Oxygen consumption and ventilation during simulated escape from an offshore oil platform.

Twenty-six male workers from the North Sea offshore oil industry took part in a simulated escape exercise at the Offshore Fire Training Centre. The course was 370 m long and had 19.4 m of vertical ascent and descent using the stairs on simulated offshore structures. Inspired ventilation and oxygen consumption were measured using the P. K. Morgan "Oxylog' and subjects breathed through the apparatus by mouthpiece and one-way valve assembly while wearing a nose clip. On comparison with anthropometric data from larger studies, this sample of the offshore work-force was thought to be representative. The mean duration of the exercise period was 371 s (SD = 24 s, range = 325-424 s). Mean oxygen consumption standing still at the start of the trial was 0.421 min-1 (SD = 0.101 min-1, max. = 0.611 min-1) and mean ventilation 12.351 min-1 (SD = 4.251 min-1, max. = 22.271 min-1). During exercise, the mean oxygen consumption rose to 2.711 min-1 (SD = 0.641 min-1, max = 4.051 min-1) and mean ventilation reached 46.341 min-1 (SD = 15.831 min-1, max = 87.361 min-1) during the fifth minute of exercise. At the end of the exercise period, oxygen consumption returned to resting values after 2 min and ventilation after 3 min. There was no indication of an oxygen debt. Oxygen consumption and ventilation were related to body weight and the maximum figures for ventilation and oxygen consumption were seen in individuals of over the 95th centile for weight who completed the exercise more quickly than other subjects. Draft standards for respiratory protective equipment for use during escape from fire do not specify the breathing volumes identified in this study, and which are considerably higher than those being currently considered. Additionally, the atmospheric conditions near a fire are likely to stimulate ventilation to considerably higher levels than those identified here. Accordingly, such equipment is likely to limit physical performance if a similar intensity of exercise is necessary during an escape. The architecture of offshore installations and protocols for escape from them should be structured to minimize exercise, and stair climbing should be avoided if emergency respirators are to be used. Workers should be trained in the use of escape breathing equipment and instruction should include information regarding its limitations and the need to limit exercise to an appropriate level.

Ventilation and oxygen uptake during escape from a civil aircraft.

To help develop a specification for equipment providing personal respiratory protection in the event of aircraft fire a study was carried out to quantify ventilation and oxygen consumption during escape from a Trident aircraft. Data were gathered using the P.K. Morgan 'Oxylog' apparatus after its response time to rapid changes in inspired to expired oxygen concentration difference was assessed using a bench test. The 'Oxylog' had a lag time of 30-32 s and a 5-95% response typified by a half time of 20 s. The data gathered were corrected in the light of these findings. Fourteen male subjects aged 17-38 years were studied under two conditions. Four mass evacuations each involving 40 people; a total of nine subjects escaping from the front rank over eight seats being monitored. Six evacuations each involving only two people escaping from the rear of the cabin; a total of 11 subjects escaping over 14 seats being monitored. Escape was made over the seat backs, down an escape chute to a position 12 m from the base of the chute. Resting minute ventilation (mean 16.7 1 STPD) and oxygen consumption (mean 0.41 min-1 STPD) were similar before both evacuations. There were no significant differences between the two conditions either during, or up to 180 s after escape. Ventilation and oxygen consumption were greatest in the recovery period. The highest oxygen consumption seen was 2.08 l min-1 and maximum minute ventilation was 641. Mean total oxygen consumption for the escape and a 150 s recovery period was 2.41 l (s.d. 0.64, max. 3.11) for the mass evacuation and 2.97 l (s.d. 0.68, max. 4.09) for the two person evacuation. The mean total amount of gas inhaled during the same time period was 89.3 l (s.d. 25.6, max. 121.3) for the mass evacuation and 99.01 (s.d. 26.2, max. 137.3) for the other. These was no correlation between ventilation or oxygen consumption and either escape time, body weight, height or age.

Biochemical studies of N-methyltransferase in human and guinea-pig lung: no apparent role in the pathogenesis of asthma.

1. N-Methyltransferase activity was measured in surgical specimens of human lung using phenylethanolamine as substrate. Thirty-three male and seven female patients, age range 19-78 (median 62.5) years were studied. The activity in lung homogenates was 0.59 x 10(-6) units/mg of protein (SEM 0.03, n = 40), with a range of 0.16-1.16 x 10(-6) units/mg of protein. There was no difference (P = 0.97) in activity between males and females. 2. Non-specific N-methyltransferase activity was estimated in 17 of the surgical specimens using beta-phenylethylamine as substrate. This activity was 38.9% (SEM 5.3) of that with phenylethanolamine. Comparative studies with rabbit lung, which has a well-characterized non-specific N-methyltransferase, showed significant differences in substrate specificity between the two species. 3. The apparent Km and Vmax for phenylethanolamine in seven human lung homogenates was 22.0 (SEM 4.6).mmol/l and 1.82 x 10(-6) units/mg of protein (SEM 0.36). The noradrenaline N-methyltransferase (NMT; EC 2.1.1.28) inhibitors SKF 64139-A and LY 134046 did not inhibit this activity up to a concentration of 100 mumol/l. This activity was inhibited 51.4% (SEM 8.6, n = 6) by 100 mumol/l S-adenosyl-L-homocysteine. Immunohistochemistry did not reveal immunoreactive NMT in human lung sections. 4. Comparative studies with guinea-pig lung homogenates demonstrated non-specific N-methyltransferase activity in this species which is similar to the human lung.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of undernutrition of beef cows on blood hormone and metabolite concentrations post partum.

Twelve Hereford Friesian cows were allocated to either a high plane (HP) or a low plane of nutrition (LP) post-partum. HP animals received rations supplying sufficient energy and protein for maintenance plus 10 kg/day milk yield. LP cows were offered approximately 70% of their maintenance needs for 63 days post-partum. Thereafter they received the same ration as the HP animals. A mineral vitamin supplement was included in all concentrates fed. Calves were only permitted to suckle twice daily and all animals were weighed once weekly. Blood samples were taken once daily and the levels of serum progesterone, luteinizing hormone (LH) and prolactin (PRL) estimated. Once weekly blood samples and diurnal samples (once fortnightly) were measured for their content of insulin, non esterified fatty acids (NEFA), glucose, total protein, albumin and urea. Oestrus was detected by visual observation and by intra vaginal electrical resistivity and ovulation was confirmed by rectal palpation. After 110 days all animals were synchronized with two injections of prostaglandin. This was followed by fixed time insemination at 72 and 96 hours. Time from parturition to first ovulation was: HP; 39 +/- 8.7 days; LP, 65,3 +/- 33,2 days. All HP animals showed regular cyclic ovarian activity whereas only 3 of the LP cows were normal (LPR). The ovarian activity of the remaining LP cows (LPI) was almost completely suppressed. Of the animals that cycled normally there was no difference in progesterone concentrations between treatments. Average LH concentrations did not differ between HP and LP or between LPR and LPI cows. HP cows maintained their body weight post-partum whilst the LP lost 21.4 +/- 4.40% by day 63. Milk yield of the LPI animals was consistently higher than that of the LPR and it was found that the nine regularly cyclic animals had a lower milk yield to body weight ratio than those that failed to cycle properly (P less than 0.05). Differences between the HP and LP cows were found in relation to insulin, PRL, glucose, NEFA, urea and albumin concentrations. No variation in these parameters was observed that could explain the divergence in ovarian activity of the LPR and LPI groups.

Carnitine and creatine content of tissues of normal and alloxan-diabetic sheep and rats.

The concentration of carnitine in liver increased 28-fold and urinary carnitine excretion 5-fold in alloxan-diabetic sheep. In contrast there were no similar increases in alloxan-diabetic rats. The creatine content of liver decreased 3-fold and creatine excretion decreased 2-fold in diabetic sheep. In contrast the creatine content of liver increased nearly 4-fold in diabetic rats with no change in creatine excretion. The marked increased in production of carnitine by the liver of the diabetic sheep appears possible because of decreased production and excretion of creatine.

Studies of liver lipids in normal, alloxan-diabetic and pregnancy-toxaemic sheep.

Triacylglycerols were the major lipid class in the fatty livers from alloxan-diabetic sheep and those suffering from pregnancy toxaemia, with the concentrations increased by 15- and 25-fold, respectively, compared with the normal state. Analysis of the fatty acid composition of total liver triacylglycerols in these animals showed a significant decrease in the proportion of saturated fatty acids, 16:0 and 18:0, and increase in the proportion of polyunsaturated fatty acids (18:2 omega 6, 18:3 omega 3 and 20:4 omega 6), particularly in those with pregnancy toxaemia. In contrast, total liver phospholipids showed a significant increase in the proportion of 18:0 in ewes with pregnancy toxaemia and a significant decrease in a range of polyunsaturated fatty acids in both the diabetic and toxaemic animals. Also, although the concentration of both phosphatidylcholine and phosphatidylethanolamine increased in the diabetic livers the ratio of phosphatidylcholine/phosphatidylethanolamine fell significantly, from 2.22 in the control animals to 1.59. The data suggest that, following the large influx of plasma fatty acids into the ovine liver in diabetes and pregnancy toxaemia, there is a diversion of polyunsaturated fatty acids from phospholipids to triacylglycerols. In diabetic sheep these changes may in turn affect phosphatidylcholine synthesis via the methylation pathway in liver. These changes in lipid composition may, in part, explain the degenerative changes in membrane and subcellular organelle structure and the failure of liver function observed both in advanced diabetes and in severe pregnancy toxaemia.

Laparoscopy in Southland.

A review was made of 625 consecutive gynaecological laparoscopies carried out in the Southland Hospital. Forty-one point seven percent were for diagnostic reasons, mainly in the diagnosis of pelvic pain and infertility, and 57.3 percent were for sterilisation. Complications occurred with 2.2 percent and 5.6 percent respectively, but the serious complications and those requiring laparotomy only came to 1.1 percent. Four women (1.1 percent) became pregnant after sterilisation, all four occurring during the first year of the procedure. Overall, laparoscopy is confirmed to be a valuable diagnostic technique and a safe method of sterilisation.

PIP: A retrospective review of 625 consecutive laparoscopies performed in Southland Hospital from 2/74 to 10/78 revealed that 41.7% (262) were carried out for diagnostic purposes (pelvic pain and infertility), 57.3% (357) for sterilization, and 1% (6) for a combination of both. Complications rate for each were observed in 2.2% and 5.6% respectively; 1.1% had serious complications and required laparotomy. Complication rate for each year decreased since the beginning of the study (from 6.7% in 1974 to 2.2% in 1978). The introduction of laparoscopic sterilization in 1975 resulted in an increase in number of sterilizations (from 142 in 1974 to 310 in 1975). 1/3 of the total sterilizations each year consisted of laparoscopic sterilization; abdominal tubal ligation, and postpartum tubal ligation. Of the sterilizations 97.2% (353) were interval procedures, 2.2% (8) were done at the time of termination of pregnancy, and .6% (2) were after spontaneous abortion. Because of lower complication rates associated with laparoscopy; shorter hospital stay; and rapid recovery, it was concluded that laparoscopic sterilization is a valuable diagnostic technique and a safe method of sterilization.

Aspects of carnitine ester metabolism in sheep liver.

1. Carnitine acetyltransferase (EC 2.3.1.7) activity in sheep liver mitochondria was 76nmol/min per mg of protein, in contrast with 1.7 for rat liver mitochondria. The activity in bovine liver mitochondria was comparable with that of sheep liver mitochondria. Carnitine palmitoyltransferase activity was the same in both sheep and rat liver mitochondria. 2. The [free carnitine]/[acetylcarnitine] ratio in sheep liver ranged from 6:1 for animals fed ad libitum on lucerne to approx. 1:1 for animals grazed on open pastures. This change in ratio appeared to reflect the ratio of propionic acid to acetic acid produced in the rumen of the sheep under the two dietary conditions. 3. In sheep starved for 7 days the [free carnitine]/[acetylcarnitine] ratio in the liver was 0.46:1. The increase in acetylcarnitine on starvation was not at the expense of free carnitine, as the amounts of free carnitine and total acid-soluble carnitine rose approximately fivefold on starvation. An even more dramatic increase in total acid-soluble carnitine of the liver was seen in an alloxan-diabetic sheep. 4. The [free CoA]/[acetyl-CoA] ratio in the liver ranged from 1:1 in the sheep fed on lucerne to 0.34:1 for animals starved for 7 days. 5. The importance of carnitine acetyltransferase in sheep liver and its role in relieving ;acetyl pressure' on the CoA system is discussed.