Study of damage in ion-irradiated α-SiC by optical spectroscopy.

UV-visible absorption and Raman scattering spectroscopy were used to investigate the effects of 4 MeV Xe-ion and 4 MeV Au-ion irradiations on α-SiC single crystals. The evolution of transmission spectra upon irradiation evidences an increase of the optical absorption. The optical band-gap energy decreases versus fluence, which is linked to band-gap closure attributed to the creation of localized states into the forbidden energy band. A strong effect of the irradiation temperature is observed as a result of dynamic annealing enhanced by the temperature increase. The Urbach energy increases versus fluence due to disorder accumulation in the damaged layer. Comparison of Urbach energy and disorder parameters extracted from Raman spectra shows that the Urbach energy is sensitive to the disorder induced by the accumulation of point defects.

Early plus delayed hirudin reduces restenosis in the atherosclerotic rabbit more than early administration alone: potential implications for dosing of antithrombin agents.

BACKGROUND: A 2-hour infusion of r-hirudin at the time of balloon angioplasty limits restenosis in atherosclerotic rabbits. Because thrombin activity in the vessel wall after angioplasty remains high for 48 to 72 hours, we hypothesized that a second infusion of hirudin at 24 hours would reduce restenosis more than early treatment alone. METHODS AND RESULTS: Femoral atherosclerosis was induced in 35 rabbits by air desiccation injury and a high-cholesterol diet. At the time of angioplasty, rabbits were randomly assigned to 1 of 4 groups: controls: heparin bolus, saline infusion at 24 hours; early hirudin: hirudin bolus+2 hours' infusion, saline infusion at 24 hours; delayed hirudin: heparin bolus, hirudin infusion+/-bolus at 24 hours; and early+delayed hirudin: hirudin bolus+2 hours' infusion, hirudin infusion+/-bolus at 24 hours. Rabbits were euthanized after 28 days. The early+delayed hirudin treatment group had less loss of minimal lumen diameter by angiography at 28 days. By histomorphometry, cross-sectional area narrowing by plaque was least in the early+delayed treatment group compared with controls (P=0.0001), early hirudin (P=0.01), or delayed hirudin (P=0.001). The early+delayed hirudin group also had a significant reduction in absolute plaque area and an improvement in lumen area compared with the other groups. No differences were observed between treatment groups with respect to the cross-sectional area encompassed by the internal or external elastic laminae. CONCLUSIONS: Combined early+delayed administration of hirudin significantly reduces angiographic restenosis and cross-sectional area narrowing by plaque compared with early or late treatment alone. These results suggest that restenosis after balloon angioplasty is markedly influenced by thrombin-mediated events not only occurring early but also extending beyond the first 24 hours in this model.

Disfunção sistólica aguda de ventrículo esquerdo após drenagem de derrame pericárdico / Transient left ventricular systolic dysfunction after pericardial effusion drainage

Paciente com timoma e função sistólica normal do ventrículo esquerdo desenvolveu tamponamento cardíaco, revertido por pericardiocentese. Após quatro dias, foi submetida à exérese do tumor e, em aproximandamente uma semana da drenagem, apresentou disfunção sistólica aguda e grave do ventrículo esquerdo, que melhorou com terapia venosa, normalizando o quadro em três dias.

[Acute left ventricular systolic dysfunction after pericardial effusion drainage]. / Disfunção sistólica aguda de ventrículo esquerdo após drenagem de derrame pericárdico.

A patient with a thymoma and initially normal ventricular systolic function developed cardiac tamponade, which was relieved by pericardiocentesis. After four days, the tumor was removed and, one week after the relief of tamponade, she developed severe left ventricular systolic dysfunction, that recovered in three days with venous therapy.

Effectiveness of hirulog in reducing restenosis after balloon angioplasty of atherosclerotic femoral arteries in rabbits.

BACKGROUND: Thrombin may play an important role in restenosis after balloon angioplasty (BA). Angiographic and pathologic restenosis have been shown to be reduced after BA in an atherosclerotic rabbit model using recombinant desulfatohirudin, a selective and direct thrombin inhibitor. We hypothesized that potent and specific thrombin inhibition with the synthetic peptide hirulog given intravenously at the time of angioplasty would reduce restenosis in rabbits, confirming a specific role of thrombin in restenosis. METHODS AND RESULTS: Focal femoral atherosclerosis was induced in 27 rabbits by air desiccation endothelial injury followed by a 2% cholesterol diet for 1 month. Rabbits received either heparin (150 units/kg bolus, n = 14) or hirulog (5 mg/kg bolus followed by 5 mg/kg/h for 2 h, n = 13) at the time of BA (2.5-mm balloon with three 60-second, 10-atm inflations 60 s apart). Angiograms performed before and after BA and before sacrifice were analyzed quantitatively. Rabbits were sacrificed 28 days after BA for quantitative histopathologic analysis. Minimum luminal diameter (mm) did not differ between treatment groups before (1.1 +/- 0.2 vs. 1.2 +/- 0.1 mm) or after (1.5 +/- 0.2 vs. 1.6 +/- 0.1) BA in arteries from heparin-versus hirulog-treated rabbits, respectively. At 28 days, however, minimum luminal diameter was significantly less (1.0 +/- 0.4 vs. 1.5 +/- 0.2, p = 0.0001) and percent stenosis was greater (0.46 +/- 0.25 vs. 0.22 +/- 0.08, p = 0.0002) in arteries from heparin- versus hirulog-treated rabbits, respectively. Similarly, quantitative histopathology showed less cross-sectional area narrowing by plaque in the hirulog group (56 +/- 24 vs. 42 +/- 21%, p = 0.04). CONCLUSION: A 2-hour infusion of hirulog at the time of angioplasty improved late angiographic luminal dimensions and reduced cross-sectional area narrowing by plaque in rabbits compared with heparin controls. Together with previous studies, this confirms a specific role for thrombin in restenosis after angioplasty.

[Surgical myocardial revascularization in young patients]. / Cirurgia de revascularização miocárdica em pacientes jovens.

PURPOSE: To determine early and late results of surgical myocardial revascularization (SMR) in young patients. METHODS: We studied retrospectively 73 patients aging less than 40 years and submitted to SMR between 1975 and 1989. The method used was patient card review and thelephone contact with the patient or his physician. RESULTS: Follow-up was obtained in all cases in a period of 2 to 185 (59.9 +/- 41.0) months. Of the coronary risk factors smoking was the most frequent. One vessel coronary artery disease was observed in 16 (21.9%) patients, 2 and 3 vessel coronary artery disease in 26 (35.6%) and 32 (43.8%) patients respectively. SMR was considered complete in 68 (93.2%) patients. An associated procedure was performed on 10 cases: Left ventricular aneurysm repair in 9 (12.3%) and mitral valve replacement in one (1.4%). Perioperative myocardial infarction occurred in 7 (9.5%) patients and one of them died (operative mortality: 1.4%). During follow-up, 6 (8.3%) patients died with an actuarial survival rate of 89.1% at 15 years. An event free survival rate of 68.3% was observed at 10 years. From 66 survivors, 53 (80.3%) were asymptomatic at late follow-up and 48 (72.7%) patients returned to work. CONCLUSION: Surgical myocardial revascularization in young patients associated with medical treatment, has good early and late results with a high percentage of patients asymptomatic and reemployed at a late follow-up.

Cirurgia de revascularização miocárdica em pacientes jovens / Surgical myocardial revascularization in young patients

Objetivo - avaliar os resultados imediatos e tardios da cirurgia de revascularizaçäo em pacientes jovens. Métodos - foram estudados retrospectivaemnte 73 pacientes com idades inferiores a 40 anos e submetidos a cirurgia de revascularizaçäo miocárdica no período de 1975 a 1989, utilizando-se a revisäo dos prontuários e o contato telefônico com os pacientes e/ou médicos-assitentes. Resultados - todos os pacientes foram acompanhados por um período de 2 a 185 (média 59, 9 +/- 41,0) meses. Dentre os fates de risco, o tabagismo foi o mais frequente (89,0 por cento). Dezesseis (21,9 por cento) pacientes apresentavam lesäo coronariana uniarterial, 26 (35,6 por cento) tinham doença biarterial e 32 (43,8 por cento) apresentavam doença triarterial. A revascularizaçäo foi considerada completa em 93, 2 por cento dos casos, sendo que 12,3 por cento foram também submetidos à aneurismectomia do ventrículo esquerdo. Desenvolveram infarto agudo do miocárdio perioperatório 7 (9,5 por cento) doentes, tendo ocorrido móbito hospitalar (1,3 por cento). Tardiamente, 6 (8,3 por cento) pacientes faleceram perfazendo probabilidade de sobrevida de 89, 1 por cento em 15 anos e probabilidade de sobrevida livre de eventos de 68,3 por cento em 10 anos. Encontram-se assintomáticos 80,3 dos pacientes, sendo que 72,7 por cento retornaram ao trabalho. Conclusäo a cirurgia de revascularizaçäo miocárdica em pacientes jovens, associada ao tratamento clínico, mostrou bons resultados a curto e longo prazo, com lata percentagem de pacints sobreviventes, assintomáticos e reassumindo suas atividades trabalhísticas.

Purpose - To determine early and late results of surgical myocardial revascularization (SMR) in young patients. Methods - We studied retrospectively 73 patients aging less than 40 years and submitted to SMR between 1975 and 1989. The method used was patient card review and thelephone contact with the patient or his physician. Results - Follow-up was obtained in all cases in a period of 2 to 185 (59.9±41.0) months. Of the coronary risk factors smoking was the most frequent. One vessel coronary artery disease was observed in 16 (21.9%) patients, 2 and 3 vessel coronary artery disease in 26 (35.ó%) and 32 (43.8%) patients respectively. SMR was considered complete in 68(93.2%) patients. An associated procedure was performed on 10 cases: Left ventricular aneurysm repair in 9 (12.3%) and mitral valve replacement in one (1.4%). Perioperative myocardial infarction occured in 7 (9.5%) patients and one of them died (operative mortality: 1.4%). During follow-up, 6 (8.3%) patients died with an actuarial survival rate of 89.1 % at 15years. An eventfree survival rate of 68.3% was observed at 10 years. From 66 survivors,53 (80.3%) were asymptomatic at late follow-up and 48 (72.7%) patients returned to work Conclusion - Surgical myocardial revascularization in young patients associated with medical treatment, has good early and late results with a high percentage of patients asymptomatic and reemployed at a late follow-up

Rheological studies of photopolymerized dental composites.

An oscillating rheometer was constructed to study the polymerization of light-cured dental composites. The instrument is based on the forced harmonic oscillator, where the polymerization of the sample leads to a reduction of amplitude of oscillations. The polymerization time as determined for different materials seemed to be influenced by the filler particle size. The results obtained for the viscosity and shear modulus for a class of samples agreed with values published using other instruments and methods.

[Infection of polytetrafluorethylene prosthesis in modified Blalock-Taussig anastomosis]. / Infecção de prótese de politetrafluoretileno em anastomose de Blalock-Taussig modificada.

A 16 month-old baby submitted to systemic-pulmonary shunt with a polytetrafluorethylene prosthesis, who presented hyperthermia, radiologic signs of pulmonary opacifications and positive culture for staphylococcus aureus. Reoperation disclosed a prosthesis pseudoaneurysm, with disconnection of the anastomosis and evidences of infection. This complication has a low diagnostic rate and a high mortality and should always be suspected when signs of systemic infection become apparent in the postoperative period of polytetrafluorethylene systemic-pulmonary shunt.

[Hospital risk factors in subclavian-pulmonary anastomosis with polytetrafluoroethylene graft]. / Fatores de risco hospitalar na anastomose subclávia-pulmonar com enxerto de politetrafluoretileno.

PURPOSE: Identification of risk factors for mortality in subclavian-pulmonary anastomosis using polytetrafluorethylene (PTFE). PATIENT AND METHODS: Immediate surgical results (30 days) were analyzed in 180 cyanotic patients consecutively operated on from september 1979 to march 1989. RESULTS: The hospital mortality was 12.7% (23 patients) and age at surgery, low weight (less than 3 kg) and preoperative diagnosis were considered risk factors for mortality. Pulmonary artery diameter at echocardiography, date of surgery and diameter of the conduits were associated with increased risk, but this association lacked statistical significance. Sex and previous palliative surgery have not increased hospital mortality. CONCLUSION: We believe that identification of risk factors to PTFE conduit implant plays an important role in the preoperative management of those patients in order to obtain better results in this life saving procedure.

Análise comparativa da açäo de instrumentos de acabamento de resina composta / Comparative analysis of the action of finishing tools of composite resins

Ao se depararem com uma quantidade muito grande de instrumentos de acabamento de superfície das resinas compostas, os autores procuraram analisá-los, fazendo uma comparaçäo entre seus efeitos. Ensaiaram pontas diamantadas, discos coarse de Sof-Lex

Aparelho elétrico para polir corpos de prova com lixa-tira / Electric equipment for polishing samples ash sandpapers

Devido às dificuldades encontradas para o polimento homogêneo de corpos de resina composta, com lixa-tira, foi construído um aparelho elétrico (lixadeira) que muito auxiliou nos testes de 12 diferentes tipos de lixas-tiras