Cellular responses to metal ions released from implants.

In the process of calcified tissue formation, cells secrete a protein-rich matrix into which they add a metal ion that nucleates in the presence of phosphorus to form an inorganic salt (usually calcium hydroxyapatite). Cellular and tissue responses to metal ions-released from implants, for example-can therefore be considered from the perspective of how cells handle calcium ions. A critical factor in determining cellular toxicity will be free ion concentrations and the competitive interactions that occur in a physicochemical manner. Three of the parameters used to assess the biocompatibility of implant materials are (1) the ability to influence mitotic activity, (2) intercellular adhesion, and (3) promotion of cell death. A spectrum of responses to free intracellular calcium ions can be identified, ranging from presence of the ion being essential for cell division through to an excess of the free ion that results in cell death (apoptosis). In between these extremes, cells may become postmitotic and express phenotypic variations as they adapt to their environment and establish equilibrium to maintain intracellular calcium homeostasis. The response of cells to implants can be linked to ions released and interactions between these and other ions and/or molecules present in the tissues, similar to the manner in which cells handle calcium ions.

Contactless magneto-permeabilization for intracellular plasmid DNA delivery in-vivo.

Electroporation, an attractive process for delivering DNA and other molecules into target cells in vivo and in vitro is limited by the necessity of electrodes that need to be in contact with the subject or object to be electroporated. We have used magnetic fields, which do not require material contact with the subject, to temporarily permeabilize cells in guinea pig skin in vivo to enhance uptake and expression of GFP plasmid DNA. The results show for the first time that magnetic fields can trigger a process likely similar to electroporation. In designing the magnetic pulses, our most important criterion was a high rate of change of the magnetic field, based on the principle described by Michael Faraday which is expressed by the formula: E = -dB/dt, (E, electric field, B, magnetic field, t, time). Magnetic fields were generated by a flat electromagnet in a hand-held applicator positioned above the target tissue. The magnetic pulses had a peak magnetic flux density of 4 tesla; 50 pulses were applied in 5 sec. Biphasic magnetic pulses were twice as effective as monophasic pulses and about equally effective as traditional electroporation pulses . Advantages of magnetopermeabilization over electoporation include: No contact between applicator and subject ("contact-less"); no need for invasive, disposable, sterile electrodes ("needle-less"); no pain from needles and reduced overall pain; no known side effects; easier and faster to administer than electroporation; less expensive due to absence of disposables; and, importantly, greater tissue penetration of the magnetic field allowing treatment of anatomical areas inaccessible by electroporation.

Piezoelectric permeabilization of mammalian dermal tissue for in vivo DNA delivery leads to enhanced protein expression and increased immunogenicity.

Electropermeabilization of mammalian cells is a technique that has been used for the delivery of therapeutics, such as DNA plasmids or DNA vaccines. Typically, delivery via electropermeabilization occurs through injection of the substance into the tissue of interest followed by the insertion of electrodes at the site and the application of brief electrical pulses. Here we detail a novel and innovative contactless electropermeabilization method to deliver DNA plasmids to dermal tissue in vivo. This process has the advantage of eliminating the insertion of additional needles that serve as electrodes to facilitate the application of electric pulses in conventional electroporation processes. Plasmid encoding GFP was injected into guinea pig skin and pulsed with the novel contactless electropermeabilization method. Three days following treatment, robust GFP expression was observed on the skin of pulsed animals. Strong humoral immune responses were also achieved when a DNA vaccine expressing the influenza antigen NP was delivered and pulsed using the novel device in comparison to naked injection alone. This delivery method has the advantage of being contactless and suggests that gene transfer via this mode warrants further development.

Dental therapists and dental hygienists educated for the New Zealand environment.

New Zealand has a long history of dental care provided by school dental nurses, now known as dental therapists. The nature of their training courses, although delivered in different centers, had remained relatively constant until 1999 when educational responsibility was transferred to the universities. Dental hygienists were not trained in New Zealand until 1994, with the exception of the New Zealand Army hygienists. Since 2001, the education of both dental therapists and dental hygienists has been the responsibility of the universities. Significant and progressive changes in educational delivery have occurred since then, which have culminated in three-year degree qualifications for dual-trained oral health professionals. Factors influencing this change included increased professionalism associated with the new legislative requirements for registration, workforce shortages, and enhanced educational and clinical practice requirements. The Bachelor of Oral Health degree at the University of Otago has an added emphasis on social sciences and incorporates aspects of learning relating to New Zealand's cultural heritage. We explore in this article the rationale for the introduction of a Bachelor of Oral Health in New Zealand and how it is designed to equip graduates as professionals in oral health.

Dental therapists: a global perspective.

In 1921, New Zealand began training school dental nurses, subsequently deploying them throughout the country in school-based clinics providing basic dental care for children. The concept of training dental nurses, later to be designated dental therapists, was adopted by other countries as a means of improving access to care, particularly for children. This paper profiles six countries that utilise dental therapists, with a description of the training that therapists receive in these countries, and the context in which they practice. Based on available demographic information, it also updates the number of dental therapists practising globally, as well as the countries in which they practice. In several countries, dental therapy is now being integrated with dental hygiene in training and practice to create a new type of professional complementary to a dentist. Increasingly, dental therapists are permitted to treat adults as well as children. The paper also describes the status of a current initiative to introduce dental therapy to the United States. It concludes by suggesting that dental therapists can become valued members of the dental team throughout the world, helping to improve access to care and reducing existing disparities in oral health.

Review of oral pathology service, Medlab Dental, University of Otago, 2002-2005.

The School of Dentistry of the University of Otago operates a diagnostic oral pathology service, Medlab Dental, as a joint venture with the private pathology service Medlab South. This report reviews the use of the service in 2005 and provides information on current activities that highlights the importance of oral pathology diagnostic services in patient management.

Learning in oral biology: a comparison between deep and surface approaches.

It has been suggested that students approach their learning in at least two qualitatively different ways. In the surface approach, students see tasks as being imposed, for which they develop coping strategies focused on reproduction of essentials and memorising information for assessment rather than for understanding. In the deep approach, students seek to understand ideas to allow them to relate and integrate knowledge from other parts of their study and thereby develop conceptual frameworks from which they can derive solutions to novel problems. To these two approaches, a third, achieving approach, is often added, in which students aim to obtain the highest grades, whether or not they grasp the learning material. In this study we used a subject-specified version of Biggs' Study Process Questionnaire to obtain data about the way dental and dental technology students perceived and approached their learning in oral biology. Questionnaires were distributed to 62 second-year dental students and 23 second-year dental technology students. Within each group the dependent variables examined were deep, surface or achieving approaches to learning. Analysis of these data showed that significant differences between dental and dental technology students centred on their approaches to learning. However, there were no significant differences attributable to gender, country of origin or ethnicity. While dental students, who had a relatively well developed understanding of the nature of their studies in oral biology at the start of their course, adopted deep learning strategies, dental technology students, who had had no prior experience of university education per se, were significantly more surface-orientated.

Surface-active fungicidal D-peptide inhibitors of the plasma membrane proton pump that block azole resistance.

A 1.8-million-member D-octapeptide combinatorial library was constructed in which each member comprised a diversity-containing N-terminal pentapeptide and a C-terminal amidated triarginine motif. The C-terminal motif concentrated the library members at the fungal cell surface. A primary screen for inhibitors of Saccharomyces cerevisiae and Candida albicans growth, together with an in vitro secondary screen with the S. cerevisiae plasma membrane ATPase (Pma1p) as a target, identified the antifungal D-octapeptide BM0 (D-NH(2)-RFWWFRRR-CONH(2)). Optimization of BM0 led to the construction of BM2 (D-NH(2)-RRRFWWFRRR-CONH(2)), which had broad-spectrum fungicidal activity against S. cerevisiae, Candida species, and Cryptococcus neoformans; bound strongly to the surfaces of fungal cells; inhibited the physiological activity of Pma1p; and appeared to target Pma1p, with 50% inhibitory concentrations in the range of 0.5 to 2.5 microM. At sub-MICs (<5 microM), BM2 chemosensitized to fluconazole (FLC) S. cerevisiae strains functionally hyperexpressing fungal lanosterol 14alpha-demethylase and resistance-conferring transporters of azole drugs. BM2 chemosensitized to FLC some FLC-resistant clinical isolates of C. albicans and C. dubliniensis and chemosensitized to itraconazole clinical isolates of C. krusei that are intrinsically resistant to FLC. The growth-inhibitory concentrations of BM2 did not cause fungal cell permeabilization, significant hemolysis of red blood cells, or the death of cultured HEp-2 epithelial cells. BM2 represents a novel class of broad-spectrum, surface-active, Pma1p-targeting fungicides which increases the potencies of azole drugs and circumvents azole resistance.

Context rich problems in oral biology teaching.

Problem-based learning (PBL) has now been introduced in at least one of its various taxonomic forms in most dental curricula. We recently developed a novel form of PBL, referred to as Context Rich Problems, which we implemented in the Oral Biology course at the Otago University Dental School. A unique event, the teaching of second and third year students in the same year, allowed us to evaluate CRPs in these two academic years simultaneously. Our findings showed that second year students were not as positive as more mature third year students in accepting the transition from a traditional didactic form of teaching to PBL. Both groups, however, found that CRPs significantly enhanced their learning experience and both groups found that they needed less time spent on preparation than they had expected. In some respects, such as previous exposure to the web and electronic media, non-New Zealanders had had a significantly higher exposure.