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Jian Yu

Publications and source records attributed to Jian Yu.

At least 37 records · Page 2Linked to original sources
PubMed2005

[EphB2-Fc promotes activation of endogenous neural stem cells after cerebral cortex infarction: experimental with hypertensive rats].

OBJECTIVE: To explore the effects of intraventricular injection of EphB2-Fc on activation of inherent neural stem cells after cerebral cortex infarction. METHODS: Stroke-prone renovascular hypertension model was established in 96 SD rats by two-kidney, two-clip method. Middle cerebral artery occlusion (MCAO) model was established in 72 of these 96 stroke-prone renovascular hypertensive rats and the other 24 rats were used as sham operation group. Then the 72 rats were randomly divided into 3 equal groups: cerebral infarction group without any treatment after the MCAO, MCAO + EphB2-Fc group undergoing stereotaxical infusion of EphB2-Fc at the dose of 20 microl x 200 microg/ml into the lateral ventricle 4 days after the distal ligation of right middle cerebral artery, and MCAO + IgG-Fc group undergoing stereotaxical infusion of IgG-Fc at the dose of 20 microl x 200 microg/ml into the lateral ventricle 4 days after the distal ligation of right middle cerebral artery. By the ends of the first and fourth weeks after the MCAO procedure 12 rats from each group were killed and their brains were taken out to undergo in situ hybridization, immunohistochemistry and Western blotting analysis in order to determine the expression of EphB2 protein and mRNA, nestin and polysialic acid-neural cell adhesion molecule (PSA-NCAM). RESULTS: One week after the distal ligation of right middle cerebral artery, the EphB2 protein and mRNA expression levels in the ipsilateral cortex and subventricular zone (SVZ) of the cerebral infraction group were both lower than those of the sham operation group (P < 0.05), such levels of the MCAO + EphB2-Fc group were higher than those of the MCAO + IgG-Fc group (both P < 0.05), but there was no significant difference between the cerebral infraction group and IgG-Fc group (both P > 0.05), and there were no differences in such levels between the cerebral infarction group and MCAO + IgG-Fc group (both P > 0.05); the nestin and PSA-NCAM expression levels in the ipsilateral SVZ of the cerebral infraction group were both higher than those of the sham operation group (both P < 0.05), such levels of the MCAO + EphB2-Fc group were both higher than those of the MCAO + IgG-Fc group (both P < 0.05), and migration of PSA-NCAM positive cells to corpus callosum could be seen. Four weeks after, there were no significant differences in the expression levels of EphB2 protein and mRNA among different groups (all P > 0.05), the nestin and PSA-NCAM expression levels in the ipsilateral SVZ decreased in all groups, there were no significant differences in the expression of nestin among all groups, but the PSA-NCAM expression in the ipsilateral SVZ of the cerebral infraction group was still higher than that of the sham operation group. CONCLUSION: Disruption of EphB2 signal promotes the proliferation and migration of endogenous neural stem cells in the SVZ after cerebral cortex infarction.

Animals↗
PubMed2005

Adsorption and analysis of the insecticides thiamethoxam and indoxacarb in hawaiian soils.

A method was developed for the simultaneous extraction and analysis of the insecticides indoxacarb and thiamethoxam from five Hawaiian soils. Using pressurized fluid extraction followed by liquid chromatography, optimized recoveries from the five soils were obtained ranging from 80% +/- 5 to 101% +/- 10 for thiamethoxam, and 83% +/- 6 to 106% +/- 7 for indoxacarb. Aging studies also showed strong binding of indoxacarb to all soils tested after 30 days, while thiamethoxam remained quite available for extraction during the length of the study (90 days). Freundlich constant (K(f)) and empirical value (n) for thiamethoxam sorption on Lihue soil were 0.007391 mmol((1-1/)(n)).L(1/)(n).g(-1) and 1.1377, respectively; K(f) and n were 0.007844 mmol((1-1/)(n)).L(1/)(n).g(-1) and 0.8473, respectively, on Wahiawa soil. The organic carbon adsorption constant (Koc) of thiamethoxam was 0.53 in Lihue soil and 0.23 in Wahiawa soil.

Adsorption↗
PubMed2005

The transcriptional targets of p53 in apoptosis control.

Induction of apoptosis is an essential function of p53 as a tumor suppressor. p53 can activate its downstream targets in a sequence specific manner to induce apoptosis. Most tumor derived p53 mutants are deficient in transcription activation as well as apoptosis induction. p53 can activate genes in the extrinsic and intrinsic pathways through transcription-dependent mechanisms or induce apoptosis through transcription-independent mechanisms. Several proapoptotic Bcl-2 family proteins, such as PUMA and Noxa, are shown to be critical mediators of p53-dependent apoptosis. The selective activation of the apoptotic targets of p53 is modulated by transcription coactivators. The induction of apoptotic genes alone sometimes is not sufficient to induce apoptosis, as the cell cycle arrest mediated by the cell cycle inhibitors dominates apoptosis. Preventing the induction of p21 under these conditions can drive the cells towards apoptosis. Understanding how p53 controls apoptosis through its targets may lead to discoveries of novel therapeutics to combat cancer and other diseases.

Animals↗
PubMed2005

PUMA overexpression induces reactive oxygen species generation and proteasome-mediated stathmin degradation in colorectal cancer cells.

Increased amounts of reactive oxygen species (ROS) induce apoptosis in mammalian cells. PUMA (P53 up-regulated modulator of apoptosis), a mitochondrial proapoptotic BH3-only protein, induces rapid apoptosis through a Bax- and mitochondria-dependent pathway. However, the molecular basis of PUMA-induced apoptosis is largely not understood. Using a combination of biophysical and biochemical methods and PUMA-inducible colorectal cells, DLD-1.PUMA, we showed that (a) PUMA-induced apoptosis is dose and time dependent; (b) PUMA-induced apoptosis is directly associated with ROS generation; (c) diphenyleneiodonium chloride, a ROS blocker, or BAX-inhibiting peptide, a suppressor of BAX translocation, decreased ROS generation and apoptosis in DLD-1.PUMA cells; (d) overexpression of PUMA induced up-regulation (>1.34-fold) of peroxiredoxin 1 and down-regulation (by 25%) of stathmin through proteasome-mediated degradation; and (e) hydrogen peroxide down-regulated stathmin and disrupted the cellular microtubule network. Our findings indicate that PUMA induces apoptosis, in part, through the BAX-dependent generation of superoxide and hydrogen peroxide. ROS overproduction and oxidative stress induce proteome-wise alterations, such as stathmin degradation and disorganization of the cell microtubule network, in apoptotic cells.

Apoptosis↗
PubMed2005

Cultured human embryonic neocortical cells survive and grow in infarcted cavities of adult rat brains and interconnect with host brain.

BACKGROUND: There are no reports on exnografting cultured human fetal neocortical cells in this infracted cavities of adult rat brains. This study was undertaken to observe whether cultured human cortical neurons and astrocytes can survive and grow in the infarcted cavities of adult rat brains and whether they interconnect with host brains. METHODS: The right middle cerebral artery was ligated distal to the striatal branches in 16 adult stroke-prone renovascular hypertensive rats. One week later, cultured cells from human embryonic cerebral cortexes were stereotaxically transferred to the infarcted cavity of 11 rats. The other 5 rats receiving sham transplants served as controls. For immunosuppression, all transplanted rats received intraperitoneal injection of cyclosporine A daily starting on the day of grafting. Immunohistochemistry for glial fibrillary acidic protein (GFAP), synaptophysin, neurofilament, and microtubule associated protein-2 (MAP-2) was performed on brain sections perfused in situ 8 weeks after transplantation. RESULTS: Grafts in the infarcted cavities of 6 of 10 surviving rats consisted of bands of neurons with an immature appearance, bundles of fibers, and GFAP-immunopositive astrocytes, which were unevenly distributed. The grafts were rich in synaptophysin, neurofilament, and MAP2-positive neurons with long processes. The graft/host border was diffuse with dendrites apparently bridging over to the host brain, into which neurofilament immunopositive fibers protruded. CONCLUSION: Cultured human fetal brain cells can survive and grow in the infarcted cavities of immunodepressed rats and integrate with the host brain.

Animals↗
PubMed2005

Impact of thymectomy on the peripheral T cell pool in rhesus macaques before and after infection with simian immunodeficiency virus.

The goal of this study was to define, by surgical removal of the thymus in juvenile rhesus macaques, the role of the thymus in peripheral T cell homeostasis and to assess the significance of thymic output in SIV infection. By monitoring the changes in phenotypic T cell markers as well as in the numbers of TCR excisional circles--a recently described marker for recent thymic emigrants--following thymectomy, we present evidence that surgical thymectomy in juvenile macaques results in a faster decay of peripheral CD4(+) cells, but does not cause a substantial shift in CD45RA(+) and CD45RA(-) populations. We were able to measure a thymic output of 0.32% and 0.21% per day of CD4(+) and CD8(+) cells, respectively. No compensatory extra-thymic source was detected in lymphoid tissues, although there was a small compensatory increase in T cell proliferation in the peripheral T cell pool. After SIV infection, thymectomized animals did not have higher viral loads, greater T cell decay, or faster disease progression. We therefore conclude that peripheral destructive processes, rather than a loss of thymic output, appear to be the main causes of T cell depletion in SIV infection.

Animals↗
PubMed2005

Activity and stability of laccase in conjugation with chitosan.

Laccase is one of a few enzymes that can directly reduce oxygen into water under ambient conditions, while oxidizing a variety of aromatic compounds. Its conjugation with chitosan generates a pH-sensitive functional biomaterial that changes its solubility in response to pH variation. The molecular conjugation between laccase and chitosan of different molecular mass was investigated with a carbodiimide reaction to understand the mechanism of the enzyme's activity loss during conjugation. With 81-93% laccase being conjugated, a moderate activity loss (16-28% less than the initial activity) was observed in conjugation solution. A second severe activity loss (63-78% less than the conjugated activity) occurred during a cycle of phase change consisting of precipitation, centrifugation and re-dissolution of the enzyme-chitosan conjugates. The chitosan molecular size has little effect on the first moderate activity loss in the conjugation reaction, but visible effect on the substantial activity loss associated with phase change. Small chitosan molecules gave high residual activity. The conjugated laccase exhibited a high stability in the following repeated phase changes and had the same temperature and pH profile as those of free laccase. Compared to free laccase, the conjugated laccase had a similar affinity (Km), but reduced turnover (kcat) that was adversely affected with increase of molecular mass of chitosan.

Biocompatible Materials↗
PubMed2005

A note on the ICS algorithm with corrections and theoretical analysis.

In [1], Ozdemir and Akarun proposed an intercluster separation (ICS) fuzzy clustering algorithm. The ICS algorithm is useful in combined quantization and dithering. However, there are two errors in the update equations for the ICS algorithm. This correspondence first points out these errors and gives their corrections. Since the parameters m, c, and gamma are important factors in the performance of ICS, we also conduct a theoretical analysis of these ICS parameters. In order to analyze the parameters in ICS, we devise a theorem for the calculation of the Hessian matrix from the ICS objective function. We establish the fixed-point property of ICS based on the decomposition of the Hessian matrix and then analyze the effect of the parameters. Finally, we propose a numerical approach in choosing the appropriate parameters m and gamma for ICS. These experimental results give a better numerical perspective on the effect of parameters in ICS and have conclusions consistent with our theoretical analysis.

Algorithms↗
PubMed2005

Comments on "The multisynapse neural network and its application to fuzzy clustering".

In the above-mentioned paper, Wei and Fahn proposed a neural architecture, the multisynapse neural network, to solve constrained optimization problems including high-order, logarithmic, and sinusoidal forms, etc. As one of its main applications, a fuzzy bidirectional associative clustering network (FBACN) was proposed for fuzzy-partition clustering according to the objective-functional method. The connection between the objective-functional-based fuzzy c-partition algorithms and FBACN is the Lagrange multiplier approach. Unfortunately, the Lagrange multiplier approach was incorrectly applied so that FBACN does not equivalently minimize its corresponding constrained objective-function. Additionally, Wei and Fahn adopted traditional definition of fuzzy c-partition, which is not satisfied by FBACN. Therefore, FBACN can not solve constrained optimization problems, either.

Algorithms↗
PubMed2005

General C-means clustering model.

Partitional clustering is an important part of cluster analysis. Based on various theories, numerous clustering algorithms have been developed, and new clustering algorithms continue to appear in the literature. It is known that Occam's razor plays a pivotal role in data-based models, and partitional clustering is categorized as a data-based model. However, no relation had previously been discovered between Occam's razor and partitional clustering, as we discuss in this paper. The three main contributions of this paper can be summarized as follows: 1) According to a novel definition of the mean, a unifying generative framework for partitional clustering algorithms, called a general c-means clustering model (GCM), is presented and studied. 2) Based on the local optimality test of the GCM, the connection between Occam's razor and partitional clustering is established for the first time. As its application, a comprehensive review of the existing objective function-based clustering algorithms is presented based on GCM. 3) Under a common assumption about partitional clustering, a theoretical guide for devising and implementing clustering algorithm is discovered. These conclusions are verified by numerical experimental results.

Algorithms↗
PubMed2005

Recombinant modified vaccinia virus Ankara expressing the spike glycoprotein of severe acute respiratory syndrome coronavirus induces protective neutralizing antibodies primarily targeting the receptor binding region.

Immunization with a killed or inactivated viral vaccine provides significant protection in animals against challenge with certain corresponding pathogenic coronaviruses (CoVs). However, the promise of this approach in humans is hampered by serious concerns over the risk of leaking live severe acute respiratory syndrome (SARS) viruses. In this study, we generated a SARS vaccine candidate by using the live-attenuated modified vaccinia virus Ankara (MVA) as a vector. The full-length SARS-CoV envelope Spike (S) glycoprotein gene was introduced into the deletion III region of the MVA genome. The newly generated recombinant MVA, ADS-MVA, is replication incompetent in mammalian cells and highly immunogenic in terms of inducing potent neutralizing antibodies in mice, rabbits, and monkeys. After two intramuscular vaccinations with ADS-MVA alone, the 50% inhibitory concentration in serum was achieved with reciprocal sera dilutions of more than 1,000- to 10,000-fold in these animals. Using fragmented S genes as immunogens, we also mapped a neutralizing epitope in the region of N-terminal 400 to 600 amino acids of the S glycoprotein (S400-600), which overlaps with the angiotensin-converting enzyme 2 (ACE2) receptor-binding region (RBR; S318-510). Moreover, using a recombinant soluble RBR-Fc protein, we were able to absorb and remove the majority of the neutralizing antibodies despite observing that the full S protein tends to induce a broader spectrum of neutralizing activities in comparison with fragmented S proteins. Our data suggest that a major mechanism for neutralizing SARS-CoV likely occurs through blocking the interaction between virus and the cellular receptor ACE2. In addition, ADS-MVA induced potent immune responses which very likely protected Chinese rhesus monkeys from pathogenic SARS-CoV challenge.

Angiotensin-Converting Enzyme 2↗
PubMed2005

The expression of telomeric proteins and their probable regulation of telomerase during the differentiation of all-trans-retinoic acid-responsive and -resistant acute promyelocytic leukemia cells.

Telomerase activity has been linked to retinoid induction of tumor cell differentiation, and the patterns of telomerase expression are different in the 2 pathways of acute promyelocytic leukemia (APL) cell differentiation: the retinoic acid receptor 3 (RAR3)-dependent and the retinoic X receptor 3 (RXR3)-dependent pathways. Still, whether telomeric proteins respond to retinoid treatment is not clear. If they do, how they would respond and how they would interfere in telomerase regulation during differentiation are also unclear. Using all-trans-retinoic acid (ATRA)-sensitive and -resistant APL cell lines NB4, NB4-R1, and NB4-R2, we analyzed a panel of telomeric proteins, including TRF1, PINX1, TANK1, and TANK2, at the messenger RNA (mRNA) and protein expression levels during the differentiation of these cell lines in the 2 pathways. Our analyses showed that both mRNA and protein expression of TRF1 remained stable during NB4 and NB4-R1 cell differentiation but slightly increased in NB4-R2 cells, suggesting that TRF1 may have different functions in the RAR3- and RXR3-dependent pathways. The stable expression of TRF1 may be because telomere length remains unchanged. Pinx1 mRNA expression was tightly correlated with telomerase reverse transcriptase (hTERT) mRNA expression during differentiation. Variation in Pinx1 expression may be a reaction induced by hTERT expression variation. TANK1 mRNA expression and TANK1 protein levels were both down-regulated in all 3 APL cell lines at a later period of differentiation, suggesting that TANK1 may positively regulate telomerase activity and that both RAR3- and RXR3-dependent pathways may exert this regulation.TANK2 expression levels remained stable in all 3 APL cell lines during differentiation, showing that TANK2 may have little effect on telomerase. Thus, our studies provide an outline of the dynamics of telomeric protein expression and the probable regulatory effects of these proteins on telomerase during the differentiation of ATRA-responsive and -resistant APL cells.

Antineoplastic Agents↗
PubMed2005

Study on the expression and mutation of human telomeric repeat binding factor (hTRF1) in 10 malignant hematopoietic cell lines.

OBJECTIVE: Detecting the expression and mutation of human telomeric repeat binding factor (hTRF1) in 10 malignant hematopoietic cell line cells on the base of determining its genomic structure and its four pseudogenes to clarify if hTRF1 mutation is one of the factors of the activation of telomerase. METHODS: hTRF1cDNA sequences were obtained from GenBank, its genome structure and pseudogenes were forecasted by BLAST and other biology information programs and then testified by sequencing. Real-time RT-PCR was used to detect the expression of hTRF1mRNA in 10 cell line cells, including myelogenous leukemia cell lines K562, HL-60, U-937, NB4, THP-1, HEL and Dami; lymphoblastic leukemia cell lines 6T-CEM, Jurkat and Raji. Telomerase activities of cells were detected by using telomeric repeat amplification (TRAP)-ELISA protocol. PCR and sequencing were used to detect mutation of each exon of hTRF1 in 10 cell line cells. RESULTS: hTRF1 gene, mapped to 8q13, was divided into 10 exons and spans 38.6 kb. Four processed pseudogenes of hTRF1 located on chromosome 13, 18, 21 and X respectively, was named as PsihTRF1-13, PsihTRF1-18, PsihTRF1-21 and PsihTRF1-X respectively. All cell line cells showed positive telomerase activity. The expression of hTRF1 was significantly lower in malignant hematopoietic cell lines cells (0.0338, 0.0108-0.0749) than in normal mononuclear cells (0.0493, 0.0369-0.128) (P=0.004). But no significant mutation was found in all exons of hTRF1 in 10 cell line cells. Four variants were found in part of intron 1, 2 and 8 of hTRF1. Their infection on gene function is unknown and needs further studies. CONCLUSION: hTRF1 mutation is probably not one of the main factors for telomerase activation in malignant hematopoietic disease.

Base Sequence↗
PubMed2005

[Mycophenolic acid induced apoptosis in T lymphocytic cells Molt-4 and its mechanism].

OBJECTIVE: To determine whether mycophenolic acid (MPA) exerts an apoptotic effect on human leukemic T cells Molt-4 and to elucidate its possible mechanism. METHODS: Cell morphology, DNA fragmentation, cell cycle,percentage of annexin V positive cells and enzymatic activity of caspase-3 were measured by microscopic, electrophoretic and flow cytometric techniques respectively. Human leukemic B cell line Raji was used as control. RESULT: MPA could induce apoptosis of Molt-4 cells with dose-and time-dependent manners; cells were blocked in the S phase. The activity of caspase-3 was enhanced in a dose-dependent manner in Molt-4 cells treated with MPA for 24 h. MPA could not induce apoptosis in Raji cells. CONCLUSION: MPA can induce apoptosis in Molt-4 cells which may be involved in the activation of caspase-3.

Antibiotics, Antineoplastic↗
PubMed2005

[Determination of twenty one elements in lithium hexafluorophosphate by ICP-AES].

One gram (+/- 0.0001 g) of lithium hexafluorophosphate was weighed exactly under dry atmosphere and was dissolved with an adequate amount of dimethyl carbonate (DMC). After the sample solution was pretreated with a series of methods, Be, Cu, Pb, Ca, Zr, Co, Mg, V, Ti, Mo, Ni, Mn, Sr, Zn, K, Al, Ba, Cd, Fe, Cr and Na were determined by ICP-AES. The results show that the recoveries of standard addition were 93.3%-102.1%, and the relative standard deviations (n = 11) were 0%-3.56%. The method is efficient, accurate and easy to operate. It has been applied to the determination of lithium hexafluorophosphate products with satisfactory results.

Calcium↗
PubMed2005

[An experimental study on proliferative effects and apoptotic effects of podophyllic acid in K562 cells].

OBJECTIVE: To study the effects of podophyllic acid on proliferation and apoptosis in human leukemia K562 cells. METHODS: The inhibitory effects of podophyllic acid on K562 cells were investigated by clony-formation and MTT colorimetric assay. The apoptotic effects were observed by FCM. RESULTS: Podophylic acid could inhibit the proliferation of K562 cells and there were a significant difference between experimental and control groups (P < 0.01). There was a marked positive correlation between drug concentration and the inhibitory rates. Podophyllic acid could induce apoptosis of K562 cells. When K562 cells were treated with 5.0 microg/ml podophyllic acid for 48 hours, apoptosis occurred to the largest extent. The apoptosis rate of podophyllic acid was 33.5%. CONCLUSIONS: Podophyllic acid has antitumor effect, but the change of structure affects the function of derivatives of podophylloxin greatly.

Antineoplastic Agents, Phytogenic↗
PubMed2005

[The study of recombinant plasmid of NP, HN and F gene therapy on the transplantable model of human laryngeal squamous carcinoma in nude mice].

OBJECTIVE: To explore a new method in the gene therapy of human laryngocarcinoma. METHOD: The NP, HN and F gene of the Newcastle disease virus were cloned into the pcDNA3 by RT-PCR. The human laryngeal squamous carcinoma model in nude mice had been established by transplantation of the Hep-2 cell line. The nude mice had been grouped two in the third week of the Hep-2 cell line had been transplanted. The admixture of the pcDNA3-NP and the pcDNA3-HN and pcDNA3-F were injected into the tumor in the experimental group, the equal weights pcDNA3 was injected into the tumor in the control group. The microstructural and ultra-micro-structural changes of carcinoma were observed under light and electron microscopes. The chromatosome DNA were extracted from all tissue of the nude mice, the DNA was tested to do template by PCR, whether or not exist the NP gene. The nude mice serums were examined by the method of enzyme-linked immunosorbent assay (ELISA) for the antigen of the DNA V4. RESULT: There were statistically significant difference in the mice weight, the tumor weight, the tumor volume and the restrained tumor rate between the experimental group and the control group (each P < 0.01). A nude mouse died in the control group, the others were very asthenic. The tumor looked like nodosity and the tumor surface were defeated. The tumor in the experimental group were smaller than that in the control group, the tumors were round shape and hard and not adhered on the skin and deep part constitution. The necrosis and apoptosis of the tumor cell had been found under light and electron microscopes. The NP gene had not been explored in all tumor tissue by PCR in the experimental group. The experimental group was positive in ELISA, The control group was negative. CONCLUSION: The NP, HN and F gene could play a role in treating tumor.

Animals↗