MauE and MauD proteins are essential in methylamine metabolism of Paracoccus denitrificans

Electrical field stimulation (EFS) produced relaxation of contracted arteries in the presence of tetrodotoxin. In the present study the contributions of vascular smooth muscle repolarization and endothelial release of nitric oxide to the relaxation response were investigated using isolated rat tail arteries and bovine aortic endothelial cells (BAEC). Intact and endothelium-denuded rings or intact, pressurized artery segments were contracted with either phenylephrine or KCl prior to EFS. Electrical field stimulation induced a small relaxation in denuded, phenylephrine contracted rings that was inhibited by the K+ channel blockers glibenclamide and BaCl2. In intact, phenylephrine-contracted rings, EFS induced significantly larger relaxations that were inhibited by BaCl2 as well as by L-NAME, an inhibitor of nitric oxide (NO) synthase, and methylene blue. EFS-induced relaxations were completely inhibited when BaCl2 and L-NAME or methylene blue were combined. Exposure to Ca(2+)-free buffer or diltiazem also inhibited the relaxation while ascorbic acid had no effect. Effluent from electrically stimulated BAEC caused denuded, phenylephrine contracted rings to relax. The ability of the effluent to cause relaxation was almost completely blocked by exposure of the BAEC to L-NAME or exposure of the recipient vascular smooth muscle to methylene blue; glibenclamide caused partial blockade. Simultaneous measurements of membrane potential and intraluminal pressure showed that EFS-induced membrane repolarization preceded changes in steady-state pressure. It is concluded that (1) the smooth muscle cells possess an endothelium-independent repolarization mechanism, (2) EFS causes endothelial cells of intact arteries to release NO and possibly a hyperpolarizing factor, (3) EFS of BAEC causes release of NO, and (4) EFS-induced relaxation depends on vascular smooth muscle cell membrane repolarization and endothelial cell release of vasoactive substances.     

Slow fusion of liposomes composed of membrane-spanning lipids

Vascular calcification (VC), which is described in the elderly and in diabetics, is frequently seen in uraemia. It is usually regarded as having little significance. We studied the roentgenological appearance of VC in a homogeneous group of 38 long-hours haemodialysis patients whose longevity on dialysis allowed sustained (10-25 years) follow-up, including annual skeletal surveys and thrice-yearly clinical examinations and biochemical profiles. We compiled a dossier of clinical and laboratory parameters from the start of dialysis to the present day. We were able to analyze the natural history of VC and to determine which clinical parameters were linked with progression. We found that VC became steadily more prevalent-at dialysis onset present in 39% of the patients, but in 92% after an average dialysis duration of 16 years, with a mean onset 9.7 years after starting dialysis. As well as becoming more prevalent, the calcification became progressively more severe in most patients. There were two patterns of VC: axial (aorta and iliac and femoral arteries), seen alone in 32% of the patients, and peripheral (digital arteries), seen alone in 3% of patients. Most patients (65%) had evidence of both types. Calcification was scored for site and severity. Patient age (r = 0.57, p < 0.001), systolic blood pressure (r = 0.54, p < 0.001), hyperparathyroidism (reduced progression after parathyroidectomy), plasma phosphate (r = 0.34, p = 0.042), and vitamin D concentrations (r = 0.53, p < 0.001) were the principal determinants of severity and rate of progression of VC in this population. There was a weak negative association between progression and serum ferritin (r = -0.33, p = 0.046). The reduced vessel compliance that results from VC is likely to be cardiovascularly deleterious. In severe cases, tissue perfusion or vascular access for haemodialysis can be compromised. VC and accelerated cardiovascular mortality are common to uraemia, diabetes, and systolic hypertension in the elderly. Better understanding of these pathological processes may permit intervention and possibly lead to a reduction in cardiovascular mortality.     

Amplified expression, purification and functional reconstitution of the dipeptide and tripeptide transport protein of Lactococcus lactis

Transport of hydrophilic dipeptides and tripeptides into Lactococcus lactis is mediated by a proton-motive-force-driven peptide-transport protein (DtpT) that shares similarity to eukaryotic peptide transporters, e.g. from yeasts, plants, and the kidney and small intestine of rabbit, man and rat. The expression level of DtpT protein in L. lactis was increased (20-40-fold) to approximately 10% of total integral membrane protein by means of a low-copy-number vector and selecting the appropriate growth conditions. Membrane vesicles bearing the DtpT-His6 protein (containing a C-terminal factor-Xa cleavage site and a six-histidine-tag) showed a Pro-Ala uptake activity that was half that of membranes containing the wild-type protein. The activity in the DtpT-His6 membrane vesicles increased at least 50% upon removal of the His6 tag from the protein. More than 95% DtpT was solubilized from L. lactis membranes in the presence of 1% (mass/vol.) n-dodecyl-beta-D-maltoside, and approximately 2 mg DtpT-His6 was purified by Ni2+-chelate affinity chromatography from 100 mg membrane protein. Purified DtpT-His6 was reconstituted unidirectionally into detergent-saturated formed liposomes, which were prepared from Escherichia coli phospholipid and egg phosphatidylcholine; the detergent was removed by adsorption to polystyrene beads. The highest uptake activities were obtained when DtpT was incorporated into liposomes that were treated with a low amount of n-dodecyl-beta-D-maltoside (onset of liposome solubilization). The uptake activity could be improved by addition of NaCl (200 mM) and lipids (2 mg/ml) during the solubilization, purification and reconstitution steps.     

Increased epidermal growth factor receptor expression in metaplastic bronchial epithelium

Epidermal growth factor receptor (EGFr) is expressed in human bronchial epithelial cells, and non-small cell lung cancers express increased EGFr. Squamous metaplasia of the bronchial epithelium occurs in chronic smokers and is considered an early premalignant change. In this study, EGFr expression was examined in biopsies of histologically normal and metaplastic bronchial tissues obtained from 69 smokers who were enrolled in a randomized placebo-controlled chemoprevention trial. This trial tested the effects of 6 months of treatment with 13-cis retinoic acid (13cRA) on bronchial metaplasia. EGFr expression was examined as a marker of bronchial metaplasia and response to 13cRA treatment. In bronchial biopsies obtained from patients in this study, EGFr expression was higher in metaplastic biopsies than in normal biopsies (P = 0.02). Smoking cessation during treatment correlated with reduced metaplasia (P < 0.001) and EGFr expression (P = 0.02), but multivariate analysis suggested that this effect of smoking cessation on EGFr expression was dependent upon reversal of bronchial metaplasia. 13cRA treatment did not alter EGFr expression (P = 0.23). Baseline EGFr expression levels in metaplastic biopsies did not predict metaplasia reversal. This study demonstrated that increased EGFr expression is a biomarker of bronchial metaplasia, but it did not support the hypothesis that EGFr is a biomarker of retinoid response in lung cancer chemoprevention trials.     

Endoscopic carpal tunnel release: a cadaveric study

Monoclonal antibodies against the irreversible alkylator N-ethyl-1-[2-(4-isothiocyanothienyl)]cyclohexylamine (ITCE) of the 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP) binding site of the N-methyl-D-aspartate receptor were raised. Each antibody was characterized in a competition enzyme-linked immunosorbent assay (ELISA) with a range of TCP analogs. It was found that each monoclonal antibody has a different affinity profile for the various TCP analogs. No correlation between the structure of the side chain groups of each compound and the selective affinities of the antibodies could be deduced, indicating that the overall affinity of the antibodies is determined by more than just the sum of the interaction forces with each ligand's functional groups. In addition to the possible identification of endogenous TCP-like compounds these antibodies could be used as a model to study the molecular interaction between drugs and their receptors' active sites.     

The impact of multi-frequency and forced disturbances upon drop size distributions in prilling

The dynamics of curved liquid jets, such as those emanating from wall of a porous cylinder rotating about its vertical axis, are of interest to industries employing the prilling process to manufacture particulate products such as fertilisers. Although many theoretical and experimental studies have been published to date, none have addressed how mechanical vibrations affect the dynamics. In this paper, the influence of multiple disturbance frequencies upon the jet dynamics (imparted by mechanical vibrations), is examined for the first time. The theoretical predictions, obtained using both linear and non-linear models, show a much better agreement with results obtained from pilot-scale experiments than have been obtained in previous studies. The use of additional forced disturbances to control the particle size is also considered.     

Technoeconomic analysis of biofuels: A wiki-based platform for lignocellulosic biorefineries

We present a process model for a lignocellulosic ethanol biorefinery that is open to the biofuels academic community. Beyond providing a series of static results, the wiki-based platform provides a dynamic and transparent tool for analyzing, exploring, and communicating the impact of process advances and alternatives for biofuels production. The model is available for download (at http://econ.jbei.org) and will be updated based on feedback from the community of experts in biofuel-related fields. By making the assumptions and performance metrics of this model transparent, we anticipate this tool can provide a consensus on the energy-related, environmental, and economic performance of lignocellulosic ethanol.     

A mössbauer study of zinc-iron intermediate phases and electrodeposited coatings

A Mössbauer study was made of all the single intermediate phases in the zinc-iron system. These phases were prepared by a heat-treatment method, and the Mössbauer transmission spectrum of each phase was recorded. The spectra were fitted on the basis of the crystal structure of each phase. The computer-fitted results were reported in terms of isomer shift, quadrupole splitting, and line width. These single-phase spectra were used as standards for the analysis of an electrodeposited zinc-iron alloy coating (11 wt pet Fe). The main phase detected in the coating was the δ phase, which was confirmed by X-ray diffraction analysis. The advantages of the Mössbauer spectroscopy technique in comparison with the X-ray diffraction method are discussed.