Na+ channel block prevents the ischemia-induced release of norepinephrine from spinal cord slices

The principal finding of the present study with rat spinal cord slices was the novel demonstration of the [Ca2+]o-independent effect of ischemia on norepinephrine release and its antagonism by tetrodotoxin and low temperature (10 degrees C). Our finding that tetrodotoxin antagonized the effects of glucose deprivation on norepinephrine release in a [Ca2+]o-independent way suggests that Na+ channel block alone, i.e., the prevention of Na+ accumulation, may account for the protective action. Low temperature completely prevented the effect of ischemia on norepinephrine release but did not change the release associated with axonal activity. This finding is in good agreement with the observation that small changes in brain temperature critically determine the extent of neuronal injury from ischemia and suggests that both [Ca2+]o-independent release and cell injury are associated with the norepinephrine membrane carrier. It is suggested, therefore, that drugs able to attenuate the increase in [Na+]i during ischemia may be useful agents to protect against ischemic damage if given before the insult.

Expression of mRNA coding for four catecholamine-synthesizing enzymes in human adrenal pheochromocytomas

OBJECTIVE

To understand the molecular mechanisms by which catecholamine synthesis is controlled in pheochromocytomas--tumors that synthesize and release catecholamines, which are related to various clinical manifestations of the condition.

METHODS

We measured the concentrations of mRNA coding for the catecholamine-synthesizing enzymes tyrosine hydroxylase, aromatic L-amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyl transferase (PNMT) and for the catecholamine contents in 12 pheochromocytomas and 12 normal adrenal medullas.

RESULTS

The mean content of total catecholamine and the beta-actin mRNA expression in the pheochromocytomas were almost the same as those in the normal adrenal medullas. However, the tyrosine hydroxylase, AADC and DBH mRNA concentrations in the pheochromocytomas were greater than those of the normal adrenal medullas. Conversely, the PNMT mRNA concentration in the pheochromocytomas was lower than that in the normal adrenal medullas. These differences are responsible for the difference in the proportions of catecholamines between pheochromocytomas and normal adrenal medullas. The constitutive expression of the catecholamine-synthesizing enzyme mRNAs varied in magnitude among the pheochromocytomas, and the tyrosine hydroxylase mRNA expressions correlated with the contents of total catecholamine in the tumors (r=0.964, P<0.0001).

CONCLUSIONS

These findings indicate that catecholamine production in pheochromocytomas is primarily controlled by the level of gene expression.

[A case of advanced gastric cancer successfully treated by UFT and CDDP followed by surgical resection proving cancer cell disappearance in the stomach]

A patient with advanced gastric cancer responded remarkably to UFT combined with CDDP. UFT was administered orally for 28 consecutive days at a dose of 400 mg/m2, and CDDP was injected intravenously for a day at a dose of 100 mg/m2. Surgical resection proved the histological disappearance of cancer cells in stomach.

Serum levels of five tumor markers for lung cancer in patients with chronic renal failure

The soluble cytokeratin 19 fragment (CYFRA) and pro-gastrin-releasing peptide (ProGRP) are recently described promising tumor markers for lung cancers. To assess their alterations in renal dysfunction, serum levels of CYFRA and ProGRP were determined together with conventional markers including carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC), neuron specific enolase (NSE) in patients with renal failure of varying degrees. The mean concentration of all these markers but NSE significantly increased with the severity of renal failure. After hemodialysis (HD), the mean concentration of ProGRP, the molecular weight of which is comparable to that of 2-microglobulin, was significantly decreased. High false positive rates for tumor markers of lung cancer in patients with renal failure should be considered to avoid unnecessary diagnostic procedures.

Asymmetrical changes in the fodrin alpha subunit in the superior temporal cortices in schizophrenia

BACKGROUND

We examined possible abnormalities in neural structural proteins that may underlie morphometric changes reported in the left superior temporal cortices (Brodmann's area 22) of schizophrenics.

METHODS

Particulate proteins of the superior temporal cortices taken at autopsy from 11 schizophrenic and 9 control brains were fractionated by gel electrophoresis. Target proteins, identified by reading their amino acid sequences, were immunoquantified using the specific antibody.

RESULTS

Amino acid sequences of the 150-kDa proteins on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, which were significantly increased on the left side of schizophrenic superior temporal cortices, revealed that they were proteolytic fragments of the alpha subunit of fodrin, a major cytoskeletal protein underlying the plasma membrane. Immunoquantification using the specific antibodies against alpha and beta subunits of fodrin indicated that there exist concomitant decreases in the full-length 240-kDa form and increases in the 150-kDa form of alpha-fodrin with no changes of the 235-kDa form of beta-fodrin in the left superior temporal cortices of the schizophrenic brains.

CONCLUSIONS

The findings may be a possible molecular basis for linking morphometric changes to neurochemical pathophysiology in schizophrenia.

[Genetic polymorphism of human CYP2E1: new allels detected in exons and exon-intron junctions]

Cytochrome P450-2E1 (CYP2E1) is a major component of the microsomal ethanol-oxidizing system (MEOS) and is also involved in the metabolism of a variety of foreign compounds including carcinogens. It has been shown that there is an interindividual variation in the expression of human hepatic CYP2E1. Gene-environmental interactions have been suggested to account for the difference. In this study, we screened nine exons of the human CYP2E1 gene for detecting allelic variants in genomic DNA samples obtained from 115 Japanese controls, 96 Japanese alcoholics and 124 American control subjects. A novel missense mutation in exon 2 (V72L) was found in Japanese controls, and another missense mutation in exon 8 (D394G) was detected in American Caucasians. In addition, two novel silent mutations in exon 6 (T303T) and exon 8 (F420F) were found in Japanese controls and alcoholics. Especially the silent mutation in exon 8 was highly polymorphic among three population groups. The mutation in exon 2 (V72L) was detected only in Japanese controls, but not in alcoholics although it shows no significant difference. Gene frequency of the silent mutation in exon 8 was significantly higher in Japanese than American Caucasians (34.8% vs 21.0%, p < 0.02). Our data indicated that nucleotide replacement in the open reading frame is no major factor responsible for alcoholism. However, functional significance of the two novel missense mutations remains to be detailed.

Importance of microperineural invasion as a prognostic factor in ampullary carcinoma

BACKGROUND

This was a study of the relation of clinicopathological factors to prognosis in 25 patients who had ampullary carcinoma resected.

METHODS

The 5-year survival rate was six of the 25 patients. The presence of microperineural invasion was sought and related to outcome.

RESULTS

Factors relating to prognosis included tumour gross appearance, diameter, pancreatic invasion and microperineural invasion. The 5-year survival rate of 14 patients with microperineural invasion was 3, significantly worse than the 7 in 11 without invasion (P = 0.002, univariate analysis). By multivariate analysis, microperineural invasion was the most important prognostic factor (P = 0.02). Type of tumour recurrence was similar to that in pancreatic carcinoma.

CONCLUSION

Pancreaticoduodenectomy, rather than local resection, is the procedure of choice in patients with ampullary carcinoma.

Importance of microperineural invasion as a prognostic factor in ampullary carcinoma

BACKGROUND

This was a study of the relation of clinicopathological factors to prognosis in 25 patients who had ampullary carcinoma resected.

METHODS

The 5-year survival rate was six of the 25 patients. The presence of microperineural invasion was sought and related to outcome.

RESULTS

Factors relating to prognosis included tumour gross appearance, diameter, pancreatic invasion and microperineural invasion. The 5-year survival rate of 14 patients with microperineural invasion was 3, significantly worse than the 7 in 11 without invasion (P = 0.002, univariate analysis). By multivariate analysis, microperineural invasion was the most important prognostic factor (P = 0.02). Type of tumour recurrence was similar to that in pancreatic carcinoma.

CONCLUSION

Pancreaticoduodenectomy, rather than local resection, is the procedure of choice in patients with ampullary carcinoma.

Fast imaging of the second moment using magic echo trains

Approaches are discussed to imaging of the second moment of proton NMR dipolar spectra. Two methods are proposed using the peak shapes of the magic echo trains for evaluation of the second moment. One is a quasi-multidimensional FT approach where the peak shapes of the magic echoes are spatially resolved, and the other is the fast version of the former approach, collecting the same data in a much shorter measurement time. Preliminary results of spatially 2D, as well as 1D, experiments are reported.

Expression of optical diffusion coefficient in high-absorption turbid media

The optical diffusion coefficient in a homogeneous turbid medium with high absorption was determined by steady-state measurements of the light transmission under the infinite-boundary condition. The intensity of the transmission was well described by the solution of the optical diffusion equation. Moreover, the optical diffusion coefficient D was given by a constant, (3 mu'(s))-1, where mu'(s) is the reduced scattering coefficient, up to the absorption coefficient of about 0.3 mu'(s). These results mean that attenuation by absorption only contributes to exponential attenuation along the optical path defined by the scattering coefficient and geometry of the system even in high-absorption turbid media such as the pathological living tissues of bleeding or haematoma.

An in vitro 1H-MRS model of oncogene transfection. The spectral feature of c-erbB-2 and c-Ha-ras transfected NIH3T3 fibroblast cells

PURPOSE

Malignancy is an abnormality of cell division and differentiation based on abnormal expression of oncogenes. This note describes the in vitro 1H-NMR spectral features of oncogene-transfected NIH3T3 fibroblast cells compared to non-transfected cells.

MATERIAL AND METHODS

1H-NMR spectra of cultured NIH3T3 cells and c-erbB-2 or c-Ha-ras gene-transfected cells were obtained by 400 MHz high resolution NMR. The peaks were assigned by 2D HOHAHA spectra of the cell suspension and the spectral changes were evaluated in 1D and 1D differential spectra.

RESULTS

The 1H spectra obtained from both transfected cell lines were broadened over all peaks, suggesting reduced mobility in plasma membrane lipid molecules. No other differential spectra for characterizing metabolic change was detected.

CONCLUSION

Broadened 1H spectra observed after c-erbB-2 or c-Ha-ras transfection suggest changes of plasma membrane viscosity, which may be related to the oncogene expression.

Synthesis of asymmetrically labeled sucrose by a recombinant sucrose synthase

About 80% of radioactivity was recovered in asymmetrically labeled sucrose from UDP-[14C]glucose or [14C]fructose with recombinant mung bean sucrose synthase expressed in Escherichia coli harboring pEB-01. This high recovery is due to the fact that the enzyme conserving the activity of sucrose synthase has a similar affinity for UDP-glucose and fructose to an intact enzyme from the mung bean, but a lower affinity for sucrose.

A beta-glucosidase gene downstream of the cellulose synthase operon in cellulose-producing Acetobacter

An open reading frame was found 214 bp downstream of the cellulose synthase operon of Acetobacter. The encoded amino acid sequence was found to be similar to some beta-glucosidases (G3ases). We detected G3ase activity in the culture medium and analysis of the N-terminal amino acid sequence showed that this gene encodes the enzyme. Therefore, it is possible that this region is a gene cluster for cellulose synthesis.

Effect of oxidized low density lipoprotein on thrombomodulin expression by THP-1 cells

We have investigated the effects of oxidized low density lipoproteins (oxidized LDL) on the expression of TM by THP-1 monocytic cells. TM antigen levels and its cofactor activity for thrombin-dependent protein C activation were increased by oxidized LDL and accompanied by an increase in TM mRNA levels. Incubation of THP-1 cells with 300 microg/ml oxidized LDL for 24 h resulted in an 80% increase of cellular TM antigen levels. Native LDL and acetylated LDL did not affect the TM expression by these cells. The resultant aqueous phase after extraction of oxidized LDL by chloroform/methanol increased the TM antigen levels as well as oxidized LDL. Phorbol 12-myristate 13-acetate (PMA) also increased the TM antigen level 2.1 times the control and was accompanied by the adhesion of cells to plastic dishes and increasing macrophage cell surface antigen CD14 levels. In contrast, oxidized LDL did not induce differentiation to the macrophage. The present results indicate that oxidized LDL increases cellular TM antigen without cellular differentiation and that up-regulation of TM by oxidized LDL in monocytes may have some implication in atherosclerosis.

Expression and characterization of sucrose synthase from mung bean seedlings in Escherichia coli

The cDNA fragment coding for mung bean (Vigna radiata Wilczek) sucrose synthase was introduced into the expression vector pET-20b resulting in the construction of plasmid pEB-01. After transformation of Escherichia coli strain BL21(DE3) cells by pEB-01 and induction with isopropyl thio-beta-galactoside, high level expression of the recombinant enzyme was obtained. The enzyme had a tetrameric form that conserved the activity of sucrose synthase. Although the Km and Vmax of the recombinant enzyme acting on either UDP-glucose or fructose were very close to those of the native enzyme isolated from mung bean seedlings, the Km for sucrose was higher by a factor of 10 for the recombinant enzyme. This suggests that the recombinant sucrose synthase has a tendency to synthesize sucrose, although the native enzyme catalyzes a freely reversible reaction.

[Use of BiPAP during weaning from mechanical ventilation in a patient with chronic obstructive pulmonary disease and acute respiratory failure]

In a 65-year-old man with chronic obstructive pulmonary disease and acute respiratory failure, bi-level positive airway pressure device (BiPAP) was used as part of weaning from mechanical ventilation. As an outpatient, he had had dyspnea of grade V (Hugh-Jones) and was hypercapnic (PaCO2 of 70 torr) and hypoxemic (PaO2 of 60 torr), while he was receiving oxygen at 2 L/min via nasal cannula. Acute respiratory failure developed due to pneumonia, and mechanical ventilation was begun. However, he could not be weaned with a standard weaning technique (T-piece). On the fifth day of mechanical ventilation, he was extubated and treatment with BiPAP was begun. He did not complain of dyspnea even though PaCO2 did not decrease, which indicates that BiPAP reduced the work of breathing. Use of BiPAP might make reintubation unnecessary when acute ventilatory failure develops soon after extubation in patients with COPD.

Inhibitory effects of glibenclamide and pertussis toxin on the attenuation of ischemia-induced myocardial acidosis following ischemic preconditioning in dogs

Ischemic preconditioning is known to be mediated by several humoral factors, such as adenosine, norepinephrine, and bradykinin. We examined intracellular signal transduction of ischemic preconditioning following receptor stimulation. Alterations in the pH of the ischemic bed were monitored to assess the response of control and ischemic-preconditioned myocardium to glibenclamide and pertussis toxin. Pentobarbital-anesthetized open-chest dogs were subjected to 40 min of ligation of the left anterior descending coronary artery. Ischemic preconditioning was elicited by 25-min periods of coronary ligation followed by 5 min of reperfusion before a 40-min period of ligation. Glibenclamide (0.3 mg/kg)was given i.v. 20 min before the onset of ischemic preconditioning. Pertussis toxin (6-10 micrograms/kg) was given i.v. 3 days before the experiment. Tissue myocardial pH was measured by a glass micro-pH electrode. Ischemia for 5 min decreased myocardial pH and reperfusion returned it to the preischemic levels. Ischemia for 40 min decreased the myocardial pH from 7.43 +/- 0.06 to 6.43 +/- 0.08. Ischemic preconditioning significantly attenuated the decrease in myocardial pH (6.57 +/- 0.06) induced by 40 min of ischemia. Pretreatment with either glibenclamide or pertussis toxin completely abolished the effect of ischemic preconditioning on ischemic myocardial acidosis. Ischemic preconditioning can attenuate ischemia-induced myocardial acidosis in dogs, and this effect is mediated by activation of adenosine triphosphate-sensitive potassium channels and pertussis toxin-sensitive guanosine triphosphate-binding protein.

1 alpha,25-dihydroxyvitamin D3 induces very low density lipoprotein receptor mRNA expression in HL-60 cells in association with monocytic differentiation

Expression of VLDL receptor mRNA during differentiation of HL-60 cells was investigated by Northern analysis. The expression induced in 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3)-treated cells was 3 times that in untreated cells, while LDL receptor mRNA expression was unchanged. VLDL receptor mRNA levels were not changed in macrophages caused to differentiate from HL-60 cells by treatment with phorbol 12-myristate 13-acetate (PMA). Treatment of sarcoma cells which possess the vitamin D receptor (MG-63 cell line) with 1 alpha,25(OH)2D3 did not affect VLDL receptor mRNA levels. Therefore, 1 alpha,25(OH)2D3 induces VLDL receptor mRNA in HL-60 cells through differentiation-dependent mechanisms.

Pharmacological characterization of endothelin-induced rat pulmonary arterial dilatation

1. The aim of study was to characterize endothelin (ET)-induced vasodilation in isolated extrapulmonary rat arteries (EPA) and in intrapulmonary arteries (IPA) preconstricted with 1 microM phenylephrine. 2. The ET-3 (1 nM-100 nM)- and ET-1 (10 nM-100 nM)-induced transient vasodilatations in EPA were more potent than those in IPA. The vasodilatation induced by ET-3 (100 nM) was larger than that induced by ET-1 (100 nM). 3. Both the ETB antagonist, BQ788 (3 microM) and or endothelium denudation, but not the ETA antagonist, BQ123 (3 microM), abolished the vasodilation induced by ET-1 or ET-3 (100 nM each) in EPA and in IPA. The ATP-sensitive K + channel blocker, glibenclamide (20 microM) and the nitric oxide synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA, 1 mM) suppressed the ET-induced vasodilatation in EPA and in IPA. 4. We conclude that the vasodilatation induced by endothelins is markedly reduced in rat isolated IPA, and suggest that the endothelial ETB-mediated vasodilatation varies depending on rat pulmonary arterial regions. Furthermore, ETB-mediated vasodilatation involves activation of ATP-sensitive K+ channels and of nitric oxide synthase in rat isolated EPA and IPA.

Limitation of stunning in dog myocardium by nucleoside and nucleotide mixture, OG-VI

OG-VI is a solution composed of 30 mM inosine, 30 mM sodium 5'-guanylate, 30 mM cytidine, 22.5 mM uridine, and 7.5 mM thymidine, expecting to use for total parenteral nutrition. We examined the effect of OG-VI on myocardial contractile dysfunction during reperfusion after ischemia (myocardial stunning) in dogs. Pentobarbital-anesthetized dogs were subjected to 20-min left anterior descending coronary artery ligation followed by 30-min reperfusion. Saline, OG-VI or its constituents [inosine and sodium 5'-guanylate mixture (IG), and cytidine, uridine, and thymidine mixture (CUT)], or 5-amino-4-imidazole carboxamide riboside (AICAr) was infused at 0.1 mL.kg-1.min-1, starting 30 min before the ischemia. The contractile function was determined by ultrasonometry and assessed as % segment shortening (%SS). %SS was markedly decreased by ischemia, and returned toward pre-ischemic level after reperfusion, although the recovery was incomplete. The %SS was almost completely recovered by OG-VI and IG, and to a lesser extent by AICAr; CUT was ineffective. In the presence of 1 mg.kg-1 of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, a selective adenosine A1 receptor antagonist), cardioprotective effect of OG-VI on stunned myocardium was still observed. In conclusion, infusion of OG-VI improved myocardial contractile dysfunction in stunned myocardium. This effect was more potent than its constituents and AICAr. Adenosine A1 receptors are not involved in the mechanism.

Genomic classification of fish nodaviruses by molecular phylogenetic analysis of the coat protein gene

A molecular phylogenetic analysis of 25 isolates of fish nodaviruses, the causative agents of viral nervous necrosis of marine fish, was performed based on the nucleotide sequences (427 bases) of the coat protein gene. These fish nodaviruses were classified into four clusters: tiger puffer nervous necrosis virus, striped jack nervous necrosis virus, berfin flounder nervous necrosis virus, and red-spotted grouper nervous necrosis virus.

[Comparison of three methods for quantitative measurement of hepatitis C virus]

Three assays for measuring hepatitis C virus(HCV) were compared with regard to sensitivity and correlations. The methods included were the Roche Amplicor HCV Monitor test(PCR), the branched DNA signal amplification assay(b-probe), and the serum concentration of HCV core protein measured by the sandwich FEIA (Core-Ag). Also, HCV serotypes were determined by the enzyme-linked immunosorbent assay. Testing 105 consecutive HCV-RNA positive samples showed that the PCR was the most sensitive assay(100% quantifiable), followed by the Core-Ag(82.4%) and the b-probe(75.3%). The values obtained by each method correlated well in serotype 1, whereas some discordance was noted in serotype 2 cases. Also, serotype 2 samples were less quantifiable particularly by b-probe assay than serotype 1 samples. These points have to be considered in quantification of serum HCV levels by currently available these three methods.

Role of platelets in myocardial ischemia-reperfusion injury in dogs

We investigated the involvement of circulating platelets in myocardial ischemia-reperfusion injury in canine autoperfused heart-lung preparations using filters to deplete platelets and/or leukocytes. The left anterior descending (LAD) coronary artery was occluded for 40 min, followed by 40 min reperfusion, in 3 groups: a leukocyte-platelet-depleted (LPD) group, in which both leukocytes and platelets were depleted; a leukocyte-depleted (LD) group, in which leukocytes alone were depleted; and a control group. There were no differences in hemodynamics or arrhythmias among groups before or during coronary occlusion. After reperfusion, the maximum rate of change in left ventricular pressure during systole and diastole was significantly higher in the LPD group than in the control and LD groups. The LPD group also showed gradual recovery of regional myocardial function and a decrease in the frequency of premature ventricular contractions. The LD group showed a slight improvement in cardiac function and arrhythmias compared with the control group. Although there was no significant difference in the pulmonary arterial plasma level of thromboxane B2 at any stage among groups, the control group showed an increase after reperfusion. These results suggest that platelets are important in reperfusion injury and that the depletion of both leukocytes and platelets effectively protects against reperfusion injury.

Pharmacological heterogeneity of constrictions mediated by endothelin receptors in rat pulmonary arteries

The endothelin (ET) receptors mediating rat pulmonary arterial constrictions were investigated. ET-1 and ET-3 constricted both isolated intrapulmonary artery (IPA) and extrapulmonary artery (EPA), with ET-1 having a potency approximately 10 times that of ET-3. The ET(B) selective agonist IRL-1620 produced constriction of only IPA. The ET(B) selective antagonist BQ-788 suppressed the ET-1-induced constriction of IPA only. The ET(A) selective antagonist BQ-123 more effectively antagonized the ET-1-induced constriction of EPA than that of IPA. The combination of BQ-123 and BQ-788 increased the antagonistic response to ET-1 in IPA but not in EPA. Then, large constriction remained in IPA and EPA. The receptor nonselective antagonist PD-145065 almost completely inhibited the ET-1-induced constriction of IPA and EPA. BQ-123 completely inhibited the ET-3-induced constriction of EPA; however, it partially suppressed that of IPA. The combination of BQ-123 and BQ-788 completely inhibited the ET-3-induced constriction of IPA. These results demonstrate that the ET-1-induced constrictions are mediated by both ET(A) and ET(B) in IPA and by ET(A) in EPA. Because of differences in sensitivity to ET receptor antagonists for ET-1- and ET-3-induced constrictions, pharmacological heterogeneity of ET(A) is suggested. Additionally, endothelial denudation affected the ET-3-induced constriction of EPA, but not of IPA, and it didn't affect the response to ET-1. This suggests that the vasodilatory effect of endothelium on ET-3-induced vasoconstrictions varies depending on pulmonary vascular regions.

Effect of a protein phosphatase inhibitor, okadaic acid, on thrombomodulin expression in cultured human umbilical vein endothelial cells

We examined the effects of okadaic acid, a potent specific inhibitor of protein phosphatases 1 and 2A, on the expression of thrombomodulin (TM), a cell surface anti-thrombotic glycoprotein, on cultured human umbilical endothelial cells. Okadaic acid (2.5-10 nM) significantly increased TM antigen levels in parallel with its cofactor activity for thrombin-dependent protein C activation. Incubation of cells with 10 nM okadaic acid for 18 h induced an approximately 240% up-regulation of TM antigen levels that was accompanied by an increase in TM mRNA levels. Co-incubation of cells with okadaic acid and dibutyryl cyclic AMP further increased TM antigen levels. Furthermore, the effect of cAMP on TM expression was augmented by the pretreatment of cells with 10 nM okadaic acid for 18 h. These results provide evidence for the involvement of protein phosphatase in the cellular regulatory mechanisms for TM expression, which is distinct from that by cAMP.

The effect of Cu2+ on rat pulmonary arterial rings

In the current study, Cu2+ was tested for its ability to relax vessels and to accumulate cyclic GMP (cGMP) in rat pulmonary artery employing rat extrapulmonary arterial rings. Cu(2+)-induced relaxation was endothelium and concentration (in the range from 10(-7) to 10(-4) M) dependent. The content of cGMP in the rings was increased 1.7-fold with 10(-4) M Cu2+. NG-Monomethyl-L-arginine abolished both the copper-induced relaxation and the increase in cGMP of rings. Cu2+ and zaprinast, which inhibits phosphodiesterase activity, caused a synergistic increase in cGMP level in the rings, suggesting that Cu2+ enhanced cGMP level through a mechanism different from that of zaprinast, probably as a consequence of elevated accumulation of nitric oxide (NO). The magnitude of vasorelaxation observed due to simultaneous addition of Cu2+ and acetylcholine was additive, not synergistic. Cu2+ did not augment relaxation induced by exogenously added NO donor. These results suggest that Cu2+ elevates NO level in the rings not by prolonging the half-life of NO, but by activation of endothelial nitric oxide synthase and subsequently potentiating the action of NO on vascular tone.

Catheter ablation of canine ventricular myocardium. The use of repetitive short time constant capacitive shocks to increase lesion volume

Arching and barotrauma, seen with high energy DC catheter ablation, are responsible for diffuse cardiac damage and coronary sinus rupture. In six anesthetized dogs, we investigated the effects of an increasing number of short time-constant capacitive shocks on the volume of myocardial damage. Each dog received capacitive shocks of 2 J/kg at 3 sites in the left ventricle. One shock was delivered in 2 dogs, 2 shocks were delivered in 2 dogs and 3 shocks were delivered in 2 dogs. Shock delivery was not accompanied by hemodynamic collapse, sustained ventricular tachycardia or ventricular fibrillation. The dogs were sacrificed at 60 minutes. Mean (SEM) lesion volumes were 195 (39) mm3, 480 (41) mm3, and 595 (110) mm3, respectively. Despite variability in individual volume of damage, there was a significant increase in lesion volume with an increasing number of shocks. There was no evidence of perforation or tamponade. Increasing myocardial damage can be produced using repetitive capacitive shocks. Delivery of 2 shocks produces clinically useful lesions without the adverse effects associated with single high energy shocks. Repetitive capacitive shocks offer a method of increasing lesion volume without increasing energy and thereby without compromising safety.

Pneumonitis during interferon and/or herbal drug therapy in patients with chronic active hepatitis

We report four cases of acute pneumonitis due either to interferon, or a herbal drug, "Sho-saiko-to", or both in combination, in patients with chronic active hepatitis, focusing on its pathogenesis and response to prednisolone therapy. These cases shared common clinical features: fever, dry cough, dyspnoea, hypoxaemia, diffuse infiltrates both on chest radiography and chest computed tomography, restrictive pulmonary functional impairment, and alveolitis on examination of transbronchial lung biopsy, all of which suggest acute interstitial pneumonia. Furthermore, lymphocytosis was observed in association with the dominant CD8+ T-cell subset in bronchoalveolar lavage fluid. A lymphocyte stimulation test using peripheral blood was positive to interferon in one case and to Sho-saiko-to in another. All patients responded to oral prednisolone therapy. Peripheral soluble interleukin-2 receptor levels decreased in parallel with improvement in the clinical course. All patients were free of symptoms with a follow-up of 1-3 yrs. We conclude that interferon- and/or Sho-saiko-to-induced acute pneumonitis may be due to allergic-immunological mechanisms rather than toxicity, and that peripheral levels of soluble interleukin-2 receptor appear to be good markers of disease activity.

Effect of glucose, insulin, and insulin-like growth factor-I on glucose transport activity in cultured rat vascular smooth muscle cells

Glucose transport activity in cultured rat vascular smooth muscle cells (VSMCs) was examined under various concentrations of D-glucose, insulin, and insulin-like growth factor-I (IGF-I). Confluent cultures of VSMCs were incubated with serum-free medium containing 0-25 mmol/l of D-glucose for 24-49 h. The basal rate of 2-deoxyglucose uptake was reduced in association with increasing concentrations of D-glucose. Uptake of 2-deoxyglucose into the cells was linear between 0 and 15 min of incubation regardless of the glucose concentration. The uptake was inhibited by the addition of 10 mumol/l cytochalasin B or 100 mmol/l D-glucose indicating that the effects were mediated by specific integral glucose carriers. The effect of D-glucose was time-dependent and reversible. Insulin increased the uptake of 2-deoxyglucose in a dose-dependent manner, and its effect was dependent on the preincubation dose of D-glucose. Insulin-stimulated uptake was lower in the cells pre-exposed to 25 mmol/l D-glucose than in the cells pre-exposed to concentrations of D-glucose below 5.5 mmol/l. After a long-term incubation with insulin, the insulin-stimulated glucose transport was inhibited. Recovery of glucose transport activity was assessed by incubating cells with D-glucose for 24-48 h to induce desensitization. After a 24 h glucose conditioning, the uptake of 2-deoxyglucose was lower in the cells preincubated with 25 mmol/l glucose than in the cells preincubated with 5.5 mmol/l glucose. The effect of the glucose conditioning was reversible and dependent on the preincubation dose of D-glucose. IGF-I was a more potent stimulator of glucose transport than insulin. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3-kinase), inhibited the uptake of glucose stimulated by insulin or IGF-I in a dose-dependent manner. Our results suggest that D-glucose regulates its own uptake independently of insulin and modulates the ability of insulin to induce insulin resistance in the cultured rat VSMCs. Glucose attenuated the effect of insulin, and led to a progressive decrease in the activity of the glucose transport effector system. Activation of wortmannin-sensitive PI3-kinase may be involved in the signaling pathways of the insulin- and IGF-I-stimulated glucose uptake in VSMCs. This mechanism of insulin resistance may be relevant to the formation of cellular defects in the vascular wall in patients with diabetes mellitus.

Long-term alcohol intake enhances ADP-ribosylation of the multifunctional enzyme, phosphoglucomutase, in rat liver

Adenosine diphosphate (ADP)-ribosylation is a posttranslational protein modification that, in turn, alters several regulatory proteins in mammalian cells. We demonstrated that long-term alcohol intake enhanced the ADP-ribosylation of a 58-kd protein in rat liver plasma membranes. To assess the biological significance of this phenomenon, we partially purified the 58-kd acceptor protein from solubilized rat liver homogenates by two sequential preparative high-pressure liquid chromatographies. Microsequencing revealed that it was phosphoglucomutase (PGM) (EC 5,4,2,2). This enzyme underwent negligible auto ADP-ribosylation, but the ADP-ribosylation was remarkably increased by adding rat liver plasma membranes. The extent of the increase was greater in alcohol-fed rats than in pair-fed controls, suggesting enhanced enzyme activities toward ADP-ribosylation of PGM after chronic alcohol consumption. Several important enzymes are ADP-ribosylated, after which their activities are modified. The results of this study showed that PGM is a novel substrate for ADP-ribosylation in the liver and that the ADP-ribosylation is increased after chronic alcohol consumption. In view of the variety of roles of PGM in the liver (carbohydrate metabolism and Ca2+ homeostasis), specific roles of this modification in terms of the effects of alcohol on hepatocytes may deserve further investigation.