Chemical defoliation of seed corn production fields accelerates seed maturation and desiccation and expedites seed harvest. Early seed harvest is important to minimize the risk of frost damage while in the field. This newly adopted seed production practice also allows seed companies to plan harvest and manage dryer space more efficiently. However, premature defoliation may interfere with the migration of oil bodies within embryo cells during desiccation and affect seed germination and vigor. The objective of this study was to investigate the effect of chemical defoliation on the migration patterns of oil bodies within embryo cells during desiccation. Chemically defoliated and non-defoliated plants from five commercial hybrid seed corn fields were sampled in 2014 and 2015. Whole ears with husks were harvested before and after defoliant application at 600 g H2O kg−1 fresh weight (fw), and weekly thereafter until seed reached approximately 300–350 g H2O kg−1 fw. Ten embryos extracted from center-row seeds were fixed to stop metabolic processes, then sliced, processed, and photographed using scanning transmission electron microscopy. The oil bodies within embryo cells followed normal migration patterns according to seed moisture content, regardless of defoliation treatment. Seed germination and vigor were verified and were not significantly affected by defoliation. Chemical defoliation is a viable production practice to accelerate seed corn desiccation and to manage harvest and seed dryer availability more efficiently without negatively affecting seed germination and vigor.

INTRODUCTION Primary central nervous system (CNS) sarcomas are rare mesenchymal non-meningothelial tumors accounting for less than 0.2% of intracranial lesions. Diagnosis and management are challenging due to the current lack of substantive clinical, histological and molecular data. METHODS We retrospectively identified all patients with diagnosis of primary CNS sarcoma at the Hospital Fundación Pediatrico la Misericordia (HOMI) in Bogota, Colombia. We collected patient demographics, disease characteristics, and outcomes for analysis. RESULTS Between 2008 and 2020, twenty-four consecutive patients were diagnosed at the HOMI representing 6% of all CNS tumors diagnosed over the same time period. The median age at presentation was 9.48 years (range:1.6–13.4). The median time of symptoms prior to diagnosis was 2 weeks (0.1–24). The most common presentation was headache (21/24- 89%) and vomiting (19/24- 79%). The frontal lobe was involved in 63% of patients (15/24) and only one patient presented with a cerebellar lesion. Histologically, these tumors were characterized by a pleomorphic spindle cell architecture and high mitotic activity. All samples lacked immunoreactivity to GFAP, CD34, EMA, and S100 and all samples had strong nuclear immunopositivity for TLE-1; BCL-2 was reactive in eighteen cases. Gross total resection was attained in fifteen patients, most patients received focal radiation therapy and ICE chemotherapy. Progression-free survival at 12 and 24 months was 57% and 31% respectively. Overall survival was 77% at 12 months and 39% at 24 months. Thirteen patients relapsed, 11 presented with local failures, and 2 with intracranial recurrences outside of the radiation field. CONCLUSION Our study identifies TLE-1 as a diagnostic marker of primary CNS sarcoma, a highly malignant supratentorial tumor of childhood. Further molecular studies are urgently needed to elucidate the biology of this disease and the unusually high incidence observed in the Colombian pediatric population.

Molecular classification of medulloblastomas helps in improving risk-stratification. However, application in routine practice remains a challenge in low and middle-income countries. In Colombia, children often have delayed and uncomplete diagnosis. We underwent a retrospective analysis of 49 cases of medulloblastoma treated between 2009 and 2017 in a reference pediatric hospital in Bogotá, Colombia. This manuscript reports the use of a immunohistochemical plus PCR panel to distinguish SHH, WNT, and non-SHH/WNT tumors and details their clinical and pathological features. We analyzed Beta-catenin, p75NTR, PIGU, OTX2, YAP1 and P53 by immunohistochemistry and performed PCR for C-myc and N-myc amplification. We found a high percentage of SHH tumors and a high prevalence of desmoplastic-nodular tumors in our series. The male: female ratio was different from reported in other latitudes. We believed it would be important to complement these results by new generation sequencing and the gold standard in the medulloblastoma diagnosis, the methylation analysis. However, the panel we propose is useful to predict the molecular group. This is the first medulloblastoma case series in Colombia.

Conventional laboratory equipment used in seed germination research provides only constant and alternating temperature. The temperature of the soil in the seed bed is hardly ever constant or alternating in the same manner, but fluctuates constantly. In order to simulate the fluctuation of soil temperature that occurs in the field, a soil temperature simulator (STS) was designed, built, and evaluated. Plastic crispers containing soil in which seed are to be planted can be partially submerged in a rectangular tank into which water can be placed to a depth of 10 cm. Temperature of the water can be adjusted by heating and refrigeration systems under the control of a variable input programmer system. Maximum capabilities of the STS are: (i) maximum temperature drop 4 °C/h, (ii) maximum temperature rise 7.5 °C/h, and (iii) maximum temperature gradient within the unit 1.0 °C. The STS is capable of simulating fluctuations in soil temperature within a range of 4 to 40 °C and is particularly suited for the study of seed imbibitional chilling injury.

Manifestaciones radiológicas de leucemia linfoide aguda en niños