Demonstration of chondroitin sulfates degrading endo-β-glucuronidase activity in rabbit liver

AbstractReduced chondroitin sulfate was incubated with rabbit liver extracts followed by reduction once more with sodium [3H]borohydride, and then passed through a Sephadex G-100 column. Chondroitin sulfate obtained from the incubation medium at pH 4 was only slightly depolymerized and was highly radioactive. Paper Chromatographic analyses showed that glucuronic acid residues became exposed at the reducing terminal of chondroitin sulfate after incubation with the liver extracts. These results suggest that endo-β-glucuronidase activity which degrades chondroitin sulfate is present in the rabbit liver

A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats

Our goal in this study was to determine to what extent the physiologic consequences of ovariectomy (OVX) in bones are exacerbated by a lack of daily activity such as walking. We forced 14-week-old female rats to be inactive for 15 weeks with a unique experimental system that prevents standing and walking while allowing other movements. Tibiae, femora, and 4th lumbar vertebrae were analyzed by peripheral quantitative computed tomography (pQCT), microfocused X-ray computed tomography (micro-CT), histology, histomorphometry, Raman spectroscopy, and the three-point bending test. Contrary to our expectation, the exacerbation was very much limited to the cancellous bone parameters. Parameters of femur and tibia cortical bone were affected by the forced inactivity but not by OVX: (1) cross-sectional moment of inertia was significantly smaller in Sham-Inactive rat bones than that of their walking counterparts; (2) the number of sclerostin-positive osteocytes per unit cross-sectional area was larger in Sham-Inactive rat bones than in Sham-Walking rat bones; and (3) material properties such as ultimate stress of inactive rat tibia was lower than that of their walking counterparts. Of note, the additive effect of inactivity and OVX was seen only in a few parameters, such as the cancellous bone mineral density of the lumbar vertebrae and the structural parameters of cancellous bone in the lumbar vertebrae/tibiae. It is concluded that the lack of daily activity is detrimental to the strength and quality of cortical bone in the femur and tibia of rats, while lack of estrogen is not. Our inactive rat model, with the older rats, will aid the study of postmenopausal osteoporosis, the etiology of which may be both hormonal and mechanical

A control theoretical analysis of a window-based flow control mechanism for TCP connections with different propagation delays

A feedback-based congestion control mechanism is essential to realize an efficient best-effort service in high-speed networks. A window-based flow control mechanism called TCP (Transmission Control Protocol), which is a sort of feedback-based congestion control mechanism, has been widely used in the current Internet. Recently proposed TCP Vegas is another version of TCP mechanism, and can achieve better performance than the current TCP Reno. In our previous works, we have analyzed stability of a window-based flow control mechanism based on TCP Vegas in both homogeneous and heterogeneous networks. In this paper, using our analytic results, we investigate how the dynamics of the window-based flow control mechanism is affected by the difference in propagation delays of TCP connections. We also investigate the effect of various system parameters on transient performance of the window- based flow control mechanism

Stability and Transient Performance Analysis of TCP

transfer services in packed-switched networks. TCP (Transmission Control Protocol), a sort of feedback-based congestion control mechanisms, has been widely used in the current Internet. In this thesis, we are devoted to studying a congestion control mechanism of TCP, which controls a congestion level of the network by regulating a window size of a source host according to feedback information obtained from the network. Another version of TCP called TCP Vegas has been proposed and studied in the literature. It can achieve better performance than the current TCP Reno. In previous studies, however, steady-state behavior of a window-based flow control mechanism based on TCP Vegas has been analyzed for a simple network topology. In this thesis, we extend the analysis to a generic network topology where each connection has a different propagation delay and there exists multiple bottleneck links. We first derive equilibrium values of window sizes of TCP connections and the number of packets waiting in a router's buffer. We also derive throughput of each TCP connection in steady state, and investigate the effect of control parameters of TCP Vegas on fairness among TCP connections. We then present several numerical examples, showing how control parameters of TCP Vegas should be configured for achieving both stability and better transient performance

PAPER Special Issue on Traffic Control and Performance Evaluation in Internet Analysis of a Window-Based Flow Control Mechanism based on TCP Vegas in Heterogeneous Network Environment

A feedback-based congestion control mechanism is essential to realize an efficient data transfer services in packed-switched networks. TCP (Transmission Control Protocol) is a feedbackbased congestion control mechanism, and has been widely used in the current Internet. An improved version of TCP called TCP Vegas has been proposed and studied in the literature. It can achieve better performance than the current TCP Reno. In previous studies, only performance analysis of a window-based flow control mechanism based on TCP Vegas for a simple network topology has been performed. In this paper, we extend the analysis to a generic network topology where each connection is allowed to have a different propagation delay and to traverse multiple bottleneck links. We first derive equilibrium values of window sizes of TCP connections and the number of packets waiting in a router’s buffer. We also derive throughput of each TCP connection in steady state, and investigate the effect of control parameters of TCP Vegas on fairness among TCP connections. We then present several numerical examples, showing how control parameters of TCP Vegas should be configured for achieving both stability and better transient performance. key words: TCP (Transmission Control Protocol), TCP Vegas, control theory, fairness, stability, transient performanc

mechanism for TCP

control theoretical analysis of a window-based flow contro

Stability analysis of window-based flow control mechanism

has been proposed and studied in the literature. It can achieve better performance than the current TCP Reno. In our previous studies, steady-state behavior of a windowbased flow control mechanism based on TCP Vegas has been analyzed for a simple network topology. In this paper, we extend our analysis to a generic network topology where multiple bottleneck links exist. We first derive equilibrium values of a window size of a TCP connection and the number of packets waiting in a router’s buffer in steady state. We also derive throughput of each TCP connection in steady state, and investigate the effect of control parameters of TCP Vegas on fairness among TCP connections. We then present several numerical examples, showing how control parameters of TCP Vegas should be configured for achieving both stability and better transient performance.