Effects of Increased Ambient Temperature During IVM and/or IVF on the In Vitro Development of Bovine Zygotes

Previous research by this group (2003) has demonstrated that heat stress during in vitro culture (IVC) significantly increased early embryo mortality. The experiments reported here examine the effects of heat treatment (HT) during in vitro maturation (IVM) and during in vitro fertilization (IVF). One 24 h cycle of HT entailed a series of 0.5°C incubator temperature increases from 39°C to 39.5°C for 2 h, to 40°C for 2 h, to 40.5°C for 4 h, 41°C for 4 h, 40.5°C for 6 h and 40°C for 6 h. This cycle mimics rectal temperatures recorded in high producing, grain fed dairy cows in hot climates. Experiment I studied the effects of one cycle of heat-treatment during IVF on the rate of cleavage of in vitro matured presumptive zygotes. Total cleavage rate in the HT group (37.8%) was lower than that of the control group (54.6%, p < 0.05). Experiment II repeated the HT of experiment I but preceded it with a cycle of HT during IVM. The total cleavage rates for control and heat treatment groups were 75.5% and 37.9%, respectively, with a significant difference of p < 0.001 identified. Experiment III examined the rates of embryonic development to ≥8-cell stage (after 72 h IVC) and to morula or blastocyst (M/B) stage (after 144 h IVC) following HT of the oocyte groups during the preceding IVM or IVF. Rates of development to ≥8-cell stage (at 72 h IVC) and to M/B stage (after 144 h IVC) for the control group were 27.5% and 35.8%. Those of IVM-only HT and IVF-only HT groups were 13.8% and 14.6%, and 8.6% and 14.3%, respectively. Both groups of heat treated embryos developed at significantly lower rates (p < 0.05) than did the control group. These results suggest that hyperthermia during oocyte maturation and/or fertilization adversely affects oocyte maturation and fertilization rates and retards further embryonic development

Nanoceramics for blood-borne virus removal

The development of nanoscience and nanotechnology in the field of ceramics has brought new opportunities for the development of virus removal techniques. A number of nanoceramics, including nanostructured alumina, titania, zirconia etc. have been introduced for the applications in virus removal/separation. Filtration or adsorption of viruses and thus the removal of viruses through nanoceramics, such as nanoporous/mesoporous ceramic membranes, ceramic nanofibres, and ceramic nanoparticles will make it possible to produce an efficient system for virus removal from blood and with excellent chemical/thermal stability. Currently nanoceramic membranes and filters based on sol-gel alumina membranes and NanoCeram® nanofibre filters have been commercialized and applied to remove viruses from the blood. Nevertheless, filtration using nanoprous filters is limited to the removal of only free viruses in the bloodstream

Reliability of clinical measurement for assessing spinal fusion: An experimental sheep study

Study Design. A sheep study designed to compare the accuracy of static radiographs, dynamic radiographs, and computed tomographic (CT) scans for the assessment of thoracolumbar facet joint fusion as determined by micro-CT scanning. Objective. To determine the accuracy and reliability of conventional imaging techniques in identifying the status of thoracolumbar (T13-L1) facet joint fusion in a sheep model. Summary of Background Data. Plain radiographs are commonly used to determine the integrity of surgical arthrodesis of the thoracolumbar spine. Many previous studies of fusion success have relied solely on postoperative assessment of plain radiographs, a technique lacking sensitivity for pseudarthrosis. CT may be a more reliable technique, but is less well characterized. Methods. Eleven adult sheep were randomized to either attempted arthrodesis using autogenous bone graft and internal fixation (n = 3) or intentional pseudarthrosis (IP) using oxidized cellulose and internal fixation (n = 8). After 6 months, facet joint fusion was assessed by independent observers, using (1) plain static radiography alone, (2) additional dynamic radiographs, and (3) additional reconstructed spiral CT imaging. These assessments were correlated with high-resolution micro-CT imaging to predict the utility of the conventional imaging techniques in the estimation of fusion success. Results. The capacity of plain radiography alone to correctly predict fusion or pseudarthrosis was 43% and was not improved using plain radiography and dynamic radiography with also a 43% accuracy. Adding assessment by reformatted CT imaging to the plain radiography techniques increased the capacity to predict fusion outcome to 86% correctly. The sensitivity, specificity, and accuracy of static radiography were 0.33, 0.55, and 0.43, respectively, those of dynamic radiography were 0.46, 0.40, and 0.43, respectively, and those of radiography plus CT were 0.88, 0.85, and 0.86, respectively. Conclusion. CT-based evaluation correlated most closely with high-resolution micro-CT imaging. Neither plain static nor dynamic radiographs were able to predict fusion outcome accurately. © 2012 Lippincott Williams &amp; Wilkins

Generation of a MyoD knock-in reporter mouse line to study muscle stem cell dynamics and heterogeneity

Summary: Myoblast determination protein 1 (MyoD) dynamics define the activation status of muscle stem cells (MuSCs), aiding in muscle tissue regeneration after injury. However, the lack of experimental platforms to monitor MyoD dynamics in vitro and in vivo has hampered the investigation of fate determination and heterogeneity of MuSCs. Herein, we report a MyoD knock-in (MyoD-KI) reporter mouse expressing tdTomato at the endogenous MyoD locus. Expression of tdTomato in MyoD-KI mice recapitulated the endogenous MyoD expression dynamics in vitro and during the early phase of regeneration in vivo. Additionally, we showed that tdTomato fluorescence intensity defines MuSC activation status without immunostaining. Based on these features, we developed a high-throughput screening system to assess the effects of drugs on the behavior of MuSCs in vitro. Thus, MyoD-KI mice are an invaluable resource for studying the dynamics of MuSCs, including their fate decisions and heterogeneity, and for drug screening in stem cell therapy

Biomaterial scaffolds in cartilage - subchondral bone defects influencing the repair of autologous articular cartilage transplants

The repair of articular cartilage typically involves the repair of cartilage-subchondral bone tissue defects. Although various bioactive materials have been used to repair bone defects, how these bioactive materials in subchondral bone defects influence the repair of autologous cartilage transplant remains unclear. The aim of this study was to investigate the effects of different subchondral biomaterial scaffolds on the repair of autologous cartilage transplant in a sheep model. Cylindrical cartilage-subchondral bone defects were created in the right femoral knee joint of each sheep. The subchondral bone defects were implanted with hydroxyapatite-β-tricalcium phosphate (HA-TCP), poly lactic-glycolic acid (PLGA)-HA-TCP dual-layered composite scaffolds (PLGA/HA-TCP scaffolds), or autologous bone chips. The autologous cartilage layer was placed on top of the subchondral materials. After three months, the effect of different subchondral scaffolds on the repair of autologous cartilage transplant was systematically studied by investigating the mechanical strength, structural integration and histological responses. The results showed that the transplanted cartilage layer supported by HA-TCP scaffolds had better structural integration and higher mechanical strength than that supported by PLGA/HA-TCP scaffolds. Furthermore, HA-TCP supported cartilage showed higher expression of acid mucosubstances and glycol-amino-glycan (GAG) contents than that supported by PLGA/HA-TCP scaffolds. Our results suggested that the physicochemical properties, including the inherent mechanical strength and material chemistry of the scaffolds, play important roles in influencing the repair of autologous cartilage transplants. The study may provide useful information for the design and selection of proper subchondral biomaterials to support the repair of both subchondral bone and cartilage defects