Liquid-chromatographic profiling of Saponinum album (Merck)

Saponinum album (Merck) is a complex composite of triterpene saponins. It was shown that Saponinum album (Merck) dramatically enhances the toxicity of the N-glycosylase saporin from the seeds of Saponaria officinalis L. as well as the toxicity of a saporin based anti-tumor toxin. This study was intended to chromatographically profile the saponins present in Saponinum album (Merck) in order to identify saponins that determine the cytotoxicity enhancing properties of Saponinum album (Merck) on saporin. For this purpose a liquid-chromatographic profiling (HPLC) followed by ESI-TOF-MS analysis and evaluation of cytotoxicity enhancer effects of saponins from Saponinum album (Merck) was performed. This is the first study describing a liquid-chromatographic profiling of saponins from Saponinum album (Merck). Ten different saponins were isolated. There was a lot of variation observed in the cytotoxicity enhancing properties of different isolated saponins, 8 out of 10 isolated saponins showed an enhancer effect on the toxicity of saporin. Based on these results it was concluded that the cytotoxicity enhancer effect of Saponinum album (Merck) is not attributable to a single, activity determining saponin.

Predictors of early nasal CPAP failure and effects of various intubation criteria on the rate of mechanical ventilation in preterm infants of <29 weeks gestational age

INTRODUCTION

Delivery room management using early nasal continuous positive airway pressure (nCPAP) may delay surfactant therapy.

OBJECTIVE

To identify factors associated with early nCPAP failure and effects of various intubation criteria on rate and time of intubation.

DESIGN

Retrospective analysis of the first 48 h in infants of 23-28 weeks gestational age (GA) treated with sustained inflations followed by early nCPAP.

RESULTS

Of 225 infants (GA 26.2±1.6 weeks) 140 (62%) could be stabilised with nCPAP in the delivery room, of whom 68 (49%; GA 26.9±1.5 weeks) succeeded on nCPAP with favourable outcome and 72 infants (51%; GA 26.3±1.4 weeks) failed nCPAP within 48 h at a median (IQR) age of 5.6 (3.3-19.3) h. History or initial blood gases were poor predictors of subsequent nCPAP failure. Intubation at fraction of inspired oxygen (FiO(2))≥0.35 versus 0.4 versus 0.45 instead of ≥0.6 would have resulted in unnecessary intubations of 16% versus 9% versus 6% of infants with nCPAP success but decreased the age at intubation of infants with nCPAP failure to 3.1 (2.2-5.2) versus 3.8 (2.5-8.7) versus 4.4 (2.7-10.9) h.

CONCLUSIONS

Medical history or initial blood gas values are poor predictors of subsequent nCPAP failure. A threshold FiO(2) of ≥0.35-0.45 compared to ≥0.6 for intubation would shorten the time to surfactant delivery without a relevant increase in intubation rate. An individualised approach with a trial of early nCPAP and prompt intubation and surfactant treatment at low thresholds may be the best approach in very low birthweight infants.

[Characterization of ENU-mutant mice. Animal models for human diseases using morphological and molecular methods]

Following sequencing of the human genome there are new challenges to decipher the knowledge concerning gene function and the role of gene interactions and pathways leading to disease. Mouse models have proven to be an ideal tool for this purpose. Point mutations induced by chemical mutagenesis by N-ethyl-N-nitrosourea (ENU) offer possibilities for the analysis of the phenotypic outcome of a single base pair exchange on the entire organism. The Munich ENU mouse mutagenesis project is part of the worldwide efforts to obtain mutations for each gene. The generation of new alleles or allelic series offers relevant insights into the relevance of single gene sections. Various mouse models for human diseases have been generated by a systematic large-scale genome-wide phenotyping screen in the last decade. This work illustrates how the implementation of the ENU mouse mutagenesis project with gene identification and parallel high-throughput screening is taking advantage of local cooperation with experienced phenotyping groups at the Helmholtz Zentrum München, leading to major advances in the functional analysis of the mammalian genome.

The Significance of the Impact Velocity of Vacuum-Deposited Atoms for the Structure of thin Films

The goal in this study was to investigate the effect of the impact velocity of the atoms on the structure of thin films generated by vacuum deposition. For that purpose all atoms faster or slower than a pre-selected velocity, u, were removed with a velocity filter frm a beam of gold atoms obtained by thermal evaporation in vacuum (10−5 Pa). The residual atoms (with a velocity u)were deposited onto cold (80 K) glass substrates. The annealing behaviour of the films studied by means of d.c. resistance measurements indicates a correlation between film structure and impact velocity in the sense that films generated by means of low velocity atoms have a non-equilibrium structure which does not exist in films prepared by conventional vacuum deposition.

Temperature dependence of energy dissipation on NaCl(001) in non-contact atomic force microscopy

The dissipative tip-sample interactions are measured by dynamic force spectroscopy for silicon tips on NaCl(001) in ultrahigh vacuum in the attractive and repulsive force regimes. Force and dissipation versus distance curves were obtained for different sample temperatures ranging from 35 to 285 K. Detailed comparison in different distance regimes shows that neither the force nor energy dissipation exhibits a systematic variation with sample temperature.

Improved immunotoxins with novel functional elements

Immunotoxins (ITs) are protein-based drugs combining a target-specific binding domain (usually derived from an antibody) and a cytotoxic domain to kill target cells. They are among the most promising new therapeutic tools to fight cancer, and several clinical trials have been completed with encouraging results. Although the targeted elimination of malignant cells is an elegant concept, there are numerous practical challenges that limit the clinical use of ITs, including inefficient cellular uptake, low cytotoxicity and off-target effects. Here we present some of the strategies that have been developed to improve the efficacy of ITs, particularly those involving the incorporation of functional peptide sequences into recombinant ITs to improve target binding, modify plasma half life and distribution, boost tumor penetration, enhance cellular uptake and increase cytotoxic efficiency.

The distribution of saponins in vivo affects their synergy with chimeric toxins against tumours expressing human epidermal growth factor receptors in mice

BACKGROUND AND PURPOSE

Certain saponins synergize with antitumour drugs to enhance their efficacy, but the mechanisms underlying this synergy in vivo are not well studied. Here, we describe the distribution of Saponinum album (Spn) from Gypsophila paniculata L. in mice after subcutaneous injection.

EXPERIMENTAL APPROACH

The [(3)H]-labelled Spn used for in vivo experiments was biologically active, as it still increased the cytotoxicity of a chimeric toxin in vitro. Distribution of [(3)H]-Spn was measured in BALB/c mice, with or without subcutaneous tumours in the flank. Labelled Spn was subcutaneously injected in the neck, and samples of organs, blood, urine and tumour tissue were analysed for radioactivity, 5-240 min after the injection.

KEY RESULTS

The majority of [(3)H]-Spn distributed within 10 min throughout the entire animal, with high levels of radioactivity in the urine by 30 min. No preferential accumulation in tumour tissue or other organs was observed. In tumour-bearing mice, using a sequential combination of Spn (given first) and a chimeric toxin against the epidermal growth factor receptor, ErbB1, we tested two different pretreatment times for Spn. There was high antitumour efficacy (66% inhibition of tumour growth) after 60 min pre treatment with Spn, but no significant inhibition after 10 min pre treatment with Spn.

CONCLUSIONS AND IMPLICATIONS

[(3)H]-Spn was rapidly cleared from the mice after s.c. injection, and antitumour synergy with chimeric toxins was correlated with the removal of excess Spn from tissues. Disposition of Spn in vivo may critically determine antitumour synergy with chimeric toxins.

Targeted disruption of the mouse Npal3 gene leads to deficits in behavior, increased IgE levels, and impaired lung function

The non-imprinted in Prader-Willi/Angelman syndrome (NIPA) proteins are highly conserved receptors or transporters. Translocation of NIPA genes were found in patients with Prader-Willi syndrome, and loss-of-function of the NIPA1 gene was identified in hereditary spastic paraplegia. The family of NIPA-like domain containing (NPAL) proteins is closely related to the NIPA proteins, but to date nothing is known about their function. Here, we could demonstrate that both human NPAL3 and mouse NPAL3 are ubiquitously expressed and encode highly conserved proteins. To further elucidate the function of the Npal3 gene, knockout (Npal3(-/-)) mice were generated. Intensive phenotypic analyses revealed that disruption of the Npal3 gene results in a pleiotropic phenotype. The function of the nervous system was impaired in both mutant males and females which could be demonstrated in behavioral tests. In addition, in NPAL3 mutants the number of NK cells was decreased and changes in IgM, IgG(2), and IgA were observed, indicating that the immune system is also affected. Interestingly, increased IgE levels as well as impaired lung functions were observed in mutant males but not in mutant females. It should be noted that the human Npal3 gene is located at 1p36.12-->p35.1, and atopic diseases were previously linked to this genomic region. Thus, the Npal3(-/-) mice could serve as a valuable model system for studying atopic diseases.

Enhancement of saporin cytotoxicity by Gypsophila saponins--more than stimulation of endocytosis

Saporin is a type I ribosome-inactivating protein with N-glycosidase activity. It removes adenine residues from the 28S ribosomal RNA resulting in inhibition of protein synthesis. Recently we have shown that saporin exerts no cytotoxicity on seven human cell lines. However, the combination of saporin with a special mixture of Gypsophila saponins (Soapwort saponins) from Gypsophila paniculata L. (baby's breath) rendered saporin to a potent cytotoxin comparable to viscumin, a highly toxic type II ribosome-inactivating protein. In this study we investigated whether the enhancement of the saporin-cytotoxicity by Gypsophila saponins is mediated by a saponin-triggered modulation of endocytosis, exocytosis or impaired degradation processes of his-tagged saporin ((his)saporin) in ECV-304 cells. For this purpose (his)saporin was labelled with tritium and cytotoxicity of the toxin alone and in combination with Gypsophila saponins was scrutinized. The transport and degradation processes of (his)saporin were not different in Gypsophila saponin-treated and control cells. However, after ultracentrifugation of a post-nuclear supernatant the amount of cytosolic (his)saporin was significantly higher in saponin-treated cells than in cells, which were only incubated with (his)saporin. This indicates a saponin mediated endosomal escape of saporin.

Submolecular features of epitaxially grown PTCDA on Cu(111) analyzed by force field spectroscopy

Submolecular features of epitaxially grown 3,4,9,10-perylenetetra-carboxylic-dianhydride (PTCDA) on Cu(111) are resolved in non-contact atomic force microscopy topography scans in ultrahigh vacuum. While molecules in the first layer above the Cu substrate are depicted as featureless ovals, the second layer molecules show an intramolecular structure with a height corrugation of up to 40 pm. Force field spectroscopy experiments with submolecular resolution show that the tip-molecule forces differ significantly on the first and second layer molecules. Possible contributions to these force differences from mechanical deformations of the molecules as well as the internal charge density distribution are discussed.