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We developed a method for measurement of skin DNA synthesis, reflecting cell division, in conscious rabbits by infusing D-[U-13C6]glucose and L-[15N]glycine. Cutaneous protein synthesis was simultaneously measured by infusion of L-[ring-²H5]phenylalanine. Rabbits were fitted with jugular venous and carotid arterial catheters, and were studied during the infusion of an amino acid solution (10% Travasol). The fractional synthetic rate (FSR) of DNA from the de novo nucleotide synthesis pathway, a reflection of total cell division, was 3.26 ± 0.59%/d in whole skin and 3.08 ± 1.86%/d in dermis (P = 0.38). The de novo base synthesis pathway accounted for 76 and 60% of the total DNA FSR in whole skin and dermis, respectively; the contribution from the base salvage pathway was 24% in whole skin and 40% in dermis. The FSR of protein in whole skin was 5.35 ± 4.42%/d, which was greater (P < 0.05) than that in dermis (2.91 ± 2.52%/d). The FSRs of DNA and protein were not correlated (P = 0.33), indicating that cell division and protein synthesis are likely regulated by different mechanisms. This new approach enables investigations of metabolic disorders of skin diseases and regulation of skin wound healing by distinguishing the 2 principal components of skin metabolism, which are cell division and protein synthesis. [ABSTRACT FROM AUTHOR]

We developed gas chromatography–mass spectrometry assays for the concentration and mass isotopomer distribution of propionyl-CoA, methylmalonyl-CoA, and succinyl-CoA in tissues. The assays involves perchloric acid extraction of the tissue, spiking the extract with [2H5]propionyl-CoA and [2H4]succinyl-CoA internal standards, and isolation of short-chain acyl-CoA fraction on an oligonucleotide purification cartridge. Propionyl-CoA is reacted with sarcosine and the formed N-propionylsarcosine is assayed as its pentafluorobenzyl derivative. Methylmalonyl-CoA and succinyl-CoA are hydrolyzed and the corresponding acids assayed as tert-butyl dimethylsilyl derivatives. The assay was applied to a study of [U-13C3]propionate metabolism in perfused rat livers. While propionyl-CoA is only M3 labeled, succinyl-CoA is M3, M2, and M1 labeled because of isotopic exchanges in the citric acid cycle. Methylmalonyl-CoA is M3 and M2 labeled, reflecting reversal of S-methylmalonyl-CoA mutase. Thus, our assays allow measuring the turnover of the coenzyme A derivatives involved in anaplerosis of the citric acid cycle via precursors of propionyl-CoA, i.e., propionate, odd-chain fatty acids, isoleucine, threonine, and valine. [Copyright &y& Elsevier]

Background: Hemorrhagic shock and trauma are associated with acidosis and altered coagulation. A fall in pH has been reported to attenuate the activity of recombinant activated Factor VII (rFVIIa) in vitro. However, it is not known if acidosis induced by hemorrhagic shock or infusion of HCl attenuates FVIIa activity in vivo. The purpose of this study was to determine if acidosis, induced by two methods, affects recombinant FVIIa (rFVIIa) activity in swine, and if correction of the pH restores rFVIIa activity to normal., Methods: Acidosis was induce in anesthetized swine in two separate models: 1) HCl infusion (n=10) and 2) hemorrhage/hypoventilation (n=8). Three groups per model were used: Control (pH7.4), Acidosis (arterial pH7.1) and Acidosis-Corrected (bicarbonate infusion to return pH from 7.1 to 7.4). Pigs were then injected with rFVIIa (90 μg/kg) or vehicle (saline) at target pH and arterial blood samples were taken for measurement of coagulation function, including Thromboelastography -TEG, Thrombin Generation, Activated Clotting Time, Prothrombin Time, activated Partial Thromboplastin Time, Fibrinogen Concentration and Platelet count before and 5min after injection of rFVIIa., Results: Acidosis led to a hypocoagulation as measured by almost all coagulation parameters in both models. Furthermore, the change in coagulation function produced after infusion of rFVIIa was not different between control, acidosis and acidosis-corrected groups for all coagulation parameters measured., Conclusion: Acidosis associated with hemorrhagic shock or HCl infusion led to a hypocoagulation that was not corrected with bicarbonate infusion. Furthermore, acidosis did not affect rFVIIa function, and correction of the acidosis with bicarbonate had no effect on rFVIIa function in these models. This suggests that in vivo acidosis did not diminish rFVIIa function.

Objective: Uncontrolled bleeding from coagulopathy signals imminent death in severely injured patients. Acidosis is an important predictor of coagulopathy, but the underlying contributing mechanisms are unclear. This study was designed to investigate the effects of acidosis on fibrinogen metabolism and coagulation function in a swine model., Methods: Twelve pigs were randomly divided into the control (n = 6) and acid (n = 6) groups. Acidosis of pH 7.1 was induced by infusion of 0.2 M HCl in lactated Ringer solution in the acid group. Afterward, an infusion of stable isotope 1-13C-phenylalanine (6 hours) and d5-phenylalanine (4 hours) was performed. Blood samples were withdrawn hourly to quantify fibrinogen synthesis and degradation rates using gas chromatograph and mass spectrometry analysis. To correlate changes in fibrinogen metabolism, coagulation changes were assessed by prolonged prothrombin time, partial activated thromboplastin time, activated clotting time, and thrombelastograph (TEG)., Results: Acidosis caused decreases in mean arterial pressure, arterial bicarbonate concentration, base excess, fibrinogen concentration, and platelet counts. Acidosis increased fibrinogen degradation rate from the control value of 4.3 +/- 1.0 mg/kg/h to 11.8 +/- 1.4 mg/kg/h (P < 0.05), with no effect on fibrinogen synthesis. Prolonged prothrombin time, partial activated thromboplastin time, activated clotting time were consistently prolonged by acidosis (all P < 0.05). Clotting rapidity (angle alpha in TEG) was decreased from a baseline value of 73.3 +/- 1.1 degree to 63.0 +/- 2.4 degree (P < 0.05). Clot strength (maximum amplitude in TEG) was decreased from a baseline value of 72.2 +/- 1.4 mm to 56.2 +/- 3.1 mm (P < 0.05)., Conclusions: Acidosis compromised the clotting process and accelerated fibrinogen consumption with no effect on fibrinogen production, resulting in a deficit in fibrinogen availability.