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https://www.readbyqxmd.com/read/27906631/mitochondrial-purine-and-pyrimidine-metabolism-and-beyond
#1
Liya Wang
Carefully balanced deoxynucleoside triphosphate (dNTP) pools are essential for both nuclear and mitochondrial genome replication and repair. Two synthetic pathways operate in cells to produce dNTPs, e.g., the de novo and the salvage pathways. The key regulatory enzymes for de novo synthesis are ribonucleotide reductase (RNR) and thymidylate synthase (TS), and this process is considered to be cytosolic. The salvage pathway operates both in the cytosol (TK1 and dCK) and the mitochondria (TK2 and dGK). Mitochondrial dNTP pools are separated from the cytosolic ones owing to the double membrane structure of the mitochondria, and are formed by the salvage enzymes TK2 and dGK together with NMPKs and NDPK in postmitotic tissues, while in proliferating cells the mitochondrial dNTPs are mainly imported from the cytosol produced by the cytosolic pathways...
December 2016: Nucleosides, Nucleotides & Nucleic Acids
https://www.readbyqxmd.com/read/27867407/twinkle-artefact-in-the-ultrasound-diagnosis-of-superficial-epidermoid-cysts
#2
Richard Clarke, Priya Suresh, Rose Thomas, Simon Freeman
AIM: The aim of the study was to evaluate whether the twinkle artefact is a valuable feature in the sonographic diagnosis of superficial epidermoid cysts. MATERIALS AND METHODS: A retrospective search was undertaken of our institution's Radiology Information System and pathology database to identify cases of superficial masses showing the twinkle artefact that proceeded to surgical excision. RESULTS: Eighteen superficial masses demonstrating the twinkle artefact were identified that were submitted for pathological analysis...
August 2016: Ultrasound: Journal of the British Medical Ultrasound Society
https://www.readbyqxmd.com/read/27846700/droplet-like-heterogeneity-of-aqueous-tetrahydrofuran-solutions-at-the-submicrometer-scale
#3
N F Bunkin, A V Shkirin, G A Lyakhov, A V Kobelev, N V Penkov, S V Ugraitskaya, E E Fesenko
A droplet formation in aqueous solutions of tetrahydrofuran (THF) has been experimentally detected at the submicrometer scale using two independent laser diagnostic techniques (dynamic light scattering and laser phase microscopy) and described in terms of THF-water intermolecular hydrogen bonding. It is shown that the nanodroplets have a mean size of 300 nm, their refractive index is higher than that of the ambient liquid, and they are highly enriched with THF molecules. The maximum of light scattering intensity falls within the THF concentration range 2-8 mol...
November 14, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/27814609/mitochondrial-nucleic-acid-binding-proteins-associated-with-diseases
#4
Takeshi Uchiumi, Dongchon Kang
Mammalian mitochondrial DNA (mtDNA) exists in structures called nucleoids, which correspond to the configuration of nuclear DNA. Mitochondrial transcription factor A (TFAM), first cloned as an mtDNA transcription factor, is critical for packaging and maintaining mtDNA. To investigate functional aspects of TFAM, we identified many RNA-binding proteins as candidate TFAM interactors, including ERAL1 and p32. In this review, we first describe the functions of TFAM, replication proteins such as polymerase gamma and Twinkle, and mitochondrial RNA binding proteins...
January 1, 2017: Frontiers in Bioscience (Landmark Edition)
https://www.readbyqxmd.com/read/27687733/dominant-factor-analysis-of-b-flow-twinkling-sign-with-phantom-and-simulation-data
#5
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
https://www.readbyqxmd.com/read/27551684/infantile-onset-spinocerebellar-ataxia-caused-by-compound-heterozygosity-for-twinkle-mutations-and-modeling-of-twinkle-mutations-causing-recessive-disease
#6
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
https://www.readbyqxmd.com/read/27444386/mitochondria-targeted-antioxidant-mitotempo-protects-mitochondrial-function-against-amyloid-beta-toxicity-in-primary-cultured-mouse-neurons
#7
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
https://www.readbyqxmd.com/read/27427710/imitating-musical-scores-on-a-chip-through-droplet-generation
#8
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
https://www.readbyqxmd.com/read/27364318/oxidative-dna-damage-stalls-the-human-mitochondrial-replisome
#9
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
https://www.readbyqxmd.com/read/27342873/twinkle-overexpression-prevents-cardiac-rupture-after-myocardial-infarction-by-alleviating-impaired-mitochondrial-biogenesis
#10
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
https://www.readbyqxmd.com/read/27226550/biochemical-characterization-of-the-human-mitochondrial-replicative-twinkle-helicase-substrate-specificity-dna-branch-migration-and-ability-to-overcome-blockades-to-dna-unwinding
#11
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
https://www.readbyqxmd.com/read/27170278/can-doppler-ultrasonography-twinkling-artifact-be-used-as-an-alternative-imaging-modality-to-non-contrast-enhanced-computed-tomography-in-patients-with-ureteral-stones-a-prospective-clinical-study
#12
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
https://www.readbyqxmd.com/read/27170168/clinical-scenarios-in-acute-kidney-injury-post-renal-acute-kidney-injury
#13
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
https://www.readbyqxmd.com/read/27126510/twinkling-artifact-on-color-doppler-ultrasound-an-advantage-or-a-pitfall
#14
REVIEW
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
https://www.readbyqxmd.com/read/27112570/mitochondrial-transcription-termination-factor-1-directs-polar-replication-fork-pausing
#15
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
https://www.readbyqxmd.com/read/27101752/natural-history-of-retinopathy-in-children-and-young-people-with-type-1-diabetes
#16
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
https://www.readbyqxmd.com/read/27076523/do-you-want-to-live-to-be-100-answers-from-older-people
#17
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
https://www.readbyqxmd.com/read/27065468/human-mitochondrial-dna-replication-machinery-and-disease
#18
REVIEW
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...
June 2016: Current Opinion in Genetics & Development
https://www.readbyqxmd.com/read/27063853/a-prospective-comparative-study-of-color-doppler-ultrasound-with-twinkling-and-noncontrast-computerized-tomography-for-the-evaluation-of-acute-renal-colic
#19
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
https://www.readbyqxmd.com/read/26979109/mitochondrial-dna-homeostasis-is-essential-for-nigrostriatal-integrity
#20
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
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