Induction of apoptosis in sea bream fibroblasts by Vibrio harveyi haemolysin and evidence for an anti-apoptotic role of heat shock protein 70

In this study, we exposed black sea bream, Mylio macrocephalus (Basilewsky), fibroblast (BSF) and silver sea bream, Sparus sarba Forsskål, fibroblast (SSF) cell lines to a recombinant Vibrio harveyi haemolysin (VHH) and investigated mechanisms involved in apoptosis. A decrease in mitochondrial membrane potential, followed by an increase in caspase 3 activity, occurred within 2-8 h of VHH exposure, in both cell lines; however, VHH did not alter cellular levels of reactive oxygen species. As heat shock protein 70 (HSP70) is known to prevent the onset of apoptosis in certain mammalian cells, we aimed to test whether such a protective effect is operative in VHH-exposed fibroblasts. The amounts of HSP70 were elevated in SSF and BSF via an acute heat shock or an acute heat shock followed by a 6 h recovery. It was found that the VHH-mediated reduction in mitochondrial membrane potential was suppressed in cells that had a 6 h post-heat shock recovery, and the protective effect of heat shock-induced HSP70 was attenuated following treatment of cells with the HSP70 inhibitor, quercetin. This study demonstrates how haemolysin causes cell death via induction of apoptosis and provides evidence as to the role of HSP70 as an anti-apoptotic factor.

Acute kidney injury in Chinese patients with lupus nephritis: a large cohort study from a single center

OBJECTIVE

In this study we assess clinicopathologic characteristics, treatment and prognosis of acute kidney injury (AKI) in a large cohort of Chinese patients with lupus nephritis.

METHODS

The clinical, laboratory, renal histopathology, treatment and outcome data were retrospectively collected and compared between lupus nephritis patients with and without AKI. The impact of AKI on renal outcome was evaluated.

RESULTS

Among 322 patients with renal biopsy-proven lupus nephritis, 66 (20.5%) were identified as AKI. Male predominance was observed in patients with AKI (p < 0.001). In comparison with the non-AKI group, patients with AKI had significantly higher proportions of serositis (p < 0.001), neurologic disorder (p = 0.026), anemia (p < 0.001), thrombocytopenia (p = 0.013) and nephrotic syndrome (p = 0.011), but significant lower serum C3 (p < 0.001). The Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, renal pathological activity indices and chronicity indices were significantly higher in the AKI group (p < 0.001 in all cases). Regarding outcome, the AKI group had a significantly poorer renal outcome compared with non-AKI group (p < 0.001). In the AKI group, patients with crescentic glomerulonephritis and thrombotic microangiopathy had the worst renal outcome. AKI was an independent risk factor for renal outcome (hazard ratio [HR] = 5.819, 95% confidence interval 2.411-14.044, p < 0.001).

CONCLUSIONS

AKI is common in lupus nephritis and is an independent risk factor for renal outcome.

Study of the MLB parameterisation for change in surface solar irradiance with sun zenith angle in clear sky

Abstract. The MLB parameterisation (Modified Lambert-Beer, Mueller et al., 2004) describes the change in SSI with sun zenith angle (SZA) in clear-sky conditions. It applies to the direct and global SSI as well as their spectral distribution. We assess its performances by comparing its results to the outputs of the radiative transfer model libRadtran and standard interpolation procedures. The standard two-point fitting MLB function performs very well at SZA between 0° and 60° and fairly bad from 60° to 89.9°. A parameterisation made of four MLBs for four intervals (0°, 60°), (60°, 75°), (75°, 85°) and (85°, 89.9°) is also tested. This piecewise MLB parameterisation exhibits satisfactory performances at any SZA and outperforms standard linear interpolation techniques. 95 % of errors in global SSI are less than 1 W m−2 for each band and less than 5 W m−2 for total irradiance.

Solar irradiance in clear atmosphere: study of parameterisations of change with altitude

Abstract. Parameterisation of changes of the solar irradiance at ground level with a specific variable (e.g. solar zenithal angle, aerosol optical depth, altitude, etc.) is often used in operational processes because it saves computational time. This paper deals with the modelling of the vertical profile of downwelling solar irradiance for the first two kilometres above ground in clear sky conditions. Two analytical parameterisations are evaluated for direct and global irradiance in spectral bands as well as for the total irradiance. These parameterisations reproduce the vertical profile with good accuracy for global spectral irradiance and are less accurate for direct component, especially in turbid atmosphere. A piecewise linear interpolation technique using irradiance values known at surface and 4 altitudes every 500 m performs better in any case.

Down-modulation of cancer targets using locked nucleic acid (LNA)-based antisense oligonucleotides without transfection

Usually, small interfering RNAs and most antisense molecules need mechanical or chemical delivery methods to down-modulate the targeted mRNA. However, these delivery approaches complicate the interpretations of biological consequences. We show that locked nucleic acid (LNA)-based antisense oligonucleotides (LNA-ONs) readily down-modulate genes of interest in multiple cell lines without any delivery means. The down-modulation of genes was quick, robust, long-lasting and specific followed by potent down-modulation of protein. The efficiency of the effect varied among the 30 tumor cell lines investigated. The most robust effects were found in those cells where nuclear localization of the LNA-ON was clearly observed. Importantly, without using any delivery agent, we demonstrated that HER3 mRNA and protein could be efficiently down-modulated in cells and a tumor xenograft model. These data provide a simple and efficient approach to identify potential drug targets and animal models. Further elucidation of the mechanism of cellular uptake and trafficking of LNA-ONs may enhance not only the therapeutic values of this platform but also antisense molecules in general.

Vortex phase diagram of the layered superconductor Cu0.03TaS2 for H is parallel to c

The magnetization and anisotropic electrical transport properties have been measured in high quality Cu(0.03)TaS(2) single crystals. A pronounced peak effect has been observed, indicating that high quality and homogeneity are vital to the peak effect. A kink has been observed in the magnetic field, H, dependence of the in-plane resistivity ρ(ab) for H is parallel to c, which corresponds to a transition from activated to diffusive behavior of the vortex liquid phase. In the diffusive regime of the vortex liquid phase, the in-plane resistivity ρ(ab) is proportional to H(0.3), which does not follow the Bardeen-Stephen law for free flux flow. Finally, a simplified vortex phase diagram of Cu(0.03)TaS(2) for H is parallel to c is given.

Thrombomodulin improves early outcomes after intraportal islet transplantation

Primary islet nonfunction due to an instant blood mediated inflammatory reaction (IBMIR) leads to an increase in donor islet mass required to achieve euglycemia. In the presence of thrombin, thrombomodulin generates activated protein C (APC), which limits procoagulant and proinflammatory responses. In this study, we postulated that liposomal formulations of thrombomodulin (lipo-TM), due to its propensity for preferential uptake in the liver, would enhance intraportal engraftment of allogeneic islets by inhibiting the IBMIR. Diabetic C57BL/6J mice underwent intraportal transplantation with B10.BR murine islets. In the absence of treatment, conversion to euglycemia was observed among 29% of mice receiving 250 allo-islets. In contrast, a single infusion of lipo-TM led to euglycemia in 83% of recipients (p = 0.0019). Fibrin deposition (p < 0.0001), neutrophil infiltration (p < 0.0001), as well as expression TNF-alpha and IL-beta (p < 0.03) were significantly reduced. Significantly, thrombotic responses mediated by human islets in contact with human blood were also reduced by this approach. Lipo-TM improves the engraftment of allogeneic islets through a reduction in local thrombotic and inflammatory processes. As an enzyme-based pharmacotherapeutic, this strategy offers the potential for local generation of APC at the site of islet infusion, during the initial period of elevated thrombin production.

Generation of finite wave trains in excitable media

Spatiotemporal control of excitable media is of paramount importance in the development of new applications, ranging from biology to physics. To this end, we identify and describe a qualitative property of excitable media that enables us to generate a sequence of traveling pulses of any desired length, using a one-time initial stimulus. The wave trains are produced by a transient pacemaker generated by a one-time suitably tailored spatially localized finite amplitude stimulus, and belong to a family of fast pulse trains. A second family, of slow pulse trains, is also present. The latter are created through a clumping instability of a traveling wave state (in an excitable regime) and are inaccessible to single localized stimuli of the type we use. The results indicate that the presence of a large multiplicity of stable, accessible, multi-pulse states is a general property of simple models of excitable media.

Spin valve effect and magnetoresistivity in single crystalline Ca3Ru2O7

The laminar perovskite Ca3Ru2O7 naturally forms ferromagnetic double layers of alternating moment directions, as in the spin-valve superlattices. The mechanism of the huge magnetoresistive effect in the material has been controversial due to a lack of clear understanding of various magnetic phases and phase transitions. In this neutron diffraction study in a magnetic field, we identify four different magnetic phases in Ca3Ru2O7 and determine all first-order and second-order phase transitions between them. The spin-valve mechanism then readily explains the dominant magnetoresistive effect in Ca3Ru2O7.

Protective role of tretinoin and N-acetyl-L-cysteine from antiproliferative action of cigarette smoke extract on alveolar epithelial cells

To investigate the mechanisms by which tretinoin and N-acetyl-L-cysteine (NAC) reverse the growth inhibition of alveolar epithelial cells induced by cigarette smoke extract (CSE), MTT assay was used to evaluate cell viability. It was observed that both tretinoin and NAC could restore the viability of CSE-inhibited A549 cells. By incubation with fluorescent indicator H2DCFDA, it was documented that CSE-stimulated accumulation of intracellular reactive oxygen species (ROS) was obviously decreased by tretinoin or NAC. Furthermore, using semi-quantitative and real-time quantitative RT-PCR as well as western blot methods, high expression of insulin-like growth factor binding protein-2 (IGFBP-2) in A549 cells treated with CSE was found at both transcriptional and protein levels, and concomitant with the restoration of cell growth after treatment with tretinoin or NAC, down regulation of IGFBP-2 was observed. From the present study, it is concluded that both RA and NAC can antagonize CSE-induced growth arrest of alveolar epithelial cells and that down regulation of IGFBP-2 may play an important role in the process.

A new method of constructing CD20/CD22 bispecfic antibody fusion proteins with improved direct lymphoma cytotoxicity compared to rituximab

2536

Background: Anti-CD20 and anti-CD22 monoclonal antibodies (MAbs) have been shown to have antitumor activity in non-Hodgkin’s lymphoma (NHL) patients. Since preclinical and clinical trials also suggested that combining CD20 and CD22 MAbs, which have different mechanisms of action, could improve antitumor activity without a commensurate increase in toxicity, we hypothesized that a therapeutic advantage may be achieved with bispecific MAbs that bind simultaneously to both CD20 and CD22. Methods: A new platform technology, termed the Dock and Lock method (DNL), was successfully applied to produce a trivalent bispecific antibody, named TF3, which comprises two recombinant Fab fragments of hA20 (humanized anti-CD20 MAb; IMMU-106) stably tethered to one recombinant Fab fragment of epratuzumab (humanized anti-CD22 MAb; IMMU-103) via the specific interaction between a dimerization-and-docking domain and an anchoring domain appended to hA20 and epratuzumab, respectively. The cytotoxicity of TF3 was evaluated by cell-based assays using NHL cell lines. Results: TF3 is stable in both human and mouse sera andexhibitsthe samebinding affinity as hA20 IgG or epratuzumab Fab by competitive ELISA. With a 3-day MTT assay, TF3 at 10 nM inhibited 50% and 60% growth of Daudi and Ramos cells, respectively. Further, the observed anti-proliferative activity increased synergistically to >90% in the presence of anti-IgM (0.1 μg/mL). Results from a cell counting assay also demonstrated the ability of TF3 at 1 μM to completely inhibit the growth of Daudi and the potency of TF3 at 1 nM was comparable to that of rituximab at 1 μM under the same experimental conditions, reflecting a 1000-fold enhancement. Conclusions: These findings, to be extended by ongoing in vivo studies, suggest that the new DNL platform technology for making bispecific antibody fusion proteins provided a CD20/CD22 binding protein that is significantly more potent than rituximab in an in vitro NHL direct cytotoxicity assay.

[Table: see text]

Expression of the SNT-1/FRS2 phosphotyrosine binding domain inhibits activation of MAP kinase and PI3-kinase pathways and antiestrogen resistant growth induced by FGF-1 in human breast carcinoma cells

Fibroblast growth factor (FGF) signaling can bypass the requirement for estrogen receptor (ER) activation in the growth of ER-positive (ER+) breast cancer cells. Fibroblast growth factor-1 stimulation leads to phosphorylation of the adaptor protein Suc1-associated neurotrophic factor-induced tyrosine-phosphorylated target (SNT-1) on C-terminal tyrosine residues, whereas it is constitutively bound through its N-terminal phosphotyrosine-binding domain (PTB) to FGF receptors (FGFRs). By expressing the PTB domain of SNT-1 (SNT-1 PTB) in an inducible manner in an ER+ breast carcinoma line, ML20, we asked whether we could uncouple FGFR activation from its downstream signaling components and abrogate FGF-1-induced antiestrogen-resistant growth. Induction of SNT-1 PTB resulted in a significant decrease of FGF-1-dependent tyrosine phosphorylation of endogenous SNT-1, strong inhibition of complex formation between SNT-1, Gab-1 and Sos-1, and reduced activation of Ras, mitogen-activated protein kinase (MAP kinase), and Akt. SNT-1 PTB also inhibited the phosphorylation of p70S6K on Thr421/Ser424 and Ser411, which may result from the abrogation of MAP kinase activity. Moreover, we also observed a decreased phosphorylation of the MAP kinase-independent site Thr389. This may reflect both inhibition of PI-3 kinase pathways and mammalian target of rapamycin (mTOR)-dependent signaling, as the phosphorylation of Thr389 site was sensitive to treatment with the PI3-K and mTOR inhibitors, LY294002 and rapamycin, respectively. Collectively these results suggest that SNT-1 plays a pivotal role in FGF-dependent activation of the Ras-MAP kinase, PI-3 kinase, and mTOR pathways in these cells. Fibroblast growth factor-1 dependent colony formation of ML20 cells in media containing the pure antiestrogen ICI 182,780 was also markedly inhibited upon induction of SNT-1 PTB, suggesting that blockade of FGFR-SNT-1 interactions might abrogate FGF-mediated antiestrogen resistance in breast cancers.

[Effect of neurotropin on brain edema induced by permanent focal cerebral ischemia in rats and collateral ventricular injection of carrageenan in mice]

Neurotropin, an inhibitor of the kallikrein-kinin system, has been used as an analgesic and anti-allergic drug in the clinic. The aims of this study are to evaluate the effect of neurotropin on brain edema induced by permanent focal cerebral ischemia in rats and collateral ventricular injection of carrageenan in mice and its mechanism. Drugs were given i.v. 15 minutes after middle cerebral artery occlusion in rats and immediately after carrageenan injection in mice. Brain water content was determined by wet/dry weight ratio. Results showed that neurotropin could reduce the brain edema induced by permanent focal cerebral ischemia in rats and collateral ventricular injection of carrageenan in mice at doses of 3.0, 6.0, 30.0 and 30.0 NU.kg-1 body weight. It also suggests that neurotropin reduced ischemic brain edema via inhibiting the kallikrein-kinin system.

Muscle-derived cell-mediated ex vivo gene therapy for urological dysfunction

We have tested the feasibility of muscle-based gene therapy and tissue engineering for urological dysfunction using highly purified muscle-derived cells (MDC) that display stem cell characteristics. We then explored the potential use of these MDC as an alternative therapy for the treatment of impaired detrusor contractility. The MDC were genetically engineered to express the gene encoding beta-galactosidase and injected into the bladder walls of SCID mice. The injected bladders were harvested at various time-points after injection and assayed for beta-galactosidase activity; the presence of myofibers within the injected tissue was determined by detection of fast myosin heavy chain isoform (MyHCs). We have demonstrated that the injected MDC are capable of not only surviving in the lower urinary tract, but also improving the contractility of the bladder following an induced injury. Two potential mechanisms can be used to explain this finding. First, we have observed that some of the beta-galactosidase-expressing cells expressed alpha-smooth muscle actin, suggesting a differentiation into smooth muscle. Second, a stain for acetylcholine receptors (AChRs), which identifies the location of neuromuscular junctions, revealed that the myofibers derived from the doner cells became innervated into the bladder as early as 2 weeks after injection. These results suggest that gene therapy and tissue engineering based on MDC potentially can be used for urological dysfunction.

Pretargeting for cancer radioimmunotherapy with bispecific antibodies: role of the bispecific antibody's valency for the tumor target antigen

The use of a divalent effector molecule improves bispecific antibody (bsMAb) pretargeting by enabling the cross-linking of monovalently bound bsMAb on the cell surface, thereby increasing the functional affinity of a bsMAb. In this work, it was determined if a bsMAb with divalency for the primary target antigen would improve bsMAb pretargeting of a divalent hapten. The pretargeting of a (99m)Tc-labeled divalent DTPA-peptide, IMP-192, using a bsMAb prepared by chemically coupling two Fab' fragments, one with monovalent specificity to the primary target antigen, carcinoembryonic antigen (CEA), and to indium-loaded DTPA [DTPA(In)], was compared to two other bsMAbs, both with divalency to CEA. One conjugate used the whole anti-CEA IgG, while the other used the anti-CEA F(ab')(2) fragment to make bsMAbs that had divalency to CEA, but with different molecular weights to affect their pharmacokinetic behavior. The rate of bsMAb blood clearance was a function of molecular weight (IgG x Fab' < F(ab')(2) x Fab' < Fab' x Fab' conjugate). The IgG x Fab' bsMAb conjugate had the highest uptake and longest retention in the tumor. However, when used for pretargeting, the F(ab')(2) x Fab' conjugate allowed for superior tumor accretion of the (99m)Tc-IMP-192 peptide, because its more rapid clearance from the blood enabled early intervention with the radiolabeled peptide when tumor uptake of the bsMAb was at its peak. Excellent peptide targeting was also seen with the Fab' x Fab' conjugate, albeit tumor uptake was lower than with the F(ab')(2) x Fab' conjugate. Because the IgG x Fab' bsMAb cleared from the blood so slowly, when the peptide was given at the time of its maximum tumor accretion, the peptide was captured predominantly by the bsMAb in the blood. Several strategies were explored to reduce the IgG x Fab' bsMAb remaining in the blood to take advantage of its 3-4-fold higher tumor accretion than the other bsMAb conjugates. A number of agents were tested, including those that could clear the bsMAb from the blood (e.g., galactosylated or nongalactosylated anti-id antibody) and those that could block the anti-DTPA(In) binding arm [e.g., DTPA(In), divalent-DTPA(In) peptide, and DTPA coupled to bovine serum albumin (BSA) or IgG]. When clearing agents were given 65 h after the IgG x Fab' conjugate (time of maximum tumor accretion for this bsMAb), (99m)Tc-IMP-192 levels in the blood were significantly reduced, but a majority of the peptide localized in the liver. Increasing the interval between the clearing agent and the time the peptide was given to allow for further processing of the bsMAb-clearing agent complex did not improve targeting. At the dose and level of substitution tested, galacosylated BSA-DTPA(In) was cleared too quickly to be an effective blocking agent, but BSA- and IgG-DTPA(In) conjugates were able to reduce the uptake of the (99m)Tc-IMP-192 in the blood and liver. Tumor/nontumor ratios compared favorably for the radiolabeled peptide using the IgG x Fab'/blocking agent combination and the F(ab')(2) x Fab' (no clearing/blocking agent), and peptide uptake 3 h after the blocking agent even exceeded that of the F(ab')(2) x Fab'. However, this higher level of peptide in the tumor was not sustained over 24 h, and actually decreased to levels lower than that seen with the F(ab')(2) x Fab' by this time. These results demonstrate that divalency of a bsMAb to its primary target antigen can lead to higher tumor accretion by a pretargeted divalent peptide, but that the pharmacokinetic behavior of the bsMAb also needs to be optimized to allow for its clearance from the blood. Otherwise, blocking agents will need to be developed to reduce unwanted peptide uptake in normal tissues.

A kinetic study on the pairwise competition reaction of alpha-diazo esters with rhodium(II) catalysts: implication for the mechanism of Rh(II)-carbene transfer

The relative rate constants for the Rh(II)-mediated diazo decomposition of a series of para- or meta-substituted diazophenylacetates were measured through intermolecular competition. The kinetic data were further subjected to Hammett correlation analysis and were found to have better linear correlation with sigma(+). Reaction constants for four Rh(II) catalysts have been obtained, Rh(2)(OAc)(4) (rho = -1.29 with sigma(+), r = -0.99), Rh(2)(Ooct)(4) (rho = -1.31 with sigma(+), r = -0.99), Rh(2)(acam)(4) (rho = -1.18 with sigma(+), r = -0.99), Rh(2)(O(2)CCF(3))(4) (rho = -1.46 with sigma(+), r = -0.99). The mechanistic implications of these data are discussed.

Mechanisms of ascorbic acid recycling in human erythrocytes

Vitamin C, or ascorbic acid, is efficiently recycled from its oxidized forms by human erythrocytes. In this work the dependence of this recycling on reduced glutathione (GSH) was evaluated with regard to activation of the pentose cycle and to changes in pyridine nucleotide concentrations. The two-electron-oxidized form of ascorbic acid, dehydroascorbic acid (DHA) was rapidly taken up by erythrocytes and reduced to ascorbate, which reached intracellular concentrations as high as 2 mM. In the absence of D-glucose, DHA caused dose-dependent decreases in erythrocyte GSH, NADPH, and NADH concentrations. In the presence of 5 mM D-glucose, GSH and NADH concentrations were maintained, but those of NADPH decreased. Reduction of extracellular ferricyanide by erythrocytes, which reflects intracellular ascorbate recycling, was also enhanced by D-glucose, and ferricyanide activated the pentose cycle. Diethylmaleate at concentrations up to 1 mM was found to specifically deplete erythrocyte GSH by 75-90% without causing oxidant stress in the cells. Such GSH-depleted erythrocytes showed parallel decreases in their ability to take up and reduce DHA to ascorbate, and to reduce extracellular ferricyanide. These results show that DHA reduction involves GSH-dependent activation of D-glucose metabolism in the pentose cycle, but that in the absence of D-glucose DHA reduction can also utilize NADH.

[Mapping the interaction site of Rpb2 and Rpb3 subunit of fission yeast RNA polymerase II]

To map the interacting site of subunit Rpb2 to subunit Rpb3 of RNA polymerase II in fission yeast Schizosaccharomyces pombe, the yeast two-hybrid system was employed in this paper to screen the interacting clones between Rpb2 and Rpb3.4 fragments of Rpb2 cDNA were cloned into the Ga14 BD vector pAS2. The 4 clones were named as pAS2 Rpb2-1, 2-2, 2-3 and 2-4, respectively. The complete cDNA of Rpb3 was cloned into the Gal 4 AD vector pGADGH. The clone was named as pGADGH Rpb3. The two-hybrid plasmids pGADGH Rpb3 and pAS2Rpb2-1, 2-2, 2-3 or 2-4 respectively were cotransformed into host cell yeast Y190. The interaction positive cotransformants were identified by beta-gal activity assay. The beta-gal positive cotransformants were selected from pGADGH Rpb3 and pAS2Rpb2-4 two-hybrid system. DNA sequencing and alignment results showed that the interacting site of Rpb2 to Rpb3 located within the fragment from base 2701 to 2966 of Rpb2 cDNA, or within the C-termini polypeptide from amino acid 902 to 989 of Rpb2 protein.

Cloning, molecular characterization, and application of rice epiphytic Bacillus pumilus promoter fragments

To establish a constitutive, high-efficiency expression system for Bacillus pumilus (B.P), we cloned random chromosomal DNA into promoter probe shuttle vector ECE7 and selected for strong promoter activity by chloramphenicol resistance of transformed B. pumilus cells. The nucleotide sequences of nine chromosomal fragments were determined. These DNA fragments range from 300 to 2200 bp in size. The transcription strength of these promoters was estimated by determination of CAT enzyme production in both E. coli and B. pumilus. Transcription start (TS) sites of the cat mRNA were located by primer extension by using total RNA. Preliminary analysis showed that three of the promoter sequences contain -35 and -10 regions like E. coli RNA polymerase sigma70 and B. subtilis sigma43 consensus sequences. One is similar to B. subtilis sigma29, the other two have no conserved sequences like any of the typical consensus sequences of the known sigma factors so far. To estimate the feasibility of the utilization of these promoters, one promoter fragment was subcloned and used to drive the expression of green fluorescent protein (GFP) in B. pumilus cells. This is the first report of B. pumilus promoters randomly cloning from total DNA and molecular analysis of their consensus sequences.

Requirement for GSH in recycling of ascorbic acid in endothelial cells

Ascorbic acid may be involved in the defense against oxidant stress in endothelial cells. Such a role requires that the cells effectively recycle the vitamin from its oxidized forms. In this work, we studied the ability of cultured bovine aortic endothelial cells (BAECs) to take up and reduce dehydroascorbic acid (DHA) to ascorbate, as well as the dependence of ascorbate recycling on intracellular GSH. BAECs took up and reduced DHA to ascorbate much more readily than they took up ascorbate. Although BAECs in culture did not contain ascorbate, ascorbate accumulated to concentrations of 2-3 mM in BAECs following incubation with 400 microM DHA. Extracellular ferricyanide oxidized intracellular ascorbate, which was recycled by the cells. Reduction of DHA, either when added to the cells or when generated in response to ferricyanide, caused significant decreases in intracellular GSH concentrations. Depletion of intracellular GSH with 1-chloro-2,4-dinitrobenzene, diethylmaleate, and diamide almost abolished the ability of the cells to reduce DHA to ascorbate. DHA reduction by thioredoxin reductase was evident in dialyzed cell extracts, but occurred at rates far lower than direct GSH reduction of DHA. These results suggest that maximal rates of DHA reduction, and thus recycling of ascorbate from DHA, are dependent upon GSH in these cells.

1,2-aryl and 1,2-hydride migration in transition metal complex catalyzed diazo decomposition: a novel approach to alpha-aryl-beta-enamino esters

N-Tosyl diazoketamines were prepared by addition of the ethyl alpha-diazoacetate anion to N-sulfonylimines. The diazo decomposition of the diazoketamines with Rh(2)(OAc)(4) complex resulted in aryl migration to give alpha-aryl-beta-enamino esters in good yields and high stereoselectivity. The effect of the catalysts on the migratory aptitude of 1,2-aryl over 1,2-hydride migration was studied. A reaction mechanism involving a "bridged" phenonium ion is proposed. Reaction: see text.

Effect of anti-IL-6 and anti-10 monoclonal antibodies on the suppression of the normal T lymphocyte mitogenic response by steady state sickle cell disease sera

Previously published work has shown that sera from healthy sickle cell disease (SCD) patients inhibits normal lymphocyte mitogenic response to phytohemagglutinin (PHA) in vitro. The current study is to attempt to ascertain what effect antibody to type 2 cytokines, interleukin (IL)-6 and 10, have on the suppression of lymphocyte PHA response by SCD sera. Peripheral blood mononuclear cells (PBMC), separated by density gradient were obtained from 2 healthy normal donors. Sera from 50 healthy SCD patients, 50 normal healthy controls and pooled normal O, Rh+ (O+) sera were utilized in standard in vitro PHA stimulation of PBMC cultures. Mitogenic responses were expressed as mean counts per minute (cpm) of triplicate cultures. Fifty triplicate cultures of PHA stimulated normal PBMC were done with 10% normal pooled O+, normal control and SCD steady state sera only. In addition 50 cultures were done with SCD sera containing 1 microg/ml of anti-IL-6 monoclonal antibody, as well as 28 SCD serum cultures containing 1 microg/ml of anti-IL-10 monoclonal antibody. The final 11 SCD serum culture experiments contained a combination of both anti-IL-6 and anti-IL-10 antibody, each at the concentration of 1 microg/ml. Results revealed > 15% suppression of mitogenic response in the SCD sera supplemented cultures as compared to control sera in 47/50 (94%) and in 40/50 (80%) of normal pooled O+, as calculated by mean cpm. The degree of suppression ranged from 17% to 98% in individual experiments. The addition of anti IL-6 antibody alone significantly improved mean cpm (> 20%) in 19/50 (38%) of SCD serum responses compared to O+ sera and 23/50 (46%) of control sera. Complete correction occurred in 9/50 (18%) of all SCD serum suppressions as compared to O+ sera and 6/50 (12%) when compared to control sera. Similarly, anti-IL-10 antibody decreased suppression of the mean cpm of SCD serum cultures in 18/28 (64%) and completely corrected 3/18 (11%). The combined antibody data revealed >20% increase in mean cpm in 10/11(91%) experiments. Inhibitors of mitogenic response were present in a significant percentage of the SCD sera utilized in the present study. The significant corrective effects of both monoclonal antibodies would seem to support the original hypothesis that high circulating levels of type 2 cytokines may represent the cell-mediated dependent inhibitory factors expressed in the sera of many healthy SCD patients.

Direct solar spectral irradiance and transmittance measurements from 350 to 2500 nm

A radiometrically stable, commercially available spectroradiometer was used in conjunction with a simple, custom-designed telescope to make spectrally continuous measurements of solar spectral transmittance and directly transmitted solar spectral irradiance. The wavelength range of the instrument is 350-2500 nm and the resolution is 3-11.7 nm. Laboratory radiometric calibrations show the instrument to be stable to better than 1.0% over a nine-month period. The instrument and telescope are highly portable, can be set up in a matter of minutes, and can be operated by one person. A method of absolute radiometric calibration that can be tied to published top-of-the-atmosphere (TOA) solar spectra in valid Langley channels as well as regions of strong molecular absorption is also presented. High-altitude Langley plot calibration experiments indicate that this technique is limited ultimately by the current uncertainties in the TOA solar spectra, approximately 2-3%. Example comparisons of measured and modtran-modeled direct solar irradiance show that the model can be parameterized to agree with measurements over the large majority of the wavelength range to the 3% level for the two example cases shown. Side-by-side comparisons with a filter-based solar radiometer are in excellent agreement, with a mean absolute difference of tau = 0.0036 for eight overlapping wavelengths over three experiment days.

Patterns of wave break during ventricular fibrillation in isolated swine right ventricle

Several different patterns of wave break have been described by mapping of the tissue surface during fibrillation. However, it is not clear whether these surface patterns are caused by multiple distinct mechanisms or by a single mechanism. To determine the mechanism by which wave breaks are generated during ventricular fibrillation, we conducted optical mapping studies and single cell transmembrane potential recording in six isolated swine right ventricles (RV). Among 763 episodes of wave break (0.75 times x s(-1) x cm(-2)), optical maps showed three patterns: 80% due to a wave front encountering the refractory wave back of another wave, 11.5% due to wave fronts passing perpendicular to each other, and 8.5% due to a new (target) wave arising just beyond the refractory tail of a previous wave. Computer simulations of scroll waves in three-dimensional tissue showed that these surface patterns could be attributed to two fundamental mechanisms: head-tail interactions and filament break. We conclude that during sustained ventricular fibrillation in swine RV, surface patterns of wave break are produced by two fundamental mechanisms: head-tail interaction between waves and filament break.

Recycling of the ascorbate free radical by human erythrocyte membranes

Reduction of the ascorbate free radical (AFR) at the plasma membrane provides an efficient mechanism to preserve the vitamin in a location where it can recycle alpha-tocopherol and thus prevent lipid peroxidation. Erythrocyte ghost membranes have been shown to oxidize NADH in the presence of the AFR. We report that this activity derives from an AFR reductase because it spares ascorbate from oxidation by ascorbate oxidase, and because ghost membranes decrease steady-state concentrations of the AFR in a protein- and NADH-dependent manner. The AFR reductase has a high apparent affinity for both NADH and the AFR (< 2 microM). When measured in open ghosts, the reductase is comprised of an inner membrane activity (both substrate sites on the cytosolic membrane face) and a trans-membrane activity that mediates extracellular AFR reduction using intracellular NADH. However, the trans-membrane activity constitutes only about 12% of the total measured in ghosts. Ghost AFR reductase activity can also be differentiated from NADH-dependent ferricyanide reductase(s) by its sensitivity to the detergent Triton X-100 and insensitivity to enzymatic digestion with cathepsin D. This NADH-dependent AFR reductase could serve to recycle ascorbic acid at a crucial site on the inner face of the plasma membrane.

Functional geometry of the permeation pathway of Ca2+-activated Cl-channels inferred from analysis of voltage-dependent block

We examined the voltage-dependent block of Ca(2+)-activated Cl(-) channels by anthacene-9-carboxylic acid (A9C), diphenylamine-2-carboxylic acid (DPC), 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), and niflumic acid (NFA) in excised inside-out and outside-out patches from Xenopus oocytes. The fraction of the voltage field (delta) experienced by the blocking drug was determined from the voltage dependence of block. All the drugs blocked by entering the channel from the outside. delta was 0.6 for A9C, 0.3 for DPC and DIDS, and <0.1 for NFA. Because the voltage dependence of the drugs differed, the order of potency was also voltage-dependent. At +100 mV the order of potency was NFA > A9C > DIDS > DPC (K(i) (microm) = 10.1, 18.3, 48, and 111, respectively). Because the drugs are hydrophobic, they can cross the bilayer when applied from the inside and block the channel from the outside. The equilibrium geometries of the blockers were determined by molecular modeling and compared with their blocking positions (delta). This analysis suggests that the channel is an elliptical cone with the largest opening facing the extracellular space. The selectivity filter has an apparent size of 0.33 x 0.75 nm, because C(CN)(3)-, which has these dimensions, permeates. The external opening is at least 0.60 x 0.94 nm, because DPC has these dimensions and penetrates the channel approximately 30%.

Muscle-derived cell transplantation and differentiation into lower urinary tract smooth muscle

OBJECTIVES

To explore the feasibility of primary skeletal muscle-derived cell (MDC)-based tissue engineering and gene transfer into the lower urinary tract and to explore whether the injected primary skeletal MDCs can persist and differentiate into myotubes and myofibers in the bladder wall.

METHODS

Primary MDCs isolated from normal mice were first transduced with adenovirus encoding the expression of the beta-galactosidase reporter gene. Adult severe combined immunodeficiency mice (n = 12) were used in this study. The MDCs were injected into the right and left lateral bladder walls with a 10-microL Hamilton microsyringe. The amount of injected MDCs ranged from 1 to 1.5 x 10(6) cells. The tissue was harvested after 5, 35, and 70 days, sectioned, stained for fast myosin heavy chain, and assayed for beta-galactosidase expression.

RESULTS

We observed a large number of cells expressing beta-galactosidase in the bladder wall at each time point. Many myotubes and myofibers expressing beta-galactosidase and positively stained for fast myosin heavy chain were also seen in the bladder wall at 35 and 70 days after injection. Additionally, the size of the injected MDCs significantly increased during the course of the study (P <0.05).

CONCLUSIONS

We have demonstrated the long-term survival and beta-galactosidase expression of MDCs injected into the bladder wall. Moreover, our results suggest that some injected MDCs can differentiate into myofibers. These results suggest that MDCs can be a desirable substance for tissue engineering and an ex vivo method for gene transfer into the lower urinary tract.

Effects of simulated ischemia on spiral wave stability

Regional hyperkalemia during acute myocardial ischemia is a major factor promoting electrophysiological abnormalities leading to ventricular fibrillation (VF). However, steep action potential duration restitution, recently proposed to be a major determinant of VF, is typically decreased rather than increased by hyperkalemia and acute ischemia. To investigate this apparent contradiction, we simulated the effects of regional hyperkalemia and other ischemic components (anoxia and acidosis) on the stability of spiral wave reentry in simulated two-dimensional cardiac tissue by use of the Luo-Rudy ventricular action potential model. We found that the hyperkalemic "ischemic" area promotes wavebreak in the surrounding normal tissue by accelerating the rate of spiral wave reentry, even after the depolarized ischemic area itself has become unexcitable. Furthermore, wavebreak and fibrillation can be prevented if the dynamical instability of the normal tissue is reduced significantly by targeting electrical restitution properties, suggesting a novel therapeutic approach.

Coexistence of multiple spiral waves with independent frequencies in a heterogeneous excitable medium

We studied the interactions and coexistence of stable spiral waves with independent frequencies in a heterogeneous excitable medium, using numerical simulations of a spatial system based on the FitzHugh-Nagumo cell model. When the heterogeneity of the medium exceeded a critical value, a transition took place from a single dominant spiral wave to a coexistence of multiple spiral waves with independent frequencies and n:n-1 wave conduction blocks. In this case, multiple spiral waves could coexist because they are "insulated" from each other by chaotic regions.

Electrophysiological heterogeneity and stability of reentry in simulated cardiac tissue

Generation of wave break is a characteristic feature of cardiac fibrillation. In this study, we investigated how dynamic factors and fixed electrophysiological heterogeneity interact to promote wave break in simulated two-dimensional cardiac tissue, by using the Luo-Rudy (LR1) ventricular action potential model. The degree of dynamic instability of the action potential model was controlled by varying the maximal amplitude of the slow inward Ca(2+) current to produce spiral waves in homogeneous tissue that were either nearly stable, meandering, hypermeandering, or in breakup regimes. Fixed electrophysiological heterogeneity was modeled by randomly varying action potential duration over different spatial scales to create dispersion of refractoriness. We found that the degree of dispersion of refractoriness required to induce wave break decreased markedly as dynamic instability of the cardiac model increased. These findings suggest that reducing the dynamic instability of cardiac cells by interventions, such as decreasing the steepness of action potential duration restitution, may still have merit as an antifibrillatory strategy.

Impaired prostate tumorigenesis in Egr1-deficient mice

The transcription factor early growth response protein 1 (EGR1) is overexpressed in a majority of human prostate cancers and is implicated in the regulation of several genes important for prostate tumor progression. Here we have assessed the effect of Egr1 deficiency on tumor development in two transgenic mouse models of prostate cancer (CR2-T-Ag and TRAMP). Using a combination of high-resolution magnetic resonance imaging and histopathological and survival analyses, we show that tumor progression was significantly impaired in Egr1-/- mice. Tumor initiation and tumor growth rate were not affected by the lack of Egr1; however, Egr1 deficiency significantly delayed the progression from prostatic intra-epithelial neoplasia to invasive carcinoma. These results indicate a unique role for Egr1 in regulating the transition from localized, carcinoma in situ to invasive carcinoma.

Persistence and survival of autologous muscle derived cells versus bovine collagen as potential treatment of stress urinary incontinence

PURPOSE

We explored the use of autologous muscle derived cells as a method of treating stress urinary incontinence. We determined whether urethral muscle derived cell injection is feasible and compared it with bovine collagen injection.

MATERIALS AND METHODS

Muscle derived cells isolated from female Sprague-Dawley rats were first transduced with retrovirus carrying the transgene for beta-galactosidase. We injected approximately 1 to 1.5 x 106 cells into the bladder wall and proximal urethra of 6 autologous animals. Tissue was harvested after 3 and 30 days, sectioned, stained for fast myosin heavy chain and assayed for beta-galactosidase. To compare muscle derived cell and bovine collagen injections 100 microl. of commercially available bovine collagen were also injected in Sprague-Dawley female rats. Tissue was harvested in 3 animals each after 3 and 30 days, sectioned and stained for trichrome. Subsequently, 3 adult SCID mice were used to compare the level of transgene expression at each time point after injecting 1.5 x 106 cells per injection, which were transduced with adenovirus carrying the transgene for beta-galactosidase.

RESULTS

A large number of cells expressing beta-galactosidase were observed in the bladder and urethral wall 3 and 30 days after autologous cell injection in Sprague-Dawley rats. The persistence of primary muscle derived cells at 3 days was similar to that of collagen. However, at 30 days there was significant cell persistence while only a minimal amount of injected bovine collagen was detectable. Approximately 88% of the beta-galactosidase expression at day 3 remained at day 30 in SCID mice.

CONCLUSIONS

We present 2 new findings important for the emerging field of urological tissue engineering, including the feasibility of injecting autologous skeletal muscle derived cells into the lower urinary tract and the greater persistence of such injected cells versus injected bovine collagen. Therefore, autologous muscle derived cell injection may be an attractive alternative treatment option for stress urinary incontinence.

[Results of surgical treatment of 220 patients with lung cancer]

BACKGROUND

To explore the prognostic factors in the patients with lung cancer who were surgically treated.

METHODS

Two hundred and twenty patients with lung cancer were treated with surgical treatment. Of the whole group , exploratory operation was performed in 15 cases and radical resection was done in 205 cases (93. 2 %) .

RESULTS

The follow-up rate was 95. 8 %. The 1- , 5- , 10- and 20-year survival rate were 88. 3 %、45. 6 %、26. 2 % and 15. 4 % respectively. The prognosis of the patients was closely correlated with P-TNM stage , lymph node status and pathological classification ( P < 0. 01) , but not with extent of resection ( P > 0. 05) .

CONCLUSIONS

The prognosis of patients with lung cancer surgically treated is remarkably related to P-TNM stage , pathological classification and the mediastinal lymph node status.

Ventricular fibrillation: how do we stop the waves from breaking?

Combined experimental and theoretical developments have demonstrated that in addition to preexisting electrophysiological heterogeneities, cardiac electrical restitution properties contribute to breakup of reentrant wavefronts during cardiac fibrillation. Developing therapies that favorably alter electrical restitution properties have promise as a new paradigm for preventing fibrillation.

Gating of inward rectifier K+ channels by proton-mediated interactions of N- and C-terminal domains

Ion channels play an important role in cellular functions, and specific cellular activity can be produced by gating them. One important gating mechanism is produced by intra- or extracellular ligands. Although the ligand-mediated channel gating is an important cellular process, the relationship between ligand binding and channel gating is not well understood. It is possible that ligands are involved in the interactions of different protein domains of the channel leading to opening or closing. To test this hypothesis, we studied the gating of Kir2.3 (HIR) by intracellular protons. Our results showed that hypercapnia or intracellular acidification strongly inhibited these channels. This effect relied on both the N and C termini. The CO(2)/pH sensitivities were abolished or compromised when one of the intracellular termini was replaced. Using purified N- and C-terminal peptides, we found that the N and C termini bound to each other in vitro. Although their binding was weak at pH 7.4, stronger binding was seen at pH 6.6. Two short sequences in the N and C termini were found to be critical for the N/C-terminal interaction. Interestingly, there was no titratable residue in these motifs. To identify the potential protonation sites, we systematically mutated most histidine residues in the intracellular N and C termini. We found that mutations of several histidine residues in the C but not the N terminus had a major effect on channel sensitivities to CO(2) and pH(i). These results suggest that at acidic pH, protons appear to interact with the C-terminal histidine residues and present the C terminus to the N terminus. Consequentially, these two intracellular termini bound to each other through two short motifs and closed the channel. Thus, a novel mechanism for K(+) channel gating is demonstrated, which involves the N- and C-terminal interaction with protons as the mediator.

Mechanisms of discordant alternans and induction of reentry in simulated cardiac tissue

BACKGROUND

T-wave alternans, which is associated with the genesis of cardiac fibrillation, has recently been related to discordant action potential duration (APD) alternans. However, the cellular electrophysiological mechanisms responsible for discordant alternans are poorly understood.

METHODS AND RESULTS

We simulated a 2D sheet of cardiac tissue using phase 1 of the Luo-Rudy cardiac action potential model. A steep (slope >1) APD restitution curve promoted concordant APD alternans and T-wave alternans without QRS alternans. When pacing was from a single site, discordant APD alternans occurred only when the pacing rate was fast enough to engage conduction velocity (CV) restitution, producing both QRS and T-wave alternans. Tissue heterogeneity was not required for this effect. Discordant alternans markedly increases dispersion of refractoriness and increases the ability of a premature stimulus to cause localized wavebreak and induce reentry. In the absence of steep APD restitution and of CV restitution, sustained discordant alternans did not occur, but reentry could be induced if there was marked electrophysiological heterogeneity. Both discordant APD alternans and preexisting APD heterogeneity facilitate reentry by causing the waveback to propagate slowly.

CONCLUSION

Discordant alternans arises dynamically from APD and CV restitution properties and markedly increases dispersion of refractoriness. Preexisting and dynamically induced (via restitution) dispersion of refractoriness independently increase vulnerability to reentrant arrhythmias. Reduction of dynamically induced dispersion by appropriate alteration of electrical restitution has promise as an antiarrhythmic strategy.

Mechanisms of ventricular fibrillation induction by 60-Hz alternating current in isolated swine right ventricle

BACKGROUND

The mechanisms by which 60-Hz alternating current (AC) can induce ventricular fibrillation (VF) are unknown.

METHODS AND RESULTS

We studied 7 isolated perfused swine right ventricles in vitro. The action potential duration restitution curve was determined. Optical mapping techniques were used to determine the patterns of activation on the epicardium during 5-second 60-Hz AC stimulation (10 to 999 microA). AC captured the right ventricles at 100+/-65 microA, which is significantly lower than the direct current pacing threshold (0.77+/-0.45 mA, P:<0.05). AC induced ventricular tachycardia or VF at 477+/-266 microA, when the stimulated responses to AC had (1) short activation CLs (128+/-14 ms), (2) short diastolic intervals (16+/-9 ms), and (3) short diastolic intervals associated with a steep action potential duration restitution curve. Optical mapping studies showed that during rapid ventricular stimulation by AC, a wave front might encounter the refractory tail of an earlier wave front, resulting in the formation of a wave break and VF. Computer simulations reproduced these results.

CONCLUSIONS

AC at strengths less than the regular pacing threshold can capture the ventricle at fast rates. Accidental AC leak to the ventricles could precipitate VF and sudden death if AC results in a fast ventricular rate coupled with a steep restitution curve and a nonuniform recovery of excitability of the myocardium.

[Clinical results of transmyocardial laser revascularization for 77 patients with coronary artery disease]

OBJECTIVE

To analyses the clinical results of transmyocardial laser revascularization (TMLR) for 77 patients with coronary artery diseases (CAD).

METHODS

The mean age of the patients was (65 +/- 7) years. Previous medical record included CABG (6 patients), PTCA (9), AMI (66.2%), hypertension (70.1%), and diabetes mellitus (45.5%). TMLR was performed on the beating heart via a left anterolateral thoracotomy at the fifth intercostal space. Transesophageal echocardiography showed transmyocardial penetration of 23 +/- 6 channels.

RESULTS

The hospital mortality was 3.8%, and postoperative complications were AMI (3.8%), left ventricular failure (2.6%), PVC (5.2%). After operation, the mean CCS angina class was improved from the baseline 3.5 +/- 0.7 to 2.1 +/- 0.3 at 3 months, 1.7 +/- 0.3 at 6 months, 1.7 +/- 0.3 at 12 months and 1.8 +/- 0.4 at 24 months. One patient died of AMI and two died not due to cardiac events during a follow-up of 3 to approximately 24 months. Echocardiography showed that the average of left ventricular ejection fractions was improved significantly at 6 months after operation compared with the preoperative value (P = 0.0457). (201)TI-SPECT showed a remarkable improvement in reversible ischemia in 70% patients followed up. Metabolic stress test for 20 patients followed up patients demonstrated an average increase in exercise tolerance from 7.1 +/- 3.2 min at the baseline to 9.6 +/- 1.3 min at 12 months (P = 0.021). Similarly the METs increased from 4.3 +/- 2.1 at the baseline to 5.4 +/- 2.0 at 12 months.

CONCLUSIONS

TMLR is a safe and effective procedure for the treatment of end stage coronary artery diseases not amenable to PTCA or CABG. The effect of TMLR is associated with indication, correct evaluation of myocardial ischemia, and management for postoperative complications.