Cellular UDP-glucose deficiency caused by a single point mutation in the UDP-glucose pyrophosphorylase gene

We previously isolated a mutant cell that is the only mammalian cell reported to have a persistently low level of UDP-glucose. In this work we obtained a spontaneous revertant whose UDP-glucose level lies between those found in the wild type and the mutant cell. The activity of UDP-glucose pyrophosphorylase (UDPG:PP), the enzyme that catalyzes the formation of UDP-glucose, was in the mutant 4% and in the revertant 56% of the activity found in the wild type cell. Sequence analysis of UDPG: PP cDNAs from the mutant cell showed one missense mutation, which changes amino acid residue 115 from glycine to aspartic acid. The substituted glycine is located within the largest stretch of strictly conserved residues among eukaryotic UDPG:PPs. The analysis of the cDNAs from the revertant cell indicated the presence of an equimolar mixture of the wild type and the mutated mRNAs, suggesting that the mutation has reverted in only one of the alleles. In summary, we demonstrate that the G115D substitution in the Chinese hamster UDPG:PP dramatically impairs its enzymatic activity, thereby causing cellular UDP-glucose deficiency.     

Motor performance in Alzheimer''s disease

A 47-year-old man with Hirayama's disease who developed cervical spondylotic amyotrophy (CSA) is presented. The patient had noted weakness and atrophy of hand and forearm muscles bilaterally at the age of 16. At the age of 40, he developed proximal muscle atrophy and weakness bilaterally after 20 years of a non-progressive state. Myelography and computed tomography (CT)-myelography revealed that ventral cord compression at multiple levels of C4-7 vertebral bodies was increased when the neck was extended. The clinical diagnosis was CSA associated with Hirayama's disease. To our knowledge, this is the first such case to be reported.     

2,3,4- or 2,3,5-trisubstituted furans: catalyst-controlled highly regioselective ring-opening cycloisomerization reaction of cyclopropenyl ketones

2,3,4- or 2,3,5-trisubstituted furans were highly regioselectively formed from the cycloisomerization reaction of the same starting cyclopropenes 1 via the subtle choice of the transition metal halides. Under the catalysis of 5 mol % PdCl2(CH3CN)2, 2,3,5-trisubstituted furans 2 were given in 50-88% yields with 95-99% regioselectivities, while 2,3,4-trisubstituted furans 3 were formed in 78-96% yields with 99% regioselectivities under the catalysis of 5 mol % CuI.     

Production and properties of micro‐porous glas bubble zinc and aluminium composites

Micro‐porous syntactic foams were produced by means of integration of glass bubbles into aluminium and zinc matrices. Preforms of glass bubbles were pressure infiltrated with the alloys AlSi9Cu9 ans ZnAl4Cu using squeeze casting. The preforms were sintered thermically without the use of bonding agents. Using the combination of different sintering steps syntactic foams with locally different densities could be produced. The mechanical properties of the foams were tested indicating a high compression strength of the foams and a very good compression energy absorption. Furthermore, corrosion behaviour and behaviour at higher temperatures were investigated.     

Photoluminescent properties of flexible PVC compounds and their interpretation for performance analysis of automotive exterior parts

Study of fluorescence emission from flexible PVC‐based formulations, colored by exposure to road asphalt or degraded thermally or by UV aging, shows that fluorescent species are formed during the interaction of PVC with road asphalt. For the conditions found in exterior automotive applications, no other known degradation causes development of fluorescence. Flexible PVC‐based formulations discolored by asphalt staining or degraded thermally at moderate temperatures bleach completely under conditions of natural or artificial weathering. A simple technique, using visually observed photoluminescence and photobleaching, can thus identify photoactive groups formed during the interaction of PVC with road asphalt. Application of this test method will allow selective improvement of failed asphalt resistance without treating the “overall” stability of a compound.     

A Maximum Entropy Approach for Collaborative Filtering

Collaborative filtering (CF) involves predicting the preferences of a user for a set of items given partial knowledge of the user's preferences for other items, while leveraging a database of profiles for other users. CF has applications e.g. in predicting Web sites a person will visit and in recommending products. Fundamentally, CF is a pattern recognition task, but a formidable one, often involving a huge feature space, a large data set, and many missing features. Even more daunting is the fact that a CF inference engine must be capable of predicting any (user-selected) items, given any available set of partial knowledge on the user's other preferences. In other words, the model must be designed to solve any of a huge (combinatoric) set of possible inference tasks. CF techniques include memory-based, classification-based, and statistical modelling approaches. Among these, modelling approaches scale best with large data sets and are the most adept at handling missing features. The disadvantage of these methods lies in the statistical assumptions (e.g. feature independence), which may be unjustified. To address this shortcoming we propose a new model-based CF method, based on the maximum entropy principle. For the MS Web application, the new method is demonstrated to outperform a number of CF approaches, including naive Bayes and latent variable (cluster) models, support vector machines (SVMs), and the (Pearson) correlation method.     

Extended fundamental frequency analysis of the LCC resonant converter

Fundamental frequency techniques are used to analyze the series-parallel resonant converter under heavy load conditions, both with a continuous, but distorted parallel capacitor voltage waveform, and with a discontinuous capacitor voltage waveform. The analysis is validated with results from an experimental prototype. The application of the technique to the parallel-loaded L-C resonant converter is also considered.