Nuclear Magnetic Resonance Chemical Shift as a Probe for Single-Molecule Charge Transport.

Existing modelling tools, developed to aid the design of efficient molecular wires and to better understand their charge-transport behaviour and mechanism, have limitations in accuracy and computational cost. Further research is required to develop faster and more precise methods that can yield information on how charge transport properties are impacted by changes in the chemical structure of a molecular wire. In this study, we report a clear semilogarithmic correlation between charge transport efficiency and nuclear magnetic resonance chemical shifts in multiple series of molecular wires, also accounting for the presence of chemical substituents. The NMR data was used to inform a simple tight-binding model that accurately captures the experimental single-molecule conductance values, especially useful in this case as more sophisticated density functional theory calculations fail due to inherent limitations. Our study demonstrates the potential of NMR spectroscopy as a valuable tool for characterising, rationalising, and gaining additional insights on the charge transport properties of single-molecule junctions.

Reliability of lower extremity alignment measurement using radiographs and PACS.

PURPOSE: Lower extremity alignment is an important consideration prior to cartilage surgery and/or osteotomy about the knee. This is measured on full length standing hip to ankle radiographs, which has traditionally been done using hard copy radiographs. However, the advent of PACS (Picture Archiving and Communication Systems) has allowed these measurements to be done on computer based digital radiographs. The objectives of this study were to evaluate the intra- and inter-observer reliability of lower limb alignment measures manually obtained from hard copy radiographs versus using the Philips Easy Vision system, and to assess the subjective ease of use for the two methods. METHODS: Forty-two patients who underwent surgery and who had a standing hip to ankle radiograph on file were identified. Four raters, including two radiologists and two orthopaedic surgeons, measured each hard copy radiograph and computer image on two separate occasions. Three measurements were recorded for each hard copy radiograph and computer image-width of tibial plateau, the distance from the medial aspect of the tibial plateau to the weight-bearing line, and the mechanical axis. RESULTS: All correlations for this study were high. For tibial plateau data, the hard copy radiographs compared to PACS demonstrated intra-class correlation coefficients (ICC) ranging from 0.93 to 0.99 for inter-rater reliability for the four raters. The ICC for intra-rater reliability for hard copies ranged from 0.90 to 0.99 and for PACS from 0.94 to 0.99. The inter-rater data comparing raters ranged from 0.87 to 0.98 for hard copy radiographs and from 0.98 to 0.99 for PACS. For mechanical axis data, the ICC for hard copy radiograph compared to PACS ranged from 0.93 to 0.97 for the intra-rater reliability for the four raters. The intra-rater reliability for mechanical axis data on hard copy radiograph ranged from an ICC of 0.86 to 0.96, and for PACS the ICC ranged from 0.93 to 0.99. The inter-observer data for hard copy radiographs using the mechanical axis ranged from 0.88 to 0.94 and for PACS ranged from 0.93 to 0.97. The physicians rated PACS as statistically significantly easier to use when compared to hard copy (P = 0.03). CONCLUSION: Evaluation of lower extremity alignment using two techniques prior to knee surgery was found to have higher inter- and intra-observer reliability using PACS software. PACS is now used prior to cartilage surgery and/or osteotomy to measure both alignment and the location of the weight bearing line on the tibial plateau both before and after surgery. LEVEL OF EVIDENCE: Diagnostic study, Level I.

Structure determination and crystal chemistry of large repeat mixed-layer hexaferrites.

Hexaferrites are an important class of magnetic oxides with applications in data storage and electronics. Their crystal structures are highly modular, consisting of Fe- or Ba-rich close-packed blocks that can be stacked in different sequences to form a multitude of unique structures, producing large anisotropic unit cells with lattice parameters typically >100 Šalong the stacking axis. This has limited atomic-resolution structure solutions to relatively simple examples such as Ba2Zn2Fe12O22, whilst longer stacking sequences have been modelled only in terms of block sequences, with no refinement of individual atomic coordinates or occupancies. This paper describes the growth of a series of complex hexaferrite crystals, their atomic-level structure solution by high-resolution synchrotron X-ray diffraction, electron diffraction and imaging methods, and their physical characterization by magnetometry. The structures include a new hexaferrite stacking sequence, with the longest lattice parameter of any hexaferrite with a fully determined structure.

Photochemical CO2 reduction in water using a co-immobilised nickel catalyst and a visible light sensitiser.

A dye-sensitised CO2 reduction photocatalyst that operates in water is reported. Transient spectroscopy demonstrates that the facile co-immobilisation of a Ru dye and a Ni CO2 reduction electrocatalyst enables efficient on-particle electron transfer leading to photocatalytic activity that greatly exceeds the equivalent solution based system.

Eight-year school performance, neurodevelopmental, and growth outcome of neonates with bronchopulmonary dysplasia: a comparative study.

Eight-year outcome is reported for three groups of preterm infants with bronchopulmonary dysplasia--group 1 with a birth gestation of less than or equal to 31 weeks receiving supplemental oxygen until the equivalent of 36 weeks' gestation, group 2 of the same gestation receiving supplemental oxygen to 28 days postnatal age but not to 36 weeks gestational age, and group 3 with a gestation of greater than or equal to 32 weeks requiring supplemental oxygen for greater than 28 days--and for an individually matched preterm neonatal comparison group and a term peer comparison group for each bronchopulmonary dysplasia group. The subjects all had parents whose mother tongue was English and were matched for gender, mother's education, and father's socioeconomic status, and in the case of the neonatal comparison groups they also were matched for birth gestation and birth weight. Physical growth and psychoeducational and school performance test scores were similar for the three bronchopulmonary dysplasia study groups with the exception of lower intelligence quotient for those receiving supplemental oxygen for the longest time. Children in groups 1 and 2 had outcome scores similar to those of the neonatal comparison group and significantly below those of their peer comparison groups. On multivariate analysis for group 1 children, 61% of the variance of academic achievement was related to lowest recorded pH, father's socioeconomic status, and lowest recorded PaO2. Compared with the peer groups, the study groups continued to show academic delay when the disabled children were excluded from analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Population-based study of the incidence, complexity, and severity of neurologic disability among survivors weighing 500 through 1250 grams at birth: a comparison of two birth cohorts.

Mortality and incidence, complexity, and severity of early childhood neurodevelopmental disability are reported for two cohorts of preterm infants of 500 through 1250 g birth weight. Comparing 1978-1979 (cohort 1) and 1988-1989 (cohort 2), 1-year survival improved from 82 (36%) of 226 to 197 (67%) of 291. Cohort 1 survivors were heavier and more mature than cohort 2 survivors (1047 g vs 930 g, 29.6 vs 27.3 weeks). Parental demographic variables were similar. The incidence of specific disabilities with greater than 97% follow-up to 1.5 years adjusted age did not change: cerebral palsy, 14 (17%) vs 20 (10%); vision loss, 5 (6%) vs 9 (5%); mental retardation, 9 (11%) vs 13 (7%); hearing loss, 3 (4%) vs 7 (4%); and convulsive disorders, 2 (2%) vs 3 (2%). The overall number of disabled children (17 [21%] vs 30 [15%]), complexity of disability (> or = 2 disabilities per child: 11 [13%] vs 10 [5%]), and severity of disability (projected dependency: 6 [7%] vs 10 [5%]) did not differ between cohorts 1 and 2. The cerebral palsy prevalence, based on neonatal survival, dropped from 157 per 1000 to 93 per 1000. Analysis by birth weight-specific categories in 250-g increments did not alter results, but disability rates were highest for those of lowest weight. In contrast to other reports this population-based North American study from a well-developed perinatal regional program reports no increase in incidence, complexity, or severity of disability in preterm infants weighing 500 through 1250 g at birth.

Province-based study of neurologic disability of children weighing 500 through 1249 grams at birth in relation to neonatal cerebral ultrasound findings.

BACKGROUND: Adverse neurodevelopmental outcome in premature infants is more common in the presence of certain ultrasonographically detectable intracranial lesions. Present nomenclature and classifications of parenchymal changes in preterm infants of varying gestations have led to some confusion. Descriptive definitions may be clinically useful. Regionalized perinatal and neonatal care enables population-based studies of these lesions and subsequent outcomes. METHODS: Two- to 3-year outcomes of neonates weighing 500 through 1249 g born in Alberta to Alberta residents during 1987 through 1990 were reviewed in relation to neonatal cerebral ultrasound lesions. Odds ratios and confidence limits for disability were calculated. RESULTS: Of 960 live births in this weight group, 669 (70%) survived to 1 year adjusted age; 646 (96.6%) were assessed at follow-up, and 80 (12.4%) of these were disabled: cerebral palsy, 8.7%; vision loss, 2.9%; hearing loss, 1.3%; epilepsy, 0.6%; mental retardation, 4.8%; more than one disability per child, 3.6%; and projected dependent disability, 1.4%. Lesions considered to be predictive of disability on ultrasound (excluding germinal layer hemorrhage) were found in 79 (11.8%), parenchymal lesions in 63 (9.4%) of 1-year survivors: intraventricular hemorrhage (IVH) (n = 59), persistent or transient cerebral ventriculomegaly (n = 50), persistent or transient intraparenchymal periventricular echodensity (n = 29), and cystic periventricular leukomalacia (n = 7). All lesions except isolated IVH were associated with adverse outcome; 37% of disabled children, 61% of multiply disabled children, and all children projected to become dependently disabled had parenchymal lesions with or without IVH. Triple lesions of IVH, cerebral ventriculomegaly, and intraparenchymal periventricular echodensity gave an odds ratio for disability of 50. Transient lesions had significant risk. CONCLUSIONS: This province-based study provides a descriptive scheme of serial neonatal cerebral ultrasound lesions and outcome considered useful for clinicians caring for newborns of lowest gestational ages. The overall incidence of parenchymal lesions was lower than frequently reported. Combinations of lesions were linked to increased incidence, complexity, and severity of childhood disability.

EEG and long-term outcome of term infants with neonatal hypoxic-ischemic encephalopathy.

OBJECTIVE: The prognostic value of a burst suppression pattern (BSP) on the electroencephalograph (EEG) in the prediction of long-term outcome for full term newborns with hypoxic-ischemic encephalopathy (HIE) is well established. The purpose of our study was to compare the patterns of burst suppression on EEG with long-term neurological outcome in term infants with HIE. METHODS: We retrospectively analyzed all records of all full-term newborn infants born at the University of Alberta Hospital between January 1, 1991 and December 31, 1992, who had clinical evidence of HIE and had at least one EEG during the first week of life. The EEGs were reviewed and blindly subclassified into a BSP, or if the pattern was not continuous or was incomplete, a modified burst suppression pattern (MBSP), based on specified electrophysiological criteria. The long-term neurological outcome was then correlated with the EEG pattern. RESULTS: Twenty-three full-term infants were studied. Fifteen had a BSP on EEG and 8 had a MBSP. Six of 15 infants with a BSP died. Of the 9 survivors with a BSP, 7 are disabled and two are normal. Of the 8 infants in the MBSP group, one infant died, two are disabled and 5 are normal. In the BSP group, 6/7 disabled infants developed cerebral palsy while in the MBSP group, only one developed cerebral palsy. CONCLUSION: The results are suggestive of a better outcome for infants with neonatal HIE and MBSP on EEG compared with those with a BSP. Subclassification of the EEG changes of neonatal HIE into BSP and MBSP may give a more accurate prediction of outcome in perinatal asphyxia and assist in discussion with parents about prognosis.

Early childhood neurodevelopment in very low birth weight infants with predischarge apnea.

Apnea commonly occurs in preterm infants and may persist beyond term. We prospectively investigated the relationship between apnea that persisted beyond 35 weeks post-conceptional age and subsequent neurodevelopment in early childhood. Between January, 1990-November, 1993, we performed predischarge respiratory recordings, using 24-hr, 4-channel pneumography, at 35 weeks or more of postconceptional age in 164 infants (birth weight, <1,250 g; gestational age, < or = 32 weeks), who subsequently underwent multidisciplinary neurodevelopmental assessment at 15-64 (median 24) months of adjusted age. The duration of initial artificial ventilation for respiratory distress syndrome and the grade of intraventricular hemorrhage were independent predictors of neurodevelopmental outcome. Mean oximetry desaturation and frequency of predischarge apnea correlated with mental and motor developmental scores. Mean oximetry desaturation during apnea was an independent predictor for motor score in the total population, and for both mental and motor scores in 50 infants with grade 3 or 4 intraventricular hemorrhage, but not in 114 infants without grade 3 or 4 intraventricular hemorrhage. Despite its limited predictability for early childhood neurodevelopment, predischarge respiratory recordings may be useful in predicting subsequent neurodevelopment of high-risk preterm infants, especially those with severe intraventricular hemorrhage.

Plasma lactate as a predictor of early childhood neurodevelopmental outcome of neonates with severe hypoxaemia requiring extracorporeal membrane oxygenation.

Although plasma lactate concentration has been widely used as an indicator of tissue hypoxia, no clinical study has been conducted to relate these values to the neurological outcome of sick neonates. Seventeen consecutively cared for and surviving neonates with severe hypoxaemia requiring extracorporeal membrane oxygenation (ECMO) were evaluated at a mean age of 19.6 months. The serial plasma lactate concentrations were significantly correlated with the scores of the Bayley Scales of Infant Development. Admission and peak plasma lactate of < or = 15 mmol/l predicted favourable outcome (MDI and PDI > 70 and no disability): sensitivity 100%, specificity 88%, positive predictive value 90%, and negative predictive value 100%. Plasma lactate values could help predict neurodevelopmental outcome in these sick neonates.

Prevalence of cerebral palsy in Alberta.

BACKGROUND: In spite of scattered reports to the contrary, concern is continually expressed that the frequency of cerebral palsy has not decreased with modern perinatal/neonatal care. Overall, epidemiological information on cerebral palsy is scant. The generally accepted prevalence is 2 to 2.5 per thousand school-age children. METHODS: A population-based record linkage study of a presently living cohort of 96,359 children born from April, 1985 through March, 1988 and followed over an eight-year tracking period captured the diagnostic codes for all fee-for-service physician claims, all hospital separations and individual birth data from the Department of Vital Statistics of the Government of Alberta. The ICD-9 code "343" was used to identify subjects. The childhood prevalence and frequency by birthweight-specific sub-groups of cerebral palsy after age three years (congenital, 229 [92.3%]; probable acquired 19 [7.7%]) were identified giving an overall prevalence of 2.57 per 1000. Seventy percent were diagnosed before their third birthday. Cohort prevalence of cerebral palsy for low birthweight children (< 2500 grams) was 17.7, very low birthweight (< 1500 grams), 78.5; and extremely low birthweight (< 1000 grams), 98.4. Low birthweight children made up just over one-third of cases in this study. CONCLUSIONS: Cerebral palsy continues to affect a significant number of children suggesting the prevalence of cerebral palsy has not decreased. The proportion of affected children with low birthweight in this study is less than that reported in the literature.

Outcome of shunted posthemorrhagic hydrocephalus in premature infants.

Patient histories of 29 infants were reviewed whose birth weights were less than 2,000 gm and who had received ventricular shunts in the neonatal period for posthemorrhagic hydrocephalus. This procedure was performed at a time when routine screening of low birth weight infants for intracranial hemorrhage was not undertaken and serial lumbar puncture usually was not employed. The overall outcome was poor, with 62% of shunted infants either dying or surviving with moderate or severe handicap. Neurodevelopmental outcome was associated with the interval between the diagnosis of hydrocephalus and shunting; an adverse outcome was associated with an increased interval. Current practices for treating posthemorrhagic hydrocephalus are discussed.

Neonatal encephalopathy: an indicator of early sexual maturation in girls.

Of 161 girls with neonatal encephalopathy who were prospectively assessed until 8 years of age, 7 (4.3%) demonstrated variable degrees of early sexual maturation. This finding was significantly greater than the accepted 0.6%, estimated for the general population. Four of the 7 girls with early sexual maturation had physical disabilities (i.e., 3 with cerebral palsy, 1 neurosensory deafness) which indicated that 10% of the 40 physically disabled girls had early sexual maturation. Three (2.5%) of 121 girls without physical disabilities matured early. Sexual maturation began 5 years or longer after the diagnosis of neonatal encephalopathy. An increased incidence of early sexual maturation in girls with neonatal encephalopathy indicates the importance of long-term follow-up of this population. This study provides an indication of a link between newborn illnesses causing neonatal encephalopathy and early sexual maturation in girls without progressive, structural, intracranial pathology and suggests further study of some girls previously diagnosed as having idiopathic precocious puberty.

Sensorineural hearing loss in survivors of neonatal extracorporeal membrane oxygenation.

From February 1989 to January 1994, nine of 63 (14.3%) survivors of neonatal extracorporeal membrane oxygenation developed bilateral sensorineural hearing loss. Seven of nine children were tested and passed initial or repeat clinical auditory brainstem response evaluation completed before discharge from neonatal intensive care. Hearing loss was suspected and confirmed between 6-36 and 10-48 months of age, respectively. We recommend regular audiologic follow-up for these high-risk infants until bilateral thresholds for hearing can be obtained.

Long-term follow-up of term neonates with perinatal asphyxia.

Available evidence shows adverse sequelae do not follow perinatal asphyxia unless encephalopathy is part of the neonatal clinical presentation. Where neonatal encephalopathy follows evidence of late fetal and/or early neonatal distress, the staging of the encephalopathy is useful for determination of prognosis; those with mild encephalopathy do well; those with severe encephalopathy do poorly. We believe this staging could be made more universally useful as an outcome variable for study of the etiology and timing of perinatal hypoxic-ischemic injury as well as for prediction of long-term outcome, if clinical correlates to pathophysiologic hypoxic-ischemic insults were used more broadly as the basis for defining the staging criteria. Most survivors of perinatal asphyxia do not have adverse sequelae, and later cognitive development has been shown to be similar to normative data. Although survivors of mild or severe encephalopathy have a predicted outcome, the outcome of those with moderate (Stage 2) hypoxic-ischemic encephalopathy is less certain; however, these children are at risk for neurologic disability and future academic failure. Prediction equations with good specificity for school-readiness outcome of the nondisabled survivors of moderate encephalopathy have been established allowing for early discharge from follow-up for those children predicted to do well. Mean school-age psychoeducational test results show nondisabled moderate encephalopathy survivors have scores below those in the mild encephalopathy group as well as below comparison groups, particularly for tests involving the auditory pathway, attention, and short-term recall; it is not known if these delays will resolve with time. School-aged nondisabled moderate encephalopathy survivors did not show the perceptual-motor delay reported in younger survivors. Overall, tests used to evaluate subtle changes that may relate to perinatal hypoxic-ischemic injury have been inadequate; future studies should include tests of acquisition of new learning, memory, problem solving, and reasoning. Further research is required to define the nature and timing of perinatal insults and the continued function of survivors.

Educational readiness of survivors of neonatal encephalopathy associated with birth asphyxia at term.

Standardized individual psychoeducational school-readiness tests were completed by 127 nondisabled survivors of moderate (lethargy, hypotonia, and suppressed primitive reflexes) or mild (hyperalertness, hyperexcitibility) neonatal encephalopathy associated with term birth asphyxia. Application of the readiness test battery to the children with moderate or mild encephalopathy and a peer population, revealed that children with moderate encephalopathy had significantly lower scores for many tests than those in the other groups. Children with mild encephalopathy performed well. We found no significant differences due to social variables. For the moderate group, we found an increased number of types of anticonvulsants and abnormal findings on the neurologic examination at neonatal intensive care unit (NICU) discharge to be predictors of low achievement on school-readiness tests. Also for the nondisabled moderate group, multiple regression analysis of the independent variables with the 5.5-year scores added variables suggestive of intrauterine growth retardation to the prediction of lower scores on many school-readiness tests. We conclude that clinical categorizing of moderate neonatal encephalopathy associated with birth asphyxia in term infants selects a group of children with an increased percentage of school-readiness delay, and could be a useful indicator for clinicians and educators in defining those neonates who may need special preschool evaluation and benefit from a modified early school program.

Carotid artery reconstruction in neonates receiving extracorporeal membrane oxygenation: a 4-year follow-up study. Western Canadian ECMO Follow-Up Group.

Although venoarterial extracorporeal membrane oxygenation (ECMO) is an accepted form of cardiopulmonary support for critically ill neonates, carotid artery reconstruction (CAR) after decannulation remains controversial. Long-term follow-up information regarding the natural progression of the anastomosis is unavailable. From January 1990 through December 1990, 13 venoarterial neonatal ECMO survivors had CAR performed and were enrolled into this prospective study based on sonographic follow-up of CAR. A total of 34 carotid artery sonographic studies were performed (13 within 1 week after reconstruction, 8 at 6 to 9 months, and 13 at 4 years of age). A high patency rate during the neonatal period was observed (12 of 13, 92%). Among 12 children with normal neonatal sonographic studies, 5 had completely normal studies during 4 years of follow-up. Narrowing at the anastomotic site (defined as structural narrowing with velocity ratio of peak systolic velocity at the anastomosis to peak systolic velocity proximal to the anastomosis > 1.0 but < or =2.0) by 4 years of age developed in 7 children. Two of these 7 children had hemodynamically significant stenotic anastomosis (defined as structural narrowing with velocity ratio >2.0) by 4 years of age. One neonate had a narrowed anastomosis that resolved completely by the age of 4 years. The incidence of normal studies decreased from 92% to 75% to 46% during the neonatal period, at 6 to 9 months, and at 4 years follow-up, respectively (Chi-square test for trend, P < .01). Long-term follow-up information on the natural progression of carotid reanastomosis is required.

Validation of prediction of kindergarten-age school-readiness scores of nondisabled survivors of moderate neonatal encephalopathy in term infants.

Outcome studies of nonmalformed term infants with neonatal encephalopathy associated with late fetal and/or early neonatal distress show those in the severe category die or become disabled; 18% in the moderate category become disabled and of the nondisabled, greater than 40% have school-readiness delay. Predictive indices for kindergarten-age learning ability obtained from obstetrical/neonatal and family/social data were developed for 71 nondisabled survivors of moderate neonatal encephalopathy born in 1974-79 (Cohort I). Predicted outcome was compared to actual outcome of a second cohort of neonates with the same diagnosis, born in 1982-86 (Cohort II); comparison groups for both cohorts were tested. School-readiness scores from Cohort II were similar to Cohort I and both were below respective comparison groups. Prediction for the nondelayed was 68% to 95%; for the delayed 7% to 29%, affected by the lower sample size available for this category. Predicted scores were within 0.5 SD of actual scores for 80% of not delayed children. Nondisabled survivors predicted to do very well can be discharged from follow-up; others with moderate or severe neonatal encephalopathy should receive ongoing assessment.

The development of a neonatal stool colour comparator.

The policies which exist to monitor the passage of neonatal stool vary between and within hospitals. When stool colour is required, the recorded observations are invariably subjective opinions and as such are largely unreliable. The development of a stool colour comparator allowed an objective test to be used by professional staff and mothers. This facilitated data collection for a study which sought to determine, among other factors, the transition time of meconium through to the yellow stool of the milk-fed baby, during the early neonatal period. The transition time of the meconium is indicative of gastrointestinal activity in the newborn and midwives are able to correlate accurately documented changes in stool colour with the baby's daily weight loss to assess the quality and/or adequacy of early infant feeding particularly breast feeding. The stool colour comparator is used in postnatal wards at Ninewells Hospital, Dundee by mothers and midwives and the numerical coding has replaced the previously used subjective abbreviations Mec (Meconium), Ch (Changing) and Y (Yellow).

Relationships between baby feeding types and patterns, gut transit time of meconium and the incidence of neonatal jaundice.

The incidence of neonatal jaundice is reported to have increased in relation to breast feeding and various factors are thought to contribute to this either singularly or in concert. In a group of 150 full-term healthy babies, feeding types and gut transit time of meconium were examined. The findings demonstrated significant differences between feeding types and time taken to evacuate total meconium (p < 0.0001), weight loss/gain patterns (p < 0.0005) and the incidence of moderately severe jaundice (p < 0.01) during the early neonatal period. Baby feeding types were clearly defined in the study and a stool colour comparator was used to facilitate identification and classification of all stool colour transition from meconium through to yellow. Maximum weight loss was found to occur on the second day after delivery and in many instances the lost weight was regained by the baby on the fifth day. Exceptions to this were babies who fed ineffectively or inadequately. These outcomes suggest that the assistance and advice given to mothers and babies, by midwives and others, to achieve effective feeding practices in the days following birth is of paramount importance to the baby's immediate wellbeing.