Circular RNAs (circRNAs) are a class of non-coding RNAs that are generated via alternative back-splicing, which connects the terminal 5′ and 3′ends. Due to their unique loop structure, circRNAs are resistant to ribonucleases and more stable than linear RNAs. In vivo, they are usually highly conserved and stably expressed in tissue/developmental-stage-specific manners. Generally, circRNAs function as microRNA sponges and splicing regulators, as well as in protein binding and transcription. Some circRNAs contain open reading frames with internal ribosomal entry site elements and can thus encode specific proteins. Previously, circRNAs were thought to be erroneous splicing products or by-products of mRNA splicing. With the development of the next-generation sequencing techniques, it has become increasingly clear that circRNAs are abundantly widespread in eukaryotes and that they play significant roles in malignant tumor progression. The present review briefly introduces the biogenesis and functions of circRNAs, as well as summarizes recent research in several common malignancies. The present review also addresses the prospects of circRNAs in clinical applications.

Background and purpose: Multiple randomized trials have confirmed that mechanical thrombectomy (MT) is an effective treatment method for patients with acute ischemic stroke (AIS). However, evidence on the safety and efficacy of MT in elderly patients compared with younger patients is controversial. This meta-analysis is aimed to systematically compare the outcomes of elderly patients and younger patients after MT for AIS.Methods: A systematic literature search was conducted through the PubMed, EMBASE, and Cochrane Library database. The primary outcomes were favorable functional outcome at 90 days and mortality. The secondary outcomes were symptomatic intracerebral hemorrhage (sICH) and successful recanalization rate. Odds ratios (ORs) were estimated using a random effects model. Results: Sixteen studies published between 2014 and 2019 were included in this meta-analysis totally involving 3,954 patients. The pooled results showed that patients aged ≥80 years had worse functional outcome (OR = 0.40; 95% CI, 0.32-0.50; P < 0.001) and higher rates of mortality (OR = 2.26; 95% CI, 1.73-2.95; P < 0.001). There was a trend of higher rates of sICH in patients aged ≥80 years compared with patients aged <80 years, whereas this did not reach statistical significance (OR = 1.28; 95% CI, 0.89-1.84; P = 0.18). Furthermore, the frequency of successful recanalization was also lower in patients aged ≥80 years compared with patients aged <80 years (OR = 0.72; 95% CI, 0.55-0.95; P = 0.02). The subgroup analysis indicated that in comparison with those studies published between 2014 and 2016, elderly patients undergoing MT had better outcomes in studies published between 2017 and 2019.Conclusion: Elderly patients undergoing MT had higher risk of mortality and worse functional outcome. Meanwhile, there was a trend toward higher rates of sICH and lower probability of achieving successful recanalization in elderly patients. These findings emphasize the need for improving the rates of successful recanalization in elderly patients Zhao et al.Mechanical Thrombectomy for Ischemic Stroke in Octogenarians with AIS. In addition, advanced technology of endovascular intervention and peri-interventional management might be associated with the prognosis in elderly patients. However, more prospective or randomized studies should be conducted to further explore this issue.

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Background and Purpose: The lifetime prevalence of benign paroxysmal positional vertigo (BPPV) is high, especially in the elderly. Patients with BPPV are more susceptible to ischemic stroke, dementia, and fractures, severely reducing quality of life of patients. Many studies have analyzed risk factors for the occurrence of BPPV. However, the results of these studies are not identical. We performed this meta-analysis to determine potential risk factors associated with the occurrence of BPPV. Methods: PubMed, EMBASE, and the Cochrane Library (January 2000 through March 2020) were systematically searched for eligible studies analyzing risk factors for the occurrence of BPPV. Reference lists of eligible studies were also reviewed. We selected observational studies in English with a control group and sufficient data. Pooled odds ratios (ORs) or the mean differences (MDs) and 95% confidence intervals (CIs) were calculated to measure the impacts of all potential risk factors. Heterogeneity among studies was evaluated using the Q-test and I 2 statistics. We used the randomeffect model or the fixed-effect model according to the heterogeneity among the included studies. Results: We eventually included 19 studies published between 2006 and 2019, including 2,618 patients with BPPV and 11,668 participants without BPPV in total. In this meta-analysis, the occurrence of BPPV was significantly associated with female gender (OR = 1.18; 95% CI, 1.05-1.32; P = 0.004), serum vitamin D level (MD = −2.12; 95% CI, −3.85 to −0.38; P = 0.02), osteoporosis (OR = 2.49; 95% CI, 1.39-4.46; P = 0.002), migraine (OR = 4.40; 95% CI, 2.67-7.25; P < 0.00001), head trauma (OR = 3.42; 95% CI, 1.21-9.70; P = 0.02), and total cholesterol level (MD = 0.32; 95% CI, 0.02-0.62; P = 0.03). Conclusion: Female gender, vitamin D deficiency, osteoporosis, migraine, head trauma, and high TC level were risk factors for the occurrence of BPPV. However, the effects of other risk factors on BPPV occurrence need further investigations.

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