The Protein Tyrosine Phosphatase Receptor Delta Regulates Developmental Neurogenesis

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High hydrostatic pressure in cancer immunotherapy and biomedicine

High hydrostatic pressure (HHP) has been known to affect biological systems for >100?years. In this review, we describe the technology of HHP and its effect macromolecules and physiology of eukaryotic cells. We discuss the use of HHP in cancer immunotherapy to kill tumor cells for generation of whole cell and dendritic cell-based vaccines. We further summarize the current use and perspectives of HHP application in biomedicine, specifically in orthopedic surgery and for the viral, microbial and protozoan inactivation to develop vaccines against infectious diseases.     

Rat liver DNA polymerase-beta: thermal inactivation of RNA- and DNA-dependent activities

Purified DNA polymerase-beta from rat liver was exposed to thermal inactivation and the remaining activities were then measured either with a hybrid template such as poly(A).(dT)12-18 (R-activity) or with a DNA template such as poly(dA).(dT)12-18 (D-activity). Time course of inhibition of R- and D-activities were identical. Neither activity was protected when the thermal treatment was performed in the presence of the template or dNTPs.     

Control of the risk of human toxoplasmosis transmitted by meat

One-third of the human world population is infected with the protozoan parasite Toxoplasma gondii. Recent calculations of the disease burden of toxoplasmosis rank this foodborne disease at the same level as salmonellosis or campylobacteriosis. The high disease burden in combination with disappointing results of the currently available treatment options have led to a plea for more effective prevention. In this review we describe Toxoplasma as a hazard associated with the consumption of undercooked meat or meat products and provide an analysis of the various options to control the risk of human toxoplasmosis via this source. Monitoring and surveillance programs may be implemented for pre-harvest control of Toxoplasma infection of farm animals, with the reduction of environmental oocyst load as the most important milestone. Alternatively, Toxoplasma safe meat can be obtained through simple post-harvest decontamination procedures, whereby freezing the meat may currently be the best option, although new technologies using irradiation or high-pressure treatment may offer promising alternatives. Influence of culture, religion and food handling customs may predispose a certain type of meat as an important source of infection, indicating that prevention needs to be tailored according to social habits in different regions in the world. The rationale for more stringent control measures to prevent toxoplasmosis both from disease and economic points of view is emphasized.     

Dynactin is essential for growth cone advance

Dynactin is a multi-subunit complex that serves as a critical cofactor of the microtubule motor cytoplasmic dynein. We previously identified dynactin in the nerve growth cone. However, the function of dynactin in the growth cone is still unclear. Here we show that dynactin in the growth cone is required for constant forward movement of the growth cone. Chromophore-assisted laser inactivation (CALI) of dynamitin, a dynactin subunit, within the growth cone markedly decreases the rate of growth cone advance. CALI of dynamitin in vitro dissociates another dynactin subunit, p150^Glued, from dynamitin. These results indicate that dynactin, especially the interaction between dynamitin and p150^Glued, plays an essential role in growth cone advance.     

High-pressure inactivation of dried microorganisms

Dried microorganisms are particularly resistant to high hydrostatic pressure effects. In this study, the survival of Saccharomyces cerevisiae was studied under pressure applied in different ways. Original processes and devices were purposely developed in our laboratory for long-term pressurization. Dried and wet yeast powders were submitted to high-pressure treatments (100-150 MPa for 24-144 h at 25 degrees C) through liquid media or inert gas. These powders were also pressurized after being vacuum-packed. In the case of wet yeasts, the pressurization procedure had little influence on the inactivation rate. In this case, inactivations were mainly due to hydrostatic pressure effects. Conversely, in the case of dried yeasts, inactivation was highly dependent on the treatment scheme. No mortality was observed when dried cells were pressurized in a non-aqueous liquid medium, but when nitrogen gas was used as the pressure-transmitting fluid, the inactivation rate was found to be between 1.5 and 2 log for the same pressure level and holding time. Several hypotheses were formulated to explain this phenomenon: the thermal effects induced by the pressure variations, the drying resulting from the gas pressure release and the sorption and desorption of the gas in cells. The highest inactivation rates were obtained with vacuum-packed dried yeasts. In this case, cell death occurred during the pressurization step and was induced by shear forces. Our results show that the mechanisms at the origin of cell death under pressure are strongly dependent on the nature of the pressure-transmitting medium and the hydration of microorganisms.     

Evaluation of microfluidics reactor technology on the kinetics of virus inactivation

Mammalian cell lines constitute an important part in the manufacture of therapeutic proteins. However, their susceptibility to virus contamination is a potential risk to patient safety and productivity, and has led to the development of a repertoire of virus inactivation techniques. From a process development viewpoint, the challenge is to demonstrate the required log reduction in virus content without a significant loss in product titer or quality. The balance between the two is dictated by the kinetics of virus inactivation and protein degradation, both of which are critically affected by process parameters. In this study we describe a commercially available microchannel reactor (MCR) and demonstrate how it can be used to evaluate the impact of temperature on the kinetics of virus inactivation and protein product degradation. Virus spiking experiments are reported using Xenotropic Murine Leukemia Virus and REOvirus, into buffers in the absence and presence of a therapeutic protein currently under development at Lilly. The results demonstrate that the MCR is an ideal platform for evaluation of fast reactive systems and reactions that are particularly sensitive to small changes to process conditions. These conditions include heat inactivation of a virus in a mammalian cell culture process stream used in the manufacture of therapeutic proteins and antibodies.     

Kinetics of thermal aggregation of glycogen phosphorylase b from rabbit skeletal muscle: mechanism of protective action of alpha-crystallin

The kinetics of thermal aggregation of glycogen phosphorylase b (Phb) from rabbit skeletal muscle have been studied by dynamic light scattering (0.08M Hepes, pH 6.8, containing 0.1M NaCl; 48 degrees C). The hydrodynamic radius of the start aggregates determined from the initial linear parts of the dependences of the hydrodynamic radius (R(h)) on time was found to be 16.7 +/- 1.0 nm. At rather high values of time, the R(h) value for the protein aggregates becomes proportional to t(1/1.8) = t(0.56) suggesting that the aggregation process proceeds in the regime of diffusion-limited cluster-cluster aggregation. In the presence of alpha-crystallin, a protein possessing the chaperone-like activity, the process of protein aggregation switches to the regime of reaction-limited cluster-cluster aggregation as indicated by the exponential dependence of the R(h) value on time. It was shown that the addition of alpha-crystallin raises the rate of thermal inactivation of Phb. These data in combination with the results of the study of interaction of Phb with alpha-crystallin by analytical ultracentrifugation suggest that alpha-crystallin interacts with the intermediates of unfolding of the Phb molecule.     

Structural studies of the O-antigens of Yersinia pseudotuberculosis O:2a and mutants thereof with impaired 6-deoxy-D-manno-heptose biosynthesis pathway

The full structure of the long- and short-chain O-antigen of Yersinia pseudotuberculosis O:2a containing two uncommon deoxy sugars, abequose and 6-deoxy-d-manno-heptose (6dmanHep), was established, for the first time, by sugar analysis, NMR spectroscopy, and high-resolution ESIMS. Similar structural studies were also performed on two O:2a mutants with single disruption of 6dmanHep synthesis pathway genes each, which synthesize modified long-chain (dmhA mutant) and short-chain (both dmhA and dmhB mutants) O-antigens with 6dmanHep replaced by its putative biosynthetic precursor, D-glycero-D-manno-heptose.