Effects of alveolar surfactant aggregates on T-lymphocyte proliferation

AbstractThe effects of alveolar large aggregate (LA) and small aggregate (SA) surfactant subfractions isolated from healthy adult rats on mitogen-stimulated proliferative responses of human peripheral blood mononuclear cells (PBMC) was examined. Various concentrations of total surfactant suppressed proliferation of stimulated lymphocytes by up to 95% of mitogen-stimulated cells alone. LA subfractions of total surfactant had no effect on proliferation, whereas SA significantly enhanced the lymphocyte proliferation at lower concentrations (7.8 μg/ml) compared to mitogen-stimulated cells alone. Higher concentrations of SA (62.5 μg/ml) inhibited lymphocyte proliferation. This concentration-dependent effect of SA on proliferation of PBMC was also present when cells were stimulated with various lectins including anti-CD3, concanavalin A and phytohemagglutinin. Analysis of the supernatant of mitogen-stimulated cell cultures treated with inhibitory concentrations of SA showed decreased amounts of interleukin (IL)-2, compared to cells alone, which could be reversed by adding exogenous IL-2 to the cell cultures with the SA. These results suggest that alveolar surfactant subfractions have distinct functions within the alveoli, both biophysically and with respect to their effects on the host’s immunomodulatory responses

Real-time Measurement of Cytosolic Free Calcium Concentration in Jurkat Cells during ELF Magnetic Field Exposure and Evaluation of the Role of Cell Cycle

Extremely low frequency magnetic fields (ELF MF) have been reported to alter a number of cell signaling pathways, including those involved in proliferation, differentiation and apoptosis where cytosolic free calcium ([Ca(2+)](c)) plays an important role. To better understand the biological conditions under which ELF MF exposure might alter [Ca(2+)](c), we measured [Ca(2+)](c) by ratiometric fluorescence spectrophotometry during exposure to ELF MF in Jurkat E6.1 cells synchronized to different phases of the cell cycle. Suspensions of cells were exposed either to a near zero MF (Null) or a 60 Hz, 100 microT sinusoidal MF superimposed upon a collinear 78.1 microT static MF (AC + DC). An initial series of experiments indicated that the maximum increase in [Ca(2+)](c) above baseline after stimulation with anti-CD3 was significantly higher in samples exposed to AC + DC (n = 30) compared to Null (n = 30) with the largest difference in G2-M enriched samples. However, in a second study with G2-M enriched cells, samples treated with AC + DC (n = 17) were not statistically different from Null-treated samples (n = 27). Detailed analysis revealed that the dynamics in [Ca(2+)](c) before and after stimulation with anti-CD3 were dissimilar between Null samples from each study. From the results, we concluded (i) that the ELF MF increased [Ca(2+)](c) during an antibody-induced signaling event, (ii) that the ELF MF effect did not depend to a large degree on cell cycle, and (iii) that a field-related change in [Ca(2+)](c) signaling appeared to correlate with features in the [Ca(2+)](c) dynamics. Future work could evaluate [Ca(2+)](c) dynamics in relation to the phase of the cell cycle and inter-study variation, which may reveal factors important for the observation of real-time effects of ELF MF on [Ca(2+)](c)

Functional Analysis of a Type 1 Parathyroid Hormone Receptor Intracellular Tail Mutant [KRK(484-6)AAA]: Effects on Second Messenger Generation and Cellular Targeting

The parathyroid hormone receptor type 1 (PTHR1) is activated by parathyroid hormone (PTH) and PTH-related protein (PTHrP) and primarily signals via intracellular pathways involving adenylyl cyclase and phospholipase C. The intracellular tail domain of the PTHR1 contributes to G protein subunit coupling that is important for second messenger signalling. In addition, the intracellular domain has a potential nuclear localization sequence (NLS) that, if functional, could point to an intracrine role for the receptor. In the present study, we have utilized 2 sets of constructs that employ either a [KRK(484-486)AAA](3Ala) mutation in the putative NLS or the non-mutant counterpart and included (a) the full-length rat PTHR1 with FLAG and c-myc epitope tags at the N-terminus and C-terminus, respectively (designated as PTHR1(3Ala)-TAG and PTHR1-TAG); and (b) only the putative NLS-containing intracellular domain (471-488), with green fluorescent protein (GFP) fused to the C-terminus (designated as GFP-(3Ala)471-488 or GFP-471-488). Porcine kidney LLC-PK1 cells stably expressing the PTHR1(3Ala)-TAG exhibited reduced signalling via both cAMP and cytosolic calcium transients in spite of greater cell surface expression relative to cells expressing PTHR1-TAG. We also examined the ability of the intracellular tail to influence the cellular localization of a heterologous protein. LLC-PK1 cells transiently transfected with GFP-471-488, exhibited increased fluorescence within the nucleus, relative to cells transfected with GFP alone that was not observed when cells were transiently transfected with the mutated construct, GFP-(3Ala)471-488. However, LLC-PK1 cells transiently transfected with either the full-length PTHR1-TAG or the PTHR1(3Ala)-TAG constructs did not exhibit nuclear localization of these receptors. Moreover, mouse osteoblast-like cells (MC3T3-E1) transiently expressing PTHR1-TAG also failed to demonstrate nuclear localization, although both full-length PTHR1 constructs exhibited plasma membrane immunofluorescence in both cell lines. Thus, the 484-486 sequence is critical for the full signalling responsiveness of the intact PTHR1, but the putative nuclear localization signal may not function as such within the intact receptor

Systems psychodynamics: The formative years of an interdisciplinary field at the Tavistock Institute. History of psychology

Systems psychodynamics is an interdisciplinary field amalgamating a triad of influences-the practice of psychoanalysis, the theories and methods of the field of group relations, and the task and boundary awareness of open systems perspectives. Although systems psychodynamics is not a new field of study, there has been a general lack of awareness of its roots, how its formative elements have become intertwined over the years, and the role of the Tavistock Institute in developments in the field. This article provides a synthesis of this history and focuses, in particular, on the intellectual foundations of the Tavistock method of working experientially with groups and the application of this method to the study of organizations. Systems psychodynamics is an interdisciplinary field that integrates three disciplines-the practice of psychoanalysis, the theories and methods of group relations, and open systems perspectives. Systems psychodynamics is "a term used to refer to the collective psychological behavior" (Neumann, 1999, p. 57) within and between groups and organizations. "Systems psychodynamics, therefore, provides a way of thinking about energizing or motivating forces resulting from the interconnection between various groups and sub-units of a social system" (Neumann, 1999, p. 57). Although systems psychodynamics is not a new field of study, there has been a general lack of awareness of its roots, how its formative elements have become intertwined over the years, and the role of the Tavistock Institute of Human Relations (Tavistock Institute) in developments in the field. This article provides a synthesis of this history and focuses, in particular, on the intellectual foundations of the Tavistock method of working experientially with groups and the application of this method to the study of organizations. It will discuss the formative years of systems psychodynamics from the late 1800s, with developments in psychoanalysis and theories about groups, until I thank the following people for their assistance in the creation of this article

Respiratory support in patients with severe COVID-19 in the International Severe Acute Respiratory and Emerging Infection (ISARIC) COVID-19 study: a prospective, multinational, observational study

Background: Up to 30% of hospitalised patients with COVID-19 require advanced respiratory support, including high-flow nasal cannulas (HFNC), non-invasive mechanical ventilation (NIV), or invasive mechanical ventilation (IMV). We aimed to describe the clinical characteristics, outcomes and risk factors for failing non-invasive respiratory support in patients treated with severe COVID-19 during the first two years of the pandemic in high-income countries (HICs) and low middle-income countries (LMICs). Methods: This is a multinational, multicentre, prospective cohort study embedded in the ISARIC-WHO COVID-19 Clinical Characterisation Protocol. Patients with laboratory-confirmed SARS-CoV-2 infection who required hospital admission were recruited prospectively. Patients treated with HFNC, NIV, or IMV within the first 24 h of hospital admission were included in this study. Descriptive statistics, random forest, and logistic regression analyses were used to describe clinical characteristics and compare clinical outcomes among patients treated with the different types of advanced respiratory support. Results: A total of 66,565 patients were included in this study. Overall, 82.6% of patients were treated in HIC, and 40.6% were admitted to the hospital during the first pandemic wave. During the first 24 h after hospital admission, patients in HICs were more frequently treated with HFNC (48.0%), followed by NIV (38.6%) and IMV (13.4%). In contrast, patients admitted in lower- and middle-income countries (LMICs) were less frequently treated with HFNC (16.1%) and the majority received IMV (59.1%). The failure rate of non-invasive respiratory support (i.e. HFNC or NIV) was 15.5%, of which 71.2% were from HIC and 28.8% from LMIC. The variables most strongly associated with non-invasive ventilation failure, defined as progression to IMV, were high leukocyte counts at hospital admission (OR [95%CI]; 5.86 [4.83–7.10]), treatment in an LMIC (OR [95%CI]; 2.04 [1.97–2.11]), and tachypnoea at hospital admission (OR [95%CI]; 1.16 [1.14–1.18]). Patients who failed HFNC/NIV had a higher 28-day fatality ratio (OR [95%CI]; 1.27 [1.25–1.30]). Conclusions: In the present international cohort, the most frequently used advanced respiratory support was the HFNC. However, IMV was used more often in LMIC. Higher leucocyte count, tachypnoea, and treatment in LMIC were risk factors for HFNC/NIV failure. HFNC/NIV failure was related to worse clinical outcomes, such as 28-day mortality. Trial registration This is a prospective observational study; therefore, no health care interventions were applied to participants, and trial registration is not applicable

Association of Country Income Level With the Characteristics and Outcomes of Critically Ill Patients Hospitalized With Acute Kidney Injury and COVID-19

Introduction: Acute kidney injury (AKI) has been identified as one of the most common and significant problems in hospitalized patients with COVID-19. However, studies examining the relationship between COVID-19 and AKI in low- and low-middle income countries (LLMIC) are lacking. Given that AKI is known to carry a higher mortality rate in these countries, it is important to understand differences in this population. Methods: This prospective, observational study examines the AKI incidence and characteristics of 32,210 patients with COVID-19 from 49 countries across all income levels who were admitted to an intensive care unit during their hospital stay. Results: Among patients with COVID-19 admitted to the intensive care unit, AKI incidence was highest in patients in LLMIC, followed by patients in upper-middle income countries (UMIC) and high-income countries (HIC) (53%, 38%, and 30%, respectively), whereas dialysis rates were lowest among patients with AKI from LLMIC and highest among those from HIC (27% vs. 45%). Patients with AKI in LLMIC had the largest proportion of community-acquired AKI (CA-AKI) and highest rate of in-hospital death (79% vs. 54% in HIC and 66% in UMIC). The association between AKI, being from LLMIC and in-hospital death persisted even after adjusting for disease severity. Conclusions: AKI is a particularly devastating complication of COVID-19 among patients from poorer nations where the gaps in accessibility and quality of healthcare delivery have a major impact on patient outcomes

The value of open-source clinical science in pandemic response: lessons from ISARIC

International audienc