Evaluating Oxygen Tensions Related to Bone Marrow and Matrix for MSC Differentiation in 2D and 3D Biomimetic Lamellar Scaffolds

The physiological O2 microenvironment of mesenchymal stem cells (MSCs) and osteoblasts and the dimensionality of a substrate are known to be important in regulating cell phenotype and function. By providing the physiologically normoxic environments of bone marrow (5%) and matrix (12%), we assessed their potential to maintain stemness, induce osteogenic differentiation, and enhance the material properties in the micropatterned collagen/silk fibroin scaffolds that were produced in 2D or 3D. Expression of osterix (OSX) and vascular endothelial growth factor A (VEGFA) was significantly enhanced in the 3D scaffold in all oxygen environments. At 21% O2, OSX and VEGFA expressions in the 3D scaffold were respectively 13,200 and 270 times higher than those of the 2D scaffold. Markers for assessing stemness were significantly more pronounced on tissue culture polystyrene and 2D scaffold incubated at 5% O2. At 21% O2, we measured significant increases in ultimate tensile strength (p < 0.0001) and Young's modulus (p = 0.003) of the 3D scaffold compared to the 2D scaffold, whilst 5% O2 hindered the positive effect of cell seeding on tensile strength. In conclusion, we demonstrated that the 3D culture of MSCs in collagen/silk fibroin scaffolds provided biomimetic cues for bone progenitor cells toward differentiation and enhanced the tensile mechanical properties.

Human adipose derived stem cells are superior to human osteoblasts (HOB) in bone tissue engineering on a collagen-fibroin-ELR blend

The ultrastructure of the bone provides a unique mechanical strength against compressive, torsional and tensional stresses. An elastin-like recombinamer (ELR) with a nucleation sequence for hydroxyapatite was incorporated into films prepared from a collagen - silk fibroin blend carrying microchannel patterns to stimulate anisotropic osteogenesis. SEM and fluorescence microscopy showed the alignment of adipose-derived stem cells (ADSCs) and the human osteoblasts (HOBs) on the ridges and in the grooves of microchannel patterned collagen-fibroin-ELR blend films. The Young's modulus and the ultimate tensile strength (UTS) of untreated films were 0.58 ± 0.13 MPa and 0.18 ± 0.05 MPa, respectively. After 28 days of cell culture, ADSC seeded film had a Young's modulus of 1.21 ± 0.42 MPa and UTS of 0.32 ± 0.15 MPa which were about 3 fold higher than HOB seeded films. The difference in Young's modulus was statistically significant (p: 0.02). ADSCs attached, proliferated and mineralized better than the HOBs. In the light of these results, ADSCs served as a better cell source than HOBs for bone tissue engineering of collagen-fibroin-ELR based constructs used in this study. We have thus shown the enhancement in the tensile mechanical properties of the bone tissue engineered scaffolds by using ADSCs.

Osteogenic differentiation of adipose derived stem cells on high and low aspect ratio micropatterns

Adipose derived stem cells (ADSCs) were cultured on collagen-silk fibroin films with microchannel and micropillar patterns to investigate the effects of cell morphology changes on osteogenic differentiation. Channel and pillar micropatterned films were prepared from collagen type I and silk fibroin. While higher ADSC proliferation profiles were obtained on micropillar blend film, microchannel blend films, however, caused twice higher aspect ratio and effective orientation of cells. Alkaline phosphatase activity of ADSCs was several times higher on microchannel surface when the measured activities were normalized to cell number. Effective deposition of collagen type I and mineral by the cells were observed for patterned and unpatterned films, and these extracellular matrix components were oriented along the axis of the microchannels. In conclusion, the use of collagen-fibroin blend film with microchannel topography increased the aspect ratio and alignment of cells significantly, and was also effective in the differentiation of ADSCs into osteogenic lineage.

Protein-based materials in load-bearing tissue-engineering applications

Proteins such as collagen and elastin are robust molecules that constitute nanocomponents in the hierarchically organized ultrastructures of bone and tendon as well as in some of the soft tissues that have load-bearing functions. In the present paper, the macromolecular structure and function of the proteins are reviewed and the potential of mammalian and non-mammalian proteins in the engineering of load-bearing tissue substitutes are discussed. Chimeric proteins have become an important structural biomaterial source and their potential in tissue engineering is highlighted. Processing of proteins challenge investigators and in this review rapid prototyping and microfabrication are proposed as methods for obtaining precisely defined custom-built tissue engineered structures with intrinsic microarchitecture.

Framingham risk score and severity of coronary artery disease

OBJECTIVES

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Easy-to-perform and reliable parameters are needed to predict the presence and severity of CAD and to implement efficient diagnostic and therapeutic modalities. We aimed to examine whether the Framingham risk scoring system can be used for this purpose.

METHODS

A total of 222 patients (96 women, 126 men; mean age, 59.1 ± 11.9 years) who underwent coronary angiography were enrolled in the study. Presence of > %50 stenosis in a coronary artery was assessed as critical CAD. The Framingham risk score (FRS) was calculated for each patient. CAD severity was assessed by the Gensini score. The relationship between the FRS and the Gensini score was analyzed by correlation and regression analyses.

RESULTS

The mean Gensini score was 18.9 ± 25.8, the median Gensini score was 7.5 (0-172), the mean FRS was 7.7 ± 4.2, and the median FRS was 7 (0-21). Correlation analysis revealed a significant relationship between FRS and Gensini score (r = 0.432, p < 0.0001). This relationship was confirmed by linear regression analysis (β = 0.341, p < 0.0001). A cut-off level of 7.5 for FRS predicted severe CAD with a sensitivity of 68 % and a specificity of 73.6 % (ROC area under curve: 0.776, 95 % CI: 0.706-0.845, PPV: 78.1 %, NPV: 62.3 %, p < 0.0001).

CONCLUSION

Our work suggests that the FRS system is a simple and feasible method that can be used for prediction of CAD severity. As the sample size was small in our study, further large-scale studies are needed on this subject to draw solid conclusions.

An Evaluation of P Wave Dispersion, QT, Corrected QT and Corrected QT Dispersion Intervals on the Electrocardiograms of Malnourished Adults

The aim of our study was to investigate P wave dispersion (Pwd), QT, corrected QT (QTc), QT dispersion (QTd) and corrected QT dispersion (QTcd) intervals in subjects with malnutrition diagnosed in the pre-anaesthetic assessment, compared to those without malnutrition.

A total of 76 adult patients were included. Main diagnoses, anthropometric measurement, body mass index, electrocardiogram and serum sodium, potassium, chloride, magnesium and calcium levels were recorded for all patients. Pwd, QT and QTd intervals were measured on all electrocardiogram records and QTc and QTcd intervals determined with the Bazett formula. Protein-energy malnutrition was diagnosed with the nutritional risk index.

No statistically significant difference was found between the age, gender and malignant cancer diagnosis rates between patients with malnutrition (group M) and those not suffering from malnutrition (group N) (P >0.05). Serum albumin, total protein, potassium, calcium, magnesium and chloride values of group M were found to be significantly lower than group N (P <0.05). In group M, Pwd, QT, QTc, QTd and QTcd intervals were significantly longer than in group N (P <0.001).

Patients diagnosed with malnutrition during pre-anaesthetic assessment had significantly longer Pwd, QTc and QTcd interval durations than the control group. We attribute such extended Pwd, QTc and QTcd durations in these patients to malnutrition and malnutrition-related electrolyte imbalance.

Acoustic neuroma: a review of 392 cases

A retrospective study was made of all operations for acoustic tumour over a 40-year period. A total of 392 cases are reported. Trends over time and with the size of the tumour are reported. In the current decade all but two tumours were completely resected, the mortality rate was 1.4%, 94% of patients had a good or excellent result, the facial nerve was preserved in 64% of cases (90% of these with acceptable function) and the cochlear nerve in 13.5% (some with hearing). There is a striking dependence on the size of the tumour of the likely outcome of operation.