Search PubMed⌕ Search

Biomedical subjects

H M Lee

Publications and source records attributed to H M Lee.

At least 163 records · Page 9Linked to original sources
PubMed1994

Monoclonal antibodies to mammalian D-type G1 cyclins.

D-type cyclins are necessary and rate-limiting for G1 progression during the mammalian cell cycle. Cyclins D1, D2, and D3 are encoded by distinct genes and are expressed in proliferating cells in a lineage-specific manner. Monoclonal antibodies (mAbs) generated to bacterially produced recombinant D-type cyclins were able to react with the native proteins expressed in mammalian cells. One mouse and three rat mAbs immunoprecipitated cyclin D1 from mouse macrophages. Only rat mAbs reacted with human cyclin D1 and cross-reacted with cyclin D2 expressed in proliferating T lymphocytes and human tumor cell lines. A single rat mAb to cyclin D2 exhibited a pattern of reactivity reciprocal to that of rat mAbs to D1. Three rat mAbs reacted specifically with mouse or human cyclin D3, but did not cross-react with cyclins D1 or D2 from either species. Representative mAbs were useful for immunoblotting and detected D-type cyclins coprecipitating in complexes recovered with antiserum to cyclin-dependent kinase-4 (CDK4). Because these mAbs detect D-type cyclins in the nuclei of fixed permeabilized cells, they should prove useful in documenting cyclin overexpression in those human tumors in which the genes are amplified or are targets of specific chromosomal rearrangements.

Animals↗
PubMed1994

Treating periodontal diseases by blocking tissue-destructive enzymes.

A new therapeutic approach involves the discovery by the "Stony Brook group," that tetracyclines, but not other antibiotics, can inhibit host-derived collagen-destructive enzymes. This newly discovered property of tetracyclines is unrelated to the antimicrobial activity of these drugs. Examples support the hypothesis that this unexpected property of tetracyclines provides a new approach to treating periodontal diseases as well as a variety of medical disorders.

Gingival Crevicular Fluid↗
PubMed1994

Mid-sagittal canal diameter and vertebral body/canal ratio of the cervical spine in Koreans.

In order to ascertain the normal values of the mid-sagittal canal diameter and the canal/body ratio of the cervical spine in Korean adults, ninety sets of cervical vertebral columns were examined. The average mid-sagittal canal diameters from C3 through C7 in the normal Korean are 13.2 +/- 1.3 millimeters in male and 13.1 +/- 2.6 millimeters in female. The normal average canal/body ratio of the cervical spine is 0.93 +/- 0.10 in male and 1.02 +/- 0.09 in female. The mid-sagittal canal diameter is largest in the White population and smallest in Asian, but there is no racial differences in the canal/body ratio, and the lower limit of normal canal/body ratio is 0.8 in Korean. The authors conclude that measurement of the canal/body ratio is more reliable than direct measuring of the mid-sagittal diameter of the cervical spinal canal in the diagnosis of cervical spinal stenosis or predicting the prognosis of cervical spinal cord injury.

Adult↗
PubMed1994

Induction with OKT3 and prostaglandin E1 in liver transplantation.

Forty-six consecutive adult patients underwent 51 orthotopic liver transplants in a prospective study to evaluate sequential induction with ORTHOCLONE OKT3 (muromonab-CD3), prostaglandin E1, cyclosporine, azathioprine, and methylprednisolone. Infection prophylaxis included preoperative bowel preparation and ganciclovir if cytomegalovirus was diagnosed in either donor or recipient. All rejection episodes were documented by liver biopsy before treatment. Seventy-four percent of patients evaluable beyond 1 year have had no rejection episodes. The retransplant rate was 10%, with a 4% primary nonfunction rate. There was no rejection of grafts that could not be retreated with OKT3. Forty-two percent (5 of 12) of rejection episodes responded to steroid recycling alone. The infection rates for all patients at 1 year were 54% bacterial, 17% fungal, and 22% viral. Three septic deaths were attributed to overimmunosuppression. Two-year patient and graft survival rates were 80% and 72%, respectively. This OKT3 induction protocol results in limited rejection episodes without increasing infections, yielding an acceptably low rate of graft loss.

Adult↗
PubMed1993

Differential activation of CD8+ T cells by transforming growth factor-beta 1.

Transforming growth factor-beta (TGF-beta) is a highly conserved multifunctional factor that broadly regulates cell growth and differentiation, and exhibits diverse regulatory roles in the immune system. In contrast to other studies describing TGF-beta as a potent inhibitor of lymphocyte growth, we have shown previously that TGF-beta 1 can also costimulate proliferation of murine splenic T cells activated by immobilized anti-CD3 antibody. In the present studies, we further investigate the subsets of T cells that are responsive to TGF-beta 1 costimulation. T cells were isolated into CD45RBhi/lo or CD4+/8+ populations, and their responses to TGF-beta 1 were examined. Sorted CD45RBhi cells were highly responsive to TGF-beta 1 costimulation, and proliferated to a level similar to that of unsorted T cells in response to TGF-beta 1. TGF-beta 1 also costimulated proliferation in the CD45RBlo population that was distinguished by low response and delayed kinetics. In contrast, sorted CD4+ and CD8+ T cells showed a striking differential response. Anti-CD3-stimulated proliferation of sorted CD8+ or CD4- T cells was substantially enhanced by TGF-beta 1, whereas sorted CD4+ or CD8- T cells were unresponsive. TGF-beta 1 also down-regulated CD45RB and increased CD44 expression on responsive CD8+ and CD45RBhi T cells, thereby leading to a population of T cells enriched in mature phenotype. Generation of anti-CD3-redirected lytic activity by these TGF-beta 1-costimulated CD8+ cells was strongly suppressed. However, these CD8+ T cells exhibited cytotoxic activity after restimulation in the absence of TGF-beta. TGF-beta 1 precultured CD8+ T cells also had heightened IL-2 and IFN-gamma secretion upon restimulation in comparison to cells activated initially without TGF-beta. CD8+ T cells precultured with anti-CD3 and TGF-beta remained responsive to growth enhancement by TGF-beta, although re-exposure to TGF-beta depressed other functions of these cells. Thus, TGF-beta 1 demonstrates important costimulatory roles in both growth and maturation of CD8+ T cells.

Animals↗
PubMed1993

Reactive oxygen species activate and tetracyclines inhibit rat osteoblast collagenase.

Recent studies have demonstrated that tetracyclines (TCs) scavenge reactive oxygen species (ROS). Hypochlorous acid (HOCl), an ROS produced by neutrophils, has been shown to activate neutrophil procollagenase. The objective of the present study was to determine whether (1) HOCl also activated osteoblast procollagenase and (2) TCs inhibited this enzyme in the presence of HOCl. HOCl (5 microM) activated the proenzyme approximately sixfold (P < 0.01) from the medium of PTH-treated UMR-106-01 osteoblastic osteosarcoma cells as determined by functional collagenase assay (3H-methyl-labeled collagen substrate). Doxycycline (50-400 microM) and chemically modified tetracycline, CMT-1 (100-400 microM), significantly inhibited collagenase activity 50-90% and 40-80%, respectively, in the presence of 5 microM HOCl. Concentrations of 6-25 microM doxycycline and 10-50 microM CMT-1 had no significant effect. Furthermore, an excess concentration of cation (50 mM CaCl2 or 50 microM ZnCl2) added to the incubation mixtures containing either doxycycline or CMT-1 did not restore collagenase activity, as demonstrated by SDS-PAGE-fluorography. These data suggested that TCs reduced available HOCl and thus prevented the hypochlorous acid conversion of the osteoblast proenzyme to active collagenase. TCs may have therapeutic potential in the treatment of periodontitis and other diseases by several mechanisms that inhibit pathologic collagen breakdown.

Animals↗
PubMed1993

Doxycycline protects serum alpha-1-antitrypsin from human neutrophil collagenase.

Interstitial collagenases, members of the matrix metalloproteinase family, are key initiators of collagen destruction during various disorders such as rheumatoid arthritis. Recently interstitial collagenases were found to efficiently degrade an additional non-collagenous substrate, the serum alpha-1-antitrypsin (AAT also called alpha-1-proteinase inhibitor or serpin). Serpins are major endogenous inhibitors of serine proteinases, particularly neutrophil elastase. Of relevance to neutrophil-mediated collagen degradation, the tetracycline family of antibiotics are now known to inhibit inhibit mammalian collagenases by a mechanism unrelated to their antimicrobial activity. This study identifies an additional mechanism by which tetracyclines may retard tissue breakdown during inflammatory diseases. Doxycycline, added to the reaction mixture as in concentrations as low as 10 microM, which correspond to levels of the drug readily achieved in vivo, produced detectable inhibition of serpinase activity of neutrophil collagenase, although levels of 50-100 microM or greater were required to reduce AAT degradation more than 75%. The concentration of doxycycline to inhibit 50% (IC50 of serpinase activity) of AAT degradation by neutrophil collagenase was found to approximate 20 microM, a value similar to the IC50 for doxycycline required to inhibit collagen degradation by neutrophil collagenase. Doxycycline was also found to inhibit at cell level neutrophil-mediated degradation of AAT. The protection of bodies' AAT-shield from serpinolytic activity of collagenase would result in inhibition of serine proteinases such as neutrophil elastase. Tetracyclines may thus protect matrix constituents from a wider spectrum of neutral proteases than previously recognized, not just from the matrix metalloproteinases collagenase and gelatinase.

Collagenases↗
PubMed1993

Study on the purification of growth hormone-like substance from pituitaries of the snake Ptyas mucosa.

Extract from the snake (Ptyas mucosa) pituitaries was capable of inhibiting the binding of 125I-labelled bovine growth hormone to female rat liver membranes. The growth hormone-like substance was not adsorbed on Concanavalin A-Sepharose nor DEAE-cellulose, but could be purified by gel filtration on Sephadex G-50. It possessed a molecular weight of about 19,000 as judged by SDS-polyacrylamide gel electrophoresis. The iodinated snake growth hormone-like substance bound to membranes prepared from female rat and pregnant rabbit livers. The binding could be inhibited by unlabelled snake growth hormone-like substance as well as by bovine growth hormone.

Animals↗
PubMed1993

Doxycycline in the protection of serum alpha-1-antitrypsin from human neutrophil collagenase and gelatinase.

The concentration of doxycycline required to inhibit 50% (50% inhibitory concentration for serpinase activity) of alpha-1-antitrypsin degradation by purified neutrophil collagenase was found to be approximately 20 microM, a value similar to the 50% inhibitory concentration of doxycycline required to inhibit collagen degradation by neutrophil collagenase. Doxycycline also efficiently inhibited phorbol myristate acetate-triggered neutrophil-mediated degradation of alpha-1-antitrypsin. This suggests that doxycycline can protect alpha-1-antitrypsin from collagenase and gelatinase in the presence of other proteases and biologically active molecules that are released by triggered neutrophils. The protection of a body's alpha-1-antitrypsin shield from serpinolytic activity of collagenase and matrix metallproteinases can result in inhibition of serine proteases such as neutrophil elastase. Tetracyclines may thus protect matrix constituents from a wider spectrum of neutral proteases than previously recognized, not just from the matrix metalloproteinases collagenase and gelatinase.

Collagenases↗
PubMed1993

Effectiveness of bleomycin in comparison to tetracycline as pleural sclerosing agent in rabbits.

The two agents most commonly used for producing a pleurodesis are tetracycline and bleomycin. Tetracycline is no longer available due to more stringent requirements on the manufacturing process. The objective of this project was to determine whether bleomycin is an effective sclerosant in an experimental model in rabbits. The following medications were instilled intrapleurally in anesthetized male rabbits: tetracycline, 35 mg/kg, or bleomycin, 1.5 or 3.0 IU/kg diluted to a total volume of 1 ml with bacteriostatic saline solution. Twenty-eight days after the instillation, the animals were killed, and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The intrapleural injection of bleomycin was ineffective in creating pleural fibrosis, either grossly or microscopically. The mean degree of gross pleurodesis in the six rabbits who received tetracycline was 2.7 +/- 1.5 (scale 0 to 4), while that in the rabbits who received the highest dose of bleomycin was 0.0 +/- 0.0. Based on this study, we recommend that bleomycin not be used as a pleural sclerosant in patients with nonneoplastic pleural disease, eg, those with pneumothorax, congestive heart failure or cirrhosis, and pleural effusion.

Analysis of Variance↗
PubMed1992

pp59fyn mutant mice display differential signaling in thymocytes and peripheral T cells.

We have generated mutant mice that do not express pp59fyn, a nonreceptor protein tyrosine kinase related to pp60src, by homologous recombination in embryonic stem cells. fyn- mice did not display an overt phenotype. Because fyn is associated with the T cell receptor (TCR), thymocyte and T cell signaling was analyzed in the mutant background. Cross-linking of TCR-CD3 in thymocytes led to markedly reduced calcium fluxes and abrogated proliferation, whereas mature splenic T cells retained largely normal proliferation despite depressed calcium movements and IL-2 production. Similarly, proliferation induced by Thy-1 cross-linking was reduced in thymocytes but not in splenic T cells. fyn- thymocytes were impaired at a late stage of maturation and showed limited clonal deletion to the Mls-1a self-super-antigen but not to staphylococcal enterotoxin A. These results implicate fyn as a critical component in TCR signaling in thymocytes and, potentially, in the process that determines T cell repertoire in the adult mouse.

Animals↗
PubMed1992

Magnesium-dependent inhibition of agonist-stimulated phosphoinositide breakdown in rat cortical slices by excitatory amino acids.

The excitatory amino acid agonists kainate, N-methyl-D-aspartate (NMDA), and quisqualate inhibited ligand-stimulated phosphoinositide hydrolysis in rat cortical slices. The NMDA channel blocker MK-801 antagonized the inhibition by NMDA but had no effect on the inhibition due to kainate or quisqualate. The antagonist 6-cyano-7-nitroquinoxaline-2,3-dione blocked the effects of quisqualate and kainate but not the effect of NMDA. These data indicate that activation of the NMDA, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, and kainate types of ionotropic receptors has the same effect. In membranes prepared from cortical slices, there was no inhibition of carbachol-stimulated phosphoinositidase C activity by excitatory amino acids, suggesting that excitatory amino acids indirectly affect carbachol-stimulated phosphoinositide hydrolysis. The inhibition by excitatory amino acids of carbachol-stimulated phosphoinositide breakdown was dependent on extracellular Mg2+ and was abolished by procedures that increase intracellular Ca2+. Veratridine inhibition of carbachol-stimulated phosphoinositide hydrolysis was reversed by ouabain but not by other procedures that increase intracellular Ca2+. In contrast to excitatory amino acids, veratridine potentiated carbachol-stimulated phosphoinositide breakdown in the presence of 10 mM extracellular Mg2+. These data suggest that excitatory amino acids inhibit carbachol-stimulated phosphoinositide breakdown in rat cortex by lowering intracellular Ca2+ through a mechanism dependent on extracellular Mg2+.

Amino Acids↗
PubMed1992

Specificity of the anticollagenase action of tetracyclines: relevance to their anti-inflammatory potential.

The concentrations of doxycycline and 4-de-dimethylaminotetracycline required to inhibit 50% of collagenase activity were found to be 15 to 30 microM for human neutrophil and gingival crevicular fluid collagenases. Fibroblast collagenase was relatively resistant to inhibition by tetracyclines; the 50% inhibitory concentrations of doxycycline and 4-de-dimethylaminotetracycline were 280 and 510 microM, respectively.

Anti-Inflammatory Agents↗
PubMed1992

Effect of porcine bone morphogenetic protein on healing of bone defect in the rabbit radius.

Segmental long bone defects due to infection or trauma is a difficult problem to manage in patients. We studied the effect of porcine bone morphogenetic protein (pBMP) on healing of defects in the rabbit radius. Porcine BMP was separated and purified from the tibia and femur of pigs by repeated solubilization and precipitation of the protein with different concentrations of urea and GuHCl. The osteoinductive activity of pBMP was confirmed by bioassay using No. 615 mice. In rabbits, about a 15 mm length of radii were removed and 20 mg of pBMP was implanted in the defected area with fibrin sealant (FS), while only FS was implanted in controls. Union of the affected area was observed in 6 weeks in the experimental side. There was no definite evidence of bone bridging across the affected area in the controls. This suggests that pBMP has a bone forming activity in other species and the clinical use of pBMP in treating patients with segmental bone defects is promising.

Animals↗
PubMed1992

Parathyroid hormone regulation of matrix degrading enzymes in rat osteoblastic osteosarcoma 17/2.8 cells.

The present study was designed to further understand the role of PTH on the secretion of the neutral metalloproteinases, collagenase and gelatinase, from the rat osteosarcoma clonal cell line, ROS 17/2.8. Semiconfluent cells were treated with bovine parathyroid hormone, b-PTH-(1-34) at 100 nM-0.01 nM for 24-96 hours and pooled, concentrated media were analyzed by functional assay for collagenase (3H-methyl collagen) and gelatinase (3H-methyl gelatin). Collagenase activity significantly decreased (P less than 0.01) in the PTH conditioned media in a dose-dependent manner before (98-64%) and after (91-39%) reduction and alkylation. SDS-PAGE and fluorography apparently showed the most degradation to alpha A chains in collagen with controls, whereas this substrate remained intact with PTH (100 nM). PTH (100 nM) media also showed neutral gelatinase activity approximately 2% compared to control before and after reduction and alkylation (P less than 0.01). Significant amounts of an inhibitor to collagenase and gelatinase might have been secreted at 1 nM and 0.01 nM PTH, since collagenase and gelatinase activities were greater after reduction and alkylation. Reduction and alkylation likely destroyed these significant amounts of inhibitor. Polymorphonuclear leukocyte collagenase activity was also inhibited 80% by PTH conditioned media, but not by control. However, upon reduction and alkylation which destroyed inhibitor, the PTH treated media showed only a 14% inhibition against polymorphonuclear leukocyte collagenase (P less than 0.01). PTH appeared to downregulate neutral metalloproteinase activities through its effects on an inhibitor. This downregulation may represent a specific phenotypic response to PTH in ROS 17/2.8 cells.

Alkylation↗
PubMed1991

Co-stimulation of T cell proliferation by transforming growth factor-beta 1.

Transforming growth factor-beta (TGF-beta) exhibits diverse regulatory roles in the immune system and has been described as a potent inhibitor of lymphocyte and hemopoietic progenitor cell growth. The present studies investigated the effects of TGF-beta 1 on murine T cell proliferation triggered through the T cell receptor/CD3 complex. In contrast to previously reported T cell growth inhibition, TGF-beta 1 costimulated splenic T cell proliferation in the presence of immobilized anti-CD3 antibody 2C11, with maximal effect at anti-CD3 concentration of 50 micrograms/ml. Although TGF-beta 1 induced a modest increase in IL-2R display, TGF-beta 1 co-stimulated proliferation was largely independent of IL-2 and/or IL-4. Anti-IL-2 and/or anti-IL-4 antibody did not significantly block the TGF-beta 1 co-stimulated T cell growth, and no IL-2 or IL-4 bioactivity was detected in TGF-beta 1 co-stimulated cultures. TGF-beta 1 did not enhance IL-2 mRNA expression beyond control levels. However, TGF-beta 1 co-stimulation caused an accelerated evolution of a memory or mature T cell population phenotype. Both CD4+ and CD8+ T cell subsets were significantly enriched for cells of the mature CD45RBloPgp-1hi phenotype, in comparison with T cells stimulated by anti-CD3 alone or with PMA, and CD8+ T cells predominated. These results thus provide initial evidence that TGF-beta 1 is capable of bifunctional T cell growth regulation, which occurs largely via an IL-2- and IL-4-independent pathway.

Animals↗
PubMed1991

Immunocytochemical localization of octopamine in the central nervous system of Limulus polyphemus: a light and electron microscopic study.

We have determined the distribution and localization of the monoamine octopamine in the prosomal central nervous system of the horseshoe crab, Limulus polyphemus, by light and electron microscopic immunocytochemistry. Sixteen discrete clusters of octopamine-like immunoreactive neurons are situated bilaterally in the tritocerebrum and circumesophageal ring of fused thoracic ganglia. Two pairs of anterior clusters are located laterally in the cheliceral and first pedal ganglia; the remaining six pairs of clusters are located ventromedially in the second through fifth pedal ganglia, chilarial ganglia, and opercular ganglia. The immunoreactive somata range from about 40 to 100 microns in diameter and occur in clusters of 12-24 cells. There is extensive distribution of octopamine-immunoreactive nerve fibers in Limulus; dense fiber tracts course anteroposteriorly through the central nervous system, and most neuropil regions are innervated by immunoreactive processes and terminals. This wide distribution of octopamine-like immunoreactivity provides an anatomical basis for the several effects of octopamine in Limulus. We determined the subcellular localization of octopamine by postembedding immunoelectron microscopy. The immunogold-labelled terminals are morphologically unique; they contain large, distinctively shaped dense-core granules, typically cylindrical with a prominent indentation in one end. These large granules are 100-150 nm in diameter and range from 150-400 nm in length. The dense labelling of these unusual granules with immunogold particles indicates that octopamine is sequestered in or associated with the granules.

Animals↗