Direct Substrate Delivery into Mitochondrial-Fission Deficient Pancreatic Islets Rescues Insulin Secretion

In pancreatic beta cells, mitochondrial bioenergetics control glucose-stimulated insulin secretion (GSIS). Mitochondrial dynamics are generally associated with quality control, maintaining the functionality of bioenergetics. By acute pharmacological inhibition of mitochondrial fission protein Drp1, we here demonstrate that mitochondrial fission is necessary for GSIS in mouse and human islets. We confirm that genetic silencing of Drp1 increases mitochondrial proton leak in MIN6 cells. However, our comprehensive analysis of pancreatic islet bioenergetics reveals that Drp1 does not control insulin secretion via its effect on proton leak but instead via modulation of glucose-fuelled respiration. Notably, pyruvate fully rescues the impaired insulin secretion of fission-deficient beta cells, demonstrating that defective mitochondrial dynamics solely impact substrate supply upstream of oxidative phosphorylation. The present findings provide novel insights in how mitochondrial dysfunction may cause pancreatic beta cell failure. In addition, the results will stimulate new thinking in the intersecting fields of mitochondrial dynamics and bioenergetics, as treatment of defective dynamics in mitochondrial diseases appears to be possible by improving metabolism upstream of mitochondria

Intra-Decadal Increase in Globally-Spread Magallana gigas in Southern California Estuaries

Introduction and establishment of non-indigenous species (NIS) has been accelerated on a global scale by climate change. NIS Magallana gigas\u27 (formerly Crassostrea gigas\u27) global spread over the past several decades has been linked to warming waters, specifically during summer months, raising the specter of more spread due to predicted warming. We tracked changes in density and size distribution of M. gigas in two southern California, USA bays over the decade spanning 2010-2020 using randomly placed quadrats across multiple intertidal habitats (e.g., cobble, seawalls, riprap) and documented density increases by 2.2 to 32.8 times at 7 of the 8 sites surveyed across the two bays. These increases in density were coincident with 2-4° C increases in median monthly seawater temperature during summer months, consistent with global spread of M. gigas elsewhere. Size frequency distribution data, with all size classes represented across sites, suggest now-regular recruitment of M. gigas. Our data provide a baseline against which to compare future changes in density and abundance of a globally-spread NIS of significant concern

Outcomes with daptomycin in the treatment of Staphylococcus aureus infections with a range of vancomycin MICs

Staphylococcus aureus suggest the use of alternative agents when vancomycin MIC values are ≥2 mg/L. This study examines the outcome of patients treated with daptomycin for S. aureus infections with documented vancomycin MICs. Patients and methods: All patients with skin, bacteraemia and endocarditis infections due to S. aureus with vancomycin MIC values in CORE 2005–08, a retrospective, multicentre, observational registry, were studied. The outcome (cure, improved, failure or non-evaluable) was the investigator assessment at the end of dapto-mycin therapy. Success was defined as cure or improved. Results: Five hundred and forty-seven clinically evaluable patients were identified with discrete vancomycin MIC values [MIC,2 mg/L: 451 (82%); MIC ≥2 mg/L: 96 (18%)]. The vancomycin MIC groups were well matched for patient characteristics, types of infections, first-line daptomycin use (19%) and prior vancomycin use (58%). Clinical success was reported in 94 % of patients. No differences were detected in the daptomycin success rate by the vancomycin MIC group overall or by the infection type. A multivariate logistic regression also failed to identify vancomycin MIC as a predictor of daptomycin failure. Adverse event (AE) rates were not differ-ent when analysed by MIC group; both groups had 17 % of patients with one AE. Conclusions: In this diverse population, daptomycin was associated with similar outcomes for patients, regard-less of whether the vancomycin MIC was categorized as,2 or ≥2 mg/L. Further studies are warranted

Selenium Utilization by GPX4 Is Required to Prevent Hydroperoxide-Induced Ferroptosis

open24siSelenoproteins are rare proteins among all kingdoms of life containing the 21st amino acid, selenocysteine. Selenocysteine resembles cysteine, differing only by the substitution of selenium for sulfur. Yet the actual advantage of selenolate- versus thiolate-based catalysis has remained enigmatic, as most of the known selenoproteins also exist as cysteine-containing homologs. Here, we demonstrate that selenolate-based catalysis of the essential mammalian selenoprotein GPX4 is unexpectedly dispensable for normal embryogenesis. Yet the survival of a specific type of interneurons emerges to exclusively depend on selenocysteine-containing GPX4, thereby preventing fatal epileptic seizures. Mechanistically, selenocysteine utilization by GPX4 confers exquisite resistance to irreversible overoxidation as cells expressing a cysteine variant are highly sensitive toward peroxide-induced ferroptosis. Remarkably, concomitant deletion of all selenoproteins in Gpx4cys/cys cells revealed that selenoproteins are dispensable for cell viability provided partial GPX4 activity is retained. Conclusively, 200 years after its discovery, a specific and indispensable role for selenium is provided.openIngold, Irina; Berndt, Carsten; Schmitt, Sabine; Doll, Sebastian; Poschmann, Gereon; Buday, Katalin; Roveri, Antonella; Peng, Xiaoxiao; Porto Freitas, Florencio; Seibt, Tobias; Mehr, Lisa; Aichler, Michaela; Walch, Axel; Lamp, Daniel; Jastroch, Martin; Miyamoto, Sayuri; Wurst, Wolfgang; Ursini, Fulvio; Arnér, Elias S J; Fradejas-Villar, Noelia; Schweizer, Ulrich; Zischka, Hans; Friedmann Angeli, José Pedro; Conrad, MarcusIngold, Irina; Berndt, Carsten; Schmitt, Sabine; Doll, Sebastian; Poschmann, Gereon; Buday, Katalin; Roveri, Antonella; Peng, Xiaoxiao; Porto Freitas, Florencio; Seibt, Tobias; Mehr, Lisa; Aichler, Michaela; Walch, Axel; Lamp, Daniel; Jastroch, Martin; Miyamoto, Sayuri; Wurst, Wolfgang; Ursini, Fulvio; Arnér, Elias S J; Fradejas-Villar, Noelia; Schweizer, Ulrich; Zischka, Hans; Friedmann Angeli, José Pedro; Conrad, Marcu

Neonatal Astrocyte Damage Is Sufficient to Trigger Progressive Striatal Degeneration in a Rat Model of Glutaric Acidemia-I

BACKGROUND: We have investigated whether an acute metabolic damage to astrocytes during the neonatal period may critically disrupt subsequent brain development, leading to neurodevelopmental disorders. Astrocytes are vulnerable to glutaric acid (GA), a dicarboxylic acid that accumulates in millimolar concentrations in Glutaric Acidemia I (GA-I), an inherited neurometabolic childhood disease characterized by degeneration of striatal neurons. While GA induces astrocyte mitochondrial dysfunction, oxidative stress and subsequent increased proliferation, it is presently unknown whether such astrocytic dysfunction is sufficient to trigger striatal neuronal loss. METHODOLOGY/PRINCIPAL FINDINGS: A single intracerebroventricular dose of GA was administered to rat pups at postnatal day 0 (P0) to induce an acute, transient rise of GA levels in the central nervous system (CNS). GA administration potently elicited proliferation of astrocytes expressing S100β followed by GFAP astrocytosis and nitrotyrosine staining lasting until P45. Remarkably, GA did not induce acute neuronal loss assessed by FluoroJade C and NeuN cell count. Instead, neuronal death appeared several days after GA treatment and progressively increased until P45, suggesting a delayed onset of striatal degeneration. The axonal bundles perforating the striatum were disorganized following GA administration. In cell cultures, GA did not affect survival of either striatal astrocytes or neurons, even at high concentrations. However, astrocytes activated by a short exposure to GA caused neuronal death through the production of soluble factors. Iron porphyrin antioxidants prevented GA-induced astrocyte proliferation and striatal degeneration in vivo, as well as astrocyte-mediated neuronal loss in vitro. CONCLUSIONS/SIGNIFICANCE: Taken together, these results indicate that a transient metabolic insult with GA induces long lasting phenotypic changes in astrocytes that cause them to promote striatal neuronal death. Pharmacological protection of astrocytes with antioxidants during encephalopatic crisis may prevent astrocyte dysfunction and the ineluctable progression of disease in children with GA-I

Treatment of complicated skin and soft-tissue infections caused by resistant bacteria: value of linezolid, tigecycline, daptomycin and vancomycin

Antibiotic-resistant organisms causing both hospital-and community-acquired complicated skin and soft-tissue infections (cSSTI) are increasingly reported. A substantial medical and economical burden associated with MRSA colonisation or infection has been documented. The number of currently available appropriate antimicrobial agents is limited. Good quality randomised, controlled clinical trial data on antibiotic efficacy and safety is available for cSSTI caused by MRSA. Linezolid, tigecycline, daptomycin and vancomycin showed efficacy and safety in MRSA-caused cSSTI. None of these drugs showed significant superiority in terms of clinical cure and eradication rates. To date, linezolid offers by far the greatest number of patients included in controlled trials with a strong tendency of superiority over vancomycin in terms of eradication and clinical success

Combined measurements of Higgs boson couplings in proton- proton collisions at v s=13TeV

Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton-proton collision data set recorded with the CMS detector in 2016 at fb-1. The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a W or Z boson, or a top quark-antiquark pair) and the following decay modes: H, ZZ, WW, , bb, and . Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be =1.17 +/- 0.10, assuming a Higgs boson mass of 125.09. Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.Peer reviewe