Prostaglandin I2 induces apoptosis via upregulation of Fas ligand in pulmonary artery smooth muscle cells from patients with idiopathic pulmonary arterial hypertension.

BACKGROUND: Pulmonary vascular remodeling with idiopathic pulmonary arterial hypertension (IPAH) is associated with impaired apoptosis of pulmonary artery smooth muscle cells (PASMCs). We have reported that high-dose prostaglandin I2 (PGI2) therapy markedly improved hemodynamics in IPAH patients. The therapy is thought to reverse vascular remodeling, though the mechanism is unclear. The aim of this study is to assess proapoptotic effects of PGI2 on PASMCs obtained from IPAH patients. METHODS: We investigated proapoptotic effects of PGI2 in PAH-PASMCs by TUNEL assays, caspase-3,-7 assays and transmission electron microscopy. We examined the expression of Fas ligand (FasL), an apoptosis-inducing member of the TNF cytokine family, in PAH-PASMCs. We measured the serum FasL levels in IPAH patients treated with PGI2. RESULTS: TUNEL-positive, caspase-3, 7-active cells and fragmentation of the nucleus were detected in PAH-PASMCs treated with PGI2. The percentage of apoptotic cells induced by PGI2 at a high concentration was higher than that induced by PGI2 at a low concentration. PCR-array analysis revealed that PGI2 upregulated the FasL gene in PAH-PASMCs, and we measured the FasL expression by quantitative RT-PCR and Western blotting. PGI2 significantly increased the mRNA level of FasL by 3.98 fold and the protein level of FasL by 1.70 fold. An IP receptor antagonist inhibited the induction of apoptosis, elevation of cyclic AMP and upregulation of FasL by PGI2. Serum FasL level had a significant positive correlation with PGI2 dose in IPAH patients treated with PGI2. CONCLUSIONS: PGI2 has proapoptotic effects on PAH-PASMCs via the IP receptor and upregulation of FasL.

Ultrasound inflammation imaging in rats with myocardial ischemia-reperfusion: evaluation by non-specific targeted contrast microbubbles.

BACKGROUND: Reports on ultrasound inflammation imaging with non-specific targeted microbubbles in the heart have been scarce. We investigated whether inflammation induced by myocardial ischemia-reperfusion in rats could be evaluated by ultrasound inflammation imaging with non-specific targeted microbubbles. METHODS: Six rats subjected to 30 min of occlusion of the left anterior descending artery (LAD) followed by 4 h of reperfusion (ischemia group) and 4 rats subjected to the sham operation (sham group) were used. Ultrasound inflammation imaging was performed 4 h after reperfusion, and non-circulating signal intensity (SI), which reflects the signal derived from microbubbles phagocytosed by neutrophils in inflamed tissue, was calculated by the SI difference between the initial and subsequent imaging both in the LAD and non-LAD areas. The accumulation of neutrophils was confirmed by myeloperoxidase (MPO) staining. RESULTS: Non-circulating SI in the LAD area was significantly greater for the ischemia group than the sham group [5.19 ± 2.19 (ischemia) vs. 0.31 ± 0.13 (sham) dB, p < 0.01]. Non-circulating SI in the LAD area was significantly higher than that in the non-LAD area when compared in the same rat of the ischemia group [5.19 ± 2.19 (LAD) vs. 0.18 ± 0.64 (non-LAD) dB, p < 0.01]. MPO-positive cells were confirmed in the LAD area of the ischemia group. CONCLUSION: Inflammation induced by myocardial ischemia-reperfusion in rats could be quantitatively assessed by ultrasound inflammation imaging with non-specific targeted microbubbles.

Dobutamine stress echocardiography unmasks acute worsening of mitral regurgitation with latent left ventricular outflow tract obstruction behind diastolic heart failure in hypertensive heart disease.

In a 57-year-old woman who was referred as refractory diastolic heart failure, dobutamine stress echocardiography facilitated the diagnosis of acute worsening of mitral regurgitation accompanied with latent left ventricular outflow tract obstruction as a cause of recurrent flash pulmonary edema. Echocardiography revealed the presence of sigmoid septum and concentric left ventricular hypertrophy, being consistent with hypertensive heart disease. Dobutamine induced systolic anterior motion of the mitral valve (SAM) with massive mitral regurgitation, resulting in sudden hypotension with dyspnea. The class Ia antiarrhythmic drug, cibenzoline, reduced the SAM during a dobutamine stress test, followed by no recurrence of flash pulmonary edema.

Evaluation of transmural distribution of viable muscle by myocardial strain profile and dobutamine stress echocardiography.

Transmural distribution of viable myocardium in the ischemic myocardium has not been quantified and fully elucidated. To address this issue, we evaluated transmural myocardial strain profile (TMSP) in dogs with myocardial infarction using a newly developed tissue strain imaging. TMSP was obtained from the posterior wall at the epicardial left ventricular short-axis view in 13 anesthetized open-chest dogs. After control measurements, the left circumflex coronary artery was occluded for 90 min to induce subendocardial infarction (SMI). Subsequently, latex microbeads (90 microm) were injected in the same artery to create transmural infarction (TMI). In each stage, measurements were done before and after dobutamine challenge (10 microg.kg(-1).min(-1) for 10 min) to estimate transmural myocardial viability. Strain in the subendocardium in the control stage increased by dobutamine (from 53.6 +/- 17.1 to 73.3 +/- 21.8%, P < 0.001), whereas that in SMI and TMI stages was almost zero at baseline and did not increase significantly by dobutamine [from 0.8 +/- 8.8 to 1.3 +/- 7.0%, P = not significant (NS) for SMI, from -3.9 +/- 5.6 to -1.9 +/- 6.0%, P = NS for TMI]. Strain in the subepicardium increased by dobutamine in the control stage (from 23.9 +/- 6.1 to 26.3 +/- 6.4%, P < 0.05) and in the SMI stage (from 12.4 +/- 7.3 to 27.1 +/- 8.8%, P < 0.005), whereas that in the TMI stage did not change (from -1.0 +/- 7.8 to -0.7 +/- 8.3%, P = NS). In SMI, the subendocardial contraction was lost, but the subepicardium showed a significant increase in contraction with dobutamine. However, in TMI, even the subepicardial increase was not seen. Assessment of transmural strain profile using tissue strain imaging was a new and useful method to estimate transmural distribution of the viable myocardium in myocardial infarction.

Relationship between renal artery stenosis and intrarenal damage in autopsy subjects with stroke.

BACKGROUND: In patients with cardiovascular disease (CVD), renal dysfunction is a risk factor for the prognosis, but substantial evidence is still lacking about the relationship between clinical characteristics and renal histology. The aim of our study was to evaluate the relationship between the extent of renal parenchymal damage, renal artery stenosis (RAS) and clinical characteristics in autopsy subjects with stroke. METHODS: During the 17-year period 1980-1997, 2167 subjects were autopsied at the National Cardiovascular Center. We studied retrospectively all the autopsy cases aged 40 years and older who had a history of stroke. Thus, 346 subjects remained and they were classified into two groups. Thirty-six subjects had RAS (group A). Three hundred and ten subjects had no RAS, and we randomly chose 102 subjects among them (group B). We evaluated renal parenchymal damage using a semi-quantitative chronic damage score. RESULTS: The average overall chronic damage score was significantly higher in the stenosed kidneys of group A than in the non-stenosed kidneys of group B (9.0+/-2.6 vs 7.0+/-2.7). The contralateral kidneys of group A had a tendency to have milder renal damage than stenosed kidneys. Furthermore, the total score was higher in the subjects with hypertension, diabetes mellitus, proteinuria, renal insufficiency and CVD than in the subjects without such complications. The total score had a significant association with RAS, proteinuria, renal insufficiency, CVD and weight of the kidney. CONCLUSIONS: In autopsy subjects with stroke, we demonstrated that co-existing renal parenchymal damage was more severe in the subjects with RAS, hypertension, diabetes mellitus, proteinuria and renal insufficiency than those without such complications. The presence of RAS, impaired renal function and proteinuria was closely correlated with the severity of renal parenchymal damage.

Embolization of experimental aneurysms using a heparin-loaded stent graft with micropores.

PURPOSE: For percutaneous transluminal angioplasty (PTA), a heparin-loaded stent graft, composed of a commercially available metallic stent with a microporous and surface-modified thin film, has been developed. Early controlled endothelialization is promoted by a regular array of micropores produced by an excimer laser ablation technique. Early thrombus is prevented by a drug delivery system established by impregnation of photoreactive gelatin with heparin. Our stent grafts were used for embolization of experimental carotid aneurysms with an autologous external jugular vein patch in dogs. MATERIALS AND METHODS: At 1 month after formation, the aneurysms were occluded with stent grafts. Affected arteries were removed with the aneurysms, immediately (two aneurysms in one dog), 1 week (four aneurysms in two dogs), 1 month (three aneurysms in two dogs) and 3 months (four aneurysms in two dogs) after embolization, and were studied histologically to evaluate patency and endothelialization over the intraluminal surface of the thin film. RESULTS: Treated carotid arteries were all patent with occluded aneurysms completely at any periods. Even at 1 week after embolization, endothelialization was confirmed on the surface of the stent graft on the lumen side. At 1 and 3 months, all treated aneurysms with enough patent parent arteries were filled with organized tissues and completely occluded. CONCLUSION: Our developed stent graft appears to be promising for the treatment of aneurysms, especially with respect to immediate termination of blood inflow and early endothelialization in the neck of the aneurysm.

Fabrication of micropored elastomeric film-covered stents and acute-phase performances.

To prevent thrombus formation in the acute phase and restenosis in the subacute to chronic phase after stenting of atherosclerotic arteries, we developed a covered stent with a micropored elastomeric film, the blood-contacting surface of which was coated with a photocured gelatin layer immobilized with heparin. Segmented polyurethane (SPU) film (30 microm in wall thickness) as a cover material was multiply micropored by excimer laser-directed microprocessing (pore diameter, 30 microm; interpore distance, 125 microm). An aqueous mixed solution of benzophenone-derivatized gelatin and heparin was coated on the micropored SPU film. Upon ultraviolet light irradiation, a thin layer of a gelatin gel immobilized with heparin was formed and simultaneously fixed on the SPU film. The fully covered stents were assembled by wrapping a balloon-expandable stent with gelatin/heparin gel-layered SPU film and subsequently suturing and then gluing. To assess the validity of this covered stent in vivo, "half-covered" stents, in which half at the distal side was covered with the gel-layered SPU film, was implanted in rabbit common carotid arteries (about 3 mm in diameter). After 3 months of implantation, all the half-covered stents (n = 7) were patent. Regardless of the covered or noncovered region of the stents, the entire luminal surface of the stents was fully endothelialized and a thin neointimal tissue was formed. The potential advantages of a covered stent as designed above are discussed.