Effects of the order of exposure to antimicrobials on the incidence of multidrug-resistant Pseudomonas aeruginosa

Multidrug-resistant Pseudomonas aeruginosa (MDRP) is one of the most important pathogens in clinical practice. To clarify the mechanisms contributing to its emergence, we isolated MDRPs using the P. aeruginosa PAO1, the whole genome sequence of which has already been elucidated. Mutant strains resistant to carbapenems, aminoglycosides, and new quinolones, which are used to treat P. aeruginosa infections, were isolated; however, none met the criteria for MDRPs. Then, PAO1 strains were exposed to these antimicrobial agents in various orders and the appearance rate of MDRP varied depending on the order of exposure; MDRPs more frequently appeared when gentamicin was applied before ciprofloxacin, but were rarely isolated when ciprofloxacin was applied first. Exposure to ciprofloxacin followed by gentamicin increased the expression of MexCD-OprJ, an RND-type multidrug efflux pump, due to the NfxB mutation. In contrast, exposure to gentamicin followed by ciprofloxacin resulted in more mutations in DNA gyrase. These results suggest that the type of quinolone resistance mechanism is related to the frequency of MDRP and that the risk of MDRP incidence is highly dependent on the order of exposure to gentamicin and ciprofloxacin.

Whole-Genome and Plasmid Comparative Analysis of Campylobacter jejuni from Human Patients in Toyama, Japan, from 2015 to 2019

Campylobacter jejuni is a major causative agent of food poisoning, and increasing antimicrobial resistance is a concern. This study investigated 116 clinical isolates of C. jejuni from Toyama, Japan, which were isolated from 2015 to 2019. Antimicrobial susceptibility testing and whole-genome sequencing were used for phenotypic and genotypic characterization to compare antimicrobial resistance (AMR) profiles and phylogenic linkage. The multilocus sequence typing approach identified 37 sequence types (STs) and 15 clonal complexes (CCs), including 7 novel STs, and the high frequency CCs were CC21 (27.7%), CC48 (10.9%), and CC354 (9.9%). The AMR profiles and related resistant factors were as follows: fluoroquinolones (51.7%), mutation in quinolone resistance-determining region (QRDRs) (GyrA T86I); tetracyclines (27.6%), acquisition of tet(O); ampicillin (7.8%), harboring bla_OXA184 or a promoter mutation in bla_OXA193; aminoglycosides (1.7%), acquisition of ant(6)-Ia and aph(3')-III; chloramphenicol (0.9%), acquisition of cat. The acquired resistance genes tet(O), ant(6)-Ia, aph(3')-III, and cat were located on pTet family plasmids. Furthermore, three pTet family plasmids formed larger plasmids that incorporated additional genes such as the type IV secretion system. Sequence type 4526 (ST4526; 10.9%), which is reported only in Japan, was the most predominant, suggesting continued prevalence. This study reveals the sequences of the pTet family plasmids harbored by C. jejuni in Japan, which had been unclear, and the acquisition of the insertion sequences in a part of the pTet family plasmids. Because pTet family plasmids can be horizontally transmitted and are a major factor in acquired resistance in Campylobacter, the risk of spreading pTet that has acquired further resistance should be considered. IMPORTANCE Campylobacter jejuni is among the major causes of enteritis and diarrhea in humans in many countries. Drug-resistant Campylobacter is increasing in both developing and developed countries, and in particular, fluoroquinolone-resistant Campylobacter was one of the species included on the priority list of antibiotic-resistant bacteria. Campylobacter drug resistance surveillance is important and has been conducted worldwide. In this study, we performed whole-genome analysis of Campylobacter jejuni isolated from diarrhea patients at a hospital in Toyama, Japan. This revealed the continued prevalence of Campylobacter jejuni ST4526, which has been reported to be prevalent in Japan, and the acquisition of resistance and virulence factors in the pTet family plasmids. The diversity of pTet family plasmids, the major resistance transmission factor, is expected to potentially increase the risk of Campylobacter. The usefulness of whole-genome sequencing in Campylobacter surveillance was also demonstrated.

Construction of a Temperature-Sensitive Shuttle Vector between Lactic Acid Bacteria and Escherichia coli and Its Application to a Tn10-Based Random Mutagenesis Tool in Lactic Acid Bacteria

In the present study, we have obtained a temperature-sensitive replication mutant in the Escherichia (E.) coli-lactic acid bacterium (LAB) shuttle vector pLES003-b carrying erythromycin-resistance gene by error-prone PCR technique. Among 858 clones obtained in the construction of the random mutation libraries of pLES003-b in the ori and repA regions, three clones could grow normally at 28 °C but not at 42 °C. One of the clones was designated as pLES003-b TS1. The sequencing analysis of pLES003-b TS1 revealed that the plasmid has four substitution mutations (376G > A, 435A > T, 914C > A, and 1996T > A) and one insertional mutation (1806_1807insA). Among those mutations, substitution mutation 914C > A, which leads to a CGC-to-AGC codon change at position 44 of the RepA protein (arginine-to-serine substitution mutation: R44S in RepA), was predicted to be a cause of temperature sensitivity. Therefore, the C-to-A substitution was introduced into the repA gene in pLES003-b using a site-directed mutagenesis method, and the resultant plasmid was electroporated into a Lactobacillus (L.) plantarum cell. The resultant transformant cannot grow at 42 °C in the presence of erythromycin, which is used as a selective marker, indicating that the R44S point mutation in the RepA protein may be crucial for temperature sensitivity. Furthermore, we have developed a new plasmid as an efficient genetic engineering tool for random insertional mutagenesis in LABs using a combination of transposon Tn10 and the temperature-sensitive replication system in pLES003-b. The resultant plasmid vector, which was designated pLES-Tn10-TS1, would be useful for genetic analysis of the functional molecule in lactic acid bacterial strains.

POS0794 PREGNANCY AND CHILDBIRTH IN TAKAYASU ARTERITIS IN JAPAN – A NATIONWIDE RETROSPECTIVE STUDY

Background

Takayasu arteritis (TAK), a granulomatous large vessel vasculitis, mainly involves the aorta and its proximal branches and commonly occurs in young females. However, studies of pregnancy in women with TAK are sparse and limited, probably due to the rarity of the disease.

Objectives

The purpose of this study was to understand the status quo of medical treatments of the primary disease and outcomes of pregnancy in patients with TAK, and birth outcomes of the children in Japan.

Methods

Patients with TAK who conceived after the onset of the disease and were managed at medical facilities participating in the Japan Research Committee of the Ministry of Health, Labour, and Welfare for Intractable Vasculitis (JPVAS) were retrospectively enrolled in this study. The following information was collected from patients who had a live-born baby: age at diagnosis of TAK, disease classification, age at delivery, treatments before and during pregnancy, complications during pregnancy, birth outcomes of the children, and changes in disease activity during pregnancy and after delivery.

Results

Fifty-one cases and 69 pregnancies from 19 ethics committee-approved centers were enrolled during the study period 2019–2021. Of these, 49 cases and 66 pregnancies (95.7%) resulted in delivery and live-born babies. The Numano classification of the 49 cases was as follows: type I, 11; type IIa, 15; type IIb,12; type III, 1; type IV, 1; type V, 9; with type IIa being the most common. The age of diagnosis was 22 years (13–37 years, year of diagnosis 1965–2017), the median age of the delivery of 66 pregnancies was 31 years (year of delivery 1969-2021), and the median duration of illness at delivery was nine years. There were 34 planned pregnancies (51.5%, including four pregnancies by artificial insemination/ovulation induction). Preconception therapy included prednisolone (PSL) in 51 pregnancies (77.3%, median dose 7.5 mg (range 4–30 mg)/day), immunosuppressive drugs in 18 pregnancies (27.3%, azathioprine 8, tacrolimus 7, methotrexate 4, cyclosporin A 1, and colchicine 1), biologics in 12 pregnancies (18.1%, infliximab 6, tocilizumab 5, and adalimumab 1), antihypertensive drugs in 5 pregnancies (7.6%). Surgical treatment had been performed before pregnancy in 6 cases (aortic root replacement 2, subclavian artery dilatation 1, subclavian artery bypass 1, subclavian artery stenting 1, and ascending aorta semicircular artery replacement 1). Medications used during the course of pregnancy included PSL in 48 pregnancies (72.7%, median dose 8 mg (range 4–30 mg)/day, increased in 13 pregnancies, decreased in 1 pregnancy), immunosuppressants in 13 pregnancies (19.7%, azathioprine 6, tacrolimus 6, and cyclosporin A 1), biologics 9 pregnancies (13.6%, infliximab 4, tocilizumab 4, and adalimumab 1). Immunosuppressants and biologics were discontinued in five and four pregnancies after conception. Complications during pregnancy were observed in 20 pregnancies (30.3%), with hypertension being the most common. Complications related to TAK or its treatment were severe infections in two pregnancies and aneurysm enlargement due to increased circulating plasma volume in one pregnancy. Aortic arch replacement was performed after delivery for the latter case. Relapse of TAK was observed in 4 pregnancies (6.1%) during pregnancy and in 8 pregnancies (12.1%) after delivery. One pregnancy resulted in restenosis of subclavian artery for which dilatation procedure was performed prior to the pregnancy. There were 13/66 (19.7%) preterm infants and 17/59 (28.8%) low birth weight infants; all but one had a birth weight of more than 2,000 g and no had serious postnatal abnormalities. Forty-three (82.7%) of the 52 confirmed infants were breastfeed fully or mixed.

Conclusion

Most of the pregnancies in patients with TAK were successfully delivered while they had low disease activity at a dose of less than 10 mg/day of PSL. Relapse occurred during pregnancy and after delivery in some cases. The babies tended to have low birth weight, but 82.7% of them were breastfed without serious complications.

Disclosure of Interests

Takako Miyamae: None declared, Yusuke Manabe: None declared, takahiko sugihara Speakers bureau: TS has received honoraria from Abbvie Japan Co., Ltd., AsahiKASEI Co., Ltd., Astellas Pharma Inc., Ayumi Pharmaceutical, Bristol Myers Squibb K.K., Chugai Pharmaceutical Co., Ltd., Eli Lilly Japan K.K., Mitsubishi-Tanabe Pharma Co., Ono Pharmaceutical, Pfizer Japan Inc., Takeda Pharmaceutical Co. Ltd., and UCB Japan Co., Grant/research support from: TS has received research grants from AsahiKASEI Co., Ltd., Daiichi Sankyo., Chugai Pharmaceutical Co., Ltd., and Ono Pharmaceutical., Natsuka Umezawa: None declared, Hajime Yoshifuji Speakers bureau: HY has received lecture fees from Janssen and Chugai., Naoto Tamura: None declared, Yoshiyuki Abe: None declared, Shunsuke Furuta Speakers bureau: Chugai Pharmaceutical Co.,Ltd.

DaiichiSankyo Co.,Ltd.

Asahi-Kasei Pharma Corporation, Manami Kato: None declared, Takashi Kumagai: None declared, Kaito Nakamura: None declared, Hiroko Nagafuchi: None declared, Jun Ishizaki: None declared, Naoko Nakano: None declared, Tatsuya Atsumi Speakers bureau: Mitsubishi Tanabe Pharma Co., Chugai Pharmaceutical Co., Ltd., Astellas Pharma Inc., Takeda Pharmaceutical Co., Ltd., Pfizer Inc., AbbVie Inc., Eisai Co. Ltd., Daiichi Sankyo Co., Ltd., Bristol-Myers Squibb Co., UCB Japan Co. Ltd., Eli Lilly Japan K.K., Novartis Pharma K.K., Eli Lilly Japan K.K., Kyowa Kirin Co., Ltd.,TAIHO PHARMACEUTICAL CO., LTD., Consultant of: AstraZeneca plc., MEDICAL & BIOLOGICAL LABORATORIES CO., LTD., Pfizer Inc., AbbVie Inc., ONO PHARMACEUTICAL CO. LTD.,

Novartis Pharma K.K., Nippon Boehringer Ingelheim Co., Ltd., Grant/research support from: Astellas Pharma Inc., TAIHO PHARMACEUTICAL CO., LTD.AbbVie Inc., Nippon Boehringer Ingelheim Co., Ltd.,Takeda Pharmaceutical Co., Ltd., Mitsubishi Tanabe Pharma Co., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co. Ltd., Otsuka Pharmaceutical Co., Ltd. and Pfizer Inc. Alexion Inc., TEIJIN PHARMA LIMITED., Kohei Karino: None declared, Koichi Amano Speakers bureau: AbbVie GK, Asahi-Kasei Pharma, Astellas, Chugai Pharmaceutical Co.Ltd., Eisai, Eli Lilly, GlaxoSmithKlein, Janssen Pharma, Pfizer Japan, Grant/research support from: Asahi-Kasei Pharma,Chugai Pharmaceutical Co.Ltd., Takahiko Kurasawa: None declared, Shuichi Ito: None declared, Ryusuke Yoshimi: None declared, Noriyoshi Ogawa: None declared, Shogo Banno: None declared, Taio Naniwa Speakers bureau: Chugai, Tanabe, Abbbvie, Eisai, Grant/research support from: Chugai, Tanabe, Abbbvie, Eisai, Satoshi Ito Speakers bureau: SI has received speaker’s fees from pharmaceutical companies., Akinori Hara: None declared, Shinya Hirahara: None declared, Haruhito A. Uchida: None declared, Yasuhiro Onishi: None declared, Yohko Murakawa Speakers bureau: Astellas, UCB, Chugai, AbbVie, Grant/research support from: Chugai, AbbVie, Yoshinori Komagata: None declared, Yoshikazu Nakaoka: None declared, Masayoshi Harigai Speakers bureau: MH has received speaker’s fee from AbbVie Japan GK, Ayumi Pharmaceutical Co., Boehringer Ingelheim Japan, Inc., Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Janssen Pharmaceutical K.K., Kissei Pharmaceutical Co., Ltd., Novartis Japan, Pfizer Japan Inc., Mitsubishi Tanabe Pharma Co., Teijin Pharma Ltd and UCB Japan., Consultant of: MH is a consultant for AbbVie, Boehringer-Ingelheim, Kissei Pharmaceutical Co., Ltd., and Teijin Pharma.

Effect of uric acid-lowering therapy on renal function in patients with chronic kidney disease: a systematic review and meta-analysis

Background

Whether uric acid (UA)-lowering therapy (ULT) is effective in reducing the progression of renal dysfunction in patients with chronic kidney disease (CKD) remains controversial. Since several advances have been made in therapies for hyperuricemia, including novel xanthine oxidoreductase (XOR) inhibitors, we conducted a systematic review to clarify the effectiveness of ULT in preserving renal function among CKD patients.

Methods

In this systematic review, the MEDLINE database was searched up to June 2019. We included complete randomized controlled trials comparing renal events between adult non-dialyzed CKD patients, defined as estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2, with and without ULTs. Changes in eGFR were expressed as the mean difference (MD). The incidence of dichotomous outcomes was expressed as a risk ratio. This review was performed using the predefined protocol published in PROSPERO (CRD 42019140346).

Results

Eleven studies with 4277 CKD patients were included. Drugs used in the intervention groups of all studies were XOR inhibitors (allopurinol, febuxostat or topiroxostat). Although patients with ULT tended to show superior preservation of eGFR as compared to those without ULT, no significant differences were identified (MD, 2.52; 95% confidence interval, − 0.15 to 5.18). In subgroup analysis, the use of allopurinol was associated with superior preservation of eGFR, whereas the newer XOR inhibitors, febuxostat and topiroxostat, showed no significant effects on eGFR changes. Neither incidence of end-stage kidney disease nor treatment-emergent adverse events differed significantly between groups.

Conclusions

The present systematic review and meta-analysis suggested that CKD patients with ULT tend to show superior eGFR preservation as compared to patients without ULT, but further studies are needed to verify the renoprotective effects of ULT.

Pathological assessment of osimertinib-associated cardiotoxicity in EGFR-mutated non-small cell lung cancer patients

Background

Osimertinib, a third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI), inhibits both EGFR-TKI sensitizing mutations and resistant T790M mutations detected in non-small cell lung cancer (NSCLC) patients. Cardiac adverse events (AEs) induced by osimertinib are infrequent; however, cases of severe associated cardiac dysfunction have been reported and remain poorly understood.

Purpose

To assess pathogenesis of osimertinib-associated cardiac AEs, we analyzed myocardial specimens of three NSCLC cases with osimertinib-associated cardiac dysfunction.

Results

Analysis of LVEF prior to and after osimertinb administration in 36 NSCLC patients showed significant decrease of LVEF from 69% to 63%. Within this cohort, right ventricular (RV) biopsy was performed in 2 cases to further understand the pathophysiology of cardiac dysfunction. Case 1 was 78-year-old female with advanced NSCLC harboring an EGFR L858R mutation was treated with osimertinib as second line therapy. After 3 moths of osimetinib treatment, she presented with dyspnea, high NT-proBNP and troponin I, and significantly decreased left ventricular ejection fraction (LVEF) at 28%. RV biopsy showed moderate cardiomyocyte hypertrophy without inflammatory cell infiltration. Case 2 was 52-year-old female with advanced NSCLC harboring L858R mutation. She was treated with osimertinib as first line therapy. After 2 weeks of osimertinib, screening echocardiography revealed a reduction of LVEF from 63% to 41% without cardiac symptom. RV biopsy showed mild cardiomyocyte hypertrophy with infiltration of a few inflammatory cells in interstinum. We further analyzed death case of NSCLC. Case 3 was 63-year-old female with advanced NSCLC harboring EGFR ex. 19 del. and T790M mutations. After 6 months of osimertinib, she suffered from severe respiratory failure and severely reduced LVEF at 27%. She died on the 44th day after admission. Pathological autopsy revealed mild to moderate cardiomyocyte hypertrophy without inflammatory cell infiltration in both ventricles. These pathological findings may indicate neither myocyte injury nor myocarditis was induced by osimertinib in myocardium.

Conclusion

Although additional data collection of advanced NSCLC patients will be important in understanding the pathophysiology of cardiac AEs with osimertinib, osimertinib-associated cardiotoxicity may result from functional inhibition of myocyte contractility by osimertinib without induction of cell death or inflammation.

Funding Acknowledgement

Type of funding source: None

Early detection of Niemann-pick disease type C with cataplexy and orexin levels: continuous observation with and without Miglustat

Study objectives

Niemann-Pick type C (NPC) is an autosomal recessive and congenital neurological disorder characterized by the accumulation of cholesterol and glycosphingolipids. Symptoms include hepatosplenomegaly, vertical supranuclear saccadic palsy, ataxia, dystonia, and dementia. Some cases frequently display narcolepsy-like symptoms, including cataplexy which was reported in 26% of all NPC patients and was more often recorded among late-infantile onset (50%) and juvenile onset (38%) patients. In this current study, we examined CSF orexin levels in the 10 patients of NPC with and without cataplexy, which supports previous findings.

Methods

Ten patients with NPC were included in the study (5 males and 5 females). NPC diagnosis was biochemically confirmed in all 10 patients, from which 8 patients with NPC1 gene were identified. We compared CSF orexin levels among NPC, narcoleptic and idiopathic hypersomnia patients.

Results

Six NPC patients with cataplexy had low or intermediate orexin levels. In 4 cases without cataplexy, their orexin levels were normal. In 5 cases with Miglustat treatment, their symptoms stabilized or improved. For cases without Miglustat treatment, their conditions worsened generally. The CSF orexin levels of NPC patients were significantly higher than those of patients with narcolepsy-cataplexy and lower than those of patients with idiopathic hypersomnia, which was considered as the control group with normal CSF orexin levels.

Discussion

Our study indicates that orexin level measurements can be an early alert of potential NPC. Low or intermediate orexin levels could further decrease due to reduction in the neuronal function in the orexin system, accelerating the patients’ NPC pathophysiology. However with Miglustat treatment, the orexin levels stabilized or improved, along with other general symptoms. Although the circuitry is unclear, this supports that orexin system is indeed involved in narcolepsy-cataplexy in NPC patients.

Conclusion

The NPC patients with cataplexy had low or intermediate orexin levels. In the cases without cataplexy, their orexin levels were normal. Our study suggests that orexin measurements can serve as an early alert for potential NPC; furthermore, they could be a marker of therapy monitoring during a treatment.

Catalytic specificity of the Lactobacillus plantarum cystathionine γ-lyase presumed by the crystallographic analysis

The reverse transsulfuration pathway, which is composed of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CGL), plays a role to synthesize L-cysteine using L-serine and the sulfur atom in L-methionine. A plant-derived lactic acid bacterium Lactobacillus plantarum SN35N has been previously found to harbor the gene cluster encoding the CBS- and CGL-like enzymes. In addition, it has been demonstrated that the L. plantarum CBS can synthesize cystathionine from O-acetyl-L-serine and L-homocysteine. The aim of this study is to characterize the enzymatic functions of the L. plantarum CGL. We have found that the enzyme has the high γ-lyase activity toward cystathionine to generate L-cysteine, together with the β-lyase activity toward L-cystine to generate L-cysteine persulfide. By the crystallographic analysis of the inactive CGL K194A mutant complexed with cystathionine, we have found the residues which recognize the distal amino and carboxyl groups of cystathionine or L-cystine. The PLP-bound substrates at the active site may take either the binding pose for the γ- or β-elimination reaction, with the former being the major reaction in the case of cystathionine.

Factors associated with possession of accurate knowledge regarding occupational health management among operations leaders of radiation decontamination workers in Fukushima, Japan: a cross-sectional study

OBJECTIVES

An operations leader (OL) takes an important role in occupational health management for radiation decontamination workers in Japan, and candidates for the position must participate in a training session to acquire the necessary knowledge as required by law. However, it has not been clarified whether the candidates for the OL position actually possess accurate knowledge regarding occupational health management for such work after the training session. We, therefore, aimed at examining the current occupational health management knowledge among the candidates and investigating factors related to the knowledge, with hypothesis that possession of accurate knowledge is associated with prior experience of having worked in radiation decontamination.

DESIGN

A cross-sectional study.

SETTING

The training sessions held by Fukushima Prefecture Labor Standard Associations in Fukushima, Japan, in 2017.

PARTICIPANTS

Eighty male candidates participated in the training sessions.

OUTCOME

The number/proportion of correct answers to the questions regarding occupational health management, such as those on working environment management, control of operations and health management.

RESULTS

The proportion of those who possessed accurate knowledge regarding working environment management, control of operations and health management was 68.8%, 55.0% and 51.2%, respectively. Experience of radiation decontamination work was associated with the possession of inaccurate knowledge regarding working environment management (OR 0.140 (95% CI 0.042 to 0.464)), and the uncertainty of future radiation decontamination work schedules in difficult-to-return zones was associated with the possession of accurate knowledge regarding health management (OR 4.344 (95% CI 1.509 to 12.50)).

CONCLUSIONS

Previous experience in radiation decontamination work may hinder the ability to acquire accurate information regarding working environment management among candidates for an OL position. To promote adequate occupational health management for radiation decontamination workers, it is required to establish an effective instructional method for the OL candidate training sessions with consideration of previous relevant experience.

Characterization of the SN35N Strain-Specific Exopolysaccharide Encoded in the Whole Circular Genome of a Plant-Derived Lactobacillus plantarum

Lactobacillus plantarum SN35N, which has been previously isolated from pear, secretes exopolysaccharide (EPS). The aim of the present study is to characterize the EPS chemically and to find the EPS-biosynthesizing gene cluster. The present study demonstrates that the strain produces an acidic EPS carrying phosphate residue, which is composed of glucose, galactose, and mannose at a molecular ratio of 15.0 : 5.7 : 1.0. We also show that acidic EPS strongly inhibits the catalytic activity of hyaluronidase (EC 3.2.1.35), promoting an inflammatory reaction. In the present study, we also determined the complete genome sequence of the SN35N strain, demonstrating that the genome is a circular DNA with 3267626 bp, and the number of predicted coding genes is 3146, with a GC content of 44.51%. In addition, the strain harbors four plasmids, designated pSN35N-1, -2, -3, and -4. Although four EPS-biosynthesizing genes, designated lpe1, lpe2, lpe3, and lpe4, are present in the SN35N chromosomal DNA, another EPS gene cluster, lpe5, is located in the pSN35N-3 plasmid, composed of 35425 bp. EPS low-producing mutants, which were obtained by treating SN35N cells with novobiocin, lost the lpe5 gene cluster in the plasmid-curing experiment, suggesting that the gene cluster for the biosynthesis of acidic EPS is present in the plasmid. The present study shows the chemical characterization of the acidic EPS and its inhibitory effect to the hyaluronidase.

Renoprotective effect of topiroxostat via antioxidant activity in puromycin aminonucleoside nephrosis rats

Topiroxostat is a novel inhibitor of xanthine oxidase, and is postulated to exert a renoprotective effect. Puromycin aminonucleoside nephrosis (PAN) is a rat model of minimal change nephrotic syndrome. In this study, we examined whether topiroxostat ameliorates the kidney injury in PAN rats that was induced by a single intraperitoneal injection of PA (100 mg/kg body weight). Rats were divided into four groups: control rats, PAN rats, control rats treated with topiroxostat (1.0 mg/kg/day), and PAN rats treated with topiroxostat. Topiroxostat significantly reduced the amount of uric acid in the kidney cortex, while serum UA concentration remained unaffected by this treatment. Urinary protein excretion decreased significantly on day 10 in PAN rats upon topiroxostat treatment. Podocyte injury in PAN rats, as indicated by the reduction in WT‐1‐positive cell numbers and podocin immunoreactivity and foot process effacement, was partially yet significantly alleviated with topiroxostat treatment. In the kidney cortex, the increase in oxidative stress markers such as nitrotyrosine and 8‐hydroxy‐2‐deoxyguanosine (8‐OHdG) and the enhanced expressions of xanthine oxidase and NADPH oxidase 4 (NOX4) in PAN rats were significantly ameliorated by topiroxostat. Using cultured podocytes NOX4 expression was upregulated by adding 12 mg/dL UA into the culture medium. These results suggest that topiroxostat ameliorates proteinuria and kidney injury in PAN rats by lowering oxidative stress and tissue UA concentration. The renoprotective effects of topiroxostat could be attributed to its potential to inhibit xanthine oxidase and NOX4 in concert with suppression of intracellular UA production.

Anharmonicity in a double hydrogen transfer reaction studied in a single porphycene molecule on a Cu(110) surface

Anharmonicity plays a crucial role in hydrogen transfer reactions in hydrogen-bonding systems, which leads to a peculiar spectral line shape of the hydrogen stretching mode as well as highly complex intra/intermolecular vibrational energy relaxation. Single-molecule study with a well-defined model is necessary to elucidate a fundamental mechanism. Recent low-temperature scanning tunnelling microscopy (STM) experiments revealed that the cis↔cis tautomerization in a single porphycene molecule on Cu(110) at 5 K can be induced by vibrational excitation via an inelastic electron tunnelling process and the N-H(D) stretching mode couples with the tautomerization coordinate [Kumagai et al. Phys. Rev. Lett. 2013, 111, 246101]. Here we discuss a pronounced anharmonicity of the N-H stretching mode observed in the STM action spectra and the conductance spectra. Density functional theory calculations find a strong intermode coupling of the N-H stretching with an in-plane bending mode within porphycene on Cu(110).

Time to Target Uric Acid to Retard Chronic Kidney Disease Progression

Uric acid (UA) remains a risk factor for the progression of chronic kidney disease (CKD). Most observational studies showed a slight elevation in the serum UA level and this independently predicts the incidence and development of CKD. The recent meta-analysis, however, did not reach the conclusion that urate-lowering therapy with allopurinol retards the progression of CKD. The target level of serum UA if treated is another issue of debate. Our recent analysis by propensity score analysis has shown that the serum UA should be targeted below 6.0 mg/dL to inhibit the progression towards end-stage renal disease. Underlying mechanisms whereby an increase in serum UA induces kidney injury have been elucidated in animal models. Hyperuricemic models can lead to systemic hypertension, arteriolosclerosis including afferent arteriolopathy as well as albuminuria probably due to the activation of oxidative stress. Discoveries of urate transporters have elucidated the novel mechanism of UA transport in the kidney and intestine. The intestinal ABCG2 may play a compensatory role in light of decreased renal clearance of UA in CKD model rats, the trigger of which is not a uremic toxin but serum UA itself. Insulin directly upregulates URAT1 and downregulates ABCG2 in the kidney tubules, suggesting a possible link between UA and metabolic syndrome. This review summarizes the recent knowledge on the causal effect of serum UA on the kidney injury.

Uric Acid in the Follow-Up Determines 30% Decline in Estimated GFR Over 2 Years: a Propensity Score Analysis

BACKGROUND/AIMS

Higher level of serum uric acid (SUA) predicts early entry to dialysis in chronic kidney disease (CKD) patients. However, a short-term effect of SUA remains to be elucidated using a novel surrogate endpoint.

METHODS

Japanese CKD stage 3 to 4 patients were retrospectively examined (n= 701). The follow-up level of SUA was estimated as time-averaged uric acid (TA-UA). A propensity score for 6.0, 6.5 or 7.0 mg/dL of TA-UA was respectively calculated using baseline 23 covariates. The time-to-event analysis was performed for 30% decline in estimated GFR over 2 years.

RESULTS

Incidence rates over 2 years were 90 of 440 in men and 36 of 261 in women (p = 0.03). Despite the negative result of baseline SUA, stratified Cox regression on the quintiles of the estimated propensity score showed that higher TA-UA of the three thresholds were all significant (crude HR 2.10 to 2.44) even after adjusting for the confounders. Kaplan-Meier analysis after propensity score matching likewise showed worse survival in the patients with the higher TA-UA (HR 3.11 to 4.26).

CONCLUSION

Higher SUA increases likelihood of reaching a surrogate endpoint over 2 years. Early intervention for SUA less than 6.0 mg/dL is recommended for slowing CKD progression.

Asunaprevir and daclatasvir in hemodialysis patients with chronic hepatitis C virus genotype 1b infection

Background and Aim

Patients requiring hemodialysis show high morbidity with hepatitis C virus (HCV) infection, but there are difficulties associated with interferon‐based therapies. Asunaprevir and daclatasvir could help patients with HCV genotype 1b because the drugs have a nonrenal metabolism and show good viral eradication. We evaluated the efficacy and safety of combined asunaprevir and daclatasvir therapy.

Methods

This was a multicenter prospective trial of patients with chronic hepatitis or compensated cirrhosis from HCV genotype 1b who had end‐stage renal disease requiring chronic hemodialysis. Asunaprevir and daclatasvir were administered orally (100 mg twice daily and 60 mg once daily, respectively) for 24 weeks. The primary end‐point was the proportion of patients achieving sustained virological response 12, defined as HCV RNA <15 IU/mL undetectable at 12 weeks after completion of asunaprevir and daclatasvir treatment.

Results

Between December 2014 and December 2015, 23 dialysis patients were enrolled, and 22 patients completed the protocol therapy. Sustained virological response 12 rates were 91.3% (95% confidence interval: 72.0–98.9) in the intention‐to‐treat and 95.5% (95% confidence interval: 77.2–99.9) in the per‐protocol populations. Serum aminotransferase significantly decreased after initiation of asunaprevir and daclatasvir (P < 0.01), although the level was low at baseline. Asunaprevir and daclatasvir were well tolerated; however, one patient could not continue because of infective endocarditis and cerebral infarction.

Conclusions

Asunaprevir and daclatasvir could help patients with chronic hepatitis C receiving hemodialysis. Close collaboration with dialysis physicians is important when treating these patients because hemodialysis carries life‐threatening risks.

Uric acid metabolism of kidney and intestine in a rat model of chronic kidney disease

Uric acid (UA) is a potential risk factor of the progression of chronic kidney disease (CKD). Recently, we reported that intestinal UA excretion might be enhanced via upregulation of the ATP-binding cassette transporter G2 (Abcg2) in a 5/6 nephrectomy (Nx) rat model. In the present study, we examined the mRNA and protein expressions of UA transporters, URAT1, GLUT9/URATv1, ABCG2 and NPT4 in the kidney and ileum in the same rat model. Additionally, we investigated the Abcg2 mRNA expression of ileum in hyperuricemic rat model by orally administering oxonic acid. Male Wistar rats were randomly assigned to three groups consisting of Nx group, oxonic acid-treated (Ox) group and sham-operated control group, and sacrificed at 8 weeks. Creatinine and UA were measured and the mRNA expressions of UA transporters in the kidney and intestine were evaluated by a real time PCR. UA transporters in the kidney sections were also examined by immunohistochemistry. Serum creatinine elevated in the Nx group whereas serum UA increased in the Ox group. Both the mRNA expression and the immunohistochemistry of the UA transporters were decreased in the Nx group, suggesting a marginal role in UA elevation in decreased kidney function. In contrast, the mRNA expression of Abcg2 in the ileum significantly increased in the Ox group. These results suggest that the upregulation of Abcg2 mRNA in the ileum triggered by an elevation of serum UA may play a compensatory role in increasing intestinal UA excretion.

Spectroscopic and microscopic investigations of tautomerization in porphycenes: condensed phases, supersonic jets, and single molecule studies

Tautomerization of porphycene, coherent in supersonic jets and a rate process in solutions, can be controlled for single molecules on surfaces.

Local electronic structure, work function, and line defect dynamics of ultrathin epitaxial ZnO layers on a Ag(1 1 1) surface

Using combined low-temperature scanning tunneling microscopy and Kelvin probe force microscopy we studied the local electronic structure and work function change of the (0 0 0 1)-oriented epitaxial ZnO layers on a Ag(1 1 1) substrate. Scanning tunneling spectroscopy (STS) revealed that the conduction band minimum monotonically downshifts as the number of the ZnO layers increases up to 4 monolayers (ML). However, it was found by field emission resonance (FER) spectroscopy that the local work function of Ag(1 1 1) slightly decreases for 2 ML thick ZnO but it dramatically changes and drops by about 1.2 eV between 2 and 3 ML, suggesting a structural transformation of the ZnO layer. The spatial variation of the conduction band minimum and the local work function change were visualized at the nanometer scale by mapping the STS and FER intensities. Furthermore, we found that the ZnO layers contained line defects with a few tens of nm long, which can be removed by the injection of a tunneling electron into the conduction band.

Novel double step approach for optical sensing via microsphere WGM resonance

The use of resonant whispering gallery modes (WGMs) for sensing exhibits various drawbacks and critical points related to the microsphere and tapered optical fiber fabrication tolerance. The uncertainty on the fiber taper and microsphere geometry or the gap between the microsphere and the fiber taper can complicate or limit the actual use of these devices for sensing, requiring peculiar calibration of the WGM based sensing set-up. An alternative double-step approach is proposed in this paper. In particular, the geometrical parameters of the set-up are recovered preliminarily and then the rare earth parameters are recovered via simple transmittance/gain measurements. The method is based on a refined electromagnetic model of the device suitably integrated with a particle swarm optimization (PSO) approach. The percent errors made on the up-conversion coefficients C_up and C₃ are extremely low, being 0.75%, 0.05%, respectively. The procedure is very robust. It can be applied more in general, allowing the sensing of other physical parameters via simple transmittance measurements instead of wavelength shift ones, in both microsphere and microbubble based set-up.

Characterization and Mutational Analysis of a Two-Polypeptide Bacteriocin Produced by Citrus Iyo-Derived Lactobacillus brevis 174A

In the present study, we isolated a lactic acid bacterium (LAB) from a citrus iyo fruit and identified it as Lactobacillus brevis. This plant-derived LAB strain, designated 174A, produces bacteriocin consisting of two polypeptides designated brevicin 174A-β and 174A-γ. Although each polypeptide itself displays antibacterial activity, the ability is enhanced 100 fold by mixing both polypeptides at a 1 : 1 ratio. Significantly, brevicin 174A inhibits even the growth of several pathogenic bacteria that are more resistant to a lantibiotic bacteriocin, nisin A, which is commonly utilized as a preservative added to foodstuffs. Structural analysis of the 174A bacteriocin using a program that predicts secondary structure suggests that both component polypeptides have a positively charged N-terminal region, as well as two cysteine residues in both the N- and C-terminals. Judging from a mutational analysis of the antibacterial polypeptides, these unique amino acid sequences of 174A-β might be important for the expression of the synergistic activity that occurs in the presence of the two polypeptides combined.

Cytokine-related and sodium channel polymorphism as candidate predisposing factors for childhood encephalopathy FIRES/AERRPS

Febrile infection-related epilepsy syndrome (FIRES), or acute encephalitis with refractory, repetitive partial seizures (AERRPS), is an epileptic encephalopathy beginning with fever-mediated seizures. The etiology remains unclear. To elucidate the genetic background of FIRES/AERRPS (hereafter FIRES), we recruited 19 Japanese patients, genotyped polymorphisms of the IL1B, IL6, IL10, TNFA, IL1RN, SCN1A and SCN2A genes, and compared their frequency between the patients and controls. For IL1RN, the frequency of a variable number of tandem repeat (VNTR) allele, RN2, was significantly higher in the patients than in controls (p=0.0067), and A allele at rs4251981 in 5' upstream of IL1RN with borderline significance (p=0.015). Haplotype containing RN2 was associated with an increased risk of FIRES (OR 3.88, 95%CI 1.40-10.8, p=0.0057). For SCN1A, no polymorphisms showed a significant association, whereas a missense mutation, R1575C, was found in two patients. For SCN2A, the minor allele frequency of G allele at rs1864885 was higher in patients with borderline significance (p=0.011). We demonstrated the association of IL1RN haplotype containing RN2 with FIRES, and showed a possible association of IL1RN rs4251981 G>A and SCN2A rs1864885 A>G, in Japanese patients. These preliminary findings suggest the involvement of multiple genetic factors in FIRES, which needs to be confirmed by future studies in a larger number of FIRES cases.

Time to target uric acid to retard CKD progression

Uric acid (UA) remains a possible risk factor of chronic kidney disease (CKD) but its potential role should be elucidated given a fact that multidisciplinary treatments assure a sole strategy to inhibit the progression to end-stage renal disease (ESRD). In clinical setting, most observational studies showed that elevation of serum uric acid (SUA) independently predicts the incidence and the development of CKD. The meta-analysis showed that SUA-lowering therapy with allopurinol may retard the progression of CKD but did not reach conclusive results due to small-sized studies. Larger scale, randomized placebo-controlled trials to assess SUA-lowering therapy are needed. Our recent analysis by propensity score methods has shown that the threshold of SUA should be less than 6.5 mg/dL to abrogate ESRD. In animal models an increase in SUA by the administration of oxonic acid, uricase inhibitor, or nephrectomy can induce glomerular hypertension, arteriolosclerosis including afferent arteriolopathy and tubulointerstitial fibrosis. The ever-growing discoveries of urate transporters prompt us to learn UA metabolism in the kidney and intestine. One example is that the intestinal ABCG2 may play a compensatory role at face of decreased renal clearance of UA in nephrectomized rats, the trigger of which is not a uremic toxin but SUA itself. This review will summarize the recent knowledge on the relationship between SUA and the kidney and try to draw a conclusion when and how to treat asymptomatic hyperuricemia accompanied by CKD. Finally we will address a future perspective on UA study including a Mendelian randomization approach.