Biomechanical Comparison of Posterior Fixation Using Spinal Instrumentation and Conventional Posterior Plate Fixation in Unstable Vertical Sacral Fracture

Vertical sacral fracture is one of the most difficult fractures to treat. Posterior fixation using spinal dual rods is a novel method for treating this fracture, but its biomechanical strength has not yet been reported. The aim of this study was to evaluate the biomechanical strength produced by posterior fixation using spinal instrumentation. Sacral fractures were created in eight pelvic bone models and classified into a posterior plate fixation group [P group, n＝4] and a spinal instrumentation group [R group, n＝4]. The biomechanical strength was tested by pushing down on the S1 vertebra from the top. The mean maximum loads were 1,057.4 N and 1,489.4 N in the P and R groups, respectively (p＝0.014). The loads applied to the construct at displacements of 5mm and 7.5mm from the start of the universal testing machine loading were also significantly higher in the R group. The mean stiffness levels in the P and R groups were 88.3N/mm and 119.6N/mm, respectively (p＝0.014). Posterior fixation using spinal instrumentation is biomechanically stronger than conventional posterior plate fixation. This procedure may be the optimal method for treating unstable sacral fracture fixation

Mammalian Lgl Forms a Protein Complex with PAR-6 and aPKC Independently of PAR-3 to Regulate Epithelial Cell Polarity

AbstractBackground: Epithelial cells have apicobasal polarity and an asymmetric junctional complex that provides the bases for development and tissue maintenance. In both vertebrates and invertebrates, the evolutionarily conserved protein complex, PAR-6/aPKC/PAR-3, localizes to the subapical region and plays critical roles in the establishment of a junctional complex and cell polarity. In Drosophila, another set of proteins called tumor suppressors, such as Lgl, which localize separately to the basolateral membrane domain but genetically interact with the subapical proteins, also contribute to the establishment of cell polarity. However, how physically separated proteins interact remains to be clarified.Results: We show that mammalian Lgl competes for PAR-3 in forming an independent complex with PAR-6/aPKC. During cell polarization, mLgl initially colocalizes with PAR-6/aPKC at the cell-cell contact region and is phosphorylated by aPKC, followed by segregation from apical PAR-6/aPKC to the basolateral membrane after cells are polarized. Overexpression studies establish that increased amounts of the mLgl/PAR-6/aPKC complex suppress the formation of epithelial junctions; this contrasts with the previous observation that the complex containing PAR-3 promotes it.Conclusions: These results indicate that PAR-6/aPKC selectively interacts with either mLgl or PAR-3 under the control of aPKC activity to regulate epithelial cell polarity

Deficiency of mDia, an Actin Nucleator, Disrupts Integrity of Neuroepithelium and Causes Periventricular Dysplasia

During development of the central nervous system, the apical-basal polarity of neuroepithelial cells is critical for homeostasis of proliferation and differentiation of neural stem cells. While adherens junctions at the apical surface of neuroepithelial cells are important for maintaining the polarity, the molecular mechanism regulating integrity of these adherens junctions remains largely unknown. Given the importance of actin cytoskeleton in adherens junctions, we have analyzed the role of mDia, an actin nucleator and a Rho effector, in the integrity of the apical adherens junction. Here we show that mDia1 and mDia3 are expressed in the developing brain, and that mDia3 is concentrated in the apical surface of neuroepithelium. Mice deficient in both mDia1 and mDia3 develop periventricular dysplastic mass widespread throughout the developing brain, where neuroepithelial cell polarity is impaired with attenuated apical actin belts and loss of apical adherens junctions. In addition, electron microscopic analysis revealed abnormal shrinkage and apical membrane bulging of neuroepithelial cells in the remaining areas. Furthermore, perturbation of Rho, but not that of ROCK, causes loss of the apical actin belt and adherens junctions similarly to mDia-deficient mice. These results suggest that actin cytoskeleton regulated by Rho-mDia pathway is critical for the integrity of the adherens junctions and the polarity of neuroepithelial cells, and that loss of this signaling induces aberrant, ectopic proliferation and differentiation of neural stem cells

CAUSES OF FUNCTIONAL DECLINE IN ELDERLY HOSPITALIZED PATIENTS RECEIVING EITHER INDIVIDUAL OR EXCLUSIVE REHABILITATION THERAPY: A COHORT STUDY

Background: Recently, exclusive rehabilitation therapy was introduced to prevent functional decline due to hospital-associated deconditioning by managing older inpatients’ activities of daily living in Japan. However, this type of therapy does not provide one-on-one exercises similar to individual rehabilitation therapy. This study aimed to report the present ward conditions and the causes of the functional decline in elderly patients receiving individual or exclusive rehabilitation therapy. Methods: A total of 1,636 inpatients, aged 65 years or older, were included in the study. Barthel Index at admission and discharge was assessed prospectively to analyze functional decline. We further analyzed the causes of functional decline by investigating the inpatient’s medical records. Results: Forty-three inpatients (2.6%) had functional decline during hospitalization. There were no significant differences in age, Barthel Index at the time of admission, and the type of clinical department between inpatients with and without functional decline. The functional decline rate in individual rehabilitation therapy was 8.2%, which was significantly higher compared to exclusive rehabilitation therapy (0.8%). The most common causes of functional decline were a pain, low postoperative physical fitness, malignant neoplasm, and new-onset cerebral stroke. Conclusion: We report the present ward conditions in elderly patients receiving either individual or exclusive rehabilitation therapies. Functional decline was correlated to the inpatients’ disease and conditions. The causes of the functional decline can be classified based on whether rehabilitation was effective or ineffective. If the functional decline was caused by hospital-associated deconditioning, we should address the functional decline by providing appropriate rehabilitation methods

A role for mDia, a Rho-regulated actin nucleator, in tangential migration of interneuron precursors.

神経細胞の配置メカニズムを解明－抑制性神経前駆細胞に特有の移動の機構が明らかに. 京都大学プレスリリース. 2012-1-16.In brain development, distinct types of migration, radial migration and tangential migration, are shown by excitatory and inhibitory neurons, respectively. Whether these two types of migration operate by similar cellular mechanisms remains unclear. We examined neuronal migration in mice deficient in mDia1 (also known as Diap1) and mDia3 (also known as Diap2), which encode the Rho-regulated actin nucleators mammalian diaphanous homolog 1 (mDia1) and mDia3. mDia deficiency impaired tangential migration of cortical and olfactory inhibitory interneurons, whereas radial migration and consequent layer formation of cortical excitatory neurons were unaffected. mDia-deficient neuroblasts exhibited reduced separation of the centrosome from the nucleus and retarded nuclear translocation. Concomitantly, anterograde F-actin movement and F-actin condensation at the rear, which occur during centrosomal and nuclear movement of wild-type cells, respectively, were impaired in mDia-deficient neuroblasts. Blockade of Rho-associated protein kinase (ROCK), which regulates myosin II, also impaired nuclear translocation. These results suggest that Rho signaling via mDia and ROCK critically regulates nuclear translocation through F-actin dynamics in tangential migration, whereas this mechanism is dispensable in radial migration

Quantification system for the viral dynamics of a highly pathogenic simian/human immunodeficiency virus based on an in vitro experiment and a mathematical model

<p>Abstract</p> <p>Background</p> <p>Developing a quantitative understanding of viral kinetics is useful for determining the pathogenesis and transmissibility of the virus, predicting the course of disease, and evaluating the effects of antiviral therapy. The availability of data in clinical, animal, and cell culture studies, however, has been quite limited. Many studies of virus infection kinetics have been based solely on measures of total or infectious virus count. Here, we introduce a new mathematical model which tracks both infectious and total viral load, as well as the fraction of infected and uninfected cells within a cell culture, and apply it to analyze time-course data of an SHIV infection <it>in vitro</it>.</p> <p>Results</p> <p>We infected HSC-F cells with SHIV-KS661 and measured the concentration of Nef<it>-</it>negative (target) and Nef<it>-</it>positive (infected) HSC-F cells, the total viral load, and the infectious viral load daily for nine days. The experiments were repeated at four different MOIs, and the model was fitted to the full dataset simultaneously. Our analysis allowed us to extract an infected cell half-life of 14.1 h, a half-life of SHIV-KS661 infectiousness of 17.9 h, a virus burst size of 22.1 thousand RNA copies or 0.19 TCID₅₀, and a basic reproductive number of 62.8. Furthermore, we calculated that SHIV-KS661 virus-infected cells produce at least 1 infectious virion for every 350 virions produced.</p> <p>Conclusions</p> <p>Our method, combining <it>in vitro </it>experiments and a mathematical model, provides detailed quantitative insights into the kinetics of the SHIV infection which could be used to significantly improve the understanding of SHIV and HIV-1 pathogenesis. The method could also be applied to other viral infections and used to improve the <it>in vitro </it>determination of the effect and efficacy of antiviral compounds.</p

Mitochondrial delivery of mastoparan with transferrin liposomes equipped with a pH-sensitive fusogenic peptide for selective cancer therapy.

Mastoparan (MP), a potent facilitator of mitochondrial permeability transition (PT), could be used as an antitumor agent, if it were encapsulated in a tumor selective delivery system. We recently developed transferrin-modified liposomes (Tf-L) with a pH-sensitive fusogenic peptide (GALA), which delivers an encapsulated fluorescent marker into cytosol efficiently. In this study, we encapsulated MP into Tf-L with GALA for the selective delivery to mitochondria of tumor cells. The MP showed potent PT activity at concentrations above 25 microM in a homogenate of K 562 cells as well as in isolated mitochondria in the presence of phosphate. Tf-L equipped with cholesteryl GALA can release encapsulated sulforhodamine B, while Tf-L failed, as evidenced by confocal laser scanning microscopy. The MP, which was delivered with Tf-L with GALA, released cytochrome c (cyt c) from mitochondria to the cytosol, while free MP released cyt c not only to the cytosol but also extracellulary. These results demonstrate the utility of MP in Tf-L with GALA for cancer therapy

Structure of the rat subcutaneous connective tissue in relation to its sliding mechanism

Mammalian skin can extensively slide over most parts of the body. To study the mechanism of this mobility of the skin, the structure of the subcutaneous connective tissue was examined by light microscopy. The subcutaneous connective tissue was observed to be composed of multiple layers of thin collagen sheets containing elastic fibers. These piled-up collagen sheets were loosely interconnected with each other, while the outer and inner sheets were respectively anchored to the dermis and epimysium by elastic fibers. Collagen fibers in each sheet were variable in diameter and oriented in different directions to form a thin, loose meshwork under conditions without mechanical stretching. When a weak shear force was loaded between the skin and the underlying abdominal muscles, each collagen sheet slid considerably, resulting in a stretching of the elastic fibers which anchor these sheets. When a further shear force was loaded, collagen fibers in each sheet seemed to align in a more parallel manner to the direction of the tension. With the reduction or removal of the force, the arrangement of collagen fibers in each sheet was reversed and the collagen sheets returned to their original shapes and positions, probably with the stabilizing effect of elastic fibers. Blood vessels and nerves in the subcutaneous connective tissue ran in tortuous routes in planes parallel to the unloaded skin, which seemed very adaptable for the movement of collagen sheets. These findings indicate that the subcutaneous connective tissue is extensively mobile due to the presence of multilayered collagen sheets which are maintained by elastic fibers