Spectrophotometric Analysis of Apical Extrusion of Sodium Hypochlorite using Different Irrigation Protocols in an Ex Vivo Model of Immature Teeth.

OBJECTIVE: To evaluate the effect of different agitation methods on apical extrusion of 1.5% sodium hypochlorite (NaOCl) in an ex vivo model of immature teeth. METHODS: Sixty extracted human inferior incisors were prepared to simulate immature teeth and embedded in an artificial root socket made of silicone impression material. The teeth were then divided into four groups: Conventional needle irrigation (CNI) alone, CNI supplemented with Ultrasonic Irrigant Activation (UIA), EasyClean (EC), or XP-endo Finisher (XPF). Extruded NaOCl was collected, reacted with m-cresol purple, and its absorbance values were measured. The data were statistically analyzed using One-way analysis of variance with a significance level of 5%. RESULTS: All groups showed apically extruded irrigating solution, and the mean volumes of extruded NaOCl did not differ significantly between any of the test groups (p⟩0.05). CONCLUSION: The activation of 1.5% NaOCL by UIA, EC, or XPF as supplementary to CNI does not promote greater apical extrusion when compared to CNI alone in simulated immature teeth.

A human hepatocellular carcinoma 3.0-kilobase DNA sequence transforms both rat liver cells and NIH3T3 fibroblasts and encodes a 52-kilodalton protein.

Neoplastic transformation of rat liver cells in vitro by DNA-mediated gene transfer with an oncogene, hhcM, derived from human (Mahlavu) hepatocellular carcinoma, is described and compared with that of NIH3T3 cells. hhcM was cloned in a neomycin-resistant simian virus 40 promoter vector (pNeor/S) and was designated pNrpM-1. BRL-1 or NIH3T3 cells, transfected with pNrpM-1 DNA, showed significant morphological changes, loss of contact inhibition, and anchorage-independent growth. They became highly tumorigenic in nude rats and nu/nu mice. Control BRL-1 and NIH3T3 cells, whether transfected with pNeor/S DNA or not, remained contact inhibited and nontumorigenic. Both the transformants and the tumor cells contained integrated hhcM DNA as shown by Southern blot hybridization. The complete nucleotide sequence of the hhcM 3.0-kilobase DNA was also determined, and it consisted of a possible open reading frame for a protein of 52 kilodaltons (467 amino acids). The high-level production of a slightly modified form of this 52-kilodalton protein in a bacterial expression system has been successfully achieved. The bacteria-produced protein was similar in electrophoretic behavior to the 52- to 53-kilodalton protein synthesized in a cell-free translation system using rabbit reticulocyte lysate programmed with hybrid-selected hhcM-specific mRNA from Mahlavu hepatocellular carcinoma cells.