Genetic Screen for Cell Fitness in High or Low Oxygen Highlights Mitochondrial and Lipid Metabolism.

Human cells are able to sense and adapt to variations in oxygen levels. Historically, much research in this field has focused on hypoxia-inducible factor (HIF) signaling and reactive oxygen species (ROS). Here, we perform genome-wide CRISPR growth screens at 21%, 5%, and 1% oxygen to systematically identify gene knockouts with relative fitness defects in high oxygen (213 genes) or low oxygen (109 genes), most without known connection to HIF or ROS. Knockouts of many mitochondrial pathways thought to be essential, including complex I and enzymes in Fe-S biosynthesis, grow relatively well at low oxygen and thus are buffered by hypoxia. In contrast, in certain cell types, knockout of lipid biosynthetic and peroxisomal genes causes fitness defects only in low oxygen. Our resource nominates genetic diseases whose severity may be modulated by oxygen and links hundreds of genes to oxygen homeostasis.

Oxygen toxicity causes cyclic damage by destabilizing specific Fe-S cluster-containing protein complexes.

Oxygen is toxic across all three domains of life. Yet, the underlying molecular mechanisms remain largely unknown. Here, we systematically investigate the major cellular pathways affected by excess molecular oxygen. We find that hyperoxia destabilizes a specific subset of Fe-S cluster (ISC)-containing proteins, resulting in impaired diphthamide synthesis, purine metabolism, nucleotide excision repair, and electron transport chain (ETC) function. Our findings translate to primary human lung cells and a mouse model of pulmonary oxygen toxicity. We demonstrate that the ETC is the most vulnerable to damage, resulting in decreased mitochondrial oxygen consumption. This leads to further tissue hyperoxia and cyclic damage of the additional ISC-containing pathways. In support of this model, primary ETC dysfunction in the Ndufs4 KO mouse model causes lung tissue hyperoxia and dramatically increases sensitivity to hyperoxia-mediated ISC damage. This work has important implications for hyperoxia pathologies, including bronchopulmonary dysplasia, ischemia-reperfusion injury, aging, and mitochondrial disorders.

Hypoxia treatment reverses neurodegenerative disease in a mouse model of Leigh syndrome.

The most common pediatric mitochondrial disease is Leigh syndrome, an episodic, subacute neurodegeneration that can lead to death within the first few years of life, for which there are no proven general therapies. Mice lacking the complex I subunit, Ndufs4, develop a fatal progressive encephalopathy resembling Leigh syndrome and die at ≈60 d of age. We previously reported that continuously breathing normobaric 11% O2 from an early age prevents neurological disease and dramatically improves survival in these mice. Here, we report three advances. First, we report updated survival curves and organ pathology in Ndufs4 KO mice exposed to hypoxia or hyperoxia. Whereas normoxia-treated KO mice die from neurodegeneration at about 60 d, hypoxia-treated mice eventually die at about 270 d, likely from cardiac disease, and hyperoxia-treated mice die within days from acute pulmonary edema. Second, we report that more conservative hypoxia regimens, such as continuous normobaric 17% O2 or intermittent hypoxia, are ineffective in preventing neuropathology. Finally, we show that breathing normobaric 11% O2 in mice with late-stage encephalopathy reverses their established neurological disease, evidenced by improved behavior, circulating disease biomarkers, and survival rates. Importantly, the pathognomonic MRI brain lesions and neurohistopathologic findings are reversed after 4 wk of hypoxia. Upon return to normoxia, Ndufs4 KO mice die within days. Future work is required to determine if hypoxia can be used to prevent and reverse neurodegeneration in other animal models, and to determine if it can be provided in a safe and practical manner to allow in-hospital human therapeutic trials.

Stability and structure of Penicillium chrysogenum lipase in the presence of organic solvents.

The present work describes the enzymatic properties of Penicillium chrysogenum lipase and its behavior in the presence of organic solvents. The temperature and pH optima of the purified lipase was found to be 55 °C and pH 8.0 respectively. The lipase displayed remarkable stability in both polar and non-polar solvents upto 50% (v/v) concentrations for 72 h. A structural perspective of the purified lipase in different organic solvents was gained by using circular dichroism and intrinsic fluorescence spectroscopy. The native lipase consisted of a predominant α-helix structure which was maintained in both polar and non-polar solvents with the exception of ethyl butyrate where the activity was decreased and the structure was disrupted. The quenching of fluorescence intensity in the presence of organic solvents indicated the transformation of the lipase microenviroment P. chrysogenum lipase offers an interesting system for understanding the solvent stability mechanisms which could be used for rationale designing of engineered lipase biocatalysts for application in organic synthesis in non-aqueous media.

Spatial ordering of chromosomes enhances the fidelity of chromosome partitioning in cyanobacteria.

Many cyanobacteria have been shown to harbor multiple chromosome copies per cell, yet little is known about the organization, replication, and segregation of these chromosomes. Here, we visualize individual chromosomes in the cyanobacterium Synechococcus elongatus via time-lapse fluorescence microscopy. We find that chromosomes are equally spaced along the long axis of the cell and are interspersed with another regularly spaced subcellular compartment, the carboxysome. This remarkable organization of the cytoplasm along with accurate midcell septum placement allows for near-optimal segregation of chromosomes to daughter cells. Disruption of either chromosome ordering or midcell septum placement significantly increases the chromosome partitioning error. We find that chromosome replication is both asynchronous and independent of the position of the chromosome in the cell and that spatial organization is preserved after replication. Our findings on chromosome organization, replication, and segregation in S. elongatus provide a basis for understanding chromosome dynamics in bacteria with multiple chromosomes.

Simultaneous Single Tooth Intrusion and Diastema Closure: A Simplified Approach.

Re-treatment of relapse with a full bonded appliance following an extensive course of fixed mechanotherapy is psychologically unacceptable and time-consuming for the patient. This article presents a simple removable appliance, which intrudes an extruded maxillary incisor with simultaneous closure of a diastema in an effective and fast way, reducing the need for re-treatment with fixed mechanotherapy.

[NH3(CH2)4NH3]SnX4 (X = Br, I): Dion-Jacobson type 2-D perovskites with short interlayer spacing.

Two-dimensional tin(II) halide perovskites stand as an environmentally benign alternative to Pb(II) halide perovskites. However, they are often challenging to make due to the oxidation of Sn(II) ion to more stable Sn(IV) ion. Here we report hybrid tin bromide and iodide perovskites: (1,4-BDA)Sn(IV)Br6 and (1,4-BDA)Sn(II)X4 (where X = Br, I; 1,4-BDA = 1,4-diammoniumbutane) with 0D and 2D structures, respectively. Their synthesis, structural characterization and photophysical properties are reported. They show bandgaps in the 1.94-2.70 eV range.

Organ-specific fuel rewiring in acute and chronic hypoxia redistributes glucose and fatty acid metabolism.

Oxygen deprivation can be detrimental. However, chronic hypoxia is also associated with decreased incidence of metabolic syndrome and cardiovascular disease in high-altitude populations. Previously, hypoxic fuel rewiring has primarily been studied in immortalized cells. Here, we describe how systemic hypoxia rewires fuel metabolism to optimize whole-body adaptation. Acclimatization to hypoxia coincided with dramatically lower blood glucose and adiposity. Using in vivo fuel uptake and flux measurements, we found that organs partitioned fuels differently during hypoxia adaption. Acutely, most organs increased glucose uptake and suppressed aerobic glucose oxidation, consistent with previous in vitro investigations. In contrast, brown adipose tissue and skeletal muscle became "glucose savers," suppressing glucose uptake by 3-5-fold. Interestingly, chronic hypoxia produced distinct patterns: the heart relied increasingly on glucose oxidation, and unexpectedly, the brain, kidney, and liver increased fatty acid uptake and oxidation. Hypoxia-induced metabolic plasticity carries therapeutic implications for chronic metabolic diseases and acute hypoxic injuries.

In vivo protein turnover rates in varying oxygen tensions nominate MYBBP1A as a mediator of the hyperoxia response.

Oxygen deprivation and excess are both toxic. Thus, the body's ability to adapt to varying oxygen tensions is critical for survival. While the hypoxia transcriptional response has been well studied, the post-translational effects of oxygen have been underexplored. In this study, we systematically investigate protein turnover rates in mouse heart, lung, and brain under different inhaled oxygen tensions. We find that the lung proteome is the most responsive to varying oxygen tensions. In particular, several extracellular matrix (ECM) proteins are stabilized in the lung under both hypoxia and hyperoxia. Furthermore, we show that complex 1 of the electron transport chain is destabilized in hyperoxia, in accordance with the exacerbation of associated disease models by hyperoxia and rescue by hypoxia. Moreover, we nominate MYBBP1A as a hyperoxia transcriptional regulator, particularly in the context of rRNA homeostasis. Overall, our study highlights the importance of varying oxygen tensions on protein turnover rates and identifies tissue-specific mediators of oxygen-dependent responses.

The Goldilocks Oxygen Principle: not too little and not too much.

Nature has evolved creative ways to maintain oxygen homeostasis, but what happens when these adaptations are insufficient? Here we discuss biochemical failure points across the oxygen spectrum from 'too little' to 'too much' oxygen and their potential contributions to cardiovascular disease.

Targeting Notch Pathway in Cancer Diagnostics and Therapeutics: An Emerging Approach.

The Notch signaling pathway is an evolutionarily conserved pathway usually present in multicellular organisms, which plays a pivotal role in cell fate determination and proliferation. Due to this property, it is known to be highly oncogenic, especially in the dysregulated version of the Notch pathway, where apoptosis is inhibited and abnormal cell growth is supported. Notch receptors and ligand proteins play an essential role in cancers, such as myeloid leukemia, T-cell lymphoblastic leukemia, and organ-specific, i.e., breast, colon, pancreas, and skin cancers. Any type of cancer generates due to genetic defects, including epigenetic alterations and mutations. The researchers can use these alterations to find a promising diagnostic as well as therapeutic tool for cancer. The successful inhibition of the Notch pathway with the help of specific biomarkers or suppression of gene expression represents a new remedy in cancer research. This article focuses on the various remedies hidden within the Notch pathway's mechanism, primarily based on different patents published in recent years for assisting cancer diagnosis and succeeding treatment.

Post-acute Sequelae in COVID-19 Survivors: an Overview.

In the acute phase of SARS-CoV-2 infection, varying degrees of clinical manifestations have been noticed in patients. Some patients who recovered from the infection developed long-term effects which have become of interest to the scientific and medical communities, as it relates to pathogenesis and the multidisciplinary approach to treatment. Long COVID (long-term or long-haul) is the collective term used to define recovered individuals of SARS-CoV-2 infection who have presented with persistent COVID symptoms, as well as the emergence of disorders and complications. Following the review of literature from major scientific databases, this paper investigated long COVID and the resulting post-sequela effects on survivors, regardless of initial disease severity. The clinical manifestations and multisystem complications of the disease specifically, cardiovascular, neurologic and psychologic, hematologic, pulmonary, dermatologic, and other ailments were discussed. Patients with chronic COVID-19 were found to experience heart thrombosis leading to myocardial infarction, inflammation, lung fibrosis, stroke, venous thromboembolism, arterial thromboembolism, "brain fog", general mood dysfunctions, dermatological issues, and fatigue. As the disease continues to progress and spread, and with the emergence of new variants the management of these persisting symptoms will pose a challenge for healthcare providers and medical systems in the next period of the pandemic. However, more information is needed about long COVID, particularly concerning certain patient populations, variability in follow-up times, the prevalence of comorbidities, and the evolution of the spread of infection. Thus, continued research needs to be conducted concerning the disease pathology to develop preventative measures and management strategies to treat long COVID.

Current advancements and future prospects of COVID-19 vaccines and therapeutics: a narrative review.

Coronavirus disease 2019 (COVID-19) has made a global impact on the daily lives of humanity, devastating health systems, and cataclysmically affecting the world's economy. Currently, the Standard Public Health Protective practices consist of but are not limited to wearing masks, social distancing, isolating sick and exposed people, and contact tracing. Scientists around the globe undertook swift scientific efforts to develop safe and effective therapeutics and vaccines to combat COVID-19. Presently, as of mid-March 2022, 57.05% of the world population have been fully vaccinated, and 65.3% of the United States of America's (USA) total population have been fully vaccinated while 76.7% have received at least one dose of the vaccine. This article explores the various vaccines created through modern science and technology, including their safety, efficacy, and mechanism of action. Although the vaccines produced are up to 95.0% efficacious, their efficacy wanes over time, underscoring the need for booster doses. Also, vaccination has not been able to prevent "breakthrough" infections. The limitations of the SARS-CoV-2 vaccines indicate that further measures are required to ensure a firm control of the COVID-19 pandemic. Therefore, the Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for the use of certain therapeutic agents because they have shown remarkable clinical outcomes. Several therapeutic agents for the treatment of mild-to-moderate COVID-19 include Gilead's remdesivir, Regeneron's casirivimab and imdevimab combination, Eli Lilly's baricitinib and remdesivir combination, Pfizer's co-packaged nirmatrelvir tablets and ritonavir tablets, and Merck's molnupiravir capsules. Hence concerted efforts in early and accurate diagnosis, education on the COVID-19 virulence, transmission and preventive measures, global vaccination, and therapeutic agents could bring this COVID-19 pandemic under control across the globe.

Reactogenicity to COVID-19 vaccination in the United States of America.

PURPOSE: In the United States, Pfizer-BioNTech, Moderna, and Janssen's coronavirus disease 2019 (COVID-19) vaccines have been granted Emergency Use Authorization (EUA) with the Pfizer-BioNTech vaccine presently approved by the US Food and Drug Administration. The purpose of this study is to analyze passive surveillance data on COVID-19 vaccine adverse reaction in the United States. MATERIALS AND METHODS: We analyzed passive surveillance data on COVID-19 vaccine adverse reactions which were retrieved from the Vaccine Adverse Event Reporting System database. Retrieved records on demographic information as well as the top 10 common vaccine adverse events were extracted and assessed from 200 of the most recently reported cases for the study analysis. RESULTS: Local and systemic adverse reactions were reported in the study. A significant difference (p<0.05) was recorded for the top 10 systemic reactions by age category (0.041) and by gender (0.002). Analysis of the top five systemic reactions, stratified by vaccine type yielded a significant difference (p<0.05) for chills (p=0.044), and when stratified by age group and type of vaccination received, it yielded a significant difference (p<0.05) for fatigue (p=0.023). Overall, Pfizer had 182 persons (91.0%) reporting adverse events, Moderna with 13 (6.5%), and Janssen with 5 (2.5%). CONCLUSION: Mild side effects were reported following vaccination with the EUA COVID-19 vaccines in the United States. Thus, continuous monitoring and reporting of all adverse events are recommended to ensure the safety of vaccination.

A Robotic Device to Enhance Nursing Home Provider Telepresence During and After the COVID-19 Pandemic.

The COVID-19 pandemic presented significant challenges to face-to-face communication with people residing in post-acute and long-term care (PALTC) settings. Telemedicine is an alternative, but facility staff may be overburdened with the management of the equipment. Here we introduce the use of a mobile HIPPA-compliant telepresence robot (MTR) to bridge this barrier, which may be beneficial to reimagine options for PALTC in the future.

Coordinated Transcriptional and Catabolic Programs Support Iron-Dependent Adaptation to RAS-MAPK Pathway Inhibition in Pancreatic Cancer.

The mechanisms underlying metabolic adaptation of pancreatic ductal adenocarcinoma (PDA) cells to pharmacologic inhibition of RAS-MAPK signaling are largely unknown. Using transcriptome and chromatin immunoprecipitation profiling of PDA cells treated with the MEK inhibitor (MEKi) trametinib, we identify transcriptional antagonism between c-MYC and the master transcription factors for lysosome gene expression, the MiT/TFE proteins. Under baseline conditions, c-MYC and MiT/TFE factors compete for binding to lysosome gene promoters to fine-tune gene expression. Treatment of PDA cells or patient organoids with MEKi leads to c-MYC downregulation and increased MiT/TFE-dependent lysosome biogenesis. Quantitative proteomics of immunopurified lysosomes uncovered reliance on ferritinophagy, the selective degradation of the iron storage complex ferritin, in MEKi-treated cells. Ferritinophagy promotes mitochondrial iron-sulfur cluster protein synthesis and enhanced mitochondrial respiration. Accordingly, suppressing iron utilization sensitizes PDA cells to MEKi, highlighting a critical and targetable reliance on lysosome-dependent iron supply during adaptation to KRAS-MAPK inhibition. SIGNIFICANCE: Reduced c-MYC levels following MAPK pathway suppression facilitate the upregulation of autophagy and lysosome biogenesis. Increased autophagy-lysosome activity is required for increased ferritinophagy-mediated iron supply, which supports mitochondrial respiration under therapy stress. Disruption of ferritinophagy synergizes with KRAS-MAPK inhibition and blocks PDA growth, thus highlighting a key targetable metabolic dependency. See related commentary by Jain and Amaravadi, p. 2023. See related article by Santana-Codina et al., p. 2180. This article is highlighted in the In This Issue feature, p. 2007.

Airway stem cells sense hypoxia and differentiate into protective solitary neuroendocrine cells.

Neuroendocrine (NE) cells are epithelial cells that possess many of the characteristics of neurons, including the presence of secretory vesicles and the ability to sense environmental stimuli. The normal physiologic functions of solitary airway NE cells remain a mystery. We show that mouse and human airway basal stem cells sense hypoxia. Hypoxia triggers the direct differentiation of these stem cells into solitary NE cells. Ablation of these solitary NE cells during hypoxia results in increased epithelial injury, whereas the administration of the NE cell peptide CGRP rescues this excess damage. Thus, we identify stem cells that directly sense hypoxia and respond by differentiating into solitary NE cells that secrete a protective peptide that mitigates hypoxic injury.

System Redesign: The Value of a Primary Care Liaison Model to Address Unmet Social Needs among Older Primary Care Patients.

Assessing and addressing social determinants of health can improve health outcomes of older adults. The Nebraska Geriatrics Workforce Enhancement Program implemented a primary care liaison (PCL) model of care, including training primary care staff to assess and address unmet social needs, patient counseling to identify unmet needs, and mapping referral services through cross-sectoral partnerships. A PCL worked with three patient-centered medical homes (PCMHs) that are part of a large integrative health system. A mixed-methods approach using a post-training survey and a patient tracking tool, was used to understand the reach, adoption, and implementation of the PCL model. From June 2020 to May 2021, the PCL trained 61 primary care staff to assess and address unmet social needs of older patients. A total of 327 patients, aged 65 years and older and within 3-5 days of acute-care hospital discharges, were counseled by the PCL. For patients with unmet needs, support services were arranged through community agencies: transportation (37%), in-home care (33%), food (16%), caregiver support (2%), legal (16%), and other (16%). Our preliminary results suggest that the PCL model is feasible and implementable within PCMH settings to address unmet social needs of older patients to improve their health outcomes.

Turning the Oxygen Dial: Balancing the Highs and Lows.

Oxygen is both vital and toxic to life. Molecular oxygen is the most used substrate in the human body and is required for several hundred diverse biochemical reactions. The discovery of the PHD-HIF-pVHL system revolutionized our fundamental understanding of oxygen sensing and cellular adaptations to hypoxia. It deepened our knowledge of the biochemical underpinnings of numerous diseases, ranging from anemia to cancer. Cellular dysfunction and tissue pathology can result from a mismatch of oxygen supply and demand. Recent work has shown that mitochondrial disease models display tissue hyperoxia and that disease pathology can be reversed by normalization of excess oxygen, suggesting that certain disease states can potentially be treated by modulating oxygen levels. In this review, we describe cellular and organismal mechanisms of oxygen sensing and adaptation. We provide a revitalized framework for understanding pathologies of too little or too much oxygen.