Electronic cigarettes use and perception amongst medical students: a cross sectional survey from Sindh, Pakistan

Objective: The manufacturers of electronic cigarettes (e-cigarettes) are actively marketing their product through electronic and social media. Undergraduate medical students are expected to have better knowledge and awareness as they directly interact with patients in their training, The purpose of this study is therefore, to determine knowledge, use and perception regarding e-cigarettes among medical students from Sindh, Pakistan. Results: A cross-sectional study was conducted between 1st July and 30th September 2016 at five different medical colleges situated in the second largest province of Sindh, Pakistan. The data was collected through a structured, self-administered questionnaire. Of the 500 students, the mean age was 21.5 ± 1.7 years and 58% were females. Over (65.6%) students were aware of e-cigarettes, 31 (6.2%) reported having used e-cigarettes, of whom 6 (1.2%) self-reported daily use. Users of conventional tobacco products were significantly more likely to have heard of e-cigarettes (87.6% vs 51.6%, p \u3c 0.001) and having used them (13.9% vs 1.3%, p \u3c 0.001). On multivariable logistic regression analysis we found a strong association of e-cigarette use with consumption of conventional cigarettes [OR: 10.6, 95% CI 3.6-30.8, p \u3c 0.001], use of smokeless tobacco products [OR: 7.9, 95% CI 2.7-23.4, p \u3c 0.001] however a weak association was observed for Shisha use [OR: 3.05, 95% CI 0.9-9.6, p = 0.05]

Characterization of inhibitory molecular interaction between PBD and KD of Plk1.

<p>Cyan blue meshy ribbon represents the KD with interacting residues in cyan stick form, while PBD is represented in pink meshy ribbon with interacting residues in pink stick. Hydrogen bonds are represented by black dotted lines with bond distances in angstrom.</p

Identification of Potential Plk1 Targets in a Cell-Cycle Specific Proteome through Structural Dynamics of Kinase and Polo Box-Mediated Interactions

<div><p>Polo like kinase 1 (Plk1) is a key player in orchestrating the wide variety of cell-cycle events ranging from centrosome maturation, mitotic entry, checkpoint recovery, transcriptional control, spindle assembly, mitotic progression, cytokinesis and DNA damage checkpoints recovery. Due to its versatile nature, Plk1 is considered an imperative regulator to tightly control the diverse aspects of the cell cycle network. Interactions among Plk1 polo box domain (PBD) and its putative binding proteins are crucial for the activation of Plk1 kinase domain (KD). To date, only a few substrate candidates have been characterized through the inclusion of both polo box and kinase domain-mediated interactions. Thus it became compelling to explore precise and specific Plk1 substrates through reassessment and extension of the structure-function paradigm. To narrow this apparently wide gap in knowledge, here we employed a thorough sequence search of Plk1 phosphorylation signature containing proteins and explored their structure-based features like conceptual PBD-binding capabilities and subsequent recruitment of KD directed phosphorylation to dissect novel targets of Plk1. Collectively, we identified 4,521 phosphodependent proteins sharing similarity to the consensus phosphorylation and PBD recognition motifs. Subsequent application of filters including similarity index, Gene Ontology enrichment and protein localization resulted in stringent pre-filtering of irrelevant candidates and isolated unique targets with well-defined roles in cell-cycle machinery and carcinogenesis. These candidates were further refined structurally using molecular docking and dynamic simulation assays. Overall, our screening approach enables the identification of several undefined cell-cycle associated functions of Plk1 by uncovering novel phosphorylation targets.</p></div

Schematic illustration of strategy.

<p>(a) Plk1 candidates substrates were selected on the basis of series of filters applied to human proteome including, presence of Plk1 specific phosphorylation motif at sequence level, minimum 80% identity, clustering on the basis of biological process, cellular localization and molecular function, presence of PBD recognition motif, common cell-cycle localization and role in cancer. (b) Scheme depicting different structure-based techniques used for the validation of putative hits obtained from sequence-based approaches.</p

Multiple scoring functions of selected substrates with Plk1.

<p>Multiple scoring functions of selected substrates with Plk1.</p

Conformational switches of Plk1 structure upon substrate binding.

<p>NEK5 (white), NUP35 (pink), GSG2 (blue) and SMARCAD1 (yellow). (I) Helical region is variable in NEK5, NUP35 and SMARCAD1. (II) Specific binding orientation of active site residues in different complexes. (III) Extension of β-strand at two regions, Ile553-Glu555 in Nup53, GSG2 and SMARCAD1 complexes and Leu435-Phe436 in NEK5, NUP35 complexes. (IV) Changes at linker region between two PBD domains of Plk1. (V) Three residues (Phe516-Arg518) extension of β strand in GSG2 complex.</p

Multiple sequence alignment (MSA), secondary and tertiary structures of four selected Plk1 specific substrates.

<p>(a) SMARCAD1, (b) GSG2, (c) NUP35, (d) NEK5, (e) KIF23 and (f) CEP170. MSA illustrates the conservation pattern of predicted PBD recognition and kinase phosphorylation motifs across close homologues of selected proteins (a–d). Secondary structure for each substrate was predicted by JPred as shown below the alignments Tertiary structures of (a–f) substrates are shown in cornflower blue ribbon-form, phosphorylation motifs are shown in yellow, PBD recognition motifs are shown in pink.</p