1,721,014 research outputs found
Atrophy-resistant fibers in permanent peripheral denervation of human skeletal muscle
No full textNeurol Res. 2008 Mar;30(2):137-44.
Atrophy-resistant fibers in permanent peripheral denervation of human skeletal muscle.
Biral D, Kern H, Adami N, Boncompagni S, Protasi F, Carraro U.
Source
Italian C.N.R. Institute of Neuroscience, and Laboratory of Translational Myology, Interdepartmental Research Center of Myology, c/o Department of Biomedical Sciences, University of Padova, I-35121 Padova, Italy.
Abstract
OBJECTIVE:
Human muscle fibers usually undergo severe atrophy/degeneration as a result of long-term peripheral denervation. However, some biopsies from paraplegic patients suffering complete conus cauda syndrome display the presence of a small percentage of muscle fibers with a very large diameter (big fibers). The objective of the present study is to determine if these big fibers are the result of residual innervation/reinnervation, or if instead they are fibers resistant to atrophy.
METHODS:
Human muscle biopsies were harvested from the vastus lateralis of spinal cord injury (SCI) patients affected by complete lower motor neuron lesion (LML). The specimens were either processed for light microscopy or embedded for electron microscopy (EM).
RESULTS:
Our results indicate that the big fibers are neither the results of residual innervation or sparse reinnervation. In spite of the fact that the extrasynaptic NCAM immunostaining disappear a few months after SCI, the big fibers are characterized by positive molecular markers of denervation, that is, the differential labeling of their dystrophin molecule by anti-C and anti-N terminals antibodies. Furthermore, the EM analysis shows that these cells present the peculiar ultrastructural disarrangements of the contractile apparatus and of the internal membrane systems characteristic of 'peripheral denervation'. No fibers presenting large areas of cross-striation were found. The EM analysis provides the final evidence that these big fibers are muscle fibers which are indeed denervated, very different from normal and/or disused (e.g. upper motor neuron lesion) muscle fibers.
DISCUSSION:
Although these large muscle fibers are surprisingly more frequent in human muscle biopsies after 3 years from SCI than earlier, it remains to be determined whether their presence in some biopsies but not in others is caused by sampling, or is related to other factors such as to subjects' background genetics, or the extent of passive stretching induced by different rehabilitation strategies.
PMID:
18397604
[PubMed - indexed for MEDLINE
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
One year of home-based daily functional electrical stimulation (FES) in complete lower motor neuron paraplegia: recovery of tetanic contractility drives the structural improvements of denervated muscle
No full textNeurol Res. 2010 Feb;32(1):5-12.
One year of home-based daily FES in complete lower motor neuron paraplegia: recovery of tetanic contractility drives the structural improvements of denervated muscle.
Kern H, Carraro U, Adami N, Hofer C, Loefler S, Vogelauer M, Mayr W, Rupp R, Zampieri S.
Source
Ludwig Boltzmann Institute of Electrostimulation and Physical Rehabilitation, Department of Physical Medicine, Wilhelminenspital, Vienna, Austria.
Abstract
OBJECTIVE:
Spinal cord injury (SCI) causes muscle atrophy, which is particularly severe, due to inability to perform tetanic contractions, when lower motor neurons (LMN) are involved. We performed a longitudinal study in 25 Europeans suffering from complete conus cauda syndrome from 0.7 to 8.7 years comparing functional and structural thigh muscle properties before and after 2 years of home-based daily training by functional electrical stimulation (FES). The mid-term results after 1 year and preliminary muscle biopsy observations at project end-point from a subset of subjects are here reported.
METHODS:
Muscles were electrically stimulated at home by means of large surface electrodes and a custom-designed stimulator. The poor excitability of the LMN denervated muscles was first improved by twitch-contraction training. Then, tetanic contractions against progressively increased loading were elicited. Finally, standing-up exercises were daily performed. The bulk of thigh muscle was estimated by transverse computer tomography (CT) scan and force measurements. Needle biopsies of vastus lateralis were harvested before and after 2 years of FES.
RESULTS:
The 1 year home-based daily FES training induced: (1) very similar increases in muscle excitability and contractility in right and left legs; (2) feasibility to elicit tetanic contractions by means of train-stimulation with about ten times improvement of muscle force; (3) increase in the 26% of muscle bulk, as shown by CT scan analyses, improving appearance of limbs and muscle cushioning; (4) myofiber size increase (+94%) in a small series of muscle biopsies obtained after 2 years of FES. None of the subjects that performed 1 year home-based daily FES training (20 persons) had worsened their functional class, while 20% (4/20) improved to functional class 4, that is, the ability to stand.
DISCUSSION:
The European Union (EU) Project Rise shows that 'home-based daily FES training' is a safe and effective therapy that may maintain life-long physical exercise by active muscle contraction (FES is the only option for denervated muscle) as a procedure to recover the early-lost tetanic contractility of denervated muscle, and to counteract muscle atrophy in order to prevent clinical complications.
PMID:
20092690
[PubMed - indexed for MEDLINE
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Subclinical myopathy in patients affected with newly diagnosed colorectal cancer at clinical onset of disease: evidence from skeletal muscle biopsies.
No full textNeurol Res. 2010 Feb;32(1):20-5. Epub 2009 Nov 26.
Subclinical myopathy in patients affected with newly diagnosed colorectal cancer at clinical onset of disease: evidence from skeletal muscle biopsies.
Zampieri S, Doria A, Adami N, Biral D, Vecchiato M, Savastano S, Corbianco S, Carraro U, Merigliano S.
Source
Laboratory of Translational Myology, Interdepartmental Research Center of Myology, c/o, Department of Biomedical Science, University of Padova, Padova, Italy. [email protected]
Abstract
OBJECTIVE:
To evaluate skeletal muscle biopsy from asymptomatic patients affected with newly diagnosed colorectal cancer and to identify pathological features which may be indicative of tumor-associated muscle disorders, potentially leading to cachexia.
METHODS:
Patients affected with newly diagnosed colorectal cancer at clinical onset of disease underwent biopsy of the rectus abdominis muscle during elective laparoscopic tumor resection, before chemotherapeutic treatment. Morphometric analyses, ATPase histochemistry and immunohistochemical studies using antibodies directed to N-CAM and to MHC-emb, two sound makers of muscle denervation and injury-induced muscle regeneration, were performed on intraoperative muscle biopsies from ten patients. Muscle biopsies from rectus abdominis of seven subjects affected with non-neoplastic condition, which underwent laparoscopic surgery, were used as controls.
RESULTS:
In patients' biopsies, we observed a surprisingly high percentage of myofibers with internalized or central nuclei compared to controls (9.15 +/- 8.9 versus 0.6 +/- 0.9, p<0.0003). In addition, in the 30% of patients, small myofibers expressing the MHC-emb have been identified (0.4 +/- 0.5 positive fibers/mm(2)), while in 50% of patients, larger fibers positive for N-CAM have also been detected (0.7 +/- 1.1 positive fibers/mm(2)), suggesting that investigated muscle biopsies exhibit other evidence of muscle fiber injury/regeneration and/or denervation. Among the 10,000 analysed myofibers in control biopsies, no MHC-emb and N-CAM-positive muscle fibers have been detected. Thus, patients affected with newly diagnosed colorectal cancer at clinical onset of disease display early signs of a subclinical myopathy.
DISCUSSION:
Factors and mechanisms of this cancer-associated myopathy are yet unknown. The facts that the great majority of the abnormally nucleated myofibers are of the fast type and that regenerating myofibers are present, suggest a myogenic response to the colorectal cancer and not to the laparoscopic modalities of the biopsy harvesting. Follow-up of the patients will elucidate the clinical relevance of our observation, and further studies investigating the molecular mechanism underlying this early cancer-associated myopathy will hopefully provide some pathogenetic clues leading to the identification of potential specific targets for therapeutic intervention to prevent tumor cachexia.
PMID:
19941733
[PubMed - indexed for MEDLINE
Image forgery detection: a survey of recent deep-learning approaches
Full text linkIn the last years, due to the availability and easy of use of image editing tools, a large amount of fake and altered images have been produced and spread through the media and the Web. A lot of different approaches have been proposed in order to assess the authenticity of an image and in some cases to localize the altered (forged) areas. In this paper, we conduct a survey of some of the most recent image forgery detection methods that are specifically designed upon Deep Learning (DL) techniques, focusing on commonly found copy-move and splicing attacks. DeepFake generated content is also addressed insofar as its application is aimed at images, achieving the same effect as splicing. This survey is especially timely because deep learning powered techniques appear to be the most relevant right now, since they give the best overall performances on the available benchmark datasets. We discuss the key-aspects of these methods, while also describing the datasets on which they are trained and validated. We also discuss and compare (where possible) their performance. Building upon this analysis, we conclude by addressing possible future research trends and directions, in both deep learning architectural and evaluation approaches, and dataset building for easy methods comparison
QUIC Employment: Comparing the Response Time of Facebook and Twitter
No full textTCP has been the most reliable transport layer protocol, used on the Internet since 1974, thanks to its ordered and error-checked delivery, stateful property and retransmission property. The most relevant drawback is the high latency, meaning a connection that does not require a reliable delivery can use UDP, another transport layer protocol, slimmer than TCP, which provides a connectionless datagram service prioritizing time over reliability. During these years, researchers have worked on new protocols in the attempt of decreasing page load time without sacrificing reliability. Even Google proposed a solution, the Quick UDP Internet Connection (QUIC) protocol, born in 2013. Since QUIC is a very recent protocol, this paper could help to further understanding its employment and performance in typical scenarios such as, for instance, when considering major social networks such as Facebook and Twitter, with only the former employing QUIC. In particular, we have measured the response time of the two applications when considering different network conditions. Our preliminary results could be used to generate traffic models and, partially, to advocate the use of QUIC
Severely atrophic muscle fibers with nuclear clumps survive many years in permanently denervated human muscle.
No full textThe Open Pathology Journal 2009; 3: 106-110. Severely atrophic muscle fibers with nuclear clumps survive many years in permanently denervated human muscle
Helmut Kern, MD,1 Ugo Carraro, MD,2 Donatella Biral, DBiol,3 Nicoletta Adami, DBiol,2 and Sandra Zampieri, DBiol, PhD4
1 Ludwig Boltzmann Institute of Electrostimulation and Physical Rehabilitation, Department of Physical Medicine, Wilhelminenspital. A-1171 Vienna, Austria.
2 Laboratory of Translational Myology of the Interdepartmental Research Center of Myology, c/o Department of Biomedical Science, University of Padova, I-35121 Padova, Italy.
3 C.N.R. Institute of Neuroscience c/o Department of Biomedical Science, University of Padova, I-35121 Padova, Italy.
4 Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Italy
Abstract
After complete lumbar-ischiatic spinal cord injury (SCI) the lower motor neuron (LMN) denervated human muscle fibers lose completely the myofibrillar apparatus and the coil distribution of myonuclei that are relocated in groups (nuclear clumps) in the center of these “severely atrophic” muscle fibers. In our cohort of patients, the “severely atrophic” myofibers are frequent in muscle biopsies harvested three to six years after SCI. Up to two years of LMN denervation the muscle fibers with nuclear clumps are 2±5 % (mean ±SD) of the total muscle fibers. The percentage increases to 27±9 % between three and six years of denervation (p< 0.001), and then abruptly decrease from the 6th year of LMN denervation onward, when fibrosis takes over to neurogenic muscle atrophy. Immunohistochemical analyses show that nuclear grouping occurs in both fast and slow muscle fibers. These results show that human muscle fibers survive permanent denervation much longer than generally accepted
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