Induction of multi-antigen multi-stage immune responses against Plasmodium falciparum in rhesus monkeys, in the absence of antigen interference, with heterologous DNA prime/poxvirus boost immunization.

The present study has evaluated the immunogenicity of single or multiple Plasmodium falciparum (Pf) antigens administered in a DNA prime/poxvirus boost regimen with or without the poloxamer CRL1005 in rhesus monkeys. Animals were primed with PfCSP plasmid DNA or a mixture of PfCSP, PfSSP2/TRAP, PfLSA1, PfAMA1 and PfMSP1-42 (CSLAM) DNA vaccines in PBS or formulated with CRL1005, and subsequently boosted with ALVAC-Pf7, a canarypox virus expressing the CSLAM antigens. Cell-mediated immune responses were evaluated by IFN-gamma ELIspot and intracellular cytokine staining, using recombinant proteins and overlapping synthetic peptides. Antigen-specific and parasite-specific antibody responses were evaluated by ELISA and IFAT, respectively. Immune responses to all components of the multi-antigen mixture were demonstrated following immunization with either DNA/PBS or DNA/CRL1005, and no antigen interference was observed in animals receiving CSLAM as compared to PfCSP alone. These data support the down-selection of the CSLAM antigen combination. CRL1005 formulation had no apparent effect on vaccine-induced T cell or antibody responses, either before or after viral boost. In high responder monkeys, CD4+IL-2+ responses were more predominant than CD8+ T cell responses. Furthermore, CD8+ IFN-gamma responses were detected only in the presence of detectable CD4+ T cell responses. Overall, this study demonstrates the potential for multivalent Pf vaccines based on rational antigen selection and combination, and suggests that further formulation development to increase the immunogenicity of DNA encoded antigens is warranted.

Consequences of brief exposure to high concentrations of carbon monoxide in conscious rats.

Exposure to high-concentration carbon monoxide (CO) is of concern in military operations. Experimentally, the physiologic manifestations of a brief exposure to elevated levels of CO have not been fully described. This study investigated the development of acute CO poisoning in conscious male Sprague-Dawley rats (220-380 g). Animals were randomly grouped (n = 6) and exposed to either air or 1 of 6 CO concentrations (1000, 3000, 6000, 10,000, 12,000, or 24,000 ppm) in a continuous air/CO dynamic exposure chamber for 5 min. Respiration was recorded prior to and during exposures. Mixed blood carboxyhemoglobin (COHb) and pH were measured before and immediately after exposure. Before exposure the mean baselines of respiratory minute volumes (RMVs) were 312.6 +/- 43.9, 275.2 +/- 40.8, and 302.3 +/- 39.1 ml/min for the 10,000, 12,000 and 24,000 ppm groups, respectively. In the last minute of exposure RMVs were 118.9 +/- 23.7, 62.1 +/- 10.4, and 22.0 +/- 15.1% (p < .05) of their mean baselines in these 3 groups, respectively. Immediately after exposure, blood COHb saturations were elevated to 60.16, 63.42, and 69.37%, and blood pH levels were reduced to 7.43 +/- 0.09, 7.25 +/- 0.05, and 7.13 +/- 0.04 in the 3 groups, respectively. Mortality during exposure was 1/12 in the 12,000 ppm group and 4/12 in the 24,000 ppm group. Deaths occurred close to the end of 5 min exposure. In each animal that died by exposure, pH was <6.87 and COHb saturation was >82%. Blood pH was unaltered and no death occurred in rats exposed to CO at concentrations <6000 ppm, although COHb saturations were elevated to 14.52, 29.94, and 57.24% in the 1000, 3000, and 6000 ppm groups, respectively. These results suggest that brief exposure to CO at concentrations <10,000 ppm may produce some significant physiological changes. However, exposure to CO at concentrations >10,000 ppm for brief periods as short as 5 min may change RMV, resulting in acute respiratory failure, acidemia, and even death.

Non-linear effects of cycloheximide in glutamate-treated cultured rat cerebellar neurons.

Multiple cell types and organisms across a wide array of phyla and a variety of toxins demonstrate non-linear dose responses to low-level chemical exposures with high doses inhibiting cellular function and low doses stimulating function. We tested whether such non-linear responses to low and ultra-low dose N-methyl-D-aspartate (NMDA), 1-methyl-4-phenylpyridinium (MPP+) or cycloheximide moderated toxic glutamate exposure in cultured cerebellar granule cells. Neurons were incubated over 72 h with successive NMDA, MPP+ iodide or cycloheximide additions producing specified low (10(-5), 10(-7), 10(-9), 10(-11), and 10(-13) M) and ultra-low (10(-27),10(-29), 10(-63), and 10(-65) M) concentrations. Subsequently these neuronal cells were exposed to a 50% excitotoxic concentration of glutamate for 24 h. Neuronal viability was significantly reduced in neurons treated with micromolar (10(-5) M) cycloheximide whereas viability was enhanced in neurons treated with an ultra-low dose exposure of 10(-27) M cycloheximide. Neither NMDA nor MPP+ elicited harmful or protective responses. This is the first report demonstrating non-linear dose-response effects of cycloheximide in low and ultra-low concentration ranges.

Physical and thermal properties of blood storage bags: implications for shipping frozen components on dry ice.

BACKGROUND: Frozen blood components are shipped on dry ice. The lower temperature (-70 degrees C in contrast to usual storage at -30 degrees C) and shipping conditions may cause a rent in the storage bag, breaking sterility and rendering the unit useless. The rate of loss can reach 50 to 80 percent. To identify those bags with lower probability of breaking during shipment, the thermal and physical properties of blood storage bags were examined. STUDY DESIGN AND METHODS: Blood storage bags were obtained from several manufacturers and were of the following compositions: PVC with citrate, di-2-ethylhexylphthalate (DEHP), or tri-2-ethylhexyl-tri-mellitate (TEHTM) plasticizer; polyolefin (PO); poly(ethylene-co-vinyl acetate) (EVA); or fluorinated polyethylene propylene (FEP). The glass transition temperature (Tg) of each storage bag was determined. Bag thickness and measures of material strength (tensile modulus [MT] and time to achieve 0.5 percent strain [T0.5%]) were evaluated. M(T) and T0.5% measurements were made at 25 and -70 degrees C. Response to applied force at -70 degrees C was measured using an impact testing device and a drop test. RESULTS: The Tg of the bags fell into two groups: 70 to 105 degrees C (PO, FEP) and -50 to -17 degrees C (PVC with plasticizer, EVA). Bag thickness ranged from 0.14 to 0.41 mm. Compared to other materials, the ratios of M(T) and T0.5% for PVC bags were increased (p < or = 0.001) indicating that structural changes for PVC were more pronounced upon cooling from 25 to -70 degrees C. Bags containing EVA were more shock resistant, resulting in the lowest rate of breakage (10% breakage) when compared with PO (60% breakage, p = 0.0573) or PVC (100% breakage, p = 0.0001). CONCLUSIONS: Blood storage bags made of EVA appear better suited for shipping frozen blood components on dry ice and are cost-effective replacements for PVC bags. For the identification of blood storage bags meeting specific storage requirements, physical and thermal analyses of blood storage bags may be useful and remove empiricism from the process.