A retrospective study of cane toad (Rhinella marina) toxicity in 190 domestic cats in Southeastern Queensland: Clinical presentations, treatments, and outcomes.

OBJECTIVE: To report the clinical presentations, treatments and outcomes of toad toxicity in domestic cats in Southeastern Queensland, Australia. METHODS: This report describes a retrospective study of 190 cases of cane toad (Rhinella marina) toxicity in cats in south-eastern Queensland, Australia. All cases were presented for veterinary treatment between 2011 and 2020 at four specialist veterinary emergency centres in Southeast Queensland, Australia. Cane toad toxicity was diagnosed based on a history of exposure and clinical signs. RESULTS: Domestic short-hair breeds accounted for 53.6% of the cases. Presentation was seasonal with the highest incidence over the warmer months of the year (November - March). Hypersalivation was described in 96.3% (183/190), tachypnoea in 34.2% (65/190) and altered behaviour in 18.4% (35/190) of cases. Seizures occurred in 1% of cases. Of the 190 cases, 6.3% (12/190) were hospitalised and 0.5% (1/190) were euthanised and overall 99.5% (189/190) survived hospital discharge. CLINICAL SIGNIFICANCE: Cane toad toxicity is relatively common in cats in Southeast Queensland and following buccal lavage the prognosis for recovery was excellent.

Tick paralysis in dogs and cats in Australia: treatment and prevention deliverables from 100 years of research.

This review of tick paralysis caused by Ixodes holocyclus in Australia addresses the question: What are the key discoveries that have enabled effective treatment and prevention of tick paralysis in dogs and cats? Critical examination of 100 years of literature reveals that arguably only three achievements have advanced treatment and prevention of tick paralysis in animals. First, the most significant treatment advance was the commercial availability of tick antiserum in the 1930s. Hyperimmune serum currently remains the only specific anti-paralysis tick therapy available to veterinarians in Australia. Second, advances in veterinary critical care have increased survival rates of the most severely affected dogs and cats. Critical care advancements have been enabled through specialised veterinary hospitals that can provide appropriate care 24 h a day, and advanced training of veterinarians, veterinary nurses and technicians. Third, perhaps that biggest advance of all in the last 100 years of research has been the commercial availability of the isooxazoline class of acaricidal preventatives in Australia specifically for I. holocyclus. This highly effective class of preventatives offers long duration of action, low cost, spot-on or oral formulations and a low rate of adverse reactions. Animal owners and veterinarians now have the most useful tool of all - a reliable preventative. This review reveals the key events in research over the last 100 years and the tortuous pathway to delivering better treatment and preventative options for this enigmatic Australian parasite.

Progesterone binding to hen oviduct genome: specific versus nonspecific binding.

Data are presented to explain discrepancies in the literature involving the in vitro binding of steroid receptor complexes to isolated nuclei and chromatin. The type of binding in vitro of the progesterone-receptor complex to nuclei, chromatin, or DNA of hen organs is largely determined by the ionic strength of the medium. Low ionic conditions (0.01 to 0.05 molar potassium chloride) result in a nonspecific, nonsaturable binding, while high ionic conditions (0.15 to 0.20 molar potassium chloride) create a tissue-specific, saturable binding. Pure DNA binds the steroid receptor complex extensively in low salt but very little in the higher salt conditions.

Separation and characterization of transcriptionally active and inactive nuclear subfractions of AKR mouse embryo cells.

This study was initiated with the objective of separating and characterizing two or more nuclear subfractions, which could then be compared with respect to their relative propensity for binding carcinogenic polycyclic aromatic hydrocarbons. Nuclei were isolated from cloned AKR-2B mouse embryo cells, which are susceptible to transformation by chemical carcinogens. The nuclei were mechanically sheared and subfractions were separated by sedimentation through a 0.17 to 1.7 M sucrose gradient. When the cells were treated with [3H]uridine for 30 min, most of the label incorporated into RNA was recovered in the top region of the gradients, which represented Nuclear Subfraction I. The majority of the chromatin DNA, however was localized in the bottom region (Subfraction II) and the pellet (Subfraction III). Precipitation (with CaCl2) of the rapidly labeled RNA of Subfraction I along with the chromatin DNA suggested that the label was present in nascent RNA chains still attached to the chromatin. Thus, the transcripitionally active chromatin seemed to be localized in Nuclear Subfraction I. The chromatin of Subfraction I was also the best template for RNA synthesis in vitro with exogenous bacterial polymerase. The protein and RNA content of subfraction I was greater than that of the other two subfractions and whole chromatin. Electron microscopy revealed the presence of membrane material in Subfraction I and II, with little such material in Subfraction III. Subfraction I differed from Subfractions II and II and whole chromation with respect to thermal denaturation of the DNA and histone composition (as determined by gel electrophoresis). The acidic protein composition (as determined by gel electrophoresis) differed for the chromatin of all three nuclear subfractions.

Binding of polycyclic aromatic hydrocarbons to transcriptionally active nuclear subfractions of AKR mouse embryo cells.

The objective of this study was to examine the binding of carcinogenic polycyclic aromatic hydrocarbons in well-characterized nuclear subfractions from transformable cells in culture. A cloned line of AKR mouse embryo cells was exposed to culture medium containing [3H]-3-methyl-cholanthrene (MC) (0.4 mug/ml) 670 Ci/mole). Cellular uptake and nuclear binding were determined after 4 hr of exposure. The addition of unlabeled MC up to 10 mug/ml did not cause reduction of [3H]MC cellular uptake or nuclear binding. From 2 to 5% of the total cellular MC was localized in the nuclei. All nuclear subfractions obtained from mechanically sheared nuclei and separated on sucrose gradients showed some MC binding; however, a high-affinity, high-specific-activity binding of MC was associated only with the slower-sedimenting component shown to represent that fraction of nuclear chromatin that is transcriptionally active. Conditions that caused the precipitation of this chromatin also resulted in the precipitation of the radioactive compound, thus suggesting that the MC was physically bound to the chromatin. Unlabeled MC (10 mug/ml) saturated this high-affinity MC binding to the transcripitionally active chromatin but did not saturate the binding to the other nuclear fractions. The binding of another potent carcinogen, [3H]-1,2,5,6-dibenzanthracene, and the "weak" carcinogen, [3H]-1,2,3,4-dibenzanthracene (3,4-DBA), to whole nuclei and nuclear subfractions was also determined. The concentration, specific activity, and time of treatment were identical with those used for MC. The level of binding of [3H]-1,2,5,6-dibenzanthracene was approximately 3-fold greater in whole nuclei on a per mass DNA basis than in those of either the MC or the 3,4-DBA. The binding of MC and 3,4-DBA to whole nuclei was approximately equal. As with MC, the [3H]-1,2,5,6-dibenzanthracene demonstrated a peak of high specific activity binding to the slower-sedimenting fraction of chromatin while the 3,4-DBA displayed considerably less binding to this fraction.

NT-proBNP and cardiac troponin I concentrations in dogs with tick paralysis caused by Ixodes holocyclus.

OBJECTIVE: The purpose of this study was to determine through measurement of cardiac biomarkers whether there was cardiac involvement in dogs infested with Ixodes holocyclus. METHODS: Dogs with tick paralysis and no-mild (group 1; n = 44) or moderate-severe respiratory compromise (group 2; n = 36) and a control group of dogs (n = 31) were enrolled. Plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP), serum cardiac troponin I (cTnI) and serum creatinine concentrations were determined. For most of the affected dogs SpO2 was determined. RESULTS: SpO2 readings did not differ between groups 1 and 2. Three animals in group 2 had an SpO2 reading <90%. NT-proBNP concentrations were lower in both groups 1 and 2 compared with the control group. There was no difference in cTnI concentrations among groups, although they were elevated in four dogs, including the three dogs in group 2 with SpO2 readings <90%. Creatinine concentrations were within the reference interval for all dogs, but did differ among the groups, with control dogs having the highest values, followed by group 1 and then group 2. CONCLUSION: This study did not detect significant cardiac involvement in dogs with tick paralysis induced by I. holocyclus. Evidence for reduced preload in dogs with tick paralysis was provided by lower NT-proBNP concentrations compared with control dogs. Severe hypoxaemia may not be a significant component of the clinical picture in many of the dogs presenting with tick paralysis. Dogs with severe hypoxaemia may have loss of cardiomyocyte integrity, reflected by elevated cTnI concentrations.

Isolation and characterization of the estrogen receptor in hen oviduct: evidence for two molecular species.

Isolation of the estrogen receptor was undertaken for comparison with the progesterone receptor with respect to seasonal variations in receptor level and function and the specificity of nuclear binding sites in the hen oviduct. The estrogen receptor in the chick and hen oviduct has been only partially characterized, with conflicting or incomplete information on its properties. We have isolated a binding protein and have partially purified it by ammonium sulfate precipitation. The binding protein displays a single, high affinity class of sites (Kd similar to 10(-10) M) with a low capacity (35 fmol/mg protein) for 17beta-estradiol, shows a marked specificity for estrogenic compound, and is tissue specific. The protein sediments at approximately 8S in low salt and at approximately 4S in high salt conditions. The protein elutes from molecular sieve chromatography (agarose-0.5 m) in high salt conditions (0.3 M KCI) in a molecular weight range of approximately 60,000. DEAE chromatography and isoelectric focusing suggest that there are two molecular species, one focusing at pH 6.8 and the other at pH 7.3. Estrogen complexed to this protein will bind to nuclear acceptor sites in a cell-free assay in which free estrogen, estrogen bound to serum proteins, and [3H]estradiol receptor exchanged with a 100-fold excess of cold estradiol do not bind. Binding to nuclei is saturable and displaceable by an excess of nonradioactive estrogen receptor complexes under conditions of constant protein concentration. The above results represent the most detailed characterization to date of the cytosol estrogen receptor of hen oviduct This is the first demonstration of saturable, receptor-dependent, cell-free binding to target organ nuclei.

Effect of compounds modulating amino acid neurotransmission on the development and control of bicuculline-induced epileptogenic spiking in the rat.

Dose-related EEG spiking was induced and monitored in urethane-anaesthetised rats by cortical superfusion of bicuculline methiodide, through a cortical cup incorporating recording electrodes. The total integrated spike voltage, total number of spikes as well as the average size of the spikes were monitored. Extracellular recording showed that each individual EEG spike coincided with the sudden, synchronous firing of a group of superficial cortical cells (layer II-III). gamma-Aminobutyric acid reduced both the size and frequency of the spikes, whilst muscimol and clonazepam mainly reduced the size of the spikes. (+/-) Baclofen reduced the frequency of the spikes, with no effect on their size. The NMDA receptor antagonists, AP5 and AP7 reduced spiking by attenuating size, with no effect on frequency. The NMDA channel blocker MK801 also reduced the size of the spikes but increased their frequency at large concentrations; increasing magnesium in the artificial CSF, from 1 to 10 mM, had a similar effect. Compounds believed to preferentially block non-NMDA receptors, GAMS and CNQX, reduced activity by mainly reducing the frequency of spikes. It is concluded that activation of non-NMDA and GABAB receptors are important for controlling the initiation of bicuculline-induced spikes and NMDA and GABAA receptors, for the control of their subsequent development.

The role of GABA and excitatory amino acids in the development of the leptazol-induced epileptogenic EEG.

The developing epileptogenic electroencephalogram (EEG), seen during the slow intravenous infusion of leptazol, is sensitive to various anticonvulsant drugs, particularly those known to augment the function of gamma-aminobutyric acid (GABA), such as clonazepam and sodium valproate, which specifically prolong the earlier wave-like (pre-spiking) phases. Thus, whilst antagonism of GABA may be responsible for spiking, the early wave-like phases may be due to GABA released in the cortex as a feedback control to delay spiking. Intravenous infusion of the GABA antagonists, bicuculline and picrotoxin, produced a developing EEG with spiking the first abnormal feature noted and no wave-like phase, like that seen with leptazol. Cortical superfusion of GABA during the infusion of leptazol, enhanced kand prolonged the wave-like phase, whilst bicuculline reduced it. Cortical superfusion of leptazol, picrotoxin or larger concentrations of bicuculline produced spiking but no wave-like activity. When leptazol and GABA were superfused together they produced wave-like activity similar to that seen during infusions of leptazol. Of the excitatory amino acid antagonists, only those active at receptors for N-methyl-D-aspartate (NMDA) influenced the EEG changes induced by leptazol. It is suggested that leptazol produces waves in the EEG by stimulating subcortical pathways to release GABA in the cortex and that spiking occurs as the cortex is further stimulated by GABA antagonism and the release of excitatory amino acids.

Isothiourea derivatives of 6-phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole with broad-spectrum anthelmintic activity.

A series of isothiourea derivatives of 6-phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole (tetramisole) is described. The compounds are prepared by the S-alkylation of the thioureas that were obtained either by the reaction of an amine with 6-(3-isothiocyanatophenyl)-2,3,5,6-tetrahydroimidazo[2,1-b] thiazole or by the reaction of an isothiocyanate with 6-(3-aminophenyl)-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole. These derivatives have an improved spectrum of activity over tetramisole and are active against nematodes, cestodes, and trematodes. The structure-activity relationships are discussed.

Synthesis and anthelmintic activity of a series of pyrazino[2,1-a][2]benzazepine derivatives.

A series of 1,2,3,4,6,7,8,12b-octahydropyrazino[2,1-alpha][2] benzazepine derivatives was prepared and the cestocidal activity of the compounds evaluated in an in vitro Taenia crassiceps screen. Many of these derivatives proved to be highly active, and 2-(cyclohexylcarbonyl)-4-oxo-1,2,3,4,6,7,8,12b- octahydropyrazino[2,1-alpha][2]benzazepine, epsiprantel (BAN) (22), was selected for further development. The structure-activity relationships are discussed.

Novel 1H-benzimidazol-4-ols with potent 5-lipoxygenase inhibitory activity.

The synthesis and structure--activity profile of 2-substituted benzimidazol-4-ols as inhibitors of cell-free RBL-1 5-lipoxygenase are discussed, and their potency is compared with that of the standard inhibitors phenidone, AA 861, BW 755C, and nordihydroguaiaretic acid. In contrast to the standard compounds, most did not inhibit the release of slow-reacting substance of anaphylaxis (SRS-A) in vivo when administered at 200 microM ip to rats subjected to peritoneal anaphylaxis, although five compounds containing a methoxylated benzyl group (compounds 36, 39, 42, and 43) or hydroxylated benzyl group (41) showed similar activity to that of phenidone, nordihydroguaiaretic acid, and AA 861. Of the many compounds tested, two, 5-tert-butyl-7-methyl-2-(trifluoromethyl)-1H-benzimidazol-4-ol (57) and 2-(4-methoxybenzyl)-7-methyl-1H-benzimidazol-4-ol (36), like dexamethasone, inhibited monocyte accumulation in a pleural exudate model of inflammation. Standard lipoxygenase inhibitors such as phenidone, BW 755C, and AA 861 were inactive in this system.

Release of [3H]noradrenaline from descending tracts in the cat spinal cord in vivo.

The release of [3H]noradrenaline into the perfused central canal of the cat lumbar-sacral spinal cord was monitored in vivo. Stimulation of descending tracts produced an increase efflux into artificial cerebrospinal fluid containing 10(-6) M phenoxybenzamine which could be dissociated from any concurrent rise in blood pressure. No release was produced by stimulating dorsal roots over the length of cord perfused. It appears, therefore, that noradrenaline can be released from descending nerve terminals, but not from dorsal root afferents in the spinal cord.

Effect of L-dopa alone and with benserazide on the spontaneous activity of striatal neurones in normal and 6-hydroxydopamine-lesioned rats.

1. The effects of L-dopa methylester (LDME), an analogue of levodopa, on the spontaneous activity of dopamine sensitive neurones in the rat striatum, after 6-hydroxydopamine induced degeneration of the nigrostriatal tract were compared with those in unlesioned animals both in the absence and presence of benserazide, a peripheral DOPA decarboxylase inhibitor (PDI). 2. Studies were performed at 5-7 days post lesion (group 1 animals), at 21 days (group 2) when denervation supersensitivity was evident by contralateral turning to apomorphine and at the same time but following 7 days dosing with LDME plus benserazide (group 3). 3. In unlesioned animals, LDME alone inhibited spontaneous firing by some 45% over 60 min including a marked but transient early phase which was still present in all lesioned animals even though the later inhibition was significantly reduced in group 1 and 3 animals. 4. When given after benserazide in unlesioned animals LDME still produced a similar level of overall inhibition but without the early phase. The lesion reduced the overall inhibition, except in group 2 animals, and after chronic dosing (group 3) it was almost absent. 5. It is proposed that since the early inhibition with LDME alone is still seen after lesion of the nigrostriatal tract but not after the PDI benserazide, it is caused by peripherally formed dopamine and that as the delayed inhibition with LDME alone and after benserazide are all reduced by nigrostriatal lesions, as is its amphetamine like ipsilateral turning, that this depends on locally (striatal) synthesized dopamine. 6. This study also shows the chronic levodopa/PDI treatment reduces the compensating increased activity of surviving dopaminergic neurones and the functional supersensitivity to dopamine and suggests that the long term administration of levodopa may reduce its own utilization and activity in the striatum and in the treatment of Parkinson's Disease [corrected].

Effects of 3-O-methyl on L-dopa-facilitated synthesis and efflux of dopamine from rat striatal slices.

1. The effect of L-dopa on the spontaneous and KCl-evoked efflux of dopamine from rat striatal slices, measured by high performance liquid chromatography (h.p.l.c.) with electrochemical detection (e.c.d.) was investigated in the absence and presence of 3-O-methyl dopa (OMD), an O-methylated metabolite of L-dopa. 2. The addition of exogenous L-dopa (10 microM) significantly increased both the spontaneous efflux of dopamine and that evoked by KCl. 3. In the presence of 50 microM OMD, the effects of L-dopa on the spontaneous and KCl-evoked efflux of dopamine were smaller but only the former was significantly different from that in the absence of OMD. However, the total efflux of dopamine during the overall superfusion time (70 min) including KCl depolarization was significantly lower than in the absence of OMD. 4. Analysis of tissue content after superfusion revealed that the levels of dopa and dopamine in slices superfused with L-dopa in the presence of OMD were significantly higher than those superfused with L-dopa alone. 5. The finding that OMD significantly reduced the efflux of dopamine whilst increasing its concentration in striatal slices after L-dopa superfusion could explain the reduced efficacy seen after long-term therapy with L-dopa and a peripheral dopa decarboxylase inhibitor in Parkinsonian patients when plasma and brain OMD are very high.

Tremor induced by tetrabenazine.

1. Acute administration of tetrabenazine produced tremor in cats, in doses which caused sedation but not hypothermia.2. The pattern of movements resembled shivering rather than Parkinsonism, and warming the skin suppressed the tremor.3. The tremor was not influenced by hyoscine.4. Tremor produced by amylobarbitone was essentially similar to that induced by tetrabenazine.

The evaluation of different types of anti-convulsant drug activity against leptazol-induced epileptogenic activity in the anaesthetized rat.

1 The effects of various anticonvulsant drugs were evaluated quantitatively on the development of the epileptogenic EEG, induced by the intravenous infusion of leptazol in rats anaesthetized with urethane. 2 Leptazol alone produced five distinct phases of EEG activity developing from early wave and small spike and wave activity to larger spikes which later grouped and led to full body convulsion (FBC). 3 Drugs effective in petit mal such as clonazepam (0.1 and 0.25 mg kg-1) and ethosuximide (100 and 200 mg kg-1), significantly delayed the time to FBC by prolonging the early phases of the epileptogenic EEG and delaying the appearance of spiking. 4 Drugs effective in grand mal such as sodium valproate (60 mg kg-1) and phenytoin (5 mg kg-1) significantly prolonged the time to FBC by extending the later phases of the EEG and the development and grouping of spikes. Higher doses of these compounds were without effect. Carbamazepine and phenobarbitone produced mixed effects but were generally not markedly anticonvulsant. 5 The model is sensitive to drugs effective in both petit mal and grand mal, and appears able to differentiate usefully between them.

Effect of tetrabenazine and alpha-methyl-m-tyrosine on exploratory activity and brain catecholamines in rats.

1. Spontaneous exploratory locomotor activity of Wistar rats was measured in photocell activity cages, and brain noradrenaline (NA) and dopamine (DA) were determined fluorometrically after ion exchange purification.2. Tetrabenazine (TBZ) (10 mg/kg) produced a fall in NA and DA concentrations in rat brain stems which was correlated with the fall in activity in female Wistar rats.3. alpha-Methyl-m-tyrosine (alphaMMT) reduced the concentration of rat brain NA without affecting DA concentration or activity.4. Pretreatment with alphaMMT did not stop TBZ from producing a marked reduction in activity and NA concentration, but partially protected DA from the depleting action of TBZ.5. These results support a role for catecholamines in the control of motor activity, but they do not implicate NA more than DA and they emphasize that the mechanism by which drugs affect the concentrations of catecholamines may be more important than the gross concentrations attained.

Importance of noradrenaline found in a functional pool in maintaining spontaneous locomotor activity in rats.

1. Spontaneous locomotor activity (activity) in male Wistar rats was compared with the concentrations of brain noradrenaline (NA), dopamine (DA) and metaraminol.2. alpha-Methyl-m-tyrosine (alphaMMT) (400 mg/kg) reduced the concentrations of DA as well as NA but activity remained high in the presence of metaraminol formed from the alphaMMT. When tetrabenazine (TBZ) was given after alphaMMT pretreatment there was a fall in the levels of activity and in the concentrations of NA, DA and metaraminol.3. alpha-Methyl-p-tyrosine (alphaMT) produced a fall in activity which was correlated with falls in the concentrations of NA and DA. 5-Hydroxytryptamine (5-HT) did not appear to be affected.4. After depletion of NA and DA by alphaMT and TBZ, administration of L-dopa produced a return in activity which was significantly correlated with the concentration of NA but not DA. When alphaMMT was given to a similar group of pretreated animals there was no recovery of activity despite high concentrations of DA and metaraminol.5. The dopamine beta hydroxylase inhibitor, diethyldithiocarbamate (DDC), suppressed activity as well as the concentrations of NA and DA at high doses (750 mg/kg) but smaller doses (400 mg/kg) plus L-dopa gave high DA concentrations without activity.6. It is concluded that NA and not DA is associated with activity but that it is only part of the total NA which is in the biosynthetic storage granule affected by drugs like alphaMT and TBZ, which controls activity. Drugs that do not affect this pool may lower NA concentrations but not reduce activity.7. The replacement of NA by metaraminol in this functional pool does not restore activity.

The effect of benserazide on the peripheral and central distribution and metabolism of levodopa after acute and chronic administration in the rat.

1. The effects of levodopa alone (50 mg kg-1) and levodopa (10 mg kg-1) plus benserazide (50 mg kg-1) were tested on the levels of dopa, dopamine, 3-methoxytyrosine (3-MT), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), measured by h.p.l.c. with electrochemical detection, in samples of plasma, CSF, urine, striatum and hypothalamus of rats taken 30 min after injection. Levodopa plus benserazide produced significantly higher levels of dopa in plasma and brain than levodopa alone and reduced the peripheral synthesis and metabolism of dopamine. 2. When given chronically over 6 weeks the advantages of adding benserazide (50 mg kg-1 day-1) to levodopa (40 mg kg-1 day-1) were less marked and although more dopamine was present in the striatum than with levodopa given alone (200 mg kg-1 day-1) there was no evidence of any increase in its metabolites (HVA and DOPAC) and therefore of its turnover and utilisation. 3. The most striking effect of chronic treatment with levodopa plus benserazide was the appearance of large quantities of 3-MT in plasma, CSF and brain. 4. When levodopa alone, or levodopa plus benserazide, was given as an acute challenge to animals receiving the same treatment chronically, it was found that levodopa alone still produced increases in striatal dopamine, DOPAC and HVA in those animals dosed chronically on levodopa, but it was less effective in this respect when given with benserazide to the animals dosed with levodopa plus benserazide. 5. It is concluded that this difference in levodopa distribution may depend on the persistence in benserazide-treated animals of 3-MT, which has a long half-life and may compete with dopa for transport into the blood and brain. 6. The implication of these findings to the treatment of Parkinsonism is discussed.