Lipid peroxidation by Pseudomonas aeruginosa in the pathogenesis of nosocomial sepsis.

BACKGROUND: To study whether Pseudomonas aeruginosa may directly trigger peroxidation of polyunsaturated fatty acids, since lipid peroxidation is a mechanism involved in the pathogenesis of sepsis. METHODS: Gamma-linolenic acid (GLA) was administered intravenously at a dose of 25mg/kg in an infusion time of 10 minutes to seven male rabbits. Blood samples were collected from the hepatic veins and from the carotid artery at regular time intervals. One clinical isolate was ex vivo incubated with the serum derived from the latter samples and concentrations of malondialdehyde (MDA) were determined during incubation in the growth medium by the thiobarbiturate assay. RESULTS: Elevated concentrations of MDA compared to their basal levels were found over the first three hours of incubation in the presence of samples collected 30 to 60 minutes after the end of the infusion of GLA. After infusion of GLA concentrations of arachidonic acid in the serum increased to concentrations comparable to those detected in sepsis. CONCLUSION: Direct triggering of lipid peroxidation by nosocomial isolates might be proposed as a pathogenetic mechanism of sepsis.

Leukotrienes and essential fatty acids patterns in children with severe protein energy malnutrition

The objective of this study is to investigate the roles of leukotrienes [LTs] and essential fatty acids [EFA] in the pathophysiology of severe protein energy malnutrition [PEM]. Plasma cysteinyl LTs [LTC[4], LTD[4], LTE[4]] and plasma EFA levels were measured by ELISA and gas liquid chromatography after plasma extraction respectively, in 40 severely malnourished children with kwashiorkor [n=20] and marasmus [n=20]. Ten well nourished children of matching age served as control. The cysteinyl LTs level was significantly higher in kwashiorkor group than in marasmic or control groups [p<0.05]. The plasma fatty acid patterns in malnourished children indicated changes characteristic of EFA deficiency, with lower linoleic acid [LA], alpha-linolenic acid [alpha LNA], arachidonic acid [AA] and docosahexaenoic acid [DHA] levels, accompanied by significantly higher oleic acid levels in both malnourished groups. The lowest values of LA and alpha-LNA were detected in marasmic group and the lowest levels of AA and DHA were in kwashiorkor group [p<0.05]. There was an inverse correlation between AA and LTs levels in children with kwashiorkor. Clinical problems associated with kwashiorkor such as hair and skin changes, edema, psychomotor alteration and hepatomegaly were significantly correlated directly with LTs and in versely with AA levels. The findings of this study suggest that cysteinyl LTs and EFA deficiency are involved in the pathophysiology of PEM particularly kwashiorkor and that severe PEM is associated with impaired FA desaturation and elongation pathways

Acidos grasos poliinsaturados de cadena larga en eritrocitos de prematuros alimentados por vía enteral con leche humana de pretérmino o con una fórmula convencional / Long chain polyunsaturated fatty acids in erythrocytes of preterm babies enterally feed with maternal milk or with a convencional formula

Objetivo: estudiar el efecto de alimentar prematuros sanos con peso adecuado para la edad gestacional (RNPrT-AEG) con una fórmula convencional (FC) que no aporta ácidos grasos poliinsaturados de cadena larga o con leche humana de pretérmino (CMPrT), sobre el contenido de ácidos grasos de cadena larga en los fosfolípidos de sus eritrocitos al tercer día de vida. Método: se comparó la composición porcentual de los ácidos grasos saturados, monoinsaturados y poliinsaturados, de la fracción fosfolípidica de eritrocitos, en RNPrT-AEG en sangre de cordón y al tercer día de vida, después de ser alimentados por vía enteral con FC o CMPrT. Así mismo se compararon los resultados con los obtenidos en recién nacidos de término (RNT) alimentados con leche humana de término (CMT). Resultados: tanto los RNPrT-AEG alimentados con FC como con CMPrT disminuyeron los niveles de ácidos grasos monoinsaturados al tercer día de vida (17,8 y 17,5 vs 19,2 por ciento, respectivamente, p < 0,05). Los RNPrT-AEG alimentados con CMPrT mantuvieron el contenido de ARA y DHA (12,6 y 4 vs 12,1 y 3,6 por ciento respectivamente), en tanto que los alimentados con FC disminuyeron significativamente el ácido araquidónico y docosahexaenoico (11,5 y 3 vs 12,1 y 3,6 por ciento respectivamente, p < 0,05), y todos los ácidos grasos poliinsaturados de cadena larga (mayor igual 20 C; PCL), en sus eritrocitos. Al comparar al tercer día de vida los RNPrT vs RNT alimentados con calostro materno, los eritrocitos de los pretérmino tienen significativamente menos contenido de ARA y DHA (12,6 vs 13; 4 por ciento y 4 vs 4,7 por ciento, respectivamente, p < 0,05). Conclusión: el calostro materno de pretérmino permite mantener mejor el contenido de PCL a los 3 días de vida que la alimentación con una fórmula convencional, sin llegar a los niveles de PCL contenidos en eritrocitos de RNT alimentados con CMT. Los requerimientos nutricionales de los PCL de RNPrT-AEG, que deban alimentarse por vía enteral o parenteral, o que no puedan alimentarse con calostro materno, podrían cubrirse proporcionándoles precozmente fórmulas cuya cantidad y composición lipídica se asemeje a la del calostro de madres con parto prematuro

Physiology and function of platelets from patients with Alzheimer's disease.

The discovery that intact Alzheimer amyloid precursor protein is present in platelet granules, has created a great interest in the biochemistry, physiology and function of platelets of patients with Alzheimer disease (AD). In this study we monitored various biochemical and physiological parameters, such as serotonin and adenine nucleotide levels, membrane fluidity, agonist-mediated release of arachidonic acid, thromboxane formation, calcium mobilization, as well as irreversible aggregation and secretion of granule contents. Platelets of patients with AD responded poorly when stirred with weak or potent agonists on a platelet aggregometer. Although capable of agonist-mediated calcium mobilization and synthesis of thromboxanes, the aggregation response of platelets of patients with AD to thrombin and archidonate was considerably compromised. In view of the normal biochemistry and signal transduction capabilities, the compromised response of these cells to potent agonists like thrombin suggested an extrinsic defect. The present study has shown that a plasmatic factor is at least in part responsible for the functional abnormalities of AD platelets.