Fluoracetate Research Articles

Modulation by Astrocytes of AMPA Currents in the NTS Neurons of Mice Is Reduced by Short Term-Sustained Hypoxia

Hypoxia due to reduction in the partial pressure of oxygen in the arterial blood (PaO2) activates the afferents of peripheral chemoreflex to produce cardiovascular and respiratory adjustments to bring PaO2 back to the normal range. Herein we evaluated the possible changes of astrocytic modulation on glutamatergic transmission in NTS neurons of mice submitted to short term-sustained hypoxia (SH). To reach this goal, we used Male C57Bl/6J mice (18-20g), which were submitted to SH (FiO2 0.1) or normoxia for 24 hours. Brainstem slices and whole-cell patch clamp technique were used to evaluate the synaptic transmission in NTS neurons. The intracellular calcium concentration in NTS astrocytes was evaluated by multiphoton microscopy and transgenic Aldh-CRE-GCAMP6f mice (Institutional Ethical Committee Approvals: #016/2018 and #1109/2022R1). SH increased the amplitude of TS-evoked AMPA currents [control: -72.8 ± 13.3 pA ( n = 12) vs SH: -120 ± 14.4 pA ( n = 21)] in NTS neurons with no changes on the rise- or decay-time. SH also increased the amplitude [control: 35.88 ± 7.9 pA ( n = 12) vs SH: 72.74 ± 15.47 pA ( n = 10)] and decay time [control: 61.8 ± 15.2 ms ( n = 9) vs SH: 286 ± 86.7 ms ( n = 10)] of TS evoked-NMDA currents in neurons, while the amplitude of extrasynaptic NMDA currents [control: 28.7 ± 7.4 pA ( n = 10) vs SH: 24.7 ± 3.2 pA ( n = 7)] was not affected. Perfusion with fluoracetate (FAC), a glial metabolism inhibitor, decreased the amplitude of TS-evoked AMPA currents in control group [aCSF: -54.29 ± 16.1 pA vs aCSF + FAC: -24.43 ± 6.82 pA ( n =9)] without affecting AMPA currents in SH neurons [aCSF: -124.5 ± 35.27 pA vs aCSF + FAC: -130.5 ± 50.16 pA ( n =8)]. The passive properties of astrocytes did not change after SH [RMP: -83.73 ± 11.85 mV ( n =10) vs −83.63 ± 11.86 mV ( n =10); Rinput: 123 ± 127.5 MΩ ( n =9) vs 208 ± 212.7 MΩ ( n =10)]. The increase in intracellular calcium concentration induced by AMPA in the astrocytes of control and SH mice was similar [Control: 112.8 ± 15.41 ΔF/F0 (n=68 ROIs) vs SH: 56.38 ± 18.31 ΔF/F0 (n=13 ROIs)]. The data shows that SH increased the evoked glutamatergic currents in NTS neurons of mice, probably due to a reduction in the astrocytic modulation of excitatory transmission by mechanisms apparently independent of astrocytic intracellular calcium. FAPESP (2018/15957-2, 2018/02336-0 and 2022/05237-8), CNPq (309338/2020-4) and CAPES-PROEX (23038.006922/2021-31). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Sodium fluoracetate's poisoning: A case report


 Introduction: Sodium fluoroacetate, known as compound 1080, was discovered in Germany during the Second World War. It is usually used as a rodenticide, it is an odorless and tasteless substance, with a lethal dose in humans of 2 mg / kg that is why it was withdrawn from the market in some countries, including Colombia; however, it is obtained illegally. This substance has biochemical and physiological effects at the cellular level that alter the transport of citrate at the mitochondrial level, generating accumulation of lactic acid and alteration of the glucose use. The clinical manifestations are nonspecific since there is no any cardinal symptom. Therefore, its diagnosis is made due to high clinical suspicion associated with establishment of exposure to the compound in view of the difficulty to obtain paraclinical confirmation in a timely manner.
 Methods: We present a case report of intentional ingestion of sodium fluoroacetate in an adolescent that is associated with an infection added to the bloodstream by methicillin- sensitive Staphylococcus aureus (MSSA). The patient developed multiple complications that lead to support in the Intensive Care Unit (ICU) with a satisfactory outcome. In view of the lack of a specific antidote, she was treated with ethanol in order to increase the level of acetate; thus, offering an alternative substrate to the Krebs cycle. It is suggested that the ethanol offers benefits in the acute treatment of these patients.
 Results: The patient with sodium fluoroacetate poisoning and kidney failure received renal replacement therapy with a favorable evolution and survival at discharge from the intensive care unit of a third-level hospital in the city of Pereira, Risaralda, Colombia.
 Conclusions: Sodium fluoroacetate poisoning is relatively rare and can cause acute kidney injury and multi-organ failure with a high rate of complications and death. A case of self-inflicted poisoning that received a timely manner continuous renal replacement therapy with a favorable outcome in terms of ICU survival was presented.

Astrocytic modulation of IKA, NMDA and AMPA currents in NTS neurons of rats is affected by sustained hypoxia

Short term sustained hypoxia (SH, FiO2 0.1, 24 h) produces cardiovascular and respiratory changes mainly due to peripheral chemoreflex activation. SH alters the electrophysiological properties of neurons in the NTS, where the first synapses of chemoreflex afferents are located. In the present study we evaluated alterations produced by SH on neuronal excitability and excitatory synaptic transmission in the NTS neurons integral to chemoreflex pathways. After SH protocol, brainstem slices were obtained for electrophysiological recordings using whole cell patch–clamp and fluoracetate (FAC) was used to produce metabolic inhibition of astrocytes. SH increased the action potential discharge in response to positive injected current into NTS neurons (p=0.0048). The presence of A‐type potassium current (IKA) was observed and its peak amplitude was larger in neurons from control [Vm = 10 mV, 1428 ± 600 pA (n=10)] than in SH rats [Vm = 10 mV, 334 ± 76 pA (n=10)]. Inhibition of astrocytes with FAC decreased the IKA amplitude in neurons from control rats [1227 ± 129 pA vs 605 ± 210 pA (n=7)], but not in SH rats [475 ± 110 pA vs 427 ± 114 pA (n=6)]. With respect to excitatory neurotransmission, SH increased AMPA/kainate [−183 ± 122 pA (n=10) vs −353 ± 101 pA (n=10)] and NMDA currents amplitude [61 ± 10 pA (n=7) vs 102 ± 37 pA (n=10)]. Astrocytic modulation on AMPA [aCSF: −353 ± 101 pA vs aCSF + FAC: −369 ± 76 pA, (n=10)] and NMDA currents [aCSF: 102 ± 37 pA vs aCSF + FAC: 108 ± 32 pA, (n=10)] was blunted by SH. In addition, SH increased AMPA current density [control: −6 ± 3.5 pA/pF (n=6) vs SH: −20 ± 12 pA/pF (n=7)]. The data shows that astrocyte modulation of synaptic transmission in NTS neurons integral to the chemoreflex pathways is reduced by SH, which may contribute to the observed increase in the chemoreflex responsiveness on this experimental model.Support or Funding InformationFAPESP, CAPES and CNPq

Glial cells modulate the synaptic transmission of NTS neurons sending projections to ventral medulla of Wistar rats.

There is evidence that sympathoexcitatory and respiratory responses to chemoreflex activation involve ventrolateral medulla-projecting nucleus tractus solitarius (NTS) neurons (NTS-VLM neurons) and also that ATP modulates this neurotransmission. Here, we evaluated whether or not astrocytes is the source of endogenous ATP modulating the synaptic transmission in NTS-VLM neurons. Synaptic activities of putative astrocytes or NTS-VLM neurons were recorded using whole cell patch clamp. Tractus solitarius (TS) stimulation induced TS-evoked excitatory postsynaptic currents (TS-eEPSCs) in NTS-VLM neurons as well in NTS putative astrocytes, which were also identified by previous labeling. Fluoracetate (FAC), an inhibitor of glial metabolism, reduced TS-eEPSCs amplitude (−85.6 ± 16 vs. −39 ± 7.1 pA, n = 12) and sEPSCs frequency (2.8 ± 0.5 vs. 1.8 ± 0.46 Hz, n = 10) in recorded NTS-VLM neurons, indicating a gliomodulation of glutamatergic currents. To verify the involvement of endogenous ATP a purinergic antagonist was used, which reduced the TS-eEPSCs amplitude (−207 ± 50 vs. −149 ± 50 pA, n = 6), the sEPSCs frequency (1.19 ± 0.2 vs. 0.62 ± 0.11 Hz, n = 6), and increased the paired-pulse ratio (PPR) values (∼20%) in NTS-VLM neurons. Simultaneous perfusion of Pyridoxalphosphate-6-azophenyl-2′,5′-disulfonic acid (iso-PPADS) and FAC produced reduction in TS-eEPSCs similar to that observed with iso-PPADS or FAC alone, indicating that glial cells are the source of ATP released after TS stimulation. Extracellular ATP measurement showed that FAC reduced evoked and spontaneous ATP release. All together these data show that putative astrocytes are the source of endogenous ATP, which via activation of presynaptic P2X receptors, facilitates the evoked glutamate release and increases the synaptic transmission efficacy in the NTS-VLM neurons probably involved with the peripheral chemoreflex pathways.

A Review of the Impact of Sheep Predators in Australia and New Control Methods Under Development

Author(s): Lapidge, Steven; Dall, David; Hunt, Rob; Cowled, Brendan; Smith, Michelle; Staples, Linton | Abstract: The economic impact of introduced predators, principally wild dogs, foxes, and feral pigs, on agriculture in Australia varies across space and time but is estimated to be in excess of US$120 million annually. Australian farmers and the government spend a further US$30 million annually attempting to manage the predation and disease impacts of introduced predators on stock and wildlife. The principal chemical tool used to control each of these species is sodium fluoroacetate (‘1080’). Issues relating to target-specificity and perceived inhumaneness of the toxin have led to heavily restricted use of the compound in the U.S. and a recent registration review in Australia. Three current proactive research projects are addressing this issue. The first is investigating a chemical, p-aminopropiophenone or PAPP, that appears to be selectively toxic for introduced carnivores, as well as rapid acting and relatively humane in its mode of action. The compound acts by interfering with oxygen transport in the blood of foxes and wild dogs, resulting in an effect similar to carbon monoxide poisoning. The second project involves testing and commercializing powerful fox, wild dog, and feral pig attractants that may help increase the efficacy and target-specificity of control programs. The first product from this project is FeralMone®, an aerosolized formulation of synthetic fermented egg that is highly attractive to canids. The third project has involved developing a manufactured target-specific feral pig bait package, PIGOUT®. Initial research has focused on the delivery vehicle that contains sodium fluoracetate centralized in an internal core, whilst current research is developing a recently identified humane alternative feral pig control agent. This paper will report on the economic impact of introduced predators in Australia, the recent Australian sodium fluoroacetate review recommendations, as well as summaries of current research into new predator control tools.

The effect of dingo control on sheep and beef cattle in Queensland

Summary Predation by dingoes Canis lupus dingo is regarded as a widespread problem by Australian livestock producers. This study examined five decades of historical data to evaluate the use and effect of dingo control on the distribution of sheep and beef cattle in Queensland. In Queensland, dingo bounties were significantly more numerous in years with high sheep numbers but significantly less numerous in years with high beef cattle numbers. These relationships probably reflected the social and economic attitudes of the two producer groups to dingoes. The relatively high impact that dingoes are perceived to have on sheep compared with beef cattle, the control techniques used by the two producer groups, and the intensity at which these techniques are applied, were the underlying causes. Subsequent to the introduction of baiting using 1080 (sodium fluoracetate), there was an immediate decline in the use of strychnine, the number of dingo bounties presented for payment, and the number of dingo trappers employed by local governments in Queensland. However, these changes were confounded by a simultaneous decline in sheep numbers and dingo control effort. Barrier fences and poisoned ‘buffers’ were compared for their ability to protect sheep from dingo predation. With few exceptions, sheep numbers declined or increased marginally within 50 km inside a dingo barrier fence or within a boundary between sheep and beef cattle production outside the dingo barrier fence. This contrasted to areas > 50 km from the dingo barrier fence or sheep/cattle boundary. Both poisoned buffers and barrier fences could be equally effective at preventing sheep losses. However, buffers are best suited to open arid areas where large‐scale co‐ordinated baiting programmes are more feasible and where prey scarcity leads to increased bait consumption. We predict that sheep production outside the dingo barrier fence in Queensland will contract from the north and east. There is a case for re‐establishing a barrier fence in this area to prevent such contraction. Co‐ordinated predator management, such as barrier fencing or aerial baiting, can protect sheep at a regional level. However, unless the financial burden of pest control is shared through a centralized scheme, sheep producers living along the boundary are likely to leave the industry or substitute cattle for sheep and the sheep‐production area will contract. This paper cautions the use of bounties as a measure of relative abundance and illustrates how people’s perception of a pest and the type of livestock they produce can affect their level of control effort and the control methods they use.

Evaluation of the Efficacy of 1080 Poisoning of Red Foxes Using Visitation to Non-Toxic Baits as an Index of Fox Abundance.

Visits of foxes to non-toxic baits were used to derive fox abundance indices at 4 sites in north-eastern New South Wales. A 1080 (sodium fluoracetate) poisoning campaign resulted in a mean population reduction of 69.5% (s.d. = 4.9). Fox densities before baiting, calculated using the index-removal-index method, ranged from 4.55 to 7.16 foxes km-2. Visitation to non-toxic baits is recommended as a reliable estimate of relative density. This study investigated the efficacy of 1080 baiting as a technique for the control of foxes in tableland environments. The implications of the estimated fox densities and population reductions on fox control in agricultural areas and in the context of rabies are discussed.

Schistosomatium douthitti: Carbohydrate metabolism in the adults

Pathways of carbohydrate metabolism in the adults of Schistosomatium douthitti: were investigated. Histochemical reactions for adenosinetriphosphatase (EC 3.6.1.3) glucose 6-phosphate dehydrogenase (EC 1.1.1.49), phosphogluconate dehydrogenase (EC 1.1.1.43), glycerol-3-phosphate dehydrogenase (EC 1.1.1.8), lactate dehydrogenase (EC 1.1.1.27, 1.1.2.3) isocitrate dehydrogenase (EC 1.1.1.41), succinate dehydrogenase (EC 1.3.99.1), malate dehydrogenase (EC 1.1.1.37), cytochrome oxidase (EC 1.9.3.1), and adenosine triphosphatase (EC 3.6.1.3) were found in the adult worms. Glycogen deposits occurred in the parenchyma. Low oxygen tension immobilized the worms. Tartar emetic, sodium cyanide reduced adult motility in vitro. Manometric experiments demonstrated a respiratory quotient of approximately one. Oxygen uptake was completely inhibited by tartar emetic and partially inhibited by sodium fluoracetate and sodium cyanide. Inhibition by sodium fluoroacetate was partially counteracted by citric acid in the medium. Adults demonstrated an oxygen debt following anaerobic incubation. A maximum of 52% of the glucose consumed under aerobic conditions was excreted as lactic acid. Under anaerobic conditions the amount of lactic acid excreted increased. Acids other than lactic acid were also released. Results indicate that although glycolysis is the major pathway, two additional aerobic pathways also exist, one which is cyanide sensitive and the other cyanide insensitive.

Sodium fluoracetate and fluoracetamide as 'direct' posions for the control of rats in sewers.

1. Field trials suggest that 3-monthly operations against rats in sewers using either 0·25% sodium fluoracetate or 2% fluoracetamide as a direct poison are more effective than 6-monthly treatments with 2·5% zinc phosphide or 10% arsenious oxide using the pre-baiting method.2. In six paired trials 2% fluoracetamide gave better results (an apparent 100% clearance in five instances) than 0·25% sodium fluoracetate.3. There is no evidence, at present, that direct poisoning treatments with 2% fluoracetamide or 0·25% sodium fluoracetate are improved by the addition of mould inhibiting substances to the bait.The work described above was made possible only by the co-operation of a large number of local authority councils and their staffs, to whom we are therefore much indebted. We wish to thank also, Mr J. D. Riley who gave considerable help during the early stages of the trials.

Some properties of fluoracetamide as a rodenticide.

1. The average lethal dose of fluoracetamide for wild R. norvegicus was found to be 13 mg./kg. of body weight and the LD95, about 43 mg./kg.2. Wild rats offered bait contatining 0·5, 1 and 2% fluoracetamide, after a period of conditioning, seemed to find it palatable and, on the average, ingested the equivalent of 18–100 LD50's. Warning symptoms appeared in about an hour or longer and included short convulsive spasms.3. The speed of onset of warning symptoms leading to cessation of feeding was studied in albino rats dosed with the equivalent of 2 LD50's of sodium fluoracetate, zinc phosphide or fluoracetamide. Feeding ceased soonest in the case of sodium fluroacetate. Zinc phosphide gave very variable results, but it is thought that if wild rats had been used, feeding would have stopped nearly as soon as with sodium fluoracetate.4. It is considered that field trials to compare the efficiency of 1% flouracetamide and 2·5% zinc phosphide, both with ‘prebaiting’, would be well justified.5. Fluoracetamide at 2% may also prove to be a good alternative to 0·25% sodium fluoracetate as a ‘direct’ poison for controlling rats in sewers.We are indebted to Miss Y. Larthe and Miss E. J. Taylor who took part in the bioassay and in one of the experiments with the marked rats.

EFFECT OF 3-(4-CHLOROPHENYL)-1,1-DIMETHYLUREA ON DRY MATTER PRODUCTION, TRANSPIRATION, AND ROOT EXTENSION

Extension growth of the chlorophyll-containing roots of Hydrocharis morsusranae was inhibited by 0.5 p.p.m. of 3-(4-chlorophenyl)-1,1-dimethylurea (monuron) whereas concentrations close to the water saturation point of 230 p.p.m. were required to inhibit extension growth of the non-chlorophyll-containing attached roots of Zea mays and Phleum pratense and the detached roots of Pisum sativum.A total of 15–20 μg of monuron per gram fresh leaf applied through the cut petiole of detached primary leaves of Phaseolus vulgaris inhibited the increase of dry matter by 90% and suppressed transpiration 40–50%. Internal concentrations of 1–2 μg/g of monuron produced simultaneous enhancement of dry matter increase and of transpiration but concentrations of 5–10 μg/g produced a suppression of dry matter increase concurrently with an enhancement of transpiration. Age of leaf and the time of year in which the plants were grown altered the critical internal concentration levels required to affect dry matter increase and transpiration.Analysis of detached leaves treated with 15–20 μg/g monuron indicated a marked suppression of the formation of non-water-soluble carbohydrate, a slight suppression of the formation of water-soluble nitrogen, but little or no effect on water-soluble carbohydrate or on non-water-soluble nitrogen.In detached leaves o-phenanthroline, 3-phenyl-1,1-dimethylurea, and 3-(3,4-dichlorophenyl)-1,1-dimethylurea resembled monuron closely in symptom development and in their effect on dry matter production and transpiration. Iodoacetamide, 2,4-dinitrophenol, and 8-hydroxyquinoline each produced some effects similar to monuron but differed from it in certain respects; Thiourea, sodium diethyldithiocarbamate, sodium fluoracetate, ethyl-NN-diphenylcarbamate, and hydroxylamine hydrochloride were without noticeable effect.

Demographic Responses of Two House Mouse Populations to Moderate Suppression Measures with 1080 Rodenticide

Poisoning procedures used in mouse control operations often suppress an infestation without eliminating it; after an initial decline, the population apparently becomes more or less stabilized at a lower level. The mechanisms which underly this adjustment hold considerable interest for both the population ecologist and the pest control operator. During 1948 and 1949 an attempt was made to analyze the responses of a natural infestation of house mice (Mus i'nuschtds) to the withdrawal of poison after a period of 33 months in which professional control operations with 1080 (sodium fluoracetate) rodenticide had consistently failed to provide more than what was considered moderate control. This study (population A) was supplemented with another study (population B), made concurrently, in which population changes were analyzed as poisoning procedures were instituted. In both cases measurements were made of population size, mortality rates, life expectancy, population composition, breeding activity, local movements, trap susceptibility and poison susceptibility. Reports on the latter three aspects of the study have already been published (Young, Strecker and Emlen, 1950; Young, Neess and Emlen, 1952; Emlen and Crow, 1951). Data were collected over a period of eight months from September 28, 1948 to June 1, 1949. The first four mi-onths provided information on conditions before poison was removed in population A and before it was introduced in population B. The second four months provided 'the data for evaluation of the changes induced by poison withdrawal and poison introduction. The studies were made in two old vivarium buildings at the University of Wisconsin in Madi3on. Both buildings contained much natural mouse marborage and an abundant supply of food, provided for the experimental animals such as rabbits, doves, and chickens, but constantly available to the wild mice. Both buildings were maintained at room temperatures and were dark at night. Both were reasonably isolated from other mouse infested buildings, and their populations were thus essentially unaffected by ingress and egress. Traps set in large numbers in neighboring buildings captured over 500 mice, of which only 2 were marked animals from the populations under study. Sodium fluoracetate is a highly toxic and essentially tasteless rodenticide giving excellent results in laboratory tests (Anon., 1952). Field tests on house mice may give complete kills under optimum conditions; but populuations often persist, especially where bait are inadequately distributed as in the present instance (EEmlen, 1950). The poisoning procedure followed in this study used a one percent water solution distributed in one pint chicken drinking-wells, permanently maintained and refilled once each month. There were 18 wells or stations in building A, an average of one every 722 square feet of floor, and 8 in building B, an average of one every 622 square feet. Stations were distributed primarily in accordance with evidence of mouse activity, but no point in either building was more than 25 feet from a poison source. Population data were obtained by three sampling techniques: (1) live traps were maintained in both buildings and operated three consecutive nights each week throughout the eight months of the study. A total of 1781 mice was thus captured, toe-clipped for subsequent identification, and released. By using combinations of toe-clippings on both front feet and hind feet each mouse received a distinctive marking usable for individual identification on recapture or recovery. (2) Dead mice (eventually totalling 514) found near the poison and elsewhere were collected and examined at each visit. (3) In each of the two buildings, the study was terminated with an intensive snap-trapping campaign carried on over a fifteen day period until capture rates had declined to near zero. A total of nearly 900 mice from this source was available for autopsy. These sampling techniques rarely took any nestlings or young weanlings. The figures and indices to be presented are thus applicable only to the adult segment of the populations. ' Contribution from the University of Wisconsin, Department of Zoology. This work was supported in part by the University of Wisconsin Research Committee from funds supplied by the Wisconsin Alumni Research Foundation, and in part by a grant-in-aid from the National Institutes of Health. 2 Zoology Department, University of Wisconsin, Madison, Wisconsin. 3 Biology Department, Wisconsin State College, LaCrosse, Wisconsin. 'Zoology Department, Miami University, Oxford, Ohio.

PROTHROMBIN DEPRESSANTS AND SODIUM FLUORACETATE IN RAT CONTROL

Medical Journal of AustraliaVolume 2, Issue 21 p. 777-777 Correspondence PROTHROMBIN DEPRESSANTS AND SODIUM FLUORACETATE IN RAT CONTROL First published: 01 November 1957 https://doi.org/10.5694/j.1326-5377.1957.tb60319.xCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume2, Issue21November 1957Pages 777-777 RelatedInformation

Some experiments on the lethal dose of Sodium fluoracetate for the vole and the methods of application in the field as the poisoned baits

Some experiments on the lethal dose of Sodium fluoracetate for the vole and the methods of application in the field as the poisoned baits

On the effects of control of field mice by poisoned baits of Sodium fluoracetate in Hokkaido

On the effects of control of field mice by poisoned baits of Sodium fluoracetate in Hokkaido

Sodium fluoracetate (1080) as a rat poison

1. Sodium fluoracetate (1080) has been tested in the field as a poison for Rattus norvegicus and R. rattus.2. Direct poisoning (without Prebaiting) was used in thirteen tests on R. norvegicus. In eight of these tests censuses showed kills of at least 89% in three tests the poison failed, and in two the results were equivocal.3. Of three similar tests against R. rattus two were successful and one was a failure.4. Six tests of 1080 after prebaiting gave five successes (including one against R. rattus), and one in which the estimated kill was about 82%.5. In five out of six tests populations of R. norvegicus which had survived baiting with 1080 showed shyness (refusal) of the poison when it was given in a new bait base.6. The LD 50 of 1080 for a strain of white rats was found to be 3·8 mg./kg. (approx. range 2·8–5·2).7. A number of wild brids and some domestic animals were accidentally killed during the tests despite stringent precautions taken in laying the bait and in warning occupiers.8. It is concluded that: (a) although 1080 is probably more effective in direct poisoning than other poisons used in the past, it does not give as consistent results as the standard poisons do after prebaiting; (b) 1080 is too dangerous for general use.