We compared the effects of glucagon infused at 5 and 50 ng X kg-1 X min-1 on glucose turnover (GT), production (Ra), and utilization (Rd) in the fetal (F; n = 5, gestation 129 +/- 3 days, term approximately 150 days) and nonpregnant adult (A; n = 5 and 6) sheep. Infusion of glucagon at 5 ng X kg-1 X min-1 raised fetal glucagon levels (IRG) from a basal of 168 +/- 27 to a mean sustained level of 863 +/- 160 pg/ml but had no effect on basal levels of glucose (G) of 12 +/- 3 mg/dl, insulin (IRI) of 16 +/- 3 microU/ml, GT of 21 +/- 1.3 mg/min, and Rd of 15 +/- 2 mg/min; Ra remained negligible. When fetal IRG was raised to a mean sustained level of 1,809 +/- 210 pg/ml by infusion of glucagon at 50 ng X kg-1 X min-1, G doubled to 23 +/- 1.5 mg/dl, IRI rose to 21 +/- 0.9 microU/ml, GT rose to 60 +/- 5 mg/min, Rd to 30 +/- 4.8 mg/min, and Ra to 41 +/- 6 mg/min (P less than 0.01 for each) indicating induction of F glucose production so that GT was now derived from endogenous sources. By contrast, when IRG levels were raised from 109 +/- 10 to 538 +/- 43 pg/ml by infusion of 5 ng X kg-1 X min-1 to A, basal G rose from 56 +/- 2 to 88 +/- 6 mg/dl, IRI from 24 +/- 2 to 45 +/- 6 microU/ml, GT and Ra from 93 +/- 7 to 173 +/- 17 mg/min, and Rd from 93 +/- 7 to 148 +/- 12 mg/min (P less than 0.01 for each). No further increments of these indexes occurred in A when IRG was raised to a mean sustained level of 2,275 +/- 135 pg/ml by infusion of 50 ng X kg-1 X min-1. These results indicate a relative resistance in F to the glycemic effects of glucagon, consistent with previously demonstrated decreases of hepatic glucagon receptors and glucagon-stimulated cAMP production in fetal liver.

No abstract

We investigated the effects of a 3-mo submarine patrol upon several vitamin B-6 indices in 23 male submariners. While on patrol, 12 subjects received a multivitamin-mineral supplement that provided 0.5 mg/d vitamin B-6 and 11 subjects received a placebo. The concentrations of plasma pyridoxal 5'-phosphate, total vitamin B-6, and urine 4-pyridoxic acid were significantly reduced during the patrol in both the placebo and the supplemented groups. The hematocrit of both groups also decreased by approximately 10% during the patrol and was not restored to prepatrol concentrations until several weeks postpatrol. Mood depressions, as measured by the Beck inventory and the depression adjective check list, were most pronounced during the 30 d before and at the beginning of the patrol. These depression measures did not correlate with the vitamin B-6 status indices, indicating that the mood depressions during a patrol do not appear to be related to the vitamin B-6 status of the submariners.

No abstract

The responses of 100 Navy sonar operators were compared to those of over 600 Navy recruits using the Hidden Patterns, Gestalt Completion, and Cube Comparison tests. Sonar operators attempted more items and made fewer errors on Hidden Patterns, attempted more items on Gestalt Completion, and made fewer errors on Cube Comparison than recruits, while recruits attempted more Cube Comparison items than sonar operators. The two groups did not differ in Gestalt Completion errors. These measures, especially Cube Comparison, may be useful in screening Navy personnel for sonar training, particularly training for those sonar systems in which visual displays are used extensively.