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  • 1
    ISSN: 1432-1920
    Keywords: Key words Magnetic resonance imaging ; Optic neuritis ; Multiple sclerosis ; Visual evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI of the optic nerves was obtained in 13 patients with acute optic neuritis and 13 with a previous optic neuritis (ON), assessed by clinical features, visual fields and visual evoked potentials. Results of the conventional short tau inversion recovery (STIR) sequence obtained with a short echo time (STE-STIR; 22 ms) were compared with those of a long echo time (LTE-STIR: 80 ms) sequence. The conventional STE-STIR sequence revealed lesions in the optic nerves in 78.5 % of acute and 58.8 % of previous ON. The LTE-STIR sequence showed abnormalities in 92.8 % of acutely symptomatic nerves and 94.1 % of nerves with previous ON. The optic nerve lesions appeared significantly longer with the LTE-STIR sequence than with the conventional STE-STIR sequences, in both acute and previous ON.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Optic neuritis ; Multiple sclerosis ; Visual evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI of the optic nerves was obtained in 13 patients with acute optic neuritis and 13 with a previous optic neuritis (ON), assessed by clinical features, visual fields and visual evoked potentials. Results of the conventional short tau inversion recovery (STIR) sequence obtained with a short echo time (STE-STIR; 22 ms) were compared with those of a long echo time (LTE-STIR: 80 ms) sequence. The conventional STE-STIR sequence revealed lesions in the optic nerves in 78.5% of acute and 58.8% of previous ON. The LTE-STIR sequence showed abnormalities in 92.8% of acutely symptomatic nerves and 94.1% of nerves with previous ON. The optic nerve lesions appeared significantly longer with the LTE-STIR sequence than with the conventional STE-STIR sequences, in both acute and previous ON.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1432
    Keywords: Cyanelles ; Cyanophora paradoxa ; Endosymbiosis ; Evolution ; Glaucocystophyta ; Glaucophyta ; Phylogeny ; Plastid ; 16S ribosomal RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glaucocystophyte algae (sensu Kies, Berl. Deutsch. Bot. Ges. 92, 1979) contain plastids (cyanelles) that retain the peptidoglycan wall of the putative cyanobacterial endosymbiont; this and other ultrastructural characters (e.g., unstacked thylakoids, phycobilisomes) have suggested that cyanelles are “primitive” plastids that may represent undeveloped associations between heterotrophic “host” cells (i.e., glaucocystophytes) and cyanobacteria. To test the monophyly of glaucocystophyte cyanelles and to determine their evolutionary relationship to other plastids, complete 16S ribosomal RNA sequences were determined for Cyanophora paradoxa, Glaucocystis nostochinearum, Glaucosphaera vacuolata, and Gloeochaete wittrockiana. Plastid rRNAs were analyzed with the maximum-likelihood, maximumparsimony, and neighbor joining methods. The phylogenetic analyses show that the cyanelles of C. paradoxa, G. nostochinearum, and G. wittrockiana form a distinct evolutionary lineage; these cyanelles presumably share a monophyletic origin. The rDNA sequence of G. vacuolata was positioned within the nongreen plastid lineage. This result is consistent with analyses of nuclear-encoded rRNAs that identify G. vacuolata as a rhodophyte and support its removal from the Glaucocystophyta. Results of a global search with the maximumlikelihood method suggest that cyanelles are the first divergence among all plastids; this result is consistent with a single loss of the peptidoglycan wall in plastids after the divergence of the cyanelles. User-defined tree analyses with the maximum-likelihood method indicate, however, that the position of the cyanelles is not stable within the rRNA phylogenies. Both maximumparsimony and neighbor-joining analyses showed a close evolutionary relationship between cyanelles and nongreen plastids; these phylogenetic methods were sensitive to inclusion/exclusion of the G. wittrockiana cyanelle sequence. Base compositional bias within the G. wittrockiana 16S rRNA may explain this result. Taken together the phylogenetic analyses are interpreted as supporting a near-simultaneous radiation of cyanelles and green and nongreen plastids; these organelles are all rooted within the cyanobacteria.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0819
    Keywords: Zoned magma body ; Chemical variation ash-flow sheets ; Tephra sequence ; Differentiation time constraints ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Rainier Mesa ash-flow is a large (1200 km3), 11.6 My old, chemically zoned unit that ranges in composition from 55 to 76% SiO2 — one of the largest chemical ranges ever observed in a large volume ash-flow sheet. Two chemical trends occur in this sheet, a low silica (55–66% SiO2) and a high silica (〉66% SiO2) trend. Ninety per cent of the Rainier Mesa sheet occurs in the high silica trend. Immediately beneath the Rainier Mesa sheet is a thick tephra sequence. The chemical variation of this sequence is nearly equivalent to the high silica portion of the Rainier Mesa ash-flow sheet (about 66–78% SiO2). Throughout the tephra sequence numerous small ash-flow layers occur, and each ash-flow layer is chemically zoned from more evolved at the base to less evolved at the top. This is consistent with having been erupted from a zoned magma body. The lowest silica tephra units are at the base of the sequence and the highest silica units are at the top — that is, the large-scale chemical trend of the entire sequence is opposite to that of the individual ash-flow layers. These ash-flow layers are of very small volume. The tephra sequence provides a unique record of the incremental development of the zoned, high silica portion of the Rainier Mesa magma body.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0819
    Keywords: Key wordsZoned magma body ; Chemical variation ; ash-flow sheets ; Tephra sequence ; Differentiation ; time constraints ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Rainier Mesa ash-flow is a large (1200 km3), 11.6 My old, chemically zoned unit that ranges in composition from 55 to 76% SiO2– one of the largest chemical ranges ever observed in a large volume ash-flow sheet. Two chemical trends occur in this sheet, a low silica (55–66% SiO2) and a high silica (〉66% SiO2) trend. Ninety per cent of the Rainier Mesa sheet occurs in the high silica trend. Immediately beneath the Rainier Mesa sheet is a thick tephra sequence. The chemical variation of this sequence is nearly equivalent to the high silica portion of the Rainier Mesa ash-flow sheet (about 66–78% SiO2). Throughout the tephra sequence numerous small ash-flow layers occur, and each ash-flow layer is chemically zoned from more evolved at the base to less evolved at the top. This is consistent with having been erupted from a zoned magma body. The lowest silica tephra units are at the base of the sequence and the highest silica units are at the top – that is, the large-scale chemical trend of the entire sequence is opposite to that of the individual ash-flow layers. These ash-flow layers are of very small volume. The tephra sequence provides a unique record of the incremental development of the zoned, high silica portion of the Rainier Mesa magma body.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-072X
    Keywords: Eubacterium ; Thermophile ; Evolution ; Fervidobacterium ; Lipids ; Thermotoga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An extremely thermophilic anaerobic fermentative eubacterium growing at temperatures between 50 and 80°C (opt.: 65°C) was isolated from an Icelandic hot spring. The cells were Gram-negative motile rods, about 1.8 μm in length, and 0.6 μm in width occurring singly and in pairs. About 50% of the cells formed large spheroids at one end similar to Fervidobacterium nodosum. The new isolate H 21 differed from Fervidobacterium nodosum by a 6 mol % higher GC-content of its DNA (41 mol %), its ability to grow on cellulose, and insignificant DNA homology. The lipids of isolate H 21 were similar to that of members of “Thermotogales”. 16S rRNA sequencing of isolate H 21 and Fervidobacterium nodosum indicated (a) that isolate H 21 represents a new species of the genus Fervidobacterium which we name Fervidobacterium islandicum and (b) that the genus Fervidobacterium belongs to the “Thermotogales” branch.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-072X
    Keywords: Evolution ; Eubacteria ; Thermophile ; Anaerobe ; Thermotoga maritima
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel type of bacterium has been isolated from various geothermally heated locales on the sea floor. The organisms are strictly anaerobic, rod-shaped, fermentative, extremely thermophilic and grow between 55 and 90°C with an optimum of around 80°C. Cells show a unique sheath-like structure and monotrichous flagellation. By 16S rRNA sequencing they clearly belong to the eubacteria, although no close relationship to any known group could be detected. The majority of their lipids appear to be unique in structure among the eubacteria. Isolate MSB8 is described as Thermotoga maritima, representing the new genus Thermotoga.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1590-3478
    Keywords: Visual evoked potentials ; VEP ; Optic neuritis ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario I 20 pazienti affetti da Neurite Ottica (NO), descritti nel precedente lavoro [23] sono stati sottoposti a registrazioni seriali multicanali dei Potenziali Evocati Visivi (PEV), per un periodo di 2 anni dall'esordio della NO. I PEV potevano correlare con le lesioni evidenziate con la Risonanza Magnetica, con le alterazioni campimetriche e con altri reperti clinici. Basandoci sulla loro distribuzione in mappa, i PEV sono stati classificati come realmente “ritardati” e “pseudo-ritardati”. PEV realmente “ritardati” potevano essere registrati all'esordio, o precocemente dopo l'episodio di NO, e la presenza del “ritardo” stava ad indicare un recupero della funzione visiva e, quindi, una prognosi fausta. Gli “pseudo-ritardi” indicavano un'alterazione del campo visivo a prognosi non favorevole per un recupero della funzione visiva, a meno che entro i primi 3 mesi dalla NO si fosse verificata una ricomparsa di componenti normali o “ritardate”. Gli “pseudo-ritardi” erano rilievi caratteristici nei pazienti con lesioni maggiormente lunghe alle immagini LTE-STIR MRI [23]. Nessuna correlazione è stata trovata tra latenza dei PEV e lunghezza delle placche. I nostri rilievi sono in disaccordo con precedenti teorie relative ai tempi di instaurazione-recupero delle alterazioni di conduzione nella NO e nella Sclerosi Multipla.
    Notes: Abstract Twenty patients with optic neuritis (ON) described in the previous study [23] underwent serial VEP recordings (using multiple electrode arrays) for two years. The VEPs could be correlated with the lesions revealed by MRI, Visual Field tests and other clinical findings. On the basis of their scalp distribution, they were classified as “really delayed” VEPs and “pseudo-delayed” VEPs. Real delays could be recorded at the onset of ON or shortly afterwards, and their appearance indicated the recovery of visual function and a good prognosis. Pseudo-delays indicated an alteration in the visual field and, unless a breakthrough of normal or delayed components appeared in the first three months, following acute ON, indicate a poor prognosis for the recovery of visual function. The pseudo-delayed VEPs were mainly observed in patients with longer lesions revealed by means of LTE-STIR MRI [23]; there was no correlation between VEP latency and the length of plaques. Our findings contradict previous theories on the timing of conduction alterations in ON and multiple sclerosis.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1590-3478
    Keywords: MRI ; Optic neuritis ; Multiple sclerosis ; VEP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario Si descrivono i risultati ottenuti con indagini di Risonanza Magnetica (RM) dei nervi ottici (eseguite all'esordio e 12 mesi dopo) in 20 pazienti affetti da Neurite Ottica (NO) acuta, valutata in funzione della sintomatologia clinica e delle alterazioni campimetriche e del potenziale evocato visivo. Sono state analizzate le immagini RM in Short Tau Inversion Recovery (STIR) mettendo a confronto i rilievi ottenuti con sequenza Short Time Echo (STE-STIR: 22 msec) rispetto a quelli ottenuti con Long Time Echo (LTE-STIR: 20 msec). Mentre con la convenzionale STE-STIR è stato possibile rilevare lesioni a carico dei nervi ottici nel 57.2% delle Neuriti Acute e nel 42.9% delle Neuriti Pregresse, la metodica LTE-STIR è risultata diagnostica nel 95.2% delle Neuriti Acute e nel 85% delle Neuriti Pregresse. Sia nelle NO acute che nelle pregresse, la lunghezza delle lesioni a carico dei nervi ottici sono risultate significativamente maggiori rispetto a quelle ottenute con la convenzionale metodica STE-STIR.
    Notes: Abstract Magnetic resonance images of optic nerves were obtained in 20 patients with acute optic neuritis (ON), and assessed by means of clinical, visual field and visual evoked potential evaluations; the imaging was repeated 1 year later. The results of the conventional Short Tau Inversion Recovery (STIR) sequence obtained using short time echo (STE-STIR: 22 msec) were compared with those of the long time echo sequence (LTE-STIR: 80 msec). The conventional STE-STIR sequence revealed lesions in 57.2% cases of acute ON and in 42.9% of the optic nerves affected by previous ON: the LTE-STIR sequence was diagnostic in 95.2% of acute ON cases and in 85% of patients with previous ON. The calculated length of the optic nerve lesions was significantly longer in the images obtained using the LTE-STIR sequence than in those obtained using conventional STE-STIR sequences.
    Type of Medium: Electronic Resource
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