PubMed Health⌕ Search

Biomedical subjects

C Sekiguchi

Publications and source records attributed to C Sekiguchi.

47 records · Page 3Linked to original sources
PubMed1987

Inflammatory responses in cuff-induced atherosclerosis in rabbits.

Cuff-treatment of the rabbit carotid artery produced a diffuse intimal thickening which resembled early lesions of atherosclerosis. A limited amount of focal endothelial damage occurred first (0.5 h), leukocytes infiltrated the subendothelium and extensive endothelial denudation occurred at 24 h. At 3 days, the regenerating endothelium covered the denuded area, and the media was edematous. At 7 days proliferation of intimal cells became visible. Maximum intimal thickening occurred at 3 weeks. Daily injection of dexamethasone (0.01-10 mg/kg i.m.) and ticlopidine (1-100 mg/kg i.m.) dose-dependently attenuated the intimal thickening. Indomethacin had little effect. Inflammatory exudate from zymosan-activated air pouch induced chemotaxis of rat smooth muscle cells (SMC) in vitro. Similar chemotactic activity was observed with leukotriene B4 (LTB4) but not with the other lipoxygenase products tested. The exudate contained reasonable amounts of LTB4, which would account for its chemotactic activity. Dexamethasone inhibited the chemotaxis by the exudate and proliferation of SMC. These results are discussed in relation to the mechanism of atherogenesis. It is concluded that leukocytes play a major role in cuff-induced intimal thickening, and that their products cause endothelial denudation and SMC chemotaxis. Involvement of platelet aggregation in atherogenesis is also suggested.

Animals↗
PubMed1987

Antiatherogenic activity of FR34235 (Nilvadipine), a new potent calcium antagonist. Effect on cuff-induced intimal thickening of rabbit carotid artery.

The antiatherogenic activity of FR34235 (Nilvadipine), a calcium antagonist, was examined in rabbits with carotid arteries sheathed with polyethylene cuffs, and compared with that of nifedipine, verapamil and diltiazem. The drugs were given intramuscularly in daily doses of 0.01-10 mg/kg for 3 weeks, starting on the day of cuff-placement. FR34235 dose-dependently inhibited the cuff-induced intimal thickening, and was more potent than the other calcium antagonists, whose order of potency was nifedipine, diltiazem and verapamil. In an in vitro experiment on inhibition of migration of rat aortic smooth muscle cells, using zymosan-activated air pouch exudate as a chemoattractant in modified Boyden chambers, FR34235 was also the most potent among the calcium antagonists tested. The IC50 values were 3.3 X 10(-11) M for FR34235, 1.7 X 10(-10) M for nifedipine, 6.0 X 10(-9) M for verapamil and 2.4 X 10(-7) M for diltiazem. Effects of these drugs on proliferation of rat aortic smooth muscle cells and rabbit platelet aggregation were also examined in vitro. At concentrations less than 10(-5) M, none of the drugs inhibited proliferation of the smooth muscle cells, and only verapamil inhibited collagen-induced platelet aggregation (IC50 = 9.0 X 10(-7) M). It is suggested that FR34235 should be useful for preventing and treating atherosclerosis. Inhibition of smooth muscle cell migration is thought to be its mechanism of antiatherogenic activity.

Animals↗
PubMed1986

Anti-G training of Japanese Air Self Defense Force fighter pilots.

Recently developed high-performance fighter aircraft (HPF) are capable of producing high sustained +Gz (HSG) with a rapid onset rate. This G-producing capability is now beyond human physiologic G tolerance. Many techniques to raise the tolerance to HSG have been used operationally. In order to cope with HSG effectively, the Japanese Air Self Defense Force has given high-G training for certain fighter pilots since 1982. So far, 138 pilots (62 F-15 Trainees, 76 F-4 Trainees) have completed centrifuge training at our laboratory. The 1-week program consists of: physical examination and briefing on high-G stress and its protective methods on day 1; centrifuge rides in two basic patterns--a tracking performance and a simulated aerial combat maneuver (SACM)--during the period from day 2-5; and debriefing and questionnaires on day 6. Gradual onset run (GOR) relaxed tolerance is + 5.5 +/- 0.7 Gz and rapid onset run (ROR) relaxed tolerance is + 4.9 +/- 0.6 Gz (n = 126). The difference in G tolerance between F-15 and F-4 trainees was not significant in either GOR or ROR. Loss of consciousness (LOC) occurred in 18 F-15 trainees and 15 F-4 trainees during basic patterns but all F-15 trainees met the training goal and completed the SACM pattern on day 5 without LOC. More than half of the trainees developed a variety of arrhythmias, including PVC, SVPC, A-V dissociation, S-A block, and atrial fibrillation (AF). The AF case developed WPW syndrome and atrial fibrillation followed by LOC during a 4-G warm-up pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

Acceleration↗
PubMed1982

Effects of relative metabolic rate and heart rate variation on the performance of flight attendants.

The main work of the cabin attendants in an actual flight in service for passengers. The effects of flight attendant duties in flight differ from the effects of the same tasks performed on the ground. In this study, the relative metabolic rate (RMR) and heart rate (HR) of cabin attendants in a cruising aircraft galley and cabin are compared with those of a crew working in a mock-up apparatus on the ground. The types of work tested are: (a) oshibori (steamed towel) service, (b) soft drink service, (c) setting meal tray, (d) putting casserole on tray, (e) meal tray service, (f) walking on aisle. The RMR at each type of work during flight is as indicated: (a) 1.07-2.10, (b) 1.08-1.54, (c) 1.37-1.82, (d) 2.57-3.50, (e) 2.11-3.10 and (f) 1.84. The range of HR was: (a) 105-120, (b) 90-110, (c) 90-120, (d) 100-130 and 100-140 beats/min. In most cases, the RMR and HR levels of work done in the mock-up were lower than those recorded in flight. These results suggest that the oxygen intake of work done in flight is greater than that on a mock-up. One of the reasons might be that the cabin barometric pressure (ca. 660 torr or cabin altitude ca. 1,500 m) or an aisle inclination of about 3 degrees caused a decrease in the efficiency of oxygen intake during flight.

Adult↗
PubMed1979

Frequency analysis of heart rate variability under flight conditions.

The factors causing heart rate variability (HRV) were investigated under various kinds of workloads and flight conditions. Frequency analysis of heart rate, and cross-correlation analysis with blood pressure and respiration, were performed by using the fast Fourier analyser. Consequently, the main frequency of HRV at rest consisted of 0.1 Hz and 0.25-0.3 Hz. These fluctuations disappeared under physical loads, but the value of 0.1 Hz at first increased under moderate mental load and thereafter decreased as the mental load increased. It was suggested that the behavior of the frequency 0.1 Hz under mental load was influenced partly by higher brain centers. For the actual flight, the frequency decreased under takeoff and landing, and remained as at rest during the gunnery and acrobatic training flight. It was concluded that the evaluation of workloads under flight conditions by using the analysis of the factors of HRV was very useful to improve a man-machine interface.

Acceleration↗
PubMed1978

Evaluation method of mental workload under flight conditions.

In order to analyze the relationship between heart rate variability (HRV) and the flight tasks of pilots, HRV of various mental and physical work stresses were investigated. For the physical stress on the treadmill, S.D. of heart rate sequence showed a minimum value at medium stresses and remained there until the maximum stress. However, the centrifuge acceleration test presupposed special physical stresses, and S.D. was almost same as the resting findings. In the tracking tasks, which presupposed maximum interpretative actions, the increase in the mean heart rate (MHR) was small with the S.D. increased a greater amount than for resting results. Consequently, preflight checks and level flight phases presupposed medium interpretative actions and mental stress with reserve capacity. Takeoff and landing phases were considered as both high interpretative action and high emotional stress situations. Acrobatic and gunnery training flight phases were considered physical load, strong interpretative actions, and emotional stress tasks.

Acceleration↗
PubMed1977

Continuous ECG monitoring on civil air crews during flight operations.

Cardiovascular disease is one of the disorders resulting in sudden incapacitation and is the most common malady leading to medical retirement. It is very important for us to control this disease among pilots. Generally, pilots undergo medical checkups at health control service on the ground, but they do not undergo these checkups during flight operations. We obtained a continuous ECG recording on four pilots to assess cardiac reserve capacity for mental load during flight operation. Results show that no significant ischemic changes of ST-segment and T-wave during flight were noticed except in one case of atrial fibrillation in which significant depression of ST-segment occurred while walking up a stairway after flight. An increased number of ectopic beats was found in another normal case. In general, it was suspected that mental load is greater at landing than takeoff.

Accidents, Aviation↗
PubMedDate not supplied

Effects of 10 min tilt and visual directional information on ocular counterrolling.

The effects of 10 min of static tilt on ocular counterrolling (OCR) were investigated. Seven healthy volunteers were tilted 45 degrees around the naso-occipital axis, fixed at that position for 10 min, and the pre- and post-tilt OCRs were recorded. OCR was video-recorded using an infrared CCD camera and subjected to computer image analysis. The subjects were directed to fixate on an imagined target in the dark (experiment 1), or viewed an earth vertical, striped pattern placed in front of his/her eyes to enhance the recognition of extent of body tilt (experiment 2). In experiment 1, the average OCRs recorded before and after 10 min of tilt showed no significant changes. However, in experiment 2, OCR decreased significantly after 10 min of tilt. These results suggest that visual perception of spatial verticality can produce time-dependent adaptation of OCR.

Adaptation, Ocular↗
PubMedDate not supplied

Pancreas-sparing duodenectomy: classification, indication and procedures.

BACKGROUND/AIMS: Recent advances in the surgical anatomy of the pancreatoduodenal region have permitted duodenum-preserving pancreatic head resection. However, pancreas-sparing duodenectomy (PSD) has not been systematically studied and various types of such procedures have been reported under the designation of PSD. METHODOLOGY: PSD was performed in 6 patients with extensive duodenal lesions including trauma, mucosa-associated lymphoid tissue (MALT) lymphoma, corrosive necrosis, bleeding, leiomyosarcoma and congenital stenosis. Three patients had the whole papilla Vateri and half of the duodenum preserved and anastomosed to the jejunum. One patient had the duodenal button including the papilla of Vater transplanted to the jejunum. Another patient had the intraduodenal portion of the major papilla excised and the terminal portion of the bile and pancreatic ducts anastomosed to the jejunum. RESULTS: Two patients with moribund conditions died of the underlying disorders 2 weeks and 3 months after surgery, respectively, but without leakage or other surgery-associated complications. The other 4 patients survived the surgery without anastomotic insufficiency. Three survivors, who had complete preservation of the major and minor papillae along with the half portion of the duodenum, had normal morphology and function of the biliopancreatic system post-operatively. The fourth survivor, that with excision of the intrapancreatic portion of the major papilla, had regurgitation of contrast material into the bile and pancreatic ducts 2 months after surgery on active insufflation of the intestinal lumen, but remained asymptomatic. No abnormality in liver and pancreatic function was detected as of 7 months post-operatively. CONCLUSIONS: PSD appears to be applicable in the clinical setting, although classification of the procedure seems mandatory in consideration of indications, techniques, and long-term consequences of biliopancreatic function.

Adult↗