Expression Profiling of Adipogenic and Anti-Adipogenic MicroRNA Sequences following Methylmercury Exposure in Caenorhabditis elegans.

MicroRNA (miRNA) are important regulators of gene expression that respond not only to developmental and pathological cues, but also to environmental stimuli. Dyslipidemia is a hallmark of metabolic conditions and has been shown to significantly affect the expression of circulating miRNA sequences. Recently, our lab has shown that the environmental toxicant methylmercury (MeHg) causes dyslipidemia in the Caenorhabditis elegans model organism. While 10 and 20 µM MeHg increases the expression of adipogenic transcription factors and lipid-binding proteins in worms, there is limited information on how the toxicant affects the miRNA regulators of these genes. We hypothesized that MeHg would increase the expression of adipogenic miRNA sequences and/or decrease the expression of anti-adipogenic miRNA sequences. We further hypothesized that the target mRNA sequences for the miRNAs affected by MeHg would be consequently altered. We selected three potentially adipogenic (mir-34, mir-124, and mir-355) and three potentially anti-adipogenic (mir-240, mir-786, and let-7) miRNA sequences homologous to known human miRNA sequences altered in obesity, and quantified their levels 24 h and 48 h post MeHg treatment. At 24 h post exposure, MeHg significantly increased expression of both the adipogenic and anti-adipogenic miRNA sequences 1.5-3x above untreated control. By 48 h post exposure, only the adipogenic miRNA sequences were elevated, while the anti-adipogenic miRNA sequences were decreased by 50% compared to untreated control. These data suggest that there are developmental changes in miRNA expression over time following MeHg exposure. We next selected one target mRNA sequence for each miRNA sequence based on miRNA-mRNA relationships observed in humans. MeHg altered the gene expression of all the target genes assayed. Except for mir-34, all the tested miRNA-mRNA sequences showed a conserved relationship between nematode and humans. To determine whether the selected miRNA sequences were involved in lipid accumulation in response to MeHg, lipid storage was investigated in transgenic worm strains that lacked the specific miRNA strains. Of the six strains investigated, only the mir-124 and let-7 mutant worms had lipid storage levels that were statistically different from wild type, suggesting that these two sequences can be potential mediators of MeHg-induced lipid dysregulation.

Perioperative Topical Antisepsis and Surgical Site Infection in Patients Undergoing Upper Aerodigestive Tract Reconstruction.

Importance: Surgical site infections (SSIs) after vascularized reconstruction of the upper aerodigestive tract (UADT) are associated with considerable morbidity. The association between perioperative prophylaxis practices, particularly topical antisepsis, and SSIs remains uncertain. Objective: To assess the association between perioperative topical antisepsis and SSIs in patients undergoing vascularized reconstruction of the UADT. Design, Setting, and Participants: This cohort study included patients from 12 academic tertiary care centers over an 11-month period, from July 1, 2020, to June 1, 2021. Patients undergoing open surgical procedures requiring a communication between the UADT and cervical skin with a planned regional pedicled flap, free flap, or both were included. Patients with an active infection at the time of surgical procedure were excluded. Main Outcomes and Measures: The primary outcome measure was an SSI within 30 days of surgery. The association of demographic characteristics, perioperative antibiotic prophylaxis, surgical technique, and postoperative care with SSIs was assessed using univariable and multivariable analyses. The relative risk ratio and 95% CIs for developing SSI were calculated for each of the variables based on predetermined categories. Variables for which the relative risk 95% CI did not include the value of zero effect (relative risk = 1.00) were included in the multivariable model. Results: A total of 554 patients (median age, 64 years; range, 21-95 years; 367 men [66.2%]) were included. Cancer ablation was the most frequent reason for surgery (n = 480 [86.6%]). Overall, the SSI rate was 20.9% (n = 116), with most infections involving the head and neck surgical site only (91 [78.4%]). The median time to SSI diagnosis was 11 days (range, 1-28 days). Topical antisepsis mucosal preparation was performed preoperatively in 35.2% (195) and postoperatively in 52.2% (289) of cases. Ampicillin and sulbactam was the most common systemic antibiotic prophylaxis agent used (n = 367 [66.2%]), with 24 hours being the most common duration (n = 363 [65.5%]). On multivariable analysis, preoperative topical antisepsis mucosal preparation (odds ratio [OR], 0.49; 95% CI, 0.30-0.77) and systemic prophylaxis with piperacillin and tazobactam (OR, 0.42; 95% CI, 0.21-0.84) were associated with a decreased risk of a postoperative SSI. The use of an osseous vascularized flap was associated with an increased risk of postoperative SSI (OR, 1.76; 95% CI, 1.13-2.75). Conclusions and Relevance: Findings of this study suggest that preoperative topical antisepsis mucosal preparation was independently associated with a decreased risk of SSIs in a 12-center multi-institutional cohort. Further investigation of the association between individual perioperative practices and the incidence of postoperative SSIs is necessary to develop evidence-based protocols to reduce SSIs after UADT reconstruction.

MicroRNA Expression Influences Methylmercury-Induced Lipid Accumulation and Mitochondrial Toxicity in Caenorhabditis elegans.

Metabolic effects of methylmercury (MeHg) are gaining wider attention. We have previously shown that MeHg causes lipid dysregulation in Caenorhabditis elegans (C. elegans), leading to altered gene expression, increased triglyceride levels and lipid storage, and altered feeding behaviors. Transcriptional regulators, such as transcription factors and microRNAs (miRNAs), have been shown to regulate lipid storage, serum triglycerides, and adipogenic gene expression in human and rodent models of metabolic diseases. As we recently investigated adipogenic transcription factors induced by MeHg, we were, therefore, interested in whether MeHg may also regulate miRNA sequences to cause metabolic dysfunction. Lipid dysregulation, as measured by triglyceride levels, lipid storage sites, and feeding behaviors, was assessed in wild-type (N2) worms and in transgenic worms that either were sensitive to miRNA expression or were unable to process miRNAs. Worms that were sensitive to the miRNA expression were protected from MeHg-induced lipid dysregulation. In contrast, the mutant worms that were unable to process miRNAs had exacerbated MeHg-induced lipid dysregulation. Concurrent with differential lipid homeostasis, miRNA-expression mutants had altered MeHg-induced mitochondrial toxicity as compared to N2, with the miRNA-sensitive mutants showing mitochondrial protection and the miRNA-processing mutants showing increased mitotoxicity. Taken together, our data demonstrate that the expression of miRNAs is an important determinant in MeHg toxicity and MeHg-induced metabolic dysfunction in C. elegans.

Methylmercury-Induced Metabolic Alterations in Caenorhabditis elegans Are Diet-Dependent.

Methylmercury (MeHg) is a well-known neurotoxicant; however, its role in metabolic diseases has been gaining wider attention. Chronic exposure to MeHg in human populations shows an association with diabetes mellitus and metabolic syndrome (MS). As the incidences of both obesity and MS are on the rise globally, it is important to understand the potential role of MeHg in the development of the disease. There is a dearth of information on dietary interactions between MeHg and lipids, which play an important role in developing MS. We have previously shown that MeHg increases food seeking behaviors, lipid levels, fat storage, and pro-adipogenic gene expression in C. elegans fed the standard OP50 Escherichia coli diet. However, we hypothesized that these metabolic changes could be prevented if the worms were fed a bacterial diet lower in lipid content. We tested whether C. elegans developed metabolic alterations in response to MeHg if they were fed two alternative E. coli strains (HT115 and HB101) that are known absorb significantly less lipids from their media. Additionally, to explore the effect of a high-lipid and high-cholesterol diet on MeHg-induced metabolic dysfunction, we supplemented the OP50 strain with twice the standard concentration of cholesterol in the nematode growth media. Wild-type worms fed either the HB101 or HT115 diet were more resistant to MeHg than the worms fed the OP50 diet, showing a significant right-hand shift in the dose-response survival curve. Worms fed the OP50 diet supplemented with cholesterol were more sensitive to MeHg, showing a significant left-hand shift in the dose-response survival curve. Changes in sensitivity to MeHg by differential diet were not due to altered MeHg intake in the worms as measured by inductively coupled mass spectrometry. Worms fed the low-fat diets showed protection from MeHg-induced metabolic changes, including decreased food consumption, lower triglyceride content, and lower fat storage than the worms fed either of the higher-fat diets. Oxidative stress is a common characteristic of both MeHg exposure and high-fat diets. Worms fed either OP50 or OP50 supplemented with cholesterol and treated with MeHg had significantly higher levels of reactive oxygen species, carbonylated proteins, and loss of glutathione than the worms fed the HT115 or HB101 low-lipid diets. Taken together, our data suggest a synergistic effect of MeHg and dietary lipid levels on MeHg toxicity and fat metabolism in C. elegans, which may affect the ability of MeHg to cause metabolic dysfunction.

Mucosa-Associated Lymphoid Tissue Lymphoma of the Larynx.

BACKGROUND: Mucosa-associated lymphoid tissue (MALT) lymphomas are a subtype of non-Hodgkin lymphoma stemming from marginal zone B-cells. In this case report, we present two patients with an extremely rare localization of MALT lymphoma to the larynx. METHODS: Case 1 is of a 78-year-old male presenting with a six-month history of progressive hoarseness with a past medical history significant for marginal zone lymphoma of the right orbit. Diagnosis was confirmed with a biopsy for extranodal marginal zone B-cell lymphoma of MALT type. An FDG-PET scan was done but did not show any sign of FDG avid malignancy, including at the primary site. Case 2 is a 60-year-old female presenting with one year of worsening throat discomfort, intermittent cough, and dyspnea with exertion. Pathology confirmed a diagnosis of extranodal marginal zone B-cell lymphoma of MALT type. RESULTS: Case 1 was treated with low-dose radiation at 4 Gy delivered over two fractions of 2 Gy each. Upon completion of radiation treatment, he reported a resolution of his hoarseness and normalization of his voice. A four-month follow-up in May 2018 with flexible nasolaryngoscopy revealed a normal exam with fully mobile vocal folds bilaterally and no evidence of left false vocal fold submucosal mass. At seven months following treatment, the patient died unexpectedly of unknown causes. Case 2 was treated with radiation at 30 Gy in 15 fractions over the course of one month. Following completion of radiation therapy, she had improvement of her sore throat, nausea, dysphagia, dysgeusia, and dry mouth. At 21-month follow-up, she had no evidence of disease. CONCLUSION: This case report demonstrates that MALT lymphoma can present with much more benign and subtle symptoms. This highlights the importance of clinicians to keep broad differentials and consider MALT lymphomas in the setting of laryngeal masses.

An unusual presentation of papillary thyroid carcinoma in a pediatric patient: A case report.

Cystic neck masses in the pediatric population are common but rarely concerning for malignancy. Given this typically benign nature, they are frequently managed conservatively. Here we present an unusual case of a waxing and waning cystic neck mass in a pediatric patient. After surgical removal, the mass was found to be metastatic papillary thyroid cancer. This is a unique presentation in the pediatric age group that has not yet been described. Based on this case, we suggest an expanded differential in any workup for a cystic neck mass to include papillary thyroid carcinoma, regardless of the patient's age.

Penetrating Neck Trauma: An Unusual Case Presentation and Review of the Literature.

OBJECTIVES: The aim of this report is to describe a case of a retained projectile metal object to the neck that occurred after airbag deployment during a motor vehicle accident. METHODS: Case report with literature review. RESULTS: After a motor vehicle accident on the interstate, a 19-year-old man presents to the emergency department for several open extremity fractures, a neck laceration, and a C1 lateral mass fracture. The trauma surgery team repaired the neck laceration with no further evidence of injury. Several weeks later on follow-up, the patient presents with dysphagia and pain when turning his head to the right. A repeat computed tomography angiography (CTA) scan revealed a metallic foreign body in the left posterior pharyngeal, prevertebral soft tissues, which was subsequently removed during exploratory surgery 2 months after his initial accident. CONCLUSIONS: This is the first report, to our knowledge, of a projectile metal object to the neck that may be related to airbag deployment. The car involved in this accident was under recall for airbags that were associated with projectile objects, which warrants further investigation into the possible risks of such airbags.