| 1. |
- Deshpande, J, et al.
(författare)
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Ultrastructural changes in the hippocampal CA1 region following transient cerebral ischemia: evidence against programmed cell death.
- 1992
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Ingår i: Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale. - 0014-4819. ; 88:1, s. 91-105
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Tidskriftsartikel (refereegranskat)abstract
- The ultrastructural changes in the pyramidal neurons of the CA1 region of the hippocampus were studied 6 h, 24 h, 48 h, and 72 h following a transient 10 min period of cerebral ischemia induced by common carotid occlusion combined with hypotension. The pyramidal neurons showed delayed neuronal death (DND), i.e. at 24 h and 48 h postischemia few structural alterations were noted in the light microscope, while at 72 h extensive neuronal degeneration was apparent. The most prominent early ultrastructural changes were polysome disaggregation, and the appearance of electron-dense fluffy dark material associated with tubular saccules. Mitochondria and nuclear elements appeared intact until frank neuronal degeneration. The dark material accumulated with extended periods of recirculation in soma and in the main trunks of proximal dendrites, often beneath the plasma membrane, less frequently in the distal dendrites and seldom in spines. Protein synthesis inhibitors (anisomycin, cycloheximide) and an RNA synthesis inhibitor (actinomycin D), administered by intrahippocampal injections or subcutaneously, did not mitigate neuronal damage. Therefore, DND is probably not apoptosis or a form of programmed cell death. We propose that the dark material accumulating in the postischemic period represents protein complexes, possibly aggregates of proteins or internalized plasma membrane fragments, which may disrupt vital cellular structure and functions, leading to cell death.
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| 2. |
- Arner, Anders, et al.
(författare)
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Energy turnover and lactate dehydrogenase activity in detrusor smooth muscle from rats with streptozotocin-induced diabetes
- 1993
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 147:4, s. 375-383
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Tidskriftsartikel (refereegranskat)abstract
- Force generation and tissue glucose metabolism were measured in the urinary bladder smooth muscle from rats with streptozotocin-induced diabetes (7-8 wk duration). Bladder wet wt was almost 4-fold higher in the diabetic animals compared with the untreated controls. Morphological analysis showed that the growth was associated with hypertrophy of the smooth muscle component in the bladder wall. Force generation of isolated bladder strip preparations was measured in vitro at different ambient oxygen tensions. Activation of intramural nerves, with electrical field stimulation, induced contractions that were unaffected by reduction of oxygen tension down to PO2 100 mmHg for both control and diabetic muscle strips. At zero PO2 force was reduced by approximately 10-20%, in both groups. High-K+ solution induced 'tonic' contractions that were slightly more inhibited by lowering PO2. At intermediate PO2 (between 100 and 20 mmHg) the diabetic muscle gave slightly higher force. At zero PO2 no significant difference could be detected between strips from control and diabetic animals. Oxygen consumption and lactate production in the preparations were determined at a PO2 of 290 mmHg and related to the volume of smooth muscle. At zero PO2, lactate formation increased 3- to 4-fold. The metabolic tension cost was lower at zero PO2. No differences in basal and contraction related metabolic rates could be detected between the two groups under normoxic and anoxic conditions. The maximal activity of lactate dehydrogenase (LDH) determined in tissue samples was about 2-fold higher in the diabetic bladder muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 3. |
- Arner, Anders, et al.
(författare)
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Metabolism and force in hypertrophic smooth muscle from rat urinary bladder
- 1990
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Ingår i: American Journal of Physiology: Cell Physiology. - 1522-1563. ; 258:5 Pt 1, s. 923-932
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Tidskriftsartikel (refereegranskat)abstract
- Ten days of urinary outlet obstruction in the rat induced a threefold increase in bladder weight. Active force of control and hypertrophic bladder muscle strips was measured at varying PO2 levels after high-K+, carbachol, or electrical field stimulation. Highest force output was obtained with carbachol. Force per muscle area was lower in the hypertrophic muscles. The basal rates of oxygen consumption and lactate formation were similar in the two groups. The metabolic tension cost (ATP turnover/active force) was similar in the two groups for activation with high K+ and carbachol. In anoxia the active force decreased, but this was less pronounced in the hypertrophied muscle. Hypertrophied muscle could, in contrast to the controls, maintain a sustained K+ contracture in anoxia. Basal metabolic rates and tension cost were markedly reduced in anoxia for both groups. The lower force per area with unaltered tension cost, in hypertrophic muscles under all experimental conditions, may reflect unaltered intrinsic properties of the contractile system, although the amount of contractile material has decreased relative to cell volume. The increased resistance to anoxia may reflect a metabolic adaptation to impaired oxygen supply to the hypertrophied tissue.
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| 4. |
- Chen, Y, et al.
(författare)
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Increase in insulin-like growth factor I in hypertrophying smooth muscle
- 1994
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Ingår i: American Journal of Physiology - Endocrinology and Metabolism. - 1522-1555. ; 266:2 Pt 1, s. 224-229
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Tidskriftsartikel (refereegranskat)abstract
- The present study focuses on the role of the insulin-like growth factor (IGF) system in the development of smooth muscle hypertrophy. Hypertrophy was initiated by partial ligation of portal vein or urethra in female Sprague-Dawley rats weighing approximately 220 g. Levels of mRNA were analyzed by solution hybridization. Seven days after ligation, the wet weight of the portal vein was increased about threefold and the concentration of IGF-I mRNA was increased fourfold. The bladder wet weight was increased twofold 3 days after ligation and fourfold 10 days after ligation. IGF-I mRNA in the bladder was elevated 3-fold after 3 days and 2.5-fold after 10 days, whereas IGF binding protein 2 mRNA was increased approximately 2-fold after 3 days and 5-fold after 10 days. IGF-I receptor mRNA in the hypertrophying bladder remained unchanged. Increased levels of IGF-I were demonstrated with immunohistochemistry in both hypertrophying portal vein and urinary bladder. The results show a specific increase in IGF-I mRNA as well as an increased IGF-I immunoreactivity during hypertrophy of smooth muscle, which suggests that the local IGF-system may play a role in smooth muscle hypertrophy.
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| 5. |
- Malmqvist, Ulf, et al.
(författare)
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Contractile and cytoskeletal proteins in smooth muscle during hypertrophy and its reversal
- 1991
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Ingår i: American Journal of Physiology: Cell Physiology. - 1522-1563. ; 260:5, s. 1085-1093
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Tidskriftsartikel (refereegranskat)abstract
- Hypertrophy of rat urinary bladder smooth muscle was induced by partial urethral obstruction. Bladder weight increased from 70 to 240 mg after 10 days and to 700 mg after 7 wk. Removal of the obstruction after 10 days caused a regression of bladder weight to 130 mg. The relative volume of smooth muscle in the bladder wall increased during hypertrophy. The concentration of myosin in the smooth muscle cells decreased in 10-day hypertrophied bladders, whereas the concentration of actin was unchanged. The actin-myosin ratio was 2.3 in controls, 3.3 in 10-day obstructed bladders, and 2.9 in 7-wk obstructed bladders. After removal of obstruction, the ratio was normalized. Two isoforms of myosin heavy chains were identified (SM1 and SM2). The relative amount of SM2 decreased during hypertrophy. The relative proportion of actin isoforms (alpha, beta, and gamma) was altered toward more gamma and less alpha. These changes were reversible upon removal of the obstruction. Desmin was the dominating intermediate filament protein. The concentration of desmin and filamin increased in the hypertrophic bladders. The increased desmin-actin and filamin-actin ratios in obstructed bladders were normalized after removal of the obstruction. The results suggest that the turnover of contractile and cytoskeletal proteins is fast and can be regulated in response to changes in the functional demands in smooth muscle.
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| 6. |
- Malmqvist, Ulf, et al.
(författare)
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Cytoskeletal and contractile proteins in detrusor smooth muscle from bladders with outlet obstruction--a comparative study in rat and man
- 1991
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Ingår i: Scandinavian Journal of Urology and Nephrology. - : Informa UK Limited. - 0036-5599 .- 1651-2065. ; 25:4, s. 261-267
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Tidskriftsartikel (refereegranskat)abstract
- Detrusor biopsies were obtained from patients with urinary outlet obstruction due to prostatic enlargement and from age-matched control patients. The relative amounts of actin and myosin and their isoforms, as well as desmin and filamin were determined and compared with corresponding results from bladders from control rats and rats with 10 days of experimental outlet obstruction of the urinary bladder. In the human control detrusor the actin/myosin ratio was similar to that in the control rat. The isoform distribution of the myosin heavy chains differed between man and rat. In the biopsies from the patients with outlet obstruction and in the obstructed rat bladders the actin/myosin ratio was increased. A change in the myosin heavy chain distribution in the obstructed bladders was observed for both species. The filamin/actin ratio increased significantly in the obstructed rat bladders and tended to increase in the obstructed human bladders. Desmin was the dominating intermediate filament protein. The desmin/actin ratio increased in obstructed bladders in man and in rat.
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| 7. |
- Malmqvist, Ulf, et al.
(författare)
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Mechanics and Ca(2+)-sensitivity of human detrusor muscle bundles studied in vitro
- 1991
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 143:4, s. 373-380
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical properties of isolated smooth muscle strips from human urinary bladder were investigated in vitro. Bladder tissue was obtained from tumour-free wall regions of bladders from male patients undergoing cystectomy for bladder carcinoma. In intact muscle strips, activated with high-K+ solution, half-maximal force occurred at about 0.9 mM extracellular [Ca2+]. The length-active force relation was determined and the muscle strips were fixed for light and electron microscopy at optimal length for active force (1o). The maximal active force per unit smooth muscle cross-sectional area was 208 +/- 49 mN/mm2, n = 6. Chemically skinned preparations were obtained by treatment with triton X-100. These preparations had a steep [Ca2+]-force relation in the micromolar range which was influenced by calmodulin. The skinned preparations could be maximally activated by irreversible thiophosphorylation of the regulatory light chains. The force-velocity relation was determined in the maximally activated skinned muscle at 22 degrees C at 0.51o. When the muscle was shortened by 10%, force was reduced by 35% whereas the maximal shortening velocity was little affected.
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| 8. |
- Brattström, L, et al.
(författare)
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Pyridoxine reduces cholesterol and low-density lipoprotein and increases antithrombin III activity in 80-year-old men with low plasma pyridoxal 5-phosphate
- 1990
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 50:8, s. 873-877
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Tidskriftsartikel (refereegranskat)abstract
- We have previously observed that pyridoxine treatment reduced plasma total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol concentrations and increased antithrombin III (AT III) activity in atherosclerotic patients with subnormal plasma pyridoxal 5-phosphate (PLP) levels. In order to confirm these results, we selected 17 males with low plasma PLP levels from a group of 122 80-year-old males in whom PLP has been determined. After supplementation with 120 mg of pyridoxine per day for 8 weeks their mean plasma TC and LDL cholesterol concentrations were decreased by 10% (p less than 0.01) and 17% (p less than 0.001), respectively. There was no effect on high-density lipoprotein cholesterol and triglycerides but plasma AT III activity was increased by 6% (p less than 0.05). The mechanism by which pyridoxine acts is unclear but it is hypothesized that pyridoxine-derived PLP may enhance the catabolism of LDL and the activity of AT III by inhibiting their glycosylation.
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| 9. |
- Österman, Å, et al.
(författare)
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Effects of 2,3-butanedione monoxime on activation of contraction and crossbridge kinetics in intact and chemically skinned smooth muscle fibres from guinea pig taenia coli
- 1993
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Ingår i: Journal of Muscle Research and Cell Motility. - 0142-4319. ; 14:2, s. 186-194
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Tidskriftsartikel (refereegranskat)abstract
- The effects of 2,3-butanedione monoxime (BDM) were studied in smooth muscle fibres from guinea pig taenia coli. In intact muscle, active force during contractions induced by high-K+ was inhibited by about 10% in 1 mM BDM and by approximately 70% in 10 mM BDM. Intracellular [Ca2+] during contraction, measured with the fura-2 technique, was reduced in the presence of BDM. The reduction in force and [Ca2+] in the presence of 1 and 10 mM BDM could be reproduced by reduction in extracellular Ca2+, suggesting that BDM influences the Ca2+ entry or release. In skinned muscle preparations, BDM decreased the Ca2+ sensitivity of active force. This change could be explained by a decreased level of myosin light chain phosphorylation. In fibres maximally activated by thiophosphorylation, the effect of BDM on force occurred at higher concentrations; 10 mM gave no reduction of force and 60 mM 15% reduction. The maximal shortening velocity (Vmax) and force were unaffected by 30 mM BDM in thiophosphorylated muscle and decreased almost in parallel in Ca(2+)-activated contractions. The present results suggest that BDM inhibits myosin light chain phosphorylation, directly decreases force generation at the crossbridge level and inhibits the Ca2+ translocation in smooth muscle. The effect on force in skinned fibres is observed at higher BDM concentrations than those reported to be required for inhibition of force in striated muscle. The inhibition of force in intact smooth muscle could be explained by an influence on Ca2+ translocation.
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| 10. |
- Vagianos, C, et al.
(författare)
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Effects of alpha-adrenoceptor active drugs, prostaglandin F2 alpha and vasopressin on cystic and hepatic arteries of pig and man
- 1990
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Ingår i: Pharmacology and Toxicology. - 1600-0773. ; 66:2, s. 77-82
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Tidskriftsartikel (refereegranskat)abstract
- Human and pig cystic and pig hepatic arteries were suspended in tissue baths and the effect of alpha-adrenoceptor selective drugs, prostaglandin F2 alpha (PGF2 alpha) and vasopressin were investigated. Prazosin fulfilled the criteria for competitive antagonism in concentrations 10(-9)-10(-7) M. The pA2-values were 9.53 in human cystic, 9.74 in pig cystic, and 9.57 in pig hepatic artery. Rauwolscine had no significant effect in the different arteries. In human cystic artery noradrenaline had significantly (P less than 0.05) higher Emax and pEC50-values (135% of the preceding K(+)-induced contraction and 6.4, respectively) compared with pig cystic (106% and 5.7, respectively) and pig hepatic artery (116% and 5.9, respectively). Vasopressin had no effect in the cystic arteries, whereas it had a high potency (pEC50 was 8.5) but low intrinsic activity (Emax was 14%) in pig hepatic artery. Prostaglandin F2 alpha had a significantly higher Emax in human than in pig arteries. No differences were found in pEC50-values. This study indicates a similarity in pharmacological characteristics of some vasoactive drugs especially between pig cystic and hepatic arteries. If this is also true in man, the easily obtainable cystic artery can be used for screening the effect of drugs on the hepatic artery.
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