3D Texture Analysis Reveals Imperceptible MRI Textural Alterations in the Thalamus and Putamen in Progressive Myoclonic Epilepsy Type 1, EPM1

Progressive myoclonic epilepsy type 1 (EPM1) is an autosomal recessively inherited neurodegenerative disorder characterized by young onset age, myoclonus and tonic-clonic epileptic seizures. At the time of diagnosis, the visual assessment of the brain MRI is usually normal, with no major changes found later. Therefore, we utilized texture analysis (TA) to characterize and classify the underlying properties of the affected brain tissue by means of 3D texture features. Sixteen genetically verified patients with EPM1 and 16 healthy controls were included in the study. TA was performed upon 3D volumes of interest that were placed bilaterally in the thalamus, amygdala, hippocampus, caudate nucleus and putamen. Compared to the healthy controls, EPM1 patients had significant textural differences especially in the thalamus and right putamen. The most significantly differing texture features included parameters that measure the complexity and heterogeneity of the tissue, such as the co-occurrence matrix-based entropy and angular second moment, and also the run-length matrix-based parameters of gray-level non-uniformity, short run emphasis and long run emphasis. This study demonstrates the usability of 3D TA for extracting additional information from MR images. Textural alterations which suggest complex, coarse and heterogeneous appearance were found bilaterally in the thalamus, supporting the previous literature on thalamic pathology in EPM1. The observed putamenal involvement is a novel finding. Our results encourage further studies on the clinical applications, feasibility, reproducibility and reliability of 3D TA.     

Proteolytic systems of lactic acid bacteria

Lactic acid bacteria (LAB) have a very long history of use in the manufacturing processes of fermented foods and a great deal of effort was made to investigate and manipulate the role of LAB in these processes. Today, the diverse group of LAB includes species that are among the best-studied microorganisms and proteolysis is one of the particular physiological traits of LAB of which detailed knowledge was obtained. The proteolytic system involved in casein utilization provides cells with essential amino acids during growth in milk and is also of industrial importance due to its contribution to the development of the organoleptic properties of fermented milk products. For the most extensively studied LAB, Lactococcus lactis, a model for casein proteolysis, transport, peptidolysis, and regulation thereof is now established. In addition to nutrient processing, cellular proteolysis plays a critical role in polypeptide quality control and in many regulatory circuits by keeping basal levels of regulatory proteins low and removing them when they are no longer needed. As part of the industrial processes, LAB are challenged by various stress conditions that are likely to affect metabolic activities, including proteolysis. While environmental stress responses of LAB have received increasing interest in recent years, our current knowledge on stress-related proteolysis in LAB is almost exclusively based on studies on L. lactis. This review provides the current status in the research of proteolytic systems of LAB with industrial relevance.     

Echovirus 1 infection depends on biogenesis of novel multivesicular bodies

Non-enveloped picornavirus echovirus 1 (EV1) clusters its receptor α2β1 integrin and causes their internalization and accumulation in α2β1 integrin enriched multivesicular bodies (α2-MVBs). Our results here show that these α2-MVBs are distinct from acidic late endosomes/lysosomes by several criteria: (i) live intra-endosomal pH measurements show that α2-MVBs are not acidic, (ii) they are not positive for the late endosomal marker LBPA or Dil-LDL internalized to lysosomes, and (iii) simultaneous stimulation of epidermal growth factor receptor (EGFR) and α2β1 integrin clustering leads to their accumulation in separate endosomes. EGFR showed downregulation between 15 min and 2 h, whereas accumulation of α2β1 integrin/EV1 led to an increase of integrin fluorescence in cytoplasmic vesicles further suggesting that EV1 pathway is separate from the lysosomal downregulation pathway. In addition, the results demonstrate the involvement of ESCRTs in the biogenesis of α2-MVBs. Overexpression of dominant-negative form of VPS4 inhibited biogenesis of α2-MVBs and efficiently prevented EV1 infection. Furthermore, α2-MVBs were positive for some members of ESCRTs such as Hrs, VPS37A and VPS24 and the siRNA treatment of TSG101, VPS37A and VPS24 inhibited EV1 infection. Our results show that the non-enveloped EV1 depends on biogenesis of novel multivesicular structures for successful infection.     

Occurrence of proteolytic inhibitors in various tissues of barley

Summary The three groups of proteolytic inhibitors present in resting barley grains, namely, trypsin inhibitors, Aspergillus-proteinase inhibitors, and inhibitors of endogenous proteinases, occur in both the embryo and the two endosperm tissues. There are pronounced quantitative differences, however. The three inhibitor activities in the embryo are, respectively, 6-, 0.1-, and 6-fold of those in the endosperm.During germination at 20° all inhibitor activities disappear from the endosperms in 4–5 days. Young rootlets and coleoptiles contain inhibitors of trypsin and Aspergillus proteinase, but these disappear after 4–5 days' germination. However, the trypsin inhibitor content per seedlings remains roughly constant through the whole period. The Aspergillus-proteinase inhibitors, in contrast, exhibit a pronounced increase of activity per seedling.No inhibitor activities were detected in leaves and roots at later stages of growth.The trypsin inhibitor which we have earlier purified from resting grains occurs exclusively in the two endospermal tissues and is immunologically entirely different from the trypsin inhibitors present in embryos and young seedlings.     

RhoE function is regulated by ROCK I-mediated phosphorylation

The Rho GTPase family member RhoE regulates actin filaments partly by binding to and inhibiting ROCK I, a serine/threonine kinase that induces actomyosin contractility. Here, we show that ROCK I can phosphorylate multiple residues on RhoE in vitro. In cells, ROCK I-phosphorylated RhoE localizes in the cytosol, whereas unphosphorylated RhoE is primarily associated with membranes. Phosphorylation has no effect on RhoE binding to ROCK I, but instead increases RhoE protein stability. Using phospho-specific antibodies, we show that ROCK phosphorylates endogenous RhoE at serine 11 upon cell stimulation with platelet-derived growth factor, and that this phosphorylation requires an active protein kinase C signalling pathway. In addition, we demonstrate that phosphorylation of RhoE correlates with its activity in inducing stress fibre disruption and inhibiting Ras-induced transformation. This is the first demonstration of an endogenous Rho family member being phosphorylated in vivo and indicates that phosphorylation is an important mechanism to control the stability and function of this GTPase-deficient Rho protein.     

Dynamics of two separate but linked HIV-1 CRF01_AE outbreaks among injection drug users in Stockholm, Sweden, and Helsinki, Finland

Detailed phylogenetic analyses were performed to characterize an HIV-1 outbreak among injection drug users (IDUs) in Stockholm, Sweden, in 2006. This study investigated the source and dynamics of HIV-1 spread during the outbreak as well as associated demographic and clinical factors. Seventy Swedish IDUs diagnosed during 2004 to 2007 were studied. Demographic, clinical, and laboratory data were collected, and the V3 region of the HIV-1 envelope gene was sequenced to allow detailed phylogenetic analyses. The results showed that the Stockholm outbreak was caused by a CRF01_AE variant imported from Helsinki, Finland, around 2003, which was quiescent until the outbreak started in 2006. Local Swedish subtype B variants continued to spread at a lower rate. The number of new CRF01_AE cases over a rooted phylogenetic tree accurately reflected the transmission dynamics and showed a temporary increase, by a factor of 12, in HIV incidence during the outbreak. Virus levels were similar in CRF01_AE and subtype B infections, arguing against differences in contagiousness. Similarly, there were no major differences in other baseline characteristics. Instead, the outbreak in Stockholm (and Helsinki) was best explained by an introduction of HIV into a standing network of previously uninfected IDUs. The combination of phylogenetics and epidemiological data creates a powerful tool for investigating outbreaks of HIV and other infectious diseases that could improve surveillance and prevention.     

Vpu and Tsg101 regulate intracellular targeting of the human immunodeficiency virus type 1 core protein precursor Pr55gag

Assembly of human immunodeficiency virus type 1 (HIV-1) is directed by the viral core protein Pr55gag. Depending on the cell type, Pr55gag accumulates either at the plasma membrane or on late endosomes/multivesicular bodies. Intracellular localization of Pr55gag determines the site of virus assembly, but molecular mechanisms that define cell surface or endosomal targeting of Pr55gag are poorly characterized. We have analyzed targeting of newly synthesized Pr55gag in HeLa H1 cells by pulse-chase studies and subcellular fractionations. Our results indicated that Pr55gag was inserted into the plasma membrane and, when coexpressed with the viral accessory protein Vpu, Pr55gag remained at the plasma membrane and virions assembled at this site. In contrast, Pr55gag expressed in the absence of Vpu was initially inserted into the plasma membrane, but subsequently endocytosed, and virus assembly was partially shifted to internal membranes. This endocytosis of Pr55gag required the host protein Tsg101. These results identified a previously unknown role for Vpu and Tsg101 as regulators for the endocytic uptake of Pr55gag and suggested that the site of HIV-1 assembly is determined by factors that regulate the endocytosis of Pr55gag.