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.

Input: Consider Input: Abstract: The role of the second messengers cAMP and Ca++ in the control of proopiomelanocortin (POMC) gene expression was investigated with the use of hybridization with cloned complementary DNA probes. The effects of cAMP-related drugs on POMC messenger RNA (mRNA) levels were assessed in primary cultures of intermediate (IL) and anterior rat pituitary cells maintained in serum-free medium. 8-Bromo-cAMP (1 mM), but not 8-bromo-cGMP (1 mM), induced a 2-fold increase in IL and anterior lobe cell after 2 days of treatment. A similar increase was obtained with the adenylate cyclase-activating drugs forskolin (1 microM) and cholera toxin (100 ng/ml) or the phosphodiesterase inhibitor RO 20-1724 (100 microM). At 48 h, all these treatments had increased beta-endorphin accumulation in the medium and transiently decreased the cellular beta-endorphin content in IL cells, suggesting a parallel effect of cAMP-related drugs on secretion and biosynthesis. Incubating the cells with the Ca++ channel antagonists D600 (50 microM), verapamil (50 microM), and the dihydropyridine nifedipine (0.1 microM) decreased basal POMC mRNA levels, whereas the dihydropyridine BAYK 8644 (0.1 microM), which activates the Ca++ channel, increased POMC mRNA levels after 2 days. In addition, nifedipine decreased the stimulatory effect of forskolin, whereas BAYK 8644 further stimulated the forskolin-increased POMC mRNA levels in IL cells. We conclude that both Ca++ and cAMP may regulate the gene expression of POMC.

Output: Adenosine Cyclic Monophosphate

Input: Consider Input: Abstract: Histamine released from skin mast cells in normal skin sites of patients with idiopathic chronic urticaria (CU) and normal volunteers was assessed with the skin chamber technique. Small amounts of histamine were spontaneously and continuously released during the 4-hour observation in both groups but were twofold greater in patients with CU. In addition, histamine levels were significantly more elevated in sites challenged with compound 48/80 than in unstimulated sites. Patients with CU differed from normal volunteers in that histamine release induced by 48/80 compound was significantly greater at 1 and 2 hours after challenge. The number of mast cells and the histamine content of the skin did not differ in the two groups. These observations could suggest a functional defect at the mast cell level rather than a difference in their numbers.

Output: Adolescence

Input: Consider Input: Abstract: We have tested the hypothesis that there is a positive relation between arterial elasticity and physical working capacity (PWC) at a given age. The subjects were 28 young men, 16-18 yr old. Arterial elasticity was evaluated by measuring the carotid to femoral pulse-wave velocity (c) at rest. The slope, S(c) of the relation between c and the diastolic blood pressure was studied during a cold pressor test to test vascular reactivity. The relationship between heart rate (HR) and work load was determined using a cycle ergometer; the variables measured were the slope of this relation S(PWC) and the power output at a HR of 170 min-1 (PWC170). The PWC170 ranged from 1.8 to 4.6 W/kg, and values of c ranged from 3.9 to 6.8 m/s. A strong inverse linear relation was found between c and PWC170 (r = -0.76), whereas the HR at rest was positively related to both c (r = 0.68) and PWC170 (r = 0.74). There was no relationship between HR at rest and the slopes S(c) and S(PWC); the latter two variables depend mainly on the sympathetic response. These results show the importance of the intrinsic mechanical properties of the cardiovascular system, particularly arterial elasticity, in human adaptations to muscular exercise.
Output: Adolescence