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51.
Effect of ultrasound exposure on sonicated microbubbles stability   总被引:3,自引:0,他引:3  
The study of intlavenous myocedal coneest echocedo~ (IVMCE) is a hot topic in the Pursuit ofcoronap healt disease, and much achievement has beenmade in ash ultheound etwpment development and cont. .[if ~t agent improvement. Most colltrsst opllts such asMiunex, Ophson etc. are pIDduced by sonication, andcan be used as echogenic bacers of blood flow in WMCE.SOme studies have suggested, however, that the ndcrobubbles exposed to ultrasound are Open to mpture[']. Ihan effort to detendne the o…  相似文献   
52.
目的与方法造影剂微泡浓度、大小是影响心肌声学显影最重要因素。本研究采用2×2×4析因分析法分析不同超声照射条件对造影剂微泡浓度及直径的影响,即声波频率、能量以及照射时间对微泡浓度、大小的单独及交互作用。为临床行静脉心肌声学造影检查时选择适宜的超声照射条件提供参考。结果能量越大、照射时间越长,微泡破坏越多,平均直径越小:照射频率对微泡浓度影响不大,但影响微泡大小,频率越高,微泡越小。结论为减少超声照射对微泡的破坏,提高心肌声学造影效果,应尽可能选用低能量、低频率超声波,并减少不必要的照射时间。  相似文献   
53.
At the present time multiple chemical sensitivities (MCS) is generally acknowledged to be a poorly understood clinical syndrome which is exhibited by individuals exposed to low levels of exposure to environmental agents that the general population tolerate quite well. A wide range of individual symptoms (typically multiple and related to neurologic, endocrine/metabolic, and immunological, often occurring simultaneously) are displayed by MCS patients. Questions concerning whether or not MCS is a real clinical condition, a form of psychiatric illness or a combination of both remain to be unambiguously clarified.  相似文献   
54.
Prenatal administration of high doses of tricyclic antidepressants have been reported to produce teratogenic and behavioral effects in rat offspring. In the present work, behavioral abnormalities are described in offspring of rats treated with therapeutic doses of chlorimipramine (CIM) during pregnancy (CIM-P), lactation (CIM-L) and during the whole pregnancy-lactation period (CIM-PL). CIM-P treatment did not produce teratogenic effects, did not affect number or body weight of pups at birth and did not induce neonatal mortality. At 2 months of age, the CIM-P males showed a significant increase in digging and grooming (familiar environment test), a decrease in exploration (novel environment test) and a decrease in active social interactions (social behavior test). Females were more resistant than males to the prenatal CIM treatment. The results suggest increased emotionality in CIM-P pups. Some behavioral abnormalities were also observed in the tests performed at 4 months of age. CIM-L treatment had minor effects on litter behavior. CIM-PL treatment potentiated the effects of the CIM-P treatment. In the CIM-PL males, impairment of exploration of a novel environment still remained in the tests performed at 4 months of age. It is speculated that when prenatal brain development is altered by CIM, further postnatal treatment may impair compensatory processes occurring in early postnatal life.  相似文献   
55.
Groups of adult male Sprague-Dawley rats were treated i.p. with 0, 0.3 and 0.5 mmole bromobenzene (BB)/kg per day in corn oil, 5 days a week for 4 weeks. Thereafter, one half of each of these groups was treated i. p. with a single acute toxic dose of 2.5 mmole BB/kg. Urines were then collected for 24 h and the animals were then sacrificed. The hepatotoxicity induced by an acute dose of BB was significantly reduced due to prior subchronic exposure to BB at 0.5 mmol/kg, but not so at 0.3 mmol/kg. These data indicate a potential tolerance against acute hepatotoxicity of BB due to prior subchronic exposure. A significant increase in the urinary excretion of thioethers or mercapturic acids of BB combined with a significant increase in the urinary level ofp-bromocatechol due to prior subchronic treatment with 0.5 mmol BB/kg relative to those due to acute treatment alone was observed. Thus enhanced bromobenzene metabolism could partly explain such potential tolerance against its acute hepatotoxicity. Such protection may also be related to certain cellular events which might occur subsequent to metabolic activation of BB.  相似文献   
56.
Summary When adequate human observations are not or scarcely available, permissible levels for occupational exposure have to be extrapolated from animal experiments. Taking into account experimental conditions, e. g., duration of exposure ( 3 months), animal species, knowledge of no- (adverse-) effect level or minim al-(adverse-) level, presence of data on human observations, the authors worked out a procedure for extrapolation. This procedure should only be applied for systemic non-carcinogenic effects. The proposed procedure is to be regarded as tentative and as suggestion for international discussion.The evaluation starts with a safety factor = 10 for extrapolation from dose/kg b. w. in long-term animal experiments to exposure of adult workers (40 h/wk); this factor corresponds to a safety factor = 3–10 for extrapolation from doses presented as concentrations in air. If long-term experimental exposure is 24 h daily, the safety factor can be lowered to the minimum value of 1. If only short-term exposure studies are available, the safety factor may have to be increased to a maximum of 400.  相似文献   
57.
Although 1-bromopropane has been used in chemical and electronic industries as an alternative to ozone layer-depleting solvents, its toxicity on female reproductive organs has not been fully elucidated. The aim of this experiment was to determine the effect of 1-bromopropane on female reproductive function in rats. Forty female Wistar rats were divided into four equal groups. Each group was exposed daily to 0, 200, 400, or 800 ppm of 1-bromopropane for eight h a day. After exposure for 7 weeks, all rats in the 800-ppm group became seriously ill and were sacrificed during the 8th week. The other dose groups were exposed for 12 weeks. In the 800-ppm group, but not in the other two exposed groups, body weight was significantly less than the control at each time point from 2 to 7 weeks after the beginning of exposure. Tests of vaginal smears showed a significant increase in the number of irregular estrous cycles with extended diestrus in the 400- and 800-ppm groups. Histopathological examination of the ovary showed a significant dose-dependent reduction of the number of normal antral follicles and a decrease in the number of normal growing follicles in the 400-ppm group. No significant change was found in plasma concentrations of LH or FSH in any group when compared with the control. Our results indicate that 1-bromopropane can induce a dose-dependent ovarian dysfunction in nonpregnant female rats associated with disruption in follicular growth process.  相似文献   
58.
We investigated the systemic immunotoxic potential of respiratory exposure to diesel exhaust particles (DEP) in this study. Female B6C3F1 mice (approximately 8 weeks old) were exposed to increasing concentrations of DEP intratracheally, 3 times every two weeks, and sacrificed 2 or 4 weeks after the first exposure. The systemic toxicity and immune status in mice were evaluated. Mice exposed to DEP (1 to 15 mg/kg) showed no significant changes in body, spleen, or liver weights. Lung weights were increased in the mice exposed to 15 mg/kg DEP for 2 or 4 weeks. Except for a decreased platelet count, no significant alterations occurred in hematological parameters following DEP exposure. The number of splenic anti-sheep red blood cell (sRBC) IgM antibody-forming cells (AFC) decreased following DEP exposure for 2 weeks. This effect was less severe following 4 weeks of exposure and was only evident in the high dose group. Exposure to DEP also resulted in a significant decrease in the absolute numbers and the percentages of total spleen cells for total, CD4(+), and CD8(+) T cells, while the numbers of B cells and total nucleated cells in spleen were not significantly changed. The proliferative response of splenocytes to the T-cell mitogen, concanavalin A (ConA), as well as their production of IL-2 and IFN-gamma, was decreased dose-dependently following exposure of mice to DEP for 2 weeks, whereas proliferation was not changed in response to anti-CD3 monoclonal antibody. In summary, short-term respiratory exposure of mice to DEP resulted in systemic immunosuppression with evidence of T cell-mediated and possibly macrophage-mediated mechanisms.  相似文献   
59.
We performed an in vitro study in order to determine possible triggers of hair cell regeneration in the chick basilar papilla following degeneration. We compared the response of sensory epithelium damaged by collagenase treatment with that damaged by acoustic trauma. The former exhibited no proliferative activity, but the latter did. The basilar papillae damaged by acoustic trauma could have proliferating activity in medium containing fetal bovine serum (FBS) or epidermal growth factor (EGF) but not in the medium without FBS or EGF. These findings indicate that regeneration of basilar papillae depends on the manner of cell death and that FBS or EGF is required for regeneration.  相似文献   
60.
【目的】 研究妊娠期接受磁共振 (magneticresonanceimaging ,MRI)复合磁场照射对子代大鼠不同发育期脑部丝裂原活化蛋白激酶 (mitogenactivatedproteinkinase ,MAPK) /细胞外信号调节蛋白激酶 (extracellularsignalregulatedproteinkinase ,ERK )表达的影响。  【方法】 SD孕鼠妊娠第 12~ 18d给予 0 .3 5TMRI磁场照射 ,雌性子鼠1、2、5月龄时进行大脑切片免疫组化SP方法染色 ,并用图像分析仪进行半定量分析。 【结果】 MAPK/ERK免疫反应在大鼠脑切片上广泛表达 ;随着年龄增长 ,未发现其表达的变化 ;在各年龄段子鼠照射组和对照组间MAPK/ERK的免疫反应表达差异均无显著性 (P >0 .0 5 )。 【结论】 妊娠期MRI磁场照射后并未引起子代大鼠MAPK/ERK免疫反应表达的异常  相似文献   
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