Chlorogenic acid (CA) is one of the active ingredients in some Chinese herbal injections, which may cause allergic reactions in clinic therapy. However, the criterion of test for allergen had not been employed in current Pharmacopeia of United States, European Pharmacopeia, Japanese Pharmacopeia and British Pharmacopeia. In order to find a new way to predict allergic reactions induced by CA earlier, the guinea pigs were sensitized successively by injecting CA intravenously once a day for three times, the results were compared that of Chinese Pharmacopeia by injecting CA intraperitoneally once every other day for three times, serum IL-4 and total IgE were detected by method of enzyme linked immunosorbent assay (ELISA) before guinea pigs were challenged once by injecting the same drug intravenously. The time–effectiveness and dose–effect of allergic reactions induced by CA were also studied. We found that contents of serum IL-4 and total IgE increased significantly before guinea pigs were challenged, either in D8 after intravenous sensitization (1.5 g/l CA, 0.5 ml) or in D14 and D21 after intraperitoneal sensitization (1.5 g/l CA, 0.5 ml), and allergic reactions occurred in all guinea pigs after challenged once by injecting CA (1.5 g/l, 1.0 ml) intravenously. It provides a new way to predict whether CA (or Chinese herbal injections contained CA) can provoke allergic reactions by detecting serum IL-4 and total IgE earlier; the examination period is reduced by 1–2 weeks. It has a good prospect of application in drug emergency test.

Bone-forming osteoblasts and bone-resorbing osteoclasts play an important role during maintenance, adaptation and healing of bone, and both cell types are influenced by physical activity. The aim of the present study was to investigate the effect of a narrow mechanical stimulation window on osteoblast- and osteoclast-like cells. Primary human cells were cultured on a bone-like structure (dentine) and three-point bending with approximately 1,100 microstrain was applied to the dentine at varying frequencies (0.1 and 0.3 Hz) and duration (1, 3 and 5 min daily over 5 days) resulting in different patterns of mechanical stimulation of osteoblast- and osteoclast-like cells. The longest stimulation (5 min at 0.1 Hz) induced a significant increase in osteoblast alkaline phosphatase activity and a significant decrease in osteoprotegerin (OPG) production, and resulted in a significant increase in the soluble receptor activator of NF-κB ligand (sRANKL)/OPG ratio towards sRANKL in comparison to the unstimulated osteoblast-like cells. All stimulations caused a significant decrease in collagen type 1 synthesis. Stimulation for 1 min at 0.3 Hz decreased the fusion and resorption activity of the osteoclast-like cells. These results demonstrate a direct effect of mechanical stimuli on osteoblast-like cells as well as on osteoclast formation and activity in vitro. The change in the sRANKL/OPG ratio towards the stimulation of osteoclastogenesis stresses the necessity to investigate the effect of the same stimulation parameter on the co-culture of both cell types.

Traumatic events are a primary cause of local lesions of articular cartilage. Tissue engineered, cartilage-like structures represent an alternative to current treatment methods. The time necessary for tissue maturation and the mechanical quality of the regenerate at implantation are both critical factors for clinical success. Low-intensity pulsed ultrasound has proven to accelerate chondrogenesis in vitro. The goal of this study was to evaluate whether low-intensity pulsed ultrasound is capable of accelerating the process of cartilage maturation and increasing regenerate stability. Hyaline-like cartilage specimens were generated in vitro and subcutaneously implanted in the backs of nude mice. Twenty-eight animals received 20 min of low-intensity pulsed ultrasound treatment daily, and 28 animals received a sham treatment. Specimens were explanted after 1, 3, 6, and 12 weeks, mechanically tested with the use of an indentation test, histologically examined, and processed for RT-PCR. The Young's moduli significantly increased from 3 to 12 weeks, and at 6 weeks were comparable to those of native articular cartilage. In histological examination, specimens showed neocartilage formation. There was no significant difference between ultrasound-treated and sham-treated groups. The mechanical stability of the neocartilage specimens increased with treatment time and reached values of native cartilage after 6 weeks in vivo. Low-intensity pulsed-ultrasound stimulation showed no stimulatory effect on tissue maturation. In contrast, ultrasound-treated specimens showed a reduced Col 2 expression at 1 week and were significantly less stiff compared to native cartilage at 6 and 12 weeks. An acceleration of the maturation of tissue-engineered neocartilage in a clinical setting by means of low-intensity pulsed ultrasound therefore appears rather unrealistic.

Different fixation systems are used for fracture and defect treatment. A prerequisite for complication free healing is sufficient mechanical stability of the osteosynthesis. In vitro investigations offer the possibility of both analysing and assessing the pre-clinical fixation stability. Due to the complex loading environment in vivo, stiffness analysis should include a complete determination of the stiffness under standardised conditions.Based on a mathematical procedure to calculate the 3-D stiffness, a mechanical testing device for the 3-D loading of fixation systems was designed and integrated in the existing test set-up. The set-up consisted of a material testing machine to produce the necessary loads and an optical measurement device to detect the resulting inter-fragmentary movements. To validate the testing device, the 3-D stiffness matrices of different Ilizarov fixator configurations were determined and compared.The good reproducibility of the test was reflected in the small intra-individual variability of the stiffness components. A distinct direction dependence of the fixator stiffness was observed. Increasing the number of rings led to a stiffness increase of up to 50%, especially in bending. The presented testing device allows a complete standardised determination of the stiffness of different fixation systems. It considers the direction dependence of the stiffness and creates a prerequisite for a more direct implant comparison.

Zusammenfassung Mit Hilfe eines mechanischen Testverfahrens wurden nach Variation ausgewählter Gestaltparameter klinisch eingesetzte Fixateurkonfigurationen in vitro untersucht. Zusätzlich wurde der Einfluss der passiven Weichteile an humanen Präparaten ermittelt. Eine Erhöhung der Anzahl der Schanz-Schrauben bzw. der Kirschner-Drähte bewirkte eine vergleichbare Steigerung der Steifigkeit wie eine Erhöhung des Durchmessers der Schrauben bzw. Drähte. Wo klinisch zulässig, sind daher größere Durchmesser anstelle einer höheren Anzahl der Schrauben bzw. Drähte zu empfehlen. Eine Reduzierung des Ringdurchmessers führte zu einer Steifigkeitszunahme. Bei Verwendung von diaphysären Transportspindeln nahm allein die Axialsteifigkeit ab. Wie erwartet, verringerten Titandrähte im Vergleich zu CoCr-Drähten fast alle Steifigkeitskomponenten. Nach gegenseitigem Verspannen der äußeren Ringebenen nahm die Gesamtsteifigkeit ab. Ein asymmetrisches Vorspannen der Kirschner-Drähte bewirkte einen Spannungsabfall im benachbarten Draht. Nach Entfernen des Weichteilmantels sank die gesamte Steifigkeit der Fixation im gleichen Ausmaß wie bei einem Defekt der Fibula. Die Studie zeigt die Zusammenhänge zwischen Gestaltparametern, passivem Weichteilmantel sowie Fixationssteifigkeit und gibt Richtlinien für die Fixateurgestaltung.

Using a mechanical testing procedure, various fixator constructs were tested in vitro. In addition, the influence of the passive soft tissue structures on the fixation stiffness was determined. An increased number of Schanz' screws or Kirschner wires led to a comparable increase in stiffness than that observed with an increasing screw or wire diameter. In consequence, larger diameters should be preferred over an additional screw or wire where clinically applicable. With diaphyseal telescoping rods only the axial stiffness decreased. As expected, large ring diameters as well as titanium wires reduced stiffness components. Bracing the outer rings caused a reduction of the overall stiffness. Asymmetric pre-tensioning of the K-wires resulted in a significant reduction of tension in the neighboring wire. Removal of the soft tissues reduced stiffness to a similar extend as experienced in a fibula defect situation. The study demonstrates the correlation between design parameters, passive soft tissues and fixation stiffness and presents guidelines for an optimized fixator design.

Traumatic events are a primary cause for local lesions of articular cartilage. If treated early, restoration of the initial joint geometry and integrity may be achieved. In large defects, sufficient material is not available to bridge the affected area. Heterologeous transplantation is not well accepted due to the risk of infection and immune response. Alternatives are cartilage-like structures, which may be cultured in vitro and transplanted into the defect site. Critical to the success of these new tissues are their mechanical properties. Goals of this study were to generate a hyaline-like cartilage structure, to evaluate its performance in vivo and to verify that its cellular and material properties meet those of native cartilage. Hyaline-like cartilage specimens were generated in vitro and implanted in the backs of nude mice. Specimens were explanted after 6 and 12 weeks, mechanically tested using an indentation test and histologically examined. In mechanical testing, stiffness and failure load significantly increased between weeks 6 and 12. At 12 weeks, mechanical properties of the hyaline-like cartilage were comparable to those of native nasal septal cartilage. Compared to native articular cartilage, the engineered tissue achieved up to 30-50% in strength and mechanical stiffness. In histological examination, specimens showed neocartilage formation. The mechanical testing procedure proved to be sufficiently sensitive to identify differences in properties between cartilage specimens of different origin and at different stages of healing. As an adjunct to histological analysis, mechanical testing may be a valuable tool for judging the utility of engineered cartilage prior to a broad clinical usage.