146 results on '"MacKenzie AE"'
Search Results
2. The context, measures and outcomes of psychosocial care interventions in long-term health care for older people.
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Mackenzie AE, Lee DTF, and Ross FM
- Abstract
This paper examines the psychosocial dimensions of long-term care with reference to the new International Classification of Functioning, Disability and Handicap (ICIDH 2) and to research conducted in Hong Kong. It also draws on selected international literature about older people. It discusses the different ways in which information can be gained about the personal, social and emotional processes of rehabilitation that influence outcomes and raises methodological questions about the study of interventions. Outcomes that are sensitive to psychosocial interventions and that take account of the elderly person's own perspective are identified as important challenges for nurses and other professionals in the multidisciplinary team, in order to respond to an individualized approach to long-term care. It is concluded that gaining a better understanding of the psychosocial dimensions of long-term care will enhance professional practice and benefit older people and their carers. [ABSTRACT FROM AUTHOR]
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- 2004
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3. Predictors of quality of life following stroke.
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MacKenzie AE and Chang AM
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- 2002
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4. Coping with a child with Down syndrome: the experiences of mothers in Hong Kong.
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Lam L and Mackenzie AE
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Chinese mothers' experiences of parenting a child with Down syndrome were explored through semistructured interviews with 18 key informants selected by purposive sampling. Seven major themes were identified: unexpected birth of an abnormal child, acceptance of the child, special needs of the child, worry about the future, knowledge deficit, effect on the marital relationship, and social restrictions. The types of stressors changed over time according to the child's age, and coping strategies varied accordingly. Strategies frequently used were avoidance, self-reliance, and seeking social support. The particular problems faced by mothers of children with Down syndrome in Hong Kong were discussed in view of the sociocultural background of the region and the highly competitive nature of its society. [ABSTRACT FROM AUTHOR]
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- 2002
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5. Psychosocial consequences of falling: the perspective of older Hong Kong Chinese who had experienced recent falls.
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Kong KS, Lee F, Mackenzie AE, and Lee DTF
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ACCIDENTAL falls ,GERIATRIC psychology ,NURSING ,PSYCHOLOGY - Abstract
AIM OF THE STUDY: The study's aim was to explore the psychosocial consequences of falling with a group of older Chinese who had recently fallen. BACKGROUND: Older people fall more frequently. Thus, the consequences of these falls and their influence on health outcomes need to be determined. One important outcome, namely the psychosocial consequence of falling, has not been extensively studied. As a result, this study explored the psychosocial consequences of falling with a group of older Chinese who had recently experienced a fall. RESEARCH APPROACH: An explorative qualitative approach with semi-structured interviews was used in this study. SAMPLE: Twenty informants, with recent fall experiences either in the community or hospital setting, were interviewed in two elder care wards in an acute care hospital. FINDINGS: Three major categories of psychosocial consequences of falling emerged from the interview data: powerlessness, fear and seeking care. Powerlessness was also exemplified in three subcategories: lack of control, self-comforting and lack of emotion. Informants perceived falls as unpredictable and not preventable, expressing fears that falling could result in dependence on others and becoming a care burden. The interview data also showed that there is a need by older Chinese to seek care and advice from relatives and health care professionals. CONCLUSIONS: Findings from this study have provided insights into the psychosocial consequences of falling for older Chinese. These insights suggest nursing interventions should promote a sense of mastery in prevention of falls, facilitate supportive social interactions with relatives and give empathetic responses to those who have fallen. [ABSTRACT FROM AUTHOR]
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- 2002
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6. A review of older people's experiences with residential care placement.
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Lee DTF, Woo J, and Mackenzie AE
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BACKGROUND: Transition to the care and environment of a residential home has been identified in the literature as the most significant relocation affecting older people. However, little effort has been made systematically to review and synthesize the body of knowledge relating to older people's experiences with such placement. This has led to lack of concerted effort in the development of strategies to help elders adjust to such placement with dignity and success. AIM: This paper presents a critical review of the literature related to older people's experiences with residential care placement, with an attempt to identify how knowledge in this area could be moved forward. CONCLUSIONS: It is concluded that, while understanding of older people's pre and postplacement experiences was abundant, there was a dearth of literature on the actual experiences involved as older people made their day to day adjustment after placement. There is a need for future research to identify the dynamic processes of how older people come to terms with residential living. Future research should also focus on developing an accurate understanding of the adjustment experiences of elders with different ethnic background. [ABSTRACT FROM AUTHOR]
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- 2002
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7. Community care of older Chinese people in Hong Kong: a selective review.
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Lui MHL, Lee DTF, and Mackenzie AE
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- 2000
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8. Needs of families with a relative in a critical care unit in Hong Kong.
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Lee IYM, Chien WT, and Mackenzie AE
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INTENSIVE care units ,NURSES - Abstract
* The aim of this study is to explore family members' perceptions of their immediate needs following admission of a relative to a critical care unit in Hong Kong. * A convenience sample of 30 family members was drawn from those available during the first 96 hours of hospitalization of their relative. * Self-reported questionnaires, consisting of a demographic data sheet, a modified Chinese version of the 45-item Critical Care Family Needs Inventory (CCFNI) and semistructured interviews, are the instruments used to examine family members' perceptions of need importance and to ascertain whether or not these needs are met. * Doctors and nurses are identified as the most suitable people to meet most immediate family needs. * Conclusions are drawn as to the best focus of nursing interventions in order to provide quality care to patients and families. [ABSTRACT FROM AUTHOR]
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- 2000
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9. Chinese elderly patients' perceptions of their rehabilitation needs following a stroke.
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Lui MHL and Mackenzie AE
- Abstract
Stroke is the third leading cause of death and disability among Chinese elderly patients in Hong Kong and yet the rehabilitation needs of these patients are rarely explored. The aim of this study was to identify the rehabilitation needs of Chinese elderly patients following a stroke. The study adopted an ethnographic approach, information being gathered by the researcher through interviews with 15 key informants selected by purposive sampling. The perceptions of patients as to their own needs were sought at three stages of recovery - in the acute and rehabilitation settings and at 1 month following discharge. Ethical approval was gained from the Chinese University Faculty of Medicine ethical committee and access agreed by the hospital authorities. Verbal approval was gained from the patients before each interview, following confirmation of the voluntary nature of participation and assurance of confidentiality and anonymity. The researcher's role was also clearly stated. Analysis of the interview data produced five categories of patient need at the three stages of recovery, namely informational, physical, psychological, social and spiritual. The most frequently stated, but largely unmet, need in all settings was the need for information, particularly information about the reasons for stroke and about the activities that promote recovery. In the acute and rehabilitation settings patients' responses indicated a need to be respected as individuals, to be addressed by name and to be provided with privacy. Although the Barthel Index administered during interviews charted recovery at different rates, nurses did not always make links between the level of functional ability and the help needed with physical tasks. They also failed to recognize the relationship between physical and psychological needs and the equal importance of both in recovery from stroke. As Chinese elderly patients tend to take a passive role in seeking help and information, nurses play a significant role in the identification of individual rehabilitation needs. Implications for nursing practice are discussed. [ABSTRACT FROM AUTHOR]
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- 1999
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10. State self-esteem following stroke.
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Chang AM, Mackenzie AE, Chang, A M, and Mackenzie, A E
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- 1998
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11. Case management: a review of the definitions and practices.
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Lee DTF, Mackenzie AE, Dudley-Brown S, and Chin TM
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HOSPITAL case management services , *COMMUNITY health nursing , *NURSING practice - Abstract
Case management has been suggested as an innovative strategy which facilitates the linking of quality and cost-effective care. However, there is little consensus about what is actually being introduced under the name of case management. It is suggested that this absence of a clear understanding of case management has been an obstacle in moving forward case management practice and research. This paper presents a critical review of the confusion surrounding case management with an attempt to unravel issues relevant to the implementation of case management into community nursing practice in Hong Kong. It is concluded that there is a need for different definitions of case management as a result of the differences in the cultural and health care context in which it is being practised. Also, if case management programmes are to be advanced, there needs to be more co-ordinated effort in researching not only the expected outcomes but also the structures and processess of these programmes so that findings of similar case management programmes can be compared for ways of future improvement. [ABSTRACT FROM AUTHOR]
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- 1998
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12. A review of the historical and social processes contributing to care and caregiving in Chinese families.
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Holroyd EA and Mackenzie AE
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CAREGIVERS , *FAMILIES - Abstract
The purpose of this paper is to review the literature on caring and caregiving in Chinese families in relation to the contribution made by historical and social processes. The beliefs and traditions of care appearing in the professional and popular literature are explored to enable comparison with recent research from Hong Kong, China and the United Kingdom. Caring emerges as profoundly complicated and ambivalent, drawing on notions of morality, obligation, love, kinship and gender responsibility. Furthermore, caring in contemporary Chinese families in Hong Kong appears to have more similarities than differences with western families, possibly due to changing kinship networks. Such conclusions have particular relevance for nursing in the light of recent policy directives in Hong Kong promoting the role of the families in caring for their dependent members based on the assumption that families can and will care. [ABSTRACT FROM AUTHOR]
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- 1995
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13. Evaluating ethnography: considerations for analysis.
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Mackenzie AE
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NURSING practice , *ETHNOLOGY - Abstract
The informed evaluation of ethnographic reports is essential to the practitioner who is working towards research-based practice. It is also part of the process of developing and refining nursing knowledge. While there are features common to the critical examination of all research, an understanding of ethonographic design and, in particular, of issues of validity and reliability, is a prerequisite for evaluation of ethnographic research reports. [ABSTRACT FROM AUTHOR]
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- 1994
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14. Learning from experience in the community: an ethnographic study of district nurse students.
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Mackenzie AE
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NURSING students , *IN-service training of nurses , *TRAINING - Abstract
This study seeks to gain an understanding of the learning experiences of district nurse students in the learning environment of the community, and to examine learning in the practice setting from the perspective of the student. Since the research depends upon the changing and differing interpretations of the individuals involved in the natural setting of the community, an ethnographic approach has been adopted. The experiences of students are monitored throughout the taught practice element of the district nurse course in both inner city and rural/urban locations. Data, collected through interview and observations, are analysed in the context of theory relating to adult learning and learning from experience. Three major categories are identified. Examples from these categories are identified and discussed. The categories are sequential and represent the learning process experienced by the students in the practice setting as they learn to fit into a new environment, test out their own ideas and compare the unreality of college with the reality of practice. Attention is drawn to the difficulties for students of fitting into new settings and trying out change, to the detrimental effect on learning of rigid practice routines and to the powerlessness of community practice teachers to exert a major influence on the learning environment. These issues are discussed in the context of changes in nurse education and evaluation of the community learning environment. [ABSTRACT FROM AUTHOR]
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- 1992
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15. Research in brief. Needs of Chinese families with a relative in a critical care unit.
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Lee IYM, Mackenzie AE, and Chien WT
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- 1999
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16. Research in brief. The psychosocial impact of stroke.
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Chang AM, MacKenzie AE, Yip MP, and Dhillon R
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- 1999
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17. Research in brief. Hospital readmissions among elderly patients in Hong Kong: a preliminary study.
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Lee DTF, MacKenzie AE, Lee IFK, and Chan CWH
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- 1999
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18. Sewer transport conditions and their role in the decay of endogenous SARS-CoV-2 and pepper mild mottle virus from source to collection.
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Mercier É, D'Aoust PM, Eid W, Hegazy N, Kabir P, Wan S, Pisharody L, Renouf E, Stephenson S, Graber TE, MacKenzie AE, and Delatolla R
- Abstract
This study presents a comprehensive analysis of the decay patterns of endogenous SARS-CoV-2 and Pepper mild mottle virus (PMMoV) within wastewaters spiked with stool from infected patients expressing COVID-19 symptoms, and hence explores the decay of endogenous SARS-CoV-2 and PMMoV targets in wastewaters from source to collection of the sample. Stool samples from infected patients were used as endogenous viral material to more accurately mirror real-world decay processes compared to more traditionally used lab-propagated spike-ins. As such, this study includes data on early decay stages of endogenous viral targets in wastewaters that are typically overlooked when performing decay studies on wastewaters harvested from wastewater treatment plants that contain already-degraded endogenous material. The two distinct sewer transport conditions of dynamic suspended sewer transport and bed and near-bed sewer transport were simulated in this study at temperatures of 4 °C, 12 °C and 20 °C to elucidate decay under these two dominant transport conditions within wastewater infrastructure. The dynamic suspended sewer transport was simulated over 35 h, representing typical flow conditions, whereas bed and near-bed transport extended to 60 days to reflect the prolonged settling of solids in sewer systems during reduced flow periods. In dynamic suspended sewer transport, no decay was observed for SARS-CoV-2, PMMoV, or total RNA over the 35-h period, and temperature ranging from 4 °C to 20 °C had no noticeable effect. Conversely, experiments simulating bed and near-bed transport conditions revealed significant decreases in SARS-CoV-2 and total RNA concentrations by day 2, and PMMoV concentrations by day 3. Only PMMoV exhibited a clear trend of increasing decay constant with higher temperatures, suggesting that while temperature influences decay dynamics, its impact may be less significant than previously assumed, particularly for endogenous RNA that is bound to dissolved organic matter in wastewater. First order decay models were inadequate for accurately fitting decay curves of SARS-CoV-2, PMMoV, and total RNA in bed and near-bed transport conditions. F-tests confirmed the superior fit of the two-phase decay model compared to first order decay models across temperatures of 4 °C-20 °C. Finally, and most importantly, total RNA normalization emerged as an appropriate approach for correcting the time decay of SARS-CoV-2 exposed to bed and near-bed transport conditions. These findings highlight the importance of considering decay from the point of entry in the sewers, sewer transport conditions, and normalization strategies when assessing and modelling the impact of viral decay rates in wastewater systems. This study also emphasizes the need for ongoing research into the diverse and multifaceted factors that influence these decay rates, which is crucial for accurate public health monitoring and response strategies., (Copyright © 2024. Published by Elsevier GmbH.)
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- 2024
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19. Corrigendum: Wastewater-based surveillance identifies start to the pediatric respiratory syncytial virus season in two cities in Ontario, Canada.
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Mercier E, Pisharody L, Guy F, Wan S, Hegazy N, D'Aoust PM, Kabir MP, Nguyen TB, Eid W, Harvey B, Rodenburg E, Rutherford C, Mackenzie AE, Willmore J, Hui C, Paes B, Delatolla R, and Thampi N
- Abstract
[This corrects the article DOI: 10.3389/fpubh.2023.1261165.]., Competing Interests: PD'A, EM, and RD hold leadership positions in Advanced Environmental Molecular Analytics Ltd. BP received research funding and/or compensation as advisor/lecturer from AstraZeneca and Sanofi outside the scope of this study. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated., (Copyright © 2024 Mercier, Pisharody, Guy, Wan, Hegazy, D'Aoust, Kabir, Nguyen, Eid, Harvey, Rodenburg, Rutherford, Mackenzie, Willmore, Hui, Paes, Delatolla and Thampi.)
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- 2024
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20. Impact of coagulation on SARS-CoV-2 and PMMoV viral signal in wastewater solids.
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Hegazy N, Tian X, D'Aoust PM, Pisharody L, Towhid ST, Mercier É, Zhang Z, Wan S, Thakali O, Kabir MP, Fang W, Nguyen TB, Ramsay NT, MacKenzie AE, Graber TE, Guilherme S, and Delatolla R
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- Humans, SARS-CoV-2, Sewage, RNA, Viral, Wastewater-Based Epidemiological Monitoring, Wastewater, COVID-19, Ferric Compounds, Tobamovirus
- Abstract
Wastewater surveillance (WWS) of SARS-CoV-2 has become a crucial tool for monitoring COVID-19 cases and outbreaks. Previous studies have indicated that SARS-CoV-2 RNA measurement from testing solid-rich primary sludge yields better sensitivity compared to testing wastewater influent. Furthermore, measurement of pepper mild mottle virus (PMMoV) signal in wastewater allows for precise normalization of SARS-CoV-2 viral signal based on solid content, enhancing disease prevalence tracking. However, despite the widespread adoption of WWS, a knowledge gap remains regarding the impact of ferric sulfate coagulation, commonly used in enhanced primary clarification, the initial stage of wastewater treatment where solids are sedimented and removed, on SARS-CoV-2 and PMMoV quantification in wastewater-based epidemiology. This study examines the effects of ferric sulfate addition, along with the associated pH reduction, on the measurement of SARS-CoV-2 and PMMoV viral measurements in wastewater primary clarified sludge through jar testing. Results show that the addition of Fe
3+ concentrations in the conventional 0 to 60 mg/L range caused no effect on SARS-CoV-2 N1 and N2 gene region measurements in wastewater solids. However, elevated Fe3+ concentrations were shown to be associated with a statistically significant increase in PMMoV viral measurements in wastewater solids, which consequently resulted in the underestimation of PMMoV-normalized SARS-CoV-2 viral signal measurements (N1 and N2 copies/copies of PMMoV). The observed pH reduction from coagulant addition did not contribute to the increased PMMoV measurements, suggesting that this phenomenon arises from the partitioning of PMMoV viral particles into wastewater solids., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)- Published
- 2024
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21. Wastewater-based surveillance identifies start to the pediatric respiratory syncytial virus season in two cities in Ontario, Canada.
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Mercier E, Pisharody L, Guy F, Wan S, Hegazy N, D'Aoust PM, Kabir MP, Nguyen TB, Eid W, Harvey B, Rodenburg E, Rutherford C, Mackenzie AE, Willmore J, Hui C, Paes B, Delatolla R, and Thampi N
- Subjects
- Humans, Child, Palivizumab therapeutic use, Antiviral Agents therapeutic use, Ontario epidemiology, Wastewater-Based Epidemiological Monitoring, Seasons, Cities, Wastewater, Respiratory Syncytial Virus, Human, Respiratory Syncytial Virus Infections epidemiology, Respiratory Syncytial Virus Infections drug therapy
- Abstract
Introduction: Detection of community respiratory syncytial virus (RSV) infections informs the timing of immunoprophylaxis programs and hospital preparedness for surging pediatric volumes. In many jurisdictions, this relies upon RSV clinical test positivity and hospitalization (RSVH) trends, which are lagging indicators. Wastewater-based surveillance (WBS) may be a novel strategy to accurately identify the start of the RSV season and guide immunoprophylaxis administration and hospital preparedness., Methods: We compared citywide wastewater samples and pediatric RSVH in Ottawa and Hamilton between August 1, 2022, and March 5, 2023. 24-h composite wastewater samples were collected daily and 5 days a week at the wastewater treatment facilities in Ottawa and Hamilton, Ontario, Canada, respectively. RSV WBS samples were analyzed in real-time for RSV by RT-qPCR., Results: RSV WBS measurements in both Ottawa and Hamilton showed a lead time of 12 days when comparing the WBS data set to pediatric RSVH data set (Spearman's ρ = 0.90). WBS identify early RSV community transmission and declared the start of the RSV season 36 and 12 days in advance of the provincial RSV season start (October 31) for the city of Ottawa and Hamilton, respectively. The differing RSV start dates in the two cities is likely associated with geographical and regional variation in the incidence of RSV between the cities., Discussion: Quantifying RSV in municipal wastewater forecasted a 12-day lead time of the pediatric RSVH surge and an earlier season start date compared to the provincial start date. These findings suggest an important role for RSV WBS to inform regional health system preparedness, reduce RSV burden, and understand variations in community-related illness as novel RSV vaccines and monoclonal antibodies become available., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Mercier, Pisharody, Guy, Wan, Hegazy, D’Aoust, Kabir, Nguyen, Eid, Harvey, Rodenburg, Rutherford, Mackenzie, Willmore, Hui, Paes, Delatolla and Thampi.)
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- 2023
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22. Rapidly developed, optimized, and applied wastewater surveillance system for real-time monitoring of low-incidence, high-impact MPOX outbreak.
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Wong CH, Zhang Z, Eid W, Plaza-Diaz J, Kabir P, Wan S, Jia JJ, Mercier E, Thakali O, Pisharody L, Hegazy N, Stephenson SE, Fang W, Nguyen TB, Ramsay NT, McKay RM, Corchis-Scott R, MacKenzie AE, Graber TE, D' Aoust PM, and Delatolla R
- Abstract
Recent MPOX viral resurgences have mobilized public health agencies around the world. Recognizing the significant risk of MPOX outbreaks, large-scale human testing, and immunization campaigns have been initiated by local, national, and global public health authorities. Recently, traditional clinical surveillance campaigns for MPOX have been complemented with wastewater surveillance (WWS), building on the effectiveness of existing wastewater programs that were built to monitor SARS-CoV-2 and recently expanded to include influenza and respiratory syncytial virus surveillance in wastewaters. In the present study, we demonstrate and further support the finding that MPOX viral fragments agglomerate in the wastewater solids fraction. Furthermore, this study demonstrates that the current, most commonly used MPOX assays are equally effective at detecting low titers of MPOX viral signal in wastewaters. Finally, MPOX WWS is shown to be more effective at passively tracking outbreaks and/or resurgences of the disease than clinical testing alone in smaller communities with low human clinical case counts of MPOX.
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- 2023
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23. Vorinostat Improves Myotonic Dystrophy Type 1 Splicing Abnormalities in DM1 Muscle Cell Lines and Skeletal Muscle from a DM1 Mouse Model.
- Author
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Neault N, Ravel-Chapuis A, Baird SD, Lunde JA, Poirier M, Staykov E, Plaza-Diaz J, Medina G, Abadía-Molina F, Jasmin BJ, and MacKenzie AE
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- Adult, Animals, Humans, Mice, Alternative Splicing drug effects, Muscle Cells metabolism, Muscle, Skeletal metabolism, RNA, Messenger genetics, Sarcoplasmic Reticulum Calcium-Transporting ATPases metabolism, Trinucleotide Repeat Expansion, Myotonic Dystrophy genetics, RNA Splicing drug effects, Vorinostat metabolism
- Abstract
Myotonic dystrophy type 1 (DM1), the most common form of adult muscular dystrophy, is caused by an abnormal expansion of CTG repeats in the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene. The expanded repeats of the DMPK mRNA form hairpin structures in vitro, which cause misregulation and/or sequestration of proteins including the splicing regulator muscleblind-like 1 (MBNL1). In turn, misregulation and sequestration of such proteins result in the aberrant alternative splicing of diverse mRNAs and underlie, at least in part, DM1 pathogenesis. It has been previously shown that disaggregating RNA foci repletes free MBNL1, rescues DM1 spliceopathy, and alleviates associated symptoms such as myotonia. Using an FDA-approved drug library, we have screened for a reduction of CUG foci in patient muscle cells and identified the HDAC inhibitor, vorinostat, as an inhibitor of foci formation; SERCA1 (sarcoplasmic/endoplasmic reticulum Ca
2+ -ATPase) spliceopathy was also improved by vorinostat treatment. Vorinostat treatment in a mouse model of DM1 (human skeletal actin-long repeat; HSALR ) improved several spliceopathies, reduced muscle central nucleation, and restored chloride channel levels at the sarcolemma. Our in vitro and in vivo evidence showing amelioration of several DM1 disease markers marks vorinostat as a promising novel DM1 therapy.- Published
- 2023
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24. Understanding the dynamic relation between wastewater SARS-CoV-2 signal and clinical metrics throughout the pandemic.
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Hegazy N, Cowan A, D'Aoust PM, Mercier É, Towhid ST, Jia JJ, Wan S, Zhang Z, Kabir MP, Fang W, Graber TE, MacKenzie AE, Guilherme S, and Delatolla R
- Subjects
- Humans, Pandemics, SARS-CoV-2, Wastewater, Wastewater-Based Epidemiological Monitoring, COVID-19 epidemiology, Viral Vaccines
- Abstract
Wastewater surveillance (WWS) of SARS-CoV-2 was proven to be a reliable and complementary tool for population-wide monitoring of COVID-19 disease incidence but was not as rigorously explored as an indicator for disease burden throughout the pandemic. Prior to global mass immunization campaigns and during the spread of the wildtype COVID-19 and the Alpha variant of concern (VOC), viral measurement of SARS-CoV-2 in wastewater was a leading indicator for both COVID-19 incidence and disease burden in communities. As the two-dose vaccination rates escalated during the spread of the Delta VOC in Jul. 2021 through Dec. 2021, relations weakened between wastewater signal and community COVID-19 disease incidence and maintained a strong relationship with clinical metrics indicative of disease burden (new hospital admissions, ICU admissions, and deaths). Further, with the onset of the vaccine-resistant Omicron BA.1 VOC in Dec. 2021 through Mar. 2022, wastewater again became a strong indicator of both disease incidence and burden during a period of limited natural immunization (no recent infection), vaccine escape, and waned vaccine effectiveness. Lastly, with the populations regaining enhanced natural and vaccination immunization shortly prior to the onset of the Omicron BA.2 VOC in mid-Mar 2022, wastewater is shown to be a strong indicator for both disease incidence and burden. Hospitalization-to-wastewater ratio is further shown to be a good indicator of VOC virulence when widespread clinical testing is limited. In the future, WWS is expected to show moderate indication of incidence and strong indication of disease burden in the community during future potential seasonal vaccination campaigns., Competing Interests: Declaration of competing interest The authors declare that no competing financial interests or personal relationships influenced the work reported in this manuscript., (Copyright © 2022. Published by Elsevier B.V.)
- Published
- 2022
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25. Wastewater to clinical case (WC) ratio of COVID-19 identifies insufficient clinical testing, onset of new variants of concern and population immunity in urban communities.
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D'Aoust PM, Tian X, Towhid ST, Xiao A, Mercier E, Hegazy N, Jia JJ, Wan S, Kabir MP, Fang W, Fuzzen M, Hasing M, Yang MI, Sun J, Plaza-Diaz J, Zhang Z, Cowan A, Eid W, Stephenson S, Servos MR, Wade MJ, MacKenzie AE, Peng H, Edwards EA, Pang XL, Alm EJ, Graber TE, and Delatolla R
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- Humans, SARS-CoV-2, Pandemics, Wastewater, Wastewater-Based Epidemiological Monitoring, COVID-19 epidemiology
- Abstract
Clinical testing has been the cornerstone of public health monitoring and infection control efforts in communities throughout the COVID-19 pandemic. With the anticipated reduction of clinical testing as the disease moves into an endemic state, SARS-CoV-2 wastewater surveillance (WWS) will have greater value as an important diagnostic tool. An in-depth analysis and understanding of the metrics derived from WWS is required to interpret and utilize WWS-acquired data effectively (McClary-Gutierrez et al., 2021; O'Keeffe, 2021). In this study, the SARS-CoV-2 wastewater signal to clinical cases (WC) ratio was investigated across seven cities in Canada over periods ranging from 8 to 21 months. This work demonstrates that significant increases in the WC ratio occurred when clinical testing eligibility was modified to appointment-only testing, identifying a period of insufficient clinical testing (resulting in a reduction to testing access and a reduction in the number of daily tests) in these communities, despite increases in the wastewater signal. Furthermore, the WC ratio decreased significantly in 6 of the 7 studied locations, serving as a potential signal of the emergence of the Alpha variant of concern (VOC) in a relatively non-immunized community (40-60 % allelic proportion), while a more muted decrease in the WC ratio signaled the emergence of the Delta VOC in a relatively well-immunized community (40-60 % allelic proportion). Finally, a significant decrease in the WC ratio signaled the emergence of the Omicron VOC, likely because of the variant's greater effectiveness at evading immunity, leading to a significant number of new reported clinical cases, even when community immunity was high. The WC ratio, used as an additional monitoring metric, could complement clinical case counts and wastewater signals as individual metrics in its potential ability to identify important epidemiological occurrences, adding value to WWS as a diagnostic technology during the COVID-19 pandemic and likely for future pandemics., Competing Interests: Declaration of competing interest The authors declare that no known competing financial interests or personal relationships influenced the work reported in this manuscript., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2022
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26. Physical Activity, Gut Microbiota, and Genetic Background for Children and Adolescents with Autism Spectrum Disorder.
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Plaza-Diaz J, Radar AM, Baig AT, Leyba MF, Costabel MM, Zavala-Crichton JP, Sanchez-Martinez J, MacKenzie AE, and Solis-Urra P
- Abstract
It is estimated that one in 100 children worldwide has been diagnosed with autism spectrum disorder (ASD). Children with ASD frequently suffer from gut dysbiosis and gastrointestinal issues, findings which possibly play a role in the pathogenesis and/or severity of their condition. Physical activity may have a positive effect on the composition of the intestinal microbiota of healthy adults. However, the effect of exercise both on the gastrointestinal problems and intestinal microbiota (and thus possibly on ASD) itself in affected children is unknown. In terms of understanding the physiopathology and manifestations of ASD, analysis of the gut-brain axis holds some promise. Here, we discuss the physiopathology of ASD in terms of genetics and microbiota composition, and how physical activity may be a promising non-pharmaceutical approach to improve ASD-related symptoms.
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- 2022
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27. Municipal and neighbourhood level wastewater surveillance and subtyping of an influenza virus outbreak.
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Mercier E, D'Aoust PM, Thakali O, Hegazy N, Jia JJ, Zhang Z, Eid W, Plaza-Diaz J, Kabir MP, Fang W, Cowan A, Stephenson SE, Pisharody L, MacKenzie AE, Graber TE, Wan S, and Delatolla R
- Subjects
- Disease Outbreaks, Humans, Pandemics, Sewage, Wastewater, Wastewater-Based Epidemiological Monitoring, COVID-19, Influenza A Virus, H1N1 Subtype, Influenza, Human epidemiology
- Abstract
Recurrent influenza epidemics and pandemic potential are significant risks to global health. Public health authorities use clinical surveillance to locate and monitor influenza and influenza-like cases and outbreaks to mitigate hospitalizations and deaths. Currently, global integration of clinical surveillance is the only reliable method for reporting influenza types and subtypes to warn of emergent pandemic strains. The utility of wastewater surveillance (WWS) during the COVID-19 pandemic as a less resource intensive replacement or complement for clinical surveillance has been predicated on analyzing viral fragments in wastewater. We show here that influenza virus targets are stable in wastewater and partitions favorably to the solids fraction. By quantifying, typing, and subtyping the virus in municipal wastewater and primary sludge during a community outbreak, we forecasted a citywide flu outbreak with a 17-day lead time and provided population-level viral subtyping in near real-time to show the feasibility of influenza virus WWS at the municipal and neighbourhood levels in near real time using minimal resources and infrastructure., (© 2022. The Author(s).)
- Published
- 2022
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28. Timing of therapy and neurodevelopmental outcomes in 18 families with pyridoxine-dependent epilepsy.
- Author
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Tseng LA, Abdenur JE, Andrews A, Aziz VG, Bok LA, Boyer M, Buhas D, Hartmann H, Footitt EJ, Grønborg S, Janssen MCH, Longo N, Lunsing RJ, MacKenzie AE, Wijburg FA, Gospe SM Jr, Coughlin CR 2nd, and van Karnebeek CDM
- Subjects
- Activities of Daily Living, Cohort Studies, Epilepsy, Humans, Retrospective Studies, Lysine, Pyridoxine therapeutic use
- Abstract
Background: Seventy-five percent of patients with pyridoxine-dependent epilepsy due to α-aminoadipic semialdehyde dehydrogenase deficiency (PDE-ALDH7A1) suffer intellectual developmental disability despite pyridoxine treatment. Adjunct lysine reduction therapies (LRT), aimed at lowering putative neurotoxic metabolites, are associated with improved cognitive outcomes. However, possibly due to timing of treatment, not all patients have normal intellectual function., Methods: This retrospective, multi-center cohort study evaluated the effect of timing of pyridoxine monotherapy and pyridoxine with adjunct LRT on neurodevelopmental outcome. Patients with confirmed PDE-ALDH7A1 with at least one sibling with PDE-ALDH7A1 and a difference in age at treatment initiation were eligible and identified via the international PDE registry, resulting in thirty-seven patients of 18 families. Treatment regimen was pyridoxine monotherapy in ten families and pyridoxine with adjunct LRT in the other eight. Primary endpoints were standardized and clinically assessed neurodevelopmental outcomes. Clinical neurodevelopmental status was subjectively assessed over seven domains: overall neurodevelopment, speech/language, cognition, fine and gross motor skills, activities of daily living and behavioral/psychiatric abnormalities., Results: The majority of early treated siblings on pyridoxine monotherapy performed better than their late treated siblings on the clinically assessed domain of fine motor skills. For siblings on pyridoxine and adjunct LRT, the majority of early treated siblings performed better on clinically assessed overall neurodevelopment, cognition, and behavior/psychiatry. Fourteen percent of the total cohort was assessed as normal on all domains., Conclusion: Early treatment with pyridoxine and adjunct LRT may be beneficial for neurodevelopmental outcome. When evaluating a more extensive neurodevelopmental assessment, the actual impairment rate may be higher than the 75% reported in literature., Take- Home Message: Early initiation of lysine reduction therapies adjunct to pyridoxine treatment in patients with PDE-ALDH7A1 may result in an improved neurodevelopmental outcome., Competing Interests: Declaration of Competing Interest The authors report no competing interests., (Copyright © 2022. Published by Elsevier Inc.)
- Published
- 2022
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29. Quantitation of phosphatidylethanols in dried blood spots to determine rates of prenatal alcohol exposure in Ontario.
- Author
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DiBattista A, Ogrel S, MacKenzie AE, and Chakraborty P
- Subjects
- Biomarkers blood, Dried Blood Spot Testing statistics & numerical data, Female, Humans, Infant, Newborn, Male, Neonatal Screening methods, Ontario epidemiology, Pregnancy, Prenatal Exposure Delayed Effects blood, Prevalence, Retrospective Studies, Tandem Mass Spectrometry, Glycerophospholipids blood, Prenatal Exposure Delayed Effects epidemiology
- Abstract
Background: Estimating rates of prenatal alcohol exposure (PAE) in a population is necessary to ensure that proper medical and social supports and interventions are in place. This study sought to estimate PAE in Ontario, Canada by quantifying phosphatidylethanol (PEth) homologues in over 2000 residual neonatal dried blood spots (DBS)., Methods: A random selection of 2011 residual DBS collected over a 1-week time period were anonymized and extracted. A targeted liquid chromatography-mass spectrometry method was used to quantify 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanol (PEth (16:0/18:1) or POPEth), the clinically accepted biomarker, and six additional PEth homologues. A POPEth level above the United States Drug Testing Laboratories (USDTL) cutoff up to 4 weeks predelivery was indicative of PAE. All PEth homologues were correlated to one another and logistic regression was used to determine the association between PAE status and infant characteristics., Results: The estimated rate of PAE in Ontario, up to the last 4 weeks of gestation, was 15.5% (POPEth >28.5 nM). Most PEth homologues were moderately to strongly correlated to one another. A low birth weight and preterm birth were both associated with PAE, while being small for gestational age had lower odds of PAE., Conclusions: The results of this study suggest that PAE may be more prevalent in Ontario than previous estimates by self-report or meconium testing. These findings support the need to consider the effectiveness of current interventions and the design of new interventions to address this significant public health issue., (© 2022 by the Research Society on Alcoholism.)
- Published
- 2022
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30. COVID-19 wastewater surveillance in rural communities: Comparison of lagoon and pumping station samples.
- Author
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D'Aoust PM, Towhid ST, Mercier É, Hegazy N, Tian X, Bhatnagar K, Zhang Z, Naughton CC, MacKenzie AE, Graber TE, and Delatolla R
- Subjects
- Humans, RNA, Viral, Rural Population, SARS-CoV-2, Wastewater, Wastewater-Based Epidemiological Monitoring, COVID-19
- Abstract
Wastewater-based epidemiology/wastewater surveillance has been a topic of significant interest over the last year due to its application in SARS-CoV-2 surveillance to track prevalence of COVID-19 in communities. Although SARS-CoV-2 surveillance has been applied in more than 50 countries to date, the application of this surveillance has been largely focused on relatively affluent urban and peri-urban communities. As such, there is a knowledge gap regarding the implementation of reliable wastewater surveillance in small and rural communities for the purpose of tracking rates of incidence of COVID-19 and other pathogens or biomarkers. This study examines the relationships existing between SARS-CoV-2 viral signal from wastewater samples harvested from an upstream pumping station and from an access port at a downstream wastewater treatment lagoon with the community's COVID-19 rate of incidence (measured as percent test positivity) in a small, rural community in Canada. Real-time quantitative polymerase chain reaction (RT-qPCR) targeting the N1 and N2 genes of SARS-CoV-2 demonstrate that all 24-h composite samples harvested from the pumping station over a period of 5.5 weeks had strong viral signal, while all samples 24-h composite samples harvested from the lagoon over the same period were below the limit of quantification. RNA concentrations and integrity of samples harvested from the lagoon were both lower and more variable than from samples from the upstream pumping station collected on the same date, indicating a higher overall stability of SARS-CoV-2 RNA upstream of the lagoon. Additionally, measurements of PMMoV signal in wastewater allowed normalizing SARS-CoV-2 viral signal for fecal matter content, permitting the detection of actual changes in community prevalence with a high level of granularity. As a result, in sewered small and rural communities or low-income regions operating wastewater lagoons, samples for wastewater surveillance should be harvested from pumping stations or the sewershed as opposed to lagoons., Competing Interests: Declaration of competing interest The authors declare that no known competing financial interests or personal relationships could appear to influence the work reported in this manuscript., (Copyright © 2021 Elsevier B.V. All rights reserved.)
- Published
- 2021
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31. G Protein-Coupled Receptor GPR35 Suppresses Lipid Accumulation in Hepatocytes.
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Lin LC, Quon T, Engberg S, Mackenzie AE, Tobin AB, and Milligan G
- Abstract
Although prevalent, nonalcoholic fatty liver disease is not currently treated effectively with medicines. Initially, using wild-type and genome-edited clones of the human hepatocyte cell line HepG2, we show that activation of the orphan G protein-coupled receptor GPR35 is both able and sufficient to block liver X-receptor-mediated lipid accumulation. Studies on hepatocytes isolated from both wild-type and GPR35 knock-out mice were consistent with a similar effect of GPR35 agonists in these cells, but because of marked differences in the pharmacology of GPR35 agonists and antagonists at the mouse and human orthologues, as well as elevated basal lipid levels in hepatocytes from the GPR35 knock-out mice, no definitive conclusion could be reached. To overcome this, we generated and characterized a transgenic knock-in mouse line in which the corresponding human GPR35 splice variant replaced the mouse orthologue. In hepatocytes from these humanized GPR35 mice, activation of this receptor was shown conclusively to prevent, and also reverse, lipid accumulation induced by liver X-receptor stimulation. These studies highlight the potential to target GPR35 in the context of fatty liver diseases., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)
- Published
- 2021
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32. Anatomy and White Matter Connections of the Superior Parietal Lobule.
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Lin YH, Dadario NB, Hormovas J, Young IM, Briggs RG, MacKenzie AE, Palejwala AH, Fonseka RD, Kim SJ, Tanglay O, Fletcher LR, Abraham CJ, Conner AK, O'Donoghue DL, and Sughrue ME
- Subjects
- Adult, Humans, Nerve Net, Neural Pathways diagnostic imaging, Parietal Lobe diagnostic imaging, Connectome, White Matter diagnostic imaging
- Abstract
Background: The superior parietal lobule (SPL) is involved in somatosensory and visuospatial integration with additional roles in attention, written language, and working memory. A detailed understanding of the exact location and nature of associated white matter tracts could improve surgical decisions and subsequent postoperative morbidity related to surgery in and around this gyrus., Objective: To characterize the fiber tracts of the SPL based on relationships to other well-known neuroanatomic structures through diffusion spectrum imaging (DSI)-based fiber tracking validated by gross anatomical dissection as ground truth., Methods: Neuroimaging data of 10 healthy, adult control subjects was obtained from a publicly accessible database published in Human Connectome Project for subsequent tractographic analyses. White matter tracts were mapped between both cerebral hemispheres, and a lateralization index was calculated based on resultant tract volumes. Post-mortem dissections of 10 cadavers identified the location of major tracts and validated our tractography results based on qualitative visual agreement., Results: We identified 9 major connections of the SPL: U-fiber, superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, middle longitudinal fasciculus, extreme capsule, vertical occipital fasciculus, cingulum, and corpus callosum. There was no significant fiber lateralization detected., Conclusion: The SPL is an important region implicated in a variety of tasks involving visuomotor and visuospatial integration. Improved understanding of the fiber bundle anatomy elucidated in this study can provide invaluable information for surgical treatment decisions related to this region., (© Congress of Neurological Surgeons 2021.)
- Published
- 2021
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33. Catching a resurgence: Increase in SARS-CoV-2 viral RNA identified in wastewater 48 h before COVID-19 clinical tests and 96 h before hospitalizations.
- Author
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D'Aoust PM, Graber TE, Mercier E, Montpetit D, Alexandrov I, Neault N, Baig AT, Mayne J, Zhang X, Alain T, Servos MR, Srikanthan N, MacKenzie M, Figeys D, Manuel D, Jüni P, MacKenzie AE, and Delatolla R
- Subjects
- Cities, Hospitalization, Humans, RNA, Viral, Retrospective Studies, SARS-CoV-2, Wastewater, COVID-19
- Abstract
Curtailing the Spring 2020 COVID-19 surge required sweeping and stringent interventions by governments across the world. Wastewater-based COVID-19 epidemiology programs have been initiated in many countries to provide public health agencies with a complementary disease tracking metric and non-discriminating surveillance tool. However, their efficacy in prospectively capturing resurgences following a period of low prevalence is unclear. In this study, the SARS-CoV-2 viral signal was measured in primary clarified sludge harvested every two days at the City of Ottawa's water resource recovery facility during the summer of 2020, when clinical testing recorded daily percent positivity below 1%. In late July, increases of >400% in normalized SARS-CoV-2 RNA signal in wastewater were identified 48 h prior to reported >300% increases in positive cases that were retrospectively attributed to community-acquired infections. During this resurgence period, SARS-CoV-2 RNA signal in wastewater preceded the reported >160% increase in community hospitalizations by approximately 96 h. This study supports wastewater-based COVID-19 surveillance of populations in augmenting the efficacy of diagnostic testing, which can suffer from sampling biases or timely reporting as in the case of hospitalization census., Competing Interests: Declaration of competing interest The authors declare that no known competing financial interests or personal relationships could appear to influence the work reported in this manuscript., (Copyright © 2021 Elsevier B.V. All rights reserved.)
- Published
- 2021
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34. G-protein coupled receptor 35 (GPR35) regulates the colonic epithelial cell response to enterotoxigenic Bacteroides fragilis.
- Author
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Boleij A, Fathi P, Dalton W, Park B, Wu X, Huso D, Allen J, Besharati S, Anders RA, Housseau F, Mackenzie AE, Jenkins L, Milligan G, Wu S, and Sears CL
- Subjects
- Animals, Bacteroides fragilis genetics, Bacteroides fragilis metabolism, Colitis etiology, Colitis metabolism, Colon drug effects, Colon metabolism, Colon microbiology, Epithelial Cells drug effects, Epithelial Cells metabolism, Epithelial Cells microbiology, Gastrointestinal Tract drug effects, Gastrointestinal Tract metabolism, Gastrointestinal Tract microbiology, Mice, Mice, Inbred C57BL, Bacterial Toxins administration & dosage, Bacteroides fragilis pathogenicity, Colitis pathology, Colon pathology, Epithelial Cells pathology, Gastrointestinal Tract pathology, Metalloendopeptidases administration & dosage, Receptors, G-Protein-Coupled physiology
- Abstract
G protein-coupled receptor (GPR)35 is highly expressed in the gastro-intestinal tract, predominantly in colon epithelial cells (CEC), and has been associated with inflammatory bowel diseases (IBD), suggesting a role in gastrointestinal inflammation. The enterotoxigenic Bacteroides fragilis (ETBF) toxin (BFT) is an important virulence factor causing gut inflammation in humans and animal models. We identified that BFT signals through GPR35. Blocking GPR35 function in CECs using the GPR35 antagonist ML145, in conjunction with shRNA knock-down and CRISPRcas-mediated knock-out, resulted in reduced CEC-response to BFT as measured by E-cadherin cleavage, beta-arrestin recruitment and IL-8 secretion. Importantly, GPR35 is required for the rapid onset of ETBF-induced colitis in mouse models. GPR35-deficient mice showed reduced death and disease severity compared to wild-type C57Bl6 mice. Our data support a role for GPR35 in the CEC and mucosal response to BFT and underscore the importance of this molecule for sensing ETBF in the colon.
- Published
- 2021
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35. Anatomy and White Matter Connections of the Parahippocampal Gyrus.
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Lin YH, Dhanaraj V, Mackenzie AE, Young IM, Tanglay O, Briggs RG, Chakraborty AR, Hormovas J, Fonseka RD, Kim SJ, Yeung JT, Teo C, and Sughrue ME
- Subjects
- Adult, Connectome methods, Diffusion Tensor Imaging methods, Female, Humans, Male, Middle Aged, Nerve Net anatomy & histology, Nerve Net diagnostic imaging, Parahippocampal Gyrus anatomy & histology, Parahippocampal Gyrus diagnostic imaging, White Matter anatomy & histology, White Matter diagnostic imaging
- Abstract
Background: The parahippocampal gyrus is understood to have a role in high cognitive functions including memory encoding and retrieval and visuospatial processing. A detailed understanding of the exact location and nature of associated white tracts could significantly improve postoperative morbidity related to declining capacity. Through diffusion tensor imaging-based fiber tracking validated by gross anatomic dissection as ground truth, we have characterized these connections based on relationships to other well-known structures., Methods: Diffusion imaging from the Human Connectome Project for 10 healthy adult controls was used for tractography analysis. We evaluated the parahippocampal gyrus as a whole based on connectivity with other regions. All parahippocampal gyrus tracts were mapped in both hemispheres, and a lateralization index was calculated with resultant tract volumes., Results: We identified 2 connections of the parahippocampal gyrus: inferior longitudinal fasciculus and cingulum. Lateralization of the cingulum was detected (P < 0.05)., Conclusions: The parahippocampal gyrus is an important center for memory processing. Subtle differences in executive functioning following surgery for limbic tumors may be better understood in the context of the fiber-bundle anatomy highlighted by this study., (Copyright © 2021 Elsevier Inc. All rights reserved.)
- Published
- 2021
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36. Quantitative analysis of SARS-CoV-2 RNA from wastewater solids in communities with low COVID-19 incidence and prevalence.
- Author
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D'Aoust PM, Mercier E, Montpetit D, Jia JJ, Alexandrov I, Neault N, Baig AT, Mayne J, Zhang X, Alain T, Langlois MA, Servos MR, MacKenzie M, Figeys D, MacKenzie AE, Graber TE, and Delatolla R
- Subjects
- Humans, Incidence, Pandemics, Prevalence, RNA, Ribosomal, 16S, Residence Characteristics, SARS-CoV-2, Wastewater, Betacoronavirus, COVID-19, Coronavirus Infections epidemiology, Pneumonia, Viral epidemiology
- Abstract
In the absence of an effective vaccine to prevent COVID-19 it is important to be able to track community infections to inform public health interventions aimed at reducing the spread and therefore reduce pressures on health-care, improve health outcomes and reduce economic uncertainty. Wastewater surveillance has rapidly emerged as a potential tool to effectively monitor community infections through measuring trends of RNA signal in wastewater systems. In this study SARS-CoV-2 viral RNA N1 and N2 gene regions are quantified in solids collected from influent post grit solids (PGS) and primary clarified sludge (PCS) in two water resource recovery facilities (WRRF) serving Canada's national capital region, i.e., the City of Ottawa, ON (pop. ≈ 1.1M) and the City of Gatineau, QC (pop. ≈ 280K). PCS samples show signal inhibition using RT-ddPCR compared to RT-qPCR, with PGS samples showing similar quantifiable concentrations of RNA using both assays. RT-qPCR shows higher frequency of detection of N1 and N2 gene regions in PCS (92.7, 90.6%, n = 6) as compared to PGS samples (79.2, 82.3%, n = 5). Sampling of PCS may therefore be an effective approach for SARS-CoV-2 viral quantification, especially during periods of declining and low COVID-19 incidence in the community. The pepper mild mottle virus (PMMoV) is determined to have a less variable RNA signal in PCS over a three month period for two WRRFs, regardless of environmental conditions, compared to Bacteroides 16S rRNA or human 18S rRNA, making PMMoV a potentially useful biomarker for normalization of SARS-CoV-2 signal. PMMoV-normalized PCS RNA signal from WRRFs of two cities correlated with the regional public health epidemiological metrics, identifying PCS normalized to a fecal indicator (PMMoV) as a potentially effective tool for monitoring trends during decreasing and low-incidence of infection of SARS-Cov-2 in communities., Competing Interests: Declaration of Competing Interest The authors declare that no known competing financial interests or personal relationships could appear to influence the work reported in this manuscript., (Copyright © 2020. Published by Elsevier Ltd.)
- Published
- 2021
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37. Author Correction: Combinatorial expression of GPCR isoforms affects signalling and drug responses.
- Author
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Marti-Solano M, Crilly SE, Malinverni D, Munk C, Harris M, Pearce A, Quon T, Mackenzie AE, Wang X, Peng J, Tobin AB, Ladds G, Milligan G, Gloriam DE, Puthenveedu MA, and Babu MM
- Published
- 2020
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38. Combinatorial expression of GPCR isoforms affects signalling and drug responses.
- Author
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Marti-Solano M, Crilly SE, Malinverni D, Munk C, Harris M, Pearce A, Quon T, Mackenzie AE, Wang X, Peng J, Tobin AB, Ladds G, Milligan G, Gloriam DE, Puthenveedu MA, and Babu MM
- Subjects
- Databases, Factual, Gene Expression Profiling, HEK293 Cells, Humans, Molecular Targeted Therapy, Organ Specificity drug effects, Protein Isoforms genetics, Proteomics, Receptors, G-Protein-Coupled antagonists & inhibitors, Receptors, G-Protein-Coupled genetics, Signal Transduction genetics, Single-Cell Analysis, Protein Isoforms chemistry, Protein Isoforms metabolism, Receptors, G-Protein-Coupled chemistry, Receptors, G-Protein-Coupled metabolism, Signal Transduction drug effects, Transcriptome
- Abstract
G-protein-coupled receptors (GPCRs) are membrane proteins that modulate physiology across human tissues in response to extracellular signals. GPCR-mediated signalling can differ because of changes in the sequence
1,2 or expression3 of the receptors, leading to signalling bias when comparing diverse physiological systems4 . An underexplored source of such bias is the generation of functionally diverse GPCR isoforms with different patterns of expression across different tissues. Here we integrate data from human tissue-level transcriptomes, GPCR sequences and structures, proteomics, single-cell transcriptomics, population-wide genetic association studies and pharmacological experiments. We show how a single GPCR gene can diversify into several isoforms with distinct signalling properties, and how unique isoform combinations expressed in different tissues can generate distinct signalling states. Depending on their structural changes and expression patterns, some of the detected isoforms may influence cellular responses to drugs and represent new targets for developing drugs with improved tissue selectivity. Our findings highlight the need to move from a canonical to a context-specific view of GPCR signalling that considers how combinatorial expression of isoforms in a particular cell type, tissue or organism collectively influences receptor signalling and drug responses.- Published
- 2020
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39. Electrophysiological Alterations of Pyramidal Cells and Interneurons of the CA1 Region of the Hippocampus in a Novel Mouse Model of Dravet Syndrome.
- Author
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Dyment DA, Schock SC, Deloughery K, Tran MH, Ure K, Nutter LMJ, Creighton A, Yuan J, Banderali U, Comas T, Baumann E, Jezierski A, Boycott KM, Mackenzie AE, and Martina M
- Subjects
- Animals, CA1 Region, Hippocampal metabolism, Electrophysiology, Epilepsies, Myoclonic genetics, Epilepsies, Myoclonic metabolism, Female, Fibroblasts metabolism, Humans, Induced Pluripotent Stem Cells metabolism, Interneurons metabolism, Male, Membrane Potentials, Mice, Mice, Inbred C57BL, Mutation, NAV1.1 Voltage-Gated Sodium Channel genetics, NAV1.1 Voltage-Gated Sodium Channel metabolism, Pyramidal Cells metabolism, CA1 Region, Hippocampal pathology, Disease Models, Animal, Epilepsies, Myoclonic pathology, Fibroblasts pathology, Induced Pluripotent Stem Cells pathology, Interneurons pathology, Pyramidal Cells pathology
- Abstract
Dravet syndrome is a developmental epileptic encephalopathy caused by pathogenic variation in SCN1A To characterize the pathogenic substitution (p.H939R) of a local individual with Dravet syndrome, fibroblast cells from the individual were reprogrammed to pluripotent stem cells and differentiated into neurons. Sodium currents of these neurons were compared with healthy control induced neurons. A novel Scn1a
H939R/+ mouse model was generated with the p.H939R substitution. Immunohistochemistry and electrophysiological experiments were performed on hippocampal slices of Scn1aH939R/+ mice. We found that the sodium currents recorded in the proband-induced neurons were significantly smaller and slower compared to wild type (WT). The resting membrane potential and spike amplitude were significantly depolarized in the proband-induced neurons. Similar differences in resting membrane potential and spike amplitude were observed in the interneurons of the hippocampus of Scn1aH939R/+ mice. The Scn1aH939R/+ mice showed the characteristic features of a Dravet-like phenotype: increased mortality and both spontaneous and heat-induced seizures. Immunohistochemistry showed a reduction in amount of parvalbumin and vesicular acetylcholine transporter in the hippocampus of Scn1aH939R/+ compared to WT mice. Overall, these results underline hyper-excitability of the hippocampal CA1 circuit of this novel mouse model of Dravet syndrome which, under certain conditions, such as temperature, can trigger seizure activity. This hyper-excitability is due to the altered electrophysiological properties of pyramidal neurons and interneurons which are caused by the dysfunction of the sodium channel bearing the p.H939R substitution. This novel Dravet syndrome model also highlights the reduction in acetylcholine and the contribution of pyramidal cells, in addition to interneurons, to network hyper-excitability., (Copyright © 2020 by the Genetics Society of America.)- Published
- 2020
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40. Receptor selectivity between the G proteins Gα 12 and Gα 13 is defined by a single leucine-to-isoleucine variation.
- Author
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Mackenzie AE, Quon T, Lin LC, Hauser AS, Jenkins L, Inoue A, Tobin AB, Gloriam DE, Hudson BD, and Milligan G
- Subjects
- Cell Line, Computational Biology, GTP-Binding Protein alpha Subunits, G12-G13 chemistry, GTP-Binding Protein alpha Subunits, G12-G13 genetics, GTP-Binding Protein alpha Subunits, Gq-G11 chemistry, GTP-Binding Protein alpha Subunits, Gq-G11 genetics, GTP-Binding Protein alpha Subunits, Gq-G11 metabolism, Humans, Isoleucine genetics, Kinetics, Leucine genetics, Luminescent Measurements, Protein Binding, Receptors, G-Protein-Coupled chemistry, Receptors, G-Protein-Coupled genetics, Receptors, G-Protein-Coupled metabolism, Transforming Growth Factor alpha chemistry, Transforming Growth Factor alpha genetics, Transforming Growth Factor alpha metabolism, beta-Arrestins chemistry, beta-Arrestins genetics, beta-Arrestins metabolism, GTP-Binding Protein alpha Subunits, G12-G13 metabolism, Isoleucine chemistry, Leucine chemistry
- Abstract
Despite recent advances in structural definition of GPCR-G protein complexes, the basis of receptor selectivity between G proteins remains unclear. The Gα
12 and Gα13 subtypes together form the least studied group of heterotrimeric G proteins. G protein-coupled receptor 35 (GPR35) has been suggested to couple efficiently to Gα13 but weakly to Gα12 . Using combinations of cells genome-edited to not express G proteins and bioluminescence resonance energy transfer-based sensors, we confirmed marked selectivity of GPR35 for Gα13 . Incorporating Gα12 /Gα13 chimeras and individual residue swap mutations into these sensors defined that selectivity between Gα13 and Gα12 was imbued largely by a single leucine-to-isoleucine variation at position G.H5.23. Indeed, leucine could not be substituted by other amino acids in Gα13 without almost complete loss of GPR35 coupling. The critical importance of leucine at G.H5.23 for GPR35-G protein interaction was further demonstrated by introduction of this leucine into Gαq , resulting in the gain of coupling to GPR35. These studies demonstrate that Gα13 is markedly the most effective G protein for interaction with GPR35 and that selection between Gα13 and Gα12 is dictated largely by a single conservative amino acid variation.-Mackenzie, A. E., Quon, T., Lin, L.-C., Hauser, A. S., Jenkins, L., Inoue, A., Tobin, A. B., Gloriam, D. E., Hudson, B. D., Milligan, G. Receptor selectivity between the G proteins Gα12 and Gα13 is defined by a single leucine-to-isoleucine variation.- Published
- 2019
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41. Evidence for the Existence of a CXCL17 Receptor Distinct from GPR35.
- Author
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Binti Mohd Amir NAS, Mackenzie AE, Jenkins L, Boustani K, Hillier MC, Tsuchiya T, Milligan G, and Pease JE
- Subjects
- Animals, Calcium Signaling, Chemokines, CXC genetics, Chemotaxis, Endocytosis, Humans, Immunity, Innate, Mice, Receptors, G-Protein-Coupled genetics, Signal Transduction, THP-1 Cells, beta-Arrestins metabolism, Chemokines, CXC metabolism, Monocytes physiology, Receptors, G-Protein-Coupled metabolism
- Abstract
The chemokine CXCL17 is associated with the innate response in mucosal tissues but is poorly characterized. Similarly, the G protein-coupled receptor GPR35, expressed by monocytes and mast cells, has been implicated in the immune response, although its precise role is ill-defined. A recent manuscript reported that GPR35 was able to signal in response to CXCL17, which we set out to confirm in this study. GPR35 was readily expressed using transfection systems but failed to signal in response to CXCL17 in assays of β-arrestin recruitment, inositol phosphate production, calcium flux, and receptor endocytosis. Similarly, in chemotaxis assays, GPR35 did not confirm sensitivity to a range of CXCL17 concentrations above that observed in the parental cell line. We subsequently employed a real time chemotaxis assay (TAXIScan) to investigate the migratory responses of human monocytes and the monocytic cell line THP-1 to a gradient of CXCL17. Freshly isolated human monocytes displayed no obvious migration to CXCL17. Resting THP-1 cells showed a trend toward directional migration along a CXCL17 gradient, which was significantly enhanced by overnight incubation with PGE
2 However, pretreatment of PGE2 -treated THP-1 cells with the well-characterized GPR35 antagonist ML145 did not significantly impair their migratory responses to CXCL17 gradient. CXCL17 was susceptible to cleavage with chymase, although this had little effect its ability to recruit THP-1 cells. We therefore conclude that GPR35 is unlikely to be a bona fide receptor for CXCL17 and that THP-1 cells express an as yet unidentified receptor for CXCL17., (Copyright © 2018 The Authors.)- Published
- 2018
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42. The emerging pharmacology and function of GPR35 in the nervous system.
- Author
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Mackenzie AE and Milligan G
- Subjects
- Animals, Central Nervous System drug effects, Humans, Receptors, G-Protein-Coupled agonists, Receptors, G-Protein-Coupled antagonists & inhibitors, Receptors, G-Protein-Coupled genetics, Central Nervous System metabolism, Receptors, G-Protein-Coupled metabolism
- Abstract
G protein-coupled receptor 35 (GPR35) is an orphan G protein-coupled receptor (GPCR) that can be activated by kynurenic acid at high micromolar concentrations. A previously unappreciated mechanism of action of GPR35 has emerged as a Gα
i/o -coupled inhibitor of synaptic transmission, a finding that has significant implications for the accepted role of kynurenic acid as a broad-spectrum antagonist of the NMDA, AMPA/kainite and α7 nicotinic receptors. In conjunction with previous findings that link agonism of GPR35 with significant reduction in nociceptive pain, GPR35 has emerged as a potential effector of regulation of mechanical sensitivity and analgesia of the Ret tyrosine kinase, and as a receptor involved in the transmission of anti-inflammatory effects of aspirin- potentially through affecting leucocyte rolling, adhesion and extravasation. Single nucleotide polymorphisms of GPR35 have linked this receptor to coronary artery calcification, inflammatory bowel disease and primary sclerosing cholangitis, while chromosomal aberrations of the 2q37.3 locus and altered copy number of GPR35 have been linked with autism, Albight's hereditary osteodystrophy-like syndrome, and congenital malformations, respectively. Herein, we present an update on both the pharmacology and potential function of GPR35, particularly pertaining to the nervous system. This review forms part of a special edition focussing on the role of lipid-sensing GPCRs in the nervous system. This article is part of the Special Issue entitled 'Lipid Sensing G Protein-Coupled Receptors in the CNS'., (Copyright © 2015 Elsevier Ltd. All rights reserved.)- Published
- 2017
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43. Non-equivalence of Key Positively Charged Residues of the Free Fatty Acid 2 Receptor in the Recognition and Function of Agonist Versus Antagonist Ligands.
- Author
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Sergeev E, Hansen AH, Pandey SK, MacKenzie AE, Hudson BD, Ulven T, and Milligan G
- Subjects
- Binding Sites, Binding, Competitive, Butyrates chemistry, Butyrates pharmacology, Butyric Acid pharmacology, Esters metabolism, HEK293 Cells, Humans, Kinetics, Ligands, Models, Molecular, Mutant Proteins chemistry, Mutant Proteins metabolism, Receptors, Cell Surface chemistry, Thiophenes chemistry, Thiophenes pharmacology, Tritium metabolism, Amino Acids metabolism, Receptors, Cell Surface agonists, Receptors, Cell Surface antagonists & inhibitors
- Abstract
Short chain fatty acids (SCFAs) are produced in the gut by bacterial fermentation of poorly digested carbohydrates. A key mediator of their actions is the G protein-coupled free fatty acid 2 (FFA2) receptor, and this has been suggested as a therapeutic target for the treatment of both metabolic and inflammatory diseases. However, a lack of understanding of the molecular determinants dictating how ligands bind to this receptor has hindered development. We have developed a novel radiolabeled FFA2 antagonist to probe ligand binding to FFA2, and in combination with mutagenesis and molecular modeling studies, we define how agonist and antagonist ligands interact with the receptor. Although both agonist and antagonist ligands contain negatively charged carboxylates that interact with two key positively charged arginine residues in transmembrane domains V and VII of FFA2, there are clear differences in how these interactions occur. Specifically, although agonists require interaction with both arginine residues to bind the receptor, antagonists require an interaction with only one of the two. Moreover, different chemical series of antagonist interact preferentially with different arginine residues. A homology model capable of rationalizing these observations was developed and provides a tool that will be invaluable for identifying improved FFA2 agonists and antagonists to further define function and therapeutic opportunities of this receptor., (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2016
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44. Current and emerging treatment options for spinal muscular atrophy.
- Author
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Farooq F and MacKenzie AE
- Abstract
Spinal muscular atrophy is one of the most common inherited neuromuscular conditions; our understanding of the genetic pathology and translational research coming from this insight has made significant progress over the past decade. This short review provides the background of the disease along with the bench to bedside progress of some promising treatment options to develop better understanding of the present state of the disease., Competing Interests: The authors report no conflicts of interest in this work., (© 2015 Farooq and MacKenzie.)
- Published
- 2015
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45. G protein-coupled receptor 35: an emerging target in inflammatory and cardiovascular disease.
- Author
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Divorty N, Mackenzie AE, Nicklin SA, and Milligan G
- Abstract
G protein-coupled receptor 35 (GPR35) is an orphan receptor, discovered in 1998, that has garnered interest as a potential therapeutic target through its association with a range of diseases. However, a lack of pharmacological tools and the absence of convincingly defined endogenous ligands have hampered the understanding of function necessary to exploit it therapeutically. Although several endogenous molecules can activate GPR35 none has yet been confirmed as the key endogenous ligand due to reasons that include lack of biological specificity, non-physiologically relevant potency and species ortholog selectivity. Recent advances have identified several highly potent synthetic agonists and antagonists, as well as agonists with equivalent potency at rodent and human orthologs, which will be useful as tool compounds. Homology modeling and mutagenesis studies have provided insight into the mode of ligand binding and possible reasons for the species selectivity of some ligands. Advances have also been made in determining the role of the receptor in disease. In the past, genome-wide association studies have associated GPR35 with diseases such as inflammatory bowel disease, type 2 diabetes, and coronary artery disease. More recent functional studies have implicated it in processes as diverse as heart failure and hypoxia, inflammation, pain transduction and synaptic transmission. In this review, we summarize the progress made in understanding the molecular pharmacology, downstream signaling and physiological function of GPR35, and discuss its emerging potential applications as a therapeutic target.
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- 2015
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46. G-Protein-Coupled Receptor 35 Mediates Human Saphenous Vein Vascular Smooth Muscle Cell Migration and Endothelial Cell Proliferation.
- Author
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McCallum JE, Mackenzie AE, Divorty N, Clarke C, Delles C, Milligan G, and Nicklin SA
- Subjects
- Actin Cytoskeleton metabolism, Aminosalicylic Acids pharmacology, Dose-Response Relationship, Drug, Endothelial Cells drug effects, Endothelial Cells pathology, HEK293 Cells, Humans, Hydrazones pharmacology, Muscle, Smooth, Vascular drug effects, Muscle, Smooth, Vascular pathology, Myocytes, Smooth Muscle drug effects, Myocytes, Smooth Muscle pathology, Naphthols pharmacology, Purinones pharmacology, Receptors, G-Protein-Coupled agonists, Receptors, G-Protein-Coupled antagonists & inhibitors, Receptors, G-Protein-Coupled genetics, Saphenous Vein metabolism, Saphenous Vein pathology, Signal Transduction, Thiazolidines pharmacology, Thiourea analogs & derivatives, Thiourea pharmacology, Time Factors, rho-Associated Kinases metabolism, rhoA GTP-Binding Protein metabolism, Cell Movement, Cell Proliferation, Endothelial Cells metabolism, Muscle, Smooth, Vascular metabolism, Myocytes, Smooth Muscle metabolism, Receptors, G-Protein-Coupled metabolism
- Abstract
Vascular smooth muscle cell (VSMC) migration and proliferation is central to neointima formation in vein graft failure following coronary artery bypass. However, there are currently no pharmacological interventions that prevent vein graft failure through intimal occlusion. It is hence a therapeutic target. Here, we investigated the contribution of GPR35 to human VSMC and endothelial cell (EC) migration, using a scratch-wound assay, and also the contribution to proliferation, using MTS and BrdU assays, in in vitro models using recently characterized human GPR35 ortholog-selective small-molecule agonists and antagonists. Real-time PCR studies showed GPR35 to be robustly expressed in human VSMCs and ECs. Stimulation of GPR35, with either the human-selective agonist pamoic acid or the reference agonist zaprinast, promoted VSMC migration in the scratch-wound assay. These effects were blocked by coincubation with either of the human GPR35-specific antagonists, CID-2745687 or ML-145. These GPR35-mediated effects were produced by inducing alterations in the actin cytoskeleton via the Rho A/Rho kinase signaling axis. Additionally, the agonist ligands stimulated a proliferative response in ECs. These studies highlight the potential that small molecules that stimulate or block GPR35 activity can modulate vascular proliferation and migration. These data propose GPR35 as a translational therapeutic target in vascular remodeling., (© 2016 The Author(s) Published by S. Karger AG, Basel.)
- Published
- 2015
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47. The antiallergic mast cell stabilizers lodoxamide and bufrolin as the first high and equipotent agonists of human and rat GPR35.
- Author
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MacKenzie AE, Caltabiano G, Kent TC, Jenkins L, McCallum JE, Hudson BD, Nicklin SA, Fawcett L, Markwick R, Charlton SJ, and Milligan G
- Subjects
- Animals, Cell Line, Computer Simulation, Cricetinae, Cricetulus, Humans, Mast Cells physiology, Molecular Docking Simulation, Mutation, Oxamic Acid pharmacology, Polymorphism, Single Nucleotide, Rats, Receptors, G-Protein-Coupled genetics, Anti-Allergic Agents pharmacology, Mast Cells drug effects, Oxamic Acid analogs & derivatives, Phenanthrolines pharmacology, Receptors, G-Protein-Coupled agonists
- Abstract
Lack of high potency agonists has restricted analysis of the G protein-coupled receptor GPR35. Moreover, marked variation in potency and/or affinity of current ligands between human and rodent orthologs of GPR35 has limited their productive use in rodent models of physiology. Based on the reported modest potency of the antiasthma and antiallergic ligands cromolyn disodium and nedocromil sodium, we identified the related compounds lodoxamide and bufrolin as high potency agonists of human GPR35. Unlike previously identified high potency agonists that are highly selective for human GPR35, both lodoxamide and bufrolin displayed equivalent potency at rat GPR35. Further synthetic antiallergic ligands, either sharing features of the standard surrogate agonist zaprinast, or with lodoxamide and bufrolin, were also shown to display agonism at either human or rat GPR35. Because both lodoxamide and bufrolin are symmetric di-acids, their potential mode of binding was explored via mutagenesis based on swapping between the rat and human ortholog nonconserved arginine residues within proximity of a key conserved arginine at position 3.36. Computational modeling and ligand docking predicted the contributions of different arginine residues, other than at 3.36, in human GPR35 for these two ligands and were consistent with selective loss of potency of either bufrolin or lodoxamide at distinct arginine mutants. The computational models also suggested that bufrolin and lodoxamide would display reduced potency at a low-frequency human GPR35 single nucleotide polymorphism. This prediction was confirmed experimentally.
- Published
- 2014
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48. The pharmacology of TUG-891, a potent and selective agonist of the free fatty acid receptor 4 (FFA4/GPR120), demonstrates both potential opportunity and possible challenges to therapeutic agonism.
- Author
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Hudson BD, Shimpukade B, Mackenzie AE, Butcher AJ, Pediani JD, Christiansen E, Heathcote H, Tobin AB, Ulven T, and Milligan G
- Subjects
- 3T3-L1 Cells, Animals, Arrestins physiology, Calcium metabolism, Extracellular Signal-Regulated MAP Kinases metabolism, GTP-Binding Protein alpha Subunits, Gq-G11 physiology, Glucose metabolism, HEK293 Cells, Humans, Mice, Phosphorylation, beta-Arrestin 1, beta-Arrestin 2, beta-Arrestins, Biphenyl Compounds pharmacology, Phenylpropionates pharmacology, Receptors, G-Protein-Coupled agonists
- Abstract
TUG-891 [3-(4-((4-fluoro-4'-methyl-[1,1'-biphenyl]-2-yl)methoxy)phenyl)propanoic acid] was recently described as a potent and selective agonist for the long chain free fatty acid (LCFA) receptor 4 (FFA4; previously G protein-coupled receptor 120, or GPR120). Herein, we have used TUG-891 to further define the function of FFA4 and used this compound in proof of principle studies to indicate the therapeutic potential of this receptor. TUG-891 displayed similar signaling properties to the LCFA α-linolenic acid at human FFA4 across various assay end points, including stimulation of Ca²⁺ mobilization, β-arrestin-1 and β-arrestin-2 recruitment, and extracellular signal-regulated kinase phosphorylation. Activation of human FFA4 by TUG-891 also resulted in rapid phosphorylation and internalization of the receptor. While these latter events were associated with desensitization of the FFA4 signaling response, removal of TUG-891 allowed both rapid recycling of FFA4 back to the cell surface and resensitization of the FFA4 Ca²⁺ signaling response. TUG-891 was also a potent agonist of mouse FFA4, but it showed only limited selectivity over mouse FFA1, complicating its use in vivo in this species. Pharmacologic dissection of responses to TUG-891 in model murine cell systems indicated that activation of FFA4 was able to mimic many potentially beneficial therapeutic properties previously reported for LCFAs, including stimulating glucagon-like peptide-1 secretion from enteroendocrine cells, enhancing glucose uptake in 3T3-L1 adipocytes, and inhibiting release of proinflammatory mediators from RAW264.7 macrophages, which suggests promise for FFA4 as a therapeutic target for type 2 diabetes and obesity. Together, these results demonstrate both potential but also significant challenges that still need to be overcome to therapeutically target FFA4.
- Published
- 2013
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49. Rare-disease genetics in the era of next-generation sequencing: discovery to translation.
- Author
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Boycott KM, Vanstone MR, Bulman DE, and MacKenzie AE
- Subjects
- Genetic Predisposition to Disease, Genetic Testing, Genetics, Medical, Genome-Wide Association Study, Humans, Mutation, Rare Diseases therapy, Sequence Analysis, DNA, Genome, Human genetics, High-Throughput Nucleotide Sequencing trends, Rare Diseases genetics
- Abstract
Work over the past 25 years has resulted in the identification of genes responsible for ~50% of the estimated 7,000 rare monogenic diseases, and it is predicted that most of the remaining disease-causing genes will be identified by the year 2020, and probably sooner. This marked acceleration is the result of dramatic improvements in DNA-sequencing technologies and the associated analyses. We examine the rapid maturation of rare-disease genetic analysis and successful strategies for gene identification. We highlight the impact of discovering rare-disease-causing genes, from clinical diagnostics to insights gained into biological mechanisms and common diseases. Last, we explore the increasing therapeutic opportunities and challenges that the resulting expansion of the 'atlas' of human genetic pathology will bring.
- Published
- 2013
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50. Defining the molecular basis for the first potent and selective orthosteric agonists of the FFA2 free fatty acid receptor.
- Author
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Hudson BD, Due-Hansen ME, Christiansen E, Hansen AM, Mackenzie AE, Murdoch H, Pandey SK, Ward RJ, Marquez R, Tikhonova IG, Ulven T, and Milligan G
- Subjects
- Adipocytes drug effects, Adipocytes metabolism, Allosteric Regulation, Amino Acid Motifs, Amino Acid Substitution, Animals, Benzeneacetamides pharmacology, Binding Sites, Cyclopropanes chemistry, Enteroendocrine Cells metabolism, Glucagon-Like Peptide 1 metabolism, Guanosine 5'-O-(3-Thiotriphosphate) metabolism, HEK293 Cells, Humans, Lipolysis drug effects, Mice, Models, Molecular, Mutagenesis, Site-Directed, Protein Binding, Protein Structure, Tertiary, Rats, Receptors, Cell Surface chemistry, Receptors, Cell Surface genetics, Receptors, Cell Surface metabolism, Thiazoles chemistry, Butyrates pharmacology, Cyclopropanes pharmacology, Receptors, Cell Surface agonists, Thiazoles pharmacology
- Abstract
FFA2 is a G protein-coupled receptor that responds to short chain fatty acids and has generated interest as a therapeutic target for metabolic and inflammatory conditions. However, definition of its functions has been slowed by a dearth of selective ligands that can distinguish it from the closely related FFA3. At present, the only selective ligands described for FFA2 suffer from poor potency, altered signaling due to allosteric modes of action, or a lack of function at non-human orthologs of the receptor. To address the need for novel selective ligands, we synthesized two compounds potentially having FFA2 activity and examined the molecular basis of their function. These compounds were confirmed to be potent and selective orthosteric FFA2 agonists. A combination of ligand structure-activity relationship, pharmacological analysis, homology modeling, species ortholog comparisons, and mutagenesis studies were then employed to define the molecular basis of selectivity and function of these ligands. From this, we identified key residues within both extracellular loop 2 and the transmembrane domain regions of FFA2 critical for ligand function. One of these ligands was active with reasonable potency at rodent orthologs of FFA2 and demonstrated the role of FFA2 in inhibition of lipolysis and glucagon-like peptide-1 secretion in murine-derived 3T3-L1 and STC-1 cell lines, respectively. Together, these findings describe the first potent and selective FFA2 orthosteric agonists and demonstrate key aspects of ligand interaction within the binding site of FFA2 that will be invaluable in future ligand development at this receptor.
- Published
- 2013
- Full Text
- View/download PDF
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