Sudanophilic Lesions Research Articles

Patterns of Sudanophilic Lesions at Ostia of Descending Thoracic and Abdominal Aorta in Cholesterol-Fed Adult Rabbits

Las lesiones ateroscleroticas Sudan-positivas se producen preferentemente en los margenes posteriores y laterales del ostio de las ramas arteriales en neonatos humanos y en conejos destetados, pero tienden a desarrollarse en los margenes laterales y superiores en sujetos de edad avanzada. Investigamos el patron de lesiones sudanofilicas en el ostio aortico de conejos adultos alimentados con colesterol y determinamos las diferencias en la distribucion de lesiones entre la aorta toracica descendente y abdominal. Diez conejos machos blancos adultos New Zealand fueron alimentados con una dieta alta en colesterol al 2%. Despues de seis semanas, fueron extraidas las aortas, se disecaron longitudinalmente y se tineron con Sudan-IV para el examen macroscopico y se observaron las lesiones ateroscleroticas. Fueron examinados 156 ostios de aortas toracicas descendentes y 90 de aortas abdominales. Fueron calculadas y comparadas las frecuencias medias de lesiones superiores, inferiores y de los margenes laterales de los ostios afectados. Las lesiones sudanofilicas se detectaron en alrededor del 32% de ostios de la aorta toracica descendente y en el 25% de las aortas abdominales. En el ostio de la aorta toracica descendente, las frecuencias de lesiones fueron significativamente mayores (p 0,05), pero muy significativa al comparar el margen superior con el inferior (p <0,001). Llegamos a la conclusion que en los conejos adultos alimentados con colesterol, el patron juvenil de deposicion de lipidos por inferior persiste en el ostio de la aorta toracica descendente, mientras que se produce un cambio del modelo en los sujetos de mayor edad hacia superior del ostio de la aorta abdominal.

Abstract 5192: G Protein-coupled Receptor Kinase-5 Attenuates Atherosclerosis by Reducing PDGF-induced Smooth Muscle Cell Proliferation and Migration

G protein-coupled receptor kinase-5 (GRK5) is a Ser/Thr kinase that up-regulates in atherosclerotic arteries; it phosphorylates and desensitizes many receptors important to atherogenesis, including heptahelical receptors and the platelet-derived growth factor receptor- β (PDGFR β ). We therefore tested the hypothesis that GRK5 reduces atherogenesis, by comparing atherosclerosis in male C57BL/6-congenic apoe −/− / grk5 −/− and apoe −/− mice, fed a Western diet for 12 wk from age 5 wk, with equivalent serum cholesterols and blood pressures. Aortic atherosclerosis (en face) was 50% greater in grk5 −/− (n=20) than in grk5 +/+ (n=18) mice: Sudanophilic lesions covered 10.6±0.8% versus 7.0±0.5% of aortic area, respectively ( p &lt;0.001). To test whether this difference could result from GRK5-mediated regulation of arterial smooth muscle cells (SMCs) in vivo, we denuded the common carotid endothelium with a 0.36-mm wire in 25-wk-old male B6-congenic WT and grk5 KO mice, using a procedure we previously showed (by bone marrow transplant) produces neointimal hyperplasia comprising SMCs derived only from arterial media. Before injury, GRK5 KO and WT carotids had identical luminal and medial areas. However, 4 wk after injury, neointimal area was 350% greater in GRK5 KO (0.06±0.01 mm 2 ) than in WT mice (0.017±0.007 mm 2 ) (n=5/group, p&lt;0.02), but medial areas were equivalent. Two wk after injury, medial SMCs showed 80±20% greater PDGFR β activation per cell in GRK5 KO than in WT arteries (n=3/group, p&lt;0.02), judged by quantitative immunofluorescence microscopy for PDGFR β -phospho-Tyr 1021 ; total PDGFR β levels were equivalent in KO and WT arteries. In vitro, SMC proliferation evoked by PDGF or 2.5% FBS was greater in GRK5 KO than in WT SMCs (3 lines/genotype, p&lt;0.05), by 80±30% and 33±8%, respectively (assessed by SMC counting). Migration (in modified Boyden chambers) was also greater in GRK5 KO than WT SMCs, by 70±20%, 160±20% and 200±30%, respectively, in response to PDGF, 10% FBS, and activated macrophages (p&lt;0.05), despite equivalent GRK5 KO and WT CD4 + lymphocyte migration. We conclude that GRK5 attenuates atherosclerosis, at least in part, by reducing SMC migration and proliferation evoked through the PDGFR β , and perhaps other SMC receptors activated by macrophages.

PECAM-1 is a critical mediator of atherosclerosis

Atherosclerosis is a chronic inflammatory disease of large arteries in which lesion development preferentially occurs at vessel sites exposed to rapid changes in flow. We have previously shown that platelet endothelial cell adhesion molecule (PECAM-1), a surface receptor of the immunoglobulin superfamily, is involved in mechanosensing of rapid changes in flow. We wondered whether apolipoprotein E deficient (ApoE(-/-)) mice, predisposed to development of atheromas, would be protected from atherosclerosis by deficiency in PECAM-1. Using double knockout (DKO) mice for both PECAM-1 and ApoE (ApoE(-/-)/PECAM-1(-/-)) we found a significant reduction of sudanophilic lesions in their aortae compared to single knockout (SKO) (ApoE(-/-)/PECAM-1(+/+)) mice maintained on a high-fat Western diet. Immunostaining of aortic sinus cross sections demonstrated significantly lower ICAM-1 expression in DKO lesions compared with SKO lesions, and en face preparations of vessel regions subjected to disturbed and laminar flow showed less disruption of junctional connexin 43 in DKO than in SKO mice. Thus, PECAM-1 deficiency reduced the extent of lesions at the aortic arch and the aortic sinus, and lowered atherogenic indices. These results suggest that PECAM-1 is an important factor in the atherogenic changes seen in the ApoE-deficient mouse model and thus should be considered as a potential target for protection against atherosclerosis.

Interleukin-1 plays a major role in vascular inflammation and atherosclerosis in male apolipoprotein E-knockout mice

To examine the role of the balance between interleukin (IL)-1 and IL-1 receptor antagonist (IL-1Ra) in atherosclerosis and vascular inflammation. Transgenic (Tg) mice overexpressing either secreted IL-1Ra or intracellular IL-1Ra1 as well as IL-1Ra-deficient mice (IL-1Ra -/-) were crossed with apolipoprotein E-deficient mice (ApoE -/-). In males fed a cholesterol-rich diet for 10 weeks, average atherosclerotic lesion area within aortic roots was significantly decreased in ApoE -/- secreted IL-1Ra Tg (-47%) and ApoE -/- intracellular IL-1Ra1 Tg (-40%) mice as compared to ApoE -/- non-Tg controls. The extent of sudanophilic lesions was reduced within the thoraco-abdominal aorta in ApoE -/- secreted IL-1Ra (-53%) and ApoE -/- intracellular IL-1Ra1 (-67%) Tg mice. In parallel experiments, we observed early mortality and illness among double deficient mice, whereas ApoE -/- IL-1Ra +/+ and ApoE +/+ IL-1Ra -/- mice were apparently healthy. After 7 weeks of diet, ApoE -/- IL-1Ra -/- mice exhibited massive aortic inflammation with destruction of the vascular architecture, but no signs of atherosclerosis. ApoE -/- IL-1Ra +/+ had atherosclerosis and a moderate inflammatory reaction, whereas ApoE +/+ IL-1Ra -/- mice were free of vascular lesions. Macrophages were present in large amounts within inflammatory lesions in the adventitia of ApoE -/- IL-1Ra -/- mice. Our results demonstrate that the IL-1/IL-1Ra ratio plays a critical role in the pathogenic mechanisms leading to vascular inflammation and atherosclerosis in ApoE -/- mice.

New Method for Imaging Innervation of the Renal Preglomerular Vasculature. Alterations in Hypertensive Rats

To develop a new method for viewing adrenergic innervation along renal preglomerular vessels; to assess nerve densities and vascular lesions along arcuate arteries (ArcA), arcuate arterial branches (ArcB), and interlobular arteries (ILA) in spontaneously hypertensive rats (SHR) and in angiotensin II (AngII) and in N(G)-nitro-L-arginine methyl ester (L-NAME) hypertensive rats. Preglomerular vasculatyres were isolated after HCl maceration and were immunostained against synaptophysin, a membrane protein of synaptic vesicles. Lesions were stained with Sudan black. Longitudinal nerve densities and relative frequencies of ArcA, ArcB, and ILA endowed with sudanophilic lesions were assessed separately. Synaptophysin immunostaining revealed the vascular neural plexus. Nerves were adrenergic, as the plexus was destroyed by treatment with 6-hydroxy dopamine. Vascular lesions were not seen in SHR, and increased nerve density was observed along ArcA and ILA. In L-NAME- and AngII-hypertensive rats, vascular lesions affected predominantly ArcB and ILA, and nerve density was reduced by 12% and 28% (ArcA), 37% and 31% (ArcB), and by 55% and 34% (ILA), respectively, versus normotensive controls. Endothelin-1 receptor blockade did not affect AngII-induced hypertension but prevented both lesion development and reduction of density of the vascular neural plexus. The method we have devised provides a direct en face view of the vascular adrenergic innervation of isolated preglomerular vasculature. Measurements in hypertensive rat models suggest a link between vascular lesions and reduction in nerve density in hypertension. Endothelin-1 likely plays a key role in mediation both vascular injury and altered vascular nerve density in hypertension.

New Method for Imaging Innervation of the Renal Preglomerular Vasculature. Alterations in Hypertensive Rats

Objective: To develop a new method for viewing adrenergic innervation along renal preglomerular vessels; to assess nerve densities and vascular lesions along arcuate arteries (ArcA), arcuate arterial branches (ArcB), and interlobular arteries (ILA) in spontaneously hypertensive rats (SHR) and in angiotensin II (AngII) and in NG-nitro-l-arginine methyl ester (l-NAME) hypertensive rats. Methods: Preglomerular vasculatures were isolated after HCl maceration and were immunostained against synaptophysin, a membrane protein of synaptic vesicles. Lesions were stained with Sudan black. Longitudinal nerve densities and relative frequencies of ArcA, ArcB, and ILA endowed with sudanophilic lesions were assessed separately. Results: Synaptophysin immunostaining revealed the vascular neural plexus. Nerves were adrenergic, as the plexus was destroyed by treatment with 6-hydroxy dopamine. Vascular lesions were not seen in SHR, and increased nerve density was observed along ArcA and ILA. In l-NAME- and AngII-hypertensive rats, vascular lesions affected predominantly ArcB and ILA, and nerve density was reduced by 12% and 28% (ArcA), 37% and 31% (ArcB), and by 55% and 34% (ILA), respectively, versus normotensive controls. Endothelin-1 receptor blockade did not affect AngII-induced hypertension but prevented both lesion development and reduction of density of the vascular neural plexus. Conclusions: The method we have devised provides a direct en face view of the vascular adrenergic innervation of isolated preglomerular vasculature. Measurements in hypertensive rat models suggest a link between vascular lesions and reduction in nerve density in hypertension. Endothelin-1 likely plays a key role in mediating both vascular injury and altered vascular nerve density in hypertension.

New Method for Imaging Innervation of the Renal Preglomerular Vasculature. Alterations in Hypertensive Rats

Objective: To develop a new method for viewing adrenergic innervation along renal preglomerular vessels; to assess nerve densities and vascular lesions along arcuate arteries (ArcA), arcuate arterial branches (ArcB), and interlobular arteries (ILA) in spontaneously hypertensive rats (SHR) and in angiotensin II (AngII) and in NG-nitro-l-arginine methyl ester (l-NAME) hypertensive rats. Methods: Preglomerular vasculatures were isolated after HCl maceration and were immunostained against synaptophysin, a membrane protein of synaptic vesicles. Lesions were stained with Sudan black. Longitudinal nerve densities and relative frequencies of ArcA, ArcB, and ILA endowed with sudanophilic lesions were assessed separately. Results: Synaptophysin immunostaining revealed the vascular neural plexus. Nerves were adrenergic, as the plexus was destroyed by treatment with 6-hydroxy dopamine. Vascular lesions were not seen in SHR, and increased nerve density was observed along ArcA and ILA. In l-NAME- and AngII-hypertensive rats, vascular lesions affected predominantly ArcB and ILA, and nerve density was reduced by 12% and 28% (ArcA), 37% and 31% (ArcB), and by 55% and 34% (ILA), respectively, versus normotensive controls. Endothelin-1 receptor blockade did not affect AngII-induced hypertension but prevented both lesion development and reduction of density of the vascular neural plexus. Conclusions: The method we have devised provides a direct en face view of the vascular adrenergic innervation of isolated preglomerular vasculature. Measurements in hypertensive rat models suggest a link between vascular lesions and reduction in nerve density in hypertension. Endothelin-1 likely plays a key role in mediating both vascular injury and altered vascular nerve density in hypertension.

Vascular endothelin-1 gene expression and synthesis and effect on renal type I collagen synthesis and nephroangiosclerosis during nitric oxide synthase inhibition in rats.

The progression of hypertension during NO deficiency is associated with renal vascular fibrosis due to increased extracellular matrix (mainly collagen I) formation. The purpose of the present study was to investigate whether endothelin-1 (ET-1) is involved in this pathophysiological process. Treatment of rats for 4 weeks with the NO synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME) 50 mg. kg-1. d-1 increased systolic blood pressure to 159+/-12 mm Hg. In animals treated with L-NAME, histological evaluation of renal sections revealed an increased formation of extracellular matrix (Masson's trichrome), and specifically of collagens (Sirius red). A part of this fibrosis was attributed to abnormal collagen I presence, because mRNA expression of the collagen I alpha1 chain (reverse transcription-polymerase chain reaction) and procollagen I formation (radioimmunoassay) were increased 3- and 2.5-fold, respectively, in the renal resistance vessels of hypertensive animals. In subsequent experiments, we examined whether ET-1 was involved in activation of collagen I formation. mRNA expression (RNase protection assay) of preproET-1 and ET-1 content (radioimmunoassay) were 10-fold and 3-fold increased, respectively, in renal microvessels of rats treated with L-NAME. Interestingly, in these vessels, ET-1 (immunostaining) was colocalized with sudanophilic lesions. Bosentan, an ET receptor antagonist (20 mg. kg-1. d-1), coadministered with L-NAME canceled the increased mRNA expression and synthesis of collagen I and attenuated the severity of renal vascular lesions without affecting L-NAME-induced high blood pressure. These data demonstrate that ET-1 synthesis is increased in renal microvessels when NO production is suppressed. In this model of hypertension, ET-1 is a major activator of collagen I formation in renal resistance vessels and participates in the development of renal fibrosis without affecting systolic blood pressure.

Finite element modeling of three-dimensional pulsatile flow in the abdominal aorta: relevance to atherosclerosis.

The infrarenal abdominal aorta is particularly prone to atherosclerotic plaque formation while the thoracic aorta is relatively resistant. Localized differences in hemodynamic conditions, including differences in velocity profiles, wall shear stress, and recirculation zones have been implicated in the differential localization of disease in the infrarenal aorta. A comprehensive computational framework was developed, utilizing a stabilized, time accurate, finite element method, to solve the equations governing blood flow in a model of a normal human abdominal aorta under simulated rest, pulsatile, flow conditions. Flow patterns and wall shear stress were computed. A recirculation zone was observed to form along the posterior wall of the infrarenal aorta. Low time-averaged wall shear stress and high shear stress temporal oscillations, as measured by an oscillatory shear index, were present in this location, along the posterior wall opposite the superior mesenteric artery and along the anterior wall between the superior and inferior mesenteric arteries. These regions were noted to coincide with a high probability-of-occurrence of sudanophilic lesions as reported by Cornhill et al. (Monogr. Atheroscler. 15:13-19, 1990). This numerical investigation provides detailed quantitative data on hemodynamic conditions in the abdominal aorta heretofore lacking in the study of the localization of atherosclerotic disease.

Preglomerular sudanophilia in L-NAME hypertensive rats: involvement of endothelin.

To characterize alterations of renal vessels occurring during systemic hypertension elicited in rats by 5, 10, and 25 days of treatment by the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME)(20 mg/kg daily), preglomerular vasculatures, consisting of arcuate arteries and their branches, interlobular arteries, and afferent arterioles, were isolated by HCl maceration. Blockade of nitric oxide synthase significantly increased tail-cuff systolic blood pressure by 21 +/- 2% and 42 +/- 3% after 5 and 25 days, respectively. Medias of hypertensive arcuate arterial branches and interlobular arteries but not of afferent arterioles had focal deposits of Sudan black-positive lipid droplets. At 25 days, vessel wall thickness increased by 72 +/- 6% along the sudanophilic areas. Immunostaining of sudanophilic lesions with a panel of antibodies unveiled medial cell proliferation, macrophage invasion, immunoreactive vascular cell adhesion molecule-1, and low-density lipoprotein. The frequency of sudanophilic lesions increased with time to affect 26 +/- 2% and 36 +/- 3% of arcuate arterial branches and interlobular arteries, respectively, at 25 days. Hypertensive L-NAME-treated rats developed glomerular injury probed by albuminuria and glomerular immunostaining for alpha-smooth muscle actin. Administration of the nonselective endothelin antagonist bosentan (30 mg/kg daily) blunted the development of sudanophilic lesions during L-NAME treatment without affecting arterial hypertension or degree of glomerular injury. Therefore, L-NAME hypertension leads to rapid development of focal, inflammatory, proliferative, and sudanophilic lesions along preglomerular vessels, suggesting atherosclerosis-like processes. Furthermore, endothelin is a likely mediator in the development of these lesions.

Quantitative analysis of inflammatory cells in aortic atherosclerosis of young adults

Cellular analysis of aortic atherosclerotic lesions has been pursued extensively in recent years, although most of these investigations have involved the detection of inflammatory cells in chronically diseased tissue or artificially induced atherosclerosis in an animal model. Few studies have attempted to quantify accurately, using computer analysis systems, the degree of cellular infiltration in a statistically significant number of samples, in tissue from young adults. In this study, segments of human aortae were collected at autopsy from 29 individuals ranging in age from 15 to 35 years. The tissue was embedded in paraffin and stained using routine histological and automated immunohistochemical staining techniques. The sections were evaluated using advanced image analysis techniques to investigate the differences in cellular composition and cell activation between the dorsal and ventral aspects of the human aorta and to correlate these findings to the age of the subjects. These regions have been previously shown to have a high (dorsal) and low (ventral) probability of developing sudanophilic lesions. Our data demonstrated that statistically different cell populations exist in the dorsal and ventral regions of each vessel. The dorsal aspect (i.e., high-probability region) had a greater number of HAM56 + (36.9% increase, p = 0.0002) and HLA-DRα + cells (44.2% increase, p = 0.0035) than did the ventral surface (i.e., low-probability region), although there were no significant differences in the number of CD43 + lymphocytes. When grouped according to age, results showed significant increases in the dorsal region when considering HAM56 + and HLA-DRα + cells ( p = 0033 and 0.046, respectively). Morphologically, a greater number of foam cell aggregates were found to occur in the dorsal region of the vessel than in the ventral portion. Our results indicate that the microarchitecture and cellular composition of the dorsal and ventral aorta are significantly different, with these variations becoming more marked with age.

Low Atherosclerotic Response of a Strain of Rabbits to Diet-Induced Hypercholesterolemia

In this report we describe the development of two rabbit strains, HAR (high atherosclerotic response) and LAR (low atherosclerotic response), and their propensities to develop atherosclerosis in the aorta despite similar levels of diet-induced hypercholesterolemia. Sixty-two randomly selected male New Zealand White rabbits were fed a cholesterol-enriched diet (0.5%) for 84 days and developed 57 +/- 25% sudanophilic lesions of the aortic surface; 12 rabbits showed a low atherosclerotic response (0% to 30% surface involvement), and 22 rabbits showed a high atherosclerotic response (70% to 100% surface involvement). The offspring of rabbits with low atherosclerotic response were used for breeding the strain of rabbits resistant to atherosclerosis (LAR strain), while the offspring of rabbits with high atherosclerotic response were used for breeding the HAR strain. Controlled breeding was started after the 4th generation and performed for the subsequent 6 generations. Thus, in the LAR rabbits the lipid-stainable surface area of aorta amounted to only 27 +/- 17% after 112 days of cholesterol feeding. On the other hand, in HAR rabbits, aortic surface involvement reached 85 +/- 25% after 112 days on the cholesterol-enriched diet. The measurements of surface area involvement were corroborated also by a significantly lower, chemically determined cholesterol content of the aorta in LAR rabbits. Plasma lipids and lipoproteins were determined at baseline, after 21 and 42 days of cholesterol feeding, and at the time the animals were killed. The plasma cholesterol concentrations of cholesterol-fed HAR and LAR rabbits showed a 13-fold increase after 21 days and a 21-fold increase after 84 days on the cholesterol diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Prophylactic and corrective action of the polyethylene oxide polyox WSR-301 in rats with experimental lipoidosis

Two once-weekly intravenous injections of the polyethylene oxide Polyox WSR-301 (yielding a blood concentration of the order of 5×10−6 g/ml) led to a 38% decrease in the area occupied by sudanophilic lesions in the aortic arch of rats fed an atherogenic diet for two weeks. Perfusion under constant pressure of the formalin-fixed vascular system in the posterior part of the body with physiological saline and then with polyethylene oxide (10−5 g/ml) was without effect in normal rats and in those with mild lipoidosis, but reduced hydrodynamic vascular resistance by 9–14.5% in rats with pronounced lipoidosis. Intravenous injection of polyethylene oxide into anesthetized rats with pronounced lipoidosis in doses that were subthreshold for normal rats (blood concentrations of the polymer were of the order of 10−7 g/ml) caused a 20% decrease in the total peripheral resistance to blood flow, with a 17–20% rise of the blood flow rate in the carotid artery.

6 Development of sudanophilic lesions along the renal preglomerular vasculature during prolonged NG-nitro-L-arginine methyl ester-induced hypertension in rats

6 Development of sudanophilic lesions along the renal preglomerular vasculature during prolonged NG-nitro-L-arginine methyl ester-induced hypertension in rats

Protection from atherosclerosis in vein grafts by a rigid external support.

Atherosclerosis is a common feature of autogenous vein bypass grafts resulting in their long-term failure. Arterial pressure-induced distension is thought to play a major role in the wall thickening of vein grafts, which may in turn favor atherosclerotic complications. In this study, we evaluated the influence of vein distension on the development of atherosclerotic lesions in jugular vein grafts interposed into the common carotid arteries of rabbits. The proximal half of each vein graft was wrapped with a 4-mm-diameter polytetrafluoroethylene graft that reduced the vein graft diameter by 46 +/- 5%. Fourteen animals were fed a 1% cholesterol-rich diet for 8 weeks, and five animals were fed a normal diet. In normocholesterolemic and hypercholesterolemic animals, the wall thickness and the total cross-sectional area were significantly reduced in wrapped compared with unwrapped segments. Foam cells were never observed in normocholesterolemic animals. In hypercholesterolemic rabbits, the sudanophilic lesions covered 62 +/- 4% of the luminal surface in unwrapped segments and 31 +/- 7% in wrapped segments (p < 0.0001). In transverse sections, the surface areas of foam cells were also markedly reduced in wrapped compared with unwrapped segments. Reduction of the wall distension using a rigid external support protected the vein grafts from atherosclerosis, possibly as a result of the decrease in wall thickening that occurred in response to arterialization.

Relation between coronary artery geometry and the distribution of early sudanophilic lesions.

The relationship between the angle formed by the left circumflex (LCX) and left anterior descending (LAD) coronary arteries at the bifurcation of the left main coronary artery (LM) and the location of sudanophilia in the proximal portions of the LCX and LAD, was investigated, using a normalized index of disease severity (relative proximal involvement, RPI) to isolate the local effect of geometry on the predisposition to disease from that of other risk factors. Multiplane angiograms of the left coronary artery system of 15 hearts were digitized and processed to form a three-dimensional representation of the centerline of the lumen (termed the 'axis') of each coronary segment; the LM branch angle was objectively computed from the reconstruction. The coronary vessels were fixed in situ, removed from the hearts, opened longitudinally and stained with Sudan IV. The RPIs of the LAD and LCX were obtained by dividing the percentage sudanophilia seen en face in the first 1 cm of each vessel by the percentage sudanophilia in the first 5 cm. RPI was correlated negatively with LM branch angle, suggesting that a small LM branch angle may be a 'geometric risk factor' for proximal atherosclerotic disease in the daughter vessels. The correlation was stronger for the LCX than the LAD. These results would appear to be consistent with the notion that atherosclerosis is favored where a larger extent of the vessel experiences fluid dynamic wall shears near zero for an appreciable part of the pulsatile cycle.

Cocaine: an independent risk factor for aortic sudanophilia. A preliminary report

Several recent autopsy reports indicate an increased prevalence of coronary atherosclerosis in ischemic heart disease temporally associated with cocaine abuse. The objective of this study was to conduct a retrospective analysis of sudanophilic lesions in young asymptomatic individuals who abused cocaine. Twenty-six cases (15–34-year-old black males) were examined from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. Sixteen subjects (mean age 25 ± 1 years) had a positive toxicologic screen for cocaine and/or its major metabolites at autopsy and were confirmed habitual cocaine abusers. The remaining 10 cases (mean age 24 ± 2 years) were subjects with a negative toxicologic screen at autopsy and no history of illicit drug abuse. Post-mortem blood was collected for lipoprotein analysis and determination of smoking status. The aorta and right coronary arteries were stained with Sudan IV and the degree and extent of sudanophilia was quantitated by image analysis. Multiple linear regression analysis of cocaine, age, smoking status, VLDL + LDL-C/HDL-C ratio and HDL-C as predictor variables of percentage intimal surface involvement, revealed an association between cocaine abuse and the extent of sudanophilia in both the thoracic and abdominal aorta ( P = 0.002 and 0.049, respectively). Analysis of risk factors or of cocaine abuse as predictors of sudanophilia did not achieve statistical significance in the right coronary artery. These preliminary results suggest that habitual use of cocaine, through unknown mechanism(s), increases aortic sudanophilia independent of traditional risk factors.

Accumulation of indium-111-labeled human low density lipoprotein in the rabbit aorta: Implications for nuclear imaging of vascular lesions

Nuclear imaging of atheromata must distinguish lesions from both blood pool and normal arterial tissue. We have examined spatial and temporal variations of indium-111-labeled human low density lipoprotein (LDL) accumulation in rabbit aortas. LDL-derived In-111 activity was time-independent in lesion-resistant regions of aortas from normal and hypercholesterolemic animals (mean 2.9 × 10 −6 percent injected activity per milligram tissue [%IA/mg]) and in lesion-prone regions of normal aortas (mean 7.1 × 10 −6 %IA/mg). In contrast, activity in sudanophilic lesions of hypercholesterolemic rabbit aortas reached a peak of 31 × 10 −6 %IA/mg at 92 hours postinjection. The mean ratio between activity in lesions versus lesion-resistant regions described a broad convex curve with minima of 4:1 at 14 hours and 136 hours and a peak of 14:1 measured at 72 hours postinjection. The mean ratio between In-111 in lesions and blood followed a sigmoid curve, rising exponentially from 1:25 at 14 hours to 1:3 by 72 hours postinjection. We conclude that optimal signal-to-noise ratios for monitoring atheroma-associated LDL-derived radioactivity occur late, not before about 3 days postinjection. Therefore, LDL labeled with In-111 or even longer-lived radionuclides holds the greatest promise for effective clinical nuclear imaging of atherosclerosis.

Attenuation of atherosclerosis in a modified strain of hypercholesterolemic Watanabe rabbits with use of a probucol analogue (MDL 29,311) that does not lower serum cholesterol.

Probucol is a drug that lowers plasma cholesterol in both humans and animals. In low density lipoprotein (LDL) receptor-deficient Watanabe rabbits, probucol reduces the progression of atherosclerosis. This effect may be attributed to the antioxidant and/or the cholesterol-lowering properties of the drug. In the present report we studied the antiatherogenic effect of a probucol analogue (MDL 29,311) that possesses antioxidant activity but that does not lower cholesterol. Modified Watanabe rabbits (11-12 weeks of age) produced by crossing British Brown and Japanese Watanabe rabbits were fed normal chow (n = 8), chow containing 1% probucol (n = 9), or chow containing 0.1% (n = 9), 0.5% (n = 8), or 1% (n = 6) probucol analogue. After 70 days serum cholesterol levels and the percent area of sudanophilic lesions in the thoracic region of aortas were determined. Total serum cholesterol was significantly lowered (p less than 0.05) in the probucol group (560 +/- 54 mg/dl) compared with that of controls receiving no drug (731 +/- 67 mg/dl) but was not lowered in the analogue groups (722-802 mg/dl). The lesioned area (mean% +/- SEM) in the probucol group (16 +/- 3) was significantly lower (p less than 0.01) than in the controls (52 +/- 8). There were 43 +/- 7%, 33 +/- 8%, and 35 +/- 5% of lesions for the 0.1%, 0.5%, and 1% analogue groups, respectively. After combining the data for the 0.5% and 1% analogue groups, the value (34%) was lower than that of the controls and almost reached significance (p = 0.066). The mean serum drug concentration in the 1% probucol group was 58 +/- 4 micrograms/ml compared with 13 +/- 2, 44 +/- 8, and 74 +/- 8 micrograms/ml for the 0.1%, 0.5%, and 1% analogue groups, respectively. Thus, the decreased effectiveness of the probucol analogue in preventing atherosclerosis could not be explained by a lack of bioavailability. LDLs isolated from rabbits treated with the drug were resistant to Cu(2+)-induced lipid peroxidation, as determined by thiobarbituric acid-reactive substances. The resistance within the analogue groups was dependent on the number of antioxidant molecules per LDL particle. However, there was no significant difference in atherosclerotic lesions between these two groups, suggesting, although not definitively, that the maximal antiatherogenic effect had been reached. Our data suggest that the antioxidant activity of this class of compounds may play an important role in reducing atherosclerosis, but not in reducing cholesterol levels, and that hypocholesterolemic and possibly other activities of probucol might further enhance its antiatherogenic activity.

高脂血症ウサギの大動脈弓分岐分流部の内皮細胞の形態学的研究

Morphometric studies of endothelial cells on the aortic surface of flow dividers of aortic branchings to brachiocephalic (BC) and subclavian (SA) arteries were performed in either normo- or cholesterol-fed rabbits using scanning electron microscopy.The cells of BC in the sudanophilic region were variously ellipsoidal, and somewhat round. All of the ellipsoidal cells were arranged multidirectionally, presumably caused by separation of the blood flow. The region was located just downstream from the leading edge covered by elongated fusiform endothelial cells arranged in alignment and parallel to blood flow. The apex of the flow divider, or stagnation point was covered by round cells. SA had also the sudanophilic region covered by ellipsoidal endothelial cells, which was downstream from the stagnation point which was not coincidental with the apex of the flow divider of SA. The areas covered by either round or elongated fusiform cells were free from lipid deposition.It can be concluded that the sudanophilic lesions in hyperlipidemic rabbits would evolve where endothelial cells might be exposed to moderately mean low shear stress, either laminar (SA) or turbulent (BC). Hence the high shear theory of atherogenesis of animals should be reexamined.