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.

Q: Abstract: CT of compression fractures is a useful adjunct to the plain x-ray in excluding signs of metastasis. However, increased bone density on CT may not distinguish osteoporotic fractures from neoplastic disease, in which case radioiodine scan, bone and marrow biopsies, or myelography may be necessary. Surgery for painful osteoarthritic spinal disease is controversial. The potential advantages of surgery must be weighted against the risk of anesthesia, the length and tolerance of postoperative immobility, and the effect of laminectomy and fusion on the biomechanics of the spine. Furthermore, the elderly are at increased risk for postoperative complications.

A: Aged
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Q: Abstract: After fertilization, the protein products of the Drosophila homeobox gene caudal (cad) accumulate in a concentration gradient spanning the anteroposterior axis of the developing embryo. Mutations in the cad gene that reduce or eliminate the gradient cause abnormal zygotic expression of at least one segmentation gene (fushi tarazu) and alter the global body pattern.

A: Animal
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Q: Abstract: We studied eight women who had complex partial seizures and anovulatory cycles or inadequate luteal phases. Progesterone suppositories were given during the premenstrual phase or entire second half of the cycle in doses of 50 to 400 mg q12h. Antiseizure medication levels were kept in the therapeutic range. Average monthly seizure frequency declined by 68% (p less than 0.05, Wilcoxon matched-pairs test) in a 3-month treatment period compared with the 3 months prior to therapy, and six of the eight women had fewer seizures. None experienced more seizures or disruption of menses. Transient tiredness and depression were noted in some when progesterone dosage was raised above minimally effective levels. These symptoms cleared within 48 hours of lowering the dosage. The value of intermittent natural progesterone therapy as a safe, well-tolerated, and effective adjunct to antiseizure therapy should be assessed further.

A:
Administration, Intravaginal
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