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Biomedical subjects

D Turner

Publications and source records attributed to D Turner.

At least 19 recordsLinked to original sources
PubMed2001

Sequential magnetic resonance monitoring of pulmonary flow with endovascular stents placed across the pulmonary valve in growing Swine.

BACKGROUND: Patients with endovascular stent implantation for the treatment of right ventricular outflow tract obstruction are often left with incomplete relief of the obstruction and significant pulmonary regurgitation. A noninvasive and reproducible method for monitoring such patients is desirable. MRI in the presence of a stent, however, has to overcome the problem of potential metallic artifacts. METHODS AND RESULTS: Under x-ray fluoroscopic guidance, endovascular nitinol stents were placed across the pulmonary valve in 6 young pigs to induce pulmonary regurgitation. Five additional pigs served as controls. Initial MRI was performed after 2 days (13.5+/-1.8 kg) and follow-up after 3 months (32+/-2.9 kg). Pulmonary flow volumes and regurgitant fraction were quantified by velocity-encoded cine (VEC) MRI through (VEC-TS) and distal to (VEC-DS) the stent. VEC-TS was compared with VEC-DS and volumetric measurements of left and right ventricular stroke volumes provided by cine MRI ("gold standard"). Antegrade and retrograde pulmonary flow volumes by VEC-TS were slightly but significantly less than those with VEC-DS and cine MRI. Excellent correlations (r>0.97) for phasic pulmonary flow volumes as measured by VEC-TS and VEC-DS were shown. Pulmonary regurgitant fraction increased from 32.8+/-15% to 49.6+/-17% (P<0.05) over the course of 3 months with VEC-TS. CONCLUSIONS: MRI demonstrates the progression of pulmonary regurgitation in growing swine. VEC MRI has the ability to quantify pulmonary blood flow inside the lumen of nitinol stents. MRI appears to be ideally suited for monitoring patients with endovascular nitinol stents in the pulmonary artery or pulmonary valve position.

Alloys↗
PubMed2001

The outflow tract of the heart is recruited from a novel heart-forming field.

As classically described, the precardiac mesoderm of the paired heart-forming fields migrate and fuse anteriomedially in the ventral midline to form the first segment of the straight heart tube. This segment ultimately forms the right trabeculated ventricle. Additional segments are added to the caudal end of the first in a sequential fashion from the posteriolateral heart-forming field mesoderm. In this study we report that the final major heart segment, which forms the cardiac outflow tract, does not follow this pattern of embryonic development. The cardiac outlet, consisting of the conus and truncus, does not derive from the paired heart-forming fields, but originates separately from a previously unrecognized source of mesoderm located anterior to the initial primitive heart tube segment. Fate-mapping results show that cells labeled in the mesoderm surrounding the aortic sac and anterior to the primitive right ventricle are incorporated into both the conus and the truncus. Conversely, if cells are labeled in the existing right ventricle no incorporation into the cardiac outlet is observed. Tissue explants microdissected from this anterior mesoderm region are capable of forming beating cardiac muscle in vitro when cocultured with explants of the primitive right ventricle. These findings establish the presence of another heart-forming field. This anterior heart-forming field (AHF) consists of mesoderm surrounding the aortic sac immediately anterior to the existing heart tube. This new concept of the heart outlet's embryonic origin provides a new basis for explaining a variety of gene-expression patterns and cardiac defects described in both transgenic animals and human congenital heart disease.

3T3 Cells↗
PubMed2001

Long-term impact of highly active antiretroviral therapy on HIV-related health care costs.

CONTEXT: Highly active antiretroviral therapy (HAART) is associated with decreased opportunistic infections, hospitalization, and HIV-related health care costs over relatively short periods of time. We have previously demonstrated that decreases in total HIV cost are proportional to penetration of protease inhibitor therapy in our clinic. OBJECTIVE: To determine the effects of HAART on HIV health care use and costs over 44 months. SETTING: A comprehensive HIV service within a Veterans Affairs Medical Center. DESIGN: A cost-effectiveness analysis of HAART. MAIN OUTCOME MEASUREMENTS: The mean monthly number of hospital days, infectious diseases clinic visits, emergency room visits, non-HIV-related outpatient visits, inpatient costs, and antiretroviral treatment costs per patient were determined by dividing these during the period from January 1995 through June 1998 into four intervals. Viral load tests were available from October 1996. Cost-effectiveness of HAART was evaluated by determining the costs of achieving an undetectable viral load over time. RESULTS: Mean monthly hospitalization and associated inpatient costs decreased and remained low 2 years after the introduction of protease inhibitors (37 hospital days per 100 patients). Total cost decreased from $1905 per patient per month during the first quarter to $1090 per patient per month in the third quarter but increased to $1391 per patient per month in the fourth quarter. Antiretroviral treatment costs increased throughout the entire observation period from $79 per patient per month to $518 per patient per month. Hospitalization costs decreased from $1275 per patient per month in the first quarter to less than $500 per patient per month in each of the third and fourth quarters. The percentage of patients with a viral load <500 copies/mL increased from 21% in October 1996 to 47% in June of 1997 (p =.014). The cost of achieving an undetectable viral load decreased from $4438 per patient per month to $2669 per patient per month, but this trend did not reach statistical significance (p =.18). CONCLUSIONS: After an initial decrease, there was an increase in the total monthly cost of caring for HIV patients. Cost increases were primarily due to antiretroviral treatment costs, but these costs were offset by a marked decrease in inpatient-related costs. Increases in costs were not related to antiretroviral treatment failures as measured by the proportion of patients with low or undetectable viral loads. The cost of achieving an undetectable viral load remained stable despite increases in the cost of procuring antiretroviral agents.

Antiretroviral Therapy, Highly Active↗
PubMed2001

A pilot study of the use of mycophenolate mofetil as a component of therapy for multidrug-resistant HIV-1 infection.

Mycophenolic acid (MPA) increases the activity of both abacavir (ABC) and didanosine (ddI) in vitro against wild-type and multinucleoside-resistant HIV. We treated 7 patients with diagnosed AIDS who did not respond to eight or more antiretroviral therapies in an open label pilot study with mycophenolate mofetil (MMF), ABC, ddI, amprenavir (APV), and ritonavir (RTV), with or without efavirenz (EFV). Therapy was well tolerated despite the patients' advanced disease states. No significant decline in lymphocyte or other blood counts was observed. Median HIV RNA was 5.26 log10 copies/ml at entry, 4.53 log10 copies/ml at 4 weeks, and 5.13 log10 copies/ml at 16 weeks. Median CD4+ count was 34 cells/microl at entry and 39 cells/microl at 16 weeks of therapy. CD4+ counts increased further in five study subjects on extended therapy to 25 weeks (median 27 cells/microl at entry, 66 cells/microl at close), despite loss of virologic suppression in 4 of 5 cases. MPA can induce apoptosis in lymphocytes in vitro. However despite viral rebound, cell surface markers of apoptosis and activation declined in total CD3+ cells and CD3+/CD4+ cells twofold to fourfold in 4 of 5 adherent study subjects at 16 weeks, reaching levels comparable with those found in seronegative donors. Although low-dose MMF appears safe in late-stage HIV disease, this study did not demonstrate virologic efficacy. Higher doses of MMF may be more effective. With careful monitoring of toxicities and pharmacokinetics, MMF deserves further testing in HIV therapy.

Adult↗
PubMed2001

Cartoon cover.

Explore the source record for details and available documents.

Cartoons as Topic↗
PubMed2001

A visuomotor reaction time task increases the irregularity and complexity of inspiratory airflow pattern in man.

Previous studies have suggested that motor cortex may be involved in complex control of respiration in man. In this study, we estimated the influence of a simple visuomotor reaction time task (VMT) on the inspiratory airflow curve (IFC) by comparing measurements of standard deviation (SD), C(0) complexity and approximate entropy (ApEn) of the IFC at rest and during VMT conditions. It was found that both C(0) complexity and ApEn, but not SD of the IFC were significantly increased during the VMT challenge. The results suggest that visuomotor pathways may modulate respiratory motor pathways, because an increase in ApEn is suggestive of increased coupling or communication between (motor) systems.

Entropy↗
PubMed2001

HLA-B typing by reference strand mediated conformation analysis using a capillary-based semiautomated genetic analyzer.

The application of reference strand conformation analysis (RSCA) to HLA-A typing using the ABI PRISM 310 capillary based genetic analyzer has recently been described. This study outlines the development and validation of capillary RSCA for HLA-B typing. Mobility values for 93 HLA-B alleles were defined following electrophoresis of known controls through the system. Three fluorescently labelled references, labelled with three different dyes can be electrophoresed simultaneously. The technique was validated by comparing results from 296 cord blood donors with those obtained using reverse SSO. Following capillary RSCA 14.5% of samples required confirmatory typing, compared with a repeat rate of 5.1% following reverse SSO. In samples where no other typing was necessary there was 100% correlation between the two methods. Capillary RSCA for HLA-B typing is quick, easy to implement, and with the introduction of new FLRs and gel matrices has the potential to evolve into a high resolution typing method.

Alleles↗
PubMed2001

Stories seldom told: paediatric nurses' experiences of caring for hospitalized children with special needs and their families.

AIMS OF THE STUDY: This study explored paediatric nurses' experiences of caring for children with special needs and their families in an acute care setting. The aim of the study was to increase understanding of nurses' experiences of caring for these children and their families. The study was designed to reveal the caring practices embedded within these relationships through exploring nurses' stories. STUDY DESIGN/METHODS: Gadamerian hermeneutic phenomenology and feminist research principles were the approaches used to guide the study. Interviews were held with experienced paediatric nurses and interpretation of interview transcripts using a Gadamerian hermeneutic phenomenological approach resulted in the identification of four themes. FINDINGS: The four themes revealed were: Special Relationships; Multiple Dimensions of Who is Expert; Development of Trust Between Nurses and Families; and Feelings of Frustration and Guilt. CONCLUSIONS: The study emphasized the context-specific nature of relationships between nurses and children and their families. The nurses spoke about the difficulties they encountered in their practice and some of the ways that they dealt with these problems. They discussed the things that they valued and those that made them feel guilty and frustrated. In doing so, they revealed their warmth, strength, humanity and caring.

Acute Disease↗
PubMed2001

Pulse rate over pressure evaluation (ROPE) is useful in the assessment of compensated haemorrhagic shock.

OBJECTIVE: To evaluate a calculation of pulse rate over pulse pressure as a method of predicting decompensation in patients with compensated haemorrhagic shock. METHODS: A retrospective cohort study was undertaken enrolling 184 adult victims of major road trauma who were not shocked on presentation to the emergency department. A pulse rate over pressure evaluation was calculated at presentation and vital signs were observed during the first 2 h of emergency department management. RESULTS: Thirty-one patients became shocked during their first 2 h. A ROPE value of greater than 3.0 had a positive predictive value of 53% and a value less than 3.0 had a negative predictive value of 86% for the development of decompensated shock. CONCLUSIONS: ROPE is an easily applied and useful clinical tool with a ROPE of less than 3.0 being predictive of a patient remaining well and a ROPE of above 3.0 being predictive of the patient developing decompensated shock.

Adolescent↗
PubMed2001

District nurse-led beds: an alternative to care at home.

Intermediate care is a key feature of the Government's plans for the development of the health service. The intermediate care scheme described here offers a district nurse-led bed (DNLB) stay in a community hospital to patients in the community who require short-term nursing help. District nurses are given the opportunity to admit patients from their community caseloads into a DNLB in a community hospital and are responsible for their admission, care and discharge. This article describes the pilot study that monitored the first 30 patients who used the DNLBs. Patients included younger people with multiple sclerosis who were admitted for respite care, but the principal beneficiaries were those aged over 65 years with chronic conditions.

Adult↗
PubMed2001

Economics of lower urinary tract symptoms (LUTS) in older people.

Urinary incontinence is an area of clinical and social importance to older people and providers of care. This article provides an update on the 'symptom' of urinary incontinence and reviews the concept of lower urinary tract symptoms (LUTS). The challenges facing health services researchers working in this field are also discussed in terms of trying to quantify the size and extent of the underlying problem. Economic issues and work undertaken to evaluate the cost of LUTS are appraised and the common nonsurgical treatments for LUTS are described together with associated conditions and their cost implications. The cost to individuals and society of LUTS is generally underestimated and the importance of reducing its severity (if cure is not achievable) makes clinical and economic sense.

Aged↗
PubMed2001

[The sensitivity of common bacteria to antibiotics in children in southern Israel].

BACKGROUND: Many reports describe an increasing antibiotic resistance among various pathogenic bacteria. Since every empiric antibiotic treatment is also based on the expected antibiogram of the probable isolate, it is essential to frequently monitor the resistance trends at different ages and contexts. AIM: The purpose of this study was to monitor the antibiogram of a large bacterial population isolated from pediatric bacteremia episodes. METHODS: All bacteremia episodes of children under the age of 18 years in the Soroka Medical Center, Beer Sheva, Israel, were prospectively documented from January 1990 to December 1998. RESULTS: Of the 5,373 positive blood cultures that were noted during the study period, 1,689 were considered as true different episodes. During the years 1990-92, 1993-95 and 1996-98 454, 538 and 697 episodes were noted, respectively. The most common pathogens were Streptococcus pneumoniae (447 isolates), Staphylococcus aureus (224 isolates), Escherichia coli (187 isolates) and Klebsiella spp (180 isolates). The antibiotic sensitivity of the pathogens declined with time in some of the cases and increased in others. The major problems raised were the development of ESBL (extended spectrum beta lactamase) and MRSA (methacillin resistant Staphylococcus aureus) producing isolates, high level of resistance of coagulase negative Staphylococci and Acinetobacter to most of the antibiotic agents, and increasing resistance of Streptococcus pneumoniae to various agents. CONCLUSION: Despite the significant increase in the antibiotic resistance of many of the pathogens tested, there are still various therapeutic options available.

Bacteremia↗
PubMed2000

Changes in electromyogram during upper limb muscle contraction induced by resistive loaded breathing in humans.

Expiratory only resistive loaded breathing (RL) reduces high energy electromyogram (EMG) power (EH) during an isometric contraction of a leg extensor muscle, but not an arm flexor. An interaction between afferent activity during expiratory RL and inspiratory non-loaded phases of breathing, which the contraction spanned, could have accounted for the reduced EH in these long contractions. Therefore this study tested the hypothesis that brief arm extensor muscle contractions (70% of maximal force), performed during a single phase of expiratory RL, would also exhibit reduced EH. Surprisingly, EH in triceps, but not biceps brachii was reduced significantly when the contraction was performed during inspiratory RL rather than expiratory RL. The results suggest that either (a) short and prolonged contractions or (b) motor drive to arm and leg extensors are affected differently by RL.

Adult↗
PubMed2000

Allele frequencies of polymorphisms of the tumour necrosis factor-alpha, interleukin-10, interferon-gamma and interleukin-2 genes in a North European Caucasoid group from the UK.

Cytokine gene polymorphisms affecting cytokine production may influence rejection and graft-versus-host disease following solid organ and haemopoietic stem cell (HSC) transplantation, respectively. Polymorphisms in the regulatory regions of several cytokine genes have been described; for example, tumour necrosis factor-alpha (TNF-alpha) has a G/A substitution at position -308, interleukin-2 (IL-2) has a T/G substitution at position -330 and interleukin-10 (IL-10) has substitutions at positions -1082(G/A), -819(C/T) and -592(C/A). Microsatellites associated with cytokine production have been detected in the first intron of the IFN-gamma gene and flanking the TNF-alpha gene. In this study, we have genotyped a single panel of healthy Northern European Caucasoids living in the south-east of England for the above-mentioned polymorphisms and compared the results to those published for other populations. A PCR method using sequence-specific primers (SSP) was developed for genotyping the IL-2 polymorphism, and the ABI PRISMtrade mark 310 genetic analyser was used to detect the TNF-alpha and IFN-gamma microsatellites. The allele frequencies of all the studied polymorphisms were consistent with those reported for other UK Caucasoid populations, but differences were observed when compared to other Oriental, African and Caucasoid groups. If these cytokine polymorphisms prove to have functional consequences, then any differences across population groups may have significant clinical relevance in disease and in the outcome of solid organ and HSC transplantation.

Alleles↗
PubMed2000

Structure and coding content of CST (BART) family RNAs of Epstein-Barr virus.

CST (BART BARF0) family viral RNAs are expressed in several types of Epstein-Barr virus (EBV) infection, including EBV-associated cancers. Many different spliced forms of these RNAs have been described; here we have clarified the structures of some of the more abundant splicing patterns. We report the first cDNAs representing a full-length CST mRNA from a clone library and further characterize the transcription start. The relative abundance of splicing patterns and genomic analysis of the open reading frames (ORFs) suggest that, in addition to the much studied BARF0 ORF, there may be important products made from some of the upstream ORFs in the CST RNAs. Potential biological functions are identified for two of these. The product of the RPMS1 ORF is shown to be a nuclear protein that can bind to the CBF1 component of Notch signal transduction. RPMS1 can inhibit the transcription activation induced through CBF1 by NotchIC or EBNA-2. The protein product of another CST ORF, A73, is shown to be a cytoplasmic protein which can interact with the cell RACK1 protein. Since RACK1 modulates signaling from protein kinase C and Src tyrosine kinases, the results suggest a possible role for CST products in growth control, perhaps consistent with the abundant transcription of CST RNAs in cancers such as nasopharyngeal carcinoma.

Amino Acid Sequence↗
PubMed2000

Surgical correction of lumbar kyphotic deformity: posterior reduction "eggshell" osteotomy.

OBJECT: Progressive kyphotic deformity of the lumbar or thoracolumbar spine may lead to back pain, cosmetic deformity, and risk of neurological compromise. The authors describe a series of patients in whom they performed a single-stage, posterior reduction ("eggshell") osteotomy procedure to improve sagittal contour by creating lordosis within a single vertebral body. METHODS: From 1995 to 1997 the authors performed 12 osteotomy procedures in 11 patients with thoracolumbar or lumbar kyphosis. Seven patients presented with iatrogenic deformity, three with deformity secondary to traumatic injury, and one patient with ankylosing spondylitis. Their mean age at time of surgery was 46.6 years (range 23-78 years). All patients suffered from back pain and were unable to stand upright, but in only one patient were neurological findings demonstrated. The mean preoperative deformity was -26 degrees (range -90 to 0 degrees). At 6-month follow-up examination the mean sagittal contour measured 17.5 degrees (range - 17 to 44 degrees), indicating that the mean surgical correction was 40.1 degrees (range 25 to 58 degrees). All patients reported decreased back pain at follow up, and none required narcotic analgesic medication. Complications included a dense paresis that developed immediately postoperatively in a patient who was found to have residual dural compression, which was corrected by emergency decompressive surgery. One elderly patient suffered a perioperative cerebrovascular accident, and three patients suffered neurapraxia with transient muscle weakness of the quadriceps. There was one case of a dural tear. There were no deaths, and prolonged intensive care stays were not required. CONCLUSIONS: Single-level posterior reduction osteotomy provides excellent sagittal correction of kyphotic deformity in the lumbar region, with a risk of cauda equina and root and plexus compromise due to the extensive neural exposure.

Adult↗