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  • 1
    ISSN: 1433-8491
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The thermoresistant gluconate kinase GntK from Escherichia coli, an essential enzyme in gluconate metabolism, has been expressed, purified and crystallized. For crystallization, the hanging-drop vapour-diffusion method was used with polyethylene glycol (PEG) 6000 and lithium chloride as precipitants. Three crystal forms belonging to the monoclinic space group C2 or the orthorhombic space groups P212121 and P21212 were obtained. The unit-cell parameters are a = 75.0, b = 79.3, c = 70.2 Å, β = 105.3° (C2), a = 52.0, b = 79.3, c = 89.8 Å (P212121) and a = 70.1, b = 74.1, c = 78.9 Å (P21212). In all three crystal forms, there are two molecules in the asymmetric unit; the different forms occur in the same crystallization drop. The crystals diffract to at least 2.0 Å using synchrotron radiation.
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  • 3
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Tyrosine feedback-inhibits the 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase isoenzyme AroF of Escherichia coli. Here we show that an Asn-8 to Lys-8 substitution in AroF leads to a tyrosine-insensitive DAHP synthase. This mutant enzyme exhibited similar activities (v=30–40 U mg−1) and substrate affinities (Kmerythrose-4-phosphate=0.5 mM, positive cooperativity with respect to phospho(enol)pyruvate) as the wild-type AroF, but showed decreased thermostability. An engineered AroF enzyme lacking the seven N-terminal residues also was tyrosine-resistant. These results strongly suggest that the N-terminus of AroF is involved in the molecular interactions occurring in the feedback-inhibition mechanism.
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  • 4
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of competition for macroelements with bacteria from ditch water on the parathion-hydrolyzing Flavobacterium sp. ATCC 27551 (FB) was investigated within mixed continuous cultures under carbon-, nitrate- or phosphate-limited conditions. The high initial rate of parathion hydrolysis decreased rapidly in all cultures due to the loss of strain FB. Addition of 2-isopropyl-6-methyl-4-pyrimidinol (a selective source of carbon, nitrogen and energy for FB) to one nitrate- and carbon-limited chemostat caused a 20-fold increase in parathion-hydrolyzing activity compared to unamended control cultures and retention of FB. The presence of the parathion hydrolase-encoding gene could be demonstrated by a newly developed PCR detection method in all FB cultures during most of the cultivation period. These results suggest that competition effects cause the pesticide-degrading capacity of microbial communities depending on their frequency of exposure to the pesticide compounds.
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  • 5
    ISSN: 1573-7284
    Keywords: Campylobacter ; Gastroenteritis ; Population-based ; Salmonella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to estimate the incidence of gastroenteritis and Campylobacterand Salmonellainfection in the Dutch population, the disease burden, and the percentage of patients with gastroenteritis that consults a general practitioner. A sample of 6243 persons was invited to participate in the study, i.e. completing a questionnaire and submitting stool samples. The follow-up period was 17 weeks. In total, 2206 persons participated (= 35%), contributing 660 person years. The incidence (standardised by age and gender) of first episodes of gastroenteritis was 45 per 100 person years. Among patients with gastroenteritis, Salmonellaand Campylobacterwere cultured in 1.6 and 4.5%, respectively. The standardised incidence of first Campylobacterinfections was 9 per 100 person years, of first Salmonellainfections 4 per 100 person years. For 22% of the episodes of gastroenteritis, a general practitioner was consulted (either by phone or by practice visit). For 52% of the episodes, medicine were used. For 34% of the episodes, absence from school was reported and for 15%, absence from work was reported. Despite of possible biases, we can conclude that the incidence of gastroenteritis is very high and causes considerable use of medication, consultation of general practitioners and absence from work and school.
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  • 6
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Smooth pursuit eye movements are evoked by retinal image motion of visible moving objects and can also be driven by the internal representation of a target due to extraretinal mechanisms (e.g. efference copy). To delineate the corresponding neuronal correlates, functional magnetic resonance imaging at 1.5 T was applied during smooth pursuit at 10 °/s with continuous target presentation and target blanking for 1 s to 16 right-handed healthy males. Eye movements were assessed during scanning sessions by infra-red reflection oculography. Smooth pursuit performance was optimal when the target was visible but decreased to a residual velocity of about 30% of the velocity observed during continuous target presentation. Random effects analysis of the imaging data yielded an activation pattern for smooth pursuit in the absence of a visual target (in contrast to continuous target presentation) which included a number of cortical areas in which extraretinal information is available such as the frontal eye field, the superior parietal lobe, the anterior and the posterior intraparietal sulcus and the premotor cortex, and also the supplementary and the presupplementary eye field, the supramarginal gyrus, the dorsolateral prefrontal cortex, cerebellar areas and the basal ganglia. We suggest that cortical mechanisms such as prediction, visuo-spatial attention and transformation, multimodal visuomotor control and working memory are of special importance for maintaining smooth pursuit eye movements in the absence of a visible target.
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  • 7
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Beckenbodenschwäche ; Stuhlentleerungsstörungen ; Organvorfall am Becken ; Magnetresonanztomographie ; Organbeweglichkeit im Bild ; Key words Pelvic floor descent ; Stool outlet disorder ; Pelvic Organ prolapse ; Magnetic Resonance Tomography ; Imaging of Organ mobility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose. Functional MRI of the pelvic floor allowes mapping and definition of different forms of pelvic floor dysfunction. Methods. We performed functional MRT of the pelvic floor in 39 healthy nulliparas and 324 patients. The diagnosis of a pathological organ descent was made if certain landmarks of the pelvic floor compartments descended below the pubococcygeal reference-line (PC-line). Results. If there was no organ descent below the PC-line on straining and if the pelvic floor muscles hardly changed position, a normal finding was diagnosed. 70% of organ prolapses came in the combined form. The generally gradual development of an organ descent led to a change of the main finding in 21,6%. The masking of a cystocele (48,6%) or of an enterocele (34,3%) by a rectocele was most frequent in these cases. Discussion. The use of functional MRI of the pelvic floor appears to be especially useful in young patients, in cases of divergent clinical and sonographic or radiological findings and if the presence of a predominant hernial sac with or without enterocele/rectocele is supposed.
    Notes: Zusammenfassung Ziel. Die funktionelle MRT des Beckenbodens ermöglicht die Dokumentation und Definition der verschiedenen Manifestationsformen einer Beckenbodeninsuffizienz. Methodik. Es wurde bei 39 gesunden Nulliparen und 324 Patientinnen eine funktionelle MRT des Beckenbodens durchgeführt. Ein pathologischer Organdeszensus wurde dokumentiert, wenn bestimmte Kennstrukturen der Beckenbodenkompartimente unterhalb der pubokokkygealen Referenzlinie (PC-Linie) zu liegen kamen. Ergebnisse. Beim Normalbefund zeigt sich unter Pressen kein Deszensus der Kennstrukturen unterhalb der PC-Linie und die Beckenbodenmuskulatur verändert ihre Position kaum. In 70% fand sich die kombinierte Form eines Organdeszensus. Die meist stufenweise Entwicklung eines Organvorfalles führte bei 21,6% zu einem Wechsel des Hauptbefundes. Am häufigsten war hierbei die Maskierung einer Zystozele (48,6%) oder einer Enterozele (34,3%) durch eine Rektozele. Diskussion. Der Einsatz der funktionellen MRT des Beckens erscheint insbesondere bei jungen Patientinnen gerechtfertigt, und in Fällen, in denen klinische und sonographische oder röntgenologische Befunde divergieren sowie bei einem vermuteten dominanten Brucksack mit oder ohne Peritoneozele, bzw. Enterozele.
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  • 8
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Funktionelle MRT ; MRT Beckenboden ; Beckenbodendysfunktion ; MRT Referenzwerte ; Key words Pelvic floor-MRI ; MRI-cine studies ; Pelvic Organs ; MRI-Pelvic Organs ; prolapse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose. Functional cine MRI of the pelvic floor is a yet another modality in addition to various radiological fluoroscopic techniques. This article describes our own method in view of the recent literatur and provides morphometric reference values. Material and method. We examined 20 nulliparous women (range of age: 25–51 years) with normal findings in the gynecological and urodynamic examination. Functional cine MRI was performed on a 1.5 Tesla equipment after opacification of the vagina and rectum. We used a T2-weighted gradient- echo sequence (Ture-FISP) to determine the position of the reference organs at rest and during straining/defecation. Two different reference lines were used. In addition 29 morphometric and functional parameters were measured, all of them being observer independant. Results. Functional cine MRI was able to show the extent and interaction of the pelvic floor organs in all cases with the reference organs always remaining above the pubococcygeal reference line. The depht of the rectocele was 2 cm. With the exception of the diameter of urogenital hiatus the different parts of the levator ani muscle could not be determined. Discussion. Functional cine MRI using an appropiate organ opacification and slice positioning is an objective, unifying diagnostic approach of the pelvic floor. The reference data given can be of help to distinguish normal from abnormal findings.
    Notes: Zusammenfassung Zielsetzung. Die funktionelle MRT des Beckenbodens eröffnet neue Perspektiven in der Diagnostik. In diesem Beitrag soll die eigene Methodik dargestellt und Referenzwerte bei einem Kollektiv gesunder Nulliparen ermittelt werden. Material und Methode. 20 Nulliparae (Alter 25–51 Jahre) mit unauffälligem gynäkologischen und urodynamischen Befund. Funktionelle MRT mit Kontrastierung von Scheide und Rektum an einem 1,5-Tesla-System. Mit Hilfe einer T2-gewichteten Gradientenechosequenz (True-FISP) wurden die Veränderungen der Referenzorgane in Ruhe und während des Pressvorgangs mit Defäkation anhand zweier Referenzlinien bestimmt. Weitere 29, zuvor im Interobservertest validierte, knöcherne und muskuläre Kenngrößen wurden ausgemessen. Ergebnisse. Die funktionelle MRT konnte den Umfang der Lageveränderungen der Beckenbodenorgane in allen Fällen dokumentieren. Die Beckenorgane traten in keinem Fall tiefer als die pubokokkzygeale Referenzlinie. Tiefe der physiologischen Rektozele 〈2 cm. Bei den muskulären Kenngrößen konnten mit Ausnahme der Weite des Hiatus urogenitalis keine weiteren Anteile des M. levator ani ausreichend sicher bestimmt werden. Diskussion. Die funktionellen MRT kann als modular aufgebaute Untersuchung mit variabler Organkontrastierung und angepasster Schichtführung den gesamten Beckenboden mit seinen Organen erfassen. Die an gesunden Probandinnen ermittelten Referenzwerte tragen dazu bei, pathologische Veränderungen zu identifizieren.
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