Publications by authors named "Malin Andersson"

44 Publications

Population-scale single-cell RNA-seq profiling across dopaminergic neuron differentiation.

Nat Genet 2021 03 4;53(3):304-312. Epub 2021 Mar 4.

Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK.

Studying the function of common genetic variants in primary human tissues and during development is challenging. To address this, we use an efficient multiplexing strategy to differentiate 215 human induced pluripotent stem cell (iPSC) lines toward a midbrain neural fate, including dopaminergic neurons, and use single-cell RNA sequencing (scRNA-seq) to profile over 1 million cells across three differentiation time points. The proportion of neurons produced by each cell line is highly reproducible and is predictable by robust molecular markers expressed in pluripotent cells. Expression quantitative trait loci (eQTL) were characterized at different stages of neuronal development and in response to rotenone-induced oxidative stress. Of these, 1,284 eQTL colocalize with known neurological trait risk loci, and 46% are not found in the Genotype-Tissue Expression (GTEx) catalog. Our study illustrates how coupling scRNA-seq with long-term iPSC differentiation enables mechanistic studies of human trait-associated genetic variants in otherwise inaccessible cell states.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41588-021-00801-6DOI Listing
March 2021

Signs of neuroaxonal injury in preeclampsia-A case control study.

PLoS One 2021 8;16(2):e0246786. Epub 2021 Feb 8.

Department of Obstetrics and Gynecology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

Background: Cerebral injury is a common cause of maternal mortality due to preeclampsia and is challenging to predict and diagnose. In addition, there are associations between previous preeclampsia and stroke, dementia and epilepsy later in life. The cerebral biomarkers S100B, neuron specific enolase, (NSE), tau protein and neurofilament light chain (NfL) have proven useful as predictors and diagnostic tools in other neurological disorders. This case-control study sought to determine whether cerebral biomarkers were increased in cerebrospinal fluid (CSF) as a marker of cerebral origin and potential cerebral injury in preeclampsia and if concentrations in CSF correlated to concentrations in plasma.

Methods: CSF and blood at delivery from 15 women with preeclampsia and 15 women with normal pregnancies were analysed for the cerebral biomarkers S100B, NSE, tau protein and NfL by Simoa and ELISA based methods. MRI brain was performed after delivery and for women with preeclampsia also at six months postpartum.

Results: Women with preeclampsia demonstrated increased CSF- and plasma concentrations of NfL and these concentrations correlated to each other. CSF concentrations of NSE and tau were decreased in preeclampsia and there were no differences in plasma concentrations of NSE and tau between groups. For S100B, serum concentrations in preeclampsia were increased but there was no difference in CSF concentrations of S100B between women with preeclampsia and normal pregnancy.

Conclusion: NfL emerges as a promising circulating cerebral biomarker in preeclampsia and increased CSF concentrations point to a neuroaxonal injury in preeclampsia, even in the absence of clinically evident neurological complications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246786PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7869986PMC
February 2021

Co-Constructing Universal Design in Citizen Science Workshops.

Stud Health Technol Inform 2018 ;256:214-222

Lund University.

This paper reports on a series of workshops that took place at two Swedish museums during 2017. The workshops were inspired by a citizen science approach, where the participants were not only on the receiving end but also active in producing new knowledge. The importance of turning to peoples' lived perspectives are often brought forward as crucial to understanding how inclusion and exclusion are played out in real life. The study aimed to introduce and discuss Universal Design (UD) of museum exhibitions, by engaging visitors and staff in bringing forward content for joint discussions. As there is an ongoing shift from traditional work on accessibility towards UD taking place in Sweden right now, the study was also part of raising the awareness of UD within the disability movement and at the museums. Museum visitors representing different disability organizations worked together with museum staff in photo exercises, supervised by two researchers. In total, 31 participants took part in six three-hour workshops. The workshop format encompassed three steps. First, one of the researchers introduced UD, after which the participants were divided into mixed groups with both visitors and staff. Their task was to take photos of museum features that were in line with, or in conflict with, UD. At the end of the workshop, all groups gathered to discuss what they had found. In this paper, we tell about the examples the participants brought forward and the ensuing joint discussions, and discuss the further implications for UD.
View Article and Find Full Text PDF

Download full-text PDF

Source
August 2019

Geosphere-biosphere circulation of chemical elements in soil and plant systems from a 100 km transect from southern central Norway.

Sci Total Environ 2018 Oct 26;639:129-145. Epub 2018 May 26.

Faculty of Life Science, University of Vienna, Althanstr. 14, A-1090 Vienna, Austria.

Geochemical element separation is studied in 14 different sample media collected at 41 sites along an approximately 100-km long transect north of Oslo. At each site, soil C and O horizons and 12 plant materials (birch/spruce/cowberry/blueberry leaves/needles and twigs, horsetail, braken fern, pine bark and terrestrial moss) were sampled. The observed concentrations of 29 elements (K, Ca, P, Mg, Mn, S, Fe, Zn, Na, B, Cu, Mo, Co, Al, Ba, Rb, Sr, Ti, Ni, Pb, Cs, Cd, Ce, Sn, La, Tl, Y, Hg, Ag) were used to investigate soil-plant relations, and to evaluate the element differentiation between different plants, or between foliage and twigs of the same plant. In relation to the soil C horizon, the O horizon is strongly enriched (O/C ratio > 5) in Ag, Hg, Cd, Sn, S and Pb. Other elements (B, K, Ca, P, S, Mn) show higher concentrations in the plants than in the substrate represented by the C horizon, and often even higher concentrations than in the soil O horizon. Elements like B, K, Ca, S, Mg, P, Ba, and Cu are well tuned to certain concentration levels in most of the plants. This is demonstrated by their lower interquartile variability in the plants than in the soil. Cross-plots of element concentration, variance, and ratios, supported by linear discrimination analysis, establish that different plants are marked by their individual element composition, which is separable from, and largely independent of the natural substrate variability across the Gjøvik transect. Element allocation to foliage or twigs of the same plants can also be separated and thus dominantly depend on metabolism, physiology, and structure linked to biological functions, and only to a lesser degree on the substrate and environmental background. The results underline the importance of understanding the biological mechanisms of plant-soil interaction in order to correctly quantify anthropogenic impact on soil and plant geochemistry.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2018.05.070DOI Listing
October 2018

Influence of Multiple Environmental Factors on Organic Matter Chlorination in Podsol Soil.

Environ Sci Technol 2017 Dec 12;51(24):14114-14123. Epub 2017 Dec 12.

Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden.

Natural chlorination of organic matter is common in soils. The abundance of chlorinated organic compounds frequently exceeds chloride in surface soils, and the ability to chlorinate soil organic matter (SOM) appears widespread among microorganisms. Yet, the environmental control of chlorination is unclear. Laboratory incubations with Cl as a Cl tracer were performed to test how combinations of environmental factors, including levels of soil moisture, nitrate, chloride, and labile organic carbon, influenced chlorination of SOM from a boreal forest. Total chlorination was hampered by addition of nitrate or by nitrate in combination with water but enhanced by addition of chloride or most additions including labile organic matter (glucose and maltose). The greatest chlorination was observed after 15 days when nitrate and water were added together with labile organic matter. The effect that labile organic matter strongly stimulated the chlorination rates was confirmed by a second independent experiment showing higher stimulation at increased availability of labile organic matter. Our results highlight cause-effect links between chlorination and the studied environmental variables in podsol soil-with consistent stimulation by labile organic matter that did overrule the negative effects of nitrate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.7b03196DOI Listing
December 2017

Macrophage migration inhibitory factor (MIF) modulates trophic signaling through interaction with serine protease HTRA1.

Cell Mol Life Sci 2017 12 19;74(24):4561-4572. Epub 2017 Jul 19.

Department of Molecular Medicine-Neurobiology Research, University of Southern Denmark, J.B. Winslows Vej 21.1, 5000, Odense, Denmark.

Macrophage migration inhibitory factor (MIF), a small conserved protein, is abundant in the immune- and central nervous system (CNS). MIF has several receptors and binding partners that can modulate its action on a cellular level. It is upregulated in neurodegenerative diseases and cancer although its function is far from clear. Here, we report the finding of a new binding partner to MIF, the serine protease HTRA1. This enzyme cleaves several growth factors, extracellular matrix molecules and is implicated in some of the same diseases as MIF. We show that the function of the binding between MIF and HTRA1 is to inhibit the proteolytic activity of HTRA1, modulating the availability of molecules that can change cell growth and differentiation. MIF is therefore the first endogenous inhibitor ever found for HTRA1. It was found that both molecules were present in astrocytes and that the functional binding has the ability to modulate astrocytic activities important in development and disease of the CNS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00018-017-2592-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663815PMC
December 2017

Neuropeptide imaging in rat spinal cord with MALDI-TOF MS: Method development for the application in pain-related disease studies.

Eur J Mass Spectrom (Chichester) 2017 Jun 7;23(3):105-115. Epub 2017 May 7.

1 Analytical Chemistry, Department of Chemistry - BMC, Uppsala University, Uppsala, Sweden.

Spinal cord as a connection between brain and peripheral nervous system is an essential material for studying neural transmission, especially in pain-related research. This study was the first to investigate pain-related neuropeptide distribution in rat spinal cord using a matrix-assisted laser desorption ionization-time of flight imaging mass spectrometry (MALDI TOF MS) approach. The imaging workflow was evaluated and showed that MALDI TOF MS provides efficient resolution and robustness for neuropeptide imaging in rat spinal cord tissue. The imaging result showed that in naive rat spinal cord the molecular distribution of haeme, phosphatidylcholine, substance P and thymosin beta 4 were well in line with histological features. Three groups of pain-related neuropeptides, which are cleaved from prodynorphin, proenkephalin and protachykinin-1 proteins were detected. All these neuropeptides were found predominantly localized in the dorsal spinal cord and each group had unique distribution pattern. This study set the stage for future MALDI TOF MS application to elucidate signalling mechanism of pain-related diseases in small animal models.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1469066717703272DOI Listing
June 2017

Intra- and interregional coregulation of opioid genes: broken symmetry in spinal circuits.

FASEB J 2017 05 25;31(5):1953-1963. Epub 2017 Jan 25.

Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.

Regulation of the formation and rewiring of neural circuits by neuropeptides may require coordinated production of these signaling molecules and their receptors that may be established at the transcriptional level. Here, we address this hypothesis by comparing absolute expression levels of opioid peptides with their receptors, the largest neuropeptide family, and by characterizing coexpression (transcriptionally coordinated) patterns of these genes. We demonstrated that expression patterns of opioid genes highly correlate within and across functionally and anatomically different areas. Opioid peptide genes, compared with their receptor genes, are transcribed at much greater absolute levels, which suggests formation of a neuropeptide cloud that covers the receptor-expressed circuits. Surprisingly, we found that both expression levels and the proportion of opioid receptors are strongly lateralized in the spinal cord, interregional coexpression patterns are side specific, and intraregional coexpression profiles are affected differently by left- and right-side unilateral body injury. We propose that opioid genes are regulated as interconnected components of the same molecular system distributed between distinct anatomic regions. The striking feature of this system is its asymmetric coexpression patterns, which suggest side-specific regulation of selective neural circuits by opioid neurohormones.-Kononenko, O., Galatenko, V., Andersson, M., Bazov, I., Watanabe, H., Zhou, X. W., Iatsyshyna, A., Mityakina, I., Yakovleva, T., Sarkisyan, D., Ponomarev, I., Krishtal, O., Marklund, N., Tonevitsky, A., Adkins, D. L., Bakalkin, G. Intra- and interregional coregulation of opioid genes: broken symmetry in spinal circuits.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1096/fj.201601039RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5388547PMC
May 2017

Region-specific bioconversion of dynorphin neuropeptide detected by in situ histochemistry and MALDI imaging mass spectrometry.

Peptides 2017 01 10;87:20-27. Epub 2016 Nov 10.

Department of Pharmaceutical Biosciences, Uppsala University, Uppsala 751 24, Sweden. Electronic address:

Brain region-specific expression of proteolytic enzymes can control the biological activity of endogenous neuropeptides and has recently been targeted for the development of novel drugs, for neuropathic pain, cancer, and Parkinson's disease. Rapid and sensitive analytical methods to profile modulators of enzymatic activity are important for finding effective inhibitors with high therapeutic value. Combination of in situ enzyme histochemistry with MALDI imaging mass spectrometry allowed developing a highly sensitive method for analysis of brain-area specific neuropeptide conversion of synthetic and endogenous neuropeptides, and for selection of peptidase inhibitors that differentially target conversion enzymes at specific anatomical sites. Conversion and degradation products of Dynorphin B as model neuropeptide and effects of peptidase inhibitors applied to native brain tissue sections were analyzed at different brain locations. Synthetic dynorphin B (2pmol) was found to be converted to the N-terminal fragments on brain sections whereas fewer C-terminal fragments were detected. N-ethylmaleimide (NEM), a non-selective inhibitor of cysteine peptidases, almost completely blocked the conversion of dynorphin B to dynorphin B(1-6; Leu-Enk-Arg), (1-9), (2-13), and (7-13). Proteinase inhibitor cocktail, and also incubation with acetic acid displayed similar results. Bioconversion of synthetic dynorphin B was region-specific producing dynorphin B(1-7) in the cortex and dynorphin B (2-13) in the striatum. Enzyme inhibitors showed region- and enzyme-specific inhibition of dynorphin bioconversion. Both phosphoramidon (inhibitor of the known dynorphin converting enzyme neprilysin) and opiorphin (inhibitor of neprilysin and aminopeptidase N) blocked cortical bioconversion to dynorphin B(1-7), wheras only opiorphin blocked striatal bioconversion to dynorphin B(2-13). This method may impact the development of novel therapies with aim to strengthen the effects of endogenous neuropeptides under pathological conditions such as chronic pain. Combining histochemistry and MALDI imaging MS is a powerful and sensitive tool for the study of inhibition of enzyme activity directly in native tissue sections.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.peptides.2016.11.006DOI Listing
January 2017

Opioid precursor protein isoform is targeted to the cell nuclei in the human brain.

Biochim Biophys Acta Gen Subj 2017 Feb 10;1861(2):246-255. Epub 2016 Nov 10.

Department of Pharmaceutical Biosciences, Uppsala University, Uppsala 751 24, Sweden.

Background: Neuropeptide precursors are traditionally viewed as proteins giving rise to small neuropeptide molecules. Prodynorphin (PDYN) is the precursor protein to dynorphins, endogenous ligands for the κ-opioid receptor. Alternative mRNA splicing of neuropeptide genes may regulate cell- and tissue-specific neuropeptide expression and produce novel protein isoforms. We here searched for novel PDYN mRNA and their protein product in the human brain.

Methods: Novel PDYN transcripts were identified using nested PCR amplification of oligo(dT) selected full-length capped mRNA. Gene expression was analyzed by qRT-PCR, PDYN protein by western blotting and confocal imaging, dynorphin peptides by radioimmunoassay. Neuronal nuclei were isolated using fluorescence-activated nuclei sorting (FANS) from postmortem human striatal tissue. Immunofluorescence staining and confocal microscopy was performed for human caudate nucleus.

Results: Two novel human PDYN mRNA splicing variants were identified. Expression of one of them was confined to the striatum where its levels constituted up to 30% of total PDYN mRNA. This transcript may be translated into ∆SP-PDYN protein lacking 13 N-terminal amino acids, a fragment of signal peptide (SP). ∆SP-PDYN was not processed to mature dynorphins and surprisingly, was targeted to the cell nuclei in a model cellular system. The endogenous PDYN protein was identified in the cell nuclei in human striatum by western blotting of isolated neuronal nuclei, and by confocal imaging.

Conclusions And General Significance: High levels of alternatively spliced ∆SP-PDYN mRNA and nuclear localization of PDYN protein suggests a nuclear function for this isoform of the opioid peptide precursor in human striatum.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbagen.2016.11.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5323248PMC
February 2017

Reduced Gene Expression Levels throughout the Mouse Subthalamic Nucleus Cause Cell Loss and Structural Disorganization Followed by Increased Motor Activity and Decreased Sugar Consumption.

eNeuro 2016 Sep-Oct;3(5). Epub 2016 Sep 29.

Department of Organismal Biology, Uppsala University , SE-752 36 Uppsala, Sweden.

The subthalamic nucleus (STN) plays a central role in motor, cognitive, and affective behavior. Deep brain stimulation (DBS) of the STN is the most common surgical intervention for advanced Parkinson's disease (PD), and STN has lately gained attention as target for DBS in neuropsychiatric disorders, including obsessive compulsive disorder, eating disorders, and addiction. Animal studies using STN-DBS, lesioning, or inactivation of STN neurons have been used extensively alongside clinical studies to unravel the structural organization, circuitry, and function of the STN. Recent studies in rodent STN models have exposed different roles for STN neurons in reward-related functions. We have previously shown that the majority of STN neurons express the vesicular glutamate transporter 2 gene () and that reduction of Vglut2 mRNA levels within the STN of mice [conditional knockout (cKO)] causes reduced postsynaptic activity and behavioral hyperlocomotion. The cKO mice showed less interest in fatty rewards, which motivated analysis of reward-response. The current results demonstrate decreased sugar consumption and strong rearing behavior, whereas biochemical analyses show altered dopaminergic and peptidergic activity in the striatum. The behavioral alterations were in fact correlated with opposite effects in the dorsal versus the ventral striatum. Significant cell loss and disorganization of the STN structure was identified, which likely accounts for the observed alterations. Rare genetic variants of the human gene exist, and this study shows that reduced gene expression levels exclusively within the STN of mice is sufficient to cause strong modifications in both the STN and the mesostriatal dopamine system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/ENEURO.0264-16.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5041164PMC
October 2017

Quantitative mass spectrometry imaging of small-molecule neurotransmitters in rat brain tissue sections using nanospray desorption electrospray ionization.

Analyst 2016 Jun;141(12):3686-95

Department of Chemistry-BMC, Uppsala University, Uppsala, Sweden.

Small molecule neurotransmitters are essential for the function of the nervous system, and neurotransmitter imbalances are often connected to neurological disorders. The ability to quantify such imbalances is important to provide insights into the biochemical mechanisms underlying the disorder. This proof-of-principle study presents online quantification of small molecule neurotransmitters, specifically acetylcholine, γ-aminobutyric acid (GABA) and glutamate, in rat brain tissue sections using nanospray desorption electrospray ionization (nano-DESI) mass spectrometry imaging. By incorporating deuterated internal standards in the nano-DESI solvent we show identification, accurate mapping, and quantification of these small neurotransmitters in rat brain tissue without introducing any additional sample preparation steps. We find that GABA is about twice as abundant in the medial septum-diagonal band complex (MSDB) as in the cortex, while glutamate is about twice as abundant in the cortex as compared to the MSDB. The study shows that nano-DESI is well suited for imaging of small molecule neurotransmitters in health and disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c5an02620bDOI Listing
June 2016

How to measure renal artery stenosis--a retrospective comparison of morphological measurement approaches in relation to hemodynamic significance.

BMC Med Imaging 2015 Oct 12;15:42. Epub 2015 Oct 12.

Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.

Background: Although it is well known that renal artery stenosis may cause renovascular hypertension, it is unclear how the degree of stenosis should best be measured in morphological images. The aim of this study was to determine which morphological measures from Computed Tomography Angiography (CTA) and Magnetic Resonance Angiography (MRA) are best in predicting whether a renal artery stenosis is hemodynamically significant or not.

Methods: Forty-seven patients with hypertension and a clinical suspicion of renovascular hypertension were examined with CTA, MRA, captopril-enhanced renography (CER) and captopril test (Ctest). CTA and MRA images of the renal arteries were analyzed by two readers using interactive vessel segmentation software. The measures included minimum diameter, minimum area, diameter reduction and area reduction. In addition, two radiologists visually judged the diameter reduction without automated segmentation. The results were then compared using limits of agreement and intra-class correlation, and correlated with the results from CER combined with Ctest (which were used as standard of reference) using receiver operating characteristics (ROC) analysis.

Results: A total of 68 kidneys had all three investigations (CTA, MRA and CER + Ctest), where 11 kidneys (16.2 %) got a positive result on the CER + Ctest. The greatest area under ROC curve (AUROC) was found for the area reduction on MRA, with a value of 0.91 (95 % confidence interval 0.82-0.99), excluding accessory renal arteries. As comparison, the AUROC for the radiologists' visual assessments on CTA and MRA were 0.90 (0.82-0.98) and 0.91 (0.83-0.99) respectively. None of the differences were statistically significant.

Conclusions: No significant differences were found between the morphological measures in their ability to predict hemodynamically significant stenosis, but a tendency of MRA having higher AUROC than CTA. There was no significant difference between measurements made by the radiologists and measurements made with fuzzy connectedness segmentation. Further studies are required to definitely identify the optimal measurement approach.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12880-015-0086-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4601150PMC
October 2015

Submarine and deep-sea mine tailing placements: A review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally.

Mar Pollut Bull 2015 Aug 1;97(1-2):13-35. Epub 2015 Jun 1.

Marine Biology Research Group, Ghent University, Krijgslaan 281, B-9000 Gent, Belgium. Electronic address:

The mining sector is growing in parallel with societal demands for minerals. One of the most important environmental issues and economic burdens of industrial mining on land is the safe storage of the vast amounts of waste produced. Traditionally, tailings have been stored in land dams, but the lack of land availability, potential risk of dam failure and topography in coastal areas in certain countries results in increasing disposal of tailings into marine systems. This review describes the different submarine tailing disposal methods used in the world in general and in Norway in particular, their impact on the environment (e.g. hyper-sedimentation, toxicity, processes related to changes in grain shape and size, turbidity), current legislation and need for future research. Understanding these impacts on the habitat and biota is essential to assess potential ecosystem changes and to develop best available techniques and robust management plans.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.marpolbul.2015.05.062DOI Listing
August 2015

Urban contamination sources reflected in inorganic pollution in urban lake deposits, Bergen, Norway.

Environ Sci Process Impacts 2015 Apr;17(4):854-67

Geological Survey of Norway (NGU), Postboks 6315 Sluppen, 7491 Trondheim, Norway.

The 7000 years transition from a pristine environment towards a modern city has brought a number of chemical changes and effects to urban lake sediments in Bergen. Metals, such as Pb, Hg, Zn, Cu and Fe, display a large anthropogenic influence and reflect historical point sources that existed within the drainage area from approximately AD 1790 until today. The concentration peaks alternate with intervals of lower concentration due to phases of coarser grained sediment input but also periods of potentially reduced metal influx. All discussed elements, except Cd, increase in concentration with decreasing grain size and also correlate with the amount of clay fraction particles. The results emphasize the importance of considering grain size when interpreting sediment chemistry. Correlation with TOC is not apparent in the same extent. The transition from natural to anthropogenically influenced sediments, which is characterised by a sudden increase of several elements, is accompanied by a reduction in Cd, As and Ni concentration. This is interpreted to be the result of hypoxia, changes in pH and reduced erosional input. Factor analysis and the comparison with reference sediments indicate that the elements Pb, Hg, Zn and Cu most clearly demonstrate man-made pollution. Analyses of stormwater culvert sediments suggest that urban runoff contributes to the pollution load today, with standing building mass and traffic contributing to the load.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c4em00614cDOI Listing
April 2015

Polycyclic aromatic hydrocarbons (PAHs) in sediments from lake Lille Lungegårdsvannet in Bergen, western Norway; appraising pollution sources from the urban history.

Sci Total Environ 2014 Feb 16;470-471:1160-72. Epub 2013 Nov 16.

Geological Survey of Norway (NGU), Postboks 6315 Sluppen, 7491 Trondheim, Norway.

This study aims to determine the temporal character and concentration variability of polycyclic aromatic hydrocarbon (PAH) during the last 5,400 years in urban lake sediments through a combination of dating and chemo-stratigraphical correlation. We investigate the chemical history of the city of Bergen and determine the effect of specific point sources, as well as diffuse sources, and also help assess the risk of remediation plans. By using several organic compounds, metals and cyanide, we demonstrate the more accurate timing of sedimentation. The PAH results display very low concentrations in pre-industrial times, followed by a general increase that is punctuated by a few significant concentration increases. These most probably correspond to urban fires, domestic heating, gaswork activity and most recently due to traffic pollution. At the same depth as a significant rise in concentration from background levels occurred, the high relative occurrence of low-molecular-weight PAH-compounds, such as naphthalene, were replaced by heavier compounds, thus indicating a permanent change in source. The general observation, using ratios, is that the sources have shifted from pre-industrial pure wood and coal combustion towards mixed and petrogenic sources in more recent times. The (14)C dating provides evidence that the sedimentation rate stayed more-or-less constant for 4,500 years (from 7200 to 2700 calibrated years before present (calyr BP)), before isostatic uplift isolated the water body and the sedimentation rate decreased or sediments were eroded. The sediment input increased again when habitation and industrial activities encroached on the lake. The (14)C dating does not provide consistent data in that period, possibly due to the fact that the lake has been used as a waste site throughout the history of Bergen city. Therefore, results from (14)C dating from anthropogenically influenced sediments should be used with caution.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2013.10.086DOI Listing
February 2014

Quality measures of imaging mass spectrometry aids in revealing long-term striatal protein changes induced by neonatal exposure to the cyanobacterial toxin β-N-methylamino-L-alanine (BMAA).

Mol Cell Proteomics 2014 Jan 14;13(1):93-104. Epub 2013 Oct 14.

Department of Pharmaceutical Biosciences, Uppsala University, 751 24 Uppsala, Sweden;

Many pathological processes are not directly correlated to dramatic alterations in protein levels. The changes in local concentrations of important proteins in a subset of cells or at specific loci are likely to play a significant role in disease etiologies, but the precise location might be unknown, or the concentration might be too small to be adequately sampled for traditional proteomic techniques. Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is a unique analytical method that combines analysis of multiple molecular species and of their distribution in a single platform. As reproducibility is essential for successful biomarker discovery, it is important to systematically assess data quality in biologically relevant MALDI IMS experiments. In the present study, we applied four simple tools to study the reproducibility for individual sections, within-group variation, and between-group variation of data acquired from brain sections of 21 animals divided into three treatment groups. We also characterized protein changes in distinct regions of the striatum from six-month-old rats treated neonatally (postnatal days 9-10) with the cyanobacterial toxin β-N-methylamino-l-alanine (BMAA), which has been implicated in neurodegenerative diseases. The results showed that optimized experimental settings can yield high-quality MALDI IMS data with relatively low variation (14% to 15% coefficient of variance) that allow the characterization of subtle changes in protein expression in various subregions of the brain. This was further exemplified by the dose-dependent reduction of myelin basic protein in the caudate putamen and the nucleus accumbens of adult rats neonatally treated with BMAA (150 and 460 mg/kg). The reduction in myelin basic protein was confirmed through immunohistochemistry and indicates that developmental exposure to BMAA may induce structural effects on axonal growth and/or directly on the proliferation of oligodendrocytes and myelination, which might be important for the previously shown BMAA-induced long-term cognitive impairments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/mcp.M113.031435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3879633PMC
January 2014

Analysis of neuropeptides by MALDI imaging mass spectrometry.

Methods Mol Biol 2013 ;1023:121-36

Department of Pharmaceutical Bioscience, Drug safety and Toxicology, Uppsala University, Uppsala, Sweden.

Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is one of the most effective tools for localizing small molecules and compounds directly in thin tissue sections. MALDI IMS should be used when the distribution of molecular species is not known and to localize changes due to a disease process or a treatment. In recent years it has become increasingly clear that many pathological processes are not readily correlated to dramatic changes in protein levels. MALDI IMS can aid the localization of areas where the cellular concentration of proteins may be high enough to play an important biological role, but when the precise location is unknown. Here, we present a MALDI IMS protocol and data analysis of molecular imaging of multiple rat brain sections.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-1-4614-7209-4_7DOI Listing
January 2014

MALDI imaging of post-mortem human spinal cord in amyotrophic lateral sclerosis.

J Neurochem 2013 Mar 28;124(5):695-707. Epub 2013 Jan 28.

Department of Chemical and Biological Engineering, Analytical Chemistry, Chalmers University of Technology, Gothenburg, Sweden.

Amyotrophic lateral sclerosis (ALS) is a devastating, rapidly progressing disease of the central nervous system that is characterized by motor neuron degeneration in the brainstem and the spinal cord. Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry is an emerging powerful technique that allows for spatially resolved, comprehensive, and specific characterization of molecular species in situ. In this study, we report for the first time the MALDI imaging-based spatial protein profiling and relative quantification of post-mortem human spinal cord samples obtained from ALS patients and controls. In normal spinal cord, protein distribution patterns were well in line with histological features. For example, thymosin beta 4, ubiquitin, histone proteins, acyl-CoA-binding protein, and macrophage inhibitory factor were predominantly localized to the gray matter. Furthermore, unsupervised statistics revealed a significant reduction of two protein species in ALS gray matter. One of these proteins (m/z 8451) corresponds to an endogenous truncated form of ubiquitin (Ubc 1-76), with both C-terminal glycine residues removed (Ubc-T/Ubc 1-74). This region-specific ubiquitin processing suggests a disease-related change in protease activity. These results highlight the importance of MALDI mass spectrometry as a versatile approach to elucidate molecular mechanisms of neurodegenerative diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jnc.12019DOI Listing
March 2013

Neonatal exposure to the cyanobacterial toxin BMAA induces changes in protein expression and neurodegeneration in adult hippocampus.

Toxicol Sci 2012 Dec 7;130(2):391-404. Epub 2012 Aug 7.

Department of Pharmaceutical Biosciences, Uppsala University, 75124 Uppsala, Sweden.

The cyanobacterial toxin β-N-methylamino-L-alanine (BMAA) has been proposed to contribute to neurodegenerative disease. We have previously reported a selective uptake of BMAA in the mouse neonatal hippocampus and that exposure during the neonatal period causes learning and memory impairments in adult rats. The aim of this study was to characterize effects in the brain of 6-month-old rats treated neonatally (postnatal days 9-10) with the glutamatergic BMAA. Protein changes were examined using the novel technique Matrix-Assisted Laser Desorption Ionization (MALDI) imaging mass spectrometry (IMS) for direct imaging of proteins in brain cryosections, and histological changes were examined using immunohistochemistry and histopathology. The results showed long-term changes including a decreased expression of proteins involved in energy metabolism and intracellular signaling in the adult hippocampus at a dose (150 mg/kg) that gave no histopathological lesions in this brain region. Developmental exposure to a higher dose (460 mg/kg) also induced changes in the expression of S100β, histones, calcium- and calmodulin-binding proteins, and guanine nucleotide-binding proteins. At this dose, severe lesions in the adult hippocampus including neuronal degeneration, cell loss, calcium deposits, and astrogliosis were evident. The data demonstrate subtle, sometimes dose-dependent, but permanent effects of a lower neonatal dose of BMAA in the adult hippocampus suggesting that BMAA could potentially disturb many processes during the development. The detection of BMAA in seafood stresses the importance of evaluating the magnitude of human exposure to this neurotoxin.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/toxsci/kfs241DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3498744PMC
December 2012

MALDI imaging mass spectrometry of neuropeptides in Parkinson's disease.

J Vis Exp 2012 Feb 14(60). Epub 2012 Feb 14.

Department of Pharmaceutical Biosciences, Uppsala University.

MALDI imaging mass spectrometry (IMS) is a powerful approach that facilitates the spatial analysis of molecular species in biological tissue samples(2) (Fig.1). A 12 μm thin tissue section is covered with a MALDI matrix, which facilitates desorption and ionization of intact peptides and proteins that can be detected with a mass analyzer, typically using a MALDI TOF/TOF mass spectrometer. Generally hundreds of peaks can be assessed in a single rat brain tissue section. In contrast to commonly used imaging techniques, this approach does not require prior knowledge of the molecules of interest and allows for unsupervised and comprehensive analysis of multiple molecular species while maintaining high molecular specificity and sensitivity(2). Here we describe a MALDI IMS based approach for elucidating region-specific distribution profiles of neuropeptides in the rat brain of an animal model Parkinson's disease (PD). PD is a common neurodegenerative disease with a prevalence of 1% for people over 65 of age(3,4). The most common symptomatic treatment is based on dopamine replacement using L-DOPA(5). However this is accompanied by severe side effects including involuntary abnormal movements, termed L-DOPA-induced dyskinesias (LID)(1,3,6). One of the most prominent molecular change in LID is an upregulation of the opioid precursor prodynorphin mRNA(7). The dynorphin peptides modulate neurotransmission in brain areas that are essentially involved in movement control(7,8). However, to date the exact opioid peptides that originate from processing of the neuropeptide precursor have not been characterized. Therefore, we utilized MALDI IMS in an animal model of experimental Parkinson's disease and L-DOPA induced dyskinesia. MALDI imaging mass spectrometry proved to be particularly advantageous with respect to neuropeptide characterization, since commonly used antibody based approaches targets known peptide sequences and previously observed post-translational modifications. By contrast MALDI IMS can unravel novel peptide processing products and thus reveal new molecular mechanisms of neuropeptide modulation of neuronal transmission. While the absolute amount of neuropeptides cannot be determined by MALDI IMS, the relative abundance of peptide ions can be delineated from the mass spectra, giving insights about changing levels in health and disease. In the examples presented here, the peak intensities of dynorphin B, alpha-neoendorphin and substance P were found to be significantly increased in the dorsolateral, but not the dorsomedial, striatum of animals with severe dyskinesia involving facial, trunk and orolingual muscles (Fig. 5). Furthermore, MALDI IMS revealed a correlation between dyskinesia severity and levels of des-tyrosine alpha-neoendorphin, representing a previously unknown mechanism of functional inactivation of dynorphins in the striatum as the removal of N-terminal tyrosine reduces the dynorphin's opioid-receptor binding capacity(9). This is the first study on neuropeptide characterization in LID using MALDI IMS and the results highlight the potential of the technique for application in all fields of biomedical research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3791/3445DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3529518PMC
February 2012

Imaging mass spectrometry reveals elevated nigral levels of dynorphin neuropeptides in L-DOPA-induced dyskinesia in rat model of Parkinson's disease.

PLoS One 2011 30;6(9):e25653. Epub 2011 Sep 30.

Department of Pharmaceutical Biosciences, Drug Safety and Toxicology, Uppsala University, Uppsala, Sweden.

L-DOPA-induced dyskinesia is a troublesome complication of L-DOPA pharmacotherapy of Parkinson's disease and has been associated with disturbed brain opioid transmission. However, so far the results of clinical and preclinical studies on the effects of opioids agonists and antagonists have been contradictory at best. Prodynorphin mRNA levels correlate well with the severity of dyskinesia in animal models of Parkinson's disease; however the identities of the actual neuroactive opioid effectors in their target basal ganglia output structures have not yet been determined. For the first time MALDI-TOF imaging mass spectrometry (IMS) was used for unbiased assessment and topographical elucidation of prodynorphin-derived peptides in the substantia nigra of a unilateral rat model of Parkinson's disease and L-DOPA induced dyskinesia. Nigral levels of dynorphin B and alpha-neoendorphin strongly correlated with the severity of dyskinesia. Even if dynorphin peptide levels were elevated in both the medial and lateral part of the substantia nigra, MALDI IMS analysis revealed that the most prominent changes were localized to the lateral part of the substantia nigra. MALDI IMS is advantageous compared with traditional molecular methods, such as radioimmunoassay, in that neither the molecular identity analyzed, nor the specific localization needs to be predetermined. Indeed, MALDI IMS revealed that the bioconverted metabolite leu-enkephalin-arg also correlated positively with severity of dyskinesia. Multiplexing DynB and leu-enkephalin-arg ion images revealed small (0.25 by 0.5 mm) nigral subregions with complementing ion intensities, indicating localized peptide release followed by bioconversion. The nigral dynorphins associated with L-DOPA-induced dyskinesia were not those with high affinity to kappa opioid receptors, but consisted of shorter peptides, mainly dynorphin B and alpha-neoendorphin that are known to bind and activate mu and delta opioid receptors. This suggests that mu and/or delta subtype-selective opioid receptor antagonists may be clinically relevant for reducing L-DOPA-induced dyskinesia in Parkinson's disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0025653PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3184165PMC
March 2012

L-DOPA-induced dyskinesia is associated with regional increase of striatal dynorphin peptides as elucidated by imaging mass spectrometry.

Mol Cell Proteomics 2011 Oct 6;10(10):M111.009308. Epub 2011 Jul 6.

Department of Pharmaceutical Biosciences, Drug Safety and Toxicology, Uppsala University, Uppsala, Sweden.

Opioid peptides are involved in various pathophysiological processes, including algesia, epilepsy, and drug dependence. A strong association between L-DOPA-induced dyskinesia (LID) and elevated prodynorphin mRNA levels has been established in both patients and in animal models of Parkinson's disease, but to date the endogenous prodynorphin peptide products have not been determined. Here, matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) was used for characterization, localization, and relative quantification of striatal neuropeptides in a rat model of LID in Parkinson's disease. MALDI IMS has the unique advantage of high sensitivity and high molecular specificity, allowing comprehensive detection of multiple molecular species in a single tissue section. Indeed, several dynorphins and enkephalins could be detected in the present study, including dynorphin A(1-8), dynorphin B, α-neoendorphin, MetEnkRF, MetEnkRGL, PEnk (198-209, 219-229). IMS analysis revealed elevated levels of dynorphin B, α-neoendorphin, substance P, and PEnk (220-229) in the dorsolateral striatum of high-dyskinetic animals compared with low-dyskinetic and lesion-only control rats. Furthermore, the peak-intensities of the prodynorphin derived peptides, dynorphin B and α-neoendorphin, were strongly and positively correlated with LID severity. Interestingly, these LID associated dynorphin peptides are not those with high affinity to κ opioid receptors, but are known to bind and activate also μ- and Δ-opioid receptors. In addition, the peak intensities of a novel endogenous metabolite of α-neoendorphin lacking the N-terminal tyrosine correlated positively with dyskinesia severity. MALDI IMS of striatal sections from Pdyn knockout mice verified the identity of fully processed dynorphin peptides and the presence of endogenous des-tyrosine α-neoendorphin. Des-tyrosine dynorphins display reduced opioid receptor binding and this points to possible novel nonopioid receptor mediated changes in the striatum of dyskinetic rats. Because des-tyrosine dynorphins can only be detected by mass spectrometry, as no antibodies are available, these findings highlight the importance of MALDI IMS analysis for the study of molecular dynamics in neurological diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/mcp.M111.009308DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3205869PMC
October 2011

MALDI mass spectrometry based molecular phenotyping of CNS glial cells for prediction in mammalian brain tissue.

Anal Bioanal Chem 2011 Jul 7;401(1):135-47. Epub 2011 May 7.

Department of Pharmaceutical Bioscience, Drug Safety and Toxicology, Uppsala University, Uppsala, Sweden.

The development of powerful analytical techniques for specific molecular characterization of neural cell types is of central relevance in neuroscience research for elucidating cellular functions in the central nervous system (CNS). This study examines the use of differential protein expression profiling of mammalian neural cells using direct analysis by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). MALDI-MS analysis is rapid, sensitive, robust, and specific for large biomolecules in complex matrices. Here, we describe a newly developed and straightforward methodology for direct characterization of rodent CNS glial cells using MALDI-MS-based intact cell mass spectrometry (ICMS). This molecular phenotyping approach enables monitoring of cell growth stages, (stem) cell differentiation, as well as probing cellular responses towards different stimulations. Glial cells were separated into pure astroglial, microglial, and oligodendroglial cell cultures. The intact cell suspensions were then analyzed directly by MALDI-TOF-MS, resulting in characteristic mass spectra profiles that discriminated glial cell types using principal component analysis. Complementary proteomic experiments revealed the identity of these signature proteins that were predominantly expressed in the different glial cell types, including histone H4 for oligodendrocytes and S100-A10 for astrocytes. MALDI imaging MS was performed, and signature masses were employed as molecular tracers for prediction of oligodendroglial and astroglial localization in brain tissue. The different cell type specific protein distributions in tissue were validated using immunohistochemistry. ICMS of intact neuroglia is a simple and straightforward approach for characterization and discrimination of different cell types with molecular specificity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-011-5043-yDOI Listing
July 2011

Fine mapping the spatial distribution and concentration of unlabeled drugs within tissue micro-compartments using imaging mass spectrometry.

PLoS One 2010 Jul 14;5(7):e11411. Epub 2010 Jul 14.

Medical Mass Spectrometry, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.

Readouts that define the physiological distributions of drugs in tissues are an unmet challenge and at best imprecise, but are needed in order to understand both the pharmacokinetic and pharmacodynamic properties associated with efficacy. Here we demonstrate that it is feasible to follow the in vivo transport of unlabeled drugs within specific organ and tissue compartments on a platform that applies MALDI imaging mass spectrometry to tissue sections characterized with high definition histology. We have tracked and quantified the distribution of an inhaled reference compound, tiotropium, within the lungs of dosed rats, using systematic point by point MS and MS/MS sampling at 200 microm intervals. By comparing drug ion distribution patterns in adjacent tissue sections, we observed that within 15 min following exposure, tiotropium parent MS ions (mass-to-charge; m/z 392.1) and fragmented daughter MS/MS ions (m/z 170.1 and 152.1) were dispersed in a concentration gradient (80 fmol-5 pmol) away from the central airways into the lung parenchyma and pleura. These drug levels agreed well with amounts detected in lung compartments by chemical extraction. Moreover, the simultaneous global definition of molecular ion signatures localized within 2-D tissue space provides accurate assignment of ion identities within histological landmarks, providing context to dynamic biological processes occurring at sites of drug presence. Our results highlight an important emerging technology allowing specific high resolution identification of unlabeled drugs at sites of in vivo uptake and retention.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0011411PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904372PMC
July 2010

Alzheimer's disease: No effect of the CDK5 gene on CSF biomarkers, neuropathology or disease risk.

Mol Med Rep 2009 Nov-Dec;2(6):989-92

Department of Clinical Chemistry and Transfusion Medicine, Molecular Biology, The Sahlgrenska Academy at Göteborg University, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden.

Cyclin-dependent kinase 5 (cdk5) has been identified as one of the kinases that phosphorylates tau at several Alzheimer's disease (AD)-associated sites. Cdk5 is predominantly expressed in neurons, and has higher activity in AD brains than in non-demented brains. To investigate the effect of the CDK5 gene on AD, we analyzed an SNP of the CDK5 gene (rs2069456) in 347 patients with AD and in 157 controls. CDK5 genetic data was investigated in subgroups in relation to biochemical and neuropathological markers for AD. We found no significant differences in genotype or allele distributions between AD patients and controls. None of the CDK5 gene variants influenced biomarkers for AD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3892/mmr_00000203DOI Listing
October 2012

Association of nAChR gene haplotypes with heavy alcohol use and body mass.

Brain Res 2009 Dec 19;1305 Suppl:S72-9. Epub 2009 Aug 19.

Institute of Neuroscience and Physiology, Department of Pharmacology, University of Gothenburg, Sweden.

Co-occurring alcohol and nicotine dependence is common, as is alcohol use disorder and overeating. However, major risk genes for these disorders need to be identified. Certain subtypes of the nicotinic acetylcholine receptors in the ventral tegmental area (a reward node) have preclinically been shown to be important for alcohol reward. Therefore the aim was to investigate nicotine receptor subunit genes in a haplotype study of alcohol use. This study includes a Spanish population (n=417) of three groups based on their alcohol consumption; abstainers (n=142), moderate (<280 g/week, n=111) and heavy drinkers (>280 g/week, n=164). 20 tag SNPs in five nicotine receptor subunit genes (CHRNA3, 4, and 6; CHRNB2 and 3) were genotyped and analysed for single marker and haplotype associations. Two haplotypes of the CHRNA6 (CCCC and TCGA) were associated with heavy alcohol consumption (p=0.004 and p=0.035 respectively) and with increased alcohol intake (p=0.004) for the CCCC haplotype compared to non-carriers of these haplotypes. Moreover, one haplotype of the CHRNA4 (GGTG) was associated with increased body weight as compared to non-carriers of this haplotype, especially in the heavy consumers of alcohol (p=0.004).The present findings are the first to disclose a haplotype association between the CHRNA6 gene and heavy alcohol use as well as an association of the CHRNA4 gene with increased body mass in heavy consumers of alcohol. Taken together with previous preclinical data, this targets the nicotinic acetylcholine receptors for development of novel treatment strategies of addictive behaviours, and, more specifically, of a subgroup of individuals with co-morbid alcohol use disorder and overeating.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.brainres.2009.08.026DOI Listing
December 2009

Heat stabilization of the tissue proteome: a new technology for improved proteomics.

J Proteome Res 2009 Feb;8(2):974-81

Denator AB, Uppsala Science Park, Dag Hammarskjölds väg 32a, 751 83, Uppsala, Sweden.

After tissue or body fluid sampling, proteases and other protein-modifying enzymes can rapidly change composition of the proteome. As a direct consequence, analytical results will reflect a mix of in vivo proteome and ex vivo degradation products. Vital information about the presampling state may be destroyed or distorted, leading to variation between samples and incorrect conclusions. Sample stabilization and standardization of sample handling can reduce or eliminate this problem. Here, a novel tissue stabilization system which utilizes a combination of heat and pressure under vacuum was used to stop degradation in mouse brain tissue immediately after sampling. It was found by biochemical assays that enzymatic activity was reduced to background levels in stabilized samples. Western blot analysis confirmed that post-translational phosphorylations of analyzed proteins were stable and conserved for up to 2 h at room temperature and that peptide extracts were devoid of abundant protein degradation fragments. The combination of reduced complexity and proteolytic inactivation enabled mass spectrometric identification of several neuropeptides and endogenous peptides including modified species at higher levels compared to nonstabilized samples. The tissue stabilizing system ensures reproducible and rapid inactivation of enzymes. Therefore, the system provides a powerful improvement to proteomics by greatly reducing the complexity and dynamic range of the proteome in tissue samples and enables enhanced possibilities for discovery and analysis of clinically relevant protein/peptide biomarkers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/pr8006446DOI Listing
February 2009

Urinary detection times and metabolite/parent compound ratios after a single dose of buprenorphine.

J Anal Toxicol 2008 Oct;32(8):586-93

National Board of Forensic Medicine, Department of Forensic Genetics and Forensic Toxicology, Linkoping, Sweden.

The objective was to estimate the detection times and metabolite/parent compound ratios in urine after a single dose of buprenorphine. Eighteen healthy volunteers received a single dose of 0.4 mg buprenorphine sublingually. Urine samples were collected prior to dosing and at 2, 4, 6, 8 12, 24, 48, 72, and 96 h post-dose. The samples were screened using cloned enzyme donor immunoassay (CEDIA) reagent and quantitation was performed with liquid chromatography-tandem mass spectrometry (LC-MS-MS) with a cut-off of 0.5 ng/mL for buprenorphine and norbuprenorphine. The mean time of continuous positive results was 9 h (range 4 to 24 h) with CEDIA, whereas for an LC-MS-MS method it was 76 h (range 23-96 h) for buprenorphine, and for norbuprenorphine all samples were positive at 96 h. Some subjects had positive CEDIA results after a negative sample, owing to differences in creatinine concentration. The time when the ratio norbuprenorphine/buprenorphine exceeded 1 was estimated at 7 h. The metabolite/parent ratio may be used to estimate the time of intake even though the individual ratios showed an increased variation the more distant the collection time. We believe that using this ratio, rather than the actual concentrations, it is possible to compensate for urine dilution and different doses, and to improve interpretation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/jat/32.8.586DOI Listing
October 2008

Elevated cerebrospinal fluid BACE1 activity in incipient Alzheimer disease.

Arch Neurol 2008 Aug;65(8):1102-7

Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at Göteborg University, Mölndal, Sweden.

Background: We used a sensitive and specific beta-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) assay to determine the relationship between BACE1 activity in cerebrospinal fluid (CSF) and markers of APP metabolism and axonal degeneration in early and late stages of Alzheimer disease (AD).

Objective: To assess CSF BACE1 activity in AD.

Design: Case-control and longitudinal follow-up study.

Setting: Specialized memory clinic. Patients Eighty-seven subjects with AD, 33 cognitively normal control subjects, and 113 subjects with mild cognitive impairment (MCI), who were followed up for 3 to 6 years.

Main Outcome Measures: Cerebrospinal fluid BACE1 activity in relation to diagnosis and CSF levels of secreted APP and amyloid beta protein (Abeta) isoforms and the axonal degeneration marker total tau.

Results: Subjects with AD had higher CSF BACE1 activity (median, 30 pM [range, 11-96 pM]) than controls (median, 23 pM [range, 8-43 pM]) (P =.02). Subjects with MCI who progressed to AD during the follow-up period had higher baseline BACE1 activity (median, 35 pM [range, 18-71 pM]) than subjects with MCI who remained stable (median, 29 pM [range, 14-83 pM]) (P < .001) and subjects with MCI who developed other forms of dementia (median, 20 pM [range, 10-56 pM]) (P <.001). BACE1 activity correlated positively with CSF levels of secreted APP isoforms and Abeta(40) in the AD and control groups and in all MCI subgroups (P < .05) except the MCI subgroup that developed AD. Strong positive correlations were found between CSF BACE1 activity and total tau levels in all MCI subgroups (r >or= 0.57, P
Conclusion: Elevated BACE1 activity may contribute to the amyloidogenic process in sporadic AD and is associated with the intensity of axonal degeneration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1001/archneur.65.8.1102DOI Listing
August 2008