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1.
Nature ; 604(7905): 280-286, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35418631

RESUMO

Multijunction solar cells can overcome the fundamental efficiency limits of single-junction devices. The bandgap tunability of metal halide perovskite solar cells renders them attractive for multijunction architectures1. Combinations with silicon and copper indium gallium selenide (CIGS), as well as all-perovskite tandem cells, have been reported2-5. Meanwhile, narrow-gap non-fullerene acceptors have unlocked skyrocketing efficiencies for organic solar cells6,7. Organic and perovskite semiconductors are an attractive combination, sharing similar processing technologies. Currently, perovskite-organic tandems show subpar efficiencies and are limited by the low open-circuit voltage (Voc) of wide-gap perovskite cells8 and losses introduced by the interconnect between the subcells9,10. Here we demonstrate perovskite-organic tandem cells with an efficiency of 24.0 per cent (certified 23.1 per cent) and a high Voc of 2.15 volts. Optimized charge extraction layers afford perovskite subcells with an outstanding combination of high Voc and fill factor. The organic subcells provide a high external quantum efficiency in the near-infrared and, in contrast to paradigmatic concerns about limited photostability of non-fullerene cells11, show an outstanding operational stability if excitons are predominantly generated on the non-fullerene acceptor, which is the case in our tandems. The subcells are connected by an ultrathin (approximately 1.5 nanometres) metal-like indium oxide layer with unprecedented low optical/electrical losses. This work sets a milestone for perovskite-organic tandems, which outperform the best p-i-n perovskite single junctions12 and are on a par with perovskite-CIGS and all-perovskite multijunctions13.


Assuntos
Compostos de Cálcio , Índio , Cobre , Óxidos , Titânio
2.
Unfallchirurg ; 122(10): 791-798, 2019 Oct.
Artigo em Alemão | MEDLINE | ID: mdl-30478780

RESUMO

BACKGROUND AND OBJECTIVE: Posttraumatic or postoperative movement restrictions in elbow joints can often occur (including capsular contracture) and can generate everyday limitations. In persistent elbow stiffness, arthroscopic arthrolysis with removal of the dorsal and ventral capsule portions can be carried out. The purpose of this study was to assess the efficacy of arthroscopic capsulectomy by means of an in vitro anatomical study. METHODS: A standardized elbow arthroscopy with ventral and dorsal capsulectomy was performed and image-documented in five fresh-frozen elbow specimens. Subsequently, open dissection of the elbow joint was performed to analyze the amount of residual capsule by means of photodocumentation of the specimens. RESULTS: Regardless of the surgeon and surgical experience, anterior and posterior remnants of the capsule remained in all specimens. Dorsal capsule strands around the standard arthroscopy portals were noticed particularly more often in the area of the high dorsolateral camera portal. An incomplete capsulectomy was seen on the ulnar side at the level of the posterior medial ligament (PML) in the immediate vicinity of the ulnar nerve. Ventrally, a capsulectomy was performed from the radial side and also the ulnar side until the brachialis muscle and additionally a complete capsulectomy as far as the anterior medial ligament (AML) and radial collateral ligament (RCL) was achieved. The capsule was completely resected in a proximal direction. Distally, irrelevant capsular remnants were found in the region of the annular ligament and distal of the tip of the coronoid process. CONCLUSION: Arthroscopic arthrolysis can be performed with a high degree of radicality. The radicality must be self-critically taken into account in one's own action. The radicality of the portal change may even be higher ventrally than with an isolated column procedure. On the other hand, it must be critically considered that posteriorly, the PML cannot be adequately addressed by means of arthroscopy due to the risk of ulnar nerve injury. Portal changes might help to enable a more complete visualization of the joint capsule and may avoid leaving possibly relevant remnants of the capsule. If a release of the PML is required, this may have to be carried out in combination with an ulnar nerve release in a mini-open technique.


Assuntos
Artroscopia , Articulação do Cotovelo , Ligamentos , Músculo Esquelético , Nervo Ulnar
3.
Phys Rev Lett ; 119(13): 134801, 2017 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-29341696

RESUMO

In recent years the "crab-waist collision" scheme [P. Raimondi, Proceedings of 2nd SuperB Workshop, Frascati, 2006.; M. Zobov et al., Phys. Rev. Lett. 104, 174801 (2010)PRLTAO0031-900710.1103/PhysRevLett.104.174801] has become popular for circular e^{+} e^{-} colliders. The designs of several future colliders are based on this scheme. So far the beam-beam effects for collisions under a large crossing angle with or without crab waist were mostly studied using weak-strong simulations. We present here strong-strong simulations showing a novel strong coherent head-tail instability, which can limit the performance of proposed future colliders. We explain the underlying instability mechanism starting from the "cross-wake force" induced by the beam-beam interaction. Using this beam-beam wake, the beam-beam head tail modes are studied by an eigenmode analysis. The instability may affect all collider designs based on the crab-waist scheme. We suggest an experimental verification at SuperKEKB during its commissioning phase II.

4.
Neth Heart J ; 25(1): 40-46, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27785622

RESUMO

AIMS: Percutaneous coronary intervention (PCI) of bifurcation lesions can be performed using various techniques. The aim of this study was to analyse the outcome of various techniques of bifurcation stenting in all patients undergoing bifurcation stenting at one large intervention centre in 2013, taking into account that more complex lesions might more often warrant a two-stent technique. METHODS AND RESULTS: This retrospective study included 260 consecutive patients who underwent non-primary PCI of a bifurcation lesion at the Catharina Hospital, Eindhoven, in 2013. Patients were classified into two groups: one-stent technique (provisional stenting), and two-stent techniques (culotte, crush and T­stenting). The primary endpoint was the rate of restenosis at 1 year. The secondary endpoints were procedural complications (side branch occlusion, periprocedural infarction, and death) and major adverse cardiac events (MACE) at 1 year. Periprocedural complications occurred in 15 patients (5.8 %) with no difference between the groups (p = 0.27). After 1 year, restenosis occurred in 3.2 % of the patients in the one-stent technique group and 7.3 % in the two-stent technique group (p = 0.20). MACE at 1 year did not differ between the groups at 11.9 % and 12.2 % respectively (p = 1.00). CONCLUSIONS: This study shows that there is no significant difference between restenosis rate, or any other outcome parameter, with the different techniques of bifurcation stenting. Since provisional stenting is the simplest, most straightforward and cheapest approach, if technically feasible this technique has our preference as the initial approach, and an upgrade can be considered if the result is insufficient.

5.
Indoor Air ; 23(5): 406-16, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23464847

RESUMO

Radon plays an important role for human exposure to natural sources of ionizing radiation. The aim of this article is to compare two approaches to estimate mean radon exposure in the Swiss population: model-based predictions at individual level and measurement-based predictions based on measurements aggregated at municipality level. A nationwide model was used to predict radon levels in each household and for each individual based on the corresponding tectonic unit, building age, building type, soil texture, degree of urbanization, and floor. Measurement-based predictions were carried out within a health impact assessment on residential radon and lung cancer. Mean measured radon levels were corrected for the average floor distribution and weighted with population size of each municipality. Model-based predictions yielded a mean radon exposure of the Swiss population of 84.1 Bq/m(3) . Measurement-based predictions yielded an average exposure of 78 Bq/m(3) . This study demonstrates that the model- and the measurement-based predictions provided similar results. The advantage of the measurement-based approach is its simplicity, which is sufficient for assessing exposure distribution in a population. The model-based approach allows predicting radon levels at specific sites, which is needed in an epidemiological study, and the results do not depend on how the measurement sites have been selected.


Assuntos
Monitoramento Ambiental , Modelos Teóricos , Radônio/análise , Adolescente , Adulto , Fatores Etários , Idoso , Criança , Pré-Escolar , Habitação , Humanos , Lactente , Pessoa de Meia-Idade , Suíça , Adulto Jovem
6.
Strahlenther Onkol ; 188(5): 377-82, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22402868

RESUMO

BACKGROUND: Phase II trials of neoadjuvant treatment in UICC-TNM stage II and III rectal cancer with capecitabine and oxaliplatin demonstrated favourable rates on tumour regression with acceptable toxicity. PATIENTS AND METHODS: Retrospective evaluation of 34 patients treated from 2005-2008 outside clinical trials (CTR) with neoadjuvant irradiation (45-50.4 Gy) and simultaneous capecitabine 825 mg/m(2) b.i.d. on days 1-14 and 22-35 and oxaliplatin 50 mg/m(2) on days 1, 8, 22 and 29 (CAPOX). Twenty-six (77%) patients received one or two courses of capecitabine 1,000 mg/m(2) b.i.d. on days 1-14 and oxaliplatin 130 mg/m(2) on day 1 (XELOX) prior to simultaneous chemoradiotherapy. RESULTS: UICC-TNM stage regression was observed in 60% (n = 20). Dworak's regression grades 3 and 4 were achieved in 18.2% (n = 6) and 15.1% (n = 5) of the patients. Sphincter-preserving surgery was performed in 53% (n = 8) of patients with a tumour of the lower rectum. Within the mean observation of 24 months, none of the patients relapsed locally, 1 patient had progressive disease and 5 patients (15%) relapsed distantly. Toxicity of grade 3 and 4 was mainly diarrhoea 18% (n = 6) and perianal pain 9% (n = 3). Nevertheless, severe cardiac events (n = 2), severe electrolyte disturbances (n = 2), and syncopes (n = 2) were observed as well. CONCLUSION: Treatment efficacy and common toxicity are similar to the reports of phase I/II trials. However, several severe adverse events were observed in our cohort study. The predisposing factors for these events have yet to be studied and may have implications for the selection of patients outside CTR.


Assuntos
Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/radioterapia , Desoxicitidina/análogos & derivados , Fluoruracila/análogos & derivados , Compostos Organoplatínicos/uso terapêutico , Neoplasias Retais/tratamento farmacológico , Neoplasias Retais/radioterapia , Adenocarcinoma/patologia , Adenocarcinoma/cirurgia , Adulto , Idoso , Antineoplásicos/efeitos adversos , Antineoplásicos/uso terapêutico , Capecitabina , Terapia Combinada , Desoxicitidina/efeitos adversos , Desoxicitidina/uso terapêutico , Feminino , Fluoruracila/efeitos adversos , Fluoruracila/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Terapia Neoadjuvante , Compostos Organoplatínicos/efeitos adversos , Oxaliplatina , Neoplasias Retais/patologia , Neoplasias Retais/cirurgia , Estudos Retrospectivos , Resultado do Tratamento
7.
Phys Rev Lett ; 109(23): 234102, 2012 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-23368210

RESUMO

Time-varying nonlinear oscillatory systems produce phenomena of resonance crossing and trapping of particles in resonance islands. Traditionally, such processes have been analyzed in terms of adiabatic conditions. Considering, as an example, a simplified one-dimensional model describing the "electron-cloud pinch" during a bunch passage in a particle accelerator, here we present an approach to resonance trapping which does not require any adiabatic condition. Instead we introduce the concept of the attraction point and investigate invariance and scaling properties of motion close to the attraction point, considering a single resonance crossing.

8.
Curr Genomics ; 13(6): 426-32, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23450188

RESUMO

In radiotherapy the normal tissue reaction is often a limiting factor for radiation treatment. Still there is no screening method, which predicts normal tissue reaction on radiotherapy, especially in comparison to tumor tissue, and therefore allows tailoring of the radiation dose to each patient. Here, we present a case of severe radiation-related side effects. We applied classical cytogenetic techniques (Giemsa-banding and staining of centromeric regions), the comet assay as well as multicolor fluorescence in situ hybridization on peripheral blood lymphocytes of this patient in order to determine the radio-sensitivity on the DNA level and to correlate these findings with the clinical outcome. Our investigations revealed abnormalities on chromosome 9, deficiencies in the DNA-repair capacity after radiation exposure and a high number of radiation induced chromosomal aberrations. A detected high amount of residual damage two or three hours after radiation exposure and repair as well as the high number of chromosomal aberrations (ChAs) suggests a correlation between repair capacity and radiation induced ChAs. We concluded that the detected abnormalities might serve as a genetic basis for the radio-sensitive phenotype of this patient. Taken together this report strengthens the idea that intensive DNA genomic analysis of individual patients can serve as the basis for more favourable treatment of cancer patients.

9.
Ther Umsch ; 69(7): 420-8, 2012 Jul.
Artigo em Alemão | MEDLINE | ID: mdl-22753291

RESUMO

Radiotherapy is an important and well integrated part in modern treatment concepts for cancer of the lung and pleura. Thanks to technical progress in the last years radiotherapy has managed to prove its role in all stages of lung cancers and has opened a spectrum of new treatment options. Stereotactic radiotherapy of the early NSCLC has become the standard treatment for radically inoperable patients. It provides better local control rates than traditional conventionally fractionated radiotherapy. In stage III NSCLC, simultaneous radiochemotherapy is an effective option with equal results compared to surgery. The standard treatment for limited disease SCLC is primary simultaneous radiochemotherapy. All patients with good response after primary treatment profit from prophylactic cranial irradiation. Adjuvant radiotherapy is a component of the trimodal treatment for curative approaches in patients with pleura mesothelioma. Palliative radiotherapy is the standard treatment for brain metastases, bone metastases and compression or obstruction from thoracal tumour mass.


Assuntos
Quimiorradioterapia/tendências , Neoplasias Pulmonares/radioterapia , Cuidados Paliativos/tendências , Radioterapia Adjuvante/tendências , Radioterapia Conformacional/tendências , Humanos
10.
11.
Oper Orthop Traumatol ; 34(6): 419-430, 2022 Dec.
Artigo em Alemão | MEDLINE | ID: mdl-36074139

RESUMO

OBJECTIVE: Neutralizing a posteromedial rotatory instability (PMRI) caused by coronoid deficiency by restoration of the humeroulnar joint surface with an autologous iliac crest bone graft. INDICATIONS: Surgery is indicated in patients with chronic deficiency of the anteromedial facet of the coronoid with subsequent PMRI. CONTRAINDICATIONS: Coronoid reconstruction is not recommended in patients with advanced osteoarthritis of the elbow caused by subluxation of the humeroulnar joint. General contraindications like acute infection, pregnancy and lack of operability should also be taken into account. SURGICAL TECHNIQUE: First, a medial approach is established and the base of the coronoid is prepared. Afterwards an autologous iliac crest bone graft is placed onto the defect and secured by screws or a plate. In addition, a reconstruction of the anterior bundle of the medial collateral ligament with an autologous tendon graft is performed. POSTOPERATIVE MANAGEMENT: An elbow orthesis is worn for 6 weeks after surgery to avoid valgus or varus stress. There is no restriction in range of motion. A continuous passive motion elbow chair supports the patient in regaining elbow mobility. RESULTS: Between 2015 and 2017, we treated 10 patients suffering from chronic coronoid defects with coronoid reconstruction. Eight of the patients were available for follow-up 86 weeks after surgery. The mean age was 41.4 years. In all patients, elbow range of motion and patient-related outcome measures were improved after surgery. Plain radiographs illustrated correct centering of the elbow joint. One patient had to undergo elbow arthroplasty and was excluded. Coronoid reconstruction with an autologous iliac crest bone graft restored humeroulnar joint congruency and improved satisfaction in patients suffering from chronic coronoid deficiency.


Assuntos
Articulação do Cotovelo , Instabilidade Articular , Humanos , Adulto , Articulação do Cotovelo/diagnóstico por imagem , Articulação do Cotovelo/cirurgia , Ílio , Instabilidade Articular/cirurgia , Resultado do Tratamento
12.
Neth Heart J ; 24(4): 296-7, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26879944
13.
Neth Heart J ; 24(4): 300, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26879945
14.
Radiat Oncol ; 16(1): 81, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933118

RESUMO

INTRODUCTION: The current phase III EORTC 1420 Best-of trial (NCT02984410) compares the swallowing function after transoral surgery versus intensity modulated radiotherapy (RT) in patients with early-stage carcinoma of the oropharynx, supraglottis and hypopharynx. We report the analysis of the Benchmark Case (BC) procedures before patient recruitment with special attention to dysphagia/aspiration related structures (DARS). MATERIALS AND METHODS: Submitted RT volumes and plans from participating centers were analyzed and compared against the gold-standard expert delineations and dose distributions. Descriptive analysis of protocol deviations was conducted. Mean Sorensen-Dice similarity index (mDSI) and Hausdorff distance (mHD) were applied to evaluate the inter-observer variability (IOV). RESULTS: 65% (23/35) of the institutions needed more than one submission to achieve Quality assurance (RTQA) clearance. OAR volume delineations were the cause for rejection in 53% (40/76) of cases. IOV could be improved in 5 out of 12 OARs by more than 10 mm after resubmission (mHD). Despite this, final IOV for critical OARs in delineation remained significant among DARS by choosing an aleatory threshold of 0.7 (mDSI) and 15 mm (mHD). CONCLUSIONS: This is to our knowledge the largest BC analysis among Head and neck RTQA programs performed in the framework of a prospective trial. Benchmarking identified non-common OARs and target delineations errors as the main source of deviations and IOV could be reduced in a significant number of cases after this process. Due to the substantial resources involved with benchmarking, future benchmark analyses should assess fully the impact on patients' clinical outcome.


Assuntos
Benchmarking/métodos , Neoplasias Hipofaríngeas/radioterapia , Órgãos em Risco/efeitos da radiação , Neoplasias Orofaríngeas/radioterapia , Garantia da Qualidade dos Cuidados de Saúde/normas , Planejamento da Radioterapia Assistida por Computador/métodos , Supraglotite/radioterapia , Ensaios Clínicos Fase III como Assunto , Humanos , Neoplasias Hipofaríngeas/patologia , Variações Dependentes do Observador , Neoplasias Orofaríngeas/patologia , Prognóstico , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos , Supraglotite/patologia
16.
PLoS One ; 15(8): e0237244, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817663

RESUMO

BACKGROUND: Heart Rate Variability (HRV) represents efferent vagus nerve activity which is suggested to be inversely related to fundamental mechanisms of tumorigenesis and to be a predictor of prognosis in various types of cancer. HRV is also believed to predict the occurrence and severity of post-operative complications. We aimed to determine the role of pre-operative HRV as a prognostic factor in overall and cancer free survival in patients with colorectal cancer. METHODS: Retrospective analysis was performed in a detailed dataset of patients diagnosed with primary colorectal cancer between January 2010 and December 2016, who underwent curative surgical treatment. HRV was measured as time-domain parameters (SDNN (Standard Deviation of NN-intervals) and RMSSD (Root Mean Square of Successive Differences)) based on pre-operative 10 second ECGs. Groups were created by baseline HRV: Low HRV (SDNN <20ms or RMSSD <19ms) and normal HRV (SDNN ≥20ms or RMSSD ≥19ms). Primary endpoints were overall and cancer free survival. RESULTS: A total of 428 patients were included in this study. HRV was not significantly associated with overall survival (SDNN <20ms vs SDNN ≥20ms:24.4% vs 22.8%, adjusted HR = 0.952 (0.607-1.493), p = 0.829; RMSSD <19ms vs RMSSD ≥19ms:27.0% vs 19.5%, adjusted HR = 1.321 (0.802-2.178), p = 0.274) or cancer recurrence (SDNN <20ms vs ≥20ms:20.1% vs 18.7%, adjusted HR = 0.976 (0.599-1.592), p = 0.924; RMSSD <19ms vs ≥19ms, 21.5% vs 16.9%, adjusted HR = 1.192 (0.706-2.011), p = 0.511). There was no significant association between HRV and CEA-level at one year follow-up, or between HRV and occurrence of a post-operative complication or the severity of post-operative complications. CONCLUSIONS: Heart rate variability was not associated with overall or cancer free survival in patients with primary colorectal cancer who underwent curative surgical treatment. These results do not align with results found in studies including only patients with advanced cancer, which suggests that there is only an association in the other direction, cancer causing low HRV.


Assuntos
Neoplasias Colorretais/diagnóstico , Recidiva Local de Neoplasia/diagnóstico , Idoso , Feminino , Frequência Cardíaca , Humanos , Masculino , Período Pré-Operatório , Prognóstico , Análise de Sobrevida
18.
Allergy ; 64(4): 647-51, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19154550

RESUMO

BACKGROUND: The pollen-food syndrome (PFS) is an association of food allergies to fruits, nuts, and vegetables in patients with pollen allergy. Mal d 1, the major apple allergen, is one of the most commonly associated food allergens for birch pollen-allergic patients suffering from PFS. Although the reactions are due to cross-reactive IgE antibodies originally raised against pollen Bet v 1, not every Bet v 1-allergic patient develops clinical reactions towards apple. AIM OF THE STUDY: We speculate that distinct IgE epitopes are responsible for the clinical manifestation of PFS. To test this hypothesis we grafted five Mal d 1 stretches onto Bet v 1. The grafted regions were 7- or 8-amino acids long encompassing amino acids residues previously shown to be crucial for IgE recognition of Bet v 1. METHODS: A Bet v 1-Mal d 1 chimeric protein designated BMC was expressed in Escherichia coli and purified to homogeneity. IgE reactivity of BMC was tested with patients' sera originating from (i) Bet v 1-allergic patients displaying no clinical symptoms upon ingestion of apples; and (ii) Bet v 1-allergic patients displaying allergic symptoms upon ingestion of apples and other Bet v 1-related foods. RESULTS AND CONCLUSION: Compared to birch pollen-allergic individuals, patients suffering from PFS showed significantly higher IgE reactivity with BMC (chimeric protein). The results suggest that the Mal d 1 regions grafted onto the Bet v 1 sequence comprise important IgE epitopes recognized by Bet v 1-allergic patients suffering from allergy to apples.


Assuntos
Alérgenos/imunologia , Epitopos de Linfócito B/imunologia , Hipersensibilidade Alimentar/imunologia , Proteínas de Plantas/imunologia , Antígenos de Plantas , Betula/imunologia , Western Blotting , Reações Cruzadas , Ensaio de Imunoadsorção Enzimática , Humanos , Malus/efeitos adversos , Malus/imunologia , Pólen/imunologia , Reação em Cadeia da Polimerase , Proteínas Recombinantes/imunologia
19.
Science ; 270(5242): 1677-80, 1995 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-7502080

RESUMO

The arginine residue at position 586 of the GluR-B subunit renders heteromeric alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)-sensitive glutamate receptor channels impermeable to calcium. The codon for this arginine is introduced at the precursor messenger RNA (pre-mRNA) stage by site-selective adenosine editing of a glutamine codon. Heterozygous mice engineered by gene targeting to harbor an editing-incompetent GluR-B allele synthesized unedited GluR-B subunits and, in principal neurons and interneurons, expressed AMPA receptors with increased calcium permeability. These mice developed seizures and died by 3 weeks of age, showing that GluR-B pre-mRNA editing is essential for brain function.


Assuntos
Epilepsia/genética , Neurônios/metabolismo , Edição de RNA , Receptores de AMPA/genética , Alelos , Animais , Sequência de Bases , Cálcio/metabolismo , Epilepsia/patologia , Marcação de Genes , Ácido Glutâmico/metabolismo , Heterozigoto , Hipocampo/patologia , Hibridização In Situ , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Degeneração Neural , Reação em Cadeia da Polimerase , Células de Purkinje/metabolismo , Células Piramidais/metabolismo , Precursores de RNA/genética , Precursores de RNA/metabolismo , Receptores de AMPA/química , Receptores de AMPA/metabolismo
20.
Science ; 280(5369): 1610-3, 1998 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-9616125

RESUMO

Glial cells produce myelin and contribute to axonal morphology in the nervous system. Two myelin membrane proteolipids, PLP and DM20, were shown to be essential for the integrity of myelinated axons. In the absence of PLP-DM20, mice assembled compact myelin sheaths but subsequently developed widespread axonal swellings and degeneration, associated predominantly with small-caliber nerve fibers. Similar swellings were absent in dysmyelinated shiverer mice, which lack myelin basic protein (MBP), but recurred in MBP*PLP double mutants. Thus, fiber degeneration, which was probably secondary to impaired axonal transport, could indicate that myelinated axons require local oligodendroglial support.


Assuntos
Axônios/fisiologia , Axônios/ultraestrutura , Sistema Nervoso Central/ultraestrutura , Proteína Proteolipídica de Mielina/fisiologia , Degeneração Neural/patologia , Proteínas do Tecido Nervoso , Animais , Transporte Axonal , Comunicação Celular , Feminino , Camundongos , Camundongos Mutantes Neurológicos , Modelos Neurológicos , Atividade Motora , Proteína Proteolipídica de Mielina/análise , Proteína Proteolipídica de Mielina/genética , Bainha de Mielina/química , Bainha de Mielina/fisiologia , Bainha de Mielina/ultraestrutura , Oligodendroglia/fisiologia , Nervo Óptico/ultraestrutura , Organelas/ultraestrutura , Medula Espinal/ultraestrutura , Transgenes
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