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Rolf Ekman

Publications and source records attributed to Rolf Ekman.

12 recordsLinked to original sources
PubMed2005

Proteomics and peptidomics in neuroscience. Experience of capabilities and limitations in a neurochemical laboratory.

The increasing use of proteomics has created a basis for new strategies to develop methodologies for rapid identification of protein patterns in living organisms. It has also become evident that proteomics has other potential applications than protein and peptide identification, e.g. protein characterization, with the aim of revealing their structure, function(s) and interactions of proteins. In comparative proteomics studies, the protein expression of a certain biological system is compared with another system or the same system under perturbed conditions. Global identification of proteins in neuroscience is extremely complex, owing to the limited availability of biological material and very low concentrations of the molecules. Moreover, in addition to proteins, there are number of peptides that must also be considered in global studies on the central nervous system. In this overview, we focus on and discuss problems related to the different sources of biological material and sample handling, which are part of all preparatory and analytical steps. Straightforward protocols are desirable to avoid excessive purification steps, since loss of material at each step is inevitable. We would like to merge the two worlds of proteomics/peptidomics and neuroscience, and finally we consider different practical and technical aspects, illustrated with examples from our laboratory.

Animals↗
PubMed2004

Cerebrospinal neuropeptide Y and substance P in suicide attempters during long-term antidepressant treatment.

This study describes cerebrospinal fluid (CSF), neuropeptide Y (NPY) and substance P (SP) in patients with a recent suicide attempt and during antidepressant treatment. Seven out of 13 patients received antidepressants. The patients were examined on three separate occasions, i.e. at pre-treatment, followed by every 3 or 4 months. Antidepressant treatment seemed to affect the levels of CSF NPY, which decreased significantly between the second and last lumbar puncture despite no significant changes of clinical scores. When the whole group was taken into consideration, both CSF NPY and SP decreased significantly. At pre-treatment, Brief Scale of Anxiety scores were significantly and negatively correlated to CSF SP and tended to be negatively correlated to CSF NPY. There were also significant positive correlations between CSF NPY and SP during the entire study in the whole group, possibly reflecting an inter-relationship between these neuropeptides.

Adult↗
PubMed2003

Proteome analysis of conditioned medium from cultured adult hippocampal progenitors.

It is known that proliferation and survival of neural stem/progenitor cells in vitro not only depend on exogenous factors, but also on autocrine factors secreted into the conditioned medium. It is also well known that the identification of bioactive proteins secreted into the conditioned medium poses a substantial challenge. Recently, neural stem/progenitor cells were shown to secrete a survival factor, cystatin C, into the conditioned medium. Here, we demonstrate an approach to identify other low molecular weight proteins in conditioned medium from cultured adult rat hippocampal progenitor cells. A combination of preparative two-dimensional gel electrophoresis (2-DE) and mass spectrometry was utilized in the analysis. We were able to identify a number of proteins, which include Rho-guanine nucleotide dissociation inhibitor 1, phosphatidylethanolamine binding protein (PEBP), also termed Raf-1 kinase interacting protein, polyubiquitin, immunophilin FK506 binding protein 12 (FKBP12) and cystatin C. The presence of PEBP and FKBP12 in conditioned medium was confirmed immunologically. All nestin-positive progenitor cells showed immunoreactivity for antibodies against PEBP and FKBP12. To our knowledge we are the first to use this preparative proteomic approach to search for stem cell factors in conditioned medium. The method could be used to identify novel bioactive proteins secreted by stem/progenitor cells in vitro. Identification of bioactive proteins in vitro is of potential importance for the understanding of the regulatory mechanisms of the cells in vivo.

Aging↗
PubMed2003

Mu- and delta-opioid receptor antagonists decrease proliferation and increase neurogenesis in cultures of rat adult hippocampal progenitors.

Opioids have previously been shown to affect proliferation and differentiation in various neural cell types. In the present study, cultured rat adult hippocampal progenitors (AHPs) were shown to release beta-endorphin. Membrane preparations of AHPs were found to bind [125I]beta-endorphin, and immunoreactivity for mu- and delta-opioid receptors (MORs and DORs), but not for kappa-opioid receptors (KORs), was found on cells in culture. Both DNA content and [3H]thymidine incorporation were reduced after a 48-h incubation with 100 microM naloxone, 10 micro m naltrindole or 10 microM beta-funaltrexamine, but not nor-binaltorphimine, suggesting proliferative actions of endogenous opioids against MORs and DORs on AHPs. Furthermore, analysis of gene and protein expression after incubation with MOR and DOR antagonists for 48 h using RT-PCR and Western blotting suggested decreased signalling through the mitogen-activated protein kinase (MAPK) pathway and lowered levels of genes and proteins that are important in cell cycling. Cultures were incubated with naloxone (10 or 100 microM) for 10 days to study the effects on differentiation. This resulted in an approximately threefold increase in neurogenesis, a threefold decrease in astrogliogenesis and a 50% decrease in oligodendrogenesis. In conclusion, this study suggests that reduced signalling through MORs and DORs decreases proliferation in rat AHPs, increases the number of in vitro-generated neurons and reduces the number of astrocytes and oligodendrocytes in culture.

Animals↗
PubMed2002

Suicide-attempters having immunoglobulin G with affinity for dopamine in cerebrospinal fluid.

Altered immunological functions and changes in the monoaminergic neurotransmitter systems are two important observations made previously in the study of possible etiological and pathophysiological factors for psychiatric disorders. In search of tentative autoimmune mechanisms involved in these disorders we studied the presence of immunoglobulin G (DA-IgG) with affinity for the monoamine dopamine (DA) in cerebrospinal fluid (CSF) using ELISA. In CSF from 49 suicide attempters the titer of DA-IgG was significantly higher (P<0.001) than in CSF obtained from control subjects undergoing neurological investigation. The results in the present study indicate that an autoimmune mechanism may be involved in the dopaminergic neurotransmitter system and may be of pathophysiological importance in psychiatric disorders connected to an attempt of suicide.

Adult↗
PubMed1992

Dynamic training and circulating neuropeptides in rheumatoid arthritis: a two-year follow-up study.

Previous research has suggested that a short-term (6 week) high-intensity and a subsequent long-term (1 year) low-intensity dynamic training programme in 8 patients with rheumatoid arthritis (RA) increased circulating levels of beta-endorphin (beta-EP) during the high-intensity training and of corticotropin-releasing factor (CRF) and beta-lipotropin (beta-LPH) levels during the low-intensity training, without an increase of pain experience. The present follow-up study of the patients, using the data obtained after an additional 1-year period of no standardized training as reference values, indicated that CRF levels decreased significantly (P less than 0.01) in relation to those obtained 1 year earlier. For beta-LPH and beta-EP, no corresponding decreases were noted. No significant difference concerning experience of pain over time was found. High-performance liquid chromatography demonstrated a complex elution pattern with low basal concentration of beta-LPH, which increased after 60 min of training.

Arthritis, Rheumatoid↗
PubMed1990

Dynamic training and circulating levels of corticotropin-releasing factor, beta-lipotropin and beta-endorphin in rheumatoid arthritis.

The study aimed at evaluating the effects of a dynamic training program on circulating levels of corticotropin-releasing factor (CRF), beta-lipotropin (beta-LPH), and beta-endorphin (beta-EP) in 8 patients (5 females and 3 males, aged 39-65 years) with classical/definite rheumatoid arthritis (RA). Blood samples were collected immediately before, in the middle of, and after a 6-week high-intensity training period as well as after a subsequent 1-year period of low-intensity training. In addition, baseline data were obtained 3 weeks before the start of the training program. Use of multivariate analyses of variance, and of analyses of variance of contrast variables, indicated a short-term effect of the high-intensity training program for beta-EP with increased levels (P less than 0.05) between the 3rd and the 6th weeks, no significant differences being obtained for CRF or beta-LPH here. Corresponding analyses with regard to the combined high and low-intensity training program revealed CRF (P less than 0.01), and beta-LPH (P less than 0.01) levels to increase over time, no long-term effect being found for beta-EP. Despite the intensity of the dynamic training program, no change was found in pain experience as measured on a visual analogue scale.

Adult↗
PubMedDate not supplied

Decreased cerebrospinal fluid neuropeptide Y (NPY) in patients with treatment refractory unipolar major depression: preliminary evidence for association with preproNPY gene polymorphism.

Extensive animal studies suggest neuropeptide Y (NPY) to be involved in coping with a wide range of stressors, and that impaired central NPY signalling could be involved in the pathophysiology of anxiety and depression. Human studies of central NPY levels in depression have, however, been inconclusive. Here, we examined levels of NPY-like immunoreactivity (NPY-LI) in the cerebrospinal fluid (CSF) of medication-free subjects with treatment refractory unipolar depression. Patients were admitted to a research inpatient unit, examined under standardized conditions, and compared with a sample of volunteers in whom psychiatric morbidity was excluded. A robust suppression of NPY levels in patient CSF was found, while other putative CSF markers (monoamine metabolites, somatostatin) did not differ between the groups. We then explored whether this finding might be related to a recently described T1128C coding polymorphism which results in a Leu7-> Pro7 substitution of the signal peptide, and a previously not described T -399C polymorphism in the promoter region of the preproNPY gene. Preliminary evidence was found for an association of both markers with a diagnosis of depression, indicating the possibility of an underlying haplotype influencing the vulnerability for developing depressive illness. Our present findings are in line with an extensive animal literature, and further support the notion that impaired NPY function could contribute to depressive illness.

Adult↗
PubMedDate not supplied

Neurodevelopmental influences on the immune system reflecting brain pathology.

A number of studies have shown that early life events can affect the development of the nervous system, contributing to particular individual differences in later vulnerability to different forms of psychosocial stress related to the environment and lifestyle. Neuropeptides, chemokines (CKs), neurotrophins (NTs) belong to the chemical microenvironment of the cells of the central nervous system (CNS). This paper reviews research performed in our and other laboratories indicating that mass spectrometry should play a significant role in future studies of the structures of proteins/peptides in neuroscience. These applications include peptide metabolism associated with normal and impaired neurone/immune function. Detailed information about peptide/protein processing in the CNS may be studied by using the lymphocyte as a model reflecting different chemical modifications of peptides/proteins related to various psychosomatic disturbances reflecting disorders of environment and lifestyle.

Journal Article↗