Innovation in dental education: The "On-the-Fly" approach to simultaneous development, implementation and evidence collection.

INTRODUCTION: This study outlines an approach for education innovation and addresses the ambivalence between evidence-based and non-evidence-based conditions. The "on-the-fly" approach was described as involving implementation during the development of an innovation for dental education. MATERIALS AND METHODS: The process of designing and implementing cutting-edge technology of the MOOG Simodont Dental Trainer (DT) whilst systematically collecting evidence illustrates the "on-the-fly" approach. RESULTS: Using the "on-the-fly" approach for developing, implementing and collecting evidence simultaneously in an academic environment appears feasible in serving both the professionals, users and developers and system designers. During the implementation of the new technology, growing evidence stepwise strengthened its position; therefore, showing stakeholders that evidence was used to improve the technology seemed to support and increase acceptance of the new technology. CONCLUSIONS: When pioneering an innovative technology in a specialty field, the development stage often precedes evidence for its effectiveness. Consciously choosing the "on-the-fly" approach clarifies to stakeholders in advance about the lack of evidence in an innovation and the need of their support to collect such evidence for improvement and in order to facilitate implementation.

Expression of a linear Sry transcript in the mouse genital ridge.

Sry is the Y-chromosomal gene that is pivotal in the determination of sex in mammals, however the structure of the Sry transcript produced in the embryo has not been determined. We show here that the transcript expressed in the developing mouse gonad at the sex determining stage of development is linear, polyadenylated and encoded by a single exon, in contrast to the circular, apparently untranslated transcript produced in adult testes. The linear transcript was not detected in any other fetal tissue nor in any adult tissue tested, and was expressed only in the genital ridge portion of the urogenital ridge. The spatial and temporal profile of Sry expression suggests that its role in the mouse fetus is limited to initiating Sertoli cell development during testis determination.

Sry requires a CAG repeat domain for male sex determination in Mus musculus.

SRY, the mammalian Y-chromosomal sex-determining gene, encodes a protein characterized by a DNA-binding and -bending domain referred to as the HMG box. Despite the pivotal role of this gene, only the HMG box region has been conserved through evolution, suggesting that SRY function depends solely on the HMG box and therefore acts as an architectural transcription factor. In mice (genus Mus) Sry also includes a large CAG trinucleotide repeat region encoding a carboxy-terminal glutamine-rich domain that acts as a transcriptional trans-activator in vitro. The absence of this or any other potential trans-activating domain in other mammals, however, has raised doubts as to its biological relevance. To test directly whether the glutamine-rich region is required for Sry function in vivo, we created truncation mutations of the Mus musculus musculus Sry gene and tested their ability to induce testis formation in XX embryos using a transgenic mouse assay. Sry constructs that encode proteins lacking the glutamine-rich region were unable to effect male sex determination, in contrast to their wild-type counterparts. We conclude that the glutamine-rich repeat domain of the mouse Sry protein has an essential role in sex determination in vivo, and that Sry may act via a fundamentally different biochemical mechanism in mice compared with other mammals.

Mutations in Sox18 underlie cardiovascular and hair follicle defects in ragged mice.

Analysis of classical mouse mutations has been useful in the identification and study of many genes. We previously mapped Sox18, encoding an SRY-related transcription factor, to distal mouse chromosome 2. This region contains a known mouse mutation, ragged (Ra), that affects the coat and vasculature. Here we have directly evaluated Sox18 as a candidate for Ra. We found that Sox18 is expressed in the developing vascular endothelium and hair follicles in mouse embryos. Furthermore, we found no recombination between Sox18 and Ra in an interspecific backcross segregating for the Ra phenotype. We found point mutations in Sox18 in two different Ra alleles that result in missense translation and premature truncation of the encoded protein. Fusion proteins containing these mutations lack the ability to activate transcription relative to wild-type controls in an in vitro assay. Our observations implicate mutations in Sox18 as the underlying cause of the Ra phenotype, and identify Sox18 as a critical gene for cardiovascular and hair follicle formation.

Widespread expression of the testis-determining gene SRY in a marsupial.

There is compelling evidence from mutation analysis and transgenesis that the SRY gene isolated from human and mouse encodes the testis-determining factor on the mammalian Y chromosome. However, how SRY achieves this function is unclear. Although marsupials have been separated from eutherian mammals for approximately 100 million years, homologues of SRY have been localised to the Y chromosome of two unrelated marsupial species, the tammar wallaby and the Darling Downs dunnart. Gonadal development is fundamentally similar in eutherian and marsupial mammals, but the timing of morphological events is different. Fetal Sry transcripts are confined to somatic cells of the male mouse genital ridge between 10.5-12.5 days post coitum, corresponding with the onset of testis differentiation. Analysis of Sry gene expression in the genital ridge of normal and germ cell-deficient fetal mice has established that this gene acts in the somatic cell lineage, and is presumed to induce the formation of Sertoli cells. This assumption can be tested more critically in the tammar, where the equivalent stages of testis differentiation are observed over a 7-day period. We have examined the relationship of SRY expression to testis differentiation in the tammar wallaby. We show the marsupial SRY gene cannot be exclusively coupled to Sertoli cell differentiation, as this gene is expressed in the male fetus from several days before genital ridge formation until 40 days after birth. SRY transcripts are also present in a variety of extra-gonadal tissues in the developing young and adult male, a pattern of SRY expression similar to that observed in humans. These data indicate that, in addition to a role in testis determination, SRY may have other functions [corrected].

An H-YDb epitope is encoded by a novel mouse Y chromosome gene.

Rejection of male tissue grafts by genotypically identical female mice has been explained by the existence of a male-specific transplantation antigen, H-Y (ref. 1), but the molecular nature of H-Y antigen has remained obscure. Hya, the murine locus controlling H-Y expression, has been localized to delta Sxrb, a deletion interval of the short arm of the Y chromosome. In mice, H-Y antigen comprises at least four distinct epitopes, each recognized by a specific T lymphocyte clone. It has recently been shown that one of these epitopes, H-YKk, is a peptide encoded by the Y-linked Smcy gene, presented at the cell surface with the H-2Kk major histocompatibility complex (MHC) molecule. However, deletion mapping and the analysis of variable inactivation of H-Y epitopes has suggested that the Hya locus may be genetically complex. Here we describe a novel mouse Y chromosome gene which we call Uty (ubiquitously transcribed tetratricopeptide repeat gene on the Y chromosome). We identify the peptide WMHHNMDLI derived from the UTY protein as an H-Y epitope, H-YDb. Our data formally demonstrate that H-Y antigen is the product of more than one gene on the Y chromosome.

The Sry-related gene Sox9 is expressed during chondrogenesis in mouse embryos.

Mutations in the human SRY-related gene, SOX9, located on chromosome 17, have recently been associated with the sex reversal and skeletal dysmorphology syndrome, campomelic dysplasia. In order to clarify the role of this gene in skeletal development, we have studied the expression of mouse Sox9 during embryogenesis. Sox9 is expressed predominantly in mesenchymal condensations throughout the embryo before and during the deposition of cartilage, consistent with a primary role in skeletal formation. Interspecific backcross mapping has localized mouse Sox9 to distal chromosome 11. The expression pattern and chromosomal location of Sox9 suggest that it may be the gene defective in the mouse skeletal mutant Tail-short, a potential animal model for campomelic dysplasia.

SOX9 directly regulates the type-II collagen gene.

Mutations in human SOX9 are associated with campomelic dysplasia (CD), characterised by skeletal malformation and XY sex reversal. During chondrogenesis in the mouse, Sox9 is co-expressed with Col2a1, the gene encoding type-II collagen, the major cartilage matrix protein. Col2a1 is therefore a candidate regulatory target of SOX9. Regulatory sequences required for chondrocyte-specific expression of the type-II collagen gene have been localized to conserved sequences in the first intron in rats, mice and humans. We show here that SOX9 protein binds specifically to sequences in the first intron of human COL2A1. Mutation of these sequences abolishes SOX9 binding and chondrocyte-specific expression of a COL2A1-driven reporter gene (COL2A1-lacZ) in transgenic mice. Furthermore, ectopic expression of Sox9 trans-activates both a COL2A1-driven reporter gene and the endogenous Col2a1 gene in transgenic mice. These results demonstrate that COL2A1 expression is directly regulated by SOX9 protein in vivo and implicate abnormal regulation of COL2A1 during, chondrogenesis as a cause of the skeletal abnormalities associated with campomelic dysplasia.

[Innovations in education for the digital student]. / Onderwijsinnovaties voor de digitale student.

A significant percentage of today's teaching staff received their professional training before the revolution in information and communication technology took place. Students, by contrast, are so-called 'digital natives': they grew up surrounded by digital technology. Present day students are used to multi-tasking and expect to be facilitated in using educationalfacilities regardless of time and place. Adapting higher education to present day students' study behaviour and expectations requires reconsideration of educationalform and methods. Several types of staff can be distinguished in their attitude towards technological innovation in education. Among them are staff who are reluctant in accepting innovations. Dental schools face the challenge of finding supportfor innovations with all their teaching staff and to better adapt to the twenty-first century student. In order to introduce technological innovations successfully, students need to become involved and sufficient attention must be paid to qualifying instructors.

The delicate balance between male and female sex determining pathways: potential for disruption of early steps in sexual development.

Testes and ovaries develop from the same primordial structures, the genital ridges, in the mammalian foetus. Male development depends critically on the correct functioning of the Y-linked testis-determining gene, Sry. However, Sry is highly vulnerable to mutation, and so does not provide a very robust sex-determining mechanism. Both in testes and in ovaries, proper gonadal development involves co-ordinated regulation of the bipotential fates of a number of different cell lineages, and is dependent on intercellular signalling mechanisms. If either the testicular or ovarian pathway stalls in the early stages, mechanisms operate to engage the alternative pathway. For these reasons, the early steps in mammalian sexual development are vulnerable to genetic and environmental perturbation, and represent possible points of action of endocrine disrupting compounds.

Testis-determining factor and Y-linked sex reversal.

A gene named SRY, isolated last year from the sex-determining region of the human Y chromosome, satisfies many of the criteria expected of the testis-determining factor gene. Mutations in SRY have been found in XY females, strongly implicating SRY as the testis-determining gene.

[Is there a future for administrative psychiatry?]. / Heeft beleidspsychiatrie toekomst?

The role of the psychiatrist as administrator was first defined in the psychiatrist profile of the Dutch Psychiatric Association (1996). According to that profile the psychiatrist was the 'playing captain' of a multidisciplinary team. However, this phraseology was no longer used in the revised profile (2005); there the psychiatrist had become primarily a medical specialist. As a result of the broad acceptance of the Canmeds competence-based training, the management of psychiatry has now become one of the seven core skills of the psychiatric profession. Competence-based training in the future will put more emphasis on management skills, the psychiatrist will once more become a 'playing captain' and there will again be a future for administrative psychiatry.

Gonad development: signals for sex.

The formation of testes or ovaries in the mammalian embryo is critical in determining sexual identity and the ability to reproduce. Recent studies have begun to illuminate the cellular signalling events required for development of functional testes.

The ZFY gene family in humans and mice.

For several years, ZFY (zinc finger gene on the Y chromosome) was considered the best candidate for the human testis-determining gene TDF. This gene and its close relatives have been intensely studied in the hope of understanding the molecular biology of sex determination, particularly in humans and mice. Now that there is overwhelming evidence that ZFY and TDF are distinct loci, we are left with a large body of data, and a question: what do these genes really do?

Mice null for sox18 are viable and display a mild coat defect.

We have previously shown that Sox18 is expressed in developing vascular endothelium and hair follicles during mouse embryogenesis and that point mutations in Sox18 are the underlying cause of cardiovascular and hair follicle defects in ragged (Ra) mice. Here we describe the analysis of Sox18(-/-) mice produced by gene targeting. Despite the profound defects seen in Ra mice, Sox18(-/-) mice have no obvious cardiovascular defects and only a mild coat defect with a reduced proportion of zigzag hairs. A reduction in the amount of pheomelanin pigmentation in hair shafts was also observed; later-forming hair follicles showed a reduced subapical pheomelanin band, giving Sox18(-/-) mice a slightly darker appearance than Sox18(+/+) and Sox18(+/-) siblings. Sox18(-/-) mice are viable and fertile and show no difference in the ability to thrive relative to littermates. Because of the mild effect of the mutation on the phenotype of Sox18(-/-) mice, we conclude that the semidominant nature of the Ra mutations is due to a trans-dominant negative effect mediated by the mutant SOX18 proteins rather than haploinsufficiency as has been observed for other SOX genes. Due to the similarity of SOX18 to other subgroup F SOX proteins, SOX7 and -17, and the overlap in expression of these genes, functional redundancy amongst these SOX proteins could also account for the mild phenotype of Sox18(-/-) mice.

Cloning and characterisation of the Sry-related transcription factor gene Sox8.

SOX proteins form a large family of transcription factors related by a DNA-binding domain known as the HMG box. Some 30 Sox genes have been identified in mammals and orthologues have been found in a wide range of other metazoans. Sox genes are highly conserved and are known to play important roles in embryonic development, including roles in gonadal, central nervous system, neural crest and skeletal development. Several SOX genes have been implicated in human congenital diseases. We report here the isolation of Sox8 and its characterisation in mice and humans. This gene has a remarkably similar primary structure and genomic organisation to the campomelic dysplasia gene SOX9 and the Waardenburg-Shah syndrome gene SOX10. SOX8 protein is able to bind to canonical SOX target DNA sequences and activate transcription in vitro through two separate trans -activation regions. Further, Sox8 is expressed in the central nervous system, limbs, kidneys, gonads and craniofacial structures during mouse embryo development. Sox8 maps to the t complex on mouse chromosome 17 and to human chromosome 16p13.3, a region associated with the microphthalmia-cataract syndrome CATM and the alpha-thalassemia/mental retardation syndrome ATR-16.

Mammalian sex-determining genes.

The recent cloning of the Y-linked sex-determining gene SRY has ended one of the most notorious gene hunts in mammalian molecular genetics. Attention has now been turned to characterizing this gene further and studying how it acts as a switch in the choice of male or female developmental pathways.

SOX18 and the transcriptional regulation of blood vessel development.

SOX18 is a transcription factor that is transiently expressed in nascent endothelial cells during embryonic development and adult neovascularization. This protein belongs to the SOX family of transcription factors, which are proving to be some of the key regulators of cell-type specification in the vertebrate embryo. Natural mutations in the Sox18 gene have been shown to result in cardiovascular dysfunction, in some cases leading to death. Available evidence thus implicates Sox18 as an important regulator of vascular development, most likely playing a key role in endothelial cell specification. However, the genetic knockout of Sox18 in mice has produced a confounding result that complicates our understanding of the molecular mode of action of the SOX18 protein. We speculate that Sox18 may act in a redundant fashion with closely related genes such as Sox7 and/or Sox17.