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An approach was made to enhance the halophilic lipase secretion by a newly isolated moderate halophilic Marinobacter litoralis SW-45, through the statistical optimization of Plackett-Burman (PB) experimental design and the Face Centered Central Composite Design (FCCCD). Initially, PB statistical design was used to screen the medium components and process parameters, while the One-factor-at-a-time technique was availed to find the optimum level of significant parameters. It was found that MgSO 4  · 7H 2 O, NaCl, agitation speed, FeSO 4  · 7H 2 O, yeast extract and KCl positively influence the halophilic lipase production, whereas temperature, carbon source (maltose), inducer (olive oil), inoculum size, and casein-peptone had a negative effect on enzyme production. The optimum level of halophilic lipase production was obtained at 3.0 g L -1 maltose, 1% (v/v) olive oil, 30 °C growth temperature and 4% inoculum volume (v/v). Further optimization by FCCCD was revealed 1.7 folds improvement in the halophilic lipase production from 0.603 U ml -1 to 1.0307 U ml -1 . Functional and biochemical characterizations displayed that the lipase was significantly active and stable in the pH ranges of 7.0-9.5, temperature (30-50 °C), and NaCl concentration (0-21%). The lipase was maximally active at pH 8.0, 12% (w/v) NaCl, and 50 °C temperature. Besides, M. litoralis SW-45 lipase was found to possess the promising industrial potential to be utilized as a biocatalyst for the esterification., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel β-agarase, AgaJ5, was identified from an agar-degrading marine bacterium, Gayadomonas joobiniege G7. It belongs to the glycoside hydrolase family 86 and is composed of 805 amino acids with a 30-amino-acid signal peptide. Zymogram analysis showed that purified AgaJ5 has agarase activity. The optimum temperature and pH for AgaJ5 activity were determined to be 30°C and 4.5, respectively. AgaJ5 was an acidic β-agarase that had strong activity at a narrow pH range of 4.5-5.5, and was a cold-adapted enzyme, retaining 40% of enzymatic activity at 10°C. AgaJ5 required monovalent ions such as Na + and K + for its maximum activity, but its activity was severely inhibited by several metal ions. The K m and V max of AgaJ5 for agarose were 8.9 mg/ml and 188.6 U/mg, respectively. Notably, thin-layer chromatography, mass spectrometry, and agarose-liquefication analyses revealed that AgaJ5 was an endo-type β-agarase producing neoagarohexaose as the final main product of agarose hydrolysis. Therefore, these results suggest that AgaJ5 from G. joobiniege G7 is a novel endo-type neoagarohexaose-producing β-agarase having specific biochemical features that may be useful for industrial applications.

The absence of effective therapeutics against Alzheimer's disease (AD) is a result of the limited understanding of its multifaceted aetiology. Because of the lack of chemical tools to identify pathological factors, investigations into AD pathogenesis have also been insubstantial. Here we report chemical regulators that demonstrate distinct specificity towards targets linked to AD pathology, including metals, amyloid-β (Aβ), metal-Aβ, reactive oxygen species, and free organic radicals. We obtained these chemical regulators through a rational structure-mechanism-based design strategy. We performed structural variations of small molecules for fine-tuning their electronic properties, such as ionization potentials and mechanistic pathways for reactivity towards different targets. We established in vitro and/or in vivo efficacies of the regulators for modulating their targets' reactivities, ameliorating toxicity, reducing amyloid pathology, and improving cognitive deficits. Our chemical tools show promise for deciphering AD pathogenesis and discovering effective drugs.

Dissolved organic matter (DOM) exerts direct and indirect influences on aquatic organisms. In order to better understand how DOM causes these effects, potentiometric titration was carried out for a wide range of autochthonous and terrigenous freshwater DOM isolates. The isolates were previously characterized by absorbance and fluorescence spectroscopy. Proton binding constants (pKa) were grouped into three classes: acidic (pKa≤5), intermediate (58.5). Generally, the proton site densities (LT) showed maximum peaks at the acidic and basic ends around pKa values of 3.5 and 10, respectively. More variably positioned peaks occurred in the intermediate pKa range. The acid-base titrations revealed the dominance of carboxylic and phenolic ligands with a trend for more autochthonous sources to have higher total LT. A summary parameter, referred to as the Proton Binding Index (PBI), was introduced to summarize chemical reactivity of DOMs based on the data of pKa and LT. Then, the already published spectroscopic data were explored and the specific absorbance coefficient at 340nm (i.e. SAC340), an index of DOM aromaticity, was found to exhibit a strong correlation with PBI. Thus, the tendencies observed in the literature that darker organic matter is more protective against metal toxicity and more effective in altering physiological processes in aquatic organisms can now be rationalized on a basis of chemical reactivity to protons., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Isoflavone metal chelates are of interest as isoflavones act as oestrogen mimics. Metal interactions may enhance isoflavones biological properties so understanding isoflavone metal chelation is important for the commercial application of isoflavones. This work aimed to determine if isoflavones, daidzein (4',7-dihydroxyisoflavone) and genistein (4',5,7-trihydroxyisoflavone) could chelate with metals as isoflavone chelates. Biochanin A (4'-methoxy-5,7-dihydroxyisoflavone) was also examined for it's ability to chelate with Cu(II) and Fe(III). This study found daidzein does not chelate with Cu(II) and Fe(III) but genistein and biochanin A chelate with a 1:2 M/L stoichiometry. The copper and iron chelates were synthesised and characterised by elemental analysis, FTIR, thermogravimetric analysis (TGA) and electrospray ionisation mass spectrometry (ESI-MS). These studies indicated a 1:2 M/L stoichiometry and suggested the isoflavones bind with the metals at the 4-keto and the 5-OH site. 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition assays showed that copper isoflavone chelates have higher antioxidant activity than free isoflavones while the iron isoflavone chelates showed pro-oxidant activity compared to the free isoflavone. Synergistic DPPH studies with 0.02 mM ascorbic acid revealed copper chelates exhibit reduced antioxidant activity versus free isoflavones whereas the iron chelates showed lower pro-oxidant activity except at 1.0 mM., (Copyright 2010 Elsevier Inc. All rights reserved.)

(Neuro-)toxicity of metal and metal compounds is frequently highlighted. While specific metals or metal compounds are essential for cellular function, other metals are toxic and/or carcinogens. Metals can trigger accidental cell death in the form of necrosis, or activate programmed cell death in the form of apoptosis. The aim of anti-cancer therapy is induction of apoptosis in tumor cells. Therefore, there is an interesting twist in the toxicity of metals and metal compounds (e.g., arsenic trioxide, cisplatin); since they have a higher specificity to induce apoptosis in cancer cells (possibly due to the high turnover in these cells) they are used to cure some forms of cancer. A body of evidence suggests that second messengers, such as modulations in the intracellular calcium concentration, could be involved in metals induced toxicity as well as in the beneficial effects shown by anti-cancer drugs. Here we review the influence on calcium homeostasis induced by some metallic compounds: cisplatin, arsenic trioxide and trimethyltin chloride.

Background and Purpose: DP-b99 is a chelator of zinc and calcium ions that acts selectively within cell membranes and has neuroprotective properties in animal models of stroke. We present the results of a multicenter, double-blind, placebo-controlled, randomized trial to assess the safety and potential protective effects of DP-b99 in acute ischemic stroke., Methods: One hundred and fifty stroke patients with signs of cortical involvement and a National Institutes of Health Stroke Scale (NIHSS) score of 7 to 20 received a 4-day course of intravenous 1 mg/kg per day DP-b99 or placebo within 1 to 9 hours of stroke onset. Treatment with recombinant tissue plasminogen activator was not allowed., Results: No major differences in mortality rate, causes of death, adverse events, safety laboratory tests, and ECG parameters were found between the 2 groups. The baseline NIHSS score of the 72 DP-b99- and 75 placebo-treated patients in the intent-to-treat cohort was (mean+/-SD) 12.2+/-4.0 and 12.6+/-3.3, respectively; the time to needle (mean+/-SD) was 6:36+/-1:47 and 6:28+/-1:33 hours, respectively; and the age (mean+/-SD) was 73.3+/-9.9 and 72.0+/-9.6 years, respectively. The 90-day median change from baseline (the primary end point) was -6.0 and -5.0 NIHSS points in the DP-b99 and placebo groups, respectively (nonsignificant). At 90 days, there was a significantly better outcome in the DP-b99 group compared with the placebo group (modified Rankin scale score of 0, 1, or same as prestroke): 30.6% and 16.0%, respectively (P=0.05). The recovery rate was unaffected by the time to needle. Further analyses indicated that the 90-day median change from baseline in patients with an entry NIHSS score of 10 to 16 was 8.0 and 5.0 points in the DP-b99 and placebo groups, respectively (P=0.03)., Conclusions: In this small-scale study, the primary end point of change in NIHSS score from baseline to 90 days was not met. However, secondary end points demonstrated a significantly improved 90-day recovery rate with treatment with DP-b99 when compared with placebo. In addition, in patients with baseline NIHSS scores of 10 to 16, a significant post hoc change in NIHSS score from baseline to day 90 was observed. No major safety problems were identified. These findings need to be confirmed with a larger prospective study of strokes involving the cortex.

Neurotoxic metal-induced oxidative damage to nervous tissue has been implicated in several progressive neurodegenerative disorders including Alzheimer's disease. In this study, using human brain cells in primary culture, the quenching of metal sulfate-induced reactive oxygen species (ROS) and ROS-sensitive gene expression was studied using the antioxidants ascorbate, folic acid, phenyl butyl nitrone and the chelators desferrioxamine and Feralex-G. Antioxidants ascorbate, folic acid, phenyl butyl nitrone, desferrioxamine or Feralex-G were found to quench ROS and cPLA2 and COX-2 gene induction to various degrees, and a synergism was observed when certain combinations of them were used. These findings support the idea that specific antioxidants and metal ion chelators when used together can effectively and synergistically quench ROS-mediated induction of pathogenic gene expression.

One of the hypotheses for the development of familial amyotrophic lateral sclerosis (ALS) is that mutations in the superoxide dismutase 1 enzyme lead to aberrant properties of the copper within the active site of the enzyme which then causes increased oxidative damage. The lipophilic metal chelators DP-109 and DP-460 which chelate calcium, copper, and zinc were tested in the G93A-transgenic ALS mouse model. Both compounds significantly extended survival, DP-109 (5 mg/kg/day) by 10%, DP-460 (10 mg/kg/day) by 9%. While the effect on survival was relatively small, chelator treatment also improved motor performance, dramatically reduced cell loss in the lumbar spinal cord and decreased reactive astrocytosis and microgliosis. Markers of oxidative damage, tumor necrosis factor (TNF)-alpha and alpha-synuclein were reduced in the lumbar spinal cord of G93A mice treated with DP-109 or DP-460 as compared with vehicle-treated animals. Furthermore, the treatment induced protein expression of the transcription factor hypoxia inducible factor-1alpha and mRNA levels of vascular endothelial growth factor as a corresponding target gene. In line with previous studies using metal chelators in the G93A animal model, our results suggest that these compounds have neuroprotective capacities in ALS.

Food constituents are the major source of various phytochemicals and micronutrients. The importance of these dietary constituents has been stressed in recent years due to their antioxidant and anticarcinogenic potential. Spices used in Indian foods such as cloves (Syzygium aromaticum), licorice (Glycyrrhiza glabra), mace (aril of Myristica fragans), and greater cardamom (Amomum subulatum) were tested for their antioxidant properties in vitro. The metal chelating activity, bleomycin dependent DNA oxidation, diphenyl-p-picryl hydrazyl (DPPH) radical scavenging activity and the ferric reducing /antioxidant power (FRAP) were measured in rat liver homogenate in presence of spices. Metal chelating activity was significantly high with all the spice extracts except mace. The spices due to higher reducing potential (in presence of bleomycin-FeCl_{3}) showed increased DNA oxidation. Cloves showed the highest DPPH radical scavenging activity, followed by licorice, mace and cardamom. FRAP values for cloves were also the highest, while other spices showed comparatively lesser FRAP values. The results show that the spices tested are strong antioxidants and may have beneficial effects on human health.

Iron is critical for cell growth and proliferation. Iron chelators are being explored for a number of clinical applications, including the treatment of neurodegenerative disorders, heart disease, and cancer. To uncover mechanisms of action of tachpyridine, a chelator currently undergoing preclinical evaluation as an anticancer agent, cell-cycle analysis was performed. Tachpyridine arrested cells at G2, a radiosensitive phase of the cell cycle, and enhanced the sensitivity of cancer cells but not nontransformed cells to ionizing radiation. G2 arrest was p53 independent and was accompanied by activation of the checkpoint kinases CHK1 and CHK2. G2 arrest was blocked by UCN-01, a CHK1 inhibitor, but proceeded in CHK2 knock-out cells, indicating a critical role for CHK1 in G2 arrest. Tachpyridine-induced cell-cycle arrest was abrogated in cells treated with caffeine, an inhibitor of the ataxia-telangiectasia mutated/ataxia-telangiectasia-mutated and Rad3-related (ATM/ATR) kinases. Further, G2 arrest proceeded in ATM-deficient cells but was blocked in ATR-deficient cells, implicating ATR as the proximal kinase in tachpyridine-mediated G2 arrest. Collectively, our results suggest that iron chelators may function as antitumor and radioenhancing agents and uncover a previously unexplored activity of iron chelators in activation of ATR and checkpoint kinases.

Melatonin is a well-known hydroxyl radical (*OH) scavenger that protects DNA and lipids from free radical attack. In this paper, we studied the ability of melatonin to prevent oxidative damage to bovine serum albumin (BSA) induced by two different paradigms: the metal-catalyzed oxidation (MCO) induced by Cu(2+)/H(2)O(2) and the alkoxyl and alkylperoxyl radicals formed by the azo initiator 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH, 40 mM). The protective effects of melatonin were compared with 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox), glutathione (GSH), ascorbate, 3,4',5-trihydroxy-trans-stilbene (resveratrol, 0.1 microM-4 mM) and mannitol (50 microM-100 mM). Melatonin efficiently prevented protein modification induced by both models, as assayed by polyacrylamide gel electrophoresis and carbonyl content. Both trolox and ascorbate had an obvious pro-oxidant effect in the Cu(2+)/H(2)O(2) model, whereas both prevented BSA damage induced by AAPH. In the MCO model, the efficacy of GSH in terms of protein protection was higher than melatonin at relatively high concentrations (250 microM-4 mM); however, at lower concentrations (50-250 microM), the efficacy of melatonin was superior to GSH. D-Mannitol (50 microM-100 mM) and resveratrol did not protect BSA from the site-specific damage induced by Cu(2+)/H(2)O(2). On the other hand, the relative protective efficiency in the AAPH model was melatonin approximately trolox>GSH>ascorbate.

Background: The transition metal-catalyzed reaction is a major source of oxygen free radicals, which play an important role in vascular dysfunction leading to ischemia in diabetic tissues. The inhibition of polyol pathway hyperactivity has been reported to ameliorate neurovascular abnormalities in diabetic rats and has been proposed to improve the oxygen free radical scavenging capacity. The present study was conducted to compare the effect of a transition metal chelating agent, trientine (TRI), on diabetic neuropathy with that of an aldose reductase inhibitor, NZ-314 (NZ)., Methods: Diabetic rats were divided into three groups: (1). untreated, (2). TRI-treated, and (3). NZ-treated. TRI (20 mg/kg) or NZ (100 mg/kg) was administered by gavage or chow containing NZ, respectively, for 8 weeks. Motor nerve conduction velocity (MNCV), coefficient of variation of the R - R interval on electrocardiogram (CVr-r), sciatic nerve blood flow (SNBF), platelet aggregation activities, and serum concentrations of malondialdehyde were measured., Results: Untreated diabetic rats showed delayed MNCV, decreased CV(R-R), and reduced SNBF compared to normal rats. TRI or NZ completely prevented these deficits. Platelet hyperaggregation activities in diabetic rats were prevented by NZ, but not by TRI. Increased concentrations of malondialdehyde in diabetic rats were partially but significantly ameliorated by either TRI or NZ., Conclusions: These observations suggest that increased free radical formation through the transition metal-catalyzed reaction plays an important role in the development of diabetic neuropathy and that the preventive effect of an aldose reductase inhibitor on diabetic neuropathy may also be mediated by decreasing oxygen free radicals., (Copyright 2002 John Wiley & Sons, Ltd.)

Aggregated and oligomeric amyloid beta-protein (Abeta) is known to exhibit neurotoxicity. However, the action of Abeta monomers on neurons is not fully understood. We have studied aggregation state-dependent actions of Abeta and found an oligomer-specific effect of Abeta on lipid metabolism in neurons (Michikawa et al., 2001). Here, we show a novel function of monomeric Abeta1-40, which is the major species found in physiological fluid, as a natural antioxidant molecule that prevents neuronal death caused by transition metal-induced oxidative damage. Monomeric Abeta1-40, which is demonstrated by SDS-PAGE after treatment with glutaraldehyde, protects neurons cultured in a medium containing 1.5 microm Fe(II) without antioxidant molecules. Metal ion chelators such as EDTA, CDTA (trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid), and DTPA (diethylenetriamine-N,N,N',N",N"-penta-acetic acid, an iron-binding protein, transferrin, and antioxidant scavengers such as catalase, glutathione, and vitamin E also inhibit neuronal death under the same conditions. Monomeric Abeta1-40 inhibits neuronal death caused by Cu(II), Fe(II), and Fe(III) but does not protect neurons against H2O2-induced damage. Monomeric Abeta1-40 inhibits the reduction of Fe(III) induced by vitamin C and the generation of superoxides and prevents lipid peroxidation induced by Fe(II). Abeta1-42 remaining as a monomer also exhibits antioxidant and neuroprotective effects. In contrast, oligomeric and aggregated Abeta1-40 and Abeta1-42 lose their neuroprotective activity. These results indicate that monomeric Abeta protects neurons by quenching metal-inducible oxygen radical generation and thereby inhibiting neurotoxicity. Because aggregated Abeta is known to be an oxygen radical generator, our results provide a novel concept that the aggregation-dependent biological effects of Abeta are dualistic, being either an oxygen radical generator or its inhibitor.

Metallothionein (MT) is a small-molecular weight, cysteine-rich protein that binds metals. The protective role of MT in Cd toxicity is well established but its ability to protect against toxicity of other metals remains unclear. In this study, wild-type and MT-I and -II null mice (MT-null mice) were used to determine whether MT is protective against the lethality of not only Cd but also Zn, Cu, Fe, Pb, Hg and As. Following daily subcutaneous administration of an increasing dose of each metal, starting with a low, non-toxic dose, we compared the cumulative median lethal dose (LD(50)) of each metal between wild-type and MT-null mice. The LD(50) of Cd for wild-type mice was 6.9-fold higher than for MT-null mice. The LD(50) of Zn was 2.4-fold higher for wild-type mice than for MT-null mice, and 1.4-fold higher for Cu and As. The LD(50) of Hg was 1.3-fold higher for wild-type mice than for MT-null mice, but this was not statistically significant. No difference in LD(50) values was observed between wild-type and MT-null mice following Pb and Fe administration. These results suggest that MT is an important protein in the cellular defense against Cd toxicity and lethality, but it provides much less protection against the lethality of the other metals.

The mechanism of DNA damage induced by metabolites of nitrobenzene was investigated in relation to the carcinogenicity and reproductive toxicity of nitrobenzene. Nitrosobenzene, a nitrobenzene metabolite, induced NADH plus Cu(II)-mediated DNA cleavage frequently at thymine and cytosine residues. Catalase and bathocuproine inhibited the DNA damage, suggesting the involvement of H2O2 and Cu(I). Typical free hydroxyl radical scavengers showed no inhibitory effects on DNA damage. Nitrosobenzene caused the formation of 8-oxo-7, 8-dihydro-2'-deoxyguanosine in calf thymus DNA in the presence of NADH and Cu(II). ESR spectroscopic study has confirmed that nitrosobenzene is reduced by NADH to the phenylhydronitroxide radical even in the absence of Cu(II). These results suggest that nitrosobenzene can be reduced non-enzymatically by NADH, and the redox cycle reaction resulted in oxidative DNA damage due to the copper-oxygen complex, derived from the reaction of Cu(I) with H2O2., (Copyright 1999 Academic Press.)

We investigated the effect of diphenylthiocarbazone (dithizone) and its structurally related compounds on the differentiation and apoptosis of two human myeloid leukemia cell lines. Dithizone caused a time- and concentration-dependent induction of differentiation in both the promyelocytic leukemia cell line HL-60 cells and the myeloblastic leukemia cell line ML-1 cells, as measured by nitroblue tetrazolium (NBT) reducing activity. Morphological changes and esterase activities confirmed that this differentiation took place. The induction of differentiation required the addition of dithizone to the culture medium for at least 12 h. The differentiation inducing activity was inhibited by the preincubation of dithizone with various metal ions such as Pb2+, Zn2+, Cu2+ and Mn2+ ions, but not with Fe3+ and Mg2+ ions. In addition, the DNA extracted from dithizone-treated HL-60 cells showed a typical ladder pattern characteristic of apoptosis in agarose gel electrophoresis. A quantitative analysis of DNA fragmentation revealed that this apoptosis was concentration- and time-dependent in both the HL-60 and ML-1 cells. Dithizone-induced apoptosis was also inhibited by preincubation with Mn2+ ions, but not with Mg2+ ions. These results indicate that dithizone induces both differentiation and apoptosis in HL-60 and ML-1 cells through a unique mechanism including metal chelation.

Five heavy metal antagonists were compared for their specificity of chelating action against copper (CuCl, CuCl2) and iron (FeCl2, FeCl3). ESR spectroscopy showed that both copper and iron significantly enhanced the radical intensity of ascorbate and sodium 5,6-benzylidene-L-ascorbate (SBA). Equimolar concentrations of dimercaprol efficiently chelated all these metals, thus significantly reducing their stimulation effects. On the other hand, the chelating action of penicillamine, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid was limited to CuCl and CuCl2 whereas deferoxamine mesylate (DFO) was a specific iron chelator. The cytotoxic activity of sodium ascorbate was augmented by DFO, but diminished by FeCl3. The simultaneous addition of DFO and FeCl3 counteracted each other, thus neutralizing their individual effects. The cytotoxic activity of both sodium ascorbate and SBA was significantly enhanced by CuCl2 and this stimulation effect of CuCl2 was effectively chelated by DTPA. The present study demonstrates the specificity of the chelating action of these five antagonists, suggesting the possible application of these different types of antagonists for the prevention of the pathogenic diseases catalyzed by the corresponding metals.

Cd2+ provokes an immediate production of inositol trisphosphate and the release of Ca2+ from internal stores in human fibroblasts and some other mammalian cells. Ni2+, Co2+, Fe2+, and Mn2+ evoke the release of stored Ca2+, but are less potent than Cd2+ (apparent K0.5 = 40 nM). Zn2+ and Cu2+ competitively inhibit Ca2+ release evoked by Cd2+ without affecting Ca2+ release by hormones such as bradykinin. Zn2+ has the same apparent Ki value (80-90 nM) towards the five agonist metals, which suggests that the metals interact with the same site. Many other divalent cations neither released stored Ca2+ nor affected Cd(2+)-evoked Ca2+ release. The agonist metals appear to activate phospholipase C via a G protein rather than a tyrosine kinase. The production of reactive oxygen species is probably not involved in Ca2+ release by the metals. Cd2+ and other stimuli that raise cytosolic-free Ca2+ induce cyclic (AMP) production, apparently by activating a calmodulin-dependent adenylyl cyclase. We suggest that an orphan receptor mediates the hormonelike responses to Cd2+ and the other agonist metals. The receptor is referred to as an orphan because its physiological stimulus is unknown. Growth of the fibroblasts in high Zn2+ desensitizes them to the five agonist metals without affecting Ca2+ release by bradykinin or histamine. A several hour incubation in culture medium with normal Zn2+ fully restores responsiveness to the five active metals. Growth in high Zn2+ appears to repress the synthesis of the putative orphan receptor because inhibitors of RNA or protein synthesis, or asparagine-linked glycosylation, prevented the restoration of metal responsiveness.(ABSTRACT TRUNCATED AT 250 WORDS)

The molecular mechanisms of selenium regulation of biochemical functions in animal and human tissues are presented in review. It is shown, that in spite of high toxicity selenium is an essential nutrient for people and animals. Taking into account deficit of this microelement in fodder it is necessary to use the selenium compounds in rations of domestic animals and poultry. The study of properties and characteristics of selenoproteins is important in discovering selenium role in regulation of cellular growth processes, the protective effect of this element in prevention of toxic action of heavy metals, xenobiotics and bacterial toxins on organism and anticarcinogenic effect of selenium.

It is well established that certain metals are toxic to embryonic and fetal tissues and can induce teratogenicity in mammals. The main objective of this paper has been to summarize the toxic effects that excesses of certain metals may cause on mammalian development. The reviewed elements have been divided into four groups: (a) metals of greatest toxicological significance (arsenic, cadmium, lead, mercury, and uranium) that are wide-spread in the human environment, (b) essential trace metals (chromium, cobalt, manganese, selenium, and zinc), (c) other metals with evident biological interest (nickel and vanadium), and (d) metals of pharmacological interest (aluminum, gallium, and lithium). A summary of the therapeutic use of chelating agents in the prevention of metal-induced developmental toxicity has also been included. meso-2,3-Dimercaptosuccinic acid (DMSA) and sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) have been reported to be effective in alleviating arsenic- and mercury-induced teratogenesis, whereas sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) would protect against vanadium- and uranium-induced developmental toxicity.

The potential of chlorophyllin in reducing clastogenicity was studied against two concentrations of each of three potent metallic clastogens (cesium chloride, mercuric chloride and cobalt chloride) in bone marrow cells of mice in vivo. The respective salts and chlorophyllin were administered orally to mice by gavaging in different combinations. Simultaneous administration of chlorophyllin with both concentrations of each salt reduced the clastogenic effects in the order Cs greater than Hg greater than Co. Chlorophyllin could not decrease the clastogenic effects when administered 2 h before the salts.

The hydrolysis of olive oil catalyzed by Candida rugosa lipase solubilized in "H2O/AOT/isooctane" reverse micellar solution has been studied. The optimal conditions observed for lipase in reverse micelles were t = 25 degrees C, pH = 7.9, and R = [H2O]/[AOT] = 10. Lipase in reverse micelles is found to be quite stable. For example, after being incubated at 33 degrees C for 12 hours in AOT/isooctane with R = 5.4, the residual activity of lipase remains as high as 89%. No inhibition was observed even though the substrate concentration was increased up to 50% (v/v), and it was inhibited slightly when 40 mM Cu2+, Co2+ or Mn2+ ions were in the water pools.

A literature survey was made of the interactions--in the organism--between some food contaminating elements (mercury, tin, nickel, selenium, fluorine, aluminium) and iron, zinc and copper. The harmful elements may disturb the mineral metabolism already at the stage of intestinal absorption. Moreover, they bring about changes in microelement distribution in the tissues and cells. On account of their approximately similar chemical structure, they compete for the sites of binding to some proteins, including enzymic ones. In this respect a special role is played by ++metallothionein, a protein with the ability of regulating free metal contents in the tissues and thus possibly displaying some detoxifying properties. Many mechanisms and relationships determining the interactions between the surveyed food contaminants and iron, zinc and copper remain, however, not elucidated.

The purpose of the present study was to obtain new data on the effect of age, route, dose and time of metal and chelating agent administration on the efficiency of chelation therapy. The experiments were performed on 1-2 and 6-week-old rats which received radioisotopes of metals--203Pb, 115 mCd, 203Hg and 141Ce intraperitoneally or orally. Chelating agents calcium ethylenediaminetetraacetate (CaEDTA), calcium and zinc diethylenetriaminepentaacetate (CaDTPA, ZnDTPA), 2,3-dimercapto-propane-sulfonate-1 (DMPS), dimercaptosuccinic acid (DMSA) and sodium N-(4-methoxybenzyl)-D-glucamine dithiocarbamate monohydrate (MeOBDCG) were administered twice by intraperitoneal or oral administration as early (immediately and 24 hr after metals) or delayed treatment (24 and 48 or 48 and 72 hr after metals). The animals were killed six days after metal administration and the retention was determined in the whole body, carcass and gut. After intraperitoneal administration of metals and chelating agents chelation therapy had much lower efficacy in younger than older animals. After ingestion of metals oral chelation therapy was more effective in younger than older animals. In suckling rats the treatment effectively reduced metal retention and this was mostly due to decrease in gut retention. This treatment in sucklings was also very effective in condition of late administration. In older rats early oral DMPS treatment after 203Hg ingestion is contraindicated since it increases significantly mercury retention while DMSA and ZnDTPA treatments reduced mercury retention. Delayed oral treatment with ZnDTPA and DMSA caused increased cadmium retention in older rats and decreased retention in sucklings. Opposite to results with CaDTPA, MeOBDCG was effective in reducing cadmium retention also when given as delayed treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug resistance of 271 strains of coagulase negative staphylococci isolated mainly from the upper respiratory tract and skin of healthy animals (cows, sheep, swine, hen, monkey, mink, sable and fox) was studied. Benzylpenicillin, streptomycin, tetracycline, chloramphenicol, erythromycin, oleandomycin, neomycin, monomycin, kanamycin and novobiocin and heavy metal salts, such as mercurous chloride and cadmium sulfate were used in the study. Unlike coagulase positive staphylococci isolated from the same sources, the coagulase negative strains were more frequently resistant to novobiocin (a specific feature of a number of the strains) and tetracycline and much less frequently resistant to benzylpenicillin and streptomycin. The differences in the drug resistance of the coagulase negative staphylococci were more often associated with the species taxonomic position than with the source of their isolation. The highest number of the strains resistant to all the antibiotics tested except novobiocin belonged to Staph. epidermidis and the lowest number of the strains resistant to all the antibiotics tested except novobiocin belonged to Staph. xylosus, Staph. sciuri, Staph. simulans and Staph. hyicus.

From a consideration of the donor preferences of toxic metals and the acceptor preferences of commonly used therapeutic chelating agents it is often possible to get a good estimate of the kinds of chelating agent which may be effective antagonists. The relative importance of extracellular vs. intracellular metal, however, introduces an important factor which can severely limit the utility of a given chelating agent with a toxic metal with which it forms very stable complexes. In general an effective antagonists of a specific toxic metal will be a chelating agent which can gain access to the metal in vivo and which forms a very stable complex, of modest toxicity with that metal ion which is rapidly excreted without damage to the kidney or liver. Such effective antagonists are not known for all metals.

Occurrence of the markers of penicillin and erythromycin resistance in the clinical strains of Staph. aureus, as well as their connection with the determinants of resistance to the heavy metal salts and sodium arsenate was studied. 79 per cent of Staph. aureus were resistant to penicillin and 47 per cent to erythromycin. All erythromycin resistant strains were also resistant to penicillin. More than a half of the strains of Staph. aureus of the phage groups I, III and the mixed phage group had a set of markers: pen, asa, cad, mer, ego. The rate of elimination of the above markers with ethidium bromide was high. The presence of the penicillinase plasmid determining a rather low level of resistance to erythromycin (20--50 gamma/ml) was characteristic of the strains belonging to the phage group I. The presence of the plasmid determining a high level of resistance to that drug (500--1000 gamma/ml) was characteristic of the phage group III and the mixed phage group. The erythromycin sensitive strains of Staph. aureus were almost always sensitive to mercuric ions.

Therapy of acute heavy metal poisoning is currently limited to a group of moderately toxic drugs containing sulfhydryl groups. N-Acetylcysteine (NAC) was used in these studies to determine if this sulfhydryl containing amino acid would reduce the overall mortality of a group of heavy metal compounds. D-Penicillamine and dimercaprol (BAL) were also used for comparison. Groups of at least 100 mice (28 g) were injected subcutaneously with 2-190 mg/kg of copper, arsenic, thallium or cadmium for LD50 determinations. Other groups were injected 30-60 min later with NAC (200 mg/kg), d-penicillamine (50 mg/kg), or BAL (10 mg/kg), and mortality was monitored for 2 weeks. The LD50 for each treatment group was determined by regression analysis of log-probit transformed data. In arsenite treatment group the survival time was lengthened in NAC-treated animals although the LD50 was not significantly changed. BAL was only slightly more effective than NAC. The mortality in animals given copper and treated with NAC was almost eliminated, except at the highest doses. BAL provided the greatest protection, whereas d-penicillamine produced the least. The LD50 of copper was significantly changed from 60.5 mg/kg in control groups to 139 mg/kg in NAC-treated groups, and to 150 mg/kg and 91 mg/kg in BAL and d-penicillamine-treated groups. NAC and BAL were totally ineffective in the treatment of thallium and cadmium poisoning.

Ferritin binds a large quantity of Be2+ (Price D.J. and Joshi, J.G. J. Biol. Chem. 258 (1983) 10873) as well as other divalent metal ions. Therefore the ability of this protein to protect enzymes against or reverse the inhibition by metal ions was studied. Evidence presented here shows that the inhibition by Be2+ of the enzymes Na+K+ATPase, alkaline phosphatase and phosphoglucomutase is reversed by ferritin. Be2+ can be transferred reversibly between phosphoglucomutase and ferritin depending upon the relative concentrations of the 2 proteins. Ferritin also reactivated phosphoglucomutase inhibited by Zn2+, Cu2+, or Cd2+. Incubation of ferritin containing Be2+ with 4-10 fold molar excess of phosphoglucomutase (with respect to Be2+) removed 90% of the Be2+ from ferritin. The rates of inactivation of phosphoglucomutase by Be2+ donated by apoferritin or ferritin were identical. Based upon these observations it is suggested that Be2+ bound to the protein shell and to the iron core are in equilibrium with each other with the equilibrium favoring ferritin-Be2+ complex.