The large ribosomal subunit catalyzes peptide bond formation and will do so by using small aminoacyl-and peptidyl-RNA fragments of tRNA. We have refined at 3-Å resolution the structures of both A and P site substrate and product analogues, as well as an intermediate analogue, bound to the Haloarcula marismortui 50S ribosomal subunit. A P site substrate, CCA-Phe-caproic acid-biotin, binds equally to both sites, but in the presence of sparsomycin binds only to the P site. The CCA portions of these analogues are bound identically by either the A or P loop of the 23S rRNA. Combining the separate P and A site substrate complexes into one model reveals interactions that may occur when both are present simultaneously. The ␣-NH2 group of an aminoacylated fragment in the A site forms one hydrogen bond with the N3 of A2486 (2451) and may form a second hydrogen bond either with the 2 OH of the A-76 ribose in the P site or with the 2 OH of A2486 (2451). These interactions position the ␣ amino group adjacent to the carbonyl carbon of esterified P site substrate in an orientation suitable for a nucleophilic attack.

This paper describes the design of a novel ultrasonic therapy system dedicated to the breast cancer treatment and the theoretical investigation of the heating characteristics of the system. The applicator is a cylinder comprised of a stack of rings. Each ring has up to 48 transducers mounted on the inside of the ring and directed towards the centre. The transducers operate in one of two frequency bands (1.8-2.8 MHz and 4.3-40.8 MHz), arranged alternately in each ring. During treatment the patient is positioned in prone position, with the breast immersed in water and surrounded by this array. This design was modelled and optimized by 3-D simulations for a variety of treatment conditions. The simulated results demonstrate that the system has an excellent capability to achieve and maintain a temperature distribution (41.5-44 degrees C) in a quadrant to a whole breast. Initial experiments using a single ring of transducers has been performed to verify the power deposition calculation.

Bax translocation from the cytosol to mitochondria culminates a key step by which this protein mediates cell death. Here, we identified two amino acids, L70 and D71, within the BH3 domain of Bax that play a critical role in regulating Bax's cytosolic vs mitochondrial distribution. Individual substitution of these amino acids with alanine resulted in Bax conformational change, oligomerization, localization to mitochondria and cell death. Further mutational analysis indicated that L70 interacts with T174, V177 and A178 of Bax's C-terminal hydrophobic segment, while the negative charge of D71 is required for maintaining Bax in its soluble monomeric state. In summary, we have identified a new regulatory site that controls Bax's subcellular distribution and activation.

The authors point out the importance of cytological examination from the early detection point of view of the bronchiogenic carcinoma. In table 1 false positive results in non malignant lung diseases in different periods of time are indicated. In table 2 cytological results are confronted with histological types of 250 cases of bronchiogenic carcinoma. In table 3 cytological results in resectable and unresectable cases of bronchogenic carcinoma are examinated. In table 4 the percentage of positive and negative results of cytological examination upon verified cases of bronchiogenic carcinoma is presented and the necessity to carry out five or more examinations is emphasised. In table 5 and fig. 1 the percentage of positive results by an increasing number of cytological examinations even on ideal conditions is shown. Negative results do not exclude the cancer (4).

Familial porphyria cutanea tarda (PCT) results from a deficiency of uroporphyrinogen decarboxylase (URO-D) activity. Hybridization analysis of genomic DNA from unrelated normal individuals and PCT pedigree members failed to detect any major deletions, rearrangements or restriction fragment length polymorphisms at the URO-D locus.