PubMed · 6576027
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1983. Keyes' method.. https://pubmed.ncbi.nlm.nih.gov/6576027/
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OBJECTIVE: Our purpose was to compare lactate levels with acid-base balance in the umbilical artery with respect to the prediction of pregnancy outcome. STUDY DESIGN: A prospective study of 4045 cord samples was performed. Lactate was measured with a new method that requires 5 microliters of blood and provides the result within 1 minute. RESULTS: The umbilical artery lactate concentrations were significantly elevated in instrumental deliveries (2.65 +/- 1.2 mmol/L) and in emergency cesarean sections (2.44 +/- 1.7 mmol/L) compared with spontaneous vaginal delivery (1.87 +/- 0.94 mmol/L) (p < 0.001, p < 0.001). Lactate correlated significantly to fetal pH, hemoglobin, base deficit, PCO2, and HCO3-. Lactate was comparable to pH and base deficit in sensitivity, specificity, and positive and negative predictive values in relation to morbidity and mortality. CONCLUSION: Umbilical artery lactate concentration and acid-base balance predicted perinatal outcomes with similar efficacies; however, its simplicity makes lactate analysis an interesting alternative in obstetric care.
At present, lactate is the most commonly used buffer in peritoneal dialysis fluids (PDFs). The high lactate concentration in combination with low original pH was demonstrated to suppress phagocytic function. We evaluated the in vitro effects of a newly formulated bicarbonate-buffered PDF containing glycylglycine (BiGG15 and BiGG40; Pierre Fabre Medicament, Castres, France) on peritoneal macrophage (PMO) function, and compared them with those of equiosmolar lactate-buffered PDF (1.5% and 4.25% glucose; pH 5.4 and pH 7.4) and control buffer. Peritoneal macrophages were isolated from the effluents of 10 continuous ambulatory peritoneal dialysis patients and tested for luminol- and lucigenin-enhanced chemiluminescence, superoxide (O2-) generation measured by cytochrome c reduction, killing capacity, and phagocytosis after incubation in the PDF used. Exposure of PMO to lactate-buffered PDF with an original pH of 5.4 resulted in a significant suppression of all PMO functions measured, compared with bicarbonate- and lactate-buffered PDFs with a pH of 7.4. At physiological pH (7.4), chemiluminescence generation of PMO exposed to BiGG15/40 was significantly higher compared with the corresponding equiosmolar lactate-buffered PDF (1,992 +/- 858 x 10(3) cpm/10(4) cells v 856 +/- 398 x 10(3) cpm/10(4) cells; P < 0.004). O2- generation, killing capacity, and phagocytosis were not significantly different after PMO exposure to bicarbonate compared with exposure to lactate-buffered PDF with a neutral pH. Irrespective of the buffer used, high-osmolality PDFs suppressed PMO function significantly more than low-osmolar PDFs. In conclusion, bicarbonate-buffered PDFs are less detrimental to PMO function than lactate-containing PDFs; these preliminary in vitro results need to be confirmed in vivo.
A rigorous mathematical model is developed to describe the distribution of respiration-generated oxidants among reactive sites within the phagolysosomes of leukocytic cells. Reaction parameters include the diffusion coefficient of the oxidant, the intrinsic rate constants for its reaction with the phagosomal membrane and the cell envelopes of entrapped bacteria, the overall rate constant for its reaction with solution components of the phagosomal fluid, and the phagosomal dimensions. The model is used to describe the dynamics of randomly generated .OH and HCO3. radicals within the phagosome. These radicals were chosen because the necessary rate parameters either have been measured or could be reasonably estimated. The calculations show that .OH radical cannot be an effective bactericide unless generated in the immediate vicinity of the bacterial surface because its extreme reactivity precludes any significant diffusion. The HCO3. radical, however, is predicted to be a very effective toxin, even when relatively high concentrations of oxidant scavengers are present in the phagosomal fluid. In the absence of complicating features, the reactivity patterns of other less reactive oxidants (e.g., metal oxo or peroxo complex ions) are predicted to be very similar, although quantitative analysis is precluded by the lack of relevant rate data. For these oxidants, the predicted intraphagosomal toxicities differ markedly from toxicities measured in dilute bacterial suspensions because differences in mean diffusion lengths of the oxidants are unimportant in environments with the dimensions of phagosomes, but very important under in vitro conditions. The model is general and can be applied to other reactions occurring in similar microheterogeneous cellular and subcellular environments.