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Biomedical subjects

Jun Lu

Publications and source records attributed to Jun Lu.

At least 163 records · Page 9Linked to original sources
PubMed2003

[The treatment of benign prostatic hyperplasia by means of transurethral holmium laser enucleation].

OBJECTIVES: To evaluate the clinical effect of the holmium laser enucleation and morcellation of prostate (HoLEP) in the treatment of benign prostatic hyperplasia(BPH). METHODS: In the treatment of 35 BPH patients, 100 watt high-powered holmium laser set was used transurethrally and a reciprocating blade tissue morcellator was introduced via a nephroscope to enucleate and morcellate the prostatic tissue. RESULTS: Operations in all 35 cases were successful. The average operation time was 60 +/- 23.2 (range 30-180) min. The removed prostatic tissue weighed 31 +/- 9 (range 10-56) g on average. The average catheter time was 1.5 d (from 20 h to 4 d). No blood transfusion was performed in all cases. Histopathological analysis confirmed the diagnosis of BPH in all cases. In the 3-month follow up of 32 cases, IPSS dropped from 24 +/- 6.2 to 5.6 +/- 3.6; the peak urinary flow rate(Qmax) went up from 8.5 +/- 3.9 ml/s to 22.0 +/- 7.2 ml/s; the residual volume of urine dropped from 138 +/- 125 ml to 21 +/- 15 ml. No serious complications were found. CONCLUSIONS: HoLEP is effective in treating BPH. It can completely enucleate the hyperplastic tissue with little bleeding in operation. The treatment has the advantages of short catheter time and significant clinical improvements.

Aged↗
PubMed2003

[Effect of temperature on resistance of Pinus yunnanenensis to inoculation with Leptographium yunnanense, a pathogenic fungus associated with Tomicus piniperda].

The study showed that temperature had an important effect both on the resistance of Pinus yunnanensis and on the growth and virulence of Leptographium yunnanense, a pathogenic fungus associated with Tomicus piniperda attacking Pinus yunnanensis, which would result in the competence variation between them: at lower (< 10 degrees C) and higher temperature(> 30 degrees C), the growth and virulence of L. yunnanense were inhibited, while at 15 degrees C-30 degrees C, the resistance of Pinus yunnanensis was relatively weaker, indicating that in warmer climates, the growth and virulence of L. yunnanense were relatively strengthened, but the resistance of Pinus yunnanensis was relatively weakened.

Animals↗
PubMed2003

[The histone deacetylase activity of SIR2 and chromatin silencing].

Chromatin silencing is the inactivation of large domains of DNA by packaging them into a specialized inaccessible chromatin structure. This type of inactivation is involved in the regulation of gene expression and is also associated with the chromosome structures required for chromosome maintenance and inheritance. Silent information protein 2(SIR2) is one of the important proteins involved in chromatin silencing. It is clear that SIR2 has two coupled enzymatic activities, histone deacetylation and NAD breakdown activities, and produces a novel compound, O-acetyl-ADP-ribose in the enzymatic reactions. The histone deacetylation activity of SIR2 provides the direct link between SIR2 and the hypoacetylation of silent chromatin. Moreover, the relationship between the NAD cleavage and the deacetylase activity of SIR2 shows that the histone deacetylase activity is not its only crucial function. The breakdown of NAD C-N bond and the synthesis of O-acetyl-ADP-ribose may also be involved in chromatin silencing.

English Abstract↗
PubMed2003

[Cloning and prokaryotic expression of yeast GCN5 and RPD3].

The yeast histone acetyltransferase (HAT) gene gcn5 and histone deacetylase (HDAC) gene rpd3 were cloned from yeast genomic DNA by PCR amplification. The two genes,both with additional 6xHis tag,were subcloned into pBV220 vector to construct expression plasmids pBVgcn5 and pBVrpd3,respectively. Both pBVgcn5 and pBVrpd3 were over-expressed in Escherichia coli upon temperature induction,as revealed by SDS-PAGE. The recombinant GCN5 and RPD3 were purified by using a 6xHis affinity column. The purified GCN5 was tested to possess the HAT activity by using a (14)C-labeling assay. This work has laid down the basis for further in vitro studies into roles of histone acetylation/deacetylation in modulating chromatin conformation and transcription activity.

English Abstract↗
PubMed2002

Optimal design method of a low-loss broadband Y branch with a multimode waveguide section.

An optimal design method for a low broadband silica-on-silicon Y branc is considered. A multimode waveguide section, which was used earlier to reduce the excess loss, is designed optimally when the light distribution at the end of the multimode waveguide section is matched to the profile of the symmetric supermode for the structure of the two branching waveguides. An optimization method that combines the genetic algorithm and a gradient-based search method is used to obtain the optimal geometrical parameters for the multimode waveguide section as well as the widths for the input and branching waveguides.

Journal Article↗
PubMed2002

Histone acetylation is involved in hsp70 gene transcription regulation in Drosophila melanogaster.

The acetylation/deacetylation modifications of N-terminal tails of core histones play critical roles in activation/repression of many eukaryotic genes. However, the role of acetylation in transcription regulation of heat shock protein genes (hsp) is still a disputed issue. In this study, we investigated the influences of histone acetylation modification on changes in structure of polytene chromosomes and in expression of hsp70 gene in Drosophila melanogaster, by using histone deacetylase (HDAC) inhibitors Trichostatin A (TSA) and sodium butyrate (BuA), and the heat shock treatment of larvae of the flies. The results presented in this paper demonstrate that both TSA and BuA were able to affect the chromatin structure at the site where hsp70 gene is located along the polytene chromosome. Furthermore, the HDAC inhibitors significantly promoted the hsp70 gene transcription, at an extent similar to that induced by heat shock. The immunofluorescence in situ localization study further confirmed that the hsp70 gene locus was hyperacetylated after the heat induction. We therefore conclude that histone acetylation can significantly enhance both the basal and the inducible expression of hsp70 gene in D. melanogaster and hence plays important roles in hsp gene regulation. This study has provided a basis and a framework for further investigations aimed at the establishment of the correlation between acetylation modification and hsp gene regulation.

Acetylation↗
PubMed2002

Recognition of prostate tumor cells by cytotoxic T lymphocytes specific for prostate-specific membrane antigen.

The development of immunotherapy for cancer, such as synthetic peptide-based vaccines, relies heavily on the identification of appropriate epitopes capable of eliciting antitumor T-cell responses. We have used a combination of computer-based algorithms to predict peptide sequences from prostate-specific membrane antigen (PSMA) capable of stimulating in vitro CTLs restricted by the HLA-A2 MHC molecule. Four of the five peptides that were predicted by these algorithms were capable of inducing antigen-specific CTLs that killed target cells that were pulsed exogenously with the corresponding peptides. However, only one of the four peptides, PSMA(27), induced CTLs that were effective at recognizing prostate tumor cells expressing the HLA-A2 and PSMA molecules. These results underline the importance of demonstrating antitumor reactivity of peptide-induced CTLs for the selection of epitopes destined to become immunotherapeutic for prostate cancer.

Algorithms↗
PubMed2002

A selective effect of Mpl ligand on mRNA stabilization during megakaryocyte differentiation.

Megakaryocytes, the platelet precursors, are induced to differentiate in response to Mpl ligand. Here we report that stability of the megakaryocyte-specific platelet factor 4 (PF4) mRNA is substantially augmented in the presence of Mpl ligand. This stabilization requires protein synthesis, but the 3'-untranslated region of PF4 mRNA is not sufficient for granting the effect. This cytokine also significantly or mildly stabilizes Mpl receptor or GAPDH mRNAs, respectively, in contrast to a previously reported lack of effect on P2Y(1) receptor mRNA. Our study is the first to suggest that Mpl ligand-induced lineage specification is also determined by message stabilization.

3' Flanking Region↗
PubMed2002

[Different effects of acetylcholine on the action potential and force contraction in guinea pig atrial and ventricular myocardium].

The purpose of this study was to investigate the different effects of ACh on the action potential and force contraction in guinea pig atrial and ventricular myocardium by using standard microelectrodes and force transducer. The results showed that the duration of the action potential (APD) of atrial myocardium was shortened from 208.57+/-36.05 to 101.78+/-14.41 ms (n=6, P<0.01), and the APD of the ventricular myocardium was shortened from 286.73+/-36.11 to 265.16+/-30.06 ms (n=6, P<0.01).The amplitude of the action potential (APA) of the atrial myocardium was decreased from 88.00+/-9.35 to 62.62+/-20.50 mV (n=6, P<0.01), while the APA of the ventricular myocardium did not change significantly.The force contraction of atrial myocardium was inhibited completely (n=6, P<0.01), while the force contraction of ventricular myocardium was inhibited by 37.57+/-2.58% (n=6, P<0.01). The ACh effects correlated with its concentration. The K(D) of the APD shortening effects in the atrial and ventricular myocardium were 0.275 and 0.575 micromol/L. The K(D) of the negative inotropic in the atrial and ventricular myocardium were 0.135 and 0.676 micromol/L, respectively. The corresponding data points were compared using t test between the atrial and ventricular myocardium, and the differences were significant when the ACh concentration was above 10 nmol/L. Furthermore, atropine (10 micromol/L) and CsCl (20 mmol/L) blocked the effects of 10 micromol/L ACh on the APD of ventricular myocardium, while CdCl2 (0.1 mmol/L) had no influence on these effects. In conclusion, ACh could shorten the action potential duration and inhibit the force contraction of atrial and ventricular myocardium in a concentration-dependent manner. There are differences in the effects of ACh on the atrial and ventricular myocardium. The atrial myocardium is more sensitive to ACh than the ventricular myocardium. It is probable that the muscarinic receptor and the potassium channel, but not the calcium channel, are involved in the ACh-induced shortening of the ventricular APD.

Acetylcholine↗
PubMed2002

Octaphenylbiphenylene and dodecaphenyltriptycene.

Octaphenylbiphenylene, the expected dimer of tetraphenylbenzyne, has been prepared in low yield by diazotization of 3,4,5,6-tetraphenylanthranilic acid, and its X-ray structure has been determined. The X-ray structure of a second, abnormal dimer of tetraphenylbenzyne, 1,2,3,8,9,10-hexaphenyldibenzo[fg,op]naphthacene has also been determined; this is a saddle-shaped polycyclic aromatic hydrocarbon. 1,2,3,4,5,6,7,8,13,14,15,16-Dodecaphenyltriptycene, perhaps the most crowded triptycene derivative yet prepared, has been made by the reaction of tetraphenylbenzyne with 1,2,3,4,5,6,7,8-octaphenylanthracene, which in turn was synthesized in two steps from commercial starting materials. The X-ray structure of the dodecaphenyltriptycene nonabenzene solvate is a remarkable channel containing structure in which more than 50% of the unit cell volume is occupied by the benzene molecules.

Journal Article↗
PubMed2002

Tumor-associated B7-H1 promotes T-cell apoptosis: a potential mechanism of immune evasion.

B7-H1, a recently described member of the B7 family of costimulatory molecules, is thought to be involved in the regulation of cellular and humoral immune responses through the PD-1 receptor on activated T and B cells. We report here that, except for cells of the macrophage lineage, normal human tissues do not express B7-H1. In contrast, B7-H1 is abundant in human carcinomas of lung, ovary and colon and in melanomas. The pro-inflammatory cytokine interferon-gamma upregulates B7-H1 on the surface of tumor cell lines. Cancer cell-associated B7-H1 increases apoptosis of antigen-specific human T-cell clones in vitro, and the apoptotic effect of B7-H1 is mediated largely by one or more receptors other than PD-1. In addition, expression of B7-H1 on mouse P815 tumor increases apoptosis of activated tumor-reactive T cells and promotes the growth of highly immunogenic B7-1(+) tumors in vivo. These findings have implications for the design of T cell-based cancer immunotherapy.

Animals↗
PubMed2002

Selective activation of the extended ventrolateral preoptic nucleus during rapid eye movement sleep.

We found previously that damage to a cluster of sleep-active neurons (Fos-positive during sleep) in the ventrolateral preoptic nucleus (VLPO) decreases non-rapid eye movement (NREM) sleep in rats, whereas injury to the sleep-active cells extending dorsally and medially from the VLPO cluster (the extended VLPO) diminishes REM sleep. These results led us to examine whether neurons in the extended VLPO are activated during REM sleep and the connectivity of these neurons with pontine sites implicated in producing REM sleep: the laterodorsal tegmental nucleus (LDT), dorsal raphe nucleus (DRN), and locus ceruleus (LC). After periods of dark exposure that triggered enrichment of REM sleep, the number of Fos-positive cells in the extended VLPO was highly correlated with REM but not NREM sleep. In contrast, the number of Fos-positive cells in the VLPO cluster was correlated with NREM but not REM sleep. Sixty percent of sleep-active cells in the extended VLPO and 90% of sleep-active cells in the VLPO cluster in dark-treated animals contained galanin mRNA. Retrograde tracing from the LDT, DRN, and LC demonstrated more labeled cells in the extended VLPO than the VLPO cluster, and 50% of these in the extended VLPO were sleep-active. Anterograde tracing showed that projections from the extended VLPO and VLPO cluster targeted the cell bodies and dendrites of DRN serotoninergic neurons and LC noradrenergic neurons but were not apposed to cholinergic neurons in the LDT. The connections and physiological activity of the extended VLPO suggest a specialized role in the regulation of REM sleep.

Animals↗
PubMed2002

Solution structure of the Vam7p PX domain.

PX domains have been recently found to act as phosphoinositide binding modules. In the yeast SNARE protein Vam7p, the PX domain binds to PtdIns(3)P and is required for vacuolar targeting. To gain insight into how PX domains function, the solution structure of the ligand-free Vam7p PX domain has been determined by NMR spectroscopy. The Vam7p PX domain has the same overall alpha/beta fold observed in the structures of the ligand-free p47(phox) PX domain and the PtdIns(3)P-bound p40(phox) PX domain, exhibiting several similarities and differences with these two PX domains. Most striking is the similarity between the Vam7p and p40(phox) PX domains in a subset of secondary structure elements despite the low level of sequence identity between them, suggesting that these elements form a conserved core in the PX domain fold. These similarities and the observation that a putative PtdIns(3)P binding site is already formed in the apo Vam7p PX domains suggest that ligand binding does not induce major conformational changes, contrary to what was previously thought. The proposed ligand binding site of the Vam7p PX domain includes basic side chains from the conserved structural core that also participate in PtdIns(3)P binding to the p40(phox) PX domain, and basic side chains from a variable loop that probably inserts into the membrane. These results indicate that PX domains contain a combination of conserved and variable features that allow them to have a common function and at the same time exhibit distinct specificities, mechanisms of regulation, or modes of interaction with effector molecules.

Amino Acid Sequence↗
PubMed2002

Mild benzene-thermal route to GaP nanorods and nanospheres.

GaP nanorods and nanospheres were synthesized from a mild benzene-thermal route at 240 and 300 degrees C, respectively, using Na, P, and GaCl(3) as the starting materials. The structure of the products was identified as zinc blende phase by X-ray powder diffraction (XRD). Transmission electron microscopy (TEM) images showed that, when the reaction temperature was 240 degrees C, the products were nanorods with widths of 20-40 nm and lengths of 200-500 nm and nanospheres with diameters of 20-40 nm. However, when the reaction temperature was increased to 300 degrees C, the products were only nanospheres, and the diameters increased to 40-60 nm. The reaction proceeded through a metallic gallium intermediate, and a solution-liquid-solid (SLS) mechanism was proposed for the one-dimensional growth. The products were also investigated by UV-vis absorption and X-ray photoelectron spectroscopy.

Journal Article↗
PubMed2002

Strategies for antigen loading of dendritic cells to enhance the antitumor immune response.

Dendritic cells (DCs) primed with tumor antigens can effectively mediate the regression of a variety of established solid malignancies in both murine and human models. Despite such clinical efficacy, the optimal means of DC priming is unknown. The goal of this study was to compare three methods of tumor preparation: irradiation, boiling, or freeze thaw lysis for DC priming. Mouse bone marrow-derived DCs were loaded with defined ratios of E.G7 tumor cells expressing a model tumor antigen, OVA. Sensitized DCs were used for stimulation of OVA-specific CTLs derived from OT-1 T-cell receptor transgenic mice. IFN-gamma release, determined by ELISA at 24 and 48 h, was used to assess the expression of antigens by DCs. DCs loaded with irradiated tumors were effective stimulators for OT-1 CTLs, whereas DCs stimulated with freeze-thawed or boiled tumors did not stimulate IFN-gamma production. Freeze-thaw lysis appeared to inhibit CTL activity in vitro and in two of three cases, this effect was not overcome by the addition of OVA. The ability to load irradiated tumor cells was reproduced in two analogous human melanoma models using melanoma cell lines expressing gp100 and CTL clones specific for a gp100 melanoma antigen. Consistent with the in vitro data, only DC/irradiated tumor vaccines were effective in preventing or delaying outgrowth of E.G7 and a poorly immunogenic murine squamous cell carcinoma (SCCVII), on local tumor challenge. These data demonstrate that the method of tumor cell preparation clearly influences the ability of DCs to present antigen to T cells. Correlation of in vitro data with the generation of protective immunity in vivo suggests the utility of irradiated tumor-primed DCs as a means to generate protective immunity in patients with solid malignancies.

Animals↗
PubMed2002

The basic helix-loop-helix domain of the E47 transcription factor requires other protein regions for full DNA binding activity.

Most transcription factors are believed to be composed of independently functioning modules [A. D. Frankel and P. S. Kim (1991) Cell 65, 717-719]. Basic helix-loop-helix (bHLH) transcription factors appear to fit this model, with the HLH domains mediating dimerization, the basic regions mediating DNA binding, and other modules controlling other functions such as transcriptional activation. We tested predictions of this model using forced dimers of bHLH proteins including E47 homodimers and MyoD:E47 heterodimers and found that protein dimers containing complete bHLH domains but lacking other regions of E47 have only 20% of the DNA binding ability and transcriptional transactivation activity of wild-type dimers. These results demonstrate that the bHLH domains do not function as completely independent DNA binding modules. In addition, these results demonstrate that the transcriptional activation domains from a single bHLH protein are sufficient to activate transcription.

3T3 Cells↗