Next-Generation Sequencing in Sporadic Medullary Thyroid Cancer Patients: Mutation Profile and Disease Aggressiveness.

Context: Next-generation sequencing (NGS) analysis of sporadic medullary thyroid carcinoma (sMTC) has led to increased detection of somatic mutations, including RET M918T, which has been considered a negative prognostic indicator. Objective: This study aimed to determine the association between clinicopathologic behavior and somatic mutation identified on clinically motivated NGS. Methods: In this retrospective cohort study, patients with sMTC who underwent NGS to identify somatic mutations for treatment planning were identified. Clinicopathologic factors, time to distant metastatic disease (DMD), disease-specific survival (DSS), and overall survival (OS) were compared between somatic mutations. Results: Somatic mutations were identified in 191 sMTC tumors, including RET M918T (53.4%), other RET codons (10.5%), RAS (18.3%), somatic RET indels (8.9%), and RET/RAS wild-type (WT) status (8.9%). The median age at diagnosis was 50 years (range, 11-83); 46.1% were female. When comparing patients with RET M918T, RET-Other, and RET WT (which included RAS and RET/RAS WT), there were no differences in sex, TNM category, systemic therapy use, time to DMD, DSS, or OS. On multivariate analysis, older age at diagnosis (HR 1.05, P < .001; HR 1.06, P< .001) and M1 stage at diagnosis (HR 3.17, P = .001; HR 2.98, P = .001) were associated with decreased DSS and OS, respectively, but mutation cohort was not. When comparing RET M918T to RET indels there was no significant difference in time to DMD, DSS, or OS between the groups. Conclusion: Somatic RET mutations do not portend compromised DSS or OS in a cohort of sMTC patients who underwent clinically motivated NGS.

Is there a role for liquid biopsy in the surveillance of parathyroid carcinoma?

BACKGROUND: Parathyroid carcinoma is a rare malignancy with high recurrence rates. Liquid biopsy is a stratifying tool in disease recurrence/progression in other malignant processes. This study sought to assess the feasibility and application of liquid biopsy in parathyroid carcinoma and its impact on surveillance. METHODS: Retrospective review of a prospectively maintained database of adults treated for parathyroid carcinoma at a tertiary care center (2017-2023). Demographics, clinical characteristics, and laboratory variables were collected. Circulating cell-free deoxyribonucleic acid enrichment and circulating tumor cell enumeration were obtained from serial blood samples. RESULTS: A total of 25 patients were identified-64% were male patients, with a median age of 56 years (interquartile range 45-63). Fifty blood samples were collected postoperatively. At first, circulating tumor cell enumeration, 56% (14/25) of patients had no evidence of disease, and 32% (8/25) had distant metastasis. Median follow-up was 53 months (interquartile range 23-107). At the last follow-up, 40% (10/25) of patients were found to have distant metastasis. Serial circulating tumor cell enumeration was performed in 52% of patients, median highest circulating tumor cell was (interquartile range 1-22). Circulating cell-free deoxyribonucleic acid was assessed in 64% of patients (16/25). There was no difference in circulating tumor cells or circulating cell-free deoxyribonucleic acid between those with distant metastasis and those without distant metastasis. The most common mutation identified was TP53, present in 88% of circulating cell-free deoxyribonucleic acid samples with a mutation. Circulating cell-free deoxyribonucleic acid and parathyroid hormone levels were not found to have any association (r = -0.27, P = .39), but parathyroid hormone and circulating tumor cell had a linear relationship (r = 0.76, P < .001). CONCLUSION: Liquid biopsy appears to be a feasible tool in parathyroid carcinoma surveillance. The relationship between circulating cell-free deoxyribonucleic acid and parathyroid hormone levels remains unclear, and the association between circulating tumor cell enumeration and parathyroid hormone levels may be impactful. The finding that TP53 mutation is more prevalent in patients with distant metastasis may impact further management.

Beyond the three P's: adrenal involvement in MEN1.

Adrenal lesions (ALs) are often detected in patients with multiple endocrine neoplasia type 1 (MEN1). However, they are not well described in MEN1, making their clinical management unclear. This study examined the prevalence and outcomes of ALs found in MEN1. We performed a retrospective chart review of patients diagnosed with MEN1 from 1990 to 2021. ALs were diagnosed using abdominal or thoracic imaging and classified as being unilateral or bilateral, having single or multiple nodules, and as having diffuse enlargement or not. Measurable nodular lesions were analyzed for their size and growth over time. Patients' clinical and radiographic characteristics were collected. We identified 382 patients with MEN1, 89 (23.3%) of whom had ALs. The mean age at detection was 47 ± 11.9 years. We documented 101 measurable nodular lesions (mean size, 17.5 mm; range, 3-123 mm). Twenty-seven nodules (26.7%) were smaller than 1 cm. Watchful waiting was indicated in 79 (78.2%) patients, of whom 28 (35.4%) had growing lesions. Functional lesions were diagnosed in 6 (15.8%) of 38 that had functional work-up (diagnoses: pheochromocytoma (n = 2), adrenocorticotropic hormone-dependent hypercortisolism (n = 2), hyperandrogenism (n = 1), hyperaldosteronism (n = 1)); surgery was indicated for 5 (83.3%; n = 12 nodules), 2 of whom had bilateral, diffuse adrenal enlargement. Two patients were diagnosed with adrenocortical carcinoma and two with neoplasms of uncertain malignant potential. Radiographic or clinical progression of ALs is uncommon. Malignancy should be suspected on the basis of a lesion's growth rate and size. A baseline hormonal work-up is recommended, and no further biochemical work-up is suggested when the initial assessment shows nonfunctioning lesions.

Advances in Endocrine Surgery.

Recent changes in the landscape of endocrine surgery include a shift from total thyroidectomy for almost all patients with papillary thyroid cancer to the incorporation of thyroid lobectomy for well-selected patients with low-risk disease; minimally invasive parathyroidectomy with, and potentially without, intraoperative parathyroid hormone monitoring for patients with well-localized primary hyperparathyroidism; improvement in the management of parathyroid cancer with the incorporation of immune checkpoint blockade and/or targeted therapies; and the incorporation of minimally invasive techniques in the management of patients with benign tumors and selected secondary malignancies of the adrenal gland.

Pheochromocytoma recurrence in hereditary disease: does a cortical-sparing technique increase recurrence rate?

BACKGROUND: Posterior retroperitoneoscopic adrenalectomy is an appealing approach for patients with hereditary pheochromocytoma and lends well to cortex preservation. We sought to examine pheochromocytoma recurrence in patients with hereditary pheochromocytoma in the era of posterior retroperitoneoscopic adrenalectomy and evaluate the predictors of recurrence. METHODS: Patients with hereditary pheochromocytoma who underwent adrenalectomy for pheochromocytoma between 1995 and 2020 with biochemical cure and follow-up >1 year were identified. Recurrence was defined as plasma metanephrines above the upper limit of normal with radiographic evidence of disease in the ipsilateral adrenal bed. RESULTS: Seventy-eight hereditary pheochromocytoma patients (median age = 32.4 years; 60.3% women) underwent 114 adrenalectomies for pheochromocytoma. Of these patients, 40 had multiple endocrine neoplasia type 2A (51.3%), 10 had multiple endocrine neoplasia type B (12.8%), 17 had von Hippel-Lindau disease (21.8%), and 11 had neurofibromatosis type 1 (14.1%). Thirty-eight adrenalectomies (33.3%) were performed before the introduction of posterior retroperitoneoscopic adrenalectomy and 76 (66.7%) after. Cortical-sparing technique was performed in 62 (54.4%) adrenalectomies, with no difference in its use before and after posterior retroperitoneoscopic adrenalectomy introduction (P > .05). During a median follow-up of 80.7 months (interquartile range 43.4-151.2), 12 ipsilateral recurrences (10.5%) were identified. There was no difference in recurrence before and after the introduction of posterior retroperitoneoscopic adrenalectomy or by surgical technique or approach of the entire cohort (P > .05). Recurrence was more common in those with RET M918T mutation (23.5% vs 8.2%; P = .05). Patients with RET M918T mutations had a shorter recurrence-free survival (P = .013). On multivariate analysis, only RET M918T mutation was independently associated with an increased recurrence risk (hazard ratio = 4.30; 95% confidence interval, 1.26-14.66; P = .019). CONCLUSION: The introduction of posterior retroperitoneoscopic adrenalectomy did not influence the recurrence rate after adrenalectomy for hereditary pheochromocytoma patients. Patients with a RET M918T germline mutation are at increased risk for pheochromocytoma recurrence and may benefit from initial total adrenalectomy.

Parathyroidectomy for Normocalcemic Primary Hyperparathyroidism is Associated with Improved Bone Mineral Density Regardless of Postoperative Parathyroid Hormone Levels.

BACKGROUND: Biochemical cure in normocalcemic primary hyperparathyroidism (nPHPT) is defined as parathyroid hormone (PTH) level normalization 6 months after parathyroidectomy. However, recent studies show that a significant number of nPHPT patients have persistent PTH elevation postoperatively. We sought to correlate changes in PTH levels with skeletal outcomes after parathyroidectomy in nPHPT patients. METHODS: Adult patients who underwent parathyroidectomy at a tertiary referral center for sporadic PHPT between 2010 and 2020 were reviewed. Pre- and postoperative (6 months, 18 months, and last follow-up) laboratory and bone mineral densities (BMD) were recorded. Primary outcome was 18-month postoperative BMD change in the lumbar spine (LS), total hip (TH) and femoral neck (FN) in normocalcemic and hypercalcemic PHPT (hPHPT) patients. RESULTS: Of 661 patients included, 68 had nPHPT. nPHPT patients frequently had multigland disease (31% vs. 18%, p = 0.014), more bilateral cervical explorations (22% vs. 13%, p = 0.042), and fewer achieved biochemical cure (76% vs. 95%, p < 0.001) than hPHPT patients. Twenty-eight nPHPT patients had BMD data for comparison. Overall, nPHPT patients had improvement in the LS (1.84%, p = 0.002) and TH (1.64%, p = 0.014). When stratified by postoperative PTH levels, nPHPT patients with persistent PTH elevation had more BMD improvement at the TH than those who normalized PTH (3.73% vs. - 0.83%, p = 0.017). There was no difference in improvement at the LS or FN (p = NS). CONCLUSION: Parathyroidectomy is associated with improved BMD in nPHPT patients with bone disease. Although one in four nPHPT patients had elevated postoperative PTH levels persisting throughout the study, BMD improvement was still seen regardless of postoperative PTH level normalization.

Differences in Clinicopathologic Behavior of Oncocytic Adrenocortical Neoplasms and Conventional Adrenocortical Carcinomas.

BACKGROUND: Oncocytic adrenocortical neoplasms (OANs) are rare endocrine tumors that present as a spectrum from benign to malignant. The outcomes after surgical resection of the oncocytic variant of adrenocortical carcinoma remain poorly understood. We sought to characterize the clinicopathologic features of OAN and compare oncocytic adrenocortical carcinoma (OAC) with conventional adrenocortical carcinoma (ACC). PATIENTS AND METHODS: Adult patients who underwent adrenalectomy for OAN or ACC between January 1990 and September 2020 were identified. Demographics, clinicopathologic factors, American Joint Committee on Cancer stage, and cancer-related outcomes were reviewed. A matched cohort analysis of disease-free survival (DFS) and overall survival (OS) was performed between patients with OACs and those with ACCs. RESULTS: Forty-one patients with OAN and 214 patients with ACC were included. The OAN cohort median age was 45.2 years [interquartile ratio (IQR) 38.5-54.0 years], and 61.0% were female. OANs were benign (n = 11), of uncertain malignant potential (UMP, n = 9), or OAC (n = 21). Disease recurrence occurred in 12 (57.1%) patients with OAC compared with 1 (11.1%) and 0 patients with UMP or benign OAN, respectively (p < 0.001). Seven (33.3%) patients with OAC died during follow-up compared with 0 patients with UMP or benign OAN (p = 0.020). Kaplan-Meier survival analysis found no difference in DFS between ACC and OAC groups before (p = 0.218) and after 2:1 matching (p = 0.417). Overall survival was shorter for patients who had ACC compared with those who had OAC (p = 0.031), but the difference was not evident with matched analysis (p = 0.200). CONCLUSIONS: OAN presents as a spectrum from benign indolent tumors to aggressive carcinomas. OACs demonstrate similar clinicopathologic behavior and recurrence-free and overall survival when matched to conventional ACCs.

Recurrence after successful parathyroidectomy-Who should we worry about?

BACKGROUND: Preventing cervical reoperations is important-especially after parathyroidectomy. We sought to examine early predictors of recurrence of primary hyperparathyroidism after surgical cure. METHODS: Adult patients with sporadic primary hyperparathyroidism treated with parathyroidectomy between September 1, 1997, and September 1, 2019, with confirmed eucalcemia at 6 months postoperatively were identified. Recurrence was defined as hypercalcemia (>10.2 mg/dL) with an elevated or nonsuppressed parathyroid hormone level on subsequent follow-up. RESULTS: Parathyroidectomy was performed in 522 patients (median age, 62.1 years, 77% female) with the majority undergoing planned minimally invasive parathyroidectomy (85.4%, n = 446). After a median follow-up of 30.9 months, 13 patients (2.5%) recurred (median time to recurrence 50.2 months, interquartile range 27.9-66.5), all of whom underwent planned minimally invasive parathyroidectomy (n = 13/446, 2.9%). Recurrence was more common in those with higher (but still normal) 6-month calcium (10.1 vs 9.3 mg/dL, P < .001) or parathyroid hormone values (64 vs 46 pg/mL, P < .01). Multivariate analysis revealed that age >66.5 years, calcium ≥9.8mg/dL and parathyroid hormone ≥80 pg/mL at 6 months were associated with increased risk of recurrence. In addition, the presence of at least 1 preoperative imaging study that conflicted with intraoperative findings among minimally invasive parathyroidectomy patients (n = 446) was associated with increased risk of recurrence (hazard ratio 4.93, 95% confidence interval 1.25-16.53, P = .016). CONCLUSION: Recurrence of sporadic primary hyperparathyroidism after initial surgical cure in the era of minimally invasive parathyroidectomy is 2.5%. Identification of those at risk for recurrence using 6-month serum calcium ≥9.8 mg/dL, parathyroid hormone ≥80 pg/mL, and/or potentially conflicting localization studies may inform surveillance strategies.

Parathyroid Surgery: What Radiologists Need to Know.

Surgical intervention remains the mainstay of treatment of hyperparathyroidism and provides the highest chance at cure. After the disease is confirmed by biochemical testing, surgeons must use a combination of patient clinical history and radiographic imaging to determine the most appropriate surgical strategy. Through either minimally invasive parathyroidectomy or bilateral cervical exploration, surgeons provide high rates of cure for hyperparathyroidism with low rates of persistence or recurrence.

Preoperative Trapped Lung Is Associated With Increased Mortality After Orthotopic Liver Transplantation.

INTRODUCTION: Trapped lung, characterized by atelectatic lung unable to reexpand and fill the thoracic cavity due to a restricting fibrous visceral pleural peel, is occasionally seen in patients with end-stage liver disease complicated by hepatic hydrothorax. Limited data suggest that trapped lung prior to orthotopic liver transplantation may be associated with poor outcomes. RESEARCH QUESTION: What is the clinical significance of trapped lung in patients receiving orthotopic liver transplantation? DESIGN: We performed a retrospective analysis of patients who underwent liver transplantation over an 8-year period. Baseline clinical characteristics and postoperative outcomes of adult patients with trapped lung were analyzed and compared to the overall cohort of liver transplant recipients and controls matched 3:1 based on age, sex, Model for End-Stage Liver Disease (MELD) score, and presence of pleural effusion. RESULTS: Of the 1193 patients who underwent liver transplantation, we identified 20 patients (1.68%) with trapped lung. The probability of 1 and 2-year survival were 75.0% and 57.1%, compared to 85.6% and 80.4% (p = 0.02) in all liver transplant recipients and 87.9% and 81.1% (p = 0.03) in matched controls respectively. Patients with trapped lung had a longer hospital length of stay compared to the total liver transplant population (geometric mean 54.9 ± 8.4 vs. 27.2 ± 0.7 days, p ≤ 0.001), when adjusted for age and MELD score. DISCUSSION: Patients with trapped prior to orthotopic liver transplantation have increased probability of mortality as well as increased health care utilization. This is a small retrospective analysis, and further prospective investigation is warranted.

Angiopoietin-2 predicts morbidity in adults with Fontan physiology.

Morbidity in patients with single-ventricle Fontan circulation is common and includes arrhythmias, edema, and pulmonary arteriovenous malformations (PAVM) among others. We sought to identify biomarkers that may predict such complications. Twenty-five patients with Fontan physiology and 12 control patients with atrial septal defects (ASD) that underwent cardiac catheterization were included. Plasma was collected from the hepatic vein and superior vena cava and underwent protein profiling for a panel of 20 analytes involved in angiogenesis and endothelial dysfunction. Ten (40%) of Fontan patients had evidence of PAVM, eighteen (72%) had a history of arrhythmia, and five (20%) were actively in arrhythmia or had a recent arrhythmia. Angiopoietin-2 (Ang-2) was higher in Fontan patients (8,875.4 ± 3,336.9 pg/mL) versus the ASD group (1,663.6 ± 587.3 pg/mL, p < 0.0001). Ang-2 was higher in Fontan patients with active or recent arrhythmia (11,396.0 ± 3,457.7 vs 8,118.2 ± 2,795.1 pg/mL, p < 0.05). A threshold of 8,500 pg/mL gives Ang-2 a negative predictive value of 100% and positive predictive value of 42% in diagnosing recent arrhythmia. Ang-2 is elevated among adults with Fontan physiology. Ang-2 level is associated with active or recent arrhythmia, but was not found to be associated with PAVM.

The Role of Serum Procalcitonin in Predicting Bacterial Sepsis in Patients With Hypothyroidism.

CONTEXT: Serum levels of procalcitonin (PCT), a protein produced by the thyroid C cells under physiologic conditions, are high during sepsis. OBJECTIVE: To assess the test performance of serum PCT in predicting bacterial sepsis and septic shock in patients with hypothyroidism compared with those who have euthyroidism. DESIGN AND METHODS: This retrospective study evaluated patients with no history of thyroid dysfunction (euthyroid), primary hypothyroidism [medical hypothyroidism (MH)], and postsurgical hypothyroidism from total thyroidectomy (TT) identified from a prospectively maintained database who had PCT testing from 2005 to 2018. Quick Sequential Organ Failure Assessment score ≥ 2 or positive bacterial cultures identified bacterial sepsis, and a mean arterial pressure less than 65 mm Hg or a vasopressor requirement defined septic shock. Sensitivity and specificity of PCT for evaluation of bacterial sepsis and septic shock were measured. RESULTS: We identified 217 euthyroid patients, 197 patients with MH, and 84 patients with TT. Bacterial sepsis was found in 98 (45.2%), 92 (46.7%), and 36 (42.9%) of these patients, respectively (P > 0.05). Septic shock was identified in 13 (6.0%), 13 (6.6%), and 5 (6.0%) patients (P > 0.05), respectively. With use of a PCT cutoff of 0.5 µg/L for bacterial sepsis, the sensitivity was 59%, 61%, and 53% (P > 0.05) and specificity was 81%, 77%, and 81% (P > 0.05) for the diagnosis of bacterial sepsis in euthyroid, MH, and TT patients, respectively. With use of a PCT cutoff of 2.0 µg/L for septic shock, the sensitivity was 46%, 62%, and 63% (P > 0.05) and specificity was 86%, 82%, and 91% (P > 0.05) for the diagnosis of septic shock in these patients, respectively. CONCLUSIONS: Despite the thyroidal origin of PCT, hypothyroidism did not affect the diagnostic performance of serum PCT levels in predicting bacterial sepsis or septic shock.

Predictors of Outcomes After Thoracic Surgery in Orthotopic Liver Transplant Recipients With Pleural Disease.

Orthotopic liver transplant (OLT) recipients are at high risk for postoperative pulmonary complications. We aim to determine factors associated with morbidity and mortality in OLT recipients that required thoracic surgery for pleural space complications. A retrospective review was performed of 42 patients who underwent thoracic surgery after OLT between 2005 and 2015. Preoperative data and postoperative outcomes were reviewed. Time to mortality was summarized using Kaplan-Meier curves. Outcomes associated with 30-day morbidity and mortality as well as long-term mortality were analyzed with univariate analysis. Between 2005 and 2015, 1735 OLTs were performed at our institution. We identified 42 patients who required thoracic surgery. Of these 42 OLT recipients, 33 patients required thoracic surgery for pleural space complications. The median interval between OLT and thoracic surgery for pleural space complications was 5.7 months (interquartile range 2.2-14.1). The most common surgical indications were chronic pleural effusion (n = 12, 36.4%) and empyema (n = 10, 30.3%). The most common thoracic operations were decortication and empyema evacuation. The 30-day morbidity was 69.7%. Bilirubin and empyema were significantly associated with 30-day morbidity (odds ratio [OR] = 2.3, P = 0.023; OR = 16.3, P = 0.015). The 30-day, 1-year, and 5-year mortality rates were 15.2%, 57.6%, and 70.2%, respectively. Vasopressor requirement was significantly associated with 30-day mortality (OR = 10.2, P = 0.031). The development of pleural space complications requiring surgery in OLT recipients suggests a poor prognosis. Hyperbilirubinemia and pleural space infections were associated with high postoperative morbidity in OLT recipients requiring thoracic surgery for pleural space complications.

Sodium-glucose transporter 2 is a diagnostic and therapeutic target for early-stage lung adenocarcinoma.

The diagnostic definition of indeterminate lung nodules as malignant or benign poses a major challenge for clinicians. We discovered a potential marker, the sodium-dependent glucose transporter 2 (SGLT2), whose activity identified metabolically active lung premalignancy and early-stage lung adenocarcinoma (LADC). We found that SGLT2 is expressed early in lung tumorigenesis and is found specifically in premalignant lesions and well-differentiated adenocarcinomas. SGLT2 activity could be detected in vivo by positron emission tomography (PET) with the tracer methyl 4-deoxy-4-[18F] fluoro-alpha-d-glucopyranoside (Me4FDG), which specifically detects SGLT activity. Using a combination of immunohistochemistry and Me4FDG PET, we identified high expression and functional activity of SGLT2 in lung premalignancy and early-stage/low-grade LADC. Furthermore, selective targeting of SGLT2 with FDA-approved small-molecule inhibitors, the gliflozins, greatly reduced tumor growth and prolonged survival in autochthonous mouse models and patient-derived xenografts of LADC. Targeting SGLT2 in lung tumors may intercept lung cancer progression at early stages of development by pairing Me4FDG PET imaging with therapy using SGLT2 inhibitors.

Endothelial Regeneration of Large Vessels Is a Biphasic Process Driven by Local Cells with Distinct Proliferative Capacities.

The cellular and mechanistic bases underlying endothelial regeneration of adult large vessels have proven challenging to study. Using a reproducible in vivo aortic endothelial injury model, we characterized cellular dynamics underlying the regenerative process through a combination of multi-color lineage tracing, parabiosis, and single-cell transcriptomics. We found that regeneration is a biphasic process driven by distinct populations arising from differentiated endothelial cells. The majority of cells immediately adjacent to the injury site re-enter the cell cycle during the initial damage response, with a second phase driven by a highly proliferative subpopulation. Endothelial regeneration requires activation of stress response genes including Atf3, and aged aortas compromised in their reparative capacity express less Atf3. Deletion of Atf3 reduced endothelial proliferation and compromised the regeneration. These findings provide important insights into cellular dynamics and mechanisms that drive responses to large vessel injury.

A multi-step transcriptional cascade underlies vascular regeneration in vivo.

The molecular mechanisms underlying vascular regeneration and repair are largely unknown. To gain insight into this process, we developed a method of intima denudation, characterized the progression of endothelial healing, and performed transcriptome analysis over time. Next-generation RNA sequencing (RNAseq) provided a quantitative and unbiased gene expression profile during in vivo regeneration following denudation injury. Our data indicate that shortly after injury, cells immediately adjacent to the wound mount a robust and rapid response with upregulation of genes like Jun, Fos, Myc, as well as cell adhesion genes. This was quickly followed by a wave of proliferative genes. After completion of endothelial healing a vigorous array of extracellular matrix transcripts were upregulated. Gene ontology enrichment and protein network analysis were used to identify transcriptional profiles over time. Further data mining revealed four distinct stages of regeneration: shock, proliferation, acclimation, and maturation. The transcriptional signature of those stages provides insight into the regenerative machinery responsible for arterial repair under normal physiologic conditions.

Reproducible Arterial Denudation Injury by Infrarenal Abdominal Aortic Clamping in a Murine Model.

Percutaneous vascular interventions uniformly result in arterial denudation injuries that subsequently lead to thrombosis and restenosis. These complications can be attributed to impairments in re-endothelialization within the wound margins. Yet, the cellular and molecular mechanisms of re-endothelialization remain to be defined. While several animal models to study re-endothelialization after arterial denudation are available, few are performed in the mouse because of surgical limitations. This undermines the opportunity to exploit transgenic mouse lines and investigate the contribution of specific genes to the process of re-endothelialization. Here, we present a step-by-step protocol for creating a highly reproducible murine model of arterial denudation injury in the infrarenal abdominal aorta using external vascular clamping. Immunocytochemical staining of injured aortas for fibrinogen and ß-catenin demonstrate the exposure of a pro-thrombotic surface and the border of intact endothelium, respectively. The method presented here has the advantages of speed, excellent overall survival rate, and relative technical ease, creating a uniquely practical tool for imposing arterial denudation injury in transgenic mouse models. Using this method, investigators may elucidate the mechanisms of re-endothelialization under normal or pathological conditions.

Predicting the risk for acute type B aortic dissection in hypertensive patients using anatomic variables.

OBJECTIVES: This study sought to identify possible anatomic predictors of acute type B aortic dissection (AAD) in hypertensive patients using multidetector computed tomography angiography (CTA). BACKGROUND: Although hypertension remains one of the most significant risk factors for AAD development, it is unlikely to be the only risk factor for AAD. Few studies have assessed anatomical predictors of AAD development. METHODS: CTA of normotensive patients without AAD (group 1, n = 35), hypertensive patients without AAD (group 2, n = 37), and hypertensive patients with AAD (group 3, n = 37) were compared. The length, diameter, volume, and tortuosity of the aorta as well as arch vessel angulation were measured for each patient and normalized to group 1 averages. Stepwise logistic regression identified significant anatomical associations; the model was validated based on 1,000 bootstrapped samples. RESULTS: The demographics of the groups were similar. The length of the proximal and entire aorta, the diameters in the proximal ascending aorta and aortic arch, and the aortic volumes were all greater (p < 0.0001, p = 0.0064 for ascending aortic diameter) in group 3 than in groups 1 and 2, as was entire aortic tortuosity (p < 0.0001). An AAD risk model was developed based on aortic arch diameter, length from the aortic root to the iliac bifurcation, and angulation of the brachiocephalic artery origin from the aorta. The bootstrap estimate of the area under the receiver operating curve was 0.974. CONCLUSIONS: Enlargement of the ascending aorta and aortic arch and increased aortic tortuosity reflect an aortopathy which enhances the probability of AAD. A model based on 3 anatomical variables demonstrates significant associations with AAD: it may allow identification by aortic imaging of the hypertensive patient most at risk, and permit implementation of aggressive medical management and consideration of pre-emptive surgery to prevent dissection.