The COVID-19 pandemic has had devastating medical and economic consequences globally. The severity of COVID-19 is related, in a large measure, to the extent of pulmonary involvement. The role of chest CT in the management of patients with COVID-19 has evolved since the onset of the pandemic. Specifically, the description of CT findings, use of CT chest in various acute and subacute settings and its usefulness in predicting chronic disease have been better defined. We performed a review of published data on CT scans in COVID-19 patients. A summary of the range of imaging findings, from typical to less common abnormalities is provided. Familiarity with these findings may facilitate in the diagnosis and management of this disease. A comparison of sensitivity and specificity of CT chest with RT-PCR testing highlights the potential role of CT imaging in difficult to diagnose cases of Covid-19. The utility of CT imaging to assess prognosis, guide management, and identify acute pulmonary complications associated with SARS-COV-2 is highlighted. Beyond the acute stage, it is important for clinicians to recognize pulmonary parenchymal abnormalities, progressive fibrotic lung disease and vascular changes that may be responsible for persistent respiratory symptoms. A large collection of multi institutional images has been included to elucidate the CT findings described.

Hypoxia leads to free radical production, which has a pivotal role in the pathophysiology of pulmonary hypertension (PH). We hypothesized that treatment with extracellular superoxide dismutase (EC-SOD) could ameliorate the development of PH induced by hypoxia. In vitro studies using pulmonary microvascular endothelial cells showed that cells transfected with EC-SOD had significantly less accumulation of xanthine oxidase and reactive oxygen species than nontransfected cells after hypoxia exposure for 24 h. To study the prophylactic role of EC-SOD, adult male wild-type (WT) and transgenic (TG) mice, with lung-specific overexpression of human EC-SOD (hEC-SOD), were exposed to fraction of inspired oxygen (FiO 2 ) 10% for 10 d. After exposure, right ventricular systolic pressure (RVSP), right ventricular mass (RV/S + LV), pulmonary vascular wall thickness (PVWT) and pulmonary artery contraction/relaxation were assessed. TG mice were protected against PH compared with WT mice with significantly lower RVSP (23.9 ± 1.24 versus 47.2 ± 3.4), RV/S + LV (0.287 ± 0.015 versus 0.335 ± 0.022) and vascular remodeling, indicated by PVWT (14.324 ± 1.107 versus 18.885 ± 1.529). Functional studies using pulmonary arteries isolated from mice indicated that EC-SOD prevents hypoxia-mediated attenuation of nitric oxide-induced relaxation. Therapeutic potential was assessed by exposing WT mice to FiO 2 10% for 10 d. Half of the group was transfected with plasmid containing cDNA encoding human EC-SOD. The remaining animals were transfected with empty vector. Both groups were exposed to FiO 2 10% for a further 10 d. Transfected mice had significantly reduced RVSP (18.97 ± 1.12 versus 41.3 ± 1.5), RV/S + LV (0.293 ± 0.012 versus 0.372 ± 0.014) and PVWT (12.51 ± 0.72 versus 18.98 ± 1.24). On the basis of these findings, we concluded that overexpression of EC-SOD prevents the development of PH and ameliorates established PH.

. 20-HETE-induced mitochondrial superoxide production and inflammatory phenotype in vascular smooth muscle is prevented by glucose-6-phosphate dehydrogenase inhibition. Am J Physiol Heart Circ Physiol 310: H1107-H1117, 2016. First published February 26, 2016 doi:10.1152/ajpheart.00961.2015 produced by cytochrome P-450 monooxygenases in NA-DPH-dependent manner is proinflammatory, and it contributes to the pathogenesis of systemic and pulmonary hypertension. In this study, we tested the hypothesis that inhibition of glucose-6-phosphate dehydrogenase (G6PD), a major source of NADPH in the cell, prevents 20-HETE synthesis and 20-HETE-induced proinflammatory signaling that promotes secretory phenotype of vascular smooth muscle cells. Lipidomic analysis indicated that G6PD inhibition and knockdown decreased 20-HETE levels in pulmonary arteries as well as 20-HETEinduced 1) mitochondrial superoxide production, 2) activation of mitogen-activated protein kinase 1 and 3, 3) phosphorylation of ETS domain-containing protein Elk-1 that activate transcription of tumor necrosis factor-␣ gene (Tnfa), and 4) expression of tumor necrosis factor-␣ (TNF-␣). Moreover, inhibition of G6PD increased protein kinase G1␣ activity, which, at least partially, mitigated superoxide production and Elk-1 and TNF-␣ expression. Additionally, we report here for the first time that 20-HETE repressed miR-143, which suppresses Elk-1 expression, and miR-133a, which is known to suppress synthetic/secretory phenotype of vascular smooth muscle cells. In summary, our findings indicate that 20-HETE elicited mitochondrial superoxide production and promoted secretory phenotype of vascular smooth muscle cells by activating MAPK1-Elk-1, all of which are blocked by inhibition of G6PD.20-HETE; TNF-␣; elk-1; mitogen-activated protein kinase 1 and 3; extracellular signal regulated kinase 2 and 1; protein kinase G; miRs 20-HYDROXYEICOSATETRAEONIC acid (20-HETE), the -hydroxylation metabolite of arachidonic acid (AA), is produced by cytochrome P-450 monooxygenases of the (CYP4A and CYP4F gene) families in an NADPH-dependent manner (49). 20-HETE is proinflammatory and it regulates vascular and renal function (49). It also plays a critical role in the pathogenesis of systemic hypertension, renal stenosis, and atherosclerosis (27,63,65). 20-HETE increased by hypoxia inhibits hypoxia-induced pulmonary artery constriction (69). However, its role in the hypoxia-induced inflammation of pulmonary arteries or lungs is yet unclear. NEWS & NOTEWORTHY 20-Hydroxyeicosatetraeonic acid (20-HETE) plays a criticalRecently, our laboratory also found that 20-HETE is involved in promoting prolonged hypoxia-induced pulmonary vasoconstriction and that glucose-6-phosphate dehydrogenase (G6PD), which is a major producer of NADPH in the cell, and cytochrome P-450 monooxygenase enzymes are functionally coupled in vascular smooth muscle tissue (unpublished observations). G6PD inhibition relaxes pulmonary arteries by decreasing intracellular calcium (20), prevents switching of vascular smooth ...

Alhawaj R, Patel D, Kelly MR, Sun D, Wolin MS. Heme biosynthesis modulation via ␦-aminolevulinic acid administration attenuates chronic hypoxia-induced pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 308: L719 -L728, 2015. First published February 6, 2015 doi:10.1152/ajplung.00155.2014.-This study examines how heme biosynthesis modulation with ␦-aminolevulinic acid (ALA) potentially functions to prevent 21-day hypoxia (10% oxygen)-induced pulmonary hypertension in mice and the effects of 24-h organoid culture with bovine pulmonary arteries (BPA) with the hypoxia and pulmonary hypertension mediator endothelin-1 (ET-1), with a focus on changes in superoxide and regulation of micro-RNA 204 (miR204) expression by src kinase phosphorylation of signal transducer and activator of transcription-3 (STAT3). The treatment of mice with ALA attenuated pulmonary hypertension (assessed through echo Doppler flow of the pulmonary valve, and direct measurements of right ventricular systolic pressure and right ventricular hypertrophy), increases in pulmonary arterial superoxide (detected by lucigenin), and decreases in lung miR204 and mitochondrial superoxide dismutase (SOD2) expression. ALA treatment of BPA attenuated ET-1-induced increases in mitochondrial superoxide (detected by MitoSox), STAT3 phosphorylation, and decreases in miR204 and SOD2 expression. Because ALA increases BPA protoporphyrin IX (a stimulator of guanylate cyclase) and cGMP-mediated protein kinase G (PKG) activity, the effects of the PKG activator 8-bromo-cGMP were examined and found to also attenuate the ET-1-induced increase in superoxide. ET-1 increased superoxide production and the detection of protoporphyrin IX fluorescence, suggesting oxidant conditions might impair heme biosynthesis by ferrochelatase. However, chronic hypoxia actually increased ferrochelatase activity in mouse pulmonary arteries. Thus, a reversal of factors increasing mitochondrial superoxide and oxidant effects that potentially influence remodeling signaling related to miR204 expression and perhaps iron availability needed for the biosynthesis of heme by the ferrochelatase reaction could be factors in the beneficial actions of ALA in pulmonary hypertension. endothelin; ferrochelatase; guanylate cyclase; micro-RNA 204; superoxide CHRONIC HYPOXIA IS AN IMPORTANT factor in the development of pulmonary hypertension in diseases such as chronic obstructive pulmonary disease (COPD), sleep apnea, and mountain sickness (10,20). It is thought to promote pulmonary hypertension development through persistent pulmonary vasoconstriction and vascular remodeling (31). There is substantial evidence for increases in the generation of reactive oxygen species from sources including Nox oxidases and mitochondria having important roles in the development and/or progression of pulmonary hypertension caused by chronic hypoxia and other stimuli of this disease process (7,15,18,27,30). Pulmonary arterial generation of nitric oxide (NO) is normally thought to oppose this process of vasoconstriction ...

Neo BH, Patel D, Kandhi S, Wolin MS. Roles for cytosolic NADPH redox in regulating pulmonary artery relaxation by thiol oxidation-elicited subunit dimerization of protein kinase G1␣. Am J Physiol Heart Circ Physiol 305: H330 -H343, 2013. First published May 24, 2013 doi:10.1152/ajpheart.01010.2011.-The activity of glucose-6-phosphate dehydrogenase (G6PD) appears to control a vascular smooth muscle relaxing mechanism regulated through cytosolic NADPH oxidation. Since our recent studies suggest that thiol oxidation-elicited dimerization of the 1␣ form of protein kinase G (PKG1␣) contributes to the relaxation of isolated endothelium-removed bovine pulmonary arteries (BPA) to peroxide and responses to hypoxia, we investigated whether cytosolic NADPH oxidation promoted relaxation by PKG1␣ dimerization. Relaxation of BPA to G6PD inhibitors 6-aminonicotinamide (6-AN) and epiandrosterone (studied under hypoxia to minimize basal levels of NADPH oxidation and PKG1␣ dimerization) was associated with increased PKG1␣ dimerization and PKG-mediated vasodilator-stimulated phosphoprotein (VASP) phosphorylation. Depletion of PKG1␣ by small inhibitory RNA (siRNA) inhibited relaxation of BPA to 6-AN and attenuated the increase in VASP phosphorylation. Relaxation to 6-AN did not appear to be altered by depletion of soluble guanylate cyclase (sGC). Depletion of G6PD, thioredoxin-1 (Trx-1), and Trx reductase-1 (TrxR-1) in BPA with siRNA increased PKG1␣ dimerization and VASP phosphorylation and inhibited force generation under aerobic and hypoxic conditions. Depletion of TrxR-1 with siRNA inhibited the effects of 6-AN and enhanced similar responses to peroxide. Peroxiredoxin-1 depletion by siRNA inhibited PKG dimerization to peroxide, but it did not alter PKG dimerization under hypoxia or the stimulation of dimerization by 6-AN. Thus regulation of cytosolic NADPH redox by G6PD appears to control PKG1␣ dimerization in BPA through its influence on Trx-1 redox regulation by the NADPH dependence of TrxR-1. NADPH regulation of PKG dimerization may contribute to vascular responses to hypoxia that are associated with changes in NADPH redox.glucose-6-phosphate dehydrogenase; hypoxia; thioredoxin OUR LABORATORY has previously reported evidence for the existence of a relaxing mechanism coordinated by the oxidation of cytosolic NADPH generated by the pentose phosphate pathway (9) that appeared to participate in the responses of bovine coronary arteries and bovine pulmonary arteries (BPA) to hypoxia (10 -12). Initial studies investigating the mechanism of relaxation to 6-aminonicotinamide (6-AN) and epiandrosterone (Epi), inhibitors of glucose-6-phosphate dehydrogenase (G6PD), in bovine coronary arteries and BPA detected evidence that cytosolic NADPH oxidation appeared to coordinate multiple processes decreasing the levels and actions of intracellular calcium (9,11,12). The inhibition of G6PD by these agents also appeared to lower the detection of reactive oxygen species (ROS) derived from Nox oxidases by decreasing the levels of cytosolic NADPH ...

Oxidation of the soluble guanylate cyclase (sGC) heme promotes loss of regulation by nitric oxide (NO) and depletion of sGC. We hypothesized that angiotensin II (ANG II) stimulation of mitochondrial superoxide by its type 1 receptor could function as a potential inhibitor of heme biosynthesis by ferrochelatase, and this could decrease vascular responsiveness to NO by depleting sGC. These processes were investigated in a 24-h organoid culture model of bovine coronary arteries (BCA) with 0.1 μM ANG II. Treatment of BCA with ANG II increased mitochondrial superoxide, depleted mitochondrial superoxide dismutase (SOD2), ferrochelatase, and cytochrome oxidase subunit 4, and sGC, associated with impairment of relaxation to NO. These processes were attenuated by organoid culture with 8-bromo-cGMP and/or δ-aminolevulinic acid (a stimulator of sGC by protoporphyrin IX generation and heme biosynthesis). Organoid culture with Mito-TEMPOL, a scavenger of mitochondrial matrix superoxide, also attenuated ANG II-elicited ferrochelatase depletion and loss of relaxation to NO, whereas organoid culture with Tempol, an extramitochondrial scavenger of superoxide, attenuated the loss of relaxation to NO by ANG II, but not ferrochelatase depletion, suggesting cytosolic superoxide could be an initiating factor in the loss of sGC regulation by NO. The depletion of cytochrome oxidase subunit 4 and sGC (but not catalase) suggests that sGC expression may be very sensitive to depletion of heme caused by ANG II disrupting ferrochelatase activity by increasing mitochondrial superoxide. In addition, cGMP-dependent activation of protein kinase G appears to attenuate these ANG II-stimulated processes through both preventing SOD2 depletion and increases in mitochondrial and extramitochondrial superoxide.

Endothelial Cell Dysfunction (ECD) is a recognized harbinger of a host of chronic cardiovascular diseases. Using a mouse model of ECD triggered by treatment with L-Nω-methylarginine (L-NMMA), we previously demonstrated that renal microvasculature displays a perturbed protein profile, including diminished expression of two key enzymes of the Krebs cycle associated with a Warburg-type suppression of mitochondrial metabolism. We hypothesized that supplementation with L-glutamine (GLN), that can enter the Krebs cycle downstream this enzymatic bottleneck, would normalize vascular function and alleviate mitochondrial dysfunction. To test this hypothesis, mice with chronic L-NMMA-induced ECD were co-treated with GLN at different concentrations for 2 months. Results confirmed that L-NMMA led to a defect in acetylcholine-induced relaxation of aortic rings that was dose-dependently prevented by GLN. In caveolin-1 transgenic mice characterized by eNOS inactivation, L-NMMA further impaired vasorelaxation which was partially rescued by GLN co-treatment. Pro-inflammatory profile induced by L-NMMA was blunted in mice co-treated with GLN. Using an LC/MS platform for metabolite profiling, we sought to identify metabolic perturbations associated with ECD and offset by GLN supplementation. 3453 plasma molecules could be detected with 100% frequency in mice from at least one treatment group. Among these, 37 were found to be differentially expressed in a 4-way comparison of control vs. LNMMA both with and without GLN. One of such molecules, hippuric acid, an “uremic toxin” was found to be elevated in our non-uremic mice receiving L-NMMA, but normalized by treatment with GLN. Ex vivo analysis of hippuric acid effects on vasomotion demonstrated that it significantly reduced acetylcholine-induced vasorelaxation of vascular rings. In conclusion, functional and metabolic profiling of animals with early ECD revealed macrovasculopathy and that supplementation GLN is capable of improving vascular function. Metabolomic analyses reveal elevation of hippuric acid, which may further exacerbate vasculopathy even before the development of uremia.

The activity of glucose-6-phosphate dehydrogenase (G6PD) controls a vascular smooth muscle relaxing mechanism promoted by the oxidation of cytosolic NADPH, which has been associated with activation of the 1α form of protein kinase G (PKG-1α) by a thiol oxidation-elicited subunit dimerization. This PKG-1α-activation mechanism appears to contribute to responses of isolated endothelium-removed bovine pulmonary arteries (BPA) elicited by peroxide, cytosolic NADPH oxidation resulting from G6PD inhibition, and hypoxia. Dehydroepiandrosterone (DHEA) is a steroid hormone with pulmonary vasodilator activity, which has beneficial effects in treating pulmonary hypertension. Because multiple mechanisms have been suggested for the vascular effects of DHEA and one of the known actions of DHEA is inhibiting G6PD, we investigated whether it promoted relaxation associated with NADPH oxidation, PKG-1α dimerization, and PKG activation detected by increased vasodilator-stimulated phosphoprotein (VASP) phosphorylation. Relaxation of BPA to DHEA under aerobic or hypoxic conditions was associated with NADPH oxidation, PKG-1α dimerization, and increased VASP phosphorylation. The vasodilator activity of DHEA was markedly attenuated in pulmonary arteries and aorta from a PKG knockin mouse containing a serine in place of a cysteine involved in PKG dimerization. DHEA promoted increased PKG dimerization in lungs from wild-type mice, which was not detected in the PKG knockin mouse model. Thus PKG-1α dimerization is a major contributing factor to the vasodilator actions of DHEA and perhaps its beneficial effects in treating pulmonary hypertension.