Mechanistic insights into the interaction between energetic oxygen ions and nanosized ZnFe2O4: XAS-XMCD investigations

Irradiation of nanosized zinc ferrite with swift heavy ions leads to cation redistribution and changes in magnetic interactions.

HRTEM and FTIR investigation of nanosized zinc ferrite irradiated with 100 MeV oxygen ions

Present work aims to investigate effect of 100 MeV oxygen ion irradiation on the vibrational modes of zinc ferrite nanoparticles. Nanosize zinc ferrite systems of different crystallite size ranging from 12-62 nm were irradiated at the fluence of 1×10(13) and 5×10(13) ions/cm(2). High resolution transmission electron micrograph study indicates the structural disorder induced by ion irradiation. Bands corresponding to various vibrational modes in Fourier transform infrared spectra exhibit changes and are affected by the crystallite size/microstructure of pristine samples. The irradiation induced changes are dominated for sample ZF1000.

Estimation of phytochemicals and antioxidant activity of underutilized fruits of Andaman Islands (India)

The present study aimed to determine the antioxidant activity and phytochemical contents in 10 underutilized fruits of Andaman Islands (India) namely Malpighia glabra L., Mangifera andamanica L., Morinda citrifolia L., Syzygium aqueum (Burm.f) Alst., Annona squamosa L., Averrhoa carambola L., Averrhoa bilimbi L., Dillenia indica L., Annona muricata L. and Ficus racemosa L. The antioxidant activity varied from 74.27% to 98.77%, and the methanol extract of M. glabra showed the highest antioxidant activity (98.77%; inhibitory concentration, IC(50) = 262.46 μg/ml). Methanol was found to be a better solvent than acetone and aqueous for estimating the antioxidant activity. M. glabra was found to be rich in phytochemicals viz. polyphenol (355.74 mg/100 g), anthocyanin (91.31 mg/100 g), carotenoids (109.16 mg/100 g), tannin (24.39 mg/100 g) and ascorbic acid (394.23 mg/100 g). Carbohydrate content was estimated to be highest in M. glabra (548 mg/100 g). Phenols, tannins, anthocyanins and carotenoids contents showed positive correlation (r² = 0.846, r² = 0.864, r² = 0.915 and r² = 0.806, respectively) with antioxidant activity. The information generated in present study will be useful for bioprospecting of underutilized fruits of Andaman Islands.

Rapid structural mapping of ternary metallic alloy systems using the combinatorial approach and cluster analysis

We are developing a procedure for the quick identification of structural phases in thin film composition spread experiments which map large fractions of compositional phase diagrams of ternary metallic alloy systems. An in-house scanning x-ray microdiffractometer is used to obtain x-ray spectra from 273 different compositions on a single composition spread library. A cluster analysis software is then used to sort the spectra into groups in order to rapidly discover the distribution of phases on the ternary diagram. The most representative pattern of each group is then compared to a database of known structures to identify known phases. Using this method, the arduous analysis and classification of hundreds of spectra is reduced to a much shorter analysis of only a few spectra.

Dynamic instability at liquid/vapor interface far from equilibrium

Attempt has been made to elucidate the mechanism of electric potential oscillations at oil-aqueous solution interface involving adsorption at oil-vapor interface on a semi-theoretical basis. The mechanism stipulates adsorption of ammonia, amines and pheromones at the liquid-vapor interface followed by transfer of ions through membrane-aqueous solution interface and subsequent interaction of ammonium (amine) ions and carbocations from pheromones with diffusing halide ions from the bulk. Relationship of the above mechanism with sensing mechanism of smell by olfactory nerves has also been pointed out.

Role of liquid membrane phenomenon in the biological actions of thioridazine

Role of surface activity in the mechanism of action of thioridazine (THR) has been studied. THR has been shown to generate liquid membrane it self and also in association with the relevant membrane lipids, sphingomyelin and cholesterol in series with a supporting membrane. Transport of relevant biogenic amines e.g. dopamine, nor-adrenaline, adrenaline, serotonin, gamma amino butyric acid (GABA) and glutamic acid and ions viz. sodium, potassium, and calcium has been studied in the presence of liquid membranes generated by THR and THE in association with sphingomyelin-cholesterol. The data on modifications in the permeability of relevant biogenic amines and ions indicate that the liquid membranes generated by THR may contribute to the mechanism of action of THR.

Hydroxyl radical formation resulting from the interaction of nickel complexes of L-histidine, glutathione or L-cysteine and hydrogen peroxide

L-histidine, L-cysteine, reduced glutathione (GSH) and other bioligands, which are ubiquitously present in biological systems, are recognized as antioxidants. Studies have shown that nickel (II) complexed with these ligands catalyzes the disproportionation of H2O2, leading to the generation of hydroxyl radicals (OH radical). However, none of the studies could provide information regarding effective concentrations at which these ligands act either as pro-oxidant or antioxidant. Therefore, the observed paradoxical behaviour of biological antioxidants in nickel-induced oxidative response was evaluated. Benzoic acid (BA) is hydroxylated by OH radical to form highly fluorescent dihydroxy benzoate (OH-BA). We used this model to study the effect of nickel complexes of L-histidine, GSH or L-cysteine on the hydroxylation of BA. The concentration-dependent effect of L-histidine, GSH and L-cysteine, or nickel on the hydroxylation of BA was studied. The hydroxylation of BA was significantly enhanced up to 1:0.5 molar ratio (Ni:hist or GSH). However, beyond 1:0.5 molar ratios, histidine/GSH inhibited the hydroxylation and complete inhibition was observed at 1:1 molar ratios. Sorbitol and caffeic acid, considered as scavengers of hydroxyl radicals, inhibited nickel-induced hydroxylation of BA. The present study demonstrates paradoxical behaviour of these bioligands. They act as pro-oxidant at lower ligand ratios and as antioxidant at higher ligand ratios. The redox properties of nickel complexes with histidine, GSH or cysteine reported here may be crucial for the toxicity of nickel.

Oscillatory phenomena at liquid–liquid interfaces

The mechanism of (i) Yoshikawa and Matsubara liquid-liquid interface oscillators and (ii) density/salt-water oscillators has been investigated. A modified simple mathematical formalism of both has been presented. Qualitative support for the model is provided by the available experimental results.

Scavenging action of zinc and green tea polyphenol on cisplatin and nickel induced nitric oxide generation and lipid peroxidation in rats

OBJECTIVE

Toxic metal ions have been implicated in the generation of reactive oxygen species (ROS) and nitric oxide (NO). Metallothionines (MT) and plant flavonoids have been reported in the intervention against oxidative damage. We investigated the effect of zinc induced MT and green tea polyphenol (GTP) in reducing the oxidative responses induced by nickel and platinum.

METHODS

Zinc (10 mg/kg b. wt, sc) was administered to rats twice at a gap of 24 hrs and GTP (10 mg/100 mL in drinking water) was fed ad libitum for 8 days. Nickel chloride (150 umol/kgb.wt, ip) and cisplatin (50 mumol/kg b.wt, sc) was administered to rats 24 h after Zn or GTP pre-treatment. Animals of all the groups were sacrificed 16 hrs after treatment and biochemical markers for toxicity were monitored.

RESULTS

Zinc or GTP pre-treatment caused significant protection against nickel or cisplatin enhanced mortality in rats, and reduction in lipid peroxidation and NO.

CONCLUSION

It is proposed that inhibition of ROS and NO by GTP and zinc may prove useful as a selective pharmacological agent in the amelioration of metal toxicity.

Blood zinc levels in children hospitalized with severe pneumonia: a case control study

A case control study was conducted in a referral and teaching hospital in North India on children aged 2 months to 5 years, to compare blood zinc levels in 50 cases of severe pneumonia and 50 age,sex and nutritional status matched controls. Mean blood Zinc levels in cases and controls was 376.1 ug/dL + 225.73 and 538.52 microg/dL +/- 228.0 respectively ( P value 0.0003). In logistic regression model severe pneumonia was associated with lower blood zinc level, use of biomass fuel and isolation of H. Influenzae from nasopharyngeal swab. Cotrimoxazole resistant S. pneumoniae were isolated from 95% of cases and 41.2 % of controls (P = 0. 0004). Therefore, the role of zinc in treatment of severe pneumonia should be investigated.

Single-capillary Teorell oscillator—studies with nonelectrolytes

It has been demonstrated that if in a Teorell oscillator, the membrane is replaced by a single capillary, the system behaves much better and becomes easily reproducible. It has also been demonstrated that oscillatory behavior in a Teorell-type setup is not limited to electrolytes; even nonelectrolytes can show oscillations. The only requirement seems to be that the nonelectrolyte should be capable of generating an electrical double layer in the capillary. This is the first report of a Teorell oscillator with a single capillary. Also, oscillations with nonelectrolytes in a Teorell-type setup have not been reported before.

Membrane oscillations involving electrokinetic phenomena

Semi theoretical models have been proposed to account for the mechanism of membrane oscillations involving, electrokinetic phenomena in systems where (i) concentration difference deltaC is finite and deltaP is varying but the current is fixed, and (ii) deltaC=0, pressure difference deltaP is fixed across the membrane and imposed current is fixed. The formalism leads to the van der Pol equation in both cases. Computer simulation has also been attempted, which indicates oscillations in the former case.

Inhibition of Japanese encephalitis virus infection by diethyldithiocarbamate is independent of its antioxidant potential

Diethyldithiocarbamate (DDTC), a low molecular weight dithiol, has been described as an immunomodulator and modifier of diverse biological actions in human and animal models, and has also been shown to be effective in several disease conditions. Therefore, we studied the therapeutic aspect of DDTC in providing inhibition of Japanese encephalitis virus (JEV) infection. DDTC tested at various doses (10-100 micromol/kg) revealed that administration at low concentration (10 micromol/kg; i.p.) on alternate days prolonged the average survival time (AST) of mice infected with lethal dose of JEV (102 LD50, i.c.) and delayed progression of the disease. The low dose also provided > 80% survival in sub-clinical (10(5) LD50, i.c.) JEV infection. Administration of DDTC to JEV-infected mice enhanced the inducible nitric oxide synthase (iNOS) activity in brain and level of serum tumour necrosis factor-alpha (TNF-alpha). We have recently demonstrated the production of nitric oxide (NO) via induction of iNOS activity is meditated by circulating macrophage-derived factor (MDF), which may be responsible for the delayed progression of the disease. DDTC-mediated inhibition of JEV is believed to involve the augmentation of protective role of MDF as evidenced by the observation that pretreatment with anti-MDF antibody significantly decreased the AST of mice and together with the inhibition of iNOS activity. Interestingly, DDTC alone did not stimulate iNOS and TNF-alpha in mock-infected normal mice. These results show that DDTC may have a possible therapeutic role during JEV infection.

Overview of results from the WaterTox intercalibration and environmental testing phase II program: part 2, ecotoxicological evaluation of drinking water supplies

Because of rapid population growth, industrial development, and intensified agricultural production increasing amounts of chemicals are being released into the environment, polluting receiving water bodies around the world. Given the potential health risk associated with the presence of toxicants in water sources used for drinking yet the scarcity of available data, there is a need to evaluate these waters and develop strategies to reduce and prevent their contamination. The present study examined the applicability of a battery of simple, inexpensive bioassays in environmental management and the relevance of the test results in establishing the toxicological quality of water sources and drinking water within the framework of the eight-country WaterTox Network, sponsored by the International Development Research Centre, Ottawa, Canada. Seventy-six samples were collected from surface and groundwater sources and seven samples from drinking water treatment plants. Each sample was tested with a core battery of bioassays (Daphnia magna, Hydra attenuata, and Lactuca sativa root inhibition tests) and a limited set of physical and chemical parameters. In addition, three labs included the Selenastrum capricornutum test. When no toxic effects were found with the battery, samples were concentrated 10x using a solid-phase extraction (SPE) procedure. Nonconcentrated natural water samples produced a toxic response in 24% of cases with all three core bioassays. When all bioassays are considered, the percentage of raw samples showing toxicity with at least one bioassay increased to 60%. Of seven treated drinkingwater samples, four showed toxicity with at least one bioassay, raising the possibility that treatment processes in these instances were unable to remove toxic contaminants. The Daphnia magna and Hydra attenuata tests indicated a high level of sensitivity overall. Although only three of the eight countries used S. capricornutum, it proved to be an efficient and reliable bioassay for toxicity assessment.

Overview of results from the WaterTox intercalibration and environmental testing phase II program: Part 1, statistical analysis of blind sample testing

There is an urgent need to evaluate the presence of toxicants in waters used for human consumption and to develop strategies to reduce and prevent their contamination. The International Development Research Centre undertook an intercalibration project to develop and validate a battery of bioassays for toxicity testing of water samples. The project was carried out in two phases by research institutions from eight countries that formed the WaterTox network. Results for the first phase were reported in the special September 2000 issue of Environmental Toxicology. Phase II involved toxicity screening tests of environmental and blind samples (chemical solutions of unknown composition to participating laboratories) using the following battery: Daphnia magna, Hydra attenuata, seed root inhibition with Lactuca sativa, and Selenastrum capricornutum. This battery was also used to assess potential toxicity in concentrated (10x) water samples. Results are presented for a set of six blind samples sent to the participating laboratories over a 1-year period. Analyses were performed for each bioassay to evaluate variations among laboratories of responses to negative controls, violations of test quality control criteria, false positive responses induced by sample concentration, and variability within and between labs of responses to toxic samples. Analyses of the data from all bioassays and labs provided comparisons of false positive rates (based on blind negative samples), test sensitivities to a metal or organic toxicant, and interlaboratory test variability. Results indicate that the battery was reliable in detecting toxicity when present. However, some false positives were identified with a concentrated soft-water sample and with the Lactuca and Hydra (sublethal end-point) tests. Probabilities of detecting false positives for individual and combined toxic responses of the four bioassays are presented. Overall, interlaboratory comparisons indicate a good reliability of the battery.

Interface-mediated oscillatory phenomena

Oscillatory transport processes which occur in the far from equilibrium region have assumed great significance from the viewpoint of science of complexity. Oscillatory phenomena in the chemical reaction systems have been subjected to intense investigations both from theoretical and experimental angles. In the present review an effort has been made to bring transport processes other than conventional chemical reactions into focus: transport processes mediated by solid-liquid and liquid-liquid interfaces have been discussed. Transport through membranes including liquid membranes, liquid-liquid interfaces and the recently reported hydrodynamic oscillator have been covered. Applications of these systems in areas such as fabrication of sensors, phase transfer catalysis and, of course, the obvious biological action, e.g. excitation of biomembranes and tissues, have been reviewed. Theoretical frameworks proposed to rationalize the phenomena have also been critically reviewed.

Nitric oxide production in Caco-2 cells exposed to different inducers, inhibitors and natural toxins

The involvement of the NO pathway in several intestinal inflammatory diseases is under investigation. In vitro models may provide a useful approach to better characterise this pathway at the cellular level. For this purpose, we have used Caco-2 cells, which are able to spontaneously differentiate in long-term culture to small intestine enterocytes. The effect of different NO pathway inducers [gamma-interferon (IFN-gamma) and phorbol myristate acetate (PMA)] has been studied. Our results demonstrate that Caco-2 cells constitutively express NOS at very low levels, while the induction with PMA+IFN-gamma triggers the expression of the inducible isoform with a stronger effect starting from day 14 of differentiation. The use of specific inhibitors of gene expression, at transcriptional and translational level, suggests that new synthesis of iNOS mRNA is required, through direct activation of the gene or new synthesis of transcription-required factors, as indicated by CHX inhibition. The morphological alteration induced by PMA+IFN-gamma is reversed by iNOS inhibitor, suggesting that the NO pathway may be involved in the cytoskeletal alterations. The DSP toxins, OA and DTX-1, induce NO production at levels corresponding to their different toxicity, previously detected in Caco-2 cells.

Induction of nitric oxide synthase during Japanese encephalitis virus infection: evidence of protective role

The ability of Japanese encephalitis virus (JEV) and JEV-induced macrophage-derived factor (MDF) to modulate nitric oxide synthase (NOS) activity in brain and tumor necrosis factor-alpha (TNF-alpha) and the possible antiviral role of NOS during JEV infection were investigated. NOS activity and particularly that of the inducible form of NOS (iNOS) was significantly enhanced in JEV or JEV-induced MDF-treated mice. Following JEV infection, total NOS activity in brain was gradually increased from Day 3 and reached a peak on Day 6. MDF-induced NOS activity and iNOS activity were dose dependent and maximum activity was observed at 1 h after treatment. The response was sensitive to anti-MDF antibody treatment and N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of NOS. Pretreatment of JEV-infected mice with L-NMMA increased the mortality as evident from reduced mean survival time (MST, 11.8 days) compared to placebo treated JEV-infected mice (MST, 17 days). The enhanced level of TNF-alpha observed in the early phase of JEV infection correlated well with the enhanced activity of iNOS. These observations thus provide evidence of the protective role of iNOS during JEV infection and indicate that iNOS may be a key mediator in host innate immune response to infection.

Green tea polyphenols and tannic acid act as potent inhibitors of phorbol ester-induced nitric oxide generation in rat hepatocytes independent of their antioxidant properties

The deleterious effects of excessive release of nitric oxide (NO) have been implicated in the tissue damage and inflammation. In this study, the effect of various flavonoids and other oxidant scavenging chemical agents have been studied for their ability to inhibit 12-O-tetradecanoyl phorbol 13-acetate (TPA)-induced NO generation in rat hepatocyte. Hepatocytes activated with TPA (25-200 nM) released NO in a concentration- and time-dependent manner. Green tea polyphenols (GTP) and tannic acid (TA) were most effective in inhibiting TPA-induced NO generation (90%). These agents were also effective in inhibiting NO formation when added 2 h following TPA addition. The other oxidant scavengers, such as L-histidine, sodium azide, vitamin E and sodium benzoate, were not found to be effective even up to 1.0 mM concentration. These results suggest that TA and GTP are potent inhibitors of NOS activity and the inhibition of TPA-induced NO generation by these polyphenols is independent of their antioxidant activity. It is tempting to speculate that these agents could be utilized in the pharmacological manipulations of NO-dependent pathophysiological responses.

Involvement of nitric oxide in nickel-induced hyperglycemia in rats

Nitric oxide is an important bioactive signaling molecule that mediates a variety of normal physiological functions which, if altered, could contribute to the genesis of many pathological conditions, including diabetes. In the present study we have shown the involvement of NO in nickel-induced hyperglycemia in male albino rats. Administration of nickel chloride (25 to 100 micromol/kg; ip) to overnight-fasted rats resulted in significant dose and time-dependent increase in plasma glucose, attaining maximum level at 1 h posttreatment and thereafter decreasing to normal levels by 4 h. The involvement of NO in nickel-induced hyperglycemia was evident by the observation that pretreatment of rats with NG-monomethyl-l-arginine (10 to 50 micromol/kg; ip), an inhibitor of nitric oxide synthase (NOS), significantly attenuated the nickel-mediated increase in the plasma glucose levels in a dose-dependent fashion. The activity of Ca(2+)-dependent NOS (constitutive form, c-NOS) was found to be significantly elevated in adrenals (5.5-fold) and brain (1.4-fold) at 1 and 2 h posttreatment, attaining normal levels by 4 h. In contrast, the activity of c-NOS in pancreas was significantly decreased (2.8-fold) with a concomitant increase (11.6-fold) in inducible NOS (i-NOS) at the same time interval. As observed by immunoblot analysis, a significant increase in i-NOS protein expression in the pancreas was observed at 1 and 2 h posttreatment. This was associated with a significant elevation in cGMP levels in adrenals, brain, and pancreas, possibly via the stimulation of cytosolic guanylate cyclase. This elevation in cGMP was abolished by low concentration of hemoglobin. These effects were associated with the accumulation of nickel in the target tissues. Taken together, our data suggest that nickel causes a significant increase in the levels of (i) cGMP and c-NOS in adrenals and brain and (ii) i-NOS in pancreas. These events may be responsible for modulating the release of insulin from pancreas finally leading to hyperglycemic condition in rats.

Synergistic effects in enzymic reactions

It has been shown that when two enzymes showing similar actions act in close proximity of each other they influence each other synergistically. The phenomenon of synergism is, however, not observed if the two enzymes are of dissimilar action type. The condition of closest proximity has been simulated by conducting the enzymic reactions inside the reversed micelles. In the present study we have experimented with alpha-amylase and invertase both hydrolysing enzymes and also with peroxidase and invertase which do not show similar actions.

Enzymic activity of whole cells entrapped in reversed micelles. Studies on alpha-amylase and invertase in the entrapped yeast cells

Studies have been conducted on the enzymic activity of Baker's yeast and also of Brewer's yeast entrapped into the reversed micelles formed by cetyl pyridinium chloride (CPC1) in n-hexane. The activities of alpha-amylase and invertase enzymes in the entrapped cells have been estimated and compared with those in the control experiments where there was no entrapment. The following significant observations have been made: 1. except for invertase, enzymes in Brewer's yeast, the entrapped yeast cells showed enhanced enzymic activities; 2. when the yeast cells were entrapped inside the reversed micelles along with substrates of the two enzymes, alpha-amylase, and invertase, the activity of each of these enzymes showed a further enhancement in comparison to that showed in the experiments in which substrates of the individual enzymes alone were entrapped-the phenomenon of synergism; 3. when the yeast cells and the respective substrates were entrapped inside separate reversed micelles and the solutions containing entrapped cells and entrapped substrates were mixed, the activities of the individual enzymes, alpha-amylase and invertase, showed further enhancement in comparison to the case in which the cells and the substrates were entrapped inside the same reversed micelle (in this case also the phenomenon of synergism was observed); and (4) In the case of experiments in which there was no entrapment, it was observed that the presence of substrates induced more release of enzymes from the yeast cells. These observations on yeast cells, which to the best of our knowledge have not been reported before, should be biotechnologically relevant.

Nitric oxide synthase and skin tumor promotion

Up-regulation of inducible form of nitric oxide (NO)-synthase and increased production of NO has been shown to occur in many pathological conditions associated with inflammatory responses. In this study we show that topical application of skin tumor promoters, which are known to produce inflammatory response, down-regulate the constitutive form of NO-synthase in SENCAR mouse epidermis. The phorbol type of tumor promoters viz 12-0-tetradecanoylphorbol-13-acetate (TPA) and mezerein produced greater inhibitory effects than the non phorbol tumor promoters viz anthralin, n-dodecane, benzoyl peroxide and okadaic acid. Pretreatment of the skin with a polyphenolic fraction isolated from green tea, which possesses strong antioxidant activity, almost completely restored the inhibitory response. We suggest that the constitutive NO-synthase activity may play an important role in tumor promoter-caused oxidative burst during the promotion stage of multistage skin carcinogenesis, and that antioxidants may also target their anti-tumor promoting effect via attenuating the NO-synthase pathway.

Metal-independent putative superoxide dismutase mimics in chemistry, biology, and medicine

The excessive generation of superoxide radicals O2-. with inadequate available defence provided by the enzyme superoxide dismutase (SOD) may result in the development and exacerbation of many of mankind's common illnesses. The native SOD proves too problematic to be used for the prevention and cure of such diseases. A number of metal-independent synthetic SOD mimics, based on organic nitroxides, have been tried as therapeutic interventions. Among the widely studied mimics, 2-ethyl-2,5,5-trimethyl-3-oxazolidinanyl, 2,2,6,6-tetramethyl-1-piperidimyloxy, nitrosoureas, and triazene derivatives have indicated promising results with possible future applications in chemistry, biology, and medicine.

Mimicking sensing mechanism of smell-oscillations of electrical potential difference across a bipolar liquid membrane induced by olfactory agents

Electrical potential oscillations across a bipolar liquid membrane, induced by olfactory agents have been reported. The data indicate that the bipolar liquid membrane system can be a good candidate for mimicking biological olfactory transduction.

Evidence for the involvement of nitric oxide in cisplatin-induced toxicity in rats

Cisplatin treatment of rats results into a significant increase in the activity of Ca(2+)-independent nitric oxide synthase (NOS) in kidneys and liver. Significant enhancement of lipid peroxidation in gastric mucosa, kidneys and liver was also observed. The administration of NG-nitro-L-arginine methyl ester, an inhibitor of NOS, markedly reduced renal and gastrointestinal toxicity, and also decreased the content of blood urea nitrogen, serum creatinine, and incidence of diarrhoea along with a significant inhibition in lipid peroxidation in the target organs. The present report, while demonstrating the beneficial effect of the blockade of NO pathways during cisplatin chemotherapy, may be helpful in developing strategies for combating some of the toxic side-effects of the drug.

Fungitoxic action of dithanes in presence of surfactant micelles

A rationale of arriving at the concentration of surfactant additives in the pesticidal formulations has been discovered. Fungitoxic activity of each of the two dithanes, Dithane M-45 (maneb) and Dithane Z-78 (zineb) has been estimated in the presence of various concentrations of three surfactants namely sodium lauryl sulphate, cetyl pyridinium chloride and Tween 80. Data reveal that the concentration of the surfactant additives in the pesticidal formulations should be at least equal to its critical micelle concentration (CMC) for enhanced biological activity. This rationale for the concentration of surfactant additives in the pesticidal formulation has so far not been clearly brought out in the literature. Since biological activity of the pesticides is enhanced in the presence of surfactant additives the present study is relevant to the reduction of environmental pollution due to pesticide residues.

Comparative evaluation of chelating agents on the mobilization of cadmium: a mechanistic approach

A comparative evaluation of chelating agents, namely, diethyl dithiocarbamate (DDC), dimethyl dithiocarbamate (DMDC), 1,4,8,11-tetraazacyclotetradecane (CYCLAM), 1,4,8,12-tetraazacyclopentadecane (TACPD), 2,3-dimercaptosuccinic acid (DMSA), and 2,3-dimercapto-1-propane sulfonate (DMPS) was conducted to assess their efficacy against acute cadmium (Cd) toxicity. DMSA and DMPS appeared to be most effective in reducing mortality as well as Cd burden of liver, kidneys, and brain in cadmium intoxicated mice. DMDC reduced Cd levels only in liver and kidneys, while DDC significantly enhanced its level in brain. CYCLAM and TACPD significantly increased the Cd level in liver and kidneys and were ineffective in brain. The therapeutic index as well as therapeutic efficacy was highest for DMSA followed by DMPS and DMDC. A fair degree of correlation was found to exist between (1) stability constant of Cd chelates and percent survival (r = .438, (2) stability constant and percent transport (r = .479), and (3) percent survival and percent transport (r =.447). However, the lipophilicity did not show any appreciable correlation with percent survival and stability constant of Cd chelates.

Reduction of cis-platinum induced nephrotoxicity by zinc histidine complex : the possible implication of nitric oxide

Cisplatin is a prominent member of the effective broad spectrum antitumor drugs. The clinical usage of cisplatin is, however, restricted due to some adverse side effects including renal toxicity. The present study demonstrates the protective effect of a Zinc-chelate of histidine, [Zn-Hist], against cisplatin induced nephrotoxicity and gastrointestinal toxicity as shown by decreases in BUN, creatinine and lower incidence of diarrhoea. The observed inhibition in cisplatin induced renal and hepatic lipid peroxidation by [Zn-Hist] pretreatment, suggests an importance for Zn in stabilisation of membrane integrity probably through the displacement of the redox-active metals that may be responsible for inducing peroxidative damage at target sites. The findings also suggest that cisplatin may play biochemical role in arginine-metabolism including nitric oxide (NO) production.

Exacerbation of nickel induced oxidative response by vitamin E

Vitamin E (alpha-tocopherol), a well known naturally occurring chain breaking antioxidant and a free radical scavenger was found to exacerbate nickel (Ni) toxicity in mice. Vitamin E (Vit. E) mediated enhancement of nickel toxicity was demonstrated by (i) enhanced mortality in mice treated with Ni and Vit. E (ii) increased hepatic lipid peroxidation, (iii) increased rate of benzoate hydroxylation, and (iv) liposomal membrane damage.

Efficacy of liposome encapsulated triethylenetetraamine hexaacetic acid (TTHA) against cadmium intoxication: role of lipid composition

Efficacy of Triethylenetetraamine hexaacetic acid (TTHA) encapsulated in liposomes having different lipid compositions was examined in animals pre-exposed to cadmium. Mice were injected with cadmium as cadmium (II) chloride 0.5 mg/kg b. wt. intraperitoneally daily for five days. Four weeks after the last injection of cadmium they were administered three injections of TTHA encapsulated in liposomes composed of either phosphatidyl choline:cholesterol (PC:Chol) or sphingomyelin:cholesterol (SM:Chol) in 1:1 molar ratio at a gap of 48 h. Urinary and fecal elimination of cadmium and its distribution in liver, kidneys and spleen were examined. Treatment with TTHA encapsulated in liposomes mobilized higher amount of cadmium from liver and spleen. The overall efficiency for cadmium mobilization was better in TTHA encapsulated in SM:Chol liposome treated group which also led to enhanced excretion of cadmium through urine and feces. The results indicate that TTHA encapsulated in SM:Chol liposomes exhibited highest efficacy in mobilizing cadmium from the body of pre-exposed mice followed by PC:Chol liposomes and the free drug.

Activation and stabilization of enzymes entrapped into reversed micelles. Studies on hydrolyzing enzymes--protease and alpha-amylase

Observations of the activity of two hydrolyzing enzymes-protease and alpha-amylase--entrapped inside the reversed micelles formed by surfactants in hexane, benzene, and cyclohexane are reported. The surfactants chosen for this study are: Tween 80, a nonionic surfactant, Cetyl pyridinium chloride, a cationic surfactant, and two anionic surfactants, sodium lauryl sulfate and Aerosol OT. Tween 80 enhances the activity of both protease and alpha-amylase. Sodium lauryl sulfate and Aerosol OT, which are ionic surfactants, enhance the activity of protease, but inhibit the activity of alpha-amylase. Cetyl pyridinium chloride, however, enhances the activity of alpha-amylase, but inhibits the activity of protease. Enhanced activity is generally severalfold greater in comparison to the activity observed in the usual aqueous system in the absence of reversed micelles. It has also been observed that the enhanced activity of the enzymes entrapped inside the reversed micelles remains preserved for a much longer period of time in comparison to the activity in the usual aqueous systems. These observations, which support the view that with proper choice of surfactant and the organic solvent, reversed micelles act like a microreactor that provides a favorable aqueous micro-environment for enzyme activity, have biotechnological overtones.

Protective role of metallothionein in nickel induced oxidative damage

Recent studies have focussed on the role of thiol rich proteins especially metallothionein (MT) in the therapeutic interventions against oxidative damage. In our previous communication we showed that reactive oxygen species arising via Fenton's reactions are the proximal lipid oxidant during nickel-toxicity. The purpose of the present communication is to evaluate the role of zinc, cadmium or silver-metallothioneins on the protection against nickel-induced peroxidative damage. Our results demonstrate that Zn-MT provided maximum protection against nickel-induced mortality in mice and also served as an efficient antagonist in inhibiting nickel-mediated lipid peroxidation compared to Cd-MT or Ag-MT. Zn-MT also provided protection against iron (II)-ascorbate induced microsomal lipid peroxidation and reversed nickel-mediated inhibition of calcium sequenstration. We conclude that Zn-MT could serve as an excellent physiological antioxidant against nickel-mediated oxidative.

Influence of size of liposomes in potentiating the efficacy of encapsulated triethylenetetramine-hexaacetic acid (TTHA) against cadmium intoxication

Polyaminocarboxylic acids have widely been used an antidotes in heavy metal intoxication, however their hydrophilic nature renders them to be mostly distributed extracellularly. To facilitate the intracellular delivery of such chelating agent, triethlenetetraamine-hexaacetic acid (TTHA) was encapsulated in small unilamellar vesicles (SUV) or dehydration rehydration vesicles (DRV) and its effect was examined in the amelioration of cadmium toxicity. Mice were administered cadmium (0.2 mg/kg B.wt.) as CdCl2 intraperitoneally daily for five days. After a period of four weeks rest. they were given two intravenous injections of TTHA as free material or encapsulated in liposomes (0.16 m mole/kg) at a gap of 48 hours. Urinary and fecal elimination of cadmium and its distribution in the liver, kidney and spleen was monitored after TTHA treatment. The results indicate the efficacy of TTHA in removing cadmium from the body organs of preexposed animals and its excretion through urine and feces was maximum when it was encapsulated in SUV liposomes.

Mobilization of cadmium by liposome-encapsulated meso-2,3-dimercaptosuccinic acid in pre-exposed mice

meso-2,3-Dimercaptosuccinic acid (DMSA) treatment in free of liposome-encapsulated form was given to mice pre-exposed to cadmium as CdCl2 (2 intraperitoneal injections; 0.5 mg Cd/kg along with 5 microCi 109CdCl2 in 4 ml volume within 24 h). Both treatments removed cadmium from liver, spleen, testis and blood with liposomal DMSA exhibiting higher efficacy in mobilizing cadmium not only from whole organs but also from liver proteins. It also resulted in higher excretion of cadmium via urine as compared with free DMSA or saline treatment. Whereas this treatment eliminated significantly higher amounts of cadmium via the fecal route throughout the period examined, free DMSA responded only 48 h after treatment and was less effective. The results suggest mobilization of cadmium from intracellular sites of deposition. However, DMSA in the dose administered (24 mumol/kg i.v.) in either form was ineffective in decorporating cadmium from the kidney, the critical organ in cadmium intoxication.

Modulation of liposomal lipid peroxidation in presence of nickel by incorporation of alpha-tocopherol in the bilayer

alpha-Tocopherol is a well-known membrane associated chain-breaking phenolic antioxidant which functions as a trap for peroxyl and other free radicals and thus inhibits lipid peroxidation of membranes. Antioxidative effect of alpha-tocopherol when incorporated in liposomes was examined by the generation of Thiobarbituric acid (TBA) reacting species in the presence of nickel. The incorporation of alpha-tocopherol in the lipid bilayer resulted in the enhancement of lipid peroxidation at low concentration (1.0 mg) but at higher concentration (2.5 and 5.0 mg) considerably reduced the enhancement in lipid peroxidation of liposomes in the presence of nickel. When alpha-tocopherol was added (unincorporated) to liposomes in the presence of nickel, enhancement in lipid peroxidation was observed compared to nickel alone. Thus the antioxidative effect of alpha-tocopherol in the liposomes may depend on its mode of incorporation in the lipid bilayer.

Liquid membrane phenomenon in the actions of digitalis

The liquid membrane phenomenon in the actions of digitalis glycosides (digitoxin, digoxin and ouabain) has been studied. Formation of liquid membranes, in series with a supporting membrane, by digitalis alone and by digitalis in association with lecithin and cholesterol has been demonstrated. The results obtained on the transport of relevant permeants, viz. sodium, potassium and calcium ions and dopamine, adrenaline, noradrenaline and serotonin, in the presence of the liquid membrane generated by digitalis in association with lecithin and cholesterol indicate that the liquid membrane barrier to transport may have a relevance with the biological actions of digitalis.

Crystal structure of form II of cholesteryl palmitelaidate at 295 K

Form II for cholesteryl palmitelaidate (trans-9-hexadecenoate) (C43H74O2) is monoclinic P2(1) with a = 12.745(3), b = 9.006(2), c = 18.153(4) A, beta = 96.63 (2) degrees, Z = 2. The X-ray crystal structure of form II has been determined from 2506 reflections of which 2126 gave (F greater than 2 sigma). The data up to sin theta/lambda = 0.44A-1 (Dmin = 1.14 A) were measured with CuK alpha radiation from a sealed tube. These were supplemented up to sin theta/lambda = 0.52 A-1 (Dmin = 0.96 A) by measurements on the same crystal using a rotating anode X-ray source. The electron density was diffuse in the ester chain and the atoms of the cholesteryl tail were found to be disordered. The tail and the chain atoms were refined by restrained least squares methods to give R = 0.087 and Rw = 0.10 for reflections with F greater than 2 sigma. Crystal forms I and II represent two standard structure types already characterized for fatty acid esters of cholesterol. In form II, the ester chain is almost fully extended as is also the case for one of the two independent molecules (A) in form I. In form II, the chains pack loosely together for most of their length. M.s. amplitudes of thermal vibration for the chain C-atoms are almost uniform along the entire chain (approximately 0.25 A2 at 295 K). In form I, the proximal part of the A chain is surrounded by rigid cholesteryl groups. In this region, C-atom m.s. amplitudes are much reduced (approximately 0.10 A2) but they increase to about 0.5 A2 at the distal end of the chain where packing is very loose.

Role of liquid membrane phenomenon in the biological actions of prostaglandins: studies on prostaglandin E1 and prostaglandin F2 alpha

Modifications in the transport of relevant permeants to their respective sites of action due to the liquid membranes formed by prostaglandins in association with lecithin and cholesterol have been discussed in the light of biological actions of prostaglandins. It has been shown that the phenomenon of liquid membrane formation is likely to make a significant contribution to the biological actions.

Liquid membrane phenomenon in the biological actions of benzodiazepines

The liquid membrane phenomenon in benzodiazepines has been studied. Transport of glycine, GA-BA, noradrenaline, dopamine and serotonin in the presence of the liquid membranes generated by the benzodiazepines in association with lecithin and cholesterol has been studied. The data indicate that modification in permeabilities in the presence of the liquid membranes is likely to make a significant contribution to several biological actions of the benzodiazepines.

Alleviation of nickel-induced biochemical alterations by chelating agents

The effect of 1,4,8,11-tetraazacyclotetradecane (Cyclam), triethylenetetramine (TETA), reduced glutathione (GSH), ethylenediamine tetraacetic acid (EDTA), cyclohexanediamine tetraacetic acid (CDTA), diethylene triamine pentaacetic acid (DTPA), and hydroxyethylenediamine triacetic acid (HEDTA) on the alleviation of nickel-induced biochemical and trace-metal alterations in serum, liver, and kidney of nickel-treated rats was studied. The lipophilic chelating agents Cyclam and TETA exhibited a higher order of effectiveness in alleviating nickel-induced alterations compared to EDTA, CDTA, DTPA, and HEDTA, the hydrophilic chelating agents. The higher efficacy of lipophilic agents may be due to their ability to bind to nickel present in extracellular fluid as well as in intracellular fluid, while the hydrophilic agents may bind only to nickel present in extracellular fluid. Our data also suggest that the efficacy of Cyclam to ameliorate nickel-induced alterations is exceptionally high.

Evidence for the involvement of hydroxyl radicals in nickel mediated enhancement of lipid peroxidation: implications for nickel carcinogenesis

The administration of nickel to rats resulted in enhanced hepatic lipid peroxidation, levels of glutathione and iron with a concomitant decrease in glutathione peroxidase activity. These effects were dose dependent. Enhanced lipid peroxidation was found to be inhibited by the exogenous addition of ethylenediamine tetraacetic acid (EDTA), benzoate and ethanol while catalase and superoxide dismutase were ineffective in this regard. Our data strongly suggest the involvement of hydroxyl radicals in the nickel mediated enhancement of lipid peroxidation which may have their implications in the carcinogenicity of nickel compounds.