Observation of Umklapp processes in non-crystalline materials

Umklapp processes are known to exist in cristalline materials, where they control important properties such as thermal conductivity, heat capacity and electrical conductivity. In this work we report the provocative observation of Umklapp processes in a non-periodical system, namely liquid Lithium. The lack of a well defined periodicity seems then not to prevent the existence of these scattering processes mechanisms provided that the local order of the systems i.e. the maxima of the static structure factor supply the equivalent of a reciprocal lattice vector in the case of cristalline materials.Comment: 13 pages P

Determinants of respiratory symptom development in patients with chronic airflow obstruction

SummaryBackgroundThis study was undertaken to identify the determinants of respiratory symptom development in patients with chronic airflow obstruction (CAO).MethodsCategories of symptomatic and asymptomatic CAO were defined using questionnaire responses and spirometric results. We analyzed data obtained as part of the second South Korean National Health and Nutrition Examination Survey (Korean NHANES II).ResultsAmong 187 patients with CAO, 69 had no respiratory symptoms. CAO patients with symptoms were significantly older than those without symptoms (P=0.026), and hypertension was more common among symptomatic CAO patients than among asymptomatic CAO patients (P=0.005). According to questionnaire responses, symptomatic CAO patients had more difficulty in walking or lifting (P<0.001), required more help with personal care (P=0.01), and had poorer general health than asymptomatic CAO patients (P=0.008). Symptomatic CAO patients had higher fasting blood glucose levels than asymptomatic CAO patients (P=0.028). Symptomatic CAO patients had significantly lower forced expiratory volume in 1s (FEV1) (P=0.001), forced vital capacity (FVC) (P=0.008), and a ratio of FEV1/FVC than asymptomatic CAO patients (P<0.001). Statistically significant predictors of symptom development were as follows: age (odds ratio (OR) 1.04, P=0.028), hypertension (OR 4.41, P=0.008), fasting blood glucose (OR 1.02, P=0.034), FEV1 (OR 0.07, P=0.002), FVC (OR 0.08, P=0.009), FEV1/FVC (OR 0.00, P=0.001). Multiple logistic regression analyses revealed two independent factors associated with symptom development: FEV1/FVC (OR 0.001, P=0.002) and hypertension (OR 5.95, P=0.005).ConclusionsIn CAO, respiratory symptom development is significantly associated with low FEV1/FVC and the presence of hypertension

The first small-molecule inhibitors of members of the ribonuclease E family

The Escherichia coli endoribonuclease RNase E is central to the processing and degradation of all types of RNA and as such is a pleotropic regulator of gene expression. It is essential for growth and was one of the first examples of an endonuclease that can recognise the 5′-monophosphorylated ends of RNA thereby increasing the efficiency of many cleavages. Homologues of RNase E can be found in many bacterial families including important pathogens, but no homologues have been identified in humans or animals. RNase E represents a potential target for the development of new antibiotics to combat the growing number of bacteria that are resistant to antibiotics in use currently. Potent small molecule inhibitors that bind the active site of essential enzymes are proving to be a source of potential drug leads and tools to dissect function through chemical genetics. Here we report the use of virtual high-throughput screening to obtain small molecules predicted to bind at sites in the N-terminal catalytic half of RNase E. We show that these compounds are able to bind with specificity and inhibit catalysis of Escherichia coli and Mycobacterium tuberculosis RNase E and also inhibit the activity of RNase G, a paralogue of RNase E

Insight into the Assembly Properties and Functional Organisation of the Magnetotactic Bacterial Actin-like Homolog, MamK

Magnetotactic bacteria (MTB) synthesize magnetosomes, which are intracellular vesicles comprising a magnetic particle. A series of magnetosomes arrange themselves in chains to form a magnetic dipole that enables the cell to orient itself along the Earth’s magnetic field. MamK, an actin-like homolog of MreB has been identified as a central component in this organisation. Gene deletion, fluorescence microscopy and in vitro studies have yielded mechanistic differences in the filament assembly of MamK with other bacterial cytoskeletal proteins within the cell. With little or no information on the structural and behavioural characteristics of MamK outside the cell, the mamK gene from Magnetospirillium gryphiswaldense was cloned and expressed to better understand the differences in the cytoskeletal properties with its bacterial homologues MreB and acitin. Despite the low sequence identity shared between MamK and MreB (22%) and actin (18%), the behaviour of MamK monitored by light scattering broadly mirrored that of its bacterial cousin MreB primarily in terms of its pH, salt, divalent metal-ion and temperature dependency. The broad size variability of MamK filaments revealed by light scattering studies was supported by transmission electron microscopy (TEM) imaging. Filament morphology however, indicated that MamK conformed to linearly orientated filaments that appeared to be distinctly dissimilar compared to MreB suggesting functional differences between these homologues. The presence of a nucleotide binding domain common to actin-like proteins was demonstrated by its ability to function both as an ATPase and GTPase. Circular dichroism and structural homology modelling showed that MamK adopts a protein fold that is consistent with the ‘classical’ actin family architecture but with notable structural differences within the smaller domains, the active site region and the overall surface electrostatic potential

Purification and Characterization of Two New Allergens from the Venom of Vespa magnifica

Due to poor diagnostic facilities and a lack of medical alertness, allergy to Vespa wasps may be underestimated. Few allergens have been identified from Vespa wasps

PREDICTORS OF HYPERTENSION

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74570/1/j.1749-6632.1978.tb25565.x.pd

Endocrinologic, neurologic, and visual morbidity after treatment for craniopharyngioma

Craniopharyngiomas are locally aggressive tumors which typically are focused in the sellar and suprasellar region near a number of critical neural and vascular structures mediating endocrinologic, behavioral, and visual functions. The present study aims to summarize and compare the published literature regarding morbidity resulting from treatment of craniopharyngioma. We performed a comprehensive search of the published English language literature to identify studies publishing outcome data of patients undergoing surgery for craniopharyngioma. Comparisons of the rates of endocrine, vascular, neurological, and visual complications were performed using Pearson’s chi-squared test, and covariates of interest were fitted into a multivariate logistic regression model. In our data set, 540 patients underwent surgical resection of their tumor. 138 patients received biopsy alone followed by some form of radiotherapy. Mean overall follow-up for all patients in these studies was 54 ± 1.8 months. The overall rate of new endocrinopathy for all patients undergoing surgical resection of their mass was 37% (95% CI = 33–41). Patients receiving GTR had over 2.5 times the rate of developing at least one endocrinopathy compared to patients receiving STR alone or STR + XRT (52 vs. 19 vs. 20%, χ2P < 0.00001). On multivariate analysis, GTR conferred a significant increase in the risk of endocrinopathy compared to STR + XRT (OR = 3.45, 95% CI = 2.05–5.81, P < 0.00001), after controlling for study size and the presence of significant hypothalamic involvement. There was a statistical trend towards worse visual outcomes in patients receiving XRT after STR compared to GTR or STR alone (GTR = 3.5% vs. STR 2.1% vs. STR + XRT 6.4%, P = 0.11). Given the difficulty in obtaining class 1 data regarding the treatment of this tumor, this study can serve as an estimate of expected outcomes for these patients, and guide decision making until these data are available