Stability of the Gram Reaction

In the course of about 7000 examinations of Gram-positive aerobic bacteria, it was found that two distinct groups of Gram-positive organisms could be recognized. One group was illustrated by Micrococcus freudenreichii, the other by Bacillus anthracis. All individuals in a smear of the former remained positive even when the time of exposure to stain was greatly diminished and the time of exposure to decolorizer was greatly increased. Similar changes of technic when B. anthracis was used showed that about 70% of the individuals in a given smear became Gram-negative. The writer accordingly distinguishes between stable and unstable Gram-positive bacteria.     

Restriction-map variation associated with the G6PD polymorphism in natural populations of Drosophila melanogaster

Restriction-map variation was studied in 126 copies of the G6pd region in X chromosome lines of Drosophila melanogaster from North America, Europe, and Africa. Special attention was focused on the distribution of variation relative to the geographically variable polymorphism for two electrophoretic variants. Nucleotide heterozygosity as determined by eight six-cutter restriction enzymes for the 13-kb region is estimated, on the basis of the worldwide sample, to be 0.065%, which is the lowest value reported for any comparable region in the D. melanogaster genome. Significant linkage disequilibrium between electrophoretic alleles and restriction-site variation is observed for several sites. In contrast to published studies of other genetic regions, there are large insertions that reach significant frequencies and are found across considerable geographic distances. There is a clustering of this variation inside the first large intervening sequence of the G6PD gene.      

Immobilization of Burkholderia cepacia in polyurethane-based foams: embedding efficiency and effect on bacterial activity

Immobilization of the trichloroethylene-degrading bacterium Burkholderia cepacia was evaluated using hydrophilic polyurethane foam. The influence of several foam formulation parameters upon cell retention was examined. Surfactant type was a major determinant of retention; a lecithin-based compound retained more cells than pluronic- or silicone-based surfactants. Excessive amounts of surfactant led to increased washout of bacteria. Increasing the biomass concentration in the foam from 4.8 to 10.5% dry weight per wet weight of foam resulted in fewer cells being washed out. Embedding at reduced temperature did not significantly affect retention, while the use of a silane binding agent gave inconsistent results. The optimal formulation retained all but 0.2% of total embedded cells during passage of 2 L of water through columns containing 2 g of foam. All foam formulations tested reduced the culturability of embedded cells by several orders of magnitude, but O₂ consumption and CO₂ evolution rates of embedded cells were never less than 50% of those of free cells. Nutrient amendments stimulated an increase in cell volume and ribosomal activity in immobilized cells as indicated by hybridization studies using fluorescently labeled ribosomal probes. These results indicate that, although immobilized cells were mostly nonculturable, they were metabolically active and thus could be used for biodegradation of toxic compounds. Received 23 December 1996/ Accepted in revised form 13 March 1997     

Ice premelting during differential scanning calorimetry

Premelting at the surface of ice crystals is caused by factors such as temperature, radius of curvature, and solute composition. When polycrystalline ice samples are warmed from well below the equilibrium melting point, surface melting may begin at temperatures as low as -15 degrees C. However, it has been reported (. Biophys. J. 65:1853-1865) that when polycrystalline ice was warmed in a differential scanning calorimetry (DSC) pan, melting began at about -50 degrees C, this extreme behavior being attributed to short-range forces. We show that there is no driving force for such premelting, and that for pure water samples in DSC pans curvature effects will cause premelting typically at just a few degrees below the equilibrium melting point. We also show that the rate of warming affects the slope of the DSC baseline and that this might be incorrectly interpreted as an endotherm. The work has consequences for DSC operators who use water as a standard in systems where subfreezing runs are important.     

Global expression profiling of theophylline response genes in macrophages: evidence of airway anti-inflammatory regulation

Background

Theophylline has been used widely as a bronchodilator for the treatment of bronchial asthma and has been suggested to modulate immune response. While the importance of macrophages in asthma has been reappraised and emphasized, their significance has not been well investigated. We conducted a genome-wide profiling of the gene expressions of macrophages in response to theophylline.

Methods

Microarray technology was used to profile the gene expression patterns of macrophages modulated by theophylline. Northern blot and real-time quantitative RT-PCR were also used to validate the microarray data, while Western blot and ELISA were used to measure the levels of IL-13 and LTC4.

Results

We identified dozens of genes in macrophages that were dose-dependently down- or up-regulated by theophylline. These included genes related to inflammation, cytokines, signaling transduction, cell adhesion and motility, cell cycle regulators, and metabolism. We observed that IL-13, a central mediator of airway inflammation, was dramatically suppressed by theophylline. Real-time quantitative RT-PCR and ELISA analyses also confirmed these results, without respect to PMA-treated THP-1 cells or isolated human alveolar macrophages. Theophylline, rolipram, etazolate, db-cAMP and forskolin suppressed both IL-13 mRNA expression (~25%, 2.73%, 8.12%, 5.28%, and 18.41%, respectively) and protein secretion (<10% production) in macrophages. These agents also effectively suppressed LTC4 expression.

Conclusion

Our results suggest that the suppression of IL-13 by theophylline may be through cAMP mediation and may decrease LTC4 production. This study supports the role of theophylline as a signal regulator of inflammation, and that down regulation of IL-13 by theophylline may have beneficial effects in inflammatory airway diseases.     

Modulation of peripheral T-cell function by interleukin-7 in rheumatoid arthritis

Introduction

Interleukin-7 (IL-7) is a cytokine essential for T-cell lymphopoiesis, survival and polarization with an emerging role in autoimmunity. We previously demonstrated reduced levels of circulating IL-7 in rheumatoid arthritis (RA), although high amounts are expressed in joints, suggesting differences between systemic and synovial effects. We observed healthy levels of IL-7 in 48% of RA patients in clinical remission (CR) and aimed to investigate the consequences of IL-7 deficiency on T-cell responses.

Methods

We used RA patients with active disease and in CR presenting various levels of IL-7, to investigate its modulatory effects on T cells by analysing responses to phyto-haemagglutinin (PHA), expression of polarization or survival factors, or suppression by regulatory T cells (Tregs).

Results

IL-7 levels were normal (>10 pg/ml) in 48% of RA patients in CR. Amongst 63 CR patients followed up for 18 months, lack of IL-7 recovery was observed in 13 out of 15 (86%) patients experiencing relapse but only 11 out of 48 (23%) of those who did not (P = 0.0002). Binary regressions showed high significance for below normal IL-7 levels for self-reported maternal family history of arthritis (odds ratio (OR): 7.66, P = 0.006) and a trend for smoking (OR: 3.33, P = 0.068) with no further demographic or clinical associations. Serum IL-7 correlated with restored CD4⁺T-cell response to PHA (rho = 0.879); this was not related to an increase in T-cell proliferation capacity or expression of survival factors B-cell lymphoma 2 (BCL2) and BCL2-associated protein X (BAX). Expression of Th1 polarization factor (TBET) was also dependent on exposure to IL-7 in vivo (rho = 0.600). In contrast CD25^highTregs’ response to PHA was not affected by in vivo IL-7, but their suppression capabilities were related to circulating IL-7 (rho = 0.589). Co-stimulation with IL-7 (mimicking the joint environment) increased responsiveness of CD4⁺T-cells to PHA, lowering the ability of CD25^highTregs to suppress them.

Conclusions

Our data demonstrate that IL-7 has a critical role in modulating T-cell function in vivo, possibly explaining opposing effects observed systemically and in the joint. Lack of IL-7 recovery in CR by maintaining a suppressed immune system may be a determinant factor in the occurrence of relapse.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0511-3) contains supplementary material, which is available to authorized users.     

Molecular evolution of the MAGUK family in metazoan genomes

Background  

Development, differentiation and physiology of metazoans all depend on cell to cell communication and subsequent intracellular signal transduction. Often, these processes are orchestrated via sites of specialized cell-cell contact and involve receptors, adhesion molecules and scaffolding proteins. Several of these scaffolding proteins important for synaptic and cellular junctions belong to the large family of membrane-associated guanylate kinases (MAGUK). In order to elucidate the origin and the evolutionary history of the MAGUKs we investigated full-length cDNA, EST and genomic sequences of species in major phyla.