ORCID Profile
0000-0002-9495-9508
Current Organisation
Eastern Health
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Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.PBB.2013.07.002
Abstract: The interconnections between the serotonin and oxytocin pathways in the brain suggest that changes in oxytocin levels - arising from natural or drug-induced stimuli - lead to measureable changes in mood. In this paper, we review our findings in the context of what is known about the roles of oxytocin and vasopressin in the expression of a range of behaviours. In our first set of studies we investigated whether stimulation of oxytocin and vasopressin receptors, via central or systemic drug administration, would produce behavioural changes indicative of anti-depressant or anxiolytic activity. In our second study we investigated whether oxytocin receptor activation might be implicated in the interoceptive effects experienced with the popular party drug, MDMA ('ecstasy'). Our first study demonstrated that carbetocin, an oxytocin analogue, had anti-depressant actions following systemic and central administration, effects which were blocked by the oxytocin and vasopressin 1A receptor antagonist, atosiban. Carbetocin also had anxiolytic effects in the elevated plus maze. In an evaluation of the complementary nature of oxytocin and vasopressin, we found that systemic administration of desmopressin, a vasopressin analogue, was anxiogenic its effects blocked by atosiban which on its own produced robust anxiolytic behavioural changes. In our second study, we evaluated MDMA's interoceptive effects using a drug discrimination paradigm. Carbetocin partially substituted for MDMA, while atosiban interfered with MDMA discrimination, suggesting that oxytocin receptor activation contributes to MDMA-related interoceptive cues. The results of these and other clinical and preclinical studies suggest that oxytocin, as well as its closely related counterpart vasopressin, may provide alternative therapeutic targets for the treatment of mood disorders such as anxiety and depression. The possibility that oxytocin release may contribute to the perception of and processes underlying natural and drug-induced behavioural reinforcement offers exciting prospects for future study.
Publisher: Wiley
Date: 15-01-2021
DOI: 10.1111/NPH.17072
Abstract: The effects of plants on the biosphere, atmosphere and geosphere are key determinants of terrestrial ecosystem functioning. However, despite substantial progress made regarding plant belowground components, we are still only beginning to explore the complex relationships between root traits and functions. Drawing on the literature in plant physiology, ecophysiology, ecology, agronomy and soil science, we reviewed 24 aspects of plant and ecosystem functioning and their relationships with a number of root system traits, including aspects of architecture, physiology, morphology, anatomy, chemistry, biomechanics and biotic interactions. Based on this assessment, we critically evaluated the current strengths and gaps in our knowledge, and identify future research challenges in the field of root ecology. Most importantly, we found that belowground traits with the broadest importance in plant and ecosystem functioning are not those most commonly measured. Also, the estimation of trait relative importance for functioning requires us to consider a more comprehensive range of functionally relevant traits from a erse range of species, across environments and over time series. We also advocate that establishing causal hierarchical links among root traits will provide a hypothesis‐based framework to identify the most parsimonious sets of traits with the strongest links on functions, and to link genotypes to plant and ecosystem functioning.
Publisher: Wiley
Date: 30-03-2022
Abstract: Patients with borderline personality disorder (BPD) are likely to attend the ED while experiencing crises and associated self-injury and suicidality. Our study describes the prevalence, features, and outcomes associated with ED presentations by patients diagnosed with BPD in Outer Eastern Melbourne, Australia. A retrospective electronic audit of 157 364 ED attendances identified 700 unique BPD-related ED presentations between May 2015 and April 2016. For the purpose of comparison, 583 (81% female) of these 700 cases were matched with 'depression only' cases. ED re-presentation data were also extracted. The 583 matched BPD patients attended ED a total of 2807 times during the audit year compared with 1092 attendances for matched depression-only patients. BPD patients were more likely to: arrive by ambulance (50%) have comorbid substance abuse (44%) have a psychotic (15%) or bipolar disorder (17%) be under the care of a psychiatrist (31%) be case-managed (42%) and be admitted to an inpatient unit (21%). ED doctors saw 38% of BPD or depression patients within the recommended time according to their triage category. The majority (73%) of BPD patients attended ED more than once during the audit year (average 4.81 ± 6.63 times range 2-78). Repeated ED attendance of a subset of patients diagnosed with BPD highlights both the severity of their presentation and the inadequacy of community mental health services for meeting their complex needs. Development of effective ED referral pathways with follow-up to engage patients in BPD-appropriate treatment will reduce the likelihood of crises and reliance on hospital EDs for acute episodic care.
Publisher: Wiley
Date: 05-10-2021
DOI: 10.1111/NPH.17572
Abstract: In the context of a recent massive increase in research on plant root functions and their impact on the environment, root ecologists currently face many important challenges to keep on generating cutting‐edge, meaningful and integrated knowledge. Consideration of the below‐ground components in plant and ecosystem studies has been consistently called for in recent decades, but methodology is disparate and sometimes inappropriate. This handbook, based on the collective effort of a large team of experts, will improve trait comparisons across studies and integration of information across databases by providing standardised methods and controlled vocabularies. It is meant to be used not only as starting point by students and scientists who desire working on below‐ground ecosystems, but also by experts for consolidating and broadening their views on multiple aspects of root ecology. Beyond the classical compilation of measurement protocols, we have synthesised recommendations from the literature to provide key background knowledge useful for: (1) defining below‐ground plant entities and giving keys for their meaningful dissection, classification and naming beyond the classical fine‐root vs coarse‐root approach (2) considering the specificity of root research to produce sound laboratory and field data (3) describing typical, but overlooked steps for studying roots (e.g. root handling, cleaning and storage) and (4) gathering metadata necessary for the interpretation of results and their reuse. Most importantly, all root traits have been introduced with some degree of ecological context that will be a foundation for understanding their ecological meaning, their typical use and uncertainties, and some methodological and conceptual perspectives for future research. Considering all of this, we urge readers not to solely extract protocol recommendations for trait measurements from this work, but to take a moment to read and reflect on the extensive information contained in this broader guide to root ecology, including sections I–VII and the many introductions to each section and root trait description. Finally, it is critical to understand that a major aim of this guide is to help break down barriers between the many subdisciplines of root ecology and ecophysiology, broaden researchers’ views on the multiple aspects of root study and create favourable conditions for the inception of comprehensive experiments on the role of roots in plant and ecosystem functioning.
Publisher: SAGE Publications
Date: 18-06-2009
Abstract: Abstract Despite evidence that ±3,4-methylenedioxymeth hetamine (MDMA ‘ecstasy’) causes persistent alterations to the serotonergic system of animals, evidence for long-term neurological effects of ecstasy/MDMA in humans remains equivocal. The current study assessed serotonin functioning of nine male and 11 female recreational ecstasy polydrug users by measuring neuroendocrine (prolactin, cortisol) responses to pharmacological challenge with the selective serotonin reuptake inhibitor citalopram, compared with nine male and five female cannabis polydrug users and 11 male and 11 female non-drug using controls. A single-blind, randomised, placebo-controlled design was used. Subjective responses, other substance use, mood, personality traits and demographic variables were measured to control for potentially confounding variables. There were no significant differences between ecstasy polydrug users, cannabis polydrug users and non-drug using controls in neuroendocrine or subjective responses to serotonergic challenge, and there were no sex by drug group interactions. There was no relationship between extent of ecstasy use and neuroendocrine functioning, alone or in combination with potential confounding variables. Subjective responses to the pharmacological challenge (nausea, tremor, dry mouth), novelty seeking and lifetime dose of alcohol were the only variables that contributed to one or more of the neuroendocrine outcome variables. These data do not support the premise that recreational ecstasy/MDMA use results in measurable impairment of serotonergic control of endocrine activity.
No related grants have been discovered for Peter Ryser.