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Weijia Lu, Bruno Haider
BACKGROUND AND PURPOSE: The twinkling sign in B-flow imaging (BFI-TS) has been reported in the literature to increase both specificity and sensitivity compared to the traditional gray-scale imaging. Unfortunately, there has been no conclusive study on the mechanism of this effect. METHODS: In the study presented here, a comparative test on phantoms is introduced, where the variance of a phase estimator is used to quantify the motion amplitude. The statistical inference is employed later to find the dominate factor for the twinkling sign, which is proven by computer simulation...
September 29, 2016: Journal of Medical Ultrasonics
Sarah B Pierce, Suleyman Gulsuner, Gail A Stapleton, Tom Walsh, Ming K Lee, Jessica B Mandell, Augusto Morales, Rachel E Klevit, Mary-Claire King, R Curtis Rogers
Mutations in nuclear genes required for the replication and maintenance of mitochondrial DNA cause progressive multisystemic neuromuscular disorders with overlapping phenotypes. Biallelic mutations in C10orf2, encoding the Twinkle mitochondrial DNA helicase, lead to infantile-onset cerebellar ataxia (IOSCA), as well as milder and more severe phenotypes. We present a 13-year-old girl with ataxia, severe hearing loss, optic atrophy, peripheral neuropathy, and hypergonadotropic hypogonadism. Whole-exome sequencing revealed that the patient is compound heterozygous for previously unreported variants in the C10orf2 gene: a paternally inherited frameshift variant (c...
July 2016: Cold Spring Harbor Molecular Case Studies
Hongtao Hu, Mo Li
Mitochondrial defects including excess reactive oxygen species (ROS) production and compromised ATP generation are featured pathology in Alzheimer's disease (AD). Amyloid beta (Aβ)-mediated mitochondrial ROS overproduction disrupts intra-neuronal Redox balance, in turn exacerbating mitochondrial dysfunction leading to neuronal injury. Previous studies have found the beneficial effects of mitochondria-targeted antioxidants in preventing mitochondrial dysfunction and neuronal injury in AD animal and cell models, suggesting that mitochondrial ROS scavengers hold promise for the treatment of this neurological disorder...
September 9, 2016: Biochemical and Biophysical Research Communications
Xiaoyun Shawn Yang, Soojeong Shin, Woon Seob Lee, Jong Wook Hong
We have demonstrated fine control of droplet volumes on a chip using pneumatically actuated micro valve systems resulting in confined nanoliter or picoliter reagent generation. Using the micro valves, we are able to align multi-inlet droplet generating chips for systematic generation of combinatorial mixtures of chemical constituents. By following the change of chemical conditions such as pH we converted musical note information into sequential droplets representing musical scores of 'Twinkle little star.' It would just one of the interesting application of micro-droplet generation systems based on accurate droplet generation, mixing, and incubation...
June 2016: Journal of Nanoscience and Nanotechnology
Gorazd Stojkovič, Alena V Makarova, Paulina H Wanrooij, Josefin Forslund, Peter M Burgers, Sjoerd Wanrooij
Oxidative stress is capable of causing damage to various cellular constituents, including DNA. There is however limited knowledge on how oxidative stress influences mitochondrial DNA and its replication. Here, we have used purified mtDNA replication proteins, i.e. DNA polymerase γ holoenzyme, the mitochondrial single-stranded DNA binding protein mtSSB, the replicative helicase Twinkle and the proposed mitochondrial translesion synthesis polymerase PrimPol to study lesion bypass synthesis on oxidative damage-containing DNA templates...
2016: Scientific Reports
Takahiro Inoue, Masataka Ikeda, Tomomi Ide, Takeo Fujino, Yuka Matsuo, Shinobu Arai, Keita Saku, Kenji Sunagawa
Cardiac rupture is a fatal complication after myocardial infarction (MI). However, the detailed mechanism underlying cardiac rupture after MI remains to be fully elucidated. In this study, we investigated the role of mitochondrial DNA (mtDNA) and mitochondria in the pathophysiology of cardiac rupture by analyzing Twinkle helicase overexpression mice (TW mice). Twinkle overexpression increased mtDNA copy number approximately twofold and ameliorated ischemic cardiomyopathy at day 28 after MI. Notably, Twinkle overexpression markedly prevented cardiac rupture and improved post-MI survival, accompanied by the suppression of MMP-2 and MMP-9 in the MI border area at day 5 after MI when cardiac rupture frequently occurs...
September 1, 2016: American Journal of Physiology. Heart and Circulatory Physiology
Irfan Khan, Jack D Crouch, Sanjay Kumar Bharti, Joshua A Sommers, Sean M Carney, Elena Yakubovskaya, Miguel Garcia-Diaz, Michael A Trakselis, Robert M Brosh
Mutations in the c10orf2 gene encoding the human mitochondrial DNA replicative helicase Twinkle are linked to several rare genetic diseases characterized by mitochondrial defects. In this study, we have examined the catalytic activity of Twinkle helicase on model replication fork and DNA repair structures. Although Twinkle behaves as a traditional 5' to 3' helicase on conventional forked duplex substrates, the enzyme efficiently dissociates D-loop DNA substrates irrespective of whether it possesses a 5' or 3' single-stranded tailed invading strand...
July 1, 2016: Journal of Biological Chemistry
Volkan Sen, Cetin Imamoglu, Ibrahim Kucukturkmen, Tansu Degirmenci, Ibrahim Halil Bozkurt, Tarik Yonguc, Ozgu Aydogdu, Bulent Gunlusoy
We aimed to evaluate the use of twinkling artifact (TA) on color Doppler ultrasonography (USG) as an alternative imaging modality to non-contrast-enhanced computed tomography (CT) in patients with ureteral stones in this prospective study. Totally, 106 consecutive patients who had been diagnosed with ureterolithiasis by CT were enrolled in this prospective study. A urinary system color Doppler ultrasonography was performed on the same day with CT by an experienced radiologist who was blinded to the CT scan...
May 12, 2016: Urolithiasis
Mario Meola, Sara Samoni, Ilaria Petrucci, Claudio Ronco
The incidence of acute kidney injury related to urinary tract obstruction is low (1-10%). It occurs in bilateral renal or lower urinary tract obstruction or in ureter obstruction in patients with a single functioning kidney or with pre-existing chronic kidney disease. The etiology and the incidence of obstruction vary on the basis of age and gender. Conventional ultrasound has a high sensitivity (>95%), but low specificity (<70%) in the diagnosis of urinary tract obstruction. Nevertheless, color Doppler is used through the evaluation of renal resistive indexes, ureteral jet and twinkling artifact...
2016: Contributions to Nephrology
Ebru Ozan, Gokce Kaan Atac, Sadi Gundogdu
The twinkling artifact (TA) or color comet-tail artifact is characterized by a rapidly changing mixture of red and blue color Doppler signals. Even though many diseases and clinical conditions have been shown to produce this artifact, its source is not clearly understood yet. The TA may provide additional information to gray-scale ultrasound findings in several clinical situations. However, there may be pitfalls to keep in mind. We must first be aware of the TA to benefit from the advantages and avoid the pitfalls...
July 2016: Journal of Medical Ultrasonics
Yonghong Shi, Viktor Posse, Xuefeng Zhu, Anne K Hyvärinen, Howard T Jacobs, Maria Falkenberg, Claes M Gustafsson
During replication of nuclear ribosomal DNA (rDNA), clashes with the transcription apparatus can cause replication fork collapse and genomic instability. To avoid this problem, a replication fork barrier protein is situated downstream of rDNA, there preventing replication in the direction opposite rDNA transcription. A potential candidate for a similar function in mitochondria is the mitochondrial transcription termination factor 1 (MTERF1, also denoted mTERF), which binds to a sequence just downstream of the ribosomal transcription unit...
July 8, 2016: Nucleic Acids Research
N Dhillon, A Karthikeyan, A Castle, P Dodson, W Högler, J Kirk, N Krone, J Nolan, T Barrett
PurposeTo describe the prevalence and natural history of retinopathy in a cohort of children and young people with type 1 diabetes attending a tertiary hospital diabetes clinic.MethodsWe analysed retinopathy screening data from 2008 to 2010 on all eligible children using the 'Twinkle' diabetes database and the regional retinal screening database.ResultsA total of 88% (149/169) of eligible children were screened in 2008, median age 14 years, 52% male. The prevalence of retinopathy was 19.5% (30/149). All children had background retinopathy grade R1...
July 2016: Eye
Helena Karppinen, Marja-Liisa Laakkonen, Timo E Strandberg, Emmi A Huohvanainen, Kaisu H Pitkala
BACKGROUND: little is known about the oldest-olds' views on ageing. OBJECTIVE: to investigate older people's desire and the reasons they give for wanting to live to 100. DESIGN: a postal questionnaire, analysed both quantitatively and qualitatively. SETTING: population based in Helsinki, Finland. SUBJECTS: a random sample (response rate 64%; N = 1,405) of community-dwelling older people (aged 75-96)...
July 2016: Age and Ageing
Matthew J Young, William C Copeland
The human mitochondrial genome is replicated by DNA polymerase γ in concert with key components of the mitochondrial DNA (mtDNA) replication machinery. Defects in mtDNA replication or nucleotide metabolism cause deletions, point mutations, or depletion of mtDNA. The resulting loss of cellular respiration ultimately induces mitochondrial genetic diseases, including mtDNA depletion syndromes (MDS) such as Alpers or early infantile hepatocerebral syndromes, and mtDNA deletion disorders such as progressive external ophthalmoplegia, ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy...
April 8, 2016: Current Opinion in Genetics & Development
Mahmoud Abdel-Gawad, Ravi D Kadasne, Emad Elsobky, Bedeir Ali-El-Dein, Manoj Monga
PURPOSE: We performed a prospective comparison of the use of twinkling color Doppler ultrasound and noncontrast computerized tomography in the diagnosis of renal colic in emergency room patients. MATERIALS AND METHODS: A total of 815 consecutive adult patients with suspected renal colic presented to the emergency room and were evaluated immediately with color Doppler ultrasound and noncontrast computerized tomography. The site, side and maximum transverse diameter of the stones were assessed...
September 2016: Journal of Urology
Charalampos Tzoulis, Thomas Schwarzlmüller, Martin Biermann, Kristoffer Haugarvoll, Laurence A Bindoff
Mitochondrial involvement in the pathogenesis of Parkinson's disease has been suggested by multiple studies, but the mechanisms involved remain unresolved. Here, we sought to identify which mitochondrial defects are associated with degeneration of the nigrostriatal system. Nigrostriatal integrity was assessed in vivo by dopamine transporter (DAT) imaging in twenty-one patients with mitochondrial disorders of different molecular aetiology including: maternally inherited mitochondrial DNA (mtDNA) point mutations, primary single mtDNA deletions, nuclear-encoded disorders of mtDNA replication and maintenance due to mutations in POLG or C10orf2 (Twinkle), and mutations in other nuclear mitochondrial genes including the mitochondrial aspartyl-tRNA synthetase (DARS2) and ADCK3 genes...
May 2016: Mitochondrion
Leigh A M Demain, Jill E Urquhart, James O'Sullivan, Simon G Williams, Sanjeev S Bhaskar, Emma M Jenkinson, Charles M Lourenco, Arvid Heiberg, Simon H Pearce, Stavit A Shalev, Wyatt W Yue, Sabrina Mackinnon, Kevin J Munro, Ruth Newbury-Ecob, Kristen Becker, Min Jeong Kim, Raymond T O' Keefe, William G Newman
Perrault syndrome is a rare autosomal recessive disorder characterised by sensorineural hearing loss (SNHL) in both sexes and primary ovarian insufficiency in 46, XX karyotype females. Biallelic variants in five genes are reported to be causative: HSD17B4, HARS2, LARS2, CLPP and C10orf2. Here we present eight families affected by Perrault syndrome. In five families we identified novel or previously reported variants in HSD17B4, LARS2, CLPP and C10orf2. The proband from each family was whole exome sequenced and variants confirmed by Sanger sequencing...
March 11, 2016: Clinical Genetics
Joni Nikkanen, Saara Forsström, Liliya Euro, Ilse Paetau, Rebecca A Kohnz, Liya Wang, Dmitri Chilov, Jenni Viinamäki, Anne Roivainen, Päivi Marjamäki, Heidi Liljenbäck, Sofia Ahola, Jana Buzkova, Mügen Terzioglu, Nahid A Khan, Sini Pirnes-Karhu, Anders Paetau, Tuula Lönnqvist, Antti Sajantila, Pirjo Isohanni, Henna Tyynismaa, Daniel K Nomura, Brendan J Battersby, Vidya Velagapudi, Christopher J Carroll, Anu Suomalainen
Mitochondrial dysfunction affects cellular energy metabolism, but less is known about the consequences for cytoplasmic biosynthetic reactions. We report that mtDNA replication disorders caused by TWINKLE mutations-mitochondrial myopathy (MM) and infantile onset spinocerebellar ataxia (IOSCA)-remodel cellular dNTP pools in mice. MM muscle shows tissue-specific induction of the mitochondrial folate cycle, purine metabolism, and imbalanced and increased dNTP pools, consistent with progressive mtDNA mutagenesis...
April 12, 2016: Cell Metabolism
Sylvie Bannwarth, Laetitia Berg-Alonso, Gaëlle Augé, Konstantina Fragaki, Jill E Kolesar, Françoise Lespinasse, Sandra Lacas-Gervais, Fanny Burel-Vandenbos, Elodie Villa, Frances Belmonte, Jean-François Michiels, Jean-Ehrland Ricci, Romain Gherardi, Lea Harrington, Brett A Kaufman, Véronique Paquis-Flucklinger
Mutations in genes coding for mitochondrial helicases such as TWINKLE and DNA2 are involved in mitochondrial myopathies with mtDNA instability in both human and mouse. We show that inactivation of Pif1, a third member of the mitochondrial helicase family, causes a similar phenotype in mouse. pif1-/- animals develop a mitochondrial myopathy with respiratory chain deficiency. Pif1 inactivation is responsible for a deficiency to repair oxidative stress-induced mtDNA damage in mouse embryonic fibroblasts that is improved by complementation with mitochondrial isoform mPif1(67)...
September 2016: Mitochondrion
Juliette Bouchereau, Sandrine Vuillaumier Barrot, Thierry Dupré, Stuart E H Moore, Ruxandra Cardas, Yline Capri, Pauline Gaignard, Abdelhamid Slama, Catherine Delanoë, Hélène Ogier de Baulny, Nathalie Seta, Manuel Schiff, Laurent Servais
The C10orf2 gene encodes Twinkle, a protein involved in mitochondrial DNA (mtDNA) replication. Twinkle mutations cause mtDNA deletion or depletion and are associated with a large spectrum of clinical symptoms including dominant progressive external ophthalmoplegia (adPEO), infantile-onset spinocerebellar ataxia (IOSCA), and early-onset encephalopathy. The diagnosis remains difficult because of the wide range of symptoms and lack of association with specific metabolic changes. We report herein a child with early-onset encephalopathy, unusual abnormal movements, deafness, and axonal neuropathy...
February 27, 2016: JIMD Reports
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