Semiconducting and metallic single-walled carbon nanotubes (s-SWNTs and m-SWNTs) were enriched by agarose gel chromatography and their photothermal and photodynamic effects were compared in H(2)O. Under near-infrared laser irradiation, s-SWNTs generated reactive oxygen species (ROS) more than m-SWNTs, whereas m-SWNTs produced heat more efficiently than s-SWNTs. More importantly, cancer cell killing by PDE of s-SWNTs has been disclosed for the first time.

Iodine-123-labelled 3beta-(4-iodophenyl)tropane-2beta-carboxylic acid ([123I]beta-CIT) labels both the dopamine transporter (DAT) and the serotonin transporter (5-HTT) and this ligand is able to clarify pathological changes in both dopaminergic and serotonergic systems. However, the differential kinetics of beta-CIT binding to DAT and 5-HTT has not been clarified fully. In this study we examined time-activity curves of [123I]beta-CIT in individual regions in the rat brain. Using cerebellum as the reference region, k3 and k4 values were estimated by a two-compartment kinetic analysis. In the striatum, the kinetics was slowest among all brain areas. In this area specific binding reached its peak 4 h after the injection. In the hypothalamus, specific binding reached its peak 1 h after the injection and its amount did not change until 4 h after the injection. In the occipital cortex, the binding and washout of the ligand were fastest among all brain regions. Estimated k3 values were 0.040+/-0.003 in the striatum, 0.019+/-0.002 in the hypothalamus and 0.082+/-0.011 in the occipital cortex (min-1, mean +/-SD). Estimated k4 values were 0.0034+/-0.0005 in the striatum, 0.0071+/-0.0009 in the hypothalamus and 0.083+/-0.013 in the occipital cortex (min-1, mean +/-SD). Therefore binding kinetics of [123i]beta-cit in the region rich in dat is apparently different from that in the region rich in 5-HTT. These results will provide fundamental data to image both DAT and 5-HTT in one series of examinations with [123I]beta-CIT.

-Effectsof Panax ginseng on the spontaneous motor activity and central dopaminergic systems in old rats were investigated and compared with those in young rats. Oral intake of a 1.8% water extract of Panax ginseng for four weeks produced an increase in spontaneous motor activity during the dark period in old rats, while it caused a decrease in the activity in young rats. After the intake of ginseng extract for five weeks, it caused a significantly low dopamine utilization in the daytime in the striatum of old rats, while it produced a high dopamine utilization in the structure of young rats. Concentrations of striatal dopamine D-2 receptors in old rats were significantly lower than that in young rats, although subchronic Panax ginseng did not affect the striatal D-1 and D-2 receptors of old rats. These results suggest that subchronic intake of ginseng extract inhibits the activity of nigro-striatal dopamine neurons in the daytime and activates spontaneous motor activity during the dark period in old rats, while it produces opposite effects in young rats.Panax ginseng root produces various neuropharmacological effects such as changes in brain biogenic amines, improvement of learning and memory retention (1), promotion of recovery from fatigue (ref. A decrease in motor activity was shown in aged mice in association with an increase in monoamine oxidase activity in the brain (6). Impairment of swimming ability, which was similar to that seen after electrolesion of the lateral hypothalamus including the nigro-striatal dopaminergic neurons, was observed in aged rats (7). Diminution of synthesis, release and re-uptake of dopamine and decrease in D-2 dopamine receptors in the striatum were reported in aged animals (8-11).We investigated the effects of a water extract of Panax ginseng root on spontaneous motor activity and nigro-striatal dopaminergic nervous systems in two year-old rats and compared them with those in young rats. MATERIALS AND METHODSYoung and old male Fischer 344 rats (3 and 24 months old at the end of the experiment, respectively; Nippon Charles River, Tokyo) were used. They were kept under an alternat-

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The effects of MK-801, a noncompetitive NMDA receptor antagonist, on in vivo and in vitro binding of radioactive iodine ([123I] or [125I]) labeled beta-CIT [RTI-55, 3beta-(4-iodophenyl)tropane-2beta-carboxylic acid methyl ester] were investigated in rat brain. In the in vitro binding study, 10 pM of [125I]beta-CIT was incubated with either 0.03 microM or 3 microM of MK-801 at 24 degrees C for 60 min. In vitro, no alterations in [125I]beta-CIT binding in any region of rat brain slices were detected after addition of MK-801. In the in vivo binding study, [123I]beta-CIT was intravenously injected into rats 30 min after intraperitoneal injection of 0.03-1 mg/kg of MK-801. The in vivo [123I]beta-CIT binding in the striatum, frontal cortex, occipital cortex, hypothalamus, and thalamus was significantly increased by pretreatment with 1 mg/kg of MK-801. Kinetic analysis using the cerebellum as a reference region revealed that the increases in in vivo [123I]beta-CIT binding induced by MK-801 were mainly due to increases in both input rate constant k3 and output rate constant k4. The results of this study indicate that the glutamatergic system, including NMDA receptor, plays an important role in regulating neurotransmission in the dopaminergic or serotonergic systems in intact brain.