Simulation on long-term operation of an anaerobic bioreactor for Korean food wastes

A mathematical model was formulated to simulate the long-term performance of an anaerobic bioreactor designed to digest Korean food wastes. The system variables of various decomposition steps were built into the model, which predicts the temporal characters of solid waste, and volatile fatty acid (VFA) in the reactor, and gas production in response to various input loadings and temperatures. The predicted values of VFA and gas production were found to be in good agreement with experimental observations in batch and repeated-input systems. Finally, long-term reactor performance was simulated with respect to the seasonal temperature changes from 5°C in winter to 25°C in summer at different food waste input loadings. The simulation results provided us with information concerning the success or failure of a process during long-term operation.     

A reduction factor in goodness-of-fit and independence tests for clustered and weighted observations

Situations often arise in a large-scale household survey where a complex probability sample of clusters rather than of individuals is drawn from a large population. Typically, the clusters of such complex samples include a number of correlated members. The responses of these members are then weighted to obtain estimates for the population. Such weighted data are commonly published by the National Center for Health Statistics and other U.S. federal agencies. Frequently, problems arise when such data are tested by usual chi-square test statistics for goodness of fit or independence. Researchers have discovered that the usual chi-square tests provide spuriously inflated results when applied to cluster samples and that new methods are required to correct such problems. This paper proposes a strategy for a goodness-of-fit or independence test based on correlated and weighted data arising in cluster samples, and provides a factor that validly reduces the inflation of the usual chi-square statistics. This method is applied to the chronic condition data collected from the St Paul-Minneapolis, Minnesota, primary sampling unit (PSU) during the 1975 National Health Interview Survey (NHIS). This analysis, together with simulation studies presented elsewhere, provides evidence that the usual chi-square statistics from such data can be corrected for the impacts of clustering and weighting by use of the proposed reduction factor.     

Overexpression of BCL2 blocks TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human lung cancer cells

The tumor necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL or Apo2L) and its receptors are members of the tumor necrosis factor superfamily. TRAIL triggers apoptosis by binding to its two proapoptotic receptors DR4 and DR5, a process which is negatively regulated by binding of TRAIL to its two decoy receptors TRID and TRUNDD. Here, we show that TRAIL effectively induces apoptosis in H460 human non-small-cell lung carcinoma cells via cleavage of caspases 8, 9, 7, 3, and BID, release of cytochrome c from the mitochondria, and cleavage of poly (ADP-ribose) polymerase (PARP). However, overexpression of Bcl2 blocked TRAIL-induced apoptosis in H460 cells, which correlated with the Bcl2 protein levels. Importantly, the release of cytochrome c and cleavage of caspase 7 triggered by TRAIL were considerably blocked in Bcl2 overexpressing cells as compared to vector control cells. Moreover, inhibition of TRAIL-mediated cytochrome c release and caspase 7 activation by Bcl2 correlated with the inability of PARP to be cleaved and the inability of the Bcl2 transfectants to undergo apoptosis. Thus, these results suggest that Bcl2 can serve an anti-apoptotic function during TRAIL-dependent apoptosis by inhibiting the release of cytochrome c and activation of caspase 7, thereby blocking caspase 7-dependent cleavage of cellular substrates.     

Nitric oxide as a bioregulator of apoptosis

Nitric oxide (NO), synthesized from l-arginine by NO synthases, is a small, diffusible, highly reactive molecule with dichotomous regulatory roles under physiological and pathological conditions. NO can promote apoptosis (proapoptosis) in some cells, whereas it inhibits apoptosis (antiapoptosis) in other cells. This complexity is a consequence of the rate of NO production and the interaction with biological molecules such as iron, thiols, proteins, and reactive oxygen species. Long-lasting production of NO acts as a proapoptotic modulator by activating caspase family proteases through the release of mitochondrial cytochrome c into the cytosol, upregulation of p53 expression, activation of JNK/SAPK, and altering the expression of apoptosis-associated proteins including Bcl-2 family proteins. However, low or physiological concentrations of NO prevent cells from apoptosis induced by trophic factor withdrawal, Fas, TNFalpha, and lipopolysaccharide. The antiapoptotic mechanism can be understood via expression of protective genes such as heat shock proteins, Bcl-2 as well as direct inhibition of the apoptotic caspase family proteases by S-nitrosylation of the cysteine thiol. Our current understanding of the mechanisms by which NO exerts both pro- and antiapoptotic actions is discussed in this review article.     

Development of a novel expression vector system using Spodoptera exigua nucleopolyhedrovirus

To develop a novel Spodoptera exigua nucleopolyhedrovirus (SeNPV) expression vector system, we examined characteristics of the SeNPV polyhedrin expression in S. exigua cells (Se301). While the extracellular virus titer of SeNPV was 100-fold lower than that of Autographa californica nucleopolyhedrovirus (AcNPV), the levels of polyhedral inclusion body (PIB) formation and polyhedrin expression were higher in SeNPV. To investigate foreign gene expression under the control of the polyhedrin promoter, polyhedrin-based transfer vector pSeKSK2 was constructed, and then recombinant virus SeK1-LacZ was constructed by inserting E. coli lacZ gene as a reporter gene into a genomic DNA of SeNPV using this transfer vector. The beta-Galactosidase activity of SeK1-LacZ in Se301 was about 1.3 times higher than that of BacPAK6. Thus, the SeNPV expression vector system constructed in this study would be very useful in the expression of foreign proteins, specifically for the enhancement of the pesticidal properties of SeNPV by inserting pesticidal genes.     

Purification and characterization of a novel dipeptidyl peptidase from Dictyostelium discoideum

A dipeptidyl peptidase (DPP) was purified to homogeneity using lys-ala-beta-naphthylamide, the standard substrate for DPP II. The enzyme is a monomer with a Mr of 70kDa, pl 5.2, and Km 5.0 microM. Its terminal amino acid sequence was XXLLYAIQKRLF and was not identical to that of any known protein. Although initially considered to be a DPP II, the enzyme differed in some properties from classical DPP IIs. It had a pH optimum of 7.9, was not active on X-pro-naphthylamides, the usual substrates of mammalian DPP II, but was active on arg-arg- and asp-arg-naphthylamides, substrates acted on by the DPP III class of enzymes. This enzyme therefore combines properties typical of both DPP II and III and differs from all previously described DPPs. Activity on lys-ala-beta-naphthylamide was most abundant during aggregation and its activity is consistent with processing specific peptides during development.     

β-adrenergic receptor desensitization in cardiac hypertrophy and heart failure

Conclusion Based on our recent data (37,54,56) and the association that profound alterations in βAR signaling are found in chronic end-stage human heart failure (64), it is possible that defects in this pathway are primary elements that underlie the transition from compensated to decompensated cardiac failure. Decreasing the level of myocardial βARK1 in established heart failure, is a novel approach to improving impaired βAR receptor function and potentially alter the pathogenesis in this disease.     

Involvement of protein kinase C and rho GTPase in the nuclear signalling pathway by transforming growth factor-beta1 in rat-2 fibroblast cells

The transforming growth factor (TGF)-beta signal-transduction cascade from the cell membrane to the nuclear target is poorly characterised. Here we report that treatment with TGF-beta1 induces the levels of endogenous c-fos mRNA in Rat-2 fibroblast cells. In addition, by transient transfection analysis, TGF-beta1 was shown to stimulate c-fos serum response element (SRE)-driven reporter gene activity in a dose- and time-dependent manner, suggesting that SRE is one of the nuclear targets of TGF-beta1. To understand the signalling cascade by which TGF-beta1 mediates the transactivation of c-fos SRE, cells were either pre-treated with various inhibitors or co-transfected with expression plasmids encoding inhibitory proteins for Rho GTPase together with the SRE-luciferase reporter gene. Our results showed that an inhibition of protein kinase C (PKC) or RhoA selectively repressed the stimulation of c-fos SRE by TGF-beta1, implying the possible roles of PKC and RhoA GTPase in TGF-beta1-induced signalling to c-fos SRE.