Infection of mesangial cells with HIV and SIV: Identification of GPR1 as a coreceptor

Infection of mesangial cells with HIV and SIV: Identification of GPR1 as a coreceptor.BackgroundMesangial cells are an important component of the glomerulus. Dysfunction of mesangial cells is thought to be involved in the development of human immunodeficiency virus type 1 (HIV-1)-associated nephropathy (HIVAN). HIVAN is a structural renal failure frequently observed in patients with acquired immune deficiency syndrome. However, the susceptibility of mesangial cells to HIV-1 is disputable. More than ten G protein-coupled receptors, including chemokine receptors, have been shown to act as HIV-1 coreceptors that determine the susceptibilities of cells to HIV-1 strains with specific cell tropisms.MethodsWe examined the susceptibility of mesangial cells to various HIV-1, HIV type 2 (HIV-2) and simian immunodeficiency virus (SIV) strains. Expression of CD4 and HIV/SIV coreceptors was examined by Western blotting and polymerase chain reaction.ResultsMesangial cells were found to be susceptible to HIV-1 variant and mutants that infect brain-derived cells, but highly resistant to T-tropic (X4), M-tropic (R5) or dual-tropic (X4R5) HIV-1 strains. In addition, mesangial cells were also susceptible to HIV-2 and SIV strains that infect the brain-derived cells. Among HIV/SIV coreceptors we tested, the expression of GPR1 mRNA was detected in mesangial cells. Expression of CD4 mRNA and protein was also detected in them. Mesangial cells and GPR1-transduced CD4-positive cells showed similar susceptibilities to the HIV-1 variant and mutants and HIV-2 and SIV strains.ConclusionsCD4 and GPR1 mRNAs were detected in mesangial cells. Mesangial cells were susceptible to HIV/SIV strains that use GPR1 as a coreceptor. Our findings suggest that an orphan G protein-coupled receptor, GPR1, is a coreceptor expressed in mesangial cells. It remains to be investigated whether the interaction of mesangial cells with specific HIV-1 strains through GPR1 plays a role in the development of HIVAN

The impacts of a fliD mutation on the biofilm formation of Helicobacter pylori

AbstractObjectiveTo investigate the impact of the fliD gene on the biofilm formation of Helicobacter pylori (H. pylori).MethodsH. pylori fliD mutant was constructed using inverse PCR mutagenesis. The mobility of the bacteria and its adhesion ability to human epithelial cells were assessed using a motility assay and a fluorescein isothiocyanate staining adhesion assay, respectively. The formation of biofilm was evaluated using a pellicle assay and a crystal violet staining assay. The cyto-architecture of the biofilm was documented with scanning electron microscopy.ResultsIt was found that there was no significant difference in the levels of bacterial adhesion and the biofilm formation between the wild-type ATCC 43504 and the fliD mutant. Apart from a poor motility, the fliD mutant had a slightly delayed formation of its biofilm and an incomplete cyto-architecture of its biofilm. The bacterial cells residing in the biofilm of the fliD mutant showed a loose accumulation with less apparent cross-linking fibrils. Most of the mutant cells had truncated flagella.ConclusionsThis study provides the preliminary evidences that fliD potentially regulates biofilm formation and is required for the motility of H. pylori. Further studies need to be performed in order to develop fliD as a novel target for vaccine or antimicrobial agent in future

Insertion and hairpin formation of membrane proteins: a Monte Carlo study

Some particular effects of a lipid membrane on the partitioning and the concomitant folding processes of model proteins have been investigated using Monte Carlo methods. It is observed that orientational order and lateral density fluctuations of the lipid matrix stabilize the orientation of helical proteins and induce a tendency of spontaneous formation of helical hairpins for helices longer than the width of the membrane. The lateral compression of the lipids on a hairpin leads to the extrusion of a loop at the trans side of the membrane. The stability of the hairpin can be increased by the design of appropriate groups of hydrophilic and hydrophobic residues at the extruded loop. It is shown that in the absence of lipids the orientation of proteins is not stable and the formation of hairpins is absent. Some analogies between the formation of helical hairpins in membranes and the formation of hairpins in polymer liquid crystals are discussed. The simulations indicate that the insertion process follows a well-defined pattern of kinetic steps

Galbladder perforation: The importance of standardised treatment algorithms

Von H. Barfo

Extensions of Standard Weak Bisimulation Machinery: Finite-state General Processes, Refinable Actions, Maximal-progress and Time

AbstractWe present our work on extending the standard machinery for weak bisimulation to deal with: finite-state processes of calculi with a full signature, including static operators like parallel; semantic action refinement and ST bisimulation; maximal-progress, i.e. priority of standard actions over unprioritized actions; representation of time: discrete real-time and Markovian stochastic time. For every such topic we show that it is possible to resort simply to weak bisimulation and that we can exploit this to obtain, via modifications to the standard machinery: finite-stateness of semantic models when static operators are not replicable by recursion, as for CCS with the standard semantics, thus yielding decidability of equivalence; structural operational semantics for terms; a complete axiomatization for finite-state processes via a modification of the standard theory of standard equation sets and of the normal-form derivation procedure

Characterization of mouse switch variant antibodies by matrix-assisted laser desorption ionization mass spectrometry and electrospray ionization mass spectrometry

The amino acid sequences of mouse monoclonal antibodies have been characterized completely by mass spectrometry. Antibodies used in the present study were derived from mouse switch variant cell lines that produce four kinds of immunoglobulin Gs (IgGs). The amino acid sequences of these antibodies had not been estimated from the corresponding DNA sequence, so the sequences of IgGs derived from other strains were used as references in this study. Intra- and interchain disulfide bonds of the IgGs were reduced and carboxymethylated and the products were subjected to proteolytic digestion. The existence of N-linked oligosaccharides also was taken into account. The capabilities and limitations of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and capillary liquid chromatography-electrospray ionization mass spectrometry are discussed in the structural characterization of the antibodies. Based on our results, allotypes of the antibodies examined are discussed. This study shows that amino acid sequences of proteins, such as IgG, can be investigated without information about the corresponding DNA sequence if appropriate reference sequences derived from other strains can be used

Probing the outer vestibule of a sodium channel voltage sensor

The second and third basic residues of the S4 segment of domain 4 (D4:R2 and D4:R3) of the human skeletal muscle Na+ channel are known to be translocated from a cytoplasmic to an extracellular position during depolarization. Accessibilities of individual S4 residues were assayed by alteration of inactivation kinetics during modification of cysteine mutants by hydrophilic methanethiosulfonate reagents. The voltage dependences of the reaction rates are identical for extracellular application of cationic methanethiosulfonate-ethyltrimethylammonium (MTSET) and anionic methanethiosulfonate-ethylsulfonate (MTSES), suggesting that D4:R3C is situated outside the membrane electric field at depolarized voltages. The absolute rate of R3C modification is 281-fold greater for MTSET than for MTSES, however, suggesting that at depolarized voltages this S4 thiol resides in a negatively charged hydrophilic crevice. The two hydrophobic residues between D4:R2C and D4:R3C in the primary sequence (L1452 and A1453) are not externally exposed at any voltage. An alpha-helical representation of D4/S4 shows that the basic residues D4:R2 and D4:R3 are on the face opposite that of L1452 and A1453. We propose that in the depolarized conformation, the hydrophobic face of this portion of D4/S4 remains in contact with a hydrophobic region of the extracellular vestibule of the S4 channel

TCT-669 Very Low Intravenous Contrast Dose (20 cc) Computed Tomographic Angiography Protocol for Pre-Procedural Assessment of the Aortic Annulus Prior to Transcatheter Aortic Valve Replacement: Validation by 3-Dimensional Transesophageal Echocardiography

Von Dr. Fr. Dietric