Modelling and simulation of brinicle formation.

Below the Arctic sea ice, under the right conditions, a flux of icy brine flows down into the sea. The icy brine has a much lower fusion point and is denser than normal seawater. As a result, it sinks while freezing everything around it, forming an ice channel called a brinicle (also known as ice stalactite). In this paper, we develop a mathematical model for this phenomenon, assuming cylindrical symmetry. The fluid is considered to be viscous and quasi-stationary. The heat and salt transport are weakly coupled to the fluid motion and are modelled with the corresponding conservation equations, accounting for diffusive and convective effects. Finite-element discretization is employed to solve the coupled system of partial differential equations. We find that the model can capture the general behaviour of the physical system and generate brinicle-like structures while also recovering dendrite composition, which is a physically expected feature aligned with previous experimental results. This represents, to our knowledge, the first complete model proposed that captures the global structure of the physical phenomenon even though it has some discrepancies, such as brine accumulation.

Hemofilia B o enfermedad de Christmas / Hemophilia B or Christmas disease

La hemofilia B o enfermedad de Christmas se diferenció por primera vez de la hemofilia A en 1947. Su forma clásica consiste en un trastorno hereditario de la coagulación causado por mutaciones en el gen F9, que codifica para el factor IX de la coagulación. Su herencia está ligada al cromosoma X; las mujeres son portadoras, pero se manifiesta clínicamente en hombres, aunque se han descrito casos de mujeres portadoras sintomáticas. El factor IX activado es una proteína dependiente de vitamina K, sintetizada en el hígado, que forma parte del complejo tenasa, cuya función es formar la mayor cantidad de trombina en el nuevo modelo de la coagulación basado en células. De acuerdo a la actividad del factor IX, su deficiencia se puede clasificar en leve (5% a 40%), moderada (1% a 5%), o severa (<1%). Su diagnóstico se realiza con la presencia de un TPT alargado que corrige con plasma normal y con la determinación del nivel funcional del factor IX, y se confirma con el estudio molecular que demuestra la mutación en el gen F9. Su diagnóstico diferencial incluye otras patologías como la hemofilia A. El tratamiento con factor IX recombinante es el más utilizado en la actualidad, pero se vienen desarrollando nuevas terapias con virus adeno-asociados recombinantes que prometen mejorar la calidad de vida para algunos pacientes afectados. La profilaxis juega un papel fundamental, en particular en los casos de enfermedad moderada y severa.

Hemophilia B or Christmas disease was first differentiated from hemophilia A in 1947. Its classic form consists of an inherited bleeding disorder caused by mutations in the F9 gene, which codes for coagulation factor IX. Its inheritance is linked to the X chromosome; women are carriers, but it manifests clinically in men, although cases of symptomatic women carriers have been described. Factor IX activates a vitamin K-dependent protein, synthesized in the liver, which is part of the tenase complex whose function is to form the largest amount of thrombin (factor IIa) in the new model of cell-based coagulation. According to factor IX activity, its deficiency can be classified as mild (5% to 40%), moderate (1% to 5%), and severe (<1%). The diagnosis is made when there is a prolonged TPT that corrects with normal plasma, and by assessing the functional level of factor IX. The diagnosis is confirmed by molecular analysis that demonstrates the F9 gene mutation. Its differential diagnosis includes disorders such as hemophilia A. Treatment with recombinant factor IX is widely used, but also new therapies are being developed with recombinant adeno-associated viruses that promise to improve the quality of life for some of these patients. Prophylaxis plays an important role in cases of moderate and severe disease

Eccrine cell tumor with natural evolution / Tumor de células ecrinas con evolución natural

Abstract Eccrine cell carcinoma constitutes a group of rare skin malignancies which are slow-growing but highly invasive. A case of multiple skin lesions with multifocal involvement, concluding with the histopathological documentation of this condition, is presented. (Acta Med Colomb 2019; 44. DOI:https://doi.org/10.36104/amc.2019.1203).

Resumen El carcinoma de células ecrinas constituye un grupo de neoplasias raras de la piel, de crecimiento lento pero altamente invasor. Se presenta un caso de lesiones cutáneas múltiples con compromiso multifocal que concluye con la documentación histopatológica de esta condición. (Acta Med Colomb 2019; 44. DOI:https://doi.org/10.36104/amc.2019.1203).

Renovascular hypertension secondary to congenital hypoplasia of renal arteries in middle adult patient. About a case / Hipertensión renovascular secundaria a hipoplasia congénita de arterias renales en un paciente adulto joven. A propósito de un caso

Abstract The tubular hypotrophy of the renal arteries constitutes a rare clinical entity, that is associated with the appearance of renovascular hypertension. Its diagnostic approach is complex and requires the availability of angiography to determine the features of the renal vessels. The following case exemplifies the diagnostic process of a patient with this special clinical situation.

Resumen La hipotrofia de aspecto tubular de las arterias renales constituye una rara entidad clínica asociada a la aparición de hipertensión renovascular. Su enfoque diagnóstico es complejo y exige la disponibilidad de angiografía para determinar las características propias del contorno de la vasculature renal. El caso clínico considerado en este artículo ejemplifica el proceso diagnóstico de un paciente con esta particular situación.

Menetrier's disease presenting as an acute protein-losing gastroenteropathy in a 27-year-old man with Gaucher disease.

OBJECTIVES: To describe a unique case of a young man with Gaucher disease who was diagnosed with Menetrier's disease. BACKGROUND: After an acute episode of severe gastritis, the patient developed hypoalbuminemia and protein-losing gastroenteropathy, and became unwell. STUDY: Endoscopy revealed an abnormal stomach, with rigid, thickened folds covered with viscous greyish exudates. Superficial biopsies revealed foveolar hyperplasia, acute and severe gastritis with massive inflammatory infiltrate of neutrophils in the lamina propria with pit abscess formation. Tissue cultures for Helicobacter pylori were negative. RESULTS: Snare deep particle biopsy revealed the typical features of Menetrier's disease. Enzyme replacement therapy for Gaucher disease was started. CONCLUSION: This case poses a dilemma because the patient improved spontaneously, and as such is dissimilar to other adults who develop Menetrier's disease because of an infection; it is hoped that he may also not be at risk of the potential malignancies that are correlated with adult Menetrier's disease. The value of enzyme treatment is considered.

Amyloidosis and gastric bleeding in a patient with Gaucher disease.

GOALS: To describe the clinical course of a patient with Gaucher disease who subsequently developed amyloidosis. BACKGROUND: We present a case of a splenectomized patient with Gaucher disease who developed portal hypertension secondary to an enlarged, cirrhotic-like liver, and recurrent life-threatening upper gastrointestinal bleeding. STUDY: Despite repeated diagnostic biopsies, amyloidosis was only ascertained after death. RESULTS: Albeit very rare, there are four other similar cases in the literature, but unlike these previous reports of concurrence of Gaucher disease and amyloidosis, in this patient the gastrointestinal symptoms were life-threatening but there was no evidence of gammopathy or renal disease. Also, this is the first patient who was treated with enzyme replacement therapy for 5 years prior to manifestation of amyloidosis. CONCLUSIONS: Coexistence of apparently unrelated diseases with Gaucher disease demands a greater awareness of abnormalities at the biochemical and/or molecular level to adequately manage patients with Gaucher disease, regardless of concurrent enzyme replacement therapy.