NAD(+)-glycohydrolase from Streptococcus pyogenes shows cyclic ADP-ribose forming activity

NAD(+)-glycohydrolase from Streptococcus pyogenes was purified by successive chromatography on CM Sepharose CL-6B, Sephacryl S-200 HR and hydroxyapatite. The purified enzyme possessed synthesis and hydrolysis activities of cyclic ADP-ribose (cADPR), a newly found second messenger for Ca2+ mobilisation, along with cleavage activity of the ribose-nicotinamide bond in NAD+.

Antihypertensive properties of a new long-acting angiotensin converting enzyme inhibitor in renin-dependent and independent hypertensive models

The antihypertensive properties of a new long-acting, angiotensin-I-converting enzyme (ACE) inhibiting agent, (2S,3aS,7aS)-1-(N2-nicotinoyl-L-lysyl-gamma-D-glutamyl) octahydro-1H-indole-2-carboxylic acid (CAS 116662-73-8, DU-1777), were investigated orally in various experimental models of hypertension in comparison to a standard ACE inhibitor, lisinopril. The hypotensive potency of DU-1777 was not as marked as that of lisinopril in renin-dependent hypertensive models, i.e., two-kidney one-clip renal hypertensive rats (2K-1C RHR) (ED-20mmHg: 3.1 versus 1.0 mg/kg) or two-kidney two-clip renal hypertensive dogs (2K-2C RHD) (ED-20 mmHg: 2.5 versus 1.0 mg/kg), though the actions of the two drugs were both long-lasting and dose-related. When spontaneously hypertensive rats (SHR) were used, however, DU-1777 was as active as lisinopril (ED-20 mmHg: 17.9 versus 13.6 mg/kg). The most distinguishing results with DU-1777 were its hypotensive effects in renin-independent hypertensive models. In contrast to lisinopril, the drug produced a sustained and dose-related hypotensive effect in DOCA salt hypertensive rats (DOCA-HR) and one-kidney one-clip renal hypertensive rats (1K-1C RHR). There exists an inconsistency between the long duration of the agent's hypotensive action in all tested hypertensive models and its short duration of ACE inhibiting activity as demonstrated both in vivo and ex vivo. The sustained antihypertensive action of DU-1777 cannot be reasoned solely with respect to ACE inhibition, suggesting some additional mechanisms of action yet to be defined.

Relative contribution of alpha 1-adrenoceptor blocking activity to the hypotensive effect of the novel calcium antagonist monatepil

Monatepil, a novel calcium antagonist, has alpha 1-adrenoceptor blocking activity; in the present study, we examined the relative contribution of this alpha 1-blocking activity to its hypotensive effect. Monatepil and diltiazem produced dose-dependent hypotensive effects in anesthetized rats with the same potency. Prazosin and monatepil inhibited the L-phenylephrine (L-PE)-induced pressor response, whereas diltiazem scarcely did. The injection of prazosin produced a decrease in blood pressure (BP) in anesthetized rats. The decrease was recovered with angiotensin II (AII) infusion in a dose-dependent manner. We developed a new rat model by first intravenously injecting prazosin and then infusing AII in anesthetized rats. In this model, diltiazem produced the same hypotensive effect as it did in pretreated conditions, although the hypotensive effect of monatepil was attenuated by 20-35% as compared with pretreated conditions. These results suggest that monatepil exerts alpha 1-adrenoceptor blocking action in vivo and 20-35% of the hypotensive effect of monatepil is attributed to its alpha 1-adrenoceptor blocking activity.

NAD(+)-glycohydrolase productivity of haemolytic streptococci assayed by a simple fluorescent method and its relation to T serotype

The ability of haemolytic streptococci to produce NAD(+)-glycohydrolase was investigated by a fluorescent assay. Enzyme production was found in 31 (91%) of 34 group A, 17 (61%) of 28 group C and eight (27%) of 30 group G isolates. The high producers were found in 22 (65%) of group A, one (4%) of group C and none of group G isolates. The high producers of the group A isolates belonged to T-1, T-3, T-4 or T-12 serotype. These results suggest that NAD(+)-glycohydrolase productivity of streptococci is closely related to specific Lancefield's groups or T serotypes.

Genetic heterogeneity in the precore region of hepatitis B virus in hepatitis B e antigen-negative chronic hepatitis B patients: spontaneous seroconversion and interferon-induced seroconversion

To elucidate the relationship between the clinical severity of chronic liver disease and the precore mutations in hepatitis B e antigen (HBeAg)-negative hepatitis B virus (HBV) carriers, mutations were investigated in the precore region of HBV DNA in 20 chronic hepatitis B patients who seroconverted either spontaneously or after the administration of alpha-interferon (IFN), and 5 asymptomatic carriers. The precore mutation with a stop codon at nucleotide 1896 was found in all patients, irrespective of the histology and in all asymptomatic carriers. The second mutation at nucleotide 1899 was found in 40% of cases studied but always followed by the first mutation at nucleotide 1896. The mixed viral infection of precore mutant and wild-type HBV virus was found in 40% of seroconverted cases after IFN treatment and in sera of HBV carriers obtained within a year after the spontaneous seroconversion. These data suggest that the precore mutants prevail over wild-type HBV in all HBeAg-negative HBV carriers within several years after the seroconversion, but their prevalence could not confine the clinical severity of chronic liver disease.

Distribution of genes encoding cholera toxin, zonula occludens toxin, accessory cholera toxin, and El Tor hemolysin in Vibrio cholerae of diverse origins

A large collection of 1154 strains of Vibrio cholerae of diverse origins including serogroups 01 and 0139 and those belonging to the non-01 and non-0139 (non-01:non-0139) serogroups were examined with a battery of DNA probes specific for cholera toxin (CT), zonula occludens toxin (ZOT), accessory cholera toxin (ACE) and El Tor hemolysin (HLY) to determine the distribution of genes among wild strains and to understand the importance of these factors in the pathogenesis of the disease cholera. Among the 01 clinical isolates, the majority of the strains had an intact core region (ctx, zot, ace) and also possessed the hlyA gene. Although rare, strains of 01 with natural deletions of the ctx, zot and/or ace genes were also detected. The absence of the virulence genes comprising the core region and the presence of the hlyA gene dominated the 01 environment, food isolates and the clinical and environmental non-01: non-0139 strains of V. cholerae. All the 0139 strains examined in this study possessed genes located in the core region and the hlyA gene. Among all the virulence-associated genes examined, the hlyA gene was the most conserved genetic element in V. cholerae independent of biotypes and serogroups.

A defined growth medium for Clostridium difficile

Minimal requirements of amino acids and vitamins were determined in chemically defined medium for five strains of Clostridium difficile. Cysteine, isoleucine, leucine, proline, tryptophan and valine were essential amino acids for growth of C. difficile. Arginine, glycine, histidine, methionine and threonine enhanced growth. Biotin, pantothenate and pyridoxine were essential vitamins. A defined medium containing the minimal requirements of amino acids and vitamins produced a rapid and heavy growth which was comparable to that in modified brain heart infusion, a complex medium. Adenine was able to substitute for glycine and threonine, suggesting that the two amino acids may be utilized as precursors of purine nucleotides. The defined medium developed here will assist physiological and biochemical studies on C. difficile.

Assignment of CD38, the gene encoding human leukocyte antigen CD38 (ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase), to chromosome 4p15

CD38 has been used as a phenotype marker of lymphocyte differentiation. Recently, we have demonstrated that cyclic ADP-ribose can be synthesized and hydrolyzed by CD38 and acts as a second messenger in insulin secretion from pancreatic beta-cells. We have mapped the CD38 gene to human chromosome 4p15 by fluorescence in situ hybridization.

Toxin production by Clostridium difficile in a defined medium with limited amino acids

Basal defined medium (BDM) containing vitamins, minerals and seven amino acids--(/L) tryptophan 0.1 g, methionine 0.2 g, valine 0.3 g, isoleucine 0.3 g, proline 0.3 g, leucine 0.4 g and cysteine 0.5 g--which appeared to be essential for good growth of Clostridium difficile was prepared. Addition of glycine 0.2 g/L and threonine 0.4 g/L to BDM produced better growth of strain VPI 10463, and this defined medium was designated minimum amino acid-defined medium (MADM). Production of toxins A and B by strain VPI 10463 in 6 x MADM containing (/L) tryptophan 0.6 g, methionine 1.2 g, valine 1.8 g, isoleucine 1.8 g, proline 1.8 g, leucine 2.4 g, cysteine 0.5 g, glycine 0.2 g and threonine 0.4 g, was much greater than in MADM. Toxin production by 20 C. difficile strains was examined in two defined media--6 x MADM and complete amino acid-defined medium (CADM) containing 18 amino acids--and one complex medium, modified brain heart infusion medium (m-BHI). Simultaneous production of toxins A and B by all test strains was demonstrated in m-BHI and the two defined media. It was also shown that 6 x MADM was generally better than CADM and as effective as m-BHI for stimulating toxin production by 13 strains. This defined medium would be useful for studies on the physiology, metabolism and pathogenicity of C. difficile.

Characterization of phenotypic, serological, and toxigenic traits of Vibrio cholerae O139 bengal

Biochemical and physiological traits of a collection of strains of Vibrio cholerae O139 Bengal isolated from India, Bangladesh, and Thailand showed that these strains formed a phenotypically homogeneous group with identical characteristics that were essentially similar to those of the O1 serogroup. Resistance to 150 micrograms of the vibriostatic agent O/129 (2,4-diamino-6,7-diisopropylpteridine) and Mukherjee's El Tor phage 5 and classical phage IV and the nonagglutinability of the strains with O1 antiserum were the only discernible differences between the O139 and O1 serogroups. Extensive serological characterization further revealed the O139 serogroup to be distinct from the existing 138 serogroups of V. cholerae. Antiserum raised against the O139 serogroup required absorption with the R reference strain CA385 and with the reference strain representing serogroup O22 to remove cross-reacting agglutinins. All of the 223 representative strains of V. cholerae O139 examined hybridized with DNA probes specific for the cholera toxin (CT) gene, zonula occludens toxin gene, and El Tor hemolysin gene but not with the probe specific for the heat-stable enterotoxin gene. The amount of CT present in stool samples of patients infected with the O139 serogroup was higher than that found in stools of patients infected with O1 El Tor, and this echoed findings that the amount of CT produced by O139 strains in vitro was higher than that produced by the O1 El Tor strains. The nucleotide sequences of the genes encoding the A and B subunits of CT of the O139 serogroup were identical to the sequences reported for the CT gene of O1 El Tor. The CT gene of O139 strains could be amplified by using primers developed for detection of the CT gene of the O1 serogroup by a PCR assay, which could also be used to detect the CT gene in stool samples of patients infected with strains of the O139 serogroup.

Cloning and characterization of cDNA encoding rat ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase (homologue to human CD38) from islets of Langerhans

We report the cloning and cDNA sequence of rat CD38, ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase. Rat CD38 is composed of 303 amino acids and shares a high degree of homology with human and mouse CD38. Rat CD38 mRNA is expressed in various tissues including pancreatic islets but not in RINm5F cells.

Inhibitory effect of clentiazem (TA-3090) on platelet aggregation--alone and in combination with aspirin or ticlopidine

Clentiazem (a novel calcium antagonist) and its basic metabolites (MB1-MB7) showed inhibitory effects on collagen-induced platelet aggregation in human platelets. All the basic metabolites (IC50:8-22 micrograms/ml) had much stronger inhibitory effects than clentiazem itself (IC50:53 micrograms/ml), but the acidic metabolites (MA1-MA4) had no inhibitory effects even at 300 micrograms/ml. Other calcium antagonists (diltiazem, verapamil, nicardipine and nimodipine) also showed similar inhibitory effects although nicardipine and nimodipine were less active than the other drugs. The inhibitory effect of clentiazem was enhanced in the presence of aspirin or ticlopidine. Diltiazem and nicardipine also exhibited a similar potentiation of the anti-platelet effect in combination with aspirin or ticlopidine. Clentiazem also inhibited collagen-induced thromboxane B2 production by the platelets, and this inhibition by clentiazem was additively enhanced by the presence of aspirin. When both clentiazem and aspirin were orally administered to rats, platelet aggregation was additively inhibited. These results indicate that a combination therapy with clentiazem plus aspirin or clentiazem plus ticlopidine may be useful for the prevention and/or treatment of thrombotic disorders.

Preventive effect of monatepil on thromboxane A2 agonist-induced myocardial ischemia in rats

Antianginal effects of monatepil ([(+-)-N-(6,11-dihydrodibenzo[b,e]thiepin-11-yl)-4-(4-fluor ophenyl)-1-piperazinebutanamide]monomaleate, AJ-2615, CAS 10337-41-9), a new calcium antagonist, were evaluated in experimentally induced myocardial ischemia in anesthetized rats and compared with those of diltiazem. Ischemic electrocardiogram change (ST elevation) and reduction of myocardial tissue oxygen tension were induced by intracoronary arterial administration of U-46619 ((5Z,9a,11a,13E,15(S))-9,11-(methano-epoxy)prosta-5,13-di en-1-oic acid) (10 micrograms/kg), a stable thromboxane A2 agonist. The ST elevation induced by U-46619 was significantly prevented by monatepil pretreatment (0.1 mg/kg i.v.), and to a lesser extent by diltiazem (0.3 mg/kg i.v.). Moreover, the decrease in myocardial tissue oxygen tension at the time of ST elevation after U-46619 was inhibited by monatepil pretreatment (0.3 mg/kg i.v.). These results indicate that monatepil exerts a more potent preventive effect against U-46619-induced myocardial ischemic changes than diltiazem and suggest that monatepil has potential for treating vasospastic angina.

[Pharmacological study of ebastine, a novel histamine H1-receptor antagonist]

The anti-allergic activity of ebastine, a novel antihistamine, was assessed in comparison with several antihistamines. 1) Orally administered ebastine dose-dependently inhibited 7-day homologous passive cutaneous anaphylaxis (PCA), experimental allergic rhinitis and experimental asthma in guinea pigs or rats (ED50-values were 2.17, 0.29 and 0.35 mg/kg, respectively); and its anti-allergic activity was more potent than those of terfenadine and mequitazine. Moreover, its PCA-inhibitory activity was still observed 24 hr after the administration. 2) Orally administered ebastine also inhibited histamine-induced skin reaction in rats (ED50: 1.10 mg/kg). 3) In isolated guinea pig trachea, ebastine had no effect on histamine-induced contraction, but carebastine, a main metabolite of ebastine, inhibited this contraction (IC50: 0.12 microM). 4) Carebastine (30-100 microM) suppressed the histamine release from rat peritoneal mast cells and human basophils. 5) Ebastine at a high oral dose showed slight inhibition of the specific binding of 3H-mepyramine to the histamine H1-receptor in rat brain. This binding-inhibitory activity of ebastine was little more potent than that of terfenadine, but much less potent than those of mequitazine and ketotifen. These results indicated that ebastine has potent and long acting anti-allergic activity with few side effects based on the antihistaminic activity in the central nervous system. Furthermore, it was suggested that these effects of ebastine are due to the action of a main metabolite, carebastine.

Evidence against a significant implication of carbonic anhydrase inhibitory activity of zonisamide in its anticonvulsive effects

To clarify whether the inhibitory effect of zonisamide (Excegran, CAS 68291-97-4) on carbonic anhydrase contributes to its anticonvulsant activity, the anticonvulsant activity of 7-methylated zonisamide, a zonisamide analogue which has the same potency of activity as zonisamide in inhibiting carbonic anhydrase in vitro, has been examined. The study using mice did not reveal 7-methylated zonisamide to have any anticonvulsant activity even though its brain concentration level was more than two times the minimal effective concentration of zonisamide. These findings indicate that the anticonvulsant effect of zonisamide is derived from a mechanism(s) other than inhibition of carbonic anhydrase.

Effects of the new calcium antagonist monatepil on cardiac function and myocardial oxygen supply and demand in animals

The effects of monatepil ([(+/-)-N-(6,11-dihydrodibenzo[b,e]thiepin-11-yl)-4-(p-fluor ophenyl)-1- piperazinebutyramide]maleate, AJ-2615, CAS 103377-41-9), a new calcium antagonist, on cardiac function and myocardial oxygen supply and demand were examined. 1. Monatepil reduced the spontaneous beats of isolated rabbit atria at the concentration of 3 x 10(-6) and 10(-5) mol/l. Monatepil decreased the contractile force of papillary muscles in a concentration-dependent manner (3 x 10(-8)-10(-5) mol/l). 2. Monatepil (0.3 mg/kg i.v.) slightly decreased heart rate in anesthetized open-chest dogs. This drug (0.1, 0.3 mg/kg i.v.) increased cardiac output and decreased blood pressure and total peripheral resistance. Monatepil decreased left ventricular dP/dtmax and slightly increased left ventricular end-diastolic pressure. 3. Monatepil (0.1-1.0 mg/kg i.v.) did not affect the PR interval, QRS duration and QTc interval of electrocardiograms in anesthetized dogs, whereas diltiazem (0.3 and 1.0 mg/kg i.v.) markedly prolonged the PR interval. 4. Monatepil (0.1-0.3 mg/kg i.v.) increased coronary blood flow (CoBF) and decreased myocardial oxygen consumption (MOC) and extraction. 5. Monatepil and diltiazem showed almost the same effects on cardiac function and myocardial oxygen supply and demand, but the negative chronotropic and negative dromotropic effects of monatepil were less potent than those of diltiazem.

Possible involvement of endothelin in thromboxane A2 receptor agonist (U-46619)-induced angina in the rat

The thromboxane A2 receptor agonist, U-46619 ((5Z, 9 alpha, 11 alpha, 13E, 15(S))-9,11-(methanoepoxy)prosta-5,13-dien-1-oic acid) (10 micrograms/kg), induced a typical ischemic change (ST elevation) in the electrocardiogram on intracoronary arterial administration in the rat. The elevation of the ST segment induced by U-46619 was significantly reduced by pretreatment with anti-endothelin-1 rabbit serum. The plasma concentration of endothelin-1 dose dependently increased at the time of ST segment elevation after U-46619. These results indicate that endogenous endothelin-1 partly contributes to coronary spasmodic angina induced by thromboxane A2 in rats.

Purification and some properties of a Vero toxin 2 (Shiga-like toxin II) variant (SLT-IIva) of Escherichia coli isolated from infantile diarrhea

A variant of Vero toxin 2 (VT2), or Shiga-like toxin II (SLT-II) was purified from a cloned strain of Escherichia coli carrying a gene that encodes SLT-IIva, which is most closely related to SLT-IIv (VT2vp, VTe) in its nucleotide sequence. The purified SLT-IIva showed a slight difference from the purified SLT-IIv (VT2vp) in mobility on polyacrylamide gel disc electrophoresis and SDS-polyacrylamide gel slab electrophoresis and in pI, but both showed a similar potency in biological activities. Ouchterlony double diffusion test revealed that the purified SLT-IIva and SLT-IIv (VT2vp) formed a spur against anti-SLT-IIva and anti-SLT-IIv (VT2vp) antisera.

Preventive effect of a new calcium antagonist, monatepil, on drug-induced ischaemic electrocardiographic changes in rats

1. The preventive effects of monatepil, a new calcium antagonist with alpha 1-adrenoceptor blocking activity, on ischaemic electrocardiographic changes in rat models of vasospastic angina were evaluated and compared with those of the existing calcium antagonists (diltiazem, verapamil, nicardipine and nifedipine). 2. In order to assess the contribution of the alpha 1-adrenoceptor blocking action of monatepil to its anti-vasospastic action, the anti-ST depression effect of prazosin, an alpha 1-adrenoceptor blocker, was also examined. 3. Monatepil given orally (3-30 mg/kg) inhibited vasopressin (0.2 IU/kg, i.v.)-induced ST depression which is considered to indicate ischaemic electrocardiographic changes in a vasospastic angina. This effect of monatepil was more potent and long-lasting than that of diltiazem, and was similar to that of verapamil and nicardipine. At a dose of 30 mg/kg, monatepil produced a significant inhibition, even at 7 h after administration. 4. Monatepil given intravenously (0.3 mg/kg) exerted a significant inhibitory effect on methacholine (16 micrograms/kg, intracoronary arterial administration; i.c.a.)-induced ST elevation which seems to be caused by coronary vasospasm. This effect was more potent or equipotent to those of the existing calcium antagonists. 5. These results indicate that monatepil produces the preventive effect on the drug-induced ischaemic electrocardiographic changes in rats and suggest that monatepil may have potential for the treatment of vasospastic angina.

Virulence patterns of Vibrio cholerae non-O1 strains isolated from hospitalised patients with acute diarrhoea in Calcutta, India

A collection of 28 strains of Vibrio cholerae non-O1 isolated during a 3-year period (1989-1991) from hospitalised patients with acute diarrhoea in Calcutta, India, were examined with regard to virulence-associated factors. Of the 28 isolates (each representing a case), 18 were isolated as the sole infecting agent; the remaining 10 were recovered as co-cultures from cases infected with V. cholerae O1. Of the strains isolated in this study, 82% could be serotyped, with serovars O5 (32.1%), O11 and O34 (14.3% each) predominant. Serovars O7, O14, O34, O39 and O97 were associated exclusively with sole infections. Two strains of V. cholerae non-O1 produced anti-cholera toxin IgG-absorbable cholera toxin (CT). Both CT-producing V. cholerae non-O1 strains hybridised with the DNA probe specific for the zonula occludens toxin (ZOT) but none of the remaining 26 strains hybridised with the ZOT probe. The majority of the strains were cytotoxic for CHO, HeLa and Vero cells, with end-point titres of 4-512. Fewer strains produced a cytotonic effect, with end-point titres of 2-16. Of the 28 strains of V. cholerae non-O1 examined, 75%, 75%, 25% and 14.3% produced haemolysin that was active against erythrocytes of rabbit, sheep (Eltor haemolysin), chicken and man, respectively. Strains that produced a haemolysin active against both rabbit and sheep erythrocytes were dominant (35.7%). Ten (35.7%) of the 28 strains examined showed cell-associated haemagglutinating activity on human blood. Of the 10 strains, nine were isolated as sole pathogen and only one strain was associated with mixed infection.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro and in vivo electrocardiographic evaluation of the novel calcium antagonist monatepil on cardiac conduction system

Effects of monatepil ([(+/-)-N-(6,11-dihydrodibenzo[b, e]thiepin-11-yl)-4-(p-fluorophenyl)-1-piperazinebutyramide]m aleate, AJ-2615, CAS 103377-41-9), a novel calcium antagonist, on the cardiac conduction system were compared by electrocardiography with those of the existing calcium antagonists (diltiazem, verapamil and nifedipine) in isolated rabbit heart preparations in vitro and in anesthetized and conscious dogs in vivo. Monatepil (10(-7) mol/l) prolonged the atrio-His bundle conduction time (AH interval) in the Langendorff perfused rabbit heart, like diltiazem, verapamil and nifedipine. This prolongation was decreased to 1/10 in the presence of 3.6% bovine serum albumin. In anesthetized dogs, monatepil (0.1-1.0 mg/kg i.v.), unlike diltiazem and verapamil, did not prolong AH interval. In conscious dogs, monatepil even at 100 mg/kg p.o. did not affect electrocardiograms. At the high dose of 300 mg/kg p.o., only a slight prolongation of the QT interval was found, but the QTc interval was not affected. Diltiazem at 10 mg/kg p.o. caused a prolongation of the PR interval and a disappearance of QRS waves. In conscious renal hypertensive dogs, repeated administration of monatepil (10 mg/kg/d p.o. for 29 days) had little effect on the conduction system of the heart examined by electrocardiograms, albeit a persistent fall in blood pressure continued throughout the administration period. The above results suggest that monatepil is a highly safe drug in the treatment of hypertension.

Anti-arrhythmic effects of a new calcium antagonist, monatepil, AJ-2615, in experimental arrhythmic models [corrected]

1. To characterize the anti-arrhythmic properties of a new calcium antagonist, monatepil [corrected], AJ-2615, the preventive effects of AJ-2615 were compared with those of the existing calcium antagonists, diltiazem and verapamil, in experimental models of arrhythmia. 2. AJ-2615 (0.1-3.0 mg/kg, i.v.) suppressed ventricular arrhythmias induced by adrenaline (10 micrograms/kg, i.v.) in rats. AJ-2615 (0.1 mg/kg per min for 2 min, i.v.) also suppressed atrial tachycardia induced by aconitine (0.01% aconitine solution) in rats. 3. In these activities, AJ-2615 was comparable to or more potent than diltiazem and verapamil which are widely used for the treatment of arrhythmia. 4. In pro-arrhythmic activity, AJ-2615 was less potent than diltiazem and verapamil. 5. These results suggest that AJ-2615 would be a safer anti-arrhythmic agent, with less proarrhythmic liability than diltiazem and verapamil.

Development of simulation models for protein folding in a thermal annealing process--I: A simulation of BPTI folding by the pearl necklace model

A model system is proposed to simulate the folding processes of proteins during thermal annealing. This system consists of four subsystems: (i) the pearl necklace model with isotropic inter-residue interactions; (ii) the extended pearl necklace model with anisotropic interaction potentials; (iii) molten globule phase dynamics; and (iv) final generation of the three-dimensional structure of a given protein. In this paper results obtained with the pearl necklace model are reported. This model consists of spherical elements and virtual bonds of 3.8 A in length and is intended to simulate dynamical processes at relatively high temperature where entropic terms play a dominant role. Inter-residue interactions are composed of spherical soft repulsive potentials and hydrophobic interactions inherent to respective residues. A simulation of folding processes of BPTI starting from the fully extended conformation indicated that intermediates, even at early stages of folding, are not randomly coiled but assume organized structures that resemble, to some extent, the native conformation.

Cloning and sequencing of two new Verotoxin 2 variant genes of Escherichia coli isolated from cases of human and bovine diarrhea

We cloned and sequenced two new Verotoxin 2 (VT2) variant genes: one from an Escherichia coli strain from a case of bovine diarrhea and the other from an E. coli strain from a patient with diarrhea. The nucleotide and amino acid sequences of these two genes were highly homologous with, but distinct from those of the VT2, VT2vha, VT2vhb, SLT-IIv (VT2vp1) and SLT-IIva (VT2vp2) genes. Their nucleotide sequences were much more closely homologous to that of VT2vh than to that of VT2vp. Search for these two new genes in other Verocytotoxin-producing E. coli strains resulted in the isolation of 2 strains carrying one of the new VT2 variant genes, one strain from Tokyo and the other from Canada.

Antihypertensive effects of AJ-2615, a new calcium antagonist with alpha 1-adrenergic blocking activity in experimental hypertensive animals

The antihypertensive effect of AJ-2615 [(+/-)-N-(6,11-dihydrodibenzo[b,e]thiepin-11-yl)-4-(4-fluoro phenyl)-1- piperazinebutanamide maleate], a novel calcium (Ca) antagonist having alpha 1-adrenergic blocking activity as well, was compared with that of the existing Ca antagonists (diltiazem, nifedipine, and nicardipine) in various hypertensive models of dogs and rats. When given orally to renal hypertensive dogs (RHDs) and spontaneously hypertensive rats (SHRs), AJ-2615 (RHDs, ED25 mm Hg = 6.0 mg/kg; SHRs, ED25 mm Hg = 24.9 mg/kg) was approximately as effective as diltiazem (RHDs, ED25 mm Hg = 6.3 mg/kg; SHRs, ED25 mm Hg = 54.7 mg/kg) in lowering the blood pressure. This antihypertensive effect was slower in onset and longer in duration (RHDs, > or = 9 h; SHRs, > or = 20 h) compared with any of the other reference drugs. AJ-2615 (10 mg/kg p.o.) given to RHDs once daily for 29 days significantly reduced the blood pressure measured 24 h after each dose and caused a stable antihypertensive effect without major diurnal variations. When given in single oral doses to RHDs and SHRs, AJ-2615 had no large effect on the heart rate while the reference drugs induced a large increase or decrease in heart rate in response to a blood pressure fall. These results suggested that AJ-2615 has potential as a long-acting (once daily dosage regimen) antihypertensive drug without causing a steep blood pressure fall and tachycardia.

Identification and characterization of heat-stable enterotoxin II-producing Escherichia coli from patients with diarrhea

Stock strains of Escherichia coli isolated from patients with traveller's diarrhea were examined for production of heat-stable enterotoxin II (STII). Of 400 strains examined, 3 were found to produce STII. The nucleotide sequence of the STII gene of these human strains was shown to be identical to that of porcine strains. Cultured cells of these strains induced fluid accumulation in ligated mouse intestinal loops and the activity was neutralized by anti-STII antiserum. These results suggest that STII-producing enterotoxigenic E. coli can cause human diarrhea.

Inhibitory effect of the new calcium antagonist AJ-2615 on progression of atherosclerosis in cholesterol-fed rabbits

The effects of a new calcium antagonist, AJ-2615, on progression of atherosclerosis were investigated in rabbits fed a diet high in cholesterol and compared with those of prazosin, diltiazem, and their combination. In the AJ-2615 (30 mg/kg p.o. once daily) group, high cholesterol diet-induced increases in plasma concentrations of total cholesterol, free cholesterol, and phospholipid were significantly decreased. In addition, increases in aortic lipids and calcium content, as well as those in the atherosclerotic lesion area were clearly reduced by AJ-2615. On the other hand, prazosin (3 mg/kg p.o. twice daily) and diltiazem (50 mg/kg p.o. twice daily) groups displayed no such inhibitory effects. However, the group receiving the combination of prazosin and diltiazem at their respective dose levels exhibited a significant reduction in the increase in calcium content of the aorta and a slight decrease in the atherosclerotic lesion area, although there was no decrease in plasma or aortic lipid content. These results suggest that in addition to its calcium antagonistic and alpha 1-adrenoceptor blocking actions, some other yet-unidentified properties of AJ-2615 might contribute to the antiatherosclerotic effect of this agent.

Inhibitory effect of zonisamide on human carbonic anhydrase in vitro

We examined the relative potencies of zonisamide (CAS 68291-97-4) to acetazolamide in inhibiting carbonic anhydrases in human erythrocytes and purified human carbonic anhydrase I and II in vitro and found them to be about 1/150, 1/8 and 1/188, respectively. The IC50 values of zonisamide and acetazolamide for the inhibition of erythrocyte enzymes were close to those of purified carbonic anhydrase II. This result indicates that zonisamide actually differs from acetazolamide in their actions on the physiological events which are coupled with CO2 hydration in vivo.

[Association of pre-core defective HBV mutant with anti-HBe positive chronic hepatitis]

Precore defective HBV mutant has been suggested to be responsible for the pathogenesis of fulminant hepatitis. This variant is unable to produce HBeAg because of the presence of a novel translational stop codon at the end of the precore region of the genome. We examined the precore region of the HBV nucleotide sequence in 12 Japanese anti-HBe positive chronic hepatitis patients in order to ascertain whether the genome has stop-codon mutation in the precore region. Precore defective HBV mutant was found in most of the examined cases. A few cases had a mixture of strains, wild type and precore defective HBV mutant. The variety of precore genome concerned with the pathogenesis of chronic hepatitis still needs to be clarified.

Distribution of the zot (zonula occludens toxin) gene among strains of Vibrio cholerae 01 and non-01

The distribution of the zot gene that encodes the zonula occludens toxin, a newly described toxin of Vibrio cholerae, among clinical, environmental and food isolates of V. cholerae 01 and non-01 was investigated. Both the zot gene and the ctx gene that encode cholera toxin were found in 247 of 257 clinical strains and 62 of 415 environmental or food isolates of V. cholerae 01. The zot gene, but not the ctx gene was found in 37 strains (one clinical strain and 36 environmental or food isolates). In addition, two of 31 clinical strains and six of 98 environmental or food isolates of V. cholerae' non-01 possessed both the zot gene and the ctx gene. These results demonstrated the predominantly concurrent occurrence of the zot gene and ctx genes among strains of V. cholerae 01 which suggests a possible synergistic role of ZOT in the causation of acute dehydrating diarrhea produced by V. cholerae 01.

Pharmacological profile of AD-5423, a novel antipsychotic with both potent dopamine-D2 and serotonin-S2 antagonist properties

The pharmacological properties of AD-5423 [2-(4-ethyl-1-piper-azinyl)-4- (4-fluorophenyl)-5,6,7,8,9,10-hexahydrocycloocta[b]pyridine] were studied in biochemical and behavioral tests. In vitro, AD-5423 bound preferentially to dopamine (DA)-D2 (Ki, 14.8 nM; cf. haloperidol, 8.79 nM; and clozapine, 149 nM) and serotonin (5-HT)-S2 (Ki, 3.98 nM; cf. haloperidol, 26.8 nM; and clozapine, 8.66 nM) receptors. It displayed low affinity for adrenaline (Ad)-alpha-1 (Ki, 56.3 nM) receptors and was virtually devoid of binding to DA-D1 (Ki, 2870 nM), 5-HT-S3, Ad-alpha-2, Ad-beta, muscarine, tau-aminobutyric acid and benzodiazepine receptors. In addition, AD-5423 was only a weak inhibitor of DA, 5-HT and noradrenaline uptake systems. When administered p.o., AD-5423 (0.3-10 mg/kg) increased brain contents of the DA metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid in mice and rats and the 5-HT metabolite 5-hydroxyindoleacetic acid in mice. Behaviorally, AD-5423 (0.2-2 mg/kg p.o.) decreased exploratory activity in mice, suppressed conditioned avoidance responding and methamphetamine-induced hyperactivity in mice and rats, antagonized apomorphine-induced gnawing in rats and vomiting in dogs and reduced hostile responses in monkeys. In these effects, AD-5423 was more or less equi-potent to haloperidol. However, AD-5423 (10 mg/kg p.o.), unlike haloperidol, did not antagonize SKF38393-induced vacuous oral movements in rats. Head twitches induced by 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane in mice and by para-chloroamphetamine in rats were antagonized by AD-5423 at much lower doses (0.5-2 mg/kg p.o.) than those of haloperidol and clozapine.(ABSTRACT TRUNCATED AT 250 WORDS)

AS-4370, a new gastrokinetic agent, enhances upper gastrointestinal motor activity in conscious dogs

The effects of AS-4370 [4-amino-5-chloro-2-ethoxy-N-(4-(4-fluorobenzyl)-2 morpholinyl)methyl)benzamide citrate] on gastrointestinal (GI) motor activity were compared with those of cisapride and metoclopramide in conscious dogs with force transducers implanted chronically. In postprandial state, AS-4370 given 0.2 to 1 mg/kg i.v. or 1 mg/kg intraduodenally (i.d.) stimulated the antral and duodenal motor activity without affecting the colonic motor activity. Cisapride at 0.2 to 1 mg/kg i.v. or 1 mg/kg i.d. stimulated the motor activity in all sites of the GI tract from the stomach to the colon simultaneously. Metoclopramide, like AS-4370, stimulated the antral and duodenal motor activity, but its effect was less potent than that of AS-4370. AS-4370 did not stimulate the GI motor activity under treatment with atropine but stimulated it under vagotomy. Furthermore, AS-4370 did not potentiate the methacholine-induced antral contraction, whereas neostigmine at 10 micrograms/kg i.v. significantly enhanced it. AS-4370 at 1 mg/kg i.v. did not antagonize the inhibition of antral motor activity induced by i.v. infusion of dopamine (1 mg/kg/hr), whereas cisapride (0.5 mg/kg i.v.) and metoclopramide (1 mg/kg i.v.) antagonized it. In addition, the enhancement of GI motor activity induced by AS-4370 was not prevented by propranolol, prazosin, yohimbine, methysergide, ketanserin, ICS 205-930 or naloxone. 5- Hydroxytryptamine (5-HT) receptor desensitization induced by 5-HT (300 micrograms/kg/hr) in the antrum reduced the enhancement induced by AS-4370.(ABSTRACT TRUNCATED AT 250 WORDS)

Novel benzamides as selective and potent gastrokinetic agents. 2. Synthesis and structure-activity relationships of 4-amino-5-chloro-2-ethoxy-N-[[4-(4-fluorobenzyl)-2- morpholinyl]methyl] benzamide citrate (AS-4370) and related compounds

The title compounds (19-55) with a 4-substituted 2-(aminomethyl)morpholine group were prepared and evaluated for the gastrokinetic activity by determining their effect on gastric emptying of phenol red semisolid meal in rats. Introduction of chloro, fluoro, and trifluoromethyl groups to the benzyl group of the parent compounds 1a and 1b enhanced the activity. Among compounds tested, 4-amino-5-chloro-2-ethoxy-N-[[4-(4-fluorobenzyl)-2-morpholinyl] methyl] benzamide (23b) showed the most potent gastric emptying activity (effects on phenol red semisolid meal in rats and mice, and on resin pellets solid meal in rats). The gastrokinetic activity of 23b citrate (AS-4370) compared very favorably with that of cisapride and was higher than that of metoclopramide. In contrast to metoclopramide and cisapride, AS-4370 was free from dopamine D2 receptor antagonistic activity in both in vitro ([3H]spiperone binding) and in vivo (apomorphine-induced emesis in dogs) tests.

Memory deficits following internal capsule lesions in rats and their improvement by L-6-ketopiperidine-2-carbonyl-L-leucyl-L-proline amide (RGH-2202), a thyrotropin-releasing hormone analogue

A memory deficit model has been developed following bilateral internal capsule lesions in rats. During 12-49 days after internal capsule lesions, the rats showed a marked impairment of active avoidance acquisition in a step-through apparatus, while they exhibited no observable change in native behaviors, except a slight increase in exploratory activity. A passive avoidance task in the same apparatus was also impaired in internal capsule lesioned rats when examined after one-trial training, though the task was gradually acquired by repeated trainings. Moreover, the retention of both the active and passive avoidance responses in well-trained rats deteriorated after internal capsule lesions. On the other hand, internal capsule-lesioned rats did not perform any worse than sham-operated rats in a T-maze spontaneous alternation behavior and in a habituation response to a novel environment. In the frontal cortex and striatum of internal capsule-lesioned rats, there was a significant decrease of dopamine, serotonin and their metabolites, but no change of acetylcholine levels. The acquisition deficit of active avoidance in internal capsule-lesioned rats was improved by thyrotropin-releasing hormone (TRH, 10 mg/kg, i.p.) and L-6-ketopiperidine-2-carbonyl-L-leucyl-L-proline amide (RGH-2202, 10 mg/kg, i.p., 0.2 and 1 mg/kg i.v.), but not by physostigmine sulfate (0.2 mg/kg, i.p.). These results indicate that bilateral internal capsule lesions in rats induce long-term memory deficits which are paralleled with a decrease of the contents of monoamines and their metabolites and improved by TRH and RGH-2202.

Novel benzamides as selective and potent gastric prokinetic agents. 1. Synthesis and structure-activity relationships of N-[(2-morpholinyl)alkyl]benzamides

With the purpose of obtaining more potent and selective gastric prokinetic than metoclopramide (1), a new series of N-[(2-morpholinyl)alkyl]benzamides (17-52) were synthesized and their gastric prokinetic activity was evaluated by determining effects on the gastric emptying of phenol red semisolid meal and of resin pellets solid meal in rats and mice. The morpholinyl moiety was newly designed after consideration of the side-chain structure of cisapride (2) and produced the desired activity when coupled with the 4-amino-5-chloro-2-methoxybenzoyl group of both metoclopramide and cisapride. Modification of the substituents of the benzoyl group markedly influenced the activity. In particular, 4-amino-N-[(4-benzyl-2-morpholinyl)methyl]-5-chloro-2-methoxybenzamide (17) and the 4-(dimethylamino) and 2-ethoxy analogues (25 and 29) of 17 showed potent and selective gastric prokinetic activity along with a weak dopamine D2 receptor antagonistic activity.

Interaction of zonisamide with benzodiazepine and GABA receptors in rat brain

The effects of zonisamide on [3H]flunitrazepam binding and [3H]muscimol binding were studied in Sprague-Dawley rat brain. Specific [3H]flunitrazepam bound was decreased to 64.6 +/- 5.6% (mean +/- SD, n = 5, p < 0.002) and 91.9 +/- 4.0% (p < 0.005) by the addition of 10(-3) M and 10(-4) M zonisamide, respectively. Scatchard plot analysis of [3H]flunitrazepam binding with 10(-3) M of zonisamide revealed an increased Kd value with no change in Bmax. No inhibitory effect of zonisamide was seen on the enhancement of specific [3H]flunitrazepam binding by GABA. As for the effects on GABA receptors, specific [3H]muscimol bound was decreased to 27.7 +/- 10.4% (mean +/- SD, n = 4, p < 0.005) and 68.3 +/- 3.7% (mean +/- SD, n = 4, p < 0.005) by the addition of 10(-3) M and 10(-4) M zonisamide, respectively. Since therapeutic serum level of zonisamide are around 10(-4) M, these results suggest that zonisamide neuropharmacologically interacts with the GABA/benzodiazepine receptor ionophore complex in a manner similar to phenytoin.

[3H]zonisamide binding in rat brain

We previously reported that zonisamide inhibits both [3H]flunitrazepam and [3H]muscimol binding in rat brain. In the present study, [3H]zonisamide was found to bind in a saturable fashion to the crude synaptosomal fraction of whole rat brain. Linear regression analysis of the binding data in the Scatchard plot indicated a Kd of 90 nM, and a maximal binding capacity of 1.40 x 10(3) fmol/mg protein. Displacement studies revealed an inhibitory effect of clonazepam and an enhancement effect of GABA on specific [3H]zonisamide binding. These results suggest that specific [3H]zonisamide binding sites may have a tight correlationship with benzodiazepine receptors in rat brain.

AS-4370, a novel gastrokinetic agent free of dopamine D2 receptor antagonist properties

The gastrokinetic effects of AS-4370, 4-amino-5-chloro-2-ethoxy-N-([4-(4-fluorobenzyl)-2-morpholinyl] methyl) benzamide citrate, were compared with those of metoclopramide in experimental animals. In rats, AS-4370 increased the gastric emptying of a semi-solid meal and of resin pellets at dose ranges of 0.03-30 mg/kg and 1-10 mg/kg p.o., respectively. The minimal effective doses were 3-10 times lower than those of metoclopramide. Gastric emptying, delayed by gastroduodenal surgical intervention, was improved with AS-4370 (0.3-3 mg/kg p.o.). In conscious dogs with strain gauges implanted, AS-4370 (0.5 and 1.0 mg/kg i.v.) enhanced antral and duodenal motility without affecting ileal and colonic motility, indicating a selective enhancing effect on upper gastrointestinal motility. AS-4370 (10(-7) - 3 x 10(-5) M) increased electrically evoked, cholinergically mediated contractions in isolated guinea-pig ileum. AS-4370 (3 mg/kg i.v.) was without effect on gastric acid secretion in anesthetized rats. Unlike metoclopramide, AS-4370 neither depressed the active avoidance response in mice nor the food-reinforced lever pressing response in rats, even at 100 mg/kg p.o. Moreover, AS-4370 (10(-4) M) showed no affinity for D2, alpha 1, alpha 2, 5-HT1 and 5-HT2 binding sites in rat brain synaptic membranes. These results suggest that AS-4370 is a new and potent gastrokinetic agent that lacks dopamine D2 receptor antagonist properties.

L-6-ketopiperidine-2-carbonyl-L-leucyl-L-proline amide as a novel thyrotropin releasing hormone analogue with improving effects on impaired central nervous systems functions

Psychopharmacological activities of L-6-ketopiperidine-2-carbonyl-L-leucyl-L-proline amide (RGH-2202) were compared with those of the parent peptide, thyrotropin releasing hormone (TRH, L-pyroglutamyl-L-histidyl-L-prolinamide, Pyr-His-Pro amide) in rodents. RGH-2202 caused qualitatively similar effects to TRH in a variety of tests for the activity on the central nervous system. The compound as well as TRH increased the spontaneous motor activity, enhanced the conditioned avoidance response, and antagonized the avoidance suppression by haloperidol and the sleep-inducing effect of pentorbarbital in mice. It was also efficacious against the deficits of consciousness in mice with concussive head injury and the EEG disturbance in rats with basilar artery occlusion. Besides, it antagonized the cycloheximide-or anoxia-induced amnesia and enhanced the habituation of exploratory activity in mice. Biochemically, it enhanced, like TRH, the turnover of norepinephrine and dopamine in the cerebral cortex, nucleus accumbens and striatum of mice and rats, and increased cyclic GMP levels in the cerebellum of rats. In spite of the global similarity between the pharmacological profiles of RGH-2202 and TRH, there were some intriguing differences between them. RGH-2202 was 2-5 times more effective than TRH in improving the deficits of active avoidance performance and retention in mice, while it was weaker than TRH in modifying the haloperidol-induced catalepsy in mice and enhancing the spinal reflexes in rats. Besides, its thyrotropin releasing activity was about 30 times less potent than that of TRH.(ABSTRACT TRUNCATED AT 250 WORDS)

Pathological state of the coagulatory and fibrinolytic system in preeclampsia and the possibility of its treatment with AT III concentrate

Forty patients with preeclampsia were collected, and 27 of these cases were treated with AT III concentrate (1,000-2,000 units/day) for 7 days. According to an evaluation of objective clinical efficacy by the degree of improvement of GI scores in patients with preeclampsia, the number of effective cases was significantly greater among the treated groups than among the untreated groups (p less than 0.05). The rate of efficacy of the treated groups was 40%, compared with 0% in the untreated groups. In severe preeclampsia, a decrease in AT III activity was noted in 56.7%, a decrease in platelet count in 62.1%, and an increase in plasma FDP in 46.2%. A significant correlation was found between the GI score and the AT III activity. The anticoagulation therapy using AT III may normalize the chronic coagulation accelerated state in preeclampsia, and a good influence on the fetus may be expected.