https://ogma.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:38528 Wed 27 Oct 2021 16:09:11 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:45245 Daboia russelii) venom causes a range of clinical effects in humans. Hypotension is an uncommon but severe complication of Russell’s viper envenoming. The mechanism(s) responsible for this effect are unclear. In this study, we examined the cardiovascular effects of Sri Lankan D. russelii venom in anaesthetised rats and in isolated mesenteric arteries. D. russelii venom (100 µg/kg, i.v.) caused a 45 ± 8% decrease in blood pressure within 10 min of administration in anaesthetised (100 µg/kg ketamine/xylazine 10:1 ratio, i.p.) rats. Venom (1 ng/mL–1 µg/mL) caused concentration-dependent relaxation (EC₅₀ = 145.4 ± 63.6 ng/mL, R_max = 92 ± 2%) in U46619 pre-contracted rat small mesenteric arteries mounted in a myograph. Vasorelaxant potency of venom was unchanged in the presence of the nitric oxide synthase inhibitor, L-NAME (100 µM), or removal of the endothelium. In the presence of high K⁺ (30 mM), the vasorelaxant response to venom was abolished. Similarly, blocking voltage-dependent (K_v: 4-aminopryidine; 1000 µM) and Ca²⁺-activated (K_Ca: tetraethylammonium (TEA; 1000 µM); SK_Ca: apamin (0.1 µM); IK_Ca: TRAM-34 (1 µM); BK_Ca; iberiotoxin (0.1 µM)) K⁺ channels markedly attenuated venom-induced relaxation. Responses were unchanged in the presence of the ATP-sensitive K⁺ channel blocker glibenclamide (10 µM), or H1 receptor antagonist, mepyramine (0.1 µM). Venom-induced vasorelaxtion was also markedly decreased in the presence of the transient receptor potential cation channel subfamily V member 4 (TRPV4) antagonist, RN-1734 (10 µM). In conclusion, D. russelii-venom-induced hypotension in rodents may be due to activation of K_v and K_Ca channels, leading to vasorelaxation predominantly via an endothelium-independent mechanism. Further investigation is required to identify the toxin(s) responsible for this effect.]]> Wed 26 Oct 2022 19:42:29 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:50481  1,000 U/L). The Australian Toxicology Monitoring (ATOM) study is a prospective observational study, recruiting via two poison information centers and four toxicology units. Patients following an acute APAP ingestion presenting < 24 hours post-ingestion were recruited. Initial samples were analyzed for APAP metabolites, those measured were the nontoxic glucuronide (APAP-Glu) and sulfate (APAP-Sul) conjugates and NAPQI (toxic metabolite) conjugates APAP-cysteine (APAP-Cys) and APAP-mercapturate (APAP-Mer). The primary outcome was hepatotoxicity. In this study, 200 patients were included, with a median ingested dose of 20 g, 191 received acetylcysteine at median time of 5.8 hours post-ingestion. Twenty-six patients developed hepatotoxicity, one had hepatotoxicity on arrival (excluded from analysis). Those who developed hepatotoxicity had significantly higher total CYP metabolite concentrations: (36.8 μmol/L interquartile range (IQR): 27.8-51.7 vs. 10.8 μmol/L IQR: 6.9-19.5) and these were a greater proportion of total metabolites (5.4%, IQR: 3.8-7.7) vs. 1.7%, IQR: 1.3-2.6, P < 0.001)]. Furthermore, those who developed hepatotoxicity had lower APAP-Sul concentrations (49.1 μmol/L, IQR: 24.7-72.2 vs. 78.7 μmol/L, IQR: 53.6-116.4) and lower percentage of APAP-Sul (6.3%, IQR: 4.6-10.9 vs. 13.1%, IQR, 9.1-20.8, P < 0.001)]. This study found that those who developed hepatotoxicity had higher APAP metabolites derived from CYP pathway and lower sulfation metabolite on presentation. APAP metabolites may be utilized in the future to identify patients who could benefit from increased acetylcysteine or newer adjunct or research therapies.]]> Wed 26 Jul 2023 18:22:28 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30916 torsades de pointes. We investigated the QT interval in patients treated with methadone or buprenorphine using continuous 12-lead Holter recordings. Methods: We prospectively made 24-h Holter recordings in patients prescribed methadone or buprenorphine, compared to controls. After their normal dose a continuous 12-lead Holter recorder was attached for 24 h. Digital electrocardiograms were extracted hourly from the Holter recordings. The QT interval was measured automatically (H-scribe software, Mortara Pty Ltd) and checked manually. The QT interval was plotted against heart rate (HR) on the QT nomogram to determine abnormality. Demographics, dosing, medical history and laboratory investigations were recorded. Results: There were 58 patients (19 methadone, 20 buprenorphine and 19 control); median age 35 years (20–56 years); 33 males. Baseline characteristics were similar. Median dose of methadone was 110 mg day^–1 (70–170 mg day^–1) and buprenorphine was 16 mg day^–1 (12–32 mg day^–1). Seven participants had abnormal QT intervals. There was a significant difference in the proportion of prescribed methadone with abnormal QT intervals, 7/19 (37%; 95% confidence interval: 17–61%), compared to controls 0/19 (0%; 95% confidence interval: 0–21%; P = 0.008), but no difference between buprenorphine and controls (0/20). QT vs. HR plots showed patients prescribed methadone had higher QT-HR pairs over 24 h compared to controls. There was no difference in dose for patients prescribed methadone with abnormal QT intervals and those without. Conclusions: Methadone is associated with prolonged QT intervals, but there was no association with dose. Buprenorphine did not prolong the QT interval. Twenty four-hour Holter recordings using the QT nomogram is a feasible method to assess the QT interval in patients prescribed methadone.]]> Wed 11 Apr 2018 15:34:23 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30917 Wed 11 Apr 2018 13:49:58 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:45649 1,000 U/L), an adduct concentration ≥1.0 nmol/ml is sensitive and specific for identifying cases secondary to acetaminophen. Our aim was to characterise acetaminophen-protein adduct concentrations in patients following acetaminophen overdose and determine if they predict toxicity. Methods: We performed a multicentre prospective observational study, recruiting patients 14 years of age or older with acetaminophen overdose regardless of intent or formulation. Three serum samples were obtained within the first 24 h of presentation and analysed for acetaminophen-protein adducts. Acetaminophen-protein adduct concentrations were compared to ALT and other indicators of toxicity. Results: Of the 240 patients who participated, 204 (85%) presented following acute ingestions, with a median ingested dose of 20 g (IQR 10–40), and 228 (95%) were treated with intravenous acetylcysteine at a median time of 6 h (IQR 3.5–10.5) post-ingestion. Thirty-six (15%) patients developed hepatotoxicity, of whom 22 had an ALT ≤1,000 U/L at the time of initial acetaminophen-protein adduct measurement. Those who developed hepatotoxicity had a higher initial acetaminophen-protein adduct concentration compared to those who did not, 1.63 nmol/ml (IQR 0.76–2.02, n = 22) vs. 0.26 nmol/ml (IQR 0.15–0.41; n = 204; p <0.0001), respectively. The AUROC for hepatotoxicity was 0.98 (95% CI 0.96–1.00; n = 226; p <0.0001) with acetaminophen-protein adduct concentration and 0.89 (95% CI 0.82–0.96; n = 219; p <0.0001) with ALT. An acetaminophen-protein adduct concentration of 0.58 nmol/ml was 100% sensitive and 91% specific for identifying patients with an initial ALT ≤1,000 U/L who would develop hepatotoxicity. Adding acetaminophen-protein adduct concentrations to risk prediction models improved prediction of hepatotoxicity to a level similar to that obtained by more complex models. Conclusion: Acetaminophen-protein adduct concentration on presentation predicted which patients with acetaminophen overdose subsequently developed hepatotoxicity, regardless of time of ingestion. An adduct threshold of 0.58 nmol/L was required for optimal prediction. Lay summary: Acetaminophen poisoning is one of the most common causes of liver injury. This study examined a new biomarker of acetaminophen toxicity, which measures the amount of toxic metabolite exposure called acetaminophen-protein adduct. We found that those who developed liver injury had a higher initial level of acetaminophen-protein adducts than those who did not. Clinical Trial registration: Australian Toxicology Monitoring (ATOM) Study–Australian Paracetamol Project: ACTRN12612001240831 (ANZCTR) Date of registration: 23/11/2012.]]> Thu 23 Mar 2023 13:56:06 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28591 Sat 24 Mar 2018 07:37:29 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28154 Denisonia maculata) using enzyme immunoassays. Case: A 9-year old boy was bitten by an identified Ornamental Snake. He developed nausea, vomiting, local pain, and swelling. He had a leucocytosis (white cell count, 20.8 x 10⁹/L), an elevated international normalised ratio (INR) of 1.6, but otherwise normal blood tests including D-Dimer and activated partial thromboplastin time. He was treated with Australian Black Snake antivenom because the commercial venom detection kit was positive for Black snake. He was admitted for 36 h with continuing local pain and swelling requiring parenteral analgesia. Materials and methods: Blood samples were collected with informed consent for measurement of venom and antivenom concentrations. Venom-specific enzyme immunoassays were developed using the closely related D. devisi venom with Rabbit anti-Notechis (Tiger Snake) and anti-Tropidechis (Rough-scaled Snake) IgG antibodies to detect venom in serum. Standard curves for measured venom versus actual venom concentrations were made to interpolate Denisonia venom concentrations. In vitro procoagulant and anticoagulant activity of venom was assayed. Results: Denisonia venom was detected in the pre-antivenom sample as 9.6 ng/mL D. devisi venom. No antigenic venom components were detected in post-antivenom samples and there were high antivenom concentrations. D. devisi venom had mild in vitro procoagulant activity with a minimum concentration required to clot after 5 min of 2.5-5 μg/mL and even weaker anticoagulant activity. Conclusions: Denisonia bites appear to cause local effects and possibly mild systemic envenoming (with only non-specific systemic symptoms and leucocytosis), confirmed by detection of antigenic venom components in blood. A significant coagulopathy does not appear to occur.]]> Sat 24 Mar 2018 07:36:34 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28153 Sat 24 Mar 2018 07:36:34 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28152 Sat 24 Mar 2018 07:36:34 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29671 –1 provided a stable model and lowest objective function. This represents extremely rapid absorption with a half-life of 5 min. The final model had a clearance of 41.9 l h^–1 and volume of distribution of the central compartment of, 73.6 l. Median and interquartile range of initial (alpha) half-life was 0.32 h (0.26–0.37 h) and second (beta) half-life was 3.0 h (2.5–3.6 h). Simulations indicate that 10 mg alone provides an 80% probability of being above the lower limit of quantification (5 μg l^–1) for 7 h, 2 h longer than for 5 mg. Giving two 10 mg doses increased this duration to 10 h. Conclusions: Intramuscular droperidol is rapidly absorbed with high therapeutic concentrations after 5 and 10 mg doses, and supports clinical data in which droperidol sedates rapidly for up to 6 h.]]> Sat 24 Mar 2018 07:32:21 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40416 Oxyuranus scutellatus) envenoming causes life-threatening neuromuscular paralysis in humans. We studied the time period during which antivenom remains effective in preventing and arresting in vitro neuromuscular block caused by taipan venom and taipoxin. Venom showed predominant pre-synaptic neurotoxicity at 3 µg/mL and post-synaptic neurotoxicity at 10 µg/mL. Pre-synaptic neurotoxicity was prevented by addition of Australian polyvalent antivenom before the venom and taipoxin and, reversed when antivenom was added 5 min after venom and taipoxin. Antivenom only partially reversed the neurotoxicity when added 15 min after venom and had no significant effect when added 30 min after venom. In contrast, post-synaptic activity was fully reversed when antivenom was added 30 min after venom. The effect of antivenom on pre-synaptic neuromuscular block was reproduced by washing the bath at similar time intervals for 3 µg/mL, but not for 10 µg/mL. We found an approximate 10–15 min time window in which antivenom can prevent pre-synaptic neuromuscular block. This time window is likely to be longer in envenomed patients due to the delay in venom absorption. Similar effectiveness of antivenom and washing with 3 µg/mL venom suggests that antivenom most likely acts by neutralizing pre-synaptic toxins before they interfere with neurotransmission inside the motor nerve terminals.]]> Mon 11 Jul 2022 14:44:40 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40389 Oxyuranus scutellatus from four localities on the north-east coast of Australia, spanning a distance of 2000 km. The intra-specific variation in taipan venom was considerably less than the inter-specific variation between it and the other Australian elapids to which it was compared. The electrophoretic venom profile of O. scutellatus was visually different to six other genera of Australian elapids, but not to its congener inland taipan O. microlepidotus. There was minimal geographical variation in taipan venom, as the intra-population variation exceeded the inter-population variation for enzymatic activity, procoagulant activity, and the abundance of neurotoxins. The pre-synaptic neurotoxin (taipoxin) was more abundant than the post-synaptic neurotoxins (3FTx), with a median of 11.0% (interquartile range (IQR): 9.7% to 18.3%; range: 6.7% to 23.6%) vs. a median of 3.4% (IQR: 0.4% to 6.7%; range: 0% to 8.1%). Three taipan individuals almost completely lacked post-synaptic neurotoxins, which was not associated with geography and occurred within two populations. We found no evidence of sexual dimorphism in taipan venom. Our study provides a basis for evaluating the significance of intra-specific venom variation within a phylogenetic context by comparing it to the inter-specific and inter-generic variation. The considerable intra-population variation we observed supports the use of several unpooled individuals from each population when making inter-specific comparisons.]]> Mon 11 Jul 2022 11:21:41 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:44173 Mon 10 Oct 2022 10:13:31 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:41233 Fri 29 Jul 2022 14:02:23 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49420 Fri 12 May 2023 15:02:39 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49393 Fri 12 May 2023 14:34:18 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:46087 Fri 11 Nov 2022 09:17:07 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:45713 Fri 04 Nov 2022 10:27:59 AEDT ]]>