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Donald D Heistad

Publications and source records attributed to Donald D Heistad.

At least 37 records · Page 2Linked to original sources
PubMed2005

Spontaneous stroke in a genetic model of hypertension in mice.

BACKGROUND AND PURPOSE: Hypertension is the most common risk factor for hemorrhagic stroke. An experimental model of stroke, the stroke-prone spontaneously hypertensive rat (SHRSP), which has been enormously useful in studies of cerebral circulation, has been used in >1000 papers. However, SHRSP usually have an ischemic or less commonly hemorrhagic stroke in the cortex, not in the brain stem, cerebellum, or basal ganglia, as in patients with hypertension. The goal of this study was to develop a model of hemorrhagic stroke in hypertensive mice. METHODS: A genetic model of hypertensive mice, double transgenic mice (R+/A+) that overexpress both human renin (R+) and human angiotensinogen (A+), and nonhypertensive control mice were divided into 3 groups: (1) high-salt diet; (2) Nomega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthases, in drinking water; and (3) high-salt diet and L-NAME. RESULTS: All R+/A+ mice on high-salt diet and L-NAME died within 10 weeks, with hemorrhage in the brain stem, and several of the mice had hemorrhages in brain stem, cerebellum, and basal ganglia. No control mice on high-salt diet and L-NAME had hemorrhagic stroke. Arterial pressure in R+/A+ mice increased progressively during high-salt diet and L-NAME. In R+/A+ and control mice, high-salt diet or L-NAME alone did not increase arterial pressure. CONCLUSIONS: We now describe the first model of spontaneous hemorrhagic strokes in hypertensive mice. The type and locations of stroke are reasonably similar to those observed in patients with hypertension.

Angiotensinogen↗
PubMed2004

Gene transfer of extracellular superoxide dismutase failed to prevent cerebral vasospasm after experimental subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: We examined the therapeutic effect of human extracellular superoxide dismutase (ECSOD) gene transfer in the prevention of delayed cerebral vasospasm after experimental subarachnoid hemorrhage (SAH) because it was reported ECSOD relieved early-stage vasospasm. METHODS: Twenty mongrel dogs were divided randomly into 4 groups to serve as control, SAH, SAH+adenovirus ECSOD (AdECSOD), and SAH+no transgene (AdBglII) groups, respectively. An established canine double-hemorrhage model of SAH was used by injecting autologous arterial blood into the cisterna magna on day 0 and day 2. Angiography was performed at day 0 and day 7. Clinical behavior, cerebrospinal fluid (CSF) ECSOD activity, CSF leukocyte count, morphology, and human ECSOD expression (RT-PCR) in the basilar arteries were evaluated. RESULTS: Severe vasospasm was obtained in SAH, SAH+AdECSOD, and SAH+AdBglII gene-transferred dogs, and the residual diameters of the basilar artery were 41+/-1%, 39+/-4%, and 49+/-4%, respectively. Increased CSF activity of ECSOD was obtained in SAH+AdECSOD (162+/-23 U/mL) when compared with SAH (26+/-2) and SAH+AdBglII (25+/-3) dogs. RT-PCR confirmed successful gene transfer in the basilar arteries from SAH+AdECSOD dogs. Increased leukocyte counts were observed in the CSF and in the subarachnoid space, especially in SAH+AdECSOD and SAH+AdBglII dogs. CONCLUSIONS: Gene transfer of human ECSOD failed to prevent delayed cerebral vasospasm.

Adenoviridae↗
PubMed2004

Neuronal expression and regulation of CGRP promoter activity following viral gene transfer into cultured trigeminal ganglia neurons.

We have examined the regulation of calcitonin gene-related peptide (CGRP) promoter activity in primary cultures of rat trigeminal ganglia neurons. A viral vector was used to circumvent the potential complication of examining only a small subpopulation of cells in the heterogeneous cultures. Infection with high titers of recombinant adenovirus containing 1.25 kb of the rat CGRP promoter linked to the beta-galactosidase reporter gene (AdCGRP-lacZ) yielded expression in about 50% of the CGRP-expressing neurons. The CGRP-lacZ reporter gene was preferentially expressed in neurons, with 91% co-expression with endogenous CGRP. In contrast, an adenoviral vector containing a CMV-lacZ reporter was predominantly expressed in non-neuronal cells, with only 29% co-expression with CGRP. We then asked whether the CGRP promoter in the viral vector could be regulated by serotonin receptor type 1 (5-HT(1)) agonists. Promoter activity was decreased two- to threefold by treatment with five 5-HT(1B/D) agonists, including the triptan drugs sumatriptan, eletriptan, and rizatriptan that are used for migraine treatment. As controls, CMV promoter activity was not affected, and 5-HT(1B/D) receptor antagonists blocked the repression caused by sumatriptan and eletriptan. Thus, adenoviral gene transfer can be used in trigeminal ganglia neurons for studying the mechanisms of triptan drug action on CGRP synthesis.

Adenoviridae↗
PubMed2004

Gene transfer of extracellular superoxide dismutase improves relaxation of aorta after treatment with endotoxin.

Lipopolysaccharide (LPS) impairs vascular function, in part by generation of reactive oxygen species. One goal of this study was to determine whether gene transfer of extracellular SOD (ECSOD) improves vascular responsiveness in LPS-treated rats. A second goal was to determine whether effects of ECSOD are dependent on the heparin-binding domain of the enzyme, which facilitates binding of ECSOD to the outside of cells. Adenoviruses containing ECSOD (AdECSOD), ECSOD with deletion of its heparin-binding domain (AdECSOD-HBD), or a control virus (AdLacZ) were injected intravenously into rats. Three days later, vehicle or LPS (10 mg/kg ip) was injected. After 24 h, vascular reactivity was examined in aortic rings in vitro. Maximum relaxation to acetylcholine was 95 +/- 1% (means +/- SE) after AdlacZ plus vehicle and 77 +/- 3% after AdlacZ plus LPS (P < 0.05). Responses to calcium ionophore A-23187 and submaximal concentrations of nitroprusside also were impaired by LPS. Gene transfer of ECSOD, but not AdECSOD-HBD, improved (P < 0.05) relaxation to acetylcholine and A-23187 after LPS. Maximum relaxation to acetylcholine was 88 +/- 3% after LPS plus AdECSOD. Superoxide was increased in aorta after LPS, and the levels were reduced after AdECSOD but not AdECSOD-HBD. LPS-induced adhesion of leukocytes to aortic endothelium was reduced by AdECSOD but not by AdECSOD-HBD. We conclude that after gene transfer in vivo, binding of ECSOD to arteries effectively decreases the numbers of adherent leukocytes and levels of superoxide and improves impaired endothelium-dependent relaxation produced by LPS.

Adenoviridae↗
PubMed2004

Vasomotor responses in MnSOD-deficient mice.

MnSOD is the only mammalian isoform of SOD that is necessary for life. MnSOD(-/-) mice die soon after birth, and MnSOD(+/-) mice are more susceptible to oxidative stress than wild-type (WT) mice. In this study, we examined vasomotor function responses in aortas of MnSOD(+/-) mice under normal conditions and during oxidative stress. Under normal conditions, contractions to serotonin (5-HT) and prostaglandin F2alpha (PGF2alpha), relaxation to ACh, and superoxide levels were similar in aortas of WT and MnSOD(+/-) mice. The mitochondrial inhibitor antimycin A reduced contraction to PGF2alpha and impaired relaxation to ACh to a similar extent in aortas of WT and MnSOD(+/-) mice. The Cu/ZnSOD and extracellular SOD inhibitor diethyldithiocarbamate (DDC) paradoxically enhanced contraction to 5-HT and superoxide more in aortas of WT mice than in MnSOD(+/-) mice. DDC impaired relaxation to ACh and reduced total SOD activity similarly in aortas of both genotypes. Tiron, a scavenger of superoxide, normalized contraction to 5-HT, relaxation to ACh, and superoxide levels in DDC-treated aortas of WT and MnSOD(+/-) mice. Hypoxia, which reportedly increases superoxide, reduced contractions to 5-HT and PGF2alpha similarly in aortas of WT and MnSOD(+/-) mice. The vasomotor response to acute hypoxia was similar in both genotypes. In summary, under normal conditions and during acute oxidative stress, vasomotor function is similar in WT and MnSOD(+/-) mice. We speculate that decreased mitochondrial superoxide production may preserve nitric oxide bioavailability during oxidative stress.

Animals↗
PubMed2003

Gene-targeted mice reveal a critical role for inducible nitric oxide synthase in vascular dysfunction during diabetes.

BACKGROUND AND PURPOSE: Inducible nitric oxide synthase (iNOS) is a mediator of vascular dysfunction during inflammation. The purpose of this study was to test the hypothesis that vascular dysfunction during diabetes is dependent on expression of iNOS. METHODS: Diabetes was produced in mice with streptozotocin (150 mg/kg IP). After 4 to 6 months of diabetes, vasomotor function was examined in vitro in carotid arteries from mice with targeted disruption of the gene for iNOS (iNOS-deficient mice) and from normal, wild-type (WT) mice. RESULTS: Contractile responses of carotid arteries to U46619, a thromboxane A2 analogue, were not altered by diabetes in WT mice. Responses to U46619 were increased in arteries from diabetic iNOS-deficient mice compared with diabetic WT and nondiabetic mice (iNOS-deficient and WT mice). These results indicate that expression of iNOS inhibits an increased vasoconstrictor response during diabetes. Arteries from nondiabetic WT mice relaxed 83+/-2% (mean+/-SE) in response to acetylcholine (1 micromol/L) compared with 58+/-6% in arteries from diabetic WT mice (P<0.05 versus nondiabetic mice). In contrast, relaxation of carotid arteries to acetylcholine was similar (81+/-4% versus 76+/-6%; P>0.05) in iNOS-deficient mice under nondiabetic and diabetic conditions, respectively. Thus, diabetes produced impairment of endothelium-dependent relaxation in arteries from WT but not iNOS-deficient mice. Endothelium-independent relaxation in response to nitroprusside was similar in arteries from all mice. CONCLUSIONS: These results provide the first direct evidence that impairment of endothelium-dependent relaxation during diabetes is dependent on expression of iNOS.

Animals↗
PubMed2003

Endothelin-1 stimulates arterial VCAM-1 expression via NADPH oxidase-derived superoxide in mineralocorticoid hypertension.

Although hypertension is a major risk factor for atherosclerosis, its underlying mechanisms remain to be delineated. We have recently reported that both endothelin-1 (ET-1) and vascular cellular adhesion molecule-1 (VCAM-1) levels, key early markers of atherosclerosis, are significantly elevated in carotid arteries of deoxycorticosterone acetate (DOCA)-salt hypertensive rats, a model known for its suppressed plasma renin levels. This study tested the hypothesis that ET-1 augments arterial VCAM-1 expression through NADPH oxidase-derived superoxide (O2-). Carotid arteries of DOCA-salt or sham-operated rats were transduced ex vivo with extracellular superoxide dismutase (EC-SOD), dominant negative HA-tagged N17Rac1 that inhibits Rac1, the small GTPase component of NADPH oxidase, or beta-galactosidase (beta-gal) reporter gene (5x10(10) plaque formation units [pfu]/mL), and the effect of transgene expression on O2- and VCAM-1 levels was assayed 24 hours afterward. The arterial activity of NADPH oxidase but not xanthine oxidase was significantly higher in DOCA-salt than in sham rats, which was abolished by the selective ETA receptor antagonist ABT-627 (3x10(-8) mol/L), NADPH oxidase inhibitor apocynin (10(-4) mol/L), or dominant negative Rac1 gene transfer. The levels of O2- and VCAM-1 were significantly increased in arteries of DOCA-salt rats, an effect that was ameliorated after EC-SOD or dominant negative Rac1 but not beta-gal reporter gene transfer. ABT-627 and apocynin also significantly reduced elevated VCAM-1 levels in ET-1-treated arteries of normal rats and arteries of DOCA-salt rats. The results of this study indicate that ET-1 stimulates arterial VCAM-1 expression by producing O2- from an ETA receptor/NADPH oxidase pathway in low-renin mineralocorticoid hypertension.

Animals↗
PubMed2003

Gene transfer of extracellular superoxide dismutase reduces arterial pressure in spontaneously hypertensive rats: role of heparin-binding domain.

Oxidative stress may contribute to hypertension. The goals of this study were to determine whether extracellular superoxide dismutase (ECSOD) reduces arterial pressure in spontaneously hypertensive rats (SHR) and whether its heparin-binding domain (HBD), which is responsible for cellular binding, is necessary for the function of ECSOD. Three days after intravenous injection of an adenoviral vector expressing human ECSOD (AdECSOD), mean arterial pressure (MAP) decreased from 165+/-4 mm Hg (mean+/-SE, n=7) to 124+/-3 mm Hg (n=7) in adult anesthetized SHR (P<0.01) but was not altered in normotensive Wistar-Kyoto rats. Cardiac output was not changed in SHR 3 days after AdECSOD. Gene transfer of ECSOD with deletion of the HBD (AdECSODDeltaHBD) had no effect on SHR MAP, even though plasma SOD activity was greater after AdECSODDeltaHBD than after AdECSOD. Immunohistochemistry revealed intense staining for ECSOD in blood vessels and kidneys after AdECSOD but not after AdECSODDeltaHBD. Impaired relaxation of the carotid artery to acetylcholine in SHR was significantly improved after AdECSOD. Cumulative sodium balance in SHR was reduced by AdECSOD compared with AdECSODDeltaHBD. Gene transfer of ECSOD also reduced MAP in conscious SHR, although the effect was not as profound as in anesthetized SHR. In summary, gene transfer of ECSOD, with a strict requirement for its HBD, reduces systemic vascular resistance and arterial pressure in a genetic model of hypertension. This reduction in arterial pressure may be mediated by vasomotor and/or renal mechanisms.

Adenoviridae↗
PubMed2003

Gene therapy for cerebral vascular disease: update 2003.

Gene therapy is a promising strategy for cerebrovascular diseases. Several genes that encode vasoactive products have been transferred via cerebrospinal fluid for the prevention of vasospasm after subarachnoid hemorrhage. Transfer of neuroprotective genes, including targeting of proinflammatory mediators, is a current strategy of gene therapy for ischemic stroke. Stimulation of growth of collateral vessels, stabilization of atherosclerotic plaques, inhibition of thrombosis, and prevention of restenosis are important objectives of gene therapy for coronary and limb arteries, but application of these approaches to carotid and intracranial arteries has received little attention. Several fundamental advances, including development of safer vectors, are needed before gene therapy achieves an important role in the treatment of cerebrovascular disease and stroke.

Animals↗
PubMed2003

Gene transfer of extracellular superoxide dismutase reduces cerebral vasospasm after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Superoxide may play an important role in cerebral vasospasm after subarachnoid hemorrhage (SAH). Our first goal was to determine the effect of gene transfer of extracellular superoxide dismutase (ECSOD) on vasospasm after experimental SAH. Our second goal was to determine whether tissue binding of ECSOD via the heparin-binding domain (HBD) is important for the effect of the enzyme. Thus, we examined effects of gene transfer of ECSOD with the HBD deleted (ECSODDeltaHBD). METHODS: Adenovirus expressing human ECSOD (AdECSOD), ECSODDeltaHBD (AdECSODDeltaHBD), or no transgene (AdBglII) was injected into the cisterna magna of anesthetized rabbits 30 minutes after induction of experimental SAH. Cerebral angiography, an assay for ECSOD activity in cerebrospinal fluid (CSF), and Western blotting for human ECSOD in the basilar artery were performed. RESULTS: Baseline diameter of the basilar artery averaged 0.77+/-0.01 mm (mean+/-SEM) and was similar in all treatment groups. Decreases in diameter of the basilar artery 2 days after SAH were smaller after AdECSOD (11+/-3%; n=10) than after AdBglII (25+/-4%; n=7; P<0.05). ECSOD activity was not detected in CSF before SAH and gene transfer. Of 8 rabbits treated with AdECSOD, in which ECSOD activity in CSF was measured after SAH, 5 animals had detectable ECSOD activity in CSF (46+/-13 U/mL). In these 5 rabbits, the diameter decreased by only 6+/-3%, and ECSOD protein was detected in the basilar artery. After AdECSODDeltaHBD (n=4), despite high levels of ECSOD activity in CSF (91+/-19 U/mL), vessel diameter decreased by 20+/-2%, and no ECSODDeltaHBD protein was detected in the basilar artery. CONCLUSIONS: Gene transfer of ECSOD reduces cerebral vasospasm after experimental SAH. Tissue binding of the enzyme is essential for cerebral vascular effects of ECSOD.

Adenoviridae↗
PubMed2003

Mikamo Lecture: a radical view on the 'superfamily' of cardiovascular risk factors.

Many risk factors for cardiovascular disease generate superoxide in the blood vessels and thereby impair endothelial function. To emphasize the critical role of oxygen radicals, this is a 'radical view' of those risk factors. It will be useful to organize risk factors into a 'superfamily', with consideration of mediators, mechanisms, and target organs. Studies are summarized which suggest that, in parallel with the impairment of endothelial vasomotor function, the thrombin/thrombomodulin/activated protein C anticoagulant mechanism, which requires endothelial thrombomodulin, is also impaired by atherosclerosis and improves during regression of atherosclerosis. Impairment of the anticoagulant mechanism may contribute to thrombosis in atherosclerotic arteries, and improvement of the anticoagulant mechanism during regression of atherosclerosis may reduce the risk of cardiovascular events.

Arteriosclerosis↗
PubMed2002

Effect of hyperhomocysteinemia on protein C activation and activity.

Hyperhomocysteinemia has been proposed to inhibit the protein C anticoagulant system through 2 mechanisms: decreased generation of activated protein C (APC) by thrombin, and resistance to APC caused by decreased inactivation of factor Va (FVa). We tested the hypotheses that generation of APC by thrombin is impaired in hyperhomocysteinemia in monkeys and that hyperhomocysteinemia produces resistance to APC in monkeys, mice, and humans. In a randomized crossover study, cynomolgus monkeys were fed either a control diet or a hyperhomocysteinemic diet for 4 weeks. Plasma total homocysteine (tHcy) was approximately 2-fold higher when monkeys were on the hyperhomocysteinemic diet than when they were on the control diet (9.8 +/- 2.0 microM versus 5.6 +/- 1.0 microM; P <.05). After infusion of human thrombin (25 microg/kg of body weight), the peak level of plasma APC was 136 +/- 16 U/mL in monkeys fed the control diet and 127 +/- 13 U/mL in monkeys fed the hyperhomocysteinemic diet (P >.05). The activated partial thromboplastin time was prolonged to a similar extent by infusion of thrombin in monkeys fed the control diet and in those fed the hyperhomocysteinemic diet. The sensitivity of plasma FV to human APC was identical in monkeys on control diet and those on hyperhomocysteinemic diet. We also did not detect resistance of plasma FV to APC in hyperhomocysteinemic mice deficient in cystathionine beta-synthase (plasma tHcy, 93 +/- 16 microM) or in human volunteers with acute hyperhomocysteinemia (plasma tHcy, 45 +/- 6 microM). Our findings indicate that activation of protein C by thrombin and inactivation of plasma FVa by APC are not impaired during moderate hyperhomocysteinemia in vivo.

Animals↗
PubMed2002

Anticoagulant responses to thrombin are enhanced during regression of atherosclerosis in monkeys.

BACKGROUND: Diet-induced atherosclerosis in monkeys produces abnormal anticoagulant responses to thrombin, including decreased generation of activated protein C (APC). We tested the hypothesis that anticoagulant responses to thrombin increase toward normal during regression of atherosclerosis. METHODS AND RESULTS: Six cynomolgus monkeys were fed a high-fat atherogenic diet for 44 months and then a low-fat regression diet for 8 months. Serum total cholesterol decreased from 417+/-44 to 68+/-6 mg/dL (mean+/-SEM) and LDL cholesterol decreased from 375+/-44 to 27+/-5 mg/dL after the regression diet. In response to infusion of thrombin, the activated partial thromboplastin time (APTT) increased by 11+/-3 seconds before the regression diet and by 41+/-22 seconds after the regression diet (P=0.01). The peak level of circulating plasma APC was 52+/-9 ng/mL before the regression diet and 88+/-17 ng/mL after the regression diet (P=0.01). The APC sensitivity of plasma factor V was identical before and after the regression diet. Three additional atherosclerotic monkeys that remained on the high-fat diet for 8 months demonstrated no change in APTT or activation of protein C in response to thrombin. CONCLUSIONS: Short-term dietary regression of atherosclerosis produces enhanced anticoagulant responses to thrombin in vivo.

Animals↗
PubMed2002

Quantification of mRNA for endothelial NO synthase in mouse blood vessels by real-time polymerase chain reaction.

The mouse is useful in studies of vascular biology because of its well-defined genetics and because the mouse genome can be manipulated. However, because only small amounts of mRNA can be extracted from blood vessels, the quantification of gene expression in individual mice is difficult. Endothelial NO synthase (eNOS) plays a major role in the regulation of vascular tone and growth. In addition, there appear to be sex differences in the production of NO under basal conditions in mouse aortas. The goals of this study were to develop a real-time polymerase chain reaction (PCR) method to quantify eNOS mRNA in blood vessels from mice and to examine eNOS mRNA levels in vessels from male and female mice. Blood vessels were isolated from C57BL/6 mice. Total RNA from individual mice was isolated and reverse-transcribed. The number of molecules of eNOS mRNA (after reverse transcription) was determined against cDNA standards, with 18S rRNA used as a control for RNA input and reverse-transcription efficiency. When expressed as copy numbers per nanogram of total RNA or as the ratio of eNOS to 18S rRNA, eNOS mRNA was lower in the aortas of female mice than in those of male mice at 7 to 9 months of age. In contrast, no difference in eNOS mRNA was found in the aortas of 2-month-old mice. In addition, eNOS mRNA levels were similar in the carotid, cerebral, and coronary arteries. These findings provide the first quantitative measurements of eNOS mRNA by using real-time PCR in the vessels of mice and suggest age- and sex-related differences in the basal levels of eNOS mRNA in mice. In addition, the eNOS region that was used for real-time PCR was amplified and sequenced for monkeys and other species. With modifications, this region may be used to design real-time PCR for eNOS in other species.

Animals↗
PubMed2002

Regression of atherosclerosis in monkeys reduces vascular superoxide levels.

Superoxide (O2*-) in arteries may contribute to atherosclerosis in part by inactivation of nitric oxide. We hypothesized that regression of atherosclerosis in nonhuman primates is associated with a decrease in vascular NAD(P)H oxidase, decreased O2*- levels, and improved endothelium-dependent relaxation. Cynomolgus monkeys (n=28) were fed an atherogenic diet for 47+/-10 (mean+/-SE) months. In carotid arteries (containing advanced lesions), femoral arteries (moderate lesions), and saphena arteries (minimal lesions), we examined O2*- levels and vasomotor function. Compared with vessels from normal monkeys (n=8), O2*- levels (measured by lucigenin-enhanced chemiluminescence) were 3.3-fold higher in carotid, 1.7-fold higher in femoral, and not different in saphena arteries from atherosclerotic monkeys. Dihydroethidium staining also demonstrated increased O2*- levels throughout the vessel wall in femoral and carotid arteries from atherosclerotic monkeys. Components of the NAD(P)H oxidase (p22(phox) and p47(phox)) were increased in atherosclerotic arteries, and immunohistochemistry demonstrated colocalization primarily to areas of macrophage infiltration. Relaxation to acetylcholine was impaired in carotid and femoral, but not saphena, arteries from atherosclerotic monkeys. After 8 months of regression diet (n=9), serum cholesterol decreased to normal, and O2*- levels (basal and NAD(P)H-stimulated), as well as expression of NAD(P)H oxidase, returned toward normal. Relaxation to acetylcholine improved in femoral arteries, but not in the more diseased carotid arteries. We conclude that, in a primate model of moderately severe atherosclerosis and regression of atherosclerosis, changes in endothelial function are inversely related to O2*- and NAD(P)H oxidase levels. Reduction in vascular O2*- during regression of atherosclerosis may contribute to improvement in vasomotor function.

Acetylcholine↗