Effect of Interleukin-10 on Tissue Damage Caused by Organophosphate Poisoning

Organophosphate poisoning is a common cause of severe morbidity and mortality among patients admitted to emergency departments. Tissue damages as a consequence of organophosphate poisoning are frequently reported, but preventing this potentially severe complication has not been the subject of much research. We tested whether interleukin-10, a cytoprotective agent, could prevent or diminish pathological signs of tissue damages caused by organophosphate poisoning. Thirty rats were divided into three equal groups (n = 10). Group 1 (sham) did not receive any agent during the experiment. Group 2 (control) received 0.8 g/kg of fenthion intraperitoneally, followed by 6 ml/kg of intraperitoneal normal saline 30 min and 3 hr later. Group 3 (treatment) received 0.8 g/kg of fenthion intraperitoneally, followed by 2 microg/kg of interleukin-10 intraperitoneally 30 min and 3 hr later. All rats were killed under anaesthesia after 6 hr and tissue samples were obtained from liver, kidneys and lungs. Even organophosphate poisonings do not cause significant clinical problems; several degrees of damages could be observed in liver, kidneys and lungs. These damages could be reduced by interleukin-10 treatment.

Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study

BACKGROUND

Although more than 100 organophosphorus insecticides exist, organophosphorus poisoning is usually regarded as a single entity, distinguished only by the compound's lethal dose in animals. We aimed to determine whether the three most common organophosphorus insecticides used for self-poisoning in Sri Lanka differ in the clinical features and severity of poisoning they cause.

METHODS

We prospectively studied 802 patients with chlorpyrifos, dimethoate, or fenthion self-poisoning admitted to three hospitals. Blood cholinesterase activity and insecticide concentration were measured to determine the compound and the patients' response to insecticide and therapy. We recorded clinical outcomes for each patient.

FINDINGS

Compared with chlorpyrifos (35 of 439, 8.0%), the proportion dying was significantly higher with dimethoate (61 of 264, 23.1%, odds ratio [OR] 3.5, 95% CI 2.2-5.4) or fenthion (16 of 99, 16.2%, OR 2.2, 1.2-4.2), as was the proportion requiring endotracheal intubation (66 of 439 for chlorpyrifos, 15.0%; 93 of 264 for dimethoate, 35.2%, OR 3.1, 2.1-4.4; 31 of 99 for fenthion, 31.3%, 2.6, 1.6-4.2). Dimethoate-poisoned patients died sooner than those ingesting other pesticides and often from hypotensive shock. Fenthion poisoning initially caused few symptoms but many patients subsequently required intubation. Acetylcholinesterase inhibited by fenthion or dimethoate responded poorly to pralidoxime treatment compared with chlorpyrifos-inhibited acetylcholinesterase.

INTERPRETATION

Organophosphorus insecticide poisoning is not a single entity, with substantial variability in clinical course, response to oximes, and outcome. Animal toxicity does not predict human toxicity since, although chlorpyrifos is generally the most toxic in rats, it is least toxic in people. Each organophosphorus insecticide should be considered as an individual poison and, consequently, patients might benefit from management protocols developed for particular organophosphorus insecticides.

Effect of interleukin-10 on pancreatic damage caused by organophosphate poisoning

Organophosphate poisoning is a common cause of severe morbidity and mortality in emergency departments. Acute pancreatitis is a frequently reported consequence of organophosphate poisoning, but preventing this potentially severe complication has not been the subject of much research. We tested whether interleukin-10, a cytoprotective agent, could prevent or diminish pathological signs of acute pancreatitis caused by organophosphate poisoning. Thirty rats were divided into three equal groups. Group 1 did not receive any agent during the experiment. Group 2 received 0.8 g/kg fenthion intraperitoneally, followed by 6 ml/kg intraperitoneal normal saline 30 min and 3 h later. Group 3 received 0.8 g/kg fenthion intraperitoneally, followed by 2 microg/kg of interleukin-10 intraperitoneally 30 min and 3 h later. All rats underwent laparotomy and thoracotomy while still under anesthesia at 6 h, and tissue samples were obtained from the pancreas. After blood samples were taken by cardiac puncture, the animals were sacrificed. Organophosphate poisoning resulted in significant elevations of serum amylase and glucose. Interleukin-10 significantly reduced pancreatic damage as determined by pathologic scoring, but not by enzyme elevations. Interleukin-10 should be considered for larger studies in other animal models to confirm its ability to decrease pancreatic damage after organophosphate poisoning treatment with interleukin-10.

Systemic organophosphate poisoning following the percutaneous injection of insecticide. Case report

Organophosphates are the most common group of chemicals in the southern part of Turkey. Although organophosphate poisoning (OPP) may occur due to skin exposure or inhalation, severe poisoning is usually the result of ingestion to attempt suicide. Despite the fact that there have been a lot of experimental studies using intravenous or percutaneous injection of organophosphates, reports of human poisoning due to percutaneous injection are rare. The systemic signs of OPP have not been described in these reported patients. We report 2 cases having systemic signs of OPP due to percutaneous injection. In our first case, we noticed a 17-day muscle weakness and a 12-day muscarinic syndrome, which required prolonged atropinization. In the second patient, atropine infusion had to be continued for 2 days. Both cases also had severe swelling of the affected limb and wound infection. In conclusion, in cases of percutaneous injection of organophosphates systemic toxicity may develop in addition to local findings such as necrosis and abscesses. Close observation for evidence of systemic involvement is required, and the patient should be carefully monitored for secondary abscess formation and any delayed impairment of neurologic function.

Severe fenthion intoxications due to ingestion and inhalation with survival outcome

Two cases of severe fenthion intoxication are presented. The first is a case of a psychiatric patient who attempted suicide with ingestion of the compound, and the second case was of a child exposed to the chemical agent by air spraying. Both patients were treated in the intensive care unit with atropine and pralidoxime and finally survived. Fenthion blood levels on admission were 2.7 and 0.95 microg/mL, respectively. Different concentrations of pralidoxime were added to the first patient's poisoned serum in order to assess in vitro the effect of pralidoxime on cholinesterase reactivation. The clinical and toxicological data of the poisonings are discussed, as well as the potential therapeutic use of pralidoxime in organophosphate intoxication.

Parasuicide by self-injection of an organophosphate insecticide

Parasuicide by ingestion of organophosphate (OP) insecticides is common in Sri Lanka, but the use of the parateral route to self administer the poison is extremely rare. We report a patient who deliberately injected herself intramuscularly with an OP compound with suicidal intent. The clinical manifestations of OP poisoning were unpredictable and posed a therapeutic problem.

Clinical and toxicological data in fenthion and omethoate acute poisoning

This study paper reports on two cases of poisoning with the organophosphorus insecticides, fenthion and omethoate. The two victims were admitted in the Intensive Care Unit (ICU) a few hours after ingestion of the two insecticides. They received appropriate treatment for organophosphorous poisoning (gastric lavage, activated charcoal, atropine and pralidoxime) and supportive care. Both patients survived. Organophosphate blood levels were determined on admission (fenthion 2.9 micrograms/ml, omethoate 1.6 micrograms/ml) and during the hospitalisation and proved to be considerably high. Slow elimination rate of the poison already distributed in the body was indicated for both pesticides. The patient with omethoate poisoning remained clinically well (Glasgow Coma Scale: 15) and was discharged three days later. The patient with fenthion poisoning, who had also ingested 30 mg of bromazepam and 720 mg of oxetoron, developed cholinergic crisis six hours after admission and was intubated for 24 days, with concomitant complications.

Analysis of fenthion in postmortem samples by HPLC with diode-array detection and GC-MS using solid-phase extraction

Fenthion (O,O-dimethyl-O-[3-methyl-4-(methylthio)-phenyl]-thiophos-phate ) is an organophosphate insecticide. A specific method to quantitate fenthion in postmortem matrices with solid-phase extraction combined with high-performance liquid chromatography-diode-array detection (HPLC-DAD) and gas chromatography-mass spectrometry (GC-MS) is presented. Fenitrothion (O,O-dimethyl-O-[3-methyl-4-nitrophenyl]-thiophosphate) is selected as the internal standard. For sample cleanup, a simple but selective solid-phase extraction is chosen after comparison with traditional liquid-liquid extraction procedures. Homogenized and appropriately diluted aqueous samples are applied, and the analytes are desorbed with 5 mL of dichloromethane. Aliquots of the extract are used for HPLC-DAD and GC-MS analysis, Liquid and GC conditions are as follows: gradient elution with a mixture of methanol and water (10:90 to 90:10, v/v) containing 0.0125M NaOH on an Aluspher RP-Select B column monitoring at 250 nm, and temperature programming from 60 to 300 degrees C on a dimethylpolysiloxane column in the SCAN mode, respectively. This method is applied to a suicidal case involving unsuspected acute intoxication with fenthion (concentration in blood, 3.8 micrograms/mL).

Experiences with acute organophosphate poisonings in Crete

Nine human acute poisonings due to intentional ingestion of organophosphorous pesticides are presented. Six of the victims died. Six patients were treated in the Intensive Care Unit (ICU) from 34 h to 45 d, while 3 were found dead by relatives. Two of the patients treated in the ICU fully recovered after 15 and 24 d while the third survivor developed delayed neuropathy. Organophosphate blood levels were determined on admission and during therapy, and in 1 case atropine and pralidoxime levels were also detected. Significant fluctuations of the plasma cholinesterase activity were observed during therapy. Postmortem analysis revealed higher levels of pesticides in organs (eg 23.1 micrograms fenthion/g kidney) and in fat (135.2 micrograms fenthion/g) than in blood (eg 4.8 micrograms fenthion/ml) and vitreous humor. Considerable pesticide was measured in testis (eg 5.8 micrograms fenthion/g, 0.8 micrograms methidathion/g) and uterus (170.5 micrograms malathion/g). Extracorporeal decontamination to enhance pesticide elimination is a therapeutic challenge.

Extrapyramidal manifestations complicating organophosphorus insecticide poisoning

Six patients who developed extrapyramidal manifestations following poisoning with the organophosphorus (OP) insecticide fenthion are reported. The extrapyramidal features, in order of frequency, were dystonia, rest tremor, cog-wheel rigidity, and choreo-athetosis. The delay in onset of these signs, following poisoning, varied from 4 to 40 days, and they disappeared spontaneously in about 1 to 4 weeks in those who survived. The human extrapyramidal system is rich in cholinergic neurons and acetylcholinesterase (AChE). Inhibition of AChE by fenthion, which has ready access to central neurons on account of its lipid solubility, is postulated as the mechanism underlying the extrapyramidal manifestations.

The intermediate syndrome in organophosphate poisoning: an overview of experimental and clinical observations

The intermediate syndrome of organophosphate poisoning arises in the time interval between the acute cholinergic crisis of fasciculations and muscle weakness and the delayed neuropathy attributed to inhibition of the neuropathy target esterase. The conclusions derived from salient experimental and clinical studies are that intermediate syndrome relates to the severity of poisoning not the specific organophosphate and to prolonged inhibition of acetylcholinesterase activity of the erythrocytes, brain and muscle endplate with pre and post synaptic impairment of neuromuscular transmission. It is not related to delayed neuropathy.

Organophosphate poisoning: peripheral vascular resistance--a measure of adequate atropinization

We report severe organophosphate poisoning complicated by hypotension and ischemic sequelae in two patients with pre-existing vascular disease. Both patients had a low total peripheral resistance and high cardiac output that were significantly reversed by doses of atropine in excess of those required to control other muscarinic symptoms. Cerebral infarcts and gangrene requiring a below knee amputation were complications of the poisonings. It is proposed that the ischemic complications are due to paradoxical vasoconstriction by acetylcholine at sites of endothelial injury. One patient, who had taken fenthion, also had a significantly delayed peak and prolonged, 2-3 week, systemic toxicity. We propose that stability of the plasma cholinesterase at 6 to 8 h after temporarily suspending oxime provides a rapid guide to the duration of therapy, especially in patients whose complications make clinical assessment difficult.

The neurophysiologic examination in organophosphate ester poisoning. Case report and review of the literature

A 65-year-old woman who has been admitted after organophosphate-induced poisoning (Fenthion), develops pareses as a result of neuromuscular junctional dysfunction 7 days post-exposure. These findings are consistent with an intermediate syndrome, which may appear within 24 to 96 hours of exposure and subsides after 5 to 18 days. Delayed polyneuropathy develops within 1 to 3 weeks and abates after 6 to 12 months. A distal axonopathy can be demonstrated. Several authors have attempted EMG monitoring of pesticide-workers in agricultural and industrial settings. The electrophysiologic examination is an important diagnostic adjunct in the development and course of muscle paresis following organophosphate-ester poising.

Postsynaptic neuromuscular dysfunction in organophosphate induced intermediate syndrome

A 65-year-old Caucasian female developed an intermediate syndrome seven days after an acute cholinergic crisis, caused by the ingestion of fenthion. Cholinesterase activity in the blood, plasma and red cells was monitored daily by the method according to Nenner and serial serum fenthion levels were measured by capillary gas chromatography. Electromyographic studies showed fade on tetanic stimulation by means of surface electrodes at 20 Hz of the left M. abductor digiti quinti at day 7, which could no longer be observed at day 19. Fade on low-frequency stimulation and post-tetanic facilitation were both absent. A biopsy of the N. suralis was normal. A biopsy of the M. tibialis anterior revealed a limited rhabdomyolysis with a very weak staining for cholinesterase. It is hypothesized that the pathophysiologic process underlying the syndrome is the result of a time-confined phenomenon, which includes both changes in the postsynaptic structures by a desensitization process and a gradually restoring ratio of acetylcholine to acetylcholinesterase. This hypothesis is suggested by the similarity in the EMG-findings of this patient and those in myasthenia gravis, which is known to be characterized by a postsynaptic transmission defect.

[Chronic organophosphorus intoxication and aging in rats]

Possible acceleration of aging due to the administration of organophosphorus pesticide (OP) was studied. Fenthion (6 mg/kg/day) was subcutaneously administered dorsally to rats over a period of 12 weeks. The amounts of fluorescent lipid peroxidation products (FLPP) and superoxide dismutase (SOD) activity were measured in various tissues. Microscopic examination was added only in the lens. The amount of FLPP in the retina-choroid, lens, kidney and heart of the rats was found to be increased (lens; p less than 0.01, kidney; p less than 0.05). The activity of SOD in the retina-choroid, optic nerve, liver and heart increased temporarily, but eventually returned to control levels. The lens preparations at the end of the 12-week administration period showed irregular bow configuration and epithelial nuclear dislocation in the bow area. FLPP are fluorescent products produced by peroxide lipids and their amounts increase with aging. Increase in the amounts of these products and microscopic findings for the lens were indications of the progress of aging. There is thus the possibility that the inducement of SOD production may decrease with aging. It was concluded that the organophosphorus pesticide may accelerate the aging of rats.

Prompt recovery from severe cholinesterase-inhibitor poisoning--remarks on classification and therapy of organophosphate poisoning

In organophosphate intoxication the assessment of both the degree of severity of poisoning and the initial dose of pralidoxime and atropine are as yet based only on clinical symptoms. We present three patients with clinically severe organophosphate poisoning in whom a prompt recovery from central nervous symptoms occurred after the administration of low doses of atropine and pralidoxime. It is suggested that the true severity of organophosphate intoxication as well as the initial therapy should be determined by the amount ingested, the propensity for aging, and the pharmacodynamic properties of the organophosphorus compound, as well as by the time interval between exposure and initiation of appropriate treatment, as far as these data can be verified in the individual patient.

Acute organophosphorus insecticide poisoning during pregnancy

Intoxication with organophosphorus insecticides following ingestion with suicidal intent in two patients who were in the second and third trimesters of pregnancy is reported. Successful management of the cholinergic and intermediate phases of poisoning enabled each pregnancy to proceed to term and end in normal vaginal delivery of a healthy baby.

Selected neurotoxins

The small animal practitioner is faced with an infinite number of potential toxins in our modern environment. Unapproved usage of drugs and insecticides requires the practitioner to keep informed about the development of new toxic syndromes. Recreational drug toxicosis in animals is still seen with some frequency in clinical practice and should not be overlooked, even when the owner denies the possible exposure. In this article, we have discussed a few of the more common and newer neurotoxicities seen in clinical practice today. Neurologic toxicities are complex, but treatment can be rewarding if early diagnosis is made and aggressive therapy is instituted. The practitioner will find it worthwhile to establish contact with a toxicologist or poison information center for additional support when necessary.

Case histories of bald eagles and other raptors killed by organophosphorus insecticides topically applied to livestock

Since 1982 when secondary poisoning of a red-tailed hawk (Buteo jamaicensis) was documented following the recommended use of famphur applied topically to cattle, the Patuxent Wildlife Research Center has tested dead birds of prey for poisoning by famphur and other pour-on organophosphorus (OP) insecticides. Brain cholinesterase (ChE) activity was first determined, then if ChE was depressed greater than or equal to 50%, stomach and/or crop contents were evaluated for anti-ChE compounds. This report presents the circumstances surrounding the OP-caused deaths of eight bald eagles (Haliaeetus leucocephalus), two red-tailed hawks, and one great horned owl (Bubo virginianus) between March 1984 and March 1985. OP poisoning of raptors by pour-on insecticides in the United States is widespread, but its magnitude is unknown.

Neurotoxic effects of organophosphorus insecticides. An intermediate syndrome

Acute neurotoxic effects during the cholinergic phase of organophosphorus insecticide poisoning and delayed neurotoxic effects appearing two to three weeks later are well recognized. We observed 10 patients who had paralysis of proximal limb muscles, neck flexors, motor cranial nerves, and respiratory muscles 24 to 96 hours after poisoning, after a well-defined cholinergic phase. The compounds involved were fenthion, monocrotophos, dimethoate, and methamidophos. Four patients urgently required ventilatory support. The paralytic symptoms lasted up to 18 days. A delayed polyneuropathy later developed in one patient. Three patients died. Electromyographic studies showed fade on tetanic stimulation, absence of fade on low-frequency stimulation, and absence of post-tetanic facilitation, suggestive of a postsynaptic defect. This neuromuscular junctional defect may have been the predominant cause of the paralytic symptoms, with neural and central components contributing to various degrees. Our patients appeared to have a distinct clinical entity (a so-called intermediate syndrome) that developed after the acute cholinergic crisis and before the expected onset of the delayed neuropathy.

Prolonged toxicity of organophosphate poisoning

A case of poisoning with a new organophosphate (fenthion) is reported in which the initial cholinergic crisis was delayed 5 days and recurred 24 days after ingestion. Psychosis was a persistent and sometimes singular manifestation. Because of the high lipid solubility of this pesticide, toxin analysis of repeated fat biopsies was an essential component of the management of this patient.

Severe and prolonged poisoning by fenthion. Significance of the determination of the anticholinesterase capacity of plasma

A case of acute poisoning by oral ingestion of fenthion is reported. The different clinical signs, especially the delayed and prolonged symptomatology, are described. The various types of therapeutic measures (gastric lavage with charcoal, administration of atropine, Toxogonine, lyophilized human cholinesterase, and fresh plasma and exchange transfusion) are discussed. Correlation studies between clinical signs and plasma and erythrocyte cholinesterase activities are presented together with plasma fenthion levels and the anticholinesterase capacity of the patient's plasmas.

Possible fenthion toxicity in magpies (Pica pica)

Unusual mortality in magpies (Pica pica) is described. Dead or sick birds were discovered in proximity to cattle in Alberta feedlots. Subsequent examinations indicated magpies were being exposed to fenthion, an organophosphate used on cattle for control of warble larvae and lice. The possibility of toxicity with fenthion is suggested.

[Sensitivity of the females of Ixodes persulcatus and Dermacentor silvarum (Ixodidae) to baytex and the possibility of their overcoming poisoning with this substance]

Females of I. persulcatus and D. silvarum are very sensitive to baytex, the value of LD50 for both species are similar. The development of injury after exposure to baytex proceeds very quickly and the subsequent stages of injury development correspond to those caused by DDT (Uspensky and Levikov, 1974). The overcoming of baytex poisoning during the sucking of the host's blood is possible only at the initial stage of the injury. The simulatneous feeding on the same rabbit of ticks treated with baytex and control ones has shown a system effect of baytex on the second group of ticks.

Evaluation of hazards involved in treating cattle with pour-on organophosphate insecticides

Eighteen veterinarians regularly practicing organophosphate pour-on treatment of cattle for grub infestations were examined in the course of the 1975-1976 application season for symptoms and signs as well as enzymologic and chemical evidence of organophosphate absorption. Some subjects reported headache, nausea, and irritation of the face and throat during chemical applications in poorly ventilated buildings. Organophosphate absorption was not sufficient to depress blood cholinesterase activities, and only occasionally generated measurable amounts of alkyl phosphate meatbolites in urine of exposed veterinarians.