Clinical science
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Comment Randomized Controlled Trial Comparative Study Clinical Trial
Increased cationic amino acid flux through a newly expressed transporter in cells overproducing nitric oxide from patients with septic shock.
Increased production of nitric oxide (NO) is thought to be a factor in the pathogenesis of many human diseases - among them the hypotension that often accompanies sepsis. The supply of the cationic amino acid arginine is known to be rate-limiting for NO production. We hypothesized that cationic amino acid transport might be increased in cells producing excess NO from patients with septic shock. ⋯ The activity of the other major cationic amino acid transporter (y+L) was unchanged. The expression of CAT2 mRNA, which encodes a y+ transporter protein, was also increased in these cells. We suggest that CAT2 might be a therapeutic target to prevent excess NO production in sepsis and possibly other human disease states, while leaving basal production unchanged.
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We hypothesized that cytokine production following delayed in vitro cell stimulation (to reproduce physiological cellular status at baseline) may be related to outcome in patients with septic shock. A total of 20 patients were included in a prospective clinical study, conducted in a medico-surgical intensive care unit in a university hospital. Blood samples were obtained at the onset of septic shock; these were treated to retain the cells, but to wash out autologous plasma (containing potential inflammatory stimuli such as cytokines, bacterial products and drugs) and replace it with foetal calf serum. ⋯ Levels of TNF-alpha, interleukin-1 beta and interleukin-10 were significantly higher (P<0.05) when cell stimulation was delayed for 16 h, indicating a functional down-regulation of cells during septic shock. Moreover, TNF-alpha responses obtained with high-dose lipopolysaccharide were significantly greater in cells from patients who subsequently survived septic shock (n=13; median value 1392 pg/ml; range 592-2048 pg/ml) than in cells from non-survivors (n=7; median value 708 pg/ml; range 520-1344 pg/ml). These observations support the existence of individual differences in the inflammatory response that could influence patient outcome following septic shock.
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Randomized Controlled Trial Clinical Trial
The effect of glutamate infusion on cardiac performance is independent of changes in metabolism in patients undergoing routine coronary artery bypass surgery.
In a double-blind randomized placebo-controlled study, the effects of intravenous glutamate infusion on myocardial haemodynamics and metabolism were studied in 22 patients undergoing routine coronary artery bypass graft (CABG) surgery. Immediately after aortic cross-clamp release, an intravenous infusion of a solution of glutamate (125 mmol x l(-1)) at a rate of 1.5 ml x h(-1) x kg(-1) was given over 1 h to 11 patients (G group). The other 11 patients received a placebo infusion (0.9% NaCl) (P group). ⋯ These data show that an intravenous glutamate infusion after routine CABG surgery significantly improved cardiac haemodynamic performance without direct effects on cardiac substrate metabolism. This suggests that a reduction of the afterload via a peripheral vasodilatory effect is the main mechanism leading to the observed changes in haemodynamics. Earlier claims that patients with post-operative cardiac failure show metabolic benefits from the glutamate infusion do not seem to apply to patients undergoing routine CABG surgery.
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Comparative Study
Comparison of two spatially resolved near-infrared photometers in the detection of tissue oxygen saturation: poor reliability at very low oxygen saturation.
Two spatially resolved oximeters, NIRO-300 and OM-200, were compared with regard to the measurement of oxygen saturation values in two forearm muscle groups at rest and during arterial occlusion in nine healthy volunteers. There was a significant correlation between the muscle oxygen saturation values obtained at rest using the two oximeters (n=33, r(2)=0.43, P<0.0001), whereas these values were significantly different during arterial occlusion. Thus, although there was good agreement between muscle oxygen saturation values measured using the two oximeters, the operating range of the tissue oximeters should be recognized and indicated.
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Randomized Controlled Trial Clinical Trial
Effect of intrathecal fentanyl on oxytocin secretion in pregnant women not in labour.
We studied the effects of spinal intrathecal fentanyl on oxytocin secretion in 20 healthy women prior to an elective caesarean delivery at term under spinal anaesthesia. The women were randomly allocated into two groups with respect to spinal anaesthesia. Group I (n=10) received intrathecal bupivacaine (15 mg) plus fentanyl (25 microgram), and Group II (n=10) received intrathecal bupivacaine (15 mg) alone, prior to caesarean section. ⋯ We found no significant differences in plasma oxytocin concentrations of individual subjects before and after intrathecal injection. In addition, there were no significant differences in plasma oxytocin concentrations between the two groups when pooled samples from the subjects were compared for the pre- and post-intrathecal injection phases. We conclude that the spinal intrathecal administration of fentanyl does not suppress oxytocin secretion in pregnant women who are not in labour at term.