Marianne Wikgren
Åbo Akademi University
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Featured researches published by Marianne Wikgren.
Cell and Tissue Research | 1985
Margaretha K. S. Gustafsson; Marianne Wikgren; T. J. Karhi; L. P. C. Schot
SummaryThe present immunocytochemical study concerns the distribution of four neuropeptides, FMRF-amide, vasotocin, leu-enkephalin and neurotensin, and of the bioamine serotonin in the plerocercoid larva of Diphyllobothrium dendriticum. Anti-FMRF-amide and vasotocin-reactivity occurs in perikarya and nerve fibres in the CNS and PNS of this worm. The peptide-containing fibres surround and seem to innervate the musculature and to terminate beneath the basal lamina of the tegument at the inner surface of the bothridia, suggesting a neurotransmitter function. Antileu-enkephalin reaction occurs in perikarya and fibres in the main nerve cords and in the PNS. Anti-neurotensin reactive fibres were observed in the neuropile of the nerve cords. Serotonin immunoreactivity was found in neurons in the ganglionic commissure of the brain and along the main nerve cords. This study is the first immunocytochemical identification of neuropeptides and serotonin in a parasitic flatworm and the information gained may be of importance for the development of new antihelminthics.
Journal of Documentation | 2005
Marianne Wikgren
Purpose – The philosophical position known as critical realism is briefly introduced, and some of its central features are used to connect the philosophy and the realist social theory to some current library and information science (LIS) models of information behaviour.Design/methodology/approach – The paper uses a literature‐based analysis of the critical realism concepts of a stratified social reality, the importance of contextualisation, and the relation between structure and agency. These features are discussed in relation to various models of information‐seeking behaviour, but also to the “interpretative” approach to information as meaning which can only be achieved through discourses in a human community.Findings – The critical realism perspective could lay a fruitful foundation for an interdisciplinary research field like LIS, and its user studies in particular, concerned with many levels of information creation, seeking, use and processing. It is the task of the LIS researcher to explain the mecha...
Peptides | 1985
Marianne Wikgren; Maria Reuter
A whole mount immunofluorescence method was used for the localization of immunoreactivity (IR) to four regulatory peptides and the bioamine serotonin in the nervous system of Stenostomum leucops (Turbellaria, Platyhelminthes). The flatworm S. leucops belongs to the taxon Catenulida which, according to the new phylogenetic system by Ax [2], forms a key group between the coelenterates and more advanced flatworm species. Positive IR was obtained using antisera against FMRF-amide, beta-endorphin, growth hormone releasing factor (GRF), substance P, and serotonin. The distribution patterns of these neuropeptide-like immunoreactivities differ significantly from each other. Antisera against Leu-enkephalin, bovine pancreatic polypeptide (BPP), bombesin, cholecystokinin (CCK-8), neurotensin, somatostatin, growth hormone (GH), secretin, and neurophysin II gave negative results. This primitive flatworm shows similarities with hydra in the lack of IR to anti-somatostatin, anti-Leu-enkephalin, and anti-BPP. These antisera give positive IR in more advanced flatworm species, indicating a later convergent evolution of vertebrate-like peptides within the phylum Platyhelminthes.
Library & Information Science Research | 2001
Marianne Wikgren
Abstract The Internet is a convenient but complex source for health information used by an increasing number of health consumers. Especially for people suffering from a chronic illness (e.g., diabetes), information seeking forms a part of the daily management of the disease, a “project of life.” This study of Web texts examines the citation patterns for a specific and controversial health issue: the beneficial or hazardous use of dietary chromium supplementation in diabetes self-management. Texts from different categories of Web sources (scientific, professional, educational, and commercial sources, as well as diabetes discussion groups) were analyzed in order to study how knowledge is transferred between sources, and how diabetics participating in discussion groups refer to and make sense of the information from different sources on the Internet. The citation patterns suggest that deviations from the traditional models of scientific knowledge dissemination can occur in the Internet environment.
Hydrobiologia | 1986
Marianne Wikgren; Maria Reuter; Margaretha K. S. Gustafsson
The nervous systems of the turbellarians Microstomum lineare and Polycelis nigra and of the cestodes Diphyllobothrium dendriticum and Schistocephalus solidus were studied by means of the peroxidase- antiperoxidase (PAP) immunocytochemical method, with the use of antisera to the neuropeptides FMRF- amide, vasotocin, leu-enkephalin, met-enkephalin, neurotensin, somatostatin, and VIP, and to the bioamine serotonin. Anti-FMRF-amide positive perikarya and fibers occurred in all species, while the occurrence of the vertebrate brain-gut peptides and serotonin varied between the species. Anti-somatostatin and anti-VIP gave a negative result. Anti-FMRF-amide and anti-vasotocin positive immunoreactivity was found in the brain and gut of M. lineare, and in the CNS and the peripheral nerve net of the cestodes. We suggest that the brain-gut peptides of free-living flatworms act on the subtegumental region in the cestodes, which lack a gut but absorb their nutrients directly through the tegument.
Parasitology Research | 1989
Margareth K. S. Gustafsson; Marianne Wikgren
Neurons immunoreactive to small cardiac peptide B (SCPb) occur in the scolex and neck region of adultDiphyllobothrium dendriticum. The localisation of the SCPb-IR neurons in the peripheral nervous system is very pronounced; they are closely associated to the bothridial musculature in the scolex. SCPb-IR neurons were not observed in plerocercoid larvae but appeared after cultivation in vitro at 37°C for 30 h. Functional and developmental aspects of the SCPb-IR neurons are discussed.
Cell and Tissue Research | 1990
Marianne Wikgren; Maria Reuter; Margaretha K. S. Gustafsson; Paula Lindroos
SummarySpecific antibodies against histamine were used to demonstrate the occurrence and cellular distribution of histamine-like immunoreactivity in three species of flatworms (phylum Platyhelminthes). In the parasitic cestode Diphyllobothrium dendriticum, histamine-reactivity was found in neurons of the main nerve cords, and in cells lining the central and peripheral excretory ducts. In the free-living microturbellarian Microstomum lineare and in the planarian Polycelis nigra, histamine-immuno-reactivity was restricted to cells and fibres of the nervous system. The occurrence of histamine or a related substance in the nervous system of flatworms, which represent primary bilateria, indicates the importance of this neuroactive substance in the animal kingdom.
Parasitology Research | 1980
Margaretha K. S. Gustafsson; Marianne Wikgren
The peptidergic and aminergic neurons in adultDiphyllobothrium dendriticum were studied by light and electron microscopy, combined with fluorescence histochemistry (Falck-Hillarp method for biogenic amines). The peptidergic neurons, regarded as presumptive neurosecretory cells, are located close to the central as well as the peripheral nervous system. These neurons are characterized by their large electron-dense granules. They have very long processes extending to the musculature and the basement membrane of the tegument. The aminergic neurons show the fluorescence characteristic of 5-hydroxytryptamine and contain small dense-core granules. They are located in the brain commissure and along the main nerve cords. Fine nerves reach the muscular and subtegumental layers. Their distribution thus parallels that of the peptidergic neurons, indicating a possible interdependence between the two types of neurons.
Cell and Tissue Research | 1986
Maria Reuter; Marianne Wikgren; Marjut Lehtonen
SummaryA whole mount immunofluorescence method is used for an investigation of immunoreactivity (IR) to anti-(a-) 5-HT and anti-(a-)FMRF-amide in the nervous system (NS) of Microstomum lineare (Turbellaria, Macrostomida, Platyhelminthes). New details of the organization of the NS are demonstrated, differences in 5-HT and FMRF amide IR are revealed, and new information on the development of the NS in zooids is obtained. In contrast to previous reports of a reduction (one pair of nerve cords without transverse processes) of the basic turbellarian plan, IR to both antisera reveals three pairs of longitudinal nerve cords, and features of the orthogonal organization, characterized by transverse commissures. The lateral pair of nerve cords is the most prominent. The following differences in the patterns of 5-HT and FMRF-amide IR are observed: 1. Perikarya positive for a-5-HT and a-FMRF-amide in the brain show different localizations. 2. Perikarya positive for a-5HT occur along the main lateral nerve cords, while the cords visualized by FMRF-amide IR look double-stranded and lack associated perikarya. 3. 5-HT IR is observed in a postpharyngeal commissure, which is absent in the a FMRF-amide-stained preparations. 4. In developing zooids 5-HT IR is first observed in the postpharyngeal commissure and later on in an increasing number of perikarya and in the neuropile. The first FMRF-amide IR in developing zooids appears in the cerebral commissure and in two perikarya in front of this commissure.
Archive | 1980
Maria Reuter; Marianne Wikgren; Irmeli Palmberg
SummaryThe nervous system (NS) of Microstomum lineare (Turbellaria, Macrostomida) was studied by electron and light microscopy, combined with fluorescence histochemistry (Falck-Hillarp method for biogenic monoamines). The NS is primitively organized, with a bilobed brain, two lateral nerve cords lacking commissures, and peripheral nerve cells scattered along the nerve cords. The stomatogastric NS, with a pharyngeal nerve ring, is joined to the central NS by a pair of connective ganglia. A green fluorescence in all parts of the NS indicates catecholaminergic neurons as the dominant neuron type.Ultrastructurally, two types of neurons were identified on the basis of their vesicle content: 1. Aminergic (catecholaminergic) neurons containing densecore vesicles of varying electron-density and size, i.e., small dense-core vesicles (diameter 50–100 nm), vesicles with a highly electron-dense core (60–140 nm), and vesicles with an eccentric dense-core. 2. Presumed peptidergic neuro-secretory neurons containing large granular vesicles (diameter about 200 nm) in the stomatogastric NS and peripheral parts of the central NS. In light microscopy, paraldehyde-thionin stained neurons were observed in the same areas.