Determinants of serum levels of surfactant proteins A and B and Clara cell protein CC16.

Increased leakage of surfactant proteins A and B (SP-A and SP-B) and Clara cell secretory protein (CC16) from the air spaces into the circulation occurs in a range of respiratory conditions. However, circulating levels depend not only on the rate of entry into the circulation, but also on the rate of clearance. In order to clarify the role of the kidney in the clearance of these proteins, serum levels were related to markers of glomerular filtration in 54 non-smoking patients with varying degrees of renal dysfunction, none of whom had respiratory disease or were receiving dialysis at the time of sampling. Serum SP-A was related to SP-B (r = 0.53, p < 0.001) and to CC16 (r = 0.33, p < 0.02). Similarly, SP-B was related to CC16 (r = 0.39, p < 0.004). Stepwise multiple linear regression analysis suggested that serum SP-A and SP-B are influenced by age (approximately 20 and approximately 25% of variance, respectively), whereas CC16 is determined by renal function and, to a lesser extent, by body weight (approximately 63% of variance in total). We conclude that CC16 is cleared from blood by the renal route, whereas SP-A and SP-B are not. Serum SP-A and SP-B are influenced by age, which we speculate reflects increased damage to the alveolocapillary barrier.     

Specific immuno capturing of the Staphylococcal superantigen toxic‐shock syndrome toxin‐1 in plasma

Toxic‐shock syndrome is primarily caused by the Toxic‐shock syndrome toxin 1 (TSST‐1), which is secreted by the Gram‐positive bacterium Staphylococcus aureus. The toxin belongs to a family of superantigens (SAgs) which exhibit several shared biological properties, including the induction of massive cytokine release and V_β‐specific T‐cell proliferation. In this study we explored the possibility to use monoclonal Variable domains of Llama Heavy‐chain antibodies (VHH) in the immuno capturing of TSST‐1 from plasma. Data is presented that the selected VHHs are highly specific for TSST‐1 and can be efficiently produced in large amounts in yeast. In view of affinity chromatography, the VHHs are easily coupled to beads, and are able to deplete TSST‐1 from plasma at very low, for example, pathologically relevant, concentrations. When spiked with 4 ng/mL TSST‐1 more than 96% of TSST‐1 was depleted from pig plasma. These data pave the way to further explore application of high‐affinity columns in the specific immuno depletion of SAgs in experimental sepsis models and in sepsis in humans. Biotechnol. Bioeng. 2009; 104: 143–151 © 2009 Wiley Periodicals, Inc.     

Cultured astrocytes derived from corpus callosum or cortical grey matter show distinct glutamate handling properties

While the astrocytic control of extracellular glutamate concentration at synaptic contacts is well characterized, little is known regarding the clearance of glutamate along axon tracts, even though local excitotoxic damage has been reported. Therefore, we have compared glutamate handling in astrocyte cultures derived from white matter (corpus callosum) and grey matter tissues (cortical structures). These populations of astrocytes showed clearly distinct phenotypes, adopting stellate or protoplasmic morphologies respectively. In addition, white matter astrocytes showed high densities of the intermediate filament proteins glial fibrillary acidic protein, vimentin and nestin. The glutamate–aspartate transporter and glutamate transporter‐1, as well as glutamine synthetase, were found to be expressed at higher levels in white matter compared with grey matter astrocytes. Consistent with this aspartate uptake capacity was three to fourfold higher in white matter cells, and the use of specific inhibitors revealed a substantial activity of glutamate transporter‐1, contrasting with grey matter cells where this transporter appeared poorly functional. In addition, expression of type 5 metabotropic glutamate receptors was considerably higher in white matter astrocytes where the agonist (S)‐3,5‐dihydroxyphenylglycine triggered a large release of intracellular calcium. Differences in these astrocyte cultures were also observed when exposed to experimental conditions that trigger glial activation. This study highlights typical features of cultured astrocytes derived from white matter tissues, which appear constitutively adapted to handle excitotoxic insults. Moreover, the expression and activity of the astroglial components involved in the control of glutamatergic transmission are reinforced when these cells are maintained under conditions mimicking a gliotic environment.     

Palliatieve zorg op een chronische psychiatrische afdeling voor ouderen

Elderly, psychiatric patients admitted to a long-stay ward become physically ill and die. Which care can be offered on the ward and which cases require transferring a patient to specialized psychiatric-medical wards or a hospice? We studied 40 cases of death by malignancy in a clinic for elderly, long-term admitted psychiatric patients. Transferring the patient to such a ward was never indicated. Our population appeared to have a lack of awareness of their illness and expressed very few physical complaints. The possibilities of curative treatment of the malignancy were limited; the emphasis of the treatment was on palliative care. Because of the intensive support given on the patients ward the patients were able to die in peace. Deep sedation was never required.     

Pertussis: a matter of immune modulation

Pertussis, or whooping cough, is a highly contagious, acute respiratory disease of humans that is caused by the Gram-negative bacterial pathogen Bordetella pertussis. In the face of extensive global vaccination, this extremely monomorphic pathogen has persisted and re-emerged, causing approximately 300,000 deaths each year. In this review, we discuss the interaction of B. pertussis with the host mucosal epithelium and immune system. Using a large number of virulence factors, B. pertussis is able to create a niche for colonization in the human respiratory tract. The successful persistence of this pathogen is mainly due to its ability to interfere with almost every aspect of the immune system, from the inhibition of complement- and phagocyte-mediated killing to the suppression of T- and B-cell responses. Based on these insights, we delineate ideas for the rational design of improved vaccines that can target the 'weak spots' in the pathogenesis of this highly successful pathogen.     

From microbial gene essentiality to novel antimicrobial drug targets

Background

Bacterial respiratory tract infections, mainly caused by Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are among the leading causes of global mortality and morbidity. Increased resistance of these pathogens to existing antibiotics necessitates the search for novel targets to develop potent antimicrobials.

Result

Here, we report a proof of concept study for the reliable identification of potential drug targets in these human respiratory pathogens by combining high-density transposon mutagenesis, high-throughput sequencing, and integrative genomics. Approximately 20% of all genes in these three species were essential for growth and viability, including 128 essential and conserved genes, part of 47 metabolic pathways. By comparing these essential genes to the human genome, and a database of genes from commensal human gut microbiota, we identified and excluded potential drug targets in respiratory tract pathogens that will have off-target effects in the host, or disrupt the natural host microbiota. We propose 249 potential drug targets, 67 of which are targets for 75 FDA-approved antimicrobials and 35 other researched small molecule inhibitors. Two out of four selected novel targets were experimentally validated, proofing the concept.

Conclusion

Here we have pioneered an attempt in systematically combining the power of high-density transposon mutagenesis, high-throughput sequencing, and integrative genomics to discover potential drug targets at genome-scale. By circumventing the time-consuming and expensive laboratory screens traditionally used to select potential drug targets, our approach provides an attractive alternative that could accelerate the much needed discovery of novel antimicrobials.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-958) contains supplementary material, which is available to authorized users.     

Antiviral activity of Rwandan medicinal plants against human immunodeficiency virus type-1 (HIV-1)

Selected plants used in Rwandan traditional medicine for the treatment of infections and/or rheumatoid diseases were investigated for antiviral activity in vitro against human immunodeficiency virus type-1 (HIV-1). Of the 38 tested 80% ethanolic extracts, belonging to plants of 21 different families only the extracts from the leaves of Aspilia pluriseta (Asteraceae) and Rumex bequaertii (Polygonaceae) had interesting selectivity indices (SI = ratio of the 50% cytotoxic concentration to the 50% effective antiviral concentration) higher than 1. Further fractionation of the initially antivirally inactive ethanolic extract of Tithonia diversifolia, however, led to an aqueous fraction with a high anti-HIV-1 activity (SI > 461), indicating that the cytotoxicity of some plant components may mask the antiviral properties of the active plant substances in total plant extracts.