The Chlamydomonas reinhardtii proteins Ccp1 and Ccp2 are required for long-term growth, but are not necessary for efficient photosynthesis, in a low-CO\u3csub\u3e2\u3c/sub\u3e environment

The unicellular green alga Chlamydomonas reinhardtii acclimates to a low-CO2 environment by modifying the expression of a number of messages. Many of the genes that increase in abundance during acclimation to low-CO2 are under the control of the putative transcription factor Cia5. C. reinhardtii mutants null for cia5 do not express several of the known low-CO2 inducible genes and do not grow in a low-CO2 environment. Two of the genes under the control of Cia5, Ccp1 and Ccp2, encode polypeptides that are localized to the chloroplast envelope and have a high degree of similarity to members of the mitochondrial carrier family of proteins. Since their discovery, Ccp1/2 have been candidates for bicarbonate uptake proteins of the chloroplast envelope membrane. In this report, RNA interference was successful in dramatically decreasing the abundance of the mRNAs for Ccp1 and Ccp2. The abundance of the Ccp1 and Ccp2 proteins were also reduced in the RNAi strains. The RNAi strains grew slower than WT in a low-CO2 environment, but did not exhibit a mutant carbon concentrating phenotype as determined by the cells\u27 apparent affinity for dissolved inorganic carbon. Possible explanations of this RNAi phenotype are discussed

Single-Cell Analysis of Aneurysmal Aortic Tissue in Patients with Marfan Syndrome Reveals Dysfunctional TGF-β Signaling

The molecular and cellular processes leading to aortic aneurysm development in Marfan syndrome (MFS) remain poorly understood. In this study, we examined the changes of aortic cell populations and gene expression in MFS by performing single-cell RNA sequencing (scRNA seq) on ascending aortic aneurysm tissues from patients with MFS (n = 3) and age-matched non-aneurysmal control tissues from cardiac donors and recipients (n = 4). The expression of key molecules was confirmed by immunostaining. We detected diverse populations of smooth muscle cells (SMCs), fibroblasts, and endothelial cells (ECs) in the aortic wall. Aortic tissues from MFS showed alterations of cell populations with increased de-differentiated proliferative SMCs compared to controls. Furthermore, there was a downregulation of MYOCD and MYH11 in SMCs, and an upregulation of COL1A1/2 in fibroblasts in MFS samples compared to controls. We also examined TGF-β signaling, an important pathway in aortic homeostasis. We found that TGFB1 was significantly upregulated in two fibroblast clusters in MFS tissues. However, TGF-β receptor genes (predominantly TGFBR2) and SMAD genes were downregulated in SMCs, fibroblasts, and ECs in MFS, indicating impairment in TGF-β signaling. In conclusion, despite upregulation of TGFB1, the rest of the canonical TGF-β pathway and mature SMCs were consistently downregulated in MFS, indicating a potential compromise of TGF-β signaling and lack of stimulus for SMC differentiation

Guidelines for investigating causality of sequence variants in human disease

The discovery of rare genetic variants is accelerating, and clear guidelines for distinguishing disease-causing sequence variants from the many potentially functional variants present in any human genome are urgently needed. Without rigorous standards we risk an acceleration of false-positive reports of causality, which would impede the translation of genomic research findings into the clinical diagnostic setting and hinder biological understanding of disease. Here we discuss the key challenges of assessing sequence variants in human disease, integrating both gene-level and variant-level support for causality. We propose guidelines for summarizing confidence in variant pathogenicity and highlight several areas that require further resource development

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Illness Intrusiveness in Veterans with Congestive Heart Failure

Illness intrusiveness refers to the lifestyle disruptions sustained by the symptoms and treatment effects of chronic illness. These disruptions can consist of changes in an individual\u27s continued involvement in activities and interests that they once enjoyed, thus compromising quality of life (Devins, 2006). As heart disease continues to be a leading cause of death and a commonly diagnosed disease in the U.S. population, investigating illness intrusiveness in an older adult, CHF population can provide valuable information that could influence interventions designed to address illness intrusiveness in patients\u27 lives. This study used archival data from a previous study of 103 CHF patients treated at a VA hospital who are 60+ years of age. The purpose of this study was to test the three-factor structure of the Illness Intrusiveness Rating Scale (IIRS; Devins et al., 1983) in CHF patients and describe the Life Domain(s) (IIRS subscales) most impacted by CHF. Confirmatory factor analysis determined the three-factor structure of the IIRS to be a good fit for the data of this CHF patient sample, further demonstrating construct validity of the instrument across illness groups. This study also found a significant difference between levels of illness intrusiveness among the three IIRS subscales with the Instrumental Life Domain being the most elevated, as predicted. In addition, this study investigated whether the sociodemographic factors of income, education, and living status are related to levels of perceived illness intrusiveness using one-way between groups analysis of variance (ANOVA). The hypotheses predicting relationships between these sociodemographic variables and illness intrusiveness levels were generally unsupported

Illness Intrusiveness Mediates the Relationship between Heart Failure Severity and Depression in Older Adults

Depression frequently co-occurs in heart failure (HF) patients, causing significant interference and negative health outcomes. This case-controlled study explored the construct of illness intrusiveness and examined its relationship to HF severity and depression. Older veterans (n = 104) with an HF diagnosis completed a one-time assessment that included demographics, depressive symptoms (Geriatric Depression Scale), the Illness Intrusiveness Rating Scale (IIRS), and HF quality of life and functional abilities (Kansas City Cardiomyopathy Questionnaire [KCCQ]). Analyses included exploratory correlations between IIRS and KCCQ items, a confirmatory factor analysis (IIRS), and formal mediational analyses. Results indicated that the IIRS had adequate internal consistency and concurrent validity, with support for its established three-factor model. Regression analyses indicated that illness intrusiveness mediated HF illness severity and depression. In conclusion, illness intrusiveness may be a better indicator of depression than illness severity (HF symptoms); thus research methods and interventions targeted at reducing illness intrusiveness merit further investigation