Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Q: Abstract: Inflammatory bowel diseases (IBD) has been characterized as having an autoimmune background. We studied the presence of immune interferon in the sera of a small number of patients with IBD. Antiviral activity was detectable in the sera of our patients with well-controlled IBD but it was mainly weak-positive (50% inhibition of virus CPE in a dilution of 1:10 per 0.2 ml of serum). The antiviral activity varied according to the sensitivity of the cell line used. The human amnion cells Wish (81%) and the human embryonic Intestine-407 (73%) were more sensitive.

A: Circulating interferon-like activity in inflammatory bowel disease.
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Q: Abstract: It has been suggested that the risk of breast cancer is increased by oral contraceptive use before the first birth, or by use before age 25, particularly if certain formulations are used. These hypotheses were evaluated in a hospital-based case-control study. A total of 521 patients under age 45 with breast cancer were compared with 521 controls matched for age, time of interview, and geographic area. Oral contraceptive use before the first birth was reported by 155 patients and 137 controls. With allowance for confounding by multivariate analysis, the estimated relative risk was 1.0 (95% confidence interval, 0.6-1.5). The estimate was 1.0 (0.2-3.9) for any use among nulliparous women and 0.6 (0.3-1.3) for use before the first birth among parous women. Use before age 25 was reported by 145 patients and 141 controls, and the multivariate relative risk estimate was 1.0 (0.7-1.6); the results were similar when use of specific formulations was examined. For oral contraceptive use before either the first birth or age 25, the relative risk estimates were compatible with 1.0 for use of five or more years' duration or an interval since first use of at least 15 years. There was also no evidence of an increased risk in any subgroup including those at increased underlying risk because of factors such as a family history of breast cancer or a history of cystic breast disease. The findings suggest that, up to age 45, the risk of breast cancer is not influenced by the use of oral contraceptives before the first birth or before age 25 even if the use lasted for five or more years.

A: Breast cancer risk in relation to early oral contraceptive use.
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Q: Abstract: Deformities are abnormalities of shape or form caused by abnormal or imbalanced mechanical forces. In prenatal deformation, most infants are intrinsically normal and the deformation results from extrinsic constraining forces. Most prenatal deformities will resolve spontaneously or with the application of counteracting forces. In contrast, postnatal deformities result from either extrinsic pathologic processes, affecting the bones, nervous system, or muscle and resulting in the application of abnormal forces to bone, or normal forces acting on intrinsic diseases of bone. While many postnatal deformities can be contained or corrected by the application of counteracting forces, aggressive physical therapy, casting, or surgery is often required for correction.

A:
The origin of prenatal and postnatal deformities.
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