Apoptosis in ventricular myocytes: the role of tumor suppressor proteins

Apoptosis or programmed cell death is an important physiologic event crucial for the selective removal of damaged or unwanted cells from body tissues. In the cardiovascular system, apoptosis has been observed in the vasculature and myocardium. Untimely or inappropriate myocardial cell loss through an apoptotic process may contribute to ventricular remodeling and the ultimate demise of ventricular function following injury. Therapeutic interventions designed to modulate or prevent myocardial apoptotic cell loss may therefore prove beneficial in maintaining cardiac function. Incite into the molecular mechanisms that govern apoptosis in mammalian cells has led to the identification of several key factors that promote or prevent the apoptotic process. In this report, we discuss putative regulators of cardiac cell apoptosis with specific reference to the tumor suppressor proteins, p53 and Rb. The interplay between these factors, as well as the anti-apoptotic molecules related to the Bcl-2 the family are discussed in the context of the heart under normal and disease conditions.     

Secondary and primary murine alveolar echinococcosis: combined albendazole/nitazoxanide chemotherapy exhibits profound anti-parasitic activity

In this study, the efficacies of chemotherapy employing nitazoxanide (NTZ), albendazole (ABZ), and a NTZ/ABZ-combination against alveolar echinococcosis (AE) were investigated in an experimental murine model. Following secondary infection, meaning i.p. injection of 20 Echinococcus multilocularis metacestodes, the drugs were administered by intragastric inoculation on a daily bases for a period of 5 weeks. Treatment was started either immediately on the day of infection, or at 2 months p.i., respectively. Application of the NTZ/ABZ-combination starting at 2 months p.i. was proven to be most effective in terms of reducing parasite weight (from 4.42+/-1.03 to 1+/-0.05 g; P=0.01). Inspection of treated parasites by transmission electron microscopy showed that ABZ- and NTZ-treated metacestode tissues, respectively, were heterogeneous in that both largely intact parasites as well as severely altered metacestodes could be observed. NTZ/ABZ-combination treatment induced the most severe ultrastructural alterations, including massive reduction in length and number of microtriches, severely damaged tegumental architecture, and progressive loss of viability of the germinal layer, associated with encapsulation by host connective tissue. A comparative pharmacokinetic study in mice revealed that the application of ABZ and NTZ in combination resulted in a two- to four-fold increase of albendazole sulfoxide serum levels for the period of 4-8 h following drug uptake compared to application of ABZ alone. In a third experiment, mice were orally infected with E. multilocularis eggs, and treated with NTZ starting at 2 months p.i. This resulted in a significantly lower lesion number in treated versus untreated mice (P=0.01). This investigation indicates the potential value for NTZ and/or a combined ABZ/NTZ chemotherapy against AE.     

Reconstitution of gamma-secretase activity

gamma-Secretase is a membrane protein complex with an unusual aspartyl protease activity that catalyses the regulated intramembranous cleavage of the beta-amyloid precursor protein (APP) to release the Alzheimer's disease (AD)-associated amyloid beta-peptide (Abeta) and the APP intracellular domain (AICD). Here we show the reconstitution of gamma-secretase activity in the yeast Saccharomyces cerevisiae, which lacks endogenous gamma-secretase activity. Reconstituted gamma-secretase activity depends on the presence of four complex components including presenilin (PS), nicastrin (Nct), APH-1 (refs 3-6) and PEN-2 (refs 4, 7), is associated with endoproteolysis of PS, and produces Abeta and AICD in vitro. Thus, the biological activity of gamma-secretase is reconstituted by the co-expression of human PS, Nct, APH-1 and PEN-2 in yeast.     

Effects of an isogenic Zn-metalloprotease-deficien mutant of Legionella pneumophila in a guinea-pig pneumonia model

To determine the effects, if any, of the Zn-metallo-protease on virulence of Legionella pneumophila infection, an isogenic mutant deficient in protease (encoded by the proA gene) was tested in an Acantha-moeba cell model, in guinea-pig macrophages, and in a guinea-pig pneumonia model. The cloned proA gene was completely inactivated by insertion of a kanamycin-resistance cassette into the protease gene of L. pneumophila AA100. This mutated gene was then introduced into the L. pneumophila chromosome by allelic exchange to form the isogenic ProA mutant AA200. AA200 showed no difference in its ability to enter, survive, or grow in Acanthamoeba and explanted guinea-pig macrophages; neither light nor electron microscopy revealed morphological differences in the eukaryotic cells infected with the protease mutant or the wild-type strains. The proA gene was found to be expressed in L. pneumophila during intracellular growth in amoebae by measuring the light produced from a truncated luxC gene fusion with the proA promoter. Virulence of the protease mutant was attenuated when tested in a guinea-pig model of infection employing the intratracheal Inoculation method. AA200 was slower to cause death, grew to lower numbers in the lungs, resulted in less necrotic debris and a larger macrophage infiltrate, and was more likely to be found in association with macrophage vacuoles than the parent strain.     

Trans-generational immune priming in a social insect

Detecting functional homology between invertebrate and vertebrate immunity is of interest in terms of understanding the dynamics and evolution of immune systems. Trans-generational effects on immunity are well known from vertebrates, but their existence in invertebrates remains controversial. Earlier work on invertebrates has interpreted increased offspring resistance to pathogens as trans-generational immune priming. However, interpretation of these earlier studies involves some caveats and thus full evidence for a direct effect of maternal immune experience on offspring immunity is still lacking in invertebrates. Here we show that induced levels of antibacterial activity are higher in the worker offspring of the bumblebee, Bombus terrestris L. when their mother queen received a corresponding immune challenge prior to colony founding. This shows trans-generational immune priming in an insect, with ramifications for the evolution of sociality.     

A combination of different mass spectroscopic techniques for the analysis of dynamic changes of histone modifications

The N-terminal tails of the histones are subject to many enzyme-mediated post-translational modifications, such as lysine acetylation, lysine and arginine methylation, serine phosphorylation, poly-ADP ribosylation and the attachment of the small peptide ubiquitin. These modifications, singly or in combination, are thought to generate an epigenetic code that specifies different patterns of gene activity. We present a detailed study on the mapping of histone post-translational modifications using a combination of matrix-assisted laser desorption/ionization-time of flight and electrospray ionization tandem mass spectrometry analysis of peptides generated by protease cleavage of individual histones isolated from different developmental stages. Due to their high content in basic amino acid residues and in order to be able to quantitatively compare two different samples we developed a chemical derivatization protocol. This strategy enabled us to determine the primary sequence of the peptides and to unambiguously assign specific modifications. This method is generally applicable to histone samples from various sources and can be used to study changes of modification patterns during early embryonic development or tissue differentiation and regeneration.     

Segmental identity and cerebellar granule cell induction in rhombomere 1

Background  

Cerebellar granule cell precursors are specifically generated within the hindbrain segment, rhombomere 1, which is bounded rostrally by the midbrain/hindbrain isthmus and caudally by the boundary of the Hoxa2 expression domain. While graded signals from the isthmus have a demonstrable patterning role within this region, the significance of segmental identity for neuronal specification within rhombomere 1 is unexplored. We examined the response of granule cell precursors to the overexpression of Hoxa2, which normally determines patterns of development specific to the hindbrain. How much does the development of the cerebellum, a midbrain/hindbrain structure, reflect its neuromeric origin as a hindbrain segment?