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Biomedical subjects

J Stanton

Publications and source records attributed to J Stanton.

At least 19 recordsLinked to original sources
PubMed2001

A truly hybrid interventional MR/X-ray system: feasibility demonstration.

A system enabling both x-ray fluoroscopy and MRI in a single exam, without requiring patient repositioning, would be a powerful tool for image-guided interventions. We studied the technical issues related to acquisition of x-ray images inside an open MRI system (GE Signa SP). The system includes a flat-panel x-ray detector (GE Medical Systems) placed under the patient bed, a fixed-anode x-ray tube overhead with the anode-cathode axis aligned with the main magnetic field and a high-frequency x-ray generator (Lunar Corp.). New challenges investigated related to: 1) deflection and defocusing of the electron beam of the x-ray tube; 2) proper functioning of the flat panel; 3) effects on B0 field homogeneity; and 4) additional RF noise in the MR images. We have acquired high-quality x-ray and MR images without repositioning the object using our hybrid system, which demonstrates the feasibility of this new configuration. Further work is required to ensure that the highest possible image quality is achieved with both MR and x-ray modalities.

Brain↗
PubMed2001

Murder misdiagnosed as SIDS: a perpetrator's perspective.

AIMS: Child murder misdiagnosed as sudden infant death syndrome (SIDS) is a difficult area to study. We present a perpetrator's descriptions to enrich clinicians' knowledge of possible presenting features of this phenomenon. METHODS: Interview material was collected as part of a qualitative study of maternal filicide performed from a naturalistic paradigm in order to access the perpetrators' view of events. The woman participant has been convicted for three child murders and two attempted murders which were initially misdiagnosed as SIDS. Interviews were done in the participant's home with her partner present, while she was on leave from prison. Semi-structured interviews were conducted, recorded, transcribed, and analysed for themes. Specific ethical permission was gained to present this case in isolation and the paper was written in consultation with the woman described. RESULTS: She described initial intense attachment to her first victim and described killing her because she was unable to bear her apnoea attacks and her fear of losing her. She described difficulty grieving for this child and subsequent failure to attach to her next child or feel for the other victims. CONCLUSIONS: Expressions of intense attachment to an infant and description of intense grief over a death in a way which engages compassion should not deter a paediatrician from considering the possibility of the parent having killed the child.

Adult↗
PubMed2001

A nurse's aid to clinical selection of pressure-reducing equipment.

The selection of appropriate pressure-relieving equipment for individuals in the community is an important process in the prevention of pressure ulcers. The clinical decision is made by community nurses who are accountable for their actions and who therefore have to have clear rationale for the decisions they make. Risk tools are not a completely reliable or valid method of assessing patients. The current national guidelines (National Institute for Clinical Excellence (NICE), 2001) are not specific in relation to the selection or choice of equipment. This article explores how these decisions are made.

Beds↗
PubMed2000

A qualitative study of filicide by mentally ill mothers.

OBJECTIVE: To examine descriptions of maternal filicide committed in the context of major mental illness from the frame of reference of a group of perpetrators. METHOD: Participants were accessed via their treating psychiatrists. A naturalistic paradigm was used. Semi-structured individual interviews were audio-taped and transcribed. Theme analysis of the transcripts was done by repeated reading of transcripts and coding utterances, individually, then jointly by the authors. RESULTS: Six women were identified, and interviewed. They described intense investment in mothering their child(ren). Descriptions of external stressors were not extreme, but the experience of illness was described as extremely stressful. They described little or no warning or planning. Their descriptions of their children were unremarkable. Motivation was described as altruistic or as an extension of suicide. They described regretting the killings and feeling responsible even though they knew they had been ill at the time. CONCLUSIONS: The findings underline the difficulty of identification of risk and prevention of maternally ill filicide in the women who described being very caring towards their children, and little or no warning of filicidal urges. They may be better understood in terms of the illness than individual stress or psychodynamics.

Adult↗
PubMed2000

Double-blind randomized controlled trial of glutamine-enriched polymeric diet in the treatment of active Crohn's disease.

BACKGROUND: Glutamine is traditionally considered a nonessential amino acid but may be conditionally essential in patients with catabolic conditions. Glutamine-supplemented foods in these patients have been shown to prevent deterioration of gut permeability, protect against the development of intestinal mucosal atrophy, and improve nitrogen balance. Animal models of inflammatory bowel disease suggest that glutamine-enriched enteral diets may lead to less severe intestinal damage, less weight loss, improved nitrogen balance, and reduced disease activity. The purpose of the current study was to compare the efficacy of a glutamine-enriched polymeric diet with a standard low-glutamine polymeric diet in the treatment of active Crohn's disease. METHODS: Eighteen children with active Crohn's disease were randomly assigned to receive a 4-week course of either a standard polymeric diet with a low glutamine content (4% of amino acid composition; group S) or a glutamine-enriched polymeric diet (42% of amino acid composition; Group G). The two diets were isocaloric and isonitrogenous with an identical essential amino acid profile. Remission rates were analysed on an intent-to-treat basis. Changes in clinical and laboratory parameters of disease activity were also compared after 4 weeks of nutritional treatment. RESULTS: Two of the children, both in group G, were withdrawn from the trial because of nontolerance of the diet. There was no difference between the two groups in proportion of patients achieving remission (intent-to-treat basis): 5 (55.5%) of 9 in group S versus 4 (44.4%) of 9 in group G (p = 0.5). Improvement in mean paediatric Crohn's disease activity index (PCDAI) was significantly more in group S (p = 0.002) but changes in orosomucoid level, platelet count, and weight were not different between the groups. CONCLUSIONS: The findings suggest that a glutamine-enriched polymeric diet offers no advantage over a standard low-glutamine polymeric diet in the treatment of active Crohn's disease. Rather, it appears to be less effective in improving PCDAI. The reported beneficial effects of glutamine seen in many catabolic states must be viewed with caution when extrapolating to the management of Crohn's disease.

Acute-Phase Proteins↗
PubMed2000

Kinematics of the wrist. Evidence for two types of movement.

We enrolled 34 normal volunteers to test the hypothesis that there were two types of movement of the wrist. On lateral radiographs two distinct patterns of movement emerged. Some volunteers showed extensive rotation of the lunate with a mean range of dorsiflexion of 65 degrees, while others had a mean range of 50 degrees. The extensive rotators were associated with a greater excursion of the centre of articulation of the wrist. It is suggested that dynamic external fixation of a fracture of the distal radius carries with it the risk of stretching the ligaments or causing volar displacement at the site of the fracture.

Adult↗
PubMed1999

The cost of living: kidney dialysis, rationing and health economics in Britain, 1965-1996.

How important is research in shaping policy when a new life-saving medical technology becomes available, but happens to be very expensive? Taking the case of kidney dialysis, this paper argues that the emerging discipline of health economics had little influence relative to national differences in health service organization and cultures of expectation of provision. Paradoxically, the most effective covert rationing was achieved under the British NHS which ostensibly provides free care for all, while the uncentralised market system in the US gave way, on this issue, to almost universal state-subsidised provision. Under the British system, the most cost-effective options for renal care tended to flourish, but some patients were turned away. Physicians have been held responsible for complying with covert rationing: this paper suggests that early gearing towards socially-useful survival filtered back to selection at primary level, possibly continuing long after specialists wished to expand. Public outcry, though muted, reached parliament and caused minor shifts in policy; the main aim of the voluntary pressure campaign, to release more organs for transplant through 'opt-out', remained unrealised in the UK. Yet dialysis was targetted for expansion in the 1980s just at the point when health economists were presenting evidence for its low cost-effectiveness compared with other expensive interventions. According to the main strand of argument in this paper, comparisons with other countries and between regions were most influential in breaking the hold of covert rationing: policy making by embarrassment. However, in the 1990s, there are both theoretical discussions of explicit rationing, and open intiatives afoot to target dialysis for rationing.

Health Care Rationing↗
PubMed1999

Reticulate evolution and the origins of ribosomal internal transcribed spacer diversity in apomictic Meloidogyne.

Among root knot nematodes of the genus Meloidogyne, the polyploid obligate mitotic parthenogens M. arenaria, M. javanica, and M. incognita are widespread and common agricultural pests. Although these named forms are distinguishable by closely related mitochondrial DNA (mtDNA) haplotypes, detailed sequence analyses of internal transcribed spacers (ITSs) of nuclear ribosomal genes reveal extremely high diversity, even within individual nematodes. This ITS diversity is broadly structured into two very different groups that are 12%-18% divergent: one with low diversity (< 1.0%) and one with high diversity (6%-7%). In both of these groups, identical sequences can be found within individual nematodes of different mtDNA haplotypes (i.e., among species). Analysis of genetic variance indicates that more than 90% of ITS diversity can be found within an individual nematode, with small but statistically significant (5%-10%; P < 0.05) variance distributed among mtDNA lineages. The evolutionarily distinct parthenogen M. hapla shows a similar pattern of ITS diversity, with two divergent groups of ITSs within each individual. In contrast, two diploid amphimictic species have only one lineage of ITSs with low diversity (< 0.2%). The presence of divergent lineages of rDNA in the apomictic taxa is unlikely to be due to differences among pseudogenes. Instead, we suggest that the diversity of ITSs in M. arenaria, M. javanica, and M. incognita is due to hybrid origins from closely related females (as inferred from mtDNA) and combinations of more diverse paternal lineages.

Animals↗
PubMed1998

Shepherd Center.

Explore the source record for details and available documents.

Academies and Institutes↗
PubMed1997

APOE is linked to Alzheimer's disease in a large pedigree.

Although previous association studies have demonstrated that the APOE4 allele is a risk factor for Alzheimer's disease (AD), its value for the prediction of AD in individuals is <100%. The limited predictive value of epsilon4 is also seen in multiply affected families where the epsilon4 allele is not tightly linked to AD. We analyzed a large pedigree multiply affected with AD by lod score linkage analysis at the known loci associated with AD. In this pedigree, the APOE/APOCI gene area was linked to the development of AD, while no linkage was detected to any of the other loci known to be associated with the disease. In this family, then, the inheritance of an epsilon4 allele is highly associated with the early development of the disease (mean age of onset, 62 years), and is a good predictor of disease. However, given the wealth of evidence for association, but not linkage, of APOE4 to AD, we believe this finding suggests that another factor (or factors) interact(s) with APOE to precipitate early disease, and produce positive linkage results. The nature of this factor presently remains unknown.

Age of Onset↗
PubMed1997

No association between the intronic presenilin-1 polymorphism and Alzheimer's disease in clinic and population-based samples.

Mutations in the Presenilin 1 (PS1) gene on chromosome 14 cause most early-onset familial Alzheimer's disease (AD). An intronic polymorphism in the PS1 gene was recently identified and reported to be associated with late-onset AD [Wragg et al., Lancet 347: 509-512, 1996]. The authors found an excess of homozygotes for the more common allele (allele 1) in AD cases, associated with an approximate doubling of risk. In the present study, we report the PS1 polymorphism distributions in clinic and population-based samples. We were not able to replicate the findings of Wragg et al. [1996]. Our results are consistent with those of other researchers and do not support the conclusion that the PS1 polymorphism is associated with late-onset AD.

Alleles↗
PubMed1997

Evolution of the AT-rich mitochondrial DNA of the root knot nematode, Meloidogyne hapla.

Mitochondrial DNA of the root knot nematode Meloidogyne hapla was investigated for intraspecific diversity and divergence from other parthenogenetic root knot nematodes. A 1,900-bp fragment containing COII, tRNAHis, 16S rRNA, ND3 and Cyt b genes has been cloned and sequenced from one individual and an 1,188-bp region within this region was sequenced from four other Australian isolates. M. hapla mtDNA is more than 80% AT-rich, like other Meloidogyne spp. Nucleotide diversity within M. hapla is some 10-fold higher than across three other parthenogenetic species of root-knot nematode (M. arenaria, M. javanica, and M. incognita), implying an earlier origin for M. hapla. Nucleotide divergence between M. hapla and its congener M. javanica is as great as that between Ascaris suum and Caenorhabditis elegans, members of different nematode subclasses, while amino acid sequence difference between Meloidogyne is more than twice as great. This is interpreted as an AT-bias-induced acceleration of the amino acid substitution rate, over and above saturation of nucleotide divergence in the strongly AT-biased DNA, on three lines of evidence: (1) in conserved blocks in 16S rDNA congeneric Meloidogyne have no more differences than between A. suum and C. elegans; (2) the Meloidogyne lineage has more amino acid changes relative to the Ascaris/Caenorhabditis lineage with respect to four of five outgroups, the exceptional outgroup being the only species (Apis) as AT-rich as Meloidogyne; and (3) between the two Meloidogyne there are more first and second but fewer third codon position changes than between the other nematode species. M. hapla is also found to contain a 102-bp tandem repeat of at least 40 copies; a size, arrangement, and position the same as in M. javanica, but sequence comparisons did not demonstrate homology between the two repeats.

Amino Acid Sequence↗
PubMed1997

The direction of the Whitacre needle aperture affects the extent and duration of isobaric spinal anesthesia.

The use of Whitacre spinal needles results in directional flow out of the needle aperture, diverting local anesthetic from the longitudinal axis of the needle. Thus, a change in orientation of the needle aperture would be expected to result in a different local anesthetic distribution in the subarachnoid space. We studied 40 outpatients undergoing elective knee arthroscopy under spinal anesthesia with 60 mg plain lidocaine 2% in a prospective, double-blinded manner. Patients were randomly assigned to either Group I (needle aperture oriented in a cephalad direction throughout intrathecal injection) or Group II (aperture directed caudally). Onset and offset of sensory and motor block were analyzed at frequent intervals. Times to completion of ambulatory milestones, including discharge, were recorded. Group I was characterized by a higher sensory level (T 3.4 +/- 1.3 vs T 6.6 +/- 2.8, P < 0.001). Group I had significantly shorter duration of lumbar sensory anesthesia (149.2 +/- 30.6 min vs 177.8 +/- 23.5 min, P < 0.01) and motor blockade (117.6 +/- 26.1 min vs 150.0 +/- 22.8 min, P < 0.001). Mean time to outpatient discharge was approximately 32 min shorter in Group I. The orientation of the Whitacre needle aperture exerts a major influence on sensory level, as well as the duration of isobaric lidocaine spinal anesthesia.

Adolescent↗