Regulation of endothelial nitric oxide synthase (eNOS) in myocardium subjected to cardioplegic arrest

BACKGROUND

Nitric oxide (NO) production by both coronary endothelial cells and cardiomyocytes is thought to play a significant role in myocardial pathophysiology following ischemia/reperfusion (I/R).

METHODS

In thirteen pigs subjected to 1 hour cardioplegic arrest (CA) on CPB, left ventricular (LV) biopsies were collected prior to CPB (baseline), at 60 min CPA, at 15 and 30 min reperfusion on CPB, and at 120 min post CPB. LV specimens were immunocytochemically stained against phospho-eNOS (Ser1177), phospho-eNOS (Thr495), phosphorylated ERK1/2, and AKT/PKB. Four additional pigs without CA served as controls. Cardiomyocytes were quantitatively investigated using TV densitometry (gray units: U).

RESULTS

After 60 min CA phosphorylation of eNOS (Ser1177) increased significantly and remained elevated until 30 min of reperfusion. In contrast, eNOS (Thr495) phosphorylation remained unchanged during CA and throughout reperfusion. In control animals, eNOS phosphorylation remained unchanged. Akt/PKB activity significantly increased after 60 min CA and decreased thereafter. ERK1/2 activity remained unchanged during ischemia but increased during reperfusion.

CONCLUSIONS

ENOS activation during ischemia occurs through phosphorylation at Ser1177 mediated by Akt/PKB. ERK1/2 does not seem to be involved in myocardial eNOS regulation especially not via phosphorylation at eNOS (Thr495).

Klarzelltumor der Lunge

Clear cell tumors of the lung are rare tumors composed of epithelioid HMB45 positive tumor cells. It has been proposed that clear cell tumors generate from perivascular epithelioid cells which are also found in renal angiomyolipoma. Due to its morphologic epithelioid features with clear cytoplasm the distinction from either primary or metastatic clear cell carcinoma is difficult. Usually clinical investigations do not lead to the final diagnosis so that only subsequent histological examination and immunophenotyping can establish the correct tumor classification. We describe the case of a 52 year old woman who underwent exploratory thoracotomy because of a lung mass in the right lower lobe. In frozen sections a solid trabecular tumor was diagnosed, paraffin histology and immunohistochemistry revealed a clear cell tumor of the lung. The difficulty of the correct diagnosis of the clear cell tumor of the lung in frozen sections is discussed as well as the differential diagnosis.

The effect of preoperative antiplatelet therapy in coronary artery surgery: blood transfusion requirements for patients on cardiopulmonary bypass

INTRODUCTION

Bleeding after heart operations remains a common complication and contributes to morbidity and death. Recent studies have suggested that antiplatelet therapy (APT) may not increase homologous blood requirements in coronary bypass surgery. The purpose of this study was to examine the influence of APT therapy on haemorrhage and transfusion requirements in patients undergoing coronary artery bypass (CABG) on cardiopulmonary bypass (CPB).

MATERIALS AND METHODS

Records from 290 consecutive patients who underwent CABG with CPB were retrospectively reviewed, including 145 patients who received APT within 5 days prior to surgery and 145 control patients (CON). Blood loss was measured up to 24 h. Demographic and clinical patient data were collected until hospital discharge.

RESULTS

Both groups were well matched with respect to demographic and intra-operative data. There was significantly (p < 0.0005) more mediastinal tube drainage at 24 h in the APT group (1123 mL +/- 537 mL) compared to CON patients (874 mL +/- 351 mL). In addition, the APT group received significantly more units of blood (APT: 2.6 +/- 2.5 vs CON: 1.6 +/- 1.8; p < 0.0005), platelet units (APT: 1.2 +/- 1.8 vs CON: 0.2 +/- 0.8; p < 0.0005), and fresh frozen plasma units (APT: 2.0 +/- 2.2 vs CON: 1.3 +/- 2.0; p = 0.01).

CONCLUSION

This study suggests consideration should be given to delaying elective CABG for patients who have received APT treatment until APT is discontinued for at least 5 days.

Requirement for SAPK-JNK signaling in the induction of apoptosis by ribosomal stress in REH lymphoid leukemia cells

The present studies examined performance of SAPK cascades and apoptotic commitment following ribosomal trauma in REH lymphoid leukemia cells. Ribostatic insults included disruption of ribosomal activity by mechanistically dissimilar agents such as blasticidin-S (BCS) (which binds 28S-rRNA to block peptidyl bond formation), kasugamycin (KSM) (which binds 18S-rRNA to prevent translational initiation), and cycloheximide (CHX) (which blocks A-site to P-site translocation of peptidyl-tRNA). Exposure of REH cells to BCS elicited DNA degradation and apoptotic cytolysis. BCS stimulated JNK1/JNK2 and p38, and their shared targets c-Jun and ATF2. Inhibition of JNK1/JNK2 (but not of p38) antagonized blasticidin-induced apoptosis, whereas targeting alternative ribosomal sites with KSM or CHX limited translation, but failed to activate the SAPK cascade or initiate apoptosis. Our findings indicate that interference with 28S-rRNA by BCS initiates apoptosis in REH cells through recruitment of SAPK-JNK signaling. Disparities between the lethal actions of BCS, KSM, and CHX appear to reflect established differences in the subribosomal targets of these agents. We propose that the SAPK cascade comprises an essential mechanism for the transduction of specific lethal stress signals emanating from active ribosomes, and that interference with the 28S-rRNA, rather than the peptidyl transfer center of the large subunit, is critical to apoptotic commitment.

Impact of myocardial protection during coronary bypass surgery on patient outcome

We have recently shown that continuous coronary perfusion with warm blood enriched with the ultra-short acting beta-blocker Esmolol (ES) improves functional and structural myocardial protection during coronary artery surgery as compared with conventional cardioplegia (CP). The purpose of the present study was to compare both myocardial protection techniques in terms of patient outcome. We retrospectively analyzed the charts of 150 consecutive patients subjected to coronary artery surgery using the ES-technique; 150 patients matched for age, gender, preoperative left ventricular function, history of renal failure, and history of neurological symptoms undergoing surgery with conventional CP during the same time period served as control group. There were no significant differences between both groups with respect to perioperative myocardial infarction rate, need for positive inotropic medication, need for mechanical circulatory support, duration of mechanical ventilation, duration of intensive care unit stay, time of mobilization, postoperative renal failure, cardiac arrhythmias, neurological symptoms, infections or in-hospital mortality. ES-patients were less frequently readmitted to the intensive care unit (ES: 3/150; 2.2% [95% confidence interval: 0-4.2%] vs. CP: 13/150; 8.7% [4.2-13.2%]; P=0.010) and total hospital stay was shorter (ES: 12.3+/-4.8 days [95% CI: 11.5-13.0] vs CP: 13.5+/-3.8 [12.9-14.1] days; P=0.0013), thus saving 159 patient days on the normal ward. Procedural costs were less for the ES-technique (US$ 60 per patient) as compared to the cardioplegia technique (US$ 120 per patient). These data suggest that myocardial protection using the ES-technique does not improve clinical outcome in patients subjected to routine coronary artery surgery, but may save costs.