Co-localisation of intra-nuclear membrane type-1 matrix metalloproteinase and hypoxia inducible factor-2α in osteosarcoma and prostate carcinoma cells.

Increased membrane type-1 matrix metalloproteinase (MT1-MMP) expression in osteosarcoma is predictive of poor prognosis and directs bone metastasis in prostate carcinoma. MT1-MMP subcellular localisation varies with oxygen tension, and, therefore, the aim of the present study was to assess protein interactions between MT1-MMP and the hypoxia inducible factors (HIF-1α and HIF-2α). MT1-MMP protein expression was investigated across a panel of cancer cell lines, including a positive and negative control. The hypoxia-induced alteration in subcellular location of MT1-MMP, HIF-1α and HIF-2α in the U2OS osteosarcoma cell line was assessed using subcellular fractionation. A proximity ligation assay was utilised to assess protein to protein interactions in the osteosarcoma U2OS and prostate carcinoma PC3 cell lines. U2OS and PC3 cells exhibited a significantly increased intra-nuclear interaction between MT1-MMP and HIF-2α in response to hypoxia. The role of this warrants further investigation as it may unveil novel opportunities to target MT1-MMP, which is of particular significance for osteosarcoma since current treatment options are limited.

Nasal Airway Obstruction Study (NAIROS): a phase III, open-label, mixed-methods, multicentre randomised controlled trial of septoplasty versus medical management of a septal deviation with nasal obstruction.

BACKGROUND: Septoplasty (surgery to straighten a deviation in the nasal septum) is a frequently performed operation worldwide, with approximately 250,000 performed annually in the US and 22,000 in the UK. Most septoplasties aim to improve diurnal and nocturnal nasal obstruction. The evidence base for septoplasty clinical effectiveness is hitherto very limited. AIMS: To establish, and inform guidance for, the best management strategy for individuals with nasal obstruction associated with a deviated septum. METHODS/DESIGN: A multicentre, mixed-methods, open label, randomised controlled trial of septoplasty versus medical management for adults with a deviated septum and a reduced nasal airway. Eligible patients will have septal deflection visible at nasendoscopy and a nasal symptom score ≥ 30 on the NOSE questionnaire. Surgical treatment comprises septoplasty with or without reduction of the inferior nasal turbinate on the anatomically wider side of the nose. Medical management comprises a nasal saline spray followed by a fluorinated steroid spray daily for six months. The recruitment target is 378 patients, recruited from up to 17 sites across Scotland, England and Wales. Randomisation will be on a 1:1 basis, stratified by gender and severity (NOSE score). Participants will be followed up for 12 months post randomisation. The primary outcome measure is the total SNOT-22 score at 6 months. Clinical and economic outcomes will be modelled against baseline severity (NOSE scale) to inform clinical decision-making. The study includes a recruitment enhancement process, and an economic evaluation. DISCUSSION: The NAIROS trial will evaluate the clinical effectiveness and cost-effectiveness of septoplasty versus medical management for adults with a deviated septum and symptoms of nasal blockage. Identifying those individuals most likely to benefit from surgery should enable more efficient and effective clinical decision-making, and avoid unnecessary operations where there is low likelihood of patient benefit. TRIAL REGISTRATION: EudraCT: 2017-000893-12, ISRCTN: 16168569. Registered on 24 March 2017.

Hyperpolarization-activated current (I(h)) in vestibular calyx terminals: characterization and role in shaping postsynaptic events.

Calyx afferent terminals engulf the basolateral region of type I vestibular hair cells, and synaptic transmission across the vestibular type I hair cell/calyx is not well understood. Calyces express several ionic conductances, which may shape postsynaptic potentials. These include previously described tetrodotoxin-sensitive inward Na(+) currents, voltage-dependent outward K(+) currents and a K(Ca) current. Here, we characterize an inwardly rectifying conductance in gerbil semicircular canal calyx terminals (postnatal days 3-45), sensitive to voltage and to cyclic nucleotides. Using whole-cell patch clamp, we recorded from isolated calyx terminals still attached to their type I hair cells. A slowly activating, noninactivating current (I(h)) was seen with hyperpolarizing voltage steps negative to the resting potential. External Cs(+) (1-5 mM) and ZD7288 (100 µM) blocked the inward current by 97 and 83 %, respectively, confirming that I(h) was carried by hyperpolarization-activated, cyclic nucleotide gated channels. Mean half-activation voltage of I(h) was -123 mV, which shifted to -114 mV in the presence of cAMP. Activation of I(h) was well described with a third order exponential fit to the current (mean time constant of activation, τ, was 190 ms at -139 mV). Activation speeded up significantly (τ=136 and 127 ms, respectively) when intracellular cAMP and cGMP were present, suggesting that in vivo I(h) could be subject to efferent modulation via cyclic nucleotide-dependent mechanisms. In current clamp, hyperpolarizing current steps produced a time-dependent depolarizing sag followed by either a rebound afterdepolarization or an action potential. Spontaneous excitatory postsynaptic potentials (EPSPs) became larger and wider when I(h) was blocked with ZD7288. In a three-dimensional mathematical model of the calyx terminal based on Hodgkin-Huxley type ionic conductances, removal of I(h) similarly increased the EPSP, whereas cAMP slightly decreased simulated EPSP size and width.

Sporadic intragenic inversion of the mitochondrial DNA MTND1 gene causing fatal infantile lactic acidosis.

Mutations of mitochondrial DNA (mtDNA) are an important cause of genetic disease, yet rarely present in the neonatal period. Here we report the clinical, biochemical, and molecular genetic findings of an infant who died at the age of 1 mo with marked biventricular hypertrophy, aortic coarctation, and severe lactic acidosis due to a previously described but unusual mtDNA mutation, a 7-bp intragenic inversion within the mitochondrial gene encoding ND1 protein of complex I (MTND1). In direct contrast to the previous case, an adult with exercise intolerance who only harbored the mutation in muscle, the MTND1 inversion in our patient was present at high levels in several tissues including the heart, muscle, liver, and cultured skin fibroblasts. There was no evidence of the mutation or respiratory complex I defect in a muscle biopsy from the patient's mother. Transmitochondrial cytoplasmic hybrids (cybrids) containing high mutant loads of the inversion expressed the biochemical defect but apparently normal levels of the assembled complex. Our report highlights the enormous phenotypic diversity that exists among pathogenic mtDNA mutations and reemphasizes the need for appropriate genetic counseling for families affected by mtDNA disease.