The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability

Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) ≈500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) wide-spread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications

Resistencia adhesiva al cizallamiento de la aleación Ag-Pd a dentina de bovino

El objetivo de este estudio fue evaluar el comportamiento del cemento resinoso Bistite II DC,y de los agentes de adhesión al metal MetalTite y Alloy Primer para la unión entre la aleaciónde Ag-Pd a dentina de bovino. Se utilizaron 30 dientes de bovinos, incluídos en una resinaquimicamente activada y desgastados en la superficie vestibular hasta exponer un área suficientede dentina para realizar la cementación. Se confeccionaron cilindros a partir de la aleaciónPalliag M, de 3 mm de altura, 5 mm de diámetro y un alivio interno de 3 mm de diámetro conuna profundidad de 40 μm. Los cilindros fueron arenados con óxido de aluminio con particulasde 50 μm, luego fueron cementados y divididos en tres grupos. En el grupo control(C) no serealizó ningun tratamiento químico sobre la superficie metálica de los cilindros. En el grupoAlloy Primer (AP) y Metal Tite (MT) el tratamiento químico de la superfície fue realizadoconforme a las indicaciones de los fabricantes. Durante la cementación se aplicó una cargaestática de 5kg. Los especimenes fueron almacenados en atmósfera de 100% de humedaddurante 24 horas. La prueba mecánica fue realizado en una maquina universal de ensayosmecánicos DL-1000 (EMIC-Brasil) con una célula de carga de 1000 Kg a una velocidad de 1mm/minuto. Se realizó el test de Kruskal-Wallis (á?0,05), los resultados mostraron que los grupos C,MT y AP se comportaron de manera semejante al evaluar la resistencia al cizallamiento y eltipo de fractura que presentaron

Micromorphology of Restorative System-Dentin Interface in Primary Teeth Using Different Adhesive Systems and Burs

Objective: This study in vitro evaluated the micromorphology of the resin-dentin interface in primary teeth, using different rotatory instruments and adhesive systems. Method: Twenty primary molars were selected and randomly divided into two groups (n=10). In group C, the occlusal surfaces of teeth were cut with a carbide bur at high-speed until the area of dentin exposure. In group D, the same procedure was conducted, but the dentin was cut with a diamond bur. The surface of each tooth was divided into two halves; one half of the occlusal surface received application of two-step total-etch adhesive system (Single-Bond – 3M), and the other half received application of one-step self-etching adhesive (One Up Bond F - Tokuyama). All teeth were restored with composite (Z-250 - 3M). The samples were thermocycled, embedded in acrylic resin, sectioned for achievement of the resin-dentin interface and the teeth were sputter- coated with gold and observed under SEM. Results: the two adhesive systems showed hybrid layer formation; the two-step adhesive system demonstrated better interface sealing than the self-etching; the dentin cut with carbide burs was not statistically different with regard to the adhesive system; and diamond bur with self-etching adhesive system showed the worst interface sealing with the highest gap values. Conclusion: the diamond bur presented negative influence only in the quality of the interface between restorative system and primary dentin when it was used the one step self-etching adhesive system

Evaluation of a new intraoral paralleling device for creating guiding planes: A pilot study

Aim: The aim of the study was to assess the accuracy of a new intraoral paralleling device for creating proximal guiding planes for removable partial dental prostheses. Methods and Materials: Thirty gypsum casts were divided into two groups in which the proximal surfaces of selected teeth were prepared using either a surveying device (Group 1) or the new ParalAB paralleling device (Group 2). In each cast guiding planes were prepared on the distal surface of the maxillary left canine (A), on the mesial and distal surfaces of the maxillary left second molar (B and C), and on the distal surface of the maxillary right canine (D). Each prepared surface formed an angle related to the occlusal plane that was measured five times and averaged by one operator using a tridimensional coordinate machine. Results: The mean guiding plane angles (± standard deviation) for the prepared surfaces were A=91.82° (±0.48°, B=90.47° (±0.47°, C=90.21° (±0.76°, and D=90.50° (±0.73°) for the dental surveyor (Group 1) and A=92.18° (±0.87°), B=90.90° (±0.85°), C=90.07° (±0.92°), and D=90.66° (±0.76°) for the ParalAB paralleling device (Group 2). A two-way ANOVA, Tukey's, and Levène's tests (at p<0.05) revealed statistically significant differences among surfaces prepared by both groups and that one surface Conclusions: The ParalAB device was able to prepare parallel surfaces and despite significant difference between groups, the ParalAB presented a small deviation from absolute parallelism and can be considered a valid method to transfer guide plans in the fabrication of removable partial dentures. Clinical Significance: The preparation of suitable guiding planes on abutment teeth during the fabrication of removable partial dentures is dependent on the ability of the operator and requires considerable chair time. When multiple teeth are involved, achieving parallelism between abutment surfaces can be technically challenging, especially in posterior regions of the mouth. The ParalAB prototype intraoral paralleling device can aid the clinician during the preparation of accurate guiding planes with a minimum degree of occlusal divergence. © 2010 Seer Publishing LLC