Improved Performance of Organic Light-Emitting Transistors Enabled by Polyurethane Gate Dielectric.

Organic light-emitting transistors (OLETs) are multifunctional optoelectronic devices that combine in a single structure the advantages of organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs). However, low charge mobility and high threshold voltage are critical hurdles to practical OLET implementation. This work reports on the improvements obtained by using polyurethane films as a dielectric layer material in place of the standard poly(methyl methacrylate) (PMMA) in OLET devices. It was found that polyurethane drastically reduces the number of traps in the device, thereby improving electrical and optoelectronic device parameters. In addition, a model was developed to rationalize an anomalous behavior at the pinch-off voltage. Our findings represent a step forward to overcome the limiting factors of OLETs that prevent their use in commercial electronics by providing a simple route for low-bias device operation.

Biosecurity and vaccination strategies to minimise the effect of an equine influenza outbreak on racing and breeding.

Three biosecurity and relief-and-recovery initiatives adopted by the NSW horse racing industries reduced the economic and social disruption caused by the disease and subsequent movement controls during the 2007 Australian equine influenza (EI) incursion. The first was the creation of biosecure horse training and racing precincts around the Sydney area to permit racing to continue with healthy horses. Infection was excluded for 3-5 weeks and race meetings were conducted safely during this period. The second was a vaccination program of racehorses at these and other precincts to maintain an ongoing healthy pool of racehorses. Vaccination commenced too late to enable viable racing to continue in Sydney in the short term, but assisted in managing an early return to racing throughout the state before EI-free status had been regained. The third was the establishment of approved quarantine stations to facilitate the movement of racing and breeding horses out of high-risk regions. The difficulties in establishing and managing these initiatives in the face of the EI incursion are discussed.

Handlebar hernia masquerading as an inguinal haematoma.

We report a child who sustained a traumatic hernia of the lower abdominal wall after being thrown forward against the handlebar of his bicycle. This is a rare injury in children, and the clinical features mimic an inguinal haematoma. Suspicion should be raised by the immediate appearance of a mass above the inguinal canal following groin injury, particularly if the swelling then disappears with the patient supine.

Magnetic resonance imaging of the infant brain: anatomical characteristics and clinical significance of punctate lesions.

OBJECTIVE: To describe the magnetic resonance imaging (MRI) characteristics of punctate brain lesions in neonates (number, appearance, distribution, and association with other brain abnormalities) and to relate them to neurodevelopmental outcome. METHODS: A retrospective analysis was performed of 110 MRI brain scans from 92 infants admitted in 1998 to the neonatal intensive care unit. Results of routine neurodevelopmental follow up (1998-2001) in those infants with punctate brain lesions were analysed. RESULTS: Punctate lesions were observed in 15/50 preterm and 2/42 term infants. In the preterm group, the number of lesions was < 3 in 20%, 3-10 in 27%, and > 10 in 53%. In 14/15 the lesions were linearly organised and located in the centrum semiovale. Other brain abnormalities were absent or minor--that is, "isolated" punctate lesions--in 8/15 and major in 7/15. In the term group, punctate lesions were organised in clusters and no other brain abnormalities were observed. Isolated punctate lesions were observed in 10/17 infants, and a normal neurodevelopmental outcome was seen in 9/10 (mean follow up 29.5 months). One infant showed a slight delay in language development. In the infants with associated brain lesions (7/17, mean follow up 27.5 months), outcome was normal in only two subjects. CONCLUSIONS: Punctate lesions are predominantly seen in preterm infants, are usually linearly organised, and border the lateral ventricles. Isolated punctate lesions may imply a good prognosis, because most of these subjects have a normal neurodevelopmental outcome so far.

Limitations and uses of gastrojejunal feeding tubes.

BACKGROUND: Gastrostomy feeding is a well established alternative method to long term nasogastric tube feeding. Many such patients have gastro-oesophageal reflux (GOR) and require a fundoplication. A transgastric jejunal tube is an alternative when antireflux surgery fails, or is hazardous or inappropriate. AIMS: To review experience of gastrojejunal (G-J) feeding over six years in two regional centres in the UK. METHODS: Retrospective review of all children who underwent insertion of a G-J feeding tube. RESULTS: There were 18 children, 12 of whom were neurologically impaired. G-J tubes were inserted at a median age of 3.1 years (range 0.6-14.7) because of persistent symptoms after Nissen fundoplication (n = 8) or symptomatic GOR where fundoplication was inappropriate. Four underwent primary endoscopic insertion of the G-J tube; the remainder had the tube inserted via a previous gastrostomy track. Seventeen showed good weight gain. There was one insertion related complication. During a median follow up of 10 months (range 1-60), four experienced recurrent aspiration, bilious aspirates, and/or diarrhoea. There were 65 tube related complications in 14 patients, necessitating change of the tube at a median of 74 days. Jejunal tube migration was the commonest problem. Five died from complications of their underlying disease. CONCLUSIONS: Although G-J feeding tubes were inserted safely and improved nutritional status, their use was associated with a high rate of morbidity. Surgical alternatives such as an Roux-en-Y jejunostomy may be preferable.

Primary papillary hyperplasia of the gallbladder: a rare cause of biliary colic.

Primary papillary hyperplasia of the gallbladder is a rare, poorly defined, clinicopathologic entity in adults. The authors describe a 12-year-old girl with this finding in the neck and body of the gallbladder. She presented with biliary colic, and ultrasonography of the gallbladder showed persistent thickening of the gallbladder wall but no evidence of calculi. Her symptoms resolved completely after cholecystectomy.

Cerebral maturation in premature infants: quantitative assessment using MR imaging.

BACKGROUND AND PURPOSE: The assessment of whether brain development is at an appropriate level for age has become an integral part of clinical MR reporting, although few studies have quantitatively defined the developmental changes occurring in premature infants. We have developed a simple scoring system to assess four parameters of cerebral maturation--myelination, cortical folding, glial cell migration, and germinal matrix distribution--to determine the total maturation score (TMS). The aim of this study was to validate this scoring system in a large population of preterm infants across a range of gestational ages. METHODS: A retrospective analysis was conducted of MR images acquired over a 3-year period with an identical imaging protocol. Infants born more than 14 days before the imaging examination and those with a clinical or radiologic history suggestive of neuroabnormality were excluded from the study. The TMS was derived by consensus. Interobserver agreement was evaluated by using the Bland-Altman plot. RESULTS: Images from 134 infants (23-41 weeks' gestational age) were evaluated. The TMS was significantly related to the postmenstrual age of the infant, with the mean TMS for each age group increasing with advancing postmenstrual age. Interobserver agreement was found to be high (mean difference in score = 0.07, SD = 0.56). CONCLUSION: This scoring system provides a standardized method for assessing cerebral maturation in the premature infant. The TMS is easy to calculate from standard MR images, is reproducible, and can help detect changes occurring within a postnatal age of a few weeks.

Magnetic resonance and cranial ultrasound characteristics of periventricular white matter abnormalities in newborn infants.

OBJECTIVE: To characterize the range of abnormalities within the periventricular white matter (PVWM) in a cohort of newborns using magnetic resonance (MR) brain imaging and to compare the focal MR abnormalities with the cranial ultrasound (CUS) findings. METHODS: Retrospective study of MR brain and CUS findings of infants born in the 18-month period 1998-1999. PVWM abnormalities were identified by MR and focal lesions were characterized by size, number and distribution using a grading scale. Correspondence with CUS findings was assessed. RESULTS: 175 MR examinations corresponding to n = 105 preterm infants, (median GA 28, range 23-36 weeks) and n = 25 term infants (median GA 39, range 37-42 weeks) were analysed for PVWM abnormalities. In the preterm group, MR demonstrated a normal PVWM in n = 76, focal areas of altered signal intensity (SI) in PVWM in n = 26 and venous infarction in n = 3. In the term group, MR demonstrated a normal PVWM in n = 15, focal areas of altered SI in PVWM in n = 4, oedematous PVWM in n = 2 and a middle cerebral artery infarction in n = 4. All infants with normal MR had normal CUS findings. A focal PVWM SI abnormality detectable on MR corresponded with an abnormality on CUS in only n = 10/30. CONCLUSIONS: MR appears considerably more sensitive than CUS in demonstrating the existence and extent of focal PVWM lesions in newborn infants. Satisfactory correspondence between the two imaging investigations is obtained only for cystic PVWM lesions.

Quantitative comparison of intrabrain diffusion in adults and preterm and term neonates and infants.

OBJECTIVE: Quantitative measurements of mean water diffusivity (D(av)) were made in human neonates, infants, and adults to assess changes in brain tissue that occur with maturation. SUBJECTS AND METHODS: Values of D(av) were obtained by calculating the average of the diffusion measurements made with diffusion-sensitizing gradients placed along three orthogonal directions. The mean diffusivity, a rotationally invariant determination of apparent diffusion coefficient, was measured in five healthy prematurely born neonates and infants, in 10 healthy term neonates and infants, and in five adults. RESULTS: Values of D(av) were found to decrease with maturation in most parts of the brain. In prematurely born neonates and infants with a postmenstrual age (postgestastional age + postnatal age) under 36 weeks, the average value of D(av) in frontal white matter was 1.90 x 10(-3) mm2 sec(-1). The corresponding value was measured as 1.62 x 10(-3) mm2 sec(-1) in neonates and infants born at term with a postnatal age of no more than 43 days and 0.79 x 10(-3) mm2 sec(-1) in the adult brain. CONCLUSION: Values of D(av) are known to decrease in neonates and young infants in the period immediately after ischemic insult. This decrease and the associated increase in signal intensity seen on diffusion-weighted imaging have been used to monitor ischemic brain injury in neonates and infants. Therefore, the decrease in D(av) that occurs with maturation, which we report in this study, must be considered if quantitative diffusion measurements are used to assess ischemic neonatal brain injury.

Limited ileal resection in infancy: the long-term consequences.

BACKGROUND/PURPOSE: The longer-term sequelae of short bowel syndrome in infancy are reasonably well documented, but little is known about the long-term nutritional and metabolic effects of limited (less than 50 cm) ileal resection. This makes it difficult to formulate a rational follow-up policy in such children. METHODS: All children who underwent limited ileal resection for either necrotizing enterocolitis (NEC) or intussusception at our institution between 1984 and 1992 were invited to attend a detailed clinical, anthropometric, hematologic, and biochemical assessment, together with a biliary and renal ultrasound scan and measurement of bone mineral density. RESULTS: Twenty-four children (NEC, 17; intussusception, 7) of median age 7.4 years (range, 5.5 to 13.7 years) agreed to participate. Nine previously had undergone an isolated ileal resection, and 15 also had had variable lengths of colon removed. The length of resected ileum ranged from 3 to 44 cm, with a median of 10 cm. Seven control subjects in whom neonatal NEC developed but recovered without surgery were also evaluated. Median height, weight, and body mass index after ileal resection were between the 25th and 50th percentiles; no child was stunted or wasted. After ileal resection, one boy was found to have asymptomatic vitamin B12 deficiency, and three children had low plasma concentrations of vitamin A. Hematologic and biochemical parameters were otherwise normal apart from a few marginally low trace element levels in both subjects and controls. No renal calculi were detected, and bone mineral density measurements were normal in all except one child. Four children had cholelithiasis, all of whom had previously undergone limited ileal resection for NEC (two isolated, two ileocolic). Thus, the prevalence of cholelithasis after limited ileal resection for NEC was 24% at a median age of 7.0 years. CONCLUSIONS: Growth and nutritional status are well preserved after limited ileal resection in infancy. Limited ileal resection for NEC is associated with a subsequent high prevalence of cholelithiasis and a risk of vitamin B12 deficiency. These findings are important when planning strategies for long-term follow-up.

Ionising radiation from diagnostic x rays in very low birthweight babies.

AIM: To quantify the exposure of very low birthweight neonates to ionising radiation from diagnostic x-rays. METHODS: Retrospective analysis was made of all radiographs performed over 18 months in an integrated special care baby unit and regional neonatal surgical unit in a large teaching hospital of surviving inborn babies of very low birthweight (< 1500 g) admitted to the unit. RESULTS: Fifty five VLBW neonates were treated for a total of 3296 days and received 498 radiographs (median 5 per infant). The mean effective radiation dose was 0.04 mSv and the maximum for one infant was 0.54 mSv. CONCLUSIONS: The radiation burden in this group of neonates is low and the benefits of diagnostic radiographs far outweigh any potential radiation risks.

Pancreatic exocrine and endocrine function after pancreatectomy for persistent hyperinsulinaemic hypoglycaemia of infancy.

AIM: To evaluate long term detailed pancreatic endocrine and exocrine function in children with persistent hyperinsulinaemic hypoglycaemia of infancy (PHHI) after 85-95% pancreatectomy. METHODS: Six children with PHHI between 0.9 and 12.7 years after pancreatic resection underwent clinical and investigative follow up at 1.0 to 14.9 years of age. One child with PHHI who had not had pancreatectomy was also assessed. Standard endocrine assessment, pancreatic magnetic resonance imaging (MRI), and detailed direct and indirect tests of exocrine pancreatic function were performed. RESULTS: Pancreozymin-secretin stimulation test results were normal in only one child, borderline in two, and deficient in four, one of whom requires daily pancreatic enzyme supplements. Pancreolauryl tests performed in three children were borderline in two and abnormal in the other. Only one child had low faecal chymotrypsin values. One child developed insulin dependent diabetes at 9 years and two children at 1.0 and 13.3 years require diazoxide to maintain normoglycaemia. MRI showed no major regrowth of the pancreatic remnant after resection (n = 5). CONCLUSIONS: Clinical evidence of endocrine or exocrine dysfunction has developed in only two patients to date, but detailed pancreatic function testing suggests subclinical deficiency in all but one of our patients with PHHI. Although 95% pancreatectomy results in postoperative control of blood glucose, subclinical pancreatic insufficiency is present on long term follow up and development of diabetes mellitus and exocrine failure remain ongoing risks.

Gastroschisis: a radiological and clinical review.

A retrospective clinico-radiological review was undertaken of 66 consecutive cases of gastroschisis managed at our institution between August 1982 and February 1993. The condition's morbidity and mortality were reviewed, as were its radiological features and their impact upon management. All patients underwent surgery in the first 24 h of life, and the overall survival rate was 92 %. The finding of bowel atresia at operation was associated with a particularly poor outcome, with only two out of five infants surviving. A minority of infants developed serious complications including necrotizing enterocolitis, short-bowel syndrome, persistent small-bowel dysfunction and cholestatic jaundice. Investigation by plain films, contrast studies and ultrasound examinations was necessary and helpful in these patients. Plain film radiography commonly revealed bowel-wall thickening and luminal dilatation, frequently accompanied by generalised abdominal distension. Small-bowel enema was considered to be superior to the conventional follow-through in distinguishing mechanical from functional obstruction in infants with persistent bowel dilatation.

Ruptured splenic epidermoid cyst: case report and imaging appearances.

Traumatic rupture of a splenic epidermoid cyst is a rare but recognised cause of "acute abdomen" in a child. We describe such a case occurring after very minor trauma, show the influence that imaging had in making an accurate diagnosis, and discuss how this influenced clinical management.

Enteric fistulas and necrotizing enterocolitis.

The incidence, presentation, significance, and outcome of infants with internal enteric fistula formation secondary to necrotizing enterocolitis (NEC) were examined. Of 130 infants with NEC treated during a 7-year period, an enteric fistula developed in five (4%). The gestational age of these patients (3 boys, 2 girls) ranged from 25 to 40 weeks and their birth weight ranged from 800 to 3,460 g. Two had Down's syndrome. Plain abdominal radiographs showed widespread intramural gas in all, and portal vein gas in two. Four patients required early laparotomy, which confirmed extensive intestinal necrosis; a diverting jejunostomy or ileostomy was constructed in three, and the abdomen was closed with drainage in one. Fistulas were diagnosed by contrast radiology between 16 and 51 days after the onset of NEC, and were jejunocolic (2), ileocolic (2), and colocolic (1). They were associated with enteric stricture(s), an inflammatory mass, and clinical signs of intermittent sepsis. One infant with an ileocolic fistula died of sepsis before definitive surgical treatment. Of the four who underwent surgery, two survived after limited intestinal resection, but one of the two with short bowel syndrome died. Enteric fistula formation is a rare complication of NEC. Typically it occurs with colonic stricture(s) and is associated with signs of incomplete bowel obstruction and intermittent sepsis. Resectional surgery is successful, but there appears to be a significant risk of short bowel syndrome.

Fetal pelvi-ureteric junction obstruction: predictors of outcome.

OBJECTIVE: To examine the relationship between pre-natal ultrasonographic findings typical of pelvi-ureteric junction (PUJ) obstruction and post-natal renal function in the affected kidney. PATIENTS AND METHODS: This retrospective study comprised 35 infants in whom pre-natal ultrasonography had identified a unilateral pattern of dilatation of the renal pelvis and calices typical of PUJ obstruction. In each case, the presence of unilateral hydronephrosis had been confirmed post-natally by ultrasonography, and differential function and drainage evaluated by isotope renography. The results of isotope renography were compared with the severity and timing of onset of the fetal hydronephrosis. RESULTS: Eleven kidneys (31%) appeared normal in the second trimester and dilatation only became apparent during the third trimester. Mean differential function in these kidneys was 48%. However, mean differential function was reduced (mean 38%) in those kidneys noted to be dilated between 16 and 24 weeks gestation. Differential function was loosely correlated with the severity of dilatation in early onset cases, i.e. the mean differential function was 42% for mild, 37% for moderate and 27% for severe dilatation. A considerable variation in differential function values was present in each group except for those with severe dilatation, which was a significant predictor of poor functional outcome when compared with mild and moderate dilatation combined (P < 0.01). CONCLUSION: Fetal PUJ obstruction is a heterogeneous condition permitting only broad predictions of functional outcome. Severe dilatation detected on second trimester imaging predicted significant loss of function. Mild and moderate degrees of dilatation were associated with a one in three risk of functional impairment in the obstructed kidney.

Prenatally detected posterior urethral valves: is gestational age at detection a predictor of outcome?

Between 1982 and 1992, 67 boys with posterior urethral valves were managed at our hospital, including 32 (48%) in whom the condition was detected prenatally. We examined the relationship between gestational age at detection and outcome at a median followup of 3.9 years (range 4 months to 10 years). Detection at or before 24 weeks of gestation predicted a poor outcome with 9 of 17 patients (53%) dead or in chronic renal failure at followup. Of the cases detected later in pregnancy only 1 had a poor outcome (p = 0.01). All of the cases detected after 24 weeks of gestation had had normal second trimester scans. Growth parameters for boys in the early and late detection groups were not statistically different. However, there was a significant association between renal failure and growth with 67% versus 14% having heights less than the 3rd percentile (p = 0.05). Respiratory distress at birth predicted a poor outcome, while the presence of palpable abdominal abnormalities or vesicoureteral reflux failed to predict outcome.

Mild dilatation of the fetal kidney: a follow-up study.

OBJECTIVE: To assess morbidity in children with mild prenatally detected pelvicalyceal dilatation and to document the natural history of this ultrasound finding in post-natal life. PATIENTS AND METHODS: A retrospective (on-going) study was carried out in 29 children (39 kidneys) with mild dilatation confined to the pelvis and/or calices confirmed on initial post-natal ultrasound scan. Re-evaluation was carried out at a mean age of 4.2 years (range 1.5-7.8). Clinically, each patient's history, height, weight and blood pressure were recorded. On ultrasound examination the renal length, collecting system appearances and dimensions were recorded. RESULTS: Vesico-ureteric reflux was demonstrated in 1 of 14 infants who underwent neonatal micturating cystourethrography. During cumulative follow-up totaling 122 years, there were only two documented episodes of urological morbidity, i.e. one episode of unexplained haematuria and one of urinary tract infection. By a mean age of 4.2 years the ultrasound appearances had reverted to normal in 69% of kidneys. In 31% dilatation persisted and was unchanged or diminished in severity. No case of increasing dilatation was seen. Renal growth was normal in 97% of kidneys. CONCLUSIONS: Mild dilatation of the fetal urinary tract is a common prenatal ultrasound finding. When confined to the renal pelvis and/or calices it is of doubtful clinical significance and is associated with a low level of morbidity in infancy and early childhood. Invasive investigation in post-natal life is not justified.