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Biomedical subjects

S Nakai

Publications and source records attributed to S Nakai.

At least 307 records · Page 17Linked to original sources

Bronchial lesions of the late asthmatic response in BALB/c and C57BL/6 mice.

In this study, histopathological bronchial-bronchiolar lesions of the late asthmatic responses induced by ovalbumin in BALB/c and C57BL/6 mice were compared. Prominent goblet cell hyperplasia and metaplasia with mucous secretion, and desquamation of epithelial cells with severe infiltration of eosinophils and lymphocytes, were observed in the BALB/c mice; in the C57BL/6 mice, however, these changes were less severe. The reduced histopathological changes in the C57BL/6 mice were associated with a decreased infiltrate of eosinophils, decreased serum immunoglobulin-E (IgE) concentrations and increased serum interferon-gamma concentrations. The results suggest that the reduced bronchial lesions in C57BL/6 mice were due, at least in part, to suppression of the T-helper (Th)2 immune response that underlies the decreased infiltration of lymphocytes and eosinophils into the bronchial mucosa.

Animals↗

Respiratory health associated with exposure to automobile exhaust. I. Results of cross-sectional studies in 1979, 1982, and 1983.

Three cross-sectional studies were conducted in an effort to investigate the effect of automobile exhaust on respiratory symptoms. Female adult subjects were selected from residents who lived near roadways that were subjected to very heavy traffic. A standard questionnaire was administered to approximately 5,000 people. Distances of the residences from the roadside were adopted as an index of exposure to automobile exhaust. The estimated odds ratios for chronic cough, chronic phlegm, chronic wheeze, shortness of breath, and chest cold with phlegm, relative to distance from the roadside--adjusted by age, smoking status, years at residence, occupation, and type of home heating-ranged from 0.76 to 2.75. The 95% confidence limits of the odds ratios for chronic cough and chronic phlegm excluded or approached 1.00 in each of the studies. This suggests that exposure to automobile exhaust may be associated with an increased risk of certain respiratory symptoms.

Adult↗

Respiratory health associated with exposure to automobile exhaust. III. Results of a cross-sectional study in 1987, and repeated pulmonary function tests from 1987 to 1990.

We conducted an epidemiological study to investigate the association between exposure to automobile exhaust and respiratory health. We selected 3 zones from two geographically different areas in Tokyo on the basis of expected exposure levels: (1) within 20 m from the side of major roads with heavy traffic, (2) between 20 and 150 m from the side of the same road, and (3) a residential district of suburban Tokyo. The subjects of the study were female adults aged 30-59 y. A cross-sectional study of respiratory symptoms and repeated pulmonary function testing were also performed in each zone. The results suggested that exposure to automobile exhaust may be associated with respiratory symptoms. Nevertheless, repeated pulmonary function testing did not reveal any consistent differences. Investigators should conduct additional follow-up studies to investigate the decline of pulmonary functions with age.

Adult↗

Relationship between dialysis induced hypotension and adenosine released by ischemic tissue.

Two types of dialysis induced hypotension apparently exist. One type presents as gradually decreasing blood pressure with eventual symptoms (gradual hypotension), whereas the other presents as abruptly and sharply decreasing blood pressure, along with symptoms (abrupt hypotension). In the current study, the authors found that the plasma hypoxanthine concentration during abrupt hypotension was significantly higher than before the hypotension occurred (20 min after saline was administered or at the beginning of dialysis), whereas comparison of the plasma hypoxanthine concentration during gradual hypotension and that before the hypotension occurred (20 min after saline was administered or at the beginning of dialysis) revealed no significant difference. The current results indicate that abnormally increased adenosine triphosphate (ATP) degradation associated with tissue ischemia occurred during abrupt hypotension but not during gradual hypotension. It can be speculated that the increased release of adenosine due to abnormally increased ATP degradation caused the abrupt hypotension. This conclusion seems reasonable given that adenosine directly decreases small vessel tone and inhibits prejunctional release of norepinephrine.

Adenosine↗

Ultrasonic homogenization of expressed human milk to prevent fat loss during tube feeding.

Effective use of expressed human milk in infant feeding requires proper handling, processing, storage, and administration in order to maintain its unique nutritional properties. One of the problems with expressed human milk is the separation of fat during processing, storage, and administration to the infant. Administration by continuous nasogastric infusion, either by intermittent gravity flow or by continuous mechanical pump, resulted in significant loss of fat and variation in the constitution of the milk delivered. Homogenization by ultrasonic treatment prevented changes in fat concentration during infusion and essentially eliminated loss of this nutrient during administration. The conditions necessary to achieve fat dispersion and stabilization of fat particles in human milk by ultrasonic treatment are described.

Animals↗

Spontaneous partial fracture of the catheter of a totally implantable subcutaneous infusion port.

A totally implantable subcutaneous infusion port was inserted via the left subclavian vein with peel-away sheath in a 45-year-old male patient receiving home parenteral nutrition. Sixteen months after implantation, the patient noted pain in his left clavicular region during home infusion. This was found to be due to the leakage of infusion fluid resulting from partial fracture of the catheter at the level where the catheter passed between the clavicle and first rib. Because the fracture was partial, the catheter did not embolize to the heart or large vessels. Although subcutaneous infusion ports afford patients greater freedom and the ability to lead a more active life than do external catheters, it is emphasized that there may be the risk of spontaneous catheter fracture in patients using subcutaneous infusion ports.

Catheters, Indwelling↗

Experimental study of hub contamination: effect of a new connection device: the I system.

Experimental studies of hub contamination of intravenous catheters were done comparing the standard connection method (Luer-Lock connector) with a newly invented connection method (I system). Immersion of the connection sites into a bacteria-containing solution showed no bacterial contamination of the medium in any tubing. The second experiment investigated whether bacterial contamination would occur during a tubing change procedure. A high incidence of bacterial contamination was seen with the Luer-Lock connector, but no bacterial contamination occurred with the I system. These experiments suggest that the use of Luer-Lock connectors is associated with a high risk of bacterial contamination during tubing change, but the I system can prevent contamination during tubing change, which cannot be avoided with Luer-Lock connector.

Bacteria↗

Prevention of catheter-related sepsis during parenteral nutrition: effect of a new connection device.

A prospective study was carried out to determine the clinical effect of a newly devised catheter connection method (I system) and piggyback access system. Previous studies have demonstrated that the I system avoided bacterial contamination in vitro during tubing change that Luer-Lock connectors did not. The purpose of this study was to investigate the ability of this device coupled with a new closed-system piggyback technique for multipurpose access to reduce catheter-related sepsis in clinical practice. Two hundred and thirty patients receiving total parenteral nutrition were divided into two groups. Group I (n = 106) used the I system connector and group L (n = 124) used a Luer-Lock connector. Catheters in both groups were used for multipurpose access for infusion and blood sampling. In group L, a three-way stopcock and/or pig-gyback system was used for multiple access. In group I, a newly designed closed-system piggyback was used. The incidence of catheter-related sepsis was significantly lower in group I (1.89%/catheter) than in group L (12.10%/catheter) (p < .01, chi 2 analysis), and the average duration of use of each catheter was significantly longer in group I than in Group L (p < .01 by generalized Wilcoxon test). The results of this clinical study suggest that the newly designed connection method and piggyback access system are able to reduce catheter-related sepsis.

Adolescent↗

Induction of the renal pelvic and ureteral carcinomas by N-butyl-N-(4-hydroxybutyl)nitrosamine in SD/cShi rats with spontaneous hydronephrosis.

We attempted to establish an animal model for renal pelvic and ureteral carcinomas. In Experiment 1, Sprague-Dawley (SD)/cShi and SD/gShi strains of male and female rats and Fischer-344 (F-344)/DuCrj and LEW/Crj strains of male rats, 6 wk old, were given 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 12 wk and then treated without chemical for 10 wk. Only the SD/cShi strain, which has spontaneous hydronephrosis and hydroureter, showed high incidences of carcinomas in the renal pelvises and ureters, whereas the other strains did not. In Experiment 2, SD/cShi and Crj:CD strains of male and female rats, 6 wk old, were exposed to 0.05% BBN for 20 wk. Both sexes of SD/cShi rats had high incidences of bilateral carcinomas in renal pelvises and/or ureters associated with urinary bladder carcinomas, whereas both sexes of Crj:CD rats had urinary bladder tumors only. These results indicate that the SD/cShi strain may be a suitable animal for the induction of renal pelvic and ureteral carcinomas that appear to depend on urine stagnation secondary to hydronephrosis and hydroureter.

Animals↗