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F Li

Publications and source records attributed to F Li.

At least 55 records · Page 3Linked to original sources
PubMed2004

Observation of a threshold enhancement in the plambda invariant-mass spectrum.

An enhancement near the m(p)+M(Lambda) mass threshold is observed in the combined pLambda and pLambda invariant-mass spectrum from J/psi-->pK(-)Lambda;+c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi(')-->pK(-)Lambda;+c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi(') decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

Journal Article↗
PubMed2004

Ventral brainstem enterogenous cyst: an unusual location.

Enterogenous cysts mostly locate in the spinal canal and have only rarely been reported in an intracranial site. We report a case of enterogenous cyst in the ventral to brainstem. The 45-year-old woman presented with paroxysmal headache and diplopia. A CT scan and MRI revealed a cystic clival mass from midbrain to medulla. Subtotal resection was performed using a sub-temporal approach and the patient made a good recovery. Pathological examination revealed that the lesion was a typical enterogenous cyst.

Brain Diseases↗
PubMed2004

Observation of the decay psi(2S)-->K0SK0L.

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Journal Article↗
PubMed2004

Evaluation of orally active poly(ADP-ribose) polymerase inhibitor in streptozotocin-diabetic rat model of early peripheral neuropathy.

AIMS/HYPOTHESIS: Poly(ADP-ribose) polymerase activation depletes NAD+ and high-energy phosphates, activates protein kinase C, and affects gene expression in various tissues. This study was designed to characterise the effects of the potent, orally active poly(ADP-ribose) polymerase inhibitor PJ34 in the Wistar rat model of early diabetic neuropathy. METHODS: Control and streptozotocin-diabetic rats were maintained with or without PJ34 treatment (30 mg x kg(-1) x day(-1)) for two weeks, after two weeks without treatment. Endoneurial blood flow was assessed by hydrogen clearance; metabolites and high-energy phosphates were assayed by enzymatic spectrofluorometric methods; and poly(ADP-ribose) was detected by immunohistochemistry. RESULTS: Blood glucose concentrations were increased to a similar extent in untreated and PJ34-treated diabetic rats compared with controls. Intense poly(ADP-ribose) immunostaining was observed in the sciatic nerve of diabetic rats, but not in other groups. Final sciatic motor nerve conduction velocity and digital sensory nerve conduction velocity were reduced by 24% and 22% respectively in diabetic rats compared with controls (p<0.01 for both), and both were 98% corrected by PJ34 (p<0.01 vs diabetic group for both). In contrast, with PJ34 treatment, nerve blood flow showed a modest (17%) increase, and vascular conductance showed a tendency to increase. Free mitochondrial and cytosolic NAD+:NADH ratios, assessed from the glutamate and lactate dehydrogenase systems, phosphocreatine concentrations, and phosphocreatine:creatine ratios were decreased in diabetic rats and essentially normalised by PJ34. In both untreated and PJ34-treated diabetic rats, nerve glucose, sorbitol and fructose were increased to a similar extent. PJ34 did not affect any variables in control rats. CONCLUSIONS/INTERPRETATION: Short-term poly(ADP-ribose) polymerase inhibitor treatment reverses functional and metabolic abnormalities of early diabetic neuropathy. Complete normalisation of nerve blood flow is not required for correction of motor or sensory nerve conduction velocities, provided that a therapeutic agent can restore nerve energy state via direct action on Schwann cells.

Animals↗
PubMed2004

Tumor-specific gene expression using the survivin promoter is further increased by hypoxia.

Increasing evidence indicates that survivin, an inhibitor of apoptosis protein (IAP), is expressed in human cancer cells but is absent from most normal adult tissues. Here, we examined the feasibility of using a survivin promoter (Sur-P) to direct therapeutic expression of a proapoptotic gene specifically in human tumor cells. First, we demonstrated that this promoter was highly active in human tumor cells but not in normal cells. Second, we found that Sur-P activity was upregulated by hypoxia in tumor cells. Third, to further enhance this promoter's activity under hypoxia, we added a hypoxia-responsive element (HRE) from the vascular endothelial growth factor gene promoter in its 5' region, and showed that this combination resulted in a further increase in the level of gene expression in hypoxic tumor cells. Finally, we demonstrated that expression of an autocatalytic reverse caspase-3 gene by this promoter specifically induced apoptotic cell death in human tumor cells but not in normal cells. These findings support the use of promoters Sur-P or chimeric HRE-Sur-P for generating novel vectors for cancer gene therapy.

Apoptosis↗
PubMed2004

CISOC-PSCT: a predictive system for carcinogenic toxicity.

A SAR based carcinogenic toxicity prediction system, CISOC-PSCT, was developed. It consisted of two principal phases: the construction of relationships between structural descriptors and carcinogenic toxicity indices, and prediction of the toxicity from the SAR model. The training set included 2738 carcinogenic and 4130 non-carcinogenic compounds. Three predefined topological types of substructures termed Star, Path and Ring were used to generate the descriptors for each structure in the training set. In this system, the defined carcinogenic toxicity index (CTI) was obtained from the probability of a structural descriptor to either belong to the carcinogenic or non-carcinogenic compounds. Based on these structural descriptors and their CTI, a SAR model was derived. Then the carcinogenic possibility (CP) and the carcinogenic impossibility (CIP) of compounds were predicted. The model was tested from a testing set of 304 carcinogenic compounds (MDL toxicity database), 460 non-carcinogenic compounds (CMC database) and 94 compounds extracted from two traditional Chinese medicine herbs.

Carcinogens↗
PubMed2004

Coumarins from Cnidium monnieri (L.) and their proliferation stimulating activity on osteoblast-like UMR106 cells.

The proliferation of various fractions of alcoholic extracts from fruits of Cnidium monnieri (L.) Cuss (umbelifera) were screened using the osteoblast-like UMR106 cells in vitro. The chloroform fraction from the crude extract was found to have the most stimulating activity. Three coumarins (osthole, bergapten and imperatorin) were isolated from this fraction by activity-guided assay, and their effects on osteoblastic proliferation were investigated. Osthole, a major pharmacologically active constituent, significantly promoted the cells' activity. Bergapten and imperatorin were less effective than osthole. These results suggested Cnidium monnieri (L.) Cuss extracts might have potential activity against osteoporosis, and its chloroform fraction might contain active constituents stimulating osteoblasts.

Cell Division↗
PubMed2003

PA-457: a potent HIV inhibitor that disrupts core condensation by targeting a late step in Gag processing.

New HIV therapies are urgently needed to address the growing problem of drug resistance. In this article, we characterize the anti-HIV drug candidate 3-O-(3',3'-dimethylsuccinyl) betulinic acid (PA-457). We show that PA-457 potently inhibits replication of both WT and drug-resistant HIV-1 isolates and demonstrate that the compound acts by disrupting a late step in Gag processing involving conversion of the capsid precursor (p25) to mature capsid protein (p24). We find that virions from PA-457-treated cultures are noninfectious and exhibit an aberrant particle morphology characterized by a spherical, acentric core and a crescent-shaped, electron-dense shell lying just inside the viral membrane. To identify the determinants of compound activity we selected for PA-457-resistant virus in vitro. Consistent with the effect on Gag processing, we found that mutations conferring resistance to PA-457 map to the p25 to p24 cleavage site. PA-457 represents a unique class of anti-HIV compounds termed maturation inhibitors that exploit a previously unidentified viral target, providing additional opportunities for HIV drug discovery.

Anti-HIV Agents↗
PubMed2003

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays.

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Journal Article↗
PubMed2003

Anti-oxidant effects of estrogen reduce [Ca2+]i during metabolic inhibition.

We previously reported that 17beta-estradiol (betaE2) inhibits the rise in [Ca(2+)](i) and [Na(+)](i) during metabolic inhibition (MI) in mouse cardiomyocytes, but the mechanism has not yet been clarified. Estrogen has been reported to have anti-oxidant properties. We, therefore, have investigated whether interaction with the estrogen receptor (ER) is involved, or whether estrogen reduces free-radical-induced impairment of Na(+)-K(+) ATPase in cardiac myocytes, and whether this effect reduces [Ca(2+)](i) rise. Male mouse ventricular myocytes were studied. Flow cytometry was used with fluo-3 for [Ca(2+)](i) measurement. Dead cells were excluded from analysis by propidium iodide fluorescence. betaE2 reduced the increase in [Ca(2+)](i) during MI even in the presence of the ER blocker tamoxifen. A similar effect on [Ca(2+)](i) was produced by its non-estrogenic isomer, betaE2-estradiol. Other hormones (estrone and estriol) with a phenolic structure also inhibited Ca(2+) overload during MI, but testosterone without the structure did not. The betaE2 effect was attenuated by inhibition of Na(+)-Ca(2+) exchanger (KB-R7943) or Na(+)-K(+) ATPase (low K(+) or ouabain), but not by block of L-type Ca(2+) channel (nifedipine). Tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid), a superoxide scavenger, decreased the rise in [Ca(2+)](i) and abolished the betaE2 effect during MI. We conclude that the acute cardioprotective effect of estrogen during MI may be mediated by an ER-independent anti-oxidant action, which results in improved function of Na(+)-K(+) ATPase.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed2003

Upregulation of survivin by HIV-1 Vpr.

The human survivin gene belongs to the family of inhibitor of apoptosis proteins (IAP) and is involved in apoptosis inhibition and regulation of cell division. The survivin gene is the only member of the IAP family whose expression is known to be regulated through the cell cycle. Survivin expression reaches the highest levels during the G(2)/M transition and then is rapidly degraded during the G(1) phase. Here we report that the human immunodeficiency virus type 1 (HIV-1) upregulates Survivin expression via survivin promoter transactivation. Vpr, an HIV-1 accessory protein that induces cell cycle arrest in G(2)/M, is necessary and sufficient for this effect. Blocking Vpr-induced G(2)/M arrest leads to elimination of the survivin promoter transactivation by Vpr. Our results suggest that Survivin may be actively involved in regulating cell viability during HIV-1 infection.

Blotting, Western↗
PubMed2003

Intranasal immunization of humans with Streptococcus mutans antigens.

To evaluate the effectiveness of a low dose of soluble or liposomal (L) glucosyltransferase-enriched preparation (E-GTF) in inducing mucosal immune responses after intranasal immunization, 12 adults were immunized on days 0 and 7 by the IN route with 62.5 microg of soluble E-GTF or L-E-GTF. An increase in the mean salivary IgA anti-E-GTF response (P < 0.03) was seen in the L-E-GTF but not the soluble E-GTF group. A significant increase (P < 0.05) in the mean specific IgA antibody activity was also seen in nasal wash from both groups. Although the nasal wash responses were higher in the L-E-GTF than in the soluble E-GTF group, they were not significantly different. The soluble E-GTF immunized group showed a higher serum IgG response than the L-E-GTF immunized group on day 90 (P < 0.05). These results indicate that as little as 62.5 microg of E-GTF, when given by the intranasal route, induced an IgA response in secretions.

Administration, Intranasal↗
PubMed2003

Effect of age on immunoglobulin A subclass distribution in human parotid saliva.

Two subclasses of immunoglobulin A (IgA) antibodies are produced in humans, IgA1 and IgA2, IgA2 being more resistant to digestion by bacterial proteases than IgA1. The amount of IgA in saliva has been shown to vary with age; however, little is known about the correlation between IgA subclass distribution in saliva and age. The purpose of this study was to determine whether differences exist in the levels and ratio of IgA subclasses in parotid saliva of children and adults. Parotid saliva was obtained from healthy children (age range 6-12 years, n = 14) and adults (age range 22-51 years, n = 20) using Schaefer cups. Samples were analyzed for levels of total IgA, IgA1, and IgA2 by ELISA. IgA and IgA1 levels were significantly higher in adults than in children. However, no differences were seen in the ratio of IgA1 and IgA2 in the two groups of subjects. These findings indicate that levels of IgA increase with age, whereas the IgA subclass ratio is established early in life.

Adult↗
PubMed2003

Sulfatides inhibit platelet adhesion to von Willebrand factor in flowing blood.

Sulfatides are sulfated glycosphingolipids present on cell surfaces that bind to adhesive proteins such as von Willebrand factor (VWF), P-selectin, laminin and thrombospondin. Previous studies have localized the sulfatide-binding site of VWF to amino acid residues Gln626-Val646 in the A1 domain. The A1 domain also contains the binding site for platelet glycoprotein Ib (GP Ib), a site that has been reported to be distinct from the sulfatide-binding site. In this study, we analyzed the interaction of sulfatides with VWF and its effect on GP Ib-mediated platelet adhesion under flow conditions. Recombinant VWF A1 domain (rVWF-A1) bound specifically and saturably to sulfatides (half-maximal concentration of approximately 12.5 microg mL(-1)), binding that was blocked by dextran sulfate (IC(50) approximately equal to 100 microg mL(-1)) but not by heparin at concentrations up to 100 U mL(-1). Furthermore, sulfatides (125 microg mL(-1)) prevented the adhesion of platelets or glycocalicin-coupled polystyrene beads to a rVWF-A1-coated surface under high shear stress. In addition, plasma VWF prebound to a sulfatide-coated surface failed to support subsequent platelet adhesion. These results provide firm evidence that sulfatides bind the VWF A1 domain at a site overlapping the GP Ib-binding site.

Cloning, Molecular↗
PubMed2003

An equation characterizing multi-heavy-metal sorption onto bentonite, forest soil and spruce bark.

An empirical equation was developed to quantitatively describe heavy metal sorption in ternary systems of lead (Pb), copper (Cu) and cadmium (Cd). The three sorbants investigated were bentonite, forest soil and spruce bark. This multi-sorption equation is based on three assumptions: the relationship between sorption and initial heavy metal concentration fits a power curve; the presence of one heavy metal proportionately reduces the sorption curve of another heavy metal; and the competition between two heavy metals is independent of the presence of other heavy metals. The multi-sorption equation modeled sorption in ternary systems to a regression fit greater than 0.96. The data required for the equation were generated from a technically straightforward and quick laboratory program involving batch adsorption tests.

Adsorption↗
PubMed2003

Protection against ischemic brain damage by GDNF affecting cell survival and death signals.

Neuroprotective effects of glial cell line-derived neurotrophic factor (GDNF) on cell survival and death signals were investigated after 90 min of transient middle cerebral artery occlusion (MCAO) in rats. Immunoreactivities of phosphorylated Akt (p-Akt), cleaved caspase-9 (c-cas9), and -3 (c-cas3) increased after the reperfusion in the penumbra in vehicle group with peaks at 3 h, 8 h, and 1 day, respectively. Topical application of GDNF (6.8 micrograms/9 microliters) on brain surface potentiated and prolonged p-Akt activation, but suppressed activation of the caspases, and reduced the number of terminal deoxynucleotidyl transferase-mediated dUDP-biotin in situ nick labeling (TUNEL) positive cells. These results suggest that GDNF plays a protective role against ischemic injury by controlling the balance between Akt pathway and caspase cascades.

Administration, Topical↗
PubMed2003

Targeting of post-ischemic cerebral endothelium in rat by liposomes bearing polyethylene glycol-coupled transferrin.

To achieve an efficient delivery targeting to post-ischemic cerebral vascular endothelium, PEG-liposome conjugated with transferrin (Tf) (Tf-PEG-liposome) was intravenously administered to the rats after 90 min of transient middle cerebral occlusion. The expression of Tf receptor (TfR) in the cerebral endothelium increased with a peak at 1 day after the reperfusion and returned to the control level by 6 days. The Tf-PEG fluorescence was marginally detectable in sham control brain, but remarkably increased with a peak at 2 days, showing about 70% of TfR positive vascular endothelium double-labeled with Tf-PEG. These results indicate that the Tf-PEG-liposome could be utilized as an efficient drug delivery tool to the brain after stroke.

Animals↗