Formation of styrene maleic acid lipid nanoparticles (SMALPs) using SMA thin film on a substrate.

Despite the important role of membrane proteins in biological function and physiology, studying them remains challenging because of limited biomimetic systems for the protein to remain in its native membrane environment. Cryo electron microscopy (Cryo-EM) is emerging as a powerful tool for analyzing the structure of membrane proteins. However, Cryo-EM and other membrane protein analyses are better studied in a native lipid bilayer. Although traditional, mimetic systems have disadvantages that limit their use in the study of membrane proteins. As an alternative, styrene-maleic acid copolymers are used to form nanoparticles with POPC:POPG lipids. Traditional characterization of these styrene maleic acid lipid nanoparticles (SMALPs) includes dynamic light scattering (DLS), electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM). In this study a new method was developed that utilizes SMALPs using a styrene-maleic acid copolymer (SMA) thin film on a TEM grid, acting as a substrate. By directly adding POPC:POPG lipid vesicles to the SMA coated grid SMALPs can be formed, visualized, and characterized by TEM without the need to make them in solution prior to imaging. We envision these functionalized grids could aid in single particle specimen preparation, increasing the efficiency of structural biology and biophysical techniques such as Cryo-EM.

Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors.

OBJECTIVE: To characterize large adrenal tumors (≥4 cm in diameter) and to identify features associated with malignancy. PATIENTS AND METHODS: We investigated the clinical, biochemical, and imaging characteristics in a large retrospective single-center cohort of patients with adrenal tumors of 4 cm or more in diameter during the period of January 1, 2000, through December 31, 2014. RESULTS: Of 4085 patients with adrenal tumors, 705 (17%) had adrenal masses measuring 4 cm or more in diameter; of these, 373 (53%) were women, with a median age of 59 years (range, 18-91 years) and median tumor size of 5.2 cm (range, 4.0-24.4 cm). Underlying diagnoses were adrenocortical adenomas (n=216 [31%]), pheochromocytomas (n=158 [22%]), other benign adrenal tumors (n=116 [16%]), adrenocortical carcinomas (n=88 [13%]), and other malignant tumors (n=127 [18%]). Compared with benign tumors, malignant tumors were less frequently diagnosed incidentally (45.5% vs 86.7%), were larger (7 cm [range, 4-24.4 cm] vs 5 cm [range, 4-20 cm]), and had higher unenhanced computed tomographic (CT) attenuation (34.5 Hounsfield units [HU] [range, 14.1-75.5 HU] vs 11.5 HU [range, -110 to 71.3 HU]; P<.001). On multivariate analysis, older age at diagnosis, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were all found to be statistically significant predictors of malignancy. CONCLUSION: The prevalence of malignancy in patients with adrenal tumors of 4 cm or more in diameter was 31%. Older age, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were associated with an increased risk for malignancy. Clinical context should guide management in patients with adrenal tumors of 4 cm or more in diameter.

Preoperative Levels of Catecholamines and Metanephrines and Intraoperative Hemodynamics of Patients Undergoing Pheochromocytoma and Paraganglioma Resection.

OBJECTIVE: To determine whether, despite pharmacologic adrenergic receptor blockade, higher preoperative levels of catecholamines and metanephrines (adrenergic activity) are associated with increased intraoperative complications. MATERIALS AND METHODS: Records of patients undergoing paraganglioma and pheochromocytoma (PGL-PCC) resection from January 1, 2000, to June 30, 2015, were reviewed for preoperative levels of adrenergic activity, intraoperative variability in blood pressure and heart rate (range), and postoperative outcomes (hypotension requiring treatment). Patients were categorized by maximum preoperative adrenergic activity by greater degree of abnormality, categorized as normal (≤100%) or 101%-200%, 201%-500%, 501%-1000%, and ≥1001% of upper limit of normal. RESULTS: In total, 258 patients underwent intrathoracic or intra-abdominal PGL-PCC resection, of whom 240 received pretreatment with nonselective α1,2-blockers and 7 received pretreatment with selective α1-blockers. Intraoperative hemodynamic variability was greater with higher preoperative levels of adrenergic activity (P <.001). However, substantial variability was observed even with adrenergic activity levels within the normal range: systolic blood pressure (median [interquartile range], 75 [63-83] mm Hg) and heart rate (34 [26-43] beats per minute). Among patients with preoperative levels of adrenergic activity ≤500% vs ≥501% of the upper limit of normal, higher levels were associated with greater likelihood of postoperative diagnosis of volume overload (8% vs 2%, P = .04) and greater requirement for vasopressor infusions for hypotension (5% vs 1%, P = .01). CONCLUSION: Substantial intraoperative hemodynamic instability was encountered in patients with PGL-PCC resection, regardless of preoperative hormonal activity level; therefore, universal preoperative adrenergic receptor blockade should be recommended. Postoperative hypotension was rare and more prevalent in those with higher preoperative hormonal activity.