The leucine aminopeptidase of Staphylococcus aureus is secreted and contributes to biofilm formation

SummaryBackgroundStaphylococcus aureus has emerged as a major drug-resistant pathogen in hospital- and community-acquired infections. Leucine aminopeptidase (LAP) is known to be essential for survival of the bacteria; however the LAP of S. aureus has not been extensively characterized. In this study, we report a detailed characterization of the S. aureus LAP.MethodsLAP from S. aureus was cloned, purified, and further biochemically characterized. The expression of LAP was analyzed by Western blotting. Growth and biofilm formation were analyzed spectrophotometrically.ResultsLAP was cloned from S. aureus and expressed as a 55 kDa protein, whereas the molecular weight of the native protein is approximately 600 kDa. LAP showed amidolytic activity against l-leucine p-nitroanilide. Optimal activity was observed at pH 8.5 and 37°C with a Vmax of 2500μmol/min/mg protein. LAP enzymatic activity was inhibited by ion chelators and enhanced by divalent metal ions, specifically Ni. LAP is secreted by laboratory as well as clinical strains. Bestatin, an inhibitor of LAP, inhibits S. aureus growth and biofilm formation.ConclusionsTo our knowledge, this is the first detailed characterization of LAP from S. aureus and suggests its importance in survival and pathogenesis

Use of Denosumab in Children With Osteoclast Bone Dysplasias: Report of Three Cases.

Denosumab has been used successfully to treat disease-associated osteoclast overactivity, including giant cell tumor of bone. Given its mechanism of action, denosumab is a potent potential treatment of other osteoclast bone dysplasias including central giant cell granuloma (CGCG), aneurysmal bone cyst (ABC), and cherubism. Relatively little is known about the safety and efficacy of denosumab in patients with these conditions, especially in children. We report on 3 pediatric patients treated with denosumab over a 3-year period at UCLA Medical Center (Los Angeles and Santa Monica, CA, USA): a 12-year-old with recurrent ABC of the pelvis, a 14-year-old with CGCG of the mandible, and a 12-year-old with cherubism. All were started on a 1-year course of 15 doses 120 mg s.c., given monthly with two loading doses on day 8 and 15. All patients demonstrated rapid and pronounced clinical improvement while on denosumab, including a significant reduction in pain and sclerosis of lytic lesions on radiographs. Within 1 month of initiating therapy, 2 patients experienced hypocalcemia (Common Terminology Criteria for Adverse Events [CTCAE] grade 2) and hypophosphatemia, with 1 patient experiencing symptoms. One patient went on to experience symptomatic rebound hypercalcemia (CTCAE grade 4) 5 months after completing therapy, requiring bisphosphonates and calcitonin. For the second patient, we developed a schedule to wean denosumab involving the progressive lengthening of time between doses from 1 to 4 months in 1-month increments before cessation. We found that denosumab therapy results in significant clinical and radiographic improvement for pediatric patients with nonresectable ABC, CGCG, and cherubism. Problems with serum calcium may be more common in younger patients, with symptomatic and protracted rebound hypercalcemia after cessation of therapy the most significant. We present a potential solution to this problem with progressive spacing of doses. Potential serious adverse events from alterations in calcium homeostasis should be explored in prospective clinical trials. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research

Effect of sodic water irrigation on yield and cation composition of vetiver (Vetiveria zizanioides (L.) Nash.)

The effect of residual sodium carbonate in irrigation water on the yield and cation composition of vetiver (Vetiueria zizanioides) was studied in open bottom reinforced concrete cemented cylindrical barrels embedded in the field at Lucknow, India. While shoot and root yields of vetiver were not significantly affected with residual sodium carbonate in irrigation water, oil yield significantly decreased at the residual sodium carbonate concentration of 8 meP and above as compared to control (tube well water). The concentration of sodium was about 10 times higher in the root than in shoot tissues. The great ability of vetiver to limit sodium entry in shoot tissues and maintain sufficient potassiunl and calcium concentration at high residual sodium carbonate concentration indicate that it is a tblerant to sadie stress. &nbsp

Effect of sodic water irrigation on yield and cation composition of vetiver (Vetiveria zizanioides (L.) Nash.)

The effect of residual sodium carbonate in irrigation water on the yield and cation composition of vetiver (Vetiueria zizanioides) was studied in open bottom reinforced concrete cemented cylindrical barrels embedded in the field at Lucknow, India. While shoot and root yields of vetiver were not significantly affected with residual sodium carbonate in irrigation water, oil yield significantly decreased at the residual sodium carbonate concentration of 8 meP and above as compared to control (tube well water). The concentration of sodium was about 10 times higher in the root than in shoot tissues. The great ability of vetiver to limit sodium entry in shoot tissues and maintain sufficient potassiunl and calcium concentration at high residual sodium carbonate concentration indicate that it is a tblerant to sadie stress. &nbsp

Effect of sodic water irrigation on yield and cation composition of vetiver (Vetiveria zizanioides (L.) Nash.)

The effect of residual sodium carbonate in irrigation water on the yield and cation composition of vetiver (Vetiueria zizanioides) was studied in open bottom reinforced concrete cemented cylindrical barrels embedded in the field at Lucknow, India. While shoot and root yields of vetiver were not significantly affected with residual sodium carbonate in irrigation water, oil yield significantly decreased at the residual sodium carbonate concentration of 8 meP and above as compared to control (tube well water). The concentration of sodium was about 10 times higher in the root than in shoot tissues. The great ability of vetiver to limit sodium entry in shoot tissues and maintain sufficient potassiunl and calcium concentration at high residual sodium carbonate concentration indicate that it is a tblerant to sadie stress. &nbsp

Effect of sodic water irrigation on yield and cation composition of vetiver (Vetiveria zizanioides (L.) Nash.)

The effect of residual sodium carbonate in irrigation water on the yield and cation composition of vetiver (Vetiueria zizanioides) was studied in open bottom reinforced concrete cemented cylindrical barrels embedded in the field at Lucknow, India. While shoot and root yields of vetiver were not significantly affected with residual sodium carbonate in irrigation water, oil yield significantly decreased at the residual sodium carbonate concentration of 8 meP and above as compared to control (tube well water). The concentration of sodium was about 10 times higher in the root than in shoot tissues. The great ability of vetiver to limit sodium entry in shoot tissues and maintain sufficient potassiunl and calcium concentration at high residual sodium carbonate concentration indicate that it is a tblerant to sadie stress. &nbsp

Polymer Coating for Immobilizing Soluble Ions in a Phosphate Ceramic Product

A polymer coating is applied to the surface of a phosphate ceramic composite to effectively immobilize soluble salt anions encapsulated within the phosphate ceramic composite. The polymer coating is made from ceramic materials, including at least one inorganic metal compound, that wet and adhere to the surface structure of the phosphate ceramic composite, thereby isolating the soluble salt anions from the environment and ensuring long-term integrity of the phosphate ceramic composite