Conformational basis for the biological activity of TOAC-labeled angiotensin II and bradykinin: Electron paramagnetic resonance, circular dichroism, and fluorescence studies

N-Terminally and internally labeled analogues of the hormones angiotensin (AII, DRVYIHPF) and bradykinin (BK, RPPGFSPFR) were synthesized containing the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4- carboxylic acid (TOAC). TOAC replaced Asp 1 (TOAC 1-AII) and Val 3 (TOAC 3-AII) in AII and was inserted prior to Arg 1 (TOAC 0-BK) and replacing Pro 3 (TOAC 3-BK) in BK. The peptide conformational properties were examined as a function of trifluoroethanol (TFE) content and pH. Electron paramagnetic resonance spectra were sensitive to both variables and showed that internally labeled analogues yielded rotational correlation times (TC) considerably larger than N-terminally labeled ones, evincing the greater freedom of motion of the N-terminus. In TFE, τ C increased due to viscosity effects. Calculation of τ Cpeptide/τ CTOAC ratios indicated that the peptides acquired more folded conformations. Circular dichroism spectra showed that, except for TOAC 1-AII in TFE, the N-terminally labeled analogues displayed a conformational behavior similar to that of the parent peptides. In contrast, under all conditions, the TOAC 3 derivatives acquired more restricted conformations. Fluorescence spectra of All and its derivatives were especially sensitive to the ionization of Tyr 4. Fluorescence quenching by the nitroxide moiety was much more pronounced for TOAC 3-AII The conformational behavior of the TOAC derivatives bears excellent correlation with their biological activity, since, while the N-terminally labeled peptides were partially active, their internally labeled counterparts were inactive [Nakaie, C. R., et al., Peptides 2002, 23, 65-70]. The data demonstrate that insertion of TOAC in the middle of the peptide chain induces conformational restrictions that lead to loss of backbone flexibility, not allowing the peptides to acquire their receptor-bound conformation. © 2004 Wiley Periodicals, Inc.

Use of the internal standardization for difficult sampling by graphite furnace atomic absorption spectrometry

This work shows the potentiality of As as internal standard to compensate errors from sampling of sparkling drinking water samples in the determination of selenium by graphite furnace atomic absorption spectrometry. The mixture Pd(NO 3) 2/Mg(NO 3) 2 was used as chemical modifier. All samples and reference solutions were automatically spiked with 500 μg l -1 As and 0.2% (v/v) HNO 3 by the autosampler, eliminating the need for manual dilutions. For 10 μl dispensed sample into the graphite tube, a good correlation (r=0.9996) was obtained between the ratio of analyte absorbance by the internal standard absorbance and the analyte concentrations. The relative standard deviations (R.S.D.) of measurements varied from 0.05 to 2% and from 1.9 to 5% (n=12) with and without internal standardization, respectively. The limit of detection (LD) based on integrated absorbance was 3.0 μg l -1 Se. Recoveries in the 94-109% range for Se spiked samples were obtained. Internal standardization (IS) improved the repeatability of measurements and increased the lifetime of the graphite tube in ca. 15%. © 2004 Elsevier B.V. All rights reserved.

Effect of microwave treatments on dimensional accuracy of maxillary acrylic resin denture base

Microwave energy has been used as an alternative method for disinfection and sterilization of dental prostheses. This study evaluated the influence of microwave treatment on dimensional accuracy along the posterior palatal border of maxillary acrylic resin denture bases processed by water-bath curing. Thirty maxillary acrylic bases (3-mm-thick) were made on cast models with Clássico acrylic resin using routine technique. After polymerization and cooling, the sets were deflasked and the bases were stored in water for 30 days. Thereafter, the specimens were assigned to 3 groups (n=10), as follows: group I (control) was not submitted to any disinfection cycle; group II was submitted to microwave disinfection for 3 min at 500 W; and in group III microwaving was done for 10 min at 604 W. The acrylic bases were fixed on their respective casts with instant adhesive (Super Bonder®) and the base/cast sets were sectioned transversally in the posterior palatal zone. The existence of gaps between the casts and acrylic bases was assessed using a profile projector at 5 points. No statistically significant differences were observed between the control group and group II. However, group III differed statistically from the others (p<0.05). Treatment in microwave oven at 604 W for 10 min produced the greatest discrepancies in the adaptation of maxillary acrylic resin denture bases to the stone casts.

Inhibitory activity of glass-ionomer cements on cariogenic bacteria

This study evaluated the antibacterial activity of the glass-ionomer cements Vitrebond (3M ESPE), Ketac Molar (3M ESPE) and Fuji IX (GC America) against S mutans, S sobrinus, L acidophilus and A viscosus, using the agar diffusion test. Inocula were obtained by the seed of indicators cultures in BHI broth incubated at 37°C for 24 hours. Base layers containing 15 mL of BHI agar and 300 μL of each bacteria suspension were prepared in Petri dishes. Six wells measuring 4 mm in diameter were made in each plate and completely filled with one of the testing materials. A 0.2% chlorhexidine solution applied in round filter papers was used as control. Tests were performed 12 times for each material and bacteria strain. After incubation of the plates at 37°C for 24 hours, the zones of bacterial growth inhibition around the wells were measured. Overall, the results showed the following sequence of antibacterial activity: Vitrebond (despite the activation mode) > 0.2% chlorhexidine > Ketac Molar > Fuji IX, according to Kruskal-Wallis and Mann-Whitney statistical tests. This study confirmed significant antibacterial activity for two conventional glass-ionomers and one resin-modified glass-ionomer material. The resin-modified glass-ionomer cement Vitrebond, regardless of the activation mode, presented the best antibacterial activity against S mutans and S sobrinus. The antibacterial activity against A viscosus for Vitrebond was similar to 0.2% chlorhexidine, while light activation reduced its antibacterial activity against L acidophilus. ©Operative Dentistry, 2005.

Advances in prodrug design

The background of prodrug design is presented herein as the basis for introducing new and advanced latent systems, taking into account mainly the versatility of polymers and other macromolecules as carriers. PDEPT (Polymer-Directed Enzyme Prodrug Therapy); PELT (Polymer-Enzyme Liposome Therapy); CDS (Chemical Delivery System); ADEPT(Antibody-Directed Enzyme Prodrug Therapy); GDEPT/VDEPT (Gene-Directed Enzyme Prodrug Therapy/Virus-Directed Enzyme Prodrug Therapy); ODDS (Osteotropic Drug Delivery System) and LEAPT (Lectin-directed enzyme-activated prodrug therapy) are briefly described and some examples are given. © 2005 Bentham Science Publishers Ltd.

Ftalato de di-(2-etilexila) (DEHP) em bolsas de PVC para soluções parenterais de grandes volumes

Large volume parenteral solutions (LVPS) are widely used as vehicles for intravenous administration of drugs and polyvinyl chloride (PVC) flexible bags are, nowadays, the plastic containers most commonly used to pack and drip-feed LVPS. An advantage of using bags is that they collapse flat and thus reduce the risk of airborne contamination and embolism caused by air in the bloodstream. They are mainly used in hospitals. This review deals with some important aspects of the PVC packaging containing the plasticizer DEHP, generally used to pack LVPS. The interaction between drug and package is discussed, with an emphasis on the migration of DEHP from the PVC bag to LVPS containing the immunosuppressant cyclosporin, and toxicological aspects are considered.

Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic: The effect of surface conditioning

This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Thirty blocks (5×5×4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR, VITA) were fabricated according to the manufacturer's instructions and duplicated in resin composite. The specimens were polished and assigned to one of the following three treatment conditions (n=10): (1) Airborne particle abrasion with 110 μm Al2O3 particles + silanization, (2) Silica coating with 110 μm SiOx particles (Rocatec Pre and Plus, 3M ESPE) + silanization, (3) Silica coating with 30 μm SiOx particles (CoJet, 3M ESPE) + silanization. The ceramic-composite blocks were cemented with the resin cement (Panavia F) and stored at 37 °C in distilled water for 7 days prior to bond tests. The blocks were cut under coolant water to produce bar specimens with a bonding area of approximately 0.6 mm2. The bond strength tests were performed in a universal testing machine (cross-head speed: 1 mm/min). The mean bond strengths of the specimens of each block were statistically analyzed using ANOVA and Tukey's test (α≤0.05). Silica coating with silanization either using 110 μm SiOx or 30 μm SiOx particles increased the bond strength of the resin cement (24.6±2.7 MPa and 26.7±2.4 MPa, respectively) to the zirconia-based ceramic significantly compared to that of airborne particle abrasion with 110-μm Al2O3 (20.5±3.8 MPa) (ANOVA, P<0.05). Conditioning the INC-ZR ceramic surfaces with silica coating and silanization using either chairside or laboratory devices provided higher bond strengths of the resin cement than with airborne particle abrasion using 110 μm Al2O3. © 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Weight loss and surface roughness of hard chairside reline resins after toothbrushing: Influence of postpolymerization treatments

Purpose: To evaluate the effect of 2 postpolymerization treatments on toothbrushing wear (weight loss) and surface roughness of 3 autopolymerized reline resins-Duraliner II (D) (Reliance Dental), Kooliner (K) (Coe Laboratories), and Tokuso Rebase Fast (T) (Tokuyama Dental)-and 1 heat-polymerized resin, Lucitone 550 (L) (Dentsply International). Materials and Methods: Specimens (40 x 10 x 2mm) of each material (n = 24) were prepared and divided into 3 groups: control (no postpolymerization treatment); water bath (immersion in water at 55°C); and microwave (microwave irradiation). Specimens were dried until constant weight was achieved and the surface roughness (Ra) was measured. Tests were performed in a toothbrush machine using 20,000 strokes of brushing at a weight of 200 g, with the specimens immersed in 1:1 dentifrice/water slurry. Specimens were reconditioned to constant weight and the weight loss (mg) and surface roughness were evaluated. Data were analyzed by 2-way analysis of variance and followed by Tukey test (α = .05). Results: In the control group, the weight loss of materials D and T was lower (P < .05) than that of L. No differences among materials were found after postpolymerization treatments (P > .05). The weight loss of material T (control = 0.5 mg) was significantly increased (P < .05) after postpolymerization treatments (water bath = 1.9 mg; microwave = 1.8 mg). For materials K and T, the toothbrushed surface roughness was higher (P < .05) after microwave and waterbath postpolymerization treatments. Material L showed increased surface roughness after microwave postpolymerization treatment. Conclusion: The toothbrushing wear resistance of L was not superior to the reline resins. The postpolymerization treatments did not improve the toothbrushing wear resistance of the materials and produced an increased surface roughness for materials L, K, and T.

Microtensile bond strength between a quartz fiber post and a resin cement: Effect of post surface conditioning

Purpose: To test the bond strength between a quartz-fiber-reinforced composite post (FRC) and a resin cement. The null hypothesis was that the bond strength can be increased by using a chairside tribochemical silica-coating system. Materials and Methods: Thirty quartz-FRCs (Light-Post) were divided into 3 groups according to the post surface treatment: G1) Conditioning with 32% phosphoric acid (1 min), applying a silane coupling agent; G2) etching with 10% hydrofluoric acid (1 min), silane application; G3) chairside tribochemical silica coating method (CoJet System): air abrasion with 30-μ SiO x-modified Al2O3 particles, silane application. Thereafter, the posts were cemented into a cylinder (5 mm diameter, 15 mm height) with a resin cement (Duo-Link). After cementation, the specimens were stored in distilled water (37°C/24 h) and sectioned along the x and y axes with a diamond wheel under cooling (Lab-cut 1010) to create nontrimmed bar specimens. Each specimen was attached with cyanoacrylate to an apparatus adapted for the microtensile test. Microtensile testing was conducted on a universal testing machine (1 mm/min). The data obtained were submitted to the one-way ANOVA and Tukey test (α = 0.05). Results: A significant influence of the conditioning methods was observed (p < 0.0001). The bond strength of G3 (15.14 ± 3.3) was significantly higher than the bond strengths of G1 (6.9 ± 2.3) and G2 (12.60 ± 2.8) (p = 0.000106 and p = 0.002631, respectively). Notwithstanding the groups, all the tested specimens showed adhesive failure between the resin cement and FRC. Conclusion: The chairside tribochemical system yielded the highest bond strength between resin cement and quartz-fiber post. The null hypothesis was accepted (p < 0.0001).

Fatigue resistance of the bond of a glass-infiltrated alumina ceramic to human dentin

Purpose: To evaluate the fatigue resistance of the bond between dentin and glass-infiltrated alumina ceramic, using different luting protocols. Materials and Methods: The null hypothesis is that the fatigue resistance varies with the luting strategy. Forty blocks of In-Ceram Alumina were prepared, and one surface of each block was abraded with 110-μm aluminum oxide particles. Then, the blocks were luted to flat dentin surfaces of 40 human third molars, using 4 different luting strategies (luting system [LS]/ceramic surface conditioning [CSC]) (n=10): (G1) [LS] RelyX-Unicem/[CSC] airborne abrasion with 110-μm Al2O3 particles; (G2) [LS] One-Step + Duo-Link (bis-GMA-based resin)/[CSC] etching with 4% hydrofluoric acid + silane agent; (G3) [LS] ED-Primer + Panavia F (MDP-based resin)/[CSC] Al2O 3; (G4) [LS] Scotchbond1+RelyX-ARC (bis-GMA-based resin)/[CSC] chairside tribochemical silica coating (air abrasion with 30-μm SiO x particles + silane). After 24 h of water storage at 37°C, the specimens were subjected to 106 fatigue cycles in shear with a sinusoidal load (0 to 21 N, 8 Hz frequency, 37°C water). A fatigue survivor score was given, considering the number of the fatigue cycles until fracture. The failure modes of failed specimens were observed in a SEM. Results: G3 (score = 5.9, 1 failure) and G4 (score = 6, no failures) were statistically similar (p = 0.33) and had significantly higher fatigue resistance than G1 (score = 3.9, 5 failures) and G2 (score = 3.7, 6 failures) (p < 0.03). SEM analysis of fractured specimens of G1 and G2 showed that almost all the failures were between ceramic and cement. Conclusion: The MDP-based resin cement + sandblasting with Al2O3 particles (G3) and bis-GMA-based resin cement + tribochemical silica coating (G4), both using the respective dentin bonding systems, were the best luting protocols for the alumina ceramic. The null hypothesis was confirmed.

Effect of dentinal surface preparation on bond strength of self-etching adhesive systems

The aim of this study was to evaluate the effects of dentin surface treatments on the tensile bond strength (TBS) of the self-etching primer Clearfil SE Bond (CSE) and the one-step self-etching One-Up Bond F (OUB). The exposed flat dentin surfaces of twenty-four sound third molars were prepared with diamond bur at high-speed, carbide bur at low-speed or wet ground with #600 grit SiC paper. The adhesive systems were applied to the dentin surfaces and light-cured according to the manufacturers' instructions. A 6-mm high composite crown was incrementally built-up and each increment was light-cured for 40 seconds. After being stored in water (37°C/24 h), the samples were serially sectioned parallel to the long axis, forming beams (n = 20) with a cross-sectional area of approximately 0.8 mm 2. The specimens were tested in a Universal Testing Machine at 0.5 mm/min. The cross-sectional area was measured and the results (MPa) were analyzed by two-way ANOVA and Tukey Test (p < 0.05). Overall, the groups treated with CSE exhibited the highest TBS for all surface treatments. Dentin surfaces prepared with carbide bur at low speed reduced TBS in the CSE group; however, OUB was not affected by surface treatments. The effect of surface abrasive methods on TBS was material-dependent.

Rendimento de óleo essencial de Salvia officinalis L. sob ação de reguladores vegetais

This study aimed to evaluate the effect of different plant growth regulators on essential oil yield in Salvia officinalis L. plants. The experiment was held in a greenhouse and the experimental design was completely randomized, with 5 treatments and three replications. The Treatments consisted in the application of gibberellic acid (GA3), benzylaminopurine (BAP), 2-chloroethyl phosphonic acid (ethephon), and Stimulate at 2%, compared with control plants (water). Applications of plant growth regulators were performed in three consecutive periods, in turn, 15, 25 and 35 days after transplanting of seeding germinating in the light at 25°C. The dry mass yield of the aerial part and the oil essential content were determined 131 days after the transplant. The aerial part of the plants was dried in an oven at 35°C; after dry mass determination, the oil was extracted by hydrodistillation and its volume was determined. Plants treated with GA 3 and Stimulate showed increase in essential oil content, while plants treated with BAP and ethephon showed decrease in essential oil volume when compared with the control plants.

Effect of curing regime on the cytotoxicity of resin-modified glass-ionomer lining cements applied to an odontoblast-cell line

Objective: The aim of this in vitro study was to evaluate the cytotoxicity of resin-modified glass-ionomer lining cements submitted to different curing regimes and applied to an immortalized odontoblast-cell line (MDPC-23). Methods: Forty round-shaped specimens of each experimental material (Fuji Lining LC and Vitrebond) were prepared. They were light-cured for the manufacturers' recommended time (MRT = 30 s), under-cured (0.5 MRT = 15 s), over-cured (1.5 MRT = 45 s) or allowed to dark cure (0 MRT). Sterilized filter papers soaked with either 5 μL of PBS or HEMA were used as negative and positive control, respectively. After placing the specimens individually in wells of 24-well dishes, odontoblast-like cells MDPC-23 (30,000 cells/cm2) were plated in each well and incubated for 72 h in a humidified incubator at 37 °C with 5% CO2 and 95% air. The cytotoxicity was evaluated by the cell metabolism (MTT assay) and cell morphology (SEM). Results: Fuji Lining LC was less cytotoxic than Vitrebond (p < 0.05) in all the experimental conditions. However, the cytotoxicity of Fuji Lining LC was noticeably increased in the absence of light-curing while the same was not observed for Vitrebond. The length of light-curing (15, 30 or 45 s) did not influence the toxicity of both lining materials when they were applied on the odontoblast-cell line MDPC-23. Significance: The light-activation plays an important role in reducing the cytotoxicity of Fuji Lining LC. Following the manufacturer' recommendation regarding the light-curing regime may prevent toxic effect to the pulp cells. © 2005 Academy of Dental Materials.

New destruxins from the marine-derived fungus Beauveria felina

Chemical investigation of the cytotoxic and anti-tuberculosis active butanone extract obtained from the growth media of the marine-derived fungus Beauveria felina led to the isolation of two new destruxins, [β-MePro] destruxin E chlorohydrin (1) and pseudodestruxin C (3), along with five known cyclic depsipeptides. The structures of the new destruxin derivatives were established by analysis of spectroscopic data, while the absolute configuration of the common amino acid residues was established by Marfey's analysis. The absolute configuration of the 2(A),4(5)-5-chloro-2,4-dihydroxypentanoic acid residue in 1 could be established by application of a J-based configuration method followed by derivatization with R-MPA-Cl and NMR analysis. © Japan Antibiotics Research Association.