Validation of N-myristoyltransferase as an antimalarial drug target using an integrated chemical biology approach

Malaria is an infectious disease caused by parasites of the genus Plasmodium, which leads to approximately one million deaths per annum worldwide. Chemical validation of new antimalarial targets is urgently required in view of rising resistance to current drugs. One such putative target is the enzyme N-myristoyltransferase, which catalyses the attachment of the fatty acid myristate to protein substrates (N-myristoylation). Here, we report an integrated chemical biology approach to explore protein myristoylation in the major human parasite P. falciparum, combining chemical proteomic tools for identification of the myristoylated and glycosylphosphatidylinositol-anchored proteome with selective small-molecule N-myristoyltransferase inhibitors. We demonstrate that N-myristoyltransferase is an essential and chemically tractable target in malaria parasites both in vitro and in vivo, and show that selective inhibition of N-myristoylation leads to catastrophic and irreversible failure to assemble the inner membrane complex, a critical subcellular organelle in the parasite life cycle. Our studies provide the basis for the development of new antimalarials targeting N-myristoyltransferase

Vertebrate Vitellogenin Gene Duplication in Relation to the “3R Hypothesis”: Correlation to the Pelagic Egg and the Oceanic Radiation of Teleosts

The spiny ray-finned teleost fishes (Acanthomorpha) are the most successful group of vertebrates in terms of species diversity. Their meteoric radiation and speciation in the oceans during the late Cretaceous and Eocene epoch is unprecedented in vertebrate history, occurring in one third of the time for similar diversity to appear in the birds and mammals. The success of marine teleosts is even more remarkable considering their long freshwater ancestry, since it implies solving major physiological challenges when freely broadcasting their eggs in the hyper-osmotic conditions of seawater. Most extant marine teleosts spawn highly hydrated pelagic eggs, due to differential proteolysis of vitellogenin (Vtg)-derived yolk proteins. The maturational degradation of Vtg involves depolymerization of mainly the lipovitellin heavy chain (LvH) of one form of Vtg to generate a large pool of free amino acids (FAA 150–200 mM). This organic osmolyte pool drives hydration of the ooctye while still protected within the maternal ovary. In the present contribution, we have used Bayesian analysis to examine the evolution of vertebrate Vtg genes in relation to the “3R hypothesis” of whole genome duplication (WGD) and the functional end points of LvH degradation during oocyte maturation. We find that teleost Vtgs have experienced a post-R3 lineage-specific gene duplication to form paralogous clusters that correlate to the pelagic and benthic character of the eggs. Neo-functionalization allowed one paralogue to be proteolyzed to FAA driving hydration of the maturing oocytes, which pre-adapts them to the marine environment and causes them to float. The timing of these events matches the appearance of the Acanthomorpha in the fossil record. We discuss the significance of these adaptations in relation to ancestral physiological features, and propose that the neo-functionalization of duplicated Vtg genes was a key event in the evolution and success of the teleosts in the oceanic environment

Efficacy of conventional and experimental techniques for denture repair

This study investigated the efficacy of one experimental and three conventional techniques for denture repair. Forty maxillary dentures were constructed in dental stone casts duplicated from an edentulous copper-aluminium maxillary master cast. Two groups of 20 dentures each were prepared with Lucitone 199 (water-bath, 8 h/74 degreesC) or Acron MC (microwave, 3 min/500 W) denture base materials processed in gypsum moulds. The 40 dentures were all separated sagittally in the middle. After that, five dentures of each denture base material were repaired with one of the four following techniques: L (Lucitone 199, water-bath, 8 h/74 degreesC, gypsum mould), A (Acron MC, microwave, 3 min/500 W, gypsum mould), AR (Acron MC/R, autopolymerized, 60 psi/45 degreesC/15 min) and the experimental technique AS (Acron MC, 1 min/500 W + 1 min/0 W + 1 min/500 W, hard silicone mould). The parameters denture accuracy (DA), horizontal (HC) and vertical changes (VC) of the occlusal plane measured the efficacy of the repair techniques. The DA was determined by weighing a film of silicone impression material set in contact to the tissue surface of the denture seated on the metallic master die. For HC, cross-arch measurements were made among reference marks drilled on the teeth 11, 21, 16 and 26. The VC was obtained by calculating the relative differences in height between similar teeth of each semi-arch (pairs 13-23, 14-24, 15-25 e 16-26). For DA, HC and VC, the percentage differences between the percentage means obtained before and after repair were calculated and grouped for comparisons. Analysis of variance (SuperANOVA) and means compared by Tukey-Kramer intervals (0.05) revealed that AR repair had the best percentage difference value for DA [0.5% (P 0.05)]. For HC, there was a statistical difference (P 0.05). Denture accuracy was not affected by the interaction of base material-repair technique; repair with AR technique gave the best adaptation; the interaction of base material-repair technique did not affect HC; HC was affected by the repair technique.31111130113

Effect of cooling procedure on final denture base adaptation

Well-fitted dentures prevent hyperplasic lesions, provide chewing efficiency and promote patient's comfort. Several factors may affect final adaptation of dentures, as the type of the acrylic resin, the flask cooling procedure and the water uptake. This investigation evaluated the effect of water storage and two different cooling procedures [bench cooling (BC) for 2 h; running water (RW) at 20 degreesC for 45 min] on the final adaptation of denture bases. A heat-cured acrylic resin (CL, Classico, Classico Artigos Odontologicos) and two microwave-cured acrylic resins [Acron MC, (AC) GC Dent. Ind. Corp.; Onda Cryl (OC), Classico Artigos Odontologicos] were used to make the bases. Adaptation was assessed by measuring the weight of an intervening layer of silicone impression material between the base and the master die. Data was submitted to ANOVA and Tukey's test (0.05). The following means were found: (BC) CL=0.72 +/- 0.03 a; AC=0.70 +/- 0.03 b; OC=0.76 +/- 0.04 c//(RW) CL= 1.00 +/- 0.11 a; AC=1.00 +/- 0.12 a; OC=0.95 +/- 0.10 a. Different labels join groups that are not statistically different (P > 0.05). Comparisons are made among groups submitted to the same cooling procedure (BC or RW). The conclusions are: interaction of type of material and cooling procedure had a statistically significant effect on the final adaptation of the denture bases (P 0.05) on the final adaptation.29878779

Surface texture and some properties of acrylic resins submitted to chemical polishing

The effects of chemical polishing on dental acrylic resin properties are not well clarified. This study evaluated the effect of chemical and mechanical polishing on the residual monomer release (RM), Knoop hardness (KH), transverse strength (TS) and surface texture (ST) of a heat- and self-cured acrylic resin. Four groups were formed: GI-self-cured resin/mechanical polishing; GII-self-cured resin/chemical polishing; GIII-heat-cured resin/mechanical polishing; GIV-heat-cured resin/chemical polishing. Following the polishing procedures, specimens were stored in distilled water at 37 degreesC. The KH and RM measurements were taken after 1, 2, 8 and 32 days of storage, and TS after 2, 8 and 32 days. Surface texture was observed under SEM evaluation. Results were compared statistically at a confidence level of 95%. The following conclusions were drawn: (1) regardless of the acrylic resin and the period of analysis, chemical polishing increased RM levels, reduced KH, and did not affect TS significantly; (2) water storage increased the surface hardness of GII and GIV; (3) GII and GIV showed a smooth and wavy surface under SEM evaluation.301919

Anaerobic enhancement of protease secretion by periodontal Candida albicans strains

Session - Candida albicans: abstract no. 1728OBJECTIVES: This study evaluated the secretion patterns of aspartyl-protease (Sap) by periodontal and non-periodontal Candida albicans strains in normoxic and anoxic conditions. METHODS: Ten non-related periodontal and other ten non-periodontal C. albicans strains were planktonically grown under normoxic and anoxic conditions in protease-inducible broth. Sap activities were quantified in supernatants using azoalbumin as substrate. One unit of Sap activity was defined as the amount of enzyme necessary to increase in 0.001 unit of OD440nm per min of digestion. Protein concentrations of supernatants were spectrophotometrically determined by Coomassie blue method, with BSA as standard. The number of units of Sap activity per milligram of protein was taken as the specific enzymatic activity. RESULTS: All candidal strains, independent from their origin or atmospheric environment, secreted Saps. Non-parametric multiple comparisons among the four subgroups revealed that in anoxic conditions periodontal strains tend to secret significant higher amounts of Sap than in normoxic conditions (p < 0.0001). However, this superior secretion rate is not different from those obtained for non-periodontal strains grown in normoxic or anoxic conditions. CONCLUSION: There is a possibility of adaptation or selection of C. albicans strains by the periodontal microenvironment. This study was supported by grants supplied by Araucaria Foundation (Process 9042), Coordination for the Improvement of Higher Education Personnel (CAPES Process BEX 0559/06-7), and intramural funds from OBU-PPDH-HKU.link_to_OA_fulltextThe 89th General Session and Exhibition of IADR/AADR/CADR, San Diego, CA., 16-19 March 2011

Reducing the negative effects of chemical polishing in acrylic resins by use of an additional cycle of polymerization

Statement of problem. The chemical polishing of dentures and orthodontic appliances is an efficient and time-saving technique. However, the process may adversely affect the physical properties of resin. Purpose. This study evaluated the effect of an additional polymerization cycle in a microwave or water bath on the physical properties of an autopolymerized acrylic resin submitted to chemical polishing. Material and methods. Control groups comprised acrylic resin specimens submitted to mechanical (group 1) and chemical (group 2) polishing. Experimental groups comprised chemically polished specimens submitted to an additional cycle of polymerization in a microwave at 450 W for 3 minutes (group 3) or in a hot water bath at 65degrees C for 1 hour (group 4). For the residual monomer test, 10 standardized half-disc specimens (30 x 3 mm) were fabricated for each of the test groups, and daily ultraviolet spectrophotometric (206 nm) analyses were assessed for 13 days (mug/cm(2)). For transverse strength and internal Knoop hardness (KH) tests, 10 (65 x 10 x 2.5 mm) and 5 (32 x 10 x 2.5 mm) specimens were fabricated for each test group, respectively. Internal Knoop hardness (kg/mm(2)) was assessed at depths of 100, 700, and 1500 mum. Transverse strength (MPa) was measured with a 3-point bending test in a universal testing machine with a 10-kg load cell at a crosshead speed of 5 mm/min. The data were analyzed with 1-way analysis of variance, and the means were compared with Student's t test and Tukey-Kramer intervals (P<.05). Results. At the end of the first day of the test, all groups showed significantly different residual monomer levels (P<.05). The groups in order of decreasing residual monomer were: group 2 (1315.7 +/- 225.5 mug/cm(2)), group 3 (848.2 +/- 150.4 mug/cm(2)), group 4 (295.1 +/- 81.6 mug/cm(2)), and group 1 (136.6 +/- 45.5 mug/cm(2)). After 13 days of water storage, the lowest residual monomer levels were recorded for group 1 (4.6 +/- 1.6 mug/cm(2)). There were no significant differences among group 2 (11.3 +/- 3.1 mug/cm(2)), group 3 (9.6 +/- 1.5 mug/cm(2)), and group 4 (12.3 +/- 1.7 mug/cm(2)). Group 1 demonstrated the highest transverse strength (78.1 +/- 6.1 MPa); the other groups were not significantly different from each other. All groups exhibited lower KH values at the 100-mum depth than at 700- and 1500-mum depths. At the latter depths, group 4 specimens demonstrated the highest 2 hardness values (18.9 +/- 0.5 and 18.8 +/- 0.7 mug/mm(2), respectively). Conclusion. Within the limitations of this study, additional polymerization with hot water reduced residual monomer content of chemically polished acrylic resins on the first day. Although additional polymerization increased the internal hardness of the material, however, it did not recover the transverse strength that was decreased by the chemical polishing.89659860

Brazilian Nursing Team: Quality of Working Life and The Leadership Influence

Objective: Analyzing the relation between the nurses-in-chief managerial styles with the Quality of Working Life (QWL). The balance between quality of life and work brings some sub-dimensions between life outside the workplace and work itself. Most of the investigated studies address the impact of work on life and the impact of life on the job. This analysis is important, as it contributes to several aspects, such as, for example, to increase the level of activity or participation. Materials and methods: Cross-sectional, qualitative, explanatory, and descriptive study. The sample was 61 nursing professionals (RNs) who held board positions, heads of department, managers, unit areas coordinators or supervisors, executive boards and/or departments, and 134 Licensed Practical Nurses (LPN) at a hospital with a direct public administration in Brazil. The data collection was based on The Quality of Working Life Questionnaire (QWLQ-brief) and the Scale of Evaluation of the Managerial Style (SEMS) forwarded electronically. Results: The indices considered satisfactory begin from 55 points. The QWLQ-brief average was 46,39% (neutral position), and the physical/health aspects were considered unsatisfactory (mean 44,89%; 44, 13%).Conclusion: The conclusion showed relational possibilities between the Nurse-in-chief managerial style and the perception of the Quality of Working Life. The perception of the neutral life quality and some unsatisfactory sub-dimensions was related to the managerial style based on tasks