Portal vein stenting to treat portal vein tumor thrombus in hepatocellular carcinoma

Tumor thrombus in the portal vein is refractory to therapy and a serious negative prognostic factor in hepatocellular carcinoma. We describe herein the case of a patient in whom an expandable metallic stent was successfully employed to treat portal vein tumor thrombus by restoring blood flow. An expandable metallic stent was implanted in a patient with severe main portal vein stenosis caused by tumor thrombus protruding from the left portal vein branch. Immediately after stent placement, the stenotic lesion was effectively dilated, the portal blood flow restored, and portal hypertension relieved. Angiography, computed tomography, and doppler ultrasonography done 2 months after the stent placement revealed continued patency of the portal vein. Thus, intraportal placement of an expandable metallic stent appears to be an effective treatment for major portal vein tumor

Cardioprotective effects of nicorandil in rabbits anaesthetized with halothane: potentiation of ischaemic preconditioning via KATP channels

1. The roles of ATP-sensitive K+ channels (KATP channels) in ischaemic or pharmacological preconditioning in the rabbit heart remain unclear. Infarct limitation by ischaemic preconditioning was abolished by the KATP channel blocker glibenclamide under ketamine/xylazine anaesthesia, but not under anaesthesia induced by pentobarbital. Infarct limitation by the KATP channel opener pinacidil was detected under ketamine/xylazine anaesthesia, but not under pentobarbital anaesthesia. Thus, these effects appear to be anaesthetic dependent. 2. In the present study, we examined whether nicorandil (a KATP channel opener nitrate) exhibits cardioprotective actions under halothane anaesthesia, another commonly used volatile anaesthetic. Control animals were subjected to 40 min coronary occlusion and 120 min reperfusion. Before 40 min ischaemia, the nicorandil group received nicorandil (100 microg/kg per min, i.v., for 10 min), the 5' preconditioning (PC) group received 5 min ischaemia/20 min reperfusion, the 2.5'PC group received 2.5 min preconditioning ischaemia/20 min reperfusion, the nicorandil +2.5'PC group received both nicorandil and 2.5 min ischaemia/20 min reperfusion, the nicorandil +2.5'PC + 5-hydroxydecanoate (5HD) group received both nicorandil and 2.5 min ischaemia/20 min reperfusion in the presence of 5-hydroxydecanoate (5HD; a KATP blocker) and the 5HD group received 5 mg/kg, i.v., 5HD alone. Myocardial infarct size in control (n = 7), nicorandil (n = 5), 5'PC (n = 8), 2.5'PC (n = 5), nicorandil + 2.5'PC (n = 5), nicorandil + 2.5'PC + 5HD (n = 5) and 5HD (n = 4) groups averaged 44.4 +/- 3.6, 41.7 +/- 5.7, 17.8 +/- 3.2,* 34.1 +/- 4.8, 21.3 +/- 4.2,* 39.1 +/- 5.6 and 38.9 +/- 5.0% of the area at risk, respectively (*P <0.05 vs control). 3. Thus, nicorandil alone did not have an infarct size-limiting effect in halothane-anaesthetized rabbits. However, the results suggest that even when nicorandil alone does not demonstrate a direct cardioprotective effect, it may enhance ischaemic preconditioning via KATP channels. Key words: ATP-sensitive K+ (KATP) channel, ischaemic preconditioning, myocardial infarction, nicorandil, rabbit.

Differences in time course of myocardial mRNA expression in non-infarcted myocardium after myocardial infarction

In non-infarcted myocardium after myocardial infarction, the change of cardiac phenotypic modulation of contractile protein, extracellular matrix and intracellular Ca2+ transport protein, such as sarcoplasmic reticulum Ca2+(SR-Ca2+)-ATPase, Na+-Ca2+ exchanger, have a important role during cardiac remodeling. However, the time course in this gene expression in the adjacent and remote left ventricular, or right ventricular myocardium after myocardial infarction has not been well examined. The purpose of this study was to examine the left ventricular function and regional cardiac gene expression after myocardial infarction. Myocardial infarction was produced in Wistar rats by the ligation of the left anterior descending coronary artery. After 3 weeks, 2 months and 4 months from myocardial infarction, we performed Doppler echocardiography and measured the systolic and diastolic function. Then, we analyzed the contractile protein, extracellular matrix and intracellular Ca2+ transport protein mRNAs of cardiac tissues in the adjacent and the remote noninfarcted myocardium, and right ventricular myocardium by Northern blot hybridization. Fractional shortening of infarcted heart progressively decreased. Peak early diastolic filling wave (E wave) velocity increased, and the deceleration rate of the E wave velocity was more rapid in myocardial infarction areas. Atrial filling wave (A wave) velocity decreased, resulting in a marked increase in the ratio of E wave to A wave velocity. Expression of myocardial alpha-skeletal actin, beta-MHC and ANP mRNA, or collagen I and III mRNA were higher at 3 weeks after myocardial infarction. SR Ca2+-ATPase mRNA in the adjacent non-infarcted myocardium was decreased at 2 months, and that in remote myocardium was decreased at 4 months after infarction. Na+-Ca2+ exchanger mRNA levels were increased at 3 weeks, but was decreased at 2 months in the adjacent non-infarcted myocardium and at 4 months in the remote myocardium. These findings suggest that the compensation for myocardial infarction by myocardial gene expression in non-infarcted myocardium may occur at an early phase after myocardial infarction, and myocardial dysfunction may begin from adjacent to remote non-infarcted myocardium during progressive cardiac remodeling.

Effects of intravenous nicorandil on coronary circulation in humans: plasma concentration and action mechanism

We investigated the cardiovascular profile of nicorandil, an antianginal agent, in humans. Pharmacologically, nicorandil acts as both an adenosine triphosphate (ATP)-sensitive K+ (K(ATP)) channel opener and a nitrate. We examined which of these mechanistic components has a predominant vasodilatory effect at clinical doses. Fourteen patients underwent cardiac catheterization. The effects of the continuous intravenous infusion of nicorandil (12 mg/45 min) were examined in angiographically normal coronary arteries. Coronary vascular resistance was calculated from coronary artery diameter and coronary blood flow velocity measured using an intravascular Doppler catheter. We compared the hemodynamic responses to nicorandil with those to the intracoronary injection of nitroglycerin (250 microg) and papaverine (12 mg). The epicardial coronary arteries responded to nicorandil at the lowest plasma concentration examined (dilation of +14.0 +/- 3.3% at approximately 170 ng/ml), whereas dilation of the coronary resistance arteries (i.e., a decrease in coronary vascular resistance) took place only at higher concentrations (>200 ng/ml). Nitroglycerin caused no further changes in coronary artery diameter or coronary vascular resistance. Papaverine caused no further increase in coronary artery diameter, but markedly decreased coronary vascular resistance (1.6 +/- 0.3 to 0.4 +/- 0.1 mm Hg/ml/min; p < 0.05). Nicorandil significantly decreased pulmonary capillary wedge pressure (i.e., reduced cardiac preload) at a plasma level of >200 ng/ml, but did not change either systemic or pulmonary vascular resistance. Thus nicorandil preferentially dilated epicardial coronary arteries rather than coronary resistance arteries, and had a stronger effect on preload than on afterload. These changes in human coronary hemodynamics suggest that the nitrate actions of nicorandil as a coronary vasodilator predominate over those as a K(ATP) opener.

Phytoreovirus T = 1 core plays critical roles in organizing the outer capsid of T = 13 quasi-equivalence

The structures of the double-shelled rice dwarf virus and of its single-shell core have been determined by cryoelectron microscopy and image reconstruction. The core carries a prominent density located at each of the icosahedral faces of its T = 1 lattice. These protrusions are formed by outer shell trimers, tightly inserted at the threefold positions of the core. Such configuration of the core may guide the assembly of the outer shell, aided by lateral interactions between its subunits, into a T = 13 lattice. The organization of the phytoreovirus capsid elucidates for the first time a general model for assembling two unique T numbers of quasi-equivalence.

Long-acting calcium channel antagonist pranidipine prevents ventricular remodeling after myocardial infarction in rats

The purpose of this study was to examine the effects of the long-acting calcium channel antagonist pranidipine on ventricular remodeling, systolic and diastolic cardiac function, circulating humoral factors, and cardiac mRNA expression in myocardial infarcted rats. Myocardial infarction (MI) was produced by ligation of the coronary artery in Wistar rats. Three mg/kg per day of pranidipine was randomly administered to the infarcted rats. Hemodynamic measurements, Doppler echocardiographic examinations, analyses of the plasma levels of humoral factors, and myocardial mRNA expression were performed at 4 weeks after myocardial infarction. Left ventricular end-diastolic pressure (LVEDP) and central venous pressure (CVP) increased to 24.2 +/- 1.2mmHg and 5.4 +/- 0.6 mmHg. Pranidipine reduced LVEDP and CVP to 13.6 +/- 1.4mmHg (P < 0.01) and 2.5 +/- 0.4mmHg (P < 0.01). The weight of the left and right ventricles in MI was significantly higher than in the sham-operated rats (sham, 2.02 +/- 0.04 and 0.47 +/- 0.02g/kg; MI, 2.18 +/- 0.05 and 0.79 +/- 0.04g/ kg; P < 0.01). Left ventricular end-diastolic dimension (LVDd) in MI increased to 10.3 +/- 0.3mm (P < 0.01) (sham, 6.4 +/- 0.3mm). Pranidipine prevented an increase in the weight of the left and right ventricles (2.02 +/- 0.04 and 0.6 +/- 0.03g/kg, P < 0.01) and LVDd (7.9 +/-0.2mm, P < 0.01 to MI). Plasma renin activity (PRA), and plasma epinephrine, norepinephrine, and dopamine concentrations in MI were higher than those of the sham-operated rats. Pranidipine decreased the PRA and plasma cathecolamine levels of the myocardial infarcted rats to the level of the sham-operated rats. Moreover, the rats in MI showed systolic dysfunction, shown by decreased fractional shortening (sham, 31 +/- 2% vs MI, 15 +/- 1%; P < 0.01) and diastolic dysfunction shown by the E-wave deceleration rate (sham, 12.8 +/- 1.1 m/s2; MI, 32.6 +/- 2.1 m/s2; P < 0.01). Pranidipine significantly prevented systolic and diastolic dysfunction. The increases in beta-myosin heavy chain (MHC), alpha-skeletal actin, and atrial natriuretic polypeptide mRNAs in the noninfarcted left ventricle and right ventricle at 4 weeks after the myocardial infarction were significantly suppressed by the treatment with pranidipine. On the other hand, depressed alpha-MHC was restored to normal levels by pranidipine in both regions. In conclusion, pranidipine prevents the left ventricular remodeling process accompanied by systolic and diastolic dysfunction, and inhibits abnormal cardiac gene expression after myocardial infarction.

Ornithine decarboxylase activity in the non-cancerous hepatic tissue of patients with hepatocellular carcinoma

BACKGROUND/AIMS

Hepatocellular carcinoma may develop in patients with chronic hepatitis and cirrhosis. Active hepatitis is an important etiologic factor in the development of hepatocellular carcinoma. We measured ornithine decarboxylase activity, an important enzyme during cell proliferation, in non-cancerous hepatic tissue in patients with hepatocellular carcinoma.

METHODOLOGY

Thirty-four patients who underwent liver resection for hepatocellular carcinoma were the subjects of this study. Hepatitis B surface antigen was detected in 7 patients (HBV group) and hepatitis C virus antibody was detected in 27 patients (HCV group). Tissue ornithine decarboxylase activity was measured. Histologic severity in active hepatitis (activity score) and degree of fibrosis (staging score) were determined.

RESULTS

Ornithine decarboxylase activity was significantly higher in the HCV group than in the HBV and control groups. In all patients, ornithine decarboxylase activity correlated directly with the histologic activity score and the histologic staging score. In the HCV group, ornithine decarboxylase activity correlated with the histologic activity score.

CONCLUSIONS

Ornithine decarboxylase activity in non-cancerous hepatic tissue correlated with the severity of active hepatitis and degree of fibrosis. In patients with hepatitis C virus, active hepatitis with increased ornithine decarboxylase activity is an important factor in the development of hepatocellular carcinoma.

Biochemical markers and bone mineral density in patients with hip fractures in men

The purpose of this study was to determine whether males with hip fractures have associated decreased gonadal function. Second void urine and serum samples were obtained from 25 male hip fracture patients (mean age+/-SD, 78.5+/-5.9 years) and 19 age- and gender-matched controls (77.6+/-6.2 years). Serum levels of luteinizing hormone (LH), total testosterone (Te), total estradiol (E2), dehydroepiandrosterone sulfate (DHEAS), 1,25(OH)2D3, N-mid osteocalcin (OC(N-mid)), type I collagen degradation products (S-CTx) and urinary levels of pyridinoline (Pyr), deoxypyridinoline (Dpyr) and type I collagen degradation products (U-CTx) were measured. Bone mineral density (BMD) of the L2-4 spine, femoral neck, trochanter, Ward's triangle, distal one third portion of the radius and ultradistal radius were also measured in the fracture group. Serum levels of LH, E2, Te, DHEAS, 1,25(OH)2D3 and OCN-mid in the fracture group were not statistically different from those in the control group. Levels of urinary Pyr, CTx and S-CTx in the fracture group increased significantly compared with those in the control group. In the fracture group, serum levels of Te correlated positively with distal one third portion of the radius BMD and ultradistal radius BMD. U-CTx and S-CTx correlated negatively with all the BMD measurement sites in the hip region and with the radius BMD. An imbalance between bone resorption and bone formation was evident in male hip fracture patients. However, male patients with hip fractures did not show associated decreased gonadal function in this study.

Evaluation of isolated fractures of the greater trochanter with magnetic resonance imaging

The diagnosis of an isolated fracture of the greater trochanter can be done on routine radiographs, but this may not be the whole story. We evaluated fractures of the greater trochanter of the femur by magnetic resonance imaging (MRI). MR images were obtained within 5 days of the time of clinical presentation. Coronal images were performed on T1- and T2-weighted spin-echo images. Eight elderly patients who were diagnosed as having a greater trochanter fracture on standard radiographs underwent MRI. Three were men aged 62-76 (mean 63.4) years, and five were women aged 80-101 (mean 88.6) years. MRI showed that in seven of the eight cases, the fracture line was observed leading from the greater trochanter towards other trochanter regions. In only one case was the fracture limited to the greater trochanter and corresponded to the line observed on the standard radiographs. We suggest that in cases of greater trochanter fracture with somewhat severe symptoms, MRI should be performed in order to discover the appropriate diagnosis and treatment.

Role of MerT and MerP from Pseudomonas K-62 plasmid pMR26 in the transport of phenylmercury

To investigate the individual role of MerT and MerP encoded by Pseudomonas K-62 pMR26 in the transport of phenylmercury, a series of mutants with a specific point mutation in merT and/or genetic deletion in merP were constructed and transformed into Escherichia coli XL1-Blue. Transport of phenylmercury across the cytoplasmic membrane of E. coli mediated by MerT and MerP was inhibited by NaCN and by cold temperatures. Deletion of merP reduced, but did not completely abolish the C6H5Hg+-hyperuptake and -hypersensitive phenotypes suggesting that transport of phenylmercury into the cytoplasm of E. coli is still occurring. Mutations of the vicinal cysteine residues (Cys24 and Cys25) in the first transmembrane region of MerT to serine caused complete loss of Hg2+-hyperuptake and -hypersensitivity, whereas the mutations did not affect the C6H5Hg+-hyperuptake and -hypersensitive phenotypes. In addition, no additive effect on the C6H5Hg+-hyperuptake and -hypersensitive phenotypes was found, when mutations of the two cysteines in MerT to serine were further introduced in the merP-deleted mutants. These results clearly demonstrated that the vicinal cysteine residues of MerT are not involved in the transport of C6H5Hg+, but indeed are involved in the transport of Hg2+ as previously reported.

Prolongation of canine liver allograft survival by a novel immunosuppressant, FTY720: effect of monotherapy and combined treatment with conventional drugs

BACKGROUND

The immunosuppressive effect and other properties of a novel immunosuppressant, FTY720, have been studied mostly in the experimental transplantation of various extrahepatic organs. In this experiment, we evaluated the antirejection potency and adverse effects of this agent on liver grafts using a canine liver transplantation model.

METHODS

Forty-eight orthotopic liver transplantations were performed by the standard technique under a veno-venous bypass. Liver recipients were divided into two studies: a single-dose study with FTY720 at various doses and a combined dose study with conventional immunosuppressants (cyclosporine or tacrolimus) alone and combined with FTY720. Survival, biochemical and hematological tests, blood levels of immunosuppressants, and postmortem histology were determined.

RESULTS

The median survival of untreated control animals was 9 days, whereas treatment with FTY720 at a dose of 0.1 mg/kg/day prolonged graft survival to 49.5 days. FTY720 at 1 mg/kg/day showed a slight but insignificant prolongation to 16 days, but when the dose was increased to 5 mg/kg/day, the graft was rejected at 10 days. The combination of FTY720, 0.1 mg/kg/day, with a subtherapeutic dose of cyclosporine, 5 mg/kg/ day, prolonged median animal survival from 40 days with cyclosporine alone to 74 days. A combination of FTY720 (0.1 mg/kg/day) with tacrolimus (0.5 mg/kg/ day) compromised animal survival, reducing survival from 83.5 days with tacrolimus alone to 30.5 days due to infectious complication and emaciation by overimmunosuppression. No evident drug-induced side effects were observed.

CONCLUSIONS

FTY720 has a potent immunosuppressive effect when used alone at 0.1 mg/kg/day in canine liver transplantation. FTY720 is a promising candidate for future clinical application in orthotopic liver transplantation.

Effects of selective dopamine D4 receptor blockers, NRA0160 and L-745,870, on A9 and A10 dopamine neurons in rats

Extracellular single-unit activities of dopamine neurons were recorded using chloral hydrate anaesthetized rats. We examined the reversal effects of the selective dopamine D4 receptor blockers, NRA0160 (2-Carbamoyl-4-(4-fluorophenyl)-5-[2-[4-(3-fluorobenzylidene) piperidin-1-yl] ethyl] thiazole) and L-745,870 (3-[[4-(4-chlorophenyl) piperazin-1-yl] methyl]-1H-pyrrolo [2,3-b] pyridine), on dopamine agonists induced inhibition of dopamine neural activity. The firing rates of the substantia nigra pars compacta (A9) and the ventral tegmental area (A10) dopamine neurons were inhibited by methamphetamine (MAP: 1 mg/kg, i.v.) and apomorphine (APO: 40 microg/kg, i.v). NRA0160 dose-dependently reversed the inhibitory effects of MAP and APO on both A9 and A10 dopamine neurons. NRA0160 was more potent in reversing the inhibitory effects of both MAP and APO on A10 than A9 dopamine neurons. L-745,870 failed to reverse the inhibition produced by MAP on A9 and A10 dopamine neurons, whereas L-745,870, at the highest dose used, significantly reversed APO-induced inhibition of A10 but not A9 dopamine neurons. These results suggest that NRA0160 has different electrophysiological profiles on dopaminergic neural activity compared to L-745,870 and may have atypical antipsychotic effects.

Angiotensin blockade inhibits SIF DNA binding activities via STAT3 after myocardial infarction

The in vivo activation of transcription factors, which is important for cell regulation by gene expression, has not been well examined in myocardial infarcted heart. The purpose of this study was to determine whether myocardial signal transducer and activator of transcription (STAT) pathway is activated as sis-inducing factor (SIF) in infarcted heart, and to assess the angiotensin blockade on SIF activity in ischemic and non-ischemic myocardium of rat. Myocardial infarction was made by ligation of the coronary artery in Wistar rats. In electrophoretic mobility shift assay, myocardial SIF DNA binding activities gradually increased and reached to peak at 1 week in infarcted and non-infarcted regions after myocardial infarction. Imidapril and candesartan cilexitil significantly prevented the increase in SIF DNA binding activity in infarcted and non-infarcted regions. This increased SIF DNA complex was supershifted by specific anti-STAT3 antibody, indicating that increased SIF complex at least contained activated STAT3 proteins in myocardial infarcted heart. Furthermore, immunoprecipitation-Western blot analysis revealed that STAT3 of infarcted and non-infarcted regions were tyrosine-phosphorylated at 1 week after myocardial infarction. Imidapril and candesartan cilexitil prevented the increase in phosphorylated STAT3. Thus, the transcriptional activation of STAT3 through AT1 receptor may be partially involved in cardiac remodeling after myocardial infarction.

Forty years of cytochrome P450

The term "cytochrome P450" first appeared in literature in 1962. It was a microsomal membrane-bound hemoprotein without known physiological functions at that time and was characterized by a unique 450-nm optical absorption peak of its carbon monoxide-bound form, which was originally reported as the spectrum of a novel "microsomal carbon monoxide-binding pigment" in 1958. Elucidation of its function as the oxygenase in 1963 triggered a rapid expansion of research on this hemoprotein. Annual numbers of the published papers dealing with cytochrome P450, which were listed in Biological Abstracts, increased from 60 in 1970 to 500 in 1980, 900 in 1990, and 1500 in 1997. Cytochrome P450 is now regarded as the collective name of a large family of hemoproteins, "cytochrome P450 superfamily, "which seems to have diversified from a single ancestral protein to many forms during the course of biological evolution and is distributed widely among various forms of life from animals and plants to fungi and bacteria. Multicellular eukaryotic organisms including animals and plants have about 100 or more P450 genes in their genomes, and those many P450 genes are expressed tissue specifically and developmental stage specifically, indicating their diverse physiological functions. In mammals, various P450s participate in the biosynthesis and metabolism of sterols and steroid hormones and the metabolism of various lipid biofactors including eicosanoids, vitamin D3, and retinoids. Oxidative metabolism of foreign hydrophobic compounds as the first step of their excretion from the animal body is apparently another major function of cytochrome P450, which protects animals from noxious foreign compounds, man-created and natural.

Intracellular pathways of V(1) and V(2) receptors activated by arginine vasopressin in rat hippocampal neurons

To explore the intracellular pathways activated by vasopressin receptors, the effects of arginine vasopressin (AVP) and its analogues mediating glycine (Gly)-induced Cl(-) currents (I(Gly)) were examined in acutely dissociated rat hippocampal CA1 neurons using the whole-cell patch recording technique. AVP and its analogues inhibited I(Gly) in a concentration-dependent manner. The inhibitory actions of AVP(4-9) (AVP metabolite) and NC-1900 (AVP(4-9) analogue) were reversed by a V(1) receptor antagonist, or pretreatment with 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N', N'-tetraacetic acid. In contrast, these blocking procedures had no effect on the 1-desamino-8-D-AVP (DDAVP; V(2) agonist) action. A V(2) receptor antagonist did not block the inhibitory action of AVP(4-9) or NC-1900, but blocked that of DDAVP. The inhibitory action of AVP was completely blocked by the co-application of the V(1) and V(2) antagonists. The inhibitory action of NC-1900 was not affected by perfusion with a Ca(2+)-free external solution, but was strongly blocked by thapsigargin. The intracellular application of heparin or anti-inositol 1,4,5-triphosphate (IP(3)) also blocked the NC-1900 action. Furthermore, Ca(2+)/calmodulin (CaM) inhibitors blocked the NC-1900 action, while a CaM-dependent kinase II inhibitor and PKC modulators had no effect. 2',5'-Dideoxyadenosine (an adenylate cyclase inhibitor), H-89, and Rp-cAMPS blocked the inhibitory actions of NC-1900 and DDAVP. These results suggest that the activation of the V(1) receptor in the hippocampal neurons induces the production of IP(3), which releases Ca(2+) from the IP(3)-sensitive Ca(2+) storage sites. The Ca(2+) binds to CaM, resulting in the activation of Ca(2+/)CaM-sensitive adenylate cyclases. The activation of protein kinase A through the adenylate cyclase inhibits I(Gly).

Rapid kinetic studies of electron transfer in the three isoforms of nitric oxide synthase

The nitric oxide synthases (NOSs) consist of a flavin-containing reductase domain, linked to a heme-containing oxygenase domain, by a calmodulin (CaM) binding sequence. The flavin-containing reductase domains of the NOS isoforms possess close sequence homology to NADPH-cytochrome P450 reductase (CPR). Additionally, the oxygenase domains catalyze monooxygenation of L-arginine through a cytochrome P450-like cysteine thiolate-liganded heme bound in the active site. With these considerations in mind, we conducted studies in an attempt to gain insight into the intermediates involved in flavoprotein-to-heme electron transfer in the NOSs. Static, steady-state, and stopped-flow kinetic studies indicated that nNOS must be reduced to a more than one-electron-reduced intermediate before efficient electron transfer can occur. Therefore, the possibility exists that the oxygenase domains of the NOS isoforms may receive their electrons from the reductase domains by a mechanism resembling the CPR-P450 interaction. Furthermore, the rate-limiting step in electron transfer appears to be the transfer of electrons from the flavoprotein to the oxygenase domain facilitated by the binding of CaM at increased intracellular Ca(2+) concentrations. Thus, modulation of electron transfer rates appears to be regulated at the level of the flavoprotein domains of the NOS isoforms.

Increased JNK, AP-1 and NF-kappa B DNA binding activities in isoproterenol-induced cardiac remodeling

The in vivo signal transduction pathway, responsible for isoproterenol-induced cardiac hypertrophy or remodeling, remains to be clarified. The purpose of this study was to examine c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), activator protein-1 (AP-1) and nuclear factor-kappa B (NK-kappa B) DNA binding activity, which seem to be important in a signal transduction cascade upstream of the increased level of mRNA expression observed in isoproterenol-induced cardiac remodeling. Rats were continuously infused with saline and isoproterenol by intravenous injection (a short period; 0.5 microgram/kg/min) and an osmotic minipump (a long period; 0.5 or 3 mg/kg/day). Cardiac morphology was measured by echocardiography. JNK and ERK were measured by in gel kinase assay. AP-1 and NF-kappa B DNA binding activity was determined using an electrophoretic mobility shift assay. Echocardiogram showed that the thickness of the left ventricular anterior wall (AW) and left ventricular posterior wall (PW) increased at day 1 in low doses, and at day 1 in high doses. Isoproterenol significantly increased ERK and JNK activity at 15 min after intravenous infusion of 0.5 microgram/kg/min isoproterenol. At late phase about JNK and ERK activity, only a high dose of isoproterenol increased JNK. AP-1 DNA binding activities spurred by low or high doses of isoproterenol administration increased at 12 h, reached their peak of 24.1- and 37.1-fold (P < 0.01), respectively, at 24 h, and thereafter decreased. Although low doses of isoproterenol did not change the level of NF-kappa B DNA binding activities, high doses increased it to 10.9-fold (P < 0.01) at day 2. This study showed increased JNK, ERK, AP-1 and NF-kappa B DNA binding activities in isoproterenol-induced cardiac remodeling. AP-1 may contribute to the isoproterenol-induced cardiac remodeling, and JNK or NF-kappa B may also play some roles in it.

In vivo and in vitro phosphorylation of rice dwarf phytoreovirus Pns12 cytoplasmic nonstructural protein

In vivo and in vitro phosphorylation and intracellular location of rice dwarf phytoreovirus Pns12, which is encoded by one of the twelve dsRNA genome segments, S12, and comprises 312 amino acids, was investigated. When [32P]phosphoric acid was incorporated into RDV-infected leafhopper cultured cells, labelled Pns12 was immunoprecipitated from the cells by a monospecific anti-Pns12 polyclonal antibody. Recombinant Pns12 was purified from Spodoptera frugiperda cells infected with AcRS12, a baculovirus recombinant carrying a full-length cDNA of RDV S12. Purified Pns12 was also demonstrated to be phosphorylated in vitro by a kinase activity present in host (rice, barley, wheat, leafhopper) cells and non-host (tobacco, spinach, white clover, S. frugiperda, mosquito, mammals) cells as well. Immunocytochemical studies showed Pns12 accumulated in the cytoplasm of infected cells, and frequently localized in a slightly electron-dense patch. These results demonstrated that RDV Pns12 was a cytoplasmic nonstructural phosphoprotein.