Impaired Nitric Oxide Synthetase Activity in Primary Ciliary Dyskinesia-Data-Driven Hypothesis

Low nasal nitric oxide (nNO) is a typical feature of Primary Ciliary Dyskinesia (PCD). nNO is part of the PCD diagnostic algorithm due to its discriminative power against other lung diseases, such as cystic fibrosis (CF). However, the underlying pathomechanisms are elusive. To better understand NO dysregulation in PCD, the L-arginine/NO (Arg/NO) pathway in patients with PCD (pwPCD) and CF (pwCF) and in healthy control (HC) subjects was investigated. In a prospective, controlled study, we measured in 24 pwPCD, 25 age-matched pwCF, and 14 HC the concentrations of the NO precursors Arg and homoarginine (hArg), the arginase metabolite ornithine (Orn), the NO inhibitor asymmetric dimethylarginine (ADMA), and the major NO metabolites (nitrate, nitrite) in sputum, plasma, and urine using validated methods. In comparison to HC, the sputum contents (in µmol/mg) of L-Arg (PCD 18.43 vs. CF 329.46 vs. HC 9.86, p < 0.001) and of ADMA (PCD 0.055 vs. CF 0.015 vs. HC 0.010, p < 0.001) were higher. In contrast, the sputum contents (in µmol/mg) of nitrate and nitrite were lower in PCD compared to HC (nitrite 4.54 vs. 9.26, p = 0.023; nitrate 12.86 vs. 40.33, p = 0.008), but higher in CF (nitrite 16.28, p < 0.001; nitrate 56.83, p = 0.002). The metabolite concentrations in urine and plasma were similar in all groups. The results of our study indicate that PCD, unlike CF, is associated with impaired NO synthesis in the lung, presumably due to mechano-chemical uncoupling.

Inhibition of SOS Response by Nitric Oxide Donors in Escherichia coli Blocks Toxin Production and Hypermutation

Background

Previous reports have differed as to whether nitric oxide inhibits or stimulates the SOS response, a bacterial stress response that is often triggered by DNA damage. The SOS response is an important regulator of production of Shiga toxins (Stx) in Shiga-toxigenic E. coli (STEC). In addition, the SOS response is accompanied by hypermutation, which can lead to de novo emergence of antibiotic resistance. We studied these effects in vitro as well as in vivo.

Results

Nitric oxide donors inhibited induction of the SOS response by classical inducers such as mitomycin C, ciprofloxacin, and zidovudine, as measured by assays for E. coli RecA. Nitric oxide donors also inhibited Stx toxin protein production as well as stx2 RNA in vitro and in vivo. In vivo experiments were performed with ligated ileal segments in the rabbit using a 20 h infection. The NO donor S-nitroso-acetylpenicillamine (SNAP) reduced hypermutation in vitro and in vivo, as measured by emergence of rifampin resistance. SNAP blocked the ability of the RecA protein to bind to single-stranded DNA in an electrophoretic mobility shift assay (EMSA) in vitro, an early event in the SOS response. The inhibitory effects of SNAP were additive with those of zinc acetate.

Conclusions

Nitric oxide donors blocked the initiation step of the SOS response. Downstream effects of this blockade included inhibition of Stx production and of hypermutation. Infection of rabbit loops with STEC resulted in a downregulation, rather than stimulation, of nitric oxide host defenses at 20 h of infection.

Tyrosine tRNA synthetase as a novel extracellular immunomodulatory protein in Streptococcus anginosus

Streptococcus anginosus is frequently detected in patients with infective endocarditis, abscesses or oral cancer. Although S. anginosus is considered the causative pathogen of these diseases, the pathogenic mechanisms of the bacterium have remained unclear. Previously, we suggested that an extracellular antigen from S. anginosus (SAA) serves as a pathogenic factor by inducing nitric oxide production in murine macrophages. In the present study, we identified SAA using LC-MS/MS and assessed the biological activities of His-tagged recombinant SAA in murine macrophages. SAA was identified as a tyrosine tRNA synthetase (SaTyrRS) that was isolated from the extracellular fraction of S. anginosus but not from other oral streptococci. In addition, inducible nitric oxide synthase and TNF-α mRNA expression was induced in recombinant SaTyrRS-stimulated murine macrophages. However, their mRNA expression was not induced in macrophages stimulated with truncated or heat-inactivated recombinant SaTyrRS, and the activation motif was identified as Arg264-Thr270. Consequently, these results indicated that SaTyrRS could be a novel and specific immunomodulatory protein in S. anginosus.

β-Cyclodextrin Inhibits Monocytic Adhesion to Endothelial Cells through Nitric Oxide-Mediated Depletion of Cell Adhesion Molecules

Cyclodextrins (CDs) are used as drug delivery agents. In this study, we examined whether CDs have an inflammatory effect on endothelial cells. First, we found that β-CD promoted cell proliferation in bovine aortic endothelial cells and elevated nitric oxide (NO) production through dephosphorylation of threonine-495 (T-495) in endothelial nitric oxide synthetase (eNOS). Dephosphorylation of T-495 is known to activate eNOS. Phosphorylation of T-495 was found to be catalyzed by protein kinase Cε (PKCε). We then found that β-CD inhibits binding of PKCε to diacylglycerol (DAG) via formation of a β-CD-DAG complex, indicating that β-CD inactivates PKCε. Furthermore, β-CD controls activation of PKCε by reducing the recruitment of PKCε into the plasma membrane. Finally, β-CD inhibits expression of intercellular and vascular cell adhesion molecule-1 by increasing NO via control of PKCε/eNOS and suppression of THP-1 cell adhesion to endothelial cells. These findings imply that β-CD plays an important role in anti-inflammatory processes.

Radix Ilicis Pubescentis total flavonoids ameliorates neuronal damage and reduces lesion extent in a mouse model of transient ischemic attack

Flavonoids are a major component in the traditional Chinese medicine Radix Ilicis Pubescentis. Previous studies have shown that the administration of Radix Ilicis Pubescentis total flavonoids is protective in cerebral ischemia. However, to our knowledge, no studies have examined whether the total flavonoids extracted from Radix Ilicis Pubescentis prevent or ameliorate neuronal damage following transient ischemic attacks. Therefore, Radix Ilicis Pubescentis total flavonoids question and the potential underlying mechanisms. Thus, beginning 3 days before the induction of a mouse model of transient ischemic attack using tert-butyl hydroperoxide injections, mice were intragastrically administered 0.3, 0.15, or 0.075 g/kg of Radix Ilicis Pubescentis total flavonoids daily for 10 days. The results of spectrophotometric analyses demonstrated that Radix Ilicis Pubescentis total flavonoids enhanced oxygen free radical scavenging and reduced pathological alterations in the brain. Hematoxylin-eosin staining results showed that Radix Ilicis Pubescentis total flavonoids reduced hippocampal neuronal damage and cerebral vascular injury in this mouse model of transient ischemic attack. These results suggest that the antioxidant effects of Radix Ilicis Pubescentis total flavonoids alleviate the damage to brain tissue caused by transient ischemic attack.

Endothelial nitric oxide synthetase genetic variants, metabolic syndrome and endothelial function in schizophrenia

OBJECTIVE

The increasing rates of metabolic syndrome and cardiovascular disease in schizophrenia led to investigation into their causes, including atypical antipsychotics and pharmacogenetic variants. This study focused on the peripheral vasculature as a cardiovascular phenotype and the influence of atypical antipsychotics, the aberrant metabolism of nitric oxide caused by endothelial nitric oxide synthetase (eNOS) genetic variants and metabolic syndrome in a cross-sectional sample of schizophrenia subjects.

METHODS

Associations between eNOS genetic variants and endothelial function was assessed in a cohort of schizophrenia patients taking antipsychotic drugs, whom were undergoing a clinical assessment for endothelial function via the method of peripheral artery tonometry (RH-PAT), as well as metabolic syndrome criteria screening. Analyses were conducted on the entire cohort, then again after stratifying by metabolic syndrome, to investigate the effect of the eNOS variants and metabolic syndrome on endothelial functionality.

RESULTS

We included 203 subjects with a mean age of 46 years. The cohort was 36% female, 36% had metabolic syndrome and 85% were currently using atypical antipsychotics. We found associations between the eNOS T⁻⁷⁸⁶C and worse endothelial functioning (lower RH-PAT values) only in schizophrenia patients without metabolic syndrome.

CONCLUSIONS

Our results suggested that when schizophrenia patients progress to meet metabolic syndrome criteria, the genetic protection of the eNOS T⁻⁷⁸⁶C variant on endothelial function is no longer seen: Other factors of this pro-inflammatory state may be overriding this effect. The results of this study need replication and the factors driving endothelial dysfunction in patients with metabolic syndrome warrant further investigation.

Endothelial nitric oxide synthetase genetic variants, metabolic syndrome and endothelial function in schizophrenia

OBJECTIVE

The increasing rates of metabolic syndrome and cardiovascular disease in schizophrenia led to investigation into their causes, including atypical antipsychotics and pharmacogenetic variants. This study focused on the peripheral vasculature as a cardiovascular phenotype and the influence of atypical antipsychotics, the aberrant metabolism of nitric oxide caused by endothelial nitric oxide synthetase (eNOS) genetic variants and metabolic syndrome in a cross-sectional sample of schizophrenia subjects.

METHODS

Associations between eNOS genetic variants and endothelial function was assessed in a cohort of schizophrenia patients taking antipsychotic drugs, whom were undergoing a clinical assessment for endothelial function via the method of peripheral artery tonometry (RH-PAT), as well as metabolic syndrome criteria screening. Analyses were conducted on the entire cohort, then again after stratifying by metabolic syndrome, to investigate the effect of the eNOS variants and metabolic syndrome on endothelial functionality.

RESULTS

We included 203 subjects with a mean age of 46 years. The cohort was 36% female, 36% had metabolic syndrome and 85% were currently using atypical antipsychotics. We found associations between the eNOS T⁻⁷⁸⁶C and worse endothelial functioning (lower RH-PAT values) only in schizophrenia patients without metabolic syndrome.

CONCLUSIONS

Our results suggested that when schizophrenia patients progress to meet metabolic syndrome criteria, the genetic protection of the eNOS T⁻⁷⁸⁶C variant on endothelial function is no longer seen: Other factors of this pro-inflammatory state may be overriding this effect. The results of this study need replication and the factors driving endothelial dysfunction in patients with metabolic syndrome warrant further investigation.

Clinical perspective on oxidative stress in sporadic amyotrophic lateral sclerosis

Sporadic amyotrophic lateral sclerosis (ALS) is one of the most devastating neurological diseases; most patients die within 3 to 4 years after symptom onset. Oxidative stress is a disturbance in the pro-oxidative/antioxidative balance favoring the pro-oxidative state. Autopsy and laboratory studies in ALS indicate that oxidative stress plays a major role in motor neuron degeneration and astrocyte dysfunction. Oxidative stress biomarkers in cerebrospinal fluid, plasma, and urine are elevated, suggesting that abnormal oxidative stress is generated outside of the central nervous system. Our review indicates that agricultural chemicals, heavy metals, military service, professional sports, excessive physical exertion, chronic head trauma, and certain foods might be modestly associated with ALS risk, with a stronger association between risk and smoking. At the cellular level, these factors are all involved in generating oxidative stress. Experimental studies indicate that a combination of insults that induce modest oxidative stress can exert additive deleterious effects on motor neurons, suggesting that multiple exposures in real-world environments are important. As the disease progresses, nutritional deficiency, cachexia, psychological stress, and impending respiratory failure may further increase oxidative stress. Moreover, accumulating evidence suggests that ALS is possibly a systemic disease. Laboratory, pathologic, and epidemiologic evidence clearly supports the hypothesis that oxidative stress is central in the pathogenic process, particularly in genetically susceptive individuals. If we are to improve ALS treatment, well-designed biochemical and genetic epidemiological studies, combined with a multidisciplinary research approach, are needed and will provide knowledge crucial to our understanding of ALS etiology, pathophysiology, and prognosis.

Nanotechnology as a therapeutic tool to combat microbial resistance

Use of nanoparticles is among the most promising strategies to overcome microbial drug resistance. This review article consists of three parts. The first part discusses the epidemiology of microbial drug resistance. The second part describes mechanisms of drug resistance used by microbes. The third part explains how nanoparticles can overcome this resistance, including the following: Nitric oxide-releasing nanoparticles (NO NPs), chitosan-containing nanoparticles (chitosan NPs), and metal-containing nanoparticles all use multiple mechanisms simultaneously to combat microbes, thereby making development of resistance to these nanoparticles unlikely. Packaging multiple antimicrobial agents within the same nanoparticle also makes development of resistance unlikely. Nanoparticles can overcome existing drug resistance mechanisms, including decreased uptake and increased efflux of drug from the microbial cell, biofilm formation, and intracellular bacteria. Finally, nanoparticles can target antimicrobial agents to the site of infection, so that higher doses of drug are given at the infected site, thereby overcoming resistance.

A molecular mechanism of optic nerve regeneration in fish: the retinoid signaling pathway

The fish optic nerve regeneration process takes more than 100 days after axotomy and comprises four stages: neurite sprouting (1-4 days), axonal elongation (5-30 days), synaptic refinement (35-80 days) and functional recovery (100-120 days). We screened genes specifically upregulated in each stage from axotomized fish retina. The mRNAs for heat shock protein 70 and insulin-like growth factor-1 rapidly increased in the retinal ganglion cells soon after axotomy and function as cell-survival factors. Purpurin mRNA rapidly and transiently increased in the photoreceptors and purpurin protein diffusely increased in all nuclear layers at 1-4 days after injury. The purpurin gene has an active retinol-binding site and a signal peptide. Purpurin with retinol functions as a sprouting factor for thin neurites. This neurite-sprouting effect was closely mimicked by retinoic acid and blocked by its inhibitor. We propose that purpurin works as a retinol transporter to supply retinoic acid to damaged RGCs which in turn activates target genes. We also searched for genes involved in the second stage of regeneration. The mRNA of retinoid-signaling molecules increased in retinal ganglion cells at 7-14 days after injury and tissue transglutaminase and neuronal nitric oxide synthase mRNAs, RA-target genes, increased in retinal ganglion cells at 10-30 days after injury. They function as factors for the outgrowth of thick, long neurites. Here we present a retinoid-signaling hypothesis to explain molecular events during the early stages of optic nerve regeneration in fish.

Nanotechnology as a therapeutic tool to combat microbial resistance

Use of nanoparticles is among the most promising strategies to overcome microbial drug resistance. This review article consists of three parts. The first part discusses the epidemiology of microbial drug resistance. The second part describes mechanisms of drug resistance used by microbes. The third part explains how nanoparticles can overcome this resistance, including the following: Nitric oxide-releasing nanoparticles (NO NPs), chitosan-containing nanoparticles (chitosan NPs), and metal-containing nanoparticles all use multiple mechanisms simultaneously to combat microbes, thereby making development of resistance to these nanoparticles unlikely. Packaging multiple antimicrobial agents within the same nanoparticle also makes development of resistance unlikely. Nanoparticles can overcome existing drug resistance mechanisms, including decreased uptake and increased efflux of drug from the microbial cell, biofilm formation, and intracellular bacteria. Finally, nanoparticles can target antimicrobial agents to the site of infection, so that higher doses of drug are given at the infected site, thereby overcoming resistance.

Effects of inflammation and axotomy on expression of acetylcholine transferase and nitric oxide synthetase within the cocaine- and amphetamine-regulated transcript-immunoreactive neurons of the porcine descending colon

This study reports changes in expression of acetylcholine transferase (AChT) and nitric oxide synthetase (NOS) in neurons immunoreactive for cocaine- and amphetamine-regulated transcript (CART) peptides during chemically-driven inflammation and axotomy in the porcine descending colon. The co-localization of the neurotransmitters with CART was studied by double immunofluorescence in the myenteric plexus (MP) and outer submucosal plexus (OSP) of the porcine descending colon under physiological and selected pathological conditions. In control animals, neurons expressing CART also expressed AChT in 25.37 ± 0.98% and 26.73 ± 0.96% in the MP and OSP, respectively. Neuronal co-expression of CART with NOS occurred in 90.66 ± 2.13% and 88.09 ± 2.96% in the MP and OSP, respectively. Following axotomy the number of neurons co-expressing CART and AChT decreased to 16.50 ± 3.20% in the MP and increased to 35.49 ± 2.04% in the OSP, while the number of neurons co-expressing CART and NOS increased to 96.66 ± 2.38% in the MP and 97.46 ± 2.22% in the OSP. Experimentally-induced colitis resulted in an increase in the number of neurons co-expressing CART and AChT to 42.40 ± 2.28% in the MP and 63.62 ± 1.83% in the OSP. Similarly, in these animals the number of neurons co-expressing CART and NOS increased to 93.9 ± 2.58% in the MP and 90.43 ± 2.09% in the OSP. Sham-operated controls showed expression levels of 26.22 ± 0.66% (MP) and 27.02 ± 1.73% (OSP) for simultaneous CART and AChT expression and 94.18 ± 0.93% (MP) and 88.21 ± 0.81% (OSP) for CART and NOS co-localization. These data confirm that the examined neurotransmitters have a role in traumatic and inflammatory responses of enteric neurons.