Weight change and quality of life in a community-based population

*Objectives:* This study investigates the longitudinal association between 5-year weight change and quality of life (QoL) in Dutch men and women.

*Design:* A prospective cohort study (1998, 2000, 2003) in a population based sample. Subjects: 2,414 men and women from the Maastricht region of the Netherlands.

*Measurements:* QoL outcomes were measured by the RAND-36 (eight subscales and two overall composite scores, physical and mental health (PCS and MCS)). Weight was measured on a scale. Weight change was calculated as change in weight between 1998 and 2003. In addition, 5-year weight change was also categorized in three groups: weight losers, weight maintainers, and weight gainers. All analyses were stratified for gender.

*Results:* A total of 598 men (50%) and 646 women (54%) maintained their weight, 177 men (15%) and 163 women (14%) lost more than 2.5 kg, and 410 men (35%) and 379 women (32%) gained more than 2.5 kg. Associations between 5-year weight change and QoL were found for MCS ([beta] = 0.13, 95% CI: 0.02|0.24) in women, and PCS ([beta] = -0.09, 95% CI: -0.17|-0.00; [beta] = -0.10, 95% CI: -0.19|-0.01) in men and women respectively. Moreover, associations between weight change and QoL were most pronounced for women of normal weight and obese men. Furthermore, in both genders, weight gainers showed a greater reduction on all physical components of QoL compared with weight maintainers. However, after 5-years weight gainers and weight losers did not significantly differ from weight maintainers in the mean change of MCS and PCS.

*Conclusion:* Weight gain was inversely associated with the physical domains of QoL in women and obese men. Conversely, in women, weight gain was positively associated with the mental domains of QoL. No differences between weight losers and weight gainers were found in mean change of QoL compared with weight maintainers

Artificial selection for timing of dispersal in predatory mites yields lines that differ in prey exploitation strategies

Dispersal is the main determinant of the dynamics and persistence of predator–prey metapopulations. When defining dispersal as a predator exploitation strategy, theory predicts the existence of a continuum of strategies: from some dispersal throughout the predator–prey interaction (the Milker strategy) to dispersal only after the prey had been exterminated (the Killer strategy). These dispersal strategies relate to differences in prey exploitation at the population level, with more dispersal leading to longer predator–prey interaction times and higher cumulative numbers of dispersing predators. In the predatory mite Phytoseiulus persimilis, empirical studies have shown genetic variation for prey exploitation as well as for the timing of aerial dispersal in the presence of prey. Here, we test whether artificial selection for lines that differ in timing of dispersal also results in these lines differing in prey exploitation. Six rounds of selection for early or late dispersal resulted in predator lines displaying earlier or later dispersal. Moreover, it resulted—at the population level—in predicted differences in the local predator–prey interaction time and in the cumulative numbers of dispersers in a population dynamics experiment. We pose that timing of dispersal is a heritable trait that can be selected in P. persimilis, which results in lines that show quantitative differences in local predator–prey dynamics. This opens ways to experimentally investigate the evolution of alternative prey exploitation strategies and to select for predator strains with prey exploitation strategies resulting in better biological control

Pain, Course and Treatment of Osteo arthritis in Primary Care

Osteoarthritis (OA) is the most frequent joint disease causing pain and functional disability in middle-aged and elderly persons. As OA is not curable, treatment is mainly symptom driven and consist of pharmacological and non-pharmacological therapies. Treatments are focused on alleviating pain, maintenance of activities in daily life, enhancing quality of life and postponing the moment of total joint replacement. The aim of this thesis is to improve our understanding of the reported severity of pain due to OA. In the first part of this thesis, the results of a clinical trial on the effectiveness of pain medication in treating knee pain due to clinical OA in general practice are presented. In addition, the results of a systematic review on the heterogeneity of studies assessing the effectiveness of pain medication in OA are presented. In the second part of this thesis, longitudinal pain trajectories of patients with hip OA are described. Furthermore, data are reported on the specific features of the knee assessed with MRI and its associations with both weight-bearing and non-weight-bearing pain.pain alleviatio

Characterization of a defective form of tomato spotted wilt virus

The work described in this thesis was aimed at the elucidation of the nature of a defective form of TSWV which does not form complete particles during infection.Properties of TSWV and the existence of a defective form of this virus are described in Chapter 1. A survey of the literature on three different types of defective viruses with properties significant for the understanding of the defect in TSWV is given also in this chapter. The purposes of the study are presented at the end of this chapter.In view of a defect in the genome of TSWV experiments were performed to determine the exact number of RNA segments in normal TSWV particles and the coding function of each individual RNA segment (Chapter 2). Electrophoresis of TSWV RNA on denaturing agarose gels revealed three segments with mol. wts. of 2.7, 1.7 and 1.1 x 10 6, to which will be referred as RNA 1, 2 and 3.TSWV RNA acted as messenger in a cell-free system of wheat germ and in a mRNA-dependent rabbit reticulocyte lysate, indicating that it is of a positive strand. Analysis of the in vitro translation products by gel electrophoresis revealed that two major polypeptides were synthesized in both systems. One could be indentified by immunoprecipitation as the nucleocapsid protein; the identity of the other polypeptide, having a mol. wt. of 60 000, is unknown.The positive strandness of TSWV RNA could be confirmed by other experiments. TSWV RNA labelled with 125I did not hybridize with polyribosomal RNA from infected leaves and transcriptase activity could not be detected in purified preparations of TSWV or in nucleocapsid extracts from infected leaves.In vitro translation of the RNA of TSWV fractionated on sucrose gradients, and analysis of the translation products revealed that the nucleocapsid protein and a protein with a mol. wt. of 60 000 is encoded for by RNA 3. The coding functions of the two other RNA segments could not be determined.The viral proteins present in plants infected with defective isolates were analysed by serological means (Chapter 3). Antibodies were raised against the nucleocapsid protein and against a fraction containing the membrane proteins of TSWV Sap from leaves infected with isolates either of the normal or the defective form were tested in ELISA. Antibodies directed against the nucleocapsid protein reacted with sap from leaves infected with isolates of both forms. Antibodies directed against the membrane proteins reacted only with sap from leaves infected with normal isolates and not at all with sap from leaves infected with defective isolates. These results indicate that the defective form does not direct the synthesis of membrane proteins and consists solely of nucleocapsids.Chapter 4 and 5 describe the analysis of the RNAs which are synthesized in leaves upon infection with either the normal or defective form of TSWV Polyribosomes were isolated from infected plants at different times of infection. They were allowed to complete nascent polypeptide chains in an in vitro translation system and the synthesized polypeptides were analysed by polyacrylamide gel electrophoresis. Synthesis of the nucleocapsid protein in the course of infection with isolates of both forms could be detected. However, synthesis of the other viral structural proteins or proteins other than the polypeptides synthesized under direction of polyribosomes from healthy plants, could not be observed (Chapter 4).The RNAs synthesized upon infection were also analysed by hybridization (Chapter 5). The three individual TSWV RNA segments were labelled with 32P and hybridized with dsRNA isolated from plants infected with isolates either of the normal or defective form. RNA 1 and RNA 3 hybridized to the same extent with dsRNA from plants infected with isolates of both forms. RNA 2 hybridized to a significant lower value with dsRNA from plants infected with the defective isolate. This result indicates that in plants infected with the defective isolate the genetic information of RNA 1 and RNA 3 of normal TSWV particles is present, but the information of RNA 2 is only partly present. Since the defective form does not direct the synthesis of membrane proteins, RNA 2 contains possibly the information for the membrane proteins.Chapter 6 describes experiments on the nature of the electron dense amorphous masses, by which the defective form is defined electron microscopically. An infectious nucleoprotein-rich fraction was purified from plants infected with several defective isolates. Analysis by ELISA and polyacrylamide gel electrophoresis revealed the presence of nucleocapsid protein of TSWV in this fraction. NO other viral structural proteins were found. Electron microscopic examination of this fraction demonstrated structures resembling the electron dense amorphous masses. As this fraction was infectious it is concluded that the characteristic amorphous masses are composed of nucleocapsids. Analysis by gel electrophoresis of RNA extracted from the fraction revealed that the three defective isolates of TSWV studied have an RNA 1 and RNA 3 with the same mobility as those of normal TSWV particles. RNA 2 was much smaller, indicating that RNA 2 of the normal form has lost a fragment. The same conclusion was also obtained in experiments in which the viral RNA segments were hybridized with dsRNA (Chapter 5).The results of this study are discussed in Chapter 7. The nature of the defect in TSWV giving rise to the defective form is defined and the significance of the results in view of the coding functions of the three RNA segments of TSWV is discussed. Also, the defective form of TSWV is compared with the defective forms of other viruses and the possible role of the viral envelope in the transmission of TSWV by thrips is discussed

Three-Dimensional Transmission Electron Microscopy: A Novel Imaging and Characterization Technique with Nanometer Scale Resolution for Materials Science

Three-dimensional transmission electron microscopy (3D-TEM), effectuated by multiple imaging of a sample combined with image analysis, offers a new approach in materials science to obtain 3D information of complex solid materials. Here we report first-of-its-kind results that have been obtained with zeolite materials. Virtual cross-sections and volume rendering of the 3D reconstruction of a metal/zeolite crystal (Ag/NaY) give unequivocal information on the location of the silver particles (10-40 nm in diameter). Virtual cross-sections of the 3D reconstruction of an acid-leached mordenite show the three-dimensional mesoporous channel system (3-20 nm in diameter) with a clarity and definition not seen before