Biomedical subjects

S Huss

Publications and source records attributed to S Huss.

3 recordsLinked to original sources

PubMed1991

Modular integrated fluidized bed bioreactor technology.

We describe the design and demonstrate the application of a modular integrated fluidized bed bioreactor system. Basically the system is a reactor vessel equipped with an extending cylinder and a liquid distributor plate. Instead of an external recirculation loop, as used in existing fluidized bed systems, a low shear stress impeller is used as the recirculation pump. The system has several unique features, such as modular exchangeable elements, efficient oxygenation and the option of operating as a stirred tank-, a packed bed- or a fluidized bed reactor. An example of a fluidized bed run using CHO-K1 cells is shown. Under standard culture conditions a 100-fold increase in cell density (up to 1.2 x 10(8) cells/ml) was achieved.

Animals↗

PubMed1987

Degradation by the 2',5'-phosphodiesterase activity of mouse cells requires the presence of a ribo hydroxyl group in the penultimate position of the oligonucleotide substrate.

A series of 9-beta-D-xylofuranosyladenine (xyloA or xyloadenosine) substituted analogs of 2-5A core trimer and tetramer were examined for their ability to be degraded by the 2',5'-phosphodiesterase activity of cytoplasmic extracts of mouse L cells. Two distinct groups of xyloA-substituted analogs could be readily discriminated. The first group contained xyloadenosine at the 2'-termini and included A2'p5'A2'p5'(xyloA) and A2'p5'A2'p5'A2'p5'(xyloA). These oligomers behaved as did their parent oligoadenylates in that they were equally sensitive to degradation by the 2',5'-phosphodiesterase activity. The second group of oligonucleotides bore a xyloadenosine residue in the penultimate nucleotide residues of the oligomers and included A2'p5'(xyloA)2'p5'(xyloA), (xyloA)2'p5'(xyloA)2'p5'(xyloA), A2'p5'A2'p5'(xyloA)2'p5'(xyloA) and (xyloA)2'p5' (xyloA)2'p5'(xyloA)2'p5'(xyloA). This group was quite resistant to 2',5'-phosphodiesterase activity. In all, the findings demonstrate that the ribo configuration 3'-hydroxyl group in the penultimate nucleotide of the oligonucleotide substrate is a prerequisite for the 2',5'-phosphodiesterase activity.

Adenine Nucleotides↗

PubMed1987

Structure and conformation of the branch core triribonucleotide containing 2'-5' and 3'-5' phosphodiester linkages (A 2'p5'G 3'p5'C) i solution, essential for yeast mRNA splicing, deduced from 1H-NMR.

The non-exchangeable 1H-NMR signals of the branch core trinucleotide of the lariat branch site (A2'p5'G3'p5'C, 1) and its derivatives 2 and 3 are completely assigned using one- and two-dimensional NMR techniques including NOE, COSY, NOESY, 1H-1H INADEQUATE and 2D-J-resolved spectroscopy. From the vicinal coupling constants in the individual ribose rings, NOE data and T1 measurements, the following properties of the trimers are deduced. (i) The unique stacking behavior of the trimers is S2'N3'N, and the sugar rings exist predominantly in the N-conformation (3'-endo-2'-exo). (ii) The sugar-base orientations appear to be anti. (iii) The branched trimers exist in solution as single-stranded right-handed conformations resembling A-RNA with stacking between the adenine and guanine residues in aqueous solution at 21 degrees C and pH 7.2. (iv) The calculated values for the torsion angles epsilon t and gamma+ for the trimers are 201-203 degrees and 71-86%, respectively, while the percent beta t values are higher for the guanine (87-92%) than the cytosine residues (73-77%). The computer generated depiction of the triribonucleotide 1 is also shown. These subtle structural features may act as recognition signals for this critical lariat branch site which is essential for the second step in yeast mRNA splicing.

Carbohydrate Conformation↗