Investigation of the biosynthesis of bacterial natural products
- Natural products (NPs) have been a rich source for pharmaceutically used anti-infectives and other drugs. However, the application of anti-infectives inevitably causes the development of resistant and multiresistant pathogens, which have to be treated with novel anti-infectives. The industrial research for novel anti-infectives has been concentrating on members of the bacterial Actinomycetales for a long time. Due to several reasons, e.g. the rediscovery of already known NPs, pharmaceutical companies abandoned their NP-research and focused on drug development based on combinatorial chemistry. However, the limited structural diversity of merely synthetic compound libraries has not been a fruitful source for bioactive compounds. Hence the discovery of novel bioactive NPs as a source for anti-infectives is still of economical and humanitarian interest and will remain to be an important branch of research in the future. One strategy to circumvent the rediscovery of bioactive NPs is the analysis of yet unexplored bacterial taxa. Based on this assumption, this work aimed at the discovery of novel NPs from the entomopathogenic bacterial genera Xenorhabdus and Photorhabdus and other promising taxa, as well as the investigation of their biosynthesis. ...
Certolizumab pegol in rheumatoid arthritis patients with low to moderate activity: the CERTAIN double-blind, randomised, placebo-controlled trial
Josef S. Smolen
Owen R. Davies
- This 52-week, randomised, double-blind phase IIIb study assessed efficacy and safety of certolizumab pegol (CZP) as add-on therapy to non-biologic disease-modifying antirheumatic drugs (DMARDs) in rheumatoid arthritis (RA) patients with low to moderate disease activity, and stopping therapy in patients in sustained remission.
METHODS:Patients were randomised 1:1 to CZP (400 mg at weeks 0, 2 and 4, then 200 mg every 2 weeks) or placebo (every 2 weeks) plus current non-biologic DMARDs. At week 24, patients who achieved the primary endpoint of Clinical Disease Activity Index (CDAI) remission at both weeks 20 and 24 stopped study treatment and continued in the study until week 52.
RESULTS: Of 194 patients (CZP=96; placebo=98), >90% had moderate disease activity at baseline. Significantly more CZP patients met the primary endpoint than placebo patients (week 20 and 24 CDAI remission rates: 18.8% vs 6.1%; p≤0.05). At week 24, 63.0% vs 29.7% of CZP versus placebo patients (p<0.001) achieved LDA. Disease activity score (ESR) based on 28-joint count and Simplified Disease Activity Index remission rates were also significantly higher with CZP versus placebo (19.8% vs 3.1%; p≤0.01 and 14.6% vs 4.1%; p≤0.05). CZP patients reported improvements in physical function versus placebo (mean Health Assessment Questionnaire-Disability-Index change from baseline: CZP, -0.25 vs placebo, -0.03; p≤0.01). During the period following withdrawal of CZP or placebo, only 3/17 prior CZP patients and 2/6 prior placebo patients maintained CDAI remission until week 52, but CZP reinstitution allowed renewed improvement. Adverse and serious adverse event rates were comparable between CZP and placebo groups.
CONCLUSIONS: Addition of CZP to non-biologic DMARDs is an effective treatment in RA patients with predominantly moderate disease activity, allowing low-disease activity or remission to be reached in a majority of the patients. However, the data suggest that CZP cannot be withdrawn in patients achieving remission.
Genetic diversity and geneflow between Arctic and Antarctic populations of the lichen Cetraria aculeata along the Andes and the Rocky Mountains
Fernando Fernández Mendoza
- Lichens are present in most land ecosystems, frequently occupying habitats where few other organisms are able to survive. Their contribution to the ecosystems in terms of biomass and ground cover increases with latitude and altitude, being, together with bryophytes, the most conspicuous component of alpine and polar landscapes. Whereas some polar lichens have reduced distributions and are restricted to high latitudes, most of them have very wide distributional ranges, which oven extend over several climatic regions. Many of them are common to Polar Regions of both hemispheres, a distributional pattern that has been denominated as bipolar, antitropical or amphitropical. Bipolar distributions are not exclusive to lichens, but common to many groups of organisms. The bipolar element in lichens is exceptional as it includes a large number of species, while in most other land organisms it includes genera or families but very seldom species.
In this dissertation I use the bipolar lichen Cetraria aculeata to give a first insight into the phylogeography of this biogeographic element in lichens. I discuss how and when the disjunct distribution of C. aculeata came to be, and try to partial out the roles that historical and ecological processes played in shaping its distribution.
Sampling was designed to cover a wide geographic extension. The main e"ort was made to collect in boreal, temperate and tropical mountain ranges in North and South America, as well to include Mediterranean populations in which specimens with deviant morphologies are observed.
I found that Cetraria aculeata forms a genetically congruent taxon. Although whether it should include C. muricata remains unsolved, I excluded all specimens identified as the latter from our analyses. Thee populations of both algal and fungal symbionts have a strong geographic structure. The study of the lichen fungus suggested that the species originated in the Eurasian continent and later expanded to acquire its current distribution during the Pleistocene. The results showed that all American populations originated from an ancestral population, more similar to the extant Arctic populations than to the Mediterranean ones.
The comparison between the structure of fungal and algal populations showed a high degree of coherence between them. However, the similarity in photobiont use between Arctic and Antarctic populations suggests that photobiont use responds not only to a history of codispersal in vegetative propagula, but it is also a result of a selective process related to climate. Since this climatic pattern of similarity is also found in the community of Alphaproteobacteria associated with C. aculeata, we concluded that lichens might be able to accommodate or to respond to different environmental conditions by selectively associating with different symbiotic partners.
Lastly, we found the Mediterranean populations of C. aculeata to be genetically differentiated in algal and fungal symbionts from the rest of the populations. While we found no grounds to believe that the overgrown morphs encountered in the region are due to the association with different algal lineages, I believe that a switch in photobiont use might be responsible for the pattern of genetic isolation encountered. Furthermore, I suggest that the Mediterranean and bipolar C. aculeata could be two different species, since both are ecologically, genetically and at least in part morphologically divergent.
Life insurance demand under health shock risk
Lorenz S. Schendel
- This paper studies the life cycle consumption-investment-insurance problem of a family. The wage earner faces the risk of a health shock that significantly increases his probability of dying. The family can buy term life insurance with realistic features. In particular, the available contracts are long term so that decisions are sticky and can only be revised at significant costs. Furthermore, a revision is only possible as long as the insured person is healthy. A second important and realistic feature of our model is that the labor income of
the wage earner is unspanned. We document that the combination of unspanned labor income and the stickiness of insurance decisions reduces the insurance demand significantly. This is because an income shock induces the need to reduce the insurance coverage, since premia become less affordable. Since such a reduction is costly and families anticipate these potential costs, they buy less protection at all ages. In particular, young families stay away from life insurance markets altogether.
Survival According to BRAF-V600 Tumor Mutations – An Analysis of 437 Patients with Primary Melanoma
Thomas K. Eigentler
Andreas von Deimling
- The prognostic impact of BRAF-V600 tumor mutations in stage I/II melanoma patients has not yet been analyzed in detail. We investigated primary tumors of 437 patients diagnosed between 1989 and 2006 by Sanger sequencing. Mutations were detected in 38.7% of patients and were associated with age, histological subtype as well as mitotic rate. The mutational rate was 36.7% in patients with disease-free course and 51.7% in those with subsequent distant metastasis (p = 0.031). No difference in overall survival (p = 0.119) but a trend for worse distant-metastasis-free survival (p = 0.061) was observed in BRAF mutant compared to BRAF wild-type patients. Independent prognostic factors for overall survival were tumor thickness, mitotic rate and ulceration. An interesting significant prognostic impact was observed in patients with tumor thickness of 1 mm or less, with the mutation present in 6 of 7 patients dying from melanoma. In conclusion, no significant survival differences were found according to BRAF-V600 tumor mutations in patients with primary melanoma but an increasing impact of the mutational status was observed in the subgroup of patients with tumor thickness of 1 mm or less. A potential role of the mutational status as a prognostic factor especially in this subgroup needs to be investigated in larger studies.
Upregulation of APP, ADAM10 and ADAM17 in the Denervated Mouse Dentate Gyrus
Domenico Del Turco
- The disintegrin and metalloproteinases ADAM10 and ADAM17 are regarded as the most important α-secretases involved in the physiological processing of amyloid precursor protein (APP) in brain. Since it has been suggested that processing of APP by α-secretases could be involved in the reorganization of the brain following injury, we studied mRNA expression of the two α-secretases Adam10 and Adam17, the ß-secretase Bace1, and the App-gene family (App, Aplp1, Aplp2) in the dentate gyrus of the mouse following entorhinal denervation. Using laser microdissection, tissue was harvested from the outer molecular layer and the granule cell layer of the denervated dentate gyrus. Expression levels of candidate genes were assessed using Affymetrix GeneChip Mouse Gene 1.0 ST arrays and reverse transcription-quantitative PCR, revealing an upregulation of Adam10 mRNA and Adam17 mRNA in the denervated outer molecular layer and an upregulation of Adam10 mRNA and App mRNA in the dentate granule cell layer. Immunolabeling for ADAM10 or ADAM17 in combination with markers for astro- and microglia revealed an increased labeling of ADAM10 and ADAM17 in the denervated outer molecular layer that was associated with reactive astrocytes but not with microglia. Collectively, these data show that denervation affects the expression level of APP and its two most important α-secretases. This suggests that APP-processing could be shifted towards the non-amyloidogenic pathway in denervated areas of the brain and, thus, towards the formation of neuroprotective APP cleavage products, such as APPsα.
Inflammatory Conditions Induce IRES-Dependent Translation of cyp24a1
Michael M. Kunze
Thilo F. Brauß
Magdalena M. Bajer
- Rapid alterations in protein expression are commonly regulated by adjusting translation. In addition to cap-dependent translation, which is e.g. induced by pro-proliferative signaling via the mammalian target of rapamycin (mTOR)-kinase, alternative modes of translation, such as internal ribosome entry site (IRES)-dependent translation, are often enhanced under stress conditions, even if cap-dependent translation is attenuated. Common stress stimuli comprise nutrient deprivation, hypoxia, but also inflammatory signals supplied by infiltrating immune cells. Yet, the impact of inflammatory microenvironments on translation in tumor cells still remains largely elusive. In the present study, we aimed at identifying translationally deregulated targets in tumor cells under inflammatory conditions. Using polysome profiling and microarray analysis, we identified cyp24a1 (1,25-dihydroxyvitamin D3 24-hydroxylase) to be translationally upregulated in breast tumor cells co-cultured with conditioned medium of activated monocyte-derived macrophages (CM). Using bicistronic reporter assays, we identified and validated an IRES within the 5′ untranslated region (5′UTR) of cyp24a1, which enhances translation of cyp24a1 upon CM treatment. Furthermore, IRES-dependent translation of cyp24a1 by CM was sensitive to phosphatidyl-inositol-3-kinase (PI3K) inhibition, while constitutive activation of Akt sufficed to induce its IRES activity. Our data provide evidence that cyp24a1 expression is translationally regulated via an IRES element, which is responsive to an inflammatory environment. Considering the negative feedback impact of cyp24a1 on the vitamin D responses, the identification of a novel, translational mechanism of cyp24a1 regulation might open new possibilities to overcome the current limitations of vitamin D as tumor therapeutic option.
Lateralization of Travelling Wave Response in the Hearing Organ of Bushcrickets
Arun Palghat Udayashankar
- Travelling waves are the physical basis of frequency discrimination in many vertebrate and invertebrate taxa, including mammals, birds, and some insects. In bushcrickets (Tettigoniidae), the crista acustica is the hearing organ that has been shown to use sound-induced travelling waves. Up to now, data on mechanical characteristics of sound-induced travelling waves were only available along the longitudinal (proximal-distal) direction. In this study, we use laser Doppler vibrometry to investigate in-vivo radial (anterior-posterior) features of travelling waves in the tropical bushcricket Mecopoda elongata. Our results demonstrate that the maximum of sound-induced travelling wave amplitude response is always shifted towards the anterior part of the crista acustica. This lateralization of the travelling wave response induces a tilt in the motion of the crista acustica, which presumably optimizes sensory transduction by exerting a shear motion on the sensory cilia in this hearing organ.
The small fibrinopeptide bβ15-42 as renoprotective agent preserving the endothelial and vascular integrity in early ischemia reperfusion injury in the mouse kidney and vascular integrity in early ischemia reperfusion injury in the mouse kidney
- Disruption of the renal endothelial integrity is pivotal for the development of a vascular leak, tissue edema and consequently acute kidney injury. Kidney ischemia amplifies endothelial activation and up-regulation of pro-inflammatory mechanisms. After restoring a sufficient blood flow, the kidney is damaged through complex pathomechanisms that are classically referred to as ischemia and reperfusion injury, where the disruption of the inter-endothelial connections seems to be a crucial step in this pathomechanism. Focusing on the molecular cell-cell interaction, the fibrinopeptide Bβ15–42 prevents vascular leakage by stabilizing these inter-endothelial junctions. The peptide associates with vascular endothelial-cadherin, thus preventing early kidney dysfunction by preserving blood perfusion efficacy, edema formation and thus organ dysfunction. We intended to demonstrate the early therapeutic benefit of intravenously administered Bβ15–42 in a mouse model of renal ischemia and reperfusion. After 30 minutes of ischemia, the fibrinopeptide Bβ15–42 was administered intravenously before reperfusion was commenced for 1 and 3 hours. We show that Bβ15–42 alleviates early functional and morphological kidney damage as soon as 1 h and 3 h after ischemia and reperfusion. Mice treated with Bβ15–42 displayed a significantly reduced loss of VE-cadherin, indicating a conserved endothelial barrier leading to less neutrophil infiltration which in turn resulted in significantly reduced structural renal damage. The significant reduction in tissue and serum neutrophil gelatinase-associated lipocalin levels reinforced our findings. Moreover, renal perfusion analysis by color duplex sonography revealed that Bβ15–42 treatment preserved resistive indices and even improved blood velocity. Our data demonstrate the efficacy of early therapeutic intervention using the fibrinopeptide Bβ15–42 in the treatment of acute kidney injury resulting from ischemia and reperfusion. In this context Bβ15–42 may act as a potent renoprotective agent by preserving the endothelial and vascular integrity.
Early postoperative serum cystatin C predicts severe acute kidney injury following cardiac surgery: a post-hoc analysis of a randomized controlled trial
Ulrich A. Stock
- OBJECTIVE: Acute kidney injury (AKI) after cardiac surgery procedures is associated with poor patient outcomes. Cystatin C as a marker for renal failure has been shown to be of prognostic value; however, a wide range of its predictive accuracy has been reported. The aim of the study was to evaluate whether the measurement of pre- and postoperative serum cystatin C improves the prediction of AKI.
METHODS: In a single-centre, prospective study of 70 patients (74 ± 9ys; range 47-85ys; 77% male), cystatin C was measured six times: (T1 = preoperative, T2 = start cardiopulmonary bypass (CPB), T3 = 20 min after CPB, T4 = end of operation; T5 = 24 h postoperatively; T6 = 7d postoperatively). Predictive property, in terms of the need for renal replacement therapy (RRT), was analysed by receiver operating characteristics (ROC) statistics and described by the area under the curve (AUC).
RESULTS: With respect to RRT (n = 8), serum cystatin C was significantly higher at the end of the operation (T4), 24 h postoperatively at T5 and at T6. The AUCs for preoperative T1 and intraoperative T2/3 cystatin C were <0.7 (95% CI, 0.47-0.85). The earliest significant predictive AUCs were found at the end of the operation (T4: p = 0.03 95% CI 0.58-0.88 AUC 0.73) and 24 h postoperatively (T5: p = 0.003 95% CI 0.74-0.96 AUC 0.85).
CONCLUSIONS: Early postoperative serum cystatin C increase appears to be a moderate biomarker in the prediction of AKI, whereas a preoperative and intraoperative cystatin C increase has only a limited diagnostic and predictive value.