Reliability of chest radiograph interpretation for pulmonary tuberculosis in the screening of childhood TB contacts and migrant children in the UK.

AIM: To determine interobserver agreement between paediatric radiologists interpreting tuberculosis (TB) screening chest radiographs (CXR) in children in the UK, and the TB detection rate. MATERIALS AND METHODS: A retrospective review was undertaken of electronic request, notes, and CXRs (>7 years) in children exposed to an infectious case of TB and new entrants to the UK, at a tertiary children's hospital. Included were those with positive Mantoux/interferon gamma release assay (IGRA), positive culture, or high clinical suspicion of TB. CXR reports were categorised as normal, abnormal without features of TB, or abnormal with features of pulmonary TB. Three paediatric radiologists from a dedicated paediatric radiology department evaluated available CXRs, aware of the TB screening indication, using a published CXR reporting tool and blinded to the initial CXR report and to each other. A majority decision was collated, and considered lymphadenopathy and miliary nodules as diagnostic of primary TB. Interobserver agreement was calculated using Cohen's kappa. RESULTS: One hundred and forty-eight children underwent TB screening with a CXR. One hundred and twenty-five had available CXR reports and case notes, which indicated 20/125 (16%) had CXR features of TB. One hundred and twenty-one of the 125 had CXRs available to for panel review. Twenty of these 121 (17%) yielded a majority decision of pulmonary TB. Inter-reader agreement was moderate in all aspects (kappa 0.4-0.6). CONCLUSION: The high percentage of pulmonary TB on CXR (16% original reports; 17% by panel review) suggests that it is worthwhile investigating childhood TB contacts; however, the routine use and recommendation for CXR is questionable because of only moderate interpretation reliability (kappa 0.5), even by experts.

Technical note: characterizing individual milk fat globules with holographic video microscopy.

We used in-line holography to create images of individual milk fat globules in diluted samples of milk. Analyzing these images with the exact Lorenz-Mie light scattering theory then yields the droplets' radii with nanometer resolution and their refractive indexes to within one part in a thousand. This procedure rapidly and directly characterizes both the quantity and quality of fat in milk.

Case report of a Wilms' tumor and a left-sided inferior vena cava. A common tumor with a normal variant of surgical significance.

We report a case of a successful surgical resection of a Wilms' tumor in the right kidney with a coincidental preoperative imaging finding of a left-sided inferior vena cava. To our knowledge, these 2 conditions occurring together has not been previously reported in literature. Diagnostic features and the value of magnetic resonance imaging are emphasized. We also review the literature of major venous anomalies and their influence on surgical procedures carried out on such patients.

The pathophysiology of HOX genes and their role in cancer.

The HOM-C clustered prototype homeobox genes of Drosophila, and their counterparts, the HOX genes in humans, are highly conserved at the genomic level. These master regulators of development continue to be expressed throughout adulthood in various tissues and organs. The physiological and patho-physiological functions of this network of genes are being avidly pursued within the scientific community, but defined roles for them remain elusive. The order of expression of HOX genes within a cluster is co-ordinated during development, so that the 3' genes are expressed more anteriorly and earlier than the 5' genes. Mutations in HOXA13 and HOXD13 are associated with disorders of limb formation such as hand-foot-genital syndrome (HFGS), synpolydactyly (SPD), and brachydactyly. Haematopoietic progenitors express HOX genes in a pattern characteristic of the lineage and stage of differentiation of the cells. In leukaemia, dysregulated HOX gene expression can occur due to chromosomal translocations involving upstream regulators such as the MLL gene, or the fusion of a HOX gene to another gene such as the nucleoporin, NUP98. Recent investigations of HOX gene expression in leukaemia are providing important insights into disease classification and prediction of clinical outcome. Whereas the oncogenic potential of certain HOX genes in leukaemia has already been defined, their role in other neoplasms is currently being studied. Progress has been hampered by the experimental approach used in many studies in which the expression of small subsets of HOX genes was analysed, and complicated by the functional redundancy implicit in the HOX gene system. Attempts to elucidate the function of HOX genes in malignant transformation will be enhanced by a better understanding of their upstream regulators and downstream target genes.

Sorting mesoscopic objects with periodic potential landscapes: optical fractionation.

Viscously damped objects driven through a periodically modulated potential energy landscape can become kinetically locked in to commensurate directions through the landscape, and thus can be deflected away from the driving direction. We demonstrate that the threshold for an object to become kinetically locked in to an array can depend exceptionally strongly on its size. When implemented with an array of holographic optical tweezers, this process provides the basis for a continuous and continuously optimized sorting technique for mesoscopic objects called "optical fractionation."

Imaging in haematopoietic stem cell transplantation.

Haematopoietic stem cell transplantation (SCT) is used to treat a wide range of malignant and non-malignant haematological conditions, solid malignancies, and metabolic and autoimmune diseases. Although imaging has a limited role before SCT, it is important after transplantation when it may support the clinical diagnosis of a variety of complications. It may also be used to monitor the effect of therapy and to detect recurrence of the underlying disease if the transplant is unsuccessful. We present a pictorial review of the imaging of patients who have undergone SCT, based upon 15 years experience in a large unit performing both adult and paediatric transplants.

Measuring a colloidal particle's interaction with a flat surface under nonequilibrium conditions. Total internal reflection microscopy with absolute position information.

A new and general approach is proposed to analyze the dynamics of a colloidal particle interacting with a nearby wall. This analysis can be used to determine the acting forces even when the system is non-stationary. As an illustration, we use total internal reflection microscopy to investigate the forces acting on a polystyrene sulfate latex particle as it is receding from a charged glass surface.

Sub-aponeurotic fluid collections in infancy.

AIM: To describe the radiological features and natural history of sub-aponeurotic fluid collections presenting after the neonatal period. MATERIALS AND METHODS: All cases of sub-aponeurotic scalp fluid collection presenting to the radiology department between June 1996 and June 2000 were reviewed. Note was made of the birth history, the radiographic and ultrasound features and the natural history (including any treatment) of the collection. RESULTS: Seven cases of sub-aponeurotic fluid collections were identified. There were six infants who presented 3.5-18 weeks (mean nine weeks) after delivery, four of whom had had ventouse-assisted delivery. The last case was in a seven-year-old child who presented one month after minor head trauma. Clinical examination revealed non-tender, soft, mobile and fluctuant scalp swellings in all patients. Ultrasound identified sonolucent fluid collections of between 5 and 24 mm depth in the sub-aponeurotic space. No skull fractures were identified. Six patients were treated conservatively and one had fluid aspirated and a compression bandage applied. All cases resolved 2-24 weeks after diagnosis and there were no long-term sequelae. CONCLUSION: Sub-aponeurotic scalp collections presenting after the neonatal period are usually associated with ventouse-assisted delivery ultrasound is useful for diagnosis. The condition is benign and resolution occurs with conservative treatment.

Imaging of malignant infantile osteopetrosis before and after bone marrow transplantation.

BACKGROUND: Malignant infantile osteopetrosis (MIOP) is a sclerosing bone disease caused by absence or defective function of osteoclasts. Since these are of haemopoietic origin, the disease can be cured by allogeneic stem-cell transplantation, but there are no detailed studies of radiological follow-up of these procedures. OBJECTIVE: To investigate the radiological findings at presentation and follow-up in children undergoing bone marrow transplantation (BMT) for MIOP. MATERIALS AND METHODS: Examination of the records and imaging studies of nine paediatric patients undergoing BMT for MIOP during 1988-2000. RESULTS: Presentation findings included characteristic features such as fractures, subperiosteal new bone formation and rachitic appearances. Five children engrafted successfully, allowing assessment of the nature and speed of resolution of radiological features after transplantation. CONCLUSIONS: Radiological improvement was apparent within 2 months of successful engraftment with almost complete resolution of abnormalities after 1 year. Studies in two children who are, respectively, 58 and 83 months post-transplant show complete resolution of all bone changes.

Pair interaction of charged colloidal spheres near a charged wall.

Although equally charged colloidal particles dispersed in clean water are expected to repel each other, an unexplained long-range attraction has consistently been reported for charged colloidal spheres confined by charged macroscopic surfaces. We present an alternative equilibrium measurement of the pair interaction energy for charged spheres near a single charged wall. Analyzing their radial distribution functions for different concentrations reveals a purely repulsive sphere-sphere interaction that is well described by a screened Coulomb potential.

Pneumatic dilatation for childhood achalasia.

Treatment of achalasia by pneumatic balloon dilatation (PBD) is well established in adults. Due to limited experience and the rarity of the condition in children, there are relatively few reports in the paediatric literature. Although PBD has been reported as a primary method of treatment, there are no reports of secondary PBD for childhood achalasia. Between 1995 and 1999, five patients underwent treatment for achalasia (age: 9-14 years, M:F = 4:1). The presenting symptoms were dysphagia (5). vomiting episodes (2), aspiration (1), food-bolus obstruction (1), and failure to thrive (1). In all patients a barium swallow and manometry were used to confirm the diagnosis. Three underwent primary PBD. Two who had previously undergone surgical myotomy underwent secondary PBD for recurrence of symptoms. Dilatation was performed using a 35-mm balloon with the child under general anaesthesia. Technical success was defined as demonstration of a waist under screening at lower pressures followed by abolition of the waist at higher pressures. In addition to reviewing our results, a systematic review of the literature was performed (Medline, Cochrane Library, Pubmed, Embase). Three patients (primary dilatation) showed excellent improvement after a single dilatation. In two cases (secondary dilatation) three and five attempts were required. No complications were encountered. The mean follow-up period was 2 years (1-3.5 years) and four patients remained asymptomatic, an overall success rate of 80%. The literature review revealed similar good results in most of the recent reports. Thus, PBD as a primary treatment for childhood achalasia has a success rate of 70%-90% with minimal side effects, short hospital stay, and good patient acceptability over an operation. We have also established the usefulness of this method as a secondary treatment when symptoms recur after surgery.

Mixed foregut cyst associated with esophageal atresia.

The authors report an unusual case of a thoracoabdominal foregut malformation with components of bronchogenic, esophageal duplication, and pancreatic enterogenous cysts, that presented in a child with esophageal atresia. J Pediatr Surg 36:939-940.

Human computers: the first pioneers of the information age.

Before computers were machines, they were people. They were men and women, young and old, well educated and common. They were the workers who convinced scientists that large-scale calculation had value. Long before Presper Eckert and John Mauchly built the ENIAC at the Moore School of Electronics, Philadelphia, or Maurice Wilkes designed the EDSAC for Manchester University, human computers had created the discipline of computation. They developed numerical methodologies and proved them on practical problems. These human computers were not savants or calculating geniuses. Some knew little more than basic arithmetic. A few were near equals of the scientists they served and, in a different time or place, might have become practicing scientists had they not been barred from a scientific career by their class, education, gender or ethnicity.

Hydrodynamic coupling of two brownian spheres to a planar surface.

We describe direct imaging measurements of the collective and relative diffusion of two colloidal spheres near a flat plate. The bounding surface modifies the spheres' dynamics, even at separations of tens of radii. This behavior is captured by a stokeslet analysis of fluid flow driven by the spheres' and wall's no-slip boundary conditions. In particular, this analysis reveals surprising asymmetry in the normal modes for pair diffusion near a flat surface.

Outcome and clinical course of 100 patients with adenovirus infection following bone marrow transplantation.

We conducted a retrospective review of the clinical features and outcome of adenovirus infection in 572 consecutive patients transplanted in a single centre over a 10 year period. One hundred patients (17%) had a total of 105 episodes of adenovirus infection diagnosed at a median of 18 days post transplant (range 2-150 days). The incidence was higher in children than adults (21% vs 9%, P < 0.001) and in unrelated donor vs matched sibling donor transplants (26% vs 9%, P < 0.001). Diarrhoea and fever were the most common presenting features. Reflecting these symptoms, the most common site of isolation was the stool. Serotypes 1, 2 and 7 were the most frequently seen (total of 41/68 or 60% of evaluable cases). In six patients (6%) adenovirus infection was the direct cause of death occurring at a median of 72 days post transplant (range 18-365 days). Five of these six patients had pulmonary involvement and four had associated graft-versus-host disease (GVHD). Three further patients were considered to have severe adenoviral disease (total incidence 9%). Isolation of virus from multiple sites correlated with a poor outcome (P < 0.001). Comorbid viral infection was common in this group with 50% of all patients having other viruses isolated (predominantly polyoma virus and cytomegalovirus). We conclude that adenovirus is commonly isolated after bone marrow transplant and is a cause of significant morbidity but was a rare cause of mortality (6/572 = 1%) in our patient group as a whole. The relative infrequency of severe infection will make it difficult for the transplant physician to decide which patients should receive experimental antiviral drugs such as ribavirin and cidofovir or immunomodulatory therapy with donor white cell infusions.

Pollen-stigma adhesion in Arabidopsis: a species-specific interaction mediated by lipophilic molecules in the pollen exine.

To investigate the nature and role of cell adhesion in plants, we analyzed the initial step of pollination in Arabidopsis: the binding of pollen grains to female stigma cells. Here we show this interaction occurs within seconds of pollination. Because it takes place prior to pollen hydration, it also requires adhesion molecules that can act in a virtually dry environment. We developed assays that monitored adhesion of populations of pollen grains and individual cells. Adhesion between pollen and stigma cells is highly selective - Arabidopsis pollen binds with high affinity to Arabidopsis stigmas, while pollen from other species fails to adhere. Initial binding is independent of the extracellular pollen coat (tryphine), indicating that adhesion molecules reside elsewhere on the pollen surface, most likely within the exine walls. Immediately after pollination, the stigma surface becomes altered at the interface, acquiring a pattern that interlocks with the exine; this pattern is evident only with pollen from Arabidopsis and its close relatives. Purified exine fragments bind to stigma cells, and biochemical analyses indicate that this specific, rapid and anhydrous adhesion event is mediated by lipophilic interactions.