BackgroundThe intubation difficulty scale (IDS) has been used as a validated difficulty score to define difficult intubation (DI). The purpose of this study is to identify airway assessment factors and total airway score (TAS) for predicting DI defined by the IDS.MethodsThere were 305 ASA physical status 1-2 patients, aged 19-70 years, who underwent elective surgery with endotracheal intubation. During the pre-anesthetic visit, we evaluated patients by 7 preoperative airway assessment factors, including the following: Mallampati classification, thyromental distance, head & neck movement, body mass index (BMI), buck teeth, inter-incisor gap, and upper lip bite test (ULBT). After endotracheal intubation, patients were divided into 2 groups based on their IDS score estimated with 7 variables: normal (IDS < 5) and DI (IDS ≥ 5) groups. The incidence of TAS (> 6) and high score of each airway assessment factor was compared in two groups: odds ratio, confidence interval (CI) of 95%, with a significant P value ≤ 0.05.ResultsThe odds ratio of TAS (> 6), ULBT (class III), head & neck movement (< 90°), inter-incisor gap (< 4 cm), BMI (≥ 25 kg/m2) and Mallampati classification (≥ class III) were respectively 13.57 (95% CI = 2.99-61.54, P < 0.05), 12.48 (95% CI = 2.50-62.21, P < 0.05), 3.11 (95% CI = 0.87-11.13), 2.32 (95% CI = 0.75-7.19), 2.22 (95% CI = 0.81-6.06), and 1.22 (95% CI = 0.38-3.89).ConclusionsWe suggest that TAS (> 6) and ULBT (class III) are the most useful factors predicting DI.

Integrin trafficking, including internalization, recycling, and lysosomal degradation, is crucial for the regulation of cellular functions. Exosomes, nano-sized extracellular vesicles, are believed to play important roles in intercellular communications. This study demonstrates that exosomes released from human macrophages negatively regulate endothelial cell migration through control of integrin trafficking. Macrophage-derived exosomes promote internalization of integrin β1 in primary HUVECs. The internalized integrin β1 persistently accumulates in the perinuclear region and is not recycled back to the plasma membrane. Experimental results indicate that macrophage-derived exosomes stimulate trafficking of internalized integrin β1 to lysosomal compartments with a corresponding decrease in the integrin destined for recycling endosomes, resulting in proteolytic degradation of the integrin. Moreover, ubiquitination of HUVEC integrin β1 is enhanced by the exosomes, and exosome-mediated integrin degradation is blocked by bafilomycin A, a lysosomal degradation inhibitor. Macrophage-derived exosomes were also shown to effectively suppress collagen-induced activation of the mitogenactivated protein kinase/extracellular signal-regulated kinase signaling pathway and HUVEC migration, which are both dependent on integrin β1. These observations provide new insight into the functional significance of exosomes in the regulation of integrin trafficking. Keywords: Endothelial cell migration r Exosomes r Integrin trafficking r MacrophagesAdditional supporting information may be found in the online version of this article at the publisher's web-site IntroductionIntegrin, a heterodimeric transmembrane receptor composed of α-and β-subunits, has a fundamental role in communication between cells and the extracellular matrix [1,2]. Recent studies have shown that trafficking of integrin is a crucial step in this communication [3][4][5]. Integrin is regularly internalized via the endocytosis pathway and internalized integrin is recycled back to the plasma membrane [3,4]. Internalized integrin β1, the most widely expressed integrin subunit, accumulates in the perinuclear Correspondence: Dr. Doo-Sik Kim e-mail: dskim@yonsei.ac.kr region of cells and is returned to the plasma membrane through RAB11-positive recycling endosomes [3]. The recycling process rearranges the distribution of integrins on the cell surface and controls the direction of cell migration [3]. Ubiquitination of integrin acts as a signal to trigger trafficking of internalized integrin to the lysosomal degradation compartment [5,6]. The degradation process is important for controlling the proper expression level of integrin on the cell surface, by which cell-matrix association and cell migration are tightly regulated [5,7].Integrin is a key regulator of cellular functions associated with vascular processes [8,9]. Endothelial cell migration and leukocyte recruitment during inflammation are tightly controlled by integrin functions. The expression and activation of integrins C...

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