Novel proteins with binding specificity for DNA CTG repeats and RNA CUG repeats: implications for myotonic dystrophy

While an unstable CTG triplet repeat expansion is responsible for myotonic dystrophy, the mechanism whereby this genetic defect induces the disease remains unknown. To detect proteins binding to CTG triplet repeats, we performed bandshift analysis using as probes double- stranded DNA fragments having CTG repeats [ds(CTG)6-10] and single- stranded oligonucleotides having CTG repeats ss(CTG)8 or RNA CUG triplet repeats (CUG)8. The source of protein was nuclear and cytoplasmic extracts of HeLa cells, fibroblasts and myotubes. Proteins binding to the double-stranded DNA repeat [ds(CTG)6-10], were inhibited by nonlabeled ds(CTG)6-10, but not by a non-specific DNA fragment (USF/AD-ML). Another protein binding to ssCTG probe and RNA CUG probe was inhibited by nonlabeled (CTG)8 and (CUG)8. Nonlabeled oligos with different triplet repeat sequences, ss(CAG)8 or ss(CGG)8, did not inhibit binding to the ss(CTG)8 probe. However, when labeled as probes, the (CAG)8 and (CGG)8 bound to proteins distinct from the CTG proteins and binding was inhibited by nonlabeled (CAG)8 or (CGG)8 respectively. The protein binding only to the RNA repeat (CUG)8 was inhibited by nonlabeled (CUG)8 but not by nonlabeled single- or double-stranded CTG repeats. Furthermore, the CUG-BP exhibited no binding to an RNA oligonucleotide of triplet repeats of the same length but having a different sequence, CGG. The CUG binding protein was localized to the cytoplasm, whereas dsDNA binding proteins were localized to the nuclear extract. Thus, several trinucleotide binding proteins exist and their specificity is determined by the triplet sequence. The novel protein, CUG-BP, is particularly interesting since it binds to triplet repeats known to be present in myotonin protein kinase mRNA which is responsible for myotonic dystrophy.      

实时灰阶超声造影和螺旋CT诊断肝肿瘤的比较研究

目的比较实时超声造影和螺旋CT显示肝肿瘤血流信号的特点.方法对29例肝肿瘤(原发性肝癌16例,转移性肝癌2例,血管瘤6例和肝局灶性结节增生5例)分别进行超声造影和CT检查.结果超声造影显示肝恶性肿瘤的整体型、血管瘤的周边型及局灶性结节增生的中央型出现率显著高于其他病变(P<0.01).CT示恶性肿瘤中94.4%(17/18) 动脉期强化、门脉期低密度;血管瘤中83.3%(5/6)呈结节状强化;肝局灶性结节增生动脉期均明显强化.超声造影和CT鉴别肝肿瘤的能力无显著差异.结论超声造影和CT都能敏感地显示不同肝肿瘤的血供特征.     

The role of human papillomavirus type 16/18 genotyping in predicting high‐grade cervical/vaginal intraepithelial neoplasm in women with mildly abnormal Papanicolaou results

BACKGROUND:

The authors compared the predictive value of type 16 and/or 18 human papillomavirus (HPV) versus non‐16/18 HPV types for high‐grade (grade ≥2) cervical neoplasm/vaginal intraepithelial neoplasm and carcinoma (CIN/VAIN2+) in women with mildly abnormal Papanicolaou (Pap) results (ie, atypical squamous cells of undetermined significance [ASCUS] or low‐grade squamous epithelial lesion [LSIL]).

METHODS:

The authors retrospectively selected Pap specimens with HPV testing results obtained from 243 women (155 with ASCUS and 88 with LSIL Pap results) in their Department of Pathology. HPV genotyping was performed using the EasyChip HPV blot assay. The Pap specimens with HPV16/18 and non‐16/18 HPV types were compared with follow‐up biopsy results. Follow‐up duration ranged from 1 month to 58 months (mean, 26 months).

RESULTS:

In total, 58 of 155 specimens (37%) that had ASCUS and 29 of 88 specimens (33%) that had LSIL were positive for HPV16/18. CIN/VAIN2+ biopsies were identified in 43 of 155 women (28%) with ASCUS and in 28 of 88 women (32%) with LSIL. Women with ASCUS and HPV16/18 had a significantly higher rate (43%) of CIN/VAIN2+ than women with ASCUS and non‐16/18 HPV types (19%; P = .003; odds ratio, 3.10; 95% confidence interval, 1.48‐6.53). There was no statistically significant difference in the rate of CIN/VAIN2+ between women who had LSIL and HPV16/18 (45%) and those who had LSIL and non‐16/18 HPV types (29%; P = .16; odds ratio, 1.96; 95% confidence interval, 0.77‐4.97).

CONCLUSIONS:

HPV genotyping for HPV16/18 improved risk assessment for women with ASCUS Pap results and may be used to predict the risk of CIN/VAIN2+ to better guide follow‐up management. Cancer (Cancer Cytopathol) 2013. © 2012 American Cancer Society.     

Image‐guided ThinPrep Papanicolaou tests and cotesting with high‐risk human papillomavirus in women aged 30 years and older in a low‐risk private practice population

BACKGROUND:

Screening for cervical cancer precursors has evolved considerably with the introduction of new technologies to improve the early detection of disease. The objective of this study was to analyze the accuracy and effectiveness of combined screening with cytology and high‐risk human papillomavirus (HR‐HPV) testing in a low‐risk population of women aged ≥30 years.

METHODS:

Consecutive unselected samples from a group of 1871 women aged ≥30 years were screened with image‐guided ThinPrep tests and HR‐HPV tests during a 6‐month period. Histologic follow‐up was reviewed among women with positive HR‐HPV tests.

RESULTS:

A total of 85 (4.5%) women had positive HR‐HPV tests. In 48 HR‐HPV–positive women with follow‐up biopsies, 41 (85%) were found to have histologic abnormalities. Thirty‐three (1.9%) women with cytologically normal Papanicolaou (Pap) tests harbored HR‐HPV, and a cervical intraepithelial neoplasia (CIN) 2+ lesion was detected in 1 (16%) of 6 women with histologic follow‐up. Conversely, 2 (28%) of 7 women with high‐grade intraepithelial lesion on cytology tested negative for HR‐HPV during the same period. A case of serous carcinoma with atypical glandular cells on cytology was also negative for HR‐HPV, as expected.

CONCLUSIONS:

In this low‐risk population of women aged ≥30 years, histology‐confirmed CIN2+ lesions were identified in women with negative cytology and positive HR‐HPV tests, as well as in those with positive cytology and negative HR‐HPV tests. Because both cytology and HPV testing alone missed significant lesions, cotesting with Pap and HR‐HPV in women aged ≥30 years appears to be a reasonable option in a low‐risk population. (Cancer Cytopathol) 2009. © 2009 American Cancer Society.