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.

[EX Q]: Abstract: To determine the timing of symptoms and oocyst excretion after the acquisition of cryptosporidium infection, we used a screening parasitologic stool examination to identify patients and then contacted them for the collection of retrospective histories and follow-up stool specimens. The study included 68 otherwise healthy patients with an identifiable source and time of infection. All 68 had diarrhea, 61 had abdominal pain, most also had other gastrointestinal symptoms, 33 had fever, and all recovered spontaneously. Among the 50 patients who submitted follow-up stool samples, more than 90 percent of the 610 symptomatic days and of the 136 oocyst-positive stools occurred between days 7 and 28 of infection, the mean incubation period was 7.2 days (range, 1 to 12), and the mean duration of illness was 12.2 days (range, 2 to 26). During the oocyst-excretion period cryptosporidium was detected in 90 percent of Ziehl-Neelsen-stained fecal concentrates. The end of oocyst excretion could be accurately determined in 26 patients; 19 (73 percent) had positive stools after the cessation of symptoms for a mean period of 6.9 days (range, 1 to 15). Fourteen patients were studied for two or more months, and in three of them asymptomatic episodes of oocyst excretion were detected up to two months after clinical recovery. We conclude that many cases of symptomatic cryptosporidiosis occur among immunocompetent patients, some of whom may excrete oocysts even when they have become asymptomatic. Conversely, infected symptomatic patients may occasionally have intermittently negative stools.
[EX A]: Abdomen

[EX Q]: Abstract: The pharmacokinetic characteristics of testosterone propionate were studied in normal men after a single im dose of 25 mg testosterone propionate-19,19,19-d3. Plasma levels of testosterone propionate-19,19,19-d3, its active metabolite testosterone-19,19,19-d3, and endogenous testosterone were measured by gas chromatography-mass spectrometry. Testosterone propionate-19,19,19-d3 was gradually transferred from the im injection site to the systemic circulation. The plasma levels of testosterone propionate-19,19,19-d3 were maintained at 2-4 ng/ml between 3 and 36 h after administration. Plasma testosterone-19,19,19-d3 levels were maintained above the physiological testosterone level for 48 h, while plasma levels of endogenous testosterone changed little.
[EX A]: Adult

[EX Q]: Abstract: When dog lung lobes were perfused at constant arterial inflow rate, occlusion of the venous outflow (VO) produced a rapid jump in venous pressure (Pv) followed by a slower rise in both arterial pressure (Pa) and Pv. During the slow rise Pa(t) and Pv(t) tended to converge and become concave upward as the volume of blood in the lungs increased. We compared the dynamic vascular volume vs. pressure curves obtained after VO with the static volume vs. pressure curves obtained by dye dilution. The slope of the static curve (the static compliance, Cst) was always larger than the slope of the dynamic curve (the dynamic compliance, Cdyn). In addition, the Cdyn decreased with increasing blood flow rate. When venous occlusion (VO) was followed after a short time interval by arterial occlusion (AO) such that the lobe was isovolumic, both Pa and Pv fell with time to a level that was below either pressure at the instant of AO. In an attempt to explain these observations a compartmental model was constructed in which the hemodynamic resistance and vascular compliance were volume dependent and the vessel walls were viscoelastic. These features of the model could account for the convergence and upward concavity of the Pa and Pv curves after VO and the pressure relaxation in the isovolumic state after AO, respectively. According to the model analysis, the difference between Cst and Cdyn and the flow dependence of Cdyn are due to wall viscosity and volume dependence of compliance, respectively. Model analysis also suggested ways of evaluating changes in the viscoelasticity of the lobar vascular bed. Hypoxic vasoconstriction that increased total vascular resistance also decreased Cst and Cdyn and appeared to increase the vessel wall viscosity.
[EX A]:
Animal