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Biomedical subjects

J Hall

Publications and source records attributed to J Hall.

At least 109 records · Page 6Linked to original sources
PubMed2000

Evaluation of endothelium-dependent vasodilation in the human peripheral circulation.

Flow-mediated vasodilation (FMD) in the brachial artery measured by ultrasound, and the increase in forearm blood flow (FBF) induced by local infusion of a muscarinic-receptor agonist have both frequently been used to evaluate endothelium-dependent vasodilation (EDV) in the human forearm. The present study intended to evaluate the relationship between these techniques and to investigate if vasodilation induced by the muscarinic receptor-agonist methacholine (MCh) was owing to production of nitric oxide (NO). FMD during hyperaemia was assessed by ultrasound and FBF was measured by venous occlusion plethysmography during local infusion of MCh or L-arginine in the human forearm. Both these methods were applied in 26 individuals. In another 12 individuals forearm arterial and venous plasma concentrations of nitrate/nitrite (NOx) were measured together with FBF before and during local MCh infusion. While the change in brachial artery diameter induced by sublingually given nitroglycerine and the vasodilatory response to sodium nitroprusside (SNP) given locally in the forearm were significantly correlated (r = 0.70, P < 0.01), FMD showed no relationship with the vasodilation evoked by MCh (r = -0.03) or L-arginine (r = 0.04). The five-fold increase in FBF during MCh infusion was associated with a significant increase in venous plasma NOx concentrations (P < 0.05) and a more than 11-fold increase in forearm NOx-release (P < 0.01). Thus, a significant relationship between the two methods regarding the evaluation of endothelium-independent vasodilation evoked by NO-donors was found, but no relationship was found between the two methods regarding the evaluation of endothelium-dependent vasodilation. Furthermore, vasodilation induced by MCh in the forearm seems to be induced by NO-release.

Adult↗
PubMed2000

Early stage breast cancer: costs and quality of life one year after treatment by mastectomy or conservative surgery and radiation therapy.

This paper reports a descriptive study of the costs and quality of life (QoL) outcome of treatments for early stage breast cancer in a cohort of Australian women, one year after initial surgical treatment. Mastectomy without breast reconstruction is compared to breast conserving surgery and radiotherapy (breast conservation). Of the 397 women eligible for the study, costing data were collected for 81% and quality of life data for 73%. The cost differences between treatment groups were mainly accounted for by adjuvant therapies, the more expensive being radiotherapy. When compared to women treated by mastectomy, those treated by breast conservation reported better body image but worse physical function. The negative impact of breast cancer and its treatment was greater for younger women, across a number of dimensions of quality of life (regardless of treatment type). While this study shows that breast conservation is more expensive than mastectomy, the QoL results reinforce the importance of patient participation in treatment decisions.

Journal Article↗
PubMed2000

mu-conotoxin GIIIA interactions with the voltage-gated Na(+) channel predict a clockwise arrangement of the domains.

Voltage-gated Na(+) channels underlie the electrical activity of most excitable cells, and these channels are the targets of many antiarrhythmic, anticonvulsant, and local anesthetic drugs. The channel pore is formed by a single polypeptide chain, containing four different, but homologous domains that are thought to arrange themselves circumferentially to form the ion permeation pathway. Although several structural models have been proposed, there has been no agreement concerning whether the four domains are arranged in a clockwise or a counterclockwise pattern around the pore, which is a fundamental question about the tertiary structure of the channel. We have probed the local architecture of the rat adult skeletal muscle Na(+) channel (mu1) outer vestibule and selectivity filter using mu-conotoxin GIIIA (mu-CTX), a neurotoxin of known structure that binds in this region. Interactions between the pore-forming loops from three different domains and four toxin residues were distinguished by mutant cycle analysis. Three of these residues, Gln-14, Hydroxyproline-17 (Hyp-17), and Lys-16 are arranged approximately at right angles to each other in a plane above the critical Arg-13 that binds directly in the ion permeation pathway. Interaction points were identified between Hyp-17 and channel residue Met-1240 of domain III and between Lys-16 and Glu-403 of domain I and Asp-1532 of domain IV. These interactions were estimated to contribute -1.0+/-0.1, -0.9+/-0.3, and -1.4+/-0.1 kcal/mol of coupling energy to the native toxin-channel complex, respectively. mu-CTX residues Gln-14 and Arg-1, both on the same side of the toxin molecule, interacted with Thr-759 of domain II. Three analytical approaches to the pattern of interactions predict that the channel domains most probably are arranged in a clockwise configuration around the pore as viewed from the extracellular surface.

Amino Acids↗
PubMed2000

Use of a hinged external fixator for elbow instability after severe distal humeral fracture.

The authors report the case of a forty-year-old man who developed acute elbow instability after fixation of an open, comminuted distal humeral fracture. Treatment with a hinged, external elbow fixator was successful in reestablishing elbow stability and a functional range of elbow motion. To the best of the authors' knowledge, the use of this device for acute elbow instability after distal humeral fracture fixation has not been previously reported.

Acute Disease↗
PubMed2000

Antibody reactivity against human and guinea pig tissue transglutaminase in children with celiac disease.

BACKGROUND: Highly discriminatory markers for celiac disease are needed to identify children with early mucosal lesions. The purposes of this study were to evaluate the clinical potential of circulating anti-tissue transglutaminase (tTG) immunoglobulin (Ig)A antibodies in the diagnosis of childhood celiac disease and to investigate the extent of autoreactivity of these antibodies. METHODS: Included in this retrospective study were samples from 22 children with biopsy-verified celiac disease, 23 control subjects with disease, and 22 healthy control subjects without any known gastrointestinal or inflammatory disorders. An enzyme-linked immunosorbent assay (ELISA) was used to measure the serum levels of IgA antibodies specific for human and guinea pig tTGs. All samples were also analyzed for antibodies to gliadin and endomysium (EMA). RESULTS: The concentrations of IgA specific for human and guinea pig tTGs correlated with the small intestinal villous structure and the serum levels of IgA EMA. The tTG ELISAs exhibited a high specificity and sensitivity for detection of untreated celiac disease. The human erythrocyte IgA tTG ELISA had the highest sensitivity (100%) and a specificity of 98%. The IgA EMA method had a sensitivity of 95% and the highest specificity (100%) of all tests. CONCLUSIONS: Our results provide additional support to the concept that anti-tTG IgA antibodies can be used as a highly discriminatory serologic marker for celiac disease and that measurements of these autoreactive antibodies may in the future be used as an alternative to the EMA test.

Adolescent↗
PubMed2000

Genomic organization of the UGT2b gene cluster on human chromosome 4q13.

The UDP-glucuronosyltransferases (UGTs) comprise a large family of proteins capable of detoxifying a wide variety of both endogenous and exogenous substrates. The primary function of this gene superfamily is to catalyze the glycosylation of substrates such as biogenic amines, steroids, bile acids, phenolic compounds and various other pharmacologically relevant compounds, including numerous carcinogens, toxic environmental pollutants and prescription drugs. This conjugation increases the solubility of these compounds, allowing them to be excreted more readily through hepatic or renal mechanisms. This paper describes the genomic characterization and chromosomal localization of three UGT2B genes which together comprise part of a large cluster of related sequences, including pseudogenes found on human chromosome 4q13. A genomic map spanning approximately 500-1000 kb of this region reveals the presence of three previously described UGT2B genes, at least two previously uncharacterized pseudogenes and a significant number of remnant gene fragments and places UGT2B4 between UGT2B7 and UGT2B15. Additionally, access to a large reference DNA bank allowed us to calculate allele frequencies for two UGT2B SNPs: D85R in UGT2B15 and Q458D in UGT2B4 amongst 803 unrelated individuals representing five ethnic populations. The data presented here suggest a recent evolutionary history of gene duplication, mutation and rearrangement. Furthermore, they suggest that a re-evaluation of the current description of the UGT2B gene family with respect to the number of specific genes, degree of allelic diversity and molecular evolution may be necessary.

Biological Evolution↗
PubMed2000

Characterization of two highly polymorphic human tryptase loci and comparison with a newly discovered monkey tryptase ortholog.

Tryptases are serine proteases involved in mast cell-mediated inflammatory responses which represent potential targets of drugs against diseases such as asthma, arthritis and inflammatory bowel disease. In order to interpret pharmacodynamic data on the tryptase inhibitors undergoing clinical trials, we defined the genetic variability of the tryptase 1 (TPS1) and tryptase 2 (TPS2) loci by screening a reference population of 32 individuals representing three major ethnic groups (Caucasian, African American, Asian). Using overlapping PCR products, we resequenced the entire tryptase genes with the only exclusion of TPS2 intron 1 and 20 bp of TPS2 5' untranslated region included in exon 1 and we identified 21 novel single nucleotide polymorphisms in TPS1 and 17 single nucleotide polymorphisms plus a large polymorphic deletion in the TPS2 gene. We also compared the type, frequency and distribution of single nucleotide polymorphisms in TPS1 and TPS2 and we observed that the polymorphism frequency within these two loci is unexpectedly high (approximately 1 SNP every 90 bp) and that some of the allele frequencies differ significantly among the three ethnic groups. Based on differences observed in preclinical studies using a cynomolgus monkey (Macaca fascicularis) asthma model system, we investigated the difference between monkey and human tryptase genes in order to better understand the mechanism of action of our tryptase inhibitors.

Amino Acid Sequence↗
PubMed2000

Cost effectiveness analysis of school based Mantoux screening for TB infection.

OBJECTIVE: To assess the cost-effectiveness of adding school based Mantoux screening programs to the New South Wales current TB prevention strategy. METHOD: A decision analysis model compared the costs and consequences of screening strategies against the current no-screen strategy. Costs associated with screening and with treating future cases of TB were considered. Consequences considered were deaths and adult cases of TB prevented. The study was based on data from prevalence surveys conducted in 1992 and 1994 in Central and South Western Sydney, New South Wales. Screening strategies considered were screening all or only overseas born (OSB) 6 year olds and all or only OSB 14 year olds in school settings. RESULTS: Screening 14 year olds prevented more deaths and adult cases of TB than screening 6 year olds for a similar cost. For both age groups targeted screening of OSB children was more cost-effective than screening all children. Targeted screening of 14 year olds--the most cost effective option--cost $17,956 (costs and benefits discounted at 5%) per adult case prevented, equivalent to approximately $130,000 per life year saved. The cost-effectiveness ratios decline substantially if lower discount rates and less conservative assumptions are applied. CONCLUSION: Targeted screening was more cost effective than screening all children, however, there are ethical implications of targeting a group based on their origin of birth. IMPLICATIONS: As prevention and control of TB continues to be a high priority for NSW, the implications of a school based screening program should be seriously considered.

Adolescent↗
PubMed2000

Practical management of hyperinsulinism in infancy.

Hyperinsulinism in infancy is one of the most difficult problems to manage in contemporary paediatric endocrinology. Although the diagnosis can usually be achieved without difficulty, it presents the paediatrician with formidable day to day management problems. Despite recent advances in understanding the pathophysiology of hyperinsulinism, the neurological outcome remains poor, and there is often a choice of unsatisfactory treatments, with life long sequelae for the child and his or her family. This paper presents a state of the art overview on management derived from a consensus workshop held by the European network for research into hyperinsulinism (ENRHI). The consensus is presented as an educational aid for paediatricians and children's nurses. It offers a practical guide to management based on the most up to date knowledge. It presents a proposed management cascade and focuses on the clinical recognition of the disease, the immediate steps that should be taken to stabilise the infant during diagnostic investigations, and the principles of definitive treatment.

Genetic Therapy↗
PubMed2000

Hippocampal volume in adolescent-onset alcohol use disorders.

OBJECTIVE: Alcohol use disorders (defined as DSM-IV alcohol dependence or abuse) are prevalent and serious problems among adolescents. As adolescence is marked by progressive hippocampal development, this brain region may be particularly susceptible to the adverse effects of adolescent alcohol use disorders. This study compared the hippocampal volumes of adolescents and young adults with adolescent-onset alcohol use disorders to those of healthy matched comparison subjects. METHOD: Magnetic resonance imaging was used to measure the hippocampal volumes and volumes of comparison brain regions in 12 subjects with alcohol use disorders and 24 comparison subjects matched on age, sex, and handedness. RESULTS: Both left and right hippocampal volumes were significantly smaller in subjects with alcohol use disorders than in comparison subjects. Total hippocampal volume correlated positively with the age at onset and negatively with the duration of the alcohol use disorder. Intracranial, cerebral, and cortical gray and white matter volumes and measures of the mid-sagittal area of the corpus callosum did not differ between groups. CONCLUSIONS: In the mature brain, chronic alcohol use disorders are associated with graded global brain dysmorphology. Although the etiology, neuropsychological consequences, and permanence of these hippocampal findings need to be further examined, these findings suggest that, during adolescence, the hippocampus may be particularly susceptible to the adverse effects of alcohol.

Adolescent↗
PubMed2000

N-Acetylaspartate concentration in the anterior cingulate of maltreated children and adolescents with PTSD.

OBJECTIVE: Anterior cingulate dysfunction has been implicated in the pathophysiology of posttraumatic stress disorder (PTSD). The authors hypothesized that integrity of the anterior cingulate may be affected in childhood PTSD. METHOD: Single voxel proton magnetic resonance spectroscopy (proton MRS) was used to measure the relative concentration of N-acetylaspartate and creatine, a marker of neural integrity, in the anterior cingulate of 11 children and adolescents who met DSM-IV criteria for PTSD secondary to maltreatment and 11 healthy matched comparison subjects. RESULTS: The ratio of N-acetylaspartate to creatine was significantly lower in the maltreated subjects with PTSD than in the comparison subjects. CONCLUSIONS: The lower N-acetylaspartate/creatine ratio in subjects with PTSD suggests that anterior cingulate neuronal metabolism may be altered in childhood PTSD.

Adolescent↗
PubMed2000

Dizygotic twinning is not linked to variation at the alpha-inhibin locus on human chromosome 2.

Natural multiple pregnancy in women leading to dizygotic (DZ) twins is familial and varies across racial groups, suggesting a genetic predisposition. Mothers of DZ twins have a higher incidence of spontaneous multiple ovulation and elevated FSH concentrations. FSH release is controlled by feedback of inhibin peptides from the ovary, and immunization against inhibin alpha-subunit results in an increased ovulation rate in animals. The inhibin alpha-subunit is therefore a candidate gene for mutations that may increase the frequency of DZ twinning. Restriction digests of a PCR product from exon 1 with the enzyme SpeI detects a C/T polymorphism at bp 128 with two alleles of 447 and 323/124 bp. The polymorphism was typed in 1,125 individuals from 326 pedigrees with 717 mothers of spontaneous DZ twins. The alpha-inhibin locus mapped within 3 centimorgans of D2S164, and linkage with DZ twinning was excluded [decimal log odds ratio (LOD) score, -2.81 at theta = 0]. There was complete exclusion of linkage (LOD, less than -2) of a gene conferring relative risk 1.8 (lambdas, >1.8) across the chromosome, except at the p-terminus region and a small peak (maximum LOD score, 0.6) in the region of D2S151-D2S326. Analysis using either recessive or dominant models excluded linkage with DZ twinning in this population (LOD score, less than -2.5) across chromosome 2. We conclude that dizygotic twinning is not linked to variation in the alpha-inhibin locus. The results also suggest that mutations in other candidates on chromosome 2, including the receptor for FSH and the betaB-inhibin subunit (INHBB) cannot be major contributors to risk for DZ twinning.

Chromosome Mapping↗
PubMed2000

Home or hospital? An evaluation of the costs, preferences, and outcomes of domiciliary chemotherapy.

This study compares the costs and outcomes of domiciliary and hospital-based chemotherapy, using a prospective randomized cross-over design. Eighty-seven eligible patients were recruited from oncology services at two metropolitan hospitals in Sydney, Australia. Forty patients completed study evaluation requirements, having two months of chemotherapy in each location (home and hospital). The domiciliary service was staffed by hospital-based oncology nurses. Marginal costs of domiciliary treatment over hospital treatment were estimated from the health service perspective. Home-based care was more expensive, largely due to extra nurse time. About half of the eligible patients (n = 87) and 73 percent of the evaluated patients (n = 40) preferred domiciliary care. Most evaluated patients and their informal carers were satisfied with the medical care provided, regardless of location. Patient needs were well met in either location, and no differences were found in quality of life. At current throughput rates, providing chemotherapy in the home was more expensive than providing it in hospital. However, if the demand for chemotherapy were to exceed ward capacity by up to 50 percent, moving chemotherapy into the home could provide a less costly strategy for the expansion of a chemotherapy service without compromising patient outcomes.

Cross-Over Studies↗