Biomedical subjects

Nan Li

Publications and source records attributed to Nan Li.

At least 109 records · Page 6Linked to original sources

PubMed2003

[Retrospective analysis of the corticosteroids treatment on severe acute respiratory syndrome (SARS)].

OBJECTIVE: To analyze the usage of corticosteroids in the treatment of SARS. METHODS: The usage of corticosteroids in 43 SARS patients were reviewed. The initial dosage and the highest dosage of prednisolone were investigated. RESULTS: According to the dosage of the early 3 days, the initial dosage was calculated. The initial methyprednisonlone dosage was (170.82 +/- 15.89) mg.d-1, from 48 to 500 mg.d-1. The maximal dosage was (291.44 +/- 37.63) mg.d-1 (48-800 mg.d-1). Four patients recovered without corticosteroides therapy. Initial therapy was kept in 25 cases. Two had hyperglycemia, one of whom died of hyperosmotic coma and renal failure. 14 cases were not responsive and needed to increase the dosage of corticosteroids. 9 of them accepted pulse dosage therapy and acquired good outcome. None in the group had significant side effect. The severity of patients of the two groups had no significant difference. Those of nonresponsiveness had higher dosage and needed longer time to reach stable. CONCLUSION: Sub-pulse dosage of methyprednisolone was effective for most SARS patients. Those who were less responsiveness might due to their poor sensitiveness to corticosteroids instead of SARS severity. Pulse treatment might be safe in carefully selected patients.

Adolescent↗

PubMed2003

[Plain radiograph and CT features of 112 patients with SARS in acute stage].

OBJECTIVE: To retrospectively analyze the X-ray and CT features of patients with suggestive of SARS at the early stages. METHODS: The study comprised 112 patients (43 men, 69 women; aged from 16 to 82 year) with clinically proved SARS. Chest radiograph was performed in all the patients and CT of thorax in 22 patients during the first week of the onset. RESULTS: In the early stage, the most common findings were patchy ground-glass opacification (GGO) (79.5% on X-ray and 81. 8% on CT) and mixed lesions of GGO with irregular consolidation (21.4% on X-ray and 45.5% on CT) and/or granulomas (14.3% on X-ray and 27.3% on CT). A majority of lesions were located in the middle and lower field (70.9%) with peripheral distribution (69%). Other findings on CT included intralobular and interlobular septal thickening (carzy-paving pattern) (36.4%), bronchiectasis (18.2%) and small pleural effusion (22.7%). CONCLUSION: Common radiologic findings of SARS are ground-glass opacification and mixed lesions of GGO with irregular consolidation and/or granulomas and lower location and peripheral distribution.

Adolescent↗

PubMed2003

[Dynamic observation of the features of chest radiograph in SARS patients].

OBJECTIVE: To observe the radiological features of chest X ray in SARS patients. METHODS: The chest films of 23 cases of SARS were reviewed in the study. The chest film features and site of lung involvement were studied in early stage, most severe stage and recovery stage. The sequential chest film were evaluated hemiquantitatively. The correlation between the score of lung involvement and clinical course was also studied. RESULTS: The lung involvement was most common in lower lung field and outer zone both in early and acute stage. 91.3% cases had bilateral involvement and 91.2% had multifield involvement (two lung fields involvement is 47.8%, three and four lung fields involvement are both 21.7%). The ill-defined and variable opacities showed to be dominant. The improvement of acute stage lesion in 17 cases is related to the usage and increased dosage of corticosteroid, some cases showed non-parallel with symptom and chest X-ray. Hemiquantitative analysis showed there are 6 cases had second peak in X ray, the mean time of onset is 13.2 days, and lasted for 5.8 days. CONCLUSION: The chest X ray of SARS has some features and its changes can reflect the clinical situation.

Adult↗

PubMed2003

[Clinical observation of non-invasive positive pressure ventilation (NIPPV) in the treatment of severe acute respiratory syndrome (SARS)].

OBJECTIVE: To observe the application and the roles of non-invasive positive pressure ventilation (NIPPV) in the treatment of severe acute respiratory syndrome (SARS). METHODS: To analyze retrospectively the data of NIPPV in 105 SARS cases hospitalized from 8 Apr to 14 May, 2003. To generalize the indication, parameter adjustment, treatment effects, side effects and affection rate of the medical faculty. RESULTS: The total number of the patients was 105. Among them 24 patients accepted NIPPV, 5 patients died. The mortality was 4.7%, which was lower than the average rate of our country. The most common side effect was subcutaneous emphysema, of which the incidence rate was 16.7%. There was no SARS affected among the medical faculty during the course of NIPPV. CONCLUSION: NIPPV is a safe and effective method for the treatment of the severe SARS. The proper application of NIPPV could decrease the chance of the invasive ventilation and decrease the affective rate of the medical faculty.

Adolescent↗

PubMed2003

Cloning and functional characterization of human septin 10, a novel member of septin family cloned from dendritic cells.

Septins are a family of cytoskeletal proteins with GTPase activity involved in various cellular biological processes. Here, we describe the identification of septin 10, a novel septin family member from human dendritic cells. The 3018-bp full-length cDNA potentially encodes a 517-residue peptide, sharing closest homology to human septin 8 and septin 6. With a conserved GTP-binding motif at its N-terminus, septin 10 protein can bind to GTP and exert GTPase activity. Human septin 10 gene is electronically mapped to 8q11.2-12. It is ubiquitously expressed in normal tissues, with the abundant expression in heart and kidney, placenta, skeletal muscles, liver and lung, as well as various tumor cell lines. Interestingly, dendritic cells express upregulated septin 10 upon LPS-induced maturation. Based on its GFP-fusion protein, septin 10 is found to localize in cytoplasm and nucleus, with a subcellular pattern independent of the filamentous state of actin.

Amino Acid Sequence↗

PubMed2003

Rab39, a novel Golgi-associated Rab GTPase from human dendritic cells involved in cellular endocytosis.

Rab GTPases are Ras-like small molecular weight GTP binding proteins that are involved in various steps along the exocytic and endocytic pathways. Here we report that Rab39, a novel Rab protein, is a Golgi-associated protein involved in endocytosis of HeLa cells. Full-length cDNA of Rab39 contains 1251bp with an open reading frame (ORF) of 636bp, which is predicted to encode a 211 aa protein. By blast analysis of Rab39 cDNA and protein sequence with homologues, we find that Rab39 may be a short variant of Rab34. Rab39 contains conserved motifs involved in phosphate/guanosine binding and a microbody C-terminal targeting signal. RT-PCR analysis indicates that Rab39 is mainly detected in epithelial cell lines, and Northern blot analysis shows that Rab39 is expressed ubiquitously in human tissues. By using FITC-BSA as an endocytic tracer, we show that Rab39 can facilitate endocytosis in HeLa cells when expressed either transiently or stably. Confocal microscopy examination of Rab39 subcellular localization suggests that Rab39 is associated with Golgi-associated organelles. Our findings demonstrate that Rab39 is a novel Rab GTPase involved in cellular endocytosis.

3T3 Cells↗

PubMed2003

Cloning and identification of a novel ubiquitin-like protein, BMSC-UbP, from human bone marrow stromal cells.

Ubiquitin is one of phylogenetically well-conserved proteins in all eukaryotes. Ubiquitin-dependent modification of protein contributes to fine regulation of cellular biological processes. Using large-scale screening of human bone marrow stromal cell (BMSC) cDNA library, we isolated a full-length cDNA of 1352 bp encoding 380 amino acids with a ubiquitin domain (UBQ), which was designed as bone marrow stromal cell-derived ubiquitin-like protein (BMSC-UbP). In addition to UBQ domain at its N-terminus, BMSC-UbP also possesses a ubiquitin-associated domain at its C-terminus, sharing moderate homology to some ubiquitin-like proteins such as UBIN, Chap1, and ubiquilin. BMSC-UbP localizes at chromosome 15q22.3-q23 as confirmed by blast search in human genome. BMSC-UbP mRNA is widely expressed in human multiple tissues and various tumor cell lines. Moreover, BMSC-UbP mRNA decreased in BMSC stimulated with PMA and increased in HL60 cells stimulated with LPS, suggesting that BMSC-UbP might play roles in regulation of BMSC function or cell differentiation through an evocator- and cell-specific pattern.

Amino Acid Sequence↗

PubMed2003

Cloning and functional characterization of GNPI2, a novel human homolog of glucosamine-6-phosphate isomerase/oscillin.

The enzyme, glucosamine-6-phosphate isomerase (GNPI) or deaminase (GNPDA) (EC 5.3.1.10), catalyzes the conversion of GNP to fructose-6-phosphate and ammonia, with an aldo/keto isomerization and an amination/deamination. A hamster sperm-derived protein (Oscillin) with high similarity to bacterial GNPI has been proved to be capable of inducing calcium oscillation in eggs at fertilization. GNPI/Oscillin was supposed to be an important factor in starting embryonic development. From the cDNA library of human dendritic cells (DC), we isolated a novel full-length cDNA encoding a 276-amino acid-residue protein that shares high homology with human GNPI/Oscillin. So, the novel molecule is named as GNPI2. The GNPI2 gene consists of seven exons and six introns. It is mapped to chromosome 4. Northern blot analysis indicated that the tissue distribution of GNPI2 mRNA is different from that of human GNPI or Oscillin mRNA. GNPI2 is ubiquitously expressed in most of human tissues with high expression in testis, ovary, placenta, and heart. Like GNPI, the recombinant GNPI2 has been proved to have the enzymatic activity to catalyze the conversion of GNP to fructose-6-phosphate. Our results indicated that GNPI2 is a novel protein with definite function as a GNPI.

Aldose-Ketose Isomerases↗

PubMed2003

Molecular cloning and characterization of a novel cystatin-like molecule, CLM, from human bone marrow stromal cells.

The cystatins are physiological cysteine proteinase inhibitors. Here we report the cloning of a novel human cystatin-like molecule (CLM) from human bone marrow stromal cell (BMSC) cDNA library. The putative CLM protein contained 159 residues with a 29-residue signal peptide. CLM protein was highly homologous to family 2 cystatins, especially mouse and human testatin. The CLM gene spanned two exons and was mapped on chromosome 20p11.2, among cystatin superfamily gene clusters. CLM mRNA was barely detected in most tumor cell lines except for breast adenocarcinoma MCF-7 cells and glioblastoma U251 cells, but after LPS or PMA stimulation, CLM expression was increased in myelogenous leukemia cell lines HL-60 and U-937. Northern blot analysis revealed CLM was ubiquitously expressed in normal tissues, which was clearly different from the testis-specific expression pattern of most family 2 cystatins. When overexpressed in 293 cells, GFP-fused CLM targeted extracellularly through secretory pathway by Golgi apparatus. The results indicated that the secreted CLM protein might play roles in hematopoietic differentiation or inflammation.

Adult↗

PubMed2003

Cloning and identification of a novel human ubiquitin-like protein, DC-UbP, from dendritic cells.

Several ubiquitin-like proteins recently discovered have been confirmed to modify proteins akin to ubiquitinization for fine-regulation of intracellular proteins. In the present study, we report a novel ubiquitin-like protein from human dendritic cells (DC), named as dendritic cell-derived ubiquitin-like protein (DC-UbP). The full-length of DC-UbP cDNA is 565bp and encodes 106 amino acids. Ubiquitin domain (UBQ) in DC-UbP shares 28.6% identity and 55% similarity to ubiquitin, but does not possess the conserved C-terminus Gly-Gly of ubiquitin required for ubiquitinization. DC-UbP localized in cytoplasm, especially in mitochondrion, indicating that it may play a role in mitochondrial biology. DC-UbP mRNA was expressed in various tumor cells, but not in adult human normal tissues, suggesting that DC-UbP might be related to tumor genesis. In addition, DC-UbP mRNA expression decreased in the HL60 cells undergoing apoptosis after being stimulated with TRAIL and in the differentiated HL60 cells induced by ARTA. Taken together, DC-UbP might be downregulated during cellular differentiation and apoptosis.

Amino Acid Sequence↗

PubMed2003

A motif rich in charged residues determines product specificity in isomaltulose synthase.

Isomaltulose synthase (PalI) catalyzes hydrolysis of sucrose and formation of alpha-1,6 and alpha-1,1 bonds to produce isomaltulose (alpha-D-glucosylpyranosyl-1,6-D-fructofranose) and small amount of trehalulose (alpha-D-glucosylpyranosyl-1,1-D-fructofranose). A potential isomaltulose synthase-specific motif ((325)RLDRD(329)), that contains a 'DxD' motif conserved in many glycosyltransferases, was identified based on sequence comparison with reference to the secondary structural features of PalI and homologs. Site-directed mutagenesis analysis of the motif showed that the four charged amino acid residues (Arg(325), Arg(328), Asp(327) and Asp(329)) influence the enzyme kinetics and determine the product specificity. Mutation of these four residues increased trehalulose formation by 17-61% and decreased isomaltulose by 26-67%. We conclude that the 'RLDRD' motif controls the product specificity of PalI.

Amino Acid Motifs↗

PubMed2003

Monocyte lipid rafts contain proteins implicated in vesicular trafficking and phagosome formation.

Lipid rafts are membrane microdomains of unique lipid composition that segregate proteins with poorly understood consequences for membrane organization. Identification of raft associated proteins could therefore provide novel insight into raft-dependent functions. Monocytes process antigens for presentation to T cells by ingesting pathogens into calcium-dependent plasma membrane invaginations called "phagosomes" which develop by sequential fusion with the endoplasmic reticulum, early and late endosomes. We investigated the protein composition of Triton X-100 insoluble low density membranes of the monocyte cell-line THP-1 by matrix-assisted laser desorption/ionization-time of flight and tandem mass spectrometry. The ganglioside GM1 colocalized on the plasma membrane with the raft markers flotillin 1 and 2, which were enriched in low buoyant density fractions containing 52 identifiable proteins, 28 of which have not been reported in rafts, and nine of which are associated with the endoplasmic reticulum (ER). Remarkably, 27 of the 52 proteins are components of phagosomes, including the ER protein calnexin which we demonstrate is phosphorylated on serine 562, a switch controlling calcium homeostasis. The presence of the early and late endosome trafficking proteins Rab-1, and Rab-7 together with the late endosome protein LIMPII, indicate lipid rafts are present throughout endosome maturation. Identification of vacuolar ATP synthase, and synaptosomal-associated protein-23, proteins implicated in membrane fusion, together with the cytoskeletal proteins actin, alpha-actinin, and vimentin, and Rac 1, 2, and 3, regulators of cytoskeletal assembly, indicate monocyte lipid rafts contain the machinery to direct vesicular fusion and actin based vesicular migration throughout phagosome development.

Biological Transport, Active↗

PubMed2003

Glutamine supports recovery from loss of transepithelial resistance and increase of permeability induced by media change in Caco-2 cells.

Recent evidence suggests that the conditionally essential amino acid glutamine is important for intestinal barrier function. However, the mechanism remains undefined. To determine the effects of glutamine on permeability of intestinal epithelial cell monolayers, Caco-2 cells were grown on membrane filters and exposed to 4 mmol/L sodium butyrate in order to rapidly achieve high levels of alkaline phosphatase and high transepithelial resistance as seen in functionally mature enterocytes. A standard method of medium exchange consisting of removal and replacement resulted in a catastrophic loss of transepithelial resistance and increase of mannitol and dextran fluxes that required 2-4 hrs and protein synthesis to recover. The effect was attributed to exposure of the upper monolayer surface to atmosphere and could be avoided by refeeding by incremental perfusion. Spontaneously-differentiated Caco-2 monolayers were resistant to this stress. This novel stress test was employed as a sensitive assay for the requirement of glutamine for monolayer transepithelial resistance and mannitol permeability. Pre-stress glutamine availability was more important than Gln-availability during the recovery phase. Thus the transepithelial resistance and permeability of butyrate-induced monolayers is dynamically-regulated in response to atmospheric exposure, by a mechanism that depends on threshold levels of glutamine availability.

Alkaline Phosphatase↗

PubMed2003

Glutamine decreases lipopolysaccharide-induced IL-8 production in Caco-2 cells through a non-NF-kappaB p50 mechanism.

Glutamine (Gln) supplementation has been shown to decrease production of pro-inflammatory cytokines by the human intestinal mucosa. The mechanism of this is poorly understood. We hypothesize that Gln down-regulates lipopolysaccharide (LPS)-stimulated pro-inflammatory cytokine production in Caco-2 cells by nuclear factor-kappa B (NF-kappaB). Caco-2 cells were incubated with different concentrations of Gln with or without methionine sulfoximine (MS, an inhibitor of glutamine synthetase) before stimulation with LPS. IL-6, IL-8, IL-10 and TNF-alpha protein and mRNA level were determined. NF-kappaB translocation was determined using an ELISA-based kit. IL-8 was the only detectable cytokine/chemokine. The largest amount of IL-8 was secreted by cells in the presence of MS with no Gln in the medium after exposure to LPS. LPS increased IL-8 production, peaking 10h after LPS administration. The addition of Gln (0.5 or 5.0mM) decreased IL-8 peptide and mRNA expression. LPS increased NF-kappaB nuclear translocation in the presence or absence of MS. Neither Gln nor MS altered NF-kappaB nuclear translocation. These results indicate that the lack of glutamine increases IL-8 production by Caco-2 cells after LPS stimulation. However, the glutamine-mediated decrease in LPS-stimulated IL-8 production is not associated with NF-kappaB p50 nuclear binding.

Caco-2 Cells↗

PubMed2003

Recurrent nonstatus generalized seizures alter the developing chicken brain.

PURPOSE: Noninvasive magnetic resonance imaging was used to assess the evolution of seizure-induced pathology in epileptic, carrier, and normal chickens. Our objective was to determine whether repetitively evoked seizures in an epileptic fowl model of generalized seizures resulted in altered brain development. METHODS: Data were obtained from seizure and control groups at 45, 90, and 180 days after hatching. RESULTS: At 180 days, apparent diffusion coefficient (ADC) values in the optic tectum and archistriatum of the stimulated epileptic chicks were reduced, whereas ADC values in the nonstimulated group remained unchanged. The mean brain volume of epileptic chickens from the stimulated group was smaller than that from the nonstimulated group at 90 and 180 days. CONCLUSIONS: These findings establish that recurrent seizures modify the brain matrix.

Age Factors↗

PubMed2003

Bioactive triterpenoids from Symplocos chinensis.

A new triterpenoid, 2beta,3beta,19alpha,24-tetrahydroxy-23-norurs-12-en-28-oic acid (4), together with three known triterpenoids 3-oxo-19alpha,23,24-trihydroxyurs-12-en-28-oic acid (1), 2alpha,3beta,19alpha,23-tetrahydroxyurs-12-en-28-oic acid (2), 2alpha,3alpha,19alpha,23-tetrahydroxyurs-12-en-28-oic acid (3), was isolated from the roots of Symplocos chinensis. The new triterpenoid shows significant cytotoxic activity against B16 and BGC-823 cells.

Antineoplastic Agents↗

PubMed2003

Glutamine and barrier function in cultured Caco-2 epithelial cell monolayers.

Dietary glutamine (Gln) has been shown to be important for maintenance of the intestinal barrier. To investigate the role of the epithelium in this Gln dependence, Caco-2 cells were raised on semipermeable membranes under conditions that model different regions of the crypt and villus. Gln availability was controlled by addition to the medium and treatment with methionine sulfoximine to inhibit Gln synthetase (GS). Barrier function was assayed by measuring transepithelial electrical resistance and fluxes of [(14)C]mannitol and fluorescein isothiocyanate-dextran. The barrier function of these monolayers was found to require the Gln provided either in the medium at the apical or basal surface or via GS. However, the barrier was no more sensitive to Gln deprivation than it was to accumulation or maintenance of total protein. These results suggest that the in vivo dependence of the gut mucosal barrier on Gln likely involves roles separate from maintenance of the epithelial barrier per se.

Caco-2 Cells↗

PubMed2003

Relationship between the imaging features and pathologic alteration in hepatoma of rats.

AIM: The imaging features of MRI and DSA, using the models of implanted and induced hepatoma, were investigated in rats. METHODS: CBRH3 cancer cells were implanted for different liver site of rat liver and the diethylnitrosoamine was given orally to rats in order to induce liver cancer. Both experimental groups were detected by magnetic resonance imaging (MRI), digital subtraction angiography (DSA) and morphologic assay. RESULTS: Hypointensity on T1WI and homogenous high signal intensity on T2WI in MRI, and ring-like abnormal stain on DSA were found in implanted cancer. Induced cancers appeared as homogeneous or heterogeneous hypointensity on T1WI (10 cases), and equal or slight high intensity on T2WI (8 cases), but some as hypointensity on T2WI (2 cases). CONCLUSION: The imaging features of implanted cancers were similar to that of human liver metastases. Therefore, it could serve as an experimental model of human liver metastatic tumor. The imaging feature of induced cancers, whereas, were similar to that of human primary liver cancer. It could be use as an experimental model of human primary liver cancer.

Alkylating Agents↗