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Isolation properties of antivibration mounts were tested with models of the machinery casing and the ship-like structure. The mobilities of the machinery base plate and foundation bed plate of those models were found to be approximated to rigid masses at low frequencies and infinite plates for higher frequencies compared with the first local plate resonance.Using these results and regarding resilient mount as massless spring, isolation properties of the soft and hard resilient mounts and the reduction method of the input vibration power to the ship structure were investigated.In addition, a new type of isolation system in which a damping plate was inserted between the upper and the lower resilient mounts was devised and its superior vibration isolation effect was verified experimentally with the above mentioned models.

An experiment was carried out to determine the protective effect of orotic acid (uracil-4-carboxylic acid) against X-rays. Orotic acid in dose of 0.05, 0.1, 1.0, 1.7 and 10 mg per mouse was given intraperitoneally to mice before or after a single dose whole-body Xirradiation of 700 r or 550 r, after which the 30-day survival rate was observed. As a result it was concluded that it would be difficult to state that orotic acid has a protective effect against X-irradiation. It may be added that even if a protective effect exists it would be slight.

The effect of Aclacinon (ACR) on the X-ray response of the radio-resistant RC-355 cells is investigated. It has been shown that both pre- and posttreatments are effective in enhancing the radiation-induced cell killing. No difference is observed in the effect of the posttreatments with ACR at the concentrations between 0.1 and 0.2μg/ml, while the effect of the pretreatment is revealed to be the concentration-dependent.

A servomechanized system for the exposure of small laboratory animals to the vapor of organic solvents was previously described (Koizumi and Ikeda 1981); as a basic performance, the system was able to generate the organic solvent vapors at any constant concentrations in a range of i0 to i000 ppm with a coefficient of variation (CV) of less than 10%. Succeedingly, efforts were made to improve the function of the system to be able to generate the vapor at the concentration of below i0 ppm and also over i000 ppm so that the system can simulate the exposures of the inhabitants near the factory (Verbeck and Scheffers 1980) as well as the cases of thinner/glue sniffers (Knox and Nelson 1966; Suzuki et al. 1974). The achievements will be reported in the present communication.

Eighteen patients with postinfarction left ventricular aneurysms (LVAs) were examined with Indium-111-labeled autologous platelet scintigraphy to identify intracardiac thrombi and to investigate the effect of antithrombotic agents on thrombogenesity within their LVAs. Left ventriculography (LVG), and two-dimensional echocardiography were also carried out to assess the diagnostic ability of the platelet imaging. Indium-111-platelet scintigraphy for the detection of LVA mural thrombi had a sensitivity of 60% and a specificity of 100%. Four of six patients with false-negative scintigraphic studies had been under antiplatelet therapy. Eight of the nine patients who had showed active platelet deposition on initial examination had not received antiplatelet therapy. Thereafter, five of these nine were treated with tichlopidine (300 mg/day) for 29.8 +/- 5.0 days. On the second platelet study, two had resolution and the other three had interruption of intra-aneurysmal deposition, which remained positive. In only one patient of the three, the third platelet study was performed after warfarin therapy. It took two weeks after beginning the therapy to completely interrupt platelet deposition within the LVA in this patient. ECG gated radionuclide ventriculography and Thallium-201-myocardial scintigraphy were also performed to assess left ventricular wall motion of left ventricular ejection fraction (LVEF) and myocardial blood perfusion. Thallium-201-SPECT showed apical or anteroapical perfusion defects and the radionuclide ventriculography correctly identified all 18 apical and anteroseptal aneurysms which were confirmed by LVG methods. The comparison between the thrombus positive group and the thrombus negative group was carried out on both the LVEF and the period from the last myocardial infarction to the initial platelet scanning study. There were no statistical differences in the LVEF and the interval (34.5 +/- 12.5% vs 37.3 +/- 14.6%, 39.6 +/- 52.6 days vs 89.6 +/- 108.3 days) between the two groups. These results suggest that Indium-111-labeled platelet scintigraphy can be a reliable method for the identification of active left ventricular mural thrombi and a practical method of judging antiplatelet and anticoagulant therapy.

In order to quantify the size of the infarcted myocardium, two kinds of data processing techniques were applied to single photon emission computed tomography (SPECT) with thallium-201 and its clinical reliability was evaluated by comparing it with the infarct sizing procedure with the serial serum creatine kinase-MB measurements in 14 patients with acute myocardial infarction. After maximum-count circumferential profile analysis, short axis images were reformatted into an unfolded surface map and a bull's eye view map. The SPECT-determined infarct size was defined as the area or the percentage of hypoperfused myocardium of which the profile count was less than the mean minus 2SD derived from 8 normal subjects. The infarct area was calculated from the number of pixels with an abnormal count and expressed in an unfolded surface map. The percentage was calculated from the number of abnormal profile points and displayed in a bull's eye view map. A high linear correlation was observed between the enzymatically determined infarct size and the infarct area or the percentage (r = .947, r = .872, respectively), despite underestimations in 2 patients with accompanying right ventricular infarction and overestimations in 2 patients with prior anterior infarction. Moreover, a close negative correlation was found between the left ventricular ejection fraction and the infarct area or the percentage (r = .836, r = .821, respectively). Thus, the semiautomatic techniques for processing thallium-201 SPECT images might contribute to the quantitative estimation and display of infarcted myocardium and have high clinical reliability.

MORITA, K. Sulfhydryl Contents of the Radioresistant HeLa Cells and Their Cross Resistance to Nitrogen Mustard. Radiat. Res. 56, 405-410 (1973). The mechanisms of acquired radioresistance were investigated in the previously established radioresistant HeLa strains by successive treatments with x-irradiation. The amount of nonprotein SH, protein SH and total SH in the radioresistant strains were found to be higher than in the original strain. Radioresistance of these strains did not correlate with their nonprotein SH, but did correlate well with total SH content. The radioresistant HeLa cells were also found to be cross-resistant to nitrogen mustard. However, no strict parallelism in the degree of resistance between x-ray and nitrogen mustard was found.