Search results for "Acellular"

Perlecan Maintains the Integrity of Cartilage and Some Basement Membranes

1999

Perlecan is a heparan sulfate proteoglycan that is expressed in all basement membranes (BMs), in cartilage, and several other mesenchymal tissues during development. Perlecan binds growth factors and interacts with various extracellular matrix proteins and cell adhesion molecules. Homozygous mice with a null mutation in the perlecan gene exhibit normal formation of BMs. However, BMs deteriorate in regions with increased mechanical stress such as the contracting myocardium and the expanding brain vesicles showing that perlecan is crucial for maintaining BM integrity. As a consequence, small clefts are formed in the cardiac muscle leading to blood leakage into the pericardial cavity and an ar…

Role of endothelial cell stress in the pathogenesis of chronic heart failure.

2009

Endothelial cells are key modulators of diverse physiological processes, and their impaired function is a cause of numerous cardiovascular diseases. Under physiologic condition, the reactive oxygen and nitrogen mediators in endothelia lead to the signal propagation of the initial stimulus, by forming molecules with a longer half-life like hydrogen peroxide. Hydrogen peroxide is the focus of growing attention in endothelial biology, and consequently the enzymes involved in its generation and clearance are viewed as novel mediators of great importance. In particular, among peroxidases, myeloperoxidase is recognized as a key enzyme, capable of impairing intracellular NO reservoirs as well as p…

Evaluation of a novel biomarker of type XXVIII collagen formation, PRO-C28, in samples from cancer and heart failure with preserved ejection fraction…

2020

Increased turnover of extracellular matrix proteins is seen in many different diseases and is an underlying and driving feature of pathogenesis. An increased ratio of formation over degradation of extracellular matrix proteins, such as collagens, leads to accumulation of proteins in the tissues, ultimately impairing organ function. Understanding how this balance is regulated is key to providing deeper insight into high extracellular matrix turnover diseases. Type XXVIII collagen is a novel collagen with limited information available in relation to expression, tissue prevalence and clinical implication. We generated a novel, technically robust ELISA to measure a C-terminal fragment of type X…

Heat inactivation of fetal bovine serum increases protein contamination of extracellular vesicles

2022

Introduction: Extracellular vesicles (EVs) released in cell cultures are influenced by the cell culture conditions, such as the use of fetal bovine serum (FBS). FBS contains EVs and it is usually depleted of EVs by ultracentrifugation (UC) and/or heat inactivated (HI). Several studies have evaluated the effect of different UC protocols for FBS by evaluating both cells and EVs. However, less is known about the effect of HI on the cells and the released EVs. The aim of this study was therefore to evaluate the effect of HI on EV purity. Methods: To determine the effect of heat inactivation, three different protocols were applied based on different combinations of: 1) UC at 118,000 × g for 18h …

Exosomal Hsp60 in human colon cancer

2014

Digestive vacuole of Plasmodium falciparum released during erythrocyte rupture dually activates complement and coagulation.

2012

Abstract Severe Plasmodium falciparum malaria evolves through the interplay among capillary sequestration of parasitized erythrocytes, deregulated inflammatory responses, and hemostasis dysfunction. After rupture, each parasitized erythrocyte releases not only infective merozoites, but also the digestive vacuole (DV), a membrane-bounded organelle containing the malaria pigment hemozoin. In the present study, we report that the intact organelle, but not isolated hemozoin, dually activates the alternative complement and the intrinsic clotting pathway. Procoagulant activity is destroyed by phospholipase C treatment, indicating a critical role of phospholipid head groups exposed at the DV surfa…

EGF and HGF levels are increased during active HBV infection and enhance survival signaling through extracellular matrix interactions in primary huma…

2008

The hepatitis B virus (HBV) is a major causative agent of chronic liver disease and subsequent liver cirrhosis worldwide. The reduced sensitivity of virus-infected liver cells to apoptosis may play a role in the failure to remove virus-infected cells and eventually promote viral chronicity. The purpose of our study was to investigate whether survival factors induced during compensatory liver regeneration may protect hepatocytes against apoptosis. We evaluated the serum levels of hepatocyte growth factor (HGF) and epidermal growth factor (EGF) in HBV-infected patients and found significant increases in HGF and EGF in patients with active virus infection. In primary human hepatocytes we show …

Novel transmembrane topology of the hepatitis B virus envelope proteins.

1995

Abstract The small (S), middle (M) and large (L) envelope proteins of the hepatitis B virus (HBV) are initially synthesized as multispanning membrane proteins of the endoplasmic reticulum membrane. We now demonstrate that all envelope proteins synthesized in transfected cells or in a cell-free system adopt more than one transmembrane orientation. The L protein disposes its N-terminal preS domain both to the cytoplasmic and the luminal side of the membrane. This unusual topology does not depend on interaction with the viral nucleocapsid, but is preserved in secreted empty envelope particles. Pulse-chase analysis suggests a novel process of post-translational translocation leading to the non-…

Functional incorporation of green fluorescent protein into hepatitis B virus envelope particles

2004

AbstractThe envelope of hepatitis B virus (HBV), containing the L, M, and S proteins, is essential for virus entry and maturation. For direct visualization of HBV, we determined whether envelope assembly could accommodate the green fluorescent protein (GFP). While the C-terminal addition of GFP to S trans-dominant negatively inhibited empty envelope particle secretion, the N-terminal GFP fusion to S (GFP.S) was co-integrated into the envelope, giving rise to fluorescent particles. Microscopy and topogenesis analyses demonstrated that the proper intracellular distribution and folding of GFP.S, required for particle export were rescued by interprotein interactions with wild-type S. Thereby, a…

Human hepatic cell uptake of resveratrol: involvement of both passive diffusion and carrier-mediated process

2004

This work reports significant advances on the transport in hepatic cells of resveratrol, a natural polyphenol with potent protective properties. First, we describe a new simple technique to qualitatively follow resveratrol cell uptake and intracellular distribution, based on resveratrol fluorescent properties. Second, the time-course study and the quantification of (3)H-labelled resveratrol uptake have been performed using human hepatic derived cells (HepG2 tumor cells) and hepatocytes. The temperature-dependence of the kinetics of uptake as well as the cis-inhibition experiments agree with the involvement of a carrier-mediated transport in addition to passive diffusion. The decrease of pas…