In vitro metabolism of alectinib,a novel potent ALK inhibitor,in human: contribution of CYP3A enzymes

1.?The in vitro metabolism of alectinib, a potent and highly selective oral anaplastic lymphoma kinase inhibitor, was investigated.

2.?The main metabolite (M4) in primary human hepatocytes was identified, which is produced by deethylation at the morpholine ring. Three minor metabolites (M6, M1a, and M1b) were also identified, and a minor peak of hydroxylated alectinib (M5) was detected as a possible precursor of M4, M1a, and M1b.

3.?M4, an important active major metabolite, was produced and further metabolized to M6 by CYP3A, indicating that CYP3A enzymes were the principal contributors to this route. M5 is possibly produced by CYP3A and other isoforms as the primary step in metabolism, followed by oxidation to M4 mainly by CYP3A. Alternatively, M5 could be oxidized to M1a and M1b via an NAD-dependent process. None of the non-CYP3A-mediated metabolism appeared to be major.

4.?In conclusion, this study suggests that involvement of multiple enzymes in the metabolism of alectinib reduces its potential for drug–drug interactions.     

Elevated serum IgG titer and avidity to Actinobacillus actinomycetemcomitans serotype c in Japanese periodontitis patients

AIM: The purpose of this study was to characterize serum antibody responses to different serotypes of Actinobacillus actinomycetemcomitans strains in various forms of periodontitis and to determine whether any specific type of A. actinomycetemcomitans was associated with any specific form of periodontitis in a Japanese population. METHODS: Sonicated whole cell and autoclaved serotype antigens of A. actinomycetemcomitans were used. Serum IgG titer and avidity to A. actinomycetemcomitans were measured by enzyme-linked immunoabsorbant assay (ELISA) and ammonium thiocyanate-dissociation ELISA, respectively, in 46 aggressive periodontitis patients (8 localized, 38 generalized), 28 chronic periodontitis patients, and 18 periodontally healthy subjects. The presence of A. actinomycetemcomitans in plaque and saliva samples was determined using polymerase chain reaction. RESULTS: Generalized aggressive and chronic periodontitis patients exhibited significantly higher IgG titers than healthy subjects to both sonicated and autoclaved antigens of serotype c strains, while IgG titer to serotype b (Y4) was significantly higher in localized aggressive periodontitis patients compared to healthy subjects. No A. actinomycetemcomitans was detected in localized aggressive periodontitis patients. A. actinomycetemcomitans-positive patients exhibited significantly higher IgG titer and avidity to serotype c than A. actinomycetemcomitans-negative patients. In A. actinomycetemcomitans-positive patients, a significantly positive correlation was observed between antibody titer and avidity to serotype c. A. actinomycetemcomitans-positive patients with generalized aggressive periodontitis showed lower IgG avidities to serotype c than those with chronic periodontitis, though no statistically significant difference was found. CONCLUSION: A. actinomycetemcomitans serotype c may play a significant role in chronic and generalized aggressive periodontitis, while A. actinomycetemcomitans serotype b may be associated with localized aggressive periodontitis in a Japanese population.     

Relationship between Af temperature and load changes in Ni-Ti orthodontic wire under different thermomechanical conditions

Simple three point bending tests were performed on Ni-Ti wires with three different Af points (1 degree C, 13 degrees C and 34 degrees C) to clarify the relationship between Af temperature and load changes under constant deformation. Each wire was deformed at 37 degrees C and then thermal changes were imposed by temperatures of 2 degrees C or 60 degrees C. The load changes with thermal changes from 37 degrees C to 2 degrees C or 60 degrees C showed the same tendency on the wires with different Af points: In the loading stage, the load became lower than the initial level at 37 degrees C and in the unloading stage, the load became higher than the initial load. The largest load change in the unloading stage was measured with the 13 degrees C Af point wire. Care must be taken when handling Ni-Ti wire with an Af point of less than 1 degree C in order to prevent it from reaching the limit of critical stress of slip deformation when the temperature in the mouth rises to above 40 degrees C.     

An immunohistochemical study of the distribution of immunocompetent cells, especially macrophages and Ia antigen-expressing cells of heterogeneous populations, in normal rat molar pulp.

The precise distribution of various immunocompetent cells in rat molar pulp was immunohistochemically examined by use of seven anti-rat monoclonal antibodies. It was demonstrated that rat molar pulp contained many OX6 (anti-Ia antigen)-positive cells and a large number of ED1 (anti-monocytes, macrophages, and dendritic cells)-positive, ED2 (anti-tissue macrophages)-positive, and/or OX35 (anti-macrophages and CD4+ lymphocytes)-positive cells. Macrophage-like cells predominated in the central portion of the pulp, while cells of dendritic appearance usually existed in the periphery of the pulp. Double-immunoperoxidase staining revealed that these cells showed some heterogeneity, but the majority could be classified as ED1+/OX6-/ED2+ cells, which may be Ia-histiocytes. Findings also suggested that true dendritic cells may be included in the ED1+/OX6+/ED2- category of cells. A small number of T lymphocytes and plasma cells were also detected. These results suggest that the normal dental pulp contains a variety of immunocompetent cells, with macrophages as the most dominating. Following the exogenous invasion of pathogenic stimuli in the pulp, these cells may participate in the defense reaction by acting as phagocytes or antigen-presenting cells, which are essential for the initiation of immune responses.