ZapA, a possible virulence factor from Proteus mirabilis exhibits broad protease substrate specificity

The opportunistic bacterium Proteus mirabilis secretes a metalloprotease, ZapA, considered to be one of its virulence factors due to its IgA-degrading activity. However, the substrate specificity of this enzyme has not yet been fully characterized. In the present study we used fluorescent peptides derived from bioactive peptides and the oxidized ß-chain of insulin to determine the enzyme specificity. The bradykinin- and dynorphin-derived peptides were cleaved at the single bonds Phe-Ser and Phe-Leu, with catalytic efficiencies of 291 and 13 mM/s, respectively. Besides confirming already published cleavage sites, a novel cleavage site was determined for the ß-chain of insulin (Val-Asn). Both the natural and the recombinant enzyme displayed the same broad specificity, demonstrated by the presence of hydrophobic, hydrophilic, charged and uncharged amino acid residues at the scissile bonds. Native IgA, however, was resistant to hydrolysis by ZapA.

Electromagnetic form factor of the pion in the space- and time-like regions within the front-form dynamics

The pion electromagnetic form factor is calculated in the space- and time-like regions from -10 (GeV/c)2 up to 10 (GeV/c)2, within a front-form model. The dressed photon vertex where a photon decays in a quark-antiquark pair is depicted generalizing the vector meson dominance ansatz, by means of the vector meson vertex functions. An important feature of our model is the description of the on-mass-shell vertex functions in the valence sector, for the pion and the vector mesons, through the front-form wave functions obtained within a realistic quark model. The theoretical results show an excellent agreement with the data in the space-like region, while in the time-like region the description is quite encouraging. © 2003 Elsevier B.V. All rights reserved.

Toll-like receptor 2 knockdown modulates interleukin (IL)-6 and IL-8 but not stromal derived factor-1 (SDF-1/CXCL12) in human periodontal ligament and gingival fibroblasts

Background: Fibroblasts are now seen as active components of the immune response because these cells express Toll-like receptors (TLRs), recognize pathogen-associated molecular patterns, and mediate the production of cytokines and chemokines during inflammation. The innate host response to lipopolysaccharide (LPS) from Porphyromonas gingivalis is unusual inasmuch as different studies have reported that it can be an agonist for Toll-like receptor 2 (TLR2) and an antagonist or agonist for Toll-like receptor 4 (TLR4). This study investigates and compares whether signaling through TLR2 or TLR4 could affect the secretion of interleukin (IL)-6, IL-8, and stromal derived factor-1 (SDF-1/CXCL12) in both human gingival fibroblasts (HGF) and human periodontal ligament fibroblasts (HPDLF). Methods: After small interfering RNA-mediated silencing of TLR2 and TLR4, HGF and HPDLF from the same donors were stimulated with P. gingivalis LPS or with two synthetic ligands of TLR2, Pam2CSK4 and Pam3CSK4, for 6 hours. IL-6, IL-8, and CXCL12mRNA expression and protein secretion were evaluated by quantitative polymerase chain reaction and enzymelinked immunosorbent assay, respectively. Results: TLR2 mRNA expression was upregulated in HGF but not in HPDLF by all the stimuli applied. Knockdown of TLR2 decreased IL-6 and IL-8 in response to P. gingivalis LPS, or Pam2CSK4 and Pam3CSK4, in a similar manner in both fibroblasts subpopulations. Conversely, CXCL12 remained unchanged by TLR2 or TLR4 silencing. Conclusion: These results suggest that signaling through TLR2 by gingival and periodontal ligament fibroblasts can control the secretion of IL-6 and IL-8, which contribute to periodontal pathogenesis, but do not interfere with CXCL12 levels, an important chemokine in the repair process.

Tonic modulation of anxiety-like behavior by corticotropin-releasing factor (CRF) type 1 receptor (CRF1) within the medial prefrontal cortex (mPFC) in male mice: Role of protein kinase A (PKA)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of Insulin-like Growth Factor I (IGF-I) on the survival and the in vitro development of caprine preantral follicles

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Glucose,cholesterol,total proteins and insulin-like growth factor typeI values in the follicular fluid of female river buffaloes (Bubalus bubalis)

Twenty six Murrah female river buffaloes, between 45 and 70 d post-partum, empty, multiparae, with an average live weight of 675 ± 56 kg, and average body condition of 3.5 points, in a 1 to 5 scale, were used to determine the concentrations of glucose, cholesterol, total protein and insulin-like growth factor type I(IGF-I) in the follicular fluid. The fluid was collected from dominant follicles, with diameters between 8 and 12 mm, by in vivo follicular aspiration. The oestrous cycle stage was not taken into account. The wave of follicular development was synchronized six days prior to the collection. Biochemical analyses of glucose and cholesterol were performed by the enzymatic colorimetric method with the utilization of commercial kits of Glicose (GOD-PAP) and Cholesterol (CHOD-PAP) (Kovalent), respectively. For the determination of total protein, the commercial kit total Protein (Kovalent), method Biuret, was employed. Readings were carried out through absorption spectrophotometry with visible light. Through the radioimmunoanalysis (RIA) technique the concentration of IGF-I was obtained using commercial kits of IRMA IGF-I (IMMUNOTECH). Descriptive statistics was used, by applying the PROC MEANS procedure of the SAS (2009) statistical package. Glucose concentrations (4.0 ± 0.75 mmol/L) and IGF-I (340 ± 129.83 ng/mL) showed higher values in female river buffaloes and dairy cows regarding those reported in other studies. However, cholesterol levels (0.51 ± 0.12 mmol/L) and total proteins (58.4 ± 4.43 g/L) were lower. Results indicate that there is a relationship between the concentration of biochemical indicators, the nutritional aspects, the diameter of the aspired follicles and the productive period.