The formation of an organic coat and the release of corrosion microparticles from metallic magnesium implants

Magnesium alloys have been proposed as prospective degradable implant materials. To elucidate the complex interactions between the corroding implants and the tissue, magnesium implants were analyzed in a mouse model and the response was compared to that induced by Ti and by the resorbable polymer polyglactin, respectively. One month after implantation, distinct traces of corrosion were apparent but the magnesium implants were still intact, whereas resorbable polymeric wound suture implants were already fragmented. Analysis of magnesium implants 2 weeks after implantation by energy-dispersive X-ray spectroscopy indicated that magnesium, oxygen, calcium and phosphate were present at the implant surface. One month after implantation, the element composition of the outermost layer of the implant was indicative of tissue without detectable levels of magnesium, indicating a protective barrier function of this organic layer. In agreement with this notion, gene expression patterns in the surrounding tissue were highly similar for all implant materials investigated. However, high-resolution imaging using energy-filtered transmission electron microscopy revealed magnesium-containing microparticles in the tissue in the proximity of the implant. The release of such corrosion particles may contribute to the accumulation of calcium phosphate in the nearby tissue and to bone conductive activities of magnesium implants.     

Secondary caries detection by DIAGNOdent and radiography: a comparative in vitro study

DIAGNOdent is now well documented for detection of primary occlusal caries, but not as yet for secondary caries. The aim of this study was to investigate the application of DIAGNOdent for in vitro detection of secondary caries. The material comprised 66 extracted teeth: 48 with amalgam restorations and 18 with tooth‐colored restorations. Digital images of occlusal surfaces were captured for each specimen. The teeth were mounted in groups of 3 or 4 in plaster blocks simulating their anatomical positions. Bitewing radiographs of each block were assessed for secondary caries by 5 observers. The margins of each restoration were carefully scanned with DIAGNOdent; the site of the highest reading was localized in digital images; and the corresponding values were registered. Marginal integrity and staining were also documented. The restorations were then removed and the teeth were hemi‐sectioned. For verification, two observers working together examined all the cavities under a stereomicroscope at 16 x magnification followed by probing. Sensitivity and specificity for DIAGNOdent and conventional radiography were 0.77/0.81 and 0.65/0.81, respectively. Regarding ROC analyses, the A _z values were 0.89 and 0.72 for DIAGNOdent and radiography. For DIAGNOdent, the false‐positive fraction included only stained teeth. Cohen's kappa statistics disclosed moderate agreement between the 2 methods, with an agreement of 56%. DIAGNOdent tended to give more positive diagnoses than bitewing radiography. The results indicate that DIAGNOdent may be a helpful tool for detecting secondary caries.     

Mucosal loss with increased expression of IL-6, IL-8, and COX-2 in a formula-feeding only neonatal rat model of necrotizing enterocolitis

Introduction

The aim of our study is to establish a reliable neonatal rat model by formula feeding only for evaluation of early surgical intervention on the course of experimental necrotizing enterocolitis (NEC).

Material and methods

Newborn Sprague–Dawley rats were divided into 50 breast-fed (group 1) and 38 formula fed (Similac/Esbilac, group 2) animals. The pups were sacrificed on the 4th, 5th, and 6th day of life and the terminal intestine examined for macroscopic and histologic changes as well as cytokine expression.

Results

The histological mucosal damage was significantly higher of group 2 compared to group 1. The area of the vital mucosa of group 2 was significantly (58.57%, p < 0.001) lower compared to group 1 (75.12%). The mRNA expression of the inflammatory cytokines IL-6, IL-8 and COX-2 was significantly 2-, 5- and 10-fold increased in group 2 compared to group 1.

Discussion

Formula fed newborn rats displayed an inflammatory enterocolitis similar to human NEC. Our study demonstrates a significant loss of mucosa in animals with NEC having increased expression levels of IL-6, IL-8 and COX-2. Mucosal loss appears to be a distinct feature of experimental NEC and has to be correlated with the human disease.     

Histone deacetylase inhibitors as potential therapeutic approaches for chordoma: An immunohistochemical and functional analysis

Chordomas are rare malignancies of the axial skeleton. Therapy is mainly restricted to surgery. This study investigates histone deacetylase (HDAC) inhibitors as potential therapeutics for chordomas. Immunohistochemistry (IHC) was performed using the HDAC 1–6 antibodies on 50 chordoma samples (34 primary tumors, 16 recurrences) from 44 patients (27 male, 17 female). Pan‐HDAC‐inhibitors Vorinostat (SAHA), Panobinostat (LBH‐589), and Belinostat (PXD101) were tested for their efficacy in the chordoma cell line MUG‐Chor1 via Western blot, cell cycle analysis, caspase 3/7 activity (MUG‐Chor1, UCh‐1), cleaved caspase‐3, and PARP cleavage. p‐Values below 0.05 were considered significant. IHC was negative for HDAC1, positive for HDAC2 in most (n = 36; 72%), and for HDACs 3–6 in all specimens available (n = 43; 86%). HDAC6 expression was strongest. SAHA and LBH‐589, but not PXD101 caused a significant increase of G2/M phase cells and of cleaved caspase‐3 (p = 0.0003, and p = 0.0014 after 72 h, respectively), and a peak of caspase 3/7 activity. PARP cleavage confirmed apoptosis. The presented chordoma series expressed HDACs 2–6 with strongest expression of HDAC6. SAHA and LBH‐589 significantly increased apoptosis and changed cell cycle distribution in vitro. HDAC‐inhibitors should be further evaluated as therapeutic options for chordoma. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1999–2005, 2013     

Effect of platelet‐rich plasma on the biologic activity of the human rotator‐cuff fibroblasts: A controlled in vitro study

To assess the in vitro effect of platelet‐rich plasma (PRP) on biological activity of the human rotator cuff fibroblasts and to describe the optimal dose‐response to maximize cellular stimulation while reducing potential risk. Rotator cuff (RC) fibroblasts of n = 6 patients (mean age of 65.2 years) undergoing arthroscopic cuff tear reconstruction were cultured in vitro for 21 days and stimulated with PRP in three different concentrations (1‐, 5‐, and 10‐fold). Samples were obtained for DNA and GAG measurement at 1, 7, 14, and 21 days. The biological outcomes were regressed on the PRP concentration. The application of PRP significantly influenced the fibroblast proliferation and activity of the human rotator cuff with elevated glycosaminoglycan (GAG) and DNA levels. The dosage of PRP had the significantly highest impact on this proliferation using a onefold or fivefold application. PRP has a significant effect on fibroblast proliferation of the human rotator cuff in vitro with an optimal benefit using a onefold or fivefold PRP concentration. This study justifies further in vivo investigations using PRP at the human rotator cuff. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1249–1253, 2013     

The rational of forehead lifting in patients with chronic facial paralysis

Background

The incidence of permanent facial sequels in patients with Bell’s palsy is about 30 % and results in impaired mimic expression of both midface and forehead in varying degrees. Even at rest, most patients experience an imbalance of their facial features. In this article, static correction of brow imbalance was evaluated in patients with sequels after unilateral facial palsy.

Methods

Thirty-one patients with sequels of Bell’s palsy underwent surgery with endoscopic forehead lift. Brow position was geometrically assessed pre- and postoperatively. The validated self-assessment instrument for quality of life [Short Form 36(SF-36)] was completed prior to and after surgery. The follow-up period was 12 months.

Results

A notable improvement in the position of the brows was demonstrated over time with lasting results. All patients experienced an improvement in facial symmetry and balance at rest. However, no significant difference could be shown using SF-36 pre- and postoperatively.

Conclusion

Endoscopic forehead lift combined or as an isolated procedure is a valuable instrument to correct sequels of Bell’s palsy. Level of Evidence: Level IV, therapeutic study.     

Endoscopic neurosurgery in preterm and term newborn infants—a feasibility report

Objective

Neuroendoscopic procedures became essential in neurosurgical treatment of disturbed cerebrospinal fluid dynamics. While a vast number of papers report on the neuroendoscopic experience for adults and children, no series so far reported on techniques and indications for neonate infants. We present our experience for the feasibility of neuroendoscopic procedures in preterm and term newborn infants.

Methods

All preterm and term infants who underwent an endoscopic neurosurgical intervention prior to the 28th day after the previously estimated date of delivery were identified by retrospective review. Surgical procedures and techniques, complications, and further follow-up data are reported.

Results

During the study period, 14 infants (median age at surgery, 36+²/7 weeks of gestation) underwent 20 endoscopic procedures. The performed procedures included endoscopic septostomy (n?=?3), endoscopic shunt placement for multiloculated hydrocephalus (n?=?4), endoscopic transaqueductal stenting for isolated fourth ventricle (n?=?3), and endoscopic lavage for ventriculitis (n?=?4) or for intraventricular hemorrhage (n?=?6). No severe complications were seen, while two patients necessitating unexpected interventions during further follow-up (10 %).

Conclusions

Despite the fragility of preterm and term newborn infants, neuroendoscopic procedures may play an important role in the treatment of disturbed cerebrospinal fluid (CSF) dynamics also in this patient population. The neuroendoscopic approach may be curative in conditions like isolated lateral ventricle, may facilitate simplified and effective CSF diversion in multiloculated hydrocephalus or isolated fourth ventricle, and may be beneficial in the course of ventriculitis and intraventricular hemorrhage. Further studies must verify our experience with a bigger cohort of patients and on a multicenter basis.