Three-dimensional pulsed field gradient NMR measurements of self-diffusion in anisotropic materials for energy storage applications.

Anisotropic battery electrodes that allow enhanced diffusion through the thickness of the electrode can be engineered to improve the rate performance, but direct measurement of 3D diffusion in this pore structure is extremely challenging. To address this, we used 1H and 7Li pulsed field gradient (PFG) NMR to measure anisotropic diffusion in a model porous silicon substrate. We show that NMR spectroscopy can resolve solvent molecules and ions (here, in H2O, DMSO, and the battery electrolyte LIPF6:DC:EMC) in and outside of the pores of the Si substrate, allowing the diffusion coefficients of the ion/molecules in the two components to be individually determined. Exchange between ions/molecules inside and outside of the pores is observed with 1H 2D exchange spectroscopy (EXSY). The pore dimensions can extracted from the diffusivity of the in-pore component and the results are in reasonable agreement with the pore dimensions measured with electron microscopy. Better agreement is obtained for pore diameters; for pore length measurements, exchange between the in-pore and ex-pore solvents should be accounted for. These results suggest that PFG-NMR can serve as a non-destructive characterisation method for both in situ and ex situ analyses of materials ranging from complex battery and supercapacitor electrodes to catalyst supports and tissue scaffolds.

The genetic dynamics of the rapid and recent colonization of Denmark by Arion lusitanicus (Mollusca, Pulmonata, Arionidae).

We describe the genetic dynamics of the recent establishment of the 'Iberian slug', Arion lusitanicus J. Mabille 1868, in Denmark and compare its population structure to two other members of the 'large Arion complex', Arion ater ater, native to Denmark, and Arion ater rufus, introduced into Denmark in the early 1900s. Assaying allozyme polymorphism at seven enzyme loci, we found that: (1) None of the three taxa reproduce primarily by self-fertilization. Differences among loci and colonies in the pattern of deviation from Hardy-Weinberg equilibrium are most consistent with isolate mixing and perhaps with low amounts of selfing. (2) For both A. lusitanicus and A. a. rufus, gene diversity is lower in Danish colonies than in southern German colonies, implying population bottlenecks in the establishment of Danish colonies. (3) Significant linkage disequilibrium values usually involve the same three loci, viz. PGI, MDH-1 and MDH-2, suggesting physical linkage among these loci. (4) For both A. a. rufus and A. lusitanicus, the overall gene frequencies from Denmark and southern Germany are homogeneous, while variation among colonies within these regions ranges from around 15 to 28% for the three taxa. This indicates strong, local population genetic subdivision but with little restriction to gene flow from possible source areas. The heterogeneity in measures of diversity and differentiation indicates that population structure for all three taxa is dominated by ongoing founder effects, local extinction/colonisation dynamics, and genetic drift processes.

Concentration-dependent effects of the esterase inhibitor BNPP on macrophage migration and myelin phagocytosis.

Wallerian degeneration of a peripheral nerve is mainly characterized by axon and myelin degradation and is paralleled by a massive invasion of peripheral macrophages into the nerve. These cells enter the nerve attracted by a cascade of chemokines and cytokines but require proteolytic and enzymatic factors which enables them to cross the blood-nerve barrier. Here we investigated whether alpha-naphthyl (alpha-NA) esterases -- which have been shown to be exclusively expressed in human monocytes -- play a role during Wallerian degeneration. These enzymes were blocked by the specific inhibitor bis(4-nitrophenyl)-phosphate (BNPP) in an established in vitro model of Wallerian degeneration. Sciatic nerve segments of mice were co-cultured with peritoneal macrophages and BNPP was added to the cultures in various concentrations and at different timepoints. The macrophage numbers and myelin density in the nerve segments and the myelin load of macrophages were evaluated. After BNPP treatment the macrophage number within the nerve was significantly diminished and the myelin load within the macrophages was decreased, resulting in elevated levels of preserved myelin within the nerves. These experiments clearly showed a double effect of the alphaNA esterase inhibitor BNPP on macrophages. First, it suggests a role for alphaNA esterases on the migratory potential of macrophages since their invasion into the nerves was diminished. Second, the reduced myelin uptake is due to the inhibition of phagocytic capacity of these cells by BNPP. The therapeutical use of this inhibitor for treatment of autoimmune diseases such as multiple sclerosis or Guillain-Barré syndrome remains to be investigated.

Cognitive failure to thrive in high-risk infants: the importance of the psychosocial environment.

We evaluated early social risk assessment as a predictor of cognitive development in high-risk infants. A social worker assessed social risk in 122 infants before discharge from a neonatal intensive care unit. Infants were evaluated at ages 12 and 36 months adjusted for prematurity. We found no difference in 12-month cognitive development among medical, neurologic, or social risk groups. However, from 12 to 36 months there was a significant decline in mean developmental quotient in the groups with social risk alone, neurologic and social risk, and medical and social risk, but not in the groups with medical or neurologic risks without social risk. Social risk assessment correctly predicted 36-month cognitive outcome in 71% of infants who had normal findings at 12 months. We conclude that neonatal social risk assessment can help identify infants at highest risk for cognitive retardation and is particularly important for infants who have medical or neurologic problems.

Predictors of the home environment of high-risk infants.

The quality of the home environment is an important predictor of the cognitive and social development of high-risk infants. Community health nurses (CHNs) have played a central role in the assessment and care of families with high-risk infants. We examined predictors of the home environment in a sample of 106 infants discharged from a neonatal intensive care unit. The most consistent predictor of an optimal home environment was an internal parental locus of control. Socioeconomic status affected dimensions of parenting related to cognitive stimulation but not emotional responsivity. Young mothers and those with other children are less responsive to their infants. Males are treated in a more responsive manner than females. These findings suggest that CHNs need to adopt an empowerment model of intervention and focus on the particular needs of young mothers and those with other children.

Validation of key Denver Developmental Screening Test items: a preliminary study.

Three sequential studies were undertaken to identify a subset of 39 key Denver Developmental Screening Test (DDST) items covering the ages from birth to 6 years. The first study used binary integer programming with a sample of 2343 children evaluated with the DDST in Denver's Neighborhood Health Program. It identified 35 DDST items that would identify 100% abnormal and 97.9% abnormal and questionable DDSTs. A further validation with 113 Pitt County, North Carolina, children indicated that the addition of four more DDST items to the previous 35 would identify 100% abnormal and 92.6% abnormal and questionable DDSTs. A third study cross-validating the 39 items with a sample of 180 children at "high risk" identified 100% abnormal and 91.7% abnormal and questionable DDSTs. The 39 key DDST items ranged throughout the entire age span and among the DDST's four sectors. Use requires the administration of approximately four items at any one age, on average. Those children with suspect scores on the key DDST items (about 19% of a low-income population) should be screened with the remainder of the DDST to decrease overreferrals. For accuracy, the key DDST items must be administered in the manner prescribed in the DDST manual.

Cerebrospinal fluid lactate dehydrogenase in neonatal intracranial hemorrhage.

Cerebrospinal fluid (CSF) lactate dehydrogenase (LDH) was measured in 54 neonates with intracranial hemorrhage and compared with 82 control, 27 traumatic lumbar puncture, seven meningitis, and 30 asphyxiated newborns. Hospital data, neonatal outcomes, and long-term neurodevelopmental follow-up results were reviewed. CSF LDH was not significantly affected by traumatic lumbar puncture but was elevated in proportion to the severity of CNS hemorrhage as scored by computerized tomography. LDH was also significantly associated with subsequent seizures and hydrocephalus and abnormal long-term developmental outcome.

Plasma prostaglandin E2 and F2 alpha in preterm infants: association with respiratory distress syndrome and patent ductus arteriosus.

In order to determine if prostaglandin values correlate with gestational age, birth weight, postnatal age, or respiratory distress syndrome (RDS), we determined plasma prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E2 (PGE2) by specific radioimmunoassay in 34 samples from 27 preterm infants. Neither prostaglandin correlated with gestational age or with birth weight. PGF2 alpha decreased (p less than 0.3) with postnatal age. Values for PGF2 alpha and PGE2 in each sample varied together (p less than .01) but only PGF2 alpha increased (p less than .09) in infants with RDS. The highest PGF2 alpha values occurred in infants with severe RDS, including four infants with patent ductus arteriosus (PDA). In contrast, plasma PGE2 was not elevated in infants with RDS or PDA.

Postextubation nasal continuous positive airway pressure. A prospective controlled study.

Nasal continuous positive airway pressure (N-CPAP), applied immediately after extubation, was prospectively evaluated in 18 neonates recovering from respiratory distress syndrome. Patients were randomly assigned to N-CPAP (group 1, N=9) or a control group given oxygen by hood (group 2, N=9). Groups were comparable in birth weight and duration of intubation. In the 24-hour period following extubation, group 1 showed a significantly lower mean respiratory rate (46 +/- 2 vs 74 +/- 4), alveolar-arterial oxygen gradient (94 +/- 9 vs 134 +/- 12 mm Hg), PCO2 (45 +/- 1 vs 50 +/- 1 mm Hg), higher pH (7.33 +/- 0.01 vs 7.30 +/- 0.01), and less atelectasis by roentgenographic scores. This was associated with considerably better clinical courses in group 1 when compared with group 2, in which six patients required a late trial of N-CPAP because of respiratory deterioration and two patients needed reintubation. Postextubation N-CPAP has a striking beneficial effect on respiratory function and prevention of atelectasis.

Sodium balance in very low-birth-weight infants.

Sodium balance was studied in 17 consecutively admitted neonates weighing less than 1,200 gm at birth. Infants whose gestation was less than or equal to 30 weeks were sicker and were in markedly negative sodium balance on day 3 (-9.25 mEq/kg day), despite a high sodium intake (7.22 mEq/kg/day). This negative balance was the result of a high fractional sodium excretion and resulted in hyponatremia in six (50%) of the patients. By day 8 these immature infants were in positive sodium balance, although fractional sodium excretion and daily sodium requirements remained high. More mature infants (greater than 30 weeks gestational age) were in positive sodium balance on both days 3 and 8. Creatinine clearance did not differ significantly between groups on either day 3 or 8 but increased within each group during the study period. These data suggest that the daily sodium requirement of immature sick infants may be much higher than was previously suggested.