Intraoperative template-molded bone flap reconstruction for patient-specific cranioplasty

Cranioplasty is a common neurosurgical procedure. Free-hand molding of polymethyl methacrylate (PMMA) cement into complex three-dimensional shapes is often time-consuming and may result in disappointing cosmetic outcomes. Computer-assisted patient-specific implants address these disadvantages but are associated with long production times and high costs. In this study, we evaluated the clinical, radiological, and cosmetic outcomes of a time-saving and inexpensive intraoperative method to mold custom-made implants for immediate single-stage or delayed cranioplasty. Data were collected from patients in whom cranioplasty became necessary after removal of bone flaps affected by intracranial infection, tumor invasion, or trauma. A PMMA replica was cast between a negative form of the patient's own bone flap and the original bone flap with exactly the same shape, thickness, and dimensions. Clinical and radiological follow-up was performed 2 months post-surgery. Patient satisfaction (Odom criteria) and cosmesis (visual analogue scale for cosmesis) were evaluated 1 to 3 years after cranioplasty. Twenty-seven patients underwent intraoperative template-molded patient-specific cranioplasty with PMMA. The indications for cranioplasty included bone flap infection (56%, n = 15), calvarian tumor resection (37%, n = 10), and defect after trauma (7%, n = 2). The mean duration of the molding procedure was 19 ± 7 min. Excellent radiological implant alignment was achieved in 94% of the cases. All (n = 23) but one patient rated the cosmetic outcome (mean 1.4 years after cranioplasty) as excellent (70%, n = 16) or good (26%, n = 6). Intraoperative cast-molded reconstructive cranioplasty is a feasible, accurate, fast, and cost-efficient technique that results in excellent cosmetic outcomes, even with large and complex skull defects.

Quantitative 1-Step DNA Methylation Analysis with Native Genomic DNA as Template

DNA methylation analysis currently requires complex multistep procedures based on bisulfite conversion of unmethylated cytosines or on methylation-sensitive endonucleases. To facilitate DNA methylation analysis, we have developed a quantitative 1-step assay for DNA methylation analysis.

Anatomically-Driven Soft-Tissue Simulation Strategy for Cranio-Maxillofacial Surgery Using Facial Muscle Template Model

We propose a computationally efficient and biomechanically relevant soft-tissue simulation method for cranio-maxillofacial (CMF) surgery. A template-based facial muscle reconstruction was introduced to minimize the efforts on preparing a patient-specific model. A transversely isotropic mass-tensor model (MTM) was adopted to realize the effect of directional property of facial muscles in reasonable computation time. Additionally, sliding contact around teeth and mucosa was considered for more realistic simulation. Retrospective validation study with postoperative scan of a real patient showed that there were considerable improvements in simulation accuracy by incorporating template-based facial muscle anatomy and sliding contact.

Lipid remodelling of glycosylphosphatidylinositol (GPI) glycoconjugates in procyclic-form trypanosomes: biosynthesis and processing of GPIs revisited

The African trypanosome, Trypanosoma brucei, has been used as a model to study the biosynthesis of GPI (glycosylphosphatidylinositol) anchors. In mammalian (bloodstream)-form parasites, diacyl-type GPI precursors are remodelled in their lipid moieties before attachment to variant surface glycoproteins. In contrast, the GPI precursors of insect (procyclic)-form parasites, consisting of lyso-(acyl)PI (inositol-acylated acyl-lyso-phosphatidylinositol) species, remain unaltered before protein attachment. By using a combination of metabolic labelling, cell-free assays and complementary MS analyses, we show in the present study that GPI-anchored glycoconjugates in T. congolense procyclic forms initially receive tri-acylated GPI precursors, which are subsequently de-acylated either at the glycerol backbone or on the inositol ring. Chemical and enzymatic treatments of [3H]myristate-labelled lipids in combination with ESI-MS/MS (electrospray ionization-tandem MS) and MALDI-QIT-TOF-MS3 (matrix-assisted laser-desorption ionization-quadrupole ion trap-time-of-flight MS) analyses indicate that the structure of the lipid moieties of steady-state GPI lipids from T. congolense procyclic forms consist of a mixture of lyso-(acyl)PI, diacyl-PI and diacyl-(acyl)PI species. Interestingly, some of these species are myristoylated at the sn-2 position. To our knowledge, this is the first demonstration of lipid remodelling at the level of protein- or polysaccharide-linked GPI anchors in procyclic-form trypanosomes.

Intraoperative Patient-Specific Reconstruction of Partial Bone Flap Defects After Convexity Meningioma Resection

OBJECTIVE: To evaluate implant accuracy and cosmetic outcome of a new intraoperative patient-specific cranioplasty method after convexity meningioma resection. METHODS: The patient's own bone flap served as a template to mold a negative form with the use of polymethyl methacrylate (PMMA). The area of bone invasion was determined and broadly excised under white light illumination with a safety margin of at least 1 cm. The definitive replica was cast within the remaining bone flap frame and the imprint. Clinical and radiologic follow-up examinations were performed 3 months after surgery. RESULTS: Four women and two men (mean age 51.4 years ± 12.8) underwent reconstruction of bone flap defects after meningioma resection. Mean duration of intraoperative reconstruction of the partial bone flap defects was 19 minutes ± 4 (range 14-24 minutes). Implant sizes ranged from 17-35 cm(2) (mean size 22 cm(2) ± 8). Radiologic and clinical follow-up examinations revealed excellent implant alignment and favorable cosmesis (visual analogue scale for cosmesis [VASC] = 97 ± 5) in all patients. CONCLUSIONS: Patient-specific reconstruction of partial bone flap defects after convexity meningioma resection using the presented intraoperative PMMA cast method resulted in excellent bony alignment and a favorable cosmetic outcome. Relatively low costs and minimized operation time for adjustment and insertion of the cranioplasty implant justify use of this method in small bony defects as well.

qPCR-based mitochondrial DNA quantification: Influence of template DNA fragmentation on accuracy

Real-time PCR (qPCR) is the method of choice for quantification of mitochondrial DNA (mtDNA) by relative comparison of a nuclear to a mitochondrial locus. Quantitative abnormal mtDNA content is indicative of mitochondrial disorders and mostly confines in a tissue-specific manner. Thus handling of degradation-prone bioptic material is inevitable. We established a serial qPCR assay based on increasing amplicon size to measure degradation status of any DNA sample. Using this approach we can exclude erroneous mtDNA quantification due to degraded samples (e.g. long post-exicision time, autolytic processus, freeze-thaw cycles) and ensure abnormal DNA content measurements (e.g. depletion) in non-degraded patient material. By preparation of degraded DNA under controlled conditions using sonification and DNaseI digestion we show that erroneous quantification is due to the different preservation qualities of the nuclear and the mitochondrial genome. This disparate degradation of the two genomes results in over- or underestimation of mtDNA copy number in degraded samples. Moreover, as analysis of defined archival tissue would allow to precise the molecular pathomechanism of mitochondrial disorders presenting with abnormal mtDNA content, we compared fresh frozen (FF) with formalin-fixed paraffin-embedded (FFPE) skeletal muscle tissue of the same sample. By extrapolation of measured decay constants for nuclear DNA (λnDNA) and mtDNA (λmtDNA) we present an approach to possibly correct measurements in degraded samples in the future. To our knowledge this is the first time different degradation impact of the two genomes is demonstrated and which evaluates systematically the impact of DNA degradation on quantification of mtDNA copy number.