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Objective: The indications for and approaches to extracapsular dissection for parotid gland benign tumours are debated in the literature. This study retrospectively evaluates a single site's short- and long-term results with a standardised extracapsular dissection approach to benign parotid tumours., Methods: A retrospective review of a single institution's records identified cases with extracapsular dissection as the primary surgery for non-recurrent benign parotid tumours. A total of 194 eligible patients were identified (124 women and 70 men, age 47.75 ± 15.62 years). Pre-, intra- and post-surgical data were reviewed for complications and recurrences., Results: Histology reported pleomorphic adenoma in 165 patients, Warthin's tumour in 28 patients and both in one patient. Mean follow up was 36 ± 16 months (range, 12-84 months). The incidences of complications following extracapsular dissection were temporary ( n = 13) and permanent ( n = 0) facial nerve dysfunction, Frey's syndrome ( n = 1)) and recurrences ( n = 5). These rates align with prior literature., Conclusion: This case series shows how a standardised approach to extracapsular dissection for benign parotid tumours yields favourable results, supporting a progressive change of strategy towards reduced invasiveness.

Facial paralysis decreases eye protection mechanisms leading to ocular problems up to corneal ulceration, and blindness. This study aimed to evaluate the outcomes of periocular procedures for recent facial paralysis. Medical records of patients with unilateral recent complete facial palsy who did periocular procedures at the Maxillofacial Surgery Department of San Paolo Hospital (Milan, Italy) between April 2018 and November 2021 were retrospectively reviewed. 26 patients were included. All patients were evaluated 4 months after surgery. The first group included 9 patients who underwent upper eye lid lipofilling and midface suspension with fascia lata graft; they had no ocular dryness symptoms and no need for eye protection measures in 33.3% of cases, significant reduction of ocular symptoms and need for eye protection measures in 66.6% of patient, 0-2 mm lagophthalmos in 66.6% and 3-4 mm lagophthalmos in 33.3%. The second group of 17 patients who underwent upper eyelid lipofilling, midface suspension with fascia lata graft and lateral tarsorrhaphy, had no ocular dryness symptoms and no need for eye protection measures in 17.6% of patient, significant reduction of ocular symptoms and need for eye protection measures in 76.4% of patient, 0-2 mm lagophthalmos in 70.5%, 3-4 mm lagophthalmos in 23.5% and one patient 5,8%had 8 mm lagophthalmos and persistent symptoms. No ocular complication, cosmetic complain or donner site morbidity were reported. Upper eyelid lipofilling, midface suspension with fascia lata graft and lateral tarsorrhaphy decrease ocular dryness symptoms and need for eye protection measures and improve lagophthalmos: the association of the reinnervation with these complementary techniques is therefore highly recommended in order to immediately protect the eye., Competing Interests: Declaration of competing interest None., (Copyright © 2023 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Context: Several case reports of Graves' disease (GD) occurrence after COVID-19 vaccination that are possibly related to the autoimmune syndrome induced by adjuvants (ASIA) were published recently., Objective: The aim of our study was to evaluate possible distinctive features in the presentation and clinical course of patients with GD occurring early (within 4 weeks) after COVID-19 vaccination who attended our Endocrine Unit in 2021., Methods: Patients with a first episode of GD attending a tertiary endocrine center between January 1, 2021, and December 31, 2021, were included., Results: Sixty-four patients with a first episode of GD were seen in 2021: 20 (31.2%) of them had onset within 4 weeks following vaccine administration. Compared with the other 44 patients, the 20 patients with postvaccine early-onset (PoVEO) GD were older (median age 51 years vs 35 years, P = .003) and more likely to be male (40.0% vs 13.6%, P = .018). At diagnosis, the biochemical and immune profiles were similar between the 2 groups. However, at 3 months after starting methimazole, patients with PoVEO GD had significantly lower thyrotropin receptor antibody titer and were taking lower doses of methimazole than the other patients with GD. None in the PoVEO group had sustained free triiodothyronine elevation., Conclusion: This relatively large series suggests that in 2021 PoVEO GD may be a new nosologic entity representing one-third of patients evaluated for new-onset GD in our center. Distinctive features included older age at onset, higher male prevalence, and a better initial biochemical and immunologic response to treatment. Further studies are warranted to clinically and biochemically differentiate these cases from sporadically occurring GD., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: The aim of this work is to formulate recommendations based on global expert consensus to guide the surgical community on the safe resumption of surgical and endoscopic activities., Background: The COVID-19 pandemic has caused marked disruptions in the delivery of surgical care worldwide. A thoughtful, structured approach to resuming surgical services is necessary as the impact of COVID-19 becomes better controlled. The Coronavirus Global Surgical Collaborative sought to formulate, through rigorous scientific methodology, consensus-based recommendations in collaboration with a multidisciplinary group of international experts and policymakers., Methods: Recommendations were developed following a Delphi process. Domain topics were formulated and subsequently subdivided into questions pertinent to different aspects of surgical care in the COVID-19 crisis. Forty-four experts from 15 countries across 4 continents drafted statements based on the specific questions. Anonymous Delphi voting on the statements was performed in 2 rounds, as well as in a telepresence meeting., Results: One hundred statements were formulated across 10 domains. The statements addressed terminology, impact on procedural services, patient/staff safety, managing a backlog of surgeries, methods to restart and sustain surgical services, education, and research. Eighty-three of the statements were approved during the first round of Delphi voting, and 11 during the second round. A final telepresence meeting and discussion yielded acceptance of 5 other statements., Conclusions: The Delphi process resulted in 99 recommendations. These consensus statements provide expert guidance, based on scientific methodology, for the safe resumption of surgical activities during the COVID-19 pandemic., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Using molecular, biochemical, and untargeted stable isotope tracing approaches, we identify a previously unappreciated glutamine-derived α-ketoglutarate (αKG) energy-generating anaplerotic flux to be critical in mitochondrial DNA (mtDNA) mutant cells that harbor human disease-associated oxidative phosphorylation defects. Stimulating this flux with αKG supplementation enables the survival of diverse mtDNA mutant cells under otherwise lethal obligatory oxidative conditions. Strikingly, we demonstrate that when residual mitochondrial respiration in mtDNA mutant cells exceeds 45% of control levels, αKG oxidative flux prevails over reductive carboxylation. Furthermore, in a mouse model of mitochondrial myopathy, we show that increased oxidative αKG flux in muscle arises from enhanced alanine synthesis and release into blood, concomitant with accelerated amino acid catabolism from protein breakdown. Importantly, in this mouse model of mitochondriopathy, muscle amino acid imbalance is normalized by αKG supplementation. Taken together, our findings provide a rationale for αKG supplementation as a therapeutic strategy for mitochondrial myopathies., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Mutations in coiled-coil-helix-coiled-coil-helix-domain containing 10 (CHCHD10), a mitochondrial twin CX9C protein whose function is still unknown, cause myopathy, motor neuron disease, frontotemporal dementia, and Parkinson's disease. Here, we investigate CHCHD10 topology and its protein interactome, as well as the effects of CHCHD10 depletion or expression of disease-associated mutations in wild-type cells. We find that CHCHD10 associates with membranes in the mitochondrial intermembrane space, where it interacts with a closely related protein, CHCHD2. Furthermore, both CHCHD10 and CHCHD2 interact with p32/GC1QR, a protein with various intra and extra-mitochondrial functions. CHCHD10 and CHCHD2 have short half-lives, suggesting regulatory rather than structural functions. Cell lines with CHCHD10 knockdown do not display bioenergetic defects, but, unexpectedly, accumulate excessive intramitochondrial iron. In mice, CHCHD10 is expressed in many tissues, most abundantly in heart, skeletal muscle, liver, and in specific CNS regions, notably the dopaminergic neurons of the substantia nigra and spinal cord neurons, which is consistent with the pathology associated with CHCHD10 mutations. Homozygote CHCHD10 knockout mice are viable, have no gross phenotypes, no bioenergetic defects or ultrastructural mitochondrial abnormalities in brain, heart or skeletal muscle, indicating that functional redundancy or compensatory mechanisms for CHCHD10 loss occur in vivo. Instead, cells expressing S59L or R15L mutant versions of CHCHD10, but not WT, have impaired mitochondrial energy metabolism. Taken together, the evidence obtained from our in vitro and in vivo studies suggest that CHCHD10 mutants cause disease through a gain of toxic function mechanism, rather than a loss of function., (© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

cAMP regulates a wide variety of physiological functions in mammals. This single second messenger can regulate multiple, seemingly disparate functions within independently regulated cell compartments. We have previously identified one such compartment inside the matrix of the mitochondria, where soluble adenylyl cyclase (sAC) regulates oxidative phosphorylation (OXPHOS). We now show that sAC knockout fibroblasts have a defect in OXPHOS activity and attempt to compensate for this defect by increasing OXPHOS proteins. Importantly, sAC knockout cells also exhibit decreased probability of endoplasmic reticulum (ER) Ca 2+ release associated with diminished phosphorylation of the inositol 3-phosphate receptor. Restoring sAC expression exclusively in the mitochondrial matrix rescues OXPHOS activity and reduces mitochondrial biogenesis, indicating that these phenotypes are regulated by intramitochondrial sAC. In contrast, Ca 2+ release from the ER is only rescued when sAC expression is restored throughout the cell. Thus, we show that functionally distinct, sAC-defined, intracellular cAMP signaling domains regulate metabolism and Ca 2+ signaling., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2017. Published by The Company of Biologists Ltd.)

Background: Mitochondrial dysfunction has been linked to the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Functional studies of mitochondrial bioenergetics have focused mostly on superoxide dismutase 1 (SOD1) mutants, and showed that mutant human SOD1 impairs mitochondrial oxidative phosphorylation, calcium homeostasis, and dynamics. However, recent reports have indicated that alterations in transactivation response element DNA-binding protein 43 (TDP-43) can also lead to defects of mitochondrial morphology and dynamics. Furthermore, it was proposed that TDP-43 mutations cause oxidative phosphorylation impairment associated with respiratory chain defects and that these effects were caused by mitochondrial localization of the mutant protein. Here, we investigated the presence of bioenergetic defects in the brain of transgenic mice expressing human mutant TDP-43 (TDP-43 A315T mice), patient derived fibroblasts, and human cells expressing mutant forms of TDP-43., Methods: In the brain of TDP-43 A315T mice, TDP-43 mutant fibroblasts, and cells expressing mutant TDP-43, we tested several bioenergetics parameters, including mitochondrial respiration, ATP synthesis, and calcium handling. Differences between mutant and control samples were evaluated by student t-test or by ANOVA, followed by Bonferroni correction, when more than two groups were compared. Mitochondrial localization of TDP-43 was investigated by immunocytochemistry in fibroblasts and by subcellular fractionation and western blot of mitochondrial fractions in mouse brain., Results: We did not observe defects in any of the mitochondrial bioenergetic functions that were tested in TDP-43 mutants. We detected a small amount of TDP-43 A315T peripherally associated with brain mitochondria. However, there was no correlation between TDP-43 associated with mitochondria and respiratory chain dysfunction. In addition, we observed increased calcium uptake in mitochondria from TDP-43 A315T mouse brain and cells expressing A315T mutant TDP-43., Conclusions: While alterations of mitochondrial morphology and dynamics in TDP-43 mutant neurons are well established, the present study did not demonstrate oxidative phosphorylation defects in TDP-43 mutants, in vitro and in vivo. On the other hand, the increase in mitochondrial calcium uptake in A315T TDP-43 mutants was an intriguing finding, which needs to be investigated further to understand its mechanisms and potential pathogenic implications.

The prototypical second messenger cAMP regulates a wide variety of physiological processes. It can simultaneously mediate diverse functions by acting locally in independently regulated microdomains. In mammalian cells, two types of adenylyl cyclase generate cAMP: G-protein-regulated transmembrane adenylyl cyclases and bicarbonate-, calcium- and ATP-regulated soluble adenylyl cyclase (sAC). Because each type of cyclase regulates distinct microdomains, methods to distinguish between them are needed to understand cAMP signaling. We developed a mass-spectrometry-based adenylyl cyclase assay, which we used to identify a new sAC-specific inhibitor, LRE1. LRE1 bound to the bicarbonate activator binding site and inhibited sAC via a unique allosteric mechanism. LRE1 prevented sAC-dependent processes in cellular and physiological systems, and it will facilitate exploration of the therapeutic potential of sAC inhibition., Competing Interests: Drs. Buck, Levin and Zippin own equity interest in CEP Biotech which has licensed commercialization of a panel of monoclonal antibodies directed against sAC. All other authors declare that they have no conflicts of interest with the contents of this article.

Mitochondrial Complex II is a key mitochondrial enzyme connecting the tricarboxylic acid (TCA) cycle and the electron transport chain. Studies of complex II are clinically important since new roles for this enzyme have recently emerged in cell signalling, cancer biology, immune response and neurodegeneration. Oxaloacetate (OAA) is an intermediate of the TCA cycle and at the same time is an inhibitor of complex II with high affinity (Kd~10(-8)M). Whether or not OAA inhibition of complex II is a physiologically relevant process is a significant, but still controversial topic. We found that complex II from mouse heart and brain tissue has similar affinity to OAA and that only a fraction of the enzyme in isolated mitochondrial membranes (30.2±6.0% and 56.4±5.6% in the heart and brain, respectively) is in the free, active form. Since OAA could bind to complex II during isolation, we established a novel approach to deplete OAA in the homogenates at the early stages of isolation. In heart, this treatment significantly increased the fraction of free enzyme, indicating that OAA binds to complex II during isolation. In brain the OAA-depleting system did not significantly change the amount of free enzyme, indicating that a large fraction of complex II is already in the OAA-bound inactive form. Furthermore, short-term ischemia resulted in a dramatic decline of OAA in tissues, but it did not change the amount of free complex II. Our data show that in brain OAA is an endogenous effector of complex II, potentially capable of modulating the activity of the enzyme., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

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-α/SIRT1/mTOR levels. Survival of CI-inhibited cells was strictly glucose-dependent and accompanied by increased AMPK-α phosphorylation, which occurred without changes in ATP or cytosolic calcium levels. Conversely, cells devoid of AMPK-α 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-α. This response avoids cell death by suppressing energy crisis, oxidative stress induction and substantial mitochondrial depolarization., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The soluble adenylyl cyclase (sAC) catalyzes the conversion of ATP into cyclic AMP (cAMP). Recent studies have shed new light on the role of sAC localized in mitochondria and its product cAMP, which drives mitochondrial protein phosphorylation and regulation of the oxidative phosphorylation system and other metabolic enzymes, presumably through the activation of intra-mitochondrial PKA. In this review article, we summarize recent findings on mitochondrial sAC activation by bicarbonate (HCO(3)(-)) and calcium (Ca²⁺) and the effects on mitochondrial metabolism. We also discuss putative mechanisms whereby sAC-mediated mitochondrial protein phosphorylation regulates mitochondrial metabolism. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Energy metabolism could influence amyotrophic lateral sclerosis (ALS) and progressive lateral sclerosis (PLS) pathogenesis and the response to therapy. We developed a novel assay to simultaneously assess mitochondrial content and membrane potential in patients' skin fibroblasts. In ALS and PLS fibroblasts, membrane potential was increased and mitochondrial content decreased, relative to healthy controls. In ALS higher mitochondrial membrane potential correlated with age at diagnosis, and in PLS it correlated with disease severity. These unprecedented findings in ALS and PLS fibroblasts could shed new light onto disease pathogenesis and help in developing biomarkers to predict disease evolution and the individual response to therapy in motor neuron diseases., (© 2014 American Neurological Association.)

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., (Copyright © 2012 © Elsevier B.V. and Mitochondria Research Society. All rights reserved. Published by Elsevier B.V. All rights reserved.)

Phosphorylation of mitochondrial proteins has emerged as a major regulatory mechanism for metabolic adaptation. cAMP signaling and PKA phosphorylation of mitochondrial proteins have just started to be investigated, and the presence of cAMP-generating enzymes and PKA inside mitochondria is still controversial. Here, we discuss the role of cAMP in regulating mitochondrial bioenergetics through protein phosphorylation and the evidence for soluble adenylyl cyclase as the source of cAMP inside mitochondria.

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.

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)., (Copyright © 2012 Elsevier B.V. All rights reserved.)

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.

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., (Copyright © 2011 Elsevier B.V. and Mitochondria Research Society. All rights reserved.)

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.

The X-ray source M33 X-7 in the nearby galaxy Messier 33 is among the most massive X-ray binary stellar systems known, hosting a rapidly spinning, 15.65M(⊙) black hole orbiting an underluminous, 70M(⊙) main-sequence companion in a slightly eccentric 3.45-day orbit (M(⊙), solar mass). Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-ray luminosity, the star's underluminosity, the black hole's spin and the orbital eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report simulations of evolutionary tracks which reveal that if M33 X-7 started as a primary body of 85M(⊙)-99M(⊙) and a secondary body of 28M(⊙)-32M(⊙), in a 2.8-3.1-d orbit, its observed properties can be consistently explained. In this model, the main-sequence primary transfers part of its envelope to the secondary and loses the rest in a wind; it ends its life as a ∼16M(⊙) helium star with an iron-nickel core that collapses to a black hole (with or without an accompanying supernova). The release of binding energy, and possibly collapse asymmetries, 'kick' the nascent black hole into an eccentric orbit. Wind accretion explains the X-ray luminosity, and the black-hole spin can be natal.

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.

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., ((c) 2010 Wiley-Liss, Inc.)

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.

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.

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.

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.

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.

The cyclin-dependent kinase (CDK) inhibitor p21CDKN1A is known to induce cell cycle arrest by inhibiting CDK activity and by interfering with DNA replication through binding to proliferating cell nuclear antigen. Although the molecular mechanisms have been elucidated, the temporal dynamics, as well as the intracellular sites of the activity of p21 bound to cyclin/CDK complexes during cell cycle arrest, have not been fully investigated. In this study we have induced the expression of p21CDKN1A fused to green fluorescent protein (GFP) in HeLa cells, in order to visualize the intracellular localization of the inhibitor during the cell cycle arrest. We show that p21-GFP is preferentially expressed in association with cyclin E in cells arrested in G1 phase, and with cyclin A more than with cyclin B1 in cells arrested in the G2/M compartment. In addition, we show for the first time that p21-GFP colocalizes with cyclin E in the nucleolus of HeLa cells during the G1 phase arrest.

We studied the relationships between magnetic resonance imaging (MRI) and the Luria-Nebraska Neuropsychological Battery (LNNB) in 64 patients with relapsing-remitting multiple sclerosis (MS). MRI films were scored according to arbitrary descriptive criteria designed to emphasize patterns of alterations. Five groups were created: group 1 and 2 had typical discrete white matter lesions, group 3 had confluent lesions, group 4 had large discrete lesions and group 5 had only few small lesions. In addition, groups 2 and 3 had evidence of parenchymal atrophy. Groups 2 and 3 were the most impaired on the LNNB, but none of these patients was actually demented. Groups 1 and 5 were globally intact in spite of very different mean age and MRI pattern. Group 4 was composed of younger subjects with a shorter disease duration; they showed mild loss of attentive and abstracting abilities. We suggest that since their MRI was showing greater signs of local biological activity their mental deficits may be a transitory condition capable of two distinct outcomes: a favorable one as in groups 1 and 5, and a slowly progressive one associated with loss of brain tissue as in groups 2 and 3.

Thirty-three patients have been treated with balloon catheters since 1978. Debrun's detachable balloons were used in 31 and a Fogarty catheter in the other two. Problems were encountered from the introduction of the catheter to the detachment of the balloon. We have treated 21 fistulas between the internal carotid and cavernous sinus, 3 fistulas between the external carotid and jugular vein, 2 mixed fistulas between internal and external carotid and cavernous sinus, 2 vertebral fistulas and 5 intracavernous aneurysms. Delayed angiographic control has shown that the arterial axis remained patent in a high percentage of cases and that the formation of an asymptomatic pseudo-aneurysmal sac within the cavernous sinus is the rule. Long-term clinical follow-up has confirmed the angiographic results. In two patients neurological complications led to the patients' death.

Three patients with angiographic and CT findings of cerebral sinovenous occlusion are described. Filling defects within the venous pathways are well demonstrated by angiography. Some of the most characteristic CR signs are here described. Full evaluation, including the clinical history, angiography and computed tomography is essential.

During a 4 year period, 48 patients were treated with balloon catheters. There were 39 fistulas and nine aneurysms. Detachable balloons with a modified Debrun technique were used in 37 patients. Different kinds of technical problems were encountered. The arterial axis remained patent in 29 of the 37 fistulas; in the two mixed internal and external carotid-cavernous sinus fistulas, combined embolization with dura, isobutyl cyanoacrylate, and detachable balloon was used. In six of the nine aneurysms the arterial axis was occluded with a detachable balloon. In three of 48 patients, severe neurologic complications resulted in death.

Forty patients with symptoms and signs of radicular disease or spinal cord involvement secondary to cervical spondylosis were studied with myelography (using nonionic water-soluble contrast medium) followed by computed tomographic (CT) myelography. In 17 patients CT was also performed before myelography. CT myelography adds useful information to the myelographic findings. Cord compression is better evaluated and osteophytes can be differentiated from disk herniation. Plain CT can demonstrate a herniated disk but with less accuracy than CT myelography. Cord and root compression are not seen directly on plain CT; for this reason myelography should be the first procedure in patients with myelopathy or myeloradiculopathy, which may be followed by CT myelography.

To evaluate the influence of age on carotid atheroma we reviewed the angiographic findings in 120 patients with reversible ischemic attacks. The prevalence and severity of atherosclerotic lesions increased significantly with age, and this difference persisted after adjusting for hypertension. These results may at least partly explain the poor long term prognosis for elderly subjects with reversible ischemic attacks, and underscore the importance of taking age into account when relating clinical and angiographic findings in patients with cerebrovascular ischemia.

A simple fistula between the external carotid artery and the internal jugular vein was treated for the first time using Debrun's technique with a detachable balloon catheter. The nature of the fistulous connection makes the release of the balloon inflated with silicone completely harmless. The occlusion of the fistula, while maintaining the patency of the remaining branches of the external carotid artery, proves this technique to be the most appropriate for the treatment of arteriovenous fistulae in the neck.