Tetsuhito Fukushima

Mechanism of cytotoxicity of paraquat

Acute paraquat poisoning seems to be very complex because many possible mechanisms of paraquat cytotoxicity have been reported. Some may not be the cause of paraquat poisoning but the result or an accompanying phenomenon of paraquat action. The mechanism critical for cell damage is still unknown. Paraquat poisoning is probably a combination of several paraquat actions. Arguing which mechanism is more critical may not be important, and these clarified mechanisms should be connected and utilized in the development of treatment for paraquat poisoning. Many people still die of pulmonary fibrosis after paraquat exposure. The next target of study will be to verify the mechanism of pulmonary fibrosis by paraquat on the basis of the outcome of studies such as this review.

Possible role of 1-methylnicotinamide in the pathogenesis of Parkinson's disease.

This study tested the hypothesis, that nicotinamide N-methyltransferase (NAMT) activity in the brain could convert nicotinamide to 1-methylnicotinamide (MNA) and by that means damage the nigro-neostriatal dopaminergic neurons. The NAMT activities of rat brain and liver were assayed with gas chromatographic-mass spectrometric analysis in a selected ion monitoring system. They amounted to 0.30 nmol/mg x h and 0.51 nmol/mg x h, respectively. The MNA injection in rat substantia nigra pars compacta significantly decreased dopamine content in the striatum. NADH oxidation and lipid peroxidation by MNA via rat brain submitochondrial particles (SMP) under the condition of pH ranging from pH 6.0 to 10.0 were verified. The pH optimum for the NADH oxidation was 9.0. The pH optimum for the peroxidation of the lipid composing SMP by MNA was also 9.0. The lipid peroxidation in this assay was suppressed by superoxide dismutase. The superoxide anion formed by MNA via mitochondria might be involved in the etiology of Parkinsons disease.

Correlations among heavy metals in blood and urine and their relations to depressive symptoms in Parkinson's disease patients

OBJECTIVESnFrom our previous results, manganese (Mn) and iron (Fe) in the blood of Parkinsons disease (PD) patients without depression were higher than those of both the PD patients with depression and controls, the hypothesis that two types of PD exist-PD without depression and affected by Mn and Fe, and PD with depression and unaffected by Mn or Fe was induced. To investigate the hypothesis, correlations among blood and urine metals were compared in the subjects.nnnMETHODSnSubjects comprised PD patients with depression, PD patients without depression and controls recruited from an outpatient clinic in China. Morning blood and urine samples were used to measure concentrations of metals.nnnRESULTSnIn the controls, Mn, Fe and zinc (Zn) levels in blood strongly correlated with each other. The correlation coefficient between Mn and Zn in blood was significant in the PD patients with depression and the controls, but not in the PD patients without depression. Correlations of Fe between blood and urine in the PD patients without depression were significant, but not in the PD patients with depression and the controls.nnnCONCLUSIONSnA common route of simultaneous intake of Mn, Fe and Zn could exist in our subjects, however in PD patients without depression, a large intake of Mn may have been from another route. Some results of the PD patients without depression were different from those of the PD patients with depression and the controls. Thus, two types of PD may exist.

The Taxonomic Study of Diphyllobothriid Cestodes with Special Reference to Diphyllobothrium nihonkaiense in Japan

The epidemiological features of diphyllobothriosis nihonkaiense are described. The case incidence showed peaks in the 1920s, 1970s, and 1980s. The geographic distribution covers all Japan. The main subjective symptoms are evacuation (83%), diarrhea or loose bowels (14%), and abdominal pain (13%). The taxonomic features of Diphyllobothrium nihonkaiense are described according to the following points: the shape and size of the scolex, bothrium development, neck length, segment form and size, segmental surface structure, internal structure, form and size of egg, pattern of egg-surface pits, growth condition of coracidia, form and size of hooks of the hexacanth embryo, form and size of the plerocercoid, bothrial slit, and tail excavation, and transverse furrows of the body surface. As for the internal structure of the plerocercoid, microtriches, the subtegumental and longitudinal muscle layer, parenchymal longitudinal muscle layer, subtegumental cell layer, and distribution of frontal gland showed as marked features. The physiological, biochemical, and molecular phylogenic features have been applied to species identification. We have tried to analyze the trace element content, amino acid content, isozyme pattern, immunological specificity, and DNA sequences. The natural focus of D. nihonkaiense is not yet defined, but the intermediate host, the masu salmon, Oncorhynchus masou, spawns all around the Sea of Okhotsk and the Sea of Japan.