Evaluation of matrix effects in metabolite profiling based on capillary liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry

The coupling of liquid chromatography to electrospray ionization quadrupole time-of-flight mass spectrometry can be a powerful tool for metabolomics, i.e., the comprehensive detection of low molecular weight compounds in biological systems. There have, however, been doubts about the feasibility and reliability of this approach, because LC-MS--especially with electrospray ionization--can be subject to matrix effects. We evaluated matrix effects for our metabolomics platform in three ways: (i) postextraction addition of a set of reference compounds to different complex biological matrixes to determine absolute and relative matrix effects, (ii) postcolumn infusion of two reference compounds, and (iii) mixing of two complex matrixes. Our data demonstrate that there are indeed significant absolute matrix effects when comparing highly divergent samples. However, relative matrix effects are negligible--unless extremely divergent matrixes are compared--and do not compromise the relative quantification that is aimed for in nontargeted metabolomics studies. In conclusion, employing LC-coupled ESI-QTOF-MS for metabolomics studies is feasible yet rigorous validation is necessary.     

Gold surface functionalization and patterning for specific immobilization of olfactory receptors carried by nanosomes

There is substantial interest in engineering solid supports to achieve functional immobilization of membrane receptors both for investigation of their biological function and for the development of novel biosensors. Three simple and practical strategies for immobilization of a human olfactory receptor carried by nanosomes are presented. The basis of the functionalization of solid gold surfaces is a self-assembled monolayer (SAM) containing biotinyl groups. Biotinyl groups are subsequently used to attach neutravidin and then biotinylated monoclonal antibody directed against the receptor to allow its specific grafting. Surface plasmon resonance technique is implemented for real-time monitoring of step-by-step surface functionalization and, in addition, for testing the functional response of immobilized olfactory receptors. We show that OR1740 is functional when immobilized via a tag attached to its C-terminus, but not via its N-terminus. Finally, we demonstrate that gold surfaces can be patterned by the SAMs tested using microcontact printing. AFM images of immobilized nanosomes onto a patterned surface suggest that small nanosomes flatten and fuse into larger vesicles but do not merge into a continuous layer. The whole study emphasizes the outstanding performances of the BAT/PEGAT SAM, which could be useful for developing on-a-chip sensor formats for membrane receptor investigations and use.     

In vitro digestion rate and resistant starch content of tortillas stored at two different temperatures

In vitro indicators of starch bioavailability were evaluated in freshly prepared maize tortillas and compared to those exhibited by 24, 48 or 72 h-stored samples. Storage took place either at room temperature (approx. 25 °C) or under refrigeration (4 °C). Potentially available starch (AS) content decreased from 670 g kg⁻¹ in the control tortilla to 583 g kg⁻¹ in 72 h-stored preparations. Concomitant increases in total resistant starch (RS) and retrograded resistant starch (RRS) were recorded upon storage. RRS content in 72 h-stored samples (35-39 g kg⁻¹) doubled that of freshly prepared tortillas. Changes in AS, RS and RRS were not affected by storage temperature. Both initial rate and final point of starch hydrolysis by pancreatic amylase were reduced in samples kept for 48 and 72 h, without influence of storage temperature. Storage length is suggested as a major determinant of the bioavailability of starch in tortillas.     

Particle concentrations and effectiveness of free-standing air filters in bedrooms of children with asthma in Detroit,Michigan

Asthma can be exacerbated by environmental factors including airborne particulate matter (PM) and environmental tobacco smoke (ETS). We report on a study designed to characterize PM levels and the effectiveness of filters on pollutant exposures of children with asthma. 126 households with an asthmatic child in Detroit, Michigan, were recruited and randomized into control or treatment groups. Both groups received asthma education; the latter also received a free-standing high efficiency air filter placed in the child’s bedroom. Information regarding the home, emission sources, and occupant activities was obtained using surveys administered to the child’s caregiver and a household inspection. Over a one week period, we measured PM, carbon dioxide (CO₂), environmental tobacco smoke (ETS) tracers, and air exchange rates (AERs). Filters were installed at midweek. Before filter installation, PM concentrations averaged 28 μg m⁻³, number concentrations averaged 70,777 and 1471 L⁻¹ in 0.3–1.0 and 1–5 μm size ranges, respectively, and the median CO₂ concentration was 1018 ppm. ETS tracers were detected in 23 of 38 homes where smoking was unrestricted and occupants included smokers and, when detected, PM concentrations were elevated by an average of 15 μg m⁻³. Filter use reduced PM concentrations by an average of 69–80%. Simulation models representing location conditions show that filter air flow, room volume and AERs are the key parameters affecting PM removal, however, filters can achieve substantial removal in even "worst" case applications. While PM levels in homes with asthmatic children can be high, levels can be dramatically reduced using filters.     

Kidney-Specific CAP1/Prss8-Deficient Mice Maintain ENaC-Mediated Sodium Balance through an Aldosterone Independent Pathway

The serine protease prostasin (CAP1/Prss8, channel-activating protease-1) is a confirmed in vitro and in vivo activator of the epithelial sodium channel ENaC. To test whether proteolytic activity or CAP1/Prss8 abundance itself are required for ENaC activation in the kidney, we studied animals either hetero- or homozygous mutant at serine 238 (S238A; Prss8^cat/+ and Prss8^cat/cat), and renal tubule-specific CAP1/Prss8 knockout (Prss8^PaxLC1) mice. When exposed to varying Na⁺-containing diets, no changes in Na⁺ and K⁺ handling and only minor changes in the expression of Na⁺ and K⁺ transporting protein were found in both models. Similarly, the α- or γENaC subunit cleavage pattern did not differ from control mice. On standard and low Na⁺ diet, Prss8^cat/+ and Prss8^cat/cat mice exhibited standard plasma aldosterone levels and unchanged amiloride-sensitive rectal potential difference indicating adapted ENaC activity. Upon Na⁺ deprivation, mice lacking the renal CAP1/Prss8 expression (Prss8^PaxLC1) exhibit significantly decreased plasma aldosterone and lower K⁺ levels but compensate by showing significantly higher plasma renin activity. Our data clearly demonstrated that the catalytic activity of CAP1/Prss8 is dispensable for proteolytic ENaC activation. CAP1/Prss8-deficiency uncoupled ENaC activation from its aldosterone dependence, but Na⁺ homeostasis is maintained through alternative pathways.     

Über die Nitril-Carboxamid-Umlagerung und die Heterocyclenbildung aus 2-Cyancyclohexenylharnstoff

The Nitrile Carboxamide Rearrangement and the Formation of Heterocycles via Cyano-cyclohexenyl-urea Anthranilic amide and cyanogen bromide form Cyano-phenyl-urea ( 7 ) via Nitrile Carboxamide Rearrangement. Cyclisation of cyano-cyclohexenyl-urea ( 4 ) yields 4-amino-2,3,5,6,7,8-hexahydroquinazolin-2-one ( 10 ). 4 and amines form N-cyano-cyclohexenyl-N'-alkyl-ureas ( 11a–e ) or 3-alkyl-4-amino-hexahydroquinazolin-2-ones ( 12a–g ). 4 and α-aminoacids yield octahydro-imidazolo-quinazolindiones ( 14a–b ). Oxo-cyclohexane-2-carboxamide ( 1 ) and amino benzimidazole form hexahydrobenzimidazo-quinazolinone 17 .     

State of the Art in Dense Monocular Non-Rigid 3D Reconstruction

3D reconstruction of deformable (or non-rigid) scenes from a set of monocular 2D image observations is a long-standing and actively researched area of computer vision and graphics. It is an ill-posed inverse problem, since—without additional prior assumptions—it permits infinitely many solutions leading to accurate projection to the input 2D images. Non-rigid reconstruction is a foundational building block for downstream applications like robotics, AR/VR, or visual content creation. The key advantage of using monocular cameras is their omnipresence and availability to the end users as well as their ease of use compared to more sophisticated camera set-ups such as stereo or multi-view systems. This survey focuses on state-of-the-art methods for dense non-rigid 3D reconstruction of various deformable objects and composite scenes from monocular videos or sets of monocular views. It reviews the fundamentals of 3D reconstruction and deformation modeling from 2D image observations. We then start from general methods—that handle arbitrary scenes and make only a few prior assumptions—and proceed towards techniques making stronger assumptions about the observed objects and types of deformations (e.g. human faces, bodies, hands, and animals). A significant part of this STAR is also devoted to classification and a high-level comparison of the methods, as well as an overview of the datasets for training and evaluation of the discussed techniques. We conclude by discussing open challenges in the field and the social aspects associated with the usage of the reviewed methods.     

Bildung von Azoolefinen durch Umsetzung von Hydrazinen mit Amino-hydroxy-hydrobenzoxazol

About the Reaction between Hydrazines and Aminohydroxy-hydrobenzoxazol. Synthesis of Azoolefines By the reaction of 1-hydroxy-2-oxocyclohexane-carboxamide ( 1 ) with cyanamide 2-amino-7a-carbamoyl-3a-hydroxy-3a,4a,5,6,7,7a-hexahydrobenzoxazole ( 2 ) is formed. Compound 2 and arylhydrazine-hydrochloride yield 1-carbamoyl-2-arylazocyclohex-1-ene ( 4a , b ). In morpholine azocompounds 4a , b rearrange to hydrazones 5a , b . Compound 2 and hydrazine yield 4-(2-carbamoyl-cyclohexyl)-semicarbazide ( 10 ), 10 forms perhydroquinazoline-2,4-dione ( 11 ) by oxidation with iodine. 2 and cyanic acid yield the urea derivative 12 . 2 and arylamine-hydrochloride afford the 2-arylamino-3a-hydroxy-7a-carbamoyl-hexahydrobenzoxazoles 13a , b . By fragmentation and “Dimroth-rearrangement” of 2 tetrahydrobenzoimidazolone, ( 14 ) is formed, 12 gives 1-carbamoyl-tetrahydrobenzoimidazolone ( 15 ). 2 and m-nitrobenzaldehyde yield “Schiff-base” 16 . 2 and hydroxylamine sulphate form 2′-amino-2-hydroximino-cyclohexane-spiro-5′-oxazolin-4′-one ( 18 ) 18 and phenylhydrazine hydrochloride yield 1-phenylazo-2-ureido-carboxy-cyclohex-1-ene ( 19 ).     

Feinstruktur und Hyperfeinstruktur von klinisch verwendeter Hydroxyethylstärke

Fine Structure and Hyperfine Structure of Clinically Applied Hydroxyethyl Starch. The Mark-Houwink-relationships for different samples of clinically used hydroxyethyl starches were established by multi-detection HPGPC. In combination with the degree of branching, the degrees of substitution DS and the molar substitution MS for the different molecular regions were measured by gas chromatographic methylation analysis. Within the molecular regions of non reducing anhydroglucose units, branching units and linear units we found characteristic differences. For hydroxyethyl starches which were prepared from enzymatically hydrolyzed waxy maize starch by α-Amylase, we found a significantly higher degree of branching than for samples prepared by acid hydrolysis. The clinical relevance of these results is discussed.     

Zur Bromierung des Cyclohexanon-2-carbonsäureamids

The Bromination of Cyclohexanone-2-carboxamide Cyclohexanone-2-carboxamide with bromine forms 6-bromo-cyclohexanone-2-carboxamide ( 2 ) or 2-bromo-cyclohexanone-2-carboxamide ( 3 ). Via Faworski-rearrangement the reaction of 2 and ammonia or amines gives trans-cyclopentanedicarboxamides ( 5a – f ). 3 and thiourea form the aminothiazole derivative 6 . Pyridinium salt 7 is formed by reaction of 2 and pyridine. 7 and phenylhydrazine form the phenyl-indazolonoyl-hydrazine 8. 1 and sodiumhypochlorite yield 2-hydroxy-cyclohexanone-2-carboxamide ( 9 ).