Biomedical subjects

Tetsuya Kusuda

Publications and source records attributed to Tetsuya Kusuda.

4 recordsLinked to original sources

PubMed2006

Effect of particulate biodegradable COD in a post-denitrification enhanced biological phosphorus removal system.

This research studied the effects of the particulate biodegradable fraction (X(S)) of chemical oxygen demand (COD) in a post-denitrification configuration. Denitrifying polyphosphate-accumulating organisms (DN-PAOs) and nitrifiers were completely separated in a system also known as Dephanox. It was composed by an anaerobic-anoxic (A(2)) process coupled with a parallel Nitrification biofilm tank. The results of a long-term operation of the Dephanox continuous-flow lab-scale system as well as results of sludge characterization assays showed that raw wastewater feeding promoted complete phosphorus (P) removal by double via (i) providing complementary volatile fatty acids (VFAs) for a complete P removal by prefermentation of the X(S) fraction of COD under a long anaerobic SRT, and (ii) assisting the metabolic accumulation and selection of DN-PAOs. Complete P removal was accomplished only when the system was fed with raw wastewater (high XS concentration). When primary effluent was used as influent, lack of VFAs in the anaerobic stage led to an incomplete and instable P removal, suggesting that the use of primary treatment is not only unnecessary but detrimental for simultaneous nutrient removal in a post-denitrification configuration.

Aerobiosis↗

PubMed2006

Arsenic in drinking water and peripheral nerve conduction velocity among residents of a chronically arsenic-affected area in Inner Mongolia.

BACKGROUND: It remains unclear whether chronic ingestion of arsenic in drinking water affects the peripheral nervous system. We examined the effects of arsenic exposure on nerve conduction velocity using electromyography. METHODS: A cross-sectional study was conducted of a population living in an arsenic-affected village in Hetao Plain, Inner Mongolia, China. A total of 134 (93.7%) of 143 inhabitants took part in the study, and 36 (76.6%) of 47 inhabitants in a low-arsenic exposed village were recruited as a control group. Of the participants, 109 inhabitants in the arsenic-affected village and 32 in the low-arsenic exposed village aged > or =18 years were used for the analyses. An expert physician performed skin examinations, and median nerve conduction velocity was examined by electromyography. Arsenic levels in tube-well water and urine were measured. A mean level of arsenic in tube-well water in the arsenic-affected village was 158.3 microg/L, while that in the low-arsenic exposed village was 5.3 microg/L. RESULTS: No significant differences in the means of the motor nerve conduction velocity (MCV) and sensory nerve conduction velocity (SCV) were observed in relation to arsenic levels in tube wells, urine, and the duration of tube-well use. Further, no differences in mean MCV or SCV were found between the subjects with and without arsenic dermatosis, with mean SCV of 52.8 m/s (SD 6.3) in those without and 54.6 m/s (5.2) in subjects with arsenic dermatosis (p=0.206). CONCLUSION: These findings suggest that chronic arsenic poisoning from drinking water is unlikely to affect nerve conduction velocity, at least within the range of arsenic in drinking water examined in the present study.

Adolescent↗

PubMed2005

Chronic arsenic exposure and urinary 8-hydroxy-2'-deoxyguanosine in an arsenic-affected area in Inner Mongolia, China.

OBJECTIVE: Recent studies have shown that generation of reactive oxidants during arsenic metabolism can play an important role in arsenic-induced injury. The purpose of this study was to examine the relationship between arsenic in drinking water and oxidative stress in humans by measuring 8-Hydroxy-2'-deoxyguanosine (8-OHdG). METHODS: We performed a cross-sectional study in an arsenic-affected village in Hetao Plain, Inner Mongolia, China. A total of 134 of the 143 inhabitants (93.7%) of the village participated in the study. The levels of 8-OHdG, arsenic and its metabolites were measured in urine collected from the participants. Regression analyses were performed to investigate the relationship between arsenic species and 8-OHdG levels in urine. RESULTS: In the polluted village, monomethylarsenic was significantly higher in subjects with arsenic dermatosis than those without dermatosis despite no difference in mean levels of arsenic in well water between both types of subject. For subjects with arsenic dermatosis, arsenic species and metabolites in urine are significantly associated with 8-OHdG, while there was no statistically significant relationship for subjects without arsenic dermatosis. For all residents of the polluted village, the levels of dimethylarsenic and 8-OHdG were significantly higher for those who had been exposed to well water for more than 12 years. CONCLUSIONS: These results provide evidence of a link between exposure to arsenic from drinking water and oxidative stress, which may play an important role in arsenic-involved injuries.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2004

Promoting nitrification by using functional gel as immobilizing medium under different temperature stimulation patterns.

Nitrification with nitrifiers immobilized by temperature stimuli-responsive N-isopropylacrylamide-Chlorophyll (NIPA-CH) gel was investigated under several patterns of temperature stimulation, compared with that at constant temperature. The results show that in response to a cyclic temperature stimulus of 32-36 degrees C or 32-34 degrees C with a period of 4 or 2 h, respectively, the gel swelled and shrank reversibly and promoted biological nitrification. But in the case of a cyclic temperature change of 32-36 degrees C with a stimulation cycle of 2 h, nitrite oxidization declined. The results suggested that adequate stimulus facilitated substrate transfer into gels that promoted nitrification in the reactor, but quite frequent swelling and shrinking of the gel squeezed nitrifier out of the gel resulting in washing nitrifier out and declining nitrification. When gels that undergone cyclic temperature stimuli began to swell at 32 degrees C, oxygen consumption of nitrifiers in the gels was more than that of nitrifiers in the gels at constant temperature of 32 degrees C all the time, but when gels of two reactors shrank at 36 degrees C, their oxygen consumption reduced and there was almost no difference between them regardless of their undergone temperature stimuli once or not. Practical application of nitrifier immobilized by NIPA-CH gel in wastewater treatment was also discussed.

Acrylamides↗