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Biomedical subjects

D E Lee

Publications and source records attributed to D E Lee.

At least 19 recordsLinked to original sources
PubMed2003

Matrix formalism of electromagnetic wave propagation through multiple layers in the near-field region: application to the flat panel display.

We have developed an electromagnetic (EM) wave propagation theory through a single layer and multiple layers in the near-field and far-field regions, and have constructed a matrix formalism in terms of the boundary conditions of the EM waves. From the shielding efficiency (SE) against EM radiation in the near-field region calculated by using the matrix formalism, we propose that the effect of multiple layers yields enhanced shielding capability compared to a single layer with the same total thickness in conducting layers as the multiple layers. We compare the intensities of an EM wave propagating through glass coated with conducting indium tin oxide (ITO) on one side and on both sides, applying it to the electromagnetic interference (EMI) shielding filter in a flat panel display such as a plasma display panel (PDP). From the measured intensities of EMI noise generated by a PDP loaded with ITO coated glass samples, the two-side coated glass shows a lower intensity of EMI noise compared to the one-side coated glass. The result confirms the enhancement of the SE due to the effect of multiple layers, as expected in the matrix formalism of EM wave propagation in the near-field region. In the far-field region, the two-side coated glass with ITO in multiple layers has a higher SE than the one-side coated glass with ITO, when the total thickness of ITO in both cases is the same.

Journal Article↗
PubMed2001

Molecular cloning and cultivar specific expression of MAP kinases from Capsicum annuum.

Two MAP kinases, MK1 and MK2, were cloned from Capsicum annuum (pepper) cv. Subicho using a parsley MAP kinase gene as a heterologous probe. MK1 and MK2 encode stress-inducible protein kinases that can contribute to the response to wounding, UV-C, and cold. MK1 has a 92% amino acid identity with WIPK of tobacco. It was transcriptionally induced in response to wounding. In contrast, no detectable MK1 transcript was found in unwounded leaves of pepper. MK2 has a high level of amino acid homology to MAP kinases, such as NTF4 and SIPK and was constitutively expressed in all tissues. Both MK transcripts were downregulated by UV-C treatment. Each MK protein activation was independently wound-inducible in a cultivar dependent manner. MK1 is phosphorylated in cv. Pungchon but not cv. Subicho; whereas, the MK2 protein activation by wounding is restricted to cv. Subicho. In addition, de novo synthesis of the MK1 protein and tyrosine phosphorylation was rapidly and transiently induced in cv. Pungchon by wounding. In contrast, it is highly unlikely that the MK1 protein is produced in cv. Subicho, even though there is an abundant expression of MK1 mRNA after wounding in this cultivar. In Escherichia coli, which overexpresses MK1, autophosphorylation is observed at conserved threonine and tyrosine phosphorylation sites.

Amino Acid Sequence↗
PubMed2001

High-level expression and one-step purification of cyclic amidohydrolase family enzymes.

The cyclic amidohydrolase family enzymes, including hydantoinase, dihydropyrimidinase, allantoinase and dihydroorotase, are metal-dependent hydrolases and play a crucial role in the metabolism of purine and pyrimidine in prokaryotic and eukaryotic cells. With the increasing demand for the elucidation of enzyme structures and functions, along with industrial applications, the research on the family enzymes has recently been proliferating, but the related enzymes had been purified conventionally by multistep purification procedures. Here, we reported the expression in Escherichia coli cells of maltose-binding protein-fused family enzymes and their one-step purification. The expression levels of the fusion proteins account for 20-35% of the total protein in E. coli, allowing approximately 2-3 mg of the purified proteins by affinity chromatography to be obtained per 0.3 L of bacterial culture. As more promising results, their nascent biochemical properties, after the cleavage of the fusion proteins with Factor Xa, in terms of oligomeric structure, optimal pH, specific activity, and kinetic property, were also conserved as those from the native enzymes. The availability of the family enzymes to fusion strategy shows potential as a convenient procedure to recombinant protein purification and accelerates the structure-function study of the related family enzymes.

ATP-Binding Cassette Transporters↗
PubMed2001

Sclerotherapy with use of doxycycline after percutaneous drainage of postoperative lymphoceles.

PURPOSE: To assess the use of doxycycline as a sclerosing agent after percutaneous drainage of postoperative lymphoceles. MATERIALS AND METHODS: Symptomatic postoperative lymphoceles (n = 21) in 18 patients were treated by percutaneous tube drainage for an average of 10.8 days. Sclerosis was performed when the patient became asymptomatic, drainage had slowed to less than 30 mL/d and follow-up imaging (CT or US) showed either near complete or total resolution of the lymphocele. Doxycycline (500 mg) combined with 1% lidocaine (5 mL) was instilled into the cavity with use of a syringe after any remaining lymphocele fluid was removed through the tube. When possible, patients were instructed to perform a series of maneuvers for the next hour to distribute the sclerosing agent evenly throughout the cavity. After 1 hour, the sclerosing agent was aspirated from the cavity and the drainage tube was removed. Three patients with four lymphoceles underwent sclerotherapy immediately after percutaneous insertion of a drainage tube and aspiration of the lymphocele. No patients underwent previous sclerosis with any agent. RESULTS: Successful treatment of postoperative lymphoceles was achieved in 17 of 18 patients. Primary success was achieved in 17 of 21 lymphoceles treated. There were four lymphocele recurrences in three patients. Three of the four recurrences were successfully treated by means of repeated drainage and sclerotherapy. One recurrent lymphocele persisted after re-treatment with 1 g of doxycycline. This patient underwent successful surgical repair. There were no complications related to doxycycline sclerosis. The mean duration of drainage for initial and recurrent lymphoceles was 10.8 days (range, 0-30 days). CONCLUSION: Sclerotherapy with use of doxycycline after percutaneous drainage is an easy, safe, inexpensive, and effective means of treating postoperative lymphoceles.

Aged↗
PubMed2000

Direct graft puncture with use of a crossed catheter technique for thrombolysis of peripheral bypass grafts.

PURPOSE: To determine the efficacy and safety of direct graft puncture of peripheral arterial bypass grafts with placement of retrograde and antegrade catheters within the graft for thrombolytic therapy. This study also evaluated potential clinical benefit to patients. MATERIALS AND METHODS: A retrospective study was performed on 19 patients with 24 peripheral bypass grafts and lower extremity ischemia of less than 1 month duration. Thrombolysis was performed with a continuous high-dose infusion of urokinase. Successful lysis was defined as greater than 95% clot dissolution with antegrade flow within the graft. RESULTS: Technical success was achieved in 17 of 19 patients (89%). The complexity of operative intervention was diminished in 12 of 19 patients (63%). The major complication rate (16%) was significantly higher and, therefore, this technique has a role for patients in whom traditional access is not optimal, such as in those in whom access cannot be achieved or in those with long bypass grafts. CONCLUSION: Direct graft puncture with placement of catheters across the proximal and distal anastomoses of bypass grafts is a safe method of access, with a major complication rate similar to conventional access techniques. This mode of graft access demonstrates efficacious thrombolysis and acts as a conduit for ancillary procedures.

Aged↗
PubMed2000

Construction and evaluation of a novel bifunctional N-carbamylase-D-hydantoinase fusion enzyme.

A fully enzymatic process employing two sequential enzymes, D-hydantoinase and N-carbamylase, is a typical case requiring combined enzyme activity for the production of D-amino acids. To test the possibility of generating a bifunctional fusion enzyme, we constructed a fusion protein via end-to-end fusion of a whole gene that encodes an intact protein at the N terminus of the D-hydantoinase. Firstly, maltose-binding protein (MBP) gene of E. coli was fused with D-hydantoinase gene from Bacillus stearothermophilus SD1, and the properties of the resulting fusion protein (MBP-HYD) were compared with those of native D-hydantoinase. Gel filtration and kinetic analyses clearly demonstrated that the typical characteristics of D-hydantoinase are maintained even in a fusion state. Based on this result, we constructed an artificial fusion enzyme composed of the whole length of N-carbamylase (304 amino acids [aa]) from Agrobacterim radiobacter NRRL B11291 and D-hydantoinase (471 aa). The fusion enzyme (CAB-HYD) was functionally expressed with an expected molecular mass of 86 kDa and efficiently converted exogenous hydantoin derivatives to the D-amino acids. A related D-hydantoinase (HYD1) gene from Bacillus thermocatenulatus GH2 was also fused with the N-carbamylase gene at its N terminus. The resulting enzyme (CAB-HYD1) was bifunctional as expected and showed better performance than the CAB-HYD fusion enzyme. The conversion of hydantoin derivatives to corresponding amino acids by the fusion enzymes was much higher than that by the separately expressed enzymes, and comparable to that by the coexpressed enzymes. Thus, the fusion enzyme might be useful as a potential biocatalyst for the production of nonnatural amino acids.

ATP-Binding Cassette Transporters↗
PubMed2000

Functional expression and characterization of the two cyclic amidohydrolase enzymes, allantoinase and a novel phenylhydantoinase, from Escherichia coli.

A superfamily of cyclic amidohydrolases, including dihydropyrimidinase, allantoinase, hydantoinase, and dihydroorotase, all of which are involved in the metabolism of purine and pyrimidine rings, was recently proposed based on the rigidly conserved structural domains in identical positions of the related enzymes. With these conserved domains, two putative cyclic amidohydrolase genes from Escherichia coli, flanked by related genes, were identified and characterized. From the genome sequence of E. coli, the allB gene and a putative open reading frame, tentatively designated as a hyuA (for hydantoin-utilizing enzyme) gene, were predicted to express hydrolases. In contrast to allB, high-level expression of hyuA in E. coli of a single protein was unsuccessful even under various induction conditions. We expressed HyuA as a maltose binding protein fusion protein and AllB in its native form and then purified each of them by conventional procedures. allB was found to encode a tetrameric allantoinase (453 amino acids) which specifically hydrolyzes the purine metabolite allantoin to allantoic acid. Another open reading frame, hyuA, located near 64.4 min on the physical map and known as a UUG start, coded for D-stereospecific phenylhydantoinase (465 amino acids) which is a homotetramer. As a novel enzyme belonging to a cyclic amidohydrolase superfamily, E. coli phenylhydantoinase exhibited a distinct activity toward the hydantoin derivative with an aromatic side chain at the 5' position but did not readily hydrolyze the simple cyclic ureides. The deduced amino acid sequence of the novel phenylhydantoinase shared a significant homology (>45%) with those of allantoinase and dihydropyrimidinase, but its functional role still remains to be elucidated. Despite the unclear physiological function of HyuA, its presence, along with the allantoin-utilizing AllB, strongly suggested that the cyclic ureides might be utilized as nutrient sources in E. coli.

Amidohydrolases↗
PubMed1999

Comparison of behavioral responses to noxious cold and heat in mice.

We investigated behavioral responses to noxious cold and heat stimuli in mice. Similar to the hot-plate test, mice showed licking or jumping responses on a cold-plate (0 degrees C). The sensitivity to noxious heat (55 degrees C) was not correlated to the sensitivity to noxious cold, indicating that nociceptive processing of cold and heat are different. Behavioral responses to noxious cold are inhibited by systemic morphine or intrathecal administration of morphine. Lesion of the medial frontal cortex, including the anterior cingulate cortex, or selective activation of two types of opioid receptors in the anterior cingulate cortex produces dose-dependent antinociceptive effects on behavioral responses to noxious cold stimuli. These results suggest that activation of opioid receptors in the anterior cingulate cortex can produce powerful antinociception.

Analgesics, Opioid↗
PubMed1999

Receptor activator of NF-kappaB recruits multiple TRAF family adaptors and activates c-Jun N-terminal kinase.

Receptor activator of NF-kappaB (RANK) is a recently cloned member of the tumor necrosis factor receptor (TNFR) superfamily, and its function has been implicated in osteoclast differentiation and dendritic cell survival. Many of the TNFR family receptors recruit various members of the TNF receptor-associated factor (TRAF) family for transduction of their signals to NF-kappaB and c-Jun N-terminal kinase. In this study, the involvement of TRAF family members and the activation of the JNK pathway in signal transduction by RANK were investigated. TRAF1, 2, 3, 5, and 6 were found to bind RANK in vitro. Association of RANK with each of these TRAF proteins was also detected in vivo. Expression of RANK in cultured cells also induced the activation of JNK, which was blocked by a dominant-negative form of JNK. Furthermore, by employing various C-terminal deletion mutants of RANK, the regions responsible for TRAF interaction and JNK activation were identified. TRAF5 was determined to bind to the C-terminal 11 amino acids and the other TRAF members to a region N-terminal to the TRAF5 binding site. The domain responsible for JNK activation was localized to the same region where TRAF1, 2, 3, and 6 bound, which suggests that these TRAF molecules might mediate the RANK-induced JNK activation.

Amino Acid Sequence↗
PubMed1998

Use of intraoperative ultrasonography during hepatic transplantation.

The aim of this study was to evaluate if intraoperative vascular ultrasonography is of clinical value in the perioperative management of hepatic transplant patients. Fifteen intraoperative ultrasonographic examinations were performed on 13 patients (five female, eight male) during transplantation. These patients had clinically suspected vascular compromise. Among the 13 patients studied intraoperatively, five were correctly diagnosed as having hemodynamically significant vascular compromise. Of the intraoperative vascular sonographic examinations, the results of 13 were in concordance with the surgical impression as to whether further intervention was necessary or if the procedure could be terminated. Intraoperative sonography demonstrates potential to be of aid to the surgeon in recognition of vascular compromise.

Adult↗
PubMed1995

ICG-enhanced digital angiography and photocoagulation of choroidal neovascularization in age-related macular degeneration.

Choroidal neovascular membranes are often poorly defined on fluorescein angiography because of fluorescein leakage or blockage of hyperfluorescence by overlying hemorrhage, lipid, turbid fluid, or pigment. Indocyanine green (ICG) is a highly protein-bound dye in the near infrared portion of the spectrum. Therefore, ICG remained in and around the neovascular membrane and enhanced the visualization of certain membranes poorly defined with fluorescein. ICG penetrated through the overlying turbid tissue, and improved the visualization of the underlying choroidal neovascular membrane. Using an infrared angiography system, the authors obtained 21 ICG-angiograms with suspected choroidal neovascularization, and compared them to fluorescein angiograms. In 5 of the 21 eyes, occult choroidal neovascularization was well delineated on the ICG angiograms. In 2 eyes, we were able to detect a well-defined choroidal neovascular membrane underlying a subretinal hemorrhage. In 12 of the 21 eyes with choroidal neovascular membrane, we performed argon-green laser photocoagulation applying the overlay technique of the ICG angiogram to red-free photo or the early fluorescein angiogram, and evaluated the effect of full coverage laser treatment.

Choroid↗
PubMed1991

Effects of hyperlipemia on radioimmunoassays for progesterone, testosterone, thyroxine, and cortisol in serum and plasma samples from dogs.

Hyperlipemic serum and plasma samples often are received by clinical laboratories for endocrinologic analysis by radioimmunoassay. We designed a study to determine what effect, if any, hyperlipemia has on estimation of lipid-soluble hormone concentrations determined by solid-phase radioimmunoassays. Progesterone, testosterone, thyroxine, and cortisol concentrations were determined in canine plasma and serum with various degrees of lipemia. Samples of serum, heparinized plasma, and EDTA-treated plasma were obtained from blood collected from 4 female and 4 male Beagles by use of evacuated tubes. To induce hyperlipemia in vitro, IV fat emulsion was diluted in deionized water to produce 0 (water only), 33, 67, or 100% mixtures. Twenty microliters of each mixture then was added to the subsamples of serum and plasma from each dog. Hormone concentrations were determined, using validated radioimmunoassays. Triglyceride concentrations were determined by enzymatic assay. Addition of IV fat emulsion in vitro was an accurate and reproducible means of altering triglyceride concentrations in the samples. Triglyceride concentrations as high as 700 mg/dl had no effect on radioimmunoassays for progesterone, testosterone, and thyroxine in serum, heparinized plasma, or EDTA-treated plasma. Addition of 100% (but not 33 or 67%) fat emulsion reduced the mean cortisol concentration in heparinized plasma by 12% (P less than 0.05). This severe hyperlipemia did not affect quantification of cortisol in serum or EDTA-treated plasma.

Animals↗
PubMed1991

Using data describing physician inpatient practice patterns: issues and opportunities.

Information on physicians' inpatient practice patterns is becoming increasingly available through state data systems. This article describes the kind of information that is becoming publicly available, provides illustrations of how these data can be used, and discusses issues and potential problems that may occur in using the data.

Health Services Research↗
PubMed1990

Public information on private practice: the availability of physician inpatient data.

Despite increased interest in information describing physicians and their hospitalized patients, little attention has been given to the availability of these data and the related policy issues. We surveyed the 20 states with a publicly mandated data system based on hospital discharge abstracts that included physician information. States vary considerably in their orientation toward the public availability of the information and in the ability to personally identify physicians from the data. Potential benefits and problems in using the information for health services research, in improving the quality of care, and in analyzing practice patterns are reviewed. The policy issues associated with the collection and use of publicly available data on physicians and their hospitalized patients are discussed.

Confidentiality↗
PubMed1989

Nonconstrained total elbow arthroplasty. Development and results in patients with functional class IV rheumatoid arthritis.

Twenty-four nonconstrained total elbow arthroplasties (TEAs) in 20 patients with severe disabling functional class IV rheumatoid arthritis were reviewed retrospectively to determine the effects of their disease on the end result. The mean follow-up period was 6 years (range, 2-11 years). All planes of elbow motion improved after surgery (P less than .005), there was a highly significant reduction in pain and improvement in function (both P less than .005) and patient satisfaction was high. The severity of the disease does not appear to affect the end result when a nonconstrained TEA is used, and the results compare favorably with those of other series reported.

Adult↗
PubMed1988

Research note: reference others and self-destruction.

48 students were presented hypothetical situations having to do with smoking, drinking liquor, using other drugs, and over-eating. They were asked to indicate their reference others and the others' expectations for their behavior in these situations. Family members and friends were the most frequently named reference others, varying in importance with the situation. Perception of reference others' expectations tends to correspond with respondents' behavior, encouraging drinking and discouraging smoking and drugs. Inconsistencies between reference-others' expectations and respondents' behaviors and respondents' values elicited comments suggesting that the questions alone may lead respondents to feel dissatisfied with the behavior.

Adult↗