RP-HPLC/MS-APCI Analysis of Branched Chain TAG Prepared by Precursor-Directed Biosynthesis with <Emphasis Type="Italic">Rhodococcus</Emphasis><Emphasis Type="Italic">erythropolis</Emphasis>

Reversed phase liquid chromatography–atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/MS-APCI) was used to analyze both synthetic triacylglycerols (TAG) having 1–3 branched fatty acids (FA) in the molecule, and natural TAG prepared by precursor directed biosynthesis from valine, leucine and isoleucine and the corresponding branched short-chain acids in cultivations of Rhodococcus erythropolis. The technique made it possible to identify and quantify TAG differing in a single branched-chain FA. Altogether 11 TAG were synthesized, out of which 8 were synthesized stereospecifically. Branched- and straight-chain-TAG were separated and identified while TAG differing only in iso or anteiso FA could not be separated. The APCI mass spectra of iso-, anteiso- and straight-chain TAG were completely identical. The natural material was found to contain 19 TAG having at least one branched FA. Cultivation on six different substrates showed, apart from the presumed and common incorporation of precursors to iso-even, iso-odd and anteiso FA, also some unusual features such as an increase in the content of odd-FA after the addition of Val (attributed to catabolism of Val to propionate) or the appearance of branched monounsaturated FA. The two-sample paired t test, when applied to the TAG, showed that only the pair Val and isobutyrate differ in incorporation into FA—see, e.g. proportions of M/M/O and brM/brM/O (1.2:1.2 and 1.9:1.2, respectively). Also, incorporation of Val (isobutyrate) yielded only TAG having two branched FA in the molecule, whereas Leu and Ile (isovalerate and 2-methyl-butyrate) gave only TAG with a single branched FA in the molecule.     

Dynamics of Plasma and Urinary Extracellular DNA in Acute Kidney Injury

Early and reliable markers of acute kidney injury (AKI) are essential. One such candidate marker of tissue damage is extracellular DNA (ecDNA). The aim of our present study is to describe the unknown dynamics of ecDNA in an animal model of AKI. Glycerol-induced nephropathy was used to model AKI in adult male Wistar rats (n = 93). Blood and urine samples were collected 1, 3, and 24 h after model induction. Total ecDNA and its sub-cellular origin was assessed. In the plasma, total ecDNA and nuclear ecDNA were significantly increased in the AKI group already after 1 h (160% and 270%, respectively, p = 0.02 and p = 0.04). Both nuclear and mitochondrial ecDNA were higher after 3 h (180% and 170%, respectively, p = 0.002 and p = 0.005). Urinary ecDNA concentrations in the AKI group were significantly increased only 24 h after model induction (130% for total ecDNA, p = 0.009; 210% for nuclear ecDNA, p = 0.02; and 200% for mitochondrial ecDNA, p = 0.0009). Our results indicate that plasma ecDNA has the potential to serve as an early and sensitive, albeit non-specific marker of AKI. Further studies should elucidate the source of ecDNA and the dynamics of ecDNA in other animal models of AKI and patients with AKI.     

Microwave-assisted synthesis of carboxymethylcellulose – based polymeric surfactants

Summary Carboxymethylcellulose (CMC, DS_CM = 1) was partially hydrophobized in order to prepare polymeric surfactants by the transesterification reaction using the methyl ester of the fatty acid complex of rapeseed oil (MERO). The chemical modification was performed in different reaction media (i) DMF/TSA and (ii) H₂O/DMF with and without K₂CO₃ as catalyst, at various reaction conditions and using microwave radiation with controlled power as heating source. The obtained MERO-hydrophobized CMC (MH-CMC) comprising mixed fatty acyl esters were characterized by FT-IR and NMR spectroscopic techniques, which indicated a very low degree of esterification (DS < 0.1). The derivatives showed, in spite of moderate surface tension-lowering effects, excellent emulsifying activity for ‘oil in water’ type emulsions as well as good performance properties including washing power and antiredeposition efficiency. The results suggested that surface-active MH-CMC derivatives can be prepared under microwave heating at reaction times in the range of several minutes, what is a great advantage in comparison to transesterification reactions lasting up to 6 h at conventional heating. The novel CMC esters represent biodegradable polymeric surfactants with potential applications in manufacture of consumer products and in industrial processes.     

Of Coffee Shops and Parking Lots: Considering Matters of Space and Place in the Use of Public Wi-Fi

Wireless local area networks – or Wi-Fi networks – are proliferating in some societies. Our interest in this exploratory essay is to illustrate how ostensibly free, publicly-accessible Wi-Fi requires users to apply conventional understandings of space and place (particularly commercial spaces and places) as they make sense of some ambiguities about proper use in those places. We show, through an examination of the metaphorical terms used to describe Wi-Fi, how spatial notions are employed in an attempt to define ownership of the signal and rights to its use. We consider how place-behaviors require evaluation of legitimacy of users in public places and of hospitality of Wi-Fi providers. We observe that commercial interests underpin notions of ownership, legitimacy and hospitality of social actors in public places like coffee shops and parking lots. As researchers considering matters of participation in virtual places, we must first have some appreciation for the normative constraints and conventions that govern the commercial public places in which users access “free” Wi-Fi.     

The effects of drink-driving checkpoints on crashes—A meta-analysis

A meta-analysis has been conducted on the effects on crashes of DUI-checkpoints (DUI, driving under the influence). The results indicate that crashes involving alcohol are reduced by 17% at a minimum and that all crashes, independent of alcohol involvement, are reduced by about 10–15%. In a moderator analysis the effects of a number of factors that may affect the effectiveness of DUI-checkpoints were investigated by means of subgroup analyses and meta-regression. Those moderator variables that were found to be most relevant, are the time period studied, country, and study design. DUI-checkpoints were found to be most effective during the first half year. Australian checkpoints were found to be more effective than checkpoints in other countries. Smaller crash reductions were found in studies that have applied a control group than in other studies. Testing all drivers who are stopped at a checkpoint may improve the effectiveness of DUI-checkpoints. The results do not indicate that DUI-checkpoints have greater effects on more severe crashes or that the use of paid publicity improves the effectiveness. Most likely there are further factors that affect the effectiveness of DUI-checkpoints that could not be investigated in the present analysis.     

A congestion control framework for available bit rate service in ATM networks

Fair packet discarding (FPD) is a mechanism which provides incentives to users to co‐operate in congestion control, so that ATM networks can operate more efficiently. In this paper, we propose a simple congestion control framework consisting of a combination of FPD and ATM Forum's explicit‐rate flow control scheme. We show by simulations that this frame‐work achieves all objectives of congestion control: (1) control congestion, (2) achieve high user‐perceived throughput, (3) maintain fairness and (4) provide protection from misbehaving users. In addition, we equip this framework with two enhancements to improve efficiency, and reduce end‐to‐end delay. Copyright © 2002 John Wiley & Sons, Ltd.     

Estimation of the diffusion coefficient from sorption measurements

In this paper a procedure for the estimation of the diffusion coefficient for a sorption process from the measurements of the adsorbed amount is proposed. The experiments from which the data have been obtained are described and the numerical results are discussed.