Ethical dilemmas confronting dentists in Queensland, Australia

Background: This paper details contemporary ethical dilemmas encountered by Queensland dentists. Methods: An age-stratified sample of 499 dentists resident in Queensland was surveyed. The questionnaire contained scenarios of five common ethical dilemmas. In addition, open-ended questions sought the respondent's most frequent, difficult and recent ethical dilemmas, and where they would seek guidance in dealing with ethical problems. Results: Respondents acknowledged the patient's rights in treatment decisions and the dentist's right to refuse demands for inappropriate treatment. However, responses varied in the extent to which dentists may influence treatment decisions. Few respondents would ignore evidence of poor dental treatment but they are evenly divided in choosing to inform the patient, the dentist or both. Poor quality treatment is the most frequent and difficult dilemma, and half have experienced this problem recently. Requests by patients for fraudulent receipts occur in a third of responses. Dentists develop ethical values from multiple sources but for help with dental ethical problems, 90 per cent of respondents would consult another dentist. Conclusions: Of the ethical dilemmas discussed in this survey, those relating to poor quality treatment confronted most respondents. Also the actions of dentists in dealing with these dilemmas were most varied.

Breeding dynamics of koalas in open woodlands

The spatial and breeding dynamics of koalas in sub-tropical woodlands at Blair Athol in central Queensland were intensively monitored between 1993 and 1998. Genetic relationships among koalas at this locality were studied to determine the breeding dynamics of males, including whether 'resident' or 'transient' males dominate as sires. Males and females were radio-collared and tracked periodically throughout each year of the study. Genotypes from hypervariable microsatellite loci identified uniquely all individuals and were used to analyse parentage as well as to determine population genetic parameters when compared with other regional localities. Koalas at Blair Athol comprise a population in genetic equilibrium. Gene diversity estimates show the population to be similar to other populations found in similar habitat in the region, and estimates of genetic differentiation among four regional populations showed that gene flow conforms to a model of isolation by distance. Analysis of parentage found that both resident and transient males sired about equal numbers of offspring. Familial DNA analysis revealed multiple paternities of successive young in this population. The conclusion from this study is that 'resident' status among males does not confer any advantage for parentage.

An inverse design of an open, head/neck RF coil for MRI

Radio-frequency (RF) coils are a necessary component of magnetic resonance imaging (MRI) systems. When used in transmit operation, they act to generate a homogeneous RF magnetic field within a volume of interest and when in receive operation, they act to receive the nuclear magnetic resonance signal from the RF-excited specimen. This paper outlines a procedure for the design of open RF coils using the time-harmonic inverse method. This method entails the calculation of an ideal current density on a multipaned planar surface that would generate a specified magnetic field within the volume of interest. Because of the averaging effect of the regularization technique in the matrix solution, the specified magnetic field is shaped within an iterative procedure until the generated magnetic field matches the desired magnetic field. The stream-function technique is used to ascertain conductor positions and a method of moments package is then used to finalize the design. An open head/neck coil was designed to operate in a clinical 2T MRI system and the presented results prove the efficacy of this design methodology.

A prospective, randomized, pragmatic, health outcomes trial evaluating the incorporation of hylan G-F 20 into the treatment paradigm for patients with knee osteoarthritis (Part 1 of 2): clinical results

Objective: First, to assess the clinical effectiveness of hylan G-F 20 in an appropriate care treatment regimen (as defined by the American College of Rheumatology (ACR) 1995 guidelines) as measured by validated disease-specific outcomes and health-related quality of life endpoints for patients with osteoarthritis (OA) of the knee. Second, to utilize the measures of effectiveness and costs in an economic evaluation (see accompanying manuscript). Design: A total of 255 patients with OA of the knee were enrolled by rheumatologists or orthopedic surgeons into a prospective, randomized, open-label, 1-year, multi-centred trial, conducted in Canada. Patients were randomized to 'Appropriate care with hylan G-F 20' (AC+H) or 'Appropriate care without hylan G-F 20' (AC). Data were collected at clinic visits (baseline, 12 months) and by telephone (1, 2, 4, 6, 8, 10, and 12 months). Results: The AC+H group was superior to the AC group for all primary (% reduction in mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scale: 38% vs 13%, P=0.0001) and secondary effectiveness outcome measures. These differences were all statistically significant and exceeded the 20% difference between groups seta priori by the investigators as the minimum clinically important difference. Health-related quality of life improvements in the AC+H group were statistically superior for the WOMAC pain, stiffness and physical function (all P

Effect of a control burn on lizards and their structural environment in a eucalypt open-forest

The composition of an open-forest lizard assemblage in eastern Australia was examined before and after a low-intensity controlled fire and concurrently compared with that in an adjoining unburnt area. The effect of fire on the available structural environment and the habitat used by two focal species, Carlia vivax and Lygisaurus foliorum, was also examined. Lizard species richness was unaffected by the controlled burn as was the abundance of most species. C. vivax was the only species to display a significant reduction in abundance after fire. While the low-intensity fire resulted in significant changes to the available structural environment, there were no compensatory shifts in the habitat preferences of either C. vivax or L. foliorum. The reduction in abundance of C. vivax was congruent with this species' avoidance of burnt areas. C. vivax displayed a non-random preference for ground cover and litter cover, which were reduced in burnt areas. Changes in the availability of preferred structural habitat features are likely to contribute to changes in the abundance of some lizard species. Therefore, even low-intensity disturbances can have an impact on lizard assemblages if critical habitat features are lost or become limiting.

Iatrogenic bile duct injury: The scourge of laparoscopic cholecystectomy

Background: Laparoscopic cholecystectomy (LC) has become the first-line surgical treatment of calculous gall-bladder disease and the benefits over open cholecystectomy are well known. In the early years of LC, the higher rate of bile duct injuries compared with open cholecystectomy was believed to be due to the 'learning curve' and would dissipate with increased experience. The purpose of the present paper was to review a tertiary referral unit's experience of bile duct injuries induced by LC. Methods: A retrospective analysis was performed on all patients referred for management of an iatrogenic bile duct injury from 1981 to 2000. For injuries sustained at LC, details of time between LC and recognition of the injury, time from injury to definitive repair, type of injury, use of intraoperative cholangiography (IOC), definitive repair and postoperative outcome were recorded. The type of injury sustained at open cholecystectomy was similarly classified to allow the severity of injury to be compared. Results: There were 131 patients referred for management of an iatrogenic bile duct injury that occurred at open cholecystectomy (n = 62), liver resection (n = 5) and at LC (n = 64). Only 39% of bile duct injuries were recognized at the time of LC. Following conversion to open operation, half the subsequent procedures were considered inappropriate. When the injury was not recognized during LC, 70% of patients developed bile leak/peritonitis, almost half of whom were referred, whereas the rest underwent a variety of operative procedures by the referring surgeon. The remainder developed jaundice or abnormal liver function tests and cholangitis. An IOC was performed in 43% of cases, but failed to identify an injury in two-thirds of patients. The bile duct injuries that occurred at LC were of greater severity than with open cholecystectomy. Following definitive repair, there was one death (1.6%). Ninety-two per cent of patients had an uncomplicated recovery and there was one late stricture requiring surgical revision. Conclusions: The early prediction that the rate of injury during LC would decline substantially with increased experience has not been fulfilled. Bile duct injury that occurs at LC is of greater severity than with open cholecystectomy. Bile duct injury is recognized during LC in less than half the cases. Evidence is accruing that the use of cholangiography reduces the risk and severity of injury and, when correctly interpreted, increases the chance of recognition of bile duct injury during the procedure. Prevention is the key but, should an injury occur, referral to a specialist in biliary reconstructive surgery is indicated.

Recoverable reserves and support effects when optimizing open pit mine designs

Orebody modelling, support effects and the estimation of recoverable reserves are key parts of open pit optimization studies. A case study is presented on the estimation of recoverable reserves using an implementation of indicator kriging where metal quantity is used to select cutoffs, and support corrections founded on a conditional simulation approach. Mining selectivity is explored in the subsequent optimization study to compare results from indicator kriging of grade estimates on a regular size blocks and indicator kriging estimates on small size blocks. The use of indicator kriging models adjusted for a given selectivity and the use of grade proportions in each block for the optimization study, provide a presentation of the expected ore recovery for a predefined level of selectivity. The case study shows that indicator kriging estimation with full accounting of block grade distributions generates substantially better results in the pit optimization study. In addition, the adverse effects of small blocks and over-smoothing on optimization results are illustrated.

Engineering closure of an open pit gold operation in a semi-arid climate

Along with material characteristics and geometry, the climate in which a mine is located can have a dramatic effect on the appropriate options for rehabilitation. The paper outlines the setting, mining, milling and waste disposal at Kidston Gold Mine's open pit operations in the semi-arid climate of North Queensland, Australia, before focusing on the engineering aspects of the rehabilitation of Kidston. The mine took a holistic and proactive approach to rehabilitation, and was prepared to demonstrate a number of innovative approaches, which are described in the paper. Engineering issues that had to be addressed included the geotechnical stability and deformation of waste rock dumps, including a 240 m high in-pit dump: the construction and performance monitoring of a “store and release” cover over potentially acid forming mineralised waste rock; erosion from the side slopes of the waste rock dumps; the in-pit co-disposal of waste rock and thickened tailings; the geotechnical stability of the tailings dam wall; the potential for erosion of bare tailings; the water balance of the tailings dam; direct revegetation of the tailings; and the pit hydrology. The rehabilitation of the mine represents an important benchmark in mine site rehabilitation best practice, from which lessons applicable worldwide can be shared.

Distributional profiles of homologous open reading frames among bacterial phyla: implications for vertical and lateral transmission

If open reading frames (ORFs) have been transmitted primarily by vertical descent, the distributional profile of orthologues of each ORF should be congruent with the organismal tree or a subtree thereof. Distributional patterns not reconciled parsimoniously with tree-like descent and loss are prima facie evidence of lateral gene transfer. Herein, a rigorous criterion for recognizing ORF distributions is described and implemented; it does not require the inference of phylogenetic trees, nor does it assume any specific tree. Because lineage-specific differences in rates of sequence change can also generate unexpected distributional patterns, rate artefacts, were controlled for by requiring pairwise matches between ORFs to exceed a rigorous inclusion threshold, but absence of a match was assessed against a more-permissive exclusion threshold. Applying this dual-threshold criterion to cross-domain and cross-phylum distributional patterns for ORFs in 23 bacterial genomes, a relative abundance of ORFs was observed that find a match in exactly seven other bacterial phyla; 94-99% of these ORFs also find matches among the Archaea and/or Eukarya. In the larger (and some smaller) bacterial genomes, ORFs that find matches in exactly one other bacterial phylum are also relatively abundant, but fewer of these have non-bacterial homologues; most of their matches within the Bacteria are to the Proteobacteria and/or Firmicutes, which cannot be sister lineages to all bacteria. ORFs that are neither distributed universally among the Bacteria, nor necessarily shared with topologically adjacent lineages, are preferentially enriched in large bacterial genomes.

Surgical programme at Royal Alexandra Hospital, Sydney, for Papua New Guinea children with congenital heart disease, 1978-1994

Objective : To report the history of the Royal Alexandra Hospital for Children (RAHC) Papua New Guinea (PNG) cardiac surgical programme and describe the selection, preoperative clinical features and postoperative outcome of children with congenital heart disease managed by the programme. Methods : Details for each of the PNG cardiac patients admitted to RAHC following selection by visiting cardiologists between 1978 and 1994 were entered into a database, and analysed and interpreted. Results : A congenital heart defect was confirmed in 165 of the 170 children selected. The male to female ratio was 1:1 and the mean age on admission to RAHC was 5.5 years. Almost all of the children for whom data were available (98%) had a weight for age and 41% had a height for age less than the 3rd centile. One-sixth had delayed milestones. A large number were tachypnoeic, in heart failure, or had pulmonary hypertension on admission. Ventricular septal defect and tetralogy of Fallot were the commonest defects, and lesions such as aortic stenosis, coarctation of the aorta and transposition of the great arteries were absent or rare. Thirty-one (19%) of the children selected initially did not receive surgery because of pulmonary hypertension, or because the lesions did not fall within the programme guidelines for operation. One hundred and twenty-nine children had corrective and four had palliative procedures. Half of the operated children had postoperative complications. Eight children died, all following open-heart procedures, giving a case fatality rate of 6%. Preoperative tachypnoea, hepatomegaly, cardiac failure and pulmonary hypertension were strongly associated with poor outcome. Conclusions : The programme was an arduous exercise for all organizations concerned, but achieved comparatively good short-term outcomes. The experience gained should assist in planning for similar programmes.

Quadriceps activation in closed and in open kinetic chain exercise

Purpose: For treatment of various knee disorders, muscles are trained in open or closed kinetic chain tasks. Coordination between the heads of the quadriceps muscle is important for stability and optimal joint loading for both the tibiofemoral and the patellofemoral joint. The aim of this study was to examine whether the quadriceps femoris muscles are activated differently in open versus closed kinetic chain tasks. Methods: Ten healthy men and women (mean age 28.5 +/- 0.7) extended the knees isometrically in open and closed kinetic chain tasks in a reaction time paradigm using moderate force. Surface electromyography (EMG) recordings were made from four different parts of the quadriceps muscle. The onset and amplitude of EMG and force data were measured. Results: In closed chain knee extension, the onset of EMG activity of the four different muscle portions of the quadriceps was more simultaneous than in the open chain. In open chain, rectus femoris (RF) had the earliest EMG onset while vastus medialis obliquus was activated last (7 +/- 13 ms after RF EMG onset) and with smaller amplitude (40 +/- 30% of maximal voluntary contraction (MVC)) than in closed chain (46 +/- 43% MVC). Conclusions: Exercise in closed kinetic chain promotes more balanced initial quadriceps activation than does exercise in open kinetic chain. This may be of importance in designing training programs aimed toward control of the patellofemoral joint.

Asymmetric contribution of α and β subunits to the activation of αβ heteromeric glycine receptors

This study investigated the role of beta subunits in the activation of alphabeta heteromeric glycine receptor (GlyR) chloride channels recombinantly expressed in HEK293 cells. The approach involved incorporating mutations into corresponding positions in alpha and beta subunits and comparing their effects on receptor function. Although cysteine-substitution mutations to residues in the N-terminal half of the alpha subunit M2-M3 loop dramatically impaired the gating efficacy, the same mutations exerted little effect when incorporated into corresponding positions of the beta subunit. Furthermore, although the alpha subunit M2-M3 loop cysteines were modified by a cysteine-specific reagent, the corresponding beta subunit cysteines showed no evidence of reactivity. These observations suggest structural or functional differences between alpha and beta subunit M2-M3 loops. In addition, a threonine-->leucine mutation at the 9' position in the beta subunit M2 pore-lining domain dramatically increased the glycine sensitivity. By analogy with the effects of the same mutation in other ligand-gated ion channels, it was concluded that the mutation affected the GlyR activation mechanism. This supports the idea that the GlyR beta subunit is involved in receptor gating. In conclusion, this study demonstrates that beta subunits contribute to the activation of the GlyR, but that their involvement in this process is significantly different to that of the alpha subunit.