Ingestion Of Toxins Research Articles

Envenenamiento por Paraquat y hemoperfusión con carbón activado

Paraquat is a common herbicide in Spain. In our country there are a few cases of this intoxication and it presents a high mortality even if the patients ingest a minimal amount. We present two cases of accidental poisoning with paraquat. These patients were admitted three hours after ingestion of toxin. They were treated with with orogastric lavage, activated charcoal, N-acetylcysteine, Fuller's earth, cathartics, support measures and hemoperfusion with activated charcoal. With these treatments both patients had a undetectable levels of paraquat 48 hours after and improvement of their symptoms, gastric and intestinal predominantly . We present the graphics of evolution of the plasma and urine levels of paraquat in both patients. We review the different aspects of treatment and update of this poisoning.

Detecting organic toxins in possible fatal poisonings – a diagnostic problem

Two fatal cases are reported where there was strong circumstantial evidence of plant toxin ingestion. In only one case however was a low urine level of hyoscine detected (in keeping with a history of Datura sp. consumption). Fatal cases of plant toxin ingestion may be a problem for the laboratory given the wide range and rarity of certain plant poisons, and the limitation of standard screening. Identification of plant materials at the scene of suspected poisoning may be crucial in directing toxicological investigations.

Behavioral responses to plant toxins by two omnivorous lizard species

An ability to detect plant toxins and thereby avoid eating chemically defended plants would be very beneficial for omnivorous and herbivorous lizards. We studied the ability of the omnivorous Podarcis lilfordi to detect compounds belonging to three classes of common plant toxins, as well as responses indicating aversion. Solutions of the alkaloid quinine, saponin, and the phenolic coumarin, as well as distilled water (odorless control), were presented to lizards on cotton swabs. The lizards detected all three toxins as indicated by significantly decreased tongue-flick rates and tongue-flick attack scores in comparison with distilled water. Several other variables revealed aversion to saponin, including a low number of individuals that bit swabs, avoidance of swabs after tongue-flicking, performance after tongue-flicking the swab of repeated short-excursion tongue-flicks that were directed away from the swab and did not contact any substrate, failure to respond at all in the next trial, and wiping the snout on the floor of the terrarium. Reasons for apparent differences in tongue-flicking behavior between P. lilfordi and two other omnivorous lizard species are discussed. We also showed experimentally that saponin depresses the tongue-flick rate in the omnivorous Bonaire whiptail lizard, Cnemidophorus murinus. Tongue-flicking enables at least one lizard species to detect specific chemicals representing three major classes of plant toxins. It is hypothesized that this ability is a widespread adaptation to reduce ingestion of plant toxins.

Hallazgos mediante resonancia magnética en un paciente con anosmia no postraumática

The presence of alterations in the neuroimaging in patients with anosmia without traumatic antecedents is not frequent. Male aged 38 who came to surgery after having suffered, 6 months earlier, for 1 week, a picture of intense, oppressive holocranial headache, accompanied by fever. Associated with this, an acute complete anosmia also began and persisted up to the moment the patient came for consultation. It was not associated with any infection of the respiratory tract, there was no history of cranial trauma, no ingestion of medicines nor toxins, nor had he been exposed to toxic products. The exploration to which he was submitted only showed an anosmia and was otherwise found to be normal. Cranial MRI showed signal alterations in both lower (orbitary) convolutions of the frontal lobes, in the anterior region of the right temporal lobe and in both olfactory nerves. Tests for HIV serology, parotiditis, hepatitis B and C virus, HSV, VZV, Mycoplasma pneumoniae and lues were negative. The acute onset of the anosmia in midst of a picture of febricula and headaches made us suspect the presence of an infectious aetiology, and the alterations found in the neuroimaging could be due to post encephalic lesions, with a special predilection for olfactory areas. 1. MRI plays a fundamental role in the topographic and aetiological evaluation of olfactory dysfunctions of a central origin; 2. Affectation of the central olfactory passages of an infectious aetiology in a non HIV patient and with neuroimaging findings is a rare complication.

Central neurocircuitry associated with emesis

Ingestion of toxin, traumatic events, adverse drug reactions, and motion can all result in nausea and emesis. In addition, cyclic vomiting syndrome is quite prevalent in the pediatric population. Coordination of the various autonomic changes associated with emesis occurs at the level of the medulla oblongata of the hindbrain. Chemosensitive receptors detect emetic agents in the blood and relay this information by means of neurons in the area postrema to the adjacent nucleus tractus solitarius (NTS). Abdominal vagal afferents that detect intestinal luminal contents and gastric tone also terminate in the NTS (gelatinosus, commissural, and medial subnuclei). The NTS is viscerotopically organized into subnuclei that subserve diverse functions related to swallowing (subnucleus centralis), gastric sensation (subnucleus gelatinosus), laryngeal and pharyngeal sensation (intermediate and interstitial NTS), baroreceptor function (medial NTS), and respiration (ventrolateral NTS). Neurons from the NTS project to a central pattern generator (CPG), which coordinates the sequence of behaviors during emesis, as well as directly to diverse populations of neurons in the ventral medulla and hypothalamus. Thus, it is critical to realize that there is not an isolated “vomiting center,” but rather groups of loosely organized neurons throughout the medulla that may be activated in sequence by a CPG. The newer antiemetic agents appear to block receptors in the peripheral endings of vagal afferents to reduce “perception” of emetic stimuli and/or act in the dorsal vagal complex. A primary site of action of 5-HT 3-receptor antagonists is by means of the vagal afferents. Neurokinin-1 receptor (NK 1R) antagonists are antiemetics, because they act at a site in the dorsal vagal complex. Part of their effectiveness may be the result of inhibition of the NK 1R on vagal motor neurons to prevent fundic relaxation, which is a prodromal event essential for emesis. Delta 9-tetrahydrocannabinol (Δ 9-THC), the major psychoactive component of marijuana, can be therapeutically useful as an antiemetic. The site of action of Δ 9-THC is on cannabinoid CB1 receptors in the dorsal vagal complex. However, it decreases fundic tone and antral motility. It is not easy to predict the potential antiemetic effects of drugs that alter motility. Although antiemetic drugs are available for management of acute chemotherapeutic-induced emesis, few treatments are effective for delayed emesis or cyclic vomiting syndrome.

Acute liver failure.

Acute liver failure (ALF) is defined as hepatic encephalopathy complicating acute liver injury. The most common etiologies are acute viral hepatitis A and B, medication overdose (e.g., acetaminophen), idiosyncratic drug reactions, ingestion of other toxins (e.g., amanita mushroom poisoning), and metabolic disorders (e.g., Reye's syndrome). Despite advances in intensive care management, mortality continues to be high (40-80%) and is partly related to ALF's complications, such as cerebral edema, sepsis, hypoglycemia, gastrointestinal bleeding, and acute renal failure. Several prognostic models have been developed to determine which patients will spontaneously recover. Treatment is directed at early recognition of the complications and general supportive measures. The only proven therapy for those who are unlikely to recover is liver transplantation. Therefore, recognition of ALF is paramount, and urgent referral to a transplant center is critical to assess transplantation status.

Analytical techniques for monitoring harmful cyanobacteria in lakes

The toxins of cyanobacteria include potent neurotoxins and hepatotoxins. Deaths after exposure by ingestion of cyanobacterial cells and toxins from freshwater sources have been reported. The hepatotoxins are cyclic peptides, which comprise microcystins (MC) and nodularin (NOD), and they cause poisonings with an established syndrome of human and animal illnesses. The identification and determination of these hepatotoxic peptides are challenges for analytical chemists. Methods based on solid phase extraction and size exclusion chromatography are available for the clean up of raw extracts. Both principles are also used for the enrichment of MC from low contaminated sample material. The separation of MC is achieved by high-pressure liquid chromatography methods with ultraviolet (UV) detection or mass spectrometric detection. The unambiguous identification of MC not available as standards is possible by mass spectrometry (MS) or, under optimal conditions, by UV spectrometry using diode array detection. To date, 60 different MC and four NOD have been described, but new compounds are frequently identified. Therefore, powerful tools for the elucidation of the structure of unknown MC are an important need. In addition to classical methods for structure elucidation (e.g. nuclear magnetic resonance spectrometry), microwave-assisted hydrolysis of cyclic peptides followed by enantio-selective determination of the amino acid profiles can be used. More recently, MS with collision-activated dissociation has become an important tool for obtaining structure information. The present paper discusses the advantages and disadvantages of the various analytical techniques used for monitoring of cyanobacteria in lakes, optimized or developed at the Institute of Nutrition, Jena, Germany. A pathway for handling MC-containing samples with regard to different analytical tasks (i.e. the identification and elucidation of structure followed by qualitative and quantitative determination) is proposed.

Surtos de botulismo em bovinos no Brasil associados à ingestão de água contaminada

Botulismo em bovinos resulta da ingestão de toxina previamente formada. No presente trabalho são descritos sete surtos da intoxicação onde os dados clínico-patológicos, epidemiológicos e os achados laboratoriais indicaram a possível ingestão da toxina através da água contaminada. O coeficiente médio de mortalidade foi de 20,1%, com letalidade de 99,92%, e morbidade de 31,62%. Dos cerca de 9.000 bovinos envolvidos nos surtos, 2.844 morreram com quadro clínico predominantemente superagudo e agudo. A alta morbidade e mortalidade foram registradas num curto período de tempo e envolveram todas as categorias animais, com quadro clínico-patológico caracterizado por paresia e paralisia da musculatura da locomoção, deglutição e mastigação e ausência de lesões macroscópicas. As circunstâncias em que ocorreram os surtos estiveram relacionadas com a existência de carcaças de animais decompostas ou matéria orgânica vegetal na água de dessedentação. Foram detectadas toxinas botulínicas C e/ou D nas coleções de água, nas vísceras e no soro sangüíneo de parte considerável dos materiais examinados.

Poisoning in Saudi Arabia: Ten-Year Experience in King Khaled University Hospital

The Pharmacy Services Department of King Khalid University Hospital (KKUH) established a poison control service in conjunction with their drug information center in October 1983. The primary goal of the poison information service was to offer expert advice from well-trained clinical pharmacists in the management of poisoning cases throughout the Kingdom of Saudi Arabia. The service was made available 24 hours a day (calls received from 7:30 am to 4:00 pm were managed by the Drug and Poison Information Center [DPIC], while after-hours consultations were managed by on-call clinical pharmacists). Information on poisoning management was targeted towards physicians, even though advice was also available to other paramedical personnel and the lay public. A retrospective study of poisoning cases received between October 1986 and October 1996 was undertaken to ascertain the fulfilment of initial goals, determine areas of weakness, and identify any trends in the poisoning cases received at our center. This was critical to help improve the service and increase physician and pharmacist awareness of poisoning trends. We believe that this is the first practical study to evaluate the pattern of poisoning in the country based on factual data. It was not possible to assess the quality of the services extensively or its impact on outcome, since follow-up information was not available. Patients were admitted for a short period of time, especially those from rural areas. Treating physicians were not available for comments on the follow-up of the patients. Moreover, once the patients move from the Accident and Emergency Department, it becomes difficult to track them. The only exceptions were the critical cases that we were able to follow until either complete recovery or demise.

Foraging strategies and growth inhibition in five daphnids feeding on mixtures of a toxic cyanobacterium and a green alga

1. Laboratory experiments were used to study the feeding, growth and reproduction of five daphnids in mixtures of a toxic cyanobacterium, Microcystis aeruginosa, and a green alga, Scenedesmus acutus. The mixtures included 0%, 20%, 50%, 80% and 100% Microcystis with a total food concentration of 0.5 mg C L−−1 in each treatment. The feeding rate was measured after 1 and 24 h of acclimatization to the mixtures.2. Toxic Microcystis inhibited feeding in all the species, but they exhibited an unexpected diversity and complexity in the pattern of feeding inhibition. Daphnia magna exhibited the strongest inhibition of feeding after 1 h of exposure to toxic food, but had substantially recovered after 24 h in the same mixtures. This pattern of inhibition and recovery may balance the benefits of reduced ingestion of toxin with the disadvantage of a reduced energy intake.3. All five daphnids grew quickly in the Scenedesmus control, whereas growth and reproduction declined with an increasing proportion of the toxic alga in the diet. Daphnia pulicaria showed the least inhibition of growth and reproduction, D. pulex showed the strongest inhibition and the three remaining species exhibited intermediate sensitivity.4. Estimates of gross growth efficiency (GGE; growth/ingestion) provided a means for discriminating between the effects of feeding inhibition and direct toxicity on zooplankton growth. Daphnia pulex exhibited a sharp decline in GGE, suggesting that growth inhibition was a result of both feeding inhibition and direct toxicity. In contrast, D. magna exhibited a nearly constant GGE, indicating that feeding inhibition accounted for its decline in growth. However, two Daphnia species (i.e. D. pulicaria and D. galeata) exhibited improbable increases in GGE with toxic cyanobacteria, suggesting that their feeding rates were underestimated.Growth assays with sensitive and resistant zooplankton species are proposed for testing the potential impacts toxic cyanobacteria in lakes.

Staphylococcal infections in children: part 3.

1. Anjali Jain, MD* 2. Robert S. Daum, MD* 1. 2. *The Department of Pediatrics, Section of Pediatric Infectious Diseases, The University of Chicago, Chicago IL. After completing this article, readers should be able to: 1. Describe the characteristics of toxic shock syndrome in a young child who has multiple organ failure and shock. 2. Plan therapeutic options for children who have community-acquired staphylococcal infections. 3. Describe the clinical features of a food-borne infectious outbreak that suggest the need to include staphylococcal food poisoning in the differential diagnosis. 4. Plan the antimicrobial therapy of staphylococcal infections. ### TOXIC SHOCK SYNDROME In 1978, Todd et al first described toxic shock syndrome (TSS) in seven children. At about the same time, a marked increase in the number of cases called attention to a possible association between TSS and the use of newly introduced superabsorbent tampons by menstruating women. Between 1980 and 1986, 2,960 cases of TSS were reported to the Centers for Disease Control and Prevention (CDC), 90% of which were associated with menses. In 1980, an epidemiologic link between TSS and the use of super-absorbent tampons was discovered; one brand of these tampons was removed from the market in 1980, and all tampons containing poly-acrylate fibers were removed in 1985. Published reports made it apparent that cases of TSS not associated with menses also occurred infrequently among women as well as men and children. Clinically, nonmenstrual and menstrual TSS are similar entities, but they seem to affect different populations and vary in outcome. Since its peak in the early 1980s, the incidence of TSS has decreased markedly with the institution of preventive measures. However, nonmenstrual TSS has decreased to a lesser extent and now accounts for an increased percentage of all TSS cases, currently about 50%. #### Epidemiology Overall, menstrual TSS occurs at an estimated rate of 1 per 100,000 menstruating women per year, 99% of whom use tampons. The decreased incidence of this disease probably is related to a greater awareness of its presentation, the nonuse …

DIAGNOSIS AND MANAGEMENT OF FOOD HYPERSENSITIVITY

Physicians and other healthcare professionals are regularly confronted by patients with numerous signs and symptoms related to the upper and lower respiratory tract, skin, and gastrointestinal tract. After frustration with multiple medication courses or with the patient's or parent's initiative, the question may arise as to whether food allergies are contributing to the problems. Confusion over what constitutes food allergy exists in the medical community as well as in the public. This article clarifies terminology and discusses common presentations, diagnosis, and practical management of food allergy. The term food allergy is often used loosely and incorrectly by physicians, the public, and the media. An accurate general term to describe any abnormal reaction to a food or food additive is adverse food reaction . 14 Adverse food reactions can be the result of food intolerance or food hypersensitivity. 2 Food intolerance accounts for a majority of adverse food reactions and is not immune-mediated. Examples include toxic food poisoning (vomiting and diarrhea from ingestion of staphylococcal or salmonella toxins), pharmacologic effects (jitteriness from caffeine in a cola beverage), and metabolic disorders (bloating and flatus from lactase deficiency). The terms food allergy or food hypersensitivity should be reserved to define an immunologically mediated adverse food reaction. The classic food hypersensitivity reaction is mediated via food-specific IgE-antibodies and, in the most dramatic case, can lead to food-induced anaphylaxis. The other group of food hypersensitivity reactions are non-IgE mediated but involve other immunologic reactions and primarily manifest gastrointestinally. Examples include food-induced enteropathies, such as celiac disease with its characteristic elevated IgA anti-gliadin antibodies. 19

Histopathological Effects and Growth Reduction in a Susceptible and a Resistant Strain of Heliothis virescens (Lepidoptera: Noctuidae) Caused by Sublethal Doses of Pure Cry1A Crystal Proteins from Bacillus thuringiensis

Two strains of the tobacco budworm Heliothis virescens, one selected in the laboratory for resistance to Cry1Ac crystal protein from Bacillus thuringiensis (for which the mechanism of resistance was not associated with reduced binding) and an unselected control strain, were exposed to sublethal doses of pure Cry1A crystal proteins. A histopathological study was conducted to determine the epithelial damage caused by ingestion of Cry1Ac. Tissue sections of the midgut were obtained after 20, 40 and 60 min of toxin ingestion. Histopathological changes were observed primarily in columnar cells and were time-dependent. However, essentially the same level of damage was observed in the two strains. Toxin feeding tests with Cry1Ac and Cry1Ab, indicated that the toxins retarded growth and inhibited food intake of susceptible larvae, but did not significantly affect larvae of the resistant strain. Since the histopathological damage was similar in both strains, it appears that resistant larvae could repair (or substitute) more readily the damaged cells.

Ciguatera (Fish Poisoning), El Niño, and Pacific Sea Surface Temperatures

ABSTRACT Ciguatera (fish poisoning) is the most frequent cause of human illness caused by ingestion of marine toxins. The toxins are ingested by herbivorous fish which feed on marine algae and are then passed up the food chain to humans eating reef fish. We have used a unique database of reported fish poisoning cases in the South Pacific islands to investigate the relationship between fish poisoning and El Niño Southern Oscillation, a periodic disruption of global climate that is associated with marked changes in rainfall, temperatures, and ocean currents. This provides an opportunity to study the effects of a strong climate signal on a sensitive ecosystem in a region that has been less subject to local human disturbance than most others. Using a mixed ecological study design, we calculated correlations between reports of fish poisoning in individual Pacific Islands, estimates of local sea surface temperature, and the Southern Oscillation Index. Strong positive correlations between the annual incidence of fish poisoning and local warming of the sea surface were found in a group of islands which experience warming during El Niño conditions. In another group of islands, which experience cooling of the sea surface during El Niño events, there were weaker negative correlations between fish poisoning and local sea surface temperature. The results are consistent with other evidence suggesting a close interdependence of marine ecosystems and climate. Increases in ciguatera may result if the climate continues to warm as a result of the enhanced greenhouse effect. Coral reefs have been under increasing pressure from human populations in recent years; ciguatera may be a sensitive indicator of environmental disturbance in tropical marine ecosystems.

Role of hemodynamics in pulmonary vascular remodeling: implications for primary pulmonary hypertension.

Primary pulmonary hypertension (PPH) is a disease characterized clinically by the progressive increase in pulmonary artery impedance, which ultimately produces right ventricular failure and death. At the time most patients with PPH present to clinical attention, pathologic lesions include pulmonary artery medial hypertrophy, adventitial thickening, and neointimal lesions. Neointimal lesions are new vascular structures composed of smooth muscle cells (SMC) and extracellular matrix located on the lumenal side of the inner elastic lamina or, if the vessel is too small to have an inner elastic lamina, between the endothelium and the medial layer of the vessel. The terms “neointima” and “neointimal lesions” are used interchangeably in this review. Nearly all active remodeling (as defined by extracellular matrix gene expression) in patients with severe pulmonary hypertension occurs in the neointima (1‐5). This observation underscores the importance of understanding how pulmonary vascular neointimal lesions develop but the pathogenesis and natural history of neointimal lesion formation in PPH are poorly understood. On the basis of animal studies, and by analogy to systemic arterial disease, it seems likely that endothelial injury is required (6). Whether injury occurs secondary to infection (7), ingestion of toxins (8), or activation of autoimmunity (9) remains speculative. Although vascular injury appears necessary to initiate remodeling, other factors besides injury are likely required before pulmonary vascular neointimal lesions develop since the pulmonary artery histology in traditional animal models, in which remodeling is initiated by monocrotaline or hypoxic injury, does not develop lesions that resemble the neointimal lesions of PPH. Hemodynamic forces and injury-induced biochemical mediators are important components in mechanisms of systemic vascular remodeling, including atherosclerosis, restenosis after angioplasty, and neointimal lesions following vascular bypass surgery. New studies suggest hemodynamic factors may be as important in the pulmonary vasculature as they are in the systemic vasculature.

Modifications in dispersal and oviposition of Bt‐resistant and Bt‐susceptible Colorado potato beetles as a result of exposure to Bacillus thuringiensis subsp. tenebrionis Cry3A toxin

AbstractLaboratory strains of Colorado potato beetle, Leptinotarsa decemlineata (Say), physiologically resistant and susceptible to Bacillus thuringiensis (Berliner) subsp. tenebrionis Cry3A toxin were reared to adults on caged potato plants. Influence of three different diets (transgenic potatoes, regular potatoes, and regular potatoes followed by the transgenic potatoes) on beetle mortality, fecundity, and flight behavior were tested under laboratory conditions. A computer‐linked flight mill system was used to quantify beetle flight, and dissections were performed to determine the level of flight muscle development. Susceptible beetles continuously fed on transgenic foliage suffered heavy mortality, did not develop flight muscles, and did not produce any eggs. Resistant beetles continuously fed on transgenic foliage were capable of flight and reproduction; however, it took them longer to initiate flight behavior, and their fecundity was lower than fecundity of other treatments. In both strains, detrimental effects became significantly less severe when the beetles were allowed to feed on regular foliage prior to toxin ingestion. In the resistant strain, ingestion of Cry3A toxin significantly increased flight activity, indicating that physiological resistance was probably reinforced by the behavioral escape from toxic environments. No such response was observed for susceptible beetles. When fed on regular foliage, resistant Colorado potato beetles engaged in significantly fewer flights than susceptible beetles. Behavioral differences between resistant and susceptible beetles observed in the present study are likely to affect gene flow between transgenic crops and adjacent refugia, and should be taken in consideration when designing resistance management plans for transgenic potato crops.

Physiological basis and pharmacology of motion sickness: an update

Motion sickness can occur when sensory inputs regarding body position in space are contradictory or are different from those predicted from experience. Signals from the vestibular system are essential for triggering motion sickness. The evolutionary significance of this malady is unclear, although it may simply represent the aberrant activation of vestibuloautonomic pathways that typically subserve homeostasis. The neural pathways that produce nausea and vomiting during motion sickness are presumed to be similar to those that generate illness after ingestion of toxins. The neural substrate of nausea is unknown but may include neurons in the hypothalamus and inferior frontal gyrus of the cerebral cortex. The principal motor act of vomiting is accomplished through the simultaneous contractions of inspiratory and expiratory respiratory muscles and is mediated by neurons in the lateral medullary reticular formation and perhaps by cells near the medullary midline. Cocontraction of the diaphragm and abdominal muscles increases pressure on the stomach, which causes gastric contents to be ejected through the mouth. Effective drugs for combating motion sickness include antihistamines, antimuscarinics, 5-HT 1A (serotonergic) receptor agonists and neurokinin type 1 receptor antagonists. However, considerable information concerning the physiological basis and pharmacology of motion sickness is unknown; future research using animal models will be required to understand this condition.

Drug-Induced Rhabdomyolysis

The syndrome of rhabdomyolysis is the result of skeletalmuscle injury that alters the integrity of the sarcolemmaand leads to the eventual release of intracellular contentsinto the plasma. The causes are diverse, and includemuscle trauma (for instance, from vigorous exercise, crushinjuries, battering, or seizures), inadequate bloodperfusion, heat stroke, electrolyte imbalance, hereditaryenzyme deficiencies, infections and ingestion of drugs andtoxins. Various serious medical disorders, particularlythose resulting in states of disordered energy production,are also associated with rhabdomyolysis.In general, drug toxicity involves organs, such as thekidney, liver, gastrointestinal tract and the central nervoussystem, with skeletal muscle being usually less readilyaffected. Although drug-induced rhabdomyolysis wasuncommon in the past, it is no longer rare, due to theintroduction of more and increasingly potent drugs intoclinical practice.The incidence of drug-induced rhabdomyolysis isuncertain, largely because most of it is unreported.Similarly, the mortality rates are unknown. However, ithas been suggested that rhabdomyolysis from all causesleads to 5%-25% of cases of acute renal failure.

The pathophysiology of epileptic seizures: a primer for pediatricians.

1. Carl E. Stafstrom, MD, PhD* 1. 2. *Associate Professor of Pediatrics and Neurology, Tufts University School of Medicine; Director, Epilepsy Center for Children, The Floating Hospital for Children at New England Medical Center, Boston, MA. Seizures are one of the most common neurologic disorders affecting children. As many as 5% of children experience a seizure during childhood. Although many epilepsies, especially refractory ones, are managed by specialists in pediatric neurology or epilepsy, general pediatricians often are called upon to manage children who have both acute and chronic seizures. Therefore, it is important to understand some of the basic pathophysiologic mechanisms underlying epileptic seizures. This understanding will allow the physician to choose the most appropriate medication for the given seizure type and clinical setting. Seizures can be a particular challenge to treat. Fortunately, in addition to the armamentarium of anticonvulsant agents previously available, a profusion of new antiepileptic drugs (AEDs) has appeared in the past 5 years. Some of these drugs are designed to address specific pathophysiologic defects in the sequence of events leading to the generation or spread of seizures. The purpose of this article is to review the principles of cellular neurophysiology as a foundation for understanding how normal neuronal function goes awry in epilepsy. First, normal synaptic transmission and neuronal firing are summarized. Next, the pathophysiology of acute and chronic seizures is discussed. Finally, the mechanisms by which AEDs control the hyperexcitability that underlies epilepsy are considered. ### DEFINITIONS A seizure is a temporary disruption of brain function due to the hypersynchronous, excessive discharge of cortical neurons. Sometimes the term epileptic seizure is used to distinguish from a nonepileptic seizure such as a pseudoseizure, which is not caused by hypersynchronous firing of neurons. The clinical manifestations of a seizure depend on the specific region and extent of brain involvement and may include an alteration in motor function, sensation, alertness, perception, autonomic function, or all of these. Any person can experience a seizure in the appropriate clinical setting (eg, meningitis, hypoglycemia, toxin ingestion), attesting to the …

Produção de patulina em maçã (Malus domestica Borkhausen), cultivares Gala e Fuji inoculadas com Penicillium spp.

A maçã (Malus domestica Borkhausen) é uma excelente fonte nutricional e de interesse econômico, sendo que a Região Sul do Brasil contribue com 90% da produção Nacional deste fruto com destaque aos cultivares Gala e Fuji. O objetivo deste estudo foi avaliar a produção de patulina nestes cultivares inoculados com Penicillium expansum NRRL 1172 e Penicillium variabile toxigênico, isolado de maçãs regionais. As frutas contaminadas foram mantidas em condições de tempo de armazenamento e temperatura que variaram respectivamente de 15 a 90 dias e de 0 a 25°C. A produção de patulina ocorreu em todas as combinações de armazenagem e temperaturas empregadas para o ensaio, independentemente dos cultivares. A produção de patulina foi negativa no 30º dia nas maçãs estocadas a 0°C inoculadas com P.expansum, mas o aumento de temperatura para 4°C restringiu a margem de segurança, causando positividade na produção da toxina para ambos os cultivares inoculados com as duas linhagens fúngicas, no mesmo período. Nas maçãs inoculadas com P. variabile ocorreu maior concentração de patulina (F=68,05) do que as contaminadas com P. expansum NRRL 1172 (F=26,0). O risco freqüente de produção de patulina nas temperaturas de refrigeração, indicaram a necessidade de melhor controle nos estágios de colheita e armazenagem de maçãs, a fim de evitar constante ingestão de toxina.