Molecular characterization of alpha-thalassemia in the Mexican population.

Background: alpha-Thalassemia (alpha-Thal) has been poorly characterized at the molecular level in Mexico.

Methods: 106 consecutive individuals identified in Laboratorios Clínicos de Puebla, with either hypochromia (MCH < 24 pg) and/or microcytosis (MCV < 75 fl in women or < 80 fl in man), without iron deficiency, with or without anemia were investigated in this study, along a 16 month-period. alpha and beta-Thal were looked for, the former were characterized at the molecular level.

Instrument- and protocol-dependent variation in the enumeration of CD34+ cells by flow cytometry.

Background: The information regarding the minimum number of CD34+ cells that are necessary to reconstitute hematopoiesis in patients undergoing peripheral blood progenitor cell transplantation is quite controversial. Some of the differences in these figures might be due to the selection of antibodies, staining protocols, and acquisition strategies for the flow cytometric enumeration of these cells.

Study Design And Methods: Twenty-seven human umbilical cord blood samples and 33 leukapheresis products were consecutively collected for this study.

Cell-penetrating anti-native DNA antibodies trigger apoptosis through both the neglect and programmed pathways.

It has been previously shown that certain antibodies to double stranded-DNA are capable to transgress the cell membrane, translocate to the cell nucleus and react with their antigens. When so doing, they signal the penetrated cells to undergo apoptosis. In this study we dissected the two main-streams of apoptotic triggering and found that the neglect, mitochondrial pathway, is definitely involved, but activation of caspases 2 and 8, classically known to be associated to the membrane pathway, also occurs in a small proportion of cells.

Report on the second Latin American consensus conference for flow cytometric immunophenotyping of hematological malignancies.

On May 3 and 4, 2005, the Second Latin American Consensus Conference for the Immunophenotyping of Hematological Malignancies took place in Queretaro, México, with representatives from 10 countries of the region and two external consultants. This document summarizes the major conclusions for which consensus were achieved. Major differences regarding the recommendations from the first conference, which took place 9 years ago, concern the medical indications and the antibody panels for immunophenotyping.

HFE-codon 63/282 (H63D/C282Y) gene variants in Mexican Mestizos are not risk factors for leukemia.

Background: In some Caucasian populations it has been found that the C282Y hemochromatosis (HFE) gene mutation is a risk factor for the development of leukemia and other malignancies.

Methods: In a group of 50 Mexican mestizo patients and 153 normal controls, the HFE gene mutations H63D and C282Y were studied by means of ARMS-PCR.

Results: In the group of patients with leukemia we found a heterozygote for the C282Y mutation, seven heterozygotes for the H63D mutation, a double heterozygote for the H63D / C282Y mutation and 41 normal homozygotes.

Parvovirus B19 infection in medical students during a hospital outbreak.

From March to May 2002, a parvovirus B19 (B19) outbreak was identified at a general hospital that serves as a teaching facility for the Universidad Autónoma de San Luis Potosí, Mexico. Medical students attending the hospital presented with symptoms suggestive of B19 infection. Previous studies have suggested that apparent hospital-related B19 outbreaks may be a reflection of B19 infection in the community.

Long-term results of the immunosuppressive treatment of patients with severe acquired aplastic anemia: a single institution study.

In México, only few patients can afford adequate treatment for aplastic anemia. In a single institution 61 individuals with severe aplastic anemia (SAA) were identified; of these, 33 were followed for at least 3 months, 26 could be treated with immunosuppression (IS), 20 with antithymocyte globulin and cyclosporin A (ATG + CyA) and 6 with CyA, whereas 7 individuals were given only anabolic androgens. In the patients treated with IS a complete remission was achieved in 12 and a partial remission in 6, the overall response rate being 69%.

Successful allogeneic stem cell transplantation with nonmyeloablative conditioning in patients with relapsed Hodgkin's disease following autologous stem cell transplantation.

Use of myeloablative preparative therapy and allogeneic stem cell transplantation (alloSCT) as salvage therapy for adult patients with relapsed hematologic malignancies after autologous stem cell transplantation (autoSCT) is generally unsuccessful due to very high treatment-related mortality rates. We report here the outcome of HLA-matched related donor alloSCT following nonmyeloablative preparative therapy in two patients with Hodgkin's disease, relapsed after autologous stem cell graft. Times from autoSCT to alloSCT were 9 and 11 months, respectively.

Antibody penetration into living cells: pathogenic, preventive and immuno-therapeutic implications.

The dogmatic and at one time prevalent concept that intact antibody molecules were not able to enter into viable cells has now been modified due to the availability of a large amount of experimental findings and clinical observations that indicate otherwise. Penetration of mature autoantibodies into living cells might participate in the pathogenesis of diverse autoimmune diseases, through inducing apoptosis of healthy tissues and cells, but also by contributing to the breakdown of self-tolerance through presentation of self-antigens to the immune system. Conversely, the penetration of naturally occurring autoantibodies into immature lymphoid cells might have a physiological role in the edition of the immune repertoire in healthy individuals.

Novel facts about an old marker: the LE cell.

For more than fifty years, lupus erythematosus (LE) cells were believed to result from in vitro opsonization of bare nuclei by serum antinuclear antibodies and their ultimate phagocytosis by neutrophils. Twenty years ago, we described that certain antinuclear antibodies could enter into viable cells, and later on, it was proved that penetration of anti-DNA antibodies into cells results in protracted active cell death. Recent findings indicate that the material engulfed by LE cells are apoptotic blebs as residuals of cells dying after penetration of anti-DNA antibodies.

Features of the engraftment of allogeneic hematopoietic stem cells using reduced-intensity conditioning regimens.

The features of the engraftment in 26 patients allografted using reduced-intensity conditioning regimen (8 with chronic myelogenous leukemia, 6 with acute myelogenous leukemia, 9 with acute lymphoblastic leukemia, 1 with hybrid acute leukemia, 1 with myelodysplasia and 1 with thalassemia major) were analyzed. Patients received a median of 10 x 10(8)/Kg mononuclear cells (range 1.6 to 22.

Waldenström's macroglobulinemia is infrequent in Mexican Mestizos: experience of a hematological diseases referral center.

Along a 17-year period 7,373 patients were prospectively studied in a private practice Health facility; of these 11 were patients with Waldenström's macroglobulinemia; calculations from these data and previous publications show that this lymphoid malignancy represents in Mexico 0.18% of all hematologic malignancies, a figure 11 times lower than that described from caucasians. The median age was 65 years (range 31 to 84); there were 6 males and 5 females.

Are there "Attenuated" Forms of Evans Syndrome?

Indirect evidence of hemolysis has been described in patients with autoimmune thrombocytopenic purpura. In order to collect more data, another method to assess red blood cell destruction in these patients was employed: measurement of free haptoglobin levels. In 17 individuals with autoimmune thrombocytopenic purpura the levels of free haptoglobins were assessed after carefully ruling out microangiopathic hemolysis, systemic lupus erythematosus or overt Evans syndrome.

'LE cells' result from phagocytosis of apoptotic bodies induced by antinuclear antibodies.

Lupus erythematosus (LE) cells are believed to represent phagocytosis by granulocytes of cell nuclei whose DNA has been 'depolymerized' and opsonized by serum factors, most likely antinuclear antibodies and C3b. Since it is known that certain antinuclear antibodies are capable of inducing apoptosis after intracellular penetration; and that the resulting apoptotic bodies can be ingested by non-professional phagocytes, we decided to investigate the possibility that LE cells could result from the phagocytosis of apoptotic bodies induced by antinuclear antibodies. We demonstrate herein, through different methodological approaches, that the ingested material within LE cells corresponds to apoptotic bodies, and that the LE cell phenomenon can be reproduced, in the absence of other serum factors, by penetrating murine monoclonal anti DNA antibodies.

Chronic lymphocytic leukemia is infrequent in Mexican mestizos.

Chronic lymphocytic leukemia (CLL) is the most frequent leukemia in adults living in Western countries, and accounts for approximately 30% of adult leukemias. In a 15-year period in a single institution, we identified 19 patients with CLL in a group of 211 adults with leukemia (9% of adult leukemias). Of these 19 CLL patients, 8 had a Caucasian phenotype, 4 were born outside the country, and only 11 were Mexican mestizos.

Penetration of anti-DNA antibodies into immature live cells.

Several data suggest that immature lymphoid cells are more prone to penetration and therefore are affected more by antibodies than their mature counterparts. In this study, we examined the penetration of monoclonal anti-DNA antibodies in several models of immature cells. Results confirm that most anti-DNA antibodies penetrate larger proportions of immature cells than normal adult cells.

[Abnormal hemoglobins and thalassemias in Mexico].

The distribution of abnormal hemoglobins in Mexico is derived from surveys and from the study of patients with hemolytic anemia. In aboriginal populations, more than 3,000 individuals have been studied: structural abnormal hemoglobins are virtually absent in Mexican Indians and the sporadic finding of hemoglobin S among them is due to admixture with Africans brought as slaves during the Spanish domination; two new variants of hemoglobin (Mexico and Chiapas) were found in aborigines. The surveys in hybrid groups in selected areas of the country show that in some West and East Coast communities there are different frequencies of Hb S heterozygous, and that a high prevalence of Hb S trait has been found in some communities similar to that in some African areas.

Tuberculosis-associated fatal hemophagocytic syndrome in a patient with lymphoma treated with fludarabine.

A patient with a stage IV high-grade non-Hodgkin's lymphoma who developed a fatal hemophagocytic syndrome is presented: When the patient had achieved complete remission and receiving fludarabine and chlorambucil/prednisone, she developed miliary tuberculosis, the CD4+ T-cell count then being 50/microL; the hemophagocytic syndrome ensuing at this point was fatal. Speculations about the predisposing factors that could have led to this complication are discussed focusing on the severe cellular immunosuppression which developed probably related to the use of fludafabine: it could be useful in the future to use anti-tuberculous prophylaxis in selected patients treated with this purine nucleoside analog.

Report on the first Latin American Consensus Conference for Flow Cytometric Immunophenotyping of Leukemia.

On October 16, 1996, the first Latin American Consensus Conference for the Immunophenotyping of Leukemia took place in Puebla, Mexico, with representatives from 10 countries of the region and two external consultants. This document summarizes the major conclusions for which scientific consensus was achieved. The purpose of disseminating these guidelines to the international community is based on the potential interest for other countries with similar social conditions and economical restrictions.

[1st Latin American consensus conference on immunologic typing of leukemias].

On October 16, 1996, the first Latinamerican Consensus Conference for the Immunophenotyping of Leukemia took place in the City of Puebla, Mexico, with representatives from ten countries of the region, and two external consultants. This document summarizes the major conclusions where scientific consensus was achieved.

Two cases of hypergranular acute lymphoblastic leukemia.

Two patients with hypergranular acute lymphoblastic leukemia are presented: they represent 1.4% of patients with acute lymphoblastic leukemia studied and treated in a single institution in the past 12 years. This frequency is substantially lower than that reported in Caucasian populations.

[Activated protein C resistance as a cause of thrombophilia].

The proportion of identifiable causes of familial thrombophilia has increased from 5-10% to 60-70% since the identification of activated protein C resistance (aPCR) in February 1993 by Dahlbäck et al. A mutation in the factor V gene (G-->A, 1691) leads to the so called Leiden mutation (R 506 Q) that produces a mutated factor V resistant to the catalytic action of activated protein C (aPC), yet normal in its procoagulant properties. This recently identified aPCR is in Nordic populations the most prevalent and well defined genetic defect associated with disease so far described.