Inhibitory effects of opioids on compound action potentials in frog sciatic nerves and their chemical structures

An opioid tramadol more effectively inhibits compound action potentials (CAPs) than its metabolite mono-O-demethyl-tramadol (M1). To address further this issue, we examined the effects of opioids (morphine, codeine, ethylmorphine and dihydrocodeine) and cocaine on CAPs by applying the air-gap method to the frog sciatic nerve. All of the opioids at concentrations less than 10 mM reduced the peak amplitude of the CAP in a reversible and dose-dependent manner. The sequence of the CAP peak amplitude reductions was ethylmorphine>codeine>dihydrocodeine> or = morphine; the effective concentration for half-maximal inhibition (IC(50)) of ethylmorphine was 4.6 mM. All of the CAP inhibitions by opioids were resistant to a non-specific opioid-receptor antagonist naloxone. The CAP peak amplitude reductions produced by morphine, codeine and ethylmorphine were related to their chemical structures in such that this extent enhanced with an increase in the number of -CH(2) in a benzene ring, as seen in the inhibitory actions of tramadol and M1. Cocaine reduced CAP peak amplitudes with an IC(50) value of 0.80 mM. It is concluded that opioids reduce CAP peak amplitudes in a manner being independent of opioid-receptor activation and with an efficacy being much less than that of cocaine. It is suggested that the substituted groups of -OH bound to the benzene ring of morphine, codeine and ethylmorphine as well as of tramadol and M1, the structures of which are quite different from those of the opioids, may play an important role in producing nerve conduction block.     

Lafutidine,a novel histamine H2-receptor antagonist,vs lansoprazole in combination with amoxicillin and clarithromycin for eradication of Helicobacter pylori

Background. In contrast to the growing amount of data concerning proton pump inhibitor‐based triple therapy for Helicobacter pylori infection, it is still controversial whether proton pump inhibitor can be replaced by H₂ receptor antagonist without compromising efficacy. Lafutidine is a novel potent H₂ receptor antagonist with gastroprotective activities such as enhancement of gastric mucosal blood flow. Methods. 122 outpatients with positive cultures and subsequent successful cultivation of H. pylori for antimicrobial susceptibility tests were randomized to receive a 7‐day course of either lafutidine (20 mg twice daily) or lansoprazole (30 mg twice daily), plus clarithromycin (200 mg twice daily) and amoxicillin (750 mg twice daily). Eradication was considered successful if the rapid urease test, culture, histology and [ 13 ]C‐urea breath test were all negative at least 4 weeks after cessation of therapy. Cytochrome p450 2C19 genotype status using polymerase chain reaction‐restriction fragment length polymorphism was also studied. Results. On intention‐to‐treat basis, H. pylori cure was achieved in 52 of 61 (85.2%) patients and 49 of 61 (80.3%) patients for the lafutidine‐ and lansoprazole‐based therapies, respectively. The predicted 95% confidential intervals for the 4.9% of the difference were ?1.8–11.6%. Using per protocol analysis, the eradication rates were 88.2% (52/59) and 84.5% (49/58), respectively. The predicted 95% confidential intervals for the 3.7% of the difference were ?2.6–10.0%. Adverse events were observed in five and six patients, from the lafutidine and lansoprazole groups, respectively, but they were generally mild. Genetic predisposition of cytochrome p450 2C19 had no significant influence on treatment outcome in both regimens. Conclusions. The lafutidine‐clarithromycin‐amoxicillin therapy yielded satisfactory results for eradicating H. pylori, which was comparable with those of the lansoprazole‐based regimen with the same drug combination.     

Cloning of a novel homeobox (NK-7.1) containing gene,DmHboxNK-7.1, from Drosophila melanogaster

We have cloned a novel Drosophila melanogaster homeobox (Hbox) containing gene, NK-7.1 (Dm.HboxNK-7.1), which is located at 88B3 on the chromosome map, and is 1.5 kb downstream of the spn-B gene. The newly identified gene is expressed at high levels in the embryo, is switched off during larval and pupal stages, and is expressed again in the adult. The Hbox is highly similar to NK-1/S59 (Drosophila) and NK-3/bap (Drosophila). The amino acid (aa) identity ratios (%) were 58 between NK-7.1 and NK-1/S59, and between NK-7.1 and NK-3/bap. The other characteristic structures are the presence of homopolymeric aa stretches consisting of Q, N, and E.     

Frequent reassortment among influenza C viruses

In a 9-year survey from December 1990 to December 1999 in Sendai City, Japan, we succeeded in isolating a total of 45 strains of influenza C virus. These 45 strains were isolated in clusters within 4 months in a year, especially from winter to early summer. Previous studies of the hemagglutinin-esterase genes of various influenza C virus isolates revealed the existence of five distinct virus lineages (Aichi/1/81-, Yamagata/26/81-, Mississippi/80-, Sao Paulo/82-, and Kanagawa/1/76-related lineage) in Japan between 1970 and the early 1990s (Y. Matsuzaki, K. Mizuta, H. Kimura, K. Sugawara, E. Tsuchiya, H. Suzuki, S. Hongo, and K. Nakamura, J. Gen. Virol. 81:1447-1452, 2000). Antigenic and genetic analyses of the 45 strains showed that they could be divided into these five virus lineages and a few antigenic groups were cocirculating in Sendai City. In 1990 and 1991 the dominant antigenic group was the Aichi/1/81 virus group, and in 1992 it was Yamagata/26/81 virus group. The Mississippi/80 virus group was isolated from 1993 to 1996, and the Yamagata/26/81 virus group reemerged in 1996 and continued to circulate until 1999. This finding led us to a speculation that the replacement of the dominant antigenic groups had occurred by immune selection within the human population in the restricted area. Phylogenetic analysis of seven RNA segments showed that 44 viruses among the 45 strains isolated in our surveillance work were reassortant viruses that have various genome compositions distinguishable from those of the reference strains of the each lineage. This observation suggests that the reassortment between two different influenza C virus strains occurs frequently in nature and the genome composition of influenza C viruses may influence their ability to spread in humans.     

Gonadal state of wild amphioxus populations and spawning success in captive conditions during the breeding period in Japan

Adult individuals of amphioxus (Branchiostoma belcheri) were collected by dredging from a research vessel at selected stations in two areas off the coast of Japan in July 2000: Deyama and Takamatsu so named by local fishermen in the Enshu Nada Sea. The number of males collected exceeded that of females at all the stations in Takamatsu and at four of five stations in Deyama. The over all sex ratio (males : females) of the collected animals was 1.2 : 1. The animals showed various maturational stages of the gonad, and approximately 70% had mature gonads. However, post-spawning animals were identified only at two stations in Takamatsu. Mature animals were placed in laboratory tanks. These animals remained in good conditions for about two months, and many animals spontaneously spawned in the tanks. This is the first report of spontaneous spawning of B. belcheri in Japan.     

Overexpression of suppressor of cytokine signaling-3 in T cells exacerbates acetaminophen-induced hepatotoxicity

Cytokines have been implicated in the progression of acetaminophen (APAP)-induced acute liver injury. Suppressors of cytokine signaling (SOCS) proteins are negative regulators of cytokine signaling by inhibiting the JAK-STAT pathway, but their role in APAP hepatotoxicity is unknown. In this present study, we attempted to explore the role of SOCS3 in T cells in APAP-induced liver injury. Mice with a cell-specific overexpression of SOCS3 in T cells (SOCS3Tg, in which Tg is transgenic) exhibited exaggerated hepatic injury after APAP challenge, as evidenced by increased serum alanine aminotransferase levels, augmented hepatic necrosis, and decreased survival relative to the wild-type mice. Adaptive transfer of SOCS3Tg-CD4(+) T cells into T and B cell-deficient RAG-2(-/-) mice resulted in an exacerbated liver injury relative to the control. In SOCS3Tg mice, hepatocyte apoptosis was enhanced with decreased expression of antiapoptotic protein bcl-2, whereas hepatocyte proliferation was reduced with altered cell cycle-regulatory proteins. Levels of IFN-gamma and TNF-alpha in the circulation were augmented in SOCS3Tg mice relative to the control. Studies using neutralizing Abs indicated that elevated IFN-gamma and TNF-alpha were responsible for the exacerbated hepatotoxicity in SOCS3Tg mice. Activation of STAT1 that is harmful in liver injury was augmented in SOCS3Tg hepatocytes. Alternatively, hepatoprotective STAT3 activation was decreased in SOCS3Tg hepatocytes, an event that was associated with augmented SOCS3 expression in the hepatocytes. Altogether, these results suggest that forced expression of SOCS3 in T cells is deleterious in APAP hepatotoxicity by increasing STAT1 activation while decreasing STAT3 activation in hepatocytes, possibly through elevated IFN-gamma and TNF-alpha.     

A Bax/Bak-independent mechanism of cytochrome c release

Bax and Bak are multidomain pro-apoptotic members of the Bcl-2 family of proteins that regulate mitochondria-mediated apoptosis by direct modulation of mitochondrial membrane permeability. Since double-knock-out mouse embryonic fibroblasts with deficiency of Bax and Bak are resistant to multiple apoptotic stimuli, Bax and Bak are considered to be an essential gateway for various apoptotic signals. Here we showed that the combination of calcium ionophore A23187 and arachidonic acid induced cytochrome c release and caspase-dependent death of double-knock-out mouse embryonic fibroblasts, indicating that other mechanisms of cytochrome c release exist. Furthermore, A23187/arachidonic acid (ArA)-induced caspase-dependent death was significantly suppressed by the treatment of several serine protease inhibitors including 4-(2-aminoethyl)benzenesulfonylfluoride and l-1-chloro-3-(4-tosylamido)-4-phenyl-2-butanone but not the overexpression of anti-apoptotic Bcl-2 family of proteins or the inhibition of mitochondrial membrane permeability transition. These results indicate that there are at least two mechanisms of cytochrome c release leading to caspase activation, a Bax/Bak-dependent mechanism and a Bax/Bak-independent, but serine protease(s)-dependent, mechanism.