Biomedical subjects

B Overton

Publications and source records attributed to B Overton.

4 recordsLinked to original sources

PubMed1997

The effects of immunoglobulins on the convective permeability of human dentine in vitro.

Immunoglobulin molecules are localized in the dentinal tubules of non-carious and carious teeth, but their possible role in caries invasion is not understood. This study sought to examine the effects of immunoglobulin molecules on dentine permeability using a fluid-filtration method. Crown segments cut from impacted human third molars were treated by filtration with 100 micrograms/ml IgG, 100 micrograms/ml IgA or 30 micrograms/ml IgM under a constant pressure. Flow rates were recorded and percent changes in flow rate analysed over time. Filtrates collected at various times were tested for changes in immunoglobulin concentrations by an enzyme-linked immunosorbent assay, and the percent retention of immunoglobulins to dentine was calculated. There was a decreasing non-linear exponential relation between the percent changes in flow rate and filtration time for all three immunoglobulins. The percentage of retained immunoglobulins was significantly related to the filtration time for all three classes of immunoglobulins. Immunoglobulin retention contributed to significant changes in flow rate with time. These in vitro results indicate the potential mechanism of immunoglobulins in decreasing tabular permeability.

Dental Caries↗

PubMed1997

Transferrin is necessary and sufficient for the neural effect on growth in amphibian limb regeneration blastemas.

Cell proliferation during the early phase of growth in regenerating amphibian limbs requires a permissive influence of nerves. Based on analyses of proliferative activity in denervated blastemas, it was proposed that nerves provide factors important for cells to complete the proliferative cycle rather than for mitogenesis itself. One such factor, the iron-transport protein transferrin (Tf), is abundant in regenerating peripheral nerves where it is axonally transported and released at growth cones. Using blastemas in organ culture, which have been widely used in previous investigations of the neural effect on growth, it was shown here that the growth-promoting activity of neural extract was completely removed by immuno-absorption with antiserum against Tf and restored by addition of Tf. Purified Tf or a low molecular weight ferric ionophore were as active as the neural extract in this assay, indicating that the trophic effect of Tf involves its capacity for iron delivery. Both Tf and ferric ionophore also maintained DNA synthesis in denervated blastemas in vivo. A dose-response assay indicated that purified axolotl Tf stimulates growth of cultured blastemal cells at concentrations as low as 100 ng/mL. The Tf mRNA in axolotl nervous tissue was shown by northern analysis to be similar in size to that of liver. These results are discussed together with those from previous in vitro studies of blastemal growth and support the hypothesis that cell division in the blastema depends on axonally released Tf during the early, nerve-dependent phase of limb regeneration.

Ambystoma↗

PubMed1994

Improving mouth guards.

Mouth guards and materials were tested to provide information for a more protective yet more comfortable product. Ethylene-vinyl acetate copolymer materials varying in thickness and stiffness were tested for their mechanical, thermal, and water-absorption properties. Thickness was measured before and after fabrication of the mouth guard. During fabrication, thicknesses decreased from 25% to 50% for the custom-fabricated mouth guards and 70% to 99% for the mouth-formed (boil-and-bite), off-the-shelf, over-the-counter mouth guards. The thicker the material is, the greater the resulting energy absorption is. It is therefore essential that the thickness in the occlusal portion of the mouth guard remain optimal after fabrication. A mouth guard with a stiffer insert, which softens at a higher temperature in the occlusal portion, is proposed as a more protective mouth guard.

Absorption↗

PubMed1991

The black and deaf movements in America since 1960. Parallelism and an agenda for the future.

This paper traces the political and educational movements of both black and hearing-impaired Americans since 1960 and compares their common as well as disparate but equally significant experiences. The purpose of the comparisons is to identify problems and proven solutions that collectively suggest a strategy for the continuing movement of hearing-impaired people. The authors, through their ethnicity--three are black and two are white--and personal and professional experiences bring divergent but relevant points of view to the question of multicultural coalitions and their abilities to effect social change. Four principles or suggestions for advancing the agenda of hearing-impaired Americans are presented: (1) the need to define the issues that will continue to confront hearing-impaired Americans through the year 2000, (2) the need to enlarge the membership and participation of existing coalitions, (3) the need to address local, vocational, technical, and educational issues, and (4) the need to facilitate hearing-impaired networking groups within religious, social, business, and cultural organizations.

Black or African American↗