1,721,003 research outputs found
Association of the mtDNA m.4171C>A/MT-ND1 mutation with both optic neuropathy and bilateral brainstem lesions
Full text linkBackground: An increasing number of mitochondrial DNA (mtDNA) mutations, mainly in complex I genes, have
been associated with variably overlapping phenotypes of Leber’s hereditary optic neuropathy (LHON),
mitochondrial encephalomyopathy with stroke-like episodes (MELAS) and Leigh syndrome (LS). We here describe
the first case in which the m.4171C>A/MT-ND1 mutation, previously reported only in association with LHON, leads
also to a Leigh-like phenotype.
Case presentation: A 16-year-old male suffered subacute visual loss and recurrent vomiting and vertigo associated
with bilateral brainstem lesions affecting the vestibular nuclei. His mother and one sister also presented subacute
visual loss compatible with LHON. Sequencing of the entire mtDNA revealed the homoplasmic m.4171C>A/MT-ND1
mutation, previously associated with pure LHON, on a haplogroup H background. Three additional non-synonymous
homoplasmic transitions affecting ND2 (m.4705T>C/MT-ND2 and m.5263C>T/MT-ND2) and ND6 (m.14180T>C/MT-ND6)
subunits, well recognized as polymorphisms in other mtDNA haplogroups but never found on the haplogroup H
background, were also present.
Conclusion: This case widens the phenotypic expression of the rare m.4171C>A/MT-ND1 LHON mutation, which
may also lead to Leigh-like brainstem lesions, and indicates that the co-occurrence of other ND non-synonymous
variants, found outside of their usual mtDNA backgrounds, may have increased the pathogenic potential of the
primary LHON mutation
Re: Pilat et al.: High-resolution imaging of the optic nerve and retina in optic nerve hypoplasia (Ophthalmology 2015;122:1330-9)
No full textAccuracy of Funduscopy to Identify True Edema versus Pseudoedema of the Optic Disc.
No full textPurpose: Differential diagnosis between acute optic disc edema (ODE) and optic disc pseudo-edema (PODE) may be a clinical challenge even for well-trained ophthalmologists. Funduscopy remains the first-line investigation. The aim of this study was to assess the accuracy, sensitivity, and specificity of funduscopy in differentiating ODE from PODE. Methods: Observational, cross-sectional, two-center study of subjects referred for presumed acute ODE. During funduscopy each observer completed a form concerning the presence/absence of the ten conventional signs of ODE. 74 patients with ODE and 48 subjects with PODE were included in the analysis. Accuracy, sensitivity, and specificity from all possible combinations of signs were calculated by Support Vector Machine (SVM) analysis. Results: As a single sign, the swelling of the peripapillary retinal nerve fiber layer had the highest accuracy (0.92; 95% CI: 0.82–0.97). Little variation was observed when more than fours signs were present; the best four-sign combination was: SWELLING, HEMORRHAGES, papilla ELEVATION, and CONGESTION of peripapillary vessels (accuracy = 0.93, 95% CI: 0.83–0.98; sensitivity = 0.95; and specificity = 0.89). The presence of retinal and/or choroidal folds appeared to be a pathognomonic sign of true ODE (100% of sensitivity), but with a low rate of presentation (23%). Conclusions: The presence of at least four ophthalmoscopic signs (with the sign “swelling” included) gives the highest accuracy. Furthermore, peripapillary retinal folds seem to be related exclusively to ODE, since they were never observed in our PODE group. These data may be useful for clinicians when evaluating patients referred for presumed optic disc edema in the acute phase
Human extraocular muscles in mitochondrial diseases: comparing Chronic Progressive External Ophthalmoplegia with Leber's Hereditary Optic Neuropathy
No full textAims: To compare the ultrastructural aspects of human
extraocular muscles in two types of mitochondrial disease:
chronic progressive external ophthalmoplegia (CPEO) and
Leber’s hereditary optic neuropathy (LHON).
Methods: Muscle samples of the medial rectus obtained from
surgery in a sporadic case of CPEO associated with deleted
mitochondrial DNA, and post mortem in a case of 3460/
ND1 LHON were processed for electron microscopy (EM).
The medial rectus from an autoptic time to fixation matched
control was used to exclude postmortem artefacts.
Results: The CPEO specimen revealed focal areas of disruption
and abnormalities of mitochondria in some muscle
fibres, creating a ‘‘mosaic-like’’ pattern. In the LHON
specimen a diffuse increase in both number and size of
mitochondria (mean diameter 0.85 mm v 0.65 mm of control,
p,0.0001) with swollen appearance and disorganised
cristae filled all spaces of sarcoplasmic reticulum. In some
areas the excessive number of mitochondria slightly distorted
myofibrils.
Conclusion: EM investigation of extraocular muscles in CPEO
and LHON reveals marked differences. A ‘‘mosaic-like’’
pattern caused by a selective damage of muscle fibres was
evident in CPEO, whereas a diffuse increase in mitochondria
with preservation of myofibrils characterised the LHON case.
These ultrastructural changes may relate to the different
expression of the two diseases, resulting in ophthalmoplegia
in CPEO and normal eye movements in LHON
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
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
- …
