Production of hyperplastic changes in the fore-stomach epithelium of rats by shaking stress

의학과/박사[한글] [영문] Many investigators produced lesions in the fore-stomach of rats by feeding with subnutritional diet. Singer (1913) first produced lesions in the fore-stomach by feeding rats with bread mixed wood sawings. Fibiger(1919) produced also lesions in the fore-stomach by feeding with cockroaches (P. americana) infected with Gongylonema neoplasticum. He claimed to have induced cancer of the fore-stomach of the rats in 53 percent of his experimental animals. But it was found by Passay et al.(1935) that Fibiger's lesion of the fore-stomach was not cancer, but that the lesions only comprised hyperkeratinization and hyperplasia of the squamous epithelium of the fore-stomach together with some papillomatosis. Pappenheimer et al.(1924) also produced the same lesion in the fore-stomach of rats on a rachitic diet which consisted of 95% flour. Hoelzel and DaCosta(1931) produced ulcers in rats on law protein diet. Sharpness(1937) also produced hyperplasia of the fore-stomach in 100% of rats fed on a low protein(casein) diet. These investigators, in producing the lesions, fed the rats with either bread or flour or low protein diet. Fujimaki(1927, 1928) Produced the lesions in rats by feeding vitamin A deficiency diet, but he later reported that vitamin A deficiency was unimportant. The lesions of fore-stomach in rats were also Produced with vitamin B^^2 deficiency by Findlay(1928) and with vitamin B^^l deficiency by Passay et al.(1935) and Dalldorf and Kellogg(1932), Levrat and Lambert(1959) produced gastric ulceration in glandular portion of rat by stimulating the rats with intermittent electric light and at the same time rocking the rats. But they did not find any change in the fare-stomach. In this laboratory, Lee(1964), Moon(1964) and Park(1967) Produced hyperplasia, hyperkeratinization and ulcers in the fore-stomach of rats by shaking the rats with modified method of Levrat and Lambert's experiment. The purpose of this experiment was to try to clarify the descrepancies between the results of Levrat and Lambert and these of park. My results showed that gastric ulceration of the glandular portion of the rat's stomach was not produced by Levrat and Lambert's method. I then investigated the part that diet might play in this descrepancy. The rats were fed on various diets and shaking stress was given to rats, and the fore-stomach change was investigated, The results obtained were different from that of Park(1967). Methods and Results. Apperantly healthy adult male albino rats were used. The rats were on rice diet to which was added various amount of Brewer's yeast or vitamin mixture. The rats were fed on the experimental diet at least 10 days before from the beginning of the experiment. (A) The effect of intermittent photic stimulation and shaking stress on the change of the stomach. The experiment of Levrat and Lambert was repeated by shaking and shining the rats with intermittent electric lamp. The rats were kept in dark room and were subjected to mechanical shaking with frequency of 130-170 Per minute for 23 hours daily and at the same time were stimulated with 100 watt electric lamp which was intermittently off and on. The stress was added for a week then the rats were sacrificed and the stomachs were investigated. There were no definite ulcers of glandular portion big enough to be recognizable macroscpically. Rather there appeared lesions on the fore-stomach. The lesions of the fore-stomach were the same as those shown by the experiments of Lee and Moon etc. (B) The effect of diet on the lesions of stomach produced by shaking stress. The experiment of Park was repeated. Though Park produced lesions of the fore-stomach in more than 50% of the rats subjected to the experiments, in my experiment, the lesions occurred in far less than 50% of the rats subjected to the experiment with the same condition as that of Park,. So the experiments were repeated changing the diet as well as frequency and the period of the shaking. When the Brewer's yeast was decreased and olive oil added instead of cod liver oil to the diet and the frequency of the shaking stress increased from 240 to 260 per minute and the period of shaking stress increased from 3 to 4 hours a day and the period of experiment from 6 to 7 days, then more than 50% of the rats subjected to the experiment, developed the lesions of the fare-stomach. In the next experiment, casein was added to the diet. No lesions of fore-stomach was produced among the rats fed on the diet added casein, while lesions were produced among the rats fed on the diet to which no casein was added. The diet to which vitamin A was added was compared with the diet to which the vitamin was not added. The vitamin A deficiency did not effect the production of the lesions of fore-stomach. Summary The shaking stress was given to the albino rats and the change of gastric mucous membrane was investigated. 1. The experiment of Levrat and Lambert was repeated. No definite change of glandular portion was detected but rather the lesions of fore-stomach were detected. 2. The production of the lesions of fore·stomach of the rats fed on rice diet by shaking stress varied by changing the content of the diet. The production of the lesions was high when the rats fed on diet which contained less Brewer's yeast, and which contained olive oil instead of cad liver oil. No change of fore-stomach was found when the rats were fed a diet which contained cad liver oil and more Brewer's yeast and more protein.restrictio

특성에디 분해법에 의한 Burgers 난류유동장의 수치적 해석

학위논문(박사) - 한국과학기술원 : 기계공학과, 1990.8, [ 13, 145 p. ]Burgers`` Turbulence Model Characteristics of the Karhunen-Loeve expansion of a strongly inhomogeneous random field possessing small viscous length scale in the near wall region and a large outer scale in the interior region have been investigated in relation to the application of the expansion to turbulent flow fields. Monte Carlo simulations of a randomly forced Burgers`` equation with zero velocity boundary conditions generate the random process numerically. The statistical moments of its field on the full domain and in the wall layer are investigated for various Reynolds numbers. The correlation of instantaneous velocity and the covariance of fluctuation velocity are computed to analyze the coherent structure of the entire flow field. The Karhunen-Loeve eigenfunctions and the eigenvalue spectra are computed for three Reynolds numbers, Re=413.5, 1654, and 6616. The eigenfunctions possess thin viscous boundary layers at the wall, and they are independent of the Reynolds number in the core region where the random process is quasihomogeneous. The eigenfunctions and eigenvalues of the Karhunen-Loeve expansion are known to exhibit similarity outside of the viscous wall layers in the sense of Reynolds number independence. It is known that the Karhunen-Loeve expansion of a wall layer of suitable thickness has low-order eigenvalues and eigenfunctions that are also independent of the Reynolds number when expressed in terms of appropriate wall variable. This leads to a generalized law of the wall in which the basis functions of the Karhunen-Loeve expansion and the eigenvalue spectrum are universal, in the sense of asymptotic independence of Reynolds number. Eigenvalue spectra contain much of energy in the first few modes, but they are as broad as ordinary trigonometric power spectra. The rate at which the expansion converges to within 90\% of the total energy decreases with increasing Reynolds number and the expansion of the mean plus the fluctuation convergences more...한국과학기술원 : 기계공학과