Cross-validated models of the relationships between neck muscle electromyography and three-dimensional head kinematics during gaze behavior

The object of this study was to model the relationship between neck electromyography (EMG) and three-dimensional (3-D) head kinematics during gaze behavior. In two monkeys, we recorded 3-D gaze, head orientation, and bilateral EMG activity in the sternocleidomastoid, splenius capitis, complexus, biventer cervicis, rectus capitis posterior major, and occipital capitis inferior muscles. Head-unrestrained animals fixated and made gaze saccades between targets within a 60° × 60° grid. We performed a stepwise regression in which polynomial model terms were retained/rejected based on their tendency to increase/decrease a cross-validation-based measure of model generalizability. This revealed several results that could not have been predicted from knowledge of musculoskeletal anatomy. During head holding, EMG activity in most muscles was related to horizontal head orientation, whereas fewer muscles correlated to vertical head orientation and none to small random variations in head torsion. A fourth-order polynomial model, with horizontal head orientation as the only independent variable, generalized nearly as well as higher order models. For head movements, we added time-varying linear and nonlinear perturbations in velocity and acceleration to the previously derived static (head holding) models. The static models still explained most of the EMG variance, but the additional motion terms, which included horizontal, vertical, and torsional contributions, significantly improved the results. Several coordinate systems were used for both static and dynamic analyses, with Fick coordinates showing a marginal (nonsignificant) advantage. Thus, during gaze fixations, recruitment within the neck muscles from which we recorded contributed primarily to position-dependent horizontal orientation terms in our data set, with more complex multidimensional contributions emerging during the head movements that accompany gaze shifts. These are crucial components of the late neuromuscular transformations in a complete model of 3-D head-neck system and should help constrain the study of premotor signals for head control during gaze behaviors.     

Rehabilitation of a large maxillo-facial defect using acrylic resin prosthesis

Large facial defects require definitive surgical reconstruction. However, at times such reconstruction is not possible due to extensive loss of tissues that can not be corrected by surgery alone. In this case, prosthetic restoration of lost facial tissues was carried out. Introduction of newer material which gives life-like appearance to such prosthetic restoration e.g. silicone and poly-ether rubbers, and use of implants to retain these prosthesis have given a new dimension to rehabilitation of such patients. This report presents a case of prosthetic rehabilitation of extensive extra oral defect due to basal cell carcinoma of cheek, using acrylic resin material.     

Genetic analysis of polymerase complex (PA,PB1 and PB2) genes of H9N2 avian influenza viruses from Iran (1999 to 2009)

Objective

To determine the molecular characterization of Polymerase complex (PA, PB1 and PB2) genes of H9N2 avian influenza viruses and the genetic relationship of Iranian H9N2 viruses and other Asian viruses.

Methods

The Polymerase complex (PA, PB1 and PB2) genes from seven isolates of H9N2 viruses isolated from commercial chickens in Iran during 2008-2009 were amplified (by RT-PCR method) and sequenced. Nucleotide sequences (Open Reading Frame: orf) of the PA, PB1 and PB2 genes were used for phylogenetic tree construction.

Results

Most PB2 and PA genes of the H9N2 viruses isolated in 2008-2009 belonged to the unknown avian sublineage which grouped with the 2004 Pakistani H7N3 viruses. The PB1 genes of Iranian viruses indicated greater genetic diversity and shared a high level of similarity to PB1 genes from either H5 or H7 subtypes with compared to established H9N2 Eurasian sublineages.

Conclusions

Our findings demonstrated that the H9N2 viruses in Iran exhibit striking reassortment which has led to the generation of new genotypes.     

The impact of coronary artery endarterectomy on outcomes during coronary artery bypass grafting

Abstract Background: The impact of coronary artery endarterectomy during coronary artery bypass grafting (CABG) has been debated. We examined the early and late outcomes of CABG with endarterectomy (CE) compared to CABG alone. Methods: Patients undergoing isolated CABG operations from 2003 to 2008 were retrospectively reviewed. We identified 99 patients who underwent CE and 3:1 propensity matched them to 297 CABG‐alone patients based upon clinical factors: Society of Thoracic Surgeons (STS) predicted risk of mortality, age, gender, year of surgery, and ejection fraction. Patient risk factors as well as short‐ and long‐term outcomes were compared by univariate and Kaplan‐Meier analysis. Results: Preoperative risk factors were similar between patients undergoing CE or CABG alone. Cross‐clamp times (95.6 vs. 71.8 minutes, p = 0.0001) and perfusion times (121.8 vs. 92.7 minutes, p = 0.0001) were longer in patients undergoing CE. Operative mortality (4.0% vs. 1.3%, p = 0.112) and postoperative complications were not significantly different between groups. Patients undergoing coronary endarterectomy incurred longer ICU (75.06 vs. 48.64 hours, p = 0.001) and hospital stays (9.01 vs. 7.7 days, p = 0.034). Long‐term mortality (mean follow‐up = 27.7 ± 17.7 months) was equivalent despite revascularization technique (p = 0.13); however, patients undergoing CE encountered worse overall freedom from myocardial infarction (MI) (p = 0.03). Conclusion: Patients undergoing CABG with coronary CE required longer ventilatory support and ICU stay yet have comparable operative mortality, major complication rates, and long‐term survival to isolated CABG. Coronary endarterectomy should be considered an acceptable adjunct to CABG for patients with extensive coronary artery disease to achieve complete revascularization. (J Card Surg 2011;26:247‐253)     

Modeling cytoplasmic release of encapsulated oligonucleotides from cationic liposomes

Transfection activity of antisense oligodeoxynucleotides (ODN)-loaded cationic liposomes is mainly restricted by uptake and ODN release into cytoplasm, which is difficult to evaluate in cell culture studies. Well-designed models of cellular membranes, aim of the present study, might facilitate investigation of such processes. In this investigation, a phosphorothioate ODN was actively encapsulated in a DODAP-containing cationic liposome by ethanol injection with 73% efficiency. ODN release was determined by fluorescence dequenching of FITC-ODN upon incubation of liposomes with early endosomal (EE), late endosomal (LE) and plasma membranes (PM) models. LE provided the highest release (up to 76%) in a temperature-dependent manner. Release by EE (<16%), total PM (<11%) and PM external layer ( approximately 0) were not temperature sensitive. These differences are attributed to lipid charge, chain mobility, critical packing parameter and cholesterol content of the models. Intracellular distribution of FITC-ODN, determined by fluorescence microscopy and flowcytometry in the presence and absence of sodium azide, confirmed that liposomes were internalized mainly via endocytosis; hence inability of our PL models to simulate such active processes. Instead, release of ODN from endosomes into cytoplasm was pH-sensitive and in good agreement with model membrane studies in terms of amount and mechanism.     

Growth characteristics of ChimeriVax-Den vaccine viruses in Aedes aegypti and Aedes albopictus from Thailand

Four chimeric yellow fever (YF) 17D-dengue (DEN) candidate vaccine viruses (ChimeriVax-DEN; Acambis, Cambridge, MA) were characterized in Aedes aegypti and Ae. albopictus mosquitoes collected from Thailand. The four vaccine viruses contained the relevant prM and E genes of wild-type dengue viruses (DENV; serotypes 1-4) substituted for the equivalent genes in the YF vaccine virus (17D) backbone. Each chimera conferred protection against the homologous DENV serotype; a tetravalent mix of all four chimeras stimulates an immune response against all serotypes. Field-collected mosquitoes from Thailand were fed on blood containing each of the viruses under study and held 21 days after infection. Infection and dissemination rates were based on antigen detection in the body or head tissues, respectively. All four wild-type DENV serotypes infected and disseminated, but the candidate vaccine viruses were highly attenuated in mosquitoes with respect to infection and especially with respect to dissemination. Considering the low level viremias anticipated in humans vaccinated with these viruses, it is predicted that the risks of infection and transmission by mosquitoes in nature is minimal.     

Worldwide risk factors for heart failure: A systematic review and pooled analysis

Background

Heart failure risk factors are diverse and likely to vary among world regions. Systematic review and pooled analysis were used to describe contributions of major underlying risk factors for heart failure in six world regions.

Methods

Electronic databases were systematically searched, and 37 clinic-based studies representing 40 countries published in 1980–2008 and reporting underlying risk factors for heart failure were included. Risk factors were classified as ischemic heart disease (IHD), hypertension, rheumatic/other valvular heart disease, cardiopulmonary disease, cardiomyopathy, and “other”. Crude and age- and sex-adjusted risk factor prevalences were estimated for each region using a regression analysis, under specifications of overlapping as well as additive contributions.

Results

Many heart failure cases were assigned multiple underlying risk factors, leading to a considerable overlap. Crude IHD prevalence among heart failure patients was > 50% in Europe and North America, approximately 30–40% in East Asia and Latin America and the Caribbean, and < 10% in Sub-Saharan Africa. Age and sex adjustment attenuated regional differences in IHD-as-risk factor but IHD remained rare in Sub-Saharan Africa. Hypertension prevalence was high in heart failure patients of all regions but the highest in Eastern and Central Europe and Sub-Saharan Africa (age- and sex-adjusted, 35.0% and 32.6%, respectively). Cardiomyopathy was most common in Latin America, the Caribbean and Sub-Saharan Africa (age- and sex-adjusted, 19.8% and 25.7%).

Conclusions

Heart failure risk factors vary substantially among world regions. More detailed regional heart failure epidemiology studies are needed in order to quantify the global burden of heart failure and identify regional prevention and treatment strategies.