A vaccine strategy utilizing a combination of three different chimeric vectors which share specific vaccine antigens

A large number of recombinant of viral and bacterial systems have been engineered as vectors to express foreign genes for vaccination and/or gene therapy. A common problem is the immune response to the vector itself. The presence of anti-vector immune responses may preclude sufficient 'priming' or immunogenicity if pre-existing immune responses are present, or they may impair optimal 'boosting' upon repeated immunization or delivery with the same vector. To circumvent this problem we developed a strategy using different chimeric vectors which share only the expression of common specific antigens desired for immunization. This approach not only has the advantage of avoiding increased anti-vector responses, but allows the use of combinations of vectors which could subsequently present the same or related antigen differently to the immune system as well as at alternative sites to induce the optimal type of immunity against the pathogen of interest.     

Modified vaccinia virus Ankara as antigen delivery system: how can we best use its potential?

Safety-tested modified vaccinia virus Ankara (MVA) has been established as a potent vector system for the development of candidate recombinant vaccines. The versatility of the vector system was recently demonstrated by the rapid production of experimental MVA vaccines for immunization against severe acute respiratory syndrome associated coronavirus. Promising results were also obtained in the delivery of Epstein-Barr virus or human cytomegalovirus antigens and from the clinical testing of MVA vectors for vaccination against immunodeficiency virus, papilloma virus, Plasmodium falciparum or melanoma. Moreover, MVA is considered to be a prime candidate vaccine for safer protection against orthopoxvirus infections. Thus, vector development to challenge dilemmas in vaccinology or immunization against poxvirus bio-threat seems possible, yet the right choice should be made for a most beneficial use.     

DNA polymerase beta overexpression stimulates the Rad51-dependent homologous recombination in mammalian cells

Overexpression of DNA polymerase β (polβ), an error-prone DNA repair enzyme, has been shown to result in mutagenesis, aneuploidy and tumorigenesis. To further investigate the molecular basis leading to cancer-associated genetic changes, we examined whether the DNA polβ could affect homologous recombination (HR). Using mammalian cells carrying an intrachromosomal recombination marker we showed that the DNA polβ overexpression increased the HR mostly by enhancing gene conversion. Concomitantly, we observed the generation of DNA strand breaks as well as a DNA polβ-dependent formation of Rad51 foci. The stimulation of HR was abolished by the coexpression of a dominant negative form of Rad51, suggesting that the Rad51 was involved in the increased HR events. The expression of different DNA polβ mutants lacking polymerase activity did not result in HR stimulation, indicating that the DNA synthesis activity of DNA polβ was related to this phenotype. These results provide new insights into the molecular mechanisms of the genetic instability observed in DNA polβ overexpressing tumour cells.     

Individualizing the aorto-radial pressure transfer function: feasibility of a model-based approach

We fitted a three-segment transmission line model for the radial-carotid/aorta pressure transfer function (TFF) in 31 controls and 30 patients with coronary artery disease using noninvasively measured (tonometry) radial and carotid artery pressures (P(car)). Except for the distal reflection coefficient (0.85 +/- 0.21 in patients vs. 0.71 +/- 0.25 in controls; P < 0.05), model parameters were not different between patients or controls. Parameters were not related to blood pressure, age, or heart rate. We further assessed a point-to-point averaged TFF (TFF(avg)) as well as upper (TFF(max)) and lower (TFF(min)) enveloping TFF. Pulse pressure (PP) and augmentation index (AIx) were derived on original and reconstructed P(car) (P(car,r)). TFF(avg) yielded closest morphological agreement between P(car) and P(car,r) (root mean square = 4.3 +/- 2.3 mmHg), and TTF(avg) best predicted PP (41.5 +/- 11.8 vs. 41.1 +/- 10.0 mmHg measured) and AIx (-0.02 +/- 0.19 vs. 0.01 +/- 0.19). PP and AIx, calculated from P(car) or P(car,r), were higher in patients than in controls, irrespectively of the TFF used. We conclude that 1) averaged TFF yield significant discrepancies between reconstructed and measured pressure waveforms and subsequent derived AIx; and 2) different TFFs seem to preserve the information in the pressure wave that discriminates between controls and patients.     

Assessment of LV diastolic filling using color M-mode Doppler echocardiography: validation in a new hydraulic model

The effect of LV properties on v _p and the E/v _p ratio remains a matter of debate. Therefore, the objective of this study is to explore – in a new hydraulic model – the individual contributions of LV relaxation, filling pressure and compliance in changes of E, v _p and E/v _p for different stages of diastolic function. A new hydraulic model, consisting of an open cylindrical LA connected to an ellipsoidal LV, is designed. E and v _p are measured for varying values of (45–60–90 ms), LV compliance (0.45–1.35 ml/mmHg) and filling pressure (3–10–30 mmHg). The results are used for predicting the evolution of E, v _p and E/v _p during different stages of diastolic function. An increase in compliance decreases E, whereas it augments v _p. v _p is less load-dependent than E. E decreases with delayed relaxation, increases for the case of pseudonormalisation, and becomes higher than the reference values during restrictive filling. The v _p value is lower for the case of delayed relaxation than for the reference situation. During pseudonormalisation, the value of v _p remains lower than the reference value but higher than the value for delayed relaxation. . v _p further decreases during restrictive filling. In conclusion, the effect of simultaneous changes in compliance and loading counterbalance changes in v _p. Therefore, under normal physiologic conditions where load and compliance are coupled, v _p is apparently load-insensitive and E/v _p increases as filling pressure increases. Moreover, in the different stages of diastolic dysfunction, due to the interference of the co-varying relaxation, the increase in E/v _p is more pronounced.     

Changes in kidney transamidinase activity during development in male and female rats

The developmental changes in the activity of kidney transamidinase in male and female rats were investigated. The activity in both sexes increased rapidly after birth, reaching adult levels at 4 days of age. After weaning, the activity in male rats remained constant, while in female rats i t declined to 60% ol that in males. Thus, transamidinase is in the neonatal cluster of enzyme differentiation.