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Sarin SK, Kumar M, Lau GK, Abbas Z, Chan HLY, Chen CJ, Chen DS, Chen HL, Chen PJ, Chien RN, Dokmeci AK, Gane E, Hou JL, Jafri W, Jia J, Kim JH, Lai CL, Lee HC, Lim SG, Liu CJ, Locarnini S, Al Mahtab M, Mohamed R, Omata M, Park J, Piratvisuth T, Sharma BC, Sollano J, Wang FS, Wei L, Yuen MF, Zheng SS, Kao JH. Asian-Pacific clinical practice guidelines on the management of hepatitis B: a 2015 update. Hepatol Int 2016; 10:1-98. [PMID: 26563120 PMCID: PMC4722087 DOI: 10.1007/s12072-015-9675-4] [Citation(s) in RCA: 1899] [Impact Index Per Article: 211.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/14/2015] [Indexed: 02/06/2023]
Abstract
Worldwide, some 240 million people have chronic hepatitis B virus (HBV), with the highest rates of infection in Africa and Asia. Our understanding of the natural history of HBV infection and the potential for therapy of the resultant disease is continuously improving. New data have become available since the previous APASL guidelines for management of HBV infection were published in 2012. The objective of this manuscript is to update the recommendations for the optimal management of chronic HBV infection. The 2015 guidelines were developed by a panel of Asian experts chosen by the APASL. The clinical practice guidelines are based on evidence from existing publications or, if evidence was unavailable, on the experts' personal experience and opinion after deliberations. Manuscripts and abstracts of important meetings published through January 2015 have been evaluated. This guideline covers the full spectrum of care of patients infected with hepatitis B, including new terminology, natural history, screening, vaccination, counseling, diagnosis, assessment of the stage of liver disease, the indications, timing, choice and duration of single or combination of antiviral drugs, screening for HCC, management in special situations like childhood, pregnancy, coinfections, renal impairment and pre- and post-liver transplant, and policy guidelines. However, areas of uncertainty still exist, and clinicians, patients, and public health authorities must therefore continue to make choices on the basis of the evolving evidence. The final clinical practice guidelines and recommendations are presented here, along with the relevant background information.
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Practice Guideline |
9 |
1899 |
2
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Hyeon T, Lee SS, Park J, Chung Y, Na HB. Synthesis of highly crystalline and monodisperse maghemite nanocrystallites without a size-selection process. J Am Chem Soc 2001; 123:12798-801. [PMID: 11749537 DOI: 10.1021/ja016812s] [Citation(s) in RCA: 1027] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The synthesis of highly crystalline and monodisperse gamma-Fe(2)O(3) nanocrystallites is reported. High-temperature (300 degrees C) aging of iron-oleic acid metal complex, which was prepared by the thermal decomposition of iron pentacarbonyl in the presence of oleic acid at 100 degrees C, was found to generate monodisperse iron nanoparticles. The resulting iron nanoparticles were transformed to monodisperse gamma-Fe(2)O(3) nanocrystallites by controlled oxidation by using trimethylamine oxide as a mild oxidant. Particle size can be varied from 4 to 16 nm by controlling the experimental parameters. Transmission electron microscopic images of the particles showed 2-dimensional and 3-dimensional assembly of particles, demonstrating the uniformity of these nanoparticles. Electron diffraction, X-ray diffraction, and high-resolution transmission electron microscopic (TEM) images of the nanoparticles showed the highly crystalline nature of the gamma-Fe(2)O(3) structures. Monodisperse gamma-Fe(2)O(3) nanocrystallites with a particle size of 13 nm also can be generated from the direct oxidation of iron pentacarbonyl in the presence of oleic acid with trimethylamine oxide as an oxidant.
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24 |
1027 |
3
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Soci C, Zhang A, Xiang B, Dayeh SA, Aplin DPR, Park J, Bao XY, Lo YH, Wang D. ZnO nanowire UV photodetectors with high internal gain. NANO LETTERS 2007; 7:1003-9. [PMID: 17358092 DOI: 10.1021/nl070111x] [Citation(s) in RCA: 836] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
ZnO nanowire (NW) visible-blind UV photodetectors with internal photoconductive gain as high as G approximately 108 have been fabricated and characterized. The photoconduction mechanism in these devices has been elucidated by means of time-resolved measurements spanning a wide temporal domain, from 10-9 to 102 s, revealing the coexistence of fast (tau approximately 20 ns) and slow (tau approximately 10 s) components of the carrier relaxation dynamics. The extremely high photoconductive gain is attributed to the presence of oxygen-related hole-trap states at the NW surface, which prevents charge-carrier recombination and prolongs the photocarrier lifetime, as evidenced by the sensitivity of the photocurrrent to ambient conditions. Surprisingly, this mechanism appears to be effective even at the shortest time scale investigated of t < 1 ns. Despite the slow relaxation time, the extremely high internal gain of ZnO NW photodetectors results in gain-bandwidth products (GB) higher than approximately 10 GHz. The high gain and low power consumption of NW photodetectors promise a new generation of phototransistors for applications such as sensing, imaging, and intrachip optical interconnects.
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Evaluation Study |
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836 |
4
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Abstract
There have been several recent studies concerning feedforward networks and the problem of approximating arbitrary functionals of a finite number of real variables. Some of these studies deal with cases in which the hidden-layer nonlinearity is not a sigmoid. This was motivated by successful applications of feedforward networks with nonsigmoidal hidden-layer units. This paper reports on a related study of radial-basis-function (RBF) networks, and it is proved that RBF networks having one hidden layer are capable of universal approximation. Here the emphasis is on the case of typical RBF networks, and the results show that a certain class of RBF networks with the same smoothing factor in each kernel node is broad enough for universal approximation.
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34 |
783 |
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Abstract
SUMMARY DaliLite is a program for pairwise structure comparison and for structure database searching. It is a standalone version of the search engine of the popular Dali server. A web interface is provided to view the results, multiple alignments and 3D superimpositions of structures.
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Comparative Study |
25 |
710 |
6
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Brunet A, Park J, Tran H, Hu LS, Hemmings BA, Greenberg ME. Protein kinase SGK mediates survival signals by phosphorylating the forkhead transcription factor FKHRL1 (FOXO3a). Mol Cell Biol 2001; 21:952-65. [PMID: 11154281 PMCID: PMC86685 DOI: 10.1128/mcb.21.3.952-965.2001] [Citation(s) in RCA: 672] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Serum- and glucocorticoid-inducible kinases (SGKs) form a novel family of serine/threonine kinases that are activated in response to a variety of extracellular stimuli. SGKs are related to Akt (also called PKB), a serine/threonine kinase that plays a crucial role in promoting cell survival. Like Akt, SGKs are activated by the phosphoinositide-3 kinase (PI3K) and translocate to the nucleus upon growth factor stimulation. However the physiological substrates and cellular functions of SGKs remained to be identified. We hypothesized that SGKs regulate cellular functions in concert with Akt by phosphorylating common targets within the nucleus. The best-characterized nuclear substrates of Akt are transcription factors of the Forkhead family. Akt phosphorylates Forkhead transcription factors such as FKHRL1, leading to FKHRL1's exit from the nucleus and the consequent shutoff of FKHRL1 target genes. We show here that SGK1, like Akt, promotes cell survival and that it does so in part by phosphorylating and inactivating FKHRL1. However, SGK and Akt display differences with respect to the efficacy with which they phosphorylate the three regulatory sites on FKHRL1. While both kinases can phosphorylate Thr-32, SGK displays a marked preference for Ser-315 whereas Akt favors Ser-253. These findings suggest that SGK and Akt may coordinately regulate the function of FKHRL1 by phosphorylating this transcription factor at distinct sites. The efficient phosphorylation of these three sites on FKHRL1 by SGK and Akt appears to be critical to the ability of growth factors to suppress FKHRL1-dependent transcription, thereby preventing FKHRL1 from inducing cell cycle arrest and apoptosis. These findings indicate that SGK acts in concert with Akt to propagate the effects of PI3K activation within the nucleus and to mediate the biological outputs of PI3K signaling, including cell survival and cell cycle progression.
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research-article |
24 |
672 |
7
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Mak KF, McGill KL, Park J, McEuen PL. Valleytronics. The valley Hall effect in MoS₂ transistors. Science 2014; 344:1489-92. [PMID: 24970080 DOI: 10.1126/science.1250140] [Citation(s) in RCA: 631] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Electrons in two-dimensional crystals with a honeycomb lattice structure possess a valley degree of freedom (DOF) in addition to charge and spin. These systems are predicted to exhibit an anomalous Hall effect whose sign depends on the valley index. Here, we report the observation of this so-called valley Hall effect (VHE). Monolayer MoS2 transistors are illuminated with circularly polarized light, which preferentially excites electrons into a specific valley, causing a finite anomalous Hall voltage whose sign is controlled by the helicity of the light. No anomalous Hall effect is observed in bilayer devices, which have crystal inversion symmetry. Our observation of the VHE opens up new possibilities for using the valley DOF as an information carrier in next-generation electronics and optoelectronics.
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Research Support, U.S. Gov't, Non-P.H.S. |
11 |
631 |
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Gerber HP, Condorelli F, Park J, Ferrara N. Differential transcriptional regulation of the two vascular endothelial growth factor receptor genes. Flt-1, but not Flk-1/KDR, is up-regulated by hypoxia. J Biol Chem 1997; 272:23659-67. [PMID: 9295307 DOI: 10.1074/jbc.272.38.23659] [Citation(s) in RCA: 534] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Vascular endothelial growth factor (VEGF) and its two endothelial cell-specific receptor tyrosine kinases, Flk-1/KDR and Flt-1, play a key role in physiological and pathological angiogenesis. Hypoxia has been shown to be a major mechanism for up-regulation of VEGF and its receptors in vivo. When we exposed human umbilical vein endothelial cells to hypoxic conditions in vitro, we observed increased levels of Flt-1 expression. In contrast, Flk-1/KDR mRNA levels were unchanged or slightly repressed. These findings suggest a differential transcriptional regulation of the two receptors by hypoxia. To identify regulatory elements involved in the hypoxic response, promoter regions of the mouse Flt-1 and Flk-1/KDR genes were isolated and tested in conjunction with luciferase reporter gene. In transient transfection assays, hypoxia led to strong transcriptional activation of the Flt-1 promoter, whereas Flk-1/KDR transcription was essentially unchanged. Promoter deletion analysis demonstrated a 430-bp region of the Flt-1 promoter to be required for transcriptional activation in response to hypoxia. This region includes a heptamer sequence matching the hypoxia-inducible factor-1 (HIF) consensus binding site previously found in other hypoxia-inducible genes such as the VEGF gene and erythropoietin gene. We further narrowed down the element mediating the hypoxia response to a 40-base pair sequence including the putative HIF binding site. We show that this element acts like an enhancer, since it activated transcription irrespective of its location or orientation in the construct. Furthermore, mutations within the putative HIF consensus binding site lead to impaired transcriptional activation by hypoxia. These findings indicate that, unlike the KDR/Flk-1 gene, the Flt-1 receptor gene is directly up-regulated by hypoxia via a hypoxia-inducible enhancer element located at positions -976 to -937 of the Flt-1 promoter.
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28 |
534 |
9
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Yoon BH, Romero R, Park JS, Kim CJ, Kim SH, Choi JH, Han TR. Fetal exposure to an intra-amniotic inflammation and the development of cerebral palsy at the age of three years. Am J Obstet Gynecol 2000; 182:675-81. [PMID: 10739529 DOI: 10.1067/mob.2000.104207] [Citation(s) in RCA: 522] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The aim of this study was to determine whether fetal exposure to intra-amniotic inflammation and a systemic fetal inflammatory response (funisitis) are associated with the development of cerebral palsy at the age of 3 years. STUDY DESIGN This cohort study included 123 preterm singleton newborns (gestational age at birth, </=35 weeks) born to mothers who underwent amniocentesis and were followed up for >/=3 years. The presence of intra-amniotic inflammation was determined by elevated amniotic fluid concentrations of proinflammatory cytokines such as interleukins 6 and 8 and by amniotic fluid white blood cell count. Cytokine concentrations were measured with sensitive and specific immunoassays. Funisitis was diagnosed in the presence of neutrophil infiltration into the umbilical vessel walls or Wharton jelly. Cerebral palsy was diagnosed by neurologic examination at the age of 3 years. RESULTS Newborns with subsequent development of cerebral palsy had a higher rate of funisitis and were born to mothers with higher median concentrations of interleukins 6 and 8 and higher white blood cell counts in the amniotic fluid compared with newborns without subsequent development of cerebral palsy (funisitis: 75% [9/12] vs 23% [24/105]; interleukin 6: median, 18.9 ng/mL; range, 0. 02-92.5 ng/mL; vs median, 1.0 ng/mL; range, 0.01-115.2 ng/mL; interleukin 8: median, 13.0 ng/mL; range, 0.1-294.5 ng/mL; vs median, 1.2 ng/mL; range, 0.05-285.0 ng/mL; white blood cell count: median, 198 cells/mm(3); range, 0->1000 cells/mm(3); vs median, 3 cells/mm(3); range, 0-19,764 cells/mm(3); P <.01 for each). After adjustment for the gestational age at birth, the presence of funisitis and elevated concentrations of interleukins 6 and 8 in amniotic fluid significantly increased the odds of development of cerebral palsy (funisitis: odds ratio, 5.5; 95% confidence interval, 1.2-24.5; interleukin 6: odds ratio, 6.4; 95% confidence interval, 1. 3-33.0; interleukin 8: odds ratio, 5.9; 95% confidence interval, 1. 1-30.7; P <.05 for each). CONCLUSION Antenatal exposure to intra-amniotic inflammation and evidence of a systemic fetal inflammatory response (funisitis) are strong and independent risk factors for the subsequent development of cerebral palsy at the age of 3 years.
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522 |
10
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Choy JH, Kwak SY, Jeong YJ, Park JS. Inorganic Layered Double Hydroxides as Nonviral Vectors This work was in part supported by the Korean Ministry of Science and Technology through the NRL project and by the Korean Ministry of Education (BSRI-99-3413). S.Y.K. expresses her thanks to the BK21 fellowship. Angew Chem Int Ed Engl 2000; 39:4041-4045. [PMID: 11093198 DOI: 10.1002/1521-3773(20001117)39:22<4041::aid-anie4041>3.0.co;2-c] [Citation(s) in RCA: 521] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25 |
521 |
11
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Kang YK, Koo DB, Park JS, Choi YH, Chung AS, Lee KK, Han YM. Aberrant methylation of donor genome in cloned bovine embryos. Nat Genet 2001; 28:173-7. [PMID: 11381267 DOI: 10.1038/88903] [Citation(s) in RCA: 440] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Despite recent successes in cloning various animal species, the use of somatic cells as the source of donor nuclei has raised many practically relevant questions such as increased abortion rates, high birth weight and perinatal death. These anomalies may be caused by incomplete epigenetic reprogramming of donor DNA. Genome-wide demethylation occurs during early development, 'erasing' gamete-specific methylation patterns inherited from the parents. This process may be a prerequisite for the formation of pluripotent stem cells that are important for the later development. Here, we provide evidence that cloned bovine embryos may have impaired epigenetic reprogramming capabilities. We found highly aberrant methylation patterns in various genomic regions of cloned embryos. Cloned blastocysts closely resembled donor cells in their overall genomic methylation status, which was very different from that of normal blastocysts produced in vitro or in vivo. We found demethylation of the Bov-B long interspersed nuclear element sequence in normal embryos, but not in cloned embryos, in which the donor-type methylation was simply maintained during preimplantation development. There were also significant variations in the degree of methylation among individual cloned blastocysts. Our findings indicate that the developmental anomalies of cloned embryos could be due to incomplete epigenetic reprogramming of donor genomic DNA.
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24 |
440 |
12
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Staunton JE, Slonim DK, Coller HA, Tamayo P, Angelo MJ, Park J, Scherf U, Lee JK, Reinhold WO, Weinstein JN, Mesirov JP, Lander ES, Golub TR. Chemosensitivity prediction by transcriptional profiling. Proc Natl Acad Sci U S A 2001; 98:10787-92. [PMID: 11553813 PMCID: PMC58553 DOI: 10.1073/pnas.191368598] [Citation(s) in RCA: 431] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2001] [Indexed: 11/18/2022] Open
Abstract
In an effort to develop a genomics-based approach to the prediction of drug response, we have developed an algorithm for classification of cell line chemosensitivity based on gene expression profiles alone. Using oligonucleotide microarrays, the expression levels of 6,817 genes were measured in a panel of 60 human cancer cell lines (the NCI-60) for which the chemosensitivity profiles of thousands of chemical compounds have been determined. We sought to determine whether the gene expression signatures of untreated cells were sufficient for the prediction of chemosensitivity. Gene expression-based classifiers of sensitivity or resistance for 232 compounds were generated and then evaluated on independent sets of data. The classifiers were designed to be independent of the cells' tissue of origin. The accuracy of chemosensitivity prediction was considerably better than would be expected by chance. Eighty-eight of 232 expression-based classifiers performed accurately (with P < 0.05) on an independent test set, whereas only 12 of the 232 would be expected to do so by chance. These results suggest that at least for a subset of compounds genomic approaches to chemosensitivity prediction are feasible.
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research-article |
24 |
431 |
13
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Park J, Leong ML, Buse P, Maiyar AC, Firestone GL, Hemmings BA. Serum and glucocorticoid-inducible kinase (SGK) is a target of the PI 3-kinase-stimulated signaling pathway. EMBO J 1999; 18:3024-33. [PMID: 10357815 PMCID: PMC1171384 DOI: 10.1093/emboj/18.11.3024] [Citation(s) in RCA: 428] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Serum and glucocorticoid-inducible kinase (SGK) is a novel member of the serine/threonine protein kinase family that is transcriptionally regulated. In this study, we have investigated the regulatory mechanisms that control SGK activity. We have established a peptide kinase assay for SGK and present evidence demonstrating that SGK is a component of the phosphoinositide 3 (PI 3)-kinase signaling pathway. Treatment of human embryo kidney 293 cells with insulin, IGF-1 or pervanadate induced a 3- to 12-fold activation of ectopically expressed SGK. Activation was completely abolished by pretreatment of cells with the PI 3-kinase inhibitor, LY294002. Treatment of activated SGK with protein phosphatase 2A in vitro led to kinase inactivation. Consistent with the similarity of SGK to other second-messenger regulated kinases, mutation of putative phosphorylation sites at Thr256 and Ser422 inhibited SGK activation. Cotransfection of PDK1 with SGK caused a 6-fold activation of SGK activity, whereas kinase-dead PDK1 caused no activation. GST-pulldown assays revealed a direct interaction between PDK1 and the catalytic domain of SGK. Treatment of rat mammary tumor cells with serum caused hyperphosphorylation of endogenous SGK, and promoted translocation to the nucleus. Both hyperphosphorylation and nuclear translocation could be inhibited by wortmannin, but not by rapamycin.
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research-article |
26 |
428 |
14
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Domínguez Conde C, Xu C, Jarvis LB, Rainbow DB, Wells SB, Gomes T, Howlett SK, Suchanek O, Polanski K, King HW, Mamanova L, Huang N, Szabo PA, Richardson L, Bolt L, Fasouli ES, Mahbubani KT, Prete M, Tuck L, Richoz N, Tuong ZK, Campos L, Mousa HS, Needham EJ, Pritchard S, Li T, Elmentaite R, Park J, Rahmani E, Chen D, Menon DK, Bayraktar OA, James LK, Meyer KB, Yosef N, Clatworthy MR, Sims PA, Farber DL, Saeb-Parsy K, Jones JL, Teichmann SA. Cross-tissue immune cell analysis reveals tissue-specific features in humans. Science 2022; 376:eabl5197. [PMID: 35549406 PMCID: PMC7612735 DOI: 10.1126/science.abl5197] [Citation(s) in RCA: 427] [Impact Index Per Article: 142.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Despite their crucial role in health and disease, our knowledge of immune cells within human tissues remains limited. We surveyed the immune compartment of 16 tissues from 12 adult donors by single-cell RNA sequencing and VDJ sequencing generating a dataset of ~360,000 cells. To systematically resolve immune cell heterogeneity across tissues, we developed CellTypist, a machine learning tool for rapid and precise cell type annotation. Using this approach, combined with detailed curation, we determined the tissue distribution of finely phenotyped immune cell types, revealing hitherto unappreciated tissue-specific features and clonal architecture of T and B cells. Our multitissue approach lays the foundation for identifying highly resolved immune cell types by leveraging a common reference dataset, tissue-integrated expression analysis, and antigen receptor sequencing.
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research-article |
3 |
427 |
15
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Chambers J, Ames RS, Bergsma D, Muir A, Fitzgerald LR, Hervieu G, Dytko GM, Foley JJ, Martin J, Liu WS, Park J, Ellis C, Ganguly S, Konchar S, Cluderay J, Leslie R, Wilson S, Sarau HM. Melanin-concentrating hormone is the cognate ligand for the orphan G-protein-coupled receptor SLC-1. Nature 1999; 400:261-5. [PMID: 10421367 DOI: 10.1038/22313] [Citation(s) in RCA: 413] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The underlying causes of obesity are poorly understood but probably involve complex interactions between many neurotransmitter and neuropeptide systems involved in the regulation of food intake and energy balance. Three pieces of evidence indicate that the neuropeptide melanin-concentrating hormone (MCH) is an important component of this system. First, MCH stimulates feeding when injected directly into rat brains; second, the messenger RNA for the MCH precursor is upregulated in the hypothalamus of genetically obese mice and in fasted animals; and third, mice lacking MCH eat less and are lean. MCH antagonists might, therefore, provide a treatment for obesity. However, the development of such molecules has been hampered because the identity of the MCH receptor has been unknown until now. Here we show that the 353-amino-acid human orphan G-protein-coupled receptor SLC-1 expressed in HEK293 cells binds MCH with sub-nanomolar affinity, and is stimulated by MCH to mobilize intracellular Ca2+ and reduce forskolin-elevated cyclic AMP levels. We also show that SLC-1 messenger RNA and protein is expressed in the ventromedial and dorsomedial nuclei of the hypothalamus, consistent with a role for SLC-1 in mediating the effects of MCH on feeding.
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413 |
16
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Riccardi D, Park J, Lee WS, Gamba G, Brown EM, Hebert SC. Cloning and functional expression of a rat kidney extracellular calcium/polyvalent cation-sensing receptor. Proc Natl Acad Sci U S A 1995; 92:131-5. [PMID: 7816802 PMCID: PMC42831 DOI: 10.1073/pnas.92.1.131] [Citation(s) in RCA: 372] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The maintenance of a stable extracellular concentration of ionized calcium depends on the integrated function of a number of specialized cells (e.g., parathyroid and certain kidney epithelial cells). We recently identified another G protein-coupled receptor (BoPCaRI) from bovine parathyroid that responds to changes in extracellular Ca2+ within the millimolar range and provides a key mechanism for regulating the secretion of parathyroid hormone. Using an homology-based strategy, we now report the isolation of a cDNA encoding an extracellular Ca2+/polyvalent cation-sensing receptor (RaKCaR) from rat kidney. The predicted RaKCaR protein shares 92% identity with BoPCaR1 receptor and features a seven membrane-spanning domain, characteristic of the G protein-coupled receptors, which is preceded by a large hydrophilic extracellular NH2 terminus believed to be involved in cation binding. RaKCaR cRNA-injected Xenopus oocytes responded to extracellular Ca2+, Mg2+, Gd3+, and neomycin with characteristic activation of inositol phospholipid-dependent, intracellular Ca(2+)-induced Cl- currents. In rat kidney, Northern analysis revealed RaKCaR transcripts of 4 and 7 kb, and in situ hybridization showed localization primarily in outer medulla and cortical medullary rays. Our results provide important insights into the molecular structure of an extracellular Ca2+/polyvalent cation-sensing receptor in rat kidney and provide another basis on which to understand the role of extracellular divalent cations in regulating kidney function in mineral metabolism.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Chlorides/metabolism
- Cloning, Molecular
- Female
- Gene Expression
- Gene Library
- In Situ Hybridization
- Kidney/metabolism
- Male
- Molecular Sequence Data
- Oocytes/physiology
- Organ Specificity
- Protein Structure, Secondary
- RNA, Complementary
- RNA, Messenger/analysis
- RNA, Messenger/biosynthesis
- Rats
- Rats, Sprague-Dawley
- Receptors, Calcium-Sensing
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/physiology
- Xenopus laevis
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research-article |
30 |
372 |
17
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Keyt BA, Nguyen HV, Berleau LT, Duarte CM, Park J, Chen H, Ferrara N. Identification of vascular endothelial growth factor determinants for binding KDR and FLT-1 receptors. Generation of receptor-selective VEGF variants by site-directed mutagenesis. J Biol Chem 1996; 271:5638-46. [PMID: 8621427 DOI: 10.1074/jbc.271.10.5638] [Citation(s) in RCA: 372] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Vascular endothelial growth factor (VEGF) expression in various cell types is induced by hypoxia and other stimuli. VEGF mediates endothelial cell proliferation, angiogenesis, vascular growth, and vascular permeability via the endothelial cell receptors, kinase insert domain-containing receptor (KDR)/fetal liver kinase 1 (Flk-1) and FLT-1. Alanine-scanning mutagenesis was used to identify a positively charged surface in VEGF that mediates binding to KDR/Flk-1. Arg82, Lys84 and His86, located in a hairpin loop, were found to be critical for binding KDR/Flk-1, while negatively charged residues, Asp63, Glu64, and Glu67, were associated with FLT-1 binding. A VEGF model based on PDGFb indicated these positively and negatively charged regions are distal in the monomer but are spatially close in the dimer. Mutations within the KDR site had minimal effect on FLT-1 binding, and mutants deficient in FLT-1 binding did not affect KDR binding. Endothelial cell mitogenesis was abolished in mutants lacking KDR affinity; however, FLT-1 deficient mutants induced normal proliferation. These results suggest dual sets of determinants in the VEGF dimer that cross-link cell surface receptors, triggering endothelial cell growth and angiogenesis. Furthermore, this mutational analysis implicates KDR, but not FLT-1, in VEGF induction of endothelial cell proliferation.
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MESH Headings
- Amino Acid Sequence
- Animals
- Binding Sites
- Binding, Competitive
- CHO Cells
- Cricetinae
- Endothelial Growth Factors/chemistry
- Endothelial Growth Factors/metabolism
- Endothelial Growth Factors/pharmacology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Enzyme-Linked Immunosorbent Assay
- Genetic Variation
- Immunoblotting
- Kinetics
- Liver/metabolism
- Lymphokines/chemistry
- Lymphokines/metabolism
- Lymphokines/pharmacology
- Macromolecular Substances
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Platelet-Derived Growth Factor/chemistry
- Point Mutation
- Protein Structure, Secondary
- Proto-Oncogene Proteins/metabolism
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptors, Growth Factor/metabolism
- Receptors, Vascular Endothelial Growth Factor
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Recombinant Proteins/pharmacology
- Sequence Homology, Amino Acid
- Transfection
- Vascular Endothelial Growth Factor A
- Vascular Endothelial Growth Factor Receptor-1
- Vascular Endothelial Growth Factors
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Comparative Study |
29 |
372 |
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Pollak MR, Brown EM, Estep HL, McLaine PN, Kifor O, Park J, Hebert SC, Seidman CE, Seidman JG. Autosomal dominant hypocalcaemia caused by a Ca(2+)-sensing receptor gene mutation. Nat Genet 1994; 8:303-7. [PMID: 7874174 DOI: 10.1038/ng1194-303] [Citation(s) in RCA: 346] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Defects in the human Ca(2+)-sensing receptor gene have recently been shown to cause familial hypocalciuric hypercalcaemia and neonatal severe hyperparathyroidism. We now demonstrate that a missense mutation (Glu128Ala) in this gene causes familial hypocalcaemia in affected members of one family. Xenopus oocytes expressing the mutant receptor exhibit a larger increase in inositol 1,4,5-triphosphate in response to Ca2+ than oocytes expressing the wild-type receptor. We conclude that this extracellular domain mutation increases the receptor's activity at low Ca2+ concentrations, causing hypocalcaemia in patients heterozygous for such a mutation.
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Park J, Karplus K, Barrett C, Hughey R, Haussler D, Hubbard T, Chothia C. Sequence comparisons using multiple sequences detect three times as many remote homologues as pairwise methods. J Mol Biol 1998; 284:1201-10. [PMID: 9837738 DOI: 10.1006/jmbi.1998.2221] [Citation(s) in RCA: 340] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sequences of related proteins can diverge beyond the point where their relationship can be recognised by pairwise sequence comparisons. In attempts to overcome this limitation, methods have been developed that use as a query, not a single sequence, but sets of related sequences or a representation of the characteristics shared by related sequences. Here we describe an assessment of three of these methods: the SAM-T98 implementation of a hidden Markov model procedure; PSI-BLAST; and the intermediate sequence search (ISS) procedure. We determined the extent to which these procedures can detect evolutionary relationships between the members of the sequence database PDBD40-J. This database, derived from the structural classification of proteins (SCOP), contains the sequences of proteins of known structure whose sequence identities with each other are 40% or less. The evolutionary relationships that exist between those that have low sequence identities were found by the examination of their structural details and, in many cases, their functional features. For nine false positive predictions out of a possible 432,680, i.e. at a false positive rate of about 1/50,000, SAM-T98 found 35% of the true homologous relationships in PDBD40-J, whilst PSI-BLAST found 30% and ISS found 25%. Overall, this is about twice the number of PDBD40-J relations that can be detected by the pairwise comparison procedures FASTA (17%) and GAP-BLAST (15%). For distantly related sequences in PDBD40-J, those pairs whose sequence identity is less than 30%, SAM-T98 and PSI-BLAST detect three times the number of relationships found by the pairwise methods.
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Comparative Study |
27 |
340 |
20
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Privman V, Goia DV, Park J, Matijevi&cacute E. Mechanism of Formation of Monodispersed Colloids by Aggregation of Nanosize Precursors. J Colloid Interface Sci 1999; 213:36-45. [PMID: 10191004 DOI: 10.1006/jcis.1999.6106] [Citation(s) in RCA: 337] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
It has been experimentally established in numerous cases that precipitation of monodispersed colloids from homogeneous solutions is a complex process. Specifically, it was found that in many systems nuclei, produced rapidly in a supersaturated solution, grow to nanosize primary particles (singlets), which then coagulate to form much larger final colloids in a process dominated by irreversible capture of these singlets. This paper describes a kinetic model that explains the formation of dispersions of narrow size distribution in such systems. Numerical simulations of the kinetic equations, with experimental model parameter values, are reported. The model was tested for a system involving formation of uniform spherical gold particles by reduction of auric chloride in aqueous solutions. The calculated average size, the width of the particle size distribution, and the time scale of the process agreed reasonably well with the experimental values. Copyright 1999 Academic Press.
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26 |
337 |
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Valenzuela DM, Stitt TN, DiStefano PS, Rojas E, Mattsson K, Compton DL, Nuñez L, Park JS, Stark JL, Gies DR. Receptor tyrosine kinase specific for the skeletal muscle lineage: expression in embryonic muscle, at the neuromuscular junction, and after injury. Neuron 1995; 15:573-84. [PMID: 7546737 DOI: 10.1016/0896-6273(95)90146-9] [Citation(s) in RCA: 333] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
While a number of growth factors have been described that are highly specific for particular cell lineages, neither a factor nor a receptor uniquely specific to the skeletal muscle lineage has previously been described. Here we identify a receptor tyrosine kinase (RTK) specific to skeletal muscle, which we term "MuSK" for muscle-specific kinase. MuSK is expressed at low levels in proliferating myoblasts and is induced upon differentiation and fusion. In the embryo, it is specifically expressed in early myotomes and developing muscle. MuSK is then dramatically down-regulated in mature muscle, where it remains prominent only at the neuromuscular junction; MuSK is thus the only known RTK that localizes to the neuromuscular junction. Strikingly, MuSK expression is dramatically induced throughout the adult myofiber after denervation, block of electrical activity, or physical immobilization. In humans, MuSK maps to chromosome 9q31.3-32, which overlaps with the region reported to contain the Fukuyama muscular dystrophy mutation. Identification of MuSK introduces a novel receptor-factor system that seems sure to play an important and selective role in many aspects of skeletal muscle development and function.
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30 |
333 |
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Yoon BH, Romero R, Park JS, Kim M, Oh SY, Kim CJ, Jun JK. The relationship among inflammatory lesions of the umbilical cord (funisitis), umbilical cord plasma interleukin 6 concentration, amniotic fluid infection, and neonatal sepsis. Am J Obstet Gynecol 2000; 183:1124-9. [PMID: 11084553 DOI: 10.1067/mob.2000.109035] [Citation(s) in RCA: 322] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE The purpose of this study was to determine whether funisitis (inflammation of the umbilical cord detected by histologic examination of the placenta) is associated with changes in the umbilical cord plasma concentration of interleukin 6, microbial invasion of the amniotic cavity, and neonatal sepsis. STUDY DESIGN The relationship among the presence of funisitis, interleukin 6 concentrations in umbilical cord plasma at birth, the results of amniotic fluid culture performed within 3 days of birth, and the occurrence of congenital neonatal sepsis was examined in 315 consecutive singleton preterm births (20-35 weeks' gestation). Funisitis was diagnosed in the presence of neutrophil infiltration into the umbilical vessel walls or Wharton jelly. The interleukin 6 concentration was measured with a specific immunoassay. Amniocentesis was performed in 106 patients within 3 days of birth. Amniotic fluid was cultured for aerobic and anaerobic bacteria and for mycoplasmas. RESULTS (1) Funisitis was present in 25% of patients (78/315). (2) Patients with funisitis had a significantly higher median cord plasma interleukin 6 and a lower gestational age at birth than did those without funisitis (cord interleukin 6: median, 52.4 pg/mL; range, 0.9-19,230 pg/mL; vs median, 4.6 pg/mL; range, 0-18,108 pg/mL; gestational age: median, 31.1 weeks' gestation; range, 21.0-35.0 weeks' gestation; vs median, 32.9 weeks' gestation; range, 21.4-35.0 weeks' gestation; P<.001 for each comparison). (3) A cord plasma interleukin 6 of > or =17.5 pg/mL had a sensitivity of 70% and a specificity of 78% in the identification of funisitis. (4) Microbial invasion of the amniotic cavity and clinical chorioamnionitis were more common among patients with funisitis than among those without funisitis (positive amniotic fluid culture: 53% [20/38]; vs. 12% [8/68]; clinical chorioamnionitis: 18% [14/78]; vs. 4% [9/237]; P<.001 for each comparison). (5) Neonates with funisitis had a significantly higher rate of congenital sepsis than did those without this lesion (12% [8/66] vs. 1% [3/216]; P<.001); this difference remained significant after adjustment for gestational age at birth (odds ratio, 7.2; 95% confidence interval, 1.8-29.0). CONCLUSION (1) Umbilical cord plasma interleukin 6 concentrations were higher in neonates born with funisitis than in those without this lesion. (2) Funisitis is associated with amniotic fluid infection, congenital neonatal sepsis, and the fetal inflammatory response syndrome.
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25 |
322 |
23
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Benns JM, Choi JS, Mahato RI, Park JS, Kim SW. pH-sensitive cationic polymer gene delivery vehicle: N-Ac-poly(L-histidine)-graft-poly(L-lysine) comb shaped polymer. Bioconjug Chem 2000; 11:637-45. [PMID: 10995206 DOI: 10.1021/bc0000177] [Citation(s) in RCA: 321] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Advancing biotechnology spurs the development of new pharmaceutically engineered gene delivery vehicles. Poly(L-histidine) ¿PLH¿ has been shown to induce membrane fusion at endosomal pH values, whereas PLL has a well documented efficacy in polyplex formation. Therefore, N-Ac-poly(L-histidine)-graft-poly(L-lysine) ¿PLH-g-PLL¿ was synthesized by grafting poly(L-histidine) to poly(L-lysine) ¿PLL¿. PLH-g-PLL formed polyplex particles by electrostatic interactions with plasmid DNA ¿pDNA¿. The mean particle size of the polyplexes was in the range of 117 +/- 6 nm to 306 +/- 77 nm. PLH-g-PLL gene carrier demonstrated higher transfection efficacy in 293T cells than PLL at all equivalent weight ratios with pDNA. The inclusion of chloroquine as an endosomolytic agent enhanced transfection for both PLL and PLH-g-PLL gene carriers. PLH-g-PLL enhanced beta-galactosidase expression compared to PLL, but still increased in efficacy when chloroquine was included.
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25 |
321 |
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Pitt B, Mancini GB, Ellis SG, Rosman HS, Park JS, McGovern ME. Pravastatin limitation of atherosclerosis in the coronary arteries (PLAC I): reduction in atherosclerosis progression and clinical events. PLAC I investigation. J Am Coll Cardiol 1995; 26:1133-9. [PMID: 7594023 DOI: 10.1016/0735-1097(95)00301-0] [Citation(s) in RCA: 318] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVES This study was designed to evaluate the effect of pravastatin on progression of coronary atherosclerosis and ischemic events in patients with coronary artery disease and mild to moderate hyperlipidemia. BACKGROUND Few clinical trial data support the use of lipid-lowering therapy in patients with coronary artery disease and mild to moderate elevations in cholesterol levels. METHODS Four hundred eight patients (mean age 57 years) with coronary artery disease and low density lipoprotein (LDL) cholesterol > or = 130 mg/dl (3.36 mmol/liter) but < 190 mg/dl ([4.91 mmol/liter]) despite diet were randomized in a 3-year study to receive pravastatin or placebo. Atherosclerosis progression was evaluated by quantitative coronary arteriography. RESULTS Baseline mean LDL cholesterol was 164 mg/dl (4.24 mmol/liter). Pravastatin decreased total and LDL cholesterol and triglyceride levels by 19%, 28% and 8%, respectively, and increased high density lipoprotein cholesterol by 7% (p < or = 0.001 vs. placebo for all lipid variables). Progression of atherosclerosis was reduced by 40% for minimal vessel diameter (p = 0.04), particularly in lesions < 50% stenosis at baseline. There was a consistent although not statistically significant effect on mean diameter and percent diameter stenosis. There were also fewer new lesions in those assigned pravastatin (p < or = 0.03). Myocardial infarction was reduced during active treatment (8 in the pravastatin group, 17 in the placebo group; log-rank test, p < or = 0.05; 60% risk reduction), with the benefit beginning to emerge after 1 year. CONCLUSIONS In patients with coronary artery disease and mild to moderate cholesterol elevations, pravastatin reduces progression of coronary atherosclerosis and myocardial infarction. The time course of event reduction increases the potential for a relatively rapid decrease in the clinical manifestations of coronary artery disease with lipid lowering.
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Clinical Trial |
30 |
318 |
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Prescott LF, Park J, Ballantyne A, Adriaenssens P, Proudfoot AT. Treatment of paracetamol (acetaminophen) poisoning with N-acetylcysteine. Lancet 1977; 2:432-4. [PMID: 70646 DOI: 10.1016/s0140-6736(77)90612-2] [Citation(s) in RCA: 314] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fifteen patients with paracetamol (acetaminophen) poisoning were treated with intravenous N-acetylcystein (300 mg/kg given over 20 h). Mean admission and 4 h plasma-paracetamol concentrations were 262 and 369 microgram/ml, respectively. Liver-function tests remained normal or were only slightly disturbed in 11 of 12 patients treated within 10 h of paracetamol ingestion. Severe liver damage developed in the other patient and in the three in whom treatment was started more than 10 h after paracetamol ingestion. In contrast to cysteamine, N-acetylcysteine was very well tolerated and has the advantage of being available as a pharmaceutical preparation in a 20% sterile solution.
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Comparative Study |
48 |
314 |