Abstract Aus dem Trimethylcyclohexenolaoetat (I) erhält man mit 3,4‐Bis‐chlormethyl‐furan (II) in Gegenwart von Methyllithium das Kondensat (III), das mit Lithiumalanat zu (IVa) reduziert und zu (IVb) mesyliert wird.
The cross section of the 115 In(n,γ) 116m In reaction at an incident neutron energy of 15 MeV has been determined by measuring the γ-rays following the decay of the metastable ( T 1/2 =54 min) first excited state of 116 In. By systematically varying the geometrical arrangement the corrections due to secondary low-energy neutrons could be determined. Numerical estimates of the multiple reaction corrections have been made and a comparison with the experimental results indicates a good agreement. The corrected activation capture cross section at 15 MeV is 0.7±0.3 mb which is an order of magnitude lower than previous activation measurements on the same reaction.
Specific hydroxy groups of the terminal disaccharide unit of globotriaosyl ceramide (Gb3Cer) were identified from binding studies with deoxyGb3Cer and verotoxins (VTs) [Nyholm, Magnusson, Zheng, Norel, Binnington-Boyd and Lingwood (1996) Chem. Biol. 3, 263—275]. Four such hydroxy groups (2′′, 4′′, 6′′ and 6′) were each substituted with an amino group and the corresponding deoxyamino globotrioses were conjugated to a ceramide-like aglycone which contained an adamantyl group instead of an acyl chain. Such aglycone modification significantly enhanced the water-solubility of the glycoconjugates [Mylvaganam and Lingwood (1999) Biochem. Biophys. Res. Commun. 257, 391—394]. The inhibitory potential of these soluble aminodeoxy conjugates on the binding of VT1 to Gb3Cer immobilized on an ELISA plate was evaluated. Only the 2′′ and the 6′ deoxyamino conjugates were effective inhibitors (IC50 10μM); the 4′′ and 6′′ conjugates were ineffective up to 10mM. To evaluate the importance of incorporating a rigid adamantyl hydrocarbon group into the ceramide aglycone, globotriaose was conjugated to a t-butylacetamido or an adamantaneacetamido aglycone. By similar ELISAs, only the adamantaneacetamido conjugate inhibited the binding of VT1 to Gb3Cer. When deoxyamino conjugates were adsorbed to silica on TLC plates, only the 2′′ and 6′′ conjugates bound VT1 and VT2. By a similar TLC assay, acetamido derivatives of 2′′ and 6′ deoxyamino conjugates showed less binding to VT1 and VT2. Neither the crystallographically determined structure of the VT1—globotriaose complex nor modelling studies fully explain the binding patterns shown by these deoxyamino glycoconjugates. Enhanced solvation of the ammonium group of the deoxyamino conjugate could enforce greater constraints in the binding interactions.
Abstract Spontaneous pituitary neoplasms of 19 old Sprague-Dawley rats were examined by electron microscopy. The ultrastructure suggested that the chromophobe adenomata were derived mainly from mammotropic cells and that they were functionally active. They were similar to the hyperplastic cells of the pituitary of rats given repeated injections of oestrogen.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
'/%3e%3cuse xlink:href='%23a' transform='translate(288.889 -214.211)'/%3e%3cuse xlink:href='%23a' transform='translate(108 342.749)'/%3e%3cuse xlink:href='%23a' transform='translate(469.189 342.749)'/%3e%3c/svg%3e)