Biomedical subjects

J Luo

Publications and source records attributed to J Luo.

At least 145 records · Page 8Linked to original sources

PubMed2000

[Study on statistical method of distribution for erythrocyte morphological features by computerized image processing].

This study sought to develop a new statistic method for the semiautomatic analysis and classification of erythrocyte morphology based on the morphological features and shape analysis of erythrocytes by computer image processing. Shape factor as the description of the erythrocyte morphological features was used for the shape classification of erythrocytes. And the models and algorithms of erythrocytes image segmentation, cell body shape recognition and measure can be implemented through the VC++. The present method can efficiently and semi-automatically provide the statistical analysis of erythrocyte morphology, and can give the distribution of erythrocyte morphological features. The result showed that there was a significant difference between the distribution curves of the normal erythrocyte morphology (one apex) and hemolytic anemia's (two apices). By this way, it can be obtained the proportion data of different cell bodies' shapes. This method could provide some information for the study and diagnosis of the diseases (e.g. hemolytic anemia, pre-leukemia) related to erythrocyte morphology.

Algorithms↗

PubMed2000

[Increased radiosensitivity of lung cancer cell lines related with the functionally replaced p14ARF gene].

OBJECTIVE: To assess the possibility that whether restored or enforced function of p14ARF could influence the radiosensitivity of lung cancer cells in vitro. METHODS: Human lung cancer cell lines with various endogenous backgrounds in INK4a, p53 and Rb genes were used as the recipients of the wild-type p14ARF gene. The expression of p14ARF mRNA and protein was detected with RT-PCR, immunohistochemistry and Western immunoblot after G418 selection. Clones expressing both p14ARF mRNA and protein were identified and selected for further experiments. By comparing with the parental and negative control cells prepared with empty vector, the effects of exogenously transfected p14ARF on cell cycle distribution, cell survival fraction and radiation-induced proportion of apoptosis were analyzed. RESULTS: The cell cycles of three wild-type p53 cell lines were arrested in G1 phase or G1 and G2-M phases. A significant decline in the proportion of S phase was observed in H460-p14ARF and A549-p14ARF cells, with decreased survival fraction and prolonged G2 delay after irradiation. We also observed in A549-p14ARF cells an increased percentage of apoptosis when radiated. CONCLUSION: The exogenously transfected wild-type p14ARF could increase the radiosensitivity of some lung cancer cells. It appears that cell cycle redistribution of cells after acquiring p14ARF may be the main explanation for the enhanced sensitivity. The increased apoptosis proportion of A549-p14ARF cells in response to radiation indicates a fortified p53 function and might partly contribute to the increased sensitization.

Carcinoma, Non-Small-Cell Lung↗

PubMed2000

[Experimental study of biologic effects of tumour necrosis factor-alpha on scar-derived fibroblasts].

OBJECTIVE: To investigate the biologic effects of tumour necrosis factor-alpha(TNF-alpha) on scar-derived fibroblasts and to evaluate the role of TNF-alpha in genesis, prevention and treatment of scar. METHODS: Cell strains were established by tissue culture technique. To study the fibroblasts derived from hypertrophic scar and normal dermis, cytoactivity and expression of fibronectin (FN) were determined by MTT, FCM and immunofluorescence. RESULTS: 1. When TNF-alpha is at a high concentration (1,000 U/ml increases), the cytoactivity of hypertrophic scar fibroblasts was decreased significantly, and the positive rate of FN expression was decreased by 11.7%. 2. Cytoactivity of normal dermis fibroblasts was increased with TNF-alpha while the positive rate of FN expression was increased by 9.6%. CONCLUSIONS: TNF-alpha has different biological effects on fibroblasts derived from hypertrophic scar or normal dermis. Studying the regulative mechanisms of TNF on abnormal scar will probably provide a new way to prevent and cure it.

Adult↗

PubMed2000

[The role of beta-ray induced fibroblasts apoptosis on the inhibition of hypertrophic scar].

OBJECTIVE: To investigate the role of beta-ray induced apoptosis of the fibroblasts on the inhibition of hypertrophic scar. METHODS: A series of patients with hypertrophic scar were grouply treated with a certain dose beta-ray. A liopic sample was taken in each patients. Its was then examined with MTT[3-(4,5-dimethylthiazol.-2-yl)-2,5-dipheny1 terazolium-bromide] technique for deciding the inhibition rate of the fibroblasts, with electron microscope technique, DNA agarose gel electrophoresis and flow cytometry for evaluating the morphological and biochemical characteristics of the fibroblast. RESULTS: The beta-ray radiation resulted in significant inhibition of the fibroblast. The features of fibroblast apoptosis(e.g.: apoptotic bodies, DNA ladders band and hypodiploid DNA peak) could be seen in the group with lower does (10 Gy). The features of fibroblast necrosis could also be found in the group with higher does(20 Gy). CONCLUSIONS: The beta-ray radiation could have the effect for inhibiting the proliferation of scar-derived fibroblast, but with dose dependence. It could be used for the treatment and(or) the prevention of hypertrophic scar.

Apoptosis↗

PubMed2000

[The effects of exogenous p16 gene on proliferation and apoptosis of human nasopharyngeal carcinoma cell line CNE-2].

OBJECTIVE: To study the effects of exogenous p16 gene on proliferation and apoptosis of human nasopharyngeal carcinoma cell line CNE-2. METHODS: Exogenous p16 gene was transfected into CNE-2 cells by lipofectin. After G418 selection, we obtained p16 stably expressed NPC cell clones (CNE-2-p16), and compared it with the mock-transfected clones(CNE-2-vect). Cell cycle was determined by flow cytometry, and cell apoptosis was examined by fluorescent (Hoechst) staining and TUNEL. P16 protein and p53 protein were stained immunohistochemically with relevant antibodies. RESULTS: Exogenous p16 gene was successfully expressed by CNE-2 2 cells. The growth of CNE-2-p16 cells was inhibited significantly. In CNE-2-p16 cells, cycle arrest in G1 phase, with decrease in percentage of S phase cells. Apoptotic index of CNE-2-p16 was significantly increased. CNE-2-p16 cells were positive for p53 protein that it was negative in CNE-2 cells. CONCLUSION: Exogenous p16 inhibits proliferation and induces apoptosis of human nasopharyngeal cancer CNE-2 cell line. It may be related to the up-regulation of wild type p53 gene.

Apoptosis↗

PubMed2000

[Clinical study of three-dimensional reconstruction of computed tomography in diagnosis of condylar fractures].

OBJECTIVE: To explore a method of getting good three-dimensional (3D) reconstruction images of temporomandibular joint (TMJ) by computed tomography (CT), and evaluate diagnosis value of 3DCT in condylar fractures. METHODS: Of the 14 patients studied, 12 were male and 2 were female with age ranging from 4 to 37 years old. 4 were old fractures and the other 10 were fresh fractures. All patients' orthopanotomograms were taken first, and then were scanned with CT. The scanning conditions were 300-345 mAS and 120kV, and the scanning methods included cross-sectional (11/14), coronal-sectional (2/14) and spiral (1/14) (pitch: 1, thickness of layers: 2.5 mm) scanning. Scanning scopes: The cross-sectional and spiral scanning were from 1 cm above the Frankfort horizontal plane to the middle of the mandibular ramus or Menton; The coronal-sectional scanning was from the mastoid process to the anterior point of the mandibular ramus or Pogonion. The thickness of the scanning layers was 2.5 mm (12/14) or 5 mm (2/14). Finally, 3D reconstructed images were obtained by shaded surface display (SSD). The cross-sectional images were obtained by being removed the cervical vertebra, the styloid process, the occipital bone and part of the mastoid process with Subtract Manual Irroi before reconstruction to avoid interference with the observation of TMJ and skull basis. RESULTS: 1. The best 3D CT reconstructed images were obtained by 2.5 mm-thin-layer cross-sectional scanning by being removed parts of the adjacent structures, and the bone lines were clear and smooth without adjacent bone structures shading TMJ. The quality of images taken spirally was similar to those taken cross-sectionally. While the coronal scanning neglected some important anatomic symbols which might be valuable to diagnose condylar displacement. 2. Of the 14 patients, 7 were unilateral condylar fractures and 7 were bilateral (21 sides altogether), among which 18 sides were high fractures of condyles and 3 were fractures of condylar neck. High oblique line fractures and comminuted fractures had major condylar rotation displacement which moved forward, downward and inside, whereas, vertical fractures only had minor displacement. Inward rotation displacement occurred in medial bent fractures. 10 of 14 patients (15 sides) had been conducted operation, and the same situations as seen from 3DCT reconstructed images were found. CONCLUSION: 3DCT images can display condylar fractures accurately and directly, and are very useful for surgeons to select treating methods of condylar fractures.

Adolescent↗

PubMed2000

[Diagnostic values of MRI in combination with DSA in vascular malformations of the head and neck].

OBJECTIVE: To evaluate prospectively diagnostic values of magnetic resonance imaging (MRI) as the initial examination for vascular malformations of the head and neck, and establish a flowchart based on radiodiagnostic features. METHODS: 45 patients with vascular malformations of the head and neck were evaluated prospectively with MRI. MRI was followed by angiography in 15 patients, contrast-enhanced CT in 15 patients. MRI was performed by using spin-echo pulse sequences with Philips Gyroscan NT 1.0 Teslaunit. RESULTS: In all cases, MRI demonstrated usefully, and there was no other single imaging modality that could provide information about internal structures and flow characteristics as much as MRI. It made differentiation between high-flow and low-flow lesions obvious, however MRI was inferior to angiography in delineation of feeder vessels. CONCLUSION: MRI can be used as the initial methods for diagnosis of vascular malformations in the head and neck, and could be combined with angiography in cases with high-flow or combined-flow lesions.

Adolescent↗

PubMed2000

[Long-term results of modified Majer-Piquet's operation in the treatment of advanced glottic type laryngeal carcinoma].

OBJECTIVE: To investigate the long term results of modified Majer-Piquet's operation in the treatment of advanced glottic type of laryngeal carcinoma. METHOD: A series of 21 cases treated were analysed, of whom, 11 were T3N0M0, 6 were T3N1M0, 4 were T4N0M0. RESULT: 3 years and 5 years survival rate were 100% and 85.7% respectively. Decannulation rate were 95.2%. All the patients could speak after decannulated, and could take food through mouth without inspiration. CONCLUSION: This operation could be used in the treatment of some advanced glottic type laryngeal carcinoma effectively.

Aged↗

PubMed2000

[HPLC quantitative analysis of berberine absorpted with macroporous resin in Rhizoma Coptidis and its preparation zuo jin wan].

Absorptive ability and elution program of macroporous resin to the berberine in the Rhizoma Coptidis and its preparation Zuo Jin Wan (containing Rhizoma Coptidis and Fructus Evodiae) were explored. The extract of 70% MeOH of samples were disolved in water, then alkalized to pH 12 with ammonia solution. The berberine was absorpted by the macroporous resin, the washed off water soluble impurity with alkalescent water, and eluted with 50% MeOH containing 0.5% H2SO4. The results of quantitative analysis of the berberine by HPLC were satisfied.

Adsorption↗

PubMed2000

[Chemical constituents of grub and grub eye drops].

The chemical constituents of grub (Holotrichia diomphalia Bates.) were systematically analyzed. The results showed that grab contained amino acids, polypeptide or protein, carbohydrate, alkaloid, organic acid, steroid et al. The analysis of amino acids in the hydrolysate in grub eye drops showed the content of Glu and Gly was high, which occupied 40.33% of total amino acids in the hydrolysate. We inferred that Glu and Gly might be the active principle on catatract and nebula.

Amino Acids↗

PubMed2000

[A new method to improve performance of BAM in presence of noise].

Algorithm of bidirectional associative memory (BAM) is depicted. BAM sum up all sample pattern with different weighting factor to recall the true pattern. The ability to recall pattern correctly is determined by how the sample pattern are weighted. Selecting the maximum of weighting factors by competition can get best performance of BAM in presence of noise.

Algorithms↗

PubMed2000

[Comparison of FTIR microspectroscopy and diffuse reflectance spectroscopy for monitor of solid phase reaction].

17 FTIR micro transmission spectra of single resin beads of each sample, from polystyrene sulfonyl chloride resin changing to polystyrene sulfonyl amide resin in solid-phase reaction in water at 0 degree C, 20 degrees C, 40 degrees C, 60 degrees C, were recorded. The reaction was monitored by the means of FTIR microspectroscopy and diffuse reflectance spectroscopy upon the products. It was showed that the pressed single bead as a piece of biscuit was able to give higher quality spectrum. In comparison, 8 diffuse reflectance spectra of each sample were also collected. It seems that the diffuse reflectance spectroscopy is a more easy dealing with and effective method to control the whole reaction. However, the microspectroscopy is the first choice to check the difference between resin beads.

Ion Exchange Resins↗

PubMed1999

Platelet-derived growth factor-mediated signal transduction underlying astrocyte proliferation: site of ethanol action.

Platelet-derived growth factor (PDGF) is a critical regulator of cell proliferation. Because ethanol inhibits cell proliferation in vivo and in vitro, we hypothesize that ethanol-induced inhibition results from differential interference with signal transduction pathways activated by PDGF. Cultured cortical astrocytes were used to examine the effects of ethanol on PDGF-mediated signal transduction, on the expression of two PDGF monomers (A- and B-chains), and on the expression of two PDGF receptor subunits (PDGFalphar and PDGFbetar). PDGF-B chain homodimer (PDGF-BB), and to a lesser extent PDGF-A chain homodimer (PDGF-AA), stimulated the proliferation of astrocytes raised in a serum-free medium. Ethanol attenuated these actions in a concentration-dependent manner. Ethanol inhibited both PDGF-AA- and PDGF-BB-mediated phosphorylation of PDGFalphar, but it had little effect on PDGFbetar autophosphorylation. Likewise, ethanol abolished the association of PDGFalphar to Ras GTPase-activating protein (Ras-GAP), but it did not affect the binding of Ras-GAP to PDGFbetar. PDGF stimulated the activities of mitogen-activated protein kinase (MAPK) in protein kinase C (PKC) independent and dependent manners. Ethanol inhibited the PKC-independent, acute activation of MAPK; however, it stimulated the PKC-dependent, sustained activation of MAPK. The expression of neither ligand was altered by exposure to ethanol for 3 d. Moreover, such treatment specifically upregulated PDGFalphar expression in a concentration-dependent manner. It did not, however, affect the binding affinity of either receptor. Thus, the signal transduction pathways initiated by PDGF-AA and PDGF-BB were differentially affected by ethanol. This differential vulnerability resulted from the preferential effects of ethanol on PDGFalphar autophosphorylation. Hence, ethanol-induced alterations are transduced through specific receptors of mitogenic growth factors.

Animals↗

PubMed1999

Attachment of C-terminus of SDF-1 enhances the biological activity of its N-terminal peptide.

The N-terminus of stromal cell-derived factor 1 (SDF-1) is known to be a critical site for CXCR4 receptor binding and signaling. However, the functional role of other regions, in particular the C-terminal helix of SDF-1, has yet to be defined. In this study, we designed and synthesized a peptide model of SDF-1 containing its N- and C-terminal regions. The attachment of the C-terminus of SDF-1, which by itself had no activity in receptor binding and signaling, dramatically increased the effect of the N-terminal fragment in inducing chemotaxis and intracellular Ca(2+) influx in sup T1 cells compared with the peptide containing only the N-terminal sequence. The enhancement in activity was not due to the increase in receptor affinity as the N,C-terminal peptide did not show higher CXCR4 binding than the N-terminal peptide. On the other hand, the intracellular Ca(2+) influx activated by the N,C-terminal peptide, but not the N-terminal peptide, was completely abolished by the addition of heparin, suggesting that the C-terminal fragment of the peptide binds glycosaminoglycans (GAGs) and exerts an effect to modulate biological activity. These data raise the possibility that the C-terminus in native SDF-1 is one of interaction sites with GAGs and may be associated with biological function of SDF-1. Furthermore, this study demonstrates an approach for the design of novel agonists or antagonists of other chemokine receptors that possess enhanced biological activity.

Binding Sites↗

PubMed1999

Association of cystic fibrosis transmembrane conductance regulator and protein phosphatase 2C.

Cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels are rapidly deactivated by a membrane-bound phosphatase activity. The efficiency of this regulation suggests CFTR and protein phosphatases may be associated within a regulatory complex. In this paper we test that possibility using co-immunoprecipitation and cross-linking experiments. A monoclonal anti-CFTR antibody co-precipitated type 2C protein phosphatase (PP2C) from baby hamster kidney cells stably expressing CFTR but did not co-precipitate PP1, PP2A, or PP2B. Conversely, a polyclonal anti-PP2C antibody co-precipitated CFTR from baby hamster kidney membrane extracts. Exposing baby hamster kidney cell lysates to dithiobis (sulfosuccinimidyl propionate) caused the cross-linking of histidine-tagged CFTR (CFTR(His10)) and PP2C into high molecular weight complexes that were isolated by chromatography on Ni(2+)-nitrilotriacetic acid-agarose. Chemical cross-linking was specific for PP2C, because PP1, PP2A, and PP2B did not co-purify with CFTR(His10) after dithiobis (sulfosuccinimidyl propionate) exposure. These results suggest CFTR and PP2C exist in a stable complex that facilitates regulation of the channel.

Animals↗

PubMed1999

The role of positively charged residues in CXCR4 recognition probed with synthetic peptides.

A high positive charge is the common characteristic shared by the beta-sheet region of stromal cell-derived factor-1 (SDF-1) and CXCR4 antagonists such as ALX40-4C consisting of nine D-arginines. This raises the question that the positively charged residues may play a role in recognition of CXCR4. To test this hypothesis, two studies were carried out using synthetic peptides. In the first study, peptide analogs possessing amino acid sequences from both the N-terminus and the beta-sheet region of SDF-1 were used as models to study the functional role of the beta-sheet region of SDF-1. The attachment of positively charged residues to the N-terminal peptide sequence of SDF-1 was found to enhance the ability of the peptides in CXCR4 binding and inhibiting CXCR4-mediated T-tropic HIV-1 entry. In the second study, two peptides containing nine arginines and the N-terminal signal sequence of SDF-1 were used as models to study the receptor binding mechanism of CXCR4 antagonists of high positive charges such as ALX40-4C. One peptide did not show signaling activity as indicated by the lack of calcium influx while another peptide induced unusual calcium influx distinct from that induced by the SDF-1 N-terminal peptide. In addition, the signal induced by the SDF-1 N-terminal peptide was inhibited by ALX40-4C. Therefore, the first study provides experimental support for the role of the highly positive beta-sheet region of SDF-1 in CXCR4 binding. The second study suggests that the binding site of ALX40-4C in CXCR4 may partially overlap with that of the SDF-1 N-terminal peptide. Both findings should be valuable for the design of SDF-1 agonists and antagonists.

Amino Acid Sequence↗

PubMed1999

Suppression of prostate cancer invasive potential and matrix metalloproteinase activity by E-cadherin transfection.

Our previous studies have demonstrated the heterogeneous expression of E-cadherin in a Dunning rat prostate tumor model. From this model, cloned E-cadherin-negative cells exhibited enhanced invasive and metastatic potential when compared with E-cadherin-positive cells. In this report, we examined the invasion suppressor function of E-cadherin in these prostate tumor cell clones. The E-cadherin gene was stably transfected into E-cadherin-negative Dunning clones. E-cadherin transfection resulted in the up-regulation of the three major catenins (alpha-, beta-, and gamma-catenin) and enhanced Ca2+-dependent cellular cohesiveness. Morphological analyses of E-cadherin transfectants revealed a reversion from a fibroblastic, motile phenotype to a more stationary epithelial phenotype. Matrix metalloproteinase 2, an important marker associated with invasive and metastatic potential, was reduced in all six stable transfected lines. A concomitant decrease in cellular invasiveness was observed, as assessed in vitro by the ability of the transfected cells to invade biological matrices. These results lend further support to the hypothesis that in this experimental system, E-cadherin plays a central role in reducing the cellular invasiveness of prostatic adenocarcinoma, due in part to the down-regulation of matrix metalloproteinase 2 activity. Moreover, the data shed additional light on the possible mechanisms involved in E-cadherin-dependent modulation of invasion.

Adenocarcinoma↗

PubMed1999

Solution structure of the major alpha-amylase inhibitor of the crop plant amaranth.

alpha-Amylase inhibitor (AAI), a 32-residue miniprotein from the Mexican crop plant amaranth (Amaranthus hypochondriacus), is the smallest known alpha-amylase inhibitor and is specific for insect alpha-amylases (Chagolla-Lopez, A., Blanco-Labra, A., Patthy, A., Sanchez, R., and Pongor, S. (1994) J. Biol. Chem. 269, 23675-23680). Its disulfide topology was confirmed by Edman degradation, and its three-dimensional solution structure was determined by two-dimensional 1H NMR spectroscopy at 500 MHz. Structural constraints (consisting of 348 nuclear Overhauser effect interproton distances, 8 backbone dihedral constraints, and 9 disulfide distance constraints) were used as an input to the X-PLOR program for simulated annealing and energy minimization calculations. The final set of 10 structures had a mean pairwise root mean square deviation of 0.32 A for the backbone atoms and 1.04 A for all heavy atoms. The structure of AAI consists of a short triple-stranded beta-sheet stabilized by three disulfide bonds, forming a typical knottin or inhibitor cystine knot fold found in miniproteins, which binds various macromolecular ligands. When the first intercystine segment of AAI (sequence IPKWNR) was inserted into a homologous position of the spider toxin Huwentoxin I, the resulting chimera showed a significant inhibitory activity, suggesting that this segment takes part in enzyme binding.

Amino Acid Sequence↗