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Biomedical subjects

J Blackwell

Publications and source records attributed to J Blackwell.

At least 19 recordsLinked to original sources
PubMed2006

Life expectancy of adult liver allograft recipients in the UK.

BACKGROUND: Liver transplantation is a very successful therapy for those with end stage disease. Although there are numerous data on patient and graft survival after liver transplantation, life expectancy and possible loss of life (compared with a normal matched population) in those who survive remains unknown. AIMS: To assess the life expectancy and life years lost of adult liver allograft recipients, compared with an age and sex matched UK population to provide patients with more information and to improve the use of a scarce resource. METHODS: Using the National Transplant Database held by UK Transplant, on over 3600 adult liver allograft recipients transplanted between 1985 and 2003, we analysed survival of all adults who survived more than six months after transplantation and compared survival after transplantation with national age and sex matched controls to assess life years lost. RESULTS: Estimated median survival time of the analysis cohort of 2702 adult liver allograft recipients was 22.2 years (95% confidence interval 19.3-25.6), with an estimated loss of seven life years compared with an age and sex matched population. CONCLUSIONS: Overall, female recipients have a longer life expectancy and lose fewer life years than male recipients. While younger recipients have a longer life expectancy, they also lose more life years. Those transplanted for cancer, hepatitis C virus infection, and alcoholic liver disease had the greatest loss of life years.

Adolescent↗
PubMed2004

Salivary IgA response to prolonged exercise in a hot environment in trained cyclists.

UNLABELLED: The aim of this study was to determine the effects of prolonged exercise in hot conditions on saliva IgA (s-IgA) responses in trained cyclists. On two occasions, in random order and separated by 1 week, 12 male cyclists cycled for 2 h on a stationary ergometer at 62 (3)% V(.)O(2 max) [194 (4) W; mean (SEM)], on one occasion (HOT: 30.3 degrees C, 76% RH) and on another occasion ( CONTROL: 20.4 degrees C, 60% RH). Water was available ad-libitum. Venous blood samples and 2-min whole unstimulated saliva samples were collected at pre, post and 2 h post-exercise. The s-IgA concentration was determined using a sandwich-type ELISA. Exercising heart rate, rating of perceived exertion, rectal temperature, corrected body mass loss (P<0.01) and plasma cortisol (P<0.05) were greater during HOT. The decrease in plasma volume post-exercise was similar on both trials [HOT: -6.7 (1.1) and CONTROL: -6.6 (1.3)%; P<0.01]. Saliva flow rate decreased post-exercise by 43% returning to pre-exercise levels by 2 h post-exercise (P<0.05) with no difference between trials. Saliva IgA concentration increased post-exercise (P<0.05) with no difference between trials. Saliva IgA secretion rate decreased post-exercise by 34% returning to pre-exercise levels by 2 h post-exercise (P<0.05) with no difference between trials. These data show that a prolonged bout of exercise results in a reduction in s-IgA secretion rate. Additionally, these data demonstrate that performing prolonged exercise in the heat, with ad libitum water intake, does not influence s-IgA responses to prolonged exercise.

Adaptation, Physiological↗
PubMed2001

Nonlinear viscoelasticity of concentrated solutions of aggrecan aggregate.

Aggrecan, the major cartilage proteoglycan, is the macromolecular species primarily involved in the resiliency of cartilage tissue. Most aggrecan molecules occur in cartilage extracellular matrix as aggregates. Each aggregate has a supramolecular structure, with many highly anionic, brushlike aggrecan subunits noncovalently bound to a hyaluronan chain. To better examine the viscoelastic properties of aggrecan aggregate, contaminating subunits were removed by exclusion chromatography. At physiologic ionic strength, concentrated solutions of purified aggrecan aggregate exhibit predominantly elastic behavior at small shear strains. However, above a critical strain, gamma c, the shear moduli show a pronounced strain-softening transition, where the storage modulus decreases suddenly, and the loss modulus exhibits a maximum. At small stresses, the creep function is also highly elastic, exhibiting an equilibrium compliance and large recoverable compliance. When the stress is amplified, a discrete transition to viscous flow occurs at a yield stress sigma y. These nonlinear responses are similar to previous observations for close-packed colloidal suspensions of soft spheres, such as microgel or emulsion particles, for which a yield transition occurs when the stress and deformation are sufficient to move a particle past its neighbors.

Aggrecans↗
PubMed2001

Management of chronic hepatitis C.

One purpose of the Clinical Practice Guideline column is to increase the awareness of the broad availability of existing guidelines and recommendations on various health topics. The hepatitis C virus (HCV) currently accounts for 20% to 40% of acute viral hepatitis, 60% to 80% of chronic hepatitis, and 20% to 30% of cirrhosis, end-stage liver disease, and liver cancer. Nearly four million Americans are currently infected with hepatitis C. Nurse practitioners should be aware of the recommendations regarding the diagnosis, management, and monitoring of the disease. This column summarizes the content of two NIH documents regarding the care of patients with hepatitis C: Management of Hepatitis C: NIH Consensus Statement (NIH, 1997) and Chronic Hepatitis C: Current Disease Management (NIDDK, 2000).

Algorithms↗
PubMed2001

Clinical practice guideline: screening and diagnosing autism.

The clinical practice guideline (CPG) reviewed in this month's column concerns the screening and diagnosis of autism. Autism is the third most common developmental disability and affects more than 1 in 500 children, or nearly 400,000 people in the United States, in some form. Primary care providers of children, including pediatric nurse practitioners (PNPs) and family nurse practitioners (FNPs), should reasonably expect to care for at least one child with autism (CWA). The American Academy of Neurology (AAN) has therefore developed guidelines to help healthcare providers facilitate the early identification of children with autism.

Autistic Disorder↗
PubMed2000

High-temperature ultrafast liquid chromatography.

A novel liquid chromatographic system which enables high temperature ultrafast liquid chromatography (HTU-FLC) has been designed through the careful consideration of heat transfer, band broadening, and pressure drop. Studies of the effect of linear velocity on the HETP show that column efficiency at high velocity, especially of well-retained solutes, dramatically improves at higher temperatures. At 150 degrees C, at a flow rate of 15 mL/min with a 5 cm by 4.6 mm (i.d.) column packed with 3 microns polystyrene-coated zirconia porous particles, long chain alkylphenones were completely resolved, and the analysis time could be decreased by a factor of 50 compared to that at room temperature (25 degrees C) at a conventional flow rate (4 mL/min). In addition, using pure water as the mobile phase, five phenols were separated in less than 30 s.

Chromatography, Liquid↗
PubMed2000

Trunk muscle activation in open stance and square stance tennis forehands.

Electromyography of the trunk muscles were compared between the open and square stance forehand drives of 14 collegiate tennis players. Surface EMG were bilaterally collected from the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) in open and square stance forehand drives. EMG data were transferred by telemetry, 12 bit A/D converted at 1000 Hz, and stored for analysis. Rectified and smoothed EMG data were normalized (NEMG) to maximal isometric voluntary contractions and mean NEMG were calculated during the forward swing and follow through phases of the stroke. A 2 x 2 x 2 x 6 factorial ANOVA (Gender, Stance, Phase, Muscle) with repeated measures on Subject showed significant (p < 0.05) effects of Gender, Muscle, Phase, and several interactions. The nonsignificant differences in muscle activation between stances did not support the belief of tennis experts that open stance forehands require greater trunk activation than square stance forehands. Mean NEMG of the ES were significantly (p < 0.05) larger than EO or RA, which was consistent with observations of tennis-specific strength imbalances and increasing incidence of low back injuries in tennis.

Abdomen↗
PubMed1999

Translational Diffusion Coefficients of Bovine Serum Albumin in Aqueous Solution at High Ionic Strength.

We report static and dynamic light scattering measurements on bovine serum albumin (BSA) solutions at high ionic strength (I) where potential and hydrodynamic interactions between BSA molecules are of comparable strengths. Measurements of the concentration dependence of the osmotic compressibility, (dpi/dc), and the translational diffusion coefficient, D(m), are presented for several solvent systems: (a) at the isoelectric pH = 4.7 and I = 0.1, where long-range electrostatic repulsions are absent; (b) at pH = 7.4 and I = 0.15, 1.5, and 3.3, where a well-screened electrostatic repulsion is present. The results are compared with theoretical predictions which involve a microscopic hard-sphere treatment of the potential and hydrodynamic interactions. At pH = 7.4 and I = 1.5, our experimental results for dpi/dc are in good agreement with the hard-sphere prediction, and our values for D(m) are, likewise, consistent with a hard-sphere hydrodynamic analysis in which contributions from the divergence terms in the velocity field are neglected. At the isoelectric pH, similar agreement with theory is obtained, provided the contribution of an attractive potential is included; at pH 7.4 and I = 0.15, the contribution from a long-range repulsion must be included; at pH 7.4 and I = 3.3, onset of protein aggregation is observed. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Age of transfused blood is an independent risk factor for postinjury multiple organ failure.

BACKGROUND: Blood transfusion has repeatedly been demonstrated to be an independent risk factor for postinjury multiple organ failure (MOF). Previously believed to represent a surrogate for shock, packed red blood cell (PRBC) transfusion has recently been shown to result in neutrophil priming and pulmonary endothelial cell activation. We have previously observed that the generation of inflammatory mediators is related to the length of PRBC unit storage. The purpose of this study was to determine if age of transfused PRBC is a risk factor for the development of postinjury MOF. METHODS: Using our prospective database of trauma patients at risk for developing MOF, we identified patients who developed MOF (MOF+) and received 6 to 20 units of PRBCs in the first 12 hours following injury. A similar cohort of patients, matched for ISS and transfusion requirement, who did not develop MOF (MOF-) were also identified. The age of each unit of PRBC transfused in the first 6 hours was determined. Multiple logistic regression was performed to determine if age of transfused blood is an independent risk factor. RESULTS: Sixty-three patients were identified, 23 of whom were MOF+. There was no difference in ISS and transfusion requirement between MOF+ and MOF- groups. MOF+ patients, however, were significantly older (46+/-4.7 years versus 33+/-2.3 years). Moreover, mean age of transfused blood was greater in the MOF+ patients (30.5+/-1.6 days versus 24+/-0.5 days). Similarly, the mean number of units older than 14 and 21 days old were greater in the MOF+ patients. Multivariate analysis identified mean age of blood, number of units older than 14 days, and number of units older than 21 days as independent risk factors for MOF. CONCLUSION: The age of transfused PRBCs transfused in the first 6 hours is an independent risk factor for postinjury MOF. This suggests that current blood bank processing and storage technique should be reexamined. Moreover, fresh blood may be more appropriate for the initial resuscitation of trauma patients requiring transfusion.

Adult↗
PubMed1998

Adoptive immunotherapy for relapse of chronic myeloid leukemia after allogeneic bone marrow transplant: equal efficacy of lymphocytes from sibling and matched unrelated donors.

Lymphocyte transfusion from the marrow donor (DLT) is well established as an effective therapy for relapse of CML post allogeneic BMT. Reports thus far have been mostly limited to patients who received DLT from a matched sibling donor. We compared the efficacy and toxicity of DLT in 30 patients who were treated with cells from their HLA-identical sibling (n = 18) or from their phenotypically HLA-matched unrelated marrow donor (n = 12). The overall probability of obtaining a cytogenetic remission was 69% (95%CI: 51-83%) and was not significantly different between the two groups. The disease stage at the time of DLT was the only factor associated with cytogenetic remission by multivariate analysis; patients treated in cytogenetic or molecular relapse (n = 11) were seven times more likely (RR = 7.4, 95%CI: 2.4-22.4, P = 0.0005) to respond compared to patients treated for hematologic relapse (n = 19). There was a trend towards more acute GVHD II-IV in the unrelated donor group (58 vs 39%, P = 0.09), but the probability of developing extensive chronic GVHD was not significantly different (56 vs 39%, P = 0.4). We conclude that transfusion of donor cells from HLA-matched volunteer donors does not appreciably increase the risk of GVHD compared with transfusion of cells from HLA-identical siblings in patients with CML who relapse following allogeneic BMT. Conversely, there is no evidence for an increased graft-versus-leukemia effect after DLT from volunteer donors.

Adult↗
PubMed1997

Inhibition of FIV replication by a ribozyme that targets the Rev response element.

The feline immunodeficiency virus (FIV) Rev protein and its cognate sequence the Rev response element (RRE) are essential for virus replication. Thus, the inhibition of either Rev or RRE function can significantly inhibit FIV replication. In the present study, we constructed a ribozyme that targets the RRE sequence and determined its ability to inhibit FIV replication. The RRE ribozyme cleaved the target molecule both in vitro and in FIV-infected cells. Furthermore, FIV replication was reduced significantly in the presence of the RRE ribozyme. FIV provides a good animal model system with which to develop novel antiviral strategies for the human immunodeficiency virus.

Feline Acquired Immunodeficiency Syndrome↗
PubMed1997

Simian foamy virus type 1 (SFV-1) induces apoptosis.

Foamy virus infection causes cytopathology in several cell types from different species. The mechanism of cell killing by foamy viruses is not known. In this report, the mechanism of cell death induced by simian foamy virus type 1 (SFV-1) infection was investigated in fibroblast and lymphoid derived cells lines. Infected L-929 (fibroblast) and Raji (B cell) cells showed chromatin condensation, chromatin cleavage into nucleosome oligomers, and ultrastructural changes consistent with apoptosis. These data suggest that SFV-1 induced apoptotic cell death in different cell lines from different species. The degree of apoptotic cell death in both L-929 and Raji cell lines correlated with increased virus replication. Apoptosis, therefore, is one mechanism by which SFV-1 causes cell death.

Animals↗
PubMed1997

Paranasal sinusitis following allogeneic bone marrow transplant.

In attempt to identify major clinical features of paranasal sinusitis following allogeneic BMT, we reviewed 44 consecutive cases diagnosed at the Hammersmith Hospital between August 1993 and December 1995. All patients had symptoms and signs characteristic of sinusitis. Plain radiographs and/or CT scans revealed fluid levels in 86.4% of patients, opacification in 9.1%, and marked mucosal thickening in 4.5%. Two-thirds of patients were diagnosed within 120 days of BMT. The WBC was less than 1 x 10(9)/1 in 16.3% of patients, the neutrophil count was less than 0.5 x 10(9)/1 in 18.6%, and serum immunoglobulins were depressed (< 6.7 g/l) in 40.6%. Grade III-IV acute GVHD was present in 25.6% of patients and grade I-II in 66.7%; 68.6% developed chronic GVHD. There were 70.5% of patients receiving corticosteroids. Specific pathogens could not be identified in most cases. Pneumonia was present in 10 patients, seven of whom had Aspergillus species identified by bronchoalveolar lavage. Parainfluenza virus was isolated in three patients and Pseudomonas aeruginosa in two. Although all patients received antimicrobial therapy, 70.5% developed chronic sinusitis. Fatal complications did not occur. In 94 consecutive patients receiving allografts for CML during the period of study, WBC and neutrophil counts were lower 3 months post-BMT in patients who developed sinusitis (P < 0.02). Patients receiving higher doses of total body irradiation (13.2 and 14.4 Gy) had a greater probability of developing sinusitis (P = 0.023). Sinusitis occurred in only one of 37 patients receiving autologous transplants in the same period. Sinusitis is common following allogeneic BMT. Leukopenia is often present, but microbiological diagnosis is difficult, and progression to chronic sinusitis common.

Adolescent↗
PubMed1997

Upper extremity angular kinematics of the one-handed backhand drive in tennis players with and without tennis elbow.

Wrist and elbow angular kinematics and racket acceleration at impact were measured in the tennis one-handed back-hand drive for three groups of players: Professionals with no history of tennis elbow (PRO), intermediates with no history of tennis elbow (- TE), and intermediates with a history of tennis elbow (+ TE). Electrogoniometer, strain gauge, and accelerometer signals were sampled for thirty strokes at 1000 Hz. The first ten strokes with central impacts were analyzed. Angular kinematics and racket acceleration at impact were analyzed with planned comparisons ANOVA. A significant (p < 0.05) difference in mean wrist angular velocity after impact was observed between the PRO group (-4.04 rad/s of extension) and the + TE group (0.42 rad/s of flexion). No significant differences were observed in impact acceleration or elbow angular kinematics. Eccentric wrist extensor muscular actions through impact may be important area of study for one-handed backhands and TE.

Acceleration↗
PubMed1996

Rheological studies of the interaction of mucins with alginate and polyacrylate.

The associative interaction of purified ovine and porcine submaxillary mucins (OSM and PSM) with sodium alginate was evaluated by comparing the rheological properties of mixtures against those of pure alginate and mucin in dilute, semi-dilute, and concentrated solutions. These systems were investigated as models for the interaction of mucin with the extracellular alginate produced by Pseudomonas aeruginosa. In dilute solution, evidence for such interaction cannot be obtained because aggregate species exist both in the OSM-alginate mixtures as well as in pure OSM. However, in the semi-dilute regime, mixtures containing a higher proportion of mucin show systematically higher viscosities than those predicted by simple additivity. In concentrated solutions containing higher proportions of mucin, an enhanced elastic response is observed. These results demonstrate a substantial binding interaction of mucins with alginate. This property is not observed in mixtures containing a high proportion of alginate, suggesting that mucins possess relatively low numbers of interacting sites. Introduction of 3 mM Ca2+ ions to all mucin-alginate mixtures enhances the elasticity due to gelation of alginate. Finally, comparison of the rheological properties of PSM-alginate mixtures with those of PSM-polyacrylate mixtures indicates that the binding strength of alginate to mucin is significantly weaker than that of polyacrylate.

Acrylic Resins↗