TASK DEFINITION: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
PROBLEM: Abstract: The distribution of whole-body O2 supply during severe hypoxia and recovery and its relation to the regional distribution of O2 deficit and repayment was studied. Mongrel dogs were anesthetized, paralyzed, and ventilated to maintain an end-tidal PCO2 between 35 and 40 Torr. In one group, the alpha- and beta-adrenergic receptors were blocked to eliminate neural and humoral adrenergic influences. In a second group, alpha-adrenergic receptors were stimulated to decrease O2 delivery by excessive vasoconstriction. In a third group, beta-adrenergic receptors were stimulated to increase O2 delivery. Whole-body and hindlimb muscle O2 uptake and vascular responses were measured during normoxic control, 15 or 30 min of severe hypoxia (9% O2 in N2), and 20 or 30 min of normoxic recovery, respectively. The whole-body O2 deficit and excess O2 uptake in recovery were partitioned into muscle and nonmuscle areas. The data showed that neural or humoral influences had little effect on the regional distribution of the total O2 deficit and O2 excess in recovery. The O2 deficit could be decreased somewhat by increasing delivery, but the amount of excess O2 used in recovery was unaffected. This suggested that the excess O2 use in recovery was more a function of an energy deficit during hypoxia and not an O2 deficit.

SOLUTION: Animal

PROBLEM: Abstract: Anestrous hamsters exhibit daily afternoon gonadotropin and progesterone surges, but little estrogen secretion. In the first experiment, short day anestrous females were transferred to long days to detect hormonal changes associated with recovery of cyclicity. Morning and afternoon blood samples were taken at increasing durations in long days. Females autopsied at their first vaginal estrus after transfer to long days differed from long day estrous controls only in their lower uterine weights. Some females at all durations exhibited signs of recovery, though they had not yet shown estrus. They did not display afternoon gonadotropin surges and had low circulating progesterone but high estradiol levels, stimulated uteri, and enhanced follicular development. Results of the second and third experiments provided evidence that the daily gonadotropin surges are not the cause per se of anestrus, and that changes in estrogen secretion are essential for the transition to and from anestrus. Phenobarbital blockade of the daily surges in anestrous females did not result in increased follicular growth and estrogen secretion. Furthermore, daily afternoon injections of gonadotropins it appears that the daily surges in anestrous hamsters simply reflect low estradiol levels. It is still not known what signal promotes rapid follicular maturation during the recovery from anestrus. Once initiated, however, this recovery appears to occur within a few days, with a rapid cascade of events. First, follicular development and estrogen secretion resume, and the daily LH surges cease. Then, progesterone levels decline, and an ovulatory surge of gonadotropins is triggered.

SOLUTION: Anestrus

PROBLEM: Abstract: Physiological concentrations of L-T4 were found previously to stimulate Ca2+-ATPase activity in vitro in reticulocyte membranes from female rabbits and to inhibit this enzyme in reticulocyte membranes from males. In these previous studies, preincubation of intact cells or ghosts with testosterone (5 X 10(-11) M) converted female-source reticulocyte membranes to male-type responsiveness to thyroid hormone (inhibition of Ca2+-ATPase activity). Preincubation of reticulocyte membranes with 17 beta-estradiol (5 X 10(-11) M) converted male-source membranes to female-type responsiveness (stimulation by L-T4 of membrane Ca2+-ATPase activity). Using this sex steroid-sensitive thyroid hormone-dependent membrane enzyme system, we investigated the structure-activity relationships of analogs of sex steroids and unrelated steroids. 5 beta-Androstanes were active compared to testosterone in assays using female-source membranes, while 5 alpha-androstanes were less active. Within the 5 beta-androstanes, activity was dependent on at least one hydroxyl group at the C3- or C17-position. Nongonadal steroids tested were less active, establishing specificity of the sex steroid effect in assays using female-source membranes. Assayed in male-source membranes, estrone and 3-hydroxy-1,3,5-(10)7-estratraen-17-one (equilin) were active compared for estrogen effect with 17 beta-estradiol, while estriol was less active. The activities of hydrocortisone and aldosterone were 76% and 71%, respectively, in this system. These structure-activity relationships are distinct from those described for gonadal steroid-cytoplasmic binding proteins or nuclear interactions, and represent a novel sex steroid-thyroid hormone effect on activity of a membrane enzyme.

SOLUTION:
Adenosine Triphosphatase, Calcium