Phospholipid acylhydrolases trigger membrane degradation during fungal sporogenesis

Preoperative timed single leg standing time is associated with the postoperative activity of daily living in aged disabled patients with end-stage knee osteoarthritis at six-months after undergoing total knee arthroplasty

OBJECTIVES

The aim of the present study was to investigate the effect size (ES) of total knee arthroplasty (TKA) for the symptoms and lower limb function and identify preoperative factor(s) associated with the post-operative activity of daily living (ADL) in aged patients with end-stage knee OA undergoing TKA.

METHODS

Fifty-nine aged patients with end-stage knee OA (mean age: 74.6 years) were enrolled in this study. The symptoms and lower limb function of the patients were evaluated using the Japanese Knee Osteoarthritis Measure (JKOM), the timed up and go (TUG) test and timed single-legged stance test with eyes open (TSLS) before and after six months from the operation.

RESULTS

While the ES of TKA for the improvement of pain was 2.83, the ES of TKA for the improvement of ADL, TUG and TSLS were 1.30, 0.59, and 0.49, respectively. While the post-operative ADL score was not associated with the preoperative ADL or pain scores, it was associated with the preoperative TUG and TSLS scores. A multiple regression analysis revealed that the one preoperative factor associated with the postoperative ADL was the TSLS.

CONCLUSION

The preoperative TSLS is associated with the postoperative ADL in aged disabled patients with end-stage knee OA.

Autoproteolytic Activation of a Symbiosis-regulated Truffle Phospholipase A2

Fungal phospholipases are members of the fungal/bacterial group XIV secreted phospholipases A(2) (sPLA(2)s). TbSP1, the sPLA(2) primarily addressed in this study, is up-regulated by nutrient deprivation and is preferentially expressed in the symbiotic stage of the ectomycorrhizal fungus Tuber borchii. A peculiar feature of this phospholipase and of its ortholog from the black truffle Tuber melanosporum is the presence of a 54-amino acid sequence of unknown functional significance, interposed between the signal peptide and the start of the conserved catalytic core of the enzyme. X-ray diffraction analysis of a recombinant TbSP1 form corresponding to the secreted protein previously identified in T. borchii mycelia revealed a structure comprising the five α-helices that form the phospholipase catalytic module but lacking the N-terminal 54 amino acids. This finding led to a series of functional studies that showed that TbSP1, as well as its T. melanosporum ortholog, is a self-processing pro-phospholipase A(2), whose phospholipase activity increases up to 80-fold following autoproteolytic removal of the N-terminal peptide. Proteolytic cleavage occurs within a serine-rich, intrinsically flexible region of TbSP1, does not involve the phospholipase active site, and proceeds via an intermolecular mechanism. Autoproteolytic activation, which also takes place at the surface of nutrient-starved, sPLA(2) overexpressing hyphae, may strengthen and further control the effects of phospholipase up-regulation in response to nutrient deprivation, also in the context of symbiosis establishment and mycorrhiza formation.