Biomedical subjects

Melchor Alvarez-Mon

Publications and source records attributed to Melchor Alvarez-Mon.

26 records · Page 2Linked to original sources

PubMed2002

Human cord blood CD34+Pax-5+ B-cell progenitors: single-cell analyses of their gene expression profiles.

Circulating CD34(+) cells are used in reparative medicine as a stem cell source, but they contain cells already committed to different lineages. Many think that B-cell progenitors (BCPs) are confined to bone marrow (BM) niches until they differentiate into B cells and that they do not circulate in blood. The prevailing convention is that BCP transit a CD34(+)CD19(-)10(+) early-B-->CD34(+)CD19(+)CD10(+) B-cell progenitor (pro-B)-->CD34(-)CD19(+)CD10(+) B-cell precursor (pre-B) differentiation pathway within BM. However, populations of CD34(+)CD10(+) and CD34(+)CD19(+) cells circulate in adult peripheral blood and neonatal umbilical cord blood (CB) that are operationally taken as BCPs on the basis of their phenotypes, although they have not been submitted to a systematic characterization of their gene expression profiles. Here, conventional CD34(+)CD19(+)CD10(+) and novel CD34(+)CD19(+)CD10(-) BCP populations are characterized in CB by single-cell sorting and multiplex analyses of gene expression patterns. Circulating BCP are Pax-5(+) cells that span the early-B, pro-B, and pre-B developmental stages, defined by the profiles of rearranged V-D-J(H), CD79, VpreB, recombination activating gene (RAG), and terminal deoxynucleotidyl transferase (TdT) expression. Contrary to the expectation, circulating CD34(+)CD19(-)CD10(+) cells are essentially devoid of Pax-5(+) BCP. Interestingly, the novel CD34(+)CD19(+)CD10(-) BCP appears to be the normal counterpart of circulating preleukemic BCPs that undergo chromosomal translocations in utero months or years before their promotion into infant acute lymphoblastic B-cell leukemia after secondary postnatal mutations. The results underscore the power of single-cell analyses to characterize the gene expression profiles in a minor population of rare cells, which has broad implications in biomedicine.

Antigens, CD19↗

PubMed2002

Apoptotic rate: a new indicator for the quantification of the incidence of apoptosis in cell cultures.

BACKGROUND: Late apoptotic cells divide into apoptotic bodies and are missed by current detection methods. This results in an artificially low apoptotic index (AI). METHODS: This study proposes a flow cytometry-based ratiometric method that uses an internal reference standard of microbeads combined with fluorescein-annexin V binding and 7-aminoactinomycin D to enumerate viable, necrotic, and early and late apoptotic cells within specific subsets of a heterogeneous culture. RESULTS: In the absence of cell growth, the number of apoptotic cells that undergo fragmentation into apoptotic bodies in culture can also be determined accurately by this method. This information can then be used to obtain the apoptotic rate (AR), a new indicator of apoptosis that calculates the proportion of cells that have undergone apoptosis with respect to the total number of seeded cells. The main limitation of the method is that the AR is only suitable for the study of apoptosis in noncycling cells. CONCLUSIONS: This study reveals the superiority of the proposed method over the widely used Nicoletti method and current annexin-V binding methods. The AI did not reflect the true incidence of lymphocyte apoptosis, neither in response to lectins or phorbol esters, nor to serum deprivation. AR was more sensitive than AI, detecting apoptosis at lower concentrations of cell death inducers in all the subsets studied.

Apoptosis↗

PubMed2002

Synthesis and antiproliferative activity of a new compound containing an alpha-methylene-gamma-lactone group.

The biological activity of compound 9 obtained by introducing an alpha-methylene-gamma-butyrolactone group into 3-(4-hydroxyphenyl)propionic acid, 1, was studied for possible effects on HL-60 cells, murine splenocytes, and human peripheral mononuclear cells (PBMC). 9 induced apoptosis in the HL-60 cell line and has a clear capacity to inhibit proliferation induced in murine splenocytes and PBMC by different mitogenic agents with no apparent toxic side effects. 9 was synthesized from 1, and its structure and stereochemistry were elucidated by spectroscopic methods.

4-Butyrolactone↗

PubMed2002

Relationship between response to interferon-alpha and function of peripheral blood mononuclear cells in chronic hepatitis C patients.

The factors responsible for the low response of chronic hepatitis C patients to interferon-a treatment are not fully understood, although it is known that interferon requires an efficient host immune response to achieve viral clearance. This study was designed to test the hypothesis that hepatitis C virus infection is associated with functional impairment of peripheral blood mononuclear cells, which influence the response to interferon. The proliferative and apoptotic responses of peripheral blood mononuclear cells and purified T cells stimulated with polyclonal mitogenic signals were assessed in 35 chronic hepatitis C patients and 30 healthy controls. Patients were divided into responders and nonresponders according to their sustained response to a course of alpha-interferon-a (3 MU three times weekly for 12 months). The proliferative response to polyclonal mitogens (PHA, TPA) was significantly decreased in nonresponders compared to responders and controls. The defective response was partially normalized by the exogenous addition of interleukin-2 or interleukin-4, and cannot be ascribed to increased apoptosis. Interestingly, the proliferative response of enriched T cells to the same signals was normal. In conclusion, the clinical response to interferon-a defines two different patterns of proliferation by mononuclear cells in chronic hepatitis C patients. This suggests that an alteration of the immune system in these patients may underlie their inadequate response to antiviral therapy.

Adult↗

PubMed2002

AM3 (Inmunoferón) as an adjuvant to hepatitis B vaccination in hemodialysis patients.

BACKGROUND: Patients with end-stage renal disease (ESRD) undergoing hemodialysis have severe alterations in cell-mediated immunity (CMI) that increases their risk of contracting chronic hepatitis B virus (HBV) infection and decreases their protective responses to HBV vaccine. In an effort to improve the humoral response to an accelerated HBV vaccine protocol in these patients, the ability of an immunomodulator, AM3, to improve seroconversion was investigated. METHODS: A total of 269 patients were enrolled in a multicenter trial. All patients received a DNA recombinant vaccine (40 microg HBsAg/dose/day) on days 0, 10, 21, and 90. AM3 or placebo (3 g/day) was given orally for 30 consecutive days beginning 15 days prior to the first vaccine dose. Anti-HBsAg titers were measured on days 120 and 270 after the beginning of the trial. RESULTS: After one month, 207 patients could be evaluated and 132 patients after six months. The placebo and AM3-treated groups had comparable seroconversion and protective response rates one month after the final vaccine dose. The AM3 treatment group, but not the placebo group, maintained these protective titers up to six months after the final vaccine dose. At this time, the percentage of high responders (anti-HBsAg>100 IU/L) and mean anti-HBsAg titers in the AM3 group was significantly higher than in the placebo group. CONCLUSIONS: AM3 is a safe and easily tolerated oral agent that potentiates long-term serological immunity to hepatitis B in hemodialysis patients after vaccination.

Adjuvants, Immunologic↗

PubMed2002

Inflammatory bowel disease (Crohn's disease) in a Spanish patient with pars plana exudates: report of a new case and review of the literature.

Several ocular manifestations have been found in Crohn's disease patients, most often affecting the anterior segment. This paper presents the case of a young woman with pars plana exudates in whom Crohn's disease was later diagnosed. To the authors' knowledge, this is only the second report of Crohn's disease and concomitant pars plana exudates.

Adult↗

PubMedDate not supplied

Quantitation of apoptosis induction by etoposide or hydroxyurea in mouse interleukin 3-dependent lymphoma cells.

BACKGROUND: The apoptosis induction by etoposide or hydroxyurea in mouse interleukin 3-dependent lymphoma cells (DA-1) was studied. Treatments with 1.25 mM hydroxyurea and 100 microM etoposide for 17 hours were considered appropriate concentrations for such studies. MATERIALS AND METHODS: The viability of the cells was studied by propidium iodide exclusion. The presence of apoptotic bodies was observed, and DNA fragmentation of apoptotic cells was asessed by the observation of ladder patterns in agarose electrophoresis gels and an increase in the proportion of cells with subdiploid DNA content in cytometric studies. RESULTS: Alterations of membrane properties, DNA degradation and chromatin condensation highlighted a possible apoptotic process induced by these two antitumor agents. CONCLUSION: These studies have established conditions for examining apoptotic processes in interleukin 3-dependent lymphoma cells. This is of great interest for deeper analysis of the mechanisms involved in the apoptosis of these cells after interleukin 3 depletion or treatment with cytotoxic antitumor compounds.

Animals↗

PubMedDate not supplied

Involvement of Bax, Bcl-2 and caspase 3 in hydroxyurea- or etoposide-induced apoptosis of mouse interleukin-3-dependent lymphoma cells.

BACKGROUND: The apoptosis action induced by hydroxyurea or etoposide in interleukin 3-dependent lymphoma cells (DA-1) was studied. MATERIALS AND METHODS: The conditions to study apoptosis of these cells were 17 hours of cell treatment with concentrations of 1.25 mM hydroxyurea or 100 microM etoposide using flow cytometry, fluorometry and immunoblots techniques. RESULTS: Time-dependent reductions of cell viability after these treatments were observed. Caspase 3 activity was highly activated in both cases. Chemical treatments or interleukin 3 withdrawal rendered level changes in Bax and Bcl-2 expression. CONCLUSION: These results support the implication of these factors in DA-1 cell apoptosis induced by these chemical treatments or interleukin 3 depletion.

Animals↗