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Biomedical subjects

L Ni

Publications and source records attributed to L Ni.

At least 19 recordsLinked to original sources
PubMed2006

Direct effects of dexamethasone on human podocytes.

Glucocorticoids are widely used in the treatment of human glomerular diseases, but their mode of action is poorly understood particularly in steroid-sensitive nephrotic syndrome, which is most common in childhood and is characterized by a lack of inflammation in the kidney. The podocyte is a key cell in the glomerulus in health and disease: until recently, human podocytes have been difficult to study in vitro. We have developed a conditionally immortalized human podocyte cell line transfected with a temperature-sensitive simian virus 40 transgene: when the transgene is inactivated in vitro, these cells adopt the phenotype of differentiated podocytes. We have used these cells to evaluate, using immunocytochemistry, reverse transcriptase-polymerase chain reaction, and Western blotting, direct effects of the glucocorticoid dexamethasone at concentrations designed to mimic in vivo therapeutic corticosteroid levels. Dexamethasone upregulated expression of nephrin and tubulin-alpha, and downregulated vascular endothelial growth factor. Effects on cell cycle were complex with downregulation of cyclin kinase inhibitor p21 and augmentation of podocyte survival, without any effect on apoptosis. We report cytokine production by human podocytes, especially interleukin (IL)-6 and -8; IL-6 expression was suppressed by dexamethasone. These potent direct effects on podocytes illustrate a novel mode of action of glucocorticoids and suggest potential new therapeutic strategies for glomerular disease.

Antigens, Polyomavirus Transforming↗
PubMed2006

Conditionally immortalized human glomerular endothelial cells expressing fenestrations in response to VEGF.

Glomerular endothelial cells (GEnC) are specialized cells with important roles in physiological filtration and glomerular disease. Despite their unique features, GEnC have been little studied because of difficulty in maintaining them in cell culture. We have addressed this problem by generation of conditionally immortalized (ci) human GEnC using technology with which we have previously produced ci podocytes. Primary culture GEnC were transduced with temperature-sensitive simian virus 40 large tumour antigen and telomerase using retroviral vectors. Cells were selected, cloned, and then characterized by light and electron microscopy (EM), response to vascular endothelial growth factor (VEGF), and tumour necrosis factor (TNF)alpha, expression of endothelial markers by focused gene array, immunofluorescence and Western blotting, and formation and behaviour of monolayers. CiGEnC proliferated at the permissive temperature (33 degrees C) and became growth arrested at the non-permissive temperature (37 degrees C). CiGEnC retained morphological features of early-passage primary culture GEnC up to at least p41, confirming successful immortalization. EM demonstrated fenestrations, increased in number by VEGF. mRNA analysis confirmed expression of the endothelial markers platelet endothelial cell adhesion molecule 1, intercellular adhesion molecule 2, VEGF receptor 2, and von Willebrand factor, validated by immunofluorescence and Western blotting. CiGEnC also expressed Tie2, and TNFalpha upregulated E-selectin. CiGEnC formed monolayers with barrier properties responsive to cyclic adenosine 3',5' monophosphate (cAMP) and thrombin. CiGEnC retain the markers and behaviour of primary culture GEnC. They express fenestrations which are upregulated in response to VEGF. These cells are a unique resource for further study of GEnC and their roles in glomerular filtration, glomerular disease, and response to glomerular injury.

Biomarkers↗
PubMed2005

The Mouse Genome Database (MGD): from genes to mice--a community resource for mouse biology.

The Mouse Genome Database (MGD) forms the core of the Mouse Genome Informatics (MGI) system (http://www.informatics.jax.org), a model organism database resource for the laboratory mouse. MGD provides essential integration of experimental knowledge for the mouse system with information annotated from both literature and online sources. MGD curates and presents consensus and experimental data representations of genotype (sequence) through phenotype information, including highly detailed reports about genes and gene products. Primary foci of integration are through representations of relationships among genes, sequences and phenotypes. MGD collaborates with other bioinformatics groups to curate a definitive set of information about the laboratory mouse and to build and implement the data and semantic standards that are essential for comparative genome analysis. Recent improvements in MGD discussed here include the enhancement of phenotype resources, the re-development of the International Mouse Strain Resource, IMSR, the update of mammalian orthology datasets and the electronic publication of classic books in mouse genetics.

Animals↗
PubMed2005

Bacterial signal peptide recognizes HeLa cell mitochondrial import receptors and functions as a mitochondrial leader sequence.

Phage display was used to identify new components of the mammalian mitochondrial receptor complex using Tom20 as a binding partner. Two peptides were identified. One had partial identity (SMLTVMA) with a bacterial signal peptide from Toho-1, a periplasmic protein. The other had partial identity with a mitochondrial inner membrane glutamate carrier. The bacterial signal peptide could carry a protein into mitochondria both in vivo and in vitro. The first six residues of the sequence, SMLTVM, were necessary for import but the two adjacent arginine residues in the 30-amino-acid leader were not critical for import. The signal peptides of Escherichia coli beta-lactamase and Bacillsus subtilis lipase could not carry proteins into mitochondria. Presumably, the Toho-1 leader can adopt a structure compatible for recognition by the import apparatus.

Amino Acid Sequence↗
PubMed2005

Skewed T-cell receptor BV14 and BV16 expression and shared CDR3 sequence and common sequence motifs in synovial T cells of rheumatoid arthritis.

T-lymphocytes play an important role in rheumatoid arthritis (RA). In this study, we evaluated the hypothesis that common T-cell receptor (TCR) structural features may exist among infiltrating T cells of different RA patients, if the TCR repertoire is shaped by interaction with common self or microbial antigens in the context of susceptible HLA genes in RA. Synovial lesion tissue (ST), synovial fluid (SF) and blood specimens from RA patients and controls were analyzed for TCR V gene repertoire by real-time PCR. There was highly skewed BV14 and BV16 usage in synovial T cells of RA as opposed to those of controls, which was accompanied with a trend for correlation between skewed BV16 and DRB1(*)0405. Immunoscope analysis of the V-D-J region of ST-derived T cells demonstrated oligoclonal and polyclonal expansion of BV14(+) and BV16(+) T cells. Detailed characterization using specific BV and BJ primers further revealed common clonotypes combining the same BV14/BV16, BJ and CDR3 length. DNA cloning and sequence analysis of the clonotypes confirmed identical CDR3 sequences and common CDR3 sequence motifs among different RA patients. The findings are important in the understanding of BV gene skewing and CDR3 structural characteristics among synovial infiltrating T cells of RA.

Arthritis, Rheumatoid↗
PubMed2004

The Gene Ontology (GO) database and informatics resource.

The Gene Ontology (GO) project (http://www. geneontology.org/) provides structured, controlled vocabularies and classifications that cover several domains of molecular and cellular biology and are freely available for community use in the annotation of genes, gene products and sequences. Many model organism databases and genome annotation groups use the GO and contribute their annotation sets to the GO resource. The GO database integrates the vocabularies and contributed annotations and provides full access to this information in several formats. Members of the GO Consortium continually work collectively, involving outside experts as needed, to expand and update the GO vocabularies. The GO Web resource also provides access to extensive documentation about the GO project and links to applications that use GO data for functional analyses.

Animals↗
PubMed2004

The Mouse Genome Database (MGD): integrating biology with the genome.

The Mouse Genome Database (MGD) is one component of the Mouse Genome Informatics (MGI) system (http://www.informatics.jax.org), a community database resource for the laboratory mouse. MGD strives to provide a comprehensive knowledgebase about the mouse with experiments and data annotated from both literature and online sources. MGD curates and presents consensus and experimental data representations of genetic, genotype (sequence) and phenotype information including highly detailed reports about genes and gene products. Primary foci of integration are through representations of relationships between genes, sequences and phenotypes. MGD collaborates with other bioinformatics groups to curate a definitive set of information about the laboratory mouse and to build and implement the data and semantic standards that are essential for comparative genome analysis. Recent developments in MGD discussed here include an extensive integration of the mouse sequence data and substantial revisions in the presentation, query and visualization of sequence data.

Animals↗
PubMed2001

Antioxidants N-acetylcysteine (NAC) and 2-mercaptoethanol (2-ME) affect the survival and differentiative potential of cholinergic precursors from the embryonic septal nuclei and basal forebrain: involvement of ras signaling.

We investigated the effects of antioxidants N-acetylcysteine (NAC) and 2-mercaptoethanol (2-ME) on the expression of choline acetyltransferase (ChAT) in cultured cholinergic precursors from the embryonic rat septal nuclei and basal forebrain. Carboxy-dichlorofluorescein fluorescence confirmed that 2-ME inhibited intracellular oxidation. Low micromolar concentrations of 2-ME produce as much as a 12-fold increase in ChAT; this is enhanced further by inclusion of nerve growth factor (NGF). NAC effects are biphasic: 0.15 mM produces profound increases in ChAT while 1.5 mM has no effect. Immature (E16) cultures respond with increases in ChAT while more highly differentiated cultures (E18) do not. Labeling of single precursors with a lacZ-expressing retrovirus reveals that the increase in ChAT is due primarily to an increased number and size of clones, not an increase in cholinergic neurons per clone, suggesting an effect on precursor survival. Inhibition of ras farnesylation inhibits both 2-ME and NAC induction of ChAT suggesting a ras-mediated pathway. Inclusion of the MEK inhibitor PD98059 does not affect low doses of NAC, but at doses of NAC that fail to increase ChAT activity, inhibition of the pathway actually raises ChAT. Immunocytochemical investigation of the cultures indicates that cells exposed to low doses of NAC develop healthy neuronal arbors in the apparent absence of glial support. At higher concentrations of NAC, neurons were found in association with astrocytes, making contact via elaborate varicose fibers. Treatment of the cultures with PD98059 to inhibit MEK returned cultures to a 'low-dose' phenotype. These data suggest that redox status of basal forebrain precursors affect both their survival and differentiative potential.

Acetylcysteine↗
PubMed2001

Regional cerebral blood flow effects of nicotine in overnight abstinent smokers.

BACKGROUND: Most people agree that dependence to tobacco is mediated by the effects of nicotine on the central nervous system, albeit the neural pathways involved are not clearly delineated. We investigated the effect of nasal nicotine spray on regional cerebral blood flow (rCBF) in a sample of habitual smokers, with H2 15O and positron emission tomography (PET). METHODS: Eighteen volunteer smokers were studied after 12 hours of smoking deprivation. Regional cerebral blood flow measures were obtained with PET and 50 mCi H2 15O in six consecutive scans. Nicotine spray and a placebo spray were administered in a single-blind design, preceded and followed by baseline studies. Images were coregistered and anatomically standardized. Square (9-mm side) regions of interest were placed in 10 preselected brain regions, bilaterally. The effects of the experimental condition and gender were tested with two-way repeated-measures analysis of variance in each of the regions studied. RESULTS: Nicotine reduced rCBF in the left anterior temporal cortex and in the right amygdala. Increases were noted in the right anterior thalamus. CONCLUSIONS: In habitual smokers after overnight abstinence, nicotine induced differing effects on regional blood flow relative to whole brain blood flow. Increases were observed in the thalamus, a region rich in nicotinic receptors, and reductions in limbic and paralimbic (amygdala, anterior temporal cortex) regions.

Adolescent↗
PubMed2001

Phase I study of a third-generation selective estrogen receptor modulator, LY353381.HCL, in metastatic breast cancer.

PURPOSE: We conducted this phase I trial to determine the safety and toxicity profile of LY353381.HCl-a novel, potent, third-generation selective estrogen receptor modulator (SERM)-because this benzothiophene derivative demonstrated an SERM profile in preclinical studies. PATIENTS AND METHODS: We studied 32 patients with recurrent or metastatic breast cancer. Patients were treated in four cohorts with oral daily doses of 10, 20, 50, and 100 mg. Pharmacokinetic sampling was performed during the first 72 hours following the first dose on day 1 and during the 24 hours after the day 57 dose. Eligibility criteria included Eastern Cooperative Oncology Group performance status of 0 to 2; no significant major organ dysfunction; and at least 3 weeks elapsed since most recent hormonal therapy, chemotherapy, and estrogen replacement therapy. RESULTS: The median patient age was 56 years (range, 30 years to 76 years). The median number of prior chemotherapies for metastatic disease was one (range, zero to four), while the median number of prior hormone regimens for metastatic disease was two (range, zero to five). Receptor status was estrogen receptor (ER) positive and progesterone receptor (PR) positive, 19 patients; ER positive and PR negative, eight patients; ER positive and PR unknown, two patients; and ER and PR unknown, three patients. Dose-limiting toxicity was not observed. Treatment was well tolerated with mild to moderate hot flashes in 18 of 32 patients (56%) at all dose levels. Transvaginal ultrasound performed at baseline and after 12 weeks of treatment showed no endometrial thickening. Of the 32 patients evaluable for response, six patients had stable disease for at least 6 months with a median duration of 7.7 months (range, 6.2 months to 33.8 months). The pharmacokinetics of LY353381.HCl were generally linear with respect to time and studied dose range. CONCLUSION: As predicted in preclinical testing, daily oral LY353381.HCl is safe, is well tolerated at all tested dose levels, and may be clinically beneficial in patients with extensively pretreated metastatic breast cancer. Further studies with LY353381 to evaluate the efficacy in patients with or without prior exposure to tamoxifen and fewer overall prior regimens are under way.

Actuarial Analysis↗
PubMed2001

A genomic study of the bipolar bud site selection pattern in Saccharomyces cerevisiae.

A genome-wide screen of 4168 homozygous diploid yeast deletion strains has been performed to identify nonessential genes that participate in the bipolar budding pattern. By examining bud scar patterns representing the sites of previous cell divisions, 127 mutants representing three different phenotypes were found: unipolar, axial-like, and random. From this screen, 11 functional classes of known genes were identified, including those involved in actin-cytoskeleton organization, general bud site selection, cell polarity, vesicular transport, cell wall synthesis, protein modification, transcription, nuclear function, translation, and other functions. Four characterized genes that were not known previously to participate in bud site selection were also found to be important for the haploid axial budding pattern. In addition to known genes, we found 22 novel genes (20 are designated BUD13-BUD32) important for bud site selection. Deletion of one resulted in unipolar budding exclusively from the proximal pole, suggesting that this gene plays an important role in diploid distal budding. Mutations in 20 other novel BUD genes produced a random budding phenotype and one produced an axial-like budding defect. Several of the novel Bud proteins were fused to green fluorescence protein; two proteins were found to localize to sites of polarized cell growth (i.e., the bud tip in small budded cells and the neck in cells undergoing cytokinesis), similar to that postulated for the bipolar signals and proteins that target cell division site tags to their proper location in the cell. Four others localized to the nucleus, suggesting that they play a role in gene expression. The bipolar distal marker Bud8 was localized in a number of mutants; many showed an altered Bud8-green fluorescence protein localization pattern. Through the genome-wide identification and analysis of different mutants involved in bipolar bud site selection, an integrated pathway for this process is presented in which proximal and distal bud site selection tags are synthesized and localized at their appropriate poles, thereby directing growth at those sites. Genome-wide screens of defined collections of mutants hold significant promise for dissecting many biological processes in yeast.

Actins↗
PubMed2001

[The relationship among plasma soluble vascular cell adhesion molecule-1 level, airway responsiveness and blood eosinophil cationic protein in asthmatics with remission at least 3 years].

OBJECTIVE: To study the mechanism of asthma remission. The plasma soluble vascular cell adhesion molecule-1 (sVCAM-1), airway responsiveness (PC20) and other relative factors were measured in asthmatics with remission at least 3 years and compared with healthy controls. METHODS: Group I (asthmatics with remission at puberty): 20 cases including 11 males and 9 females, mean age of 21 years. All of the patients were definitely diagnosed as asthmatics in childhood and got natural remission for at least 3 years(with median duration of 6 years). Group II (normal controls): 21 healthy college students including 10 males and 11 females, mean age of 22.5 years, had no history of asthma or other allergic diseases. The intravenous blood was taken from all subjects with EDTA as anticoagulant for study. The airway responsiveness were measured by methacholine bronchial provocation test(PC20). The sVCAM-1 was measured with ELISA, according to the manual of the kit. Methacholine was atomized by Wright atomizer [Devilbiss AP-50, USA, driven by air compressor, with a constant atomizing volume of (0.13 +/- 0.02) ml/min, diameter of atomizes particles 1.3-3.0 microns]. Its concentration was redoubled from 0.03 to 128 g/L until a certain dose as PC20 value triggering forced expiratory volume in one second (FEV1) decreased by 20% reached. The eosinophil cationic protein (ECP) levels were measured with enzyme-linked immuno-CAP system. Blood eosinophils(> 330/mm3 as being above normal) and basophils (> 33/mm3 as abnormally increased) were counted using Acian blue dyeing. RESULTS: (1) The mean value of sVCAM-1 of group I (63.7 +/- 31.7) micrograms/L was significantly higher than that of group II (41.9 +/- 11.7) micrograms/L. (2) The percentage of the cases with increased eosinophils in group I was 15.0% (3/20), had no significant difference compared with that in group II (4.8%, 1/21). The percentage of the cases with increased basophils of group I was 45.0%(9/20), significantly higher than that of group II, 4.8%(1/21), P < 0.01. (3) The blood ECP level of group I was (2.7 +/- 1.3) micrograms/L, simillar to that of group II (2.18 +/- 0.5) micrograms/L. (4) The PC20 value of group I (M = 2.6 g/L) was significantly lower than that of group II (M = 128 g/L). (5) The basophil count negatively correlated with the PC20(r = -0.66), however, the sVCAM-1 did not have significant correlation with the basophil count or with the PC20. CONCLUSION: The quantity and activity of eosinophils in asthmatics with remission at least 3 years are droped to the normal level, but the expression of VCAM-1, quantity of basophils were still higher than normal. The airway responsiveness had negative correlation with the basophil count.

Adult↗
PubMed2001

[Separation, purification and identification of angiotensin converting enzyme inhibitory silk fibroin peptide].

Silk fibroin peptides could be obtained from soluble silk fibroin by enzymatic hydrolysis. Its hydrolyzates produced with Alcalase showed significant inhibitory activity against the angiotensin I-converting enzyme (ACE). One inhibitory peptide from the hydrolyzate at a degree of hydrolysis of 20% (sample A20) was purified and identified. Sample A20 was first isolated by size exclusion chromatography(SEC), eluted with 0.01 mol/L hydrochloric acid solution on a Sephadex G-15 column (1.6 cm i.d. x 100 cm). The peak of No. 5 on the SEC chromatography was further purified by reversed-phase HPLC (mu Bondapak C18 P/N 84176 column, 7.8 mm i.d. x 300 mm), eluted with a linear gradient elution with acetonitrile from 0% to 15% at temperature (30 +/- 2) degrees C. Then the pure peptide with ACE inhibitory activity was obtained, the amino acid sequence of which was identified as Gly-Tyr by mass spectrometry.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Nicotine effects on regional cerebral blood flow in awake, resting tobacco smokers.

The hypothesis for this research was that regional cerebral blood flow (rCBF) would increase following nasal nicotine administration to overnight abstinent tobacco smokers in relationship to the known brain distribution of nicotinic cholinergic receptors (nAChRs). Nine male and nine female healthy adult smokers were studied. They abstained overnight from tobacco products for 10 or more hours prior to study the next morning. Nicotine nasal spray was given in doses of 1-2.5 mg total with half in each nostril while the subject was awake and resting in a supine position. Oleoresin of pepper solution in a similar volume was used as an active placebo to control for the irritating effects of nicotine. Both substances were given single blind to the subjects. Positron emission tomography (PET) with H(2)(15)O was used to measure rCBF. The data from each subject volunteer were normalized to global activity to better assess regional brain changes. Both nasal nicotine and pepper spray produced similar increases in CBF in somesthetic area II, consistent with the irritant effects of both substances. The mean rCBF effects of nasal pepper were subtracted from those of nasal nicotine to determine the actions of nicotine alone. The latter produced increases in rCBF in the thalamus, pons, Brodman area 17 of the visual cortex, and cerebellum. Some brain areas that contain a large number of nAChRs, such as the thalamus, showed an increase in CBF. Other areas that have few nAChRs, such as the cerebellum, also showed an increase in relative CBF. The hippocampal/parahippocampal areas showed greater regional decreases (left) and lesser increases (right) in CBF that correlated with the increase in plasma arterial nicotine concentrations. The results obtained indicate complex primary and secondary effects of nicotine in which only some regional brain CBF changes correlate with the known distribution of nAChR. No gender differences were noted.

Administration, Intranasal↗