Effects of aldo-keto reductase family 1 member A on osteoblast differentiation associated with lactate production in MC3T3-E1 preosteoblastic cells.

Aldo-keto reductase family 1 member A (AKR1A) is an NADPH-dependent aldehyde reductase widely expressed in mammalian tissues. In this study, induced differentiation of MC3T3-E1 preosteoblasts was found to increase AKR1A gene expression concomitantly increased NOx- (nitrite + nitrate), increased glucose uptake, increased [NAD(P)+]/[NAD(P)H] and lactate production but decreased reactive oxygen species (ROS) without changes in endothelial nitric oxide synthase (eNOS) expression in differentiated osteoblasts (OBs). A study using gain- and loss-of-function MC3T3-E1 cells indicated that AKR1A is essential for modulating OB differentiation and gene expression of collagen 1 A1, receptor activator of nuclear factor kappa-B ligand, and osteoprotegerin in OBs. Immunofluorescence microscopy also revealed that changes in AKR1A expression altered extracellular collagen formation in differentiated OBs. Consistently, analyses of alkaline phosphatase activity and calcium deposits of matrix mineralization by Alizarin Red S staining verified that AKR1A is involved in the regulation of OB differentiation and bone matrix formation. In addition, AKR1A gene alterations affected the levels of NOx-, eNOS expression, glucose uptake, [NAD(P)+]/[NAD(P)H] dinucleotide redox couples, lactate production, and ROS in differentiated OBs. Herein, we report that AKR1A-mediated denitrosylation may play a role in the regulation of lactate metabolism as well as redox homeostasis in cells, providing an efficient way to quickly gain energy and to significantly reduce oxidative stress for OB differentiation.

Effects of varying gelatin coating concentrations on RANKL induced osteoclastogenesis.

Here, we assessed the effects of varying concentrations of gelatin coating on Receptor Activator of Nuclear Factor κ-B Ligand (RANKL)-induced RAW264.7 murine macrophage differentiation into osteoclast (OC) via osteoclastogenesis. The microstructures of coating surfaces with different concentrations of gelatin were examined by scanning electron microscopy and atomic force microscopy. Increased gelatin coating concentrations led to decreased gel rigidity but increased surface adhesion force attenuated OC differentiation and the decreased actin ring formation in RANKL-induced osteoclastogenesis. The decreased actin ring formation is associated with decreased lysosomal-associated membrane protein 1 (LAMP1) activity and bone resorption in the differentiated OCs with different gelatin coating concentrations as compared to the cells differentiated without gelatin coatings. In addition, increasing concentrations of gelatin coating attenuated the medium TGF-ß1 protein levels and the expression levels of TGF-ß and type-I (R1) and type-II (R2) TGF-ß receptors in OCs, suggesting the gelatin-induced suppression of TGF-ß signaling for the regulation of RNAKL-induced OC differentiation. Taken together, these findings showed that changes in gelatin coating concentrations, which were associated with altered gel thickness and substrate rigidity, might attenuate TGF-ß signaling events to modulate OC differentiation and concomitant actin ring formation and bone matrix resorption in RANKL-induced osteoclastogenesis.

Postoperative spinal deep wound infection: a six-year review of 3230 selective procedures.

BACKGROUND: Postoperative wound infection remains a troublesome but common complication after spinal surgery. This study presents the 6-year experience of our surgical team with post-operative deep wound infection in Taipei Veterans General Hospital. METHODS: Of 3230 selected operations, 72 cases of wound infection were identified. Thirty patients with deep wound infection were reviewed, including 17 men and 13 women at a mean age of 32 years. The pre-operative diagnoses included spondylolisthesis, scoliosis, spinal stenosis, herniated inter-vertebral disc, spinal fracture and adjacent syndrome. RESULTS: In this report, different deep wound infection rates were compared between different operative procedures including (1) posterior decompression with fixation and fusion, 1.15%. (2) simple decompression (laminectomy) and disectomy, 0.37%, (3) revision fixation with decompression, 4.4%, and (4) removal of implant. 0.33%. The onset of infection sign was divided into 3 groups: (1) acute (< 2 weeks), 43.3%, (2) subacute (2-4 weeks), 40%, and (3) chronic (> 4 weeks), 16.6%. In 11 patients with deep wound infection, no bacteria was cultured, while 14 patients had Methicillin-resistant Staphylococcus aureus and another 3 patients had lower-grade toxic Staphylococcus aureus. All patients received debridement followed by delayed wound closure with effective antibiotics. Instruments were removed in only 8 patients. Twenty seven cases were cured after treatment but 3 patients expired in poor condition. CONCLUSIONS: In this series, total deep wound infection was 0.9% in our 6-year experience. The incidence of postoperative spinal infection increased with the complexity of the procedure. Most patients got completely disease free with antibiotics and surgical treatment.