bluuebunny/crossref_metadata_2025_split huggingface dataset:
MS2 Lysis of Escherichia coli Depends on Host Chaperone DnaJ
Authors: Chamakura Karthik R. , Tran Jennifer S. , Young Ry 
Published: April 2017

ABSTRACT

The L protein of the single-stranded RNA phage MS2 causes lysis of
Escherichia coli
without inducing bacteriolytic activity or inhibiting net peptidoglycan (PG) synthesis. To find host genes required for L-mediated lysis, spontaneous Ill (
i
nsensitivity to
L
l
ysis) mutants were selected as survivors of L expression and shown to have a missense change of the highly conserved proline (P330Q) in the C-terminal domain of DnaJ. In the
dnaJ
P330Q
mutant host, L-mediated lysis is completely blocked at 30°C without affecting the intracellular levels of L. At higher temperatures (37°C and 42°C), both lysis and L accumulation are delayed. The lysis block at 30°C in the
dnaJ
P330Q
mutant was recessive and could be suppressed by

L

o
vercomes

d

na

J

(

L
odj

) alleles selected for restoration of lysis. All three

L
odj

alleles lack the highly basic N-terminal half of the lysis protein and cause lysis ∼20 min earlier than full-length L. DnaJ was found to form a complex with full-length L. This complex was abrogated by the P330Q mutation and was absent with the L
odj
truncations. These results suggest that, in the absence of interaction with DnaJ, the N-terminal domain of L interferes with its ability to bind to its unknown target. The lysis retardation and DnaJ chaperone dependency conferred by the nonessential, highly basic N-terminal domain of L resembles the SlyD chaperone dependency conferred by the highly basic C-terminal domain of the E lysis protein of ϕX174, suggesting a common theme where single-gene lysis can be modulated by host factors influenced by physiological conditions.

IMPORTANCE
Small single-stranded nucleic acid lytic phages (
Microviridae
and
Leviviridae
) lyse their host by expressing a single “protein antibiotic.” The protein antibiotics from two out of three prototypic small lytic viruses have been shown to inhibit two different steps in the conserved PG biosynthesis pathway. However, the molecular basis of lysis caused by L, the lysis protein of the third prototypic virus, MS2, is unknown. The significance of our research lies in the identification of DnaJ as a chaperone in the MS2 L lysis pathway and the identification of the minimal lytic domain of MS2 L. Additionally, our research highlights the importance of the highly conserved P330 residue in the C-terminal domain of DnaJ for specific protein interactions.
Biochemical and Genetic Analysis of the Chlamydia GroEL Chaperonins
Authors: Illingworth Melissa , Hooppaw Anna J. , Ruan Lu , Fisher Derek J. , Chen Lingling 
Published: April 2017

ABSTRACT

Chaperonins are essential for cellular growth under normal and stressful conditions and consequently represent one of the most conserved and ancient protein classes. The paradigm
Escherichia coli
chaperonin, EcGroEL, and its cochaperonin, EcGroES, assist in the folding of proteins via an ATP-dependent mechanism. In addition to the presence of
groEL
and
groES
homologs,
groEL
paralogs are found in many bacteria, including pathogens, and have evolved poorly understood species-specific functions.
Chlamydia
spp., which are obligate intracellular bacteria, have reduced genomes that nonetheless contain three
groEL
genes,
Chlamydia groEL
(
ChgroEL
),
ChgroEL2
, and
ChgroEL3
. We hypothesized that ChGroEL is the bona fide chaperonin and that the paralogs perform novel
Chlamydia
-specific functions. To test our hypothesis, we investigated the biochemical properties of ChGroEL and its cochaperonin, ChGroES, and queried the
in vivo
essentiality of the three
ChgroEL
genes through targeted mutagenesis in
Chlamydia trachomatis
. ChGroEL hydrolyzed ATP at a rate 25% of that of EcGroEL and bound with high affinity to ChGroES, and the ChGroEL-ChGroES complex could refold malate dehydrogenase (MDH). The chlamydial ChGroEL was selective for its cognate cochaperonin, ChGroES, while EcGroEL could function with both EcGroES and ChGroES. A P35T ChGroES mutant (ChGroESP35T) reduced ChGroEL-ChGroES interactions and MDH folding activities but was tolerated by EcGroEL. Both ChGroEL-ChGroES and EcGroEL-ChGroESP35T could complement an EcGroEL-EcGroES mutant. Finally, we successfully inactivated both paralogs but not
ChgroEL
, leading to minor growth defects in cell culture that were not exacerbated by heat stress. Collectively, our results support novel functions for the paralogs and solidify ChGroEL as a bona fide chaperonin that is biochemically distinct from EcGroEL.

IMPORTANCE
Chlamydia
is an important cause of human diseases, including pneumonia, sexually transmitted infections, and trachoma. The chlamydial chaperonin ChGroEL and chaperonin paralog ChGroEL2 have been associated with survival under stress conditions, and ChGroEL is linked with immunopathology elicited by chlamydial infections. However, their exact roles in bacterial survival and disease remain unclear. Our results further substantiate the hypotheses that ChGroEL is the primary chlamydial chaperonin and that the paralogs play specialized roles during infection. Furthermore, ChGroEL and the mitochondrial GroEL only functioned with their cochaperonin, in contrast to the promiscuous nature of GroEL from
E. coli
and
Helicobacter pylori
, which might indicate a divergent evolution of GroEL during the transition from a free-living organism to an obligate intracellular lifestyle.
Diverse C-Terminal Sequences Involved in Flavobacterium johnsoniae Protein Secretion
Authors: Kulkarni Surashree S. , Zhu Yongtao , Brendel Colton J. , McBride Mark J. 
Published: April 2017

ABSTRACT

Flavobacterium
johnsoniae
and many related bacteria secrete proteins across the outer membrane using the type IX secretion system (T9SS). Proteins secreted by T9SSs have amino-terminal signal peptides for export across the cytoplasmic membrane by the Sec system and carboxy-terminal domains (CTDs) targeting them for secretion across the outer membrane by the T9SS. Most but not all T9SS CTDs belong to the family TIGR04183 (type A CTDs). We functionally characterized diverse CTDs for secretion by the
F. johnsoniae
T9SS. Attachment of the CTDs from
F. johnsoniae
RemA, AmyB, and ChiA to the foreign superfolder green fluorescent protein (sfGFP) that had a signal peptide at the amino terminus resulted in secretion across the outer membrane. In each case, approximately 80 to 100 amino acids from the extreme carboxy termini were needed for efficient secretion. Several type A CTDs from distantly related members of the phylum
Bacteroidetes
functioned in
F. johnsoniae
, supporting the secretion of sfGFP by the
F. johnsoniae
T9SS.
F. johnsoniae
SprB requires the T9SS for secretion but lacks a type A CTD. It has a conserved C-terminal domain belonging to the family TIGR04131, which we refer to as a type B CTD. The CTD of SprB was required for its secretion, but attachment of C-terminal regions of SprB of up to 1,182 amino acids to sfGFP failed to result in secretion. Additional features outside the C-terminal region of SprB may be required for its secretion.

IMPORTANCE
Type IX protein secretion systems (T9SSs) are common in but limited to members of the phylum
Bacteroidetes
. Most proteins that are secreted by T9SSs have conserved carboxy-terminal domains that belong to the protein domain family TIGR04183 (type A CTDs) or TIGR04131 (type B CTDs). Here, we identify features of T9SS CTDs of
F. johnsoniae
that are required for protein secretion and demonstrate that type A CTDs from distantly related members of the phylum function with the
F. johnsoniae
T9SS to secrete the foreign protein sfGFP. In contrast, type B CTDs failed to target sfGFP for secretion, suggesting a more complex association with the T9SS.
The Eyesi simulator in training ophthalmology residents: results of a pilot study on self-efficacy, motivation and performance
Authors: Wisse Robert PL , Coster Tessa , Van der Schaaf Marieke , Ten Cate Olle 
Published: April 2017

PurposeTo describe ophthalmology residents’ motivation and self-efficacy during cataract surgery training and to assess the relationship of self-efficacy and motivation on both simulator (Eyesi) and real-life surgical performance.MethodsProspective cohort study using a within-subject design. Eight residents were asked to fill out questionnaires on self-efficacy and motivation towards the Eyesi simulator and real-life cataract surgery at three different moments. Simulator performance was derived from the instrument’s output. Patient charts were reviewed to assess real-life surgical performance.ResultsComparative analysis, using a paired sampled t-test, showed a significant increase in self-efficacy towards real-life cataract surgery after completing the cataract training on the simulator (p=0.005). Furthermore, we found a significant correlation between total tasks to complete the cataract training and self-efficacy scored after working with the simulator (p=0.038). Motivation towards the simulator remained stable over time and seemed not to be influenced by simulator or real-life performance.ConclusionsWe found evidence that performance on the simulator correlated with residents’ self-efficacy scored after the simulator training, supporting the theory that self-efficacy is determined by prior performance. Self-efficacy seemed inversely related to the ease of completion of a task: delivery of a greater effort leads to more satisfaction and a higher perceived self-efficacy towards this particular task. Future studies should include more subjects to provide a more accurate insight in the role of self-efficacy and motivation in training complex surgical skills.
Residents’ use of mobile technologies: three challenges for graduate medical education
Authors: MacLeod Anna , Fournier Cathy 
Published: April 2017

IntroductionThe practice of medicine involves, among other things, managing ambiguity, interpreting context and making decisions in the face of uncertainty. These uncertainties, amplified for learners, can be negotiated in a variety of ways; however, the promise, efficiency and availability of mobile technologies and clinical decision supports make these tools an appealing way to manage ambiguity.Mobile technologies are becoming increasingly prevalent in medical education and in the practice of medicine. Because of this, we explored how the use of mobile technologies is influencing residents’ experiences of graduate medical education.MethodsWe conducted an 18-month qualitative investigation to explore this issue. Our research was conceptually and theoretically framed in sociomaterial studies of professional learning. Specifically, our methods included logging of technology use and related reflexive writing by residents (n=10), interviews with residents (n=12) and interviews with faculty (n=6).ResultsWe identified three challenges for graduate medical education related to mobile technology use: (1) efficiency versus critical thinking; (2) patient context versus evidence-based medicine and (3) home/work-life balance.DiscussionIn this digital age, decontextualised knowledge is readily available. Our data indicate that rather than access to accurate knowledge, the more pressing challenge for medical educators is managing how, when and why learners choose to access that information.
Analysis of a novel double driving signal line and driving electrodes separated RF MEMS switch
Authors: Chen Zhiqiang , Tian Wenchao , Zhang Xiaotong 
Published: April 2017

A novel double driving signal line and driving electrodes separated radio frequency (RF) micro-electromechanical system (MEMS) switch was proposed in this paper to overcome the problems of the high actuation voltage, small displacement, and long pull-down time of the RF MEMS switches. Dynamic equations of the micro beam were built based on the small deflection theory. Dynamic behaviors of the proposed RF MEMS switch were analyzed and calculated by the variable separation method. The effects of different driving voltages, structure parameters and materials on the RF MEMS switch performance were discussed in detail. The simulation results presented that the proposed RF MEMS switch had an actuation voltage of 26 V, a pull-down time of 31.5 [Formula: see text] and an actuation displacement of 3 [Formula: see text]. The results also showed that the pull-down time of micro beam increased as the dielectric layer thickness increased. When the beam thickness was higher than 1.1 [Formula: see text], the switch could not pull down anymore. Additionally, the switch had a lowest pull down time when Al was used as micro beam material, compared to Au, Si, and SiC. The COMSOL Multiphysics finite element analysis was carried out to validate the MATLAB simulation results, and the comparison results were basically consistent with the MATLAB simulation results. Besides, the proposed switch had an insertion loss of −0.2 dB on up-state and isolation of more than −20 dB on down-state at 60 GHz derived from the electromagnetic simulation results. The actuation voltage, pull-down time, actuation displacement, and electromagnetic performances of the proposed RF MEMS switch were compared to some other switches, which were better than some existing switches.
Acquired MET Y1248H and D1246N Mutations Mediate Resistance to MET Inhibitors in Non–Small Cell Lung Cancer
Authors: Li Anna , Yang Jin-ji , Zhang Xu-chao , Zhang Zhou , Su Jian , Gou Lan-ying , Bai Yu , Zhou Qing , Yang Zhenfan , Han-Zhang Han , Zhong Wen-Zhao , Chuai Shannon , Zhang Qi , Xie Zhi , Gao Hongfei , Chen Huajun , Wang Zhen , Wang Zheng , Yang Xue-ning , Wang Bin-chao , Gan Bin , Chen Zhi-hong , Jiang Ben-yuan , Wu Si-pei , Liu Si-yang , Xu Chong-rui , Wu Yi-long 
Published: April 2017

Abstract
Purpose: MET amplification, responsible for 20% of acquired resistance to EGFR tyrosine kinase inhibitor (TKI) in patients with advanced non–small cell lung cancer (NSCLC), presents an attractive target. Numerous studies have conferred susceptibility of MET mutations and focal amplification to targeted MET-TKIs. However, the mechanism underlying MET-TKIs–induced resistance remains elusive.
Experimental Design: We conducted a cohort of 12 patients with advanced NSCLC who developed resistance to a combinatorial therapy consisting of gefitinib and a type I MET-TKI. We performed capture-based targeted ultra-deep sequencing on serial tumor biopsies and plasmas ctDNA samples to detect and quantify genetic alterations.
Results: We identified 2 newly acquired MET mutations, Y1248H and D1246N, in 2 patients and further confirmed their resistance against type I MET-TKIs in silco, in vitro, and in vivo. Interestingly, NIH3T3 cells harboring either mutation exhibited responses to type II MET-TKIs, suggesting sequential use of MET-TKIs may offer a more durable response. In addition, we also discovered that EGFR amplification may act as an alternative MET-TKI resistance mechanism.
Conclusions: Our study provides insight into the diversity of mechanisms underlying MET-TKI–induced resistance and highlights the potential of sequential use of MET-TKIs. Clin Cancer Res; 23(16); 4929–37. ©2017 AACR.
A Novel Galectin-1 Inhibitor Discovered through One-Bead Two-Compound Library Potentiates the Antitumor Effects of Paclitaxel in vivo
Authors: Shih Tsung-Chieh , Liu Ruiwu , Fung Gabriel , Bhardwaj Gaurav , Ghosh Paramita M. , Lam Kit S. 
Published: April 2017

Abstract
Through the one-bead two-compound (OB2C) ultra–high-throughput screening method, we discovered a new small-molecule compound LLS2 that can kill a variety of cancer cells. Pull-down assay and LC/MS-MS indicated that galectin-1 is the target protein of LLS2. Galectin-1 is known to be involved in the regulation of proliferation, apoptosis, cell cycle, and angiogenesis. Binding of LLS2 to galectin-1 decreased membrane-associated H-Ras and K-Ras and contributed to the suppression of pErk pathway. Importantly, combination of LLS2 with paclitaxel (a very important clinical chemotherapeutic agent) was found to exhibit synergistic activity against several human cancer cell lines (ovarian cancer, pancreatic cancer, and breast cancer cells) in vitro. Furthermore, in vivo therapeutic study indicated that combination treatment with paclitaxel and LLS2 significantly inhibits the growth of ovarian cancer xenografts in athymic mice. Our results presented here indicate that the OB2C combinatorial technology is a highly efficient drug screening platform, and LLS2 discovered through this method can be further optimized for anticancer drug development. Mol Cancer Ther; 16(7); 1212–23. ©2017 AACR.
Novel Indole-based Tambjamine-Analogues Induce Apoptotic Lung Cancer Cell Death through p38 Mitogen-Activated Protein Kinase Activation
Authors: Manuel-Manresa Pilar , Korrodi-Gregório Luís , Hernando Elsa , Villanueva Alberto , Martínez-García David , Rodilla Ananda M. , Ramos Ricard , Fardilha Margarida , Moya Juan , Quesada Roberto , Soto-Cerrato Vanessa , Pérez-Tomás Ricardo 
Published: April 2017

AbstractLung cancer has become the leading killer cancer worldwide, due to late diagnosis and lack of efficient anticancer drugs. We have recently described novel natural-derived tambjamine analogues that are potent anion transporters capable of disrupting cellular ion balance, inducing acidification of the cytosol and hyperpolarization of cellular plasma membranes. Although these tambjamine analogues were able to compromise cell survival, their molecular mechanism of action remains largely unknown. Herein we characterize the molecular cell responses induced by highly active indole-based tambjamine analogues treatment in lung cancer cells. Expression changes produced after compounds treatment comprised genes related to apoptosis, cell cycle, growth factors and its receptors, protein kinases and topoisomerases, among others. Dysregulation of BCL2 and BIRC5/survivin genes suggested the apoptotic pathway as the induced molecular cell death mechanism. In fact, activation of several proapoptotic markers (caspase-9, caspase-3, and PARP) and reversion of the cytotoxic effect upon treatment with an apoptosis inhibitor (Z-VAD-FMK) were observed. Moreover, members of the Bcl-2 protein family suffered changes after tambjamine analogues treatment, with a concomitant protein decrease towards the prosurvival members. Besides this, it was observed cellular accumulation of ROS upon compound treatment and an activation of the stress-kinase p38 MAPK route that, when inhibited, reverted the cytotoxic effect of the tambjamine analogues. Finally, a significant therapeutic effect of these compounds was observed in subcutaneous and orthotopic lung cancer mice models. Taken together, these results shed light on the mechanism of action of novel cytotoxic anionophores and demonstrate the therapeutic effects against lung cancer. Mol Cancer Ther; 16(7); 1224–35. ©2017 AACR.
Pyriform Aperture Stenosis: A Novel Approach to Stenting
Authors: Smith Aaron , Kull Amanda , Thottam Prasad , Sheyn Anthony 
Published: April 2017

Objectives: Congenital nasal pyriform aperture stenosis (CNPAS) is one of several causes of neonatal respiratory distress. Congenital nasal pyriform aperture stenosis can be diagnosed by clinical presentation and evaluated by computed tomography for degree of stenosis. Surgical management of indicated cases involves drillout of pyriform aperture with placement of stents. The following case presents a novel approach to choice of stent in these patients. Case Presentation: We report the case of an infant diagnosed with CNPAS who underwent surgical correction at 9 days of life, with placement of mometasone fuorate stents. Discussion: Although relatively uncommon, CNPAS is a type of airway obstruction that causes cyclic cyanosis and failure to thrive in affected infants. If uncorrected medically, surgical interventions can successfully restore patency of the nasal cavity. While traditional stents can result in undesired complications, the use of mometasone fuorate stents presents an alternative without the typically associated risks. Conclusion: The use of mometasone fuorate stents may be a helpful option for otolaryngologists looking for the potential to avoid restenosis, plugging, and nasal alar necrosis in patients undergoing surgical treatment of CNPAS.
Preoperative Drug Induced Sleep Endoscopy Improves the Surgical Approach to Treatment of Obstructive Sleep Apnea
Authors: Huntley Colin , Chou David , Doghramji Karl , Boon Maurits 
Published: April 2017

Objective: Drug induced sleep endoscopy (DISE) allows for preoperative evaluation of the specific site and character of upper airway obstruction in obstructive sleep apnea (OSA). We aim to assess the impact DISE has on customizing the surgical plan and evaluate its role in surgical success. Methods: We retrospectively reviewed patients undergoing surgery for OSA. We compared those patients undergoing preoperative DISE to those that did not to assess procedures performed and surgical outcomes. Results: We found 87 patients undergoing surgery for OSA who had postoperative polysomnogram results. Of the group undergoing preoperative DISE, 8% had multilevel surgery. This compared to 59.5% in those not undergoing DISE ( p = .0004). The success rate of patients who had preoperative DISE was 86% compared to 51.4% in those who did not have preoperative DISE ( p < .001). We found no difference in age, gender, preoperative apnea-hypopnea index (AHI), oxygen nadir, Epworth sleepiness scale score (ESS), body mass index (BMI) and postoperative oxygen nadir, ESS, or BMI in the DISE and no DISE cohorts. Conclusion: The addition of DISE to our preoperative workup has contributed to a decreased rate of multilevel surgery and increased rate of surgical success through identification of the individual patient’s OSA architecture and customization of the surgical plan.
Coherent Raman Scattering Microscopy for Evaluation of Head and Neck Carcinoma
Authors: Hoesli Rebecca C. , Orringer Daniel A. , McHugh Jonathan B. , Spector Matthew E. 
Published: April 2017

ObjectiveWe aim to describe a novel, label‐free, real‐time imaging technique, coherent Raman scattering (CRS) microscopy, for histopathological evaluation of head and neck cancer. We evaluated the ability of CRS microscopy to delineate between tumor and nonneoplastic tissue in tissue samples from patients with head and neck cancer.Study DesignProspective case series.SettingTertiary care medical center.Subjects and MethodsPatients eligible were surgical candidates with biopsy‐proven, previously untreated head and neck carcinoma and were consented preoperatively for participation in this study. Tissue was collected from 50 patients, and after confirmation of tumor and normal specimens by hematoxylin and eosin (H&E), there were 42 tumor samples and 42 normal adjacent controls.ResultsThere were 42 confirmed carcinoma specimens on H&E, and CRS microscopy identified 37 as carcinoma. Of the 42 normal specimens, CRS microscopy identified 40 as normal. This resulted in a sensitivity of 88.1% and specificity of 95.2% in distinguishing between neoplastic and nonneoplastic images.ConclusionCRS microscopy is a unique label‐free imaging technique that can provide rapid, high‐resolution images and can accurately determine the presence of head and neck carcinoma. This holds potential for implementation into standard practice, allowing frozen margin evaluation even at institutions without a histopathology laboratory.