Poly(L-co-D,L lactic acid-co-Trimethylene Carbonate) 3D printed scaffold cultivated with mesenchymal stem cells directed to bone reconstruction: In vitro and in vivo studies.

A recent and quite promising technique for bone tissue engineering is the 3D printing, peculiarly regarding the production of high-quality scaffolds. The 3D printed scaffold strictly provides suitable characteristics for living cells, in order to induce treatment, reconstruction and substitution of injured tissue. The purpose of this work was to evaluate the behavior of the 3D scaffold based on Poly(L-co-D,L lactic acid-co-Trimethylene Carbonate) (PLDLA-TMC), which was designed in Solidworks™ software, projected in 3D Slicer™, 3D printed in filament extrusion, cultured with mesenchymal stem cells (MSCs) and tested in vitro and in vivo models. For in vitro study, the MSCs were seeded in a PLDLA-TMC 3D scaffold with 600 µm pore size and submitted to proliferation and osteogenic differentiation. The in vivo assays implanted the PLDLA-TMC scaffolds with or without MSCs in the calvaria of Wistar rats submitted to 8 mm cranial bone defect, in periods of 8-12 weeks. The results showed that PLDLA-TMC 3D scaffolds favored adherence and cell growth, and suggests an osteoinductive activity, which means that the material itself augmented cellular differentiation. The implanted PLDLA-TMC containing MSCs, showed better results after 12 weeks prior grafting, due the absence of inflammatory processes, enlarged regeneration of bone tissue and facilitated angiogenesis. Notwithstanding, the 3D PLDLA-TMC itself implanted enriched tissue repair; the addition of cells known to upregulate tissue healing reinforce the perspectives for the PLDLA-TMC applications in the field of bone tissue engineering in clinical trials.

Análisis de las lesiones encefálicas en resonancia magnética en pacientes con señales transitorias de alta intensidad detectadas por Doppler transcraneal / Analysis of Encephalic Lesions in Magnetic Resonance Imaging in patients with High Intensity Transient Signals detected on Transcranial Doppler

Resumen Objetivo: Describir los hallazgos en resonancia magnética (RM) de encéfalo en pacientes menores de 65 años que fueron estudiados por Doppler transcraneal (DTC) con contraste de microburbujas, con antecedentes de accidente cerebrovascular (ACV) criptogénico y sospecha de foramen oval permeable (FOP). Materiales y métodos: Este estudio transversal retrospectivo incluyó pacientes de ambos sexos, menores de 65 años. Resultados: Nuestra muestra (n = 47, 47% masculino y 53% femenino, edad media de 42 años) presentó señales transitorias de alta intensidad (HITS, por su sigla en inglés) positivo en el 61,7% y HITS-negativo en el 38,3%. En pacientes HITS-positivo, predominaron las lesiones a nivel de las fibras en U subcorticales, únicas o múltiples con distribución bilateralmente simétrica. En pacientes con HITS moderados, predominaron las lesiones en el territorio vascular de la circulación posterior. Conclusión: En pacientes menores de 65 años con ACV criptogénico y lesiones en fibras en U subcorticales, únicas o múltiples con distribución bilateral y simétrica, debe tenerse en cuenta un FOP como posible causa de dichas lesiones.

Abstract Objectives: To analyze the findings on brain magnetic resonance imaging (MRI) in patients less than 65 years of age with history of cryptogenic stroke and suspected patent foramen ovale (PFO) who were studied with Contrast-Transcranial Doppler. Materials and Methods: This transversal retrospective study included both, men and women less than 65 years of age. Results: Our sample (n = 47, 47% male and 53% female, average age 42 years old) had High Intensity Transient Signals (HITS)-positive in 61.7% and HITS-negative in 38.3%. In HITS-positive patients, lesions were predominantly located on the subcortical U fibers, lone or multiple bilateral symmetric distributions. In patients with moderate-severity HITS, the posterior circulation was the most affected. Conclusion: In patients less than 65 years of age with cryptogenic stroke with lesions affecting the subcortical U fibers, with unique or multiple bilateral symmetric distributions, a PFO should be considered as an underlying cause.

Structural Characterization of Maize SIRK1 Kinase Domain Reveals an Unusual Architecture of the Activation Segment.

Kinases are primary regulators of plant metabolism and excellent targets for plant breeding. However, most kinases, including the abundant receptor-like kinases (RLK), have no assigned role. SIRK1 is a leucine-rich repeat receptor-like kinase (LRR-RLK), the largest family of RLK. In Arabidopsis thaliana, SIRK1 (AtSIRK1) is phosphorylated after sucrose is resupplied to sucrose-starved seedlings and it modulates the sugar response by phosphorylating several substrates. In maize, the ZmSIRK1 expression is altered in response to drought stress. In neither Arabidopsis nor in maize has the function of SIRK1 been completely elucidated. As a first step toward the biochemical characterization of ZmSIRK1, we obtained its recombinant kinase domain, demonstrated that it binds AMP-PNP, a non-hydrolysable ATP-analog, and solved the structure of ZmSIRK1- AMP-PNP co-crystal. The ZmSIRK1 crystal structure revealed a unique conformation for the activation segment. In an attempt to find inhibitors for ZmSIRK1, we screened a focused small molecule library and identified six compounds that stabilized ZmSIRK1 against thermal melt. ITC analysis confirmed that three of these compounds bound to ZmSIRK1 with low micromolar affinity. Solving the 3D structure of ZmSIRK1-AMP-PNP co-crystal provided information on the molecular mechanism of ZmSIRK1 activity. Furthermore, the identification of small molecules that bind this kinase can serve as initial backbone for development of new potent and selective ZmSIRK1 antagonists.