Application of bacteria as self-healing agent for the development of sustainable concrete

The application of concrete is rapidly increasing worldwide and therefore the development of sustainable concrete is urgently needed for environmental reasons. As presently about 7% of the total anthropogenic atmospheric CO₂ emission is due to cement production, mechanisms that would contribute to a longer service life of concrete structures would make the material not only more durable but also more sustainable. One such mechanism that receives increasing attention in recent years is the ability for self-repair, i.e. the autonomous healing of cracks in concrete. In this study we investigated the potential of bacteria to act as self-healing agent in concrete, i.e. their ability to repair occurring cracks. A specific group of alkali-resistant spore-forming bacteria related to the genus Bacillus was selected for this purpose. Bacterial spores directly added to the cement paste mixture remained viable for a period up to 4 months. A continuous decrease in pore size diameter during cement stone setting probably limited life span of spores as pore widths decreased below 1 μm, the typical size of Bacillus spores. However, as bacterial cement stone specimens appeared to produce substantially more crack-plugging minerals than control specimens, the potential application of bacterial spores as self-healing agent appears promising.     

PCR-Denaturing Gradient Gel Electrophoresis of Complex Microbial Communities: A Two-Step Approach to Address the Effect of Gel-to-Gel Variation and Allow Valid Comparisons Across a Large Dataset

Denaturing gradient gel electrophoresis (DGGE) is widely used in microbial ecology to profile complex microbial communities over time and in response to different stimuli. However, inherent gel-to-gel variability has always been a barrier toward meaningful interpretation of DGGE profiles obtained from multiple gels. To address this problem, we developed a two-step methodology to align DGGE profiles across a large dataset. The use of appropriate inter-gel standards was of vital importance since they provided the basis for efficient within- and between-gel alignment and a reliable means to evaluate the final outcome of the process. Pretreatment of DGGE profiles by a commercially available image analysis software package (TL120 v2006, Phoretix 1D Advanced) followed by a simple interpolation step in Matlab minimized the effect of gel-to-gel variation, allowing for comparisons between large numbers of samples with a high degree of confidence. At the same time, data were obtained in the form of whole densitometric curves, rather than as band presence/absence or intensity information, and could be readily analyzed by a collection of well-established multivariate methods. This work clearly demonstrates that there is still room for significant improvements as to the way large DGGE datasets are processed and statistically interrogated.     

Rheumatoid arthritis–associated autoantibodies in non–rheumatoid arthritis patients with mucosal inflammation: a case–control study

IntroductionRheumatoid arthritis–associated autoantibodies (RA-AAB) can be present in serum years before clinical onset of rheumatoid arthritis (RA). It has been hypothesized that initiation of RA-AAB generation occurs at inflamed mucosal surfaces, such as in the oral cavity or lungs. The aim of this study was to assess systemic presence of RA-AAB in patients without RA who had oral or lung mucosal inflammation.MethodsThe presence of RA-AAB (immunoglobulin A [IgA] and IgG anti-cyclic citrullinated peptide 2 antibodies (anti-CCP2), IgM and IgA rheumatoid factor (RF), IgG anti-carbamylated protein antibodies and IgG and IgA anti-citrullinated peptide antibodies against fibrinogen, vimentin and enolase) were determined in sera of non-RA patients with periodontitis (PD, n = 114), bronchiectasis (BR, n = 80) or cystic fibrosis (CF, n = 41). Serum RA-AAB levels were compared with those of periodontally healthy controls (n = 36). Patients with established RA (n = 86) served as a reference group. Association of the diseases with RA-AAB seropositivity was assessed with a logistic regression model, adjusted for age, sex and smoking.ResultsLogistic regression analysis revealed that IgG anti-CCP seropositivity was associated with BR and RA, whereas the association with PD was borderline significant. IgA anti-CCP seropositivity was associated with CF and RA. IgM RF seropositivity was associated with RA, whereas the association with BR was borderline significant. IgA RF seropositivity was associated with CF and RA. Apart from an influence of smoking on IgA RF in patients with RA, there was no influence of age, sex or smoking on the association of RA-AAB seropositivity with the diseases. Anti-CarP levels were increased only in patients with RA. The same held for IgG reactivity against all investigated citrullinated peptides.ConclusionAlthough overall levels were low, RA-AAB seropositivity was associated with lung mucosal inflammation (BR and CF) and may be associated with oral mucosal inflammation (PD). To further determine whether mucosal inflammation functions as a site for induction of RA-AAB and precedes RA, longitudinal studies are necessary in which RA-AAB of specifically the IgA isotype should be assessed in inflamed mucosal tissues and/or in their inflammatory exudates.     

Evolutionary genetics: evolution with foresight

Evolution has no foresight, but produces ad hoc solutions by tinkering with available variation. A new study demonstrates how evolution nevertheless prepares organisms for the future by increasing their evolvability.     

Study of the interaction between ofloxacin and human serum albumin by spectroscopic methods

The binding of ofloxacin (OFLX) to human serum albumin (HSA) was investigated by fluorescence and circular dichroism (CD) techniques. The binding parameters have been evaluated by a fluorescence quenching method. Competitive binding measurements were performed in the presence of warfarin and ibuprofen and suggest binding to the warfarin site I of HSA. The distance r between donor (HSA) and acceptor (OFLX) was estimated according to the Forster's theory of non‐radiatiative energy transfer. CD spectra revealed that the binding of OFLX to HSA induced conformational changes in HSA. Molecular docking was performed and shows that for the lowest energy complex OFLX is located in site I of HSA, which correlate to the competitive binding experiments. Copyright © 2011 John Wiley & Sons, Ltd.     

Autosomal recessive dilated cardiomyopathy due to DOLK mutations results from abnormal dystroglycan O-mannosylation

Genetic causes for autosomal recessive forms of dilated cardiomyopathy (DCM) are only rarely identified, although they are thought to contribute considerably to sudden cardiac death and heart failure, especially in young children. Here, we describe 11 young patients (5-13 years) with a predominant presentation of dilated cardiomyopathy (DCM). Metabolic investigations showed deficient protein N-glycosylation, leading to a diagnosis of Congenital Disorders of Glycosylation (CDG). Homozygosity mapping in the consanguineous families showed a locus with two known genes in the N-glycosylation pathway. In all individuals, pathogenic mutations were identified in DOLK, encoding the dolichol kinase responsible for formation of dolichol-phosphate. Enzyme analysis in patients' fibroblasts confirmed a dolichol kinase deficiency in all families. In comparison with the generally multisystem presentation in CDG, the nonsyndromic DCM in several individuals was remarkable. Investigation of other dolichol-phosphate dependent glycosylation pathways in biopsied heart tissue indicated reduced O-mannosylation of alpha-dystroglycan with concomitant functional loss of its laminin-binding capacity, which has been linked to DCM. We thus identified a combined deficiency of protein N-glycosylation and alpha-dystroglycan O-mannosylation in patients with nonsyndromic DCM due to autosomal recessive DOLK mutations.