Ultrastructural and ultracytochemical changes in the lungs of rats with diabetes mellitus

Diabetes mellitus was produced in Rats by means of a single streptozotocin injection. The evolution of the lung ultrastructure and of the state of the alveolar epithelium glycocalix was followed during two months. Among the different cellular types of the lung parenchyma, the main alterations were revealed in the pneumocytes of type II. They consisted in severe enlargement of the endoplasmatic rough net channels, diminution of the quantity of the lamellated corpuscles and delay of their output out of the cytoplasm, the reduction of microvilli and thinning of the glycocalix. As an answer to the epithelium alteration, a regeneration of the type II pneumocytes was discovered. A structural insufficiency of the phagocyte system--polymorph nuclear leucocytes and alveolar macrophages was noted.     

Surgical Stress Delays Prostate Involution in Mice

Androgens control growth of prostate epithelial cells and androgen deprivation induces apoptosis, leading to prostate involution. We investigated the effects of surgical stress on prostate involution induced by androgen ablation and determined the underlying mechanisms. Androgen ablation in mice was induced by surgical castration and administration of the anti-androgenic drugs bicalutamide and MDV3100. Surgical stress was induced by sham castration under isoflurane anesthesia. Surgical stress delayed apoptosis and prostate involution induced by anti-androgenic drugs. These effects of stress were prevented by administering the selective beta2-adrenoreceptor antagonist ICI118,551 and were also blocked in BAD^3SA/WT mice expressing phosphorylation-deficient mutant BAD3SA. These results indicate that apoptosis and prostate involution in response to androgen ablation therapy could be delayed by surgical stress via the beta2-adrenoreceptor/BAD signaling pathway. Thus, surgery could interfere with androgen ablation therapy, whereas administration of beta2-adrenoreceptor antagonists may enhance its efficacy.     

Postsynaptic GABABRs Inhibit L-Type Calcium Channels and Abolish Long-Term Potentiation in Hippocampal Somatostatin Interneurons

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Replication slippage may cause parallel evolution in the secondary structures of mitochondrial transfer RNAs

Presence of the dihydrouridine (D) stem in the mitochondrial cysteine tRNA is unusually variable among lepidosaurian reptiles. Phylogenetic and comparative analyses of cysteine tRNA gene sequences identify eight parallel losses of the D-stem, resulting in D-arm replacement loops. Sampling within the monophyletic Acrodonta provides no evidence for reversal. Slipped-strand mispairing of noncontiguous repeated sequences during replication or direct replication slippage can explain repeats observed within cysteine tRNAs that contain a D-arm replacement loop. These two mechanisms involving replication slippage can account for the loss of the cysteine tRNA D-stem in several lepidosaurian lineages, and may represent general mechanisms by which the secondary structures of mitochondrial tRNAs are altered.      

Synthesis and characterization of allosteric probes of substrate channeling in the tryptophan synthase bienzyme complex

Allosteric interactions regulate substrate channeling in Salmonella typhimurium tryptophan synthase. The channeling of indole between the alpha- and beta-sites via the interconnecting 25 A tunnel is regulated by allosteric signaling arising from binding of ligand to the alpha-site, and covalent reaction of l-Ser at the beta-site. This signaling switches the alpha- and beta-subunits between open conformations of low activity and closed conformations of high activity. Our objective is to synthesize and characterize new classes of alpha-site ligands (ASLs) that mimic the binding of substrates, 3-indole-d-glycerol 3'-phosphate (IGP) or d-glyceraldehyde 3-phosphate (G3P), for use in the investigation of alpha-site-beta-site interactions. The new synthesized IGP analogues contain an aryl group linked to an O-phosphoethanolamine moiety through amide, sulfonamide, or thiourea groups. The G3P analogue, thiophosphoglycolohydroxamate, contains a hydroxamic acid group linked to a thiophosphate moiety. Crystal structures of the internal aldimine complexed with G3P and with three of the new ASLs are presented. These structural and solution studies of the ASL complexes with the internal aldimine form of the enzyme establish the following. (1) ASL binding occurs with high specificity and relatively high affinities at the alpha-site. (2) Binding of the new ASLs slows the entry of indole analogues into the beta-site by blocking the tunnel opening at the alpha-site. (3) ASL binding stabilizes the closed conformations of the beta-subunit for the alpha-aminoacrylate and quinonoid forms of the enzyme. (4) The new ASLs exhibit allosteric properties that parallel the behaviors of IGP and G3P.     

Usefulness of real-time PCR in long-term follow-up of follicular lymphoma patients

The aim of this study was to evaluate the usefulness of quantitative real-time PCR (RQ-PCR) for the monitoring of molecular remission in follicular lymphoma (FL) patients during long-term follow-up. RQ-PCR by the use of TaqMan detection system is a sensitive tool to monitor minimal residual disease (MRD) in FL through amplification of the t(14;18) fusion gene during and post-therapy. In most cases the breakpoint region occurs within the major breakpoint region (MBR). Among 75 patients diagnosed with FL, cells harboring the fusion gene BCL2/JH were found in peripheral blood of 31 patients (41%). We further monitored 30 of these patients in a period varying from 6 months to 5 years by RQ-PCR. In our study the level indicating the possibility of the presence of MRD was established at more than five t(14;18)-positive cells in the background of 83,000 normal cells. The results of this work also confirmed that the presence of MRD detected by RQ-PCR is an indication for careful observation of patients because of a higher risk of disease recurrence.     

Focusing the view on nature's water-splitting catalyst

Nature invented a catalyst about 3Gyr ago, which splits water with high efficiency into molecular oxygen and hydrogen equivalents (protons and electrons). This reaction is energetically driven by sunlight and the active centre contains relatively cheap and abundant metals: manganese and calcium. This biological system therefore forms the paradigm for all man-made attempts for direct solar fuel production, and several studies are underway to determine the electronic and geometric structures of this catalyst. In this report we briefly summarize the problems and the current status of these efforts and propose a density functional theory-based strategy for obtaining a reliable high-resolution structure of this unique catalyst that includes both the inorganic core and the first ligand sphere.     

Synthetic substrates as amine donors and acceptors in microbial transglutaminase-catalysed reactions

Microbial transglutaminase (EC 2.3.2.13) (mTGase) catalyses a calcium-independent acyl-transfer reaction in which -(γ-glutamyl)lysine bonds are formed using the γ-carboxyamide groups of peptide-bound glutamine residues and the amino group of lysine side-chains. Here we present a comparative study on alternative lysine and glutamine substitutes in mTGase catalysis. A homologous series of ω-amino acids, serving as lysine substitutes, was incorporated into carbobenzoxy-l-glutaminylglycine (CBZ-Gln-Gly). The rate constants and particular conversion rates increased with increasing chain length. As for the glutamine substitutes, adipic diamide, glutaric monoamide, and glutaric diamide were converted with monodansylcadaverine (DNS-cadaverine) under mTGase catalysis. For the synthetic glutamine substitutes, the substrates of natural chain length, glutaric mono- and diamide, are better converted than the longer adipic diamide indicating that the window of opportunity seems to be smaller. Synthetic substrates, serving as amine acceptors, offer new opportunities in the field of transglutaminase-catalysed reactions.