Hybrid capture 2 and cobas® 4800: Comparison of performance of two clinically validated tests for human papillomavirus primary screening of cervical cancer.

OBJECTIVE: To compare, in a primary human papillomavirus screening setting, two different validated human papillomavirus tests, considering their analytical and clinical screening performances. METHODS: In Tuscany, a human papillomavirus screening program was implemented in 2013. Hybrid capture 2 (Qiagen) was used for testing until May 2016, when it was replaced by the cobas® 4800 human papillomavirus test (Cobas; Roche). We evaluated the performance of Hybrid capture 2 and Cobas on: the same screening population in two different periods (before and after changing to Cobas); the same Hybrid capture 2-positive consecutive samples. Discordant samples (Hybrid capture 2-positive/Cobas negative) were typed on the L1 gene (reverse line blot, AB Analitica) and E6/E7 genes (BD Onclarity assay). RESULTS: In the considered time period (n = 37,775), human papillomavirus positivity was 9.8% and 7.4%, respectively, for Hybrid capture 2 and Cobas (p < 0.0001). At immediate colposcopy, the cervical intraepithelial neoplasia, grade 2 positive predictive value was, respectively, 23.8% and 34% (p < 0.001). At one-year recall, human papillomavirus persistence was, respectively, 40.6% and 62.2% (p < 0.0001). Of Hybrid capture 2-positive re-tested samples (n = 620), 32.4% were Cobas negative. Of discordant samples typed on L1, 7% were positive for the 12 high-risk human papillomavirus. Of the samples found to be negative for the 12 high-risk human papillomavirus types on L1, 14.5% were positive on E6/E7 typing. Among the discordant samples, the only two cervical intraepithelial neoplasia (CIN) grade 3 lesions were non-high-risk human papillomavirus positive on both L1 and E6/E7 typing. CONCLUSION: At baseline, Hybrid capture 2 showed greater human papillomavirus positivity and a lower CIN2+ positive predictive value than Cobas, which was more specific than Hybrid capture 2 in detection of high-risk human papillomavirus: 80% of discordant samples were confirmed as high-risk human papillomavirus negative. This higher analytical specificity determined the non-identification of two CIN3 lesions.

AFM for diagnosis of nanocrystallization of steels in hardening processes.

INTRODUCTION: The aim of this study is to investigate the nanocrystallization of steels caused by the transformation from the austenitic to the martensitic phase induced by a severe plastic deformation (SPD) treatment. In this framework, we applied an air blast shot peening treatment, which is a simple protocol widely used for industrial purposes. METHODS: AISI 286 and AISI 316 specimens were peened for different times and polished using diamond pastes in order to remove corrugations higher than 1 mum. The characterization of the steel surfaces was performed by atomic force microscopy (AFM) operating in contact mode. Additional EDXD measurements were performed to confirm the phase transition. RESULTS AND DISCUSSION: An AFM-based characterization at nanometric level of the steel surfaces is provided. When the peening exceeds a threshold time that, as expected, depends on the steel composition, a uniform nanostructuration is detected. It is well known that such rearrangement is associated to the growth of a martensitic phase. To date, AFM has been employed in this field only for few applications and to solve specific problems. On the other hand, our results demonstrate that this is a useful technique for the characterization of hardened surfaces, especially when non-destructive sample preparation treatments are required. Moreover, we show that AFM can be a useful tool also for in situ industrial diagnostics of metallic parts.

Roughness of the plasma membrane as an independent morphological parameter to study RBCs: a quantitative atomic force microscopy investigation.

A novel approach to the study of RBCs based on the collection of three-dimensional high-resolution AFM images and on the measure of the surface roughness of their plasma membrane is presented. The dependence of the roughness from several parameters of the imaging was investigated and a general rule for a trustful analysis and comparison has been suggested. The roughness of RBCs is a morphology-related parameter which has been shown to be characteristic of the single cells composing a sample, but independent of the overall geometric shape (discocyte or spherocyte) of the erythrocytes, thus providing extra-information with respect to a conventional morphology study. The use of the average roughness value as a label of a whole sample was tested on different kinds of samples. Analyzed data revealed that the quantitative roughness value does not change after treatment of RBCs with various commonly used fixation and staining methods while a drastic decrease occurs when studying cells with membrane-skeletal alteration both naturally occurring or artificially induced by chemical treatments. The present method provides a quantitative and powerful tool for a novel approach to the study of erythrocytes structure through an ultrastructural morphological analysis with the potential to give information, in a non-invasive way, on the RBCs function.

An AFM investigation of oligonucleotides anchored on unoxidized crystalline silicon surfaces.

Carboxylic terminated monolayers have been covalently attached on phosphorous doped crystalline (100) silicon surfaces using a cathodic electro grafting technique. The functionalization concentration and efficiency have been evaluated with different techniques. In particular, topographic images, performed with an atomic force microscope, were used to optimize the protocol in order to obtain a surface whose characteristics of uniformity and reproducibility are ideal for a bio-electronic device. Phase lag images of the functionalized surfaces were also performed, and show non-topographic structures that have been interpreted as areas of different molecule self-orientation. Poly-thymine oligonucleotides have been anchored on such a surface to form a nano-biosensing device capable to react selectively with a specific target molecule, a poly-adenine oligonucleotide. AFM images of high density (approximately 3x10(12) mol/cm2) single strand and double strand covered samples show toroidal shaped structures formed by the self-assembly of the oligonucleotides on the silicon surface.

AFM characterization of solid-supported lipid multilayers prepared by spin-coating.

Lipids are the principal components of biologically relevant structures as cellular membranes. They have been the subject of many studies due to their biological relevance and their potential applications. Different techniques, such as Langmuir-Blodgett and vesicle-fusion deposition, are available to deposit ordered lipid films on etched surfaces. Recently, a new technique of lipid film deposition has been proposed in which stacks of a small and well-controlled number of bilayers are prepared on a suitable substrate using a spin-coater. We studied the morphological properties of multi-layers made of cationic and neutral lipids (DOTAP and DOPC) and mixtures of them using dynamic mode atomic force microscopy (AFM). After adapting and optimizing, the spin-coating technique to deposit lipids on a chemically etched Silicon (1,0,0) substrate, a morphological nanometer-scale characterization of the aforementioned samples has been provided. The AFM study showed that an initial layer of ordered vesicles is formed and, afterward, depending on details of the spin-coating preparation protocol and to the dimension of the silicon substrate, vesicle fusion and structural rearrangements of the lipid layers may occur. The present data disclose the possibility to control the lipid's structures by acting on spin-coating parameters with promising perspectives for novel applications of lipid films.