Sex differences in antioxidant defence and the regulation of redox homeostasis in physiology and pathology

Reactive oxygen species (ROS) is a term that defines a group of unstable compounds derived from exogenous sources or endogenous metabolism. Under physiological conditions, low levels of ROS play a key role in the regulation of signal transduction- or transcription-mediated cellular responses. In contrast, excessive and uncontrolled loading of ROS results in a pathological state known as oxidative stress (OS), a leading contributor to aging and a pivotal factor for the onset and progression of many disorders. Evolution has endowed cells with an antioxidant system involved in stabilizing ROS levels to a specific threshold, preserving ROS-induced signalling function and limiting negative side effects. In mammals, a great deal of evidence indicates that females defence against ROS is more proficient than males, determining a longer lifespan and lower incidence of most chronic diseases. In this review, we will summarize the most recent sex-related differences in the regulation of redox homeostasis. We will highlight the peculiar aspects of the antioxidant defence in sex-biased diseases whose onset or progression is driven by OS, and we will discuss the molecular, genetic, and evolutionary determinants of female proficiency to cope with ROS.

A novel colistin adjuvant identified by virtual screening for ArnT inhibitors

Background

Colistin is a last-resort treatment option for many MDR Gram-negative bacteria. The covalent addition of l-aminoarabinose to the lipid A moiety of LPS is the main colistin resistance mechanism in the human pathogen Pseudomonas aeruginosa.

Objectives

Identification (by in silico screening of a chemical library) of potential inhibitors of ArnT, which catalyses the last committed step of lipid A aminoarabinosylation, and their validation in vitro as colistin adjuvants.

Methods

The available ArnT crystal structure was used for a docking-based virtual screening of an in-house library of natural products. The resulting putative ArnT inhibitors were tested in growth inhibition assays using a reference colistin-resistant P. aeruginosa strain. The most promising compound was further characterized for its range of activity, specificity and cytotoxicity. Additionally, the effect of the compound on lipid A aminoarabinosylation was verified by MS analyses of lipid A.

Results

A putative ArnT inhibitor (BBN149) was discovered by molecular docking and demonstrated to specifically potentiate colistin activity in colistin-resistant P. aeruginosa isolates, without relevant effect on colistin-susceptible strains. BBN149 also showed adjuvant activity against colistin-resistant Klebsiella pneumoniae and low toxicity to bronchial epithelial cells. Lipid A aminoarabinosylation was reduced in BBN149-treated cells, although only partially.

Conclusions

This study demonstrates that in silico screening targeting ArnT can successfully identify inhibitors of colistin resistance and provides a promising lead compound for the development of colistin adjuvants for the treatment of MDR bacterial infections.

ent-Beyerane Diterpenes as a Key Platform for the Development of ArnT-Mediated Colistin Resistance Inhibitors

Colistin is a last-resort antibiotic for the treatment of multidrug resistant Gram-negative bacterial infections. Recently, a natural ent-beyerene diterpene was identified as a promising inhibitor of the enzyme responsible for colistin resistance mediated by lipid A aminoarabinosylation in Gram-negative bacteria, namely, ArnT (undecaprenyl phosphate-alpha-4-amino-4-deoxy-l-arabinose arabinosyl transferase). Here, semisynthetic analogues of hit were designed, synthetized, and tested against colistin-resistant Pseudomonas aeruginosa strains including clinical isolates to exploit the versatility of the diterpene scaffold. Microbiological assays coupled with molecular modeling indicated that for a more efficient colistin adjuvant activity, likely resulting from inhibition of the ArnT activity by the selected compounds and therefore from their interaction with the catalytic site of ArnT, an ent-beyerane scaffold is required along with an oxalate-like group at C-18/C-19 or a sugar residue at C-19 to resemble L-Ara4N. The ent-beyerane skeleton is identified for the first time as a privileged scaffold for further cost-effective development of valuable colistin resistance inhibitors.

Effect of lipid A aminoarabinosylation on Pseudomonas aeruginosa colistin resistance and fitness

Colistin represents the last-line treatment option against many multidrug-resistant Gram-negative pathogens. Several lines of evidence indicate that aminoarabinosylation of the lipid A moiety of lipopolysaccharide (LPS) is an essential step for the development of colistin resistance in Pseudomonas aeruginosa. However, whether it is sufficient to confer resistance in this bacterium remains unclear. The aim of this work was to investigate the specific contribution of lipid A aminoarabinosylation to colistin resistance in P. aeruginosa and evaluate the effect of this resistance mechanism on bacterial fitness. Recombinant strains constitutively expressing the enzymes for lipid A aminoarabinosylation were generated in a small collection of reference and clinical isolates and verified by quantitative reverse transcription polymerase chain reaction (qRT-PCR), lipid A extraction and mass spectrometry. The effect of aminoarabinosylated lipid A on colistin resistance was found to be strain- and culture condition-dependent. Higher levels of resistance were generally obtained in the presence of divalent cations, which appear to be important for aminoarabinosylation-mediated colistin resistance. High colistin resistance was also observed for most strains in human serum and in artificial sputum medium, which should partly mimic growth conditions during infection. The results of growth, biofilm, cell envelope integrity and Galleria mellonella infection assays indicate that lipid A aminoarabinosylation does not cause relevant fitness costs in P. aeruginosa.

Janus effect of glucocorticoids on differentiation of muscle fibro/adipogenic progenitors

Muscle resident fibro-adipogenic progenitors (FAPs), support muscle regeneration by releasing cytokines that stimulate the differentiation of myogenic stem cells. However, in non-physiological contexts (myopathies, atrophy, aging) FAPs cause fibrotic and fat infiltrations that impair muscle function. We set out to perform a fluorescence microscopy-based screening to identify compounds that perturb the differentiation trajectories of these multipotent stem cells. From a primary screen of 1,120 FDA/EMA approved drugs, we identified 34 compounds as potential inhibitors of adipogenic differentiation of FAPs isolated from the murine model (mdx) of Duchenne muscular dystrophy (DMD). The hit list from this screen was surprisingly enriched with compounds from the glucocorticoid (GCs) chemical class, drugs that are known to promote adipogenesis in vitro and in vivo. To shed light on these data, three GCs identified in our screening efforts were characterized by different approaches. We found that like dexamethasone, budesonide inhibits adipogenesis induced by insulin in sub-confluent FAPs. However, both drugs have a pro-adipogenic impact when the adipogenic mix contains factors that increase the concentration of cAMP. Gene expression analysis demonstrated that treatment with glucocorticoids induces the transcription of Gilz/Tsc22d3, an inhibitor of the adipogenic master regulator PPARγ, only in anti-adipogenic conditions. Additionally, alongside their anti-adipogenic effect, GCs are shown to promote terminal differentiation of satellite cells. Both the anti-adipogenic and pro-myogenic effects are mediated by the glucocorticoid receptor and are not observed in the presence of receptor inhibitors. Steroid administration currently represents the standard treatment for DMD patients, the rationale being based on their anti-inflammatory effects. The findings presented here offer new insights on additional glucocorticoid effects on muscle stem cells that may affect muscle homeostasis and physiology.

Genetic Basis and Physiological Effects of Lipid A Hydroxylation in Pseudomonas aeruginosa PAO1

Modifications of the lipid A moiety of lipopolysaccharide influence the physicochemical properties of the outer membrane of Gram-negative bacteria. Some bacteria produce lipid A with a single hydroxylated secondary acyl chain. This hydroxylation is catalyzed by the dioxygenase LpxO, and is important for resistance to cationic antimicrobial peptides (e.g., polymyxins), survival in human blood, and pathogenicity in animal models. The lipid A of the human pathogen Pseudomonas aeruginosa can be hydroxylated in both secondary acyl chains, but the genetic basis and physiological role of these hydroxylations are still unknown. Through the generation of single and double deletion mutants in the lpxO1 and lpxO2 homologs of P. aeruginosa PAO1 and lipid A analysis by mass spectrometry, we demonstrate that both LpxO1 and LpxO2 are responsible for lipid A hydroxylation, likely acting on different secondary acyl chains. Lipid A hydroxylation does not appear to affect in vitro growth, cell wall stability, and resistance to human blood or antibiotics in P. aeruginosa. In contrast, it is required for infectivity in the Galleria mellonella infection model, without relevantly affecting in vivo persistence. Overall, these findings suggest a role for lipid A hydroxylation in P. aeruginosa virulence that could not be directly related to outer membrane integrity.

Different Omega-3 Formulations Yield to Diverse Clinical Response: A Case-Report

Treatment guidelines recommend omega-3 with Docosahexaenoic Acid (DHA) and Eicosapentaenoic Acid (EPA) content not above 85% in patients with high plasma levels of triglycerides. Since the different up to date formulation of omega-3 available in commerce must be similar to clinical efficacy and safety, herein, we report the case a 52-year-old woman who presented clinical inefficacy using Olevia(®) omega-3 treatment. Clinical evaluation excluded the presence of intestinal or systemic diseases able to reduce the drug absorption. Switching the therapy from (Olevia(®)) to an equivalent omega-3 formulation (Esapent(®)), we documented a decrease in her plasma triglycerides levels. In order to evaluate a possible difference between these formulations we performed a single blind in vitro dissolution test using three pills for each formulation of omega-3 (Olevia(®), Esapent® and another one chosen between the several formulations available in commerce: DOC Generic(®)) that revealed a significant difference (>20%) in the dissolution time of three different omega- 3 commercially available drug formulation.

Matrix metalloproteinases and risk stratification in patients undergoing surgical revascularisation for critical limb ischaemia

Critical limb ischaemia (CLI) is the most advanced form of peripheral artery disease (PAD) and it is often associated with foot gangrene, which may lead to major amputation of lower limbs, and also with a higher risk of death due to fatal cardiovascular events. Matrix metalloproteinases (MMPs) seem to be involved in atherosclerosis, PAD and CLI. Aim of this study was to evaluate variations in MMP serum levels in patients affected by CLI, before and after lower limb surgical revascularisation through prosthetic or venous bypass. A total of 29 patients (7 females and 22 males, mean age 73·4 years, range 65-83 years) suffering from CLI and submitted to lower extremity bypass (LEB) in our Institution were recruited. Seven patients (group I) underwent LEB using synthetic polytetrafluoroethylene (PTFE) graft material and 22 patients (group II) underwent LEB using autogenous veins. Moreover, 30 healthy age-sex-matched subjects were also enrolled as controls (group III). We documented significantly higher serum MMPs levels (P < 0·01) in patients with CLI (groups I and II) with respect to control group (group III). Finally, five patients with CLI (17·2%) showed poor outcomes (major amputations or death), and enzyme-linked immunosorbent assay (ELISA) test showed very high levels of MMP-1 and MMP-8. MMP serum levels seem to be able to predict the clinical outcomes of patients with CLI.

Frequency selective solutions for an efficient non-ionising radiation protection in the radiofrequency and microwave ranges

The paper introduces an efficient solution for the realisation of frequency-selective devices which can shield non-ionising radiation in the radiofrequency and microwave bandwidths. The identified hardware is transparent to visible light and it can be adapted to the shielding needs, both in terms of frequency and spatial behaviours. Being transparent, it can be effectively applied on windows that normally offer the worst attenuation coefficient to outdoor versus indoor penetration. The solution exhibits enhanced performance, it can be analysed with fast but exact numerical techniques and it can be manufactured by low-cost industrial procedures. To demonstrate the validity of the approach, an example has been designed, analysed and applied to the frequency spectrum occupied by upcoming wideband access base stations.

Neurofunctional effects in rats prenatally exposed to fluoxetine

In the treatment of depression fluoxetine [a selective serotonine reuptake inhibitor (SSRIs)] is a widely used drug in humans. The selectivity, efficacy, side effects and simplicity of dosage contributed to fluoxetine's clinical acceptance. Several psychiatric disorders (many of them responsive to SSRIs) are present during pregnancy; up to 10% of pregnant women fulfill diagnostic criteria for major or minor depression with an even higher percentage developing postpartum depression. Therefore, significant numbers of women may be taking SSRIs while pregnant. Since fluoxetine's safe use during pregnancy is not yet established and experimental studies inconclusive, we performed the present research in order to investigate the neurobehavioral effects produced in rats by prenatal exposure to fluoxetine (5 and 10 mg/kg/sc from day 13 to 20 of gestation) on cognitive functions, emotional reactivity and sexual performance.

Virtual musculo-skeletal model for the biomechanical analysis of the upper limb

In this paper, a musculo-skeletal model of the upper limb is presented. The limb is modelled as a three-dimensional 7 degrees-of-freedom system, linked to the shoulder, which has been considered as frame. The upper limb model is made up of four links corresponding to the most important body segments: the humerus, the ulna, the radius and the hand, considered as a single rigid body. Particular attention has been paid to the modelling of joints in order to mimic all the possible arm and forearm movements (including prono-supination). The model also includes 24 muscles. The mathematical model used to describe the muscles is that proposed by Zajac in 1989, modified by the authors. The kinematic analysis has been performed including an ergonomics index to take into account the posture and joint physical limits. Moreover an optimization criterion based on minimum activation pattern has been included in order to find muscular activation coefficients. The results of the proposed methodology concerning muscular activations have been compared to those coming from processed EMG signals, which have been acquired during experimental tests.

[Varix of the extra-hepatic portion of the fetal intra-abdominal umbilical vein: pathogenesis, prenatal sonographic diagnosis, and perinatal outcome]

AIM

Aim of the study was to investigate pathogenesis, diagnosis, and prognosis of the fetal intra-abdominal umbilical vein varix (FIUVV).

METHODS

We reviewed all cases of FIUVV diagnosed in our hospital from August 1999 to December 2002. The umbilical vein was considered dilated when the measurement was above 2 standard deviation of the mean for gestational age. In all cases prenatal echocardiography and post-natal karyotype were performed. Our cases were also considered in the light of all the cases of FIUVV reported in literature.

RESULTS

FIUVV was diagnosed in 5 cases between 22 and 37 weeks' gestation, among an unselected population of pregnant woman. Karyotype was normal in all cases; an apparently isolated septal ventricular defect was present in one patient. No obstetrical complications due to the presence of FIUVV (i.e. thrombosis) were associated.

CONCLUSIONS

In our case series no obstetrical complications, and only one mild fetal anomaly were present. In literature an high association has been reported between the presence of FIUVV and fetal anomalies and/or obstetrical complications. Fetal echocardiography and detailed US study of fetal anatomy is needed to exclude associated anomalies. Karyotype should be offered only when other fetal anomalies are present. In presence of FIUVV, a close fetal monitoring by serial color Doppler and ultrasonographic examinations should be performed.

[Effects on function of human lymphocytes exposed to electromagnetic fields with a frequency from 1,500 to 2,000 MHz]

Normal human peripheral blood lymphocytes were irradiated for 10 or 5 min with frequencies from 1.5 to 2.0 GHz. The frequency of 1.8 GHz overlaps that of mobile phones and leads to a significant reduction of the T-cell mediated antibacterial activity.

Kinetic properties of mitochondrial H+-adenosine triphosphatase in Morris hepatoma 3924A

A study of kinetic properties of mitochondrial ATPase in Morris hepatoma 3924A is reported. The results show that submitochondrial particles isolated from the tumor tissue exhibited a three-fold increase in both the Km for ATP hydrolysis and Ki for the competitive inhibitor [beta, gamma-imido]ATP with regard to normal rat liver. Eadie-Hofstee analysis of the kinetics of ATP hydrolysis show that both the high and the low affinity constants for ATP were enhanced in the hepatoma with respect to the rat liver enzyme. Kinetic analysis of passive proton conduction through the F0 sector of ATPase does not reveal any difference between Morris hepatoma and rat liver. In Morris hepatoma particles, 50% inhibition of the hydrolase activity required 10 times more oligomycin than in control particles. On the contrary, 50% inhibition of proton conduction occurred in both hepatoma and rat liver particles at the same concentration of oligomycin. It is concluded that in Morris hepatoma the catalytic process in F1 and the functional connection between F1 and F0 of the ATP synthase are altered with regard to control rat liver.

[Visco-elastic properties of various composites for the front teeth]

The rupture load, elasticity modulus and viscosity coefficient of certain composite currently on sale for the reconstruction of front teeth were calculated experimentally. The products examined were: Prismafil (Caulk), Helioprogress (Vivadent), Heliosit (Vivadent), Silux (3M), Concise (3M), Command Ultrafine (Kerr), P30 (3M). The figures obtained relate to 3 different time periods after the preparation of samples.

[Ionizing radiation and video computer terminals]

VDTs are more frequently being used and, therefore have given rise to the problem of security among operators exposed to possible X-ray emissions. The authors report the results of a dosimetric investigation, carried out through TLD CaF2:Dy on X-ray exposure levels close to video display terminals of a data processing center. After testing the exposure percentage values and the measurements adjusted to one-year basis, the authors report that the value are generally similar to those existing in the environment even though significant values have been found in a few cases.

The mechanism of transmembrane delta muH+ generation in mitochondria by cytochrome c oxidase

In rat liver mitochondria treated with rotenone, N-ethylmaleimide or oligomycin the expected alkalinization caused by proton consumption for aerobic oxidation of ferrocyanide was delayed with respect to ferrocyanide oxidation, unless carbonyl cyanide p-trifluoromethoxyphenylhydrazone was present. 2. When valinomycin or valinomycin plus antimycin were also present, ferricyanide, produced by oxidation of ferrocyanide, was re-reduced by hydrogenated endogenous reductants. Under these circumstances the expected net proton consumption caused by ferrocyanide oxidation was preceded by transient acidification. It is shown that re-reduction of formed ferricyanide and proton release derive from rotenone- and antimycin-resistant oxidation of endogenous reductants through the proton-translocating segments of the respiratory chain on the substrate side of cytochrome c. The number of protons released per electron flowing to ferricyanide varied, depending on the experimental conditions, from 3.6 to 1.5. 3. The antimycin-insensitive re-reduction of ferricyanide and proton release from mitochondria were strongly depressed by 2-n-heptyl-4-hydroxyquinoline N-oxide. This shows that the ferricyanide formed accepts electrons passing through the protonmotive segments of the respiratory chain at the level of cytochrome c and/or redox components of the cytochrome b-c1 complex situated on the oxygen side of the antimycin-inhibition site. Dibromothymoquinone depressed and duroquinol enhanced, in the presence of antimycin, the proton-release process induced by ferrocyanide respiration. Both quinones enhanced the rate of scalar proton production associated with ferrocyanide respiration, but lowered the number of protons released per electron flowing to the ferricyanide formed. 4. Net proton consumption caused by aerobic oxidation of exogenous ferrocytochrome c by antimycin-supplemented bovine heart mitochondria was preceded by scalar proton release, which was included in the stoicheiometry of 1 proton consumed per mol of ferrocytochrome c oxidized. This scalar proton production was associated with transition of cytochrome c from the reduced to the oxidized form and not to electron flow along cytochrome c oxidase. 5. It is concluded that cytochrome c oxidase only mediates vectorial electron flow from cytochrome c at the outer side to protons that enter the oxidase from the matrix side of the membrane. In addition to this consumption of protons the oxidase does not mediate vectorial proton translocation.