Quorum Sensing Peptides Selectively Penetrate the Blood-Brain Barrier

Bacteria communicate with each other by the use of signaling molecules, a process called ‘quorum sensing’. One group of quorum sensing molecules includes the oligopeptides, which are mainly produced by Gram-positive bacteria. Recently, these quorum sensing peptides were found to biologically influence mammalian cells, promoting i.a. metastasis of cancer cells. Moreover, it was found that bacteria can influence different central nervous system related disorders as well, e.g. anxiety, depression and autism. Research currently focuses on the role of bacterial metabolites in this bacteria-brain interaction, with the role of the quorum sensing peptides not yet known. Here, three chemically diverse quorum sensing peptides were investigated for their brain influx (multiple time regression technique) and efflux properties in an in vivo mouse model (ICR-CD-1) to determine blood-brain transfer properties: PhrCACET1 demonstrated comparatively a very high initial influx into the mouse brain (K_in = 20.87 μl/(g×min)), while brain penetrabilities of BIP-2 and PhrANTH2 were found to be low (K_in = 2.68 μl/(g×min)) and very low (K_in = 0.18 μl/(g×min)), respectively. All three quorum sensing peptides were metabolically stable in plasma (in vitro) during the experimental time frame and no significant brain efflux was observed. Initial tissue distribution data showed remarkably high liver accumulation of BIP-2 as well. Our results thus support the potential role of some quorum sensing peptides in different neurological disorders, thereby enlarging our knowledge about the microbiome-brain axis.     

Recognition of oxidized low density lipoprotein by the scavenger receptor of macrophages results from derivatization of apolipoprotein B by products of fatty acid peroxidation

Uptake of cholesterol-containing lipoproteins by macrophages in the arterial intima is believed to be an important step in the pathogenesis of atherosclerosis. There are a number of possible mechanisms by which macrophages might accumulate cholesterol, and one that has attracted much interest recently involves the uptake of oxidatively modified low density lipoprotein (LDL) via a specific cell surface receptor, termed the scavenger or acetyl-LDL receptor. Previous studies have shown that chemical derivatization of LDL with reagents that result in neutralization of the charge of lysine amino groups also allows recognition by this receptor. As well, it has been shown that oxidation of LDL is accompanied by a decrease in free lysine groups and binding of lipid products to apolipoprotein B. The present studies were done to further characterize the receptor-binding domain on oxidized LDL. It was found that LDL could be modified by incubation with water-soluble products derived from autoxidized unsaturated fatty acids under conditions that inhibited oxidation of the LDL itself. The LDL modified in this way had increased electrophoretic mobility but showed no evidence of the oxidative damage that typifies LDL oxidized by exposure to metal ions. Furthermore, the oxidation product-modified LDL was rapidly degraded by cultured macrophages through the scavenger receptor pathway. Bovine albumin modified by oxidation products also showed greatly accelerated degradation by macrophages. When analyzed by reverse-phase high pressure liquid chromatography, the reactive oxidation products appeared less polar than fatty acids or simple medium-chain aldehydes. When treated with the carbonyl reagent 2,4-dinitrophenylhydrazine, the reactive fractions yielded derivatives, some of which were identified by mass spectrometry as hydrazones of nonenal, heptenal, pentenal, and crotonaldehyde. A series of 2-unsaturated aldehydes (acrolein to 2-nonenal) were all found to modify LDL, but none of these aldehyde-modified LDLs were recognized by the scavenger receptor of macrophages and all were degraded much more slowly by these cells than LDL modified with oxidation products. Furthermore, copper-oxidized LDL had only very slight immunoreactivity toward a panel of antibodies specific for adducts of simple 2-unsaturated aldehydes. Analysis of underivatized autoxidized fatty acids by coupled liquid chromatography/thermospray mass spectrometry revealed compounds with m/z corresponding to M+17, M+31, and 2M+31 in fractions that were capable of modifying LDL. The unoxidized fatty acids showed a dominant peak at M-1. These results indicate that the scavenger receptor of macrophages can recogn     

Oestradiol, a new hapten for detecting nucleic acid sequences by FISH

 Oestradiol has been conjugated to allylamine-dUTP with an 11-atom spacer to allow enzymatic incorporation of the label into DNA sequences. In a comparative DNA and mRNA FISH study we have used DNA probes that were either labelled with digoxigenin, biotin or oestradiol. Results show that oestradiol-labelled probes can detect DNA and RNA sequences in FISH equally well as digoxigenin- and biotin-labelled probes. Further, no crossreactivity between the various hapten-specific antibodies and the three haptens were observed. Binding of the rabbit anti-oestradiol antibody to endogenous oestrogen in various tissues was not observed under the conditions tested. In view of the increasing demands for multi-colour DNA and mRNA FISH applications, oestradiol is a welcome addition to the collection of haptens employed in FISH. Accepted 20 June 1997     

Fitness costs of worker specialization for ant societies

Division of labour is of fundamental importance for the success of societies, yet little is known about how individual specialization affects the fitness of the group as a whole. While specialized workers may be more efficient in the tasks they perform than generalists, they may also lack the flexibility to respond to rapid shifts in task needs. Such rigidity could impose fitness costs when societies face dynamic and unpredictable events, such as an attack by socially parasitic slavemakers. Here, we experimentally assess the colony-level fitness consequences of behavioural specialization in Temnothorax longispinosus ants that are attacked by the slavemaker ant T. americanus. We manipulated the social organization of 102 T. longispinosus colonies, based on the behavioural responses of all 3842 workers. We find that strict specialization is disadvantageous for a colony''s annual reproduction and growth during slave raids. These fitness costs may favour generalist strategies in dynamic environments, as we also demonstrate that societies exposed to slavemakers in the field show a lower degree of specialization than those originating from slavemaker-free populations. Our findings provide an explanation for the ubiquity of generalists and highlight their importance for the flexibility and functional robustness of entire societies.     

Using Ecological Momentary Assessment in Testing the Effectiveness of an Alcohol Intervention: A Two-Arm Parallel Group Randomized Controlled Trial

Background

Alcohol consumption of college students has a fluctuating nature, which might impact the measurement of intervention effects. By using 25 follow-up time-points, this study tested whether intervention effects are robust or might vary over time.

Methods

Data were used from a two-arm parallel group randomized controlled trial applying ecological momentary assessment (EMA) with 30 data time-points in total. Students between 18 and 24 years old who reported heavy drinking in the past six months and who were ready to change their alcohol consumption were randomly assigned to the experimental (n = 456: web-based brief alcohol intervention) and control condition (n = 451: no intervention). Outcome measures were weekly alcohol consumption, frequency of binge drinking, and heavy drinking status.

Results

According to the intention-to-treat principle, regression analyses revealed that intervention effects on alcohol consumption varied when exploring multiple follow-up time-points. Intervention effects were found for a) weekly alcohol consumption at 1, 2, 3, 4, and 7 weeks follow-up, b) frequency of binge drinking at 1, 2, 7, and 12 weeks follow-up, and c) heavy drinking status at 1, 2, 7, and 16 weeks follow-up.

Conclusions

This research showed that the commonly used one and six month follow-up time-points are relatively arbitrary and not using EMA might bring forth erroneous conclusions on the effectiveness of interventions. Therefore, future trials in alcohol prevention research and beyond are encouraged to apply EMA when assessing outcome measures and intervention effectiveness.

Trial registration

Netherlands Trial Register NTR2665     

Association of cytomegalovirus and other pathogens with frailty and diabetes mellitus,but not with cardiovascular disease and mortality in psycho-geriatric patients; a prospective cohort study

Background

Studies about associations of infections with herpes viruses and other pathogens, such as Chlamydia pneumoniae (CP) and Helicobacter pylori (HP) with cardiovascular disease (CVD), diabetes mellitus (DM), frailty and/or mortality are conflicting. Since high levels of antibodies against these pathogens occur in the elderly, the role of these pathogens in morbidity and mortality of vulnerable elderly was explored.

Results

Blood samples of 295 community dwelling psycho-geriatric patients were tested for IgG antibodies to herpes simplex virus type 1 and 2, varicella zoster virus, Epstein Barr virus (EBV), cytomegalovirus (CMV), human herpes virus type 6 (HHV6), CP and HP. Frailty was defined with an easy-to-use previously described frailty risk score. Relative risks (RR) with 95% confidence intervals were calculated to evaluate associations between CVD, DM, frailty and pathogens. Pathogens as a predictor for subsequent mortality were tested using Kaplan Meier analyses and Cox proportional hazard models. The mean age was 78 (SD: 6.7) years, 20% died, 44% were defined as frail, 20% had DM and 49% had CVD. Presence of CMV antibody titers was associated with frailty, as shown by using both qualitative and quantitative tests, RR ratio 1.4 (95% CI: 1.003-2.16) and RR ratio 1.5 (95% CI: 1.06-2.30), respectively. High IgG antibody titers of HHV6 and EBV were associated with DM, RR ratio 3.3 (95% CI: 1.57-6.49). None of the single or combined pathogens were significantly associated with mortality and/or CVD.

Conclusions

Prior CMV infection is associated with frailty, which could be in line with the concept that CMV might have an important role in immunosenescence, while high IgG titers of HHV6 and EBV are associated with DM. No association between a high pathogen burden and morbidity and/or mortality could be demonstrated.

     

A Clinical Evaluation of Statin Pleiotropy: Statins Selectively and Dose-Dependently Reduce Vascular Inflammation

Statins are thought to reduce vascular inflammation through lipid independent mechanisms. Evaluation of such an effect in atherosclerotic disease is complicated by simultaneous effects on lipid metabolism. Abdominal aortic aneurysms (AAA) are part of the atherosclerotic spectrum of diseases. Unlike atherosclerotic occlusive disease, AAA is not lipid driven, thus allowing direct evaluation of putative anti-inflammatory effects. The anti-inflammatory potency of increasing doses (0, 20 or 40 mg/day) simvastatin or atorvastatin was evaluated in 63 patients that were at least 6 weeks on statin therapy and who underwent open AAA repair. A comprehensive analysis using immunohistochemistry, mRNA and protein analyses was applied on aortic wall samples collected during surgery. The effect of statins on AAA growth was analyzed in a separate prospective study in incorporating 142 patients. Both statins equally effectively and dose-dependently reduced aortic wall expression of NFκB regulated mediators (i.e. IL-6 (P<0.001) and MCP-1 (P<0.001)); shifted macrophage polarization towards a M2 phenotype (P<0.0003); selectively reduced macrophage-related markers such as cathepsin K and S (P<0.009 and 0.0027 respectively), and ALOX5 (P<0.0009), and reduced vascular wall NFκB activity (40 mg/day group, P<0.016). No effect was found on other cell types. Evaluation of the clinical efficacy of statins to reduce AAA progression did not indicate an effect of statins on aneurysm growth (P<0.337). Hence, in the context of AAA the clinical relevance of statins pleiotropy appears minimal.