Biomedical subjects

Rafael Bornstein

Publications and source records attributed to Rafael Bornstein.

3 recordsLinked to original sources

PubMed2005

A modified cord blood collection method achieves sufficient cell levels for transplantation in most adult patients.

Umbilical cord blood transplantation (UCBT) has been used increasingly in both pediatric and adult patients. The total nucleated cell (NC) dose infused is the most critical factor in determining speed of engraftment and survival. Using standard collection techniques, the mean NC content of UCB units is about 10 x 10(8) and only 25% of these units reach the target cell dose of 2 x 10(7)/kg in UCBT patients weighing 50-70 kg. We have designed a modified placental/umbilical two-step collection method in which a standard blood fraction obtained by umbilical venipuncture is combined with a second fraction harvested after placental perfusion with 50 ml heparinized 0.9% saline. This second fraction contributed 32% volume and 15% NCs to the whole UCB unit (123.7 +/- 50.1 ml and 1.26 +/- 0.52 x 10(9) NC). The proportion of progenitor cells in both fractions was not significantly different, indicating that the hematopoietic potential of these larger units is 20% (range, 2%-100%) higher than UCB units collected by standard methods. In addition, the bacterial contamination rate associated with this novel collection method (2.78%) compares favorably. Since 1998 we have further enriched our units by processing only UCB units over 0.8 x 10(9) NCs, resulting in a 36% cell increment (1.46 +/- 0.52 x 10(9) NCs). Thus, 84% and 54% of the Madrid UCB Bank inventory would fulfill the target cell dose of 2 x 10(7)/kg in patients weighing 50 and 65 kg, respectively. This significant UCB banking improvement gives larger pediatric and adult patients a greater chance of finding adequate grafts in order to achieve better clinical outcomes after UCBT.

Adult↗

PubMed2004

A novel E2 box-GATA element modulates Cdc6 transcription during human cells polyploidization.

Cdc6 is a key regulator of the strict alternation of S and M phases during the mitotic cell cycle. In mammalian and plant cells that physiologically become polyploid, cdc6 is transcriptionally and post-translationally regulated. We have recently reported that Cdc6 levels are maintained in megakaryoblastic HEL cells, but severely downregulated by ectopic expression of transcriptional repressor Drosophila melanogaster escargot. Here, we show that cdc6 promoter activity is upregulated during megakaryocytic differentiation of HEL endoreplicating cells, and that Escargot interferes with such activation. Transactivation experiments showed that a 1.7 kb region located at 2800 upstream cdc6 transcription initiation site behaved as a potent enhancer in endoreplicating cells only. This activity was mainly dependent on a novel cis-regulatory element composed by an E2 box overlapping a GATA motif. Ectopic Escargot could bind this regulatory element in vitro and endogenous GATA-1 and E2A formed specific complexes in megakaryoblastic cells as well as in primary megakaryocytes. Chromatin Immunoprecipitation analysis revealed that both transcription factors were occupying the E2 box/GATA site in vivo. Altogether, these data suggest that cdc6 expression could be actively maintained during megakaryocytic differentiation through transcriptional mechanisms involving specific cis- and trans-regulatory elements.

5' Flanking Region↗

PubMedDate not supplied

Inconclusive presence of adenovirus sequences in human leukemias and lymphomas.

Adenoviruses are ubiquitous viruses related to human mild upper tract respiratory infections. Murine cells are semi-permissive to adenovirus replication, and persistent or abortive infections have been associated with tumorigenic potential. Given that only human lymphoid cells are semi-permissive and abortive infections have been described, we hypothesized that adenovirus could be related to the transformation of human haematopoietic cells. We studied 30 lymphomas, 46 leukemias, 10 reactive lymphadenopathies and 40 normal human spleens. The presence of adenovirus sequences and proteins were studied using PCR, southern-blot, slot-blot, in situ hybridization, immunohistochemistry, and western-blot techniques. By using nested PCR, adenovirus sequences were detectable in about 30% of lymphomas, but in less than 10% of leukemias, reactive lymphadenopathies and normal spleens. In no case were we able to demonstrate adenovirus products by in situ hybridization, immunohistochemistry or western-blot. These results indicate that adenovirus sequences are present in a significant number of human lymphomas, but that the number of positive cells is extremely low and no protein expression could be detected. Therefore, we are unable to conclude that persistent infections of human lymphoid cells by adenovirus is related to a higher risk of developing malignant lymphomas or leukemias.

Adenovirus E1A Proteins↗