Treatment time of image-guided radiotherapy with a Halcyon 2.0 system.

INTRODUCTION: The treatment fraction time is a key indicator of the external beam radiotherapy process. The Halcyon system was designed to improve the clinical workflow, according to the manufacturer (Varian Medical Systems). Few works studied the actual delivery efficiency of the Halcyon system. This work analyzed the treatment time on a Halcyon 2.0 unit for a variety of sites along a period of 9 months. MATERIALS AND METHODS: Treatment time included patient setup, image acquisition, image-guided online couch correction, and radiation delivery time. Data were extracted from the ARIA oncology information system and were studied as a function of the treatment site, the delivery modality, and the time from the first day of treatments with the Halcyon 2.0 system in our institution. RESULTS: A total of 8599 fractions were delivered during the analyzed period (69.5% from VMAT plans, and 30.5% from IMRT plans). The number of fractions by site ranged from 30 for anal canal to 1933 for prostate. Five sites (prostate, lung, pelvis with prostate, breast, and gynecological sites) accounted for the 84% of the fractions. After a 2-week adaptation period of the staff, the daily mean treatment time was reduced to less than 12 min. The mean treatment time of all the fractions amounted to 10.5 ± 3.8 min. CONCLUSIONS: The Halcyon 2.0 allowed delivering online image-guided radiation therapy in all fractions with total treatment time consistently below the 12-min standard time slot, for most of the analyzed treatment sites.

Spatial Learning Promotes Adult Neurogenesis in Specific Regions of the Zebrafish Pallium.

Adult neurogenesis could be considered as a homeostatic mechanism that accompanies the continuous growth of teleost fish. As an alternative but not excluding hypothesis, adult neurogenesis would provide a form of plasticity necessary to adapt the brain to environmental challenges. The zebrafish pallium is a brain structure involved in the processing of various cognitive functions and exhibits extended neurogenic niches throughout the periventricular zone. The involvement of neuronal addition as a learning-related plastic mechanism has not been explored in this model, yet. In this work, we trained adult zebrafish in a spatial behavioral paradigm and evaluated the neurogenic dynamics in different pallial niches. We found that adult zebrafish improved their performance in a cue-guided rhomboid maze throughout five daily sessions, being the fish able to relearn the task after a rule change. This cognitive activity increased cell proliferation exclusively in two pallial regions: the caudal lateral pallium (cLP) and the rostral medial pallium (rMP). To assessed whether learning impinges on pallial adult neurogenesis, mitotic cells were labeled by BrdU administration, and then fish were trained at different periods of adult-born neuron maturation. Our results indicate that adult-born neurons are being produced on demand in rMP and cLP during the learning process, but with distinct critical periods among these regions. Next, we evaluated the time course of adult neurogenesis by pulse and chase experiments. We found that labeled cells decreased between 4 and 32 dpl in both learning-sensitive regions, whereas a fraction of them continues proliferating over time. By modeling the population dynamics of neural stem cells (NSC), we propose that learning increases adult neurogenesis by two mechanisms: driving a chained proliferation of labeled NSC and rescuing newborn neurons from death. Our findings highlight adult neurogenesis as a conserved source of brain plasticity and shed light on a rostro-caudal specialization of pallial neurogenic niches in adult zebrafish.

Esterilización tubaria transvaginal: Experiencia en el Hospital Universitario de Caracas

Objetivo: Evaluar las ventajas de la técnica de esterilización tubaria por vía vaginal en pacientes que acudieron al servicio de Ginecología del Hospital Universitario de Caracas y Ambulatorio del IVSS Patrocino Peñuela Ruíz, de enero a noviembre de 2014. Métodos: Investigación tipo ensayo clínico multicéntrico, en 49 mujeres no puérperas en edad fértil que solicitaron la esterilización quirúrgica. Se realizó la técnica de colpotomía posterior para localizar las trompas y realizar la esterilización. Resultados: La edad promedio fue de 32,5 años. El 80 % tenía de 1 a 3 partos. El 12,2 % tenía una cesárea previa y dos el 16, 3 %. El tiempo promedio de intervención fue de 22,8 minutos y de pérdida sanguínea de 32,5 cm³, sin necesidad de hemoderivados. Las complicaciones intraoperatorias se presentaron en 6 % de los casos, ameritando laparotomía 2 casos. Se pudo demostrar que las adherencias retrasan el tiempo quirúrgico. Según la escala visual análoga (EVA), 53,1 % de las pacientes a las seis horas no tenía dolor y a las 12 horas había disminuido notoriamente en el 85,7 %. Conclusión: La esterilización quirúrgica por colpotomía es beneficiosa porque el tiempo quirúrgico es corto, el sangrado escaso, el dolor leve y las complicaciones bajas.

Objective: To evaluate the advantages of tubal ligation by colpotomy incision in patients who assisted to the Gynecology Unit of University Hospital of Caracas and Patrocino Peñuela Ruíz Hospital form January to November 2014. Methods: Multicentric clinical assay, performed in 49 patients of reproductive age who demanded tubal ligation. Posterior colpotomy was performed to access the Fallopian tubes. Results: Mean age was 32,5 years. Eighty percent had 1 to 3 vaginal deliveries. One previous C section was reported in 12 %, and 2 in 16, 3 %. Mean surgery time was 22,8 minutes, and the mean blood loss 32,5 cc; blood transfusión was not required. Intraoperatory complications were present in 6 % of cases, 2 of them required laparotomy. The presence of adherences was related to longer surgical time. According to the Visual Analogue Scale (VAS), 53,1 % of the patients had no pain 6 hours after the surgery, and pain decreased significantly in 85. 7 % of the patients 12 hours after the procedure. Conclusion: Tubal ligation by colpotomy is highly recommended due to the short surgical time and low rate of complications, blood loss and pain.