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Journal Article↗
Biomedical subjects
Y Tu
Publications and source records attributed to Y Tu.
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↗
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↗
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↗
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↗
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↗
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↗
[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↗
[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↗
[The UV-Vis spectrographic and electrochemical study on the beta-cyclodextrin inclusion compound of 3,3',5,5'-tetramethylbenzidine].
This paper reports the results of UV-Vis spectrographic and electrochemical studying on the beta-cyclodextrin inclusion compound of 3,3',5,5'-tetramethylbenzidine (TMB). The molecules of TMB show better redox performance after they were included in the cavities of beta-cyclodextrin, especially while there were the redox enzyme. The composition of oxidization product in the inclusion compound is more single. The results were also revealed by the obviously increasing of voltammetrical current when this inclusion compound was modified on the electrode surface. It is reasonable to conclude that the formation of TMB-beta-cyclodextrin inclusion compound would enhance the sensitivity of those analytical methods based on the redox reaction of TMB.
Benzidines↗
Palmitoylation of a conserved cysteine in the regulator of G protein signaling (RGS) domain modulates the GTPase-activating activity of RGS4 and RGS10.
RGS4 and RGS10 expressed in Sf9 cells are palmitoylated at a conserved Cys residue (Cys(95) in RGS4, Cys(66) in RGS10) in the regulator of G protein signaling (RGS) domain that is also autopalmitoylated when the purified proteins are incubated with palmitoyl-CoA. RGS4 also autopalmitoylates at a previously identified cellular palmitoylation site, either Cys(2) or Cys(12). The C2A/C12A mutation essentially eliminates both autopalmitoylation and cellular [(3)H]palmitate labeling of Cys(95). Membrane-bound RGS4 is palmitoylated both at Cys(95) and Cys(2/12), but cytosolic RGS4 is not palmitoylated. RGS4 and RGS10 are GTPase-activating proteins (GAPs) for the G(i) and G(q) families of G proteins. Palmitoylation of Cys(95) on RGS4 or Cys(66) on RGS10 inhibits GAP activity 80-100% toward either Galpha(i) or Galpha(z) in a single-turnover, solution-based assay. In contrast, when GAP activity was assayed as acceleration of steady-state GTPase in receptor-G protein proteoliposomes, palmitoylation of RGS10 potentiated GAP activity >/=20-fold. Palmitoylation near the N terminus of C95V RGS4 did not alter GAP activity toward soluble Galpha(z) and increased G(z) GAP activity about 2-fold in the vesicle-based assay. Dual palmitoylation of wild-type RGS4 remained inhibitory. RGS protein palmitoylation is thus multi-site, complex in its control, and either inhibitory or stimulatory depending on the RGS protein and its sites of palmitoylation.
Animals↗
Cloning, expression and characterization of a novel human Ras-related protein that is regulated by glucocorticoid hormone.
Ras proteins are a family of guanine nucleotide (GDP and GTP)-binding proteins that play central roles in essential signal transduction pathways. We have isolated in a yeast two-hybrid screen a human cDNA encoding a new protein that is highly homologous (98% identical at the protein level) to mouse DexRas1, a member of the Ras superfamily. The human DexRas1 is expressed in a variety of tissues including heart, brain, placenta, lung, liver, skeletal muscle, kidney and pancreas, with the strongest expression in the heart. Using human fibrosarcoma HT-1080 cells as a model system, we show that the expression of human DexRas1 is stimulated by dexamethasone, suggesting a role of human DexRas1 in dexamethasone-induced alterations in cell morphology, growth and cell-extracellular matrix interactions.
Amino Acid Sequence↗
Effects of L-arginine on the afferent resting activity in the cephalopod statocyst.
The effects of bath application of the nitric oxide (NO) precursor L-arginine (L-ARG) on the resting activity (RA) of afferent crista fibers were studied in isolated statocysts of the cuttlefish Sepia officinalis under various experimental conditions. L-ARG (threshold 10(-7) M) had three different effects: inhibition, excitation, and excitation followed by an inhibition; only the inhibitory effect of L-ARG was dose-dependent. D-Arginine (D-ARG) had no effect. When the preparation was pre-treated with NO synthase inhibitors (N(G)-Nitric-L-arginine methyl ester HCl (L-NAME), N(G)-Nitro-L-arginine (L-NOARG)), both the inhibitory and the excitatory effects of L-ARG significantly decreased at higher concentrations (10(-5 to -4) M), or were completely blocked at lower concentrations (10(-7 to -6) M), of L-ARG. When the preparation was pre-treated with guanylate cyclase inhibitors (1H-[1,2, 4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ), methylene blue (M-BLU), cystamine (CYS)), L-ARG had only excitatory effects, whereas its effects were only inhibitory when the preparation was pre-treated with adenylate cyclase inhibitors 2',3'-dideoxyadenosine (DDA), MDL-12330A (MDL), nicotinic acid (NIC-A)). L-ARG had no effects when the pre-treatment was with a guanylate cyclase inhibitor and an adenylate cyclase inhibitor combined; in that situation, the RA of the afferent fibers remained. These data indicate that in cephalopod statocysts, a cGMP and a cAMP signal transduction pathway (presumably via the generation of NO) are responsible for the effects of L-ARG on the RA of crista afferent fibers. They also indicate that the L-ARG-cGMP pathway is the dominant pathway and is inhibitory, and that both pathways have only modulatory effects on, but are not essential for, the generation of the RA.
Action Potentials↗
Myosin-induced autoimmune myocarditis in BALB/C mice.
Experimental mice were immunized with cardiac myosin and complete Freund's adjuvant (CFA) on days 0, 7 and 30 and control mice were immunized with CFA. Sera and myocardium samples were harvested on days 15, 21 and 120 after the first immunization. Pathological findings demonstrated that there were necrosis and inflammatory infiltration in acute stage and fibrosis mainly in chronic stage of experimental group. Anti-myosin antibodies were also found in sera of experimental mice, but not in control group. Our study showed that cardiac myosin served as an autoantigen to provoke autoimmunity and lead to the transformation of VMC into DCM.
Animals↗
Molecular characterization of gene expression changes in ROS 17/2.8 cells cultured in diffusion chambers in vivo.
Transplantation of diffusion chambers (DC) containing osteoblast-like cells to extraskeletal sites has been highly studied and proven to be a useful technique to investigate the process of osteoblast differentiation and bone formation. To investigate the molecular basis of osteogenesis in DC, we examined the temporal pattern of gene expression of the proliferation marker histone H4, immediate early response genes (IEGs), c-fos, c-jun, c-myc, osteoblast phenotype-associated genes, osteocalcin (OC), osteopontin (OP), type I collagen (COL1A1), alkaline phosphatase (ALP), parathyroid hormone receptor (PTHR) and matrix modifying enzyme, matrix metalloproteinase-9 (MMP-9). DC containing ROS 17/2.8 were implanted intraperitoneally into rat hosts and cultured in vivo for various times up to 56 days. Histological analysis of von Kossa stained sections of the DC contents showed a well-organized connective tissue and the production of mineralized matrices/nodules. In contrast, histological examination of DC containing Rat-2 fibroblast cells revealed the lack of an organized mineralized matrix. Molecular analysis of DC containing ROS 17/2.8 cells at 0, 3, 10, 28, and 56 days demonstrated a time-dependent decrease in DNA content associated with cell death. In the surviving cells, an increase in histone H4 mRNA (consistent with an increase in cell proliferation) was evident by 3-10 days and thereafter expression returned to control levels. In vitro, ROS 17/2.8 cells expressed detectable levels of c-fos, c-jun, c-myc, OC, OP, ALP, COL1A1, and PTHR but not MMP-9. In vivo, the expression of c-fos increased 2-fold in 3-28 days and by 56 days was 4-5 fold above control levels. In 3-10 days, c-jun expression increased 1.6-1.8-fold above control levels. In contrast, by day 28, c-jun expression decreased to control levels, but increased to 2.1-fold above control by 56 days. c-myc mRNA expression increased 3-fold within 3 days and then dropped to below control values by 10-56 days. After transplantation in vivo, the expression of OC and PTHR decreased to undetectable levels. Similarly, ALP mRNA decreased to </=28% of preimplantation values. In contrast, OPN mRNA levels increased up to 7-fold by day 10 and thereafter, returned to 1.7-fold above control values. COL1A1 mRNA decreased 2-fold at day 3 and increased to 3.5-, 1.6-, and 2.8-fold above control at days 10, 28, and 56, respectively. MMP-9 levels increased 5- to 10-fold by days 3-10, but fell to undetectable levels by 28-56 days. These results indicate that the formation of mineralized matrix (bone nodules) seen in the 56-day DC of ROS 17/2.8 cells was preceded by coordinate temporal expression of IEGs, matrix proteins, and matrix-modifying enzymes. Additionally, these results substantiate that measurement of molecular parameters in tissues formed by cells incubated in DC in vivo may be a useful predictor of the osteogenic process.
Animals↗
Analysis of donor return behavior. Retrovirus Epidemiology Donor Study.
BACKGROUND: Efforts to provide a safe, adequate blood supply have been inhibited by persistent shortages attributed to a lack of motivation on the part of the general public and inefficiency in recruiting processes. This study examined whether frequency of donations and/or timing of subsequent donations by first-time donors related to donor demographics. STUDY DESIGN AND METHODS: Characteristics of 879,816 first-time donors making at least one whole-blood donation were analyzed. Cox proportional-hazards regression models evaluated the first 10 return times separately, and a recurrent-event Cox model was applied to simultaneously evaluate the first five returns. RESULTS: The shorter the donation interval between the first two donations, the more likely the donor was to make subsequent donations. The proportion of repeat donors increased with education level. Rate of donation increased with age and education. The recurrent-event Cox regression model showed that Rh-negative donors, older donors, and donors who had completed college had higher donation return rates. CONCLUSION: Time to return for second donation was associated with total number of donations made and with return rate for subsequent returns. Age was the strongest predictor of high donation frequency and early-return rate. Relationships between interdonation interval and the number of future donations may prove useful in understanding return behavior and developing donor recruitment and retention strategies.
Adult↗
Effect of bone morphogenetic protein-12 gene transfer on mesenchymal progenitor cells.
Recombinant adenovirus mediated human bone morphogenetic protein-12 gene transfer induced tendon and cartilage-like tissue formation in vivo. The recombinant adenovirus with the human bone morphogenetic protein-12 gene was constructed, and mature human bone morphogenetic protein-12 expression mediated by adenovirus gene transfer was detected by specific antibody. Unlike bone morphogenetic protein-2 gene transfer, bone morphogenetic protein-12 gene transferred mesenchymal progenitor cell line C3H 10T1/2 showed no change of alkaline phosphatase activity, which is the mark of cell differentiation into osteoblastic phenotype. Injection of bone morphogenetic protein-12 gene transferred C3H 10T1/2 cells into nude mice thigh muscles induced tendon and cartilage-like tissue formation. The results indicate bone morphogenetic protein-12 has different effects on mesenchymal progenitor cell differentiation, and it may influence the cell differentiation into a nonosteoblast lineage.
Adenoviridae↗
Hypoplasia of ventral pancreas shows a threadlike ventral pancreatic duct.
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Aged↗