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Recent studies on the pathophysiology of COVID-19 are indicating that the Angiotensin convertase enzyme 2 (ACE-2) and transmembrane serine protease 2 (TMPRSS2) can act as a major component in the fusion of SARS-Cov-2 with target cells. It has also been observed that the expression of ACE-2 and TMPRSS2 can be altered in malignancies. Shedding light on this matter could be crucial since the COVID-19 pandemic interfered with many gastrointestinal cancer screening programs. Herein we discuss the possibility of severe forms of COVID-19 in patients with gastrointestinal cancers due to the gastrointestinal entry route of SARS-CoV-2 into the human body. The disruption of cancer screening programs caused by the current COVID-19 pandemic could therefore have massive negative health impact on patients affected by gastrointestinal malignancies.

IntroductionDiabetic retinopathy (DR) is a medical condition caused by damage to the blood vessels of retina tissue due to diabetes mellitus. DR leads to injury in neural and vascular structures and is reported to be significantly influenced by inflammation and inflammatory mediators like cytokines. In this study, a systematic review and meta-analysis were performed to analyze the association between cytokine gene polymorphisms and DR.MethodsWe identified relevant studies from Scopus, PubMed, and Google scholar databases. Allele and genotype frequencies were pooled. Heterogeneity and publication bias were explored. The odds ratio (OR) and corresponding 95% confidence intervals (CIs) were calculated to estimate the relation.ResultsA total of 3337 cases and 4945 controls in 19 eligible studies were included in the meta-analysis. Overall, results indicated the negative association between the cytokine gene polymorphisms and DR susceptibility in the allelic model (IFN-γ (rs2430561): OR 0.64, [CI]: 0.5 to 0.82; and TGF-β (rs1800471): [OR] = 0.15, [CI]: 0.03 to 0.79); and also, in the dominant model (IFN-γ (rs2430561): OR = 0.4, [CI]: 0.22 to 0.75; and TGF-β (rs1800471): OR = 0.14, [CI]: 0.05 to 0.4).ConclusionThe present study suggests that IFN-γ (rs2430561) and TGF-β (rs1800471) polymorphisms are associated with decreased susceptibility to DR.

BackgroundApproximately 20% of all transient ischaemic attacks (TIAs) and ischaemic strokes occur within the posterior circulation, with vertebrobasilar stenosis identified as the cause in roughly 25% of the cases. Studies have shown that about a quarter of these patients have atherosclerotic stenosis of at least 50% of the vertebrobasilar artery. Stenosis has been shown to be associated with an increased risk of 90-day recurrent vertebrobasilar stroke, particularly in the first few weeks, which is significantly higher when compared with patients with stenosis of the anterior circulation. Therefore, aggressive treatment is important for the patient’s prognosis. Stenting is emerging as a promising therapeutic strategy for persistent ischaemia events that do not respond to the best medical treatment, but it is not without complications. We systematically reviewed the literature on percutaneous transluminal angioplasty and stenting (PTAS) for intracranial vertebrobasilar artery stenosis (IVBS).MethodsPubMed, Web-of-Science and Scopus were searched upon the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to include prospective/retrospective cohort, randomised/non-randomised clinical trials and case series studies describing PTAS for IVBS. Pooled rates of intervention-related complications and outcomes were analysed with random-effect model meta-analysis using StataMP V.18.0 software.Results31 studies were found eligible which included 1928 cases. 1103 basilar artery stenosis cases were reported in 27 studies 0.65 (95% CI 0.53, 0.76), I2: 99.72%. 648 vertebral cases were reported in 18 studies 0.60 (95% CI 0.49, 0.70), I2: 97.49%. In four studies, the rate of vertebrobasilar stenosis cases calculated as a proportion of the total sample size was 0.10 (95% CI 0.05, 0. 15). Mean stenosis in 21 included studies was found to be 0.83 (95% CI 0.79, 0.88), I2: 0.00%, which shows variation of baseline stenosis between studies was minimal. 51 deaths were recorded in 24 studies. Meta-analysis of mortality showed the overall rate of mortality was 0.03 (95% CI 0.02, 0.05), I2: 44.90%. In 14 studies, symptomatic intracranial haemorrhage events were recorded at an overall rate of 0.01 (95% CI 0.00, 0.02), I2: 0.00%. Generally, a follow-up period of at least 3 months was reported in the included studies. Furthermore, procedural stroke/TIA was evaluated in seven studies, four of which reported no events (0.03 (95% CI 0.00, 0.08), I2: 20.38%). Mean time from initial symptoms to recanalisation was 23.98 (95% CI 18.56, 29.40), I2=98.8%, p=0.00 days.ConclusionIn certain individuals with medically unresolved, severe, symptomatic and non-acute IVBS, elective vertebrobasilar PTAS appears to be both safe and effective. Various stent designs and angioplasty-assisted techniques should be taken into consideration based on the specific clinical and radiological traits of the lesions. Future randomised controlled trials are required to verify these results.

Double-layer graphene nanoribbons promise potential application in nanoelectromechanical systems and optoelectronic devices, and knowledge about mechanical stability is a crucial parameter to flourish the application of these materials at the next generation of nanodevices. In this paper, molecular mechanics is utilized to investigate nonlinear buckling behavior, critical buckling stress, and lateral deflection of double-layered graphene nanoribbons under various configurations of stacking mode and chirality. The implicit arc-length iterative method (modified Riks method) with Ramm’s algorithm is utilized to analyze the nonlinear structural stability problem. The covalent bonds are modeled using three-dimensional beam elements in which elastic moduli are calculated based on molecular structural mechanics technique, and the interlayer van der Waals (vdW) interactions are modeled with nonlinear truss elements. An analytical expression for Young’s modulus of nonlinear truss elements is derived based on the Lennard–Jones potential function and implemented in numerical simulation with a UMAT subroutine based on FORTRAN code to capture the nonlinearity of the vdW interactions during the buckling analysis. The results indicate that the highest critical buckling stress and the minimum lateral deflection occur for armchair and zigzag chirality, both with AB stacking mode, respectively. Moreover, the critical buckling stress is found to be directly dependent on the mode shape number regardless of in-phase or anti-phase deflection direction of layers. Lateral deflection exhibits a similar trend with mode shape in anti-phase mode; however, it is decreasing by increasing mode shape number in in-phase mode.