Bilateral pulmonary embolism without deep venous thrombosis was observed after knee arthroscopy: a case report.

BACKGROUND: Symptomatic pulmonary embolism (PE) after knee arthroscopy is extremely rare. If the embolism is not treated promptly, the patient may die. Bilateral pulmonary embolism with associated pulmonary infarct without concomitant deep vein thrombosis has never been reported following routine knee arthroscopy. CASE PRESENTATION: A 50-year-old female patient with no other risk factors other than hypertension, obesity, varicose veins in the ipsilateral lower extremities and elevated triglyceride (TG) presented to our ward. She had experienced sudden chest tightness, polypnea and fainting after going to the bathroom the morning of the second postoperative day and received emergency medical attention. Colour ultrasonography of the extremities showed no deep vein thrombosis. Lung computed tomography angiography (CTA) showed multiple embolisms scattered in both pulmonary artery branches. Thus, emergency interventional thrombolysis therapy was performed, followed by postoperative symptomatic treatment with drugs with thrombolytic, anticoagulant and protective activities. One week later, lung CTA showed a significant improvement in the PEs compared with those in the previous examination. Since the aetiology of PE and no obvious symptoms were discerned, the patient was discharged. CONCLUSION: Although knee arthroscopy is a minimally invasive and quick procedure, the risk factors for PE in the perioperative period should be considered and fully evaluated to enhance PE detection. Moreover, a timely diagnosis and effective treatment are important measures to prevent and cure PE after knee arthroscopy. Finally, clear guidelines regarding VTE thromboprophylaxis following knee arthroscopy in patients with a low risk of VTE development are needed.

Dexmedetomidine mitigates isoflurane-induced neurodegeneration in fetal rats during the second trimester of pregnancy.

Dexmedetomidine has significant neuroprotective effects. However, whether its protective effects can reduce neurotoxicity caused by isoflurane in fetal brain during the second trimester of pregnancy remains unclear. In this study, timed-pregnancy rats at gestational day 14 spontaneously inhaled 1.5% isoflurane for 4 hours, and were intraperitoneally injected with dexmedetomidine at dosages of 5, 10, 20, and 20 µg/kg 15 minutes before inhalation and after inhalation for 2 hours. Our results demonstrate that 4 hours after inhaling isoflurane, 20 µg/kg dexmedetomidine visibly mitigated isoflurane-induced neuronal apoptosis, reversed downregulation of brain-derived neurotrophic factor expression, and lessened decreased spatial learning and memory ability in adulthood in the fetal rats. Altogether, these findings indicate that dexmedetomidine can reduce neurodegeneration induced by isoflurane in fetal rats during the second trimester of pregnancy. Further, brain-derived neurotrophic factor participates in this process.

Research on a pulmonary nodule segmentation method combining fast self-adaptive FCM and classification.

The key problem of computer-aided diagnosis (CAD) of lung cancer is to segment pathologically changed tissues fast and accurately. As pulmonary nodules are potential manifestation of lung cancer, we propose a fast and self-adaptive pulmonary nodules segmentation method based on a combination of FCM clustering and classification learning. The enhanced spatial function considers contributions to fuzzy membership from both the grayscale similarity between central pixels and single neighboring pixels and the spatial similarity between central pixels and neighborhood and improves effectively the convergence rate and self-adaptivity of the algorithm. Experimental results show that the proposed method can achieve more accurate segmentation of vascular adhesion, pleural adhesion, and ground glass opacity (GGO) pulmonary nodules than other typical algorithms.

Ibalizumab-human CD4 receptor interaction: computational alanine scanning molecular dynamics studies.

Antibody drugs are used in the treatment of many chronic diseases. Recently, however, patients and doctors have encountered problems with drug resistance, and improving the affinity of antibody drugs has therefore become a pressing issue. Ibalizumab is a humanized monoclonal antibody that binds human CD4, the primary receptor for human immunodeficiency virus type 1 (HIV-1). In this study, we sought to identify the key residues of the complementaritydetermining regions (CDRs) of ibalizumab. Virtual alanine mutations (complementarity-determining regions of ibalizumab) were also studied using solvated interaction energies derived from molecular dynamics and the explicit water model. Using 1,000 nanosecond molecular dynamic simulations, we identified six residues: Tyr50 [HCDR2], Tyr53 [HCDR3], Asp58 [HCDR2], Glu95 [HCDR2], and Arg95 [LCDR3]. The Robetta alanine-scanning mutagenesis method and crystallographic information were used to verify our simulations. Our simulated binding affinity of -17.33 kcal/mol is close to the experimentally determined value of -16.48 kcal/mol. Our findings may be useful for protein engineering the structure of the ibalizumab-human CD4 receptor complex. Moreover, the six residues that we identified may play a significant role in the development of bioactive antibody analogues.

Target molecular simulations of RecA family protein filaments.

Modeling of the RadA family mechanism is crucial to understanding the DNA SOS repair process. In a 2007 report, the archaeal RadA proteins function as rotary motors (linker region: I71-K88) such as shown in Figure 1. Molecular simulations approaches help to shed further light onto this phenomenon. We find 11 rotary residues (R72, T75-K81, M84, V86 and K87) and five zero rotary residues (I71, K74, E82, R83 and K88) in the simulations. Inclusion of our simulations may help to understand the RadA family mechanism.

Coarse-grained molecular dynamics simulations of cobra cytotoxin A3 interactions with a lipid bilayer: penetration of loops into membranes.

Cobra cytotoxins, which are small three-looped proteins composed of approximately 60 amino acid residues, primarily act by destroying the bilayer membranes of cells and artificial vesicles. However, the molecular mechanism governing this process is not yet completely understood. We used coarse-grained molecular dynamics (CGMD) simulations to study the mechanism underlying the penetration of cardiotoxin A3 (CTX A3), the major toxic component of Naja atra (Chinese cobra) venom, into a hydrated 1-palmitoyl-2-oleoyl-1-sn-3-phosphatidylcholine (POPC) lipid bilayer. We performed CGMD simulations for three different conformations of the cobra cytotoxin-the tail, lying, and harrow conformations. The results of our simulations indicate that two of these, the tail and lying conformations, did not penetrate the bilayer system. Further, for the harrow conformation, loops 2 and 3 played important roles in penetration of CTX A3 into the bilayer system.

Influence of dentistry students' e-Learning satisfaction: a questionnaire survey.

Dental school graduates operating on patients without having had sufficient practice in school is potentially dangerous to the patients. In order to minimize this danger, it is necessary to establish a virtual learning environment for students. In this study, we incorporated DentSim, a clinical dentistry simulator, into an e-Learning platform. In addition to overcoming the time and space constraints on learning, DentSim can simulate clinical conditions. It also allows students to practice reading case histories and inspecting and diagnosing patients. To construct the research model for this study, we incorporated the four major factors for measuring e-Learner satisfaction-'learner interface', 'learning community', 'content' and 'personalization' with the variable of 'intention to use'. The subjects were 350 dental students studying at the College of Oral Medicine. The structural equation modeling (SEM) results showed that Factors that influenced 'intention to use' include 'learner interface', 'learning community' and 'personalization', and 'intention to use' affect 'e-Learner satisfaction' with the system.

Applying non-synchronized e-learning to the nursing clinical ladder system.

The time and spatial constraints of face-to-face learning often affect nursing staff's inclination to enroll in ladder system training classes. Hence, their competence in clinical care may be unable to meet the requirements of the hospitals they work at. The e-learning mechanism offers a way to overcome such constraints. However, the differences in learners' achievement and satisfaction between traditional face-to-face and non-synchronized e-learning classes in the nursing clinical ladder system have not been thoroughly investigated. In this study, 155 nursing personnel serving at the case hospital, enrolled in N1/N2 ladder courses, were invited to participate as the subjects. The results showed that those who attended face-to-face learning classes reported higher satisfaction but achieved less in class than those in the e-learning class. The factors which influence the subjects' satisfaction with e-learning were investigated and summarized.

Homology modeling, docking, and molecular dynamics reveal HR1039 as a potent inhibitor of 2009 A(H1N1) influenza neuraminidase.

The neuraminidase of the influenza virus is the target of antiviral drugs oseltamivir and zanamivir. Clinical practices have shown that zanamivir and oseltamivir are effective in treating the 2009 A(H1N1) influenza virus. However, drug resistance strains are also emerging. Herein, we report the findings from homology modeling and molecular simulations of 2009 A(H1N1) neuraminidase complexed with zanamivir, oseltamivir, and several herb extracts with potential activities. Our docked oseltamivir and zanamivir results are consistent with previous studies. Based on the same procedure, the docked results of herb extracts HR1039 and HR1040 suggest that they are potential potent inhibitors of neuraminidase. Also, the binding modes of HR1039/HR1040 are different from those of oseltmivir and zanamivir, and may be effective in treating oseltamivir-resistant influenza virus strains.

Potential of mean force of the hepatitis C virus core protein-monoclonal 19D9D6 antibody interaction.

Antigen-antibody interactions are critical for understanding antigen-antibody associations in immunology. To shed further light on this question, we studied a dissociation of the 19D9D6-HCV core protein antibody complex structure. However, forced separations in single molecule experiments are difficult, and therefore molecular simulation techniques were applied in our study. The stretching, that is, the distance between the center of mass of the HCV core protein and the 19D9D6 antibody, has been studied using the potential of mean force calculations based on molecular dynamics and the explicit water model. Our simulations indicate that the 7 residues Gly70, Gly72, Gly134, Gly158, Glu219, Gln221 and Tyr314, the interaction region (antibody), and the 14 interprotein molecular hydrogen bonds might play important roles in the antigen-antibody interaction, and this finding may be useful for protein engineering of this antigen-antibody structure. In addition, the 3 residues Gly134, Gly158 and Tyr314 might be more important in the development of bioactive antibody analogs.

Predictions of binding for dopamine D2 receptor antagonists by the SIE method.

The control of tetralindiol derivative antagonists released through the inhibition of dopamine D2 receptors has been identified as a potential target for the treatment of schizophrenia. We employed molecular dynamics simulation techniques to identify the predicted D2 receptor structure. Homology models of the protein were developed on the basis of crystal structures of four receptor crystals. Compound docking revealed the possible binding mode. In addition, the docking analyses results indicate that five residues (Asp72, Val73, Cys76, Leu183, and Phe187) were responsible for the selectivity of the tetralindiol derivatives. Our molecular dynamics simulations were applied in combination with the solvated interaction energies (SIE) technique to predict the compounds' docking modes in the binding pocket of the D2 receptor. The simulations revealed satisfactory correlations between the calculated and experimental binding affinities of all seven tetralindiol derivative antagonists, as indicated by the obtained R2 value of 0.815.

A molecular dynamics simulation of the human lysozyme - camelid VHH HL6 antibody system.

Amyloid diseases such as Alzheimer's and thrombosis are characterized by an aberrant assembly of specific proteins or protein fragments into fibrils and plaques that are deposited in various tissues and organs. The single-domain fragment of a camelid antibody was reported to be able to combat against wild-type human lysozyme for inhibiting in-vitro aggregations of the amyloidogenic variant (D67H). The present study is aimed at elucidating the unbinding mechanics between the D67H lysozyme and VHH HL6 antibody fragment by using steered molecular dynamics (SMD) simulations on a nanosecond scale with different pulling velocities. The results of the simulation indicated that stretching forces of more than two nano Newton (nN) were required to dissociate the protein-antibody system, and the hydrogen bond dissociation pathways were computed.

Potential of mean force for Syrian hamster prion epitope protein--monoclonal fab 3f4 antibody interaction studies.

Simulating antigen-antibody interactions are crucial for understanding antigen-antibody associations in immunology. To shed further light on this question, we study a dissociation of the Syrian hamster prion epitope protein-fab 3f4 antibody complex structure. The stretching, that is, the distance between the center of mass of the prion epitope protein and the fab 3f4 antibody, has been studied using potential of mean force (PMF) calculations based on molecular dynamics (MD) and the implicit water model. For the complex structure, there are four important intermediates, U-shaped groove on the antibodies, and two inter-protein molecular hydrogen bonds in the stretching process. Use of our simulations may help in understanding the binding mechanics of the complex structure, and thus of significance in the design of antibodies against prion disease.