Does lithium attenuate the liver damage due to oxidative stress and liver glycogen depletion in experimental common bile duct obstruction?

In extrahepatic cholestasis, the molecular mechanisms of liver damage due to bile acid accumulation remain elusive. In this study, the activation of glutamatergic receptors was hypothesized to be responsible for bile acid-induced oxidative stress and liver damage. Recent evidence showed that lithium, as an N-methyl-d-aspartate receptor (NMDAR) GluN2B subunit inhibitor, may act on the glutamate/NMDAR signaling axis. Guinea pigs were assigned to four groups, as sham laparotomy (SL), bile duct ligated (BDL), lithium-treated SL (SL + Li) and lithium-treated BDL (BDL + Li) groups. Cholestasis-induced liver injury was evaluated by aspartate aminotransferase (AST), alanine transaminase (ALT), interleukin-6 (IL-6), tissue malondialdehyde (MDA), copper­zinc superoxide dismutase and reduced glutathione levels. The liability of glutamate/NMDAR signaling axis was clarified by glutamate levels in both plasma and liver samples, with the production of nitric oxide (NO), as well as with the serum calcium concentrations. Blood glucose, glucagon, insulin levels and glucose consumption rates, in addition to tissue glycogen were measured to evaluate the liver glucose-glycogen metabolism. A high liver damage index (AST/ALT) was calculated in BDL animals in comparison to SL group. In the BDL animals, lithium reduced plasma NO and glutamate in addition to tissue glutamate concentrations, while serum calcium increased. The antioxidant capacities and liver glycogen contents significantly increased, whereas blood glucose levels unchanged and tissue MDA levels decreased 3-fold in lithium-treated cholestatic animals. It was concluded that lithium largely protects the cholestatic hepatocyte from bile acid-mediated damage by blocking the NMDAR-GluN2B subunit.

Effects of co-selection of antibiotic-resistance and metal-resistance genes on antibiotic-resistance potency of environmental bacteria and related ecological risk factors.

The inadequate elimination of micropollutants in wastewater treatment plants (WWTP), cause to increase in the incidence of antibiotic resistant bacterial strains. Growth of microbial pathogens in WWTP is one of the serious public health problems. The widespread and simultaneous emergence of antibiotic resistance genes (ARGs) and heavy metal resistance genes (HMRGs) in the environment with heavy metals create persistent and selective pressure for co-selection of both genes on environmental microorganisms. Co-localization of ARGs and HMRGs on the same horizontal mobile genetic elements (MGEs) allows the spreading of numerous antibiotic-resistant strains of bacteria in aquatic and terrestrial environment. The biofilm formation and colonization potential of environmental bacteria leads to the co-selection of multi-antibiotic resistance and multi-metal tolerance. Horizontal gene transfer (HGT), co-localization of both ARGs and HMRGs on the same MGEs, and the shared resistomes are important bacteria-associated ecological risks factors, which reduce the effectiveness of antibiotics against bacterial infections.

Can iron, zinc, copper and selenium status be a prognostic determinant in COVID-19 patients?

In severe COVID-19, the levels of iron (Fe), copper (Cu), zinc (Zn) and selenium (Se), do not only regulate host immune responses, but modify the viral genome, as well. While low serum Fe concentration is an independent risk factor for the increased death rate, Zn controls oxidative stress, synthesis of inflammatory cytokines and viral replication. Therefore, Zn deficiency associates with a worse prognosis. Although Cu exposure inactivates the viral genome and exhibits spike protein dispersal, increase in Cu/Zn due to high serum Cu levels, are correlated with enhanced risk of infections. Se levels are significantly higher in surviving COVID-19 patients. Meanwhile, both Zn and Se suppress the replication of SARS-CoV-2. Since the balance between the deficiency and oversupply of these metals due to a reciprocal relationship, has decisive effect on the prognosis of the SARS-CoV-2 infection, monitoring their concentrations may facilitate improved outcomes for patients suffering from COVID-19.

Current opinion in neurological manifestations of SARS-CoV-2 infection.

Neurological symptoms occur in approximately one-third of hospitalized patients with coronavirus disease 2019 (COVID-19). Among these symptoms, hypoxic encephalopathy develops in one-fifth of severe cases, while ischemic strokes due to thrombotic complications are common in one-third of COVID-19 intensive care patients. Brain involvement of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is eventuated by several routes, including hematogenous spread, transsynaptic entry through infected neurons, olfactory nerve, ocular epithelium, vascular endothelium, and impaired blood-brain barrier. Besides the high angiotensin-converting enzyme-2 (ACE2) binding affinity, and FURIN preactivation, SARS-CoV-2 maintains efficient neuronal entry while evading immune surveillance by using basigin and neuropilin-1 receptors. However, the neurological manifestations and their pathogenic mechanisms are still debated in COVID-19 patients.

The effect of environmental diesel exhaust pollution on SARS-CoV-2 infection: The mechanism of pulmonary ground glass opacity.

Diesel exhaust particles (DEP) are the major components of atmospheric particulate matter (PM) and chronic exposure is recognized to enhance respiratory system complications. Although the spread of SARS-CoV-2 was found to be associated with the PMs, the mechanism by which exposure to DEP increases the risk of SARS-CoV-2 infection is still under discussion. However, diesel fine PM (dPM) elevate the probability of SARS-CoV-2 infection, as it coincides with the increase in the number of ACE2 receptors. Expression of ACE2 and its colocalized activator, transmembrane protease serine 2 (TMPRSS2) facilitate the entry of SARS-CoV-2 into the alveolar epithelial cells exposed to dPM. Thus, the coexistence of PM and SARS-CoV-2 in the environment augments inflammation and exacerbates lung damage. Increased TGF-ß1 expression due to DEP accompanies the proliferation of the extracellular matrix. In this case, "multifocal ground-glass opacity" (GGO) in a CT scan is an indication of a cytokine storm and severe pneumonia in COVID-19.

Bacterial Protein Kinases.

Bacteria are able to inhabit and survive vastly diverse environments. This enormous adaptive capacity depend on their ability to perceive cues from the micro-environment and process this information accordingly to mount appropriate metabolic responses and ultimately sustain homeostasis. From systems perspective, microbial cells conceal significant degree of organismal complexity, which may only be managed by continuous bulk cellular information flow and processing, inside the cell, between other cells and the environment. In this respect, reversible covalent modification of proteins is one of the universal mode of information flow mechanism used to regulate metabolism in all organisms. More than 30 types of post translational modifications have been identified, where phosphorylation constitutes nearly half of them. Bacterial cells possess several modes of phosphoprotein mediated information flow mechanisms. Histidine kinases and two component systems, bacterial tyrosine kinases, Hanks type serine/threonine kinases, atypical serine kinases and arginine kinases have been identified in many species.

The effect of environmental pollution on immune evasion checkpoints of SARS-CoV-2.

Many diverse strategies allow and facilitate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to evade antiviral innate immune mechanisms. Although the type I interferon (IFN) system has a critical role in restricting the dissemination of viral infection, suppression of IFN receptor signals by SARS-CoV-2 constitutes a checkpoint that plays an important role in the immune escape of the virus. Environmental pollution not only facilitates SARS-CoV-2 infection but also increases infection-associated fatality risk, which arises due to Systemic Aryl hydrocarbon Receptor (AhR) Activation Syndrome. The intracellular accumulation of endogenous kynurenic acid due to overexpression of the indoleamine 2,3-dioxygenase (IDO) by AhR activation induces AhR-interleukin-6 (IL-6)-signal transducers and activators of the transcription 3 (STAT3) signaling pathway. The AhR-IDO1-Kynurenine pathway is an important checkpoint, which leads to fatal consequences in SARS-CoV-2 infection and immune evasion in the context of Treg/Th17 imbalance and cytokine storm.

Dual function of sialic acid in gastrointestinal SARS-CoV-2 infection.

Recent analysis concerning the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)- angiotensin converting enzyme (ACE) receptor interaction in enterocytes, the definition of gut-lung axis, as well as the molecular basis of sialic acid-related dual recognition concept in gastrointestinal SARS-CoV-2 infection, have brought a new perspective to potential therapeutic targets. In this review evolving research and clinical data on gastrointestinal SARS-CoV-2 infection are discussed in the context of viral fusion and entry mechanisms, focusing on the different triggers used by coronaviruses. Furthermore, it is emphasized that the viral spike protein is prevented from binding gangliosides, which are composed of a glycosphingolipid with one or more sialic acids, in the presence of chloroquine or hydroxychloroquine. In gastrointestinal SARS-CoV-2 infection the efficiency of these repositioned drugs is debated.

Two important controversial risk factors in SARS-CoV-2 infection: Obesity and smoking.

The effects of obesity and smoking in the coronavirus disease 2019 (COVID-19) pandemic remain controversial. Angiotensin converting enzyme 2 (ACE2), a component of the renin-angiotensin system (RAS), is the human cell receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19. ACE2 expression increases on lung alveolar epithelial cells and adipose tissue due to obesity, smoking and air pollution. A significant relationship exists between air pollution and SARS-CoV-2 infection, as more severe COVID-19 symptoms occur in smokers; comorbid conditions due to obesity or excess ectopic fat accumulation as underlying risk factors for severe COVID-19 strongly encourage the virus/ACE2 receptor-ligand interaction concept. Indeed, obesity, air pollution and smoking associated risk factors share underlying pathophysiologies that are related to the Renin-Angiotensin-System in SARS-CoV-2 infection. The aim of this review is to emphasize the mechanism of receptor-ligand interaction and its impact on the enhanced risk of death due to SARS-CoV-2 infection.

The use of multiplexing technology in the immunodiagnosis of infectious agents.

Traditionally, definitive diagnosis of infectious diseases is made by cultivation of the causative agent, while various antigens and antibodies as biomarkers of various diseases are detected by commercially available ELISA kits. PCR has emerged as a major innovation that greatly accelerated the accumulation of genomic and transcriptomic data, yet it has also revolutionized microbial diagnostics by enabling the detection of pathogen nucleic acid. Despite the advantages of and vast experience in ELISA and PCR, the next generation research and diagnostic tools have to fulfill the requirements of systems and synthetic biology era. Multiplex bead assays hold this promise by providing a more complete multi-parametric picture of the biological phenomenon of interest at a fraction of time, sample volume and cost required for conventional assay systems. To date, numerous multiplex bead assays have been described to detect multiple antigen, antibody and nucleic acid targets of both microbial pathogens and immune response. These assays have been successfully used in diagnostic, cohort screening and research setups.

N-Methyl-D aspartate receptor-mediated effect on glucose transporter-3 levels of high glucose exposed-SH-SY5Y dopaminergic neurons.

High glucose and insulin lead to neuronal insulin resistance. Glucose transport into the neurons is achieved by regulatory induction of surface glucose transporter-3 (GLUT3) instead of the insulin. N-methyl-D aspartate (NMDA) receptor activity increases GLUT3 expression. This study explored whether an endogenous NMDA receptor antagonist, kynurenic acid (KynA) affects the neuronal cell viability at high glucose concentrations. SH-SY5Y neuroblastoma cells were exposed to 150-250 mg/dL glucose and 40 µU/mL insulin. In KynA and N-nitro-l-arginine methyl ester (L-NAME) supplemented cultures, oxidative stress, mitochondrial metabolic activity (MTT), nitric oxide as nitrite+nitrate (NOx) and GLUT3 were determined at the end of 24 and 48-h incubation periods. Viable cells were counted by trypan blue dye. High glucose-exposed SH-SY5Y cells showed two-times more GLUT3 expression at second 24-h period. While GLUT3-stimulated glucose transport and oxidative stress was increased, total mitochondrial metabolic activity was significantly reduced. Insulin supplementation to high glucose decreased NOx synthesis and GLUT3 levels, in contrast oxidative stress increased three-fold. KynA significantly reduced oxidative stress, and increased MTT by regulating NOx production and GLUT3 expression. KynA is a noteworthy compound, as an endogenous, specific NMDA receptor antagonist; it significantly reduces oxidative stress, while increasing cell viability at high glucose and insulin concentrations.

Microbiota and Lipotoxicity.

Obesity and metabolic syndrome is a multisystemic disorder, that is characterized by excess caloric intake and spillover lipotoxicity caused by ectopic lipid accumulation in non-adipose tissues. Low grade chronic inflammation and insulin resistance are the hallmarks of the disorder, which further aggravate the condition. Gut microbiota constitutes an indispensible part of human superorganism's energy harvesting apparatus. The dynamic composition of microbiota changes with age, life style and host metabolic background. The wealth of genetic repertoire provided by these microorganism enables to extend host's substrate processing and harvesting capability. Some of these compounds including short chain fatty acids and indole act as signalling molecules on mammalian cells and modulate their behaviour. Nonetheless, this symbiotic style of interaction is restrained by immune system. The role of chronic low grade inflammation in metabolic syndrome is well established. Treg cells are the key players that sense and reshape the composition of microbiota. In this regard, any disturbance in Treg functionality may aggravate the inflammation and shift the symbiotic balance towards dysbiosis, which is characterized by autoimmunity and insulin resistance. Thus, immune system is responsible for the modulation of host and microbiota metabolisms and Treg cells act as a bridge in between.

Glutamate­mediated effects of caffeine and interferon­Î³ on mercury-induced toxicity.

The molecular mechanisms mediating mercury­induced neurotoxicity are not yet completely understood. Thus, the aim of this study was to investigate whether the severity of MeHg­ and HgCl2­mediated cytotoxicity to SH­SY5Y human dopaminergic neurons can be attenuated by regulating glutamate­mediated signal­transmission through caffeine and interferon­Î³ (IFN­Î³). The SH­SY5Y cells were exposed to 1, 2 and 5 µM of either MeHgCl2 or HgCl2 in the presence or absence of L­glutamine. To examine the effect of adenosine receptor antagonist, the cells were treated with 10 and 20 µM caffeine. The total mitochondrial metabolic activity and oxidative stress intensity coefficient were determined in the 1 ng/ml IFN­Î³­ and glutamate­stimulated SH­SY5Y cells. Following exposure to mercury, the concentration­dependent decrease in mitochondrial metabolic activity inversely correlated with oxidative stress intensity. MeHg was more toxic than HgCl2. Mercury­induced neuronal death was dependent on glutamate­mediated excitotoxicity. Caffeine reduced the mercury­induced oxidative stress in glutamine-containing medium. IFN­Î³ treatment decreased cell viability and increased oxidative stress in glutamine­free medium, despite caffeine supplementation. Although caffeine exerted a protective effect against MeHg-induced toxicity with glutamate transmission, under co­stimulation with glutamine and IFN­Î³, caffeine decreased the MeHg­induced average oxidative stress only by half. Thereby, our data indicate that the IFN­Î³ stimulation of mercury­exposed dopaminergic neurons in neuroinflammatory diseases may diminish the neuroprotective effects of caffeine.

The role of interleukin-1 gene polymorphisms and Helicobacter pylori in gastroesophageal reflux disease.

BACKGROUND/AIMS: Our aim is to assess the relationship between interleukin 1ß (IL-1 ß), (-511,-31 alleles), interleukin 1RN (IL-RN), Helicobacter pylori (HP) status and gastroesophageal reflux disease (GERD) diagnosed by pH monitoring in the Turkish population. MATERIALS AND METHODS: A Total of 100 consecutive patients with GERD were enrolled in the study. Genotypes of IL-1ß (-511,-31), IL-1RN gene polymorphisms and HP status of the patients were analyzed. RESULTS: While thirty-two patients were diagnosed as esophagitis with varying severity the remaining patients had no esophagitis. Seventy six participants were positive for HP and the remaining patients were negative. The difference between erosive and non-erosive groups was statistically significant when we compared IL-1ß (-511) but no difference regarding IL-1ß (-31) and IL-1RN variations. We also analyzed T/T, C/T and C/C alleles and the difference was significant statistically in T/T allele between patients with and without erosive GERD 1 (3.1%) vs. 12 (17.9%), respectively with a p value<0.05. But C/C, C/T alleles of (-511), (-31) and IL-1RN polymorphisms were not statistically significant between the groups. CONCLUSION: IL-1ß genetic polymorphisms may take part in the pathophysiology of gastroesophageal reflux disease.

[Investigation of the Presence of Disinfectant Resistance Genes qacA/B in Nosocomial Methicillin-Resistant Staphylococcus aureus Isolates and Evaluation of Their In Vitro Disinfectant Susceptibilities]. / Hastane Enfeksiyonu Etkeni Olan Metisiline Dirençli Staphylococcus aureus Suslarinda qacA/B Dezenfektan Direnç Genlerinin Varligi ve Dezenfektanlara In Vitro Duyarliliklarinin Arastirilmasi

Development of resistance to disinfectant substances in nosocomial microorganisms is an important problem encountered during disinfectant practices. Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant cause of hospital-acquired infections. Besides being resistant to several antimicrobial agents, MRSA strains can also become resistant to some disinfectant substances. Resistance to disinfectant substances may develop due to the misuse of disinfectants. This may either be due to the frequent use of disinfectant substances or use in lower concentrations than recommended. MRSA strains may harbour the qacA/B disinfectant resistance genes that may cause resistance to quarternary ammonium compounds and some cationic disinfectants. These resistance genes are found in plasmids and are responsible for decreased susceptibility or resistance. In this study, a total of 69 nosocomial MRSA strains isolated from clinical specimens in our hospital were tested for disinfectant activity and the presence of qacA/B disinfectant resistance genes in these isolates was investigated by polymerase chain reaction. We determined whether the presence of these genes caused phenotypic resistance to chlorhexidine and benzalkonium chloride by the use of bactericidal and bacteriostatic tests. For this purpose, the minimum inhibitory concentration (MIC) values of these disinfectants against MRSA isolates were detected by microdilution method with the proposals of CLSI, and bactericidal effects of these disinfectants were also detected by using quantitative suspension test according to EN13727:2003 European Standard. It has been found that 11.6% (8/69) of the isolates harbored qacA/B resistance genes. MIC values for chlorhexidine and benzalkonium chloride were found in the range of 2-8 µg/ml. Although it was observed that MIC values were higher in five of the qacA/B gene positive isolates, statistically significant difference was not found between gene positive and gene negative groups. Both 1% chlorhexidine and 1% benzalkonium chloride were found bactericidal against the isolates including the ones carrying the qacA/B resistance genes. It was concluded that the presence of the qacA/B disinfectant resistance genes did not lead to resistance to the disinfectant substances at the concentrations used in clinical practices. Furthermore, tested disinfectants still exhibited bactericidal activity even with high MIC values.

Detection of Helicobacter pylori DNA in aortic and left internal mammary artery biopsies.

We investigated the relationship between acute coronary ischemia and the presence of Helicobacter pylori DNA in aortic regions that were absent macroscopic atheromatous plaques. The study group (Group 1) consisted of 42 patients who underwent coronary artery bypass grafting. Biopsy samples were obtained from 2 different locations: from regions of the aorta that were free (macroscopically) of atheromatous plaque (Group 1A), and from the internal mammary artery (Group 1B). The control group (Group 2) of 10 patients who had no atherosclerotic vascular disease provided aortic tissue samples for comparison. The real-time polymerase chain reaction method was used to detect H. pylori DNA in all biopsy samples. Eleven of 42 aortic tissue samples (26%) in Group 1A were positive for H. pylori DNA. Neither biopsies from the left internal mammary arteries of those patients nor biopsies from the aortas of the control group (Group 2) were positive for H. pylori DNA. There was a statistically significant difference between 1A and 1B in terms of H. pylori positivity (P=0.001). In Group 1 as a whole, acute coronary ischemia was more prevalent in the H. pylori-positive patients than in the H. pylori-negative patients (P=0.001). To our knowledge, this is the 1st study to investigate the detection of H. pylori DNA in aortic biopsy samples that are macroscopically free of atheromatous plaque. Such detection in patients who have atherosclerotic coronary artery disease could be an important indication of the role of microorganisms in the pathogenesis of atherosclerosis.

Effects of atypical pneumonia agents on progression of atherosclerosis and acute coronary syndrome.

BACKGROUND: The aim of this study was to investigate the presence of various atypical pneumonia agents (Chlamydia pneumoniae, cytomegalovirus, Mycoplasma pneumoniae), which are considered to have a role in the ethiopathogenesis of atherosclerosis, in aortic biopsies without macroscopically visible plaque and in internal thoracic artery biopsies. MATERIAL AND METHODS: Thirty-three patients (group 1), who had undergone coronary bypass operation and 10 non-atherosclerotic patients (group 2), were included in the study. Seventy-six tissue biopsies were taken. Biopsies from the patients in group 1 a were obtained from the atheroma plaque-free aortic tissue and 33 biopsies (group Ib) were obtained from their internal thoracic arteries. Following DNA extraction, nested PCR was used to detect Chlamydia pneumoniae DNA, and real time PCR was used to detect cytomegalovirus and Mycoplasma pneumoniae DNA. Blood parameters (lipid profile, CRP, fibrinogen) of the patients and operation characteristics were recorded. RESULTS: Chlamydia pneumoniae DNA was detected in 5 of 33 biopsy samples from coronary bypass patients, whereas none of the control patients (group 1b and group 2) were positive for this agent (P = 0.001). Neither CMV nor Mycoplasma pneumoniae was detected in IMA and aortic biopsies of both bypass and control patients. Elevated total cholesterol levels (P = 0.02) and positive CRP (P = 0.001) was found in C. pneumoniae positive patients. Prevalence of acute coronary syndrome was significantly higher in C. pneumoniae detected patients compared (P = 0.00 1). CONCLUSIONS: Detection of C. pneumoniae DNA in the atheroma free aortic biopsies might indicate that this micro-organism intervened in the progression of atheroma plaque. There was a strong relationship between the detection of this micro-organism in the aortic wall and acute coronary syndrome. The absence of DNA of the corresponding micro-organisms in the IMA wall may show its resistance to infective agents and in turn to atherosclerosis, which is a result of the prevailing endothelial functions of this artery.