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  • 11
    Online-Ressource
    Online-Ressource
    Wiley ; 2022
    In:  International Journal for Numerical Methods in Biomedical Engineering Vol. 38, No. 11 ( 2022-11)
    In: International Journal for Numerical Methods in Biomedical Engineering, Wiley, Vol. 38, No. 11 ( 2022-11)
    Kurzfassung: We report a computational study of mitochondria transport in a branched axon with two branches of different sizes. For comparison, we also investigate mitochondria transport in an axon with symmetric branches and in a straight (unbranched) axon. The interest in understanding mitochondria transport in branched axons is motivated by the large size of arbors of dopaminergic neurons, which die in Parkinson's disease. Since the failure of energy supply of multiple demand sites located in various axonal branches may be a possible reason for the death of these neurons, we were interested in investigating how branching affects mitochondria transport. Besides investigating mitochondria fluxes between the demand sites and mitochondria concentrations, we also studied how the mean age of mitochondria and mitochondria age densities depend on the distance from the soma. We established that if the axon splits into two branches of unequal length, the mean ages of mitochondria and age density distributions in the demand sites are affected by how the mitochondria flux splits at the branching junction (what portion of mitochondria enter the shorter branch and what portion enter the longer branch). However, if the axon splits into two branches of equal length, the mean ages and age densities of mitochondria are independent of how the mitochondria flux splits at the branching junction. This even holds for the case when all mitochondria enter one branch, which is equivalent to a straight axon. Because the mitochondrial membrane potential (which many researchers view as a proxy for mitochondrial health) decreases with mitochondria age, the independence of mitochondria age on whether the axon is symmetrically branched or straight (providing the two axons are of the same length), and on how the mitochondria flux splits at the branching junction, may explain how dopaminergic neurons can sustain very large arbors and still maintain mitochondrial health across branch extremities.
    Materialart: Online-Ressource
    ISSN: 2040-7939 , 2040-7947
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2022
    ZDB Id: 2540968-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 12
    Online-Ressource
    Online-Ressource
    Wiley ; 2021
    In:  International Journal for Numerical Methods in Biomedical Engineering Vol. 37, No. 12 ( 2021-12)
    In: International Journal for Numerical Methods in Biomedical Engineering, Wiley, Vol. 37, No. 12 ( 2021-12)
    Kurzfassung: Recent experimental observations have shown evidence of an unexpected sudden drop‐off in the dense core vesicles (DCVs) content at the ends of certain types of axon endings. This article seeks to determine whether these observations may be explained without modifying the parameters characterizing the ability of distal en passant boutons to capture and accumulate DCVs. We developed a mathematical model that is based on the conservation of captured and transiting DCVs in boutons. The model consists of 77 ordinary differential equations and is solved using a standard Matlab solver. We hypothesize that the drop in DCV content in distal boutons is due to an insufficient supply of anterogradely moving DCVs coming from the soma. As anterogradely moving DCVs are captured (and eventually destroyed) in more proximal boutons on their way to the end of the terminal, the fluxes of anterogradely moving DCVs between the boutons become increasingly smaller, and the most distal boutons are left without DCVs. We tested this hypothesis by modifying the flux of DCVs entering the terminal and found that the number of most distal boutons left unfilled increases if the DCV flux entering the terminal is decreased. The number of anterogradely moving DCVs in the axon can be increased either by the release of a portion of captured DCVs into the anterograde component or by an increase of the anterograde DCV flux into the terminal. This increase could lead to having enough anterogradely moving DCVs such that they could reach the most distal bouton and then turn around by changing molecular motors that propel them. The model suggests that this could result in an increased concentration of resident DCVs in distal boutons beginning with bouton 2 (the most distal is bouton 1). This is because in distal boutons, DCVs have a larger chance to be captured from the transiting state as they pass the boutons moving anterogradely and then again as they pass the same boutons moving retrogradely.
    Materialart: Online-Ressource
    ISSN: 2040-7939 , 2040-7947
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2021
    ZDB Id: 2540968-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 13
    Online-Ressource
    Online-Ressource
    Wiley ; 2023
    In:  International Journal for Numerical Methods in Biomedical Engineering
    In: International Journal for Numerical Methods in Biomedical Engineering, Wiley
    Kurzfassung: Recent publications report that although the mitochondria population in an axon can be quickly replaced by a combination of retrograde and anterograde axonal transport (often within less than 24 hours), the axon contains much older mitochondria. This suggests that not all mitochondria that reach the soma are degraded and that some are recirculating back into the axon. To explain this, we developed a model that simulates mitochondria distribution when a portion of mitochondria that return to the soma are redirected back to the axon rather than being destroyed in somatic lysosomes. Utilizing the developed model, we studied how the percentage of returning mitochondria affects the mean age and age density distributions of mitochondria at different distances from the soma. We also investigated whether turning off the mitochondrial anchoring switch can reduce the mean age of mitochondria. For this purpose, we studied the effect of reducing the value of a parameter that characterizes the probability of mitochondria transition to the stationary (anchored) state. The reduction in mitochondria mean age observed when the anchoring probability is reduced suggests that some injured neurons may be saved if the percentage of stationary mitochondria is decreased. The replacement of possibly damaged stationary mitochondria with newly synthesized ones may restore the energy supply in an injured axon. We also performed a sensitivity study of the mean age of stationary mitochondria to the parameter that determines what portion of mitochondria re‐enter the axon and the parameter that determines the probability of mitochondria transition to the stationary state. The sensitivity of the mean age of stationary mitochondria to the mitochondria stopping probability increases linearly with the number of compartments in the axon. High stopping probability in long axons can significantly increase mitochondrial age.
    Materialart: Online-Ressource
    ISSN: 2040-7939 , 2040-7947
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2023
    ZDB Id: 2540968-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 14
    Online-Ressource
    Online-Ressource
    Elsevier BV ; 2022
    In:  Journal of Theoretical Biology Vol. 546 ( 2022-08), p. 111161-
    In: Journal of Theoretical Biology, Elsevier BV, Vol. 546 ( 2022-08), p. 111161-
    Materialart: Online-Ressource
    ISSN: 0022-5193
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2022
    ZDB Id: 1470953-3
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 15
    Online-Ressource
    Online-Ressource
    Elsevier BV ; 2022
    In:  Mathematical Biosciences Vol. 344 ( 2022-02), p. 108754-
    In: Mathematical Biosciences, Elsevier BV, Vol. 344 ( 2022-02), p. 108754-
    Materialart: Online-Ressource
    ISSN: 0025-5564
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2022
    ZDB Id: 2010227-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 16
    In: Endocrine Connections, Bioscientifica, Vol. 6, No. 8 ( 2017-11), p. 557-565
    Kurzfassung: Primary hyperparathyroidism (PHPT) is a relatively rare disorder among children, adolescents and young adults. Its development at an early age is suspicious for hereditary causes, though the need for routine genetic testing remains controversial. Objective To identify and describe hereditary forms of PHPT in patients with manifestation of the disease under 40 years of age. Design We enrolled 65 patients with PHPT diagnosed before 40 years of age. Ten of them had MEN1 mutation, and PHPT in them was the first manifestation of multiple endocrine neoplasia type 1 syndrome. Methods The other fifty-five patients underwent next-generation sequencing (NGS) of a custom-designed panel of genes, associated with PHPT ( MEN1 , CASR , CDC73 , CDKN1A , CDKN1B , CDKN1C , CDKN2A , CDKN2C , CDKN2D ). In cases suspicious for gross CDC73 deletions multiplex ligation-dependent probe amplification was performed. Results NGS revealed six pathogenic or likely pathogenic germline sequence variants: four in CDC73 c.271C 〉 T (p.Arg91*), c.496C 〉 T (p.Gln166*), c.685A 〉 T (p.Arg229*) and c.787C 〉 T (p.Arg263Cys); one in CASR c.3145G 〉 T (p.Glu1049*) and one in MEN1 c.784-9G 〉 A. In two patients, MLPA confirmed gross CDC73 deletions. In total, 44 sporadic and 21 hereditary PHPT cases were identified. Parathyroid carcinomas and atypical parathyroid adenomas were present in 8/65 of young patients, in whom CDC73 mutations were found in 5/8. Conclusions Hereditary forms of PHPT can be identified in up to 1/3 of young patients with manifestation of the disease at 〈 40 years of age. Parathyroid carcinomas or atypical parathyroid adenomas in young patients are frequently associated with CDC73 mutations.
    Materialart: Online-Ressource
    ISSN: 2049-3614
    Sprache: Unbekannt
    Verlag: Bioscientifica
    Publikationsdatum: 2017
    ZDB Id: 2668428-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 17
    Online-Ressource
    Online-Ressource
    Elsevier BV ; 2020
    In:  Mathematical Biosciences Vol. 329 ( 2020-11), p. 108468-
    In: Mathematical Biosciences, Elsevier BV, Vol. 329 ( 2020-11), p. 108468-
    Materialart: Online-Ressource
    ISSN: 0025-5564
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2020
    ZDB Id: 2010227-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 18
    Online-Ressource
    Online-Ressource
    Informa UK Limited ; 2023
    In:  Computer Methods in Biomechanics and Biomedical Engineering
    In: Computer Methods in Biomechanics and Biomedical Engineering, Informa UK Limited
    Materialart: Online-Ressource
    ISSN: 1025-5842 , 1476-8259
    Sprache: Englisch
    Verlag: Informa UK Limited
    Publikationsdatum: 2023
    ZDB Id: 2049175-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 19
    Online-Ressource
    Online-Ressource
    Informa UK Limited ; 2023
    In:  Computer Methods in Biomechanics and Biomedical Engineering
    In: Computer Methods in Biomechanics and Biomedical Engineering, Informa UK Limited
    Materialart: Online-Ressource
    ISSN: 1025-5842 , 1476-8259
    Sprache: Englisch
    Verlag: Informa UK Limited
    Publikationsdatum: 2023
    ZDB Id: 2049175-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 20
    Online-Ressource
    Online-Ressource
    Informa UK Limited ; 2019
    In:  Computer Methods in Biomechanics and Biomedical Engineering Vol. 22, No. 1 ( 2019-01-02), p. 71-83
    In: Computer Methods in Biomechanics and Biomedical Engineering, Informa UK Limited, Vol. 22, No. 1 ( 2019-01-02), p. 71-83
    Materialart: Online-Ressource
    ISSN: 1025-5842 , 1476-8259
    Sprache: Englisch
    Verlag: Informa UK Limited
    Publikationsdatum: 2019
    ZDB Id: 2049175-X
    Standort Signatur Einschränkungen Verfügbarkeit
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