Financial incentives for infection prevention and antimicrobial stewardship to reduce antibiotic use: Japan's nationwide observational study

BACKGROUND

The Japanese government introduced financial incentives to reduce nationwide antibiotic use in hospital settings.

AIM

This study aimed to determine whether the nationwide financial incentives for creating infection prevention and control (IPC) teams introduced in 2012 and antimicrobial stewardship (ASP) teams introduced in 2018 were associated with changes in antibiotic use and health resource utilization at a national level.

METHODS

We conducted time-series analyses and a difference-in-differences study consisting of 3,057,517 inpatients with infectious diseases from 472 medical facilities during fiscal years 2011-2018 using a nationally representative inpatient database in Japan. The primary outcome was the days of therapy (DOT) of antibiotic use per 100 patient-days (PDs). The secondary outcomes consisted of types of antibiotic used, health resource utilization, and mortality.

RESULTS

A total of 5,201,304 financial incentives were observed during 2012-2018, which resulted in a total of 12.1 billion JPY (≈110 million USD). Time-series analyses found decreasing trends in total antibiotic use (79.3-72.5 DOTs/100 PDs (8.6% reduction)) and carbapenem use (9.0-7.0 DOTs/100 PDs (7.8% reduction)) from 2011 to 2018 without adversely affecting other healthcare outcomes (e.g., mortality). In the difference-in-differences analyses, we did not observe meaningful changes in total antibiotic use between the incentivized and unincentivized hospitals for ASP teams, except for the northern part of Japan. No dose-response relationships were observed between the amount of financial incentives and reductions in antibiotic use during 2011-2019.

CONCLUSIONS

Further research and efforts are needed to accelerate antimicrobial stewardship in hospital settings in Japan.

Melanogenic effect of dersimelagon (MT-7117), a novel oral melanocortin 1 receptor agonist

Background

The activation of melanocortin 1 receptor (MC1R) on melanocytes stimulates the production of eumelanin. A tridecapeptide α melanocyte‐stimulating hormone (αMSH) is known to induce skin pigmentation.

Objectives

We characterised the properties of a novel oral MC1R agonist dersimelagon (MT‐7117) with respect to its specific binding to MC1R, downstream signalling and eumelanin production in experimental models.

Methods

The competitive binding and production of intracellular cyclic adenosine 3′, 5′‐monophosphate in cells expressing recombinant melanocortin receptors were examined. A mouse melanoma cell line B16F1 was used for the evaluation of in vitro melanin production. The in vitro activity of MT‐7117 was determined with αMSH and [Nle⁴, D‐Phe⁷]‐αMSH (NDP‐αMSH) as reference comparators. The change of coat colour and skin pigmentation were evaluated after repeat administration of MT‐7117 by oral gavage to C57BL/6J‐A^y/+ mice and cynomolgus monkeys, respectively.

Results

MT‐7117 showed the highest affinity for human MC1R compared to the other melanocortin receptors evaluated and agonistic activity for human, cynomolgus monkey and mouse MC1R, with EC₅₀ values in the nanomolar range. In B16F1 cells, MT‐7117 increased melanin production in a concentration‐dependent manner. In vivo, MT‐7117 (≥0.3 mg/kg/day p.o.) significantly induced coat colour darkening in mice. MT‐7117 (≥1 mg/kg/day p.o.) induced significant skin pigmentation in monkeys and complete reversibility was observed after cessation of its administration.

Conclusions

MT‐7117 is a novel oral MC1R agonist that induces melanogenesis in vitro and in vivo, suggesting its potential application for the prevention of phototoxic reactions in patients with photodermatoses, such as erythropoietic protoporphyria and X‐linked protoporphyria.

Functional role of the N-terminal domain of ΔFosB in response to stress and drugs of abuse

Previous work has implicated the transcription factor, ΔFosB, acting in the nucleus accumbens, in mediating the pro-rewarding effects of drugs of abuse such as cocaine as well as in mediating resilience to chronic social stress. However, the transgenic and viral gene transfer models used to establish these ΔFosB phenotypes express, in addition to ΔFosB, an alternative translation product of ΔFosB mRNA, termed Δ2ΔFosB, which lacks the N-terminal 78 aa present in ΔFosB. To study the possible contribution of Δ2ΔFosB to these drug and stress phenotypes, we prepared a viral vector that overexpresses a point mutant form of ΔFosB mRNA which cannot undergo alternative translation as well as a vector that overexpresses Δ2ΔFosB alone. Our results show that the mutant form of ΔFosB, when overexpressed in the nucleus accumbens, reproduces the enhancement of reward and of resilience seen with our earlier models, with no effects seen for Δ2ΔFosB. Overexpression of full length FosB, the other major product of the FosB gene, also has no effect. These findings confirm the unique role of ΔFosB in the nucleus accumbens in controlling responses to drugs of abuse and stress.

The rice endosperm ADP-glucose pyrophosphorylase large subunit is essential for optimal catalysis and allosteric regulation of the heterotetrameric enzyme

Although an alternative pathway has been suggested, the prevailing view is that starch synthesis in cereal endosperm is controlled by the activity of the cytosolic isoform of ADPglucose pyrophosphorylase (AGPase). In rice, the cytosolic AGPase isoform is encoded by the OsAGPS2b and OsAGPL2 genes, which code for the small (S2b) and large (L2) subunits of the heterotetrameric enzyme, respectively. In this study, we isolated several allelic missense and nonsense OsAGPL2 mutants by N-methyl-N-nitrosourea (MNU) treatment of fertilized egg cells and by TILLING (Targeting Induced Local Lesions in Genomes). Interestingly, seeds from three of the missense mutants (two containing T139I and A171V) were severely shriveled and had seed weight and starch content comparable with the shriveled seeds from OsAGPL2 null mutants. Results from kinetic analysis of the purified recombinant enzymes revealed that the catalytic and allosteric regulatory properties of these mutant enzymes were significantly impaired. The missense heterotetramer enzymes and the S2b homotetramer had lower specific (catalytic) activities and affinities for the activator 3-phosphoglycerate (3-PGA). The missense heterotetramer enzymes showed more sensitivity to inhibition by the inhibitor inorganic phosphate (Pi) than the wild-type AGPase, while the S2b homotetramer was profoundly tolerant to Pi inhibition. Thus, our results provide definitive evidence that starch biosynthesis during rice endosperm development is controlled predominantly by the catalytic activity of the cytoplasmic AGPase and its allosteric regulation by the effectors. Moreover, our results show that the L2 subunit is essential for both catalysis and allosteric regulatory properties of the heterotetramer enzyme.

Genome-wide association study identifies a potent locus associated with human opioid sensitivity

Opioids, such as morphine and fentanyl, are widely used as effective analgesics for the treatment of acute and chronic pain. In addition, the opioid system has a key role in the rewarding effects of morphine, ethanol, cocaine and various other drugs. Although opioid sensitivity is well known to vary widely among individual subjects, several candidate genetic polymorphisms reported so far are not sufficient for fully understanding the wide range of interindividual differences in human opioid sensitivity. By conducting a multistage genome-wide association study (GWAS) in healthy subjects, we found that genetic polymorphisms within a linkage disequilibrium block that spans 2q33.3-2q34 were strongly associated with the requirements for postoperative opioid analgesics after painful cosmetic surgery. The C allele of the best candidate single-nucleotide polymorphism (SNP), rs2952768, was associated with more analgesic requirements, and consistent results were obtained in patients who underwent abdominal surgery. In addition, carriers of the C allele in this SNP exhibited less vulnerability to severe drug dependence in patients with methamphetamine dependence, alcohol dependence, and eating disorders and a lower 'Reward Dependence' score on a personality questionnaire in healthy subjects. Furthermore, the C/C genotype of this SNP was significantly associated with the elevated expression of a neighboring gene, CREB1. These results show that SNPs in this locus are the most potent genetic factors associated with human opioid sensitivity known to date, affecting both the efficacy of opioid analgesics and liability to severe substance dependence. Our findings provide valuable information for the personalized treatment of pain and drug dependence.

Geissoschizine methyl ether, an alkaloid in Uncaria hook, is a potent serotonin ₁A receptor agonist and candidate for amelioration of aggressiveness and sociality by yokukansan

Yokukansan (YKS), a traditional Japanese medicine, is composed of seven kinds of dried herbs. It is widely prescribed in clinical situation for treating psychiatric disorders such as aggressiveness in patients with dementia. We previously demonstrated that YKS and Uncaria hook (UH), which is a constituent herb of YKS, had a partial agonistic effect to 5-HT(1A) receptors in vitro. However, it has still been unclear whether this in vitro effect is reflected in in vivo, and what the active ingredients are. The purpose of the present study is to find the active ingredient in YKS and to demonstrate the effect in in vivo. In the present study, we first studied the effect of YKS and UH on aggressiveness and sociality in socially isolated mice. YKS and UH ameliorated the isolation-induced increased aggressiveness and decreased sociality, and these ameliorative effects were counteracted by coadministration of 5-HT(1A) receptor antagonist WAY-100635, or disappeared by eliminating UH from YKS. These results suggest that the effect of YKS is mainly attributed to UH, and the active ingredient is contained in UH. To find the candidate ingredients, we examined competitive binding assay and [(35)S] guanosine 5'-O-(3-thiotriphosphate) (GTPγS) binding assay of seven major alkaloids in UH using Chinese hamster ovary cells expressing 5-HT(1A) receptors artificially. Only geissoschizine methyl ether (GM) among seven alkaloids potently bound to 5-HT(1A) receptors and acted as a partial agonist. This in vitro result on GM was further demonstrated in the socially isolated mice. As did YKS and UH, GM ameliorated the isolation-induced increased aggressiveness and decreased sociality, and the effect was counteracted by coadministration of WAY-100635. These lines of results suggest that GM in UH is potent 5-HT(1A) receptor agonist and a candidate for pharmacological effect of YKS on aggressiveness and sociality in socially isolated mice.

Systematic analysis of emotionality in consomic mouse strains established from C57BL/6J and wild-derived MSM/Ms

Consomic strains have recently attracted attention as an advantageous method to screen for genes related to developmental, physiological, and behavioral phenotypes. Recently, a new set of consomic strains was established from the Japanese wild-derived mouse strain MSM/Ms and C57BL/6JJcl. By analyzing the entire consomic panel, we were able to identify a number of chromosomes associated with anxiety-like behaviors in the open-field (OF) test, a light-dark box and an elevated plus maze. Detailed observation of the OF behavior allowed us to identify chromosomes associated with those ethological traits, such as stretch attend, rearing, and jumping. Repeated OF test trials have different meanings for animals, and we found that some chromosomes responded to only the first or second trial, while others were consistent across both trials. By examining both male and female mice, sex-dependent effects were found in several measurements. Principal component analysis of anxiety-like behaviors extracted five factors: 'general locomotor activity', 'thigmotaxis', 'risk assessment', 'open-arm exploration' and 'autonomic emotionality'. We mapped chromosomes associated with these five factors of emotionality.

Mutation of the plastidial alpha-glucan phosphorylase gene in rice affects the synthesis and structure of starch in the endosperm

Plastidial phosphorylase (Pho1) accounts for approximately 96% of the total phosphorylase activity in developing rice (Oryza sativa) seeds. From mutant stocks induced by N-methyl-N-nitrosourea treatment, we identified plants with mutations in the Pho1 gene that are deficient in Pho1. Strikingly, the size of mature seeds and the starch content in these mutants showed considerable variation, ranging from shrunken to pseudonormal. The loss of Pho1 caused smaller starch granules to accumulate and modified the amylopectin structure. Variation in the morphological and biochemical phenotype of individual seeds was common to all 15 pho1-independent homozygous mutant lines studied, indicating that this phenotype was caused solely by the genetic defect. The phenotype of the pho1 mutation was temperature dependent. While the mutant plants grown at 30 degrees C produced mainly plump seeds at maturity, most of the seeds from plants grown at 20 degrees C were shrunken, with a significant proportion showing severe reduction in starch accumulation. These results strongly suggest that Pho1 plays a crucial role in starch biosynthesis in rice endosperm at low temperatures and that one or more other factors can complement the function of Pho1 at high temperatures.

Characterization of SSIIIa-deficient mutants of rice: the function of SSIIIa and pleiotropic effects by SSIIIa deficiency in the rice endosperm

Starch synthase IIIa (SSIIIa)-deficient rice (Oryza sativa) mutants were generated using retrotransposon insertion and chemical mutagenesis. The lowest migrating SS activity bands on glycogen-containing native polyacrylamide gel, which were identified to be those for SSIIIa, were completely absent in these mutants, indicating that they are SSIIIa null mutants. The amylopectin B(2) to B(4) chains with degree of polymerization (DP) >/= 30 and the M(r) of amylopectin in the mutant were reduced to about 60% and 70% of the wild-type values, respectively, suggesting that SSIIIa plays an important part in the elongation of amylopectin B(2) to B(4) chains. Chains with DP 6 to 9 and DP 16 to 19 decreased while chains with DP 10 to 15 and DP 20 to 25 increased in the mutants amylopectin. These changes in the SSIIIa mutants are almost opposite images of those of SSI-deficient rice mutant and were caused by 1.3- to 1.7-fold increase of the amount of SSI in the mutants endosperm. Furthermore, the amylose content and the extralong chains (DP >/= 500) of amylopectin were increased by 1.3- and 12-fold, respectively. These changes in the composition in the mutants starch were caused by 1.4- to 1.7-fold increase in amounts of granules-bound starch synthase (GBSSI). The starch granules of the mutants were smaller with round shape, and were less crystalline. Thus, deficiency in SSIIIa, the second major SS isozyme in developing rice endosperm affected the structure of amylopectin, amylase content, and physicochemical properties of starch granules in two ways: directly by the SSIIIa deficiency itself and indirectly by the enhancement of both SSI and GBSSI gene transcripts.

Role of adenosine A1 receptors in the modulation of dopamine D1 and adenosine A2a receptor signaling in the neostriatum

Adenosine is known to modulate the function of neostriatal neurons. Adenosine acting on A(2A) receptors increases the phosphorylation of dopamine- and cAMP-regulated phosphoprotein of M(r) 32 kDa (DARPP-32) at Thr34 (the cAMP-dependent protein kinase [PKA] site) in striatopallidal neurons, and opposes dopamine D2 receptor signaling. In contrast, the role of adenosine A(1) receptors in the regulation of dopamine/DARPP-32 signaling is not clearly understood. Here, we investigated the effect of adenosine A(1) receptors on D(1), D(2) and A(2A) receptor signaling using mouse neostriatal slices. An A(1) receptor agonist, 2-chloro-N(6)-cyclopentyladenosine (100 nM), caused a transient increase, followed by a transient decrease, in DARPP-32 Thr34 phosphorylation. Our data support the following model for the actions of the A(1) receptor agonist. The A(1) receptor-induced early increase in Thr34 phosphorylation was mediated by presynaptic inhibition of dopamine release, and the subsequent removal of tonic inhibition by D(2) receptors of A(2A) receptor/G(olf)/cAMP/PKA signaling. The A(1) receptor-induced late decrease in Thr34 phosphorylation was mediated by a postsynaptic G(i) mechanism, resulting in inhibition of D(1) and A(2A) receptor-coupled G(olf)/cAMP/PKA signaling in direct and indirect pathway neurons, respectively. In conclusion, A(1) receptors play a major modulatory role in dopamine and adenosine receptor signaling.

Engineering a hybrid pseudomonad to acquire 3,4-dioxygenase activity for polychlorinated biphenyls

We constructed a hybrid strain that acquired 3,4-dioxygenase activity for polychlorinated biphenyls (PCBs). This strain, KF707-D34, possessed a chimeric biphenyl dioxygenase gene, of which a portion of bphA1 (coding for a large subunit of biphenyl dioxygenase) of Pseudomonas pseudoalcaligenes KF707 was replaced with that of a PCB-degrader, Burkholderia cepacia LB400 by homologous recombination. KF707-D34 retained the ability to degrade 4,4'-dichlorobiphenyl via 2,3-dioxygenation in a fashion identical to that of KF707 and gained novel capability to degrade 2,5,4'-trichlorobiphenyl and 2,5,2',5'-tetrachlorobiphenyl via 3,4-dioxygenation in a fashion identical to that of LB400. Sequence analysis of bphA1 from KF707-D34 revealed that three nucleotides in the 3'-terminal region of KF707 bphA1 were changed to correspond to those in LB400 bphA1. The resulting BphA1 protein in KF707-D34 was changed at position 376 from threonine (Thr) to asparagine (Asn). The results demonstrate that a minor alteration of the amino acid sequence in BphA1 improved the PCB degradation capability in biphenyl-utilizing bacteria.

A network of control mediated by regulator of calcium/calmodulin-dependent signaling

Calmodulin (CaM) is a major effector for the intracellular actions of Ca2+ in nearly all cell types. We identified a CaM-binding protein, designated regulator of calmodulin signaling (RCS). G protein-coupled receptor (GPCR)-dependent activation of protein kinase A (PKA) led to phosphorylation of RCS at Ser55 and increased its binding to CaM. Phospho-RCS acted as a competitive inhibitor of CaM-dependent enzymes, including protein phosphatase 2B (PP2B, also called calcineurin). Increasing RCS phosphorylation blocked GPCR- and PP2B-mediated suppression of L-type Ca2+ currents in striatal neurons. Conversely, genetic deletion of RCS significantly increased this modulation. Through a molecular mechanism that amplifies GPCR- and PKA-mediated signaling and attenuates GPCR- and PP2B-mediated signaling, RCS synergistically increases the phosphorylation of key proteins whose phosphorylation is regulated by PKA and PP2B.

The structure of starch can be manipulated by changing the expression levels of starch branching enzyme IIb in rice endosperm

When the starch branching enzyme IIb (BEIIb) gene was introduced into a BEIIb-defective mutant, the resulting transgenic rice plants showed a wide range of BEIIb activity and the fine structure of their amylopectins showed considerable variation despite having the two other BE isoforms, BEI and BEIIa, in their endosperm at the same levels as in the wild-type. The properties of the starch granules, such as their gelatinization behaviour, morphology and X-ray diffraction pattern, also changed dramatically depending on the level of BEIIb activity, even when this was either slightly lower or higher than that of the wild-type. The over-expression of BEIIb resulted in the accumulation of excessive branched, water-soluble polysaccharides instead of amylopectin. These results imply that the manipulation of BEIIb activity is an effective strategy for the generation of novel starches for use in foodstuffs and industrial applications.

Starch-branching enzyme I-deficient mutation specifically affects the structure and properties of starch in rice endosperm

We have isolated a starch mutant that was deficient in starch-branching enzyme I (BEI) from the endosperm mutant stocks of rice (Oryza sativa) induced by the treatment of fertilized egg cells with N-methyl-N-nitrosourea. The deficiency of BEI in this mutant was controlled by a single recessive gene, tentatively designated as starch-branching enzyme mutant 1 (sbe1). The mutant endosperm exhibited the normal phenotype and contained the same amount of starch as the wild type. However, the mutation apparently altered the fine structure of amylopectin. The mutant amylopectin was characterized by significant decrease in both long chains with degree of polymerization (DP) > or = 37 and short chains with DP 12 to 21, marked increase in short chains with DP < or = 10 (A chains), and slight increase in intermediate chains with DP 24 to 34, suggesting that BEI specifically synthesizes B1 and B2-3 chains. The endosperm starch from the sbe1 mutant had a lower onset concentration for urea gelatinization and a lower onset temperature for thermo-gelatinization compared with the wild type, indicating that the genetic modification of amylopectin fine structure is responsible for changes in physicochemical properties of sbe1 starch.

Biochemical and genetic analysis of the effects of amylose-extender mutation in rice endosperm

Biochemical analysis of amylose-extender (ae) mutant of rice (Oryza sativa) revealed that the mutation in the gene for starch-branching enzyme IIb (BEIIb) specifically altered the structure of amylopectin in the endosperm by reducing short chains with degree of polymerization of 17 or less, with the greatest decrease in chains with degree of polymerization of 8 to 12. The extent of such change was correlated with the gelatinization properties of the starch granules, as determined in terms of solubility in urea solution. The ae mutation caused a dramatic reduction in the activity of BEIIb. The activity of soluble starch synthase I (SSI) in the ae mutant was significantly lower than in the wild type, suggesting that the mutation had a pleiotropic effect on the SSI activity. In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation. Therefore, it is stressed that the function of BEIIb cannot be complemented by BEIIa and BEI. These results strongly suggest that BEIIb plays a specific role in the transfer of short chains, which might then be extended by SS to form the A and B(1) chains of amylopectin cluster in rice endosperm.

Biochemical and genetic analysis of the effects of amylose-extender mutation in rice endosperm

Biochemical analysis of amylose-extender (ae) mutant of rice (Oryza sativa) revealed that the mutation in the gene for starch-branching enzyme IIb (BEIIb) specifically altered the structure of amylopectin in the endosperm by reducing short chains with degree of polymerization of 17 or less, with the greatest decrease in chains with degree of polymerization of 8 to 12. The extent of such change was correlated with the gelatinization properties of the starch granules, as determined in terms of solubility in urea solution. The ae mutation caused a dramatic reduction in the activity of BEIIb. The activity of soluble starch synthase I (SSI) in the ae mutant was significantly lower than in the wild type, suggesting that the mutation had a pleiotropic effect on the SSI activity. In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation. Therefore, it is stressed that the function of BEIIb cannot be complemented by BEIIa and BEI. These results strongly suggest that BEIIb plays a specific role in the transfer of short chains, which might then be extended by SS to form the A and B(1) chains of amylopectin cluster in rice endosperm.

Biochemical and genetic analysis of the effects of amylose-extender mutation in rice endosperm

Biochemical analysis of amylose-extender (ae) mutant of rice (Oryza sativa) revealed that the mutation in the gene for starch-branching enzyme IIb (BEIIb) specifically altered the structure of amylopectin in the endosperm by reducing short chains with degree of polymerization of 17 or less, with the greatest decrease in chains with degree of polymerization of 8 to 12. The extent of such change was correlated with the gelatinization properties of the starch granules, as determined in terms of solubility in urea solution. The ae mutation caused a dramatic reduction in the activity of BEIIb. The activity of soluble starch synthase I (SSI) in the ae mutant was significantly lower than in the wild type, suggesting that the mutation had a pleiotropic effect on the SSI activity. In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation. Therefore, it is stressed that the function of BEIIb cannot be complemented by BEIIa and BEI. These results strongly suggest that BEIIb plays a specific role in the transfer of short chains, which might then be extended by SS to form the A and B(1) chains of amylopectin cluster in rice endosperm.

Biochemical and genetic analysis of the effects of amylose-extender mutation in rice endosperm

Biochemical analysis of amylose-extender (ae) mutant of rice (Oryza sativa) revealed that the mutation in the gene for starch-branching enzyme IIb (BEIIb) specifically altered the structure of amylopectin in the endosperm by reducing short chains with degree of polymerization of 17 or less, with the greatest decrease in chains with degree of polymerization of 8 to 12. The extent of such change was correlated with the gelatinization properties of the starch granules, as determined in terms of solubility in urea solution. The ae mutation caused a dramatic reduction in the activity of BEIIb. The activity of soluble starch synthase I (SSI) in the ae mutant was significantly lower than in the wild type, suggesting that the mutation had a pleiotropic effect on the SSI activity. In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation. Therefore, it is stressed that the function of BEIIb cannot be complemented by BEIIa and BEI. These results strongly suggest that BEIIb plays a specific role in the transfer of short chains, which might then be extended by SS to form the A and B(1) chains of amylopectin cluster in rice endosperm.

Regulation of cyclin-dependent kinase 5 and casein kinase 1 by metabotropic glutamate receptors

Cyclin-dependent kinase 5 (Cdk5) is a multifunctional neuronal protein kinase that is required for neurite outgrowth and cortical lamination and that plays an important role in dopaminergic signaling in the neostriatum through phosphorylation of Thr-75 of DARPP-32 (dopamine and cAMP-regulated phosphoprotein, molecular mass 32 kDa). Casein kinase 1 (CK1) has been implicated in a variety of cellular functions such as DNA repair, circadian rhythm, and intracellular trafficking. In the neostriatum, CK1 has been found to phosphorylate Ser-137 of DARPP-32. However, first messengers for the regulation of Cdk5 or CK1 have remained unknown. Here we report that both Cdk5 and CK1 are regulated by metabotropic glutamate receptors (mGluRs) in neostriatal neurons. (S)-3,5-dihydroxyphenylglycine (DHPG), an agonist for group I mGluRs, increased Cdk5 and CK1 activities in neostriatal slices, leading to the enhanced phosphorylation of Thr-75 and Ser-137 of DARPP-32, respectively. The effect of DHPG on Thr-75, but not on Ser-137, was blocked by a Cdk5-specific inhibitor, butyrolactone. In contrast, the effects of DHPG on both Thr-75 and Ser-137 were blocked by CK1-7 and IC261, specific inhibitors of CK1, suggesting that activation of Cdk5 by mGluRs requires CK1 activity. In support of this possibility, the DHPG-induced increase in Cdk5 activity, measured in extracts of neostriatal slices, was abolished by CK1-7 and IC261. Treatment of acutely dissociated neurons with DHPG enhanced voltage-dependent Ca(2+) currents. This enhancement was eliminated by either butyrolactone or CK1-7 and was absent in DARPP-32 knockout mice. Together these results indicate that a CK1-Cdk5-DARPP-32 cascade may be involved in the regulation by mGluR agonists of Ca(2+) channels.

Liver abscess caused by Clostridium difficile

We report the first case of an infected cyst and liver abscess caused by Clostridium difficile. It recurred 11 months later, despite therapy with vancomycin and percutaneous drainage. Administration of metronidazole following percutaneous drainage achieved a favorable outcome.

Phosphorylation of protein phosphatase inhibitor-1 by Cdk5

Protein phosphatase inhibitor-1 is a prototypical mediator of cross-talk between protein kinases and protein phosphatases. Activation of cAMP-dependent protein kinase results in phosphorylation of inhibitor-1 at Thr-35, converting it into a potent inhibitor of protein phosphatase-1. Here we report that inhibitor-1 is phosphorylated in vitro at Ser-67 by the proline-directed kinases, Cdk1, Cdk5, and mitogen-activated protein kinase. By using phosphorylation state-specific antibodies and selective protein kinase inhibitors, Cdk5 was found to be the only kinase that phosphorylates inhibitor-1 at Ser-67 in intact striatal brain tissue. In vitro and in vivo studies indicated that phospho-Ser-67 inhibitor-1 was dephosphorylated by protein phosphatases-2A and -2B. The state of phosphorylation of inhibitor-1 at Ser-67 was dynamically regulated in striatal tissue by glutamate-dependent regulation of N-methyl-d-aspartic acid-type channels. Phosphorylation of Ser-67 did not convert inhibitor-1 into an inhibitor of protein phosphatase-1. However, inhibitor-1 phosphorylated at Ser-67 was a less efficient substrate for cAMP-dependent protein kinase. These results demonstrate regulation of a Cdk5-dependent phosphorylation site in inhibitor-1 and suggest a role for this site in modulating the amplitude of signal transduction events that involve cAMP-dependent protein kinase activation.

Effects of chronic exposure to cocaine are regulated by the neuronal protein Cdk5

Cocaine enhances dopamine-mediated neurotransmission by blocking dopamine re-uptake at axon terminals. Most dopamine-containing nerve terminals innervate medium spiny neurons in the striatum of the brain. Cocaine addiction is thought to stem, in part, from neural adaptations that act to maintain equilibrium by countering the effects of repeated drug administration. Chronic exposure to cocaine upregulates several transcription factors that alter gene expression and which could mediate such compensatory neural and behavioural changes. One such transcription factor is DeltaFosB, a protein that persists in striatum long after the end of cocaine exposure. Here we identify cyclin-dependent kinase 5 (Cdk5) as a downstream target gene of DeltaFosB by use of DNA array analysis of striatal material from inducible transgenic mice. Overexpression of DeltaFosB, or chronic cocaine administration, raised levels of Cdk5 messenger RNA, protein, and activity in the striatum. Moreover, injection of Cdk5 inhibitors into the striatum potentiated behavioural effects of repeated cocaine administration. Our results suggest that changes in Cdk5 levels mediated by DeltaFosB, and resulting alterations in signalling involving D1 dopamine receptors, contribute to adaptive changes in the brain related to cocaine addiction.

XAFS study on active Pr sites in zeolite as a photocatalyst for decomposition of nitrous oxide

The praseodymium-exchanged mordenite degassed at 873 K acted as a highly active heterogeneous photocatalyst for the stoichiometric decomposition of N2O. Analysis of Pr L3-edge EXAFS revealed that the Pr species were isolated each other in the large channel of zeolite, and that the active Pr species were coordinated by ca. four oxygen atoms and one Al atom. On the other hands, the inactive Pr species are surrounded by ca. 10 oxygens of adsorbed waters. The former low-coordinated Pr species allowed a strong adsorption of N2O, which could be the first step of the decomposition reaction.

Biliary atresia with extrahepatic biliary cysts--cholangiographic patterns influencing the prognosis

PURPOSE

Biliary atresia (BA) with extrahepatic biliary cysts (EHBC) has been recognized generally as "correctable" BA, which indicates a good prognosis. The variants of BA with EHBC according to cholangiographic findings and their outcomes were reviewed.

METHODS

An EHBC was observed in 8 (20%) of 40 patients with BA who underwent operation at our institute. Intraoperative cholangiographic patterns included visualization of the intrahepatic bile ducts (type I BA with EHBC) in 6 patients and no visualization (type III BA with EHBC) in 2. Intrahepatic biliary cysts (IHBC) and EHBC were observed simultaneously in 2 patients diagnosed at older age. The follow-up periods ranged between 4 months and 20 years.

RESULTS

Good bile drainage after a hepaticoenterostomy or portoenterostomy was obtained in all 6 patients with type I BA with EHBC. Two who showed IHBC on intraoperative cholangiography had complications caused by postoperative recurrent cholangitis, which led to a liver transplantation in 1. Revision after the portoenterostomy was required in 2 patients with type III BA with EHBC. One became jaundice free after revision, whereas the other died of hepatic failure without bile drainage.

CONCLUSION

Intraoperative cholangiographic findings showing IHBC and type III BA are poor prognostic factors in patients with BA with EHBC.

Phosphorylation of protein phosphatase-1 inhibitors, inhibitor-1 and DARPP-32, in renal medulla

Inhibitor-1 and DARPP-32 (dopamine and cAMP-regulated phosphoprotein, Mr 32 kDa) are each phosphorylated by cAMP-dependent protein kinase, resulting in their conversion to potent inhibitors of protein phosphatase-1. Protein phosphatase-1 is involved in the regulation of Na(+) reabsorption from renal tubule by modulating the activity of Na(+),K(+)-ATPase. In this study, we have investigated the regulation of inhibitor-1 and DARPP-32 phosphorylation in slices of renal medulla. Activation of cAMP-dependent protein kinase by forskolin and 8-bromo-cAMP increased the level of phosphorylated inhibitor-1. Okadaic acid (1 microM), used to inhibit protein phosphatase-2A, increased the level of phosphorylated inhibitor-1, but cyclosporin A had no effect. DARPP-32, like inhibitor-1, was phosphorylated by cAMP-dependent protein kinase and dephosphorylated only by protein phosphatase-2A. These data demonstrate that the phosphorylation of inhibitor-1 and DARPP-32 is regulated by the balance of phosphorylation by cAMP-dependent protein kinase and dephosphorylation by protein phosphatase-2A in renal medulla. Furthermore, the phosphorylation step is regulated by pharmacological stimuli such as activation of beta(1)-adrenoceptors and dopamine D1 receptors.

Amplification of dopaminergic signaling by a positive feedback loop

Dopamine and cAMP-regulated phosphoprotein of M(r) 32,000 (DARPP-32) plays an obligatory role in most of the actions of dopamine. In resting neostriatal slices, cyclin-dependent kinase 5 (Cdk5) phosphorylates DARPP-32 at Thr-75, thereby reducing the efficacy of dopaminergic signaling. We report here that dopamine, in slices, and acute cocaine, in whole animals, decreases the state of phosphorylation of striatal DARPP-32 at Thr-75 and thereby removes this inhibitory constraint. This effect of dopamine is achieved through dopamine D1 receptor-mediated activation of cAMP-dependent protein kinase (PKA). The activated PKA, by decreasing the state of phosphorylation of DARPP-32-Thr-75, de-inhibits itself. Dopamine D2 receptor stimulation has the opposite effect. The ability of activated PKA to reduce the state of phosphorylation of DARPP-32-Thr-75 is apparently attributable to increased protein phosphatase-2A activity, with Cdk5 being unaffected. Together, these results indicate that via positive feedback mechanisms, Cdk5 signaling and PKA signaling are mutually antagonistic.

A 90-kilobase conjugative chromosomal element coding for biphenyl and salicylate catabolism in Pseudomonas putida KF715

The biphenyl and salicylate metabolic pathways in Pseudomonas putida KF715 are chromosomally encoded. The bph gene cluster coding for the conversion of biphenyl to benzoic acid and the sal gene cluster coding for the salicylate meta-pathway were obtained from the KF715 genomic cosmid libraries. These two gene clusters were separated by 10-kb DNA and were highly prone to deletion when KF715 was grown in nutrient medium. Two types of deletions took place at the region including only the bph genes (ca. 40 kb) or at the region including both the bph and sal genes (ca. 70 kb). A 90-kb DNA region, including both the bph and sal genes (termed the bph-sal element), was transferred by conjugation from KF715 to P. putida AC30. Such transconjugants gained the ability to grow on biphenyl and salicylate as the sole sources of carbon. The bph and sal element was located on the chromosome of the recipient. The bph-sal element in strain AC30 was also highly prone to deletion; however, it could be mobilized to the chromosome of P. putida KT2440 and the two deletion mutants of KF715.

Phosphorylation of DARPP-32 by Cdk5 modulates dopamine signalling in neurons

The physiological state of the cell is controlled by signal transduction mechanisms which regulate the balance between protein kinase and protein phosphatase activities. Here we report that a single protein can, depending on which particular amino-acid residue is phosphorylated, function either as a kinase or phosphatase inhibitor. DARPP-32 (dopamine and cyclic AMP-regulated phospho-protein, relative molecular mass 32,000) is converted into an inhibitor of protein phosphatase 1 when it is phosphorylated by protein kinase A (PKA) at threonine 34. We find that DARPP-32 is converted into an inhibitor of PKA when phosphorylated at threonine 75 by cyclin-dependent kinase 5 (Cdk5). Cdk5 phosphorylates DARPP-32 in vitro and in intact brain cells. Phospho-Thr 75 DARPP-32 inhibits PKA in vitro by a competitive mechanism. Decreasing phospho-Thr 75 DARPP-32 in striatal slices, either by a Cdk5-specific inhibitor or by using genetically altered mice, results in increased dopamine-induced phosphorylation of PKA substrates and augmented peak voltage-gated calcium currents. Thus DARPP-32 is a bifunctional signal transduction molecule which, by distinct mechanisms, controls a serine/threonine kinase and a serine/threonine phosphatase.

Regulation of Na+, K+-ATPase isoforms in rat neostriatum by dopamine and protein kinase C

Our previous studies showed that dopamine inhibits Na+,K+-ATPase activity in acutely dissociated neurons from striatum. In the present study, we have found that in this preparation, dopamine inhibited significantly (by approximately 25%) the activity of the alpha3 and/or alpha2 isoforms, but not the alpha1 isoform, of Na+,K+-ATPase. Dopamine, via D1 receptors, activates cyclic AMP-dependent protein kinase (PKA) in striatal neurons. Dopamine is also known to activate the calcium- and phospholipid-dependent protein kinase (PKC) in a number of different cell types. The PKC activator phorbol 12,13-dibutyrate reduced the activity of Na+,K+-ATPase alpha3 and/or alpha2 isoforms (by approximately 30%) as well as the alpha1 isoform (by approximately 15%). However, dopamine-mediated inhibition of Na+,K+-ATPase activity was unaffected by calphostin C, a PKC inhibitor. Dopamine did not affect the phosphorylation of Na+,K+-ATPase isoforms at the PKA-dependent phosphorylation site. Phorbol ester treatment did not alter the phosphorylation of alpha2 or alpha3 isoforms of Na+,K+-ATPase in neostriatal neurons but did increase the phosphorylation of the alpha1 isoform. Thus, in rat neostriatal neurons, treatment with either dopamine or PKC activators results in inhibition of the activity of specific (alpha3 and/or alpha2) isoforms of Na+,K+-ATPase, but this is not apparently mediated through direct phosphorylation of the enzyme. In addition, PKC is unlikely to mediate inhibition of rat Na+,K+-ATPase activity by dopamine in neostriatal neurons.

Requirement for DARPP-32 in mediating effect of dopamine D2 receptor activation

It is well documented that dopamine and dopamine D1 agonists convert the protein phosphatase-1 inhibitor, DARPP-32, from its dephosphorylated, inactive form into its Thr34-phosphorylated, active form, and that these effects on DARPP-32 constitute essential components of the mechanism by which dopamine and D1 agonists achieve their biological effects. In contrast to dopamine and D1 agonists, dopamine D2 agonists dephosphorylate and inactivate DARPP-32. Here we have examined the possibility that the biological effects of dopamine D2 receptor agonists might also involve DARPP-32. For this purpose, we have examined regulation of the activity of the electrogenic ion pump Na+,K+-ATPase, an established target for dopamine signalling. We have found that dopamine D1 agonists and dopamine D2 agonists inhibit Na+,K+-ATPase activity in dissociated cells from the mouse neostriatum and that, in each case, the effect is abolished in cells from mice deficient in DARPP-32. We conclude that DARPP-32 may play an obligatory role in dopaminergic signalling mediated both by D1 receptors and by D2 receptors.

Role of calcineurin and protein phosphatase-2A in the regulation of DARPP-32 dephosphorylation in neostriatal neurons

DARPP-32, a dopamine- and cyclic AMP-regulated phosphoprotein of Mr 32 kDa, is phosphorylated on Thr34 by cyclic AMP-dependent protein kinase, resulting in its conversion to a potent inhibitor of protein phosphatase-1 (PP-1). Conversely, Thr34-phosphorylated DARPP-32 is dephosphorylated and inactivated in vitro by calcineurin and protein phosphatase-2A (PP-2A). We have investigated the relative contributions of these protein phosphatases to the regulation of DARPP-32 dephosphorylation in mouse neostriatal slices. Cyclosporin A (5 microM), a calcineurin inhibitor, maximally increased the level of phosphorylated DARPP-32 by 17+/-2-fold. Okadaic acid (1 microM), an inhibitor of PP-1 and PP-2A, had a smaller effect, increasing phospho-DARPP-32 by 5.1+/-1.3-fold. The effect of okadaic acid on DARPP-32 phosphorylation was shown to be due to inhibition of PP-2A activity. Incubation of slices in the presence of cyclosporin A plus either okadaic acid or calyculin A, another PP-1/PP-2A inhibitor, caused a synergistic increase in the level of phosphorylated DARPP-32. The use of Ca2(+)-free/EGTA medium mimicked the effects of cyclosporin A on DARPP-32 phosphorylation, supporting the conclusion that the action of cyclosporin on DARPP-32 phosphorylation was attributable to blockade of the Ca2(+)-dependent activation of calcineurin. The results indicate that calcineurin and PP-2A, but not PP-1, act synergistically to maintain a low level of phosphorylated DARPP-32 in neostriatal slices.

Mobile catabolic genes in bacteria

The recent findings of various mobile catabolic genes have provided some insight into the evolution of microbial degradation systems for xenobiotic compounds. The catabolic genes undergo marked genetic rearrangements due to their presence on transposons or association with mobile genetic elements. Bacterial catabolic transposons fall into three defined structural classes. Class I elements include catabolic genes flanked by two copies of insertion sequences. Class II elements carry short terminal inverted repeats and transpose by the replicative mode in which transposase and resolvase are involved. Conjugative catabolic transposons represent the third class of mobile genetic elements. They carry all the genes required for excision, conjugal transfer to a new host, and integration. This review focuses on the structures, functions and roles of the recently characterized catabolic transposons in bacteria. Also described are the mobile catabolic elements that share structural similarity with the pathogenicity and symbiosis islands.

DARPP-32: regulator of the efficacy of dopaminergic neurotransmission

Dopaminergic neurons exert a major modulatory effect on the forebrain. Dopamine and adenosine 3',5'-monophosphate-regulated phosphoprotein (32 kilodaltons) (DARPP-32), which is enriched in all neurons that receive a dopaminergic input, is converted in response to dopamine into a potent protein phosphatase inhibitor. Mice generated to contain a targeted disruption of the DARPP-32 gene showed profound deficits in their molecular, electrophysiological, and behavioral responses to dopamine, drugs of abuse, and antipsychotic medication. The results show that DARPP-32 plays a central role in regulating the efficacy of dopaminergic neurotransmission.

Bidirectional regulation of DARPP-32 phosphorylation by dopamine

Dopamine has been shown to stimulate phosphorylation of DARPP-32, a phosphoprotein highly enriched in medium-sized spiny neurons of the neostriatum. Here, we investigated the contribution of D1-like and D2-like dopamine receptors in the regulation of DARPP-32 phosphorylation in mouse striatal slices. D1-like and D2-like receptors had opposing effects on the state of DARPP-32 phosphorylation. The D1 receptor agonist SKF82526 increased DARPP-32 phosphorylation. In contrast, the D2 receptor agonist quinpirole decreased basal as well as D1 agonist-, forskolin-, and 8-bromo-cAMP-stimulated phosphorylation of DARPP-32. The ability of quinpirole to decrease D1-stimulated DARPP-32 phosphorylation was calcium-dependent and was blocked by the calcineurin inhibitor cyclosporin A, suggesting that the D2 effect involved an increase in intracellular calcium and activation of calcineurin. In support of this interpretation, Ca2+-free/EGTA medium induced a greater than 60-fold increase in DARPP-32 phosphorylation and abolished the ability of quinpirole to dephosphorylate DARPP-32. The antipsychotic drug raclopride, a selective D2 receptor antagonist, increased phosphorylation of DARPP-32 under basal conditions and in D2 agonist-treated slices. The results of this study demonstrate that dopamine exerts a bidirectional control on the state of phosphorylation of DARPP-32.

Functional analyses of a variety of chimeric dioxygenases constructed from two biphenyl dioxygenases that are similar structurally but different functionally

The biphenyl dioxygenases (BP Dox) of strains Pseudomonas pseudoalcaligenes KF707 and Pseudomonas cepacia LB400 exhibit a distinct difference in substrate ranges of polychlorinated biphenyls (PCB) despite nearly identical amino acid sequences. The range of congeners oxidized by LB400 BP Dox is much wider than that oxidized by KF707 BP Dox. The PCB degradation abilities of these BP Dox were highly dependent on the recognition of the chlorinated rings and the sites of oxygen activation. The KF707 BP Dox recognized primarily the 4'-chlorinated ring (97%) of 2,5,4'-trichlorobiphenyl and introduced molecular oxygen at the 2',3' position. The LB400 BP Dox recognized primarily the 2,5-dichlorinated ring (95%) of the same compound and introduced O2 at the 3,4 position. It was confirmed that the BphA1 subunit (iron-sulfur protein of terminal dioxygenase encoded by bphA1) plays a crucial role in determining the substrate selectivity. We constructed a variety of chimeric bphA1 genes by exchanging four common restriction fragments between the KF707 bphA1 and the LB400 bphA1. Observation of Escherichia coli cells expressing various chimeric BP Dox revealed that a relatively small number of amino acids in the carboxy-terminal half (among 20 different amino acids in total) are involved in the recognition of the chlorinated ring and the sites of dioxygenation and thereby are responsible for the degradation of PCB. The site-directed mutagenesis of Thr-376 (KF707) to Asn-376 (LB400) in KF707 BP Dox resulted in the expansion of the range of biodegradable PCB congeners.