CT-measured pulmonary artery diameter as an independent predictor of pulmonary hypertension in cystic fibrosis

Purpose: The role of computed tomography (CT) scan, as a promising prognostic imaging modality in cystic fibrosis(CF), has been widely investigated, focusing on parenchymal abnormalities. The aim of the present study was to evaluate the diagnostic performance of thoracic vascular parameters on CT to detect pulmonary hypertension (PH). Material and methods: CF patients who contemporaneously underwent CT and echocardiography were retrospectively enrolled. Baseline characteristics in addition to pulmonary artery diameter (PAD) and pulmonary to aortic (PA/A) ratio were compared between cohorts with and without PH, based on the results of echocardiography separately in paediatric patients (< 18) and adults (≥ 18). Results: Of a total 119 CF patients, 39 (32.8%) had PH (paediatric: 23/78, 29.5%, adult: 16/41, 39%). In paediatric CF patients, mean age, HCo3, PCo2, and pulmonary artery diameter (PAD) were significantly higher in the PH group compared to the non-PH group. Mean pulmo however, only PAD remained as the independent predictor of PH based on multivariate analysis (overall: 22.86 mm [±3.86] vs. 18.43 mm [±4.72], p = 0.005, paediatric patients: 22.63 mm [±4.4] vs. 17.10 mm [±4.64], p = 0.03). Using a cut off of 19.25 mm, the diagnostic performance of PAD to detect PH was found to be as follows: sensitivity = 82%, specificity = 70%, and accuracy = 73.1%. No significant difference was demonstrated in PAD between PH and non-PH groups in adults with CF (23.19 [±3.60] vs. 21.34 [±3.49], p = 0.7). Conclusions: In CF patients, PAD revealed an age-dependent performance to detect PH. PAD can be applied to predict pulmonary hypertension in paediatric CF patients and may be recommended to be routinely measured on follow-up chest CT scan in childhood CF

Breast Incidental Lesions at 18 F FDG PET/CT: Diagnostic Performance of PET-derived Metabolic Parameters

Background: Breast incidental lesion at 18 F FDG PET/CT are occasionally encountered in cancer patients, which may represent a second primary malignancy. The aim of the present study was to investigate the diagnostic performance of PET metabolic parameters to characterize breast incidentaloma.Materials and Methods: All the images of patients with cancers other than breast with breast incidental lesion underwent PET/CT scan at Masih Daneshvari Hospital between May 2012 and May 2016 were retrieved and reviewed. SUVmax, SUVmean, MTV and TLG in addition to associated morphologic features on CT and demographics were recorded and correlated with final diagnosis defined by histophatologic confirmation or an at least 1-year clinical formal follow up.Results: Of a total 58 from 51 patients (51/5029, 1.01%), 10 (19.60%) were histopathologically verified as second primary breast cancers. There was a statistically significant difference in SUVmax, SUVmean, MTV and TLG between benign and malignant group (1.64 vs. 5.32 (p=0.009), 1.34 vs. 3.69 (p=0.027), 0.96 vs. 2.62 (p=0.035), 1.54 vs 8.89 (p=0.006). Using cut off 2, 1.35, 1.16 and 1.75, sensitivity and specificity of SUVmax, SUVmean, MTV and TLG were calculated as 77% and 62%, 92% and 66.5%, 77% and 75% 77% and 67%, respectively.Conclusion: Despite a significantly higher value in malignant breast incidental lesion, PET-derivative metabolic parameters provided only modest sensitivity and specificity and hence may not be considered as the sole criteria for risk stratification in this clinical setting

Diagnostic Performance of F-18 FDG PET/CT in Patients with Cancer of Unknown Primary: Additional Benefit over CT-Based Conventional Work up

Background: In the era of well-developed site-specific treatment strategies in cancer, identification of occult primary is of paramount importance in CUP patients. Furthermore, exact determination of the extent of the disease may help in optimizing treatment planning. The aim of the present study was to investigate additional value of F-18 FDG PET/CT in patients with cancer of unknown primary (CUP) as an appropriate imaging tool in early phase of initial standard work up.Materials and Methods: Sixty-two newly diagnosed CUP patients with inconclusive diagnostic CT scan of chest, abdomen and pelvis referring for F-18 FDG PET/CT were enrolled in this study. Standard of reference was defined as histopathology, other diagnostic procedures and a 3-month formal clinical follow up. The results of PET/CT were categorized as suggestion for primary site and additional metastasis and classified as true positive, false positive, false negative and true negative. The impact of additional metastasis revealed by F-18 FDG PET/CT on treatment planning and the time contribution of F-18 FDG PET/CT in diagnostic pathway was investigated.Results: Sixty-two patients with mean age of 62 (30 men, 32 women), PET/CT correctly identified primary origin in 32% with false positive rate of 14.8%. No primary lesion was detected after negative PET/CT according to standard of reference. Sensitivity, Specificity and accuracy were 100%, 78% and 85%, respectively. Additional metastatic site was found in 56% with 22% impact on treatment planning. Time contribution for PET/CT was 10% of total diagnostic pathway.Conclusion: Providing higher detection rate of primary origin with excellent diagnostic performance, shortening the diagnostic pathway and improving treatment planning, F-18 FDG PET/CT may play a major role in diagnostic work up of CUP patients and may be recommended as an alternative imaging tool in early phase of investigation

Brain-Included 18F FDG PET/CT Acquisition Protocol: Cancer-Specified Clinical Impact of Newly-Diagnosed Brain Metastasis in Extra-Cerebral Cancer Patients

Background: Evolution of individualized radiosurgical therapeutic methods for brain metastasis as an ominous prognostic finding may encourage a more extensive application of neuroimaging in patients with extracerebral cancer. The aim of the present study was to investigate the added value of brain-included 18 F FDG PET/CT acquisition protocol based on primary cancer type and clinical indication.Materials and Methods: A retrospective review was performed on 3945 18 F FDG PET/CT reports of patients with extra-cerebral cancer underwent brain-included PET/CT study. Cerebral lesions suggestive of brain metastasis were subsequently verified by MRI, MRI+MRS, surgical pathology and a 1-year clinical formal follow up. The detection rate of new brain metastasis and related impact on disease status were then investigated in each cancer type based on clinical indication.Results: Of a total 3933 eligible patients, 44 (1.12%) were finally verified to have new cerebral metastasis. The most common primary sources were lung cancer (19/385, 4.93%), cancer of unknown primary (CUP) (5/168, 2.97%) and breast cancer (8/468, 1.71%). The most common clinical indications were initial staging (17/44, 43.1%) and restaging (19/44, 36.4%). Change in disease status occurred in 12 out of 44 patients (27.3%), more frequently occurred in lung cancer (n=4), in all indications and breast (n=3) cancers at restaging (n=7, 43.8%).Conclusion: PET/CT acquisition protocol study may be best optimized based on the type of primary cancer and timing of evaluation. Brain-included field of view may be recommended for lung cancer regardless the clinical indication, cancer of unknown primary and breast cancer at restaging

Thermodynamic and Kinetic Study of Carbon Dioxide Hydrogenation on the Metal-Terminated Tantalum-Carbide (111) Surface: A DFT Calculation

The need to reduce our reliance on fossil fuels and lessen the environmentally harmful effects of CO2 have encouraged investigations into CO2 hydrogenation to produce useful products. Transition metal carbides exhibit a high propensity towards CO2 activation, which makes them promising candidates as suitable catalysts for CO2 hydrogenation. Here, we have employed calculations based on the density-functional theory to investigate the reaction network for CO2 hydrogenation to product molecules on the tantalum-terminated TaC (111) surface, including two routes from either HCOOH* or HOCOH* intermediates. Detailed calculations of the reaction energies and energy barriers along multiple potential catalytic pathways, along with the exploration of all intermediates, have shown that CH4 is the predominant product yielded through a mechanism involving HCOOH, with a total exothermic reaction energy of −4.24 eV, and energy barriers between intermediates ranging from 0.126 eV to 2.224 eV. Other favorable products are CO and CH3OH, which are also produced via the HCOOH pathway, with total overall reaction energies of −2.55 and −2.10 eV, respectively. Our calculated thermodynamic and kinetic mechanisms that have identified these three predominant products of the CO2 hydrogenation catalyzed by the TaC (111) surface explain our experimental findings, in which methane, carbon monoxide, and methanol have been observed as the major reaction products

Decreased serum levels of angiotensin converting enzyme (ACE)2 and enhanced cytokine levels with severity of COVID-19: normalisation upon disease recovery

Background:SARS-CoV-2 causes coronavirus disease 2019 (COVID-19). Circulating soluble angiotensin-converting enzyme (sACE2), the main receptor for SARS-CoV-2, together with components of the renin-angiotensin system promote infection and disease severity. Objective: In this pilot study we followed the time-course of sACE2 levels in relation to systemic cytokines in severe and moderate COVID-19 patients treated with remdesivir/dexamethasone in combination. Methods: Peripheral blood was obtained upon admission from 30 patients (12 with moderate disease and 18 with severe disease) and 14 patients with PCR-confirmed mild COVID-19. Severe and moderate patients were treated with remdesivir (200mg/first day and 100mg/day for the remaining days ) and dexamethasone (100mg/day ). 6 healthy control subjects (HC) were also enrolled. Serum interleukin (IL)-6 and IL-8 and sACE2 levels were measured by ELISA at baseline and during treatment in severe and moderate patients and at baseline in mild and HCs. Results: Baseline sACE2 levels were lower in severe (p=0.0005) and moderate (p=0.0022) patients than in patients with mild COVID-19 and in HC (p=0.0023 and p=0.0012 respectively). Serum sACE2 levels increased in patients with severe disease recovered over time compared with moderate (p=0.0021) and severe (p=0.0411) COVID-19 subjects at baseline. Systemic IL-6 and IL-8 levels were higher in all patient groups compared with HC and were not significantly affected over time or by remdesivir/dexamethasone treatment for 5 days. Conclusion: Serum sACE2 levels increase in severe COVID-19 patients as they recover over time whilst circulating cytokines are unaffected. Future studies should link these results to clinical outcomes. Funding: IMA is financially supported by the Welcome Trust (093080/Z/10/Z), the EPSRC (EP/T003189/1), and the Community Jameel Imperial College COVID-19 Excellence Fund (G26290) and by the UK MRC (MR/T010371/1). SM is supported by EU project 853850. Declaration of Interests: The authors declare that there is no conflict of interest to this article. Ethics Approval Statement: The study was approved by the institutional ethics board of the Masih Daneshvari Hospital (Ethics number SBMU.NRITLD.REC.1399.226)

Carbon dioxide hydrogenation over the carbon-terminated niobium carbide (111) surface: a density functional theory study

Carbon dioxide (CO2) hydrogenation is an energetic process which could be made more efficient through the use of effective catalysts, for example transition metal carbides. Here, we have employed calculations based on the density functional theory (DFT) to evaluate the reaction processes of CO2 hydrogenation to methane (CH4), carbon monoxide (CO), methanol (CH3OH), formaldehyde (CH2O), and formic acid (HCOOH) over the carbon-terminated niobium carbide (111) surface. First, we have studied the adsorption geometries and energies of 25 different surface-adsorbed species, followed by calculations of all of the elementary steps in the CO2 hydrogenation process. The theoretical findings indicate that the NbC (111) surface has higher catalytic activity towards CO2 methanation, releasing 4.902 eV in energy. CO represents the second-most preferred product, followed by CH3OH, CH2O, and HCOOH, all of which have exothermic reaction energies of 4.107, 2.435, 1.090, and 0.163 eV, respectively. Except for the mechanism that goes through HCOOH to produce CH2O, all favourable hydrogenation reactions lead to desired compounds through the creation of the dihydroxycarbene (HOCOH) intermediate. Along these routes, CH3* hydrogenation to CH4* has the highest endothermic reaction energy of 3.105 eV, while CO production from HCO dehydrogenation causes the highest exothermic reaction energy of −3.049 eV. The surface-adsorbed CO2 hydrogenation intermediates have minimal effect on the electronic structure and interact only weakly with the surface. Our results are consistent with experimental observations

A Review of Theoretical Studies on Carbon Monoxide Hydrogenation via Fischer–Tropsch Synthesis over Transition Metals

The increasing demand for clean fuels and sustainable products has attracted much interest in the development of active and selective catalysts for CO conversion to desirable products. This review maps the theoretical progress of the different facets of most commercial catalysts, including Co, Fe, Ni, Rh, and Ru. All relevant elementary steps involving CO dissociation and hydrogenation and their dependence on surface structure, surface coverage, temperature, and pressure are considered. The dominant Fischer–Tropsch synthesis mechanism is also explored, including the sensitivity to the structure of H-assisted CO dissociation and direct CO dissociation. Low-coordinated step sites are shown to enhance catalytic activity and suppress methane formation. The hydrogen adsorption and CO dissociation mechanisms are highly dependent on the surface coverage, in which hydrogen adsorption increases, and the CO insertion mechanism becomes more favorable at high coverages. It is revealed that the chain-growth probability and product selectivity are affected by the type of catalyst and its structure as well as the applied temperature and pressure

A Review of Theoretical Studies on Carbon Monoxide Hydrogenation via Fischer–Tropsch Synthesis over Transition Metals

The increasing demand for clean fuels and sustainable products has attracted much interest in the development of active and selective catalysts for CO conversion to desirable products. This review maps the theoretical progress of the different facets of most commercial catalysts, including Co, Fe, Ni, Rh, and Ru. All relevant elementary steps involving CO dissociation and hydrogenation and their dependence on surface structure, surface coverage, temperature, and pressure are considered. The dominant Fischer–Tropsch synthesis mechanism is also explored, including the sensitivity to the structure of H-assisted CO dissociation and direct CO dissociation. Low-coordinated step sites are shown to enhance catalytic activity and suppress methane formation. The hydrogen adsorption and CO dissociation mechanisms are highly dependent on the surface coverage, in which hydrogen adsorption increases, and the CO insertion mechanism becomes more favorable at high coverages. It is revealed that the chain-growth probability and product selectivity are affected by the type of catalyst and its structure as well as the applied temperature and pressure

A first-principles study of CO2 hydrogenation on a Niobium-Terminated NbC (111) surface

As promising materials for the reduction of greenhouse gases, transition-metal carbides, which are highly active in the hydrogenation of CO2, are mainly considered. In this regard, the reaction mechanism of CO2 hydrogenation to useful products on the Nb-terminated NbC (111) surface is investigated by applying density functional theory calculations. The computational results display that the formation of CH4, CH3OH, and CO are more favored than other compounds, where CH4 is the dominant product. In addition, the findings from reaction energies reveal that the preferred mechanism for CO2 hydrogenation is thorough HCOOH*, where the largest exothermic reaction energy releases during the HCOOH* dissociation reaction (2.004 eV). The preferred mechanism of CO2 hydrogenation towards CH4 production is CO2*→t,c-COOH*→HCOOH*→HCO*→CH2O*→CH2OH*→CH2*→CH3*→CH4*, where CO2*→t,c-COOH*→HCOOH*→HCO*→CH2O*→CH2OH*→CH3OH* and CO2*→t,c-COOH*→CO* are also found as the favored mechanisms for CH3OH and CO productions thermodynamically, respectively. During the mentioned mechanisms, the hydrogenation of CH2O* to CH2OH* has the largest endothermic reaction energy of 1.344 eV