| 1. |
- Andersson, Irene, 1978, et al.
(author)
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Endothelial dysfunction in growth hormone transgenic mice
- 2006
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In: Clinical Science. - 0143-5221 .- 1470-8736. ; 110:2, s. 217-25
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Journal article (peer-reviewed)abstract
- Acromegaly [overproduction of GH (growth hormone)] is associated with cardiovascular disease. Transgenic mice overexpressing bGH (bovine GH) develop hypertension and hypercholesterolaemia and could be a model for cardiovascular disease in acromegaly. The aims of the present study were to investigate the effects of excess GH on vascular function and to test whether oxidative stress affects endothelial function in bGH transgenic mice. We studied the ACh (acetylcholine)-induced relaxation response in aortic and carotid rings of young (9-11 weeks) and aged (22-24 weeks) female bGH transgenic mice and littermate control mice, without and with the addition of a free radical scavenger {MnTBAP [Mn(III)tetrakis(4-benzoic acid)porphyrin chloride]}. We also measured mRNA levels of eNOS (endothelial nitric oxide synthase) and EC-SOD (extracellular superoxide dismutase). Intracellular superoxide anion production in the vascular wall was estimated using a dihydroethidium probe. Carotid arteries from bGH transgenic mice had an impaired ACh-induced relaxation response (young, 46 +/- 7% compared with 69 +/- 8%; aged, 52 +/- 5% compared with 80 +/- 3%; P < 0.05), whereas endothelial function in aorta was intact in young but impaired in aged bGH transgenic mice. Endothelial dysfunction was corrected by addition of MnTBAP in carotid arteries from young mice and in aortas from aged mice; however, MnTBAP did not correct endothelial dysfunction in carotid arteries from aged bGH transgenic mice. There was no difference in intracellular superoxide anion production between bGH transgenic mice and control mice, whereas mRNA expression of EC-SOD and eNOS was increased in aortas from young bGH transgenic mice compared with control mice (P < 0.05). We interpret these data to suggest that bGH overexpression is associated with a time- and vessel-specific deterioration in endothelial function, initially caused by increased oxidative stress and later by other alterations in vascular function.
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| 2. |
- Annerén, Cecilia, 1972-
(author)
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Tyrosine kinase signalling in embryonic stem cells
- 2008
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In: Clinical Science. - 0143-5221 .- 1470-8736. ; 115:1-2, s. 43-55
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Research review (peer-reviewed)abstract
- Pluripotent ES (embryonic stem) cells can be expanded in culture and induced to differentiate into a wide range of cell types. Self-renewal of ES cells involves proliferation with concomitant suppression of differentiation. Some critical and conserved pathways regulating self-renewal in both human and mouse ES cells have been identified, but there is also evidence suggesting significant species differences. Cytoplasmic and receptor tyrosine kinases play important roles in proliferation, survival, self-renewal and differentiation in stem, progenitor and adult cells. The present review focuses on the role of tyrosine kinase signalling for maintenance of the undifferentiated state, proliferation, survival and early differentiation of ES cells.
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| 3. |
- Berndtson, Dan, et al.
(author)
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Hypovolaemia after glucose/insulin infusions in volunteers
- 2008
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In: Clinical Science. - : Portland Press. - 0143-5221 .- 1470-8736. ; 115:12, s. 371-378
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Journal article (peer-reviewed)abstract
- High-dose intravenous infusion of 5% glucose promotes rebound hypoglycaemia and hypovolaemia in healthy volunteers. To study whether such effects occur in response to glucose/insulin, 12 healthy firemen (mean age, 39 years) received three infusions over 1-2 h that contained 20 ml of 2.5% glucose/kg of body weight, 5 ml of 10% glucose/kg of body weight with 0.05 unit of rapid-acting insulin/kg of body weight, and 4 ml of 50% glucose/kg of body weight with 1 unit of insulin/kg of body weight. The plasma glucose concentration and plasma dilution were compared at 5-10 min intervals over 4 h. Regardless of the amount of administered fluid and whether insulin was given, the plasma glucose concentration decreased to hypoglycaemic levels within 30 min of the infusion ending. The plasma dilution closely mirrored plasma glucose and became negative by approx. 5%, which indicates a reduction in the plasma volume. These alterations were only partially restored during the follow-up period. A linear relationship between plasma glucose and plasma dilution was most apparent when the infused glucose had been dissolved in only a small amount of fluid. For the strongest glucose/insulin solution, this linear relationship had a correlation coefficient of 0.77 (n=386, P<0.0001). The findings of the present study indicate that a redistribution of water due to the osmotic strength of the glucose is the chief mechanism accounting for the hypovolaemia. It is concluded that infusions of 2.5%, 10% and 50% glucose, with and without insulin, in well-trained men were consistently followed by long-standing hypoglycaemia and also by hypovolaemia, which averaged 5%. These results emphasize the relationship between metabolism and fluid balance.
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| 4. |
- Edvinsson, Lars, et al.
(author)
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Triptan-induced contractile (5-HT1B receptor) responses in human cerebral and coronary arteries: relationship to clinical effect
- 2005
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In: Clinical Science. - 1470-8736. ; 109:3, s. 335-342
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Journal article (peer-reviewed)abstract
- Triptans are agonists at 5-HT1B and 5-HT1D (where 5-HT is 5-hydroxytryptamine; serotonin) receptors and cause vasoconstriction of isolated blood vessels. The aim of the present study was to determine vasoconstrictor potency (EC50) of triptans in human coronary and cerebral arteries and to examine whether there was any relationship with the maximal plasma concentrations (Cmax; nM) of the drugs achieved following oral administration of clinically relevant doses to man using values reported in the literature. We also examined the expression of 5-HT1B receptors in atherosclerotic and normal coronary arteries. The vasocontractile responses to sumatriptan, rizatriptan or eletriptan were characterized by in vitro pharmacology. The ratio of Cmax/EC50 was calculated. 5-HT1B and 5-HT1D receptors were visualized by immunohistochemical techniques in coronary arteries. Sumatriptan, rizatriptan and eletriptan were powerful vasoconstrictors in cerebral artery. The rank order of agonist potency was eletriptan = rizatriptan = sumatriptan. In the coronary artery, the triptans were weaker vasoconstrictors. The rank order of potency was similar. In cerebral artery the ratio of Cmax/EC50 was not significantly different from unity, indicating a relationship between these two parameters. In general for the coronary artery, the ratios were significantly less than unity, indicating no direct relationship. Immunohistochemistry showed expression of 5-HT1B receptors in the medial layer, but did not reveal any obvious difference in 5-HT1B receptor expression between normal and atherosclerotic coronary arteries. The results support the notion that triptans are selective vasoconstrictors of cerebral arteries over coronary arteries and that there is a relationship between vasoconstrictor potency in cerebral arteries and clinically relevant plasma levels.
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| 5. |
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| 6. |
- Forte, Amalia, et al.
(author)
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Injury to rat carotid arteries causes time-dependent changes in gene expression in contralateral uninjured arteries
- 2009
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In: Clinical Science. - 1470-8736. ; 116:1-2, s. 125-136
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Journal article (peer-reviewed)abstract
- Vascular surgery aimed at stenosis removal induces local reactions often leading to restenosis. Although extensive analysis has been focused on pathways activated in injured arteries, little attention has been devoted to associated systemic vascular reactions. The aim of the present study was to analyse changes occurring in contralateral uninjured rat carotid arteries in the acute phase following unilateral injury. WKY (Wistar-Kyoto) rats were subjected to unilateral carotid arteriotomy. Contralateral uninjured carotid arteries were harvested from 4 h to 7 days after injury. Carotid arteries were also harvested from sham-operated rats and uninjured rats. Carotid morphology and morphometry were examined. Affymetrix microarrays were used for differential analysis of gene expression. A subset of data was validated by real-time RT-PCR (reverse transcription-PCR) and verified at the protein level by Western blotting. A total of 1011 genes were differentially regulated in contralateral uninjured carotid arteries from 4 h to 7 days after arteriotomy (P < 0.0001; fold change, >= 2) and were classified into 19 gene ontology functional categories. To a lesser extent, mRNA variations also occurred in carotid arteries of sham-operated rats. Among the changes, up-regulation of members of the RAS (renin-angiotensin system) was detected, with possible implications for vasocompensative mechanisms induced by arteriotomy. In particular, a selective increase in the 69 kDa isoform of the N-domain of ACE (angiotensin-converting enzyme), and not the classical somatic 195 kDa isoform, was observed in contralateral uninjured carotid arteries, suggesting that this 69 kDa isoenzyme could influence local Angll (angiotensin II) production. In conclusion, systemic reactions to injury occur in the vasculature, with potential clinical relevance, and suggest that caution is needed in the choice of controls during experimental design in vivo.
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| 7. |
- Gidlöf, Andreas C., et al.
(author)
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Vitamin A : a drug for prevention of restenosis/reocclusion after percutaneous coronary intervention?
- 2008
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In: Clinical Science. - 0143-5221 .- 1470-8736. ; 114:1, s. 19-25
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Research review (peer-reviewed)abstract
- The re-establishment of adequate blood flow in a vessel with a reduced lumen due to an atherosclerotic plaque by percutaneous vascular intervention is a well established procedure. However, the long-term outcome of such interventions is negatively influenced by the development of intimal hyperplasia/restenosis. Although extensively researched, this still represents a significant clinical problem. Retinoids, i.e. natural and synthetic derivates of vitamin A, represent a potential therapeutic compound, since they have been shown to influence the vast majority of processes that ultimately lead to reocclusion of the injured vessel. Retinoids exert their effects at the transcriptional level through their nuclear receptors. Targeting multiple processes, i.e. proliferation, migration, extracellular matrix composition and cell differentiation, as well as coagulation/fibrinolysis, should increase their future role in the prevention of restenosis. The purpose of this review is to summarize the diverse effects of retinoids on pathobiological and biological processes activated at sites of vascular injury with particular emphasis on intimal hyperplasia/restenosis after endovascular interventions.
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| 8. |
- Guldstrand, MC, et al.
(author)
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High-fat diets: healthy or unhealthy?
- 2007
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In: Clinical science (London, England : 1979). - 1470-8736. ; 113:9-1010, s. 397-399
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Journal article (peer-reviewed)
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| 9. |
- Hedin, Annika, et al.
(author)
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Volume expansion and plasma protein clearance during intravenous infusion of 5% albumin and autologous plasma
- 2005
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In: Clinical Science. - : Portland Press. - 0143-5221 .- 1470-8736. ; 108:3, s. 217-224
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Journal article (peer-reviewed)abstract
- Autologous plasma may be used to replace plasma volume and plasma proteins during surgery, but its effectiveness is largely unknown. In the present study, the characteristics of predonated frozen and thawed autologous plasma were compared with those of 5% albumin in 15 male volunteers who received 10 ml/kg of body weight of these colloids as intravenous infusions over 30 min. Venous blood was sampled and urine was collected over 8 h to outline the volume expansion and blood-interstitial fluid space transport of three plasma proteins (albumin, fibrinogen and antithrombin) by means of mass balance analysis. The maximum plasma dilution of 5% albumin and autologous plasma averaged 17 and 21% respectively, and their half-lives were 2.5 and 2.9 h respectively (P<0.03). The between-subject variability in dilution was most pronounced for autologous plasma. Transport of protein from blood to the interstitial space occurred faster when the infused fluid contained the protein in question. The rate was highest at 60 min, and the process was still in progress at 8 h when approx. 60% of the infused albumin, 45% of the fibrinogen and 75% of the infused antithrombin had been translocated to the interstitial fluid space. In contrast with the proteins, excess plasma water was removed by urinary excretion. It is concluded that the volume expansion is equivalent for the two colloid fluids, although it is more predictable for 5% albumin. The transport of protein outlasted the volume expansion.
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| 10. |
- Huang, Zhen, et al.
(author)
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Gender-specific regulation of pancreatic islet blood flow, insulin levels and glycaemia in spontaneously diabetic Goto-Kakizaki rats
- 2008
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In: Clinical Science. - : Portland Press. - 0143-5221 .- 1470-8736. ; 115:1, s. 35-42
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Journal article (peer-reviewed)abstract
- Patients with diabetes are often treated with a statin for hyperlipidaemia and an ACE (angiotensin-converting enzyme) inhibitor or angiotensin receptor antagonist for hypertension or albuminuria. These drugs may also exert beneficial metabolic effects, causing improved glucose tolerance in patients. Gender-related differences have also been observed in the clinical responsiveness to these drugs, but the mechanism behind this is unclear. In the present study, we have investigated whether these drugs and the fatty acid palmitate influence the pancreatic microcirculation, thereby having an impact on insulin secretion and glycaemia in vivo, in spontaneously diabetic male and female Goto-Kakizaki rats. In male rats, pancreatic IBF (islet blood flow) and total PBF (pancreatic blood flow) were increased significantly by pravastatin, captopril and irbesartan. Serum insulin levels were increased by pravastatin and captopril. Palmitate suppressed pancreatic IBF and increased blood glucose. In female animals, pancreatic IBF was stimulated by captopril, candesartan and irbesartan. Total PBF was increased by captopril, candesartan and irbesartan, and by pravastatin. Palmitate suppressed pancreatic IBF and serum insulin secretion. In conclusion, the present study lends support to the view that a local pancreatic RAS (renin-angiotensin system) and pravastatin may be selectively influencing the pancreatic microcirculation and therefore affecting insulin secretion and glycaemia. NEFAs (non-esterified fatty acids) impaired pancreatic IBF, suppressed insulin secretion and increased blood glucose. Substantial gender-related differences in the vascular and metabolic responses to these drugs prevail in this animal model of diabetes.
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