VIPSCAL: A combined vector ideal point model for preference data

In this paper, we propose a new model that combines the vector model and theideal point model of unfolding. An algorithm is developed, called VIPSCAL, thatminimizes the combined loss both for ordinal and interval transformations. As such,mixed representations including both vectors and ideal points can be obtained butthe algorithm also allows for the unmixed cases, giving either a complete idealpointanalysis or a complete vector analysis. On the basis of previous research,the mixed representations were expected to be nondegenerate. However, degeneratesolutions still occurred as the common belief that distant ideal points can be represented by vectors does not hold true. The occurrence of these distant ideal points was solved by adding certain length and orthogonality restrictions on the configuration. The restrictions can be used both for the mixed and unmixed cases in several ways such that a number of different models can be fitted by VIPSCAL.unfolding;ideal point model;vector model

Marine ecotoxicology: field and laboratory approaches

Preliminary results on the levels of organochlorine residues and mercury in the main compartments of the North Sea are described and the advantage of presenting data on three bases (wet weight, fat weight and water volume) is emphasized.Higher concentrations are by far found in the pelagic seabirds but no biomagnification can be detected at the first levels of the food chain (phytoplankton -zooplankton and fish). The results are discussed considering the relative importance. of the uptakes by food and directly from water.The modeling of the pollutants cycles in marine ecosystems requires notably the knowledge of the percentages of ingested pollutants assimilated, the concentration factors and the rates of excretion which all have to be determined in the laboratory.Some physiological adaptations to pollution are described which can change their kinetics of uptake and should be taken into account in the interpretation of the ecotoxicological data. Finally we discuss the fact that the liposolubility of all stable pollutants (organic and inorganic) would be related to their rate of uptake, suggesting that general laws describing the fate of pollutants in aquatic systems may exist

Kenya - Belgium project in marine sciences "Higher Institute for Marine Sciences" VLIR - KMFRI Project and CEC Project "Dynamics and Assessment of Kenyan Mangrove Ecosystems" No. TS2-0240-C (GDF): Progress Report November 1990 -June 1991

This report aims to give an overview of the results obtained over the last year in the frame of the VLIR project and the cooperating EEC project “Dynamics and Assessment of Kenyan Mangrove Ecosystems” (CEC Project nr TS 2-0240-C (GDF)). The mangrove ecosystem in Gazi has been intensively investigated. The researchers of the different subprojects are most often working in a coordinated way. A comprehensive set of data is now available and presented in this report. The Kenyan coastal area has especially been investigated for species distribution and coverage of marine algae and corals at different sites along the Kenyan coast. Most recently a pollution project, supported by UNEP, in collaboration with Kenyan Government chemist, was started. The first information on pollution sources and pollution loads have been obtained. The first data on monitoring of the pollution levels and their environmental impact, for the area around Mombasa are presented in this report. The aquaculture department is still small, nevertheless preliminary research is being done with success on fish culturing. The Oyster Commercial cultivation has started, is it on a very small scale. All information is now available to start real oyster farming. The Kenya-Belgium project was furthermore involved in the organization of a symposium: “Status and future of Large Marine Ecosystems”, to be held in between 2nd and 7th August 1992

Cytogenetic studies of PCB77 on brown trout (<i>Salmo trutta fario</i>) using the micronucleus test and the alkaline comet assay

Polychlorinated biphenyls (PCBs) are stable pollutants, which can be found in almost every compartment of terrestrial and aquatic ecosystems. They are very lipophilic and therefore have the potency of accumulating in the fat stores of animals. The mechanisms by which PCBs exert their adverse effects are still unclear. It is known that PCBs induce some important biotransformation enzymes, but their mutagenic properties are still controversial. The DNA breakage and clastogenic potency of a planar PCB77 (3,3',4,4'-tetrachlorobiphenyl) was determined in vivo in fish, using the single cell gel electrophoresis or comet assay and the micronucleus test, on erythrocytes of the brown trout exposed for 3, 9 and 14 days to initial PCB concentrations of 780 and 918 pg/ml, dissolved in the water, Blood was taken by a caudal puncture and the erythrocytes were either deposited in an agarose gel (0.6%) for the comet assay or smeared directly on slides for the micronucleus test. Five fish were studied per treatment and 50 and 2000 erythrocytes per concentration and per animal were analysed for the comet assay and the micronucleus test respectively. ethyl methanesulphonate (EMS) at a concentration of 25 mg/l water was used as a positive control. Although EMS induced a statistically significant increase of single strand breaks in the comet assay, in neither of the two tests used, were mutagenic effects due to PCB exposure observed

VIPSCAL: A combined vector ideal point model for preference data

In this paper, we propose a new model that combines the vector model and the ideal point model of unfolding. An algorithm is developed, called VIPSCAL, that minimizes the combined loss both for ordinal and interval transformations. As such, mixed representations including both vectors and ideal points can be obtained but the algorithm also allows for the unmixed cases, giving either a complete ideal pointanalysis or a complete vector analysis. On the basis of previous research, the mixed representations were expected to be nondegenerate. However, degenerate solutions still occurred as the common belief that distant ideal points can be represented by vectors does not hold true. The occurrence of these distant ideal points was solved by adding certain length and orthogonality restrictions on the configuration. The restrictions can be used both for the mixed and unmixed cases in several ways such that a number of different models can be fitted by VIPSCAL

Successful radiopeptide targeting of metastatic anaplastic meningioma: Case report

A patient with anaplastic meningioma and lung metastases resistant to conventional treatment underwent radiopeptide therapy with 177Lu- DOTA-octreotate in our institute. The treatment resulted in significant improvement in patient's quality of life and inhibition of tumor progression. This case may eventually help to establish the value of radiopeptide therapy in patients with this rare condition

The Role and Limitations of 18-Fluoro-2-deoxy-d-glucose Positron Emission Tomography (FDG-PET) Scan and Computerized Tomography (CT) in Restaging Patients with Hepatic Colorectal Metastases Following Neoadjuvant Chemotherapy: Comparison with Operative and Pathological Findings

BACKGROUND: Recent data confirmed the importance of 18-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) in the selection of patients with colorectal hepatic metastases for surgery. Neoadjuvant chemotherapy before hepatic resection in selected cases may improve outcome. The influence of chemotherapy on the sensitivity of FDG-PET and CT in detecting liver metastases is not known. METHODS: Patients were assigned to either neoadjuvant treatment or immediate hepatic resection according to resectability, risk of recurrence, extrahepatic disease, and patient preference. Two-thirds of them underwent FDG-PET/CT before chemotherapy; all underwent preoperative contrast-enhanced CT and FDG-PET/CT. Those without extensive extrahepatic disease underwent open exploration and resection of all the metastases according to original imaging findings. Operative and pathological findings were compared to imaging results. RESULTS: Twenty-seven patients (33 lesions) underwent immediate hepatic resection (group 1), and 48 patients (122 lesions) received preoperative neoadjuvant chemotherapy (group 2). Sensitivity of FDG-PET and CT in detecting colorectal (CR) metastases was significantly higher in group 1 than in group 2 (FDG-PET: 93.3 vs 49%, P < 0.0001; CT: 87.5 vs 65.3, P = 0.038). CT had a higher sensitivity than FDG-PET in detecting CR metastases following neoadjuvant therapy (65.3 vs 49%, P < 0.0001). Sensitivity of FDG-PET, but not of CT, was lower in group 2 patients whose chemotherapy included bevacizumab compared to patients who did not receive bevacizumab (39 vs 59%, P = 0.068). CONCLUSIONS: FDG-PET/CT sensitivity is lowered by neoadjuvant chemotherapy. CT is more sensitive than FDG-PET in detecting CR metastases following neoadjuvant therapy. Surgical decision-making requires information from multiple imaging modalities and pretreatment findings. Baseline FDG-PET and CT before neoadjuvant therapy are mandatory