Abstract  Multidrug resistance (MDR) is a major impediment to the success of cancer chemotherapy. Through the development of a drug delivery system that tethers doxorubicin onto the surface of gold nanoparticles with a poly(ethylene glycol) spacer via an acid-labile linkage (DOX-Hyd@AuNPs), we have demonstrated that multidrug resistance in cancer cells can be significantly overcome by a combination of highly efficient cellular entry and a responsive intracellular release of doxorubicin from the gold nanoparticles in acidic organelles. DOX-Hyd@AuNPs achieved enhanced drug accumulation and retention in multidrug resistant MCF-7/ADR cancer cells when it was compared with free doxorubicin. It released doxorubicin in response to the pH of acidic organelles following endocytosis, opposite to the noneffective drug release from doxorubicin-tethered gold nanoparticles via the carbamate linkage (DOX-Cbm@AuNPs), which was shown by the recovered fluorescence of doxorubicin from quenching due to the nanosurface energy transfer between the doxorubicinyl groups and the gold nanoparticles. DOX-Hyd@AuNPs therefore significantly enhanced the cytotoxicity of doxorubicin and induced elevated apoptosis of MCF-7/ADR cancer cells. With a combined therapeutic potential and ability to probe drug release, DOX-Hyd@AuNPs represent a model with dual roles in overcoming MDR in cancer cells and probing the intracellular release of drug from its delivery system.

Abstract  The aim was to develop a new up-to-date and comprehensive job exposure matrix (JEM) for estimating exposure to potential endocrine disruptors in epidemiological research.

Chemicals with endocrine disrupting properties were identified from the literature and classified into 10 chemical groups: polycyclic aromatic hydrocarbons (PAHs), polychlorinated organic compounds, pesticides, phthalates, organic solvents, bisphenol A, alkylphenolic compounds, brominated flame retardants, metals and a miscellaneous group. Most chemical groups were divided into three to six subgroups. Focusing on the years 1996-2006, three experts scored the probability of exposure to each chemical group and subgroup for 353 job titles as "unlikely" (0), "possible" (1) or "probable" (2). Job titles with positive exposure probability scores were provided with exposure scenarios that described the reasoning behind the scores.

Exposure to any chemical group was unlikely for 238 job titles (67%), whereas 102 (29%) job titles were classified as possibly (17%) or probably (12%) exposed to one or several endocrine disruptors. The remaining 13 job titles provided too little information to classify exposure. PAHs, pesticides, phthalates, organic solvents, alkylphenolic compounds and metals were often linked to a job title in the JEM. The remaining chemical groups were found to involve very few occupations.

Despite some important limitations, this JEM could be a valuable tool for exposure assessment in studies on the health risks of endocrine disruptors, especially when task specific information is incorporated. The documented exposure scenarios are meant to facilitate further adjustments to the JEM to allow more widespread use.

Abstract  Here we describe two cases of carbamate poisoning. Patients AMF and PVM were accidentally poisoned by cholinesterase inhibitors. The medical diagnosis in both cases was overcholinergic syndrome, as demonstrated by exposure to cholinesterase inhibitors. The widespread use of cholinesterase inhibitors, especially as pesticides, produces a great number of human poisoning events annually. The main known neurotoxic effect of these substances is cholinesterase inhibition, which causes cholinergic overstimulation. Once AMF and PVM had recovered from acute intoxication, they were subjected to extensive neuropsychological evaluation 3 and 12 months after the poisoning event. These assessments point to a cognitive deficit in attention, memory, perceptual, and motor domains 3 months after intoxication. One year later these sequelae remained, even though the brain magnetic resonance imaging (MRI) and computed tomography (CT) scans were interpreted as being within normal limits. We present these cases as examples of neuropsychological profiles of long-term sequelae related to acute poisoning by cholinesterase inhibitor pesticides and show the usefulness of neuropsychological assessment in detecting central nervous system dysfunction in the absence of biochemical or structural markers.

Abstract  We have developed a method for simultaneous analysis of methylcarbamate pesticides in serum with an acute pesticide intoxication. This is performed by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. Rapid detection of eight types of methylcarbamate pesticide can be achieved with this method, it only requires an extremely simple pre-treatment of the sample. The specificity of this method is equal to that of gas chromatography-mass spectrometry, and it satisfies the clinical requirements for detection sensitivity and specificity. Although some problems with this analytical method remain to be solved, we consider it to be superior to any other analytical method previously reported.

Abstract  Abstract: The multifunctional, anti-Alzheimer drug, ladostigil (TV3326) [(N-propargyl-(3R) aminoindan-5yl)-ethyl methyl carbamate] combines the neuroprotective effects of the anti-Parkinson drug, rasagiline, a selective monoamine oxidase (MAO)-B inhibitor, with the cholinesterase (ChE) inhibitory activity of rivastigmine in a single molecule. Ladostigil has been shown to possess potent antiapoptotic and neuroprotective activities in various oxidative insults in vitro and in vivo, such as prevention of the fall in mitochondrial membrane potential and regulation of Bcl-2 family proteins. In the present study, we demonstrate that ladostigil (1μM) increased cell viability, associated with the increase of catalase activity and decrease of intracellular reactive oxygen species (ROS) production in human SH-SY5Y neuroblastoma cells exposed to (hydrogen peroxide) H2O2. Furthermore, ladostigil significantly elevated mRNA levels of the antioxidants enzymes, catalase, NAD(P)H quinone oxidoreductase 1 (NQO1) and peroxiredoxin 1 (Prx 1) in H2O2-treated SH-SY5Y cells. Chronic treatment with ladostigil (1mg/kg gavage per day for 30 days) markedly up-regulated mRNA expression levels of various antioxidant enzymes in aged rat hippocampus (e.g. glutathione peroxidase precursor (GSHPX-P), glutathione S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PD)). These findings indicate that in addition to its multiple neuroprotective characteristics, ladostigil also possesses antioxidant properties, which might be beneficial for the treatment of oxidative stress (OS) in aging and age-associated neurodegenerative diseases. [Copyright 2008 Elsevier] Copyright of Chemico-Biological Interactions is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)

Abstract  A high-performance liquid chromatographic (HPLC) assay for methyl 5-hydroxy-2-benzimidazole carbamate (5-HBC) in urine was developed in order to assess the exposure of workers to the pesticide carbendazim. 5-HBC is measured in urine after hydrolysis, sample clean-up through a strong cation-exchange (SCX) column and extraction with ethyl acetate. HPLC with electrochemical detection provides selective and sensitive determination of 5-HBC with a detection limit of 5 μg/l. A C18 reversed-phase column was used with 0.06 M ammonium acetate solution (pH 8)—methanol (73:27) as mobile phase. The method was validated with respect to hydrolysis of urine samples, analytical recovery of spiked 5-HBC, stability of 5-HBC conjugates, limit of detection, background and precision. The overall analytical recovery from urine was better than 60%. 5-HBC, excreted in urine as a conjugate, was stable for at least one year when stored at − 20°C. A background of ca. 5 μg/l was detected in urine from some non-occupationally exposed persons. Between-day coefficients of variation as calculated from the results of the stability test were 7, 4 and 4% for concentrations of 61, 244 and 295 μg/l 5-HBC, respectively (n = 16).

Abstract  Microcystins are among the most commonly detected toxins associated with cyanobacteria blooms worldwide. Two episodes of intravenous microcystin exposures occurred among kidney dialysis patients during 1996 and 2001. Analysis of serum samples collected during these episodes suggests that microcystins are detectable as free and bound forms in human serum. Our goal was to characterize the biochemical evidence for human exposure to microcystins, to identify uncertainties associated with interpretation of these observed results, and to identify research needs. We analyzed serum samples using enzyme-linked immunosorbent assay (ELISA) methods to detect free microcystins, and gas chromatography/mass spectrometry (GC/MS) to detect 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB). MMPB is derived from both free and protein-bound microcystins by chemical oxidation, and it appears to represent total microcystins present in serum. We found evidence of free microcystins in patient serum for more than 50 days after the last documented exposure. Serum concentrations of free microcystins were consistently lower than MMPB quantification of total microcystins: free microcystins as measured by ELISA were only 8-51% of total microcystin concentrations as detected by the GC/MS method. After intravenous exposure episodes, we found evidence of microcystins in human serum in free and protein-bound forms, though the nature of the protein-bound forms is uncertain. Free microcystins appear to be a small but variable subset of total microcystins present in human serum. Research is needed to elucidate the human toxicokinetics of microcystins, in part to determine how observed serum concentrations can be used to estimate previous microcystin exposure. (c) 2007 Wiley Periodicals, Inc.

Abstract  #The induction of sister chromatid exchanges (SCE) and mutation at the hypoxanthine-guanine phosphoribosyl transferase locus and toxicities of 40 different chemical and physical agents were examined on Chinese hamster V79 cells. These agents included mono-, di-, tri-, and polyfunctional alkylating agents, intercalators, -rays, and UV light irradiation. Mutation was measured as resistance to 6-thioguanine and toxicity as loss of cell-plating efficiency. SCE were examined 29 hr after treatment. With the agents examined, a highly positive correlation (r = 0.89) exsisted between SCE-inducing and mutagenic potencies, when expressed as increase in the number per a unit dose over the control values. But the great difference of the ratios of mutagenic potencies versus SCE-inducing potencies among agents was observed, the maximal difference in the ratios being about 200-fold. The agents that showed the higher values of the ratio (agents producing more mutations than SCE) were bleomycin, cobalt-60 -rays, all ethylating agents (N-ehtyl-N-nitrosourea, N-ethyl-N'-nitro-N-nitrosoguanidine, ethyl methanesulfonate, and diethylsulfate), N-propyl-N-nitrosourea, N-butyl-N-nitrosourea, isopropyl methanesulfonate, intercalating acridine compounds (2-methoxy-6-chloro-9-[3-(ethyl-2-chloroethyl)aminopropylamino]-acridineÀ2HCI and 2-methoxy-6-chloro-9-[3-(chloroethyl)-aminopropylamino]acridine 2HCI) and UV light at 254 nm. The agents that showed the lower values (agents producing more SCE than mutations) were platinum compounds (cis-diamminedichloroplatinum and trans-diamminedichloroplatinum), epoxides (epichlorohydrin, styrene oxide, and diepoxybutane) and aziridines (mitomycin C, decarbamoyl mitomycin C, tris(1-aziridinyl)phosphine sulfide, triethylenemelamine, and carboquone). The agents that showed the intermediate values included all methylating agents (N-methyl-N-nitrosourea, N-methyl-N'-nitro-N-nitrosoguanidine, methyl methanesulfonate, and dimethyl sulfate), N-(2-hydroxyethyl)ethyleneimine, ▀-propiolactone, treatment of 8-methoxypsoralen plus near-UV light irradiation at 352 nm, 4-nitroquinoline-1-oxide, quinacrine mustard, sodium sorbate, cigarette tar, and diesel tar. For most agents that induced SCE, the toxicity dependency of induced SCE was rather biphasic; increase in SCE was steep at low to moderate toxicity and less at moderate to high toxicity. At equitoxic doses, the agents showed great difference in induction of SCE.

Abstract  Background: Whereas a number of studies have investigated the putative role of environmental toxins in the pathogenesis of idiopathic Parkinson disease, the possibility of such a role in multiple system atrophy has received little attention. Design and Setting: Review of records of patients examined in the Parkinson's Disease Center and Movement Disorder Clinic, Baylor College of Medicine, Houston, Tex, from July 1, 1977, to February 4, 1998. Patients: We reviewed 100 consecutive medical records of patients who satisfied the diagnostic criteria for multiple system atrophy formulated by the Consensus Committee of the American Autonomic Society and the American Academy of Neurology. Intervention: The type and amount of toxin exposure were verified by history and examination of records whenever possible. Severity of parkinsonism was assessed by clinical rating scales. Main Outcome Measure: Development of multiple system atrophy after environmental toxin exposure. Results:

Abstract  Spinal cord ischemia with resulting paraplegia remains one of the most common complications after repair of thoracoabdominal aortic aneurysms or dissection. Inducible nitric oxide synthase (iNOS) is known to have both neuroprotective and neurotoxic effects in the central nervous system. We investigated the possible relationship between the effect of pre-ischemic isoflurane exposure on mild spinal cord ischemia and the inducible nitric oxide synthase (iNOS) expression by using iNOS-specific antibody and pyrrolidinedithio carbamate (PDTC), NF-kappaB inhibitor, in the ventral horn of spinal cord in rats.

The animals were divided into five groups (n = 6 in each group): sham group, control group, PDTC-treated group, isoflurane-treated group, and PDTC/ isoflurane-treated group. In the PDTC-treated groups, 2% 100 mg/kg PDTC was administered intraperitoneally at 1 h before operation and at 24 h and 48 h after reperfusion. The rats in the isoflurane-treated groups received 30 min inhalation of 2.8% isoflurane at 24 h before spinal cord ischemia. Immunohistochemistry was performed to detect iNOS expression in the motor neuron of the ventral horn in spinal cord.

Preconditioning with isoflurane increased the iNOS expression when compared to the control group (P < 0.05), whereas pre-treatment with both PDTC and isoflurane significantly decreased the iNOS expression compared to isoflurane-treated group (P < 0.05).

Pre-ischemic isoflurane exposure was related with increase of the iNOS expression via a pathway modulated by NF-kappaB. iNOS may act as an important mediator of delayed preconditioning with isoflurane for the protective effect against spinal cord ischemia.

Abstract  An amperometric biosensor for highly selective and sensitive determination of methyl parathion (MP) was developed based on dual-signal amplification: (1) a large amount of introduced enzyme on the electrode surface and (2) synergistic effects of nanoparticles towards enzymatic catalysis. The fabrication process includes (1) electrochemical deposition of gold nanoparticles by a multi-potential step technique at multiwalled carbon nanotube (MWCNT) film pre-cast on a glassy carbon electrode and (2) immobilization of methyl parathion degrading enzyme (MPDE) onto a modified electrode through CdTe quantum dots (CdTe QDs) covalent attachment. The introduced MWCNT and gold nanoparticles significantly increased the surface area and exhibited synergistic effects towards enzymatic catalysis. CdTe QDs are further used as carriers to load a large amount of enzyme. As a result of these two important enhancement factors, the proposed biosensor exhibited extremely sensitive, perfectly selective, and rapid response to methyl parathion in the absence of a mediator. The detection limit was 1.0 ng/mL. Moreover, since MPDE hydrolyzes pesticides containing the P-S bond, it showed high selectivity for detecting MP and many interfering compounds, such as carbamate pesticides. Other organophosphorous pesticides and oxygen-containing inorganic ions (SO(4)(2-), NO(3)(-)) did not interfere with the determination. The proposed MPDE biosensor presents good reproducibility and stability, and the MPDE is not poisoned by organophosphate pesticides. Unlike cholinesterase-based biosensor, the MPDE biosensor can be potentially reused and is suitable for continuous monitoring.

Abstract  In the title compound, C(13)H(11)NO(2), the aromatic rings are oriented at a dihedral angle of 42.52 (12)°. The crystal structure is stabilized by inter-molecular N-H⋯O hydrogen bonds, which form infinite one-dimensional polymeric chains extending along the a axis. C-H⋯π inter-actions between the aromatic rings are also present.

Abstract  In the title compound, C(13)H(17)NO(2), the dihedral angle between the benzene ring and the basal plane of the cyclo-hexyl ring is 49.55 (8)°. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming chains propagating in [010].

Abstract  The liver represents one of the major sites of human glucuronidation. Many therapeutic drugs are substrates for UDP-glucuronosyltransferases (UGT) leading to the formation of usually inactive glucuronides. Hepatic glucuronidation undergoes significant changes during fetal and neonatal development requiring age adapted drug therapy. Regulation of individual UGT genes during hepatic development has not been defined.

Expression of 13 UGT genes and glucuronidation activities were analysed in 16 paediatric liver samples (aged 7-24 months), two fetal samples, and 12 adult liver samples (aged 25-75 years) using duplex reverse transcription-polymerase chain reaction, western blot, and specific catalytic UGT activity assays.

No UGT transcripts were detected in fetal liver at 20 weeks' gestation. In contrast, UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9, UGT2B4, UGT2B7, UGT2B10, and UGT2B15 transcripts were present without variation in all 28 hepatic samples after six months of age. Significantly lower expression of UGT1A9 and UGT2B4 mRNA was identified in paediatric liver. Hepatic glucuronidation activity in children aged 13-24 months was found to be lower than in adults for ibuprofen (24-fold), amitriptyline (16-fold), 4-tert-butylphenol (40-fold), estrone (15-fold), and buprenorphine (12-fold).

An early phase characterised by the appearance of UGT gene transcripts and a later phase characterised by upregulation of UGT expression is demonstrated during human hepatic development. The differential regulation of UGT1A9 and UGT2B4 expression extends beyond two years of age and is capable of influencing hepatic glucuronidation of common therapeutic drugs in children. The development of hepatic UGT activities is significant for paediatric drug therapy and the prevention of adverse drug effects.

Abstract  In the title carbamate compound, C(17)H(23)NO(2), one of the Csp(3) atoms of the cyclo-hexene ring is disordered over two sites with refined occupancies of 0.55 (2) and 0.45 (2), both disorder components resulting in half-boat conformations. The mean plane through the carbamate unit is inclined at inter-planar angles of 14.80 (13), 18.30 (17) and 24.0 (2)°, respectively, with respect to the phenyl ring, and the major and minor disorder component cyclo-hexene rings. In the crystal structure, adjacent mol-ecules are linked into chains along [001] via inter-molecular N-H⋯O hydrogen bonds. The crystal structure is further stabilized by weak inter-molecular C-H⋯π inter-actions.

Abstract  Preclinical studies, along with Phase I, II, and III clinical trials demonstrate the pharmacokinetics, pharmacodynamics, safety and efficacy of a new drug under well controlled circumstances in relatively homogeneous populations. However, these types of studies generally do not answer important questions about variability in specific factors that predict pharmacokinetic and pharmacodynamic (PKPD) activity, in turn affecting safety and efficacy. Semi-physiological and clinical PKPD modeling and simulation offer the possibility of utilizing data obtained in the laboratory and the clinic to make accurate characterizations and predictions of PKPD activity in the target population, based on variability in predictive factors. Capecitabine is an orally administered pro-drug of 5-fluorouracil (5-FU), designed to exploit tissue-specific differences in metabolic enzyme activities in order to enhance efficacy and safety. It undergoes extensive metabolism in multiple physiologic compartments, and presents particular challenges for predicting pharmacokinetic and pharmacodynamic activity in humans. Clinical and physiologically based pharmacokinetic (PBPK) and pharmacodynamic models were developed to characterize the activity of capecitabine and its metabolites, and the clinical consequences under varying physiological conditions such as creatinine clearance or activity of key metabolic enzymes. The results of the modeling investigations were consistent with capecitabine's rational design as a triple pro-drug of 5-FU. This paper reviews and discusses the PKPD and PBPK modeling approaches used in capecitabine development to provide a more thorough understanding of what the key predictors of its PBPK activity are, and how variability in these predictors may affect its PKPD, and ultimately, clinical outcomes.

Abstract  A simple and green method was developed for in situ assembly of gold nanoparticles on nitrogen-doped carbon nanotubes, and the resulting Au/nitrogen-doped carbon nanotubes nanocomposite was used as an immobilization scaffold of antibody for sensitive immunosensing of microcystin-LR.

Abstract  This communication demonstrates superparamagnetic nano-sized particles with amagnetic core and a porous carbon shell (thickness of 11 nm), which can remove 97% of Pb2+ ions from an acidic aqueous solution at a Pb2+ ion concentration of 100 mg L-1. It is suggested that a weak electrostatic force of attraction between the heavy metal ions and the nanoparticles and the heavy metal ions adsorption on the mesopore carbon shell contribute most to the superior removal property.

Abstract  Three 5,5'-dicarbamate-2,2'-bipyridine ligands (L = L(1)-L(3)) bearing ethyl, isopropyl or tert-butyl terminals, respectively, on the carbamate substituents were synthesized. Reaction of the ligands L with the transition metal ions M = Fe(2+), Cu(2+), Zn(2+) or Ru(2+) gave the complexes ML(n)X(2)·xG (1-12, n = 1-3; X = Cl, NO(3), ClO(4), BF(4), PF(6), ½SO(4); G = Et(2)O, DMSO, CH(3)OH, H(2)O), of which [Fe(L(2))(3) ⊃ SO(4)]·8.5H(2)O (2), [Fe(L(1))(3) ⊃ (BF(4))(2)]·2CH(3)OH (7), [Fe(L(2))(3) ⊃ (Et(2)O)(2)](BF(4))(2)·2CH(3)OH (8), [ZnCl(2)(L(1))][ZnCl(2)(L(1))(DMSO)]·2DMSO (9), [Zn(L(1))(3) ⊃ (NO(3))(2)]·2H(2)O (10), [Zn(L(2))(3) ⊃ (ClO(4))(Et(2)O)]ClO(4)·Et(2)O·2CH(3)OH·1.5H(2)O (11), and [Cu(L(1))(2)(DMSO)](ClO(4))(2)·2DMSO (12) were elucidated by single-crystal X-ray crystallography. In the complexes ML(n)X(2)·xG the metal ion is coordinated by n = 1, 2 or 3 chelating bipyridine moieties (with other anionic or solvent ligands for n = 1 and 2) depending on the transition metal and reaction conditions. Interestingly, the carbamate functionalities are involved in hydrogen bonding with various guests (anions or solvents), especially in the tris(chelate) complexes which feature the well-organized C(3)-clefts for effective guest inclusion. Moreover, the anion binding behavior of the pre-organized tris(chelate) complexes was investigated in solution by fluorescence titration using the emissive [RuL(3)](2+) moiety as a probe. The results show that fluorescent recognition of anion in solution can be achieved by the Ru(II) complexes which exhibit good selectivities for SO(4)(2-).

Abstract  Since no attempt has been made so far in India to determine isopropyl N-(3-chlorophenyl) carbamate (CIPC) residues in potatoes, it became necessary to determine its residues in potatoes which are being used for table and processing purposes. Using high-performance liquid chromatography, CIPC residues were determined in peels, peeled tubers and unpeeled tubers periodically during storage at 10-12 degrees C in commercial cold stores. The highest concentration of CIPC found in potato peels was 20.17 mg/kg fresh wt, whereas in unpeeled and peeled tubers the residue levels were very low ranging from 0.29 to 1.13 and 0.05 to 0.24 mg/kg, respectively. However, all residue levels observed were within the maximum residue level prescribed by the US Environmental Protection Agency. The experiments done to determine the dispersal and concentration of CIPC applied as an aerosol fog with respect to location and time showed that the distribution of CIPC within the cold store was uneven leading to large variations in residue levels in samples drawn from different parts of the store.

Abstract  Selective hydrogenation of benzonitrile was studied with Ni/Al 2O3 in compressed CO2, hexane-CO2, ethanol-CO2 and H2O-CO2 systems. The phase behavior and the effect of CO2 on the conversion of benzonitrile and the yield of benzylamine were discussed. The reaction rate was retarded in solventless, hexane and ethanol, but accelerated in water in the presence of compressed CO2. The decrease in reaction rate was mainly ascribed to the formation of carbamate from benzylamine and the intermediate 1-aminodibenzylamine reacting with CO2, and it precipitated out to coat on the surface of catalyst in solventless and hexane, and the dilution effect of compressed CO2 in ethanol. But the yield of benzylamine was increased in solventless, hexane and ethanol due to the following nucleophilic addition of benzylamine and benzylimine to N-benzylidenebenzylamine was inhibited. Although, the reaction rate increased in water for the enhanced solubility of H2 and benzonitrile in H2O and decreased mass-transfer resistance in the presence of compressed CO2, the yield of benzylamine decreased because of the acidic nature of H2O-CO 2 favorites the elimination of NH3 and the formation of NH4HCO3. Accordingly, the possible reaction pathway of benzonitrile hydrogenation was proposed for all the studied systems. © 2013 Elsevier B.V. All rights reserved.

Abstract  The most significant modulators of the cyanotoxins microcystin and β-N-methylamino-L-alanine in laboratory cyanobacterial cultures are the concentration of growth-medium combined nitrogen and nitrogen uptake rate. The lack of field studies that support these observations led us to investigate the cellular content of these cyanotoxins in cyanobacterial bloom material isolated from a freshwater impoundment and to compare these to the combined nitrogen availability. We established that these toxins typically occur in an inverse relationship in nature and that their presence is mainly dependent on the environmental combined nitrogen concentration, with cellular microcystin present at exogenous combined nitrogen concentrations of 29 μM and higher and cellular BMAA correlating negatively with exogenous nitrogen at concentrations below 40 μM. Furthermore, opposing nutrient and light gradients that form in dense cyanobacterial blooms may result in both microcystin and BMAA being present at a single sampling site.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. An amperometric biosensor for the detection of organophosphate and carbamate pesticides was constructed as a disposable strip containing a cobalt phthalocyanine-modified carbon composite electrode and a cross-linked cholinesterase layer. With butyrylthiocholine as substrate, enzymatically produced thiocholine was oxidized at +250 mV. The steady-state current, Iss, was used as a measure of the enzyme activity. In the presence of pesticides, an irreversible inhibition of cholinesterase occurred, resulting in a decrease in the rate of current change, dI/dt. The ratio (dI/dt)ss was used for evaluations. The influence of the cholinesterase loading and the cholinesterase to glutaraldehyde ratio on the biosensor response was studied and the measuring conditions (pH, temperature, substrate concentration) were optimized. Detection limits of 0.30, 1.2 and 11 nmol l-1 for paraoxon, dichlorvos and carbaryl, respectively, were achieved. The time of inhibition varied from a few second

Abstract  Aqueous solutions of diethyl phthalate (DEP) were oxidized by using ozone combined with Fenton reagents. The effects of operating parameters such as initial pH; initial concentration of DEP, H2O2 and Fe(2+); [H2O2]0/[Fe(2+)]0 ratio and O3 dosage on the degradation rates of DEP were investigated. The results showed that DEP degradation is strongly dependant on the pH; initial concentrations of the phthalate, H2O2 and Fe(2+); [H2O2]0/[Fe(2+)]0 ratio and O3 dosage. The addition of H2O2 and Fe(2+) ions was effective to achieve almost 98% degradation of 200 mg L(-1) of DEP in about 40 min using a dose of O3 = 45 g m(-3) NTP; [H2O2]0 = 2.5 × 10(-2) mol L(-1) and [Fe(II)]0 = 5 × 10(-3) mol L(-1), as compared to over 60 min by using O3 and Fenton processes applied separately. DEP degradation followed apparent pseudo-first-order kinetics under ozonation, Fenton's reagents oxidation and the combined ozonation/Fenton reagents oxidation process. The overall reaction rates were significantly enhanced in the O3/Fe(2+)/H2O2 oxidation system, and allows achieving 100% degradation of DEP (100 mg L(-1)) in 30 min of reaction time. The notable decrease in DEP removal rate observed in the presence of a radical scavenger indicates that there was an obvious synergetic effect in the combined ozonation/Fenton reagent process most likely because ozonation could accelerate Fenton reagents to generate hydroxyl radical HO•. Thus, the reaction between DEP and HO• proceeds mainly in the bulk of the aqueous phase. Under optimal conditions, the O3/Fe(2+)/H2O2 system oxidation was the most effective in DEP removal in water.

Abstract  The emergence of diseases and mortalities in aquaculture and development of antibiotics resistance in aquatic microbes, has renewed a great interest towards alternative methods of prevention and control of diseases. Nanoparticles have enormous potential in controlling human and animal pathogens and have scope of application in aquaculture. The present investigation was carried out to find out suitable nanoparticles having antimicrobial effect against aquatic microbes. Different commercial as well as laboratory synthesized metal and metal oxide nanoparticles were screened for their antimicrobial activities against a wide range of bacterial and fungal agents including certain freshwater cyanobacteria. Among different nanoparticles, synthesized copper oxide (CuO), zinc oxide (ZnO), silver (Ag) and silver doped titanium dioxide (Ag-TiO2) showed broad spectrum antibacterial activity. On the contrary, nanoparticles like Zn and ZnO showed antifungal activity against fungi like Penicillium and Mucor species. Since CuO, ZnO and Ag nanoparticles showed higher antimicrobial activity, they may be explored for aquaculture use.