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: Neutrophils have been shown to express a receptor for C3dg that is distinct from CR2 and is termed complement receptor type 4 (CR4). In the present study, other peripheral blood cell types were examined by indirect immunofluorescence and flow cytometry for the presence of C3dg binding activity. Specific uptake of C3dg occurred with neutrophils, platelets, and B lymphocytes, but not with eosinophils or T lymphocytes. Monocytes, contained within a mixed cell population of peripheral blood mononuclear cells and platelets, also bound C3dg, whereas purified monocytes did not. Binding of 125I-labeled glutaraldehyde-cross-linked C3dg to platelets was saturable, with an average of 1940 C3dg molecules bound per platelet at saturation (n = 8), ranging in number from 660 to 3930 molecules bound. Activation of platelets with thrombin did not consistently cause an increase in the expression of CR4 sites. 125I-C3dg binding to platelets was competitively inhibited equally well by unlabeled C3dg and iC3b, and approximately fourfold less well by C3b. The addition of platelets to elutriated monocytes generated C3dg binding activity on these cells by the formation of platelet-monocyte complexes. Thus, the CR4 on platelets accounted for the C3dg binding activity initially observed with partially purified monocytes. The adherent property of platelets may enable them to confer on certain other cell types the ability to localize C3dg-coated immune complexes or particles.

Output: Blood Platelets

Input: Consider Input: Abstract: Upper airway obstruction is usually diagnosed by visual examination of maximum expiratory and inspiratory flow-volume curves and by calculating a ratio of expiratory to inspiratory flow at 50 percent of vital capacity (mid-vital capacity flow ratio); however, reference values of this ratio have not been well established, and considerable variability exists. The purpose of this study was to examine the range of mid-vital capacity flow ratios in a group of healthy subjects and to determine if some of the variability is accounted for by different maximum inspiratory pressures. We measured maximum expiratory and inspiratory flows at 50 percent of vital capacity from the flow-volume curves, and maximum inspiratory pressures in a group of 60 healthy nonsmokers (30 men and 30 women) whose ages ranged from 21 to 40 years. We found that mid-vital capacity flow ratio (mean +/- SD) was 0.72 +/- 0.19 in men and 0.77 +/- 0.18 in women. The coefficient of variation of the mid-vital capacity flow ratio was 28 percent for men and 23 percent for women. The 95 percent confidence limits for the mid-vital capacity flow ratio were 0.65 to 0.79 for men and 0.70 to 0.84 for women. Maximum inspiratory pressures (mean +/- SD) were 129 +/- 30 cm H2O in men and 91 +/- 16 cm H2O in women, not significantly different from previous studies. Normalizing maximum inspiratory flow for maximum inspiratory pressure did not reduce the coefficient of variation, which became 29 percent in men and 30 percent in women. We conclude that the range of mid-vital capacity flow ratios is wide, and it cannot be reduced by standardizing it for maximum inspiratory pressures.

Output: Adult

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