bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Radix isatidis polysaccharide on alleviating insulin resistance in type 2 diabetes mellitus cells and rats
Authors: Li Ji-ping , Yuan Ye , Zhang Wen-you , Jiang Zhen , Hu Tian-jiao , Feng Yi-ting , Liu Mo-xiang
Published: October 2018

Objectives

The objective of this paper was to explore the effects of Radix isatidis polysaccharide (RIP) extracted from Radix isatis on alleviating insulin resistance.

Methods

The insulin resistance models of 3T3-L1 preadipocytes and type 2 diabetic rats were established to evaluate the insulin resistance activity of RIP.

Key findings

Radix isatidis polysaccharide within the concentration range of 25–100 μg/ml could reduce cell supernatant glucose and TNF-α levels (P < 0.01) and increase the expression of PI-3K P85, Glut4, IRS-1 and Akt protein in symptoms of IR 3T3-L1 preadipocytes. In the meantime, RIP contributed to relieve the weight loss of diabetic rats whose liver weight and liver index were decreased due to the effects of RIP. Experiments in rats also showed that RIP had capacity in reduced serum TC, TG, LDL-C, FFA, FBG, FINS, MDA, ALT, AST activities and increased serum HDL-C, SOD, ISI (P < 0.05 or 0.01). In addition, the oral glucose tolerance in rats was improved (P < 0.05) and liver damage was restored due to RIP.

Conclusions

Radix isatidis polysaccharide significantly alleviates insulin resistance in 3T3-L1 preadipocytes and type 2 diabetic rats. These beneficial effects of RIP may associate with their roles in improving the glucose metabolism, lipid metabolism and oxidative stress.
Metabolic analysis of the melatonin biosynthesis pathway using chemical labeling coupled with liquid chromatography‐mass spectrometry
Authors: Ye Tiantian , Yin Xiaoming , Yu Lei , Zheng Shu‐Jian , Cai Wen‐Jing , Wu Yan , Feng Yu‐Qi
Published: October 2018

Characterization of the melatonin (MLT) biosynthesis pathway in plants is still limited. Additionally, a metabolomic analysis of MLT biosynthesis in plants is still a challenge due to analyte structural and chemical diversity, low analyte abundances, and plant matrix complexities. Herein, a sensitive liquid chromatography‐mass spectrometry (LC‐MS) method enabling the simultaneous determination of seven plant MLT biosynthetic metabolites was developed. In the proposed strategy, the targeted metabolites, which included tryptophan (Trp), tryptamine (TAM), 5‐hydroxytryptophan (5HTP), serotonin (5HT), N‐acetylserotonin (NAS), 5‐methoxytryptamine (5MT), and MLT, were purified from plant extracts using a one‐step dispersive solid‐phase extraction (DSPE). The samples were then chemically labeled with dansyl chloride (DNS‐Cl), followed by analysis using LC‐MS. The limit of detection (LOD) values ranged from 0.03 to 1.36 pg/mL and presented a 22‐ to 469‐fold decrease when compared to the unlabeled metabolites. Due to the high sensitivity of the proposed method, the consumption of plant materials was reduced to 10 mg FW. Ultimately, the established method was utilized to examine the distributions of MLT and its intermediates in rice shoots and roots with or without cadmium (Cd) stress. The results suggested that under normal condition, MLT may also be generated via a Trp/TAM/5HT/5MT/MLT path (Pathway II) in addition to the previously reported Trp/TAM/5HT/NAS/MLT path (Pathway I), although Pathway I was shown to be dominant. During Cd stress, MLT was also shown to be produced through these two pathways, with Pathway II shown to be dominant in rice shoots and roots.
Characterization and comparison of neutrophil extracellular traps in gingival samples of periodontitis and gingivitis: A pilot study
Authors: Magán‐Fernández Antonio , O'Valle Francisco , Abadía‐Molina Francisco , Muñoz Ricardo , Puga‐Guil Patricia , Mesa Francisco
Published: October 2018

Background and Objective

Neutrophil extracellular traps (NETs) are a recently discovered antimicrobial mechanism used by neutrophils that have been proposed as an intervention in the pathogenesis of periodontitis. The objective of our study was to characterize the expression of NETs in gingival tissues with periodontitis and controls and to compare the expression of these traps in gingival tissue samples of patients with gingivitis and periodontitis.

Material and Methods

An observational cross‐sectional study was conducted on patients with periodontitis, gingivitis, and controls that needed tooth extraction. Gingival tissue biopsies were gathered after clinical examination and tooth extraction. Electron microscopy and immunofluorescence were performed to characterize NETs, comparing periodontitis and control patients. Immunohistochemical analysis was performed to quantify neutrophil extracellular trap expression through extracellular citrullinated histone H3 and myeloperoxidase in biopsies from patients with gingivitis and periodontitis.

Results

Thirteen biopsies were gathered from 13 patients: five gingivitis, six periodontitis, and two controls. Electron microscopy and immunofluorescence imaging showed greater expression of neutrophils present in periodontal inflamed tissue compared with controls. Release of nuclear content to the extracellular space was observed, compatible with the formation of NETs. The expression of citrullinated histone H3 was higher in gingivitis samples than periodontitis samples (P = 0.0106). Myeloperoxidase expression was higher in periodontitis than gingivitis, but without achieving statistical significance.

Conclusion

Neutrophil extracellular traps were found in tissue samples of periodontitis as extracellular components of chromatin, along with neutrophil enzymes, that were not present in healthy controls. The comparison of NETs expression in periodontitis and gingivitis showed higher expression in gingivitis, associating them to acute phases of the periodontal inflammatory process.
Retrospective Orientation to Learning Activities and Achievements as a Resource in Classroom Interaction
Authors: JAKONEN TEPPO
Published: October 2018

This article explores the temporal nature of language learning in classroom settings through the lens of Conversation Analysis (CA) by drawing on video‐recorded interactions from Content and Language Integrated (CLIL) classrooms. It outlines some methodological challenges that the task of documenting language learning in and as observable social interaction poses for CA studies of second language (L2) learning and proposes that learning has typically been described as either a situated activity (in cross‐sectional studies) or a series of intermediate achievements (in longitudinal studies). The empirical analysis focuses on interactional instances in which students observably invoke and describe their earlier learning activities or achievements as part of some ongoing classroom activity, either in whole‐class or peer interaction. It is argued that such instances of a retrospective orientation to learning offer empirical materials for examining learning trajectories from a participant's perspective, how connections between moments and social domains separated by time and space are forged, and how resources are accumulated, recalibrated, and put to use. The focal interactions also raise conceptual implications for the ways in which learning is both situated and transferable, as well as methodological implications for how retrospection can best be rendered analytically accessible by way of a CA approach.
Invited Review: From nose to gut – the role of the microbiome in neurological disease
Authors: Bell J. S. , Spencer J. I. , Yates R. L. , Yee S. A. , Jacobs B. M. , DeLuca G. C.
Published: October 2018

Inflammation and neurodegeneration are key features of many chronic neurological diseases, yet the causative mechanisms underlying these processes are poorly understood. There has been mounting interest in the role of the human microbiome in modulating the inflammatory milieu of the central nervous system (CNS) in health and disease. To date, most research has focussed on a gut‐brain axis, with other mucosal surfaces being relatively neglected. We herein take the novel approach of comprehensively reviewing the roles of the microbiome across several key mucosal interfaces – the nose, mouth, lung and gut – in health and in Parkinson's disease (PD), Alzheimer's disease (AD) and multiple sclerosis (MS). This review systematically appraises the anatomical and microbiological landscape of each mucosal surface in health and disease before considering relevant mechanisms that may influence the initiation and progression of PD, AD and MS. The cumulative effects of dysbiosis from the nose to the gut may contribute significantly to neurological disease through a wide variety of mechanisms, including direct translocation of bacteria and their products, and modulation of systemic or CNS‐specific immunity. This remains an understudied and exciting area for future research and may lead to the development of therapeutic targets for chronic neurological disease.
Perspectives on acute kidney injury strategy: Hong Kong
Authors: Szeto Cheuk‐Chun
Published: October 2018

Acute kidney injury is a common condition in hospitalized patients and a strong predictor of short‐term morbidity and mortality. In this article, local epidemiological data on the prevalence and outcome of acute kidney injury amongst hospitalized patient in a tertiary referral center were discussed. The latest practice guidelines endorsed by the Hong Kong College of Physicians will be discussed, with emphasis on local practical issues and problems of guideline implementation.
Glomerular mesangial cell and podocyte injuries in diabetic nephropathy
Authors: Tung Chun‐Wu , Hsu Yung‐Chien , Shih Ya‐Hsueh , Chang Pey‐Jium , Lin Chun‐Liang
Published: October 2018

Diabetic nephropathy is one of the leading causes of end‐stage renal disease and creates heavy healthcare burdens globally. Dysfunction of mesangial cells and podocytes contributes to diabetic nephropathy. Dysregulation of signaling involved in renal development and regeneration may cause diabetic kidney damages. Growing evidences suggest the importance of dysregulated dickkopf‐1 (DKK1)/Wnt/ β‐catenin signaling pathways in the pathogenesis of diabetic glomerular injuries. The inhibition of Wnt signaling in injured mesangial cells is likely attributed to the high glucose‐induced Ras/Rac1 dependent superoxide formation. When DKK1, the cellular inhibitor of Wnt signaling, binds to the Kremen‐2 receptor, depositions of extracellular matrix increase in the mesangium of diabetic kidneys. Additionally, reactivation of Notch‐1 signaling has been implicated in podocytopathy during diabetic proteinuria development. Knocking down Notch‐1 alleviates vascular endothelial growth factor (VEGF) expression, nephrin repression and proteinuria in diabetic kidneys. It is also found that epigenetic modulations by histone deacetylase 4 (HDAC4) and miR‐29a could lead to diabetic nephropathy. High glucose increases the expression of HDAC4, which causes deacetylation with subsequent ubiquitination of nephrin. Overexpression of miR‐29a in diabetic transgenic mice would decrease the expression of HDAC4 and stabilize nephrin. Surprisingly, reprogramming or reactivation of signaling involved in renal development or regeneration often brings about diabetic glomerular sclerosis in mesangial cells and podocytes. Better knowledge about modifications of embryonic stem cell signaling will have a chance to implement strategically focused pharmacological research programs aiming to the development of new drugs for diabetic kidney injuries.
Role of Krüppel‐like factor‐2 in kidney disease
Authors: Zhong Fang , Lee Kyung , He John C
Published: October 2018

Krüppel‐like factor‐2 (KLF2) is a transcription factor that plays a major role in the regulation of endothelial cell function. KLF2 protects against endothelial cell injury through its anti‐inflammatory, anti‐thrombotic and anti‐angiogenic effects to maintain the normal vascular integrity. Our recent data indicate that KLF2 is down‐regulated in glomerular endothelial cells of patients with diabetic kidney disease and that endothelial cell‐specific reduction in KLF2 expression in experimental model of diabetic kidney disease exacerbates glomerular endothelial cell injury and accelerates the disease progression. KLF2 is a key transcriptional regulator of endothelial nitric oxide synthase, and its renoprotective function may be mediated through the increased endothelial nitric oxide synthase expression. As KLF2 expression is stimulated by shear stress, we also investigated the role of KLF2 in the nephrectomy mouse model, in which the endothelial KLF2 expression would be increased through glomerular hyperfiltration in the remnant kidney. Reduction of endothelial KLF2 led to increased glomerular endothelial cell injury and progressive kidney disease in uninephrectomized mice. Interestingly, KLF2 expression is also reduced in nephrectomy patients with progressive kidney disease as compared to those with the non‐progressive disease. Together, these studies indicate a critical role of KLF2 in maintaining normal glomerular endothelial cell function and that deficiency of KLF2 leads to more progressive kidney disease.
Advanced therapeutics in focal and segmental glomerulosclerosis
Authors: Liu Yunzi , Shi Yifan , Ren Rong , Xie Jingyuan , Wang Weiming , Chen Nan
Published: October 2018

Focal segmental glomerulosclerosis (FSGS) is a glomerulonephritis with podocyte injury. The renal prognosis of FSGS is relative poor. The overall remission rate of the FSGS patients with nephrotic syndrome to immunosuppressive treatments was reported as 47–66%, highlighting its therapeutic challenge—lacking in sufficient evidence‐based interventions. In first‐line treatment of nephrotic syndrome, daily oral prednisolone is a commonly used drug, whereas optimal treatment strategies, like indications and duration, remain controversial. Calcineurin inhibitor and cyclophosphamide are recommended in steroid‐dependent/steroid‐resistant patients. However, the high unmet need in effective immunosuppressive treatments calls for the development of new therapy methods. Rituximab, a monoclonal antibody targeting CD20 B‐cells, could increase the complete or partial remission rate, and decrease the relapse rate based on several previous studies on FSGS. In addition, the using of rituximab could potentially help the FSGS patients to stop the concomitant therapy include steroid and immunosuppressive agents. Other treatment options like adalimumab or abatacept also showed potential therapeutic effect, but still required larger Randomized Controlled Trial study to determine its efficiency and safety. Besides, expanding understanding of the genetic basis of FSGS is necessary to investigate new therapeutic agents. With the unsatisfied patients’ outcome under the current treatments, innovation should be encouraged on the treatment strategy based on Kidney Disease: Improving Global Outcomes guideline and international collaborations are required for the potential novel immunosuppressive or immunomodulatory therapies.
Chronic kidney disease epidemic: How do we deal with it?
Authors: Ng Jack K‐C , Li Philip K‐T
Published: October 2018

Chronic kidney disease (CKD) is a leading cause of mortality and morbidity around the world. The prevalence of CKD increases steadily over the past decade in parallel to the rapid expansion of diabetic population. Apart from increased mortality, CKD also has significant impact on quality of life and the economy. The approach to deal with the global CKD epidemic is multifaceted. Early detection by screening high‐risk individuals such as those with hypertension and diabetes is important and cost‐effective. However, low CKD awareness in many countries may impose barriers to early intervention. Hence raising CKD awareness among public and policy makers should be encouraged. In addition, the use of peritoneal dialysis, a less costly and home‐based dialysis modality compared with in‐center haemodialysis, should be promoted to maximize access to dialysis with limited resources. Finally, ongoing research and clinical trials through international collaborations could provide further insight into the pathophysiology of CKD progression, and establish the foundation for development of specific therapeutic agents to retard progression to end stage renal failure.
New insights into the role and mechanism of Wnt/β‐catenin signalling in kidney fibrosis
Authors: Zuo Yangyang , Liu Youhua
Published: October 2018

Wnt/β‐catenin is an evolutionarily conserved, developmental signalling pathway that regulates embryogenesis, injury repair and pathogenesis of human diseases. Dysregulated activation of Wnt/β‐catenin is associated with the development and progression of renal fibrotic lesions after injury. Wnt are induced and β‐catenin is activated in various models of experimental chronic kidney disease (CKD) and in human nephropathies. Recent findings indicate that pro(renin) receptor is an amplifier of Wnt/β‐catenin by acting as a downstream target and an obligatory component for its signal transduction. Genetic blockade of Wnt secretion in a cell type‐specific manner uncovers renal tubular epithelium as the major source of Wnt ligands in CKD. Wnt/β‐catenin controls the expression of a wide variety of downstream mediators implicated in kidney fibrosis, such as fibronectin, Snail1, matrix metalloproteinase‐7, hepatocyte growth factor and various components of the renin‐angiotensin system. Targeted inhibition of Wnt/β‐catenin is able to ameliorate kidney fibrotic lesions in pre‐clinical settings. In this review, we summarize recent advances in our understanding of the regulation, signal transduction, role and mechanisms of Wnt/β‐catenin signalling in the pathogenesis of kidney fibrosis. We also discuss the therapeutic potential of targeting this pathway for the treatment of fibrotic CKD.
Comparison of skin autofluorescence, a marker of tissue advanced glycation end‐products in peritoneal dialysis patients using standard and biocompatible glucose containing peritoneal dialysates
Authors: Vongsanim Surachet , Fan Stanley , Davenport Andrew
Published: October 2018

Background

Heat sterilization of peritoneal dialysis (PD) dialysates leads to the generation of advanced glycation products (AGE), which can then deposit in the skin and be measured by skin autofluorescence (SAF). Newer biocompatible dual chamber dialysates contain less AGE. We wished to determine whether the use of these newer dialysates resulted in lower SAF.

Methods

Skin autofluorescence was measured using the AGE reader, which directs ultraviolet light, intensity range 300–420 nm (peak 370 nm) in patients established on PD for >3 months using glucose containing dialysates.

Results

We screened 196 consecutive patients, and measured SAF in 150; 86 (57.3%) male, median age 62 (53–71) years, median duration of PD treatment 17 (8.6–34.3) months. The median SAF was 3.48 (2.92–4.26) AU.

The median SAF in the 57 (38%) patients prescribed biocompatible dual chamber bag dialysates was 3.39 (2.69–3.98) versus 3.5 (3.05–4.54) for those using standard dialysates (P = 0.044). Although prescription of biocompatible fluids was associated with SAF on univariate analysis, but not on multivariable testing, SAF was independently associated with Stoke–Davies co‐morbidity grade (β 0.045, 95% confidence limits (CL) 0.015–0.075, P = 0.002), log duration of PD therapy (β 0.051, CL 0.001–0.101, P = 0.045), white ethnicity (β 0.066, CL 0.028–0.104, P = 0.001), and negatively with serum albumin (β −0.006, CL −0.008 to −0.004, P = 0.014).

Conclusion

Although SAF was lower in PD patients prescribed biocompatible dual chamber dialysates, on multivariable testing these dialysates were not independently associated with SAF. Other factors than PD fluid AGE content appear more important in determining SAF.
Transcutaneous electrical acustimulation synchronized with inspiration improves gastric accommodation impaired by cold stress in healthy subjects
Authors: Ma Gang , Hu Pingping , Zhang Bo , Xu Feng , Yin Jieyun , Yang Xiaozhong , Lin Lin , Chen Jiande D. Z.
Published: October 2018

Background

The aim of this study was to investigate whether transcutaneous electrical acustimulation (TEA) synchronized with inspiration (STEA), a method known to enhance vagal activity, was more effective than TEA in improving cold stress‐induced impairment in gastric accommodation (GA) and dyspeptic symptoms in healthy subjects.

Methods

Each of fifteen healthy subjects was studied in five randomized sessions: control (warm nutrient liquid), cold nutrient liquid (CNL), CNL+sham‐TEA, CNL+TEA, and CNL+STEA. The subjects were requested to drink Ensure until reaching maximum satiety. STEA was performed using the same parameters as TEA but asking the subjects to breathe in when they sensed each stimulation train. The electrogastrogram (EGG) and electrocardiogram (ECG) were recorded to assess gastric slow waves (GSW) and autonomic functions, respectively.

Key Results

GA was reduced with the CNL in comparison with the warm drink but increased with TEA and STEA; STEA was more potent than TEA in improving GA; STEA was more potent in improving GSW than TEA; STEA significantly increased vagal activity and decreased sympathetic activity compared with TEA.

Conclusions and Inferences

TEA synchronized with inspiration is more potent than TEA in improving cold stress‐induced impairment in GA and GSW and dyspeptic symptoms and might be a novel noninvasive therapy for treating stress‐induced dysmotility and dyspeptic symptoms.
A retrospective study of the impact of supraglottic airway devices on the appearance of neck masses in children undergoing serial magnetic resonance imaging
Authors: Simpao Allan F. , Obsekov Vladislav , Gálvez Jorge A. , Isserman Rebecca S. , Rehman Mohamed A. , Schwartz Erin S.
Published: October 2018

Background

General anesthesia and sedation are used routinely for magnetic resonance imaging (MRI) studies in children to optimize image quality. Airway devices such as supraglottic airways (SGAs) can alter the appearance of cervical soft tissue regions on an MRI and increase the risk of misdiagnosis. This phenomenon has not been well described in vivo.

Aims

We conducted this retrospective study to determine how often SGAs affected the appearance of neck masses in children who received multiple anesthetics for MRIs with and without an SGA.

Methods

We retrieved data on children 17 years old and younger who had multiple MRIs between January 2005 and January 2015. Inclusion criteria were patients with neck masses who had a SGA for at least one MRI and either a natural airway or endotracheal tube (ETT) for another MRI. We reviewed MRI images and imaging reports to determine if SGAs affected the appearance of neck masses.

Results

Twelve of the 921 patients who received anesthesia for neck MRIs during the study period met the inclusion criteria. SGAs affected the appearance of the neck mass in 11 of the 12 patients.

Conclusions

Supraglottic airways can significantly alter the appearance of neck masses in children undergoing MRIs and affect radiologists’ ability to assess those masses. Communication with the radiologist prior to the induction of anesthesia is crucial when using supraglottic devices in this patient population. It may be more prudent to use a different airway device and/or anesthetic technique when MRIs of these neck masses are undertaken.
Evolutionary Debunking Arguments Meet Evolutionary Science
Authors: Levy Arnon , Levy Yair
Published: October 2018

Evolutionary debunking arguments appeal to selective etiologies of human morality in an attempt to undermine moral realism. But is morality actually the product of evolution by natural selection? Although debunking arguments have attracted considerable attention in recent years, little of it has been devoted to whether the underlying evolutionary assumptions are credible. In this paper, we take a closer look at the evolutionary hypotheses put forward by two leading debunkers, namely Sharon Street and Richard Joyce. We raise a battery of considerations, both empirical and theoretical, that combine to cast doubt on the plausibility of both hypotheses. We also suggest that it is unlikely that there is in the vicinity a plausible alternative hypothesis suitable for the debunker's cause.
Suicide Exposure in Law Enforcement Officers
Authors: Cerel Julie , Jones Blake , Brown Melissa , Weisenhorn David A. , Patel Kyra
Published: October 2018

Objective

To examine occupational and personal suicide exposure among Law Enforcement Officers (LEOs) and related mental health outcomes.

Methods

Law Enforcement Officers (N = 813) completed an online survey about their suicide exposure, whether scenes stayed with them, and current symptoms of depression, anxiety, PTSD, and suicidal ideation.

Results

Almost all participants (95%) had responded to at least one suicide scene with an average of 30.90 (SD = 57.28) career suicide scenes and 2.17 in the last year (SD = 4.11). One in five (22%) reported a scene that they cannot shake or have nightmares about, and 42.5% reported one scene that stayed with them. Almost three fourths (73.4%) knew someone personally who had died by suicide. There was a significant association between high levels of occupational exposure to suicide and behavioral health consequences including PTSD, persistent thoughts of a suicide scene, and the inability to shake a scene. The inability to shake a scene and having a scene stick with them was associated with increased symptoms of depression, anxiety, PTSD, and suicidal ideation.

Conclusions

LEOs experience a tremendous amount of exposure to suicide scenes and also have personal exposure. There is a need for training to mitigate the effect of these multiple traumas on their mental health.
Multilingualism and theories of second language acquisition in Africa
Authors: Bokamba Eyamba G.
Published: October 2018

This article analyzes Multiple Language Acquisition (MLA) and functioning in Africa as a case study of multilingualism. It interrogates central aspects of the dominant L2 acquisition (SLA) paradigm that is predicated primarily on mother tongue (L1) monolingualism, and presents data that document high levels of individual multilingualism (3–8 languages), and the achievement of native to near‐native proficiency in three to five of them. The article draws upon these findings to critique key tenets of SLA theories, focusing on the ‘Critical Period Hypothesis’ (CPH) and its extension to the acquisition of additional languages beyond L1; its use as an explanatory tool for the development of the so‐called ‘interlanguage’ grammars by learners; and their failure to achieve the ‘ultimate attainment’ in L2, L3, and Ln. It is argued that CPH is inapplicable to L2, L3, and Ln, because it fails to predict native‐like proficiency beyond L1. It concludes by offering an explanation for the achievement of ‘native‐like’ proficiency in several languages by post‐pubescent Africans.
Preassembled GPCR signaling complexes mediate distinct cellular responses to ultralow ligand concentrations
Authors: Civciristov Srgjan , Ellisdon Andrew M. , Suderman Ryan , Pon Cindy K. , Evans Bronwyn A. , Kleifeld Oded , Charlton Steven J. , Hlavacek William S. , Canals Meritxell , Halls Michelle L.
Published: October 2018

Ultralow ligand concentrations stimulate GPCR signaling that is distinct from that elicited by high concentrations of ligand.
Molecular Basis of the Leishmanicidal Activity of the Antidepressant Sertraline as a Drug Repurposing Candidate
Authors: Lima Marta L. , Abengózar María A. , Nácher-Vázquez Montserrat , Martínez-Alcázar María P. , Barbas Coral , Tempone Andre G. , López-Gonzálvez Ángeles , Rivas Luis
Published: October 2018

Drug repurposing affords the implementation of new treatments at a moderate cost and under a faster time-scale. Most of the clinical drugs against
Leishmania
share this origin.
Antifungal azoxybacilin exhibits activity by inhibiting gene expression of sulfite reductase
Authors: Aoki Y , Yamamoto M , Hosseini-Mazinani S M , Koshikawa N , Sugimoto K , Arisawa M
Published: October 2018

Azoxybacilin, produced by Bacillus cereus, has a broad spectrum of antifungal activity in methionine-free medium and has been suggested to inhibit sulfite fixation. We have further investigated the mode of action by which azoxybacilin kills fungi. The compound inhibited the incorporation of [35S] sulfate into acid-insoluble fractions of Saccharomyces cerevisiae under conditions in which virtually no inhibition was observed for DNA, RNA, or protein synthesis. It did not interfere with the activity of the enzymes for sulfate assimilation but clearly inhibited the induction of those enzymes when S. cerevisiae cells were transferred from rich medium to a synthetic methionine-free medium. Particularly strong inhibition was observed in the induction of sulfite reductase. Northern (RNA) analysis revealed that azoxybacilin decreased the level of mRNA of genes for sulfate assimilation, including MET10 for sulfite reductase and MET4, the transactivator of MET10 and other sulfate assimilation genes. When activities of azoxybacilin were compared for mRNA and enzyme syntheses from MET10, the concentration required for inhibition of transcription of the gene was about 10 times higher (50% inhibitory concentration = 30 micrograms/ml) than that required for inhibition of induction of enzyme synthesis (50% inhibitory concentration = 3 micrograms/ml). The data suggest that azoxybacilin acts on at least two steps in the expression of sulfite reductase; the transcriptional activation of MET4 and a posttranscriptional regulation in MET10 expression. We conclude that azoxybacilin exhibits antifungal activity by interfering with the regulation of expression of sulfite reductase activity.
In vitro selection of one-step mutants of Streptococcus pneumoniae resistant to different oral beta-lactam antibiotics is associated with alterations of PBP2x
Authors: Sifaoui F , Kitzis M D , Gutmann L
Published: October 2018

Many oral penicillins and cephalosporins are used to treat clinical infections caused by Streptococcus pneumoniae. Therefore, using different beta-lactams as selectors, we estimated the frequencies of one-step mutations leading to resistance. Resistant mutants were obtained from penicillin-susceptible, intermediately resistant, and penicillin resistant strains. For cefixime, cefuroxime, cefpodoxime, cefotaxime, and ceftriaxone, the frequencies of mutation ranged from 10(-6) to 10(-8) when resistant mutants were selected at 2- to 8-fold the MIC, and the MICs increased 2- to 16-fold. For ampicillin, ampicillin-sulbactam, amoxicillin, amoxicillin-clavulanic acid, cefaclor, and loracarbef, the frequencies of mutation were about 10(-7) to 10(-8), and the MICs increased twofold at most. One to three resistance profiles of the resulting mutants were selected for each of the selecting antibiotics. Among those, some showed resistance to the cephalosporins associated with a 2- to 32-fold increase in susceptibility to the penicillins. Competition experiments showed a decreased affinity of PBP2x for cefpodoxime in all mutants. In some mutants that were more susceptible to amoxicillin, a decreased affinity of PBP2x for cefpodoxime was associated with an increased affinity for amoxicillin and a particular substitution of alanine for threonine at position 550 just after the KSG triad. From these results we infer (i) that among the beta-lactams tested the penicillins, cefaclor, and loracarbef selected one-step resistant mutants less frequently and that they achieved a lower level of resistance, and (ii) that mutants with different profiles may have acquired different point mutations in PBP2x.
Canine visceral leishmaniasis: successful chemotherapy induces macrophage antileishmanial activity via the L-arginine nitric oxide pathway
Authors: Vouldoukis I , Drapier J C , Nüssler A K , Tselentis Y , Da Silva O A , Gentilini M , Mossalayi D M , Monjour L , Dugas B
Published: October 2018

Following successful chemotherapy in canine visceral leishmaniasis, monocyte-derived macrophages can induce antileishmanial activity via a gamma interferon-dependent mechanism in the presence of autologous lymphocytes. The killing of leishmania correlated with the induction of the NO synthase pathway, because it correlated with the generation of nitrogen derivative production and was abrogated in the presence of NG-monomethyl-L-arginine, a competitive inhibitor of the NO synthase pathway. The level of L-citrulline in serum, which was produced after activation of the NO synthase pathway, was markedly enhanced in dogs receiving successful chemotherapy. Taken together, these data indicate that following successful chemotherapy of visceral leishmaniasis, leishmania parasites are killed by macrophages activated by gamma interferon-producing lymphocytes via an NO-dependent mechanism.
Comparison of fluconazole and amphotericin B for treatment of experimental Candida albicans endocarditis in rabbits
Authors: Chemlal K , Saint-Julien L , Joly V , Farinotti R , Seta N , Yeni P , Carbon C
Published: October 2018

Amphotericin B (AmB) and fluconazole, administered intraperitoneally for 7 days, were compared in a rabbit model for Candida albicans endocarditis. When given early, AmB was more effective than fluconazole for reducing CFU counts in vegetations (P < 0.01) and kidneys. Forty-eight hours after the last dose, AmB was still detected in all vegetations whereas fluconazole was detected in only one case.
Serum bactericidal activity of ceftazidime: continuous infusion versus intermittent injections
Authors: Nicolau D P , Nightingale C H , Banevicius M A , Fu Q , Quintiliani R
Published: October 2018

Since beta-lactam antibiotics have concentration-independent killing, bacterial eradication is a function of the time the serum drug concentration remains above the drug's MIC (T > MIC). We compared the serum bactericidal titers (SBTs) of ceftazidime given by continuous infusion (CI) or by intermittent bolus dosing (BD) against two clinical isolates each of Pseudomonas aeruginosa and Escherichia coli to determine if CI would allow lower daily dosing while still providing equal bactericidal activity compared with BD. This was an open-labeled, randomized, steady-state, four-way crossover study with 12 healthy volunteers. The ceftazidime regimens were 1 g every 8 h (q8h) BD, 1 g q12h BD, 3 g over 24 h CI, and 2 g over 24 h CI. The areas under the bactericidal curves were calculated by the trapezoidal rule using the reciprocal of the SBT. For all organisms the areas under the bactericidal curves for intermittent versus the CI regimens were the same for equal doses (P > 0.05). For both strains of E. coli all four regimens provided SBTs of > or = 1:2 over the dosing interval and 100% T > MIC. The 1-g q8h BD and q12h BD regimens provided T > MIC of 82 and 52%, respectively, for both P. aeruginosa isolates (MICs, 4 micrograms/ml). In comparison, the 2- and 3-g CI regimens always maintained SBTs of > or = 1:2 and T > MIC over the 24-h period as serum drug concentrations were 12.8 +/- 3.0 and 18.2 +/- 4.5 micrograms/ml, respectively. CI optimizes the pharmacodynamic and pharmacoeconomic profile of ceftazidime by providing adequate antibacterial activity over the 24-h dosing period with a reduction in the total daily dose of the antimicrobial agent.
Efficacy of UK-109496, a new azole antifungal agent, in an experimental model of invasive aspergillosis
Authors: George D , Miniter P , Andriole V T
Published: October 2018

The efficacy of UK-109496, a new azole antifungal agent, was evaluated in an immunosuppressed, temporarily leukopenic rabbit model of invasive aspergillosis. Oral therapy with UK-109496 at a dosage of 10 or 15 mg/kg of body weight every 8 h was begun 24 h after a lethal or sublethal challenge, and results were compared with those for amphotericin B therapy and untreated controls. UK-109496 eliminated mortality and also reduced the tissue burden of Aspergillus fumigatus 10- to 100-fold in liver and kidney tissues and to a lesser degree in lung tissue, and at the higher dose, no viable organisms were recovered from brain tissue from these animals. Both dosages of UK-109496 decreased or eliminated circulating antigen. The half-life of UK-109496 in rabbits was 2.5 to 3 h, and no accumulation of drug was seen even after 15 doses in either uninfected or infected animals. Thus, UK-109496 shows activity in this rabbit model of invasive aspergillosis. Additional studies are needed to determine the potential of the drug for use in the treatment of this infection.
Pharmacokinetics and metabolism of genaconazole, a potent antifungal drug, in men
Authors: Lin C , Kim H , Radwanski E , Affrime M , Brannan M , Cayen M N
Published: October 2018

The pharmacokinetics of genaconazole, a racemic triazole antifungal agent comprising 50% RR and 50% SS enantiomers, were studied in 12 healthy male volunteers after a single oral dose of 200 mg. The serum samples were analyzed for the two enantiomers by using a chiral high-pressure liquid chromatography assay. The concentrations of the RR and SS enantiomers in serum were virtually identical. The mean values for the maximum concentrations in serum (Cmax) (1.7 micrograms/ml), times to Cmax (4.0 to 4.2 h), half-lives (83 h), and areas under the concentration-time curve from 0 h to infinity (195 to 199 micrograms.h/ml) were similar for the two enantiomers. The results showed that the pharmacokinetic profiles of the two enantiomers were similar after a single oral dosing of the racemate. The pharmacokinetics of the RR enantiomer were also evaluated in 12 healthy male volunteers after a single oral dose of 100 or 200 mg. The ratios of the Cmaxs and of the areas under the concentration-time curves from 0 h to infinity for the two doses were about 2, indicating a dose proportionality. In a separate study, six healthy male volunteers received a single oral dose of 50 mg of 14C-labeled genaconazole. The Cmax values for total radioactivity (14C) and intact genaconazole were virtually identical (0.6 micrograms/ml). The mean half-lives in serum were about 73 h for both total radioactivity and genaconazole. The amounts of total radioactivity excreted in the 0 to 240-h interval (representing approximately three half-lives) in urine and feces were 66.6 and 9.3% of the dose, respectively; 64.4% of the dose was excreted in urine as parent drug. There were no detectable metabolites in either serum or urine. The data demonstrate that genaconazole (racemate) is well absorbed, undergoes negligible biotransformation, and is slowly excreted, primarily in the urine.
Plasmid-mediated formaldehyde resistance in Escherichia coli: characterization of resistance gene
Authors: Kümmerle N , Feucht H H , Kaulfers P M
Published: October 2018

The formaldehyde resistance mechanisms in the formaldehyde-resistant strain Escherichia coli VU3695 were investigated. A large (4.6-kb) plasmid DNA fragment encompassing the formaldehyde resistance gene was sequenced. A single 1,107-bp open reading frame encoding a glutathione- and NAD-dependent formaldehyde dehydrogenase was identified and sequenced, and the enzyme was expressed in an in vitro assay and purified. Amino acid sequence homology studies showed 62.4 to 63.2% identity with class III alcohol dehydrogenases isolated from horse, human, and rat livers. We demonstrated that the resistance mechanism in the formaldehyde-resistant strain E. coli VU3695 and in other formaldehyde-resistant members of the family Enterobacteriaceae is based on the enzymatic degradation of formaldehyde by a formaldehyde dehydrogenase.
Susceptibilities of Candida albicans multidrug transporter mutants to various antifungal agents and other metabolic inhibitors
Authors: Sanglard D , Ischer F , Monod M , Bille J
Published: October 2018

Some Candida albicans isolates from AIDS patients with oropharyngeal candidiasis are becoming resistant to the azole antifungal agent fluconazole after prolonged treatment with this compound. Most of the C. albicans isolates resistant to fluconazole fail to accumulate this antifungal agent, and this has been considered a cause of resistance. This phenomenon was shown to be linked to an increase in the amounts of mRNA of a C. albicans ABC (ATP-binding cassette) transporter gene called CDR1 and of a gene conferring benomyl resistance (BENr), the product of which belongs to the class of major facilitator multidrug efflux transporters (D. Sanglard, K. Kuchler, F. Ischer, J. L. Pagani, M. Monod, and J. Bille, Antimicrob. Agents Chemother. 39:2378-2386, 1995). To analyze the roles of these multidrug transporters in the efflux of azole antifungal agents, we constructed C. albicans mutants with single and double deletion mutations of the corresponding genes. The mutants were tested for their susceptibilities to these antifungal agents. Our results indicated that the delta cdr1 C. albicans mutant was hypersusceptible to the azole derivatives fluconazole, itraconazole, and ketoconazole, thus showing that the ABC transporter Cdr1 can use these compounds as substrates. The delta cdr1 mutant was also hypersusceptible to other antifungal agents (terbinafine and amorolfine) and to different metabolic inhibitors (cycloheximide, brefeldin A, and fluphenazine). The same mutant was slightly more susceptible than the wild type to nocodazole, cerulenin, and crystal violet but not to amphotericin B, nikkomycin Z, flucytosine, or pradimicin. In contrast, the delta ben mutant was rendered more susceptible only to the mutagen 4-nitroquinoline-N-oxide. However, this mutation increased the susceptibilities of the cells to cycloheximide and cerulenin when the mutation was constructed in a delta cdr1 background. The assay used in the present study could be implemented with new antifungal agents and is a powerful tool for assigning these substances as putative substrates of multidrug transporters.
Assessment of antiviral activity, efficacy, and toxicity of prostaglandin A2 in a rabbit model of herpetic keratitis
Authors: O'Brien W J , Taylor J L , Ankel H , Sitenga G
Published: October 2018

Prostaglandin A2 (PGA2) inhibited the replication of herpes simplex virus type 1 in rabbit and human cornea stromal cells at concentrations of 1 to 5 microM while causing significant toxicity at 55 to 150 microM. Despite favorable therapeutic indices in cultured cells, PGA2 was not effective as a therapeutic agent in the treatment of herpetic keratitis in a rabbit model. The sequelae of disease appeared more severe in animals receiving PGA2 than in untreated or placebo-treated controls. The recovery of virus from tissues of latently infected rabbits was not affected by therapy. PGA2 therapy alone induced breakdown of the blood-aqueous barrier, indicating that pharmacologically active concentrations of drug were achieved in the eye. Thus, PGA2 had antiviral activity, but its proinflammatory effects appeared to be more detrimental than beneficial in the treatment of herpetic keratitis.
Prenatal and postpartum pharmacokinetics of stavudine (2',3'-didehydro-3'-deoxythymidine) and didanosine (dideoxyinosine) in pigtailed macaques (Macaca nemestrina)
Authors: Odinecs A , Pereira C , Nosbisch C , Unadkat J D
Published: October 2018

Stavudine (5 mg/kg of body weight; n = 7) or didanosine (3.2 mg/kg; n = 4) was administered as an intravenous bolus to pregnant pigtailed macaques (Macaca nemestrina) near term and 4 to 5 weeks postpartum. No significant differences were found between the prenatal and postpartum total plasma drug clearance, steady-state volume of distribution, terminal plasma drug half-life, mean body residence time, or recovery of unchanged drug in urine. These data indicate that pregnancy does not affect the pharmacokinetics of stavudine or didanosine in M. nemestrina.
Implication of Ile-69 and Thr-182 residues in kinetic characteristics of IRT-3 (TEM-32) beta-lactamase
Authors: Farzaneh S , Chaibi E B , Peduzzi J , Barthelemy M , Labia R , Blazquez J , Baquero F
Published: October 2018

The substitution of a methionine for an isoleucine at position 69 (Met69Ile), which causes inhibitor resistance to TEM-type beta-lactamases (IRT-3 and IRT-I69), altered the positions of the Asn-170 and Glu-166 side chains as well as the position of the catalytic water molecule. A novel hydrogen bond between the hydroxyl of Thr-182 and the carbonyl of Glu-64 was expected to be responsible for the increase in the catalytic activity of the IST-T182 and IRT-3 enzymes compared with those of TEM-1 and IRT-169, respectively.
In vivo efficacy of oral and intralesional administration of 2-substituted quinolines in experimental treatment of new world cutaneous leishmaniasis caused by Leishmania amazonensis
Authors: Fournet A , Ferreira M E , Rojas De Arias A , Torres De Ortiz S , Fuentes S , Nakayama H , Schinini A , Hocquemiller R
Published: October 2018

The antileishmanial efficacies of 2-n-propylquinoline, chimanines B and D, 2-n-pentylquinoline, 2-phenylquinoline, 2-(3,4-methylenedioxyphenylethyl) quinoline, and two total alkaloidal extracts of Galipea longiflora were evaluated in BALB/c mice infected with Leishmania amazonensis or Leishmania venezuelensis. Animals were treated for 4 to 6 weeks postinfection with a quinoline by the oral route at 50 mg/kg of body weight twice daily for 15 days or by five intralesional injections at intervals of 4 days with a quinoline at 50 mg/kg of body weight. The reference drug, N-methylglucamine antimonate (Glucantime), was administered by subcutaneous or intralesional injection (regimens of 14, 28, or 56 mg of pentavalent antimony [Sbv] per kg of body weight daily). Twice-daily oral treatment with chimanine B at 50 mg/kg resulted in a decrease in lesion weight by 70% (P < 0.001) and a decrease in the parasite loads by 95% (P < 0.001). Five injections of chimanine B at intervals of 4 days reduced the lesion weight by 74% and the parasite loads in the lesion by 90% compared with the values for the group of untreated mice. Subcutaneous administration of N-methylglucamine antimonate at 28 mg of Sbv kg per day for 15 days reduced the parasite burden by 95% (P < 0.001), and five intralesional injections at the same concentration reduced the parasite burden by 96% (P < 0.001). Other 2-substituted quinolines, 2-n-propylquinoline administered by the oral and intralesional routes, 2-phenylquinoline administered by the oral route, 2-n-pentylquinoline administered by intralesional injection, and two total alkaloidal extracts of G. longiflora administered by the oral route, had intermediate effects. These findings suggest that chimanine B may be chosen as a lead molecule in the development of oral therapy against leishmaniasis.
In vitro interaction between amphotericin B and azoles in Candida albicans
Authors: Vazquez J A , Arganoza M T , Vaishampayan J K , Akins R A
Published: October 2018

The use of azole prophylaxis as a measure to prevent invasive fungal infections in high-risk patients is increasing and is now the standard of care in many institutions. Previous studies disagree on whether preexposure of Candida albicans to azoles affects their subsequent susceptibility to amphotericin B (AmB). The present in vitro study indicates that azole exposure generates a subpopulation of cells that are not affected by subsequent exposure to AmB. These cells that are phenotypically resistant to AmB tolerated by most cells not exposed to azole. The percentage of cells that convert to phenotypic resistance to AmB varies with the concentration and the azole. Itraconazole is more effective than fluconazole in generating cells that are phenotypically resistant to AmB and that tolerate an otherwise lethal transient exposure to AmB. Until cells that are not exposed to fluconazole are simultaneously challenged with AmB, they are not protected to a significant extent from killing by AmB. Cells that are challenged with continuous exposure to AmB also acquire phenotypic resistance to AmB at increased frequencies by azole preexposure, but this requires that the azole be continuously present during incubation with AmB. In addition, Candida cells taken from mature colonies that are not actively growing are not susceptible to the short-term killing effects of AmB without azole preexposure. The adaptive responses of C. albicans to AmB and potentially other antifungal agents that may result from prior exposure to azoles in vitro or potentially in microenvironments in vivo that induce physiological changes may have major clinical implications.