The flying buttress construct for posterior spinopelvic fixation: a technical note

<p>Abstract</p> <p>Background</p> <p>Posterior fusion of the spine to the pelvis in paediatric and adult spinal deformity is still challenging. Especially assembling of the posterior rod construct to the iliac screw is considered technically difficult. A variety of spinopelvic fixation techniques have been developed. However, extreme bending of the longitudinal rods or the use of 90-degree lateral offset connectors proved to be difficult, because the angle between the rod and the iliac screw varies from patient to patient.</p> <p>Methods</p> <p>We adopted a new spinopelvic fixation system, in which iliac screws are side-to-side connected to the posterior thoracolumbar rod construct, independent of the angle between the rod and the iliac screw. Open angled parallel connectors are used to connect short iliac rods from the posterior rod construct to the iliac screws at both sides. The construct resembles in form and function an architectural Flying Buttress, or lateral support arches, used in Gothic cathedrals.</p> <p>Results and discussion</p> <p>Three different cases that illustrate the Flying Buttress construct for spinopelvic fixation are reported here with the clinical details, radiographic findings and surgical technique used.</p> <p>Conclusion</p> <p>The Flying Buttress construct may offer an alternative surgical option for spinopelvic fixation in circumstances wherein coronal or sagittal balance cannot be achieved, for example in cases with significant residual pelvic obliquity, or in revision spinal surgery for failed lumbosacral fusion.</p

Factors affecting medical students in formulating their specialty preferences in Jordan

<p>Abstract</p> <p>Background</p> <p>In recent years there has been a growing appreciation of the issues of career preference in medicine as it may affect student learning and academic performance. However, no such studies have been undertaken in medical schools in Jordan. Therefore, we carried out this study to investigate the career preferences of medical students at Jordan University of Science and Technology and determine factors that might influence their career decisions.</p> <p>Methods</p> <p>A cross-sectional questionnaire-based survey was carried out among second, fourth and sixth year medical students at the Jordan University of Science and Technology, Irbid, Jordan during the academic year 2006/2007. A total of 440 students answered the questionnaire which covered demographic characteristics, specialty preferences, and the factors that influenced these career preferences. Possible influences were selected on the basis of a literature review and discussions with groups of medical students and physicians. Students were asked to consider 14 specialty options and select the most preferred career preference.</p> <p>Results</p> <p>The most preferred specialty expressed by male students was surgery, followed by internal medicine and orthopaedics, while the specialty most preferred by female students was obstetrics and gynaecology, followed by pediatrics and surgery. Students showed little interest in orthopedics, ophthalmology, and dermatology. While 3.1% of females expressed interest in anesthesiology, no male students did. Other specialties were less attractive to most students.</p> <p>Intellectual content of the specialty and the individual's competencies were the most influential on their preference of specialty. Other influential factors were the "reputation of the specialty", "anticipated income", and "focus on urgent care".</p> <p>Conclusion</p> <p>Surgery, internal medicine, pediatrics, and obstetrics and gynaecology were the most preferred specialty preferences of medical students at Jordan University of Science and Technology.</p

Zinc uptake promotes myoblast differentiation via Zip7 transporter and activation of Akt signalling transduction pathway

[EN] Myogenic regeneration occurs through a chain of events beginning with the output of satellite cells from quiescent state, formation of competent myoblasts and later fusion and differentiation into myofibres. Traditionally, growth factors are used to stimulate muscle regeneration but this involves serious off-target effects, including alterations in cell homeostasis and cancer. In this work, we have studied the use of zinc to trigger myogenic differentiation. We show that zinc promotes myoblast proliferation, differentiation and maturation of myofibres. We demonstrate that this process occurs through the PI3K/Akt pathway, via zinc stimulation of transporter Zip7. Depletion of zinc transporter Zip7 by RNA interference shows reduction of both PI3K/Akt signalling and a significant reduction of multinucleated myofibres and myotubes development. Moreover, we show that mature myofibres, obtained through stimulation with high concentrations of zinc, accumulate zinc and so we hypothesise their function as zinc reservoirs into the cell.P.R. and R.S. acknowledges support from the Spanish Ministry of Economy and Competitiveness (MINECO) (MAT2015-69315-C3-1-R). P.R. acknowledges the Fondo Europeo de Desarrollo Regional (FEDER). CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. R.S. acknowledges the support from the Spanish MECD through the PRX16/00208 grant. MSS acknowledges support from the European Research Council (ERC - HealInSynergy 306990) and the UK Engineering and Physical Sciences Research Council (EPSRC - EP/P001114/1)Mnatsakanyan, H.; Sabater I Serra, R.; Rico Tortosa, PM.; Salmerón Sánchez, M. (2018). Zinc uptake promotes myoblast differentiation via Zip7 transporter and activation of Akt signalling transduction pathway. Scientific Reports. 8:1-14. https://doi.org/10.1038/s41598-018-32067-0S1148Frontera, W. R. & Ochala, J. Skeletal muscle: a brief review of structure and function. Calcif. Tissue Int. 96, 183–195 (2015).Wolfe, R. R., Frontera, W. R. & Ochala, J. The underappreciated role of muscle in health and disease. Am. J. Clin. Nutr. 84, 475–82 (2006).Sciorati, C., Rigamonti, E., Manfredi, A. A. & Rovere-Querini, P. Cell death, clearance and immunity in the skeletal muscle. Cell Death Differ. 23, 927–937 (2016).Wang, Y. X. & Rudnicki, M. A. Satellite cells, the engines of muscle repair. Nat. Rev. Mol. Cell Biol. 13, 127–133 (2011).Yin, H., Price, F. & Rudnicki, M. A. Satellite cells and the muscle stem cell niche. Physiol. Rev. 93, 23–67 (2013).Dhawan, J. & Rando, T. A. Stem cells in postnatal myogenesis: Molecular mechanisms of satellite cell quiescence, activation and replenishment. Trends Cell Biol. 15, 666–673 (2005).Yun, K. & Wold, B. Skeletal muscle determination and differentiation: Story of a core regulatory network and its context. Curr. Opin. Cell Biol. 8, 877–889 (1996).Gharaibeh, B. et al. Biological approaches to improve skeletal muscle healing after injury and disease. Birth Defects Res. Part C Embryo Today Rev. 96, 82–94 (2012).Schiaffino, S. & Mammucari, C. Regulation of skeletal muscle growth by the IGF1-Akt/PKB pathway: insights from genetic models. Skelet. Muscle 1, 4 (2011).Sandri, M. Signaling in muscle atrophy and hypertrophy. Physiology (Bethesda). 23, 160–70 (2008).Karalaki, M., Fili, S., Philippou, A. & Koutsilieris, M. Muscle regeneration: cellular and molecular events. In Vivo 23, 779–96 (2009).Fujio, Y. et al. Cell cycle withdrawal promotes myogenic induction of Akt, a positive modulator of myocyte survival. Mol. Cell. Biol. 19, 5073–82 (1999).Wilson, E. M. & Rotwein, P. Control of MyoD function during initiation of muscle differentiation by an autocrine signaling pathway activated by insulin-like growth factor-II. J. Biol. Chem. 281, 29962–29971 (2006).Sun, L., Liu, L., Yang, X. & Wu, Z. Akt binds prohibitin 2 and relieves its repression of MyoD and muscle differentiation. J. Cell Sci. 117, 3021–3029 (2004).Milner, D. & Cameron, J. Muscle repair and regeneration: stem cells, scaffolds, and the contributions of skeletal muscle to amphibian limb regeneration. Curr. Top. Microbiol. Immunol. 367, 133–159 (2013).Liu, C. et al. PI3K/Akt signaling transduction pathway is involved in rat vascular smooth muscle cell proliferation induced by apelin-13. Acta Biochim Biophys Sin 42, 396–402 (2010).Eriksson, M., Taskinen, M. & Leppä, S. Mitogen Activated Protein Kinase-Dependent Activation of c-Jun and c-Fos is required for Neuronal differentiation but not for Growth and Stress Reposne in PC12 cells. J. Cell. Physiol. 207, 12–22 (2006).Arsic, N. et al. Vascular endothelial growth factor stimulates skeletal muscle regeneration in Vivo. Mol. Ther. 10, 844–854 (2004).Borselli, C. et al. Functional muscle regeneration with combined delivery of angiogenesis and myogenesis factors. Proc. Natl. Acad. Sci. USA 107, 3287–3292 (2010).Hanft, J. R. et al. Phase I trial on the safety of topical rhVEGF on chronic neuropathic diabetic foot ulcers. J. Wound Care 17(30–2), 34–7 (2008).Simón-Yarza, T. et al. Vascular endothelial growth factor-delivery systems for cardiac repair: An overview. Theranostics 2, 541–552 (2012).Briquez, P. S., Hubbell, J. A. & Martino, M. M. Extracellular Matrix-Inspired Growth Factor Delivery Systems for Skin Wound Healing. Adv. Wound Care 4, 479–489 (2015).Barthel, A., Ostrakhovitch, E. A., Walter, P. L., Kampkötter, A. & Klotz, L. O. Stimulation of phosphoinositide 3-kinase/Akt signaling by copper and zinc ions: Mechanisms and consequences. Arch. Biochem. Biophys. 463, 175–182 (2007).Ostrakhovitch, E. A., Lordnejad, M. R., Schliess, F., Sies, H. & Klotz, L.-O. Copper ions strongly activate the phosphoinositide-3-kinase/Akt pathway independent of the generation of reactive oxygen species. Arch. Biochem. Biophys. 397, 232–239 (2002).Kaur, K., Gupta, R., Saraf, S. A. & Saraf, S. K. Zinc: The metal of life. Compr. Rev. Food Sci. Food Saf. 13, 358–376 (2014).Coleman, J. E. Zinc proteins: enzymes, storage proteins, transcription factors, and replication proteins. Annu. Rev. Biochem. 61, 897–946 (1992).Fukada, T. & Kambe, T. Molecular and genetic features of zinc transporters in physiology and pathogenesis. Metallomics 3, 662–674 (2011).Murakami, M. & Hirano, T. Intracellular zinc homeostasis and zinc signaling. Cancer Sci. 99, 1515–1522 (2008).Hogstrand, C., Kille, P., Nicholson, R. I. & Taylor, K. M. Zinc transporters and cancer: a potential role for ZIP7 as a hub for tyrosine kinase activation. Trends Mol. Med. 15, 101–111 (2009).Kolenko, V., Teper, E., Kutikov, A. & Uzzo, R. Zinc and zinc transporters in prostate carcinogenesis. Nat. Rev. Urol. 10, 219–26 (2013).Myers, S. A., Nield, A., Chew, G. S. & Myers, M. A. The zinc transporter, Slc39a7 (Zip7) is implicated in glycaemic control in skeletal muscle cells. Plos One 8 (2013).Kambe, T., Tsuji, T., Hashimoto, A. & Itsumura, N. The Physiological, Biochemical, and Molecular Roles of Zinc Transporters in Zinc Homeostasis and Metabolism. Physiol. Rev. 95, 749–784 (2015).Jinno, N., Nagata, M. & Takahashi, T. Marginal zinc deficiency negatively affects recovery from muscle injury in mice. Biol. Trace Elem. Res. 158, 65–72 (2014).Taylor, K. M., Hiscox, S., Nicholson, R. I., Hogstrand, C. & Kille, P. Protein Kinase CK2 Triggers Cytosolic Zinc Signaling Pathways by Phosphorylation of Zinc Channel ZIP7. Sci. Signal. 5, ra11–ra11 (2012).Yamasaki, S. et al. Zinc is a novel intracellular second messenger. J. Cell Biol. 177, 637–45 (2007).Sumitani, S., Goya, K., Testa, J. R., Kouhara, H. & Kasayama, S. Akt1 and Akt2 differently regulate muscle creatine kinase and myogenin gene transcription in insulin-induced differentiation of C2C12 myoblasts. Endocrinology 143, 820–828 (2002).Ohashi, K. et al. Zinc promotes proliferation and activation of myogenic cells via the PI3K/Akt and ERK signaling cascade. Exp. Cell Res. 333, 228–237 (2015).Chesters, J. K. In Zinc in human biology 53, 109–118 (1989).Burattini, S. et al. C2C12 murine myoblasts as a model of skeletal muscle development: Morpho-functional characterization. Eur. J. Histochem. 48, 223–233 (2004).Mnatsakanyan, H. et al. Controlled Assembly of Fibronectin Nanofibrils Triggered by Random Copolymer Chemistry. ACS Appl. Mater. Interfaces 7, 18125–18135 (2015).Jeong, J. & Eide, D. J. The SLC39 family of zinc transporters. Molecular Aspects of Medicine 34, 612–619 (2013).Huang, L., Kirschke, C. P., Zhang, Y. & Yan, Y. Y. The ZIP7 gene (Slc39a7) encodes a zinc transporter involved in zinc homeostasis of the Golgi apparatus. J. Biol. Chem. 280, 15456–15463 (2005).Vallee, B. L. & Falchuk, K. H. The biochemical basis of zinc physiology. Physiological reviews 73 (1993).Ganju, N. & Eastman, A. Zinc inhibits Bax and Bak activation and cytochrome c release induced by chemical inducers of apoptosis but not by death-receptor-initiated pathways. Cell Death Differ. 10, 652–61 (2003).Chai, F., Truong-Tran, A. Q., Ho, L. H. & Zalewski, P. D. Regulation of caspase activation and apoptosis by cellular zinc fluxes and zinc deprivation: A review. Immunol. Cell Biol. 77, 272–278 (1999).Smith, P. J., Wiltshire, M., Furon, E., Beattie, J. H. & Errington, R. J. Impact of overexpression of metallothionein-1 on cell cycle progression and zinc toxicity. Am. J. Physiol. Cell Physiol. 295, C1399–C1408 (2008).Bozym, R. A. et al. Free zinc ions outside a narrow concentration range are toxic to a variety of cells in vitro. Exp. Biol. Med. (Maywood). 235, 741–50 (2010).Plum, L. M., Rink, L. & Hajo, H. The essential toxin: Impact of zinc on human health. Int. J. Environ. Res. Public Health 7, 1342–1365 (2010).Chen, C.-J. & Liao, S.-L. Zinc toxicity on neonatal cortical neurons: involvement of glutathione chelation. J. Neurochem. 85, 443–453 (2003).Chassot, A. A. et al. Confluence-induced cell cycle exit involves pre-mitotic CDK inhibition by p27Kip1 and cyclin D1 downregulation. Cell Cycle 7, 2038–2046 (2008).Spencer, S. L. et al. XThe proliferation-quiescence decision is controlled by a bifurcation in CDK2 activity at mitotic exit. Cell 155, 369–383 (2013).Walsh, K. & Perlman, H. Cell cycle exit upon myogenic differentiation. Curr. Opin. Genet. Dev. 7, 597–602 (1997).Puri, P. L. & Sartorelli, V. Regulation of muscle regulatory factors by DNA-binding, interacting proteins, and post-transcriptional modifications. Journal of Cellular Physiology 185, 155–173 (2000).Zammit, P. S., Partridge, T. A. & Yablonka-Reuveni, Z. The skeletal muscle satellite cell: the stem cell that came in from the cold. J Histochem Cytochem 54, 1177–1191 (2006).McCord, M. C. & Aizenman, E. The role of intracellular zinc release in aging, oxidative stress, and Alzheimer’s disease. Front. Aging Neurosci. 6, 1–16 (2014).Dirksen, R. T. Sarcoplasmic reticulum–mitochondrial through-space coupling in skeletal muscle. This paper is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic. Appl. Physiol. Nutr. Metab. 34, 389–395 (2009).Groth, C., Sasamura, T., Khanna, M. R., Whitley, M. & Fortini, M. E. Protein trafficking abnormalities in Drosophila tissues with impaired activity of the ZIP7 zinc transporter Catsup. Development 140, 3018–3027 (2013).Ellis, C. D. et al. Zinc and the Msc2 zinc transporter protein are required for endoplasmic reticulum function. J. Cell Biol. 166, 325–335 (2004).Koch, U., Lehal, R. & Radtke, F. Stem cells living with a Notch. Development 140, 689–704 (2013).Gardner, S., Anguiano, M. & Rotwein, P. Defining Akt actions in muscle differentiation. Am. J. Physiol. Physiol. 303, C1292–C1300 (2012).Knight, J. D. & Kothary, R. The myogenic kinome: protein kinases critical to mammalian skeletal myogenesis. Skelet. Muscle 1, 29 (2011).Roth, S. M. Genetic aspects of skeletal muscle strength and mass with relevance to sarcopenia. Bonekey Rep. 1, 1–7 (2012).Mebratu, Y. & Tesfaigzi, Y. How ERK1/2 Activation Controls Cell Proliferation and Cell Death Is Subcellular Localization the Answer? Cell Cycle 8, 1168–1175 (2009)

Differential Susceptibility of Interneurons Expressing Neuropeptide Y or Parvalbumin in the Aged Hippocampus to Acute Seizure Activity

Acute seizure (AS) activity in old age has an increased predisposition for evolving into temporal lobe epilepsy (TLE). Furthermore, spontaneous seizures and cognitive dysfunction after AS activity are often intense in the aged population than in young adults. This could be due to an increased vulnerability of inhibitory interneurons in the aged hippocampus to AS activity. We investigated this issue by comparing the survival of hippocampal GABA-ergic interneurons that contain the neuropeptide Y (NPY) or the calcium binding protein parvalbumin (PV) between young adult (5-months old) and aged (22-months old) F344 rats at 12 days after three-hours of AS activity. Graded intraperitoneal injections of the kainic acid (KA) induced AS activity and a diazepam injection at 3 hours after the onset terminated AS-activity. Measurement of interneuron numbers in different hippocampal subfields revealed that NPY+ interneurons were relatively resistant to AS activity in the aged hippocampus in comparison to the young adult hippocampus. Whereas, PV+ interneurons were highly susceptible to AS activity in both age groups. However, as aging alone substantially depleted these populations, the aged hippocampus after three-hours of AS activity exhibited 48% reductions in NPY+ interneurons and 70% reductions in PV+ interneurons, in comparison to the young hippocampus after similar AS activity. Thus, AS activity-induced TLE in old age is associated with far fewer hippocampal NPY+ and PV+ interneuron numbers than AS-induced TLE in the young adult age. This discrepancy likely underlies the severe spontaneous seizures and cognitive dysfunction observed in the aged people after AS activity

Preconditioning with Physiological Levels of Ethanol Protect Kidney against Ischemia/Reperfusion Injury by Modulating Oxidative Stress

Oxidative stress due to excessive production of reactive oxygen species (ROS) and subsequent lipid peroxidation plays a critical role in renal ischemia/reperfusion (IR) injury. The purpose of current study is to demonstrate the effect of antecedent ethanol exposure on IR-induced renal injury by modulation of oxidative stress.Bilateral renal warm IR was induced in male C57BL/6 mice after ethanol or saline administration. Blood ethanol concentration, kidney function, histological damage, inflammatory infiltration, cytokine production, oxidative stress, antioxidant capacity and Aldehyde dehydrogenase (ALDH) enzymatic activity were assessed to evaluate the impact of antecedent ethanol exposure on IR-induced renal injury.After bilateral kidney ischemia, mice preconditioned with physiological levels of ethanol displayed significantly preserved renal function along with less histological tubular damage as manifested by the reduced inflammatory infiltration and cytokine production. Mechanistic studies revealed that precondition of mice with physiological levels of ethanol 3 h before IR induction enhanced antioxidant capacity characterized by significantly higher superoxidase dismutase (SOD) activities. Our studies further demonstrated that ethanol pretreatment specifically increased ALDH2 activity, which then suppressed lipid peroxidation by promoting the detoxification of Malondialdehyde (MDA) and 4-hydroxynonenal (HNE).Our results provide first line of evidence indicating that antecedent ethanol exposure can provide protection for kidneys against IR-induced injury by enhancing antioxidant capacity and preventing lipid peroxidation. Therefore, ethanol precondition and ectopic ALDH2 activation could be potential therapeutic approaches to prevent renal IR injury relevant to various clinical conditions

SIRT1 Undergoes Alternative Splicing in a Novel Auto-Regulatory Loop with p53

Background: The NAD-dependent deacetylase SIRT1 is a nutrient-sensitive coordinator of stress-tolerance, multiple homeostatic processes and healthspan, while p53 is a stress-responsive transcription factor and our paramount tumour suppressor. Thus, SIRT1-mediated inhibition of p53 has been identified as a key node in the common biology of cancer, metabolism, development and ageing. However, precisely how SIRT1 integrates such diverse processes remains to be elucidated. Methodology/Principal Findings: Here we report that SIRT1 is alternatively spliced in mammals, generating a novel SIRT1 isoform: SIRT1-DExon8. We show that SIRT1-DExon8 is expressed widely throughout normal human and mouse tissues, suggesting evolutionary conservation and critical function. Further studies demonstrate that the SIRT1-DExon8 isoform retains minimal deacetylase activity and exhibits distinct stress sensitivity, RNA/protein stability, and protein-protein interactions compared to classical SIRT1-Full-Length (SIRT1-FL). We also identify an auto-regulatory loop whereby SIRT1-DExon8 can regulate p53, while in reciprocal p53 can influence SIRT1 splice variation. Conclusions/Significance: We characterize the first alternative isoform of SIRT1 and demonstrate its evolutionary conservation in mammalian tissues. The results also reveal a new level of inter-dependency between p53 and SIRT1, two master regulators of multiple phenomena. Thus, previously-attributed SIRT1 functions may in fact be distributed betwee

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

Describing knowledge encounters in healthcare: a mixed studies systematic review and development of a classification

This review was self-funded