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Acidosis activates complement system in vitro.

Abstract

We investigated the in vitro effect of different forms of acidosis (pH 7.0) on the formation of anaphylatoxins C3a and C5a. Metabolic acidosis due to addition of hydrochloric acid (10 micromol/ml blood) or lactic acid (5.5 micromol/ml) to heparin blood (N=12) caused significant activation of C3a and C5a compared to control (both p=0.002). Respiratory acidosis activated C3a (p=0.007) and C5a (p=0.003) compared to normocapnic controls. Making blood samples with lactic acidosis hypocapnic resulted in a median pH of 7.37. In this respiratory compensated metabolic acidosis, C3a and C5a were not increased. These experiments show that acidosis itself and not lactate trigger for activation of complement components C3 and C5.

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BibTeXRIS

M Emeis, J Sonntag, C Willam, E Strauss, M M Walka, M Obladen. 1998. Acidosis activates complement system in vitro.. https://doi.org/10.1080/09629359990649

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Glibenclamide attenuates ischemia-induced acidosis and loss of cardiac function in rats.

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Effects of regional hypoxia and acidosis on Rb(+) uptake and energetics in isolated pig hearts: (87)Rb MRI and (31)P MR spectroscopic study.

The study compared the effects of regional hypoxia and acidosis on Rb(+) uptake and energetics in isolated pig hearts perfused by the Langendorff method. The left anterior descending artery (LAD) was cannulated and the LAD bed was perfused with the same specific flow as the whole heart. Following equilibration with normal Krebs-Henseleit buffer (KHB, pO(2) 568 mm Hg, pH 7.42) the perfusate was switched to one that contained Rb(+) (Rb-KHB). Simultaneously, perfusion through the LAD was carried out with hypoxic (pO(2)=31 mm Hg), an acidemic (pH 7.12) or normal (pO(2)=550 mm Hg) Rb-KHB for 120 min. (87)Rb images of the entire heart or localized (31)P spectra from the left ventricular anterior wall were acquired. Hypoxia decreased the maximal (87)Rb image intensity and Rb(+) flux in the anterior wall to 79+/-9% and 85+/-7%, respectively, of that in the posterior wall. Extracellular acidosis did not affect (87)Rb image intensity and reduced Rb(+) flux (83+/-10%). During hypoxia phosphocreatine and ATP decreased to 36+/-10 and 50+/-15% of baseline, respectively and intracellular pH (pHi) decreased to 6.90+/-0.05. Extracellular acidosis did not affect the phosphocreatine or ATP levels but reduced pHi (7.06+/-0.18 vs. 7.26+/-0.06 in control). We suggest that intracellular acidosis plays a role in the inhibition of Rb(+) uptake during hypoxia.

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Intrapartum fetal stimulation tests: a meta-analysis.

OBJECTIVE: To assess the performance of stimulation tests for the prediction of intrapartum fetal acidemia. DATA SOURCES: We conducted a MEDLINE (Internet Grateful Med) literature review from 1966 to 2000 using the terms "fetal scalp pH," "fetal scalp stimulation," and "fetal acoustic stimulation." STUDY SELECTION: Articles were included if sensitivity, specificity, and predictive values for intrapartum fetal acidemia could be calculated. Reactivity was a fetal heart rate (FHR) acceleration of 15 beats per minute for 15 seconds. Likelihood ratio and 95% confidence intervals (CIs) for four different fetal provocations were calculated using the Cochrane collaboration 2000 Review Manager 4.1. This permitted an estimate of the degree of confidence surrounding the point estimate of the likelihood ratio for the presence or absence of acidemia given a positive or negative test. The likelihood ratio is a stable predictive property of any test because it combines information from both sensitivity and specificity, is independent of prevalence, and avoids the limitations of traditional predictive values. TABULATION, INTEGRATION, AND RESULTS: Eleven of 512 articles met criteria for inclusion and included four stimulation tests - fetal scalp puncture, Allis clamp scalp stimulation, vibroacoustic stimulation, and digital scalp stimulation. Pooled likelihood ratio and 95% CIs were similar among the four different stimulation tests. Each test was very useful at predicting both the lack of and the presence of fetal acidemia. Likelihood ratio and 95% CIs for the prediction of fetal acidemia given a positive test were: scalp puncture 8.54 (CI 1.28, 56.96), Allis clamp 10.4 (CI 1.47, 73.61), vibroacoustic stimulation 5.06 (CI 2.69, 9.50), and digital 15.68 (CI 3.22, 76.24). For a negative test, these were: scalp puncture 0.12 (CI 0.02, 0.78), Allis clamp 0.10 (CI 0.01, 0.68), vibroacoustic stimulation 0.20 (CI 0.11, 0.37), and digital 0.06 (CI 0.01, 0.31). CONCLUSION: Intrapartum stimulation tests appear to be useful to rule out fetal acidemia in the setting of a nonreassuring FHR pattern. Our data reveal the degree of confidence around the estimate of the likelihood ratio of a stimulation test. The very low negative likelihood ratios warrant the use of these tests when a nonreassuring intrapartum FHR pattern appears. Because these tests are less than perfect, caution is advised; careful continued monitoring with repeat testing during the course of labor should be performed as long as suspicious FHR patterns persist. Fetal scalp pH should be determined whenever possible after a positive stimulation test (lack of acceleration).

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