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  • 1990-1994  (2)
  • Distal shunt failure  (1)
  • Honey bee  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular life sciences 49 (1993), S. 530-532 
    ISSN: 1420-9071
    Schlagwort(e): Honey bee ; Apis mellifera ; mitochondrial DNA ; colonization ; subspecies ; population genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Since the introduction of an African subspecies into Brazil in the mid-1950's1, descendent ‘Africanized’ honey bees (Apis mellifera L.) have spread throughout the Neotropics and into temperate North America. Restriction enzyme analysis of 422 feral honey bee colonies collected from non-Africanized areas in the southern United States revealed that over 21% of them had mitochondrial DNA (mtDNA) derived from a European race established in North America by the 17th century, 77% of them had mtDNA common in honey bees maintained by beekeepers and about 1% exhibited African mtDNA. Further analysis revealed that the African mtDNA was derived from a north African subspecies imported to the US in the 19th century.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Child's nervous system 10 (1994), S. 524-528 
    ISSN: 1433-0350
    Schlagwort(e): Proximal shunt failure ; Distal shunt failure ; Time to shunt failure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Proximal obstruction is reported to be the most common cause of ventriculoperitoneal (VP) shunt failure, suggesting that imperfect ventricular catheter placement and inadequate valve mechanisms are major causes. This study retrospectively examined patterns of shunt failure in 128 consecutive patients with symptoms of shunt malfunction over a 2-year period. Factors analyzed included site of failure, time from shunt placement or last revision to failure, age of patient at time of failure, infections, and primary etiology of the hydrocephalus. One hundred of these patients required revisions; 14 revisions were due to infections. In this series there was a higher incidence of distal (43%) than of proximal (35%) failure. The difference was not statistically significant when the overall series was considered; however, when factoring time to failure as a variable, marked differences were noted regardless of the underlying cause of hydrocephalus or the age of the patient. Of the 49 patients needing a shunt revision or replacement within 2 years of the previous operation, 50% had proximal malfunction, 14% distal, and 10% had malfunctions attributable directly to the valve itself. Also, 12 of the 14 infections occurred during this time interval. In sharp contrast, of the 51 patients having shunt failure from 2 to more than 12 years after the previous procedure, 72% had distal malfunction, 21% proximal, and only 6% had a faulty valve or infection. This difference between time to failure for proximal versus distal failures was statistically significant (P〈0.00001 for both Student's t-test and non-parametric Mann-Whitney U-test). It is concluded that these data are valuable for interpreting outcome studies of novel valve systems and ventricular catheter placement techniques, by defining a time frame during which these modifications can be reliably evaluated.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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