Low temperature nucleation of thermochromic VO2crystal domains in nanocolumnar porous thin films.

The low temperature formation of monoclinic VO2crystal domains in nanocolumnar vanadium/oxygen thin films prepared by magnetron sputtering at oblique angles is analyzed. The synthesis procedure involved the deposition of amorphous nanocolumnar VO1.9thin films at room temperature and its subsequent annealing at temperatures between 250 °C and 330 °C in an oxygen atmosphere. The thermochromic transition of these films was found at a temperature of 47 °C when the annealing temperature was 270 °C and 58 °C when the annealing temperature was 280 °C and 290 °C, presenting a clear drop of the optical transmittance in the infrared region of the spectrum. The significant downshift in the temperature window to obtain VO2in comparison with compact films and other strategies in literature is explained by the particular morphology of the nanocolumnar structures, which contains numerous defects along with open and embedded porosity.

Growth dynamics of nanocolumnar thin films deposited by magnetron sputtering at oblique angles.

The morphology of numerous nanocolumnar thin films deposited by the magnetron sputtering technique at oblique geometries and at relatively low temperatures has been analyzed for materials as different as Au, Pt, Ti, Cr, TiO2, Al, HfN, Mo, V, WO3and W. Despite similar deposition conditions, two characteristic nanostructures have been identified depending on the material: a first one defined by highly tilted and symmetric nanocolumnar structures with a relatively high film density, and a second one characterized by rather vertical and asymmetric nanocolumns, with a much lower film density. With the help of a model, the two characteristic nanostructures have been linked to different growth dynamics and, specifically, to different surface relaxation mechanisms upon the incorporation of gaseous species with kinetic energies above the surface binding energy. Moreover, in the case of Ti, a smooth structural transition between the two types of growths has been found when varying the value of the power used to maintain the plasma discharge. Based on these results, the existence of different surface relaxation mechanisms is proposed, which quantitatively explains numerous experimental results under the same conceptual framework.

Human papillomavirus combined with cytology and margin status identifies patients at risk for recurrence after conization for high-grade cervical intraepithelial neoplasia.

OBJECTIVE: To compare the ability of cytology, human papillomavirus (HPV) testing and co-testing to identify recurrence of patients treated by loop electrosurgical excision procedure (LEEP) for cervical intraepithelial neoplasia (CIN) 2-3. MATERIALS AND METHODS: Retrospective analysis (R.A.): the medical records of 372 women treated for CIN 2-3 were reviewed. Resection margin, HPV typing, Pap smears, and biopsies post-LEEP were collected. Prospective analysis (P.A.): 97 women were followed post-LEEP by cytology, HPV test and colposcopy every six months. RESULTS: Positive margins were found to be an independent risk factor for recurrent disease (OR 0.192; 95% CI 0.074-0.497 in R.A. and OR 0.096; 95% CI 0.023-0.392 in P.A.). HPV testing showed less sensitivity than cytology (69% vs 84%, respectively in R.A. and 80% vs 100% in P.A.). Co-testing predicted recurrent disease at a sensitivity of 90.6% in R.A. and 100% in P.A. CONCLUSION: Co-testing is the best option in follow-up protocols after treatment for CIN 2-3. If margins are free and co-testing is negative at six and 12 months, 18 months visit could be avoided.

A new bottom-up methodology to produce silicon layers with a closed porosity nanostructure and reduced refractive index.

A new approach is presented to produce amorphous porous silicon coatings (a-pSi) with closed porosity by magnetron sputtering of a silicon target. It is shown how the use of He as the process gas at moderated power (50-150 W RF) promotes the formation of closed nanometric pores during the growth of the silicon films. The use of oblique-angle deposition demonstrates the possibility of aligning and orientating the pores in one direction. The control of the deposition power allows the control of the pore size distribution. The films have been characterized by a variety of techniques, including scanning and transmission electron microscopy, electron energy loss spectroscopy, Rutherford back scattering and x-ray photoelectron spectroscopy, showing the incorporation of He into the films (most probably inside the closed pores) and limited surface oxidation of the silicon coating. The ellipsometry measurements show a significant decrease in the refractive index of porous coatings (n(500 nm) = 3.75) in comparison to dense coatings (n(500 nm) = 4.75). The capability of the method to prepare coatings with a tailored refractive index is therefore demonstrated. The versatility of the methodology is shown in this paper by preparing intrinsic or doped silicon and also depositing (under DC or RF discharge) a-pSi films on a variety of substrates, including flexible materials, with good chemical and mechanical stability. The fabrication of multilayers of silicon films of controlled refractive index in a simple (one-target chamber) deposition methodology is also presented.

Enhancing Specific Disruption of Intracellular Protein Complexes by Hydrocarbon Stapled Peptides Using Lipid Based Delivery.

Linear peptides can mimic and disrupt protein-protein interactions involved in critical cell signaling pathways. Such peptides however are usually protease sensitive and unable to engage with intracellular targets due to lack of membrane permeability. Peptide stapling has been proposed to circumvent these limitations but recent data has suggested that this method does not universally solve the problem of cell entry and can lead to molecules with off target cell lytic properties. To address these issues a library of stapled peptides was synthesized and screened to identify compounds that bound Mdm2 and activated cellular p53. A lead peptide was identified that activated intracellular p53 with negligible nonspecific cytotoxicity, however it still bound serum avidly and only showed a marginal improvement in cellular potency. These hurdles were overcome by successfully identifying a pyridinium-based cationic lipid formulation, which significantly improved the activity of the stapled peptide in a p53 reporter cell line, principally through increased vesicular escape. These studies underscore that stapled peptides, which are cell permeable and target specific, can be identified with rigorous experimental design and that these properties can be improved through use with lipid based formulations. This work should facilitate the clinical translation of stapled peptides.

The 5,6- and 4,5-benzo derivatives of 1-hydroxy-7-azabenzotriazole.

[structure: see text]. Syntheses of the two benzo derivatives of HOAt are described. Conversion of the two isomers to the corresponding onium-style coupling reagents gave in one case a guandinium species 14 and in the other, presumably as a result of steric factors, a uronium species 15. The two systems are compared as to their effectiveness in peptide coupling processes.

Screening corneas for human immunodeficiency virus type 1 proviral DNA by polymerase chain reaction.

PURPOSE: We evaluated the sensitivity of the polymerase chain reaction as a technique to directly screen potential donor corneas for human immunodeficiency virus type 1 (HIV-1) proviral DNA. METHODS: DNA from the central 8.0-mm cornea, limbal cornea, aqueous humor, and retina from 22 eyes of 11 cadavers seropositive for HIV was extracted and amplified by polymerase chain reaction using primers specific for the gag and env regions of the HIV-1 genome. The identity of amplification products was confirmed by Southern blot hybridization. RESULTS: Viral DNA was detected in four (18.2%) of 22 central corneas, one (4.5%) of 22 limbal corneas, one (6.3%) of 16 aqueous humor samples, and seven (31.8%) of 22 retinas. No correlation was noted between the presence of HIV-1 proviral DNA in samples from the central cornea and from the other tissues tested from the same eye. CONCLUSIONS: Within the limits of our assay, processing and analysis of limbal cornea, aqueous humor, and retina by polymerase chain reaction may not reliably ascertain the presence of HIV-1 in the central, transplantable cornea.

Superficial hypertrophic dendriform epitheliopathy post-keratoplasty.

PURPOSE: To describe a distinct and unusual superficial dendriform keratopathy that can be seen in postkeratoplasty eyes. METHOD: Three Caucasian women in their sixth decade of life were referred to the Corneal and External Disease Service at the University of California, Davis, and underwent penetrating keratoplasty for different diagnoses. After keratoplasty, hypertrophic dendriform epithelial lesions were observed. These were refractory to debridement as well as topical antibiotic and steroid combinations. Immunofluorescent antibody testing was performed in all cases to rule out herpetic infection, and the patients were treated with nonpreserved lubricants and medications to eliminate medication toxicity as the cause of the lesions. RESULTS: All three patients in this series developed raised, hypertrophic epithelial lesions after keratoplasty, which were refractory to therapy. Comfort and mild increase in visual acuity were restored with the use of thin, moderate water content therapeutic contact lenses. CONCLUSIONS: Superficial hypertrophic dendriform epitheliopathy is a distinct syndrome that occurs postkeratoplasty in patients with preexisting chronic ocular inflammation, tear dysfunction, and/or lid disease exacerbated by the toxic effects of postoperative topical medication.

In vitro and in vivo effects of polyhexamethylene biguanide against herpes simplex virus infection.

PURPOSE: The differential diagnosis of Acanthamoeba keratitis frequently includes herpes simplex viral keratitis. Previous in vitro studies with chlorhexidine, a drug with antiacanthamoebic action, have suggested concomitant antiviral activity against herpes simplex virus. We tested another related antiacanthamoebic compound, polyhexamethylene biguanide (PHMB), to determine its activity against herpes simplex virus (HSV) in vitro and herpes simplex viral keratitis in vivo. METHODS: Equal aliquots of HSV-1 (McKrae) strain were incubated in a medium with no PHMB or with PHMB at 0.01, 0.02, or 0.05 for 5 min at 35 degrees C and the inoculum was then titered on a monolayer of E-2 cells (human corneal fibroblasts). Monolayers were examined on consecutive days and the percentage of plaque reduction was calculated. Eighteen rabbits (36 eyes) were inoculated with HSV-1 McKrae strain (10(5) pfu [plaque-forming units]/per eye). Rabbits were divided into three groups and treatment was initiated on day 3 postinfection. Group I received trifluorothymidine, group II received PHMB, and group III received artificial tears, each given five times daily in both eyes until day 10. Daily corneal swabbing to detect viral shedding and slit-lamp examination every 3 days were performed during this period. RESULTS: In vitro studies showed 62.5, 100, and 100% plaque reduction with 0.01, 0.02, and 0.05% PHMB, respectively. Slit-lamp examination of the rabbit corneas revealed faster resolution of dendrites in animals in group I treated with trifluorothymidine. Virus was not recoverable from corneal swabs in nine of 10 rabbits in group I by day 5, but all animals in groups II and III were still shedding HSV through day 8. CONCLUSION: Although PHMB has potent in vitro activity against HSV, it was not an effective treatment in the in vivo rabbit model of primary HSV keratitis at the concentration commonly used for treatment of Acanthamoeba infection. This suggests that 0.02% PHMB will not provide adequate antiherpetic coverage with treatment of keratitis of undetermined etiology in which the clinical differential diagnosis includes both herpes simplex and Acanthamoeba.

Antimicrobial efficacy and corneal endothelial toxicity of DexSol corneal storage medium supplemented with vancomycin.

Despite the presence of gentamicin in corneal storage medium, postoperative endophthalmitis may result from the transmission of bacteria via contaminated corneal tissue. The authors evaluated the antimicrobial activity and endothelial toxicity of vancomycin (10 micrograms/ml) in combination with gentamicin (100 micrograms/ml) in DexSol corneal storage medium. When tested against a panel of common ocular pathogens, vancomycin combined with gentamicin proved more effective than gentamicin alone for inhibiting the growth of Streptococcus pneumoniae at 4 degrees C after 1- and 5-day incubation periods. Ultrastructural and morphometric analyses of paired human corneas stored for 5 days in either DexSol supplemented with vancomycin combined with gentamicin or DexSol with gentamicin alone did not show a significant difference in endothelial toxicity between the two groups. These results suggest that vancomycin combined with gentamicin has superior antimicrobial effect and similar corneal toxicity when compared with media supplemented with gentamicin alone.