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Biomedical subjects

F Li

Publications and source records attributed to F Li.

At least 73 records · Page 4Linked to original sources
PubMed2003

Functional improvement by electro-acupuncture after transient middle cerebral artery occlusion in rats.

Functional recovery by the application of electro-acupuncture (EA) on different acupoints was investigated using a transient middle cerebral artery occlusion (MCAO) model in rat. Acupoints were Baihui (D20) plus Renzhong (D26) (MCAO + D group), and Hanyan (G4), Xuanlu (G5), Xuanli (G6), plus Qubin (G7) (MCAP + G group). Animals with EA treatment showed significant functional improvements from 12 days after the reperfusion against those without EA treatment. Among EA treated groups, MCAO + G showed a more significant recovery than MCAO + D. Infarct volume revealed the significant reduction in the EA treated groups especially in MCAO + G at 30 days. Immunohistochemical study showed a remarkable induction of vascular endothelial growth factor (VEGF) in astrocytes of the peri-infarct area at 30 days, more in EA treated groups than in groups treated with MCAO alone. These results suggest that the acupoints applied in this study are effective for the functional recovery, and an enhanced expression of VEGF may play a certain role in recovery process after stroke.

Animals↗
PubMed2003

Regular salbutamol use increases CXCL8 responses in asthma: relationship to the eosinophil response.

Regular salbutamol use can exacerbate allergen-induced airway eosinophilia in asthmatics, but its effect on airway eosinophil chemokine responses is unknown. Asthmatic subjects (n=14) were treated for 10 days with placebo or salbutamol in a double-blind, cross-over study, then given same-dose allergen challenges. Their sputa were then analysed 1 and 7 h later for a panel of eosinophil-related cytokines. Eosinophils from five test and three control subjects were tested for expression of CXCL8/interleukin (IL)-8, and its receptors and responsiveness to CCL11/eotaxin and CXCL8/IL-8. Sputum CXCL8/IL-8, but not IL-5, CCL5/regulated on activation, T-cell expressed and secreted, CCL7/monocyte chemotactic protein-3, CCL11/eotaxin, granulocyte-macrophage colony-stimulating factor or tumour necrosis factor levels, were increased (42%) by the salbutamol treatments. The CXCL8/IL-8 levels correlated with the proportions of sputum eosinophils and these cells, but not other sputum cells, stained strongly for CXCL8/IL-8. The circulating eosinophils of the tested subjects (n=5) expressed CXCL8/IL-8 receptors and secreted high levels of this chemokine. Neutralisation of sputum CXCL8/IL-8 reduced eosinophil chemotactic responses to these samples by 19 +/- 5%. These data suggest that regular use of salbutamol can augment airway CXCL8/interleukin-8 responses to allergen challenge and that this CXCL8/interleukin-8 could contribute to the airway inflammatory response.

Adult↗
PubMed2003

Osteoblastic differentiation bioassay and its application to investigating the activity of fractions and compounds from Psoralea corylifolia L.

A cell differentiation bioassay measuring alkaline phosphatase activity was developed using osteoblast-like UMR 106 cell line as a model. The effect of fractions and compounds of Psoralea corylifolia L. extract on osteoblastic differentiation was investigated. The fractions or compounds were co-cultured with cells for 48 h, the cellular ALP activity was then measured. The crude ethanol extract of Psoralea corylifolia L. increased ALP activity by 39.5% at a concentration of 0.1 mg/ml, and the activity was concentrated in the ethyl acetate fraction, which produced a maximum ALP activity increase of 38.2%. A significant activity was observed for a flavonoid, corylin, providing 30.0% increment in ALP. These effects suggest that Psoralea corylifolia L. extract, its ethyl acetate fraction and corylin would stimulate bone formation.

Acetates↗
PubMed2002

Activation of cell-survival signal Akt by GDNF in normal rat brain.

Glial cell line-derived neurotrophic factor (GDNF) activates protein kinase Akt/PKB by phosphorylation (p-Akt) which plays key roles in cell survival. In the current study, we investigated a temporal expression of p-Akt by immunohistochemical analysis after a topical application of GDNF to normal cerebral hemisphere of rats. Although p-Akt immunoreactivity was weakly present in the sham control neural cells, GDNF application greatly enhanced it at 3 h, which lasted until 1 day. These results indicate that p-Akt is expressed in neuronal cells under physiological conditions, and that topical application of GDNF greatly enhanced the phosphorylation of Akt in normal rat brain.

Animals↗
PubMed2002

Enhanced phosphorylation of PTEN in rat brain after transient middle cerebral artery occlusion.

A phosphatase PTEN (phosphatase and tensin homologue deleted on chromosome 10) is a tumor suppressor gene that suppresses cell growth, inhibits cell migration, and induces apoptosis. Phosphorylated form of PTEN (p-PTEN) is a key survival factor relating PI3K-Akt pathway and their downstream effectors. A spatiotemporal profiles of PTEN and p-PTEN expression were immunohistochemically examined after 90 min of transient middle cerebral artery occlusion in rats. In the ischemic core, PTEN progressively decreased by 3 days, whereas a rapid but transient increase of p-PTEN was found with a peak at 1 h after the reperfusion. In contrast, in the ischemic penumbra, PTEN showed a minor change and a gradual but sustained p-PTEN expression was observed in the ischemic penumbra with a peak at 12 h. In addition, the balance of population among strongly, moderately, and weakly stained cells was different between the ischemic core and penumbra at their peak time points. These results suggest an important role of p-PTEN for cell survival after ischemia as an upstream regulator for PI3K-Akt.

Animals↗
PubMed2002

Determination of acetone, 2-butanone, diethyl ketone and BTX using HSCC-UV-IMS.

A combination of a custom-designed ion mobility spectrometer (IMS) with a UV ionization source and a high speed capillary column (HSCC) has been developed as an analytical device for the sensitive detection of volatile organic compounds (VOCs), e.g. 2-propanone (acetone), 2-butanone and 3-pentanone (diethyl ketone) in the gas phase. A fast separation of the three selected substances and benzene, toluene and m-xylene (BTX) - all of which occur in human breath - has been achieved within less than four minutes at a carrier gas flow rate of 4.5 mL x min(-1). Multi-dimensional correlations presented support the interpretation of the acquired spectra of mixtures. Method detection limits were 2.7 microg x L(-1) for acetone and 2-butanone and 3.0 microg x L(-1) for diethyl ketone in nitrogen, respectively. The assay linear dynamic range is 4-320 microg x L(-1).

Journal Article↗
PubMed2002

Heat stress prevents mitochondrial injury in ATP-depleted renal epithelial cells.

The events that precipitate cell death and the stress proteins responsible for cytoprotection during ATP depletion remain elusive. We hypothesize that exposure to metabolic inhibitors damages mitochondria, allowing proapoptotic proteins to leak into the cytosol, and suggest that heat stress-induced hsp72 accumulation prevents mitochondrial membrane injury. To test these hypotheses, renal epithelial cells were transiently ATP depleted with sodium cyanide and 2-deoxy-D-glucose in the absence of medium dextrose. Recovery from ATP depletion was associated with the release into the cytosol of cytochrome c and apoptosis-inducing factor (AIF), proapoptotic proteins that localize to the intermitochondrial membrane space. Concomitant with mitochondrial cytochrome c leak, a seven- to eightfold increase in caspase 3 activity was observed. In controls, state III mitochondrial respiration was reduced by 30% after transient exposure to metabolic inhibitors. Prior heat stress preserved mitochondrial ATP production and significantly reduced both cytochrome c release and caspase 3 activation. Despite less cytochrome c release, prior heat stress increased binding between cytochrome c and hsp72. The present study demonstrates that mitochondrial injury accompanies exposure to metabolic inhibitors. By reducing outer mitochondrial membrane injury and by complexing with cytochrome c, hsp72 could inhibit caspase activation and subsequent apoptosis.

Adenosine Triphosphate↗
PubMed2002

Humans immunized with Streptococcus mutans antigens by mucosal routes.

Strategies aimed at the prevention of Streptococcus mutans infection and dental caries include mucosal immunization, which results in salivary anti-S. mutans responses. The purpose of this study was to evaluate the effectiveness of nasal vs. tonsillar immunization with S. mutans antigens in inducing salivary immune responses. Twenty-one adult subjects were immunized twice, within a seven-day interval, with a glucosyltransferase-enriched preparation (E-GTF) administered by nasal or tonsillar topical spray. Parotid saliva, nasal wash, and serum were collected prior to and at one- to two-week intervals for 3 months following immunization and were assayed by ELISA for anti-E-GTF activity. Results were analyzed by means of the mixed-models procedure with p < 0.05 level of significance. Significantly higher anti-E-GTF responses were detected in saliva and nasal wash samples from the group immunized by the nasal compared with the tonsillar route, indicating that nasal immunization was more effective in inducing mucosal responses in adults.

Administration, Intranasal↗
PubMed2002

Enhanced expression of phospho-Akt by electro-acupuncture in normal rat brain.

Electro-acupuncture (EA) is an effective curative method for various diseases in oriental medicine. To investigate a detailed molecular mechanism of EA stimulation, an induction of phospho-Akt (p-Akt) was examined in normal adult rat brain after 60 min of EA with acupoints of Baihui (D20) and Renzhong (D26). In the sham control brain, strong neuronal p-Akt expression was found in ventral posterolateral thalamic nucleus (VPL) and medial habenular nuclei (MHb), but moderate to weak in cortex, caudate, CA1 sector and dentate gyrus of hippocampus, and ventral posteromedial thalamic nucleus. EA stimulation generally enhanced and sustained p-Akt expression for at least 24 h especially in the regions listed above, except VPL and MHb where no apparent change was found. Western blot analysis of p-Akt confirmed the enhanced signal intensity after EA at 8 and 24 h. These results suggest that the EA on D20 and D26 acupoints activates the survival Akt signal pathway, which may be maintaining the neural functions such as cell survival and memory formation in normal brain.

Animals↗
PubMed2001

Temporal and spatial differences of PSA-NCAM expression between young-adult and aged rats in normal and ischemic brains.

Highly polysialylated neural cell adhesion molecule (PSA-NCAM) is transiently expressed specifically in newly generated cells, and is important for migration and neurite outgrowth. To investigate the effect of aging on the migration of neural stem cell (NSC) after brain ischemia, the spatiotemporal expressions of immunoreactive PSA-NCAM were examined at 4 h or 1, 3 or 7 days after 90 min of middle cerebral artery occlusion (MCAO) in the young-adult or aged rats. In the sham control brain, PSA-NCAM staining was slightly observed both in dorsal and ventral parts of subventricular zone (SVZ) in the aged brain, but only in the dorsal part of SVZ in the young brain. After transient MCAO, immunoreactivity for PSA-NCAM increased in the number and the intensity in SVZ ipsilateral to MCAO in the young-adult brains and became the peak at 1 day, while that was at 3 days in the aged brains. These findings suggest that PSA-NCAM was located in different spatial distribution in normal condition between young and old rats. PSA-NCAM was induced after ischemia, and the temporal expression was also different after transient MCAO between young and older rats.

Aging↗
PubMed2001

Growth factor regulation of the molecular chaperone calnexin.

Heregulin-beta1 (HRG) is a regulatory polypeptide having several distinct biological effects in mammary epithelial cells. To address the hypothesis that HRG selectively regulates gene expression, we performed differential display screening using cells grown in the presence or absence of HRG. One cDNA clone upregulated by HRG was identical to human calnexin, a protein with molecular chaperone function. This is the first demonstration of the regulation of calnexin mRNA and protein expression by a physiologically relevant polypeptide factor in human breast cancer cells. HRG stimulation also caused a rapid redistribution of calnexin from vesicle-like structures in the cell cytoplasm to the perinuclear area and to the cell membrane. Furthermore, HRG induced colocalization and physical interaction of calnexin with the HER2 growth factor receptor. Finally, calnexin protein levels were increased in progressive stages of human breast cancer. These findings suggest that stimulation of calnexin expression by HRG may constitute a mechanism of protein redistribution and facilitate downstream signaling events in growth-factor-activated cells.

Breast Neoplasms↗
PubMed2001

Shock waves in a dusty plasma.

In the present paper, shocks in a dusty plasma are studied. A set of macroscopic shock equations are introduced in which the charge on the dust particles and the electrostatic potential in the dusty plasma have been taken into account. It is found that two shock modes may exist in a dusty plasma. One that is called the fast mode corresponds to an acoustic wave and the other, called the slow mode, corresponds to a dust-acoustic wave. The results show that the electrostatic energy of dust particles affects the shock speed and shock heating. The shock speed of the slow mode is found to be strongly dependent on the nondimensional dust density parameter p. In a tenuous dust plasma of p<<1 for the slow mode, the flow of energy as the shock heats is mainly converted into thermal energy of the dust particles; for the fast mode, the plasma heating may be reduced and partly transferred into an increase of the charge on the dust particles when they cross the shock.

Journal Article↗
PubMed2001

Solid-phase microextraction of monocyclic aromatic amines using novel fibers coated with crown ether.

Three solid-phase microextraction (SPME) fibers prepared by the sol-gel method, containing hydroxydibenzo-14-crown-4 (OH-DB14C4), dihydroxy-substituted saturated urushiol crown ether (DHSU14C4) and 3,5-dibutyl-unsymmetry-dibenzo-14-crown-4-dihydroxy crown ether (DBUD14C4), respectively, were evaluated for the determination of aromatic amine (aniline, m-toluidine, N,N-diethylaniline, N-ethyl-m-toluidine, 3,4-dimethylaniline). The sol-gel-derived hydroxy-dibenzo14-crown-4-coated fiber has the best affinity for several aniline derivatives. Optimization was carried out for the determination of aromatic amines with SPME fibers. The linearity was from 0.11 to 29 microg/ml and detection limits varied from 0.17 to 0.98 ng/ml. Relative standard deviation (n=5) was found to be 3.23-6.20%. The coating proved to be very stable at high temperature (to 340 degrees C) and in different solvents (organic and inorganic). The method was applied to the determination of aromatic amines in wastewater samples from a pharmaceutical factory.

Amines↗
PubMed2001

Comparative evaluation of single-level closing-wedge vertebral osteotomies for the correction of fixed kyphotic deformity of the lumbar spine: a cadaveric study.

STUDY DESIGN: Anatomic study. OBJECTIVES: To compare spinal osteotomies with respect to obtainable correction and change in anterior height and distance of the spinal column and to describe a modification of the decancellation closing-wedge osteotomy to obtain further correction. SUMMARY OF BACKGROUND DATA: Fixed kyphotic deformity of the lumbar spine can cause difficulty with sitting, lying flat, and pain and can pose a risk to adjacent spinal cord and nerves as well as impair respiratory and abdominal function. Various corrective osteotomies have been described. Osteotomies involving decancellation and a closing wedge of the apical vertebra theoretically decrease the risk to anterior vascular structures. METHODS: Single-level vertebral osteotomies were performed on three groups of fresh-frozen human cadaveric lumbar spines. Group 1 underwent a conventional anterior opening-wedge/posterior closing-wedge osteotomy, Group 2 underwent a conventional decancellation posterior closing-wedge osteotomy, and Group 3 underwent our modified decancellation posterior closing-wedge osteotomy. Sagittal plane angulation as well as anterior height and distance of the spinal column were measured before and after osteotomy. RESULTS: The mean correction was 38 degrees for Group 1, 36 degrees for Group 2, and 49 degrees for Group 3. The mean change in anterior height and distance was 20 and 30 mm, respectively, for Group 1. For Groups 2 and 3 it was only 2-4 mm. CONCLUSIONS: The authors recommend single-level posterior decancellation procedures for correction of fixed kyphotic deformities of the thoracolumbar spine to decrease the risk to anterior neurovascular structures. An additional 10-13 degrees of correction can be obtained with the authors' modification.

Cadaver↗
PubMed2001

Gender influences [Ca(2+)](i) during metabolic inhibition in myocytes overexpressing the Na(+)-Ca(2+) exchanger.

BACKGROUND: The Na(+)-Ca(2+) exchanger (NCX) may contribute to Ca(2+) overload and injury in ischemic cardiomyocytes. Recently, NCX overexpression was reported to increase ischemia/reperfusion injury in male and oophorectomized female but not in female mice. We therefore measured the effects of gender and estrogen on [Ca(2+)](i) and [Na(+)](i) during metabolic inhibition (MI) in myocytes from wild-type (WT) and transgenic (TG) mice overexpressing NCX. METHODS AND RESULTS: Flow cytometry was used with fluo 3 for [Ca(2+)](i) and sodium green for [Na(+)](i) measurements. Male TG mouse myocytes had higher [Ca(2+)](i) after 30 minutes of MI (1086+/-160 nmol/L, n=8) than male WT (688+/-104 nmol/L, n=9, P=0.01). The increase in [Ca(2+)](i) during MI induced by NCX overexpression in female myocytes was not significant, however (TG 552+/-62 nmol/L, n=9; WT 426+/-44 nmol/L, n=7). The magnitude of rise in [Ca(2+)](i) during MI was greater in male than female myocytes. KB-R7943, an NCX inhibitor, abolished the effect of NCX overexpression but did not totally eliminate the effect of gender on [Ca(2+)](i) during MI. NCX current density and basal Na(+) pump function were not influenced by gender. The rise in [Na(+)](i) during MI was greater in male than in female myocytes. Estrogen attenuated the increase in [Ca(2+)](i) and [Na(+)](i) in male myocytes during MI and abolished the gender difference in [Na(+)](i) during MI. CONCLUSIONS: Increased expression of NCX results in a more marked rise in [Ca(2+)](i) during MI in male than in female mouse myocytes. This gender difference appears to be mediated in part by an inhibitory effect of estrogen on the rise in [Na(+)](i), an NCX modifier, during MI.

Animals↗
PubMed2001

Characterization of fortilin, a novel antiapoptotic protein.

Apoptosis is meticulously controlled in living organisms. Its dysregulation has been shown to play a key role in a number of human diseases, including neoplastic, cardiovascular, and degenerative disorders. Bcl-2 family member proteins and inhibitors of apoptosis proteins are two major negative regulators of apoptosis. We report here the characterization of novel antiapoptotic protein, fortilin, which we identified through yeast two-hybrid library screening. Sequence analysis of fortilin revealed it to be a 172-amino acid polypeptide highly conserved from mammals to plants. Fortilin is structurally unrelated to either Bcl-2 family member proteins or inhibitors of apoptosis proteins. Northern blot analysis showed the fortilin message to be ubiquitous in normal tissue but especially abundant in the liver, kidney, and small intestine. Western blot analysis using anti-fortilin antibody showed more extensive expression in cancerous cell lines (H1299, MCF-7, and A549) than in cell lines derived from normal tissue (HEK293). Immunocytochemistry using HeLa cells transiently expressing FLAG-tagged fortilin and immunohistochemistry using human breast ductal carcinoma tissue and anti-fortilin antibody both showed that fortilin is predominantly localized in the nucleus. Functionally, the transient overexpression of fortilin in HeLa cells prevented them, in a dose-dependent fashion, from undergoing etoposide-induced apoptosis. Consistently, U2OS cells stably expressing fortilin protected the cells from cell death induced by etoposide over various concentrations and durations of exposure. In addition, fortilin overexpression inhibited caspase-3-like activity as assessed by the cleavage of fluorogenic substrate benzyloxycarbonyl-DEVD-7-amido-4-(trifluoromethyl)coumarin. Furthermore, the antisense depletion of fortilin from breast cancer cell line MCF-7 was associated with massive cell death. These data suggest that fortilin represents a novel antiapoptotic protein involved in cell survival and apoptosis regulation.

Amino Acid Sequence↗
PubMed2001

Induction of pulmonary allergen-specific IgA responses or airway hyperresponsiveness in the absence of allergic lung disease following sensitization with limiting doses of ovalbumin-alum.

Respiratory allergies represent a failure to generate nonpathogenic responses to innocuous foreign materials. Herein we assessed the role of the sensitizing dose of allergen in this response/nonresponse paradigm, sensitizing BALB/c mice with 5 ng-2 microg of OVA-alum and assessing their responses to repeated OVA aerosol challenge. Mice sensitized with < or = 25 ng of OVA-alum did not develop atopic antibodies, airway hyperresponsiveness (AHR), eosinophilia, or pulmonary Th2 responses, but the 25-ng group animals did develop significant IgA responses. The mice sensitized with 100 ng of OVA-alum developed AHR in the absence of detectable allergic disease, while the mice sensitized with 250 ng-2 microg of OVA/alum developed full-spectrum allergic disease (i.e., eosinophilia, IgE, IgG1, pulmonary Th2 cytokine responses, and AHR). These data indicate that limiting doses of allergen can differentially induce IgA or AHR in the absence of atopic disease in mice.

Allergens↗