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

[EX 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.
[EX A]: Breast cancer risk in relation to early oral contraceptive use.

[EX Q]: Abstract: Glycine and gamma-aminobutyric acid (GABA) are inhibitory transmitters of major importance. Whereas neurones using GABA as the transmitter can be visualized by immunocytochemical methods for glutamate decarboxylase (GAD) or GABA, no comparable techniques have been available for the selective visualization of glycinergic neurones. We have now produced polyclonal antibodies which specifically recognize glycine in glutaraldehyde-fixed tissue. We used these antibodies to investigate the distribution of glycine in the simple central nervous system (CNS) of the Xenopus embryo, which contains an anatomically and physiologically defined class of reciprocal inhibitory interneurones, the commissural interneurones. These interneurones have an important role in the generation of the swimming motor pattern and are thought to be glycinergic. The glycine antibodies specifically stain these interneurones, revealing their distribution and number in the embryo CNS. This is the first demonstration of the selective localization of glycine-like immunoreactivity in a putative glycinergic class of neurone that has been characterized physiologically, pharmacologically and anatomically.
[EX A]: Inhibitory neurones of a motor pattern generator in Xenopus revealed by antibodies to glycine.

[EX Q]: Abstract: The long-term health consequences of chronic physical activity for patients with type I diabetes are unknown. In the current study, the association of physical activity to diabetic complications was assessed in 696 type I diabetic individuals diagnosed between 1950 and 1964. Participation in team sports in high school or college was not associated with a decreased prevalence of severe retinopathy or blindness later in life. There was, however, a suggestion of a negative association between physical activity and both cardiovascular disease and overall mortality, ie, individuals who participated in team sports were somewhat less likely to report macrovascular disease at follow-up or to have died than nonparticipants. The relationship between physical activity and diabetic complications only appeared in male subjects. The results suggest that activity early in life by patients with type I diabetes does not appear to be associated with an adverse health effect and may, in fact, be beneficial.
[EX A]:
Pittsburgh Insulin-Dependent Diabetes Mellitus Morbidity and Mortality Study: physical activity and diabetic complications.