Booster vaccination against tetanus and diphtheria: insufficient protection against diphtheria in young and elderly adults

We have recently demonstrated that single shot vaccinations against tetanus and diphtheria do not lead to long-lasting immunity against diphtheria in elderly persons despite administration at 5 year intervals. In the present study we have immunized a group of young adults against tetanus and diphtheria to compare the pre- and 28 days post-vaccination immune responses in the young group with results of the same vaccination performed in an elderly group of a previous study. We also studied protection in both groups 5 years after vaccination. We compared antibody titers at all three time points and also analyzed the T cell responses in both age groups 5 years after vaccination.Before vaccination 9 % of the elderly persons were not protected against tetanus, and 48 % did not have protection against diphtheria. In the young group all participants were protected against tetanus, but 52 % were also unprotected against diphtheria before vaccination. 28 days after vaccination 100 % of all participants had protective antibody concentrations against tetanus and only a small percentage in each age group (<10 %) was unprotected against diphtheria. 5 years later, 100 % of both cohorts were still protected against tetanus, but 24 % of the young and 54 % of the elderly group were unprotected against diphtheria. Antibody concentrations against diphtheria measured by ELISA correlated well with their neutralizing capacity. T cell responses to tetanus and diphtheria did not differ between young and old persons. We conclude that booster vaccinations against tetanus and diphtheria according to present recommendations provide long-lasting protection only against tetanus, but not against diphtheria, independently of age. In elderly persons, the level of protection is even lower, probably due to intrinsic age-related changes within the immune system and/or insufficient vaccination earlier in life.     

Metformin inhibits proliferation and migration of glioblastoma cells independently of TGF-β2

To this day, glioblastoma (GBM) remains an incurable brain tumor. Previous research has shown that metformin, an oral anti-diabetic drug, may decrease GBM cell proliferation and migration especially in brain tumor initiating cells (BTICs). As transforming growth factor β 2 (TGF-β₂) has been reported to promote high-grade glioma and is inhibited by metformin in other tumors, we explored whether metformin directly interferes with TGF-β₂-signaling. Functional investigation of proliferation and migration of primary BTICs after treatment with metformin+/?TGF-β₂ revealed that metformin doses as low as 0.01 mM metformin thrice a day were able to inhibit proliferation of susceptible cell lines, whereas migration was impacted only at higher doses. Known cellular mechanisms of metformin, such as increased lactate secretion, reduced oxygen consumption and activated AMPK-signaling, could be confirmed. However, TGF-β₂ and metformin did not act as functional antagonists, but both rather inhibited proliferation and/or migration, if significant effects were present. We did not observe a relevant influence of metformin on TGF-β₂ mRNA expression (qRT-PCR), TGF-β₂ protein expression (ELISA) or SMAD-signaling (Western blot). Therefore, it seems that metformin does not exert its inhibitory effects on GBM BTIC proliferation and migration by altering TGF-β₂-signaling. Nonetheless, as low doses of metformin are able to reduce proliferation of certain GBM cells, further exploration of predictors of BTICs' susceptibility to metformin appears justified.     

Neuropädiatrische Differenzialdiagnostik der Mikrozephalie im Kindesalter

Microcephaly affects 2–3?% of the population and is often associated with intellectual disability. The underlying reduction in brain volume can result from various exogenous factors or genetic causes. Microcephaly remains a poorly defined condition lacking both uniform diagnostic approaches and classification. A definite etiological diagnosis is the key to predict the prognosis, identify co-morbidities and offer genetic counseling. In addition, the identification of the underlying cause increases our knowledge of brain development and the clinical spectrum of microcephaly. We propose a diagnostic approach for children with microcephaly from a pediatric neurologist point of view.     

A genetic screen for modifiers of the delta1-dependent notch signaling function in the mouse

The Notch signaling pathway is an evolutionarily conserved transduction pathway involved in embryonic patterning and regulation of cell fates during development. Recent studies have demonstrated that this pathway is integral to a complex system of interactions, which are also involved in distinct human diseases. Delta1 is one of the known ligands of the Notch receptors. Mice homozygous for a loss-of-function allele of the Delta1 gene Dll1(lacZ/lacZ) die during embryonic development. Here, we present the results of two phenotype-driven modifier screens. Heterozygous Dll1(lacZ) knockout animals were crossed with ENU-mutagenized mice and screened for dysmorphological, clinical chemical, and immunological variants that are dependent on the Delta1 loss-of-function allele. First, we show that mutagenized heterozygous Dll1(lacZ) offspring have reduced body weight and altered specific clinical chemical parameters, including changes in metabolites and electrolytes relevant for kidney function. In our mutagenesis screen we have successfully generated 35 new mutant lines. Of major interest are 7 mutant lines that exhibit a Dll1(lacZ/+)-dependent phenotype. These mutant mouse lines provide excellent in vivo tools for studying the role of Notch signaling in kidney and liver function, cholesterol and iron metabolism, cell-fate decisions, and during maturation of T cells in the immune system.     

Mitochondrial oxidative stress causes hyperphosphorylation of tau

Age-related neurodegenerative disease has been mechanistically linked with mitochondrial dysfunction via damage from reactive oxygen species produced within the cell. We determined whether increased mitochondrial oxidative stress could modulate or regulate two of the key neurochemical hallmarks of Alzheimer's disease (AD): tau phosphorylation, and beta-amyloid deposition. Mice lacking superoxide dismutase 2 (SOD2) die within the first week of life, and develop a complex heterogeneous phenotype arising from mitochondrial dysfunction and oxidative stress. Treatment of these mice with catalytic antioxidants increases their lifespan and rescues the peripheral phenotypes, while uncovering central nervous system pathology. We examined sod2 null mice differentially treated with high and low doses of a catalytic antioxidant and observed striking elevations in the levels of tau phosphorylation (at Ser-396 and other phospho-epitopes of tau) in the low-dose antioxidant treated mice at AD-associated residues. This hyperphosphorylation of tau was prevented with an increased dose of the antioxidant, previously reported to be sufficient to prevent neuropathology. We then genetically combined a well-characterized mouse model of AD (Tg2576) with heterozygous sod2 knockout mice to study the interactions between mitochondrial oxidative stress and cerebral Ass load. We found that mitochondrial SOD2 deficiency exacerbates amyloid burden and significantly reduces metal levels in the brain, while increasing levels of Ser-396 phosphorylated tau. These findings mechanistically link mitochondrial oxidative stress with the pathological features of AD.     

Noncompaction of the ventricular myocardium is associated with a de novo mutation in the beta-myosin heavy chain gene

Noncompaction of the ventricular myocardium (NVM) is the morphological hallmark of a rare familial or sporadic unclassified heart disease of heterogeneous origin. NVM results presumably from a congenital developmental error and has been traced back to single point mutations in various genes. The objective of this study was to determine the underlying genetic defect in a large German family suffering from NVM. Twenty four family members were clinically assessed using advanced imaging techniques. For molecular characterization, a genome-wide linkage analysis was undertaken and the disease locus was mapped to chromosome 14ptel-14q12. Subsequently, two genes of the disease interval, MYH6 and MYH7 (encoding the alpha- and beta-myosin heavy chain, respectively) were sequenced, leading to the identification of a previously unknown de novo missense mutation, c.842G>C, in the gene MYH7. The mutation affects a highly conserved amino acid in the myosin subfragment-1 (R281T). In silico simulations suggest that the mutation R281T prevents the formation of a salt bridge between residues R281 and D325, thereby destabilizing the myosin head. The mutation was exclusively present in morphologically affected family members. A few members of the family displayed NVM in combination with other heart defects, such as dislocation of the tricuspid valve (Ebstein's anomaly, EA) and atrial septal defect (ASD). A high degree of clinical variability was observed, ranging from the absence of symptoms in childhood to cardiac death in the third decade of life. The data presented in this report provide first evidence that a mutation in a sarcomeric protein can cause noncompaction of the ventricular myocardium.     

Impact of Land-use Change on Dengue and Malaria in Northern Thailand

Land-use change, a major constituent of global environmental change, potentially has significant consequences for human health in relation to mosquito-borne diseases. Land-use change can influence mosquito habitat, and therefore the distribution and abundance of vectors, and land use mediates human–mosquito interactions, including biting rate. Based on a conceptual model linking the landscape, people, and mosquitoes, this interdisciplinary study focused on the impacts of changes in land use on dengue and malaria vectors and dengue transmission in northern Thailand. Extensive data on mosquito presence and abundance, land-use change, and infection risk determinants were collected over 3 years. The results of the different components of the study were then integrated through a set of equations linking land use to disease via mosquito abundance. The impacts of a number of plausible scenarios for future land-use changes in the region, and of concomitant behavioral change were assessed. Results indicated that land-use changes have a detectable impact on mosquito populations and on infection. This impact varies according to the local environment but can be counteracted by adoption of preventive measures.     

The WW domain protein PRO40 is required for fungal fertility and associates with Woronin bodies

Fruiting body formation in ascomycetes is a highly complex process that is under polygenic control and is a fundamental part of the fungal sexual life cycle. However, the molecular determinants regulating this cellular process are largely unknown. Here we show that the sterile pro40 mutant is defective in a 120-kDa WW domain protein that plays a pivotal role in fruiting body maturation of the homothallic ascomycete Sordaria macrospora. Although WW domains occur in many eukaryotic proteins, homologs of PRO40 are present only in filamentous ascomycetes. Complementation analysis with different pro40 mutant strains, using full-sized or truncated versions of the wild-type pro40 gene, revealed that the C terminus of PRO40 is crucial for restoring the fertile phenotype. Using differential centrifugation and protease protection assays, we determined that a PRO40-FLAG fusion protein is located within organelles. Further microscopic investigations of fusion proteins with DsRed or green fluorescent protein polypeptides showed a colocalization of PRO40 with HEX-1, a Woronin body-specific protein. However, the integrity of Woronin bodies is not affected in mutant strains of S. macrospora and Neurospora crassa, as shown by fluorescence microscopy, sedimentation, and immunoblot analyses. We discuss the function of PRO40 in fruiting body formation.