Mitochondrial pyruvate transport regulates presynaptic metabolism and neurotransmission.

Glucose has long been considered the primary fuel source for the brain. However, glucose levels fluctuate in the brain during sleep, intense circuit activity, or dietary restrictions, posing significant metabolic stress. Here, we demonstrate that the mammalian brain utilizes pyruvate as a fuel source, and pyruvate can support neuronal viability in the absence of glucose. Nerve terminals are sites of metabolic vulnerability within a neuron and we show that mitochondrial pyruvate uptake is a critical step in oxidative ATP production in hippocampal terminals. We find that the mitochondrial pyruvate carrier is post-translationally modified by lysine acetylation which in turn modulates mitochondrial pyruvate uptake. Importantly, our data reveal that the mitochondrial pyruvate carrier regulates distinct steps in synaptic transmission, namely, the spatiotemporal pattern of synaptic vesicle release and the efficiency of vesicle retrieval, functions that have profound implications for synaptic plasticity. In summary, we identify pyruvate as a potent neuronal fuel and mitochondrial pyruvate uptake as a critical node for the metabolic control of synaptic transmission in hippocampal terminals.

Sirtuin3 ensures the metabolic plasticity of neurotransmission during glucose deprivation.

Neurotransmission is an energetically expensive process that underlies cognition. During intense electrical activity or dietary restrictions, the glucose level in the brain plummets, forcing neurons to utilize alternative fuels. However, the molecular mechanisms of neuronal metabolic plasticity remain poorly understood. Here, we demonstrate that glucose-deprived neurons activate the CREB and PGC1α transcriptional program, which induces expression of the mitochondrial deacetylase Sirtuin 3 (Sirt3) both in vitro and in vivo. We show that Sirt3 localizes to axonal mitochondria and stimulates mitochondrial oxidative capacity in hippocampal nerve terminals. Sirt3 plays an essential role in sustaining synaptic transmission in the absence of glucose by providing metabolic support for the retrieval of synaptic vesicles after release. These results demonstrate that the transcriptional induction of Sirt3 facilitates the metabolic plasticity of synaptic transmission.

Decreased plasma cartilage acidic protein 1 in COVID-19.

Cartilage acidic protein-1 (CRTAC1) is produced by several cell types, including Type 2 alveolar epithelial (T2AE) cells that are targeted by SARS-CoV2. Plasma CRTAC1 is known based on proteomic surveys to be low in patients with severe COVID-19. Using an ELISA, we found that patients treated for COVID-19 in an ICU almost uniformly had plasma concentrations of CRTAC1 below those of healthy controls. Magnitude of decrease in CRTAC1 distinguished COVID-19 from other causes of acute respiratory decompensation and correlated with established metrics of COVID-19 severity. CRTAC1 concentrations below those of controls were found in some patients a year after hospitalization with COVID-19, long COVID after less severe COVID-19, or chronic obstructive pulmonary disease. Decreases in CRTAC1 in severe COVID-19 correlated (r = 0.37, p = 0.0001) with decreases in CFP (properdin), which interacts with CRTAC1. Thus, decreases of CRTAC1 associated with severe COVID-19 may result from loss of production by T2AE cells or co-depletion with CFP. Determination of significance of and reasons behind decreased CRTAC1 concentration in a subset of patients with long COVID will require analysis of roles of preexisting lung disease, impact of prior acute COVID-19, age, and other confounding variables in a larger number of patients.

Sirtuin3 ensures the metabolic plasticity of neurotransmission during glucose deprivation.

Neurotransmission is an energetically expensive process that underlies cognition. During intense electrical activity or dietary restrictions, glucose levels in the brain plummet, forcing neurons to utilize alternative fuels. However, the molecular mechanisms of neuronal metabolic plasticity remain poorly understood. Here, we demonstrate that glucose-deprived neurons activate the CREB and PGC1α transcriptional program that induces the expression of the mitochondrial deacetylase Sirtuin 3 (Sirt3) both in vitro and in vivo . We show that Sirt3 localizes to axonal mitochondria and stimulates mitochondrial oxidative capacity in hippocampal nerve terminals. Sirt3 plays an essential role in sustaining synaptic transmission in the absence of glucose by powering the retrieval of synaptic vesicles after release. These results demonstrate that the transcriptional induction of Sirt3 ensures the metabolic plasticity of synaptic transmission. Highlights: Glucose deprivation drives transcriptional reprogramming of neuronal metabolism via CREB and PGC1α. Glucose or food deprivation trigger the neuronal expression of mitochondrial deacetylase sirtuin 3 (Sirt3) both in vitro and in vivo . Sirt3 stimulates oxidative ATP synthesis in nerve terminals.Sirt3 sustains the synaptic vesicle cycle in the absence of glucose.

Influence of right ventricular structure and function on hospital outcomes in COVID-19 patients.

BACKGROUND: The impact of the right ventricular (RV) structure and function on the in-hospital outcomes in patients with COVID-19 infection has not been rigorously investigated. OBJECTIVES: The main aim of our study was to investigate in-hospital outcomes including mortality, ICU admission, mechanical ventilation, pressor support, associated with RV dilatation, and RV systolic dysfunction in COVID-19 patients without a history of pulmonary hypertension. METHODS: It was a single academic tertiary center, retrospective cohort study of 997 PCR-confirmed COVID-19 patients. One hundred ninty-four of those patients did not have a history of pulmonary hypertension and underwent transthoracic echocardiography at the request of the treating physicians for clinical indications. Clinical endpoints which included mortality, ICU admission, need for mechanical ventilation or pressor support were abstracted from the electronic charts. RESULTS: Patients' mean age was 68+/-16 years old and 42% of the study population were females. COPD was reported in 13% of the study population, whereas asthma was 10%, and CAD was 25%. The mean BMI was 29.8+/-9.5 kg/m2. Overall mortality was 27%, 46% in ICU patients, and 9% in the rest of the cohort. There were no significant differences in co-morbidities between expired patients and the survivors. A total of 19% of patients had evidence of RV dilatation and 17% manifested decreased RV systolic function. RV dilatation or decreased RV systolic function were noted in 24% of the total study population. RV dilatation was significantly more common in expired patients (15% vs 29%, p = 0.026) and was associated with increased mortality in patients treated in the ICU (HR 2.966, 95%CI 1.067-8.243, p = 0.037), who did not need require positive pressure ventilation, IV pressor support or acute hemodialysis. CONCLUSIONS: In hospitalized COVID-19 patients without a history of pulmonary hypertension, RV dilatation is associated with a 2-fold increase in inpatient mortality and a 3-fold increase in ICU mortality.

The Relationship of Obesity and OSA to the Development of Sarcoidosis: A Large Retrospective Case-Control US Veterans Administration Analysis.

BACKGROUND: Previous studies have demonstrated an association between BMI and the development of sarcoidosis. We investigated this association and the association between OSA and the development of sarcoidosis in a US Veterans Health Administration database. RESEARCH QUESTIONS: Is the presence of OSA or the BMI associated with the development of sarcoidosis over the subsequent 12 months? STUDY DESIGN AND METHODS: We identified patients with sarcoidosis and OSA through International Classification of Diseases, Ninth and Tenth Revision, codes. We selected a random sample of control participants with no record of sarcoidosis. All patients with sarcoidosis had at least one BMI value recorded in the 12 months before the sarcoidosis diagnosis was made. For the patients without sarcoidosis, the BMI values were obtained over intervals 12 months before a random date. We compared the BMI and the percentage of patients with OSA in the sarcoidosis group and in patients without sarcoidosis. RESULTS: We analyzed 10,512 patients with sarcoidosis and 2,709,884 patients without sarcoidosis. We found no association between BMI and the rate of sarcoidosis developing. Post hoc statistical power calculations verified that these null results were meaningful and not the result of insufficient statistical power. We also found that a diagnosis of OSA was protective of sarcoidosis developing. Using a conditional logistic regression model with strata for age, sex, and BMI in the same 12-month period, a 49.0% lower odds of sarcoidosis was found in patients with OSA compared with patients without a diagnosis of OSA. Although the primary outcomes were assessed at 12 months before the diagnosis of sarcoidosis, these results basically held when examined at 3 and 6 months before the diagnosis was made. INTERPRETATION: These findings suggest that increased BMI is not associated positively with a greater odds of sarcoidosis developing. Furthermore, these results suggest that the presence of OSA lowers the odds of sarcoidosis developing.

Incidence and risk factors for secondary pulmonary infections in patients hospitalized with coronavirus disease 2019 pneumonia.

BACKGROUND: Secondary pulmonary infections (SPI) have not been well described in COVID-19 patients. Our study aims to examine the incidence and risk factors of SPI in hospitalized COVID-19 patients with pneumonia. METHODS: This was a retrospective, single-center study of adult COVID-19 patients with radiographic evidence of pneumonia admitted to a regional tertiary care hospital. SPI was defined as microorganisms identified on the respiratory tract with or without concurrent positive blood culture results for the same microorganism obtained at least 48 h after admission. RESULTS: Thirteen out of 244 (5%) had developed SPI during hospitalization. The median of the nadir lymphocyte count during hospitalization was significantly lower in patients with SPI as compared to those without SPI [0.4 K/uL (IQR 0.3-0.5) versus 0.6 K/uL (IQR 0.3-0.9)]. Patients with lower nadir lymphocyte had an increased risk of developing SPI with odds ratio (OR) of 1.21 (95% CI: 1.00 to 1.47, p = 0.04) per 0.1 K/uL decrement in nadir lymphocyte. The baseline median inflammatory markers of CRP [166.4 mg/L vs. 100.0 mg/L, p = 0.01] and d-dimer (18.5 mg/L vs. 1.4 mg/L, p<0.01), and peak procalcitonin (1.4 ng/mL vs. 0.3 ng/mL, p<0.01) and CRP (273.5 mg/L vs. 153.7 mg/L, p<0.01) during hospitalization were significantly higher in SPI group. CONCLUSIONS: The incidence of SPI in hospitalized COVID-19 patients was 5%. Lower nadir median lymphocyte count during hospitalization was associated with an increased OR of developing SPI. The CRP and d-dimer levels on admission, and peak procalcitonin and CRP levels during hospitalization were higher in patients with SPI.

Topical Ketotifen Fumarate Inhibits Choroidal Mast Cell Degranulation and Loss of Retinal Pigment Epithelial Cells in Rat Model for Geographic Atrophy.

Purpose: This study evaluates whether topical ketotifen fumarate (KTF) can prevent geographic atrophy (GA)-like phenotypes in a rat model. Methods: Pharmacokinetics (PKs) of KTF after topical administration twice daily for 5 days was analyzed in rat retina, retinal pigment epithelium (RPE)/choroid/sclera, and in plasma by an liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Rats were then given hydrogel implants +/- 48/80 in the superior subconjunctival space and topically treated with 1% and 0.25% of KTF or phosphate buffer saline (PBS) twice daily. Rats were euthanized at 1, 2, 4, and 8 weeks postinjection. Choroidal mast cells (MCs) were stained with nonspecific esterase and the RPE monolayer was labeled with RPE65 and ZO-1 in whole mount choroids. Retinal and choroidal areas were determined in cryosections stained with picrosirius red. Dark-adapted electroretinogram (ERG) was also performed to evaluate retinal function. Results: PK results showed the highest level of KTF (average 5.6 nM/mg) in the RPE/choroid/sclera in rats given topical 1% KTF. Topical 1% KTF significantly reduced choroidal MC degranulation at 1 week and 2 weeks (both P < 0.001) and RPE loss at 4 weeks (P < 0.001) as well as retinal and choroidal thinning (both P < 0.001) and reduction in ERG amplitude at 8 weeks (P < 0.05) compared to PBS. Similar results were obtained with 0.25% KTF. Conclusions: Both 1% and 0.25% KTF eye drops effectively reduced MC degranulation, RPE loss, and retinal and choroidal thinning while preventing the decline of ERG amplitude in a GA-like rat model. These data suggest that topical KTF might be a new therapeutic drug for treating GA. Translational Relevance: The results of this study demonstrate that topical KTF successfully reduced GA-like phenotypes in a rat model and may provide a novel therapy for GA.

A Young Woman With Recurrent Episodes of Fever and Cough.

CASE PRESENTATION: A 19-year-old woman presented to pulmonary clinic with recurrent episodes of fevers and productive cough over the last 2 years. She was diagnosed with several episodes of respiratory infection that required antibiotic therapy. Her symptoms improved transiently after antibiotic therapy. However, symptoms continued to recur every 1 to 2 months. She denied any close TB contacts or travel outside the United States. She was a nonsmoker and had no history of immunodeficiency. There was no history of cystic fibrosis or any foreign body aspiration.

Variation in Early Management Practices in Moderate-to-Severe ARDS in the United States: The Severe ARDS: Generating Evidence Study.

BACKGROUND: Although specific interventions previously demonstrated benefit in patients with ARDS, use of these interventions is inconsistent, and patient mortality remains high. The impact of variability in center management practices on ARDS mortality rates remains unknown. RESEARCH QUESTION: What is the impact of treatment variability on mortality in patients with moderate to severe ARDS in the United States? STUDY DESIGN AND METHODS: We conducted a multicenter, observational cohort study of mechanically ventilated adults with ARDS and Pao2 to Fio2 ratio of ≤ 150 with positive end-expiratory pressure of ≥ 5 cm H2O, who were admitted to 29 US centers between October 1, 2016, and April 30, 2017. The primary outcome was 28-day in-hospital mortality. Center variation in ventilator management, adjunctive therapy use, and mortality also were assessed. RESULTS: A total of 2,466 patients were enrolled. Median baseline Pao2 to Fio2 ratio was 105 (interquartile range, 78.0-129.0). In-hospital 28-day mortality was 40.7%. Initial adherence to lung protective ventilation (LPV; tidal volume, ≤ 6.5 mL/kg predicted body weight; plateau pressure, or when unavailable, peak inspiratory pressure, ≤ 30 mm H2O) was 31.4% and varied between centers (0%-65%), as did rates of adjunctive therapy use (27.1%-96.4%), methods used (neuromuscular blockade, prone positioning, systemic steroids, pulmonary vasodilators, and extracorporeal support), and mortality (16.7%-73.3%). Center standardized mortality ratios (SMRs), calculated using baseline patient-level characteristics to derive expected mortality rate, ranged from 0.33 to 1.98. Of the treatment-level factors explored, only center adherence to early LPV was correlated with SMR. INTERPRETATION: Substantial center-to-center variability exists in ARDS management, suggesting that further opportunities for improving ARDS outcomes exist. Early adherence to LPV was associated with lower center mortality and may be a surrogate for overall quality of care processes. Future collaboration is needed to identify additional treatment-level factors influencing center-level outcomes. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT03021824; URL: www.clinicaltrials.gov.

Blood DNA methylation and COVID-19 outcomes.

BACKGROUND: There are no prior reports that compare differentially methylated regions of DNA in blood samples from COVID-19 patients to samples collected before the SARS-CoV-2 pandemic using a shared epigenotyping platform. We performed a genome-wide analysis of circulating blood DNA CpG methylation using the Infinium Human MethylationEPIC BeadChip on 124 blood samples from hospitalized COVID-19-positive and COVID-19-negative patients and compared these data with previously reported data from 39 healthy individuals collected before the pandemic. Prospective outcome measures such as COVID-19-GRAM risk-score and mortality were combined with methylation data. RESULTS: Global mean methylation levels did not differ between COVID-19 patients and healthy pre-pandemic controls. About 75% of acute illness-associated differentially methylated regions were located near gene promoter regions and were hypo-methylated in comparison with healthy pre-pandemic controls. Gene ontology analyses revealed terms associated with the immune response to viral infections and leukocyte activation; and disease ontology analyses revealed a predominance of autoimmune disorders. Among COVID-19-positive patients, worse outcomes were associated with a prevailing hyper-methylated status. Recursive feature elimination identified 77 differentially methylated positions predictive of COVID-19 severity measured by the GRAM-risk score. CONCLUSION: Our data contribute to the awareness that DNA methylation may influence the expression of genes that regulate COVID-19 progression and represent a targetable process in that setting.

Plasmodium Ape1 is a multifunctional enzyme in mitochondrial base excision repair and is required for efficient transition from liver to blood stage infection.

The malaria parasite has a single mitochondrion which carries multiple tandem repeats of its 6 kb genome encoding three proteins of the electron transport chain. There is little information about DNA repair mechanisms for mitochondrial genome maintenance in Plasmodium spp. Of the two AP-endonucleases of the BER pathway encoded in the parasite nuclear genome, the EndoIV homolog PfApn1 has been identified as a mitochondrial protein with restricted functions. We explored the targeting and biochemical properties of the ExoIII homolog PfApe1. PfApe1 localized in the mitochondrion and exhibited AP-site cleavage, 3'-5' exonuclease, 3'-phosphatase, nucleotide incision repair (NIR) and RNA cleavage activities indicating a wider functional role than PfApn1. The parasite enzyme differed from human APE1 in possessing a large, disordered N-terminal extension. Molecular modelling revealed conservation of structural domains but variations in DNA-interacting residues and an insertion in the α-8 loop suggested differences with APE1. Unlike APE1, where AP-site cleavage and NIR activities could be mutually exclusive based on pH and Mg2+ ion concentration, PfApe1 was optimally active under similar conditions suggesting that it can function both as an AP-endonuclease in BER and directly cleave damaged bases in NIR under similar physiological conditions. To investigate the role of Ape1 in malaria life cycle, we disrupted the gene by double-cross-over homologous recombination. Ape1 knockout (KO) P. berghei parasites showed normal development of blood and mosquito stages. However, inoculation of mice with Ape1 KO salivary gland sporozoites revealed a reduced capacity to initiate blood stage infection. Ape1 KO parasites underwent normal liver stage development until merozoites egressed from hepatocytes. Our results indicated that the delay in pre-patent period was due to the inability of Ape1 KO merosomes to infect erythrocytes efficiently.

Large-Scale Multi-omic Analysis of COVID-19 Severity.

We performed RNA-seq and high-resolution mass spectrometry on 128 blood samples from COVID-19-positive and COVID-19-negative patients with diverse disease severities and outcomes. Quantified transcripts, proteins, metabolites, and lipids were associated with clinical outcomes in a curated relational database, uniquely enabling systems analysis and cross-ome correlations to molecules and patient prognoses. We mapped 219 molecular features with high significance to COVID-19 status and severity, many of which were involved in complement activation, dysregulated lipid transport, and neutrophil activation. We identified sets of covarying molecules, e.g., protein gelsolin and metabolite citrate or plasmalogens and apolipoproteins, offering pathophysiological insights and therapeutic suggestions. The observed dysregulation of platelet function, blood coagulation, acute phase response, and endotheliopathy further illuminated the unique COVID-19 phenotype. We present a web-based tool (covid-omics.app) enabling interactive exploration of our compendium and illustrate its utility through a machine learning approach for prediction of COVID-19 severity.

Large-scale Multi-omic Analysis of COVID-19 Severity.

We performed RNA-Seq and high-resolution mass spectrometry on 128 blood samples from COVID-19 positive and negative patients with diverse disease severities. Over 17,000 transcripts, proteins, metabolites, and lipids were quantified and associated with clinical outcomes in a curated relational database, uniquely enabling systems analysis and cross-ome correlations to molecules and patient prognoses. We mapped 219 molecular features with high significance to COVID-19 status and severity, many involved in complement activation, dysregulated lipid transport, and neutrophil activation. We identified sets of covarying molecules, e.g., protein gelsolin and metabolite citrate or plasmalogens and apolipoproteins, offering pathophysiological insights and therapeutic suggestions. The observed dysregulation of platelet function, blood coagulation, acute phase response, and endotheliopathy further illuminated the unique COVID-19 phenotype. We present a web-based tool (covid-omics.app) enabling interactive exploration of our compendium and illustrate its utility through a comparative analysis with published data and a machine learning approach for prediction of COVID-19 severity.

Corticosteroid Administration Is Associated With Improved Outcome in Patients With Severe Acute Respiratory Syndrome Coronavirus 2-Related Acute Respiratory Distress Syndrome.

OBJECTIVES: To compare the clinical outcome of mechanically ventilated patients with severe acute respiratory syndrome coronavirus 2-related acute respiratory distress syndrome, who received corticosteroid with those who did not. DESIGN: Retrospective analysis. SETTING: Intensive care setting. PATIENTS: All adult mechanically ventilated patients, who were admitted to the ICU between March 20, 2020, and May 10, 2020, for severe acute respiratory syndrome coronavirus 2-related acute respiratory distress syndrome. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Cohort was divided into two groups based on corticosteroid administration. The primary outcome variable was ventilator-free days at day 28. Secondary outcome variable was ICU-free days at day 30, and hospital-free days at day 30. Consecutive 61 mechanically ventilated patients with severe acute respiratory syndrome coronavirus 2-related acute respiratory distress syndrome were analyzed. Patient in corticosteroid group as compared with noncorticosteroid group have higher 28-day ventilator-free days (mean, 10.2; median, 7 [interquartile range, 0-22.3] vs mean, 4.7; median, 0 [interquartile range, 0-11]; p = 0.01).There was no significant difference noted in secondary outcomes (ICU-free days at day 30 and hospital-free days at day 30). CONCLUSIONS: Among mechanically ventilated severe acute respiratory syndrome coronavirus 2-related acute respiratory distress syndrome patients, corticosteroids use was associated with significant improvement in 28-day ventilator-free days at day 28, but no significant improvement in ICU-free days at day 30, and hospital-free days at day 30.

Granulomatous lung disease: clinical aspects.

INTRODUCTION: Granulomatous lung diseases (GLD) are heterogeneous group of diseases that can be broadly categorized as infectious or noninfectious. This distinction is extremely important, as the misdiagnosis of a GLD can have serious consequences. In this manuscript, we describe the clinical manifestations, histopathology, and diagnostic approach to GLD. We propose an algorithm to distinguish infectious from noninfectious GLD. AREAS COVERED: We have searched PubMed and Medline database from 1950 to December 2019, using multiple keywords as described below. Major GLDs covered include those caused by mycobacteria and fungi, sarcoidosis, hypersensitivity pneumonitis, and vasculidities. EXPERT OPINION: The cause of infectious GLD is usually identified through microbiological culture and molecular techniques. Most noninfectious GLD are diagnosed by clinical and laboratory criteria, often with exclusion of infectious pathogens. Further understanding of the immunopathogenesis of the granulomatous response may allow improved diagnosis and treatment of GLD.

Characterization of ascites-derived aldehyde dehydrogenase-positive ovarian cancer stem cells isolated from Leghorn chickens.

Leghorn chickens are used as a preclinical model of ovarian cancer as they develop epithelial ovarian adenocarcinoma spontaneously at a very high frequency. Ovarian cancer is the most lethal disease among all gynecological malignancies in women. A small proportion of ovarian cancer stem cells are responsible for drug resistance and relapse of ovarian cancer. The objectives of this study are to isolate ovarian cancer stem cells from ascites of Leghorn chickens that spontaneously developed ovarian cancer and to determine their invasiveness, spheroid formation in three-dimensional culture devoid of extracellular matrix over several months. Ovarian cancer cells obtained from ascites were subjected to ALDEFLOUR assay that measures aldehyde dehydrogenase (ALDH) activity to separate ALDH1+ and ALDH1- cells by fluorescence-activated cell sorting. The cells were cultured using serum-free media for up to 6 mo in ultra-low attachment plates. Invasiveness of ALDH1+ and ALDH1- cells was determined by Matrigel invasion assay. Cellular uptake of acetylated low-density lipoprotein was evaluated. A small proportion (<4.75%) of ovarian cancer cells isolated from ascites were found to be ALDH1+ cells. ALDH1+ cells formed a greater number of spheroids and were also highly invasive in extracellular matrix compared to ALDH1- cells. Several spheroids developed 0.1- to 1-mm-long capillary-like tubules connecting other spheroids, thus forming a complex network that underwent remodeling over several months. Cells in the spheroids incorporated acetylated low-density lipoprotein suggestive of scavenger receptor activity. In summary, ALDH1+ ovarian cancer stem cells isolated from ascites of chickens appear to be invasive and form spheroids with complex networks of tubules reminiscent of vascular mimicry. Understanding the structure and function of spheroids and tubular network would provide valuable insight into the biology of ovarian cancer and improve poultry health.

Plasmodium falciparum Apn1 homolog is a mitochondrial base excision repair protein with restricted enzymatic functions.

The malaria parasite carries two organelles, the apicoplast and mitochondrion, whose DNA genomes must be maintained for optimal function and parasite survival under genotoxic stress. DNA repair mechanism(s) operative within these organelles were explored by mining the Plasmodium falciparum nuclear genome for sequences encoding proteins of major DNA repair pathways with predicted targeting to either organelle. Of the panel of enzymes identified for base excision repair (BER), we characterized the apurinic/apyrimidinic (AP) endonuclease PfApn1-an EndoIV whose homolog is not known in humans. PfApn1 targeted to the mitochondrion and functioned as an AP endonuclease requiring both Zn2+ and Mn2+ ions for maximal activity. Mutation of the critical third metal-binding site residue H542 resulted in the loss of Mn2+ (but not Zn2+ ) binding indicating that Mn2+ bound PfApn1 at this site; this was further supported by molecular dynamic simulation. CD spectra analysis further showed requirement of both metal ions for the attainment of PfApn1 ß-strand-rich optimal conformation. PfApn1 also functioned as a 3'-phosphatase that would enable removal of 3'-blocks for DNA polymerase activity during BER. Interestingly, unlike Escherichia coli and yeast EndoIV homologs, PfApn1 lacked 3'-5' exonuclease activity and also did not cleave damaged bases by nucleotide incision repair (NIR). Uncoupling of endonuclease/phosphatase and exonuclease/NIR in PfApn1 suggests that amino acid residues distinct from those critical for endonuclease function are required for exonuclease activity and NIR. Characterization of a critical mitochondrion-targeted AP endonuclease provides evidence for a functional BER pathway in the parasite organelle.

Cannabinoid Oil Vaping-Associated Lung Injury and its Radiographic Appearance.

BACKGROUND: Lung injury associated with cannabinoid oil vaping is rapidly becoming a serious public health concern. We describe the clinical and radiographic presentations of 5 patients with lung injury associated with vaping cannabinoid oils seen at a single institution. RESULTS: Of the 5 patients with suspected vaping-associated lung injury seen at our institution, 4 required supplemental oxygen, and all these 4 were admitted to the hospital. Three patients required admission to the intensive care unit. None of the patients required mechanical ventilation. All patients demonstrated a consistent radiologic appearance of diffuse bilateral ground-glass lung opacities that spared the extreme periphery. Three patients underwent bronchoalveolar lavage, which revealed lipid-laden macrophages in 2 of them. All patients were successfully discharged from the hospital. Four received only supportive care, while the fifth required intravenous followed by oral corticosteroids. CONCLUSIONS: We report the clinical and radiographic presentation of 5 patients at our institution with cannabinoid oil vaping-associated lung injury. All patients displayed a consistent chest radiographic pattern of injury. Most responded to supportive care, although one required the addition of corticosteroids. Bronchoalveolar lavage results suggest that this injury may related to a toxic form of lipoid pneumonia.