A linear programming approach to limited angle 3D reconstruction from DSA projections.

OBJECTIVES: We investigate the feasibility of binary-valued 3D tomographic reconstruction using only a small number of projections acquired over a limited range of angles. METHODS: Regularization of this strongly ill-posed problem is achieved by (i) confining the reconstruction to binary vessel/non-vessel decisions, and (ii) by minimizing a global functional involving a smoothness prior. RESULTS: Our approach successfully reconstructs volumetric vessel structures from three projections taken within 90 degrees. The percentage of reconstructed voxels differing from ground truth is below 1%. CONCLUSION: We demonstrate that for particular applications--like Digital Subtraction Angiography--3D reconstructions are possible where conventional methods must fail, due to a severely limited imaging geometry. This could play an important role for dose reduction and 3D reconstruction using non-conventional technical setups.

Ubc8p functions in catabolite degradation of fructose-1, 6-bisphosphatase in yeast.

The key gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase) is synthesized when cells of the yeast Saccharomyces cerevisiae are grown on a non-fermentable carbon source. After shifting the cells to glucose-containing medium, in a process called catabolite degradation, FBPase is selectively and rapidly broken down. We have isolated gid mutants, which are defective in this glucose-induced degradation process. When complementing the defect in catabolite degradation of FBPase in gid3-1 mutant cells with a yeast genomic library, we identified the GID3 gene and found it to be identical to UBC8 encoding the ubiquitin-conjugating enzyme Ubc8p. The in vivo function of Ubc8p (Gid3p) has remained a mystery so far. Here we demonstrate the involvement of Ubc8p in the glucose-induced ubiquitylation of FBPase as a prerequisite for catabolite degradation of the enzyme via the proteasome. Like FBPase, Ubc8p is found in the cytoplasmic fraction of the cell. We demonstrate cytoplasmic degradation of FBPase.

[Detection of proviral HIV DNA with polymerase chain reaction in the epidermis]. / Nachweis proviraler HIV-DNA mit der Polymerasekettenreaktion in der Epidermis.

The infection of cells of the epidermis with HIV can still not be taken as proved, since the demonstration of HIV in Langerhans cells has not been universally accepted. In our study, the polymerase chain reaction was used to look for proviral HIV-DNA in epidermal cells collected by the suction blister technique. The primers flanked sequences of the gp41-encoding region of the env gene and hybridized with highly conserved HIV-DNA sequences. Amplified sequences were detected by the dot-blot technique. The PCR revealed HIV-DNA in epidermals cells of four HIV patients. In addition, HIV-DNA was detected in the mononuclear cells of the blood in the same patients by the PCR. These results strongly support the notion that in addition to blood cells, epidermal cells of HIV patients are also infected with HIV.