Cytotoxicity assessment of some carbon nanotubes and related carbon nanoparticle aggregates and the implications for anthropogenic carbon nanotube aggregates in the environment.

Nanotechnology and nanomaterials have become the new frontier world-wide over the past few years and prospects for the production and novel uses of large quantities of carbon nanotubes in particular are becoming an increasing reality. Correspondingly, the potential health risks for these and other nanoparticulate materials have been of considerable concern. Toxicological studies, while sparse, have been concerned with virtually uncharacterized, single wall carbon nanotubes, and the conclusions have been conflicting and uncertain. In this research we performed viability assays on a murine lung macrophage cell line to assess the comparative cytotoxicity of commercial, single wall carbon nanotubes (ropes) and two different multiwall carbon nanotube samples; utilizing chrysotile asbestos nanotubes and black carbon nanoaggregates as toxicity standards. These nanotube materials were completely characterized by transmission electron microscopy and observed to be aggregates ranging from 1 to 2 microm in mean diameter, with closed ends. The cytotoxicity data indicated a strong concentration relationship and toxicity for all the carbon nanotube materials relative to the asbestos nanotubes and black carbon. A commercial multiwall carbon nanotube aggregate exhibiting this significant cell response was observed to be identical in structure to multiwall carbon nanotube aggregates demonstrated to be ubiquitous in the environment, and especially in indoor environments, where natural gas or propane cooking stoves exist. Correspondingly, preliminary epidemiological data, although sparse, indicate a correlation between asthma incidence or classification, and exposure to gas stoves. These results suggest a number of novel epidemiological and etiological avenues for asthma triggers and related respiratory or other environmental health effects, especially since indoor number concentrations for multiwall carbon nanotube aggregates is at least 10 times the outdoor concentration, and virtually all gas combustion processes are variously effective sources. These results also raise concerns for manufactured carbon nanotube aggregates, and related fullerene nanoparticles.

Rapid prenatal diagnosis of Patau's syndrome in a fetus with an abdominal wall defect by 72 hour culture of cells from amniotic fluid.

A woman in the 32nd week of pregnancy was referred for investigation because of fetal abnormalities, including an abdominal wall defect, detected by ultrasonography. In view of the increased risk of chromosome abnormality, amniocentesis was performed to enable informed decisions about the management of the pregnancy and delivery to be taken. Cells from the liquor were inoculated into standard lymphocyte culture medium and incubated for 72 h. Slides with a high mitotic index and good quality metaphases, comparable to those from a blood culture, were obtained after harvesting. Cytogenetic analysis showed the karyotype to be 46,XY, - 14,+t(13q14q), which is consistent with Patau's syndrome. This technique appears to be an option for rapid karyotyping in cases of abdominal wall defect, where a chromosomal abnormality is suspected.

Congenital defects and the care of low birthweight infants.

Proportions of infants of birthweight 501-2000 g born in 1979-1981 who had defects recognisable at birth were ascertained by examining hospital records and tracing survivors. Twenty-seven per cent of 230 stillbirths, 8.4% of 1411 livebirths, 4.5% of 1117 neonatal survivors and 3.6% of 1074 two-year survivors had a congenital defect, birth prevalence rising with lower birthweight only in stillbirths. Among livebirths, birth prevalence was increased in growth retarded infants, in singletons and in infants of mothers who had not had a previous reproductive loss. Twenty-four per cent and 57% of neonatal deaths in the 1001-1500 g and 1501-2000 g birthweight groups respectively were associated with a congenital defect. Major neurological impairments were directly attributable to congenital defects in 10% of 71 survivors; surgery and hospital admissions were far more frequent in infants with congenital defects than others. The 1501-2000 g group accounted for 77% of all survivors with a congenital defect. Further improvements in the prognosis of low birthweight infants will depend to a large extent on prenatal prevention of disease.

Cerebral palsy in low-birthweight infants. I. Spastic hemiplegia: associations with intrapartum stress.

Children with and without spastic hemiplegia were identified among a representative sample of 1048 low-birthweight survivors by clinical assessment after three years of age. The hypothesis that hemiplegia was predetermined at birth was tested by estimating the probability of hemiplegia for each infant by logistic regression analysis, using data from hospital records on conditions known at the time of birth. 16 of 42 children with cerebral palsy had spastic hemiplegia. Allowing for the lower birthweights of hemiplegic children, increased prevalence was associated with previous reproductive loss, breech vaginal delivery, later birth-order, prolonged second stage of delivery, emergency caesarean section, and low Apgar scores. These variables identified correctly most children as having a higher or lower estimated probability of hemiplegia. Hemiplegia was also associated with prolonged respiratory disease and intraventricular haemorrhage. In this population it is likely that intrapartum events were closely related to the pathogenesis of hemiplegia; their effects may have been mediated by postnatal events.

Cerebral palsy in low-birthweight infants. II. Spastic diplegia: associations with fetal immaturity.

Twenty children with spastic diplegia were identified by clinical assessment among a representative cohort of 1048 survivors with a birthweight of 2000g or less. Data from hospital case-records were used to investigate which perinatal conditions might differentiate infants with diplegia from other low-birthweight survivors. Even allowing for a strong association with lower gestational age, diplegic children were more likely to have suffered respiratory disease, necrotising enterocolitis and fits in the neonatal period, than children without cerebral palsy. Among preterm infants, diplegia differed from hemiplegia mainly in a lack of significant association with recorded maternal characteristics and markers of intrapartum stress. Important determinants of diplegia were not identified, but the results suggest that infants born both immature and relatively immature for their gestational age have the highest risk of diplegia. Factors that influence the rate of fetal development may be implicated in the aetiology of diplegia in both preterm and fullterm infants.

Regional neonatal intensive care: bias and benefit.

Among very low birthweight infants born to residents of Merseyside in 1979-81 those booked at or transferred in utero to the regional unit were more likely to survive than those born elsewhere in the region. A study was carried out to determine whether the increased survival rate was attributable to better care or differences in the babies treated at the unit, or both. Four subpopulations were defined by district of maternal residence to obtain fairly comparable samples. Survival to 2 years increased as proportions treated at the regional unit increased, this "dose-response" effect being most pronounced among the smallest infants. Despite less favourable social state infants from the district housing the regional unit were apparently in the best condition at birth; had been managed most actively before, at, and after birth; and were the most likely to survive. This increased survival, however, was associated with a marginally significant increase in prevalence of major impairments. These data underline the need for routine surveillance of large representative samples of low birthweight survivors.

Epidemiology of strawberry haemangioma in low birthweight infants.

The prevalence of cutaneous haemangiomas in a representative population of low birthweight infants was determined by tracing and assessing survivors of pre-school age. Data from hospital case-notes and follow-up assessments were used to investigate whether prevalence of haemangiomas was related to perinatal factors and childhood morbidity. Eleven point one per cent of 615 infants developed a haemangioma. Haemangiomas were more common in girls than boys, and in infants of lower gestational age. Hypothermia in the first hours of life and neonatal illness were associated with lower prevalence, suggesting that neonatal skin perfusion influences haemangioma development; this is consistent with a tendency for haemangiomas to be distributed centripetally. However, the major aetiological determinants are unknown. Children with a haemangioma were more likely to have had a febrile convulsion than those without a haemangioma.

Why do so many small infants develop an inguinal hernia?

Prevalence and incidence of inguinal hernia in a representative sample of low birthweight survivors were determined by tracing children at 3 years of age. Prevalence was examined in relation to perinatal factors recorded in hospital case notes, using a logistic regression model to allow for confounding variables. Of the 1074 two year survivors, 995 (93%) were assessed. Seventeen per cent of 497 boys and 2% of 498 girls had a hernia by 3 years of age, a total cumulative prevalence of 9.2%: it was significantly increased by lower birth weight, male sex, neonatal intravenous feeding, and lack of respiratory disease. Neonatal illnesses were otherwise not associated with herniation, and most infants were well when they presented. Peak incidence was at the expected full term of gestation. Bilateral hernias were increasingly more common than unilateral hernias at lower gestational ages. It is proposed that causes of increased abdominal pressure in healthy neonates are important causes of herniation during a critical period of inguinal development.

Survival and morbidity in a geographically defined population of low birthweight infants.

Rates of survival and of neurological impairment in a geographically defined population of low birthweight infants born during 1979-1981 were determined by tracing infants and assessing survivors at pre-school age. Comparison with data from similar studies relating to earlier years shows that the proportion of low birthweight infants who survive with no major impairment has increased significantly; the risk of surviving with an impairment has not altered sufficiently for a significant difference to be apparent from these comparisons.

Precipitation of sulfide ores and organic matter: sulfate reactions at pine point, Canada.

Bitumen is a common associate of carbonate-hosted lead-zinc deposits. On the Pine Point lead-zinc property, Northwest Territories, Canada, there are two forms of bitumen. Unaltered bitumens have atomic hydrogen/carbon ratios of about 1.4, sulfur contents of about 7.8 percent, and sulfur isotope ratios ( section sign(34)S) of approximately +4.6 per mil. Altered bitumens occur in proximity to sulfide ore bodies and white sparry dolomite. Their hydrogen/carbon ratios are about 1.02, the sulfur contents average 22 percent, and the section sign(34)S values are about +12.4 per mil. These data indicate that some bitumen has participated in the thermochemical reduction of sulfate to produce hydrogen sulfide required to precipitate the ores. Mass balance considerations show that the amount and degree of alteration of bitumen is more than adequate to account for the reduced sulfur species (lead, zinc, and iron sulfides) deposited at Pine Point. These reactions may provide an important means of generating the large volumes of sulfide necessary to precipitate ore bodies in carbonate rocks.

Fate of infants with transposition of the great arteries in relation to balloon atrial septostomy.

The palliation afforded by balloon atrial septostomy to 124 infants with transposition of the great arteries was assessed in terms of survival to 6 months of age without the need for further intervention. Prediction of success or failure in relation to palliation was significantly affected by the presence of associated ventricular septal defect, left ventricular outflow tract obstruction, or persistent ductus arteriosus and by the maximum volume of balloon used to perform the septostomy. There was a significant association between balloon volume and size of atrial defect found at subsequent surgery or necropsy.

The use of chloral hydrate for refractory childhood epilepsy.

Two children with refractory epilepsy, including life-threatening status epilepticus, are reported. In both cases the seizures responded to chloral hydrate.