Search

Introduction and Aim: Surgical navigation has evolved as a vital tool in maxillofacial surgery, offering precise and patient-specific data. This study explores the clinical applications and accuracy of intraoperative tool tracking in maxillofacial surgery. (2) Materials and Methods: The research includes 42 patients with various pathologies who underwent surgeries assisted by a surgical navigation system using tracked instruments. Four representative cases are exhibited in the study: the first case involving coronoid hyperplasia with mouth opening deficit, the second case addressing naso-orbital-ethmoidal-frontal ossifying fibroma resection, the third case showcasing a subapical osteotomy (Köle) for a class III dentoskeletal malocclusion, and the fourth one exposing the treatment of a recurrent ameloblastoma. (3) Results: The results indicate that surgical navigation with tracked instruments provides high precision (<1.5 mm error), reduced surgical time, and a less invasive approach. (4) Conclusions: This study highlights the potential for reproducible outcomes and increased safety, especially in complex cases. Despite some limitations, the synergy between surgical navigation and tracked instruments offers a promising approach in maxillofacial surgery, expanding its applications beyond current practices.

Storytelling is a particular kind of action because it is made up of words. So it seems to bring together the different principles of doing and knowing. I try to approach storytelling to other performing arts, in particular theater, because I think it is a peculiarity of performing arts to hold together mind and body, praxis and theories, and to overcome old categories and fictional opposition between them. Theater is a meeting between actor and spectator with a language made up of signs and symbols, performed by a body-mind. In this sense performing arts are sweeping and advanced fields in which theoretical and philosophical theories can become wider. The roots of theater are the same as those of religion and rituals. Theater was born as a way to represent the conflict between opposite forces and opposite gods, Apollo and Dionysus, as Nietzsche taught. The birth of theater was involved in the relationship between good and evil, as a way to understand and represent them, in order to tell and to act, this kind of cosmic conflict with performances. In this sense I think theater could preserve an ancient, but still actual, way of social innovation. Theater and its forms, tragedy and comedy, and its deep research in active culture, could help storytellers to deeply penetrate the negative aspects of a social concern, in order to represent it, act it and lay the foundation to draw forth the best part of it.

Contains fulltext : 153406.pdf (publisher's version ) (Closed access), Dysfunction of complex I (CI) of the mitochondrial electron transport chain (ETC) features prominently in human pathology. Cell models of ETC dysfunction display adaptive survival responses that still are poorly understood but of relevance for therapy development. Here we comprehensively examined how primary human skin fibroblasts adapt to chronic CI inhibition. CI inhibition triggered transient and sustained changes in metabolism, redox homeostasis and mitochondrial (ultra)structure but no cell senescence/death. CI-inhibited cells consumed no oxygen and displayed minor mitochondrial depolarization, reverse-mode action of complex V, a slower proliferation rate and futile mitochondrial biogenesis. Adaptation was neither prevented by antioxidants nor associated with increased PGC1-alpha/SIRT1/mTOR levels. Survival of CI-inhibited cells was strictly glucose-dependent and accompanied by increased AMPK-alpha phosphorylation, which occurred without changes in ATP or cytosolic calcium levels. Conversely, cells devoid of AMPK-alpha died upon CI inhibition. Chronic CI inhibition did not increase mitochondrial superoxide levels or cellular lipid peroxidation and was paralleled by a specific increase in SOD2/GR, whereas SOD1/CAT/Gpx1/Gpx2/Gpx5 levels remained unchanged. Upon hormone stimulation, fully adapted cells displayed aberrant cytosolic and ER calcium handling due to hampered ATP fueling of ER calcium pumps. It is concluded that CI dysfunction triggers an adaptive program that depends on extracellular glucose and AMPK-alpha. This response avoids cell death by suppressing energy crisis, oxidative stress induction and substantial mitochondrial depolarization.

Contains fulltext : 130251.pdf (preprint version ) (Open Access)

Item does not contain fulltext, The human NDUFS4 gene encodes an accessory subunit of the first mitochondrial oxidative phosphorylation complex (CI) and, when mutated, is associated with progressive neurological disorders. Here we analyzed primary muscle and skin fibroblasts from NDUFS4(-/-) mice with respect to reactive oxygen species (ROS) levels and mitochondrial morphology. NDUFS4(-/-) fibroblasts displayed an inactive CI subcomplex on native gels but proliferated normally and showed no obvious signs of apoptosis. Oxidation of the ROS sensor hydroethidium was increased and mitochondria were less branched and/or shorter in NDUFS4(-/-) fibroblasts. We discuss the relevance of these findings with respect to previous results and therapy development.

1 januari 2012, Item does not contain fulltext, Complex I (CI) represents a major entry point of electrons in the mitochondrial electron transport chain (ETC). It consists of 45 different subunits, encoded by the mitochondrial (mtDNA) and nuclear DNA (nDNA). In humans, mutations in nDNA-encoded subunits cause severe neurodegenerative disorders like Leigh Syndrome with onset in early childhood. The pathophysiological mechanism of these disorders is still poorly understood. Here we summarize the current knowledge concerning the consequences of nDNA-encoded CI mutations in patient-derived cells, present mouse models for human CI deficiency, and discuss potential treatment strategies for CI deficiency.

Contains fulltext : 110064.pdf (publisher's version ) (Closed access), AIMS: Cell regulation by signaling reactive oxygen species (sROS) is often incorrectly studied through extracellular oxidant addition. Here, we used the membrane-permeable antioxidant Trolox to examine the role of sROS in mitochondrial morphology, oxidative phosphorylation (OXPHOS), and cytosolic calcium (Ca(2+)) handling in healthy human skin fibroblasts. RESULTS AND INNOVATION: Trolox treatment reduced the levels of 5-(and-6)-chloromethyl-2',7'-dichlorodihydro-fluorescein (CM-H(2)DCF) oxidizing ROS, lowered cellular lipid peroxidation, and induced a less oxidized mitochondrial thiol redox state. This was paralleled by increased glutathione- and mitofusin-dependent mitochondrial filamentation, increased expression of fully assembled mitochondrial complex I, elevated activity of citrate synthase and OXPHOS enzymes, and a higher cellular O(2) consumption. In contrast, Trolox did not alter hydroethidium oxidation, cytosolic thiol redox state, mitochondrial NAD(P)H levels, or mitochondrial membrane potential. Whole genome expression profiling revealed that Trolox did not trigger significant changes in gene expression, suggesting that Trolox acts downstream of this process. Cytosolic Ca(2+) transients, induced by the hormone bradykinin, were of a higher amplitude and decayed faster in Trolox-treated cells. These effects were dose-dependently antagonized by hydrogen peroxide. CONCLUSIONS: Our findings suggest that Trolox-sensitive sROS are upstream regulators of mitochondrial mitofusin levels, morphology, and function in healthy human skin fibroblasts. This information not only facilitates the interpretation of antioxidant effects in cell models (of oxidative-stress), but also contributes to a better understanding of ROS-related human pathologies, including mitochondrial disorders.

1 oktober 2012, Item does not contain fulltext, Human mitochondrial complex I (CI) deficiency is associated with progressive neurological disorders. To better understand the CI pathomechanism, we here studied how deletion of the CI gene NDUFS4 affects cell metabolism. To this end we compared immortalized mouse embryonic fibroblasts (MEFs) derived from wildtype (wt) and whole-body NDUFS4 knockout (KO) mice. Mitochondria from KO cells lacked the NDUFS4 protein and mitoplasts displayed virtually no CI activity, moderately reduced CII, CIII and CIV activities and normal citrate synthase and CV (F(o)F(1)-ATPase) activity. Native electrophoresis of KO cell mitochondrial fractions revealed two distinct CI subcomplexes of ~830kDa (enzymatically inactive) and ~200kDa (active). The level of fully-assembled CII-CV was not affected by NDUFS4 gene deletion. KO cells exhibited a moderately reduced maximal and routine O(2) consumption, which was fully inhibited by acute application of the CI inhibitor rotenone. The aberrant CI assembly and reduced O(2) consumption in KO cells were fully normalized by NDUFS4 gene complementation. Cellular [NAD(+)]/[NADH] ratio, lactate production and mitochondrial tetramethyl rhodamine methyl ester (TMRM) accumulation were slightly increased in KO cells. In contrast, NDUFS4 gene deletion did not detectably alter [NADP(+)]/[NADPH] ratio, cellular glucose consumption, the protein levels of hexokinases (I and II) and phosphorylated pyruvate dehydrogenase (P-PDH), total cellular adenosine triphosphate (ATP) level, free cytosolic [ATP], cell growth rate, and reactive oxygen species (ROS) levels. We conclude that the NDUFS4 subunit is of key importance in CI stabilization and that, due to the metabolic properties of the immortalized MEFs, NDUFS4 gene deletion has only modest effects at the live cell level. This article is part of a special issue entitled: 17th European Bioenergetics Conference (EBEC 2012).

Item does not contain fulltext, Mitochondrial complex I (CI) is a multi-subunit enzyme that forms the major entry point of nicotinamide adenine dinucleotide (NADH) electrons into the respiratory chain. Mutations in the NDUFS4 gene, encoding an accessory subunit of this complex, cause a Leigh-like phenotype in humans. To study the nature and penetrance of the CI defect in different tissues, we investigated the role of NDUFS4 in mice with fatal mitochondrial encephalomyopathy, caused by a systemic inactivation of the Ndufs4 gene. We report that the absence of NDUFS4 in different mouse tissues results in decreased activity and stability of CI. This CI instability leads to an increased disconnection of electron influx of the NADH dehydrogenase module from the holo-complex. However, the formation of respiratory supercomplexes still allows formation of active CI in these Ndufs4 knock-out mice. These results reveal the importance of these supramolecular interactions not only for stabilization but also for the assembly of CI, which becomes especially relevant in pathological conditions.

Radboud Universiteit Nijmegen, 27 maart 2012, Promotores : Smeitink, J.A.M., Brock, R.E. Co-promotores : Willems, P.H.G.M., Koopman, W.J., Contains fulltext : 108686.pdf (Publisher’s version ) (Open Access)

Item does not contain fulltext, Loss-of-function mutations in the gene encoding the mitochondrial PTEN-induced putative kinase 1 (PINK1) are a major cause of early-onset familial Parkinson's disease (PD). Recent studies have highlighted an important function for PINK1 in clearing depolarized mitochondria by mitophagy. However, the role of PINK1 in mitochondrial and cellular functioning in physiological conditions is still incompletely understood. Here, we investigate mitochondrial and cellular calcium (Ca(2+)) homeostasis in PINK1-knockdown and PINK1-knockout mouse cells, both in basal metabolic conditions and after physiological stimulation, using unbiased automated live single-cell imaging in combination with organelle-specific fluorescent probes. Our data reveal that depletion of PINK1 induces moderate fragmentation of the mitochondrial network, mitochondrial membrane depolarization and increased production of reactive oxygen species. This results in reduced uptake of Ca(2+) by mitochondria after physiological stimulation. As a consequence, cells with knockdown or knockout of PINK1 display impaired mitochondrial ATP synthesis, which is exacerbated under conditions of increased ATP demand, thereby affecting cytosolic Ca(2+) extrusion. The impairment in energy maintenance was confirmed in the brain of PINK1-knockout mice by in vivo bioluminescence imaging. Our findings demonstrate a key role for PINK1 in the regulation of mitochondrial homeostasis and energy metabolism under physiological conditions.

1 juni 2010, Contains fulltext : 89702.pdf (publisher's version ) (Closed access), Mitochondrial oxidative phosphorylation (OXPHOS) represents the final step in the conversion of nutrients into cellular energy. Genetic defects in the OXPHOS system have an incidence between 1:5,000 and 1:10,000 live births. Inherited isolated deficiency of the first complex (CI) of this system, a multisubunit assembly of 45 different proteins, occurs most frequently and originates from mutations in either the nuclear DNA, encoding 38 structural subunits and several assembly factors, or the mitochondrial DNA, encoding 7 structural subunits. The deficiency is associated with devastating multisystemic disorders, often affecting the brain, with onset in early childhood. There are currently no rational treatment strategies. Here, we present an overview of the genetic origins and cellular consequences of this deficiency and discuss how these insights might aid future development of treatment strategies.

Contains fulltext : 87452.pdf (publisher's version ) (Open Access), Virtually every mammalian cell contains mitochondria. These double-membrane organelles continuously change shape and position and contain the complete metabolic machinery for the oxidative conversion of pyruvate, fatty acids, and amino acids into ATP. Mitochondria are crucially involved in cellular Ca2+ and redox homeostasis and apoptosis induction. Maintenance of mitochondrial function and integrity requires an inside-negative potential difference across the mitochondrial inner membrane. This potential is sustained by the electron-transport chain (ETC). NADH:ubiquinone oxidoreductase or complex I (CI), the first and largest protein complex of the ETC, couples the oxidation of NADH to the reduction of ubiquinone. During this process, electrons can escape from CI and react with ambient oxygen to produce superoxide and derived reactive oxygen species (ROS). Depending on the balance between their production and removal by antioxidant systems, ROS may function as signaling molecules or induce damage to a variety of biomolecules or both. The latter ultimately leads to a loss of mitochondrial and cellular function and integrity. In this review, we discuss (a) the role of CI in mitochondrial functioning; (b) the composition, structure, and biogenesis of CI; (c) regulation of CI function; (d) the role of CI in ROS generation; and (e) adaptive responses to CI deficiency.

Contains fulltext : 80411.pdf (publisher's version ) (Closed access), Proper cell functioning requires precise coordination between mitochondrial ATP production and local energy demand. Ionic calcium (Ca(2+)) plays a central role in this coupling because it activates mitochondrial oxidative phosphorylation (OXPHOS) during hormonal and electrical cell stimulation. To determine how mitochondrial dysfunction affects cytosolic and mitochondrial Ca(2+)/ATP handling, we performed life-cell quantification of these parameters in fibroblast cell lines derived from healthy subjects and patients with isolated deficiency of the first OXPHOS complex (CI). In resting patient cells, CI deficiency was associated with a normal mitochondrial ([ATP](m)) and cytosolic ([ATP](c)) ATP concentration, a normal cytosolic Ca(2+) concentration ([Ca(2+)](c)), but a reduced Ca(2+) content of the endoplasmic reticulum (ER). Furthermore, cellular NAD(P)H levels were increased, mitochondrial membrane potential was slightly depolarized, reactive oxygen species (ROS) levels were elevated and mitochondrial shape was altered. Upon stimulation with bradykinin (Bk), the peak increases in [Ca(2+)](c), mitochondrial Ca(2+) concentration ([Ca(2+)](m)), [ATP](c) and [ATP](m) were reduced in patient cells. In agreement with these results, ATP-dependent Ca(2+) removal from the cytosol was slower. Here, we review the interconnection between cytosolic, endoplasmic reticular and mitochondrial Ca(2+) and ATP handling, and summarize our findings in patient fibroblasts in an integrative model.

Contains fulltext : 69376.pdf (publisher's version ) (Closed access), NADH:ubiquinone oxidoreductase or complex I is a large multisubunit assembly of the mitochondrial inner membrane that channels high-energy electrons from metabolic NADH into the electron transport chain (ETC). Its dysfunction is associated with a range of progressive neurological disorders, often characterized by a very early onset and short devastating course. To better understand the cytopathological mechanisms of these disorders, we use live cell luminometry and imaging microscopy of patient skin fibroblasts with mutations in nuclear-encoded subunits of the complex. Here, we present an overview of our recent work, showing that mitochondrial membrane potential, Ca(2+) handling and ATP production are to a variable extent impaired among a large cohort of patient fibroblast lines. From the results obtained, the picture emerges that a reduction in cellular complex I activity leads to a depolarization of the mitochondrial membrane potential, resulting in a decreased supply of mitochondrial ATP to the Ca(2+)-ATPases of the intracellular stores and thus to a reduced Ca(2+) content of these stores. As a consequence, the increase in cytosolic Ca(2+) concentration evoked by a Ca(2+) mobilizing stimulus is decreased, leading to a reduction in mitochondrial Ca(2+) accumulation and ensuing ATP production and thus to a hampered energization of stimulus-induced cytosolic processes.

Item does not contain fulltext, BACKGROUND: Shiga toxin (Stx) is the main pathogenic factor in the haemolytic-uraemic syndrome (HUS). Stx damages the renal endothelium, which leads to inflammation and coagulation. Endothelial heparan sulfate proteoglycans (HSPG), and heparan sulfate in particular, play an important role in the inflammatory process by acting as a ligand for l-selectin. Furthermore, leukocytes are able to interact with chemokines bound to HSPG (examples are IL-8, RANTES and MCP-1). This leads to an activation of integrins on leukocytes and results in more stable leukocyte-endothelial wall adhesion. In this study, we have evaluated the effect of a subtoxic dose of Stx1 and Stx2 on the HSPG and its role in adhesion of leukocytes. METHODS: Primary human umbilical venous endothelial cells (HUVEC) and primary human glomerular microvascular endothelial cells (GMVEC) were incubated for 24 h with a subtoxic dose of Stx1 or Stx2. Then, cells were treated with heparan sulfate-degrading enzyme heparitinase I or left untreated, followed by determination of binding leukocytes to endothelial cells in a parallel plate flow chamber. RESULTS: In both cell types, Stx increased the amount of firmly adherent leukocytes. After removal of endothelial heparan sulfate, the number of adhering leukocytes decreased. CONCLUSIONS: HSPG have a distinctive role in adhesion of leukocytes to endothelial cells stimulated by a subtoxic dose of Stx.

Contains fulltext : 70248.pdf (publisher's version ) (Closed access), Shiga toxins (Stx) are the virulence factors of enterohemorrhagic Escherichia coli O157:H7, a worldwide emerging diarrheal pathogen, which precipitates postdiarrheal hemolytic uremic syndrome, the leading cause of acute renal failure in children. In this study, we show that Stx2 triggered expression of fractalkine (FKN), a CX3C transmembrane chemokine, acting as both adhesion counterreceptor on endothelial cells and soluble chemoattractant. Stx2 caused in HUVEC expression of FKN mRNA and protein, which promoted leukocyte capture, ablated by Abs to either endothelial FKN or leukocyte CX3CR1 receptor. Exposure of human glomerular endothelial cells to Stx2 recapitulated its FKN-inducing activity and FKN-mediated leukocyte adhesion. Both processes required phosphorylation of Src-family protein tyrosine kinase and p38 MAPK in endothelial cells. Furthermore, they depended on nuclear import of NF-kappaB and other stress-responsive transcription factors. Inhibition of their nuclear import with the cell-penetrating SN50 peptide reduced FKN mRNA levels and FKN-mediated leukocyte capture by endothelial cells. Adenoviral overexpression of IkappaBalpha inhibited FKN mRNA up-regulation. The FKN-mediated responses to Stx2 were also dependent on AP-1. In mice, both virulence factors of Stx-producing E. coli, Stx and LPS, are required to elicit hemolytic uremic syndrome. In this study, FKN was detected within glomeruli of C57BL/6 mice injected with Stx2, and further increased after Stx2 plus LPS coadministration. This was associated with recruitment of CX3CR1-positive cells. Thus, in response to Stx2, FKN is induced playing an essential role in the promotion of leukocyte-endothelial cell interaction thereby potentially contributing to the renal microvascular dysfunction and thrombotic microangiopathy that underlie hemolytic uremic syndrome due to enterohemorrhagic E. coli O157:H7 infection.

Item does not contain fulltext, In mice with cisplatin-induced acute kidney injury, administration of bone marrow-derived mesenchymal stem cells (MSC) restores renal tubular structure and improves renal function, but the underlying mechanism is unclear. Here, we examined the process of kidney cell repair in co-culture experiments with MSC and cisplatin-injured proximal tubular epithelial cells (PTEC). Exposure of PTEC to cisplatin markedly reduced cell viability at 4 days, but co-culture with MSC provided a protective effect by promoting tubular cell proliferation. This effect was mediated by insulin-like growth factor-1 (IGF-1), highly expressed by MSC as mRNA and protein, since blocking the growth factor's function with a specific antibody attenuated cell proliferation of PTEC. Confirming this, knocking down IGF-1 expression in MSC by small interfering-RNA also resulted in a significant decrease in PTEC proliferation and increased apoptosis. Furthermore, in the murine model of cisplatin-induced kidney injury, administering IGF-1 gene-silenced MSC limited their protective effect on renal function and tubular structure. These findings indicate that MSC exert beneficial effects on tubular cell repair in acute kidney injury by producing the mitogenic and pro-survival factor IGF-1.