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.

Abstract: Statistically significant linear correlations between geographic variations in salt consumption and mortality from gastric, but not duodenal ulcer, are reported. It is suggested that dietary consumption of salt is a risk factor in mortality from gastric ulcer.
Aged

Abstract: Bed-rest deconditioning is suspected to reduce cardiac reserve, possibly by impairing autonomic function. Heart rate response in normal subjects reveals considerable variability, reflected by a relatively broadband interbeat interval power spectrum. A reduction in this autonomically modulated variability would be predicted to cause a narrowing of the spectrum. We retrospectively analyzed data from 10 aerobically conditioned men (age range 35-49 yr) who had undergone orthostatic tolerance testing with lower body negative pressure pre-bed rest and after 7-10 days of bed rest, while on placebo and after intravenous atropine. Spectra were derived by Fourier analysis of 128 interbeat interval data sets. Spectral power was estimated by computing the root-mean-square (rms) values (mean +/- SD) for the band encompassing the 2nd to 64th harmonics from subjects with a sufficient number of beats: placebo rms is 93 +/- 33 ms for pre-bed rest and 84 +/- 38 ms for bed rest (NS, n = 6); atropine rms is 63 +/- 24 ms for pre-bed rest and 40 +/- 23 ms for bed rest (P less than 0.01; n = 7). These data suggest that atropine "unmasks" a deconditioning effect of bed rest in athletic men, evidenced by a reduction in interbeat interval spectral power not apparent with placebo. Spectral analysis offers a useful means of quantitating the effects of bed-rest deconditioning and autonomic perturbations on cardiac dynamics.
Adult

Abstract: The severity of the symptoms of endometriosis has not always correlated well with the anatomic severity of the disease. This lack of correlation may be due to variations in the metabolic activity of the endometriotic implants present at different stages of the disease. Because prostaglandin F (PGF) has been implicated as a hormonal mediator of the clinical symptoms of endometriosis, PGF synthesis and content was measured in implants from 14 patients with mild, moderate, severe, or extensive disease. To assess whether PGF production was related to the status of implants, the authors classified implants, based on gross and histologic criteria, as petechial or reddish; intermediate or brown; or powder-burn or black. PGF production of implants from patients with mild or moderate disease was greater than that of implants from patients with severe or extensive disease (P less than 0.05), and PGF content was similar for all stages of endometriosis. Petechial implants produced twice the amount of PGF than intermediate implants (P less than 0.05), which in turn produced more PGF than powder-burn implants (P less than 0.05). Powder-burn implants did not have the in vitro capacity to produce PGF, and the amount of PGF contained in implants of all classes was similar. Therefore, endometriotic implant PGF production and possibly other biochemical activities are dependent on the physical status of the implant. The classification of implants by morphologic appearance may afford additional assistance in determining the prognosis of the disease and in the examination of the subtle effects of the disease on symptoms.
Adult