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Biomedical subjects

E Hansson

Publications and source records attributed to E Hansson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Extent of intercellular calcium wave propagation is related to gap junction permeability and level of connexin-43 expression in astrocytes in primary cultures from four brain regions.

Astrocytes are coupled via gap junctions, predominantly formed by connexin-43 proteins, into cellular networks. This coupling is important for the propagation of intercellular calcium waves and for the spatial buffering of K+. Using the scrape-loading/dye transfer technique, we studied gap junction permeability in rat astrocytes cultured from four different brain regions. The cultures were shown to display regional heterogeneity with the following ranking of the gap junction coupling strengths: hippocampus = hypothalamus > cerebral cortex = brain stem. Similar relative patterns were found in connexin-43 messenger RNA and protein levels using solution hybridization/RNase protection assay and western blots, respectively. The percentages of the propagation area of mechanically induced intercellular calcium waves for cortical, brain stem and hypothalamic astrocytes compared with hippocampal astrocytes were approximately 77, 42, and 52, respectively. Thus, the extent of calcium wave propagation was due to more than just gap junctional permeability as highly coupled hypothalamic astrocytes displayed relatively small calcium wave propagation areas. Incubation with 5-hydroxytryptamine decreased and incubation with glutamate increased the calcium wave propagation area in hippocampal (67% and 170% of the control, respectively) and in cortical astrocytes (82% and 163% of the control, respectively). Contrary to hippocampal and cortical astrocytes, the calcium wave propagation in brain stem astrocytes was increased by 5-hydroxytryptamine incubation (158% of control), while in hypothalamic astrocytes, no significant effects were seen. Similar effects from 5-hydroxytryptamine or glutamate treatments were observed on dye transfer, indicating an effect on the junctional coupling strength. These results demonstrate a strong relationship between connexin-43 messenger RNA levels, protein expression, and gap junction permeability among astroglial cells. Furthermore, our results suggest heterogeneity among astroglial cells from different brain regions in intercellular calcium signaling and in its differential modulation by neurotransmitters, probably reflecting functional requirements in various brain regions.

Animals↗
PubMed1999

Distinct pharmacological properties of ET-1 and ET-3 on astroglial gap junctions and Ca(2+) signaling.

Astrocytes represent a major target for endothelins (ETs), a family of peptides that have potent and multiple effects on signal transduction pathways and can be released by several cell types in the brain. In the present study we have investigated the involvement of different ET receptor subtypes on intercellular dye diffusion, intracellular Ca(2+) homeostasis, and intercellular Ca(2+) signaling in cultured rat astrocytes from hippocampus and striatum. Depending on the ET concentration and the receptor involved, ET-1- and ET-3-induced intracellular Ca(2+) increases with different response patterns. Both ET-1 and ET-3 are powerful inhibitors of gap junctional permeability and intercellular Ca(2+) signaling. The nonselective ET receptor agonist sarafotoxin S6b and the ET(B) receptor-selective agonist IRL 1620 mimicked these inhibitions. The ET-3 effects were only marginally affected by an ET(A) receptor antagonist but completely blocked by an ET(B) receptor antagonist. However, the ET-1-induced inhibition of gap junctional dye transfer and intercellular Ca(2+) signaling was only marginally blocked by ET(A) or ET(B) receptor-selective antagonists but fully prevented when these antagonists were applied together. The ET-induced inhibition of gap junction permeability and intercellular Ca(2+) signaling indicates that important changes in the function of astroglial communication might occur when the level of ETs in the brain is increased.

Animals↗
PubMed1999

Brain primary cultures and vibrodissociated cells as tools for the study of astroglial properties and functions.

The glial cells, especially the astroglia constitute a prominent part of the brain cell volume. Astroglial properties are difficult to study in the intact nervous system. For that reason, different in vitro models have been developed. The development of cell and tissue cultivation conditions has been the prerequisite to our present knowledge of the biochemistry and pharmacology of glial cells and to some extent even neurons. It is, however, an advantage if results from tissue culture can be evaluated in more in vivo like systems. We here describe a method for acute isolation of freshly prepared neurons and glial cells.

Animals↗
PubMed1998

The attachment protein of Hendra virus has high structural similarity but limited primary sequence homology compared with viruses in the genus Paramyxovirus.

The complete nucleotide sequence of the attachment protein gene of Hendra virus, a new member of the subfamily Paramyxovirinae, has been determined from cDNA clones derived from viral genomic RNA. The deduced mRNA is 2565 nucleotides long with one open reading frame encoding a protein of 604 amino acids, which is similar in size to the attachment protein of the members of the subfamily. However, the mRNA transcript is >600 nucleotides longer than others in the subfamily due to the presence of long untranslated regions at both the 5' and 3' ends. The protein is designated G because it lacks both hemagglutination and neuraminidase activities. It contains a hydrophobic transmembrane domain close to the N terminus, eight potential N-linked glycosylation sites, and 18 cysteine residues. Although the HeV G protein had low sequence homology with Paramyxovirinae members, the predicted folding pattern of its extracellular globular head was very similar to that of members of the genus Paramyxovirus, with the location of seven potential pairs of sulfide bonds absolutely conserved. On the other hand, among the seven residues known to be critical for neuraminidase activity, only one was conserved in the Hendra virus G protein compared with at least six in HN proteins of paramyxoviruses and rubulaviruses and four in H proteins of morbilliviruses. The biological significance of this finding is discussed.

Amino Acid Sequence↗
PubMed1998

Receptor-activated Ca2+ increases in vibrodissociated cortical astrocytes: a nonenzymatic method for acute isolation of astrocytes.

A new nonenzymatic method for the acute isolation of astrocytes from rat cerebral cortex is described. A vibratory device was used to dissociate the cells from thin brain slices, and the method yielded fresh and relatively well-preserved astrocytes without previous enzyme incubation. These cells were examined in a microspectrofluorometric system for measurement of changes in intracellular free calcium concentrations ([Ca2+]i), and their expression of various neurotransmitter receptors was determined. Acutely isolated glial fibrillary acidic protein (GFAP)-positive astrocytes (p7-p18) were seen to respond to the metabotropic glutamate receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD, 10(-4) M) with increases in [Ca2+]i, and this response was blocked by (RS)-1-aminoindan-1,5 dicarboxylic acid (AIDA, 10(-3) M), an antagonist to group 1 metabotropic glutamate receptors. The delta-opioid receptor agonist D-Pen2, D-Pen5-enkephalin (DPDPE, 10(-6) M) evoked [Ca2+]i increases that were blocked by the delta-opioid antagonist ICI 174.388 (10(-5) M). The astrocytes failed to respond to 5-hydroxytryptamine (5-HT, 10(-5) M), although the same cells subsequently were found to respond to other agonists. Furthermore, [Ca2+]i responses evoked by phenylephrine (10(-5) M) were blocked by prazosin (0.2x10(-6) M), suggesting the expression of alpha1-adrenergic receptors on the acutely isolated astrocytes. The cells were also shown to react with [Ca2+]i increases in response to depolarization with high extracellular potassium concentrations (50x10(-3) M). The signals induced by depolarization were not seen in Ca2+-free buffer, indicating the presence of voltage-activated calcium channels in these cells. Thus, the present study confirms some of the results earlier obtained in cell cultures, suggesting that cortical astrocytes in vivo express glutamate, opiate, and adrenergic receptors, coupled to increases in [Ca2+]i, whereas no receptors for 5-HT could be detected.

Animals↗
PubMed1998

Intracellular sulfatide expression in a subpopulation of astrocytes in primary cultures.

A highly specific antibody against sulfatide, a myelin-associated glycolipid, has been investigated using indirect double immunocytochemistry in rat primary astroglial cultures from cerebral cortex. Sulfatide was expressed in a selected subpopulation of astrocytes (2-3%) and was found to be exclusively located intracellularly. The sulfatide-positive cells appeared in two different morphologies: flat and stellate. Immunolabeling of the astroglial cultures showed that sulfatide always co-existed with GFAP or S-100, and in some cells with GD3 (flat 90% and stellate 50%) or A2B5 (1%) antibody. The sulfatide-positive cells did not bind the O1 antibody, which is used as a marker for oligodendrocytes. Glial cultures from other regions and mixed cultures, with both neurons and glial cells, were examined and showed similar results. Biochemical analysis by TLC-ELISA verified the presence of sulfatide in the astroglial culture and showed decreasing amounts of sulfatide with days in vitro; 0.05 nmol/mg protein at day 10 and 0.01 nmol/mg protein at day 17. This analysis also showed that neither sulpholactosylceramide nor seminolipid was present, each of which also has affinity for the sulfatide antibody. This selective and intracellular expression encourages further identification of the astrocytes expressing sulfatide and the biological role of sulfatide in these cells.

Animals↗
PubMed1998

Modulation of mechanically induced calcium waves in hippocampal astroglial cells. Inhibitory effects of alpha 1-adrenergic stimulation.

The effects of different adrenoceptor agonists were investigated on mechanically induced Ca2+ waves in astroglial cells in astroglial-neuronal mixed cultures from rat hippocampus. In the initial part of the study some properties of the waves were characterized. The results show that the initiation of the Ca2+ waves was not critically dependent on extracellular Ca2+ but both the calcium signal and the propagation area of the calcium wave were significantly reduced when the experiments were performed in Ca2+-free buffer. In addition, using the phospholipase C (PLC) inhibitor U-73122 (1 microM) and the gap junction uncoupler octanol (1 mM), the results showed that the Ca2+ wave propagation required PLC activation and functional gap junctions. Further, the data also showed that the protein kinase C (PKC) activator phorbol-12-myristate-13-acetate (PMA 150 nM) reduced the spreading of the waves. The adrenoceptor agonists isoproterenol (iso; beta), phenylephrine (phe; alpha1) and clonidine (clon; alpha2) were evaluated for their short-term (<30 s) effects on the wave propagation. The propagation area was persistently decreased 1, 3 and 5 min after removal of phe. No effects were observed after incubation with iso or clon. Furthermore, using U-73122 or PMA together with phe, shortly incubated, the experiments showed that PLC was a central regulator in the initial phase of the initiation procedure of wave propagation. However, under these conditions PKC was shown not to be involved. Instead it appeared that PKC exerted its inhibitory action on the Ca2+ waves in a latter phase, after prolonged phe exposure. Taken together, the results show that the propagation of Ca2+ waves between astroglial cells in primary cultures can be inhibited/regulated in two principally different ways which involve a pronounced time component. The results also further point out the adrenergic signaling system as an important mediator of dynamic neuron-astroglial information exchange.

1-Octanol↗
PubMed1998

Regulation of the glial glutamate transporter GLT-1 by glutamate and delta-opioid receptor stimulation.

The excitatory effect of presynaptically released glutamate is tightly regulated and terminated by high affinity sodium-dependent glutamate transporters. The regulation of the glial glutamate transporter GLT-1 is potentially important in synaptic modulation. Using astroglial cultures prepared from the rat cerebral cortex, we found that the delta-opioid receptor agonist [D-pen2,D-pen5]-enkephalin decreases and glutamate increases the expression of the GLT-1 transporter mRNA. Corresponding changes in the uptake kinetics were found after incubation for 48 h with the respective agonists when glial glutamate uptake was measured in primary astroglial cultures. The data suggest that long-term receptor activation induces alterations in glial glutamate uptake properties.

ATP-Binding Cassette Transporters↗
PubMed1998

Bladder dysfunction: an integral part of the ectopic ureterocele complex.

PURPOSE: We evaluate whether bladder dysfunction is common in patients with ectopic ureterocele and, if so, whether it is an integral part of the ectopic ureterocele complex or a result of surgery. MATERIALS AND METHODS: From 1986 to 1995, 34 patients with a mean age of 10 months were treated for large or medium ectopic ureteroceles at our institution and 32 participated in postoperative followup. Bladder function was investigated by a careful history and repeat uroflowmetry, and residual urine estimation was assessed by ultrasound and cystometry. RESULTS: Of the 32 patients 19 had infrequent voiding and 3 had incontinence. Cystometric bladder capacity was increased to greater than 150% of the normal value for age in 15 of 27 patients (55%). Uroflowmetry revealed greater than 5 ml. residual urine in 15 patients (56%). Postoperatively no radiological signs of bladder neck obstruction were found. Increased bladder capacity and residual urine did not correlate with ureterocele size or location, or surgical procedure. There was no progression of bladder dysfunction with age. CONCLUSIONS: Children with ectopic ureterocele are at high risk for a high capacity bladder with incomplete emptying. This bladder dysfunction associated with ectopic ureterocele does not seem to be the result of surgery but an integral part of the disorder.

Female↗
PubMed1998

Delta-opioid receptors on astroglial cells in primary culture: mobilization of intracellular free calcium via a pertussis sensitive G protein.

Astrocytes in primary culture from rat cerebral cortex were probed concerning the expression of delta-opioid receptors and their coupling to changes in intracellular free calcium concentrations ([Ca2+]i). Fluo-3 or fura-2 based microspectrofluorometry was used for [Ca2+]i measurements on single astrocytes in a mixed astroglial-neuronal culture. Application of the selective delta-opioid receptor agonist, [D-Pen2, D-Pen5]-enkephalin (DPDPE), at concentrations ranging from 10 nM to 100 microM, induced concentration-dependent increases in [Ca2+]i (EC50 = 114 nM). The responses could be divided into two phases, with an initial spike in [Ca2+]i followed by either oscillations or a sustained elevation of [Ca2+]i. These effects were blocked by the selective delta-opioid receptor antagonist ICI 174864 (10 microM). The expression of delta-opioid receptors on astroglial cells was further verified immunohistochemically, using specific antibodies, and by Western blot analyses. Pre-treatment of the cells with pertussis toxin (100 ng/ml, 24 h) blocked the effects of delta-opioid receptor activation, consistent with a Gi- or Go-mediated response. The sustained elevation of [Ca2+]i was not observed in low extracellular Ca2+ and was partly blocked by nifedipine (1 microM), indicating the involvement of L-type Ca2+ channels. Stimulating neurons with DPDPE resulted in a decrease in [Ca2+]i, which may be consistent with the closure of the plasma membrane Ca2+ channels on these cells. The current results suggest a role for astrocytes in the response of the brain to delta-opioid peptides and that these opioid effects in part involve altered astrocytic intracellular Ca2+ homeostasis.

Animals↗
PubMed1998

Stimulation of 5-HT2A receptors on astrocytes in primary culture opens voltage-independent Ca2+ channels.

Mechanisms underlying the 5-HT2A receptor induction of intracellular Ca2+ mobilization and Ca2+ influx in type I astroglial cells in primary culture from newborn rat cerebral cortex were evaluated. The 5-HT-evoked Ca(2+)-transients, inhibited by the 5-HT2A antagonists ketanserin or 4-(4-fluorobenzoyl)-1-(4-phenylbutyl) piperidine oxalate, consisted of an initial peak caused by inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ release from internal stores, and a second sustained part which was due to Ca2+ transport over the plasma membrane. The responses were pertussis toxin-insensitive, suppressed by the phospholipase C inhibitor neomycin and were inhibited by the Ca(2+)-ATPase inhibitor thapsigargin. Furthermore, the responses were inhibited by the IP3 receptor antagonist heparin. When the second sustained part of the 5-HT-evoked response was studied, it was concluded that Ca2+ influx was not a result of opening of voltage operated calcium channels of either L, N or T-type. Instead it appeared that Ca2+ entered the cells through specialized voltage independent Ca2+ channels which were dependent of the IP3 production and subsequent Ca2+ release from internal stores. From this, we conclude that 5-HT opens Ca2+ channels in astrocytes which closely resemble depletion-operated Ca2+ channels (DOCCs).

Animals↗
PubMed1998

Treatment of Deep Vein Thrombosis with Low Molecular Weight Heparin at Patient's Home.

We have applied the low molecular weight heparin dalteparin as once-daily subcutaneous injections to the treatment of deep vein thrombosis (DVT) on an outpatient basis since 1994. Until today, 377 consecutive patients with DVT below the inguinal ligament have been treated at home with dalteparin. The patients administered the injections themselves or with the help of either a relative or a primary nurse. Here we report the outcome of the 212 patients treated during 1994-1995, which has been followed for 2 years after the start of treatment. At the 2-year follow-up only 13 patients (6.6%) had suffered a recurrent DVT and of these none were on continuous dicumarol treatment. No cases of major bleedings were seen. This new therapeutic approach for the treatment of DVT is safe, most of the patients are able to treat themselves, and the patients are satisfied with the home treatment model.

Journal Article↗
PubMed1998

Sequence analysis of the Hendra virus nucleoprotein gene: comparison with other members of the subfamily Paramyxovirinae.

The nucleoprotein (N) gene of Hendra virus (HeV), an unclassified member of subfamily Paramyxovirinae in the family Paramyxoviridae previously known as equine morbillivirus, was cloned and sequenced. The majority of the deduced amino acid sequence was further confirmed by direct sequencing of peptide fragments of the N protein derived from purified virions. The 3' untranslated sequence of the HeV N gene mRNA was 568 nt and was much longer than that observed in other Paramyxovirinae. The N protein was 532 amino acids in length with a molecular mass of 58.5 kDa. Although the HeV N protein had a slightly higher amino acid sequence identity to those of the genus Morbillivirus than to those of other Paramyxovirinae genera, the level of identity was much lower than that observed within the morbilliviruses. Our results indicated that HeV could not confidently be classified as a member of the genus Morbillivirus, Paramyxovirus or Rubulavirus and suggest that the virus be classified in a new genus within the Paramyxovirinae.

Amino Acid Sequence↗
PubMed1998

Life expectancy and cost utility after total hip replacement.

In a prospective study of 410 cemented hip replacements in 372 patients with a mean age of 71 years, mortality after 8 years was 33%. Mortality for patients with osteoarthrosis was lower than in an age matched control population, probably because of a preoperative selection of patients. An estimate of costs and adjusted quality of life has shown that total hip replacement has a good cost utility even in the elderly patient. The conclusion of this study is that the indications for hip replacement in the elderly patient can be expanded. Such patients should undergo surgery earlier in the course of their disease.

Adult↗
PubMed1997

Adrenoceptor-induced changes of intracellular K+ and Ca2+ in astrocytes and neurons in rat cortical primary cultures.

The calcium- and potassium sensitive fluorescent dyes fura-2 and K+-binding benzofuran isophtalate (PBFI) were used to detect changes in [Ca2+]i and [K+]i in type 1 astrocytes and neurons in mixed astroglial/neuronal rat cortical primary cultures after adrenoceptor stimulation. Noradrenalin (NA), phenylephrine (phe; alpha1-agonist), clonidine (clon; alpha2-agonist) and isoproterenol (iso; beta-agonist) were used. All agonists were able to increase [Ca2+]i and decrease [K+]i in the astrocytes with the exception of clon, which could not induce potassium responses. In the neurons, NA and phe evoked calcium transients while clon and iso did not. NA and clon were able to elicit reductions in [K+]i but no responses were seen after phe or iso stimulation. In neurons, the NA-evoked reductions in [K+]i always appeared immediately and gradually (after 30-50 s) returned to baseline even in the presence of the agonists. On the other hand, in the astrocytes, the NA-induced reductions in [K+]i appeared with some latency and always persisted at the lower level in the presence of the agonists. In addition, external tetraethylammonium (TEA) could severely reduce the NA-induced K+ responses in the astrocytes. The results indicate a clear heterogeneity regarding both adrenoceptor expression and response characteristics between astroglial cells and neurons.

Adrenergic Agonists↗
PubMed1997

[D-Pen2,5]enkephalin and glutamate regulate the expression of delta-opioid receptors in rat cortical astrocytes.

Recent work from our and other laboratories have shown that glial cells in culture express opioid receptors. In the present study we have analyzed the regulation of delta-opioid receptor mRNA and the regulation of delta-opioid receptor activated astroglial Ca2+ responses in primary cultures from the rat cerebral cortex. Astroglial cultures were incubated with glutamate (Glu) or [D-Pen2,5]enkephalin (DPDPE) for 48 h, and delta-opioid receptor mRNA levels were analyzed using a solution hybridization RNase protection assay. Our results suggest that incubation in Glu or DPDPE upregulates the abundance of delta-opioid receptor mRNA in a dose dependent way. Glu incubated cells showed a maximum upregulation at the highest agonist concentration used (10[-5] M), whereas DPDPE was most effective at low concentrations (l0[-9] M). Furthermore, corresponding Ca2+ imaging experiments showed that incubation in Glu or DPDPE upregulated the responding frequency of delta-opioid receptor activated glial calcium fluxes from a control value of 5% to 14% and 17% responding cells, respectively.

Aniline Compounds↗