Triage of women with equivocal or low-grade cervical cytology results: a meta-analysis of the HPV test positivity rate

Consistent evidence underlines the utility of human papillomavirus (HPV) DNA testing in the management of women with equivocal cervical cytological abnormalities, but not in case of low-grade lesions. We performed a meta-analysis including studies where the high-risk probe of the Hybrid Capture-II is used to triage these two cytological categories. The triage test-positivity rate reflects the colposcopy referral workload.Data were pooled on the HPV test positivity rate in women with atypical squamous cells of undetermined significance (ASCUS/ASC-US) or low-grade squamous intraepithelial lesions (LSIL), derived from different cytological classification systems. The meta-analysis was restricted to studies, published between 1991 and 2007. A random-effect model was applied for meta-analytical pooling and the influence of covariates on the HPV positivity rate was analyzed by meta-regression. The variation by age was assessed within individual studies since age strata were not defined uniformly. On an average, 43% (95% CI: 40–46%) of women with ASCUS/ASC-US were high-risk HPV positive (range 23–74%). In women with LSIL, the pooled positivity rate was 76% (95% CI: 71–81%; range 55–89%). In spite of considerable inter-study heterogeneity, the difference in HPV positivity between the two triage groups was large and highly significant: 32% (95% CI: 27–38%). HPV rates dropped tremendously as age and cutoffs of test positivity increased. Other factors (cytological classification system, country, continent, collection method and year of publication) had no statistically significant impact, except in LSIL triage where HPV positivity was significantly lower in European compared to American studies. Women with LSIL, especially younger women, have high HPV positivity rates suggesting limited utility of reflex HPV triaging these cases. Research is needed to identify more specific methods to triage women with low-grade squamous cervical lesions.     

Spatiotemporal distribution of Fras1/Frem proteins during mouse embryonic development

The Fras1/Frem gene family encodes for structurally similar, developmentally regulated extracellular matrix proteins. Mutations in Fras1, Frem1 and Frem2 have been identified in different classes of mouse bleb mutants, while defects in the human orthologs FRAS1 and FREM2 are causative for Fraser syndrome. The hallmark phenotypic feature of bleb mice is embryonic skin blistering due to dermal-epidermal detachment. The similarity of the phenotypic characteristics among the bleb mouse mutants, together with the fact that Fras1/Frem proteins are co-localized in embryonic epithelial basement membranes, suggest that they operate in a common pathway. Here, we report for the first time the immunofluorescence pattern of Frem3 and provide a comparative analysis of the spatiotemporal localization of all Fras1/Frem proteins during mouse embryonic development. We demonstrate their overall co-localization in embryonic epithelial basement membranes, with emphasis on areas of phenotypic interest such as eyelids, limbs, kidneys, lungs and organs of the gastrointestinal tract and the central nervous system. We further studied collagen VII, impairment of which produces dystrophic epidermolysis bullosa, a postnatal skin blistering disorder. We show that basement membrane levels of collagen VII rise at late embryonic life, concomitant with descending Fras1/Frem immunolabeling.     

Subcellular localization of regulator of G protein signaling RGS7 complex in neurons and transfected cells

The R7 family of regulators of G protein signaling (RGS) is involved in many functions of the nervous system. This family includes RGS6, RGS7, RGS9, and RGS11 gene products and is defined by the presence of the characteristic first found in Disheveled, Egl-10, Pleckstrin (DEP), DEP helical extension (DHEX), Gγ-like, and RGS domains. Herein, we examined the subcellular localization of RGS7, the most broadly expressed R7 member. Our immunofluorescence studies of retinal and dorsal root ganglion neurons showed that RGS7 concentrated at the plasma membrane of cell bodies, in structures resembling lamellipodia or filopodia along the processes, and at the dendritic tips. At the plasma membrane of dorsal root ganglia neurons, RGS7 co-localized with its known binding partners R7 RGS binding protein (R7BP), Gαo, and Gαq. More than 50% of total RGS7-specific immunofluorescence was present in the cytoplasm, primarily within numerous small puncta that did not co-localize with R7BP. No specific RGS7 or R7BP immunoreactivity was detected in the nuclei. In transfected cell lines, ectopic RGS7 had both diffuse cytosolic and punctate localization patterns. RGS7 also localized in centrosomes. Structure-function analysis showed that the punctate localization was mediated by the DEP/DHEX domains, and centrosomal localization was dependent on the DHEX domain.     

A structural basis for the aortic stress-strain relation in uniaxial tension

A constitutive law that includes three analytical expressions was recently proposed to approximate the low, physiologic, and high-stress parts of the aortic stress-strain relation in uniaxial tension, consistent with the biphasic nature of the aortic wall under passive conditions. This consistency, and the fact that previous phenomenological uniaxial laws have only indirectly been related to vessel wall structure, motivates the investigation of the structural basis underlying the newly proposed three-part constitutive law. For this purpose, longitudinally oriented aortic strips were fixed in Karnovsky's solution, while subjected to various pre-selected levels of uniaxial tensile stress. Light microscopy examination disclosed that the elastic lamellae gradually unfolded at low and were almost straight at physiologic and high stresses, while collagen fibers reoriented in the longitudinal axis at low, started uncoiling at physiologic, and straightened massively at high stresses. In the circumferential sections, the elastic lamellae and the circumferentially distributed collagen bundles remained wavy at all levels of longitudinally applied stress. These microstructural changes suggest that elastin becomes load-bearing at low, and collagen at physiologic but mostly at high stresses, so that the first and third parts of the constitutive law are in turn due to the presence of elastin and collagen alone, and the second due to both elastin and collagen. The structural basis of this constitutive law allows physically significant interpretation of its parameters, offering insight into how the aortic microstructure determines the macromechanical response.