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Biomedical subjects

Y Tu

Publications and source records attributed to Y Tu.

At least 37 records · Page 2Linked to original sources
PubMed2001

BMP-12 gene transfer augmentation of lacerated tendon repair.

Bone morphogenetic protein (BMP) 12 is a recently discovered member of the human BMP family. It is the human homolog of mouse growth/differentiation factor (GDF)-7. Previously we reported that injection of mesenchymal progenitor cells transferred with the BMP-12 gene into the muscles of nude mice induced tendon-like tissue formation. In this study, we further investigated the effect of BMP-12 gene transfer on tendon cells. We observed that adenovirus mediated in vitro BMP-12 gene transfer into chicken tendon cells increased type I collagen synthesis. No change in alkaline phosphatase activity was observed following BMP-12 gene transfer. We also determined that BMP-12 gene transfer into a complete tendon laceration chicken model resulted in a two-fold increase of tensile strength and stiffness of repaired tendons, indicating improved tendon healing in vivo. We conclude that BMP-12 gene transfer is a promising procedure for improving the tendon repair process.

Alkaline Phosphatase↗
PubMed2001

Formation of novel polymeric nanoparticles.

We have found that not only block copolymers but also ionomers can self-assemble in a selective solvent to form surfactant-free nanoparticles. The self-assembly can be induced by chemical reaction, polymer-polymer complexation, and microphase inversion in addition to the temperature. A recently developed microwave method for the preparation of uniform surfactant-free polymeric nanoparticles is also reviewed. Our results have revealed that for a given dispersion, the particle surface area occupied per stabilizer (surfactant, polymer chains, and ionic groups) is close to a constant.

Microspheres↗
PubMed2001

Knowledge of HIV/AIDS transmission and screening in United States blood donors.

BACKGROUND: Increased knowledge of HIV transmission and behavioral and test screening may encourage high-risk blood donors to self-defer. STUDY DESIGN AND METHODS: Knowledge of HIV transmission and screening and the association with demographics, screening test reactivity, and unreported deferrable risks (UDRs) was assessed by a 1998 anonymous mail survey sent to 92,581 blood donors, of whom 57 percent responded. Groups were compared by using weighted chi-square tests and logistic regression analysis. RESULTS: Four percent of the donors thought that it was very likely or somewhat likely for a person to contract HIV from donating blood, and 20 percent perceived a similar risk from blood transfusion. Only 60 percent of the donors knew that the available screening tests may not detect a recent infection. Thirty-seven percent either did not know or felt it was acceptable to donate blood to obtain HIV testing. Those most likely to answer knowledge questions incorrectly were more likely to have a higher prevalence of test reactivity or UDRs and to be <or=25 years old, members of a minority, less educated, non-US-born, or first-time donors. CONCLUSION: Innovative ways to increase donor understanding of the implications of risk behaviors and the limitations of current screening procedures should be developed. They might prevent high-risk individuals from donating blood.

Acquired Immunodeficiency Syndrome↗
PubMed2001

[Clinicopathologic study on chronic pancreatitis with diffuse irregular narrowing of the main pancreatic duct].

We studied the clinicopathologic features of 13 cases of chronic pancreatitis with diffuse irregular narrowing of the main pancreatic duct (MPD). It occurs frequently in relatively elder men. Diffuse irregular narrowing of the MPD and stenosis of the common bile duct on ERCP, and swelling of the pancreas on US/CT were detected in all cases. An autoimmune mechanism might be involved in the etiology at least in 5 patients with hypergammaglobulinemia and positive autoantibodies. Surgical therapy was performed in 8 patients and 3 patients were treated with steroids. No patients showed recurrence of pancreatitis. Histologic findings were characterized by diffuse lymphoplasmacytic infiltration with marked interstitial fibrosis in the pancreas, obliterated phlebitis of the pancreatic veins. Similar inflammatory process involved the bile duct and the gallbladder. These histologic findings were similar to those of multifocal fibrosclerosis. Chronic pancreatitis with diffuse irregular narrowing of the MPD is overlapped with autoimmune pancreatitis in many cases, but may be a variant of multifocal fibrosclerosis involving the pancreas in some cases.

Adult↗
PubMed2001

[Purification of conjugated bilirubin from human urine].

OBJECTIVES: To develop a simple, practical method with fine yield and purity for separating conjugated bilirubin(Bc) from a sustainable and facile material in order that it could serve as a calibrator for total and direct bilirubin determination. METHODS: Isolating Bc from urine of patients with obstructive jaundice by CHCl3: CH3CH2OH(1:1, V/V) followed by CNBr activated Sepharose 4B-HAS affinity chromatography, we analyzed the products by the use of Doumas J-G diazo method and HPLC, respectively. RESULTS: Determined by J-G diazo method, the crude product extracted by CHCl3: CH3CH2OH(1:1, V/V) yields 90.2 +/- 5.4%(n = 3) of urine Bc, the ratio of Bc to total dry weight being 67.9 +/- 6.4%(n = 3). The final product purified by affinity chromatography with the ratio of separation of 1.5, 1.737 and analyzed by HPLC has the yield of 46.9% and purity of 94.7%(BDG of 76.2%, BMG of 18.5%). CONCLUSION: The above data demonstrate that urine conjugated bilirubin can be successfully purified by CHCl3: CH3CH2OH extraction followed by Sephrose-HSA affinity chromatography with sufficient purity and output.

Bilirubin↗
PubMed2001

[Studies on the chemical compound of volatile oils from various species of Citrus grandis].

The volatile oils in Citrus grandis from various species were compared by GC-MS. The results showed that the content of volatile oil from Citrus grandis and Citrus grandis (L.) Osbek var. tomentosa Hort. was from 0.7% to 0.9%. Over 30 chemical compounds were identified from the volatile oils and the types of the compounds were almost the same. But gamma-terpinen could not be identified from Citrus grandis which was rich in Citrus gransis (L.) Osbeck var. tomentosa Hort.

Citrus↗
PubMed2000

The phosphatidylinositol 3-kinase/AKT kinase pathway in multiple myeloma plasma cells: roles in cytokine-dependent survival and proliferative responses.

Interleukin 6 (IL-6) and insulin-like growth factor I (IGF-I) induce proliferative and antiapoptotic responses in multiple myeloma (MM) plasma cells. Because these cytokines may activate the phosphatidylinositol 3-kinase (PI 3-K)/AKT kinase pathway in other cell types, we investigated the role of PI 3-K/AKT in MM cell responses. IGF-I effectively activated PI 3-K in 8226 and OCI-My5 MM cells, but IL-6 was ineffective. However, IL-6 successfully activated PI 3-K in AF-10 MM cells and IL-6-dependent MH.60 plasmacytoma/hybridoma cells. IGF-I also successfully activated PI 3-K in four of four MM patient specimens, and IL-6 activated PI 3-K in three of four specimens. Inhibition of PI 3-K activity with wortmannin or Ly294002 blocked the antiapoptotic effect of IGF-I and the proliferative effect of IL-6 in the myeloma cell lines. Furthermore, a dominant negative PI 3-K construct, expressed in AF-10 cells by adenoviral infection, also significantly inhibited the IL-6 proliferative response in MM cells. In correlation with activation of PI 3-K, IGF-I also effectively activated the AKT kinase in 8226 and OCI-My5 cells, and IL-6 activated AKT in AF-10 and MH.60 cells. However, although incapable of activating PI 3-K in 8226 and OCI-My5 cells, IL-6 successfully activated AKT in these MM lines, suggesting PI 3-K-independent mechanisms of AKT activation. The prevention of a myeloma cell proliferative response resulting from inhibition of PI 3-K activity was not associated with an inhibition of IL-6-dependent extracellular signal-regulated kinase (ERK) activation. These results support a role for the PI 3-K/AKT pathway in cytokine-dependent responses in myeloma cells, which is independent of any activation of the ERK pathway.

Androstadienes↗
PubMed2000

Inhibitory effect of cyclic guanosine 3',5'-monophosphate (cGMP) on the afferent resting activity in the cephalopod statocyst.

The effects of exo- and endogenous cGMP on the resting activity (RA) of afferent crista fibers were studied in isolated preparations of the statocysts of the cuttlefish Sepia officinalis and the squid Sepioteuthis lessoniana. Bath application of the membrane-permeable cGMP analogs 8-bromo-cGMP (B-cGMP) and N(2),2'-o-dibutyryl 3', 5'-cyclic guanosine monophosphate (dB-cGMP), and of the selective inhibitor of cGMP-phosphodiesterase zaprinast (ZAP), caused an inhibition of RA. The inhibitory effects of B-cGMP and dB-cGMP remained when the preparation was pre-treated with: (i) the guanylate cyclase inhibitors 1H-[1,2,4]oxadiazolo[4,3, -a]quinoxalin-1-one (ODQ) or cystamine (CYS); (ii) the adenylate cyclase inhibitors nicotinic acid (NIC-A), 2',3'dideoxyadenosine (DDA), or MDL-12330A (MDL); (iii) the guanylate cyclase inhibitor methylene blue (M-BLU) and the adenylate cyclase inhibitor MDL combined; or (iv) the nitric oxide (NO) synthase inhibitors N(G)-nitric-L-arginine methyl ester HCl (L-NAME) or N(G)-nitro-L-arginine (L-NOARG). These data indicate that cGMP, as an intracellular messenger, has a tonic inhibitory effect on the RA of afferent crista fibers in cephalopod statocysts.

Afferent Pathways↗
PubMed2000

Effects of nitric oxide donors on the afferent resting activity in the cephalopod statocyst.

The effects of bath applications of the nitric oxide (NO) donors sodium nitroprusside (SNP), diethylamine sodium (DEA), 3-morpholinosydnonimine (SIN-1), and S-nitroso-N-acetyl-penicillamine (SNAP) on the resting activity (RA) of afferent crista fibers were studied in isolated statocysts of the cuttlefish Sepia officinalis. The NO donors had three different effects: inhibition, excitation, and excitation followed by an inhibition. The SNAP analog N-acetyl-DL-penicillamine (xSNAP; with no NO moiety) had no effect. When the preparation was pre-treated with the NO synthase inhibitor N(G)-nitric-L-arginine methyl ester HCl (L-NAME), the NO donors were still effective. When the preparation was pre-treated with the guanylate cyclase inhibitors methylene blue (M-BLU) or cystamine (CYS), NO donors had only excitatory effects, whereas their effects were inhibitory only when pre-treatment was with the adenylate cyclase inhibitors nicotinic acid (NIC-A), 2',3'-dideoxyadenosine (DDA), or MDL-12330A. When pre-treatment was with a guanylate and an adenylate cyclase inhibitor combined, NO donors had no effect; in that situation, the RA of the afferent fibers remained and the preparation still responded to bath applications of GABA. Selective experiments with statocysts from the squid Sepioteuthis lessoniana and the octopod Octopus vulgaris gave comparable results. These data indicate that in cephalopod statocysts an inhibitory NO-cGMP and an excitatory NO-cAMP signal transduction pathway exist, that these two pathways are the key pathways for the action of NO, and that they have only modulatory effects on, and are not essential for the generation of, the RA.

Action Potentials↗
PubMed2000

Structure and energetics of the Si- SiO2 interface

Using a Monte Carlo approach, we identify low-energy structures for the (001)-oriented Si-SiO2 interface. The optimal interface structure found consists of an ordered array of Si-O-Si "bridges," with low strain energy. This structure explains several puzzling experimental observations.

Journal Article↗
PubMed2000

Involvement of ERK in BMP-2 induced osteoblastic differentiation of mesenchymal progenitor cell line C3H10T1/2.

The signaling mechanisms responsible for bone morphogenetic protein (BMP) induced osteoblast differentiation remains poorly understood. Previous research demonstrated that Smad proteins are the substrates and the mediators of BMP bound serine/threonine receptor kinase. In the present study, we examined the possible involvement of extracellular signal-regulated kinase (Erk) in the BMP induced osteoblast differentiation of mesenchymal progenitor cell C3H10T1/2. Our results indicate that BMP-2 inducement increased MAP kinase activity in mesenchymal progenitor cell line C3H10T1/2. Contrary to previous reports, this increased MAP kinase activity showed a latent but sustained pattern. Elevation of Erk1 and Erk2 protein levels was observed simultaneously. RT-PCR results demonstrated that the elevation of Erk protein level in BMP-2 induced cells was from the upregulation of mRNA expression. Furthermore, upregulated Erk proteins present enhanced phosphorylation. By using a dominant-negative Erk2 cell line, we demonstrated that nonfunctional Erk2 partially eliminated BMP-2 induced cell proliferation and ALP activity in the C3H10T1/2 cell. These results indicate that Erk is involved in BMP-2 induced osteoblast differentiation. The results also demonstrate that a latent and sustained signaling pattern exists in BMP induced signaling cascade.

Animals↗
PubMed2000

Expression and cellular localization of interleukin-6 mRNA in ovariectomized rats.

In order to observe the expression and cellular localization of interleukin-6 (IL-6) mRNA in bone tissue, ovaries of the rats were excised to develop osteoporosis model. The expression of IL-6 mRNA in bone tissues was detected by using dot blot hybridization assay and the cells producing IL-6 identified and localized by using in situ hybridization respectively. The results showed that the expression of IL-6 mRNA was significantly increased in the ovariectomized rats as compared with that in normal control rats and strong IL-6 mRNA hybridization signals were detected in lining cells, osteoblasts and osteocytes. It was suggested that loss of ovarian function induced in vivo osteoblast lineage increased IL-6 mRNA expression. IL-6 might play important roles in the development of bone loss following ovariectomy.

Animals↗
PubMed2000

Analysis of gene expression microarrays for phenotype classification.

Several microarray technologies that monitor the level of expression of a large number of genes have recently emerged. Given DNA-microarray data for a set of cells characterized by a given phenotype and for a set of control cells, an important problem is to identify "patterns" of gene expression that can be used to predict cell phenotype. The potential number of such patterns is exponential in the number of genes. In this paper, we propose a solution to this problem based on a supervised learning algorithm, which differs substantially from previous schemes. It couples a complex, non-linear similarity metric, which maximizes the probability of discovering discriminative gene expression patterns, and a pattern discovery algorithm called SPLASH. The latter discovers efficiently and deterministically all statistically significant gene expression patterns in the phenotype set. Statistical significance is evaluated based on the probability of a pattern to occur by chance in the control set. Finally, a greedy set covering algorithm is used to select an optimal subset of statistically significant patterns, which form the basis for a standard likelihood ratio classification scheme. We analyze data from 60 human cancer cell lines using this method, and compare our results with those of other supervised learning schemes. Different phenotypes are studied. These include cancer morphologies (such as melanoma), molecular targets (such as mutations in the p53 gene), and therapeutic targets related to the sensitivity to an anticancer compounds. We also analyze a synthetic data set that shows that this technique is especially well suited for the analysis of sub-phenotype mixtures. For complex phenotypes, such as p53, our method produces an encouragingly low rate of false positives and false negatives and seems to outperform the others. Similar low rates are reported when predicting the efficacy of experimental anticancer compounds. This counts among the first reported studies where drug efficacy has been successfully predicted from large-scale expression data analysis.

Algorithms↗
PubMed2000

Immunohistochemical localization of pancreatic secretory trypsin inhibitor in malignant pancreatic endocrine tumors.

Differentiation of benign from malignant pancreatic endocrine tumors by existing clinical, biochemical, histologic, and cytologic criteria is difficult. We immunohistochemically localized pancreatic secretory trypsin inhibitor (PSTI) in 28 pancreatic endocrine tumors (13 benign, 15 malignant). PSTI-immunoreactive cells were detected in nine endocrine tumors. Immunoreactivity in these tumors was detected in nearly all tumor cells in five cases, scattered cells in two cases, and a few cells in two cases. All positive cases were malignant, and eight were equal to or larger than 10 cm. Serum concentrations of PSTI were markedly elevated in the two patients so tested. PSTI may be a specific immunohistochemical marker for malignant pancreatic endocrine tumors.

Adult↗
PubMed2000

[Transgenic mice model of human hepatitis B virus x gene].

OBJECTIVE: To set up a human hepatitis B virus x (HBx) gene transgenic model. METHODS: The model was set up by microinjection, the integration and expression of the founders were identified by molecular hybridization. RESULTS: A 1,800 bp DNA fragment containing the human HBx promoter and genomic DNA was microinjected into the male pronucleus of the fertilized eggs of mice. Three hundred and thirty-eight eggs survived from microinjection were transplanted into the oviduct of 16 pseudopregnant female, 12 pseudopregnant mice got pregnant and gave birth to 74 pups. Genomic DNA were extracted from the tails of the pups, Southern blot hybridization was used for determination of the integration of human HBx gene. The 1,800 bp microinjected fragment was used as the probe, 17 mice (founders) were identified of the integration of human HBx gene. Total RNA were extracted from the livers of the founders, all 17 founders were identified of the expression of human HBx gene by using Northern blot hybridization. CONCLUSIONS: These results may provide animal models for studying on the correlation between chronic HBV infection and the development of hepatocellular carcinoma.

Animals↗
PubMed2000

[The determination of ofloxacin by fluorescence spectrophotometry].

This paper reports the assay of ofloxacin by fluorescence spectrophotometry. The fluorescence strength of ofloxacin is proportional to its concentration within the range from 0.500-25.0 ppm. The linear regression coefficient equals to 0.9999, and the recovery ratio is 99.0%. The results of determination for the samples of ofloxacin capsule from China and Japan are very close to that determined by the ultraviolet spectrophotometry, there isn't any obviously difference which was examined by Student's test. This method is both simplicity and accuracy, also it needs only one kind of reagent. It's believable that this method would be suitable for the use in clinical medicine and pharmaceutical industry.

Anti-Infective Agents↗