Role of school schedule, age, and parental socioeconomic status on sleep duration and sleepiness of Parisian children.

The aim of the study was to assess the duration and quality of sleep of prepubertal (Tanner Scale level 1) physically and mentally healthy children as a function of school schedule (4 versus 4.5 days per week), age and grade (median age of 9.5 years for 4th grade versus median age of 10.5 years for 5th grade), school district (wealthy versus nonwealthy) in Paris, France, and parental socioeconomic status (high, medium, or low). We studied 51 girl and 44 boy volunteer pupils with written parental consent. The study lasted 2 weeks during the month of March. During the first study week, the children attended school 4.5 days, and during the second week, they attended school only 4 days without difference in the length of the school day. A sleep log was used to ascertain time of lights off for sleep and lights on at awakening, nighttime sleep duration, and self-rated sleep quality. A visual analog scale (VAS) was also used by pupils to self-rate the level of perceived sleepiness at four specific times of the school day. Conventional statistical methods (e.g., t and chi2 tests) were used to examine differences in mean values. Sleep duration, self-rated sleepiness, and subjective sleep quality were comparable (P > .05) by gender, school schedule, school district, and parental socioeconomic status. Overall, the sleep of this sample of Parisian children around 10 years of age was rather stable in its duration and timing, suggesting flexibility to adjust to the different school schedules.

A histological assessment of the four-day subrenal capsule assay (SRCA).

A four-day subrenal capsule assay (SRCA) was developed, since fragments of human tumours implanted under the renal capsule of immunocompetent mice became rejected by the host within six days. The assay requires a histological assessment of both its exploitability and the extent of drug-induced anti-tumour lesions. 45 tumours from 43 patients with solid tumour were submitted to an SRCA in 1410 male B6D2F1 mice. After being biopsied each tumour was dissected by a pathologist, cut into 50 pieces (1.5 mm3), and one piece was implanted under the renal capsule of 35 mice; the mean tumour diameter was measured on day 0. The mice were randomized into groups of 6 to 10 animals each. On days 1, 2 and 3, the mice were treated with either placebo (control group) or with various anticancer agents. On day 4 the animals were sacrificed, the mean tumour diameter measured, the tumour bearing kidney fixed in Bouin's picroformol solution and processed for histological analysis after staining with hematein. Fragments of fresh explants of human tumours retained their proliferative and metabolic capacity: mitoses were observed as well as keratinizing cells in epidermoid carcinomas and melanin-producing cells in melanomas. Proliferation of tumour cells was seen along the renal capsule suggesting their affinity for connective tissue. Capillaries filled with mouse erythrocytes were also seen. No or minimal lymphocytic infiltration was found. Drug oncolytic effects ranged from minor cellular degeneration to almost complete necrosis and were documented by the scoring of histologic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)