The effect of hypoxic-ischemic brain injury in perinatal rats on the abundance and proteolysis of brevican and NG2

Oligodendrocyte (OL) progenitor cells are particularly susceptible to perinatal hypoxia/ischemia (H-I) resulting in decreased myelination and attenuated development of white matter fiber tracts. Brevican is an aggregating chondroitin sulfate proteoglycan (CSPG) secreted by OLs and their progenitors prior to and during active developmental myelination whereas neuron-glia antigen 2 (NG2) is a transmembrane CSPG produced by early OL progenitors. Although both proteoglycans are associated with maturation of OLs, it is not known if they are altered by H-I brain injury in the neonate. We have therefore examined the time course of changes in brevican and NG2 abundance and proteolysis in the neonatal rat hippocampus after H-I. In a standard H-I model of unilateral carotid artery ligation and exposure to hypoxia, a cavitary infarct involving the ipsilateral parietal and temporal regions of cerebral cortex, hippocampus, and striatum of most rat pups was clearly evident 4 days after H-I. The abundance of total extractable brevican was markedly reduced in the ipsilateral hippocampus at 1 and 14 days after H-I (relative to the contralateral side). At these times, the total G1 proteolytic fragment of brevican was lower in the ipsilateral hippocampus and the level of a protease-generated brevican fragment was significantly diminished in the OL-rich hippocampal fimbria. Hippocampal NG2 levels were also lower at 1 and 4 days after H-I, but were not different from the contralateral side at 14 days. Since brevican, brevican G1 fragment, and NG2 loss occur around the time of progressive cell death and the appearance of the infarct, it may be that H-I rapidly induces a cellular response that actively depletes these proteoglycans from the hippocampal matrix. While the mechanism of this loss is unclear, it would appear to be an early event in the process that could be involved in apoptotic cell death and/or tissue injury.     

Proteases, extracellular matrix, and cancer: a workshop of the path B study section

The role of the extracellular matrix (ECM) in the tumor microenvironment is not limited to being a barrier against tumor invasion. The ECM is a reservoir of cell binding proteins and growth factors that affect tumor cell behavior. It is also substantially modified by proteases produced by tumor cells or stroma cells. As a result of the activity of these proteases, cell-cell and cell-ECM interactions are altered, new biologically active ECM molecules are generated, and the bioavailability and activity of many growth factors, growth factor receptors, and cytokines are modified. ECM-degrading proteases also play a critical role in angiogenesis, where they can act as positive as well as negative regulators of endothelial cell proliferation and vascular morphogenesis. This review article summarizes some of the most relevant findings made over the recent years that were discussed at a workshop organized by the Path B Study Section of the National Institutes of Health in October 2002.     

Orthodontics. Part 6: Risks in orthodontic treatment

Orthodontics has the potential to cause significant damage to hard and soft tissues. The most important aspect of orthodontic care is to have an extremely high standard of oral hygiene before and during orthodontic treatment. It is also essential that any carious lesions are dealt with before any active treatment starts. Root resorption is a common complication during orthodontic treatment but there is some evidence that once appliances are removed this resorption stops. Some of the risk pointers for root resorption are summarised. Soft tissue damage includes that caused by archwires but also the more harrowing potential for headgears to cause damage to eyes. It is essential that adequate safety measures are included with this type of treatment.     

Orthodontics. Part 5: Appliance choices

There are bewildering array of different orthodontic appliances. However, they fall into four main categories of removable, fixed, functional and extra-oral devices. The appliance has to be selected with care and used correctly as inappropriate use can make the malocclusion worse. Removable appliances are only capable of very simple movements whereas fixed appliances are sophisticated devices, which can precisely position the teeth. Functional appliances are useful in difficult cases and are primarily used for Class II Division I malocciusions. Extra-oral devices are used to re-enforce anchorage and can be an aid in both opening and closing spaces.     

Aoteaoroa/New Zealand nursing: from eugenics to cultural safety..

The concept of cultural safety offers a unique approach to nursing practice, based on recognition of the power differentials inherent in any interaction. It is from within the context of nursing in Aoteaoroa/New Zealand (A/NZ) that the concept developed and was subsequently integrated into nursing education. Cultural safety is based within a framework of biculturalism, and is congruent with the tenets of the nation's founding document, the Treaty of Waitangi. Clarification of the concept is offered, together with a review of the historical shift in nursing attitudes that has led to the emergence of "cultural safety" as a viable and valued component of nursing practice. The argument is made that cultural safety has allowed for a more reflective, critical understanding of the actions of nursing to develop. This includes recognition that nurses' attitudes and values have inevitably been influenced by social and political forces, and as such are in part reflective of those within the wider community. Comparison between the support given by nurses in the early 1900s to the theory of eugenics and the current acceptance of cultural safety is used to highlight this point. An examination of the literature identifies that ideological and conceptual changes have occurred in the approach of A/NZ nurses to issues with cultural implications for practice. A review of background factors relating to Maori health status and the Treaty of Waitangi is presented as a necessary context to the overall discussion. The discussion concludes with an acknowledgement that while the rhetoric of cultural safety is now part of nursing culture in New Zealand, there is no firm evidence to evaluate its impact in practice. Issues identified as impacting on the ability to assess/research a concept, such as cultural safety, are discussed. For cultural safety to become recognised as a credible (and indispensable) tool, it is necessary to further examine the "end-point" or "outcomes" of the process.     

Computed tomography colonography: feasibility of computer-aided polyp detection in a "first reader" paradigm

OBJECTIVE:: To determine the feasibility of a computer-aided detection (CAD) algorithm as the "first reader" in computed tomography colonography (CTC). METHODS:: In phase 1 of a 2-part blind trial, we measured the performance of 3 radiologists reading 41 CTC studies without CAD. In phase 2, readers interpreted the same cases using a CAD list of 30 potential polyps. RESULTS:: Unassisted readers detected, on average, 63% of polyps > or =10 mm in diameter. Using CAD, the sensitivity was 74% (not statistically different). Per-patient analysis showed a trend toward increased sensitivity for polyps > or =10 mm in diameter, from 73% to 90% with CAD (not significant) without decreasing specificity. Computer-aided detection significantly decreased interobserver variability (P = 0.017). Average time to detection of the first polyp decreased significantly with CAD, whereas total reading case reading time was unchanged. CONCLUSION:: Computer-aided detection as a first reader in CTC was associated with similar per-polyp and per-patient detection sensitivity to unassisted reading. Computer-aided detection decreased interobserver variability and reduced the time required to detect the first polyp.