Roughness response genes in osteoblasts.

Titanium (Ti) and Ti alloys are widely used as dental and orthopedic implants, but the effects of the surface characteristics of these materials, including roughness, on the response of target tissues in vivo are not well understood. The present study has therefore examined the effects of a moderately rough (sand-blasted, acid-etched; SLA) Ti surface, a highly rough (plasma-sprayed; TPS) surface, and a smooth surface (SMO) on bone cells in vitro. X-ray photoelectron spectroscopy showed that these surfaces had similar surface chemistry, while scanning electron microscopy suggested that the SLA provided a transiently less biocompatible surface, with initially less well-attached cells. SLA also delayed bone cell growth compared with SMO, whereas the TPS surface elicited the greatest increase in cell numbers. In addition, expression profiling using the ATLAS gene array showed marked differences in gene responses after 3 h of incubation; this increased further after 24 h, with TPS generating the largest number of up- and down-regulated genes compared with SLA and SMO. A number of osteoblast genes were also identified as 'roughness' genes on the basis of their similar response on SLA and TPS, compared with SMO. These findings show, for the first time, that the surface roughness of Ti has a profound effect on the profile of genes expressed by bone cells and suggest that improvements in the biological activity and possibly the clinical efficacy of these materials could be achieved by selective regulation of gene expression mediated via modification of surface roughness.

Chlorhexidine release from an experimental glass ionomer cement.

Glass ionomer cements (GIC) can potentially be used as matrices for the slow release of active species, as has been shown previously for fluoride ions. This study investigated the use of an experimental GIC as a carrier for the release of chlorhexidine acetate (CHA) at included concentrations ranging from 0.5% to 13.0% of CHA by weight. Release into water was examined using high-performance liquid chromatography. All measurable chlorhexidine was released within 22 h1/2, however this was less than 10% of the total mass incorporated in the specimens. An increased percentage of CHA incorporated into the powder gave an increased release into the surrounding water. The bulk of the CHA was retained within the cement. For comparison, the surface chemistry of a CHA-containing GIC was examined using X-ray photoelectron spectroscopy before and after prolonged immersion in water. This confirmed retention of a large amount of CHA. Spectra after leaching appeared very similar to those from a CHA-free GIC after immersion in a CHA solution. In order to explore the effect of CHA-inclusion on the cement properties, compressive strengths, working and setting times were also measured. In general, compressive strengths were found to be decreased in direct proportion to the quantity of CHA added, while working and setting times increased.

Human alveolar bone cell adhesion and growth on ion-implanted titanium.

Surface characteristics play a vital role in determining the biocompatibility of materials used as bone implants. Calcium ion implantation of titanium was previously reported to enhance osseointegration and bone formation in vivo, although the lack of consistent and reproducible effects highlight the need to understand the basic mechanisms involved in the response of target cells to such surfaces. The aim of this study was therefore to measure the precise effects of ion implantation of titanium on bone cells in vitro. Alveolar bone cells were seeded on the surface of polished titanium disks implanted with calcium, potassium, and argon ions. Using radioisotopically tagged bone cells, the results showed that although the calcium ion implanted surface reduced cell adhesion, it nevertheless significantly enhanced cell spreading and subsequent cell growth. In contrast, few differences in bone cell behavior were observed between the potassium- and argon-implanted titanium and the control nonimplanted titanium disks. These findings suggest the possibility that the calcium-implanted surface may significantly affect the biocompatibility of titanium implants by enhancing bone cell growth. Surface modification by ion implantation could thus prove to be a valuable tool for improving the clinical efficacy of titanium for bone repair and regeneration in vivo.

Fluoride uptake by glass ionomer cements: a surface analysis approach.

Despite extensive research, the mechanism by which glass ionomer cements take up fluoride ions from solution remains unclear. To date, the majority of studies have concentrated on measuring the removal of ions from solution. In this study, we demonstrate the application of X-ray photoemission spectroscopy and secondary ion mass spectrometry to the surface analysis of the cements, after the introduction of fluoride either by doping or by immersion. Fluoride ion uptake from potassium fluoride solution is correlated with the formation of a surface layer which is rich in calcium as well as fluoride.

Adhesion of bone cells to ion-implanted titanium.

The use of ion-implantation to encourage osseointegration has been investigated using an in vitro model cell culture system and surface analysis. Polished titanium discs were implanted with calcium, potassium and argon ions. The adhesion of bone-derived cells was measured using radioactively labeled cells and the morphology examined using scanning electron microscopy. Similar numbers of cells were found to adhere to the potassium and argon-implanted titanium as to control (non-implanted) titanium. However, adhesion to the calcium-implanted titanium discs was significantly reduced. Moreover, although the cells were found to be well spread on the calcium and potassium-implanted titanium, a much greater proportion of cells appeared to remain rounded and poorly attached on the argon-implanted surface. These differences are discussed in relation to the observed surface roughness and chemistry, which were assessed using interferometry and X-ray photoelectron spectroscopy, respectively.

Reporting IDS home office costs for Medicare reimbursement.

Under Medicare, providers that are part of a chain can be reimbursed for an allocable portion of allowable home office costs. Before a provider can be reimbursed for these costs, however, a home office cost statement must be submitted to the providers' fiscal intermediary. The statement provides a means of allocating certain home office costs to the provider components of a system so that providers can be reimbursed directly for these costs. The home office cost statement also offers a useful financial overview of the home office's operations in relation to the system's overall operations.

Cerebrospinal fluid immunoelectrophoresis in multiple sclerosis.

In 95 patients with definite multiple sclerosis (MS) cerebrospinal fluid (CSF) cytomorphology, protein electrophoresis and immunoelectrophoresis using antisera to human serum, Fab fragments of immunoglobulin G(IgG) and to kappa and lambda light chains and the CSF IgG concentration were examined. In the CSF diagnosis of MS, the set of the examinations used is considered to be superior to any individual laboratory technique currently applied in the diagnostic process of MS. In the set of the CSF examinations, CSF immunoelectrophoresis revealed abnormal findings in patients with MS in whom presence of bands (oligoclonal gammopathy) in the gamma-globulin field of the CSF electropherogram and/or increased concentration of CSF IgG were not demonstrated.

Planning for the next generation of risk studies.

Seventy longitudinal studies of social competence in children conducted over the past 3 decades are critically reviewed in an effort to pinpoint current and potential problems in conducting longitudinal research with samples of children at elevated risk for developing severe forms of psychopathology. The review outlines chronic problems in accurately specifying objectives, choosing adequate and appropriate samples, and selecting maximally useful predictor and outcome measures in this reseach area. A variety of institutional and organizational problems that make risk research difficult to undertake and to carry to completion are also described. A federation of risk projects, which could seek unified funding and coordinate institutional support, is suggested. In addition, new grant review procedures that embody coordination of management efforts between funding and research agencies are recommended as one possible alternative to present practices.

Pyramid training of elementary school teachers to use a classroom management "skill package".

Three regular elementary teachers were trained in the use of a classroom management "skill package". Subsequently, each of these three teachers (tier 1 of training) trained three more teachers to use the same skill package (tier 2 of training). Direct behavioral measures of student disruptiveness were taken in the three tier-1 classrooms and four tier-2 classrooms, and permanent product measures of student productivity in arithmetic were taken in the three tier-1 classrooms. Results indicated that student disruptiveness decreased at least as much in the tier-2 classrooms as in the tier-1 classrooms. Data also indicated that serving as trainers benefited two of the tier-1 teachers who profited least from the original training by producing further reductions in disruptiveness in their respective classrooms. Productivity data suggested that use of the "skill package" increased classroom academic output, especially for those students below the median in productivity during baseline. The investigators' time investment in training a tier-2 teacher was one-fourth that of training a tier-1 teacher.

Role playing to train elementary teachers to use a classroom management "skill package".

Two teachers who led regular third-grade classrooms in a suburban elementary school were trained via role-playing to use a broad range of social skills in dealing with group behavioral management in the classroom. Teacher training reduced disruptive student behavior during both seat work and group discussions in both classrooms. A measure of student productivity during arithmetic period in one classroom showed significant gains in arithmetic problems correct per day for the middle and bottom thirds of the class, with the bottom third increasing by 76%.