Leucocyte distribution during sevoflurane anaesthesia

We have examined if sevoflurane anaesthesia per se modified the number of circulating leucocytes in humans. Fifty-nine patients undergoing elective surgery were anaesthetized with sevoflurane in oxygen. The inhaled concentration was increased gradually to 5% and maintained for 20 min. Arterial blood samples were obtained before induction of anaesthesia and at 20 min. While the total number of leucocytes remained constant, circulating neutrophils decreased (mean 3370 (SD 1030) mm-3 to 3170 (940) mm-3; P < 0.01) and lymphocytes increased (1870 (520) mm-3 to 2040 (580) mm-3; P < 0.01). We conclude that high concentrations of sevoflurane modified the distribution of leucocytes in anaesthetized patients.     

Increased serotonin release across the coronary bed during a nonischemic interval in patients with vasospastic angina

BACKGROUND: Platelet activation and coagulation abnormality have been observed during coronary spasm. It is crucial whether platelet activation occurs even during a nonischemic period. HYPOTHESIS: This study was designed to determine whether platelets might be activated across the coronary bed during a nonischemic interval in patients with vasospastic angina. METHODS: Plasma levels of serotonin, 6-keto-prostaglandin F1 alpha, and catecholamines in the aorta and the coronary sinus were simultaneously measured in 16 patients with vasospastic angina and 13 control patients with nonischemic heart disease. RESULTS: None of these patients showed myocardial ischemia during sampling. The difference in transcardiac plasma levels of serotonin in patients with vasospastic angina was significantly higher than that in controls (1.48 +/- 1.08 ng/ml vs. 0.07 +/- 0.12 ng/ml, respectively, p < 0.001). Coronary sinus plasma norepinephrine levels in these two groups were almost the same (204.8 +/- 110.8 pg/ml vs. 190.4 +/- 131.6 pg/ml, respectively). The ratio of 6-keto-prostaglandin F1 alpha in the coronary sinus and the aorta was not different between the two groups (1.17 +/- 0.96 in patients with vasospastic angina vs. 1.15 +/- 0.68 in controls). CONCLUSIONS: These data suggest that platelet activation across the coronary bed should be ascribed to endothelial dysfunction. Lack of compensatory enhancement of prostacyclin production might be concerned with dysfunction of coronary endothelial cells in these patients.     

Dynamic MR hepatocholangiography with the SIP Fast GRE (saturation inversion projection fast gradient echo) method

The purpose of this study was to assess the utility of dynamic MR hepatocholangiography with the Gd-EOB-DTPA enhanced SIP Fast GRE sequence in the hepatobiliary system. The SIP Fast GRE sequence was used for sequential imaging of the hepatobiliary system with a frame rate of 3 sec in a 256 x 192 matrix. Dynamic sequential acquisition was performed for 51 min before and after the injection of 30 mu mol/kg of Gd-EOB-DTPA in a rabbit. Dynamic images of the hepatobiliary system were obtained in the rabbit study. Dynamic MR hepatocholangiography provides better functional information than conventional MR cholangiography.     

Reoperation for recurrent coronary artery disease: results of 200 consecutive cases

OBJECTIVE: To quantify first-pass enhancement of cervix carcinoma using fast dynamic MRI. To assess the accuracy of dynamic contrast-enhanced colour-coded MRI for determining tumour invasion into surrounding pelvic tissues. METHODS: Gadolinium enhanced dynamic MRI at one image every 2 s was performed in 47 patients with cervical carcinoma and five controls. First-pass contrast enhancement of cervix carcinoma and surrounding pelvic tissues was quantified. Automated colour-coded images were constructed using the dynamic parameters slope, amplitude and timing of enhancement. Of 47 patients, 28 underwent surgery and colour coded images were correlated with histological findings. RESULTS: First-pass contrast enhancement imaging of cervix carcinoma required a temporal resolution of dynamic MRI of one image every 3-4 s. Cervix carcinoma first-pass was more rapid and intense than that of other pelvic tissues (P<0.001) with the exception of normal myometrium (P>0.05). Binary colour coding, however, was not reliable for tumour delineation or for accurate assessment of tumour invasion into the parametria or the bladder wall. Overestimation of the extent of tumour invasion occurred in 15, 16 and nine out of 28 patients, respectively, using amplitude, slope and timing of enhancement as parameters. CONCLUSION: Dynamic contrast-enhanced colour-coded MRI of cervix carcinoma has limited value for assessing the extent of tumour spread and tumour staging.     

Efficiently activated carbon fiber derived from grafted novoloid fiber

Graft copolymerization of methyl methacrylate onto novoloid fiber was carried out by the electron beam mutual irradiation method. The characteristics of the grafted fiber were almost the same as those of the original novoloid fiber. The grafted fiber was carbonized and activated to yield an efficiently activated carbon fiber. The yield and the specific surface area of the activated carbon fiber, derived from the grafted novoloid fiber, were much greater than those derived from the original novoloid fiber. This is because grafted poly(methyl methacrylate) decomposes into monomer and gaseous products, forming pores on the surface and inside of the novoloid fiber on heating. © 1993 John Wiley & Sons, Inc.     

Corrosion and strength degradation of Si3N4 and sialons in K2CO3 and K2SO4 melts

Si₃N₄-based ceramics, such as hot isostatically pressed Si₃N₄, hot-pressed Si₃N₄, hot-pressed sialons containing 0, 30, 60 and 100% a phase, were corroded by K₂SO₄ and K₂CO₃ melts at 1150 to 1300 and 925 to 1150° C, respectively. The surface chemical reaction-controlled shrinking core model adequately described the relationship between the weight loss of the specimen and time for the corrosion reactions in both K₂SO₄ and K₂CO₃ melts, and the apparent activation energies were 380 to 608 and 157 to 344 kJ mol^?1, respectively. The corrosion rate in K₂CO₃ melt decreased with increasing content of aluminium and yttrium ions in the specimens, but no systematic relation was observed for the reaction in K₂SO₄ melts. The fracture strength of the specimens corroded by K₂SO₄ and K₂CO₃ melts degraded to 2/3 to 2/5 of the original values up to a 2% weight loss, and then was almost constant up to 30% weight loss.     

Evaluation methods for improving CAL materials

The main objective of the study was to develop systematic methods for improving CAL materials by comparing the five coursewares which were produced by independent authors and related to high school mathematics, science and engineering. Various kinds of evaluation were undertaken before, immediately before, during and immediately after CAL implementation; e.g. evaluators check on the drafts for courseware; evaluators check on the problems encountered in each frame while studying at the terminals; the readiness, pre- and post-tests; an anxiety scale; questionnaires for assessing any difficulties with learning in each chapter and each course; the course test; an image scale, an attitude scale and a line-connecting type of content analysis. Each courseware was evaluated and compared with others on the basis of the data analysis of tests and questionnaires as well as the learning history records, e.g., total learning duration, total number of passed frames, frequency of use of function keys, actual transitive path graph, actual average branch ratio, relative entropy in each frame and the index of educational effectiveness. A number of important evaluation items were selected by factor analysis. Finally an evaluation package instrument for improving CAL courseware were developed.     

Voltage change across the self-coupled semiconductor laser

The results of experimental and theoretical analyses on the voltage changes across the GaAlAs semiconductor laser diodes caused by the onset of optical feedback are described. The dependence of voltage changes on the injection current and on the feedback ratio indicates that the origins of the voltage changes are the photoconduction effect and a reduction of the quasi-Fermi level related to the enhanced stimulated emission. The calculated voltage changes based on the theoretical analyses using the published laser parameters are in good agreement with the experimental ones. The preferable specifications for a laser diode (LD) to exhibit a larger voltage change at the onset of optical feedback are discussed.     

Evaluation of fatigue crack initiation life from a notch

Local strain at the notch-root and its effect on fatigue crack initiation was investigated in four metals by the real-time, fine-grid method. Special attention was focused on local notch-root strain behaviour until crack initiation. From the application of strain hysteresis at the notch root, the maximum strain under loading conditions during each cycle was investigated in detail. One of the main results was that the maximum strain value at the first cycle of the fatigue test coincided with that at crack initiation. Maximum strain defined from the cyclic strain changes at the notch root was proposed as one possible parameter for estimating fatigue crack initiation life. Based on the curvilinear relationship between maximum strain and number of cycles to crack initiation, a new life evaluation method for fatigue crack initiation is proposed. This approach differs fundamentally from the usual fracture mechanics method based on the stress intensity factor.