Hydrogels for Bioprinting: A Systematic Review of Hydrogels Synthesis, Bioprinting Parameters, and Bioprinted Structures Behavior

Nowadays, bioprinting is rapidly evolving and hydrogels are a key component for its success. In this sense, synthesis of hydrogels, as well as bioprinting process, and cross-linking of bioinks represent different challenges for the scientific community. A set of unified criteria and a common framework are missing, so multidisciplinary research teams might not efficiently share the advances and limitations of bioprinting. Although multiple combinations of materials and proportions have been used for several applications, it is still unclear the relationship between good printability of hydrogels and better medical/clinical behavior of bioprinted structures. For this reason, a PRISMA methodology was conducted in this review. Thus, 1,774 papers were retrieved from PUBMED, WOS, and SCOPUS databases. After selection, 118 papers were analyzed to extract information about materials, hydrogel synthesis, bioprinting process, and tests performed on bioprinted structures. The aim of this systematic review is to analyze materials used and their influence on the bioprinting parameters that ultimately generate tridimensional structures. Furthermore, a comparison of mechanical and cellular behavior of those bioprinted structures is presented. Finally, some conclusions and recommendations are exposed to improve reproducibility and facilitate a fair comparison of results.

Frequency and levels of aflatoxin M1 in urine of children in Bogota, Colombia

A study was conducted to investigate the frequency and levels of AFM₁ and AFM₂ in urine from children who attended the emergency service of a pediatric referral hospital in Bogota, Colombia. A survey on the consumption of foods likely to be a source of aflatoxins and on sociodemographic variables was conducted as well. The frequency of AFM₁ in urine was found to be 41.7% with an average concentration in positive samples of 16 pg mL^-1 ± 10.7 pg mL^-1 (range > LOD-48.5 pg mL^-1). The presence of AFM₁ in the urine was related to the consumption of cereals likely to be contaminated with AFB₁, especially corn and rice. No detectable levels of AFM₂ were found in any sample. The results show that children's exposure to aflatoxins in Colombia is indeed a problem and should be one of the priorities of the health authorities. Continuous monitoring of aflatoxins in foods should be carried out, in compliance with Colombian regulations, using analytical methods that allow determination and quantification of aflatoxins in different biological and non-biological matrices at trace levels.

Incidence and prognostic significance of right bundle branch block in patients with acute myocardial infarction receiving thrombolytic therapy

We assessed the incidence and prognostic significance of right bundle branch block (RBBB) in patients with acute myocardial infarction (AMI) receiving thrombolytic therapy. A prospective, one-year follow-up study involving 681 consecutive patients treated with thrombolytic agents for AMI was performed. Seventy-four patients developed RBBB (46% new-onset, 24% old and 30% indeterminate). RBBB was more common in older patients with large anterior AMI. New-onset RBBB were often transient (56%) and 84% of them resolved within 12 h after admission. Complicating events during the hospital phase, such as ventricular arrhythmias and development of heart failure, were more frequent in patients with RBBB. In-hospital and one-year mortality were higher in patients with RBBB (22.9 and 40.5% compared to 7.9 and 12.3% respectively in patients without block, both p<0.001). New-onset, non-transient RBBB were associated with the highest mortality rates (73% at one-year follow-up). By multivariate analysis, RBBB was retained as independent predictor of in-hospital and one-year mortality. We conclude that new-onset RBBB in patients receiving thrombolytic therapy for AMI is often transient. The development of RBBB has a negative and independent prognostic impact on the survival during the hospital phase and at one-year follow-up.