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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 13 (1969), S. 217-239 
    ISSN: 1432-0533
    Keywords: Peripheral Nerves ; Nerve Degeneration ; Nerve Regeneration Ageing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Durch kombinierte licht- und elektronenmikroskopische Untersuchung des N. suralis von 7 normalen menschlichen Probanden im Alter von 15–59 Jahren wird die altersabhängige Zunahme der Zahl degenerierender markhaltiger Fasern bestätigt. Eine früh im Verlauf des Lebens einsetzende Destruktion unbemarkter Fasern wird erstmals mitgeteilt. Die Verlaufsfolge in der Involution unbemarkter Fasern ist eine Sprossung ihrer Schwann-Zellen, die von fortschreitender Denervation und Axonsprossung gefolgt ist. Die Bedeutung der verschiedenen direkten und indirekten Hinweise auf die Schädigung von Nervenfasern wird diskutiert. Die Relevanz von Denervation und Regeneration von Fasern für die Erfassung pathologischer Veränderungen bei langsam fortschreitenden Schädigungen peripherer Nerven wird betont.
    Notes: Summary In a combined light and electron microscope study of sural nerves of seven normal individuals, aged between 15 and 59 years, the increase with age in the number of degenerating myelinated fibres is confirmed. Destruction of unmyelinated fibres starting early in life is reported for the first time. The sequence of events in the involution of unmyelinated fibres was found to be the budding of their Schwann cells followed by increasing evidence of their denervation and axonal sprouting. Comments are made on the value of several direct and indirect indices of destruction of nerve fibres. The relevance of denervation and regeneration of fibres in assessing pathological change in slowly progressive disorders of peripheral nerves is emphasised.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 13 (1969), S. 197-216 
    ISSN: 1432-0533
    Keywords: Peripheral Nerves ; Axons ; Myelin Sheaths ; Schwann Cells ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Eine kombinierte licht- und elektronenmikroskopische Untersuchung am normalen N. suralis von 7 Menschen im Alter von 15–59 Jahren wurde vorgenommen. Qualitative und quantitative Beobachtungen an Schwann-Zellen und Fibroblasten, markhaltigen und marklosen Fasern wurden an isolierten Faszikeln durchgeführt. Schwannzellen überwiegen gegenüber Fibroblasten im Verhältnis von etwa 9:1. Die meisten Schwannzellen (etwa 80%) liegen an marklosen Fasern. Die Faktoren, welche die Dichte dieser Zellen pro Querschnittsareal beeinflußen, werden diskutiert. Einige ultrastrukturelle Befunde an bemarkten Fasern werden beschrieben und ihre Zahl pro mm2 sowie die Häufigkeitsverteilung ihrer Dicke wird angegeben. Eine indirekte Methode zur Bestimmung der mittleren Internodienlänge für jede der Markfasergrößenpopulationen an Querschnitten von Faszikeln normaler Nerven durch Bestimmung des Verhältnisses der markhaltigen Fasersegmente zu ihrer Kernzahl wird vorgeschlagen. Die Ultrastruktur der marklosen Nervenfaern wird beschrieben und die Identifizierung dieser Axone mit extremen Durchmessern diskutiert. Ihre Dichte und Größenfrequenzhistogramme sind die ersten, die am Menschen durch systematische elektronenoptische Untersuchungen veröffentlicht werden. Das mittlere Verhältnis von marklosen zu bemarkten Fasern ist etwa 3,7:1 und schwankt in den Faszikeln der Einzelindividuen.
    Notes: Summary A combined light and electron microscope study of the normal sural nerve in 7 people aged 15–59 years is reported. Qualitative and quantitative studies of the Schwann cells and fibroblasts, myelinated and unmyelinated fibres are made in isolated fascicles. Schwann cells predominate over fibroblasts in the ratio of about 9-1. Most Schwann cells, almost 80%, are attached to unmyelinated fibres. Factors influencing the densities of these cells per cross sectional area are discussed. Some ultrastructural features of the myelinated fibres are described and their numbers per sq.mm and frequency distribution of their sizes are produced. An indirect method is proposed for assessing the mean internodal length for earch of the myelinated fibre size populations in cross sections of fascicles of normal nerves by estimating the proportion of myelinated segments cut through their nucleus. The ultrastructure of unmyelinated fibres is described and the identification of axons of extreme diameter is discussed. Their densities and size frequency histograms are the first to be reported in man by systematic electron microscope studies. The average ratio of unmyelinated to myelinated fibre density is about 3.7:1 though it varies in the fascicles of the different individuals. The implications of axonal diameter in the presence of myelin are commented on.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 246 (1999), S. 875-879 
    ISSN: 1432-1459
    Keywords: Key words Neuropathy ; Pain ; Sympathetic ; Iatrogenesis ; Pseudoneurology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The shifting paradigm of reflex sympathetic dystrophy–sympathetically maintained pains–complex regional pain syndrome is characterized by vestigial truths and understandable errors, but also unjustifiable lies. It is true that patients with organically based neuropathic pain harbor unquestionable and physiologically demonstrable evidence of nerve fiber dysfunction leading to a predictable clinical profile with stereotyped temporal evolution. In turn, patients with psychogenic pseudoneuropathy, sustained by conversion-somatization-malingering, not only lack physiological evidence of structural nerve fiber disease but display a characteristically atypical, half-subjective, psychophysical sensory-motor profile. The objective vasomotor signs may have any variety of neurogenic, vasogenic, and psychogenic origins. Neurological differential diagnosis of “neuropathic pain” versus pseudoneuropathy is straight forward provided that stringent requirements of neurological semeiology are not bypassed. Embarrassing conceptual errors explain the assumption that there exists a clinically relevant “sympathetically maintained pain” status. Errors include historical misinterpretation of vasomotor signs in symptomatic body parts, and misconstruing symptomatic relief after “diagnostic” sympathetic blocks, due to lack of consideration of the placebo effect which explains the outcome. It is a lie that sympatholysis may specifically cure patients with unqualified “reflex sympathetic dystrophy.” This was already stated by the father of sympathectomy, René Leriche, more than half a century ago. As extrapolated from observations in animals with gross experimental nerve injury, adducing hypothetical, untestable, secondary central neuron sensitization to explain psychophysical sensory-motor complaints displayed by patients with blatantly absent nerve fiber injury, is not an error, but a lie. While conceptual errors are not only forgivable, but natural to inexact medical science, lies particularly when entrepreneurially inspired are condemnable and call for peer intervention.
    Type of Medium: Electronic Resource
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  • 4
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    Unknown
    Madrid : Periodicals Archive Online (PAO)
    Emerita. 58 (1990) 255 
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  • 5
    facet.materialart.
    Unknown
    Madrid : Periodicals Archive Online (PAO)
    Emerita. 58 (1990) 146 
    ISSN: 0013-6662
    Topics: Classical Studies
    Description / Table of Contents: EDICIONES Y TÉCNICA FILOLÓGICA
    Notes: RESEÑA DE LIBROS
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric surgery international 1 (1986), S. 172-176 
    ISSN: 1437-9813
    Keywords: Lower esophageal sphincter ; Esophageal manometry ; Gastroesophageal junction LES competence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The high pressure zone (HPZ) is a result of a series of combative forces that converge in the gastroesophageal junction and contribute to generate the pressure barrier. Recognized factors in this function are the positive intra-abdominal pressure transmitted to the lower esophagus, thoracic suction, the diaphragmatic hiatus, the intrinsic lower esophageal sphincter, and the effect of gastric fundus acting on the distal esophagus through the His angle. The exclusive and quantitative role of the His angle is evaluated with the help of two experimental models (in vivo and in vitro) in the dog. By manometric procedures the gastric pressure at which the sphincter opens (OP) is studied under overloaded conditions, both in the living animal and in a gastroesophageal specimen, varying the His angle from 90° to 0°. In the “in vivo” model the pressure of the barrier with a His angle of 90° was 7.33 ± 3.4 mm Hg and the OP of 8.66 +- 4.1 mm Hg, while with the His angle at 0° the pressure of this barrier was 10.66 +- 2.9 mm Hg and the OP 16 +- 6.9 mm Hg (p 〈 0.05). In the “in vitro” model the His angle at 0° multiplied the OP two or three times. We conclude that the His angle at 0° allows transmission of the fundic pressure extrinsically to the sphincter, giving way to a higher OP, and increasing the degree of competence.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric surgery international 5 (1990), S. 106-109 
    ISSN: 1437-9813
    Keywords: Lower esophageal sphincter ; Gastroesophageal junction ; Esophageal manometry ; Experimental study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An important controversy exists concerning the adaptive capacity of the lower esophageal sphincter (LES) in response to increases in intragastric pressure. This capacity would characterize the LES as a dynamic element in preventing gastroesophageal reflux (GER). This physiological property was studied in 15 male cats using an experimental model in which the gastroesophageal antireflux barrier was generated eyclusively by the intrinsic tone of the LES. Under these conditions, the intragastric pressure (GP) and sphincter pressure (LESP) were measured by electromanometric procedures. When the gastric lumen was perfused with known volumes (25, 50, 75, 100, 125, 150 ml) of saline solution, increases in GP and LESP were observed. Both pressures increased slowly as the gastric volume rose, and when both values were equal, GER appeared. Studying the physiological properties of the LES by direct methods in this model, we conclude that (a) there is segmental pressure response of the LES when faced with direct opening stimulation such as an increase in GP; and (b) the increase in LES resting tone has a linear relation with the increase in GP.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-4943
    Keywords: Cactaceae ; proteins ; electrophoresis ; fluorescence ; calorimetry ; denaturation ; spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Characterization of three cactus proteins (native and denatured) from Machaerocereus gummosus (Pitahaya agria), Lophocereu schottii (Garambullo), and Cholla opuntia (Cholla), was based on electrophoretic, fluorescence, CD (circular dichroism), DSC (differential scanning calorimetry), and FT-IR (Fourier transform infrared) measurements. The obtained results of intrinsic fluorescence, DSC, and CD were dissimilar for the three species of cactus, providing evidence of differences in secondary and tertiary structures. Cactus proteins may be situated in the following order corresponding to their relative stability: Machaerocereus gummosus (Pitahaya agria) 〉 Cholla opuntia (Cholla) 〉 Lophocereu schottii (Garambullo). Thermodynamic properties of proteins and their changes upon denaturation (temperature of denaturation, enthalphy, and the number of ruptured hydrogen bonds) were correlated with the secondary structure of proteins and disappearance of α-helix.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-5117
    Keywords: Marine biotoxins ; red times ; harmful algal blooms ; domoic acid ; okadaic acid ; TTX
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previously considered as toxin-free, the Baja California Peninsula has witnessed several toxic algal blooms during the past three years. Apparently these ‘red-tide’ phenomena's outbreaks are not linked to any human related activity. This may just reflect better detection and training. Such events may be periodical and natural rather than induced. The most common types of marine toxins have been detected along the coast of the Peninsula and neighboring waters by mouse bioassay and chromatographic techniques. These are: Tetrodotoxin (TTX), Amnesic Shellfish Poison (ASP), Paralytic Shellfish Poisons (PSP), Diarrhetic Shellfish Poisons (DSP) and even Ciguatera (CFP), which are related to the presence of organisms of Prorocentrum sp. and Alexandrium sp. groups, and the diatom Pseudonitzschia sp. among others. There are also some indications about different kinds of TTX in the puffer fish of the region, and reasons to believe that we are facing a quite different pattern in toxic components, since PSP toxic potency (defined as the number of mouse units per gram(MU/g)of shellfish meat) is very high in spite of low dinoflagellates cell density registered. The ecological and social impact of the above has been considerable, with mass deaths of shellfish, seagulls, dolphins and turtles, and even some human casualties. The locally registered toxicity records: PSP found in one single fanshell reaches to 23 000 MU/100 g of tissue as determined by the mouse bioassay and, on a different event, two persons killed after ingesting puffer fish fillet. The largest reservoir of commercial marine organisms in Mexico is precisely the Northwest coast of the country and important plans for building large harbors and develop aquaculture areas are in progress. Therefore, a monitoring program is essential for an adequate management of such resources. Considering the large extension of the Peninsula (about1600 km)and, at this time, the lack of efficient communication means and scarce population, the implementation of such monitoring programs presents a big challenge.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 3 (1982), S. 783-785 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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