Structural changes in the tissues of white rats after capsaicin administration

Attitudes to health and illness may differ between rural and urban dwellers. Issues that may relate to the provision of health services to rural dwellers are raised for consideration. The response of urban dwellers to illness or disability has often been linked to discomfort caused by pain or cosmetic attractiveness, while for rural dwellers the response to illness or disability is often related to the degree to which the illness or disability affects productivity. Often the rural resident will postpone seeking medical or associated services until it is economically or socially convenient. The notion of exposing their private lives to strangers or acquaintances from the local based services or to undertake the journey to distant services where the cultural or behavioural differences could be misunderstood, may impact on rural dwellers' well-being. Health service providers in rural areas need to understand such differences and difficulties when offering services.     

Comparative modeling of substrate binding in the S1' subsite of serine carboxypeptidases from yeast, wheat, and human

Human cathepsin A ("lysosomal protective protein"; E.C.3.4.16.5) is a multifunctional lysosomal protein which forms a high-molecular-weight complex with beta-galactosidase and alpha-neuraminidase, protecting them against intralysosomal proteolysis. In addition to this protective function, cathepsin A is a serine carboxypeptidase and the understanding of its catalytic function requires a definition of its substrate specificity. For this purpose, we used a combined experimental [Pshezhetsky, A. V., Vinogradova, M. V., Elsliger, M.-A., El-Zein, F., Svedas, V.K., & Potier, M. (1995) Anal. Biochem. 230, 303-307] and theoretical approach comparing cathepsin A to two different homologous carboxypeptidases of the same family: yeast carboxypeptidase Y and wheat carboxypeptidase II. We computed the energies involved in substrate binding to the S1' subsite (C-terminal) of cathepsin A using a structural model based on the X-ray structure of the homologous wheat carboxypeptidase II. The binding energies of N-blocked Phe-Xaa dipeptide substrates to the active sites of cathepsin A, wheat carboxypeptidase II, and yeast carboxypeptidase Y were estimated using a molecular mechanics force field supplemented with a solvation energy term. This theoretical analysis showed a good correlation with the experimentally determined free energies of substrate binding. This result validates the use of this approach to analyze the energetics of substrate binding to the S1' subsite and provides a rational interpretation of serine carboxypeptidase-substrate interactions in molecular terms. We conclude that the three serine carboxypeptidases have similar affinities for substrates with hydrophobic P1' amino acid residues but that the wheat enzyme has an additional capacity for binding positively charged P1' residues. Finally, the substrate specificity of human cathepsin A is very similar to that of carboxypeptidase Y, with a high binding affinity for substrates with hydrophobic P1' residues, but the affinity of cathepsin A for P1; Phe residue is higher than for the Leu residue.     

Interaction of ribosomes with membranes in vitro

Fluorescent "fusion-reporting" probe (R18) was used to study the interaction of ribosomes with membranes in vitro. The latter was incorporated both in the membranes, and ribosomes. The interaction of R18-labeled ribosomes with non-labeled liposomes (of different size and composition) or microsomes increased the fluorescence observed, i.e., the dilution of fluorescent probe took place. The dependence of interaction process on the change of liposomes indicates that the interaction between ribosomes and negatively charged liposomes was more efficient, than that with neutral ones. It is shown that ribosomes can interact with phospholipid membranes even after degradation of protein components accessible for proteins. The interaction of R18-labeled membranes with non-labeled ribosomes results in the increase of fluorescence too. Results obtained indicate to the possibility of direct interaction between ribosomes and membranes.     

The pea (Pisum sativum L.) genes sym33 and sym40 control infection thread formation and root nodule function

Two novel non-allelic mutants that were unable to fix nitrogen (Fix ) were obtained after EMS (ethyl methyl sulfonate) mutagenesis of pea (Pisum sativum L.). Both mutants, SGEFix(-)-1) and SGEFix(-)-2, form two types of nodules: SGEFix(-)-1 forms numerous white and some pink nodules, while mutant SGEFix(-)-2 forms white nodules with a dark pit at the distal end and also some pinkish nodules. Both mutations are monogenic and recessive. In both lines the manifestation of the mutant phenotype is associated with the root genotype. White nodules of SGEFix(-)-1 are characterised by hypertrophied infection threads and infection droplets, mass endocytosis of bacteria, abnormal morphological differentiation of bacteroids, and premature degradation of nodule symbiotic structures. The structure of the pink nodules of SGEFix(-)-1 does not differ from that of the parental line, SGE. White nodules of SGEFix(-)-2 are characterised by "locked" infection threads surrounded with abnormally thick plant cell walls. In these nodules there is no endocytosis of bacteria into host-cell cytoplasm. The pinkish nodules of SGEFix(-)-2 are characterised by virtually undifferentiated bacteroids and premature degradation of nodule tissues. Thus, the novel pea symbiotic genes, synm40 and sym33, identified after complementation analysis in SGEFix(-)-1 and SGEFix(-)-2 lines, respectively, control early nodule developmental stages connected with infection thread formation and function.     

Plasticity of hippocampal corticosteroid receptors during aging in the rat

OBJECTIVE: The purpose of this study was to describe and validate an image-quality phantom to be used in dental radiography for comparison of film and digitally acquired images. STUDY DESIGN: An aluminum block of 12 steps, with 7 holes in each step, was covered by acrylic blocks. This phantom was radiographed with Kodak Ultra-speed and Ektaspeed Plus films at 70, 65, and 60 kVp with the whole exposure range available. All together, 50 dental films were randomly sequenced and presented to 7 observers. The average number of perceptible holes from all steps was plotted against exposure for each tube voltage and film type, generating a modified perceptibility curve. The tentative optimum exposure level was determined from perceptibility curves in each experimental condition and compared with that determined by means of the standard aluminum stepwedge and the preset time of the x-ray machine. The density range of this phantom at the optimum exposure was compared with that of clinical dental radiographs. Validity of the phantom was evaluated according to the optimum exposure level from the modified perceptibility curves and the overall density range. Finally, the average maximum numbers of perceptible holes at the tentative optimum exposure level were compared for each tube voltage and film type. The statistical test used was a 2-way factorial analysis of variance. RESULTS: The exposure at the perceptibility curve peak approximated that obtained by means of the standard aluminum step-wedge and the time preset by the manufacturer. The overall density range at the perceptibility curve peak covered the clinical density range for each tube voltage and film type. There were no statistically significant differences between film types or among tube voltages. CONCLUSIONS: The x-ray attenuation range for this phantom seemed to approximate clinical conditions. In addition, differences in image quality could be quantitatively evaluated by means of the number of the holes seen in the phantom.