Aluminum induces lipid peroxidation and aggregation of human blood platelets.

Aluminum (Al3+) intoxication is thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations arising from long-term hemodialysis. Although the metal does not present redox capacity, it can stimulate tissue lipid peroxidation in animal models. Furthermore, in vitro studies have revealed that the fluoroaluminate complex induces diacylglycerol formation, 43-kDa protein phosphorylation and aggregation. Based on these observations, we postulated that Al(3+) -induced blood platelet aggregation was mediated by lipid peroxidation. Using chemiluminescence (CL) of luminol as an index of total lipid peroxidation capacity, we established a correlation between lipid peroxidation capacity and platelet aggregation. Al3+ (20-100 microM) stimulated CL production by human blood platelets as well as their aggregation. Incubation of the platelets with the antioxidants nor-dihydroguaiaretic acid (NDGA) (100 microM) and n-propyl gallate (NPG) (100 microM), inhibitors of the lipoxygenase pathway, completely prevented CL and platelet aggregation. Acetyl salicylic acid (ASA) (100 microM), an inhibitor of the cyclooxygenase pathway, was a weaker inhibitor of both events. These findings suggest that Al3+ stimulates lipid peroxidation and the lipoxygenase pathway in human blood platelets thereby causing their aggregation.

Determination of serum aluminum, platelet aggregation and lipid peroxidation in hemodialyzed patients.

Aluminum (Al3+) overload is frequently associated with lipid peroxidation and neurological disorders. Aluminum accumulation is also reported to be related to renal impairment, anemia and other clinical complications in hemodialysis patients. The aim of the present study was to determine the degree of lipid peroxidation, platelet aggregation and serum aluminum in patients receiving regular hemodialytic treatment. The level of plasma lipid peroxidation was evaluated on the basis of thiobarbituric acid reactive substances (TBARS). Mean platelet peroxidation in patients undergoing hemodialysis was significantly higher than in normal controls (2.7 +/- 0.03 vs. 1.8 +/- 0.06 nmol/l, P<0.05). Platelet aggregation and serum aluminum levels were determined by a turbidimetric method and atomic absorption spectrophotometry, respectively. Serum aluminum was significantly higher in patients than in normal controls (44.5 +/- 29 vs. 10.8 +/- 2.5 microg/l, P<0.05). Human blood platelets were stimulated with collagen (2.2 microg/ml), adenosine diphosphate (6 microM) and epinephrine (6 microM) and showed reduced function with the three agonists utilized. No correlation between aluminum levels and platelet aggregation or between aluminum and peroxidation was observed in hemodialyzed patients.

Prevalência de resistência a proteína C ativada (RPCA) em pacientes atendidos no Laboratório Médico Santa Luzia / Prevalence of activated protein C resistance (APCR) in patients attended in the medical laboratory Santa Luzia

O avanço no conhecimento dos mecanismos que regulam a hemostasia possibitou a identificação de alterações na coagulação sanguínea que estão na origem dos fenômenos trombóticos. O objetivo deste trabalho foi avaliar a prevalência de RPCA em pacientes atendidos no Laboratório Médico Santa Luzia - Florianópolis, SC. Foram avaliados retrospectivamente 365 pacientes com idade variando de 5 a 81 anos, homens e mulheres com distúrbio trombótico. Os resultados mostraram que 12,9% dos pacientes tinham RPCA positivo, com uma maior prevalência em indivíduos de sexo feminino (68,1%) quando comparados com os do sexo masculino (31,9%).

Effects of catechins on human blood platelet aggregation and lipid peroxidation.

The activity of catechins was studied for inhibitory activity in human blood platelets. Platelet aggregation and peroxidation were evaluated in platelet rich plasma (PRP) obtained from samples of healthy volunteers. Human blood platelets were submitted to stimulation with 300 microM arachidonic acid, 3 microM adenosine diphospate (ADP) and 6 microM epinephrine. Treatment with (200 microg/mL) catechin or epicatechin was sufficient to exhibit a potent inhibitory effect of the three agents. The inhibitory effect was dose dependent at concentrations of 20-200 microg/mL. Using malondialdehyde (MDA) as an index of total lipid peroxidation capacity, decreased production of MDA of the platelets treated with catechin or epicatechin after stimulation by arachidonic acid was observed. These findings suggest that catechins protect platelets from peroxidative stress and their aggregation.

Hemostasia na gravidez: um estudo prospectivo / Hemostasis in pregnancy: a prospective study

A gravidez normal está associada a complexas alterações da hemostasia que resultam em um estado de hipercoagulabilidade sanguínea. O objetivo do presente estudo foi avaliar prospectivamente o perfil da hemostasia em gestantes encaminhadas pelasunidades básicas de saúde de Joinville. Foram avaliados 120 gestantes nos períodos de três trimestres, através dos seguintes parâmetros: determinação do tempo de protrombina (TP), tempo de tromboplastina parcial ativada (TTPa), dosagem de fator VIII, dosagemde fibrinogênio e contagem de plaquetas. A análise dos resultados mostrou uma diminuição significativa entre a média dos três trimestres de gestação em relação ao grupo controle para os tempos de protrombina(TP), tromboplastina parcial ativada( TTPa ) e a contagem de plaquetas. A concentração dos fatores VIII e fibrinogênio aumentaram significativamente a partir do segundo trimestre. Estes resultados permitem concluir que, a gravidez normal está associada a uma exacerbação do mecanismo de coagulação, onde asíntese excederia o consumo.

Triagem laboratorial para a pesquisa de anticoagulante lúpico (AL) em pacientes atendidos no Hospital Universitário de Florianópolis, SC / Laboratory triage for lupic anticoagulant (LA) research in patients attended at Hospital Universitario de Florianopolis, SC

Os anticorpos anticoagulante lúpico (AL) são inibidores adquiridos que reagem contra fosfolípides in vitro, promovendo o prolongamento dos testes de coagulação fosfolípides dependentes. Clinicamente, as complicações tromboembólicas constituem se em manifestações comuns em pacientes portadores de anticorpos antifosfolípides. O presente trabalho teve por objetivo realizar a triagem laboratorial para a pesquisa do anticorpo anticoagulante lúpico em pacientes com trombofilia a esclarecer, atendidos no Hospital Universitário de Santa Catarina. Foram avaliados 238 pacientes do sexo masculino e feminino, de fevereiro abril de 2004. Am¨¦dia de idade foi de 48 anos (variando de 15 a 73 anos). O anticoagulante lúpico (AL) foi detectado por três testes de triagem (tempo de tromboplastina parcial ativada (TTPA), tempo de coagulação do kaolim (KCT) e do veneno de víbora de Russel diluído(dRVVT).A prevalência de AL foi de 7,6% (12 do sexo feminino e 6 do sexo masculino). Das 238 amostras, 15 foram positivas para o KCT, quando as amostras foram testadas para o dRVVT observou-se que 17 amostras apresentaram resultados positivos. No total, 13 amostras apresentaram-se positivas para ambos os testes. De acordo com os resultados, obtidos podemos sugerir que os pacientes estudados apresentam em sua maioria anticorpos direcionados contra a protrombina e/ou alfa2-glicoproteína I.

The lupic anticoagulant antibodies (LA) are acquired inhibitors which may react against phospholipids in vitro promoting the stretching of phospholipids-dependent coagulation tests Clinically, the tromboembolic complications are common manifestations in patients with anti-phospholipids antibodies. This work aims to develop a laboratory triage for the research of lupic anticoagulant antibodies in patients with non-clear cases of trombophilia attended at Hospital Universit¨¢rio de Santa Catarina. A total of 238 patients, males and females, were evaluated in the period comprehended between February and April, 2004. The average age of the patients was 48 years (ranging from 15 to 73 years). Lupic anticoagulant was detected by means of three triage tests (partial active tromboplastine time (KPTT), kaolin coagulation time (KCT) and Dilute Russell¡¯s Viper Venom time (dRVVT). The prevalence of LA was equal to 7.6 % (12 females and 6 males). Fifteen out of 238 samples were tested positive by KCT. The analysis of the samples by dRVVT resulted in 17 positive diagnosis. A total of 13 samples presented positive results in both tests. According to the results obtained, it can be suggested that the patients evaluated presented in the majority of cases anti-bodies directed against protrombine and/or alpha2-glycoprotein I.

Aluminum induces lipid peroxidation and aggregation of human blood platelets

Aluminum (Al3+) intoxication is thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations arising from long-term hemodialysis. Although the metal does not present redox capacity, it can stimulate tissue lipid peroxidation in animal models. Furthermore, in vitro studies have revealed that the fluoroaluminate complex induces diacyglycerol formation, 43-kDa protein phosphorylation and aggregation. Based on these observations, we postulated that Al3+-induced blood platelet aggregation was mediated by lipid peroxidation. Using chemiluminescence (CL) of luminol as an index of total lipid peroxidation capacity, we established a correlation between lipid peroxidation capacity and platelet aggregation. Al3+ (20-100 muM) stimulated CL production by human blood platelets as well as their aggregation. Incubation of the platelets with the antioxidants nor-dihydroguaiaretic acid (NDGA) (100 muM) and n-propyl gallate (NPG) (100 muM), inhibitors of the lipoxygenase pathway, completely prevented CL and platelet aggregation. Acetyl salicylic acid (ASA) (100 muM), an inhibitor of the cyclooxygenase pathway, was a weaker inhibitor of both events. These findings suggest that Al3+ stimulates lipid peroxidation and the lipoxygenase pathway in human blood platelets thereby causing their aggregation.

Determination of serum aluminum, platelet aggregation and lipid peroxidation in hemodialyzed patients

Aluminum (Al3+) overload is frequently associated with lipid peroxidation and neurological disorders. Aluminum accumulation is also reported to be related to renal impairment, anemia and other clinical complications in hemodialysis patients. The aim of the present study was to determine the degree of lipid peroxidation, platelet aggregation and serum aluminum in patients receiving regular hemodialytic treatment. The level of plasma lipid peroxidation was evaluated on the basis of thiobarbituric acid reactive substances (TBARS). Mean platelet peroxidation in patients undergoing hemodialysis was significantly higher than in normal controls (2.7 ± 0.03 vs 1.8 ± 0.06 nmol/l, P<0.05). Platelet aggregation and serum aluminum levels were determined by a turbidimetric method and atomic absorption spectrophotometry, respectively. Serum aluminum was significantly higher in patients than in normal controls (44.5 ± 29 vs 10.8 ± 2.5 æg/l, P<0.05). Human blood platelets were stimulated with collagen (2.2 æg/ml), adenosine diphosphate (6 æM) and epinephrine (6 æM) and showed reduced function with the three agonists utilized. No correlation between aluminum levels and platelet aggregation or between aluminum and peroxidation was observed in hemodialyzed patients

Avaliaçäo plaquetária de doadores de sangue / Assessment of the platelet function of blood donnors

A utilizaçäo de hemoderivados constitui-se atualmente numa modalidade terapêutica de fundamental importância no exercício da medicina. Dentre os diversos hemocomponentes que podem ser utilizados, o concentrado de plaquetas (CP) é de grande utilizaçäo em situaçöes de distúrbios hemorrágicos. O estudo teve por objetivo avaliar perfil laboratorial de doadores de plaquetas na sua fase de triagem e o monitoramento dos CP utilizados para fins terapêuticos. Foram avaliados 120 indivíduos adultos selecionados na triagem. As bolsas de CP obtidas foram divididas em grupos de 30 bolsas, respectivamente 0h, 24hs, 48h e 72h após sua preparaçäo. Na triagem a média de plaquetas foi de 1,76x10 a quinta potência/mm cúbicos. Os testes de agregaçäo com colágeno, ADP e adrenalina demonstraram respectivamente 20, 43 e 40 porcento de doadores hipoagregantes. Nas bolsas de CP foi encontrado um volume médio de 50,9ml com concentraçäo plaquetária inicial de 1,74x10 a sexta potência/mm cúbicos, reduzindo 48 porcento em 24hs. A agregaçäo plaquetária reduziu significativamente por colágeno após 48hs e para ADP e adrenalina em 24hs. O pH inicial das bolsas foi de 7,39 alterando-se significativamente em 24hs porém, mantendo-se dentro dos limites normais. Os resultados obtidos nos permitem inferir que o processo de separaçäo e armazenamento promovem um grau de ativaçäo plaquetária significativos. O estudo também demonstra a necessidade de uma reavaliaçäo para os indicadores laboratoriais necessários a doaçäo de plaquetas objetivando adequar a qualidade deste hemoderivado em benefício da populaçäo