Lesion Cross-sectional Area Research Articles

Deficiency of PXR decreases atherosclerosis in apoE-deficient mice

The pregnane X receptor (PXR, also known as SXR) is a nuclear hormone receptor activated by xenobiotics as well as diverse sterols and their metabolites. PXR functions as a xenobiotic sensor to coordinately regulate xenobiotic metabolism via transcriptional regulation of xenobiotic-detoxifying enzymes and transporters. Recent evidence indicates that PXR may also play an important role in lipid homeostasis and atherosclerosis. To define the role of PXR in atherosclerosis, we generated PXR and apoE double knockout (PXR(-/-)apoE(-/-)) mice. Here we show that deficiency of PXR did not alter plasma triglyceride and cholesterol levels in apoE(-/-) mice. However, PXR(-/-)apoE(-/-) mice had significantly decreased atherosclerotic cross-sectional lesion area in both the aortic root and brachiocephalic artery by 40% (P < 0.01) and 60% (P < 0.001), respectively. Interestingly, deficiency of PXR reduced the expression levels of CD36, lipid accumulation, and CD36-mediated oxidized LDL uptake in peritoneal macrophages of PXR(-/-)apoE(-/-) mice. Furthermore, immunofluorescence staining showed that PXR and CD36 were expressed in the atherosclerotic lesions of apoE(-/-) mice, and the expression levels of PXR and CD36 were diminished in the lesions of PXR(-/-)apoE(-/-) mice. Our findings indicate that deficiency of PXR attenuates atherosclerosis development, which may result from decreased CD36 expression and reduced lipid uptake in macrophages.

Antiatherogenic effect of pioglitazone on uremic apolipoprotein E knockout mice by modulation of the balance of regulatory and effector T cells

ObjectiveUremia markedly accelerates atherogenesis, but the pathogenesis remains to be elucidated and effective anti-atherogenic treatments are needed. The aim of this study was to investigate the relationship between accelerated atherosclerosis (AS) and the balance of regulatory/effector T cells (Treg/Teff) in uremic apolipoprotein E knockout (apoE−/−) mice, and the effect of pioglitazone on uremic AS and possible mechanisms. Methods and resultsUremia was induced surgically in 8-week-old male apoE−/− mice. Two weeks after induction of uremia, the mice were randomized to receive pioglitazone (daily oral gavage with 20mg/kg) or vehicle. Control apoE−/− mice were sham-operated and received vehicle. After 8 weeks’ treatment, all mice were sacrificed. The cross-sectional area of atherosclerotic lesions at the aortic root was significantly larger and plaques were unstable in uremic mice, which was associated with a Treg/Teff imbalance (Treg down-regulated/Teff up-regulated) compared with controls. Renal function and the percentage of Treg cells in splenocytes were negatively correlated in control and uremic mice that received vehicle. Treatment with pioglitazone dramatically inhibited AS progression, stabilized plaque and modulated the Treg/Teff imbalance (up-regulated Treg/down-regulated Teff) in uremic mice, without influencing serum lipid profiles and blood glucose. In vitro, oxidized low density lipoprotein induced a Treg/Teff imbalance in splenocytes from uremic mice. Pioglitazone modulated the imbalance by upregulating Treg cells and downregulating Teff cells. The former was not abolished by the peroxisome proliferator-activated receptor (PPAR)γ antagonist GW9662, whereas the latter was completely abolished by GW9662. ConclusionPioglitazone ameliorates accelerated AS in uremic apoE−/− mice, probably through PPARγ-independent and -dependent mechanisms to modulate the Treg/Teff imbalance.

Left ventricular dysfunction with reduced functional cardiac reserve in diabetic and non-diabetic LDL-receptor deficient apolipoprotein B100-only mice

BackgroundLack of suitable mouse models has hindered the studying of diabetic macrovascular complications. We examined the effects of type 2 diabetes on coronary artery disease and cardiac function in hypercholesterolemic low-density lipoprotein receptor-deficient apolipoprotein B100-only mice (LDLR-/-ApoB100/100).Methods and results18-month-old LDLR-/-ApoB100/100 (n = 12), diabetic LDLR-/-ApoB100/100 mice overexpressing insulin-like growth factor-II (IGF-II) in pancreatic beta cells (IGF-II/LDLR-/-ApoB100/100, n = 14) and age-matched C57Bl/6 mice (n = 15) were studied after three months of high-fat Western diet. Compared to LDLR-/-ApoB100/100 mice, diabetic IGF-II/LDLR-/-ApoB100/100 mice demonstrated more calcified atherosclerotic lesions in aorta. However, compensatory vascular enlargement was similar in both diabetic and non-diabetic mice with equal atherosclerosis (cross-sectional lesion area ~60%) and consequently the lumen area was preserved. In coronary arteries, both hypercholesterolemic models showed significant stenosis (~80%) despite positive remodeling. Echocardiography revealed severe left ventricular systolic dysfunction and anteroapical akinesia in both LDLR-/-ApoB100/100 and IGF-II/LDLR-/-ApoB100/100 mice. Myocardial scarring was not detected, cardiac reserve after dobutamine challenge was preserved and ultrasructural changes revealed ischemic yet viable myocardium, which together with coronary artery stenosis and slightly impaired myocardial perfusion suggest myocardial hibernation resulting from chronic hypoperfusion.ConclusionsLDLR-/-ApoB100/100 mice develop significant coronary atherosclerosis, severe left ventricular dysfunction with preserved but diminished cardiac reserve and signs of chronic myocardial hibernation. However, the cardiac outcome is not worsened by type 2 diabetes, despite more advanced aortic atherosclerosis in diabetic animals.

Role of Heparanase on Hepatic Uptake of Intestinal Derived Lipoprotein and Fatty Streak Formation in Mice

BackgroundHeparanase modulates the level of heparan sulfate proteoglycans (HSPGs) which have an important role in multiple cellular processes. Recent studies indicate that HSPGs have an important function in hepatic lipoprotein handling and processes involving removal of lipoprotein particles.Principal FindingsTo determine the effects of decreased HSPGs chain length on lipoprotein metabolism and atherosclerosis, transgenic mice over-expressing the human heparanase gene were studied.Hepatic lipid uptake in hpa-Tg mice were evaluated by giving transgenic mice oral fat loads and labeled retinol. Sections of aorta from mice over-expressing heparanase (hpa-Tg) and controls (C57/BL6) fed an atherogenic diet were examined for evidence of atherosclerosis. Heparanase over-expression results in reduced hepatic clearance of postprandial lipoproteins and higher levels of fasting and postprandial serum triglycerides. Heparanase over-expression also induces formation of fatty streaks in the aorta. The mean lesion cross-sectional area in heparanase over-expressing mice was almost 6 times higher when compared to control mice (23,984 µm2±5,922 vs. 4,189 µm2±1,130, p<0.001).ConclusionsOver-expression of heparanase demonstrates the importance of HSPGs for the uptake of intestinal derived lipoproteins and its role in the formation of fatty streaks.

Feeding a thermally oxidised fat inhibits atherosclerotic plaque formation in the aortic root of LDL receptor-deficient mice

Activators of PPARα have been demonstrated to inhibit atherosclerosis development due to lipid lowering in plasma and direct protective effects on the vasculature. Because dietary oxidised fats (OF) have strong PPARα-activating and lipid-lowering properties, we hypothesised that dietary OF has also an inhibitory influence on atherosclerosis development. To verify our hypothesis, we investigated the effect of feeding diets containing an OF (a 92 : 8 mixture of heated (170°C, 48 h) hydrogenated palm fat and fresh sunflower oil) compared with a fresh fat (fresh hydrogenated palm fat) on the development of atherosclerotic lesions in LDL receptor-deficient (LDLR- / - ) mice. We observed that a dietary OF caused a strong up-regulation of PPARα-regulated genes in the liver and a marked reduction in plasma concentrations of cholesterol and TAG (P < 0·05). Cross-sectional lesion area and the lipids and collagen levels in the aortic root were approximately 40-50 % lower in mice fed diets containing OF than in those fed diets containing fresh fat (P < 0·05). Immunohistochemical analysis of aortic root sections revealed an about 8-fold increased expression of PPARα and a markedly reduced expression of the proinflammatory vascular cell adhesion molecule-1 and smooth muscle cell (SMC)-specific marker α-actin in LDLR- / - mice fed OF (P < 0·05). We postulate that OF exert anti-atherogenic effects by activation of PPARα both in the liver, which contributes to lipid lowering in plasma, and in the vasculature, which inhibits pro-atherogenic events such as monocyte recruitment and SMC proliferation and migration.

Silencing of either SR-A or CD36 reduces atherosclerosis in hyperlipidaemic mice and reveals reciprocal upregulation of these receptors

Macrophage scavenger receptor A (SR-A) and class B scavenger receptor CD36 (CD36) contribute to foam cell formation and atherogenesis via uptake of modified lipoproteins. So far, the role of these scavenger receptors has been studied mainly using knockout models totally lacking these receptors. We studied the role of SR-A and CD36 in foam cell formation and atherogenesis by RNA interference (RNAi)-mediated silencing, which is a clinically feasible method to down-regulate the expression of these receptors. We constructed lentivirus vectors encoding short hairpin RNAs (shRNAs) against mouse SR-A and CD36. Decreased SR-A but not CD36 expression led to reduced foam cell formation caused by acetylated low-density lipoprotein (LDL) in mouse macrophages, whereas the uptake of oxidized LDL was not altered. More importantly, silencing of SR-A upregulates CD36 and vice versa. In LDL receptor-deficient apolipoprotein B100 (LDLR(-/-)ApoB(100/100)) mice kept on a western diet, silencing of either SR-A or CD36 in bone marrow cells led to a marked decrease (37.4 and 34.2%, respectively) in cross-sectional lesion area, whereas simultaneous silencing of both receptors was not effective. Our results suggest that silencing of either SR-A or CD36 alone reduces atherogenesis in mice. However, due to reciprocal upregulation, silencing of both SR-A and CD36 is not effective.

MR IMAGING FEATURES OF SURGICALLY INDUCED CORE LESIONS IN THE EQUINE SUPERFICIAL DIGITAL FLEXOR TENDON

Tendon injuries are common in athletic humans and horses. Ultrasonography is the diagnostic method of choice in horses with tendon injuries but there is increasing application of magnetic resonance (MR) imaging to monitor and follow-up tendon healing. A core lesion was created in the superficial digital flexor tendon (SDFT) of each forelimb of four horses. One of the four horses was euthanized at 2, 4, 8, and 12 weeks after creation of the lesion. MR examinations of the SDFT were performed immediately post mortem in a 1.5 T Siemens Symphony magnet and compared with histologic findings. Measurements from the MR images were also compared to ultrasonographic measurements available from the same lesions. Tendon lesions appeared as well-circumscribed hyperintensities in the core of the SDFT on all pulse sequences. Lesions were most conspicuous on fat-suppressed fast low angle shot (FLASH) sequences and least conspicuous on T2 transverse dual turbo spin echo (T2 TSE) sequences. The signal-difference-to-noise ratio decreased with the age of the lesion in all sequences in this study. Twelve-week-old lesions were not visible on T2 TSE images but in all other sequences the lesion remained hyperintense. The lesion volume and maximum cross-sectional area of core lesions were significantly smaller in T2 TSE images than in other MR sequences. The lesion volume and maximum cross-sectional area of core lesions were significantly larger in proton density, T1, and FLASH sequences and significantly smaller in T2 sequences than when measured from ultrasonographic images. Through comparison between sequences, MR imaging may be able to provide information on various stages of tendon healing.

Activation of PXR induces hypercholesterolemia in wild-type and accelerates atherosclerosis in apoE deficient mice

The nuclear hormone receptor pregnane X receptor (PXR; also called SXR) functions as a xenobiotic sensor to coordinately regulate xenobiotic metabolism via transcriptional regulation of xenobiotic-detoxifying enzymes and transporters. Although many clinically relevant PXR ligands have been shown to affect cholesterol levels, the role of PXR in cholesterol homeostasis and atherosclerosis has not been thoroughly investigated. Here, we report that activation of PXR by feeding the PXR agonist pregnenolone 16alpha-carbonitrile (0.02%) for 2 weeks to wild-type (WT) mice significantly increased total cholesterol levels and atherogenic lipoproteins VLDL and LDL levels, but had no effect in PXR knockout (PXR(-/-)) mice. Chronic PXR activation in atherosclerosis prone apolipoprotein E deficient (ApoE(-/-)) mice was found to decrease HDL levels and increase atherosclerotic cross-sectional lesion area at both the aortic root and in the brachiocephalic artery by 54% (P < 0.001) and 116% (P < 0.01), respectively. PXR activation significantly regulated genes in the liver involved in lipoprotein transportation and cholesterol metabolism, including CD36, ApoA-IV, and CYP39A1, in both WT and ApoE(-/-) mice. Furthermore, PXR activation can increase CD36 expression and lipid accumulation in peritoneal macrophages of ApoE(-/-) mice. In summary, PXR activation in WT mice increases levels of the atherogenic lipoproteins VLDL and LDL, whereas in ApoE(-/-) mice, PXR increases atherosclerosis, perhaps by diminishing levels of the antiatherogenic ApoA-IV and increasing lipid accumulation in macrophages.

Plasma rico em plaquetas no tratamento de tendinite induzida em eqüinos: avaliação ultra-sonográfica

O objetivo deste trabalho foi estudar o efeito do plasma rico em plaquetas (PRP) no tratamento da tendinite induzida no tendão do músculo flexor digital superficial (TFDS) de eqüinos mediante avaliação ultra-sonográfica. Para isso foram utilizados seis eqüinos hígidos machos castrados, com idade de 8-15 anos (x=12 anos). A tendinite do TFDS foi provocada em ambos os membros torácicos, mediante a administração intratendínea de 2,5mg de colagenase (2,5mg.µL-1), sendo esse procedimento considerado o início da fase experimental. Doze dias após a indução da tendinite, os animais foram submetidos a dois tratamentos: sendo que na lesão efetuada no TFDS direito (grupo tratado, GT), foram administrados 2,5mL de PRP ativado com cloreto de cálcio a 0,0125mol.L-1, contendo concentrações variando de 320.000 a 500.000 plaquetas.µL-1; na tendinite do TFDS esquerdo (grupo controle, GC), foram injetados 2,5mL de solução salina a 0,9%. Após cinco dias, os animais foram submetidos à atividade física controlada e progressiva durante 30 dias. Os exames ultra-sonográficos foram realizados antes e após indução da tendinite (48 horas após e no 7º, 12º, 14º, 21º, 28º, 35º, 42º dias do experimento), sendo avaliado a área transversal do tendão (ATT), área transversal da lesão (ATL), o percentual da ATL, a intensidade e ecogenicidade da lesão, assim como o paralelismo das fibras colágenas. Os resultados revelaram redução (P&lt;0,05) da ATL e do grau de ecogenicidade da lesão em função do tempo, mas com diferença (P&lt;0,05) entre grupos apenas para ATL, com valores menores no GT. O tratamento com PRP proporciona maior redução da área da lesão, mensurada por ultra-sonografia.

Antibodies against electronegative LDL inhibit atherosclerosis in LDLr-/- mice

In order to determine the effect of antibodies against electronegative low-density lipoprotein LDL(-) on atherogenesis, five groups of LDL low receptor-deficient (LDLr-/-) mice (6 per group) were immunized with the following antibodies (100 microg each): mouse anti-LDL(-) monoclonal IgG2b, rabbit anti-LDL(-) polyclonal IgG or its Fab fragments and mouse irrelevant monoclonal IgG and non-immunized controls. Antibodies were administered intravenously one week before starting the hypercholesterolemic diet (1.25% cholesterol) and then every week for 21 days. The passive immunization with anti-LDL(-) monoclonal IgG2b, polyclonal antibody and its derived Fab significantly reduced the cross-sectional area of atherosclerotic lesions at the aortic root of LDLr-/- mice (28.8 +/- 9.7, 67.3 +/- 17.02, 56.9 +/- 8.02 microm(2) (mean +/- SD), respectively) compared to control (124.9 +/- 13.2 microm(2)). Vascular cell adhesion molecule-1 protein expression, quantified by the KS300 image-analyzing software, on endothelium and the number of macrophages in the intima was also decreased in aortas of mice treated with anti-LDL(-) monoclonal antibody (3.5 +/- 0.70 per field x 10) compared to controls (21.5 +/- 3.5 per field x 10). Furthermore, immunization with the monoclonal antibody decreased the concentration of LDL(-) in blood plasma (immunized: 1.0 +/- 1.4; control: 20.5 +/- 3.5 RLU), the amount of cholesterol oxides in plasma (immunized: 4.7 +/- 2.7; control: 15.0 +/- 2.0 pg COx/mg cholesterol) and liver (immunized: 2.3 +/- 1.5; control: 30.0 +/- 26.0 pg COx/mg cholesterol), and the hepatic content of lipid hydroperoxides (immunized: 0.30 +/- 0.020; control: 0.38 +/- 0.15 ng/mg protein). In conclusion, antibodies against electronegative LDL administered intravenously may play a protective role in atherosclerosis.

Abstract 1948: Over-expression of HSP27 Provides Chronic Atheroprotection: Reductions in Foam Cell Content and Inflammatory Responses

Introduction: Heat Shock Protein 27 (HSP27) was recently shown by our laboratory to be a biomarker of atherosclerosis and after 4 weeks of a high fat diet (HFD) apoE −/− mice that over-express HSP27 (or apoE −/− HSP27 o/e mice) show a marked attenuation of aortic lesion size compared to apoE −/− mice - but only in females (ATVB 20005; Circ Res in press). Moreover, we demonstrated that serum HSP27 levels were inversely related to atherosclerotic burden, estrogens mediated the release of HSP27 from cells and extracellular HSP27 bound to Scavenger Receptor-A where it could competitively inhibit acLDL uptake. Purpose/Methods: The goal of this study was to determine if and how HSP27 over-expression persistently attenuates atherogenesis in apoE −/− mice fed a HFD for 12 weeks. Results: Compared to female apoE −/− mice, female apoE −/− HSP27 o/e mice showed persistent reductions in aortic (en face) lesion area and aortic sinus cross-sectional lesion area at 12 weeks (e.g., 38% and 39% respectively vs. 35% and 40% after 4 weeks of HFD). Although our original studies revealed that male apoE −/− HSP27 o/e mice had no protection from atherogenesis after 4 weeks of a HFD, in the current study we noted that 12 weeks of a HFD resulted in a 17% reduction in aortic (en face) lesion area and a 24% attenuation in aortic sinus cross-sectional lesion area with HSP27 over-expression. While lesions observed after 4 weeks of HFD consisted mainly of lipid-laden foam macrophages, after 12 weeks of HFD the histopathology was different and included a distinct foam cell layer (or FCL) luminal to a deeper necrotic layer (e.g., with cholesterol crystals). The FCL area was reduced in size in apoE −/− HSP27 o/e vs. apoE −/− mice (e.g., −63% in females, p=0.03; and −48% in males, p=0.02). In vitro, macrophages from apoE −/− HSP27 o/e mice showed a reduction in TNF-α expression compared to apoE −/− mice (e.g., 40% at baseline, and 55% after LPS provocation). Conclusions: Over-expression of HSP27 provides a persistent atheroprotective effect that benefits both sexes. Chronic lesions are not only smaller in size with HSP27 over-expression but show fewer foam cells and macrophages are less pro-inflammatory. These results highlight a potential clinical role for chronic HSP27 modulation for atheroprotection.

The development of endometriosis is dependent on the presence of dendritic cells in mice

OBJECTIVE: Endometriosis affects 10-15% of women of reproductive age and is associated with pelvic pain and infertility. Recently, we have shown that dendritic cells (DC) supplementation led to the enhancement of endometriosis lesion growth and of intra-lesion angiogenesis. In this study, we investigated whether the development of endometriosis is dependent on the presence of endogenous DC.DESIGN: Prospective study using a surgical model of endometriosis in mice.MATERIALS AND METHODS: Surgical induction of endometriosis was performed in 8-10 week old female mice. Briefly, under anesthesia, a midline laparotomy was performed, uterine horns were removed, and 2-mm biopsy punch samples were sutured to the peritoneal wall. After 8 days, mice were killed, their abdomens were opened through the same incision and lesions were measured in two perpendicular diameters (D1 and D2) and the cross-sectional lesion area calculated using the formula D1xD2xπ/4. Single cell suspensions were analyzed by flow cytometry. In order to ablate DC, we utilized CD11c-DTR/GFP transgenic mice (C57Bl/6 background), in which DC can be ablated in vivo. Administration of diphtheria toxin (DT) into the transgenic mice that express the primate DT receptor (DTR), resulted in depletion of CD11c+DC. Endometriosis was induced in 10 CD11c-DTR/GFP transgenic mice and in 10 C57Bl/6 control mice. The mice were allocated to 4 groups (n=5 mice per group): I: C57Bl/6 treated with vehicle; II: C57Bl/6 treated with DT; III: CD11c-DTR/GFP transgenic mice treated with DT; IV: CD11c-DTR/GFP transgenic mice treated with vehicle. On day 0, endometriosis was induced. On days 2, 5, and 9, DT or vehicle was administered. All mice were sacrificed on day 10, the lesions were measured, and surgically removed from the abdominal cavity.RESULTS: In CD11c-DTR/GFP transgenic mice that were treated with DT (Group III) the endometriotic lesions were significantly smaller than that of all the other groups (ANOVA) (i.e. Group I: 5.25±1.18 mm2; Group II: 4.73±1.11 mm2; Group III: 1.09 ± 0.38 mm2; Group IV: 5.12±1.09 mm2, p<0.001). Single cell suspensions of endometriosis lesions were analyzed by flow cytometry, showing a near complete ablation of DC in Group III while no ablation was observed in the other 3 groups of mice.CONCLUSIONS: Our results indicate that endometriosis is dependent on the infiltrating DC population. Therapies designed to inhibit DC infiltration could target endometriosis in the future. This possibility warrants further studies. OBJECTIVE: Endometriosis affects 10-15% of women of reproductive age and is associated with pelvic pain and infertility. Recently, we have shown that dendritic cells (DC) supplementation led to the enhancement of endometriosis lesion growth and of intra-lesion angiogenesis. In this study, we investigated whether the development of endometriosis is dependent on the presence of endogenous DC. DESIGN: Prospective study using a surgical model of endometriosis in mice. MATERIALS AND METHODS: Surgical induction of endometriosis was performed in 8-10 week old female mice. Briefly, under anesthesia, a midline laparotomy was performed, uterine horns were removed, and 2-mm biopsy punch samples were sutured to the peritoneal wall. After 8 days, mice were killed, their abdomens were opened through the same incision and lesions were measured in two perpendicular diameters (D1 and D2) and the cross-sectional lesion area calculated using the formula D1xD2xπ/4. Single cell suspensions were analyzed by flow cytometry. In order to ablate DC, we utilized CD11c-DTR/GFP transgenic mice (C57Bl/6 background), in which DC can be ablated in vivo. Administration of diphtheria toxin (DT) into the transgenic mice that express the primate DT receptor (DTR), resulted in depletion of CD11c+DC. Endometriosis was induced in 10 CD11c-DTR/GFP transgenic mice and in 10 C57Bl/6 control mice. The mice were allocated to 4 groups (n=5 mice per group): I: C57Bl/6 treated with vehicle; II: C57Bl/6 treated with DT; III: CD11c-DTR/GFP transgenic mice treated with DT; IV: CD11c-DTR/GFP transgenic mice treated with vehicle. On day 0, endometriosis was induced. On days 2, 5, and 9, DT or vehicle was administered. All mice were sacrificed on day 10, the lesions were measured, and surgically removed from the abdominal cavity. RESULTS: In CD11c-DTR/GFP transgenic mice that were treated with DT (Group III) the endometriotic lesions were significantly smaller than that of all the other groups (ANOVA) (i.e. Group I: 5.25±1.18 mm2; Group II: 4.73±1.11 mm2; Group III: 1.09 ± 0.38 mm2; Group IV: 5.12±1.09 mm2, p<0.001). Single cell suspensions of endometriosis lesions were analyzed by flow cytometry, showing a near complete ablation of DC in Group III while no ablation was observed in the other 3 groups of mice. CONCLUSIONS: Our results indicate that endometriosis is dependent on the infiltrating DC population. Therapies designed to inhibit DC infiltration could target endometriosis in the future. This possibility warrants further studies.

Effect of treatment with human apolipoprotein A-I on atherosclerosis in uremic apolipoprotein-E deficient mice

Objective Uremia markedly increases the risk of atherosclerosis. Thus, effective anti-atherogenic treatments are needed for uremic patients. This study examined effects of non-lipidated recombinant human apoA-I (h-apoA-I) and a recombinant trimeric apoA-I molecule (TripA-I) on lipid metabolism and atherosclerosis in uremic apoE−/− mice. Methods and results Upon intraperitoneal injection, h-apoA-I and TripA-I rapidly associated with plasma HDL and reduced mouse apoA-I plasma levels without affecting total or HDL cholesterol concentrations. The plasma half-life was ∼36 h for TripA-I and ∼16 h for h-apoA-I. Injection of h-apoA-I (100 mg/kg) or TripA-I (100 mg/kg) twice weekly for 7 weeks did not affect the cross-sectional area of atherosclerotic lesions in the aortic root, or the en face lesion area and cholesterol content in the thoracic aorta in uremic apoE−/− mice. Also, the treatments did not affect expression of selected inflammatory genes in the thoracic aorta or plasma concentrations of soluble ICAM-1 and VCAM-1. However, h-apoA-I-treated mice had larger smooth muscle cell-staining areas in aortic root plaques than PBS-treated mice (4.8 ± 0.8% vs. 2.5 ± 0.6%, P < 0.05). Conclusions The data suggest that long-term treatment with non-lipidated h-apoA-I or TripA-I might affect plaque composition but does not reduce atherosclerotic lesion size in uremic apoE−/− mice.

Why are arteries the size they are?

sones and shirey ([12][1]) performed the first coronary artery angiogram by accident in 1958. While injecting contrast material for a left ventricular angiogram, the catheter slipped out of the ventricle and into the right coronary artery. Sones immediately recognized the advantage of visualizing

Clinical features and treatment of retropharyngeal abscess in children

To characterize presentation, treatment, and outcomes of pediatric retropharyngeal abscess (RPA) and determine optimal treatment. Retrospective cohort. Chart review of 162 pediatric patients with RPA. Initial treatment was surgery in 126 and intravenous antibiotics in 36, of which 17 required surgery. Findings were negative in 30, murky fluid in 34, and pus in 79. Factors predicting positive surgical drainage were duration of symptoms for more than 2 days, prior antibiotic treatment, and CT lesion cross-sectional area >2.0 cm(2). A history of rash was a negative predictor. The mean length of stay (LOS) was 4.8 vs 3.6 days (P = 0.14), and duration of fever (DOF) was 2.5 vs 1.4 days (P = 0.01) for patients with no fluid and fluid at surgery, respectively. For antibiotic vs surgery groups, LOS was 4.4 vs 3.6 days (P = 0.14) and DOF was 2.4 versus 1.5 days (P = 0.0061). These predictive factors may be useful in selecting patients with retropharyngeal abscesses who might be treated with intravenous antibiotics alone.

Squalene in a sex-dependent manner modulates atherosclerotic lesion which correlates with hepatic fat content in apoE-knockout male mice

Background Squalene is an intermediate of cholesterol biosynthesis which can be obtained from the diet where it is abundant, for example, in olive oil. The effect of this isoprenoid on the development of atherosclerosis was investigated on apoE-knockout mice. Methods and results Two groups of animals, separated according to sex, were fed on standard chow diet: the control group receiving only vehicle and the second group an aqueous solution of squalene to provide a dose of 1 g/kg/day in male and female mice. This treatment was maintained for 10 weeks. At the end of this period, plasma lipid parameters, oxidative stress markers and hepatic fat were measured as well as cross-sectional lesion area of aortic root in both groups. Data showed that in males squalene feeding reduced atherosclerotic lesion area independently of plasma lipids and activation of circulating monocytes. In contrast, squalene intake did not decrease lesion area in females, despite reducing plasma cholesterol and triglycerides, isoprostane and percentage of Mac-1 expressing white cells. In males, atherosclerotic lesion area was positively and significantly associated with hepatic fat content and the plasma triglycerides were also strongly associated with liver weight. Conclusions These results indicate that administration of squalene modulates lesion development in a gender specific manner, and that accumulation of hepatic fat by liver is highly correlated with lesion progression in males. Hence, squalene administration could be used as a safe alternative to correct hepatic steatosis and atherosclerosis particularly in males.

Hepatic ABCG5/G8 overexpression reduces apoB-lipoproteins and atherosclerosis when cholesterol absorption is inhibited

We previously reported that liver-specific overexpression of ABCG5/G8 in mice is not atheroprotective, suggesting that increased biliary cholesterol secretion must be coupled with decreased intestinal cholesterol absorption to increase net sterol loss from the body and reduce atherosclerosis. To evaluate this hypothesis, we fed low density lipoprotein receptor-knockout (LDLr-KO) control and ABCG5/G8-transgenic (ABCG5/G8-Tg)xLDLr-KO mice, which overexpress ABCG5/G8 only in liver, a Western diet containing ezetimibe to reduce intestinal cholesterol absorption. On this dietary regimen, liver-specific ABCG5/G8 overexpression increased hepatobiliary cholesterol concentration and secretion rates (1.5-fold and 1.9-fold, respectively), resulting in 1.6-fold increased fecal cholesterol excretion, decreased hepatic cholesterol, and increased (4.4-fold) de novo hepatic cholesterol synthesis versus LDLr-KO mice. Plasma lipids decreased (total cholesterol, 32%; cholesteryl ester, 32%; free cholesterol, 30%), mostly as a result of reduced non-high density lipoprotein-cholesterol and apolipoprotein B (apoB; 36% and 25%, respectively). ApoB-containing lipoproteins were smaller and lipid-depleted in ABCG5/G8-TgxLDLr-KO mice. Kinetic studies revealed similar 125I-apoB intermediate density lipoprotein/LDL fractional catabolic rates, but apoB production rates were decreased 37% in ABCG5/G8-TgxLDLr-KO mice. Proximal aortic atherosclerosis decreased by 52% (male) and 59% (female) in ABCG5/G8-TgxLDLr-KO versus LDLr-KO mice fed the Western/ezetimibe diet. Thus, increased biliary secretion, resulting from hepatic ABCG5/G8 overexpression, reduces atherogenic risk in LDLr-KO mice fed a Western diet containing ezetimibe. These findings identify distinct roles for liver and intestinal ABCG5/G8 in modulating sterol metabolism and atherosclerosis.

Addition of dietary fat to cholesterol in the diets of LDL receptor knockout mice: effects on plasma insulin, lipoproteins, and atherosclerosis

The factors underlying cardiovascular risk in patients with diabetes have not been clearly elucidated. Efforts to study this in mice have been hindered because the usual atherogenic diets that contain fat and cholesterol also lead to obesity and insulin resistance. We compared plasma glucose, insulin, and atherosclerotic lesion formation in LDL receptor knockout (Ldlr(-/-)) mice fed diets with varying fat and cholesterol content that induced similar lipoprotein profiles. Ldlr(-/-) mice fed a high-fat diet developed obesity, mild hyperglycemia, hyperinsulinemia, and hypertriglyceridemia. Quantitative and qualitative assessments of atherosclerosis were unchanged in diabetic Ldlr(-/-) mice fed a high-fat diet compared with lean nondiabetic control mice after 20 weeks of diet. Although one group of mice fed diets for 40 weeks had larger lesions at the aortic root, this was associated with a more atherogenic lipoprotein profile. The presence of a human aldose reductase transgene had no effect on atherosclerosis in fat-fed Ldlr(-/-) mice with mild diabetes. Our data suggest that when lipoprotein profiles are similar, addition of fat to a cholesterol-rich diet does not increase atherosclerotic lesion formation in Ldlr(-/-) mice.

Osteoprotegerin Inactivation Accelerates Advanced Atherosclerotic Lesion Progression and Calcification in Older ApoE −/− Mice

Osteoprotegerin (OPG), a member of the tumor necrosis factor (TNF) superfamily of proteins, plays an important role in bone remodeling and is expressed in both mouse and human atherosclerotic lesions. The current study was designed to assess whether OPG plays a role in the progression and calcification of advanced atherosclerotic lesions in apoE(-/-) mice. Atherosclerotic lesion area and composition and aortic calcium content were examined in mice deficient in both OPG and apolipoprotein E (OPG(-/-).apoE(-/-) mice) at 20, 40, and 60 weeks of age. Littermate OPG(+/+).apoE(-/-) mice were used as controls. The average cross-sectional area of lesions in the innominate arteries was increased in OPG(-/-).apoE(-/-) mice at 40 and 60 weeks of age. The increase in lesion area was coupled with a reduced cellularity and an increase in connective tissue including laminated layers of elastin. Sixty-week-old OPG(-/-).apoE(-/-) mice also had an increase in the area of calcification of the lesions. There were no differences in markers of plaque stability. In vitro, OPG induced matrix metalloproteinase-9 (MMP-9) activity in macrophages and smooth muscle cells and acted as a survival factor for serum-deprived smooth muscle cells. OPG inhibits advanced plaque progression by preventing an increase in lesion size and lesion calcification. OPG may act as a survival factor and may modulate MMP9 production in vascular cells.

Aggressive Very Low-Density Lipoprotein (VLDL) and LDL Lowering by Gene Transfer of the VLDL Receptor Combined with a Low-Fat Diet Regimen Induces Regression and Reduces Macrophage Content in Advanced Atherosclerotic Lesions in LDL Receptor-Deficient Mice

Very low-density lipoprotein (VLDL) and LDL plasma levels are associated with cardiovascular mortality. Whereas VLDL/LDL lowering causes regression of early atherosclerotic lesions, less is known about the effects of aggressive lipid lowering on regression of advanced complex lesions. We therefore investigated the effect of VLDL/LDL lowering on pre-existing lesions in LDL receptor-deficient mice. Mice fed a high-fat diet for 16 weeks developed advanced lesions with fibrous caps, necrotic cores, and cholesterol clefts in the brachiocephalic artery. After an additional 14 weeks on a low-fat diet, plasma cholesterol levels decreased from 21.0 +/- 2.6 to 8.4 +/- 0.6 mmol/L, but lesions did not regress. Levels of VLDL/LDL were further lowered by using a helper-dependent adenovirus encoding the VLDL receptor (HD-Ad-VLDLR) under control of a liver-selective promoter. Treatment with HD-Ad-VLDLR together with a low-fat diet regimen resulted in reduced lesion size (cross-sectional area decreased from 146,272 +/- 19,359 to 91,557 +/- 15,738 microm2) and an 89% reduction in the cross-sectional lesion area occupied by macrophages compared to controls. These results show that aggressive VLDL/LDL lowering achieved by hepatic overexpression of VLDLR combined with a low-fat diet regimen induces regression of advanced plaques in the brachiocephalic artery of LDL receptor-deficient mice.