Effect of vitamin C on fracture healing in elderly Osteogenic Disorder Shionogi rats

Salmonella Typhimurium Infection Reduces the Ascorbic Acid Uptake in the Intestine

Salmonella Typhimurium infection of the gastrointestinal tract leads to damage that compromises the integrity of the intestinal epithelium and results in enterocolitis and inflammation. Salmonella infection promotes the expression of inflammasome NLRP3, leading to activation and release of proinflammatory cytokines such as IL-1β, and the infected host often displays altered nutrient levels. To date, the effect of Salmonella infection and proinflammatory cytokine IL-1β on the intestinal uptake of ascorbic acid (AA) is unknown. Our results revealed a marked decrease in the rate of AA uptake in mouse jejunum infected with Salmonella wild type (WT). However, the nonpathogenic mutant (Δ invA Δ spiB) strain did not affect AA uptake. The decrease in AA uptake due to Salmonella WT infection is accompanied by significantly lower expression of mouse (m)SVCT1 protein, mRNA, and hnRNA levels. NLRP3 and IL-1β expression levels were markedly increased in Salmonella-infected mouse jejunum. IL-1β-exposed Caco-2 cells displayed marked inhibition in AA uptake and significantly decreased hSVCT1 expression at both protein and mRNA levels. Furthermore, the activity of the SLC23A1 promoter was significantly inhibited by IL-1β exposure. In addition, GRHPR (a known SVCT1 interactor) protein and mRNA expression levels were significantly reduced in Salmonella-infected mouse jejunum. These results indicate that Salmonella infection inhibits AA absorption in mouse jejunum and IL-1β-exposed Caco-2 cells. The observed inhibitory effect may partially be mediated through transcriptional mechanisms.

Complex Regional Pain Syndrome and Distal Radius Fracture: Etiology, Diagnosis, and Treatment

Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by a constellation of signs and symptoms including pain out of proportion to the injury or insult, autonomic dysfunction, trophic changes, and impaired function. CRPS may occur following either conservative or surgical management of distal radius fractures and can significantly complicate the trajectory of a patient's recovery. Although the incidence, diagnosis, prevention, and treatment of this condition have been extensively studied, optimal methods to identify, prevent, and treat this condition remain controversial. This article reviews the available literature on the diagnosis and treatment of CRPS in distal radius fractures.

Natural medicine delivery from biomedical devices to treat bone disorders: A review

With an increasing life expectancy and aging population, orthopedic defects and bone graft surgeries are increasing in global prevalence. Research to date has advanced the understanding of bone biology and defect repair mechanism, leading to a marked success in the development of synthetic bone substitutes. Yet, the quest for functionalized bone grafts prompted the researchers to find a viable alternative that regulates cellular activity and supports bone regeneration and healing process without causing serious side-effects. Recently, researchers have introduced natural medicinal compounds (NMCs) in bone scaffold that enables them to release at a desirable rate, maintains a sustained release allowing sufficient time for tissue in-growth, and guides bone regeneration process with minimized risk of tissue toxicity. According to World Health Organization (WHO), NMCs are gaining popularity in western countries for the last two decades and are being used by 80% of the population worldwide. Compared to synthetic drugs, NMCs have a broader range of safety window and thus suitable for prolonged localized delivery for bone regeneration. There is limited literature focusing on the integration of bone grafts and natural medicines that provides detailed scientific evidences on NMCs, their toxic limits and particular application in bone tissue engineering, which could guide the researchers to develop functionalized implants for various bone disorders. This review will discuss the emerging trend of NMC delivery from bone grafts, including 3D-printed structures and surface-modified implants, highlighting the significance and potential of NMCs for bone health, guiding future paths toward the development of an ideal bone tissue engineering scaffold. STATEMENT OF SIGNIFICANCE: To date, additive manufacturing technology provids us with many advanced patient specific or defect specific bone constructs exhibiting three-dimensional, well-defined microstructure with interconnected porous networks for defect-repair applications. However, an ideal scaffold should also be able to supply biological signals that actively guide tissue regeneration while simultaneously preventing post-implantation complications. Natural biomolecules are gaining popularity in tissue engineering since they possess a safer, effective approach compared to synthetic drugs. The integration of bone scaffolds and natural biomolecules exploits the advantages of customized, multi-functional bone implants to provide localized delivery of biochemical signals in a controlled manner. This review presents an overview of bone scaffolds as delivery systems for natural biomolecules, which may provide prominent advancement in bone development and improve defect-healing caused by various musculoskeletal disorders.

A meta-analysis of randomized clinical trials on the impact of oral vitamin C supplementation on first-year outcomes in orthopedic patients

This meta-analysis aimed at investigating the impact of oral vitamin C supplementation on the post-procedural recovery of orthopedic patients, including functional outcomes and complex regional pain syndrome type I (CRPS I). Literature search using the Medline, Cochrane Library, and Embase databases from inception till March 2021 identified seven eligible randomized controlled trials with 1,361 participants. Forest plot revealed no significant difference in the functional outcomes at 6-12 months [standardized mean difference (SMD) = -0.00, 95% CI - 0.19 to 0.18, 467 patients], risk of overall complications (RR = 0.98, 95% CI 0.68 to 1.39, 426 patients), and pain severity at 3-6 months (SMD = - 0.18, 95% CI - 0.49 to 0.12, 486 patients) between patients with and without oral vitamin C supplementation. Pooled analysis showed that vitamin C treatment reduced the risk of CRPS I regardless of dosage (RR = 0.46, 95% CI 0.25 to 0.85, 1143 patients). In conclusion, the current meta-analysis demonstrated that oral vitamin C supplementation may reduce the risk of complex regional pain syndrome type I but did not improve the functional outcomes in orthopedic patients. Nevertheless, because of the small number of trials included in the present study, further large-scale clinical studies are warranted to support our findings.

Advances and Promises of Nutritional Influences on Natural Bone Repair

Impaired fracture healing continues to be a significant public health issue. This is more frequently observed in aging populations and patients with co-morbidities that can directly influence bone repair. Tremendous progress has been made in the development of biologics to enhance and accelerate the healing process; however, side-effects persist that can cause significant discomfort and tissue damage. This has been the impetus for the development of safe and natural strategies to hasten natural bone healing. Of the many possible approaches, nutrition represents a safe, affordable, and non-invasive strategy to positively influence each phase of fracture repair. However, our understanding of how healing can be hindered by malnutrition or enhanced with nutritional supplementation has lagged behind the advancements in both surgical management and the knowledge of molecular and cellular drivers of skeletal fracture repair. This review serves to bridge this knowledge gap as well as define the importance of nutrition during fracture healing. The extant literature clearly indicates that pre-existing nutritional deficiencies should be corrected, and nutritional status should be carefully monitored to prevent the development of malnutrition for the best possible healing outcome. It remains unclear, however, whether the provision of nutrients beyond sufficiency has any benefit on fracture repair and patient outcomes. The combined body of pre-clinical studies using a variety of animal models suggests a promising role of nutrition as an adjuvant therapy to facilitate fracture repair, but extensive research is needed, specifically at the clinical level, to clarify the utility of nutritional interventions in orthopedics. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:695-707, 2020.

Preoperative Ascorbic Acid Levels in Proximal Femur Fracture Patients Have No Postoperative Clinical Impact, While Ascorbic Acid Levels upon Discharge Have a Major Effect on Postoperative Outcome

Proximal femur fractures show a high prevalence in elderly patients and are associated with an elevated risk of multimorbidity and early mortality. Recovery is impaired by malnutrition and oxidative stress, which is affected by antioxidants such as ascorbic acid (AA). This study monitored AA levels during hospitalization of patients with a proximal femur to investigate the influence of AA status to the clinical outcome. AA levels of 25 elderly patients with a proximal femur fracture were measured during hospitalization using high performance liquid chromatography. Plasma samples were collected preoperatively, on the first day after surgery, on the third day after surgery and on the day of discharge. Nutritional Risk Screening 2002 (NRS) and Mini Nutritional Assessment (MNA) were assessed to evaluate the nutritional status. In patients with proximal femoral fractures, preoperative AA concentrations were significantly lower compared to elderly patients without an acute fracture. A significant decrease of 33.8% in AA plasma level was measured on the day after surgery with a significant recovery up to the time of discharge. The preoperative AA status did not have any significant effect on clinical outcome. However, inadequate AA levels (<50 µmol/L) upon discharge significantly increased the incidence and the severity of postoperative complications. These results indicate that the AA status upon discharge has a greater impact on clinical outcome than assumed, and therefore, AA supplementation during hospitalization should be considered.

Impact of vitamin C on teriparatide treatment in the improvement of bone mineral density, strength, and quality in vitamin C-deficient rats

Age-related decreases in serum levels of vitamin C (VC) may negatively affect the efficacy of anti-osteoporotic pharmacotherapy. The purpose of this study was to evaluate the effects of VC and teriparatide (TPTD) on bone mineral density (BMD), strength, and quality in VC-deficient osteogenic disorder Shionogi (ODS) rats. Six-month-old female ODS rats were divided into an untreated ODS control group, a VC group, a TPTD group, and a VC + TPTD group, based on the administration of VC and TPTD (n = 10 each). VC was given as 2.0 mg/ml supplemented water. TPTD was administered subcutaneously once a week at 30 µg/kg body weight. After 12 weeks of treatment, BMDs of the femur and lumbar spine, bone strengths of the femoral diaphysis and metaphysis, and cancellous bone quality of proximal tibiae as estimated by Fourier transform infrared spectroscopy (FTIR) were compared between groups. Compared to the ODS control group, the VC group showed significantly higher total femoral BMD, but the TPTD group showed significantly higher femoral and lumbar spinal BMD, maximum load of femoral metaphysis, and hydroxyapatite (HA) crystallinity by FTIR (p < 0.05). In addition to the increases shown in the TPTD group, the VC + TPTD group also showed significantly higher stiffness of the femoral diaphysis and breaking energy of the femoral metaphysis compared to the ODS control group (p < 0.05). These results indicated that TPTD alone increased cancellous/cortical BMD and cancellous bone strength with improvement of HA crystallinity in ODS rats, but addition of VC supplementation further improved cortical bone strength.

Vitamin C demand is increased after total knee arthroplasty: a double-blind placebo-controlled-randomized study

PURPOSE

This study was designed to determine whether perioperative supplementation of vitamin C (VC) improves range of motion (ROM) and reduces the risk of arthrofibrosis (AF) following total knee arthroplasty (TKA).

METHODS

Ninety-five patients undergoing TKA were randomized to either oral VC (1000 mg daily) or placebo for 50 days (48 VC group, 47 placebo group). The effect of VC supplementation was tested on ROM, AF, WOMAC, FJS-12, and VC plasma concentrations (VCc). VCc were analyzed in both patient groups before surgery, 4 and 7 days after surgery.

RESULTS

ROM at 1 year was not different between study groups. The prevalence of AF was 5 of 48 (10.4%) in the VC group compared to 11 of 47 (23.4%) in the placebo group (p = 0.09). VCc decreased post-operatively in the placebo group (49-12 µmol/l on day 7, p < 0.001), but not in the VC group (53-57 µmol/l). Patients with a perioperative drop of VCc ≥ 30 µmol/l developed significantly more AF at 1 year compared to patients with a VCc drop of < 30 µmol/l (p = 0.007).

CONCLUSIONS

TKA results in VC depletion. Perioperative VC supplementation prevents VCc drop in most patients undergoing TKA and may lower the incidence of AF. The clinical relevance of this study is that VC supplementation seems to be a cheap and safe adjunct to improve functional outcome after TKA.

LEVEL OF EVIDENCE

I.

TRIAL REGISTRY

The study was registered at the ISRCTN registry with study ID ISRCTN40250576.

MicroRNA-103a regulates sodium-dependent vitamin C transporter-1 expression in intestinal epithelial cells

Intestinal absorption of ascorbic acid (AA) occurs via a Na+-dependent carrier-mediated process facilitated through the human sodium-dependent vitamin C transporters-1 &-2 (hSVCT1 and hSVCT2). Many studies have shown that hSVCT1 (product of the SLC23A1 gene) is expressed on the apical membrane of polarized enterocytes where it mediates AA absorption. hSVCT1 expression levels are therefore an important determinant of physiological vitamin C homeostasis. However, little is known about posttranscriptional mechanisms that regulate hSVCT1 expression in intestinal epithelia. In this study, we investigated regulation of hSVCT1 by microRNA (miRNA). A pmirGLO-SLC23A1-3'-UTR construct transfected into human intestinal cell lines (Caco-2 and NCM460 cells) showed markedly reduced luciferase activity. Bioinformatic analysis of the SLC23A1-3'-UTR predicted five miRNA binding sites (miR-103a, miR-107, miR-328, miR-384, and miR-499-5p) in the 3'-UTR. Expression of mature miR-103a was markedly higher compared to the other four putative miRNA regulators in both intestinal cell lines and mouse jejunal mucosa. Addition of a miR-103a mimic, but not a miR-103a mutant construct, markedly reduced the luminescence of the pmirGLO-SLC23A1-3'-UTR reporter. Reciprocally, addition of a miR-103a inhibitor significantly increased luciferase reporter activity. Addition of the miR-103a mimic led to a significant inhibition in AA uptake, associated with decreased hSVCT1 mRNA and protein expression in Caco-2 cells. In contrast, the miR-103a inhibitor increased AA uptake, associated with increased levels of hSVCT1 mRNA and protein. These findings provide the first evidence for posttranscriptional regulation of hSVCT1 by miRNA in intestinal epithelial cells.

Inhibition of intestinal ascorbic acid uptake by lipopolysaccharide is mediated via transcriptional mechanisms

Ascorbic acid (AA) accumulation in intestinal epithelial cells is an active transport process mainly mediated by two sodium-dependent vitamin C transporters (SVCT-1 and SVCT-2). To date, little is known about the effect of gut microbiota generated lipopolysaccharide (LPS) on intestinal absorption of water-soluble vitamins. Therefore, the objective of this study was to investigate the effects of bacterially-derived LPS on AA homeostasis in enterocytes using Caco-2 cells, mouse intestine and intestinal enteroids models. Pre-treating Caco-2 cells and mice with LPS led to a significant decrease in carrier-mediated AA uptake. This inhibition was associated with a significant reduction in SVCT-1 and SVCT-2 protein, mRNA, and hnRNA expression. Furthermore, pre-treating enteroids with LPS also led to a marked decrease in SVCT-1 and SVCT-2 protein and mRNA expression. Inhibition of SVCT-1 and SVCT-2 occurred at least in part at the transcriptional level as promoter activity of SLC23A1 and SLC23A2 was attenuated following LPS treatment. Subsequently, we examined the protein and mRNA expression levels of HNF1α and Sp1 transcription factors, which are needed for basal SLC23A1 and SLC23A2 promoter activity, and found that they were significantly decreased in the LPS treated Caco-2 cells and mouse jejunum; this was reflected on level of the observed reduction in the interaction of these transcription factors with their respective promoters in Caco-2 cells treated with LPS. Our findings indicate that LPS inhibits intestinal carrier- mediated AA uptake by down regulating the expression of both vitamin C transporters and transcriptional regulation of SLC23A1 and SLC23A2 genes.

Combined supplementation of ascorbic acid and thyroid hormone T3 affects tenocyte proliferation. The effect of ascorbic acid in the production of nitric oxide

BACKGROUND

Tissue engineering is now increasingly focusing on cell-based treatments as promising tools to improve tendon repair. However, many crucial aspects of tendon biology remain to be understood before adopting the best experimental approach for cell-tissue engineering.

METHODS

The role played by Ascorbic Acid (AA) alone and in combination with thyroid hormone T₃ in the viability and proliferation of primary human tendon-derived cells was investigated. Human tenocyte viability was detected by Trypan blue exclusion test and cellular proliferation rate was evaluated by CFSE CellTrace™. In addition, the potential role of the AA in the production of Nitric Oxide (NO) was also examined.

RESULTS

In this in vitro model, an increase in tenocyte proliferation rate was observed as a consequence of progressively increased concentrations of AA (from 10 to 50 µg/ml). The addition of the T₃ hormone to the culture further increased tenocyte proliferation rate. In detail, the most evident effect on cellular growth was achieved using the combined supplementation of 50 µg/ml AA and 10^-7 M T₃.

CONCLUSION

We showed that the highest concentration of AA (100 and 500 µg/ml) caused cytotoxicity to human tenocytes. Moreover, it was shown that AA reduces NO synthesis. These results show that AA is a cell proliferation inducer that triggers tenocyte growth, while it reduces NO synthesis.

Molecular mechanism(s) involved in differential expression of vitamin C transporters along the intestinal tract

Mammalian cells utilize two transporters for the uptake of ascorbic acid (AA), Na⁺-dependent vitamin C transporter SVCT-1 and SVCT-2. In the intestine, these transporters are involved in AA absorption and are expressed at the apical and basolateral membrane domains of the polarized epithelia, respectively. Little is known about the differential expression of these two transporters along the anterior-posterior axis of the intestinal tract and the molecular mechanism(s) that dictate this pattern of expression. We used mouse and human intestinal cDNAs to address these issues. The results showed a significantly lower rate of carrier-mediated AA uptake by mouse colon than jejunum. This was associated with a significantly lower level of expression of SVCT-1 and SVCT-2 at the protein, mRNA, and heterogeneous nuclear RNA (hnRNA) levels in the colon than the jejunum, implying the involvement of transcriptional mechanism(s). Similarly, expression levels of SVCT-1 and SVCT-2 mRNA and hnRNA were significantly lower in human colon. We also examined the levels of expression of hepatocyte nuclear factor 1α and specificity protein 1, which drive transcription of the Slc23a1 and Slc23a2 promoters, respectively, and found them to be markedly lower in the colon. Furthermore, significantly lower levels of the activating markers for histone (H3) modifications [H3 trimethylation of lysine 4 (H3K4me3) and H3 triacetylation of lysine 9 (H3K9ac)] were observed in the Slc23a1 and Slc23a2 promoters in the colon. These findings show, for the first time, that SVCT-1 and SVCT-2 are differentially expressed along the intestinal tract and that this pattern of expression is, at least in part, mediated via transcriptional/epigenetic mechanisms.NEW & NOTEWORTHY Our findings show, for the first time, that transporters of the water-soluble vitamin ascorbic acid (i.e., the vitamin C transporters SVCT-1 and SVCT-2) are differentially expressed along the length of the intestinal tract and that the pattern of expression is mediated, at least in part, by transcriptional and epigenetic mechanism(s) affecting both Slc23a1 and Slc23a2 genes.

Effect of cefazolin and cefuroxime on fracture healing in rats

OBJECTIVE

To determine the effect of cefazolin and cefuroxime (the two most commonly used beta lactam antibiotics) at therapeutic doses in fracture healing in an animal model.

MATERIAL AND METHODS

75 adult male wistar rats (3months old) were selected. They were divided into three groups of 25 animals each (placebo, cefazolin and cefuroxime). A closed fracture was made in the middle third of the right femur of each rat and fixed with a Kirschner wire. Each group was treated with either saline (placebo), cefazolin or cefuroxime at therapeutic doses during fracture healing. Four weeks after fracture rats were killed and femora analysed through mechanical and histological testing.

RESULTS

The group treated with cefuroxime showed a lower mechanical resistance of the healing callus and a lower histological grade than placebo. The group treated with cefazoline showed a similar mechanical resistance and histological grade of callus to placebo.

CONCLUSION

Cefuroxime appear to disturb fracture healing more than cefazolin or placebo in Wistar rats. If those results are similar to human, the use of cefuroxime during fracture healing should be avoided in the clinical setting, if possible.

Combined treatment with minodronate and vitamin C increases bone mineral density and strength in vitamin C-deficient rats

Objectives

Reduced bone quality caused by vitamin C deficiency in older persons may lead to incidental fragility fractures during bisphosphonate treatment, although bisphosphonate increases bone mineral density (BMD). This study aimed to evaluate the effects of minodronate and ascorbic acid (Aa) on BMD, bone quality, and bone strength in Aa-deficient osteogenic disorder Shionogi (ODS) rats.

Methods

Six-month-old ODS rats were divided into four groups (n = 20 per group): (1) Aa supplementation (Aa⁺); (2) Aa-deficient (Aa⁻); (3) Aa supplementation and minodronate administration (Aa⁺ + Mino); and (4) Aa-deficient and minodronate administration (Aa⁻ + Mino). BMD, bone strength, bone histomorphometry, and bone quality determined using Fourier transform infrared spectroscopy imaging (FTIRI) were evaluated after 4 and 8 weeks.

Results

BMD was significantly higher in the Aa⁺ + Mino group than in the Aa⁻ group (p < 0.05). Bone strength was significantly higher in the Aa⁺ and Aa⁺ + Mino groups than in the Aa⁻ group (p < 0.05). Furthermore, bone strength was significantly higher in the Aa⁺ + Mino group than in the Aa⁻ + Mino group (p < 0.05). Minodronate treatment irrespective of Aa supplementation significantly decreased bone resorption compared with the Aa⁺ and Aa⁻ groups (p < 0.05). No significant differences in the parameters evaluated by FTIRI were observed between the groups.

Conclusions

Aa supplementation improved bone strength in ODS rats. Combined treatment with minodronate and Aa, but not minodronate alone, improved bone strength and increased BMD. Aa is required for bone health because it is essential for osteoblast differentiation.

MicroRNAs-141 and 200a regulate the SVCT2 transporter in bone marrow stromal cells

Vitamin C is a micro-nutrient which plays an important role in bone marrow stromal cell (BMSCs) differentiation to osteogenesis. This vitamin is transported into the BMSCs through the sodium dependent vitamin C transporter 2 (SVCT2). We previously reported that knockdown of the SVCT2 transporter decreases osteogenic differentiation. However, our understanding of the post-transcriptional regulatory mechanism of the SVCT2 transporter remains poor. MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate the messenger RNAs of protein-coding genes. In this study, we aimed to investigate the impact of miR-141 and miR-200a on SVCT2 expression. We found that mouse BMSCs expressed miR-141 and miR-200a and repressed SVCT2 expression at the functional level by targeting the 3'-untranslated region of mRNA. We also found that miR-141 and miR-200a decreased osteogenic differentiation. Furthermore, miRNA inhibitors increased SVCT2 and osteogenic gene expression in BMSCs. Taken together, these results indicate that both miRNAs are novel regulators of the SVCT2 transporter and play an important role in the osteogenic differentiation of BMSCs.

Atypical femur fractures: a review

Bisphosphonates are one of the most commonly prescribed medications for the treatment of osteoporosis. Their use has greatly decreased the number of osteoporosis-related vertebral and nonvertebral fractures. Recently, however, a relationship between long-term bisphosphonate use and subtrochanteric and femoral shaft fractures has been elucidated. These low-energy fractures, termed atypical femur fractures, exhibit unique characteristics in their pathophysiology, presentation, and radiographic appearance compared with more traditional high-energy femur fractures. Here we provide a review based on the most recent literature of the pathophysiology, presentation, evaluation, and management of these fractures. Despite an abundance of literature, atypical femur fractures remain difficult to treat, and surgeons must be aware of the tricks and complications associated with their management.

The influence of vitamin C on the outcome of distal radial fractures: a double-blind, randomized controlled trial

BACKGROUND

Vitamin C has been proposed to improve outcomes after a distal radial fracture by promotion of bone and soft-tissue healing and reduction of the prevalence of complex regional pain syndrome (CRPS). Our primary aim was to examine the effect of vitamin C on functional outcome after a distal radial fracture.

METHODS

A total of 336 adult patients with an acute fracture of the distal aspect of the radius were recruited over a one-year period and randomized to receive 500 mg of vitamin C or placebo daily for fifty days after the fracture. The primary outcomes were the DASH (Disabilities of the Arm, Shoulder and Hand) score at six weeks and at one year. Secondary variables included complications, wrist and finger motion, grip and pinch strength, pain, and a CRPS score.

RESULTS

There were no significant differences in patient or fracture characteristics between the treatment groups. There was no significant effect of vitamin C on the DASH score throughout the study period. At six weeks, patients in the vitamin C group with a nondisplaced fracture had a significantly greater wrist flexion deficit (p = 0.008) and pinch strength deficit (p = 0.020) and a greater rate of CRPS (p = 0.022), but there was no difference in the CRPS rate at any other time point. At twenty-six weeks, there was a higher rate of complications (p = 0.043) and greater pain with use (p = 0.045) in the patients with a displaced fracture treated with vitamin C. There was no significant difference in the time to fracture-healing.

CONCLUSIONS

This study demonstrated no significant difference at one year in the DASH score, other functional outcomes, the rate of CRPS, or osseous healing of nondisplaced or displaced distal radial fractures treated with vitamin C compared with placebo. We conclude that administration of vitamin C confers no benefit to patients with a displaced or nondisplaced fracture of the distal aspect of the radius.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Sequential analysis of oxidative stress markers and vitamin C status in acute bacterial osteomyelitis

In bacterial bone infections, excessively formed oxidants may result in local and systemic oxidative stress. Vitamin C is the major extracellular nonenzymatic antioxidant, also implicated in bone cells metabolism and viability. The physiological functions of vitamin C largely depend on its redox status. We sequentially assessed oxidative stress markers, hydroperoxides and malondialdehyde (MDA), total antioxidant activity (AOA), total vitamin C, ascorbic acid (Asc), and oxidized/reduced vitamin C ratio in 137 patients with acute osteomyelitis (OM). Compared to 52 healthy controls, in OM group baseline serum hydroperoxides, MDA and oxidized/reduced vitamin C ratio were higher whilst Asc and AOA were lower (P < 0.05, resp.). On the other side, total vitamin C levels in patients and controls were similar (P > 0.05), thereby suggesting a relative rather than absolute vitamin C deficiency in OM. During the follow-up, oxidative stress markers, AOA, and oxidizedreduced vitamin C ratio were gradually returned to normal, while there was no apparent change of total vitamin C concentrations. Persistently high values of oxidized/reduced vitamin C ratio and serum MDA were found in subacute OM. In conclusion, acute OM was associated with enhanced systemic oxidative stress and the shift of vitamin C redox status towards oxidized forms.

Knockdown of SVCT2 impairs in-vitro cell attachment, migration and wound healing in bone marrow stromal cells

Bone marrow stromal cell (BMSC) adhesion and migration are fundamental to a number of pathophysiologic processes, including fracture and wound healing. Vitamin C is beneficial for bone formation, fracture repair and wound healing. However, the role of the vitamin C transporter in BMSC adhesion, migration and wound healing is not known. In this study, we knocked-down the sodium-dependent vitamin C transporter, SVCT2, the only known transporter of vitamin C in BMSCs, and performed cell adhesion, migration, in-vitro scratch wound healing and F-actin re-arrangement studies. We also investigated the role of oxidative stress on the above processes. Our results demonstrate that both oxidative stress and down-regulation of SVCT2 decreased cell attachment and spreading. A trans-well cell migration assay showed that vitamin C helped in BMSC migration and that knockdown of SVCT2 decreased cell migration. In the in-vitro scratch wound healing studies, we established that oxidative stress dose-dependently impairs wound healing. Furthermore, the supplementation of vitamin C significantly rescued the BMSCs from oxidative stress and increased wound closing. The knockdown of SVCT2 in BMSCs strikingly decreased wound healing, and supplementing with vitamin C failed to rescue cells efficiently. The knockdown of SVCT2 and induction of oxidative stress in cells produced an alteration in cytoskeletal dynamics. Signaling studies showed that oxidative stress phosphorylated members of the MAP kinase family (p38) and that vitamin C inhibited their phosphorylation. Taken together, these results indicate that both the SVCT2 transporter and oxidative stress play a vital role in BMSC attachment, migration and cytoskeletal re-arrangement. BMSC-based cell therapy and modulation of SVCT2 could lead to a novel therapeutic approach that enhances bone remodeling, fracture repair and wound healing in chronic disease conditions.

Essential Nutrients for Bone Health and a Review of their Availability in the Average North American Diet

Osteoporosis and low bone mineral density affect millions of Americans. The majority of adults in North America have insufficient intake of vitamin D and calcium along with inadequate exercise. Physicians are aware that vitamin D, calcium and exercise are essential for maintenance of bone health. Physicians are less likely to be aware that dietary insufficiencies of magnesium, silicon, Vitamin K, and boron are also widely prevalent, and each of these essential nutrients is an important contributor to bone health. In addition, specific nutritional factors may improve calcium metabolism and bone formation. It is the authors' opinion that nutritional supplements should attempt to provide ample, but not excessive, amounts of factors that are frequently insufficient in the typical American diet.In contrast to dietary insufficiencies, several nutrients that support bone health are readily available in the average American diet. These include zinc, manganese, and copper which may have adverse effects at higher levels of intake. Some multivitamins and bone support products provide additional quantities of nutrients that may be unnecessary or potentially harmful.The purpose of this paper is to identify specific nutritional components of bone health, the effects on bone, the level of availability in the average American diet, and the implications of supplementation for each nutritional component. A summary of recommended dietary supplementation is included.

Oxidative stress and bone markers in plasma of patients with long-bone fixative surgery: role of antioxidants

It is well known that bone markers (e.g. osteocalcin and alkaline phosphatase) play a significant role in healing of bone fractures, whereas oxidative stress delay such healing. The present study aimed to investigate the effect of a mixture of antioxidants (vitamins A, C, E, and selenium) on oxidative stress parameters, and the levels of bone healing markers in the plasma of male patients following fixative surgery of long bones. Antioxidant tablets (300 µg vitamin A, 10 mg vitamin E, 60 mg vitamin C, and 75 µg selenium) were administered to groups 3 and 4 (10 patients in each) for 1 and 2 weeks, respectively, in addition to the regular postoperative treatment. Groups 1 (25 patients) and 2 (10 patients) received the regular post-operative treatment consisting of intravenous (I.V.) second generation of cephalosporin 1000 mg/day for 3 days, oral diclofenac 50 mg, and paracetamol 500 mg twice daily for 15 days. Osteocalcin level and alkaline phosphatase activity as well as antioxidant enzymes superoxide dismutase (SOD), glutathione reductase (GR), as well as glutathione (GSH), and thiobarbituric acid reactive substances (TBARS) as indices of oxidative stress, were determined in the plasma of all patients after 1 or 2 weeks of long-bone fixative surgery. The results revealed that osteocalcin level and the activity of alkaline phosphatase were markedly increased in the plasma of patients who received antioxidants for 2 weeks. In addition, after 1 and/or 2 weeks, the levels of TBARS were significantly lower in the antioxidant-treated patients compared with those who did not receive antioxidants. On the other hand, the activities of SOD and GR were markedly elevated in plasma of patients who received antioxidants after 1 or 2 weeks compared with patients who received regular therapy. Moreover, the level of plasma GSH was markedly increased only after 2 weeks in patients who received antioxidants. It is concluded that administration of antioxidant vitamins A, E, and C in addition to selenium could accelerate bone healing after long-bone fixative surgery. Therefore, antioxidants should be considered in designing therapeutic protocols in post-operative bone surgery.

High-dose vitamin C supplementation accelerates the Achilles tendon healing in healthy rats

INTRODUCTION

This experimental study was performed to assess, whether or not, vitamin C, required during the collagen synthesis, would influence the Achilles tendon healing in a healthy rat model.

MATERIALS AND METHODS

The right Achilles tendons of 42 healthy female Wistar Albino rats were completely ruptured. The rats were randomly divided into the vitamin C and control groups and both groups included third, tenth and twenty-first day subgroups. One hundred and fifty milligrams (1.5 cc) of vitamin C and 1.5 cc % 0.9 NaCl were injected once for every 2 days for the vitamin C and control groups, respectively. Qualitative and quantitative microscopic comparisons of the repair tissues of both groups were made on the mentioned days.

RESULTS

Angiogenesis was more evident on the third day in the vitamin C group. There was a significant difference between the control and vitamin C groups regarding the type I collagen production on the tenth day. The structure of the repair tissue was almost in the form of regular dense connective tissue at the end of twenty-first day in the vitamin C group. Mean collagen fiber diameter was considerably higher, and the number of active fibroblasts in the repair tissue was slightly elevated in the vitamin C group during the entire healing process.

CONCLUSION

High-dose vitamin C supplementation once for every 2 days has stimulating effects on the Achilles tendon healing because of early angiogenesis and increased collagen synthesis in a healthy rat model. Further studies are needed to make clear the mentioned encouraging effects of the vitamin C on the Achilles tendon healing.

Inhibition of fracture healing

This paper reviews the current literature concerning the main clinical factors which can impair the healing of fractures and makes recommendations on avoiding or minimising these in order to optimise the outcome for patients. The clinical implications are described.