Purification, Gene Cloning, Gene Expression, and Mutants of Dps from the Obligate Anaerobe Porphyromonas gingivalis

The periodontopathogen Porphyromonas gingivalis is an obligate anaerobe that is devoid of catalase but exhibits a relatively high degree of resistance to peroxide stress. In the present study, we demonstrate that P. gingivalis contains a Dps homologue that plays an important role in the protection of cells from peroxide stress. The Dps protein isolated from P. gingivalis displayed a ferritin-like spherical polymer consisting of 19-kDa subunits. Molecular cloning and sequencing of the gene encoding this protein revealed that it had a high similarity in nucleotide and amino acid sequences to Dps proteins from other species. The expression of Dps was significantly increased by exposure of P. gingivalis to atmospheric oxygen in an OxyR-dependent manner, indicating that it is regulated by the reactive oxygen species-regulating gene oxyR. The Dps-deficient mutants, including the dps single mutant and the ftn dps double mutant, showed no viability loss upon exposure to atmospheric oxygen for 6 h. In contrast to the wild type, however, these mutants exhibited the high susceptibility to hydrogen peroxide, thereby disrupting the viability. On the other hand, no significant difference in sensitivity to mitomycin C and metronidazole was observed between the wild type and the mutants. Furthermore, the dps single mutant, compared with the wild type, showed a lower viability in infected human umbilical vein endothelial cells

Postoperative Bleeding after Tooth Extractions in Patients Controlled with Warfarin ? : A Clinico-statistical Study on the Factors Influencing Postoperative Bleeding?

There are many reports about tooth extractions of patients taking warfarin?, however PT-INR level is used to examine the postoperative bleeding in patients. To investigate other factors, postoperative bleeding, age, gender, PT- NR level, combined use of antiplatelet drugs, conditions of extracted tooth, a number of tooth extractions at a treatment, methods of management for warfarin? therapy, degree of the alveolar bone loss and size of radiolucency of apical region were examined in this study. To apply Mann-Whitney U-test andx2-test, ninety-three patients (38 male and 55 female) who took warfarin? and visited our clinic for tooth extractions from April 1994 to November 2002 were classified into 2 groups : One group showed hemostasis by the next day (77 patients), the other showed the continuous bleeding after the next day (16 patients). These analyses indicated that PT-INR level, a number of tooth extractions at a treatment, methods of management for warfarin* therapy, and size of radiolucency of apical region influenced postoperative bleeding. In addition, stepwise logistic regression analysis was applied to all of the factors, obtained from 77 patients out of 93 patients. This data showed that PT-INR level, a number of tooth extractions at a treatment and methods of management for warfarin? therapy influenced postoperative bleeding. These results suggest that before the tooth extractions not only PT-INR level but methods of management for warfarin? therapy and size of wound could be important to control the postoperative bleeding in warfarin? taking patients

Multiple calcium channels regulate neurotransmitter release from vagus nerve terminals in the cat bronchiole

1. Twitch-like contractions and non-adrenergic non-cholinergic (NANC) relaxations evoked by electrical field stimulation (EFS) of the cat bronchiole were used to examine the voltage-activated calcium channels involved in excitatory and inhibitory neurotransmission in the cat bronchiole. 2. Nifedipine (50 μM), the L-type calcium channel antagonist, did not affect the twitch-like contraction and NANC relaxations. However, low concentrations of the N-type calcium channel blocker ω-conotoxin GVIA (ω-CgTX GVIA) (0.1 μM) irreversibly abolished twitch-like contractions evoked by trains of EFS ⩽10 stimuli at 20 Hz. 3. After the prolonged treatment with 0.1 μM ω-CgTX GVIA, EFS evoked initial fast and later slow NANC relaxations in the presence of 5-HT (10 μM), atropine and guanethidine (1 μM each). However increased concentration of ω-CgTX GVIA (1 μM) completely suppressed the slow NANC relaxation without affecting the initial fast component. 4. ω-agatoxin IVA (100 nM), the P- and Q-type calcium channel inhibitor, and nimodipine (10 μM), the L- and T-type calcium channel blocker, did not affect the amplitude of the initial fast NANC relaxation in the absence or presence of ω-CgTX GVIA (1 μM). 5. The contraction or relaxation induced by exogenous acetylcholine (ACh) (0.5 μM) or the nitric oxide donor, s-nitroso-N-acetyl penicillamine (SNAP) (1 μM) were not affected by ω-CgTX GVIA (1 μM). 6. Taken together, these results suggest that generation of twitch-like contraction and later slow NANC relaxation are regulated by N-type calcium channels, whereas generation of the initial fast NANC relaxation possibly involves R-type calcium channel

ワーファリン^®服用患者の抜歯後出血について : 後出血に影響を与える要因についての臨床統計的検討

There are many reports about tooth extractions of patients taking warfarin?, however PT-INR level is used to examine the postoperative bleeding in patients. To investigate other factors, postoperative bleeding, age, gender, PT- NR level, combined use of antiplatelet drugs, conditions of extracted tooth, a number of tooth extractions at a treatment, methods of management for warfarin? therapy, degree of the alveolar bone loss and size of radiolucency of apical region were examined in this study. To apply Mann-Whitney U-test andx2-test, ninety-three patients (38 male and 55 female) who took warfarin? and visited our clinic for tooth extractions from April 1994 to November 2002 were classified into 2 groups : One group showed hemostasis by the next day (77 patients), the other showed the continuous bleeding after the next day (16 patients). These analyses indicated that PT-INR level, a number of tooth extractions at a treatment, methods of management for warfarin* therapy, and size of radiolucency of apical region influenced postoperative bleeding. In addition, stepwise logistic regression analysis was applied to all of the factors, obtained from 77 patients out of 93 patients. This data showed that PT-INR level, a number of tooth extractions at a treatment and methods of management for warfarin? therapy influenced postoperative bleeding. These results suggest that before the tooth extractions not only PT-INR level but methods of management for warfarin? therapy and size of wound could be important to control the postoperative bleeding in warfarin? taking patients

The inhibitory effect of alendronate, a nitrogen-containing bisphosphonate on the PI3K–Akt–NFκB pathway in osteosarcoma cells

1. Bisphosphonates are inhibitors of tumor cell growth as well as of bone resorption by inducing cell apoptosis. However, little is known regarding the mechanisms by which the drug induces cell apoptosis. The aim of the present study was to determine the effect of alendronate, one of the nitrogen-containing bisphosphonates on the phoshoinositide 3-kinase (PI3K)–Akt–NFκB pathway, the major cell survival pathway. 2. The PI3K–Akt–NFκB pathway was activated in the osteosarcoma cell line MG-63 treated with tumor necrosis factor-α or insulin. Saos-2 was also used in some experiments. This was assessed by the production of phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3)), increased PI3K activity, phosphorylation of Akt at serine 473 and threonine 308, increase in activity of the inhibitor of nuclear factor κB (IκB) kinase (IKK) and finally phosphorylation of IκB and its subsequent degradation. 3. Pretreatment with alendronate at 100 μM for 24 h prior to the stimulation with tumor necrosis factor-α or insulin partially inhibited the IκB phosphorylation and degradation. These events were more clearly observed in the presence of inhibitors of proteasomes, which are responsible for the degradation of IκB. The drug also partially inhibited the activity of IKK, but almost fully inhibited the phosphorylation of Akt and the production of PtdIns(3,4,5)P(3). 4. The inhibitory effect of alendronate on IκB phosphorylation and degradation was not attenuated by the exogenous addition of geranylgeraniol to replenish the cytosolic isoprenyl lipid substrate. 5. The present findings demonstrate that alendronate inhibited the PI3K–Akt–NFκB cell survival pathway at the point of PI3K activation, thus indicating the presence of new targets of alendronate