The Acoela: on their kind and kinships, especially with nemertodermatids and xenoturbellids (Bilateria incertae sedis)

Acoels are among the simplest worms and therefore have often been pivotal in discussions of the origin of the Bilateria. Initially thought primitive because of their “planula-like” morphology, including their lumenless digestive system, they were subsequently dismissed by many morphologists as a specialized clade of the Platyhelminthes. However, since molecular phylogenies placed them outside the Platyhelminthes and outside all other phyla at the base of the Bilateria, they became the focus of renewed debate and research. We review what is currently known of acoels, including information regarding their morphology, development, systematics, and phylogenetic relationships, and put some of these topics in a historical perspective to show how the application of new methods contributed to the progress in understanding these animals. Taking all available data into consideration, clear-cut conclusions cannot be made; however, in our view it becomes successively clearer that acoelomorphs are a “basal” but “divergent” branch of the Bilateria.     

Dynamics of the Cag‐type IV secretion system of Helicobacter pylori as studied by bacterial co‐infections

Many pathogenic Gram‐negative bacteria possess type IV secretion systems (T4SS) to inject effector proteins directly into host cells to modulate cellular processes to their benefit. The human bacterial pathogen Helicobacter pylori, a major aetiological agent in the development of chronic gastritis, duodenal ulcer and gastric carcinoma, harbours the cag‐T4SS to inject the cytotoxin associated Antigen (CagA) into gastric epithelial cells. This results in deregulation of major signalling cascades, actin‐cytoskeletal rearrangements and eventually gastric cancer. We show here that a pre‐infection with live H. pylori has a dose‐dependent negative effect on the CagA translocation efficiency of a later infecting strain. This effect of the ‘first’ strain was independent of any of its T4SS, the vacuolating cytotoxin (VacA) or flagella. Other bacterial pathogens, e.g. pathogenic Escherichia coli, Campylobacter jejuni, Staphylococcus aureus, or commensal bacteria, such as lactobacilli, were unable to interfere with H. pylori's CagA translocation capacity in the same way. This interference was independent of the β1 integrin receptor availability for H. pylori, but certain H. pylori outer membrane proteins, such as HopI, HopQ or AlpAB, were essential for the effect. We suggest that the specific interference mechanism induced by H. pylori represents a cellularresponse to restrict and control CagA translocation into a host cell to control the cellular damage.     

Protein composition and biomechanical properties of in vivo-derived basement membranes

Basement membranes (BMs) evolved together with the first metazoan species approximately 500 million years ago. Main functions of BMs are stabilizing epithelial cell layers and connecting different types of tissues to functional, multicellular organisms. Mutations of BM proteins from worms to humans are either embryonic lethal or result in severe diseases, including muscular dystrophy, blindness, deafness, kidney defects, cardio-vascular abnormalities or retinal and cortical malformations. In vivo-derived BMs are difficult to come by; they are very thin and sticky and, therefore, difficult to handle and probe. In addition, BMs are difficult to solubilize complicating their biochemical analysis. For these reasons, most of our knowledge of BM biology is based on studies of the BM-like extracellular matrix (ECM) of mouse yolk sac tumors or from studies of the lens capsule, an unusually thick BM. Recently, isolation procedures for a variety of BMs have been described, and new techniques have been developed to directly analyze the protein compositions, the biomechanical properties and the biological functions of BMs. New findings show that native BMs consist of approximately 20 proteins. BMs are four times thicker than previously recorded, and proteoglycans are mainly responsible to determine the thickness of BMs by binding large quantities of water to the matrix. The mechanical stiffness of BMs is similar to that of articular cartilage. In mice with mutation of BM proteins, the stiffness of BMs is often reduced. As a consequence, these BMs rupture due to mechanical instability explaining many of the pathological phenotypes. Finally, the morphology and protein composition of human BMs changes with age, thus BMs are dynamic in their structure, composition and biomechanical properties.     

Genetic and Non-Genetic Determinants of Raltegravir Penetration into Cerebrospinal Fluid: A Single Arm Pharmacokinetic Study

Background

Antiretroviral drugs vary in their central nervous system penetration, with better penetration possibly conferring neurocognitive benefit during human immunodeficiency virus (HIV) therapy. The efflux transporter gene ABCB1 is expressed in the blood-brain barrier, and an ABCB1 variant (3435C→T) has been reported to affect ABCB1 expression. The integrase inhibitor raltegravir is a substrate for ABCB1. We examined whether ABCB1 3435C→T affects raltegravir disposition into cerebrospinal fluid (CSF), and explored associations with polymorphisms in other membrane transporter genes expressed in the blood-brain barrier.

Methods

Forty healthy, HIV-negative adults of European descent (20 homozygous for ABCB1 3435 C/C, 20 homozygous for 3435 T/T, each group divided equally between males and females) were given raltegravir 400 mg twice daily for 7 days. With the final dose, plasma was collected for pharmacokinetic analysis at 9 timepoints over 12 hours, and CSF collected 4 hours post dose.

Results

The 4-hour CSF concentration correlated more strongly with 2-hour (r²=0.76, P=1.12x10^-11) than 4-hour (r²=0.47, P=6.89x10^-6) single timepoint plasma concentration, and correlated strongly with partial plasma area-under-the-curve values (AUC_0-4h r²=0.86, P=5.15x10^-16). There was no significant association between ABCB1 3435C→T and ratios of CSF-to-plasma AUC or concentration (p>0.05 for each comparison). In exploratory analyses, CSF-to-plasma ratios were not associated with 276 polymorphisms across 16 membrane transporter genes.

Conclusions

Among HIV-negative adults, CSF raltegravir concentrations do not differ by ABCB1 3435C→T genotype but strongly correlate with plasma exposure.

Trial Registration

ClinicalTrials.gov NCT00729924 http://clinicaltrials.gov/show/NCT00729924     

Estimates of Excess Medically Attended Acute Respiratory Infections in Periods of Seasonal and Pandemic Influenza in Germany from 2001/02 to 2010/11

Background

The number of patients seeking health care is a central indicator that may serve several different purposes: (1) as a proxy for the impact on the burden of the primary care system; (2) as a starting point to estimate the number of persons ill with influenza; (3) as the denominator data for the calculation of case fatality rate and the proportion hospitalized (severity indicators); (4) for economic calculations. In addition, reliable estimates of burden of disease and on the health care system are essential to communicate the impact of influenza to health care professionals, public health professionals and to the public.

Methodology/Principal Findings

Using German syndromic surveillance data, we have developed a novel approach to describe the seasonal variation of medically attended acute respiratory infections (MAARI) and estimate the excess MAARI attributable to influenza. The weekly excess inside a period of influenza circulation is estimated as the difference between the actual MAARI and a MAARI-baseline, which is established using a cyclic regression model for counts. As a result, we estimated the highest ARI burden within the last 10 years for the influenza season 2004/05 with an excess of 7.5 million outpatient visits (CI95% 6.8–8.0). In contrast, the pandemic wave 2009 accounted for one third of this burden with an excess of 2.4 million (CI95% 1.9–2.8). Estimates can be produced for different age groups, different geographic regions in Germany and also in real time during the influenza waves.     

The antitumor activity of hydrophobin SC3, a fungal protein

The use of mushroom extracts has been common practice in traditional medicine for centuries, including the treatment of cancer. Proteins called hydrophobins are very abundant in mushrooms. Here, it was examined whether they have antitumor activity. Hydrophobin SC3 of Schizophyllum commune was injected daily intraperitoneally starting 1 day after tumor induction in two tumor mouse models (sarcoma and melanoma). SC3 reduced the size and weight of the melanoma significantly, but the sarcoma seemed not affected. However, microscopic analysis of the tumors 12 days after induction revealed a strong antitumor effect of SC3 on both tumors. The mitotic activity of the tumor decreased 1.6- (melanoma) to 2.3-fold (sarcoma), while the vital mass decreased 2.3- (melanoma) to 4.3-fold (sarcoma) compared to the control. Treatment did not cause any signs of toxicity. Behavior, animal growth, and weight of organs were similar to animals injected with vehicle, and no histological abnormalities were found in the organs. In vitro cell culture studies revealed no direct cytotoxic effect of SC3 towards sarcoma cells, while cytotoxic activity was observed towards melanoma cells at a high SC3 concentration. Daily treatment with SC3 did not result in detectable levels of anti-SC3 antibodies in the plasma. Instead, a cellular immune response was observed. Incubation of spleen cells with SC3 resulted in a 1.5- to 2.5-fold increase in interleukin-10 and TNF-α mRNA levels. In conclusion, the nontoxic fungal hydrophobin SC3 showed tumor-suppressive activity possibly via immunomodulation and may be of benefit as adjuvant in combination with chemotherapy and radiation.     

Linear fusigen as the major hydroxamate siderophore of the ectomycorrhizal Basidiomycota Laccaria laccata and Laccaria bicolor

A screening for siderophores produced by the ectomycorrhizal fungi Laccaria laccata and Laccaria bicolor in synthetic low iron medium revealed the release of several different hydroxamate siderophores of which four major siderophores could be identified by high resolution mass spectrometry. While ferricrocin, coprogen and triacetylfusarinine C were assigned as well as other known fungal siderophores, a major peak of the siderophore mixture revealed an average molecular mass of 797 for the iron-loaded compound. High resolution mass spectrometry indicated an absolute mass of m/z = 798.30973 ([M + H]⁺). With a relative error of Δ = 0.56 ppm this corresponds to linear fusigen (C₃₃H₅₂N₆O₁₃Fe; MW = 797.3). The production of large amounts of linear fusigen by these basidiomycetous mycorrhizal fungi may possibly explain the observed suppression of plant pathogenic Fusarium species. For comparative purposes Fusarium roseum was included in this study as a well known producer of cyclic and linear fusigen.