Reduction of cortical pulling at mitotic entry facilitates aster centration.

Equal cell division relies upon astral microtubule-based centering mechanisms, yet how the interplay between mitotic entry, cortical force generation and long astral microtubules leads to symmetric cell division is not resolved. We report that a cortically located sperm aster displaying long astral microtubules that penetrate the whole zygote does not undergo centration until mitotic entry. At mitotic entry, we find that microtubule-based cortical pulling is lost. Quantitative measurements of cortical pulling and cytoplasmic pulling together with physical simulations suggested that a wavelike loss of cortical pulling at mitotic entry leads to aster centration based on cytoplasmic pulling. Cortical actin is lost from the cortex at mitotic entry coincident with a fall in cortical tension from ∼300pN/µm to ∼100pN/µm. Following the loss of cortical force generators at mitotic entry, long microtubule-based cytoplasmic pulling is sufficient to displace the aster towards the cell center. These data reveal how mitotic aster centration is coordinated with mitotic entry in chordate zygotes.

Disección de aorta secundario a trauma, manejo clínico en Hospital General / Aortic dissection secondary to trauma, clinical management in General Hospital

INTRODUCCIÓN. La disección de aorta es una patología poco frecuente, cuando se presenta, lo hace de una manera catastrófica manifestada por dolor torácico o lumbar intenso acompañado de compromiso hemodinámico agudo, un diagnóstico y tratamiento temprano suelen ser cruciales para evitar la muerte del paciente, así mismo, una disección de aorta puede ser secundario a un trauma torácico por desaceleración y se presenta en 1,5% a 2%, lo que induce sobre todo a un desgarro localizado en la región del istmo aórtico. CASO CLÍNICO. Paciente masculino de 35 años, con antecedente de accidente en vehículo motorizado que provocó un traumatismo cráneo encefálico moderado, hematoma epidural parietal derecho, con resolución quirúrgica hace 18 meses, se descartó lesiones a nivel de tórax con radiografía de tórax normal, además se realizó ecografía FAST en ventana perihepática, suprapúbica, periesplénica y subxi-foidea sin encontrar alteración. Acudió al servicio de emergencia por un cuadro de hemiparesia derecha más disartria de 4 horas de evolución, se realiza tomografía de cráneo sin encontrarse lesión, catalogándose como evento cerebrovascular isquémico con recuperación neurológica. Durante su estancia hospitalaria presenta un cuadro de disnea de grandes esfuerzos y tras realizar exámenes complementarios de control se llega a una conclusión de una cardiomegalia, por lo que es referido a consulta de cardiología donde se realiza ecocardiograma, en la cual se observa disección de aorta ascendente más aneurisma por lo que se decide su ingreso y se instaura tratamiento mediante medidas de soporte, con derivación a hospital de especialidades para cirugía cardiotorácica. CONCLUSIONES. La disección de aorta secundario a un traumatis-mo es poco frecuente, sin embargo, el diagnostico siempre debe estar presente en caso de trauma por desaceleración, ya que es vital para la supervivencia del paciente y su manejo oportuno.

INTRODUCTION. Aortic dissection is an infrequent pathology; when it occurs, it does so in a catastrophic manner manifested by intense thoracic or lumbar pain accompanied by acute he-modynamic compromise. Early diagnosis and treatment are usually crucial to avoid the patient's death; likewise, aortic dissection can be secondary to thoracic trauma due to deceleration and occurs in 1.5% to 2%, which mainly induces a localized tear in the region of the aortic isthmus. CLINICAL CASE. 35-year-old male patient, with a history of motor vehicle accident that caused a moderate head injury, right parietal epidural hematoma, with surgical resolution 18 months ago, chest injuries were ruled out with normal chest X-ray, and FAST ultrasound was performed in perihepatic, suprapubic, perisplenic and subxiphoid window without finding any alteration. She went to the emergency department for a picture of right hemiparesis and dysarthria of 4 hours of evolution, a cranial tomography was performed without finding any lesion, being clas-sified as an ischemic cerebrovascular event with neurological recovery. During his hospital stay he presented with dyspnea of great effort and after performing complementary control tests, a cardiomegaly was found, so he is referred to a cardiology clinic where an echocardiogram is per-formed, which showed dissection of the ascending aorta plus aneurysm, admission is decided and treatment is instituted through supportive measures, with referral to a specialty hospital for cardiothoracic surgery. CONCLUSIONS. Aortic dissection secondary to trauma is rare, however, the diagnosis should always be present in case of trauma due to deceleration, as it is vital for the survival of the patient and its timely treatment.

Repair of long-bone pseudoarthrosis with autologous bone marrow mononuclear cells combined with allogenic bone graft.

BACKGROUND AIMS: Long-bone pseudoarthrosis is a major orthopedic concern because of numerous factors such as difficulty of the treatment, high recurrence, high costs and the devastating effects on the patients' quality of life, which sometimes ends in amputation. Although the "gold standard" for the treatment of this pathology is autologous bone grafting, which has high osteogenic, osteoconductive and osteoinductive properties, this treatment presents some restrictions such as the limited amount of bone that can be taken from the patient and donor site morbidity. Bone marrow mononuclear cells (BM-MNCs) comprise progenitor and stem cells with pro-angiogenic and pro-osteogenic properties. Allogenic cancellous bone graft is a natural and biodegradable osteoconductive and osteoinductive scaffold. Combination of these two components could mimic the advantages of autologous bone grafting while avoiding its main limitations. METHODS: Long-bone pseudoarthrosis was treated in seven patients with autologous BM-MNCs from iliac crest combined with frozen allogenic cancellous bone graft obtained from the tissue bank. RESULTS: All patients showed complete bone consolidation 5.3 ± 0.9 months (range, 2-9 months) after cell transplantation. Moreover, limb pain disappeared in all of them. The mean follow-up was 35.8 ± 4.6 months after transplantation (range, 24-51 months) without pseudoarthrosis recurrence or pain reappearing. CONCLUSIONS: Combination of autologous BM-MNCs and allogenic bone graft could constitute an easy, safe, inexpensive and efficacious attempt to treat long-bone pseudoarthrosis and non-union by reproducing the beneficial properties of autologous bone grafting while restricting its disadvantages.