Sterile inflammation induces vasculopathy and chronic lung injury in murine sickle cell disease

Murine sickle cell disease (SCD) results in damage to multiple organs, likely mediated first by vasculopathy. While the mechanisms inducing vascular damage remain to be determined, nitric oxide bioavailability and sterile inflammation are both considered to play major roles in vasculopathy. Here, we investigate the effects of high mobility group box-1 (HMGB1), a pro-inflammatory damage-associated molecular pattern (DAMP) molecule on endothelial-dependent vasodilation and lung morphometrics, a structural index of damage in sickle (SS) mice. SS mice were treated with either phosphate-buffered saline (PBS), hE-HMGB1-BP, an hE dual-domain peptide that binds and removes HMGB1 from the circulation via the liver, 1-[4-(aminocarbonyl)-2-methylphenyl]-5-[4-(1H-imidazol-1-yl)phenyl]-1H-pyrrole-2-propanoic acid (N6022) or N-acetyl-lysyltyrosylcysteine amide (KYC) for three weeks. Human umbilical vein endothelial cells (HUVEC) were treated with recombinant HMGB1 (r-HMGB1), which increases S-nitrosoglutathione reductase (GSNOR) expression by ∼80%, demonstrating a direct effect of HMGB1 to increase GSNOR. Treatment of SS mice with hE-HMGB1-BP reduced plasma HMGB1 in SS mice to control levels and reduced GSNOR expression in facialis arteries isolated from SS mice by ∼20%. These changes were associated with improved endothelial-dependent vasodilation. Treatment of SS mice with N6022 also improved vasodilation in SS mice suggesting that targeting GSNOR also improves vasodilation. SCD decreased protein nitrosothiols (SNOs) and radial alveolar counts (RAC) and increased GSNOR expression and mean linear intercepts (MLI) in lungs from SS mice. The marked changes in pulmonary morphometrics and GSNOR expression throughout the lung parenchyma in SS mice were improved by treating with either hE-HMGB1-BP or KYC. These data demonstrate that murine SCD induces vasculopathy and chronic lung disease by an HMGB1- and GSNOR-dependent mechanism and suggest that HMGB1 and GSNOR might be effective therapeutic targets for reducing vasculopathy and chronic lung disease in humans with SCD.

Vasodilation of Isolated Vessels and the Isolation of the Extracellular Matrix of Tight-skin Mice

The interferon regulatory factor 5 (IRF5) is crucial for cells to determine if they respond in a pro-inflammatory or anti-inflammatory fashion. IRF5's ability to switch cells from one pathway to another is highly attractive as a therapeutic target. We designed a decoy peptide IRF5D with a molecular modeling software for designing small molecules and peptides. IRF5D inhibited IRF5, reduced alterations in extracellular matrix, and improved endothelial vasodilation in the tight-skin mouse (Tsk/+). The Kd of IRF5D for recombinant IRF5 is 3.72 ± 0.74 x 10^-6 M as determined by binding experiments using biolayer interferometry experiments. Endothelial cells (EC) proliferation and apoptosis were unchanged using increasing concentrations of IRF5D (0 to 100 µg/mL, 24 h). Tsk/+ mice were treated with IRF5D (1 mg/kg/d subcutaneously, 21 d). IRF5 and ICAM expressions were decreased after IRF5D treatment. Endothelial function was improved as assessed by vasodilation of facialis arteries from Tsk/+ mice treated with IRF5D compared to Tsk/+ mice without IRF5D treatment. As a transcription factor, IRF5 traffics from the cytosol to the nucleus. Translocation was assessed by immunohistochemistry on cardiac myocytes cultured on the different cardiac extracellular matrices. IRF5D treatment of the Tsk/+ mouse resulted in a reduced number of IRF5 positive nuclei in comparison to the animals without IRF5D treatment (50 µg/mL, 24 h). These findings demonstrate the important role that IRF5 plays in inflammation and fibrosis in Tsk/+ mice.

Inhibition of myeloperoxidase oxidant production by N-acetyl lysyltyrosylcysteine amide reduces brain damage in a murine model of stroke

BACKGROUND

Oxidative stress plays an important and causal role in the mechanisms by which ischemia/reperfusion (I/R) injury increases brain damage after stroke. Accordingly, reducing oxidative stress has been proposed as a therapeutic strategy for limiting damage in the brain after stroke. Myeloperoxidase (MPO) is a highly potent oxidative enzyme that is capable of inducing both oxidative and nitrosative stress in vivo.

METHODS

To determine if and the extent to which MPO-generated oxidants contribute to brain I/R injury, we treated mice subjected to middle cerebral artery occlusion (MCAO) with N-acetyl lysyltyrosylcysteine amide (KYC), a novel, specific and non-toxic inhibitor of MPO. Behavioral testing, ischemic damage, blood-brain-barrier disruption, apoptosis, neutrophils infiltration, microglia/macrophage activation, and MPO oxidation were analyzed within a 7-day period after MCAO.

RESULTS

Our studies show that KYC treatment significantly reduces neurological severity scores, infarct size, IgG extravasation, neutrophil infiltration, loss of neurons, apoptosis, and microglia/macrophage activation in the brains of MCAO mice. Immunofluorescence studies show that KYC treatment reduces the formation of chlorotyrosine (ClTyr), a fingerprint biomarker of MPO oxidation, nitrotyrosine (NO2Tyr), and 4-hydroxynonenal (4HNE) in MCAO mice. All oxidative products colocalized with MPO in the infarcted brains, suggesting that MPO-generated oxidants are involved in forming the oxidative products.

CONCLUSIONS

MPO-generated oxidants play detrimental roles in causing brain damage after stroke which is effectively reduced by KYC.

An IRF5 Decoy Peptide Reduces Myocardial Inflammation and Fibrosis and Improves Endothelial Cell Function in Tight-Skin Mice

Interferon regulatory factor 5 (IRF5) has been called a "master switch" for its ability to determine whether cells mount proinflammatory or anti-inflammatory responses. Accordingly, IRF5 should be an attractive target for therapeutic drug development. Here we report on the development of a novel decoy peptide inhibitor of IRF5 that decreases myocardial inflammation and improves vascular endothelial cell (EC) function in tight-skin (Tsk/+) mice. Biolayer interferometry studies showed the Kd of IRF5D for recombinant IRF5 to be 3.72 ± 0.74x10-6M. Increasing concentrations of IRF5D (0-100 μg/mL, 24h) had no significant effect on EC proliferation or apoptosis. Treatment of Tsk/+ mice with IRF5D (1mg/kg/d subcutaneously, 21d) reduced IRF5 and ICAM-1 expression and monocyte/macrophage and neutrophil counts in Tsk/+ hearts compared to expression in hearts from PBS-treated Tsk/+ mice (p<0.05). EC-dependent vasodilatation of facialis arteries isolated from PBS-treated Tsk/+ mice was reduced (~15%). IRF5D treatments (1mg/kg/d, 21d) improved vasodilatation in arteries isolated from Tsk/+ mice nearly 3-fold (~45%, p<0.05), representing nearly 83% of the vasodilatation in arteries isolated from C57Bl/6J mice (~55%). IRF5D (50μg/mL, 24h) reduced nuclear translocation of IRF5 in myocytes cultured on both Tsk/+ cardiac matrix and C57Bl/6J cardiac matrix (p<0.05). These data suggest that IRF5 plays a causal role in inflammation, fibrosis and impaired vascular EC function in Tsk/+ mice and that treatment with IRF5D effectively counters IRF5-dependent mechanisms of inflammation and fibrosis in the myocardium in these mice.

Abstract 294: Inhibiting Myeloperoxidase Restores Collateralization in Ischemic Hindlimbs in Diabetes

Background: Myeloperoxidase (MPO) is released from activated neutrophils and is believed to play a causal role in peripheral vascular disease (PVD). Leptin receptor deficient (db/db) mice are a model of type 2 diabetes mellitus (DM) that are regularly used to investigate mechanisms by which DM impairs endothelial cell (EC) function and increases PVD.

Objectives and Methods: To investigate MPO’s role in ischemic disease in DM, db/db mice were pretreated with N-acetyl-lysyltyrosylcysteine amine (KYC, subQ, 1 mg/kd/d) for 7 days, subjected to hindlimb ischemia, treated with KYC for 14 days and changes in blood flow determined by Laser Doppler. Hindlimbs were examined for changes in neutrophil counts, chlorotyrosine (Cl-Tyr), 4-hydroxynoneal (4-HNE), advanced glycation end-products (AGE) expression via immunohistochemistry and immunoblotting. Hindlimb matrix was used to determine the effects of DM and KYC treatments on matrix-dependent EC proliferation and migration.

Results: Percent change in blood flow in ischemic legs (IL) of C57BL/6J mice increased to ~50% by day 14 post femoral artery ligation compared to day 0. In contrast, blood flow in IL of untreated db/db mice increased to ~13%, ~15% and ~17% on days 3, 7 and 14. Blood flow in IL of db/db mice treated with KYC increased to ~20%, ~43% and ~47% on days 3, 7 and 14. KYC treatments decreased neutrophil counts, Cl-Tyr, 4-HNE and AGE expression in IL. Further, proliferation and migration were increased when EC were cultured on matrix isolated from KYC-treated db/db mice compared to matrix from untreated db/db mice. Interestingly, KYC treatments had no effect on blood glucose in db/db mice.

Conclusions: MPO increases oxidative stress, tissue injury and impairs EC function to increase PVD in db/db mice. KYC inhibition of MPO reduces oxidative stress and tissue injury and restores EC function and blood flow in db/db mice. These data suggest that KYC may be effective for treating PVD in patients with diabetes.

Inhibition of myeloperoxidase decreases vascular oxidative stress and increases vasodilatation in sickle cell disease mice

Activated leukocytes and polymorphonuclear neutrophils (PMN) release myeloperoxidase (MPO), which binds to endothelial cells (EC), is translocated, and generates oxidants that scavenge nitric oxide (NO) and impair EC function. To determine whether MPO impairs EC function in sickle cell disease (SCD), control (AA) and SCD mice were treated with N-acetyl-lysyltyrosylcysteine-amide (KYC). SCD humans and mice have high plasma MPO and soluble L-selectin (sL-selectin). KYC had no effect on MPO but decreased plasma sL-selectin and malondialdehyde in SCD mice. MPO and 3-chlorotyrosine (3-ClTyr) were increased in SCD aortas. KYC decreased MPO and 3-ClTyr in SCD aortas to the levels in AA aortas. Vasodilatation in SCD mice was impaired. KYC increased vasodilatation in SCD mice more than 2-fold, to ∼60% of levels in AA mice. KYC inhibited MPO-dependent 3-ClTyr formation in EC proteins. SCD mice had high plasma alanine transaminase (ALT), which tended to decrease in KYC-treated SCD mice (P = 0.07). KYC increased MPO and XO/XDH and decreased 3-ClTyr and 3-nitrotyrosine (3-NO₂Tyr) in SCD livers. These data support the hypothesis that SCD increases release of MPO, which generates oxidants that impair EC function and injure livers. Inhibiting MPO is an effective strategy for decreasing oxidative stress and liver injury and restoring EC function in SCD.

N-acetyl lysyltyrosylcysteine amide inhibits myeloperoxidase, a novel tripeptide inhibitor

Myeloperoxidase (MPO) plays important roles in disease by increasing oxidative and nitrosative stress and oxidizing lipoproteins. Here we report N-acetyl lysyltyrosylcysteine amide (KYC) is an effective inhibitor of MPO activity. We show KYC inhibits MPO-mediated hypochlorous acid (HOCl) formation and nitration/oxidation of LDL. Disulfide is the major product of MPO-mediated KYC oxidation. KYC (≤4,000 μM) does not induce cytotoxicity in bovine aortic endothelial cells (BAECs). KYC inhibits HOCl generation by phorbol myristate acetate (PMA)-stimulated neutrophils and human promyelocytic leukemia (HL-60) cells but not superoxide generation by PMA-stimulated HL-60 cells. KYC inhibits MPO-mediated HOCl formation in BAEC culture and protects BAECs from MPO-induced injury. KYC inhibits MPO-mediated lipid peroxidation of LDL whereas tyrosine (Tyr) and tryptophan (Trp) enhance oxidation. KYC is unique as its isomers do not inhibit MPO activity, or are much less effective. Ultraviolet-visible spectral studies indicate KYC binds to the active site of MPO and reacts with compounds I and II. Docking studies show the Tyr of KYC rests just above the heme of MPO. Interestingly, KYC increases MPO-dependent H₂O₂ consumption. These data indicate KYC is a novel and specific inhibitor of MPO activity that is nontoxic to endothelial cell cultures. Accordingly, KYC may be useful for treating MPO-mediated vascular disease.

Transient repetitive exposure to low level light therapy enhances collateral blood vessel growth in the ischemic hindlimb of the tight skin mouse

The tight skin mouse (Tsk(-/+)) is a model of scleroderma characterized by impaired vasoreactivity, increased oxidative stress, attenuated angiogenic response to VEGF and production of the angiogenesis inhibitor angiostatin. Low-level light therapy (LLLT) stimulates angiogenesis in myocardial infarction and chemotherapy-induced mucositis. We hypothesize that repetitive LLLT restores vessel growth in the ischemic hindlimb of Tsk(-/+) mice by attenuating angiostatin and enhancing angiomotin effects in vivo. C57Bl/6J and Tsk(-/+) mice underwent ligation of the femoral artery. Relative blood flow to the foot was measured using a laser Doppler imager. Tsk(-/+) mice received LLLT (670 nm, 50 mW cm(-2), 30 J cm(-2)) for 10 min per day for 14 days. Vascular density was determined using lycopersicom lectin staining. Immunofluorescent labeling, Western blot analysis and immunoprecipitation were used to determine angiostatin and angiomotin expression. Recovery of blood flow to the ischemic limb was reduced in Tsk(-/+) compared with C57Bl/6 mice 2 weeks after surgery. LLLT treatment of Tsk(-/+) mice restored blood flow to levels observed in C57Bl/6 mice. Vascular density was decreased, angiostatin expression was enhanced and angiomotin depressed in the ischemic hindlimb of Tsk(-/+) mice. LLLT treatment reversed these abnormalities. LLLT stimulates angiogenesis by increasing angiomotin and decreasing angiostatin expression in the ischemic hindlimb of Tsk(-/+) mice.

4F decreases IRF5 expression and activation in hearts of tight skin mice

The apoAI mimetic 4F was designed to inhibit atherosclerosis by improving HDL. We reported that treating tight skin (Tsk^−/+) mice, a model of systemic sclerosis (SSc), with 4F decreases inflammation and restores angiogenic potential in Tsk^−/+ hearts. Interferon regulating factor 5 (IRF5) is important in autoimmunity and apoptosis in immune cells. However, no studies were performed investigating IRF5 in myocardium. We hypothesize that 4F differentially modulates IRF5 expression and activation in Tsk^−/+ hearts. Posterior wall thickness was significantly increased in Tsk^−/+ compared to C57Bl/6J (control) and Tsk^−/+ mice with 4F treatment assessed by echoradiography highlighting reduction of fibrosis in 4F treated Tsk^−/+ mice. IRF5 in heart lysates from control and Tsk/+ with and without 4F treatment (sc, 1 mg/kg/d, 6–8 weeks) was determined. Phosphoserine, ubiquitin, ubiquitin K⁶³ on IRF5 were determined on immunoprecipitates of IRF5. Immunofluorescence and TUNEL assays in heart sections were used to determine positive nuclei for IRF5 and apoptosis, respectively. Fluorescence-labeled streptavidin (SA) was used to determine endothelial cell uptake of biotinylated 4F. SA-agarose pulldown and immunoblotting for IRF5 were used to determine 4F binding IRF5 in endothelial cell cytosolic fractions and to confirm biolayer interferometry studies. IRF5 levels in Tsk^−/+ hearts were similar to control. 4F treatments decrease IRF5 in Tsk^−/+ hearts and decrease phosphoserine and ubiquitin K⁶³ but increase total ubiquitin on IRF5 in Tsk^−/+ compared with levels on IRF5 in control hearts. 4F binds IRF5 by mechanisms favoring association over dissociation strong enough to pull down IRF5 from a mixture of endothelial cell cytosolic proteins. IRF5 positive nuclei and apoptotic cells in Tsk^−/+ hearts were increased compared with controls. 4F treatments decreased both measurements in Tsk^−/+ hearts. IRF5 activation in Tsk^−/+ hearts is increased. 4F treatments decrease IRF5 expression and activation in Tsk^−/+ hearts by a mechanism related to 4F’s ability to bind IRF5.

A novel hemoglobin-binding peptide reduces cell-free hemoglobin in murine hemolytic anemia

Hemolysis can saturate the hemoglobin (Hb)/heme scavenging system, resulting in increased circulating cell-free Hb (CF-Hb) in hereditary and acquired hemolytic disease. While recent studies have suggested a central role for intravascular hemolysis and CF-Hb in the development of vascular dysfunction, this concept has stimulated considerable debate. This highlights the importance of determining the contribution of CF-Hb to vascular complications associated with hemolysis. Therefore, a novel Hb-binding peptide was synthesized and linked to a small fragment of apolipoprotein E (amino acids 141-150) to facilitate endocytic clearance. Plasma clearance of hE-Hb-b10 displayed a rapid phase t(1/2) of 16 min and slow phase t(1/2) of 10 h, trafficking primarily through the liver. Peptide hE-Hb-B10 decreased CF-Hb in mice treated with phenylhydrazine, a model of acute hemolysis. Administration of hE-Hb-B10 also attenuated CF-Hb in two models of chronic hemolysis: Berkeley sickle cell disease (SS) mice and mice with severe hereditary spherocytosis (HS). The hemolytic rate was unaltered in either chronic hemolysis model, supporting the conclusion that hE-Hb-B10 promotes CF-Hb clearance without affecting erythrocyte lysis. Interestingly, hE-Hb-B10 also decreased plasma ALT activity in SS and HS mice. Although acetylcholine-mediated facialis artery vasodilation was not improved by hE-Hb-B10 treatment, the peptide shifted vascular response in favor of NO-dependent vasodilation in SS mice. Taken together, these data demonstrate that hE-Hb-B10 decreases CF-Hb with a concomitant reduction in liver injury and changes in vascular response. Therefore, hE-Hb-B10 can be used to investigate the different roles of CF-Hb in hemolytic pathology and may have therapeutic benefit in the treatment of CF-Hb-mediated tissue damage.

Abnormal fibrillin-1 expression and chronic oxidative stress mediate endothelial mesenchymal transition in a murine model of systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune connective tissue disorder characterized by oxidative stress, impaired vascular function, and attenuated angiogenesis. The tight-skin (Tsk(-/+)) mouse is a model of SSc that displays many of the cellular features of the clinical disease. We tested the hypotheses that abnormal fibrillin-1 expression and chronic phospholipid oxidation occur in Tsk(-/+) mice and, furthermore, that these factors precipitate a prooxidant state, collagen-related protein expression, apoptosis, and mesenchymal transition in endothelial cells cultured on Tsk(-/+) extracellular matrix. Human umbilical vein endothelial cells were seeded on microfibrils isolated from skin of C57BL/6J (control) and Tsk(-/+) mice in the presence or absence of chronic pretreatment with the apolipoprotein Apo A-I mimetic D-4F (1 mg·kg(-1)·day(-1) ip for 6 to 8 wk). Nitric oxide-to-superoxide anion ratio was assessed 12 h after culture, and cell proliferation, apoptosis, and phenotype were studied 72 h after culture. Tsk(-/+) mice demonstrated abnormal "big fibrillin" expression (405 kDa) by Western blot analysis compared with control. Endothelial cells cultured on microfibrils prepared from Tsk(-/+) mice demonstrated reduced proliferation, a prooxidant state (reduced nitric oxide-to-superoxide anion ratio), increased apoptosis, and collagen-related protein expression associated with mesenchymal transition. Chronic D-4F pretreatment of Tsk(-/+) mice attenuated many of these adverse effects. The findings demonstrate that abnormal fibrillin-1 expression and chronic oxidative stress mediate endothelial mesenchymal transition in Tsk(-/+) mice. This mesenchymal transition may contribute to the reduction in angiogenesis that is known to occur in this model of SSc.

Genetic deletion of apolipoprotein A-I increases airway hyperresponsiveness, inflammation, and collagen deposition in the lung

The relationship between high-density lipoprotein and pulmonary function is unclear. To determine mechanistic relationships we investigated the effects of genetic deletion of apolipoprotein A-I (apoA-I) on plasma lipids, paraoxonase (PON1), pro-inflammatory HDL (p-HDL), vasodilatation, airway hyperresponsiveness and pulmonary oxidative stress, and inflammation. ApoA-I null (apoA-I(-/-)) mice had reduced total and HDL cholesterol but increased pro-inflammatory HDL compared with C57BL/6J mice. Although PON1 protein was increased in apoA-I(-/-) mice, PON1 activity was decreased. ApoA-I deficiency did not alter vasodilatation of facialis arteries, but it did alter relaxation responses of pulmonary arteries. Central airway resistance was unaltered. However, airway resistance mediated by tissue dampening and elastance were increased in apoA-I(-/-) mice, a finding also confirmed by positive end-expiratory pressure (PEEP) studies. Inflammatory cells, collagen deposition, 3-nitrotyrosine, and 4-hydroxy-2-nonenal were increased in apoA-I(-/-) lungs but not oxidized phospholipids. Colocalization of 4-hydroxy-2-nonenal with transforming growth factor beta-1 (TGFbeta-1 was increased in apoA-I(-/-) lungs. Xanthine oxidase, myeloperoxidase and endothelial nitric oxide synthase were increased in apoA-I(-/-) lungs. Dichlorodihydrofluorescein-detectable oxidants were increased in bronchoalveolar lavage fluid (BALF) in apoA-I(-/-) mice. In contrast, BALF nitrite+nitrate levels were decreased in apoA-I(-/-) mice. These data demonstrate that apoA-I plays important roles in limiting pulmonary inflammation and oxidative stress, which if not prevented, will decrease pulmonary artery vasodilatation and increase airway hyperresponsiveness.

A strength-endurance index for power grip

INTRODUCTION

The purpose of this study was to quantify muscle strength and endurance in power grip.

METHOD

Workers (74 M and 74 F, 18-72 years) squeezed a dynamometer for a 60 s, 18-cycle test. Initial strength (IS) and final strength (FS) were calculated as the mean peak force for cycles 1-3 and 16-18, respectively. Endurance was defined by the strength decrement index (SDI) where SDI = (IS - FS)/IS x 100. A grip strength-endurance analyzer was constructed from IS and SDI data which were depicted on two parallel, linearly scaled axes. Discrete IS and SDI scores were connected on each axis with a vector. The vector (Vmag) was measured directly from the analyzer and its direction identified from its slope. Integer scales transformed discrete IS and SDI scores into individual strength-endurance performance scores (SEPS).

RESULTS

Better than 95% of the sample (n > or = 141) scored within acceptable test ranges defined as the combined sample mean +/- 2SD, for SDI, Vmag and SEPS. Vmag was the best predictor for SEPS. Linear regression for SEPS was SEPS (combined) = 0.09 (Vmag) - 0.29: (SEE = 0.829). The analyzer revealed individual scores outside acceptable ranges for injured and uninjured efforts.

CONCLUSION

The development of a power grip strength-endurance analyzer provided a simple method to graph individual power grip performances. Converting strength and endurance scores to integers and summing them (SEPS) provided a simple means to represent individual estimates of power grip strength-endurance performance.

Effects of D-4F on vasodilation, oxidative stress, angiostatin, myocardial inflammation, and angiogenic potential in tight-skin mice

Systemic sclerosis (scleroderma, SSc) is an autoimmune, connective tissue disorder that is characterized by impaired vascular function, increased oxidative stress, inflammation of internal organs, and impaired angiogenesis. Tight skin mice (Tsk−/+) have a defect in fibrillin-1, resulting in replication of many of the myocardial and vascular features seen in humans with SSc. D-4F is an apolipoprotein A-I (apoA-I) mimetic that improves vascular function in diverse diseases such as hypercholesterolemia, influenza, and sickle cell disease. Tsk−/+ mice were treated with either phosphate-buffered saline (PBS) or D-4F (1 mg·kg−1·day−1 for 6–8 wk). Acetylcholine and flow-induced vasodilation were examined in facialis arteries. Proinflammatory HDL (p-HDL) in murine and human plasma samples was determined by the cell-free assay. Angiostatin levels in murine and human plasma samples were determined by Western blot analysis. Hearts were examined for changes in angiostatin and autoantibodies against oxidized phosphotidylcholine (ox-PC). Angiogenic potential in thin sections of murine hearts was assessed by an in vitro vascular endothelial growth factor (VEGF)-induced endothelial cell (EC) tube formation assay. D-4F improved endothelium-, endothelial nitric oxide synthase-dependent, and flow-mediated vasodilation in Tsk−/+ mice. Tsk−/+ mice had higher plasma p-HDL and angiostatin levels than C57BL/6 mice, as did SSc patients compared with healthy control subjects. Tsk−/+ mice also had higher triglycerides than C57BL/6 mice. D-4F reduced p-HDL, angiostatin, and triglycerides in the plasma of Tsk−/+ mice. Tsk−/+ hearts contained notably higher levels of angiostatin and autoantibodies against ox-PC than those of control hearts. D-4F ablated angiostatin in Tsk−/+ hearts and reduced autoantibodies against ox-PC by >50% when compared with hearts from untreated Tsk−/+ mice. Angiogenic potential in Tsk−/+ hearts was increased only when the Tsk−/+ mice were treated with D-4F (1 mg·kg−1·day−1, 6–8 wk), and cultured sections of hearts from the D-4F-treated Tsk−/+ micewere incubated with D-4F (10 μg/ml, 5–7 days). Failure to treat the thin sections of hearts and Tsk−/+ mice with D-4F resulted in loss of VEGF-induced EC tube formation. D-4F improves vascular function, decreases myocardial inflammation, and restores angiogenic potential in the hearts of Tsk−/+ mice. As SSc patients have increased plasma p-HDL and angiostatin levels similar to the Tsk−/+ mice, D-4F may be effective at treating vascular complications in patients with SSc.

Endothelium-derived microparticles induce endothelial dysfunction and acute lung injury

Acute lung injury (ALI) carries a high mortality in critically ill patients. Recent reports correlate elevated concentrations of endothelium-derived microparticles (EMPs) with diseases of endothelial dysfunction. Many of these diseases have ALI sequelae. We hypothesize that EMPs contribute to endothelial cell (EC) dysfunction and development of ALI. To test this hypothesis, we treated isolated vessels with EMPs and examined changes in vasodilation. Endothelial cell cultures were incubated with EMPs and examined for changes in stimulated nitric oxide (*NO) production and nitric oxide synthase (eNOS) activation. Finally, EMPs were injected into rats and mice and lungs examined for ALI. In both mouse and human ex vivo vessel preparations, we found a marked attenuation of endothelium-mediated vasodilation after EMP treatment (4 x 10(6)/mL). This dysfunction was not corrected by pretreatment of EMPs with free radical scavengers. Coincubation of EMPs with EC cultures yielded a three-fold reduction in A23187-stimulated *NO release. Western analysis of these cells showed a corresponding decrease in eNOS phosphorylation at Ser1179 and a decrease in hsp90 association. Measurements of lung permeability, myeloperoxidase activity, and histology of EMPs-treated Brown Norway rats demonstrated pulmonary edema, neutrophil recruitment, and compromise of the endothelial-alveolar barrier as a second hit phenomenon. In C57BL/6 mice, exogenous EMPs caused a significant rise in pulmonary capillary permeability both as a primary and secondary injury. These findings demonstrate EMPs are capable of inducing significant lung injury at pathophysiologically relevant concentrations. Endothelium-derived microparticles inhibit endothelium-mediated vasodilation and *NO generation from eNOS. Once elucidated, EMP mechanisms of inducing ALI and endothelial dysfunction may present new therapeutic targets.

Development of explicit criteria to measure adherence to hypertension guidelines

Measures of adherence to hypertension guidelines have historically been based on prescription data or physician survey data regarding treatment practices. These methods have limitations that decrease their accuracy. As part of a randomized controlled study testing the effects of pharmacist/physician collaboration on adherence to hypertension guidelines, the investigators and an expert panel developed a JNC 7 measurement tool. The final guideline adherence measurement tool includes 22 explicit criteria in four domains of care. An exploratory factor analysis, conducted to assess the structure of the tool, suggests three underlying treatment dimensions in hypertension care. The adherence measurement tool will allow researchers to link specific elements of care to improved blood pressure control. In addition, use of the tool will provide clinicians with a taxonomy for evaluating practice and describing the effect of improved patient care on patient outcomes.

Cardiovascular disease risk factors in habitual exercisers, lean sedentary men and abdominally obese sedentary men

OBJECTIVE

To investigate whether the favourable cardiovascular disease (CVD) risk factor profile of habitual exercisers is attributable to exercise or leanness.

DESIGN

Cross-sectional study of 113 nonsmoking men aged 30-45 y. CVD risk factors were compared in exercisers (n=39) and sedentary men (n=74), and in subgroups of lean exercisers (n=37), lean sedentary men (n=46) and obese sedentary men (n=28). Waist girth was used to identify lean (<100 cm) and abdominally obese (> or =100 cm) subgroups.

MEASUREMENTS

Blood pressure, physical activity (7-day recall), physical fitness (maximum oxygen consumption) and fasted lipoproteins, apolipoprotein (apo) B, triglycerides, glucose and fibrinogen.

RESULTS

Exercisers were fitter and leaner than sedentary men and had a better CVD risk factor profile. Total cholesterol, LDL-cholesterol and apo B concentrations were lower in lean exercisers than in lean sedentary men, suggesting that exercise influences these risk factors. Indeed, time spent in vigorous activity was the only significant predictor of total cholesterol and LDL-cholesterol in multiple linear regression models. Exercise status had little influence on triglycerides and HDL-cholesterol (HDL-C), and unfavourable levels were only evident among obese sedentary men. Waist girth was the sole predictor of triglycerides and HDL-C, explaining 44 and 31% of the variance, respectively.

CONCLUSIONS

These findings suggest that the CVD risk factor profile of habitual exercisers is attributable to leanness and exercise. Leanness is associated with favourable levels of HDL-C and triglycerides, while exercise is associated with lower levels of total cholesterol, LDL-cholesterol and apo B.

Urokinase induced fibrinolysis in thromboelastography: a model for studying fibrinolysis and coagulation in whole blood

BACKGROUND

The contact system (CS) proteins, factor XII and prekallikrein are thought to have roles in blood coagulation and fibrinolysis. Recent research has suggested that the CS proteins might be more important in fibrinolysis and cell function than in coagulation. Most studies on fibrinolysis have used plasma or euglobulin assays, ignoring the influence of cellular elements of blood on the fibrinolytic process.

OBJECTIVE AND METHODS

In order to study both coagulation and fibrinolysis in whole blood (WB), we have developed a thromboelastography (TEG) assay to investigate both coagulation and fibrinolysis in the same blood sample. In this assay, named urokinase (UK) induced fibrinolysis in thromboelastography (UKIFTEG), TEG is performed on recalcified citrated WB in the presence of UK. Large variations in Ly60 (percentage lysis 60 min after clot formation) were obtained between different donors with the same UK concentration. The UKIFTEG assay was therefore performed using UK concentrations that gave Ly60 values in the approximate range of 20-40%.

RESULTS

The effect of CS activation was investigated in the presence or absence of celite (10 mg mL(-1) blood). Celite shortened the clotting time (CT), and increased Ly60 values. Factor XIIa (FXIIa) and plasma kallikrein (KK) produced concentration dependent reductions in CT (significant at concentrations of 1303 and 2600 ng mL(-1) blood, respectively) and increased Ly60 values (significant at concentrations of 652 and 1300 ng mL(-1) blood, respectively).

CONCLUSIONS

Our results show that CS activation and both FXIIa and KK produce reductions in clotting time and enhanced fibrinolysis in UKIFTEG.

Effects of D-4F on vasodilation and vessel wall thickness in hypercholesterolemic LDL receptor-null and LDL receptor/apolipoprotein A-I double-knockout mice on Western diet

Previously we showed L-4F, a novel apolipoprotein A-I (apoA-I) mimetic, improved vasodilation in 2 dissimilar models of vascular disease: hypercholesterolemic LDL receptor-null (Ldlr(-/-)) mice and transgenic sickle cell disease mice. Here we determine the mechanisms by which D-4F improves vasodilation and arterial wall thickness in hypercholesterolemic Ldlr(-/-) mice and Ldlr(-/-)/apoA-I null (apoA-I(-/-)), double-knockout mice. Ldlr(-/-) and Ldlr(-/-)/apoA-I(-/-) mice were fed Western diet (WD) with and without D-4F. Oral D-4F restored endothelium- and endothelial NO synthase (eNOS)-dependent vasodilation in direct relationship to duration of treatments and reduced wall thickness in as little as 2 weeks in vessels with preexisting disease in Ldlr(-/-) mice. D-4F had no effect on total or HDL cholesterol concentrations but reduced proinflammatory HDL levels. D-4F had no effect on plasma myeloperoxidase concentrations but reduced myeloperoxidase association with apoA-I as well as 3-nitrotyrosine in apoA-I. D-4F increased endothelium- and eNOS-dependent vasodilation in Ldlr(-/-)/apoA-I(-/-) mice but did not reduce wall thickness as it had in Ldlr(-/-) mice. Vascular endothelial cells were treated with 22(R)-hydroxycholesterol with and without L-4F. 22(R)-Hydroxycholesterol decreased NO (*NO) and increased superoxide anion (O2*-) production and increased ATP-binding cassette transporter-1 and collagen expression. L-4F restored *NO and O2*- balance, had little effect on ATP-binding cassette transporter-1 expression, but reduced collagen expression. These data demonstrate that although D-4F restores vascular endothelial cell and eNOS function to increase vasodilation, HDL containing apoA-I, or at least some critical concentration of the antiatherogenic lipoprotein, is required for D-4F to decrease vessel wall thickness.

The antigenic binding site(s) of antibodies to factor XII associated with the antiphospholipid syndrome

Phospholipid binding proteins, including factor XII (FXII), are known to be targeted by antiphospholipid antibodies (aPA). Factor XII antibodies (FXIIab) have been described in some patients with the antiphospholipid syndrome (APS) and have been shown to lead to reduced levels of FXII. The antigenic binding site(s) and the pathophysiological effects of FXIIab are unknown. In an attempt to elucidate the binding site of these antibodies, immobilized plasma kallikrein was used to cleave FXII into its 52-kDa heavy-chain (HCFXII) and 28-kDa light-chain (LCFXII) components. Plasma samples from 12 female patients with definite APS and FXIIab were investigated for the presence of antibodies to FXII, HCFXII and LCFXII. All but one patient's plasma reacted to FXII, HCFXII and LCFXII in a similar manner. One patient gave markedly reduced positivity to HCFXII and LCFXII, suggesting that the FXIIab in this patient had a higher affinity for the intact FXII molecule. To further investigate the antigenic binding site(s) of FXII, 150 biotinylated peptides of the known FXII sequence were synthesized using a Multipin(TM) peptide synthesis procedure. The IgG and IgM fractions of the 12 patients' plasma were purified by affinity chromatography. The synthesized peptides were captured on streptavidin plates and individual patients' purified FXIIab assayed against the peptides in a modified enzyme-linked immunosorbent assay (ELISA). Two regions were identified as possible antigenic binding site(s) for FXIIab: one in the growth factor domain and the other in the catalytic domain.

Putting dental mercury pollution into perspective

This paper deals with the issue of amalgam waste from dental offices. The aim is to put into perspective the very small contribution of dental mercury to the overall volume of mercury discharged into the environment each year. While the amount discharged from dental offices is very small compared to other sources, the amount discharged into the environment from amalgam fillings in people's mouths is estimated as less than 2% of the amount from dental offices. At least 50% of mercury in the environment comes from natural sources. The major source of man-made mercury pollution is the industrial burning of fossil fuels. It is important to distinguish between inorganic mercury and organic mercury in terms of the impact on the health of the population.

Mechanical properties of commercial high strength ceramic core materials

OBJECTIVE

The objective of the present study is to evaluate and compare the flexural strength, dynamic elastic moduli and true hardness (H(o)) values of commercial Vita In-Ceram alumina core and Vita In-Ceram matrix glass with the standard aluminous porcelain (Hi-Ceram and Vitadur), Vitadur N and Dicor glass and glass-ceramic.

METHODS

The flexural strength was evaluated (n=5) using 3-point loading and a servo hydraulic Instron testing machine at a cross head speed of 0.5 mm/min. The density of the specimens (n=3) was measured by means of the water displacement technique. Dynamic Young's shear and bulk moduli and Poisson's ratio (n=3) were measured using a non-destructive ultrasonic technique using 10 MHz lithium niobate crystals. The true hardness (n=3) was measured using a Knoop indenter and the fracture toughness (n=3) was determined using a Vickers indenter and a Tukon hardness tester. Statistical analysis of the data was conducted using ANOVA and a Student-Newman-Keuls (SNK) rank order multiple comparative test.

RESULTS

The SNK rank order test analysis of the mean flexural strength was able to separate five commercial core materials into three significant groups at p=0.05. Vita In-Ceram alumina and IPS Empress 2 exhibited significantly higher flexural strength than aluminous porcelains and IPS Empress at p=0.05. The dynamic elastic moduli and true hardness of Vita In-Ceram alumina core were significantly higher than the rest of the commercial ceramic core materials at p=0.05.

SIGNIFICANCE

The ultrasonic test method is a valuable mechanical characterization tool and was able to statistically discriminate between the chemical and structural differences within dental ceramic materials. Significant correlation was obtained between the dynamic Young's modulus and true hardness, p=0.05.

Depletion and restoration of endogenous monoamines affects β-CIT binding to serotonin but not dopamine transporters in non-human primates

The radioligand [123I]beta-CIT binds to dopamine transporters in striatum and to serotonin transporters in brainstem. Endogenous dopamine or serotonin may compete with radioligand binding at monoamine transporters. We used alpha-methyl-p-tyrosine (AMPT) to block dopamine production and measured [123I]beta-CIT binding before and after endogenous dopamine was restored by IV administration of the dopamine precursor L-dihydroxyphenylalanine (L-DOPA) in rhesus monkeys. P-chlorophenylalanine (pCPA) was used to inhibit serotonin production, and [123I]beta-CIT binding was assessed before and after IV administration of the serotonin precursor 5-hydroxy-L-tryptophan (L-5-HTP) restored endogenous serotonin. Pretreatment with benserazide blocked peripheral decarboxylization in both paradigms. Serotonin restoration measurably displaced [123I]beta-CIT binding to brainstem serotonin transporters but not to striatal dopamine transporters. Restoration of dopamine apparently did not affect [123I] beta-CIT binding to striatal dopamine transporters. However, dopamine restoration reduced radioligand binding to brainstem serotonin transporters, most likely due to dopamine release from serotonin neurons following L-DOPA administration. The higher striatal density of dopamine transporters relative to dopamine concentrations may explain why [123I] beta-CIT displacement by endogenous dopamine was not observed. This study indicates that [123I]beta-CIT binding in brainstem (raphe area) is affected by endogenous serotonin release in vivo and that L-DOPA treatment may cause serotonin neurons in the brainstem to corelease dopamine.

Heat shock protein 90 and tyrosine kinase regulate eNOS NO* generation but not NO* bioactivity

An increase in the association of heat shock protein 90 (HSP90) with endothelial nitric oxide (NO) synthase (eNOS) is well recognized for increasing NO (NO*) production. Despite the progress in this field, the mechanisms by which HSP90 modulates eNOS remain unclear due, in part, to the fact that geldanamycin (GA) redox cycles to generate superoxide anion (O(2)(-*) and the fact that inhibiting HSP90 with GA or radicicol (RAD) destabilizes tyrosine kinases that rely on the chaperone for maturation. In this report, we determine the extent to which these side effects alter vascular and endothelial cell function in physiologically relevant systems and in cultured endothelial cells. Vascular endothelial growth factor (VEGF)-stimulated vascular permeability, as measured by Evans blue leakage in the ears of male Swiss mice in vivo, and acetylcholine-induced vasodilation of isolated, pressurized mandibular arterioles from male C57BL6 mice ex vivo were attenuated by N(omega)-nitro-L-arginine methyl ester (L-NAME), GA, and RAD. Z-1[N-(2-aminoethyl)-N-(2-ammonoethyl)amino]diazen-1-ium-1,2-dioate (DETA-NONOate), a slow releasing NO. donor, increased vasodilation of arterioles pretreated with GA, RAD, and L-NAME equally well except at 10(-5) M, the highest concentration used, where vasodilation was greater in pressurized arterioles treated with L-NAME than in arterioles pretreated with GA or RAD alone. Both GA and RAD reduced NO* release from stimulated endothelial cell cultures and increased O(2)(-*) production in the endothelium of isolated aortas by an L-NAME-inhibitable mechanism. Pretreatment with RAD increased stimulated O(2)(-*) production from eNOS, whereas pretreatment with genistein (GE), a broad-spectrum tyrosine kinase inhibitor, did not; however, pretreatment with GE + RAD resulted in a super-induced state of uncoupled eNOS activity upon stimulation. These data suggest that the tyrosine kinases, either directly or indirectly, and HSP90-dependent signaling pathways act in concert to suppress uncoupled eNOS activity.

L-4F, an apolipoprotein A-1 mimetic, dramatically improves vasodilation in hypercholesterolemia and sickle cell disease

BACKGROUND

Hypercholesterolemia and sickle cell disease (SCD) impair endothelium-dependent vasodilation by dissimilar mechanisms. Hypercholesterolemia impairs vasodilation by a low-density lipoprotein (LDL)-dependent mechanism. SCD has been characterized as a chronic state of inflammation in which xanthine oxidase (XO) from ischemic tissues increases vascular superoxide anion (O2*-) generation. Recent reports indicate that apolipoprotein (apo) A-1 mimetics inhibit atherosclerosis in LDL receptor-null (Ldlr-/-) mice fed Western diets. Here we hypothesize that L-4F, an apoA-1 mimetic, preserves vasodilation in hypercholesterolemia and SCD by decreasing mechanisms that increase O2*- generation.

METHODS AND RESULTS

Arterioles were isolated from hypercholesterolemic Ldlr-/- mice and from SCD mice that were treated with either saline or L-4F (1 mg/kg per day). Vasodilation in response to acetylcholine was determined by videomicroscopy. Effects of L-4F on LDL-induced increases in endothelium-dependent O2*- generation were determined on arterial segments via the hydroethidine assay and on stimulated endothelial cell cultures via superoxide dismutase-inhibitable ferricytochrome c reduction. Effects of L-4F on XO bound to pulmonary arterioles and content in livers of SCD mice were determined by immunofluorescence. Hypercholesterolemia impaired vasodilation in Ldlr-/- mice, which L-4F dramatically improved. L-4F inhibited LDL-induced increases in O2*- in arterial segments and in stimulated cultures. SCD impaired vasodilation, increased XO bound to pulmonary endothelium, and decreased liver XO content. L-4F dramatically improved vasodilation, decreased XO bound to pulmonary endothelium, and increased liver XO content compared with levels in untreated SCD mice.

CONCLUSIONS

These data show that L-4F protects endothelium-dependent vasodilation in hypercholesterolemia and SCD. Our findings suggest that L-4F restores vascular endothelial function in diverse models of disease and may be applicable to treating a variety of vascular diseases.

Serotonin transporter availability correlates with alcohol intake in non-human primates

A low level of alcohol intoxication upon initial exposure and impulsive aggressiveness predispose humans to alcoholism. In non-human primates, central serotonin transporter availability and turnover rate were associated with aggressive behavior and a low response to initial alcohol exposure. We assessed the respective effects of these factors on alcohol intake in a free choice paradigm. Serotonin transporter availability in the raphe area, the origin of central serotonergic projections, was measured with single-photon emission computed tomography and the radioligand [(123)I]beta-CIT in 11 rhesus monkeys with low and high central serotonin turnover. The amount of alcohol intake in the 3-month observation period was positively correlated with serotonin transporter availability (R=0.76, P=0.006), but not with aggressiveness (R=0.19, P=0.6) or alcohol response upon first exposure (R=-0.48, P=0.2). In a linear multiple regression analysis with serotonin transporter availability, alcohol response, and aggressiveness as independent variables, 82% of the variance of alcohol intake was explained and serotonin transporter availability emerged as the only statistically significant factor (beta=7.81, P=0.006). These observations indicate that there may be a direct relationship between serotonin transporter availability and alcohol intake after controlling for aggression and alcohol response on first exposure.

Changes in high molecular weight kininogen levels during and after cardiopulmonary bypass surgery measured using a chromogenic peptide substrate assay

High molecular weight kininogen (HK) is a co-factor in the blood-contact activation system. A chromogenic peptide substrate assay for HK (HKcs) has been developed in which test plasmas are mixed with diluted HK-deficient plasma and incubated with a soluble contact system activator that activates prekallikrein and factor XII. Calcium chloride, a synthetic thrombin inhibitor and a chromogenic peptide substrate for activated factor X (FXa) are then added. The FXa generated cleaves the FXa substrate releasing p-nitroanaline, which is measured photometrically. Test plasma HK values were calculated from a standard curve generated using a pooled normal plasma. Acceptable intra-assay and inter-assay precision values were obtained and levels of HK up to 200% were measurable. The assay measured HK in plasmas deficient in factor XII, prekallikrein and factor XI, was not affected by antiphospholipid antibodies and gave an acceptable correlation (r = 0.95) when normal plasmas and mixtures of HK-deficient and normal pooled plasma, calculated to give HK levels of 25 and 50%, were compared using HKcs and a HK one-stage clotting assay. The HKcs was used to measure HK levels in seven patients undergoing cardiopulmonary bypass (CPB). HK levels fell significantly during CPB (P = 0.0014) and were significantly higher (P = 0.016) 6 days after CPB, suggesting that HK may be a positive acute-phase reacting protein.

Relationship between cortisol and serotonin metabolites and transporters in alcoholism [correction of alcolholism]

BACKGROUND

Stress hormone activation may induce clinical depression via an interference with central serotonergic neurotransmission. In alcoholics, a reduction in serotonin transporters was associated with clinical depression, and an activation of cortisol secretion is frequently found during detoxification. We assessed the interaction between stress hormone activation, serotonin transporters, monoamine metabolites in the cerebrospinal fluid (CSF), and mood states in male and female alcoholics and healthy control subjects.

METHODS

The availability of serotonin transporters was measured with [I-123]beta-CIT and SPECT in the raphe area of the brainstem in 31 alcoholics after four weeks of abstinence and in 25 age-matched healthy volunteers. Concentrations of plasma cortisol were measured on the day of the SPECT scan. Within one week after the SPECT scan, we assessed monoamine metabolites and corticotropin-releasing factor (CRF) in the CSF.

RESULTS

Clinical depression was associated with a reduction in serotonin transporter availability among male alcoholics. Among male alcoholics and healthy volunteers, CSF 5-HIAA and plasma cortisol concentrations were inversely correlated with the availability of raphe serotonin transporters and positively correlated with the severity of clinical depression. No significant correlations were observed between raphe serotonin transporters and HVA, MHPG and CRF concentrations in the CSF.

CONCLUSION

Our findings support the hypothesis of an interaction between reduced serotonin transporters, stress hormone activation and clinical depression. They confirm the hypothesis that serotonergic neurotransmission dysfunction in alcoholism is limited to male alcoholics. The observed interactions between high cortisol concentrations and reduced serotonin transporter availability warrant further studies in major depression and other neuropsychiatric diseases with implied cortisol activation and serotonergic dysfunction.

Therapeutic considerations in the treatment of obesity hypertension

Obesity, now recognized as an independent risk factor for cardiovascular disease, is closely associated with hypertension. Complex mechanisms link increasing body weight with increasing blood pressure. Treatment of the obese patient with hypertension requires consideration of physiologic changes related to obesity hypertension. Lifestyle modification, including weight reduction and increased physical activity, can directly influence blood pressure levels and improve blood pressure control in obese, hypertensive patients. Clinical trials are needed to determine the most effective antihypertensive drugs for the obese, hypertensive patient. Antiobesity drugs offer viable adjunctive pharmacotherapy for obesity hypertension, but additional long-term studies are needed to support their safety and efficacy.

Associations between weight gain and incident hypertension in a bi-ethnic cohort: the Atherosclerosis Risk in Communities Study

OBJECTIVE

To examine associations between weight gain and changes in blood pressure and the incidence of hypertension in four ethnicity-gender groups.

DESIGN

Longitudinal closed cohort studied over an average of 6 y.

SUBJECTS

Total of 9309 white and African-American men and women 45-64 y of age who participated in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS

Weight and blood pressure were measured at baseline and after an average of 3 and 6 y of follow-up. Proportional hazard models with weight gain as a time-dependent variable were used to examine the association between weight gain and changes in blood pressure and hypertension. Multivariate models were used with baseline SBP, DBP, age, BMI, height, WHR, smoking, physical activity, education, caloric intake, fat intake and study center as covariates.

RESULTS

Weight gain was associated with increases in SBP and DBP in all groups. Hazard ratios for hypertension associated with 1 kg annual weight gain were 1.36 (95% CI, 1.29, 1.45) in white women, 1.12 (95% CI, 1.03, 1.21) in African-American women, 1.35 (95% CI, 1.27, 1.43) in white men and 1.43 (95% CI, 1.27,1.61) in African-American men.

CONCLUSION

Weight gain was associated with increased blood pressure and increased incidence of hypertension. The association was weaker among African-American women compared to other ethnicity-gender groups.

Ankle-brachial index and 7-year ischemic stroke incidence: the ARIC study

BACKGROUND AND PURPOSE

Low ankle-brachial index (ABI), which is the ratio of tibial artery systolic blood pressure to brachial systolic artery pressure, is known to be a measure of lower limb peripheral artery disease as well as a marker for other cardiovascular disease events. The ability of ABI to predict incident ischemic stroke, however, is not established in population-based studies.

METHODS

ABI was measured in a cohort of 14 839 black and white men and women aged 45 to 64 years. Stroke incidence was calculated during approximately 7 years of follow-up.

RESULTS

A total of 206 incident strokes occurred. Adjusted stroke incidence rates were markedly higher for those in the lowest versus the highest categories of ABI for men, women, blacks, and whites. The proportional hazards regression model, adjusted for age, race, gender, and field center, showed an inverse linear trend between ABI and ischemic stroke incidence (P<0.0001). The lowest group (ABI <0.80) had a hazard ratio of 5.68 (95% CI 2.77 to 11.66). After adjustment for major risk factors in a multivariate model, the hazard ratio in the lowest group was elevated (1.93) but no longer statistically significant (95% CI 0.78 to 4.78). There was, however, still an indication of an overall inverse linear trend between ABI and incident stroke (P=0.03).

CONCLUSIONS

Low ABI was strongly associated with increased incidence of ischemic stroke, but the relationship was substantially reduced after adjustment for major cardiovascular risk factors.

Antihypertensive effect of alpha- and beta-adrenergic blockade in obese and lean hypertensive subjects

The purpose of this study was to determine the contribution of the adrenergic system in mediating hypertension in obese and lean patients. Thirteen obese, hypertensive patients with a body mass index (BMI) > or =28 kg/m2 (obese) and nine lean patients with a BMI < or =25 kg/m2 (lean) were recruited. After a 1-week washout period, participants underwent daytime ambulatory blood pressure monitoring (ABPM). Participants were then treated with the alpha-adrenergic antagonist doxazosin, titrating to 4 mg QHS in 1 week. In the next week, the beta-adrenergic antagonist atenolol was added at an initial dose of 25 mg/day and titrated to 50 mg/day within 1 week. One month after the addition of atenolol, all patients underwent a second ABPM session. There were no differences between the obese and lean subjects in baseline systolic (SBP), diastolic (DBP), or mean arterial pressures (MAP) measured by office recording or ABPM. However, obese subjects had higher heart rates than lean subjects (87.5+/-2.4 v 76.8+/-4.9 beats/min). After 1 month of treatment with the adrenergic blockers, obese patients had a significantly lower SBP (130.0+/-2.5 v 138.9+/-2.1 mm Hg, P = .02) and MAP (99.6+/-2.3 v 107.0+/-1.5 mm Hg, P = .02) than lean patients. Obese patients also tended to have a lower DBP than lean patients (84.3+/-2.5 v 90.9+/-1.6 mm Hg, P = .057), but there was no significant difference in heart rate after 1 month of adrenergic blockade. These results indicate that blood pressure is more sensitive to adrenergic blockade in obese than in lean hypertensive patients and suggest that increased sympathetic activity may be an important factor in the maintenance of hypertension in obesity.

Antibodies to factor XII and recurrent fetal loss in patients with the anti-phospholipid syndrome

Forty female patients with either primary anti-phospholipid syndrome (n = 26) or systemic lupus erythematosus (anti-phospholipid syndrome positive) (n = 14) were investigated for levels of factor XII, the presence of lupus anticoagulant and antibodies to cardiolipin, beta 2-glycoprotein I and factor XII. Twenty-one patients had a history of recurrent fetal loss (> 2, mean = 2.6). Lupus anticoagulant positivity showed a weak association with recurrent fetal loss (odds ratio = 1.1). While there was no association between the presence of antibodies to cardiolipin or beta 2-glycoprotein I with recurrent fetal loss, antibodies to factor XII showed a strong and statistically significant association (odds ratio = 5.4, P = 0.025).

The importance of locally derived reference ranges and standardized calculation of dilute Russell's viper venom time results in screening for lupus anticoagulant

Three commercial dilute Russell's viper venom time (DRVVT) kits were evaluated at four UK centres experienced at performing lupus anticoagulant (LA) tests. Each centre established a normal reference range for the DRVVT ratio calculated against local pooled normal plasma from 20 healthy normal subjects. Plasma from LA-positive patients and LA-negative thrombophilia patients was also tested. DRVVT ratios and the degree of correction were assessed in a variety of ways to reflect not only the UK national Guidelines, but also the manufacturers' recommendations. The reference range data showed a normal distribution in each case, but considerable variation in the mean and SD between the centres and reagents, with the mean +2SD value ranging from 1.06 to 1.19. The use of an arbitrary DRVVT ratio of < 1.1 as the cut-off value for normality, which is applied in many laboratories, is therefore inappropriate. Although no single kit had a clear overall advantage in terms of sensitivity and specificity, the way in which the screen and confirmation data were analysed had a major impact on the interpretation of the results. A data analysis method employing a mean plus two standard deviations (SDs) cut-off for normality, and judgement regarding confirmation of LA based on a percentage correction of DRVVT ratio, was the simplest and most consistent, with overall sensitivity and specificity values of 81% and 94%, respectively, for uncomplicated LA-positive and LA-negative thrombophilia samples. We conclude that the 1991 BSCH Guidelines are in need of revision, each laboratory should establish its own normal reference range for the DRVVT ratio and a common method should be used for calculating the degree of correction with confirmation reagents, so that LA results can be correctly interpreted between laboratories. Standardizing DRVVT interpretation in this way should improve the consistency of LA detection.

Adenosine preconditions against endothelin-induced constriction of coronary arterioles

Myocardial hypoperfusion is accompanied by concomitant increases in adenosine and endothelin-1 (ET-1) production, but the vasodilatory effect of adenosine prevails over that of ET-1. Therefore, we hypothesized that adenosine-induced or ischemic preconditioning reduces the vasoconstrictive effect of ET-1. Coronary arteriolar diameter in vivo was measured using fluorescence microangiography in anesthetized open-thorax dogs. ET-1 (5 ng. kg(-1). min(-1) administered intracoronary, n = 10) induced progressive constriction over 45 min [25 +/- 6% (SE)]. The constriction was blocked by preconditioning with adenosine (25 microgram. kg(-1). min(-1) administered intracoronary) for 20 min and 10 min of washout (n = 10) or attenuated by ischemic preconditioning (four 5-min periods of ischemia, 9 +/- 5% at 45 min). To investigate the receptor involved in this process, coronary arterioles (50-150 micrometer) were isolated and pressurized at 60 mmHg in vitro. The ET-1 dose-response curve (1 pM-5 nM) was rightward shifted after preconditioning with adenosine (1 microM) for 20 min and 10 min of washout (n = 11). Blockade of A(2) receptors [8-(3-chlorostyryl)caffeine, 1 microM, n = 9] but not A(1) receptors (8-cyclopentyl-1,3-dipropylxanthine, 100 nM, n = 7) prevented this shift. These results suggest that adenosine confers a vascular preconditioning effect, mediated via the A(2) receptor, against endothelin-induced constriction. This effect may offer a new protective function of adenosine in preventing excessive coronary constriction.