PubMed Health⌕ Search

Biomedical subjects

K H Lee

Publications and source records attributed to K H Lee.

At least 19 recordsLinked to original sources
PubMed1992

Antitumor agents. 134. New shiraiachrome-A- and calphostin-C-related perylene derivatives as cytotoxic and antiviral agents and inhibitors of protein kinase C.

Shiraiachrome-A and -B have been isolated from the mycelium of the Chinese bamboo fungus Shiraia bambusicola as the cytotoxic principles. A series of new perylene derivatives (7-27) related to Shiraiachrome-A and -B as well as Calphostin-C have been synthesized and evaluated for their cytotoxicity, antiviral activity, and inhibitory activity against protein kinase C. The results indicated that 11 and 12 are potent cytotoxic agents against HCT-8, RPMI-7951, and TE-671 solid tumor cells, whereas 24 and 26 demonstrated strong antiviral activity against HSV-1 and HSV-2. Compound 10 is an inhibitor of protein kinase C.

Animals↗
PubMed1992

Regulation of vascular cell adhesion molecule 1 on human dermal microvascular endothelial cells.

Vascular endothelial cell adhesion molecule 1 (VCAM-1) is an adherence molecule that is induced on endothelial cells by cytokine stimulation and can mediate binding of lymphocytes or tumor cells to endothelium. Because these interactions often occur at the level of the microvasculature, we have examined the regulation of expression of VCAM-1 in human dermal microvascular endothelial cells (HDMEC) and compared it to the regulation of VCAM-1 in large vessel human umbilical vein endothelial cells (HUVEC). Both cell populations were judged pure as assessed by expression of von Willebrand factor and uptake of acetylated low density lipoprotein. Expression of VCAM-1 was not detectable on either unstimulated HDMEC or HUVEC when assessed by ELISA or flow cytometry. Stimulation of either HDMEC or HUVEC with TNF-alpha resulted in a time- and dose-dependent induction of VCAM-1. However, although TNF-alpha-induced cell surface and mRNA expression of VCAM-1 in HDMEC was transient, peaking after 16 h of stimulation, TNF stimulation led to persistently elevated cell surface expression of VCAM-1 on HUVEC. IL-1 alpha also induced cell surface expression of VCAM-1 on HUVEC in a time- and dose-dependent manner, but stimulation of HDMEC with IL-1 alpha at doses up to 1000 U/ml failed to induce significant cell surface expression. However, IL-1 alpha induced time- and dose-dependent increases in ICAM-1 on HDMEC. Similarly, IL-4 induced VCAM-1 expression and augmented TNF-alpha-induced expression on HUVEC but did not affect VCAM-1 expression on HDMEC. Binding of Ramos cells to cytokine-stimulated endothelial cell monolayers correlated with VCAM-1 induction. Increased binding was seen after stimulation of HDMEC with TNF-alpha, which was blocked by anti-VCAM-1 mAb, but no increases in binding were noted after stimulation of HDMEC monolayers with IL-1 alpha. These data provide additional evidence for the existence of endothelial cell heterogeneity and differences in cell adhesion molecule regulation on endothelial cells derived from different vascular beds.

Cell Adhesion Molecules↗
PubMed1992

Prevention of binding of rgp120 by anti-HIV active tannins.

Several tannins with anti-HIV activity have been described previously (Nonaka et al., J Nat Prod 53: 587-595, 1990). We have shown that the tannins chebulinic acid and punicalin were able to block the binding of HIV rgp120 to CD4. These compounds were not toxic to stimulated human peripheral blood lymphocytes at concentrations ten times above their maximal effective concentration.

Antiviral Agents↗
PubMed1992

Antitumor agents. 123. Synthesis and human DNA topoisomerase II inhibitory activity of 2'-chloro derivatives of etoposide and 4 beta-(arylamino)-4'-O-demethylpodophyllotoxins.

The 2'-chloro derivatives of etoposide and 4 beta-(arylamino)-4'-O-demethylpodophyllotoxins have been synthesized and evaluated for their inhibitory activity against the human DNA topoisomerase II as well as for their activity in causing cellular protein-linked DNA breakage. The results showed that none of the compounds are active as a result of the C-2' chloro substitution on ring E. This would suggest that the free rotation of ring E is essential for the aforementioned enzyme inhibitory activity. In addition, these 2'-chloro derivatives showed no significant cytotoxicity (KB).

Antineoplastic Agents↗
PubMed1992

Antitumor agents. 124. New 4 beta-substituted aniline derivatives of 6,7-O,O-demethylene-4'-O-demethylpodophyllotoxin and related compounds as potent inhibitors of human DNA topoisomerase II.

A series of 6,7-O,O-demethylene-4'-O-demethyl-4 beta-(substituted anilino)-4-desoxypodophyllotoxins (18-23), 6,7-O,O-demethylene-6,7-O,O-dimethyl-4'-O-demethyl-4 beta-(substituted anilino)-4-desoxypodophyllotoxins (28-31), and their corresponding 4'-O-methyl analogues (12-17 and 24-27) have been synthesized and evaluated for their inhibitory activity against the human DNA topoisomerase II as well as for their activity in causing cellular protein-linked DNA breakage. Compounds 18-23 are 2-fold more potent than etoposide and compounds 12, 16, 17, 30, and 31 are as active as etoposide in their inhibition of the human DNA topoisomerase II. Compounds 19 and 20 and 29-31 are as active or more active than etoposide in causing protein-linked DNA breakage. These results indicate that a free C-4' hydroxy group is essential for the DNA breakage activity, and that the hydroxyl groups at C-6 and -7 positions may be involved in an interaction which is responsible for the inhibitory activity of DNA topoisomerase II. The maintenance of an intact methylene dioxy-type ring-A system would contribute to enhanced activity. In addition, the sterically less hindered substitution at C-6 and C-7 positions may be important for optimal interactions with DNA topoisomerase II. There is no correlation between the ability of these compounds to inhibit DNA topoisomerase II and their ability to cause protein-linked DNA breaks in cells. This may relate to the difference in uptake of these compounds. The better correlation was observed between the protein-linked DNA breaks and the cytotoxicity in KB cells of these compounds.

Aniline Compounds↗
PubMed1992

Human dermal microvascular endothelial but not human umbilical vein endothelial cells express CD36 in vivo and in vitro.

CD36 is an 88-kDa glycoprotein that has been identified on platelets, monocytes, and some endothelial cells. Experimental evidence suggests that CD36 mediates the binding of Plasmodium falciparum-infected RBC to a variety of cells, and therefore may play a role in the vascular complications associated with malaria. Additionally, CD36 may also bind the extracellular matrix proteins thrombospondin and collagen. Human umbilical vein endothelial cells have been used in in vitro models examining the binding of P. falciparum RBC to endothelial cells, but they do not consistently express cell surface CD36. Inasmuch as human dermal microvascular endothelial cells (HDMEC) differ in a variety of ways from large vessel endothelial cells, we have examined HDMEC for cell surface expression of CD36 in vivo and in vitro. Direct immunofluorescence of skin showed bright staining of HDMEC with antibody recognizing CD36 and flow cytometric analysis of cultured HDMEC revealed cell surface expression. In contrast, large vessel endothelial cells were not stained with antibody recognizing CD36 in vivo and cultured cells derived from umbilical vein failed to express cell surface CD36 in vitro. Western immunoblots of lysates of HDMEC but not human umbilical vein endothelial cells demonstrated an 88-kDa protein that comigrated with CD36 from platelets. Functional studies demonstrated that adherence of PRBC to HDMEC was inhibited up to 66% by mAb recognizing CD36. Furthermore, the expression of CD36 on HDMEC was increased in a dose- and time-dependent manner by IFN-gamma, and was decreased by protein kinase C agonists. These data demonstrate that HDMEC express functionally active CD36 and this expression can be positively and negatively regulated by soluble factors. This study demonstrates that HDMEC are useful in the study of CD36-mediated binding of PRBC to endothelial cells in vitro and provides further evidence of distinct phenotypic differences between HDMEC and large vessel endothelial cells.

Antigens, CD↗
PubMed1992

Betaine:homocysteine methyltransferase from rat liver: purification and inhibition by a boronic acid substrate analog.

Betaine:homocysteine methyltransferase (BHMT) from rat liver has been highly purified by an efficient procedure requiring only two chromatographic steps: Sephadex G-100 chromatography and fast protein liquid chromatography chromatofocusing. A 170-fold purification and 7.5% overall yield were achieved. Chromatofocusing yielded three active forms of BHMT with pI values near 8.0, 7.6, and 7.0. The subunit molecular weight of each active form is 45,000 Da as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the native enzyme has a molecular weight of 270,000 as determined by exclusion chromatography. The stability of the purified enzyme was found to be potentiated by the presence of 1 mM dimethylglycine and 1 mM homocysteine. Boronate analogs of betaine (pinanyl N,N,N-trimethylaminomethaneboronate) (4) and dimethylglycine (pinanyl N,N-dimethylaminomethaneboronate) were synthesized from pinanyl iodomethaneboronate (3) and trimethylamine or dimethylamine, respectively. The free acid of the betaine analog (5) was reversibly generated from (4). The inhibition of BHMT by (5) appears competitive with a Ki = 45 microM. Since the Km for betaine measured with the purified enzyme is near 0.1 mM, the boronic acid analog of betaine appears to function effectively as a substrate analog inhibitor of BHMT. The analog does not appear to act as a methyl donor to homocysteine when (5) is substituted for betaine in the enzyme reaction. In addition, an enzyme assay based upon C3-cyano reverse phase HPLC detection of the o-phthalaldehyde derivative of methionine was developed as an alternative to the standard radiochemical assay. Betaine:homocysteine methyltransferase in the picomole range can be quantitated using this assay as indicated by a linear response of enzyme activity to protein concentration.

Animals↗
PubMed1992

Cardiovascular responses in the normotensive rat produced by intravenous injection of gambirine isolated from Uncaria callophylla B1. ex Korth.

Among several alkaloids, including dimeric indoles, isolated from Uncaria callophylla, gambirine which is an alkaloid unique to this plant, has been found to be another hypotensive principle from the plant. Intravenous injections of gambirine in the dose range of 0.2 to 10.0 mg/kg caused a dose-related fall in both systolic and diastolic blood pressures as well as heart rate. At all doses gambirine showed a prompt onset of action and at the higher doses (5.0-10 mg/kg), marked persistence of hypotension accompanied by severe bradycardia were observed. In addition, higher doses of gambirine produced a more marked decrease in diastolic than systolic pressure while at lower doses both decreased equally. It is suggested that the hypotensive effect of gambirine may be peripheral in origin and is associated, at least in part, with a cardiac action.

Alkaloids↗
PubMed1992

Anti-AIDS agents, 4. Tripterifordin, a novel anti-HIV principle from Tripterygium wilfordii: isolation and structural elucidation.

A new kaurane-type diterpene lactone, tripterifordin [1], has been isolated from the roots of Tripterygium wilfordii. The structure of 1 was elucidated by spectroscopic methods, including the concerted application of a number of 2D nmr techniques that involved the 1H-1H COSY, heteronucleus-detected variants of the heteronuclear chemical shift correlation (HETCOR), phase-sensitive NOESY, and long-range HETCOR. Compound 1 shows anti-HIV replication activity in H9 lymphocyte cells with an EC50 of 1 microgram/ml.

Antiviral Agents↗
PubMed1992

Antitumor agents, 129. Tannins and related compounds as selective cytotoxic agents.

Fifty-seven tannins and related compounds, including gallotannins, ellagitannins, and condensed and complex tannins, were evaluated for their cytotoxicities against human tumor cell lines, including malignant melanoma, lung carcinoma, ileocecal adenocarcinoma, epidermoid carcinoma, malignant melanoma, and medulloblastoma cell lines. Among them, chebulagic acid [1], geraniin [2], sanguiin H-11 [3], 4,5-di-O-galloylquinic acid [12], 1,3,4,5-tetra-O-galloylquinic acid [15], 1(beta)-O-galloylpedunculagin [24], furosin [29], castalagin [38], sanguiin H-2 [34], vescalagin [39], grandinin [40], phyllyraeoidin A [42], (-)-epicatechin 3-O-gallate [50], cinnamtannin B2 [55], and acutissimin A [56] exhibited moderate selective cytotoxicity against PRMI-7951 melanoma cells with ED50 values in the range of 0.1-0.8 microgram/ml. Selective cytotoxicities against the melanoma cells were also observed for strictinin [22], pedunculagin [23], eugeniin [25], elaeocarpusin [28], punicacortein C [37], casuarinin [41], sanguiin H-6 [43], procyanidin B-2 3,3'-di-O-gallate [51], procyanidin C-1 3,3',3"-tri-O-gallate [52], and cinnamtannin B1 [54] with ED50 values of 1-4 micrograms/ml. All of the tannins were found to be inactive (greater than 10 micrograms/ml) against lung carcinoma (A-549), ileocecal adenocarcinoma (HCT-8), epidermoid carcinoma of nasopharnyx (KB), and medulloblastoma (TE-671) tumor cells.

Antineoplastic Agents, Phytogenic↗
PubMed1992

Antitumor agents, 130, Novel 4 beta-arylamino derivatives of 3',4'-didemethoxy-3',4'-dioxo-4-deoxypodophyllotoxin as potent inhibitors of human DNA topoisomerase II.

A series of ortho-quinone analogues 1-28 of podophyllotoxin possessing various C-4 beta-aniline moieties have been synthesized and evaluated for their inhibitory activity against human DNA topoisomerase II, their activity in causing cellular protein-linked DNA breakage, and their cytotoxicity against KB cells. Compounds 8-12, 15, 19, and 23-28 are better than or comparable to etoposide in their inhibition of the human DNA topoisomerase II, while compounds 8-10 and 22 are comparable to or more potent than etoposide in causing DNA breakage. There is an apparent lack of correlation between cytotoxicity and the ability of these compounds to cause protein-linked DNA breaks or inhibit DNA topoisomerase II. This suggests that in addition to the mechanism of the topoisomerase II involving DNA breakages, other mechanisms of action, such as the radical mechanism or the direct adduct formation of the ortho-quinone with DNA or protein, may also involve and account for the apparent KB cytotoxicity. Two different modes of DNA topoisomerase II inhibition for 8-28 were proposed.

Antineoplastic Agents, Phytogenic↗
PubMed1992

Antitumor agents, 135. Structure and stereochemistry of polacandrin, a new cytotoxic triterpene from Polanisia dodecandra.

A new dammarane triterpene, polacandrin [1], has been isolated from Polanisia dodecandra. The structure of 1 was established as 1 beta, 3 alpha, 12 beta, 25-tetrahydroxy-20(S),24(S)-epoxydammarane by chemical and spectroscopic methods, which included the concerted application of a number of 2D nmr techniques that involved 1H-1H COSY, HETCOR, NOESY, and long-range HETCOR. Single-crystal X-ray analysis of polacandrin pentahydrate verified the complete structure and stereochemistry. Polacandrin showed potent cytotoxicities against KB (ED50 = 0.60 microgram/ml), P-388 (ED50 = 0.90 microgram/ml), and RPMI-7951 (ED50 = 0.62 microgram/ml) tumor cells.

Animals↗
PubMed1992

Combination of 5-fluorouracil and recombinant interferon alpha-2B in advanced gastric cancer. A phase I study.

Based on recent preclinical data suggesting synergism between 5-fluorouracil (5-FU) and interferon alpha (IFN-alpha) and clinical activity of the combination therapy in colon cancer, 14 patients with advanced gastric cancer were treated with combination therapy of 5-FU and recombinant interferon alpha-2b (rIFN alpha-2b) (Intron A, Schering, Kenilworth, NJ, U.S.A.). The maximum tolerated dose was 5-FU 750 mg/m2/day given as a continuous infusion daily for 5 days followed by weekly bolus injection of the same initial daily dose, plus rIFN alpha-2b 5 X 10(6) U given subcutaneously 3 times weekly starting day 1 of 5-FU infusion. The dose-limiting toxicities were fatigue/weakness, diarrhea, and neurologic toxicities such as somnolence and confusion. The other common side effects were nausea, fever, leukocytopenia, thrombocytopenia, and the darkening of the skin. Of 13 evaluable patients, 4 had a partial response (duration 6, 14, 24, and 28 weeks). These data suggest that combination therapy of 5-FU plus rIFN alpha-2b is tolerable and has manageable side effects in patients with advanced gastric cancer. Further Phase II study will be needed to define the antitumor activity of this combination.

Adult↗
PubMed1992

VCAM-1-, ELAM-1-, and ICAM-1-independent adhesion of melanoma cells to cultured human dermal microvascular endothelial cells.

We have examined the mechanisms by which tumor cells bind to endothelial cells utilizing cultured melanoma cells and microvascular endothelial cells derived from human dermis (HDMEC). The ability of biologic response modifiers (BRM) to modulate the adhesion of melanoma cells to HDMEC was defined and those results were compared with results from human umbilical vein endothelial cells (HUVEC). SK-MEL-2, WM266-4, and Hs 294T melanoma cells all bound to HDMEC and HUVEC monolayers and adherence of melanoma cells was enhanced in a dose- and time-dependent manner by the treatment of HDMEC with interleukin 1 (IL-1) alpha or tumor necrosis factor (TNF) alpha. Similar increases in binding to HDMEC or HUVEC were induced after BRM stimulation, although baseline melanoma cell binding to HUVEC tended to be slightly higher than to HDMEC. In contrast, whereas phorbol 12-myristate 13-acetate (PMA) augmented melanoma cell adherence to HDMEC, PMA failed to increase adherence to HUVEC. The alterations in melanoma cell binding were induced only after pretreatment of endothelial and not melanoma cells with PMA. Studies of the expression of cell adhesion molecules (CAM) on HDMEC and HUVEC using enzyme-linked immunosorbent assay showed that vascular cell adhesion molecule 1 (VCAM-1) is not induced by PMA on HDMEC and intercellular adhesion molecule 1 (ICAM-1) is downregulated on HDMEC by PMA treatment. Endothelial leukocyte adhesion molecule 1 (ELAM-1) is induced by PMA, IL-1 alpha, or TNFalpha, but its expression does not correlate with increased melanoma cell binding MoAb recognizing VCAM-1-inhibited TNFalpha-induced increases in melanoma cell binding to HUVEC. However, anti-VCAM-1 antibody failed to clock melanoma cell binding to PMA or IL-1 alpha-stimulated HDMEC and only partially inhibited melanoma cell binding to TNF alpha-stimulated HDMEC. This study demonstrates that PMA and IL-1 alpha-induced increases in melanoma cell adherence to HDMEC are not mediated via known CAM, including ICAM-1, VCAM-1, or ELAM-1, and may be affected through microvessel-specific novel proteins not previously described on endothelial cells.

Antibodies, Monoclonal↗
PubMed1992

Expression and modulation of the vitronectin receptor on human dermal microvascular endothelial cells.

Microvascular endothelial cells express a variety of cell-surface integrins in vivo and in vitro with varying affinities for matrix proteins. The vitronectin receptor (VnR), a complex of the alpha v and beta 3 integrin chains, is capable of binding to a variety of matrix proteins that are deposited in injured tissues, including vitronectin, fibrinogen, and thrombin. Staining of frozen sections of human skin with antibodies recognizing the VnR and examination by immunofluorescence microscopy demonstrates staining in a vascular pattern suggesting in vivo expression of the vitronectin receptor on endothelial cells. Examination of pure cultures of human dermal microvascular endothelial cells (HDMEC) by flow-cytometric analysis and enzyme-linked immunosorbent assay confirmed that HDMEC also express cell surface VnR complex in vitro. Stimulation of human dermal microvascular endothelial cells in vitro with agents that stimulate protein kinase C resulted in dose- and time-dependent increases in expression of alpha v and beta 3 integrin chains. Additionally, stimulation with basic fibroblast growth factor induced similar increases, but stimulation with transforming growth factor-beta or interleukin-1 alpha failed to increase VnR expression. Increases in cell-surface VnR expression also correlated with an increased ability of microvascular endothelial cells to bind to vitronectin, but not fibronectin-coated surfaces. Although increases in cell-surface expression of beta 3 paralleled increases in expression of cell-surface alpha v, regulation of mRNA expression was distinct for each chain. These data suggests that microvascular endothelial cells express the VnR complex in vivo, that the cell-surface expression of this integrin on dermal microvascular endothelial cells can be regulated, and that this regulation may be important in cell adherence, cell migration, and wound healing.

Blotting, Northern↗
PubMed1992

Characterization of the oxidative stress initiated in cultured human keratinocytes by treatment with peroxides.

Cultured human keratinocytes were treated with H2O2, Fe++/Fe , H2O2 + Fe++/Fe , t-butylhydroperoxide (tBHP), or cumene hydroperoxide (CHP). Fe++ +/- Fe was without effect on cell viability. Neither CHP, tBHP, nor H2O2 at 200 microM led to alteration of trypan blue exclusion, but with 700 microM CHP or tBHP there was uptake of trypan blue after 20 min and lysis of cells beginning at 4 h of treatment. Lysis occurred even if the organic hydroperoxide was removed from the media after 1 h. Treatment with 700 microM H2O2 resulted in half of the cells becoming permeable to trypan blue by 60 min, but > 80% of the cells remained intact and functional, and eventually recovered their impermeability to trypan blue. No concentration of H2O2, tBHP, or CHP produced significant thiobarbituric acid (TBA)-reactive material, and Fe++/Fe , H2O2 + Fe++/Fe , and CHP + Fe++/Fe led to the formation of only small amounts of TBA-reactive material. This was attributed to a lack of polyunsaturated lipid in cells cultured in synthetic media. The activity of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is sensitive to oxidative damage and thus was used as an indicator of oxidative stress along with the ratio of reduced/oxidized glutathione (GSH/GSSG). Using these two criteria, we found that CHP or tBHP treatment led to an oxidative stress that was more protracted as compared with the effect of H2O2. The organic peroxides also led to depletion of total glutathione, an effect not found with H2O2. It was also found that H2O2 was more rapidly metabolized than the organic peroxides. In summary, cultured human keratinocytes treated with peroxides underwent a number of changes, which included inactivation of GAPDH, a decrease in the ratio GSH/GSSG, and a loss of trypan blue exclusion. However, as long as the duration of this oxidative stress was short, these changes were reversible and the cells survived. Prolonged oxidative stress led to irreversible damage and cell death. H2O2 was rapidly metabolized and relatively well tolerated by keratinocytes. On the other hand, organic hydroperoxides were metabolized more slowly and were lethal at sub-millimolar concentrations. The relative toxicity of organic hydroperoxides is hypothesized to be related to their non-polar nature.

Cell Survival↗
PubMed1992

An X-linked human collagen transgene escapes X inactivation in a subset of cells.

Transgenic mice carrying one complete copy of the human alpha 1(I) collagen gene on the X chromosome (HucII mice) were used to study the effect of X inactivation on transgene expression. By chromosomal in situ hybridization, the transgene was mapped to the D/E region close to the Xce locus, which is the controlling element. Quantitative RNA analyses indicated that transgene expression in homozygous and heterozygous females was about 125% and 62%, respectively, of the level found in hemizygous males. Also, females with Searle's translocation carrying the transgene on the inactive X chromosome (Xi) expressed about 18% transgene RNA when compared to hemizygous males. These results were consistent with the transgene being subject to but partially escaping from X inactivation. Two lines of evidence indicated that the transgene escaped X inactivation or was reactivated in a small subset of cells rather than being expressed at a lower level from the Xi in all cells, (i) None of nine single cell clones carrying the transgene on the Xi transcribed transgene RNA. In these clones the transgene was highly methylated in contrast to clones carrying the transgene on the Xa. (ii) In situ hybridization to RNA of cultured cells revealed that about 3% of uncloned cells with the transgene on the Xi expressed transgene RNA at a level comparable to that on the Xa. Our results indicate that the autosomal human collagen gene integrated on the mouse X chromosome is susceptible to X inactivation. Inactivation is, however, not complete as a subset of cells carrying the transgene on Xi expresses the transgene at a level comparable to that when carried on Xa.

Animals↗