Regulation of IRK3 inward rectifier K+ channel by m1 acetylcholine receptor and intracellular magnesium

Inward rectifier K+ channels control the cell's membrane potential and neuronal excitability. We report that the IRK3 but not the IRK1 inward rectifier K+ channel activity is inhibited by m1 muscarinic acetylcholine receptor. This m1 modulation cannot be accounted for by protein kinase C, Ca2+, or channel phosphorylation, but can be mimicked by Mg2+. Based on quantitative analyses of IRK3 and two different IRK1 mutant channels bestowed with sensitivity to m1 modulation, we suggest that the resting Mg2+ level causes chronic inhibition of IRK3 channels, and m1 receptor stimulation may lead to an increase of cytoplasmic Mg2+ concentration and further channel inhibition, due to the ability of Mg2+ to lead these channels into a prolonged inactivated state.     

Genghis Khan (Gek) as a putative effector for Drosophila Cdc42 and regulator of actin polymerization

The small GTPases Cdc42 and Rac regulate a variety of biological processes, including actin polymerization, cell proliferation, and JNK/mitogen-activated protein kinase activation, conceivably via distinct effectors. Whereas the effector for mitogen-activated protein kinase activation appears to be p65PAK, the identity of effector(s) for actin polymerization remains unclear. We have found a putative effector for Drosophila Cdc42, Genghis Khan (Gek), which binds to Dcdc42 in a GTP-dependent and effector domain-dependent manner. Gek contains a predicted serine/threonine kinase catalytic domain that is 63% identical to human myotonic dystrophy protein kinase and has protein kinase activities. It also possesses a large coiled-coil domain, a putative phorbol ester binding domain, a pleckstrin homology domain, and a Cdc42 binding consensus sequence that is required for its binding to Dcdc42. To study the in vivo function of gek, we generated mutations in the Drosophila gek locus. Egg chambers homozygous for gek mutations exhibit abnormal accumulation of F-actin and are defective in producing fertilized eggs. These phenotypes can be rescued by a wild-type gek transgene. Our results suggest that this multidomain protein kinase is an effector for the regulation of actin polymerization by Cdc42.     

Linkage analysis of susceptibility to ozone-induced lung inflammation in inbred mice

Through a survey of all departments of pediatrics, neurology and neuropathology in Germany, we calculated the incidence of all major forms of leukodystrophy. Only diagnoses based on specific biochemical tests in association with typical findings and/or neuroradiologically proven white matter involvement were accepted. In accordance with these strict criteria, 617 cases of leukodystrophy were found (incidence of all forms: app. 2.0/100,000). Minimal incidence was estimated at 0.8/100,000 for adrenoleukodystrophy/adrenomyeloneuropathy (ALD/AMN), 0.6/100,000 for metachromatic leukodystrophy (MLD), and 0.6/100,000 for Krabbe disease. Thus ALD/AMN is apparently underdiagnosed in Germany. A considerable proportion of leukodystrophies could not be classified in spite of adequate diagnostic procedures in experienced centers.     

Molecular dynamics study on local structure of amorphous and liquid Al2O3

Microscopic features of liquid and amorphous alumina (Al₂O₃) were simulated by molecular dynamics calculations. The simulations were performed in an orthorhombic cell with 3000 particles using the Born-Mayer potential at temperatures of 0, 2500, 2700, and 3000 K under constant pressure. It was found that a large cluster of pores contained several thousand spherical pores, which were formed with radii larger than 0.73 Å. The observed variations of Al₂O₃ structures with atomic arrangements of AlO_x (x=3, 4, 5, and 6) are discussed.     

提升越南家具产业竞争力的途径

以创新理论为基础,通过对家具产品设计中创新因素的本质分析,论述了家具产品设计创新的内涵与特性;通过对越南家具设计的现状分析,指出越南家具产业在设计创新方面的缺乏。在此基础上,提出了基于家具设计创新的越南家具产业竞争力提升的途径,分别加强以人为本、以持续发展为指导思想、以环保作为任务、以文化为艺术灵魂和以高科技为手段。     

Truncating the putative membrane association region circumvents the difficulty of expressing hepatitis C virus protein E1 in Escherichia coli

The putative E1 of hepatitis C virus (HCV) was expressed in Escherichia coli using a glutathione-S-transferase (GST) fusion protein system. The full length E1 protein is difficult to express. A series of E1 DNA fragments was generated and used for expression vector construction. Fusion proteins containing the E1 C-terminal region could not be expressed. When this region was truncated, the fusion proteins were synthesized to high levels. The possibility of this C-terminal region hampering the production of fusion protein was further explored. A construct with this segment directly fused to the C-terminus of GST indeed generated no detectable recombinant protein. According to the predicted structure of E1, this region may have membrane-associating properties. The expression results suggest a general approach to facilitate the production of viral membrane proteins in prokaryotes. Furthermore, these recombinant E1 proteins generated as antigens were used for Western blotting with sera from HCV-infected individuals. It was found that E1 is antigenic during HCV natural infection.     

Validation of [13C]urea breath test for Helicobacter pylori using a simple gas chromatograph-mass selective detector

OBJECTIVE: Isotope ratio mass spectrometry (IRMS) is the accepted method for accurately measuring the 13CO2:12CO2 ratio in the non-invasive and non-radioactive [13C]urea breath test (13C-UBT) for Helicobactor pylori. The IRMS instrument, an expensive and highly specialized analyser, is rarely available. The objective of this project was to modify and validate the use of a simple bench-top gas chromatograph-mass selective detector (GC-MSD) for 13C-UBT. METHODS: Breath samples from 71 patients were taken at baseline and 30 min after ingestion of 100 mg [13C]urea. The breath samples were analysed using GC-MSD in the selected ion monitoring mode. The reference 13CO2:12CO2 ratio was from NBS19 obtained from the US National Institute of Standards and Technology. 13CO2:12CO2 ratios of the breath samples were determined. Excess delta per thousand (per mil, delta/thousand) of the 30 min sample over the baseline (deltadelta/thousand) of > or = 6deltadelta/thousand was considered H. pylori positive. Results from 13C-UBT and histology determined blind to each other were compared. RESULTS: The coefficient of variation of the reference 13CO2:12CO2 ratio was 0.06%. Using histology as the 'gold standard', the sensitivity (97.9%) and specificity (95.8%) of the GC-MSD 13C-UBT were comparable to those of other methods of H. pylori diagnosis. CONCLUSION: A gas chromatograph coupled to a mass selective detector that is available in many analytical and biomedical laboratories can be used for the 13C-UBT. This method will increase the availability and reduce the cost of this non-invasive, non-radioactive diagnostic test.     

Imaging approach to the diagnosis of pulmonary sequestration

PURPOSE: To describe the characteristic features of pulmonary sequestration (PS), to evaluate the usefulness of various imaging modalities, and to find a rational approach to accurate diagnosis. MATERIAL AND METHODS: Twenty-four patients with PS proved by operation and pathology were reviewed retrospectively. Plain chest films were done in all patients, bronchography in 3, sonography in 14, CT in 6 (including CT angiography in 1 case), MR in 8 (including MR angiography in 1 case) and aortography in 12 (including DSA in 1 case). RESULTS: Plain chest films demonstrated a solid mass in 14 patients and a cystic mass in 10. Bronchograms showed displacement of adjacent bronchi with no filling of contrast medium within the lesion in 2 cases, while another case had a blind intermediate portion of the right bronchus (hypoplasia of middle and lower lobes associated with extralobar sequestration). Sonography demonstrated a solid lung mass in 12 cases and a solid mass with cystic areas in 2, and detected vessel-like structures within the mass or in its surroundings in 12. Doppler analysis showed arterial spectral wave confirming a feeding artery. CT revealed a solid mass in all patients, a mass with low density area in 4, and emphysema surrounding the mass in 3. MR imaging depicted anomalous arteries in all patients and venous drainage in 4 cases. Aortography demonstrated anomalous systemic arterial supply to the PS in all patients. In this series, 21 cases (87.5%) were correctly diagnosed preoperatively by the imaging modalities. CONCLUSION: Plain chest films can provide a diagnostic clue to PS. Sonography, CT and MR are helpful for showing arterial blood supply and for making a definite diagnosis. We recommend a rational imaging approach for the diagnosis of PS.