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The presence of checkpoint mechanisms which are able to recognize damaged chromatin and thereafter to prevent exit from metaphase I has been investigated in giant mouse oocytes produced by fusion of a normal metaphase I oocyte with an equivalent oocyte with damaged chromatin. The presence of damaged chromatin did not prevent the onset of anaphase I in both sets of chromatin in the fused cells. Interestingly, fused or unfused cells containing only damaged chromatin failed to enter anaphase and persisted instead in a metaphase-like state. These results demonstrate the fragility of checkpoint controls in mammalian female germ cells.   相似文献   
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Axel  L; Summers  RM; Kressel  HY; Charles  C 《Radiology》1986,160(3):795-801
Respiratory and other regular motions during two-dimensional Fourier transform magnetic resonance imaging produce image artifacts consisting of local blurring and more or less regularly spaced "ghost" images propagating along the direction of the phase-encoding magnetic field gradient. The patterns of these ghost artifacts can be understood in terms of the technique of image production and basic properties of the discrete Fourier transform. This understanding permits, without respiratory gating, production of images of improved quality in body regions in which there is significant respiratory motion. In particular, the ghosts can be maximally separated from the primary image by choosing intervals between phase-encoding gradient pulse increments that are equal to one-half the respiratory period; they can be minimally separated by choosing an interval equal to the respiratory period. Increasing the number of signal averages between each phase-encoding increment decreases the intensity of the ghosts.  相似文献   
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Advances in liposome technology over the last decade has seen the development of stealth liposomes for drug delivery and cationic liposomes for gene delivery. Many of these liposome formulations are now in clinical trials for the treatment of a variety of malignancies. Whilst some clinical efficacy has been demonstrated, the goal of specific tumor targeting is yet to be attained. For this reason, antibodies have been attached to the surface of liposomes to produce immunoliposomes. These liposomes have shown preferential binding to specific tumor cells in animal models. The construction of the immunoliposome, and in particular the optimal method of antibody coupling to its surface is, however, yet to be determined. Despite these difficulties, immunoliposomes have demonstrated anti-tumor properties, both in vitro and in vivo, and show great promise as targeted delivery vehicles for the treatment of cancer.  相似文献   
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This review correlates the imaging findings and histological appearances seen in chordomas in a series of patients presenting at our institution, together with a published literature review. A parallel presentation of photographs of imaging findings and microscopic histological findings is made, with the aim being to enhance recognition of this uncommon but clinically significant entity.  相似文献   
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Could epithelial ovarian cancer be associated with chlamydial infection?   总被引:1,自引:0,他引:1  
PURPOSE OF INVESTIGATION: Epithelial ovarian cancer (EOC) is the leading cause of death from gynaecological malignancy in the UK. The pathogenesis of this disease is poorly understood. Our hypothesis was that chlamydial infection might play a role in the pathogenesis of EOC. METHODS: 122 serum samples of patients undergoing surgery for benign or malignant gynaecological conditions were analysed. There was a total of 41 patients with EOC (33.6%), 27 with benign cystadenomas (22.1%) and 54 with normal ovaries (44.3%). RESULTS: There was a higher incidence of IgA seropositivity and lower incidence of IgG seropositivity in the EOC group compared with the other groups; however, this was not statistically significant. There was no statistical difference in the serum IgM antibodies to chlamydia in the three different groups. CONCLUSION: Although chronic infection and persistent inflammation may contribute to the pathogenesis of EOC, and chlamydia is a common genital tract pathogen, our study did not find an association between chlamydia and EOC.  相似文献   
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