PubMed Health⌕ Search

Biomedical subjects

E Hurley

Publications and source records attributed to E Hurley.

13 recordsLinked to original sources
PubMed2005

Dual polarisation interferometry characterisation of DNA immobilisation and hybridisation detection on a silanised support.

Dual polarisation interferometry is an analytical technique that allows the simultaneous determination of thickness, density and mass of a biological layer on a sensing waveguide surface in real time. We evaluated, for the first time, the ability of this technique to characterise the covalent immobilisation of single stranded probe DNA and the selective detection of target DNA hybridisation on a silanised support. Two immobilisation strategies have been evaluated: direct attachment of the probe molecule and a more complex chemistry employing a 1,2 homobifunctional crosslinker molecule. With this technique we demonstrate it was possible to determine probe orientation and measure probe coverage at different stages of the immobilisation process in real time and in a single experiment. In addition, by measuring simultaneously changes in thickness and density of the probe layer upon hybridisation of target DNA, it was possible to directly elucidate the impact that probe mobility had on hybridisation efficiency. Direct covalent attachment of an amine modified 19 mer resulted in a thickness change of 0.68 nm that was consistent with multipoint attachment of the probe molecule to the surface. Blocking with BSA formed a dense layer of protein molecules that absorbed between the probe molecules on the surface. The observed hybridisation efficiency to target DNA was approximately 35%. No further significant reorientation of the probe molecule occurred upon hybridisation. The initial thickness of the probe layer upon attachment to the crosslinker molecule was 0.5 nm. Significant reorientation of the probe molecule surface normal occurred upon hybridisation to target DNA. This indicated that the probe molecule had greater mobility to hybridise to target DNA. The observed hybridisation efficiency for target DNA was approximately 85%. The results show that a probe molecule attached to the surface via a crosslinker group is better able to hybridise to target DNA due to its greater mobility.

Biosensing Techniques↗
PubMed1999

Outcomes of an educational-outreach service for community medical practitioners: non-steroidal anti-inflammatory drugs.

OBJECTIVE: Exploration of longer-term outcomes of an ongoing educational-outreach service for community doctors. DESIGN: Quasi-experimental, with parallel and historical comparisons. SETTING: Since 1992, a teaching-hospital-based service has been providing advice and information on drugs and therapeutic strategies to community medical practitioners. PARTICIPANTS: 210 doctors practising in a particular area of metropolitan Adelaide (79% general practitioners; 21% specialists). INTERVENTIONS: Two surgery visits during 1992 focused on better use of prescribed non-steroidal anti-inflammatory drugs (NSAIDs). Subsequent visits on other topical therapeutic issues have occurred regularly. MAIN OUTCOME MEASURES: Doctor participation in the service; supply of prescription NSAIDs; hospital admissions for gastrointestinal (GI) effects of NSAID use. RESULTS: 89% of doctors practising within the service area received the first visit on NSAIDs and 86% received the second visit. More than 85% continue to receive the service. Relative to a comparison area, aggregate reductions of 9% and 28%, respectively, were observed in two different measures of NSAID use. During an 11-year observation period, a single change point in the number of hospital admissions for GI disorders occurred in the service area, coinciding with delivery of the NSAID program. In the five years since the visits commenced, a 70% reduction in admissions was observed. No notable changes in hospital admission rates occurred in the comparison area. CONCLUSIONS: A continuing education and support service for community medical practitioners which uses principally academic detailing methods in its contact with doctors has contributed to sustained changes in prescribed NSAID use over a five-year period. A focus on risk-minimisation in prescribing of NSAIDs appears to have contributed to reductions in hospitalisations for GI adverse events.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

Fracture strengths of provisional restorations reinforced with plasma-treated woven polyethylene fiber.

STATEMENT OF PROBLEM: Fracture strength of interim fixed partial prosthesis is of great concern, especially in long-span restorations or areas of heavy occlusal stress. PURPOSE: Effects of a plasma-treated woven polyethylene fiber (Ribbond) on the fracture strength of polymethyl methacrylate (Coldpac) and a resin-based two-phase curing provisional restorative material (Provipont DC) were evaluated. MATERIAL AND METHODS: A polyvinyl siloxane template was used to fabricate three-unit posterior provisional prostheses on a stainless steel die with two abutments 22 mm apart. The reinforced groups were fabricated by affixing 3 mm wide pieces of fiber treated with methyl methacrylate monomer or polyisocyanate (activator part of Provipont DC) on the occlusal surfaces of abutments. The interim materials were mixed, according to the manufacturers' specifications, and placed in the template. The template was pressed on the die and held secure until complete setting of the material occurred by light curing (Provipont DC) or autopolymerization (PMMA). The specimens were divided into 4 groups of 10 each (A, reinforced Provipont DC; B, unreinforced Provipont DC; C, reinforced PMMA; and D, unreinforced PMMA). A central compressive load force was exerted on the specimen to determine the fracture load of the restorations. RESULTS: The data revealed mean fracture loads of A, 65.59 +/- 11.27 kg; B, 46.59 +/- 14.84 kg; C, 53.46 +/- 7.76 kg; and D, 49.86 +/- 14.44 kg. CONCLUSION: Plasma-treated polyethylene reinforced PMMA restorations showed no significant increase in fracture loads when compared with unreinforced restorations (p > 0.10), whereas reinforced resin-based restorations revealed significantly higher fracture loads (p < 0.01) than the unreinforced resin-based and PMMA provisional restorations.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1997

In vitro comparison of restoration wear and tensile strength following extended brushing with Sonicare and a manual toothbrush.

The purpose of this study was to compare the wear, cement margin breakdown and bond strength of restorations following 6 to 12 months of simulated use in vitro of the Sonicare and a manual toothbrush. Extracted molar teeth with Class V hybrid composite resin restorations (n = 21) or with Class V gold inlays cemented with zinc phosphate cement were tested for wear and marginal integrity following brushing for a period that simulated 6 months of typical use. One-third of the molars in each group were brushed with the Sonicare and one-third were brushed with the manual brush. The remaining third served as non-treated controls. Toothbrushing was performed under a standardized load using a piston-action brushing machine. After brushing, the enamel, dentin/cementum and restorations were examined by light and scanning electron microscopy. There was no apparent wear of tooth structure or of restorative materials with either the Sonicare or the manual brush. There was a small loss of cement from the margins of the gold inlays following toothbrushing, which was similar and not significantly different between the sonic and manual brush. To test brushing effects on crown retention, four identical metal dies were prepared to simulate premolar crown preparations. Thirty cast copings, prepared to fit the dies, were cemented with zinc phosphate cement. Toothbrushing with Sonicare or the manual toothbrush was performed as before (n = 15 for each brush), but the simulated time was extended to the equivalent of 1 year of brushing. The dislodgement force of cemented crowns was not significantly different (t-test, p > 0.10) between the manual (207 +/- 69 N) and Sonicare (221 +/- 61 N) groups. These results demonstrate that despite its high frequency bristle motion, Sonicare exerts no detrimental effects on cement margin integrity, crown bond strength or surface wear of dental and restorative materials.

Analysis of Variance↗
PubMed1996

Cyclosporin A and multiple fibroadenomas of the breast.

Multiple bilateral fibroadenomas are uncommon. This finding in four women who had received renal transplants prompted further inquiry. A prospective study was performed on 39 women under the age of 55 years who had received a renal transplant at least 1 year earlier. Clinical examination and breast ultrasonography were performed. Factors considered included immunosuppressive therapy, concurrent medication and renal function. Blood was taken for estimation of oestradiol, prolactin, follicle-stimulating hormone (FSH) and sex hormone binding globulin levels. Fibroadenomas were found in 13 of 29 women who had received cyclosporin A: multiple in ten and bilateral in five. No abnormal breast findings were seen in 10 patients immunosuppressed with steroids and azathioprine alone (chi 2 = 7.30, 1 d.f., P < 0.01). Serum oestradiol concentration was raised in women with fibroadenomas compared with that in those with normal breasts (P < 0.05) and the level of FSH was lower (P < 0.01). Cyclosporin A may act on breast fibroblasts by humoral mechanisms and direct action.

Adult↗
PubMed1996

The role of helper lipids in cationic liposome-mediated gene transfer.

In the procedure for cationic liposome-mediated transfection, the cationic lipid is usually mixed with a "helper lipid" to increase its transfection potency. The importance of helper lipids, including dioleoylphosphatidylcholine (DOPC) and phosphatidylethanolamine (dioleoyl PE), DO was examined. Freeze-fracture electron microscopy of DNA:cationic complexes containing the pSV-beta-GAL plasmid DNA, the cationic lipid dioleoyl trimethylammonium propane, and these helper lipids showed that the most efficient mixtures were aggregates of ensheathed DNA and fused liposomes. PE-containing complexes aggregated rapidly when added to culture media containing polyanions, whereas PC-containing complexes did not. However, more granules of PC-containing complexes were formed on cell surfaces after the complexes were added to Chinese hamster ovary (CHO) cells in transfection media. Pronase treatment inhibited transfection, whereas dilute poly-L-lysine enhanced transfection, indicating that the attachment of DNA:liposome complexes to cell surfaces was mediated by electrostatic interaction. Fluorescence spectroscopy studies confirmed that more PC-containing complexes than PE-containing complexes were associated with CHO cells, and that more PC-containing complexes were located in a low pH environment (likely to be within endosomes) with time. Cytochalasin-B had a stronger inhibitory effect on PC-containing liposome-mediated than on PE-containing liposome-mediated transfection. Confocal microscopic recording of the fluorescently label lipid and DNA uptake process indicated that many granules of DNA:cationic liposome complexes were internalized as a whole, whereas some DNA aggregates were left out on the cell surfaces after liposomes of the complexes fused with the plasma membranes. For CHO cells, endocytosis seems to be the main uptake pathway of DNA:cationic liposome complexes. More PC-containing granules than PE-containing granules were formed on cell surfaces by cytoskeleton-directed membrane motion, after their respective DNA:liposome complexes attached to cell surfaces by electrostatic means. Formation of granules on the cell surface facilitated and/or triggered endocytosis. Fusion between cationic liposomes and the cell membrane played a secondary role in determining transfection efficiency.

Animals↗
PubMed1996

Class II composite resin restorations using glass-ionomer liners: microleakage studies.

Microleakage studies were undertaken for Class II composite resin restorations that had been lined with glass-ionomer cement using the 'sandwich' technique. Thirty freshly extracted permanent molars and premolars were mounted in polymethylmethacrylate blocks. Class II cavities were prepared using carbide burs No. 245 in a water cooled dental handpiece, (cavity box 5 x 3 x 2 mm). Specimens were divided into three groups of 10 each. Group A was restored with hybrid composite resin only, Group B with hybrid composite using a light-cured glass-ionomer liner applied to dentin only, and Group C with hybrid composite using light-cured glass-ionomer liner carried out to the cavosurface margin, (beyond the DEJ). All the specimens were thermocycled between 5 degrees C and 55 degrees C for 250 cycles for 3 hours, followed by placement in 0.5% aqueous basic fuchsin dye for 24 hours at 37 degrees C. Specimens were sectioned mesio-distally through the restorations using an Isomet apparatus. The extent of dye penetration was scored under a stereomicroscope with reference to the DEJ, (0 = no penetration, 1 = penetration to the enamel, 2 = penetration beyond the DEJ). Statistical analysis of the data showed significant differences among the means of the groups at p < 0.001. The results of this study indicate that the application of a light-cured glass-ionomer up to the cavosurface margin inhibits the microleakage of Class II restorations in vitro.

Bicuspid↗
PubMed1992

Human T-cell lymphotropic virus (HTLV)-related endogenous sequence, HRES-1, encodes a 28-kDa protein: a possible autoantigen for HTLV-I gag-reactive autoantibodies.

The presence of a human T-cell lymphotropic virus (HTLV)-related endogenous sequence, HRES-1, in the human genome has been documented. The HRES-1 genomic locus is transcriptionally active and contains open reading frames. Antibodies 232 and 233, specific for synthetic peptides pep14-24 and pep117-127, corresponding to two nonoverlapping HTLV-related regions in the longer open reading frame of HRES-1, recognize an identical 28-kDa protein in H9 human T cells. Thus, HRES-1 is a human endogenous retroviral sequence capable of protein expression. HRES-1/p28 is localized to the cytoplasm and nuclear bodies. While HTLV-I-specific antibodies react with HRES-1 peptides, antibody 233 cross-reacts with HTLV-I gag p24 protein. Three consecutive highly charged amino acid residues, Arg-Arg-Glu, present in both HRES-1 pep117-127 and HTLV-I gag p24 are likely to be the core of cross-reactive epitopes. The prevalence of antibodies to HRES-1 peptides pep14-24 and pep117-127 was determined in 65 normal blood donors and 146 patients with immunological disorders. Sera of patients with multiple sclerosis (19 out of 65, 29%), progressive systemic sclerosis (4 out of 17, 23%), systemic lupus erythematosus (4 out of 19, 21%), and Sjogren syndrome (2 out of 19, 10%) contained significantly higher HRES-1 peptide binding activity than sera of normal donors. Sera of patients with AIDS showed no specific binding to HRES-1 peptides. Nine of 30 HRES-1-seropositive patients showed immunoreactivity to HTLV-I gag p24. The data indicate that HRES-1/p28 may serve as an autoantigen eliciting autoantibodies cross-reactive with HTLV-I gag antigens.

Amino Acid Sequence↗
PubMed1987

Immature dense granules in platelets from mice with platelet storage pool disease.

Mepacrine uptake into platelets and bone marrow megakaryocytes was analyzed to further characterize the dense granule defects in a group of seven mouse pigment mutants that have characteristics of platelet storage pool disease (SPD). In contrast to our previous studies using electron microscopy, this method revealed that all mutants had normal numbers of dense granules. However, total mepacrine uptake in all mutant platelets was significantly diminished to less than 50% of normal uptake. Also, the flashing phenomenon observed when normal dense granules are irradiated with ultraviolet light was either greatly diminished or absent when platelets of individual mutants were similarly irradiated. Therefore the principal defect in the mutant platelets is an inability to accumulate dense granule contents rather than an absence of the granules. Mepacrine uptake into megakaryocytes was indistinguishable in normal and mutant mice. This indicates the mutant dense granule defects appear either very late in megakaryocyte development or early in platelet formation in correlation with development of the mature dense granule. By standard transmission electron microscopy we have not been able to detect gross structural or subcellular abnormalities in either platelets or megakaryocytes of mutant mice. It appears all seven mutants produce immature or functionally abnormal dense granules.

Animals↗
PubMed1977

Effects of isolated right and left ventricular stretch on regional arteriolar resistance.

In order to evaluate right and left ventricular stretch receptors without concomitantly stimulating those of the contralateral ventricle, 12 dogs were placed on total cardiopulmonary bypass. Balloons connected to compliant reservoirs were introduced into the right and left ventricles. Changes in systemic, gracilis muscle, and paw perfusion pressure at a constant flow were used as indices of systemic, muscle, and cutaneous vascular resistance. To induce left ventricular stretch, the balloon in that chanber was rapidly inflated from a mean pressure of 1.33 kPa (10 mmHg) to a mean pressure of 7.32 kPa (55 mmHg) for 15s (6.00 kPa [45mmHg] increment). For right ventricular stretch, the pressure was increased from 0.67 to 4.00 kPa (5 to 30 mmHg) for 30 s (3.34 kPa [25 mmHg] increment). Both left and right ventricular stretch produced a significant fall in systemic (-4.92 kPa [-37 mmHg], -36%) and gracilis muscle (-5.59 kPa [-42 mmHg], -30%) perfusion pressure, with only minimal changes in cutaneous vascular resistance (-0.80 kPa [-6 mmHg], -4%). This reflex was found to be vagally mediated, to have a low threshold for stimulation (left ventricle, 0.67 kPa [5 mmHg] increment; right ventricle, 1.33 kPa [10 mmHg] increment), and to have a neurogenic sympathetic alpha-adrenergic efferent limb. The low threshold for stimulation suggests that these reflexes may play a physiological role with changes in body position and may be important in such pathological conditions as semilunar valvular stenosis and myocardial infarction.

Animals↗
PubMedDate not supplied

Effects of fabrication, finishing, and polishing procedures on preload in prostheses using conventional "gold' and plastic cylinders.

This study reviews fundamental concepts related to the use of screws and presents data describing the effect of fabrication, finishing, and polishing procedures on as-received preload for implant cylinders. Specifically, this study measured and compared preload produced when using as-received gold cylinders (the reference or gold standard), and cast cylinders produced from premade gold and plastic cylinders in the as-cast condition and following postcast finishing and polishing manipulations. The results reveal that preload in the gold screw-gold cylinder-abutment joint can be affected by the casting process, and that the choice of cylinder type, casting alloy, investment, and finishing/polishing technique may affect the resultant preload as compared to as-received joint conditions. The data from this study indicate that when plastic patterns are used as part of the framework, finishing and polishing of implant cylinder components should provide an increased preload compared to no such manipulations. Also, if maximum preload is desired, the use of premade metal cylinders offers an advantage over plastic patterns in both preload magnitude and precision.

Dental Abutments↗