Biomedical subjects

A Schimanski

Publications and source records attributed to A Schimanski.

3 recordsLinked to original sources

PubMed2001

Thymine-metal ion interactions: relevance for thymine quartet structures.

Apart from their function as counter ions for the charge neutralization of nucleic acids, alkali metal ions play important roles in stabilizing particular multistranded nucleic acids, e.g. guanine quartets in telomeres and uracil (U) or thymine (T) quartets. Here X-ray crystal structure determinations of a series of alkali metal ions (Na+, K+, Rb+, Cs+) as well as of Mg2+ and H5O2+ adducts with the model bases 1-methylthymine and 1-ethylthymine are reported, which bear relevance to the question of thymine quartet (T4) geometries. The compounds isolated differ in their stoichiometries (T:M = 4:1, 2:1, 1:1), and the ways the metal ions interact with the bases. The two extremes are exclusive metal coordination to exocyclic oxygen atoms of the T bases and exclusive H bonding between M aqua cations and the bases.

Binding Sites↗

PubMed1999

Liposomal amphotericin B (AmBisome) application and hepatic microsomal enzyme function in the rat.

In the present study we investigated the influence of AmBisome, a lyophilized liposomal amphotericin B formulation on various hepatic cytochrome P450-dependent mixed function oxidases, antipyrine clearance and hepatic glucose-6-phosphatase activity in rats. Animals were treated intravenously for 6 days with AmBisome (15 mg kg-1 body weight). Subsequently, the enzyme activities and cytochrome P450 concentrations were measured ex vivo in hepatic microsomes. Following AmBisome the activity of the microsomal ethoxycoumarin-O-deethylase increased significantly from 333 +/- 77 pmol mg-1 to 459 +/- 125 pmol mg-1, whereas benzpyrenhydroxylase and glucose-6-phosphatase did not change compared with the controls. Accordingly, antipyrine clearance was not affected by AmBisome treatment. Microsomal cytochrome P450 concentrations as well as total microsomal protein concentrations were not changed following treatment with AmBisome and it did not affect either serum levels of liver transaminases or bilirubin. The results show that the application of a high AmBisome dose had no adverse effects on a variety of microsomal hepatic enzymes and the antipyrine clearance in rats. Thus, it seems likely that AmBisome does not seriously impair metabolic liver function.

Amphotericin B↗

PubMed1999

5,5'-Diuracilyl Species from Uracil and

Not only UV radiation can bring about the dimerization of the pyrimidine nucleobase uracil, a metal ion can as well! The reaction proceeds by a reductive elimination process of two cis-oriented uracil entities, each bonded to Au(III) through C5 [Eq. (a)]. R/R'=H/CH(3), CH(3)/CH(3), H,C(5)H(9)O(4)

Journal Article↗