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Mitochondrial autophagy or mitophagy is a key process that allows selective sequestration and degradation of dysfunctional mitochondria to prevent excessive reactive oxygen species, and activation of cell death. Recent studies revealed that ubiquitin–proteasome complex activity and mitochondrial membrane rupture are key steps preceding mitophagy, in combination with the ubiquitination of specific outer mitochondrial membrane (OMM) proteins. The deubiquitinating enzyme ubiquitin‐specific peptidase 14 (USP14) has been shown to modulate both proteasome activity and autophagy. Here, we report that genetic and pharmacological inhibition of USP14 promotes mitophagy, which occurs in the absence of the well‐characterised mediators of mitophagy, PINK1 and Parkin. Critical to USP14‐induced mitophagy is the exposure of the LC3 receptor Prohibitin 2 by mitochondrial fragmentation and mitochondrial membrane rupture. Genetic or pharmacological inhibition of USP14 in vivo corrected mitochondrial dysfunction and locomotion behaviour of PINK1/Parkin mutant Drosophila model of Parkinson9s disease, an age‐related progressive neurodegenerative disorder that is correlated with diminished mitochondrial quality control. Our study identifies a novel therapeutic target that ameliorates mitochondrial dysfunction and in vivo PD‐related symptoms.

Recently many studies have focused on long-term follow-up of phenylketonuria (PKU McKusick 261600) patients, especially regarding discontinuation of diet in adulthood and subsequent possible neurological involvement. Neurological symptoms have been observed in some patients after discontinuation of diet, with improvements after reintroduction of a phenylalanine-restricted diet (Pietz et al 1998). Brain magnetic resonance imaging (MRI) revealed white-matter abnormalities in patients with neurological impairment but also in many patients without neurological symptoms (Burgard et al 1999). Myelin changes observed by brain MRI are similar in early-treated, late-treated and untreated patients, differing only in extension. Neurological investigations of treated adult PKU patients revealed minor neurological signs (tremor, brisk deep tendon reflexes, clumsy motor coordination) indicating the possibility of a specific neurological syndrome in adult PKU patients off diet. Even early-treated phenylketonuric patients show subtle symptoms of CNS damage, in addition to neuropsychological, neurophysiological and brain imaging abnormalities (Pietz et al 1998). Therefore, further investigations are necessary to evaluate the presence of biochemical changes, even in early-treated patients, that could be implicated in the neurological alterations. The aim of our study was to investigate dopamine and serotonin metabolism (homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA), respectively) in early-treated PKU patients with white-matter abnormalities on magnetic resonance imaging.

Oxidation reactions are essential biological reactions necessary for the formation of high-energy compounds used to fuel metabolic processes, but can be injurious to cells when produced in excess. Cutaneous tissue is especially susceptible to damage mediated by reactive oxygen species and low-density lipoprotein oxidation, triggered by dysmetabolic diseases, inflammation, environmental factors, or aging. Here we have examined the ability of the flavonoid quercetin to protect cutaneous tissue-associated cell types from injury induced by oxidative stress, and possible cooperative effects of ascorbic acid. Human skin fibroblasts, keratinocytes, and endothelial cells were cultured in the presence of buthionine sulfoximine (BSO), an irreversible inhibitor of glutathione (GSH) synthesis. Depletion of intracellular levels of GSH leads to an accumulation of cellular peroxides and eventual cell death. Quercetin concentration-dependently (EC50: 30-40 microM) reduced oxidative injury of BSO to all cell types, and was also effective when first added after BSO washout. BSO caused marked decreases in the intracellular level of GSH, which remained depressed in quercetin-protected cells. Ascorbic acid, while by itself not cytoprotective synergized with quercetin, lowered the quercetin EC50 and prolonged the window for cytoprotection. The related flavonoids rutin and dihydroquercetin also decreased BSO-induced injury to dermal fibroblasts, albeit less efficaciously so than quercetin. The cytoprotective effect of rutin, but not that of dihydroquercetin, was enhanced in the presence of ascorbic acid. Further, quercetin rescued sensory ganglion neurons from death provoked by GSH depletion. Direct oxidative injury to this last cell type has not been previously demonstrated. The results show that flavonoids are broadly protective for cutaneous tissue-type cell populations subjected to a chronic intracellular form of oxidative stress. Quercetin in particular, paired with ascorbic acid, may be of therapeutic benefit in protecting neurovasculature structures in skin from oxidative damage.

A sensitive and accurate assay was developed for the measurement of 8-methoxypsoralen in plasma using electron-impact positive-ion mass fragmentography. 4,5,8-Trimethylpsoralen was used as an internal standard. Sample preparation consisted of a two-step liquid phase extraction using acetonitrile and methylene chloride. The calibration curve showed a linear relationship between the peak areas of 8-methoxypsoralen and 4,5,8-trimethylpsoralen over a wide range of 8-methoxypsoralen concentrations (1–500 ng/ml). Within- and between-run precisions, measured at five different drug concentrations, varied from 0.82 to 1.41% and from 0.82 to 1.86%, respectively.

A series of experiments on rats have been performed, to study the effects of long time (50 days) exposure to electromagnetic fields of extremely low frequency (ELF, i.e. less than 100 Hz) and amplitude (non thermal), testing whether the metabolic processes would be affected. The background lies on recent observations on the behaviour of isolated enzymes in vitro exposed to EFL fields. In these experiments, the cyclotron (or Larmor) frequency of the metallic ion has been used to "stimulate" the metalloproteins redox-active site, thus obtaining a clear variation of the enzyme functionality. In this paper we have extended for the first time the check to more complex animal metabolism. The novelty of this approach implies that a large amount of data had to be analyzed since it was not possible, in principle, to select only a few parameters among all the potential effects. Several biochemical parameters have been evaluated by comparing their values during the periods of exposure (field ON) and non exposure (field OFF). The evidence that long term exposure to electromagnetic fields with a well defined frequency may have relevant effects on parameters such as body weight, blood glucose and fatty acid metabolism has been obtained.

Mast cells play a central role in both immediate allergic reactions and inflammation. A functional nerve-mast cell interaction has been proposed, given the morphological association between mast cells and neuropeptide-containing peripheral nerves. We now show that purified rat peritoneal mast cells contain large quantities of N-acetylaspartate (NAA; 747.50 nmol/mg of protein). Mast cell levels of NAA were rapidly reduced, by 64.0 and 86.4%, following treatment with compound 48/80 and mastoparan, respectively. These secretagogues strongly decreased mast cell histamine content over the same time period, suggesting also that NAA is stored in secretory granules. The data are the first to show that NAA is present in an immune effector cell type. Because NAA may be involved in myelin synthesis and glutamyl peptide metabolism, NAA released from mast cells following nervous or other stimuli could participate in neuroimmune interactions. Mast cells in multiple sclerosis plaques may contribute to the reported elevations in brain NAA in this disease.

SummaryIn a case-control study, fasting total homocysteinemia was determined in 208 consecutive outpatients who underwent phlebography because of the first episode of clinically suspected deep-vein thrombosis (DVT) of lower limbs. Contrast venography confirmed the clinical suspicion in 60 patients (28.8%). Hyperhomocysteinemia was detected in 15 of the 60 patients with DVT (25.0%), and in 17 of the 148 subjects without thrombosis (11.5%; p = 0.025). The OR for having an acute DVT in patients with hyperhomocysteinemia was 2.6 (95% Cl: 1.1-5.9). It is concluded that high plasma homocysteine levels are significantly associated with DVT in symptomatic patients. Further studies are needed to clarify the clinical implications of this association.

Canavan's disease is an autosomal recessive disorder characterized by a deficiency of aspartoacylase and accumulation of N-acetylaspartic acid (NAA), leading to a severe leukodystrophy and spongy degeneration of the brain. N-Acetylaspartylglutamate (NAAG), the presumed product of NAA, also accumulates in this disease. The endogenous dipeptide NAAG has been suggested to have low potency at NMDA receptors. Here we have tested the actions of NAAG and NAA on NMDA-evoked responses in cultured cerebellar granule cells. In differentiating granule cells grown in low-K+ medium, NAAG negated the survival-promoting effects of NMDA but not K+ depolarization. Neither NAAG nor NAA alone promoted cell survival in low-K+ medium. The modest trophic action of 50 microM kainic acid in low-K+ medium was reinforced by the NMDA receptor antagonist dizocilpine maleate and by NAAG. In K(+)-differentiated granule cells, NAAG raised the threshold of NMDA neurotoxicity but not that of kainate. The observed activities of NAAG were overcome by excess NMDA and were not mimicked by NAA. These data raise the possibility that disruption of NMDA receptor processes by NAAG may be of pathophysiological relevance.

N-Acetylglutamate synthetase (NAGS, EC 2.3.1.1), the deficiency of which (McKusick 23735) in humans has only previously been reported three times (Bachmann et al 1981, 1988; Elpeleg et al 1990), is a mitochondrial enzyme that normally catalyses the synthesis of N-acetylglutamate (NAG), an obligate activator of carbamoyl phosphate synthetase (CPS), which initiates the first step of urea synthesis from ammonia

The allopurinol challenge test was performed on 44 healthy subjects (28 children and 16 adolescents) in order to establish normal values of urinary orotic acid excretion following allopurinol ingestion in the paediatric population. The subjects were divided into three groups according to their age: 6 months to 6 years; 6 years to 10 years; and 10 years to 17 years. They were given 100 mg, 200 mg, or 300 mg of allopurinol, respectively (based on age) in a single oral dose. Maximum peak urinary orotic acid levels following ingestion of allopurinol were 13.0 (n = 14), 9.3 (n = 14), and 10.2 (n = 16) mumol/mmol creatinine in the three groups, respectively. In all children tested the peak orotic acid level was 3.1 +/- 2.7 mumol/mmol creatinine (mean +/- SD, n = 44). This allopurinol challenge test was also performed in six children with urea-cycle disorders, including five females with ornithine transcarbamylase (OTC) deficiency, all of whom demonstrated abnormally elevated levels of urinary orotic acid (peak levels of 26-134 mumol/mmol creatinine) following allopurinol ingestion.

we describe a new RP-HPLC assay to measure orotate concentration in urine. The method is rapid, sensitive and precise. It is particularly suitable for the diagnosis of inherited metabolic diseases and deranged orotate metabolism.

A new reversed-phase high-performance liquid chromatographic procedure for the determination of urinary orotate excretion is described. It is a selective, sensitive and rapid method, suitable for the differentiation of inherited metabolic diseases with abnormal orotate metabolism.