Measurement of the Lambda0b lifetime in the decay lambda0b--> J/psiLambda0 with the D0 detector

We present measurements of the Lambda(0)(b) lifetime in the exclusive decay channel Lambda(0)(b)--> J/psiLambda(0), with J/psi--> mu(+)mu(-) and Lambda(0)--> ppi(-), the B0 lifetime in the decay B0-->J/psiK(0)(S) with J/psi--> mu(+)mu(-) and K(0)(S)-->pi(+)pi(-), and the ratio of these lifetimes. The analysis is based on approximately 250 pb(-1) of data recorded with the D0 detector in pp collisions at sqrt[s] = 1.96 TeV. The Lambda(0)(b) lifetime is determined to be tau(Lambda(0)(b)) = 1.22(+0.22)(-0.18)(stat) +/- 0.04(syst) ps, the B0 lifetime tau(B0) = 1.40(+0.11)(-0.10)(stat) +/- 0.03(syst) ps, and the ratio tau(Lambda(0)(b))/tau(B0) = 0.87(+0.17)(-0.14)(stat) +/- 0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Lambda(0)(b) lifetime based on a fully reconstructed decay channel.

Search for Wbb and WH production in pp collisions at square root [s]=1.96 TeV

We present a search for Wbb production in pp collisions at sqrt[s]=1.96 TeV in events containing one electron, an imbalance in transverse momentum, and two b-tagged jets. Using 174 pb(-1) of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on Wbb production of 6.6 pb for b quarks with transverse momenta p(b)(T)>20 GeV and bb separation in pseudorapidity-azimuth space DeltaR(bb)>0.75. Restricting the search to optimized bb mass intervals provides upper limits on WH production of 9.0-12.2 pb for Higgs-boson masses of 105-135 GeV.

Search for the flavor-changing neutral current decay B0s--> mu(+) mu(-) in pp Collisions at sqrt[s] = 1.96 TeV with the D0 detector

We present the results of a search for the flavor-changing neutral current decay B(0)(s)--> mu(+) mu(-) using a data set with integrated luminosity of 240 pb(-1) of pp collisions at sqrt[s] = 1.96 TeV collected with the D0 detector in run II of the Fermilab Tevatron collider. We find the upper limit on the branching fraction to be B(B(0)(s)--> mu(+) mu(-)) < or= 5.0 x 10(-7) at the 95% C.L. assuming no contributions from the decay B(0)(d)--> mu(+) mu(-) in the signal region. This limit is the most stringent upper bound on the branching fraction B(0)(s)--> mu(+) mu(-) to date.

Search for supersymmetry with gauge-mediated breaking in diphoton events at D0

We report the results of a search for supersymmetry (SUSY) with gauge-mediated breaking in the missing transverse energy distribution of inclusive diphoton events using 263 pb(-1) of data collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2004. No excess is observed above the background expected from standard model processes, and lower limits on the masses of the lightest neutralino and chargino of about 108 and 195 GeV, respectively, are set at the 95% confidence level. These are the most stringent limits to date for models with gauge-mediated SUSY breaking with a short-lived neutralino as the next-to-lightest SUSY particle.

Measurement of the B0s lifetime in the exclusive decay channel B0s-->J/psiphi

Using the exclusive decay B0s-->J/psi(mu+mu-)phi(K+K-), we report the most precise single measurement of the B0s lifetime. The data sample corresponds to an integrated luminosity of approximately 220 pb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2004. We reconstruct 337 signal candidates, from which we extract the B0s lifetime, tau(B0s)=1.444(+0.098)(-0.090)(stat)+/-0.020(sys) ps. We also report a measurement for the lifetime of the B0 meson using the exclusive decay B0-->J/psi(mu+mu-)K*0(892)(K+pi-). We reconstruct 1370 signal candidates, obtaining tau(B0)=1.473(+0.052)(-0.050)(stat)+/-0.023(sys) ps, and the ratio of lifetimes, tau(B0s)/tau(B0)=0.980(+0.076)(-0.071)(stat)+/-0.003(sys).

Observation and properties of the X(3872) decaying to J/psipi(+)pi(-) in pp collisions at sqrt[s]=1.96 TeV

We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in pp collisions at sqrt[s]=1.96 TeV. Using approximately 230 pb(-1) of data collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.

Search for doubly charged higgs boson pair production in the decay to mu(+)mu(+)mu(-)mu(-) in pp collisions at sqrt[s]=1.96 TeV

A search for pair production of doubly charged Higgs bosons in the process pp -->H(++)H(--) -->mu(+)mu(+)mu(-)mu(-) is performed with the D0 run II detector at the Fermilab Tevatron. The analysis is based on a sample of inclusive dimuon data collected at an energy of sqrt[s]=1.96 TeV, corresponding to an integrated luminosity of 113 pb(-1). In the absence of a signal, 95% confidence level mass limits of M(H(+/-+/-)(L))>118.4 GeV/c(2) and M(H(+/-+/-)(R))>98.2 GeV/c(2) are set for left-handed and right-handed doubly charged Higgs bosons, respectively, assuming 100% branching into muon pairs.

Arterial ischaemic stroke in children

OBJECTIVE

Arterial ischaemic stroke (AIS) in childhood is a serious disorder about which little is published. The aim of this study is to determine the epidemiology and outcome of AIS in Australian children.

METHODS

Cases of childhood AIS occurring at the Royal Children's Hospital, Melbourne 1993-2001, were identified by medical record search using International Classification of Disease Codes. Information was collected on demographics, risk factors, arterial distribution, results of thrombophilic testing, management and outcome.

RESULTS

During the 8 years of review 95 patients presented with 98 cases of AIS calculating an incidence of 1.8 per 100000 children per year. Children less than 12 months of age represented greater than one third of all cases. Identifiable risk factors were present in 64% of cases with congenital heart disease the major risk factor. Thrombophilic testing was incomplete with initial abnormalities present in 18% of cases tested. The estimated stroke-related mortality was 8.4%. Of the patients who survived and who had follow-up details available, 78% had a neurological deficit. Twenty-six patients (26%) received anticoagulation. There was no statistically significant association between treatment with anticoagulation and normal neurological outcome.

CONCLUSION

AIS is over-represented in children under 12 months of age and results in death or residual neurological impairment in the majority of cases. Further prospective studies are needed to identify risk factors for poor outcome. The recently established Australian and New Zealand Stroke and Thrombophilia Registry should provide important information on clinical and laboratory based risk factors and create a basis for international clinical trials to improve the outcome of childhood AIS.

Developmental changes in pedunculopontine nucleus (PPN) neurons

The developmental decrease in rapid-eye-movement (REM) sleep in man occurs between birth and after puberty. We hypothesize that if this decrease in REM sleep does not occur, lifelong increases in REM sleep drive may ensue. Such disorders are characterized by hypervigilance and sensory-gating deficits, such as are present in postpubertal onset disorders like schizophrenia, panic attacks (a form of anxiety disorder), and depression. The decrease in REM sleep in the rat occurs between 10 and 30 days of age. We studied changes in size and physiological properties of pedunculopontine nucleus (PPN) cells involved in the control of arousal, i.e., waking and REM sleep. During the largest decrease in REM sleep (12-21 days), cholinergic PPN neurons doubled in cell area, the hypertrophy peaking at 15-16 days, then decreasing in area by 20-21 days. Noncholinergic PPN cells did not change in area during this period. We confirmed the presence of two populations of PPN neurons based on action potential (AP) duration, with the proportion of short-AP-duration cells increasing and long AP duration decreasing between 12 and 21 days. Most cholinergic and noncholinergic cells had short AP durations. Afterhyperpolarization (AHP) duration became segregated into long and short AHP duration after 15 days. Cells with short AP duration also had short AHP duration. The proportion of PPN cells with Ih current increased gradually, peaking at 15 days, then decreased by 21 days. These changes in morphological and physiological properties are discussed in relation to the developmental decrease in REM sleep.

Cerebral sinus venous thrombosis in children

OBJECTIVE

Cerebral sinus venous thrombosis (cerebral SVT) is rare in children. Information on clinical characteristics, radiological findings and outcome is emerging.

METHODS

Cases of cerebral SVT diagnosed between 1995 and 2001 were identified by a computer-assisted search using International Classification of Disease codes. Medical records were reviewed to collect information on clinical presentation, investigations, treatment and outcome.

RESULTS

Sixteen cases of cerebral SVT were identified. All cases presented in association with head and neck pathology. The majority of cases presented with symptoms of raised intracranial pressure and focal neurological signs. Magnetic resonance imaging identified all cases of cerebral SVT whilst CT scanning failed to demonstrate the diagnosis in two cases. Management with anticoagulation was associated with radiological resolution of the thrombosis and normal neurological outcome. Long-term follow up demonstrated neurological deficits in greater than 40% of patients.

CONCLUSION

Cerebral SVT in children is associated with significant residual neurological morbidity. Prospective studies to identify predictors of outcome and effective management interventions are required.

Survey of the growth characteristics and body composition of Fulani children in a rural hamlet in northern Nigeria

This paper reports the results of a cross-sectional study of the growth of Fulani children, aged 1-16 years, living in the Jos Plateau of northern Nigeria. This particular population of Fulani are semi-nomadic pastoralists whose economy and culture are centered on cattle. We measured the heights and weights of 176 girls and 164 boys and determined their body composition parameters (fat content, fat-free mass, and phase angle) using bioelectrical impedance analysis. The body mass index values for the boys and girls were 14.9 and 15.0 kg/m2, respectively. When the heights and weights of the Fulani children were compared against World Health Organization standards, the incidence of stunting and underweight was high: 46 per cent of the girls and 57 per cent of the boys, respectively, had weight Z-scores below -1.0, and 42 per cent and 57 per cent had height Z-scores below -1.0. Even when weight was adjusted for height, the boys and girls fell well below their age- and gender-matched standards. The percentage fat content of the children declined with age such that by age 16 years the fat content of the boys was 10 per cent and that of the girls 20 per cent. Although the Fulani children were significantly shorter and lighter than the international standards, their phase angle value (determined by bioelectrical impedance analysis), which is a measure of body cell mass and the overall vitality and health of tissue membranes, was comparable to those of similarly aged healthy children in the United States. These results indicate that although a large proportion of the Fulani children who inhabit the Jos Plateau are stunted and underweight, the bioelectrical properties of their tissue membranes suggest that they are relatively healthy. It is not known if the slow growth of the Fulani children has a genetic basis or if it is the result of nutritional shortcomings.

The angiogenic receptor KDR is widely distributed in human tissues and tumours and relocates intracellularly on phosphorylation. An immunohistochemical study

AIMS

Angiogenesis is an important factor in tumour growth and metastasis. Vascular endothelial growth factor receptor 2 (VEGFR-2) or KDR plays a crucial role in angiogenesis. The aim of this study was to raise and characterize antibodies against phosphorylated KDR which could be used for studies on human tissues to assess KDR activation and novel inhibitors of KDR activation in clinical trials.

METHODS AND RESULTS

Three monoclonal antibodies and one rabbit polyclonal antiserum were produced. The specificity of the antibodies was confirmed by ELISA. One of the mouse antibodies and the rabbit polyclonal antiserum reacted with a 200-kDa band on a Western blot of human umbilical vein endothelial cell (HUVEC) lysates, the molecular weight of KDR. Immunohistochemical staining showed that phosphorylated KDR is present in a wide variety of normal tissues including liver, colon and placenta, and is not restricted to endothelium. It was also present in a number of human tumours including breast carcinomas, colonic carcinomas and non-Hodgkin's lymphomas. The pattern of staining was membranous, cytoplasmic and nuclear.

CONCLUSIONS

This study has shown that phosphorylated KDR is present in a wide variety of tumour and tissue types and is not confined to endothelium.

Heparin-induced thrombocytopenia in children

OBJECTIVE

To audit the frequency of heparinoid (standard heparin and low molecular weight heparin) use in a tertiary paediatric hospital, and to determine the occurrence of heparin-induced thrombocytopenia (HIT).

METHODS

A 1-week cross-sectional audit of all heparinoids given to inpatients at a tertiary paediatric hospital was undertaken and a retrospective medical record review of all suspected HIT cases at the tertiary paediatric centre over a 2-year period was carried out.

RESULTS

One hundred and sixteen patients received heparinoid medications over a 7-day period. An average of 29 children received heparin daily. The retrospective medical record review identified four patients with suspected HIT over a 2-year period. Two patients developed thrombotic complications, which were fatal in one patient.

CONCLUSION

Heparin is used frequently in paediatric tertiary hospitals, yet the occurrence of HIT in children is much lower than that reported in adults. Improved laboratory techniques could facilitate improved screening and diagnosis of this serious adverse drug reaction.

Sedation practices for Australian and New Zealand paediatric oncology patients

OBJECTIVES

Paediatric oncology patients often require repeated bone marrow aspirates and lumbar punctures. These procedures commonly require sedation and analgesia. The Australian and New Zealand College of Anaesthetists and the American Academy of Pediatrics have published guidelines that provide recommendations on monitoring and staffing requirements during sedation of paediatric patients. A survey was conducted of the oncology units in Australia and New Zealand in order to compare current practices with published guidelines.

METHODS

Telephone interviews were conducted with nursing or medical staff members.

RESULTS

Fourteen oncology units collectively perform approximately 130 procedures each week, of which 74% are performed under general anaesthesia. Of the remainder, most are performed using conscious sedation. Most units adhere to published recommendations regarding equipment and staffing during procedures performed under sedation. Only a minority of units follow guidelines regarding documentation; fasting requirements; observation and documentation of vital signs during and after the procedure; and obtaining informed consent for procedures performed using sedation.

CONCLUSION

Sedation practices among paediatric oncology units in Australia and New Zealand vary. None of the units fully adhere to published guidelines on childhood sedation. Paediatric oncology units should be familiar with the content of these guidelines and make an informed decision as to their usefulness, both in directing best clinical practice, and in supporting current practice in the event of medico-legal challenge.

Post-thrombotic syndrome

Post-thrombotic syndrome (PTS) is a potentially disabling complication occurring in up to 67% of adult patients following deep venous thrombosis (DVT). PTS has recently been recognised in children. We present three cases of symptomatic PTS in children, which occurred following the use of central venous lines (CVLs). In two cases, no symptoms of acute thrombosis were noted. The cases highlight the clinical presentation of this syndrome. A review of the literature revealed two reports describing PTS occurring in children following DVT with an estimated incidence of 7-12%. It is concluded that PTS is an important complication of DVT in children. The clinical findings of pain, swelling, and brawny induration are similar to adult patients. The effect on growing limbs is not known. Paediatricians should be aware of the potential of PTS in all children who are at risk of DVT, including patients with malignancy, congenital heart disease, and children who have had previous CVLs, even in the absence of documented acute DVT.

A method for measuring particle number emissions from vehicles driving on the road

Earlier research has demonstrated that the conditions of dilution of engine exhaust gases profoundly influence the size distribution and total number of particles emitted. Since real world dilution conditions are variable and therefore difficult to simulate, this research has sought to develop and validate a method for measuring particle number emissions from vehicles driving past on a road. This has been achieved successfully using carbon dioxide as a tracer of exhaust gas dilution. By subsequent adjustment of data to a constant dilution factor, it is possible to compare emissions from different vehicles using different technologies and fuels based upon real world emission data. Whilst further optimisation of the technique, especially in terms of matching the instrument response times is desirable, the measurements offer useful insights into emissions from gasoline and diesel vehicles, and the substantial proportion of particles emitted in the 3-7 nanometre size range.