Makoto Shibagaki

Modified procedure of a direct in vitro exposure system for mammalian cells to whole cigarette smoke

In vitro biological studies on cigarette smoke have usually been made using either cigarette smoke condensate--obtained by trapping the particulate phase of smoke on a filter, or soluble smoke components--obtained by trapping cigarette smoke in buffer solution. However, these approaches may not truly reflect the physical and chemical condition of freshly generated smoke. Clearly it is important to be able to evaluate the biological effects of fresh smoke on mammalian cells for a better understanding of the potential effects of smoking. The CULTEX technology is a new experimental system for cultivation and exposure techniques enhanced the efficiency of in vitro studies, and allows direct exposure of cells intermittently at the air/liquid interface with ultrafine particles, gases, or mixtures of both which fixedly flows. The CULTEX technology has therefore been modified to evaluate the biological effects of whole cigarette smoke in an in vitro system. The exposure system design was based on a combination of the sedimentation procedure and the CULTEX cultivation technique. After freshly generated smoke was delivered onto cells, the flow was shut off and the medium was slowly removed. In this manner, cells were exposed to both the vapor and particulate phase of smoke efficiently. Cells were maintained in the liquid medium except during the exposure period to maintain the culture conditions and to protect the cells from both the influence of puff pressure and the airflow, which served to remove residual cigarette smoke. The medium was changed at every puff of smoke and so effectively eliminating the possibility of any effects caused by accumulation of soluble cigarette smoke components into the medium. This cycle was repeated and cells were exposed to freshly generated cigarette smoke intermittently.

Inhibitory effects of 3-nitro-2,4,6-trihydroxybenzamides on Epstein-Barr virus early antigen induction

Inhibitory effects of a series of 3-nitro-2,4,6-trihydroxybenzamides on Epstein-Barr virus early antigen (EBV-EA) induction were examined using Raji cells. Some of the tested compounds showed highly inhibitory activity, the N-octyl amide derivative being the most active among them. These results suggest the possibility that 3-nitro-2,4,6-trihydroxybenzamides might be listed as novel inhibitors of tumor promotion.

Regioselective hydrogenation using platinum-support zeolite modified by CVD-method

Abstract Platinum-support zeolites coupled with silicon alkoxides were prepared by the Chemical Vapor Deposition (CVD) method. With this catalyst system, it was demonstrated that the terminal carbon-carbon double bond is preferentially hydrogenated in the case of several unsaturated hydrocarbons. Further, it was elucidated that highly regioselective hydrogenation of alkadiene could also be achieved in this catalyst system.

Inhibitory effects of 3-nitrophloroglucinecarboxylic acid derivatives on Epstein-Barr virus early antigen induction.

The inhibitory effects of two series of 3-nitrophloroglucinecarboxylic acid derivatives, 3-nitro-2,4,6-trihydroxythiobenzamides (II) and 3-nitro-phloroglucinecarboxylates (III), on Epstein-Barr virus early antigen (EBV-EA) induction were examined using Raji cells. Some of them strongly inhibited the induction, N-nonyl and O-decyl derivatives being the most potent inhibitors among the thioamides and esters, respectively. These results suggest the possibility that these two 3-nitrophloroglucinecarboxylic acid derivatives may be listed as novel inhibitors of tumor promotion.

Antipromoting effects of 5-lipoxygenase inhibitors, 3-nitro-2,4,6-trihydroxybenzamide derivatives, on TPA-promoted transformation in BALB 3T3 cells

In order to discover the role in the promotion process of 5-lipoxygenase (5-LO), a key enzyme in the arachidonate cascade, the antipromoting effects of the 5-LO inhibiting 3-nitro-2,4,6-trihydroxybenzamide (NTB) derivatives were studied in a two-stage transformation assay system using BALB 3T3 cells. All compounds inhibited TPA-promoted transformation in a dose-dependent manner. Most of them achieved a 70-80% inhibition. Good correlations were observed between the inhibition of TPA-promoted transformation and that of 5-LO. These results indicate that 5-LO plays an important role in the promotion stage of the transformation of BALB 3T3 cells.

Synthesis of a useful chiral building block, (S)-5-acetoxy-2-penten-4-olide from D-glucose

A new method for preparation of (S)-5-acetoxy-2-penten-4-olide starting from D-glucose with 5 steps is described