Keel venom: Rhabdophis subminiatus (Red-Necked Keelback) venom pathophysiologically affects diverse blood clotting pathways.

Venoms are evolutionary novelties that have real-world implications due to their impact upon human health. However, relative to the abundant studies of elapid and viperid snake venoms, fewer investigations have been undertaken on those of rear-fanged snakes as they are more problematic for obtaining venom. While most rear-fanged venomous snakes are not considered to be of great medical importance, several species are capable of producing fatalities. Most notable among these are snakes from the genus Rhabdophis, the Asian "keelback" snakes. Prior work have described potent procoagulant toxicity suggesting Factor X and prothrombin activation, but did not investigate the ability to activate other clotting factors. Here we show that in addition to activating both Factor X and prothrombin (with prothrombin twice that of FX), the venom of Rhabdophis subminiatus is able to more potently activate Factor VII (ten times that of prothrombin), while also activating FXII and FIX equipotently to prothrombin, and with FXI also activated but at a much lower level. The ability to activate FVII represents a third convergent evolution of this trait. The Australian elapid clade of [Oxyuranus (taipans) + Pseudonaja (brown snakes)] was the first identified to have evolved this trait. and only recently was it shown to be independently present in another lineage (the Central American viperid species Porthidium volcanicum). In addition, the abilities to activate FXI and FXII are also convergent between R. subminiatus and P. volcanicum, but with R. subminiatus being much more potent. By testing across amphibian, avian, and mammalian plasmas we demonstrate that the venom is potently procoagulant across diverse plasma types. However, consistent with dietary preference, R. subminiatus venom was most potent upon amphibian plasma. While a Rhabdophis antivenom is produced in Japan to treat R. tigrinus envenomings, it is scarce even within Japan and is not exported. As this genus is very wide-ranging in Asia, alternate treatment options are in need of development. Hence we tested the ability of candidate, broad-spectrum enzyme inhibitors to neutralize R. subminiatus venom: marimastat was more effective than prinomastat but both marimastat and prinomastat were significantly more effective than DMPS (2,3-Dimercapto-1-propanesulfonic acid). The findings of this study shed light on the evolution of these fascinating rear-fanged snakes as well as explored their systemic effects upon blood coagulation and point to potential treatment options for the rare, but potentially lethal encounters.

[Study on the difference of curative effect of conventional mercury displacement treatment on mercury in brain and kidney].

Objective: To explore the expulsion effect of sodium dimercaptopropanesulfonate (DMPS) on mercury in different organs of mercury poisoning and the therapeutic effect of glutathione (GSH) combined with antioxidant therapy on mercury poisoning. Methods: In February 2019, 50 SPF male SD rats were randomly divided into 5 groups, 10 rats in each group: A (saline negative control group) , B (HgCL2 positive control group) , treatment group (C: intramuscular injection of DMPS 15 mg/kg treatment, D: intramuscular injection of DMPS30 mg/kg treatment, E: intramuscular injection of DMPS 15 mg/kg and intraperitoneal injection of GSH200 mg/kg treatment) . Rats in group B, C, D and E were subcutaneously injected with mercury chloride solution (1 mg/kg) to establish a rat model of subacute mercury poisoning kidney injury. Rats in group A were subcutaneously injected with normal saline. After the establishment of the model, rats in the treatment group were injected with DMPS and GSH. Rats in group A and group B were injected with normal saline. At 21 d (treatment 7 d) and 28 d (treatment 14 d) after exposure, urine and blood samples of 5 rats in each group were collected. Blood biochemistry, urine mercury, urine microalbumin and mercury content in renal cortex, cerebral cortex and cerebellum were detected. Results: After exposure to mercury, the contents of mercury in renal cortex, cerebrum and cerebellum of rats in group B, C, D and E increased, and urine microalbumin increased. Pathology showed renal tubular injury and renal interstitial inflammation. Compared with group B, urinary mercury and renal cortex mercury in group C, D and E decreased rapidly after DMPS treatment, and there was no significant decrease in mercury levels in cerebellum and cerebral cortex of rats, accompanied by transient increase in urinary albumin after DMPS treatment (P<0.05) ; the renal interstitial inflammation in group E was improved after GSH treatment. There was a positive correlation between urinary mercury and the contents of mercury in renal cortex, cerebral cortex and cerebellum (r=0.61, 0.47, 0.48, P<0.05) . Conclusion: DMPS mercury expulsion treatment can significantly reduce the level of metal mercury in the kidney, and there is no significant change in the level of metal mercury in the cortex and cerebellum.

Drug Repurposing of the Unithiol: Inhibition of Metallo-ß-Lactamases for the Treatment of Carbapenem-Resistant Gram-Negative Bacterial Infections.

The increasing antibiotic resistance is a clinical problem worldwide. Numerous Gram-negative bacteria have already become resistant to the most widely used class of antibacterial drugs, ß-lactams. One of the main mechanisms is inactivation of ß-lactam antibiotics by bacterial ß-lactamases. Appearance and spread of these enzymes represent a continuous challenge for the clinical treatment of infections and for the design of new antibiotics and inhibitors. Drug repurposing is a prospective approach for finding new targets for drugs already approved for use. We describe here the inhibitory potency of known detoxifying antidote 2,3-dimercaptopropane-1-sulfonate (unithiol) against metallo-ß-lactamases. Unithiol acts as a competitive inhibitor of meropenem hydrolysis by recombinant metallo-ß-lactamase NDM-1 with the KI of 16.7 µM. It is an order of magnitude lower than the KI for l-captopril, the inhibitor of angiotensin-converting enzyme approved as a drug for the treatment of hypertension. Phenotypic methods demonstrate that the unithiol inhibits natural metallo-ß-lactamases NDM-1 and VIM-2 produced by carbapenem-resistant K. pneumoniae and P. aeruginosa bacterial strains. The 3D full atom structures of unithiol complexes with NDM-1 and VIM-2 are obtained using QM/MM modeling. The thiol group is located between zinc cations of the active site occupying the same place as the catalytic hydroxide anion in the enzyme-substrate complex. The sulfate group forms both a coordination bond with a zinc cation and hydrogen bonds with the positively charged residue, lysine or arginine, responsible for proper orientation of antibiotics upon binding to the active site prior to hydrolysis. Thus, we demonstrate both experimentally and theoretically that the unithiol is a prospective competitive inhibitor of metallo-ß-lactamases and it can be utilized in complex therapy together with the known ß-lactam antibiotics.

Venom-Induced Blood Disturbances by Palearctic Viperid Snakes, and Their Relative Neutralization by Antivenoms and Enzyme-Inhibitors.

Palearctic vipers are medically significant snakes in the genera Daboia, Macrovipera, Montivipera, and Vipera which occur throughout Europe, Central Asia, Near and Middle East. While the ancestral condition is that of a small-bodied, lowland species, extensive diversification has occurred in body size, and niche specialization. Using 27 venom samples and a panel of in vitro coagulation assays, we evaluated the relative coagulotoxic potency of Palearctic viper venoms and compared their neutralization by three antivenoms (Insoserp Europe, VIPERFAV and ViperaTAb) and two metalloprotease inhibitors (prinomastat and DMPS). We show that variation in morphology parallels variation in the Factor X activating procoagulant toxicity, with the three convergent evolutions of larger body sizes (Daboia genus, Macrovipera genus, and Vipera ammodytes uniquely within the Vipera genus) were each accompanied by a significant increase in procoagulant potency. In contrast, the two convergent evolutions of high altitude specialization (the Montivipera genus and Vipera latastei uniquely within the Vipera genus) were each accompanied by a shift away from procoagulant action, with the Montivipera species being particularly potently anticoagulant. Inoserp Europe and VIPERFAV antivenoms were both effective against a broad range of Vipera species, with Inoserp able to neutralize additional species relative to VIPERFAV, reflective of its more complex antivenom immunization mixture. In contrast, ViperaTAb was extremely potent in neutralizing V. berus but, reflective of this being a monovalent antivenom, it was not effective against other Vipera species. The enzyme inhibitor prinomastat efficiently neutralized the metalloprotease-driven Factor X activation of the procoagulant venoms. In contrast, DMPS (2,3-dimercapto-1-propanesulfonic acid), which as been suggested as another potential treatment option in the absence of antivenom, DMPS failed against all venoms tested. Overall, our results highlight the evolutionary variations within Palearctic vipers and help to inform clinical management of viper envenomation.

A study of susceptibility-weighted imaging in patients with Wilson disease during the treatment of metal chelator.

OBJECTIVE: A randomized-controlled trial comparing study of the changes in brain sensitive-weighted imaging (SWI) of Wilson disease (WD) patients during the treatment with metal chelator was done. METHODS: 100 untreated WD patients (80 cases of cerebral type, 20 cases of hepatic type, age 20.13 ± 9.12 years old) and 20 normal controls were selected. Neurological symptoms were scored using the modified Young scale. Liver function tests and copper indices were collected. All study objects received SWI test of the brain. The values of corrected phase (CP) were calculated on SWI. Cerebral-type WD patients were treated with D-penicillamine (DPA) (group 1) or Dimercaptopropane Sulfonate (DMPS) + Dimercaptosuccinic Acid (DMSA) (group 2). Hepatic-type WD patients were treated with DPA (group 3). All patients received annual neurological symptom score, liver function, copper indices, and SWI examination. RESULTS: At the first year of treatment, score of the modified Young scale in group 2 was lower than that in group 1 (P = 0.023) and lower than that before treatment (P = 0.040). After 2 years of treatment, the score of the modified Young scale in group 1 was lower than that before treatment (P = 0.012). At the second year after treatment, the urinary copper in group 2 was higher than that in group 1 (P = 0.014). Urinary copper was maintained at 200 µg/day in group 1 and 300 µg/day in group 2 after 3 years of treatment. At the first year of treatment, serum copper in group 1 was lower than that in group 2 (P = 0.032). At the first year of treatment, CP values of the pallidum and substantia nigra in group 2 were higher than those in group 1 (P = 0.026, 0.040). At the second year of treatment, CP value of substantia nigra in group 2 was higher than that in group 1 (P = 0.037). After 3 years of treatment, there was no difference in CP values between WD patients and normal controls. CONCLUSIONS: Therapy with DMPS and DMSA improves neurological symptoms of WD patients more quickly and leads to less aggravation, compared with therapy with DPA. The metal content in the brain of WD patients was at a low level after 3 years of treatment. DMPS and DMSA can remove metal from brain tissue faster than DPA.

Arsenic Toxicity: Molecular Targets and Therapeutic Agents.

: High arsenic (As) levels in food and drinking water, or under some occupational conditions, can precipitate chronic toxicity and in some cases cancer. Millions of people are exposed to unacceptable amounts of As through drinking water and food. Highly exposed individuals may develop acute, subacute, or chronic signs of poisoning, characterized by skin lesions, cardiovascular symptoms, and in some cases, multi-organ failure. Inorganic arsenite(III) and organic arsenicals with the general formula R-As2+ are bound tightly to thiol groups, particularly to vicinal dithiols such as dihydrolipoic acid (DHLA), which together with some seleno-enzymes constitute vulnerable targets for the toxic action of As. In addition, R-As2+-compounds have even higher affinity to selenol groups, e.g., in thioredoxin reductase that also possesses a thiol group vicinal to the selenol. Inhibition of this and other ROS scavenging seleno-enzymes explain the oxidative stress associated with arsenic poisoning. The development of chelating agents, such as the dithiols BAL (dimercaptopropanol), DMPS (dimercapto-propanesulfonate) and DMSA (dimercaptosuccinic acid), took advantage of the fact that As had high affinity towards vicinal dithiols. Primary prevention by reducing exposure of the millions of people exposed to unacceptable As levels should be the prioritized strategy. However, in acute and subacute and even some cases with chronic As poisonings chelation treatment with therapeutic dithiols, in particular DMPS appears promising as regards alleviation of symptoms. In acute cases, initial treatment with BAL combined with DMPS should be considered.

Dimercapto-1-propanesulfonic acid (DMPS) induces metaphase II mouse oocyte deterioration.

In light of the recent lead contamination of the water in Flint, Michigan and its potential adverse outcomes, much research and media attention has turned towards the safety profile of commonly used chelators. Dimercapto-1-propanesulfonic acid (DMPS) typically used in the treatment of lead, mercury and arsenic poisoning also displays a high affinity towards transition metals such as zinc and copper, essential for biological functioning. It is given in series of dosages (0.2-0.4g/day) over a long period, and has the ability to enter cells. In this work, we investigated the mechanism through which increasing concentrations of DMPS alter oocyte quality as judged by changes in microtubule morphology (MT) and chromosomal alignment (CH) of metaphase II mice oocyte. The oocytes were directly exposed to increasing concentration of DMPS (10, 25, 50, 100 and 300µM) for four hours (time of peak plasma concentration after administration) and reactive oxygen species (mainly hydroxyl radical and superoxide) and zinc content were measured. This data showed DMPS plays an important role in deterioration of oocyte quality through a mechanism involving zinc deficiency and enhancement of reactive oxygen species a major contributor to oocyte damage. Our current work, for the first time, demonstrates the possibility of DMPS to negatively impact fertility. This finding can not only help in counseling reproductive age patients undergoing such treatment but also in the development of potential therapies to alleviate oxidative damage and preserve fertility in people receiving heavy metal chelators.

The effects of 2,3-dimercapto-1-propanesulfonic acid (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) on the nephrotoxicity in the mouse during repeated cisplatin (CDDP) treatments.

Previously, we reported that specific lower dose of sodium 2,3-dimercapto-1-propanesulfonic acid (DMPS) which is an antidote to heavy metal intoxication, inversely enhanced cisplatin (CDDP)-induced antitumor activity to S-180 cell-bearing mouse. This activity was only weak with meso-2,3-dimercaptosuccinic acid (DMSA), however. This study investigated the effects of lower doses of DMPS or DMSA on the nephrotoxicity and kinetics of CDDP. Kidney and blood isolated from female mice which received CDDP with or without DMPS or DMSA once daily for 4 days were provided for measuring levels of blood urea nitrogen (BUN) and transporter proteins (OCT2: organic cation transporter; MATE1: multidrug and toxin extrusion) mRNA, and CDDP-originated platinum, and TUNEL staining of renal tubular cells. DMPS or DMSA reduced effectively CDDP-induced BUN, and caused a moderate reduction of platinum in kidney. Additionally, both dimercapto-compounds restored the CDDP-reduced mRNA levels of transporter proteins (OCT2 and MATE1), and apparently suppressed the CDDP-induced apoptosis. These results suggest that DMPS, as well as DMSA, at approximate 17-fold dose (µmol/kg) of CDDP, has an enough potential to reverse the CDDP nephrotoxicity, and concomitant use of DMPS considering both dose and timing for administration is potentially useful for preventing nephrotoxicity and enhancing antitumor activity during CDDP chemotherapy.

Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus.

Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N',N'-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin.

Amine oxidases as important agents of pathological processes of rhabdomyolysis in rats.

In this study we have tested an idea on the important role of amine oxidases (semicarbazide-sensitive amine oxidase, diamine oxidase, polyamine oxidase) as an additional source of oxidative/carbonyl stress under glycerol-induced rhabdomyolysis, since the enhanced formation of reactive oxygen species and reactive carbonyl species in a variety of tissues is linked to various diseases. In our experiments we used the sensitive fluorescent method devised for estimation of amine oxidases activity in the rat kidney and thymus as targeted organs under rhabdomyolysis. We have found in vivo the multiple rises in activity of semicarbazide-sensitive amine oxidase, diamine oxidase, polyamine oxidase (2-4.5 times) in the corresponding cell fractions, whole cells or their lysates at the 3-6th day after glycerol injection. Aberrant antioxidant activities depended on rhabdomyolysis stage and had organ specificity. Additional treatment of animals with metal chelator 'Unithiol' adjusted only the activity of antioxidant enzymes but not amine oxidases in both organs. Furthermore the in vitro experiment showed that Fenton reaction (hydrogen peroxide in the presence of iron) products alone had no effect on semicarbazide-sensitive amine oxidase activity in rat liver cell fraction whereas supplementation with methylglyoxal resulted in its significant 2.5-fold enhancement. Combined action of the both agents had additive effect on semicarbazide-sensitive amine oxidase activity. We can assume that biogenic amine and polyamine catabolism by amine oxidases is upregulated by oxidative and carbonyl stress factors directly under rhabdomyolysis progression, and the increase in catabolic products concentration contributes to tissue damage in glycerol-induced acute renal failure and apoptosis stimulation in thymus.

Nanoparticles modulate autophagic effect in a dispersity-dependent manner.

Autophagy plays a key role in human health and disease, especially in cancer and neurodegeneration. Many autophagy regulators are developed for therapy. Diverse nanomaterials have been reported to induce autophagy. However, the underlying mechanisms and universal rules remain unclear. Here, for the first time, we show a reliable and general mechanism by which nanoparticles induce autophagy and then successfully modulate autophagy via tuning their dispersity. Various well-designed univariate experiments demonstrate that nanomaterials induce autophagy in a dispersity-dependent manner. Aggregated nanoparticles induce significant autophagic effect in comparison with well-dispersed nanoparticles. As the highly stable nanoparticles may block autophagic degradation in autolysosomes, endocytosis and intracellular accumulation of nanoparticles can be responsible for this interesting phenomenon. Our results suggest dispersity-dependent autophagic effect as a common cellular response to nanoparticles, reveal the relationship between properties of nanoparticles and autophagy, and offer a new alternative way to modulate autophagy.

[Immune homeostasis impairment in acute carbon tetrachloride intoxicated rats corrected by administration of tocopherol acetate and unithiol].

The results of experiments on noninbred albino rats showed that the acute intoxication with carbon tetrachloride (CT) at a dose of 1 LD50 reduced the parameters of cellular immune response and function of Th1 cells more significantly than the levels of humoral immune response and Th2-lymphocyte function, decreases the blood content of immunoregulatory cytokines IFN-g, IL-2, IL-4 and anti-inflammatory cytokine IL-13, while not changing the concentration of anti-inflammatory cytokine IL-10 and increasing the concentration of pro-inflammatory cytokine IL-6. The application of unithiol, tocopherol acetate, and combinations partially restores the parameters examined. The combined effects of drugs during intoxication with CT does not exceed their separate action.

Inhibitory mechanism of dimercaptopropanesulfonic acid (DMPS) in the cellular biomethylation of arsenic.

Dimercaptopropanesulfonic acid (DMPS) has been approved for the treatment of arsenic poisoning through promoting arsenic excretion and modulating arsenic species. To clarify how DMPS regulates the excretion of arsenic species, we investigated the effects of DMPS on the biomethylation of arsenite (As(3+)) in HepG2 cells. In the experiments, we found that DMPS at low concentrations dramatically decreased the content of arsenic in HepG2 cells and inhibited the cellular methylation of As(3+). Three aspects, the expression of human arsenic (III) methyltransferase (hAS3MT), the accumulation of cellular reactive oxygen species (ROS) and the in vitro enzymatic methylation of arsenic, were considered to explain the reasons for the inhibition of DMPS in arsenic metabolism. The results suggested that DMPS competitively coordinated with As(3+) and monomethylarsonous acid (MMA(3+)) to inhibit the up-regulation of arsenic on the expression of hAS3MT and block arsenic involving in the enzymatic methylation. Moreover, DMPS eliminated arsenic-induced accumulation of ROS, which might contribute to the antidotal effects of DMPS on arsenic posing.

Luminal transport of thiol S-conjugates of methylmercury in isolated perfused rabbit renal proximal tubules.

Lumen-to-cell transport, cellular accumulation, and toxicity of L-cysteine (Cys), glutathione (GSH) and N-acetylcysteine (NAC) S-conjugates of methylmercury (CH(3)Hg(+)) were evaluated in isolated, perfused rabbit proximal tubular segments. When these conjugates were perfused individually through the lumen of S(2) segments of the proximal tubule it was found that Cys-S-CH(3)Hg and GSH-S-CH(3)Hg were transported avidly, while NAC-S-CH(3)Hg was transported minimally. In addition, 95% of the (203)Hg taken up by the tubular cells was associated with precipitable proteins of the tubule, while very little was found in the acid-soluble cytosol. No visual cellular pathological changes were observed during 30min of study. Luminal uptake of Cys-S-CH(3)Hg was temperature-dependent and inhibited significantly by the amino acids L-methionine and l-cystine. Rates of luminal uptake of GSH-S-CH(3)Hg were twice as great as that of Cys-S-CH(3)Hg and uptake was inhibited significantly (74%) by the presence of acivicin. When 2,3-bis(sulfanyl)propane-1-sulfonate (DMPS) was added to the bathing or luminal fluid, luminal uptake of Cys-S-CH(3)Hg was diminished significantly. Overall, our data indicate that Cys-S-CH(3)Hg is likely a transportable substrate of one or more amino acid transporters (such as system B(0,+) and system b(0,+)) involved in luminal absorption of L-methionine and L-cystine along the renal proximal tubule. In addition, GSH-S-CH(3)Hg appears to be degraded enzymatically to Cys-S-CH(3)Hg, which can then be taken up at the luminal membrane. By contrast NAC-S-CH(3)Hg and Cys-S-CH(3)Hg (in the presence of DMPS) are not taken up avidly at the luminal membrane of proximal tubular cells, thus promoting the excretion of CH(3)Hg(+) into the urine.

Effects of co-administration of dietary sodium arsenate and 2,3-dimercaptopropane-1-sulfonic acid (DMPS) on the rat bladder epithelium.

Inorganic arsenic is a known human carcinogen, inducing tumors of the skin, urinary bladder and lung. It is metabolized to organic methylated arsenicals. 2,3-Dimercaptopropane-1-sulfonic acid (DMPS), a chelating agent, is capable of reducing pentavalent arsenicals to the trivalent state and binding to the trivalent species, and it has been used in the treatment of heavy metal poisoning in humans. Therefore, we investigated the ability of DMPS to inhibit the cytotoxicity and regenerative urothelial cell proliferation induced by arsenate administration in vivo. Female rats were treated for 4 weeks with 100 ppm As(V). DMPS (2800 ppm) co-administered in the diet significantly reduced the As(V)-induced cytotoxicity of superficial cells detected by scanning electron microscopy (SEM), and the incidence of simple hyperplasia observed by light microscopy and the bromodeoxyuridine (BrdU) labeling index. It also reduced the total concentration of arsenicals in the urine and the methylation of arsenic. There were no differences in oxidative stress as assessed by immunohistochemical staining for 8-hydroxy-2'-deoxyguanosine (8OHdG) of the bladder urothelium. No differences were detected in urine sediments between groups. These data suggest that DMPS has the ability to inhibit both arsenate-induced acute toxicity and regenerative proliferation of the rat bladder epithelium, most likely by decreasing exposure of the urothelium to trivalent arsenicals excreted in the urine. These data provide additional evidence that the effects of arsenate exposure in vivo do not appear to be related to oxidative effects on dG in DNA.

Influence of glutathione chemical effectors in the response of maize to arsenic exposure.

To support the key role of glutathione (GSH) in the mechanisms of tolerance and accumulation of arsenic in plants, this work examines the impact of several effectors of GSH synthesis or action in the response of maize (Zea mays L.) to arsenic. Maize was exposed in hydroponics to iso-toxic rates of 150 µM arsenate or 75 µM arsenite for 9 days and GSH effectors, flurazole (an herbicide safener), l-buthionine-sulfoximine (BSO, a known inhibitor of GSH biosynthesis), and dimercaptosuccinate (DMS) and dimercaptopropanesulfonate (DMPS) (two thiols able to displace GSH from arsenite-GSH complexes) were assayed. The main responses of plants to arsenic exposure consisted of a biomass reduction (fresh weight basis) of about 50%, an increase of non-protein thiol (NPTs) levels (especially in the GSH precursor γ-glutamylcysteine and the phytochelatins PC2 and PC3) in roots, with little effect in shoots, and an accumulation of between 600 and 1000 ppm of As (dry weight basis) in roots with very little translocation to shoots. Growth inhibition caused by arsenic was partially or completely reversed in plants co-treated with flurazole and arsenate or arsenite, respectively, highly exacerbated in plants co-treated with BSO, and not modified in plants co-treated with DMS or DMPS. These responses correlated well with an increase of both NPTs levels in roots and glutathione transferase activity in roots and shoots due to flurazole treatment, the decrease of NPTs levels in roots caused by BSO and the lack of effect on NPT levels caused by both DMS and DMPS. Regarding to arsenic accumulation in roots, it was not modified by flurazole, highly reduced by BSO, and increased between 2.5- and 4.0-fold by DMS and DMPS. Therefore, tolerance and accumulation of arsenic by maize could be manipulated pharmacologically by chemical effectors of GSH.

[Antioxidant properties of some sulfur-containing substances].

The antioxidant properties of sulfur-containing substances have been experimentally studied in vitro. Unithiol exhibits a wide spectrum us radicals. For this reason, unithiol can be considered, along with ascorbic acid, as a universal drug for the reduction of free radical reactions.

[Experimental therapeutic effects of hybrid liposomes on the Alzheimer's disease in vitro].

Accumulation of ß amyloid (Aß) peptides to nerve cells should be associated with the onset of Alzheimer's disease (AD). We prepared hybrid liposomes (HL) composed of 90 mol% phospholipids having various charged head groups (cationic L-α-dimyristoyltrimethyl ammonium propane (DMTAP), anionic L-α-dimyristoylphosphatidylserine (DMPS) or zwitterionic L-α-dimyristoylphosphatidylcholine (DMPC)) and 10 mol% polyoxyethylene(23) dodecyl ether (C(12)(EO)(23))), and investigated the inhibitory effects of HL on the accumulation of Aß(1-40) peptides into human neuroblastoma (SH-SY5Y) cells in vitro. It is noteworthy that remarkable inhibitory effects on the accumulation of Aß(1-40) peptides were observed for SH-SY5Y cells treated with anionic HL-DMPS, though the accumulation was not inhibited by cationic HL-DMTAP. On the other hand, the immediate fusion of HL-DMTAP into SH-SY5Y cells was confirmed using a confocal laser microscope. Interestingly, the specific interactions between anionic HL-DMPS and Aß(1-40) peptides were observed using the thioflavin T (ThT) assay. In addition, the cytotoxicity of Aß(1-42) peptides on the SH-SY5Y cells decreased after the treatment with HL-DMPS. These results suggest that anionic HL-DMPS could be used as a novel medicine for AD in the future.

[Antiviral activity of recombinant interferon-alpha-2b in combination with certain antioxidant].

In vitro activity of interferon-alpha-2b in combination with various antioxidants against the influenza virus and Herpes simplex was studied. The standard strains and a clinical strain of Herpes simplex isolated from a patient with resistance to acyclovir were used. The in vitro studie showed that antioxidants, such as alpho-tocoferol acetate (vitamin E), Unithiol and ascorbic acid had a significant antiinfluenzae and antiherpetic action on the influenza virus A/H5N1 and Herpes simplex variants. They protected up to 100% of the cell monolayer from the virus cytopathic effect. The taurin solutions had no antiviral activity irrespective of the infection dose. Combinations of interferon-alpha-2b with alpha-tocopherol acetate (vitamin E), Unithiol or ascorbic acid showed a significant synergistic effect: the antiviral activity of interferon increased several times. The antiinfluenza activity of interferon-a-2b in the presence of various concentrations of taurin did not change.