Correction to: CD4 T cell count is positively associated with lumbar spine bone mass in HIV-infected men under the age of 50 years.

Two sentences in the Discussion section were incorrect.

CD4 T cell count is inversely associated with lumbar spine bone mass in HIV-infected men under the age of 50 years.

HIV-infected men under the age of 50 years had a lower bone mass compared to that of HIV-uninfected men. Lower CD4 T cell counts, independent of whether antiretroviral therapy (ART) was used, were associated with lower BMD. HIV-infected patients with low CD4 T cell counts may need follow-up and intervention regarding bone health, including younger patients. INTRODUCTION: HIV-infected patients have a low bone mineral density (BMD) owing to multifactorial interaction between common osteoporosis risk factors and HIV-related factors, including chronic inflammation and ART. Although HIV infection and ART might affect bone metabolism, little data is available for patients aged under 50 years. We aimed to investigate the association of HIV infection-induced low CD4 T cell counts and ART with BMD in men aged under 50 years. METHODS: We performed an age- and body mass index-matched case-control study. BMD values of HIV-infected and HIV-uninfected men (< 50 years) were compared, and HIV-infected men were stratified by CD4 T cell counts and ART use. RESULTS: After adjusting confounders, HIV-infected men with CD4 T cell counts ≥ 500 cells/µL (n = 28) and < 500 cells/µL (n = 139) had lower BMD at the femoral neck (FN, p < 0.001) and total hip (TH, p < 0.001) than HIV-uninfected men (n = 167). HIV-infected men with CD4 T cell counts < 500/µL had lower BMD at the lumbar spine (LS, p = 0.034) than those with counts of ≥ 500 cells/µL, but not at FN and TH. The CD4 T cell count (γ = 0.169, p = 0.031) was positively correlated with BMD at LS. There was no significant difference in the BMD (p = 0.499-> 0.999) between the ART-naïve (n = 75) and ART-user group (n = 92). CONCLUSIONS: Despite their relatively younger age, HIV-infected men had a lower BMD than HIV-uninfected men. Lower CD4 T cell counts, irrespective of ART, might result in lower bone mass.

Transfer printing of vertical-type microscale light-emitting diode array onto flexible substrate using biomimetic stamp.

We report the transfer printing of GaN-based microscale vertical-type light-emitting diodes (µ-VLEDs) using a functional layer and a biomimetic stamp. An oxide-based functional layer is inserted onto the structure of a µ-VLED and used to separate the chip from the µ-VLED wafer by absorbing the pulse of a UV pulse laser during pick-up of the transfer printing process. Polydimethylsiloxane (PDMS)-based biomimetic stamps have been fabricated to mimic the gecko lizard cilia for improved adhesion and repeatability. The biomimetic stamp has an adhesion force of 25.6 N/cm2, which is 12 times the adhesion of a flat stamp; an adhesion force of 10 N/cm2 or more was maintained after 100,000 repeated adhesion tests. A flexible 10 × 10 prototype array on a polyimide substrate was fabricated, and its bending test results indicated that the strain effect on the forward voltage and the output power was less than 1%. The stable bending test results of the prototype indicate that µ-VLEDs using biomimetic stamps allow the necessary stability for practical transfer printing.

Association of blood n-3 fatty acid with bone mass and bone marrow TRAP-5b in the elderly with and without hip fracture.

The plasma n-3 fatty acid level was 26.2% lower in patients with osteoporotic hip fracture than in those with osteoarthritis. In all patients, n-3 fatty acid was positively associated with bone mineral density and inversely associated with tartrate-resistant acid phosphatase-5b level in bone marrow aspirates, reflecting the bone microenvironment. INTRODUCTION: Despite the potential beneficial role of n-3 fatty acid (FA) on bone metabolism, the specific mechanisms underlying these effects in humans remain unclear. Here, we assessed whether the plasma n-3 level, as an objective indicator of its status, is associated with osteoporosis-related phenotypes and bone-related markers in human bone marrow (BM) samples. METHODS: This was a case-control and cross-sectional study conducted in a clinical unit. n-3 FA in the blood and bone biochemical markers in the BM aspirates were measured by gas chromatography/mass spectrometry and immunoassay, respectively. BM fluids were collected from 72 patients who underwent hip surgery because of either osteoporotic hip fracture (HF; n = 28) or osteoarthritis (n = 44). RESULTS: After adjusting for confounders, patients with HF had 26.2% lower plasma n-3 levels than those with osteoarthritis (P = 0.006), and each standard deviation increment in plasma n-3 was associated with a multivariate-adjusted odds ratio of 0.40 for osteoporotic HF (P = 0.010). In multivariate analyses including all patients, a higher plasma n-3 level was associated with higher bone mass at the lumbar spine (ß = 0.615, P = 0.002) and total femur (ß = 0.244, P = 0.045). Interestingly, the plasma n-3 level was inversely associated with the tartrate-resistant acid phosphatase-5b level (ß = - 0.633, P = 0.023), but not with the bone-specific alkaline phosphatase level, in BM aspirates. CONCLUSIONS: These findings provide clinical evidence that n-3 FA is a potential inhibitor of osteoclastogenesis that favors human bone health.

The association of cortisol and adrenal androgen with trabecular bone score in patients with adrenal incidentaloma with and without autonomous cortisol secretion.

Despite ethnic differences in cortisol sensitivity, only one study in Caucasians has assessed trabecular bone score (TBS) in patients with subclinical hypercortisolism (SH). We showed that both subtle cortisol excess and reduced adrenal androgen may contribute to impaired bone quality in Asian women with SH. INTRODUCTION: One study in Caucasians has assessed trabecular bone score (TBS), an index of bone microstructure, in adrenal incidentaloma (AI) patients with subclinical hypercortisolism (SH). There are ethnic differences in cortisol sensitivities between Caucasian and Asian populations. We investigated the associations of cortisol and the adrenal androgen dehydroepiandrosterone-sulfate (DHEA-S) with TBS in AI patients with SH, adrenal Cushing's syndrome (CS), and nonfunctional AI (NFAI). METHODS: We measured TBS, cortisol levels after the overnight 1 mg dexamethasone suppression test (1 mg DST), and cortisol/DHEA-S in 61 patients with SH (30 men; 31 women), 19 with adrenal CS (4 men; 15 women), and 355 with NFAI (213 men; 142 women). RESULTS: After adjusting for confounders, the serum cortisol level after 1 mg DST was inversely correlated with TBS in men (ß = -0.133, P = 0.045) and women (ß = - 0.140, P = 0.048). Higher cortisol/DHEA-S ratio was associated with lower TBS in women (ß = - 0.252, P < 0.001), but not men. This inverse association of cortisol/DHEA-S ratio in women remained statistically significant after adjusting for the serum cortisol level after 1 mg DST (ß = - 0.221, P = 0.008). Compared with women with NFAI, women with SH had 2.2% lower TBS (P = 0.040). Deteriorated bone microstructure (TBS < 1.230) was associated with the serum cortisol level after 1 mg DST (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.04-4.53) and cortisol/DHEA-S ratio (OR, 2.05; 95% CI, 1.03-4.08). CONCLUSIONS: Subtle cortisol excess in both genders and reduced DHEA-S, especially in women, may contribute to impaired bone quality in Asian patients with SH.

The impact of saddle embolism on the major adverse event rate of patients with non-high-risk pulmonary embolism.

OBJECTIVE: Wider application of CT angiography (CTA) improves the diagnosis of acute pulmonary embolism (PE). It also permits the visualisation of saddle embolism (SE), namely thrombi, which are located at the bifurcation of the main pulmonary artery. The aim of this study was to assess the prevalence of SE and whether SE predicts a complicated clinical course in patients with non-high-risk PE. METHODS: In total, 297 consecutive patients with non-high-risk PE confirmed using CTA in the emergency department were studied. The presence of SE and its ability to predict the occurrence of major adverse events (MAEs) within 1 month were determined. RESULTS: Of the 297 patients, 27 (9.1%) had an SE. The overall mortality at 1 month was 12.5%; no significant difference was observed between the SE and non-SE groups (18.5% vs 11.9%, p=0.32). However, patients with SE were more likely to receive thrombolytic therapy (29.6% vs 8.1%, p<0.01) and had significantly more MAEs (59.3% vs 25.6%, p<0.01). CONCLUSION: At the time of diagnosis, SE, as determined using CTA, is associated with the development of MAE within 1 month. It may be a simple method for risk stratification of patients with non-high-risk PE. ADVANCES IN KNOWLEDGE: The prognosis of patients with SE, especially those who are haemodynamically stable, is unclear. This study shows that patients with SE, determined with CTA, is associated with the development of MAE.

Intracardiac thrombus formation induced by carbon monoxide poisoning.

INTRODUCTION: Carbon monoxide (CO) is one of the leading causes of poisoning; it inhibits oxygen delivery, subsequently causing ischemic changes and ultimately death by multiorgan failure. Furthermore, thromboembolic episodes due to CO poisoning have been reported. However, intracardiac thrombus formation following exposure to CO has been very rarely described. Here, a case of right atrial large thrombus formation after CO poisoning is presented. CASE PRESENTATION: A previously healthy 24-year-old woman was referred for CO poisoning. She has attempted suicide, and her initial mental status was drowsy with focal memory loss. Her initial CO fraction was 16%, and initial laboratory data showed creatinine kinase-myocardial bound of 90.6 ng/mL (upper limit 5 ng/mL) and troponin I of 1.899 ng/mL (upper limit 1.5 ng/mL). A transthoracic echocardiography was performed 24 h after the accident, revealing a 30 15 mm nodular echogenic mass in the right atrium. Anticoagulation with low-molecular-weight heparin was started along with hyperbaric oxygen therapy. After 7 days of heparinization, the large thrombus in right atrium had resolved. CONCLUSION: This report describes an intracardiac thrombus formation induced by CO poisoning. Because intracardiac thrombus can result in pulmonary embolism and cerebral embolic infarction, its consideration following CO poisoning is important.

TrkC binds to the type II TGF-beta receptor to suppress TGF-beta signaling.

Growing evidence suggests that overexpression of TrkC, a member of the Trk family of neurotrophin receptors, could drive tumorigenesis, invasion and metastatic capability in cancer cells. However, relatively little is known about the mechanism of TrkC-mediated oncogenesis. The TrkC gene is a partner of the Tel-TrkC (ETV6-NTRK3) chimeric tyrosine kinase, a potent oncoprotein expressed in tumors derived from multiple cell lineages. Recently, we have shown that ETV6-NTRK3 suppresses transforming growth factor-beta (TGF-beta) signaling by directly binding to the type II TGF-beta receptor (TbetaRII). Here, we report that expression of TrkC also suppresses TGF-beta-induced Smad2/3 phosphorylation and transcriptional activation. Silencing TrkC expression by small interfering RNA in the highly metastatic 4T1 mammary tumor cell line expressing endogenous TrkC significantly enhanced TGF-beta-induced Smad2/3 phosphorylation and restored TGF-beta growth inhibitory activity. In contrast, expression of TrkC in 67NR cells, in which TrkC is not expressed, suppressed TGF-beta transcriptional activation. Moreover, we show that TrkC directly binds to the TbetaRII, thereby preventing it from interacting with the type I TGF-beta receptor (TbetaRI). These results indicate that TrkC is an inhibitor of TGF-beta tumor suppressor activity.

Role of phase 2 enzyme induction in chemoprotection by dithiolethiones.

One of the major mechanisms of protection against carcinogenesis, mutagenesis, and other forms of toxicity mediated by carcinogens is the induction of enzymes involved in their metabolism, particularly phase 2 enzymes such as glutathione S-transferases (GSTs), UDP-glucuronosyl transferases, and quinone reductases. Animal studies indicate that induction of phase 2 enzymes is a sufficient condition for obtaining chemoprevention and can be achieved by administering any of a diverse array of naturally-occurring and synthetic chemopreventive agents. Indeed, monitoring of enzyme induction has led to the recognition or isolation of novel, potent chemopreventive agents such as 1,2-dithiole-3-thiones, terpenoids and the isothiocyanate sulforaphane. For example, oltipraz, a substituted 1,2-dithiole-3-thione originally developed as an antischistosomal agent, possesses chemopreventive activity against different classes of carcinogens targeting multiple organs. Mechanistic studies in rodent models for chemoprevention of aflatoxin B(1) (AFB(1))-induced hepatocarcinogenesis by oltipraz indicates that increased expression of phase 2 genes is of central importance, although inhibition of phase 1 activation of AFB(1) can also contribute to protection. Exposure of rodents to 1,2-dithiole-3-thiones triggers nuclear accumulation of the transcription factor Nrf2 and its enhanced binding to the "antioxidant response element" (ARE), leading to transcriptional activation of a score of genes involved in carcinogen detoxication and attenuation of oxidative stress. Nrf2-deficient mice fail to induce many of these genes in response to dithiolethiones; moreover, basal expression of these genes is typically repressed. To test the hypothesis that enzyme induction is a useful strategy for chemoprevention in humans, three key elements are necessary: a candidate agent, an at-risk population and modulatable intermediate endpoints. Towards this end, a placebo-controlled, double blind clinical trial of oltipraz was conducted in residents of Qidong, PR China who are exposed to dietary aflatoxins and who are at high risk for the development of liver cancer. Oltipraz significantly enhanced excretion of a phase 2 product, aflatoxin-mercapturic acid, a derivative of the aflatoxin-glutathione conjugate, in the urine of study participants administered 125 mg oltipraz by mouth daily. Administration of 500 mg oltipraz once a week led to a significant reduction in the excretion of the primary oxidative metabolite of AFB(1), AFM(1), when measured shortly after drug administration. While this study highlighted the general feasibility of inducing phase 2 enzymes in humans, a longer term intervention is addressing whether protective alterations in aflatoxin metabolism can be sustained for extended periods of time in this high-risk population.

Antioxidative function and substrate specificity of NAD(P)H-dependent alkenal/one oxidoreductase. A new role for leukotriene B4 12-hydroxydehydrogenase/15-oxoprostaglandin 13-reductase.

There are several known routes for the metabolic detoxication of alpha,beta-unsaturated aldehydes and ketones, including conjugation to glutathione and reduction and oxidation of the aldehyde to an alcohol and a carboxylic acid, respectively. In this study, we describe a fourth class of detoxication that involves the reduction of the alpha,beta-carbon=carbon double bond to a single bond. This reaction is catalyzed by NAD(P)H-dependent alkenal/one oxidoreductase (AO), an enzyme heretofore known as leukotriene B4 12-hydroxydehydrogenase, 15-oxoprostaglandin 13-reductase, and dithiolethione-inducible gene-1. AO is shown to effectively reduce cytotoxic lipid peroxidation products such as 4-hydroxy-2-nonenal (HNE) (k(cat) = 4.0 x 10(3) min(-1); k(cat)/K(m) = 3.3 x 10(7) min(-1) M(-1)) and acrolein (k(cat) = 2.2 x 10(2) min(-1); k(cat)/K(m) = 1.5 x 10(6) min(-1) M(-1)) and common industrial compounds such as ethyl vinyl ketone (k(cat) = 9.6 x 10(3) min(-1); k(cat)/K(m) = 8.8 x 10(7) min(-1) M(-1)) and 15-oxoprostaglandin E1 (k(cat) = 2.4 x 10(3) min(-1); k(cat)/K(m) = 2.4 x 10(9) min(-1) M(-1)). Furthermore, transfection of human embryonic kidney cells with a rat liver AO expression vector protected these cells from challenge with HNE. The concentration of HNE at which 50% of the cells were killed after 24 h increased from approximately 15 microM in control cells to approximately 70 microM in AO-transfected cells. Overexpression of AO also completely abolished protein alkylation by HNE at all concentrations tested (up to 30 microM). Thus, we describe a novel antioxidative activity of a previously characterized bioactive lipid-metabolizing enzyme that could prove to be therapeutically or prophylactically useful due to its high catalytic rate and inducibility.

Role of transcription factor Nrf2 in the induction of hepatic phase 2 and antioxidative enzymes in vivo by the cancer chemoprotective agent, 3H-1, 2-dimethiole-3-thione.

BACKGROUND: The induction of phase 2 enzymes by dithiolethiones such as oltipraz is an effective means for achieving protection against environmental carcinogens in animals and humans. Transcriptional control of the expression of at least some of these protective enzymes is mediated through the antioxidant response element (ARE) found in the upstream regulatory region of many phase 2 genes. The transcription factor Nrf2, which binds to the ARE, appears to be essential for the induction of proto-typical phase 2 enzymes such as glutathione S-transferase (GST) Ya, Yp, and NAD(P)H: quinone reductase (NQO1) in vivo. MATERIALS AND METHODS: In the present study, 3H-1,2-dithiole-3-thione (D3T) was used as a potent model inducer whose effects on gene expression and chemopreventive efficacy have been extensively characterized in the rat. Over a dozen putative D3T-inducible genes were examined in wild-type and nrf2-disrupted mice by Northern blot hybridization and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis to elucidate whether loss of Nrf2 function also affects the induction of a broader representation of phase 2 and antioxidative enzymes. The effects of D3T on hepatic Nrf2 expression and localization were also examined in vivo by Northern blot hybridization, electromobility shift assay, and Western blot analysis. RESULTS: Specific activities of hepatic GST and NQO1 were increased by D3T in wild-type mice and were largely blunted in the nrf2-deficient mice. However, changes in levels of RNA transcripts following D3T treatment of nrf2-disrupted mice were multidirectional, dependent upon the particular gene examined. Although elevation of mRNAs for GST Ya, NQO1, microsomal epoxide hydrolase and gamma-glutamylcysteine synthetase regulatory chain were blocked in the mutant mice, elevation of GST Yp mRNA was largely unimpeded. Increases in levels of mRNA for the heavy and light chains of ferritin were only seen in the nrf2-disrupted mice. Transcript levels of UDP-glucuronyl-transferase 1A6, heme oxygenase-1, maganese superoxide dismutase, which were inducible in the wild-type mice, actually decreased in the mutant mice, whereas levels of mRNA for GST Yc, aflatoxin B1 aldehyde reductase and catalase decreased following D3T treatment in the mutant mice in the absence of any inductive effect by D3T in the wild-type mice. In wild-type mice, treatment with D3T lead to 3-fold increases in hepatic Nrf2 mRNA levels within several hours following dosing as assessed by Northern blot and RT-PCR analyses. Gel shift analyses with oligonucleotide probes for human NQO1 ARE, murine GST Ya ARE, and erythroid transcription factor (NF-E2) binding site showed increased intensity of binding with nuclear extracts prepared from livers of D3T-treated mice compared to vehicle-treated controls. Antibody to Nrf2 supershifted the DNA binding bands of these nuclear extracts. Moreover, immunoblot analysis indicated accumulation of Nrf2 in extracts prepared from hepatic nuclei of D3T-treated mice at the same time points. CONCLUSIONS: Nrf2 plays a central role in the regulation of constitutive and inducible expression of multiple phase 2 and antioxidative enzymes by chemoprotective dithiolethiones in vivo, although patterns of response vary among different genes. Knowledge of the factors controlling the specificity of actions of enzyme inducers will be exceedingly helpful in the design and isolation of more efficient and selective chemoprotective agents.

Sensitivity to carcinogenesis is increased and chemoprotective efficacy of enzyme inducers is lost in nrf2 transcription factor-deficient mice.

Induction of phase 2 enzymes, which neutralize reactive electrophiles and act as indirect antioxidants, appears to be an effective means for achieving protection against a variety of carcinogens in animals and humans. Transcriptional control of the expression of these enzymes is mediated, at least in part, through the antioxidant response element (ARE) found in the regulatory regions of their genes. The transcription factor Nrf2, which binds to the ARE, appears to be essential for the induction of prototypical phase 2 enzymes such as glutathione S-transferases (GSTs) and NAD(P)H:quinone oxidoreductase (NQO1). Constitutive hepatic and gastric activities of GST and NQO1 were reduced by 50-80% in nrf2-deficient mice compared with wild-type mice. Moreover, the 2- to 5-fold induction of these enzymes in wild-type mice by the chemoprotective agent oltipraz, which is currently in clinical trials, was almost completely abrogated in the nrf2-deficient mice. In parallel with the enzymatic changes, nrf2-deficient mice had a significantly higher burden of gastric neoplasia after treatment with benzo[a]pyrene than did wild-type mice. Oltipraz significantly reduced multiplicity of gastric neoplasia in wild-type mice by 55%, but had no effect on tumor burden in nrf2-deficient mice. Thus, Nrf2 plays a central role in the regulation of constitutive and inducible expression of phase 2 enzymes in vivo and dramatically influences susceptibility to carcinogenesis. Moreover, the total loss of anticarcinogenic efficacy of oltipraz in the nrf2-disrupted mice highlights the prime importance of elevated phase 2 gene expression in chemoprotection by this and similar enzyme inducers.

Molecular basis for hepatic detoxifying enzyme induction by 2-(allylthio)pyrazine in rats in comparison with oltipraz: effects on prooxidant production and DNA degradation.

The expression of hepatic microsomal epoxide hydrolase (mEH) and glutathione S-transferases (GSTs) by 2-(allylthio)pyrazine (2-AP), an experimental chemopreventive agent, was investigated in rats. Northern blot analysis revealed that 2-AP caused increases in mEH, rGSTA2/3/5, and rGSTM1/2 mRNA levels. mEH and rGSTA2 proteins were also induced. Molecular basis of the enzyme induction by 2-AP was studied in comparison with oltipraz (Olt). Rats exposed to buthionine sulfoximine, a GSH-depleting agent, before treatment with either 2-AP or Olt exhibited greater increases in the mRNA levels than the individual treatment. Conversely, increases of the mRNAs were prevented by cysteine treatment, indicating that metabolic intermediates or reactive oxygens produced from the agents could be reduced by cysteine. Gel shift analysis revealed that nuclear factor-kappaB, which is associated with the altered cellular redox state, was not activated by the agents. Effects of these agents on the breakage of phix-174 DNA were compared in vitro. 2-AP effectively reduced the conversion of supercoiled DNA to the open circular form induced by benzenetriol and prevented benzenetriol- and iron-catalyzed degradation of DNA, whereas Olt failed to prevent strand breakage of DNA. These results provided evidence that: 1) 2-AP was effective in elevating the hepatic mEH and GST gene expression in rats, which might be mediated with the production of reactive oxygen species; 2) nuclear factor-kappaB activation was not involved in the induction of the detoxifying enzymes by either 2-AP or Olt in spite of their production of reactive oxygens in vivo; and 3) the antioxidant effect of 2-AP in vitro differed from that of Olt.

Inhibition of cytochrome P450 2E1 expression by 2-(allylthio)pyrazine, a potential chemoprotective agent: hepatoprotective effects.

Cytochrome P450 2E1 (P450 2E1) is active in both the detoxification and activation of small organic molecules. The effects of 2-(allylthio)pyrazine (2-AP) on P450 2E1-catalytic activity and the expression of rat hepatic P450 2E1 were examined. 2-AP competitively inhibited 4-nitrophenol hydroxylase activity in vitro (Ki, 12 microM). 2-AP treatment of rats (200 mg/kg/day, p.o., 1-3 days old) resulted in 20-30% decreases in the rates of P450 2E1-specific metabolic activities. Immunoblot analysis also revealed that hepatic microsomes isolated from 2-AP-treated rats showed substantial decreases in P450 2E1 level. 2-AP-suppressed isoniazid (INH)-inducible hepatic P450 2E1 levels, as shown by both metabolic activities and immunoblot analyses. Thus, 2-AP was effective in suppressing both constitutive and inducible P450 2E1 expression. Northern blot analysis showed that 2-AP transiently suppressed the hepatic P450 2E1 mRNA level, suggesting that suppression in P450 2E1 expression by 2-AP may be mediated in part by transcriptional inactivation. Hepatoprotective effects of 2-AP against toxicants were monitored in mice. 2-AP pretreatment prior to the administration of lethal doses of acetaminophen (AAP) or INH substantially reduced toxicant-induced mortality. Whereas serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were markedly elevated after AAP administration (i.e. 9-20-fold), 2-AP pretreatment of animals before AAP administration resulted in >95% decreases in elevated serum aminotransferase activities. 2-AP was also effective against CCl4-induced hepatotoxicity. Whereas CCl4 treatment caused 35-70-fold increases in aminotransferase activities, treatment of mice with 2-AP (>10 mg/kg) resulted in the blocking of CCl4-induced liver toxicity. The hepatoprotective effect of 2-AP was in part due to 2-AP-induced elevation of hepatic GSH levels. Whereas AAP or CCl4 treatment resulted in 70-80% reduction in hepatic GSH levels, pretreatment of mice with 2-AP caused a 40-210% elevation in hepatic GSH levels, as compared with either AAP or CCl4 alone. 2-AP pretreatment also reduced AAP- or CCl4-induced increases in lipid peroxidation in a dose-dependent manner. The results of these metabolic activities and of immunoblot and RNA blot analyses demonstrate that 2-AP is efficacious in suppressing constitutive and inducible P450 2E1 expression and effective in protecting against toxicant-induced liver toxicity.

Effects of garlic oil on rat hepatic P4502E1 expression.

1. The effects of garlic oil (GO) on the expression of P4502E1, glutathione S-transferase (GST) and microsomal epoxide hydrolase (mEH) were assessed by metabolic activities, immunoblot and RNA blot analyses in the rat. 2. p-Nitrophenol (PNP) hydroxylase activity decreased in the hepatic microsomes isolated from rats treated with GO at 200 mg/kg b.w. by 10-30% as compared with control. Pyrazine-inducible P4502E1 expression was decreased by approximately 40% following concomitant treatment of animals with GO at the dose of 200 mg/kg from day 1 to 3 post-treatment, as evidenced by PNP hydroxylase activity. The rates of aniline hydroxylase and NDMA demethylase activities in GO-treated animals were consistent with those of PNP hydroxylase activity. Treatment of animals with 500 mg/kg GO resulted in suppression of P4502E1-mediated catalytic activities, as monitored by both PNP and aniline hydroxylase activities, whereas the effects at the dose of 1000 mg/kg were identical with those at 500 mg/kg b.w. 3. Immunoblot analyses of hepatic microsomes, using an anti-P4502E1 antibody, showed that GO minimally suppressed constitutive P4502E1 expression at 24, 48 and 72 h post-treatment at the daily doses from 200 to 1000 mg/kg b.w., as compared with vehicle-treated animals. Time-dependent pyrazine induction of P4502E1, however, was substantially blocked by concomitant treatment of animals with 200 mg/kg GO to the levels of control. Treatment at the dose of 1000 mg/kg failed to further suppress P4502E1 levels. GO treatment caused no changes in the levels of P4502E1 mRNA, as assessed by slot blot analyses. 4. Cytosol produced from the GO-treated rat showed approximately 40% increases in GST conjugating activity toward 1-chloro-2,4-dinitrobenzene, whereas mEH protein levels were 1.5-2.0-fold greater than control with similar increases in the mRNA levels noted. 5. These results demonstrate that GO suppresses inducible P4502E1 expression more significantly than constitutive expression, and that GO induces GST and mEH expression to a certain extent.

Inhibition of cytochrome P4502E1 expression by organosulfur compounds allylsulfide, allylmercaptan and allylmethylsulfide in rats.

Cytochrome P4502E1 (CYP2E1) is active in both detoxication and activation of small organic molecules. The effects of organosulfur compounds including allylsulfide (AS), allylmercaptan (AM) and allylmethylsulfide (AMS) on the expression of CYP2E1 were examined in rats. 4-Nitrophenol, aniline hydroxylase and N-nitrosodimethylamine demethylase activities, the rates of which represent the level of CYP2E1, decreased in hepatic microsomes isolated from rats treated with AS in a time-dependent manner by 45% to 90%, as compared to control. Pyrazine-induced hepatic microsomes exhibited approximately 5-fold increases in CYP2E1-catalysed metabolic activities, whereas the hepatic microsomes obtained after treatment of animals with both AS and pyrazine showed rates comparable to or less than those in control microsomes. AM or AMS suppressed constitutive and pyrazine-inducible levels of CYP2E1 similarly to AS. Immunoblot analyses of hepatic microsomes, using an anti-CYP2E1 antibody, showed that AS, AM and AMS significantly suppressed constitutive levels of CYP2E1 apoprotein after 24, 48 and 72 hr. Time-dependent induction of CYP2E1 by pyrazine was also completely blocked by treatment of animals with AS throughout the experimental period, as evidenced by immunoblot analysis. The levels of CYP2E1 apoprotein in the hepatic microsomes isolated from animals treated with both AM and pyrazine, or with both AMS and pyrazine were comparable to those in control hepatic microsomes at days 1-3 post-treatment. Treatment of rats with each of these organosulfur compounds caused no significant changes in the levels of CYP2E1 mRNA, as assessed by slot and northern blot analyses, suggesting that post-transcriptional regulation may be associated with the suppression of CYP2E1 apoprotein levels. The results of metabolic activities, immunoblot analyses and RNA blot analyses demonstrated that these organosulfur compounds are effective in suppressing constitutive and inducible expression of CYP2E1.

Enhanced expression of rat microsomal epoxide hydrolase gene by organosulfur compounds.

The effects of organosulfur compounds including allylsulfide (AS), allylmercaptan (AM) and allylmethylsulfide (AMS) on the expression of microsomal epoxide hydrolase (mEH) protein and its mRNA were examined in rats. The levels of mEH induction were examined with or without concomitant treatment of animals with pyrazine, a strong inducer of mEH, in order to establish whether a common molecular basis exists for mEH induction between these structurally different xenobiotics. Immunoblot analyses using anti-rat mEH antibody showed that treatment with AS caused an approximately 4-fold increase in hepatic mEH protein levels relative to controls whereas treatment with both AS and pyrazine resulted in only minimal additive increases in the elevation of mEH. Administration of AM to rats resulted in a comparable increase in mEH levels to that caused by AS, whereas an approximately 2-fold increase was noted after AMS treatment, as compared to control. mEH levels in the hepatic microsomes isolated from animals treated with both AMS and pyrazine were, however, approximately 50% less than those from pyrazine-treated rats. Thus, AS and AM appeared to be more effective than AMS in elevating mEH, as evidenced by immunoblot analyses. The levels of mEH mRNA were increased 10-16-fold following treatment with either AS or AM, while AMS caused a 3-7-fold increase relative to control, as assessed by slot blot analysis probed with a 1.3 kb mEH cDNA. Time-dependent increases in mRNA levels by each of these organosulfur compounds were consistent with those in mEH protein levels at 3 days. A marginal additive increase in mEH mRNA levels was noted following co-administration of either AS or AM with pyrazine, whereas treatment with both AMS and pyrazine decreased mEH mRNA levels by 55%. Significant mEH mRNA increases in poly(A)+ RNA fractions were confirmed by northern blot analysis. The results demonstrate that these organosulfur compounds are inducers of mEH and that the induction involves increases in its mRNA.