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Biomedical subjects

J Lee

Publications and source records attributed to J Lee.

At least 775 records · Page 43Linked to original sources
PubMed1998

Synthesis and biological activity of 5-hydroxy-4-quinolones and 5-methoxy-4-quinolones as truncated acridones.

A series of 5-hydroxy-4-quinolone (3) and 5-methoxy-4-quinolone (4) derivatives were synthesized as truncated acridone analogues and evaluated for antitumor, antiherpes and antituberculosis activities. Among them 5-hydroxy-8-methoxy-quinolone showed potent antitumor activity (IC50 = 17.7 microM for HL60) which was greater than that of acronycine. However, these compounds didn't show any significant antiherpes or antituberculosis activity.

Acridines↗
PubMed1998

Design and synthesis of bioisosteres of ultrapotent protein kinase C (PKC) ligand, 5-acetoxymethyl-5-hydroxymethyl-3-alkylidene tetrahydro-2-furanone.

Three compounds, 5-(acetoxymethyl)-5-(hydroxymethyl)-3-tetradecyl-2,5-dihydro-2-furanone (3), 5-(acetoxymethyl)-5-(hydroxymethyl)-3,3-dihexyltetrahydro-2-furano ne (4) and 5-(acetoxymethyl)-5-(hydroxymethyl)-3,3-dioctyltetrahydro-2-furano ne (5), were designed and synthesized as surrogates of the ultrapotent DAG analogue, 5-(acetoxymethyl)-5-(hydroxymethyl) 3-[(Z)-tetradecylidene]tetrahydro-2-furanone (1), a compound that showed high affinity for PKC-alpha (Ki = 35 nM) in a competition binding assay with [3H-20]phorbol-12,13-dibutyrate (PDBU). In an attempt to overcome the problem of generating geometrical E- and Z-isomers, as encountered with 1, the double bond was moved to an endocyclic location as in 3, or an additional alkyl chain was appended to C3 to give the corresponding 3,3-dialkyl saturated lactones (4 and 5). The lactone was constructed from glycidyl-4-methoxyphenyl ether in 5 steps. The target compounds showed reduced binding affinities for PKC-alpha with Ki values of 192 nM (3), 4,829 nM (4), and 2,812 nM (5), respectively. These results indicate that constrained DAG analogues having a tetrahydro-2-furanone template are effectively discriminated by PKC-alpha in terms of the direction of the long alkyl chain connected to the 3-position.

4-Butyrolactone↗
PubMed1998

Propofol enhances red cell antioxidant capacity in swine and humans.

PURPOSE: To determine the effect of an anaesthetic with antioxidant potential, propofol, on red blood cell (RBC) antioxidant enzyme activities and RBC susceptibility to peroxidative challenge. METHODS: Propofol was administered by intravenous bolus (2.5 mg.kg-1) and continuous infusion (36 and 72 ml.hr-1 in nine swine; 216 ml.hr-1 in two swine), to achieve serum concentrations between 5 and 30 micrograms.ml-1 for two hours at each rate. Arterial blood sampling was at 0, 10, 30, 60, and 120 min for each rate of infusion, for measurement of plasma propofol concentration, activities of plasma and RBC superoxide dismutase, glutathione peroxidase, glutathione reductase, RBC catalase, and RBC malondialdehyde (MDA) formation in response to ex vivo oxidative challenge with t-butyl hydrogen peroxide (tBHP; 1.5 mM). Antioxidant mechanisms were determined by in vitro study of MDA formation, GSH depletion, and oxidation of haemoglobin to methaemoglobin in human erythrocytes exposed to propofol 0-75 microM. The antioxidant potential of propofol was compared with that of alpha-tocopherol utilising the reaction with 2,4,6-tripyridyl-s-triazine (TPTZ). RESULTS: Propofol had no effect on plasma or RBC antioxidant enzyme activities. It inhibited RBC MDA production over the range of 0-20 micrograms.ml-1 (y = -18.683x + 85.431; R2 = 0.8174). Effective propofol concentrations for 25% and 50% reductions in MDA levels were 7-12 and 12-20 micrograms.ml-1, respectively. Propofol has a similar effect on human erythrocytes in vitro (R2 = 0.98). CONCLUSION: Propofol antagonises the effects of forced peroxidation of red cells at anaesthetic and sub-anaesthetic concentrations in swine. Its actions include scavenging of oxygen derived free radicals in a tocopherol-like manner.

Anesthetics, General↗
PubMed1998

Inhibitory effect of lignans from the rhizomes of Coptis japonica var. dissecta on tumor necrosis factor-alpha production in lipopolysaccharide-stimulated RAW264.7 cells.

The inhibitory effect of 10 lignan constituents isolated from the rhizomes of Coptis japonica var. dissecta on tumor necrosis factor (TNF)-alpha production in lipopolysaccharide (LPS)-stimulated macrophage cell line (RAW264.7 cells) has been studied. Among them, pinoresinol, woorenoside-V and lariciresinol glycoside showed significant inhibitory activities in the range from 37% to 55% at the concentration of 25 micrograms/ml. The results are first report that the lignans isolated from Coptis japonica inhibit TNF-alpha production, and suggest that the lignan components may partly participate in antiinflammatory and antiallergic effect of Coptis japonica through the inhibition of TNF-alpha production.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

Growth-associated synthesis of recombinant human glucagon and human growth hormone in high-cell-density cultures of Escherichia coli.

Synthesis of two recombinant proteins (human glucagon and human growth hormone) was investigated in fed-batch cultures at high cell concentrations of recombinant Escherichia coli. The glucose-limited growth was achieved without accumulation of metabolic by-products and hence the cellular environment is presumed invariable during growth and recombinant protein synthesis. Via exponential feeding in the two-phase fed-batch operation, the specific cell growth rate was successfully controlled at the desired rates and the fed-batch mode employed is considered appropriate for examining the correlation between the specific growth rate and the efficiency of recombinant product formation in the recombinant E. coli strains. The two recombinant proteins were expressed as fusion proteins and the concentration in the culture broth was increased to 15 g fusion growth hormone 1(-1) and 7 g fusion glucagon 1(-1). The fusion growth hormone was initially expressed as soluble protein but seemed to be gradually aggregated into inclusion bodies as the expression level increased, whereas the synthesized fusion glucagon existed as a cytoplasmic soluble protein during the whole induction period. The stressful conditions of cultivation employed (i.e., high-cell-density cultivation at low growth rate) may induce the increased production of various host-derived chaperones and thereby enhance the folding efficiency of synthesized heterologous proteins. The synthesis of the recombinant fusion proteins was strongly growth-dependent and more efficient at a higher specific growth rate. The mechanism linking specific growth rate with recombinant protein productivity is likely to be related to the change in cellular ribosomal content.

Colony Count, Microbial↗
PubMed1998

Algicidal effect of peridinium bipes on microcystis aeruginosa

Peridinium bipes exerted an inhibitory effect on the growth of Microcystis aeruginosa. The algicidal action of water-soluble extract from P. bipes was studied. After treatment with P. bipes extract, the absorption spectrum of M. aeruginosa culture changed markedly, particularly in the ranges of 500 approximately 650 and 420 approximately 460 nm. An increase in absorption in this wavelength resulted from a leakage of phycobilines, both phycocyanin and allophycocyanin, from the treated cells. However, no leakage of chlorophyll was detected. The leakage of phycobilines was a short-term effect, detectable within 1 h of incubation. Both the plasmalemma and thylakoid membranes in M. aeruginosa cells were damaged and distorted in fine structure after treatment with P. bipes extract. It is assumed that algicide from P. bipes exerts its effect on the cell membranes, giving rise to changes in membrane permeability and a dissociation of phycobiline assemblages, but not of chlorophyll complex, on the thylakoid membranes. As a result, phycobilines were leaked out from the cells.

Journal Article↗
PubMed1998

Reversal of pulmonary arteriovenous malformation after diversion of anomalous hepatic drainage.

Pulmonary arteriovenous malformation can occur in up to 25% of patients after a classic Glenn shunt. Although unproven, exclusion of hepatic venous blood from the lungs has been proposed as a possible cause. We present a patient born with anomalous hepatic venous drainage into the left atrium with an intact atrial septum in whom pulmonary arteriovenous malformation developed in childhood. This was reversed after diversion of the hepatic venous drainage to the right atrium, supporting exclusion of hepatic venous flow as the cause of pulmonary arteriovenous malformation. The association with the hepatopulmonary syndrome is discussed.

Arteriovenous Malformations↗
PubMed1998

Genetic analysis of inflammatory bowel disease in a large European cohort supports linkage to chromosomes 12 and 16.

BACKGROUND & AIMS: Inflammatory bowel disease (IBD) is a complex disorder of unknown etiology. Epidemiological investigations suggest a genetic basis for IBD. Recent genetic studies have identified several IBD linkages. The significance of these linkages will be determined by studies in large patient collections. The aim of this study was to replicate IBD linkages on chromosomes 12 and 16 in a large European cohort. METHODS: Three hundred fifty-nine affected sibling pairs from 274 kindreds were genotyped using microsatellite markers spanning chromosomes 12 and 16. Affection status of the sibling pairs was defined as Crohn's disease (CD) or ulcerative colitis (UC). RESULTS: Nonparametric statistical analyses showed linkage for both chromosomes. Two-point results for chromosome 12 peaked at D12S303 (logarithm of odds [LOD], 2.15; P = 0.003) for CD and at D12S75 (LOD, 0.92; P = 0.03) for UC. Multipoint analyses produced a peak LOD of 1.8 for CD. Chromosome 16 showed linkage for CD at marker D16S415 (LOD, 1.52; P = 0.007). Multipoint support peaked above markers D16S409 and D16S411 (LOD, 1.7). CONCLUSIONS: These data are consistent with linkage of IBD to chromosomes 12 and 16. The replication of genetic risk loci in a large independent family collection indicates important and common susceptibility genes in these regions and will facilitate identification of genes involved in IBD.

Chromosomes, Human, Pair 12↗
PubMed1998

Treatment of spider veins with the 595 nm pulsed-dye laser.

BACKGROUND: Previous attempts to treat spider veins with the conventional 585 nm pulsed-dye laser with a 0.5-ms pulse duration have been relatively ineffective. Recently, a new pulsed-dye laser that is tunable from 585 to 600 nm with a pulse duration 3 times longer than previously available lasers has preliminarily been shown to be effective for treatment of spider veins. OBJECTIVE: Our purpose was to evaluate the effectiveness of multiple treatments with the tunable long-pulse dye laser in treatment of spider veins of the lower extremity. METHODS: Ten female volunteers were treated in two separate areas containing blue or red linear spider veins less than 1.5 mm in diameter. Treatments were administered with the pulsed-dye laser with a 1.5-ms pulse duration and 595-nm light at fluences of 15 and 20 J/cm2, and each subject received a total of 3 treatments at each site, administered at 6-week intervals. Photographs were taken before and 6 weeks after the last treatment. RESULTS: Computer-based image analysis showed clearing of more than three fourths of veins after 3 treatments with 15 or 20 J/cm2. Side effects were minimal and the treatments were well tolerated. CONCLUSION: The 595 nm, 1.5 ms pulse duration, pulsed-dye laser is safe and effective for treating blue or red spider veins of the lower extremities less than 1.5 mm in diameter in nontanned patients with Fitzpatrick skin types I and II. Multiple treatments improve on the results obtained after a single treatment.

Adult↗
PubMed1998

Inhibition of immediate type allergic reactions by the aqueous extract of Kum-Hwang-San.

We studied the effect of aqueous extract of Kum-Hwang-San (KHS) on mast cell-mediated immediate type allergic reactions. KHS (1-100 microg/site) inhibited concentration-dependently mast cell-dependent ear swelling response induced by compound 48/80 (200 microg/site) in mice by both topical and intradermal application. KHS (0.1-100 microg/site) inhibited concentration-dependently passive cutaneous anaphylaxis induced by anti-dinitrophenyl (DNP) IgE in rats by both topical and intradermal application. KHS also inhibited concentration-dependently the histamine release from the rat peritoneal mast cells (RPMC) by compound 48/80 and anti-DNP IgE. Moreover, KHS had a significant inhibitory effect on anti-DNP IgE-induced tumor necrosis factor-alpha (TNF-alpha) secretion from RPMC. These results indicate that KHS inhibits immediate type allergic reactions by inhibition of histamine release and TNF-alpha secretion from mast cells in vivo and in vitro.

Animals↗
PubMed1998

Simultaneous HLA Class I and Class II antibodies screening with flow cytometry.

A flow cytometric method of simultaneously screening both HLA Class I and Class II panel reactive antibodies (PRA) was developed using a pool of 30 different Class I and 30 different Class II microbeads coated with purified HLA antigens. The antibodies in the serum that react specifically to the coated HLA antigens are detected by using a FITC-conjugated antibody against human IgG. Percent PRA can be determined by the percentage of microbeads that react positively to the serum. There is no cross-reactivity between the Class I and Class II microbeads. A mixture of Class I and Class II microbeads can be distinguished by their different fluorescent properties on the flow cytometry analysis. Thus, both Class I and Class II PRA can be detected from a single tube reaction.

Antibodies↗
PubMed1998

Evaluation of the platysma interlocking suture sling for rhytidectomy.

PURPOSE: The purpose of this study was to evaluate the complication rate and the clinical results of the platysma interlocking suture sling for rhytidectomy patients. PATIENTS AND METHODS: In the first part of this study, the charts and photographs of 29 patients who underwent rhytidectomy with the platysma interlocking suture sling were reviewed for complications. The parameters included infection, rupture of the sutures, extrusion of the sutures, prolonged tightness around the neck, and nerve injury. In the second part, the patients' neck deformities were classified into three types: mild (type 1), moderate (type 2), and severe (type 3). The changes in the preoperative and postoperative cervicomental angles were compared between the patients who underwent rhytidectomies with the platysma interlocking suture sling (group 1) and those patients who underwent rhytidectomies only (group 2). RESULTS: The complication rate was found to be minimal. Only one case of prolonged tightness around the neck was noted; there was no other complication. All of the patients, regardless of neck classifications, benefited from rhytidectomy, whether or not the platysma interlocking suture sling was used. However, when comparisons were made between group 1 and group 2 patients in their specific neck deformity categories, it was found that the patients with the severe (type 3) neck deformity benefited most when the platysma interlocking suture sling was used in conjunction with the rhytidectomy procedure. CONCLUSION: The platysma interlocking suture sling has a low morbidity rate and is helpful in reconstruction of patients with the type 3 neck deformity.

Adipose Tissue↗
PubMed1998

Analysis of cocaine chronotoxicology in an urban ED.

To describe the chronotoxicology of cocaine and its potential impact on emergency department (ED) staffing and services, Drug Abuse Warning Network (DAWN) data from a single urban university ED were retrospectively reviewed. The DAWN data reviewed spanned an 11-year period (1/1/83 through 12/31/93), and 3,762 patients were enrolled. Patients were included if the ED records included documentation of recent cocaine abuse prior to presentation to the ED. Of the 3,762 study patients, 1,609 (43%) had documentation of recent cocaine use: 506 (32%) had used cocaine alone, 614 (38%) had used cocaine and ethanol in combination, and 489 (30%) had used cocaine in combination with other drugs. For all patients using cocaine, there were two significant rhythms (P < .05) identified: a circadian rhythm that peaked at 1800 and a 12-hour rhythm that peaked at approximately noon and midnight. A significant rhythmicity was found among cocaine-using patients who presented during the study period. Increased or shift-adjusted staffing focusing specifically on psychosocial services, detoxification, and security during these peak hours may provide more efficient emergent care for this subpopulation of patients.

Adolescent↗
PubMed1998

The photoprotective effect of 1,25-dihydroxyvitamin D3 on ultraviolet light B-induced damage in keratinocyte and its mechanism of action.

We investigated the photoprotective effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) both in vivo and in vitro, revealing its relationship with glutathione, a well-known antioxidant. We also probed into the possible mechanism of photoprotection of 1,25(OH)2D3 through immunohistochemical study for metallothionein (MT). At the same time, endogenous antioxidant effect of 1,25(OH)2D3 was examined. Survival of cultured human keratinocytes was decreased when the cells were irradiated with ultraviolet light-B (UVB) at doses above 30 mJ/cm2. But in the presence of 1,25(OH)2D3 (12 nM), the decrease of survival of keratinocytes by UVB was diminished. The formation of sunburn cells by UVB irradiation in the skin of ICR mice was inhibited by topical application of 1,25(OH)2D3, regardless of prior glutathione depletion. Immunohistochemical staining revealed that 1,25(OH)2D3 induced the expression of MT, a potent radical scavenger, mainly in the basal layer of ICR mice skin. 1,25(OH)2D3 neither inhibited peroxidation of plasma lipids nor interacted with superoxide, nor removed hydrogen peroxide as an antioxidant. These findings suggest that 1,25(OH)2D3 has photoprotective effect not related with glutathione or its endogenous antioxidant property. Rather, it could be attributed to 1,25(OH)2D3-induced MT and its capacity to prevent radical-related damage in UVB irradiation.

Animals↗
PubMed1998

Structural alterations and conformational dynamics in Holliday junctions induced by binding of a site-specific recombinase.

Binding of a cleavage-incompetent mutant of the Flp recombinase induces a roughly square-planar geometry in synthetic immobile Holliday junctions. The branch points, which are rigidly fixed in these junctions in their free forms, tend to be more flexible in their protein-bound forms. Our results (1) suggest a plausible mechanism for the switching of the recombination complex from the Holliday-forming mode to the Holliday-resolving mode, (2) provide a rationale for previous observations that Flp resolves preformed immobile Holliday structures in the parental or in the recombinant mode in a relatively unbiased manner, and (3) accommodate two modes of DNA cleavage by Flp (transhorizontal or transdiagonal) in Holliday substrates.

Bacterial Outer Membrane Proteins↗