Perchlorate and radioiodide kinetics across life stages in the human: using PBPK models to predict dosimetry and thyroid inhibition and sensitive subpopulations based on developmental stage

Perchlorate (ClO4(-)) is a drinking-water contaminant, known to disrupt thyroid hormone homeostasis in rats. This effect has only been seen in humans at high doses, yet the potential for long term effects from developmental endocrine disruption emphasizes the need for improved understanding of perchlorate's effect during the perinatal period. Physiologically based pharmacokinetic/dynamic (PBPK/PD) models for ClO4(-) and its effect on thyroid iodide uptake were constructed for human gestation and lactation data. Chemical specific parameters were estimated from life-stage and species-specific relationships established in previously published models for various life-stages in the rat and nonpregnant adult human. With the appropriate physiological descriptions, these kinetic models successfully simulate radioiodide data culled from the literature for gestation and lactation, as well as ClO4(-) data from populations exposed to contaminated drinking water. These models provide a framework for extrapolating from chemical exposure in laboratory animals to human response, and support a more quantitative understanding of life-stage-specific susceptibility to ClO4(-). The pregnant and lactating woman, fetus, and nursing infant were predicted to have higher blood ClO4(-) concentrations and greater thyroid iodide uptake inhibition at a given drinking-water concentration than either the nonpregnant adult or the older child. The fetus is predicted to receive the greatest dose (per kilogram body weight) due to several factors, including placental sodium-iodide symporter (NIS) activity and reduced maternal urinary clearance of ClO4(-). The predicted extent of iodide inhibition in the most sensitive population (fetus) is not significant (approximately 1%) at the U.S. Environmental Protection Agency reference dose (0.0007 mg/kg-d).

Pneumothorax in cystic fibrosis: a retrospective case series

Pneumothorax is a known complication in cystic fibrosis (CF), associated with poor outcome. Records of CF patients with pneumothorax at the Royal Children's Hospital, Melbourne between 1990 and 2004 were reviewed, and the characteristics, sputum culture results, lung function, treatment, and outcome for the 11 patients who had pneumothoraces were described.

Does splenectomy in cystic fibrosis related liver disease improve lung function and nutritional status? A case series

AIMS

To review the effect of total splenectomy on lung function and nutrition in children with cystic fibrosis related liver disease (CFLD) and associated portal hypertension. The stated indications for surgery and the short and long term risks of the procedure were also documented.

METHOD

Over a 25 year period from January 1980 to June 2005, approximately 650 patients with cystic fibrosis (CF) were treated at the Royal Children's Hospital, Melbourne, Australia. Nine patients with CFLD who underwent a splenectomy during that time were identified and their medical records were reviewed.

RESULTS

FEV1% predicted dropped by -16+/-11% in the two years pre-splenectomy. This contrasts with the increase in FEV1% predicted of 2+/-16% in the two years post-splenectomy (p = 0.05). The cumulative gain in WAZ score (DeltaWAZ pre) over the two years prior to splenectomy of 0.045+/-0.69 was not significantly different from the cumulative gain in WAZ score (DeltaWAZ post) for the two years after splenectomy of 0.15+/-0.36 (p = 0.65). The average age at splenectomy was 14.8 years (SD = 3 years). The average weight of an excised spleen was 983 g (SD = 414 g). There were no deaths associated with splenectomy. The median length of follow up post-splenectomy was 6.0 years (range 0.7-15.8). There were no episodes of bacterial peritonitis or overwhelming sepsis.

CONCLUSIONS

Splenectomy may have a beneficial effect on lung function although this may not manifest itself until the second year post-splenectomy. Splenectomy in patients with CFLD appears to be a safe procedure.

Analysis of algorithms predicting blood:air and tissue:blood partition coefficients from solvent partition coefficients for prevalent components of JP-8 jet fuel

Algorithms predicting tissue and blood partition coefficients (PCs) from solvent properties were compared to assess their usefulness in a petroleum mixture physiologically based pharmacokinetic/pharmacodynamic model. Measured blood:air and tissue:blood PCs for rat and human tissues were sought from literature resources for 14 prevalent jet fuel (JP-8) components. Average experimental PCs were compared with predicted PCs calculated using algorithms from 9 published sources. Algorithms chosen used solvent PCs (octanol:water, saline or water:air, oil:air coefficients) due to the relative accessibility of these parameters. Tissue:blood PCs were calculated from ratios of predicted tissue:air and experimental blood:air values (PCEB). Of the 231 calculated values, 27% performed within +/- 20% of the experimental PC values. Physiologically based equations (based on water and lipid components of a tissue type) did not perform as well as empirical equations (derived from linear regression of experimental PC data) and hybrid equations (physiological parameters and empirical factors combined) for the jet fuel components. The major limitation encountered in this analysis was the lack of experimental data for the selected JP-8 constituents. PCEB values were compared with tissue:blood PCs calculated from ratios of predicted tissue:air and predicted blood:air values (PCPB). Overall, 68% of PCEB values had smaller absolute % errors than PCPB values. If calculated PC values must be used in models, a comparison of experimental and predicted PCs for chemically similar compounds would estimate the expected error level in calculated values.

A multivariate analysis of the factors predicting hearing outcome after surgery for cholesteatoma in children

OBJECTIVE

To explore factors influencing hearing outcomes in children treated by canal wall up (CWU) and canal wall down (CWD) mastoid surgery.

METHODS

Retrospective cohort study including three units in Bristol and Bath, UK. Ninety consecutive children underwent cholesteatoma mastoid surgery, with the first procedure between 1998 and 2001; minimum follow up was three disease-free years.

RESULTS

The CWU and CWD cohorts significantly differed in pre-operative stage and hearing. After disease eradication, air conduction (AC) thresholds changed by +4.0 dB (95 per cent confidence intervals (95% CI) -2.0, 10.1) in the CWD group and -5.3 dB (95% CI -9.3, 1.3) in the CWU group (p=0.029). Using multiple linear regression to account for cohort differences, AC thresholds were increased by: pre-operative AC threshold (p<0.0001), initial ossicular stage (p=0.013), and CWD-surgery (p=0.005).

CONCLUSION

Disease-free hearing was better with CWU-surgery, less initial ossicular damage, and better pre-operative hearing. Worse initial disease increased the likelihood of CWD surgery. Wider use of ossiculoplasty in the CWU cohort (51 per cent vs 5 per cent) may partially explain the superior results.

Increased levels of SNAP-25 and synaptophysin in the dorsolateral prefrontal cortex in bipolar I disorder

OBJECTIVE

In order to identify whether the mechanisms associated with neurotransmitter release are involved in the pathologies of bipolar disorder and schizophrenia, levels of presynaptic [synaptosomal-associated protein-25 (SNAP-25), syntaxin, synaptophysin, vesicle-associated membrane protein, dynamin I] and structural (neuronal cell adhesion molecule and alpha-synuclein) neuronal markers were measured in Brodmann's area 9 obtained postmortem from eight subjects with bipolar I disorder (BPDI), 20 with schizophrenia and 20 controls.

METHODS

Determinations of protein levels were carried out using Western blot techniques with specific antibodies. Levels of mRNA were measured using real-time polymerase chain reaction.

RESULTS

In BPDI, levels of SNAP-25 (p < 0.01) and synaptophysin (p < 0.05) increased. There were no changes in schizophrenia or any other changes in BPDI. Levels of mRNA for SNAP-25 were decreased in BPDI (p < 0.05).

CONCLUSION

Changes in SNAP-25 and synaptophysin in BPDI suggest that changes in specific neuronal functions could be linked to the pathology of the disorder.

Clinical assessment alone will not benefit patients with coronary heart disease: failure to achieve cholesterol targets in 12,045 patients--the Healthwise II study

Healthwise II, a nurse-led audit programme in primary care during 1999-2002, assessed the uptake of secondary preventative measures for coronary heart disease (CHD). Risk factors, cardiovascular medications and blood cholesterol were recorded; 'at risk' patients were invited for a review after 6 months. Of 17,570 patients assessed, CHD was clinically present in 12,045 (69%); in these, aspirin usage was high (78%) but fewer patients were on a beta-blocker (40%), angiotensin-converting enzyme inhibitor (27%) or statin (49%). Blood pressure (BP) was controlled (<140/90) in only 41% of patients. Total cholesterol was >5 mmol/l in 49% of all CHD patients, half of whom were taking a statin. In the statin users, total cholesterol was uncontrolled (>5 mmol/l) in 38%. At follow-up, BP control remained at 42%, statin use increased to 57% and cholesterol remained elevated in 46%. Simple assessment in an audit programme fails to trigger change, and risk-factor modification for CHD remains inadequate.

The use of perioperative SofradexR eardrops in preventing tympanostomy tube blockage: a prospective double-blinded randomized-controlled trial

Around 11-12% of tympanostomy tubes are reported to become blocked by middle ear secretions or blood immediately following surgery, and so no longer function. Many otologists routinely instil an antibiotic and steroid-containing solution at the time of surgery in the belief that this may reduce this complication. The aim of the study was to investigate the efficacy of instilling the antibiotic and steroid-containing solution Sofradex at the time of grommet insertion in preventing grommet blockage. Double-blind randomized-controlled trial, comparing rates of grommet blockage in ears treated with Sofradex drops against control (no drops) in patients undergoing bilateral grommet insertion. Sixty-one pairs of results were obtained. There was a significant difference between the rates of grommet blockage in the two groups. Grommets with Sofradex drops instilled perioperatively were nine times less likely to be blocked than controls [1.6%versus 13.1%, odds ratio (Sofradex/control) = 9.06, 95% confidence interval (CI): 1.04-78.82, P = 0.05]. There was no association between grommet blockage and perioperative bleeding or the nature and presence of middle ear secretions. Sofradex eardrops are effective in reducing the rate of grommet blockage when instilled perioperatively.

PBPK model for radioactive iodide and perchlorate kinetics and perchlorate-induced inhibition of iodide uptake in humans

Detection of perchlorate (ClO4-) in several drinking water sources across the U.S. has lead to public concern over health effects from chronic low-level exposures. Perchlorate inhibits thyroid iodide (I-) uptake at the sodium (Na+)-iodide (I-) symporter (NIS), thereby disrupting the initial stage of thyroid hormone synthesis. A physiologically based pharmacokinetic (PBPK) model was developed to describe the kinetics and distribution of both radioactive I- and cold ClO4- in healthy adult humans and simulates the subsequent inhibition of thyroid uptake of radioactive I- by ClO4-. The model successfully predicts the measured levels of serum and urinary ClO4- from drinking water exposures, ranging from 0.007 to 12 mg ClO4-/kg/day, as well as the subsequent inhibition of thyroid 131I- uptake. Thyroid iodine, as well as total, free, and protein-bound radioactive I- in serum from various tracer studies, are also successfully simulated. This model's parameters, in conjunction with corresponding model parameters established for the male, gestational, and lactating rat, can be used to estimate parameters in a pregnant or lactating human, that have not been or cannot be easily measured to extrapolate dose metrics and correlate observed effects in perchlorate toxicity studies to other human life stages. For example, by applying the adult male rat:adult human ratios of model parameters to those parameters established for the gestational and lactating rat, we can derive a reasonable estimate of corresponding parameters for a gestating or lactating human female. Although thyroid hormones and their regulatory feedback are not incorporated in the model structure, the model's successful prediction of free and bound radioactive I- and perchlorate's interaction with free radioactive I- provide a basis for extending the structure to address the complex hypothalamic-pituitary-thyroid feedback system. In this paper, bound radioactive I- refers to I- incorporated into thyroid hormones or iodinated proteins, which may or may not be bound to plasma proteins.

Evidence for competitive inhibition of iodide uptake by perchlorate and translocation of perchlorate into the thyroid

Various published data sets that investigate the potential effect of exogenous perchlorate (ClO4-) on the uptake of iodide in the thyroid and subsequent changes in thyroid hormone levels are available. In order to best use the data towards the prediction of human health effects resulting from ClO4- exposure, the available literature data must be integrated into a self-consistent, coherent, and parsimonious quantitative model based on the most likely mode of action of perchlorate effect on thyroid function. We submit that the simplest mode of action for ClO4- in the thyroid that remains consistent with all available data involves competitive inhibition of iodide transport into the thyroid follicle, transport of perchlorate into the thyroid follicle against a concentration gradient, further transport into the thyroid lumen (where it may again interfere with iodide transport), and, finally, passive diffusion back into the blood. We believe this description of perchlorate's kinetic behavior should serve as the foundation for predictive physiologically based pharmacokinetic (PBPK) models and as a working hypothesis for further experimental exploration.

Cervical lymphadenopathy due to mycobacterial infection: a diagnostic protocol

Mycobacterial cervical lymphadenopathy is relatively uncommon in the United Kingdom; when cases do occur opportunities for early diagnosis and treatment may be missed. We have reviewed twenty-three cases of mycobacterial cervical lymphadenopathy presenting to an urban general hospital over a four-year period. We discuss the techniques available to aid a diagnosis of mycobacterial disease and suggest a protocol to allow efficient use of these techniques.

Canine trachealis muscle shortening and cartilage mechanics

Canine trachealis muscle will shorten by 70% of resting length when maximally stimulated in vitro. In contrast, trachealis muscle will shorten by only 30–40% when stimulated in vivo. To examine the possibility that an elastic load applied by the tracheal cartilage contributes to the in vivo limitation of shortening, single pairs of sonomicrometry crystals were inserted into the trachealis muscle at the level of the fifth cartilage ring in five dogs. The segment containing the crystals was then excised and mounted on a tension-testing apparatus. Points on the active length-tension curve and the passive length-tension relation of the cartilage only were determined. The preload applied to the muscle before contraction varied from 10 to 40 g (mean 21 ± 4 g). The afterload applied by the cartilage during trachealis contraction ranged from 13 to 56 g (30 ± 6 g). The calculated elastic afterloads were substantial and appeared to be sufficient to explain the degree of shortening observed in four of the seven rings; in the remaining three rings, the limitation of shortening was greater than would be expected from the elastic load provided by the cartilage. Additional sources of loading and/or additional mechanisms may contribute to limited in situ shortening. In summary, tracheal cartilage applies a preload and an elastic afterload to the trachealis that are substantial and contribute to the limitation of trachealis muscle shortening in vivo.

Small "indeterminate" lesions on CT of the liver: a follow-up study of stability

Distinguishing between small benign malformations in the liver and early metastatic disease remains difficult. We identified a group of 115 patients with known or suspected malignant disease who had "indeterminate" small liver lesions and who underwent 2-16 CT examinations (median 5) over a follow up period of 6-60 months (median 16). The size, shape, edge, homogeneity and attenuation of each of these lesions was assessed. The lesions were classified by their behaviour on follow up CT as either stable (79%) or unstable (21%). The unstable lesions (n=62) included 37 that grew larger and 25 that became smaller or disappeared in patients undergoing anti-tumour therapy. Image features predictive of stable behaviour were small size and sharp edge. Heterogeneity and soft tissue attenuation were significantly associated with unstable behaviour, but these features were seen in only a small minority of cases. Shape had no predictive value. A logistic regression model was constructed based on size and edge to allow an estimate to be made of the likelihood of an individual lesion being unstable. In patients with known or suspected malignant disease, the majority of isolated small liver lesions found on CT are benign. Although size under 5 mm and a sharp margin are favourable features, this appearance does not exclude malignancy.

Laryngeal foreign bodies in children: first stop before the right main bronchus

Laryngeal foreign bodies may produce either complete or incomplete airways obstruction. In complete airways obstruction the presentation is with calamitous respiratory difficulty. However incomplete laryngeal obstruction may present with less severe symptoms, resulting in possible misdiagnosis and confusion with other causes of upper airway obstruction such as infectious croup. This report describes three cases of incomplete laryngeal obstruction secondary to inhaled foreign bodies. In each case, the diagnosis of an inhaled foreign body was initially missed, resulting in delay in diagnosis and in one case prolonged recovery. The importance of considering laryngeal foreign bodies, both in cases of suspected foreign body inhalation and clinical cases of incomplete laryngeal obstruction are discussed.

PBPK predictions of perchlorate distribution and its effect on thyroid uptake of radioiodide in the male rat

Due to perchlorate's (ClO4-) ability to competitively inhibit thyroid iodide (I-) uptake through the sodium-iodide symporter (NIS), potential human health risks exist from chronic exposure via drinking water. Such risks may include hypothyroidism, goiter, and mental retardation (if exposure occurs during critical periods in neurodevelopment). To aid in predicting perchlorate's effect on normal I- kinetics, we developed a physiologically-based pharmacokinetic (PBPK) model for the adult male rat. The model structure describes simultaneous kinetics for both anions together with their interaction at the NIS, in particular, the inhibition of I- uptake by ClO4-. Subcompartments and Michaelis-Menten (M-M) kinetics were used to describe active uptake of both anions in the thyroid, stomach, and skin. Separate compartments for kidney, liver, plasma, and fat were described by passive diffusion. The model successfully predicts both 36ClO4- and 125I- kinetics after iv doses of 3.3 mg/kg and 33 mg/kg, respectively, as well as inhibition of thyroid 125I- uptake by ClO4- after iv doses of ClO4- (0.01 to 3.0 mg/kg). The model also predicts serum and thyroid ClO4- concentrations from 14-day drinking water exposures (0.01 to 30.0 mg ClO4-/kg/day) and compensation of perchlorate-induced inhibition of radioiodide uptake due to upregulation of the thyroid. The model can be used to extrapolate dose metrics and correlate observed effects in perchlorate toxicity studies to other species and life stages, such as rat gestation (Clewell et al., 2003). Because the model successfully predicts perchlorate's interaction with iodide, it provides a sound basis for future incorporation of the complex hypothalamic-pituitary-thyroid feedback system.

Predicting fetal perchlorate dose and inhibition of iodide kinetics during gestation: a physiologically-based pharmacokinetic analysis of perchlorate and iodide kinetics in the rat

Perchlorate (ClO4-) disrupts endocrine homeostasis by competitively inhibiting the transport of iodide (I-) into the thyroid. The potential for health effects from human exposure to ClO4- in drinking water is not known, but experimental animal studies are suggestive of developmental effects from ClO4- induced iodide deficiency during gestation. Normal hormone-dependent development relies, in part, on synthesis of hormones in the fetal thyroid from maternally supplied iodide. Although ClO4- crosses the placenta, the extent of inhibition in the fetal thyroid is unknown. A physiologically-based pharmacokinetic (PBPK) model was developed to simulate ClO4- exposure and the resulting effect on iodide kinetics in rat gestation. Similar to concurrent model development for the adult male rat, this model includes compartments for thyroid, stomach, skin, kidney, liver, and plasma in both mother and fetus, with additional compartments for the maternal mammary gland, fat, and placenta. Tissues with active uptake are described with multiple compartments and Michaelis-Menten (M-M) kinetics. Physiological and kinetic parameters were obtained from literature and experiment. Systemic clearance, placental-fetal transport, and M-M uptake parameters were estimated by fitting model simulations to experimental data. The PBPK model is able to reproduce maternal and fetal iodide data over five orders of magnitude (0.36 to 33,000 ng/kg 131I-), ClO4- distribution over three orders of magnitude (0.01 to 10 mg/kg-day ClO4-) and inhibition of maternal thyroid and total fetal I- uptake. The model suggests a significant fetal ClO4- dose in late gestation (up to 82% of maternal dose). A comparison of model-predicted internal dosimetrics in the adult male, pregnant, and fetal rat indicates that the fetal thyroid is more sensitive to inhibition than that of the adult.

Decreased phorbol ester binding in the parahippocampal gyrus from subjects with schizophrenia is not associated with changes in protein kinase C

Combining in situ radioligand binding with autoradiography, we previously identified a reduction of [(3)H]phorbol 12,13-dibutyrate binding in the parahippocampal gyrus from schizophrenic subjects. To determine whether these changes were due to decreases in the level of protein kinase C, we measured [(3)H]phorbol 12,13-dibutyrate binding, levels of the protein kinase C isoforms alpha, beta, delta, epsilon, gamma, eta and theta, as well as protein kinase C activity in crude particulate membranes from parahippocampal gyri of 15 schizophrenic and 15 control subjects. There was a significant decrease in the density (mean +/- SEM: 6.56 +/- 0.73 pmol mg(-1) vs 9.68 +/- 1.22 pmol mg(-1); P < 0.05) and affinity (mean K(D) +/- SEM: 4.64 +/- 0.34 nM vs 2.95 +/- 0.35 nM; P < 0.005) of [(3)H]phorbol 12,13-dibutyrate binding in homogenates from schizophrenic subjects. There were no significant changes in levels of the protein kinase C isoforms which are known to bind phorbol esters or in the activity of protein kinase C in membranes from schizophrenic subjects. These results suggest that there are changes in molecules capable of binding [(3)H]phorbol 12,13-dibutyrate, other than protein kinase C, in the parahippocampal gyrus from subjects with schizophrenia.

Assessment of dermal absorption and penetration of components of a fuel mixture (JP-8)

Occupational and environmental multi-chemical exposures are extremely common. Methods for assessment of the risks from dermal exposures to complex mixtures vary depending on the information available. The composition of a volatile mixture (such as JP-8 jet fuel) can change radically, depending on the phase of the mixture - vapor, liquid or aerosol. Assessing the absorption (into the skin) and penetration (through the skin) of components of the mixture can reduce uncertainty in the risk assessment process. Permeability coefficients of the 12 individual components that could be detected to penetrate the skin could be used to assess the toxicity of each individual component in the JP-8. The penetration of each of these components is related to and can be predicted from molecular weight and octanol water partition coefficients of that component. The composition of the components that penetrate the skin would be different from the composition of JP-8 because the permeability of the components differs by two orders of magnitude. Concentrations of the aliphatic chemicals found in the skin correlated well with carbon number. The JP-8 jet fuel is used as an example of how component data on absorption and penetration can be integrated into an assessment (McDougal et al., Toxicol Sci 2000; 55: 247-255). The component approach shows promise for estimating systemic toxicity of mixtures. Local toxicity (irritation, sensitization, etc.) may be better understood in the future when quantitative information becomes available about the duration and magnitude of chemical exposures required to cause local effects.

Pituitary autoantibodies in lymphocytic hypophysitis target both gamma- and alpha-Enolase - a link with pregnancy?

The first target autoantigen to have been identified in lymphocytic hypophysitis is a 49 kDa protein, identified as alpha-enolase. Pituitary autoimmunity is strongly associated with pregnancy and we have shown that pituitary autoantibodies from patients with peripartum lymphocytic hypophysitis also recognise enolase in the placenta. Enolase exists in different forms as a number of isoenzymes, which are homo- or heterodimers of three subunits, alpha, beta and gamma. alphaalpha-enolase is ubiquitous, betabeta-enolase is muscle-specific and gammagamma-enolase, which is restricted to neuronal tissue and neuroendocrine cells, is known as neuron-specific enolase (NSE). NSE is expressed in normal human pituitary and pituitary neoplasms. The current study investigated which isoforms of enolase in pituitary and placenta reacted with the sera of patients with lymphocytic hypophysitis. Immunoblotting of two-dimensional gels of human pituitary cytosolic proteins showed that autoantibodies in patient sera react with both an acidic form, and more neutral forms of enolase. Immunoblotting with a monoclonal antibody to NSE confirmed the identity of the acidic enolase isoform as the gammagamma-isoform in both pituitary and placental samples. Gamma-enolase, i.e. NSE, was detected by immunohistochemistry in term placenta in decidua, syncytiotrophoblasts, anchoring villi and terminal villi. Our study is the first to describe the cellular localisation of NSE in normal human placenta, thus establishing a direct link between pituitary and placental autoantigens. This link provides a theoretical basis for the strong prediliction of lymphocytic hypophysitis to occur during or after pregnancy.

Growth and adrenal suppression in asthmatic children on moderate to high doses of fluticasone propionate

OBJECTIVE

Growth and adrenal suppression have been reported in asthmatic children using high-dose inhaled fluticasone propionate (FP). Inhaled FP, given at moderate doses (250-750 microg/day), has not been documented to be associated with growth or adrenal suppression in asthmatic children until recently. We report three cases illustrating these side effects.

METHODS

Growth and adrenal suppression, after the introduction of inhaled FP, were observed in three prepubertal young asthmatic children referred to our asthma clinic and growth clinic. Growth centile and velocity were assessed by longitudinal stadiometry height measurements. Early morning plasma cortisol levels, and glucagon stimulation tests were used to assess the pituitary adrenal axis.

RESULTS

Severe growth and adrenal suppression were noted in three children while they were on moderate doses of inhaled FP. Improvements in growth and adrenal function were observed following cessation or dose reduction of inhaled FP.

CONCLUSIONS

Unexpected growth and adrenal suppression may occur in young asthmatic children using moderate doses of inhaled FP.

Telemedicine for the delivery of professional development for health, education and welfare professionals in two remote mining towns

Over a two-year period, telemedicine was used to deliver training and development services for health, education and welfare staff in two remote towns in South Australia - Roxby Downs and Coober Pedy. Both are mining towns but they have different profiles in terms of the community's mental health needs. The services were provided by the Child and Adolescent Mental Health Services (CAMHS) from the Women's and Children's Hospital in Adelaide, South Australia. The media used were videoconferencing, telephone, video-tapes, the Internet and printed material. During 1998-9, professional staff in the two locations participated in structured videoconferencing seminars that addressed important mental health topics, chosen in response to surveys of the needs of the participants. The videoconferencing sessions were sometimes used to discuss specific patient cases. Each remote town was also supported via videoconferencing by a nominated office of the CAMHS: Roxby Downs by the suburban office at Port Adelaide and Coober Pedy by the office in the industrial town of Port Pirie. This customized support was an important factor in the success of the professional development network.

3.1 Scholarship and the university

Universities now exist in an environment of increasing accountability for their academic performance, both in teaching and research. Dental schools are expected to meet the academic expectations of their parent university and, in addition, to contribute to the health-care needs of the community. Individual staff members must achieve collectively the performance targets required of their school and individually must develop skills and expertise in their academic and clinical activities to merit tenure and promotion. This discussion examines the issues which impact on current problems of recruitment and retention of academic staff in dental schools internationally. The essential issue is career development in a manner which maintains the values that will ensure the credibility of dentistry as a scientifically based discipline and profession, while balancing the achievable academic needs with the added demands of achieving specialist clinical skills. Central to this balance is recognition that scholarship, which provides the bridge between research and teaching, can be broadly defined and that different individuals can be scholarly in a range of ways. Increasingly, schools are recognizing the importance of providing structured opportunities and guidance for career development of younger staff and of the need for flexibility in their criteria for tenure and promotion, recognizing that a diversity of individual strengths and teamworking are necessary both for the collective performance of the institution and the morale and development of the individual.