The role of mitochondrial-mediated apoptosis in a myelodysplastic syndrome secondary to congenital deletion of the short arm of chromosome 4

OBJECTIVE: Myelodysplastic syndromes (MDS) are characterized by peripheral cytopenia and ineffective hematopoiesis. In adult-onset MDS and in certain inherited marrow failure syndromes, apoptosis is increased and is mediated mainly through activation of the Fas pathway. It is unclear whether the various myelodysplastic disorders share the same apoptosis pathways. I investigated apoptosis pathways in a patient with refractory cytopenia with ring sideroblasts associated with congenital 4p deletion to determine the mechanism for bone marrow failure. METHODS: Marrow cells and lymphoblast cell lines generated from peripheral blood were analyzed for apoptosis and protein expression by flow cytometry, Western blot, and confocal microscopy, either directly or after gamma irradiation (15 G). Cell viability after treatment with inhibitors of specific apoptosis pathways was also determined. RESULTS: Compared to controls, the patient's marrow and lymphoblastoid cells showed significantly higher apoptosis rates and activation of caspase-3. Investigation of the mitochondrial apoptosis pathway showed a consistent pro-apoptosis profile, namely, upregulation of Bax, Bax-alpha, cytochrome c, and Apaf1, and low bcl-2. Differences between the patient's and the normal cells were further accentuated after irradiation; p53 expression was strikingly higher in the patient only after irradiation. In contrast, Fas and FADD expression on the patient's and the control's cells were comparable. Addition of caspase 3 or caspase 9 inhibitors markedly increased patient cell viablity, but blocking anti-Fas antibody did not. CONCLUSION: The ineffective hematopoiesis in this case is explained by increased apoptosis and is linked to hyperactivation of the mitochondrial cell death machinery and not to the Fas pathway, which might be secondary to an intramitochondrial defect. This information is crucial because the development of anti-apoptotic agents for the treatment of MDS may not be universally efficacious and should target the specific derangement.     

Increased expression of cardiac angiotensin II type 1 (AT(1)) receptors decreases myocardial microvessel density after experimental myocardial infarction

OBJECTIVE: To study the effects of increased levels of myocardial angiotensin II type 1 (AT(1)) receptor on microvascular growth following myocardial infarction (MI). METHODS: MI was created in transgenic rats (TGR) with a cardioselective overexpression of the AT(1) receptor. We used Sprague-Dawley (SD) rats as controls. Some of the rats were treated with the selective AT(1) receptor blocker losartan (Los). Rats were sacrificed after 3 weeks. RESULTS: MI caused left ventricular (LV) hypertrophy and LV dysfunction in both SD and TGR, which was prevented by AT(1) receptor blockade. Furthermore, MI decreased microvessel density in the non-infarcted myocardium (SD MI: 1653+/-37/mm(2), P<0.01 vs. sham-operated controls), however, microvessel density decreased significantly more in TGR with MI (1298+/-33/mm(2), P<0.01 vs. SD MI). AT(1) receptor blockade restored microvessel density (SD MI Los: 2046+/-195/mm(2); TGR MI Los: 1742+/-47/mm(2); P<0.01 vs. untreated). The differences in microvessel density were still present after correction for LV hypertrophy. The increase in microvessel density after AT(1) receptor blockade was not accompanied by increased myocardial vascular endothelial growth factor (VEGF) levels. Microvessel density correlated with parameters of myocardial stretch, such as LV end-diastolic pressure (-0.681, P<0.001) and N-ANP (-0.424, P=0.01). CONCLUSIONS: Microvessel density after MI is decreased when the AT(1) receptor is overexpressed, and this is amenable to AT(1) receptor blockade. This suggests that efficacy of AT(1) receptor blockers post-MI may not only be due to attenuation of LV remodeling, but also to a stimulatory effect on angiogenesis.     

Inhibition of left ventricular fibrosis by tranilast in rats with renovascular hypertension

BACKGROUND: Growth factors such as transforming growth factor-beta (TGF beta) are believed to have an essential role in cardiac fibrosis. Tranilast (N(3,4-dimethoxycinnamoyl) anthranilic acid) attenuates the increased expression of TGF beta mRNA in vitro. OBJECTIVE: To investigate whether tranilast reduces cardiac fibrosis in rats with two-kidney, one-clip (2K1C) renovascular hypertension. In addition, we tested the in-vitro effects of tranilast on cardiac myocytes and non-myocyte cells. METHODS: We analysed hearts from four groups of rats: sham-operated controls; rats with 2K1C renovascular hypertension; rats with 2K1C renovascular hypertension treated for 12 weeks with the angiotensin converting enzyme (ACE) inhibitor, quinapril (6 mg/kg per day); rats with 2K1C renovascular hypertension treated for 12 weeks with tranilast (400 mg/kg per day). RESULTS : Systolic blood pressure was reduced after quinapril treatment. Tranilast did not alter blood pressure (2K1C: 223 +/- 19 mmHg; 2K1C + quinapril: 149 +/- 15 mmHg (P < 0.01 compared with 2K1C); 2K1C + tranilast: 204 +/- 32 mmHg). Left ventricular weight was likewise reduced significantly by quinapril, but not significantly by tranilast (2K1C: 1.52 +/- 0.2 g; 2K1C + quinapril: 1.26 +/- 0.18 g (P < 0.05 compared with 2K1C); 2K1C + tranilast: 1.37 +/- 0.27 g). Using a computer-aided image analysis system, we demonstrated that tranilast prevented cardiac fibrosis in a blood-pressure-independent manner (P < 0.01 compared with 2K1C). Determination of the cardiac hydroxyproline content similarly revealed a significant reduction in cardiac fibrosis by tranilast (2K1C: 4.92 +/- 0.48 mg/mg; 2K1C + tranilast: 3.97 +/- 0.46 mg/mg; P < 0.05). The effect of tranilast on cardiac fibrosis was comparable to the effects of a blood-pressure-decreasing dose of the ACE inhibitor, quinapril. Cell culture experiments revealed that tranilast significantly decreased the proliferation of cardiac non-myocyte cells. Proliferation of cardiac myocytes was not altered. CONCLUSION: This study revealed that long-term treatment with tranilast markedly attenuated left ventricular fibrosis in rats with renovascular hypertension. This was most probably the result of an antiproliferative effect of tranilast on cardiac non-myocyte cells. Tranilast thus offers a unique new therapeutic approach to the reduction of TGF beta-mediated cardiac fibrosis in vivo.     

Comparison of parecoxib and proparacetamol in endoscopic nasal surgery patients

PURPOSE: The aim of the study was to compare the efficacy of parecoxib for postoperative analgesia after endoscopic turbinate and sinus surgery with the prodrug of acetaminophen, proparacetamol. MATERIALS AND METHODS: Fifty American Society of Anesthesiology (ASA) physical status I-II patients, receiving functional endoscopic sinus surgery (FESS) and endoscopic turbinectomy, were investigated in a prospective, randomized, double-blind manner. After local infiltration with 1% mepivacaine, patients were randomly allocated to receive intravenous (i.v.) administration of either 40 mg of parecoxib (n=25) or 2 g of proparacetamol (n=25) 15 min before discontinuation of total i.v. anaesthesia with propofol and remifentanil. A blinded observer recorded the incidence and severity of pain at admission to the post anaesthesia care unit (PACU) at 10, 20, and 30 min after PACU admission, and every 1 h thereafter for the first 6 postoperative h. RESULTS: The area under the curve of VAS (AUC(VAS)) calculated during the study period was 669 (28-1901) cm x min in the proparacetamol group and 635 (26-1413) cm x min in the parecoxib group (p=0.34). Rescue morphine analgesia was required by 14 patients (56%) in the proparacetamol group and 12 patients (48%) in the parecoxib (p >or= 0.05), while mean morphine consumption was 5-3.5mg and 5-2.0 mg in the proparacetamol groups and parecoxib, respectively (p >or= 0.05). No differences in the incidence of side effects were recorded between the 2 groups. Patient satisfaction was similarly high in both groups, and all patients were uneventfully discharged 24 h after surgery. CONCLUSION: In patients undergoing endoscopic nasal surgery, prior infiltration with local anaesthetics, parecoxib administered before discontinuing general anaesthetic, is not superior to proparacetamol in treating early postoperative pain.