The effect of surface chemistry and nanotopography of titanium nitride (TiN) films on primary hippocampal neurones.

The cell-substrate interaction of primary hippocampal neurones with thin films of TiN was studied in vitro. TiN films of different surface chemistries and topographies were deposited by pulsed DC reactive magnetron sputtering and closed field unbalanced magnetron sputter ion plating by Teer Coatings Ltd., Hartlebury, UK to result in TiN films with similar surface chemistries but different topographical features. TiN films were characterised using X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. The neuron-substrate interaction was examined using environmental scanning electron microscopy (FEG-ESEM) for morphological information. Bromodeoxyuridine and TUNEL assays were used to identify proliferating neurones as well as apoptotic neurones. Fluorescent staining for MAP-2 was used to label neuronal network formation. Primary hippocampal neurones were found to attach and spread to all of the TiN film chemistries and topographies investigated. Neuronal network morphology appeared to be more preferential on the nitrogen rich TiN films and also with reduced nanotopographical features.

The effect of surface chemistry and nanotopography of titanium nitride (TiN) films on 3T3-L1 fibroblasts.

The cell-material interaction of 3T3-L1 fibroblasts with TiN films was studied in vitro. TiN films were deposited onto glass substrates to thicknesses of 0.2 and 1.0 microm by pulsed dc reactive magnetron sputtering. For comparison TiN films were deposited by closed field unbalanced magnetron sputter ion plating by Teer Coatings Ltd. (Hartlebury, UK) to result in TiN films with similar surface chemistries but having increased topographical features. TiN films were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy. The cell-material interaction was examined morphologically by monitoring fibroblast attachment and growth and comparing to a control substrate. At early time points increased numbers of 3T3-L1 fibroblasts were found to preferentially attach to TiN films with an increase in the percentage of surface interstitial nitrogen and also with decreased topographical features. At later time points the presence of nanotopography appeared to play a greater role than the effects of surface chemistry and resulted in increased numbers of attached 3T3-L1 fibroblasts. The results show that by changing the deposition route and parameters to produce TiN films, the resultant films can be used to investigate the cellular response to surfaces of differing chemistry and topography.

The effect of surface chemistry and structure of titanium nitride (TiN) films on primary hippocampal cells.

Thin films of TiN were investigated as a candidate microelectrode material for multi-electrode arrays, which are used for recording from electrically active cells in culture. TiN films were deposited onto glass substrates by DC pulsed reactive magnetron sputtering. The structure, phase composition and surface chemistry were studied using X-ray diffraction (XRD), Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The biocompatibility of the TiN films was examined morphologically by monitoring neuronal network formation and comparing this to a control substrate. Results indicate that neuronal cell adhesion and growth is influenced by the surface chemistry and associated crystal orientation of the TiN thin films.

Bedsharing, temperament, and sleep disturbance in early childhood.

STUDY OBJECTIVE: Temperament was explored as a factor in both night-waking and bedsharing in preschool-aged children. DESIGN: Bedsharers and solitary sleepers were categorized based on the frequency of current bedsharing. MANOVA was used to examine associations among temperament and sleep measures. SETTING: Two preschools affiliated with a rural university in the Northeast United States. Participants. 67 children between 2.4-5.6 years of age from two University-affiliated preschools were studied. INTERVENTION: Child temperament was rated by parents and teachers using the Carey Temperament Scale and compared to night-waking, current sleep habits, and the circumstances in which bedsharing occurred MEASUREMENTS AND RESULTS: Parents and preschool teachers completed the Carey Temperament Scale for 3-7 year olds. Parents also scored the Sleep Habits Inventory and the Sleeping Arrangements Inventory, which provided a current and retrospective history of the child's sleep location and sleep patterns. Parents' ratings showed that bedsharers have less regular bedtimes; difficulty with sleep onset; more night-waking; and seek out the parents following awakening during the night. Temperamentally, bedsharers were found to be more intense and exhibit less adaptability and rhythmicity. However, teachers' temperament ratings did not predict bedsharing and were not concordant with parental ratings. CONCLUSIONS: These findings suggest that bedsharing at preschool age is a complex phenomenon related to parents' ratings of child temperament, sleep habits, and disturbances such as night waking. Implications for the clinical assessment of sleep disorders are discussed.

Lactic acid-stabilised albumin for microsphere formulation and biomedical coatings.

Microspheres of ovalbumin (OVA) ranging from 1 to 15 microm were prepared by emulsifying an aqueous solution of albumin in soya oil at room temperature then raising the temperature to 45 degrees C for 30 min, prior to harvesting of the microspheres. Production of OVA nanospheres with size less than 500 nm was achieved by desolvation from aqueous albumin solutions using acetone. In both cases, lactic acid was added to the starting albumin solution to stabilise the resulting particles. Utilisation of an endogenous substance avoids the use of chemical crosslinking agents such as glutaraldehyde and associated toxicological concerns. Protein coating of knitted Dacron vascular grafts was performed by impregnation of the textile structure with lactic acid-stabilised ovalbumin nanospheres thereby providing a surface potentially resistant to blood platelet adhesion but conducive to endothelialisation. Protein release testing carried out in PBS at 37 degrees C revealed that approximately 60% of the original albumin coating was retained by the Dacron graft material after 4 days and remained at this level for upto 4 weeks. Apart from the formulation of albumin microspheres for drug delivery, diagnostic applications and coating of biomedical textiles, the process of albumin stabilisation using lactic acid may be usefully applied to improve protein immobilisation on a wide range of biomaterial surfaces.

Protein adsorption and platelet attachment and activation, on TiN, TiC, and DLC coatings on titanium for cardiovascular applications.

The hemocompatibility of a TiN/TiC/diamond-like carbon (DLC) multilayer structure, deposited on titanium substrates for use as coatings for a heart valve prosthesis, has been studied through the adsorption of blood proteins and the adhesion and attachment of blood platelets. All of the surfaces were characterized by stylus profilometry and water contact angles. The adsorption of albumin and fibrinogen to the surfaces was assessed using the Amido Black assay, whereas platelet attachment was studied by scanning electron microscopy and quantified using stereological techniques. The degree of platelet spreading on the surfaces was seen to correlate with differences in surface energy, indicated from contact angle measurements. The greatest spreading was seen on the more hydrophilic surfaces. When studying protein adsorption to the surfaces, no correlation could be determined between contact angle results and levels of adsorption, although the most hydrophilic surfaces did appear to promote greater amounts of fibrinogen adsorption. Thrombus formation was observed to some degree on all of the surfaces, with the exception of the DLC coating. This coating also promoted less spreading of platelets than the other surfaces. The good hemocompatibility of the DLC coating is attributed to its hydrophobicity and smooth surface, resulting in a higher ratio of albumin to fibrinogen than any of the other surfaces.

Biocompatibility of Laser-deposited Hydroxyapatite Coatings on Titanium and Polymer Implant Materials.

We have investigated the biocompatibility of calcium phosphate coatings deposited by pulsed laser ablation from hydroxyapatite (HA) targets onto polyethylene and Teflon substrates. It was found that the cell density, attachment, and morphology of primary rat calvaria osteoblasts were influenced by both the original polymer and by the nature of the apatite coatings. HA coatings on Teflon were found to have higher biocompatibility in terms of cell adhesion and spreading. In vivo studies of bone response to coatings deposited by KrF excimer and CO2 lasers on commercial Ti6A14V alloy implants show that both deposition techniques suppress fibrous tissue formation and promote osteogenesis. © 1998 Society of Photo-Optical Instrumentation Engineers.

Effects of ACTH and aminoglutethimide on the catecholamine content and chromaffin cell morphology of the adrenal medulla of the neonatal rat.

The rat adrenal medulla is immature at birth, composed of phaeochromoblasts and undifferentiated chromaffin cells, but by 7 d postnatally morphologically distinct adrenaline-storing (A) and noradrenaline-storing (NA) cells can be distinguished in the adult proportions of approximately 80-85% A and 15-20% NA cells. Glucocorticoid hormones are known to play an important role in the initial expression and maintenance of phenylethanolamine N-methyl transferase (PNMT), the enzyme characteristic of A cells. The purpose of the study was to investigate the effects of glucocorticoids on the establishment of the A and NA cell phenotype in vivo during the first postnatal week. Neonatal rats were treated from postnatal d 1 to 7 either with ACTH to increase circulating levels of glucocorticoids or with aminoglutethimide to reduce blood glucocorticoids. On postnatal d 7 the volume fractions of A and NA cells in the adrenal medulla were estimated and the amounts of stored adrenaline and noradrenaline determined by HPLC and compared with untreated controls. Adrenaline levels were increased following ACTH treatment and there was an apparent decrease after aminoglutethimide which was not statistically significant. There was cytological evidence of the effects of ACTH and aminoglutethimide on the adrenal cortex but no resultant effect on medullary cell morphology. A cells remained predominant with NA cells making up approximately 15% of chromaffin cells, suggesting that any effects of altered glucocorticoid levels were confined to a modulation of adrenaline synthesis by a morphologically unchanged chromaffin cell population.(ABSTRACT TRUNCATED AT 250 WORDS)