Hapten Design and Monoclonal Antibody to Fluoroacetamide, a Small and Highly Toxic Chemical.

Fluoroacetamide (FAM) is a small (77 Da) and highly toxic chemical, formerly used as a rodenticide and potentially as a poison by terrorists. Poisoning with FAM has occurred in humans, but few reliably rapid detection methods and antidotes have been reported. Therefore, producing a specific antibody to FAM is not only critical for the development of a fast diagnostic but also a potential treatment. However, achieving this goal is a great challenge, mainly due to the very low molecular weight of FAM. Here, we design two groups of FAM haptens for the first time, maximally exposing the fluorine or amino groups, with the aid of linear aliphatic or phenyl-contained spacer arms. Interestingly, whereas the hapten with fluorine at the far end of the hapten did not induce an antibody response to FAM, the hapten with an amino group at the far end and phenyl-contained spacer arm triggered a significantly specific antibody response. Finally, a monoclonal antibody (mAb) named 5D11 was successfully obtained with an IC50 value of 97 µg mL-1 and negligible cross-reactivities to the other nine functional and structural analogs.

Evaluation of resistance to natural poisoning by Amorimia septentrionalis in goats which had received sodium monofluoroacetate degrading bacteria / Avaliação da resistência à intoxicação natural por Amorimia septentrionalis em caprinos que receberam bactérias degradadoras de monofluoroacetato de sódio

Amorimia septentrionalis is an important sodium monofluoroacetate (MFA) containing plant that causes sudden death in ruminants in northeastern Brazil. MFA degrading bacteria are being used in the prevention against poisoning by this plant. The aim of this study was to evaluate if goats which had per os received MFA degrading bacteria remained resistant when exposed to natural poisoning by A. septentrionalis. Eighteen goats were randomly distributed into three groups: the goats of Group 1 previously received, during 40 days, a solution containing the bacteria Ralstonia sp. and Burkholderia sp., those goats in the Group 2 received the bacteria Paenibacillus sp. and Cupriavidus sp. and goats from Group 3 did not receive any bacteria. After the administration period, during 60 days, the animals of all groups were released to graze on a one hectare paddock, with significant amount of A. septentrionalis. They were observed daily for the spontaneous consumption of A. septentrionalis leaves and the occurrence of clinical signs of poisoning or sudden death. Goats from all groups consumed significant amounts of A. septentrionalis during the experimental period. Goats that did not receive MFA-degrading bacteria (Group 3) became sick and died from the 25th to the 27th day of the experiment, whereas the goats of the groups that received MFA-degrading bacteria showed only clinical sings when A. septentrionalis regrowth after the 55th day of the experiment. The days elapsed from field observation to death of Group 3 goats (25.5±0.9 days) were significantly lower (p<0.05) than Group 1 (58.6±1.3 days) and Group 2 (57.8±1.5 days). Thus, it can be concluded that administration of MFA degrading bacteria increases the resistance to natural poisoning by A. septentrionalis.(AU)

Amorimia septentrionalis que contém monofluoroacetato de sódio (MFA) é responsável pela ocorrência de mortes súbitas em ruminantes no nordeste do Brasil. Bactérias degradadoras desse composto estão sendo utilizadas na prevenção contra a intoxicação por essa planta. O objetivo deste estudo foi avaliar se caprinos que receberam, via oral, bactérias degradadoras de MFA permaneciam resistentes quando expostos a intoxicação natural por A. septentrionalis. Dezoito caprinos foram divididos em três grupos, os caprinos do Grupo 1 receberam anteriormente, durante 40 dias, uma solução contendo as bactérias Ralstonia sp. e Burkholderia sp., os do Grupo 2 receberam, também por 40 dias as bactérias Paenibacillus sp. e Cupriavidus sp. e os do Grupo 3 não receberam nenhuma bactéria. Após o período de administração, durante 60 dias, os animais de todos os grupos foram soltos para pastar em um piquete de um hectare, que apresentava uma quantidade significativa da planta. Diariamente eles foram observados quanto ao consumo espontâneo das folhas de A. septentrionalis e quanto à presença de sinais clínicos de intoxicação ou morte. Os caprinos de todos os grupos consumiram quantidades significantes da planta durante o período experimental. Os caprinos que não receberam as bactérias degradantes de MFA (Grupo 3) adoeceram e morreram entre o 25º e o 27º dia de experimento, enquanto que os que receberam as bactérias degradantes de MFA (Grupo 1 e 2) só apresentaram sinais clínicos no 55º dia de experimento, o que coincidiu com a rebrota da planta. Os dias transcorridos desde a observação a campo até a morte dos caprinos do Grupo 3 (25,5±0,9 dias) foram significativamente menores (p<0,05) que os do Grupo 1 (58,6±1,3 dias) e do Grupo 2 (57,8±1,5 dias). Com isso pode-se concluir que a administração de bactérias degradadoras de MFA aumenta à resistência a intoxicação natural por A. septentrionalis.(AU)

D-Serine rescues the deficits of hippocampal long-term potentiation and learning and memory induced by sodium fluoroacetate.

It is well known that bidirectional glia-neuron interactions play important roles in the neurophysiological and neuropathological processes. It is reported that impairing glial functions with sodium fluoroacetate (FAC) impaired hippocampal long-term depression (LTD) and spatial memory retrieval. However, it remains unknown whether FAC impairs hippocampal long-term potentiation (LTP) and learning and/or memory, and if so, whether pharmacological treatment with exogenous d-serine can recuse the impairment. Here, we reported that systemic administration of FAC (3mg/kg, i.p.) before training resulted in dramatic impairments of spatial learning and memory in water maze and fear memory in contextual fear conditioning. Furthermore, the behavioral deficits were accompanied by impaired LTP induction in the hippocampal CA1 area of brain slices. More importantly, exogenous d-serine treatment succeeded in recusing the deficits of hippocampal LTP and learning and memory induced by FAC. Together, these results suggest that astrocytic d-serine may be essential for hippocampal synaptic plasticity and memory, and that alteration of its levels may be relevant to the induction and potentially treatment of psychiatric and neurological disorders.

Calcium gluconate and sodium succinate for therapy of sodium fluoroacetate experimental intoxication in cats: clinical and electrocardiographic evaluation.

Sodium fluoroacetate (SFAC) or Compound 1080 is a potent rodenticide, largely used after 1946 for rodent and home pest control. The toxic effects of SFAC are caused by fluorocitrate action, a toxic metabolite, which has a competitive action with aconitase enzyme, leading to citrate accumulation and resulting in interference in energy production by Krebs cycle blockade. In the present study, domestic cats were intoxicated with oral doses of fluoroacetate (0.45 mg/kg). The intoxicated animals presented emesis, diarrhea with abdominal pain posture and an abdominal palpation, tachypnea, bilateral midriasis, hypothermia, hyperexcitability and convulsions. Blood gas analysis indicated decreased pH and bicarbonate levels. Serum ionized calcium was also decreased. ECG showed non-specific changes in ventricular repolarization and ventricular arrhythmias. The survival rate was 75% in the treated group with calcium gluconate and sodium succinate and 37.5% in the nontreated group.

Effects of acetamide on experimentally-induced Palicourea marcgravii (St Hill) poisoning in rats.

High indices of mortality in cattle have been reported in Brazil as a consequence of Palicourea marcgravii (Pm) acute intoxications. It has been established that Pm leaves contain monofluoroacetic acid (MFA), the active toxic principle of the plant. Rational therapy for MFA poisoning involves the use of a substance that might prevent fluorocitric acid formation. The present work was undertaken to verify if acetamide, a MFA antidote and an acetate donor, protects rats against both Pm and MFA intoxications. It was verified that acetamide protected rats from both convulsions and death. Future experiments should be carried out on cattle to examine the efficiency of acetamide, and particularly under field conditions.

Biochemical aspects of fluoroacetate poisoning in isolated rat kidney tubules: reversibility of inhibition of gluconeogenesis by alpha-ketoglutarate.

The effects of monofluoroacetate (FAC) on suspensions of isolated rat kidney tubules were investigated. FAC inhibited gluconeogenesis from lactate, pyruvate, fructose, dihydroxyacetone, alpha-ketoglutarate, and succinate. The gluconeogenesis from pyruvate, ketoglutarate, and lactate was less sensitive to FAC than that from other substrates. FAC also caused a decrease in oxygen consumption, hydroxybutyrate to acetoacetate ratio, alpha-ketoglutarate, ATP, and total adenine nucleotide content; the citrate content was increased. Addition of alpha-ketoglutarate, 5 mmol/l, caused a reversal of gluconeogenesis inhibition, an increase in ATP content, and a delay in citrate accumulation in isolated rat kidney tubules incubated with FAC.