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Ek, Pia
Publications (10 of 20) Show all publications
Adolfsson, P., Ek, P. & Umb-Carlsson, Õ. (2019). Dietitians’ challenges when consulting to adults with intellectual disabilities. Tizard Learning Disability Review, 24(4), 153-162
Open this publication in new window or tab >>Dietitians’ challenges when consulting to adults with intellectual disabilities
2019 (English)In: Tizard Learning Disability Review, ISSN 1359-5474, E-ISSN 2042-8782, ISSN ISSN 1359-5474,, Vol. 24, no 4, p. 153-162Article in journal (Refereed) Published
Abstract [en]

Purpose: The purpose of this paper is to investigate registered dietitians' (RDs) experiences in consulting to adults with intellectual disabilities (ID) in Sweden.

Design/methodology/approach: A descriptive study using a study-specific web-based questionnaire was administered, comprising both multiple-choice questions with a space for comments and open-ended questions. The open-ended answers and comments from 53 respondents were analysed with systematic text condensation.

Findings: Four categories were identified: RDs' experiences from the first meeting; explanations for late initial contact; the actions taken by RDs; and necessary measures for more sustainable nutrition care. Ten sub-categories described the challenges that RDs experience in more detail.

Practical implications: It is necessary to provide adults with ID and their supporting staff with individually tailored nutritional information. Individuals with ID must be actively involved in lifestyle changes that affect their everyday life. The RD must be included in the interdisciplinary team supporting adults with ID. If a new practice is to be implemented, it should be compatible with the existing values of adults with ID and their staff and must be feasible to implement in the everyday life of the individual.

Originality/value: This paper identified several barriers that should be overcome in relation to the preparation of RDs for consultation with adults with ID about nutritional health issues. A systematic structure, knowledge about nutrition and knowledge about adults with ID and their living situations are needed. An assessment instrument may meet health promotion needs and facilitate longitudinal follow-ups of nutritional problems.

National Category
Nutrition and Dietetics
Identifiers
urn:nbn:se:uu:diva-395125 (URN)10.1108/TLDR-11-2018-0033 (DOI)000494033800001 ()
Available from: 2019-10-13 Created: 2019-10-13 Last updated: 2019-12-16Bibliographically approved
Ek, P., Ek, B. & Zetterqvist, Ö. (2015). Phosphohistidine phosphatase 1 (PHPT1) also dephosphorylates phospholysine of chemically phosphorylated histone H1 and polylysine. Upsala Journal of Medical Sciences, 120(1), 20-27
Open this publication in new window or tab >>Phosphohistidine phosphatase 1 (PHPT1) also dephosphorylates phospholysine of chemically phosphorylated histone H1 and polylysine
2015 (English)In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 120, no 1, p. 20-27Article in journal (Refereed) Published
Abstract [en]

Background. Phosphohistidine phosphatase 1 (PHPT1), also named protein histidine phosphatase (PHP), is a eukaryotic enzyme dephosphorylating proteins and peptides that are phosphorylated on a histidine residue. A preliminary finding that histone H1, which lacks histidine, was phosphorylated by phosphoramidate and dephosphorylated by PHPT1 prompted the present investigation. Methods. Histone H1 and polylysine were phosphorylated at a low concentration (3.9 mM) of phosphoramidate. Their dephosphorylation by recombinant human PHPT1 was investigated by using a DEAE-Sepharose spin column technique earlier developed by us for studies on basic phosphoproteins and phosphopeptides. Determination of protein-bound, acid-labile phosphate was performed by a malachite green method. Mass spectrometry (MS) was used to investigate the occurrence of N-epsilon-phospholysine residues in a phosphorylated histone H 1.2 preparation, and to measure the activity of PHPT1 against free N-omega-phosphoarginine. Results. Histone H1.2, which lacks histidine, was phosphorylated by phosphoramidate on several lysine residues, as shown by MS. PHPT1 was shown to dephosphorylate phosphohistone H1 at a rate similar to that previously described for the dephosphorylation of phosphohistidine-containing peptides. In addition, phosphopolylysine was an equally good substrate for PHPT1. However, no dephosphorylation of free phosphoarginine by PHPT1 could be detected. Conclusion. The finding that PHPT1 can dephosphorylate phospholysine in chemically phosphorylated histone H1 and polylysine demonstrates a broader specificity for this enzyme than known so far.

Keywords
Histone H1, phosphohistidine phosphatase, phospholysine, phospholysine phosphatase, PHP, PHPT1, protein histidine phosphatase
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:uu:diva-251517 (URN)10.3109/03009734.2014.996720 (DOI)000350984700003 ()25574816 (PubMedID)
Available from: 2015-04-23 Created: 2015-04-20 Last updated: 2017-12-04Bibliographically approved
Inturi, R., Wäneskog, M., Vlachakis, D., Ali, Y., Ek, P., Punga, T. & Bjerling, P. (2014). A splice variant of the human phosphohistidine phosphatase 1 (PHPT1) is degraded by the proteasome. International Journal of Biochemistry and Cell Biology, 57, 69-75
Open this publication in new window or tab >>A splice variant of the human phosphohistidine phosphatase 1 (PHPT1) is degraded by the proteasome
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2014 (English)In: International Journal of Biochemistry and Cell Biology, ISSN 1357-2725, E-ISSN 1878-5875, Vol. 57, p. 69-75Article in journal (Refereed) Published
Abstract [en]

Regulation of protein activity by phosphorylation is central in many cellular processes. Phosphorylation of serine, threonine and tyrosine residues is well documented and studied. In addition, other amino acids, like histidine can be phosphorylated, but neither the mechanism nor the function of this modification is well understood. Nevertheless, there is a 14 kDa enzyme with phosphohistidine phosphatase activity, named PHPT1, found in most animals, but not in bacteria, plant or fungi. There are a few splice variant transcripts formed from the human PHPT1 locus and some of them are predicted to form variant proteins, but studies of these proteins are lacking. In order to get insight into the possible function of the variant transcripts encoded at the PHPT1 locus, ectopic expression of PHPT1 transcript variant 6, predicted to be degraded by the non-sense mediated mRNA decay pathway, in HeLa cells was undertaken. In HeLa cells the splice variant protein was degraded by the proteasome, unlike the wild type protein. Using an in silico modeling approach the variant C-terminal end of the proteins were predicted to form different secondary structures that might explain the different properties of the two proteins. The specific degradation of the PHPT1 splice variant indicates that at least for the PHPT1 protein, the quality control and the self-guarding of the cellular system works at two levels, first at the RNA level, aberrant transcripts are degraded by the non-sense mediated mRNA decay pathway, and the small amount of proteins that are formed will be degraded by the proteasome.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Phosphohistidine phosphatase, PHPT1, Proteasome, Splice variant, Nonsense-mediated decay
National Category
Biological Sciences
Research subject
Biology with specialization in Molecular Cell Biology
Identifiers
urn:nbn:se:uu:diva-235728 (URN)10.1016/j.biocel.2014.10.009 (DOI)000347662300009 ()25450458 (PubMedID)
Funder
Swedish Research Council, 6212011-4688Swedish Research Council, K2012-99X-21959-01-3Swedish Cancer Society, 13 0410
Available from: 2014-11-07 Created: 2014-11-07 Last updated: 2019-05-13Bibliographically approved
Tavoosidana, G., Ronquist, G., Darmanis, S., Yan, J., Carlsson, L., Wu, D., . . . Kamali-Moghaddam, M. (2011). Multiple recognition assay reveals prostasomes as promising plasma biomarkers for prostate cancer. Proceedings of the National Academy of Sciences of the United States of America, 108(21), 8809-8814
Open this publication in new window or tab >>Multiple recognition assay reveals prostasomes as promising plasma biomarkers for prostate cancer
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2011 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 21, p. 8809-8814Article in journal (Refereed) Published
Abstract [en]

Prostasomes are microvesicles (mean diameter, 150 nm) that are produced and secreted by normal and malignant prostate acinar cells. It has been hypothesized that invasive growth of malignant prostate cells may cause these microvesicles, normally released into seminal fluid, to appear in interstitial space and therewith into peripheral circulation. The suitability of prostasomes as blood biomarkers in patients with prostate cancer was tested by using an expanded variant of the proximity ligation assay (PLA). We developed an extremely sensitive and specific assay (4PLA) for detection of complex target structures such as microvesicles in which the target is first captured via an immobilized antibody and subsequently detected by using four other antibodies with attached DNA strands. The requirement for coincident binding by five antibodies to generate an amplifiable reporter results in both increased specificity and sensitivity. The assay successfully detected significantly elevated levels of prostasomes in blood samples from patients with prostate cancer before radical prostatectomy, compared with controls and men with benign biopsy results. The medians for prostasome levels in blood plasma of patients with prostate cancer were 2.5 to sevenfold higher compared with control samples in two independent studies, and the assay also distinguished patients with high and medium prostatectomy Gleason scores (8/9 and 7, respectively) from those with low score (<= 6), thus reflecting disease aggressiveness. This approach that enables detection of prostasomes in peripheral blood may be useful for early diagnosis and assessment of prognosis in organ-confined prostate cancer.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-144092 (URN)10.1073/pnas.1019330108 (DOI)000290908000058 ()21555566 (PubMedID)
Funder
EU, FP7, Seventh Framework ProgrammeKnut and Alice Wallenberg FoundationSwedish Research Council
Available from: 2011-01-27 Created: 2011-01-27 Last updated: 2017-12-11Bibliographically approved
Zhang, X.-Q., Sundh, U. B., Jansson, L., Zetterqvist, Ö. & Ek, P. (2009). Immunohistochemical localization of phosphohistidine phosphatase PHPT1 in mouse and human tissues. Upsala Journal of Medical Sciences, 114(2), 65-72
Open this publication in new window or tab >>Immunohistochemical localization of phosphohistidine phosphatase PHPT1 in mouse and human tissues
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2009 (English)In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 114, no 2, p. 65-72Article in journal (Refereed) Published
Abstract [en]

Protein histidine phosphorylation accounts for about 6% of the total protein phosphorylation in eukaryotic cells; still details concerning histidine phosphorylation and dephosphorylation are limited. A mammalian 14-kDa phosphohistidine phosphatase, also denominated PHPT1, was found 6 years ago that provided a new tool in the study of phosphohistidine phosphorylation. The localization of PHPT1 mRNA by Northern blot analysis revealed high expression in heart and skeletal muscle. The main object of the present study was to determine the PHPT1 expression on protein level in mouse tissues in order to get further information on the physiological role of the enzyme. Tissue samples from adult mice and 14.5-day-old mouse embryos were processed for immunostaining using a PHPT1-specific polyclonal antibody. The same antibody was also provided to the Swedish human protein atlas project (HPR) (http://www.proteinatlas.org/index.php). The results from both studies were essentially consistent with the previously reported expression of mRNA of a few human tissues. In addition, several other tissues, including testis, displayed a high protein expression. A salient result of the present investigation was the ubiquitous expression of the PHPT1 protein and its high expression in continuously dividing epithelial cells.

Keywords
Phosphohistidine phosphatase, PHPT1, PHP, phosphohistidine, dephosphorylation, HPR-project
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-119851 (URN)10.1080/03009730802642337 (DOI)000265454800001 ()19396692 (PubMedID)
Available from: 2010-03-02 Created: 2010-03-02 Last updated: 2017-12-12Bibliographically approved
Loog, M., Oskolkov, N., O'Farrell, F., Ek, P. & Järv, J. (2005). Comparison of cAMP-dependent protein kinase substrate specificity in reaction with proteins and synthetic peptides.. Biochim Biophys Acta, 1747(2), 261-6
Open this publication in new window or tab >>Comparison of cAMP-dependent protein kinase substrate specificity in reaction with proteins and synthetic peptides.
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2005 (English)In: Biochim Biophys Acta, ISSN 0006-3002, Vol. 1747, no 2, p. 261-6Article in journal (Refereed) Published
Keywords
Catalysis, Comparative Study, Cyclic AMP-Dependent Protein Kinases/*metabolism, Electrophoresis; Polyacrylamide Gel, Mutagenesis; Site-Directed, Mutation, Peptides/chemical synthesis/*metabolism, Phosphorylation, Pyruvate Kinase/metabolism, Research Support; Non-U.S. Gov't, Substrate Specificity
Identifiers
urn:nbn:se:uu:diva-80303 (URN)15698961 (PubMedID)
Available from: 2006-05-05 Created: 2006-05-05 Last updated: 2011-01-11
Ma, R., Kanders, E., Sundh, U. B., Geng, M., Ek, P., Zetterqvist, Ö. & Li, J.-P. (2005). Mutational study of human phosphohistidine phosphatase: effect on enzymatic activity.. Biochem Biophys Res Commun, 337(3), 887-91
Open this publication in new window or tab >>Mutational study of human phosphohistidine phosphatase: effect on enzymatic activity.
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2005 (English)In: Biochem Biophys Res Commun, ISSN 0006-291X, Vol. 337, no 3, p. 887-91Article in journal (Refereed) Published
Keywords
Amino Acid Sequence, Amino Acid Substitution, Binding Sites, Enzyme Activation, Evolution; Molecular, Humans, Molecular Sequence Data, Mutagenesis; Site-Directed, Mutation, Phosphoprotein Phosphatase/analysis/*chemistry/genetics/*metabolism, Protein Binding, Recombinant Proteins/analysis/chemistry/metabolism, Research Support; Non-U.S. Gov't, Sequence Homology; Amino Acid, Structure-Activity Relationship, Substrate Specificity
Identifiers
urn:nbn:se:uu:diva-80308 (URN)16219293 (PubMedID)
Available from: 2006-05-05 Created: 2006-05-05 Last updated: 2012-05-30
Loog, M., Ek, B., Oskolkov, N., Narvanen, A., Järv, J. & Ek, P. (2005). Screening for the optimal specificity profile of protein kinase C using electrospray mass-spectrometry.. J Biomol Screen, 10(4), 320-8
Open this publication in new window or tab >>Screening for the optimal specificity profile of protein kinase C using electrospray mass-spectrometry.
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2005 (English)In: J Biomol Screen, ISSN 1087-0571, Vol. 10, no 4, p. 320-8Article in journal (Refereed) Published
Keywords
Amino Acid Sequence, Enzyme Inhibitors/pharmacology, Kinetics, Molecular Sequence Data, Peptide Library, Phosphorylation, Protein Kinase C/antagonists & inhibitors/chemistry/*metabolism, Research Support; Non-U.S. Gov't, Spectrometry; Mass; Electrospray Ionization/*methods, Substrate Specificity
Identifiers
urn:nbn:se:uu:diva-80302 (URN)15964933 (PubMedID)
Available from: 2006-05-05 Created: 2006-05-05 Last updated: 2011-01-11
Ek, P., Malm, J., Lilja, H., Carlsson, L. & Ronquist, G. (2002). Exogenous protein kinases A and C, but not endogenous prostasome-associated protein kinase, phosphorylate semenogelins I and II from human semen. Journal of Andrology, 23(6), 806-814
Open this publication in new window or tab >>Exogenous protein kinases A and C, but not endogenous prostasome-associated protein kinase, phosphorylate semenogelins I and II from human semen
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2002 (English)In: Journal of Andrology, ISSN 0196-3635, E-ISSN 1939-4640, Vol. 23, no 6, p. 806-814Article in journal (Refereed) Published
Abstract [en]

Semenogelins I and II are the quantitatively dominating proteinsin humansemen. They comprise the major part of the sperm-entrappinggel formed atejaculation, which subsequently liquefies dueto proteolysis of thegel-forming proteins by prostate-specificantigen (PSA). The mechanism behindgel formation and its physiologicalsignificance is not known. We have studiedphosphorylation anddephosphorylation of human semenogelins. Both werephosphorylatedby protein kinases A and C (PKA and PKC, respectively) at arateabout 5 times less than that of histone. For PKA, incorporated(32P)phosphateinto semenogelin approached a maximum above 1mol/mol. Correspondingvalues for phosphorylation of the semenogelins with PKCweregreater than 10. There was no change in the sensitivity ofphosphosemenogelinsto proteolysis by PSA. Serine (PKA) and serine andthreonine(PKC) were the phosphate-accepting amino acid residues, andallincorporated (32P)phosphate could be removed from the semenogelinswithhuman acid phosphatase. Nil or very little phosphate could bedetected inpurified semenogelins isolated from seminal plasma.In vivo, about half theprotein kinase activity in seminal plasmawas bound to prostasomes. PKA butnot PKC purified from prostasomescould phosphorylate specific substrates, butthey could phosphorylateeither of the semenogelins.

Keywords
Acid phosphatase, histone, prostate-specific antigen, vasectomy
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-65798 (URN)
Available from: 2008-10-17 Created: 2008-10-17 Last updated: 2017-11-28Bibliographically approved
Ek, P., Zetterqvist, Ö., Li, J.-P., Ek, B., Pettersson, G. & Gong, F. (2002). Identification and characterization of a mammalian 14-kDa phosphohistidine phosphatase. European Journal of Biochemistry, 269, 5016-5023
Open this publication in new window or tab >>Identification and characterization of a mammalian 14-kDa phosphohistidine phosphatase
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2002 (English)In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 269, p. 5016-5023Article in journal (Refereed) Published
Abstract [en]

Protein histidine phosphorylation in eukaryotes has beensparsely studied compared to protein serine/threonine andtyrosine phosphorylation. In an attempt to rectify this byprobing porcine liver cytosol with the phosphohistidinecontainingpeptide succinyl-Ala-His(P)-Pro-Phe-p-nitroanilide(phosphopeptide I), we observed a phosphataseactivity that was insensitive towards okadaic acid andEDTA. This suggested the existence of a phosphohistidinephosphatase different from protein phosphatase 1, 2Aand 2C. A 1000-fold purification to apparent homogeneitygave a 14-kDa phosphatase with a specific activity of 3lmolÆmin)1Æmg)1 at pH 7.5 with 7 lM phosphopeptide Ias substrate. Partial amino-acid sequence determination ofthe purified porcine enzyme by MS revealed similaritywith a human sequence representing a human chromosome9 gene of hitherto unknown function. Molecularcloning from a human embryonic kidney cell cDNAlibraryfollowed by expression and purification, yielded aprotein with a molecular mass of 13 700 Da, and anEDTA-insensitive phosphohistidine phosphatase activityof 9 lmolÆmin)1Æmg)1 towards phosphopeptide I. Nodetectable activity was obtained towards a set of phosphoserine-,phosphothreonine-, and phosphotyrosine peptides.Northern blot analysis indicated that the humanphosphohistidine phosphatase mRNA was present preferentiallyin heart and skeletal muscle. These resultsprovide a new tool for studying eukaryotic histidinephosphorylation/dephosphorylation.

Keywords
dephosphorylation, N-phosphorylation, phosphoamidase, phosphopeptide, protein histidine phosphatase
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Research subject
Biochemistry
Identifiers
urn:nbn:se:uu:diva-145972 (URN)10.1046/j.1432-1033.2002.03206.x (DOI)000178608400012 ()
Available from: 2011-02-14 Created: 2011-02-14 Last updated: 2017-12-11Bibliographically approved
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