1. Articles from gracie vargas

    1-7 of 7
    1. Scattering Angle Resolved Optical Coherence Tomography Detects Early Changes in 3xTg Alzheimer's Disease Mouse Model

      Scattering Angle Resolved Optical Coherence Tomography Detects Early Changes in 3xTg Alzheimer's Disease Mouse Model

      Purpose : Clinical intensity-based optical coherence tomographic retinal imaging is unable to resolve some of the earliest changes to Alzheimer's disease (AD) neurons. The aim of this pilot study was to demonstrate that scattering-angle-resolved optical coherence tomography (SAR - OCT), which is sensitive to changes in light scattering angle, is a candidate retinal imaging modality for early AD detection. SAR-OCT signal data may be sensitive to changes in intracellular constituent morphology that are not detectable with conventional OCT. Methods : In this cross-sectional study, retinas of a triple transgenic mouse model of AD (3xTg-AD) were imaged alongside age-matched control mice (C57BL/6J ...

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    2. Image-based noninvasive evaluation of colorectal mucosal injury in sheep after topical application of microbicides

      Image-based noninvasive evaluation of colorectal mucosal injury in sheep after topical application of microbicides

      Background: Successful development of topical rectal microbicides requires preclinical evaluation in suitable large animal models. Our previous studies have demonstrated the benefits of high-resolution optical coherence tomography (OCT) to visualize subclinical microbicide toxicity in the sheep vagina. In the current study, we evaluated the potential application of colonoscopy and OCT to visualize and quantify the effects of topical products on sheep colorectal tissue, as assessed by advanced imaging techniques. Methods: Yearling virginal female sheep were treated rectally with a single 8-mL dose of 0.2% benzalkonium chloride (BZK) solution or phosphate-buffered saline control. Imaging was performed before and 30 minutes ...

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    3. Optical coherence tomography for assessment of microbicide safety in a small animal model

      Optical coherence tomography for assessment of microbicide safety in a small animal model

      Sensitive imaging techniques for small animals are needed to assess drug toxicity in preclinical studies. Optical coherence tomography (OCT) provides a noninvasive tool for high-resolution, depth-resolved visualization of drug-induced changes in tissue morphology. In a mouse model, we utilize OCT to assess vaginal tissue integrity following the application of topical microbicides (drugs used to prevent infection). Mice are challenged with herpes simplex virus-2 (HSV-2) to determine the correlation of tissue damage as quantified by OCT to increased susceptibility. The microbicide benzalkonium chloride (BZK) (0.02, 0.2, or 2%) or phosphate buffered saline control is administered intravaginally. In vivo OCT ...

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    4. Monitoring Vaginal Epithelial Thickness Changes Noninvasively in Sheep Using Optical Coherence Tomography

      Monitoring Vaginal Epithelial Thickness Changes Noninvasively in Sheep Using Optical Coherence Tomography

      Objective High-resolution optical coherence tomography (OCT), can be used noninvasively to evaluate vaginal morphologic features, including epithelial thickness, to assess this protective barrier in transmission of sexually transmitted infections and to monitor tissue response to topical medications and hormonal fluctuations. We examined the utility of OCT to measure epithelial thickness noninvasively before and after topical treatment with a drug that causes epithelial thinning. Study Design Twelve female sheep were treated with intravaginal placebo (n=4) or nonoxynol-9 (n=8). Vaginal OCT images were obtained before and 24 hours after treatment. Four sheep in the nonoxynol-9 group were also examined on ...

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    5. Automated segmentation algorithm for detection of changes in vaginal epithelial morphology using optical coherence tomography

      Automated segmentation algorithm for detection of changes in vaginal epithelial morphology using optical coherence tomography

      We have explored the use of optical coherence tomography (OCT) as a noninvasive tool for assessing the toxicity of topical microbicides, products used to prevent HIV, by monitoring the integrity of the vaginal epithelium. A novel feature-based segmentation algorithm using a nearest-neighbor classifier was developed to monitor changes in the morphology of vaginal epithelium. The two-step automated algorithm yielded OCT images with a clearly defined epithelial layer, enabling differentiation of normal and damaged tissue. The algorithm was robust in that it was able to discriminate the epithelial layer from underlying stroma as well as residual microbicide product on the surface ...

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    6. High Resolution Imaging of Epithelial Injury in the Sheep Cervicovaginal Tract: A Promising Model for Testing Safety of Candidate Microbicides

      Abstract: Background: Access to readily available large animal models and sensitive noninvasive techniques that can be used for the evaluation of microbicide-induced changes in tissue could significantly facilitate preclinical evaluations of microbicide safety. The sheep cervicovaginal tract, with stratified squamous epithelium similar to humans, holds promise as a large animal model used before nonhuman primates. In addition, optical coherence tomography (OCT) could enable high resolution visualization of tissue morphology and noninvasive assessment of microbicide-induced epithelial injury. Methods: We evaluated the dose response of sheep cervicovaginal tract to benzalkonium chloride (BZK). Twenty sheep received treatment with phosphate-buffered saline or BZK solution ...
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    7. Laser treatment of cutaneous vascular lesions

      Methods for treating maladies such as cutaneous vascular lesions. A patient in need of vascular lesion treatment is identified. A hyperosmotic agent is administered to a region adjacent the lesion. Blood flow velocity is slowed within the region using the hyperosmotic agent, and the lesion is exposed to laser radiation.
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    1-7 of 7
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    Automated segmentation algorithm for detection of changes in vaginal epithelial morphology using optical coherence tomography Monitoring Vaginal Epithelial Thickness Changes Noninvasively in Sheep Using Optical Coherence Tomography Optical coherence tomography for assessment of microbicide safety in a small animal model Image-based noninvasive evaluation of colorectal mucosal injury in sheep after topical application of microbicides Scattering Angle Resolved Optical Coherence Tomography Detects Early Changes in 3xTg Alzheimer's Disease Mouse Model A novel algorithm for multiplicative speckle noise reduction in ex vivo human brain OCT images Volumetric characterization of microvasculature in ex vivo human brain samples by serial sectioning optical coherence tomography Depth of focus extension in optical coherence tomography using ultrahigh chromatic dispersion of zinc selenide Retinal changes in bipolar disorder as an endophenotype candidate: Comparison of OCT-detected retinal changes in patients, siblings, and healthy controls Intraoperative optical coherence tomography guided 25G micro-amount trajectory vitrectomy for the treatment of penetrating ocular injury caused by a foreign body in the right eye: A case study Optical coherence tomography angiography reveals paradoxically decreasing choroidal thickness & increasing blood flow in remitting Vogt Koyanagi Harada syndrome A comparison of macular ganglion cell and retinal nerve fibre layer optical coherence tomographic parameters as predictors of visual outcomes of surgery for pituitary tumours