RESUMEN

We evaluated the outcome of 227 patients with acute myeloid leukemia during three decades (period 1 - 1980’s, N = 89; period 2 - 1990’s, N = 73; period 3 - 2000’s, N = 65) at a single institution. Major differences between the three groups included a higher median age, rates of multilineage dysplasia and co-morbidities, and a lower rate of clinical manifestations of advanced leukemia in recent years. The proportion of patients who received induction remission chemotherapy was 66, 75, and 85 percent for periods 1, 2, and 3, respectively (P = 0.04). The median survival was 40, 77, and 112 days, and the 5-year overall survival was 7, 13, and 22 percent, respectively (P = 0.01). The median disease-free survival was 266, 278, and 386 days (P = 0.049). Survival expectation for patients with acute myeloid leukemia has substantially improved during this 30-year period, due to a combination of lower tumor burden and a more efficient use of chemotherapy and supportive care.

Asunto(s)

RESUMEN

We evaluated the outcome of 227 patients with acute myeloid leukemia during three decades (period 1 - 1980's, N = 89; period 2 - 1990's, N = 73; period 3 - 2000's, N = 65) at a single institution. Major differences between the three groups included a higher median age, rates of multilineage dysplasia and co-morbidities, and a lower rate of clinical manifestations of advanced leukemia in recent years. The proportion of patients who received induction remission chemotherapy was 66, 75, and 85% for periods 1, 2, and 3, respectively (P = 0.04). The median survival was 40, 77, and 112 days, and the 5-year overall survival was 7, 13, and 22%, respectively (P = 0.01). The median disease-free survival was 266, 278, and 386 days (P = 0.049). Survival expectation for patients with acute myeloid leukemia has substantially improved during this 30-year period, due to a combination of lower tumor burden and a more efficient use of chemotherapy and supportive care.

Asunto(s)

RESUMEN

Telomere shortening provides a molecular basis for the Hayflick limit. Recent data suggest that telomere shortening also influence mitotic rate. We propose a stochastic growth model of this phenomena, assuming that cell division in each time interval is a random process which probability decreases linearly with telomere shortening. Computer simulations of the proposed stochastic telomere-regulated model provides good approximation of the qualitative growth of cultured human mesenchymal stem cells.

Asunto(s)

RESUMEN

The dividing line between leukemia and lymphoma is usually not very clear. We put forward the hypotheses that simple concepts of set theory are valuable tool in order to verify the consistency of the available definitions of leukemia and lymphoma. Set theory is the branch of mathematics that leads with collections or sets of objects and has many applications. A set can be described by listing the properties that its members must have in order to belong to the set. We developed a group of organizational properties regarding cellular origin (designated [O] for origin), progression [P] and differentiation [D] of the malignant hematopoietic cells. We selected definitions of leukemia and lymphoma from medical literature and analyzed these definitions according to properties [O], [P] and [D]. Fourteen definitions were selected for analysis (seven of leukemia and seven of lymphoma). For each definition, we listed the properties that define leukemia and lymphoma as a set of hematological malignancies. The main property that characterizes the set of lymphomas was the lymphoid differentiation. This property was present in all seven definitions of lymphoma and should be regarded a necessary condition to define this neoplasia. Definitions of leukemia were not uniform and no common property was present in all of them. Altogether, these results demonstrate that current definitions do not permit a precise classification of hematological malignancy as leukemia or lymphoma. The definitions of leukemia are not uniform and this term could be modified.

Asunto(s)

RESUMEN

Magnetization reversal was studied in square arrays of square Co/CoO dots with lateral size varying between 200 and 900 nm. While reference nonpatterned Co/CoO films show the typical shift and increased width of the hysteresis loop due to exchange bias, the patterned samples reveal a pronounced size dependence. In particular, an anomaly appears in the upper branch of the magnetization cycle and becomes stronger as the dot size decreases. This anomaly, which is absent at room temperature in the patterned samples, can be understood in terms of a competition between magnetostatic interdot interaction and exchange anisotropy during the magnetic switching process.

RESUMEN

The role of bone marrow biopsy in the staging of Hodgkin's disease is undergoing reevaluation. We have studied the relationship of clinical factors to the presence of bone marrow involvement in 130 previously untreated patients with Hodgkin's disease. The presence of fever, spleen enlargement, anemia, leukopenia, poor performance status and poor histologic subgroups were positively correlated with the presence of bone marrow involvement in the univariate analysis. In the multivariate analysis, only fever, spleen involvement, leukopenia and poor histologic subgroups were significant. The predictive value of the absence of fever in regard to the absence of bone marrow involvement was 98%. The likelihood of bone marrow involvement in the absence of all four significant factors was only 0.05%. Patients without these clinical factors should probably not be submitted to a bone marrow biopsy as part of the staging procedures performed in Hodgkin's disease.

Asunto(s)