Rimantadine but not amantadine protects fischer rat embryo cells from transformation induced by 3-methylcholanthrene or benzo(a)pyrene

Summary The antiviral drugs amantadine hydrochloride and rimantadine hydrochloride were tested as to their oncogenic potential using a serial line of Fischer rat embryo cells that previously had been shown to be an accurate indicator of chemicals known to be oncogenic in animal studies. Neither compound was found to have transforming activity. At slightly toxic levels, rimantadine hydrochloride, but not amantadine hydrochloride, protected the same cell line from the transformation induced by the polycyclic hydrocarbons 3-methylcholanthrene and benzo(a)pyrene. This work was supported by Contract N01-CP-43240 within The Virus Cancer Program of the National Cancer Institute.     

Effect of amantadine on L-2-14C-dopa metabolism in parkinsonism

A metabolic study of the effects of amantadine hydrochloride on the fate of orally administered L-2-¹⁴C-dopa is described in three subjects with Parkinson's disease. Serum and urine distribution of radioactivity were determined in catecholamine, dopa, methoxydopa, and phenol carboxylic acid fractions prior to and after the administration of amantadine 100 mg daily for 4 weeks. Amantadine moderately decreased serum and urinary radioactivity during the first 2 hrs. Further, amantadine administration markedly decreased the urinary, but not serum, catecholamine fraction. Concomitantly, a two fold rise in urinary phenol carboxylic acids fraction from base line values was noted. It is concluded that amantadine may decrease extracerebral metabolism of levodopa and reduce the extent of its metabolism to its catecholamine metabolites.     

Mode of Action of the Antiviral Activity of Amantadine in Tissue Culture.

Hoffmann, C. E. (E. I. du Pont de Nemours & Co., Inc., Wilmington, Del.), E. M. Neumayer, R. F. Haff, and R. A. Goldsby. Mode of action of the antiviral activity of amantadine in tissue culture. J. Bacteriol. 90:623-628. 1965.-Amantadine hydrochloride has shown antiviral activity in tissue culture, in ovo, and in vivo. Experiments with it during the course of virus proliferation indicate that its antiviral activity is due to inhibition of virus penetration into the host cell. These studies indicate that amantadine hydrochloride is not virucidal at concentrations active in tissue culture. It does not block virus adsorption to host cells, nor does it affect the virus enzyme neuraminidase. In the presence of amantadine hydrochloride, virus adsorbed to susceptible cells remains at the cell surface in an infective state. An attempt to demonstrate high development of resistance to the antiviral action of amantadine hydrochloride in tissue culture has been unsuccessful.     

Amantadine-dyazide interaction.

To document an interaction between amantadine hydrochloride and Dyazide that had apparently produced amantadine toxicity, a patient was given amantadine alone for 1 week, followed by amantadine plus Dyazide for another week, under controlled conditions. A diuretic effect was observed after Dyazide was added to the regimen, but the urine amantadine excretion fell, and the drug''s plasma concentration increased. It was concluded that one or both of the components of Dyazide (hydrochlorothiazide and triamterene) reduce the clearance of amantadine and can produce higher plasma concentrations and toxic effects.     

Amantadine-HCl (Symmetrel) in the Management of Parkinson's Disease: A Double-Blind Cross-Over Study

A double-blind cross-over study was carried out in 54 patients with Parkinson''s disease to evaluate the efficacy of amantadine hydrochloride as compared to a lactose placebo in the management of this illness. Amantadine proved to be a useful and safe addition to the armamentarium when given in daily doses of 200 mg. Forty-eight per cent of patients experienced moderate to good results while 31% showed no measurable improvement. The quality of the improvement was inferior to that obtained with levodopa, but the side effects were fewer. The study could not demonstrate a useful synergistic action between the two drugs, nor could the response to amantadine be used to predict that with levodopa. On the other hand, the addition of amantadine was useful in a few instances where optimal therapeutic doses of levodopa could not be given because of side effects. The mechanism of action of amantadine is still conjectural, but there is strong evidence to indicate some interaction with central dopamine metabolism.     

Specific structural alteration of the influenza haemagglutinin by amantadine.

Amantadine hydrochloride specifically blocks the release of virus particles from H7 influenza virus infected cells. This appears to be the direct consequence of an amantadine induced change in the haemagglutinin (HA) to its low pH conformation. The effect is indirect and mediated via interaction of the drug with the M2 protein since mutants altered in this component alone are insensitive to amantadine. The timing of drug action, some 15-20 min after synthesis, and its coincidence with proteolytic cleavage indicates that the modifications to HA occur late during transport but prior to insertion into the plasma membrane. Reversal by mM concentrations of amines and 0.1 microM monensin indicates that amantadine action causes a reduction in intravesicular pH which triggers the conformational change in HA. We conclude, therefore, that the function of M2 inhibited by amantadine is involved in counteracting the acidity of vesicular compartments of the exocytic pathway in infected cells and is important in protecting the structural integrity of the acid-sensitive glycoprotein.     

Amantadine Ameliorates Dopamine-Releasing Deficits and Behavioral Deficits in Rats after Fluid Percussion Injury

Aims

To investigate the role of dopamine in cognitive and motor learning skill deficits after a traumatic brain injury (TBI), we investigated dopamine release and behavioral changes at a series of time points after fluid percussion injury, and explored the potential of amantadine hydrochloride as a chronic treatment to provide behavioral recovery.

Materials and Methods

In this study, we sequentially investigated dopamine release at the striatum and behavioral changes at 1, 2, 4, 6, and 8 weeks after fluid percussion injury. Rats subjected to 6-Pa cerebral cortical fluid percussion injury were treated by using subcutaneous infusion pumps filled with either saline (sham group) or amantadine hydrochloride, with a releasing rate of 3.6mg/kg/hour for 8 weeks. The dopamine-releasing conditions and metabolism were analyzed sequentially by fast scan cyclic voltammetry (FSCV) and high-pressure liquid chromatography (HPLC). Novel object recognition (NOR) and fixed-speed rotarod (FSRR) behavioral tests were used to determine treatment effects on cognitive and motor deficits after injury.

Results

Sequential dopamine-release deficits were revealed in 6-Pa-fluid-percussion cerebral cortical injured animals. The reuptake rate (tau value) of dopamine in injured animals was prolonged, but the tau value became close to the value for the control group after amantadine therapy. Cognitive and motor learning impairments were shown evidenced by the NOR and FSRR behavioral tests after injury. Chronic amantadine therapy reversed dopamine-release deficits, and behavioral impairment after fluid percussion injuries were ameliorated in the rats treated by using amantadine-pumping infusion.

Conclusion

Chronic treatment with amantadine hydrochloride can ameliorate dopamine-release deficits as well as cognitive and motor deficits caused by cerebral fluid-percussion injury.     

Removal of amantadine hydrochloride by dialysis in patients with renal insufficiency.

Two patients with Parkinson''s disease and renal insufficiency had excessively high concentrations of amantadine hydrochloride in the blood. The amounts of the drug removed by hemodialysis and peritoneal dialysis were small. However, since extrarenal elimination is negligible in such patients, frequently repeated dialysis may be required to remove the drug.     

Influenza virus M2 protein has ion channel activity.

The influenza virus M2 protein was expressed in Xenopus laevis oocytes and shown to have an associated ion channel activity selective for monovalent ions. The anti-influenza virus drug amantadine hydrochloride significantly attenuated the inward current induced by hyperpolarization of oocyte membranes. Mutations in the M2 membrane-spanning domain that confer viral resistance to amantadine produced currents that were resistant to the drug. Analysis of the currents of these altered M2 proteins suggests that the channel pore is formed by the transmembrane domain of the M2 protein. The wild-type M2 channel was found to be regulated by pH. The wild-type M2 ion channel activity is proposed to have a pivotal role in the biology of influenza virus infection.     

Treatment of Acute Herpes Zoster with Amantadine Hydrochloride (Symmetrel)

A double-blind, placebo-controlled trial of amantadine hydrochloride (Symmetrel) in acute herpes zoster (shingles) was carried out in 100 patients in general practice. The cases were serologically proved. There was no difference in duration of pain between the drug and placebo groups when pain disappeared during the 28 days'' observation period. However, pain lasted more than 28 days in a significantly greater proportion of patients receiving placebo than of those on amantadine. Patients with pain after the 28-day observation period were significantly older than those whose pain disappeared during the study. The drug had no effect on rate of healing or appearance of new lesions.     

Susceptibility of influenza A viruses to amantadine is influenced by the gene coding for M protein.

Influenza A virus recombinants derived from "resistant" and "sensitive" parental viruses were examined for susceptibility to inhibition by amantadine. Correlation of gene constellation and amantadine susceptibility revealed that the gene coding for M protein influences sensitivity or resistance to amantadine. All recombinants which derived an M protein from an amantadine-resistant parent were found to be resistant to amantadine. All amantadine-sensitive recombinants derived an M gene from the amantadine-sensitive parent. However, a few amantadine-resistant recombinants which derived an M gene from the sensitive parent were also isolated, suggesting that the expression of amantadine sensitivity in these recombinants may be influenced by other genes.     

Effects of amantadine on the dynamics of membrane-bound influenza A M2 transmembrane peptide studied by NMR relaxation

The molecular motions of membrane proteins in liquid-crystalline lipid bilayers lie at the interface between motions in isotropic liquids and in solids. Specifically, membrane proteins can undergo whole-body uniaxial diffusion on the microsecond time scale. In this work, we investigate the ¹H rotating-frame spin-lattice relaxation (T _1ρ) caused by the uniaxial diffusion of the influenza A M2 transmembrane peptide (M2TMP), which forms a tetrameric proton channel in lipid bilayers. This uniaxial diffusion was proved before by ²H, ¹⁵N and ¹³C NMR lineshapes of M2TMP in DLPC bilayers. When bound to an inhibitor, amantadine, the protein exhibits significantly narrower linewidths at physiological temperature. We now investigate the origin of this line narrowing through temperature-dependent ¹H T _1ρ relaxation times in the absence and presence of amantadine. Analysis of the temperature dependence indicates that amantadine decreases the correlation time of motion from 2.8 ± 0.9 μs for the apo peptide to 0.89 ± 0.41 μs for the bound peptide at 313 K. Thus the line narrowing of the bound peptide is due to better avoidance of the NMR time scale and suppression of intermediate time scale broadening. The faster diffusion of the bound peptide is due to the higher attempt rate of motion, suggesting that amantadine creates better-packed and more cohesive helical bundles. Analysis of the temperature dependence of $ { \ln }\left( {T_{1\rho }^{ - 1} } \right) $ indicates that the activation energy of motion increased from 14.0 ± 4.0 kJ/mol for the apo peptide to 23.3 ± 6.2 kJ/mol for the bound peptide. This higher activation energy indicates that excess amantadine outside the protein channel in the lipid bilayer increases the membrane viscosity. Thus, the protein-bound amantadine speeds up the diffusion of the helical bundles while the excess amantadine in the bilayer increases the membrane viscosity.     

Protocatechuic Acid,a Novel Active Substance against Avian Influenza Virus H9N2 Infection

Influenza virus H9N2 subtype has triggered co-infection with other infectious agents, resulting in huge economical losses in the poultry industry. Our current study aims to evaluate the antiviral activity of protocatechuic acid (PCA) against a virulent H9N2 strain in a mouse model. 120 BALB/c mice were divided into one control group, one untreated group, one 50 mg/kg amantadine hydrochloride-treated group and three PCA groups treated 12 hours post-inoculation with 40, 20 or 10 mg/kg PCA for 7 days. All the infected animals were inoculated intranasally with 0.2 ml of a A/Chicken/Hebei/4/2008(H9N2) inoculum. A significant body weight loss was found in the 20 mg/kg and 40 mg/kg PCA-treated and amantadine groups as compared to the control group. The 14 day survivals were 94.4%, 100% and 95% in the PCA-treated groups and 94.4% in the amantadine hydrochloride group, compared to less than 60% in the untreated group. Virus loads were less in the PCA-treated groups compared to the amantadine-treated or the untreated groups. Neutrophil cells in BALF were significantly decreased while IFN-γ, IL-2, TNF-α and IL-6 decreased significantly at days 7 in the PCA-treated groups compared to the untreated group. Furthermore, a significantly decreased CD4+/CD8+ ratio and an increased proportion of CD19 cells were observed in the PCA-treated groups and amantadine-treated group compared to the untreated group. Mice administered with PCA exhibited a higher survival rate and greater viral clearance associated with an inhibition of inflammatory cytokines and activation of CD8+ T cell subsets. PCA is a promising novel agent against bird flu infection in the poultry industry.     

Fusion mutants of the influenza virus hemagglutinin glycoprotein

The influenza virus hemagglutinin (HA) mediates viral entry into cells by a low pH induced membrane-fusion event in endosomal vesicles. Mutant viruses with altered pH dependence for both hemolysis and the HA conformational change required for fusion were selected for their ability to grow in cells treated with amantadine hydrochloride, which raises the endosomal pH. The amino acid sequence and three-dimensional location of 19 substitutions on the HA are reported. The mutations fall into two groups, one that results in the destabilization of the pH 7.0 location of the hydrophobic N-terminal HA2 peptide, and a second that results in the alteration of intersubunit contacts, suggesting a large distortion or disruption of these contacts in the "fusion-active" conformation.     

二甲双胍对胶质母细胞瘤细胞的抑制作用研究

为了探究二甲双胍对不同胶质母细胞瘤U87细胞、GL261细胞及C6细胞增殖的影响,选取小鼠GBM细胞GL261细胞系、大鼠GBM细胞C6细胞系及人源GBM细胞U87MG细胞系,使用二甲双胍处理,通过CCK-8法检测细胞增殖活性;细胞实时荧光检测细胞凋亡水平;平板克隆实验检测GBM细胞克隆形成能力;CCK-L法检测胞内ATP水平;Western blot检测Akt及其磷酸化水平。结果显示,与对照组相比,随着作用浓度增加,二甲双胍显著抑制GBM细胞增殖活性,影响细胞形态;与对照组相比,同一作用浓度下,二甲双胍提高了GBM细胞凋亡水平,抑制了GBM细胞克隆形成能力,降低了GBM胞内ATP的产生;二甲双胍处理24 h后,GBM细胞内p-Akt表达显著下调,Akt无明显变化。结果表明,二甲双胍在体外可抑制多种GBM细胞的增殖、克隆,降低胞内ATP水平,其机制可能与Akt磷酸化水平相关,研究结果为进一步探索二甲双胍对胶质母细胞瘤的作用机制提供了体外研究理论基础。     

pH-dependent tetramerization and amantadine binding of the transmembrane helix of M2 from the influenza A virus

The M2 proton channel from the influenza A virus is a small protein with a single transmembrane helix that associates to form a tetramer in vivo. This protein forms proton-selective ion channels, which are the target of the drug amantadine. Here, we propose a mechanism for the pH-dependent association, and amantadine binding of M2, based on studies of a peptide representing the M2 transmembrane segment in dodecylphosphocholine micelles. Using analytical ultracentrifugation, we find that the sedimentation curves for the peptide depend on its concentration in the micellar phase. The data are well-described by a monomer-tetramer equilibrium, and the binding of amantadine shifts the monomer-tetramer equilibrium toward tetrameric species. Both tetramerization and the binding of amantadine lead to increases in the magnitude of the ellipticity at 223 nm in the circular dichroism spectrum of the peptide. The tetramerization and binding of amantadine are more favorable at elevated pH, with a pK(a) that is assigned to a His side chain, the only ionizable residue within the transmembrane helix. Our results, interpreted quantitatively in terms of a reversible monomer and tetramer protonation equilibrium model, suggest that amantadine competes with protons for binding to the deprotonated tetramer, thereby stabilizing the tetramer in a slightly altered conformation. This model accounts for the observed inhibition of proton flux by amantadine. Additionally, our measurements suggest that the M2 tetramer is substantially protonated at neutral pH and that both singly and doubly protonated states could be involved in M2's proton conduction at more acidic pHs.     

Characterization of inhibition of M2 ion channel activity by BL-1743, an inhibitor of influenza A virus.

The influenza A virus M2 integral membrane protein has ion channel activity that can be inhibited by the antiviral drug amantadine. Recently, a spirene-containing compound, BL-1743 (2-[3-azaspiro (5,5)undecanol]-2-imidazoline), that inhibits influenza virus growth was identified (S. Kurtz, G. Lao, K. M. Hahnenberger, C. Brooks, O. Gecha, K. Ingalls, K.-I. Numata, and M. Krystal, Antimicrob. Agents Chemother. 39:2204-2209, 1995). We have examined the ability of BL-1743 to inhibit the M2 ion channel when expressed in oocytes of Xenopus laevis. BL-1743 inhibition is complete as far as can be measured by electrophysiological methods and is reversible, with a reverse reaction rate constant of 4.0 x 10(-3) s(-1). In contrast, amantadine inhibition is irreversible within the time frame of the experiment. However, BL-1743 inhibition and amantadine inhibition have similar properties. The majority of isolated influenza viruses resistant to BL-1743 are also amantadine resistant. In addition, all known amino acid changes which result in amantadine resistance also confer BL-1743 resistance. However, one BL-1743-resistant virus isolated, designated M2-I35T, contained the change Ile-35-->Thr. This virus is >70-fold more resistant to BL-1743 and only 10-fold more resistant to amantadine than the wild-type virus. When the ion channel activity of M2-I35T was examined in oocytes, it was found that M2-I35T is BL-1743 resistant but is reversibly inhibited by amantadine. These findings suggest that these two drugs interact differently with the M2 protein transmembrane pore region.