Changes in plasma dopamine-beta-hydroxylase activity during the perioperative period of cardiac surgery: an index of sympathetic nerve activity

To evaluate the usefulness of plasma dopamine-beta-hydroxylase (DBH) activity as an index of sympathetic nerve activity during cardiac operations, we examined the serial changes in plasma DBH activity, in relation to the plasma noradrenaline (NA) level and hemodynamic parameters, in patients who underwent cardiac surgery. The plasma DBH activity decreased significantly after cardiopulmonary bypass, and remained low during dopamine (DA) infusion until 72 h after the operation. However, recovery of the hemodynamic parameters, being the mean arterial pressure, heart rate and cardiac index, was seen as early as 1-3 h postoperatively. It was therefore assumed that the plasma DBH activity takes a long time to recover after an operation. The time-course changes in the plasma NA level were quite different from the changes in DBH activity, with an apparent negative correlation being observed between them. Thus, there is a possibility that exogenously administered DA, as well as increased plasma NA, might inhibit DBH activity during cardiac surgery. Moreover, since catecholamines are often administered upon completion of cardiac surgery, measurement of the plasma catecholamine level would be inappropriate for evaluating real sympathetic nerve activity. From the results of this study, it is surmised that measurement of the plasma DBH activity could be useful for estimating the intrinsic sympathetic nerve activity of patients who have undergone cardiac surgery.     

48V radionuclidic impurity in product streams from liquid cyclotron targets with titanium windows

Vanadium-48, a positron emitter with a 16.0 day half-life, was observed in the aqueous product stream from a liquid cyclotron target equipped with a titanium window, a type of target system commonly used for preparing [13N]NH3 at PET centers. The amount of 48V activity is directly related to bombardment time and beam current. It is apparently present as vanadate ion, and it is efficiently removed by anion exchange cartridges. More generally, it is likely that the specie would be present in the product stream of any titanium-window-equipped liquid target which contains water and which is bombarded with protons or deuterons. Incidental to the 48V investigation, was quantitation of 18F in the system under study.     

Cell age distribution of erythrocytes at the incidence of cerebral stroke in stroke-prone spontaneously hypertensive rats, and their glutathione peroxidase activity

OBJECTIVE: A recently described mathematical model of human amniotic fluid dynamics used known and estimated rates of fetal fluid production (lung liquid and urine) and composition (osmolality) to enable calculation of previously unmeasured routes of amniotic fluid resorption, including fetal swallowing and intramembranous (across the amnion) water flow. This "osmolar" model assumed that only free water resorption occurred across the intramembranous route. We hypothesized that intramembranous flow also may include solutes and electrolytes because significant concentration gradients exist between amniotic fluid and fetal plasma. We used mass balance analysis to determine the direction and magnitude of intramembranous sodium flux and to assess the ability of a newly described "sodium" model to predict changes in amniotic fluid volume in response to changes in intramembranous electrolyte flow. Mathematical modeling was used to predict changes in amniotic fluid volume in response to changes in intramembranous electrolyte flow. STUDY DESIGN: Model predictions were calculated using published values for human amniotic fluid and fetal urine composition and volume. Ovine studies were used to derive lung fluid volumes and composition. Fetal swallowing and intramembranous flow were independently determined using net amniotic fluid osmolar (osmolality model) and sodium (sodium model) balance. Differences between osmolality and sodium model predictions were normalized to calculate the net intramembranous sodium flux, assuming a net balance of intramembranous osmotic solute flow. RESULTS: Both sodium and osmolality models predicted swallowed volume to be greater than intramembranous flow until 28 to 32 weeks' gestation, after which the relationship reversed. However, the sodium model predicted greater intramembranous flow and lower swallowing rates compared with the osmolality model at all gestational ages. Osmolar mass balance required daily intramembranous sodium flux into the amniotic fluid, which increased with gestational age. Furthermore, assuming stable swallowing and intramembranous water flow, the model predicts that 5% increases or decreases in amniotic fluid solute concentrations caused by intramembranous flux result in polyhydramnios or oligohydramnios, respectively. CONCLUSION: Sodium and osmolality models demonstrate similarities in determinations of amniotic fluid dynamics. However, mass balance equations demonstrate a net intramembranous flow of sodium into the amniotic fluid under normal conditions. Mathematical modeling suggests that small alterations in daily intramembranous sodium flux may evoke large changes in amniotic fluid volume.     

Medicinal foodstuffs. VII. On the saponin constituents with glucose and alcohol absorption-inhibitory activity from a food garnish "Tonburi", the fruit of Japanese Kochia scoparia (L.) Schrad.: structures of scoparianosides A, B, and C

The methanolic extract of a food garnish "Tonburi", the fruit of Japanese kochia scoparia (L.) Schrad. (Chenopodiaceae), was found to inhibit the increase in serum glucose-loaded rats. Through bioassay-guided separation, momordin Ic and its 2'-O-beta-D-glucopyranoside were isolated as the active principles from this medicinal foodstuff together with three new saponins named scoparianosides A, B, and C. The structures of scoparianosides A, B, and C were elucidated on the basis of chemical and physicochemical evidence as 3 beta, 22 alpha-dihydroxyolean-12en-28-oic acid (22 alpha-hydroxyoleanolic acid), 3-O-beta-D-xylopyranosyl (1 --> 3)-beta-D-glucopyranosiduronic acid, 3 beta-hydroxyolean -18-en-28-oic acid (morolic acid), 3-O-beta-D-xylopyranosyl(1 --> 3)-beta-D -glucopyranosiduronic acid, and 3 beta-hydroxyolean-13(18)-en-28-oic acid, 3-O-beta-D-xylopyranoxyl(1 --> 3) -beta-D-glucopyranosiduronic acid. Momordin Ic and its 2'-O-beta-D-glucopyranoside, both of which are the principal saponin constituents of this medicinal foodstuffs, were found to potently inhibit glucose and ethanol absorption in rats.     

Observation of "tear-drop" fracture-dislocation of the cervical spine by computerized tomography

Five cases of "tear-drop" fracture-dislocation of the cervical spine was examined radiologically. Examination by CT scan showed a transverse fracture line in the compressed vertebral body in all cases. In three of five cases, a mid-sagittal fracture line was accompanied by this transverse fracture. Comparing these two types of fracture with neurological complications, severe complications were found among the cases having both fracture lines. On the other hand, the conventional radiographs could not show the relationship between the degree of narrowing of the spinal canal and the severity of complication.     

Chemical durability of Solid Oxide Fuel Cells: Influence of impurities on long-term performance

Because of the fuel flexibility of Solid Oxide Fuel Cells (SOFCs), various types of fuels may be applied directly or via a simple reforming process, including hydrocarbons, alcohols, coal gas, biogas, besides hydrogen. However, various types of minor constituents in practical fuels and/or from the system components can cause chemical degradation of SOFCs, such as anode and cathode poisoning phenomena. In this study, we compare the influence of various external impurities, including sulfur, chlorine, phosphorus, boron, and siloxane for anodes, and H₂O and SO₂ for cathodes, on SOFC performance to have a general overview on long-term chemical durability of SOFCs. Chemical compatibility of Ni with foreign species has also been thermochemically considered. Using common model cells, the stability of cell voltage, electrode overpotential, and ohmic loss up to 3000 h has been experimentally examined for H₂-based fuels, for hydrocarbon-based fuels, and for partially pre-reformed CH₄-based fuels. Increase in degradation rate by impurities was verified for various operational parameters. Impurity poisoning mechanisms are discussed for each specific impurity.     

A speed-sensorless vector control of induction motor operating athigh efficiency taking core loss into account

This paper proposes a speed-sensorless vector control method for an induction motor operating at high efficiency and high response, in which core loss is taken into account, and discusses the system's performance. The proposed vector control system consists of a speed-adaptive rotor-flux observer which takes core loss into account and employs a direct-field-oriented control scheme which compensates for the influence of core loss. On the basis of simulation and experimental results, we show that the proposed system can estimate motor speed even when the rotor flux is changed     

Radiation dose from 3D rotational X-ray imaging: organ and effective dose with conversion factors

The purpose of this study was to measure organ doses and the effective dose (ED) using a three-dimensional rotational X-ray (3D-RX) system and to determine the ED conversion factor from the dose area product (DAP) for skull, spine and biliary protocols. A commercial 3D-RX imaging system was used to simulate the protocols with the adult female anthropomorphic phantom. Twenty MOSFET detectors were used to measure the absorbed doses at various organ locations. The ED was calculated for each protocol and the corresponding DAP was obtained. The skin dose was the highest for all the protocols. The second highest organ doses were those of the brain for the skull, the intestine for the spine and the kidney for the biliary protocol. The ED was 0.4-0.9, 4.2-8.4 and 3.2-4.6 mSv, and the ED conversion factor was 0.06-0.09, 0.18-0.31 and 0.13-0.23 mSv Gy(-1) cm(-2) for each protocol, respectively. This data may be used to estimate the patient ED for those protocols in the 3D-RX.     

Effect of angiotensin II on Ca2+ efflux from freshly isolated adult rat cardiomyocytes: possible involvement of Na+/Ca2+ exchanger

Facial immersion testing in cold water (< 4 degrees C) was performed to study the responses of sinus cycle length to increased parasympathetic tone before and 5 min after exercise testing in 27 children. There were no episodes of sinus arrest or extrasystole during the facial immersion testing. The resting sinus cycle lengths were significantly shorter after (539 +/- 68 msec) than before (597 +/- 96 msec) exercise testing (p < 0.001). The maximal sinus cycle lengths before and after exercise testing during cold water facial immersion testing did not differ significantly (928 +/- 167 msec and 909 +/- 128 msec, respectively). Vagal chronotropic responses were calculated from the control sinus cycle lengths and the maximal sinus cycle lengths during facial immersion testing. Facial immersion caused greater prolongation of sinus cycle length after than before exercise (73 +/- 27% and 54 +/- 26%, respectively; p < 0.005). We speculate that this augmentation of vagal activity represents accentuated antagonism in these children, i.e., the same parasympathetic stimulus causes a greater response in the presence of a stronger background sympathetic activity.