New insights on the binding of butyl-paraben to trypsin: experimental and computational approaches.

Butyl-paraben (BP) is one of the most widely used preservatives in numerous foodstuffs, skin care products, and a variety of drugs, and trypsin is the main digestive enzyme, the research on the binding between the two is essential for human health. In the present paper, the effect of BP on trypsin has been explored using experimental and computational techniques to evaluate BP toxicity at the protein level. The obtained results from molecular docking and kinetic assay revealed BP was embedded in the hydrophobic cavity-S1 binding pocket of the enzyme to inhibit its activity by a competitive model. Intrinsic fluorescence of trypsin after interaction with BP revealed the static mode of quenching. FRET indicated that the distance of the enzyme to BP is 1.89 nm with high energy efficiency. Thermodynamic results proved that BP spontaneously bound to trypsin in an enthalpy-driven manner, the van der Waals interactions and H-bonds serving as the predominant forces in binding processes. CD spectroscopy and molecular dynamics (MD) simulation revealed that the trypsin structure transformed from the ß-Sheet structure to the unordered Coil structure upon interacting with BP. Resonance light scattering (RLS), synchronous fluorescence, and three-dimensional (3 D) spectroscopies further supported the alteration in the conformation of trypsin. Differential scanning calorimetry (DSC) showed that trypsin was somewhat destabilized in the presence of BP. Accordingly, all of the experimental data were confirmed by MD simulation.Communicated by Ramaswamy H. Sarma.

High-resolution computed tomography finding in 552 patients with symptomatic COVID-19: first report from north of Iran.

PURPOSE: Due to the emergence of the new coronavirus 2019 and the lack of sufficient information about infected patients, this study was conducted to investigate the chest high-resolution computed tomography (HRCT) findings of patients infected with the new coronavirus 2019. METHODS: This cross-sectional study was performed on COVID-19 patients referred to Medical Imaging Centers of Sari, Mazandaran, Iran, on March 2020 for computed tomography (CT) scan. Symptomatic patients were referred to the Medical Imaging Center for diagnosis confirmation through CT scan. In addition to age and sex, HRCT findings were collected from the picture archiving and communication system (PACS) for further evaluations. RESULTS: Out of 552 patients with mean age of 51.2 ± 14.8 years, the male/female ratio was 1.38 to 1. The most common expressive findings in patients were ground-glass opacity (GGO) (87.3%), peripheral distribution (82.4%), and posterior distribution (81.5%). The most conflicting findings in patients were pleural effusion (7.6%), peribronchovascular distribution (7.6%), and lymphadenopathy (5.1%). The peripheral distribution (p = 0.034), round opacities (p = 0.02), single lobe (p = 0.003), and pleural effusion (p = 0.037) were significant in people under and over 50 years of age. CONCLUSION: In summary, the present study indicated that in addition to GGO, peripheral distribution findings could be a vital diagnostic choice in COVID-19 patients.

Diagnostic Accuracy of a Three-point Compression Ultrasonography Performed by Emergency Medicine Resident for the Diagnosis of Deep Vein Thrombosis: a Prospective Diagnostic Study.

INTRODUCTION: Deep vein thrombosis (DVT) is a common cause of admission to the emergency departments (ED). Doppler ultrasonography of the entire lower limb is the first-line imaging modality. But most EDs do not access to full-time radiologists which can lead to delayed diagnosis. AIM: The aim of this study was to evaluate the diagnostic accuracy of three-point compression ultrasonography performed by emergency medicine resident for diagnosis of DVT. METHODS: This prospective diagnostic study was carried out at Imam Khomeini Hospital in Sari from March 2018 to November 2018. For all patients with suspected lower extremity DVT, first bedside 3-point compression ultrasound were performed by a third year emergency medicine resident at ED. Then Doppler ultrasonography were performed by a radiologist in the radiology department, as a reference test. Sensitivity, specificity, and positive predictive value of the three-point compression ultrasound performed by emergency medicine resident was calculated. RESULTS: Of the 72 patients enrolled in our study, 50% of the patients were male, with an average age of 36±19 years. The mean of patient admission time to perform ultrasonography by an emergency medicine resident and radiologist were 14.05±19 and 216±140.1 minutes, respectively. The two groups had a statistically significant difference (P<0.0001). In ultrasonography performed by emergency medicine resident and doper ultrasonography by radiologist, 91.67% and 36.1% of patients were diagnosed with DVT, respectively. Although the ultrasonography performed by emergency medicine resident has a relatively low sensitivity (53.8%), it has a good specificity (85.7%). The positive and negative predictive value was 70 and 75%, respectively. CONCLUSION: Although the results of this study indicate insufficient sensitivity of bedside three-point compression ultrasound performed by emergency medicine resident in diagnosis of lower limb DVT, the specificity, positive and negative predictive values and positive likelihood ratio were almost appropriate.