An instrument for measuring scintillators efficiently based on silicon photomultipliers

An instrument used for measuring multiple scintillators' light output and energy resolution was developed. The instrument consisted of a light sensor array which was composed of 64 discrete SiPMs (Silicon Photomultipliers), a corresponding individual channel readout electronics system, and a data processing algorithm. A Teflon grid and a large interval between adjacent SiPMs were employed to eliminate the optical cross talk among scintillators. The scintillators' light output was obtained by comparing with a reference sample with known light output. Given the SiPM temperature dependency and the difference among each SiPM, a temperature offset correction algorithm and a non-uniformity correction algorithm were added to the instrument. A positioning algorithm, based on nine points, was designed to evaluate the performance of a scintillator array. Tests were performed to evaluate the instrument's performance. The uniformity of 64 channels for light output measurement was better than 98%, the stability was better than 98% when temperature varied from 15 °C to 40 °C, and the nonlinearity under 511 keV was better than 2%. This instrument was capable of selecting scintillators and evaluating the packaging technology of scintillator arrays with high efficiency and accuracy.

Abstract 4929: UbcH10 may represent a potential marker of gastric carcinoma

Gastric cancer is a fatal disease with limited early diagnostic methods available. There is an urgent need to find more effective targets for early diagnosis and therapeutics. UbcH10 is an ubiquitin-conjugating enzyme with a high expression reported in some cancers. Several gastric tumor cell lines with high or low expression of UbcH10 were exploited to study the role of UbcH10 in gastric cancer. Knocking down of UbcH10 expression using siRNA in high expressing gastric cancer cell lines resulted in reduced proliferation, increased cisplatin-induced apoptosis and reduced serum-induced ERK, Akt and p38 phosphorylation signaling. In agreement, overexpression of UbcH10 expression in low-expression gastric cancer cell lines led to enhanced cell proliferation, resistance to cisplatin-induced apoptosis. Most importantly, IHC analyses showed that the UbcH10 protein expressed at a high level in patient gastric cancer tissues, but not in adjacent mesenchyme tissues. These data suggest that UbcH10 may promote gastric cancer growth and can serve as a biomarker for diagnosis or target for new therapeutics in gastric cancer.

Citation Format: Mengxuan Yang, Yingying Qu, Gang Hu, Shiwei Tu, RL Shi, XB Wu, ZQ Hu, QM Zhang, SQ Liu, GF Pan, Ziping Zhang, He Zhou. UbcH10 may represent a potential marker of gastric carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4929.

Rapamycin, a specific inhibitor of the target of rapamycin complex 1, disrupts intestinal barrier integrity in broiler chicks

To uncover the molecular mechanisms underlying the intestinal barrier integrity, this study determined whether the rapamycin (RAPA)-sensitive target of rapamycin complex 1 (TORC1) pathway was involved in this process. Three groups of 4-day-old male chicks were randomly subjected to one of the following treatments for 6 days: high-dose RAPA [a specific inhibitor of TORC1; an intraperitoneal injection of 1.0 mg/kg body weight (BW), once daily at 09:00 hours], low-dose RAPA (0.4 mg/kg BW) and RAPA vehicle (control). Results showed that the RAPA treatment increased mortality, while decreasing villus height (p < 0.01), claudin 1 expression, content of immunoglobulin A (IgA), extent of TORC1 phosphorylation (p < 0.05), ratio of villus height to crypt depth (p < 0.01), and population of IgA-positive B cells in intestinal mucosa, particularly for the jejunum. Some aspects of these responses were dose dependent and appeared to result from weight loss. Together, RAPA exerts the expected inhibition of small intestinal development and IgA production in birds, suggesting the important role of TORC1 in gut barrier integrity.

Correlation of serum high-sensitivity C-reactive protein and interleukin-6 in patients with acute coronary syndrome

Serum high-sensitivity C-reactive protein (hs-CRP) is a sensitive indicator of inflammation, which is closely related with the progress of plaque formation. Interleukin-6 (IL-6) is one of the inflammatory markers of local coronary plaque and the peripheral blood cycle, promoting the occurrence of atherosclerosis development and plaque rupture. In this study, the correlation of hs-CRP and IL-6 was investigated in patients with acute coronary syndrome (ACS). Sixty cases of ACS, including 33 cases of acute myocardial infarction (AMI) and 27 cases of unstable angina pectoris (UAP), 45 cases of stable angina pectoris (SAP), and 45 healthy people (HG) were enrolled in study. The serum hs-CRP and serum IL-6 levels were tested by the immune turbidimetric method and enzyme-linked immunosorbent assay (ELISA), respectively. The differences among groups and their correlations were evaluated. Results showed that the serum hs-CRP and IL-6 concentrations of the AMI and UAP groups were significantly higher than those of the SAP and HG groups, respectively (P<0.01), and those of the AMI group were significantly higher than those of the UAP group (P<0.05). The serum hs-CRP and IL-6 levels of the ACS group were positively correlated (r=0.836). The serum hs-CRP and IL-6 levels could be used to determine the stability of plaque, and have some relevance in the ACS process, showing great value in judgments of ACS prognosis.

Dillapiol: a pyrethrum synergist for control of the Colorado potato beetle

Dillapiol, the main constituent in dill Anethum sowa Roxb. ex Fleming (Apiaceae) oil and wild pepper, Piper aduncum L. (Piperaceae), is an effective cytochrome P450 inhibitor similar to piperonylbutoxide (PBO). Laboratory and field trials with pyrethrum Chrysanthemum cinerariifolium (Trevir.) vis. extracts combined with dillapiol (1:5 and 1:16 ratio) were effective against both insecticide-susceptible and -resistant Colorado potato beetle Leptinotarsa decemlineata (Say). In the laboratory, pyrethrum efficacy was increased 2.2-fold with the SS strain and 9.1-fold with the RS strains by using pyrethrum + dillapiol. Two field trials with the pyrethrum + dillapiol formulation demonstrated efficacy > or = 10 times than that of pyrethrum alone. The residual activity (half-life) of the combination exposed to direct sunlight was 3 h but it increased to 10.7 h by adding 2% of the sunscreen octylmethoxycinnamate.

Genome-wide analysis of the auxin response factor gene family in cucumber

Auxin response factors (ARFs) participate in the transcriptional regulation of a series of biological processes related to growth and development. The ARF genes comprise a large multigene family in plants. Recently, a draft of the full cucumber (Cucumis sativus) genome assembly has been released; however, none of the ARF genes have been characterized. We made a comprehensive analysis of ARF genes in this species. Fifteen ARF genes were identified and could be divided into three classes. Intron presence and position were conserved to some extent within one phylogenetic group. Based on genome distribution analysis, tandem duplication appears to have contributed to ARF gene expansion. Specific motifs were selectively distributed among specific clades. Putative cis-elements involved in auxin response, light signaling responses, phytohormones, and defense responses were identified in promoter regions of the ARF genes. Almost all of the ARF genes exhibited a constitutive expression pattern, implying that there are functional redundancies among the ARF proteins.

Colorimetric detection of DNA damage by using hemin-graphene nanocomposites

A colorimetric method for detection of DNA damage was developed by using hemin-graphene nanosheets (H-GNs). H-GNs were skillfully synthesized by adsorping of hemin on graphene through π-π interactions. The as-prepared H-GNs possessed both the ability of graphene to differentiate the damage DNA from intact DNA and the catalytic action of hemin. The damaged DNA made H-GNs coagulated to different degrees from the intact DNA because there were different amount of negative charge exposed on their surface, which made a great impact on the solubility of H-GNs. As a result, the corresponding centrifugal supernatant of H-GNs solution showed different color in the presence of 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2, which could be discriminated by naked eyes or by ultraviolet (UV)-visible spectrometer. Based on this, the damaged effects of styrene oxide (SO), NaAsO2 and UV radiation on DNA were studied. Results showed that SO exerted most serious damage effect on DNA although all of them damaged DNA seriously. The new method for detection of DNA damage showed good prospect in the evaluation of genotoxicity of new compounds, the maximum limit of pesticide residue, food additives, and so on, which is important in the fields of food science, pharmaceutical science and pesticide science.

Electrochemiluminescent detection of mucin 1 protein and MCF-7 cancer cells based on the resonance energy transfer

A novel sensing strategy for sensitive detection of mucin 1 protein (MUC1) and MCF-7 cells based on electrochemiluminescence (ECL) resonance energy transfer (ERET) from bis(2,2'-bipyridine)-(5-aminophenanthroline)ruthenium(II) (Ru1) to graphene oxide (GO) was proposed. The MUC1 aptamer was covalently combined with Ru1 (Ru1-aptamer) using aqueous carbodiimide coupling chemistry. Due to the strong noncovalent interaction between the Ru1-aptamer and GO, the ECL of Ru1 was efficiently quenched because of the ERET. In the presence of a target MUC1 protein, the binding between the Ru1-aptamer and MUC1 disturbed the interaction between the Ru1-aptamer and GO. These interactions led to the release of the Ru1-aptamer from GO, and resulted in the restoration of Ru1 ECL. This was shown to detect MUC1 protein sensitively in a linear range from 64.9 to 1036.8 nM with a detection limit of 40 nM. With further application in the detection of MCF-7 cells, the presented method could respond at concentrations as low as 30 cancer cells per mL. By substituting the aptamer and the corresponding target, this method could be conveniently extended for the sensitive detection of other biomolecules.

Assessment of the number of local cytotoxic T lymphocytes required for degradation of micrometer-size tumor spheroids

Adoptive immunotherapy with human cytotoxic T lymphocytes (CTL) is a promising cancer treatment. Previously we showed that human CTLs against various types of tumors can be efficiently produced by coculturing peripheral blood cells with target cells. The aims of this study were to simulate the interaction of CTLs and micrometer-size tumor tissues in vitro and to assess the required number of CTLs at local tumor sites for degradation of a tumor. Allogeneic CTLs against a human transitional cell carcinoma cell line and autologous CTLs against a renal cell carcinoma cell derived from a surgical specimen were generated. The cytotoxic activities of CTLs against tumor cells in monolayer culture and tumor spheroids formed in U-bottom 96-well culture plates were assessed. Both allogeneic and autologous CTLs showed greater destructive activity than lymphokine activated killer (LAK) cells against target tumor spheroids. CTLs inoculated at E/T ratios of 0.1 to 1 coexisted with the tumor spheroid for 5 to 6 days and then increased in number with apparently lethal activity against the tumor spheroid. In contrast to CTLs, the increase in LAK cell numbers was scarcely observed, and the proliferated LAK cells did not show cytotoxicity against the tumor spheroid. These observations suggest that, when a small number of CTLs reach a local tumor site, they can destroy micrometer-size tumors after considerable local proliferation.

IL-17RA aptamer-mediated repression of IL-6 inhibits synovium inflammation in a murine model of osteoarthritis

OBJECTIVE

Generate DNA aptamers to inhibit IL-17RA-mediated synovial inflammation in an experimental mouse model of osteoarthritis (OA).

METHODS

A novel cell-SELEX method was applied to obtain DNA aptamers specific for IL-17RA. A single-stranded (ss) DNA library with four(30) probes was synthesised. By incubating this library with NIH3T3 cells, we collected DNA ligands that could bind the cell surface. The collected ligands were incubated with IL-17RA-deficient NIH3T3 cells, and unbound ssDNA was harvested from the supernatant for the next round of selection. After 12 cycles, specific aptamers against IL-17RA were generated. For animal experiments, a meniscectomy was performed on Balb/C mice to generate an animal model of OA. Mice received weekly intra-articular (i.a.) injections of aptamers or control treatments for 6 weeks. Synovial membranes were evaluated by histomorphology and the mRNAs of critical inflammatory cytokines were measured by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

An aptamer termed RA10-6 was obtained that could efficiently block IL-17 binding to IL-17RA in a dose-dependent manner in vitro. Histological examination and quantitative RT-PCR results showed that OA mice that injected with RA10-6, especially in combination with celecoxib demonstrated inhibition of synovial thickening and reduction in IL-6 levels in the synovial tissue.

CONCLUSION

Our results suggest that RA10-6 can inhibit synovial inflammation by blocking IL-17/IL-17RA-mediated IL-6 expression. RA10-6 acted synergistically with celecoxib to inhibit IL-6 expression in synovial tissues. Thus, aptamers targeting IL-17RA might serve as potent adjunctive agents for the early treatment of OA.

Enhanced radiosensitivity of SW480 cells via TRAIL up-regulation mediated by Egr-1 promoter

Radiosensitization of cancer cells to irradiation could improve the efficacy of radiotherapy. The early transcriptional factor (Egr-1) promoter induced expression of downstream genes after irradiation. TNF-related apoptosis-inducing ligand (TRAIL) is known to induce apoptosis in malignant cells, but displayed little or no toxicity on normal cells. In this study, we constructed pcDNA3.1-Egr-1-TRAIL (pEgr.1-TRAIL) recombinant plasmid and evaluated its effect on human colon cancer cell line SW480. pEgr.1-TRAIL transfection combined with radiotherapy caused dramatically elevation of TRAIL expression both in mRNA and protein levels, much lower radiobiological parameters in clonogenic assays, accompanied by remarkably increase in apoptosis ratio. Furthermore, pEgr.1-TRAIL transfected cells displayed higher proportion in G0/G1 phase. Our results suggested that pEgr.1-TRAIL can sensitize SW480 cells to radiation, and the radiosensitization is related to cell cycle changes and apoptosis mediated by up-regulation of TRAIL expression. These findings support the potential future application of genetic radiotherapy against carcinoma.

Cytotoxicity and radiosensitization effect of TRA-8 on radioresistant human larynx squamous carcinoma cells

TRAIL induces apoptosis in a variety of tumorigenic and transformed cell lines, but not in many normal cells. Recent studies have demonstrated that death receptor 5 (DR5), one of the two death receptors bound by TRAIL, showed expression in most malignantly transformed cells. This study evaluated effects of a monoclonal antibody (TRA-8) to human death receptor 5, combined with ionizing radiation, on radioresistant human larynx squamous carcinoma cell line (Hep-2R). Cells were treated with TRA-8 alone or in combination with radiation, cell viability inhibition was measured by MTT assay, and the induction of apoptosis was determined by Annexin V staining. Radionsensitivity of Hep-2R cells treated with TRA-8 were investigated with long-term clonogenic assays. Regulation of DR5 expression in cells after radiation was analyzed by indirect immunofluorescence using murine TRA-8 in combination with flow cytometry. The results suggested that TRA-8 enhanced radionsensitivity of Hep-2R cells, and that TRA-8 regulated Hep-2R cell cycle arrest at G2/M phase. Irradiation up-regulated the expression of DR5, and when combined with TRA-8 yielded optimal survival benefit. Therefore, TRA-8 can be used in combination with irradiation in radioresistant human larynx squamous carcinoma cells. Monoclonal antibodies such as TRA-8 may play an important role in the development of an effective treatment strategy for patients with radioresistant cancers.

A PstI polymorphism at 3'UTR of goat POU1F1 gene and its effect on cashmere production

POU1F1 is a positive regulator for prolactin (PRL) whose metabolites may directly or indirectly affect some aspects of the hair growth cycle, therefore, POU1F1 gene is an important candidate gene for cashmere traits selection through marker-assisted selection (MAS). Hence, in this study, the PCR-RFLP method was applied to detect a T>C transition determining a PstI polymorphism at the 3'UTR of POU1F1 locus and evaluate its associations with cashmere traits in 847 Inner Mongolia White Cashmere goats. In the analyzed population, the allelic frequencies for the T and C alleles are 0.959 and 0.041, respectively and the genotypic frequencies are in Hardy-Weinberg equilibrium (P > 0.05). Moreover, significant statistical relationships between the PstI polymorphism of POU1F1 gene and goat cashmere yields were found (*P < 0.05). When compared with TC genotype, TT genotype was associated with superior cashmere yields in 2, 4, and 5 years old individuals, as well as with average cashmere yield. Hence, TT genotype is suggested to be a molecular marker for senior cashmere yield.

Acaricidal activity of Juglans regia leaf extracts on Tetranychus viennensis and Tetranychus cinnabarinus (Acari: Tetranychidae)

Leaf extracts of the walnut, Juglans regia L., were evaluated under laboratory conditions to determine their acaricidal activity on the mites Tetranychus cinnabarinus (Boisduval) and Tetranychus viennensis Zacher (Acari: Tetranychidae). Extracts had both contact and systemic toxicity to these mites. The four solvents tested for preparing crude extracts were petroleum ether, chloroform, ethyl acetate, and methanol. Methanol was the most efficient solvent, with an extraction rate from 17.06 + 0.80 to 20.27 +/- 0.28%. Petroleum ether was the least effective solvent, with extraction rates from 2.30 +/- 0.13 to 2.71 +/- 0.13%. However, the crude extracts with petroleum ether resulted in the highest mite mortality (79.04 +/- 0.52%) in a slide dip bioassay. Mites mortalities from the concentrated extracts prepared by chloroform, ethyl acetate, methanol, or distilled water were significantly lower than petroleum ether. The mean lethal concentrations (LC50) of the extracts from petroleum ether, chloroform, ethyl acetate, methanol, and distilled water to the two mite species were 0.73 +/- 0.04, 1.66 +/- 0.28, 4.96 +/- 0.35, 7.45 +/- 0.67, and 9.91 +/- 0.32 mg/ml, respectively. After liquid chromatography and thin-layer chromatography, the concentrated extracts of petroleum ether were separated into eight fractions and tested for acaricidal activity. Fraction 6 produced significantly higher mite mortality rates than the other groups, killing approximately 90% of both species.

Acaricidal activities of extracts of Kochia scoparia against Tetranychus urticae, Tetranychus cinnabarinus, and Tetranychus viennensis (Acari: Tetranychidae)

Extracts of an annual herbaceous plant, Kochia scoparia (L.) Schrad (Macrophomina), were bioassayed to determine their acaricidal activities against Tetranychus urticae Koch, Tetranychus cinnabarinus (Boisduval), and Tetranychus viennensis Zacher (Acari: Tetranychidae) in the laboratory. Extracts had both contact and systemic toxicity to these mites. Three solvents were tested for preparing crude extracts: petroleum ether, chloroform, and methanol. Methanol was the most effective solvent, extracting 3.11-4.53% of the acaricide. Petroleum ether was the least effective solvent, extracting 1.25-1.54%. However, extracts with chloroform resulted in the highest mite mortality (78.86%), and ultrasound-assisted extraction required the least time (10 min). Concentrated extracts were prepared using chloroform, methyl acetate, or distilled water as a solvent. Mite mortalities from the concentrated extracts by methyl acetate or distilled water were significantly lower than those by chloroform. The mean lethal concentrations (LC50) of the extracts by chloroform, methyl acetate, and distilled water to the mites were 0.71 +/- 0.06, 2.08 +/- 0.16 and 8.75 +/- 0.062 mg/ml, respectively. After liquid chromatography and thin layer chromatography, the concentrated extracts by chloroform were separated into seven groups of isolated fractions and tested for acaricidal activity.

Microwave tumour coagulation plus in situ treatment with cytokine-microparticles: induction of potent anti-residual tumour immunity

After local microwave coagulation and subsequent intra-tumoural injection of microparticles encapsulating interleukin-2 and granulocyte-macrophage colony-stimulating factor, the anti-tumour efficacy against subcutaneous Lewis lung carcinoma in syngeneic mice was evaluated. This treatment elicited a potent systemic anti-tumour immunity that protected treated mice from re-challenge with the same tumour cells and caused the distal tumours in a bilateral tumour model to be rejected. Cytotoxicity assay indicated that both T- and natural killer cells acted as the effector cells in the anti-tumour immunity. These data highlight the feasibility of microwave-pre-treated in situ cancer vaccination for clinical use.

Incorporation and in vitro release of doxorubicin in thermally sensitive micelles made from poly(-isopropylacrylamide---dimethylacrylamide)--poly(,-lactide--glycolide) with varying compositions

Thermally sensitive block copolymers, poly(N-isopropylacrylamide-co-N, N-dimethylacrylamide)-b-poly(d,l-lactide-co-glycolide) [P(NIPAAm-co-DMAAm)-b-poly(D,L-lactide-co-glycolide) (PLGA)] with different compositions and lengths of PLGA block are synthesized and utilized to fabricate micelles containing doxorubicin (DOX), a model anticancer drug, by a membrane dialysis method for targeted anticancer drug delivery. The critical association concentration (CAC) of the polymers ranges from 4.0 to 25.0 mg/L. An increased length of core-forming block PLGA leads to a decrease in the CAC. The clearly defined core-shell structure of micelles is proved by 1H-NMR analyses of the micelles in CDCl3 and D2O. The morphology of the micelles is analyzed by transmission electron microscopy, showing a spherical structure of both blank and drug-loaded micelles. The results obtained from dynamic light scattering show that the blank and drug-loaded micelles have an average size below 200 nm. The lower critical solution temperature (LCST) of the micelles made from the various polymers is similar, around 39 degrees C in phophate-buffered solution (PBS). The presence of serum in PBS does not alter the LCST significantly. The drug loading capacity varies depending on the PLGA block. The polymers are degradable, and the degradation of PLGA-based polymers is faster than that of poly(lactide) (PLA)-based polymer. The DOX-loaded micelles are stable in PBS containing serum at 37 degrees C but deform at 39.5 degrees C above the normal body temperature, thus triggering DOX release. It is revealed by confocal laser scanning microscopy that free DOX molecules enter cell nuclei very fast and DOX-loaded micelles accumulate mostly in cytoplasm after endocytosis. At a temperature above the LCST, more DOX molecules release from the micelles and enter the nuclei as compared to the temperature below the LCST. DOX-loaded micelles show greater cytotoxicity at a temperature above the LCST. The P(NIPAAm-co-DMAAm)-b-PLGA micelles developed may be a good carrier for anticancer drug delivery.

Thermally sensitive micelles self-assembled from poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide)-b-poly(D,L-lactide-co-glycolide) for controlled delivery of paclitaxel

Thermally sensitive micelles self-assembled from poly(N-isopropylacrylamide-co- N,N-dimethylacrylamide)-b-poly(d,l-lactide-co-glycolide)[P(NIPAAm-co-DMAAm)-b-PLGA] are fabricated and used as a carrier for the controlled delivery of paclitaxel. Paclitaxel is efficiently loaded into the micelles by a membrane dialysis method. The lower critical solution temperature (LCST) of the micelles is 39.0 degrees C in PBS. Encapsulation efficiency and loading level of paclitaxel are affected by the initial loading level of paclitaxel, fabrication temperature and polymer composition. The blank and paclitaxel-loaded micelles are characterized by particle size analysis (DLS), morphology (TEM and AFM) and paclitaxel distribution (NMR, DSC and WAXRD). The micelles are spherical in shape, having an average size less than 130 nm. Paclitaxel is molecularly distributed within the core of micelles. Sustained release of paclitaxel is achieved, which is much faster at a temperature above the LCST than at the normal body temperature (37 degrees C). Cytotoxicity of free paclitaxel and paclitaxel-loaded micelles against a human breast carcinoma cell line (MDA-MB-435S) is studied at different temperatures. The cytotoxicity of the paclitaxol-loaded micelles is greater as compared to free paclitaxel. Enhanced cytotoxicity is achieved by the paclitaxol-loaded micelles when the environmental temperature increases slightly above the LCST. Paclitaxel-loaded P(NIPAAm-co-DMAAm)-b-PLGA micelles may provide a good formulation for cancer therapy.

Acaricidal activities of extracts of Stellera chamaejasme against Tetranychus viennensis (Acari: Tetranychidae)

Extracts of a perennial and poisonous weed, Stellera chamaejasme L. (Thymelaeaceae) were bioassayed to determine their acaricidal activities against Tetranychus viennensis Zacher (Acari: Tetranychidae) in the laboratory. Extracts had both contact and systemic toxicity to the mite. After liquid chromatography and thin layer chromatography, the extract was further concentrated, separated, and bioassayed. This study is the first to report the acaricidal property of S. chamaejasme and its potential as a botanical pest control agent.

A possible role of initial cell death due to mechanical stretch in the regulation of subsequent cell proliferation in experimental vein grafts

The proliferation of vascular cells contributes to the formation of neointima and hypertrophy of the blood vessel wall. Here we show that mechanical stretch possibly regulates the proliferation of vascular cells via the mediation of cell death in a rat vein graft model. The wall of vein grafts is subject to a suddenly increased mechanical stretch due to exposure to arterial blood pressure. Such a stretch induces rapid cell death with a reduction in cell density by approximately 60% within the first day after surgery. The initial cell death was followed by an increase in the percentage of proliferating cells, as shown by a BrdU incorporation assay (1.55 +/- 1.27%, 8.48 +/- 2.27%, 11.93 +/- 2.36%, 6.36 +/- 1.77%, and 5.60 +/- 1.46% at days 1, 5, 10, 20, and 30, respectively). When mechanical stretch was reduced by restraining the vein graft using a polytetrafluoroethylene sheath, the percentage of proliferating cells reduced significantly (0.76 +/- 0.76%, 1.70 +/- 0.46%, 1.29 +/- 0.56%, 0.99 +/- 0.83%, and 0.47+/-0.52% at days 1, 5, 10, 20, and 30, respectively). A further reduction in cell density, induced by local administration of a cell death inducer ceramide to experimental vein grafts (without sheath), enhanced subsequent cell proliferation. In contrast, a prevention of cell death, induced by local administration of a cell death inhibitor tetrapeptide-aldehyde DEVD-CHO to experimental vein grafts (without sheath), significantly reduced subsequent cell proliferation. These results suggest that mechanical stretch induces cell death, which possibly mediates subsequent cell proliferation in the present model.

[Inhibition of telomerase activity by ribozyme targeted to human telomerase transcriptase]

Human telomerase reverse transcriptase (hTERT) is the catalytic subunit and the key factor which controls the telomerase activity,so it is the best choice to inhibit telomerase through controling hTERT expression.In this work,a hammer head ribozyme directed against the hTERT mRNA (hTERTRZ) was designed and synthesized to serve as a telomerase inhibitor. In order to test its in vitro cleavage activity, two in vitro transcription plasmids containing hTERTRZ and hTERT gene respectively were constructed. Ribozyme RNA and DIG-labeled-hTERT were synthesized by in vitro transcription. In vitro cleavage reactions were carried out by mixing the hTERTRZ with DIG-labeled-hTERT under different reaction conditions, and cleavage bands were detected by digoxin chemiluminescent assay. hTERTRZ showed a specific cleavage activity against the hTERT used as template. To investigate its in vivo effect of telomerase inhibition in tumor cells, a eukaryotic expression plasmid containing the hTERT ribozyme gene was introduced into HeLa cells and hepatoma cells by using LipofectAMINE. In the transfectants, the level of intact hTERT mRNA and the telomerase activity were clearly reduced, and the telomere length of these clones was apparently shortened at the beginning period, then kept a fixed value without further shortening. All the transfectants with ribozyme grew clearly more slowly than the parental cell line. The doubling time of the tansfectants prolonged compared to the negative control, but no apparent apoptosis was shown even at their 37th passage. These findings suggest the potential application of this ribozyme as a new theraputic agent directed against immortalized cancer cells.

Control of the shape of a thrombus-neointima-like structure by blood shear stress

Fluid mechanical factors are thought to influence vascular morphogenesis. Here we show how blood shear stress regulates the shape of a thrombus-neointima-like tissue on a polymer micro-cylinder implanted in the center of the rat vena cava with the micro-cylinder perpendicular to blood flow. In this model, the micro-cylinder is exposed to a laminarflow with a known shear stress field in the leading region and a vortexflow in the trailing region. At 1, 5, 10, 20, and 30 days after implantation, it was found that the micro-cylinder was encapsulated by a thrombus-neointima-like tissue with a streamlined body profile. The highest growth rate of the thrombus-neointima-like tissue was found along the trailing and leading stagnation edges of the micro-cylinder. Blood shear stress in the laminar flow region was inversely correlated with the rate of thrombus formation and cell proliferation, and the percentage of smooth muscle a actin-positive cells. These biological changes were also found in the trailing vortex flow region, which was associated with lowered shear stress. These results suggest that blood shear stress regulates the rate of thrombus and neointimal formation and, thus, influences the shape of the thrombus-neointima-like structure in the present model.

Identification of biochemical pathways for the metabolism of oxidized low-density lipoprotein derived aldehyde-4-hydroxy trans-2-nonenal in vascular smooth muscle cells

Oxidation of low-density lipoproteins (LDL) generates high concentrations of unsaturated aldehydes, such as 4-hydroxy trans-2-nonenal (HNE). These aldehydes are mitogenic to vascular smooth muscle cells and sustain a vascular inflammation. Nevertheless, the processes that mediate and regulate the vascular metabolism of these aldehydes have not been examined. In this communication, we report the identification of the major metabolic pathways and products of [(3)H]-HNE in rat aortic smooth muscle cells in culture. High-performance liquid chromatography separation of the radioactivity recovered from these cells revealed that a large (60-65%) proportion of the metabolism was linked to glutathione (GSH). Electrospray mass spectrometry showed that glutathionyl-1,4 dihydroxynonene (GS-DHN) was the major metabolite of HNE in these cells. The formation of GS-DHN appears to be due aldose reductase (AR)-catalyzed reduction of glutathionyl 4-hydroxynonanal (GS-HNE), since inhibitors of AR (tolrestat or sorbinil) prevented GS-DHN formation, and increased the fraction of the glutathione conjugate remaining as GS-HNE. Gas chromatography-chemical ionization mass spectroscopy of the metabolites identified a subsidiary route of HNE metabolism leading to the formation of 4-hydroxynonanoic acid (HNA). Oxidation to HNA accounted for 25-30% of HNE metabolism. The formation of HNA was inhibited by cyanamide, indicating that the acid is derived from an aldehyde dehydrogenase (ALDH)-catalyzed pathway. The overall rate of HNE metabolism was insensitive to inhibition of AR or ALDH, although inhibition of HNA formation by cyanamide led to a corresponding increase in the fraction of HNE metabolized by the GSH-linked pathway, indicating that ALDH-catalyzed oxidation competes with glutathione conjugation. These metabolic pathways may be the key regulators of the vascular effects of HNE and oxidized LDL.

Binding of pyridine nucleotide coenzymes to the beta-subunit of the voltage-sensitive K+ channel

The beta-subunit of the voltage-sensitive K(+) (K(v)) channels belongs to the aldo-keto reductase superfamily, and the crystal structure of K(v)beta2 shows NADP bound in its active site. Here we report that K(v)beta2 displays a high affinity for NADPH (K(d) = 0.1 micrometer) and NADP(+) (K(d) = 0.3 micrometer), as determined by fluorometric titrations of the recombinant protein. The K(v)beta2 also bound NAD(H) but with 10-fold lower affinity. The site-directed mutants R264E and N333W did not bind NADPH, whereas, the K(d)(NADPH) of Q214R was 10-fold greater than the wild-type protein. The K(d)(NADPH) was unaffected by the R189M, W243Y, W243A, or Y255F mutation. The tetrameric structure of the wild-type protein was retained by the R264E mutant, indicating that NADPH binding is not a prerequisite for multimer formation. A C248S mutation caused a 5-fold decrease in K(d)(NADPH), shifted the pK(a) of K(d)(NADPH) from 6.9 to 7.4, and decreased the ionic strength dependence of NADPH binding. These results indicate that Arg-264 and Asn-333 are critical for coenzyme binding, which is regulated in part by Cys-248. The binding of both NADP(H) and NAD(H) to the protein suggests that several types of K(v)beta2-nucleotide complexes may be formed in vivo.