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J Brown

Publications and source records attributed to J Brown.

At least 91 records · Page 5Linked to original sources
PubMed2002

Clinical bond failure of pre-coated and operator-coated orthodontic brackets.

OBJECTIVES: To test the hypothesis that there is no significant difference in clinical bracket failure between the 3M APC Mini Twin bracket system and the Transbond XT adhesive during orthodontic treatment. DESIGN: A randomized, split mouth, prospective clinical trial. SETTING AND SAMPLE POPULATION: The Department of Orthodontics and Dentofacial Orthopedics at University of Missouri, Kansas City. Twenty-nine subjects who were treatment planned to receive comprehensive orthodontics using 0.018 slot appliances. EXPERIMENTAL VARIABLE: The adhesive pre-coated brackets (APC) system was randomly assigned to one side of the mouth and the Transbond XT was assigned to the opposite side. OUTCOME MEASURE: The absence of any of the brackets at the time of a regular or emergency orthodontic appointment. RESULTS: There was no significant difference (P > 0.05) in bracket failure between the 3M APC Mini Twin bracket system and the Transbond XT adhesive at any time period (90, 180, or 365 days). The failure rate of brackets on premolars was higher than on incisors or canines. CONCLUSION: APC Mini Twin bracket system and Transbond XT adhesive are equally effective in maintaining brackets clinically. Inexperienced operators had an overall 7.5% bond failure 12 months following bracket placement.

Acrylic Resins↗
PubMed2002

Delayed presentation of post-traumatic aneurysm of the posterior inferior cerebellar artery in a patient with spinal cord injury.

STUDY DESIGN: A case report. OBJECTIVE: To present and discuss the case of a patient with serious head and spinal injuries who suffered delayed haemorrhage from a post-traumatic aneurysm of the right posterior inferior cerebellar artery following surgical treatment of vertebral fracture and hydrocephalus. SETTING: National Spinal Injuries Unit and Institute of Neurological Sciences, Southern General Hospital, Glasgow, Scotland, UK. METHODS: Clinical and radiological follow-up of the patient. RESULTS: The aneurysm was treated by coil occlusion of the right vertebral artery. Post-operative films showed that the aneurysm had been successfully obliterated. CONCLUSION: Post-traumatic cerebral aneurysms are very rare. Neurosurgical and rehabilitation teams need to be aware of this late treatable sequela of head injury.

Adolescent↗
PubMed2002

The cost-effectiveness of population Helicobacter pylori screening and treatment: a Markov model using economic data from a randomized controlled trial.

BACKGROUND: Economic models have suggested that population Helicobacter pylori screening and treatment may be a cost-effective method of reducing mortality from gastric cancer. These models are conservative as they do not consider that the programme may reduce health service peptic ulcer and other dyspepsia costs. We have evaluated the economic impact of population H. pylori screening and treatment over 2 years in a randomized controlled trial and have incorporated the results into an economic model exploring the impact of H. pylori eradication on peptic ulcer disease and gastric cancer. METHODS: Subjects between the ages of 40 and 49 years were randomly invited to attend their local primary care centre. H. pylori status was evaluated by (13)C-urea breath test and infected individuals were randomized to receive omeprazole, 20 mg b.d., clarithromycin, 250 mg b.d., and tinidazole, 500 mg b.d., for 7 days or identical placebos. Economic data on health service costs for dyspepsia were obtained from a primary care note review for the 2 years following randomization. These data were incorporated into a Markov model comparing population H. pylori screening and treatment with no intervention. RESULTS: A total of 2329 of 8407 subjects were H. pylori positive: 1161 were randomized to receive eradication therapy and 1163 to receive placebo. The cost difference favoured the intervention group 2 years after randomization, but this did not reach statistical significance (11.42 ponds sterling per subject cost saving; 95% confidence interval, 30.04 ponds sterling to -7.19 pounds sterling; P=0.23). Analysis by gender suggested a statistically significant dyspepsia cost saving in men (27.17 ponds sterling per subject; 95% confidence interval, 50.01 pounds sterling to 4.32 pounds sterling; P=0.02), with no benefit in women (-4.46 per subject; 95% confidence interval, -33.85 pounds sterling to 24.93 pounds sterling). Modelling of these data suggested that population H. pylori screening and treatment for 1,000,000 45-year-olds would save over 6,000,000 pounds sterling and 1300 years of life. The programme would cost 14, 200 pounds sterling per life year saved if the health service dyspepsia cost savings were the lower limit of the 95% confidence intervals and H. pylori eradication had only a 10% efficacy in reducing mortality from distal gastric cancer and peptic ulcer disease. CONCLUSIONS: Modelling suggests that population H. pylori screening and treatment are likely to be cost-effective and could be the first cost-neutral screening programme. This provides a further mandate for clinical trials to evaluate the efficacy of population H. pylori screening and treatment in preventing mortality from gastric cancer and peptic ulcer disease.

Adult↗
PubMed2002

Transforming growth factor-beta1 mediates coexpression of the integrin subunit alphaE and the chymase mouse mast cell protease-1 during the early differentiation of bone marrow-derived mucosal mast cell homologues.

BACKGROUND: Mucosal mast cells (MMC) play a central role in gut hypersensitivities and inflammation. They are morphologically, biochemically and functionally distinct from their connective tissue counterparts. Massive hyperplasia of MMC occurs 7-10 days after intestinal infection with nematodes but it has never been possible to replicate this phenomenon in vitro. OBJECTIVE: (1) To determine whether mouse bone marrow-derived mast cells (mBMMC) grown in the presence of transforming growth factor (TGF)-beta1 could develop over the same time frame (7-10 days) as MMC in parasitized mice. (2) To compare the early expression of surface receptors (integrins alphaE and beta7, c-kit and FcepsilonR) with that of the MMC-specific granule chymase mouse mast cell protease-1 (mMCP-1). METHODS: Mouse bone marrow cells were cultured in the presence of IL-9, IL-3 and Stem Cell Factor (SCF) with or without TGF-beta1. mBMMC were quantified after toluidine blue or Leishmans' staining. Expression of MMC-specific mouse mast cell proteases was analysed by ELISA, immunohistochemistry and RT-PCR. Surface antigen expression was characterized by flow cytometry and confocal microscopy. RESULTS: TGF-beta1 promotes the development of abundant MMC-like mBMMC from bone marrow progenitor cells with kinetics, which closely parallel that seen in vivo. mRNA transcripts encoding mMCP-1 and -2 are readily detectable by day 4 ex vivo in cultures grown in the presence of TGF-beta1. Between 30 and 40% and 75-90% of the cells in these cultures on days 4 and 7, respectively, have typical mast cell morphology, are c-kit+, FcepsilonR+, integrin alphaEbeta7+, and express and secrete abundant mMCP-1. The integrin alphaE subunit is coexpressed with mMCP-1. CONCLUSION: The kinetics of mMCP-1+/alphaE+ mBMMC development, regulated by TGF-beta1, are consistent with that seen in vivo in the parasitized intestine. The normally down-regulatory functions of TGF-beta1 in haematopoiesis are superseded in this culture system by its ability to promote the early expression of alphaE and mMCP-1.

Animals↗
PubMed2002

Impaired system A amino acid transport mimics the catabolic effects of acid in L6 cells.

BACKGROUND: Metabolic acidaemia stimulates protein catabolism in skeletal muscle cells, leading to muscle wasting. As this occurs without decreasing cytosolic pH, the initial signal is unclear. A possible explanation is that extracellular pH acts on solute transporters at the cell surface, inhibiting nutrient influx. DESIGN: Influx through glucose and Pi transporters and System A amino acid transporters into L6 skeletal muscle cells was assessed using 3H-2-deoxyglucose (2-DG), 33Pi and 14C-methylaminoisobutyrate (MeAIB), respectively. Protein degradation (PD) was assessed from 14C efflux from cells prelabelled with 14C-Phe. Branched-chain amino acids and Phe were assayed by selective fluorimetric assays. RESULTS: While acid (pH 7.1) had little immediate effect on 2-DG or 33Pi influx, exposure to pH 7.1 rapidly inhibited MeAIB influx. To determine whether System A inhibition was sufficient to trigger PD, it was blocked at pH 7.5 by a saturating dose (10 mmol L(-1)) of nonmetabolisable substrate (MeAIB). Like acid, this increased PD and decreased total protein. It also mimicked the decreases in protein synthesis, DNA synthesis, glucose transport and glycolysis, and depletion of branched-chain amino acids and Phe, which are induced in L6 by acid. The onset of inhibition of PD by an extracellular Gln load was retarded at pH 7.1, and stimulation of PD by acid was negligible if PD had already been stimulated by Gln depletion. The stimulatory effect of MeAIB on PD was selectively blunted by an excess of Gln, whereas the inhibitory effect of Gln on PD was blocked by excess MeAIB. CONCLUSIONS: The similarity of changes in response to MeAIB and acid implies that these share a common intracellular signalling pathway triggered by inhibition of System A. Even though System A is only a minor contributor to total Gln influx in L6 cells, it is suggested that blockade of System A with acid or MeAIB induces a catabolic state by denying Gln access to a key intracellular regulatory site.

Alanine↗
PubMed2002

Effects of vasoactive intestinal polypeptide on neurones of the rat suprachiasmatic nuclei in vitro.

The suprachiasmatic nuclei (SCN) of the hypothalamus house the main circadian pacemaker in mammals. Vasoactive intestinal polypeptide (VIP) is the most abundant neuropeptide in the SCN and has been shown to phase-shift the electrical activity rhythm of SCN cells in vitro. However, the effects of VIP on the cellular activity of rat SCN neurones are unknown. In this study, we examined the acute effects of VIP on the extracellularly recorded spontaneous firing rate of SCN neurones in an in-vitro hypothalamic slice preparation. Furthermore, with the use of receptor-selective agonists and antagonists, we determined which receptors might mediate the effects of VIP in the SCN. Approximately 50% of cells responded to VIP; the main type of response was suppression in firing rate, although a few cells were activated. Suppression responses to VIP were mimicked by the VPAC(2) receptor agonist Ro 25-1553 and blocked by the selective VPAC(2) receptor antagonist PG 99-465. The PAC(1) receptor agonist maxadilan evoked responses from 40% of SCN cells, and activations to this agonist were not altered by PG 99-465. Responses to VIP were not blocked by antagonists to ionotropic glutamate receptors, but the duration of suppression was modulated by the GABA(A) receptor antagonist bicuculline. Our data indicate that VIP alters the electrical activity of rat SCN neurones in vitro, via both VPAC(2) and PAC(1) receptors.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2002

Major histocompatibility complex susceptibility genes and immune thrombocytopenic purpura in Caucasian adults.

Immune thrombocytopenic purpura (ITP) is a heterogeneous disorder with wide variability in response rates to treatments including corticosteroids, splenectomy and intravenous immune globulins. The nature of the underlying predisposing causes for this autoimmune disorder are not known. We have HLA typed 71 adult Caucasian patients with chronic primary ITP, and compared the data with 750 control samples. In this association study, we were not able to identify a significant immunogenetic susceptibility factor for ITP with HLA class I and class II alleles. However, it appeared that there might be an association between HLA-A2 and ITP, particularly in female patients, who are the predominantly affected group; and HLA-A2 was also present at increased frequency in patients with chronic ITP progressing to splenectomy. These findings are reviewed in the context of other similar reported HLA studies in ITP. Further studies based on larger groups of patients will be necessary to identify genetic susceptibility factors for this disease.

Case-Control Studies↗
PubMed2002

A clinical trial of light cure acrylic resin for orthodontic use.

OBJECTIVE: To ascertain whether or not the less porous surface associated with visible light cure appliances and the absence of free monomer had any measurable affect upon mucosal erythema, and to assess the durability of such appliances in a clinical context. DESIGN: A prospective randomized trial of visible light cure (Triad VLC) and autopolymerizing (Orthoresin) acrylic resin used as orthodontic base plate materials. SETTING: University Dental Hospital and School. SUBJECTS: Fifty subjects from a consecutively enrolled sample of 69 (19 drop outs) for removable appliance therapy (23 VLC, 27 AP). OUTCOME MEASURES: Erythema meter scores and appliance breakages. RESULTS: No statistical difference in mucosal erythema between the two materials was found. Fifty-two per cent of VLC appliances broke during a 6-month period, as opposed to 7 per cent of AP appliances. CONCLUSIONS: VLC appears to have no clinically beneficial effect on the oral mucosa compared with AP. VLC appliances are currently not sufficiently durable to make them a viable alternative to AP appliances.

Acrylic Resins↗
PubMed2002

Uncertainties on predicted concentrations of radionuclides in terrestrial foods and ingestion doses.

Models are routinely used to calculate doses following routine releases and potential accidental releases of radionuclides. These models contain a number of parameters. Values for many of these are not accurately known. The primary aim of this study was to determine the level of uncertainty on predicted concentrations of radionuclides in foods, and doses to individuals consuming those foods, arising from uncertainties on the model input parameter values. A secondary objective was to identify those input parameters whose uncertainty makes a major contribution to the overall uncertainty on the predicted endpoints. The methodology adopted and results obtained are presented for the following radionuclides: 90Sr, 131I, 137Cs and 239Pu. The estimated uncertainty ratios (the ratio of the 95th to the 5th percentile) are frequently very large, often two to three orders of magnitude. The results of this study may be used to identify areas where further research could improve assessment capabilities.

Accidents↗
PubMed2002

Three-dimensional kinematics of the tarsal joint at the trot.

The tarsal joint is a common site of injury for many sport horses. Understanding the biomechanics of this complex joint begins with developing a clear picture of the kinematics during normal locomotion. This study describes the 3D kinematics of the tarsal joint by measuring the motion of the tibia and third metatarsus in 4 sound Quarter Horses with targets attached directly to the bones via steel pins. The objective was to determine if the tarsus had significant motion outside the tarsocrural joint. Two Steinmann pins were inserted into the lateral side of the right hindlimb and marker triads were fixed to the end of each pin. 3D motion of the bones was recorded as each subject trotted in hand. Three rotations were expressed using an attitude vector based on the finite helical angle method. Three translations were calculated as the motion of the tibia relative to the third metatarsus. Angular and translation data were mostly coupled with flexion angle. Internal/external rotation during stance and translations during swing showed evidence of noncoupled motion. Although the majority of tarsal motion occurs in the tarsocrural joint, there is evidence that translations and rotations occur in other locations within the tarsal joint and that some of these are related to the tarsal joint 'snapping' phenomenon. This research provides a set of reference 3D kinematics which will aid in the study of the aetiology and mechanical effects of tarsal joint lameness.

Animals↗
PubMed2002

An investigation into the effect of extending routine mammographic screening to older women in the United Kingdom on the time it takes to screen.

OBJECTIVE: To compare the time it takes to screen women aged 65-69 with women age 50-64. SETTING: Screening centres participating in the Department of Health funded demonstration study of extending breast screening to women aged 65-69. METHODS: Consecutive women of all ages were timed during November 1999 to February 2000, until about 50 women aged 65-69 had been screened at each of the sites. For each woman screened, her age, whether she had been screened before, the times when she checked in, started to get undressed, started screening, finished screening, and when she left the screening unit were recorded. The radiographers also recorded any difficulties associated with screening any of the women in the survey. RESULTS: The total mean time spent at the centres and the time being screened was not significantly different between the two age groups overall or within each of the demonstration sites (p>0.05). The distribution of screen time was similar between the age groups within each of the sites. The proportion of screens reported as difficult by the radiographers differed between sites, with two out of the three sites reporting more problems screening older women. CONCLUSIONS: Despite some radiographers reporting more difficulties associated with screening older women, screening a woman aged 65-69 was found, on average, to take no longer than screening a women aged 50-64 years. Thus, when the NHS breast screening programme is extended to include older women, the same time interval for an appointment can be scheduled regardless of the woman's age.

Aged↗
PubMed2002

An investigation into the number of appointment changes and queries arising as a result of extending breast screening to older women in the United Kingdom.

OBJECTIVE: To compare the number of telephone queries and appointment changes requested by women aged 65-69 with women aged 50-64. SETTING: Department of Health funded demonstration study of extending breast screening to women of 65-69. METHODS: A survey was conducted for 1 week, each month, over the period of a year. Data were collected on the date of the query, the age of the woman, whether and why the appointment was changed, and whether the location for screening was changed. RESULTS: The proportion of telephone queries or appointment changes was significantly more for women aged 50-64 years (p<0.001), 29.7% of women invited aged 50-64 compared with 26.5% of women invited aged 65-69. The main reason for changing the appointments was inconvenience for both age groups. CONCLUSIONS: Administrative costs associated with inviting an older woman for breast screening are no more than those for a woman aged 50-64. The number of telephone calls was high in both age groups, which has resource implications for extending the breast screening programme. The extent of appointment queries or changes needs to be considered in the funding of future population screening programmes with preallocated appointment systems.

Aged↗
PubMed2002

Changes in appetite, food preference, and eating habits in frontotemporal dementia and Alzheimer's disease.

BACKGROUND: Despite numerous reports of changes in satiety, food preference, and eating habits in patients with frontotemporal dementia, there have been few systematic studies. OBJECTIVES: To investigate the frequency of changes in eating behaviours and the sequence of development of eating behaviours in frontotemporal dementia and Alzheimer's disease, using a caregiver questionnaire. METHODS: Three groups of patients were studied: frontal variant frontotemporal dementia (fv-FTD) (n = 23), semantic dementia (n = 25), and Alzheimer's disease (n = 43). Level of education and dementia severity was similar in the three groups. The questionnaire consisted of 36 questions investigating five domains: swallowing problems, appetite change, food preference, eating habits, and other oral behaviours. RESULTS: The frequencies of symptoms in all five domains, except swallowing problems, were higher in fv-FTD than in Alzheimer's disease, and changes in food preference and eating habits were greater in semantic dementia than in Alzheimer's disease. In semantic dementia, the developmental pattern was very clear: a change in food preference developed initially, followed by appetite increase and altered eating habits, other oral behaviours, and finally swallowing problems. In fv-FTD, the first symptom was altered eating habits or appetite increase. In Alzheimer's disease, the pattern was not clear although swallowing problems developed in relatively early stages. CONCLUSIONS: Change in eating behaviour was significantly more common in both of the frontotemporal dementia groups than in Alzheimer's disease. It is likely that the changing in eating behaviours reflects the involvement of a common network in both variants of frontotemporal dementia-namely, the ventral (orbitobasal) frontal lobe, temporal pole, and amygdala.

Aged↗
PubMed2002

Standards and guidelines for performing central dual X-ray densitometry from the Canadian panel of International Society for Clinical Densitometry.

The International Society for Clinical Densitometry (ISCD) is a multidisciplinary nonprofit global organization formed to ensure excellence in densitometry imaging, interpretation, and application. The Canadian panel of the ISCD represents ISCD in Canada and oversees Canadian bone densitometry certification programs. The standards of care from the Canadian panel of the ISCD have been developed in order to establish the minimum level of acceptable performance for the practice of bone densitometry in Canada. A variety of techniques are available for skeletal assessment of bone mineral density, which vary in accuracy, precision, and clinical utility as well as availability. This article focuses on central dual X-ray absorptiometry in adults and does not address densitometry in the pediatric population. Other technologies will be addressed in a subsequent article.

Absorptiometry, Photon↗
PubMed2002

Standards and guidelines for performing central dual X-ray densitometry from the Canadian Panel of International Society for Clinical Densitometry.

The International Society for Clinical Densitometry (ISCD) is a multidisciplinary nonprofit global organization formed to ensure excellence in densitometry imaging, interpretation, and application. The Canadian panel of the ISCD represents ISCD in Canada and oversees Canadian bone densitometry certification programs. The standards of care from the Canadian panel of the ISCD have been developed in order to establish the minimum level of acceptable performance for the practice of bone densitometry in Canada. A variety of techniques are available for skeletal assessment of bone mineral density, which vary in accuracy, precision, and clinical utility as well as availability. This article focuses on central dual X-ray absorptiometry in adults and does not address densitometry in the pediatric population. Other technologies will be addressed in a subsequent article.

Absorptiometry, Photon↗
PubMed2002

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS).

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS) is in progress. The study design, accrual to date, and related research projects are described. Revised accrual rates and expected recruitment are given. 15 cancers have been detected to date, from a total of 1236 screening measurements. This event rate and the tumour grades reported are compared with recent reports from other studies in women at high risk of breast cancer.

Adult↗
PubMed2001

A new strategy for the detection of subtelomeric rearrangements.

We present a new strategy for the detection of subtelomeric rearrangements. This approach is based on two hybridizations with different probe sets. The first set consists of microdissected subtelomeric probes (each 5-10 megabases in size) labeled combinatorially employing 7 different fluorochromes. With this set, subtelomeric interchromosomal exchanges can be detected in a 24-color experiment. The second set comprises a second generation of subtelomeric PAC-, P1- and BAC-clones. Probes for p- and q-arms are labeled with two different colors. This second set detects small deletions; in addition it provides regional information, so that translocated material identified by the first probe set can be assigned to the p- or q-arm of a chromosome. The test has been evaluated in a blind study on a series of subtle translocations and deletions.

Chromosome Painting↗