Design and development of chiral reagents for the chromatographic e.e. determination of chiral alcohols

(S)-Trolox methyl ether is known as a powerful chiral reagent for the e.e. determination of chiral alcohols by separation of the corresponding diastereoisomeric esters on achiral GC and SFC columns. In order to further improve his methodology, five possible candidates resultings from variation of structural elements of parent reagent have been tested for derivatization with selected alcohols and subsequent analysis of the diastereoisomeric pairs of esters. The results of this optimization procedure showing the ways to new potent reagents are discussed. © 1996 Wiley-Liss, Inc.     

Attachment site of the genetic element e14.

The Escherichia coli K-12 genetic element, e14, contains a 216-base-pair region that is homologous to a portion of the host chromosome. This region serves as the integration site for the element. The 216-base-pair homology is interrupted by 28 mismatches distributed through the sequence. The actual integrative crossover occurs within the first 11 base pairs from one end of the region. To test factors which affect e14 site-specific recombination, we cloned the attachment sites of free e14 and the host chromosome into the same plasmid. The cloned attachment sites recombined intramolecularly in a process that required the presence of a chromosomal copy of e14 in the host cell as well as the induction of SOS. Recombination events that mimicked both integration and excision occurred under the same conditions and to roughly the same extent.     

Netzwerk Hypophysen- und Nebennierenerkrankungen e.V.

Patientenorganisationen - Selbsthilfegruppen

Netzwerk Hypophysen- und Nebennierenerkrankungen e.V.     

R.b.e. and o.e.r. of extended-Bragg-peak helium ions: survival and development of rat embryos.

Rats were exposed under aerobic or hypoxic conditions to 200-1200 rads of 60Co gamma-rays or extended-Bragg-peak helium ions on the eighth day of gestation. Uterine contents were examined on the twentieth day of gestation. At the 50 per cent embryonic survival level, helium ion r.b.e. was 1(.0) (aerobic) and 1(.2) (hypoxic). Maximum attainable gamma-ray and helium-ion o.e.r.s. were 2(.2) and 1(.7) respectively, indicating an oxygen-effect gain (o.e.g.) of 1(.2). At the 10 per cent survival level helium ion r.b.e. was 1(.1) (aerobic) and 1(.4) (hypoxic). Gamma-ray and helium-ion 0.e.r.s. were 2(.0) and 1(.5) respectively, indicating a helium ion o.e.g. of 1(.3). These data demonstrate that the small fraction of high-LET radiation present in this helium ion beam has a neglible effect on the aerobic r.b.e., but lowers the effective o.e.r. of the beam approximately 25 per cent relative to that of gamma-rays. Helium ions were significantly more effective than gamma-rays in killing embryos under hypoxic conditions, in producing congenital abnormalities under aerobic conditions, and in stunting foetal growth under both conditions.     

e antigen in acute hepatitis B.

To examine the association between e antigen and hepatitis-B surface antigen (HBs Ag) we studied 90 inpatients with acute viral hepatitis type B. e Antigen was present in 24 of the patients; these patients had detectable levels of HBs Ag for significantly longer than the 66 with no e antigen in their serum. The HBs Ag subtypes D (adw) and Y (ayw) were similarly distributed among patients with e antigen and among those without, and no differences in the results of biochemical liver function tests were observed between the two groups during the acute phase of illness. Three of the five patients who developed clinical and histological signs of chronic liver disease were positive for e antigen, a finding which supports the hypothesis that e antigen has a prognostic value in hepatitis B.     

Le Piante e la Musica. Riassunto

Abstract

The Plants and the Music. — The valuable contribute that the Biology may offer to the scientific study of the « essence » of the Music is pointed out. The plants as Animals and as remotest ancestors of the humanity, contribute to form what the A. calls the « Promusic », that is the natural and necessary starting-point of the evolution of the Music, which is exclusive work of the man. The Plants particularly, although indirectly, showing wonderful instances of transformations and associations of simple in complex forms, as well of colours and scents, have certainly inspired to the Man the Harmony, which is just in Music the Art, unknown to the Ancients, in associating aesthetically sounds and timbres.     

An e.p.r. study of the non-equivalence of the copper sites of caeruloplasmin.

The two Type 1 (blue) copper-binding sites of caeruloplasmin were spectroscopically differentiated by the kinetic analysis of the e.p.r. spectra during the redox cycle. One blue copper, with a hyperfine splitting constant (A parallel) of 6.8 mT, which was rapidly reduced, was not reoxidized by oxygen, whereas it was reoxidized by H2O2. The other blue copper (A parallel = 5.8 mT), which was reduced slowly, was rapidly reoxidized by either oxygen or H2O2. A conformational change of the Type 2 copper was concomitant with the fast reduction of Type 1 copper, whereas its reduction occurred during the slow phase. This sequence of events was reversed in the reoxidation step, that is, the Type 2 copper reappeared rapidly as the species with altered conformation and reverted to the symmetry typical of the native state in the slow phase. The specific reaction of a blue-copper site with the H2O2 can tentatively be related to the established ability of caeruloplasmin to prevent 'oxidative' attack of proteins and lipids.