Assessment of proliferating cell nuclear antigen and its relationship with proinflammatory cytokines and parameters of disease activity in multiple myeloma patients

Multiple myeloma (MM) is a malignant plasma cell disease. Several proinflammatory cytokines produced by malignant plasma cells and bone marrow (BM) stromal cells are involved in the pathogenesis of the disease. We evaluated serum levels of the proinflammatory cytokines Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), macrophage inflammatory protein-1α (MIP-1α), in MM patients before treatment, and determined its significance in tumor progression. We also analyzed the correlation between measured parameters with proliferating cell nuclear antigen (PCNA). Forty-four MM patients and 20 healthy controls were studied. Serum levels of the proinflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA), whereas PCNA value in the BM was determined by immunohistochemistry staining. The mean concentrations of the measured cytokines were significantly different among the three stages of disease, with higher values in advanced disease stage. Furthermore, patients with MM had significantly higher serum levels of the measured cytokines than in controls. A positive correlation was found between IL-6 with IL-1β, IL-8 and MIP-1α. Similarly, IL-8 and MIP-1α were positively correlated with markers of disease activity such as β2 microglobulin and LDH. The proliferation index, determined by PCNA immunostaining, was higher in advanced disease stage. Furthermore PCNA value correlated significantly with β2 microglobulin, LDH and the levels of the measured cytokines. Our results showed that the proliferative activity, as measured with PCNA, increases in parallel with disease stage. The positive correlation between PCNA and other measured mediators supports the involvement of these factors in the biology of myeloma cell growth and can be used as markers of disease activity and as possible therapeutic targets.     

Stratification,Blinding and Placebo Effect in a Randomized,Double Blind Placebo-controlled Clinical Trial of Gold Bead Implantation in Dogs with Hip Dysplasia

The purpose of this study was to investigate the need for and choice of stratification factors, and the effects of blinding and placebo in a clinical experiment. Eighty dogs with canine hip dysplasia (CHD) were included in a randomized, placebo-controlled and double blind clinical trial with stratified parallel group design, in which body weight and degree of CHD were used as stratification factors. Thirty-eight dogs were allocated to gold bead implantation and 42 to placebo. After six months, 33 of the 42 placebo-treated dogs received gold bead implantation in an open study lasting a further 18 months. The main outcome variable in the study was change in pain signs of CHD as assessed by the owner. No significant difference in the main outcome variable, regardless of the treatment given, could be detected in the two chosen stratification factors. The only factor to influence the main outcome variable significantly was age. The blinding procedure used in the study, in which 60% of the owners correctly guessed the treatment given, was found sufficient. Of those who guessed the treatment erroneously, 88% believed the treatment given was gold bead implantation. The treatment efficacy after six months in the blinded treatment group was found to be significantly larger compared to the efficacy obtained in the open study. A significant placebo effect was therefore detected. Conclusion and Clinical Relevance: The age of the dogs influenced the outcome of the CHD treatment, and is recommended as a stratification factor. A significant placebo effect has to be expected and an optimal blinding procedure is necessary in similar clinical studies.     

Common themes and variations in serine protease autotransporters

The serine protease autotransporters of the Enterobacteriaceae (SPATEs) represent a group of large-sized, multi-domain exoproteins found only in pathogenic enteric bacteria. These proteins contain a highly conserved channel-forming C-terminal domain, which functions together with YaeT/Omp85 to facilitate secretion of the passenger domain to the cell surface. The C-terminal domain also mediates autoproteolytic cleavage, which releases the passenger from the bacterial cell. The passenger folds into a characteristic parallel beta-helical stalk-like structure with an N-terminal globular domain that performs serine proteolytic activity. Here, we review and discuss recent findings that have led to a better understanding of these unique features in this virulence protein family, including their biogenesis, structural architecture, sequence variation, sub-grouping, evolution and biochemical function.     

Bacterial outer membrane proteins: topological analyses and biotechnological perspectives

The outer membrane proteins (OMPs) from gram-negative bacteria form a distinct group of integral membrane proteins with unusual primary, secondary and tertiary structures. Unlike typical prokaryotic and eukaryotic membrane proteins, bacterial OMPs contain primarily polar sequences, arranged in amphipathic antiparallel beta-barrels, and inclined to the plane of the membrane. Due to their unique structure, OMPs have recently become the subject of extensive study. This article reviews (i) experimental and theoretical approaches of topological analyses used in the study of OMPs, and (ii) the applications of OMPs.     

Cysteinyl-tRNA formation and prolyl-tRNA synthetase

Aminoacyl-tRNA (AA-tRNA) formation is a key step in protein biosynthesis. This reaction is catalyzed with remarkable accuracy by the AA-tRNA synthetases, a family of 20 evolutionarily conserved enzymes. The lack of cysteinyl-tRNA (Cys-tRNA) synthetase in some archaea gave rise to the discovery of the archaeal prolyl-tRNA (Pro-tRNA) synthetase, an enzyme capable of synthesizing Pro-tRNA and Cys-tRNA. Here we review our current knowledge of this fascinating process.     

Methanocaldococcus jannaschii prolyl-tRNA synthetase charges tRNA(Pro) with cysteine

Methanocaldococcus jannaschii prolyl-tRNA synthetase (ProRS) was previously reported to also catalyze the synthesis of cysteinyl-tRNA(Cys) (Cys-tRNA(Cys)) to make up for the absence of the canonical cysteinyl-tRNA synthetase in this organism (Stathopoulos, C., Li, T., Longman, R., Vothknecht, U. C., Becker, H., Ibba, M., and S?ll, D. (2000) Science 287, 479-482; Lipman, R. S., Sowers, K. R., and Hou, Y. M. (2000) Biochemistry 39, 7792-7798). Here we show by acid urea gel electrophoresis that pure heterologously expressed recombinant M. jannaschii ProRS misaminoacylates M. jannaschii tRNA(Pro) with cysteine. The enzyme is unable to aminoacylate purified mature M. jannaschii tRNA(Cys) with cysteine in contrast to facile aminoacylation of the same tRNA with cysteine by Methanococcus maripaludis cysteinyl-tRNA synthetase. Although M. jannaschii ProRS catalyzes the synthesis of Cys-tRNA(Pro) readily, the enzyme is unable to edit this misaminoacylated tRNA. We discuss the implications of these results on the in vivo activity of the M. jannaschii ProRS and on the nature of the enzyme involved in the synthesis of Cys-tRNA(Cys) in M. jannaschii.     

Effect of peptidyltransferase inhibitors on ribonuclease P activity from Dictyostelium discoideum – Effect of antibiotics on RNase P

The effect of several peptidyltransferase inhibitors on ribonuclease P activity from Dictyostelium discoideum was investigated. Among the inhibitors tested puromycin, amicetin and blasticidin S revealed a dose-dependent inhibition of tRNA maturation. Blasticidin S and amicetin do not compete with puromycin for the same site on the enzyme, suggesting the existence of distinct antibiotic binding sites on D. discoideum RNase P. Inhibition experiments further indicate that binding sites for blasticidin S and amicetin overlap.     

Omptin proteins: an expanding family of outer membrane proteases in Gram-negative Enterobacteriaceae

The Escherichia coli K-12 outer membrane protein OmpT is a prototype of a unique family of bacterial endopeptidases known as the omptins. This family includes OmpT and OmpP of E. coli, SopA of Shigella flexneri, PgtE of Salmonella enterica, and Pla of Yersinia pestis. Despite their sequence similarities, the omptins vary in their reported functions. The OmpT protease is characterized by narrow cleavage specificity defined by the extracellular loops of the beta-barrel protruding above the lipid bilayer. It employs a distinct proteolytic mechanism that involves a histidine and an aspartate residue. Most of the omptin proteins have been implicated in bacterial pathogenesis. As a result, the omptins are potential targets for antimicrobial drug and vaccine development. This review summarizes recent developments in omptins structure and function, emphasizes their role in pathogenesis, proposes evolutionary relation among the existing omptins, and offers possible directions for future research.     

Modulation of ribonuclease P activity by calcipotriol.

The effects of cholesterol, 7-dehydrocholesterol, vitamin D3 and several synthetic vitamin D3 analogs on ribonuclease P (RNase P) were investigated using a cell-free system from the slime mold Dictyostelium discoideum. RNase P is an ubiquitous and essential enzyme that endonucleolytically cleaves all tRNA precursors to produce the mature 5' end. Among the compounds tested, only calcipotriol was capable of affecting RNase P activity, and revealed a bimodal action at the kinetic phase of the reaction. Depending on the concentration of the drug, both activation and inhibition of tRNA maturation were observed, indicating that calcipotriol may have a direct effect on tRNA biogenesis, possibly associated with the presence of a highly reactive small ring on the side chain of its molecule.