Engineering self-organized criticality in living cells.

Complex dynamical fluctuations, from intracellular noise, brain dynamics or computer traffic display bursting dynamics consistent with a critical state between order and disorder. Living close to the critical point has adaptive advantages and it has been conjectured that evolution could select these critical states. Is this the case of living cells? A system can poise itself close to the critical point by means of the so-called self-organized criticality (SOC). In this paper we present an engineered gene network displaying SOC behaviour. This is achieved by exploiting the saturation of the proteolytic degradation machinery in E. coli cells by means of a negative feedback loop that reduces congestion. Our critical motif is built from a two-gene circuit, where SOC can be successfully implemented. The potential implications for both cellular dynamics and behaviour are discussed.

Synthetic Lateral Inhibition in Periodic Pattern Forming Microbial Colonies.

Multicellular entities are characterized by intricate spatial patterns, intimately related to the functions they perform. These patterns are often created from isotropic embryonic structures, without external information cues guiding the symmetry breaking process. Mature biological structures also display characteristic scales with repeating distributions of signals or chemical species across space. Many candidate patterning modules have been used to explain processes during development and typically include a set of interacting and diffusing chemicals or agents known as morphogens. Great effort has been put forward to better understand the conditions in which pattern-forming processes can occur in the biological domain. However, evidence and practical knowledge allowing us to engineer symmetry-breaking is still lacking. Here we follow a different approach by designing a synthetic gene circuit in E. coli that implements a local activation long-range inhibition mechanism. The synthetic gene network implements an artificial differentiation process that changes the physicochemical properties of the agents. Using both experimental results and modeling, we show that the proposed system is capable of symmetry-breaking leading to regular spatial patterns during colony growth. Studying how these patterns emerge is fundamental to further our understanding of the evolution of biocomplexity and the role played by self-organization. The artificial system studied here and the engineering perspective on embryogenic processes can help validate developmental theories and identify universal properties underpinning biological pattern formation, with special interest for the area of synthetic developmental biology.

Sclerosing Pneumocytoma Presenting as Endobronchial Tumor With Negative Autofluorescence / Tumor endobronquial con autofluorescencia negativa: Neumocitoma esclerosante

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Free-floating right heart thrombus with pulmonary embolism in SARS-CoV-2 patient / Trombo intracardíaco con tromboembolia pulmonar en paciente con SARS-CoV-2

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Traqueobroncopatía osteocondroplástica / Tracheobronchopathia osteochondroplastica

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Grado de dolor al pinchar la fistula arteriovenosa con agujas congeladas comparando con agujas a temperatura ambiente / Level of pain in the arteriovenous fistula comparing frozen needles with room temperature needles

El dolor es una sensación subjetiva de malestar o sufrimiento que se origina como resultado de estimulaciones nocivas que indican daño tisular o enfermedad de cualquier tipo. Ocupa un lugar preeminente entre todas las experiencias sensoriales por medio de las cuales el hombre es consciente de que padece una enfermedad o está sufriendo una agresión externa, provocada por otra persona, sobre alguna parte de su cuerpo al realizar un tratamiento médico, produciendo dolor agudo. El objetivo principal del trabajo es comparar el grado de dolor al que es sometido el paciente cuando se punciona su fístula arteriovenosa (FA-VI) con agujas a distinta temperatura. El número de pacientes fueron 25. Las variables estudiadas: edad, sexo y tipo de acceso vascular no han sido estadísticamente significativas, por el contrario, en la comparación entre agujas a - 8°C y agujas a temperatura ambiente, si existe diferencia significativa en la intensidad del dolor que siente el paciente (AU)