A clinical comparison of SIDS and explained sudden infant deaths: how healthy and how normal? CESDI SUDI Research Group. Confidential Inquiry into Stillbirths and Deaths in Infancy study.

OBJECTIVES: To compare the clinical characteristics associated with sudden infant death syndrome (SIDS) and explained sudden unexpected deaths in infancy (SUDI). DESIGN: Three year population based, case control study with parental interviews for each death and four age matched controls. SETTING: Five regions in England (population, > 17 million; live births, > 470,000). SUBJECTS: SIDS: 325 infants; explained SUDI: 72 infants; controls: 1,588 infants. RESULTS: In the univariate analysis, all the clinical features and health markers at birth, after discharge from hospital, during life, and shortly before death, significant among the infants with SIDS were in the same direction among the infants who died of explained SUDI. In the multivariate analysis, at least one apparent life threatening event had been experienced by more of the infants who died than in controls (SIDS: 12% v 3% controls; odds ratio (OR) = 2.55; 95% confidence interval (CI), 1.02 to 6.41; explained SUDI: 15% v 4% controls; OR = 16.81; 95% CI, 2.52 to 112.30). Using a retrospective illness scoring system based on "Baby Check", both index groups showed significant markers of illness in the last 24 hours (SIDS: 22% v 8% controls; OR = 4.17; 95% CI, 1.88 to 9.24; explained SUDI: 49% v 8% controls; OR = 31.20; 95% CI, 6.93 to 140.5). CONCLUSIONS: The clinical characteristics of SIDS and explained SUDI are similar. Baby Check might help identify seriously ill babies at risk of sudden death, particularly in high risk infants.

Juvenile hormone and juvenile hormone mimics inhibit proliferation in a lepidopteran imaginal disc cell line.

The action of juvenile hormone (JH) and JH mimics have been examined in vitro by utilizing the imaginal disc-derived cell line, IAL-PID2. We have discovered that the cell line was responsive to JH and a variety of JH mimics. The most consistent response obtained in our studies was inhibition of cell proliferation, in the absence of 20-hydroxyecdysone (20E), which characteristically reduces cell proliferation in its own right in this cell line. JH-I, JH-III, methoprene, fenoxycarb, and farnesol significantly inhibited cell proliferation after 3 days of exposure of the cells in vitro to each of the compounds. Linoleic acid controls had no effect on proliferation in the cultures. The cell proliferation assay demonstrates the JH responsiveness of this cell line, but the concentrations of JH required were high compared to the concentrations of 20E needed for inhibition of proliferation in these cells.

Epidemiology of SIDS and explained sudden infant deaths. CESDI SUDI Research Group.

OBJECTIVES: To establish whether epidemiologic characteristics for sudden infant death syndrome (SIDS) have changed since the decrease in death rate after the "Back to Sleep" campaign in 1991, and to compare these characteristics with sudden and unexpected deaths in infancy (SUDI) from explained causes. DESIGN: Three-year, population-based, case-control study. Parental interviews were conducted soon after the death and for 4 controls matched for age and date of interview. All sudden unexpected deaths were included in the study and the cause of death was established by a multidisciplinary panel of the relevant health care professionals taking into account past medical and social history of the mother and infant, the circumstances of death, and a full pediatric postmortem examination. Contributory factors and the final classification of death were made using the Avon clinicopathologic system. SETTING: Five regions in England, with a total population of >17 million people, took part in the study. The number of live births within these regions during the particular time each region was involved in the study was 473 000. STUDY PARTICIPANTS: Three hundred twenty-five SIDS infants (91.3% of those available), 72 explained SUDI infants (86.7% of those available), and 1588 matched control infants (100% of total for cases included). RESULTS: Many of the epidemiologic features that characterize SIDS infants and families have remained the same, despite the recent decrease in SIDS incidence in the United Kingdom. These include the same characteristic age distribution, few deaths in the first few weeks of life or after 6 months, with a peak between 4 and 16 weeks, a higher incidence in males, lower birth weight, shorter gestation, and more neonatal problems at delivery. As in previous studies there was a strong correlation with young maternal age and higher parity and the risk increased for infants of single mothers and for multiple births. A small but significant proportion of index mothers had also experienced a previous stillbirth or infant death. The majority of the SIDS deaths (83%) occurred during the night sleep and there was no particular day of the week on which a significantly higher proportion of deaths occurred. Major epidemiologic features to change since the decrease in SIDS rate include a reduction in the previous high winter peaks of death and a shift of SIDS families to the more deprived social grouping. Just more than one quarter of the SIDS deaths (27%) occurred in the 3 winter months (December through February) in the 3 years of this study. In half of the SIDS families (49%), the lone parent or both parents were unemployed compared with less than a fifth of control families (18%). This difference was not explained by an excess of single mothers in the index group. Many of the significant factors relating to the SIDS infants and families that distinguish them from the normal population did not distinguish between SIDS and explained SUDI. In the univariate analysis many of the epidemiologic characteristics significant among the SIDS group were also identified and in the same direction among the infants dying as SUDI attributable to known causes. The explained deaths were similarly characterized by the same infant, maternal, and social factors, 48% of these families received no waged income. Using logistic regression to make a direct comparison between the two index groups there were only three significant differences between the two groups of deaths: 1) a different age distribution, the age distribution of the explained deaths peaked in the first 2 months and was more uniform thereafter; 2) more congenital anomalies were noted at birth (odds ratio [OR] = 3.14; 95% confidence intervals [CI]: 1.52-6. (ABSTRACT TRUNCATED)

Effects of cycloheximide on cellular elongation in aManduca sexta cell line.

A clone (GV1) of the CHIManduca sexta cell line responds to 20-hydroxy-ecdysone by changing cellular shape from an epithelial-like form to an elongated fibroblast-like form. We have determined that this morphological response to hormone is prevented by treatment with cycloheximide. The inhibition of the elongation response by cycloheximide may relate to a requirement for the synthesis of specific proteins that play a role in the formation of cytoskeletal structure.

Protein synthesis in imaginal disks of Plodia interpunctella during development in vivo and in vitro.

Wing imaginal disks were dissected from larvae of Plodia interpunctella (Hübner) at various stages during the larval-pupal transformation. The wing-disk proteins separated by electrophoresis and scanned with a densitometer changed quantitatively but not qualitatively during development in vivo. Treatment of wing disks in vitro with beta-ecdysone resulted in a 2-fold increase in synthesis of proteins after only 2 hr incubation. The maximum rate of protein synthesis was reached 16 hr after treatment with hormone. The pattern of proteins separated by electrophoresis of wing disks that were incubated in vitro with beta-ecdysone did not change qualitatively. The major features of protein synthesis during wing-disk development in vivo were similar to those observed during beta-ecdysone-induced development in vitro.

Chitin biosynthesis in imaginal discs cultured in vitro.

We have investigated the stimulation of cuticle production by imaginal discs ofPlodia interpunctella in tissue culture. We turned to biochemical methods to assess the quantitative effects of beta-ecdysone on chitin biosynthesis in wing discs incubated with 0.5 µC of C14-glucosamine for the final 24 h of culture.We demonstrated that imaginal discs ofP. interpunctella respond to increasing concentrations of ß-ecdysone with increased synthesis. The threshold is between 0.01 and 0.1 µg/ml of hormone (2×10-8 M to 2×10-7 M). These data represent the first demonstration of quantitative biosynthesis of chitin by a developing tissue in vitro in relation to varying amounts of hormone. Additionally, protein synthesis during the ß-ecdysone-dependent period was necessary for chitin synthesis. This system thus lends itself to a detailed investigation of the control of chitin biosynthesis.

Ultrastructure of cuticle deposited inPlodia interpunctella wing discs after variousß-ecdysone treatments in vitro.

Wing discs of the Indian meal moth may be cultured for extended periods in vitro. The discs produced a tanned cuticle after continuous incubation with ß-ecdysone in medium conditioned with fat body or after a 24-h pulse incubation with ß-ecdysone in plain medium. We investigated the ultrastructure of the cuticle deposited by such discs. We found that the treatment that produced the most complete cuticle in vitro was the 24-h pulse of hormone. We observed that cuticle formation in vitro was not "all-or-none." Depending on culture conditions, discs produced cuticulin only, complete epicuticle, epicuticle plus diffuse endocuticle, epicuticle plus lamellate endocuticle, or even multiple layers of cuticle. The ultrastructural evidence suggests that continuous incubation with ß-ecdysone in plain medium does not always inhibit cuticle formationper se, but does prevent tanning of the partially formed cuticle.