A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

Influence of Pre-, Intra- and Post-Operative Parameters of Donor Liver on the Outcome of Isolated Human Hepatocytes

The aim of the present study was to analyse, retrospectively on a large panel of patients (149), the influence of the donor liver characteristics on the outcome of human hepatocyte isolation obtained from resected liver biopsies from surgical waste after hepatectomy. Among the pre-operative parameters, the type of disease, age and sex of the patient, previous chemotherapy, alcohol or tobacco consumption did not affect the yield, viability, attachment rate and function of the isolated human hepatocytes. Pre-operative biological and anatomopathological data indicated that, while mild steatosis (≤10% steatotic hepatocytes) did also not affect the outcome of hepatocyte isolation, stronger steatosis (>10% steatotic hepatocytes) tended to decrease hepatocyte yield. Cholestasis, as assessed by γ-glutamyl transferase serum values, significantly negatively correlated with the percentage of digested liver and the yield of viable cells. Intra-operative clamping time, that is, warm ischaemia, longer than 30 min was found to decrease both the percentage of digested liver and cell yield. Among the post-operative parameters, the percentage of digested liver decreased when biopsy weights were higher than 100 g, the use of glue tended to increase both the percentage of digested tissue and the yield of viable cells. In conclusion, human diseased livers appear to be a valuable source of isolated functional human hepatocytes. We recommend, for an optimal isolation, to use liver biopsies weighing less than 100 g, to glue the section surfaces of the biopsies and to avoid the use of moderate steatotic livers (>10% steatotic hepatocytes) and cholestatic livers, as well as livers undergoing warm ischaemia or clamping during resection due to the decrease in cell yield. This revised version was published online in July 2006 with corrections to the Cover Date.     

A mathematical model for elongation of a peptide chain

A mathematical model is presented for the steps in the elongation process, and the steady-state elongation rate as a function of the amino acid concentrations is found. In addition, the reset sub-process of the elongation process is modeled. The rate of elongation of peptide chains is found to be a function of the concentration of the amino acid to be bound and the concentration of all other amino acids. In addition, the overall elongation rate depends on the concentrations of elongation factors.     

Continuous rhamnolipid production with integrated product removal by foam fractionation and magnetic separation of immobilized Pseudomonas aeruginosa

Increasing interest in biological surfactants has led to intensified research directed at more cost-efficient production of biosurfactants, relative to traditional surface-active components based on petrochemical feedstocks. This publication will focus on a new integrated process for continuous rhamnolipid (RL) production. RL was synthesized by Pseudomonas aeruginosa DSM 2874 and was continuously removed in situ by foam fractionation. To prevent loss of the biocatalyst through foaming, bacteria were entrapped in magnetic alginate beads. Immobilizates were retained from the foam by high-gradient magnetic separation and back-flushed in the bioreactor at constant intervals. It was demonstrated that continuous RL production in a 10-L bioreactor over several cycles with intermediate growth periods is feasible. Complete separation of RLs from the production medium with an average enrichment ratio of 15 in the collapsed foam was demonstrated, yielding a final RL amount of 70 g after four production cycles.     

Sonic hedgehog myocardial gene therapy: tissue repair through transient reconstitution of embryonic signaling

Sonic hedgehog (Shh) is a crucial regulator of organ development during embryogenesis. We investigated whether intramyocardial gene transfer of naked DNA encoding human Shh (phShh) could promote a favorable effect on recovery from acute and chronic myocardial ischemia in adult animals, not only by promoting neovascularization, but by broader effects, consistent with the role of this morphogen in embryogenesis. After Shh gene transfer, the hedgehog pathway was upregulated in mammalian fibroblasts and cardiomyocytes. This resulted in preservation of left ventricular function in both acute and chronic myocardial ischemia by enhanced neovascularization, and reduced fibrosis and cardiac apoptosis. Shh gene transfer also enhanced the contribution of bone marrow-derived endothelial progenitor cells to myocardial neovascularization. These data suggest that Shh gene therapy may have considerable therapeutic potential in individuals with acute and chronic myocardial ischemia by triggering expression of multiple trophic factors and engendering tissue repair in the adult heart.     

Kinetic and mechanistic considerations in the gelation of genipin-crosslinked gelatin

The gelling properties (gel time (t_gel) and gel strength) of a 10% (w/w) gelatin sol were investigated as a function of genipin (GP) concentration (0–15 mM) and temperature (25–55 °C) to discern mechanisms and optimal conditions for fixation. Gel time increased with increasing temperature, reached a maximum, and then declined as temperature was raised further. By contrast, network strength data followed the opposite trend. From the thermal behavior of t_gel and network strength, it was inferred that gelation in the low-temperature regime was dominated by hydrogen bonding, while in the high-temperature regime it was dominated by covalent crosslinking. At higher temperatures, crosslinking was described by an Arrhenius rate law expression, with activation energies between 63.2 and 67.8 kJ/mol, depending on GP concentration. In the low temperature regime, an Arrhenius plot resulted in negative activation energies of −75.8 and −64.4 kJ/mol in the presence of 10 and 15 mM GP, respectively. With an increase in both GP concentration and temperature, the gelatin network gradually shifted from being dominated by hydrogen bonds (physical crosslinks) to covalent crosslinking (chemical crosslinks).     

Adaptation of Pseudomonas aeruginosa ATCC 15442 to didecyldimethylammonium bromide induces changes in membrane fatty acid composition and in resistance of cells

The role of membrane fatty acid composition in the resistance of Pseudomonas aeruginosa ATCC 15442 to the bactericidal activity of didecyldimethyl ammonium bromide (DDAB) was investigated. In this study, the strain was sub-cultured in a medium with increasing DDAB concentrations. After adaptation, Ps. aeruginosa was able to grow until the DDAB concentration in the medium was about five times greater than the Minimal Inhibitory Concentration. Resistance of cells to the bactericidal activity of DDAB also increased gradually during adaptation. This resistance was dependent on the presence of the biocide, as it quickly decreased when the cells were transferred to medium without biocide. Adapted cells showed changes in membrane fatty acid composition. The modifications mainly affected lauric, beta-hydroxylauric and palmitic acids, and they underlined the implication of the membranes in the cell response to the presence of the biocide. Simple linear regression analysis showed that the membrane fatty acid composition of Ps. aeruginosa played an important part in the resistance mechanisms of cells to the bactericidal activity of DDAB.