Effects of clinical experience and explorer type on judged crown margin acceptability

PURPOSE

This study was undertaken to simultaneously compare instrumentation type and operator characteristics in judgments of clinical acceptability of crowns exhibiting a controlled range of marginal gaps. The research was conducted in a laboratory setting and generalizability analysis was used as a statistical technique to identify the sources contributing to variation in the judgment outcome.

MATERIALS AND METHODS

A crown was seated on an ivorine tooth in a device that permitted continuous adjustment in intervals of 25 mum to produce known marginal gaps ranging from zero to 250 microm. Forty-nine students and six faculty members used five types of explorers each to determine, by tactile examination, the point on the controlled increasing marginal gap where they would no longer regard the gap as clinically acceptable.

RESULTS

There were no differences across type of explorer. Operators with clinical experience had a threshold that rejected crowns at a smaller gap than did those operators without clinical experience (p= 0.007). Faculty members maintained a higher individual degree of consistency in their personal judgments than did students (p= 0.02); however, the inter-operator consistency was significantly lower for faculty members than for students (p < 0.05).

CONCLUSIONS

Differences among operators in a simulation of the decision regarding gaps in crowns accounted for 63% of the variance; type of explorer used in assisting this decision accounted for about half as much variance. Faculty members making such judgments exhibited high intra-operator consistency but significantly lower inter-operator consistency than did students. The study suggests that the internal standards dentists use for clinical decision making deserves further study as they may be as significant as the equipment used.

Pulp Capping with Mineral Trioxide Aggregate (MTA): A Retrospective Analysis of Carious Pulp Exposures Treated by Undergraduate Dental Students

Carious pulp exposures present a therapeutic challenge for clinicians. Mineral trioxide aggregate (MTA) is a treatment option that may provide successful outcomes for the capping of carious pulp exposures in adult patients. However, the success measured as pulp survival over a period of one and two years of pulp caps performed by undergraduate dental students may be low. This study provides data regarding the impact of exposure sizes and other pre-operative variables on outcomes of MTA pulp caps in adults.

Use of non-randomised evidence alongside randomised trials in a systematic review of endovascular aneurysm repair: strengths and limitations

OBJECTIVE

To assess whether limitations of randomised controlled trials (RCTs) of endovascular aneurysm repair (EVAR) can be addressed by evidence from non-randomised studies.

DESIGN

Analysis of data from a systematic review.

METHODS

We conducted a review of EVAR versus open repair or non-surgical management of abdominal aortic aneurysms. In addition to RCTs, we included pre-specified registries of EVAR and open repair.

RESULTS

The six included RCTs randomised patients in 2003 and earlier. Of the three registries included, one contributed data on a large (>8000) sample of patients treated with newer generation EVAR devices and followed up for up to 8 years. However, treatment dates of these patients overlapped with those of the RCTs. The other registries were of limited usefulness. A large (>45,000) controlled observational study published while the review was in progress broadly supported the findings of RCTs comparing EVAR with open surgery. A comparison of outcomes across all studies did not support the hypothesis that the findings of the RCTs are no longer representative of clinical practice.

CONCLUSIONS

Both randomised and non-randomised sources of evidence have strengths and weaknesses for assessing the effectiveness of EVAR. Further research should explore the optimum use of registry data, including patient-level analyses.

An assessment of clinical predictors of intracranial head injury identified by computed tomography scan

A prospective study was done during a six-month period on 104 consecutive patients who were seen at the Accident and Emergency (A&E) Department of the UHWI and referred for CT scans of the head within 24 hours of sustaining head injuries. There were 74 (71.1%) males and 30 (28.8%) females. The mean age for females was 40.6 years and 32.4 years for males. Patients were clinically assessed for the presence or absence of vomiting, amnesia, loss of consciousness, bleeding of ear, nose and throat (ENT) and Glasgow Coma score (GCS). Negative predictive values were calculated for each parameter individually as well as the combination of all five. The absence of vomiting, amnesia, "loss of consciousness" (LOC) or ENT bleed had negative predictive values of 68%, 73%, 76% and 61.6% respectively. An assessment of Glasgow Coma Scale (GCS) of 15 had a 77.5% negative predictive value. When the history was indeterminate, the negative predictive values were 19%, 25%, 60% and 18% respectively for vomiting, amnesia, LOC and ENT bleed. When all four clinical indicators were absent in the history and examination and the GCS score 15, the negative predictive value for intracranial injury was 89.4%. In summary, the clinical indicators reviewed, alone or in combination, cannot exclude the presence of intracranial injury.

Rhombomere-specific analysis reveals the repertoire of genetic cues expressed across the developing hindbrain

Background

The Hox family of homeodomain transcription factors comprises pivotal regulators of cell specification and identity during animal development. However, despite their well-defined roles in the establishment of anteroposterior pattern and considerable research into their mechanism of action, relatively few target genes have been identified in the downstream regulatory network. We have sought to investigate this issue, focussing on the developing hindbrain and the cranial motor neurons that arise from this region. The reiterated anteroposterior compartments of the developing hindbrain (rhombomeres (r)) are normally patterned by the combinatorial action of distinct Hox genes. Alteration in the normal pattern of Hox cues in this region results in a transformation of cellular identity to match the remaining Hox profile, similar to that observed in Drosophila homeotic transformations.

Results

To define the repertoire of genes regulated in each rhombomere, we have analysed the transcriptome of each rhombomere from wild-type mouse embryos and not those where pattern is perturbed by gain or loss of Hox gene function. Using microarray and bioinformatic methodologies in conjunction with other confirmatory techniques, we report here a detailed and comprehensive set of potential Hox target genes in r2, r3, r4 and r5. We have demonstrated that the data produced are both fully reflective and predictive of rhombomere identity and, thus, may represent some the of Hox targets. These data have been interrogated to generate a list of candidate genes whose function may contribute to the generation of neuronal subtypes characteristic of each rhombomere. Interestingly, the data can also be classified into genetic motifs that are predicted by the specific combinations of Hox genes and other regulators of hindbrain anteroposterior identity. The sets of genes described in each or combinations of rhombomeres span a wide functional range and suggest that the Hox genes, as well as other regulatory inputs, exert their influence across the full spectrum of molecular machinery.

Conclusion

We have performed a systematic survey of the transcriptional status of individual segments of the developing mouse hindbrain and identified hundreds of previously undescribed genes expressed in this region. The functional range of the potential candidate effectors or upstream modulators of Hox activity suggest multiple unexplored mechanisms. In particular, we present evidence of a potential new retinoic acid signalling system in ventral r4 and propose a model for the refinement of identity in this region. Furthermore, the rhombomeres demonstrate a molecular relationship to each other that is consistent with known observations about neurogenesis in the hindbrain. These findings give the first genome-wide insight into the complexity of gene expression during patterning of the developing hindbrain.

Implementation research in mental health services: an emerging science with conceptual, methodological, and training challenges

One of the most critical issues in mental health services research is the gap between what is known about effective treatment and what is provided to consumers in routine care. Concerted efforts are required to advance implementation science and produce skilled implementation researchers. This paper seeks to advance implementation science in mental health services by over viewing the emergence of implementation as an issue for research, by addressing key issues of language and conceptualization, by presenting a heuristic skeleton model for the study of implementation processes, and by identifying the implications for research and training in this emerging field.

Implementation research in mental health services: an emerging science with conceptual, methodological, and training challenges

One of the most critical issues in mental health services research is the gap between what is known about effective treatment and what is provided to consumers in routine care. Concerted efforts are required to advance implementation science and produce skilled implementation researchers. This paper seeks to advance implementation science in mental health services by over viewing the emergence of implementation as an issue for research, by addressing key issues of language and conceptualization, by presenting a heuristic skeleton model for the study of implementation processes, and by identifying the implications for research and training in this emerging field.

Risk factors for chronic fatigue syndrome/myalgic encephalomyelitis: a systematic scoping review of multiple predictor studies

BACKGROUND

The aetiology of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is still unknown. The identification of risk factors for CFS/ME is of great importance to practitioners.

METHOD

A systematic scoping review was conducted to locate studies that analysed risk factors for CFS/ME using multiple predictors. We searched for published and unpublished literature in 11 electronic databases, reference lists of retrieved articles and guideline stakeholder submissions in conjunction with the development of a forthcoming national UK guideline. Risk factors and findings were extracted in a concise tabular overview and studies synthesized narratively.

RESULTS

Eleven studies were identified that met inclusion criteria: two case-control studies, four cohort studies, three studies combining a cohort with a case-control study design, one case-control and twin study and one cross-sectional survey. The studies looked at a variety of demographic, medical, psychological, social and environmental factors to predict the development of CFS/ME. The existing body of evidence is characterized by factors that were analysed in several studies but without replication of a significant association in more than two studies, and by studies demonstrating significant associations of specific factors that were not assessed in other studies. None of the identified factors appear suitable for the timely identification of patients at risk of developing CFS/ME within clinical practice.

CONCLUSIONS

Various potential risk factors for the development of CFS/ME have been assessed but definitive evidence that appears meaningful for clinicians is lacking.

Meta-analysis of nebulized amphotericin B to prevent or treat pulmonary aspergillosis in immunosuppressed animals

OBJECTIVES

Pulmonary aspergillosis in immunosuppressed patients is associated with significant mortality and morbidity. We assessed the prophylactic and therapeutic effect of nebulized amphotericin B (AmB) on mortality of immunosuppressed animals with pulmonary aspergillosis in this meta-analysis.

METHODS

Literature search was based on MEDLINE (1966 to January 15, 2007), EMBASE, and Cochrane-Controlled Trials Register (2006 issue 4) databases. Only randomized-controlled studies comparing nebulized AmB with placebo on immunosuppressed animals were included. Two reviewers reviewed and extracted the data independently.

RESULTS

Eight studies including 839 immunosuppressed animals were considered. The overall mortality of the immunosuppressed animals with pulmonary aspergillosis treated with nebulized AmB was reduced (69.4% versus 87.7%, odds ratio [OR] 0.12, 95% confidence interval [CI]: 0.08-0.19; P < 0.0001). The effect of nebulized AmB on mortality was more significant when the drug was administered as prophylaxis before the inoculation of Aspergillus fumigatus (OR 0.07, 95% CI: 0.03-0.12, P = 0.0001; I(2) = 0) than as a therapeutic agent (OR 0.20, 95% CI: 0.11-0.36, P < 0.0001; I(2) = 0) (ratio of the 2 ORs = 2.86, 95% CI: 1.03-6.11; P = 0.04). The effectiveness of AmB desoxycholate (OR 0.16, 0.06-0.38, P < 0.0001; I(2) = 0) and lipid-associated (liposomal, or lipid complex or colloidal dispersion) amphotericin (OR 0.11, 95% CI: 0.06-0.20, P < 0.0001; I(2) = 0) was not significantly different (ratio of the 2 ORs = 1.46, 95% CI: 0.49-4.39; P = 0.50). Three studies evaluated the potential side effects of nebulized amphotericin and showed that there was no significant renal toxicity but the amphotericin desoxycholate had some detrimental effects on pulmonary surfactant function.

CONCLUSIONS

The use of nebulized amphotericin, either as a prophylactic or therapeutic agent, is effective in reducing mortality of immunosuppressed animals with pulmonary aspergillosis. A large randomized controlled trial is needed to confirm whether combining nebulized amphotericin with systemic antifungal agents will reduce mortality in immunosuppressed patients with suspected or proven pulmonary aspergillosis.

Tissue interactions in the developing chick diencephalon

Background

The developing vertebrate brain is patterned first by global signalling gradients that define crude anteroposterior and dorsoventral coordinates, and subsequently by local signalling centres (organisers) that refine cell fate assignment within pre-patterned regions. The interface between the prethalamus and the thalamus, the zona limitans intrathalamica (ZLI), is one such local signalling centre that is essential for the establishment of these major diencephalic subdivisions by secreting the signalling factor Sonic hedgehog. Various models for ZLI formation have been proposed, but a thorough understanding of how this important local organiser is established is lacking.

Results

Here, we describe tissue explant experiments in chick embryos aimed at characterising the roles of different forebrain areas in ZLI formation. We found that: the ZLI becomes specified unexpectedly early; flanking regions are required for its characteristic morphogenesis; ZLI induction can occur independently from ventral tissues; interaction between any prechordal and epichordal neuroepithelial tissue anterior to the midbrain-hindbrain boundary is able to generate a ZLI; and signals from the dorsal diencephalon antagonise ZLI formation. We further show that a localised source of retinoic acid in the dorsal diencephalon is a likely candidate to mediate this inhibitory signal.

Conclusion

Our results are consistent with a model where planar, rather than vertical, signals position the ZLI at early stages of neural development and they implicate retinoic acid as a novel molecular cue that determines its dorsoventral extent.

RALDH-independent generation of retinoic acid during vertebrate embryogenesis by CYP1B1

Several independent lines of evidence have revealed an instructive role for retinoic acid (RA) signalling in the establishment of normal pattern and cellular specification of the vertebrate embryo. Molecular analyses have previously identified the major RA-synthesising (RALDH1-3) and RA-degrading (CYP26A-C1) enzymes as well as other components involved in RA processing (e.g. CRABP). Although the majority of the early effects of RA can be attributed to the activity of RALDH2, many other effects are suggestive of the presence of an as yet unidentified RA source. Here we describe the identification, expression, biochemistry and functional analysis of CYP1B1, a member of the cytochrome p450 family of mono-oxygenases, and provide evidence that it contributes to RA synthesis during embryonic patterning. We present in vitro biochemical data demonstrating that this enzyme can generate both all-trans-retinal (t-RAL) and all-trans-retinoic acid (t-RA) from the precursor all-trans-retinol (t-ROH), but unlike the CYP26s, CYP1B1 cannot degrade t-RA. In particular, we focussed on the capacity of CYP1B1 to regulate the molecular mechanisms associated with dorsoventral patterning of the neural tube and acquisition of motor neuron progenitor domain identity. Concordant with its sites of expression and biochemistry, data are presented demonstrating that CYP1B1 is capable of eliciting responses that are consistent with the production of RA. Taken together, we propose that these data provide strong support for CYP1B1 being one of the RALDH-independent components by which embryos direct RA-mediated patterning.

Radiation transfer effects on the spectra of laser-generated plasmas

Experimental x-ray spectra of the H-like 2p --> 1s (Lyman-alpha) doublet have been obtained using time-integrated high-resolution spectroscopy of a constrained-flow, laser-generated aluminum plasma. These spectra show monotonic alteration of the relative intensities of the doublet components with distance from the target surface. Excellent agreement between experiment and theory is found only if the modeling includes both ion collisional rates between the fine-structure components of the level and, more importantly, the radiative pumping of one Lyman-alpha component by the other component along the direction of the major velocity gradient (i.e., perpendicular to the direction of spectra observation). Understanding radiation transfer in plasmas with high velocity gradients is important in modeling many astrophysical objects, and this experiment acts as a benchmark for such complex calculations.

Factors associated with infection by Pseudomonas aeruginosa in adult cystic fibrosis

Cross-infection with Pseudomonas aeruginosa is an emerging issue in the care of patients with cystic fibrosis (CF). This study sought to determine the extent of, and patient factors associated with, cross-infection in a tertiary referral adult CF centre. P. aeruginosa isolates were genotyped into two groups between November 2001 and February 2003, using pulsed-field gel electrophoresis after DNA digestion by the SpeI endonuclease, and identified as clustered if there was >80% homology in the macrorestriction profiles. Patient factors and measures of disease severity were identified a priori. In total, 157 out of 227 patients had a P. aeruginosa isolate genotyped. Of these, 94 patients (60%) were infected with clustered genotypes and 47 (30%) were infected with the newly described "Midlands 1" (Md1) genotype. A further 18 patients were infected with the previously identified "Liverpool" genotype and two with the "Manchester" genotype. Logistic regression analysis revealed that the predominant predictor of infection with Md1 was age at the time of referral to the centre, suggesting that infection may have occurred prior to referral in some patients. Md1 demonstrated a relatively benign anti-biogram and did not appear to be associated with more severe disease. In conclusion, the present study provides further evidence of the emerging importance of Pseudomonas aeruginosa cross-infection in cystic fibrosis.

A high throughput messenger RNA differential display screen identifies discrete domains of gene expression and novel patterning processes along the developing neural tube

BACKGROUND

During early development the vertebrate neural tube is broadly organized into the forebrain, midbrain, hindbrain and spinal cord regions. Each of these embryonic zones is patterned by a combination of genetic pathways and the influences of local signaling centres. However, it is clear that much remains to be learned about the complete set of molecular cues that are employed to establish the identity and intrinsic neuronal diversity of these territories. In order to address this, we performed a high-resolution messenger RNA differential display screen to identify molecules whose expression is regionally restricted along the anteroposterior (AP) neuraxis during early chick development, with particular focus on the midbrain and hindbrain vesicles.

RESULTS

This approach identified 44 different genes, with both known and unknown functions, whose transcription is differentially regulated along the AP axis. The identity and ontological classification of these genes is presented. The wide variety of functional classes of transcripts isolated in this screen reflects the diverse spectrum of known influences operating across these embryonic regions. Of these 44 genes, several have been selected for detailed in situ hybridization analysis to validate the screen and accurately define the expression domains. Many of the identified cDNAs showed no identity to the current databases of known or predicted genes or ESTs. Others represent genes whose embryonic expression has not been previously reported. Expression studies confirmed the predictions of the primary differential display data. Moreover, the nature of identified genes, not previously associated with regionalisation of the brain, identifies novel potential mechanisms in that process.

CONCLUSION

This study provides an insight into some of the varied and novel molecular networks that operate during the regionalization of embryonic neural tissue and expands our knowledge of molecular repertoire used during development.