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| 2. |
- Enoksson, Staffan, et al.
(författare)
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Marked Re-Utilization of Free Fatty Acids During Activated Lipolysis in Human Skeletal Muscle.
- 2005
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 90:2, s. 1189-1195
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Tidskriftsartikel (refereegranskat)abstract
- Release of glycerol and free fatty acids (FFA) was investigated in human skeletal muscle strips. In the basal state, glycerol and FFA were released at almost equimolar rates (0.3 nmol/ng tissue.90 min). A nonselective beta-adrenoceptor agonist, isoprenaline, caused a concentration-dependent stimulation of glycerol release, whereas FFA release was unaffected. Basal and isoprenaline-induced glycerol release correlated positively with the age of the donors (r = 0.5, P < 0.005) but not with their body mass index (P > or = 0.4). Biochemical experiments with hormone-sensitive lipase (HSL) showed that most enzyme activity was both in the cytosol and mitochondrial fraction and that it constituted the common long and active form of the protein. Electron microscopy studies in rat skeletal muscle using labeled highly specific HSL antibodies verified the cytosolic location of HSL and, furthermore, indicated an accumulation of HSL-adjoining mitochondria. These results suggest that FFA produced in myocytes during catecholamine-induced lipolysis are retained by the muscle and, therefore by inference, reused. It is conceivable that efficient hydrolysis of acylglycerol by HSL located in the cytosol as well as near the mitochondria may facilitate mitochondrial FFA oxidation. In addition, muscle lipolysis activity increases during aging and may be independent of total body fat.
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| 3. |
- Hansen, Joakim, 1978-, et al.
(författare)
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Våtmarker som fiskevårdsåtgärd vid kusten : utvärdering av restaurerade våtmarkers effekt på fiskreproduktion och ekosystemet längs Östersjökusten
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Många av Östersjöns kustfiskar är av sötvattenursprung och fortplantar sig i grunda vikar och kustnära våtmarker. Historiska utdikningar, kustexploatering och övergödning har lett till förluster av fiskens lek- och uppväxtområden, vilket tillsammans med fiske bidragit till minskande bestånd av exempelvis gädda och abborre. För att motverka nedgången har flera förvaltningsåtgärder initierats.Ungefär 100 våtmarker har restaurerats längs svenska ostkusten för att gynna reproduktionen av gädda och abborre. I samma syfte har fiskvandringshinder i kustmynnande vattendrag tagits bort på cirka 40 platser.Det fåtal uppföljningar som genomförts visar att sådana åtgärder har en god potential att bidra till stärkta kustbestånd av gädda och abborre. Mängden gäddyngel i kustvattnen utanför våtmarkerna tenderar att öka kraftigt efter åtgärderna, medan ingen tydlig förändring kan ses för mängden abborryngel. Det är dock stor variation i utfallet. En studie indikerar även en tydlig lokal ökning av gäddbestånden i kustvattnen utanför våtmarkerna. Sammanställningen visar även att borttagning av vandringshinder i kustmynnande vattendrag förbundna med olika sjösystem kan vara en effektivare metod än att restaurera våtmarker för attgynna abborre, vilket bör undersökas vidare.Det finns få studier som specifikt undersökt om åtgärderna kan ge så stark effekt på rovfiskbestånden att det indirekt påverkar resten av födoväven och ekosystemet. Det finns en potential för sådan påverkan. Men ökningen av rovfisk till följd av de åtgärdade våtmarkerna har i dagsläget inte varit tillräckligt kraftig för att leda till tydliga ekosystemeffekter, så som mindre mängd bytesfisk och påväxtalger.Även om våtmarker kan ge en lokal ökning av mängden fisk måste fler och kompletterande åtgärder till för att stärka kustens rovfiskbestånd. Åtgärderna bör utformas som en del av en tydligt samordnad och långsiktig förvaltning av kust och hav. Förutom en starkare reglering av kustfisket behövs exempelvis bättre skydd mot exploatering av fiskens lek- och uppväxtområden. Även lokal reduktion av mängden gråsäl och storskarv kan vara en möjlig åtgärd i områden där dessa rovdjur medför hög dödlighet på gädda och abborre.Utformningen av fiskeriförförvaltningen i öppet hav måste ha en mer rigid tillämpning av ekosystemansatsen och beakta konsekvenser för kustens ekosystem. Exempelvis tyder mycket på att förändringar i utsjöns fiskbestånd är en viktig bidragande orsak till att storspigg har ökat kraftigt de senaste decennierna. Storspiggen migrerar mellan utsjö och kust. Eftersom den äter gädd- och abborryngel minskar möjligheten att med lokala åtgärder stärka rovfiskbestånden vid kusten.Sammanställningen visar på en bristfällig koordinering och uppföljningav det senaste decenniets fiskevårdsåtgärder. För att skapa en bättre kunskapsbas för framtida förvaltningsbeslut finns därför ett behov av fler och samordnade mångåriga uppföljningar av åtgärder på såväl yngelproduktionoch lokala fiskbestånd som på kustekosystemet.
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| 4. |
- Mukka, Sebastian S., et al.
(författare)
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Osteoclasts in periprosthetic osteolysis : the charnley arthroplasty revisited
- 2017
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Ingår i: The Journal of Arthroplasty. - : Elsevier. - 0883-5403 .- 1532-8406. ; 32:10, s. 3219-3227
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Periprosthetic osteolysis by polyethylene wear debris-triggered osteoclasts is viewed as the main pathophysiological pathway in aseptic loosening in total hip arthroplasty. The present aim was to study osteoclast occurrence in osteolytic lesions in early and late revisions of the Charnley low-friction torque arthroplasty (CLFA).METHODS: Biopsies of the soft interface membrane and the adjacent bone were taken from osteolytic lesions during revision of 16 loose CLFA, early (2-6 years) or late (>10 years) after primary surgery. By light microscopy (LM), cell-dense regions with signs of osteoclast-mediated bone resorption were selected for transmission electron microscopy. Three additional patients were studied in LM for osteoclast markers (tartrate-resistant acid phosphatase and Cathepsin K).RESULTS: LM disclosed a low-grade chronic inflammation and birefringent particles in most sections. Multiple conglomerates of tartrate-resistant acid phosphatase positive and Cathepsin K positive mononuclear and multinucleated cells were found deep in the fibrous interface membrane. Transmission electron microscopy showed traces of polyethylene-like particles in 67%-100% of the cells. Osteoclast-like cells exhibiting resorptive activity were few (mean, 0.7%; standard deviation, 0.2%), and multinucleated cells, possibly osteoclast precursor cells, located immediately on the bone were also scarce (mean, 2.7%; standard deviation, 5.3%). Multinucleated (odds ratio, 3.0; 95% confidence interval, 1.7-5.5) and macrophage-like cells (odds ratio, 3.6; 95% confidence interval, 2.2-5.6) were typically located deeper in the inflammatory interface membrane with a pathologic appearance with distension and abundance of phagocytic vacuoles. There were no systematic differences in cell populations between early or late revisions.CONCLUSION: Despite probable ongoing osteoclastogenesis in the osteolytic lesions, there were few sites of osteoclast-mediated bone resorption. These findings attach a contributing biological explanation to the longevity of the CLFA.
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| 5. |
- Nordahl, Joakim
(författare)
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Matrix resorption in endochondral bone growth : ultrastructural studies, with special attention to the chondroclast
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A substantial amount of the calcified cartilage in the distal parts of the epiphyseal plate is resorbed during endochondral growth of long bones. However, the mechanisms involved in this process are still largely unknown. On the other hand, bone-resorption in the lower metaphysis has been thoroughly investigated. Since bone and cartilage are tissues with different composition, our hypothesis was that the resorption mechanisms may also be separate. At the epiphyseal/metaphyseal border, cells with a morphology resembling the osteoclasts are present. They are by some authors designated chondroclasts. However, their specific properties regarding morphological and functional features have not received much attention. In the present study, Sprague-Dawley rats were used to investigate some aspects of matrix resorption in calcified cartilage compared with bone. Four groups of animals were analyzed mainly at the ultrastructural level; one normal group, one group with impaired tissue resorption due to nutritionally induced vitamin D deficiency rickets, and two groups of animals healing from rickets at 48 or 72 hours after introduction of normal food. Our results are based on a number of measurements of cellular parameters at the ultrastructural level and expression of markers for chondroclasts/ostcoclasts; ie tartrate-resistant acid phosphatase (TRAP) and cathepsin K. We also wanted to clarify the role of the extracellular matrix proteins bone sialoprotein, osteopontin and fibronectin. Since they all contain an Arg-Gly-Asp (RGD) sequence, they may bind to integrin receptors on cell surfaces, making them potentially active in cell-matrix adhesion, as an initial step in the resorption sequence. Our approach with quantitative morphology and immunohistochemistry was aimed at demonstrating even smaller differences between cells and tissue compartments than are normally detected by qualitative means. In summary we showed that chondroclasts and osteoclasts were different regarding some characteristic morphometric features, indicating differences in resorption mechanisms between bone and cartilage. Furthermore, we identified a previously unrecognized structure at the cell-matrix border with features of both ruffled borders and clear zones, i.e. the traditional resorption characteristics. This structure was designated the intermediate zone, suggested to be a transient stage in the development of ruffled border within an established clear zone. Bone sialoprotein located outside the clear zone of chondroclasts has a potential role in interaction between these cells and their adjacent matrix. Fibronectin is associated with collagen type I in bone and may be involved in collagen fibril formation or mineralization, but is apparently not involved in cell-matrix interaction in highly differentiated cartilage or bone. The role of osteopontin, observed in the ruffled border area of chondroclasts, remains to be clarified. In rickets, clast-like cells are able to establish a cell-matrix interaction. However, development of the ruffled border is interrupted, paralleled by absence of extracellular enzyme release onto the matrix surface. Restitution of traditional ultrastructural resorption characteristics, at 48 hours after introduction of normal food, coincides largely with secretion of cathepsin K to the matrix surface, rendering this enzyme suitable as a marker for active resorption. As TRAP was not secreted in any significant amounts until at 72 hours, this enzyme may be involved in termination of the resorption sequence.
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