Selenium in the central nervous system of rats exposed to 75-Sel-selenomethionine and sodium selenite

The aim of the present study is to investigate the accumulation and retention of organic and inorganic selenium in the central nervous system (CNS) of the rat. Selenium accumulation was investigated after oral treatment (3.0 mg Se/L drinking water) or ip injection (1.7 mg Se/kg body wt) of rats exposed to 75-Se L-selenomethionine (SeMeth) or sodium selenite (NaSe). Significant higher concentrations were observed after exposure to organic compared to inorganic selenium after oral as well as ip administration. Highest concentrations in both experiments were observed in cerebellum followed by the nearly identical levels in the cerebral hemisphere and spinal cord independent of the chemical form of selenium or the route of administration. The difference in concentrations observed between the different parts of the CNS investigated in each group were, however, not significant. Retention of selenium in the CNS was investigated after a single ip injection (1.7 mg Se/kg body wt) of 75-Se SeMeth or NaSe. In both groups, we observed an initial fast excretion phase followed by a slower excretion phase resembling a first-order reaction. Organic selenium disappeared much slower from all parts of the central nervous system compared to NaSe after a single injection.     

Flexibility in the donor substrate specificity of {beta} 1,4-galactosyltransferase: application in the synthesis of complex carbohydrates

Biosynthetically, bovine N-acetylglucosainine ß 1,4-galacto-syltransferase(GalT) catalyses the transfer of galactosyl residues from UDP-Galto the 4-position of GlcNAc units, resulting in the productionof N-acetyllactosamine sequences. UDP-Glc and UDP-GalNAc werealso found to act as donors for this enzyme, allowing the preparationof ßGlc(14)-ßGlcNAc and ßGalNAc(14)ßGlcNActerminating structures on the milligram scale. GalT could thusbe used to add ßGalNAc to ßGlcNAc(12)Manterminating structures, converting them to the ßGalNAc(14)ßGlcNAc(12)Mansequences found on glycoprotein hormones. GalT did not transferGlcNAc residues from UDP-GlcNAc, but it could utilize UDP-GlcNH₂as a donor. Synthesis of ßGlcNAc(14)ßGlcNAcsequences could therefore be accomplished by transfer of GlcNH₂from its UDP derivative, followed by N-acetylation of the productamino-disaccharide using acetic anhydride in methanol. The productsof the enzymatic reactions were characterized by ¹H-NMR-spectroscopyand fast-atom bombardment mass spectrometry. This work expandsthe scope of the combined chemical-enzymatic synthesis of complexcarbohydrates, using glycosyltrans-ferases, to the productionof oligosaccharides different from those for which these enzymeswere designed. These unnatural reactions should find applicationin glycoprotein and glycolipid remodelling. galactosyltransferase chemica1-enzymatic synthesis of oligosaccharides oligosaccharide analogues sugar-nucleotide analogues carbohydrate remodelling     

Chironomid communities as water quality indicators

Recent mathematical indices summarizing biological communities of indicators are recapitulated. Improvements of these indices based on weighting according to width of trophic ranges of each species are suggested. Their principle deficiencies, however, are pointed out.
Revised lists of characteristic profundal as well as littoral and sublittoral chironomids in Nearctic and Palearctic lakes show that at least 15 characteristic chironomid species communities can be delineated, 6 in each of the oligotrophic and the eutrophic ranges and 3 in the mesotrophic range. It is proposed that these communities be lettered consecutively in the Greek alphabet from α (alpha) to o (omikron). A key to the 15 divisions based on the species associations in the profundal zone of harmonic lakes is put forward. There is very good correlation between the 15 divisions and the ratios of average total phosphorus to mean lake depth and average chlorophyll a to mean lake depth.
The ratio of chironomids to oligochaetes and the distribution patterns of single species have proven useful in pin-pointing localized areas of pollution. The primary mechanism governing the distribution of chironomid communities in oligotrophic and mesotrophic lakes appears to be the availability of food materials rather than the annual hypolimnetic oxygen concentration. In eutrophic lakes the relationships between organic matter accumulation and oxygen levels are so interdependent as to be inseparable.     

Modelling the Human Immune System by Combining Bioinformatics and Systems Biology Approaches

Over the past decade a number of bioinformatics tools have been developed that use genomic sequences as input to predict to which parts of a microbe the immune system will react, the so-called epitopes. Many predicted epitopes have later been verified experimentally, demonstrating the usefulness of such predictions. At the same time, simulation models have been developed that describe the dynamics of different immune cell populations and their interactions with microbes. These models have been used to explain experimental findings where timing is of importance, such as the time between administration of a vaccine and infection with the microbe that the vaccine is intended to protect against. In this paper, we outline a framework for integration of these two approaches. As an example, we develop a model in which HIV dynamics are correlated with genomics data. For the first time, the fitness of wild type and mutated virus are assessed by means of a sequence-dependent scoring matrix, derived from a BLOSUM matrix, that links protein sequences to growth rates of the virus in the mathematical model. A combined bioinformatics and systems biology approach can lead to a better understanding of immune system-related diseases where both timing and genomic information are of importance.     

NetMHCIIpan-2.0 - Improved pan-specific HLA-DR predictions using a novel concurrent alignment and weight optimization training procedure

Background

Macrophages represent the front lines of our immune system; they recognize and engulf pathogens or foreign particles thus initiating the immune response. Imaging macrophages presents unique challenges, as most optical techniques require labeling or staining of the cellular compartments in order to resolve organelles, and such stains or labels have the potential to perturb the cell, particularly in cases where incomplete information exists regarding the precise cellular reaction under observation. Label-free imaging techniques such as Raman microscopy are thus valuable tools for studying the transformations that occur in immune cells upon activation, both on the molecular and organelle levels. Due to extremely low signal levels, however, Raman microscopy requires sophisticated image processing techniques for noise reduction and signal extraction. To date, efficient, automated algorithms for resolving sub-cellular features in noisy, multi-dimensional image sets have not been explored extensively.

Results

We show that hybrid z-score normalization and standard regression (Z-LSR) can highlight the spectral differences within the cell and provide image contrast dependent on spectral content. In contrast to typical Raman imaging processing methods using multivariate analysis, such as single value decomposition (SVD), our implementation of the Z-LSR method can operate nearly in real-time. In spite of its computational simplicity, Z-LSR can automatically remove background and bias in the signal, improve the resolution of spatially distributed spectral differences and enable sub-cellular features to be resolved in Raman microscopy images of mouse macrophage cells. Significantly, the Z-LSR processed images automatically exhibited subcellular architectures whereas SVD, in general, requires human assistance in selecting the components of interest.

Conclusions

The computational efficiency of Z-LSR enables automated resolution of sub-cellular features in large Raman microscopy data sets without compromise in image quality or information loss in associated spectra. These results motivate further use of label free microscopy techniques in real-time imaging of live immune cells.     

Preparation of androsta-1,4-diene-3,17-dione from sterols using Mycobacterium neoaurum VKPM As-1656 strain

A product of microbiological cleavage of the sterols side chain, androsta-1,4-diene-3,17-dione, is toxic for bacteria, in particular, actinobacteria of the genera Mycobacterium and Arthrobacter. Sterols were transformed into androsta-1,4-diene-3,17-dione by culturing the M. neoaurum VKPM An-1656 strain in a high yield, provided that a sorbent was used for elimination of contact between the bacterial cells and the product. Unlike the cholesterol side chain, the more branched chains of phytosterols were cleaved in the presence of M. neoaurum at a high rate only under turbulent stirring of the culture medium, which intensified the formation of hydrocarbonate ion from NaNI3 in situ.     

The effect of cooling rate, freeze-drying suspending fluid and culture age on the preservation of Campylobacter pylori

The effects of freezing rate, suspending fluid and age of culture on the ability of four strains of Campylobacter pylori to survive and recover from freeze-drying were examined. Freeze-drying by standard procedures generally resulted in an overall loss in viability of between 3 and 7 log units. The exact cause of poor recovery by C. pylori was not established but strain differences were detected, with NCTC 11637 (type strain) surviving better than NCTC 11638 and NCTC 11639. Recovery of the poorest growing strain (NE 26695) was notably more erratic. The largest loss in viability occurred at the primary drying stage. Losses resulting from freezing and secondary drying were less marked and the rate of freezing had only a marginal effect on recovery. Nineteen different freeze-drying suspending fluids were investigated. Overall the best recovery results were obtained with 5% inositol-broth (or horse serum) plus 25% glucose, at pH 7.0, in which loss of viability was typically about 4 log units. Other factors, such as age of culture and number of viable bacteria in the before-dry suspension, did not have a significant effect on survival. We conclude from these results that C. pylori can survive freeze-drying, albeit in small numbers, but the degree of recovery is apparently largely strain dependent.     

HIV Reactivation from Latency after Treatment Interruption Occurs on Average Every 5-8 Days—Implications for HIV Remission

HIV infection can be effectively controlled by anti-retroviral therapy (ART) in most patients. However therapy must be continued for life, because interruption of ART leads to rapid recrudescence of infection from long-lived latently infected cells. A number of approaches are currently being developed to ‘purge’ the reservoir of latently infected cells in order to either eliminate infection completely, or significantly delay the time to viral recrudescence after therapy interruption. A fundamental question in HIV research is how frequently the virus reactivates from latency, and thus how much the reservoir might need to be reduced to produce a prolonged antiretroviral-free HIV remission. Here we provide the first direct estimates of the frequency of viral recrudescence after ART interruption, combining data from four independent cohorts of patients undergoing treatment interruption, comprising 100 patients in total. We estimate that viral replication is initiated on average once every ≈6 days (range 5.1- 7.6 days). This rate is around 24 times lower than previous thought, and is very similar across the cohorts. In addition, we analyse data on the ratios of different ‘reactivation founder’ viruses in a separate cohort of patients undergoing ART-interruption, and estimate the frequency of successful reactivation to be once every 3.6 days. This suggests that a reduction in the reservoir size of around 50-70-fold would be required to increase the average time-to-recrudescence to about one year, and thus achieve at least a short period of anti-retroviral free HIV remission. Our analyses suggests that time-to-recrudescence studies will need to be large in order to detect modest changes in the reservoir, and that macaque models of SIV latency may have much higher frequencies of viral recrudescence after ART interruption than seen in human HIV infection. Understanding the mean frequency of recrudescence from latency is an important first step in approaches to prolong antiretroviral-free viral remission in HIV.     

Human breast microvascular endothelial cells retain phenotypic traits in long-term finite life span culture

Summary Attempts to study endothelial-epithelial interactions in the human breast have been hampered by lack of protocols for long-term cultivation of breast endothelial cells (BRENCs). The aim of this study was to establish long-term cultures of BRENCs and to compare their phenotypic traits with the tissue of origin. Microvasculature was localized in situ by immunohistochemitry in breast samples. From this tissue, collagen-rich stroma and adipose tissue were dissected mechanically and further disaggregated to release microvessel organoids BRENCs were cultured from these organoids in endothelial specific medium and characterized by staining for endothelial markers. Microvessels were a prominent feature of intralobular tissue as evidenced by immunostaining against endothelial specific markers such as CD31, VE-cadherin, and von Willebrand factor (VWF). Double staining against VE-cadherin and lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) showed that blood and lymphatic vessels could be distinguished. An antibody against CD31 was used to refine protocols for isolation of microvasculature from reduction mammoplasties. BRENCs retained critical traits even at high passage, including uptake of low-density lipoprotein, and had E-selectin induced upon treatment with tumor necrosis factor-α. The first signs of senescence in passage 14 were accompained by gain of trisomy 11. At passage 18 cells showed chromosomal aberrations and growth arrest as revealed by β-galactosidase staining. We demonstrate here that breast microvasculature may serve as a large-scale source for expansion of BRENCs with molecular and functional traits preserved. These cells will form the basis for studies on the role of endothelial cells in breast morphogenesis.