Does intracellular histamine mediate mast cell histamine release?

Previously, we demonstrated that through binding a novel intracellular receptor of microM affinity (HIC), histamine mediates, and the HIC antagonist N,N-diethyl-2-[4-(phenylmethyl)phenoxy]ethanamine. HCl (DPPE) inhibits, platelet aggregation and serotonin granule secretion; the latter response is dependent upon the same processes that mediate histamine release from mast cell granules. We now show that, as for platelet serotonin release, DPPE blocks concanavalin A-stimulated mast cell histamine release with a potency (IC50 = 30 microM) greater than the H1-antagonist, pyrilamine (IC50 = 150 microM) or the H2-antagonist cimetidine (IC50 = 5 mM), correlating with rank order of potency to inhibit 3H-histamine binding in rat brain membranes and liver microsomes. We postulate that histamine release from mast cells is mediated at HIC by second messenger intracellular histamine. However, unlike platelets, mast cells do not appear to rely on newly synthesized histamine. Rather, as for calcium, histamine may be mobilized from bound stores to mediate histamine secretion.     

A new method for the quantification of superoxide dismutase mimics with an allopurinol–xanthine oxidase–lucigenin enhanced system

Allopurinol is a prodrug converted to oxypurinol by xanthine oxidase, a process followed by an efficient enzyme inhibition. Using a lucigenin-enhanced chemiluminescence method, we found that, under alkaline conditions, superoxide radicals are produced in large amounts in the first step of the interaction between the enzyme and the inhibitor. A comparison between lucigenin and cytochrome c as final detectors revealed that only the chemiluminescence technique is able to detect the superoxide anions from allopurinol oxidation. The allopurinol–xanthine oxidase–lucigenin system can be used for the quantification of various free-radical scavengers, in particular superoxide dismutase mimics. Three manganese compounds from different structural classes [manganese(II) chloride, manganese N,N′-bis(salicylidiene)ethylenediamine chloride, and manganese(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin] were compared at five concentrations (0.01, 0.1, 1, 10, and 100 μM). The method is fast, 16 times more sensitive than the cytochrome c assay at pH 10.1 and could be used for in vivo investigations avoiding the lucigenin redox cycle. If the concentrations of the reagents are increased and Tween 20 is added, the method is also operative at pH 7.4.     

Safety Indices during Fetal Echocardiography at the Time of First-Trimester Scan Are Machine Dependent

The aim of our study was to evaluate the thermal index (TI) and mechanical index (MI), during the assessment of the fetal heart at the time of first-trimester scan, with different ultrasound machines. This was part of an observational study conducted in patients undergoing routine first-trimester screening. Cases were examined with Voluson E8 or 730Pro scanners using 2–8 MHz transabdominal probes. TI and MI were retrieved from the saved displays while in gray mode, color flow mapping and pulsed-wave (PW) Doppler examinations of the fetal heart and also from the ductus venosus (DV) assessment. We evaluated 552 fetal cardiac examinations, 303 (55%) performed with Voluson E8 and 249 (45%) with Voluson 730Pro ultrasound machines. The gray-scale exam of the heart and the PW Doppler DV assessment had TI values significantly lower for the Voluson E8 group (median, 0.04 vs. 0.2 and 0.1 vs. 0.2, respectively). The MI values from gray-scale and color flow mapping of the heart were significantly lower (median, 0.6 vs, 1.2 and 0.7 vs. 1) and for PW Doppler exam of the tricuspid flow were significantly higher (median 0.4 vs. 0.2) in the Voluson E8 group. The TI values from Doppler examinations of the heart, either color flow or PW imaging and MI values from DV assessment were not significantly different between the two groups. A different (newer) generation of ultrasound equipment provides lower or at least the same safety indices for most of the first-trimester heart examinations.     

RRM proteins interacting with the cap region of topoisomerase I

RNA recognition motif (RRM) domains bind both nucleic acids and proteins. Several proteins that contain two closely spaced RRM domains were previously found in protein complexes formed by the cap region of human topoisomerase I, a nuclear enzyme responsible for DNA relaxation or phosphorylation of SR splicing proteins. To obtain molecular insight into specific interactions between the RRM proteins and the cap region of topo I we examined their binary interactions using the yeast two-hybrid system. The interactions were established for hnRNP A1, p54(nrb) and SF2/ASF, but not for hnRNP L or HuR. To identify the amino acid pattern responsible for binding, experimental mutagenesis was employed and computational modelling of these processes was carried out. These studies revealed that two RRM domains and six residues of the consensus sequence are required for the binding to the cap region. On the basis of the above data, a structural model for the hnRNP A1-topoisomerase I complex was proposed. The main component of the hnRNP A1 binding site is a hydrophobic pocket on the beta-surface of the first RRM domain, similar to that described for Y14 protein interacting with Mago. We demonstrated that the interaction between RRM domains and the cap region was important for the kinase reaction catalyzed by topoisomerase I. Together with the previously described inhibitory effect of RRM domains of SF2/ASF on DNA cleavage, the above suggests that the binding of RRM proteins could regulate the activity of topoisomerase I.     

Age‐related ultrastructural changes of the basement membrane in the mouse blood‐brain barrier

The blood‐brain barrier (BBB) is essential for a functional neurovascular unit. Most studies focused on the cells forming the BBB, but very few studied the basement membrane (BM) of brain capillaries in ageing. We used transmission electron microscopy and electron tomography to investigate the BM of the BBB in ageing C57BL/6J mice. The thickness of the BM of the BBB from 24‐month‐old mice was double as compared with that of 6‐month‐old mice (107 nm vs 56 nm). The aged BBB showed lipid droplets gathering within the BM which further increased its thickness (up to 572 nm) and altered its structure. The lipids appeared to accumulate toward the glial side of the BM. Electron tomography showed that the lipid‐rich BM regions are located in small pockets formed by the end‐feet of astrocytes. These findings suggest an imbalance of the lipid metabolism and that may precede the structural alteration of the BM. These alterations may favour the accretion of abnormal proteins that lead to neurodegeneration in ageing. These findings warrant further investigation of the BM of brain capillaries and of adjoining cells as potential targets for future therapies.     

A label-free nanoparticle aggregation assay for protein complex/aggregate detection and study

The detection, analysis, and understanding of protein complexes/aggregates and their formation process are extremely important for biomolecular research, diagnosis, and biopharmaceutical development. Unfortunately, techniques that can be used conveniently for protein complex/aggregate detection and analysis are very limited. Using gold nanoparticle immunoprobes coupled with dynamic light scattering (DLS), we developed a label-free nanoparticle aggregation immunoassay (NanoDLSay) for protein aggregate detection and study. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), a protein target used routinely in Western blot as a loading control, is demonstrated here as an example. Through this study, we discovered that GAPDH has a strong tendency to form large aggregates in certain buffer solutions at a concentration range of 10-25 μg/ml. The strong light scattering property of gold nanoparticles immunoprobes greatly enhanced the sensitivity of the dynamic light scattering for protein complex/aggregate detection. In contrast to fluorescence techniques for protein complex and aggregation study, the protein targets do not need to be labeled with fluorescent probe molecules in NanoDLSay. NanoDLSay is a very convenient and sensitive tool for protein complex/aggregate detection and study.     

Parasitic Helminths from Paraguay. I. Sobolevicanthus dlouhyi n.sp. (Cestoda,Hymenoledididae) found in Amazonetta brasiliensis Gmelin

Summary Sobolevicanthus dlouhyi n. sp. is close to S. krabbeella but differs from it firstly by the longer rostellar hooks (83–85 m instead of 56–64 m). The cirrus pouch is shorter in the new species, no longer than the width of the widest proglottis, whereas in S. krabbeella it is twice as long. ac]19810312     

Variations and trends of birch pollen seasons during 15 years (1996–2010) in relation to weather conditions in Poznań (western Poland)

Birch (Betula) pollen seasons were examined in relation to meteorological conditions in Poznań (1996–2010). Birch pollen grains were collected using a volumetric spore trap. An alternate biennial cycle of birch pollen season intensity was noticed in Poznań. The main factors influencing birch pollen season intensity were average daily minimum temperatures during the second fortnight of May and the month of June one year before pollination as well as the intensity of the pollen season of the previous year. Most of the pollen grains are recorded during the first week of the season; the number of pollen grains recorded at this time is positively correlated with mean maximum temperature and negatively correlated with daily rainfall. The significant effect of rainfall in reducing the season pollen index was noticed only during weak pollen seasons (season pollen index <?mean). In addition, mean daily maximum temperature during the first two weeks of the birch pollen season markedly influences its duration. No significant trends in duration and intensity of the pollen season were recorded, however, a slight tendency towards early pollination was observed (?0.4 days/year, p?=?0.310).     

Highly Loaded Behavior of Kinesins Increases the Robustness of Transport Under High Resisting Loads

Kinesins are nano-sized biological motors which walk by repeating a mechanochemical cycle. A single kinesin molecule is able to transport its cargo about 1 μm in the absence of external loads. However, kinesins perform much longer range transport in cells by working collectively. This long range of transport by a team of kinesins is surprising because the motion of the cargo in cells can be hindered by other particles. To reveal how the kinesins are able to accomplish their tasks of transport in harsh intracellular circumstances, stochastic studies on the kinesin motion are performed by considering the binding and unbinding of kinesins to microtubules and their dependence on the force acting on kinesin molecules. The unbinding probabilities corresponding to each mechanochemical state of kinesin are modeled. The statistical characterization of the instants and locations of binding are captured by computing the probability of unbound kinesin being at given locations. It is predicted that a group of kinesins has a more efficient transport than a single kinesin from the perspective of velocity and run length. Particularly, when large loads are applied, the leading kinesin remains bound to the microtubule for long time which increases the chances of the other kinesins to bind to the microtubule. To predict effects of this behavior of the leading kinesin under large loads on the collective transport, the motion of the cargo is studied when the cargo confronts obstacles. The result suggests that the behavior of kinesins under large loads prevents the early termination of the transport which can be caused by the interference with the static or moving obstacles.