No abstract

Arginine decarboxylase (ADC) is the first enzyme in the alternative route to putrescine in the polyamine biosynthesis pathway in bacteria and plants. In this study, we have focused on the effects of various types of short-term stresses on the transcript amount and specific activity of Synechocystis sp. PCC 6803 ADC. Our results reveal that the steady-state transcript accumulation and enzyme activity are not connected in a simple manner, since only photoheterotrophy and synergistic salt and high-light stress affected both parameters similarly. Changes in the steady-state ADC mRNA accumulation under the other short-term stress conditions studied had only a small impact on enzyme activity, suggesting post-translational regulation. Based on structural modeling, Synechocystis ADCs have a putative extra domain, which might be involved in the post-translational regulation of ADC activity in Synechocystis. In addition, two symmetric inter-subunit disulfide bonds seem to stabilize the dimeric structure of ADCs. There are two genes coding for ADC and agmatinase, another polyamine pathway enzyme, in Synechocystis genome, while the genes coding for ornithine decarboxylase and for some other enzymes in the polyamine pathway were not identified with homology searches.

Background: Active fluid removal has been suggested to improve prognosis following the resolution of acute circulatory failure. To standardize the deresuscitation strategy, we have implemented a routine care protocol to guide fluid removal during continuous renal replacement therapy (CRRT). We designed a before-after pilot study to evaluate the impact of this deresuscitation strategy on the cumulative fluid balance.Methods: Consecutive ICU patients suffering from fluid overload and undergoing CRRT for acute kidney injury underwent a perfusion-based deresuscitation protocol combining a restrictive intake, continuous net ultrafiltration (UFnet) of 2 mL/kg/h, and both clinical and laboratory monitoring of perfusion (early dry group, N=42) and were compared to an historical group managed according to usual practices (control group, N=45). The primary outcome was the cumulative fluid balance at day 5 or at discharge. Secondary outcomes addressed the protocol safety. Adjustments were done with inverse probability of treatment weighting propensity score analysis.Results: Adjusted cumulative fluid balance was significantly lower in the early dry group (median [IQR]: -7784 [-11833 to -2933] mL) compared to the control group (-3492 [-9935 to -1736] mL, p=0.04). The difference was mainly driven by a greater daily UFnet (31 [22-46] mL/kg/day vs. 24 [15-32] mL/kg/day, p=0.01). There was no significant difference between both groups regarding maximal arterial lactate level and maximal norepinephrine dose requirement. Conclusion: Our perfusion-based deresuscitation protocol achieved a greater negative cumulative fluid balance compared to standard practices and was hemodynamically well tolerated. Those data suggest the feasibility of an interventional randomized clinical trial using a similar protocol.