Protective role of amantadine in mitochondrial dysfunction and oxidative stress mediated by hepatitis C virus protein expression.

Amantadine is an antiviral and antiparkinsonian drug that has been evaluated in combination therapies against hepatitis C virus (HCV) infection. Controversial results have been reported concerning its efficacy, and its mechanism of action remains unclear. Data obtained in vitro suggested a role of amantadine in inhibiting HCV p7-mediated cation conductance. In keeping with the fact that mitochondria are responsible to ionic fluxes and that HCV infection impairs mitochondrial function, we investigated a potential role of amantadine in modulating mitochondrial function. Using a well-characterized inducible cell line expressing the full-length HCV polyprotein, we found that amantadine not only prevented but also rescued HCV protein-mediated mitochondrial dysfunction. Specifically, amantadine corrected (i) overload of mitochondrial Ca(2+); (ii) inhibition of respiratory chain activity and oxidative phosphorylation; (iii) reduction of membrane potential; and (iv) overproduction of reactive oxygen species. The effects of amantadine were observed within 15 min following drug administration and confirmed in Huh-7.5 cells transfected with an infectious HCV genome. These effects were also observed in cells expressing subgenomic HCV constructs, indicating that they are not mediated or only in part mediated by p7. Single organelle analyzes carried out on isolated mouse liver mitochondria demonstrated that amantadine induces hyperpolarization of the membrane potential. Moreover, amantadine treatment increased the calcium threshold required to trigger mitochondrial permeability transition opening. In conclusion, these results support a role of amantadine in preserving cellular bioenergetics and redox homeostasis in HCV-infected cells and unveil an effect of the drug which might be exploited for a broader therapeutic utilization.

Synthesis, characterization and kinetic studies on complex formed between amantadine hydrochloride and sodium molybdate at physiological pH

The title reaction was undertaken to establish the interaction between amantadine and molybdate at physiological pH. Identical FTIR spectra, TG-DTA curves and CHN data of the complexes formed from three solutions at pH 1.5, 7.4 and 8.0 indicate that the same complex was formed at all the three pHs. The FTIR spectrum shows shift in peaks corresponding to primary amino group of the drug due to coordination to molybdate. An octahedral geometry is assigned to the complex. The kinetics of the complexation has been studied at low concentrations of the reactants using UV-visible spectrophotometry. At pH 7.4, the initial rate varies linearly with [molybdate]. A plot of initial rate versus [drug] is linear passing through origin. These results indicate that the drug and molybdate react at pH 7.4 even at low concentrations. At pH 1.5, the rate increases linearly with increase in [drug] but decreases with [molybdate]. The effect of pH and ionic strength on the rate of the reaction has also been studied. A suitable mechanism has been proposed for the reaction. Reaction between the drug and molybdate even at low concentrations and the fact that the amino group of amantadine required to be free for its function as antiviral, is bound to molybdate in the complex suggests that simultaneous administration of the drug and molybdate supplements should be avoided.

A conserved basic loop in hepatitis C virus p7 protein is required for amantadine-sensitive ion channel activity in mammalian cells but is dispensable for localization to mitochondria

We previously identified the function of the hepatitis C virus (HCV) p7 protein as an ion channel in artificial lipid bilayers and demonstrated that this in vitro activity is inhibited by amantadine. Here we show that the ion channel activity of HCV p7 expressed in mammalian cells can substitute for that of influenza virus M2 in a cell-based assay. This was also the case for the p7 from the related virus, bovine viral diarrhoea virus (BVDV). Moreover, amantadine was shown to abrogate HCV p7 function in this assay at a concentration that specifically inhibits M2. Mutation of a conserved basic loop located between the two predicted trans-membrane alpha helices rendered HCV p7 non-functional as an ion channel. The intracellular localization of p7 was unaffected by this mutation and was found to overlap significantly with membranes associated with mitochondria. Demonstration of p7 ion channel activity in cellular membranes and its inhibition by amantadine affirm the protein as a target for future anti-viral chemotherapy.

Re-treatment of previous non-responders and relapsers to interferon plus ribavirin with peginterferon alfa-2a (40KD), ribavirin +/- amantadine in patients with chronic hepatitis C: randomized multicentre clinical trial

Introduction. A large number of patients with chronic hepatitis C have not been cured with interferon-based therapy. Therefore, we evaluated the efficacy of amantadine combined with the standard of care (pegylated interferon plus ribavirin) in patients who had not responded to or had relapsed after 24 weeks of treatment with conventional interferon plus ribavirin. Material and methods. Patients stratified by previous response (i.e., non-response or relapse) were randomized to 48 weeks of open-label treatment with peginterferon alfa-2a (401(D) 180 pg/week plus ribavirin 1,000/1,200 mg/day plus amantadine 200 mg/day (triple therapy), or the standard of care (peginterferon alfa-2a [40KD] plus ribavirin). Results. The primary outcome was sustained virological response (SVR), defined as undetectable hepatitis C virus RNA in serum (< 50 IU/mL) at end of follow-up (week 72). Among patients with a previous non-response, 12/53 (22.6%; 95% confidence interval [CI] 12.3-36.2%) randomized to triple therapy achieved an SVR compared with 16/52 (30.8%; 95% CI 18.7-45.1%) randomized to the standard of care. Among patients with a previous relapse 22/39 (56.4%; 95% CI 39.6-72.2%) randomized to triple therapy achieved an SVR compared with 23/38 (60.5%; 95% CI 43.4-76.0%) randomized to the standard of care. Undetectable HCV RNA (< 50 IU/mL) at week 12 had a high positive predictive value for SVR. A substantial proportion of non-responders and relapsers to conventional interferon plus ribavirin achieve an SVR when re-treated with peginterferon alfa-2a (40KD) plus ribavirin. Conclusion. Amantadine does not enhance SVR rates in previously treated patients with chronic hepatitis C and cannot be recommended in this setting.

Re-treatment of previous non-responders and relapsers to interferon plus ribavirin with peginterferon alfa-2a (40KD), ribavirin +/- amantadine in patients with chronic hepatitis C: randomized multicentre clinical trial

Introduction. A large number of patients with chronic hepatitis C have not been cured with interferon-based therapy. Therefore, we evaluated the efficacy of amantadine combined with the standard of care (pegylated interferon plus ribavirin) in patients who had not responded to or had relapsed after 24 weeks of treatment with conventional interferon plus ribavirin. Material and methods. Patients stratified by previous response (i.e., non-response or relapse) were randomized to 48 weeks of open-label treatment with peginterferon alfa-2a (401(D) 180 pg/week plus ribavirin 1,000/1,200 mg/day plus amantadine 200 mg/day (triple therapy), or the standard of care (peginterferon alfa-2a [40KD] plus ribavirin). Results. The primary outcome was sustained virological response (SVR), defined as undetectable hepatitis C virus RNA in serum (< 50 IU/mL) at end of follow-up (week 72). Among patients with a previous non-response, 12/53 (22.6%; 95% confidence interval [CI] 12.3-36.2%) randomized to triple therapy achieved an SVR compared with 16/52 (30.8%; 95% CI 18.7-45.1%) randomized to the standard of care. Among patients with a previous relapse 22/39 (56.4%; 95% CI 39.6-72.2%) randomized to triple therapy achieved an SVR compared with 23/38 (60.5%; 95% CI 43.4-76.0%) randomized to the standard of care. Undetectable HCV RNA (< 50 IU/mL) at week 12 had a high positive predictive value for SVR. A substantial proportion of non-responders and relapsers to conventional interferon plus ribavirin achieve an SVR when re-treated with peginterferon alfa-2a (40KD) plus ribavirin. Conclusion. Amantadine does not enhance SVR rates in previously treated patients with chronic hepatitis C and cannot be recommended in this setting.

Development and evaluation of a novel intranasal spray for the delivery of amantadine

The aim of this study was to develop and characterize an intranasal delivery system for amantadine hydrochloride (AMT). Optimal formulations consisted of a thermosensitive polymer Pluronic® 127 and either carboxymethyl cellulose or chitosan which demonstrated gel transition at nasal cavity temperatures (34 ± 1°C). Rheologically, the loss tangent (Tan δ) confirmed a 3-stage gelation phenomena at 34 ± 1°C and non-Newtonian behavior. Storage of optimized formulation carboxymethyl cellulose and optimal formulation chitosan at 4°C for 8 weeks resulted in repeatable release profiles at 34°C when sampled, with a Fickian mechanism earlier on but moving toward anomalous transport by week 8. Polymers (Pluronic® 127, carboxymethyl cellulose, and chitosan) demonstrated no significant cellular toxicity to human nasal epithelial cells up to 4 mg/mL and up to 1 mM for AMT (IC50: 4.5 ± 0.05 mM). Optimized formulation carboxymethyl cellulose and optimal formulation chitosan demonstrated slower release across an in vitro human nasal airway model (43%-44% vs 79 ± 4.58% for AMT). Using a human nasal cast model, deposition into the olfactory regions (potential nose-to-brain) was demonstrated on nozzle insertion (5 mm), whereas tilting of the head forward (15°) resulted in greater deposition in the bulk of the nasal cavity.

Genomic Signatures and Antiviral Drug Susceptibility Profile of A(H1N1)pdm09

Background: Genetic changes in influenza surface and internal genes can alter viral fitness and virulence. Mutation trend analysis and antiviral drug susceptibility profiling of A(H1N1)pdm09 viruses is essential for risk assessment of emergent strains and disease management. Objective: To profile genomic signatures and antiviral drug resistance of A(H1N1)pdm09 viruses and to discuss the potential role of mutated residues in human host adaptation and virulence. Study design: A(H1N1)pdm09 viruses circulating in Portugal during pandemic and post-pandemic periods and 2009/2010 season. Viruses were isolated in MDCK-SIAT1 cell culture and subjected to mutation analysis of surface and internal proteins, and to antiviral drug susceptibility profiling. Results: The A(H1N1)pdm09 strains circulating during the epidemic period in Portugal were resistant to amantadine. The majority of the strains were found to be susceptible to oseltamivir and zanamivir, with five outliers to neuraminidase inhibitors (NAIs) identified. Specific mutation patterns were detected within the functional domains of internal proteins PB2, PB1, PA, NP, NS1, M1 and NS2/NEP, which were common to all isolates and also some cluster-specific. Discussion: Modification of viral genome transcription, replication and apoptosis kinetics, changes in antigenicity and antiviral drug susceptibility are known determinants of virulence. We report several point mutations with putative roles in viral fitness and virulence, and discuss their potential to result in more virulent phenotypes. Monitoring of specific mutations and genetic patterns in influenza viral genes is essential for risk assessing emergent strains, disease epidemiology and public health implications.

Ataxias heredodegenerativas

Descripción de las ataxias heredodegenerativas con énfasis en la semiología general de este tipo de enfermedades y la fisiopatología de los grandes grupos de ataxias.

Structural, Electronic, and Vibrational Properties of Amino-adamantane and Rimantadine Isomers

We performed a first principles total energy investigation on the structural, electronic, and vibrational propel ties of adamantane molecules, functionalized with amine and ethanamine groups. We computed the vibrational signatures of amantadine and rimanadine isomers with the functional groups bonded to clinic:ill carbon sites By comparing Out results with recent infrared and Raman spectroscopic data, we discuss the possible presence of different isomers in experimental samples.

Case for diagnosis

Descreve-se caso clínico de paciente feminina adulta, portadora de doença de Parkinson em uso de amantadina que desenvolveu extenso quadro de livedo reticular nos membros e abdome após o início do medicamento. Discutem-se a semiotécnica diagnóstica do livedo reticular e seus diferenciais. Os autores salientam que a etiologia medicamentosa deva ser considerada no diagnóstico dos livedos reticulares.

Role of calcium, glutamate and NMDA in major depression and therapeutic application

Major depression is a common, recurrent mental illness that affects millions of people worldwide. Recently, a unique fast neuroprotective and antidepressant treatment effect has been observed by ketamine, which acts via the glutamatergic system. Hence, a steady accumulation of evidence supporting a role for the excitatory amino acid neurotransmitter (EAA) glutamate in the treatment of depression has been observed in the last years. Emerging evidence indicates that N-methyl-D-aspartate (NMDA), group 1 metabotropic glutamate receptor antagonists and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) agonists have antidepressant properties. Indeed, treatment with NMDA receptor antagonists has shown the ability to sprout new synaptic connections and reverse stress-induced neuronal changes. Based on glutamatergic signaling, a number of therapeutic drugs might gain interest in the future. Several compounds such as ketamine, memantine, amantadine, tianeptine, pioglitazone, riluzole, lamotrigine, AZD6765, magnesium, zinc, guanosine, adenosine aniracetam, traxoprodil (CP-101,606), MK-0657, GLYX-13, NRX-1047, Ro25-6981, LY392098, LY341495, D-cycloserine, D-serine, dextromethorphan, sarcosine, scopolamine, pomaglumetad methionil, LY2140023, LY404039, MGS0039, MPEP, 1-aminocyclopropanecarboxylic acid, all of which target this system, have already been brought up, some of them recently. Drugs targeting the glutamatergic system might open up a promising new territory for the development of drugs to meet the needs of patients with major depression.

A functionally defined model for the M2 proton channel of influenza A virus suggests a mechanism for its ion selectivity

The M2 protein from influenza A virus forms proton-selective channels that are essential to viral function and are the target of the drug amantadine. Cys scanning was used to generate a series of mutants with successive substitutions in the transmembrane segment of the protein, and the mutants were expressed in Xenopus laevis oocytes. The effect of the mutations on reversal potential, ion currents, and amantadine resistance were measured. Fourier analysis revealed a periodicity consistent with a four-stranded coiled coil or helical bundle. A three-dimensional model of this structure suggests a possible mechanism for the proton selectivity of the M2 channel of influenza virus.

The active oligomeric state of the minimalistic influenza virus M2 ion channel is a tetramer

The influenza A virus M2 integral membrane protein is an ion channel that permits protons to enter virus particles during uncoating of virions in endosomes and also modulates the pH of the trans-Golgi network in virus-infected cells. The M2 protein is a homo-oligomer of 97 residues, and analysis by chemical cross-linking and SDS/PAGE indicates M2 forms a tetramer. However, a higher order molecular form is sometimes observed and, thus, it is necessary to determine the active form of the molecule. This was done by studying the currents of oocytes that expressed mixtures of the wild-type M2 protein (epitope tagged) and the mutant protein M2-V27S, which is resistant to the inhibitor amantadine. The composition of mixed oligomers of the two proteins expressed at the plasma membrane of individual oocytes was quantified after antibody capture of the cell surface expressed molecules and it was found that the subunits mixed freely. When the ratio of wild-type to mutant protein subunits was 0.85:0.15, the amantadine sensitivity was reduced to 50% and for a ratio of 0.71:0.29 to 20%. These results are consistent with the amantadine-resistant mutant being dominant and the oligomeric state being a tetramer.