Sudden Infant Death Syndrome Group Research Articles

Immunocytologic characterization using monoclonal antibodies of lung lavage cell phenotype in infants who have died from sudden infant death syndrome.

The phenotype of cells obtained from pulmonary lavage in infants who have died from sudden infant death syndrome were examined and compared with cells from control subjects. The only striking difference between the groups was a lack of reactivity of lavage cells with antibody of the CD14A cluster in the sudden infant death syndrome subjects, while antibodies of the CD14B cluster reacted strongly with cells from both the sudden infant death syndrome group and controls. Major histocompatibility complex class II antigens were expressed on approximately 95% of lavage cells, with DQ expressed more frequently than DR or DP. The majority of the lavage cells was macrophages, yet they reacted with CD3 (OKT3) and CD8 (OKT8) antibodies. No interleukin 2 was found in the lavage fluid.

Lead in human bones. Investigations on an occupationally non-exposed population in Southern Bavaria (F.R.G) II. Children

The concentration of lead in three different bones (pelvic bone, cortical part of the mid-femur, petrous portion of the temporal bone) of 82 children who died in 1984 was determined by graphite furnace atomic absorption spectrometry. Three age classes were selected: < 1 year ( n = 25); 1–6 years ( n = 18); 10–20 years ( n = 35). The Pb content of all three types of bone increased steadily with age, and was most pronounced in the temporal bone. The differentiation of the bones with respect to the Pb concentration, as seen in adults, increased from babies (geom. mean, temporal bone 0.33 mg/kg wet wt., femur 0.33, pelvic bone 0.26) to pre-school children (0.62; 0.74; 0.49) and to youths (1.76: 1.18; 0.63). Babies showed no dependence of the Pb concentration in bone on sex. For pre-school children, in all three bones the concentration of Pb in girls was higher, while for youths, the concentration in males exceeded that found in females. In any sub-group the bones from urban children showed on average higher Pb concentrations than those from rural areas. For the mid-femur, and the age class 10–20 years, this difference was statistically significant. No difference was seen in the mean Pb concentration in bones of SIDS (sudden infant death syndrome) and non-SIDS babies, but in the temporal bone the distribution of the Pb concentrations for the SIDS group was significantly greater than that of the control babies. The mean lead body burden was calculated to be 0.32 mg Pb for babies, 1.25 mg Pb for pre-school children and 7.12 mg Pb for youths. Compared with a study in 1974 in the same area, the reduction of the lead burden of children was even greater (femur 3.5 times: pelvic bone 2.6 times) than for adults (mean: femur 1.3 times; pelvic bone 1.7 times).

Sudden Infant Death Syndrome and Post Perinatal Mortality in Norwegian Birth Cohorts 1967‐1980

The well established effects of maternal age and birth order in sudden infant death syndrome (SIDS) formed the basis for a comparison with other categories of post perinatal death in an attempt to shed some light on the etiologic roles played by ante and postnatal factors. A total of 826,162 children, born 1967 through 1980 and recorded at the Medical Birth Registry of Norway was at risk to die during the post perinatal period (ages 7 through 364 days). Out of the 3,582 infants who died, 1,062 were considered SIDS. Strong effects of maternal age (negative) and birth order (positive) were found in the SIDS group, but not to the same extent in the non-SIDS group or the group of congenital malformations. Likewise, the excess risk in children of unmarried mothers was higher in the SIDS group. The suggested effects of postnatal factors in the causation of SIDS may seem promising from a preventive point of view. The strength of the effects of maternal age and birth order necessitate adjustment for these variables in future epidemiological studies of SIDS.

Respiratory and heart rate patterns in infants destined to be victims of sudden infant death syndrome: average rates and their variability measured over 24 hours.

From a prospective study in which 24 hour recordings of the electrocardiogram and respiratory activity (abdominal wall movement) were made on a population of full term infants, 22 recordings were obtained from 16 infants who later were victims of the sudden infant death syndrome. The average heart rate, average heart rate variability, average breath to breath interval, and average breath to breath interval variability over the whole of each recording for the 22 recordings were compared with those from a control group of 324 infants selected at random from the rest of the population. No significance was found in the number of recordings from those infants who suffered the sudden infant death syndrome which lay outside the 5th-95th percentile range of the control group for the four variables studied. In a group comparison no difference was found between the sudden infant death syndrome group and the controls either in terms of the respiratory variables studied or in terms of the average heart rate variability. The results did, however, suggest that there may be a group difference in terms of the average instantaneous heart rate.

Sudden infant death syndrome: abnormalities in short term fluctuations in heart rate and respiratory activity.

In order to test the hypothesis that a defect in cardiorespiratory regulation contributes to death of infants from sudden infant death syndrome (SIDS), we analyzed the power spectra of heart rate and respiratory activity during 256-sec epochs of quiet sleep. Data were obtained from pneumogram recordings performed for 12 h at night on eight infants who subsequently died from SIDS and 22 age-matched control infants. We computed the heart rate and respiratory power spectra from a single epoch on each infant using an algorithm developed for an 8085 microprocessor system dedicated to this investigation. There was no statistically significant difference between SIDS and controls based on mean respiratory and heart rates. Spectral analysis revealed enhancement of low frequency power in the 0.02 to 0.1 Hz band in the heart rate power spectrum in the SIDS group compared to control (p less than 0.002) and dispersion in respiratory frequency as determined by the respiratory band width (p less than 0.00001). These data suggest that a predisposition to SIDS manifests itself in an abnormal pattern of fluctuations in heart rate and respiratory activity.

‘Reactive Gliosis’ in the Medulla Oblongata of Victims of the Sudden Infant Death Syndrome

A current hypothesis that the sudden infant death syndrome (SIDS) is a sleep apnea syndrome precipitated by defective control of involuntary respiration prompted the present study in which "reactive gliosis" in sections of the medulla oblongata of 45 SIDS victims was quantitated and compared with that in 20 control infants. Six anatomic regions were studied; five are related and one is unrelated to neural control of involuntary respiration. Increased numbers of "reactive" astrocytes were found in the SIDS group when the counts for all regions were combined (P = .04). Counts were also significantly higher in the SIDS victims for each of three regions alone: (1) the hilum of the inferior olivary nucleus (P = .01); (2) a lateral region (P = .02); and (3) the nucleus of the tractus solitarius (P = .03). The region with the greatest statistical difference, the inferior olivary hilum, has no recognized role in the control of involuntary respiration. There were no consistent associations between reactive astrocyte counts and specific clinical, socioeconomic, and pathologic variables. Characterization of the SIDS group whose counts exceeded that of the highest control infant also did not uncover distinguishing features. This study reinforces previous observations that, at least statistically, an abnormality of the brainstem occurs in a group of SIDS victims in contrast to a group of control infants, but also discloses considerable overlap in the numbers of such cells between these two groups.

Thyroid hormones in the sudden infant death syndrome (SIDS)

Results are presented of serum total T4, T3, and TSH measurements on 92 patients. There are 34 infants exhibiting the sudden infant death syndrome, 36 in control group 1, who are matched both for age of infant and for duration of storage of specimen, and 22 post-mortem sera from non-SIDS deaths. There is no significant difference between the groups for total T4 measurements, but there is a highly significant elevation of both total serum T3 and TSH in the SIDS group compared with control group 1. It is suggested that the TSH elevation may be due to a post-mortem effect, but the T3 results appear to confirm and extend the recent publication of Chacon et al [1]. Evidence of one case of a near-SID that subsequently died is presented, demonstrating that disturbances of thyroid function tests occurred in this patient before death.

A study of the endogenous opioid system in the sudden infant death syndrome

To investigate the possible role of the endogenous opioid system in the pathogenesis of the sudden infant death syndrome (SIDS), we measured met-enkephalin immunoreactivity by radioimmunoassay in brain, lung, and adrenal glands of SIDS victims and of infants (controls) dying of nonneurologic causes. Met-enkephalin was stable in brain tissue up to 24 hours after death. On inspection, met-enkephalin levels in the cerebral cortex of SIDS victims were similar to those in controls. Levels in the caudate nucleus were lower in infants than in adults. In the medulla, the levels in SIDS cases and controls were not found to differ significantly. The linear relationship between the levels in the medulla and age was not detectably different in SIDS and controls. However, as a subset, levels in the control group significantly decreased with increasing age ( P = 0.005), whereas levels in the SIDS group showed no correlation with age ( P = 0.33). Levels of met-enkephalin in the adrenal gland of SIDS victims were similar to those in controls and were considerably lower than adult values. Lung tissue was assayed for beta-endorphin immunoreactivity and met-enkephalin: for both peptides the values in SIDS cases were low (femtomolar range) and similar to those in controls. These data suggest that met-enkephalin is not markedly overproduced in brains of SIDS victims. Future postmortem studies should focus on more subtle evidence of endogenous opioid overactivity such as differences in age related changes, receptor number, and levels of other endogenous opioid peptides.

Diaphragm Strength in Near-Miss Sudden Infant Death Syndrome

Diaphragm muscle strength was measured as maximal transdiaphragmatic pressure during airway occlusion in ten near-miss sudden infant death syndrome infants aged 4.1 +/- 0.6 (SE) months post-term, range 2 to 7 months, and ten control infants aged 4.5 +/- 0.8 months post-term, range 0.8 to 8 months. In the near-miss sudden infant death syndrome group, the mean maximal transdiaphragmatic pressure was 106 +/- 6 cm H2O, range 78 to 132 cm H2O, compared with a mean maximal transdiaphragmatic pressure 86 +/- 4 cm H2O, range 69 to 106 cm H2O, in the control group. Diaphragm strength is normal or increased in near-miss sudden infant death syndrome infants.

Perinatal indicators of sudden infant death syndrome: A study of 34 Rhode Island Cases

Pre- and perinatal characteristics of 34 victims of Sudden Infant Death Syndrome (SIDS) were compared with those controls matched for sex, race, birthdate, and hospital. Data were collected retrospectively from hospital records. Factors which reliably differentiated the SIDS group from controls included low birth-weight, short second stage of labor, fewer years of maternal schooling, and maternal anemia during pregnancy. The constellation of findings was interpreted as reflecting the interaction of physiological predispositions and environmental “setting conditions”, culminating in sudden and unexpected death. The efficacy of a previously established SIDS risk scale was assessed for these cases. Some issues concerning prediction of outcome from perinatal variables are discussed.

Sudden infant death in Copenhagen 1956--1971. III. Perinatal and perimortal factors.

139 cases of the Sudden Infant Death Syndrome (SIDS) among infants born in the Municipality of Copenhagen during the period 1956--1971 were analysed on the basis of data collected from police reports and (for 131 cases) from the infant health visitors' records. In the SIDS group there was a greater male preponderance than among others dying in the same age range. Compared with the living controls, the SIDS mothers had attended less prenatal examinations, more often delivered their babies at home; the SIDS parents were younger, and yet the SIDS infants were less often firstborns. There was no difference with respect to history of abortions, maternal state of health during pregnancy, or events at delivery. The age at death for the SIDS infants is of a distribution similar to that for fatal respiratory infections. Prematures died later than matures, but this difference is not statistically significant. It is concluded that perinatal factors and SIDS are correlated, but owing to changes in predisposing factors and decreasing differences between cases and controls in recent years as well as interdependence of the factors, it seems doubtful whether the incidence of SIDS can be reduced by alleviating the above-mentioned unfavourable factors.

Intrapartum fetal heart rate and sudden infant death syndrome

The intrapartum fetal heart rate (FHR) tracings of 20 infants who died of sudden infant death syndrome (SIDS) and 20 matched control infants, both drawn from a population at increased obstetrical risk, were compared. This is a blind retrospective study aimed at quantifying (a) the incidence of FHR patterns, (b) the range of FHR and variability levels, and (c) the episodes of variable and late decelerations occurring in conjunction with abnormal FHR levels. Tracings of SIDS infants were similar to those of control infants. Although the three infants with bradycardic FHR levels were restricted to the SIDS group, infants in this group could not be reliably differentiated from control infants on the basis of intrapartum FHR tracings.