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Chang JY, Liu LZ. Manganese potentiates nitric oxide production by microglia. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 68:22-8. [PMID: 10320780 DOI: 10.1016/s0169-328x(99)00082-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Manganese toxicity has been associated with clinical symptoms of neurotoxicity which are similar to the symptoms observed in Parkinson's disease. Earlier reports indicated that reactive microglia was present in the substantia nigra of patients with Parkinson's disease. Using N9 microglial cells, the current study was designed to determine whether high levels of manganese were associated with microglial activation. Results indicated that manganese significantly increased the bacterial lipopolysaccharide-induced nitric oxide production. This potent activity of manganese was not shared by other transition metals tested, including iron, cobalt, nickel, copper and zinc. Immunohistochemical staining and Western blot analysis indicated that manganese increased the cellular production of inducible nitric oxide synthase. Northern blot analysis indicated that manganese likely increased iNOS gene transcription since this agent increased the mRNA level of the inducible nitric oxide synthase. In contrast to other transition metals tested, manganese did not appear to be cytotoxic to microglial cells. These results suggested that manganese could induce sustained production of neurotoxic nitric oxide by activated microglial cells, which might cause detrimental consequences to surrounding neurons.
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Xu WM, Liu LZ. Nitric oxide: from a mysterious labile factor to the molecule of the Nobel Prize. Recent progress in nitric oxide research. Cell Res 1998; 8:251-8. [PMID: 9934533 DOI: 10.1038/cr.1998.25] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
NO is now known to be an important messenger molecule in biology. It regulates a variety of functions within cells and tissues including vasodilation, neurotransmission and immunological process. This review will focus on the nitric oxide synthase gene family and recent progress on molecular genetic analysis of NOS1, NOS2 and NOS3 genes.
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Chang JY, Chavis JA, Liu LZ, Drew PD. Cholesterol oxides induce programmed cell death in microglial cells. Biochem Biophys Res Commun 1998; 249:817-21. [PMID: 9731219 DOI: 10.1006/bbrc.1998.9237] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
N9 microglial cells were used as a model to examine the effect of cholesterol oxides on central nervous system microglia. Results indicated that 25-OH-cholesterol was the most cytotoxic agent among the cholesterol oxides tested. During the process of cell death, this agent caused prominent nuclei condensation and significant DNA fragmentation, a phenomenon association with programmed cell death. Cholesterol oxides were able to potentiate the bacterial lipopolysaccharide (LPS)-induced nitric oxide production to various degrees. Consistent with this finding, Northern blot analysis indicated that 25-OH-cholesterol potentiated the LPS-induced nitric oxide synthase RNA levels. The cytotoxicity of 25-OH-cholesterol could be prevented by methyl-beta-cyclodextrin, a glucose polymer known to cause cholesterol oxide efflux from cells. While much attention has been focused on the cytotoxicity of cholesterol oxides on immune cells within the blood, including lymphocytes and macrophages, the results from this study indicated for the first time that these agents are toxic to microglial cells derived from the central nervous system.
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Abstract
Cultured rat cerebellar granule cells were used to determine the potential neurotoxicity of cholesterol oxides. The cholesterol oxides tested included: 7-beta-OH-, 7-keto-, 19-OH-, 22(R)-OH-, 22(S)-OH- and 25-OH- cholesterol. Among them, 7-beta-OH- and 7-keto-cholesterol were the most efficacious in causing neuronal death such that 20 microg/ml (50 microM) of these agents killed more than 80% of cells in 2 days. 7-beta-OH-cholesterol at this concentration killed 50% of cells in approximately 7 h. A number of pharmacological agents were tested for their abilities to prevent neuronal death induced by cholesterol oxides. Among them, aurintricarboxylic acid, vitamin E and methyl-beta-cyclodextrin were able to prevent cholesterol oxide-induced neurotoxicity in a dose-dependent manner. These results suggest that, in addition to causing pathological changes in cells directly involved in atherosclerosis, cholesterol oxides may induce toxicity in neurons of the central nervous system.
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Abstract
PC12 cells induced to differentiate with nerve growth factor were used to study the neurotoxicity of 25-OH-cholesterol. This agent induced a dose- and time-dependent cell death in neuronal PC12 cells. Cells treated with this agent showed condensed nuclei, a morphology similar to that of cells dying of programmed cell death. However, agents known to prevent neuronal programmed cell death (cyclic AMP, KCl, aurintricarboxylic acid, and cycloheximide) failed to prevent the 25-OH-cholesterol-mediated cytotoxicity. On the other hand, cell death induced by 25-OH-cholesterol was prevented by treatment with vitamin E and methyl-beta-cyclodextrin. In contrast to observations made in other cell types, whole-cell patch clamp recording of neuronal PC12 cells revealed that treatment with 25-OH-cholesterol did not significantly alter calcium influx through voltage-dependent channels. These results provide the first characterization of the toxicity of cholesterol oxides toward neuronal PC12 cells, which should be useful in future studies on the interactions between cholesterol oxides and cells from the nervous system.
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Abstract
PURPOSE By using nerve growth factor-differentiated PC12 cells as a model for sympathetic neurons, we have recently shown that cholesterol oxides are toxic to cells of neural origin. Since lipid metabolism is known to be involved in some pathological conditions associated with the visual system, we sought to extend this line of research by studying the potential cytotoxicity of cholesterol oxides on primary cultures derived from neuroretinas. METHODS Dissociated cultures derived from neuroretinas of 1-day-old Sprague-Dawley rats were used in this series of studies. Immunohistochemical staining was used to identify neuronal and glial cell types in these cultures. MTT assay was used to determine the cytotoxicity of cholesterol oxides, including 7-beta-OH-, 7-keto-, 19-OH-, 22(R)-OH-, 22(S)-OH- and 25-OH-cholesterol. RESULTS Among the cholesterol oxides tested, 7-beta-OH- and 7-keto-cholesterol were the most effective in causing cell death, such that 20 micrograms/ml (50 microM) of these agents killed approximately 80% of cells in 3 days. A time-dependent experiment indicated that 10 micrograms/ml of 7-beta-cholesterol was able to kill 50% of cells in approximately 5 h. A number of pharmacological agents were tested for their ability to prevent cell death induced by cholesterol oxides. Among them, vitamin E and methyl-beta-cyclodextrin were able to prevent cholesterol oxide-induced cell death in a dose-dependent manner. CONCLUSIONS These results suggest that, in addition to causing pathological changes in cells directly involved in atherosclerosis, cholesterol oxides may be toxic to cells derived from neuroretinas.
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Chang JY, Phelan KD, Liu LZ. Establishment of two morphologically distinct PC12 cell lines resistant to 25-OH-cholesterol toxicity. Biochem Biophys Res Commun 1997; 239:429-34. [PMID: 9344846 DOI: 10.1006/bbrc.1997.7481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Two novel populations of spontaneous PC12 cell mutants resistant to a toxic concentration of 25-OH-cholesterol (5 microg/ml, 12.5 microM) were isolated and designated as R25R and F25R based on cell morphology. R25R consisted of round cells that were morphologically similar to the parent PC12 cells, and responded to nerve growth factor by extending neurites. F25R was a group of process-bearing flat cells that did not assume a neuronal morphology in the presence of nerve growth factor. These two cell lines also acquired some cross-resistance toward other cholesterol oxides. Nerve growth factor induced prominent voltage-dependent calcium currents in parent PC12 cells and in R25R, but not in F25R. Further experiments indicated that the parent PC12 cells, R25R and F25R exhibited different properties when challenged with a variety of toxic insults, including amphotericin B, serum withdrawal and beta-amyloid protein treatment.
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Chang JY, Liu LZ. 25-Hydroxycholesterol causes death but does not prevent nerve growth factor-induced neurite outgrowth in PC12 cells. Neurochem Int 1997; 31:517-23. [PMID: 9308000 DOI: 10.1016/s0197-0186(97)00020-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effects of cholesterol oxides on regular and neuronal PC12 cells were examined. Among the cholesterol oxides tested, 7-beta-, 22(R)- and 25-OH-cholesterol were very toxic to regular PC12 cells such that approximately 80% of cells were killed after a 3 day incubation with 20 micrograms/ml (50 microM) of these agents. Cholesterol oxides caused cytotoxicity in neuronal PC12 cells at concentrations higher than those observed for regular PC12 cells. The nerve growth factor (NGF)-induced neurite outgrowth and nitric oxide synthase expression appeared normal in PC12 cells treated with a sublethal dose of 25-OH-cholesterol. Neurite regeneration from established neuronal PC12 cells was not inhibited by the presence of a toxic dose of 25-OH-cholesterol. Given the fact that 25-OH-cholesterol is a potent inhibitor of cholesterol synthesis pathway, these results suggest that the de novo synthesis of cholesterol may not be required for NGF-induced neurite outgrowth in PC12 cells.
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Xu J, Liu LZ, Deng XF, Timmons L, Hersperger E, Steeg PS, Veron M, Shearn A. The enzymatic activity of Drosophila AWD/NDP kinase is necessary but not sufficient for its biological function. Dev Biol 1996; 177:544-57. [PMID: 8806830 DOI: 10.1006/dbio.1996.0184] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The Drosophila abnormal wing discs (awd) gene encodes the subunit of a protein that has nucleoside diphosphate kinase (NDP kinase) activity. Null mutations of the awd gene cause lethality after puparium formation. Larvae homozygous for such mutations have small imaginal discs, lymph glands, and brain lobes. Neither the imaginal discs nor the ovaries from such null mutant larvae are capable of further growth or normal differentiation when transplanted into suitable host larvae. This null mutant phenotype can be entirely rescued by one copy of a transgene that has 750 bp of awd upstream regulatory DNA fused to a full-length awd cDNA. Tissue-specific expression of AWD protein from this rescue transgene is identical to tissue-specific expression of beta-galactosidase from a reporter transgene that has the same regulatory region fused to the bacterial lac Z gene. However, this rescue transgene or reporter transgene expression pattern is only a subset of the endogenous pattern of expression detected by either in situ hybridization or immunohistochemistry. This suggests that awd is normally expressed in some tissues where it is not required. The null mutant phenotype cannot be rescued at all by a transgene that has 750 bp of awd upstream regulatory DNA fused to a full-length awd cDNA with a mutation that eliminates NDP kinase activity by replacement of the active site histidine with alanine. This suggests that the enzymatic activity of the AWD protein is necessary for its biological function. The human genes nm23-H1 and nm23-H2 encode NDP kinase A and B subunits, respectively. The protein subunit encoded by either human nm23 gene is 78% identical to that encoded by the Drosophila awd gene. Transgenes that have the 750-bp awd upstream regulatory DNA fused to human nm23-H2 cDNA but not to nm23-H1 cDNA can rescue the imaginal disc phenotype and the zygotic lethality caused by homozygosis for an awd null mutation as efficiently as an awd transgene. However, rescue of female sterility requires twice as much nm23-H2 expression as awd expression. This implies that the enzymatic activity of the AWD protein is not sufficient for its biological function. The biological function may require nonconserved residues of the AWD protein that allow it to interact with other proteins.
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Liu LZ, Shearn A. Rapid PCR for RNA differential display in a conventional heat block thermal cycler. Biotechniques 1995; 19:44-6. [PMID: 7545408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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Kang J, Yang CJ, Lee YP, Olson CG, Cho E, Oh S, Anderson RO, Liu LZ, Park J, Allen JW, Ellis WP. Photoemission study of SmCo2. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:10327-10334. [PMID: 10007311 DOI: 10.1103/physrevb.48.10327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Timmons L, Hersperger E, Woodhouse E, Xu J, Liu LZ, Shearn A. The expression of the Drosophila awd gene during normal development and in neoplastic brain tumors caused by lgl mutations. Dev Biol 1993; 158:364-79. [PMID: 8393813 DOI: 10.1006/dbio.1993.1195] [Citation(s) in RCA: 41] [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]
Abstract
The abnormal wing discs (awd) gene of Drosophila is homologous to the nm23 gene of mammals, a gene whose expression is altered in metastatic tumors. Both awd and nm23 encode nucleoside diphosphate kinases (NDP kinases). We have examined the accumulation of AWD/NDP kinase during normal development by assaying enzyme activity in extracts. There is a nearly constant level of activity throughout larval and pupal development. We have examined the tissue-specific transcription of the awd gene by RNA in situ hybridization and by reporter gene expression. In imaginal discs and brains there is no detectable awd gene expression until the beginning of the third larval instar, despite the constant level of enzyme activity measured in extracts of larvae and pupae. The most intense awd gene expression in imaginal discs and brains occurs after the end of larval development. We have also examined awd gene expression in neoplastic brain tumors caused by mutations in the lethal giant larvae (lgl) gene. In lgl mutant brains, as in normal brains, awd gene expression begins during the third larval instar. No tumors form in brains from lgl-; awd- double mutant larva, so awd gene expression is required for tumor formation and/or proliferation. There is more accumulation of AWD/NDP kinase in lgl- mutant brains than there is in normal brains. Using an awd reporter gene, we show that this is a consequence of an increased proportion of awd gene-expressing cells in mutant brains. Using the same awd reporter gene as a marker of donor cells, we have confirmed the invasiveness of lgl-induced neuroblastomas.
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Anderson RO, Claessen R, Allen JW, Olson CG, Janowitz C, Liu LZ, Park J, Maple MB, Dalichaouch Y, Jardim RF, Early EA, Oh S, Ellis WP. Luttinger Fermi surface of metallic gap spectral weight in Nd1.85Ce0.15CuO4-y. PHYSICAL REVIEW LETTERS 1993; 70:3163-3166. [PMID: 10053791 DOI: 10.1103/physrevlett.70.3163] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Allen JW, Liu LZ. alpha - gamma transition in Ce. II. A detailed analysis of the Kondo volume-collapse model. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:5047-5054. [PMID: 10004278 DOI: 10.1103/physrevb.46.5047] [Citation(s) in RCA: 136] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Liu LZ, Allen JW, Gunnarsson O, Christensen NE, Andersen OK. alpha - gamma transition in Ce: A detailed analysis of electron spectroscopy. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:8934-8941. [PMID: 10000753 DOI: 10.1103/physrevb.45.8934] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Liu LZ, Allen JW, Seaman CL, Maple MB, Dalichaouch Y, Kang J, Torikachvili MS. Kondo resonance in Y1-xUxPd3. PHYSICAL REVIEW LETTERS 1992; 68:1034-1037. [PMID: 10046061 DOI: 10.1103/physrevlett.68.1034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Seaman CL, Maple MB, Lee BW, Ghamaty S, Torikachvili MS, Kang J, Liu LZ, Allen JW, Cox DL. Evidence for non-Fermi liquid behavior in the Kondo alloy Y1-xUxPd3. PHYSICAL REVIEW LETTERS 1991; 67:2882-2885. [PMID: 10044578 DOI: 10.1103/physrevlett.67.2882] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Xu WM, Cheng XF, Hong LS, Liu LZ, Bao Y, He RG, Zhou XJ, Shen ZZ, Qui WQ, Ponder B. The gene for von Recklinghausen neurofibromatosis (NF1) maps to the pericentromeric region of chromosome 17 in Chinese families. Genomics 1991; 10:1090-2. [PMID: 1916815 DOI: 10.1016/0888-7543(91)90206-t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Linkage analysis of six Chinese families with neurofibromatosis type 1 (NF1) confirms the location of the NF1 gene to the region of the proximal long arm of chromosome 17, as in Caucasian populations. The diagnosis of NF1 was made according to internationally accepted criteria. The markers used were D17S71, D17S58, D17S33, and EVI2A. The overall odds in favor of NF1 lying within this linkage group in the families studied are over 150,000:1, with a maximum location score of 5.112 for the interval D17S58-EVI2A.
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Gunnarsson O, Allen JW, Jepsen O, Fujiwara T, Andersen OK, Olsen CG, Maple MB, Kang J, Liu LZ, Park J, Anderson RO, Ellis WP, Liu R, Markert JT, Dalichaouch Y, Shen Z, Lindberg PA, Wells BO, Dessau DS, Borg A, Lindau I, Spicer WE. Polarized resonance photoemission for Nd2CuO4. PHYSICAL REVIEW. B, CONDENSED MATTER 1990; 41:4811-4814. [PMID: 9994326 DOI: 10.1103/physrevb.41.4811] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Allen JW, Olson CG, Maple MB, Kang J, Liu LZ, Park J, Anderson RO, Ellis WP, Markert JT, Dalichaouch Y, Liu R. Resonant photoemission study of Nd2-xCexCuO4-y: Nature of electronic states near the Fermi level. PHYSICAL REVIEW LETTERS 1990; 64:595-598. [PMID: 10042024 DOI: 10.1103/physrevlett.64.595] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Zhu YX, Liu LZ, Ling DK, Wang W. [Chemical studies on the constituents of radix Ophiopogonis]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1989; 14:359-60, 383. [PMID: 2511862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this paper four compounds isolated from Radix Ophiopogonis are described. Their structures have been identified as beta-sitosterol (I), 6-aldehydo-7-methoxy-isoophiopogonanone B (II), beta-sitosterol-beta-D-glucopyranoside (III) and 1-borneol-beta-D-apisyl-beta-D-glucopyranoside (IV) on the basis of spectral data and hydrolytic reaction.
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Liu LZ, Song ZC, Feng CY, Huang FS, Chen FZ. Establishment of a natural mating colony of Anopheles dirus Peyton ET Harrison and their biological characteristics. Chin Med J (Engl) 1987; 100:230-3. [PMID: 3113847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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Liu LZ. [Nursing of patients undergoing transplantation of the pedicled greater omentum to the brain]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1985; 20:27-8. [PMID: 3846497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Liu LZ. [Peculiarities of nursing in traditional Chinese medicine]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1984; 19:270-2. [PMID: 6570658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Liu LZ. [Care of patients with an intestinal fistula]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1984; 19:36-8. [PMID: 6564934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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