| 1. |
- Arner, Anders, et al.
(författare)
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Effects of Ca2+ on force-velocity characteristics of normal and hypertrophic smooth muscle of the rat portal vein
- 1985
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 124:4, s. 525-533
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Tidskriftsartikel (refereegranskat)abstract
- Portal hypertension was induced in rats by partial ligation of the hepatic branches of the portal vein. After 5 days of hypertension the portal veins were taken out and mounted for isometric and quick-release experiments. Portal veins from sham-operated normal rats served as controls. The ligated veins had an increased cross-sectional area, indicating smooth-muscle hypertrophy. Although the absolute magnitude of active force of these veins was increased, the active force per cross-sectional area was decreased, indicating an alteration in the properties of the contractile system. No difference in the Ca2+ concentration-response relations to K+-activated intact control and hypertrophic veins was found. In chemically skinned preparations, devoid of functional plasma membranes, the hypertrophic veins had similar Ca2+ sensitivity (in the presence of I microM calmodulin) but a lower force per cross-sectional area. Force-velocity relations were determined in K+-activated intact preparations. In control veins a reduction in extracellular Ca2+ was associated with a significant reduction in both isometric force and maximal shortening velocity (Vmax). In hypertrophic veins the decreased isometric force at maximal activation was associated with a low Vmax. A comparison between hypertrophic and submaximally stimulated control vessels showed corresponding Vmax and isometric force values. We conclude that the low isometric force of hypertrophic veins is associated with a lower rate of cross-bridge turnover. This could be an effect of alterations in the activation mechanisms or in the intrinsic properties of the contractile system itself.
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| 2. |
- Arner, Anders, et al.
(författare)
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Structural and mechanical adaptations in rat aorta in response to sustained changes in arterial pressure
- 1984
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 122:2, s. 119-126
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Tidskriftsartikel (refereegranskat)abstract
- Structural and mechanical adaptations in response to sustained changes in arterial pressure were studied on abdominal aorta of the male rat. Two models were used: 1. Aortic ligature (L), immediately below the renal arteries producing hypotension distal to the knot (duration before sacrifice 6 weeks or 3 months). 2. One-clip renal hypertensive rats (H) (duration 6 weeks). Normotensive sham-operated rats (C) served as controls. At sacrifice mean tail artery pressure was L: 58 +/- 1, C: 110 +/- 3, and H: 163 +/- 5 mmHg (SE, N=6). Segments of abdominal aorta were mounted in vitro for determination of their length-tension relations (activation: High-K+ solution with 2.5 mM Ca2+). At end of experiments the vessels were supramaximally stimulated at optimal circumference (1o) for active force (activation: High-K+ solution with 10 mM Ca2+, and 10(-5) M noradrenaline), and then fixated for light and electron microscopy. Passive and active length-tension relations were shifted towards lower and higher circumference values for hypo- and hypertensive vessels, respectively. The 1o values were L: 3.60 +/- 0.13, C: 4.44 +/- 0.19, and H: 4.91 +/- 0.29 mm. The media thickness at 1o was reduced in L: 56.0 +/- 3.3, and increased in H: 81.3 +/- 2.4 compared to C: 73.4 +/- 1.8 micron. Maximal active wall stress was L: 46.6 +/- 9.8, C: 74.2 +/- 7.0, and H: 83.8 +/- 7.7 mN/mm2. Intracellular volume (ICV) in the media was L: 30 +/- 2, C: 45 +/- 3, and H: 44 +/- 1% (n=4 for each).
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| 3. |
- Malmqvist, Ulf, et al.
(författare)
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Contractile properties during development of hypertrophy of the smooth muscle in the rat portal vein
- 1988
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 133:1, s. 49-61
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Tidskriftsartikel (refereegranskat)abstract
- Structural and mechanical alterations during hypertrophy of the rat portal vein were investigated. Growth of the vessel was induced by a partial ligature of the vessel causing an increased transmural pressure. Vessel segments from animals kept with ligature for 1, 3, 5 and 7 days, were compared with vessels from sham-operated animals. Maximal active force and vessel cross-sectional area increased with time in the ligated group. On day 7, force and cross-sectional area at the optimal length, were markedly increased in the ligated group (21.1 +/- 1.0 mN, 0.55 +/- 0.04 mm2, n = 9) compared with the control vessels (11.7 +/- 1.0 mN, 0.30 +/- 0.02 mm2, n = 7). Light and electron microscopy of preparations fixed at optimal length showed that the amount of smooth muscle and the cross-sectional area of cell profiles were almost doubled in the ligated group on day 7, consistent with hypertrophy of the smooth muscle. The force per smooth muscle cell area was similar in the two groups (ligated: 132 +/- 15; control: 145 +/- 16 mN mm-2, n = 4-5). The maximal shortening velocity was significantly lower in the hypertrophied group (ligated: 0.28 +/- 0.02; control: 0.41 +/- 0.01 optimal length s-1, n = 6). In chemically skinned preparations, activated by maximal thiophosphorylation of the myosin light chains, force was higher in the ligated group compared to the controls but no difference in maximal shortening velocity was observed. In conclusion, the increased transmural pressure is associated with a rapid increase in the amount of smooth muscle in the portal vein. The mechanical data show that after 7 days the force generating ability of the contractile system has increased in proportion to the smooth muscle cell mass. The unaltered maximal shortening velocity in the skinned hypertrophied preparations suggests that the kinetic properties of the maximally activated contractile system are unaltered. The decreased maximal shortening velocity in the intact hypertrophied preparations may reflect alterations in the excitation-contraction coupling.
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| 4. |
- Olafsson, Isleifur, et al.
(författare)
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Production, characterization and use of monoclonal antibodies against the major extracellular human cysteine proteinase inhibitors cystatin C and kininogen
- 1988
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 48:6, s. 573-582
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Tidskriftsartikel (refereegranskat)abstract
- Murine monoclonal antibodies against the major cysteine proteinase inhibitors of human biological fluids, cystatin C and kininogen, were produced. The cystatin C antibody, HCC3, with a Ka of 2times107 l/mol, increased the inhibition of papain by cystatin C and was suitable for use in immunoblotting, immunohistochemistry and in the construction of a sensitive sandwich enzyme immunoassay for quantification of cystatin C. It recognized not only free cystatin C but also cystatin C in complexes with cysteine proteinases. The kininogen antibody, HK4, was directed against the third, cysteine proteinase inhibitory domain of the heavy chain of kininogen (Ka=1times107 l/mol), but did not influence the papain inhibitory activity of kininogen. It reacted with free kininogen as well as kininogen in complex with cysteine proteinases. Both antibodies could be used for the production of specific immunosorbents.
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| 5. |
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| 6. |
- Abrahamson, Magnus
(författare)
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Human cysteine proteinase inhibitors. Isolation, physiological importance, inhibitory mechanism, gene structure and relation to hereditary cerebral hemorrhage
- 1988
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Ingår i: Scandinavian journal of clinical and laboratory investigation. Supplementum. - 0085-591X. ; 48, s. 21-31
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Tidskriftsartikel (refereegranskat)abstract
- The isolation and characterization of six human cysteine proteinase inhibitors is reported. Their distribution in human biological fluids is also described and discussed with respect to physiological function. Studies on kininogen and cystatin C with respect to structure-function relationships and, as a result of the cystatin C studies, a general model for the mechanism of cysteine proteinase inhibition by cystatins are presented. The model was used for the construction of synthetic inhibitors which showed good inhibitory properties against papain and the streptococcal cysteine proteinase. Structures of cDNA and gene for normal human cystatin C are accounted for, as well as studies on the cystatin C gene in patients suffering from hereditary cystatin C amyloid angiopathy (HCCAA). As a result of this an RFLP that showed total co-segregation with the disease was found. It was concluded that the disease is caused by a point mutation in the cystatin C structural gene and that the RFLP will be a most useful tool for diagnosis of HCCAA. The production of recombinant cystatin C in E. coli is also reported and its possible use for treatment of HCCAA is discussed.
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| 7. |
- Abrahamson, Magnus, et al.
(författare)
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Identification of the probable inhibitory reactive sites of the cysteine proteinase inhibitors human cystatin C and chicken cystatin
- 1987
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 262:20, s. 9688-9694
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Tidskriftsartikel (refereegranskat)abstract
- When an excess of human cystatin C or chicken cystatin was mixed with papain, an enzyme-inhibitor complex was formed immediately. The residual free cystatin was then progressively converted to a form with different electrophoretic mobility and chromatographic properties. The modified cystatins were isolated and sequenced, showing that there had been cleavage of a single peptide bond in each molecule: Gly11-Gly12 in cystatin C, and Gly9-Ala10 in chicken cystatin. The residues Gly11 (cystatin C) and Gly9 (chicken cystatin) are among only three residues conserved in all known sequences of inhibitory cystatins. The modified cystatins were at least 1000-fold weaker inhibitors of papain than the native cystatins. An 18-residue synthetic peptide corresponding to residues 4-21 of cystatin C did not inhibit papain but was cleaved at the same Gly-Gly bond as cystatin C. When iodoacetate or L-3-carboxy- trans-2,3-epoxypropionyl-leucylamido-(4-guanidin o)butane was added to the mixtures of either cystatin with papain, modification of the excess cystatin was blocked. Papain-cystatin complexes were stable to prolonged incubation, even in the presence of excess papain. We conclude that the peptidyl bond of the conserved glycine residue in human cystatin C and chicken cystatin probably is part of a substrate- like inhibitory reactive site of these cysteine proteinase inhibitors of the cystatin superfamily and that this may be true also for other inhibitors of this superfamily. We also propose that human cystatin C and chicken cystatin, and probably other cystatins as well, inhibit cysteine proteinases by the simultaneous interactions with such proteinases of the inhibitory reactive sites and other, so far not identified, areas of the cystatins. The cleavage of the inhibitory reactive site glycyl bond in mixtures of papain with excess quantities of cystatins is apparently due to the activity of a small percentage of atypical cysteine proteinase molecules in the papain preparation that form only very loose complexes with cystatins under the conditions employed and degrade the free cystatin molecules.
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| 8. |
- Abrahamson, Magnus, et al.
(författare)
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Isolation of six cysteine proteinase inhibitors from human urine. Their physicochemical and enzyme kinetic properties and concentrations in biological fluids
- 1986
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 261:24, s. 11282-11289
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Tidskriftsartikel (refereegranskat)abstract
- Six cysteine proteinase inhibitors were isolated from human urine by affinity chromatography on insolubilized carboxymethylpapain followed by ion-exchange chromatography and immunosorption. Physicochemical and immunochemical measurements identified one as cystatin A, one as cystatin B, one as cystatin C, one as cystatin S, and one as low molecular weight kininogen. The sixth inhibitor displayed immunochemical cross-reactivity with salivary cystatin S but had a different pI (6.85 versus 4.68) and a different (blocked) N-terminal amino acid. This inhibitor was tentatively designated cystatin SU. The isolated inhibitors accounted for nearly all of the cysteine proteinase inhibitory activity of the urinary pool used as starting material. The enzyme inhibitory properties of the inhibitors were investigated by measuring inhibition and rate constants for their interactions with papain and human cathepsin B. Antisera raised against the inhibitors were used in immunochemical determinations of their concentrations in several biological fluids. The combined enzyme kinetic and concentration data showed that several of the inhibitors have the capacity to play physiologically important roles as cysteine proteinase inhibitors in many biological fluids. Cystatin C had the highest molar concentration of the inhibitors in seminal plasma, cerebrospinal fluid, and milk; cystatin S in saliva and tears; and kininogen in blood plasma, synovial fluid, and amniotic fluid.
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| 9. |
- Agardh, Carl-David, et al.
(författare)
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Plasma high density lipoproteins and lipolytic enzyme activities in diabetic patients
- 1983
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Ingår i: Acta Medica Scandinavica. - 0001-6101. ; 213:2, s. 123-128
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Tidskriftsartikel (refereegranskat)abstract
- Eighty diabetic patients, consecutively selected from an out-patient clinic, were studied with regard to plasma lipoprotein levels, especially HDL. Patients treated with sulphonylureas had 24% lower HDL cholesterol concentrations (p less than 0.01) but only about 7% lower apo AI levels (n.s.) than those on insulin treatment. This difference could at least partly be explained by differences in age and type of diabetes. There was no relationship between the degree of diabetic control, as measured by fasting blood glucose levels, and HDL levels. In two subgroups of insulin-treated diabetics, selected to represent extremely low and high HDL levels (range 0.5-0.8 and 1.8-2.0 mmol/l, respectively) but matched with regard to age, duration of diabetes, insulin dosage and diabetic control, the activities of lipoprotein lipase and hepatic lipase in postheparin plasma were also recorded. The high HDL group had significantly higher lipoprotein lipase activities (p less than 0.01) and significantly lower hepatic lipase activities (p less than 0.05) than the low HDL group, supporting the hypothetical roles of these enzymes in HDL metabolism, and offering a tentative mechanism behind the large variability of HDL levels in diabetics.
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| 10. |
- Agardh, Carl-David, et al.
(författare)
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Plasma lipids and plasma lipoproteins in diabetics with and without proliferative retinopathy
- 1988
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Ingår i: Acta Medica Scandinavica. - 0001-6101. ; 223:2, s. 165-169
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Tidskriftsartikel (refereegranskat)abstract
- The single most important factor related to the development of diabetic retinopathy is the duration of diabetes. Little is known about the underlying mechanisms, but many factors have been suggested to be involved, among them derangements in plasma lipids and plasma lipoproteins. In the present study we examined the relation between plasma lipids, plasma lipoproteins, and the duration of diabetes in Type I diabetics with and without proliferative retinopathy. The duration of diabetes in the two groups was 12.2 +/- 2.8 and 21.5 +/- 9.0 years, respectively (mean +/- SD; p less than 0.01). Except for moderately low HDL levels, plasma lipid and lipoprotein concentrations were normal in both groups of patients. The levels of lipids and lipoproteins did not correlate with the duration of diabetes. Furthermore, no differences were seen between patients with and without proliferative retinopathy. Thus, the present study does not indicate that plasma lipids and plasma lipoproteins play any major role in the development of diabetic proliferative retinopathy.
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