Interendothelial junctions in kidney vessels

Summary The interendothelial junctions of all segments of the renal vasculature have been studied in eight species using the freeze-fracture technique. Three types of junctions have been found. Combinations of tight and gap junction elements are characteristic for interlobular arteries and proximal afferent arterioles. Continuous tight junction strands not subdivided into individual particles are typical for the glomerular arterioles close to the glomerulus and the vasa recta. The interendothelial junctions of glomerular and peritubular capillaries and cortical veins are characterized by slight elevations decorated with sparse arrays of particles on the P-face of the endothelial cell plasma membrane.These studies were supported by the German Research Foundation within the SFB 90 Cardiovascular System.     

Gap junctional coupling between the JGA and the glomerular tuft

Summary Cytochalasin B (CB) administered simultaneously with a mitogenic dose of concanavalin A (Con A) interferes with the activation process. This interference involves structural alterations of cellular membrane which do not include a reduced Con A-binding capacity. This conclusion is supported by the observation of deformities in both nuclear and cytoplasmic membranes in Con A-activated lymphocytes subsequently treated with CB. The high incidence of membrane blebs and pseudomyelin bodies in the cytoplasm points to a general effect of CB on the structural organization of membrane which may secondarily interfere with some specific event such as generation or transfer of signals for activation or cytokinesis.     

Synaptopodin: An Actin-associated Protein in Telencephalic Dendrites and Renal Podocytes

Transforming growth factor-β (TGFβ) is a dimeric peptide growth factor which regulates cellular differentiation and proliferation during development. Most cells secrete TGFβ as a large latent TGFβ complex containing mature TGFβ, latency associated peptide, and latent TGFβ-binding protein (LTBP)-1. The biological role of LTBP-1 in development remains unclear. Using a polyclonal antiserum specific for LTBP-1 (Ab39) and three-dimensional collagen gel culture assay of embryonic heart, we examined the tissue distribution of LTBP-1 and its functional role during the formation of endocardial cushion tissue in the mouse embryonic heart. Mature TGFβ protein was required at the onset of the endothelial-mesenchymal transformation to initiate endocardial cushion tissue formation. Double antibody staining showed that LTBP-1 colocalized with TGFβ1 as an extracellular fibrillar structure surrounding the endocardial cushion mesenchymal cells. Immunogold electronmicroscopy showed that LTBP-1 localized to 40–100 nm extracellular fibrillar structure and 5–10-nm microfibrils. The anti–LTBP-1 antiserum (Ab39) inhibited the endothelial-mesenchymal transformation in atrio-ventricular endocardial cells cocultured with associated myocardium on a three-dimensional collagen gel lattice. This inhibitory effect was reversed by administration of mature TGFβ proteins in culture. These results suggest that LTBP-1 exists as an extracellular fibrillar structure and plays a role in the storage of TGFβ as a large latent TGFβ complex.     

Synthesis of globulins in maize embryos

The two major components of the globulin fraction in Zea mays embryos are specified by the Prot gene. Pulse-chase analysis of protein synthesis in cultured, immature embryos indicates that the smaller Prot-specific polypeptide, PROT, is derived from the larger polypeptide, PROT'. These experiments also demonstrate that PROT' is derived from a short-lived precursor polypeptide, prePROT'. The primary Prot-specific translation product, as detected by in vitro translation of immature embryo RNA, is of a lower apparent molecular weight than pre-PROT', suggesting the involvement of co- and/or post-translational modification in the production of prePROT'.     

Swift residue-screening identifies key N-glycosylated asparagines sufficient for surface expression of neuroglycoprotein Lingo-1

Advances in genomics and proteomics have generated the needs for the efficient identification of key residues for structure and function of target proteins. Here we report the utilization of a new residue-screening approach, which combines a mammalian high-throughput transient expression system with a PCR-based expression cassette, for the study of the post-translational modification. Applying this approach results in a quick identification of essential N-glycosylation sites of a heavily glycosylated neuroglycoprotein Lingo-1, which are sufficient for the support of its surface expression. These key N-glycosylated sites uniquely locate on the concave surface of the elongated arc-shape structure of the leucine-rich repeat domain. The swift residue-screening approach may provide a new strategy for structural and functional analysis.     

Current challenges in viral safety and extraneous agent testing

There are three principal elements related to viral safety in the context of immunological veterinary medicinal products: the presence of extraneous agents in either raw material used for production or in the finished product, residual pathogenicity of live viruses used as active ingredients, and incomplete inactivation of inactivated viruses used as active ingredients. Although the approach to controlling these areas of risk has not substantially changed in the recent past, a number of events, combined with advances in science and changes in the regulatory approach, make it timely to review the requirements in this area. This article reviews the major areas of change and progress with respect to the viral safety of immunological veterinary medicinal products and identifies current challenges from the perspectives of both industry and regulators.     

Transgenic mouse models of amyotrophic lateral sclerosis

The discovery of missense mutations in the gene coding for the Cu/Zn superoxide dismutase 1 (SOD1) in subsets of familial cases was rapidly followed by the generation of transgenic mice expressing various forms of SOD1 mutants. The mice overexpressing high levels of mutant SOD1 mRNAs do develop motor neuron disease but unraveling the mechanisms of pathogenesis has been very challenging. Studies with mouse lines suggest that the toxicity of mutant SOD1 is unrelated to copper-mediated catalysis but rather to propensity of a subfraction of mutant SOD1 proteins to form misfolded protein species and aggregates. However, the mechanism of toxicity of SOD1 mutants remains to be elucidated. Involvement of cytoskeletal components in ALS pathogenesis is supported by several mouse models of motor neuron disease with neurofilament abnormalities and with genetic defects in microtubule-based transport. Here, we describe how transgenic mouse models have been used for understanding pathogenic pathways of motor neuron disease and for pre-clinical drug testing.     

Climate variability and campylobacter infection: an international study

Campylobacter is among the most important agents of enteritis in developed countries. We have described the potential environmental determinants of the seasonal pattern of infection with campylobacter in Europe, Canada, Australia and New Zealand. Specifically, we investigated the role of climate variability on laboratory-confirmed cases of campylobacter infection from 15 populations. Regression analysis was used to quantify the associations between timing of seasonal peaks in infection in space and time. The short-term association between weekly weather and cases was also investigated using Poisson regression adapted for time series data. All countries in our study showed a distinct seasonality in campylobacter transmission, with many, but not all, populations showing a peak in spring. Countries with milder winters have peaks of infection earlier in the year. The timing of the peak of infection is weakly associated with high temperatures 3 months previously. Weekly variation in campylobacter infection in one region of the UK appeared to be little affected by short-term changes in weather patterns. The geographical variation in the timing of the seasonal peak suggests that climate may be a contributing factor to campylobacter transmission. The main driver of seasonality of campylobacter remains elusive and underscores the need to identify the major serotypes and routes of transmission for this disease.