Postnatal changes in N-methyl-D-aspartate receptor binding and stimulation by glutamate and glycine of [3H]-MK-801 binding in human temporal cortex.

1. Homogenates of human infant and adult temporal cortex were used to measure [3H]-TCP and [3H]-MK-801 binding to the N-methyl-D-aspartate (NMDA)-coupled ion channel phencyclidine site. 2. Both [3H]-TCP and [3H]-MK-801 binding increased in infant cortex by > 100% between term and 26 weeks suggesting that the numbers of NMDA receptors increase during postnatal brain development. 3. [3H]-MK-801 binding was measured under non-equilibrium conditions in temporal cortex homogenates with the addition of 100 microM of L-glutamate plus a range of concentrations (0.05 microM-100 microM) of glycine. Glutamate and glycine increased [3H]-MK-801 binding by stimulating NMDA receptors and improving [3H]-MK-801 access to ion channel binding sites; maximum stimulation in adult and infant temporal cortex was achieved with 100 microM glutamate plus 5 microM glycine; a higher concentration of glycine (50 microM) reduced [3H]-MK-801 binding to below maximum. 4. The stimulation by 100 microM glutamate plus 5 microM glycine of [3H]-MK-801 binding in infant temporal cortex was affected by postnatal age. For example, although the stimulation of [3H]-MK-801 binding in 5-6 week infant cortex (236% of basal) was similar to adult cortex (230% of basal), in samples taken from infants aged 5-6 months glycine (plus glutamate) stimulation of [3H]-MK-801 binding (392% of basal) was substantially greater than that measured in adult temporal cortex. 5. The binding of [3H]-glycine to the glycine modulatory site associated with the NMDA receptor in infant cortex also increased with postnatal age by > 100% between term and 26 weeks. 6. It is concluded that NMDA receptors in infant cortex increase to levels greater than those in adult cortex during postnatal development. The results do not exclude the possibility that the transiently increased NMDA receptor-ion channel complex in infant cortex shows enhanced responses to agonists and modulators.

Hydrocolpos with peritonitis in the newborn.

Two cases of hydrocolpos are described presenting soon after birth. One infant who died on the first day had an intrauterine peritonitis caused by compression of the caecum on the pelvic brim. The other surviving infant developed a caecal perforation secondary to Hirschsprung's disease. Neither infant had rectal atresia, which is the commonest cause of intestinal obstruction in these infants. The association of hydrocolpos with polydactyly in one of these cases may represent an autosomal recessive trait.

Endocardial fibroelastosis in infants with hydrops fetalis.

Endocardial fibroelastosis, defined as an endocardium in excess of 30 microns thick, was found in 10 out of 34 cases of hydrops fetalis in a review of 1589 perinatal necropsies carried out between 1976 and 1989. The infants comprised 16 cases of rhesus haemolytic disease, of whom three had endocardial fibroelastosis, and 18 cases of non-rhesus hydrops, of whom seven had endocardial fibroelastosis. Intrauterine congestive heart failure was thought to have been the probable cause of hydrops in eight of the 10 infants with endocardial fibroelastosis. None of an age matched control group without endocardial fibroelastosis had evidence of congestive cardiac failure. These observations support the hypothesis that endocardial fibroelastosis is an endocardial response to chronic prenatal myocardial stress.

Pulmonary blastoma.

A case of pulmonary blastoma is described in a man dying at the age of 50 from hepatic and cerebral metastases. Eleven previously reported cases are reviewed and the histogenesis is discussed. It is concluded that these rare tumours are a distinct form of pulmonary carcinosarcoma in which the epithelial element is an adenocarcinoma. It is this that gives it its characteristic and probably coincidental histological resemblance to foetal lung and the evidence for a blastomatous origin is regarded as insufficient.

Pulmonary vascular candidiasis and use of central venous catheters in neonates.

A retrospective study of infant deaths in this maternity hospital carried out from 1976-86 showed a recent increase in fatalities with systemic candidiasis. Ten of twenty five cases occurred between July 1985 and June 1986. Most of these infants had Candida plugging pulmonary vessels, often accompanied by vasculitis, thrombosis, and parenteral lipid embolism. The adoption of central venous catheters for prolonged parenteral feeding of very preterm infants may have accounted for this phenomenon. Over the same decade there was an increased incidence of Candida isolates from all admissions to the neonatal intensive care unit: the prolonged survival of very low birthweight infants and the use of multiple courses of antibiotics were also factors.

Lethal challenge of gnotobiotic weanling rats with bacterial isolates from cases of sudden infant death syndrome (SIDS).

An attempt was made to produce an animal model of sudden infant death syndrome (SIDS). The experimental animals (germ free weanling rats) were exposed to nasopharyngeal isolates from cases of SIDS to test the hypothesis that common bacteria may have an aetiological role in the disease. Negative results were obtained when the strains were tested in isolation, but certain combinations of organisms (specifically some Staphylococcus aureus and Escherichia coli) killed the animals rapidly (less than 18 hours) without prolonged terminal illness. Post mortem histological findings were consistent with those of SIDS. The lethal toxigenic potential of nasopharyngeal bacteria, which are regarded as harmless in adults, should be reconsidered in respect of the aetiology of SIDS.

Immunohistological localisation of staphylococcal toxic shock syndrome toxin (TSST-1) antigen in sudden infant death syndrome.

A polyclonal antiserum to toxic shock syndrome toxin (TSST-1) and a standard immunoperoxidase technique were used on formalin fixed tissues from 50 cases of sudden infant death syndrome (SIDS) to determine if the syndrome was associated with bacterial infection. There was strong specific staining in the renal tubular cells in nine (18%) cases. A similar pattern of staining was seen in three of a series of 50 kidneys selected for comparison from a wide range of necropsy cases. The staining was finely granular within the cytoplasm of proximal convoluted tubular cells and diffuse in tubular cell nuclei. In an attempt to validate the staining pattern the immunoperoxidase technique was also performed on formalin fixed kidneys from rats which had been given intravenous injections of crude bacterial products containing TSST-1. These showed coarse granular cytoplasmic staining in proximal convoluted tubules with some diffuse nuclear staining. This pattern was not seen in controls injected with saline. These results indicate that TSST-1 might have a pathogenic role in some cases of SIDS.

Bacterial toxins: a possible cause of cot death.

AIM: To test the hypothesis that sudden infant death syndrome (SIDS) may be caused by toxins of commonly occurring bacteria in infants lacking developed immunity. METHODS: Nasopharyngeal microbial isolates from 22 pairs of SIDS cases and healthy infants matched for age (by month), sex, and sampling time (by month) were compared for lethal toxigenicity. Crude toxin preparations were made from isolates cultured on dialysis membrane overlaid on agar, and these preparations were then tested for lethality by intravenous injection into 11 day old chick embryos. RESULTS: Fifteen (68%) of the SIDS cases were each found to have at least one lethally toxigenic organism in their nasopharyngeal flora; only eight (36%) of the flora of normal infants included a lethally toxigenic species. CONCLUSION: Infants who have died of SIDS have a significantly higher (p less than 0.05) probability than matched healthy infants of having a lethally toxigenic bacterial species in their nasopharyngeal flora.

Age-related changes in binding to excitatory amino acid uptake sites in human cerebellum.

In vitro autoradiography and test-tube assay of the sodium-dependent binding of D-[3H]aspartate were used to localize and quantify the uptake site for the excitatory amino acid neurotransmitters glutamate and aspartate in the cerebellar cortex of human cerebellar hemispheres. Autoradiograms revealed a pronounced heterogeneity in the distribution of D-[3H]aspartate binding in cortex from adult brains, with the highest binding density corresponding to the Purkinje cell layer, high binding in molecular layer and low binding in granule cell layer. In contrast, cerebellar cortex from infants at term (40 weeks gestation) had only low binding of the ligand in both the molecular and the Purkinje cell layers. Both methods employed for measuring D-[3H]aspartate binding showed that the number of binding sites in Purkinje and molecular layers increased rapidly from term to 20 weeks postnatal age and achieved levels higher than those found in adult cerebellum. It is concluded that a substantial increase in the numbers of glutamate/aspartate uptake sites takes place in the human cerebellum during the early postnatal period. It is deduced that the excess uptake sites are eliminated as the cerebellum matures.

Preliminary investigation of lethally toxic sera of sudden infant death syndrome victims and neutralisation by commercially available immunoglobulins and adult sera.

The aim of the study was to test the hypotheses (i) that sudden infant death syndrome sera are toxic to 11-day old chick embryos and (ii) that such a toxicity can be counteracted by immunoglobulin or adult sera. Serum samples from 11 SIDS victims and five controls were tested for lethal toxicity in the chick embryo bioassay. Five serum samples were used to challenge chick embryos injected with the following: sudden infant death syndrome serum plus Hank's balanced salt solution; Hank's balanced salt solution alone; sudden infant death syndrome serum plus 3% w/v commercial immunoglobulin; sudden infant death syndrome serum plus 6% w/v immunoglobulin; sudden infant death syndrome serum plus pooled sera of 40 healthy adults. Results obtained revealed that Hank's balanced salt solution, the pooled adult serum and the commercial immunoglobulin were all non-lethal, in the chick embryo test system. By contrast. 10 sudden infant death syndrome victims yielded sera containing lethal levels of toxin(s) compared to 2/5 controls which was statistically significant (P < 0.05, Fischer's exact test). In the tests of sudden infant death syndrome serum plus immunoglobulin or pooled adult serum, the lethality of sudden infant death syndrome serum was abolished in all cases. The reduction in toxicity of individual sudden infant death syndrome serum plus immunoglobulin or pooled adult serum was often statistically significant (P<0.05-P<0.00005, Fischer's exact test). We conclude that lethal levels of toxin are present in sudden infant death syndrome sera and that they can be neutralised by normal immune serum. These results indicate that passive immunisation is a potential treatment to protect babies considered at risk from sudden infant death syndrome.

Endotoxin in blood and tissue in the sudden infant death syndrome.

Although the explanation for sudden infant death syndrome (SIDS) remains unknown, an increasing body of evidence now exists to suggest a possible role for bacterial toxins in the aetiology, and a number of investigators have considered that endotoxaemia could explain some of the associated features. Following the development of an animal model which confirmed that endotoxaemia could be detected after death, we studied endotoxin levels in blood and tissue samples taken at autopsy from SIDS infants, child controls and adult controls. There were significant correlations between endotoxin levels in blood and the various organs sampled particularly in SIDS cases and child controls, and blood endotoxin levels in SIDS cases were higher in those infants where there was histological evidence of mild to moderate inflammation. However, overall no significant differences were found between endotoxin levels in blood or tissue in the three study groups. Further studies into possible actions or interactions of endotoxin in SIDS are required.

Age-related changes in binding to excitatory amino acid uptake site in temporal cortex of human brain.

The binding of D-[3H]aspartate to the specific uptake site for the excitatory amino acids glutamate and aspartate was measured in homogenates of temporal lobe cortex taken at postmortem from 76 human infant and adult brains. Binding levels were very low in brains of preterm and term infants but increased rapidly during the first 20 postnatal weeks to reach levels which exceeded those in adult brains. Linear regression analysis which compared the amount of D-[3H]aspartate binding with the age of the infant, showed a positive correlation up to 25 postnatal weeks. Saturation analysis showed that the maximum number of D-[3H]aspartate binding sites (Bmax) in temporal cortex from infants aged 20 postnatal weeks was 3 times greater than the number of sites in adult brain. The findings show that the number of excitatory amino acid uptake sites, which may be associated in part with presynaptic terminals, increase in number rapidly after birth. Furthermore, the data may indicate that a slow regression of excitatory amino acid terminals occurs during the later stages of brain development.

The nasopharyngeal bacterial flora in the sudden infant death syndrome.

The nasopharyngeal bacterial flora in babies who had died of the sudden infant death syndrome (SIDS) (n = 46) and in healthy infants aged 2 weeks to 6 months (n = 46) is described. Of those who had died, 41.3% carried Staphylococcus aureus (95% confidence limits: 27.3-55.3%) compared with 28.3% of healthy infants (95% confidence limits: 15.3-41.3%). The isolation rate of streptococci was 78.3% in cases (95% confidence limits: 66.4-90.2%) and 32.6% in healthy infants (95% confidence limits: 19.1-46.1%) (significant difference P less than 0.0001). Enterobacteria were isolated from 45.6% of cases (95% confidence limits: 31.2-60%) but only 2.2% of healthy infants (95% confidence limits 0-6.4%) (significant difference, P less than 0.0001). These results indicate a disordered nasopharyngeal flora in SIDS. They also provide baseline data for investigating the hypothesis that common bacterial toxins are involved in the pathogenesis of SIDS.

Modulation by magnesium of N-methyl-D-aspartate receptors in developing human brain.

AIM: To investigate age related alterations in glutamate N-methyl-D-aspartate (NMDA) receptor binding produced by the modulatory compounds glutamate, glycine, and magnesium (Mg2+) sulphate. METHODS: The effects produced by glutamate plus glycine, and Mg2+ on the binding of [3H]MK-801, a ligand for the N-methyl-D-aspartate ion channel phencyclidine site, were measured in membrane preparations made from prefrontal cortex from human neonate (n = 5), infant (n = 6), and adult (n = 6) necropsy brains. RESULTS: Neonatal brains had the least [3H]MK-801 binding, suggesting either a low density of NMDA receptors or a more restricted access of [3H]MK-801 to cation channel sites. Infant brains had the most [3H]MK-801 binding which was stimulated to a greater extent by L-glutamate (100 microM) and glycine (10 microM) than in neonatal and adult brains. MG2+ invariably inhibited [3H]MK-801 binding. However, the Mg2+ IC50 value was higher in neonatal brain (3.6 mM) than infant (1.4 mM) and adult (0.87 mM) brains. CONCLUSION: Infant brain may have excess NMDA receptors which are hyper responsive to glutamate and glycine. The lower potency of Mg2+ to inhibit [3H]MK-801 binding in neonatal cortex may be because newborn babies have NMDA receptors without the normal complement of Mg2+ sites. The findings suggest that therapeutic NMDA receptor block in neonates requires higher concentrations of magnesium sulphate in brain tissue.

Pulmonary hypoplasia in a regional perinatal unit.

83 cases of pulmonary hypoplasia were found in 709 perinatal necropsies in St. Mary's Hospital between 1976 and 1983. 49 of these infants were inborn, representing an incidence of 1.4 per 1000 births. Diaphragmatic hernia was present in 43% and was the commonest reason for referral, usually to the neonatal surgical unit, from an outside hospital. Renal malformation, often with oligohydramnios, was seen in 25%, and 11% had no other major disease. The respiratory symptoms associated with pulmonary hypoplasia in the absence of diaphragmatic hernia seem to have encouraged the referral of these infants to the neonatal medical unit. However, more than half the liveborn infants with pulmonary hypoplasia died during the first postnatal day. In comparison with first week deaths from other causes, short survival was a particular feature of pulmonary hypoplasia in infants weighing less than 2.5 kg and pneumothorax and pulmonary haemorrhage were commoner in term infants with hypoplastic lungs.

Pulmonary surfactant. I. In immature and mature babies.

Lung surfactant was obtained by postmortem lavage from: (A) premature babies: 34 dying acutely within 2 days of birth from Hyaline Membrane Disease (HMD), 20 dying several days after birth with HMD and its consequences, 8 dying from causes other than HMD; (B) mature babies: 24 dying stillborn, 15 dying soon after birth and 16 dying between 2 weeks and 1 year of age with minimal lung pathology. The phospholipid composition of the surfactant was analysed. Compared to the surfactant of babies dying acutely from HMD, that of the babies dying later from HMD contained significantly higher proportions of phosphatidylcholine (PC) and significantly lower proportions of sphingomyelin while that of the mature babies contained significantly higher proportions of PC and phosphatidylglycerol but significantly lower proportions of sphingomyelin and combined phosphatidylinositol and phosphatidylserine. The surfactant of premature babies dying of causes other than HMD was similar and intermediate to that of both groups of babies dying from HMD. The PC fraction composition of the surfactant of the babies dying acutely from HMD contained significantly lower proportions of the disaturated fraction than those of the babies dying later from HMD, stillborn babies or mature babies.

Pulmonary surfactant. II. In sudden infant death syndrome.

The lung surfactant phospholipid composition of lavage samples from 102 babies dying from Sudden Infant Death Syndrome (SIDS) (one-third with minor signs of inflammation) was compared with that of: 34 babies dying from Hyaline Membrane Disease (HMD), 15 mature babies dying soon after birth, 16 mature babies dying in the same age range as the sudden infant death syndrome cases, 13 babies dying from pneumonia and 6 from septicaemia. The surfactant of the two groups of babies dying from SIDS was identical and approximated that obtained from babies dying from HMD, pneumonia or septicaemia. Compared to that obtained from mature babies, the surfactant of babies dying from SIDS contained significantly lower proportions of phosphatidylcholine (PC) and significantly higher proportions of lyso-PC and sphingomyelin. The proportion of disaturated PC was similar to that of the surfactant of the age-matched mature babies. The surfactant composition of the babies dying from SIDS did not change appreciably after death nor vary with age at death. The surfactant phospholipid composition of postmortem samples from mature babies was similar to that of aspirates from living babies and infants and to that of bronchoalveolar lavage samples from living adults.

The sensitivity of the developing tooth germ to systemic disturbances.

Deciduous tooth germs were removed from 76 babies who were either stillborn or had died in infancy. Lines in enamel or dentine were identified histologically. A chronological association was found between these lines and systemic illness in the child or pregnant mother in half the cases studied. Enamel was more sensitive to environmental factors than dentine, but causes of disturbance appeared to be non-specific. Teeth are a sensitive but non-specific index of environmental disturbance.

Physical and biochemical characteristics of the human dysraphic spinal cord.

The spinal cords were removed from 29 infants between 17 and 46 weeks gestation, all with various forms of spinal dysraphia. The spinal cords were assessed for weight, length, thickness, size and number of cells, and myelination, and then were compared with 86 control spinal cords. The strongest characteristic of the dysraphic cords was a reduced degree of myelination. Cell size and number generally were appropriate for the weight of the cords. There was a tendency for cord weight, length and thickness to be reduced, though in part this was a reflection of poor over-all bodily growth. In a small group of infants these measurements were increased in comparison with the controls.