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Biomedical subjects

H B Lee

Publications and source records attributed to H B Lee.

At least 91 records · Page 5Linked to original sources
PubMed1998

Effect of prolonged subcutaneous implantation of peritoneal catheter on peritonitis rate during CAPD: a prospective randomized study.

We conducted a prospective randomized controlled study to confirm our earlier observation that prolonged subcutaneous implantation of peritoneal catheter reduced peritonitis rate when compared to retrospective data from patients with catheters placed by conventional access technique. A total of 60 patients were randomized into two groups: 30 patients had catheters left implanted subcutaneously for 6 weeks (I) and the other 30 patients had catheters inserted by conventional technique and had 6 weeks of break-in period (C). Subgroups of 15 patients each with new and conventional techniques used Y-connector (IY, CY) and remaining patients used standard spikes (IS, CS). Mean age was 47.7 years (range 16-71); 61.0% were male and 44.1% diabetics. Peritonitis, exit site infection, simultaneous peritonitis and exit site infection, and complication related to Staphylococcus or Pseudomonas infections were observed for up to 2 years in each patient after initiation of bag exchange or until termination of CAPD by transfer to hemodialysis or by death. Total duration of observation was 493.2 patient-months for new access technique and 409.6 patient-months for conventional technique. Patients in IY group had the lowest incidence of peritonitis (1/14.9 patient-months) and exit site infection (1/16.8 patient-months) among four subgroups. Peritonitis rate in IY was significantly lower compared to CY or CS. The total peritonitis-free period in those patients who did not experience peritonitis during the observation period was also significantly longer in IY (120 patient-months) than in CY (26 patient-months), IS (10.6 patient-months), or CS (10.4 patient-months). Simultaneous peritonitis and exit site infection was observed in none of IY group but 3 episodes in CY, 4 episodes in IS, and 3 episodes in CS. The rates of complications related to Staphylococcus aureus and Pseudomonas infections were also significantly lower in IY than in CY, IS, or CS. Technique survival did not differ between the two groups. The present results confirm our previous observation that the new access technique reduces the incidence of peritonitis probably by reducing infection via periluminal route. The Y-connector system further reduces peritonitis rate by reducing infection via intraluminal route.

Adolescent↗
PubMed1998

Platelet adhesion on the gradient surfaces grafted with phospholipid polymer.

We have synthesized omega-methacryloyloxyalkyl phosphorylcholine (MAPC) polymers as new blood-compatible materials, with attention to the surface structure of the biomembrane and investigated their blood compatibility. The blood compatibility observed on the MAPC polymers is due to their strong affinity to phospholipids. When the blood comes in contact with the MAPC polymer, phospholipids in the plasma preferentially adsorb on the surface, compared with the plasma proteins or cells. The adsorbed phospholipids construct a biomembrane-like structure on the MAPC polymer surface. The MAPC polymers then have an excellent blood compatibility. In this study, we prepared a gradient poly(MAPC)-grafted polyethylene (PE) surface using a corona discharge treatment method to clarify the effect of the chemical structure of the MAPC unit on the blood compatibility of the MAPC polymers. The surface composition of MAPC and the hydrophilicity on the poly(MAPC)-grafted PE surface were determined by X-ray photoelectron spectroscopic (XPS) analysis and contact angle measurement with water, respectively. The phosphorus/carbon (P/C) ratio determined by the XPS analysis increased, but the water contact angle decreased with increasing corona irradiation energy. These results indicated that the surface density of the MAPC unit was increased. More than 2.5 cm from the starting point of the corona irradiation, the P/C ratio and water contact angle of the surface achieved a constant level. Thus, the surface was completely covered with the grafted poly(MAPC) chain. The effect of the methylene chain length of the MAPC unit on surface properties was also observed. The phospholipid polar group of the MAPC unit was effectively exposed on the surface as the chain length became longer. Moreover, the hydrophobicity of the surface was increased with the increase in the methylene chain length of the MAPC unit. The number of platelets adhering to the poly(MAPC)-grafted PE surface was reduced from the same point where the P/C ratio became constant.

Animals↗
PubMed1998

Platelet and cell interactions on gold sputter-deposited polymeric surfaces.

Surface treatment as gold sputter-deposited treatment onto various polymeric surfaces has been investigated to improve the cell-, tissue- and blood-compatibility. Surface treated samples were characterized by measurement of contact angle goniometer and electron spectroscopy for chemical analysis (ESCA). The contact angles on the gold-coated polymeric surfaces decreased from 95-65 degrees to around 50 degrees, i.e., increased hydrophilicity due to incorporation of gold thin layer. From the results of ESCA analysis of the modified polymeric surfaces, surface modification by the gold-sputter method was successfully performed. Morphology of the adhered platelets on the gold-coated polymeric surfaces showed lesser activating than control, and the number of adhered platelets surface modified samples decreased with decreasing water contact angle. Fibroblast cell adhesion and growth on the gold-coated polymeric surfaces were more active than those of control. It seems that surface wettability and surface chemistry of gold play important roles for platelet adhesion and cell adhesion, spreading and growth.

3T3 Cells↗
PubMed1997

EGF inhibits expression of WDNM1 and sulfated glycoprotein-2 genes in mammary epithelial cells.

We have previously shown that expressions of ferritin heavy chain (FHC), WDNM1, and sulfated glycoprotein-2 (SGP-2) genes are induced at an involution stage of mammary gland. Here we studied the effect of lactogenic hormones and EGF on the expression of involution-induced genes in HC11 mammary epithelial cells. Insulin, dexamethasone, prolactin, and its combinations did not affect expression of the genes. When cells were cultured in growth medium containing EGF, expression of WDNM1 and SGP-2 genes was strongly inhibited in a dose- and time- dependent manner, whereas expression of FHC gene was not influenced by EGF. Results demonstrate that EGF inhibits expression of WDNM1 and SGP-2 genes in mammary epithelial cells.

Animals↗
PubMed1997

The 5'-upstream region of the rat phospholipase C-beta 3 gene contains two critical Sp1 sites and an HIV Inr-like element.

The 5'-upstream region of the rat phospholipase C-beta 3 gene (PLC-beta 3) has been cloned and characterized. Sequence analysis of the 5'-upstream region showed that it contains a GC-rich region (-166 to +1: 79%) and multiple binding sites for the transcription factors Sp1, AP-1 and AP-2, but does not contain a canonical TATA box. Primer extension analysis of total RNA isolated from rat glial cell C6Bul revealed that single transcription start point (tsp) is located at an initiator (Inr) element similar to that found in the HIV promoter. Gel mobility shift and competitive mobility shift assays indicated that this Inr element forms a DNA-protein complex with the HIV Inr-binding protein, LBP-1/CP2 or a homologue. In order to localize functional elements of the 5'-upstream region of the rat PLC-beta 3 gene, 5'-deletion fragments were cloned into a chloramphenicol acetyltransferase (CAT) reporter vector. Transient transfection analyses of the 5'-deletion mutants identified a crucial promoter element located at -128 to -14. Supershift mobility assays, site-directed mutagenesis and DNase I footprints indicated that Sp1 binds to three GC boxes within the sequence between -128 and -14 of the PLC-beta 3 promoter. Transient transfection analyses of promoter constructs containing site-specific mutation(s) of these three GC boxes demonstrated that two GC boxes, located proximal to the tsp, are important elements for normal promoter activity.

Animals↗
PubMed1997

Plasma protein adsorption and platelet adhesion onto comb-like PEO gradient surfaces.

Comb-like polyethylene oxide (PEO) surfaces were prepared on low-density polyethylene (PE). The comb-like PEO chain density was changed gradually along the sample lengths by corona discharge treatment with gradually increasing power and the following graft copolymerization of poly(ethylene glycol) monomethacrylate macromers (PEO-MA). The macromers with different PEO repeat unit, 1, 5, and 10, were used. The prepared comb-like PEO gradient surfaces were characterized by water contact angle, Fourier transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. All these measurements indicated that the PEO chains are grafted on the PE surface with gradually increasing density of PEO. Plasma protein adsorption and platelet adhesion on the PEO gradient surfaces decreased with increasing PEO chain length and surface density. As observed by scanning electron microscopy, PEO10-MA-grafted surface with high PEO density was very effective in preventing protein adsorption and platelet adhesion and did not activate the platelets.

Adsorption↗
PubMed1997

Development and characterization of an alginate-impregnated polyester vascular graft.

Alignate gels are known to be biocompatible, degradable, and nontoxic. In this study, sodium alginate was impregnated into a porous, knitted polyester graft (Microvel double velour graft) 6 mm in diameter. The alginate-impregnated graft was investigated in vitro and in vivo to evaluate its potential for use as a new vascular graft impervious to blood, while retaining high porosity for tissue ingrowth and biological healing. For in vitro investigation, the coating weight, water permeability, morphology, and mechanical properties of the alginate-impregnated grafts were compared to those of control or commercially available collagen-impregnated (Hemashield) grafts. The water permeability of the controls (1846 mL/min.cm2 at 120 mm Hg) was reduced > 99% by the alginate impregnation, rendering the graft impervious to blood. The coating weight of the alginate was 45 mg/g of graft, producing a much lower value than that of the collagen-impregnated model (310 mg/g). For in vivo investigation, the alginate-impregnated grafts were implanted in the aorta of mongrel dogs without preclotting for scheduled periods ranging from 4 h to 6 months. The control grafts after preclotting and the collagen-impregnated grafts without preclotting were also implanted for 3 and 6 months for comparison. Gross observation of the explanted grafts and histologic examination of the representative sections were conducted for three types of grafts using a light microscope after hematoxylin-eosin staining. No significant differences were observed between the histologic appearance of the alginate-impregnated grafts and that of the preclotted and collagen-impregnated grafts in terms of the degree of inflammation, foreign-body giant cell reaction, and intimal fibrosis. Endothelial-like cells were present on the midsections of all the grafts after 3 months of implantation. The resorption rate of alginate impregnated into the graft was also examined after staining the sections with periodic acid-Schiff reagent, Toluidine blue, and Alcian blue, which are specific for alginates. The staining alginate was partially visible between the graft fabrics up to 1 month after implantation, but was completely resorbed after 3 months. This preliminary study demonstrated that the use of an alginate as a biological sealant instead of proteins such as collagen, gelatin, and albumin may be a feasible approach to developing imprevious textile arterial prostheses, since the proteins have been reported to be generally unstable, hard to obtain in pure forms, not easy to crosslink and control resorption rate, and difficult to render compatible with standard storage and sterilization procedures.

Alginates↗
PubMed1997

Interaction of cells on chargeable functional group gradient surfaces.

Functional group gradient surfaces where the surface density of grafted functional groups changes gradually along the sample length were prepared on low density polyethylene (PE) sheets by corona discharge treatment with gradually increasing power and graft copalymerization of acrylic acid (AA), sodium p-styrene sulphonate (NaSS), and N,N-dimethyl aminopropyl acrylamide (DMAPAA). AA and NaSS are negatively chargeable and DMAPAA is positively chargeable in phosphate buffered saline or cell culture medium at pH 7.3-7.4. The functional group gradient surfaces were characterized by the measurement of water contact angle, Fourier transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. All these measurements indicated that the functional groups were grafted on the PE surfaces with gradual increase of their density. The interaction of Chinese hamster ovary cells with the functional group gradient surfaces along the sample length was investigated. The cells that had adhered and grown on the surfaces were counted and observed by scanning electron microscopy. It was observed that a greater quantity of the cells had adhered and grown onto the positions with moderate density of the functional groups. This may be related to the hydrophilicity of the surface. The DMAPAA-grafted surface showed a large amount of cell attachment probably owing to the positive charge character, while the AA-grafted surface, which is negatively charged, showed poor cell attachment, as expected. The NaSS-grafted surface which is also negatively charged showed a large amount of cell attachment. This may be closely associated with the existence of an aromatic ring close to the ionizable group in NaSS. It seems that surface functional groups and their charge character as well as wettability play important roles for cell adhesion, spreading, and growth.

Amines↗
PubMed1997

Chaperone-like function of lipocortin 1.

Lipocortin 1 (LC1) is a 37 kDa member of the annexin family of proteins. It has been proposed to act as a mediator of some of the actions of glucocorticoids in anti-inflammatory and immune suppressive functions. LC1 has been shown to play a role in cell proliferation, apoptosis, and differentiation. However, the exact biological functions of LC1 still remain obscure. Here it is shown that LC1 displays a chaperone-like function. Stoichiometric amounts of LC1 suppressed thermally induced inactivation and aggregation of the test enzymes citrate synthase and glutamate dehydrogenase. LC1 was also effective in refolding guanine hydrochloride-denatured glutamate dehydrogenase, as judged by circular dichroism spectroscopy.

Animals↗
PubMed1997

Unilateral multilayered musculocutaneous V-Y advancement flap for the treatment of pressure sore.

We have devised a modified technique using the gluteus maximus musculocutaneous flap as multilayered sliding V-Y advancement to cover pressure sores on the sacral area. Nine patients with relatively large (average 7 x 7 cm) sacral grade IV pressure sores underwent unilateral multilayered V-Y advancement flap. All patients were followed for a minimum of 8 weeks. The mean postoperative follow-up was 32.3 months, with a range of 24 to 39 months. Using this technique, the success of surgery, i.e., the percentage of sores that healed, was 100 percent in our patients. The advantages of this technique include sufficient advancement of the flap, coverage of large ulcer defects using only a unilateral musculocutaneous flap, and preservation of the contralateral gluteus maximus muscle for future use.

Aged↗
PubMed1997

Identification of urinary dipeptidase as the released form of renal dipeptidase.

Amphipathic and hydrophilic forms of human renal dipeptidase and urinary dipeptidase were purified by affinity chromatography using cilastatin, a dipeptidase inhibitor, as the ligand. The sequence analyses of the first ten amino acids of renal and urinary dipeptidases were shown to be identical, and they are Asp-Phe-Phe-Arg-Asp-Glu-Ala-Glu-Arg-Ile. Unambiguous results of amino acid sequencing, the molecular weight of native protein (190 kD), the molecular weight of subunit (47.7 kD) and a single band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicate that the enzymes are composed of homotetramers. This is the most direct evidence that urinary dipeptidase is the released form of renal dipeptidase. In fact, they are the same enzymes.

Amino Acid Sequence↗
PubMed1997

Differences in immunophenotyping of mucosal lymphocytes between ulcerative colitis and Crohn's disease.

OBJECTIVES: Immunologic studies have characterized the numbers and types of inflammatory cells in diseased inflammatory bowel disease (IBD) mucosa but have yielded conflicting results regarding intestinal lymphocytes activation in IBD. We investigated the levels of lymphocytes subsets, interleukin-2 receptor, transferrin receptor, and T cell receptors in mainly isolated lamina propria lymphocytes. Including intraepithelial lymphocytes of normal colonic mucosa or IBD (ulcerative colitis and Crohn's disease) mucosa to understand the pathogenesis of IBD. We have results from this study. RESULTS: 1) In comparing ulcerative colitis with control, IL-2R (p < 0.05), TR (p < 0.01), and CD3/HLA-DR (< 0.05) showed a significant increase. 2) In comparing Crohn's disease with control, CD3 (P < 0.05), TCR alpha/beta (p < 0.01) and TCR gamma/delta (p < 0.05) showed a significant decrease. 3) In comparing Crohn's disease with ulcerative colitis, CD19 (p < 0.01), TR (p < 0.01), TCR alpha/beta (p < 0.01) and TCR gamma/delta (p < 0.05) showed a significant decrease. CONCLUSION: From these results, there are increased T cell markers, IL-2R, TR, and CD3/HLA-DR in UC, but differently, decreased CD3, TCR alpha/beta and TCR gamma/delta in CD compared with control. In addition, definitive differences in lymphocytes markers, CD19, TR, TCR alpha/beta and TCR gamma/delta, which are higher in UC than in CD, may elucidate the different immunopathogenesis between UC and CD.

Adult↗
PubMed1997

Single-sample methods to measure GFR with technetium-99m-DTPA.

UNLABELLED: Many single-sample methods have been suggested to simplify the methodology of glomerular filtration rate (GFR) measurement. The relative accuracy of these competing methods is still not clear for clinical practice. METHODS: Fifty-four GFR studies with 99mTc-DTPA were performed on 37 adult patients (serum creatinine 0.8-10 mg/dl). Each study included a UV/P, plasma clearance method (three-sample) and single-sample methods. The single-sample methods used were those of Christensen and Groth (modified by Watson), Constable, Dakubu, Groth and Aasted, Jacobsson, Morgan, Russell and Tauxe. RESULTS: When the GFR > or = 30 ml/min (n = 26), all of the single-sample methods were highly correlated with UV/P. The correlation of the single-sample method with the plasma clearance was higher than with UV/P. In this group (GFR > or = 30 ml/min), the Groth 4-hr sample method had the best value of both absolute difference and percent absolute difference (mean +/- s.e. = 11.05 +/- 2.51 ml/min and 14.08% +/- 2.43%, respectively). Most single-sample methods do not perform well at GFR < 30 ml/min (n = 28), and none of them has a good correlation with UV/P or plasma clearance at this level of renal function. However, the Groth and Aasted's 4-hr sample method was the best compared with others (mean +/- s.e. = 8.43 +/- 1.30 ml/min for absolute difference, and 65.91% +/- 16.70% for percent absolute difference). CONCLUSION: Single-sample methods may not correctly predict GFR in advanced renal failure. Groth and Aasted's method with 4-hr plasma sample has both the lowest mean absolute difference and percent absolute difference in both the group with GFR > or = 30 ml/min and GFR < 30 ml/min. All methods perform acceptably at GFR > or = 30 ml/min.

Adult↗
PubMed1997

Cell and platelet adhesions on plasma glow discharge-treated poly(lactide-co-glycolide).

Surface treatment, such as plasma glow discharge treatment, onto poly(lactide-co-glycolide) (PLGA) has been investigated to improve the cell-, tissue- and blood-compatibility. Surface-treated samples were characterized by measurement with a contact angle goniometer and electron spectroscopy for chemical analysis (ESCA). The contact angles on the plasma-treated PLGA surfaces decreased with increasing plasma exposure time from 92 degrees to about 30 degrees, i.e., increased hydrophilicity. From the results of ESCA analysis of plasma-treated films, the incorporation of oxygen molecules into plasma onto the PLGA surface was observed. Cell adhesion and growth on plasma-treated PLGA surfaces were more active than on the control. Furthermore, the maximum adhesion and growth of cells in moderate hydrophilicity were investigated. Morphology of the adhered platelets on the plasma-treated PLGA surface showed less activity than on the control, and the number of adhered platelets on the plasma-exposed PLGA sample decreased with decreasing water contact angle. It seems that surface wettability of PLGA plays an important role in cell adhesion, spreading and growth, and platelet adhesion.

3T3 Cells↗
PubMed1996

Augmentation of tumor metastasis by platelet-activating factor.

The effect of platelet-activating factor (PAF) on experimental pulmonary metastasis by the B16F10 murine melanoma and the possible involvement of PAF in the activities of tumor necrosis factor alpha (TNF-alpha) and interleukin 1alpha (IL-1alpha) in tumor metastasis were investigated. i.p. injection of PAF enhanced the lung colonization in a dose- and time-dependent manner. PAF enhanced lung colonization when it was administered after, but not before, B16F10 inoculation. Multiple injections of PAF were more effective than a single injection. Neutralization of endogenous PAF with PAF antagonist BN50739 decreased lung colonization, suggesting that endogenous PAF plays an important role in pulmonary metastases. A single i.p. injection of TNF-alpha or IL-1alpha caused a marked enhancement in lung colonization. TNF-alpha- and IL-1alpha-mediated enhancement in lung colonies was significantly inhibited by BN50739. These results demonstrate that PAF has a metastasis-enhancing effect and is a mediator of the metastatic activities of TNF-alpha and IL-1alpha.

Animals↗
PubMed1996

Enhancement of thermostability and catalytic efficiency of AprP, an alkaline protease from Pseudomonas sp., by the introduction of a disulfide bond.

A site-directed mutagenesis in AprP, an alkaline protease isolated from Pseudomonas sp. KFCC 10818 was carried out in order to obtain increased thermostability. Sites for cysteine substitutions to form disulfide bond within AprP were chosen by comparing the sequences with aqualysin I, an alkaline thermostable serine protease whose disulfide bonds seems to be important for its thermostability. Gly199 and Phe236 residues were each replaced with cysteine by site-directed mutagenesis. The G199C/F236C mutant enzyme appeared to form a disulfide bond spontaneously during its expression. It also showed improved kinetic parameters for the hydrolysis of a synthetic peptide substrate at pH 8.5 and 10.5 compared to those of the wild-type enzyme. The half-life of the G199C/F236C mutant was found to be 2 to 4.8 times longer than that of wild-type under various experimental conditions, except when tested under reducing condition, where no significant differences in the half-life of the two types were observed. Therefore, it is concluded that the introduction of the disulfide bond enhanced the thermostability and the catalytic efficiency of the enzyme AprP.

Alkaline Phosphatase↗
PubMed1996

In situ detection of hepatitis C virus RNA in liver tissue using a digoxigenin-labeled probe created during a polymerase chain reaction.

The cellular localization of hepatitis C virus (HCV) RNA in liver tissue was studied by nonisotopic in situ hybridization using a digoxigenin-labeled cDNA probe created during a polymerase chain reaction on samples from 16 patients with chronic HCV infection. Hybridization signals were recognized in the cytoplasm of the hepatocytes, and a few hepatocytes had hybridization signals in the nucleus as well. HCV RNA positive hepatocytes were found in 1 of 9 patients with chronic persistent hepatitis, 2 of 5 patients with chronic active hepatitis, and in each of 2 patients with chronic active hepatitis and cirrhosis. Positive signals were found in many hepatocytes within the lobule in liver sections of patients with advanced chronic active hepatitis. A number of HCV RNA positive hepatocytes were found in nodules, but not in the area of fibrosis. On the other hand, positive signals were found in a few hepatocytes scattered in the lobule in a patient with chronic persistent hepatitis. The mean ALT levels in the patients with positive signal (175.6 +/- 44.2 U/L) were significantly higher than in those without a signal (70.27 +/- 16.1 U/L) (P < 0.05). The findings suggest that a larger amount of HCV may be present during the advanced than during the early stages of type C hepatitis and nonisotopic in situ hybridization using a digoxigenin-labeled HCV cDNA probe created during a polymerase chain reaction deserves wider application for the detection of HCV replication in specimens.

Adult↗