Effects of long-term injection of steroid hormone on soluble protein in rat muscles and organellae.

Steroid hormone (dexamethasone, 0.1 mg/kg/day) was injected into Wistar strain rats, and its effect on the weight of organellae and skeletal muscles was studied. Steroid was injected for 20, 30 and 40 weeks, and a de-steroid group was obtained by interrupting the steroid injections for three weeks. The body weight of the injected rats decreased by 40 to 60% from that of the control, even when food intake per body weight was increased by more than 20%. The weight of organellae (heart, liver and adrenal glands) apparently decreased. Nevertheless, the weight per body weight tended to recover to the control level in the de-steroid group. Muscle atrophy of the proximal muscles, the rectus femoris and the semimembranosus muscles was observed in the steroid group. Remarkable atrophy appeared in the semimembranosus muscle, named type II fiber, with 40% to 60% of control at the 30th and 40th weeks and the recovery rate of this weight was determined in only 80% in the de-steroid group. A decrease of the 40,000 to 60,000 MW polypeptides of serum and muscle soluble protein fraction was shown in the 40-week group. These results suggested that acceleration of glycolysis, glyconeogenesis and protein catabolism were induced after long-term steroid injection.

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.