The Standard Decompression Schedule was evaluated by the method of bubble formation in agarose gel, the result of which can be summarized as folows:
1) The number of bubbles formed in agarose gel corresponded well with the exposed pressure.
2) The technique of this method was simple and the number of bubbles was accurately counted.
3) Eventually, this method was useful for examining the decompression schedules.
4) It is not always safe to follow the Standard Decmopression Schedule in some pressure conditions.
5) As to the period of time that a person is able to tolerate a high pressure condition, the prescription of the Standard Decompression Schedule is not necessarily correct.
6) The number of bubbles was small by the proper decompression schedule, for example, in the cases of exposure above the 60-meter depth of water.
7) This method can be applied for the prevention of decompression sickness when the agarose gel samples are attached to the workers during the compressed air work.
8) The number of bubbles was inconsistent with the coefficient of body pressure (1. N2 in the body), therefore it is not necessarily safe to rely only on the coefficient of body pressure.
9) To prevent osteonecrosis, the Standard Decompression Schedule is not proper, a deeper first stop and slower ascent being recommended.
Alteration in the cerebrospinal fluid (CSF) circulation was studied in 62 patients with neurosurgical diseases by CT cisternography using a water-soluble contrast medium, metrizamide, and also with radionuclide (169Yb- or 111In-DTPA) cisternography. As a rule, the patterns of both methods were in good agreement. The findings were classified into 3 types and 5 subdivisions.
CT cisternography is useful for sequential observation of the CSF circulation with detailed morphological definition, and radionuclide cisternography is useful for observing the general flow of CSF. Some patients with hydrocephalus showed hypodensity around the ventricle, where migration of metrizamide was observed on CT images after its ventricular reflux. This suggests an increased transependymal resorption of CSF. The mathematical analysis of attenuation coefficients on CT cisternography provided more objective and quantitative data for study of CSF dynamics.
This study was conducted to examine the effect of various dentifrices on the abrasion of acrylic resin and extracted human tooth. The influence of the difference in the hardness of the filament of the toothbrush on the abrasion was also studied, using three kinds of toothbrushes. The specimens (acrylic resin and extracted human tooth) were brushed 3.,000 times by the back and -forth stroke movement using a toothbrushing machine for two hours. The surface irregularities of the specimen were analyzed by the surface analyzer and observed by the scanning electron microscopy before and after the brushing procedure. Moreover, the weight loss of the test specimens of the acrylic resin materials was determined, weighing them by a microbalance before and after brushing.
The abrasiveness of the dentifrices showed a wide range, but the abrasiveness of the toothbrush itself was not observed. All dentifrices except one which did not contain the abrasive materials had abrasive effects on both the acrylic resin and human tooth. There was a high correlation (r=0.96) between the weight loss and the surface irregularities in the case of acrylic resin.