Aspect ratio of nano/microstructures determines Staphylococcus aureus adhesion on PET and titanium surfaces.

AIMS: Joint infections cause premature implant failure. The avoidance of bacterial colonization of implant materials by modification of the material surface is therefore the focus of current research. In this in vitro study the complex interaction of periodic structures on PET and titanium surfaces on the adhesion of Staphylococcus aureus is analysed. METHODS AND RESULTS: Using direct laser interference patterning as well as roll-to-roll hot embossing methods, structured periodic textures of different spatial distance were produced on surfaces and S. aureus were cultured for 24 h on these. The amount of adhering bacteria was quantified using fluorescence microscopy and the local adhesion behaviour was investigated using scanning electron microscopy. For PET structures, minimal bacterial adhesion was identified for an aspect ratio of about 0·02. On titanium structures, S. aureus adhesion was significantly decreased for profile heights of < 200 nm. Our results show a significantly decreased bacterial adhesion for structures with an aspect ratio range of 0·02 to 0·05. CONCLUSIONS: We show that structuring on surfaces can decrease the amount of S. aureus on titanium and PET as common implant materials. SIGNIFICANCE AND IMPACT OF THE STUDY: The study highlights the immense potential of applying specific structures to implant materials to prevent implant colonization with pathogen bacteria.

Endothelial cell responses to castor oil-based polyurethane substrates functionalized by direct laser ablation.

Surface-induced thrombosis and lack of endothelialization are major drawbacks that hamper the widespread application of polyurethanes for the fabrication of implantable cardiovascular devices. Endothelialization of the blood-contacting surfaces of these devices may avoid thrombus formation and may be implemented by strategies that introduce micro and submicron patterns that favor adhesion and growth of endothelial cells. In this study, we used laser radiation to directly introduce topographical patterns in the low micrometer range on castor oil-based polyurethane, which is currently employed to fabricate cardiovascular devices. We have investigated cell adhesion, proliferation, morphology and alignment in response to these topographies. Reported results show that line-like and pillar-like patterns improved adhesion and proliferation rate of cultured endothelial cells. The line-like pattern with 1 µm groove periodicity was the most efficient to enhance cell adhesion and induced marked polarization and alignment. Our study suggests the viability of using laser radiation to functionalize PU-based implants by the introduction of specific microtopography to facilitate the development of a functional endothelium on target surfaces.

Cochlear, auditory brainstem responses in Type 1 diabetes: relationship with metabolic variables and diabetic complications.

AIMS: Few studies have analysed the presence of hearing abnormalities in diabetes. We assessed the presence of subclinical auditory alterations and their possible association with early vascular and neurological dysfunction in young adults with Type 1 diabetes of long duration. METHODS: Thirty-one patients with Type 1 diabetes (mean age 33 ± 2.3 years, disease duration 25.7 ± 4.2 years) and 10 healthy controls underwent pure tone audiometry (PTA), distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) analyses. Associations with metabolic variables and chronic complications were explored. RESULTS: Compared with healthy controls, patients with diabetes had significantly higher mean hearing thresholds, although still within the normoacusic range. DPOAE intensities at medium frequencies (2.8-4 kHz) were significantly lower in patients with diabetes. In ABR, in addition to waves I, III and V, we observed the appearance of a visible wave IV in patients with diabetes compared with controls (prevalence 61% vs. 10%, P < 0.05), and its appearance was related to a prolonged I-V interval (4.40 ± 0.62 ms vs. 4.19 ± 0.58 ms, P < 0.05). Diastolic blood pressure was higher in people with abnormal DPOAE (P < 0.05), whereas systolic blood pressure correlated with wave V and interpeak I-V interval latencies. A trend towards an association between evidence of wave IV and the presence of somatic neuropathy or abnormal cardiovascular autonomic tests was observed. CONCLUSIONS: Young adults with long-term Type 1 diabetes have subclinical abnormalities in qualitative auditory perception, despite normal hearing thresholds, which might reflect neuropathic and/or vascular alterations.

Quantitative allocation of Bragg scattering effects in highly efficient OLEDs fabricated on periodically corrugated substrates.

Bragg scattering effects in bottom-emitting organic light-emitting diodes (OLEDs) grown on corrugated aluminum-doped zinc oxide electrodes are analyzed. Periodic corrugation is introduced by structuring the oxide electrode via UV laser ablation, a process that enables flexible adjustment of the period and height of corrugation. We demonstrate that fabrication of stable and electrically efficient OLEDs on these rough substrates is feasible. Sharp spectral features are superimposed onto the broad emission spectra of the OLEDs, providing clear evidence for Bragg scattering of light from guided modes into the air cone. Theoretical analysis based on an emissive dipole model and conservation of momentum considerations allows a quantitative description of scattering and the associated dispersion relations.

Contactless laser-assisted patterning of surfaces for bio-adhesive microarrays.

Micropatterned surfaces with cell adhesive areas, delimited by protein repellent microstructures, are in high demand for its potential use as relevant biological assays. This is not only because such surfaces allow directing cell growth in a spatially localized and restricted manner, but also because they can be used to elucidate basic cell growth and orientation mechanisms. Here, it is presented a laser-assisted micropatterning technique to fabricate large area microstructures of poly (ethylene glycol) hydrogel onto a cell adhesive surface: a biofunctional maleic anhydride copolymer. By varying photoinitiator, laser intensity, copolymer as well as the hydrogel layer thickness, the optimum conditions to produce high quality features were found. The suitability of these micropatterned substrates for bioassay applications was proved by cell adhesion studies. The introduced procedure could be used to prepare a broad range of microarrays for certain bioanalytical approaches and to create different types of biofunctional surfaces.

Spectrum and distribution of MECP2 mutations in 64 Italian Rett syndrome girls: tentative genotype/phenotype correlation.

We report a direct DNA sequencing analysis of the MECP2 gene undertaken on a further 64 Italian patients with Rett syndrome by using a LICOR 4200 Automated Sequencer. All of the girls entering the study had a consistent clinical diagnosis for this disorder. All coding regions and the flanking intronic splice site sequences were amplified as three non-overlapping fragments by using both forward and reverse primers. The results were then compared to the MECP2 reference sequences published in GenBank. Mutations of the MECP2 gene were identified in 64 of 75 (85.33%) unrelated sporadic Rett syndrome girls. Genotype/phenotype correlation studies, in particular in groups of patients with the same mutation, did not offer definitive and interesting data.

Dermatophytes and dermatophytoses in the Milan area between 1970 and 1989.

Between 1970 and 1989 we examined 13,019 patients with dermatophytoses in the Milan area, Northern Italy. The results obtained during the 1980-89 period were compared with those obtained in the years 1970-79. From the data collected, tinea corporis emerged as the most frequently observed dermatophytosis, followed by tinea pedis and unguium. As far as dermatophytes are concerned, the dermatological pattern is dominated by Microsporum canis and Trichophyton rubrum. Other species, such as Epidermophyton floccosum, T. mentagrophytes, M. gypseum, T. violaceum, T. verrucosum, T. tonsurans and T. schoenleinii, have progressively become less evident. Other mycetes, such as T. megninii, T. soudanense, M. langeroni, T. vanbreuseghemii, M. ferrugineum, sporadically isolated in the 1970-79 period, have disappeared in recent years. An analysis of the distribution and frequency of the dermatophytes according to the cutaneous area affected is reported.

Onychomycoses due to Microascus cirrosus (syn. M. desmosporus).

Microascus cirrosus is very rarely the aetiological agent of onychomycosis. We report two additional cases of toenail infections caused by this fungus.

Pityriasis versicolor of the face.

Pityriasis versicolor (p.v.) is a superficial mycosis occurring frequently on the face. Epidemiological and clinical data regarding cases of p.v. on the face over a period of 11 years are discussed and some explanation given for conditions which favour facial involvement. This study underlines that face lesions of p.v. are more common in children than in adults and in females than in males. The forehead is the site of facial involvement usually affected. Clinical features are variable but we often observed achromic or hypopigmented scaling lesions, smaller than trunk patches.

Tinea pedis in children.

Tinea pedis is a superficial mycosis, unusual in children. Epidemiological and clinical data regarding cases of tinea pedis observed in children over a period of 20 years are discussed and some explanation given for the conditions which predisposed children to the infection. Clinical features are variable and similar to adults. Bullous lesions are more frequently seen in children. Most of the cases were seen in children over 10 years of age. Males are more often affected with tinea pedis: this is particularly true for 10 to 13 year-old children. As in adults, Trichophyton rubrum is the most frequently isolated etiological agent.

Pityriasis versicolor in the pediatric age.

Pityriasis versicolor (PV) is a superficial mycosis, theoretically unusual in children. Epidemiologic and clinical data for children with PV over 11 years was collected. Some explanations are given for the conditions that favored this mycotic infection in children. This study confirms that the face is a usual site of PV in children, in contrast to its rarity as a site in adults. Clinical features are variable and similar to adults. Both sexes are equally affected. The family history is often positive for PV.

Tinea capitis in adults.

Scalp ringworm is unusual after puberty. Etiological, epidemiological and clinical data regarding cases of tinea capitis in the elderly observed over a period of 15 years are discussed and some explanations are given for the conditions which favoured the mycotic infection of the scalp in adults. This study underlines that tinea capitis in the elderly is usually characterized by very variable and often atypical lesions and that female preponderance in adult cases of scalp ringworm is striking and unexplained. Moreover, all the dermatophytes we isolated from scalp lesions in children can cause tinea capitis in adults.

Drug-induced changes in the plasma membrane of Microsporum canis. A preliminary freeze--fracture study.

Commercial solutions of clotrimazole, tolnaftate and tolcyclate were tested for 12 h in cultures of Microsporum canis. They induced modifications in particle distribution, a blebbing of particle-free areas and the appearance of lamellar figures on the plasma membrane of fungus cells. The first two changes in the plasma membrane might be ascribed to a modification of the spectrin-like meshwork, while the third could be the result of a crystalline organization of membrane lipids.