Biomedical subjects

Daniela M Oliveira

Publications and source records attributed to Daniela M Oliveira.

3 recordsLinked to original sources

PubMed2006

Zinc phthalocyanine/magnetic fluid complex: a promising dual nanostructured system for cancer treatment.

In this study we evaluated the photophysical, photochemical properties of the zinc phthalocyanine/ magnetic fluid (ZnPC/MF) complex in liposomal medium. As a result of the present investigation we propose the liposome-encapsulated ZnPC/MF complex as a very promising nanostructured device for cancer treatment. The spectroscopy characterization and the in vitro dark toxicity of both ZnPC and ZnPC/MF complex in Hank's and in liposomal medium are reported. Our findings revealed that the spectroscopic properties of the ZnPC associated or not with MF presented little differences and are very close to what one expects from an ideal photosensitizer compound. Indeed, the ZnPC/MF complex in liposomal medium presented lower dark toxicity compared to the ZnPC/MF complex in Hank's, strongly supporting the use of the former for cancer treatment.

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PubMed2005

Differential mRNA processing in hematopoietic stem cells.

Hematopoietic stem cells (HSCs) maintain tissue homeostasis by rapidly responding to environmental changes. Although this function is well understood, the molecular mechanisms governing this characteristic are largely unknown. We used a sequenced-based strategy to explore the role of both transcriptional and post-transcriptional regulation in HSC biology. We characterized the gene expression differences between HSCs, both quiescent and proliferating, and their differentiated progeny. This analysis revealed a large fraction of sequence tags aligned to intronic sequences, which we showed were derived from unspliced transcripts. A comparison of the biological properties of the observed spliced versus unspliced transcripts in HSCs showed that the unspliced transcripts were enriched in genes involved in DNA binding and RNA processing. In addition, levels of unspliced message decreased in a transcript-specific fashion after HSC activation in vivo. This change in unspliced transcript level coordinated with increases in gene expression of splicing machinery components. Combined, these results suggest that post-transcriptional regulation is important in HSC activation in vivo.

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PubMed2003

Transient RNA interference in hematopoietic progenitors with functional consequences.

Short interfering (si) RNAs have now been shown to inhibit gene expression in several species, including mammals (Elbashir et al.: Nature 411:494-498, 2001; Fire et al.: Nature 391:806-811, 1998). RNA inhibition in primary cells such as stem cells would facilitate rapid gene discovery in a postgenome era. While retroviruses can deliver siRNA expression cassettes for stable expression (Barton and Medzhitov: Proc Natl Acad Sci USA 99:14943-14945, 2002; Paddison et al.: Proc Natl Acad Sci USA 99:1443-1448, 2002; Rubinson et al.: Nat Genet 33:401-406, 2003), an efficient method for direct transfer of siRNA to stem cells is still lacking. Here, we established electroporation to deliver siRNA to hematopoietic progenitors. On average, at least 80% of cells take up the RNA, and these display nearly 100% knockout of marker gene expression at both the RNA and protein level. Moreover, knockdown of the hematopoietic regulator, CD45, results in 3-fold more hematopoietic colonies in a progenitor assay. These results demonstrate that transient transfection of siRNA to primary cells can have substantial functional consequences. This technology may be applicable to a variety of primary cell types.

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