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), copper‑zinc 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.

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-β1 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.

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.

Combined Toxicity of Metal Nanoparticles: Comparison of Individual and Mixture Particles Effect

Toxicity of metal nanoparticles (NPs) are closely associated with increasing intracellular reactive oxygen species (ROS) and the levels of pro-inflammatory mediators. However, NP interactions and surface complexation reactions alter the original toxicity of individual NPs. To date, toxicity studies on NPs have mostly been focused on individual NPs instead of the combination of several species. It is expected that the amount of industrial and highway-acquired NPs released into the environment will further increase in the near future. This raises the possibility that various types of NPs could be found in the same medium, thereby, the adverse effects of each NP either could be potentiated, inhibited or remain unaffected by the presence of the other NPs. After uptake of NPs into the human body from various routes, protein kinases pathways mediate their toxicities. In this context, family of mitogen-activated protein kinases (MAPKs) is mostly efficient. Despite each NP activates almost the same metabolic pathways, the toxicity induced by a single type of NP is different than the case of co-exposure to the combined NPs. The scantiness of toxicological data on NPs combinations displays difficulties to determine, if there is any risk associated with exposure to combined nanomaterials. Currently, in addition to mathematical analysis (Response surface methodology; RSM), the quantitative-structure-activity relationship (QSAR) is used to estimate the toxicity of various metal oxide NPs based on their physicochemical properties and levels applied. In this chapter, it is discussed whether the coexistence of multiple metal NPs alter the original toxicity of individual NP. Additionally, in the part of "Toxicity of diesel emission/exhaust particles (DEP)", the known individual toxicity of metal NPs within the DEP is compared with the data regarding toxicity of total DEP mixture.

The effect of environmental Bisphenol A exposure on breast cancer associated with obesity

Bisphenol A (BPA) is a widely used endocrine disrupter. Its environmental exposure is a causative factor of cell aging via decreasing telomerase activity, thus leading to shortening of telomere length. Epidemiological studies confirm positive associations between BPA exposure and the incidence of obesity and type 2 diabetes (T2DM). Increased urinary BPA levels in obese females are both significantly correlated with shorter relative telomere length and T2DM. BPA is a critically effective endocrine disrupter leading to poor prognosis via the obesity-inflammation-aromatase axis in breast cancer. Environmental BPA exposure contributes to the progression of both estrogen dependent and triple negative breast cancers. BPA is a positive regulator of human telomerase reverse transcriptase (hTERT) and it increases the expression of hTERT mRNA in breast cancer cells. BPA exposure can lead to tamoxifen resistance. Among patients treated with chemotherapy, those with persistent high telomerase activity due to BPA are at higher risk of death.

Protein Kinases Signaling in Pancreatic Beta-cells Death and Type 2 Diabetes

Type 2 diabetes (T2D) is a worldwide serious public health problem. Insulin resistance and β-cell failure are the two major components of T2D pathology. In addition to defective endoplasmic reticulum (ER) stress signaling due to glucolipotoxicity, β-cell dysfunction or β-cell death initiates the deleterious vicious cycle observed in T2D. Although the primary cause is still unknown, overnutrition that contributes to the induction of the state of low-grade inflammation, and the activation of various protein kinases-related metabolic pathways are main factors leading to T2D. In this chapter following subjects, which have critical checkpoints regarding β-cell fate and protein kinases pathways are discussed; hyperglycemia-induced β-cell failure, chronic accumulation of unfolded protein in β-cells, the effect of intracellular reactive oxygen species (ROS) signaling to insulin secretion, excessive saturated free fatty acid-induced β-cell apoptosis, mitophagy dysfunction, proinflammatory responses and insulin resistance, and the reprogramming of β-cell for differentiation or dedifferentiation in T2D. There is much debate about selecting proposed therapeutic strategies to maintain or enhance optimal β-cell viability for adequate insulin secretion in T2D. However, in order to achieve an effective solution in the treatment of T2D, more intensive clinical trials are required on newer therapeutic options based on protein kinases signaling pathways.

The Connection Between Cell Fate and Telomere

Abolition of telomerase activity results in telomere shortening, a process that eventually destabilizes the ends of chromosomes, leading to genomic instability and cell growth arrest or death. Telomere shortening leads to the attainment of the "Hayflick limit", and the transition of cells to state of senescence. If senescence is bypassed, cells undergo crisis through loss of checkpoints. This process causes massive cell death concomitant with further telomere shortening and spontaneous telomere fusions. In functional telomere of mammalian cells, DNA contains double-stranded tandem repeats of TTAGGG. The Shelterin complex, which is composed of six different proteins, is required for the regulation of telomere length and stability in cells. Telomere protection by telomeric repeat binding protein 2 (TRF2) is dependent on DNA damage response (DDR) inhibition via formation of T-loop structures. Many protein kinases contribute to the DDR activated cell cycle checkpoint pathways, and prevent DNA replication until damaged DNA is repaired. Thereby, the connection between cell fate and telomere length-associated telomerase activity is regulated by multiple protein kinase activities. Contrarily, inactivation of DNA damage checkpoint protein kinases in senescent cells can restore cell-cycle progression into S phase. Therefore, telomere-initiated senescence is a DNA damage checkpoint response that is activated with a direct contribution from dysfunctional telomeres. In this review, in addition to the above mentioned, the choice of main repair pathways, which comprise non-homologous end joining and homologous recombination in telomere uncapping telomere dysfunctions, are discussed.

Alzheimer's Disease and Protein Kinases

Alzheimer's disease (AD) is the most common neurodegenerative disorder and accounts for more than 60-80% of all cases of dementia. Loss of pyramidal neurons, extracellular amyloid beta (Abeta) accumulated senile plaques, and neurofibrillary tangles that contain hyperphosphorylated tau constitute the main pathological alterations in AD.Synaptic dysfunction and extrasynaptic N-methyl-D-aspartate receptor (NMDAR) hyperactivation contributes to excitotoxicity in patients with AD. Amyloid precursor protein (APP) and Abeta promoted neurodegeneration develop through the activation of protein kinase signaling cascade in AD. Furthermore, ultimate neuronal death in AD is under control of protein kinases-related signaling pathways. In this chapter, critical check-points within the cross-talk between neuron and protein kinases have been defined regarding the initiation and progression of AD. In this context, amyloid cascade hypothesis, neuroinflammation, oxidative stress, granulovacuolar degeneration, loss of Wnt signaling, Abeta-related synaptic alterations, prolonged calcium ions overload and NMDAR-related synaptotoxicity, damage signals hypothesis and type-3 diabetes are discussed briefly.In addition to clinical perspective of AD pathology, recommendations that might be effective in the treatment of AD patients have been reviewed.

N-Methyl-D-Aspartate Receptor Signaling-Protein Kinases Crosstalk in Cerebral Ischemia

Although stroke is very often the cause of death worldwide, the burden of ischemic and hemorrhagic stroke varies between regions and over time regarding differences in prognosis, prevalence of risk factors, and treatment strategies. Excitotoxicity, oxidative stress, dysfunction of the blood-brain barrier, neuroinflammation, and lysosomal membrane permeabilization, sequentially lead to the progressive death of neurons. In this process, protein kinases-related checkpoints tightly regulate N-methyl-D-aspartate (NMDA) receptor signaling pathways. One of the major hallmarks of cerebral ischemia is excitotoxicity, characterized by overactivation of glutamate receptors leading to intracellular Ca²⁺ overload and ultimately neuronal death. Thus, reduced expression of postsynaptic density-95 protein and increased protein S-nitrosylation in neurons is responsible for neuronal vulnerability in cerebral ischemia. In this chapter death-associated protein kinases, cyclin-dependent kinase 5, endoplasmic reticulum stress-induced protein kinases, hyperhomocysteinemia-related NMDA receptor overactivation, ephrin-B-dependent amplification of NMDA-evoked neuronal excitotoxicity and lysosomocentric hypothesis have been discussed.Consequently, ample evidences have demonstrated that enhancing extrasynaptic NMDA receptor activity triggers cell death after stroke. In this context, considering the dual roles of NMDA receptors in both promoting neuronal survival and mediating neuronal damage, selective augmentation of NR2A-containing NMDA receptor activation in the presence of NR2B antagonist may constitute a promising therapy for stroke.

Indoleamine 2,3-Dioxygenase Activity-Induced Acceleration of Tumor Growth, and Protein Kinases-Related Novel Therapeutics Regimens

Indoleamine 2,3-dioxygenase (IDO) is overexpressed in response to interferon-gamma (IFN-γ). IDO-mediated degradation of tryptophan (Trp) along the kynurenine (Kyn) pathway by immune cells is associated with the anti-microbial, and anti-tumor defense mechanisms. In contrast, IDO is constitutively expressed by various tumors and creates an immunosuppressive microenvironment around the tumor tissue both by depletion of the essential amino acid Trp and by formation of Kyn, which is immunosuppressive metabolite of Trp. IDO may activate its own expression in human cancer cells via an autocrine aryl hydrocarbon receptor (AhR)- interleukin 6 (IL-6)-signal transducer and activator of transcription 3 (STAT3) signaling loop. Although IDO is not a unique marker, in many clinical trials serum IDO activity is suggested to be an important parameter in the pathogenesis of cancer development and growth. Measuring IDO activity in serum seems to be an indicator of cancer growth rate, however, it is controversial whether this approach can be used as a reliable guide in cancer patients treated with IDO inhibitors. Thus, IDO immunostaining is strongly recommended for the identification of higher IDO producing tumors, and IDO inhibitors should be included in post-operative complementary therapy in IDO positive cancer cases only. Novel therapies that target the IDO pathway cover checkpoint protein kinases related combination regimens. Currently, multi-modal therapies combining IDO inhibitors and checkpoint kinase blockers in addition to T regulatory (Treg) cell-modifying treatments seem promising.

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.

Nanoantibiotics: A Novel Rational Approach to Antibiotic Resistant Infections

Background:

The main drawbacks for using conventional antimicrobial agents are the development of multiple drug resistance due to the use of high concentrations of antibiotics for extended periods. This vicious cycle often generates complications of persistent infections, and intolerable antibiotic toxicity. The problem is that while all new discovered antimicrobials are effective and promising, they remain as only short-term solutions to the overall challenge of drug-resistant bacteria.

Objective:

Recently, nanoantibiotics (nAbts) have been of tremendous interest in overcoming the drug resistance developed by several pathogenic microorganisms against most of the commonly used antibiotics. Compared with free antibiotic at the same concentration, drug delivered via a nanoparticle carrier has a much more prominent inhibitory effect on bacterial growth, and drug toxicity, along with prolonged drug release. Additionally, multiple drugs or antimicrobials can be packaged within the same smart polymer which can be designed with stimuli-responsive linkers. These stimuli-responsive nAbts open up the possibility of creating multipurpose and targeted antimicrobials. Biofilm formation still remains the leading cause of conventional antibiotic treatment failure. In contrast to conventional antibiotics nAbts easily penetrate into the biofilm, and selectively target biofilm matrix constituents through the introduction of bacteria specific ligands. In this context, various nanoparticles can be stabilized and functionalized with conventional antibiotics. These composites have a largely enhanced bactericidal efficiency compared to the free antibiotic.

Conclusion:

Nanoparticle-based carriers deliver antibiotics with better biofilm penetration and lower toxicity, thus combating bacterial resistance. However, the successful adaptation of nanoformulations to clinical practice involves a detailed assessment of their safety profiles and potential immunotoxicity.

Nanoparticles and neurotoxicity: Dual response of glutamatergic receptors

Although the use of nanoparticles for neuro-diagnostic and neurotherapeutic purposes provides superior benefits than the conventional approaches, it may be potentially toxic in central nervous system. In this respect, nanotechnological research focuses on nanoneurotoxicity-nanoneurosafety concepts. Despite these efforts, nanoparticles (NPs) may cause neurotoxicity, neuroinflammation, and neurodegeneration by penetrating the brain-olfactory route and blood-brain barrier (BBB). Indeed, due to their unique structures nanomaterials can easily cross biological barriers, thus avoid drug delivery problems. Despite the advancement of nanotechnology for designing therapeutic agents, toxicity of these nanomaterials is still a concern. Activation of neurons by astrocytic glutamate is a result of NPs-mediated astrocyte-neuron crosstalk. Increased extracellular glutamate levels due to enhanced synthesis and reduced reuptake may induce neuronal damage by abnormal activation of extrasynaptic N-methyl d-aspartate receptor (NMDAR) subunits. NMDAR is the key factor that mediates the disturbances in intracellular calcium homeostasis, mitochondrial dysfunction and generation of reactive oxygen species in NPs exposed neurons. While some NPs cause neuronal death by inducing NMDARs, others may be neurotoxic through the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors or protect the neurons via blocking NMDARs. However, mechanisms of dual effects of NPs, neurotoxicity or neuroprotection are not precisely known. Some NPs present neuroprotective effect either by selectively inhibiting extrasynaptic subunit of NMDARs or by attenuating oxidative stress. NPs-related proinflammatory activation of microglia contributes to the dysfunction and cytotoxicity in neurons. Therefore, investigation of the interaction of NPs with the neuronal signaling molecules and neuronal receptors is necessary for the better understanding of the neurotoxicity or neurosafety of nanomaterials.

The effect of adipocyte-macrophage crosstalk in obesity-related breast cancer

Adipose tissue is the primary source of many pro-inflammatory cytokines in obesity. Macrophage numbers and pro-inflammatory gene expression are positively associated with adipocyte size. Free fatty acid and tumor necrosis factor-α involve in a vicious cycle between adipocytes and macrophages aggravating inflammatory changes. Thereby, M1 macrophages form a characteristic 'crown-like structure (CLS)' around necrotic adipocytes in obese adipose tissue. In obese women, CLSs of breast adipose tissue are responsible for both increase in local aromatase activity and aggressive behavior of breast cancer cells. Interlinked molecular mechanisms between adipocyte-macrophage-breast cancer cells in obesity involve seven consecutive processes: Excessive release of adipocyte- and macrophage-derived inflammatory cytokines, TSC1-TSC2 complex-mTOR crosstalk, insulin resistance, endoplasmic reticulum (ER) stress and excessive oxidative stress generation, uncoupled respiration and hypoxia, SIRT1 controversy, the increased levels of aromatase activity and estrogen production. Considering elevated risks of estrogen receptor (E2R)-positive postmenopausal breast cancer growth in obesity, adipocyte-macrophage crosstalk is important in the aforementioned issues. Increased mTORC1 signaling in obesity ensures the strong activation of oncogenic signaling in E2Rα-positive breast cancer cells. Since insulin and insulin-like growth factors have been identified as tumor promoters, hyperinsulinemia is an independent risk factor for poor prognosis in breast cancer despite peripheral insulin resistance. The unpredictable effects of adipocyte-derived leptin-estrogen-macrophage axis, and sirtuin 1 (SIRT1)-adipose-resident macrophage axis in obese postmenopausal patients with breast cancer are unresolved mechanistic gaps in the molecular links between the tumor growth and adipocytokines.

DNA damage checkpoint response to aflatoxin B1

Although most countries regulate the aflatoxin levels in food by legislations, high amounts of aflatoxin B1 (AFB1)-DNA adducts can still be detected in normal and tumorous tissue obtained from cancer patients. AFB1 cannot directly interact with DNA unless it is biotransformed to AFB1-8, 9-epoxide via cytochrome p450 enzymes. This metabolite spontaneously and irreversibly attaches to guanine residues to generate highly mutagenic DNA adducts. AFB1-induced mutation of ATM kinase results in the deterioration of the cell cycle checkpoint activation at the G2/M checkpoint site. Genomic instability and increased cancer risk due to A-T mutation is the result of diminished repair of DNA double strand breaks. The major point mutation caused by AFB1 is G-to-T transversion that is related with the high frequency of p53 mutation. Majority of AFB1 associated hepatocellular cancer cases carry TP53 mutant DNA, which is an indicator of AFB1 exposure, as well as hepatocellular cancer risk.

Perioperative Mortality Prediction Using Possum in Patients with Gastrointestinal Tumors: Do Immunological Variables Affect Individual Predictive Mortality Risk?

The aim of this study was to evaluate whether the addition of immunological variables to the Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) scoring system improves the predictability of postoperative mortality. One hundred and thirty-two consecutive patients who underwent moderate, major or major-plus elective surgical interventions for gastrointestinal tumors were scored using the POSSUM mortality risk analysis. Patients were placed in one of the two groups based on their POSSUM mortality rates which were either lower or higher than 5%. An additional 26 pre-operative and post-operative metabolic and immunological variables were measured and mortality-dependent variables were selected. Regression analysis with backward elimination of twelve pre-operative and post-operative variables correlating with POSSUM score revealed that post-operative neopterin, IL-6 and albumin were significantly dependent on the predicted mortality rates. According to these selected variables, the number of patients with a POSSUM predicted mortality rate higher than 5% increased from 64 to 88, but the percentage of the mean mortality decreased. Statistical differences between the original POSSUM and modified scoring system was highly significant (p<0.0001). The sensitivity and specificity of the modified scoring system was calculated to be 52.9% and 87.5%, respectively.

The impact of immunotoxicity in evaluation of the nanomaterials safety

Nanomedicinal products (NMPs), due to their unique properties, are extensively investigated for their biomedical and pharmaceutical applications. Apart from being carriers of certain drugs, nanoparticles can also interact with both the innate and adaptive immune systems, thus eliciting immune responses. Following administration, their discrete physicochemical properties make each NMP act differently in the organism. Actually, the toxic effects of NMPs, in terms of specific end points, do not necessarily depend on the specific group or structural type of the particle. Furthermore, the nanoformulation may change the pharmacokinetic/toxicokinetic profile of the drug. Unveiling the structure–activity relationship of NMPs would help to clarify their immunomodulatory effects. Therefore, in addition to the current regulatory immunotoxicity testing strategies, development and regulatory approval of nano-sized pharmaceuticals still need to be discussed in order to identify potential gaps in the safety assessment.

Influence of Surgical Trauma on Neopterin Concentrations in Gastric Carcinoma Patients

Aims and background

Impairment of immune surveillance in the immediate postoperative period may accelerate the growth of tumor cells that remain despite radical resection in advanced cases. The present study was undertaken to evaluate the impact of major surgical trauma on host cellular immunity of gastric carcinoma cases.

Methods and study design

Sixty-eight consecutive patients with gastric carcinoma were divided into three subgroups according to the classification of the American Joint Committee on Cancer Staging, and they underwent surgery with a curative intent. Thirty-eight cancer-free patients served as controls, and they underwent surgical management for benign diseases. Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) risk adjustment system was used to estimate the operative and physiological scores of patients. Plasma cortisol, serum interleukin-6 and high-sensitive C-reactive protein levels were determined in order to assess the severity of trauma-related inflammatory response. The frequency of increased neopterin concentrations of cancer patients was estimated by comparison with the average values of controls.

Results

Response of interleukin-6 to surgery was closely related with the postoperative cortisol of cancer patients, but not correlated with neopterin and high-sensitive C-reactive protein levels. Although the extent of tumor invasion might have gradually decreased the macrophage response to surgical trauma, the overall increase in postoperative neopterin levels of cancer cases was highly significant. However, maximal frequency of increased neopterin concentration was obtained in advanced group.

Conclusions

Macrophages might recognize the traumatic challenges in every stage of gastric cancer. Increasing individual neopterin concentration was not solely specific for tumor growth, but it was partially predictive of immune competence even in advanced cases.

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.

Mechanistic understanding of nanoparticles' interactions with extracellular matrix: the cell and immune system

Extracellular matrix (ECM) is an extraordinarily complex and unique meshwork composed of structural proteins and glycosaminoglycans. The ECM provides essential physical scaffolding for the cellular constituents, as well as contributes to crucial biochemical signaling. Importantly, ECM is an indispensable part of all biological barriers and substantially modulates the interchange of the nanotechnology products through these barriers. The interactions of the ECM with nanoparticles (NPs) depend on the morphological characteristics of intercellular matrix and on the physical characteristics of the NPs and may be either deleterious or beneficial. Importantly, an altered expression of ECM molecules ultimately affects all biological processes including inflammation. This review critically discusses the specific behavior of NPs that are within the ECM domain, and passing through the biological barriers. Furthermore, regenerative and toxicological aspects of nanomaterials are debated in terms of the immune cells-NPs interactions.

Glutamate‑mediated effects of caffeine and interferon‑γ on mercury-induced toxicity

The molecular mechanisms mediating mercury‑induced neurotoxicity are not yet completely understood. Thus, the aim of this study was to investigate whether the severity of MeHg‑ and HgCl2‑mediated cytotoxicity to SH‑SY5Y human dopaminergic neurons can be attenuated by regulating glutamate‑mediated signal‑transmission through caffeine and interferon‑γ (IFN‑γ). The SH‑SY5Y cells were exposed to 1, 2 and 5 µM of either MeHgCl2 or HgCl2 in the presence or absence of L‑glutamine. 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 IFN‑γ‑ and glutamate‑stimulated SH‑SY5Y cells. Following exposure to mercury, the concentration‑dependent decrease in mitochondrial metabolic activity inversely correlated with oxidative stress intensity. MeHg was more toxic than HgCl2. Mercury‑induced neuronal death was dependent on glutamate‑mediated excitotoxicity. Caffeine reduced the mercury‑induced oxidative stress in glutamine-containing medium. IFN‑γ treatment decreased cell viability and increased oxidative stress in glutamine‑free medium, despite caffeine supplementation. Although caffeine exerted a protective effect against MeHg-induced toxicity with glutamate transmission, under co‑stimulation with glutamine and IFN‑γ, caffeine decreased the MeHg‑induced average oxidative stress only by half. Thereby, our data indicate that the IFN‑γ stimulation of mercury‑exposed dopaminergic neurons in neuroinflammatory diseases may diminish the neuroprotective effects of caffeine.

Oral application of carbon nanofibers in rats increases blood concentration of IL6 and IL10 and decreases locomotor activity

Carbon nanofibers (CNF) are versatile nanomaterials that are widely used in various fields of science and technology. As a consequence, animals as well as humans may be exposed to such compounds via different routes. We hypothesized that oral intake of CNF will lead to an inflammatory reaction and consequently induce behavioral impairments. To address this issue, rats were fed with 500mg/kgCNF for 14days and their locomotor activity, emotional status and cognition were quantified by testing the animals in an open field set-up, elevated plus maze and in the universal problem solving box which provides information about motivation and cognition. The behavioral tests were performed 3 times within 10days. At the end of the experiment, blood samples were collected and the plasma concentrations of IL-6, IL-8, IL-1β, IL-10 and IL-18 were measured. Our results demonstrated an inflammatory reaction determined by a significantly elevated IL-6 concentration. This, however, was counteracted by an even more pronounced increase in IL-10. The behavioral effects were restricted mainly to a decrease in locomotor activity which was significant in the open field test, as well as the elevated plus maze. Other parameters indicative of cognitive performance were not influenced and also the emotional status was largely unaffected. In conclusion, our results revealed that oral intake of 500mg/kgCNF induced some adverse effects, which, however, can be still partially compensated by the organism.

Protein bio-corona: critical issue in immune nanotoxicology

With the expansion of the nanomedicine field, the knowledge focusing on the behavior of nanoparticles in the biological milieu has rapidly escalated. Upon introduction to a complex biological system, nanomaterials dynamically interact with all the encountered biomolecules and form the protein "bio-corona." The decoration with these surface biomolecules endows nanoparticles with new properties. The present review will address updates of the protein bio-corona characteristics as influenced by nanoparticle's physicochemical properties and by the particularities of the encountered biological milieu. Undeniably, bio-corona generation influences the efficacy of the nanodrug and guides the actions of innate and adaptive immunity. Exploiting the dynamic process of protein bio-corona development in combination with the new engineered horizons of drugs linked to nanoparticles could lead to innovative functional nanotherapies. Therefore, bio-medical nanotechnologies should focus on the interactions of nanoparticles with the immune system for both safety and efficacy reasons.

Basophil mediated pro-allergic inflammation in vehicle-emitted particles exposure

Despite of the fact that engine manufacturers develop a new technology to reduce exhaust emissions, insufficient attention given to particulate emissions. However, diesel exhaust particles are a major source of air-borne pollution, contain vast amount of polycyclic aromatic hydrocarbons (PAHs) and may have deleterious effects on the immune system, resulting in the induction and enhancement of pro-allergic processes. In the current study, vehicle emitted particles (VEP) from 2 different types of cars (diesel - D and gasoline - G) and locomotive (L) were collected. Overall, 129 four-week-old, male SPF-class Kunming mice were subcutaneously instilled with either low dose 100, 250 or high dose, 500mg/kg VEP and 15 mice were assigned as control group. The systemic toxicity was evaluated and alterations in the percentages of the CD3, CD4, CD8, CD16, CD25 expressing cells, basophils, eosinophils and neutrophils were determined. Basophil percentages were inversely associated with the PAH content of the VEPs, however basophil sensitization was more important than cell count in VEP exposure. Thus, the effects of VEP-PAHs emerge with the activation of basophils in an allergen independent fashion. Despite the increased percentage of CD4+ T cells, a sharp decrease in basophil counts at 500mg/kg of VEP indicates a decreased inhibitory effect of CD16+ monocytes on the proliferation of CD4+ T cell and suppressed polarization into a Th2 phenotype. Therefore, although the restrictions for vehicles emissions differ between countries, follow up studies and strict regulations are needed.

The Interactions Between Kynurenine, Folate, Methionine and Pteridine Pathways in Obesity

Obesity activates both innate and adaptive immune responses in adipose tissue. Elevated levels of eosinophils with depression of monocyte and neutrophil indicate the deficiencies in the immune system of morbidly obese individuals. Actually, adipose tissue macrophages are functional antigen-presenting cells that promote the proliferation of interferon-gamma (IFN-gamma)-producing CD4+ T cells in adipose tissue of obese subjects. Eventually, diet-induced obesity is associated with the loss of tissue homeostasis and development of type 1 inflammatory responses in visceral adipose tissue. Activity of inducible indoleamine 2,3-dioxygenase-1 (IDO-1) plays a major role under pro-inflammatory, IFN-gamma dominated settings. One of the two rate-limiting enzymes which can metabolize tryptophan to kynurenine is IDO-1. Tumor necrosis factor-alpha (TNF-alpha) correlates with IDO-1 in adipose compartments. Actually, IDO-1-mediated tryptophan catabolism due to chronic immune activation is the cause of reduced tryptophan plasma levels and be considered as the driving force for food intake in morbidly obese patients. Thus, decrease in plasma tryptophan levels and subsequent reduction in serotonin (5-HT) production provokes satiety dysregulation that leads to increased caloric uptake and obesity. However, after bariatric surgery, weight reduction does not lead to normalization of IDO-1 activity. Furthermore, there is a connection between arginine and tryptophan metabolic pathways in the generation of reactive nitrogen intermediates. Hence, abdominal obesity is associated with vascular endothelial dysfunction and reduced nitric oxide (NO) availability. IFN-gamma-induced activation of the inducible nitric oxide synthase (iNOS) and dissociation of endothelial adenosine monophosphate activated protein kinase (AMPK)- phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt)- endothelial NO synthase (eNOS) pathway enhances oxidative stress production secondary to high-fat diet. Thus, reduced endothelial NO availability correlates with the increase in plasma non-esterified fatty acids and triglycerides levels. Additionally, in obese patients, folate-deficiency leads to hyperhomocysteinemia. Folic acid confers protection against hyperhomocysteinemia-induced oxidative stress.

Simulating real-life exposures to uncover possible risks to human health: A proposed consensus for a novel methodological approach

In real life, consumers are exposed to complex mixtures of chemicals via food, water and commercial products consumption. Since risk assessment usually focuses on individual compounds, the current regulatory approach doesn't assess the overall risk of chemicals present in a mixture. This study will evaluate the cumulative toxicity of mixtures of different classes of pesticides and mixtures of different classes of pesticides together with food additives (FAs) and common consumer product chemicals using realistic doses after long-term exposure. Groups of Sprague Dawley (CD-SD) rats (20 males and 20 females) will be treated with mixtures of pesticides or mixtures of pesticides together with FAs and common consumer product chemicals in 0.0, 0.25 × acceptable daily intake (ADI)/tolerable daily intake (TDI), ADI/TDI and 5 × ADI/TDI doses for 104 weeks. All animals will be examined every day for signs of morbidity and mortality. Clinical chemistry hematological parameters, serum hormone levels, biomarkers of oxidative stress, cardiotoxicity, genotoxicity, urinalysis and echocardiographic tests will be assessed periodically at 6 month intervals. At 3-month intervals, ophthalmological examination, test for sensory reactivity to different types of stimuli, together with assessment of learning abilities and memory performance of the adult and ageing animals will be conducted. After 24 months, animals will be necropsied, and internal organs will be histopathologically examined. If the hypothesis of an increased risk or a new hazard not currently identified from cumulative exposure to multiple chemicals was observed, this will provide further information to public authorities and research communities supporting the need of replacing current single-compound risk assessment by a more robust cumulative risk assessment paradigm.

Circulating IL-6 and neopterin concentrations link cell-mediated immunity and tumor stage in patients with gastro-intestinal adenocarcinoma: relevance to the pituitary-adrenal axis and pituitary-thyroid axis

Although cortisol is a powerful modulator of the immune system and inhibits production of pro-inflammatory cytokines, adrenocorticotropic hormone (ACTH) levels do not correspond to the chronically elevated concentrations of cortisol in cancer patients. Thyroid stimulating hormone (TSH) has been shown to have an effect on immunological functions. Actually it is not known whether cortisol, TSH and IL-6 have an effect on tumor progression via modulation of cell mediated immunity in patients with gastrointestinal carcinoma. Sixty-seven gastrointestinal cancer patients and 42 cancer-free subjects with cholelithiasis as the control group, were included in the study. Serum ACTH, cortisol, TSH, thyroid hormones, IL-6, IL-10 and neopterin levels were measured. Diagnosis and pathological staging were confirmed by surgical intervention. Cortisol levels were correlated with IL-6 in cancer patients. In addition to elevated neopterin values, linear regression analysis revealed that serum neopterin was associated more strongly with the increase of cortisol rather than IL-6 levels in advanced stage carcinoma. Furthermore, neopterin also correlated with IL-6, IL-10, cortisol and TSH levels in advanced carcinoma cases. These data indicated that cortisol, IL-6 and neopterin values of cancer patients were influenced by the tumor presence and progression.

Relationship between indoleamine 2,3-dioxygenase activity and lymphatic invasion propensity of colorectal carcinoma

AIM

To evaluate whether serum and tumor indoleamine 2,3-dioxygenase activities can predict lymphatic invasion (LI) or lymph node metastasis in colorectal carcinoma.

METHODS

The study group consisted of 44 colorectal carcinoma patients. The patients were re-grouped according to the presence or absence of LI and lymph node metastasis. Forty-three cancer-free subjects without any metabolic disturbances were included into the control group. Serum neopterin was measured by enzyme linked immunosorbent assay. Urinary neopterin and biopterin, serum tryptophan (Trp) and kynurenine (Kyn) concentrations of all patients were determined by high performance liquid chromatography. Kyn/Trp was calculated and its correlation with serum neopterin was determined to estimate the serum indoleamine 2,3-dioxygenase activity. Tissue sections from the studied tumors were re-examined histopathologically and were stained by immunohistochemistry with indoleamine-2,3-dioxygenase antibodies.

RESULTS

Neither serum nor urinary neopterin was significantly different between the patient and control groups (both P > 0.05). However, colorectal carcinoma patients showed a significant positive correlation between the serum neopterin levels and Kyn/Trp (r = 0.450, P < 0.01). Urinary biopterin was significantly higher in cancer cases (P < 0.05). Serum Kyn/Trp was significantly higher in colorectal carcinoma patients (P < 0.01). Lymphatic invasion was present in 23 of 44 patients, of which only 12 patients had lymph node metastasis. Eleven patients with LI had no lymph node metastasis. Indoleamine-2,3-dioxygenase intensity score was significantly higher in LI positive cancer group (44.56% ± 6.11%) than negative colorectal cancer patients (24.04% ± 6.90%), (P < 0.05). Indoleamine 2,3-dioxygenase expression correlated both with the presence of LI and lymph node metastasis (P < 0.01 and P < 0.05, respectively). A significant difference between the accuracy of diagnosis by using either total indoleamine-2,3-dioxygenase immunostaining score or of lymph node metastasis was found during the evaluation of cancer patients.

CONCLUSION

Indoleamine-2,3-dioxygenase expression may predict the presence of unrecognized LI and lymph node metastasis and may be included in the histopathological evaluation of colorectal carcinoma cases.

The impact of multi-walled carbon nanotubes with different amount of metallic impurities on immunometabolic parameters in healthy volunteers

The impact of two types of multi-walled carbon nanotubes (MWCNTs) (12-14 nm) with different content of metallic impurities (purified and unpurified nanotubes) on peroxidation processes, the status of immune cells in healthy volunteers and gene expression combined to pathway analysis was studied in vitro. From the study it was shown that the main mechanism of action for both types of MWCNTs is induction of oxidative stress, the intensity of which is directly related to the amount of metallic impurities. Unpurified MWCNTs produced twice as high levels of oxidation than the purified CNTs inducing thus more intense mitochondrial dysfunction. All the above were also verified by gene expression analysis of 2 different human cellular cultures (lung epithelium and keratinoma cells) and the respective pathway analysis; modulation of genes activating the NFkB pathway is associated to inflammatory responses. This may cause a perturbation in the IL-6 signaling pathway in order to regulate inflammatory processes and compensate for apoptotic changes. A plausible hypothesis for the immunological effects observed in vivo, are considered as the result of the synergistic effect of systemic (mediated by cells of the routes of exposure) and local inflammation (blood cells).

Helicobacter pylori and serum kynurenine-tryptophan ratio in patients with colorectal cancer

AIM: To evaluate how Helicobacter pylori (H. pylori) is able to evade the immune response and whether it enhances systemic immune tolerance against colorectal cancer.

METHODS: This prospective randomized study involved 97 consecutive colorectal cancer patients and 108 cancer-free patients with extra-digestive diseases. Colorectal cancer and cancer-free patients were assigned into subgroups according to H. pylori IgG seropositivity. Exposure to H. pylori was determined by IgG seropositivity which was detected by enzyme linked immunoassay (ELISA). Serum neopterin levels were measured by ELISA. Serum tryptophan, kynurenine, and urinary biopterin concentrations were measured by high performance liquid chromatography. Serum nitrite levels were detected spectrophotometrically. Serum indoleamine 2,3-dioxygenase activity was estimated by the kynurenine to tryptophan ratio and by assessing the correlation between serum neopterin concentrations and the kynurenine to tryptophan ratio. The frequencies of increased serum kynurenine to tryptophan ratio of H. pylori seronegative and seropositive colorectal cancer subgroups were estimated by comparing them with the average kynurenine to tryptophan ratio of H. pylori seronegative tumor-free patients.

RESULTS: Compared with respective controls, in both H. pylori seronegative and seropositive colorectal cancer patients, while serum tryptophan levels were decreased (controls vs patients; seronegative: 20.37 ± 0.89 μmol/L vs 15.71 ± 1.16 μmol/L, P < 0.05; seropositive: 20.71 ± 0.81 μmol/L vs 14.97 ± 0.79 μmol/L, P < 0.01) the kynurenine to tryptophan ratio was significantly increased (controls vs patients; seronegative: 52.85 ± 11.85 μmol/mmol vs 78.91 ± 8.68 μmol/mmol, P < 0.01, seropositive: 47.31 ± 5.93 μmol/mmol vs 109.65 ± 11.50 μmol/mmol, P < 0.01). Neopterin concentrations in cancer patients were significantly elevated compared with controls (P < 0.05). There was a significant correlation between serum neopterin levels and kynurenine/tryptophan in control and colorectal cancer patients groups (r_s = 0.494, P = 0.0001 and r_s = 0.293, P = 0.004, respectively). Serum nitrite levels of H. pylori seropositive cancer cases were significantly decreased compared with seropositive controls (controls vs patients; 26.04 ± 2.39 μmol/L vs 20.41 ± 1.48 μmol/L, P < 0.05) The decrease in the nitrite levels of H. pylori seropositive cancer patients may be attributed to excessive formation of peroxynitrite and other reactive nitrogen species.

CONCLUSION: A significantly high kynurenine/tryptophan suggested that H. pylori may support the immune tolerance leading to cancer development, even without an apparent upper gastrointestinal tract disease.

Effect of N-acetyl cysteine, Neopterin and Dexamethasone on the Viability of Titanium dioxide Nanoparticles Exposed Cell Lines

Titanium is extensively used for a wide range of implanted medical devices due to its advantageous combination of physico-chemical and biological properties. Nano-size titanium dioxide (TiO2) is also used in a variety of consumer products. Such widespread use and its potential entry through various routes of the body suggest that TiO2 could pose an exposure risk to humans. Nano-size particles (NP) enter systemic circulation, accumulate and damage tissues that are especially sensitive to oxidative stress. We hypothesized that TiO2 NPs can exert diverse cytotoxic effects on various human cell type especially neural cell lines. In order to test our hypothesis, putative cytotoxic effects of oxidative stress due to TiO2 NPs exposure on IM9, U937 and SHSY5Y (human neuroblastoma cells) were investigated in N-acetyl cysteine (NAC), neopterin and dexamethasone pre-treated cell cultures. IM9, U937 and SHSY5Y cells were exposed to ten different concentrations of 25 and 10 nm diameter TiO2 NPs in three different time periods before and after treatment with NAC, neopterin and dexamethasone. To determine toxicity levels of NPs, cell viability was estimated by MTT test. Concentration of cells was assessed by counting trypan blue stained cells with a heamo-cytometer. Toxicity of 25nm TiO2 particles was significantly increased (p<0.05) by adding fetal bovine serum (FBS) in SHYS5Y and U937 cell lines culture medium. Concentrationdependent toxicity of 10 nm TiO2 NP was weakly increased by adding FBS to SHYS5Y, IM9 and U937 cell culture media. NAC pre-treatment provided significant protection for only SHYS5Y cell exposed to 25 nm and 10 nm of TiO2 NPs after a 24-hour incubation period. Neopterin pre-treated SHYS5Y cells displayed significant increases in viability after 24-hour exposure to 10 nm and 25 nm TiO2 NPs. While exposure of dexamethasone pre-treated U937 cells to 25 nm of TiO2 NPs induced a significant increase in cell survival at only 100 mg/ml particle concentration, increase in viability of SHYS5Y cells were observed at all concentrations against 10 nm particle challenge. Our study demonstrated that exposure of SHYS5Y to TiO2 NPs for 24 hours regularly induced reduction of cell viability. We also found similar dose-related effects of TiO2 NPs in reducing cell survival in IM9 cells. This study clearly indicated that FBS is an effective dispersing agent for TiO2 NPs and increased TiO2 toxicity in all cell lines. NAC and neopterin significantly protected the SHYS5Y cell against the putative cytotoxic effects of TiO2 NPs.

Exposure to Helicobacter pylori and Serum Kynurenine to Tryptophan Ratio in Patients with Gastric Cancer

In Helicobacter pylori seropositive individuals, the subsequent risk of non-cardia gastric cancer development is frequently attributed to the infection agent. Although the link between inflammation and gastric cancer is formally recognized, the molecular basis of evading mechanisms of Helicobacter pylori from host immune system remains unclear.

The aim of this study was to determine the effect of systemic factors in gastric cancer patients such as serum kynurenine to tryptophan ratios, neopterin, nitric oxide and urinary biopterin levels which may sustain the persistence of Helicobacter pylori seropositivity. This prospective randomized study involved 95 adults with gastric cancer and 108 cancer free patients with extradigestive diseases. Each group was assigned into two subgroups according to Helicobacter pylori IgG seropositivity. Exposure to Helicobacter pylori was detected by serum IgG test (ELISA). Serum tryptophan, kynurenine, neopterin and nitrite concentrations were measured. In simultaneous urinary samples, neopterin, biopterin, and creatinine levels were assayed. Significant decreases were found in serum tryptophan levels of both Helicobacter pylori seronegative and seropositive gastric cancer patients versus controls without malignant disease. However, marked increase in kynurenine/tryptophan was observed only in Helicobacter pylori seropositive cancer patients. Highly significant correlation between the serum neopterin and kynurenine/tryptophan indicated interferon gamma stimulated tryptophan degradation. Decrease in serum nitrite levels, and a parallel increase in urinary biopterin concentrations in Helicobacter pylori seropositive cancer cases might result from the excessive nitric oxide consumption due to reactive oxygen radical overproduction. Significantly higher kynurenine to tryptophan ratio and its correlation with increased neopterin levels suggested a role of tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) and that persistence of Helicobacter pylori seropositivity might participate in enhanced immune tolerance of cancer patients.

Neopterin Profile to Evaluate the Effectiveness of Treatment in Aggressive Periodontitis

Periodontal disease results from the interaction of the host defence mechanisms with the microbial dental plaque. Analysis of gingival crevicular Huid (GCF) provides a non-invasive means of evaluating the role of the host response in periodontal disease. Based on our previous study, demonstrating increased levels of neopterin in GCF and saliva from patients with aggressive periodontitis (AgP), the aim of this study was to evaluate the effect of periodontal treatment on the levels of neopterin in GCF, saliva and urine of patients with AgP.

Pre-treatment values of neopterin in GCF were 4.04 ± 0.86 nmol/ml for the AgP group (n=8) and 2.68 ± 0.90 nmol/ml fyr the control group (n=8; difference not significant). After periodontal treatment, the level of ncoptei in was found 2.38 ± 0.72 nmol/ml in the patient group which did not differ f r om pre-treatment levels. The salivary neopterin concentration was higher in both AgP groups (14.14 ± 2.85 nmol/1 and 8.02 ± 3.12 nmol/1, before and after periodontal treatment) than in controls (2.58 ± 0.3 nmol/1; both p<0.05). No significant difference in salivary neopterin level was observed in patients before and after periodontal treatment.

Concentrations of urine neopterin in patients before treatment were 188.5 ± 30.98 μηιοί neopterin/mol creatinine and 168.1 + 20.21 μηιοί in controls (difference not significant). Following periodontal treatment, the urinary neopterin levels (310.1 ± 39.82 μηιοί neopterin/mol creatinine) were higher when compared to the baseline levels and to controls (p<0.05).

Our results suggest that neopterin in saliva and GCF might be associated with the periodontal diseases process.

Oxidative stress and tryptophan degradation pattern of acute Toxoplasma gondii infection in mice

Toxoplasma gondii is a very common obligate single-cell protozoan parasite which induces overproduction of interferon (IFN)-gamma and of other proinflammatory cytokines. Although immunomodulatory role of IFN-gamma favors tryptophan (Trp) degradation via indoleamine-2,3-dioxygenase (IDO) activity and is related with nitric oxide (NO) synthesis, the mechanism of antitoxoplasma activity is complex. In order to characterize the Trp degradation pattern during the acute T. gondii infection, serum Trp, kynurenine (Kyn), and urinary biopterin levels of mice were measured. The possible oxidative status was evaluated by the liver, spleen, brain, and serum malondialdehyde (MDA) and NO levels. Increased free radical toxicity may cause elevation in tissue MDA in T. gondii-infected mice, while unchanged serum MDA might indicate the increased oxidative stress due to T. gondii infection restricted to intracellular area. Elevated serum NO most probably might be due to the formation of reactive nitrogen radicals. The Kyn/Trp ratio was higher in T. gondii-infected mice compared to healthy animals (p < 0.05); however, it was not correlated with urinary biopterin. These results suggested that Trp degradation might be promoted by a pathway other than IDO during T. gondii infection and the reduction of Trp concentration favors the local immunosuppression and systemic tolerance.

Association between ABCB1 gene polymorphisms and fentanyl's adverse effects in Turkish patients undergoing spinal anesthesia

The ATP-binding cassette transporter (ABCB1) gene product, P-glycoprotein plays an important role in the prevention of intracellular accumulation of potentially toxic substances and metabolites in various tissues. Single nucleotide polymorphisms in this gene are claimed to be correlated with changes in the function of P-glycoprotein. There is evidence that fentanyl, may be a substrate for P-glycoprotein. The aim of the study was to assess whether an association exists between ABCB1 gene polymorphism and early respiratory and sedative adverse effects of intravenous fentanyl in Turkish patients who underwent spinal anesthesia In all 83 unrelated Turkish patients were enrolled in this study. In this study, spinal anesthesia was provided and a single dose of intravenous fentanyl (2.5μg.kg(-1)) at the beginning of surgery was used as a sedative agent. Bispectral index, respiration rate and peripheral oxygen saturation were measured continuously and recorded throughout the study. The allele and genotype frequencies were similar to previous data from Turkish population. Respiratory rate (RR) and SpO(2) parameters of the patients did not show any significant difference according to the genotype distribution for C1236T and C3435T SNPs. Fentanyl-induced decrease in respiration rate was most remarkable at 15min (23%) in CC genotype of C1236T, whereas in TT genotype of C3435T (18%) polymorphism. SpO(2) parameters in allele distribution were also not significant among the groups (p=0.374, p=0.985, respectively). For the C1236T polymorphism, patients carrying T allele showed a significant decrease in pH, and a significant increase in pCO(2) (p<0.001). ABCB1 polymorphisms did not seem to have a significant effect on sedation and respiratory depression caused by intravenous fentanyl in spinal anesthesia in Turkish patients.

Effect of butylated hydroxytoluene (E321) pretreatment versus L-arginine on liver injury after sub-lethal dose of endotoxin administration

Aim of this study was to compare the effects of L-arginine (L-arg) and food-antioxidant butylated hydroxytoluene (BHT) against oxidative stress of Escherichia coli endotoxin (LPS) in liver. Ninety Wistar albino rats were assigned in three groups. Rats received one of the following pre-treatment previous to 5mg/kg LPS intraperitoneally: saline, L-arg (NO donor, 100mg/kg) or BHT (250 mg/kg/day), for 3 days. At second, fourth and sixth hours, plasma nitrite-plus-nitrate, circulating liver enzymes, glutathione levels, superoxide dismutase, glutathione peroxidase activities were measured. The most remarkable liver injury was evident in BHT pre-treated animals at all time points compared to L-arg pre-treated rats. While BHT enhanced superoxide dismutase activities following LPS, glutathione decreased simultaneously compared to L-arg group. Although the risk associated with the use of BHT alone in subthreshold doses appeared to be low, higher risk of liver toxicity should be considered when over-consuming this food additive in endotoxemic settings.

Dual function of nitric oxide in carcinogenesis, reappraisal

Nitric oxide, a unique signalling molecule, is synthesized from L-arginine by a family of isoenzymes called nitric oxide synthase. Function of nitric oxide largely depends on the concentrations of surrounding free radicals and redox state. The local concentration of the nitric oxide defines its anti- or protumorigenic function by interacting with DNA or DNA repair enzymes and tumor suppressor gene, p53, as well. Indoleamine 2,3-dioxygenase activity is induced by interferon-gamma in many human cell types or cancer cells. Indoleamine 2,3- dioxygenase depletes locally available L- tryptophan producing cytotoxic metabolite kynurenine. Nitric oxide regulates the indoleamine 2,3-dioxygenase activity in a dose dependent-manner leading to either enhanced immune response or immune tolerance against tumor tissue. Additionally, the overproduction of nitric oxide may also trigger the cyclooxygenase-lipooxygenase pathways. Nitric oxide synthase expression correlates with cyclooxygenase-2 expression in cancer cells. On the other hand, tetrahydrobiopterin acts as the cofactor for nitric oxide synthase and stabilizes nitric oxide synthase dimers. However, tetrahydrobiopterin acts biphasically; under limited concentrations of tetrahydrobiopterin, nitric oxide generates superoxide radicals. Thus the dual action of nitric oxide and its interaction with the related compounds are of concern for their contribution in the development of carcinogenesis. In this review critical links between the nitric oxide and chronic inflammation associated carcinogenesis are summarized.

Increased tryptophan degradation in patients with bronchus carcinoma

Expression of tryptophan-degrading enzyme indoleamine (2,3)-dioxygenase in tumour tissue is proposed to represent an important tumour immunoescape mechanism. To further investigate the potential role of activated indoleamine (2,3)-dioxygenase in bronchus carcinoma, we examined serum tryptophan and kynurenine concentrations in nine patients with small cell lung cancer and in 27 patients with non-small cell lung cancer. Tryptophan metabolic changes were compared with markers of inflammation and immune activation namely C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and neopterin. Compared with controls, patients presented with lower tryptophan concentrations (P < 0.01) and with higher serum kynurenine to tryptophan ratios (P < 0.01), an index of tryptophan degradation. Also ESR and CRP and neopterin concentrations were increased in the patients (all P < 0.001), and there was a weak correlation between kynurenine to tryptophan ratio and ESR, CRP and neopterin concentrations. We conclude that in the majority of patients with non-small cell lung cancer and small cell lung cancer, enhanced tryptophan degradation can be observed. It seems to relate to an inflammatory response and may reflect activation of indoleamine (2,3)-dioxygenase at the tumour site. The capacity of the tumour to escape normal host immune defence may be influenced by tryptophan degradation. Results of this pilot study deserve further confirmation.