Analysis of factors correlating with medical radiological examination frequencies.

The European Commission (EC) funded project Dose Datamed 2 (DDM2) had two objectives: to collect available data on patient doses from the radiodiagnostic procedures (X-ray and nuclear medicine) in Europe, and to facilitate the implementation of the Radiation Protection 154 Guidelines (RP154). Besides the collection of frequency and dose data, two questionnaires were issued to gather information about medical radiological imaging. This article analyses a possible correlation between the collected frequency data, selected variables from the results of the detailed questionnaire and national economic data. Based on a 35 countries dataset, there is no correlation between the gross domestic product (GDP) and the total number of X-ray examinations in a country. However, there is a significant correlation (p < 0.01) between the GDP and the overall CT examination frequency. High income countries perform more CT examinations per inhabitant. That suggests that planar X-ray examinations are replaced by CT examinations.

Comparative study of biological and technological characters in three generations of silkworm Bombyx mori L. ameiotic, parthenogenetically cloned lines.

PURPOSE: Detect any deviation in biologic and technologic characters of eight ameiotic-parthenogenetically cloned lines of Bombyx mori L. from different origins from a normal sexually reproduced control line in three generations. METHODS: Comparative study of the three generations was conducted in SES, Vratza, unit of the National Center for Agrarian Sciences of Bulgaria after fixing all environmental rearing conditions. RESULTS: The ameiotic-parthen-clones displayed good parthenogenetic development, although total hatchability was significantly less than the sexually reproducing control populations. Survival rates between clones and control were not significantly different. All clones displayed significantly longer larval periods. Slight decline in second generation, and a steeper one in the third generation were observed for all eight cloned lines in cocoon weight, shell weight, and shell ratio and these differences were statistically significant. Cocoon yield was significantly lower than the control throughout the three generations. CONCLUSIONS: Our parthen-cloning method has a high rate of success in comparison to other cloning methods, the cloned progeny populations although were weaker technologically (cocoon weight, shell weight, and shell ratio), the biological characters (parthenogenetic development and survival rate) were not compromised. Further study is needed to determine the thermal needs of the cloned embryos and metabolic rate of all stages.

Isolation, crystallization, and investigation of ribosomal protein S8 complexed with specific fragments of rRNA of bacterial or archaeal origin.

The core ribosomal protein S8 binds to the central domain of 16S rRNA independently of other ribosomal proteins and is required for assembling the 30S subunit. It has been shown with E. coli ribosomes that a short rRNA fragment restricted by nucleotides 588-602 and 636-651 is sufficient for strong and specific protein S8 binding. In this work, we studied the complexes formed by ribosomal protein S8 from Thermus thermophilus and Methanococcus jannaschii with short rRNA fragments isolated from the same organisms. The dissociation constants of the complexes of protein S8 with rRNA fragments were determined. Based on the results of binding experiments, rRNA fragments of different length were designed and synthesized in preparative amounts in vitro using T7 RNA-polymerase. Stable S8-RNA complexes were crystallized. Crystals were obtained both for homologous bacterial and archaeal complexes and for hybrid complexes of archaeal protein with bacterial rRNA. Crystals of the complex of protein S8 from M. jannaschii with the 37-nucleotide rRNA fragment from the same organism suitable for X-ray analysis were obtained.

Translation termination factor aRF1 from the archaeon Methanococcus jannaschii is active with eukaryotic ribosomes.

Class-1 translation termination factors (release factors (RFs)) from Eukarya (eRF1) and Archaea (aRF1) exhibit a high degree of amino acid sequence homology and share many common motifs. In contrast to eRF1, function(s) of aRF1 have not yet been studied in vitro. Here, we describe for the first time the cloning and expression in Escherichia coli of the gene encoding the peptide chain RF from the hyperthermophilic archaeon Methanococcus jannaschii (MjaRF1). In an in vitro assay with mammalian ribosomes, MjaRF1, which was overproduced in E. coli, was active as a RF with all three termination codon-containing tetraplets, demonstrating the functional resemblance of aRF1 and eRF1. This observation confirms the earlier prediction that eRF1 and aRF1 form a common structural-functional eRF1/aRF1 protein family, originating from a common ancient ancestor.