60 results on '"Wehr R"'
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2. A rapid high-precision analytical method for triple oxygen isotope analysis of CO 2 gas using tunable infrared laser direct absorption spectroscopy.
- Author
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Perdue N, Sharp Z, Nelson D, Wehr R, and Dyroff C
- Abstract
Rationale: The simultaneous analysis of the three stable isotopes of oxygen-triple oxygen isotope analysis-has become an important analytical technique in natural sciences. Determination of the abundance of the rare
17 O isotope in CO2 gas using magnetic sector isotope ratio mass spectrometry is complicated by the isobaric interference of17 O by13 C (13 C16 O16 O and12 C16 O17 O, both have mass 45 amu). A number of analytical techniques have been used to measure the17 O/16 O ratio of CO2 gas. They either are time consuming and technically challenging or have limited precision. A rapid and precise alternative to the available analytical methods is desirable., Methods: We present the results of triple oxygen isotope analyses using an Aerodyne tunable infrared laser direct absorption spectroscopy (TILDAS) CO2 analyzer configured for16 O,17 O, and18 O combined with a custom gas inlet system. We evaluate the sensitivity of our results to a number of parameters. CO2 samples with a wide range of δ18 O values (from -9.28‰ to 39.56‰) were measured and compared to results using the well-established fluorination-gas source mass spectrometry method., Results: The TILDAS system has a precision (standard error, 2σ) of better than ±0.03‰ for δ18 O and ±10 per meg for Δ'17 O values, equivalent to the precision of previous analytical methods. Samples as small as 3 μmol CO2 (equivalent to 300 μg CaCO3 ) can be analyzed with a total analysis time of ~30 min., Conclusions: We have successfully developed an analytical technique for the simultaneous determination of the δ17 O and δ18 O values of CO2 gas. The precision is equal to or better than that of existing techniques, with no additional chemical treatments required. Analysis time is rapid, and the system is easily automated so that large numbers of samples can be analyzed with minimal effort., (© 2022 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.)- Published
- 2022
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3. Adverse Drug Reactions at Nonelective Hospital Admission in Children and Adolescents: Comparison of 4 Causality Assessment Methods.
- Author
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Neininger MP, Wehr R, Kiesel LM, Neubert A, Kiess W, Bertsche A, and Bertsche T
- Subjects
- Adolescent, Child, Hospitalization, Hospitals, Humans, Reproducibility of Results, Adverse Drug Reaction Reporting Systems, Drug-Related Side Effects and Adverse Reactions diagnosis, Drug-Related Side Effects and Adverse Reactions epidemiology, Drug-Related Side Effects and Adverse Reactions etiology
- Abstract
Objectives: This study aimed to compare assessment methods to determine adverse drug reactions (ADRs) at nonelective hospital admission in pediatric patients, to investigate the interrater reliability of assessment methods in pediatric care, and to analyze symptoms related to ADRs and (suicidal) drug intoxications., Methods: For 1 year, the medical records of nonelective patients admitted to a university pediatric department were evaluated for potential ADRs using 4 assessments methods by 1 experienced rater. Krippendorff α was calculated from a sample of 14 patients evaluated by 4 experienced raters to determine interrater reliability., Results: In 1831 nonelective hospital admissions, 63.4% (1161 of 1831) of patients had received at least one drug before admission. We found a potential causal relationship between drugs and symptoms documented at admission and thus potential ADRs according to Naranjo in 23.3% (271 of 1161) of those patients, World Health Organization - Uppsala Monitoring Centre (WHO-UMC) in 22.5% (261 of 1161), Koh in 21.7% (252 of 1161), and Begaud in 16.5% (192 of 1161). The probability rating of the potential causal relationships varied considerably between the methods (Naranjo-Begaud, P < 0.01; Naranjo-Koh, P < 0.001; Koh-Begaud, P < 0.01; Begaud-WHO-UMC, P < 0.01). Acceptable interrater reliability (α ≥ 0.667) was only obtained for WHO-UMC (α = 0.7092). The most frequently identified definite ADR was sedation in 1.5% of all nonelective patients with medication before hospital admission. In 1.2% (22 of 1831) of all nonelective admissions, we found drug intoxications with suicidal intent., Conclusions: The assessment methods showed a high variability in the determination of a potential causal relationship between drug and documented symptom, in the classification of the probability of ADRs, and suboptimal interrater reliability. Thus, their feasibility in pediatric patients is limited., Competing Interests: The authors disclose no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)
- Published
- 2022
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4. Tailoring a Solvent-Assisted Method for Solid-Supported Hybrid Lipid-Polymer Membranes.
- Author
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Di Leone S, Kyropoulou M, Köchlin J, Wehr R, Meier WP, and Palivan CG
- Subjects
- Lipid Bilayers chemistry, Microscopy, Atomic Force, Phospholipids chemistry, Solvents, Membranes, Artificial, Polymers chemistry
- Abstract
Combining amphiphilic block copolymers and phospholipids opens new opportunities for the preparation of artificial membranes. The chemical versatility and mechanical robustness of polymers together with the fluidity and biocompatibility of lipids afford hybrid membranes with unique properties that are of great interest in the field of bioengineering. Owing to its straightforwardness, the solvent-assisted method (SA) is particularly attractive for obtaining solid-supported membranes. While the SA method was first developed for lipids and very recently extended to amphiphilic block copolymers, its potential to develop hybrid membranes has not yet been explored. Here, we tailor the SA method to prepare solid-supported polymer-lipid hybrid membranes by combining a small library of amphiphilic diblock copolymers poly(dimethyl siloxane)-poly(2-methyl-2-oxazoline) and poly(butylene oxide)- block -poly(glycidol) with phospholipids commonly found in cell membranes including 1,2-dihexadecanoyl- sn -glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphoethanolamine, sphingomyelin, and 1,2-dioleoyl- sn -glycero-3-phosphoethanolamine- N -(glutaryl). The optimization of the conditions under which the SA method was applied allowed for the formation of hybrid polymer-lipid solid-supported membranes. The real-time formation and morphology of these hybrid membranes were evaluated using a combination of quartz crystal microbalance and atomic force microscopy. Depending on the type of polymer-lipid combination, significant differences in membrane coverage, formation of domains, and quality of membranes were obtained. The use of the SA method for a rapid and controlled formation of solid-supported hybrid membranes provides the basis for developing customized artificial hybrid membranes.
- Published
- 2022
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5. Detecting forest response to droughts with global observations of vegetation water content.
- Author
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Konings AG, Saatchi SS, Frankenberg C, Keller M, Leshyk V, Anderegg WRL, Humphrey V, Matheny AM, Trugman A, Sack L, Agee E, Barnes ML, Binks O, Cawse-Nicholson K, Christoffersen BO, Entekhabi D, Gentine P, Holtzman NM, Katul GG, Liu Y, Longo M, Martinez-Vilalta J, McDowell N, Meir P, Mencuccini M, Mrad A, Novick KA, Oliveira RS, Siqueira P, Steele-Dunne SC, Thompson DR, Wang Y, Wehr R, Wood JD, Xu X, and Zuidema PA
- Subjects
- Forests, Plant Leaves, Trees, Xylem, Droughts, Ecosystem
- Abstract
Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more. Unlike water potential, which requires demanding in situ measurements, VWC can be retrieved from remote sensing measurements, particularly at microwave frequencies using radar and radiometry. Here, we highlight key frontiers through which VWC has the potential to significantly increase our understanding of forest responses to water stress. To validate remote sensing observations of VWC at landscape scale and to better relate them to data assimilation model parameters, we introduce an ecosystem-scale analog of the pressure-volume curve, the non-linear relationship between average leaf or branch water potential and water content commonly used in plant hydraulics. The sources of variability in these ecosystem-scale pressure-volume curves and their relationship to forest response to water stress are discussed. We further show to what extent diel, seasonal, and decadal dynamics of VWC reflect variations in different processes relating the tree response to water stress. VWC can also be used for inferring belowground conditions-which are difficult to impossible to observe directly. Lastly, we discuss how a dedicated geostationary spaceborne observational system for VWC, when combined with existing datasets, can capture diel and seasonal water dynamics to advance the science and applications of global forest vulnerability to future droughts., (© 2021 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)
- Published
- 2021
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6. Fully amorphous atactic and isotactic block copolymers and their self-assembly into nano- and microscopic vesicles.
- Author
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Wehr R, Dos Santos EC, Muthwill MS, Chimisso V, Gaitzsch J, and Meier W
- Abstract
The introduction of chirality into aqueous self-assemblies by employing isotactic block copolymers (BCPs) is an emerging field of interest as it promises special membrane properties of polymersomes not accessible by atactic BCPs. However, isotactic BCPs typically exhibit crystalline behaviour, inducing high membrane stiffness and limiting their applicability in systems involving membrane proteins or sensitive cargo. In this study, an isotactic yet fully amorphous BCP is introduced which overcomes these limitations. Three BCPs composed of poly(butylene oxide)- block -poly(glycidol) (PBO- b -PG), differing solely in their tacticities ( R / S , R and S ), were synthesised and characterised regarding their structural, optical and thermal properties. Their self-assembly into homogenous phases of nanoscopic polymersomes (referred to as small unilamellar vesicles, SUVs) was analysed, revealing stability differences between SUVs composed of the different BCPs. Additionally, microscopic giant unilamellar vesicles (GUVs) were prepared by double emulsion microfluidics. Only the atactic BCP formed GUVs which were stable over several hours, whereas GUVs composed of isotactic BCPs ruptured within several minutes after formation. The ability of atactic PBO- b -PG to form microreactors was elucidated by reconstituting the membrane protein OmpF in the GUV membrane by microfluidics and performing an enzyme reaction inside its lumen. The system presented here serves as platform to design versatile vesicles with flexible membranes composed of atactic or isotactic BCPs. Hence, they allow for the introduction of chirality into nano- or microreactors which is a yet unstudied field and could enable special biotechonological applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)
- Published
- 2021
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7. Catalytic polymersomes to produce strong and long-lasting bioluminescence.
- Author
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Meyer CE, Craciun I, Schoenenberger CA, Wehr R, and Palivan CG
- Subjects
- Catalysis, Luciferases, Luminescent Measurements
- Abstract
Here, we introduce an artificial bioluminescent nanocompartment based on the encapsulation of light-producing enzymes, luciferases, inside polymersomes. We exploit nanocompartmentalization to enhance luciferase stability in a cellular environment but also to positively modulate enzyme kinetics to achieve a long-lasting glow type signal. These features pave the way for expanding bioluminescence to nanotechnology-based applications.
- Published
- 2021
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8. Deepening the insight into poly(butylene oxide)- block -poly(glycidol) synthesis and self-assemblies: micelles, worms and vesicles.
- Author
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Wehr R, Gaitzsch J, Daubian D, Fodor C, and Meier W
- Abstract
Aqueous self-assembly of amphiphilic block copolymers is studied extensively for biomedical applications like drug delivery and nanoreactors. The commonly used hydrophilic block poly(ethylene oxide) (PEO), however, suffers from several drawbacks. As a potent alternative, poly(glycidol) (PG) has gained increasing interest, benefiting from its easy synthesis, high biocompatibility and flexibility as well as enhanced functionality compared to PEO. In this study, we present a quick and well-controlled synthesis of poly(butylene oxide)- block -poly(glycidol) (PBO- b -PG) amphiphilic diblock copolymers together with a straight-forward self-assembly protocol. Depending on the hydrophilic mass fraction of the copolymer, nanoscopic micelles, worms and polymersomes were formed as well as microscopic giant unilamellar vesicles. The particles were analysed regarding their size and shape, using dynamic and static light scattering, TEM and Cryo-TEM imaging as well as confocal laser scanning microscopy. We have discovered a strong dependence of the formed morphology on the self-assembly method and show that only solvent exchange leads to the formation of homogenous phases. Thus, a variety of different structures can be obtained from a highly flexible copolymer, justifying a potential use in biomedical applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)
- Published
- 2020
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9. Polymer-Lipid Hybrid Membranes as a Model Platform to Drive Membrane-Cytochrome c Interaction and Peroxidase-like Activity.
- Author
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Di Leone S, Avsar SY, Belluati A, Wehr R, Palivan CG, and Meier W
- Subjects
- Lipids, Oxidation-Reduction, Peroxidases, Cytochromes c metabolism, Polymers
- Abstract
Controllable attachment of proteins to material surfaces is very attractive for many applications including biosensors, bioengineered scaffolds or drug screening. Especially, redox proteins have received considerable attention as a model system not only to understand the mechanism of electron transfer in biological systems, but also the development of novel biosensors. However, current research attempts suffer from denaturation of the protein after its attachment to solid substrates. Here, we present how lipid, polymer and hybrid membranes based on mixtures of lipids and copolymers on a solid support provide a more favorable environment to drive selective and functional attachment of a model redox protein, cytochrome c (cyt c ). Polymer membranes provided chemical versatility to support covalent attachment of cyt c , whereas lipid membranes provided flexibility and biocompatibility to support insertion of cyt c through its hydrophobic part. Hybrid membranes combine the most promising characteristics of both lipids and polymers and allowed attachment of cyt c with both covalent attachment and insertion driven by hydrophobic interactions. We then investigated the effect of different attachment strategies on the accessibility and peroxidase-like activity of cyt c , in the presence of different membranes. The real-time combination of cyt c with the planar membranes was investigated by quartz crystal microbalance with dissipation. It was possible to selectively drive the insertion of cyt c into a specific lipid domain of hybrid membranes. In addition, protein accessibility and its functionality were dependent on the specificity of the combination strategy: covalent conjugation of cyt c to polymer and hybrid membranes promoted higher accessibility and supported higher peroxidase-like activity. Taking together, the combination of biomolecules with planar membranes can be modulated in such a way to improve the accessibility of the biomolecules and their resulting functionality for the development of efficient "active surfaces".
- Published
- 2020
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10. The pharmacokinetics and metabolism of diclofenac in chimeric humanized and murinized FRG mice.
- Author
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Wilson CE, Dickie AP, Schreiter K, Wehr R, Wilson EM, Bial J, Scheer N, Wilson ID, and Riley RJ
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- Animals, Anti-Inflammatory Agents, Non-Steroidal blood, Anti-Inflammatory Agents, Non-Steroidal urine, Area Under Curve, Bile metabolism, Biotransformation, Chimera blood, Chimera urine, Diclofenac blood, Diclofenac urine, Feces chemistry, Half-Life, Humans, Male, Mice, Mice, Inbred C57BL, Species Specificity, Anti-Inflammatory Agents, Non-Steroidal pharmacokinetics, Chimera metabolism, Diclofenac pharmacokinetics
- Abstract
The pharmacokinetics of diclofenac were investigated following single oral doses of 10 mg/kg to chimeric liver humanized and murinized FRG and C57BL/6 mice. In addition, the metabolism and excretion were investigated in chimeric liver humanized and murinized FRG mice. Diclofenac reached maximum blood concentrations of 2.43 ± 0.9 µg/mL (n = 3) at 0.25 h post-dose with an AUC
inf of 3.67 µg h/mL and an effective half-life of 0.86 h (n = 2). In the murinized animals, maximum blood concentrations were determined as 3.86 ± 2.31 µg/mL at 0.25 h post-dose with an AUCinf of 4.94 ± 2.93 µg h/mL and a half-life of 0.52 ± 0.03 h (n = 3). In C57BL/6J mice, mean peak blood concentrations of 2.31 ± 0.53 µg/mL were seen 0.25 h post-dose with a mean AUCinf of 2.10 ± 0.49 µg h/mL and a half-life of 0.51 ± 0.49 h (n = 3). Analysis of blood indicated only trace quantities of drug-related material in chimeric humanized and murinized FRG mice. Metabolic profiling of urine, bile and faecal extracts revealed a complex pattern of metabolites for both humanized and murinized animals with, in addition to unchanged parent drug, a variety of hydroxylated and conjugated metabolites detected. The profiles in humanized mice were different to those of both murinized and wild-type animals, e.g., a higher proportion of the dose was detected in the form of acyl glucuronide metabolites and much reduced amounts as taurine conjugates. Comparison of the metabolic profiles obtained from the present study with previously published data from C57BL/6J mice and humans revealed a greater, though not complete, match between chimeric humanized mice and humans, such that the liver humanized FRG model may represent a model for assessing the biotransformation of such compounds in humans.- Published
- 2018
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11. Cationic disulfide-functionalized worm gels.
- Author
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Ratcliffe LPD, Bentley KJ, Wehr R, Warren NJ, Saunders BR, and Armes SP
- Abstract
The recent development of polymerization-induced self-assembly (PISA) has facilitated the rational synthesis of a range of diblock copolymer worms, which hitherto could only be prepared via traditional post-polymerization processing in dilute solution. Herein we explore a new synthetic route to aqueous dispersions of cationic disulfide-functionalized worm gels. This is achieved via the PISA synthesis of poly[(glycerol monomethacrylate- stat -glycidyl methacrylate)]- block -poly(2-hydroxypropyl methacrylate) (P(GMA- stat -GlyMA)-PHPMA) block copolymer worms via reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization of HPMA. A water-soluble reagent, cystamine, is then reacted with the pendent epoxy groups located within the P(GMA- stat -GlyMA) stabilizer chains to introduce disulfide functionality, while simultaneously conferring cationic character via formation of secondary amine groups. Moreover, systematic variation of the cystamine/epoxy molar ratio enables either chemically cross-linked worm gels or physical (linear) primary amine-functionalized disulfide-based worm gels to be obtained. These new worm gels were characterized using gel permeation chromatography,
1 H NMR spectroscopy, transmission electron microscopy, dynamic light scattering, aqueous electrophoresis and rheology. In principle, such hydrogels may offer enhanced mucoadhesive properties.- Published
- 2017
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12. The pharmacokinetics and metabolism of lumiracoxib in chimeric humanized and murinized FRG mice.
- Author
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Dickie AP, Wilson CE, Schreiter K, Wehr R, Wilson EM, Bial J, Scheer N, Wilson ID, and Riley RJ
- Subjects
- Animals, Diclofenac blood, Diclofenac pharmacokinetics, Humans, Male, Mice, Mice, Inbred C57BL, Species Specificity, Chimera blood, Cyclooxygenase 2 Inhibitors blood, Cyclooxygenase 2 Inhibitors pharmacokinetics, Diclofenac analogs & derivatives
- Abstract
The pharmacokinetics and metabolism of lumiracoxib were studied, after administration of single 10mg/kg oral doses to chimeric liver-humanized and murinized FRG mice. In the chimeric humanized mice, lumiracoxib reached peak observed concentrations in the blood of 1.10±0.08μg/mL at 0.25-0.5h post-dose with an AUC
inf of 1.74±0.52μgh/mL and an effective half-life for the drug of 1.42±0.72h (n=3). In the case of the murinized animals peak observed concentrations in the blood were determined as 1.15±0.08μg/mL at 0.25h post-dose with an AUCinf of 1.94±0.22μgh/mL and an effective half-life of 1.28±0.02h (n=3). Analysis of blood indicated only the presence of unchanged lumiracoxib. Metabolic profiling of urine, bile and faecal extracts revealed a complex pattern of metabolites for both humanized and murinized animals with, in addition to unchanged parent drug, a variety of hydroxylated and conjugated metabolites detected. The profiles obtained in humanized mice were different compared to murinized animals with e.g., a higher proportion of the dose detected in the form of acyl glucuronide metabolites and much reduced amounts of taurine conjugates. Comparison of the metabolic profiles obtained from the present study with previously published data from C57bl/6J mice and humans, revealed a greater though not complete match between chimeric humanized mice and humans, such that the liver-humanized FRG model may represent a useful approach to assessing the biotransformation of such compounds in humans., (Copyright © 2017 Elsevier Inc. All rights reserved.)- Published
- 2017
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13. Lumiracoxib metabolism in male C57bl/6J mice: characterisation of novel in vivo metabolites.
- Author
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P Dickie A, Wilson CE, Schreiter K, Wehr R, D Wilson I, and Riley R
- Subjects
- Animals, Diclofenac metabolism, Mice, Mice, Inbred C57BL, Cyclooxygenase 2 Inhibitors metabolism, Diclofenac analogs & derivatives
- Abstract
1. The pharmacokinetics and metabolism of lumiracoxib in male C57bl/6J mice were investigated following a single oral dose of 10 mg/kg. 2. Lumiracoxib achieved peak observed concentrations in the blood of 1.26 + 0.51 μg/mL 0.5 h (0.5-1.0) post-dose with an AUC
inf of 3.48 + 1.09 μg h/mL. Concentrations of lumiracoxib then declined with a terminal half-life of 1.54 + 0.31 h. 3. Metabolic profiling showed only the presence of unchanged lumiracoxib in blood by 24 h, while urine, bile and faecal extracts contained, in addition to the unchanged parent drug, large amounts of hydroxylated and conjugated metabolites. 4. No evidence was obtained in the mouse for the production of the downstream products of glutathione conjugation such as mercapturates, suggesting that the metabolism of the drug via quinone-imine generating pathways is not a major route of biotransformation in this species. Acyl glucuronidation appeared absent or a very minor route. 5. While there was significant overlap with reported human metabolites, a number of unique mouse metabolites were detected, particularly taurine conjugates of lumiracoxib and its oxidative metabolites.- Published
- 2017
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14. Partitioning controls on Amazon forest photosynthesis between environmental and biotic factors at hourly to interannual timescales.
- Author
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Wu J, Guan K, Hayek M, Restrepo-Coupe N, Wiedemann KT, Xu X, Wehr R, Christoffersen BO, Miao G, da Silva R, de Araujo AC, Oliviera RC, Camargo PB, Monson RK, Huete AR, and Saleska SR
- Subjects
- Plant Leaves, Seasons, Trees, Ecosystem, Forests, Photosynthesis
- Abstract
Gross ecosystem productivity (GEP) in tropical forests varies both with the environment and with biotic changes in photosynthetic infrastructure, but our understanding of the relative effects of these factors across timescales is limited. Here, we used a statistical model to partition the variability of seven years of eddy covariance-derived GEP in a central Amazon evergreen forest into two main causes: variation in environmental drivers (solar radiation, diffuse light fraction, and vapor pressure deficit) that interact with model parameters that govern photosynthesis and biotic variation in canopy photosynthetic light-use efficiency associated with changes in the parameters themselves. Our fitted model was able to explain most of the variability in GEP at hourly (R
2 = 0.77) to interannual (R2 = 0.80) timescales. At hourly timescales, we found that 75% of observed GEP variability could be attributed to environmental variability. When aggregating GEP to the longer timescales (daily, monthly, and yearly), however, environmental variation explained progressively less GEP variability: At monthly timescales, it explained only 3%, much less than biotic variation in canopy photosynthetic light-use efficiency, which accounted for 63%. These results challenge modeling approaches that assume GEP is primarily controlled by the environment at both short and long timescales. Our approach distinguishing biotic from environmental variability can help to resolve debates about environmental limitations to tropical forest photosynthesis. For example, we found that biotically regulated canopy photosynthetic light-use efficiency (associated with leaf phenology) increased with sunlight during dry seasons (consistent with light but not water limitation of canopy development) but that realized GEP was nonetheless lower relative to its potential efficiency during dry than wet seasons (consistent with water limitation of photosynthesis in given assemblages of leaves). This work highlights the importance of accounting for differential regulation of GEP at different timescales and of identifying the underlying feedbacks and adaptive mechanisms., (© 2016 John Wiley & Sons Ltd.)- Published
- 2017
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15. Seasonality of temperate forest photosynthesis and daytime respiration.
- Author
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Wehr R, Munger JW, McManus JB, Nelson DD, Zahniser MS, Davidson EA, Wofsy SC, and Saleska SR
- Subjects
- Atmosphere chemistry, Carbon Dioxide metabolism, Cell Respiration radiation effects, Climate, Darkness, Plant Leaves cytology, Plant Leaves metabolism, Plant Leaves radiation effects, Time Factors, Trees cytology, Trees growth & development, Water metabolism, Forests, Photosynthesis radiation effects, Seasons, Sunlight, Trees metabolism, Trees radiation effects
- Abstract
Terrestrial ecosystems currently offset one-quarter of anthropogenic carbon dioxide (CO2) emissions because of a slight imbalance between global terrestrial photosynthesis and respiration. Understanding what controls these two biological fluxes is therefore crucial to predicting climate change. Yet there is no way of directly measuring the photosynthesis or daytime respiration of a whole ecosystem of interacting organisms; instead, these fluxes are generally inferred from measurements of net ecosystem-atmosphere CO2 exchange (NEE), in a way that is based on assumed ecosystem-scale responses to the environment. The consequent view of temperate deciduous forests (an important CO2 sink) is that, first, ecosystem respiration is greater during the day than at night; and second, ecosystem photosynthetic light-use efficiency peaks after leaf expansion in spring and then declines, presumably because of leaf ageing or water stress. This view has underlain the development of terrestrial biosphere models used in climate prediction and of remote sensing indices of global biosphere productivity. Here, we use new isotopic instrumentation to determine ecosystem photosynthesis and daytime respiration in a temperate deciduous forest over a three-year period. We find that ecosystem respiration is lower during the day than at night-the first robust evidence of the inhibition of leaf respiration by light at the ecosystem scale. Because they do not capture this effect, standard approaches overestimate ecosystem photosynthesis and daytime respiration in the first half of the growing season at our site, and inaccurately portray ecosystem photosynthetic light-use efficiency. These findings revise our understanding of forest-atmosphere carbon exchange, and provide a basis for investigating how leaf-level physiological dynamics manifest at the canopy scale in other ecosystems.
- Published
- 2016
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16. [Detection of Coxiella burnetii in dairy cattle bulk tank milk and single tank milk samples by confirmatory testing].
- Author
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Hilbert A, Andres T, Werner R, Wehr R, Fröhlich A, Conraths FJ, and Henning K
- Subjects
- Animals, Antibodies, Bacterial analysis, Bacterial Typing Techniques standards, Cattle, Female, Bacterial Typing Techniques methods, Coxiella burnetii isolation & purification, Dairying methods, Milk microbiology
- Abstract
Q fever is a worldwide zoonotic disease caused by the pathogen Coxiella (C.) burnetii. A wide range of animal species is susceptible to this intracellular bacterium with great importance in ruminants. Human infections occur mainly by airborne transmission. C burnetii was detected in animal products such as raw milk, raw-milk cheese and butter prepared from raw milk as well as in the meat of infected animals. In cattle milk, the pathogen was detected up to 13 months after calving. The risk of human foodborne C. Burnetii infection is still considered to be low, but cannot be completely ruled out and remains under discussion. The aim of this study was to compare different laboratory diagnostic methods for C. burnetii in milk sample. The bulk tank and individual milk samples were sent and studied at the National Reference Laboratory for Q-fever in the context of confirmatory laboratory testing after clinical suspicion or retesting of previously antibody detection was in the analysis of 888 individual milk samples a match of 93.3% (Cohen-kappa). A total of 173 bulk milk samples and 2,807 individual milk samples from bovine herds for the presence of C. burnetii DNA and antibodies were tested against the pathogen. The pathogen was detected in 62.5% of the bulk milk samples and up to 60% in individual milk samples. The highest proportion of positive bulk milks was determined as 68.3% in 2012. In individual milk samples, the highest proportion of seropositive samples was 62.2%.
- Published
- 2015
17. Mitochondrial DNA depletion in rat liver induced by fosalvudine tidoxil, a novel nucleoside reverse transcriptase inhibitor prodrug.
- Author
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Venhoff AC, Lebrecht D, Reuss FU, Heckl-Ostreicher B, Wehr R, Walker UA, and Venhoff N
- Subjects
- Animals, Didanosine pharmacology, Male, Polymerase Chain Reaction, Rats, Rats, Sprague-Dawley, Zidovudine pharmacology, DNA, Mitochondrial metabolism, Lipids pharmacology, Liver drug effects, Liver metabolism, Reverse Transcriptase Inhibitors pharmacology, Zidovudine analogs & derivatives
- Abstract
Fosalvudine tidoxil is a prodrug derived from the nucleoside reverse transcriptase inhibitor 3-deoxy-3-fluorothymidine (FLT; alovudine). FLT effectively inhibits resistant human immunodeficiency virus type 1, but its clinical development was stopped due to bone marrow and liver toxicity. In this study, we examined the long-term in vivo effects of fosalvudine tidoxil on the mitochondrial DNA (mtDNA) contents in rats. Sprague-Dawley rats received fosalvudine tidoxil (15, 40, or 100 mg/kg of body weight/day) by oral gavage during a period of 8 weeks. Didanosine (100 mg/kg/day) was used as a positive control for mitochondrial toxicity. mtDNA levels in liver, gastrocnemius muscle, sciatic nerve, and inguinal fat pad tissues were quantified by real-time PCR. In hepatic mitochondria, fosalvudine tidoxil induced significant mtDNA depletion. At doses of 15, 40, and 100 mg/kg, the mean hepatic mtDNA values were 62, 64, and 47% of control values, respectively. Rats exposed to 100 mg/kg of fosalvudine tidoxil, unlike all other groups, had slightly elevated levels of glutamate pyruvate transaminase in sera. Didanosine induced a loss of mtDNA (to 48% of the control level) similar to that induced by fosalvudine tidoxil. mtDNA levels in skeletal, neural, and adipose tissues in the negative control and treatment groups were similar. Our results suggest that fosalvudine tidoxil induces mitochondrial hepatotoxicity and that this effect warrants scrutiny in clinical trials.
- Published
- 2009
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18. The line shape problem in the near-infrared spectrum of self-colliding CO2 molecules: experimental investigation and test of semiclassical models.
- Author
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Casa G, Wehr R, Castrillo A, Fasci E, and Gianfrani L
- Abstract
An intensity-stabilized diode laser absorption spectrometer was developed and used to perform a highly accurate study of the line shape of CO(2) absorption lines, in the spectral region around 5000 cm(-1), belonging to the nu(1) + 2nu(2)(0) + nu(3) combination band, at a temperature of 296.00 K. Standard and complex semiclassical models, including Dicke narrowing and speed-dependent broadening effects, were applied, tested, and compared in the pressure range between 0.7 and 4 kPa, in order to single out the model best reproducing the absorption profile and, hence, the physical situation of self-colliding CO(2) molecules. Line intensity factors and self-broadening coefficients were determined. The 1-sigma overall accuracy of our determinations is at a level of 0.1%, which is, to our knowledge, the highest ever reached.
- Published
- 2009
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19. Primary gas thermometry by means of laser-absorption spectroscopy: determination of the Boltzmann constant.
- Author
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Casa G, Castrillo A, Galzerano G, Wehr R, Merlone A, Di Serafino D, Laporta P, and Gianfrani L
- Abstract
We report on a new optical implementation of primary gas thermometry based on laser-absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) nu1+2nu2(0)+nu3 transition in CO2 gas at thermodynamic equilibrium. Doppler width measurements as a function of gas temperature, ranging between the triple point of water and the gallium melting point, allowed for a spectroscopic determination of the Boltzmann constant with a relative accuracy of approximately 1.6 x 10(-4).
- Published
- 2008
- Full Text
- View/download PDF
20. Highly accurate determinations of CO(2) line strengths using intensity-stabilized diode laser absorption spectrometry.
- Author
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Casa G, Parretta DA, Castrillo A, Wehr R, and Gianfrani L
- Abstract
An intensity-stabilized laser absorption spectrometer, which incorporates a mirror-extended cavity diode laser, a temperature-stabilized gas cell, and a Michelson interferometer, was developed and applied to a highly accurate investigation of line intensity factors within the nu(1)+2nu(2) (0)+nu(3) combination band of carbon dioxide, around 2 microm wavelength, at a temperature of 296.0 K. This relatively complex apparatus enables one to observe the absorption line shape with high precision and accuracy in such a way that it is possible to retrieve the integrated absorbance with a relative uncertainty better than 0.1%. The absorption spectra were interpolated with the uncorrelated strong-collision model of Rautian and Sobel'man in order to take into account Dicke narrowing effects, thus obtaining an agreement at a level of a few parts per 10(-5). We report line strength values for the R(2)-R(18) transitions with an unprecedented level of accuracy, in the range between 0.1% and 0.15%. Finally, we discuss the possibility of providing a first experimental test of the theoretical model for molecular line strengths based on the Herman-Wallis expansion.
- Published
- 2007
- Full Text
- View/download PDF
21. Ablation of the cholesterol transporter adenosine triphosphate-binding cassette transporter G1 reduces adipose cell size and protects against diet-induced obesity.
- Author
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Buchmann J, Meyer C, Neschen S, Augustin R, Schmolz K, Kluge R, Al-Hasani H, Jürgens H, Eulenberg K, Wehr R, Dohrmann C, Joost HG, and Schürmann A
- Subjects
- ATP Binding Cassette Transporter, Subfamily G, Member 1, ATP-Binding Cassette Transporters physiology, Adipose Tissue metabolism, Animals, Body Weight, Drosophila melanogaster, Female, Lipoproteins physiology, Male, Mice, Mice, Inbred C57BL, Mice, Inbred NZB, Mice, Knockout, Mice, Obese, Obesity etiology, Obesity genetics, ATP-Binding Cassette Transporters genetics, Adipocytes cytology, Cell Size, Diet adverse effects, Lipoproteins genetics, Obesity prevention & control
- Abstract
The ATP-binding cassette transporter G1 (ABCG1) catalyzes export of cellular cholesterol from macrophages and hepatocytes. Here we identify an additional function of ABCG1 in the regulation of adiposity in screens of the Drosophila melanogaster and the New Zealand obese (NZO) mouse genomes. Insertion of modified transposable elements of the P-family upstream of CG17646, the Drosophila ortholog of Abcg1, generated lines of flies with increased triglyceride stores. In NZO mice, an Abcg1 variant was identified in a suggestive adiposity quantitative trait locus and was associated with higher expression of the gene in white adipose tissue. Targeted disruption of Abcg1 in mice resulted in reduced body weight gain (8.42+/-0.6 g in Abcg1-/- vs. 13.07+/-1.1 g in Abcg1+/+ mice) and adipose tissue mass gain (3.78+/-1.3 g in Abcg1-/- vs. 9.39+/-1.6 g in Abcg1+/+ mice) detected over a period of 12 wk. The reduction of adipose tissue mass in Abcg1-/- mice was associated with markedly decreased size of the adipocytes. In contrast to their wild-type littermates, male Abcg1-/- mice exhibited no high-fat diet-induced impairment of glucose tolerance and fatty liver. Furthermore, Abcg1-/- mice possess decreased food intake and elevated total energy expenditure (Abcg1-/- mice, 748.1+/-5.4 kJ/kg metabolic body mass; Abcg1+/+ mice, 684.3+/-5.0 kJ/kg metabolic body mass; P=0.011), body temperature (Abcg1-/- mice, 37.82+/-0.29 C; Abcg1+/+ mice, 36.83+/-0.24 C; P<0.05), and locomotor activity (Abcg1-/- mice, 3655+/-189 counts/12 h during dark phase; Abcg1+/+ mice, 2445+/-235 counts/12 h during dark phase; P<0.01). Our data indicate a previously unrecognized role of ABCG1 in the regulation of energy balance and triglyceride storage.
- Published
- 2007
- Full Text
- View/download PDF
22. Design of a difference-frequency infrared laser spectrometer for absorption line-shape studies.
- Author
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Wehr R, Drummond JR, and May AD
- Abstract
An infrared laser spectrometer based on difference-frequency generation in LiIO(3) is described. The spectrometer has a frequency uncertainty of less than 1 MHz and a signal-to-noise ratio between 3000:1 and 10,000:1. These properties allow the spectrometer to be used for studies of the non-Lorentzian and non-Voigt character of absorption line shapes in atmospheric trace gases.
- Published
- 2007
- Full Text
- View/download PDF
23. Expression of uncoupling protein 1 in skeletal muscle decreases muscle energy efficiency and affects thermoregulation and substrate oxidation.
- Author
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Klaus S, Rudolph B, Dohrmann C, and Wehr R
- Subjects
- Animals, Body Composition, Carrier Proteins genetics, Eating genetics, Eating physiology, Energy Metabolism genetics, Female, Gene Expression Regulation, Homeostasis physiology, Ion Channels, Male, Membrane Proteins genetics, Mice, Mice, Inbred C57BL, Mice, Transgenic, Mitochondrial Proteins, Time Factors, Transgenes, Uncoupling Protein 1, Body Temperature Regulation, Carrier Proteins metabolism, Energy Metabolism physiology, Membrane Proteins metabolism, Muscle, Skeletal metabolism, Oxidation-Reduction
- Abstract
Skeletal muscle uncoupling by ectopic expression of mitochondrial uncoupling protein 1 (UCP1) has been shown to result in a lean phenotype in mice characterized by increased energy expenditure (EE), resistance to diet-induced obesity, and improved glucose tolerance. Here, we investigated in detail the effect of ectopic UCP1 expression in skeletal muscle on thermoregulation and energy homeostasis in HSA-mUCP1 transgenic mice. Thermoneutrality was determined to be approximately 30 degrees C for both wild-type (WT) and transgenic mice. EE, body temperature (Tb), activity, and respiratory quotient (RQ) were then measured over 24 h at ambient temperatures (Ta) of 30, 22, and 5 degrees C. HSA-mUCP1 transgenic mice showed increased activity-related EE and heat loss but similar basal metabolic rate compared with WT. Tb at resting periods was progressively decreased with declining Ta in HSA-mUCP1 transgenic mice but not in WT. Compared with WT littermates, the transgenic HSA-mUCP1 mice displayed increased RQ levels during night time, indicative of increased overall glucose oxidation, and failed to decrease their RQ levels with declining Ta. Thus increased EE caused by skeletal muscle uncoupling is clearly due to a decreased muscle energy efficiency during activity combined with increased glucose oxidation and a compromised thermoregulation associated with increased overall heat loss. At Tas below thermoneutrality, this puts increasing energy demands on the animals, whereas at thermoneutrality most differences in energy metabolism are not apparent any more.
- Published
- 2005
- Full Text
- View/download PDF
24. High-resolution tunable mid-infrared spectrometer based on difference-frequency generation in AgGaS2.
- Author
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Vitcu A, Ciurylo R, Wehr R, Drummond JR, and May AD
- Abstract
We have built a high-resolution and high-signal-to-noise ratio spectrometer for line shape studies of greenhouse gases in the mid infrared. The infrared radiation is generated in a AgGaS2 nonlinear crystal by the well-known difference-frequency method. The choice of crystal is explained, and a brief literature review is presented. With two tunable dye lasers and a type I, 90 degrees phase-matching geometry, the infrared is continuously tunable from 7 to 9 microm when Rhodamine 6G and Sulforhodamine 640 dyes are used. The total infrared power exceeds 30 nW and is limited by both the damage threshold and thermal loading of the crystal. Phase-sensitive detection allows us to reach signal-to-noise ratios in excess of 3500:1 while maintaining an instrumental linewidth of 1.5 MHz. However, we show that the spectrometer may be used to measure the positions of spectral lines within +/-400 kHz.
- Published
- 2004
- Full Text
- View/download PDF
25. Dynamic spectroscopic measurements of the temperature and pressure cycles in a MOPITT pressure modulator cell.
- Author
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Wehr R, McKernan E, Vitcu A, Ciurylo R, and Drummond JR
- Abstract
The temperature and pressure cycles inside a pressure modulator cell (PMC) of the type used for gas-correlation radiometry aboard the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument have been determined from dynamic measurements of the spectral line shapes of the R(0) and R(18) transitions in the fundamental vibrational-rotational band of carbon monoxide. The line strengths and linewidths were used to calculate the temperature and pressure, respectively, with a temporal resolution of approximately 200 micros, or 1/100 of a PMC cycle. The results are compared with a thermodynamic box model.
- Published
- 2003
- Full Text
- View/download PDF
26. Pancreas development and diabetes.
- Author
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St-Onge L, Wehr R, and Gruss P
- Subjects
- Animals, Embryonic and Fetal Development physiology, Homeobox Protein Nkx-2.2, Homeodomain Proteins, Humans, Mesoderm, Notochord, Nuclear Proteins, Diabetes Mellitus, Type 2 genetics, Embryonic and Fetal Development genetics, Pancreas embryology, Transcription Factors physiology
- Abstract
The past few years have seen an increase in interest about the molecular and genetic events regulating pancreas development. Transcription factors such as Pdx1, p48 and Nkx2.2 have been shown to be essential for the proper differentiation of exocrine and endocrine tissue; however, pancreas development also involves intricate interactions between the pancreatic epithelium and its surrounding mesenchyme. Signalling factors emanating from the notochord have been shown to repress Sonic hedgehog expression in the endoderm whereas signals originating from the pancreatic mesenchyme determine the proportion of exocrine to endocrine tissue. Understanding the molecular and genetic events underlying pancreas development also opens the door for devising new therapeutic strategies against pancreatic diseases such as diabetes and cancer.
- Published
- 1999
- Full Text
- View/download PDF
27. The fork head transcription factor Fkh5/Mf3 is a developmental marker gene for superior colliculus layers and derivatives of the hindbrain somatic afferent zone.
- Author
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Alvarez-Bolado G, Cecconi F, Wehr R, and Gruss P
- Subjects
- Afferent Pathways embryology, Afferent Pathways growth & development, Aging physiology, Animals, Embryonic and Fetal Development physiology, Forkhead Transcription Factors, Genetic Markers, Inferior Colliculi embryology, Inferior Colliculi growth & development, Mice embryology, Mice growth & development, Mice, Inbred Strains, Telencephalon embryology, Telencephalon growth & development, Terminology as Topic, DNA-Binding Proteins genetics, Gene Expression physiology, Rhombencephalon embryology, Rhombencephalon growth & development, Superior Colliculi embryology, Superior Colliculi growth & development, Transcription Factors genetics
- Abstract
Fork head-5 (Fkh5; also known as Mf3 and TWH) is a transcription factor of the winged helix family. As part of an extended project to understand the function of this protein in the developing mouse brain, in the present work we have used Fkh5/Mf3 expression as a marker to study the development of the midbrain and hindbrain. In the midbrain, Fkh5/Mf3 is expressed in the superior colliculus, in the ventricular layer of the inferior colliculus and in the isthmus. In the superior colliculus, Fkh5/Mf3 is expressed by cells of layers 4a and 4c since early in development. In the hindbrain, Fkh5/Mf3 is a longitudinal marker (as opposed to a transverse or rhombomeric one), since it labels nuclei belonging to the somatic afferent zone (ventral cochlear nucleus, cuneate and external cuneate nuclei, principal and spinal nuclei of the trigeminal). In addition, Fkh5/Mf3 is expressed by the developing endopiriform nucleus and by the olivary pretectal nucleus. The results suggest that Fkh5/Mf3 has an early role in the lamination of the tectum and in the longitudinal differentiation of the hindbrain., (Copyright 1998 Elsevier Science B.V.)
- Published
- 1999
- Full Text
- View/download PDF
28. Vax1 is a novel homeobox-containing gene expressed in the developing anterior ventral forebrain.
- Author
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Hallonet M, Hollemann T, Wehr R, Jenkins NA, Copeland NG, Pieler T, and Gruss P
- Subjects
- Amino Acid Sequence, Animals, Brain embryology, Cell Differentiation genetics, Chromosome Mapping, Cloning, Molecular, DNA-Binding Proteins metabolism, Eye Proteins, Homeodomain Proteins metabolism, In Situ Hybridization, Mice, Molecular Sequence Data, PAX6 Transcription Factor, Paired Box Transcription Factors, RNA, Messenger metabolism, Repressor Proteins, Sequence Analysis, DNA, Sequence Homology, Amino Acid, Transcription Factors metabolism, Xenopus, Brain growth & development, Gene Expression Regulation, Developmental genetics, Genes, Homeobox genetics, Homeodomain Proteins chemistry, Neuropeptides chemistry, Xenopus Proteins
- Abstract
The vertebrate forebrain is formed at the rostral end of the neural plate under the regulation of local and specific signals emanating from both the endomesoderm and neuroectoderm. The development of the rostral and ventral forebrain in particular was difficult to study, mainly because no specific markers are available to date. Here, we report the identification of Vax1, a novel homeobox-containing gene identified in mouse, Xenopus and human. It is closely related to members of the Not and Emx gene families, all of which are required for the formation of structures where they are expressed. In mouse and Xenopus, Vax1 expression first occurs in the rostral neural plate, in the medial anterior neural ridge and adjacent ectoderm. Later, at midgestation in the mouse and tadpole stage in Xenopus, the expression remains confined in the derivatives of this territory which differentiate into rostromedial olfactory placode, optic nerve and disc, and anterior ventral forebrain. Together, these observations suggest that Vax1 could have an early evolutionary origin and could participate in the specification and formation of the rostral and ventral forebrain in vertebrates. Comparison of the limits of the expression territory of Vax1 with that of Dlx1, Pax6 and Emx1 indicates that the corticostriatal ridge is a complex structure with distinct identifiable genetic compartments. Besides, the study of Vax1 expression in Pax6-deficient homozygous brains indicates that its regulation is independent of Pax6, although the expression patterns of these two genes appear complementary in wild-type animals. Vax1 chromosomal location is mapped at the distal end of the mouse chromosome 19, linked with that of Emx2. These two genes may have arisen by tandem duplication. The Vax1 gene is thus an interesting new tool to study the rostral ventral forebrain patterning, morphogenesis and evolution as well as the terminal differentiation of the forebrain in mouse and Xenopus.
- Published
- 1998
- Full Text
- View/download PDF
29. Fkh5-deficient mice show dysgenesis in the caudal midbrain and hypothalamic mammillary body.
- Author
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Wehr R, Mansouri A, de Maeyer T, and Gruss P
- Subjects
- Animals, DNA-Binding Proteins genetics, Female, Forkhead Transcription Factors, Gene Expression Regulation, Developmental, Genotype, Growth Disorders genetics, Male, Mammillary Bodies embryology, Mammillary Bodies metabolism, Maternal Behavior, Mesencephalon embryology, Mesencephalon metabolism, Mice, Mice, Inbred C57BL, Mice, Knockout, Phenotype, Pregnancy, Transcription Factors genetics, DNA-Binding Proteins metabolism, Mammillary Bodies abnormalities, Mesencephalon abnormalities, Transcription Factors deficiency, Transcription Factors metabolism
- Abstract
The murine winged helix gene Fkh5 is specifically expressed in the developing central nervous system (CNS). Early embryonic Fkh5 expression is restricted to the mammiliary body region of the caudal hypothalamus, midbrain, hindbrain and spinal cord. Postnatally, signals persist in specific nuclei of the mammillary body and in the midbrain. We generated Fkh5 deficient mice by homologous recombination to assess its in vivo function. At birth, Fkh5-deficient mice are viable and indistinguishable from wild-type and Fkh5 heterozygous littermates. However, about one third die within the first two days and another fifth before weaning. Surviving Fkh5-deficient mice become growth retarded within the first week and remain smaller throughout their whole life span. Fkh5-deficient females on 129Sv x C57BL/6 genetic background are fertile, but do not nurture their pups. More detailed analysis of Fkh5-deficient brains reveals distinct alterations in the CNS. In the midbrain, mutant mice exhibit reduced inferior colliculi and an overgrown anterior cerebellum. Furthermore, the hypothalamic mammillary body of Fkh5-deficient brains lacks the medial mammillary nucleus. These results suggest that Fkh5 plays a major role during CNS development.
- Published
- 1997
- Full Text
- View/download PDF
30. Paired-related murine homeobox gene expressed in the developing sclerotome, kidney, and nervous system.
- Author
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Mansouri A, Yokota Y, Wehr R, Copeland NG, Jenkins NA, and Gruss P
- Subjects
- Amino Acid Sequence, Animals, Base Sequence, Cell Line, Chromosome Mapping, Cloning, Molecular, Kidney metabolism, Mice, Molecular Sequence Data, Nervous System metabolism, Somites metabolism, Tretinoin pharmacology, Genes, Homeobox, Homeodomain Proteins genetics, Kidney embryology, Nervous System embryology
- Abstract
We isolated a murine homeobox containing gene, Uncx4.1. The homeodomain sequence exhibits 88% identity to the unc-4 protein at the amino acid level. In situ hybridization analysis revealed that Uncx4.1 is expressed in the paraxial mesoderm, in the developing kidney, and central nervous system. The most intriguing expression domain is the somite, where it is confined to the caudal part of the newly formed somite and subsequently restricted to the caudal domain of the developing sclerotome. In the central nervous system, Uncx4.1 is detected in the developing spinal cord, hindbrain, mesencephalon, and telencephalon. The temporal and spatial expression pattern suggests that Uncx4.1 may play an important role in kidney development and in the differentiation of the sclerotome and the nervous system.
- Published
- 1997
- Full Text
- View/download PDF
31. Pax and vertebrate development.
- Author
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Wehr R and Gruss P
- Subjects
- Animals, Aniridia embryology, Aniridia genetics, Central Nervous System embryology, Female, Gene Expression Regulation, Developmental, Humans, Mice, Mutation, Neoplasms etiology, Neoplasms genetics, Pregnancy, Waardenburg Syndrome embryology, Waardenburg Syndrome genetics, Embryonic and Fetal Development genetics, Transcription Factors genetics
- Abstract
Pax genes encode transcription factors sharing a highly conserved sequence, the paired box. Their temporally and spatially restricted expression patterns during development indicate that Pax genes are involved in important steps of nervous system formation. Mutations in Pax genes have been correlated with three mouse mutants (undulated, splotch, small eye) and two human diseases (Waardenburg syndrome, aniridia). Recent data demonstrated that deregulation of Pax genes contributes to tumor formation.
- Published
- 1996
32. Six3, a murine homologue of the sine oculis gene, demarcates the most anterior border of the developing neural plate and is expressed during eye development.
- Author
-
Oliver G, Mailhos A, Wehr R, Copeland NG, Jenkins NA, and Gruss P
- Subjects
- Amino Acid Sequence, Animals, Base Sequence, Chromosome Mapping, Drosophila genetics, Gene Expression, In Situ Hybridization, Mice, Mice, Inbred Strains, Mice, Mutant Strains, Molecular Sequence Data, Morphogenesis genetics, Sequence Homology, Amino Acid, Homeobox Protein SIX3, Central Nervous System embryology, Drosophila Proteins, Eye embryology, Eye Proteins genetics, Genes, Homeobox, Homeodomain Proteins genetics, Nerve Tissue Proteins genetics
- Abstract
The Drosophila sine oculis homeobox-containing gene is known to play an essential role in controlling the initial events of pattern formation in the eye disc and is also required for the development of other parts of the fly visual system including the optic lobes. In this paper, we report the isolation of a sequence-related gene referred to as Six3. Based on its amino acid sequence, this gene can be included in the new Six/sine oculis subclass of homeobox genes. Early on, Six3 expression is restricted to the anterior neural plate including areas that later will give rise to ectodermal and neural derivatives. Later, once the longitudinal axis of the brain bends, Six3 mRNA is also found in structures derived from the anterior neural plate: ectoderm of nasal cavity, olfactory placode and Rathke's pouch, and also the ventral forebrain including the region of the optic recess, hypothalamus and optic vesicles. Based on this expression pattern, we conclude that Six3 is one of the most anterior homeobox gene reported to date. The high sequence similarity of Six3 with the Drosophila sine oculis, and its expression during eye development, suggests that this gene is the likely murine homologue. This finding supports the idea that mammals and insects share control genes such as eyeless/Pax6 (Halder, G., Callaerts, P. and Gehring, W. J. (1995) Science 267, 1788-1792), and also possibly other members of the regulatory cascade required for eye morphogenesis. In Small eye (Pax6) mouse mutants Six3 expression is not affected. Finally, based on the chromosomal localization and the expression pattern of the mouse Six3 gene, the human Six3 cognate could be a good candidate to be at least one of the genes affected in patients with holoprosencephaly type 2 due to an interstitial deletion of 2p21-p22. This region shares a homology with the distal region of mouse chromosome 17 where Six3 has been mapped.
- Published
- 1995
- Full Text
- View/download PDF
33. Segment-specific expression of the neuronatin gene during early hindbrain development.
- Author
-
Wijnholds J, Chowdhury K, Wehr R, and Gruss P
- Subjects
- Alternative Splicing, Amino Acid Sequence, Animals, Base Sequence, Cell Differentiation, Cell Line, Transformed, DNA, Complementary, Gene Expression Regulation, Developmental, Mice, Molecular Sequence Data, Neoplastic Stem Cells, Neural Crest cytology, Peripheral Nervous System embryology, Peripheral Nervous System metabolism, Pituitary Gland embryology, Pituitary Gland metabolism, RNA, Messenger genetics, Rhombencephalon metabolism, Sequence Homology, Amino Acid, Spinal Cord embryology, Spinal Cord metabolism, Membrane Proteins genetics, Nerve Tissue Proteins genetics, Rhombencephalon embryology
- Abstract
The developing hindbrain is segmented in a series of repetitive bulges called neuromeres or rhombomeres. In the mouse, first molecular evidence for segmentation of the hindbrain came from rhombomeres 3- and 5-specific expression of the Krox-20 gene. The hindbrain segments are linked with the expression of different Hox genes which have a role in patterning the hindbrain and branchial region of the vertebrate head. Here we identified by subtractive hybridization a gene, mouse neuronatin, that is downregulated in P19 embryo carcinoma cells that have undergone a partial differentiation process. Neuronatin encodes putative transmembrane proteins of 54, 55, and 81 amino acids that might serve as protein ligands, cofactors, or small cell adhesion molecules. The neuronatin gene is transiently expressed in rhombomeres 3 and 5 during early hindbrain development and in the floor of the foregut pocket. In addition, expression is observed in the early Rathke's pouch, in the derived adenohypophysis, and in the developing inner ear. During later embryogenesis the neuronatin gene is strongly expressed in the major part of the central and peripheral nervous system. These results suggest that neuronatin participates in the maintenance of segment identity in the hindbrain and pituitary development and maturation or maintenance of the overall structure of the nervous system.
- Published
- 1995
- Full Text
- View/download PDF
34. Homeobox genes and connective tissue patterning.
- Author
-
Oliver G, Wehr R, Jenkins NA, Copeland NG, Cheyette BN, Hartenstein V, Zipursky SL, and Gruss P
- Subjects
- Amino Acid Sequence, Animals, Base Sequence, Blotting, Northern, Chromosome Mapping, Drosophila genetics, Gene Expression, In Situ Hybridization, Ligaments embryology, Mice, Molecular Sequence Data, Morphogenesis genetics, Muscle, Skeletal embryology, Muscle, Smooth embryology, Tendons embryology, Connective Tissue embryology, Extremities embryology, Genes, Homeobox
- Abstract
In vertebrates, limb tendons are derived from cells that migrate from the lateral plate mesoderm during early development. While some of the developmental steps leading to the formation of these tissues are known, little is known about the molecular mechanisms controlling them. We have identified two murine homeobox-containing genes, Six 1 and Six 2, which are expressed in a complementary fashion during the development of limb tendons. Transcripts for both genes are found in different sets of phalangeal tendons. Six 1 and Six 2 also are expressed in skeletal and smooth muscle, respectively. These genes may participate in the patterning of the distal tendons of the limb phalanges by setting positional values along the limb axes.
- Published
- 1995
- Full Text
- View/download PDF
35. A controlled comparative efficacy study of 5% ammonium lactate lotion versus an emollient control lotion in the treatment of moderate xerosis.
- Author
-
Wehr RF, Kantor I, Jones EL, McPhee ME, and Krochmal L
- Subjects
- Double-Blind Method, Emollients administration & dosage, Female, Humans, Lactates administration & dosage, Lactic Acid, Leg, Lipids, Middle Aged, Ointment Bases administration & dosage, Skin drug effects, Emollients therapeutic use, Ichthyosis drug therapy, Lactates therapeutic use, Ointment Bases therapeutic use
- Published
- 1991
- Full Text
- View/download PDF
36. Evaluation of ammonium lactate in the treatment of seborrheic keratoses.
- Author
-
Klaus MV, Wehr RF, Rogers RS 3rd, Russell TJ, and Krochmal L
- Subjects
- Dermatitis, Seborrheic pathology, Double-Blind Method, Emollients therapeutic use, Humans, Keratosis pathology, Lactic Acid, Microscopy, Electron, Scanning, Skin Pigmentation, Dermatitis, Seborrheic drug therapy, Keratosis drug therapy, Lactates therapeutic use
- Abstract
A double-blind, paired comparison study was used to evaluate treatment effects of 12% ammonium lactate lotion (Lac-Hydrin) against its vehicle on seborrheic keratoses. Fifty-eight volunteer patients, 37 to 82 years of age, were studied for 16 weeks. The patients had a minimum of two seborrheic keratoses at least 10 cm apart. They applied the medication twice daily. The lesions were evaluated for height, surface characteristics, color, and length with the use of 7X calibrated loupe, a template, skin replicas, and scanning electron microscopy. Lac-Hydrin 12% lotion significantly reduced the height (elevation) of seborrheic keratoses, and two seborrheic keratoses cleared completely; however, there was no statistically significant difference in the length, color, and surface characteristics between the study group and the control group. Skin replicas and scanning electron microscopy can be used to evaluate lesion surface characteristics, dimensions, and therapeutic effects.
- Published
- 1990
- Full Text
- View/download PDF
37. Corticosteroid-induced cutaneous atrophy and telangiectasia. Experimental production associated with weight loss in rats.
- Author
-
Smith JG Jr, Wehr RF, and Chalker DK
- Subjects
- Administration, Topical, Animals, Atrophy, Betamethasone adverse effects, Dexamethasone adverse effects, Flumethasone adverse effects, Fluocinolone Acetonide adverse effects, Fluocinonide adverse effects, Flurandrenolone adverse effects, Hydrocortisone adverse effects, Male, Rats, Triamcinolone adverse effects, Adrenal Cortex Hormones adverse effects, Body Weight drug effects, Disease Models, Animal, Skin Diseases chemically induced, Telangiectasis chemically induced
- Abstract
A bioassay for the evaluation of certain adverse effects of various corticosteroids was performed. Twenty-eight daily topical applications of corticosteroids to young rats produced reduction in body-weight gain, atrophy of the skin as determined by double skin-fold thickness micrometer measurement, and mild to severe telangiectasia. This animal model demonstrates corticosteroid-induced skin atrophy and telangiectasia and the correlation of the degree of atrophy and telangiectasia to body-weight change. Nine corticosteroids were evaluated by this method and are listed in terms of increasing severity of side-effects as follows: 1.0% hydrocortisone cream, 0.1% betamethasone valerate cream, 0.025% betamethasone benzoate cream, 0.05% flurandrenolide cream, 0.05% fluocinonide cream, 0.1% dexamethasone cream, and 0.03% flumethasone pivalate cream. Triamcinolone acetonide cream, 0.5%, and 0.2% fluocinolone acetonide cream resulted in death of the animals prior to completion of 28 days of topical application.
- Published
- 1976
38. A microcomputer database for mental health program evaluation.
- Author
-
Wehr RJ
- Subjects
- Evaluation Studies as Topic, Nova Scotia, Computers, Hospital Information Systems standards, Mental Health Services organization & administration, Microcomputers, Psychiatric Department, Hospital organization & administration
- Abstract
This article describes the development of a microcomputer database within the Mental Health Division of a regional hospital. The multiple uses of this database are illustrated and include management information, program evaluation, assistance with case management and quality assurance, and applied clinical research. Guidance is given on choosing appropriate software and hardware and on negotiating with information providers and funding agencies.
- Published
- 1987
39. Vitamin A prevention of triamcinolone acetonide effects on granuloma growth: lack of effect on prolyl hydroxylase.
- Author
-
Wehr RF, Smith JG Jr, Counts DF, and Cutroneo KR
- Subjects
- Animals, Collagen biosynthesis, DNA metabolism, Granuloma metabolism, Granuloma pathology, Hydroxyproline metabolism, Male, Proteins metabolism, Rats, Granuloma enzymology, Procollagen-Proline Dioxygenase metabolism, Triamcinolone Acetonide antagonists & inhibitors, Vitamin A pharmacology
- Published
- 1976
- Full Text
- View/download PDF
40. Considerations in selecting a moisturizer.
- Author
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Wehr RF and Krochmal L
- Subjects
- Collagen, Emollients, Humans, Pharmaceutical Vehicles, Preservatives, Pharmaceutical, Surface-Active Agents, Cosmetics, Dermatologic Agents, Skin Diseases drug therapy
- Abstract
The symptoms of xerosis (dry skin) can be ameliorated by increasing the hydration state of the stratum corneum through a humectant or occlusive effect, smoothing the rough surface with an emollient, replenishing natural moisturizing factors, and normalizing the stratum corneum. We present the primary and secondary functions of various "active" and vehicle ingredients and include precautions regarding certain classes of materials. Recommendations on selecting moisturizing systems are made based on ingredient functionality and the severity of the dry skin condition.
- Published
- 1987
41. Therapeutic activity of lactate 12% lotion in the treatment of ichthyosis. Active versus vehicle and active versus a petrolatum cream.
- Author
-
Buxman M, Hickman J, Ragsdale W, Stretcher G, Krochmal L, and Wehr RF
- Subjects
- Administration, Topical, Adolescent, Adult, Aged, Aged, 80 and over, Child, Child, Preschool, Clinical Trials as Topic, Humans, Ichthyosis genetics, Lactic Acid, Middle Aged, Pharmaceutical Vehicles, Ichthyosis drug therapy, Lactates therapeutic use, Petrolatum therapeutic use
- Abstract
Lactate 12% lotion was significantly more effective than both its vehicle and a petrolatum-based cream in the treatment of ichthyosis. The treatment regimen was twice-daily application for 4 weeks with evaluations weekly during the treatment period and for 2 weeks after treatment was stopped. Vulgaris, lamellar, sex-linked, Netherton's, and epidermolytic hyperkeratotic forms of ichthyosis were significantly improved by treatment with lactate 12% lotion. This new therapeutic modality expands the scope and extent of ichthyotic conditions that may now be successfully treated.
- Published
- 1986
- Full Text
- View/download PDF
42. Efficacy of Alpha Keri after showering for treatment of xerosis.
- Author
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Wehr R, Krochmal L, Whitmore C, and Yarbrough C
- Subjects
- Adult, Baths, Clinical Trials as Topic, Female, Humans, Middle Aged, Oils therapeutic use, Skin Diseases drug therapy, Surface-Active Agents therapeutic use
- Abstract
The use of Alpha Keri bath oil in a postshower therapeutic regimen was effective in reducing the severity of moderate to severe xerosis.
- Published
- 1986
43. Comparative efficacy of 12% ammonium lactate lotion and 5% lactic acid lotion in the treatment of moderate to severe xerosis.
- Author
-
Rogers RS 3rd, Callen J, Wehr R, and Krochmal L
- Subjects
- Adult, Aged, Double-Blind Method, Drug Evaluation, Female, Humans, Lactic Acid, Male, Middle Aged, Severity of Illness Index, Ichthyosis drug therapy, Lactates therapeutic use
- Abstract
This double-blind study was designed to evaluate treatment results and time effects of 12% ammonium lactate and 5% lactic acid lotion for moderate to severe xerosis. Results showed 12% ammonium lactate lotion was significantly more effective than 5% lactic acid lotion in reducing the severity of xerosis in both the 3-week, twice-a-day treatment period and the following 3-week, no-treatment (regression) period.
- Published
- 1989
- Full Text
- View/download PDF
44. A controlled two-center study of lactate 12 percent lotion and a petrolatum-based creme in patients with xerosis.
- Author
-
Wehr R, Krochmal L, Bagatell F, and Ragsdale W
- Subjects
- Clinical Trials as Topic, Double-Blind Method, Humans, Lactates administration & dosage, Ointments, Petrolatum administration & dosage, Skin Diseases drug therapy
- Abstract
Lactic acid, one of the most widely distributed acids in nature, is present in biological fluids and tissues of humans as an intermediary in carbohydrate metabolism. Alpha-hydroxy acids, including lactic acid, and their salts have been recommended for the treatment of keratinization disorders. This controlled double-blind study compares the efficacy of lactate 12 percent lotion and a petrolatum-based therapeutic creme (creme B) in patients with moderate to severe xerosis. Lactate 12 percent lotion was significantly more effective than a petrolatum-based creme in reducing the severity of xerosis during treatment and post-treatment phases.
- Published
- 1986
45. Urinary hydroxyproline: source of increase after thermal burns.
- Author
-
Smith JG Jr, Wehr RF, Badger NL, and Pirkle DE
- Subjects
- Animals, Female, Rats, Time Factors, Burns urine, Collagen metabolism, Hydroxyproline urine
- Published
- 1974
- Full Text
- View/download PDF
46. The effectiveness of topical and oral tetracycline for acne.
- Author
-
Smith JG Jr, Chalker DK, and Wehr RF
- Subjects
- Administration, Oral, Administration, Topical, Adolescent, Adult, Clinical Trials as Topic, Female, Humans, Male, Tetracycline administration & dosage, Tetracycline adverse effects, Acne Vulgaris drug therapy, Tetracycline therapeutic use
- Abstract
A group of 135 college students with acne was evaluated in a 12-week, double-blind study comparing placebo, oral tetracycline 0.5 gm daily, and a new topical tetracycline preparation. The topical tetracycline preparation containing n-decyl methyl sulfoxide to enhance penetration, produced statistically significant improvement of acne as compared to placebo after 7, 10, and 12 weeks of treatment. Oral tetracycline, 0.5 gm daily, was statistically significantly more effective for acne than placebo after 4, 7, 10, and 12 weeks of therapy. The placebo group also had marked improvement which may have been related to sun exposure. Emotional stress produced by final examinations had no apparent effect on the patients given placebo, oral, or topical tetracycline. Side effects of the topical tetracycline included a slight yellowish discoloration of the skin in 25% of the subjects and transient stinging or tingling sensation after application in 36%.
- Published
- 1976
- Full Text
- View/download PDF
47. Effective treatment of Netherton's syndrome with 12% lactate lotion.
- Author
-
Wehr RF, Hickman J, and Krochmal L
- Subjects
- Adolescent, Erythema drug therapy, Female, Humans, Keratosis drug therapy, Male, Syndrome, Ichthyosis drug therapy, Lactates therapeutic use
- Published
- 1988
- Full Text
- View/download PDF
48. Effects of calisthenics on selected components of physical fitness.
- Author
-
Campney HK and Wehr RW
- Subjects
- Adult, Female, Humans, Male, Middle Aged, Gymnastics, Physical Fitness
- Published
- 1965
49. Amino acids in blood plasma of young and aged adults.
- Author
-
Wehr RF and Lewis GT
- Subjects
- Adult, Aged, Autoanalysis, Blood, Brain Damage, Chronic, Chemistry, Clinical, Humans, In Vitro Techniques, Amino Acids
- Published
- 1966
- Full Text
- View/download PDF
50. A congenital hair defect: trichoschisis with alternating birefringence and low sulfur content.
- Author
-
Brown AC, Belser RB, Crounse RG, and Wehr RF
- Subjects
- Amino Acids analysis, Amino Acids urine, Birefringence, Child, Preschool, Female, Humans, Microscopy, Polarization, Skin Diseases metabolism, Skin Diseases pathology, Sulfur analysis, Sulfur metabolism, Hair metabolism, Hair pathology, Skin Diseases congenital
- Published
- 1970
- Full Text
- View/download PDF
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