Induction of Accommodation Model by Combined RNA Interference Targeting 1,3-Galactosyltransferase Gene and Low-Dose GS-IB4 Lectin In Vitro

OBJECTIVE

This study sought to mimic the interaction of xenograft endothelial cells and human serum in vitro after successfully silencing the expression of porcine alpha1,3-galactosyltransferase (alpha1,3GT) gene by RNA interference (RNAi), and to investigate the possibility of inducing accommodation in vitro by stimulation of alpha-Gal-specific binding lectin, Griffonia simplicifolia isolectin B4 (GS-IB4) and RNAi.

MATERIALS AND METHODS

Various alpha-Gal expression patterns on a pig endothelial cell immortalized line (PED) was achieved by serial doses of small interfering RNA (siRNA) targeting porcinc alpha1,3GT gene. alpha1,3GT-siRNA transfected PEDs were exposed to increasing doses of GS-IB4 lectin (0.5, 2, and 8 microg/mL) for 4 hours before incubation with normal human serum (NHS). Accommodation phenomenon of PEDs in NHS was observed by 51Cr release and antibody/complement binding assays.

RESULTS

With combined RNAi and low-dose GS-IB4 stimulation, PEDs remarkably inhibited complement-mediated cytotoxicity, which showed a better protective effect than using RNAi alone. At a concentration of 2 mug/mL, GS-IB4 exhibited the maximum protective effect. The expression of E-selectin on alpha1,3GT-siRNA transfected PEDs did not differ from that on parental PEDs with heat-inactivated NHS (HINHS) stimulation. Combined with GS-IB4 stimulation, however, it inhibited expression of E-selectin, which was GS-IB4 dose dependent, resulting in mean fluorescence intensity values of 98.5, 42.0, and 36.3 at 0.5, 2, and 8 microg/mL. The mRNA expression of the protective gene HO-1 was significantly up-regulated after treatment with RNAi and low-dose of GS-IB4.

CONCLUSIONS

Combined RNAi and low-dose GS-IB4 induced pig endothelial cell accommodation in vitro. The level of alpha-Gal expression played an important role in the induction of accommodation.

Enantiomeric free radicals and enzymatic control of stereochemistry in a radical mechanism: the case of lysine 2,3-aminomutases

The product of yjeK in Escherichia coli is a homologue of lysine 2,3-aminomutase (LAM) from Clostridium subterminale SB4, and both enzymes catalyze the isomerization of (S)- but not (R)-alpha-lysine by radical mechanisms. The turnover number for LAM from E. coli is 5.0 min(-1), 0.1% of the value for clostridial LAM. The reaction of E. coli LAM with (S)-alpha-[3,3,4,4,5,5,6,6-(2)H8]lysine proceeds with a kinetic isotope effect (kH/kD) of 1.4, suggesting that hydrogen transfer is not rate-limiting. The product of the E. coli enzyme is (R)-beta-lysine, the enantiomer of the clostridial product. Beta-lysine-related radicals are observed in the reactions of both enzymes by electron paramagnetic resonance (EPR). The radical in the reaction of clostridial LAM has the (S)-configuration, whereas that in the reaction of E. coli LAM has the (R)-configuration. Moreover, the conformations of the beta-lysine-related radicals at the active sites of E. coli and clostridial LAM are different. The nuclear hyperfine splitting between the C3 hydrogen and the unpaired electron at C2 shows the dihedral angle to be 6 degrees, unlike the value of 77 degrees reported for the analogous radical bound to the clostridial enzyme. Reaction of (S)-4-thialysine produces a substrate-related radical in the steady state of E. coli LAM, as in the action of the clostridial enzyme. While (S)-beta-lysine is not a substrate for E. coli LAM, it undergoes hydrogen abstraction to form an (S)-beta-lysine-related radical with the same stereochemistry of hydrogen transfer from C2 of (S)-beta-lysine to the 5'-deoxyadenosyl radical as in the action of the clostridial enzyme. The resulting beta-lysyl radical has a conformation different from that at the active site of clostridial LAM. All evidence indicates that the opposite stereochemistry displayed by E. coli LAM is determined by the conformation of the lysine side chain in the active site. Stereochemical models for the actions of LAM from C. subterminale and E. coli are presented.

Biological activities of a novel selective oestrogen receptor modulator derived from raloxifene (Y134)

BACKGROUND AND PURPOSE

Selective oestrogen receptor (ER) modulators (SERMs) are of great value in the treatment of breast cancer and osteoporosis. The aim of this study was to characterize pharmacologically a new class of SERMs synthesized based on the core structure of raloxifene.

EXPERIMENTAL APPROACH

Competitive receptor binding and luciferase-based reporter methods were used to study the bioactivities of raloxifene analogues, followed by efficacy determination in breast cancer cell proliferation assay. ER antagonist effects were investigated in female rats by measuring uterine and mammary gland growth, using wet weight, BrdU incorporation and terminal end bud (TEB) as indicators.

KEY RESULTS

Five analogues, belonging to two different structural series and display higher binding affinities for ERalpha than ERbeta were functionally evaluated. One such analogue, Y134, exhibited potent antagonist activity at ERs in CV-1 cells cotransfected with plasmids containing ERalpha or ERbeta and oestrogen-response element-driven luciferase. The estimated IC(50) value was 0.52 nM for ERalpha and 2.94 nM for ERbeta, comparable to that of raloxifene. Little cytotoxicity was observed at Y134 concentrations below 10 microM. Y134 suppressed oestrogen-stimulated proliferation of ER-positive human breast cancer MCF-7 and T47D cells. At an identical dose, administered to ovariectomized rats, Y134 was more effective than raloxifene at arresting oestrogen-induced outgrowth of TEB and mammary gland DNA synthesis, but their inhibitory effects on the uterus were comparable.

CONCLUSIONS AND IMPLICATIONS

Y134 is a potent ER antagonist with better mammary gland selectivity than raloxifene and shows potential for development as a new SERM for therapeutic use.

Pol I transcription and pre-rRNA processing are coordinated in a transcription-dependent manner in mammalian cells

Pre-rRNA synthesis and processing are key steps in ribosome biogenesis. Although recent evidence in yeast suggests that these two processes are coupled, the nature of their association is unclear. In this report, we analyze the coordination between rDNA transcription and pre-rRNA processing in mammalian cells. We found that pol I transcription factor UBF interacts with pre-rRNA processing factors as analyzed by immunoprecipitations, and the association depends on active rRNA synthesis. In addition, injections of plasmids containing the human rDNA promoter and varying lengths of 18S rDNA into HeLa nuclei show that pol I transcription machinery can be recruited to rDNA promoters regardless of the product that is transcribed, whereas subgroups of pre-rRNA processing factors are recruited to plasmids only when specific pre-rRNA fragments are produced. Our observations suggest a model for sequential recruitment of pol I transcription factors and pre-rRNA processing factors to elongating pre-rRNA on an as-needed basis rather than corecruitment to sites of active transcription.

A fast near-field method for calculations of time-harmonic and transient pressures produced by triangular pistons

Analytical expressions are demonstrated for fast calculations of time-harmonic and transient near-field pressures generated by triangular pistons. These fast expressions remove singularities from the impulse response, thereby reducing the computation time and the peak numerical error with a general formula that describes the near-field pressure produced by any triangular piston geometry. The time-domain expressions are further accelerated by a time-space decomposition approach that analytically separates the spatial and temporal components of the numerically computed transient pressure. Applied to a Hanning-weighted input pulse, time-space decomposition converts each spatio-temporal integral into six spatial integral evaluations at each field point. Time-harmonic and transient calculations are evaluated for an equilateral triangle with sides equal to four wavelengths, and the resulting errors are compared to pressures obtained with exact and approximate implementations of the impulse response method. The results show that the fast near-field method achieves smaller maximum errors and is consistently faster than the impulse response and methods that approximate the impulse response.

Anisotropy and Corotation of Galactic Cosmic Rays

The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments.

Postinjury vascular intimal hyperplasia in mice is completely inhibited by CD34+ bone marrow-derived progenitor cells expressing membrane-tethered anticoagulant fusion proteins

BACKGROUND

Coagulation proteins promote neointimal hyperplasia and vascular remodelling after vessel injury, but the precise mechanisms by which they act in vivo remain undetermined.

OBJECTIVES

This study, using an injury model in which the neointima is derived from bone marrow (BM)-derived cells, compared inhibition of tissue factor or thrombin on either BM-derived or existing vascular smooth muscle cells.

METHODS

Two transgenic (Tg) mouse strains expressing membrane-tethered tissue factor pathway inhibitor (TFPI) or hirudin (Hir) fusion proteins driven by an alpha smooth muscle actin (SMA) promoter were generated (alpha-TFPI-Tg and alpha-Hir-Tg) and the phenotype after wire-induced endovascular injury was compared with that in wild-type (WT) controls.

RESULTS

WT mice developed progressive neointimal expansion, whereas injury in either Tg was followed by repair back to a preinjured state. This was also seen when WT mice were reconstituted with BM from Tg mice but not when Tgs were reconstituted with WT BM, in which injury was followed by slowly progressive neointimal expansion. Injection of CD34+ cells from Tg mice into injured WT mice resulted in the accumulation of fusion protein-expressing cells from day 3 onwards and an absence of neointimal hyperplasia in those areas.

CONCLUSIONS

Neointimal development after wire-induced endovascular injury in mice was completely inhibited when BM-derived cells infiltrating the damaged artery expressed membrane tethered anticoagulant fusion proteins under an alpha-SMA promoter. These findings enhance our understanding of the pathological role that coagulation proteins play in vascular inflammation.

ARF-BP1 as a potential therapeutic target

In this review, we discuss the recent identification of ARF-BP1 (also known as Mule, UREB1, E3^histone, LASU1, and HectH9). ARF-BP1, a HECT domain-containing E3 ubiquitin ligase, interacts with ARF and p53. Its ubiquitin ligase activity is inhibited by ARF. Inactivation of ARF-BP1 stabilised p53 and induced apoptosis. Notably, inactivation of ARF-BP1 also caused cell growth repression in p53-null cells and breast cancer cells with mutant p53. Thus, ARF-BP1 emerges as a novel therapeutic target against cancer regardless of p53 status.

The ratio of circulating osteoprotegerin to RANKL in early rheumatoid arthritis predicts later joint destruction

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic inflammatory disease that may result in debilitating joint deformities with destruction of bone and cartilage. Inflammation is still considered the pivotal inducer of both components of joint damage. Results of recent animal studies suggested a prominent contribution of osteoclastic bone resorption that could be dissociated from inflammation. RANKL and its natural decoy receptor, osteoprotegerin (OPG), play key roles in osteoclast activation. In a group of patients with early RA not treated with disease-modifying drugs, we tested the hypothesis that osteoclast activation, reflected by the serum OPG:RANKL ratio at baseline, is negatively associated with progression of bone damage, independent of inflammation.

METHODS

OPG and RANKL levels, together with a parameter of inflammation (first-year time-averaged erythrocyte sedimentation rate [tESR]), were measured in 92 patients with newly diagnosed early active RA who were participants in a randomized study. The tESR and the OPG:RANKL ratio were evaluated for the ability to predict 5-year radiographic progression of joint damage.

RESULTS

The first-year tESR and the OPG:RANKL ratio, as measured at baseline, independently predicted 5-year radiographic progression of joint damage (both P < or = 0.001). Progression of radiographic damage was greatest in patients with a high tESR and a low OPG:RANKL ratio and was lowest in patients with a low tESR and a high OPG:RANKL ratio.

CONCLUSION

This study in patients with early untreated RA is the first to confirm the findings in animal models of arthritis, that radiographic progression of the bone component of joint destruction is dependent on both inflammation (tESR) and osteoclast activation (the OPG:RANKL ratio).

Therapeutic potential of peptide deformylase inhibitors

Peptide deformylase (PDF) is an attractive target for antibacterial drug discovery. Progress in the biological characterisation of the enzyme, coupled with newly obtained mechanistic and structural insight, enabled the pharmaceutical industry to discover potent PDF inhibitors that can be considered as clinical development candidates for this new class of antibacterial agents. The in vitro and in vivo data for several lead PDF inhibitors suggest that the current PDF inhibitors are most suitable for the treatment of respiratory tract infections and they are not cross-resistant to the current clinically used antibiotics. Two PDF inhibitors, BB-83698 and VIC-104959, have progressed to Phase I clinical trials by intravenous and oral administration, respectively. Both of these compounds show promising in vitro and in vivo efficacy and an excellent safety profile. The pharmacokinetics in humans for both of the compounds suggest the possibility of a twice-daily dosing regimen for clinical use. Thus far, all of the data suggest a promising future for this new class of antibacterial agents.

Triterpenoids from the resin of Styrax tonkinensis and their antiproliferative and differentiation effects in human leukemia HL-60 cells

Four new triterpenoids, 6beta-hydroxy-3-oxo-11alpha,12alpha-epoxyolean-28,13beta-olide (1), 3beta,6beta-dihydroxy-11alpha,12alpha-epoxyolean-28,13beta-olide (2), 3beta,6beta-dihydroxy-11-oxo-olean-12-en-28-oic acid (3), and 3beta-hydroxy-12-oxo-13Halpha-olean-28,19beta-olide (4), and five known triterpenes, 19alpha-hydroxy-3-oxo-olean-12-en-28-oic acid (5), 6beta-hydroxy-3-oxo-olean-12-en-28-oic acid (6), sumaresinolic acid (7), siaresinolic acid (8), and oleanolic acid (9), were isolated from the resin of Styrax tonkinensis. The structures of these triterpenoids were determined by physicochemical and spectroscopic methods. The configuration of compound 4 was confirmed by X-ray crystallographic analysis. All these triterpenoids inhibited HL-60 cell growth with IG(50) values ranging from 8.9 to 99.4 microM. Oleanolic acid (9) was the most effective antiproliferative agent, with an IG(50) value of 8.9 microM. While 3beta,6beta-dihydroxy-11-oxo-olean-12-en-28-oic acid (3) exhibited the least effective growth inhibition among these triterpenoids, it induced HL-60 cells to undergo differentiation as measured by an NBT reduction assay.

The synthesis and anti-proliferative effects of beta-elemene derivatives with mTOR inhibition activity

Fourteen beta-elemene derivatives containing a piperazine, a morpholine, a tetrahydropyrrole, a thiophenylethylamine, or a cyclohexamine group were synthesized. The structures of these beta-elemene derivatives were characterized with IR, 1H NMR, MS, and elemental analyses. All these derivatives had an increased anti-proliferative activity in human cervix epitheloid carcinoma HeLa, gastric carcinoma SGC-7901, and leukemia K562 cells comparing with that of beta-elemene. Among these derivatives, 13,14-bis(cis-3,5-dimethyl-1-piperazinyl)-beta-elemene (IIi), 13,14-bis[2-(2-thiophenyl)ethylamino]-beta-elemene (IIm), and 13,14-bis(cyclohexamino)-beta-elemene (IIn) were the most potent agents. IIi, IIm, and IIn inhibited K562 cell growth with an IG50 below 5 microM that was correlated with mTOR activity inhibition.

Optical percolation and nonlinearity of sputtered Ag island films

The fractal dimension Df and the critical parameter nu of the sputtered percolation Ag island films are measured to be about 1.57 and 1.15, respectively. A modified Z-scan method including both transmittance Z-scan and reflection Z-scan is proposed to measure the pure nonlinear absorption of the semi-continuous Ag films near the percolation threshold. As the microstructure of the sputtered Ag films varies from the discontinuous to the continuous, the linear absorbance decreases from 0.97 to 0.58 while the nonlinear absorption coefficient changes from -1.4x10-5m/W to -4.6x10-6m/W at the wavelength of 800nm. The largest nonlinear absorption coefficient beta of the sputtered Ag films is obtained in the discontinuous film near the percolation threshold, which is mainly contributed by the large enhancement of local field of dis-continuous Ag particles.

Employment of liver tissue slice analysis to assay hepatotoxicity linked to replicative and nonreplicative adenoviral agents

Whereas virotherapy has emerged as a novel and promising approach for neoplastic diseases, appropriate model systems have hampered preclinical evaluation of candidate conditionally replicative adenovirus agents (CRAds) with respect to liver toxicity. This is due to the inability of human viral agents to cross species. We have recently shown the human liver tissue slice model to be a facile means to validate adenoviral replication. On this basis, we sought to determine whether our ex vivo liver tissue slice model could be used to assess CRAd-mediated liver toxicity. We analyzed and compared the toxicity of a conditionally replicative adenovirus (AdDelta24) to that of a replication incompetent adenovirus (Adnull [E1-]) in mouse and human liver tissue slices. To accomplish this, we examined the hepatic apoptosis expression profile by DNA microarray analyses, and compared these results to extracellular release of aminotransferase enzymes, along with direct evidence of apoptosis by caspase-3 immunhistochemical staining and TUNEL assays. Human and mouse liver tissue slices demonstrated a marked increase in extracellular release of aminotransferase enzymes on infection with AdDelta24 compared to Adnull. AdDelta24-mediated liver toxicity was further demonstrated by apoptosis induction, as detected by caspase-3 immunohistochemical staining, TUNEL assay and microarray analysis. In conclusion, concordance of CRAd-mediated apoptosis in both the human and the mouse liver tissue slice models was demonstrated, despite the limited replication ability of CRAds in mouse liver slices. The results of this study, defining the CRAd-mediated apoptosis gene expression profiles in human and mouse liver, may lay a foundation for preclinical liver toxicity analysis of CRAd agents.

ECL cell histamine mobilization and parietal cell stimulation in the rat stomach studied by microdialysis and electron microscopy

AIM

Gastrin stimulates acid secretion by mobilizing histamine from enterochromaffin-like (ECL) cells that occur predominantly at the base of the gastric glands. The parietal cells occur higher up in the glands nearer to the gastric lumen. The present study was performed to assess whether histamine is transported from the ECL cell via the microcirculation (endocrine route) or local diffusion (paracrine route).

METHODS

Totally isolated, vascularly perfused, rat stomachs were examined both in basal and gastrin-stimulated state. Histamine concentrations, determined by radioimmunoassay in venous effluent and microdialysate from an indwelling probe in the submucosa, were monitored over a period of 240 min. Gastrin-17 was infused through an arterial catheter for 120 min. The parietal cells were examined by electron microscopy, and the percentage of actively secreting parietal cells (displaying secretory canaliculi) in four regions along the glands (basal to surface, zones I-IV) was determined.

RESULTS

Gastrin stimulated acid secretion and histamine release as well as parietal cell activation. Upon gastrin stimulation, histamine concentration in the microdialysate was 2.5-fold higher than in the venous effluent (P = 0.008). The parietal cells in the upper part of the gland (zone III) were found to be activated the most.

CONCLUSION

As the histamine concentrations were higher in the tissue (microdialysate) than in blood, histamine seems to reach the parietal cells via the paracrine route. The fraction of active parietal cells seems to depend more on the age of the parietal cells than on the distance from the ECL cell.

Maternal anxiety and ultrasound markers for aneuploidy in a multiethnic population

OBJECTIVE

Discussion of isolated ultrasound (US) markers for fetal aneuploidy can provoke significant patient anxiety. The objective of this study is to quantify maternal anxiety associated with the detection of these markers.

METHODS

All patients undergoing routine second-trimester US examination for fetal anatomical survey over a one-year period were administered the State-Trait Anxiety Inventory (STAI) for Adults before and after the procedure. Women with isolated fetal markers for aneuploidy were notified of the findings but discouraged from pursuing amniocentesis. Rates of normal US examination, aneuploidy markers, anomalies, amniocentesis, and pregnancy outcomes were assessed across the ethnic groups. Pre- and post-ultrasound STAI surveys were scored and standardized with previously established norms. Student t-tests, Chi-square, and analysis of variance (ANOVA) were used where appropriate.

RESULTS

Among the 798 patients tested, 57% were Hispanic, 30% were Asian, 6% were Black, and 7% were White. Maternal anxiety level was decreased in women after a normal US. The anxiety level increased with aneuploidy markers and was the highest with anomalies. Aneuploidy markers were more common among Hispanic and Asian fetuses, without any associated aneuploidy. Women with isolated aneuploidy markers underwent amniocentesis as often as women with advanced maternal age.

CONCLUSION

The detection and communication of isolated aneuploidy markers is associated with increased maternal anxiety and unnecessary amniocentesis.