Where next for youth mental health services in Ireland?

To date, Ireland has been a leading light in the provision of youth mental health services. However, cognisant of the efforts of governmental and non-governmental agencies working in youth mental health, there is much to be done. Barriers into care as well as discontinuity of care across the spectrum of services remain key challenges. This editorial provides guidance for the next stage of development in youth mental care and support that will require significant national engagement and resource investment.

Distinguishing Petroleum (Crude Oil and Fuel) From Smoke Exposure within Populations Based on the Relative Blood Levels of Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX), Styrene and 2,5-Dimethylfuran by Pattern Recognition Using Artificial Neural Networks.

Studies of exposure to petroleum (crude oil/fuel) often involve monitoring benzene, toluene, ethylbenzene, xylenes (BTEX), and styrene (BTEXS) because of their toxicity and gas-phase prevalence, where exposure is typically by inhalation. However, BTEXS levels in the general U.S. population are primarily from exposure to tobacco smoke, where smokers have blood levels on average up to eight times higher than nonsmokers. This work describes a method using partition theory and artificial neural network (ANN) pattern recognition to classify exposure source based on relative BTEXS and 2,5-dimethylfuran blood levels. A method using surrogate signatures to train the ANN was validated by comparing blood levels among cigarette smokers from the National Health and Nutrition Examination Survey (NHANES) with BTEXS and 2,5-dimethylfuran signatures derived from the smoke of machine-smoked cigarettes. Classification agreement for an ANN model trained with relative VOC levels was up to 99.8% for nonsmokers and 100.0% for smokers. As such, because there is limited blood level data on individuals exposed to crude oil/fuel, only surrogate signatures derived from crude oil and fuel were used for training the ANN. For the 2007-2008 NHANES data, the ANN model assigned 7 out of 1998 specimens (0.35%) and for the 2013-2014 NHANES data 12 out of 2906 specimens (0.41%) to the crude oil/fuel signature category.

Comparison of veterinary drugs and veterinary homeopathy: part 2.

Part 2 of this narrative review outlines the theoretical and practical bases for assessing the efficacy and effectiveness of conventional medicines and homeopathic products. Known and postulated mechanisms of action are critically reviewed. The evidence for clinical efficacy of products in both categories, in the form of practitioner experience, meta-analysis and systematic reviews of clinical trial results, is discussed. The review also addresses problems and pitfalls in assessing data, and the ethical and negative aspects of pharmacology and homeopathy in veterinary medicine.

Comparison of veterinary drugs and veterinary homeopathy: part 1.

For many years after its invention around 1796, homeopathy was widely used in people and later in animals. Over the intervening period (1796-2016) pharmacology emerged as a science from Materia Medica (medicinal materials) to become the mainstay of veterinary therapeutics. There remains today a much smaller, but significant, use of homeopathy by veterinary surgeons. Homeopathic products are sometimes administered when conventional drug therapies have not succeeded, but are also used as alternatives to scientifically based therapies and licensed products. The principles underlying the veterinary use of drug-based and homeopathic products are polar opposites; this provides the basis for comparison between them. This two-part review compares and contrasts the two treatment forms in respect of history, constituents, methods of preparation, known or postulated mechanisms underlying responses, the legal basis for use and scientific credibility in the 21st century. Part 1 begins with a consideration of why therapeutic products actually work or appear to do so.

Cross-cultural perception of six commercial olive oils: A study with Spanish and US consumers.

A cross-cultural study was conducted with Spanish and US consumers to gain an insight into the preferred characteristics of olive oils in both countries. Six commercial olive oils (four samples from Spain and two samples from the US) were analyzed by a highly trained panel (descriptive analysis) and also by two consumers' groups (100 consumers from Spain and 100 from the US). Demographic, acceptability, and Just-About-Right data were collected to study the preferences of both groups, and the relationships with descriptive data were explored to determine the drivers of like/dislike. The Spanish extra virgin olive oils and the imported US extra virgin olive oil were characterized by having bitter, pungent, and more green notes, and were preferred by the Spanish consumers. The US consumers liked the bland Spanish refined olive oil, and the Californian olive oil that was characterized by fruity, floral, and sweet notes. The results showed that the Spanish consumers were more aware about olive oil quality in general than their US counterparts, maybe because of a higher usage of the product in Spain. The present study provides essential data which might help producers in designing and promoting olive oils matching US consumers' requirements, an emerging market for this Mediterranean product.

Sugammadex for the reversal of muscle relaxation in general anaesthesia: a systematic review and economic assessment.

BACKGROUND: Sugammadex (Bridion) is a newly developed agent for the reversal of neuromuscular blockade (NMB) induced by rocuronium or vecuronium. Sugammadex can reverse profound blockade and can be given for immediate reversal and its use would avoid the potentially serious adverse effects of the currently used agent, succinylcholine. Also, sugammadex can reverse NMB more quickly and predictably than existing agents. OBJECTIVES: To determine the clinical effectiveness and cost-effectiveness of sugammadex for the reversal of muscle relaxation after general anaesthesia in UK practice following routine or rapid induction of NMB. DATA SOURCES: Medical databases [including MEDLINE, EMBASE, CINAHL, Science Citation Index, BIOSIS and Cochrane Central Register of Controlled Trials (CENTRAL), conference proceedings, internet sites and clinical trials registers] were searched to identify published and unpublished studies. The main searches were carried out in May 2008 and supplemented by current awareness updates up until November 2008. REVIEW METHODS: For the clinical effectiveness review, randomised controlled trials of sugammadex against placebo or an active comparator (neostigmine + glycopyrrolate) for the reversal of moderate or profound NMB and for immediate reversal (spontaneous recovery from succinylcholine-induced blockade) were included. The primary effectiveness outcome was speed of recovery from NMB, as measured by objective monitoring of neuromuscular function. For the cost-effectiveness review, a de novo economic assessment considered the routine induction of NMB and the rapid induction and/or reversal of NMB, and threshold analyses were carried out on a series of pairwise comparisons to establish how effective sugammadex needs to be to justify its cost. RESULTS: The review of clinical effectiveness included four randomised active-control trials of sugammadex, nine randomised placebo-controlled trials and five studies in special populations. A total of 2132 titles and abstracts and 265 full-text publications were screened. The included trials indicated that sugammadex produces more rapid recovery from moderate or profound NMB than placebo or neostigmine. Median time to recovery from moderate blockade was 1.3-1.7 minutes for rocuronium + sugammadex, 21-86 minutes for rocuronium + placebo and 17.6 minutes for rocuronium + neostigmine. In profound blockade, median time to recovery was 2.7 minutes for rocuronium + sugammadex, 30 to > 90 minutes for rocuronium + placebo, and 49 minutes for rocuronium + neostigmine. Results for vecuronium were similar. In addition, recovery from NMB was faster with rocuronium reversed by sugammadex 16 mg/kg after 3 minutes (immediate reversal) than with succinylcholine followed by spontaneous recovery (median time to primary outcome 4.2 versus 7.1 minutes). The evidence base for modelling cost-effectiveness is very limited. However, assuming that the reductions in recovery times seen in the trials can be achieved in routine practice and can be used productively, sugammadex [2 mg/kg (4 mg/kg)] is potentially cost-effective at its current list price for the routine reversal of rocuronium-induced moderate (profound) blockade, if each minute of recovery time saved can be valued at approximately 2.40 pounds (1.75 pounds) or more. This is more likely to be achieved if any reductions in recovery time are in the operating room (estimated value of 4.44 pounds per minute saved) rather than the recovery room (estimated value of 0.33 pounds per minute saved). The results were broadly similar for rocuronium- and vecuronium-induced blockade. For rapid reversal of NMB it appeared that any reduction in morbidity from adopting sugammadex is unlikely to result in significant cost savings. LIMITATIONS: The evidence base was not large and many of the published trials were dose-finding and safety studies with very small sample sizes. Also, some relevant outcomes, in particular patient experience/quality of life and resources/costs used, were either not investigated or not reported. In addition, it is likely that the patients included in the efficacy trials were relatively young and in good general health compared with the overall surgical population. Regarding the economic evaluation, there appears to be no evidence linking measures of clinical efficacy to patients' health-related quality of life and mortality risks. CONCLUSIONS: Sugammadex may be a cost-effective option compared with neostigmine + glycopyrrolate for reversal of moderate NMB and also provides the facility to recover patients from profound blockade. Rocuronium + sugammadex could be considered as a replacement for succinylcholine for rapid induction (and reversal) of NMB, although this may not be a cost-effective option in some types of patient at current list prices for sugammadex. Considerable uncertainties remain about whether the full benefits of sugammadex can be realised in clinical practice.

Curative catheter ablation in atrial fibrillation and typical atrial flutter: systematic review and economic evaluation.

OBJECTIVES: To determine the safety, clinical effectiveness and cost-effectiveness of radio frequency catheter ablation (RCFA) for the curative treatment of atrial fibrillation (AF) and typical atrial flutter. DATA SOURCES: For the systematic reviews of clinical studies 25 bibliographic databases and internet sources were searched in July 2006, with subsequent update searches for controlled trials conducted in April 2007. For the review of cost-effectiveness a broad range of studies was considered, including economic evaluations conducted alongside trials, modelling studies and analyses of administrative databases. REVIEW METHODS: Systematic reviews of clinical studies and economic evaluations of catheter ablation for AF and typical atrial flutter were conducted. The quality of the included studies was assessed using standard methods. A decision model was developed to evaluate a strategy of RFCA compared with long-term antiarrhythmic drug (AAD) treatment alone in adults with paroxysmal AF. This was used to estimate the cost-effectiveness of RFCA in terms of cost per quality-adjusted life-year (QALY) under a range of assumptions. Decision uncertainty associated with this analysis was presented and used to inform future research priorities using the value of information analysis. RESULTS: A total of 4858 studies were retrieved for the review of clinical effectiveness. Of these, eight controlled studies and 53 case series of AF were included. Two controlled studies and 23 case series of typical atrial flutter were included. For atrial fibrillation, freedom from arrhythmia at 12 months in case series ranged from 28% to 85.3% with a weighted mean of 76%. Three RCTs suggested that RFCA is more effective than long-term AAD therapy in patients with drug-refractory paroxysmal AF. Single RCTs also suggested superiority of RFCA over electrical cardioversion followed by long-term AAD therapy and of RFCA plus AAD therapy over AAD maintenance therapy alone in drug-refractory patients. The available RCTs provided insufficient evidence to determine the effectiveness of RFCA beyond 12 months or in patients with persistent or permanent AF. Adverse events and complications were generally rare. Mortality rates were low in both RCTs and case series. Cardiac tamponade and pulmonary vein stenosis were the most frequently recorded complications. For atrial flutter, freedom from arrhythmia at 12 months in case series ranged from 85% to 92% with a weighted mean of 88%. Neither of the atrial flutter RCTs reported freedom from arrhythmia at 12 months. One RCT found a statistically significant benefit favouring ablation over AADs in terms of freedom from arrhythmia at a mean follow-up of 22 months. A second RCT reported a more modest effect favouring ablation in terms of freedom from atrial flutter at follow-up in older patients (mean age 78 years) after their first episode of flutter. In the atrial flutter case series, mortality was rare and the most frequent complications were atrioventricular block and haematomas. Complications in the RCTs were similar, except for those events likely to have been caused by AAD therapy (e.g. thyroid dysfunction). The review of cost-effectiveness evidence found one relevant study, which from a UK NHS perspective had a number of important limitations. The base-case analysis in the decision model demonstrated that if the quality of life benefits of RFCA are maintained over the remaining lifetime of the patient then the cost-effectiveness of RFCA appears clear. These findings were robust over a wide range of alternative assumptions, being between 7763 and 7910 pounds per additional QALY with very little uncertainty. If the quality of life benefits of RFCA are assumed to be maintained for no more than 5 years, cost-effectiveness of RFCA is dependent on a number of factors. Estimates of cost-effectiveness that explored the influence of these factors ranged from 23,000 to 38,000 pounds per QALY. CONCLUSIONS: RFCA is a relatively safe and efficacious procedure for the therapeutic treatment of AF and typical atrial flutter. There is some randomised evidence to suggest that RFCA is superior to AADs in patients with drug-refractory paroxysmal AF in terms of freedom from arrhythmia at 12 months. RFCA appears to be cost-effective if the observed quality of life benefits are assumed to continue over a patient's lifetime. However, there remain uncertainties around longer-term effects of the intervention and the extent to which published effectiveness findings can be generalised to 'typical' UK practice. All catheter ablation procedures for the treatment of AF or atrial flutter undertaken in the UK should be recorded prospectively and centrally and measures to increase compliance in recording RFCA procedures may be needed. This would be of particular value in establishing the long-term benefits of RFCA and the true incidence and impact of any complications. Collection of appropriate quality of life data within any such registry would also be of value to future clinical and cost-effectiveness research in this area. Any planned multicentre RCTs comparing RFCA against best medical therapy for the treatment of AF and/or atrial flutter should be conducted among 'non-pioneering' centres using the techniques and equipment typically employed in UK practice and should measure relevant outcomes.

Effects of nitrogen dioxide exposure and ascorbic acid supplementation on exhaled nitric oxide in healthy human subjects.

BACKGROUND: Nitric oxide (NO) is detectable in the exhaled breath, is involved in airway defence and inflammation, and probably modulates bronchial smooth muscle tone. Given the sensitivity of nitrogen oxides to local redox conditions, we postulated that exposure to oxidant or antioxidant compounds could alter concentrations of NO in the exhaled breath (eNO). We assessed the effect of nitrogen dioxide (NO(2)) and ascorbic acid exposure on eNO in healthy human subjects. METHODS: Ten healthy subjects were randomised to undergo a 20 minute single blind exposure to NO(2) (1.5 parts per million) or medical air in a crossover fashion. Exhaled NO and pulmonary function were measured before and for 3 hours after exposure. In a separate double blind crossover study 20 healthy subjects received ascorbic acid 500 mg twice daily or placebo for 2 weeks with a 6 week interim washout. Serum ascorbic acid levels and eNO were measured before and after each supplementation phase. RESULTS: NO(2) induced a decrease of 0.62 (95% CI 0.32 to 0.92) ppb in the mean post-exposure eNO (p<0.01) with no change in forced expiratory volume in 1 second (FEV(1)). Oral supplementation with ascorbic acid increased the mean serum ascorbic acid concentration by 7.4 (95% CI 5.1 to 9.7) microg/ml (63%) but did not alter eNO. CONCLUSIONS: NO(2) exposure causes a decrease in eNO, an effect which may be mediated through changes in epithelial lining fluid redox state or through a direct effect on epithelial cells. In contrast, ascorbic acid does not appear to play a significant role in the metabolism of NO in the epithelial lining fluid.

Long-term myocardial preservation: effects of hyperkalemia, sodium channel, and Na/K/2Cl cotransport inhibition on extracellular potassium accumulation during hypothermic storage.

OBJECTIVES: We previously demonstrated improved myocardial preservation with polarized (tetrodotoxin-induced), compared with depolarized (hyperkalemia-induced), arrest and hypothermic storage. This study was undertaken to determine whether polarized arrest reduced ionic imbalance during ischemic storage and whether this was influenced by Na+/K +/2Cl- cotransport inhibition. METHODS: We used the isolated crystalloid perfused working rat heart preparation (1) to measure extracellular K+ accumulation (using a K+-sensitive intramyocardial electrode) during ischemic (control), depolarized (K+ 16 mmol/L), and polarized (tetrodotoxin, 22 micromol/L) arrest and hypothermic (7.5 degrees C) storage (5 hours), (2) to determine dose-dependent (0.1, 1.0, 10 and 100 micromol/L) effects of the Na +/K+/2Cl- cotransport inhibitor, furosemide, on extracellular K+ accumulation during polarized arrest and 7.5 degrees C storage, and (3) to correlate extracellular K+ accumulation to postischemic recovery of cardiac function. RESULTS: Characteristic triphasic profiles of extracellular K+ accumulation were observed in control and depolarized arrested hearts; a significantly attenuated profile with polarized arrested hearts demonstrated reduced extracellular K+ accumulation, correlating with higher postischemic function (recovery of aortic flow was 54% +/-4% [P =.01] compared with 39% +/-3% and 32% +/-3% in depolarized and control hearts, respectively). Furosemide (0.1, 1.0, 10, and 100 micromol/L) modified extracellular K+ accumulation by -18%, -38%, -0.2%, and +9%, respectively, after 30 minutes and by -4%, -27%, +31%, and +42%, respectively, after 5 hours of polarized storage. Recovery of aortic flow was 53% +/-4% (polarized arrest alone), 56% +/-8%, 70% +/-2% (P =.04 vs control), 69% +/-4% (P =.04 vs control), and 65% +/-3% ( P =. 04 vs control), respectively. CONCLUSIONS: Polarized arrest was associated with a reduced ionic imbalance (demonstrated by reduced extracellular K+ accumulation) and improved recovery of cardiac function. Further attenuation of extracellular K + accumulation (by furosemide) resulted in additional recovery.

Exogenous adenosine, supplied transiently during reperfusion, ameliorates depressed endogenous adenosine production in the post-ischemic rat heart.

Adenosine (ADO) is an important endogenous protective metabolite of the heart which also exerts beneficial effects when exogenously supplied before or after ischemia. Previous studies established that after initial massive release of ADO, its endogenous production could be significantly reduced following myocardial ischemia. However, the mechanism and consequences of this phenomenon are not clear. We investigated whether this suppressed endogenous ADO production could be reversed by a transient supply of exogenous ADO during reperfusion. Furthermore, we studied the recovery of mechanical function, coronary flow and myocardial nucleotide levels after this intervention. Three concentrations of ADO were applied: 1 microM, which exerts maximal vasodilatation: 30 microM, optimal for adenylate resynthesis: and 1 mM which exerts a cardioplegic effect. Rat hearts perfused in the Langendorff mode were divided into five groups (n = 6-9 per group): all hearts had transient (30-s) ischemia at 20 min (TI-1) and 70 min (TI-3) of perfusion. Group 1 (control) had an additional transient (30-s) ischemia at 45 min (TI-2). Group 2 (ischemic control) had 10-min ischemia at 30 min: groups 3, 4 and 5 also had 10-min ischemia at 30 min but were reperfused for the initial 15 min with 1 microM, 30 microM or 1 mM ADO. Developed tension, coronary flow and coronary effluent purines and pyrimidines were measured throughout the 75-min experimental period. Nucleotide content was evaluated in freeze-clamped hearts at the end of the experiment. Endogenous ADO release to the coronary effluent increased immediately after TI-1 in all groups. This increase was similar after TI-1 and after TI-3 in control, while it was reduced to 30% in ischemic control group. In the 30 microM ADO group the increase in endogenous ADO release after TI-3 was restored and was similar to that after TI-1. A similar trend was observed with 1 mM ADO, while in 1 microM group recovery of endogenous ADO release after TI-3 was not observed. The highest recovery of developed tension (+ S.E.) occurred with 1 microM and 30 microM ADO (72 +/- 3% and 72 +/- 5% of pre-ischemic value, respectively) compared to 53 +/- 5% and 63 +/- 5% in ischemic control and 1 mM ADO groups, respectively (P <0.05). Coronary flow was restored 30 s after 10 min ischemia in hearts treated with 1 microM and 30 microM ADO, whereas more than 2 min were necessary in ischemic control or 1 mM ADO groups. Furthermore, hyperemic response after TI-3 was significantly enhanced in the 1 microM or 30 microM ADO groups. ATP content at the end of reperfusion was highest in the 30 microM ADO group (18.9 +/- 0.5 micromol/g dry wt.) as compared to ischemic control. 1 microM or 1 mM ADO groups (15.2 +/- O.6, 16.4 +/- 0.4, and 17.2 +/- 0.4 micromol/g dry wt. respectively). Concentrations of other nucleotide triphosphates (GTP, UTP and CTP) were similar in all hearts subjected to 10-min ischemia. In summary, depressed endogenous ADO production in the post-ischemic heart could be ameliorated by transient supply of exogenous ADO during reperfusion at 30 microM concentration. This effect was found to be related to the elevation of the adenine nucleotide pool. However, restoration of endogenous ADO production was not necessary for improvement in the recovery of mechanical function by exogenous ADO.

Patients who make a dentist most anxious about giving injections.

The patient is not the only person in the dental operatory who may be feeling anxious about injections. A questionnaire mailed to 3,000 alumni of a California dental school of study the effects on dentists of administering local anesthesia showed that they, too, can be anxious during the procedure. Of the 3,000 questionnaires sent out, 711 valid ones were returned. This paper analyzes the answers of 545 respondents to one of the questionnaire's open-ended questions, "Is there one type of patient that seems to make you the most anxious about giving injections? If so, please describe this type of patient." Two-thirds of the responses to this question described anxious patients as the main source of the dentist's anxiety. The next most frequent response (16 percent) identified children as the main source of anxiety. Six percent of the dentists wrote that no particular type of patient bothers them when giving an injection.

The injection procedure as a source of stress for dentists.

A questionnaire was mailed to 3,000 practicing dentists to inquire about their physical and psychological responses to injecting local anesthesia; 711 dentists completed questionnaires (a 24 percent response rate). Six percent of respondents considered their thoughts and feelings associated with injection to be a serious problem; two percent reported no negative reactions to this aspect of clinical practice. Reported reactions to various anesthetic procedures were compared, and the various responses are discussed. Injection of local anesthesia, rarely discussed in the literature, contributes significantly to overall stress of dentists, but not all dentists.

Analysis of CAG trinucleotide repeats from mouse cDNA sequences.

A number of human single gene disorders are now known to result from abnormal expansion of trinucleotide repeats. Spinal muscular bulbar atrophy, myotonic dystrophy, Huntington's Disease, spinocerebellar ataxia and dentatorubral-pallidoluysian atrophy are all caused by expansions of CAG repeats. Abnormal expansion of trinucleotide repeats has only so far been described in humans, and no mouse models exist for these diseases. In order to investigate trinucleotide repeat stability in mice, the Genbank and EMBL nucleotide databases were screened to find genes containing CAG repeats. Of the sequences selected, 32 were from mouse, and in 12 of these the repeat was in transcribed sequence and contained at least seven perfect repeats. These repeats were then analysed by PCR to evaluate the degree of variability of repeat length in the various genes. Two of the genes containing variable length CAG repeats, seven in absentia homologue 1b (Sinh1b), and choline acetyl transferase (Chat), which had not previously been mapped in the mouse genome, were mapped by linkage analysis in an interspecific backcross. Sinh1b maps very distally on the X chromosome, and Chat maps to chromosome 14.

Long-term preservation of the heart: the effect of infusion pressure during continuous hypothermic cardioplegia.

Continuous hypothermic low-flow infusion of cardioplegic or other preservation solutions has been advocated for extending the maximum duration of storage of donor hearts for transplantation. We report the effect of varying the pressure during continuous infusion of St. Thomas' Hospital cardioplegic solution on functional recovery after long-term storage. Isolated working rat hearts (six per group) were aerobically perfused (20 minutes), and control indexes of cardiac function were measured; hypothermic ischemic arrest was then induced by a 3-minute infusion (60 cm H2O) of cold (7.5 degrees C) St. Thomas' Hospital cardioplegic solution. Hearts were then stored for 8 hours at 7.5 degrees C, either immersed in St. Thomas' Hospital cardioplegic solution (noninfused control) or continuously infused at varying infusion pressures with St. Thomas' Hospital cardioplegic solution, which had been both oxygenated and supplemented by the addition of glucose (11.1 mmol/L). After 8 hours of hypothermic ischemia, the rate of cardioplegic infusion was measured as an index of vascular resistance. The hearts were then reperfused (Langendorff) for 30 minutes during which creatine kinase leakage was measured. The hearts were then converted to working preparations for 20 minutes, and the recovery of contractile function was measured and expressed as a percentage of the preischemic control value. In hearts that had been subjected to continuous infusion at 6, 10, 20, 30, 40, and 60 cm H2O, the recoveries of aortic flow were 0% (p less than 0.05), 38.6% +/- 5.1% (p less than 0.05), 36.2% +/- 3.6% (p less than 0.05), 14.0% +/- 8.0%, 5.8% +/- 2.9%, and 9.9% +/- 4.7%, respectively, and the postischemic leakage of creatine kinase was 98.7 +/- 19.5 (p less than 0.05), 26.2 +/- 4.2, 15.5 +/- 3.4, 30.4 +/- 11.1, 109.8 +/- 21.8 (p less than 0.05), and 136.0 +/- 14.1 (p less than 0.05) IU/30 min/gm dry weight, respectively. In contrast, in noninfused control hearts the recovery of aortic flow was 11.1% +/- 7.5%, and creatine kinase leakage was 58.9 +/- 8.7 IU/30 min/gm dry weight. In conclusion, maximum myocardial preservation was obtained with continuous low-flow hypothermic cardioplegic infusion at pressures between 10 and 20 cm H2O.

Estimation of long-term risk from Canadian uranium mill tailings.

A methodology is presented for assessing the risk from Canadian uranium mill tailings piles. The methodology is based on the "set of triplets" concept and uses an event tree to identify various scenarios representing the performance of a pile over its 1,000-year design life. Compartment-type mathematical models are used to quantify the movement of hazardous substances through the environment. Numerical examples are given of both "level 1" (straight probabilistic) and "level 2" (probability of frequency) type analyses.

Supravalvular aortic stenosis-infantile hypercalcaemia syndrome: in vitro hypersensitivity to vitamin D2 and calcium.

The incidence of cytoplasmic metachromasia has been studied in cultures of skin fibroblasts derived from 6 cases of the syndrome of supravalvular aortic stenosis, characteristic facies, and mental retardation which in many instances represents the late normocalcaemic stage of the severe form of infantile hypercalcaemia. The percentage of metachromatic cells (mean positivity 7.3%) was significantly higher than in control cultures. The addition of vitamin D2 and calcium to culture media caused a highly significant increase in metachromatic cells (mean positivity in supplemented media 16.1%) compared with a lesser increase in controls. These findings strengthen previous suggestions that there is a genetically determined hypersensitivity to vitamin D in some cases of the syndrome. A multifactorial aetiology is proposed, dependent on a variable genetic susceptibility of fetal connective tissues to a non-physiological effect of D vitamins and a variable level of maternal vitamin D nutrition.