SAT-562 Angiotensin II Induces Aldosterone Synthesis in the Rat Heart Stressed by Angiotensin II

Aldosterone (Aldo) causes myocardial injury and fibrosis. While most Aldo is made by the adrenal zona glomerulosa; there have been controversial reports that Aldo is also synthesized in the heart; such myocardial synthesis of Aldo might contribute to myocardial injury. We induced cardiac fibrosis in rats by infusing angiotensin II (AngII) @ 500 ng/kg/min via subcutaneous pumps. After 4 weeks, circulating corticosterone increased about 400-fold from ~29 nM to ~11 μM. Aldo synthesis in isolated mitochondria (mito) was assessed by conversion of tritiated deoxycorticosterone to Aldo; AngII infusion doubled Aldo synthesis, and this augmented synthesis was inhibited in mito from rats receiving AngII + telmisartan, which inhibits the binding of AngII to the AT1 receptor. Western blotting showed P450c11AS (Aldo synthase) was also stimulated by AngII and inhibited by telmisartan in both rat heart and H9c2 myocardial cells. 2-dimentional native PAGE and mass spectrometry showed that a 290-kDa complex on the inner mitochondrial membrane (IMM) contained P450c11AS, Tom22 (a translocase associated with the outer mitochondrial membrane, OMM), and StAR (the steroidogenic acute regulatory protein). Immunocytochemistry and transmission electron microscopy monitoring of immune-gold particles confirmed that P450c11AS, Tom22, and StAR were associated with the mito, that P450c11AS and StAR were associated with the IMM and that P450c11AS and StAR, but not Tom22, were increased by AngII. Cardiac Aldo synthesis required myocardial expression of P450c11AS, but expression of P450scc, the initial steroidogenic enzyme that converts cholesterol to pregnenolone, was undetectable, indicating the heart cannot make Aldo de novo from cholesterol. The only known action of StAR is to promote the movement of cholesterol from the OMM to IMM; nevertheless, we found that intramitochondrial StAR is required for Aldo synthesis; protein crosslinking with BS3 showed that Tom22 forms a bridge between StAR and P450c11AS. This is the first activity ascribed to intramitochondrial StAR, but the manner by which StAR promotes P450c11AS activity is unclear. As P450scc was undetectable, and circulating concentrations of corticosterone approached the Km (~28 μM) for the use of corticosterone as a substrate for P450c11AS, we suggest that cardiac P450c11AS uses circulating steroids for substrate. Thus the stressed heart produces aldosterone using a previously undescribed intramitochondrial mechanism that involves P450c11AS, Tom22 and StAR

Steroidogenic acute regulatory protein/aldosterone synthase mediates angiotensin II-induced cardiac fibrosis and hypertrophy

Aldosterone produced in adrenal glands by angiotensin II (Ang II) is known to elicit myocardial fibrosis and hypertrophy. This study was designed to test the hypothesis that Ang II causes cardiac morphological changes through the steroidogenic acute regulatory protein (StAR)/aldosterone synthase (AS)-dependent aldosterone synthesis primarily initiated in the heart. Sprague-Dawley rats were randomized to following groups: Ang II infusion for a 4-week period, treatment with telmisartan, spironolactone or adrenalectomy during Ang II infusion. Sham-operated rats served as control. Relative to Sham rats, Ang II infusion significantly increased the protein levels of AT1 receptor, StAR, AS and their tissue expression in the adrenal glands and heart. In coincidence with reduced aldosterone level in the heart, telmisartan, an AT1 receptor blocker, significantly down-regulated the protein level and expression of StAR and AS. Ang II induced changes in the expression of AT1/StAR/AS were not altered by an aldosterone receptor antagonist spironolactone. Furthermore, Ang II augmented migration of macrophages, protein level of TGFβ1, phosphorylation of Smad2/3 and proliferation of myofibroblasts, accompanied by enhanced perivascular/interstitial collagen deposition and cardiomyocyte hypertrophy, which all were significantly abrogated by telmisartan or spironolactone. However, adrenalectomy did not fully suppress Ang II-induced cell migration/proliferation and fibrosis/hypertrophy, indicating a role of aldosterone synthesized within the heart in pathogenesis of Ang II induced injury. These results indicate that myocardial fibrosis and hypertrophy stimulated by Ang II is associated with tissue-specific activation of aldosterone synthesis, primarily mediated by AT1/StAR/AS signaling pathways.

Liraglutide attenuates cardiac remodeling and improves heart function after abdominal aortic constriction through blocking angiotensin II type 1 receptor in rats

Objective

Angiotensin II (Ang II) is known to contribute to the pathogenesis of heart failure by eliciting cardiac remodeling and dysfunction. The glucagon-like peptide-1 (GLP-1) has been shown to exert cardioprotective effects in animals and patients. This study investigates whether GLP-1 receptor agonist liraglutide inhibits abdominal aortic constriction (AAC)-induced cardiac fibrosis and dysfunction through blocking Ang II type 1 receptor (AT1R) signaling.

Methods

Sprague-Dawley rats were subjected to sham operation and abdominal aortic banding procedure for 16 weeks. In treated rats, liraglutide (0.3 mg/kg) was subcutaneously injected twice daily or telmisartan (10 mg/kg/day), the AT1R blocker, was administered by gastric gavage.

Results

Relative to the animals with AAC, liraglutide reduced protein level of the AT1R and upregulated the AT2R, as evidenced by reduced ratio of AT1R/AT2R (0.59±0.04 vs. 0.91±0.06, p<0.05). Furthermore, the expression of angiotensin converting enzyme 2 was upregulated, tissue levels of malondialdehyde and B-type natriuretic peptide were reduced, and superoxide dismutase activity was increased. Along with a reduction in HW/BW ratio, cardiomyocyte hypertrophy was inhibited. In coincidence with these changes, liraglutide significantly decreased the populations of macrophages and myofibroblasts in the myocardium, which were accompanied by reduced protein levels of transforming growth factor beta1, Smad2/3/4, and upregulated smad7. The synthesis of collagen I and III was inhibited and collagen-rich fibrosis was attenuated. Consistent with these findings, cardiac systolic function was preserved, as shown by increased left ventricular systolic pressure (110±5 vs. 99±2 mmHg, p<0.05), ejection fraction (83%±2% vs. 69%±4%, p<0.05) and fraction shortening (49%±2% vs. 35%±3%, p<0.05). Treatment with telmisartan provided a comparable level of protection as compared with liraglutide in all the parameters measured.

Conclusion

Taken together, liraglutide ameliorates cardiac fibrosis and dysfunction, potentially via suppressing the AT1R-mediated events. These data indicate that liraglutide might be selected as an add-on drug to prevent the progression of heart failure.

Recruitment of macrophages from the spleen contributes to myocardial fibrosis and hypertension induced by angiotensin II

INTRODUCTION

The purpose of this study was to determine whether macrophages migrated from the spleen are associated with angiotensin II-induced cardiac fibrosis and hypertension.

METHODS

Sprague-Dawley rats were subjected to angiotensin II infusion in vehicle (500 ng/kg/min) for up to four weeks. In splenectomy, the spleen was removed before angiotensin II infusion. In the angiotensin II AT1 receptor blockade, telmisartan was administered by gastric gavage (10 mg/kg/day) during angiotensin II infusion. The heart and aorta were isolated for Western blot analysis and immunohistochemistry.

RESULTS

Angiotensin II infusion caused a significant reduction in the number of monocytes in the spleen through the AT1 receptor-activated monocyte chemoattractant protein-1. Comparison of angiotensin II infusion, splenectomy and telmisartan comparatively reduced the recruitment of macrophages into the heart. Associated with this change, transforming growth factor β1 expression and myofibroblast proliferation were inhibited, and Smad2/3 and collagen I/III were downregulated. Furthermore, interstitial/perivascular fibrosis was attenuated. These modifications occurred in coincidence with reduced blood pressure. At week 4, invasion of macrophages and myofibroblasts in the thoracic aorta was attenuated and expression of endothelial nitric oxide synthase was upregulated, along with a reduction in aortic fibrosis.

CONCLUSIONS

These results suggest that macrophages when recruited into the heart and aorta from the spleen potentially contribute to angiotensin II-induced cardiac fibrosis and hypertension.

Postconditioning attenuates coronary perivascular and interstitial fibrosis through modulating angiotensin II receptors and angiotensin-converting enzyme 2 after myocardial infarction

BACKGROUND

Postconditioning (Postcon) is known to reduce infarct size. This study tested the hypothesis that Postcon attenuates the perivascular and interstitial fibrosis after myocardial infarction through modulating angiotensin II-activated fibrotic cascade.

MATERIALS AND METHODS

Male Sprague-Dawley rats were subjected to 45-min coronary occlusion followed by 1 and 6 wk of reperfusion. Postcon was applied at the onset of reperfusion with four cycles of 10/10-s reperfusion-ischemia at the onset of reperfusion. Preconditioning (Precon) with two cycles of 5/5-min ischemia-reperfusion was applied before coronary occlusion.

RESULTS

Postcon reduced angiotensin-converting enzyme protein and expression in the perivascular area and intermyocardium, coincident with the less-expressed angiotensin II receptor, type 1, enhanced angiotensin II receptor, type 2, and angiotensin converting enzyme 2. Postcon lowered the monocyte chemoattractant protein-1 and inhibited the populations of interstitial macrophages (60 ± 12 versus 84 ± 9.5 number per high-powered field [HPF] in control, P < 0.05). Along with these modulations, Postcon also downregulated transforming growth factor β1 protein and inhibited proliferation of α-smooth muscle actin expressing myofibroblasts (41 ± 11 versus 79 ± 8.2 number per HPF in control, P < 0.05), consistent with downregulated phospho-Smad2 and phospho-Smad3. Furthermore, the synthesis of collagen I and III was attenuated, and the perivascular-interstitial fibrosis was inhibited by Postcon as demonstrated by reduced perivascular fibrosis ratio (0.6 ± 0.6 versus 1.6 ± 0.5 per HPF in control, P < 0.05) and smaller collagen-rich area (16 ± 4.7 versus 34 ± 9.2% per HPF in control, P < 0.05). Precon conferred a comparable level of protection as Postcon did in all parameters measured, suggesting protection trigged by this endogenous stimulation can be achieved when it was applied either before ischemia or after reperfusion.

CONCLUSIONS

These results suggest that Postcon could be selected as an adjunctive intervention with other existing therapeutic drugs to treat the fibrosis-derived heart failure patients after myocardial infarction.

Attenuation of myocardial fibrosis with curcumin is mediated by modulating expression of angiotensin II AT1/AT2 receptors and ACE2 in rats

Curcumin is known to improve cardiac function by balancing degradation and synthesis of collagens after myocardial infarction. This study tested the hypothesis that inhibition of myocardial fibrosis by curcumin is associated with modulating expression of angiotensin II (Ang II) receptors and angiotensin-converting enzyme 2 (ACE2). Male Sprague Dawley rats were subjected to Ang II infusion (500 ng/kg/min) using osmotic minipumps for 2 and 4 weeks, respectively, and curcumin (150 mg/kg/day) was fed by gastric gavage during Ang II infusion. Compared to the animals with Ang II infusion, curcumin significantly decreased the mean arterial blood pressure during the course of the observation. The protein level of the Ang II type 1 (AT1) receptor was reduced, and the Ang II type 2 (AT2) receptor was up-regulated, evidenced by an increased ratio of the AT2 receptor over the AT1 receptor in the curcumin group (1.2±0.02%) vs in the Ang II group (0.7±0.03%, P<0.05). These changes were coincident with less locally expressed AT1 receptor and enhanced AT2 receptor in the intracardiac vessels and intermyocardium. Along with these modulations, curcumin significantly decreased the populations of macrophages and alpha smooth muscle actin-expressing myofibroblasts, which were accompanied by reduced expression of transforming growth factor beta 1 and phosphorylated-Smad2/3. Collagen I synthesis was inhibited, and tissue fibrosis was attenuated, as demonstrated by less extensive collagen-rich fibrosis. Furthermore, curcumin increased protein level of ACE2 and enhanced its expression in the intermyocardium relative to the Ang II group. These results suggest that curcumin could be considered as an add-on therapeutic agent in the treatment of fibrosis-derived heart failure patient who is intolerant of ACE inhibitor therapy.

Curcumin promotes cardiac repair and ameliorates cardiac dysfunction following myocardial infarction

BACKGROUND AND PURPOSE

Curcumin, the natural yellow pigment extracted from the rhizomes of the plant curcuma longa, has been demonstrated to exhibit a variety of potent beneficial effects, acting as an antioxidant, anti-inflammatory and anti-fibrotic. In this study we tested the hypothesis that curcumin attenuates maladaptive cardiac repair and improves cardiac function after ischaemia and reperfusion by reducing degradation of extracellular matrix (ECM) and inhibiting synthesis of collagens via TGFβ/Smad-mediated signalling pathway.

EXPERIMENTAL APPROACH

Sprague-Dawley rats were subjected to 45 min of ischaemia followed by 7, 21 and 42 days of reperfusion respectively. Curcumin was fed orally at a dose of 150 mg·kg(-1) ·day(-1) only during reperfusion.

KEY RESULTS

Curcumin reduced the level of malondialdehyde, inhibited activity of MMPs, preserved ECM from degradation and attenuated collagen deposition, as it reduced the extent of collagen-rich scar and increased mass of viable myocardium. In addition to reducing collagen synthesis and fibrosis in the ischaemic/reperfused myocardium, curcumin significantly down-regulated the expression of TGFβ1 and phospho-Smad2/3, and up-regulated Smad7 and also increased the population of α-smooth muscle actin expressing myofibroblasts within the infarcted myocardium relative to the control. Echocardiography showed it significantly improved left ventricular end-diastolic volume, stroke volume and ejection fraction. The wall thickness of the infarcted middle anterior septum in the curcumin group was also greater than that in the control group.

CONCLUSION AND IMPLICATIONS

Dietary curcumin is effective at inhibiting maladaptive cardiac repair and preserving cardiac function after ischaemia and reperfusion. Curcumin has potential as a treatment for patients who have had a heart attack.

Improvement in cardiac function with small intestine extracellular matrix is associated with recruitment of C-kit cells, myofibroblasts, and macrophages after myocardial infarction

OBJECTIVES

This study tested the hypothesis that modulation of angiogenesis and cardiac function by injecting small intestine extracellular matrix emulsion (EMU) into myocardium is associated with recruitment of c-kit cells, myofibroblasts, and macrophages after myocardial infarction.

BACKGROUND

Degradation of native extracellular matrix has been associated with adverse cardiac remodeling after infarction.

METHODS

Sixty-four rats were subjected to 45 min ischemia followed by 3, 7, 21, and 42 days of reperfusion, respectively. Saline or EMU (30 to 50 microl) was injected into the area at risk myocardium after reperfusion. Histological examination was performed by immunohistochemical staining, and cardiac function was analyzed using echocardiography.

RESULTS

The population of c-kit-positive cells in infarcted myocardium with the EMU injection increased significantly relative to the saline control at 7 days of reperfusion. Along with this change, alpha-smooth muscle actin expressing myofibroblasts and macrophages accumulated to a significant extent compared with the saline control. Increased vascular endothelial growth factor protein level and strong immunoreactivity of vascular endothelial growth factor expression were observed. Angiogenesis in the EMU area was significantly enhanced relative to the saline control, evidenced by increased density of alpha-smooth muscle actin positive vessels. Furthermore, echocardiography showed significant improvements in fractional shortening, ejection fraction, and stroke volume in the EMU group. The wall thickness of the infarcted middle anterior septum in the EMU group was significantly increased relative to the saline control.

CONCLUSIONS

We show for the first time that injection of EMU into the infarcted myocardium increases neovascularization and preserves cardiac function, potentially mediated by enhanced recruitment of c-kit-positive cells, myofibroblasts, and macrophages.

Factor Xa induces tissue factor expression in endothelial cells by P44/42 MAPK and NF-κB-dependent pathways

BACKGROUND

Tissue factor (TF) is an initiator of coagulation. The serine protease factor Xa (FXa) is the convergence point of the extrinsic and intrinsic components of the coagulation cascade. In addition to its hemostatic function, FXa elicits inflammatory responses in endothelial cells that may be important in surgical procedures in which inflammation is triggered. This study tested the hypothesis that FXa can up-regulate TF on vascular endothelial cells by a mitogen-activated protein kinase (MAPK)- and NF-κB-dependent pathway.

METHODS AND RESULTS

Incubation of cultured human umbilical vein endothelial cells (HUVECs) with FXa increased TF protein expression and activity in a dose-dependent manner. Pre-incubation of HUVECs with the serine protease inhibitor antithrombin, which targets not only thrombin but also FXa and FIXa, inhibited FXa-induced TF expression, but the selective thrombin inhibitor hirudin did not inhibit FXa-induced TF expression, ruling out a thrombin-mediated pathway. After 10 min incubation with HUVECs, FXa rapidly induced P44/42 MAPK activation (immunoblotting of phosphorylated P44/42 MAPK) with a peak at 30 min. The MEK 1/2 inhibitor PD98059 partially reduced FXa-induced TF expression and activity (3.82 ± 0.11 vs 6.54 ± 0.08 fmol/min/cm(2), P < 0.05). NF-κB was activated by FXa, confirmed by cytoplasmic IkBα degradation and increased NF-κB P65 nuclear translocation. Interruption of the NF-κB pathway by the IkBα phosphorylation inhibitor Bay 11-7802 abrogated FXa-induced TF protein expression and activity (1.93 ± 0.02 versus 6.54 ± 0.08 fmol/min/cm(2), P < 0.05). However, inhibition of PI3 kinase by LY 294002 did not attenuate FXa-induced TF protein expression and activity.

CONCLUSIONS

(1) FXa up-regulates TF protein expression and activity in HUVECs, (2) FXa-induced up-regulation of TF is independent of the thrombin-PAR1 pathway, and (3) the MAPK and NF-κB pathways, but not PI3 kinase pathway, are involved in FXa-induced TF expression on human umbilical endothelial cells. FXa may be a feed-forward alternative mechanism of activating TF expression and activity, thereby increasing a procoagulant state or inflammation. This mechanism may be important in the pro-inflammatory state initiated by cardiac surgical procedures.

Attenuation of renal ischemia-reperfusion injury by postconditioning involves adenosine receptor and protein kinase C activation

SUMMARY

Significant organ injury occurs after transplantation and reflow (i.e., reperfusion injury). Postconditioning (PoC), consisting of alternating periods of reperfusion and re-occlusion at onset of reperfusion, attenuates reperfusion injury in organs including heart and brain. We tested whether PoC attenuates renal ischemia-reperfusion (I/R) injury in the kidney by activating adenosine receptors (AR) and protein kinase C (PKC). The single kidney rat I/R model was used. Groups: (1) sham: time-matched surgical protocol only. In all others, the left renal artery (RA) was occluded for 45 min and reperfused for 24 h. (2) CONTROL: I/R with no intervention at R. All antagonists were administered 5 min before reperfusion. (3) PoC: I/R + four cycles of 45 s of R and 45 s of re-occlusion before full R. (4) PoC + ARi: PoC plus the AR antagonist 8-rho-(sulfophenyl) theophylline (8-SPT). (5) PoC + PKCi: PoC plus the PKC antagonist chelerythrine (Che). In shams, plasma blood urea nitrogen (BUN mg/dl) at 24 h averaged 23.2 +/- 5.3 and creatinine (Cr mg/dl) averaged 1.28 +/- 0.2. PoC reduced BUN (87.2 +/- 10 in CONTROL vs. 38.8 +/- 9, P = 0.001) and Cr (4.2 +/- 0.6 in CONTROL vs. 1.5 +/- 0.2, P < 0.001). 8-SPT and Che reversed renal protection indices after PoC. I/R increased apoptosis, which was reduced by PoC, which was reversed by 8-SPT and Che. Postconditioning attenuates renal I/R injury by adenosine receptor activation and PKC signaling.

Intravenous infusion of mesenchymal stem cells enhances regional perfusion and improves ventricular function in a porcine model of myocardial infarction

Transplantation of stem cells may improve regional perfusion and post-infarct ventricular function, but the optimal dose and efficacy of cell delivery via the intravenous route has not been determined. This study tested the hypothesis that intravenous infusion of bone marrow-derived mesenchymal stem cells (MSCs) enhances regional perfusion and improves ventricular function after myocardial infarction. In a closed-chest pig model, the LAD coronary artery was occluded for 75 min by angioplasty balloon inflation followed by 12 weeks of reperfusion. After 15 min of reperfusion, pigs randomly received 1 of 4 treatments: (1) Vehicle (Control, n = 10); (2) 1 x 10(6) MSCs/kg (1 mill, n = 7); (3) 3 x 10(6) MSCs/kg (3 mill, n = 8) and (4) 10 x 10(6) MSCs/kg (10 mill, n = 8). Angiogenesis was demonstrated by immunohistochemical staining, myocardial blood flow (steady state and vasodilator reserve) was measured using 15 microm neutron-activated microspheres, and cardiac function was determined by contrast left ventriculography (ejection fraction) and pressure-volume relationships. After 12 week of reperfusion, von Willebrand Factor-positive vessels and tissue vascular endothelial growth factor (VEGF) expression in the scar zone was significantly greater in all MSCs-treated animals relative to Control. Steady state myocardial blood flow in the scar tissue was comparable among groups. However, adenosine recruited vasodilator reserve in the scar zone induced by intracoronary adenosine was significantly higher in the MSC-treated animals compared to Control. Furthermore, preload-recruitable stroke work and systolic performance were significantly greater compared to Control. In conclusion, these data demonstrate that intravenous delivery of MSCs during early reperfusion augments vasculogenesis, enhances regional perfusion, and improves post-infarct ventricular function. The results suggest that intravenous infusion of MSCs is an effective modality for the treatment of ischemia/reperfusion induced myocardial injury.

Persistent beneficial effect of postconditioning against infarct size: role of mitochondrial K(ATP) channels during reperfusion

This study tested the hypothesis that inhibition of myocardial injury and modulation of mitochondrial dysfunction by postconditioning (Postcon) after 24 h of reperfusion is associated with activation of K(ATP) channels. Thirty dogs undergoing 60 min of ischemia and 24 h of reperfusion (R) were randomly divided into four groups:

CONTROL

no intervention at R; Postcon: three cycles of 30 s R alternating with 30 s re-occlusion were applied at R; 5-hydroxydecanoate (5-HD): the mitochondrial K(ATP) channel blocker was infused 5 min before Postcon; HMR1098: the sarcolemmal K(ATP) channel blocker was administered 5 min before Postcon. After 24 h of R, infarct size was smaller in Postcon relative to CONTROL (27 +/- 4%* Vs. 39 +/- 2% of area at risk), consistent with a reduction in CK activity (66 +/- 7* Vs. 105 +/- 7 IU/g). The infarct-sparing effect of Postcon was blocked by 5-HD (48 +/- 5%(dagger)), but was not altered by HMR1098 (29 +/- 3%*), consistent with the change in CK activity (102 +/- 8(dagger) in 5-HD and 71 +/- 6* IU/g in HMR1098). In H9c2 cells exposed to 8 h hypoxia and 3 h of reoxygenation, Postcon up-regulated expression of mito-K(ATP) channel Kir6.1 protein, maintained mitochondrial membrane potential and inhibited mitochondrial permeability transition pore (mPTP) opening evidenced by preserved fluorescent TMRE and calcein staining. The protective effects were blocked by 5-HD, but not by HMR1098. These data suggest that in a clinically relevant model of ischemia-reperfusion (1) Postcon reduces infarct size and decreases CK activity after prolonged reperfusion; (2) protection by Postcon is achieved by opening mitochondrial K(ATP) channels and inhibiting mPTP opening. *P < 0.05 Vs. CONTROL; P < 0.05 Vs. Postcon.

Postconditioning attenuates cardiomyocyte apoptosis via inhibition of JNK and p38 mitogen-activated protein kinase signaling pathways

A sequence of intermittent interruptions of oxygen supply (i.e., postconditioning, Postcon) at reoxygenation reduces oxidant-induced cardiomyocyte loss. This study tested the hypothesis that prevention of cardiomyocyte apoptosis by Postcon is mediated by mitogen-activated protein kinases pathways. Primary cultured neonatal rat cardiomyocytes were exposed to 3 h hypoxia followed by 6 h of reoxygenation. Cardiomyocytes were postconditioned by three cycles each of 5 min reoxygenation and 5 min hypoxia after prolonged hypoxia. Relative to hypoxia alone, reoxygenation stimulated expression of JNKs and p38 kinases, corresponding to increased activity of JNKs (phospho-c-Jun) and p38 (phospho-ATF2). The level of TNFalpha in cell lysates, activity of cytosolic caspases-8, -3, expression of Bax and the number of apoptotic cardiomyocytes were increased while expression of Bcl-2 was decreased with reoxygenation. Consistent with an attenuation in generation of superoxide anions detected by lucigenin-enhanced chemiluminescence at early period of reoxygenation, treatment of cardiomyocytes with Postcon further reduced expression and activity of JNKs and p38 kinases, level of TNFalpha, the frequency of apoptotic cells and expression of Bax. However, the inhibitory effects of Postcon on these changes were lost when its application was delayed by 5 min after the start of reoxygenation. Addition of a JNK/p38 stimulator, anisomycin into cardiomyocytes at the beginning of reoxygenation eliminated protection by Postcon. These data suggest that 1) hypoxia/reoxygenation elicits cardiomyocyte apoptosis in conjunction with expression and activation of JNK and p38 kinases, release of TNFalpha, activation of caspases, and an increase in imbalance of pro-/anti-apoptotic proteins; 2) Postcon attenuates cardiomyocyte apoptosis, potentially mediated by inhibiting JNKs/p-38 signaling pathways and reducing TNFalpha release and caspase expression.

Cobalt Chloride Pretreatment Attenuates Myocardial Apoptosis After Hypothermic Circulatory Arrest

BACKGROUND

Deep hypothermic circulatory arrest (DHCA) causes myocyte injury as a consequence of ischemia and reperfusion. Previous studies have shown that hypoxia or hypoxia-mimetic agents (cobalt chloride [CoCl2] or deferoxamine [DFX]) limit myocyte necrosis by upregulating the transcription factor hypoxia-inducible factor. However, it remains unknown whether these agents attenuate myocardial apoptosis after DHCA. This study tested the hypotheses (1) that hypoxia, DFX, or CoCl2 preconditioning attenuates myocardial apoptosis during DHCA; and (2) that the protective mechanism involves the altered expression of apoptosis regulatory proteins pAkt (antiapoptotic), Bcl-2 (antiapoptotic), and Bax (proapoptotic).

METHODS

Anesthetized neonatal piglets were randomly assigned to four groups (n = 6 in a group): control (NaCl injection); hypoxia (pO2 of 30 to 40 mm Hg for 3 hours); DFX injection; or CoCl2 injection. Twenty-four hours later, the animals underwent cardiopulmonary bypass (CPB) and 110 minutes of DHCA. One week after CPB, percentage of apoptotic myocytes (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling [TUNEL] assay) and expression of the pAKT, Bcl-2, and Bax were assessed by Western blot.

RESULTS

Although preconditioning with hypoxia and DFX failed to show a protective benefit, CoCl2 pretreatment significantly attenuated myocardial apoptosis (9.3% +/- 4.1%) versus controls (33.8% +/- 9.7%, p = 0.042). That was associated with increased myocardial pAkt expression (0.19 +/- 0.006 in CoCl2 versus 0.12 +/- 0.008 in control, p < 0.001). The expression of Bcl-2 was also significantly higher in the CoCl2 group (0.15 +/- 0.02) versus control (0.11 +/- 0.01, p = 0.007), whereas Bax expression was lower (0.34 +/- 0.04 versus 0.54 +/- 0.03 for control, p < 0.001).

CONCLUSIONS

Preconditioning with CoCl2 before prolonged DHCA in neonatal piglets attenuates myocardial apoptosis by mechanisms involving phosphorylation of Akt, upregulation of the antiapoptotic protein Bcl-2, and decreased expression of the proapoptotic protein Bax.

Neutrophil depletion reduces myocardial apoptosis and attenuates NFkappaB activation/TNFalpha release after ischemia and reperfusion

BACKGROUND

This study tested the hypothesis that depletion of neutrophils (PMNs) reduces myocardial apoptosis via reducing oxidant generation and inhibiting NFkappaB-mediated signaling pathways after ischemia/reperfusion.

METHODS

Anesthetized rats were randomly divided into one of four groups:

CONTROL

30 min ischemia and 3 h of reperfusion; PMN depletion: anti-PMN serum was injected 6 h before ischemia; N-acetylcysteine (NAC): NAC was given twice before ischemia and at reperfusion. Sham: the ligature was placed without coronary occlusion. Apoptosis was detected by TUNEL staining and DNA fragmentation. PMN accumulation was studied by immunohistochemical staining. Levels of TNF-alpha, IL-6, and caspase-3 were detected by Elisa kits. Expression in NFkappaB, Bcl-2, and Bax was assessed by Western blotting analysis.

RESULTS

Relative to CONTROL, depletion of PMNs or NAC treatment reduced levels of plasma TNFalpha (567 +/- 130* and 231 +/- 72* versus 1994 +/- 447 pg/ml) and IL-6 (791 +/- 473* and 666 +/- 300* versus 3724 +/- 1233, pg/ml), accompanying a reduction in PMN accumulation (12 +/- 1* and 13 +/- 0.6* versus 20 +/- 1 mm2 myocardium) in ischemic myocardium. Both groups showed a reduction in expression of nuclear NFkappaB relative to CONTROL (62 +/- 9* and 67 +/- 8* versus 124 +/- 16 arb.u), consistent with reduced NFkappaB binding activity. The number of apoptotic cells (%) in area at risk myocardium was comparably reduced in anti-PMN and NAC groups relative to CONTROL (12 +/- 1* and 14 +/- 0.9* versus 20 +/- 1), consistent with reduced appearance of DNA ladders. Furthermore, activated caspase-3 was significantly reduced and Bcl-2 was increased relative to CONTROL. No difference in all parameters measured was detected during the course of experiment in the Sham group.

CONCLUSION

These data suggest that the oxidants generated from activated PMNs after ischemia/reperfusion trigger myocardial apoptosis, which is further supported by an anti-oxidant therapy with NAC, potentially mediated by enhanced NFkappaB-TNFalpha signaling pathway, activated caspase-3 and down-regulated Bcl-2. *P < 0.05 versus CONTROL.

Myocardial protection with postconditioning is not enhanced by ischemic preconditioning

BACKGROUND

Ischemic preconditioning (IPC) has been used in off-pump coronary artery bypass surgery (OPCAB) to reduce potential injury secondary to ligation of the target vessel. Previous studies have shown that a brief period of repetitive coronary occlusion applied at the onset of reperfusion, postconditioning (postcon), attenuates myocardial injury. This study tested the hypothesis that coincident application of IPC and postcon would provide more cardioprotection than either intervention alone by inhibiting oxidant-mediated injury after ischemia and reperfusion.

METHODS

Four groups of open-chest canines endured 60 minutes coronary occlusion followed by 3 hours reperfusion: control (n = 10), no intervention; IPC (n = 9), 5 minutes left anterior descending coronary artery occlusion preceded 10 minutes of reperfusion before prolonged occlusion; postcon (n = 10), 3 cycles of 30 seconds reperfusion-30 seconds reocclusion were imposed immediately upon reperfusion; IPC+postcon (n = 8), IPC and postcon algorithms were combined.

RESULTS

Collateral blood flow during ischemia was similar in all groups. Compared to control (24% +/- 2%), infarct size was comparably reduced in IPC (13% +/- 2%* [* denotes p less than 0.05 compared with control]), and postcon (10% +/- 1%*), consistent with a reduction in plasma creative kinase activity in these groups; infarct size was not further reduced by IPC+postcon (12% +/- 3%*). Tissue water content in ischemic myocardium was comparably reduced in IPC, postcon, and IPC+postcon compared to control. Superoxide anion generation detected by dihydroethidium staining in area at risk myocardium was comparably reduced in all intervention groups relative to control. Plasma malondialdehyde (microM), a lipid peroxidation byproduct of oxidant injury, was less at 1 hour of reperfusion in IPC (2.2 +/- 0.2*), postcon (2.1 +/- 0.2*), and IPC+postcon (2.5 +/- 0.2*) relative to control (3.3 +/- 0.2). Ventricular fibrillation occurred less often in all intervention groups.

CONCLUSIONS

No additive cardioprotective effects by IPC and postcon were observed in a canine model of regional ischemia and reperfusion. The potent attenuation of myocardial injury by postcon may suggest a clinically applicable strategy during some surgical revascularization procedures (ie, OPCAB).

Involvement of Na+/H+ exchanger in hypoxia/re-oxygenation-induced neonatal rat cardiomyocyte apoptosis

Although increased Na(+)/H(+) exchanger type-1 (NHE-1) activity has been implicated in the pathogenesis of myocardial infarction, the role of NHE-1 in induction of apoptosis, and the potential mechanisms involved have not been fully characterized. This study tested the hypothesis that NHE-1 activity is involved in hypoxia (H)/re-oxygenation (Re)-induced cardiomyocyte apoptosis by increasing mitochondrial Ca(2+) ([Ca(2+)]m). Primary cultured neonatal rat cardiomyocytes were subjected to 4.5 h of H followed by 12 h of Re. Relative to H alone, the level of X-rhod-1 acetoxymethyl (AM)-labeled [Ca(2+)]m was increased, and the frequency of cell death (propidium iodide (PI) staining) and apoptotic cells (terminal deoxynucleotidyl transferase (TdT)-mediated-UTP nick end labeling [TUNEL]), confirmed by Annexin-V, were augmented at the end of Re, along with appearance of cytosolic cytochrome c, activation of caspase-3, and increased ratio of Bax and Bcl-2. Addition of cariporide (20 micromol/l), a well-known NHE-1 inhibitor, to cultured cells before H significantly reduced [Ca(2+)]m, the number of PI and TUNEL positive cells relative to the levels at end of Re, but did not completely eliminate these changes compared to Sham control. There was a strong trend for attenuation in increased levels of [Ca(2+)]m, and the number of PI and TUNEL positive cells when same dose of cariporide was added only at Re, but the difference in these variables did not reach significance. In contrast, the levels of [Ca(2+)]m and the number of PI and TUNEL positive cells were significantly reduced to a level comparable to Sham control when cariporide (20 micromol/l) was administered before H and during Re, respectively, associated with a reduction in cytosolic cytochrome c, caspase-3 activity and ratio of Bax and Bcl-2. In conclusion, these data suggest that NHE-1 is involved in induction of cardiomyocyte apoptosis during both H and Re through a [Ca(2+)]m-dependent manner, thereby resulting in activation of cytochrome c-caspase-3 signaling pathways.

Hypoxic postconditioning reduces cardiomyocyte loss by inhibiting ROS generation and intracellular Ca2+ overload

We have shown that intermittent interruption of immediate reflow at reperfusion (i.e., postconditioning) reduces infarct size in in vivo models after ischemia. Cardioprotection of postconditioning has been associated with attenuation of neutrophil-related events. However, it is unknown whether postconditioning before reoxygenation after hypoxia in cultured cardiomyocytes in the absence of neutrophils confers protection. This study tested the hypothesis that prevention of cardiomyocyte damage by hypoxic postconditioning (Postcon) is associated with a reduction in the generation of reactive oxygen species (ROS) and intracellular Ca(2+) overload. Primary cultured neonatal rat cardiomyocytes were exposed to 3 h of hypoxia followed by 6 h of reoxygenation. Cardiomyocytes were postconditioned after the 3-h index hypoxia by three cycles of 5 min of reoxygenation and 5 min of rehypoxia applied before 6 h of reoxygenation. Relative to sham control and hypoxia alone, the generation of ROS (increased lucigenin-enhanced chemiluminescence, SOD-inhibitable cytochrome c reduction, and generation of hydrogen peroxide) was significantly augmented after immediate reoxygenation as was the production of malondialdehyde, a product of lipid peroxidation. Concomitant with these changes, intracellular and mitochondrial Ca(2+) concentrations, which were detected by fluorescent fluo-4 AM and X-rhod-1 AM staining, respectively, were elevated. Cell viability assessed by propidium iodide staining was decreased consistent with increased levels of lactate dehydrogenase after reoxygenation. Postcon treatment at the onset of reoxygenation reduced ROS generation and malondialdehyde concentration in media and attenuated cardiomyocyte death assessed by propidium iodide and lactate dehydrogenase. Postcon treatment was associated with a decrease in intracellular and mitochondrial Ca(2+) concentrations. These data suggest that Postcon treatment reduces reoxygenation-induced injury in cardiomyocytes and is potentially mediated by attenuation of ROS generation, lipid peroxidation, and intracellular and mitochondrial Ca(2+) overload.

Postconditioning attenuates myocardial ischemia-reperfusion injury by inhibiting events in the early minutes of reperfusion

OBJECTIVE

We previously showed that brief intermittent ischemia applied during the onset of reperfusion (i.e., postconditioning) is cardioprotective in a canine model of ischemia-reperfusion. This study tested the hypothesis that the early minutes of reperfusion (R) during which postconditioning (Post-con) is applied are critical to its cardioprotection.

METHODS

In anesthetized open-chest rats, the left coronary artery (LCA) was occluded for 30 min and reperfused for 3 h. All rats were randomly divided into six groups: Control (n=8): no intervention at R; Ischemic preconditioning (IPC) (n=8): the LCA was occluded for 5 min followed by 10 min of R before the index occlusion; Post-con 1 (n=8): after LCA occlusion, three cycles of 10 s R followed by 10 s LCA re-occlusion were applied during the first minute of R; Post-con 2 (n=8): Six cycles of 10 s R and 10 s re-occlusion were applied during the first 2 min of R; Delayed Post-con (n=8): the ligature was loosened for full reflow for the first minute of R, after which the three-cycle Post-con algorithm was applied; Sham (n=6): the surgical procedure was identical to other groups, but the LCA ligature was not ligated.

RESULTS

Infarct size (TTC staining) was 23% smaller in Post-con 1 (40+/-2%*) than in Control (52+/-3%), confirmed by plasma creatine kinase activity (18+/-2* vs. 46+/-6 IU/g protein). There was no further reduction in infarct size with 6 cycles of Post-con (40+/-2.9%, p>0.05 vs. Post-con 1). Meanwhile, infarct size reduction was significantly greater in the IPC group (17+/-3%) than in Post-con1 (p<0.01). The plasma lipid peroxidation product malondialdehyde (MDA, microM/ml) was less after R in IPC and Post-con 1 (0.8+/-0.07* and 0.8+/-0.06*) vs. Control (1.21+/-0.08), consistent with a visual decrease in superoxide anion generation (dihydroethidium staining) in the AAR myocardium after 3 h of reperfusion. Neutrophil accumulation (myeloperoxidase activity, MPO, U/100 g tissue) in the AAR was less in IPC (1.4+/-0.3*) and Post-con 1 (2.5+/-0.3*) vs. Control (5.5+/-0.6). The reductions in infarct size, creatine kinase, MDA and DHE staining were lost with delayed Post-con, while MPO activity remained lower than in Control (3.2+/-0.4*).

CONCLUSIONS

(1) Post-con at onset of R reduces myocardial injury; (2) cardioprotection may be mediated, in part, by inhibiting oxidant generation and oxidant mediated injury; (3) the first minute of R in the rat model is critical to cardioprotection by Post-con; and (4) cardioprotection by Post-con may be independent of neutrophil accumulation in AAR. *p<0.05 Post-con vs. Control.

Reduction of infarct size and preservation of endothelial function by multidose intravenous adenosine during extended reperfusion

It has been proposed that infarct extension is developed from the early to the late phase of reperfusion (R). This study compares the protective effect of single or multidose administration of adenosine (Ado) on infarct size during early and late phases of R by attenuating neutrophil (PMN) recruitment. Forty-one dogs underwent 60-min left anterior descending artery (LAD) ischemia followed by 6, 24, and 48 h of R, respectively. Infarct size (%) increased over 6 to 24 h (27 +/- 2 to 38 +/- 4; P < 0.05 24 h versus 6 h group), with a corresponding increase in creatine kinase activity. Transmural myocardial blood flow (mL/min/g) decreased from 6 to 24 h (0.47 +/- 0.02 to 0.29 +/- 0.02; P < 0.05 24 h versus 6 h group). PMN localization (mm(2) myocardium) in the perinecrotic tissue detected by immunohistochemistry with anti-CD18 antibody, and accumulation detected by myeloperoxidase (MPO, DeltaAbs/min/g) increased from 6 to 24 h (292 +/- 25 to 605 +/- 44; P < 0.05 24 h versus 6 h group; and 55 +/- 7 to 96 +/- 5; P < 0.05 24 h versus 6 h group), respectively. In in vitro analysis, PMN adherence (mm(2) endothelium) to postischemic LAD increased from 98 +/- 2 to 125 +/- 3 (P < 0.05 24 h versus 6 h group) and maximal LAD endothelium-dependent relaxation (%) impaired from 6 to 24 h (74 +/- 7 to 42 +/- 10; P < 0.05 24 h versus 6 h group). Intravenous Ado (140 microg/kg/min) for 2 h at R reduced infarct size (17 +/- 2; P < 0.05 Ado versus 6 h group), CD18 positive cells (130 +/- 10; P < 0.05 Ado versus 6 h group), MPO (14 +/- 3; P < 0.05 Ado versus 6 h group), PMN adherence (57 +/- 2; P < 0.05 Ado versus 6 h group), and augmented LAD vascular relaxation (102 +/- 5 versus 74 +/- 7; P < 0.05 Ado versus 6 h group). However, this protection by Ado was lost when R was extended to 24 h. Treatment with multiple infusion of Ado at 2, 6, 12, and 18 h R significantly preserved protective effects seen at 6 h R in the Ado group. Protection by multidose Ado was still preserved when R was extended to an additional 24 h. These data suggest that interventions aiming at permanently reducing R injury may thus need to be administered not only at early R, but also during late phase. A slow wave of PMN accumulation at late R may be involved in the extension of infarction and endothelial dysfunction.

Inhibition of myocardial injury by ischemic postconditioning during reperfusion: comparison with ischemic preconditioning

Ischemic preconditioning (Pre-con) is an adaptive response triggered by a brief ischemia applied before a prolonged coronary occlusion. We tested the hypothesis that repetitive ischemia applied during early reperfusion, i.e., postconditioning (Post-con), is cardio-protective by attenuating reperfusion injury. In anesthetized open-chest dogs, the left anterior descending artery (LAD) was occluded for 60 min and reperfused for 3 h. In controls (n = 10), there was no intervention. In Pre-con (n = 9), the LAD was occluded for 5 min and reperfused for 10 min before the prolonged occlusion. In Post-con (n = 10), at the start of reperfusion, three cycles of 30-s reperfusion and 30-s LAD reocclusion preceded the 3 h of reperfusion. Infarct size was significantly less in the Pre-con (15 +/- 2%, P < 0.05) and Post-con (14 +/- 2%, P < 0.05) groups compared with controls (25 +/- 3%). Tissue edema (% water content) in the area at risk was comparably reduced in Pre-con (78.3 +/- 1.2, P < 0.05) and Post-con (79.7 +/- 0.6, P < 0.05) versus controls (81.5 +/- 0.4). Polymorphonuclear neutrophil (PMN) accumulation (myeloperoxidase activity, Deltaabsorbance.min-1.g tissue-1) in the area at risk myocardium was comparably reduced in Post-con (10.8 +/- 5.5, P < 0.05) and Pre-con (13.4 +/- 3.4, P < 0.05) versus controls (47.4 +/- 15.3). Basal endothelial function measured by PMN adherence to postischemic LAD endothelium (PMNs/mm2) was comparably attenuated by Post-con and Pre-con (15 +/- 0.6 and 12 +/- 0.6, P < 0.05) versus controls (37 +/- 1.5), consistent with reduced expression of P-selectin on coronary vascular endothelium in Post-con and Pre-con. Endothelial function assessed by the maximal vasodilator response of postischemic LAD to acetylcholine was significantly greater in Post-con (104 +/- 6%, P < 0.05) and Pre-con (109 +/- 5%, P < 0.05) versus controls (71 +/- 8%). Plasma malondialdehyde (microM/ml), a product of lipid peroxidation, was significantly less at 1 h of reperfusion in Post-con (2.2 +/- 0.2, P < 0.05) versus controls (3.2 +/- 0.3) associated with a decrease in superoxide levels revealed by dihydroethidium staining in the myocardial area at risk. These data suggest that Post-con is as effective as Pre-con in reducing infarct size and preserving endothelial function. Post-con may be clinically applicable in coronary interventions, coronary artery bypass surgery, organ transplantation, and peripheral revascularization where reperfusion injury is expressed.

Inhibition of myocardial apoptosis reduces infarct size and improves regional contractile dysfunction during reperfusion

OBJECTIVE

Myocardial apoptosis is primarily triggered during reperfusion (R) through various mechanisms that may involve endonuclease to cleavage genomic DNA in the internucleosomal linker regions. However, the relative contribution of myocardial apoptosis to development of myocardial injury during R remains unknown. In the present study, we examined whether inhibition of apoptosis with aurintricarboxylic acid (ATA), an endonuclease inhibitor, during R reduces infarct size and improves regional contractile function.

METHODS AND RESULTS

In two groups of chronically-instrumented dogs, 1 h of left anterior descending (LAD) coronary occlusion was followed by 24 h of R with infusion of saline (control, n=8) or ATA (1 mg/kg/h, n=8) into the left atrium starting 5 min before R and continuing for 2 h. ATA significantly reduced apoptotic cells (TUNEL staining) in the peri-necrotic myocardium (12+/-1%* vs. 36+/-4%), consistent with the absence of DNA laddering. To confirm inhibition of apoptosis with ATA, densitometrically, Bcl-2 (% of normal myocardium) was significantly increased vs. control (102+/-12* vs. 68+/-9) and Bax as well as the activated caspase-3 were significantly reduced vs. control (108+/-17* vs. 194+/-42 and -29+/-4* vs. 174+/-43, respectively). ATA significantly improved segmental shortening (3.3+/-1.2* vs. -1.8+/-0.7%) and segmental work (79.3+/-11.3* vs. 7.1+/-5.8 mmHg/mm) in area at risk myocardium, and reduced infarct size (TTC staining, 27+/-0.2* vs. 37+/-0.5%), confirmed by lower plasma creatine kinase activity. In addition, myocardial blood flow (0.9+/-0.1* vs. 0.4+/-0.1 ml/min/g) and endothelial-dependent maximal vascular relaxation (119+/-6* vs. 49+/-8%) were significantly improved. Myeloperoxidase activity in area at risk myocardium, a marker for neutrophil accumulation, was also significantly reduced (17+/-4* vs. 138+/-28 Delta Abs/min).

CONCLUSIONS

These data suggest that the inhibition of apoptosis during R is associated with a reduction in infarction, improvement in regional contractile and vascular endothelial functions as well as augmentation in myocardial blood flow. *P<0.05 vs. control group.

Cholesterol enrichment upregulates intercellular adhesion molecule-1 in human vascular endothelial cells

Hypercholesterolemia is a major risk factor for atherosclerosis, but the mechanism by which cholesterol activates the endothelium remains undocumented. The present investigation was undertaken to investigate the role of cholesterol, one of the bioactive moieties of the low-density lipoprotein (LDL) particle, in initiating of intracellular signaling in endothelial cells (ECs) and culminating in increased abundance of the intercellular adhesion molecule-1 (ICAM-1). Cholesterol was delivered to human umbilical vein ECs (HUVECs) via cholesterol-enriched liposomes. In HUVECs, the cellular cholesterol:phospholipid ratio increased after 1 h of exposure to cholesterol. The level of ICAM-1 increased in both mRNA and protein after 24 h of cholesterol exposure. ICAM-1 mRNA half-life was not affected by cholesterol exposure. Promoter studies showed greater than two-fold activation of the ICAM-1 gene expression after cholesterol exposure. Electrophoretic mobility shift assay showed that activator protein-1 (AP-1) activity substantially increased after 2 h of exposure to cholesterol. In contrast, cholesterol did not affect nuclear factor-kappaB (NF-kappaB) activity. Results of trans-reporting assay revealed 2.5-fold increased expression of the AP-1-dependent reporter gene after cholesterol exposure whereas NF-kappaB-dependent expression was not affected. The AP-1/Ets (-891 to -908) site, one of the three AP-1-like sites in the ICAM-1 promoter, was most responsive to cholesterol. These data demonstrate for the first time that cholesterol enrichment phenotypically modulates ECs by transcriptionally upregulating ICAM-1 expression.

[Experimental studies of antitumor effect of artesunate on liver cancer]

OBJECTIVE

To observe the inhibiting effect of Artesunate on liver cancer in vitro and in vivo.

METHOD

The mice bearing H22 solid and ascitic liver tumor were applied in vivo experiments. Microculture tetrazolium assay and colony-forming unit assay were applied to test the cytotoxicity to human hepatocarcinoma SMMC-7721 cell line in vitro.

RESULT

The growth of solid tumor were obviously inhibited by Artesunate at the dose of 300 mg.kg-1.d-1 ig for 7 days. The tumor inhibiting rates of Artesunate were 49.1%, 48.7%, 46.6% in 3 experiments respectively. After administration of Artesunate, the survival rate of the mice bearing H22 ascitic liver tumor were increased to 45%. Compared with the control groups, the difference was statistically significant (P < 0.01). In additional, Artesunate can synergize the antitumor activity of 5-fluorouracil. Artesunate showed evident cytotoxicity to human hepatocarcinoma SMMC-7721 cells, the IC50 of Artesunate being 2.07 micrograms.ml-1 in MTT experiment and 2.48 micrograms.ml-1 in colony-forming unit experiment.

CONCLUSION

Artesunate has marked antitumor activity in vitro and in vivo.

Endoscopic thoracic sympathetic block by clipping for palmar and axillary hyperhidrosis in children and adolescents

Endoscopic thoracic sympathectomy or sympathicotomy is a safe and effective method of treating primary hyperhidrosis (PH), but postoperative compensatory sweating may be a problem. There are few reports of sympathetic blockade by clipping for PH. We present our experience of endoscopic thoracic sympathetic block (ETSB) by clipping in treating palmar (PAH) and axillary hyperhidrosis (AH) in children and adolescents. Between May 1997 and June 1998, a total of 78 patients with PAH or AH underwent ETSB by clipping using an 8-mm, 0 degrees thoracoscope. There were 33 males and 45 females with a mean age of 14.1 years (range 9-16 y). All patients were placed in a semi-sitting position under single-lumen intubation anesthesia; 52 patients with PAH underwent T2 sympathetic block by clipping at the 2nd and 3rd rib beds, and T3 and T4 sympathetic block was performed at the 3rd, 4th and 5th rib beds in 26 patients with AH. A total of 156 sympathetic blocks by clipping were achieved. The operation was usually accomplished within 20 min (range 16-30 min). Most patients were discharged within 4 h after the operation. There were neither surgical complications nor mortality. The mean postoperative follow-up period was 32.7 months (range 26-40). Improvement of PAH or AH could be obtained in all cases; 70 patients (85.4%) developed compensatory sweating of the trunk and lower limbs. One patient with PAH underwent a reverse operation with improvement of the sweating 14 days after removal of the endo-clips. ETSB by clipping is thus a safe and effective method for treating PH in children and adolescents; compensatory sweating may be improved after a reverse operation with removal of the endo-clip.

Progressively developed myocardial apoptotic cell death during late phase of reperfusion

Myocardial apoptosis is primarily triggered during reperfusion (R). The aim of this study was to test the hypothesis that R-induced apoptosis develops progressively during the late phase of R, and that R-induced apoptosis is associated with changes in expression of anti- and pro-apoptotic proteins and infiltrated inflammatory cells. Thirty-one dogs were subjected to 60 min of left anterior descending coronary occlusion followed by 6, 24, 48, and 72 h R, respectively. There was no group difference in collateral blood flow, measured by colored microspheres during ischemia. Necrotic cell death (TTC staining) was significantly increased during R, starting at 27 +/- 2% at 6 h R and increasing to 41 +/- 2% at 24 h R. There was no further change at 48 (37 +/- 3%) and 72 (36 +/- 6%) h R, respectively. TUNEL positive cells (% total normal nuclei) in the peri-necrotic zone progressively increased from 6 (26 +/- 2) to 24 (38 +/- 1), 48 (48 +/- 3) and 72 (59 +/- 4) h R, respectively. The number of detected TUNEL positive cells at these time points was consistent with an increased intensity of DNA ladders, identified by agarose gel electrophoresis. Compared with normal tissue, western blot analysis showed persistent reduction in expression of anti-apoptotic protein Bcl-2 from 6 (16 +/- 0.8%) to 72 h R (78 +/- 2%), and increase in expression of pro-apoptotic proteins including Bax from 6 (30 +/- 3%) to 72 h R (66 +/- 3%), and p53 from 6 (12 +/- 1%) to 72 h R (91 +/- 2%), respectively. Immunohistochemical staining revealed that infiltrated neutrophils (mm(2) myocardium) were significantly correlated with development of necrotic and apoptotic cell death from 6 to 24 h R, respectively (P < 0.05), while large macrophage infiltration seen during 48 to 72 h R were correlated with apoptotic cell death (P < 0.05). These results indicate that 1) necrosis peaked at 24 h R when apoptosis was still progressively developing during later R; 2) changes in Bcl-2 family and p53 proteins may participate in R-induced myocardial apoptosis; 3) inflammatory cells may play a role in triggering cell death during R. P < 0.05 vs. normal nuclei and tissue; P < 0.01 vs. 6 h R.

Evidence for alterations in circulating low-molecular-weight antioxidants and increased lipid peroxidation in smokers on hemodialysis

BACKGROUND/AIM

Cardiovascular disease is the major cause of mortality in dialysis patients, accounting for about 40% of deaths in most large registries. Oxidative stress has been strongly implicated in the pathogenesis of these events. As end-stage renal disease is a state of elevated free radical activity, the aim of the present study was to investigate the negative impact of smoking in 57 male hemodialysis patients.

METHODS

The patients, who were 20-85 years of age (mean age 51.0 +/- 14 years), had been on hemodialysis for at least 6 months before participating in this study. Fasting blood sampling for serum lipid, albumin, urate and lipophilic antioxidants such as tocopherols, carotenes, ascorbate and lipid peroxides was performed.

RESULTS

The plasma malondialdehyde (MDA) concentration was significantly higher in hemodialysis patients who smoked compared to hemodialysis patients who were nonsmokers (1.92 +/- 0.52 vs. 1.59 +/- 0.42 nmol/ml, p = 0.006). No association was found between levels of MDA in smokers and parameters such as body mass index, serum cholesterol, serum triglycerides and smoking index. There were no significant differences in the plasma levels of uric acid, alpha-tocopherol, gamma-tocopherol, delta-tocopherol, alpha-carotene, beta-carotene and retinol between the two groups. A significantly lower level of plasma ascorbate was observed in hemodialysis patients who smoked compared to the nonsmoking hemodialysis patients or healthy controls (4.59 +/- 4.0 vs. 9.57 +/- 4.0 and 10.16 +/- 4.6 microg/ml, p < 0.05). Moreover, in smokers, the plasma levels of ascorbate were negatively correlated with the levels of plasma MDA (r = -0.43, p < 0.001) of each patient. Partial correlation analysis of the plasma levels of the measured antioxidants and the smoking index revealed a negative correlation between the plasma levels of lipid-normalized lycopene and the smoking index (r = -0.53, p < 0.05).

CONCLUSION

Our data suggest that cigarette smoking further increases plasma-circulating products of lipid peroxidation, which are already increased in nonsmoking hemodialysis patients as compared to matched healthy controls. The lower plasma levels of ascorbate in hemodialysis patients who smoke suggest that these patients may be more susceptible to oxidative tissue damage caused by smoking.

Video-assisted thoracoscopic T2 sympathetic block by clipping for palmar hyperhidrosis: analysis of 52 cases

BACKGROUND

Endoscopic thoracic sympathectomy or sympathicotomy is a standard method in treating palmar hyperhidrosis, but postoperative compensatory sweating may be troublesome in some patients. Therefore, we designed a new technique for only T2 sympathetic blocking by clipping instead of interruption of the sympathetic trunk.

PATIENTS AND METHODS

Between September 2000 and July 2001, we saw a total of 100 patients with palmar hyperhidrosis who underwent video-assisted thoracoscopic sympathetic blocking of the T2 ganglion. All patients were placed in a semisitting position under single-lumen intubated anesthesia. We performed sympathetic blocking by clipping of the T2 ganglion at the level of the second and third rib beds using an 8-mm, 0 degree thoracoscope (Storz).

RESULTS

We supposed that the postoperative improvement in palmar hyperhidrosis would be perfect. The operation could be accomplished within 30 minutes. All patients were discharged within 4 hours after the operation. Surgical complications were minimal, without surgical mortality. A few patients were willing to receive the reverse operation and should get improvement of compensatory sweating after removal of the endo clips.

CONCLUSION

We believe that video-assisted thoracoscopic T2 sympathetic block by clipping will be a safe and effective method of treating patients with palmar hyperhidrosis. Compensatory sweating may be improved by the reverse operation: removal of the endo clip.

Use of isomalto-oligosaccharide in the treatment of lipid profiles and constipation in hemodialysis patients

Chronic constipation and hyperlipidemia, one of the many atherogenic risk factors, were common complications in hemodialysis (HD) patients. The present trial evaluates the therapeutic efficacy of isomaltose-oligosaccharide (IMO) in the treatment of chronic severe constipation and its effect on lipid profiles in 20 HD patients. After a 2-week basal period, these patients were allocated to receive 30 g of IMO for a 4-week period. After the study period, these patients were observed for another 4 weeks. Bowel frequency, gastrointestinal symptomatology, biochemical parameters, and lipid profiles were assessed. All patients completed this study. IMO induced a significant increase in number of bowel movements and hence improvement of constipation in 76.3% + 30.9% of patients during the 4-week treatment. Some, but well-tolerated gastrointestinal side effects were noted. Statistically significant decreases in total cholesterol and triglycerides (TG) and increases in high density lipoprotein-cholesterol (HDL-C) were noted after IMO treatment (P <.05 compared with baseline and controls). After the study period, those patients receiving IMO had reductions in levels of total cholesterol -17.6%, TG -18.4%, and elevations of levels of HDL-C by +39.1%. In conclusion, IMO once a day is well tolerated and effective in increasing bowel frequency and improving constipation in HD patients. In addition, IMO treatment was effective in lowering total cholesterol and triglycerides and in raising HDL-C in HD patients.

Pitfalls and complication avoidance associated with transthoracic endoscopic sympathectomy for primary hyperhidrosis (analysis of 2200 cases)

BACKGROUND

Transthoracic endoscopic sympathectomy (TES) has been already a standard method for the treatment of primary hyperhidrosis. There are rare reports about possibly encountered problems during TES. Therefore, we present our experience in treating palmar and axillary hyperhidrosis and discuss the resoluble methods of potential problems during and after TES.

PATIENTS AND METHODS

From June 1994 to October 1999, there were 2200 patients with palmar or axillary hyperhidrosis underwent TES. There are 926 males and 1274 females. Their mean age was 23.4 years old (range: 5-65). All except 12 patients were placed in half-sitting position under single or double-lumen intubation anesthesia. Either a 6-mm or 8-mm, 0degrees thoracoscope, (Karl Storz, Germany) was used to perform sympathectomy thru 0.8 cm incisions below each axilla. Ablation of T2 ganglion was performed in treating patients with palmar hyperhidrosis. Ablation of T3 and T4 ganglia was performed for patients with axillary hyperhidrosis. All except 22 patients were discharged 4 hours after TES, and returned to their activities within one week.

RESULT

Successful sympathectomy were achieved up to 2178 patients (99%), but the rates of incidental unusual findings and possibly encountered problems during TES were 5.6% and 7.1% alternatively. Surgical complications included pneumothorax (10 patients, 0.45%), Hemothorax (2 patients, 0.09%) segmental atelectasis (12 patients, 0.55%), mild wound infection (3 patients, 0.14%) and compensatory sweating (1936 patients, 88%). There was no surgical mortality case. But pleural adhesion (54 patients, 2.45%), repeat sympathectomy (27 patients, 1.23%), obscured upper sympathetic trunk by adipose tissue (22 patients, 1%), medially located sympathetic trunk (18 patients, 0.81%), great vessels overriding or close to the sympathetic trunk (15 patients, 0.68%), aberrant vessels (3 patients, 0.14%), transient bradycardia (3 patients, 0.14%) and re-expansion pulmonary edema (1 patient, 0.05%) might occur during TES.

CONCLUSION

Potential complications may happen during and after TES. But nearly all endoscopic sympathectomy could be achieved if surgeons acknowledge possible anatomic variation and has ability to overcome pleural adhesions.

Adenosine attenuates reperfusion-induced apoptotic cell death by modulating expression of Bcl-2 and Bax proteins

This study tests the hypothesis that infarct reduction with adenosine (Ado) is associated with inhibition of apoptotic cell death by modulating expression of anti-apoptotic Bcl-2 and pro-apoptotic Bax proteins and reducing neutrophil accumulation. In three groups of dogs, the left anterior descending coronary artery was occluded for 60 min and reperfused for 6 h. Either saline (Control, n=8), Ado (140 microg/kg/min, n=8) or CGS21680, an adenosine A2A receptor analogue, (0.2 microg/kg/min, n=7) were infused during the first 2 h of reperfusion. Myocardial apoptosis was detected by histological TUNEL staining and DNA laddering. Expression of Bcl-2 and Bax proteins was analyzed using Western blot assay. Neutrophil localization was detected by immunohistochemistry with monoclonal anti-neutrophil CD18 antibody. There was no group difference in collateral blood flow (colored microspheres) during ischemia. Intra-left atrial administration of Ado and CGS21680 significantly decreased infarct size from 26+/-2% in Control to 13+/-1%* and 16+/-3%*, respectively. TUNEL positive cells in the peri-necrotic zone of the ischemic myocardium were also significantly reduced from 16+/-2% in Control group to 9+/-1%* and 10+/-2%*, respectively, consistent with the absence of DNA laddering in these two groups. Densitometrically, Ado and CGS21680 at reperfusion significantly increased the expression (% of normal myocardium) of downregulated Bcl-2 from 45+/-6% in Control group to 78+/-12%* and 69+/-10%*, respectively, and attenuated expression of upregulated Bax from 198+/-16% in Control group to 148+/-10%* and 158+/-12%*, respectively. Furthermore, the number of positive CD18 cells (mm(2) myocardium), which was significantly correlated with TUNEL positive cells in peri-necrotic zone, was significantly reduced from 403+/-42 in Control group to 142+/-18* in Ado group and 153+/-20%* in CGS21680 group, respectively. In conclusion, the present study suggests that inhibition of apoptosis by Ado at reperfusion involves alterations in anti-apoptotic Bcl-2 and pro-apoptotic Bax proteins and neutrophil accumulation, primarily mediated by an adenosine A2A receptor. * P<0.05 v Control group.

The study of TSP, PM(2.5-10) and PM2.5 during Taiwan Chi-Chi Earthquake in the traffic site of central Taiwan, Taichung

Ambient particle concentration was taken on the traffic sampling site over the Chung-Chi Road over bridge (CCROB) in front of Hungkuang Institute of Technology (HKIT). The sampling time was from August 1999 to December 1999. During the sampling period, Taiwan's biggest earthquake in more than a century registered 7.3 on the Richter scale (Taiwan Chi-Chi Earthquake). Besides, there were more than 20,000 aftershocks that followed the Taiwan Chi-Chi Earthquake within three months. Thus, the PM2.5, PM(2.5-10) particle concentrations were also collected then and compared with total suspended particle (TSP) in this study. The average PM(2.5-10), PM2.5 and TSP concentrations are 24.6, 58.0 and 106 microg/m3, respectively, after the Taiwan Chi-Chi Earthquake. The average TSP concentrations before and after Taiwan Chi-Chi Earthquake were 70 and 127 microg/m3, respectively. It is clearly shown that the average concentration of TSP after Taiwan Chi-Chi Earthquake was about 1.8 times as that of TSP concentration before Taiwan Chi-Chi Earthquake in the traffic site of central Taiwan. And the ratios of PM2.5/PM(2.5-10), PM2.5/PM10 and PM2.5/TSP are 2.2%, 67.2%, 38.9%, respectively. The results also indicated about Chi-Chi fine particle concentration (PM25) and the TSP increases in the traffic site of central Taiwan after Taiwan Chi-Chi Earthquake.

Dynamic progression of contractile and endothelial dysfunction and infarct extension in the late phase of reperfusion

BACKGROUND

Myocardial injury during early reperfusion (R) has been well documented. However, the extent and time course of myocardial injury during late R are still unclear. The purpose of this study was to determine the extent of regional contractile and endothelial dysfunction and myocardial blood flow (MBF) defect as well as extension of infarction in association with neutrophil (PMN) actions during R.

MATERIALS AND METHODS

A total of 29 dogs underwent a protocol of 1 h LAD ischemia followed by 6, 24, 48, and 72 h of R, respectively. Regional contractile function (sonomicrometry), MBF (colored microspheres), infarct size (triphenyltetrazolium chloride staining), and PMN localization (immunohistochemistry) were determined.

RESULTS

Percentage segmental shortening at 6, 24, 48, and 72 h of R was significantly blunted (-1.8 +/- 1.2,* - 0.37 +/- 0. 6,* 0.04 +/- 0.2,* and 5.9 +/- 1.2* vs baseline 17.7 +/- 0.8). MBF (ml/min/g) was attenuated at 24 (0.27 +/- 0.03*), 48 (0.46 +/- 0. 07*), and 72 h of R (0.48 +/- 0.06*) vs 6 h of R (0.65 +/- 0.06). Infarct size increased from 6 (27 +/- 2%) to 24 h of R (41 +/- 2%*) with no further increase at 48 and 72 h of R, consistent with a peak of creatine kinase activity. PMN adherence (mm(2) endothelium) to left anterior descending coronary artery (LAD) segments was increased after 6 h of R (63 +/- 3*) vs nonischemic left circumflex coronary artery (LCX) segments (42 +/- 2) with a peak at 48 h of R (111 +/- 5*). Endothelium-dependent vascular relaxation in the LAD was also blunted at 6, 24, and 48 h of R. Immunostaining revealed CD18-positive PMNs were mainly accumulated in intravascular space during 6 h of R with an increase in migration of PMNs seen at 24 h of R, consistent with a peak of myeloperoxidase release. Myeloperoxidase activity in a given area at risk sample was significantly correlated with infarct extension during the first 24 h of R.

CONCLUSIONS

These results provide pathologic evidence for myocardial injury during the extended R and a basis for exploration of interventions designed to limit myocardial injury after ischemia. (*P < 0.05 vs Baseline, 6 h of R and LCX segments.)

Glutathione Reverses Endothelial Damage From Peroxynitrite, the Byproduct of Nitric Oxide Degradation, in Crystalloid Cardioplegia

Background —NO has been advocated as an adjunct to cardioplegia solutions. However, NO undergoes a rapid biradical reaction with superoxide anions to produce peroxynitrite (ONOO − ). ONOO − in crystalloid cardioplegia solution induces injury to coronary endothelium and to systolic function after cardioplegia and reperfusion. However, ONOO − may be degraded to less lethal or cardioprotective intermediates with glutathione (GSH) in reactions separate from its well known antioxidant effects. We hypothesized that GSH detoxifies ONOO − and reverses defects in endothelial function and systolic function when present in crystalloid cardioplegia.

Methods and Results —In anesthetized dogs on cardiopulmonary bypass, a 45-minute period of global normothermic ischemia was followed by 60 minutes of intermittent cold crystalloid cardioplegia (Plegisol) and 2 hours of reperfusion. The cardioplegia solution contained 5 μmol/L authentic ONOO − ; catalase was included to attenuate the potential antioxidant effects of GSH and to unmask the effects on ONOO − . In 1 group (CP+GSH, n=5), the cardioplegia contained 500 μmol/L GSH, whereas 1 group received crystalloid cardioplegia without GSH (CCP, n=6). There were no group differences in postcardioplegia left ventricular systolic function (end-systolic pressure-volume relation, impedance catheter: CCP 10.0±2.4 versus CP+GSH 10.6±1.3 mm Hg/mL) or diastolic chamber stiffness (β-coefficient: CCP 0.35±0.2 versus CP+GSH 0.31±0.18). Myocardial neutrophil accumulation (myeloperoxidase activity) was attenuated in CP+GSH versus CCP (2.2±0.7 versus 5.4±1.2, P <0.05). In postexperimental coronary arteries, maximal endothelium-dependent relaxation was greater in CP+GSH than in CCP (118±6% versus 92±5%, P <0.05), with a smaller EC 50 value (−7.10±0.05 versus −6.98±0.03, respectively, P <0.05). Smooth muscle relaxation was complete in both groups. The adherence of neutrophils to postexperimental coronary arteries as a measure of endothelial function was less in CP+GSH than in CCP (98±18 versus 234±36 neutrophils/mm 2 , P <0.05). Nitrosoglutathione, a byproduct of the reaction between ONOO − and GSH, was greater in CP+GSH than in CCP (4.1±2.3 versus 0.4±0.2 μg/mL, P <0.05).

Conclusions —GSH in crystalloid cardioplegia detoxifies ONOO − and forms cardioprotective nitrosoglutathione, resulting in attenuated neutrophil adherence and selective endothelial protection through the inhibition of neutrophil-mediated damage.

Glutathione reverses endothelial damage from peroxynitrite, the byproduct of nitric oxide degradation, in crystalloid cardioplegia

BACKGROUND

NO has been advocated as an adjunct to cardioplegia solutions. However, NO undergoes a rapid biradical reaction with superoxide anions to produce peroxynitrite (ONOO(-)). ONOO(-) in crystalloid cardioplegia solution induces injury to coronary endothelium and to systolic function after cardioplegia and reperfusion. However, ONOO(-) may be degraded to less lethal or cardioprotective intermediates with glutathione (GSH) in reactions separate from its well known antioxidant effects. We hypothesized that GSH detoxifies ONOO(-) and reverses defects in endothelial function and systolic function when present in crystalloid cardioplegia.

METHODS AND RESULTS

In anesthetized dogs on cardiopulmonary bypass, a 45-minute period of global normothermic ischemia was followed by 60 minutes of intermittent cold crystalloid cardioplegia (Plegisol) and 2 hours of reperfusion. The cardioplegia solution contained 5 micromol/L authentic ONOO(-); catalase was included to attenuate the potential antioxidant effects of GSH and to unmask the effects on ONOO(-). In 1 group (CP+GSH, n=5), the cardioplegia contained 500 micromol/L GSH, whereas 1 group received crystalloid cardioplegia without GSH (CCP, n=6). There were no group differences in postcardioplegia left ventricular systolic function (end-systolic pressure-volume relation, impedance catheter: CCP 10.0+/-2.4 versus CP+GSH 10.6+/-1.3 mm Hg/mL) or diastolic chamber stiffness (ss-coefficient: CCP 0.35+/-0.2 versus CP+GSH 0.31+/-0.18). Myocardial neutrophil accumulation (myeloperoxidase activity) was attenuated in CP+GSH versus CCP (2.2+/-0.7 versus 5.4+/-1.2, P:<0.05). In postexperimental coronary arteries, maximal endothelium-dependent relaxation was greater in CP+GSH than in CCP (118+/-6% versus 92+/-5%, P:<0.05), with a smaller EC(50) value (-7. 10+/-0.05 versus -6.98+/-0.03, respectively, P:<0.05). Smooth muscle relaxation was complete in both groups. The adherence of neutrophils to postexperimental coronary arteries as a measure of endothelial function was less in CP+GSH than in CCP (98+/-18 versus 234+/-36 neutrophils/mm(2), P:<0.05). Nitrosoglutathione, a byproduct of the reaction between ONOO(-) and GSH, was greater in CP+GSH than in CCP (4.1+/-2.3 versus 0.4+/-0.2 microg/mL, P:<0.05).

CONCLUSIONS

GSH in crystalloid cardioplegia detoxifies ONOO(-) and forms cardioprotective nitrosoglutathione, resulting in attenuated neutrophil adherence and selective endothelial protection through the inhibition of neutrophil-mediated damage.

Comparison of particulate mass, chemical species for urban, suburban and rural areas in central Taiwan, Taichung

Aerosol samples for PM2.5, PM(2.5-10) and TSP were collected from June to September 1998 and from February to March 1999 in central Taiwan. Ion chromatography was used to analyze the acidic anions: sulfate, nitrate and chloride in the Universal samples. The ratios of fine particle concentrations to coarse particle concentrations displayed that the fine particle concentrations are almost greater than that of coarse particle concentrations in Taichung area. The average concentrations of PM2.5, PM(2.5-10) and TSP in urban sites are higher than in suburban and rural sites at both daytime and night-time. Chloride dominated in the coarse mode in daytime and in fine mode in night-time. Nitrate can be found in both the coarse and fine modes. Sulfate dominated in fine mode in both daytime and night-time.

Hypothermic circulatory arrest causes multisystem vascular endothelial dysfunction and apoptosis

BACKGROUND

Multiple organ failure after deep hypothermic circulatory arrest (DHCA) may occur secondary to endothelial dysfunction and apoptosis. We sought to determine if DHCA causes endothelial dysfunction and apoptosis in brain, kidney, lungs, and other tissues.

METHODS

Anesthetized pigs on cardiopulmonary bypass were: (1) cooled to 18 degrees C, and had their circulation arrested (60 minutes) and reperfused at 37 degrees C for 90 minutes (DHCA, n = 8); or (2) time-matched normothermic controls on bypass (CPB, n = 6). Endothelial function in cerebral, pulmonary, and renal vessels was assessed by vasorelaxation responses to endothelial-specific bradykinin (BK) or acetylcholine (ACh), and smooth muscle-specific nitroprusside.

RESULTS

In vivo transcranial vasorelaxation responses to ACh were similar between the two groups. In small-caliber cerebral arteries, endothelial relaxation (BK) was impaired in CPB vs DHCA (maximal 55% +/- 2% [p < 0.05] vs 100% +/- 6%). Pulmonary artery ACh responses were comparable between CPB (110% +/- 10%) and DHCA (83% +/- 6%), but responses in pulmonary vein were impaired in DHCA (109% +/- 3%, p < 0.05) relative to CPB (137% +/- 6%). In renal arteries, endothelial (ACh) responses were impaired in DHCA (71% +/- 13%) relative to CPB (129% +/- 14%). Apoptosis (DNA laddering) occurred primarily in duodenal tissue, with a greater frequency in DHCA (56%, p < 0.05) compared with normothermic CPB (17%) and nonbypass controls (0%).

CONCLUSIONS

DHCA is associated with endothelial dysfunction in cerebral microvessels but not in the in vivo transcranial vasculature; in addition, endothelial dysfunction was noted in large-caliber renal arteries and pulmonary veins. DHCA is also associated with duodenal apoptosis. Vascular endothelial dysfunction and apoptosis may be involved in the pathophysiology of multisystem organ failure after DHCA.

Preconditioning decreases Bax expression, PMN accumulation and apoptosis in reperfused rat heart

OBJECTIVE

Recent studies suggest that ischemic preconditioning (IPC) inhibits myocardial apoptosis after ischemia and reperfusion. This study tested the hypothesis that IPC reduces ischemia/reperfusion-induced myocardial apoptosis by inhibiting neutrophil (PMN) accumulation and altering expression of Bcl-2 and Bax proteins.

METHODS

Eighteen rats were subjected to 30 min of left coronary artery occlusion followed by 180 min of reperfusion with IPC (5 min ischemia and 10 min of reperfusion, n = 10) or without IPC (n = 8). Myocardial apoptosis was detected histologically using the terminal transferase UTP nick end labeling (TUNEL) assay and confirmed by DNA ladder on agarose gel electrophoresis. PMN accumulation was detected immunohistochemically with anti-rat CD18 antibody (WT3) and expression of Bcl-2 and Bax proteins was analyzed using Western blot assay.

RESULTS

IPC significantly decreased TUNEL positive cells (% total nuclei) in the ischemic zone from 28.6 +/- 2.8 to 3.4 +/- 0.9 (P < 0.05), consistent with the absence of DNA ladders in the IPC group. IPC significantly attenuated PMN accumulation (cells/mm2 myocardium) in the ischemic zone from 243 +/- 19 to 118 +/- 19 (P < 0.05). By regression analysis, there was a significant correlation between TUNEL positive cells and accumulated CD18 positive PMNs in the ischemic zone (r = 0.8, P < 0.001), which was shifted downward by IPC. Densitometrically, IPC significantly attenuated the ischemia/reperfusion-upregulated expression of Bax protein in the ischemic zone from 204 +/- 57% in the control group to 76 +/- 7% (P < 0.05), while the expression of Bcl-2 was not different from the non-ischemic zone in either group.

CONCLUSION

These data suggest that ischemic preconditioning may reduce myocardial apoptosis by inhibiting PMN accumulation and down-regulating expression of Bax.

Reperfusion induces myocardial apoptotic cell death

OBJECTIVE

The purpose of the present study was to investigate whether apoptosis is triggered during ischemia (I) and reperfusion (R) and whether I/R-induced apoptosis is correlated with changes in expression of Bcl-2 and Bax.

METHODS

Anesthetized open-chest dogs were divided into two groups. Group I: 7 h of permanent I without R (PI, n = 7); Group II: 60 min I followed by 6 h R (I/R, n = 8). Apoptosis was identified as "DNA ladder" by agarose gel electrophoresis or confirmed histologically using the terminal transferase UTP nick end labeling (TUNEL) assay.

RESULTS

Collateral myocardial coronary blood flow during I, confirmed by colored microspheres was comparable in both groups. Although PI caused 72 +/- 5% infarct size, very few TUNEL-positive cells were detected in the necrotic area (0.2 +/- 0.1% of total normal nuclei), consistent with an absence of DNA laddering. In contrast, the appearance of TUNEL-positive cells was significantly displayed after 6 h R in the necrotic area in I/R group (26 +/- 4%, P < 0.001 vs. PI group), and DNA ladder occurred in all experimental animals, suggesting that myocardial apoptosis is primarily elicited by R. Densitometrically, Western blot analysis showed significant reduction in expression of Bcl-2 (16 +/- 1%) and increase in Bax (29 +/- 8%) after 6 h R in the necrotic area compared with normal tissue while expression of these two proteins was not changed in the PI group. Polymorphonuclear neutrophil (PMN) accumulation in the necrotic area determined either by immunohistochemistry with anti-CD18 antibody or by myeloperoxidase activity was significantly increased in the I/R group compared to the PI group (358 +/- 24 vs. 24 +/- 2, mm2 myocardium, P < 0.01) and (2.9 +/- 0.3 vs. 0.4 +/- 0.1, U/100 mg tissue, P < 0.01). There was a significant linear relationship between CD18-positive PMNs and TUNEL-positive cells (P < 0.05) in the I/R group.

CONCLUSIONS

These results indicate that (1) PI without R did not induce apoptotic cell death, while two types of cell death, necrosis and apoptosis were found after I/R, (2) the Bcl-2 family may participate in early R-induced myocardial apoptosis, (3) PMN accumulation may play a role in the development of apoptosis.

Administration of adenosine during reperfusion reduces injury of vascular endothelium and death of myocytes

INTRODUCTION

To test the hypothesis that administration of adenosine during reperfusion attenuates endothelial dysfunction and extension of infarct size by inhibiting polymorphonuclear neutrophil (PMN)-mediated events and apoptosis.

METHODS

Anesthetized dogs were subjected to 1 h coronary artery occlusion and 6 h of reperfusion with infusion of saline (vehicle, n = 8) or 140 micrograms/kg per min adenosine, n = 8) continuously into the left atrium starting 5 min before reperfusion and continuing for 2 h.

RESULTS

There was no intergroup difference in collateral myocardial blood flow measured by using colored microspheres in the area at risk during ischemia. Infusion of adenosine transiently improved segmental shortening (4.1 +/- 3.1% versus -2.5 +/- 2.3%, P < 0.05) and segmental work (41.4 +/- 22 versus 15 +/- 13 mmHg/mm, P < 0.05) after 4 h of reperfusion. Infusion of adenosine reduced size of infarct (determined by staining with triphenyltetrazolium chloride) from 27 +/- 2% with vehicle to 14 +/- 1%, (P < 0.05). This was confirmed by measuring that it lowered activity of plasma creatine kinase (from 19 +/- 2 versus 8 +/- 1 IU/g protein, P < 0.05). It also reduced the proportion of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive nuclei in the perinecrotic zone from 17.3 +/- 1.6 to 10.3 +/- 1.0% (P < 0.05) and reduced the appearance of DNA ladders in gel electrophoresis. In addition, it significantly decreased accumulation of PMN in the ischemic area (determined by immunohistochemistry with anti-CD18 antibody) and activity of cardiac myeloperoxidase compared with vehicle (439 +/- 52 versus 183 +/- 20 PMN/mm2 myocardium and 1.1 +/- 0.1 versus 2.4 +/- 0.2 U/100 mg tissue, P < 0.05, respectively). Furthermore, infusion of adenosine during reperfusion preserved vascular endothelial function expressed in terms of a decrease in adherence of PMN to postischemic coronary artery endothelium (63 +/- 3 versus 36 +/- 4 PMN/mm2 endothelium, P < 0.05, basal function) and agonist (acetylcholine)-induced endothelium-dependent relaxation (negative logarithm to base 10 of concentration (mol/l) for half-maximal effect 7.7 +/- 0.1 versus 7.2 +/- 0.1, P < 0.05, stimulated function). Infusion of adenosine directly inhibited generation of superoxide radical from canine PMN in vitro dose dependently from 27.8 +/- 6.3 to 5.8 +/- 2.1 nmol/l/5 x 10(6) PMN (P < 0.05).

CONCLUSION

Intra-atrial infusion of adenosine during reperfusion reduced accumulation of PMN in area at risk, preserved vascular endothelial function after ischemia-reperfusion by inhibiting interaction between PMN and endothelial cells, and decreased extension of infarct, possibly by limiting apoptosis.

A(3) adenosine receptor activation attenuates neutrophil function and neutrophil-mediated reperfusion injury

This study tested the hypothesis that A(3) adenosine receptors inhibit neutrophil (PMN) function and PMN-mediated reperfusion injury. 2-Chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide (Cl-IB-MECA), an A(3) agonist, did not attenuate superoxide production or myeloperoxidase release from stimulated PMNs. However, Cl-IB-MECA reduced platelet-activating factor-stimulated PMN adherence to coronary endothelium at low concentrations: 52 +/- 27, 45 +/- 10, and 87 +/- 23 PMNs/mm(2) at 0.1, 1.0, and 10 nM vs. 422 +/- 64 PMNs/mm(2) with platelet-activating factor alone. This inhibition was not blocked by A(1) (5 microM KW-3902) or A(2a) (5 microM KF-21326) antagonists: 44 +/- 3 and 43 +/- 2 PMNs/mm(2), respectively. Endothelial pretreatment with 1 nM Cl-IB-MECA reduced PMN adherence, which was reversed by the A(3) antagonist MRS-1220 (100 nM). PMN-mediated reperfusion injury was initiated in isolated rabbit hearts by infusion of 28 x 10(6) PMNs/min for 10 min early in reperfusion. PMNs caused a significant decrease in recovery of left ventricular developed pressure and positive and negative time derivatives of pressure (23 +/- 3, 25 +/- 3, and 23 +/- 3% of baseline, respectively) vs. buffer-perfused hearts (43 +/- 7, 44 +/- 7, and 45 +/- 6%, respectively). Cl-IB-MECA (10 nM) given at reperfusion attenuated the PMN-mediated loss of contractile recovery (40 +/- 3, 46 +/- 5, and 42 +/- 4% of baseline). Cl-IB-MECA reduced myeloperoxidase release activity (5.3 +/- 0.6 absorbance units/min) and CD18-positive cells (54 +/- 9 cells/slide) compared with the untreated PMN group (17.9 +/- 1.7 absorbance units/min and 183 +/- 68 cells/slide). We conclude that Cl-IB-MECA attenuates reperfusion injury by decreasing PMN-endothelial cell interactions. These results suggest that the A(3) adenosine receptor may be a novel therapeutic target for treatment of myocardial ischemia and reperfusion.

Ischemic preconditioning reduces neutrophil accumulation and myocardial apoptosis

BACKGROUND

This study tested the hypothesis that ischemic preconditioning (IP) inhibits myocardial apoptosis after a short period of ischemia and reperfusion.

METHODS

In 9 anesthetized dogs, the left anterior descending (LAD) coronary artery was occluded for 30 min and reperfused for 3 h (control), while in 9 others, LAD occlusion was preceded by 5 min of occlusion and 5 min of reperfusion (IP). DNA from frozen myocardial tissue samples was extracted, and apoptosis were identified as "ladders" by agarose gel electrophoresis or confirmed histologically using the terminal transferase UTP nick end-labeling (TUNEL) assay. Neutrophil accumulation was detected by measuring cardiac myeloperoxidase activity.

RESULTS

Thirty minutes of LAD occlusion caused a significant decrease in blood flow (colored microspheres), which was comparable between groups. In the control group, DNA ladders occurred in the area at risk (AAR) in six out nine experiments. In contrast, DNA laddering in the AAR was not observed in any of the IP group. AAR in the control group showed a greater percentage of apoptotic cells than IP (6.7 +/- 0.9% vs 1.2 +/- 0.2%; p < 0.01). Cardiac myeloperoxidase activity (U/g tissue) was significantly reduced from 0.07 +/- 0.004 in control to 0.04 +/- 0.01 in IP group (p < 0.05).

CONCLUSIONS

We conclude that ischemic preconditioning attenuates apoptosis and neutrophil accumulation in the AAR in a model of nonlethal acute ischemia and reperfusion.

Uterine epithelioid leiomyosarcoma in a pig-tailed macaque

During ultrasonographic examination following spontaneous abortion, an approximately 6-cm diameter mass of mixed echogenicity is detected in the uterine wall of a mature pig-tailed macaque (Macaca nemestrina). Grossly, the mass is associated with the uterine fundus, multilobulate and tan with red-black mottled foci on cut surface. Microscopically, the invasive mass is composed of poorly differentiated round cells arranged in sheets and bundles supported by a fine fibrous stroma. On immunohistochemical evaluation, neoplastic cells contain vimentin, desmin, muscle actin, and smooth muscle alpha-actin antigens and do not react with antibodies to low and high molecular-weight cytokeratins. Cell morphology and immunohistochemical results indicate a diagnosis of epithelioid leiomyosarcoma (clear cell variant).

Does alveolar soft-part sarcoma exhibit skeletal muscle differentiation? An immunocytochemical and biochemical study of myogenic regulatory protein expression

There has been persistent controversy regarding the nature of cell differentiation in alveolar soft-part sarcoma (ASPS) since its first description in 1952. Some studies suggest that ASPS might represent an unusual variant of skeletal muscle tumor. Given the availability of new monoclonal antibodies to probe for skeletal muscle differentiation and the rapid advance in immunocytochemical techniques for deparaffinized, formalin-fixed tissue sections, we wished to test the proposed hypothesis that ASPS might represent a new type of rhabdomyosarcoma. Twelve archival samples of ASPS were retrieved, and we investigated the expression of two myogenic regulatory proteins, MyoD1 and myogenin, as well as other muscle-associated proteins, using sensitive immunocytochemical techniques. Despite the presence of desmin immunostaining in six ASPSs, no tumors were positive for either muscle actin or myoglobin. Most importantly, no specimen showed nuclear expression of MyoD1 or myogenin. In 11 tumors, however, there was considerable granular immunostaining in the tumor cell cytoplasm with the anti-MyoD1 monoclonal antibody 5.8A, a phenomenon observed in various nonmuscle normal and neoplastic tissues with this antibody. To analyze the exact nature of immunostaining of MyoD1 and desmin in ASPS, biochemical analyses using available fresh frozen tumor tissue were performed. Although a 53-kDa band was noted with antidesmin antibody on Western blot analysis, no specific protein band that corresponds to the 45-kDa MyoD1 was detected with antibody 5.8A. These results confirm the presence of desmin in ASPS but argue against authentic expression of MyoD1. They also suggest that the cytoplasmic immunostaining observed with anti-MyoD1 antibody 5.8A most likely represents a nonspecific cross-reaction with an unknown cytoplasmic antigen. Considering the master role that MyoD1 and myogenin play in skeletal muscle commitment and differentiation and the lack of expression of these two proteins in ASPS as determined immunocytochemically and biochemically, we think that the histogenesis of ASPS remains unknown.

Expression of myogenic regulatory proteins (myogenin and MyoD1) in small blue round cell tumors of childhood

The distinction of rhabdomyosarcoma (RMS) from other small blue round cell tumors of childhood, such as Ewing's sarcoma/peripheral primitive neuroectodermal tumor (pPNET) and neuroblastoma, continues to present a diagnostic challenge to pathologists. The recent recognition of the master role of myogenic regulatory proteins in skeletal muscle commitment and differentiation, and the availability of monoclonal antibodies to two of them (myogenin and MyoD1), has prompted us to test their diagnostic utility in routinely processed, formalin-fixed, and deparaffinized tissue. Preliminary studies had demonstrated that, with the use of heat-induced epitope retrieval techniques, expression of myogenin and MyoD1 could be documented specifically in nuclei of fetal skeletal muscle by the respective antibodies. We performed a retrospective immunohistochemical analysis on 72 cases of small blue round cell tumors, including 33 RMSs, 1 metastatic myogenous Wilms' tumor, 26 Ewing's sarcomas/pPNETs, and 12 neuroblastomas. Nuclear expression of myogenin and MyoD1 were both found in 30/33 non-overlapping cases of RMS, with no significant differences in the sensitivity with respect to histological subtypes, and in 1/1 case of myogenous Wilms' tumor. None of the neuroblastomas or Ewing's sarcomas/pPNETs demonstrated positive nuclear staining with either antibody. However, most of the neuroblastomas, and occasional Ewing's sarcomas/pPNETs, showed variable fibrillary, cytoplasmic immunoreactivity with antibody to MyoD1. We conclude that, with the use of microwave-based epitope retrieval, antibodies to myogenin and MyoD1 are both useful markers for the identification of RMS among other small blue round cell tumors of childhood, but antibodies to myogenin have technical advantages over those to MyoD1, as the latter may cross-react with an unknown cytoplasmic antigen in non-muscle cells and tumors.

Purification and characterization of [3H]mepyramine (histamine H1 antagonist)-binding protein from rat liver: a highly homologous protein with cytochrome P450 2D

A protein having a high-affinity binding site for [3H]mepyramine (MBP) was purified to homogeneity from rat liver membranes. The purified MBP has a single type of binding site for [3H]mepyramine with Kd value of 18.5 nM, and its molecular weight was determined to be 56,000 by SDS polyacrylamide gel electrophoresis. Amino acid sequences of twelve tryptic peptides derived from MBP are highly homologous with those of rat debrisoquine 4-hydroxylase (cytochrome P450 2D1) and other rat P450 2D subfamily members. In immunoblotting analysis, an antibody against rat P450 2D1 stained a band corresponding to MBP with Mr of 56,000; its migration position was clearly different from that of rat P450 2D1. Substrates and inhibitors of debrisoquine 4-hydroxylase potently displace [3H]-mepyramine binding to MBP. Quinine and quinidine showed 400 and 80 times, respectively, higher affinity for MBP than for debrisoquine 4-hydroxylase. These results suggest that MBP is a novel P450 2D family member.