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Jahangir S, Khatua B, Smichi N, Rajalingamgari P, Pillai AN, Summers MJ, McFayden B, Kostenko S, Gades NM, Singh VP. Buprenorphine Affects the Initiation and Severity of Interleukin Induced Acute Pancreatitis in Mice. Am J Physiol Gastrointest Liver Physiol 2024. [PMID: 38651230 DOI: 10.1152/ajpgi.00083.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 04/19/2024] [Indexed: 04/25/2024]
Abstract
Acute pancreatitis (AP) is a common disease with no targeted therapy and has varied outcomes ranging from spontaneous resolution to being lethal. While typically painful, AP can also be painless. Various agents, including opioids are used for pain control in AP; the risks, and benefits of which are often debated. Since experimental AP in mice is used to study the efficacy of potential therapies, we studied the effect of a commonly used opioid buprenorphine on the initiation and progression of AP. For this we administered extended-release buprenorphine subcutaneously prior to inducing the previously established severe AP model that uses Interleukins 12 and 18 (IL12,18) in genetically obese (ob/ob) mice and compared this to mice with AP but without the drug. Mice were monitored over 3 days and parameters of AP induction and progression were compared. Buprenorphine significantly reduced the serum amylase, lipase, pancreatic necrosis, and AP associated fat necrosis which is ubiquitous in obese mice and humans. Buprenorphine delayed the AP associated reduction of carotid artery pulse distention, and development of hypothermia, hastened renal injury, and muted the early increase in respiratory rate vs. IL12,18 alone. The site of buprenorphine injection appeared erythematous, inflamed, and microscopically showed thinning, loss of epidermal layers which had increased apoptosis. In summary, subcutaneous extended-release buprenorphine interfered with the induction of AP by reducing serum amylase, lipase, pancreatic and fat necrosis, the worsening of AP by delaying hypotension, hypothermia, while hastening renal injury, respiratory depression, and causing cutaneous injury at the site of injection.
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Affiliation(s)
- Sarah Jahangir
- Department of Medicine, Mayo Clinic in Arizona, Scottsdale, AZ, United States
| | | | - Nabil Smichi
- Mayo Clinic in Arizona, Scottsdale, AZ, United States
| | | | | | - Megan J Summers
- Department of Medicine, Mayo Clinic in Arizona, Scottsdale, AZ, United States
| | - Bryce McFayden
- Department of Medicine, Mayo Clinic in Arizona, Scottsdale, AZ, United States
| | - Sergiy Kostenko
- Department of Medicine, Mayo Clinic in Arizona, Scottsdale, AZ, United States
| | - Naomi M Gades
- Department of Comparative Medicine, Mayo Clinic in Arizona, Scottsdale, AZ, United States
| | - Vijay P Singh
- Internal Medicine, Mayo Clinic in Arizona, Scottsdale, AZ, United States
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Stefanidis KB, Mieran T, Schiemer C, Freeman J, Truelove V, Summers MJ. Cognitive correlates of reduced driving performance in healthy older adults: A meta-analytic review. Accid Anal Prev 2023; 193:107337. [PMID: 37820426 DOI: 10.1016/j.aap.2023.107337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 06/11/2023] [Accepted: 10/03/2023] [Indexed: 10/13/2023]
Abstract
AIMS / OBJECTIVES This meta-analytic review examines the evidence for the relationship between cognitive function and driving performance in older adults. The primary aims of this review were: (a) to identify cognitive correlates of reduced driving performance in older adults and (b) to determine whether such measures reliably predict reductions in driving performance over time. METHODS This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Peer reviewed studies that examined the (cross-sectional or longitudinal) relationship between standardised neuropsychological test performance measures and driving performance (e.g., via an on-road test, in-vehicle monitoring system, hazard perception test or driving simulator) in healthy adults aged 60 years and older, were included. RESULTS/DISCUSSION Eighteen studies were eligible for inclusion, of which 12 met requirements for meta-analysis. The results indicated that reaction time and Trail Making Test (TMT) A scores exhibited small-to-moderate correlations with driving performance, with moderate effects identified for block design, TMT B, Useful Field of View (UFOV) 2 and 3 tests. Further, no significant relationships were observed between the Mini-Mental State Examination and UFOV 1 with driving performance. Due to a paucity of data, the longitudinal relationship between such measures and driving could not be identified. The findings highlight (a) the potential of cognitive assessments to identify older adults at risk of driving impairment (as part of a larger diagnostic assessment), and (b) the urgent need for prospective longitudinal studies in investigating the impact of age-related changes in cognition on driving performance over time.
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Affiliation(s)
- K B Stefanidis
- MAIC/UniSC Road Safety Research Collaboration, University of the Sunshine Coast, 90 Sippy Downs Dr, Sippy Downs, Queensland 4556, Australia.
| | - T Mieran
- MAIC/UniSC Road Safety Research Collaboration, University of the Sunshine Coast, 90 Sippy Downs Dr, Sippy Downs, Queensland 4556, Australia
| | - C Schiemer
- MAIC/UniSC Road Safety Research Collaboration, University of the Sunshine Coast, 90 Sippy Downs Dr, Sippy Downs, Queensland 4556, Australia
| | - J Freeman
- MAIC/UniSC Road Safety Research Collaboration, University of the Sunshine Coast, 90 Sippy Downs Dr, Sippy Downs, Queensland 4556, Australia
| | - V Truelove
- MAIC/UniSC Road Safety Research Collaboration, University of the Sunshine Coast, 90 Sippy Downs Dr, Sippy Downs, Queensland 4556, Australia
| | - M J Summers
- School of Health & Behavioural Sciences, University of the Sunshine Coast, 90 Sippy Downs Dr, Sippy Downs, Queensland 4556, Australia
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Lyons GCE, Summers MJ, Schultz TJ, Lambell K, Ridley EJ, Fetterplace K, Yandell R, Chapple LS. Protein prescription and delivery practices in critically ill adults: A survey of Australian and New Zealand intensive care dietitians. Aust Crit Care 2021; 35:543-549. [PMID: 34556388 DOI: 10.1016/j.aucc.2021.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Protein provision is thought to be integral to attenuating muscle wasting in critical illness, yet patients receive half of that prescribed. As international guidelines lack definitive evidence to support recommendations, understanding clinicians' views relating to protein practices is of importance. OBJECTIVES The objective of this study was to describe Australia and New Zealand intensive care unit (ICU) dietitians' protein prescription and perceived delivery practices in critically ill adults, including common barriers and associations between ICU clinical experience and protein prescriptions for different clinical conditions. METHODS A 42-item descriptive quantitative survey of Australian and New Zealand intensive care dietitians was disseminated through nutrition and ICU society e-mailing lists. Data were collected on respondent demographics and reported protein practices including questions related to a multitrauma case study. Data were analysed using descriptive and content analysis and reported as n (%). Fisher's exact tests were used to compare experience and protein prescriptions. RESULTS Of the 67 responses received (one excluded due to >50% missing data), more than 80% of respondents stated they would prescribe 1.2-1.5 g protein/kg bodyweight/day for most critically ill patients, most commonly using European Society of Clinical Nutrition and Metabolism (ESPEN) guidelines to support prescriptions (n = 61/66, 92%). Most respondents (n = 49/66, 74%) thought their practice achieved 61-80% of protein prescriptions, with frequently reported barriers including fasting periods (n = 59/66, 89%), avoiding energy overfeeding (n = 50/66, 76%), and gastrointestinal intolerance (n = 47/66, 71%). No associations between years of ICU experience and protein prescriptions for 14 of the 15 predefined clinical conditions were present. CONCLUSIONS Australian and New Zealand ICU dietitians use international guidelines to inform protein prescriptions of 1.2-1.5 g/kg/day for most clinical conditions, and protein prescriptions do not appear to be influenced by years of ICU experience. Key perceived barriers to protein delivery including avoidance of energy overfeeding and gastrointestinal intolerance could be explored to improve protein adequacy.
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Affiliation(s)
- G C E Lyons
- Nutrition and Dietetics, College of Nursing and Health Sciences, Flinders University, Adelaide, South Australia, Australia
| | - M J Summers
- Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia; Intensive Care Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - T J Schultz
- Flinders Health and Medical Research Institute, Flinders University, Adelaide, South Australia, Australia; Adelaide Nursing School, The University of Adelaide, Adelaide, South Australia, Australia
| | - K Lambell
- Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne, Australia; Nutrition Department, Alfred Health, Melbourne, Australia
| | - E J Ridley
- Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne, Australia; Nutrition Department, Alfred Health, Melbourne, Australia
| | - K Fetterplace
- Allied Health Department (Clinical Nutrition), Royal Melbourne Hospital, Melbourne, Australia; The University of Melbourne, Melbourne Medical School, Department of Medicine and Radiology, Royal Melbourne Hospital, Melbourne, Australia
| | - R Yandell
- Department of Clinical Dietetics, Royal Adelaide Hospital, Port Road, Adelaide, South Australia, Australia
| | - L S Chapple
- Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia; Intensive Care Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia.
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Ward DD, Summers MJ, Valenzuela MJ, Srikanth VK, Summers JJ, King AE, Ritchie K, Robinson AL, Vickers JC. Associations of Later-Life Education, the BDNF Val66Met Polymorphism and Cognitive Change in Older Adults. J Prev Alzheimers Dis 2021; 7:37-42. [PMID: 32010924 DOI: 10.14283/jpad.2019.40] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In 358 participants of the Tasmanian Healthy Brain Project, we quantified the cognitive consequences of engaging in varying loads of university-level education in later life, and investigated whether or not BDNF Val66Met affected outcomes. Assessment of neuropsychological, health, and psychosocial function was undertaken at baseline, 12-month, and 24-month follow-up. Education load was positively associated with change in language processing performance, but this effect did not reach statistical significance (P = 0.064). The BDNF Val66Met polymorphism significantly moderated the extent to which education load was associated with improved language processing (P = 0.026), with education load having a significant positive relationship with cognitive change in BDNF Met carriers but not in BDNF Val homozygotes. In older adults who carry BDNF Met, engaging in university-level education improves language processing performance in a load-dependent manner.
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Affiliation(s)
- D D Ward
- David D. Ward, Wicking Dementia Research and Education Centre, Private Bag 143, Hobart, Tasmania 7001, Australia.
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Selvanderan SP, Summers MJ, Plummer MP, Finnis ME, Ali Abdelhamid Y, Anderson MB, Chapman MJ, Rayner CK, Deane AM. Withholding Stress Ulcer Prophylaxis To Mechanically Ventilated Enterally-Fed Critically Ill Patients Appears Safe: A Randomised Double-Blind Placebo Controlled Pilot Study. Intensive Care Med Exp 2015. [PMCID: PMC4797000 DOI: 10.1186/2197-425x-3-s1-a41] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Summers MJ, Selvanderan SP, Plummer MP, Finnis ME, Ali Abdelhamid Y, Anderson MB, Chapman MJ, Rayner CK, Deane AM. COMPARISON OF MACROSCOPIC ABNORMALITIES IN PATIENTS RECEIVING ROUTINE PANTOPRAZOLE WHEN COMPARED TO PLACEBO. Intensive Care Med Exp 2015. [PMCID: PMC4796955 DOI: 10.1186/2197-425x-3-s1-a980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Klekociuk SZ, Summers JJ, Vickers JC, Summers MJ. Reducing false positive diagnoses in mild cognitive impairment: the importance of comprehensive neuropsychological assessment. Eur J Neurol 2014; 21:1330-6, e82-3. [PMID: 24943259 DOI: 10.1111/ene.12488] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/05/2014] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND PURPOSE Longitudinal studies of mild cognitive impairment (MCI) report that a sizeable proportion of MCI cases revert to normal levels of functioning over time. The rate of recovery from MCI indicates that existing MCI diagnostic criteria result in an unacceptably high rate of false positive diagnoses and lack adequate sensitivity and specificity. METHODS The aim of the present study was to identify a set of neuropsychological measures able to differentiate between true positive cases of MCI from those who were unimpaired at 11 months' follow-up. RESULTS A discriminant function analysis identified that a combination of measures of complex sustained attention, semantic memory, working memory, episodic memory and selective attention correctly classified outcome in more than 80% of cases. The rate of false positive diagnoses (5.93%) was considerably lower than is evident in previously published MCI studies. CONCLUSIONS The results of the present study indicate that the rate of false positive MCI diagnoses can be significantly reduced through the use of sensitive and specific neuropsychological measures of memory and non-memory functions.
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Affiliation(s)
- S Z Klekociuk
- School of Medicine, University of Tasmania, Launceston, Tasmania, Australia
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Summers MJ, DI Bartolomeo AE, Zaknic AV, Chapman MJ, Nguyen NQ, Zacharakis B, Rayner CK, Horowitz M, Deane AM. Endogenous amylin and glucagon-like peptide-1 concentrations are not associated with gastric emptying in critical illness. Acta Anaesthesiol Scand 2014; 58:235-42. [PMID: 24410108 DOI: 10.1111/aas.12252] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2013] [Indexed: 02/05/2023]
Abstract
BACKGROUND In health, the hormones amylin and glucagon-like peptide-1 (GLP-1) slow gastric emptying (GE) and modulate glycaemia. The aims of this study were to determine amylin and GLP-1 concentrations in the critically ill and their relationship with GE, glucose absorption and glycaemia. METHODS In fasted critically ill and healthy subjects (n = 26 and 23 respectively), liquid nutrient, containing 100 mg (13) C-sodium octanoate and 3 g 3-O-methlyglucose (3-OMG), was administered via a nasogastric tube. Amylin, GLP-1, glucose and 3-OMG concentrations were measured in blood samples taken during fasting, and 30 min and 60 min after the 'meal'. Breath samples were taken to determine gastric emptying coefficient (GEC). Intolerance to intragastric feeding was defined as a gastric residual volume of ≥ 250 ml and/or vomiting within the 24 h prior to the study. RESULTS Although GE was slower (GEC: critically ill 2.8 ± 0.9 vs. health, 3.4 ± 0.2; P = 0.002), fasting blood glucose was higher (7.0 ± 1.9 vs. 5.7 ± 0.2 mmol/l; P = 0.005) and overall glucose absorption was reduced in critically ill patients (3-OMG: 9.4 ± 8.0 vs. 17.7 ± 4.9 mmol/l.60 min; P < 0.001), there were no differences in fasting or postprandial amylin concentrations. Furthermore, although fasting [1.7 (0.4-7.2) vs. 0.7 (0.3-32.0) pmol/l; P = 0.04] and postprandial [3.0 (0.4-8.5) vs. 0.8 (0.4-34.3) pmol/l; P = 0.02] GLP-1 concentrations were increased in the critically ill and were greater in feed intolerant when compared with those tolerating feed [3.7 (0.4-7.2) vs. 1.2 (0.7-4.6) pmol/l; P = 0.02], there were no relationships between GE and fasting amylin or GLP-1 concentrations. CONCLUSION In the critically ill, fasting GLP-1, but not amylin, concentrations are elevated and associated with feed intolerance. Neither amylin nor GLP-1 appears to substantially influence the rate of GE.
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Affiliation(s)
- M J Summers
- Intensive Care Unit, Level 4, Emergency Services Building, Royal Adelaide Hospital, Adelaide, Australia
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Sim JA, Horowitz M, Summers MJ, Trahair LG, Goud RS, Zaknic AV, Hausken T, Fraser JD, Chapman MJ, Jones KL, Deane AM. Mesenteric blood flow, glucose absorption and blood pressure responses to small intestinal glucose in critically ill patients older than 65 years. Intensive Care Med 2013; 39:258-66. [PMID: 23096428 DOI: 10.1007/s00134-012-2719-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 09/13/2012] [Indexed: 02/07/2023]
Abstract
PURPOSE To compare nutrient-stimulated changes in superior mesenteric artery (SMA) blood flow, glucose absorption and glycaemia in individuals older than 65 years with, and without, critical illness. METHODS Following a 1-h 'observation' period (t (0)-t (60)), 0.9 % saline and glucose (1 kcal/ml) were infused directly into the small intestine at 2 ml/min between t (60)-t (120), and t (120)-t (180), respectively. SMA blood flow was measured using Doppler ultrasonography at t (60) (fasting), t (90) and t (150) and is presented as raw values and nutrient-stimulated increment from baseline (Δ). Glucose absorption was evaluated using serum 3-O-methylglucose (3-OMG) concentrations during, and for 1 h after, the glucose infusion (i.e. t (120)-t (180) and t (120)-t (240)). Mean arterial pressure was recorded between t (60)-t (240). Data are presented as median (25th, 75th percentile). RESULTS Eleven mechanically ventilated critically ill patients [age 75 (69, 79) years] and nine healthy volunteers [70 (68, 77) years] were studied. The magnitude of the nutrient-stimulated increase in SMA flow was markedly less in the critically ill when compared with healthy subjects [Δt (150): patients 115 (-138, 367) versus health 836 (618, 1,054) ml/min; P = 0.001]. In patients, glucose absorption was reduced during, and for 1 h after, the glucose infusion when compared with health [AUC(120-180): 4.571 (2.591, 6.551) versus 11.307 (8.447, 14.167) mmol/l min; P < 0.001 and AUC(120-240): 26.5 (17.7, 35.3) versus 40.6 (31.7, 49.4) mmol/l min; P = 0.031]. A close relationship between the nutrient-stimulated increment in SMA flow and glucose absorption was evident (3-OMG AUC(120-180) and ∆SMA flow at t (150): r (2) = 0.29; P < 0.05). CONCLUSIONS In critically ill patients aged >65 years, stimulation of SMA flow by small intestinal glucose infusion may be attenuated, which could account for the reduction in glucose absorption.
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Affiliation(s)
- Jennifer A Sim
- Discipline of Acute Care Medicine, University of Adelaide, North Terrace, Adelaide, SA, Australia.
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Summers MJ, Summers JJ, White TF, Hannan GJ. The effect of occupational exposure to manganese dust and fume on neuropsychological functioning in Australian smelter workers. J Clin Exp Neuropsychol 2012; 33:692-703. [PMID: 21416424 DOI: 10.1080/13803395.2011.553585] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Chronic low-level occupational exposure to manganese (Mn) is reportedly associated with the development of Parkinsonian-like symptoms. In a study of 143 manganese smelter workers, inhalable Mn exposure was associated with lower performances on the Digit Symbol Coding and Stroop tests; respirable Mn exposure was associated with improved Digit Symbol Coding test performance and reduced performance on the Trail Making (Part A), Matrix Reasoning, and Stroop tests. While these relationships reached statistical significance, the magnitude of these effects was significantly smaller than the standard error of measurement of the neuropsychological tests, indicating that these differences are not of clinical significance.
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Affiliation(s)
- M J Summers
- School of Psychology, University of Tasmania, TAS, Australia.
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Abstract
Activation of memory retrieval after weak learning (WL), during either the short- or intermediate-term stages of memory in day-old chickens, resulted in the strengthening of the memory to levels normally associated with strong learning. Administration of the calcium channel antagonist lanthanum chloride, the glutamate receptor agonist monosodium glutamate, or the N-methyl-D-aspartate glutamatergic receptor antagonist AP5 prevented strengthening of a WL memory by reminder-activated memory retrieval. The results of this study are discussed in light of our recent findings suggesting two phases of memory retrieval in the day-old chick. The results are consistent with the proposition that a memory undergoing the processes of formation may be modified to include information gleaned at the time of memory retrieval and that a second phase of memory retrieval may be responsible for such modification.
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Affiliation(s)
- M J Summers
- Department of Psychology, Monash University, Clayton, Victoria, Australia
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Summers MJ, Crowe SF, Ng KT. Administration of DL-2-amino-5-phosphonovaleric acid (AP5) induces transient inhibition of reminder-activated memory retrieval in day-old chicks. Brain Res Cogn Brain Res 1997; 5:311-21. [PMID: 9197518 DOI: 10.1016/s0926-6410(97)00007-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
DL-2-Amino-5-phosphonovaleric acid (50 microM) administered immediately after a visual reminder presented to day-old chickens between 7.5 min and 24 h following a single trial passive avoidance learning task produced transient losses of memory on retention test, an effect not observed in the absence of a reminder or when the reminder was given 48 h post learning. The duration of the transient deficits decreased with increasing interval between training and the reminder trial. The time of onset of memory loss after the reminder trial appeared to increase with increasing interval between the training and the reminder trials. The results suggest that, for a period of at least up to 24 h after passive avoidance training, retrieval of memory may lead to processes which are sensitive to inhibition by the NMDA receptor antagonist AP5, with the duration of sensitivity post retrieval decreasing as the period of memory consolidation increases. The results extend previously reported findings and suggest the possibility that consolidation of a stable memorial representation of a learning experience may take over several days and may entail the concurrent laying down of a stable retrieval mechanism.
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Affiliation(s)
- M J Summers
- Department of Psychology, Monash University, Clayton, Victoria, Australia
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Summers MJ, Crowe SF, Ng KT. Administration of lanthanum chloride following a reminder induces a transient loss of memory retrieval in day-old chicks. Brain Res Cogn Brain Res 1996; 4:109-19. [PMID: 8883924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Lanthanum chloride (5.0 mM) administered immediately after a visual reminder presented to day-old chickens between 7.5 min and 48 h following a single trial passive avoidance learning task produced an immediate but transient loss of memory on retention test, an effect not observed in the absence of a reminder. The duration of the transient deficit was relatively stable with lanthanum chloride consistently inducing a loss of memory that was evident 5 min after the reminder, with recovery by 10-15 min. The results suggest that, for a period of at least up to 48 h after passive avoidance training, the activation of memory retrieval by a reminder stimulus may lead to processes which are sensitive to inhibition by the calcium channel antagonist lanthanum chloride. These results extend previously reported findings implicating the involvement of glutamate-sensitive channels in a transient memory process that is also activated as a result of a reminder stimulus, but that is no longer present 48 h after training. The glutamate-sensitive mechanism appears to be a secondary mechanism activated following memory retrieval and to be dependent on the level of memory consolidation that the memory for the original experience has undergone. The results presented here suggest that lanthanum chloride, a calcium channel antagonist, inhibits memory retrieval in the day-old chick. This effect implicates calcium channel mediated processes in immediate memory recall. Further, the results suggest the lanthanum inhibits a primary mechanism, that precedes that glutamate-sensitive mechanism identified previously and that both are dependent on the activation of memory retrieval by a reminder.
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Affiliation(s)
- M J Summers
- Department of Psychology, Monash University, Clayton, Vic Australia
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Abstract
Monosodium glutamate (4.0 mM) administered immediately after a visual reminder presented to day-old chickens between 7.5 min and 24 h following a single trial passive avoidance learning task produced transient losses of memory on retention test, an effect not observed in the absence of a reminder or when the reminder was given 48 h post-learning. The duration of the transient deficit decreased with increasing interval between the training and the reminder trial. The time of onset of memory loss after the reminder trial appeared to increase with increasing interval between the training and the reminder trials. The results suggest that, for a period of at least up to 24 h after passive avoidance training, retrieval of memory may lead to processes which are sensitive to inhibition by glutamate, with the duration of sensitivity post-retrieval decreasing as the period of memory consolidation increases. The results extend previously reported findings with rodents and suggest the possibility that consolidation of a stable memorial representation of a learning experience may take place over several days and may entail the concurrent laying down of a stable retrieval mechanism.
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Affiliation(s)
- M J Summers
- School of Psychology, La Trobe University, Victoria, Australia
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Ward A, Summers MJ, Sim E. Purification of recombinant human N-acetyltransferase type 1 (NAT1) expressed in E. coli and characterization of its potential role in folate metabolism. Biochem Pharmacol 1995; 49:1759-67. [PMID: 7598738 DOI: 10.1016/0006-2952(95)00087-g] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Human arylamine N-acetyltransferase type 1 (NAT1) has been cloned from human genomic DNA, into the vector pET(5a) and expressed in Escherichia coli. The recombinant protein has been purified to apparent homogeneity using anion exchange chromatography. The arylamine acceptor specificity, and the effect of potential NAT1 inhibitors has been investigated using purified recombinant protein. The Km of the recombinant NAT1 protein for the substrates para-aminobenzoate (p-aba) and 4-aminosalicylate are 14.3 and 11.8 microM, respectively. Folate and amethopterin were found to be potent competitive inhibitors of p-aba acetylation, with Ki values of 13.3 and 9.5 microM, respectively. The pteroate moiety of folate, in contrast is a poor inhibitor, with 100 microM pteroate inhibiting only 40% of NAT1 activity. A catabolite of folate para-aminobenzoly-L-glutamate has also been shown to be a NAT1 substrate with a Km value of 263 microM.
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Affiliation(s)
- A Ward
- Department of Pharmacology, University of Oxford, U.K
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