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Biomedical subjects

P Vassiliou

Publications and source records attributed to P Vassiliou.

4 recordsLinked to original sources

Long chain versus medium chain lipids in patients with ARDS: effects on pulmonary haemodynamics and gas exchange.

OBJECTIVE: To compare pulmonary haemodynamic and gas exchange alterations in septic patients with ARDS receiving long-chain triglycerides (LCT) versus medium-chain triglycerides (MCT). DESIGN: Prospective, randomised, clinical study. SETTING: Surgical ICU patients in a University Hospital. PATIENTS: Twenty-one septic patients with ARDS were randomly assigned to receive 50 % of their non-protein caloric requirements as either 20 % LCT (group 1, n = 10) or 20% 1:1 mixture of LCT/MCT (group 2, n = 11). INTERVENTION: Intravenous infusion of LCT and LCT/MCT combinations at a rate of 12 g x h(-1). MEASUREMENTS AND RESULTS: The LCT infusion was associated with an increase of pulmonary venous admixture (Qva/Qt) from 24 % +/- 5 % to 37 % +/- 6 %, an increase of mean pulmonary artery pressure (MPAP) from 25 +/- 5 to 33 +/- 4 mmHg and decrease of PaO2/FIO2 from 240 +/- 30 to 180 +/- 35. LCT/MCT administration was only associated with an elevation of oxygen consumption (VO2) from 329 +/- 14 to 396 +/- 12 ml/ min. During lipid infusion group 1 patients presented higher Qva/Qt (37% +/- 6% vs 25% +/- 4%), MPAP (33 +/- 4 vs 27 +/- 3 mmHg) and VO2 (359 +/- 11 vs 396 +/- 12 ml/min) and lower PaO2/FIO2 (180 +/- 35 vs 235 +/- 30) values compared to group 2. CONCLUSION: In conclusion, we have shown that, in septic patients with respiratory failure, LCT administration was associated with more significant changes of Qva/Qt, MPAP and PaO2/FIO2 compared to infusion of an LCT/MCT 1:1 emulsion. Clinically, these transient alterations might cause serious problems in patients with marginal arterial oxygenation and cardio-respiratory impairment.

Adult

The inhibitory action of oxygen radical scavengers on proteinuria and glomerular heparan sulphate loss in the isolated perfused kidney.

The perfused isolated kidney is a partial ischemic system that is characterised by glomerular proteinuria and release of glomerular heparan sulfate. Metabolic changes associated with the levels of glutathione, xanthine oxidase and glyceraldehyde 3-dehydrogenase indicated that oxygen radical metabolites were being produced during the perfusion. We have demonstrated that a mixture of oxygen metabolite scavengers containing mannitol, superoxide dismutase and catalase included in the perfusion medium significantly reduced protein excretion. Similar results were obtained with the administration of allopurinol to the rat 24h prior to kidney removal and allopurinol in the perfusion medium. [35S]Heparan sulfate loss from the glomerulus was totally inhibited by the scavenger mixture. These results suggest that reactive oxygen metabolites may be involved in damage to renal capillaries, specifically to heparan sulfate proteoglycan, which leads to proteinuria as a result of partial ischemia produced during perfusion.

Animals

Partial ischemia and proteinuria during isolated kidney perfusion is accompanied by the release of vascular [35S]heparan sulfate.

The isolated kidney perfused with modified Krebs-Henseleit buffer with amino acids yields heavy proteinuria associated with reduced ATP levels characteristic of partial ischemia. These conditions are associated with a similar perfusion time dependent release of degraded vascular [35S]heparan sulfate proteoglycan into the perfusate solution which included a 60% loss of [35S]macromolecular material from the glomerulus after 2h of perfusion. Small amounts of [35S]macromolecular material were found in the urine and lymph. These results demonstrate that partial ischemia promotes a specific response in the overall renal vasculature, probably involving oxygen reactive metabolites, that results in the preferential release of heparan sulphate from the basement membrane and endothelial cells on the luminal side of the capillary wall.

Adenosine Triphosphate