201
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Tao Y, Dai S, Jin S, Liao W, Chen J, Liao H, Fan J. [Clinical application of rhombotrapezious island musculocutaneous flap for skull base and/or craniomaxillary operation with malignant tumor]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1994; 25:203-6. [PMID: 7806201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Regional pedicled musculocutaneous flaps are the mainstay of the head and neck reconstruction. They provide a rapid, highly reliable and single-staged technique that is applicable in most cases. The rhombotrapezious island musculocutaneous flap is valuable in the base and craniomaxilloface reconstruction. In this study we updated our experience with the rhombotrapezious island musculocutaneous flap (RTIMF) in 6 cases from 1989 to 1993. Dissections were performed on 9 cadavers, 4 preserved and 5 fresh, yielding 18 pairs or dorsal scapular and transverse cervical artery for evaluation. In the five fresh cadavers, the arteries were selectively cannulated and injected with colored latex. 67% with dorsal scapular and transverse cervical artery commonly arose from the thyro-cervical trunk. 33% with the dorsal scapular artery directly arose from the second part of the subclavian artery. In the period of 1989-1993, 6 rhombotrapezious island musculocutaneous flaps with vascularized pedicle were used for immediate repair in the skull base or craniomaxillary cancer operations. There was no complication of the flaps. Donor site complications were relatively minor. The disturbance in shoulder function was well tolerated. We advocated the incorporation of both the greater and lesser rhomboid muscle to form the compound rhombotrapezious flaps to enhance the vascular supply to the overlying skin. The major advantage of the RTIMF are that it provides a long paddle of thin pliant, hairless skin and muscle that can be rotated as far as the craniomaxilloface and scalp in a single stage. It offers the longest arc of rotation and thus the greatest versatility for the skull base or craniomaxillary reconstruction.
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202
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Fan HZ, Liu YX, Zhang J, Liao W, Yu J. [Comparison of protein assays for ejiao]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1994; 19:224-7, 256. [PMID: 7945855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Ejiao exhibits identical spectral characteristics with those of reference gelatin in Murphy's UV spectrophotometry and color-yielding reactions performed according to Gornall's biuret and Lowry's Folin phenol procedures respectively. Results of protein assays of Ejiao measured by above-mentioned photometric methods were in good approximation to each other using gelatin as standard and comparable with that of Kjeldahl nitrogen determination.
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203
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Liao W, Florén CH. Enhancement by lipoprotein-free plasma of the inhibitory effect of endotoxin on endocytotic catabolism of low density lipoproteins in Hep G2 cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 220:349-57. [PMID: 8125091 DOI: 10.1111/j.1432-1033.1994.tb18631.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We previously showed that the presence of microgram levels of endotoxin inhibited low-density lipoprotein (LDL) uptake and degradation in Hep G2 cells. We also showed that both the polysaccharide and lipid A parts of endotoxins are needed for the inhibitory effects of endotoxins on cellular LDL uptake. The current study was carried out by inclusion of lipoprotein-free plasma (LFP) in tissue culture medium to observe the modulatory influence of non-lipoprotein factor(s) on endotoxin-induced inhibition of endocytotic catabolism of LDL in Hep G2 cells. We found that LFP dramatically promotes the inhibitory effect of endotoxins with a complete polysaccharide, but has no influence on the effect of the Re mutant endotoxin (from S. minnesota Re595), which lacks polysaccharide. By using gel-filtration chromatography, agarose electrophoresis and agarose isoelectric focusing, we further showed that in the presence of LFP, both the endotoxins with a complete polysaccharide and the Re mutant endotoxin complex with and anionize LDL, while in the absence of LFP, these endotoxins poorly interact with LDL. Thus, endotoxin inhibits cellular endocytotic catabolism of LDL by forming LDL-endotoxin complexes, and LFP enhances endotoxin-induced inhibition of endocytotic catabolism of LDL by promoting the interaction between endotoxin and LDL. In addition, our finding that the Re mutant endotoxin also interacts with LDL to form LDL-endotoxin complexes, but has no significant effect on LDL uptake and degradation, further supports the notion that both the polysaccharide and lipid A parts of endotoxins are needed for the inhibitory effects of endotoxins on cellular LDL uptake.
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204
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Xu CB, Stavenow L, Liao W, Erlinge D, Edvinsson L. Interactions between cultured bovine arterial endothelial and smooth muscle cells: studies on uptake and degradation of low density lipoproteins by smooth muscle cells. PHARMACOLOGY & TOXICOLOGY 1993; 73:269-73. [PMID: 8115309 DOI: 10.1111/j.1600-0773.1993.tb00583.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study was designed to investigate the effects of substances released from non-injured and injured bovine arterial endothelial cells on 125I-low density lipoprotein uptake and degradation by smooth muscle cells in culture. It was demonstrated that endothelial cell-released non-dialysable (molecular weight cut off 12-14000) substances significantly stimulated 125I-low density lipoprotein uptake and degradation by smooth muscle cells. Endothelial cell-released dialysable substances and endothelin-1 did not cause this stimulation. The increase in 125I-low density lipoprotein uptake and degradation by smooth muscle cells could be dissociated from cell proliferation. However, in endothelial cell-smooth muscle cell co-culture 125I-low density lipoprotein uptake and degradation by smooth muscle cells were not stimulated. Injury to endothelial cells by lipid-soluble smoke particles or ultraviolet light, which reduced total cellular protein by 15-25%, enhanced the endothelial cell release of the substances stimulating 125I-low density lipoprotein uptake. The results are discussed in relation to atherogenesis.
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MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/metabolism
- Azepines/pharmacology
- Blood Proteins/pharmacology
- Cattle
- Cells, Cultured
- Endothelin Receptor Antagonists
- Endothelins/pharmacology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- Humans
- Indoles/pharmacology
- Lipoproteins, LDL/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Radiation Injuries, Experimental
- Smoke
- Thymidine/pharmacology
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205
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Sun N, Wen Y, Yan S, Sun Z, Zhou R, Liao W. [A study on the transcriptional expression of oncogenes in human primary brain tumors]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1993; 24:135-138. [PMID: 8244289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The c-myc, L-myc, N-myc, Ha-ras, c-fos, and v-erbB oncogenes were used as probes to detect the total RNA of 5 cases of normal human brain tissues and 29 cases of brain tumor tissues by RNA dot hybridization analysis. The results showed that the increasing expressions of cerbB and c-fos were the highest, being 88.2% and 82.4%, respectively, the next was c-myc with an increased expression of 46.1%; the increasing expressions of L-myc (29.3%) and N-myc (31.6%) were observed in a few samples only. There was no significant difference of Ha-ras gene expression between normal brain and brain tumor. In addition, we observed the increasing expression of more than one oncogene in one sample. These results suggest that c-erbB and c-fos oncogenes may play an important role in the pathogenesis of human primary brain tumors, and that multiple genetic changes are implicated in genesis of human brain tumors.
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206
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Liao W, Florén CH. Polymyxin B complexes with and cationizes low density lipoproteins. The cause of polymyxin B-induced enhancement of endocytotic catabolism of low density lipoproteins. Biochem Pharmacol 1993; 45:1835-43. [PMID: 8494542 DOI: 10.1016/0006-2952(93)90441-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We previously reported that polymyxin B (PMB) enhances cellular catabolism of low density lipoproteins (LDLs) through a non-LDL receptor-mediated endocytotic pathway. These data were obtained mainly by using Hep G2 cells, a well differentiated human hepatoma cell line. In the current study, we explore the mechanisms of PMB-mediated endocytotic catabolism of LDL. We found that PMB enhanced LDL catabolism also in homozygous familial hypercholesterolemia fibroblasts, thereby establishing that PMB-mediated cellular catabolism of LDL does not involve LDL receptors. By using [14C]sucrose, and ligands for the asialoglycoprotein (ASGP) receptors, possibilities were excluded that PMB enhances cellular endocytosis of LDL, by inducing a general increase of cellular pinocytic activity or by causing endocytosis of LDL via the ASGP receptors in Hep G2 cells. We further show, by using polymyxin B coupled Sepharose 4B (PMB-Sepharose 4B) beads, that PMB binds to LDL to form a complex. This binding was tight, and changes in pH and salt concentrations had no significant effect on the binding, but unlabelled LDL competed with 125I-LDL to bind to PMB-Sepharose 4B. Urea and endotoxins decreased this binding, suggesting that PMB binds to LDL at least partially through hydrophobic interactions. Agarose gel electrophoresis of PMB-LDL indicates that PMB cationizes LDL. In conclusion, PMB binds to LDL to form a PMB-LDL complex presumably through interactions between lipid groups. This endows LDL with positive charges, which enhances LDL binding to negatively charged cell membranes, and such bound LDL is rapidly internalized through absorptive endocytosis.
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207
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Sista ND, Pagano JS, Liao W, Kenney S. Retinoic acid is a negative regulator of the Epstein-Barr virus protein (BZLF1) that mediates disruption of latent infection. Proc Natl Acad Sci U S A 1993; 90:3894-8. [PMID: 8387200 PMCID: PMC46412 DOI: 10.1073/pnas.90.9.3894] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Disruption of latent Epstein-Barr virus (EBV) infection is induced by the key immediate-early protein BZLF1 (or Z, a member of the basic leucine-zipper family), which transactivates the viral early promoters. Viral reactivation is marked by renewed synthesis of early gene products such as EBV early antigen-diffuse (EA-D). Retinoic acid has been previously shown to inhibit reactivation of EBV infection. Retinoic acid responsive receptors are known to act as positively regulating transcription factors but can also negatively regulate AP-1 responsive genes. Here we demonstrate that the retinoic acid receptor alpha (RAR alpha) and retinoid X receptor alpha (RXR alpha) inhibit the ability of the Z protein to transactivate the viral early promoter BMRF1, which directs transcription of EA-D. Z can also reciprocally inhibit RAR alpha- and RXR alpha-induced activation of an autoregulated cellular promoter for the RAR beta gene (BRE) through a non-DNA binding mechanism. RXR alpha inhibits Z from binding to the AP-1 motif in the BMRF1 promoter and, reciprocally, Z inhibits RAR alpha from binding to its retinoic acid response element in the BRE promoter. Furthermore, a glutathione-S-transferase-RXR alpha fusion protein can interact directly with the Z protein. These results suggest that a direct protein-protein interaction between Z (the viral protein) and RAR alpha and RXR alpha (cellular proteins) can modulate the reactivation of latent EBV infection.
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MESH Headings
- Animals
- Base Sequence
- Carrier Proteins/antagonists & inhibitors
- Carrier Proteins/metabolism
- Cells, Cultured
- Chloramphenicol O-Acetyltransferase/genetics
- Chloramphenicol O-Acetyltransferase/metabolism
- DNA, Viral/genetics
- DNA, Viral/metabolism
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Genes, Viral
- Herpesvirus 4, Human/drug effects
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/physiology
- Leucine Zippers/genetics
- Leucine Zippers/physiology
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Oligodeoxyribonucleotides/chemical synthesis
- Oligodeoxyribonucleotides/metabolism
- Promoter Regions, Genetic
- Receptors, Cell Surface/antagonists & inhibitors
- Receptors, Cell Surface/metabolism
- Receptors, Retinoic Acid
- Recombinant Fusion Proteins/metabolism
- Retinoid X Receptors
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription Factors
- Transfection
- Tretinoin/pharmacology
- Viral Proteins/genetics
- Virus Activation/drug effects
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208
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Liao W, Florén CH. Tumor necrosis factor up-regulates expression of low-density lipoprotein receptors on HepG2 cells. Hepatology 1993; 17:898-907. [PMID: 8387950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Tumor necrosis factor mediates most biological activities of endotoxin and also, in part, mediates endotoxin-induced disturbances in lipid metabolism. In this study, the effect of tumor necrosis factor on low-density lipoprotein receptor activity was investigated in cells of HepG2, a well-differentiated human hepatoma cell line. Pretreatment of the cells with tumor necrosis factor leads to enhanced binding, uptake and degradation of 125I-labeled low-density lipoprotein. This effect of tumor necrosis factor was dose and time dependent. Tumor necrosis factor-stimulated enhancement of low-density lipoprotein binding occurred at all stages of cell growth. However, addition of an excess of unlabeled low-density lipoprotein, to down-regulate low-density lipoprotein receptors before exposure to tumor necrosis factor of the cells, completely abolished the effects of tumor necrosis factor. Competition experiments using unlabeled low-density lipoprotein and blockage experiments with a monoclonal low-density lipoprotein receptor antibody showed that tumor necrosis factor-stimulated low-density lipoprotein binding takes place through stimulation of low-density lipoprotein receptors. Comparison of the kinetics of specific low-density lipoprotein binding in the unstimulated cells and in the tumor necrosis factor-stimulated cells indicated that tumor necrosis factor caused a 30% increase in maximum velocity with no significant change in Michaelis constant, suggesting that tumor necrosis factor increases the number of low-density lipoprotein receptors on the cells rather than changing binding affinity. Preincubation of the cells with cycloheximide or actinomycin D totally abolished the up-regulatory effect of tumor necrosis factor on low-density lipoprotein receptors. Tumor necrosis factor did not stimulate proliferation of HepG2 cells, as judged by cell protein determination or by [3H]thymidine incorporation. In conclusion, this study suggests that tumor necrosis factor up-regulates expression of low-density lipoprotein receptors on HepG2 cells by stimulation of de novo synthesis of receptors, independent of cell growth.
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209
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210
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Liao W, Florén CH. Hyperlipidemic response to endotoxin--a part of the host-defence mechanism. SCANDINAVIAN JOURNAL OF INFECTIOUS DISEASES 1993; 25:675-82. [PMID: 8052806 DOI: 10.3109/00365549309008562] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Endotoxin administration into experimental animals leads to an acute hyperlipidemic response. In addition, lipoproteins can inhibit various biological activities of endotoxin both in vitro and in vivo. The endotoxin-binding and endotoxin-inactivating abilities of lipoproteins, as well as the plasma levels of lipoproteins, are thus increased following endotoxin administration. The endotoxin-induced hyperlipoproteinemia may not only represent the consequence of endotoxemia, but may also be a physiological defence mechanism whereby the body attempts to combat the toxic effects of circulating endotoxin. This minireview discusses the interaction between lipoproteins and endotoxin, and the role of this acute hyperlipidemic response to endotoxin in the context of the host-defence mechanism.
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211
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Li W, Li Z, Liao W, Feng XD. Chemical modification of biopolymers--mechanism of model graft copolymerization of chitosan. JOURNAL OF BIOMATERIALS SCIENCE. POLYMER EDITION 1993; 4:557-66. [PMID: 8241070 DOI: 10.1163/156856293x00203] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mechanism of graft copolymerization of vinyl monomers onto chitosan initiated by Ce(IV) ion, one of the important ways of chemical modification of chitosan, has been investigated by means of kinetics measurement and polymer chain structure analysis. It is found that when Ce(IV) ions reacts with adjacent hydroxylamine structure in chitosan, a chelate complex is first formed and then it disproportionates to radical for initiation of graft copolymerization. There exist two ways for such initiation depending upon the reaction temperature. For a reaction temperature lower than 40 degrees C, a -CHO group and a -C = NH group are introduced, and the aldehyde group reacts with Ce(IV) ions to form an acyl radical which initiates a graft polymer chain in this saccharide unit. For temperatures higher than 90 degrees C, the -C = NH group hydrolyzes to form an amine and an aldehyde group which also reacts with Ce(IV) ions. In this case there should be two aldehyde groups, i.e. two initiation sites, in one adjacent hydroxyl-amine structure. That means that the initial radical in the chitosan/Ce(IV) system is similar to that in the cellulose/Ce(IV) one, but the former usually gives a lower grafting reactivity than the latter due to the higher stability of the chelate.
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212
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Liao W, Lindgren S, Lindhagen T, Starck M, Florén CH. Plasma endotoxin in patients with quiescent Crohn's disease. J Intern Med 1992; 232:371. [PMID: 1402642 DOI: 10.1111/j.1365-2796.1992.tb00601.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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213
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Liao W, Jin XY, Wang BH, Cui XS, Wang JL, Zhang J, Zhou TJ. Impaired blood superoxide dismutase in the traumatic paraplegic patients. Acta Neurol Scand 1992; 86:329-31. [PMID: 1414256 DOI: 10.1111/j.1600-0404.1992.tb05095.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Blood superoxide dismutase (SOD) activity and blood copper, zinc-superoxide dismutase (Cu.Zn-SOD) content were measured by luminol chemiluminescence assay and by single radial immunodiffusion assay, respectively, in 50 patients with paraplegia due to traumatic injury to the spinal cord by the Tangshan Earthquake on July 28, 1976, compared with 20 age-matched healthy subjects. We found that blood SOD activity and blood Cu.Zn-SOD content in the paraplegic patients were significantly lower than those in healthy subjects (p < 0.01). In healthy subjects, blood Cu.Zn-SOD fully expressed the enzymatic activity, whereas only 77% of blood Cu.Zn-SOD in the paraplegic patients expressed the enzymatic activity, indicating that in the patients, part of blood Cu.Zn-SOD protein is in a state without function. Also the serum lipid peroxide level in the paraplegic patients was higher than that in healthy subjects (p < 0.05). These findings suggest decreased endogenous blood protection against oxygen derived free radicals in these paraplegic patients.
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214
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Abstract
The effects of endotoxins on the uptake and degradation of low-density lipoproteins in Hep G2, a well-differentiated human hepatoma cell line, were studied. The results showed that incubation of Hep G2 cells with 125I-labeled low-density lipoprotein in the presence of endotoxins caused decreased uptake and degradation of 125I-labeled low-density lipoprotein. The inhibitory effects of endotoxins on the uptake and degradation of 125I-labeled low-density lipoprotein were dose and time dependent. With a monoclonal low-density lipoprotein receptor antibody, it was found that endotoxins interfered with both low-density lipoprotein receptor-mediated and non-low-density lipoprotein receptor-mediated uptake. If, however, the cells were pretreated with endotoxins for 1 or 24 hr and then incubated with new medium without endotoxins, no inhibitory effect on the subsequent uptake and degradation of 125I-labeled low-density lipoprotein occurred. Endotoxins had no toxic effects on Hep G2 cells as judged by [3H]thymidine incorporation and by determination of cell growth. Also, endotoxins did not under our experimental conditions induce oxidative modification of low-density lipoprotein. Furthermore, reisolated low-density lipoprotein that had previously been incubated with endotoxin was catabolized to a lower extent by Hep G2 cells than was control low-density lipoprotein. We speculate that the inhibitory effect of endotoxins on cellular low-density lipoprotein catabolism is due to the formation of endotoxin-low-density lipoprotein complexes, which interfere with the binding of low-density lipoprotein to the cell surface.
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215
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Yan J, Chen H, Liao W, Lu S. Cardiovascular effects of thyrotropin-releasing hormone in normotensive and hypotensive rats: role of rostral ventrolateral medulla. CIRCULATORY SHOCK 1992; 37:253-61. [PMID: 1423917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
To ascertain the central mechanism of the effects of thyrotropin-releasing hormone (TRH) on the cardiovascular system, we evaluated the effects of this neuropeptide on unit fires in the rostral ventro-lateral medulla (RVL), mean arterial pressure (MAP), and heart rate (HR) in normotensive and hypotensive rats. Intracerebroventricular injection (i.c.v.) of 10 micrograms TRH significantly increased MAP and HR in both normotensive and hypotensive rats. No similar effects were observed after saline injection. If electrolytic lesions of bilateral RVL were made, the cardiovascular effects of TRH i.c.v. failed to occur. TRH i.c.v. markedly increased the firing frequency of most units in the RVL. In particular, TRH i.c.v. increased the firing frequency of most units excitatory to a fall in MAP and decreased the firing frequency of most units inhibitory to a fall in MAP in normotensive rats. Moreover, a drop of MAP as low as 40 mmHg for 10 min resulted in an increase of the firing frequency of most units. The effect of TRH i.c.v. on the RVL units in the hypotensive rats was similar to that in the normotensive rats. Our findings suggest that TRH is able to intensify the cardiovascular activities and the RVL plays a key role in the effects of TRH on the cardiovascular system in both normotensive and hypotensive rats.
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216
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Liao W, Florén CH. Both the polysaccharide and lipid A parts of endotoxins are needed for the inhibitory effects of endotoxins on cellular LDL uptake. Scand J Clin Lab Invest 1992; 52:183-8. [PMID: 1411250 DOI: 10.3109/00365519209088783] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We previously reported that endotoxins inhibit low-density lipoprotein (LDL) uptake and degradation in Hep G2 cells. In the present study, we tried to elucidate which part(s) of the endotoxin molecules contribute(s) to the inhibitory effect of endotoxins on LDL uptake and degradation. The results show that the endotoxin isolated from Salmonella minnesota Re595 (Re mutant), which lacks polysaccharide, had no effect on the uptake and degradation of 125I-labelled LDL in Hep G2 cells. This mutant form also decreased the inhibitory effects of endotoxins which have complete polysaccharides on cellular LDL uptake and degradation. However, the polysaccharide part of endotoxins by itself had no effect on LDL catabolism by the cells. This suggests that both the polysaccharide and the lipid A parts of endotoxins are needed for the inhibitory effects of endotoxins on LDL uptake and degradation.
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217
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Liao W, Florén CH. Polymyxin B enhances low density lipoprotein catabolism in hepatic and extrahepatic cells. ARTERIOSCLEROSIS AND THROMBOSIS : A JOURNAL OF VASCULAR BIOLOGY 1992; 12:503-11. [PMID: 1313696 DOI: 10.1161/01.atv.12.4.503] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We investigated the effects of polymyxin B (PMB), an antibiotic that binds to endotoxins, on the uptake and degradation of low density lipoproteins (LDLs) in HepG2 cells, a highly differentiated human hepatoma cell line. The results showed that PMB very effectively enhanced the binding, internalization, and degradation of LDL in HepG2 cells. The PMB-mediated enhancement of LDL uptake was not dependent on the LDL receptor-mediated pathway, as blockage of the LDL receptor by use of a monoclonal anti-LDL receptor antibody had no effect on the PMB-mediated cellular processing of LDL and PMB-mediated enhancement of LDL uptake did not cause an increase in cholesterol esterification. In addition, chloroquine and colchicine, which inhibit lysosomal degradation and cellular endocytosis, respectively, diminished PMB-enhanced degradation of LDL, indicating that PMB mediates uptake through a pathway similar to the LDL receptor-mediated pathway. The PMB-mediated uptake of LDL was sensitive to treatment with phospholipase C and pronase and was dependent on the presence of Ca2+. PMB caused similar changes in human skin fibroblasts, bovine smooth muscle cells, and bovine endothelial cells, which suggests that PMB-enhanced LDL uptake is a general cellular phenomenon. Our results thus indicate that PMB increases cellular catabolism of LDL through an endocytotic pathway not involving the LDL receptors.
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MESH Headings
- Animals
- Calcium/pharmacology
- Carcinoma, Hepatocellular
- Cattle
- Cells, Cultured
- Chloroquine/pharmacology
- Colchicine/pharmacology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Fibroblasts/drug effects
- Fibroblasts/metabolism
- Humans
- Lipoproteins, LDL/metabolism
- Liver/drug effects
- Liver/metabolism
- Liver Neoplasms
- Muscle, Smooth/drug effects
- Muscle, Smooth/metabolism
- Polymyxin B/pharmacology
- Pronase/pharmacology
- Receptors, LDL/antagonists & inhibitors
- Receptors, LDL/physiology
- Tumor Cells, Cultured
- Type C Phospholipases/pharmacology
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218
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Matthews MM, Liao W, Kvalnes-Krick KL, Traut TW. beta-Alanine synthase: purification and allosteric properties. Arch Biochem Biophys 1992; 293:254-63. [PMID: 1536562 DOI: 10.1016/0003-9861(92)90393-b] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
beta-Alanine synthase has been purified greater than 1000-fold to homogeneity from rat liver. The enzyme has a subunit molecular weight of 42,000 and a native size of hexamer. The enzyme undergoes ligand-induced changes in polymerization: association in response to the substrate, N-carbamoyl-beta-alanine, and the inhibitor, propionate; and dissociation in response to the product, beta-alanine. The ability of the substrate to associate the pure native enzyme to a larger polymeric species was exploited in the final purification step. The purified enzyme had a pI of 6.7, a Km of 8 microM, and a kcat/Km of 7.9 x 10(4) M-1 s-1. Positive cooperativity was observed toward the substrate N-carbamoyl-beta-alanine, with nH = 1.9. Such cooperativity occurred at substrate concentrations below 12 nM, so that this activation most likely occurs at a regulatory site, with a significantly stronger affinity for N-carbamoyl-beta-alanine than that shown by the catalytic site. The enzyme was sensitive to denaturation, which could be minimized by avoiding heat steps during the purification and by the presence of reducing agents. Such denatured enzyme had little change in Vmax, but had much higher Km, and had also lost the ability to associate or dissociate in response to effectors. After purification, enzyme stability was achieved by the addition of glycerol and detergent.
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219
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Liu P, Perryman MB, Liao W, Siciliano MJ. Efficiency and limitations of the hn-cDNA library approach for the isolation of human transcribed genes from hybrid cells. ACTA ACUST UNITED AC 1992; 18:7-18. [PMID: 1372133 DOI: 10.1007/bf01233445] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The use of splice donor site consensus sequences as primers in cDNA synthesis (to make a cDNA library from heterogeneous RNA or unprocessed transcript--an hn-cDNA library) and the screening of such an hn-cDNA library with human repeat DNA probe in order to isolate human genes from somatic cell hybrids have been demonstrated. Here, we optimize and evaluate the efficiency and limitations of the approach. Computer analysis of genomic sequences of 22 randomly selected human genes indicated that hexamers CTTACC, CTCACC, and CCTACC were most efficient at beginning first-strand cDNA synthesis at donor splice sites of hnRNA and suggested that the procedure is efficient for priming cDNA synthesis of at least one exon from most every gene. Primer extension experiments established conditions in which the primers would initiate synthesis of cDNA starting from a perfectly matched position on the RNA template at more than 60-fold higher yield than any other product. By isolation of a clone containing exon III of the human DNA repair gene ERCC1, we indicate that the approach is capable of cloning exons from weakly expressed genes. Sequencing of clones revealed a structure of hn-cDNA clones consistent with the expectations of the cloning strategy and indicated the potential of the clones in detecting polymorphisms. Finally, we demonstrate that the expression of these hn-cDNA sequences in cells can be detected efficiently at the hnRNA level by reverse transcriptase-polymerase chain reaction (RT/PCR).
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Liao W, Joe T, Cusick WG. Multiresidue screening method for fresh fruits and vegetables with gas chromatographic/mass spectrometric detection. JOURNAL - ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS 1991; 74:554-65. [PMID: 1874703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A gas chromatographic/mass spectrometric (GC/MS) screening method has been developed for the determination of pesticide residues in a variety of crop samples. Samples are extracted with acetonitrile and partitioned with sodium chloride saturated aqueous solution. Targeted pesticide analytes are separated on a short, narrow bore capillary column, identified by electron ionization MS scanned from 100 to 400 amu, and quantitated by the monitoring of base ions and internal standards. The accuracy of the quantitative determination measured in terms of average percentage recovery of 143 compounds in 13 crop samples was 92% with a relative standard deviation of 22%.
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Liao W. [Serotonin and monoamine metabolites in cerebrospinal fluid in children: interrelationships and the influence of age, sex and precursor]. ZHONGHUA SHEN JING JING SHEN KE ZA ZHI = CHINESE JOURNAL OF NEUROLOGY AND PSYCHIATRY 1991; 24:41-4, 63. [PMID: 1651218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cerebrospinal fluid and blood were taken from 15 non-neurologic children. Tryptophan(Trp), 5-HTP, 5-HT, 5-HIAA, HVA, MHPG in CSF, and 5-HT, free and total Trp(F-Trp and T-Trp) in serum were determined by HPLC method. Results showed that Trp, 5-HTP, 5-HT, 5-HIAA in CSF were positively correlated significantly. Good correlations were also found between F-Trp in serum and Trp in CSF (C-Trp), 5-HIAA and HVA, 5-HTP and MHPG. C-Trp, 5-HTP, 5-HT, 5-HIAA and HVA declined significantly with increasing age. MHPG was higher in male than in female children.
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Liao W, Smith WD, Chiang TC, Williams LR. Rapid, low-cost cleanup procedure for determination of semivolatile organic compounds in human and bovine adipose tissues. JOURNAL - ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS 1988; 71:742-7. [PMID: 3417593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A gas chromatographic/mass spectrometric (GC/MS) method is described for determination of organic environmental pollutants in human and bovine adipose tissues. Compounds such as organochlorine pesticides, polychlorinated biphenyls, polynuclear aromatic hydrocarbons, polychlorinated aromatics, and brominated aromatics are extracted with organic solvents and separated from coextracted lipids on a Florisil column. The eluate is concentrated and compounds are identified and quantitated by GC/MS analysis. The method was evaluated in a single laboratory for ability to recover compounds of environmental and regulatory importance. Except for a few more polar compounds, such as phthalates and phosphates, recoveries averaged about 85%. The elution system maximized recovery and allowed minimal coelution of lipid materials. Detection limits for most compounds studied were in the range of 5-50 ng/g (ppb).
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Stanley LA, Adams DJ, Lindsay R, Meehan RR, Liao W, Wolf CR. Potentiation and suppression of mouse liver cytochrome P-450 isozymes during the acute-phase response induced by bacterial endotoxin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 174:31-6. [PMID: 3131144 DOI: 10.1111/j.1432-1033.1988.tb14058.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Infection and inflammation are known to affect the metabolism and disposition of drugs and carcinogens. We report a detailed study of the effects of bacterial endotoxin on the constitutive and inducible expression and activities of cytochrome P-450 isozymes from families P-450I, P-450IIB, P-450IIC and P-450III. In general high doses of high endotoxin caused very marked suppression of P-450 isozymes and associated activities. However, this effect was differential, the expression of certain isozymes being only slightly reduced whereas others were suppressed to almost undetectable levels. Low doses of endotoxin also gave differential effects on cytochrome P-450 expression. Of particular interest was the very marked potentiation of the inductive effect of both 3-methylcholanthrene and phenobarbital. In the case of 3-methylcholanthrene the 10-fold induction of activity was increased to 24-fold by concomitant endotoxin administration. In this regard it was interesting that 3-methylcholanthrene was an effective inducer of a wide variety of acute-phase proteins including metallothionein, serum amyloid A, fibrinogen and hemopexin. These data show that endotoxin, and therefore bacterial infection and inflammation, can have profound and differential effects on components of the cytochrome-P-450 monooxygenase system which could result in significant changes in susceptibility to the effects of drugs, chemical toxins and carcinogens.
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Liao W. Replica-symmetric solution of the graph-bipartitioning problem. PHYSICAL REVIEW. A, GENERAL PHYSICS 1988; 37:587-595. [PMID: 9899690 DOI: 10.1103/physreva.37.587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Chiang TC, Liao W, Williams LR. Use of solid phase Florisil cartridges to separate fat from semivolatile organic compounds in adipose tissue. JOURNAL - ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS 1987; 70:100-2. [PMID: 3031005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A quick method for separation of semivolatile organic compounds from fat in adipose tissue has been developed. This method uses commercially available solid phase cartridges for sample cleanup. The results indicate that the recoveries, from hexane-extracted fat, of 4 representative classes of organic compounds range from 86.2 to 116%. The solid phase cartridges provide excellent separations of the fat from the analytes; no extraneous interference peaks were detected in the gas chromatograms. The method requires only 0.1 g sample and is quick and simple to use. Although results are reported for samples containing 1-14 ppm, the final extract can be concentrated to a volume allowing detection between 10 and 100 ppb.
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Liao W, Christman RF, Johnson JD, Millington DS, Hass JR. Structural characterization of aquatic humic material. ENVIRONMENTAL SCIENCE & TECHNOLOGY 1982; 16:403-410. [PMID: 22276756 DOI: 10.1021/es00101a007] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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228
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Dorman MR, Brown TR, Smith MC, Liao W. Do administrators' views show why hospitals do or don't use unit doses? HOSPITALS 1978; 52:107-9. [PMID: 700656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A survey of hospital administrators showed some expected correlations and some surprising contradictions between their opinions of the unit dose system and their institutions' policies on use of the system. The survey indicated that hospital administrators need to be better informed about many of the advantages and disadvantages of the unit dose system and that communication with the hospital pharmacists strongly influences their opinions.
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Hayman JN, Brown TR, Smith MC, Liao W. Physician use and evaluation of a hospital-based drug information center. AMERICAN JOURNAL OF HOSPITAL PHARMACY 1978; 35:1238-40. [PMID: 696732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The use of a hospital-based information center by physicians was investigated. A questionnaire was used to gather information from physicians using the services of the center. The study was conducted over a six-month period. Of the 126 questionnaires distributed, 115 (91.1%) were completed and returned. The number of physicians studied was 100. The five categories of drug information most frequently requested involved adverse reactions, dosage, therapeutic use, availability and toxicity. Physicians used information most frequently for purposes of direct patient care. Evaluations of the quality, accuracy and quantity of information provided by the center were high. Physicians using information for purposes of direct patient care felt the information was clinically significant. Although certain inadequacies were identified, it was concluded that the center serves as a reliable source of comprehensive and accurate drug information for physicians.
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Liao W, Boak G, Huq M. Myoglobinuria and acute renal failure. THE JOURNAL OF THE MEDICAL SOCIETY OF NEW JERSEY 1978; 75:167-9. [PMID: 271744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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231
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Liao W. Psychological stress, health status, and health behavior: application of the life changes concept. Psychol Rep 1977; 41:246. [PMID: 909994 DOI: 10.2466/pr0.1977.41.1.246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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