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  • 1
    ISSN: 1432-1459
    Schlagwort(e): Alzheimer's disease ; Apolipoprotein E ; Age at onset ; Relative risk
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effect of the apolipoprotein E (apoE) genotype on the age at onset of Alzheimer's disease (AD) and the relative risk conferred by the apoE ε4 allele were studied in 91 patients and 69 healthy age-matched controls. According to the age of presentation, which varied from 44 to 95 years, subjects were divided into four groups. The inheritance of at least one ɛ4 allele was associated with a significant reduction of the age at onset by 7.7 years among patients who were 83 years or older when examined. A weaker inverse relationship between the ɛ4 allele and the age at onset was also observed among patients who were aged 44–63 years at presentation. The effect of the c4 allele was minimal or absent in the two intermediate age categories. The relative risk of AD conferred by the inheritance of at least one £4 allele showed no consistent age-related pattern. The overall risk expressed as an odds ratio was 5.0 (95% CI 2.4–10.5). With respect to the limitations of the study, we tentatively conclude (1) that the effect of the apoE ɛ4 allele on the age at onset is not restricted to AD patients of a particular age, in accordance with current hypotheses on the role of apoE gene products in the biology of AD; (2) that the relative risk of AD associated with the ɛ4 allele is not significantly modulated by age. Although the apoE ɛ4 allele is an important susceptibility factor for AD occurring in middle age as well as in later life, it is of limited value in routine clinical diagnosis and should not be used for predictive testing in asymptomatic individuals.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 25 (1999), S. 935-941 
    ISSN: 1573-1561
    Schlagwort(e): Antifungal ; diketopiperazine ; Cyphomyrmex minutus ; fungus-growing ant ; symbiosis ; Tyridiomyces formicarum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The attine fungus Tyridiomyces formicarum, the symbiont of the fungus-growing ant Cyphomyrmex minutus, produces several antifungal diketopiperazines. This represents the first identification of antifungal compounds from an attine symbiont and contradicts previous suggestions that attine fungi do not produce metabolites with antifungal activity. T. formicarum probably produces antifungal compounds in defense (1) against other fungi that invade the gardens and escape the weeding activity of the ants, or (2) against ant-pathogenic fungi that could harm the host ants. Fungi cultivated by fungus-growing ants may represent a rich source of additional bioactive metabolites.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 957-961 
    ISSN: 0044-2313
    Schlagwort(e): Cyclic thiophosphate ; cyclic thiochlorosilicate ; dichlorodithiophosphate ; dibromodithiophosphate ; crystal structures ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Two New Cyclic Thioanions: (PPh4)2[1,3-P2S8] and (PPh4)2[Si2S6Cl2]. New Synthetic Access Routes to PPh4[PS2Cl2] and PPh4[ PS2Br2](PPh4)2[P2S8] was obtained from tetraphenylphosphonium polysulfide and white phosphorus in acetonitrile. According to its X-ray crystal structure analysis (4229 reflexions, R = 0.079) the P2S82- ion consists of a six-membered ring in chair conformation made up from four sulfur and two phosphorus atoms in 1,3 positions; in addition, each P atom has two terminal sulfur atoms. (PPh4)2[Si2S6Cl2] · 2 CH2Cl2 was obtained from Na2S4, PPh4Cl and SiCl4 in dichloromethane. The Si2S6Cl22- ion also has a six-membered ring structure, consisting of four sulfur and two silicon atoms in 1,4 positions (X-ray structure analysis, 2694 reflexions, R = 0.032). PPh4[PS2Cl2] is accessible by the following reactions: 1P4S3 + PPh4Cl + chlorine in CH2Cl2;2PSCl3 + Na2S4 + PPh4Cl in CH2Cl2;3PCl5 + Na2S4 + PPh4Cl in acetonitrile;4PCl3 + Na2S4 + PPh4Cl in acetonitrile;5P4S10 + Na2S4 + PPh4Cl in acetonitrile .P4S3 or react with PPh4Cl and bromine to yield PPh4[PS2Br2]. PPh4[PS2Cl2] crystallizes isotypic to PPh4[PS2Br2] in the BiPh4[ClO4] structure type with orientational disorder of the PS2Cl2- ions in positions with site symmetry 4.
    Notizen: Aus Tetraphenylphosphonium-polysulfid und weißem Phosphor wurde in Acetonitril (PPh4)2[1,3-P2S8] hergestellt. Nach seiner Kristallstrukturanalyse mittels Röntgenbeugung (R = 7,9% für 4229 Reflexe) besteht das 1,3-P2S82--Ion aus einem sechsgliedrigen Ringgerüst in Sesselkonformation mit vier Schwefel- und zwei Phosphoratomen in 1,3-Stellung sowie zwei terminalen Schwefelatomen an den P-Atomen. (PPh4)2[Si2S6Cl2] · 2 CH2CI2 wurde aus Na2S4, PPh4Cl und SiCl4 in Dichlormethan erhalten. Das Si2S6Cl22--Ion hat ebenfalls ein sechsgliedriges Ringgerüst in Sesselkonformation, bestehend aus vier Schwefel- und zwei Si-Atomen in 1,4-Stellung (Röntgenstrukturanalyse mit 2694 Reflexen, R = 3,2%). Mit folgenden fünf Syntheseverfahren läßt sich PPh4[PS2Cl2] herstellen: 1P4S3 + PPh4Cl + Chlor in CH2Cl2;2PSCl3 + Na2S4 + PPh4Cl in CH2Cl2;3PCl5 + Na2S4 + PPh4Cl in Acetonitril4PCl3 + Na2S4 + PPh4Cl in Acetonitril5P4S10 + Na2S4 + PPh4Cl in Acetonitril.Aus P4S3 oder P4S10, PPh4Cl und Brom ist PPh4[PS2Br2] zugänglich. PPh4[PS2Cl2] kristallisiert isotyp zu PPh4[PS2Br2] im BiPh4[ClO4]-Typ, mit fehlgeordneten PS2Cl2--Ionen in Punktlagen der Symmetrie 4.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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