Publications by authors named "M W Schorr"

90 Publications

Methemoglobinemia in a 28-year-old woman treated with dapsone.

CMAJ 2022 Aug;194(30):E1062-E1065

Schulich School of Medicine and Dentistry (Jacob, Schorr, Moist), Western University, London, Ont.; Health Research Methodology (Schorr), Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ont.; Kidney Clinical Research Unit (Moist), Division of Nephrology, Department of Medicine Western University, London, Ont.

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http://dx.doi.org/10.1503/cmaj.212015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9365429PMC
August 2022

Cognitive Impairment Early After Initiating Maintenance Hemodialysis: A Cross Sectional Study.

Front Neurol 2022 15;13:719208. Epub 2022 Mar 15.

Division of Nephrology, Department of Medicine, London Health Sciences Centre, London, ON, Canada.

Background: Abnormalities in cognitive function are almost universal in patients receiving hemodialysis (HD) and are associated with worse quality of life, impaired decision making, increased healthcare utilization and mortality. While cognitive impairment in the HD population is increasingly recognized, it is unclear how quickly it develops after starting HD.

Methods: This was a cross-sectional study of a cohort of low dialysis vintage HD patients (<12 months). We used the validated Cambridge Brain Science (CBS) battery of web-based tests to evaluate cognition compared to age- and sex matched controls across three cognitive domains: verbal processing, reasoning and short-term memory.

Results: Forty-nine HD patients were included in this study; 43 completed the full battery of tests. The average scores for HD patients were consistently below the age and sex-matched controls. Fifty-five percent of HD patients had cognitive impairment in verbal skills, 43% in reasoning and 18% in short-term memory.

Conclusions: There is a high prevalence of CI evident early after starting HD, with the largest deficits seen in reasoning and verbal processing. These deficits may be attributable to the HD treatment itself. Further studies are needed to characterize the natural history of CI in this patient population and to test interventions aimed at preventing or slowing its progression.
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http://dx.doi.org/10.3389/fneur.2022.719208DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8964944PMC
March 2022

Dissection of Barrier Dysfunction in Organoid-Derived Human Intestinal Epithelia Induced by Giardia duodenalis.

Gastroenterology 2022 03 23;162(3):844-858. Epub 2021 Nov 23.

Department of Infectious Diseases, Unit 16 Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institute, Berlin, Germany. Electronic address:

Background & Aims: The protozoa Giardia duodenalis is a major cause of gastrointestinal illness worldwide, but underlying pathophysiological mechanisms remain obscure, partly due to the absence of adequate cellular models. We aimed at overcoming these limitations and recapitulating the authentic series of pathogenic events in the primary human duodenal tissue by using the human organoid system.

Methods: We established a compartmentalized cellular transwell system with electrophysiological and barrier properties akin to duodenal mucosa and dissected the events leading to G. duodenalis-induced barrier breakdown by functional analysis of transcriptional, electrophysiological, and tight junction components.

Results: Organoid-derived cell layers of different donors showed a time- and parasite load-dependent leak flux indicated by collapse of the epithelial barrier upon G. duodenalis infection. Gene set enrichment analysis suggested major expression changes, including gene sets contributing to ion transport and tight junction structure. Solute carrier family 12 member 2 and cystic fibrosis transmembrane conductance regulator-dependent chloride secretion was reduced early after infection, while changes in the tight junction composition, localization, and structural organization occurred later as revealed by immunofluorescence analysis and freeze fracture electron microscopy. Functionally, barrier loss was linked to the adenosine 3',5'-cyclic monophosphate (cAMP)/protein kinase A-cAMP response element-binding protein signaling pathway.

Conclusions: Data suggest a previously unknown sequence of events culminating in intestinal barrier dysfunction upon G. duodenalis infection during which alterations of cellular ion transport were followed by breakdown of the tight junctional complex and loss of epithelial integrity, events involving a cAMP/protein kinase A-cAMP response element-binding protein mechanism. These findings and the newly established organoid-derived model to study G. duodenalis infection may help to explore new options for intervening with disease and infection, in particular relevant for chronic cases of giardiasis.
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http://dx.doi.org/10.1053/j.gastro.2021.11.022DOI Listing
March 2022

Association between childhood trauma, parental bonding and antisocial personality disorder in adulthood: A machine learning approach.

Psychiatry Res 2021 10 29;304:114082. Epub 2021 Jun 29.

Department of Psychiatry and Legal Medicine, School of Medicine, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Department of Psychiatry(,) Graduate Program in Psychiatry and Behavioral Sciences, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Research Laboratory in Psychodynamic Psychiatry, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.

Childhood trauma (CT) and parental bonding (PB) have been correlated with later antisocial personality disorder (ASPD). Aiming to better understand this complex interaction we analyzed the data from a cross-sectional study that evaluated 346 male inpatient cocaine users, using both traditional statistical analysis and machine learning (ML) approaches. Childhood Trauma Questionnaire (CTQ), Parental Bonding Instrument (PBI), and Mini International Neuropsychiatric Interview (MINI) were applied. We found a markedly higher prevalence of mental illness in the ASPD group. The ML method and the traditional analysis showed that emotional and physical abuse were the factors with the strongest relationship with ASPD. Also, there were discrepancies between the findings of both methods regarding physical neglect and paternal care. Although this study does not allow definitive answers in this matter, we do propose that these two methods can aid in better comprehending how multiple variables interact with each other in the development of psychological disorders.
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http://dx.doi.org/10.1016/j.psychres.2021.114082DOI Listing
October 2021

A Higher Concentration of Dialysate Magnesium to Reduce the Frequency of Muscle Cramps: A Narrative Review.

Can J Kidney Health Dis 2020 22;7:2054358120964078. Epub 2020 Oct 22.

Division of Nephrology, Department of Medicine, Health Sciences Centre, University of Calgary, Calgary, AB, Canada.

Purpose Of Review: Strategies to mitigate muscle cramps are a top research priority for patients receiving hemodialysis. As hypomagnesemia is a possible risk factor for cramping, we reviewed the literature to better understand the physiology of cramping as well as the epidemiology of hypomagnesemia and muscle cramps. We also sought to review the evidence from interventional studies on the effect of oral and dialysate magnesium-based therapies on muscle cramps.

Sources Of Information: Peer-reviewed articles.

Methods: We searched for relevant articles in major bibliographic databases including MEDLINE and EMBASE. The methodological quality of interventional studies was assessed using a modified version of the Downs and Blacks criteria checklist.

Key Findings: The etiology of muscle cramps in patients receiving hemodialysis is poorly understood and there are no clear evidence-based prevention or treatment strategies. Several factors may play a role including a low concentration of serum magnesium. The prevalence of hypomagnesemia (concentration of <0.7 mmol/L) in patients receiving hemodialysis ranges from 10% to 20%. Causes of hypomagnesemia include a low dietary intake of magnesium, use of medications that inhibit magnesium absorption (eg, proton pump inhibitors), increased magnesium excretion (eg, high-dose loop diuretics), and a low concentration of dialysate magnesium. Dialysate magnesium concentrations of ≤0.5 mmol/L may be associated with a decrease in serum magnesium concentration over time. Preliminary evidence from observational and interventional studies suggests a higher dialysate magnesium concentration will raise serum magnesium concentrations and may reduce the frequency and severity of muscle cramps. However, the quality of evidence supporting this benefit is limited, and larger, multicenter clinical trials are needed to further determine if magnesium-based therapy can reduce muscle cramps in patients receiving hemodialysis. In studies conducted to date, increasing the concentration of dialysate magnesium appears to be well-tolerated and is associated with a low risk of symptomatic hypermagnesemia.

Limitations: Few interventional studies have examined the effect of magnesium-based therapy on muscle cramps in patients receiving hemodialysis and most were nonrandomized, pre-post study designs.
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http://dx.doi.org/10.1177/2054358120964078DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7585892PMC
October 2020
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