IPCS: an integrated process control system for enhanced in-situ bioremediation

To date, there has been little or no research related to process control of subsurface remediation systems. In this study, a framework to develop an integrated process control system for improving remediation efficiencies and reducing operating costs was proposed based on physical and numerical models, stepwise cluster analysis, non-linear optimization and artificial neural networks. Process control for enhanced in-situ bioremediation was accomplished through incorporating the developed forecasters and optimizers with methods of genetic algorithm and neural networks modeling. Application of the proposed approach to a bioremediation process in a pilot-scale system indicated that it was effective in dynamic optimization and real-time process control of the sophisticated bioremediation systems.

The role of pores in acellular dermal matrix substitute

To promote the engraftment rate of autologous skin combined with acellular dermal matrix (ADM), ADM was punched to produce regular pores from 500 to 800 µm in diameter, separated by a distance of 3 to 5 mm. The porous ADM was then implanted beneath the flap and transplanted onto an open full-thickness defect wound combined with autografts about 0.2 mm thick in a rat model. The change in diameter of pores in ADM and the neovascularization of ADM matrix were evaluated, and the take rate of porous ADM combined with overlying autologous skin was compared with that of non-porous ADM. The results showed that when porous ADM was grafted onto the full-thickness skin excised wound, plasma penetrated from the wound bed to the surface of ADM through these pores, i.e. the pores punched on ADM were responsible for the imbibition function. Subdermal implantation of ADM indicated that one week post-operation the pores in ADM were still detectable, and some of them contained red blood cells. Two to three weeks after grafting the pores became smaller, partly because of newly synthesized collagen matrix deposition. In Sprague-Dawley rats the engraftment rate of autologous sheet skin graft placed over ADM with pores was 89.5%, which was significantly higher than ADM without pores (63.2%). It is concluded that porous ADM could serve as a good dermal substitute.

An integrated numerical and physical modeling system for an enhanced in situ bioremediation process

Groundwater contamination due to releases of petroleum products is a major environmental concern in many urban districts and industrial zones. Over the past years, a few studies were undertaken to address in situ bioremediation processes coupled with contaminant transport in two- or three-dimensional domains. However, they were concentrated on natural attenuation processes for petroleum contaminants or enhanced in situ bioremediation processes in laboratory columns. In this study, an integrated numerical and physical modeling system is developed for simulating an enhanced in situ biodegradation (EISB) process coupled with three-dimensional multiphase multicomponent flow and transport simulation in a multi-dimensional pilot-scale physical model. The designed pilot-scale physical model is effective in tackling natural attenuation and EISB processes for site remediation. The simulation results demonstrate that the developed system is effective in modeling the EISB process, and can thus be used for investigating the effects of various uncertainties.

Role of cytosolic liver fatty acid binding protein in hepatocellular oxidative stress: effect of dexamethasone and clofibrate treatment

The presence of cysteine and methionine groups together with an ability to bind long-chain fatty acid (LCFA) oxidation products makes liver fatty acid binding protein (L-FABP) an attractive candidate against hepatocellular oxidative stress. In this report, we show that pharmacological treatment directed at modulating L-FABP level affected hepatocellular oxidant status. L-FABP expressing 1548-hepatoma cells, treated with dexamethasone or clofibrate, decreased and increased intracellular L-FABP levels, respectively. Oxidative stress was induced by H2O2 incubation or hypoxia-reoxygenation. The fluorescent marker, dichlorofluorescein (DCF), was employed to measure intracellular reactive oxygen species (ROS). Hepatocellular damage was assessed by lactate dehydrogenase (LDH) level. Dexamethasone treatment resulted in a significant increase in DCF fluorescence with higher LDH release compared to control cells. Clofibrate treatment, however, resulted in a significant decrease in both parameters (p<0.05). Drug treatments did not affect cytosolic activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), or catalase suggesting that the differences between treated and control cells may likely be associated with varying L-FABP levels. We conclude that L-FABP may act as an effective endogenous cytoprotectant against hepatocellular oxidative stress.

Systemic inhibition of tumor growth by soluble Flk-1 gene therapy combined with cisplatin

Soluble Flk-1, a soluble vascular endothelial growth factor (VEGF) receptor, is a potent inhibitor of angiogenesis, which could restrain growth and metastasis of some experimental tumors. However, antiangiogenic agents alone cannot eradicate tumor completely, and should be combined with other therapy to enhance their effects. In this study, we evaluated the antitumor activity of the combination therapy in the immunocompetent BALB/c mice bearing H22 hepatoma and Meth A fibrosarcoma, respectively. Mice were treated with either msFlk-1 i.m. at 100 microg/mouse once every 3 days for four times from day 3 after the tumor cell injection, cisplatin cycled twice (2 mg/kg i.p. on days 4 and 11 after the tumor cell inoculation), or both agents together. Tumor growth and survival time were continually observed. Antiangiogenesis in vivo was determined by CD31 immunohistochemistry. Assessment of apoptotic cells and histological analysis was also conducted in tumor tissues. Our results showed that the combination therapy could evidently improve antitumor efficacy, including tumor growth suppression, mice survival prolongation, tumor cell apoptosis augmentation as well as neovascularization inhibition as compared with controls, without serious adverse effects. Our data suggest that the combination of DDP with msFlk-1 is more effective to suppress tumor growth in mice than either agent alone, and this combination regimen showed its potential for future clinical application.

Transplantation of Composite Skin Containing Keratinocytes Cultured on a Fibroblast-conditioned Acellular Dermal Matrix

To evaluate the role of fibroblasts in composite skin reconstructed in vitro, four different types of composite skin (A, B, C, and D) were prepared. Human keratinocytes were seeded onto the epidermal side of an acellular dermal matrix (ADM) in type A. Keratinocytes were seeded onto the epidermal side of an ADM and human fibroblasts onto the dermal side in type B. Both keratinocytes and fibroblasts were seeded onto the epidermal side in type C. Type D consisted of fibroblasts on both sides of the ADM and keratinocytes on the epidermal side. The adherence of keratinocytes to the ADM was observed. The composite skin was then transplanted onto full-thickness skin defect wounds in nude mice. Results showed that the adherence of keratinocytes to the ADM was improved when fibroblasts were pre-seeded onto the epidermal side of the ADM. The composite skin was able to close full-thickness skin defect wounds. The take rates were respectively 44.1 ± 7.8%, 47.3 ± 5.4%, 75.2 ± 8.8%, and 81.2 ± 8.1% for types A, B, C, and D. The take rates of types C and D were significantly higher than those of types A and D. There was no significant difference in take rate between types C and D. In conclusion, composite skin consisting of keratinocytes cultured on a fibroblast-conditioned ADM was a good skin substitute.

Membrane binding proteins are the major determinants for the hepatocellular transmembrane flux of long-chain fatty acids bound to albumin

PURPOSE

The hepatic transmembrane flux of long-chain fatty acids (LCFA) occurs through passive and fatty acid transport protein facilitated processes from blood. The extent that these transport processes can be related to the unbound and protein-bound fractions of LCFA in blood is not clear.

METHODS

We used hepatocyte suspensions, hepatoma monolayers, and perfused rat livers to quantitate the transport of purified [(3)H]palmitate ([(3)H]PA) and 12-(N-methyl)-N-[(7-nitrobenz-2oxa-1,3-diazol-4yl-)amino]octadecanoicacid (12-NBDS) from solutions with a constant unbound LCFA concentration with varying bovine serum albumin (BSA) concentrations and in the presence and absence of antisera raised against cytosolic liver fatty acid binding protein (L-FABP).

RESULTS

In the absence of L-FABP antisera, using an unbound ligand concentration that was adjusted to remain constant at each BSA concentration, hepatocyte [(3)H]PA and 12-NBDS uptake rates increased linearly with an increase in BSA concentration (p < 0.0001). In the presence of L-FABP antisera, [(3)H]PA uptake showed a greater reduction in the presence of 100 muM BSA than 5 muM BSA. The calculated permeability surface area product (PS) confirmed that both unbound and bound fractions of LCFA contributed to the overall flux, but only the PS for the protein-bound fraction was reduced in the presence of L-FABP antisera. In situ rat liver perfusion studies showed that the only rate process for the disposition of [(3)H]PA in the liver inhibited by L-FABP antisera was that for influx, as defined by PS, and that it reduced PS in the perfused liver by 42%.

CONCLUSION

These results suggest that, at physiological albumin concentrations, most of the LCFA uptake is mediated from that bound to albumin by a hepatocyte basolateral membrane transport protein, and uptake of unbound LCFA occurring by passive diffusion contributes a minor component.

Risk factors for oesophageal squamous dysplasia in adult inhabitants of a high risk region of China

BACKGROUND

Oesophageal squamous cell carcinoma (OSCC) is a common cancer worldwide and has a very high mortality rate. Squamous dysplasia is the precursor lesion for OSCC and it can be seen during routine endoscopy with Lugol's iodine staining. We aimed to examine the risk factors for squamous dysplasia and determine if a risk model could be constructed which would be useful in selecting apparently healthy subjects for endoscopic screening in a high risk population in Linzhou, People's Republic of China.

SUBJECTS AND METHODS

In this cross sectional study, 724 adult volunteers aged 40-65 years were enrolled. All subjects completed a questionnaire regarding potential environmental exposures, received physical and dental examinations, and underwent upper endoscopy with Lugol's iodine staining and biopsy. Subjects were categorised as having or not having histologically proven squamous dysplasia/early cancer. Risk factors for dysplasia were examined using univariate and multivariate logistic regression. The utility of the final multivariate model as a screening tool was assessed using a receiver operating characteristics curve.

RESULTS

We found that 230 of 720 subjects (32%) with complete data had prevalent squamous dysplasia. In the final multivariate model, more household members (odds ratio (OR) 1.12/member (95% confidence interval (CI) 0.99, 1.25)), a family history of cancer (OR 1.57 (95% CI 1.13-2.18)), higher systolic blood pressure OR 1.11/10 mm Hg (95% CI 1.03-1.19)), heating the home without a chimney (OR 2.22 (95% CI 1.27-3.86)), and having lost more but not all of your teeth (OR 1.91 for 12-31 teeth lost (95% CI 1.17-3.15)) were associated with higher odds of having dysplasia. Higher household income (OR 0.96/100 RMB (95% CI 0.91-1.00)) was associated with a lower odds of having dysplasia. Although we found several statistically significant associations, the final model had little ability to accurately predict dysplasia status, with maximum simultaneous sensitivity and specificity values of 57% and 54%, respectively.

CONCLUSIONS

We found that risk factors for dysplasia were similar to those previously identified as risk factors for OSCC in this population. The final model did a poor job of identifying subjects who had squamous dysplasia. Other methods will need to be developed to triage individuals to endoscopy in this high risk population.

Assessing the cellular transmembrane electrical potential difference on the hepatic uptake of palmitate

Understanding the driving forces for the hepatic uptake of endogenous and exogenous substrates in isolated cells and organs is fundamental to describing the underlying hepatic physiology/pharmacology. In this study we investigated whether uptake of plasma protein-bound [3H]-palmitate across the hepatocyte wall is governed by the transmembrane electrical potential difference (PD). Uptake was studied in isolated hepatocytes and isolated perfused rat livers (IPL). Protein-binding and vasoactive properties of the different perfusates were determined using in vitro heptane/buffer partitioning studies and the multiple indicator dilution (MID) technique in the IPL, respectively. Altering hepatocyte PD by perfusate ion substitution resulted in either a substantial depolarization (-14 +/- 1 mV, n = 12, mean +/- S.E., substituting choline for Na+) or hyperpolarization (-46 +/- 3 mV, n = 12, mean +/- S.E., substituting nitrate for Cl-). Perfusate ion substitution also affected the equilibrium binding constant for the palmitate-albumin complex. IPL studies suggested that, other than with gluconate buffer, hepatic [3H]-palmitate extraction was not affected by the buffer used, implying PD was not a determinant of extraction. [3H]-Palmitate extraction was much lower (p < 0.05) when gluconate was substituted for Cl- ion. This work contrasts with that for the extraction of [3H]-alanine where hepatic extraction fraction was significantly reduced during depolarization. Changing the albumin concentration did not affect hepatocyte PD, and [3H]-palmitate clearance into isolated hepatocytes was not affected by the buffers used. MID studies with vascular and extravascular references revealed that, with the gluconate substituted buffer, the extravascular volume possibly increased the diffusional path length thus explaining reduced [3H]-palmitate extraction fraction in the IPL.

Histological precursors of oesophageal squamous cell carcinoma: results from a 13 year prospective follow up study in a high risk population

BACKGROUND

Oesophageal squamous cell carcinoma (OSCC) has a very poor prognosis, which is largely due to late diagnosis. Successful early detection strategies will require identification of clinically relevant precursor lesions that can be targets for screening and treatment.

AIMS

To identify the clinically relevant histological precursors of OSCC.

SUBJECTS

A cohort of 682 endoscoped patients from a high risk rural population in Linxian, China.

METHODS

Subjects were endoscoped and biopsied at baseline and followed for 13.5 years. We estimated the relative risk of developing OSCC for each of the initial histological diagnoses using Cox proportional hazards regression models.

RESULTS

A total of 114 (16.7%) patients developed OSCC during the follow up period. After adjusting for potential confounding factors, relative risks (95% confidence intervals) for incidence of this tumour, by initial histological diagnosis, were: normal 1.0 (reference), oesophagitis 0.8 (0.2-3.2), basal cell hyperplasia 1.9 (0.8-4.5), mild dysplasia 2.9 (1.6-5.2), moderate dysplasia 9.8 (5.3-18.3), severe dysplasia 28.3 (15.3-52.3), and carcinoma in situ 34.4 (16.6-71.4).

CONCLUSIONS

In this study, squamous dysplasia and carcinoma in situ were the only histological lesions associated with a significantly increased risk of developing OSCC within 13.5 years after endoscopy. There was no evidence that oesophagitis predisposed to this tumour. Increasing grades of dysplasia were strongly associated with increasing risk, indicating that the histological grading was clinically meaningful. The follow up experience of severe dysplasia and carcinoma in situ was equivalent, suggesting that this distinction is not clinically relevant. Documenting these precursor lesions of OSCC should assist in the development of effective prevention, early detection, and treatment strategies for this disease.

Differential involvement of Bax and Bak in TRAIL-mediated apoptosis of leukemic T cells

TRAIL-induced apoptosis has been considered a promising therapeutic approach for tumors that are resistant to chemotherapy, which is usually mediated via mitochondrial apoptotic cascades. Recent studies have shown that in certain cancer cells, TRAIL-mediated apoptosis is also dependent on mitochondrial involvement, suggesting that similar mechanisms of resistance to chemotherapy might be implicated in the resistance of tumor cells to TRAIL. We have used TRAIL-resistant leukemic cells that are deficient in both Bax and Bak to determine the roles of these Bcl-2 members in TRAIL-mediated apoptosis. Exposure of these cells to TRAIL did not have an impact on cell viability, although it induced the processing of caspase-3 to its active p20 subunit. The activity of the p20 caspase-3 appeared to be inhibited as no autoprocessing of this p20 subunit or cleavage of known caspase-3 substrates were detected. Also, in the absence of Bax and Bak, no release of mitochondrial apoptogenic proteins was observed following TRAIL treatment. Adenoviral transduction of the Bax, but not the Bak gene, to the Bax/Bak-deficient leukemic cells rendered them TRAIL-sensitive as assessed by enhanced apoptotic death and caspase-3 processing. These findings demonstrate preferential utilization of Bax over Bak in leukemic cell response to specific apoptotic stimulation.

Dynamic analysis of hepatitis B virus DNA and its antigens in 2.2.15 cells

The 2.2.15 cells-derived from HepG2 cells transfected with a plasmid containing hepatitis B virus (HBV) DNA secrete surface antigen (HBsAg) particles, nucleocapsids and virions (Proc Natl Acad Sci U S A 1987; 84: 1005-1009). The latter elicit acute hepatitis in chimpanzees (Proc Natl Acad Sci U S A 1987; 84: 4641-4644). We studied the presence of intracellular and extracellular HBV covalently closed circular (ccc) DNA in this culture system by polymerase chain reaction (PCR), kinetically analysed HBsAg and hepatitis B e antigen (HBeAg) released in the culture media by quantitative enzyme-linked immunosorbent assay and quantitated by real-time PCR but HBV DNA from intracellular and extracellular HBV-DNA. HBV cccDNA was found both intracellularly and extracellularly. A significant correlation was seen between the extracellular HBV DNA levels and virus antigens (r = 0.833; P = 0.01 and r = 0.939; P < 0.01 for HBsAg and HBeAg, respectively), whereas there was no statistical correlation between intracellular HBV DNA levels and virus antigen levels (r = 0.024; P = 0.955 and r = 0.177; P = 0.625 for HBsAg and HBeAg, respectively). These data would be valuable in studies of the HBV life cycle and of potential anti-viral agents.

Cladistic analysis of human apolipoprotein a4 polymorphisms in relation to quantitative plasma lipid risk factors of coronary heart disease

Genetic variation in several genes involved in lipid metabolism is known to affect population variation in quantitative lipid risk factor profiles for coronary heart disease (CHD). The apolipoprotein A-IV gene (APOA4) is one such candidate gene. We genotyped five polymorphisms in the APOA4 gene (codon 127, codon 130, codon347, codon 360 and 3' VNTR) and investigated their impact on plasma lipid trait levels in three populations comprising 604 U.S. non-Hispanic Whites (NHWs), 408 U.S. Hispanics and 708 Nigerian Blacks. Cladistic analysis was carried out to identify 5-site haplotypes that were associated with significant phenotypic differences in each population. The distribution of APOA4 genotypes was significantly different between ethnic groups. The Africans were monomorphic for two of the five sites (codons 130 and 360), but possess a unique 12 bp insertion that was not observed in NHWs and Hispanics. Due to linkage disequilibrium between the sites, only 6 haplotypes were observed in NHWs and Hispanics, and 4 in Africans. Several gender-and ethnic-specific associations between genotypes and plasma lipid traits were observed when single sites were used. Several haplotypes were identified by cladistic analysis that may carry functional mutations that affect plasma lipid trait levels.

Resistance to granzyme B-mediated cytochrome c release in Bak-deficient cells

Granzyme B (GrB), a serine protease with substrate specificity similar to the caspase family, is a major component of granule-mediated cytotoxicity of T lymphocytes. Although GrB can directly activate caspases, it induces apoptosis predominantly via Bid cleavage, mitochondrial outer membrane permeabilization, and cytochrome c release. To study the molecular regulators for GrB-mediated mitochondrial apoptotic events, we used a CTL-free cytotoxicity system, wherein target cells are treated with purified GrB and replication-deficient adenovirus (Ad). We report here that the Bcl-2 proapoptotic family member, Bak, plays a dominant role in GrB-mediated mitochondrial apoptotic events. A variant of Jurkat cells, deficient in Bak expression, was resistant to GrB/Ad-mediated apoptosis, as determined by lack of membranous phosphatidylserine exposure, lack of DNA breaks, lack of mitochondrial outer membrane permeabilization, and unchanged expression of inner mitochondrial membrane cardiolipin. The resistance of Bak-deficient cells to GrB/Ad cytotoxicity was reversed by transduction of the Bak gene into these cells. The requirement for both Bid and Bak, was further demonstrated in a cell-free system using purified mitochondria and S-100 cytosol. Purified mitochondria from Bid knockout mice, but not from Bax knockout mice, failed to release cytochrome c in response to autologous S-100 and GrB. Also, Bak-deficient mitochondria did not release cytochrome c in response to GrB-treated cytosol unless recombinant Bak protein was added. These results are the first to report a role for Bak in GrB-mediated mitochondrial apoptosis. This study demonstrates that GrB-cleaved Bid, which differs in size and site of cleavage from caspase-8-cleaved Bid, utilizes Bak for cytochrome c release, and therefore, suggests that deficiency in Bak may serve as a mechanism of immune evasion for tumor or viral infected cells.

Hepatocyte [3H]-palmitate uptake: effect of albumin surface charge modification

The role of plasma proteins on the cellular uptake of lipophilic substrates has perplexed investigators for many years. We tested the hypothesis that an ionic interaction between the protein-ligand complex and hepatocyte surface may be responsible for supplying more ligand to the cell for uptake. The surface-charged groups on albumin were modified to yield proteins having a range of isoelectric points (ALB, ALBs, ALBm, ALBe had values of 4.8-5.0, 4.5-4.7, 3.0-3.5, 8.4-8.6, respectively). [3H]-Palmitate uptake studies were performed with adult rat hepatocyte suspensions using similar unbound ligand fractions in the presence of the different binding proteins. Mass spectrometry, isoelectric focusing (pI), and heptane:water partitioning were used to determine protein molecular weight, pI, and protein-palmitate equilibrium binding constant, respectively. Hepatocyte [3H]-palmitate clearance in the presence of ALBs and ALBm were significantly lower (p < 0.05) than ALB, whereas [3H]-palmitate clearance in the presence of ALBe was significantly higher (p < 0.05) than ALB. The data were consistent with the notion that ionic interactions between extracellular protein-ligand complexes and the hepatocyte surface facilitate the uptake of long-chain fatty acids.

Hepatocyte [3H]-palmitate uptake: effect of albumin surface charge modification

The role of plasma proteins on the cellular uptake of lipophilic substrates has perplexed investigators for many years. We tested the hypothesis that an ionic interaction between the protein–ligand complex and hepatocyte surface may be responsible for supplying more ligand to the cell for uptake. The surface-charged groups on albumin were modified to yield proteins having a range of isoelectric points (ALB, ALBs, ALBm, ALBe had values of 4.8–5.0, 4.5–4.7, 3.0–3.5, 8.4–8.6, respectively). [3H]-Palmitate uptake studies were performed with adult rat hepatocyte suspensions using similar unbound ligand fractions in the presence of the different binding proteins. Mass spectrometry, isoelectric focusing (pI), and heptane : water partitioning were used to determine protein molecular weight, pI, and protein-palmitate equilibrium binding constant, respectively. Hepatocyte [3H]-palmitate clearance in the presence of ALBs and ALBm were significantly lower (p < 0.05) than ALB, whereas [3H]-palmitate clearance in the presence of ALBe was significantly higher (p < 0.05) than ALB. The data were consistent with the notion that ionic interactions between extracellular protein–ligand complexes and the hepatocyte surface facilitate the uptake of long-chain fatty acids.Key words: uptake, long-chain fatty acid, hepatic, protein, albumin, surface charge, facilitation, ionic interaction.

A role for mitochondrial Bak in apoptotic response to anticancer drugs

In the present study a clonal Jurkat cell line deficient in expression of Bak was used to analyze the role of Bak in cytochrome c release from mitochondria. The Bak-deficient T leukemic cells were resistant to apoptosis induced by UV, staurosporin, VP-16, bleomycin, or cisplatin. In contrast to wild type Jurkat cells, these Bak-deficient cells did not respond to UV or treatment with these anticancer drugs by membranous phosphatidylserine exposure, DNA breaks, activation of caspases, or release of mitochondrial cytochrome c. The block in the apoptotic cascade was in the mitochondrial mechanism for cytochrome c release because purified mitochondria from Bak-deficient cells failed to release cytochrome c or apoptosis-inducing factor in response to recombinant Bax or truncated Bid. The resistance of Bak-deficient cells to VP-16 was reversed by transduction of the Bak gene into these cells. Also, the cytochrome c releasing capability of the Bak-deficient mitochondria was restored by insertion of recombinant Bak protein into purified mitochondria. Following mitochondrial localization, low dose recombinant Bak restored the mitochondrial release of cytochrome c in response to Bax; at increased doses it induced cytochrome c release itself. The function of Bak is independent of Bid and Bax because recombinant Bak induced cytochrome c release from mitochondria purified from Bax(-/-), Bid(-/-), or Bid(-/-) Bax(-/-) mice. Together, our findings suggest that Bak plays a key role in the apoptotic machinery of cytochrome c release and thus in the chemoresistance of human T leukemic cells.

Palmitate uptake by neonatal rat myocytes and hepatocytes. Role of extracellular protein

The role of extracellular binding proteins in the rate of [3H]palmitate uptake by neonatal cardiac myocytes and hepatocytes was investigated using a model-independent approach. Binding proteins used in this study included alpha1-acid glycoprotein [isoelectric point (pI) approximately 2.7], conalbumin (pI approximately 6.4), lysozyme (pI approximately 11.0), albumin (pI approximately 4.9), and albumin which had been modified to yield proteins with pI values of 3.5, 4.7, 7.5 and 8.6. All uptake studies were conducted at similar unbound ligand fractions. There was a linear relationship between the rate of neonatal hepatocyte [3H]palmitate clearance and protein pI (r2 = 0.98). In contrast, there was an overall poor relationship between neonatal cardiac myocyte [3H]palmitate-clearance rate and protein pI (r2 = 0.48). However, the relationship improved when the data on [3H]palmitate-clearance were analyzed using only the modified albumins. The study indicates that an ionic interaction between extracellular proteins and the hepatocyte surface enhances the overall uptake of [3H]palmitate. This interaction may be limited to albumin for neonatal cardiac myocytes.

Cardiac apoptosis in burned rats with delayed fluid resuscitation

Clinical and experimental studies have shown that delayed fluid resuscitation postburn decreases heart function. We hypothesized that apoptosis occurs in the cardiomyocyte in this condition. To investigate this hypothesis, rats were burned, fluid resuscitation was delayed, and the integrity of cardiac genomic DNA in the burned rats was determined with an LM-PCR Ladder Assay kit. DNA fragmentation shown as DNA ladders on gels, the hallmark of apoptosis, was found in the heart tissue of these rats. In the early phase of delayed fluid resuscitation, the nuclear factor kappa B (NF-kappa B) was examined using an electrophoretic mobility shift assay and was found to be activated. In comparison with burned rats with immediate fluid resuscitation, nitric oxide levels in hearts from burned rats with delayed fluid resuscitation were significantly lower (P<0.01). These results suggest that apoptosis may be an important pathway for cardiac injury, which may result from the activation of NF-kappa B and decreased nitric oxide levels.

Tumor necrosis factor-alpha-promoted expression of Bcl-2 and inhibition of mitochondrial cytochrome c release mediate resistance of mature dendritic cells to melanoma-induced apoptosis

Melanoma escapes host defenses through a variety of means, including the elimination of immune effector cells within the tumor microenvironment. We have reported recently that murine and human tumors including melanoma induce premature apoptosis of dendritic cells both in vitro and in vivo. In this study, we have demonstrated that overexpression of the Bcl-2 protein family member Bcl-xL rescued murine dendritic cells (DCs) from melanoma-induced death in vitro. Another successful protection approach was tumor necrosis factor (TNF)-alpha-promoted sustained expression of the antiapoptotic protein Bcl-2 within dendritic cells. This effect of TNF-alpha was mediated by inhibition of mitochondrial cytochrome c release. Thus, both Bcl-xL and Bcl-2 enhance survival of dendritic cells within the tumor microenvironment. In addition, mature DCs were more resistant to melanoma-induced apoptosis than immature dendritic cells. This finding suggests a stage-dependent sensitivity of DCs to tumor-induced cell death. We conclude that: (a) mature DCs might be more suitable for the use of cancer vaccination; and (b) Bcl-2 protein family members such as Bcl-xL and Bcl-2 rescue DCs from tumor-induced premature apoptosis.

[1.4 kb 5' flanking region of class I patatin directs tuber-specific gus expression in potato (Solanum tuberosum L.)]

Binary vectors pPATIs (with partial signal sequence) and pPATI (without signal sequence) were constructed by fusing 1.4 kb 5' flanking regions of Class I patatin gene with GUS. Transient GUS expression was observed in in vitro tuber slices bombarded with pPATI. These constructs were then introduced into potato (cv. Desiree) via Agrobacterium tumefaciens transformation. Transgenic potato plants were confirmed by X-Gluc staining and PCR. Using in vitro tuberization system, GUS activities were assayed by fluorescence. It was shown that, in plants transformed with PATI-GUS, GUS specific activities were about 10-20 fold higher in tubers than in stems. Increased sucrose concentration could not induce PATI-GUS expression, but light enhanced PATI-GUS expression in cultured shoots.

Apoptosis-resistant mitochondria in T cells selected for resistance to Fas signaling

Jurkat leukemic T cells are highly sensitive to the extrinsic pathways of apoptosis induced via the death receptor Fas or tumor necrosis factor-related apoptosis-inducing ligand as well as to the intrinsic/mitochondrial pathways of death induced by VP-16 or staurosporin. We report here that clonal Jurkat cell lines selected for resistance to Fas-induced apoptosis were cross-resistant to VP-16 or staurosporin. Each of the apoptotic pathways was blocked at an apical phase, where common regulators of apoptosis have not yet been defined. The Fas pathway was blocked at the level of caspase-8, whereas the intrinsic pathway was blocked at the mitochondria. No processing or activity of caspases was detected in resistant cells in response to either Fas-cross-linking or VP-16 treatment. Also, no apoptosis-associated alterations in the mitochondrial inner membrane, outer membrane, or matrix were detected in resistant Jurkat cells treated with VP-16. Thus, no changes in permeability transition, loss in inner membrane cardiolipin, generation of reactive oxygen species, or release of cytochrome c were observed in resistant cells treated with VP-16. Further, unlike purified mitochondria from wild type cells, those obtained from resistant cells did not release cytochrome c or apoptosis-inducing factor in response to recombinant Bax or truncated Bid. These results identify a defect in mitochondria ability to release intermembrane proteins in response to Bid or Bax as a mechanism of resistance to chemotherapeuetic drugs. Further, the selection of VP-16-resistant mitochondria via elimination of Fas-susceptible cells may suggest the existence of a shared regulatory component between the extrinsic and intrinsic pathways of apoptosis.

[30-year experiences on early detection and treatment of esophageal cancer in high risk areas]

The author had conducted the clinical study on early diagnosis and early therapy of esophageal cancer (EC) in the area of high prevalence for more than 30 years. In the endoscopic survey, 742 patients were diagnosed as early EC from 22,285 participants. The endoscopic appearance of the mucosa in early EC was classified into three types: (1) change of mucosa color: red and white area; (2) Increased thickness and change of the vascular pattern of the mucosa; (3) mucosa morphology: erosion, plaque, coarseness and nodular. Iodine staining under endoscopic examination had promoted the early detection of EC and precancerous lesions. Since 307 patients with EC at early stage (65 carcinoma in situ, 95 intramucosal carcinoma, and 147 submucosal carcinoma) had undergone esophagectomy. There were no lymphatic metastasis in carcinoma in situ, however there were 2 cases (2.11%) of intramucosal carcinoma and 27 cases (18.37%) of submucosal carcinoma with lymph node metastasis. 24-year follow-up, results showed that 5-year survival rate is 84.1% and a 10-year survival rate is 72.9% among the cases of esophagectomy. A 5-year survival rate is 100% in 22 cases followed up for full five years among 141 cases with endoscopic mucosectomy. According to this study, severe dysplasia and some moderate dysplasia were precancerous lesions. Should these precancerous cases be treated, the cancerization risk of target population would reduce dramatically and the incidence of EC would be decreased down to 2/3.

Tumor-induced apoptosis of T cells: amplification by a mitochondrial cascade

We have recently reported that apoptosis of T cells induced by squamous cell carcinoma of the head and neck (SCCHN) is partly Fas dependent. This tumor-induced T-cell death is mediated by the activities of caspase-8 and caspase-3 and is partially inhibited by antibodies to either Fas or Fas ligand. We report here that in contrast to apoptosis induced by agonistic anti-Fas antibody (Ab), the tumor-induced apoptotic cascade in Jurkat cells is significantly amplified by a mitochondrial loop. The involvement of mitochondria in tumor-induced apoptosis of T cells was demonstrated by changes in mitochondrial permeability transition as assessed by 3,3'-dihexiloxadicarbocyanine staining, by cleavage of cytosolic BID and its translocation to the mitochondria, by release of cytochrome c to the cytosol, and by the presence of active subunits of caspase-9 in Jurkat T cells cocultured with tumor cells. To further elucidate the significance of mitochondria in tumor-induced T-cell death, we investigated the effects of various inhibitors of the mitochondrial pathway. Specific antioxidants, as well as two inhibitors of mitochondria permeability transition, bongkrekic acid and cyclosporin A, significantly blocked the DNA degradation induced in Jurkat T cells by SCCHN cells. However, these inhibitors had no effect on cells triggered by anti-Fas Ab. Furthermore, a cell-permeable inhibitor of caspase-9, Ac-LEHD.CHO, which did not inhibit T-cell apoptosis induced by anti-Fas Ab, markedly inhibited apoptosis induced by etoposide or by coculture of Jurkat with SCCHN cells. These findings demonstrate that apoptotic cascades induced in Jurkat T lymphocytes by anti-Fas Ab or tumor cells are differentially susceptible to a panel of inhibitors of mitochondrial apoptotic events. It appears that besides the Fas-mediated pathway, additional mitochondria-dependent cascades are involved in apoptosis of tumor-associated lymphocytes. Inhibition of mitochondria-dependent cascades of caspase activation should be considered to enhance the success of immunotherapy or vaccination protocols in cancer.

Impact of genetic polymorphisms in cytochrome P450 2E1 and glutathione S-transferases M1, T1, and P1 on susceptibility to esophageal cancer among high-risk individuals in China

Esophageal cancer, which is prevalent in China, is believed to be induced by environmental carcinogens such as nitrosamines and other agents. The disproportionate geographical distribution of this cancer among individuals suggests a role for gene-environment interactions in developing the disease. We have shown in our preliminary study that a genetic polymorphism in cytochrome P450 2E1 (CYP2E1) that is known to activate nitrosamines may be a susceptibility factor involved in the early events leading to the development of esophageal cancer (Lin et al., Cancer Epidemiol. Biomark. Prev., 7: 1013-1018, 1998). This relatively larger study was conducted to compare the results with our previous findings. One hundred and fifty cases with esophageal cancer, 146 cases with esophageal dysplasia, and 150 normal controls were residents of Linxian, China, a high-risk area. Genomic DNA samples were assayed for restriction fragment length polymorphisms in the CYP2E1 and GSTP1 loci by PCR amplification followed by digestion with RsaI and Alw26I, respectively. Deletion of the GSTM1 and GSTT1 genes was detected by multiplex PCR. The distribution of CYP2E1 c1/c1 allele frequency was found to be significantly different between controls (44.0%) and cases with cancer (71.3%) or cases with dysplasia (70.6%; P < 0.0001). Individuals having the c1/c1 genotype were at a 3.1-fold [95% confidence interval (CI), 2.4-3.9] increased risk of developing dysplasia and a 3.2-fold (95% CI, 2.5-4.1) increased risk of developing squamous cell carcinoma of the esophagus. Although polymorphisms in the GSTT1 and GSTP1 were not significantly different between cases with cancer or cases with dysplasia and controls, the frequency of the GSTM1 non-null (+/+ and +/0) genotypes appeared to be overrepresented in cases with cancer compared with controls (odds ratio, 2.3; 95% CI, 1.8-3.0). Furthermore, a joint effect of the CYP2E1 c1/c1 genotype and GSTM1 non-null genotype on the cancer risk was observed, showing an odds ratio of 8.5 (95% CI, 3.7-19.9). These results demonstrate that CYP2E1 and perhaps GSTM1 are genetic determinants in the development of squamous cell carcinoma of the esophagus.