L-arginine improves endothelial function, independently of arginine uptake, in aortas from chronic renal failure female rats.

Endothelial cell dysfunction (ECD) is a common feature of chronic renal failure (CRF). Defective nitric oxide (NO) generation due to decreased endothelial nitric oxide synthase (eNOS) activity is a crucial parameter characterizing ECD. Decreased activity of cationic amino acid transporter-1 (CAT-1), the selective arginine transporter of eNOS, has been shown to inhibit eNOS in uremia. Recently, we failed to demonstrate a decrease in glomerular arginine transport in uremic female rats (Schwartz IF, Grupper A, Soetendorp H, Hillel O, Laron I, Chernichovski T, Ingbir M, Shtabski A, Weinstein T, Chernin G, Shashar M, Hershkoviz R, Schwartz D. Am J Physiol Renal Physiol 303: F396-F404, 2012). The current experiments were designed to determine whether sexual dimorphism which characterizes glomerular arginine transport system in uremia involves the systemic vasculature as well and to assess the effect of L-arginine in such conditions. Contractile and vasodilatory responses, ultrastructural changes, and measures of the L-arginine-NO system were performed in thoracic aortas of female rats subjected to 5/6 nephrectomy. The contractile response to KCl was significantly reduced, and acetylcholine-induced vasodilation was significantly impaired in aortas from CRF dames compared with healthy rats. Both of these findings were prevented by the administration of arginine in the drinking water. The decrease in both cGMP generation, a measure of eNOS activity, and aortic eNOS and phosphorylated eNOS abundance observed in CRF rats was completely abolished by l-arginine, while arginine transport and CAT-1 protein were unchanged in all experimental groups. Arginine decreased both serum levels of advanced glycation end products and the asymmetrical dimethylarginine/arginine ratio and restored the endothelial ultrastructure in CRF rats. In conclusion. arginine administration has a profound beneficial effect on ECD, independently of cellular arginine uptake, in CRF female rats.

Vipera aspis venom reduces lethality and down-regulates tumor necrosis factor-alpha in a rat model of LPS-induced sepsis.

OBJECTIVES: Sepsis and septic shock are major causes of morbidity and mortality in critically-ill patients. Sepsis constitutes the systemic response to infection, that is predominantly mediated by the pro-inflammatory cytokines TNF-alpha and IL-1beta. Hence, cytokine modulation provides a promising target for the treatment of sepsis. In this work we evaluated the effect of a low-dose Vipera aspis venom (VAV) vaccine on survival and cytokine serum levels in a rat model of lipopolysaccharide (LPS)-induced septic shock. METHODS: Adult male Wistar rats were given either VAV vaccine or saline, and 2 weeks later half of each group received LPS challenge, and were monitored for mortality, cytokine levels, blood count and chemistry. RESULTS: Survival rate was significantly higher in venom-treated, compared to non-vaccinated septic rats. Furthermore, VAV treatment significantly reduced LPS-associated TNF-alpha and LDH, without affecting IL-6 and IL-10 levels, and modified WBC and platelet counts. CONCLUSIONS: Our data suggest that sub-toxic doses of VAV have a protective effect against LPS-induced septic shock that may be mediated, at least partially, by the modulated TNF-alpha activity. This study thus offers a novel therapeutic approach for the attenuation of bacteremia-induced septic shock through the modulation of a central pro-inflammatory cytokine by VAV vaccination in mammals.

Effect of tumor necrosis factor-alpha on endothelial and inducible nitric oxide synthase messenger ribonucleic acid expression and nitric oxide synthesis in ischemic and nonischemic isolated rat heart.

OBJECTIVES: The present study aimed to investigate the influence of endogenous tumor necrosis factor-alpha (TNF-alpha) that was synthesized during ischemia and exogenous TNF-alpha on endothelial and inducible nitric oxide synthase (eNOS and iNOS) messenger ribonucleic acid (mRNA) expression and nitric oxide (NO) production in the isolated rat heart. BACKGROUND: Tumor necrosis factor-alpha is recognized as being a proinflammatory cytokine with a significant cardiodepressant effect. One of the proposed mechanisms for TNF-alpha-induced cardiac contractile dysfunction is increased NO production via iNOS mRNA upregulation, but the role of NO in TNF-alpha-induced myocardial dysfunction is highly controversial. METHODS: Isolated rat hearts studied by a modified Langendorff model were randomly divided into subgroups to investigate the effect of 1-h global cardioplegic ischemia or the effect of 1-h perfusion with exogenous TNF-alpha on the expression of eNOS mRNA and iNOS mRNA and on NO production. RESULTS: After 1 h of ischemia, there were significant increases in TNF levels in the effluent (from hearts), and eNOS mRNA expression had declined (from 0.91 +/- 0.08 to 0.68 +/- 0.19, p < 0.001); but there were no changes in iNOS mRNA expression, and NO was below detectable levels. Perfusion of isolated hearts with TNF-alpha had a cardiodepressant effect and decreased eNOS mRNA expression to 0.67 +/- 0.04 (p < 0.002). Inducible nitric oxide synthase mRNA was unchanged, and NO was below detectable levels. CONCLUSIONS: We believe this is the first study to directly show that TNF-alpha does not increase NO synthesis and release but does downregulate eNOS mRNA in the ischemic and nonischemic isolated rat heart.

Use of intraoperative epiaortic ultrasonography to delineate aortic atheroma.

OBJECTIVE: A cerebrovascular accident (CVA) is a devastating complication of coronary artery bypass grafting (CABG) and a major cause for morbidity and mortality. Aortic manipulation, cannulation, and clamping during CABG may lead to release of atheromatous material from the ascending aorta, which may cause a CVA. This study assessed the hypothesis that the use of intraoperative epiaortic ultrasonography (EAUS) would supplement imaging information with that derived from manual aortic palpation and influence the surgical decision-making approach accordingly. METHODS: After undergoing a mid-sternotomy for CABG, 105 patients underwent EAUS with an 8-MHz transducer ordinarily used for conventional transthoracic echocardiography. The surgical strategy was decided on at three stages: preoperatively, after manual aortic palpation, and following EAUS. RESULTS: The preoperative strategy had assigned 105 patients to the "touched aorta" group that was planned for either on-pump or off-pump CABG (OPCAB) with proximal anastomosis to the aorta. Pathologic lesions of the atheromatotic ascending aorta were evident in 40 patients (38%), with the lesions detected in 22 patients (21%) by both palpation and EAUS, and in 18 patients (17%) by EAUS alone. The planned surgical strategy was changed in 29 patients (28%): 25 patients (24%) were converted from on-pump CABG to OPCAB, and the EAUS influenced the choice of the aortic cannulation, cross-clamping, and proximal anastomosis site in 4 patients (4%). Among the changes in surgical decision making, changes in 11 patients (10%) were based on lesion detection by both manual palpation and EAUS; in 18 patients (17%), changes resulted from pathologic evidence provided by EAUS alone. CONCLUSIONS: This study showed EAUS to be more sensitive in detecting atherosclerotic lesions than manual intraoperative palpation of the ascending aorta. This investigation contributes new data on the effect of EAUS on intraoperative surgical approach in the era of OPCAB. The use of EAUS has emerged as an important tool in intraoperative decision making, and we recommend its use routinely in CABG procedures.

Heparin added to cardioplegic solution inhibits tumor necrosis factor-alpha production and attenuates myocardial ischemic-reperfusion injury.

OBJECTIVES: Tumor necrosis factor (TNF)-alpha is known to be a proinflammatory cytokine that has a pronounced negative inotropic effect and plays an important role in ischemic-reperfusion injury. METHODS: Twenty isolated rat hearts were randomly divided equally into two groups (heparin and non-heparin) and were perfused with a Krebs-Henseleit solution using a modified Langendorff model. The influence of heparin on the synthesis and release of TNF-alpha by isolated rat hearts after 1 h of global cardioplegic ischemia and on left ventricular (LV) performances during 30 min of postischemic reperfusion was investigated. RESULTS: Significant mean (+/- SEM) amounts of TNF-alpha in myocardial tissue (1,149 +/- 33.7 pg/g) and effluent (951.8 +/- 27.3 pg/mL) from the coronary sinus were detected after global cardioplegic ischemia. The addition of heparin to the cardioplegic solution significantly improved the recovery of LV function in the postischemic heart (p < 0.0001 for all measurements). TNF-alpha protein production in the heparin-treated hearts was below detectable levels despite a postischemic increase of TNF-alpha messenger RNA expression in both heparin-treated hearts and nontreated hearts (0.71 +/- 0.06 and 0.8 +/- 0.12 relative optical density, respectively). CONCLUSION: This study shows, for the first time, that heparin causes the inhibition of TNF-alpha protein synthesis and release from the isolated ischemic rat heart within the posttranscriptional stage, and that it prevents the depression of LV function caused by ischemic-reperfusion injury.

Thermo-wrap technology preserves normothermia better than routine thermal care in patients undergoing off-pump coronary artery bypass and is associated with lower immune response and lesser myocardial damage.

OBJECTIVE: Perioperative hypothermia might be detrimental to the patient undergoing off-pump coronary artery bypass surgery. We assessed the efficacy of the Allon thermoregulation system (MTRE Advanced Technologies Ltd, Or-Akiva, Israel) compared with that of routine thermal care in maintaining normothermia during and after off-pump coronary artery bypass surgery. METHODS: Patients undergoing off-pump coronary artery bypass surgery were perioperatively and randomly warmed with the 2 techniques (n = 45 per group). Core temperature, hemodynamics, and troponin I, interleukin 6, interleukin 8, and interleukin 10 blood levels were assessed. RESULTS: The mean temperature of the patients in the Allon thermoregulation system group (AT group) was significantly ( P < .005) higher than that of the patients receiving routine thermal care (the RTC group); less than 40% of the latter reached 36 degrees C compared with 100% of the former. The cardiac index was higher and the systemic vascular resistance was lower ( P < .05) by 16% and 25%, respectively, in the individuals in the AT group compared with in the individuals in the RTC group during the 4 postoperative hours. End-of-surgery interleukin 6 levels and 24-hour postoperative troponin I levels were significantly ( P < .01) lower in the patients in the AT group than in the RTC group. The RTC group's troponin levels closely correlated with their interleukin 6 levels at the end of the operation ( R = 0.51, P = .002). CONCLUSIONS: Unlike routine thermal care, the Allon thermoregulation system maintains core normothermia in more than 80% of patients undergoing off-pump coronary artery bypass surgery. Normothermia is associated with better cardiac and vascular conditions, a lower cardiac injury rate, and a lower inflammatory response. The close correlation between the increased interleukin 6 and troponin I levels in the routine thermal care group indicates a potential deleterious effect of lowered temperature on the patient's outcome.

Pharmacological preconditioning with monophosphoryl lipid A improves post ischemic diastolic function and modifies TNF-alpha synthesis.

OBJECTIVE: Pharmacologic preconditioning represents an attractive myocardial protection strategy. Tumor necrosis factor-alpha plays an important role in myocardial ischemia-reperfusion injury. We aimed to determine the effect of Monophosphoryl lipid A-induced delayed preconditioning on diastolic and systolic left ventricular function and tumor necrosis factor-alpha synthesis during ischemia and reperfusion. METHODS: Rats (n=10) were pretreated with Monophosphoryl lipid A (350 microg/kg) or vehicle (n=9). Twenty-four hours later, the hearts were isolated and perfused on a Langendorff apparatus. Hemodynamic measurements, tumor necrosis factor-alpha mRNA expression and protein content were studied after stabilization (baseline), after 35 min of global ischemia and at 40 min of reperfusion. RESULTS: Left ventricular developed pressure and peak rate of left ventricular developed pressure (dP/dt) rise were comparable between the animals in the control and Monophosphoryl lipid A treated groups during baseline but were higher in Monophosphoryl lipid A group at reperfusion (74+/-4 vs 51+/-5 mmHg, 3340+/-172 vs 2240+/-156 mmHg/s, respectively, P<0.01). dP/dt fall was significantly lower in the MLA group (2630+/-225v 1580+/-210 mmHg/s, P<0.01) at 40 min of reperfusion as well as end diastolic pressure. Baseline tumor necrosis factor-alpha mRNA (expressed as arbitrary densitometry units) were higher in the Monophosphoryl lipid A group (1.3+/-0.1 vs 0.5+/-0.03, P<0.05) but remained constant after ischemia and reperfusion (1.3+/-0.1 and 1.4+/-0.03, P=0.2), while further increase was observed in the control group (from 1.0+/-0.1 to 1.4+/-0.1, P<0.05). Tumor necrosis factor-alpha protein content from heart effluent in the control group was increased during reperfusion (79+/-30 and 200+/-22pg/ml, P<0.05) but was undetectable in the Monophosphoryl lipid A group. Marked TNF-alpha immunostaining of left ventricular tissue was observed only in the control group but no TNF-alpha staining was evident in the Monophosphoryl lipid A treated group at 40 min of reperfusion. CONCLUSION: Monophosphoryl lipid A-induced preconditioning renders the heart more tolerant to ischemia-reperfusion in terms of left ventricular diastolic and systolic function, and prevents tumor necrosis factor-alpha production during ischemia, through aborting the translation phase of tumor necrosis factor-alpha synthesis.

Technical aspects of composite arterial grafting with double skeletonized internal thoracic arteries.

BACKGROUND: Complete myocardial revascularization with internal thoracic arteries (ITAs) improves long-term survival and decreases the rate of repeat operations, compared to vein grafts. Adequate length of the graft in coronary artery bypass graft (CABG) surgery is essential for providing complete arterial revascularization. Extra length can be obtained by skeletonization of both ITAs. In cases where the right ITA (RITA) is too short to bridge the distance to the target anastomotic site, it is used as a free graft in "composite" arterial grafting, a surgical technique in which free arterial conduits are proximally anastomosed end-to-side to an intact ITA. OBJECTIVES: To describe alternative surgical procedures adapted to accommodate special anatomic requirements. DESIGN: Retrospective study from April 1996 to April 1999. PATIENTS: One thousand fifty patients underwent CABG surgery using bilateral skeletonized ITAs: 650 patients (482 men and 168 women; mean +/- SD age, 69 +/- 7 years) underwent composite arterial grafting. Two hundred sixteen patients (33.2%) were diabetics, 87 patients (13.4%) had severe left ventricular dysfunction (ejection fraction < 35%), and 27 patients (4.2%) underwent emergency operations. INTERVENTIONS: The RITA was used as a free graft connected to the in situ left ITA (LITA) in 618 patients. A free LITA was attached to in situ RITA in 32 patients, and minicomposite grafts (free distal LITA on the LITA or free distal RITA on the RITA) were constructed in 38 patients. The average number of grafts was 3.2 per patient (range, 2 to 6 grafts per patient). MEASUREMENTS AND RESULTS: Operative mortality was 2.9% (n = 19), and there were 11 sternal wound infections (1.7%). Early recatheterization was performed in 41 symptomatic patients. The patency rate was 95%. The mean follow-up was 25 months (range, 14 to 36 months), and the 3-year survival was 92.5%, with 97% of the surviving patients being angina free. CONCLUSIONS: Planning CABG surgery using bilateral skeletonized ITAs as arterial conduits affords greater choice in grafting approaches, especially when a composite technique is feasible.

Electromechanical impairment of human auricle and rat myocardial strip subjected to exogenous oxidative stress.

OBJECTIVE: Animal myocardial dysfunction induced by remote ischemia-reperfusion (IR) was shown to be partly accomplished via a direct effect of the pro-oxidant xanthine oxidase (XO). This direct remote effect was not tested in humans. We now assessed the performance of human auricles in the presence of solutions containing XO and/or allopurinol and compared them to those of rat myocardial strips. METHODS: Human and rat specimens (n=64) were separately exposed for 2h to Krebs-Henseleit solution that either (1) exited from rat livers that were earlier perfused for 2h (control-human or control-rat), (2) exited from livers that were earlier made ischemic for 2h (IR-human, IR-rat), (3) contained xanthine (X) 3.8 microM + XO 3 mU ml(-1) (X+XO-human, X+XO-rat), or (4) exited from post 2h-ischemic livers and contained 100 microM allopurinol (human or rat IR + allopurinol groups). RESULTS: Unlike the unchanged electromechanical performance in the control and IR+allopurinol auricles and strips, the rates of contraction, maximal force of contraction and working index of either preparation were reduced by 75-98% (P<0.01) when exposed to the IR reperfusate or to the X+XO-enriched Krebs. The basal amplitudes of contraction in these four latter groups increased twofold (P<0.01). XO activity was similarly low in the control and in the IR+allopurinol groups, but four- to 45-fold (P<0.001) higher in the IR and the X+XO groups, both in the rat and human organs. The reduced glutathione was reduced by approximately 50% (P<0.01) in either preparation in the IR and the X+XO groups compared to the control and IR+allopurinol groups. CONCLUSIONS: Remotely and exogenously originated oxidative burst directly induces electromechanical dysfunction and disrupts oxidant/antioxidant balance in human auricles as it does in the rat myocardial strip.

Cardioplegic ischemia or reperfusion: which is a main trigger for tumor necrosis factor production?

BACKGROUND: Tumor necrosis factor alpha (TNF-alpha) is a key cytokine in the pathogenesis of ischemia-reperfusion injury (I/R) that also possesses negative inotropic and direct cardiotoxic effects. We investigated whether myocardial ischemia and/or reperfusion is the trigger for TNF-alpha synthesis and whether TNF-alpha release is time dependent. METHODS: Isolated rat hearts undergoing 30 min of coronary perfusion with modified Krebs-Henseleit solution followed by cardioplegic arrest for 60 min of global cardioplegic normothermic ischemia (GCI) and 30 min of reperfusion using a modified Langendorff model. Myocardial TNF-mRNA expression and TNF-alpha protein levels in effluent from the coronary sinus were measured at baseline and then after 15, 30, and 60 min of GCI and after 10 and 30 min of reperfusion. RESULTS: GCI induced myocardial TNF-alpha mRNA expression and elevation protein TNF-alpha levels in a time-dependent manner after 30 min of ischemia from 78+/-17 pg/ml to 915+/-287 pg/ml after 60 min (p<0.0015). Reperfusion did not cause time-dependent increase of TNF-alpha synthesis and release but was accompanied by progressive decrease of left ventricular (LV) function. There was a correlation between TNF-alpha protein levels and depression of LV function immediately after GCI but not with TNF-alpha protein levels at 30 min of reperfusion. CONCLUSION: This study demonstrated that myocardial ischemia rather than reperfusion is the main trigger for time-dependent TNF-alpha synthesis. Depression of LV function during reperfusion correlated significantly only with TNF-alpha levels at the end of GCI.

The potential advantage of "no-touch" aortic technique in off-pump complete arterial revascularization.

OBJECTIVES: Off-pump coronary artery bypass grafting (OPCAB) and complete arterial revascularization without proximal anastomosis to the aorta may decrease neurological events after open-heart surgery. Few reports exist regarding the combination of OPCAB and complete arterial revascularization exploring the theoretical advantage of avoiding manipulation of the aorta. We review our results in 110 patients who underwent multiple grafts off-pump complete arterial revascularization. METHODS: 110 patients underwent multiple grafts OPCAB complete arterial revascularization, and were compared to 216 patients who underwent traditional multiple grafts on pump CABG. Preoperative renal failure was 12.7% (n=14) as compared to 5.1%, (n=11, p=0.01) in the control group and 33.6% (n=37) of the patients were 75 years or older as compared to 19.0% (n=41, p=0.003) in the control group. RESULTS: The mean number of grafts per patient undergoing multiple OPCAB complete arterial revascularization was 2.3, as compared to 3.11 in the control group (p<0.001). The mortality rate was 2.73% as compared to 1.85% (NS) in the control group. The incidence of CVA was 0% as compared to 2.31% (p=0.17) in the control group. CONCLUSIONS: Complete arterial OPCAB revascularization without manipulation of the aorta in high-risk patients can be performed with short-term similar results to conventional CABG and very low neurological complications.

Tumor necrosis factor as a mediator of cardiac toxicity following snake envenomation.

OBJECTIVE: To investigate the possible role of tumor necrosis factor in mediating cardiotoxicity following venom injection in a rat. DESIGN: A randomized controlled experimental study using a Langendorff isolated heart model. SETTING: Animal laboratory. SUBJECTS: Adult male Wistar rats. INTERVENTIONS: The control group (n = 10) was injected with saline only. Each animal in the experimental groups 1-3 (n = 10 each) was injected with Vipera aspis venom 500 microg/kg intramuscularly. Group 1 animals received no additional substance beforehand, group 2 animals were injected intramuscularly with 250 microg of soluble tumor necrosis factor receptor (sTNF-R p55) 15 mins before the venom injection, and group 3 animals were injected intraperitoneally with 40 microg of anti-tumor necrosis factor 60 mins before the venom injection. MEASUREMENTS AND MAIN RESULTS: Cardiac performances were investigated following envenomation. Cardiac histology and myocardial tumor necrosis factor-RNA concentrations were assessed. Serum tumor necrosis factor concentrations rose and peaked 2 hrs following envenomation. A reduction in peak systolic pressures, maximum and minimum change in pressure over time, time-pressure integral, and coronary flow occurred in the venom-only-injected rats compared with controls, whereas blocking tumor necrosis factor activity prevented the deleterious cardiac effects of the envenomation. No histologic changes or increases in myocardial tumor necrosis factor-RNA concentrations were detected. CONCLUSION: These results strongly suggest that systemic release of tumor necrosis factor mediates cardiac toxicity following Vipera aspis envenomation.