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S Nakai

Publications and source records attributed to S Nakai.

311 records · Page 18Linked to original sources
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Exposure to nitrogen oxides and other air pollutants from automobiles.

We have conducted an epidemiological study to investigate the association between exposure to automobile exhaust and respiratory health. Three zones were selected in Tokyo according to expected exposure levels. Zone A is within 20 meters from the roadside of major roads with heavy traffic. Zone B is 20-150 meters away from the roadside of the same road. Zone C is the residential district in a suburb of Tokyo. Zone A, which was nearest to the roads, had the highest mean levels of personal exposure to nitrogen dioxide for housewives, followed by Zone B and Zone C. Ambient levels of nitrogen oxides, and mass concentrations, polycyclic aromatic hydrocarbons and mutagenicity of suspended particulate matter were higher at the roadside within Zone A. A cross-sectional study of respiratory symptoms and repeated examinations of pulmonary function were also performed in each zone. These results suggest that exposure to automobile exhaust may be associated with respiratory symptoms. Nevertheless, pulmonary function didn't show consistent differences over all examinations. We should have further analyses about a decline of pulmonary function with age.

Adult↗
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Respiratory health associated with exposure to automobile exhaust. II. Personal NO2 exposure levels according to distance from the roadside.

We have conducted several studies to investigate the effect of automobile exhaust on respiratory symptoms. This study was designed to explore differences in personal exposure levels among residents of zones located varying distances from trunk roads with heavy traffic in Tokyo. Personal nitrogen dioxide (NO2) concentration levels for residents and NO2 concentrations inside and outside the residences of each study participant were measured during ten seasons over three years. Three residential zones were determined as follows: Zone A was 0-20 m from the roadside; Zone B was 20-150 m; and Zone C, a reference zone, was a residential district in a suburban area. Approximately fifty residents were selected as the subjects of NO2 measurements. Study participants were female, between 40 and 60 years of age, and nonsmokers. All participants used gas cooking stoves with electric ignition. Outdoor NO2 concentrations in Zone A were always the greatest among the three zones during the study periods, and those in Zone C were consistently the lowest. Personal exposure levels in Zone A were generally higher than those in the other zones, and concentrations in Zone C were the lowest during seasons when no indoor heating was used. The highest mean values for personal exposure levels in Zones A, B, and C were 63.4, 61.0, and 55.3 ppb, respectively. In analyses in which participants were stratified by heater type, the mean personal exposure levels in Zone A were the highest and the levels in Zone C were the lowest for participants without unvented heaters; differences of NO2 levels between Zones A and C ranged from 10.0 to 23.9 ppb. When there were no indoor NO2 sources except gas cooking stoves, both indoor and personal levels of NO2 were attributable primarily to motor vehicle exhaust. In contrast, the use of unvented heaters during the heating seasons could cause NO2 exposures comparable to those attributable to motor vehicles.

Adult↗
PubMedDate not supplied

Relationship of protein catabolic rate or Kt/V with morbidity.

The authors investigated the influence of Kt/V and protein catabolic rate (PCR) on dialysis failure for 689 hemodialysis (HD) outpatients treated at the seven dialysis facilities in Aichi Prefecture, Japan. Dialysis failure was defined as death or hospitalization for reasons other than blood access, accident, wound, or mental disease. Patients were followed for 2 years. The rate of patients who developed dialysis failure during the observation period relative to the total patient population was defined as the dialysis failure rate. A total of 123 patients developed dialysis failure, which was fatal in 33 cases. In patients with Kt/V values of 1.6 or higher, the mean dialysis failure rate was significantly lower at 12.0% than that (19.2%) of patients with Kt/V values between 0.8 and 1.6 (p < 0.04). In patients that had PCR values under 0.8 g/kg/day, the dialysis failure rate was significantly higher at 32.5% than that (15.8%) of patients with PCR values between 0.8 and 1.4 g/kg/day (p < 0.0001).

Adult↗
PubMedDate not supplied

A new wearable system for continuous monitoring of arteriovenous fistulae.

A wearable system to constantly monitor the bruit generated by an AV fistula at times other than during dialysis was developed, and provided early detection of rapidly developing thrombi that cause occlusion of the fistular vessels. The system consists of a downsized microphone that continuously monitors the bruit generated, a warning device worn like a wristwatch, and a wire running down from the microphone to the emergency warning device. The microphone converts the bruit into an electrical signal and outputs it to the warning device. The emergency warning is then sounded whenever the input signal from the tiny microphone is weaker than a preset level. The warning device was set off in 4 of 21 long-term dialysis patients with arteriovenous fistulas, and within several hours all 4 developed an occlusion. One of the 14 patients with a graft had the device go off while sleeping, but it was a false alarm due to positioning that resulted in compression of the fistula arm.

Aged↗