Age-determined expression of priming protease TMPRSS2 and localization of SARS-CoV-2 in lung epithelium

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) novel coronavirus 2019 (COVID-19) global pandemic has led to millions of cases and hundreds of thousands of deaths. While older adults appear at high risk for severe disease, hospitalizations and deaths due to SARS-CoV-2 among children have been relatively rare. Integrating single-cell RNA sequencing (scRNA-seq) of developing mouse lung with temporally resolved immunofluorescence in mouse and human lung tissue, we found that expression of SARS-CoV-2 Spike protein primer TMPRSS2 was highest in ciliated cells and type I alveolar epithelial cells (AT1), and TMPRSS2 expression increased with aging in mice and humans. Analysis of autopsy tissue from fatal COVID-19 cases detected SARS-CoV-2 RNA most frequently in ciliated and secretory cells in airway epithelium and AT1 cells in peripheral lung. SARS-CoV-2 RNA was highly colocalized in cells expressing TMPRSS2. Together, these data demonstrate the cellular spectrum infected by SARS-CoV-2 in lung epithelium and suggest that developmental regulation of TMPRSS2 may underlie the relative protection of infants and children from severe respiratory illness.     

Use of the composite asthma severity index in a pediatric subspecialty clinic

BackgroundThe Composite Asthma Severity Index (CASI) is a comprehensive tool to assess asthma severity, which has been applied in the research setting.ObjectiveTo evaluate, in an outpatient setting, whether a CASI score accurately predicts asthma severity or control as determined by means of subspecialist assessment. Asthma Control Test (ACT) and childhood ACT (C-ACT) scores were generated to provide additional context for CASI scores in relationship to assessments using another clinical tool.MethodsChildren aged 5 to 18 years with a physician diagnosis of persistent asthma were recruited from a tertiary care center. A pediatric pulmonologist made determinations on each participant’s asthma severity and control during a clinic visit. A CASI and ACT/C-ACT score was generated for each patient. Logistic regression and Spearman correlations were used to determine how well CASI scores predicted physician assessments. Agreement between ACT/C-ACT scores and physician assessment of asthma control was determined in supplemental analyses.ResultsCASI scores strongly predicted physician assessment of severity (Spearman correlation = 0.61, P < .001); unadjusted odds ratio (OR) equal to 36.67 (95% confidence interval [CI]: 8.83-152.34); and adjusted OR equal to 32.76 (95% CI: 85.70-188.44). In supplemental analyses, ACT/C-ACT scores strongly predicted physician assessment of control (Spearman correlation = 0.72, P < .001) with an unadjusted OR equal to 42.12 (95% CI: 13.34-133.00) and adjusted OR equal to 55.34 (95% CI: 13.62-224.89).ConclusionUse of the CASI was feasible and accurately predicted physician assessments of asthma severity and control in this sample, which are not distinct entities. The CASI is a robust tool that may be used successfully in ambulatory pediatric asthma care.     

Aging and heart failure--similar syndromes of exercise intolerance? Implications for exercise-based interventions

A classic hallmark of chronic heart failure (CHF) is exercise intolerance; however, the extent of exercise limitation is not correlated with the degree of left ventricular dysfunction. Over the past 2 decades it has become more and more evident that peripheral factors, such as skeletal muscle dysfunction, ventilatory abnormalities, and endothelial dysfunction, contribute the greater part to the limitation of exercise capacity. The molecular and pathophysiological changes observed in these organ systems are not always specific to the underlying CHF but rather represent a common pathway that is activated in several chronic disease processes, including severe chronic obstructive pulmonary disease, cancer, and in the normal aging process. A major contributing factor for skeletal muscle catabolism (i.e. elevated cytokine expression in the skeletal muscle) can be found in both normal healthy aging and in heart failure patients. It is reasonable to assume that the overlap of aging and CHF-associated changes in the skeletal muscle partially explains the disabling consequences of the CHF syndrome among elderly patients (nearly 80% of all patients hospitalized for CHF are >65 years old). Peripheral alterations in CHF are often not adequately treated in routine clinical care since standard pharmacological therapy is still focused on the cardiac function and neurohormonal alteration. Exercise training is a guideline-oriented adjuvant therapy with well-documented beneficial effects on exercise tolerance, skeletal muscle function, endothelial function, and respiration. In this review, the effects of exercise in aging and in CHF are compared and the parallel mechanisms are explored.     

Comparative molecular modeling of Anopheles gambiae CYP6Z1, a mosquito P450 capable of metabolizing DDT

One of the challenges faced in malarial control is the acquisition of insecticide resistance that has developed in mosquitoes that are vectors for this disease. Anopheles gambiae, which has been the major mosquito vector of the malaria parasite Plasmodium falciparum in Africa, has over the years developed resistance to insecticides including dieldrin, 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), and pyrethroids. Previous microarray studies using fragments of 230 An. gambiae genes identified five P450 loci, including CYP4C27, CYP4H15, CYP6Z1, CYP6Z2, and CYP12F1, that showed significantly higher expression in the DDT-resistant ZAN/U strain compared with the DDT-susceptible Kisumu strain. To predict whether either of the CYP6Z1 and CYP6Z2 proteins might potentially metabolize DDT, we generated and compared molecular models of these two proteins with and without DDT docked in their catalytic sites. This comparison indicated that, although these two CYP6Z proteins share high sequence identity, their metabolic profiles were likely to differ dramatically from the larger catalytic site of CYP6Z1, potentially involved in DDT metabolism, and the more constrained catalytic site of CYP6Z2, not likely to metabolize DDT. Heterologous expressions of these proteins have corroborated these predictions: only CYP6Z1 is capable of metabolizing DDT. Overlays of these models indicate that slight differences in the backbone of SRS1 and variations of side chains in SRS2 and SRS4 account for the significant differences in their catalytic site volumes and DDT-metabolic capacities. These data identify CYP6Z1 as one important target for inhibitor design aimed at inactivating insecticide-metabolizing P450s in natural populations of this malarial mosquito.     

Use of a water-soluble busulfan formulation--pharmacokinetic studies in a canine model

In a canine model we investigated the toxicity and pharmacokinetics of a water soluble busulfan preparation. Busulfan was dissolved in dimethylsulfoxide (DMSO) and administered either orally or intravenously in a single dose of 1 mg/kg. The application in either preparation was well tolerated. In seven dogs, peak levels in the range of 730 ng/mL to 1,000 ng/mL were measured after intravenous injection with an area under curve (AUC) of 75 ng.h/kg.mL to 146 ng.h/kg.mL. It was of note that even the oral administration of the same busulfan preparation resulted in AUC values in the same range as observed after parenteral application. The absorption rate of busulfan tablets in our model was as unpredictable as documented in clinical trials. On the basis of the present study, clinical trials using busulfan dissolved in DMSO given either intravenously or orally appear warranted. This approach should lead to predictable blood levels, reduced toxicity, and increased efficacy of busulfan-containing regimens.     

Prognostic Significance of Remote Myocardium Alterations Assessed by Quantitative Noncontrast T1 Mapping in ST-Segment Elevation Myocardial Infarction

Objectives

This study assessed the prognostic significance of remote zone native T1 alterations for the prediction of clinical events in a population with ST-segment elevation myocardial infarction (STEMI) who were treated by primary percutaneous coronary intervention (PPCI) and compared it with conventional markers of infarct severity.

CMR–Derived Extracellular Volume Fraction as a Marker for Myocardial Fibrosis: The Importance of Coexisting Myocardial Inflammation

Objectives

The aim of the present study was to evaluate whether extracellular volume fraction (ECV) can reliably inform on the extent of diffuse fibrosis in the simultaneous presence of myocardial inflammation, which has not been verified to date.

Contribution of Clinically Derived Mutations in ERG11 to Azole Resistance in Candida albicans

In Candida albicans, the ERG11 gene encodes lanosterol demethylase, the target of the azole antifungals. Mutations in ERG11 that result in an amino acid substitution alter the abilities of the azoles to bind to and inhibit Erg11, resulting in resistance. Although ERG11 mutations have been observed in clinical isolates, the specific contributions of individual ERG11 mutations to azole resistance in C. albicans have not been widely explored. We sequenced ERG11 in 63 fluconazole (FLC)-resistant clinical isolates. Fifty-five isolates carried at least one mutation in ERG11, and we observed 26 distinct positions in which amino acid substitutions occurred. We mapped the 26 distinct variant positions in these alleles to four regions in the predicted structure for Erg11, including its predicted catalytic site, extended fungus-specific external loop, proximal surface, and proximal surface-to-heme region. In total, 31 distinct ERG11 alleles were recovered, with 10 ERG11 alleles containing a single amino acid substitution. We then characterized 19 distinct ERG11 alleles by introducing them into the wild-type azole-susceptible C. albicans SC5314 strain and testing them for susceptibilities to FLC, itraconazole (ITC), and voriconazole (VRC). The strains that were homozygous for the single amino acid substitutions Y132F, K143R, F145L, S405F, D446E, G448E, F449V, G450E, and G464S had a ≥4-fold increase in FLC MIC. The strains that were homozygous for several double amino acid substitutions had decreased azole susceptibilities beyond those conferred by any single amino acid substitution. These findings indicate that mutations in ERG11 are prevalent among azole-resistant clinical isolates and that most mutations result in appreciable changes in FLC and VRC susceptibilities.