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S Sase

Publications and source records attributed to S Sase.

10 recordsLinked to original sources
PubMed2001

Low-concentration lidocaine rapidly inhibits axonal transport in cultured mouse dorsal root ganglion neurons.

BACKGROUND: Axonal transport plays a critical role in supplying materials for a variety of neuronal functions such as morphogenetic plasticity, synaptic transmission, and cell survival. In the current study, the authors investigated the effects of the analgesic agent lidocaine on axonal transport in neurites of cultured mouse dorsal root ganglion neurons. In relation to their effects, the effects of lidocaine on the growth rate of the neurite were also examined. METHODS: Isolated mouse dorsal root ganglion cells were cultured for 48 h until full growth of neurites. Video-enhanced microscopy was used to observe particles transported within neurites and to measure the neurite growth during control conditions and in the presence of lidocaine. RESULTS: Application of 30 microM lidocaine immediately reduced the number of particles transported in anterograde and retrograde axonal directions. These effects were persistently observed during the application (26 min) and were reversed by lidocaine washout. The inhibitory effect was dose-dependent at concentrations from 0.1 to 1,000 microM (IC50 = 10 microM). In Ca2+-free extracellular medium, lidocaine failed to inhibit axonal transport. Calcium ionophore A23187 (0.1 microM) reduced axonal transport in both directions. The inhibitory effects of lidocaine and A23187 were abrogated by 10 microM KN-62, a Ca2+-calmodulin-dependent protein kinase II inhibitor. Application of such low-concentration lidocaine (30 microM) for 30 min reduced the growth rate of neurites, and this effect was also blocked by KN-62. CONCLUSIONS: Low-concentration lidocaine rapidly inhibits axonal transport and neurite growth via activation of calmodulin-dependent protein kinase II.

Anesthetics, Local↗
PubMed2000

Effect of the end-tidal xenon correction method on cerebral blood flow determination.

The objective of this work is to show how the end-tidal xenon correction method contributes to determining the cerebral blood flow (CBF) values. Respiratory xenon data from 443 patients (mean age, 59.1 +/- 13.5) were analyzed using two methods: the conventional fitting method and the end-tidal correction method. For both methods, xenon saturation rate constant (Ka1) and desaturation rate constant (Ka2) were calculated for washin and washout phases respectively. By applying the correction method, both the histograms for Ka1 and Ka2 change significantly; they become to have narrower distribution with smaller mean value. As the average effect based on computer simulation, if calculated CBF values using corrected Ka1 and Ka2 are 80 cc/100 g-tissue/min for the gray matter and 20 for the white matter, those using conventional Ka1 and Ka2 become 62.8 for the gray matter and 17.9 for the white matter. By applying the end-tidal correction method, obtained CBF values increase, and the extent of increase is larger when xenon inhalation speed is slower.

Aged↗
PubMed1982

Characterization and identification of the glucose transporter of human erythrocytes.

The glucose transporter was purified from human erythrocytes (Kasahara, M. and Hinkle, P.C. (1977) J. Biol. Chem. 252, 7384-7390). The following results support the conclusion that a major protein in the purified transporter fraction, zone 4.5 is the glucose transporter (or a part of the transporter) and is different from band 3: (1) peptide maps of zone 4.5 were similar throughout the broad band in sodium dodecyl sulfate-gel electrophoresis and were different from those of band 3, (2) specific binding of cytochalasin B was found to the transporter fraction, but not to a band 3 fraction, (3) the N-terminal amino acid analysis of the transporter fraction showed a single N-terminal of lysine, whereas the band 3 fraction showed no clear N-terminal, and (4) the rabbit antibody raised against the transporter fraction formed a precipitation line with the transporter fraction, but not with the band 3 fraction. A filtration apparatus was devised for quick and accurate measurement of cytochalasin B binding, with which results comparable to those from equilibrium dialysis were obtained.

Blood Glucose↗
PubMed1982

Random distribution of the glucose transporter of human erythrocytes in reconstituted liposomes.

The glucose transporter of human erythrocytes was reconstituted with soybean phospholipids by the freeze-thaw/sonication method and the distribution of the transporter molecules in liposomes was studied. The steady state level of glucose transport in reconstituted liposomes showed saturation when increased amounts of the transporter were used for reconstitution. The saturation curve fitted well to a theoretical curve which was derived assuming a Poisson distribution of the transporter. Freeze-fracture electron micrographs showed random distribution of intramembraneous particles on liposomes, irrespective of liposome size or amount of the transporter added. A detailed study showed a parameter of the distribution (the ratio of transporter to liposome) obtained from the transport measurement can be used for the analysis of the distribution of intramembraneous particles, indicating that most of the molecules seen as particles were active in transport.

Blood Glucose↗
PubMed1982

Identification and properties of the glucose transporter of human erythrocytes.

Several lines of studies were undertaken to clarify the identity of the glucose transporter of human erythrocytes. Peptide maps of zone 4.5 which is the main component of the purified transporter fraction, were different from those of band 3. Cytochalasin B bound to the purified transporter fraction but not to band 3. Antibody raised against the purified transporter fraction cross-reacted with zone 4.5 and moderately with band 7, but not with other erythrocyte membrane proteins. These results indicate that zone 4.5 is the transporter (or a part of the transporter) and is not a fragment of band 3. With ferritin antibody electron microscopy and freeze-fracture electron microscopy, the glucose transporter were found to evenly distributed in reconstituted liposomes. Further morphological analysis coupled with transport assays showed the distribution of the transporters was random and was satisfactorily fitted to Poisson distribution, indicating reversible association of the transporters does not occur in liposomes and is not necessary for transport activity. This communication summarises our recent studies on identification and properties of the glucose transporter of human erythrocytes. A full account of the studies is published elsewhere (22, 23).

Blood Glucose↗
PubMedDate not supplied

Correction method for end-tidal xenon concentration in CBF measurements with xenon-enhanced CT.

PURPOSE: The goal of this work is to show how variations in respiratory rate and tidal volume affect calculated cerebral blood flow (CBF) values on xenon-enhanced CT. In xenon-enhanced CT examination, the patient often takes shallow and rapid breaths. Thus, it is less likely that end-tidal xenon concentration reflects arterial xenon concentration, and appropriate correction measures should be taken for the end-distal respiratory data to obtain reliable CBF values. METHOD: Preliminary breathing tests were performed using a lung phantom to determine the influence of respiratory volume and rate on end-tidal xenon concentration. Two xenon-enhanced CT studies were conducted of a healthy person with completely different respiratory manners between two studies. One was deep and slow respiration. The other was shallow and rapid respiration. RESULTS: The lung phantom results prove that deep and slow respiration is essential for the end-tidal method. The results of xenon-enhanced CT studies of the same person show that the direct use of end-tidal data for shallow and rapid respiration leads to CBF values much lower than the actual values. CONCLUSION: Differences in respiratory rate and tidal volume during xenon inhalation can significantly affect calculated CBF values on xenon-enhanced CT. With use of the correction methods described herein, these effects can be minimized. We have derived the end-tidal correction method on the assumption that a person's CBF values should be kept unchanged regardless of different respiratory manners.

Cerebrovascular Circulation↗
PubMedDate not supplied

The effect of xenon inhalation speed on cerebral blood flow obtained using the end-tidal method in xenon-enhanced CT.

PURPOSE: The purpose of this work is to show how variations in inhalation speed of xenon gas affect cerebral blood flow (CBF) values obtained using the end-tidal method on xenon-enhanced CT (Xe-CT). We tried to clarify whether arterial xenon concentration could keep up with end-tidal xenon concentration by evaluating the effect of xenon inhalation speed on calculated CBF values. METHOD: The same subject underwent two or three consecutive Xe-CT examinations, varying xenon inhalation speed. The rate constants of applied inhalation speeds were 0.1-0.15 min-1 (low speed), 0.25-0.3 min-1 (middle speed), and 1-2 min-1 (high speed), respectively. RESULTS: No significant difference was observed among the CBF values of the same subject obtained under different inhalation speeds. CONCLUSION: End-tidal xenon can closely reflect arterial xenon under the customary method of xenon supply. The end-tidal method can provide reliable absolute CBF values, assuming actual CBF values are substantially unchanged regardless of the inhalation speed variation applied in this work.

Administration, Inhalation↗