Associations of various blood pressure parameters with functional outcomes after endovascular thrombectomy in acute ischaemic stroke.

BACKGROUND AND PURPOSE: High blood pressure (BP) at presentation is associated with poor outcomes in acute ischaemic stroke, but serial BP measurements may better delineate the clinical implications of BP. The aim was to investigate the association between various BP parameters and functional outcomes in acute ischaemic stroke patients treated with endovascular thrombectomy (EVT). METHODS: This study reports a retrospective analysis of a prospective registry of a comprehensive stroke centre. Patients treated with EVT due to large vessel occlusion in the anterior circulation were enrolled. BP was measured hourly during the first 24 h after admission. Associations of various BP parameters, including BP variability, with functional outcomes at 3 months, including good outcomes (modified Rankin Scale score of 0-2), were analysed. RESULTS: Of the 378 enrolled patients (mean age 70 ± 11 years, male 54.2%), 313 (82.8%) achieved successful reperfusion after EVT, and 149 (39.4%) had good outcomes at 3 months. Higher mean systolic BP [each 10 mmHg increase, odds ratio 0.82 (0.69-0.97)] and higher systolic successive variation (SV) [each 10% increase, odds ratio 0.37 (0.18-0.76)] were associated with a reduced likelihood of achieving good outcomes. In addition, reperfusion status after EVT moderated the influence of higher systolic SV on good outcomes (Pint  = 0.05). CONCLUSION: The results showed that a higher mean systolic BP and systolic SV during the first 24 h of EVT reduced the likelihood of good outcomes at 3 months. The effects of these parameters on outcomes are more substantial amongst patients with successful reperfusion after EVT, suggesting that different BP control strategies should be employed according to reperfusion status.

Association between information provision and decisional conflict in cancer patients.

BACKGROUND: In this study, we aimed to identify demographic and clinical variables that correlate with perceived information provision among cancer patients and determine the association of information provision with decisional conflict (DC). PATIENTS AND METHODS: We enrolled a total of 625 patients with cancer from two Korean hospitals in 2012. We used the European Organization for Research and Treatment of Cancer (EORTC) quality-of-life questionnaire (QLQ-INFO26) to assess patients' perception of the information received from their doctors and the Decisional Conflict Scale (DCS) to assess DC. To identify predictive sociodemographic and clinical variables for adequate information provision, backward selective logistic regression analyses were conducted. In addition, adjusted multivariate logistic regression analyses were carried out to identify clinically meaningful differences of perceived level of information subscales associated with high DC. RESULTS: More than half of patients with cancer showed insufficient satisfaction with medical information about disease (56%), treatment (73%), other services (83%), and global score (80%). In multiple logistic regression analyses, lower income and education, female, unmarried status, type of cancer with good prognosis, and early stage of treatment process were associated with patients' perception of inadequate information provision. In addition, Information about the medical tests with high DCS values clarity [adjusted odds ratio (aOR), 0.54; 95% confidence interval (CI) 0.30-0.97] and support (aOR, 0.53; 95% CI 0.33-0.85) showed negative significance. For inadequate information perception about treatments and other services, all 5 DCS scales (uncertainty, informed, values clarity, support, and effective decision) were negatively related. Global score of inadequate information provision also showed negative association with high DCS effective decision (aOR, 0.43; 95% CI 0.26-0.71) and DCS uncertainty (aOR, 0.46; 95% CI 0.27-0.77). CONCLUSION: This study found that inadequate levels of perceived information correlated with several demographic and clinical characteristics. In addition, sufficient perceived information levels may be related to low levels of DC.

Spontaneous resolution of post-transplant localized cytomegalovirus lymphadenitis mimicking tumor recurrence.

Compromised T-cell immunity persists for up to 1 year after autologous stem cell transplantation (ASCT), and patients treated with ASCT are more likely to develop atypical lymphoid hyperplasia that mimics tumor recurrence. Here, we present a case of cervical lymphadenitis due to cytomegalovirus (CMV) reactivation in a patient who had undergone ASCT for Burkitt lymphoma, which mimicked tumor recurrence on computed tomography and positron emission tomography-computed tomography 6 months after ASCT. This lesion was confined to the regional lymph nodes and was not accompanied by signs of systemic involvement, such as fever, splenomegaly, an elevated C-reactive protein level, or viremia. The localized CMV lymphadenitis resolved spontaneously without treatment after 6 months (12 months after ASCT) and the elevated CMV immunoglobulin-M titer normalized 6 months after resolution. Our experience with this case suggests that cautious follow-up without anti-CMV treatment should be considered in cases of post-ASCT localized CMV lymphadenitis without systemic involvement in patients with complete engraftment.

Paradoxical embolism as a cause of silent brain infarctions in healthy subjects: the ICONS study (Identification of the Cause of Silent Cerebral Infarction in Healthy Subjects).

BACKGROUND: In healthy elderly people, silent brain infarctions (SBIs) have been recognized as common lesions. In this study, we evaluated the association between SBI located outside the perforating artery territory (PAT) and paradoxical embolism detected by agitated saline transcranial Doppler (TCD) monitoring in healthy subjects. METHODS: This was a prospective observational study undertaken by a university health promotion center for healthy subjects and by a university stroke center for acute stroke patients. We defined SBI as evidence on fluid-attenuation inversion recovery (FLAIR) magnetic resonance imaging (MRI) of one or more infarcts, without history of corresponding stroke or transient ischaemic attack. We also evaluated in all subjects the neuroimaging indicator of microangiopathy leukoaraiosis (LA). This study is registered with ClinicalTrials.gov, number NCT01429948. RESULTS: Amongst 1103 consecutive healthy adults who underwent MRI, 347 (31%) had one or more SBIs located outside the PAT, suggesting embolism. Amongst them, 253 subjects underwent agitated saline TCD monitoring and 128 (51%) had right-to-left shunts (RLS). The prevalence of RLS was similar to cryptogenic embolic stroke (62.0%, P = 0.056), but higher than in patients with other stroke subtypes (36.2%, P = 0.021). Amongst subjects with SBI, absence of LA was the only factor associated with RLS (OR 1.78; 95% CI 1.01-3.14; P = 0.046). CONCLUSION: Our results suggest that paradoxical embolism may play an important role in the development of SBI outside the PAT in apparently healthy adults.

Genetic factors in determining bone mass.

This investigation was undertaken to evaluate possible genetic determinants of bone mass with the premise that inheritance of bone mass could be of etiologic importance in osteoporosis. Bone mass and width measurements were made with the photon absorption technique on the right radius of 71 juvenile and 80 adult twin paris. The variance of intrapair differences of bone mass in monozygotic (MZ) juvenile twins was 0.0013 g(2)/cm(2) compared to 0.0052 g(2)/cm(2) in the dizygotic (DZ) twins. For the adult twins the variance of intrapair differences in bone mass was 0.0069 for MZ and 0.0137 for DZ twins. Similar results were obtained for bone width. The significantly larger variation in intrapair differences in DZ twins indicates that these traits have significant genetic determinants. These intrapair differences were found to increase with age, suggesting that genetic-environmental interaction also contributes to the observed variation in bone mass. These data provide evidence that bone mass does have significant genetic factors, which alone or in conjunction with environmental factors may predispose persons to the development of osteoporosis.

Ginsenoside Rd enhances glutathione levels in H4IIE cells via NF-kappaB-dependent gamma-glutamylcysteine ligase induction.

Panax ginseng is widely used as herbal medicine in East Asia and the pharmacological effects of P. ginseng against certain chronic diseases might be explained by its antioxidative effects. Here, we show that ginsenoside Rd significantly increases both cellular glutathione (GSH) contents and the protein level of gamma-glutamylcysteine ligase (gamma-GCL) heavy chain in H4IIE cells (a rat hepatocyte cell line). Subcellular fractionation and Western blot analysis revealed that ginsenoside Rd increased the nuclear level of p65, but not of Nrf2. Moreover, ginsenoside Rd increased luciferase reporter gene activity in cells transfected with nuclear factor-kappaB (NF-kappaB) binding site-containing -1088 bp gamma-GCL promoter. However, ginsenoside Rd-inducible reporter activity was abolished when cells were transfected with NF-kappaB deletion mutant. These effectsof ginsenoside Rd are suggested to underlie the putative anti-oxidative effect of Panax ginseng.

Mandibular symphyseal distraction osteogenesis with stepwise osteotomy in adult skeletal class III patient.

This technical note reports the use of symphyseal distraction with stepwise osteotomy in a case of lower anterior crowding and rotation in the incisor area. This technique allows for easy dental decompensation and reduced presurgical orthodontic time in skeletal class III cases.

Screening of new chemopreventive compounds from Digitalis purpurea.

Chemopreventive agents induce a battery of genes whose protein products can protect cells from chemical-induced carcinogenesis. In this study, we isolated four different glycosides (1 acteoside; 2 purpureaside A; 3 calceolarioside B; and 4, plantainoside D) from the leaves of Digitalis purpurea and studied their abilities to induce glutathione S-transferase (GST) and their protective efficiencies against aflatoxin B1-induced cytotoxicity in H4IIE cells. Of these four glycosides, acteoside significantly inhibited the cytotoxicity induced by aflatoxin B1 (AFB1) and also selectively increased GSTalpha protein levels. Reporter gene analysis using an antioxidant response element (ARE) containing construct and subcellular fractionation assays, revealed that GSTalpha induction by acteoside might be associated with Nrf2/ARE activation. The results suggest that acteoside possesses a potent hepatoprotective effect against AFB1 and that it can be applied as a potential chemopreventive agent.

ctr1, a gene involved in a signal transduction pathway of the gliding motility in the cyanobacterium Synechocystis sp. PCC 6803.

We generated random Tn5 mutations in Synechocystis sp. PCC 6803 in search for genes involved in the signal transduction cascade for the cyanobacterial gliding motility. One of the non-gliding Tn5 mutants, S1-105, had an insertional inactivation in the slr1044 gene encoding a putative methyl-accepting chemotaxis protein. Interposon mutation on the slr1044 (named ctr1) in the bacterium also eliminated gliding motility. In the interposon mutant, the expression of pilA1 was 5-fold decreased compared with that of wild-type and thick pili, that are believed to be the motor for gliding, could not be observed by an electron microscope. Therefore, we suggest that the Ctr1 protein functions as a transducer that regulates the expression of pilA1, and thus is required for the biogenesis of thick pili.

Late postictal residual perfusion abnormality in epileptogenic zone found on 6-hour postictal SPECT.

BACKGROUND: Temporal evolution of regional hyperperfusion in the late postictal stage in epilepsy has not been clearly defined. OBJECTIVE: To establish the late temporal evolution of the perfusion in epileptogenic zones using 6-hour postictal SPECT. METHODS: Ictal 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) SPECT was performed in 10 patients with intractable epilepsy (4 temporal lobe epilepsy, 6 neocortical epilepsy) followed by delayed acquisition and another 6-hour postictal SPECT after reinjection of 99mTc-HMPAO. The delayed acquired SPECT was subtracted from the reinjection SPECT to yield the 6-hour postictal SPECT. Interictal SPECT was acquired on another day. Late postictal perfusion was examined visually, and asymmetric indexes were compared with each other on ictal, 6-hour postictal, and interictal SPECT. RESULTS: Ictal SPECT images of delayed acquisition were visually and quantitatively similar to those of early acquisition. In 7 of 10 patients, 6-hour postictal SPECT showed hyperperfusion. In one patient, the 6-hour postictal SPECT image showed less perfusion than the interictal SPECT image in the epileptogenic zone. CONCLUSIONS: Late postictal hyperperfusion was found in more than half of the patients. Postictal perfusion abnormalities did not come back to the interictal phase 6 hours after ictus and these were identified on ictal/postictal 99mTc- HMPAO SPECT.

Potentiation of cadmium-induced cytotoxicity by sulfur amino acid deprivation through activation of extracellular signal-regulated kinase1/2 (ERK1/2) in conjunction with p38 kinase or c-jun N-terminal kinase (JNK). Complete inhibition of the potentiated toxicity by U0126 an ERK1/2 and p38 kinase inhibitor.

The mechanisms of cadmium-induced toxicity may include oxidative stress, altered redox homeostasis, and injuries to organelles. The current study was designed to study the effect of decreased cellular glutathione (GSH) content by sulfur amino acid deprivation on cadmium toxicity and to identify the signaling pathways responsible for the cytotoxicity. GSH content was increased by cadmium in H4IIE cells prior to cell death, which was prevented by excess GSH or cysteine. Cell viability, however, was not improved by GSH or cysteine complexation of cadmium. Cadmium-induced cytotoxicity was 40-fold potentiated in cells with decreased GSH by sulfur amino acid deprivation. Cadmium in combination with decreased GSH markedly increased apoptotic cell death. Mitogen-activated protein kinases including extracellular signal-regulated kinase 1/2, p38 kinase and c-Jun N-terminal kinase (JNK) were all activated 1-12 hr after sulfur amino acid deprivation. U0126 (1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene), which inhibited activation of extracellular signal-regulated kinase1/2 and p38 kinase in cells under sulfur amino acid deprivation, completely prevented potentiation in Cd-induced cytotoxicity and apoptosis. Potentiation of cadmium toxicity by sulfur amino acid deprivation was prevented in part by either PD98059 or SB203580, or in cells stably expressing dominant negative mutant of JNK1, and to greater extents by PD98059 in combination with either SB203580 or JNK1(-) transfection. These results demonstrated that decreased cellular GSH content potentiated cytotoxicity induced by cadmium at the level of human exposure, and that the potentiation of cytotoxicity resulted from activation of extracellular signal-regulated kinase1/2 in conjunction with p38 kinase or JNK.

Domain and genomic sequence analysis of bdellin-KL, a leech-derived trypsin-plasmin inhibitor.

Bdellin-KL is a trypsin-plasmin inhibitor from Hirudo nipponia, whose N-terminal sequence was identified as a non-classical Kazal-type. A cDNA clone encoding the inhibitor was isolated by reverse transcription-PCR and 5' rapid amplification of cDNA ends. The cDNA showed an open reading frame of 155 amino acids comprising one signal peptide and two separated domains. The C-terminal domain consists of distinct internal repeats, including HHEE and HHDD. The bdellin-KL sequence, from the constructed genomic library of Korean leech, was determined for the 2109 bases comprising the open reading frame and flanking regions (3' and 5'). The promoter region contains potential regulatory sequence motifs, including TATA, CAAT, and GC boxes. To characterize the properties of each domain, an N-terminal fragment was prepared by limited proteolysis of the intact protein. The inhibitory activity of the region was as potent as that of the intact protein. This suggests that the compact domain plays an important part in the inhibitory action of bdellin-KL. The C-terminal domain was revealed to have binding affinity to ions such as Ca(2+), Zn(2+), Fe(3+), and Fe(2+) without an influence on the inhibitory activity. This study demonstrates that bdellin-KL may be a novel bifunctional protein with two distinct domains.

Effects of bovine prostate powder on zinc, glucose, and insulin metabolism in old patients with non-insulin-dependent diabetes mellitus.

Since rabbit prostate extract strongly stimulated intestinal zinc absorption and improved the diabetic condition of streptozotocin-induced diabetic rats, we examined the effects of 200 mg bovine prostate powder supplemented with 20 mg zinc (Pro-Z) on the clinical manifestations of older male patients with type II diabetes. Twenty-two male patients who received Pro-Z capsules two to four times per day for 3 months showed reduced mean fasting blood glucose levels from 202 to 169 mg/dL, hemoglobin A1C-(HbA1C) concentrations from 12.2% to 9.5%, and mean values for the 3-hour area response above the fasting glucose concentration (TAFGC) from 141 to 102 mg glucose/dL/h. In eighteen patients who received placebo, mean values for fasting blood glucose decreased from 167 to 165 mg/dL and HbA1C from 10.4% to 10.2%, and for TAFGC increased from 121 to 126 mg glucose/dL/h. No detrimental changes occurred in the liver and kidney function of patients receiving either Pro-Z or placebo. However, blood cholesterol and low-density lipoprotein in patients receiving Pro-Z decreased slightly, whereas values in the placebo group tended to increase. The mean fasting plasma insulin decreased 15.5 to 13.8 microU/mL in subjects given Pro-Z, while the zinc concentration increased from 1.21 to 1.39 microg/mL. In contrast, the mean value for plasma insulin in the placebo group changed from 14.4 to 15.4 microU/mL (worsened), and for zinc, from 1.24 to 1.30 microg/ml. Interestingly, fasting urinary glucose concentrations in subjects given Pro-Z decreased from 1,249 to 378 mg/dL, whereas in those given placebo the values changed from 877 to 778 mg/dL. Since plasma zinc concentrations in both the placebo and the Pro-Z group were normal, these results suggest that biochemical constituents in the prostate including zinc may be involved in controlling glucose metabolism in patients with non-insulin-dependent diabetes mellitus.

Colchicine activates actin polymerization by microtubule depolymerization.

Swiss 3T3 fibroblasts were treated with the microtubule-disrupting agent colchicine to study any interaction between microtubule dynamics and actin polymerization. Colchicine increased the amount of filamentous actin (F-actin), in a dose- and time-dependent manner with a significant increase at 1 h by about 130% over control level. Confocal microscopic observation showed that colchicine increased F-actin contents by stress fiber formation without inducing membrane ruffling. Colchicine did not activate phospholipase C and phospholipase D, whereas lysophosphatidic acid did, indicating that colchicine may have a different mechanism of actin polymerization regulation from LPA. A variety of microtubule-disrupting agents stimulated actin polymerization in Swiss 3T3 and Rat-2 fibroblasts as did colchicine, but the microtubule-stabilizing agent taxol inhibited actin polymerization induced by the above microtubule-disrupting agents. In addition, colchicine-induced actin polymerization was blocked by two protein phosphatase inhibitors, okadaic acid and calyculin A. These results suggest that microtubule depolymerization activates stress fiber formation by serine/threonine dephosphorylation in fibroblasts.

DA-125, a novel anthracycline derivative showing high-affinity DNA binding and topoisomerase II inhibitory activities, exerts cytotoxicity via c-Jun N-terminal kinase pathway.

PURPOSE: DA-125 [(8S,10S)-8-(3-Aminopropanoyloxyacetyl)-10-[(2,6-dideoxy-2-fluoro-alpha-L-talopyranosyl) oxy]-7,8,9,10-tetrahydro-6,8,11-trihydroxy-1-methoxy-5,12-naphthacene-dione hydrochloride] is a novel anthracycline derivative with anticancer activity. In the present study, we compared the cytotoxicity of DA-125 with that of doxorubicin in H4IIE rat hepatoma cells and investigated the mechanistic basis. Because activation of MAP kinases, in particular c-Jun N-terminal kinase (JNK), is implicated in apoptotic cell death, the signaling pathways responsible for DA-125-induced apoptosis were studied. METHODS: Cytotoxicity and apoptosis were measured in H4IIE cells and cells were stably transfected with a dominant-negative mutant of JNK1 (JNK1-) by MTT and TUNEL assays. Inhibition of topoisomerase II activity was determined in vitro. Drug accumulation and DNA binding affinity were determined by fluorescence spectroscopy. RESULTS: The cytotoxicity of DA-125 was greater than that of doxorubicin (IC50 11.5 vs 70 microM). DA-125 induced apoptosis with 30-fold greater potency than doxorubicin. Inhibition of topoisomerase II by DA-125 was fourfold greater. The presence of excess beta-alanine, a DA-125 moiety, failed to alter cytotoxicity and accumulation of DA-125, indicating that the improved cytotoxicity of DA-125 did not result from the beta-alanine moiety. Greater cellular accumulation of DA-125 correlated with its high-affinity DNA binding. Although neither PD98059 nor SB203580 altered the degree of cytotoxicity induced by DA-125, JNK1 cells exhibited about a twofold greater viability than control cells. DA-125-induced apoptosis was also decreased in JNK1- -transfected cells. CONCLUSIONS: DA-125 potently inhibited topoisomerase II activity and induced apoptosis by a high rate of prooxidant production. DA-125 exhibited high-affinity DNA binding with improved cellular drug accumulation. Apoptosis induced by DA-125 involved the pathway of JNK1, but not ERK1/2 or p38 kinase.

In vitro inhibition of gap junctional intercellular communication by chemical carcinogens.

This study was conducted to assess the effects of chemical carcinogens on the gap junction-mediated intercellular communication in cultured mammalian cells. The method of scrape-loading dye transfer of lucifer yellow was adapted as a measure of gap junctional communication. Clone 9 cells derived from rat liver were treated with a model chemical carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and the gap junctional communication was assessed by measuring the transfer of scrape-loaded lucifer yellow dye. When cells were treated with the carcinogen at 0.3 mg/ml, the fluorescent dye transfer was inhibited by 90% in 60 min. Other chemical agents, which include direct or indirect carcinogens and antitumor drugs, were also examined for their effects on the gap junctional communication. Direct carcinogens, such as MNNG, hydroxylamine and ethidium bromide, exhibited strong inhibition of intercellular communication, while indirect carcinogens, such as aflatoxin B1 and ethionine, exerted minor effects. Effects of test chemicals on the cell communication through gap junctions were readily quantitated by counting the number of cells stained with the fluorescent dye.

Procyanidins in crataegus extract evoke endothelium-dependent vasorelaxation in rat aorta.

The extract of Crataegus, a mixture of flavonoids and procyanidins extracted from hawthorn, Crataegus oxyacantha, L. and C. monogyna Jacq., relaxed vascular tone or increased production of cyclic GMP in the rat aorta, but flavonoid components of Crataegus extract, hyperoside, rutin and vitexin, did not affect the vascular tone. The aim of the present study was to characterize the endothelium-dependent relaxation elicited by procyanidins fractionated from Crataegus extract in isolated rat aorta. Procyanidins caused endothelium-dependent relaxation which was associated with the production of cyclic GMP. Both responses to these procyanidins were inhibited by methylene blue or N(G)-nitro-L-arginine, but not by indomethacin. Relaxation in response to procyanidins was not affected by atropine, diphenhydramine, [D-Pro2,D-Trp7,9]substance P, propranolol, nifedipine, verapamil and glibenclamide, but were markedly reduced by tetraethylammonium. These findings showed that procyanidins in Crataegus extract may be responsible for the endothelium-dependent nitric oxide-mediated relaxation in isolated rat aorta, possibly via activation of tetraethylammonium-sensitive K+ channels.

Role of glucose utilization in the restoration of hypophysectomy-induced hepatic cytochrome P450 2E1 by growth hormone in rats.

Growth hormone and insulin are the primary determinants for cytochrome P450 2E1 (CYP2E1) expression. The role of glucose on the induction of CYP2E1 by hypophysectomy and on the restorative effect by growth hormone was investigated in the rat liver. Western and Northern blot analyses revealed that hypophysectomy induced CYP2E1 by 5-fold at 1-4 weeks, relative to control, with a concomitant increase in CYP2E1 mRNA. Hypophysectomized rats (HXR) showed a 20% reduction in the plasma glucose level. Hypophysectomy-induced increase in the CYP2E1 mRNA was completely abolished by glucose feeding in drinking water (10%) for 7 days. Treatment of HXR with hGH (2 I.U./kg, twice a day, for 7 days) inhibited the increases in CYP2E1 protein and mRNA levels with restoration of the plasma glucose level. In contrast to the effect of human growth hormone (hGH) on CYP2E1 in HXR with free access to foods, CYP2E1 expression failed to be restored by hGH in starving HXR. However, glucose feeding of starving HXR abolished the induction of CYP2E1. Effects of hypophysectomy and hGH treatment were studied in streptozotocin-induced diabetic rats. Insulin, but not hGH, prevented an increase in CYP2E1 mRNA in diabetic rats. The hepatic CYP2E1 induction in hypophysectomized diabetic rats was inhibited by hGH treatment, indicating that the hGH effect on CYP2E1 expression did not involve insulin production. These results provide evidence that the induction of hepatic CYP2E1 by hypophysectomy may result from reduced glucose utilization, and that the effect of hGH on CYP2E1 expression may be mediated with enhanced glucose utilization, but not with insulin production.

Activation of phosphatidylinositol 3-kinase by oxidative stress leads to the induction of microsomal epoxide hydrolase in H4IIE cells.

We have shown that PI3-kinase played an essential role in the ARE-mediated rGSTA2 induction by oxidative stress following SAAD (Mol. Pharmacol. 58 (2000) 1017). Microsomal epoxide hydrolase (mEH), which detoxifies a variety of epoxide intermediates produced from various xenobiotics, is inducible by oxidative stress. In the present study, we studied whether sulfur amino acid deprivation (SAAD) activated phosphatidylinositol 3-kinase (PI3-kinase)/Akt and induced mEH in H4IIE cells. The role of PI3-kinase activation on the mEH induction by SAAD was also investigated. PI3-kinase was activated from 10 min through 12 h after SAAD, the activity of which returned to control level at 24 h. The activation of PI3-kinase led to increases in the activity of Akt at the same time points. Northern and Western blot analyses revealed that the mEH mRNA level was four-fold increased at 48 h, which accompanied the induction of mEH protein. Wortmannin or LY294002, PI3-kinase inhibitors, completely inhibited the increases in mEH mRNA and protein by SAAD. These results demonstrated that SAAD activated the PI3-kinase/Akt pathway at early stages and induced mEH, presumably as an adaptive response, and that the PI3-kinase/Akt pathway played a crucial role in the induction of mEH.

Potentiation of arsenic-induced cytotoxicity by sulfur amino acid deprivation (SAAD) through activation of ERK1/2, p38 kinase and JNK1: the distinct role of JNK1 in SAAD-potentiated mercury toxicity.

Sulfur amino acid deficiency occurs in certain pathophysiological situations (e.g. protein-calorie malnutrition). Previous studies revealed that sulfur amino acid deprivation (SAAD) activated MAP kinases and potentiated cadmium-induced cytotoxicity by activation of ERK1/2 in conjunction with p38 kinase or JNK. The present study was designed to determine susceptibility of cells to a variety of heavy metals in combination with SAAD. Viability was assessed in H4IIE cells treated with sodium arsenite, mercuric chloride, sodium selenite, lead acetate, chromium trioxide or manganese chloride. SAAD potentiated the cytotoxicity of H4IIE cells by arsenic or mercury (i.e. EC50, 19 and 5 microM in SAAD vs. 401 and 42 microM in control medium, respectively). TUNEL assays revealed that the potentiated arsenic or mercury toxicity involved apoptotic cell death. Lead or selenite moderately elicited cell death, which was not enhanced by SAAD. Chromium or manganese caused no significant cytotoxicity. Treatment of cells with U0126 [1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene] an ERK1/2 inhibitor or SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole] a p38 kinase inhibitor effectively prevented SAAD-potentiated arsenic toxicity. The potentiated arsenic toxicity was also inhibited in cells stably expressing a dominant negative mutant of c-Jun N-terminal kinase 1 [JNK1(-)]. The inhibitors of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 kinase failed to prevent mercury-induced toxicity enhanced by SAAD. JNK1(-) cells were minimally susceptible to mercury in SAAD medium. These results demonstrated that SAAD potentiated cytotoxicity induced by arsenic or mercury and that activation of ERK1/2, p38 kinase and JNK1 was responsible for the potentiated arsenic toxicity, whereas the mercury toxicity enhanced by SAAD was mediated with the activity of JNK1.