Toxicological Events Research Articles

Systematic analysis of silver nanoparticle ionic dissolution by tangential flow filtration: toxicological implications

In the field of toxicology of nanomaterials, scientists have not clearly determined if the observed toxicological events are due to the nanoparticles (NPs) themselves or the dissolution of ions released into the biophysiological environment or both phenomenon participate in combination based upon their bioregional and temporal occurrence during exposure conditions. Consequently, research involving the toxicological analysis of silver NPs (Ag-NPs) has shifted towards assessment of ‘nanosized' silver in comparison to its solvated ‘ionic' counterpart. Current literature suggests that dissolution of ions from Ag-NPs may play a key role in toxicity; however, the present assessment methodology to separate ions from NPs still requires improvement before a definitive cause of toxicity can be determined. Recently, centrifugation-based techniques have been employed to obtain solvated ions from the NP solution, but this approach leads to NP agglomeration, making further toxicological analysis difficult to assess. Additionally, extremely small NPs are retained in the supernatant even after ultracentrifugation, leading to incomplete separation of ions from their respective NPs. To address these complex toxicology issues we applied enhanced separation techniques with the aim to study levels of ions originating from the Ag-NP using separation by a recirculating tangential flow filtration system. This system uses a unique diffusion-driven filtration method that retains large particles within the continuous flow path, while allowing the solution (ions) to pass through molecular filters by lateral diffusion separation. Use of this technique provides reproducible NP separation from their solvated ions which permits for further quantification using an inductively coupled plasma mass spectrometry or comparison use in bioassay exposures to biological systems. In this study, we thoroughly characterised NPs in biologically relevant solutions to understand the dissolution of Ag-NPs (10 and 50 nm) over time. Our results suggest that the ion dissolution from Ag-NPs is dependent on parameters such as exposure time, chemical composition and temperature of the exposure solution. Further, the well-characterised separated ionic and NP solutions were exposed to a lung epithelial cell line (A549) to evaluate the toxicity of each fraction. Results suggest that although Ag-NPs (unseparated) show concentration-dependent toxicity, dissolution of ions appears to exacerbate the toxicological effect. This finding adds data to the set of probable toxic exposure mechanisms elicited by metallic nanomaterials and provides important consideration when assessing findings of key cell function modulation.

In Situ Mass Spectrometry Imaging and Ex Vivo Characterization of Renal Crystalline Deposits Induced in Multiple Preclinical Drug Toxicology Studies

Drug toxicity observed in animal studies during drug development accounts for the discontinuation of many drug candidates, with the kidney being a major site of tissue damage. Extensive investigations are often required to reveal the mechanisms underlying such toxicological events and in the case of crystalline deposits the chemical composition can be problematic to determine. In the present study, we have used mass spectrometry imaging combined with a set of advanced analytical techniques to characterize such crystalline deposits in situ. Two potential microsomal prostaglandin E synthase 1 inhibitors, with similar chemical structure, were administered to rats over a seven day period. This resulted in kidney damage with marked tubular degeneration/regeneration and crystal deposits within the tissue that was detected by histopathology. Results from direct tissue section analysis by matrix-assisted laser desorption ionization mass spectrometry imaging were combined with data obtained following manual crystal dissection analyzed by liquid chromatography mass spectrometry and nuclear magnetic resonance spectroscopy. The chemical composition of the crystal deposits was successfully identified as a common metabolite, bisulphonamide, of the two drug candidates. In addition, an un-targeted analysis revealed molecular changes in the kidney that were specifically associated with the area of the tissue defined as pathologically damaged. In the presented study, we show the usefulness of combining mass spectrometry imaging with an array of powerful analytical tools to solve complex toxicological problems occurring during drug development.

Real-time monitoring of water quality using fish and crayfish as bio-indicators: a review

Water quality monitoring using fish and crayfish as bio-indicators requires an understanding of the state of pollution of waters, choice of bio-indicators, physiological and behavioral endpoints of fish and crayfish, and principles of the methodology and their potential applications. Here, we discuss telemetry, acoustic monitoring, vision-based monitoring, measures of ventilatory activity, electrocardiography, and fiber-optic plethysmography. Assessment of water quality must be based, not only on physicochemical characteristics of the current environment as determined by chemical analyses, but also on observations of the physiology and behavior of its inhabitants. Real-time biomonitoring is suggested as the most reliable method, since it incorporates living organisms into the system to serve as biosensors. The potential application of the methods discussed includes use at water treatment plants and water supply stations for prevention of hazardous toxicological events, and, for aquaculture, in ponds, lakes, and aquariums for monitoring growth, population size, and behavior traits.

Characterization of Differential Cocaine Metabolism in Mouse and Rat through Metabolomics-Guided Metabolite Profiling

Rodent animal models have been widely used for studying neurologic and toxicological events associated with cocaine abuse. It is known that the mouse is more susceptible to cocaine-induced hepatotoxicity (CIH) than the rat. However, the causes behind this species-dependent sensitivity to cocaine have not been elucidated. In this study, cocaine metabolism in the mouse and rat was characterized through LC-MS-based metabolomic analysis of urine samples and were further compared through calculating the relative abundance of individual cocaine metabolites. The results showed that the levels of benzoylecgonine, a major cocaine metabolite from ester hydrolysis, were comparable in the urine from the mice and rats treated with the same dose of cocaine. However, the levels of the cocaine metabolites from oxidative metabolism, such as N-hydroxybenzoylnorecgonine and hydroxybenzoylecgonine, differed dramatically between the two species, indicating species-dependent cocaine metabolism. Subsequent structural analysis through accurate mass analysis and LC-MS/MS fragmentation revealed that N-oxidation reactions, including N-demethylation and N-hydroxylation, are preferred metabolic routes in the mouse, while extensive aryl hydroxylation reactions occur in the rat. Through stable isotope tracing and in vitro enzyme reactions, a mouse-specific α-glucoside of N-hydroxybenzoylnorecgonine and a group of aryl hydroxy glucuronides high in the rat were identified and structurally elucidated. The differences in the in vivo oxidative metabolism of cocaine between the two rodent species were confirmed by the in vitro microsomal incubations. Chemical inhibition of P450 enzymes further revealed that different P450-mediated oxidative reactions in the ecgonine and benzoic acid moieties of cocaine contribute to the species-dependent biotransformation of cocaine.

<b>Informação e comunicação em redes de prática como educação permanente: o caso da Estação Escola GHC do Observatório de Tecnologias de Informação e Comunicação em Sistemas e Serviços de Saúde</b>

The complexity of demands in the healthcare field requires greater plasticity in management actions involving multifaceted and trans-disciplinary approaches. The creation of spaces promoting the development and analysis of healthcare information constitutes an innovation strategy, especially when promoting the systematization of knowledge in everyday life. National policy concerning health information enabled the emergence of the OTICS - Observatory of Information Technology and Communication in Health Services and Systems (Observatorio de Tecnologias de Informacao e Comunicacao em Sistemas e Servicos de Saude - OTICS) project. The focus of OTICS lies in supporting new forms of healthcare management by using information to strengthen healthcare practice. The Conceicao Hospital Group School Station (CHG-SS) [Estacao Escola Grupo Hospitalar Conceicao (EE-GHC)] was created within the scope of the OTICS project. This paper aimed to analytically describe an experiment performed in partnership with OTICS and the CHG [GHC] School. First, a conceptual approach was used to address the challenges of performing in highly complex, specialized scenarios, and the potential innovations of using information and associated technologies in everyday health work and management. Two different experiences were analyzed regarding the potential use of information in health surveillance technology development, focusing on the concept of holistic health: the creation of a program for health education and promotion related to toxicological events in children (PEPSET) and another based on the construction of a monitoring and tracking system for orthopedic prosthetics. Regarding PEPSET, multifocal action was taken by training community health agents and other healthcare professionals. As a result, ANVISA (National Agency of Health Surveillance) [Agencia Nacional de Vigilância Sanitaria] approved the methodology, making it viable for disseminating the experiment in other locations and supporting the evaluation mechanism of actions that are still under development. Since its implementation, CHG-SS [EE-GHC] has managed not only to increase the use of information for the qualification of hospital services but also to create a space for the development and analysis of projects. In doing so, it has contributed robust data destined to improve the performance and management of health surveillance within an inter-institutional network and directed toward quality in individual and collective care. In this case, integration is strengthened by inter-institutional articulation with the formation of closer structural and practical bonds between health surveillance and assistance, with the production of useful knowledge for everyday work and prospection in health surveillance. Above all, this takes place by strengthening the role that permanent education plays in healthcare.

Biological effects of palytoxin-like compounds from Ostreopsis cf. ovata: A multibiomarkers approach with mussels Mytilus galloprovincialis

Massive blooms of the harmful benthic dinoflagellate Ostreopsis cf. ovata are of growing environmental concern in the Mediterranean, having recently caused adverse effects on benthic invertebrates and also some intoxication episodes to humans.The toxicological potential of produced palytoxin-like compounds was investigated in the present study on a typical marine sentinel species, the mussel Mytilus galloprovincialis. Organisms were sampled during various phases of a O. cf. ovata bloom, in two differently impacted sites. The presence of the algal toxins was indirectly assessed in mussels tissues (mouse test and hemolysis neutralization assay), while biological and toxicological effects were evaluated through the measurement of osmoregulatory and neurotoxic alterations (Na+/K+-ATPase and acetylcholinesterase activities), oxidative stress responses (antioxidant defences and total oxyradical scavenging capacity), lipid peroxidation processes (level of malondialdehyde), peroxisomal proliferation, organelle dysfunctions (lysosomal membrane stability, accumulation of lipofuscin and neutral lipids), immunological impairment (granulocytes percentage).Obtained results demonstrated a significant accumulation of algal toxins in mussels exposed to O. cf. ovata. These organisms exhibited a marked inhibition of the Na+/K+-ATPase activity and alterations of immunological, lysosomal and neurotoxic responses. Markers of oxidative stress showed more limited variations suggesting that toxicity of the O. cf. ovata toxins is not primarily mediated by an over production of reactive oxygen species. This study provided preliminary results on the usefulness of a multi-biomarker approach to assess biological alterations and toxicological events associated to blooms of O. cf. ovata in marine organisms.

Microarray genomic profile of mitochondrial and oxidant response in manganese chloride treated PC12 cells

Environmental or occupational exposure to high levels of manganese (Mn) can lead to manganism, a symptomatic neuro-degenerative disorder similar to idiopathic Parkinson's disease. The underlying mechanism of Mn neurotoxicity remains unclear. In this study, we evaluate the primary toxicological events associated with MnCl2 toxicity in rat PC12 cells using whole genome cDNA microarray, RT-PCR, Western blot and functional studies. The results show that a sub-lethal dose range (38–300μM MnCl2) initiated slight metabolic stress evidenced by heightened glycolytic rate and induction of enolase/aldolase – gene expression. The largest shift observed in the transcriptome was MnCl2 induction of heme-oxygenase 1 (HO-1) [7.7 fold, p<0.001], which was further corroborated by RT-PCR and Western blot studies. Concentrations in excess of 300μM corresponded to dose dependent loss of cell viability which was associated with enhanced production of H2O2 concomitant to elevation of gene expression for diverse antioxidant enzymes; biliverdin reductase, arsenite inducible RNA associated protein, dithiolethione-inducible gene-1 (DIG-1) and thioredoxin reductase 1. Moreover, Mn initiated significant reduction of gene expression of mitochondrial glutaryl-coenzyme A dehydrogenase (GCDH), an enzyme involved with glutaric acidemia, oxidative stress, lipid peroxidation and striatal degeneration observed in association with severe dystonic-dyskinetic movement disorder. Future research will be required to elucidate a defined role for HO-1 and GCDH in Mn toxicity.

Zebrafish neurotransmitter systems as potential pharmacological and toxicological targets

Recent advances in neurobiology have emphasized the study of brain structure and function and its association with numerous pathological and toxicological events. Neurotransmitters are substances that relay, amplify, and modulate electrical signals between neurons and other cells. Neurotransmitter signaling mediates rapid intercellular communication by interacting with cell surface receptors, activating second messenger systems and regulating the activity of ion channels. Changes in the functional balance of neurotransmitters have been implicated in the failure of central nervous system function. In addition, abnormalities in neurotransmitter production or functioning can be induced by several toxicological compounds, many of which are found in the environment. The zebrafish has been increasingly used as an animal model for biomedical research, primarily due to its genetic tractability and ease of maintenance. These features make this species a versatile tool for pre-clinical drug discovery and toxicological investigations. Here, we present a review regarding the role of different excitatory and inhibitory neurotransmitter systems in zebrafish, such as dopaminergic, serotoninergic, cholinergic, purinergic, histaminergic, nitrergic, glutamatergic, glycinergic, and GABAergic systems, and emphasizing their features as pharmacological and toxicological targets. The increase in the global knowledge of neurotransmitter systems in zebrafish and the elucidation of their pharmacological and toxicological aspects may lead to new strategies and appropriate research priorities to offer insights for biomedical and environmental research.

A History of Space Toxicology Mishaps: Lessons Learned and Risk Management

After several decades of human spaceflight, the community of space-faring nations has accumulated a diverse and sometimes harrowing history of toxicological events that have plagued human space endeavors almost from the very beginning. Lessons have been learned in ground-based test beds and others were discovered the hard way - when human lives were at stake in space. From such lessons one can build a risk-management framework for toxicological events to minimize the probability of a harmful exposure, while recognizing that we cannot foresee all events. Space toxicologists have learned that relatively harmless compounds can be converted by air revitalization systems into compounds that cause serious harm to the crew. Our toxic risk management strategy now includes an assessment of the fate of any compound that might be released into the atmosphere. Propellants are highly toxic compounds, yet we have not always been able to thoroughly isolate the crew from exposure to these toxicants. Leakage of fluids from systems has resulted in hazardous conditions at times, and the behavior of such compounds inside a spacecraft has taught us how to manage potentially harmful escapes should they occur. Potential combustion events are an ever-present threat to the wellbeing of the crew. Such events have been sufficiently common that we have learned that one cannot judge the health threat of a given fire by the magnitude of the event. Management of such risks demands monitoring of combustion products. In the category of unpredictable toxic events, if one assumes that fires are predictable, we can place experience with toxic microbial metabolites, upsets during repair operations, and discharges from filters that have accumulated a substantial load of pollutants in their absorption beds. Management of such events requires a broad-spectrum, real-time analytical capability to discern the identity and concentrations of pollutants if they enter the atmosphere. Adverse events are an integral part of any human activity, and the spacefaring community must learn as much as possible from mistakes and near misses.

Prediction of toxicology and pharmacology based on model toxicophores and pharmacophores using the new TOX-MATCH-PHARM-MATCH program

A unique computer program TOX-MATCH–PHARM-MATCH enables prediction of toxicology or pharmacology based on a reverse search strategy. It is logistically unfeasible to break each of the 5.5-6 million unique compounds indexed by Chemical Abstracts into all possible substructural fragments and then to try to match these to a list of substructural fragments known to cause certain toxicological or pharmacological effects. Rather, our program has a library of model chemical structural toxicophores or pharmacophores in a tree structure using our special chemical coding method (based on topology, topography, graph theory, and some special theories). This library is then followed by a library of the toxicological or pharmacological triggering events (ttes or ptes) (usually biochemical) caused by each model toxicophore or pharmacophore, the subsequent physiological events (spes) (also usually biochemical) and the observed physiological signs and symptoms (opsss) of each species. An unknown sample is input (also in the special chemical coding), and the model toxicophore or pharmacophore queries the sample compound to see how close the match is (hence, the reverse search strategy). Then, the program prints out the matches it finds and at what levels of the tree structure and the ttes or ptes, spes, and the opsss to be expected. The program also has a backtrack capability to trace from opsss back to the ttes or ptes and to the possible model toxicophores or pharmacophores. This program is open ended and extremely versatile and can be used for any toxicological or pharmacological problem.

Atmospheric Distribution of Gas- and Particle-Phase Quinones in Southern California

Quinones are reactive organic compounds known to initiate reactions associated with a host of toxicological events. Their presence in different atmospheres has been demonstrated although their sources remain uncertain. As a result of their reactivity and instability during chemical analysis, only a limited number of studies have reported on atmospheric concentrations of quinones in ambient air. Furthermore, besides the limited information on quinones associated with particulate matter, no previous studies have quantified vapor-phase quinones. We report vapor- and particle-phase concentrations of 1,2- and 1,4-naphthoquinones (1,2-NQ, 1,4-NQ), 9,10-phenanthraquinone (9,10-PQ), and 9,10-anthraquinone (9,10-AQ), measured over a 5-year period in Southern California. The results showed that vapor-phase concentrations of the target quinones were in general higher than those in the particle-phase. Vapor-phase concentrations ranged from 80 pg/m 3 for the AQ to 1747 pg/m 3 for the 1,4-NQ, and the particle-phase con...

Biomarkers For Environmental Monitoring

Many researches about toxicology, especially aquatic toxicology, have focused extensively on the early phases of the impact of a contaminant with an organism, characterized by its interaction with the endogenous molecules. Fig. 1 reports a synthesis of the interactions between the contaminants present in the aquatic ecosystem and their biological effects. Toxicology evaluations do not have recourse to biological indicators in the strict sense of the term. In the field of toxicology, there are very interesting prospects for biomarkers, which are specific biochemical, genetic, morphological or physiological changes measurable in each organism and which are associated with particular stress situations (for instance, in the presence of heavy metals, pesticides, etc.). Biomarkers signal the occurrence of toxicological events much earlier than the emergence of those effects that can be measured in biocoenosis at the population level. The measurements of the biological effect ensuing exposure to contaminants follow two main criteria [1–4]:

Lessons Learned from Chlorine Intoxications in Swimming Pools: The Challenge of Pediatric Mass Toxicological Events

The classical doctrine of mass toxicological events provides general guidelines for the management of a wide range of "chemical" events. The guidelines include provisions for the: (1) protection of medical staff with personal protective equipment; (2) simple triage of casualties; (3) airway protection and early intubation; (4) undressing and decontamination at the hospital gates; and (5) medical treatment with antidotes, as necessary. A number of toxicological incidents in Israel during the summer of 2005 involved chlorine exposure in swimming pools. In the largest event, 40 children were affected. This study analyzes its medical management, in view of the Israeli Guidelines for Mass Toxicological Events. Data were collected from debriefings by the Israeli Home Front Command, emergency medical services (EMS), participating hospitals, and hospital chart reviews. The timetable of the event, the number and severity of casualties evacuated to each hospital, and the major medical and logistical problems encountered were analyzed according to the recently described methodology of Disastrous Incident Systematic Analysis Through-Components, Interactions, Results (DISAST-CIR). The first ambulance arrived on-scene seven minutes after the first call. Emergency medical services personnel provided supplemental oxygen to the victims at the scene and en route when required. Forty casualties were evacuated to four nearby hospitals. Emergency medical services classified 26 patients as mildly injured, 13 as mild-moderate, and one as moderate, suffering from pulmonary edema. Most children received bronchodilators and steroids in the emergency room; 20 were hospitalized. All were treated in pediatric emergency rooms. None of the hospitals deployed their decontamination sites. Event management differed from the standard Israeli toxicological doctrine. It involved EMS triage of casualties to a number of medical centers, treatment in pediatric emergency departments, lack of use of protective gear, and omission of decontamination prior to emergency department entrance. Guidelines for mass toxicological events must be tailored to unique scenarios, such as chlorine intoxications at swimming pools, and for specific patient populations, such as children. All adult emergency departments always should be prepared and equipped for taking care of pediatric patients.

Induction of Rat Hepatic Cytochrome P-450 by Ketamine and its Toxicological Implications

Ketamine is a common intravenous anesthetic and a frequent drug of abuse, alone or in combination with cocaine. However, the pharmacokinetic effects of ketamine have not been fully investigated. This study determined the effects of ketamine on cytochrome P-450 (P-450)-dependent catalytic activities, protein levels, and hepatotoxicity using male Wistar rats treated with 10, 20, 40, or 80 mg/kg ketamine intraperitoneally twice daily for 4 d. Treatment with ketamine produced a dose-dependent increase of pentoxyresorufin O-dealkylation activity of liver microsomes. Treatment with 80 mg/kg ketamine resulted in 14-, 3-, and 2-fold rise in O-dealkylation of pentoxyresorufin, ethoxyresorufin, and methoxyresorufin of rat liver microsomes, respectively. The treatment produced 31% and 86% increases in 7-ethoxycoumarin O-deethylation and erythromycin N-demethylation, respectively. In addition, aniline hydroxylation activity was elevated by 62%. Protein blot analysis of liver microsomal proteins revealed that 80 mg/kg ketamine induced P-450 1A, 2B, 2E1, and 3A proteins by 2-, 13-, 2-, and 2-fold, respectively. In reversibility study, ketamine-induced pentoxyresorufin O-dealkylation, 7-ethoxycoumarin O-deethylation, erythromycin N-demethylation, and methoxyresorufin O-demethylation activities of liver microsomes prepared from rats 4 d after ketamine treatment were 75%, 48%, 29%, and 38% lower than the respective activities of liver microsomes prepared from rats 1 d after treatment. Protein blot analysis showed that ketamine-induced P-450 2B1/2 proteins also decreased in a time-dependent manner in 4 d. In hepatotoxicity study, treatment of rats with 1 ml/kg CCl4 produced a 7-fold increase in serum alanine aminotransferase activity level and a 17-fold rise in rats pretreated with 80 mg/kg ketamine for 4 d. Treatment of ICR mice with 120 mg/kg cocaine produced a 17% mortality, whereas the same dose of cocaine produced a 50% mortality in mice pretreated with ketamine. Treatment of mice with 100 mg/kg cocaine produced a 76-fold increase in serum alanine aminotransferase activity level and a 260-fold rise in mice pretreated with 80 mg/kg ketamine for 4 d. The present study shows that ketamine induces the expression of multiple forms of P-450 in rat liver microsomes and increases CCl4-induced liver toxicity and cocaine-mediated acute toxicity. Other potential pharmacological or toxicological events related to ketamine use need to be further explored.

Determination of Four Quinones in Diesel Exhaust Particles, SRM 1649a, and Atmospheric PM2.5Special Issue ofAerosol Science and Technologyon Findings from the Fine Particulate Matter Supersites Program

Quinones are reactive organic compounds and are known to initiate reactions associated with many toxicological events. Their presence in air pollution has been demonstrated, but routine quantitative measurements are lacking. A quantitative method for the determination of four quinones was developed using diesel exhaust particles (DEP) and National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1649a. The method was then used to analyze ambient air samples from different sites in Southern California. After extraction in dichloromethane, the target compounds were converted to their stable diacetyl derivatives and determined by electron impact GC-MS using selected ion monitoring. Calibration plots were obtained with deuterium-labeled internal standards. The four quinones, 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), 9,10-phenanthraquinone (9,10-PQ), and 9,10-anthraquinone (9,10-AQ), were quantified in DEP, in SRM 1649a, and in ambient air samples of PM2.5 collecte...

Evaluation of the genotoxicity induced by the fungicide fenarimol in mammalian and plant cells by use of the single-cell gel electrophoresis assay

Fenarimol, a systemic pyrimidine carbinol fungicide, is considered to be not genotoxic or weakly genotoxic, although the available toxicological data are controversial and incomplete. Our results obtained in vitro with leukocytes of two different rodent species (rat and mouse) show that fenarimol affects DNA, as detected by the single-cell gel electrophoresis (SCGE, Comet) assay. This fungicide is able to induce DNA damage in a dose-related manner, with significant effectiveness at 36 nM, but without significant interspecies differences. Simultaneous exposure of rat leukocytes to fenarimol (36–290 nM) and a model genotoxic compound (50 μg/ml bleomycin) produced a supra-additive cytotoxic and genotoxic effect. This supports previous findings suggesting possible co-toxic, co-mutagenic, cancer-promoting and co-carcinogenic potential of fenarimol, and modification of the effects of other xenobiotics found to be influenced by this agrotoxic chemical, with consequent different toxicological events. The potential for DNA strand breaks to act as a biomarker of genetic toxicity in plants in vivo was also considered, in view of the fact that higher plants represent reliable sensors in an ecosystem. Significant DNA breakage was observed in the nuclei of Impatiens balsamina leaves after in vivo treatment with fenarimol (145 nM, 1 h). More than 50% of the cells showed such DNA damage.

Iron release, oxidative stress and erythrocyte ageing

Iron, to be redox cycling active, has to be released from its macromolecular complexes (ferritin, transferrin, hemoproteins, etc.). Iron is released from hemoglobin or its derivatives in a nonprotein-bound, desferrioxamine-chelatable form (DCI) in a number of conditions in which the erythrocytes are subjected to oxidative stress. Such conditions can be related to toxicological events (haemolytic drugs) or to physiological situations (erythrocyte ageing, reproduced in a model of prolonged aerobic incubation), but can also result from more subtle circumstances in which a state of ischemia-reperfusion is imposed on erythrocytes (e.g., childbirth). The released iron could play a central role in oxidation of membrane proteins and senescent cell antigen (SCA) formation, one of the major pathways for erythrocyte removal. Iron chelators able to enter cells (such as ferrozine, quercetin, and fluor-benzoil-pyridoxal hydrazone) prevent both membrane protein oxidation and SCA formation. The increased release of iron observed in β-thalassemia patients and newborns (particularly premature babies) suggests that fetal hemoglobin is more prone to release iron than adult hemoglobin. In newborns the release of iron in erythrocytes is correlated with plasma nonprotein-bound iron and may contribute to its appearance.

High-performance liquid chromatographic method for therapeutic drug monitoring of cyclosporine A and its two metabolites in renal transplant patients

A novel fast HPLC method was developed for the determination of cyclosporine A (CyA) and its two metabolites M17 (AM1) and M21 (AM4N) in blood. Whole blood was precipitated with zinc sulphate, extracted with diethyl ether, evaporated, dissolved in aqueous methanol and partitioned twice with n-hexane. Chromatography was carried out using a microbore RP-column under isocratic elution with acetonitrile–methanol–water (200:80:140, v/v/v) at 70°C and a detector set at 205 nm. Linearity for all three compounds was tested in the range of 1–1000 ng/ml. Recovery was 97–109%, and a coefficient of variation was 1.6–8.8% depending on the particular compound and its concentration. The method was used for a group of renal transplant patients having an inadequate response to CyA therapy in order to evaluate the possible role of CyA and its metabolites on the occurrence of hypertension and other toxicological events.

Development of a Cell Culture Model System for Routine Testing of Substances Inducing Oxidative Stress

The toxicological model of oxidative stress is a mechanism which is currently thought to be involved in the formation and development of many serious human diseases. Little is known about cellular responses to oxidative damage and the related specific toxicological properties of substances such as chemicals or components of the polluted urban atmosphere. On the basis of biological pathways involved in cellular antioxidative mechanisms, we developed a biological model for studying the oxidative properties of substances. This includes human lung cells and methods for biochemical analysis of cellular endpoints. Antioxidative and glycolysis-related enzyme activities (glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, phosphofructokinase, enolase, glucose-6-phosphate dehydrogenase), ATP/ADP/AMP and glutathione (oxidized and reduced) are determined. Routine testing of substances with high reproducibility and fast screening is provided by adapting methods for biochemical analysis to determinations using cells grown on microtitre plates. First experiments with standard model substances inducing oxidative stress such as H 2O 2 and tert-butylhydroperoxide show that enzymatic activities can be measured with good reproducibility and their changes can be followed kinetically. The results indicate the relevance of the determined parameters for such toxicological events and the usefulness of the biological indicator system for routine testing.

Preparing hospitals for toxicological mass casualties events.

For most hospital staffs, treatment of chemical casualties presents an obscure and even frightening situation. We report our unique experience from hospital drills in order to improve hospital preparedness for patient management under mass casualty conditions involving hazardous chemicals. Twenty-one major hospitals in Israel. A unique hospital deployment plan for the management of chemical casualties was developed, and hospitals were required to have a full chemical practice drill every 3 to 5 yrs. These drills were designed as realistically as possible, and all included the use of personal protective equipment, decontamination, and treatment of simulated patients. Twenty-five percent of these patients, simulating children and adults, required intensive care and ventilation support. Hospitals were inspected and reviewed on the quality of treatment given and the overall continuity of care as well as on their administrative performance. Between 1986 to 1994, 30 full chemical practice drills were conducted in 21 major hospitals. Each drill included treatment of 100 to 400 simulated patients. The lessons from the hospital drills are described and were incorporated in the proposed revised hospital deployment plan. All hospitals significantly improved their ability to respond appropriately to these incidents. The level of preparedness for a chemical mass casualty scenario should be established according to the existing threat and the available resources. The proposed plan can serve as a basis for hospital planning and staff training worldwide, thus facilitating optimal care in the event of an incident involving toxic chemicals. A cost-effective scale for hospital preparation levels according to the existing threat is suggested.