Development of circumference oscillation mechanism with adjustable amplitude
According to the situation of the currently developed circumference oscillation mechanism without adjustable amplitude generally. The circular oscillation mechanism with adjustable amplitude is designed. It mainly comprises an eccentric motion mechanism and adaptive dynamic balance mechanism. The dynamic simulation and analysis is carried out on eccentric motion mechanism. The experimental results show it can achieve 0-Φ50mm adjustable amplitude and 20-350RPM adjustable oscillation frequency in the meantime, and the latter can be realized by changing eccentricity adjusting pin manually. The unbalance quality of the table can be compensated by adaptive dynamic balance mechanism in order to increase the die life. Its amplitude can be changed simply, conveniently and fast, and has the characteristics of simple and compact mechanism, rigid connection, strong bearing capacity and maintenance easily. It will be widely used in the field of biological engineering.
Improved oxygen diffusion and mechanical aggregation of tumor colonies in a novel stirred mini-bioreactor
The feasibility of a novel stirred bioreactor, the rotating aerial disk (RAD) design, was tested in this study. The novelty lies in its method of medium recirculation by convective airflow using a non-contact planer disc, a variation on a physically defined theoretical model. Computational predictions of improved oxygenation were confirmed by increases in measured dissolved oxygen, even at Reynolds numbers (100–200) where flow is mostly laminar. EL-4 mouse lymphoma cells grown for the first time as suspension cultures in the RAD bioreactor, were mechanically re-organization into dense, circular three-dimensional colonies (diameter 3–5 mm, thickness 5–800 μm), more rapidly than we have observed previously. Cell proliferation in the RAD vessels was similar to static cultures, although lactate production from glucose was significantly lower, suggesting a shift toward aerobic glycolysis. This possible reversal of the ‘Warburg effect’ was accompanied by a decrease in mitachondrial activity, perhaps reflecting a more quiescent cytoplasmic state. The RAD device may be useful as scalable, three-dimensional solid tumor model under more physiological conditions then static culture.
The bradykinin B1 receptor and the central regulation of blood pressure in spontaneously hypertensive rats
We evaluated if the brain bradykinin (BK) B1 receptor is involved in the regulation of blood pressure (BP) in conscious rats. Basal mean BP and HR were 115±2 and 165±3 mmHg and 345±10 and 410±14 beats min−1 in Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR), respectively. Intracerebroventricular (i.c.v.) injection of 1 nmol B1 receptor agonist Lys‐desArg9‐BK significantly increased the BP of WKY and SHR by 7±1 and 19±2 mmHg, respectively. One nmol Sar[D‐Phe8]‐desArg9‐BK, a kininase‐resistant B1 agonist, increased the BP of WKY and SHR by 19±2 and 17±2 mmHg, respectively and reduced HR in both strains. I.c.v. injection of 0.01 nmol B1 antagonists, LysLeu8‐desArg9‐BK or AcLys[D‐βNal7,Ile8]‐desArg9‐BK (R715), significantly decreased mean BP in SHR (by 9±2 mmHg the former and 14±3 mmHg the latter compound), but not in WKY. In SHR, the BP response to R715 was associated to tachycardia. I.c.v. Captopril, a kininase inhibitor, increased the BP of SHR, this response being partially prevented by i.c.v. R715 and reversed into a vasodepressor effect by R715 in combination with the B2 antagonist Icatibant. I.c.v. antisense oligodeoxynucleotides (ODNs) targeted to the B1 receptor mRNA decreased BP in SHR, but not in WKY. HR was not altered in either strain. Distribution of fluorescein‐conjugated ODNs was detected in brain areas surrounding cerebral ventricles. Our results indicate that the brain B1 receptor participates in the regulation of BP. Activation of the B1 receptor by kinin metabolites could participate in the pathogenesis of hypertension in SHR.