Nicolau G Y, Haus E, Lakatua D J, Bogdan C, Popescu M, Petrescu E, Sackett-Lundeen L, Stelea P, Stelea S
Endocrinologie. 1983 Oct-Dec;21(4):243-55.
Groups of 49-51 elderly men and women 77 +/- 8 years of age, institutionalized at the Berceni Clinical Hospital, Bucharest, Romania, were studied over a 24 hour span in spring, summer, fall and winter. All subjects followed a diurnal activity pattern with rest at night and ate three meals per day with breakfast at about 08:30, lunch at about 13:00, dinner at 18:30. The meals were similar, although not identical for all subjects during all seasons. On each day of sampling, blood was collected at four hourly intervals over a 24 hrs span. Immunoreactive insulin (IRI) and C-peptide were determined in plasma and glucose (during fall and winter only) in serum. Circadian variations of all three parameters were found and the rhythm parameters were determined statistically by cosinor analysis. The acrophases of the circadian rhythm of IRI and C-peptide were the same during all four seasons. The circadian acrophase of plasma IRI and C-peptide precedes that of serum glucose. The circadian mean concentrations of IRI and C-peptide show a circannual variation with higher values in winter and fall than in spring and summer for plasma insulin and with higher values for summer and fall than in spring for C-peptide. Sex differences in IRI and C-peptide concentrations with higher values in men are manifested during certain circadian and circannual stages but not during others.
在罗马尼亚布加勒斯特的贝尔塞尼临床医院，对年龄在77±8岁、每49至51人为一组的老年男性和女性进行了研究，研究时间跨度为春夏秋冬四季的24小时。所有受试者都遵循白天活动、夜间休息的昼夜活动模式，每天吃三餐，早餐约在8:30，午餐约在13:00，晚餐在18:30。虽然四季中所有受试者的餐食并非完全相同，但都相似。在每个采样日，在24小时内每隔4小时采集一次血液。测定血浆中的免疫反应性胰岛素（IRI）和C肽以及血清中的葡萄糖（仅在秋冬季节）。发现了所有这三个参数的昼夜变化，并通过余弦分析对节律参数进行了统计学测定。在所有四个季节中，IRI和C肽昼夜节律的峰值相位相同。血浆IRI和C肽的昼夜峰值相位先于血清葡萄糖的峰值相位。IRI和C肽的昼夜平均浓度呈现出年周期变化，血浆胰岛素在冬季和秋季的值高于春季和夏季，C肽在夏季和秋季的值高于春季。在某些昼夜和年周期阶段，男性的IRI和C肽浓度存在性别差异，男性的值较高，但在其他阶段则不存在。
