Search PubMed⌕ Search

Biomedical subjects

D Lee

Publications and source records attributed to D Lee.

At least 19 recordsLinked to original sources
PubMed2006

Combined endovenous laser therapy and ambulatory phlebectomy: refinement of a new technique.

OBJECTIVE: Sclerotherapy (IS) or ambulatory phlebectomy (AP) are required as subsequent interventions in majority of cases following endovenous laser therapy (EVLT). We assessed whether AP performed concomitantly with EVLT (EVLTAP), is effective, acceptable, and reduces subsequent requirement for interventions. METHOD: 67 patients (70 limbs) with great saphenous varicosities underwent EVLTAP. Pain was assessed on days 1, 4 and 7 using a visual analogue scale (VAS) of 0 to 10. Clinical and ultrasound assessments were done at 1, 6 and 12 weeks (no ultrasound at 6 weeks). Residual varicosities underwent further AP or IS. Patients' satisfaction with the cosmetic outcome and overall treatment was assessed at 12 weeks using a VAS rating. RESULTS: 49 patients (70%) completed follow-up. Median pain scores were 1.6 (IQR 0.2-4.8), 0.3 (0-1.4) and 0.2 (0-1.1) on days 1, 4 and 7 respectively. Ultrasound demonstrated 69 (99%) and 47 (96%) occluded long saphenous veins at 1 and 12 weeks respectively. Subsequent IS or AP was performed on 3 (4%) or 1 (1%) limbs respectively. Cosmetic satisfaction was 9.6 (IQR 8.9-10) and overall satisfaction 9.8 (IQR 9.3-10). CONCLUSION: EVLTAP produces excellent results, is feasible and acceptable, and obviates need for subsequent procedures in the short-term.

Adult↗
PubMed2006

Fiber-optic color synthesizer.

Full-color synthesis was achieved, for what we believe is the first time, utilizing a novel 3x1 hard polymer-clad fiber coupler along with red, green, and blue (RGB) LED primaries. By using RGB LEDs that are coupled to three input ports, the device rendered full color from the output port with a circular emitting pixel of 135 microm in diameter with an extended color gamut. The proposed fiber-optic color synthesizer can provide a compact waveguide solution for the beam scanning display and the tunable pure white source for LED backlighting.

Journal Article↗
PubMed2006

Thermoluminescence emission spectra for the LiF:Mg,Cu,Na,Si thermoluminescent materials with various concentrations of the dopants (3-D measurement).

The thermoluminescence (TL) emission spectra from LiF TL materials, called KLT-300 (LiF:Mg,Cu,Na,Si) with various dopant concentrations are measured and analysed. These KLT-300 materials were developed by the Korea Atomic Energy Research Institute (KAERI) to achieve an enhancement of the thermal stability in TL readings. Six types of samples are prepared with different dopant concentrations in the following ranges; Mg (0-0.20 mol%), Cu (0-0.05 mol%), Na and Si (0-0.9 mol%). The spectra measurements are carried out for the six types of samples using a TL emission spectra measurement device. The spectra measurement device consists of a monochromator, photomultiplier tube and temperature control unit to thermally stimulate the samples. The measured data shows the light emission during heating of the sample as a function of temperature and wavelength (three-dimensional TL spectra). The spectra were analysed using a method of deconvolution based on gaussian curve. The wavelength of a main peak of the emission spectra changes depending on the existence of the Cu dopant, while intensity of the spectra rapidly changes with the Cu dopant concentrations. The 385 nm emission is mainly observed in all the spectra from the samples with the Cu dopant, but in those from the samples without the Cu dopant a very weak 401 nm emission is mainly observed. However, any change in the wavelength at a main peak of the TL emission spectra from the sample materials with Na and Si dopants is not observed but that in the intensity at a peak of the spectra is observed.

Combinatorial Chemistry Techniques↗
PubMed2006

Highly polarization-dependent periodic coupling in mechanically induced long period grating over air-silica fibers.

A very flexible and versatile tunable mechanical grating platform is introduced, with which highly polarization-dependent mode coupling is observed for three types of air-silica microstructured fibers: hollow core fiber, hexagonal-boundary holey fiber (HHF), and circular-boundary holey fiber. The resonances of gratings showed highly polarization-dependent broadband coupling compared with conventional single-mode fibers due to their unique beat-length dispersions between the core and the cladding modes, which could find applications in wideband polarization-dependent loss compensation. We further present significance of the spatial symmetry of HHF in distinct mode coupling for different rotation angles around the fiber axis.

Journal Article↗
PubMed2006

The StarClose Vascular Closure System: interventional results from the CLIP study.

BACKGROUND: The StarClose Vascular Closure System is a femoral access site closure technology that uses a flexible nitinol clip to complete a circumferential, extravascular arteriotomy close. The Clip CLosure In Percutaneous Procedures study was initiated to study the safety and efficacy of the StarClose device in subjects undergoing diagnostic and interventional catheterization procedures. METHODS: A total of 17 U.S. sites enrolled 596 subjects, with 483 subjects randomized at a 2:1 ratio to receive StarClose or standard compression of the arteriotomy after the percutaneous procedure. The study included roll-in (n = 113), diagnostic (n = 208), and interventional (n = 275) arms with a primary safety endpoint of major vascular complications through 30 days and a primary efficacy endpoint of postprocedure time to hemostasis. RESULTS: The results of the diagnostic StarClose cohort have been reported separately. Results for the interventional arm revealed major vascular complications occurring in 1.1% of StarClose subjects (2/184) and 1.1% in manual compression subjects (1/91; P = 1.00). No infections were seen in either cohort. Minor complications in the StarClose interventional group occurred at a rate of 4.3% (8/184) and with compression at 9.9% (9/91; P = 0.107). Pseudoaneurysm or arteriovenous fistula was not seen with StarClose. With StarClose, procedural success was 100% (136/136) for the diagnostic group and 98.9% (181/183) in the interventional group. Device success for the treatment group was 86.8%. In the interventional cohort, 87.3% (158/181) of StarClose subjects reported a pain scale of 0-3 compared with 93.3% (84/90) in the compression group, which was not statistically different. CONCLUSIONS: The clinical results of this study demonstrate that the StarClose Vascular Closure System is noninferior to manual compression with respect to the primary safety endpoint of major vascular events in subjects who undergo percutaneous interventional procedures. StarClose significantly reduced time to hemostasis, ambulation, and dischargeability when compared with compression.

Aged↗
PubMed2006

Physiological modelling of agitation-sedation dynamics.

Agitation-sedation cycling in critically ill patients, characterized by oscillations between states of agitation and over-sedation, damages patient health and increases length of stay and cost. A model that captures the essential dynamics of the agitation-sedation system and is physiologically representative is developed, and validated using data from 37 critical care patients. It is more physiologically representative than a previously published agitation-sedation model, and captures more realistic and complex dynamics. The median time in the 90% probability band is 90%, and the total drug dose, relative to recorded drug dose data, is a near ideal 101%. These statistical model validation metrics are 5-13% better than a previously validated model. Hence, this research provides a platform to develop and test semi-automated sedation management controllers that offer the significant clinical potential of improved agitation management and reduced length of stay in critical care.

Procedural Sedation↗
PubMed2006

Molecular characterization of the porcine endogenous retrovirus subclass A and B envelope gene from pigs.

Xenotransplantation of porcine organs has the potential to overcome the current critical shortage of allogenic organs for transplantation in humans. However, the existence of porcine endogenous retroviruses (PERVs) presents a problem for the clinical use of xenografts from pigs. In an attempt to understand the molecular characteristics of PERVs, we cloned the PERV env gene from six pig breeds (ie, Berkshire, Duroc, Landrace, Yorkshire, and two types of miniature pigs) in Korea. A total of 141 env clones were isolated and their sequences were analyzed. Phylogenetic analyses of these genes revealed the presence of PERVs, from both classes A and B, in 54% and 46% of the env clones, respectively. Among these clones, 37 isolates had the correct open reading frame (ORF; 27 clones in subclass A and 10 clones in subclass B), while the others had premature termination. These PERV nucleotide sequences can be used in a database for comparisons of PERV distribution among different pig breeds and for monitoring PERV infection using isolates with functional ORFs. Recombinant envelope of subclass A and B with functional ORF was expressed by vaccinia virus systems. Additionally isolated env clones can be used for various experiments, such as PERV control and infectivity tests, and may enhance the understanding of molecular mechanisms through pseudotyped PERV viruses.

Animals↗
PubMed2006

SNP-based markers for discriminating olive (Olea europaea L.) cultivars.

A set of 11 polymorphic markers (1 cleaved amplified polymorphic sequence (CAPS), 2 sequence-characterized amplified regions (SCARs), and 8 single-nucleotide polymorphism (SNP)-derived markers) was obtained for olive cultivar identification by comparing DNA sequences from different accessions. Marker development was more efficient, using sequences from the database rather than cloning arbitrary DNA fragments. Analyses of the sequences of 3 genes from 11 diverse cultivars revealed an SNP frequency of 1 per 190 base pairs in exons and 1 per 149 base pairs in introns. Most mutations were silent or had little perceptible effect on the polypeptide encoded. The higher incidence of transversions (55%) suggests that methylation is not the major driving force for DNA base changes. Evidence of linkage disequilibrium in 2 pairs of markers has been detected. The set of predominantly SNP-based markers was used to genotype 65 olive samples obtained from Europe and Australia, and was able clearly to discriminate 77% of the cultivars. Samples, putatively of the same cultivar but derived from different sources, were revealed as identical, demonstrating the utility of these markers as tools for resolving nomenclature issues. Genotyping data were used for constructing a dendrogram by UPGMA cluster analysis using the simple matching similarity coefficient. Relationships between cultivars are discussed in relation to the route of olive's spread.

Base Sequence↗
PubMed2006

Synchronous bifocal alveolar rhabdomyosarcoma: a case report.

We report a case of bifocal rhabdomyosarcoma involving the hand and thigh in an 11-year-old female. We highlight the importance of a thorough clinical examination and an aggressive surgical approach in which each lesion is treated as a separate primary.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Physiological modelling of agitation-sedation dynamics including endogenous agitation reduction.

Sedation administration and agitation management are fundamental activities in any intensive care unit. A lack of objective measures of agitation and sedation, as well as poor understanding of the underlying dynamics, contribute to inefficient outcomes and expensive healthcare. Recent models of agitation-sedation pharmacodynamics have enhanced understanding of the underlying dynamics and enable development of advanced protocols for semi-automated sedation administration. However, these initial models do not capture all observed dynamics, particularly periods of low sedative infusion. A physiologically representative model that incorporates endogenous agitation reduction (EAR) dynamics is presented and validated using data from 37 critical care patients. High median relative average normalised density (RAND) values of 0.77 and 0.78 support and minimum RAND values of 0.51 and 0.55 for models without and with EAR dynamics respectively show that both models are valid representations of the fundamental agitation-sedation dynamics present in a broad spectrum of intensive care unit (ICU) patients. While the addition of the EAR dynamic increases the ability of the model to capture the observed dynamics of the agitation-sedation system, the improvement is relatively small and the sensitivity of the model to the EAR dynamic is low. Although this may represent a limitation of the model, the inclusion of EAR is shown to be important for accurately capturing periods of low, or no, sedative infusion, such as during weaning prior to extubation.

Biomedical Engineering↗
PubMed2005

Size-resolved kinetic measurements of aluminum nanoparticle oxidation with single particle mass spectrometry.

Aluminum nanoparticles are being considered as a possible fuel in advanced energetic materials application. Of considerable interest therefore is a knowledge of just how reactive these materials are, and what the effect of size on reactivity is. In this paper we describe results of size resolved oxidation rate using a recently developed quantitative single particle mass spectrometer (SPMS). Aluminum nanoparticles used were either generated by DC Arc discharge or laser ablation, or by use of commercial aluminum nanopowders. These particles were oxidized in an aerosol flow reactor in air for specified various temperatures (25-1100 degrees C), and subsequently sampled by the SPMS. The mass spectra obtained were used to quantitatively determine the elemental composition of individual particles and their size. We found that the reactivity of aluminum nanoparticles is enhanced with decreasing primary particle size. Aluminum nanoparticles produced from the DC Arc, which produced the smallest primary particle size (approximately 19 nm), were found to be the most reactive (approximately 68% aluminum nanoparticles completely oxidized to aluminum oxide at 900 degrees C). In contrast, nanopowders with primary particle size greater than approximately 50 nm were not fully oxidized even at 1100 degrees C (approximately 4%). The absolute rates observed were found to be consistent with an oxide diffusion controlled rate-limiting step. We also determined the size-dependent diffusion-limited rate constants and Arrehenius parameters (activation energy and pre-exponential factor). We found that as the particle size decreases, the rate constant increases and the activation energy decreases. This work provides a quantification of the known pyrophoric nature of fine metal particles.

Journal Article↗
PubMed2005

Sentinel node biopsy can replace four-node-sampling in staging early breast cancer.

AIM: Four-node axillary sampling for breast cancer is an established method of staging the axilla in the United Kingdom. We report the sensitivity of sentinel node (SN) biopsy and compare it with that of four-node sampling. METHODS: SN identification was attempted in 234 consecutive patients with unifocal breast cancers up to 25 mm in diameter on pre-operative ultrasound. A combination of isotope-labelled nanocolloid and patent blue dye techniques were used and SN were identified in 221 (94.5%). All patients underwent back-up four-node sampling and those with positive sentinel nodes on frozen section (FS) underwent immediate full axillary clearance. RESULTS: Among those patients who had SN successfully identified, an average of 1.38 SN were identified per patient. Histological examination of the SN alone would have identified all node-positive patients that the four-node sample identified. CONCLUSION: In patients who have SN identified, four-node axillary sampling does not provide any additional information.

Axilla↗
PubMed2005

Spontaneous chronic spinal subdural hematoma associated with spinal arachnoiditis and syringomyelia.

Spontaneous chronic spinal subdural hematoma is rare. We describe a case of spontaneous chronic spinal subdural hematoma associated with arachnoiditis and syringomyelia in a 76-year old woman who presented with a 14-year history of progressive myelopathy. MRI scan revealed a thoraco-lumbar subdural cystic lesion and a thoracic syrinx. The patient underwent thoracic laminectomy and decompression of the lesion, which was a subdural hematoma. A myelotomy was performed to drain the syrinx. Pathological examination revealed features consistent with chronic subdural membrane. This report attempts to elucidate the pathogenesis of chronic spinal subdural hematoma. We discuss possible etiological factors in light of the current literature and pathogenesis of both spinal subdural hematoma and syrinx formation.

Aged↗
PubMed2005

Fluid flow structure in arterial bypass anastomosis.

The fluid flow through a stenosed artery and its bypass graft in an anastomosis can substantially influence the outcome of bypass surgery. To help improve our understanding of this and related issues, the steady Navier-Stokes flows are computed in an idealized arterial bypass system with partially occluded host artery. Both the residual flow issued from the stenosis--which is potentially important at an earlier stage after grafting--and the complex flow structure induced by the bypass graft are investigated. Seven geometric models, including symmetric and asymmetric stenoses in the host artery, and two major aspects of the bypass system, namely, the effects of area reduction and stenosis asymmetry, are considered. By analyzing the flow characteristics in these configurations, it is found that (1) substantial area reduction leads to flow recirculation in both upstream and downstream of the stenosis and in the host artery near the toe, while diminishes the recirculation zone in the bypass graft near the bifurcation junction, (2) the asymmetry and position of the stenosis can affect the location and size of these recirculation zones, and (3) the curvature of the bypass graft can modify the fluid flow structure in the entire bypass system.

Animals↗
PubMed2005

Symptoms of non-gonococcal urethritis in heterosexual men: a case control study.

OBJECTIVE: To determine microbial and behavioural factors contributing to non-gonococcal urethral symptoms in men. METHODS: Case-control study of heterosexual men with non-gonococcal urethral symptoms (cases) and without urethral symptoms (controls) attending Melbourne Sexual Health Centre, Australia. Sexual behaviour and condom use were measured by questionnaire. First stream urine was tested for potential pathogens: Chlamydia trachomatis (ligase chain reaction), Mycoplasma genitalium (polymerase chain reaction, PCR), Ureaplasma urealyticum (culture and PCR), and Streptococcus spp, Gardnerella vaginalis, and Haemophilus species (culture). Urethral smears from cases were examined for polymorphonuclear leucocytes. RESULTS: 80 cases and 79 controls were recruited over 4 months in 2002-3. 49 cases (61%) had urethritis by microscopic criteria, 17 (21%) had Chlamydia trachomatis (adjusted odds ratio (OR) 27 (95% confidence interval (CI): 3.4 to 222)), five (6%) had Mycoplasma genitalium (OR 6.1 (95% CI: 0.6 to 61)), and 11 (14%) had Gardnerella vaginalis (OR 9.0 (95% CI: 1.6 to 52)). Other organisms were not significantly associated with urethral symptoms. The presence of urethritis on urethral smear did not predict the presence of Chlamydia trachomatis (OR 1.7 (95% CI: 0.5 to 5.4)). Urethral symptoms were significantly associated with unprotected vaginal sex with more than one casual partner (OR 9.3 (95% CI: 1.3 to 65)) and unprotected anal sex with a regular partner in the past month (OR 3.5 (95% CI: 1.0 to 13)). CONCLUSION: Gardnerella vaginalis and unprotected anal sex may cause symptoms of non-gonococcal urethritis. Microscopy of the urethral smear to diagnose urethritis in this population does not help to identify which men with urethral symptoms require treatment for chlamydia.

Adult↗
PubMed2004

Genotyping single nucleotide polymorphisms in barley by tetra-primer ARMS-PCR.

Single nucleotide polymorphisms (SNPs) are the most abundant form of DNA polymorphism. These polymorphisms can be used in plants as simple genetic markers for many breeding applications, for population studies, and for germplasm fingerprinting. The great increase in the available DNA sequences in the databases has made it possible to identify SNPs by "database mining", and the single most important factor preventing their widespread use appears to be the genotyping cost. Many genotyping platforms rely on the use of sophisticated, automated equipment coupled to costly chemistry and detection systems. A simple and economical method involving a single PCR is reported here for barley SNP genotyping. Using the tetra-primer ARMS-PCR procedure, we have been able to assay unambiguously five SNPs in a set of 132 varieties of cultivated barley. The results show the reliability of this technique and its potential for use in low- to moderate-throughput situations; the association of agronomically important traits is discussed.

Alleles↗
PubMed2004

Safety, tolerability and pharmacokinetics of subcutaneous A6, an 8-amino acid peptide with anti-angiogenic properties, in healthy men.

AIMS: To assess the safety, tolerability and pharmacokinetics of subcutaneous A6, an 8-amino acid peptide with anti-angiogenic properties, in healthy men. METHODS: Double-blind, placebo-controlled, parallel-group, dose-rising, phase I study of single and repeated doses. In the single dose phase, successive groups of 5 subjects received A6 15, 35, 75, 150, 300 mg, or placebo, as subcutaneous injections in the upper thigh. In the repeat dose phase, 2 groups of 6 subjects received repeat doses of A6 35 mg and 75 mg, or placebo, and 1 group of 5 subjects received 150 mg, or placebo, 12-hourly for 6 days (11 doses in total). In each group, 4 subjects received active treatment, the remainder placebo. Pharmacokinetics of A6 were assessed up to 24 h after single doses, for 12 h after the first of the repeated doses, and up to 24 h after the last of the repeated doses. MATERIALS: A6 for subcutaneous injection in phosphate buffer, pH 5.6-6.0. Phosphate-buffered saline was used as placebo. RESULTS: All dose regimens of A6 were safe and well-tolerated, both systemically and locally. Time to peak plasma concentration was similar (0.5-2.1 h) in all dosage groups. Cmax and AUC(0-inf) were linearly proportional to dose. Mean Cmax ranged from 454-10,333 ng/ml and mean AUC(0-inf) from 1,690-43,371 ng x h/ml after the 15 and 300 mg single doses, respectively. Terminal t(1/2) was 1.4-1.8 h, and there was no evidence of unexpected drug accumulation. Urinary excretion of unchanged A6 was 94.6% (SD 20.7) after the 300 mg single dose (0-24 h collection), and 78.4% (SD 13.0) after the 150 mg repeated dose (0-12 h collection). A6 did not trigger production of anti-A6 IgG antibodies within 14 days of the first dose. CONCLUSION: Single doses of A6 up to 300 mg, and repeated doses up to 150 mg, were well-tolerated and safe in healthy young men. A6 was rapidly absorbed; it was eliminated, mainly unchanged, in urine. Plasma concentrations were dose-proportional. A6 did not trigger an early immunogenic response.

Adolescent↗