of NK cells is driving the performance and use of NK cell-based immunotherapies. In this review, we summarize the molecular imaging techniques used in monitoring the migration and infiltration of NK cells in vivo at preclinical and clinical levels. A review of pros and cons of each molecular imaging modality is done. Finally, we provide our perception of the usefulness of molecular imaging approaches for in vivo monitoring of NK cells in preclinical and clinical scenarios.

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