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Biomedical subjects

Jie Liu

Publications and source records attributed to Jie Liu.

At least 199 records · Page 11Linked to original sources
PubMed2005

Electrochemical detection of nitric oxide in biological fluids.

The challenges that must be overcome in order to detect nitric oxide (NO) in biological fluids include its low physiological concentration (1-nM) and its short half-life (a few seconds or less). Electrochemistry is capable of making such measurements, if certain principles, both biological and electrochemical, are kept in mind. We discuss these principles and demonstrate an example of practical measurement by detecting NO release in a drop of blood suspended within the reference electrode of an electrochemical cell. We elicit the NO release by decreasing the oxygen concentration in the gaseous atmosphere surrounding the drop.

Electrochemistry↗
PubMed2005

COX2-related multicentric mixed-type Castleman's disease in a young man.

BACKGROUND: A 34-year-old male presented with a 5-month history of fatigue, anorexia, low fever, night sweats, and oliguria with edema of the eyelid, exacerbated by abdominal distension and mild diarrhea of 3 weeks duration. Physical examination showed positive signs of ascites, palpable spleen, slight abdominal tenderness and mild rebound tenderness in the lower abdomen, and edema of the lower limbs. Initial laboratory tests revealed abnormal liver biochemistry and increased protein concentration in the urine. Chest X-ray showed minimal pleural effusion in both sides of the thoracic cavity, and ultrasound detected moderate ascites, several small lymph nodes in the retroperitoneum, and mild splenomegaly with widening of the splenic vein. A lymph node biopsy established the diagnosis, and cytokine analysis in the serum revealed COX2 as the possible mediator. INVESTIGATIONS: Abdominal paracentesis, chest X-ray, abdominal ultrasound, thoracic and abdominal CT scans, gastroscopy, colonoscopy, biopsies of the liver, bone marrow and lymph nodes, immunophenotype staining for lymphocytes, cytokine analysis. DIAGNOSIS: COX2-related multicentric mixed-type Castleman's disease. MANAGEMENT: Chemotherapy and COX2 inhibitors.

Adult↗
PubMed2005

Platelet-derived growth factor enhances expansion of umbilical cord blood CD34+ cells in contact with hematopoietic stroma.

Stem cell expansion remains an elusive but highly desirable goal. Here we show that platelet-derived growth factor (PDGF), along with cultured endothelial or stromal cells, significantly enhances expansion of human CD34+ cells in vitro. In media supplemented with thrombopoietin, stem cell factor, flt-3 ligand, and granulocyte-colony stimulating factor, CD34+ cells, as well as CFU-GM, BFU-CFU-E, CFU-GEMM, and CFU-MK, increased by 34.3-, 138-, 59.7-, 38.4-, and 86.0-fold, respectively. Co-culturing of CD34+ cells with cultured stromal cells or human umbilical cord vein endothelial cells (HUVECs) greatly enhanced expansion efficiency. The presence of PDGF (50 ng/ml) further augmented expansion, such that increases of 77.0-, 262-, 90.0-, 93.0-, and 200-fold, respectively, were achieved. Six weeks after infusion of expanded cells into NOD/SCID mice, human CD45+ cells were detected in recipients' bone marrow, spleen, and peripheral blood. Our results provide a rationale for development of a stem cell expansion protocol for clinical applications.

Animals↗
PubMed2005

Coded pulse excitation for ultrasonic strain imaging.

Decorrelation strain noise can be significantly reduced in low echo-signal-to-noise (eSNR) conditions using coded excitation. Large time-bandwidth-product (>30) pulses are transmitted into tissue mimicking phantoms with 2.5-mm diameter inclusions that mimic the elastic properties of breast lesions. We observed a 5-10 dB improvement in eSNR that led to a doubling of the depth of focus for strain images with no reduction of spatial resolution. In high eSNR conditions, coded excitation permits the use of higher carrier frequencies and shorter correlation windows to improve the attainable spatial resolution for strain relative to that obtained with conventional short pulses. This paper summarizes comparative studies of strain imaging in noise-limited conditions obtained by short pulses and four common aperiodic codes (chirp, Barker, suboptimal, and Golay) as a function of attenuation, eSNR and applied strain. Imaging performance is quantified using SNR for displacement (SNRd), local modulation transfer function (LMTF), and contrast-to-noise ratio for strain (CNRepsilon). We found that chirp and Golay codes are the most robust for imaging soft tissue deformation using matched filter decoding. Their superior performance is obtained by balancing the need for low-range lobes, large eSNR improvement, and short-code duration.

Animals↗
PubMed2005

Alpha-latrotoxin modulates the secretory machinery via receptor-mediated activation of protein kinase C.

The hypothesis whether alpha-latrotoxin (LTX) could directly regulate the secretory machinery was tested in pancreatic beta cells using combined techniques of membrane capacitance (Cm) measurement and Ca2+ uncaging. Employing ramp increase in [Ca2+]i to stimulate exocytosis, we found that LTX lowers the Ca2+ threshold required for exocytosis without affecting the size of the readily releasable pool (RRP). The burst component of exocytosis in response to step-like [Ca2+]i increase generated by flash photolysis of caged Ca2+ was also speeded up by LTX treatment. LTX increased the maximum rate of exocytosis compared with control responses with similar postflash [Ca2+]i and shifted the Ca2+ dependence of the exocytotic machinery toward lower Ca2+ concentrations. LTXN4C, a LTX mutant which cannot form membrane pores or penetrate through the plasma membrane but has similar affinity for the receptors as the wild-type LTX, mimicked the effect of LTX. Moreover, the effects of both LTX and LTXN4C) were independent of intracellular or extracellular Ca2+ but required extracellular Mg2+. Our data propose that LTX, by binding to the membrane receptors, sensitizes the fusion machinery to Ca2+ and, hence, may permit release at low [Ca2+]i level. This sensitization is mediated by activation of protein kinase C.

Animals↗
PubMed2005

Mycophenolate mofetil as a treatment for refractory idiopathic thrombocytopenic purpura.

AIM: To determine whether mycophenolate mofetil (MMF) has beneficial effects on refractory idiopathic thrombocytopenic purpura (ITP) and the corresponding cellular mechanism. METHODS: Twenty refractory ITP patients resistant to corticosteroid and/or splenectomy and chemical therapy were given MMF 1.5-2.0 g/d orally for a 2 to 4-month period. Serum immunoglobulin was detected by rate nephelometry. Platelet-associated antibodies (PAIgG) were assayed by enzyme-linked immunosorbant assay. The immunophenotypic analysis was performed on a flow cytometer and cell apoptosis was detected with transferase mediated dUTP biotin nick end labeling (TUNEL) method. RESULTS: Sixteen of the 20 (80%) patients had responses to MMF treatment; 9 (45%) achieved a complete response, 4 (20%) achieved a partial response, and 3 (15%) achieved a minor response. The therapeutic effects were found to be better in male patients than female patients. The number of CD3+ peripheral blood cells (PBCs) and CD4+ PBCs increased and the number of CD8+ PBCs decreased. The plasma level of IgG, IgM, IgA and platelet associated IgG (PAIgG) decreased in 86% of the patients. TUNEL assay showed that mycophenolate acid (MPA) 0.1 mmol/L induced apoptosis of peripheral blood mononuclear cells isolated from refractory ITP patients. The apoptosis rate was increased in male patients after treatment with MPA, but was unchanged in female patients. CONCLUSION: Therapy for a period of 8 to 16 weeks with median-dose of MMF was valuable for the treatment of refractory ITP.

Adolescent↗
PubMed2005

Spontaneous ring-like self-assembly of BaF2 nanoparticles.

Self-assembly of BaF2 nanoparticles was described. BaF2 nanoparticles were prepared by microemulsion technology. The self-assembly of the particles is spontaneous without coating reagent on the surface or external force being applied during the procedure of sample preparation. XRD examination and ICP data showed the phase purity of the final product; FTIR spectroscopy confirmed that there was no organic species leaved in the product. By depositing one drop of colloid solution containing BaF2 particles on the TEM grid directly, we can get the ring-like self-assembly with larger particles dispersing peripherally to form a ring and smaller particles inside this ring forming circles.

Barium Compounds↗
PubMed2005

Endocannabinoid activation at hepatic CB1 receptors stimulates fatty acid synthesis and contributes to diet-induced obesity.

Endogenous cannabinoids acting at CB(1) receptors stimulate appetite, and CB(1) antagonists show promise in the treatment of obesity. CB(1) (-/-) mice are resistant to diet-induced obesity even though their caloric intake is similar to that of wild-type mice, suggesting that endocannabinoids also regulate fat metabolism. Here, we investigated the possible role of endocannabinoids in the regulation of hepatic lipogenesis. Activation of CB(1) in mice increases the hepatic gene expression of the lipogenic transcription factor SREBP-1c and its targets acetyl-CoA carboxylase-1 and fatty acid synthase (FAS). Treatment with a CB(1) agonist also increases de novo fatty acid synthesis in the liver or in isolated hepatocytes, which express CB(1). High-fat diet increases hepatic levels of the endocannabinoid anandamide (arachidonoyl ethanolamide), CB(1) density, and basal rates of fatty acid synthesis, and the latter is reduced by CB(1) blockade. In the hypothalamus, where FAS inhibitors elicit anorexia, SREBP-1c and FAS expression are similarly affected by CB(1) ligands. We conclude that anandamide acting at hepatic CB(1) contributes to diet-induced obesity and that the FAS pathway may be a common molecular target for central appetitive and peripheral metabolic regulation.

Animals↗
PubMed2005

Oleanolic acid nanosuspensions: preparation, in-vitro characterization and enhanced hepatoprotective effect.

Oleanolic acid is a naturally derived triterpene used clinically in the treatment of hepatitis in China, but its poor solubility often leads to poor bioavailability. In the present study, oleanolic acid nanosuspensions were prepared by the nanoprecipitation method and then systematically characterized. The average particle size of the obtained nanosuspensions was 284.9 nm, with a polydispersity index of 0.216. Transmission electron microscopy and atomic force microscopy showed that the drug existed as spherical or near-spherical nanoparticles in the nanosuspensions. Differential scanning calorimetry and X-ray diffraction studies indicated that oleanolic acid was present in an amorphous state in the lyophilized nanosuspensions. At 25 degrees C, the saturation solubility of oleanolic acid was increased by about 6 times after nanoation (25.72 microg mL(-1) vs 4.37 microg mL(-1)). In the in-vitro drug release experiments, the lyophilized nanosuspensions showed a faster drug dissolution rate than that of the coarse drug powder (approx. 90% vs 15% during the first 20 min), and nearly 95% of the oleanolic acid was released by 120 min. As evidenced by the lower serum alanine aminotransferase activity and liver malondialdehyde content, pre-treatment with oleanolic acid nanosuspensions significantly enhanced the hepatoprotective effect of oleanolic acid against carbon tetrachloride-induced liver injury.

Administration, Oral↗
PubMed2005

[Insulin resistance and effects of intravenous acute saline load on renal production of prostaglandin I2 and thromboxane A2 in salt-sensitive hypertensive patients].

OBJECTIVE: To investigate insulin resistance and the effects of intravenous acute saline load on renal production of prostaglandin I(2) (PGI(2)) and thromboxane A(2) (TXA(2)) in salt-sensitive hypertensive patients. METHODS: The 24-hour excretion of urinary 6-keto-prostaglandin F (PGF) 1alpha and thromboxane B(2) were measured before and after intravenous acute saline load in 53 hypertensive patients whose salt sensitivity had been determined. Oral glucose tolerance test and insulin release test were performed in all the subjects. RESULTS: after intravenous acute saline load, the 24-hour excretions of urinary 6-keto PGF 1alpha were significantly lower in salt-sensitive (SS) hypertensive patients than that in non-salt-sensitive (NSS) ones (316+/-57 pg/min vs 371+/-68 pg/min, P<0.01), and the decrease from baseline was much greater in SS group than that in NSS group (197+/-99 pg/min vs 136+/-101 pg/min, P<0.01). Both 24 hour urinary excretion of TXA(2) and the increase in urinary excretion of TXA(2) were significantly greater in SS hypertensive patients than those in NSS ones after salt loading (394+/-32 pg/min vs 359+/-44 pg/min, P<0.01, and 80+/-47 pg/min vs 47+/-45 pg/min, P<0.01, respectively). The plasma glucose and insulin concentrations in every time point were much higher in SS hypertensive subjects than that in NSS ones, and the former group had lower insulin sensitivity index than the latter (0.013+/-0.003 vs 0.018+/-0.004, P<0.01) CONCLUSION: Saline load produces significantly different effects on renal production of PGI(2) and TXA(2) in SS and NSS hypertensive patients, and these changes may be related to the pathophysiology of SS hypertensive patients after acute salt loading. Insulin resistance is greater in SS hypertensive patients than in NSS ones.

6-Ketoprostaglandin F1 alpha↗
PubMed2005

[Study of immunoregulation of dendritic cells in allergic rhinitis].

OBJECTIVE: To investigate the immunoregulation of dendritic cells in allergic rhinitis. METHOD: Adopting the cell culture and the enzyme linked immunosorbant assay to examine the patients' Th1/Th2 in the blood. Observing that how is the DC's function in immunoregulation of allergic rhinitis. RESULT: The concentration of the IFN-gamma advanced obviously in post-stimulatory supernatant liquid after using the mature DC. CONCLUSION: The mature dendritic cells can polarize naive T-cells into Th1 effector cells, and are recognized as having a central role in the establishment of T-cell memory and peripheral immune tolerance. DC could be exploited as targets for therapy in asthma and allergic rhinitis.

Adolescent↗
PubMed2005

[Studying on the relationship between the fluorescence occurring time and fluorescence summit wavelength].

The authors have detected the fluorescence characteristic of aromatic pollution material-anthracene by OMA and obtained its 3-D(time-wavelength-fluorescence intensity) fluorescence diagrams, three summit wavelengths's fluorescence time spectra, equal high spectra. By analyzing these spectra properties, the authors find that there is a clear order with the occurring time among the three fluorescence summit wavelengths (399 nm, 423 nm, 445 nm). Long fluorescence wave occurs earlier than short fluorescence wave. This solution is also analyzed and explained by atomic energy levels theory.

Algorithms↗
PubMed2005

[Study on identification of aconiti by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry].

OBJECTIVE: The merhod of determination of traditional Chinese medicine of aconitum root has been established by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. METHODS: With optimized matrix of 2,5-Dihydroxy- benzoic acid for herbal extract, the identification of aconitum root by MALDI-TOF-MS has been conditioned. By comparison of mass spetra of various of aconitium root, their fingerprint mass-to-charge ratios were found to perform identification. With the characteristic mass-to-charge ratios, It was shown that the mass spectrum of raw aconitum roots were obviously different from that of processed aconitum roots. RESULTS: The raw radix aconiti could be differentiated from radix aconiti preparate by determination of MALDI-TOF-MS. CONCLUSION: The identifical method of aconitum root by MALDI-TOF-MS is rapid, precise and sensitive, it can be used in toxicological analysis of medical tangle and illegal medical practice.

Aconitine↗
PubMed2005

[Mechanism of insulin-like growth factor-I affecting adhesion of trophoblast cells in vitro].

OBJECTIVE: To investigate the mechanism of insulin-like growth factor-I (IGF-I) affecting adhesion of trophoblast cells in vitro. METHODS: Trophoblast cells were obtained from early gestation at artificial abortion to set up the in vitro trophoblast cell adhesion model. The trophoblast cells were incubated with or without 10 nmol/L IGF-I and were divided into three groups (10 nmol/L IGF-I, 10 nmol/L IGF-I + alpha v beta3Ab, and control). The amount of adhered cells was assessed by examining absorbency using enzyme-linked immunoassay. Morphological changes were studied using scanning electron microscopy. The expression of phosphorylated focal adhesion kinase was determined by immunocytochemistry. RESULTS: After serum-starved trophoblast cells were incubated only with IGF-I, the mean absorbency was 0.491 +/- 0.049, obviously higher than control 0.198 +/- 0.022 and the difference was dramatic (P < 0.01). When cells were pre-treated with antibody against alpha v beta3 integrin and then incubated with IGF-I, the mean absorbency was only 0.184 +/- 0.031, distinctly lower than that incubated with IGF-I, and the difference was significant (P < 0.01), however, compared with control, there was no significant difference (P > 0.05). Scanning electron microscopy highlighted a dramatic increase in lamellipodial formation and extension in the IGF-I treated cells compared with control. Immunocytochemistry staining showed phosphorylated focal adhesion kinase was expressed in the trophoblast cells treated with IGF-I. CONCLUSIONS: 10 nmol/L IGF-I can significantly stimulate trophoblast cells adhesion to fibronectin, but antibody against alpha v beta3 integrin obviously blocks its adhesion. IGF-I can stimulate lamellipodial formation and extension at the adhesion sites, and promote adhesion of trophoblast cells to fibronectin by activating phosphorylated focal adhesion kinase.

Adult↗
PubMed2005

[Preparation of anti-morphine monoclonal antibodies with complete cross reactivity with heroin].

OBJECTIVE: To prepare and characterize anti-morphine monoclonal antibodies (mAbs) with complete cross reactivity with heroin. METHODS: Morphine-6-succinyl was conjugated with Blue carrier (BC) in the presence of carbodi imide. BALB/c mice were immunized with the holoantigens (M-6-S-BC) and Freund adjuvant, and hybridoma was generated with mouse spleen cells and Sp2/0 myeloma cells. After 3 fusions and cloning, 4 hybridoma cell lines secreting monoclonal antibodies to morphine were obtained and the mABs purified from the mouse ascites followed by characterization with enzyme-linked immunosorbent assay (ELISA). RESULTS: Four hybridoma cell lines secreting anti-morphine mAbs were established and designated as G1, G3, H4 and B1, respectively. All the mAbs belonged to IgG1 isotype and could bind to heroin better than to morphine and codeine, which were identified by competitive inhibition ELISA. CONCLUSION: The anti-morphine mAbs can bind with the opioids, especially heroin, and can be useful for sensitive detection of opioids.

Animals↗