Salutogenesis Meeting Places: The Global Working Group, the Center, and the Society on Salutogenesis

In this chapter, the author provides the reader with a useful description of Salutogenesis meeting places. These are the Society for Theory and Research on Salutogenesis (STARS) and the Global Working Group on Salutogenesis (GWG-Sal) of the International Union for Health Promotion and Education (IUHPE). The author also provides information about the Center on Salutogenesis at the University of Zürich in Switzerland. The Center is the host organization of both meeting places. The key message of this chapter is that one’s involvement in STARS will extend one’s professional network, open new avenues for research and publishing, and help achieve a vision of “salutogenesis for thriving societies.” The reader wanting to connect more directly to a global salutogenesis network will find this chapter to be of great practical value.

Mieczysław Wolfke - a pioneer of holography

Receiving the Nobel Prize in 1971 for the invention and development of the holographic method, Dennis Gabor mentioned Mieczysław Wolfke as the person who proposed this method as early as 1920 (which he did not know, independently making the same discovery). This article describes the history of Wolfke's pioneering work and tries to recreate the thought process that led to it - starting with the task of supplementing and verifying the diffraction grating theory proposed by Ernst Abbe, which he carried out as part of his doctorate at the University of Wrocław and habilitation at the University of Zurich and the Swiss Federal Institute of Technology in Zurich.. Full Text: PDF ReferencesW. Łaniecki, Kwartalnik Historii Nauki i Techniki, 21, 545-553 (1976). DirectLink W. Keesom, "Solidification of Helium", Nature 118, 81 (1926). CrossRef W. Keesom, M. Wolfke, "Two liquid states of helium", Konink. Akad. Wetensch. Amsterdam, Proc, 31(190b), 90-94 (1928).W. Keesom, Helium (Elsevier, Amsterdam 1942).E. Abbe, Die Lehre von der Bildentstehung im Mikroskop (F. Vieweg, Braunschweig 1910). CrossRef R. Torge, Postępy Fizyki, 53, 201-210 (2002). CrossRef A.Kiejna, Kwartalnik Historii Nauki i Techniki, 48, 7 (2003). DirectLink M. Wolfke, "Über die Abbildung eines Gitters bei künstlicher Begrenzung", Ann Phys. 339, 277 (1911). CrossRef M. Wolfke, Prace matematyczno-fizyczne, 22, 135 (1911). DirectLink M. Wolfke, "Über die Abbildung eines Gitters bei asymmetrischer Abblendung", Ann Phys. 342, 96 (1912). CrossRef M. Wolfke, "Über die Abbildung eines durchlässigen Gitters", Ann Phys. 342, 797 (1912). CrossRef M. Wolfke, "Zur Abbildung eines durchlässigen Gitters", Ann Phys. 343, 385 (1912). CrossRef K. Petelczyc, E. Kędzierska, Mieczysław Wolfke. Gdyby mi dali choć pół miliona… (OWPW, Warszawa 2018). DirectLink L.A. Aslanov, G.V. Fetisov, J.A.K. Howard, "Crystallographic Instrumentation", Oxford (1998). CrossRef M. Wolfke, Wiadomości matematyczne 17, 1 (1913). DirectLink M. Wolfke, "Allgemeine Abbildungstheorie selbstleuchtender und nicht selbstleuchtender Objekte", Ann Phys. 344, 569 (1912). CrossRef M. Wolfke, "Über die Abbildung eines Gitters außerhalb der Einstellebene", Ann Phys. 345, 194 (1913). CrossRef M. Wolfke, Verhandlungen der DPG, 15, 1123 (1913).M. Wolfke, Verhandlungen der DPG, 15, 1215 (1913).M. Wolfke, Verhandlungen der DPG, 16, 4 (1914).M. Wolfke, "Fragen zur Pathologie des menschlichen Oedems", Physikalische Zeitschrift, 22, 375 (1921). CrossRef Akta osobowe - Wolfke Mieczysław, Archiwum Akt Nowych sygn. 2/14/0/6/6638, WarszawaM. Wolfke, Physikalische Zeitschrift, 21, 495 (1920). DirectLink S. Lundqvist, Nobel Lectures, Physics 1971-1980 (World Scientific Publishing Co. Singapore 1992) CrossRef

BIOLOGICAL SESSION“THE IMPORTANCE OF G. GAMOW'S IDEAS FOR BIOLOGY OF THE 21st CENTURY” AT THE XXI GAMOW INTERNATIONAL ASTRONOMICAL CONFERENCE-SCHOOL IN ODESSA (15-21 AUGUST, 2021)

Третій рік поспіль в межах Гамовської конференції працює Біологічна секція: «Важливість ідей Г.А. Гамова для біології 21-ого століття», організація якої викликана великою повагою до особистості вченого Георгія Антоновича Гамова, наукові інтереси якого об’єднали астрофізику, космологію та молекулярну біологію. Цього року Біологічна секція працювала в режимі on-line 17.08.2021. Роботу секції розпочали з виступу професора Тобіуса Дельбрюка (Institute of Neuroinformatics – ETH and University of Zurich, Zurich, Switzerland), сина видатного фізика, Нобелевського лауреата Макса Дельбрюка (в певний період товариша Г.А. Гамова). Професор Тобіус Дельбрюк назвав свою доповідь – "Out of this world: Recounting Max's Delbruck memories of George Gamow”. Ця доповідь, присвячена феноменальній особистості Г.А. Гамова, придала засіданню біологічної секції емоційну атмосферу наближення до великих ідей, що надали і зараз надають поштовх для розвитку молекулярної біології. Значну зацікавленість учасників секції викликала доповідь Dr. V.N. Korzun (KWS SAAT SE & Co. KGaA (м. Айнбек, Німеччина) «Applications of genetic and genomic research in cereals», що продемонструвала впровадження в селекційний процес сучасних молекулярно-генетичних технологій. З доповіддю «DNA-protein interactions as a tool of synthetic biology», що присвячена високо технологічним розробкам зі створення біосенсорів науково-виробничою фіромою Explogen LLC (EXG) (м. Львів, Україна) виступив к.б.н. Ю. Ребець. Наступна пленарна доповідь «Using the G.A. Gamow’s ideas for molecular genetic diagnostics of infectious and somatic human diseases at the current stage of medical development» була представлена білоруськими вченими, а саме професор С.А. Касцьюк розповіла про молекулярно-генетичні дослідження, що виконуються в Білоруській медичній академії післядипломної освіти. Dr. Yu. Monchak з McGill University (м. Монреаль, Канада) також представив доповідь присвячену впровадженню ДНК-технологій в діагностику патології людини ˗ «Targeted therapy, DNA sequence and the race against neoplasia». Ця доповідь викликала велику зацікавленість учасників біологічної секції. Молоді науковці Іщенко О.О., Жарікова Д.О., Роман І.І., Доля Б., Рошка Н.М., Чубик І.Ю., Попович Ю.А., Топораш М.К., Пидюра М.О. – доктори філософії з біології, кандидати наук, аспіранти, що займаються дослідженнями в галузі молекулярної біології представили дев’ять доповідей, що відбивають результати виконаних досліджень у низці провідних університетів нашої країни, а саме у Львівському національному університеті ім. І. Франка, у Одеському національному університеті імені І.І. Мечникова, у Чернівецькому національному університеті ім. Юрія Федьковича та ДУ «Інституті харчової біотехнології та Геноміки» (м. Київ). Представлені доповіді викликали жвавий інтерес, а формат on-line дозволів об’єднати у роботі секції понад 35 учасників з різних країн ˗ України, Білорусі, Швейцарії, Німеччини, Канади і Казахстану.

Theological Empowerment of Lay Leaders: A Citizen Science Project in Switzerland and Austria

The present research project addresses the question of how the theological literacy and agency of volunteer church leaders can be fostered so that cooperative church leadership can be achieved. The Protestant Churches of the Canton of St. Gallen (Switzerland) and Austria, together with the Centre for Church Development of the University of Zurich, designed a participatory research process. The aim was to increase the communicative and participative competence of volunteers. Together, through a creative and discursive process, the foundations, educational processes and tools necessary for theological empowerment were developed with the volunteer church leaders. The cooperative project combines research and practice in the sense that practitioners were actively involved in generating, evaluating and discussing the data. In addition, in this project we found ways to continue participatory research – for example through online discourse formats – and thus not lose the essence of such research in times of covid-19.

A historical vertebrate collection from the Middle Miocene of the Peruvian Amazon

The Miocene aquatic and terrestrial fossil record from western Amazonia constitute a clear evidence of the palaeoenvironmental diversity that prevailed in the area, prior to the establishment of the Amazon River drainage. During the Miocene, the region was characterized by a freshwater megawetland basin, influenced by episodic shallow-marine incursions. A fossil vertebrate collection from the middle Miocene strata of the Pebas Formation is here studied and described. This historical collection was recovered in 1912 along the banks of the Itaya River (Iquitos, Peru), during a scientific expedition led by two scientists of the University of Zurich, Hans Bluntschli and Bernhard Peyer. Our findings include a total of 34 taxa, including stingrays, bony fishes, turtles, snakes, crocodylians, and lizards. Fishes are the most abundant group in the assemblage (~ 23 taxa), including the first fossil record of the freshwater serrasalmids Serrasalmus, and Mylossoma, and the hemiodontid Hemiodus for the Pebas system, with the latter representing the first fossil be discovered for the entire Hemiodontidae. The presence of a representative of Colubroidea in the middle Miocene of Iquitos supports the hypothesis of arrival and dispersal of these snakes into South America earlier than previously expected. This fossil assemblage sheds light on the palaeoenvironments, and the geographical/temporal range of several aquatic/terrestrial lineages inhabiting the Amazonian region.

Anti-CD117 CAR T Cells Incorporating a Safety Switch Eradicate Acute Myeloid Leukemia and Deplete Human Hematopoietic Stem Cells

Introduction Acute Myeloid Leukemia (AML) arises from the accumulation of mutations within the hematopoietic stem and progenitor cells (HSPC), leading to the emergence of a population of malignant leukemia-initiating cells (LIC). AML-LICs maintain high phenotypic similarity with their cells-of-origin and can cause post-treatment relapse. Immunotherapy with chimeric antigen receptor (CAR) T cells is an innovative approach to tackle cancer via surface-expressed cancer-associated antigens. We recently proposed the use of CAR T cells specific for the CD117 antigen to deplete LIC and replace HSPC by allogeneic hematopoietic stem cell transplantation (HSCT) (Myburgh R et al. Leukemia 2020). This concept implies early termination of CAR T-cell activity to prevent subsequent graft rejection. Here, we exploit a non-viral technology for the generation of anti-CD117 CAR T cells incorporating a safety switch. Methods We designed a Sleeping Beauty (SB) transposon vector that includes the inducible Caspase 9 (iC9) switch and the anti-CD117CAR, separated by a 2A peptide. SB allows the generation of CAR T cells with potent anti-leukemic activity (Magnani CF et al. J Clin Invest. 2020). The vector has an optimized donor vector architecture and allows for the stoichiometric expression of the two transgenes. iC9 allows for rapid termination of CAR T cells by activation of the apoptotic pathway in case of treatment with a small molecule that acts as a chemical inducer of dimerization (CID). The hyperactive SB100X transposase, supplied as plasmid DNA or mRNA, catalyzes transgene integration. As an alternative approach, we used mRNA encoding an anti-CD117 CAR in human T cells. Results With the purpose of transduction optimization, we compared total PBMC and selected T cells as starting material in the presence of different concentrations of plasmids or mRNA. The procedure of generating CAR T cells with SB did not affect T cell memory differentiation but increased the CD8/CD4 proportion compared to non-transduced (NT) cells (75.63% vs. 41.63%, p= 0.0124). Based on higher transduction efficiency and favored in vitro expansion, we defined the lead protocol (selected T cells, PT4:SB100X plasmid 3:1 ratio, or PT4:SB100X mRNA 1:2 ratio). CAR T cells had a high level of viability, retained a high proportion of naïve-like (mean 36.38%, SEM 8.80) and T stem cell memory populations (mean 39.21%, SEM 8.43), and showed low levels of the exhaustion markers PD-1 (mean 2.21%, SEM 1.04), LAG3 (mean 61.20%, SEM 9.61), and TIM3 (mean 35.72%, SEM 10.79). Anti-CD117 CAR T cells exhibited potent cytotoxicity against the AML cell line MOLM-14, transduced and sorted to express human CD117, luciferase, and GFP. The addition of 200nM of the CID to cultures of anti-CD117 CAR T cells induced apoptosis of transduced CAR T cells within 24h but had no effect on the viability of NT cells. Anti-CD117 CAR T cells mediated depletion of CD117+ MOLM-14 cells in vivo, leading to a significant survival advantage compared to mice treated with NT cells (median overall survival for NT= 22.5 days vs. SB= not reached, p= 0.0122, Mantel-Cox). Notably, SB-transduced CAR T cells were as efficient as CAR T cells transduced with lentiviral vectors. In NSG mice reconstituted with human CD34+ cord blood cells, anti-CD117 CAR T cells were able to achieve complete CD117+ HSPC depletion. Treatment with a combination of CID and anti-thymocyte globulin (ATG) eliminated anti-CD117 CAR T cells and T cells of the previous transplant donor. Finally, transient expression of anti-CD117 CAR by mRNA conferred T cells the ability to kill CD117+ targets throughout 72 hours post mRNA electroporation. The cytotoxic activity decreased over time as mRNA-electroporated CAR T cells proliferate and lose CAR expression upon 3-5 divisions. Treatment of humanized NSG mice with two subsequent doses of anti-CD117 CAR mRNA T cells resulted in HSPC depletion. Conclusions Anti-CD117 CAR T cells engineered with the SB vector showed anti-leukemic activity and completely depleted healthy HSPC in vivo. iC9 transgene induced CAR T cell apoptosis and allowed rapid CAR T cell depletion that alternatively also could be achieved with mRNA electroporation of the anti-CD117 CAR. The ability to control CAR T cell pharmacokinetic properties is attractive to enable subsequent HSCT and to terminate unexpected toxicities. Anti-CD117 CAR T cells could be used prior to HSCT in refractory or minimal residual disease AML. Disclosures Myburgh: University of Zurich: Patents & Royalties: CD117xCD3 TEA. Shizuru: Forty seven Inc: Other: Inventor on a patent licenses by Forty Seven. Forty seven was acquired by Gilead in 2020; Jasper Therapeutics, Inc.: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Chair of scientific advisory board. Neri: Philogen S.p.A.: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: Multiple patents on vascular targeting; ETH Zurich: Patents & Royalties: CD117xCD3 TEA. Manz: CDR-Life Inc: Consultancy, Current holder of stock options in a privately-held company; University of Zurich: Patents & Royalties: CD117xCD3 TEA.

A Bispecific Antibody Targeting CD117 and CD3 Enables T Cell Mediated Killing of CD117-Expressing Healthy and Malignant Hematopoietic Cells

INTRODUCTION: Hematopoietic stem and progenitor cells (HSPCs) support life-long hematopoiesis. A single HSPC can also be at the origin of hematological malignancies, such as Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS). Allogeneic HSCT with the intent to eliminate recipient AML or MDS and at the same time replace recipient HSPC with donor-HSPC and immune cells is a life-saving therapeutic option for many patients. However, chemotherapy (and sometimes in addition gamma-irradiation based conditioning regiments) prior to HSCT are associated with substantial toxicity. Thus, due to benefit-outweighing treatment-related toxicity and mortality, frail, multi-morbid and elderly patients are usually excluded from potentially curative allo-HSCT approaches. For these reasons, more selective preconditioning strategies, leading to residual AML/MDS elimination and creating "space" for incoming HSPCs, are required. Selective targeting of CD117 with monoclonal antibodies has been proposed as a strategy to remove endogenous HSPCs, enabling an effective but mild preconditioning. However, specific conditioning of AML and MDS patients, prior to HSCT, might require a more potent effector cell type. We hypothesized that a CD117 and CD3 binding, T cell engaging and activating antibody construct (CD117xCD3 TEA) with a short half-life might be an ideal means to selectively eliminate CD117-expressing healthy HSPCs and residual CD117-expressing AML or MDS cells prior to allo-HSCT. METHODS: We cloned and expressed CD117xCD3 TEA in tandem scFv format and produced it by transient gene expression in Chinese hamster ovary cells (CHO-S). The fusion proteins were purified to homogeneity by protein A affinity chromatography. We derived target cell lines with varying surface levels of CD117 (high, medium and low) from CD117 negative parental cell lines HL-60 and MOLM-14 (Myburgh et al., Leukemia, 2020). To assess T cell mediated killing of target cells, we mixed them with human T cells (purified and enriched after negative selection) at varying Effector-to-Target (E:T) cell ratios and added CD117xCD3 TEA at different concentrations. The mixture was incubated and specific killing was quantified via flow cytometry at different time-points. RESULTS: In order to characterize the biocidal properties of CD117xCD3 TEA, we performed in vitro killing experiments against cell lines, HSCPs from healthy donors and blast cells from AML patients. A dose-dependent in vitro killing of the cell lines was observed in the presence of various concentrations of CD117xCD3 TEA and of human T cells at an E:T cell ratio of 10:1 after 24h. The HL60 CD117 high cell line was efficiently lysed (~90%) at 100 ng/ml of CD117xCD3 TEA, corresponding to ~1.8 nM. In similar experiments with different E:T cell ratios, we observed that both HL60 CD117 high and CD117 medium cells could be quantitatively killed at E:T ratios as low as 1:1, while the killing of CD117 low cells required a higher density of T cells. The biocidal effect on non-transduced HL60 cells was negligibly low, confirming the requirement of a simultaneous engagement of CD117 and CD3 for specific killing. We repeated the same experiment with an engineered MOLM14 cell line, which also expressed CD117 at comparable high levels, incubating the target cell line with human T cells at an E:T of 1:1 for 24, 48 or 72, 120 or 192 hours. Complete killing of the target cell line was achieved at 120 and 192 hours and after supplemental addition of T cells and CD117xCD3 TEA at 72 hours (see example figure). Experiments with primary cells (HSPCs from healthy donors or blast cells from AML patients) at an E:T of 1:1 confirmed specific killing of target cells in an antigen-density- and concentration-dependent manner after 48h. CONCLUSIONS: We have generated a novel bispecific antibody, which binds to human CD117 (expressed on HSCPs and AML/MDS blast cells) and to CD3 (expressed on T cells), which we term CD117xCD3 TEA. The antibody induces selective T cell-mediated killing of cell lines with different surface levels of CD117, as well as of healthy HSPCs and primary human AML cells. Thus, the newly generated CD117xCD3 TEA might be developed clinically in order to erradicate residual AML/MDS and at the same time serve as a milder preconditioning approach prior to allo-HSCT in frail AML/MDS patients. Figure 1 Figure 1. Disclosures Kiefer: ETH Zurich: Current Employment, Patents & Royalties: CD117xCD3 TEA. Myburgh: University of Zurich: Patents & Royalties: CD117xCD3 TEA. Guggisberg: F. Hoffmann-La Roche AG: Current Employment. Abdelmotaleb: F. Hoffmann-La Roche AG: Current Employment. Mock: Philogen S.p.A.: Current Employment. Neri: Philogen S.p.A.: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: Multiple patents on vascular targeting; ETH Zurich: Patents & Royalties: CD117xCD3 TEA. Manz: University of Zurich: Patents & Royalties: CD117xCD3 TEA; CDR-Life Inc: Consultancy, Current holder of stock options in a privately-held company.

CD117 As an Immunotherapeutic Target in Advanced Forms of Mastocytosis

Mastocytosis is a malignant disease resulting from oncogenic transformed mast cells. Up to 80% of malignant cells harbor a D816V mutation in the KIT-receptor (CD117), leading to constitutive kinase activation and proliferation and survival of mast cells. Advanced forms of mastocytosis (aggressive systemic mastocytosis: ASM, systemic mastocytosis with associated hematological disease: SM-AHN, mast cell leukemia: MCL) present as a therapeutic challenge. Although the recently approved poly tyrosine kinase inhibitor Midostaurin provides some improvement, the median overall survival ranges from 3.5 years (ASM) to less than six months (MCL). The reduced life expectancy is frequently due to mast cell infiltration resulting in multi organ failure. Additionally, there are patients who do not benefit from the treatment with Midostaurin (overall response 60%) or suffer from side effects, which lead to reduction or termination of therapy. Currently, the only available curative approach is conditioning poly-chemotherapy followed by allogenic stem cell transplantation (allo-HSCT). However, allo-HSCT is associated with substantial side-effects and, also due to high rates of relapse, only leads to an overall survival of 43% for ASM and 17% for MCL after three years. Thus, better therapeutic options are needed. Recently, we demonstrated that CD117 (KIT-receptor) positive human AML can be efficiently eradicated by anti-CD117 CAR T-cells in vitro and in vivo (Myburgh et al., Leukemia 2020). As mast cells, and also transformed mast cells, highly express CD117, we here tested if anti-CD117 CAR T-cells would equally efficiently eliminate this malignant cell population. We thus co-cultured various established mast cell lines (partly harboring the oncogenic driver mutation KIT D816V) with anti-CD117-CAR T-cells in a 1:1 effector to target ratio in vitro. After 24 hours of co-culturing, the tumor cells were effectively killed, and this was still observed despite increasing the effector to target ratio to 1:4. Also, within 28 days of co-culture, the longest time followed in vitro, tumor cells were controlled and did not outgrow. Increased proliferation of anti-CD117-CAR T-cells in the presence of mast cells was observed and tracked throughout the 28-day experiment. In conclusion, we demonstrate that the human mast cell lines HMC-1.1 KIT V560G, HMC-1.2 KIT V560G, KIT D816V, ROSA KIT WT, ROSA KIT D816V, LAD2 and MCPV-1 can be efficiently targeted and killed in vitro by allogeneic anti-CD117-CAR T-cells. Given that CD117 is expressed on healthy hematopoietic stem and progenitor cells (HSPCs) on a substantially lower level, there might be a therapeutic window for anti-CD117 immunotherapy in advanced forms of mastocytosis. However, as CAR T-cells are highly efficient, collateral damage on healthy HSPCs will likely need to be compensated by subsequent HSC transplantation. We are currently translating these promising in vitro immunotherapeutic settings into surrogate xenogeneic in vivo models. Disclosures Myburgh: University of Zurich: Patents & Royalties: CD117xCD3 TEA. Manz: CDR-Life Inc: Consultancy, Current holder of stock options in a privately-held company; University of Zurich: Patents & Royalties: CD117xCD3 TEA.

“Public communication science in times of the Covid-19 crisis”: DACH 21 preconference

What is public science? What can communication science scholars contribute to society, especially in times of crisis? What are the challenges and limitations of such engagement? These questions were addressed at a recent preconference held on April 7, 2021, titled “Public communication science in times of the Covid-19 crisis”. The preconference was organized as part of the DACH 21 conference (the first three-country conference on commu nication science) and was held online with more than 50 participants. It was an excellent opportunity to stimulate discussion among Swiss, Austrian, and German scholars regarding the self-understanding and societal role of the discipline. The preconference was hosted by the association Öffentliche Medien- und Kommunikations wissenschaft (Public Media and Communication Science, PMCS), which aims to establish, promote, and further develop the concept of public science in the field.The co-presidents of the PMCS association, Prof. Dr. Marlis Prinzing (Hochschule Macro media Köln) and Prof. Dr. Mark Eisenegger (University of Zurich), welcomed all participants to the preconference. They emphasized that the preconference aimed to bring together diverse perspectives and to reflect on principles as laid out in the charter of the association (https://oeffentliche-kowi.org/charta/). This charter consists of fifteen principles and was signed by more than 250 scholars.

Criterion validity of the ActiGraph and activPAL in classifying posture and motion in office-based workers: A cross-sectional laboratory study

Background The ActiGraph and activPAL monitors are the most frequently used thigh-worn devices to measure motion and posture, but the criterion validity to measure sitting, standing and postural transfer in the office setting is not known. Research question: To examine the criterion validity of the ActiGraph and activPAL activity monitors in repeatedly measuring a variety of different postures and motion in the office setting. Methods Twenty office workers from the University of Zurich wore an ActiGraph and activPAL during two identical laboratory experiments lasting approximately 60 minutes each, within a maximum of 7 days. The experimental setting consisted of a standard computer office workstation with an electrically powered height-adjustable desk, a swivel chair without arm rests, a standard chair, a footrest, and a bookcase. The protocol consisted of 24 pre-defined tasks mimicking sitting, standing, stepping, and postural transitions around the workplace. All tasks were supervised and observed by the same experimenter. Results In repeated measurements (40 individual experiments), the percentages of correctly classified tasks for the ActiGraph and activPAL were, respectively, 100% vs. 85% for sitting, 87% vs. 100% for standing, and 100% vs. 73% for postural transitions. Both monitors correctly identified all stepping tasks. The activPAL misclassified sitting with legs outstretched, and sitting with both feet placed beneath the chair, as standing ~25–70% and 45% of the time, respectively. The ActiGraph misclassified standing with the right foot on a footrest as sitting in 65% of events. Conclusions The ActiGraph appears to be slightly more sensitive than the activPAL with respect to the measurement of sitting and postural transitions of short duration, whereas the activPAL seems to be slightly more accurate in capturing standing postures. This knowledge will help guide researchers to choose the best suitable monitor for their research setting.