Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 125
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sci Rep ; 10(1): 7593, 2020 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-32371885

RESUMO

In light of the limited treatment options of diabetic polyneuropathy (DPN) available, suitable animal models are essential to investigate pathophysiological mechanisms and to identify potential therapeutic targets. In vivo evaluation with current techniques, however, often provides only restricted information about disease evolution. In the study of patients with DPN, magnetic resonance neurography (MRN) has been introduced as an innovative diagnostic tool detecting characteristic lesions within peripheral nerves. We developed a novel multicontrast ultra high field MRN strategy to examine major peripheral nerve segments in diabetic mice non-invasively. It was first validated in a cross-platform approach on human nerve tissue and then applied to the popular streptozotocin(STZ)-induced mouse model of DPN. In the absence of gross morphologic alterations, a distinct MR-signature within the sciatic nerve was observed mirroring subtle changes of the nerves' fibre composition and ultrastructure, potentially indicating early re-arrangements of DPN. Interestingly, these signal alterations differed from previously reported typical nerve lesions of patients with DPN. The capacity of our approach to non-invasively assess sciatic nerve tissue structure and function within a given mouse model provides a powerful tool for direct translational comparison to human disease hallmarks not only in diabetes but also in other peripheral neuropathic conditions.

3.
J Exp Biol ; 223(Pt 5)2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-31988164

RESUMO

Most non-mammal tetrapods have a hinge-like jaw operation restricted to vertical opening and closing movements. Many mammal jaw joints, by contrast, operate in more complex, three-dimensional (3D) ways, involving not only vertical but also propalinal (rostro-caudal) and transverse (lateral) movements. Data on intraoral food processing in lissamphibians and sauropsids has prompted a generally accepted view that these groups mostly swallow food unreduced, and that in those cases where lissamphibians and sauropsids chew, they mostly use simple vertical jaw movements for food processing. The exception to this generally accepted view is the occurrence of some propalinal chewing in sauropsids. We combined 3D kinematics and morphological analyses from biplanar high-speed video fluoroscopy and micro-computed tomography to determine how the paedomorphic salamander Siren intermedia treats captured food. We discovered not only that S. intermedia uses intraoral food processing but also that the elaborated morphology of its jaw joint facilitates mandibular motions in all three planes, resulting in complex 3D chewing. Thus, our data challenge the commonly held view that complex 3D chewing movements are exclusive to mammals, by suggesting that such mechanisms might have evolved early in the tetrapod evolution.

4.
Acta Neuropathol ; 139(1): 193-209, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31563982

RESUMO

The "isomorphic subtype of diffuse astrocytoma" was identified histologically in 2004 as a supratentorial, highly differentiated glioma with low cellularity, low proliferation and focal diffuse brain infiltration. Patients typically had seizures since childhood and all were operated on as adults. To define the position of these lesions among brain tumours, we histologically, molecularly and clinically analysed 26 histologically prototypical isomorphic diffuse gliomas. Immunohistochemically, they were GFAP-positive, MAP2-, OLIG2- and CD34-negative, nuclear ATRX-expression was retained and proliferation was low. All 24 cases sequenced were IDH-wildtype. In cluster analyses of DNA methylation data, isomorphic diffuse gliomas formed a group clearly distinct from other glial/glio-neuronal brain tumours and normal hemispheric tissue, most closely related to paediatric MYB/MYBL1-altered diffuse astrocytomas and angiocentric gliomas. Half of the isomorphic diffuse gliomas had copy number alterations of MYBL1 or MYB (13/25, 52%). Gene fusions of MYBL1 or MYB with various gene partners were identified in 11/22 (50%) and were associated with an increased RNA-expression of the respective MYB-family gene. Integrating copy number alterations and available RNA sequencing data, 20/26 (77%) of isomorphic diffuse gliomas demonstrated MYBL1 (54%) or MYB (23%) alterations. Clinically, 89% of patients were seizure-free after surgery and all had a good outcome. In summary, we here define a distinct benign tumour class belonging to the family of MYB/MYBL1-altered gliomas. Isomorphic diffuse glioma occurs both in children and adults, has a concise morphology, frequent MYBL1 and MYB alterations and a specific DNA methylation profile. As an exclusively histological diagnosis may be very challenging and as paediatric MYB/MYBL1-altered diffuse astrocytomas may have the same gene fusions, we consider DNA methylation profiling very helpful for their identification.

5.
Methods Mol Biol ; 2050: 113-120, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31468485

RESUMO

Targeted electroporation by using glass microelectrodes is a popular and versatile tool allowing for easy manipulation of single cells and cell ensembles in living tissue. Because of the highly focal distribution of the electric field, however, the range of reversible electroporation without causing irreversible damage is tight-especially when aiming for larger electroporation volumes. In this chapter, we describe the production of nanoengineered electroporation microelectrodes (NEMs), a practicable way to prepare glass microelectrodes providing a more even distribution around the tip of a pipette by using nanotechnological methods.

7.
Prev Vet Med ; 172: 104803, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31634754

RESUMO

The objective of this study was to investigate the new differential somatic cell count (DSCC) as a supplementary indicator to SCC for the identification of intramammary infection (IMI) in dairy cows at the end of the lactation period. Different approaches for identification of cows with IMI (i.e. often based on SCC) and targeted antimicrobial treatment of those rather than of all cows have been developed (i.e. selective dry cow treatment). Recently, DSCC representing the proportion of polymorphonuclear neutrophils and lymphocytes, has been introduced as an additional indicator for the presence of IMI. We used the last dairy herd improvement (DHI) samples taken within 42 d prior to dry-off as well as hand-stripped samples collected within 5 days prior to dry-off to measure DSCC and SCC. The bacteriological status was determined using quarter foremilk samples collected close to drying off. In total, 582 cows were dried off during our study but not all of them could be included in the data analysis for different reasons (e.g. incomplete data, samples too old for reliable determination of SCC and DSCC, contamination). Eventually, the final data set comprised of 310 cows of which 64 and 149 were infected with major and minor pathogens, respectively, and 97 were uninfected. The area under receiver-operating characteristics curves (AUC) were calculated to compare the diagnostic abilities of the different parameters. The AUC for identification of IMI by major pathogens when using the combination of DSCC and SCC was 0.64 compared to 0.62 for SCC alone and 0.62 for DSCC alone. The different parameters were further compared based on test characteristics and predictive values. For example, classifying cows as infected based on a cut-off of 200,000 cells/ml for SCC alone and in terms of using DSCC combined with SCC based on either >60% and/or >200,000 cells/ml, the sensitivity changed from 47 to 66% and the specificity from 74 to 54%. At the same time, the negative predictive value changed from 84 to 86% and the positive predictive value from 32 to 27%. Test characteristics and predictive values of the parameters DSCC and SCC were similar using DHI and hand-stripped samples. In conclusion, our study provides first indications on test characteristics and predictive values for the combination of DSCC and SCC. However, more work on this subject and the actual practical application is needed.


Assuntos
Doenças dos Bovinos/diagnóstico , Contagem de Células/veterinária , Glândulas Mamárias Animais/microbiologia , Mastite Bovina/diagnóstico , Animais , Bovinos , Doenças dos Bovinos/microbiologia , Contagem de Células/métodos , Feminino , Mastite Bovina/microbiologia , Sensibilidade e Especificidade
8.
Bioorg Med Chem Lett ; 29(23): 126717, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31635932

RESUMO

Fragment-based screening by SPR enabled the discovery of chemical diverse fragment hits with millimolar binding affinities to the peptidyl-prolyl isomerase Cyclophilin D (CypD). The CypD protein crystal structures of 6 fragment hits provided the basis for subsequent medicinal chemistry optimization by fragment merging and linking yielding three different chemical series with either urea, oxalyl or amide linkers connecting millimolar fragments in the S1' and S2 pockets. We successfully improved the in vitro CypD potencies in the biochemical FP and PPIase assays and in the biophysical SPR binding assay from millimolar towards the low micromolar and submicromolar range by >1000-fold for some fragment derivatives. The initial SAR together with the protein crystal structures of our novel CypD inhibitors provide a suitable basis for further hit-to-lead optimization.

9.
Clin Neuroradiol ; 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31486885

RESUMO

PURPOSE: To determine normative morphological and functional magnetic resonance (MR) neurography values in children and adolescents in correlation to demographic determinants. METHODS: In this study 29 healthy underage subjects (mean age 13.9 years, range 10-17 years) were examined using a standardized MR neurography protocol of the lumbosacral plexus and the right lower extremity at 3 T. Volumes of the dorsal root ganglia L3-S2, cross-sectional area of the sciatic and tibial nerves, as well as T2-weighted contrast nerve-muscle ratio and quantitative diffusion tensor imaging (DTI) values of the sciatic nerve were obtained and correlated with the demographic parameters sex, age, height and weight. RESULTS: While all obtained morphological and functional MR neurography values did not differ between male and female sex, dorsal root ganglia volume, sciatic and tibial nerve cross-sectional area correlated positively with age, height, and weight. The T2-weighted signal of the sciatic nerve was independent of demographic determinants. Negative correlation was found for fractional anisotropy (FA) with age, height, and weight, whereas radial diffusivity (RD) showed a positive correlation only with age. Mean diffusivity (MD) and axial diffusivity (AD) revealed no correlation with demographic determinants. CONCLUSION: The results of this study suggest that selection of sex-matched controls for further studies assessing peripheral nerve pathologies in underage patients may not be necessary; however, control subjects should be adapted to age, height, and weight of the patient population, especially if assessing dorsal root ganglia volume, nerve cross-sectional area and DTI.

10.
Nat Chem ; 11(11): 1058-1066, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31527847

RESUMO

Correlated motions of proteins are critical to function, but these features are difficult to resolve using traditional structure determination techniques. Time-resolved X-ray methods hold promise for addressing this challenge, but have relied on the exploitation of exotic protein photoactivity, and are therefore not generalizable. Temperature jumps, through thermal excitation of the solvent, have been utilized to study protein dynamics using spectroscopic techniques, but their implementation in X-ray scattering experiments has been limited. Here, we perform temperature-jump small- and wide-angle X-ray scattering measurements on a dynamic enzyme, cyclophilin A, demonstrating that these experiments are able to capture functional intramolecular protein dynamics on the microsecond timescale. We show that cyclophilin A displays rich dynamics following a temperature jump, and use the resulting time-resolved signal to assess the kinetics of conformational changes. Two relaxation processes are resolved: a fast process is related to surface loop motions, and a slower process is related to motions in the core of the protein that are critical for catalytic turnover.

11.
Nat Commun ; 10(1): 3562, 2019 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-31395886

RESUMO

Molecular chaperones such as Hsp40 and Hsp70 hold the androgen receptor (AR) in an inactive conformation. They are released in the presence of androgens, enabling transactivation and causing the receptor to become aggregation-prone. Here we show that these molecular chaperones recognize a region of the AR N-terminal domain (NTD), including a FQNLF motif, that interacts with the AR ligand-binding domain (LBD) upon activation. This suggests that competition between molecular chaperones and the LBD for the FQNLF motif regulates AR activation. We also show that, while the free NTD oligomerizes, binding to Hsp70 increases its solubility. Stabilizing the NTD-Hsp70 interaction with small molecules reduces AR aggregation and promotes its degradation in cellular and mouse models of the neuromuscular disorder spinal bulbar muscular atrophy. These results help resolve the mechanisms by which molecular chaperones regulate the balance between AR aggregation, activation and quality control.


Assuntos
Androgênios/metabolismo , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Receptores Androgênicos/metabolismo , Animais , Técnicas de Introdução de Genes , Células HEK293 , Humanos , Ligantes , Masculino , Camundongos , Camundongos Transgênicos , Ressonância Magnética Nuclear Biomolecular , Agregados Proteicos , Domínios Proteicos , Multimerização Proteica , Receptores Androgênicos/química , Receptores Androgênicos/genética , Solubilidade
12.
Radiology ; 292(1): 149-156, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31063079

RESUMO

Background Differential diagnosis between amyotrophic lateral sclerosis (ALS) and multifocal motor neuropathy (MMN) relies on clinical examination and electrophysiological criteria. Peripheral nerve imaging might assist this differential diagnosis. Purpose To assess diagnostic accuracy of MR neurography in the differential diagnosis of ALS and MMN. Materials and Methods This prospective study was conducted between December 2015 and April 2017. Study participants with ALS or MMN underwent MR neurography of the lumbosacral plexus, midthigh, proximal calf, and midupper arm of the clinically more affected side using high-resolution T2-weighted sequences. Matched healthy study participants who underwent MR neurography served as a control group. Two blinded readers independently rated fascicular lesions and muscle denervation signs on a five-point scale and made an image-only diagnosis, which was compared with the clinical diagnosis to assess diagnostic accuracy (reported for ALS vs non-ALS and MMN vs non-MMN). The Kruskal-Wallis test was used to compare readers' scoring results. Results Twenty-two participants with ALS (12 men and 10 women; mean age ± standard deviation, 62.3 years ± 9.0), eight participants with MMN (seven men and one woman; mean age, 57.6 years ± 18.6), and 15 healthy participants (seven men and eight women; mean age, 59.1 years ± 10.9) were enrolled in this study. Nerves of participants with ALS either appeared normal or showed T2-weighted hyperintensities without fascicular enlargement (reader 1, 22 of 22 participants; reader 2, 21 of 22 participants). In contrast, nerves in MMN were characterized by fascicular swellings (reader 1, six of eight participants; reader 2, seven of eight participants). Muscle denervation signs were more prominent in ALS than in MMN. Inter-rater reliability for blinded diagnosis was κ of 0.82. By consensus, the sensitivity to diagnose ALS (vs MMN and healthy control participants) was 19 of 22 (86% [95% confidence interval {CI}: 67%, 95%]). The corresponding specificity was 23 of 23 (100% [95% CI: 86%, 100%]). The sensitivity to diagnose MMN (vs ALS and healthy control participants) was seven of eight (88% [95% CI: 53%, 99%]). The corresponding specificity was 37 of 37 (100% [95% CI: 91%, 100%]). Conclusion MR neurography is an accurate method for assisting in the differential diagnosis of amyotrophic lateral sclerosis and multifocal motor neuropathy. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Andreisek in this issue.

13.
JMIR Serious Games ; 7(2): e10155, 2019 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-30964443

RESUMO

BACKGROUND: Medical education, in general, is undergoing a significant shift from traditional methods. It becomes very difficult to discover effective teaching methods within the limited possibilities in patient hands-on education, especially as seen in anesthesiology and intensive care medicine (AIM) teaching. Motivation-based teaching is very popular in all other aspects of education, but it has received scant attention in medical education literature, even though it can make a real difference for both students and physicians. OBJECTIVE: The primary aim of this retrospective audit was to find out if proper motivation-based teaching of students via the development of AKUTNE.CZ's serious games can help retain graduates of the Faculty of Medicine of Masaryk University (FMMU) for the AIM specialty. METHODS: Motivation-based teaching and the learning-by-doing concept were applied to a subject called Individual Project. Our topic, The Development of the Multimedia Educational Portal, AKUTNE.CZ, has been offered since 2010. The objective has been the development of supportive material in the form of interactive algorithms, serious games, and virtual patients for problem-based learning or team-based learning lectures aimed at acute medicine. We performed a retrospective questionnaire evaluation of all participants from the 2010-2017 period, focusing on their choice of medical specialty in 2017. The data were reported descriptively. RESULTS: We evaluated 142 students who passed Individual Project with topic The Development of the Multimedia Educational Portal, AKUTNE.CZ during 2010 to 2017. In this period, they developed up to 77 electronic serious games in the form of interactive multimedia algorithms. Out of 139 students in general medicine, 108 students (77.7%) had already graduated and 37 graduates (34.3%) worked in the AIM specialty. Furthermore, 57 graduates (52.8%) chose the same specialty after graduation, matching the topic of their algorithm, and 37 (65%) of these graduates decided to pursue AIM. CONCLUSIONS: Motivation-based teaching and the concept of learning-by-doing by the algorithm/serious game development led to the significant retention of FMMU graduates in the AIM specialty. This concept could be considered successful, and as the concept itself can also be well integrated into the teaching of other medical specialties, the potential of motivation-based teaching should be used more broadly within medical education.

14.
Neural Comput ; 31(5): 897-918, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30883275

RESUMO

Machine learning (ML) is a growing field that provides tools for automatic pattern recognition. The neuroimaging community currently tries to take advantage of ML in order to develop an auxiliary diagnostic tool for schizophrenia diagnostics. In this letter, we present a classification framework based on features extracted from magnetic resonance imaging (MRI) data using two automatic whole-brain morphometry methods: voxel-based (VBM) and deformation-based morphometry (DBM). The framework employs a random subspace ensemble-based artificial neural network classifier-in particular, a multilayer perceptron (MLP). The framework was tested on data from first-episode schizophrenia patients and healthy controls. The experiments differed in terms of feature extraction methods, using VBM, DBM, and a combination of both morphometry methods. Thus, features of different types were available for model adaptation. As we expected, the combination of features increased the MLP classification accuracy up to 73.12%-an improvement of 5% versus MLP-based only on VBM or DBM features. To further verify the findings, other comparisons using support vector machines in place of MLPs were made within the framework. However, it cannot be concluded that any classifier was better than another.


Assuntos
Encéfalo/diagnóstico por imagem , Diagnóstico por Computador/métodos , Imagem por Ressonância Magnética , Esquizofrenia/diagnóstico por imagem , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Reconhecimento Automatizado de Padrão/métodos
15.
Eur Radiol ; 29(7): 3480-3487, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30903330

RESUMO

OBJECTIVE: Detection and pattern analysis of fascicular nerve hyperintensities in the T2-weighted image are the backbone of magnetic resonance neurography (MRN) as they may represent lesions of various etiologies. The aim of this study was to assess the prevalence of fascicular nerve hyperintensities in healthy individuals with regard to a potential association with age or cerebral white matter lesions. METHODS: Sixty volunteers without peripheral nerve diseases between the age of 20 and 80 underwent MRN (high-resolution T2-weighted) of upper (median, ulnar, radial) and lower (sciatic, tibial) extremity nerves and a fluid-attenuated inversion recovery (FLAIR) sequence of the brain. Presence of peripheral nerve hyperintensities and degree of cerebral white matter lesions were independently rated by two blinded readers and related to each other and to age. T test with Welch's correction was used for group comparisons. Spearman's correlation coefficients were reported for correlation analyses. RESULTS: MR neurography revealed fascicular hyperintensities in 10 of 60 subjects (16.7%). Most frequently, they occurred in the sciatic nerve (8/60 subjects, 13.3%), less frequently in the tibial nerve at the lower leg and the median, ulnar, and radial nerves at the upper arm (1.7-5.0%). Mean age of subjects with nerve hyperintensities was higher than that of those without (60.6 years vs. 48.0 years, p = 0.038). There was only a weak correlation of nerve lesions with age and with cerebral white matter lesions, respectively. CONCLUSION: Fascicular nerve hyperintensities may occur in healthy individuals and should therefore always be regarded in conjunction with the clinical context. KEY POINTS: • MR neurography may reveal fascicular hyperintensities in peripheral nerves of healthy individuals. Fascicular hyperintensities occur predominantly in the sciatic nerve and older individuals. • Therefore, fascicular hyperintensities should only be interpreted as clearly pathologic in conjunction with the clinical context.


Assuntos
Imagem por Ressonância Magnética/métodos , Nervos Periféricos/patologia , Doenças do Sistema Nervoso Periférico/diagnóstico , Substância Branca/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Prospectivos , Adulto Jovem
16.
J Exp Biol ; 222(Pt 6)2019 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-30833459

RESUMO

Food processing refers to any form of mechanical breakdown of food prior to swallowing. Variations of this behaviour are found within all major gnathostome groups. Chewing is by far the most commonly used intraoral processing mechanism and involves rhythmic mandibular jaw and hyobranchial (tongue) movements. Chewing occurs in chondrichthyans (sharks and rays), actinopterygians (ray-finned fishes), dipnoi (lungfishes) as well as amniotes and involves similarities in the patterns of muscle activity and movement of the feeding apparatus. It has been suggested that amniote chewing, which involves the interaction of movements of the mandibular jaw and the muscular tongue, has evolved as part of the tetrapod land invasion. However, little is known about food-processing mechanisms in lissamphibians, which might have retained many ancestral tetrapod features. Here, we identified a processing mechanism in the salamandrid newt, Triturus carnifex, which after prey capture displays cyclic head bobbing in concert with rhythmic jaw and tongue movements. We used high-speed fluoroscopy, anatomical reconstructions and analyses of stomach contents to show that newts, although not using their mandibular jaws, deploy a derived processing mechanism where prey items are rasped rhythmically against the dentition on the mouth roof, driven by a loop motion of the tongue. We then compared patterns and coordination of jaw and tongue movements across gnathostomes to conclude that food processing in this newt species shares traits with processing mechanisms in fish as well as amniotes. This discovery casts salamanders as promising models for reconstructing the evolution of intraoral processing mechanisms at the fish-tetrapod split.

17.
J Magn Reson Imaging ; 50(4): 1251-1259, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30793419

RESUMO

BACKGROUND: The value of cerebral susceptibility-weighted imaging (SWI) in malignant melanoma (MM) patients remains controversial and the effect of melanin on SWI is not well understood. PURPOSE: To systematically analyze the spectrum of intracerebral findings in MM brain metastases (BM) on SWI and to determine the diagnostic value of SWI. STUDY TYPE: Retrospective. POPULATION/SUBJECTS: In all, 100 patients with melanoma BM (69 having received radiotherapy [RT] and 31 RT-naïve) and a control group of 100 melanoma patients without BM were included. For detailed analysis of signal characteristics, 175 metastases were studied. FIELD STRENGTH/SEQUENCE: Gradient echo SWI sequence at 1.5, 3.0, and 9.4 T. ASSESSMENT: Signal characteristics from melanotic and amelanotic BMs on SWI with a focus on blooming artifacts were analyzed, as well as the presence and longitudinal dynamics of isolated SWI blooming artifacts in patients with and without BM. STATISTICAL TESTS: Chi-squared and Student's t-test were used for contingency table measures and group data of signal and clinical characteristics, respectively. RESULTS: Melanotic and amelanotic metastases did not show significant differences of SWI blooming artifacts (38% vs. 43%, P = 0.61). Most metastases without an initial SWI artifact developed a signal dropout during follow-up (80%; 65/81). Isolated SWI artifacts were detected more frequently in patients with BM (20 vs. 9, P = 0.03), of which the majority were found in patients who had received RT (17 vs. 3, P = 0.08). None of these isolated SWI blooming artifacts turned into overt metastases over time (median follow-up: 8.5 months). Similar findings persisted as remnants of successfully treated metastases (88%; 7/8). DATA CONCLUSION: We conclude that SWI provides little additional diagnostic benefit over standard T1 -weighted imaging, as melanin content alone does not cause diagnostically relevant SWI blooming. Signal transition of SWI may rather indicate secondary phenomena like microbleeding and/or metal scavenging. Our results suggest that isolated SWI artifacts do not constitute vital tumor tissue but represent unspecific microbleedings, RT-related parenchymal changes or posttherapeutic remnants of former metastatic lesions. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:1251-1259.

18.
Neuroimage Clin ; 21: 101659, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30642759

RESUMO

PURPOSE: By applying diffusor tensor imaging (DTI) in patients with anterior interosseous nerve syndrome (AINS), this proof of principle study aims to quantify the extent of structural damage of a peripheral nerve at the anatomical level of individual fascicles. METHODS: In this institutional review board approved prospective study 13 patients with spontaneous AINS were examined at 3 Tesla including a transversal T2-weighted turbo-spin-echo and a spin-echo echo-planar-imaging pulse sequence of the upper arm level. Calculations of quantitative DTI parameters including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) for median nerve lesion and non-lesion fascicles as well as ulnar and radial nerve were obtained. DTI values were compared to each other and to a previously published dataset of 58 healthy controls using one-way Analysis of Variance with Bonferroni correction and p-values <.05 were considered significant. Receiver operating characteristic (ROC) curves were performed to assess diagnostic accuracy. RESULTS: FA of median nerve lesion fascicles was decreased compared to median nerve non-lesion fascicles, ulnar nerve and radial nerve while MD, RD, and AD was increased (p < .001 for all parameters). Compared to median nerve values of healthy controls, lesion fascicles showed a significant decrease in FA while MD, RD, and AD was increased (p < .001 for all parameters). FA of median nerve non-lesion fascicles showed a weak significant decrease compared to healthy controls (p < .01) while there was no difference in MD, RD, and AD. ROC analyses revealed an excellent diagnostic accuracy of FA, MD and RD in the discrimination of median nerve lesion and non-lesion fascicles in AINS patients as well as in the discrimination of lesion fascicles and normative median nerve values of healthy controls. CONCLUSION: By applying this functional MR Neurography technique in patients with AINS, this proof of principle study demonstrates that diffusion tensor imaging is feasible to quantify structural nerve injury at the anatomical level of individual fascicles.


Assuntos
Anisotropia , Imagem de Tensor de Difusão , Nervo Mediano/fisiopatologia , Nervo Ulnar/fisiopatologia , Adulto , Idoso , Braço/inervação , Imagem de Difusão por Ressonância Magnética/métodos , Imagem de Tensor de Difusão/métodos , Feminino , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Nervo Radial/fisiopatologia , Adulto Jovem
19.
Clin Neuroradiol ; 29(1): 19-26, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29030674

RESUMO

PURPOSE: To establish normal values and to identify demographic determinants of quantitative biomarkers in magnetic resonance neurography (MRN). METHODS: In this study 60 healthy individuals (5 men and 5 women of every decade between 20 and 80 years) were examined according to a standardized MRN protocol at 3 T, including multiecho T2 relaxometry. Nerve cross-sectional area (CSA), transverse relaxation time (T2), and proton spin density (PSD) were assessed for the sciatic, tibial, median, ulnar, and radial nerves. Correlation with demographic variables, such as height, weight, body mass index (BMI), and age was expressed by Pearson coefficients and t­tests were used to compare MRN biomarkers between men and women with and without normalization to body weight and BMI by linear regression. RESULTS: The average nerve CSA correlated moderately with height (r = 0.28, p = 0.04), weight (r = 0.40, p = 0.002), and BMI (r = 0.35, p = 0.008), but not with age (r = 0.23, p = 0.09). While T2 did not correlate with demographic parameters, PSD was strongly inversely associated with BMI (r = -0.64, p < 0.001) and weight (r = -0.557, p < 0.001). Sex-dependent differences in imaging marker values were found for CSA but became negligible after normalization to body weight. CONCLUSION: Quantitative biomarkers of MRN co-vary with demographic variables. As particularly important determinants, we identified body weight for nerve CSA and BMI for PSD. The presented normal values and demographic determinants may assist investigations into the potential of MRN biomarkers in further disease-specific studies.


Assuntos
Imagem por Ressonância Magnética/métodos , Nervos Periféricos/diagnóstico por imagem , Adulto , Fatores Etários , Idoso , Estatura , Índice de Massa Corporal , Peso Corporal , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Neuroimagem/métodos , Estudos Prospectivos , Nervo Radial/diagnóstico por imagem , Valores de Referência , Nervo Isquiático/diagnóstico por imagem , Fatores Sexuais , Nervo Tibial/diagnóstico por imagem , Nervo Ulnar/diagnóstico por imagem
20.
Stud Health Technol Inform ; 255: 222-226, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30306941

RESUMO

This paper presents the domain of information sciences, applied informatics and biomedical engineering, proposing to develop methods for an automated detection of similarities between two particular virtual learning environments - virtual patients at Akutne.cz and the OPTIMED curriculum management system - in order to provide support to clinically oriented stages of medical and healthcare studies. For this purpose, the authors used large amounts of text-based data collected by the system for mapping medical curricula and through the system for virtual patient authoring and delivery. The proposed text-mining algorithm for an automated detection of links between content entities of these systems has been successfully implemented by the means of a web-based toolbox.


Assuntos
Currículo , Educação Médica , Simulação de Paciente , Software , Algoritmos , Humanos , Aprendizagem , Realidade Virtual
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA