Trypanosome Motion Represents an Adaptation to the Crowded Environment of the Vertebrate Bloodstream

Blood is a remarkable habitat: it is highly viscous, contains a dense packaging of cells and perpetually flows at velocities varying over three orders of magnitude. Only few pathogens endure the harsh physical conditions within the vertebrate bloodstream and prosper despite being constantly attacked by host antibodies. African trypanosomes are strictly extracellular blood parasites, which evade the immune response through a system of antigenic variation and incessant motility. How the flagellates actually swim in blood remains to be elucidated. Here, we show that the mode and dynamics of trypanosome locomotion are a trait of life within a crowded environment. Using high-speed fluorescence microscopy and ordered micro-pillar arrays we show that the parasites mode of motility is adapted to the density of cells in blood. Trypanosomes are pulled forward by the planar beat of the single flagellum. Hydrodynamic flow across the asymmetrically shaped cell body translates into its rotational movement. Importantly, the presence of particles with the shape, size and spacing of blood cells is required and sufficient for trypanosomes to reach maximum forward velocity. If the density of obstacles, however, is further increased to resemble collagen networks or tissue spaces, the parasites reverse their flagellar beat and consequently swim backwards, in this way avoiding getting trapped. In the absence of obstacles, this flagellar beat reversal occurs randomly resulting in irregular waveforms and apparent cell tumbling. Thus, the swimming behavior of trypanosomes is a surprising example of micro-adaptation to life at low Reynolds numbers. For a precise physical interpretation, we compare our high-resolution microscopic data to results from a simulation technique that combines the method of multi-particle collision dynamics with a triangulated surface model. The simulation produces a rotating cell body and a helical swimming path, providing a functioning simulation method for a microorganism with a complex swimming strategy.     

Histological Criteria for Encapsulating Peritoneal Sclerosis – A Standardized Approach

Background

The two most relevant pathologies of long-term peritoneal dialysis (PD) are simple sclerosis and encapsulating peritoneal sclerosis (EPS). The histological differentiation of those two entities is difficult. The Aim of the study was to establish a method to standardize and facilitate the differentiation between simple sclerosis and EPS

Methods

We investigated 58 peritoneal biopsies - 31 EPS patients and 27 PD patients. Two blinded investigators analyzed 20 histological characteristics in EPS and PD patients.

Results

The following findings were significantly more common in EPS than in patients on PD without EPS: fibroblast like cells (FLC) (p<0.0001), mesothelial denudation (p<0.0001), decreased cellularity (p = 0.008), fibrin deposits (p<0.03), Fe deposits (p = 0.05), podoplanin vascular (p<0.0001), podoplanin avascular (p<0.0001). Using all predictor variables we trained the classification method Random Forest to categorize future cases. Podoplanin vascular and avascular were taken together (p<0.0001), FLC (p<0.0001), mesothelial denudation (p = 0.0005), calcification (p = 0.0026), acellular areas (p = 0.0094), and fibrin deposits (p = 0.0336) showed up as significantly important predictor variables. Estimated misclassification error rate when classifying new cases turned out to be 14%.

Conclusion

The introduced statistical method allows discriminating between simple sclerosis and EPS. The misclassification error will likely improve with every new case added to the database.     

Synthesis and antimicrobial activity of some new pyrazole derivatives containing a ferrocene unit

A series of new imines and amines have been synthesized by condensation of 1H-3-ferrocenyl-1-phenylpyrazole-4-carboxaldehyde with the corresponding amines, followed by reduction with sodium borohydride. The synthesized compounds have been screened for their in vitro antimicrobial activity against 11 bacteria and three fungal/yeast strains, using disc diffusion and broth microdilution susceptibility assays. They have shown a wide range of activities, from completely inactive to the highly active compounds.     

Viral Population Estimation Using Pyrosequencing

The diversity of virus populations within single infected hosts presents a major difficulty for the natural immune response as well as for vaccine design and antiviral drug therapy. Recently developed pyrophosphate-based sequencing technologies (pyrosequencing) can be used for quantifying this diversity by ultra-deep sequencing of virus samples. We present computational methods for the analysis of such sequence data and apply these techniques to pyrosequencing data obtained from HIV populations within patients harboring drug-resistant virus strains. Our main result is the estimation of the population structure of the sample from the pyrosequencing reads. This inference is based on a statistical approach to error correction, followed by a combinatorial algorithm for constructing a minimal set of haplotypes that explain the data. Using this set of explaining haplotypes, we apply a statistical model to infer the frequencies of the haplotypes in the population via an expectation–maximization (EM) algorithm. We demonstrate that pyrosequencing reads allow for effective population reconstruction by extensive simulations and by comparison to 165 sequences obtained directly from clonal sequencing of four independent, diverse HIV populations. Thus, pyrosequencing can be used for cost-effective estimation of the structure of virus populations, promising new insights into viral evolutionary dynamics and disease control strategies.     

The possibility of prevention of type 2 diabetes

INTRODUCTION: The aim of this study was to examine usefulness of oral glucose tolerance test (OGTT) in clinical evaluation of different glucose metabolism disturbances in subjects with at least one risk factor of type 2 diabetes. We compared the effectiveness of non-pharmacological and pharmacological prevention and treatment regiments on metabolic control in these individuals. MATERIAL AND METHODS: The study involved 130 patients, with the following characteristics: age between 18 to 76 years, mean body mass index (BMI) - 31.82 +/- 7.24 kg/m(2), and presence of at least one of the risk factor of type 2 diabetes. Glucose metabolism disturbances were diagnosed according to World Health Organization (WHO) criteria. Non-pharmacological regiments were applied for 3 months for patients with impaired glucose tolerance (IGT) and type 2 diabetes. Patients, whose still met criteria for type 2 diabetes during OGTT after non-pharmacological treatment were scheduled for pharmacological interventions. These patients were assigned at random to two groups, that were treated with either metformin or acarbose. The measurements of total cholesterol (TC), HDL-cholesterol , LDL-cholesterol, trigliceryde (TG), glucose, HbA(1c) and/or OGGT were performed during each visit. We also assessed risk factors for type 2 diabetes in these subjects. RESULTS: The prevalence of abnormal glucose tolerance in subjects with at least one of the risk factor of diabetes type 2 was near 40%. OGTT in these subjects increased the possibility of diagnosis diabetes type 2 and IGT. Hypertension (81%), hypercholesterolemia (71.4%), hypertriglicerydemia (71.4%) and obesity (66.7%) were the most frequent risk factors observed. There were no differences in biochemical measurements between these groups of patients. CONCLUSIONS: Individuals with at least one risk factor of type 2 diabetes should have screening test to diagnose glucose intolerance. Both non-pharmacological and pharmacological intervention was effective in normalization of glucose OGTT in patients with diabetes type 2 and IGT in newly diagnosed with disease patients.     

Intensity of transmission and spread of gene mutations linked to chloroquine and sulphadoxine-pyrimethamine resistance in falciparum malaria

The number of malaria parasite clones per infection-multiplicity of parasite clones-is affected by the transmission intensity, multiplicity increases with increasing transmission. This affects the frequency of parasites' sexual recombination and, if several mutations in different genes are involved, can break down drug resistant genotypes. Therefore, the effects of malaria transmission intensity on the spread of drug resistance could vary depending on the number of genes involved. Here we show that, compared to low transmission, intermediate-high transmission is associated with a 20-100-fold lower risk for the mutations linked to chloroquine resistance and a 6-17 times higher risk for those linked to sulphadoxine-pyrimethamine resistance. This is consistent with the hypothesis of a multigenic basis for chloroquine resistance and a monogenic basis for that of sulphadoxine-pyrimethamine. Reducing transmission intensity could slow the spread of resistance. However, a reduction below a critical threshold (e.g. when parasite prevalence in children 2-9 years old is around 60-80%) could, paradoxically, accelerate the spread of resistance to chloroquine and possibly to other drug combinations whose basis is multigenic. Our findings have important implications for malaria control because increasing drug resistance has a substantial impact on mortality.     

Two-photon excitation fluorometric measurement of homogeneous microparticle immunoassay for C-reactive protein

Recent developments in infrared laser technology have enabled the design of a compact instrumentation for two-photon excitation microparticle fluorometry (TPX). The microparticles can be used in immunoassays as the antibody-coated solid phase to capture an antigen and then detect it with a fluorescently labeled tracer antibody. Unlike most other methods, TPX technology allows low-volume, homogeneous immunoassays with real-time measurements of assay particles in the presence of a moderate excess of fluorescent tracer. In this study, the TPX assay system was used for the reagent characterization and the measurement of C-reactive protein (CRP) in diluted plasma samples, targeting the assay range useful in infectious disease diagnosis. The pentameric structure of the CRP permitted the optimization of an assay with the lowest detectable concentration of 1 microg/L (7.5 pM) by using a single monoclonal antibody both for capture and as the tracer. With a 1:200 predilution of samples, the measurement range of the assay was 1-150 mg/L, but an additional 1:10 dilution was required for higher concentrations. The TPX method showed a good correlation with the reference result obtained in a routine hospital laboratory, demonstrating the feasibility of the technology for immunodiagnostic applications.