113 research outputs found
The impact of postharvest research
While research on the improvement of agricultural production has received considerable attention and funding, until recently postharvest activities have not attracted much attention from international research organizations. However, there is an emerging consensus on the critical role that postharvest systems can play in meeting the overall goals of food security, poverty alleviation and sustainable agriculture particularly in developing countries. This study provides preliminary evidence on the impact of postharvest research on these goals; furthermore the study argues that postharvest research at international agricultural research organizations is justified by its international public good nature.postharvest technology ,food security ,Poverty alleviation ,Research institutes ,postharvest technology ,
Strukturaufklärung und Reaktionsmonitoring katalytischer und photochromer Systeme mittels NMR
Die vorliegende Dissertation beschäftigt sich mit der Strukturaufklärung und der Reaktionsverfolgung verschiedener organischer Moleküle und Reaktionen. Hierbei werden klassische und neuartige Methoden der NMR-Spektroskopie entwickelt und eingesetzt.
Neben der klassischen - auf im Arbeitskreis Thiele etablierten Methoden beruhenden - Strukturaufklärung eines Triazols wurden für die Untersuchungen von drei Reaktionstypen Modellsysteme betrachtet: Zum einen die übergangsmetallkatalysierte Ringschlußmetathese mit verschiedenen Grubbs-Hoveyda-Katalysatoren, deren Mechanismus anhand von Umsatz-Zeit-Kurven kinetisch betrachtet wurde. Zum anderen die lichtinduzierte reversible Umwandlung eines Azobenzolderivates und dessen im Wässrigen einsetzende Zersetzungsreaktion. Zu guter Letzt wurde das photochemische Gleichgewicht eines Spiropyran/Merocyanin-Systems untersucht, Anteile der jeweiligen Form bestimmt und unterschiedliche Einflüsse wie Bestrahlungswellenlänge, Temperatur und Lösungsmittel auf das Gleichgewicht identifiziert.
Die Analyse der erwähnten Modellsysteme mit verschiedenen NMR-Methoden ermöglichte den Erhalt von neuen Erkenntnissen über die Modellsysteme und darüber hinaus auch Hinweise und Trends über das Verhalten anderer auf den Modellsystemen beruhender Katalysatoren oder photochromer Materialien. Die erhaltenen Ergebnisse befähigen zu einem rationalen Katalysatordesign und der Messung von – formal – komplexeren Materialien, die photochrome Gruppen beinhalten
Kurz vor der Reform: Arbeitsmarktinstrumente auf dem PrĂĽfstand
Eine der wichtigsten Aufgaben der aktiven Arbeitsmarktpolitik ist es, die Integration Arbeitsloser in das Erwerbsleben zu unterstützen. Um das Instrumentarium dafür sachgerecht auszugestalten, müssen Qualität und Wirkung der einzelnen Bausteine bekannt sein. Das IAB hat im Januar 2011 gemeinsam mit dem BMAS die bisher vorliegenden wissenschaftlichen Befunde zu den Instrumenten der Arbeitsmarktpolitik systematisch aufgearbeitet und im 'Sachstandsbericht der Evaluation der Instrumente' zusammengefasst. Dieser IAB-Kurzbericht stellt die - nach Instrumentengruppen gegliederten - zentralen Befunde des Sachstandsberichts und die daraus folgenden Empfehlungen vor. Er gibt damit einen kompakten Überblick über die Ergebnisse von Evaluationsprojekten in Deutschland
Mcl-1 Antisense Therapy Chemosensitizes Human Melanoma in a SCID Mouse Xenotransplantation Model
It is well established that high expression of the antiapoptotic Bcl-2 family proteins Bcl-2 and Bcl-xL can significantly contribute to chemoresistance in a number of human malignancies. Much less is known about the role the more recently described Bcl-2 family member Mcl-1 might play in tumor biology and resistance to chemotherapy. Using an antisense strategy, we here address this issue in melanoma, a paradigm of a treatment-resistant malignancy. After in vitro proof of principle supporting an antisense mechanism of action with specific reduction of Mcl-1 protein as a consequence of nuclear uptake of the Mcl-1 antisense oligonucleotides employed, antisense and universal control oligonucleotides were administered systemically in combination with dacarbazine in a human melanoma SCID mouse xenotransplantation model. Dacarbazine, available now for more than three decades, still remains the most active single agent for treatment of advanced melanoma. Mcl-1 antisense oligonucleotides specifically reduced target protein expression as well as the apoptotic threshold of melanoma xenotransplants. Combined Mcl-1 antisense oligonucleotide plus dacarbazine treatment resulted in enhanced tumor cell apoptosis and led to a significantly reduced mean tumor weight (mean 0.16 g, 95% confidence interval 0.08–0.26) compared to the tumor weight in universal control oligonucleotide plus dacarbazine treated animals (mean 0.35 g, 95% confidence interval 0.2–0.44) or saline plus dacarbazine treated animals (mean 0.39 g, 95% confidence interval 0.25–0.53). We thus show that Mcl-1 is an important factor contributing to the chemoresistance of human melanoma in vivo. Antisense therapy against the Mcl-1 gene product, possibly in combination with antisense strategies targeting other antiapoptotic Bcl-2 family members, appears to be a rational and promising approach to help overcome treatment resistance of malignant melanoma
Retinal Involvement in a Patient with Cerebral Manifestation of Chronic Graft-Versus-Host-Disease
Background: We report a 35-year-old female patient with cerebral manifestations of chronic graft-versus-host disease (cGvHD) and putative retinal involvement after allogeneic peripheral blood stem cell transplantation (alloHSCT). Patient and Methods: The patient experienced recurrent episodes of fever and encephalitic signs 7 months after alloHSCT during taper of immunosuppression (IS). Results: Cerebral magnetic resonance imaging (MRI) showed non-gadolinium-enhancing confluent periventricular lesions and cerebrospinal fluid inflammation. After exclusion of infectious causes, treatment with steroids and antiepileptics improved cognitive deficits. Steroid reduction provoked a relapse responding to IS. 2 years later, she complained of right-sided blurred vision and floaters; both eyes showed whitish circumscribed retinal infiltrations, cellular infiltration of the vitreous and mild bilateral optic disc edema. Oncological and neurological work-up ruled out infectious diseases and other GvHD manifestations. Symptoms and signs resolved under continued systemic IS, leaving pigmented retinal scars. After IS withdrawal, classical cutaneous cGvHD developed, resolving on systemic IS. 94 months after transplantation, she is doing well. Conclusion: To our knowledge, this is the first observation of retinal involvement of cerebral cGvHD manifestations with retinal infiltrations documented in the absence of other causes and in parallel to periventricular lesions in cerebral MRI. Based on bone marrow histology, we discuss a small vessel pathophysiology of cGvHD
Phenotypic Adaptation to Antiseptics and Effects on Biofilm Formation Capacity and Antibiotic Resistance in Clinical Isolates of Early Colonizers in Dental Plaque
Despite the wide-spread use of antiseptics in dental practice and oral care products, there is little public awareness of potential risks associated with antiseptic resistance and potentially concomitant cross-resistance. Therefore, the aim of this study was to investigate potential phenotypic adaptation in 177 clinical isolates of early colonizers of dental plaque (Streptococcus, Actinomyces, Rothia and Veillonella spp.) upon repeated exposure to subinhibitory concentrations of chlorhexidine digluconate (CHX) or cetylpyridinium chloride (CPC) over 10 passages using a modified microdilution method. Stability of phenotypic adaptation was re-evaluated after culture in antiseptic-free nutrient broth for 24 or 72 h. Strains showing 8-fold minimal inhibitory concentration (MIC)-increase were further examined regarding their biofilm formation capacity, phenotypic antibiotic resistance and presence of antibiotic resistance genes (ARGs). Eight-fold MIC-increases to CHX were detected in four Streptococcus isolates. These strains mostly exhibited significantly increased biofilm formation capacity compared to their respective wild-type strains. Phenotypic antibiotic resistance was detected to tetracycline and erythromycin, consistent with the detected ARGs. In conclusion, this study shows that clinical isolates of early colonizers of dental plaque can phenotypically adapt toward antiseptics such as CHX upon repeated exposure. The underlying mechanisms at genomic and transcriptomic levels need to be investigated in future studie
CsxFA1 xPb I1 yBry 3 Perovskite Compositions the Appearance of Wrinkled Morphology and its Impact on Solar Cell Performance
We report on the formation of wrinkle patterned surface morphologies in cesium formamidinium based CsxFA1 amp; 8722;xPb I1 amp; 8722;yBry 3 perovskite compositions with x 0 amp; 8722;0.3 and y 0 amp; 8722;0.3 under various spin coating conditions. By varying the Cs and Br contents, the perovskite precursor solution concentration and the spin coating procedure, the occurrence and characteristics of the wrinkle shaped morphology can be tailored systematically. Cs0.17FA0.83Pb I0.83Br0.17 3 perovskite layers were analyzed regarding their surface roughness, microscopic structure, local and overall composition, and optoelectronic properties. Application of these films in p amp; 8722;i amp; 8722;n perovskite solar cells PSCs with indium doped tin oxide NiOx perovskite C60 bathocu proine Cu architecture resulted in up to 15.3 and 17.0 power conversion efficiency for the flat and wrinkled morphology, respectively. Interestingly, we find slightly red shifted photoluminescence PL peaks for wrinkled areas and we are able to directly correlate surface topography with PL peak mapping. This is attributed to differences in the local grain size, whereas there is no indication for compositional demixing in the films. We show that the perovskite composition, crystallization kinetics, and layer thickness strongly influence the formation of wrinkles which is proposed to be related to the release of compressive strain during perovskite crystallization. Our work helps us to better understand film formation and to further improve the efficiency of PSCs with widely used mixed perovskite composition
Temporal Network Based Analysis of Cell Specific Vein Graft Transcriptome Defines Key Pathways and Hub Genes in Implantation Injury
Vein graft failure occurs between 1 and 6 months after implantation due to obstructive intimal hyperplasia, related in part to implantation injury. The cell-specific and temporal response of the transcriptome to vein graft implantation injury was determined by transcriptional profiling of laser capture microdissected endothelial cells (EC) and medial smooth muscle cells (SMC) from canine vein grafts, 2 hours (H) to 30 days (D) following surgery. Our results demonstrate a robust genomic response beginning at 2 H, peaking at 12–24 H, declining by 7 D, and resolving by 30 D. Gene ontology and pathway analyses of differentially expressed genes indicated that implantation injury affects inflammatory and immune responses, apoptosis, mitosis, and extracellular matrix reorganization in both cell types. Through backpropagation an integrated network was built, starting with genes differentially expressed at 30 D, followed by adding upstream interactive genes from each prior time-point. This identified significant enrichment of IL-6, IL-8, NF-κB, dendritic cell maturation, glucocorticoid receptor, and Triggering Receptor Expressed on Myeloid Cells (TREM-1) signaling, as well as PPARα activation pathways in graft EC and SMC. Interactive network-based analyses identified IL-6, IL-8, IL-1α, and Insulin Receptor (INSR) as focus hub genes within these pathways. Real-time PCR was used for the validation of two of these genes: IL-6 and IL-8, in addition to Collagen 11A1 (COL11A1), a cornerstone of the backpropagation. In conclusion, these results establish causality relationships clarifying the pathogenesis of vein graft implantation injury, and identifying novel targets for its prevention
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