Publications by authors named "S Roark"
Per- and polyfluoroalkyl substances (PFAS) accumulate at the air-water interface of the surface microlayer (SML) on marine and freshwater bodies. In order to determine if including the SML when sampling bulk surface water leads to a high bias in measured PFAS concentrations, a pilot study and a full field study were conducted. The pilot study conducted at two sites was aimed at determining the analytical precision and small-scale (~1 m) spatial variability in concentrations of PFAS in bulk water and the SML.
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- Malakoplakia is a rare inflammatory disorder mainly seen in immunocompromised patients, characterized by an inability of macrophages to effectively kill bacteria.
- Although it usually occurs in the genitourinary and gastrointestinal regions, this report highlights a rare case where malakoplakia affected the maxilla and maxillary alveolar ridge mucosa, marking a unique instance of oral cavity involvement.
- Diagnostic stains revealed specific patterns indicating malakoplakia without evidence of microbial infection, emphasizing the need for clinicians and pathologists to consider this condition when evaluating lesions in immunosuppressed patients.
CD1a is not effective in distinguishing calcifying epithelial odontogenic tumors from amyloid-rich central odontogenic fibroma.
Oral Surg Oral Med Oral Pathol Oral Radiol
January 2024
Article Synopsis
- The study addresses the challenge of differentiating between two dental tumors: non-calcifying variant of calcifying epithelial odontogenic tumor (NCLC-CEOT) and amyloid-rich central odontogenic fibroma (AR-COdF), focusing on the role of CD1a positivity in their diagnosis.
- Researchers analyzed a series of cases with distinct histopathological features and stained them for CD1a and amyloid to determine their relationships and diagnostic criteria.
- Results indicated that while CD1a positivity appears in both CEOTs and NCLC-CEOTs, it does not reliably distinguish them from AR-COdFs, suggesting that histopathologic criteria should take precedence over staining results.
Few studies have determined the toxicity of perfluoralkyl substances (PFAS) to aquatic invertebrates. We exposed Chironomus dilutus to 6 different PFAS to assess single-chemical toxicity and relative or proportional toxicity among substances. A 10-d range-finding test was conducted to inform 20-d assays for the following PFAS: perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorobutanesulfonic acid (PFBS), perfluorohexanesulfonic acid (PFHxS), and perfluoroheptanoic acid (PFHpA).
View Article and Find Full Text PDFConsiderations for toxicity experiments and risk assessments with PFAS mixtures.
Integr Environ Assess Manag
July 2021
Per- and polyfluoroalkyl substances (PFAS) have been around for decades and have been the subject of laboratory and field research studies for nearly as long. Although attention to PFAS has grown in recent years, many unanswered questions remain. Accordingly, the number of research projects designed to improve our understanding of PFAS toxicity, bioaccumulation, and biomagnification, and to improve our ability to predict the interactions of PFAS mixtures, is also increasing.
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