The search for biomarkers of facial eczema, following a sporidesmin challenge in dairy cows, using mass spectrometry and nuclear magnetic resonance of serum, urine, and milk : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Sciences at Massey University, Palmerston North, Manawatu, New Zealand

Facial eczema (FE) is a secondary photosensitisation disease of ruminants that is significant in terms of both its economic importance to New Zealand and its impact on animal welfare. The clinical photosensitivity signs, caused by the retention of phytoporphyrin, occur secondarily to hepatobiliary damage caused by the mycotoxin sporidesmin. Currently it is difficult to diagnose subclinical animals and those in the early stages of the disease. The project was aimed at applying new analytical and statistical techniques, to attempt the early diagnosis of FE in dairy cows following the administration of a single oral dose (0.24 mg/kg) of sporidesmin. Well-established traditional techniques including production parameters, liver enzyme (GGT, GDH) activity measurements, as well as measurements of phytoporphyrin by fluorescence spectroscopy were made for comparison. Serum, urine, and milk were analysed using 1H Nuclear Magnetic Resonance (NMR), multivariate analysis (MVA), and time series statistics. Urine and milk did not prove useful for identification of sporidesmin intoxication. Serum metabolites differed between treated cows before and after administration of the toxin, and could distinguish samples belonging to the clinical group. The metabolites that were identified as being relevant to this classification were a mixture of glycoproteins, carboxylic acids, ketone bodies, amino-acids, glutamate, and glycerol, which were elevated for treated cattle, and acetate, choline, isoleucine, trimethylamine N-oxide, lipids, lipoproteins, cholesterol, and -glucose, which showed decreased concentrations. Citrate was found to be at higher concentration in non-responders and subclinicals only. When serum was analysed using ultra performance liquid chromatography electrospray ionisation mass spectrometry (UPLC/ESI-MS) and UPLC tandem MS (MS/MS), only samples from clinical cows could be discriminated. The molecular ions involved could be tentatively identified as a combination of taurine- and glycine-conjugated bile acids. These bile acids all became elevated. This study confirmed that liver enzyme activities (GGT, GDH) and phytoporphyrin concentrations are not effective as markers of early stage sporidesmin damage. Additionally, the new techniques were unable to detect early stage FE. However, some markers of treated cows were identified. The research does provide a strong foundation for future applications of metabolomics analysis, with MVA and time series statistics, for early stage FE diagnosis

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Hepatotoxicity of Two Progoitrin-Derived Nitriles in New Zealand White Rabbits

Cattle occasionally develop brassica-associated liver disease (BALD) and photosensitisation when grazing turnip or swede (Brassica spp.) forage crops. The liver toxin in these brassica varieties has yet to be discovered. Progoitrin is the dominant glucosinolate in incriminated crops. Apart from goitrin, progoitrin hydrolysis yields the nitrile, 1-cyano-2-hydroxy-3-butene (CHB), and the epithionitrile, 1-cyano-2-hydroxy-3,4-epithiobutane (CHEB). The two compounds were custom-synthesised. In a small pilot trial, New Zealand White rabbits were given either CHB or CHEB by gavage. Single doses of 0.75 mmol/kg of CHB or 0.25 mmol/kg of CHEB were subtoxic and elicited subclinical effects. Higher doses were severely hepatotoxic, causing periportal to massive hepatic necrosis associated with markedly elevated serum liver biomarkers often resulting in severe illness or death within 24 h. The possibility that one or both of these hepatotoxic nitriles causes BALD in cattle requires further investigation