Effects of phenylalanine and phenylpyruvate on ATP-ADP hydrolysis by rat blood serum.

The nucleotide (ATP-ADP)/nucleoside (adenosine) ratio in the circulation can modulate the processes of vasoconstriction, vasodilatation and platelet aggregation. The main objective of the present study with rat blood serum was to evaluate the possibility of changes in nucleotide hydrolysis by phenylalanine (Phe) and phenylpyruvate (PP), the levels of which could increase in the circulation of individuals with phenylketonuria. Results demonstrated that Phe in the range 1.0-5.0 mM inhibited the ADP hydrolysis by rat serum. The effect of inhibition by Phe on ATP hydrolysis appeared only at a concentration of 5.0 mM. PP had no significant effect upon nucleotide hydrolysis. Kinetic analysis indicated that the inhibition of ADP and ATP hydrolysis by Phe in rat blood serum is uncompetitive. Conversely, Phe and PP did not affect the hydrolysis of p-nitrophenyl-5'-TMP by rat serum.

Phenylalanine and phenylpyruvate inhibit ATP diphosphohydrolase from rat brain cortex.

The main objective of the present study was to characterize the inhibition by phenylalanine and phenylpyruvate of ATP diphosphohydrolase activity in synaptosomes from the brain cortex of rats. This enzyme participates together with a 5'-nucleotidase in adenosine formation from the neurotransmitter, ATP, in the synaptic cleft. The inhibition of ATP diphosphohydrolase was competitive for nucleotide hydrolysis but 5'-nucleotidase was not affected by these metabolites. Furthermore, the two substances inhibited enzyme activity by acting at the same binding site. If the enzyme inhibition observed in vitro also occurs in the brain of PKU patients, it may promote an increase in ATP levels in the synaptic cleft. In this case, the neurotoxicity of ATP could possibly be one of the mechanisms leading to the characteristic brain damage of phenylketonuria.

Cutting balloon angioplasty for intrastent restenosis treatment.

We describe here two patients with angiographic diagnosis of intrastent restenosis and regional myocardial ischemia. One stent restenosis was located in a native coronary artery and the other in a vein graft. Both were treated with cutting balloon angioplasty (CBA), inflated at low pressures. Angiographic success was obtained and both patients were discharged in the day after the procedure. Cutting balloon angioplasty using low inflation pressures achieved important luminal gains, in these two cases of intrastent restenosis. Further studies are necessary before the effectiveness of this procedure can be precisely defined.

[Coronary arteriography with a very low profile catheter: efficacy and safety of the procedure and of the 60 minute hospital discharge]. / Arteriografia coronária com cateter de muito baixo perfil. Eficácia e segurança do procedimento e da alta hospitalar aos 60 minutos.

PURPOSE: To evaluate the feasibility, efficacy and safety of the use of 4F Judkins catheters for coronary angiography. METHODS: From August/95 to January/96, 70 patients with suspected coronary artery disease underwent coronary cineangiography by the Judkins technique, with 4F catheters. Following puncture of the right femoral artery, 4F sheaths were introduced. At the end of the procedure, the sheath was removed and manual compression was applied for 15 min. Patients were oriented to walk under specialized supervision, 60 min after the procedure, and discharged after 4h. RESULTS: Thirty nine (56%) patients were male, the age ranged from 31 to 83 (mean 57) years and weight from 43 to 101 (mean 69) kg. Optimal quality images were obtained in 62 patients (88%). It was necessary to use larger caliber catheters (6 and 8F) in 8 patients, due to femoral tortuosity or inadequate opacification of coronary arteries. There were no vascular complications nor major bleedings. In only 2 cases (3%) there was a minor bleeding, treated by new local compression. Sixty (85%) patients walked after 60 +/- 5 min and were discharged after 4h. CONCLUSION: The use of 4F catheters for coronary angiography by femoral approach allowed early deambulation with no major bleeding. Image quality was good, with little contrast used and short hospital stay. This technique may lead to a simpler less traumatic and less invasive coronary angiography.

Arteriografia coronária com cateter de muito baixo perfil. Eficácia e segurança do procedimento e da alta hospitalar aos 60 minutos / Coronary arteriography with a very low profile catheter. Efficacy and safety of the procedure and of the 60 minute hospital

OBJETIVO - Avaliar a eficiência, a segurança e a praticidade de angiografia coronária com cateteres 4 French (F), pela técnica de Judkins. MÉtodos - De agosto/95 a janeiro/96, 70 pacientes com suspeita de insuficiência coronária submeteram-se à cinecoronariografia, utilizando introdutores e cateteres 4F. Após o exame, realizava-se compressäo local por 15 min e , 6§ min após, os pacientes eram orientados a caminhar, sob vigilância, sendo dada a alta hospitalar após 4h. RESULTADOS - A idade variou de 31 a 83 (m=57) anos, sendo 39 (56 por cento) homens, com peso entre 43 a 101 (m=69) kg. Obteve-se ótima qualidade de imagem em 62 casos (88 por cento), havendo a necessidade de substituiçäo por cateteres de maior calibre (6 a 8F) em 8 (12 por cento) pacientes. Näo ocorreram complicaçöes vasculares ou sangramentos maiores. Em apenas 2 (3 por cento) casos, houve discreto sangramento, resolvido com nova compressäo local. Sessenta pacientes (85 por cento) deambularam aos 60ñ5 min e tiveram alta hospitalar com 4h, em média