The Soluble Interleukin-6 Receptor Is a Mediator of Hematopoietic and Skeletal Actions of Parathyroid Hormone

Both PTH and IL-6 signaling play pivotal roles in hematopoiesis and skeletal biology, but their interdependence is unclear. The purpose of this study was to evaluate the effect of IL-6 and soluble IL-6 receptor (sIL-6R) on hematopoietic and skeletal actions of PTH. In the bone microenvironment, PTH stimulated sIL-6R protein levels in primary osteoblast cultures in vitro and bone marrow in vivo in both IL-6^+/+ and IL-6^−/− mice. PTH-mediated hematopoietic cell expansion was attenuated in IL-6^−/− compared with IL-6^+/+ bone marrow, whereas sIL-6R treatment amplified PTH actions in IL-6^−/− earlier than IL-6^+/+ marrow cultures. Blocking sIL-6R signaling with sgp130 (soluble glycoprotein 130 receptor) inhibited PTH-dependent hematopoietic cell expansion in IL-6^−/− marrow. In the skeletal system, although intermittent PTH administration to IL-6^+/+ and IL-6^−/− mice resulted in similar anabolic actions, blocking sIL-6R significantly attenuated PTH anabolic actions. sIL-6R showed no direct effects on osteoblast proliferation or differentiation in vitro; however, it up-regulated myeloid cell expansion and production of the mesenchymal stem cell recruiting agent, TGF-β1 in the bone marrow microenvironment. Collectively, sIL-6R demonstrated orphan function and mediated PTH anabolic actions in bone in association with support of myeloid lineage cells in the hematopoietic system.     

Estimation of bird distribution based on ring re‐encounters: precision and bias of the division coefficient and its relation to multi‐state models

Capsule The division coefficient is an estimate of the proportion of ringed birds migrating to different destination areas taking into account area‐specific re‐encounter probabilities.

Aims To explore precision and bias of the division coefficient method by a simulation study and to compare the approach with multi‐state models.

Methods In a simulation study true and estimated division coefficients were compared. The division coefficient method was mathematically compared with the multi‐state model.

Results The estimated division coefficients seemed to be unbiased if the assumptions were met. The precision decreased if the bird distribution became similar in both bird groups and when difference between area‐specific re‐encounter probabilities increased. A bootstrap method to assess precision is presented. The estimates from the division coefficient method equal the maximum likelihood estimates in a multi‐state model including only one time interval.

Conclusion Before applying the division coefficient method or a multi‐state model to real data a simulation study should be conducted in order to explore the behaviour of parameter estimation. The division coefficient method with the bootstrap confidence intervals is an easy alternative to a multi‐state model with one time interval when the bird distribution between destination areas (e.g. migratory connectivity) alone is of interest.     

Enhancing adhesion of yeast brewery strains to chamotte carriers through aminosilane surface modification

The adhesion of cells to solid supports is described as surface-dependent, being largely determined by the properties of the surface. In this study, ceramic surfaces modified using different organosilanes were tested for proadhesive properties using industrial brewery yeast strains in different physiological states. Eight brewing strains were tested: bottom-fermenting Saccharomyces pastorianus and top-fermenting Saccharomyces cerevisiae. To determine adhesion efficiency light microscopy, scanning electron microscopy and the fluorymetric method were used. Modification of chamotte carriers by 3-(3-anino-2-hydroxy-1-propoxy) propyldimethoxysilane and 3-(N, N-dimethyl-N-2-hydroxyethyl) ammonium propyldimethoxysilane groups increased their biomass load significantly.     

Selectivity of Ni(II) and Zn(II) binding to Sporosarcina pasteurii UreE, a metallochaperone in the urease assembly: a calorimetric and crystallographic study

Urease is a nickel-dependent enzyme that plays a critical role in the biogeochemical nitrogen cycle by catalyzing the hydrolysis of urea to ammonia and carbamate. This enzyme, initially synthesized in the apo form, needs to be activated by incorporation of two nickel ions into the active site, a process driven by the dimeric metallochaperone UreE. Previous studies reported that this protein can bind different metal ions in vitro, beside the cognate Ni(II). This study explores the metal selectivity and affinity of UreE from Sporosarcina pasteurii (Sp, formerly known as Bacillus pasteurii) for cognate [Ni(II)] and noncognate [Zn(II)] metal ions. In particular, the thermodynamic parameters of SpUreE Ni(II) and Zn(II) binding have been determined using isothermal titration calorimetry. These experiments show that two Ni(II) ions bind to the protein dimer with positive cooperativity. The high-affinity site involves the conserved solvent-exposed His¹⁰⁰ and the C-terminal His¹⁴⁵, whereas the low-affinity site comprises also the C-terminal His¹⁴⁷. Zn(II) binding to the protein, occurring in the same protein regions and with similar affinity as compared to Ni(II), causes metal-driven dimerization of the protein dimer. The crystal structure of the protein obtained in the presence of equimolar amounts of both metal ions indicates that the high-affinity metal binding site binds Ni(II) preferentially over Zn(II). The ability of the protein to select Ni(II) over Zn(II) was confirmed by competition experiments in solution as well as by analysis of X-ray anomalous dispersion data. Overall, the thermodynamics and structural parameters that modulate the metal ion specificity of the different binding sites on the protein surface of SpUreE have been established.     

Blood-Brain Barrier Breakdown after Embolic Stroke in Rats Occurs without Ultrastructural Evidence for Disrupting Tight Junctions

The term blood-brain barrier (BBB) relates to the ability of cerebral vessels to hold back hydrophilic and large molecules from entering the brain, thereby crucially contributing to brain homeostasis. In fact, experimental opening of endothelial tight junctions causes a breakdown of the BBB evidenced as for instance by albumin leakage. This and similar observations led to the conclusion that BBB breakdown is predominantly mediated by damage to tight junction complexes, but evidentiary ultrastructural data are rare. Since functional deficits of the BBB contribute to an increased risk of hemorrhagic transformation and brain edema after stroke, which both critically impact on the clinical outcome, we studied the mechanism of BBB breakdown using an embolic model of focal cerebral ischemia in Wistar rats to closely mimic the essential human pathophysiology. Ischemia-induced BBB breakdown was detected using intravenous injection of FITC-albumin and tight junctions in areas of FITC-albumin extravasation were subsequently studied using fluorescence and electron microscopy. Against our expectation, 25 hours after ischemia induction the morphology of tight junction complexes (identified ultrastructurally and using antibodies against the transcellular proteins occludin and claudin-5) appeared to be regularly maintained in regions where FITC-albumin massively leaked into the neuropil. Furthermore, occludin signals along pan-laminin-labeled vessels in the affected hemisphere equaled the non-affected contralateral side (ratio: 0.966 vs. 0.963; P = 0.500). Additional ultrastructural analyses at 5 and 25 h after ischemia induction clearly indicated FITC-albumin extravasation around vessels with intact tight junctions, while the endothelium exhibited enhanced transendothelial vesicle trafficking and signs of degeneration. Thus, BBB breakdown and leakage of FITC-albumin cannot be correlated with staining patterns for common tight junction proteins alone. Understanding the mechanisms causing functional endothelial alterations and endothelial damage is likely to provide novel protective targets in stroke.     

The Impact of Short-Term,Intensive Antifolate Treatment (with Pyrimethamine and Sulfadoxine) and Antibiotics Followed by Long-Term,Secondary Antifolate Prophylaxis on the Rate of Toxoplasmic Retinochoroiditis Recurrence

PurposeTo assess the impact of intensive antifolate treatment, followed by secondary antifolate prophylaxis (A-SP) on the recurrence rate of toxoplasmic retinochoroiditis (TRC). To investigate whether there are any other factors potentially predisposing for recurrence.ResultsWhen secondary antifolate prophylaxis (A-SP) was instituted immediately after the treatment for TRC, the probability of 3-year recurrence–free survival after the first course of A-SP was 90.9%. A recurrence was most likely approximately 3.5 years after the first treatment. A univariate Cox regression model demonstrated that a risk for recurrence was 2.82 times higher (p = 0.02) in patients with retinal scars. In the multivariate analysis, the risk for recurrence was 2.41 higher (p = 0.06). In patients with haemorrhagic lesions the risk for recurrence was lower, aRR = 0.17 (approaching borderline statistical significance p = 0.08).ConclusionsWith the institution of A-SP of immediately after the intensive treatment for TRC, i.e. when a reactivation was most likely, there was no recurrence during A-SP. Following A-SP the recurrence rates were low and recurrence-free periods tended to be longer. The treatment regimen employed had a beneficial effect on the recurrence interval as it reduced and delayed the highest probability of recurrence.     

Investigating DNA Radiation Damage Using X-Ray Absorption Spectroscopy

The biological influence of radiation on living matter has been studied for years; however, several questions about the detailed mechanism of radiation damage formation remain largely unanswered. Among all biomolecules exposed to radiation, DNA plays an important role because any damage to its molecular structure can affect the whole cell and may lead to chromosomal rearrangements resulting in genomic instability or cell death. To identify and characterize damage induced in the DNA sugar-phosphate backbone, in this work we performed x-ray absorption spectroscopy at the P K-edge on DNA irradiated with either UVA light or protons. By combining the experimental results with theoretical calculations, we were able to establish the types and relative ratio of lesions produced by both UVA and protons around the phosphorus atoms in DNA.     

The importance of stem cell engineering in head and neck oncology

Head and neck squamous cell carcinoma is the sixth leading cause of cancer worldwide. The most common risk factors are carcinogens (tobacco, alcohol), and infection of the human papilloma virus. Surgery is still considered as the treatment of choice in case of head and neck cancer, followed by a reconstructive surgery to enhance the quality of life in the patients. However, the widespread use of artificial implants does not provide appropriate physiological activities and often cannot act as a long-term solution for the patients. Here we review the applicability of multiple stem cell types for tissue engineering of cartilage, trachea, vocal folds and nerves for head and neck injuries. The ability of the cells to self-renew and maintain their pluripotency state makes them an attractive tool in tissue engineering.