PubMed Health⌕ Search

Biomedical subjects

B Jakobsen

Publications and source records attributed to B Jakobsen.

At least 19 recordsLinked to original sources
PubMed2005

Characterization of organotypic ventral mesencephalic cultures from embryonic mice and protection against MPP toxicity by GDNF.

We characterized organotypic ventral mesencephalic (VM) cultures derived from embryonic day 12 (E12) mice (CBL57/bL6) in terms of number of dopaminergic neurons, cell soma size and dopamine production in relation to time in vitro and tested the effects of 1-methyl-4-phenylpyridinium (MPP(+)) and glial derived neurotrophic factor (GDNF) to validate this novel culture model. Dopamine production and dopaminergic neuron soma size increased dramatically with time in vitro, whereas the number of dopamine neurons declined by approximately 30% between week 1 and week 2, which was further reduced after week 4. GDNF treatment (100 ng/mL) increased dopaminergic neuron soma size (up to 43%) and DOPAC production (approximately three-fold), but not the number of dopamine neurons in control cultures. One-week-old cultures were more vulnerable to MPP(+), than three-week-old cultures. The EC(50) for dopamine depletion after 2 days exposure and 15 days of recovery were 0.6 and 7 microm, respectively. Both pre-treatment and post-treatment with GDNF are important to obtain maximal protection against MPP(+) toxicity. In one-week-old cultures (5 microm MPP(+), 2 days) GDNF provided potent neuroprotection with dopamine contents reaching control levels and number of tyrosine hydroxylase (TH)(+) cells up to 80% of control, but in three-week-old cultures (10 microm MPP(+), 2 days) the protective potential of GDNF was markedly reduced. Long recovery periods after MPP(+) exposure are required to distinguish between reversible or irreversible toxic and/or trophic effects.

1-Methyl-4-phenylpyridinium↗
PubMed2002

Domoic acid neurotoxicity in hippocampal slice cultures.

The neurotoxicity of domoic acid was studied in 2-3 week old rat hippocampal slice cultures, derived from 7 day old rat pups. Domoic acid 0.1-100 microM was added to the culture medium for 48 hrs, alone or together with the glutamate receptor antagonists NS-102 (5-Nitro-6,7,8,9-tetrahydrobenzo[G]indole-2,3-dione-3-oxime), NBQX (2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo(F)quinoxaline) or MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine hydrogen maleate), followed by transfer of the cultures to normal medium for additional 48 hrs. Neuronal degeneration in the fascia dentata (FD), CA3 and CA1 hippocampal subfields was monitored and EC(50) values estimated by densitometric measurements of the cellular uptake of propidium iodide (PI). The CA1 region was most sensitive to domoic acid, with an EC(50) value of 6 microM domoic acid, estimated from the PI-uptake at 72 hrs. Protective effects of 10 microM NBQX against 3 and 10 microM domoic acid were observed for both dentate granule cells and CA1 and CA3c pyramidal cells. NS102 and MK 801 only displayed protective effects when combined with NBQX. MK801 significantly increased the combined neuroprotective effect of NBQX and NS102 against 10 microM domoic acid in both CA1 and FD, but not in CA3. We conclude, that domoic acid neurotoxicity in CA3 and in hippocampal slice cultures in general primarily involves AMPA/kainate receptors. At high concentrations (10 microM domic acid) NMDA receptors are, however, also involved in the toxicity in CA1 and FD.

Animals↗
PubMed2001

Chronic exposure of kainate and NBQX changes AMPA toxicity in hippocampal slice cultures.

Receptor agonist/antagonist mediated modulation of the excitotoxic effect of AMPA was studied in organotypic hippocampal slice cultures. Treatment of developing cultures for 2 weeks with a subtoxic dose of 2 microM kainate reduced the toxicity of 3 microM AMPA, applied for 48 h with 24 h of recovery, as measured by cellular uptake of the fluorescent dye propidium iodide. In contrast long-term treatment with 0.3 microM of the AMPA/KA antagonist NBQX increased the susceptibility of the cultures to an even lower dose of 2 microM AMPA. The modulatory effects of long-term application of low doses of kainate and NBQX, have implications for the development and use of related drugs that aim to protect against glutamate receptor-mediated disturbances.

Animals↗
PubMed2000

Excitatory amino acid neurotoxicity and modulation of glutamate receptor expression in organotypic brain slice cultures.

Using organotypic slice cultures of hippocampus and cortex-striatum from newborn to 7 day old rats, we are currently studying the excitotoxic effects of kainic acid (KA), AMPA and NMDA and the neuroprotective effects of glutamate receptor blockers, like NBQX. For detection and quantitation of the induced neurodegeneration, we have developed standardized protocols, including--a) densitometric measurements of the cellular uptake of propidium iodide (PI), --b) histological staining by Flouro-Jade, --c) lactate dehydrogenase (LDH) release to the culture medium, --d) immunostaining for microtubulin-associated protein 2, and --e) general and specific neuronal and glial cell stains. The results show good correlation between the different markers, and are in accordance with results obtained in vivo. Examples presented in this review will focus on the use of PI uptake to monitor the excitotoxic effects of --a) KA and AMPA (and NMDA) in hippocampal slice cultures, and --b) KA and AMPA in corticostriatal slice cocultures, with demonstration of differentiated neuroprotective effects of NBQX in relation to cortex and striatum and KA and AMPA. A second set of studies include modulation of hippocampal KA-induced excitotoxicity and KA-glutamate receptor subunit mRNA expression after long-term exposure to low, non-toxic doses of KA and NBQX. We conclude that organotypic brain slice cultures, combined with standardized procedures for quantitation of cell damage and receptor subunit changes is of great potential use for studies of excitotoxic, glutamate receptor-induced neuronal cell death, receptor modulation and related neuroprotection.

Animals↗
PubMed1999

Excitotoxic effects of non-NMDA receptor agonists in organotypic corticostriatal slice cultures.

The excitotoxic effects of the glutamate receptor agonists kainic acid (KA) and 2-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and the corresponding neuroprotective effects of the AMPA/KA receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX) were examined in corticostriatal slice cultures. The purpose was to examine the feasibility of these cultures for excitotoxic studies, and to demonstrate possible differential excitotoxic effects of KA and AMPA on striatal and cortical neurons. Slices of dorsolateral striatum with overlying neocortex were obtained from neonatal rats and grown on semiporous membranes in serum-free medium for 3-4 weeks before exposure to KA or AMPA for 48 h. The uptake by injured cells of the fluorescent dye propidium iodide (PI) added to the culture medium was used as a quantifiable measure for neuronal degeneration and compared with efflux of the cytosolic enzyme lactate dehydrogenase (LDH) into the culture medium and loss of glutamic acid decarboxylase (GAD) activity in the tissue. Histological sections were also stained by the fluorescent dye Fluoro-Jade (FJ), for degenerating neurons and by immunocytochemical staining for gamma-aminobutyric acid (GABA). Digitized images showed a dose (0-24 microM KA, 0-6 microM AMPA) and time (0-48 h) dependent increase in PI uptake in both striatum and cortex. In other cultures exposed to KA (24 microM) or AMPA (6 microM) together with NBQX (0.1-9 microM), NBQX was found to exert a differential neuroprotective effect on striatum and cortex at low doses. NBQX was thus more protective against KA in the cortex than in the striatum, while the opposite was seen in relation to AMPA. Regarding neurodegenerative markers, PI uptake was significantly correlated with (1) LDH release into the culture medium, (2) optical density of Fluoro-Jade staining, (3) loss of GAD-activity in tissue homogenates, and (4) loss of GABA-immunostained neurons. We conclude that both differences between compounds (AMPA vs. KA) and brain areas (striatum vs. cortex) can be demonstrated in corticostriatal slice cultures, which in conjunction with an established set of markers for neuronal cell damage appears to be a feasible model for studies of the neurotoxic and neuroprotective effects of glutamate receptor agonists and antagonists.

Animals↗
PubMed1999

Coupling of organotypic brain slice cultures to silicon-based arrays of electrodes.

Fetal or early postnatal brain tissue can be cultured in viable and healthy condition for several weeks with development and preservation of the basic cellular and connective organization as so-called organotypic brain slice cultures. Here we demonstrate and describe how it is possible to establish such hippocampal rat brain slice cultures on biocompatible silicon-based chips with arrays of electrodes with a histological organization comparable to that of conventional brain slice cultures grown by the roller drum technique and on semiporous membranes. Intracellular and extracellular recordings from neurons in the slice cultures show that the electroresponsive properties of the neurons and synaptic circuitry are in accordance with those described for cells in acutely prepared slices of the adult rat hippocampus. Based on the recordings and the possibilities of stimulating the cultured cells through the electrode arrays it is anticipated that the setup eventually will allow long-term studies of defined neuronal networks and provide valuable information on both normal and neurotoxicological and neuropathological conditions.

Animals↗
PubMed1992

DNA polymorphism of HLA class II genes in primary biliary cirrhosis.

We investigated the DNA restriction fragment length polymorphism of the major histocompatibility complex class II genes: HLA-DRB, -DQA, -DQB, DPA, -DPB, the serologically defined HLA-A, B, C, DR antigens, and the primed lymphocyte typing defined HLA-DP antigens in 23 Danish patients with primary biliary cirrhosis (PBC) and in healthy Danes. The following genetic markers were found with increased frequencies in PBC: HLA-B8 (relative risk, RR = 2.4, P less than 0.05, 'corrected' P greater than 0.05), HLA-DR3 (RR = 3.4, P less than 0.01, 'corrected' P less than 0.05), the DRB3*01/02/03 (DRw52) associated DRB Bgl II 9.1 kilobase (kb) fragment (RR = 2.9; P less than 0.05, 'corrected' P greater than 0.05), the DQA1*0501 associated DQA Taq I 4.8 kb fragment (RR = 3.1; P less than 0.05, 'corrected' P greater than 0.05), the DQB1*0201 (DQw2) associated DQB Hin dIII 11.5 kb fragment (RR = 3.1; P less than 0.05, 'corrected' P greater than 0.05). No DNA fragments specific for DRB1*0301 (DR3) could be identified. The frequencies in PBC of other genetic markers including DRw8, DRB1*08, HLA-DP antigens, DPA, and DPB genes did not differ significantly from those in controls. The associations between PBC and B8, DR3, DQA1*0501, and DQB1*0201, which are frequently found together on the same haplotype, are at variance with recent reports on associations between PBC and Drw8. The discrepancy suggests that PBC is genetically heterogenous.

Genes, MHC Class II↗
PubMed1988

Association between HLA-DR2 and production of tumour necrosis factor alpha and interleukin 1 by mononuclear cells activated by lipopolysaccharide.

The production of tumour necrosis factor (TNF) and interleukin 1 (IL-1) by lipopolysaccharide-activated mononuclear cells from 39 healthy donors was studied in vitro by bioassay and ELISA. The donors were typed for HLA-A, -B, -C, -DR, and -DP antigens. There was no detectable production of TNF beta (lymphotoxin). The intracellular levels of bioactive TNF alpha were minimal or undetectable in all cases. Cells from HLA-DR2+ individuals secreted significantly lower amounts of TNF alpha than cells from HLA-DR2- donors [2 ng/ml (1.5-4.4) and 7.5 ng/ml (3.9-8.3) respectively (medians 25-75%); P less than 0.01]. The difference disappeared if the cells were preactivated for 2 days with 1000 U/ml of recombinant gamma interferon (rIFN-gamma). In some individuals, the TNF alpha response increased considerably after IFN-gamma priming, in particular in those possessing the HLA-DR2 antigen. In contrast, there was no detectable difference in the production of IL-1 beta between the donors, and the IL-1 beta response decreased significantly after rIFN-gamma priming in HLA-DR2+ individuals [2.3 ng/ml (1.1-8.4) versus 7.2 ng/ml (5-7.9); P less than 0.05] and in HLA-DR2- individuals [3 ng/ml (1.1-5.3) versus 5.7 ng/ml (3.9-7.5); P less than 0.01]. There was no correlation between the TNF alpha and IL-1 responses and any of the other HLA-DR, -DP, or -B antigens. There was a significant positive correlation between the levels of TNF alpha measured by ELISA and by cytotoxicity assay. However, the TNF alpha-containing supernatants from 9 out of 37 individuals appeared to contain inhibitor(s) of the biological activity of TNF alpha. The presence of inhibitor(s) was not associated with any HLA antigens.

Adult↗
PubMed1987

Restriction fragment length polymorphism of the HLA-DP subregion and correlations to HLA-DP phenotypes.

The restriction fragment length polymorphism (RFLP) of the class II HLA-DP subregion of the major histocompatibility complex (MHC) of humans has been unraveled by Southern blotting using DP alpha and DP beta probes in a study of 46 unrelated individuals with known HLA-DP types. Contrary to earlier preliminary findings with a limited number of enzymes, the RFLP appears to be quite extensive both with the DP beta (14 different DNA markers defined by individual fragments or clusters thereof) and the DP alpha (8 markers) probes, especially when enzymes recognizing only four base pairs were used. A few markers were absolutely or strongly associated with individual DP antigens, whereas most were associated with two or more DP antigens as defined by primed lymphocyte typing. Thus, Southern blotting seems feasible for typing for most DP determinants by specific fragments or subtraction between the various more broadly reactive DNA markers, and the RFLP provides further information on the DP subregion in addition to that provided by primed lymphocyte typing. In two recombinant families, the DP beta and DP alpha DNA markers segregated with DP antigens, whereas the DR beta, DQ beta, DQ alpha, and DX alpha markers followed the DR and DQ antigens.

Chromosome Mapping↗
PubMed1985

Studies of HLA-ABC and DR antigens in pure atopic dermatitis and atopic dermatitis combined with allergic respiratory disease.

The HLA-ABC antigens were investigated in 29 patients with pure atopic dermatitis and 43 patients with atopic dermatitis combined with atopic respiratory disease (ARD). Furthermore, the DR antigens were studied in 10 patients with dermatitis alone and in 24 patients with combined atopic disease. The frequencies of antigens and the HLA phenotypes A1, B8 and A3, B7 in the entire group of patients and in two subgroups did not differ significantly from those in controls, when correction was made for the number of comparisons made. However, the frequency of HLA-DR7 was strikingly low, but this observation needs confirmation. IgE levels were measured in eight patients with pure dermatitis and in 24 patients with dermatitis combined with ARD and found equally increased in both groups compared to controls.

Adolescent↗