Biomedical subjects

J Stoop

Publications and source records attributed to J Stoop.

4 recordsLinked to original sources

PubMed2005

Amplification and overexpression of the KIT gene is associated with progression in the seminoma subtype of testicular germ cell tumors of adolescents and adults.

We have previously identified amplification at 4q12 in testicular germ cell tumors of adolescents and adults centered around the KIT gene encoding a tyrosine kinase transmembrane receptor. Analysis of primary testicular germ cell tumors totaling 190 cases revealed 21% of the seminoma subtype with an increased copy number of KIT whereas this change was rarely found in the nonseminomas. In most cases, gain of KIT did not include the immediately flanking noncoding DNA or the flanking genes KDR and PDGFRA. Increased copy number of KIT was not found in the putative precursor lesion, carcinoma in situ (CIS), adjacent to tumor with this change. KIT overexpression was found independent of gain and KIT immunostaining was stronger in selected cases with gain of KIT compared to those without. Taken together with activating mutations of KIT in exon 17 identified in 13% of seminomas, this suggests that the KIT gene product plays a role in the progression of CIS towards seminoma, the further understanding of which may lead to novel less toxic therapeutic approaches.

Adolescent↗

PubMed2001

The crystallographic structure of the mannitol 2-dehydrogenase NADP+ binary complex from Agaricus bisporus.

Mannitol, an acyclic six-carbon polyol, is one of the most abundant sugar alcohols occurring in nature. In the button mushroom, Agaricus bisporus, it is synthesized from fructose by the enzyme mannitol 2-dehydrogenase (MtDH; EC ) using NADPH as a cofactor. Mannitol serves as the main storage carbon (up to 50% of the fruit body dry weight) and plays a critical role in growth, fruit body development, osmoregulation, and salt tolerance. Furthermore, mannitol dehydrogenases are being evaluated for commercial mannitol production as alternatives to the less efficient chemical reduction of fructose. Given the importance of mannitol metabolism and mannitol dehydrogenases, MtDH was cloned into the pET28 expression system and overexpressed in Escherichia coli. Kinetic and physicochemical properties of the recombinant enzyme are indistinguishable from the natural enzyme. The crystal structure of its binary complex with NADP was solved at 1.5-A resolution and refined to an R value of 19.3%. It shows MtDH to be a tetramer and a member of the short chain dehydrogenase/reductase family of enzymes. The catalytic residues forming the so-called catalytic triad can be assigned to Ser(149), Tyr(169), and Lys(173).

Agaricus↗

PubMed2001

Crystallization and preliminary crystallographic analysis of mannitol dehydrogenase (MtDH) from the common mushroom Agaricus bisporus.

Mannitol dehydrogenase (MtDH) is a key enzyme controlling the reductive synthesis of mannitol from fructose in the common mushroom Agaricus bisporus. A better understanding of the control of mannitol metabolism can be obtained by studying the structure of this enzyme. Here, the purification and crystallization of recombinant MtDH are reported. Crystals generally belonged to the space group C2, with unit-cell parameters a = 227, b = 125, c = 133 A, beta = 118 degrees, and diffracted to at least 1.8 A resolution, although a tantalum derivative belonged to the space group P2(1) and diffracted to the lower resolution of 2.9 A.

Agaricales↗

PubMed1990

Scenarios in the design process.

The Safety Science Group of Delft University of Technology has developed a method by which the input of safety in the design process is structured through the application of use-scenarios and hazard patterns. The approach is illustrated with case studies in the field of agricultural equipment (pneumatic pruning shears, power chain saws and power-take-off shafts). Use-scenarios and hazard patterns result from safety problem analyses and give structure to the problem space and assist in the explanation of accidents. Selection of solutions is facilitated by a matrix scheme which links technical design options and measures of a social and organisational nature into a set of coherent measures. In the evaluation of designs, the application of use-scenarios and hazard patterns is helpful as a predictor of residual risks. Incorporating safety in the design process is a dynamic decision-making process. The decisions involved and the role of the safety expert in this process are discussed. Application of the method to the design of tools and consumer products seems very promising, although several problems remain. Valid accident data for use in the method are scarce; the technique for the translation of safety requirements into design specifications is still not fully developed and the first projects are only now being carried through to the implementation stage.

Journal Article↗