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Biomedical subjects

T Booth

Publications and source records attributed to T Booth.

At least 19 recordsLinked to original sources
PubMed2005

Automated variance reduction for MCNP using deterministic methods.

In order to reduce the user's time and the computer time needed to solve deep penetration problems, an automated variance reduction capability has been developed for the MCNP Monte Carlo transport code. This new variance reduction capability developed for MCNP5 employs the PARTISN multigroup discrete ordinates code to generate mesh-based weight windows. The technique of using deterministic methods to generate importance maps has been widely used to increase the efficiency of deep penetration Monte Carlo calculations. The application of this method in MCNP uses the existing mesh-based weight window feature to translate the MCNP geometry into geometry suitable for PARTISN. The adjoint flux, which is calculated with PARTISN, is used to generate mesh-based weight windows for MCNP. Additionally, the MCNP source energy spectrum can be biased based on the adjoint energy spectrum at the source location. This method can also use angle-dependent weight windows.

Algorithms↗
PubMed2003

Late onset seizures, hemiparesis and blindness in hemolytic uremic syndrome.

Neurologic complications of hemolytic uremic syndrome, including seizures, usually occur early during the acute phase of the illness. We report a3-year-old girl with classic diarrhea-associated hemolytic uremic syndrome who developed late onset seizures, hemiparesis and transient blindness on the 17th hospital day, at which time her recovery was characterized by improvement in her blood pressure, serum electrolytes, renal function, hematocrit and platelet count. A CT and MR revealed brainstem and posterior parietal and occipital infarct/edema. The association of these radiologic findings within the posterior distribution along with visual loss and seizures are unique to posterior reversible encephalopathy syndrome. Within 7 days, she regained motor function and vision and had no further seizure activity. At 6 months follow-up, physical examination revealed normal motor function and vision and a repeat MR showed near resolution of the previous findings with minimal occipital lobe gliosis. This case report describes the uncommon finding of late onset seizures occurring during the recovery phase of hemolytic uremic syndrome with MR findings consistent with posterior reversible encephalopathy syndrome.

Blindness↗
PubMed2001

Congenital foregut duplication cysts of the anterior tongue.

OBJECTIVE: To review our experience with foregut duplication cysts of the anterior tongue, an unusual and rarely encountered mass in this location. DESIGN: A retrospective review of patients with anterior tongue foregut duplication cysts identified between 1990 and 2000. SETTING: Academic, tertiary care children's medical center. PATIENTS: Six pediatric patients (5 boys and 1 girl) ranging in age from birth to 8 months at diagnosis. INTERVENTION: Three patients underwent preoperative magnetic resonance imaging (MRI). All 6 patients underwent excisional biopsy. MAIN OUTCOME MEASURES: Clinical description of foregut duplication cysts, ability to make the diagnosis preoperatively, and recurrence rates. RESULTS: No patient presented with respiratory compromise, despite the large size of the anterior tongue masses (range, 1.5-2.4 cm). An MRI study was performed in 3 patients, all given a presumptive diagnosis of dermoid cyst based on the radiographic findings. No patient was diagnosed correctly prior to surgical excision. All patients underwent surgical excision, and the average time from birth to surgical excision was 11 months (range, 3 days to 3.7 years). Surgical pathologic findings were reported as a foregut duplication cyst (enterocystoma) in all patients, with 3 specimens containing foci of gastric mucosa. No recurrence has occurred at 1-month follow-up. CONCLUSIONS: Foregut duplication cysts rarely present in the anterior tongue and are easily misdiagnosed preoperatively. An MRI study is helpful in preoperative planning, although all lesions were radiologically indistinguishable from dermoid cysts. These masses may be an underappreciated entity in the differential diagnosis of congenital anterior tongue masses.

Choristoma↗
PubMed2001

Is first trimester exposure to the combination of antiretroviral therapy and folate antagonists a risk factor for congenital abnormalities?

OBJECTIVES: To assess use of antiretroviral therapy (ART) by HIV positive pregnant women in London since 1994 and the risk of congenital abnormalities associated with multidrug exposure during the first trimester of pregnancy. METHODS: Retrospective multicentre study of medical, obstetric, and paediatric notes of all mother-infant pairs, where the mother was known to be HIV infected before delivery, using a standardised proforma. RESULTS: In this study of 195 mother-infant pairs, use of ART during any stage of pregnancy increased from 33.3% in 1994 to 92.5% in 1999 (p=0.01, trend). First trimester exposure increased from 0% in 1994 to 27.5% in 1999 (p=0.00045, trend). Congenital malformations were observed in nine infants (4.6%). Compared with infants not exposed to ART or folate antagonists during the first trimester (n=148), exposure to both ART and folate antagonists during the first trimester (n=13) was associated with an increased risk of congenital abnormalities (4% v 23.1%; OR 7.10, 95% CI 1.5, 34.2). No malformations were observed in the 34 children exposed to either ART or folate antagonists alone during the first trimester. CONCLUSION: An increasing number of HIV infected women conceived while on ART. Although there is no evidence of teratogenicity caused by ART if given alone during the first trimester, exposure to the combination of ART and folate antagonists was associated with a significantly higher risk of congenital abnormalities in this cohort.

Abnormalities, Drug-Induced↗
PubMed2000

The use of gated cine phase contrast and MR venography in achondroplasia.

OBJECTS: Foramen magnum and jugular foramen stenosis, well-known problems in achondroplasia, may result in brain stem compression and venous outflow obstruction, respectively. We studied a series of children with achondroplasia using gated cine phase contrast (PC) CSF flow studies to evaluate CSF dynamics across the foramen magnum and MR venography (MRV) to depict obstructed venous drainage. METHODS: Ten patients (9 months to 11 years, mean 2.85 years) were referred for possible brain stem compression. MRI included routine sequences, cine PC with velocity encoding (VENC) = 5 cm/s, and MRV. Six patients, including the asymptomatic patient, had brain stem compression without tonsillar herniation; two had tonsillar herniation; and two had neither brain stem compression nor tonsillar herniation. Abnormal tonsillar movement was seen only with tonsillar herniation. MRV showed steno-occlusive disease of the internal jugular vein (IJV) in nine patients, sigmoid sinus in four, and absent or hypoplastic transverse sinus in seven. Veno-occlusive disease was not progressive. No patient had massive hydrocephalus, although larger ventricles were associated with more profuse venous collateral formation and more severe degrees of IJV stenosis. Three patients have undergone CSF diversion. CONCLUSIONS: MR imaging may be useful in defining the pathophysiology of brain stem compression and hydrocephalus in achondroplasia.

Achondroplasia↗
PubMed2000

MR venography in children with complex craniosynostosis.

PURPOSE: Chronic venous hypertension due to jugular foramen stenosis has been proposed as an etiology for the hydrocephalus and tonsillar herniation seen in some patients with complex craniosynostosis. We report the use of MR venography (MRV) to evaluate venous outflow obstruction in this clinical setting. MATERIALS AND METHODS: We studied 17 patients, (ages 4 months to 34 years; mean 7.3 years) with complex craniosynostosis; 8 patients with Crouzon's syndrome, 2 with Apert's, 1 with Pfeiffer's and 6 patients without an eponymous classification. MR imaging included routine imaging sequences and axial 2D TOF MRV. Patterns of venous drainage and the presence of hydrocephalus and tonsillar herniation were noted. RESULTS: Jugular vein obstruction was seen in 12/17 patients; in 5/8 patients with Crouzon's, 1/2 with Apert's, the single patient with Pfeiffer's and 5/6 patients with nonsyndromic craniosynostosis. The predominant collateral drainage was via the posterior condylar veins. Nine of 12 (75%) of the patients with abnormal MRV had hydrocephalus; 3/8 patients with Crouzon's, 1/2 patients with Apert's, and 5/6 nonsyndromic patients. Two patients had hydrocephalus with normal MRV. Ten patients had tonsillar herniation, which was associated with shunted hydrocephalus in 7/10 patients, and hydrocephalus seen prior to shunt placement in 3/9. Nine of 10 patients with tonsillar herniation had an abnormal MRV, while 1 patient had a normal MRV. Venous pressures measured in 1 patient showed an 8-mm-Hg differential across the skull base. CONCLUSIONS: The posterior condylar veins appear pivotal in maintaining venous drainage when the jugular bulbs are occluded. Although the association between venous outflow obstruction, hydrocephalus and tonsillar herniation is intriguing, evidence of venous outflow obstruction by MRV may not be indicative of significant intracranial venous hypertension.

Adolescent↗
PubMed2000

Against the odds: growing up with parents who have learning difficulties.

For this article we drew on material from a study in which we explored how people who were brought up in a family headed by a parent or parents with learning difficulties managed the transition to adulthood. Using evidence from in-depth interviews, we provided an assessment of how the now-adult children came through what would generally be seen as a risk-filled upbringing. Despite the problems they encountered in their childhood, many of which originated outside the home, most of the informants had maintained a valued relationship with their family and remained close to their mother.

Adolescent↗
PubMed2000

Idiopathic ischemic cerebral infarction in childhood: depiction of arterial abnormalities by MR angiography and catheter angiography.

BACKGROUND AND PURPOSE: We report our experience with MR imaging, MR angiography, and catheter angiography in children with acute idiopathic cerebral infarction and suggest that catheter angiography may still play an important role in this setting. METHODS: During the past 8 years, 18 children with idiopathic cerebral infarction underwent MR imaging and catheter angiography; 17 were also studied with MR angiography. MR imaging was done within 34 hours after onset of hemiplegia or seizures or both. Sixteen patients underwent catheter angiography within 36 hours of MR imaging; 12 studies were performed within 22 hours. Two patients underwent catheter angiography, in both cases within 72 hours. Infarcts were compared with arterial abnormalities seen at catheter angiography, and the results of MR angiography were compared with those seen at catheter angiography. RESULTS: Comparing MR angiography with catheter angiography, we found the positive predictive value of MR angiography for arteriopathy was 100%, with a negative predictive value of 88%. MR angiography was equivalent to catheter angiography in the detection and depiction of proximal middle cerebral artery disease; however, depiction of disease in the internal carotid artery (ICA) and detection of peripheral embolic disease were better with catheter angiography than MR angiography. CONCLUSION: Basal ganglia lesions associated with ICA disease by MR angiography should probably be studied with digital subtraction angiography, as MR angiography did not depict the length and severity of ICA disease as well as catheter angiography did. Hemispheric infarcts should be studied with catheter angiography, as emboli may occur in the absence of heart disease; the circle of Willis may be uninvolved with embolic disease, and MR angiography is not sensitive to emboli in small peripheral intracranial arteries.

Acute Disease↗
PubMed2000

Velogenic Newcastle disease in imported caged birds.

Velogenic Newcastle disease was diagnosed in pet birds intended for importation into Canada. Virological and histopathological examination confirmed the presence of the disease. The group of birds was denied entry into Canada. Similar birds illegally imported are a potential source of velogenic Newcastle disease virus and are a threat to domestic poultry.

Animals↗
PubMed1997

Specific interactions between human integrin alpha v beta 3 and chimeric hepatitis B virus core particles bearing the receptor-binding epitope of foot-and-mouth disease virus.

Purified integrin alpha v beta 3 was used in solid-phase binding studies with chimeric hepatitis B cores which carry the RGD-containing loop of VP1 protein of the foot-and-mouth disease virus (FMDV). High levels of specific binding between the integrin and the particles were detected by enzyme-linked immunosorbent assays. The binding was Mn2+ cation dependent and could be competed with fibronectin, vitronectin, and the peptide GRGDSPK. Particles in which the RGD motif had been mutated to RGE failed to bind, indicating that the chimeric cores bound specifically to the ligand binding site of integrin alpha v beta 3. Electron micrographs showed several individual alpha v beta 3 molecules bound to the surface of each chimeric particle. Collectively, these data constitute firm evidence that the RGD-containing loop of FMDV is critical for binding to alpha v beta 3 and provide support for identification of alpha v beta 3 as a potential cellular receptor for FMDV.

Antigens, Viral↗
PubMed1994

The use of depth interviewing with vulnerable subjects: lessons from a research study of parents with learning difficulties.

This paper explores the practicalities of using the technique of depth interviewing with people who have learning difficulties. The authors set out to provide other researchers with guidance in the use of the life story approach and to demonstrate its utility with this vulnerable and devalued group of informants. They conclude that depth interviewing can provide new knowledge not accessible through other methods of data collection, and offers a way of giving people with learning difficulties a voice in the making of their own history.

Confidentiality↗
PubMed1994

Mutation of either of two cysteine residues or deletion of the amino or carboxy terminus of nonstructural protein NS1 of bluetongue virus abrogates virus-specified tubule formation in insect cells.

Virus-specific tubules are characteristic of orbivirus infections and are likely to play an important role in virus morphogenesis. It has been shown that for bluetongue virus (BTV), the prototype orbivirus in the family Reoviridae, the virus-encoded NS1 protein forms tubules in insect cells when the BTV segment M6 gene is expressed by using a baculovirus vector. To understand the function of NS1 tubules and to identify the sequences involved in their polymerization, a series of mutant NS1 genes was generated and expressed in insect cell cultures by using baculovirus vectors. Three of the mutants were deletion mutants. One (AcNS1.dNT10) lacked 10 of the amino-terminal amino acids, and the other two mutants (AcNS1.dCT20 and AcNS1.dCT43) lacked 20 or 43 of the carboxy-terminal amino acids. In addition, site-directed mutants were constructed in which various single cysteines or pairs of cysteines were changed to serines. The ability of each mutant protein to form tubules was investigated. None of the deletion mutants formed tubules. The constructs in which the cysteines at amino acid positions 337 and/or 340 were replaced by serines (e.g., AcNS1.C337S,C340S) also did not form tubules. Instead, the NS1 protein of these and the deletion mutants made ribbon-like structures which formed large aggregates. Mutations involving six other cysteines (i.e., AcNS1.C37S,C43S,AcNS1.C462S,C465S, AcNS1.C104S, and AcNS1.C364S) produced tubules. The results show that both the amino and carboxy termini of the NS1 protein molecule and the cysteines at residues 337 and 340 are essential for tubule formation.

Animals↗
PubMed1992

Preparation of platelet concentrates after overnight hold at 20 degrees C.

The clinical demand for platelet concentrates has increased dramatically in the last decade, and poses logistical problems for regional transfusion centres. Pietersz et al. (Vox Sang 1989; 56: 145-150) have shown that it is possible to prepare clinically effective platelet concentrates with substantially reduced white cell contamination, whilst maintaining satisfactory levels of factor VIII:C after holding whole blood at 20 degrees C overnight. This approach offers a method of production that will allow platelet concentrates to be prepared from potentially all donations collected, without resorting to extensive out-of-hours working. Following laboratory evaluation of the procedure we were able to reproduce Pietersz's findings, although hypotonic shock response results were less favourable than observed in our routine platelet concentrates.

Cold Temperature↗
PubMed1991

The social impact of asthma.

While much research has examined the aetiology and treatment of asthma, little work has been done on its social impact. Yet asthma, like any disease, has a social as well as a medical dimension and it is increasingly being recognized that these two dimensions are interlinked. This paper describes a study into the social and personal impact of asthma on the lives of sufferers and their families. It shows that people are affected in many different ways: in employment, schooling, physical activities, social interaction, personal relationships and emotional well-being. All of the people interviewed had experienced some impact on their lives, albeit to varying degrees. The overall social impact was positively correlated with the severity of the asthma itself; this correlation was statistically significant in the case of adults and children under school age.

Absenteeism↗
PubMed1991

Relocation and the characteristics of hospital and hostel regimes.

Drawing on evidence from a research evaluation of a local community care programme, this paper explores whether relocation from a British National Health Service mental handicap hospital into local authority hostels (supervised residential facilities) brought about a qualitative change in the residential environment of movers towards less restrictive management practices and caring routines, more responsive attitudes towards their rights and needs as individuals, and greater control over their own lives. The conclusions point to the existence of a substantial measure of overlap in the fundamental characteristics of the hospital and hostel regimes.

Attitude of Health Personnel↗
PubMed1990

Construction of genetically engineered baculovirus insecticides containing the Bacillus thuringiensis subsp. kurstaki HD-73 delta endotoxin.

The delta-endotoxin gene from Bacillus thuringiensis subsp. kurstaki HD-73 was inserted into Autographa californica nuclear polyhedrosis virus (AcMNPV) using two transfer vector systems. In the first, the delta-endotoxin gene was placed under the control of the polyhedrin gene promoter in lieu of the polyhedrin coding sequences, thus deriving a polyhedrin-negative virus. In the second, it was inserted under the control of a copy of the AcMNPV p10 promoter positioned upstream of the polyhedrin gene to produce a polyhedrin-positive virus. Analysis of infected cell extracts showed that the delta-endotoxin was expressed in insect cells as 130K, 62K and 44K proteins, with peak syntheses at 18 h post-infection. Each of these products reacted with antisera specific for the complete protoxin and the cleaved, active form. When extracts from the cells infected with the polyhedrin-negative virus were fed to Trichoplusia ni larvae, feeding by the insects was inhibited and deaths occurred that were inconsistent with virus infection. This effect was also observed after the inoculum had been treated with detergents to inactivate virus particles prior to feeding to the larvae. These data indicate that the expression of the B. thuringiensis delta-endotoxin gene by a baculovirus in insect cells produces material with insecticidal activity. The biological activities of the two recombinant viruses were assessed in conventional bioassay tests by feeding virus particles or occlusion bodies to the insects. The polyhedrin-negative virus preparation appeared to be contaminated with endotoxin which inhibited feeding of the insects and prevented determination of the LD50 value. The polyhedrin-positive virus had an LD50 value about twofold higher than that of unmodified AcMNPV. The significance of these data for the genetic engineering of virus insecticides is discussed.

Animals↗
PubMed1989

Perspectives of people with learning difficulties on relocation and community care.

Steady progress is being made in the UK in the deinstitutionalisation of services for people with learning difficulties. Growing numbers are moving out of long-stay hospitals and hostels into less restrictive settings. But so far little is know about how they respond to the way these policies are changing their lives. This paper presents the views of movers who were interviewed using an innovative 'visual game' technique as they went through the process of relocation. Based on findings from a longitudinal research evaluation of a local community care programme, the paper describes the methods used and discusses the choices and preferences of the movers. The implications for policymakers are clear. People with learning difficulties can make perfectly sensible, consistent and illuminating comments on their experiences, and favour options and environments that maximise their independence. The evidence from this study suggests that the policy of relocating people from hospitals and developing community alternatives to institutional living is entirely in keeping with the wishes of the users themselves.

Community Health Services↗