Browsing by Author "Castle, Philip E."

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    Is Proflavine Exposure Associated with Disease Progression in Women with Cervical Dysplasia? A Brief Report
    (Wiley, 2018) Pantano, Naitielle; Hunt, Brady; Schwarz, Richard A.; Parra, Sonia; Cherry, Katelin; Possati‐Resende, Júlio César; Longatto‐Filho, Adhemar; Fregnani, José Humberto Tavares Guerreiro; Castle, Philip E.; Schmeler, Kathleen; Richards‐Kortum, Rebecca; Bioengineering
    Proflavine is an acridine dye used with high-resolution microendoscopy for in vivo diagnostic evaluation of cervical epithelial cells. However, there are concerns that even short-term exposure of cervical tissue to dilute proflavine may increase cervical cancer risk. We performed a retrospective analysis of women referred for colposcopy to Barretos Cancer Hospital comparing the risk of cervical disease progression in those whose cervical tissue was (n = 232) or was not exposed (n = 160) to proflavine. Patients in both groups underwent treatment and follow-up based on histopathologic results and per the local standards of care. Progression of disease was evaluated by comparing histopathology from the initial visit to the worst subsequent histopathology result from all follow-up visits. Mean duration of follow-up was 18.7 and 20.1 months for the proflavine-exposed and controls groups, respectively. There were no significant differences in disease progression from normal/CIN1 to CIN2/3 or from any initial diagnosis to invasive cancer between the proflavine exposed and control groups overall. Risks of cervical dysplasia progression observed in this study are in agreement with those of the natural history of cervical cancer. Our results suggest that cervical exposure to dilute proflavine does not increase the risk of cervical precancer and cancer.
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    A low-cost, paper-based hybrid capture assay to detect high-risk HPV DNA for cervical cancer screening in low-resource settings
    (Royal Society of Chemisty, 2023) Smith, Chelsey A.; Chang, Megan M.; Kundrod, Kathryn A.; Novak, Emilie N.; Parra, Sonia G.; López, Leticia; Mavume, Celda; Lorenzoni, Cesaltina; Maza, Mauricio; Salcedo, Mila P.; Carns, Jennifer L.; Baker, Ellen; Montealegre, Jane; Scheurer, Michael; Castle, Philip E.; Schmeler, Kathleen M.; Richards-Kortum, Rebecca R.; Bioengineering
    Cervical cancer is a leading cause of cancer death for women in low-resource settings. The World Health Organization recommends that cervical cancer screening programs incorporate HPV DNA testing, but available tests are expensive, require laboratory infrastructure, and cannot be performed at the point-of-care. We developed a two-dimensional paper network (2DPN), hybrid-capture, signal amplification assay and a point-of-care sample preparation protocol to detect high-risk HPV DNA from exfoliated cervical cells within an hour. The test does not require expensive equipment and has an estimated cost of <$3 per test without the need for batching. We evaluated performance of the paper HPV DNA assay with short synthetic and genomic HPV DNA targets, HPV positive and negative cellular samples, and two sets of clinical samples. The first set of clinical samples consisted of 16 biobanked, provider-collected cervical samples from a study in El Salvador previously tested with careHPV and subsequently tested in a controlled laboratory environment. The paper HPV DNA test correctly identified eight of eight HPV-negative clinical samples and seven of eight HPV-positive clinical samples. We then performed a field evaluation of the paper HPV DNA test in a hospital laboratory in Mozambique. Cellular controls generated expected results throughout field testing with fully lyophilized sample preparation and 2DPN reagents. When evaluated with 16 residual self-collected cervicovaginal samples previously tested by the GeneXpert HPV assay (“Xpert”), the accuracy of the HPV DNA paper test in the field was reduced compared to testing in the controlled laboratory environment, with positive results obtained for all eight HPV-positive samples as well as seven of eight HPV-negative samples. Further evaluation showed reduction in performance was likely due in part to increased concentration of exfoliated cells in the self-collected clinical samples from Mozambique compared with provider-collected samples from El Salvador. Finally, a formal usability assessment was conducted with users in El Salvador and Mozambique; the assay was rated as acceptable to perform after minimal training. With additional optimization for higher cell concentrations and inclusion of an internal cellular control, the paper HPV DNA assay offers promise as a low-cost, point-of-care cervical cancer screening test in low-resource settings.
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    A mobile-phone based high-resolution microendoscope to image cervical precancer
    (Public Library of Science, 2019) Grant, Benjamin D.; Quang, Timothy; Possati-Resende, Júlio César; Scapulatempo-Neto, Cristovam; Matsushita, Graziela de Macedo; Mauad, Edmundo Carvalho; Stoler, Mark H.; Castle, Philip E.; Fregnani, José Humberto Tavares Guerreiro; Schmeler, Kathleen M.; Richards-Kortum, Rebecca; Bioengineering
    Nearly 90% of cervical cancer cases and deaths occur in low- and middle-income countries that lack comprehensive national HPV immunization and cervical cancer screening programs. In these settings, it is difficult to implement screening programs due to a lack of infrastructure and shortage of trained personnel. Screening programs based on visual inspection with acetic acid (VIA) have been successfully implemented in some low-resource settings. However, VIA has poor specificity and up to 90% of patients receiving treatment based on a positive VIA exam are over-treated. A number of studies have suggested that high-resolution cervical imaging to visualize nuclear morphology in vivo can improve specificity by better distinguishing precancerous and benign lesions. To enable high-resolution imaging in low-resource settings, we developed a portable, low-cost, high-resolution microendoscope that uses a mobile phone to detect and display images of cervical epithelium in vivo with subcellular resolution. The device was fabricated for less than $2,000 using commercially available optical components including filters, an LED and triplet lenses assembled in a 3D-printed opto-mechanical mount. We show that the mobile high-resolution microendoscope achieves similar resolution and signal-to-background ratio as previously reported high-resolution microendoscope systems using traditional cameras and computers to detect and display images. Finally, we demonstrate the ability of the mobile high-resolution microendoscope to image normal and precancerous squamous epithelium of the cervix in vivo in a gynecological referral clinic in Barretos, Brazil.
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    A novel tailed primer nucleic acid test for detection of HPV 16, 18 and 45 DNA at the point of care
    (Springer Nature, 2023) Chang, Megan M.; Ma, Ariel; Novak, Emilie Newsham; Barra, Maria; Kundrod, Kathryn A.; Montealegre, Jane Richards; Scheurer, Michael E.; Castle, Philip E.; Schmeler, Kathleen; Richards-Kortum, Rebecca; Bioengineering
    Cervical cancer is a leading cause of death for women in low-resource settings despite being preventable through human papillomavirus (HPV) vaccination, early detection, and treatment of precancerous lesions. The World Health Organization recommends high-risk HPV (hrHPV) as the preferred cervical cancer screening strategy, which is difficult to implement in low-resource settings due to high costs, reliance on centralized laboratory infrastructure, and long sample-to-answer times. To help meet the need for rapid, low-cost, and decentralized cervical cancer screening, we developed tailed primer isothermal amplification and lateral flow detection assays for HPV16, HPV18, and HPV45 DNA. We translated these assays into a self-contained cartridge to achieve multiplexed detection of three hrHPV genotypes in a disposable cartridge. The developed test achieves clinically relevant limits of detection of 50–500 copies per reaction with extracted genomic DNA from HPV-positive cells. Finally, we performed sample-to-answer testing with direct lysates of HPV-negative and HPV-positive cell lines and demonstrated consistent detection of HPV16, HPV18, and HPV45 with 5000–50,000 cells/mL in < 35 min. With additional optimization to improve cartridge reliability, incorporation of additional hrHPV types, and validation with clinical samples, the assay could serve as a point-of-care HPV DNA test that improves access to cervical cancer screening in low-resource settings.
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    A paper-based immunoassay to determine HPV vaccination status at the point-of-care
    (Elsevier, 2016) Grant, Benjamin D.; Smith, Chelsey A.; Castle, Philip E.; Scheurer, Michael E.; Richards-Kortum, Rebecca; Bioengineering
    Objective: To develop and evaluate a paper-based point-of-care HPV serology test to determine if an individual has received two or more HPV immunizations. Methods: The paper-based immunoassay was constructed using a nitrocellulose lateral flow strip with adsorbed HPV16 virus-like particles serving as the capturing moiety. Three capture zones containing virus-like particles were placed in series to allow for visual discrimination between high and low HPV16 plasma antibody concentrations. A plasma separation membrane was used to allow whole blood to be applied directly to the assay. All reagents were dried on glass fiber pads during device fabrication and were rehydrated with buffer at the time of use. A pilot study consisting of 35 subjects with a history of zero, one, two or three HPV vaccines was conducted to evaluate the immunoassay. The completed paper-based immunoassays were scanned for visual interpretation by three researchers who were blinded to the true results and separately evaluated quantitatively using MATLAB. Results: For the 28 tests valid for analysis, fifteen subjects reported receiving two or more HPV vaccines, three reported receiving one, and ten reported having no HPV vaccinations. The paper-based immunoassays for all fifteen subjects who reported having received two or more HPV vaccines were judged positive by all researchers. Twelve of the thirteen tests from individuals reporting one or zero vaccinations were deemed negative by all observers. One test from an unvaccinated individual was judged positive by two out of three reviewers. Quantitatively, all tests were correctly separated between the two groups. Conclusions: We successfully designed and tested a HPV serology test amenable to the point-of-care. The device showed promising results in a pilot study for discriminating between those who received two or more HPV vaccinations and those who did not. Furthermore, this device offers a platform for producing other semi-quantitative point-of-care serological tests.