Biomedical subjects

G J B van Ommen

Publications and source records attributed to G J B van Ommen.

4 recordsLinked to original sources

PubMed2005

Common pathological mechanisms in mouse models for muscular dystrophies.

Duchenne/Becker and limb-girdle muscular dystrophies share clinical symptoms like muscle weakness and wasting but differ in clinical presentation and severity. To get a closer view on the differentiating molecular events responsible for the muscular dystrophies, we have carried out a comparative gene expression profiling of hindlimb muscles of the following mouse models: dystrophin-deficient (mdx, mdx(3cv)), sarcoglycan-deficient (Sgca null, Sgcb null, Sgcg null, Sgcd null), dysferlin-deficient (Dysf null, SJL(Dysf)), sarcospan-deficient (Sspn null), and wild-type (C57Bl/6, C57Bl/10) mice. The expression profiles clearly discriminated between severely affected (dystrophinopathies and sarcoglycanopathies) and mildly or nonaffected models (dysferlinopathies, sarcospan-deficiency, wild-type). Dystrophin-deficient and sarcoglycan-deficient profiles were remarkably similar, sharing inflammatory and structural remodeling processes. These processes were also ongoing in dysferlin-deficient animals, albeit at lower levels, in agreement with the later age of onset of this muscular dystrophy. The inflammatory proteins Spp1 and S100a9 were up-regulated in all models, including sarcospan-deficient mice, which points, for the first time, at a subtle phenotype for Sspn null mice. In conclusion, we identified biomarker genes for which expression correlates with the severity of the disease, which can be used for monitoring disease progression. This comparative study is an integrating step toward the development of an expression profiling-based diagnostic approach for muscular dystrophies in humans.

Animals↗

PubMed2003

Fluorescent labelling of cRNA for microarray applications.

Microarrays of oligonucleotide expression libraries can be hybridised with either cDNA, generated from mRNA during reverse transcription, or cRNA, generated in an Eberwine mRNA amplification procedure. While methods for fluorescent labelling of cDNA have been thoroughly investigated, methods for cRNA labelling have not. To this purpose, we developed an aminoallyl-UTP (aa-UTP) driven cRNA labelling protocol and compared it in expression profiling studies using spotted 7.5 K 65mer murine oligonucleotide arrays with labelling via direct incorporation of Cy-UTPs. The presence of dimethylsulfoxide during coupling of aa-modified cRNA with N-hydroxysuccinimide-modified, fluorescent Cy dyes greatly enhanced the labelling efficiency, as analysed by spectrophotometry and fluorescent hybridisation signals. Indirect labelling using aa-UTP resulted in 2- to 3-fold higher degrees of labelling and fluorescent signals than labelling by direct incorporation of Cy-UTP. By variation of the aa-UTP:UTP ratio, a clear optimal degree of labelling was found (1 dye per 20-25 nt). Incorporation of more label increased Cy3 signal but lowered Cy5 fluorescence. This effect is probably due to quenching, which is more prominent for Cy5 than for Cy3. In conclusion, the currently developed method is an efficient, robust and inexpensive technique for fluorescent labelling of cRNA and allows sensitive detection of gene expression profiles on oligonucleotide microarrays.

Carbocyanines↗

PubMed2002

FcgammaRI (CD64) contributes substantially to severity of arthritis, hypersensitivity responses, and protection from bacterial infection.

The high-affinity receptor for IgG, FcgammaRI, shares its capacity to bind IgG2a immune complexes (IgG2a-IC) with the low-affinity receptor FcgammaRIII and complement factors, hampering the definition of its biological role. Moreover, in vivo, FcgammaRI is occupied by monomeric IgG2a, reducing its accessibility to newly formed IgG2a-IC. By using a variety of FcgammaR(-/-) mice, we demonstrate that in the absence of FcgammaRI, the IgG2a-IC-induced cellular processes of phagocytosis, cytokine release, cellular cytotoxicity, and antigen presentation are impaired. FcgammaRI(-/-) mice showed impaired hypersensitivity responses, strongly reduced cartilage destruction in an arthritis model, and impaired protection from a bacterial infection. We conclude that FcgammaRI contributes substantially to a variety of IgG2a-IC-dependent immune functions and immunopathological responses.

Animals↗

PubMed2002

The Human Genome Project and the future of diagnostics, treatment and prevention.

The Human Genome Project, the mapping of our 30,000-50,000 genes and the sequencing of all of our DNA, will have major impact on biomedical research and the whole of therapeutic and preventive health care. The tracing of genetic diseases to their molecular causes is rapidly expanding diagnostic and preventive options. The increased insights into molecular pathways, gained from high-throughput 'functional genomics', using DNA-chip and protein-chip approaches and specially designed animal model systems, will open great prospects for pharmacological and genetic therapies. Powerful bioinformatics and biostatistics will further improve our pattern recognition and accelerate progress. A rapidly expanding area of high expectations is that of 'pharmacogenomics': the design of more effective drugs with lower toxicity through tailoring of drug treatment to individual, genetically determined differences in drug metabolism. Not only will this decrease the cost of health care through reduction of adverse drug reactions, but a better stratification of populations will also provide more statistical power farther upstream in drug trials. However, the optimal benefits from the current explosion of 'data mining' will only be realized when the basic data are made and kept publicly accessible, while at the same time safeguarding the protection of intellectual property arising from downstream inventions. This is one of the goals of HUGO, the international Human Genome Organization, established 13 years ago to assist coordination of data acquisition and exchange and societal implementation of the genome project. Additional points of attention in this historic endeavour are the prevention of stigmatization and discrimination and the safeguarding of a worldwide balance in the contribution by--and benefits to--different populations, while respecting the diversity in cultures and traditions.

Ethics, Medical↗