Staphylococcus epidermidis biofilm formation is responsible for the persistence of orthopedic implant infections. Previous studies have shown that exposure of S. epidermidis biofilms to sub-MICs of ...antibiotics induced an increased level of biofilm persistence. BODIPY FL-vancomycin (a fluorescent vancomycin conjugate) and confocal microscopy were used to show that the penetration of vancomycin through sub-MIC-vancomycin-treated S. epidermidis biofilms was impeded compared to that of control, untreated biofilms. Further experiments showed an increase in the extracellular DNA (eDNA) concentration in biofilms preexposed to sub-MIC vancomycin, suggesting a potential role for eDNA in the hindrance of vancomycin activity. Exogenously added, S. epidermidis DNA increased the planktonic vancomycin MIC and protected biofilm cells from lethal vancomycin concentrations. Finally, isothermal titration calorimetry (ITC) revealed that the binding constant of DNA and vancomycin was 100-fold higher than the previously reported binding constant of vancomycin and its intended cellular d-Ala-d-Ala peptide target. This study provides an explanation of the eDNA-based mechanism of antibiotic tolerance in sub-MIC-vancomycin-treated S. epidermidis biofilms, which might be an important factor for the persistence of biofilm infections.
Amyotrophic Lateral Sclerosis (ALS) is a fatal multisystem neurodegenerative disease, characterized by a loss in motor function. ALS is genetically diverse, with mutations in genes ranging from those ...regulating RNA metabolism, like TAR DNA-binding protein (TDP-43) and Fused in sarcoma (FUS), to those that act to maintain cellular redox homeostasis, like superoxide dismutase 1 (SOD1). Although varied in genetic origin, pathogenic and clinical commonalities are clearly evident between cases of ALS. Defects in mitochondria is one such common pathology, thought to occur prior to, rather than as a consequence of symptom onset, making these organelles a promising therapeutic target for ALS, as well as other neurodegenerative diseases. Depending on the homeostatic needs of neurons throughout life, mitochondria are normally shuttled to different subcellular compartments to regulate metabolite and energy production, lipid metabolism, and buffer calcium. While originally considered a motor neuron disease due to the dramatic loss in motor function accompanied by motor neuron cell death in ALS patients, many studies have now implicated non-motor neurons and glial cells alike. Defects in non-motor neuron cell types often preceed motor neuron death suggesting their dysfunction may initiate and/or facilitate the decline in motor neuron health. Here, we investigate mitochondria in a Drosophila Sod1 knock-in model of ALS. In depth, in vivo, examination reveals mitochondrial dysfunction evident prior to onset of motor neuron degeneration. Genetically encoded redox biosensors identify a general disruption in the electron transport chain (ETC). Compartment specific abnormalities in mitochondrial morphology is observed in diseased sensory neurons, accompanied by no apparent defects in the axonal transport machinery, but instead an increase in mitophagy in synaptic regions. The decrease in networked mitochondria at the synapse is reversed upon downregulation of the pro-fission factor Drp1. Furthermore, altered expression of specific OXPHOS subunits reverses ALS-associated defects in mitochondrial morphology and function.
•Mitochondrial defects in sensory neurons contribute to amyotrophic lateral sclerosis.•Neuron-specific defects in mitochondrial morphology, mitophagy, and oxidative phosphorylation in Drosophila SOD1-ALS model•Downregulation of pro-fission factor, Drp1, restores networked mitochondria at synapse•ALS-associated mitochondrial defects reversed by altered expression of individual OXPHOS subunits
New Zealand has extensive alpine and subalpine habitats where, together with some lowland sites, insects are exposed to subzero temperatures. Studies of cold tolerance in New Zealand insects have ...centred on an alpine weta (Hemideina maori), which is the world's largest freezing tolerant insect, and an alpine cockroach (Celatoblatta quinquemaculata). Both of these insects are moderately freezing tolerant and have ice nucleating agents in their haemolymph and guts. There is some evidence for the survival of intracellular ice formation in the isolated gut tissue of C. quinquemaculata. Trehalose is a suggested cryoprotectant in both H. maori and C. quinquemaculata whilst proline also provides this role in H. maori. Cells and tissues of both insects maintain viability and physiological function during freezing to moderately low temperatures but viability declines at lower temperatures, the most vulnerable tissue presumably setting the limit to the survival of the animal. Antifreeze proteins are found in the gut tissue of C. quinquemaculata and may protect this tissue when freezing occurs in the gut. Several other New Zealand insects are also moderately freezing tolerant and the apparent dominance of this cold tolerance strategy in the New Zealand fauna may reflect the relatively mild climate but unpredictable exposure to subzero temperatures that is typical of many Southern Hemisphere environments.
Hepatoblastomas are the most frequent malignant liver tumors of childhood. A high frequency of activating β-catenin mutations in hepatoblastomas indicates that the Wnt signaling pathway plays an ...important role in the development of this
embryonic neoplasm. Stabilization of β-catenin leads to an increased formation of nuclear β-catenin-T-cell factor complexes
and altered expression of Wnt-inducible target genes. In this study, we analyzed the mRNA expression levels of nine Wnt genes,
including c-JUN, c-MYC, CYCLIN D1, FRA-1, NKD-1, ITF-2, MMP-7, uPAR , and β-TRCP , by competitive reverse transcription-PCR. We analyzed 23 hepatoblastoma biopsies for which matching liver tissue was available,
6 hepatoblastoma cell lines, and 3 human fetal liver samples. β-TRCP and NKD-1 were highly expressed in all hepatoblastoma samples, independent of the β-catenin mutational status, in comparison with their nontumorous counterparts. β-TRCP mRNA overexpression was associated with accumulation of intracytoplasmic and nuclear β-TrCP protein. In human liver tumor
cells without β-catenin mutations, Nkd-1 inhibited the Wnt-3a-activated Tcf-responsive-luciferase reporter activity, whereas Nkd-1 in hepatoblastomas
with β-catenin mutations had no antagonistic effect. Our data emphasize the inhibitory effect of β-TrCP and Nkd-1 on the Wnt signaling pathway
in a manner analogous to Conductin (AXIN2) and Dkk-1, inhibitors shown previously to be up-regulated in hepatoblastomas. Our
findings indicate that overexpression of the Wnt antagonists Nkd-1 and β-TrCP reveals an activation of the Wnt signaling pathway
as a common event in hepatoblastomas. We propose that Nkd-1 and β-TrCP may be used as possible diagnostic markers for the
activated Wnt signaling pathway in hepatoblastomas.
The interaction of influenza A viruses with the cell surface is controlled by the surface glycoproteins hemagglutinin (HA) and neuraminidase (NA). These two glycoproteins have opposing activities: HA ...is responsible for binding the host receptor (sialic acid) to allow infection, and NA is responsible for cleaving the receptor to facilitate virus release. Several studies have demonstrated that compatible levels of HA and NA activity are required for a virus to replicate efficiently. This is consequently of great interest for determining virus transmissibility. The concurrent role of these two proteins in receptor binding has never been directly measured. We demonstrate a novel biophysical approach based on bio-layer interferometry to measure the balance of the activities of these two proteins in real time. This technique measures virus binding to and release from a surface coated with either the human-like receptor analog α2,6-linked sialic acid or the avian-like receptor analog α2,3-linked sialic acid in both the presence and absence of NA inhibitors. Bio-layer interferometry measurements were also carried out to determine the effect of altering HA receptor affinity and NA stalk length on receptor binding.
Background: Influenza A viruses contain the surface glycoproteins hemagglutinin (HA) and neuraminidase (NA), responsible for receptor binding and virus release, respectively.
Results: The contribution of HA and NA to virus interactions with receptor-coated surfaces was measured using bio-layer interferometry.
Conclusion: The balance between the activities of the two glycoproteins controls virus-cell interactions, therefore transmissibility.
Significance: This technique can be used to examine factors underlying emergent virus transmissibility.
Over half of adults are seropositive for JC polyomavirus (JCV), but rare individuals develop progressive multifocal leukoencephalopathy (PML), a demyelinating JCV infection of the central nervous ...system. Previously, PML was primarily seen in immunosuppressed patients with AIDS or certain cancers, but it has recently emerged as a drug safety issue through its association with diverse immunomodulatory therapies. To better understand the relationship between the JCV life cycle and PML pathology, we studied autopsy brain tissue from a 70-year-old psoriasis patient on the integrin alpha-L inhibitor efalizumab following a ~2 month clinical course of PML. Sequence analysis of lesional brain tissue identified PML-associated viral mutations in regulatory (non-coding control region) DNA, capsid protein VP1, and the regulatory agnoprotein, as well as 9 novel mutations in capsid protein VP2, indicating rampant viral evolution. Nine samples, including three gross PML lesions and normal-appearing adjacent tissues, were characterized by histopathology and subject to quantitative genomic, proteomic, and molecular localization analyses. We observed a striking correlation between the spatial extent of demyelination, axonal destruction, and dispersion of JCV along white matter myelin sheath. Our observations in this case, as well as in a case of PML-like disease in an immunocompromised rhesus macaque, suggest that long-range spread of polyomavirus and axonal destruction in PML might involve extracellular association between virus and the white matter myelin sheath.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This article analyzes the effects of workplace social context on managers' and professionals' use of work-family policies in a financial services corporation. These official policies are ambiguous ...and contested and, as institutional theory implies, may fail to become fully implemented. We use a multilevel model to determine the individual-level and work group-level factors that affect respondents' policy use. In addition to individual-level factors, the social context of the workgroup affects employees' decisions to use work-family policies. We find support for our hypotheses stressing the social resource of power and protection: employees are more likely to use these policies if they work with powerful supervisors and colleagues, who can buffer them from perceived negative effects on their careers.
Steinernema feltiae is a moderately freezing tolerant nematode, that can withstand intracellular ice formation. We investigated recrystallization inhibition, thermal hysteresis and ice nucleation ...activities in the infective juveniles of S. feltiae. Both the splat cooling assay and optical recrystallometry indicate the presence of ice active substances that inhibit recrystallization in the nematode extract. The substance is relatively heat stable and largely retains the recrystallization inhibition activity after heating. No thermal hysteresis activity was detected but the extract had a typical hexagonal crystal shape when grown from a single seed crystal and weak ice nucleation activity. An ice active substance is present in a low concentration, which may be involved in the freezing survival of this species by inhibiting ice recrystallization.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Osteoarthritis (OA) is a common, debilitating, chronic disease with no disease-modifying drug approved to date. We discovered LNA043-a derivative of angiopoietin-like 3 (ANGPTL3)-as a potent ...chondrogenesis inducer using a phenotypic screen with human mesenchymal stem cells. We show that LNA043 promotes chondrogenesis and cartilage matrix synthesis in vitro and regenerates hyaline articular cartilage in preclinical OA and cartilage injury models in vivo. LNA043 exerts at least part of these effects through binding to the fibronectin receptor, integrin α
β
on mesenchymal stem cells and chondrocytes. In a first-in-human (phase 1), randomized, double-blinded, placebo-controlled, single ascending dose, single-center trial ( NCT02491281 ; sponsored by Novartis Pharmaceuticals), 28 patients with knee OA were injected intra-articularly with LNA043 or placebo (3:1 ratio) either 2 h, 7 d or 21 d before total knee replacement. LNA043 met its primary safety endpoint and showed short serum pharmacokinetics, cartilage penetration and a lack of immunogenicity (secondary endpoints). Post-hoc transcriptomics profiling of cartilage revealed that a single LNA043 injection reverses the OA transcriptome signature over at least 21 d, inducing the expression of hyaline cartilage matrix components and anabolic signaling pathways, while suppressing mediators of OA progression. LNA043 is a novel disease-modifying OA drug candidate that is currently in a phase 2b trial ( NCT04864392 ) in patients with knee OA.
Cerebral vasospasm (CV) and the resulting delayed cerebral ischemia (DCI) significantly contribute to poor outcomes following aneurysmal subarachnoid hemorrhage (aSAH). Free hemoglobin (Hb) within ...the subarachnoid space has been implicated in the pathogenesis of CV. Haptoglobin (Hp) binds free pro-oxidant Hb, thereby modulating its harmful effects. Humans can be of three Hp phenotypes: Hp1-1, Hp2-1, or Hp2-2. In several disease states, the Hp2-2 protein has been associated with reduced ability to protect against toxic free Hb. We hypothesized that individuals with the Hp2-2 phenotype would have more CV, DCI, mortality, and worse functional outcomes after aSAH. In a sample of 74 aSAH patients, Hp2-2 phenotype was significantly associated with increased focal moderate ( P = 0.014) and severe ( P = 0.008) CV and more global CV ( P = 0.014) after controlling for covariates. Strong trends toward increased mortality ( P = 0.079) and worse functional outcomes were seen for the Hp2-2 patients with modified Rankin scale at 6 wk ( P = 0.076) and at 1 y ( P = 0.051) and with Glasgow Outcome Scale Extended at discharge ( P = 0.091) and at 1 y ( P = 0.055). In conclusion, Hp2-2 phenotype is an independent risk factor for the development of both focal and global CV and also predicts poor functional outcomes and mortality after aSAH. Hp phenotyping may serve as a clinically useful tool in the critical care management of aSAH patients by allowing for early prediction of those patients who require increased vigilance due to their inherent genetic risk for the development of CV and resulting DCI and poor outcomes.
Significance Subarachnoid hemorrhage (SAH) is a devastating stroke subtype associated with an early age at onset and significant morbidity and mortality. Cerebral vasospasm (CV) is a common complication of SAH and a key contributor to poor outcomes due to the resulting brain ischemia and/or infarction. Blood bioproducts have been implicated in the development of CV, and haptoglobin (Hp), the hemoglobin-binding protein, may aid in attenuating this cascade of toxic effects. Here, we demonstrate that Hp phenotype is an independent risk factor for focal CV, and importantly, for global CV. We also show that Hp phenotype predicts mortality and poor outcomes. Although this work focuses on SAH, we expect that these findings will also apply to other acute neurological conditions.
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