Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 77
Filter
1.
Sci Total Environ ; 912: 168901, 2024 Feb 20.
Article in English | MEDLINE | ID: mdl-38042198

ABSTRACT

Use of nutrients recycled from societal waste streams in agriculture is part of the circular economy, and in line with organic farming principles. Nevertheless, diverse contaminants in waste streams create doubts among organic farmers about potential risks for soil health. Here, we gather the current knowledge on contaminant levels in waste streams and recycled nutrient sources, and discuss associated risks. For potentially toxic elements (PTEs), the input of zinc (Zn) and copper (Cu) from mineral feed supplements remains of concern, while concentrations of PTEs in many waste streams have decreased substantially in Europe. The same applies to organic contaminants, although new chemical groups such as flame retardants are of emerging concern and globally contamination levels differ strongly. Compared to inorganic fertilizers, application of organic fertilizers derived from human or animal feces is associated with an increased risk for environmental dissemination of antibiotic resistance. The risk depends on the quality of the organic fertilizers, which varies between geographical regions, but farmland application of sewage sludge appears to be a safe practice as shown by some studies (e.g. from Sweden). Microplastic concentrations in agricultural soils show a wide spread and our understanding of its toxicity is limited, hampering a sound risk assessment. Methods for assessing public health risks for organic contaminants must include emerging contaminants and potential interactions of multiple compounds. Evidence from long-term field experiments suggests that soils may be more resilient and capable to degrade or stabilize pollutants than often assumed. In view of the need to source nutrients for expanding areas under organic farming, we discuss inputs originating from conventional farms vs. non-agricultural (i.e. societal) inputs. Closing nutrient cycles between agriculture and society is feasible in many cases, without being compromised by contaminants, and should be enhanced, aided by improved source control, waste treatment and sound risk assessments.


Subject(s)
Organic Agriculture , Soil Pollutants , Animals , Humans , Fertilizers/analysis , Plastics , Agriculture/methods , Soil/chemistry , Risk Assessment , Nutrients , Soil Pollutants/analysis , Sewage/chemistry
2.
Chemistry ; 28(63): e202201738, 2022 Nov 11.
Article in English | MEDLINE | ID: mdl-35951451

ABSTRACT

The preparation of novel technetium oxides, their characterization and the general investigation of technetium chemistry are of significant importance, since fundamental research has so far mainly focused on the group homologues. Whereas the structure chemistry of technetium in strongly oxidizing media is dominated by the Tc O 4 - ${{\left[{\rm { Tc}}{{\rm { O}}}_{{\rm { 4}}}\right]}^{-}}$ anion, our recent investigation yielded the new Tc O 3 N 2 - ${{\left[{\rm { Tc}}{{\rm { O}}}_{{\rm { 3}}}{\rm { N}}\right]}^{{\rm { 2}}-}}$ anion. Brown single crystals of Ba[TcO3 N] were obtained under hydrothermal conditions starting from Ba(OH)2 ⋅ 8H2 O and NH4 [TcO4 ] at 200 °C. Ba [ Tc O 3 N ] ${{\rm { Ba[Tc}}{{\rm { O}}}_{{\rm { 3}}}{\rm { N]}}}$ crystallizes in the monoclinic crystal system with the space group P21 /n (a=7.2159(4) Å, b=7.8536(5) Å, c=7.4931(4) Šand ß=104.279(2)°). The crystal structure of Ba [ Tc O 3 N ] ${{\rm { Ba[Tc}}{{\rm { O}}}_{{\rm { 3}}}{\rm { N]}}}$ consists of isolated Tc O 3 N 2 - ${{\left[{\rm { Tc}}{{\rm { O}}}_{{\rm { 3}}}{\rm { N}}\right]}^{{\rm { 2}}-}}$ tetrahedra, which are surrounded by Ba2+ cations. XANES measurements complement the oxidation state +VII for technetium and Raman spectroscopic experiments on Ba[TcO3 N] single crystals exhibit characteristic Tc-O and Tc-N vibrational modes.

3.
Phys Rev Lett ; 122(22): 227401, 2019 Jun 07.
Article in English | MEDLINE | ID: mdl-31283293

ABSTRACT

Entangled photon sources are crucial for quantum optics, quantum sensing, and quantum communication. Semiconductor quantum dots generate on-demand entangled photon pairs via the biexciton-exciton cascade. However, the pair of photons are emitted isotropically in all directions, thus limiting the collection efficiency to a fraction of a percent. Moreover, strain and structural asymmetry in quantum dots lift the degeneracy of the intermediate exciton states in the cascade, thus degrading the measured entanglement fidelity. Here, we propose an approach for generating a pair of entangled photons from a semiconductor quantum dot by application of a quadrupole electrostatic potential. We show that the quadrupole electric field corrects for the spatial asymmetry of the excitonic wave function for any quantum dot dipole orientation and fully erases the fine-structure splitting without compromising the spatial overlap between electrons and holes. Our approach is compatible with nanophotonic structures such as microcavities and nanowires, thus paving the way towards a deterministic source of entangled photons with high fidelity and collection efficiency.

4.
Opt Express ; 26(19): 24487-24496, 2018 Sep 17.
Article in English | MEDLINE | ID: mdl-30469565

ABSTRACT

We analyze the degree of entanglement measurable from a quantum dot via the biexciton-exciton cascade as a function of the exciton fine-structure splitting and the detection time resolution. We show that the time-energy uncertainty relation provides means to measure a high entanglement even in presence of a finite fine-structure splitting when a detection system with high temporal resolution is employed. Still, in many applications it would be beneficial if the fine-structure splitting could be compensated to zero. To solve this problem, we propose an all-optical approach with rotating waveplates to erase this fine-structure splitting completely which should allow obtaining a high degree of entanglement with near-unity efficiency. Our optical approach is possible with current technology and is also compatible with any quantum dot showing fine-structure splitting. This bears the advantage that for example the fine-structure splitting of quantum dots in nanowires and micropillars can be directly compensated without the need for further sample processing.

5.
Eur J Pain ; 22(8): 1517-1527, 2018 Sep.
Article in English | MEDLINE | ID: mdl-29756270

ABSTRACT

BACKGROUND: Human experimental pain models in healthy subjects offer unique possibilities to study mechanisms of pain within a defined setting of expected pain symptoms, signs and mechanisms. Previous trials in healthy subjects demonstrated that topical application of 40% menthol is suitable to induce cold hyperalgesia. The objective of this study was to evaluate the impact of suggestion on this experimental human pain model. METHODS: The study was performed within a single-centre, randomized, placebo-controlled, double-blind, two-period crossover trial in a cohort of 16 healthy subjects. Subjects were tested twice after topical menthol application (40% dissolved in ethanol) and twice after ethanol (as placebo) application. In the style of a balanced placebo trial design, the subjects received during half of the testing the correct information about the applied substance (topical menthol or ethanol) and during half of the testing the incorrect information, leading to four tested conditions (treatment conditions: menthol-told-menthol and menthol-told-ethanol; placebo conditions: ethanol-told-menthol and ethanol-told-ethanol). RESULTS: Cold but not mechanical hyperalgesia was reliably induced by the model. The cold pain threshold decreased in both treatment conditions regardless whether true or false information was given. Minor suggestion effects were found in subjects with prior ethanol application. CONCLUSIONS: The menthol model is a reliable, nonsuggestible model to induce cold hyperalgesia. Mechanical hyperalgesia is not as reliable to induce. SIGNIFICANCE: Cold hyperalgesia may be investigated under unbiased and suggestion-free conditions using the menthol model of pain.

6.
Leukemia ; 31(3): 712-719, 2017 03.
Article in English | MEDLINE | ID: mdl-27554164

ABSTRACT

Acute myelogenous leukemia (AML) is a high-risk hematopoietic malignancy caused by a variety of mutations, including genes encoding the cohesin complex. Recent studies have demonstrated that reduction in cohesin complex levels leads to enhanced self-renewal in hematopoietic stem and progenitors (HSPCs). We sought to delineate the molecular mechanisms by which cohesin mutations promote enhanced HSPC self-renewal as this represents a critical initial step during leukemic transformation. We verified that RNAi against the cohesin subunit Rad21 causes enhanced self-renewal of HSPCs in vitro through derepression of polycomb repressive complex 2 (PRC2) target genes, including Hoxa7 and Hoxa9. Importantly, knockdown of either Hoxa7 or Hoxa9 suppressed self-renewal, implying that both are critical downstream effectors of reduced cohesin levels. We further demonstrate that the cohesin and PRC2 complexes interact and are bound in close proximity to Hoxa7 and Hoxa9. Rad21 depletion resulted in decreased levels of H3K27me3 at the Hoxa7 and Hoxa9 promoters, consistent with Rad21 being critical to proper gene silencing by recruiting the PRC2 complex. Our data demonstrates that the cohesin complex regulates PRC2 targeting to silence Hoxa7 and Hoxa9 and negatively regulate self-renewal. Our studies identify a novel epigenetic mechanism underlying leukemogenesis in AML patients with cohesin mutations.


Subject(s)
Cell Self Renewal/genetics , Epigenetic Repression , Gene Expression Regulation , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/metabolism , Homeodomain Proteins/genetics , Neoplasm Proteins/genetics , Nuclear Proteins/metabolism , Phosphoproteins/metabolism , Aneuploidy , Animals , Cell Cycle Proteins/chemistry , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Proliferation , Chromosomal Proteins, Non-Histone/chemistry , Chromosomal Proteins, Non-Histone/genetics , Chromosomal Proteins, Non-Histone/metabolism , Cluster Analysis , DNA-Binding Proteins , Gene Deletion , Gene Expression Profiling , Histones/metabolism , Homeodomain Proteins/metabolism , Mice , Models, Biological , Multigene Family , Multiprotein Complexes/metabolism , Myeloid Cells/cytology , Myeloid Cells/metabolism , Protein Binding , Protein Interaction Domains and Motifs/genetics , Cohesins
7.
Eur J Pain ; 21(2): 322-333, 2017 02.
Article in English | MEDLINE | ID: mdl-27510567

ABSTRACT

BACKGROUND: Many chronic low back pain (cLBP) patients do not satisfactorily respond to treatment. The knowledge of responders and non-responders before initiating treatment would improve decision making and reduce health care costs. The aims of this exploratory prediction study in cLBP patients treated with tapentadol were to identify predictors of treatment outcome based on baseline characteristics, to evaluate quality-of-life and functionality as alternative outcome parameters and to develop nomograms to calculate the individual probability of response. METHODS: In a retrospective analysis of an open-label phase 3b trial, 46 baseline characteristics were included into statistical prediction modelling. One hundred and twenty-one patients were followed up during the titration and treatment period and 67 patients were analysed who discontinued the trial. RESULTS: Demographic data were not relevant for response prediction. Nine baseline co-variables were robust: painDETECT score, intensity of burning and painful attacks, SF36 Health Survey score (MCS, PCS), EuroQol-5, Hospital Anxiety/Depression Scale. Gender had a minor influence. Alternative outcomes (quality-of-life, functionality) were more important for response prediction than conventional pain intensity measures. Neuropathic symptoms (high painDETECT score) had a positive predictive validity. Painful attacks and classical yellow flags (depression, anxiety) negatively influenced the treatment response. High depression scores, female gender and low burning predicted discontinuation during titration. CONCLUSION: In this exploratory study, predictive baseline characteristics have been identified that can be used to calculate the individual probability of tapentadol response in cLBP. The small sample size in relation to the number of initial variables is a limitation of this approach. SIGNIFICANCE: Predictors for treatment response of tapentadol were identified in patients with chronic low back pain based on clinical pre-treatment characteristics that can guide personalized treatment. Quality-of-life and functionality were the most relevant outcomes for response prediction.


Subject(s)
Chronic Pain/drug therapy , Low Back Pain/drug therapy , Phenols/therapeutic use , Adult , Aged , Chronic Pain/diagnosis , Delayed-Action Preparations , Female , Humans , Low Back Pain/diagnosis , Male , Middle Aged , Retrospective Studies , Tapentadol , Treatment Outcome
8.
Eur J Pain ; 20(10): 1730-1740, 2016 11.
Article in English | MEDLINE | ID: mdl-27263529

ABSTRACT

BACKGROUND: Cold-evoked potentials (CEPs) are known to assess the integrity of A-delta fibres and the spinothalamic tract. Nevertheless, the clinical value was not investigated previously. The aim of this study was to measure CEPs in 16 healthy subjects from the face, hand and foot sole and to investigate whether CEPs reliably detect A-delta fibre abnormalities. METHODS: Swift cold stimuli were applied to the skin with a commercially available thermode, which cooled down from 30 to 25 °C in approximately 0.5 s. CEP latencies (N1, N2 and P2) and amplitudes (N1, N2/P2) were recorded with EEG. Reversible A-fibre function loss was induced by applying a selective A-fibre block at the superficial radial nerve. RESULTS: In all 16 subjects CEPs could be recorded from all locations; N2, P2 mean latencies were 276.4 ± 38.9 and 389.8 ± 52.5 (face), 318.6 ± 31.6 ms and 477.7 ± 43.6 (hand), and 627.6 ± 84.4 and 774.2 ± 94.0 (foot sole). N2/P2 amplitudes were 10.7 ± 4.1, 11.3 ± 4.1 and 7.5 ± 4.1 µV. During A-fibre block no CEPs were detectable in the grand average, which restored 10 min after block removal. CONCLUSIONS: CEPs were reliably recorded in healthy subjects at the hand, face and foot. Experimentally induced reversible A-delta fibre function loss was detected by CEPs. Functional recovery was assessed as well. This study is basis for further CEP evaluation studies and might be the first step for implementing CEPs in clinical routine for the early diagnosis of small-fibre disease. WHAT DOES THIS STUDY ADD?: Cold-evoked potentials are capable of reliably measuring A-delta fibre integrity, loss of function and functional recovery in healthy subjects, which is an essential prerequisite for diagnostic use in patients with small-fibre disease.


Subject(s)
Evoked Potentials/physiology , Pain Perception/physiology , Spinothalamic Tracts/physiology , Adult , Cold Temperature , Face , Female , Foot , Hand , Humans , Male , Middle Aged , Reaction Time , Reference Values , Reproducibility of Results , Young Adult
9.
Clin Pharmacol Ther ; 97(2): 135-42, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25670518

ABSTRACT

Patients with the same disease may suffer from completely different pain symptoms yet receive the same drug treatment. Several studies elucidate neuropathic pain and treatment response in human surrogate pain models. They show promising results toward a patient stratification according to the mechanisms underlying the pain, as reflected in their symptoms. Several promising new drugs produced negative study results in clinical phase III trials. However, retrospective analysis of treatment response based on baseline pain phenotyping could demonstrate positive results for certain subgroups of patients. Thus, a prospective classification of patients according to pain phenotype may play an increasingly important role in personalized treatment of neuropathic pain states. A recent prospective study using stratification based on pain-related sensory abnormalities confirmed the concept of personalized pharmacological treatment of neuropathic pain.


Subject(s)
Analgesics/therapeutic use , Neuralgia/drug therapy , Precision Medicine , Humans , Neuralgia/classification , Pain Measurement/methods , Phenotype
10.
Opt Express ; 22(17): 20366-74, 2014 Aug 25.
Article in English | MEDLINE | ID: mdl-25321245

ABSTRACT

We demonstrate a polarization-managed 8-dimensional modulation format that is time domain coded to reduce inter-channel nonlinearity. Simulation results show a 2.3 dB improvement in maximum net system margin (NSM) relative to polarization multiplexed (PM)-BPSK, and a 1.0 dB improvement relative to time interleaved return-to-zero (RZ)-PM-BPSK, for five WDM channels propagating over 1600 km ELEAF with 90% inline optical dispersion compensation. In contrast to the other modulations considered, the new 8-dimensional format has negligible sensitivity to the polarization states of the neighboring WDM channels. High-density WDM (HD-WDM) measurements on a 5000 km dispersion-managed link show a 1.0 dB improvement in net system margin relative to PM-BPSK.

11.
Bioanalysis ; 5(7): 811-7, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23534425

ABSTRACT

BACKGROUND: Biodistribution of drug and drug candidates offers critical information regarding drug disposition in target and nontarget tissues. Concentrations of therapeutic agents in target tissue provide the foundation for efficacy, while concentrations in nontarget tissue pose potential safety risks. Analysis of tissue samples can sometimes provide important information during the development of a drug candidate, especially at early stages when radio labeled drug material is not readily available. RESULTS: Determining the appropriate approach to allow for accurate, precise and reproducible drug concentration measurements from tissue samples requires addressing issues not present in routinely analyzed biological matrices, that is, plasma. We present here the issues encountered and techniques applied during the development, validation and application of a method for the determination of zotarolimus in a variety of tissues. CONCLUSION: When well controlled, analysis of tissue samples can be performed in a manner similar to liquid biological matrices.


Subject(s)
Chromatography, Liquid/methods , Immunosuppressive Agents/analysis , Sirolimus/analogs & derivatives , Tandem Mass Spectrometry/methods , Animals , Immunosuppressive Agents/pharmacokinetics , Sirolimus/analysis , Sirolimus/blood , Sirolimus/pharmacokinetics , Swine , Validation Studies as Topic
12.
J Ethnopharmacol ; 125(3): 487-93, 2009 Sep 25.
Article in English | MEDLINE | ID: mdl-19577624

ABSTRACT

AIM OF THE STUDY: The purpose of the study was to assess the anti-inflammatory effects of the mushroom Inonotus obliquus (Chaga), Polygala senega (Senega) and Viburnum trilobum (Cranberry) bark extract fractions from locally produced materials in lipopolysaccharide (LPS) induced murine macrophage RAW 164.7 cells. MATERIALS AND METHODS: Four fractions from each of the three extracts were obtained: (80% ethanol extracted; Fa), (water-soluble polysaccharide fraction; Fb), (Polyphenolic fraction; Fc) and (ETOAc/H(2)O extracted fraction; Fd). These extract fractions were tested in the cell screening system at 50,100 and 500 microg/ml for their ability to inhibit LPS induced inflammatory cytokines IL-1beta, TNFalpha and IL-6. Supernatants from LPS alone treated cells were used as control. The cytokines in the cell culture supernatants following treatments with extract fractions were quantified by ELISA method, using 96 well ELISA plates. RESULTS: All fractions of the extracts significantly inhibited (p<0.05) the levels of IL-1beta, IL-6 and TNFalpha except the polyphenolic Fc fraction of Senega which showed an increased production of IL-6. Furthermore, each fraction showed a dose-dependant anti-inflammatory effect. Nitric oxide production was not affected by cranberry and senega, while Chaga significantly reduced NO production in murine macrophage cell assay. CONCLUSIONS: These results demonstrate that the extracts obtained from the root of Polygala senega L., bark of Viburnum trilobum, and the mushroom Inonotus obliquus possess anti-inflammatory properties when tested in a RAW 264.7 macrophage cell system.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Basidiomycota/chemistry , Macrophages/drug effects , Plant Extracts/pharmacology , Polygala/chemistry , Viburnum/chemistry , Animals , Canada , Cell Line , Culture Media/chemistry , Cytokines/analysis , Dose-Response Relationship, Drug , Mice , Nitric Oxide/metabolism , Plant Bark/chemistry , Plant Roots/chemistry , Polygala/anatomy & histology , Viburnum/anatomy & histology
13.
Rapid Commun Mass Spectrom ; 20(22): 3427-34, 2006.
Article in English | MEDLINE | ID: mdl-17051612

ABSTRACT

Drug-eluting stents have attracted significant attention in the medical community and pharmaceutical industry due to their proven success in significantly reducing restenosis. Abbott Laboratories is developing a drug-eluting stent coated with zotarolimus and swine was recently used as an animal model for the pre-clinical study of stent implantation. In this article, we present a detailed experimental design and results for the validation and sample analysis of zotarolimus drug concentration in stented swine artery samples. Introduction of tissue quality control (QC) samples allows evaluation of the entire analytical process as well as the stability of the drug in both original tissue and homogenized tissue samples. In addition, a novel approach using 100% swine blood as the homogenization solution was developed for the consistency of the liquid-liquid extraction recovery and stability of the zotarolimus in tissue homogenates. Standards were prepared by spiking zotarolimus working solution in swine blood and tissue QC samples were used along with the artery samples during the sample analysis. The linear dynamic range of blood standard samples is from 0.61 to 333.20 ng/mL to accommodate the predicted artery homogenate concentrations. Overall tissue QC %CV during the method validation was from 4.4% to 8.6%. The overall %bias of tissue QC samples during the method validation was from -7.3% to 16.6%. The method was successfully applied for the analysis of swine artery samples. A similar approach for method validation and sample analysis has been successfully applied for the analysis of swine myocardium, kidney and liver tissue samples.


Subject(s)
Arteries/chemistry , Chromatography, High Pressure Liquid , Drug Delivery Systems , Immunosuppressive Agents/analysis , Sirolimus/analogs & derivatives , Stents , Tandem Mass Spectrometry/methods , Animals , Arteries/surgery , Drug Stability , Sirolimus/analysis , Spectrometry, Mass, Electrospray Ionization , Swine
14.
J Environ Sci Health B ; 40(4): 605-17, 2005.
Article in English | MEDLINE | ID: mdl-16047883

ABSTRACT

Manure additions to soil may alter soil chemical, physical, and biological characteristics, and thereby change pesticide fate processes in soil. This is the first study to examine the impact of liquid hog manure amendments on glyphosate and trifluralin mineralization in soil. Experiments were conducted in soil microcosms in the laboratory for a total of 332 (glyphosate) and 430 (trifluralin) days. The rate and amount of mineralization of both glyphosate and trifluralin were significantly influenced by the additions of fresh manure to soil in the laboratory and by the history of manure applications in the field. However, the maximum difference in herbicide mineralization between soils that were free of manure application and those amended with manure in the field or in the laboratory was only 6.1% and 7.3% of that initially applied, for trifluralin and glyphosate, respectively. Therefore, we conclude that liquid hog manure application to soil will have no significant effect on the mineralization of glyphosate and trifluralin under field conditions.


Subject(s)
Glycine/analogs & derivatives , Herbicides/analysis , Manure , Soil Pollutants/analysis , Soil/analysis , Trifluralin/analysis , Animals , Dose-Response Relationship, Drug , Environmental Monitoring , Glycine/analysis , Glycine/metabolism , Herbicides/metabolism , Manitoba , Soil Pollutants/metabolism , Swine , Trifluralin/metabolism , Glyphosate
15.
Mech Dev ; 122(9): 998-1007, 2005 Sep.
Article in English | MEDLINE | ID: mdl-15922570

ABSTRACT

Homeodomain transcription factor CnNK-2 seems to play a major role in foot formation in Hydra. Recently, we reported in vitro evidence indicating that CnNK-2 has autoregulatory features and regulates expression of the morphogenetic peptide pedibin. We proposed that CnNK-2 and pedibin synergistically orchestrate foot differentiation processes. Here, we further analyzed the regulatory network controlling foot formation in Hydra. By phylogenetic footprinting we compared the CnNK-2 5'-flanking sequence from two closely related species, Hydra vulgaris and Hydra oligactis. Unexpectedly, we detected a highly conserved binding site for HNF-3beta, a vertebrate Forkhead transcription factor, in the CnNK-2 5'-flanking region. The Hydra HNF-3beta homolog budhead is predominantly expressed in the apical region of the body column and early during budding. Budhead is absent from tissue expressing CnNK-2 and thought to be involved in determining tissue for head differentiation. By electrophoretic mobility shift assays we demonstrate an in vitro interaction between recombinant budhead protein and the interspecific conserved HNF-3beta binding motif in the CnNK-2 5'-flanking region. Our results strengthen the view of CnNK-2 as an important regulator during foot patterning processes. Furtheron, they point to budhead as a candidate for a transcriptional regulator of CnNK-2 and to an interaction of foot and head patterning processes in Hydra on the molecular level.


Subject(s)
Hydra/growth & development , Hydra/genetics , Animals , Base Sequence , Binding Sites/genetics , Body Patterning/genetics , DNA/genetics , DNA/metabolism , DNA Footprinting , Gene Expression Regulation, Developmental , Homeodomain Proteins/genetics , Homeodomain Proteins/metabolism , Hydra/metabolism , Models, Biological , Phylogeny , Promoter Regions, Genetic , Transcription Factors/genetics , Transcription Factors/metabolism
16.
Article in English | MEDLINE | ID: mdl-15113541

ABSTRACT

We report here a quantitative method for the analysis of ABT-578 in human whole blood samples. Sample preparation was achieved by a semi-automated 96-well format liquid-liquid extraction (LLE) method. Aluminum/polypropylene heat seal foil was used to enclose each well of the 96-well plate for the liquid-liquid extraction. A liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) method with pre-column regeneration was developed for the analysis of sample extracts. Selective reaction monitoring (SRM) of the mass transitions m/z 983-935 and m/z 931-883 was employed for the detection of ABT-578 and internal standard, respectively. The ammonium adduct ions [M + NH(4)](+) generated from electrospray ionization were monitored as the precursor ions. The assay was validated for a linear dynamic range of 0.20-200.75ng/ml. The correlation coefficient (r) was between 0.9959 and 0.9971. The intra-assay CV (%) was between 1.9 and 13.5% and the inter-assay CV (%) was between 4.7 and 11.3%. The inter-assay mean accuracy was between 86.4 and 102.5% of the theoretical concentrations.


Subject(s)
Chromatography, Liquid/methods , Sirolimus/analogs & derivatives , Sirolimus/blood , Spectrometry, Mass, Electrospray Ionization/methods , Humans , Reference Standards , Reproducibility of Results , Sensitivity and Specificity
17.
Pflugers Arch ; 444(4): 556-67, 2002 Jul.
Article in English | MEDLINE | ID: mdl-12136276

ABSTRACT

The cAMP-elevating pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates insulin release in pancreatic B-cells. Here, we have investigated its potentiating action in rat insulinoma INS-1 cells. In intact cells, PACAP-27 (100 nM) stimulated glucose-induced insulin secretion by >60%. Using the patch-clamp technique with single-cell exocytosis monitored as increases in cell capacitance, we observed that at 10 mM and 20 mM extracellular glucose, PACAP-27 acted mainly by a >50% enhancement of depolarization-elicited Ca(2+) entry, whereas at low (3 mM) glucose, the predominant effect of the peptide was a twofold increase in Ca(2+) sensitivity of insulin exocytosis. The latter effect was mimicked by glucose itself in a dose-dependent fashion. PACAP-27 exerts a prolonged effect on insulin secretion that is dissociated from changes of cytoplasmic cAMP. Whereas an elevation of cellular cAMP content (135%) could be observed 2 min after addition of PACAP-27, after 30 min preincubation with the peptide, cAMP concentrations were not different from basal. Yet, such pretreatment with PACAP-27 stimulated subsequent insulin release by congruent with60%. This sustained action is likely to reflect an increased degree of protein-kinase-A-dependent phosphorylation, and inhibitors of the kinase largely prevented the PACAP-mediated effects.


Subject(s)
Cyclic AMP/analysis , Insulin/metabolism , Islets of Langerhans/metabolism , Neuropeptides/pharmacology , Neurotransmitter Agents/pharmacology , Action Potentials/drug effects , Action Potentials/physiology , Animals , Calcium/metabolism , Calcium Channels/metabolism , Cyclic AMP-Dependent Protein Kinases/metabolism , Electrophysiology , Exocytosis/drug effects , Glucagon/pharmacology , Glucagon-Like Peptide 1 , Glucose/pharmacology , Insulin Secretion , Insulinoma/metabolism , Islets of Langerhans/drug effects , Pancreatic Neoplasms/metabolism , Patch-Clamp Techniques , Peptide Fragments/pharmacology , Pituitary Adenylate Cyclase-Activating Polypeptide , Protein Precursors/pharmacology , Rats , Tumor Cells, Cultured
18.
Eur J Endocrinol ; 146(5): 717-27, 2002 May.
Article in English | MEDLINE | ID: mdl-11980629

ABSTRACT

OBJECTIVES: Inhibitors of the glucagon-like peptide-1 (GLP-1)-degrading enzyme, dipeptidyl peptidase IV (DPPIV), are being explored in the treatment of diabetes. We examined the long-term influence of a selective, orally active inhibitor of DPPIV (NVP DPP728), in normal female C57BL/6J mice and such mice rendered glucose-intolerant and insulin-resistant by feeding a high-fat diet. DESIGN: In mice fed a standard diet (11% fat) or a high-fat diet (58% fat), NVP DPP728 (0.12 micromol/g body weight) was administered in the drinking water for an 8 week period. RESULTS: DPPIV inhibition reduced plasma DPPIV activity to 0.01+/-0.03 mU/ml vs 3.26+/-0.19 mU/ml in controls (P<0.001). Glucose tolerance after gastric glucose gavage, as judged by the area under the curve for plasma glucose levels over the 120 min study period, was increased after 8 weeks by NVP DPP728 in mice fed normal diet (P=0.029) and in mice fed a high-fat diet (P=0.036). This was accompanied by increased plasma levels of insulin and intact GLP-1. Glucose-stimulated insulin secretion from islets isolated from NVP DPP728-treated animals after 8 weeks of treatment was increased as compared with islets from control animals at 5.6, 8.3 and 11.1 mmol/l glucose both in mice fed normal diet and in mice fed a high-fat diet (both P<0.05). Islet insulin and glucagon immunocytochemistry revealed that NVP DPP728 did not affect the islet architecture. However, the expression of immunoreactive glucose transporter isoform-2 (GLUT-2) was increased by DPPIV inhibition, and in mice fed a high-fat diet, islet size was reduced after treatment with NVP DPP728 from 16.7+/-2.6 x 10(3) microm(2) in controls to 7.6+/-1.0 x 10(3) microm(2) (P=0.0019). CONCLUSION: Long-term DPPIV inhibition improves glucose tolerance in both normal and glucose-intolerant mice through improved islet function as judged by increased GLUT-2 expression, increased insulin secretion and protection from increased islet size in insulin resistance.


Subject(s)
Dipeptidyl Peptidase 4/drug effects , Glucose Intolerance/drug therapy , Islets of Langerhans/drug effects , Islets of Langerhans/physiology , Nitriles/therapeutic use , Protease Inhibitors/therapeutic use , Pyrrolidines/therapeutic use , Animals , Blood Glucose/analysis , Body Weight , Dietary Fats/administration & dosage , Dipeptidyl Peptidase 4/blood , Drinking , Eating , Female , Glucagon/blood , Glucagon-Like Peptide 1 , Glucose/administration & dosage , Glucose/pharmacology , Insulin/blood , Insulin Resistance/physiology , Intubation, Gastrointestinal , Islets of Langerhans/anatomy & histology , Mice , Mice, Inbred C57BL , Organ Size/drug effects , Peptide Fragments/blood , Protein Precursors/blood , Time Factors
19.
Can J Nurs Res ; 33(4): 155-69, 2002 Mar.
Article in English | MEDLINE | ID: mdl-11998193

ABSTRACT

The demand for and use of health, social, and other human services is related not to the type or severity of disease but rather to a person's socio-economic, cognitive, and emotional characteristics and environmental circumstances. A workshop on supportive care was held to promote a robust research environment, the creation of new knowledge, the setting of an integrated health research agenda, a focusing of attention on the evolving health-care system, and anticipation of emerging health challenges. While the workshop was intended to address a research mandate for the Canadian Institutes of Health Research, a larger vision emerged, to include advocacy, information system, surveillance, and policy development required by institutional, community, voluntary, private sector, family caregiver, and provider systems. The development of a national supportive care strategy will enable Canadians with disease and disability to live with all of their challenges, and could engage researchers, clinicians, advocacy groups, and people experiencing major health challenges.


Subject(s)
Chronic Disease/therapy , Health Planning , Health Services Research , Neoplasms/therapy , Canada , Humans
20.
Diabetes ; 50(9): 1959-69, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11522660

ABSTRACT

The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is ubiquitously distributed in both the central and peripheral nervous systems and exerts a variety of effects. PACAP is a neuropeptide in pancreatic islets, where it has been suggested as a parasympathetic and sensory neurotransmitter. PACAP stimulates insulin secretion in a glucose-dependent manner, by an effect executed mainly through augmenting the formation of cAMP and stimulating the uptake of calcium. Accumulating evidence in animal studies points to a physiological importance of PACAP in the regulation of the insulin response to feeding. This review summarizes the current knowledge of islet actions and mechanisms and the function of PACAP.


Subject(s)
Islets of Langerhans/physiology , Neuropeptides/physiology , Animals , Hormones/metabolism , Humans , Pituitary Adenylate Cyclase-Activating Polypeptide , Signal Transduction
SELECTION OF CITATIONS
SEARCH DETAIL
...