| 1. |
- Edström, A., et al.
(författare)
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Axonal outgrowth and neuronal apoptosis in cultured adult mouse dorsal root ganglion preparations : Effects of neurotrophins, of inhibition of neurotrophin actions and of prior axotomy
- 1996
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522. ; 75:4, s. 1165-1174
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Tidskriftsartikel (refereegranskat)abstract
- Dorsal root ganglia (L4 and L5) with attached spinal roots and nerve stumps were isolated from young adult mice and cultured in a layer of extracellular matrix material (matrigel). Within one day, a large number of axons grew out from the cut ends of the nerve and the dorsal root. The average outgrowth length was more than doubled by nerve growth factor, which also strongly increased the number of fibres, showing extensive branching. There was also a significant outgrowth stimulation by neurotrophin-3, but no observable effect by brain-derived neurotrophic factor. In preparations isolated and cultured six days after peripheral nerve transection in vivo, there was an increase in both the outgrowth length (about 1.5- to 2-fold) and in the number of axons. Stimulation of axonal outgrowth, which concerned outgrowth from both the peripheral nerve and the dorsal root, could be further enhanced by the addition of nerve growth factor to the culture. K-252a, a selective inhibitor of neurotrophin receptor-associated tyrosine kinase activity, did not affect either the normal outgrowth or the increased outgrowth in pre-axotomized preparations, at a concentration which abolished the stimulating effects by exogenous nerve growth factor and neurotrophin-3. Under the culturing conditions used, spontaneous apoptosis occurred, but none of the neurotrophins tested, nor K-252a, affected the number of apoptotic neuronal cells analysed by nick-labelling DNA breaks at the end of a 48-h culturing period. Altogether, the present data suggest that for most dorsal root ganglia neurons, signalling through the trk receptors does not influence the apoptosis in vitro and is not required for either the spontaneous axonal outgrowth in matrigel or the increased outgrowth which occurs after prior axotomy in vivo.
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| 2. |
- Edström, Anders, et al.
(författare)
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Moderate elevation of extracellular potassium transiently inhibits regeneration of sensory axons in cultured adult sciatic nerves
- 1995
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Ingår i: Brain Research. - 0006-8993. ; 693:1-2, s. 148-154
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Tidskriftsartikel (refereegranskat)abstract
- The adult frog dorsal root ganglia (DRG) together with the sciatic nerve (ScN) has previously been shown to survive in organ culture for several days. If a local test crush is made at the beginning of culturing, there is an initial delay of about 3 days before the sensory axons start to grow into the distal nerve stump at a rate of about 0.6-0.9 mm/day. The present results showed that axonal growth was unaffected in preparations maintained for 8 days in medium containing 10 mM K+ (5 mM is the physiological level). In contrast, the outgrowth was markedly reduced by 15 mM K+ and still more by 20 and 25 mM K+. The growth inhibition was partially counteracted by nifedipine, a Ca2+-channel antagonist. Other experiments clearly showed that high K+ exerted its effects during the early phase of the regeneration and lacked effects at later stages. The possibility that Ca2+-binding proteins, e.g., calbindin, which showed immunohistochemical reactivity in different structures, contribute to the growth adaptation to high K+ will be considered. The generality of the findings was supported by inhibition of axonal outgrowth of adult mouse sciatic sensory axons by high K+.
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| 3. |
- Edström, A., et al.
(författare)
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Phospholipase A2 activity is required for regeneration of sensory axons in cultured adult sciatic nerves
- 1996
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Ingår i: Journal of Neuroscience Research. - 0360-4012. ; 43:2, s. 183-189
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Tidskriftsartikel (refereegranskat)abstract
- The adult frog dorsal root ganglia (DRGs) and their sciatic nerves (ScN) survive in organ culture for several days. About 3 days after a local test crush, the sensory axons start to regenerate into the distal nerve stump at a rate of approximately 0.6-0.9 mm/day. The axonal outgrowth is inhibited in a non-toxic way by low concentrations of three different phospholipase A2 (PLA2) inhibitors: 4-bromophenacyl bromide (BPB), aristolochic acid, and oleyl-oxyethyl-phosphoryl-choline (OOPC). In contrast, the outgrowth was slightly stimulated by 0.2 μM melittin, a PLA2 activator. Most experiments refer to the effects of BPB, which was shown to almost completely inhibit outgrowth at a concentration which did not affect either ganglionic protein synthesis or axonal transport. Using a compartmental system it could clearly be shown that BPB exerted its action in the outgrowth region. Other experiments showed that the initial period (about 3 days), which precedes the outgrowth, was unaffected by BPB. Several structures, including axonal ones, showed immunoreactivity for the low molecular form of PLA2 (sPLA2). The results suggest that PLA2 activity plays an important role in nerve regeneration and exerts its action at a local level, where the growth cones move forward.
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| 4. |
- Ekström, Per
(författare)
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Increased cyclic AMP in in vitro regenerating frog sciatic nerves inhibits Schwann cell proliferation bur has no effect on axonal outgrowth
- 1995
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Ingår i: Journal of Neuroscience Research. - : Wiley. - 0360-4012. ; 42:1, s. 54-62
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Tidskriftsartikel (refereegranskat)abstract
- In the present study the role of cAMP for axonal outgrowth and Schwann cell proliferation was studying using the cultured frog sciatic nerve. An intrinsic rise in nerve injury, both in vitro and in vivo. Treatment with 0.1‐1.0μM forskolin, an activator of the cAMP‐generating enzyme adenylyl cyclase, increased the cAMP content up to 13‐fold, but was yet without effect on axonal outgrowth during an 8‐day culturing period. HA‐1004, an inhibitor of cAMP‐dependent protein kinase, also lacked effect on the regeneraton. In contrast, the proliferation of Schwann cells, measured as [3H]thymidine incorporation, was inhibited to about 70% of control by forskolin, whereas HA‐1004 stimulated proliferation to approximately 130% of control. The results suggest that cAMP is involved in the injury‐induced proliferation of Schwann cells of an adult peripheral nerve but that it lacks a central role in the regeneration of sensory axons of such nerves. © 1995 Wiley‐Liss, Inc.
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| 5. |
- Ekström, Per, et al.
(författare)
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The immune modulator Linomide prevents neuronal death in injured peripheral nerves of the mouse
- 1998
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Ingår i: NeuroReport. - 0959-4965. ; 9:7, s. 1337-1341
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Tidskriftsartikel (refereegranskat)abstract
- Neuronal death after injury or disease could result from imbalanced cytokine expression. Linomide (LS-2616, quinoline-3-carboxamide), a synthetic immunomodulator with effects on cytokine production, suppresses autoimmune diseases of the nervous system. Here adult mice were pre-treated with 200 mg/kg/day of Linomide for 9 days, after which the sciatic nerves were crushed. After another 10 days of Linomide treatment the dorsal root ganglia were dissected out and stained for apoptosis, either immediately or after 2 days in culture, which increases cell death. Superior cervical ganglia were also cultured for 2 days. The Linomide pretreatment profoundly reduced (~60- 80%) the injury-induced apoptotic death of neurons and satellite cells in both systems. The results suggest that modulation of the inflammatory cytokine cascade is a promising road to nerve cell rescue.
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| 6. |
- Hedlund, Petter, et al.
(författare)
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Heme oxygenase and NO-synthase in the human prostate--relation to adrenergic, cholinergic and peptide-containing nerves
- 1997
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Ingår i: Journal of the Autonomic Nervous System. - : Elsevier. - 0165-1838 .- 1872-7476. ; 63:3, s. 115-126
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Tidskriftsartikel (refereegranskat)abstract
- In the human prostate, the distribution of heme oxygenase (HO-1 and HO-2)-, nitric oxide synthase (NOS)-, and tyrosine hydroxylase (TH)-immunoreactive (IR), acetylcholine-esterase (AChE)-positive, and some peptidergic nerve structures was investigated. Cell bodies and nerve fibers within coarse nerve trunks expressed HO-1-, HO-2-, NOS-, TH-, and vasoactive intestinal polypeptide (VIP)-immunoreactivities, and were AChE-positive, but, as revealed by confocal microscopy. HO- and NOS-immunoreactivities were found in separate nerves. Along strains of smooth muscle, intraglandular septa, and around acini, HO-1-, NOS-, and VIP-IR nerves, and AChE-positive fibers were observed. Double immunostaining showed that NOS- and VIP-immunoreactivities were generally co-localized in varicose nerve terminals. Some TH-IR terminals had profiles that were similar, but not identical, to those of NOS-, HO-1-, or VIP-IR terminals. NPY-IR nerves were similarly distributed as VIP- and NOS-IR fibers, and were found in rich amounts. Calcitonin gene-related peptide (CGRP)-IR nerves were few compared to other nerve populations studies. NOS- and CGRP-IR terminals had similar profiles, but the immunoreactivities were not co-localized. Nitric oxide and electrical stimulation of nerves relaxed noradrenaline-contracted preparations of prostatic stroma. Inhibition of synthesis of nitric oxide abolished the electrically induced relaxations. VIP had small relaxant effects, whereas carbon monoxide was without effect on noradrenaline-contracted strips. The innervation pattern and the functional effects suggest that the L-arginine/nitric oxide pathway may have a role in the control of human prostatic smooth muscle activity and/or in secretory neurotransmission. A physiological role of carbon monoxide in the prostate remains to be established.
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| 7. |
- Hornfelt, M., et al.
(författare)
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Involvement of axonal phospholipase A2 activity in the outgrowth of adult mouse sensory axons in vitro
- 1999
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Ingår i: Neuroscience. - 0306-4522. ; 91:4, s. 1539-1547
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Tidskriftsartikel (refereegranskat)abstract
- The effect on axonal outgrowth of inhibition of phospholipase A2 activity was studied in a recently developed in vitro model, where dorsal root ganglia with attached spinal roots and nerve stumps from young adult mice were cultured in an extracellular matrix material (Matrigel). The phospholipase A2 inhibitors 4-bromophenacyl bromide and oleyloxyethyl phosphorylcholine dose-dependently reduced axonal outgrowth from the sciatic nerve stump. A similar inhibitory effect was seen when only the cut nerve end was exposed to the inhibitors in a compartmental culture system. The local effect of phospholipase A2 inhibition was further investigated on axons established in culture, using time-lapse recording. Exposure to phospholipase A2 inhibitors caused the retraction of filopodia extensions and a reduction in growth cone motility within a few minutes. After removal of inhibition, normal growth cone motility and axonal growth were regained. Nerve cell bodies and axons, in contrast to Schwann cells, showed immunoreactivity after staining with an antiserum against secretory phospholipase A2, and elevated levels of the enzyme could be detected after culture for 24 h. The immunoreactive protein was of approximately 170,000 molecular weight (phospholipase A2-170) as determined by sodium dodecyl sulphate- polyacrylamide gel electrophoresis and immunoblotting. The localization of phospholipase A2-170 in axons growing into the Matrigel was also demonstrated by use of a whole-mount technique. The results of this study show the importance of continuous phospholipase A2 activity for growth cone motility and axonal outgrowth in the mammalian peripheral nerve, and suggest the involvement of an axonally localized enzyme.
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| 8. |
- Hornfelt, M., et al.
(författare)
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Upregulation of cytosolic phospholipase A2 correlates with apoptosis in mouse superior cervical and dorsal root ganglia neurons
- 1999
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Ingår i: Neuroscience Letters. - 0304-3940. ; 265:2, s. 87-90
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Tidskriftsartikel (refereegranskat)abstract
- The involvement of cytosolic phospholipase A2 (cPLA2) in apoptosis of adult mouse superior cervical and dorsal root ganglia neurons has been investigated by the use of immunohistochemistry for cPLA2 and DNA nick-end labeling for apoptotic cells, respectively, cPLA2 immunoreactivity was strongly upregulated in neurons of both preparations during in vitro culturing. By double labeling it was unequivocally demonstrated that cPLA2 was present and upregulated only in neurons undergoing apoptosis. A similar picture emerged when cPLA2 immunoreactivity was compared with staining with Fluoro-Jade, a novel fluorochrome marker for neuronal degeneration. The preferential presence of cPLA2 in apoptotic and degenerating cells suggests that the enzyme is important for some mechanism involved in or intimately coupled to neuronal cell death.
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| 9. |
- Islam, M. Shahidul, et al.
(författare)
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In situ activation of the type 2 ryanodine receptor in pancreatic beta cells requires cAMP-dependent phosphorylation
- 1998
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 95:11, s. 6145-6150
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Tidskriftsartikel (refereegranskat)abstract
- Molecular mechanisms that regulate in situ activation of ryanodine receptors (RY) in different cells are poorly understood. Here we demonstrate that caffeine (10 mM) released Ca2+ from the endoplasmic reticulum (ER) in the form of small spikes in only 14% of cultured fura-2 loaded beta cells from ob/ob mice. Surprisingly, when forskolin, an activator of adenylyl cyclase was present, caffeine induced larger Ca2+ spikes in as many as 60% of the cells. Forskolin or the phosphodiesterase-resistant PKA activator Sp-cAMPS alone did not release Ca2+ from ER. 4-Chloro-3-ethylphenol (4-CEP), an agent that activates RYs in other cell systems, released Ca2+ from ER, giving rise to a slow and small increase in [Ca2+]i in beta cells. Prior exposure of cells to forskolin or caffeine (5 mM) qualitatively altered Ca2+ release by 4-CEP, giving rise to Ca2+ spikes. In glucose-stimulated beta cells forskolin induced Ca2+ spikes that were enhanced by 3,9-dimethylxanthine, an activator of RYs. Analysis of RNA from islets and insulin-secreting betaTC-3-cells by RNase protection assay, using type-specific RY probes, revealed low-level expression of mRNA for the type 2 isoform of the receptor (RY2). We conclude that in situ activation of RY2 in beta cells requires cAMP-dependent phosphorylation, a process that recruits the receptor in a functionally operative form.
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| 10. |
- Johansson, Christer, et al.
(författare)
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Svavel- och kvävenedfalletöver Stockholms län
- 1997
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten presenterar resultat från spridningsberäkningar och mätningar av svavel- ochkvävenedfallet för perioden oktober 1994 — september 1995 (ett hydrologiskt år). Förberäkningarna används spridningsmodeller som utvecklats speciellt för Stockholms länoch som ingår i miljöövervakningssystemet som drivs av Luftvårdsförbundet i Stockholmslän.Modellberäkningarna ger halter av svaveldioxid och kväveoxider för varje timme med4x4 kilometers upplösning i hela länet. Torr- och våtdepositionen har summerats tillmånadsvärden. För beräkningarna används en detaljerad emissionsdatabas samt resultatenfrån ett stort antal mätningar av meteorologi, deposition, krondropp och föroreningshaltersom genomförts inom ramen för Luftvårdsförbundets och Länsstyrelsensregionala miljöövervakning. Beräkningarna jämförs med mätningar.Våtdepositionen av svavel och kväve är till största delen beroende av nederbördens geografiskafördelning, som varierar kraftigt p g a lokala klimatförhållanden. I genomsnittsyns två områden med förhållandevis hög nederbörd — inre delarna av Södertörn ochnorra delarna av Norrtälje kommun. I dessa områden är nederbördsmängden nästandubbelt så stor som över de yttre delarna av skärgården, där de minsta mängderna förekommer.Som mest noteras drygt 900 mm nederbörd för det hydrologiska året 1994/95.Detta är ca. 30% högre än de genomsnittligt högsta värdena för 10 år (1984 — 1993).Den relativa geografiska fördelningen av årsnederbörden 1994/95 skiljer sig inte väsentligtfrån den genomsnittliga fördelningen under de senaste 10 åren.Den högsta våtdepositionen av svavel sker över Södertörn med drygt 6 kg S/ha/år. I yttreskärgården ligger värdena på omkring 3 till 4 kg/ha/år. För kväve är motsvarande siffrordrygt 7 kg N/ha/år respektive 4 kg N/ha/år. Den geografiska fördelningen av torrdepositionenbestäms i hög grad av var utsläppen sker. Beräkningarna visar på mycket skarpagradienter med den högsta torrdepositionen i Stockholmsregionen och lägre värden utmot landsbygden och skärgården. Högsta torrdepositionen av svavel och kväve beräknasuppgå till 5 kg S/ha/år respektive 7 kg N/ha/år, vilket är drygt hälften av den totala depositionen.Som mest uppgår den totala depositionen (summan av våt- och torrdepositionen) avsvavel och kväve till drygt 9 kg S/ha/år respektive 12 kg N/ha/år. Det lägsta nedfallet,som sker över landsbygdsområden och skärgården, är på knappt hälften av de högstavärdena. I hela länet överskrids de undre kritiska belastningsgränserna för både svaveloch kväve.Bidragen till nedfallet från utsläpp av kväve och svavel i Stockholms län har beräknatsmed hjälp av spridningsmodellen. För kväve kan drygt 50% av den totala depositionen iStorstockholm härledas till utsläppen i länet. För svavel är motsvarande siffra 30% —40%.- 5 -Utanför tätortsområdena har utsläppen inom länet endast liten betydelse för den totaladepositionen. Här står intransporterade svavel- och kväveföreningar för huvuddelen.Mätningarna visar att halterna i luften som transporteras in är jämnt fördelade över länet.De geografiska variationerna i depositionen över landsbygden och skärgården ärdärför dels beroende av nederbördens fördelning, som bestämmer variationen i våtdeposition,dels markanvändningen, som påverkar variationen i torrdeposition.Det enda säkra sättet att bedöma noggrannheten i beräkningarna är att så långt det gårjämföra beräknade halter, deposition och nederbörd med uppmätta värden (i vissapunkter). För nederbörden erhålls en god beskrivning på de flesta platserna. I genomsnittför 12 mätstationer är beräknad årsnederbörd inom 2% av uppmätt värde. Under sommarenkan dock avvikelserna bli stora p g a mycket stora variationer i nederbördsmängdernaför olika platser i länet.När det gäller kväveoxidhalter (NOx och NO2) erhålls en god överensstämmelse mellanberäkningar och mätningar i Stockholms innerstad. Beräknade månadsmedelvärden liggerför de flesta månaderna inom 20% av uppmätta värden. För svaveldioxidhalterna(SO2) är skillnaden större speciellt för sommarmånaderna då halterna är mycket låga.Beräknat totalt nedfall av svavel stämmer relativt väl med krondroppsmätningarna. Beräknattotalt nedfall av kväve kan däremot inte jämföras med kvävenedfallet i krondropp,eftersom träden tar upp en avsevärd del av det kväve som tillförs skogen via luftoch nederbörd.
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