Search

We studied various liquids using a vertical attenuated total reflection (ATR) liquid sampling assembly in conjunction with Infrared Variable Angle Spectroscopic Ellipsometry (IR-VASE), to determine the infrared optical constants of several bulk liquids related to chemical warfare. The index of refraction, n, and the extinction coefficient, k, of isopropyl methylphosphonofluoridate (Sarin or GB), isopropyl alcohol (IPA) (a precursor of GB), and dimethyl methylphosphonate (DMMP)-a commonly employed simulant for GB, measured by our vertical ATR IR-VASE setup are closely matched to those found in other studies. We also report the optical constants of cyclohexyl methylphosphonofluoridate (GF), 2-(diisopropylamino)ethyl methylphosphonothioate (VX), bis-(2-chloroethyl) sulfide (HD), and 2-chlorovinyl dichloroarsine (L, Lewisite). The ATR IR-VASE technique affords an accurate measurement of the optical constants of these hazardous compounds.

Long-term ulcerative colitis (UC) patients are at increased risk for developing colorectal cancer. In order to develop strategies for preventing UC-associated carcinogenesis, we studied the effect of the antioxidant N-acetylcysteine (NAC) on UC-associated cancer development in a mouse model. Female C57BL/6J mice were subjected to long-term administration of dextran sulfate sodium (DSS) in the drinking fluid and 2-fold iron-enriched AIN76A diet, with or without NAC. In the DSS-plus-2-fold iron positive control group, gross tumor incidence was 88.5% (23/26 mice) after 12 DSS cycles (1 DSS cycle = 7 day DSS treatment period followed by 10 day recovery period). The tumor multiplicity was 2.1 ± 0.2 tumors/tumor-bearing mouse, and the tumor volume was 0.054 ± 0.019 cm³. With 0.2% NAC administration, tumor incidence was significantly reduced (68%, 17/25 mice; P < 0.05), as was the tumor multiplicity (1.5 ± 0.1 tumors/tumor-bearing mouse; P < 0.05). The tumor volume was lower (0.014 ± 0.004 cm³), but not significantly decreased. The proliferation index was significantly decreased in non-cancerous epithelia (48.5 ± 6.0% vs 32.0 ± 3.7%; P < 0.05), but not in tumor cells. NAC significantly induced apoptosis in both non-cancerous epithelia and colorectal adenocarcinoma. The number of cells immunostained-positive for nitrotyrosine was markedly decreased in the non-cancerous mucosa of NAC-treated mice (102.4 ±16.6 positive cells/mm² mucosa vs 53.6 ± 14.9 cells/mm²; P < 0.05). In addition, the number of inducible nitric oxide synthase (iNOS)-positive inflammatory cells in the non-cancerous mucosa of the distal colon was markedly decreased by NAC. This study indicates that the antioxidant NAC has the potential to serve as a preventive agent for UC-associated colorectal cancer, possibly via inhibition of cellular proliferation and nitrosative stress-caused cellular damage.

The aim of this study is to establish a good animal model for esophageal adenocarcinoma (EAC) and to test the hypothesis that iron over-nutrition enhances EAC formation. With rats, esophagogastroduodenal anastomosis (EGDA) was accomplished by anastomosing the duodenum to the gastroesophageal junction. Iron supplementation was given by i.p. injection of iron dextran (4 mg Fe/kg/week). This model mimics the development of human EAC by introducing mixed reflux of gastric and duodenal contents. At 40 weeks after surgery, the body weight, food intake, hemoglobin, total serum iron, transferrin saturation, serum albumin, and plasma levels of α-tocopherol, γ-tocopherol and retinol of the EGDA rats were not significantly different from those of the non-operated controls. The animals generally had only mild esophagitis, except that the area surrounding the anastomosis opening had more severe esophagitis. Columnar-lined esophagus (CLE), CLE with dysplasia, and EAC were diagnosed in 53.5, 34.9 and 25.6%, respectively, of the 43 rats. Intraperitoneal iron supplementation significantly enhanced esophageal lesions with CLE, CLE with dysplasia, and EAC to 78.0, 53.7 and 53.7%, respectively, of the 41 rats. All the tumors were well-differentiated mucinous adenocarcinomas at the squamocolumnar junction area, where most iron deposition was observed. EGDA avoids nutritional problems seen in other animal models for EAC. We believe that direct anastomosis of squamous epithelium to columnar epithelium and mixed reflux of gastric and duodenal contents lead to the formation of CLE and EAC. With this model, we demonstrated that iron supplementation significantly enhanced EAC formation, suggesting that iron over-nutrition could also be a risk factor for human EAC.

Previous work in our laboratory demonstrated that cytochrome P450 2B1 in rat liver was induced, but P450 2E1 was inhibited and inactivated, by diallyl sulfide (DAS), a compound derived from garlic. Such a selective effect on P450 enzymes is of considerable interest toward the understanding of dietary effects on xenobiotic metabolism. In the present study, the mechanism of P450 2B1 induction by DAS was investigated. Following a single dose of DAS (200 mg/kg body weight, ig), liver microsomal pentoxyresorufin dealkylase (PORd) activity, a representative activity of P450 2B1, was induced 3-, 16-, 26-, and 43-fold at 6, 12, 18, and 24 h after the treatment, respectively. A corresponding increase in the level of P450 2B 1/2 protein was observed by immunoblot analysis. The level of P450 2B1/2 mRNA in rat liver also increased markedly, reaching a maximum at 12 h after the DAS treatment. Hybridization with the isozyme-specific oligonucleotide probes revealed that the mRNA levels of both P450s 2B1 and 2B2 were induced. In contrast, the level of P450 2E1 mRNA in the liver of DAS-treated rats was not changed. The results of nuclear run-on assay revealed that the transcriptional rate of P450 2B1/2 genes in the rat liver increased 13-fold at 6 h after DAS administration and returned to the control value at 24 h. The transcription of P450 2B1/2 genes was blocked completely by α-amanitin, an inhibitor of RNA polymerase II. These results clearly demonstrate that the induction of P450 2B1/2 in rat liver by DAS is mainly due to transcriptional activation. In the DAS-treated rats, P450 2B1/2 mRNA was also markedly induced in the stomach and duodenum. The maximal induction was found at 12 h after the treatment while the levels of P450 2B1/2 mRNA increased 66-fold in the duodenum and 23-fold in the stomach. DAS treatment, however, did not change the levels of P450 2B1/2 mRNA in the lung and nasal mucosa.Copyright 1993, 1999 Academic Press

Cytochrome P450 2E1 (P450 2E1) catalyzes the biotransformation of many low-molecular-weight compounds including industrial solvents, indoor pollutants, alcohol, and drugs. In order to understand the nature of the P450 2E1 active site, we studied the competitive inhibition of the P450 2E1-catalyzed N-nitrosodimethylamine demethylation by alcohols and carboxylic acids with different alkyl chain lengths. Using microsomes from acetone-treated rats as the enzyme source of P450 2E1, the K_i value for each compound was measured. With primary alcohols and secondary alcohols, the K_i decreased with the increase in the carbon chain length until the carbon number reached 6 or 7; the free energy increment of binding was 0.28 kcal/mol CH₂ group. Similar inhibitory effects were also observed with human P450 2E1 heterologously expressed in Hep G2 cells. These results suggest that both rat and human P450 2E1 contain a pocket with hydrophobicity that serves as a binding site for low-molecular-weight substrates. Among a series of carboxylic acids and ω-hydroxycarboxylic acids investigated, dodecanoic acid was the strongest inhibitor (K_i = 22 µM), and 12-hydroxydodecanoic acid had the lowest K_i (320 µM) within the series of ω-hydroxycarboxylic acids. The free energy increment of binding for carboxylic acids was 0.35 kcal/mol CH2 group. 1,10-Decanedicarboxylic acid, which contains a carboxylic group at each end, showed a K_i > 20 mM. We suggest that for optimal interaction of a carboxylic acid moiety with the active site of P450 2E1, the hydrocarbon end of the molecule binds to the substrate binding site, leaving the carboxylic acid group outside of a proposed substrate access channel. The length of optimal substrates such as dodecanoic acid may reflect the length of the substrate access channel and the size of the active site. We estimate that the distance from the opening of the access channel to the oxygenation site is about 15 Å. Based on the structural features of P450 2E1 substrates and competitive inhibitors, we propose a conceptual model to illustrate the binding of these molecules in the active site of P450 2E1.Copyright 1995, 1999 Academic Press, Inc.

Benzene metabolism was investigated using two purified rat hepatic MFO systems containing either cytochrome P450 2B1 or cytoebrome P450 2E1. Studies performed over a wide substrate concentration range indicate that cytochrome P450 2B1 represents a relatively low-affinity form of cytochrome P450 with respect to benzene metabolism while cytochrome P450 2E1 is substantially more efficient at low benzene concentrations (apparent K_m value 0.17 mM). Cytochrome b₅ stimulated benzene metabolism by both cytochromes P450 2B1 and P450 2E1. With cytochrome P450 2E1 the stimulation of benzene metabolism by cytochrome b₅ was very pronounced (up to 6-fold) at low concentrations of benzene and was most effective (up to 15-fold) with respect to formation of hydroquinone. The metabolites observed in these studies were phenol and hydroquinone. Cytochrome P450 2E1 metabolized phenol with an affinity and capacity comparable to those of benzene. Hydroquinone was the major product formed at all substrate concentrations, while some catechol was formed at higher concentrations of phenol. Phenol metabolism was also stimulated by cytochrome b₅. The metabolism of benzene by cytochrome P450 2E1 in the presence of the major microsomal epoxide hydrolase, mEH_b, yielded phenol, hydroquinone, and benzene dihydrodiol. Interestingly, the addition of mEH_b did not lead to a decrease of the toxicologically important metabolite hydroquinone as might be expected from sequestration of the intermediate benzene oxide to the vicinal dihydrodiol pathway but rather led to a marked (more than 4-fold) increase in the formation of hydroquinone, suggesting catalysis by mEH_b of a predominant attack at the homoallylic position rather than at a carbon atom which forms the epoxide ring of benzene oxide. The addition of glutathione transferases plus glutathione did not yield GSH conjugates during benzene metabolism. However, metabolism of phenol by cytochrome P450 2E1 in the presence of glutathione yielded a nonenzymatically formed glutathione conjugate derived from hydroquinone or from an oxidative product of hydroquinone.Copyright 1993, 1999 Academic Press

Introduction Hemodialysis therapy and the aging process bave been reported to interfere with the trace element (TE) status in the body. This multicenter collaborative study on blood levels of TE in geriatric hemodialysis (HD) patients was carried out with an aim to clarify the impact of the aging process and HD therapy on the TE status in such patients.Methods One hundred and fifty-one HD patients (65 male, 86 female), all aged over 60 (68.2±3.86 y), and 112 elderly controls (58 male, 54 female) with a mean age of 67.5±3.03 were enrolled. All patients underwent standard HD for at least 6 months. The artificial kidneys used were hollow-fiber dialyzers of cellulose membranes. Water used for HD was prepared by reverse osmosis. Blood was collected in the morning prior to dialysis and after fasting. Atomic absorption spectrophotometry was applied to measure blood levels of Pb, Cd and Hg as well as plasma levels of Cu, Zn and Al. Data are presented as mean ± SEM. Student's t-test and linear regression were applied for statistics.Results Our geriatric chronic HD patients showed a marked elevation of blood Al and decreased plasma Zn concentrations. The blood levels of Cu, Cd, Pb and Hg were within normal limits. The blood concentrations of Al, Cu and Pb were significantly higher in HD patients than in the normal elderly controls, whereas Cd and Hg were similar in both groups, and Zn were lower in HD patients. Plasma Zn value decreased as dialysis duration increased, however there was a reversely linear correlation between plasma Zn and age.Conclusions This data reported can be regarded as a starting point and may serve as an insight to further studies on TE imbalances in geriatric and chronic HD populations.

Distributed memory multiprocessor (DMMP)systems have gained much attention because their performance can be easily scaled up by increasing the number of processor-memory modules. The k-ary n-cubeis the most popular interconnection network topology currently used in DMMPs. Wormhole routingis one of the most promising switching technology and has been used in many new generation multicomputers. Wormhole routing makes the communication latencyinsensitive to the network diameterand reduces the size of the channel buffer of each router. The concept of virtual channelsand virtual networksare widely invented for deadlock-freedesign. A fully adaptive wormhole routing method for k-ary n-cubes has been proposed by Linder in 1991 [10]. Unfortunately, the need of 2n− 1virtual networks makes it unreasonable. In this paper, we propose a virtual network system to support an adaptive, minimal and deadlock free routing in k-ary n-cubes. It uses only four virtual networks but can get a higher degree of adaptability and higher traffic capacity. Simulation results are presented to verify the performance.

The objective of this study is to elucidate the role of cytochrome P450 2E1 in the metabolic activation of acetaminophen (APAP) in mouse kidneys. With the kidney microsomes from C3H/HeJ mice, a significant sex-related difference was observed in the NADPH-dependent formation of a reactive APAP metabolite which was trapped as a glutathione conjugate. The enzyme activity in male mouse kidney was about 35- and 50-fold higher than that in the females at substrate concentrations 50 and 500 μM, respectively, and treatment of female mice with testosterone significantly induced the enzyme activity in the mouse kidney. No sex-related difference in this enzyme activity, however, was observed in the livers. The oxidative metabolism of APAP in control male mouse kidney microsomes displayed an apparent low Kmof 43-45 μM and an apparent high Kmof 603-702 μM. Studies using monoclonal antibodies against P450 2E1 showed that P450 2E1 accounted for about half of the activity in the metabolic activation of APAP in both mouse liver and kidney. Furthermore, there was a strong correlation between the renal P450 2E1 content (measured by Western blot analysis) and the rate of APAP oxidation by renal microsomes. To test the hypothesis that the susceptibility of renal tissue to APAP toxicity is determined by the distribution and level of P450 2E1, toxicity studies were conducted. A time-dependent depletion of hepatic and renal cortical glutathione was observed in both male and female mice following a dose of 1200 mg/kg APAP. At 4 hr after APAP dosing, the level of renal cortical glutathione depletion in male mice was significantly greater than that in the females. The level of blood creatinine elevation in male mice was higher than that in the females 8 hr after APAP dosing. Histopathology studies by light and electron microscopic assessments demonstrated that renal damage by APAP was restricted mostly to the epithelial cells of the proximal convoluted tubules where P450 2E1 was localized. The renal proximal tubular necrosis induced by APAP was more severe in males than that in the females. Results from this study suggest that P450 2E1 plays an important role in the metabolic activation of APAP and is a key factor in determining the sex-related difference of APAP-mediated toxicity in the mouse kidney.

BACKGROUND: Green tea has long been touted as a health promoting substance. The active chemical compounds in green tea are called polyphenols or catechins. Epigallocatechin gallate(EGCG) is the major catechin in green tea. We previously reported the in vitroability of EGCG to induce apoptotic cell death in chronic lymphocytic leukemia(CLL) B-cells in vitro (Blood 104:788). After publication of our findings, clinical activity in individuals using over the counter green tea extracts were reported (Leuk Res 30:707). Based on this information, we opened a phase I/II trial of green tea extracts for patients with asymptomatic, early stage CLL in fall of 2005.

BACKGROUND: Green tea has long been touted as a health promoting substance. The active chemical compounds in green tea are called polyphenols or catechins. Epigallocatechin gallate(EGCG) is the major catechin in green tea. We previously reported the in vitro ability of EGCG to induce apoptotic cell death in chronic lymphocytic leukemia(CLL) B-cells in vitro (Blood 104:788). After publication of our findings, clinical activity in individuals using over the counter green tea extracts were reported (Leuk Res 30:707). Based on this information, we opened a phase I/II trial of green tea extracts for patients with asymptomatic, early stage CLL in fall of 2005. METHODS: The purpose of the phase I portion of this trial was to determine the optimal dose of EGCG in the Polyphenon E preparation for chronic daily administration and define tolerability in CLL patients. Previously untreated patients with asymptomatic, Rai stage 0–II CLL not currently meeting National Cancer Institute(NCI) Working Group(WG) Criteria for treatment were eligible for participation. Polyphenon E with a standardized dose of EGCG was obtained from NCI. The phase I portion of the trial was designed with 8 dose levels(range 400–2000 mg orally BID) using the standard 3 patient per dose level design. Patients remained on study up to 6 months. Grade 2 adverse events attributed to study treatment that did not respond to supportive care were considered dose limiting toxicity. The trial was designed to administer Polyphenon E in the fasting state. After accrual to dose levels 1 and 2, the U.S. FDA mandated all U.S. trials of Polyphenon E administer drug in the fed state. Accordingly, drug was administered in the fed state for dose levels 3–8. Trough plasma EGCG levels were measured 1 month after initiation of therapy. Response was classified using the NCI WG Criteria. RESULTS: As of August 2007, 33 patients have been accrued to dose levels 1–8. The maximum tolerated dose(MTD) has not been reached. Side effects have generally been mild. The most common toxicities were nausea(grade 1: 42%; grade 2: 3%), elevation in SGOT (42%; all grade 1), and abdominal pain (36%; all grade 1). To date, no patient has had a sustained 50% reduction in both absolute lymphocyte count (ALC) and lymphadenopathy that would meet the NCI WG criteria for partial response. A majority of patients have had a reduction in ALC(Table). Among the 10 patients who had palpable adenopathy at study enrollment, 7 patients experienced at least a 50% reduction in the sum of the products of all nodal areas at some point during treatment. Trough plasma EGCG levels after 1 month of treatment ranged from 2.93974 ng/mL(median 40.5 ng/mL). Plasma levels did not clearly relate to the degree of reduction in ALC suggesting sensitivity to Polyphenon E may relate more to characteristics of the leukemic clone than plasma EGCG levels. CONCLUSION: Daily oral EGCG in the Polyphenon E preparation was well tolerated by CLL patients in this phase I trial. The MTD has not been reached. As classified by the NCI WG criteria, no partial or complete remissions have been observed to date, however declines in ALC and lymphadenopathy have been observed in the majority of patients. The phase II portion of this trial will open at Mayo Clinic Fall 2007. Best reduction in ALC n % of patients At least 10% decline 25 76% At least 20% decline 14 42% At least 30% decline 8 24% At least 40% decline 4 12% At least 50% decline 2 6%

The obstacle of inconsistent properties of CR-39 polycarbonate as etched track dosemeters has been overcome with the multi-stage thermal polymerisation of purified monomer. Excellent linear correlation of track density with neutron dosage was observed after chemical and/or electrochemical etching. Excellent tracks were also obtained for radon exposure. Copolymers of CR-39 with methyl acrylamido glycolate methyl ether, MAGME, have been explored as a means of improving track etching and better simulating human tissue.