Contributions to an integrated control programme of Hypsipyla grandella (Zeller) in Costa Rica

The shootborer Hypsipylagrandella (Zeller) (Lep., Pyralidae) is the main obstacle to the artificial regeneration of valuable meliaceous tree species such as mahogany ( Swietenia spp.) and Spanish cedar ( Cedrela spp.) in Latin America. On the other hand, the natural regeneration of these species is endangered due to depletion of the naturally existing resources and burning in colonization projects.This dissertation concerns the development of several fields of research, which when incorporated in a programme of integrated control may contribute to a solution of the Hypsipyla problem.Chapter 1 contains a general introduction on this insect pest and its host plants in Costa Rica. In addition, a review is provided of the economic importance of the pest in tropical forestry and of the previous and contemporary investigations on the possibilities of its control.The research carried out in the framework of the Inter-American Working Group on Hypsipyla at the tropical Research and Training Centre of the Inter-American Institute of Agricultural Sciences at Turrialba, Costa Rica, is dealt with in Chapter 2.These investigations refer to the natural resistance of Meliaceae, host selection, development of an artificial rearing technique for H . grandella and to a survey of parasites in Costa Rica which might be employed in a biological control of the shootborer.The main results are:a. Two exotic Meliaceae, African mahogany ( Khayaivorensis ) and the Australian cedar ( Toonaciliatavaraustralis ) were introduced and were found to be immune against attacks of the shootborer. Biological and chemical screening for the basis of resistance of the Australian cedar led to the location of two toxic components in the aqueous fraction of young leaves and shoots of this tree species. The toxicity of Toona can be translocated to Cedrelaodorata grafted on the Australian cedar.b. Experiments on the host selection of H . grandella point at the existence of a host selection mechanism in which the female adult orients itself towards the host by means of olfaction. Fourth instar larvae of the borer prefer native hosts to exotic species as food sources.c. An artificial rearing technique was developed for H . grandella . A diet (Vanderzant) used for rearing Heliothiszea appeared to be a suitable medium for mass rearing Hypsipyla . Although initially mating of adults could only be obtained in outdoor cages in Costa Rica, subsequent rearing in Wageningen, under completely artificial conditions, proved to be perfectly feasible. Larval and pupal periods of H . grandella reared on artificial and natural diets were determined, and compared. Female adults are generally larger than males and live longer. Artificially reared females still restrict oviposition to meliaceous host plants.d. A survey of biological control agents of -the shootborer resulted in the following new records of H . grandella parasites in Costa Rica: Trichogramma f asciatum , T . pretiosum , T . near pretiosum , T . semifumatum , Hypomicrogasterhypsipylae sp. n., Brachymeriaconica and Braconchontalensis ; an Agathis sp. has to be identified yet. In addition the nematode Hexamermisalbicans was found to parasitize larvae of the shootborer in Swieteniamacrophylla and Cedrela spp. The egg parasite Trichogrammasemifumatum could be reared easily on eggs of H . grandella

Tissue adhesives for meniscus tear repair:an overview of current advances and prospects for future clinical solutions

Contains fulltext : 171814.pdf (publisher's version ) (Open Access)Menisci are crucial structures in the knee joint as they play important functions in load transfer, maintaining joint stability and in homeostasis of articular cartilage. Unfortunately, ones of the most frequently occurring knee injuries are meniscal tears. Particularly tears in the avascular zone of the meniscus usually do not heal spontaneously and lead to pain, swelling and locking of the knee joint. Eventually, after a (partial) meniscectomy, they will lead to osteoarthritis. Current treatment modalities to repair tears and by that restore the integrity of the native meniscus still carry their drawbacks and a new robust solution is desired. A strong tissue adhesive could provide such a solution and could potentially improve on sutures, which are the current gold standard. Moreover, a glue could serve as a carrier for biological compounds known to enhance tissue healing. Only few tissue adhesives, e.g., Dermabond((R)) and fibrin glue, are already successfully used in clinical practice for other applications, but are not considered suitable for gluing meniscus tissue due to their sub-optimal mechanical properties or toxicity. There is a growing interest and research field focusing on the development of novel polymer-based tissue adhesives, but up to now, there is no material specially designed for the repair of meniscal tears. In this review, we discuss the current clinical gold standard treatment of meniscal tears and present an overview of new developments in this field. Moreover, we discuss the properties of different tissue adhesives for their potential use in meniscal tear repair. Finally, we formulate recommendations regarding the design criteria of material properties and adhesive strength for clinically applicable glues for meniscal tears

De nonvlinder (Lymantria monacha L) in 1984 en 1985; plaag, bestrijding en onderzoek.

In 1984 en 1985 werd de nonvlinder na 70 jaar massaal aangetroffen in vnl. grovedennenbos bij Budel en Luijksgestel. De opstand bij Budel werd afdoende bestreden met Dimilin. De niet behandelde opstand in Luijksgestel werd nagenoeg kaalgevreten door de nonvlinder. Gebleken is dat het noodzakelijk is het populatieverloop te volgen. Overwegingen die bij het besluit om bestrijding toe te passen van belang zijn, worden gegeven, evenals mogelijkheden van het gebruik van chemische en biologische bestrijdingsmiddele

Amphiphilic poly(ether ester amide) multiblock copolymers as biodegradable matrices for the controlled release of proteins

Amphiphilic poly(ether ester amide) (PEEA) multiblock copolymers were synthesized by polycondensation in the melt from hydrophilic poly(ethylene glycol) (PEG), 1,4-dihydroxybutane and short bisester-bisamide blocks. These amide blocks were prepared by reaction of 1,4-diaminobutane with dimethyl adipate in the melt. A range of multiblock copolymers were prepared, with PEG contents varying from 23-66 wt %. The intrinsic viscosity of the PEEA polymers varied from 0.58-0.78. Differential scanning calorimetry showed melting transitions for the PEG blocks and for the amide-ester blocks, suggesting a phase separated structure. Both the melting temperature and the crystallinity of the hard amide-ester segments decreased with increasing PEG content of the polymers. The equilibrium swelling ratio in phosphate buffered saline (PBS) increased with increasing amount of PEG in the polymers and varied from 1.7 to 3.7, whereas the polymer that contained 66 wt % PEG was soluble in PBS. During incubation of PEEA films in PBS, weight loss and a continuous decrease in the resulting inherent polymer viscosity was observed. The rate of degradation increased with increasing PEG content. The composition of the remaining matrices did not change during degradation. A preliminary investigation of the protein release characteristics of these PEEA copolymers showed that release of the model protein lysozyme was proportional to the square root of time. The release rate was found to increase with increasing degree of swelling of the polymers

POLY(TRIMETHYLENE CARBONATE)AND POLY(D,L-LACTIC ACID) MODIFY HUMAN DENDRITIC CELL RESPONSES TO STAPHYLOCOCCI BUT DO NOT AFFECT Th1 AND Th2 CELL DEVELOPMENT

Biomaterial-associated infections (BAIs) are frequent complications in the use of medical devices (biomaterials) correlated with considerable patient discomfort and high treatment costs. The presence of a biomaterial in the host causes derangement of local immune responses increasing susceptibility to infection. Dendritic cells (DCs) have an important role in directing the nature of immune responses by activating and controlling CD4+ T helper (Th) cell responses. To assess the immunomodulatory effect of the combined presence of biomaterials and Staphylococcus aureus (S. aureus) or Staphylococcus epidermidis (S. epidermidis), DC-mediated T cell proliferation and Th1/Th2 cell development were measured using an in vitro human cell system. Poly(trimethylene carbonate) (PTMC) and poly(D,L-lactic acid) (PDLLA) modified the production of the DC pro-inflammatory cytokines TNF-α, IL-6 and IL-23 in response to S. aureus and S. epidermidis. However, this modified cytokine production did not cause differences in Th1/Th2 cell polarisation, showing a Th1 cell predominance. In the absence of staphylococci, neither of the biomaterials induced DC-mediated T cell proliferation or Th1/Th2 cell polarisation. Moreover, either in the absence or presence of the biomaterials, S. aureus was a more potent inducer of DC cytokine secretion, T cell proliferation and Th1 cell development than S. epidermidis. In conclusion, although PTMC and PDLLA modulated DC cytokine responses to staphylococci, this did not alter the resulting Th cell development. This result suggested that, in this human cell model, Th1/Th2 cell responses were mainly determined by the species of bacteria and that PTMC or PDLLA did not detectably influence these responses

Aliphatic isocyanurates and polyisocyanurate networks

The production, processing, and application of aliphatic isocyanate (NCO)-based thermosets such as polyurethane coatings and adhesives are generally limited by the surprisingly high viscosity of tri-functionality and higherfunctionality isocyanurates. These compounds are essential crosslinking additives for network formation. However, the mechanism by which these high viscosities are caused is not yet understood. In this work, model aliphatic isocyanurates were synthesized and isolated in high purity (>99%), and their viscosities were accurately determined. It was shown that the presence of the NCO group has a strong influence on the viscosity of the system. From density functional theory calculations, a novel and significant bimolecular binding potential of À8.7 kJ/mol was identified between NCO groups and isocyanurate rings, confirming the important role of the NCO group. This NCO-to-ring interaction was proposed to be the root cause for the high viscosities observed for NCO-functional isocyanurate systems. Molecular dynamics simulations carried out to further confirm this influence also suggest that the NCO-toring interaction causes a significant additional contribution to viscosity. Finally, model functional isocyanurates were further reacted into densely crosslinked polyisocyanurate networks which showed interesting material properties

Ectopic bone formation in cell-seeded poly(ethylene oxide)/poly(butylene terephthalate) copolymer scaffolds of varying porosity

Scaffolds from poly(ethylene oxide) and poly(butylene terephthalate), PEOT/PBT, with a PEO molecular weight of 1,000 and a PEOT content of 70 weight% (1000PEOT70PBT30) were prepared by leaching salt particles (425–500 μm). Scaffolds of 73.5, 80.6 and 85.0% porosity were treated with a CO2 gas plasma and seeded with rat bone marrow stromal cells (BMSCs). After in vitro culture for 7 days (d) in an osteogenic medium the scaffolds were subcutaneously implanted for 4 weeks in nude mice. Poly(d, l-lactide) (PDLLA) and biphasic calcium phosphate (BCP) scaffolds were included as references. After 4 weeks (wks) all scaffolds showed ectopic formation of bone and bone marrow. For the scaffolds of different porosities, no significant differences were observed in the relative amounts of bone (7–9%) and bone marrow (6–11%) formed, even though micro computed tomography (μ-CT) data showed considerable differences in accessible pore volume and surface area. 1000PEOT70PBT30 scaffolds with a porosity of 85% could not maintain their original shape in vivo. Surprisingly, 1000PEOT70PBT30 scaffolds with a porosity of 73.5% showed cartilage formation. This cartilage formation is most likely due to poorly accessible pores in the scaffolds, as was observed in histological sections. μ-CT data showed a considerably smaller accessible pore volume (as a fraction of the total volume) than in 1000PEOT70PBT30 scaffolds of 80.6 and 85.0% porosity. BMSC seeded PDLLA (83.5% porosity) and BCP scaffolds (29% porosity) always showed considerably more bone and bone marrow formation (bone marrow formation is approximately 40%) and less fibrous tissue ingrowth than the 1000PEOT70PBT30 scaffolds. The scaffold material itself can be of great influence. In more hydrophobic and rigid scaffolds like the PDLLA or BCP scaffolds, the accessibility of the pore structure is more likely to be preserved under the prevailing physiological conditions than in the case of hydrophilic 1000PEOT70PBT30 scaffolds. Scaffolds prepared from other PEOT/PBT polymer compositions, might prove to be more suited