Verhandelingen - Koninklijke Academie voor Geneeskunde van Belgie最新文献

Neuroblastoma (NB) is, next to acute lymphoblastic leukaemia, brain tumours and lymphoma the most frequent paediatric tumour (8-10%). Our research group aims to contribute to the unravelling of the genetic basis of NB. Insight into the genes and signalling pathways involved in tumour formation and development can represent an essential step towards the development of more efficient molecular targeted therapies. A first part of our research work was devoted to the analysis of genomic alterations in NB. By means of a new highly sensitive method for detecting gains and losses of chromosomal segments, we recognised three major prognostic relevant genomic subtypes of NB. In addition smaller subgroups with deviating genomic patterns were detected. In addition, this work yielded important information regarding delineation of critical regions of gain and loss in NB which should facilitate further selection of candidate oncogenes or tumour suppressor genes. A second important part of our work focussed on the gene expression profiling of NB precursor cells. We were able as the first to isolate these cells and determine their transcriptome, a finding of fundamental importance for future expression studies in NB. Another study focussed on the identification of MYCN transcriptional target genes. Gene expression analyses of model systems developed in our lab and of a large panel of cell lines and tumours allowed us to subtract a list of candidate genes which are now under further study. Finally, we initiated research towards the understanding of the role of methylation in NB oncogenesis. From this, we were able to create a list of potentially relevant methylated genes in NB. From the above it is clear that our team has made important contributions to the understanding of the complex biology and clinical behaviour of NB. Also, a broad technically innovative research platform has been developed which will allow us to dissect NB genetics with greater speed and accuracy.

In leukemias chromosomal aberrations, balanced translocations in particular, play a critical role in the oncogenic process. The characterization of these chromosomal alterations was crucial to the discovery of the genes implicated in leukemogenesis, as the chromosomal breakpoints indicated their genomic localization. In addition, these molecular defects may serve as targets for diagnostic essays and can have a major prognostic value. Finally, the characterization of the deregulated cellular pathways potentially identifies targets for therapeutic intervention. In this paper we summarize our efforts to expand the current knowledge of the diagnostic, prognostic or biological significance of selected chromosomal aberrations identified in M-FISH studies. First, we illustrated the power of M-FISH in dissecting complex chromosomal aberrations in myeloid neoplasms. MLL amplification was defined as a clinical entity characterized by adverse prognosis and within the multitude and variety of chromosomal rearrangements a pattern of a limited number of cytogenetic subclasses was discerned. In leukemias characterized by 11q23 amplification, we described the amplicon and confirmed MLL, in addition to DDX6, as a principal amplification target. Molecular characterization of a large series of unselected sporadic and recurrent 3q26 rearranged leukemias confirmed the decisive role of ectopic EVI1 expression in these malignancies. We contributed to an extensive analysis of the phenotypical and prognostic features of T-ALL characterized by HOX11L2 expression and identified HOX11L2 overexpression as one of the most frequent genetic defects in childhood T-ALL, associated with intermediate prognosis. Finally, we designed and validated diagnostic tools for the detection of the t(9;14) (p13;q34) resulting in PAX5 overexpression and convincingly associated the presence of this rearrangement to high-grade morphology and karyotype complexity. In conclusion, the series of investigations presented here clearly illustrate the benefits of M-FISH as molecular tool for the dissection and characterization of complex and cryptic rearrangements. The subsequent reports demonstrate the utility of molecular cytogenetics and expression analyses to the clinical management of patients diagnosed with hematological malignancies.

Cutaneous Malignant Melanoma (CMM) is the most malignant skin tumour in humans, the incidence of which is rising rapidly in most fair-skinned populations, without apparent decline in mortality. Both hereditary, constitutional and environmental factors play a role in its etiology. CMM arises from melanocytes in the epidermis, and proceeds through discrete steps of tumor-progression that consist histologically of the radial growth phase (RGP), vertical growth phase (VGP) and metastatic phase. The underlying molecular mechanisms that govern the transition between these growth phases are hardly known. The prognosis of patients with VGP melanoma depends on several clinical and histological parameters; the latter include thickness, mitotic activity, presence or absence of ulceration and regression, and pattern of lymphocytic host response. However, there is still need for new prognostic parameters. To obtain insight in the molecular mechanisms of tumor progression in CMM, and in search of new prognostic markers, we performed global gene-expression profiling using 44K oligonucleotide micro-arrays on a unique retrospective series of 83 frozen primary MM with VGP, 9 metastases and 23 benign nevi. Unsupervised analysis allowed us o identify clusters of melanoma patients with different outcome based on their gene expression profile only. Supervised analysis resulted in the identification of a genomic signature of 254 genes with prognostic significance. The large majority of the 254 enes was correlated with thickness, thereby stressing the importance of thickness in he prognosis of CMM. This signature was validated on a separate series of melanoma patients, and proved to have a predictive accuracy comparable to what can be obtained by tumour thickness and ulceration. On an immunohistochemical level, we identified 8 new markers that may help in the prognostication of melanoma patients; three of these markers, i.e. the mini-chromosome maintenance (mcm) proteins mcm3, 4 and 6, hat are involved in DNA-replication, had independent prognostic value. Additionally, upervised analysis showed similarities in gene expression profile between primary CMM and their metastases. In conclusion, our data provide new information regarding the molecules that are operative in the progression of CMM. CMM is notorious for its resistance to chemotherapy, and disseminated CMM is a uniformly fatal disease. As several of the progression-related genes, encode molecules that have been the target of established or xperimental cancer therapies, our results may hopefully contribute to the treatment of end-stage CMM-patients.

Chemokines have diverse roles in tumor biology. Monocyte chemotactic protein-(MCP-1)/CCL2 was the first chemokine described to elicit influx of monocyte/macrophages into tumors. Application of chemokines as anti-tumoral therapy to attract immunocompetent cells and to mediate the mounting of an efficient anti-tumoral response has been tested as a method to combat cancer for some years now. However, these chemokine-related therapy has not yet been approved for clinical application, although it has been tested succesfully in animal models for years now. A different kind of approach for chemokine anti-cancer therapy involves angiostatic chemokines. These chemokines inhibit pro-angiogenic tumoral factors, thereby limiting tumor growth and metastasis. Recently, we described a most potent new angiostatic chemokine, namely a variant of platelet factor 4, designated PF-4var/CXCL4L1. With regard to hematological tumors we described a new plasma chemokine, PARC/CCL18, that can be used to distinguish between pediatric patients with acute lymfoid leukemia or acute myeloid leukemia. Whether this elevated plasma concentration of PARC/CCL18 is the cause of the pathology or the consequence of a disturbed cytokine balance is not clear at the moment.

Cancer in a patient usually becomes manifest as a process of excessive cell growth in one or more organs which, if uncontrolled, will ultimately lead to death of the patient. The malignant clinical phenotype of cancer is the reflection of the altered cellular behaviour of individual cancer cells. Cumulative genetic alterations in pathways controlling cellular growth or survival, endow the latter cells with the capacity to grow independently of growth-regulating signals, to resist programmed cell death, to divide endlessly, and to interact differently with non-malignant cellular environment. The discovery of such recurrent genetic aberrations in haematological malignancies has led to new diagnostic tests, but also to a shift towards development of new rational, specific and effective targets for therapy. For instance, protein tyrosine kinases are pivotal switches for growth control, and small molecule inhibitors have profoundly reshaped therapeutic practice in in myeloproliferative disorders or acute lymphoblastic leukemias. New targets however also encompass the detrimental interactions of malignant cells with the normal environment, e.g. the immune system in the myelodysplastic syndromes. Finally, the paradigm of cancer as the result of cumulative genetic damage in normal cells also sheds new light on the vulnerability of congenital bone marrow failure syndromes to develop haematological malignancies. In this paper, we review our recent contributions to this cancer paradigm in malignant or premalignant haematological conditions.

The oxidative phosphorylation (OXPHOS) is a system that generates ATP by the transfer of electrons through the complexes of the respiratory chain. Mitochondria are very abundant in organs with high energy demand, including skeletal muscle, heart muscle and brain. The incidence of OXPOS defects is estimated at 1/10,000. Most frequently, a myopathy, encephalopathy or encephalomyopathy is seen. Mutations in the patients with OXPHOS defects can be located in the nuclear genome as well as in the mitochondrial genome which makes the search for the underlying gene defect very difficult. A diagnostic strategy is developed to make the search for the molecular defect easier. Besides the classical spectrophotometric analysis also Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE) is used. The latter can be combined with activity staining in the gel, or with immunoblotting of the complexes, or with SDS electrophoresis (2-dimensional electrophoresis). Also immunocytological and immunohistochemical analyses are used, especially for detection of heteroplasmy. Skeletal muscle and cultured skin fibroblasts are the favorite tissues used for the application of BN-PAGE and immunological techniques. BN-PAGE followed by activity staining in the gel is especially suited for detection of a deficiency of complex I or of complex V With the spectrophotometric method is it difficult to detect these deficiencies in cultured skin fibroblasts. With BN-PAGE the presence of subcomplexes of complex V can be visualized, which is an indication of a decreased intramitochondrial translation. The immunological stainings on the other hand are well suited for detection of heteroplasmy. The combined use of all these techniques allows the identification of the underlying gene defect in a significant number of patients.

The first successful gene therapy trials for the treatment of hereditary disorders underscore the potential of gene therapy to combat disease and alleviate human suffering. The development of gene therapy for hemophilia is not only a research priority in its own right but also serves as an ideal trailblazer for many different diseases. Significant progress has recently been made in the development of gene therapy for the treatment of hemophilia A and B. Long-term therapeutic levels of factor VIII and IX could be expressed following gene therapy in hemophilic mice, stably correcting the bleeding diathesis. These advances parallel the development of improved gene delivery systems. The induction of neutralizing antibodies (inhibitors) to the clotting factors could potentially preclude stable phenotypic correction. The risk of inhibitor formation varied, depending at least in part on the type of vector used and its in vivo tropism. We also demonstrated that the risk of immune responses to the vector particles, the clotting factors and/or transduced cells can be reduced by using vectors that only minimally interact with antigen presenting cells. In hemophilic mice, robust and stable clotting factor expression levels were achieved using adeno-associated viral vectors based on the newly disovered serotypes AAV8 and AAV9 which can efficient deliver the clotting factor genes into hepatocytes without triggering any inflammatory responses or adverse events. Pre-clinical studies in large animal models will be initiated to further validate these improved AAV vectors to ultimately justify a clinical trial in patients with severe hemophilia.

The Cochrane Collaboration is an international not-for-profit and independent organization, dedicated to making up-to-date, accurate information about the effects of healthcare readily available worldwide. It produces and disseminates systematic reviews of healthcare interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. The Cochrane Collaboration was founded in 1993 and named after the British epidemiologist, Archie Cochrane. A Cochrane review is a systematic review. Those who prepare the reviews are mostly healthcare professionals who volunteer to work in one of the many Cochrane review groups, with editorial teams overseeing the preparation and maintenance of the reviews, as well as application of the rigorous quality standards for which Cochrane Reviews have become known. Based upon a clearly defined clinical question all steps of a scientific paper with a rigourous design are inside. This will guide the review process including strategies for locating and selecting studies critically appraising their relevance and validity and for analyzing variation among their results. If there are sufficient studies of good quality a meta-analysis can be performed. The major product of the Collaboration is the Cochrane Database of Systematic Reviews which is published quarterly as part of the Cochrane Library. From 2008 there will be also a place for systematic reviews of diagnostic accuracy studies. The Belgian Centre of Evidence-Based medicine, CEBAM, plays an important role as Belgian Branch of the Dutch Cochrane Collaboration in maintaining and promoting Cochrane Systematic Reviews.

In the 1990's neuroanatomical models of language and semantic memory have been mainly based on functional neuroimaging studies of brain activity in healthy volunteers and correlational studies between structural lesions in patients and behavioral deficits. In this paper we present a novel approach where we test models that have been developed in healthy volunteers by means of functional imaging in patients in combination with behavioral studies. Study populations consist of patients with focal cortical stroke (n = 2), amnestic mild cognitive impairment (n = 14) and primary progressive aphasia (n = 18). The experiments provide converging evidence that 1. the integrity of the right mid- and anterior fusiform gyrus is required for full and detailed retrieval of knowledge of visual attributes of concrete entities 2. the left posterior superior temporal sulcus is critically involved in lexical-semantic retrieval 3. the anterior temporal pole to the left functions as an associative structure that links the representations of meaning that are distribured over the cortical brain surface. Our experiments also provide us with new insight into the degradation and re-organisation of the language system in cortical neurodegenerative disease.

In this lecture the science 'Pharmaceutical Technology' was briefly elucidated, but the main part was about the concept of 'Pharmaceutical Care' in the community pharmacy. Pharmaceutical Care aims at ensuring a safe, efficacious, and cost-effective pharmacotherapy. Thus the pharmacist tries--in collaboration with other healthcare professionals --to improve the clinical and humanistic outcomes of the therapy. Moreover, an efficacious and rational drug therapy is cost-saving, for the patient as well as for the health insurer. A pharmacist delivering Pharmaceutical Care not only dispenses medication, but also takes responsibility about the outcome of the drug therapy. Pharmaceutical Care in community pharmacies encompasses the following activities: Advice about prescribed drugs, to ensure that patients take their medication as correct, as safe and as compliant as possible. Advice about self-care: counselling about OTC-medication. Prevention of medication errors, for example drug interactions. Pay attention to prevention of diseases: for example stimulation of vaccination. Collaboration with physicians, especially general practitioners, both aiming at an optimal drug therapy for the patient Pharmaceutical Care in the hospital setting ('Clinical Pharmacy'): clinical pharmacists participate in drawing up, evaluating and following up the pharmacotherapy of every individual patient, in close collaboration with physicians, nurses and other healthcare professionals on the ward. In Belgium Pharmaceutical Care is in the making. Scientific research on this topic is carried out by the Pharmaceutical Care Unit of Ghent University. An overview of their ongoing research projects was given. Finally, the problems encountered with the implementation of Pharmaceutical Care were highlighted.