Shear-Induced Anisotropy in Rough Elastomer Contact.

True contact between randomly rough solids consists of myriad individual microjunctions. While their total area controls the adhesive friction force of the interface, other macroscopic features, including viscoelastic friction, wear, stiffness, and electric resistance, also strongly depend on the size and shape of individual microjunctions. We show that, in rough elastomer contacts, the shape of microjunctions significantly varies as a function of the shear force applied to the interface. This process leads to a growth of anisotropy of the overall contact interface, which saturates in the macroscopic sliding regime. We show that smooth sphere-plane contacts have the same shear-induced anisotropic behavior as individual microjunctions, with a common scaling law over 4 orders of magnitude in the initial area. We discuss the physical origin of the observations in light of a fracture-based adhesive contact mechanics model, described in the companion article, which captures the smooth sphere-plane measurements. Our results shed light on a generic, overlooked source of anisotropy in rough elastic contacts, not taken into account in current rough contact mechanics models.

Shear-induced contact area anisotropy explained by a fracture mechanics model.

This paper gives a theoretical analysis for the fundamental problem of anisotropy induced by shear forces on an adhesive contact, discussing the experimental data of the companion Letter. We present a fracture mechanics model where two phenomenological mode-mixity functions are introduced to describe the weak coupling between modes I and II or I and III, which changes the effective toughness of the interface. The mode-mixity functions have been interpolated using the data of a single experiment and then used to predict the behavior of the whole set of experimental observations. The model extends an idea by Johnson and Greenwood, to solve purely mode I problems of adhesion in the presence of a nonaxisymmetric Hertzian geometry, to the case of elliptical contacts sheared along their major or minor axis. Equality between the stress intensity factors and their critical values is imposed solely at the major and minor axes. We successfully validate our model against experimental data. The model predicts that the punch geometry will affect both the shape and the overall decay of the sheared contact area.

Evolution of real contact area under shear and the value of static friction of soft materials.

The frictional properties of a rough contact interface are controlled by its area of real contact, the dynamical variations of which underlie our modern understanding of the ubiquitous rate-and-state friction law. In particular, the real contact area is proportional to the normal load, slowly increases at rest through aging, and drops at slip inception. Here, through direct measurements on various contacts involving elastomers or human fingertips, we show that the real contact area also decreases under shear, with reductions as large as 30[Formula: see text], starting well before macroscopic sliding. All data are captured by a single reduction law enabling excellent predictions of the static friction force. In elastomers, the area-reduction rate of individual contacts obeys a scaling law valid from micrometer-sized junctions in rough contacts to millimeter-sized smooth sphere/plane contacts. For the class of soft materials used here, our results should motivate first-order improvements of current contact mechanics models and prompt reinterpretation of the rate-and-state parameters.

Clinical validation of Anyplex™ II HPV HR Detection according to the guidelines for HPV test requirements for cervical cancer screening.

BACKGROUND: Anyplex™ II HPV HR Detection (Seegene, Seoul, Korea) is a multiplex real-time PCR using tagging oligonucleotide cleavage and extension (TOCE) technology for simultaneous detection and genotyping of 14 high-risk (HR) HPV types, including HPV16 and HPV18. OBJECTIVES: To evaluate whether the clinical performance and reproducibility of Anyplex™ II HPV HR Detection meet the international consensus guidelines for HPV test requirements for cervical cancer screening [1]. STUDY DESIGN: The clinical performance of Anyplex™ II HPV HR Detection for detecting cervical intraepithelial neoplasia grade 2 or worse (CIN2+) was determined relative to that of the reference assay, i.e., HR HPV GP5+/6+-PCR-EIA, by analysis of a total of 879 cervical liquid based cytology (LBC) specimens from a screening population, of which 60 were from women with CIN2+. The intra-laboratory reproducibility and inter-laboratory agreement were determined on 509 LBC samples, of which 172 were positive by the reference assay. RESULTS: Anyplex™ II HPV HR Detection showed a clinical sensitivity for CIN2+ of 98.3% (59/60; 95% CI: 89.1-99.8) and a clinical specificity for CIN2+ of 93.6% (764/816; 95% CI: 89.8-96.1). The clinical sensitivity and specificity were non-inferior to those of HR HPV GP5+/6+-PCR-EIA (non-inferiority score test: P=0.005 and P=0.023, respectively). Both intra-laboratory reproducibility (96.8%; 95% CI: 95.3-98.1; kappa value of 0.93) and inter-laboratory agreement (96.0%; 95% CI: 94.3-97.4; kappa value of 0.91) were high. CONCLUSIONS: Anyplex™ II HPV HR Detection performs clinically non-inferior to HR HPV GP5+/6+-PCR-EIA. Anyplex™ II HPV HR Detection complies with international consensus validation metrics for HPV DNA tests for cervical cancer screening [1].

Updating the PGMY primers and probes for improved detection of HPV68a: validation of version 2 of the PGMY-CHUV assay.

HPV68a is not efficiently detected by PCR with the PGMY primers. Version 2 of the PGMY-CHUV assay (PGv2) was developed from version 1 (PGv1) to evaluate HPV68-discordant results with the Anyplex II HPV28 assay. We now report that PGv2 is significantly more sensitive than PGv1 for HPV68a and as sensitive and specific for the other HPV genotypes during a 1-year prospective validation (n = 714 samples).

Comparison of Seegene Anyplex II HPV28 with the PGMY-CHUV assay for human papillomavirus genotyping.

The Anyplex II HPV28 (H28; Seegene) is a new semiquantitative real-time multiplex PCR assay for screening and genotyping 28 human papillomaviruses (HPV) in only 2 reaction wells. H28 was compared to the PGMY-CHUV assay (PG) with 309 archival DNA samples from cervical smears collected over 8 years in our laboratory. H28 and PG were fully concordant at the genotypic level on 228 (73.8%) out of 309 samples: 27 HPV negative and 201 HPV positive. The 201 fully concordant positive samples corresponded to single infections (n = 145) and to multiple infections (2 genotypes, n = 38; 3 to 5 genotypes, n = 18). The remaining 81 samples (26.2%) were either partially concordant (n = 64, 20.7%) or fully discordant (n = 17, 5.5%). While genotype-specific agreement was nearly perfect (κ = 0.877), HPV51 was significantly less well detected by H28 and the converse was observed for HPV40, -42, -54, and -68. Sequencing of PG amplicons confirmed HPV51 discordants and suggested the involvement of a possibly local HPV51 subtype. Mismatches in the PGMY09 primers to HPV68a explained most of the HPV68 discordants, confirming the specificity of H28 toward HPV68. With PG as a reference, the sensitivity and specificity of H28 were 93.4% and 99.0%, respectively. Considering H28 as a reference, the sensitivity and specificity of PG were 83.8% and 99.6%, respectively. H28 is a very sensitive and specific HPV genotyping assay suitable for research and clinical use as an adjunct to a clinically validated test. H28 semiquantitative readout ought to be evaluated for primary cervical cancer screening.

[An update on hepatitis E]. / Mise à jour sur l'hépatite E.

The hepatitis E virus (HEV) is an RNA virus transmitted via the fecal-oral route or through uncooked animal meat products. Of the 4 known genotypes, genotype 3 is responsible for autochthonous infections in industrialized countries, with a seroprevalence in Switzerland estimated as high as 22%. The majority of infections is asymptomatic but a minority of patients, notably men over 50 or with underlying liver disease, can present with severe acute hepatitis. Chronic hepatitis E with HEV of genotype 3 has been observed in immunosuppressed patients, mostly transplant recipients. Serology is not sufficiently sensitive, especially in immunosuppressed patients, making PCR identification the preferred test for diagnosing active infection. Ribavirin or interferon-alpha can be used to treat chronic hepatitis E if reduction of immunosuppressive treatment does not result in viral elimination.

Validation of a low-cost human papillomavirus genotyping assay based on PGMY PCR and reverse blotting hybridization with reusable membranes.

The genotyping of human papillomaviruses (HPV) is essential for the surveillance of HPV vaccines. We describe and validate a low-cost PGMY-based PCR assay (PGMY-CHUV) for the genotyping of 31 HPV by reverse blotting hybridization (RBH). Genotype-specific detection limits were 50 to 500 genome equivalents per reaction. RBH was 100% specific and 98.61% sensitive using DNA sequencing as the gold standard (n = 1,024 samples). PGMY-CHUV was compared to the validated and commercially available linear array (Roche) on 200 samples. Both assays identified the same positive (n = 182) and negative samples (n = 18). Seventy-six percent of the positives were fully concordant after restricting the comparison to the 28 genotypes shared by both assays. At the genotypic level, agreement was 83% (285/344 genotype-sample combinations; κ of 0.987 for single infections and 0.853 for multiple infections). Fifty-seven of the 59 discordant cases were associated with multiple infections and with the weakest genotypes within each sample (P < 0.0001). PGMY-CHUV was significantly more sensitive for HPV56 (P = 0.0026) and could unambiguously identify HPV52 in mixed infections. PGMY-CHUV was reproducible on repeat testing (n = 275 samples; 392 genotype-sample combinations; κ of 0.933) involving different reagents lots and different technicians. Discordant results (n = 47) were significantly associated with the weakest genotypes in samples with multiple infections (P < 0.0001). Successful participation in proficiency testing also supported the robustness of this assay. The PGMY-CHUV reagent costs were estimated at $2.40 per sample using the least expensive yet proficient genotyping algorithm that also included quality control. This assay may be used in low-resource laboratories that have sufficient manpower and PCR expertise.

[A primer on the management of antiviral resistance in chronic hepatitis B]. / Prévention et prise en charge de la résistance antivirale dans l'hépatite B chronique.

Treatment options for chronic hepatitis B have significantly expanded over the last decade. Six nucleoside or nucleotide analogs (NA) with activity against the hepatitis B virus are currently available. Prolonged NA treatment is required in many cases to maintain viral suppression, with an inherent risk of the development of antiviral resistance. The purpose of this concise review is to provide an introduction to the prevention, diagnosis and management of antiviral resistance in chronic hepatitis B.

[Pregnancy in active acromegaly]. / Schwangerschaft während aktiver Akromegalie.

HISTORY AND CLINICAL FINDINGS: A 29-year-old woman with a long-lasting history of oligoamenorrhea, fell pregnant shortly after being diagnosed with acromegaly. LABORATORY TESTS AND IMAGING: A high IGF-1 concentration and an oral glucose tolerance test confirmed the diagnosis. Cranial magnetic resonance imaging demonstrated a macroadenoma of the pituitary with suprasellar extension and compression of the optic chiasm leading to incomplete hemianopsia. TREATMENT AND COURSE: Transsphenoidal surgery was performed during the second trimester, impaired visual fields became normal and subsequent biochemical tests suggested remission. She delivered a healthy full-term infant via cesarean section after an uncomplicated pregnancy. The infant's development was unremarkable. Postpartum assessment showed persistent acromegaly activity and the patient was judged to require secondary multimodal therapy. CONCLUSIONS: Pituitary adenomas often cause oligoamenorrhea and may interfere with fertility. Although pregnancy rarely occurs during the course of active acromegaly, the maternal morbidity, including hypertension and gestational diabetes, is increased. While pregnancy may cause an increase in tumor size, biochemical improvement in acromegaly is--as illustrated by the present case--also possible. A maternal-to-fetal transfer of growth hormone or IGF-1 has not been proved.

Case report: human herpesvirus 6 reactivation associated with colitis in a lung transplant recipient.

Whereas human herpesvirus 6 (HHV-6) reactivation is frequent in solid organ transplant recipients, symptomatic disease is rare. A case of colitis associated with HHV-6B reactivation was observed in a lung transplant recipient. This case report suggests that symptomatic HHV-6 infection may occur in the absence of detectable viremia.

[Endogenous hypercortisolism and immunologically-mediated disease: three cases]. / Endogener Hypercortisolismus und immunologisch vermittelte Erkrankungen: drei Fälle.

HISTORY AND CLINICAL FINDINGS: We report three women with hypercortisolism presenting with symptoms and signs of Cushing's syndrome. In two of the patients, initial symptoms of hypercortisolism were associated with spontaneous amelioration of previously known atopic dermatitis and psoriasis, respectively. DIAGNOSTIC PROCEDURES: Diagnosis was established by demonstrating both lack of responsiveness to dexamethasone (1mg) suppression test and increased 24-hour urine cortisol secretion. One patient had a low serum ACTH level indicating Cushing's syndrome of adrenal origin. In the other two patients hypercortisolism proved to be ACTH-dependent, the source being the pituitary, as demonstrated by CRH stimulation test (elevation of ACTH and cortisol by 35 % and 20 %, respectively) and sampling of the petrosus sinus. In both patients imaging confirmed the presence of a pituitary adenoma. TREATMENT AND COURSE: All three patients underwent successful surgery: the first patient had an adrenalectomy, the other two transseptal transsphenoidal hypophysectomy. As symptoms and signs of hypercortisolism improved, the previously quiescent signs of atopic dermatitis and psoriasis recurred and one patient developed Graves' disease. CONCLUSIONS: Following successful treatment of endogenous hypercortisolism, symptoms of unrelated immunologically mediated conditions, especially autoimmune thyroiditis, may occasionally appear. Furthermore, the clinical course of coexisting immunologically mediated diseases may help to diagnose Cushing's syndrome and to monitor the patients after surgical treatment.

Involvement of connexin 43 in meiotic maturation of bovine oocytes.

In ovarian follicles, cumulus cells provide the oocyte with small molecules that permit growth and control maturation. These nutrients reach the germinal cell through gap junction channels, which are present between the cumulus cells and the oocyte, and between the cumulus cells. In this study the involvement of intercellular communication mediated by gap junction channels on oocyte maturation of in vitro cultured bovine cumulus-oocyte complexes (COCs) was investigated. The stages of oocyte maturation were determined by Hoechst 33342 staining, which showed that 90% of COCs placed in the maturation medium for 24 h progress to the metaphase II stage. Bovine COC gap junction communication was disrupted initially using n-alkanols, which inhibit any passage through gap junctions. In the presence of 1-heptanol (3 mmol l(-1)) or octanol (3.0 mmol l(-1) and 0.3 mmol l(-1)), only 29% of the COCs reached metaphase II. Removal of the uncoupling agent was associated with restoration of oocyte maturation, indicating that treatment with n-alkanols was neither cytotoxic nor irreversible. Concentrations of connexin 43 (Cx43), the major gap junction protein expressed in the COCs, were decreased specifically using a recombinant adenovirus expressing the antisense Cx43 cDNA (Ad-asCx43). The efficacy of adenoviral infection was > 95% in cumulus cells evaluated after infection with recombinant adenoviruses expressing the green fluorescence protein. RT-PCR performed on total RNA isolated from Ad-asCx43-infected COCs showed that the rat Cx43 cDNA was transcribed. Western blot analysis revealed a three-fold decrease in Cx43 expression in COCs expressing the antisense RNA for Cx43. Injection of cumulus cells with Lucifer yellow demonstrated further that the resulting lower amount of Cx43 in infected COCs is associated with a two-fold decrease in the extent of coupling between cumulus cells. In addition, oocyte maturation was decreased by 50% in the infected COC cultures. These results indicate that Cx43-mediated communication between cumulus cells plays a crucial role in maturation of bovine oocytes.

Adenovirus-mediated gene transfer into selected liver segments using a vascular exclusion technique.

Adenovirus-mediated gene therapy is hampered by severe virus-related toxicity, especially to the liver. The aim of the present study was to test the ability of a vascular exclusion technique to achieve transgene expression within selected liver segments, thus minimizing both viral and transgene product toxicity to the liver. An E1-E3-deleted replication-deficient adenovirus expressing a green fluorescent protein (GFP) reporter gene was injected into the portal vein of BDIX rats, with simultaneous clamping of the portal vein tributaries to liver segments II, III, IV, V, and VIII. GFP expression and inflammatory infiltrate were measured in the different segments of the liver and compared with those of the livers of animals receiving the viral vector in the portal vein without clamping. The GFP expression was significantly higher in the selectively perfused segments of the liver as compared with the non-perfused segments (p < 0.0001) and with the livers of animals that received the vector in the portal vein without clamping (p < 0.0001). Accordingly, the inflammatory infiltrate was more intense in the selectively perfused liver segments as compared with all other groups (p < 0.0001). Fluorescence was absent in lungs and kidneys and minimal in spleen. The clinical usefulness of adenovirus-mediated gene transfer to the liver largely depends on the reduction of its liver toxicity. Clamping of selected portal vein branches during injection allows for delivery of genes of interest to targeted liver segments. Transgene expression confined to selected liver segments may be useful in the treatment of focal liver diseases, including metastases.

A mutagenic PCR identifies isolates of Borrelia garinii responsible for Lyme borreliosis.

Borrelia garinii is one of the three major Borreliae responsible for Lyme borreliosis in Europe. We have characterized a protein of B. garinii (VS102) and a genomic fragment from the gene encoding this protein was cloned. The DNA sequence of the fragment showed high homology with a known gene of B. burgdorferi sensu stricto. The protein encoded by this gene in B. burgdorferi sensu stricto is a phosphocarrier protein (histidine-containing protein). A mutation T to G polymorphism at codon 57 was found to be specific to B. garinii. A PCR-based approach that allows the rapid detection of this mutation made it possible to specifically discriminate B. garinii from other B. burgdorferi genospecies with high sensitivity and specificity.

A rapid phenotypic assay for detection of acyclovir-resistant varicella-zoster virus with mutations in the thymidine kinase open reading frame.

Susceptibility assays by cell culture methods are time-consuming and are particularly difficult to perform with varicella-zoster virus (VZV). To overcome this limitation, we have adapted a functional test of the viral thymidine kinase (TK) in TK-deficient (tdk mutant) bacteria to detect ACV-resistant VZV in clinical samples. After PCR amplification, the complete viral TK open reading frame (ORF) is purified from PCR primers, digested with two restriction enzymes, and ligated in an oriented fashion into a bacterial expression vector. The ligation products are then used to transform tdk mutant bacteria. After transformation, an aliquot of the bacteria is plated onto a plate with minimal medium containing (i) ampicillin to select for plasmids carrying the viral TK ORF and (ii) isopropyl beta-D-thiogalactopyranoside (IPTG) to induce its expression. An identical aliquot of bacteria is also plated onto a medium containing, in addition to the components described above, 5-fluorodeoxyuridine (FUdR). Compared to the number of transformants on FUdR-free medium, the number of colonies carrying TK derived from susceptible strains was reduced by 86%, on average, in the presence of FUdR. In contrast, the number of transformants carrying TK from resistant strains with a mutant TK were reduced by only 4%, on average, on FUdR-containing plates. We have assessed the validity of this assay with cell culture isolates and several clinical samples including two cerebrospinal fluid samples from which no virus could be isolated. This colony reduction assay allowed the correct identification of the TK phenotype of each VZV isolate tested and can be completed within 3 days of receipt of the sample.