Perioperative Serum Calcium and Phosphorus Levels are Associated with Hospital Costs and Length of Stay after Major Abdominal Surgery

Loss of LasR function leads to decreased repression of Pseudomonas aeruginosa PhoB activity at physiological phosphate concentrations

While the Pseudomonas aeruginosa LasR transcription factor plays a role in quorum sensing (QS) across phylogenetically-distinct lineages, isolates with loss-of-function mutations in lasR (LasR- strains) are commonly found in diverse settings including infections where they are associated with worse clinical outcomes. In LasR- strains, the transcription factor RhlR, which is controlled by LasR, can be alternately activated in low inorganic phosphate (Pi) concentrations via the two-component system PhoR-PhoB. Here, we demonstrate a new link between LasR and PhoB in which the absence of LasR increases PhoB activity at physiological Pi concentrations and raises the Pi concentration necessary for PhoB inhibition. PhoB activity was also less repressed by Pi in mutants lacking different QS regulators (RhlR and PqsR) and in mutants lacking genes required for the production of QS-regulated phenazines suggesting that decreased phenazine production was one reason for decreased PhoB repression by Pi in LasR- strains. In addition, the CbrA-CbrB two-component system, which is elevated in LasR- strains, was necessary for reduced PhoB repression by Pi and a Δcrc mutant, which lacks the CbrA-CbrB-controlled translational repressor, activated PhoB at higher Pi concentrations than the wild type. The ΔlasR mutant had a PhoB-dependent growth advantage in a medium with no added Pi and increased virulence-determinant gene expression in a medium with physiological Pi, in part through reactivation of QS. This work suggests PhoB activity may contribute to the virulence of LasR- P. aeruginosa and subsequent clinical outcomes.

Association between homocysteine level and length of stay in patients with lower extremity atherosclerotic disease: a retrospective cohort study

OBJECTIVES

Homocysteine (Hcy) level has been widely identified as a risk factor associated with adverse outcomes in patients with lower extremity atherosclerotic disease (LEAD). However, there are still some knowledge gaps in research on the association between Hcy level and downstream adverse outcomes, such as length of stay (LOS). This study aims to explore whether and to what extent Hcy level is associated with LOS in patients with LEAD.

DESIGN

Retrospective cohort study.

SETTING

China.

PARTICIPANTS, PRIMARY AND SECONDARY OUTCOMES

We conducted a retrospective cohort study of 748 patients from inpatients with LEAD between January 2014 and November 2021 at the First Hospital of China Medical University in China. We used a slew of generalised linear models to evaluate the association between Hcy level and LOS.

RESULTS

The patients' median age was 68 years and 631 (84.36%) were males. A dose-response curve with an inflection point at 22.63 µmol/L was observed between Hcy level and LOS after the adjustment of potential confounders. LOS increased before Hcy level reached the inflection point (β: 0.36; 95% CI: 0.18 to 0.55; p<0.001).ConclusionOur results show that an Hcy level <22.63 µmol/L is associated with increased LOS in patients with LEAD, which was independent of some other risk factors. This might shed light on how Hcy can be used as a key marker in the comprehensive management of patients with LEAD during hospitalisation.

Outcomes of patients with post-hepatectomy hypophosphatemia: A narrative review

Phosphate is an essential electrolyte for proper mineralisation of bone, buffering of urine, and diverse cellular actions. Hypophosphatemia (HP) is a clinical spectrum which range from asymptomatic to severe complications such as neuromuscular and pulmonary complications, or even death. Post-hepatectomy HP (PHH) has been reported to be 55.5%-100%. Post-hepatectomy, there is rapid uptake of phosphate and increased mitotic counts to aid in regeneration of residual liver. Concurrently, PHH may be due to increased urinary phosphorous from activation of matrix extracellular phosphoglycoprotein in the injured liver, which decreases phosphate influx into hepatocytes to sustain adenosine triphosphate synthesis. A literature review was performed on PubMed till January 2022. We included 8 studies which reported on impact of PHH on post-operative outcomes. In patients with diseased liver, PHH was reported to have either beneficial or deleterious effects on post-hepatectomy liver failure (PHLF), morbidity and/or mortality in various cohorts. In living donor hepatectomy, PHLF was higher in PHH. Benefits of correction of PHH with reduced post-operative complications have been shown. Correction of PHH should be done based on extent of PHH. Existing studies were however heterogenous; further studies should be conducted to assess PHH on post-operative outcomes with standardized phosphate replacement regimes.