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Biomedical subjects

E Powell

Publications and source records attributed to E Powell.

At least 19 recordsLinked to original sources
PubMed2006

Radial head fracture in the medial collateral ligament deficient elbow; biomechanical comparison of fixation, replacement and excision in human cadavers.

A widely used clinical recommendation is that in the presence of medial collateral ligament injuries, two-part radial head fractures should be fixed rather than excising or replacing the radial head. Direct biomechanical data comparing fracture fixation, radial head replacement and excision in a human cadaveric elbow model, have not been previously described. Such comparison is clinically important as with the increasing availability of radial head implants and promising follow up results, the role of radial head replacement in fracture management may have to be redefined. In this study, five fresh cadaveric elbows had radial head fracture creation and medial collateral ligament division, fracture fixation, radial head replacement and excision. Valgus and varus laxity were determined using an electromagnetic tracking system. Radial head replacement leads to a similar valgus (P=0.80) [corrected] laxity as compared to radial head fixation. Radial head excision resulted in a significantly greater valgus laxity as compared to radial head fixation (P=0.02) or replacement (P=0.03). Both radial head excision and replacement led to a greater varus laxity as compared to fixation. Our results suggest that in the elbow with medial collateral ligament injury and two-part radial head fracture, fixation is overall biomechanically superior as compared to replacement and excision.

Aged↗
PubMed2004

Bone mineral density in Australian children, adolescents and adults with cystic fibrosis: a controlled cross sectional study.

BACKGROUND: Low bone mineral density (BMD) is recognised in individuals with cystic fibrosis (CF) although the pathogenesis remains unclear. The aims of this study were to compare BMD over a broad continuum of Australian individuals with CF with healthy controls and to examine the relationship between BMD and clinical parameters including physical activity, nutrition, and vitamin D levels. METHODS: BMD of the lumbar spine (LS), total body (TB), femoral neck (FN), cortical wrist (R33%), and distal wrist (RUD) was examined in 153 individuals with CF aged 5.3-55.8 years (84 males) and in 149 local controls aged 5.6-48.3 years (66 males) using dual energy x ray absorptiometry. Anthropometric variables, body cell mass, markers of disease severity, corticosteroid usage, measures of physical activity, dietary calcium and caloric intake and serum vitamin D were assessed and related to BMD. RESULTS: Compared with controls, mean BMD was not significantly different in children aged 5-10 years with CF. Adolescents (females 11-18 years, males 11-20 years) had reduced TB and R33% BMD when adjusted for age, sex, and height (difference in BMD (g/cm2) adjusted means between control and CF: TB=0.04 (95% CI 0.01 to 0.07); R33%=0.03 (95% CI 0.01 to 0.06)). BMD was reduced at all sites except R33% in adults (difference in BMD (g/cm2) adjusted means between control and CF: TB=0.05 (95% CI 0.02 to 0.09); LS=0.08 (95% CI 0.03 to 0.14); FN=0.09 (95% CI 0.03 to 0.15); RUD=0.03 (95% CI 0.01 to 0.05)). In children/adolescents BMD was weakly associated with nutritional status and disease severity. CONCLUSIONS: BMD was normal in a well nourished group of prepubertal children with CF. A BMD deficit appears to evolve during adolescence and becomes more marked in adults. Individuals with CF should optimise nutrition, partake in physical activity, and maximise lung health in order to optimise BMD. Further longitudinal studies are required to understand the evolution of reduced BMD in young people and adults with CF.

Adolescent↗
PubMed2002

Natural and anthropogenic processes that concentrate Mn in rural and urban environments of the lower Mississippi River delta.

This study evaluated natural processes and projected methylcyclopentadienyl manganese tricarbonyl fuel additives as sources of Mn accumulation in the environment. Data sets include fresh alluvium and sediments from the lower Mississippi River Delta and a soil metal survey of metropolitan New Orleans. The (1) railroad Mn, (2) industrial Mn, and (3) dynamic aquifer-stream transfer of Mn hypotheses were tested with the Mississippi River Delta data. Friction between Mn-rich steel wheels and rails contributes Mn (P = 0.017) to the environment, supporting (1). Sediment loads of Mn were similar (P = 0.77) upstream and downstream from the Louisiana industrial corridor, not supporting (2). The median Mn on the alluvium surface (59 mg/kg), in the aquifer (159 mg/kg), and in the riverbank aquifer discharge zone (513 mg/kg) support (3) as a mechanism for Mn enrichment of clay. The New Orleans soil metal survey data set shows a rural to urban increase of fourfold for Mn and three orders of magnitude for Pb. At 1999 U.S. highway fuel use, 8.3 mg of Mn per L would yield 5000 metric tons of Mn annually. If 13% of Mn were emitted, 650 tons of Mn would become aerosols annually, while 87% or 4350 tons would remain in engines. The 1999 toxic release inventory for Mn shows 370 tons as total emissions compared to the potential of 390 and 260 tons from vehicles, respectively, in urban and rural areas. A precautionary lesson from the use of Pb as a fuel additive is that the use of Mn as a fuel additive would be associated with an increased risk for neonates exceeding the estimated total tolerable daily intake of 2.1-16.5 micrograms Mn (especially in urban inner city environments) because neonates lack fully functional hepatic clearance for Mn.

Fresh Water↗
PubMed2001

Frequency and distribution in three ethnic populations of single nucleotide polymorphisms in the MICA gene.

The Homo sapiens major histocompatibility complex (MHC) class 1 chain related gene A (MICA) was scanned for novel single nucleotide polymorphisms (SNPs) using a panel of DNA samples from African-, Japanese- and Mexican-Americans. Overlapping primer-pairs were used to amplify products in the size range of 300 to 400 bp that were sequenced and scanned for SNPs using Phred, Phrap, Polyphred and Consed sequence analysis programs. A total of 16 SNPs were detected, six of which represent new variant nucleotides in the Homo sapiens MICA gene. Three of the variants also represent amino acid changes in the MICA protein. Differences among the three ethnic panels in the frequency of the variant nucleotides observed were inconsistent, but significant for seven of the SNPs detected. Though a small sample size, this study represents the first multi-population based analysis of the frequency and distribution of SNPs in the MICA gene, a locus that may be essential in the antigenic recognition by gammadelta T cells.

Alleles↗
PubMed2001

Marked tachypnea in siblings with chronic beryllium disease due to copper-beryllium alloy.

Two biological sisters working at the same factory for > 9 years developed chronic beryllium disease (CBD) from a copper-beryllium alloy. Both had marked tachypnea (36 breaths/min and 45 breaths/min at rest, respectively), persisting over 8 years. Ventilation during exercise (assessed in one sibling) was grossly excessive (57 L/min, expected 23 L/min) with a respiratory rate of 64 breaths/min even with normal baseline routine pulmonary function tests. Blood beryllium lymphocyte transformation test and lung biopsies confirmed the diagnosis. No other cases of CBD have been reported from this plant among about 120 workers. These cases support the genetic basis for berylliosis and illustrate the marked tachypnea that may accompany this disease.

Alloys↗
PubMed2000

Development and characterization of expressed sequence tags for the turkey (Meleagris gallopavo) genome and comparative sequence analysis with other birds.

Twenty-one randomly selected clones from a turkey (Meleagris gallopavo) pituitary complementary DNA (cDNA) library were sequenced to develop expressed sequence tags (ESTs) for this economically important avian species whose genome is among the least understood. Primers specific for the ESTs were used to produce amplicons from the genomic DNA of turkey, chicken (Gallus gallus), guinea fowl (Numidia meleagris), pigeon (Columba domestica), and quail (Corturnix japonica). The amplicons were sequenced and analyzed for sequence variation within- and similarity among-species and with GenBank database sequences. The proportion of shared bases between the turkey sequence and the consensus sequence from each of the other species ranged from 72% to 93% between turkey and pigeon and quail and between turkey and chicken, respectively. The total number of single nucleotide polymorphisms (SNPs) observed ranged from 3 in quail to 18 in chicken out of 4898 and 5265 bases analyzed, respectively. The most frequent nucleotide variation observed was a C-->T transition. Linkage analysis of one such SNP in the backcross progeny of the East Lansing reference DNA panel, localized TUS0005, the chicken sequence derived from primers specific for turkey TUT2E EST, to chromosome 4. The ESTs reported, as well as the SNPs may provide a useful resource for ongoing efforts to develop high utility genome maps for the turkey and chicken. The primers described can also be used as a tool in future investigations directed at further understanding the biology of the guinea fowl, pigeon and quail and their relatedness to the turkey.

Animals↗
PubMed2000

Locomotor analysis of the taiep rat.

Locomotor activity (tremor, ataxia, immobility, epilepsy, and paralysis) in the taiep rat, which suffers from a myelin deficient disorder, has not been previously documented. This study used walking track analysis of footprints to analyze locomotor activity in the taiep rat in comparison to normal, age-matched controls. The results confirmed differences between normal and taiep rats in terms of stride length, step length, and stride width. In addition, we found significant interactions between age and condition for stride and step length. The results suggest that locomotor analysis is a sensitive indicator of myelin deficiency. The results are discussed in terms of the underlying myelin deficiency and possible treatment regimens.

Animals↗
PubMed1999

The splay angle: A new measure for assessing neuromuscular dysfunction in rats.

This report describes a new method, the splay angle measures, to determine neuromuscular dysfunction. Splay angles are measured from a standard splay test and define hind limb orientation quantified, in degrees, by the paw strike of the hind limbs. We used mutant rats, presenting with a chronic central nervous system demyelinating disease, characterized by tremor, ataxia, immobility, epilepsy, and paralysis (taiep). Significant differences between taiep (n = 12) and normal control rats (n = 10) were found for Linear Splay, AngleLeft, AngleRight, and AngleBoth. These results suggest that the splay angles are a sensitive measure of hind limb orientation and may reflect an underlying pathology.

Animals↗
PubMed1998

Technology and care in a bone marrow transplant unit: creating and assuaging vulnerability.

The article describes the experience of technologically induced vulnerability and the inherent uncertainty of patients undergoing bone marrow transplantation. Examples of care by nurses, as perceived by patients and their family members, are offered. The relationship between the iatrogenic vulnerability and suffering of patients and the nursing response of care is explored. The claim is made that a caring response by nurses enables patients to make meaning of their choice to undergo simultaneously life-saving and life-threatening bone marrow transplantation.

Adaptation, Psychological↗
PubMed1997

Long-term engraftment failure after marrow ablation and autologous hematopoietic reconstitution: differences between peripheral blood stem cell and bone marrow recipients.

We infused peripheral blood stem cells (PBSC) into 51 patients with various malignant disorders, after myeloablative conditioning. Twenty-four patients also received autologous bone marrow (PBSC + BM). In a multivariate analysis, the only statistically significant predictors of neutrophil engraftment were log-dose CFU-GM (P < 0.001) and the number of prior chemotherapy regimens (P = 0.004). The factors predicting RBC and platelet engraftment were log-dose CFU-GM (P = 0.002), PBSC + BM infusion (P = 0.007) and the absence of neoplastic bone marrow involvement (P = 0.009). Seven patients remained platelet and/or red cell transfusion-dependent for 100 days or more post-transplant after good neutrophil recovery. Six of these seven long-term engraftment failures, as well as five additional patients, received < 10(5) CFU-GM/kg. Of the 11 patients who received < 10(5) CFU-GM/kg (low-dose patients), seven were PBSC recipients, of whom six were long-term engraftment failures. In contrast, there were no long-term engraftment failures among the four low-dose autologous marrow recipients. This difference in long-term engraftment failure rate was significant (P = 0.015). The low-dose PBSC patients all had a diagnosis of lymphoma with bone marrow involvement. The low-dose PBSC + BM group was more heterogeneous, but no patient had malignant involvement of the marrow. The low-dose PBSC patients had also received significantly more prior chemotherapy regimens than the low-dose PBSC + BM patients and a significantly higher proportion received total body irradiation (TBI) as part of their conditioning regimen. We conclude that marrow damage resulting from a combination of neoplastic infiltration, chemotherapy and TBI may result not only in low PBSC yields but also in an impaired capacity of the marrow microenvironment to support transplanted stem cells.

Adult↗
PubMed1996

Detection of circulating donor deoxyribonucleic acid by microsatellite analysis in a liver transplant recipient.

The diagnosis of graft-versus-host disease following liver transplantation may be delayed because the clinical and pathological features are nonspecific. We report the use of microsatellites to support a diagnosis of GVHD in a patient who developed fever and a skin rash 28 days after liver transplantation. The pattern of microsatellite alleles amplified from the peripheral blood on day 51 posttransplant indicated that recipient and donor DNA were present in approximately equal proportions. Microsatellite typing is a simple and rapid method to identify high levels of circulating donor DNA to support a diagnosis of GVHD following liver transplantation.

Alleles↗
PubMed1996

Steady-state plasma concentrations of midazolam in critically ill infants and children.

OBJECTIVE: To determine the steady-state plasma concentrations of midazolam in critically ill infants and children. DESIGN: Prospective uncontrolled study conducted over 18 months. SETTING: Regional pediatric intensive care unit in a children's hospital. PATIENTS: Thirty-eight infants and children, aged 1 month to 13 years, requiring midazolam as sedation during mechanical ventilation. The patients were divided into three age groups: (1) infants less than 12 months (n = 16); (2) children 1-2 years (n = 12); and (3) children aged 3 years and older (n = 10). MAIN OUTCOME MEASURES: A single blood sample was collected once steady-state plasma concentrations of midazolam were achieved during a continuous intravenous infusion. Plasma clearance was calculated from the plasma concentrations and infusion rate. RESULTS: The plasma clearance was higher in children aged 3 years and older (median plasma clearance 13.0 mL/min/kg) than in infants and children 1-2 years old (median plasma clearance 3.1 and 2.3 mL/min/kg, respectively) (Kruskal-Wallis analysis of variance, p < 0.01). The midazolam infusion rates were similar for the three groups studied (Kruskal-Wallis analysis of variance, p > 0.05). The plasma concentrations of midazolam were significantly lower in children 3 years and older (median plasma concentration 128 ng/mL) than in infants and children 1-2 years old (median plasma concentrations 395 and 790 ng/mL, respectively) (Kruskal-Wallis analysis of variance, p < 0.05). CONCLUSIONS: The plasma clearance in children 3 years and older was higher than in infants and children up to 2 years old. There was considerable interindividual variation in the steady-state plasma concentrations of midazolam in critically ill infants and children.

Adolescent↗
PubMed1994

Detection of Aeromonas salmonicida, causal agent of furunculosis in salmonid fish, from the tank effluent of hatchery-reared Atlantic salmon smolts.

The fish pathogen, Aeromonas salmonicida, could be detected only by bacteriological culture from the kidney of dead or moribund fish in one tank in a hatchery rearing Atlantic salmon (Salmo salar L.) smolts. However, by using a DNA probe specific for this species, allied to a PCR assay, the pathogen could be detected in water, feces and effluent samples taken from this fish tank. Also, the presence of the pathogen was found in effluent samples from two fish tanks containing apparently healthy fish. Subsequently, the presence of pathogen in these tanks was confirmed by an increase in the daily mortality rate and by a plate culture from moribund fish.

Aeromonas↗