Using rapid prototyping molds to create patient specific polymethylmethacrylate implants in cranioplasty

Cranioplasty is a commonly performed procedure. Outcomes can be improved by the use of patient specific implants, however, high costs limit their accessibility. This paper presents a low cost alternative technique to create patient specific polymethylmethacrylate (PMMA) implants using rapid prototyped mold template. We used available patient's CT-scans, one dataset without craniotomy and one with craniotomy, for computer-assisted design of a 3D mold template, which itself can be brought into the operating room and be used for fast and easy building of a PMMA implant. We applied our solution to three patients with positive outcomes and no complications.

Surface-patterned micromechanical elements by polymer injection molding with hybrid molds

Hybrid molds enable the fabrication of polymeric parts with features of different length scales by injection molding. The resulting polymer microelements combine optical or biological functionalities with designed mechanical properties. Two applications are chosen for illustration of this concept: As a first example, microelements for optical communication via fiber-to-fiber coupling are manufactured by combining two molds to a small mold insert. Both molds are fabricated using lithography and electroplating. As a second example, microcantilevers (μCs) for chemical sensing are surface patterned using a modular mold composed of a laser-machined cavity defining the geometry of the μCs, and an opposite flat tool side which is covered by a patterned polymer foil. Injection molding results in an array of 35 μm-thick μCs with microscale surface topographies. In both cases, when the mold is assembled and closed, reliefs are transferred onto one surface of the molded element whose outlines are defined by the micromold cavity. The main advantage of these hybrid methods lies in the simple integration of optical surface structures and gratings onto the surface of microcomponents with different sizes and orientations. This allows for independent development of functional properties and combinations thereof.

Design of custom-shaped vascularized tissues using microtissue spheroids as minimal building units

Tissue engineering strategies are gathering clinical momentum in regenerative medicine and are expected to provide excellent opportunities for therapy for difficult-to-treat human pathologies. Being aware of the requirement to produce larger artificial tissue implants for clinical applications, we used microtissues, produced using gravity-enforced self-assembly of monodispersed primary cells, as minimal tissue units to generate scaffold-free vascularized artificial macrotissues in custom-shaped agarose molds. Mouse myoblast, pig and human articular-derived chondrocytes, and human myofibroblast (HMF)-composed microtissues (microm3 scale) were amalgamated to form coherent macrotissue patches (mm3 scale) of a desired shape. Macrotissues, assembled from the human umbilical vein endothelial cell (HUVEC)-coated HMF microtissues, developed a vascular system, which functionally connected to the chicken embryo's vasculature after implantation. The design of scaffold-free vascularized macrotissues is a first step toward the scale-up and production of artificial tissue implants for future tissue engineering initiatives.

Cladophialophora bantiana: a rare cause of fungal brain abscess. Clinical aspects and new therapeutic options

Black molds or dematiaceous fungi are rare etiologic agents of intracerebral abscesses and such infections carry a high mortality of up to 70% despite combined surgical and antifungal therapy. While the growing use of immunosuppressive therapies and organ transplantation have caused an increase in the incidence of rare fungal cerebral infections, occurrence in immunocompetent hosts is also possible. We describe a 60-year-old female patient with a cerebral abscess caused by Cladophialophora bantiana. The case illustrates the clinical and radiological similarities between glioblastomas and brain abscesses and emphasizes the need to perform histological and microbiological studies prior to the initiation of any form of therapy. Long-term survival from cerebral black mold abscesses has been reported only when complete surgical resection was possible. The recommended antifungal treatment involves the use of amphotericin B combined with a triazole and, if possible, flucytosine. Highly-active new generation triazole antifungal compounds (voriconazole or posaconazole) are likely to offer improved survival rates for patients with rare mold infections. In particular, posaconazole could be a new therapeutic option given its better tolerance, lower toxicity and fewer drug-drug interactions. We discuss clinical, microbiological and practical pharmacological aspects and review current and evolving treatment options.

Evaluation of PCR electrospray-ionization mass spectrometry for rapid molecular diagnosis of bovine mastitis

Bovine mastitis, an inflammatory disease of the mammary gland, is one of the most costly diseases affecting the dairy industry. The treatment and prevention of this disease is linked heavily to the use of antibiotics in agriculture and early detection of the primary pathogen is essential to control the disease. Milk samples (n=67) from cows suffering from mastitis were analyzed for the presence of pathogens using PCR electrospray-ionization mass spectrometry (PCR/ESI-MS) and were compared with standard culture diagnostic methods. Concurrent identification of the primary mastitis pathogens was obtained for 64% of the tested milk samples, whereas divergent results were obtained for 27% of the samples. The PCR/ESI-MS failed to identify some of the primary pathogens in 18% of the samples, but identified other pathogens as well as microorganisms in samples that were negative by culture. The PCR/ESI-MS identified bacteria to the species level as well as yeasts and molds in samples that contained a mixed bacterial culture (9%). The sensitivity of the PCR/ESI-MS for the most common pathogens ranged from 57.1 to 100% and the specificity ranged from 69.8 to 100% using culture as gold standard. The PCR/ESI-MS also revealed the presence of the methicillin-resistant gene mecA in 16.2% of the milk samples, which correlated with the simultaneous detection of staphylococci including Staphylococcus aureus. We demonstrated that PCR/ESI-MS, a more rapid diagnostic platform compared with bacterial culture, has the significant potential to serve as an important screening method in the diagnosis of bovine clinical mastitis and has the capacity to be used in infection control programs for both subclinical and clinical disease.

Increment thickness versus dentin bond strength of bulk fill flowables

Objectives: The aim was to investigate the influence of increment thickness on shear bond strength (SBS) to dentin of a conventional and two bulk fill flowable composites. Methods: A total of 135 specimens of ground human dentin were produced (n=15/group; 3 increment thicknesses; 3 flowable composites) and the dentin surfaces were treated with the adhesive system OptiBond FL (Kerr) according to manufacturer’s instructions. Split Teflon molds (inner diameter: 3.6 mm) of 2 mm, 4 mm, or 6 mm height allowing three increment thicknesses were clamped on the dentin surfaces and filled with either the conventional flowable Filtek Supreme XTE ((XTE); 3M ESPE) or the bulk fill flowables Filtek Bulk Fill ((FBF); 3M ESPE) or SDR ((SDR); DENTSPLY Caulk). The flowable composites were light-cured for 20 s (Demi LED; Kerr) and the specimens stored for 24 h (37°C, 100% humidity). Specimens were then subjected to a SBS-test in a universal testing machine at a cross-head speed of 1 mm/min (Zwick Z010; Zwick GmbH & Co.). SBS-values were statistically analysed with a nonparametrical ANOVA followed by exact Wilcoxon rank sum tests (α=0.05). Failure mode of the specimens was determined under a stereomicroscope at 25× magnification. Results: SBS-values (MPa) at 2 mm/4 mm/6 mm increment thicknesses (mean value [standard deviation]) were for XTE: 18.8 [2.6]/17.6 [1.6]/16.7 [3.1], for FBF: 20.6 [2.7]/17.8 [2.7]/18.7 [2.9], and for SDR: 21.7 [2.6]/18.5 [2.6]/20.3 [3.0]. For all three flowable composites, 2 mm increments yielded the highest SBS-values whereas for increments of 4 mm and 6 mm no differences were detected. All specimens presented failure modes involving cohesive failure in dentin. Conclusion: The influence of increment thickness on dentin SBS was less pronounced than expected. However, the high number of cohesive failures in dentin, reflecting the efficiency of the adhesive system, suggests a limited discriminatory power of the SBS-test.

Influence of carbon enrichment on electrical conductivity and processing of polycarbosilane derived ceramic for MEMS applications

An analysis about the effect of carbon enrichment of allylhydridopolycarbosilane SMP10® with divinylbenzene (DVB) as a promising material for electrical conductive micro-electrical mechanical systems (MEMS) is presented. The liquid precursors can be micropipetted and cured in polytetrafluoroethylene (PTFE) molds to produce 14 mm diameter disc shaped samples. The effect of pyrolysis temperature and carbon content on the electrical conductivity is discussed. The addition of 28.7 wt.% of DVB was found to be the optimum amount. Carbon was preserved in the microstructure during pyrolysis and the ceramic yield increased from 77.5 to 80.5 wt.%. The electrical conductivity increased from 10−6 to 1 S/cm depending on the annealing temperature. Furthermore, the ceramic samples obtained with this composition were found to be in many cases crack free or with minimal cracks in contrast with the behavior of pure SMP10. Using the same process we demonstrate that also microsized ceramic samples can be produced.