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Biomedical subjects

G Harrington

Publications and source records attributed to G Harrington.

At least 19 recordsLinked to original sources
PubMed2004

Risk factors for acquisition of methicillin-resistant Staphylococcus aureus (MRSA) by trauma patients in the intensive care unit.

In a previous study in the intensive care unit (ICU) of the Alfred Hospital, Melbourne, Australia, it was demonstrated that trauma patients were at particular risk of becoming colonized by methicillin-resistant Staphylococcus aureus (MRSA). We examined risk factors for MRSA acquisition in these patients using a cohort study comparing the 31 patients who acquired MRSA with 65 who did not. Data collected included ICU length of stay (LOS), mechanism of trauma, site of injury, type of surgery, trauma severity and antibiotic usage. Odds ratios (OR) were determined and adjusted for LOS. LOS in the ICU was a significant univariate predictor of MRSA acquisition (OR 13.7). When adjusted for LOS, mechanism of trauma (OR 10.4), laparotomy (OR 6.3) and administration of ticarcillin/clavulanic acid (OR 4.5) or glycopeptides (OR 5.9) remained significant. We confirmed our previous finding that LOS was associated with MRSA acquisition. Receipt of antibiotics correlated with reported literature. Novel associations were road trauma as a mechanism and laparotomy.

Accidents, Traffic↗
PubMed2004

Rate of nosocomial transmission of vancomycin-resistant enterococci from isolated patients.

To evaluate an isolation policy for patients colonised with vancomycin-resistant enterococci (VRE), we instituted active surveillance for transmission to uncolonised patients. Surveillance rectal swabs were taken and pulsed-field gel electrophoresis was performed on positive isolates. VRE transmission with an identical genotype occurred in 5 patients, giving a transmission rate of 3.7 per 1000 patient days, or 1 patient per ward each week. The present study provides a baseline for -assessment of VRE transmission and will be useful in evaluation of the effectiveness of infection control interventions.

Cross Infection↗
PubMed2000

Investigation of amine and polyol functionality in extracts of polyurethane wound management dressings using MALDI-MS.

Polyurethane (PU) foams used in wound management are produced by a reaction between aromatic diisocyanates and polyether polyols. There is concern that residues of these starting materials, which may contain aromatic amine functionality, may leach from the finished polymer during in vivo applications. Furthermore, oligomers and additives may be leached from the PU system after the polymerization process is complete. Finished polymers have, therefore, been extracted with a range of solvents, such as water, diethyl ether and dilute HCl. The extracts were subjected to MALDI-MS (matrix-assisted laser desorption ionization mass spectrometry) analysis in an attempt to determine the amine and polyol functionality. Direct MALDI-MS analysis of the wound dressing extracts indicated the presence of components based on the polyols [corrected] used in the formulation of the foam. The spacing between the peaks identified the base monomer used in the polyol. MALDI-MS analysis of the fluorescamine derivatives of model amine compounds has demonstrated the anticipated increase in mass (278 for monoamines and 278 and 556 for diamines). Similar results were obtained from the derivatization of model polyols with phenyl isocyanate, where the mass shift (n x 119) was a direct measure of the number of active hydroxyl groups. Fluorescamine labelling of PU foams shows the colour change which could be [corrected] indicative of the presence of an amine, but the subsequent MALDI-MS analysis was unable to demonstrate the anticipated increase in mass.

Amines↗
PubMed2000

Risk factors for surgical wound infection and bacteraemia following coronary artery bypass surgery.

BACKGROUND: There has been no consensus from previous studies of risk factors for surgical wound infections (SWI) and postoperative bacteraemia for patients undergoing coronary artery bypass graft (CABG) surgery. METHODS: Data on 15 potential risk factors were prospectively collected on all patients undergoing CABG surgery during a 12-month period. RESULTS: Of 693 patients, 62 developed 65 SWI using the Centres for Disease Control definition: 23 were sternal wound infections and 42 were arm or leg wound infections at the site of conduit harvest. There were 19 episodes of postoperative bacteraemia. Multivariate analysis revealed that: (i) diabetes, obesity and previous cardiovascular procedure were independent predictors of SWI; and (ii) obesity was an independent risk factor for postoperative bacteraemia. CONCLUSIONS: These findings suggest that improved diabetic control and pre-operative weight reduction may result in a decrease in the incidence of SWI. But further prospective studies need to be undertaken to examine (i) whether the increased SWI risk in diabetes occurs with both insulin- and non-insulin-requiring diabetes, and whether improved peri-operative diabetes control decreases SWI; and (ii) what degree of obesity confers a risk of SWI and postoperative bacteraemia, and whether pre-operative weight reduction, if a realistic strategy in this patient group, results in a decrease in SWI.

Bacteremia↗
PubMed2000

Effluxes of solutes from developing seed coats of Phaseolus vulgaris L. and Vicia faba l.: locating the effect of turgor in a coupled chemiosmotic system.

Cells lining the developing seed coats of legumes efflux photosynthates (mostly sucrose) and salts (mostly of potassium) into the apoplast for uptake by the developing embryo. These effluxes increase transiently in response to an increase in turgor in the effluxing cells. Detached coats of developing seed of P. haseolus vulgaris and Vicia faba were used to study the effects of turgor on the rates of efflux, on the membrane potential difference and on the membrane pH difference, using a number of inhibitors and agents which might affect signal cascades involving cytoplasmic calcium concentration. Effluxes were measured by measuring the concentrations of solutes of interest in solution samples placed in halves of detached seed coats, the paired halves serving as control and treated sample where appropriate. It is shown that a number of substances affect sucrose and potassium effluxes differently, and that hypo-osmotic shock depolarizes the efflux cells and acidifies the cytoplasm (in P. vulgaris). It is concluded that sucrose and potassium effluxes, although both are increased by an increase in turgor, are affected by different signal pathways. Further, it is also concluded that the signal that increases the rates of both sucrose efflux (via sucrose-proton antiport) and proton pump acts directly on the antiporter rather than on the pump. There are interesting parallels and contrasts between these processes and those in plants such as the charophyte Lamprothamnium after hypo-osmotic shock.

Calcium↗
PubMed1999

A cost-analysis of two approaches to infection control in a lung function laboratory.

BACKGROUND: The Thoracic Society of Australia and New Zealand (TSANZ) guidelines for infection control in respiratory laboratories are based on a 'Universal Precautions' approach to patient care. This requires that one-way breathing valves, flow sensors, and other items, be cleaned and disinfected between patient use. However, this is impractical in a busy laboratory. The recent introduction of disposable barrier filters may provide a practical solution to this problem, although most consider this approach to be an expensive option. AIM: To compare the cost of implementing the TSANZ infection control guidelines with the cost of using disposable barrier filters. METHODS: Costs were based on the standard tests and equipment currently used in the lung function laboratory at The Alfred Hospital. We have assumed that a barrier filter offers the same degree of protection against cross-infection between patients as the TSANZ infection control guidelines. Time and motion studies were performed on the dismantling, cleaning, disinfecting, reassembling and re-calibrating of equipment. Conservative estimates were made as to the frequency of replacing pneumotachographs and rubber mouthpieces based on previous equipment turnover. Labour costs for a scientist to reprocess the equipment was based on $20.86/hour. The cost of employing a casual cleaner at an hourly rate of $14.07 to assist in reprocessing equipment was also investigated. The new high efficiency HyperFilter disposable barrier filter, costing $2.95 was used in this cost-analysis. RESULTS: The cost of reprocessing equipment required for spirometry alone was $17.58 per test if a scientist reprocesses the equipment, and $15.56 per test if a casual cleaner is employed to assist the scientist in performing these duties. In contrast, using a disposable filter would cost only $2.95 per test. Using a filter was considerably less expensive than following the TSANZ guidelines for all tests and equipment used in this cost-analysis. CONCLUSIONS: The TSANZ infection control guidelines are expensive and impractical to implement. However, disposable barrier filters provide a practical and inexpensive method of infection control.

Australia↗
PubMed1998

Fulminant progression of demyelinating disease after valproate-induced encephalopathy.

We report the clinical, radiologic, and pathologic features of a patient who had fulminant demyelinating disease and who experienced acute progression of his disease after an episode of valproate-induced hyperammonemic encephalopathy. The role hyperammonemia played in the progression of the demyelination is uncertain. This case raises concern of a possible risk with the use of valproic acid in the subset of patients with fulminant demyelinating disease.

Adult↗
PubMed1997

Line extension.

Explore the source record for details and available documents.

Canada↗
PubMed1996

Defibrillation success is associated with myocardial organization. Spatial coherence as a new method of quantifying the electrical organization of the heart.

The relationship between the degree of electrical organization of ventricular fibrillation (VF) and defibrillation success was investigated in this study using a new technique to quantify organization--spatial coherence. This technique employs the use of the magnitude-squared coherence spectrum to analyze multichannel electrograms obtained during a cardiac mapping study. Magnitude-squared coherence values for all possible pairs of electrograms recorded from an epicardial plaque consisting of 112 electrodes were computed. Average coherence was plotted versus electrode separation distance, and the data were fit with an exponentially decaying curve. Two parameters indicative of myocardial organization were extracted from the curve. The coherence length (d) was defined as the distance (mm) at which the average coherence dropped to a given level, and the coherence strength was defined as the average coherence value at a given distance. Higher values for these parameters were hypothesized to indicate higher levels of organization. The spatial coherence technique was tested previously in a canine study of ventricular fibrillation (VF) and normal sinus rhythm, and the results suggested that spatial coherence parameters may be used to compare cardiac rhythms in terms of their organization. To test the hypothesis that organization is related to defibrillation success, 164 mapping sessions recorded during repeated VF induction and defibrillation trials using a monophasic waveform were performed in a close-chested canine study (n = 9) using a fixed energy and VF duration (10 seconds). Three coherence lengths and five coherence strengths were calculated for each VF episode. Results using a two-way analysis of variance with blocking between dogs showed that all of the coherence length and three of the coherence strength parameters were higher for those VF episodes that were successfully defibrillated than for those that were not (P < .05). Energy delivered and transmyocardial impedance were not significantly different between the groups. The authors conclude (1) the organization of a VF episode, as reflected in the spatial coherence parameters, is related to defibrillation success and may be partially responsible for the probabilistic nature of defibrillation and (2) the spatial coherence technique provides a means of quantifying myocardial electrical organization and is an important experimental tool that may be used to obtain a better understanding of VF and its termination.

Animals↗
PubMed1996

Marginal leakage of cast gold crowns luted with zinc phosphate cement: an in vivo study.

Marginal gaps of cast restorations are filled with luting agents that are soluble in intraoral fluids. This study investigated the marginal openings in eight extracted teeth with cast crowns that had been intraoral for 20 years or more. These teeth were extracted either because of periodontal disease or to facilitate insertion of a removable partial denture. Initially, the roots of the teeth were sealed with two coats of fingernail polish within 2 mm of the crown-tooth interface. Next, the teeth were immersed in a 0.05% aqueous solution of basic fuchsin die for 24 hours. Finally, each tooth was sectioned at four locations 1 mm apart. At each of these four sections, cement film thickness between tooth and casting, and microleakage were determined. The results of this study showed a mean cement film thickness of 74 microns on the mesial surface and 57 microns on the distal surface. Mean microleakage values were 432 microns on the mesial surface and 274 microns on the distal surface.

Adult↗
PubMed1996

Investigation of an apparent cluster of Klebsiella pneumoniae bacteremias using random amplified polymorphic DNA analysis.

A cluster of bacteremia episodes with Klebsiella pneumoniae was noted in patients in a hematology-oncology ward during a 3-week period. Random amplified polymorphic DNA (RAPD) analysis, a novel technique for generating chromosomal fingerprints from bacterial isolates, was used as an aid to the epidemiological investigation of this cluster. For each of the two patients from whom multiple isolates had been obtained, identical RAPD patterns were observed in the serial isolates, even for a patient where the isolates had different biotypes. Isolates from different patients gave distinct patterns. Random amplified polymorphic DNA was found to be a useful typing technique for this cluster of K pneumonia bacteremias.

Bacteremia↗
PubMed1996

Improved nonthoracotomy defibrillation based on ventricular fibrillation waveform characteristics.

The heart has been shown to be more susceptible to defibrillation at a higher absolute ventricular fibrillation voltage (AVFV) measured on the surface ECG. This study evaluated in a closed-chest canine model (n = 7) the clinical applicability of using a real-time VF waveform analysis system using an electrogram defined between the generator can and an RV endocardial electrode. Under fluoroscopic guidance, superior vena cava and RV spring coil catheter electrodes were inserted through the external jugular vein. A subcutaneous patch was placed on the left chest. A two-parameter tracking algorithm was used to dynamically identify the high AVFV area, and a biphasic shock was triggered synchronously at the next peak. The performance of this new peak shock method (PSM) was compared to the conventional method of shocking at a fixed time in 175 paired trials. Five shocks per voltage and five voltages per animal were randomized between the two methods to permit the generation of sigmoidal dose response curves for the estimation of 50% (E50), 75% (E75), and 100% (E100) success energies. Induction of VF and discharge voltage were kept constant while energy delivered, impedance (R), and AVFV at the point of shock were measured. Energy (8.63 +/- 0.40 vs 8.64 +/- 0.40 J), R (48.60 +/- 0.30 vs 48.59 +/- 0.30 omega), and current (7.50 +/- 0.18 vs 7.51 +/- 0.16 A) were not significantly different between trials for either the conventional or the PSM. The time from the onset of VF until the defibrillation shock was 7.98 +/- 1.44 seconds. Higher overall successes (46.3% vs 33.1%; P < 0.01) and lower E50, E75, and E100 were observed for the PSM. Finally, the significantly higher AVFV (9.12 +/- 0.32 vs 4.73 +/- 0.34 mV; P < 0.0001) with the peak method suggests that the high VF voltage could be detected as it occurred in real-time. The improved defibrillation success supports the use of this method for nonthoracotomy defibrillation.

Animals↗
PubMed1988

Catheter infection. A comparison of two catheter maintenance techniques.

Incidence of catheter-related infections was studied using two techniques: changing catheters over a guide-wire or placing a new catheter at a new site every 3 days. Patients were randomized into two groups: Group 1 (new site) and Group 2 (guide-wire). Of the 105 catheterization sites (20 arterial and 85 central lines) in patients of Group 1, none were considered infected (i.e., having 15 or more colonies at the time of semi-quantitative microbiology analysis and clinical signs of infection at the catheter site). Of the 274 catheterization sites (56 arterial and 218 central) of patients of Group 2, eight (2.9%) were infected (chi 2 = 1.89, p greater than 0.05). Colonization (15 or more cultures without clinical signs of infection) occurred in three of 105 (2.9%) and in four of 274 (1.5%) of the catheterization sites of Groups 1 and 2, respectively (chi 2 = 0.23, p greater than 0.05). Study results indicate no significant difference in infection or colonization rates between the two methods of catheter replacement.

Adolescent↗
PubMed1985

Superoxide dismutase and peroxidase are coordinately regulated in differentiated and transformed tissues of Nicotiana tabacum.

We used a series of normal and Agrobacterium-transformed, bacteria-free tobacco tissue cultures which differ in their levels of histodifferentiation to test the relationship of superoxide dismutase, peroxidase, and catalase to oncogenic transformation and differentiation. When compared with normal callus, tumor callus contained reduced levels of both superoxide dismutase and peroxidase, and a reduced number of isozymes of both enzymes. Teratomas characterized by limited but abnormal differentiation showed increases in superoxide-dismutase activity and isozymes, but levels of peroxidase activity lower than those found in normal callus despite an increase in the number of peroxidase isozymes. A similar disparity between low peroxidase activity and high isozyme number in the shoot suggests that there are increased levels of peroxidase inhibitors or of molecules which interfere with the spectrophotometric assay for peroxidase in more differentiated tissues. As judged by the number of isozymes of both superoxide dismutase and peroxidase in each tissue, the following conclusions are warranted: first, tobacco copper/zinc superoxide dismutases and peroxidases are encoded in several duplicated loci which are regulated independently. Second, transformation is associated with a decrease in both the specific activity and isozyme number of superoxide dismutase. Third, the partial release from the total inhibition of expression of differentiated function exhibited by teratoma is associated with an increase in both the activity and isozyme number of superoxide dismutase. Finally, the expression of superoxide dismutase and peroxidase isozymes appears to be coordinated during differentiation in a manner that is consistent with their role in an integrated mechanism for the removal of reduced oxygen species.

Catalase↗
PubMed1976

Hypophosphatasia. Review of 24 cases.

Radiographic analysis of 24 cases of hypophosphatasia (H) from 9 Paediatric Centres was performed. 3 cases were of neonatal (lethal), 18 cases of infantile (severe) and 3 cases of late (benign) type. Some of the patients were in reality borderline cases between these groups. In the authors' material all the patients showed radiographic signs of the disease. These were divided into diagnostic, characteristic and suggestive features. All of the patients had in common generalised (usually irregular) osteoporosis, generalised (usually irregular) metaphyseal changes, craniostenosis (13 of 18 infantile cases) or widened cranial sutures and ofter bowing of the long bones. Besides the well know radiographic features of hypophosphatasia some less well known, rare or 'new' ones such as, 1. spurs of the long bones (Bowdler sign), 2. distal femoral central metaphyseal defects and epiphyseal defects, 3. S-like deformities of the tibiae, 4. abnormal shape of the distal phalanges of the fingers, 5. multiple rib fractures and slender bones, 6. wedging of the lower thoracic and upper lumbar vertebrae, 7. partial premature fusion of the epiphyses, 8. nephrocalcinosis, 9. loss of lamina dura around the teeth, 10. variation in radiographic appearances of a pair of siblings with lethal form, and, 11. rapid changes in roentgen appearances. are discussed. In two of our patients (siblings) phosphoethanolamine was undetectable in the urine. The authors doubt if a normal skeletal survey may be present at any stage in any of the three major types of hypophosphatasia.

Adolescent↗