Stimulation of synaptoneurosome glutamate release by monomeric and fibrillated α‐synuclein

The α‐synuclein protein exists in vivo in a variety of covalently modified and aggregated forms associated with Parkinson's disease (PD) pathology. However, the specific proteoform structures involved with neuropathological disease mechanisms are not clearly defined. Since α‐synuclein plays a role in presynaptic neurotransmitter release, an in vitro enzyme‐based assay was developed to measure glutamate release from mouse forebrain synaptoneurosomes (SNs) enriched in synaptic endings. Glutamate measurements utilizing SNs from various mouse genotypes (WT, over‐expressers, knock‐outs) suggested a concentration dependence of α‐synuclein on calcium/depolarization‐dependent presynaptic glutamate release from forebrain terminals. In vitro reconstitution experiments with recombinant human α‐synuclein proteoforms including monomers and aggregated forms (fibrils, oligomers) produced further evidence of this functional impact. Notably, brief exogenous applications of fibrillated forms of α‐synuclein enhanced SN glutamate release but monomeric forms did not, suggesting preferential membrane penetration and toxicity by the aggregated forms. However, when applied to brain tissue sections just prior to homogenization, both monomeric and fibrillated forms stimulated glutamate release. Immuno‐gold and transmission electron microscopy (TEM) detected exogenous fibrillated α‐synuclein associated with numerous SN membranous structures including synaptic terminals. Western blots and immuno‐gold TEM were consistent with SN internalization of α‐synuclein. Additional studies revealed no evidence of gross disruption of SN membrane integrity or glutamate transporter function by exogenous α‐synuclein. Overall excitotoxicity, due to enhanced glutamate release in the face of either overexpressed monomeric α‐synuclein or extrasynaptic exposure to fibrillated α‐synuclein, should be considered as a potential neuropathological pathway during the progression of PD and other synucleinopathies. © 2017 Wiley Periodicals, Inc.     

Novel electrochemical xanthine biosensor based on chitosan–polypyrrole–gold nanoparticles hybrid bio-nanocomposite platform

The aim of this study was the electrochemical detection of the adenosine-3-phosphate degradation product, xanthine, using a new xanthine biosensor based on a hybrid bio-nanocomposite platform which has been successfully employed in the evaluation of meat freshness. In the design of the amperometric xanthine biosensor, chitosan–polypyrrole–gold nanoparticles fabricated by an in situ chemical synthesis method on a glassy carbon electrode surface was used to enhance electron transfer and to provide good enzyme affinity. Electrochemical studies were carried out by the modified electrode with immobilized xanthine oxidase on it, after which the biosensor was tested to ascertain the optimization parameters. The Biosensor exhibited a very good linear range of 1–200 μM, low detection limit of 0.25 μM, average response time of 8 seconds, and was not prone to significant interference from uric acid, ascorbic acid, glucose, and sodium benzoate. The resulting bio-nanocomposite xanthine biosensor was tested with fish, beef, and chicken real-sample measurements.     

Melatonin nephroprotective action in Zucker diabetic fatty rats involves its inhibitory effect on NADPH oxidase

Excessive activity of NADPH oxidase (Nox) is considered to be of importance for the progress of diabetic nephropathy. The aim of the study was to elucidate the effect of melatonin, known for its nephroprotective properties, on Nox activity under diabetic conditions. The experiments were performed on three groups of animals: (i) untreated lean (?/+) Zucker diabetic fatty (ZDF) rats; (ii) untreated obese diabetic (fa/fa) ZDF rats; and (iii) ZDF fa/fa rats treated with melatonin (20 mg/L) in drinking water. Urinary albumin excretion was measured weekly. After 4 wk of the treatment, the following parameters were determined in kidney cortex: Nox activity, expression of subunits of the enzyme, their phosphorylation and subcellular distribution. Histological studies were also performed. Compared to ?/+ controls, ZDF fa/fa rats exhibited increased renal Nox activity, augmented expression of Nox4 and p47^phox subunits, elevated level of p47^phox phosphorylation, and enlarged phospho‐p47^phox and p67^phox content in membrane. Melatonin administration to ZDF fa/fa rats resulted in the improvement of renal functions, as manifested by considerable attenuation of albuminuria and some amelioration of structural abnormalities. The treatment turned out to nearly normalize Nox activity, which was accompanied by considerably lowered expression and diminished membrane distribution of regulatory subunits, that is, phospho‐p47^phox and p67^phox. Thus, it is concluded that: (i) melatonin beneficial action against diabetic nephropathy involves attenuation of the excessive activity of Nox; and (ii) the mechanism of melatonin inhibitory effect on Nox is based on the mitigation of expression and membrane translocation of its regulatory subunits.     

Association of low-activity MAOA allelic variants with violent crime in incarcerated offenders

The main enzyme for serotonin degradation, monoamine oxidase (MAO) A, has recently emerged as a key biological factor in the predisposition to impulsive aggression. Male carriers of low-activity variants of the main functional polymorphism of the MAOA gene (MAOA-uVNTR) have been shown to exhibit a greater proclivity to engage in violent acts. Thus, we hypothesized that low-activity MAOA-uVNTR alleles may be associated with a higher risk for criminal violence among male offenders. To test this possibility, we analyzed the MAOA-uVNTR variants of violent (n = 49) and non-violent (n = 40) male Caucasian and African-American convicts in a correctional facility. All participants were also tested with the Childhood Trauma Questionnaire (CTQ), Barratt Impulsivity Scale (BIS-11) and Buss-Perry Aggression Questionnaire (BPAQ) to assess their levels of childhood trauma exposure, impulsivity and aggression, respectively. Our results revealed a robust (P < 0.0001) association between low-activity MAOA-uVNTR alleles and violent crime. This association was replicated in the group of Caucasian violent offenders (P < 0.01), but reached only a marginal trend (P = 0.08) in their African American counterparts. While violent crime charges were not associated with CTQ, BIS-11 and BPAQ scores, carriers of low-activity alleles exhibited a mild, yet significant (P < 0.05) increase in BIS-11 total and attentional-impulsiveness scores. In summary, these findings support the role of MAOA gene as a prominent genetic determinant for criminal violence. Further studies are required to confirm these results in larger samples of inmates and evaluate potential interactions between MAOA alleles and environmental vulnerability factors.     

[11C]befloxatone distribution is well correlated to monoamine oxidase A protein levels in the human brain

[¹¹C]befloxatone is a positron emission tomography radioligand to image monoamine oxidase A (MAO-A) in the brain, which has been used in preclinical studies and in clinical protocols. However, a recent study found that [¹¹C]befloxatone binding potential (k₃/k₄) has a poor correlation with MAO-A protein levels measured in the human brain. We here show that this poor correlation only depends on the choice of the parameter when performing kinetic modeling. In particular, the total volume of distribution of [¹¹C]befloxatone shows a tight correlation with both protein and mRNA levels of MAO-A in the human brain.     

Monoamine Oxidase Inhibitor Poisoning Resulting from Internet Misinformation on Illicit Substances

The Internet may represent a new mechanism by which adolescents initiate the use of illicit substances. The existence of multiple partisan websites providing misinformation regarding the safety of these substances may lead to an increase in unsafe behavior among this age group. Adverse outcomes related to Internet‐based drug information are rarely identified. We report a case of an adolescent whose use of the Internet to obtain drug information led to severe poisoning from the combination of a monoamine oxidase inhibitor, harmaline, and a hallucinogenic tryptamine, 5‐methoxydimethyltryptamine (5‐MeO‐DMT).     

Hypouricemic effect of the methanol extract from Prunus mume fruit in mice

Context: The fruit of the Prunus mume Sieb. et Zucc (Rosaceae) is used as a health food or medicinal material in traditional herb medicine for a long time in Eastern Asian countries.

Objective: Our present study investigated the hypouricemic effect of the methanol extract from P. mume fruit (MPMF) in mice with potassium oxonate-induced hyperuremia.

Materials and methods: Effect of MPMF (35, 70 and 140 mg/kg, p.o.) administrated for 7 days on the serum, liver, urinary uric acid levels and liver xanthine oxidase (XO) activity were assessed in mice.

Results: Hyperuricemic mice induced by potassium oxonate demonstrated an elevation in serum and liver uric acid levels (11.0 mg/dL and 0.52 mg/g tissue) and a reduction in urinary uric acid levels (49.9 mg/dL). Oral administration of 140 mg/kg MPMF for 7 days reversed the abnormalities in serum, liver and urinary uric acid levels (7.1 mg/dL, 0.37 mg/g tissue and 69.7 mg/dL, respectively). In addition, 70 and 140 mg/kg MPMF (3.1 and 2.9 nmol/min per mg protein) inhibited liver XO activity compared with hyperuricemic mice (3.9 nmol/min per mg protein).

Discussion and conclusion: The results indicated that the beneficial hypouricaemic effect of MPMF may be mediated, at least in part, by inhibiting XO activity in the liver. Our study suggests that P. mume and its extracts may have a considerable potential for development as an anti-gout agent for clinical application.     

Mitochondrial redox responses to cerebral ischaemia produced by four-vessel occlusion in the rat

Changes in reduction/oxidation (redox) ratios of the initial and terminal members of the mitochondrial respiratory chain (nicotine adenine dinucleotide and cytochrome a, a₃) were measured by fluorometry and reflection spectrophotometry in rat cerebral cortex. Three patterns of responses were observed during the transition to global ischaemia produced by electrocoagulation of the vertebral arteries and carotid artery ligation. Most often, arterial occlusion was accompanied by shins towards reduction of the mitochondrial components followed by partial reoxidation and then further reduction. Less frequently, ischaemia produced reductive shifts of the respiratory chain reactants that rapidly reached maximal values. In some rats, however, arterial, occlusion produced mitochondrial reduction followed by partial or complete reoxidation. ECoG remained suppressed, despite mitochondrial reoxidation, in approximately 1/3 of the latter animals. This study demonstrates that responses to 4-vessel occlusion can vary greatly among animals and suggests that monitoring of signals of ischaemic insult, such as mitochondrial redox status, may offer advantages for assessment of the consequences of ischaemic insult.     

Microenvironment and tumor cell plasticity: An easy way out

Cancer cells undergo genetic changes allowing their adaptation to environmental changes, thereby obtaining an advantage during the long metastatic route, disseminated of several changes in the surrounding environment. In particular, plasticity in cell motility, mainly due to epigenetic regulation of cancer cells by environmental insults, engage adaptive strategies aimed essentially to survive in hostile milieu, thereby escaping adverse sites. This review is focused on tumor microenvironment as a collection of structural and cellular elements promoting plasticity and adaptive programs. We analyze the role of extracellular matrix stiffness, hypoxia, nutrient deprivation, acidity, as well as different cell populations of tumor microenvironment.