Formation and removal of hepatic DNA adducts was studied inmale Sprague-Dawley rats following single injections of twohepatocarcinogens, N-hydroxy-2-acetylaminofluorene (N-OH-AAF)and N-hydroxy-4-acetylaminobiphenyl (N-OH-AABP) and a nonhepatocarcinogen,N-hydroxy-2-acetylaminophenanthrene (N-OH-AAP) at 0.5 h, 1.5h, 4 h, 24 h, 9 d and 29 d. Using a previously described 32P-postlabelingassay, maximal DNA binding of these compounds was observed atapproximately 1.5 h, 0.5 h and 24 h, respectively. In additionto the formation of three already known C8- and N2-acetylatedand C8-deacetyiated guanine derivatives and several minor unknownadducts with N-OH-AAF, a set of four new major adducts was alsodetected. These comprised 50% of the total adducts during thefirst 4 h. The three known adducts amounted to 58, 16 and 6%of the 1.5-h value after 24 h, 9 d and 29 d, respectively, whilethe bulk (>84%) of the new major adducts were removed fromthe DNA within 24 h and found only in traces after 9 d. N-OH-AABPformed several unknown minor adducts, in addition to the onemajor C8-deacetylated and two minor C8- and N2-acetylated guaninederivatives; only the C8-deacetylated and N2-acetylated adductswere detected after 29 d. In the case of N-OH-AAP, two majorand several minor adducts were detected, most of which werefound to be deacetylated, and as much as 60% of the adductsmeasured at 24 h were still present after 9 d treatment. Thesedata indicte that certain DNA adducts are repaired rapidly,while others persist for long periods. 相似文献
The aim of this study was to evaluate the utility of added DWI sequences as an adjunct to traditional MR imaging in the evaluation of abnormal placentation in patients with suspicion for placenta accreta spectrum abnormality or morbidly adherent placenta (MAP).
Materials and methods
The study was approved by local ethics committee. The subjects included pregnant women with prenatal MRI performed between July 2013 to July 2015. All imaging was performed on a Philips 1.5T MR scanner using pelvic phased-array coil. Only T2-weighted and diffusion-weighted imaging (DWI) series were compiled for review. Two randomized imaging sets were created: set 1 included T2-weighted series only (T2W); set 2 included T2W with DWI series together (T2W + DWI). Three radiologists, blinded to history and pathology, reviewed the imaging, with 2 weeks of time between the two image sets. Sensitivity, specificity, and overall accuracy for MAP were calculated and compared between T2W only and T2W + DWI reads. Associations between imaging findings and invasion on pathology were tested using the Chi-squared test. Confidence scores, inter-reader agreement, and systematic differences were documented.
Results
A total of 17 pregnant women were included in the study. 8 cases were pathologically diagnosed with MAP. There were no significant differences in the diagnostic accuracy between T2W and T2W + DWI in the diagnosis of MAP in terms of overall accuracy (62.7% for T2W vs. 68.6% for T2W + DWI, p = 0.68), sensitivity (70.8% for T2W vs. 95.8% for T2W + DWI, p = 0.12), and specificity (55.6% for T2W vs. 44.4% for T2W + DWI, p = 0.49). There was no significant difference in the diagnostic confidence between the review of T2W images alone and the T2W + DWI review (mean 7.3 ± 1.8 for T2W vs. 7.5 ± 1.8 for T2W + DWI, p = 0.37).
Conclusion
With the current imaging technique, addition of DWI sequence to the traditional T2W images cannot be shown to significantly increase the accuracy or reader confidence for diagnosis of placenta accreta spectrum abnormality. However, DWI does improve identification of abnormalities in the placental–myometrial interface.
Accurate diagnosis of a wide spectrum of urethral/periurethral pathologies in women remains challenging due to its anatomical location and nonspecific clinical presentations. Magnetic resonance imaging (MRI) has emerged as the modality of choice for diagnosing female urethral and periurethral pathologies due to its multiplanar scanning capability, superior soft tissue differentiation, noninvasive nature, and overall excellent contrast resolution.
Methods
In this narrative review, we describe the use of MRI to visualize the female urethra and periurethral pathologies.
Results
MRI can confidently characterize lesions into cystic or solid, provide a more succinct differential diagnosis, and in some cases provide a specific and accurate diagnosis, enabling surgeons to prepare a roadmap before operative procedure. Moreover, functional MRI can be useful to assess dynamic disorders such as urethral hypermobility.
Conclusions
We provide a comprehensive review of normal MR anatomy of the female urethra, as well as the MR features of practically important urethral and periurethral lesions.
1 A method for the production of highly substituted prostaglandin-bovine serum albumin conjugates has been developed. 2 Antisera to prostaglandins B2 and F2alpha were raised in rabbits immunized with prostaglandin-bovine serum albumin conjugates. 3 The antisera were assessed for specificity and sensitivity by the double antibody radioimmunoassay method and after they were covalently linked to powdered cellulose to form a 'solid-phase' system. 4 Solid phase radioimmunoassays were developed using conventional shaking and in the presence of sucrose which obviates the need for continuous mixing of the incubates. 相似文献