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Biomedical subjects

S Armstrong

Publications and source records attributed to S Armstrong.

At least 19 recordsLinked to original sources
PubMed2007

Wireless connectivity for health and sports monitoring: a review.

This is a review of health and sports monitoring research that uses or could benefit from wireless connectivity. New, enabling wireless connectivity standards are evaluated for their suitability, and an assessment of current exploitation of these technologies is summarised. An example of the application is given, highlighting the capabilities of a network of wireless sensors. Issues of timing and power consumption in a battery-powered system are addressed to highlight the benefits networking can provide, and a suggestion of how monitoring different biometric signals might allow one to gain additional information about an athlete or patient is made.

Computer Communication Networks↗
PubMed2005

A randomised controlled trial of nurse-managed trial conclusion following early phase cancer trial participation.

The effect of a nurse-managed intervention, for early phase cancer trial participants at trial conclusion, on psychosocial outcomes was evaluated at two cancer centres in the Midlands, England using a randomised controlled trial. It involved 117 patients who were participating in an early phase cancer clinical trial. It was a nurse-managed trial exit, which included a trial exit interview, trial feedback information leaflet and telephone follow-up compared with standard care at trial conclusion. Psychological distress at 1 week and 4-6 weeks post-trial conclusion, patient's knowledge and understanding and patient's satisfaction were assessed. The results showed there was no significant difference between the two groups regarding scores for anxiety and depression at time one and time two. There is some suggestion that the intervention reduced anxiety from trial conclusion to follow-up (P=0.27). Patients in both groups felt they had contributed to cancer research through trial participation. However, intervention patients were more likely to feel that they knew how the trial was going (P<0.001), knew how other people in the trial were doing (P=0.001), had all the feedback they needed about the trial they took part in (P<0.01) and knew how they would be followed up (P=0.02). Patient satisfaction with the intervention was high (median score=4.5 where 5 is greatest satisfaction). In conclusion, nurse-managed trial conclusion led to positive outcomes for patients who had recently completed a clinical trial.

Antineoplastic Agents↗
PubMed2005

Lack of EGF receptor contributes to drug sensitivity of human germline cells.

Germline mutations have been associated with generation of various types of tumour. In this study, we investigated genetic alteration of germline tumours that affect the drug sensitivity of cells. Although all germline tumour cells we tested were hypersensitive to DNA-damaging drugs, no significant alteration was observed in their DNA repair activity or the expression of DNA repair proteins. In contrast, germline tumours expressed very low level of epidermal growth factor receptor (EGFR) compared to drug-resistant ovarian cancer cells. An immunohistochemical analysis indicated that most of the primary germline tumours we tested expressed very low level of EGFR. In accordance with this, overexpression of EGFR in germline tumour cells showed an increase in drug resistance, suggesting that a lack of EGFR, at least in part, contributes to the drug sensitivity of germline tumours.

Blotting, Western↗
PubMed2004

Current injection electrodes for electrical impedance tomography.

Current conveyors have been identified as a possible component within the current injection electrodes of an electrical impedance tomography system, where accurate current generation or precise measurement of the current injected is required. Several circuit configurations have been investigated through simulation to determine the most suitable to meet the specifications of the EIT system. A bipolar (floating source) circuit configuration employing the use of current conveyors has been designed, which achieves greater than 12 mA output current without saturation, over an accepted body impedance range. Simulations were performed over frequencies in excess of 1 MHz, and the output phase shift was less than 0.15 degrees up to 250 kHz, and 0.6 degrees up to 1 MHz.

Electric Impedance↗
PubMed2003

The ownership signature in mouse scent marks is involatile.

Male house mice advertise their territory ownership through urinary scent marks and use individual-specific patterns of major urinary proteins (MUPs) to discriminate between their own scent and that of other males. It is not clear whether recognition occurs through discrimination of the non-volatile proteins or protein-ligand complexes (direct model), or by the detection of volatile ligands that are released from MUPs (indirect model). To examine the mechanism underlying individual scent mark signatures, we compared investigatory and countermarking responses of male laboratory mice presented with male scent marks from a strain with a different MUP pattern, when they could contact the scent or when contact was prevented by a porous nitrocellulose sheet to which proteins bind. Mice investigated scent marks from other males whether these were covered or not, and biochemical analysis confirmed that the porous cover did not prevent the release of volatiles from scent marks. Having gained information through investigation, mice increased their own scent marking only if they had direct contact with another male's urine, failing to do this when contact was prevented. Individual signatures in scent marks thus appear to be carried by non-volatile proteins or by non-volatile protein-ligand complexes, rather than by volatiles emanating from the scent.

Animal Communication↗
PubMed2003

Differences in polymorphonucleocyte function and local inflammatory response between horses and ponies.

REASONS FOR PERFORMING STUDY: Wound healing proceeds faster in ponies than in horses and complications during healing, such as wound infection, occur less frequently in ponies. Earlier studies suggested that this difference might be related to differences in the initial post traumatic inflammatory response. HYPOTHESIS: That polymorphonuclear leucocyte (PMN) function and profiles of humoral factors in local inflammatory processes are different in horses and ponies. METHODS: PMNs were isolated from venous blood of horses and ponies. Chemotaxis and reactive oxygen species (ROS) production was determined. Tissue cages were implanted in limbs and necks of horses and ponies and injected with carrageenan and, 3 weeks later, with LPS. In sequential samples of inflammatory exudate, the numbers of macrophages and PMNs and the production of PGE2, TNFalpha, IL-1, IL-6 and chemoattractants were determined. RESULTS: In vitro ROS production of PMNs was significantly higher in ponies than in horses, whereas in vitro PMN chemotaxis was significantly lower in ponies. In the tissue cages for both stimuli, the production of IL-1 and chemoattractants was significantly higher in ponies than in horses and remained so towards the end of the observation period in ponies. CONCLUSIONS: This study demonstrated a higher production of various inflammatory mediators by pony leucocytes. Despite the lower in vitro chemotaxis of pony PMNs, this higher in vivo production resulted in a stronger initial inflammatory response in ponies, as has been reported in studies on wound healing, through the attraction of leucocytes and triggering of the production of other cytokines. A stronger initial inflammation may promote healing by more rapid elemination of contaminants and earlier transition to repair. POTENTIAL RELEVANCE: Modulation of the initial inflammatory response might therefore be a valid option for therapeutic intervention in cases of problematic wound healing. Further, the intraspecies differences in leucocyte function may have an impact on many fields in equine medicine.

Animals↗
PubMed2002

Darbepoetin alfa given every 1 or 2 weeks alleviates anaemia associated with cancer chemotherapy.

In part A of this study, patients were randomised to cohorts receiving darbepoetin alfa at doses of 0.5 to 8.0 m.c.g x kg(-1) x wk(-1) or to a control group receiving epoetin alfa at an initial dose of 150 U x kg(-1) three times weekly. In part B, the cohorts were darbepoetin alfa 3.0 to 9.0 m.c.g x kg(-1) every 2 weeks or epoetin alfa, initial dose 40 000 U x wk(-1). Safety was assessed by adverse events, changes in blood pressure, and formation of antibodies to darbepoetin alfa. Efficacy was assessed by several haematologic endpoints, including change in haemoglobin from baseline. The adverse event profile of darbepoetin alfa was similar to that of epoetin alfa. No relationship between the rapidity of haemoglobin response and any adverse event was observed. No antibodies to darbepoetin alfa were detected. Higher doses of darbepoetin alfa increased the proportion of patients with a haemoglobin response and decreased the median time to response. The overall dose of darbepoetin alfa required to produce a mean increase in haemoglobin does not increase when the dosing interval is increased from 1 to 2 weeks. Therapy with darbepoetin alfa is safe and effective in producing a dose-related increase in haemoglobin levels in patients with cancer receiving chemotherapy.

Adult↗
PubMed2002

Randomised controlled trial of short bursts of a potent topical corticosteroid versus prolonged use of a mild preparation for children with mild or moderate atopic eczema.

OBJECTIVE: To determine whether a three day burst of a potent corticosteroid is more effective than a mild preparation used for seven days in children with mild or moderate atopic eczema. DESIGN: Randomised, double blind, parallel group study of 18 weeks' duration. SETTING: 13 general practices and a teaching hospital in the Nottingham area. PARTICIPANTS: 174 children with mild or moderate atopic eczema recruited from general practices and 33 from a hospital outpatient clinic. INTERVENTIONS: 0.1% betamethasone valerate applied for three days followed by the base ointment for four days versus 1% hydrocortisone applied for seven days. MAIN OUTCOME MEASURES: Primary outcomes were total number of scratch-free days and number of relapses. Secondary outcomes were median duration of relapses, number of undisturbed nights, disease severity (six area, six sign atopic dermatitis severity scale), scores on two quality of life measures (children's life quality index and dermatitis family impact questionnaire), and number of patients in whom treatment failed in each arm. RESULTS: No differences were found between the two groups. This was consistent for all outcomes. The median number of scratch-free days was 118.0 for the mild group and 117.5 for the potent group (difference 0.5, 95% confidence interval -2.0 to 4.0, P=0.53). The median number of relapses for both groups was 1.0. Both groups showed clinically important improvements in disease severity and quality of life compared with baseline. CONCLUSION: A short burst of a potent topical corticosteroid is just as effective as prolonged use of a milder preparation for controlling mild or moderate atopic eczema in children.

Administration, Topical↗
PubMed2002

Effects of carprofen (R and S enantiomers and racemate) on the production of IL-1, IL-6 and TNF-alpha by equine chondrocytes and synoviocytes.

Chondrocytes and synoviocytes harvested from the joints of healthy horses were maintained in tissue culture. Production of the cytokines interleukin-1 (IL-1), interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) in response to lipopolysaccharide (LPS), and the effects of addition of carprofen (racemate and R and S enantiomers) were determined. Lipopolysaccharide failed to stimulate TNF-alpha activity in both cell types but concentrations of IL-1 and IL-6 were both increased in a concentration and time-related manner. Both carprofen enantiomers and the racemic mixture attenuated the increase in IL-6 induced by LPS in synoviocytes, and S carprofen exerted a similar effect on chondrocytes. Neither enantiomer nor the racemate of carprofen suppressed the increase in IL-1 release produced by LPS in chondrocytes and synoviocytes. An action of carprofen to suppress IL-6 release might contribute to the actions which occur in vivo.

Animals↗
PubMed2002

A value clarification on quality within nursing colleges in Gauteng.

Quality assurance in higher education has been legislated. It is therefore necessary to develop a quality audit system for Nursing Colleges in Gauteng. The process of developing such a system is complex and needs to foster ownership by all the stakeholders. The first step in this process is to conduct a value clarification on quality. The purpose of this article is to explore and describe a value clarification on quality within the Nursing Colleges in Gauteng. An explanatory and descriptive qualitative research design was utilised. The results are grouped into structure, process and outcome values. Comparisons between the views of the different role-players are also presented. It is recommended that these results be utilised as the basis of a conceptual framework for the quality audit system for Nursing Colleges in Gauteng, as well as the development of quality indicators for Nursing Education Institutions in South Africa.

Education, Nursing, Baccalaureate↗
PubMed2001

Prophylactic platelet transfusions from healthy apheresis platelet donors undergoing treatment with thrombopoietin.

Many patients receiving dose-intensive chemotherapy acquire thrombocytopenia and need platelet transfusions. A study was conducted to determine whether platelets harvested from healthy donors treated with thrombopoietin could provide larger increases in platelet counts and thereby delay time to next platelet transfusion compared to routinely available platelets given to thrombocytopenic patients. Community platelet donors received either 1 or 3 microg/kg pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) or placebo and then donated platelets 10 to 15 days later. One hundred sixty-six of these platelet concentrates were then transfused to 120 patients with platelets counts 25 x 10(9)/L or lower. Pretransfusion platelet counts (11 x 10(9)/L) were similar for recipients of placebo-derived and PEG-rHuMGDF-derived platelets. Early after transfusion, the median platelet count increment was higher in patients receiving PEG-rHuMGDF-derived platelets: 19 (range, -12-66) x 10(9)/L, 41 (range, 5-133) x 10(9)/L, and 82 (range, -4-188) x 10(9)/L for placebo-, 1-microg/kg-, and 3-micro/kg-derived platelets, respectively. This difference was maintained 18 to 24 hours after transfusion. Transfusion-free intervals were 1.72, 2.64, and 3.80 days for the recipients of the placebo-, 1-microg/kg-, and 3-micro/kg-derived platelets, respectively. The rate of transfusion-related adverse events was not different in recipients of placebo-derived and PEG-rHuMGDF-derived platelets. Therefore, when transfused into patients with thrombocytopenia, platelets collected from healthy donors undergoing thrombopoietin therapy were safe and resulted in significantly greater platelet count increments and longer transfusion-free intervals than platelets obtained from donors treated with placebo.

Adolescent↗
PubMed2001

Application of a fluorometric assay for characterization of the catalytic competency of a domain III fragment of Pseudomonas aeruginosa exotoxin A.

Pseudomonas aeruginosa exotoxin A (ETA) is a member of the family of bacterial ADP-ribosylating toxins that use NAD(+) as the ADP-ribose donor. The reaction catalyzed by ETA involves the nucleophilic attack of the diphthamide residue on the anomeric carbon of the nicotinamide ribose forming a new glycosidic bond. A fluorometric assay involving the use of etheno-beta-nicotinamide adenine dinucleotide (epsilon-NAD(+)), an analog of NAD(+), has been found to provide a rapid, reliable, and sensitive procedure for assessing the kinetic parameters of this class of enzymes including ETA and its C-terminal fragment, PE24. Furthermore, application of this new assay facilitated the determination of the kinetic parameters for the protein substrate of ETA, elongation factor, which has previously been difficult to characterize. These findings provide new insights into catalytic mechanism of dipthamide-specific ribosyltransferases. In addition, this assay should also prove valuable for the study of NADases or NAD(+)-glycohydrolase enzymes (B. Weng, W. C. Thompson, H. J. Kim, R. L. Levine, and J. Moss, 1999, J. Biol. Chem. 274, 31797-31803; Y. S. Cho, M. K. Han, O. S. Kwark, M. S. Phoe, Y. S. Cha, N. H. An, and U. H. Kim, 1998, Comp. Physiol. B: Biochem. Mol. Biol. 120, 175-181) and the poly-ADP-ribosyltransferases (A. A. Pieper, A. Verma, J. Zhang, S. H. Snyder, 1999, Trends Pharmacol. Sci. 20, 171-181; M. K. Jacobson and E. L. Jacobson, 1999, Trends Biochem. Sci. 24, 415-417).

ADP Ribose Transferases↗
PubMed2001

Redo aortic root replacement: experience with 31 patients.

BACKGROUND: Aortic root re-replacement is being performed with increased frequency. Limited information is available regarding the surgical approaches and clinical outcomes of this reoperation. METHODS: Between May 1980 and May 1999, 31 patients (mean age, 45 +/- 15 years) underwent redo composite replacement of the aortic valve and ascending aorta. Indications for reoperation were prosthetic valve endocarditis in 12 patients (39%), failed biological valve in 17 (55%), and false aneurysm in 2 (6%). At reoperation, mechanical valves were implanted in 24 patients and biologic valves in 7. All patients with endocarditis had annular abscess and required reconstruction of the left ventricular outflow tract before implantation of a new valved conduit. Mechanical valves were used in 24 patients, aortic homograft in 4, and bioprosthetic valves in 3. The coronary button technique was used to reimplant the coronary arteries whenever possible. Extension of one or both coronary arteries with a short segment of saphenous vein or a synthetic graft was used in 16 patients (52%). The aortic arch was replaced in 7 patients (23%). RESULTS: There was one operative death (3%) because of rupture of an abdominal aortic aneurysm. The mean follow-up was 47 +/- 46 months and was 100% complete. There were five late deaths (16%), three of which were cardiac related. The actuarial survival was 71% +/- 12% at 5 years. Three patients experienced recurrent prosthetic valve endocarditis 4 months to 8 years after operation. The 8-year freedom from endocarditis for patients operated on for endocarditis was 82% +/- 11% compared with 100% for those operated on for other reasons (p = 0.1). At the last follow-up, 21 of 25 survivors (84%) were in New York Heart Association functional classes I or II, and 4 were in class III. CONCLUSIONS: Redo aortic root replacement can be performed with good early and late results. Patients operated on for prosthetic root endocarditis may have an increased risk of recurrent late endocarditis.

Adolescent↗
PubMed2001

The efficacy of the Cox/maze procedure combined with mitral valve surgery: a matched control study.

OBJECTIVE: To evaluate the results of the maze procedure combined with mitral valve (MV) surgery in patients with chronic atrial fibrillation (AF). METHODS: From 1994--1999, 47 patients with chronic AF underwent the maze procedure combined with MV surgery (maze group). They were compared to 47 patients matched for age, sex, left ventricular function and type of MV surgery (non-maze group). The maze group had less severe symptoms but larger left atrium, and AF of longer duration than the non-maze group. One surgeon performed all operations in both groups of patients. RESULTS: There were two early deaths in the maze group (4.5%) and one (2.2%) in the non-maze group. The duration of cardiopulmonary bypass (P=0.0001) and aortic crossclamping (P=0.0001) were greater in the maze group. Mean follow-up was 26+/-3 months in the maze group and 32+/-4 months in the non-maze group, and was 100% complete. Three-year survival was 96+/-3% for the maze group compared to 85+/-7% for the non-maze group (P=0.16). At the latest follow-up, 75% of the maze patients were in sinus rhythm compared to 36% of the non-maze patients (P=0.0004); 38% of the maze group were on coumadin postoperatively, compared to 69% in the non-maze group (P=0.003); and patients in the maze group were on fewer antiarrhythmic medications (P=0.0002). Three-year freedom from thromboembolic complications was 100% for the maze group compared to 83+/-7% for the non-maze group (P=0.03). CONCLUSIONS: In this retrospective study the maze procedure did not seem to increase operative mortality of MV surgery, was effective in eliminating atrial fibrillation, and reduced the risk of thromboembolic complications and the need for long-term anticoagulation after mitral valve repair or replacement with a bioprosthesis.

Aged↗
PubMed2001

Late results of heart valve replacement with the Hancock II bioprosthesis.

OBJECTIVE: To review the late clinical outcomes of patients who had isolated aortic or mitral valve replacement with the Hancock II bioprosthesis. METHODS: From 1982 to 1994, 670 patients underwent isolated aortic valve replacement and 310 underwent isolated mitral valve replacement with the Hancock II bioprosthesis (Medtronic Inc, Minneapolis, Minn). Mean age was 65 +/- 12 years in both groups. Most patients were in New York Heart Association functional classes III or IV, and concomitant coronary artery disease was present in 44% of patients in the aortic valve group and 41% of patients in the mitral valve group. Patients were followed up prospectively at periodic intervals. Mean follow-up was 87 +/- 45 months in the aortic valve group and 83 +/- 50 months in the mitral valve group, and it was 99% complete. RESULTS: Actuarial survival at 15 years was 47% +/- 3% in the aortic valve group and 30% +/- 5% in the mitral valve group. Older age, advanced functional class, impaired left ventricular function, active endocarditis, and coronary artery disease were independent predictors of late death. The freedom from thromboembolic complications at 15 years was 83% +/- 3% in the aortic and 87% +/- 3% in the mitral valve group. The freedom from infective endocarditis at 15 years was 96% +/- 1% in the aortic and 91% +/- 1% in the mitral valve group. At 15 years, the actuarial and actual freedom from structural valve deterioration was 81% +/- 5% and 90% +/- 3%, respectively, in the aortic group and 66% +/- 6% and 83% +/- 3%, respectively, in the mitral group. Younger age, mitral valve position, and poor ventricular function were independent predictors of structural valve deterioration. The freedom from repeat valve replacement at 15 years was 77% +/- 5% in the aortic group and 69% +/- 6% in the mitral. The vast majority of patients had functional improvement after valve replacement. CONCLUSIONS: The Hancock II bioprosthesis has provided good clinical outcomes and is a durable valve, particularly in the aortic position in older patients.

Adolescent↗