Validation of the finding of hypertrophy of the clava in infantile neuroaxonal dystrophy/PLA2G6 by biometric analysis.

INTRODUCTION: Infantile neuroaxonal dystrophy (INAD), an autosomal recessive neurodegenerative disorder due to PLA2G6 mutation, is classified both as a PLA2G6-associated neurodegeneration (PLAN) disorder and as one of the neurodegeneration with brain iron accumulation (NBIA) disorders. Age of onset and clinical presentation in INAD is variable. Typically described imaging features of cerebellar atrophy, cerebellar cortex bright FLAIR signal, and globus pallidus iron deposition are variable or late findings. We characterize clinical and neuroimaging phenotypes in nine children with confirmed PLA2G6 mutations and show a useful imaging feature, clava hypertrophy, which may aid in earlier identification of patients. Measurements of the clava confirm actual enlargement, rather than apparent enlargement due to volume loss of the other brain stem structures. METHODS: A retrospective clinical and MRI review was performed. Brain stem measurements were performed and compared with age-matched controls. RESULTS: We identified nine patients, all with novel PLA2G6 gene mutations. MRI, available in eight, showed clava hypertrophy, regardless of age or the absence of other more typically described neuroimaging findings. Brain autopsy in our cohort confirmed prominent spheroid bodies in the clava nuclei. CONCLUSION: Clava hypertrophy is an important early imaging feature which may aid in indentification of children who would benefit from specific testing for PLA2G6 mutations.

Glutamine and hyperammonemic crises in patients with urea cycle disorders.

UNLABELLED: Blood ammonia and glutamine levels are used as biomarkers of control in patients with urea cycle disorders (UCDs). This study was undertaken to evaluate glutamine variability and utility as a predictor of hyperammonemic crises (HACs) in UCD patients. METHODS: The relationships between glutamine and ammonia levels and the incidence and timing of HACs were evaluated in over 100 adult and pediatric UCD patients who participated in clinical trials of glycerol phenylbutyrate. RESULTS: The median (range) intra-subject 24-hour coefficient of variation for glutamine was 15% (8-29%) as compared with 56% (28%-154%) for ammonia, and the correlation coefficient between glutamine and concurrent ammonia levels varied from 0.17 to 0.29. Patients with baseline (fasting) glutamine values >900 µmol/L had higher baseline ammonia levels (mean [SD]: 39.6 [26.2]µmol/L) than patients with baseline glutamine ≤ 900 µmol/L (26.6 [18.0]µmol/L). Glutamine values >900 µmol/L during the study were associated with an approximately 2-fold higher HAC risk (odds ratio [OR]=1.98; p=0.173). However, glutamine lost predictive significance (OR=1.47; p=0.439) when concomitant ammonia was taken into account, whereas the predictive value of baseline ammonia ≥ 1.0 upper limit of normal (ULN) was highly statistically significant (OR=4.96; p=0.013). There was no significant effect of glutamine >900 µmol/L on time to first HAC crisis (hazard ratio [HR]=1.14; p=0.813), but there was a significant effect of baseline ammonia ≥ 1.0 ULN (HR=4.62; p=0.0011). CONCLUSIONS: The findings in this UCD population suggest that glutamine is a weaker predictor of HACs than ammonia and that the utility of the predictive value of glutamine will need to take into account concurrent ammonia levels.

A randomized, placebo-controlled, double-blind study of sapropterin to treat ADHD symptoms and executive function impairment in children and adults with sapropterin-responsive phenylketonuria.

Symptoms of attention deficit-hyperactivity disorder (ADHD), particularly inattention, and impairments in executive functioning have been reported in early and continuously treated children, adolescents, and adults with phenylketonuria (PKU). In addition, higher blood phenylalanine (Phe) levels have been correlated with the presence of ADHD symptoms and executive functioning impairment. The placebo-controlled PKU ASCEND study evaluated the effects of sapropterin therapy on PKU-associated symptoms of ADHD and executive and global functioning in individuals who had a therapeutic blood Phe response to sapropterin therapy. The presence of ADHD inattentive symptoms and executive functioning deficits was confirmed in this large cohort of 206 children and adults with PKU, of whom 118 responded to sapropterin therapy. In the 38 individuals with sapropterin-responsive PKU and ADHD symptoms at baseline, sapropterin therapy resulted in a significant improvement in ADHD inattentive symptoms in the first 4 weeks of treatment, and improvements were maintained throughout the 26 weeks of treatment. Sapropterin was well-tolerated with a favorable safety profile. The improvements in ADHD inattentive symptoms and aspects of executive functioning in response to sapropterin therapy noted in a large cohort of individuals with PKU indicate that these symptoms are potentially reversible when blood Phe levels are reduced.

Elevated phenylacetic acid levels do not correlate with adverse events in patients with urea cycle disorders or hepatic encephalopathy and can be predicted based on the plasma PAA to PAGN ratio.

BACKGROUND: Phenylacetic acid (PAA) is the active moiety in sodium phenylbutyrate (NaPBA) and glycerol phenylbutyrate (GPB, HPN-100). Both are approved for treatment of urea cycle disorders (UCDs) - rare genetic disorders characterized by hyperammonemia. PAA is conjugated with glutamine in the liver to form phenylacetyleglutamine (PAGN), which is excreted in urine. PAA plasma levels ≥ 500 µg/dL have been reported to be associated with reversible neurological adverse events (AEs) in cancer patients receiving PAA intravenously. Therefore, we have investigated the relationship between PAA levels and neurological AEs in patients treated with these PAA pro-drugs as well as approaches to identifying patients most likely to experience high PAA levels. METHODS: The relationship between nervous system AEs, PAA levels and the ratio of plasma PAA to PAGN were examined in 4683 blood samples taken serially from: [1] healthy adults [2], UCD patients of ≥ 2 months of age, and [3] patients with cirrhosis and hepatic encephalopathy (HE). The plasma ratio of PAA to PAGN was analyzed with respect to its utility in identifying patients at risk of high PAA values. RESULTS: Only 0.2% (11) of 4683 samples exceeded 500 µg/ml. There was no relationship between neurological AEs and PAA levels in UCD or HE patients, but transient AEs including headache and nausea that correlated with PAA levels were observed in healthy adults. Irrespective of population, a curvilinear relationship was observed between PAA levels and the plasma PAA:PAGN ratio, and a ratio>2.5 (both in µg/mL) in a random blood draw identified patients at risk for PAA levels>500 µg/ml. CONCLUSIONS: The presence of a relationship between PAA levels and reversible AEs in healthy adults but not in UCD or HE patients may reflect intrinsic differences among the populations and/or metabolic adaptation with continued dosing. The plasma PAA:PAGN ratio is a functional measure of the rate of PAA metabolism and represents a useful dosing biomarker.

Early-onset LBSL: how severe does it get?

AIM: Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is known as a relatively mild leukoencephalopathy. We investigated the occurrence of severe variants of LBSL with extensive brain magnetic resonance imaging (MRI) abnormalities. METHOD: MRIs of approximately 3,000 patients with an unknown leukoencephalopathy were retrospectively reviewed for extensive signal abnormalities of the cerebral and cerebellar white matter, posterior limb of the internal capsule, cerebellar peduncles, pyramids, and medial lemniscus. Clinical data were retrospectively collected. RESULTS: Eleven patients fulfilled the MRI criteria (six males); six had DARS2 mutations. Clinical and laboratory findings did not distinguish between patients with and without DARS2 mutations, but MRI did. Patients with DARS2 mutations more often had involvement of structures typically affected in LBSL, including decussatio of the medial lemniscus, anterior spinocerebellar tracts, and superior and inferior cerebellar peduncles. Also, involvement of the globus pallidus was associated with DARS2 mutations. Earliest disease onset was neonatal; earliest death at 20 months. INTERPRETATION: This study confirms the occurrence of early infantile, severe LBSL, extending the known phenotypic range of LBSL. Abnormality of specific brainstem tracts and cerebellar peduncles are MRI findings that point to the correct diagnosis.

Urinary phenylacetylglutamine as dosing biomarker for patients with urea cycle disorders.

UNLABELLED: We have analyzed pharmacokinetic data for glycerol phenylbutyrate (also GT4P or HPN-100) and sodium phenylbutyrate with respect to possible dosing biomarkers in patients with urea cycle disorders (UCD). STUDY DESIGN: These analyses are based on over 3000 urine and plasma data points from 54 adult and 11 pediatric UCD patients (ages 6-17) who participated in three clinical studies comparing ammonia control and pharmacokinetics during steady state treatment with glycerol phenylbutyrate or sodium phenylbutyrate. All patients received phenylbutyric acid equivalent doses of glycerol phenylbutyrate or sodium phenylbutyrate in a cross over fashion and underwent 24-hour blood samples and urine sampling for phenylbutyric acid, phenylacetic acid and phenylacetylglutamine. RESULTS: Patients received phenylbutyric acid equivalent doses of glycerol phenylbutyrate ranging from 1.5 to 31.8 g/day and of sodium phenylbutyrate ranging from 1.3 to 31.7 g/day. Plasma metabolite levels varied widely, with average fluctuation indices ranging from 1979% to 5690% for phenylbutyric acid, 843% to 3931% for phenylacetic acid, and 881% to 1434% for phenylacetylglutamine. Mean percent recovery of phenylbutyric acid as urinary phenylacetylglutamine was 66.4 and 69.0 for pediatric patients and 68.7 and 71.4 for adult patients on glycerol phenylbutyrate and sodium phenylbutyrate, respectively. The correlation with dose was strongest for urinary phenylacetylglutamine excretion, either as morning spot urine (r = 0.730, p < 0.001) or as total 24-hour excretion (r = 0.791 p<0.001), followed by plasma phenylacetylglutamine AUC(24-hour), plasma phenylacetic acid AUC(24-hour) and phenylbutyric acid AUC(24-hour). Plasma phenylacetic acid levels in adult and pediatric patients did not show a consistent relationship with either urinary phenylacetylglutamine or ammonia control. CONCLUSION: The findings are collectively consistent with substantial yet variable pre-systemic (1st pass) conversion of phenylbutyric acid to phenylacetic acid and/or phenylacetylglutamine. The variability of blood metabolite levels during the day, their weaker correlation with dose, the need for multiple blood samples to capture trough and peak, and the inconsistency between phenylacetic acid and urinary phenylacetylglutamine as a marker of waste nitrogen scavenging limit the utility of plasma levels for therapeutic monitoring. By contrast, 24-hour urinary phenylacetylglutamine and morning spot urine phenylacetylglutamine correlate strongly with dose and appear to be clinically useful non-invasive biomarkers for compliance and therapeutic monitoring.

Ammonia control in children with urea cycle disorders (UCDs); phase 2 comparison of sodium phenylbutyrate and glycerol phenylbutyrate.

UNLABELLED: Twenty four hour ammonia profiles and correlates of drug effect were examined in a phase 2 comparison of sodium phenylbutyrate (NaPBA) and glycerol phenylbutyrate (GPB or HPN-100), an investigational drug being developed for urea cycle disorders (UCDs). STUDY DESIGN: Protocol HPN-100-005 involved open label fixed-sequence switch-over from the prescribed NaPBA dose to a PBA-equimolar GPB dose with controlled diet. After 7 days on NaPBA or GPB, subjects underwent 24-hour blood sampling for ammonia and drug metabolite levels as well as measurement of 24-hour urinary phenyacetylglutamine (PAGN). Adverse events (AEs), safety labs and triplicate ECGs were monitored. RESULTS: Eleven subjects (9 OTC, 1 ASS, 1 ASL) enrolled and completed the switch-over from NaPBA (mean dose=12.4 g/d or 322 mg/kg/d; range=198-476 mg/kg/d) to GPB (mean dose=10.8 mL or 0.284 mL/kg/d or 313 mg/kg/d; range=192-449 mg/kg/d). Possibly-related AEs were reported in 2 subjects on NaPBA and 4 subjects on GPB. All were mild, except for one moderate AE of vomiting on GPB related to an intercurrent illness. No clinically significant laboratory or ECG changes were observed. Ammonia was lowest after overnight fast, peaked postprandially in the afternoon to early evening and varied widely over 24h with occasional values >100 µmol/L without symptoms. Ammonia values were ~25% lower on GPB vs. NaPBA (p≥0.1 for ITT and p<0.05 for per protocol population). The upper 95% confidence interval for the difference between ammonia on GPB vs. NaPBA in the ITT population (95% CI 0.575, 1.061; p=0.102) was less than the predefined non-inferiority margin of 1.25 and less than 1.0 in the pre-defined per-protocol population (95% CI 0.516, 0.958; p<0.05). No statistically significant differences were observed in plasma phenylacetic acid and PAGN exposure during dosing with GPB vs. NaPBA, and the percentage of orally administered PBA excreted as PAGN (66% for GPB vs. 69% for NaPBA) was very similar. GPB and NaPBA dose correlated best with urinary-PAGN. CONCLUSIONS: These findings suggest that GPB is at least equivalent to NaPBA in terms of ammonia control, has potential utility in pediatric UCD patients and that U-PAGN is a clinically useful biomarker for dose selection and monitoring.

Genotype-phenotype correlation in vanishing white matter disease.

OBJECTIVE: Vanishing white matter (VWM) is an autosomal recessive leukoencephalopathy characterized by slowly progressive ataxia and spasticity with additional stress-provoked episodes of rapid and major deterioration. The disease is caused by mutations in the genes encoding the subunits of eukaryotic initiation factor 2B, which is pivotal in translation of mRNAs into proteins. The disease onset, clinical severity, and disease course of VWM vary greatly. The influence of genotype and gender on the phenotype is unclear. METHODS: From our database of 184 patients with VWM, we selected those with the following mutations in the gene EIF2B5: p.Arg113His in the homozygous state (n = 23), p.Arg113His in the compound-heterozygous state (n = 49), p.Thr91Ala in the homozygous state (n = 8), p.Arg113His/p.Arg339any (n = 9), and p.Thr91Ala/p.Arg339any (n = 7). We performed a cross-sectional observational study. Evaluated clinical characteristics were gender, age at onset, age at loss of walking without support, and age at death. Means, male/female ratios, and Kaplan-Meier curves were compared. RESULTS: Patients homozygous for p.Arg113His had a milder disease than patients compound heterozygous for p.Arg113His and patients homozygous for p.Thr91Ala. Patients with p.Arg113His/p.Arg339any had a milder phenotype than patients with p.Thr91Ala/p.Arg339any. Overall, females tended to have a milder disease than males. CONCLUSIONS: The clinical phenotype in VWM is influenced by the combination of both mutations. Females tend to do better than males.

Pyruvate dehydrogenase phosphatase 1 (PDP1) null mutation produces a lethal infantile phenotype.

Pyruvate dehydrogenase phosphatase deficiency has previously only been confirmed at the molecular level in two brothers and two breeds of dog with exercise intolerance. A female patient, who died at 6 months, presented with lactic acidemia in the neonatal period with serum lactate levels ranging from 2.5 to 17 mM. Failure of dichloroacetate to activate the PDH complex in skin fibroblasts was evident, but not in early passages. A homozygous c.277G > T (p.E93X) nonsense mutation in the PDP1 gene was identified in genomic DNA and immunoblotting showed a complete absence of PDP1 protein in mitochondria. Native PDHC activity could be restored by the addition of either recombinant PDP1 or PDP2. This highlights the role of PDP2, the second phosphatase isoform, in PDP1-deficient patients for the first time. We conclude that the severity of the clinical course associated with PDP1 deficiency can be quite variable depending on the exact nature of the molecular defect.

A novel mitochondrial DNA mutation in COX1 leads to strokes, seizures, and lactic acidosis.

Cytochrome c oxidase (COX) is the terminal enzyme of the respiratory chain, with subunits originating both from the mitochondrial and nuclear genome. An eleven-year-old female presented initially with a seizure followed two months later with tonic-clonic seizures, weakness and aphasia. MRI of the cerebral hemispheres showed multiple infarcts. Previous history suggested gross and fine motor control deficits with learning difficulties. A muscle biopsy showed a specific decrease of COX staining in all fibres and pleomorphic mitochondria. Respiratory chain studies confirmed an isolated complex IV defect in muscle, whilst fibroblasts showed an initial COX activity below normal which rapidly came up to the normal range on culture. Sequencing of mtDNA revealed an heteroplasmic m.7023G>A mutation in the COX1 gene, with levels of 96% in muscle, 70% in blood and 50% in the initial skin fibroblast culture dropping to 10% in later passages. The mutation was present in a critical region of the COX1 gene, the V374M change being close to the two histidine residues His376 and His378 co-ordinating with the heme a and a (3), and His367 which co-ordinates a magnesium ion. This case highlights that a MELAS-like syndrome can occur with isolated COX deficiency.

Sorption of aroma compounds in PET and PVC during the storage of a strawberry syrup.

The sorption of 14 aroma compounds into PET and PVC was monitored during storage of a strawberry syrup for 1 year. Concentrations in the syrup and in the polymer were determined during storage and compared with previously published results obtained with glass bottles. Apparent partition coefficients between the polymer and the syrup (noted K app) were estimated from experimental kinetics without reaching equilibrium K app values and optimally identified from the kinetic data obtained between 30 and 90 days. They exhibited a similar behaviour for both polymers with values were between 2 x 10(-5) and 2 x 10(-3), 4 x 10(-5) and 3 x 10(-2), respectively, for PET and PVC. The variation of K app values in PET was mainly correlated to the polarity of tested compounds as assessed by their log P values. By contrast, the variations in K app values for PVC were mainly related to their chain lengths. Due to slightly higher partition coefficients and diffusion coefficients in PVC compared with PET, the amount of absorbed aroma was four times higher in PVC than in PET; however, the amount of absorbed aroma compounds was less than 0.1% of the initial amount present into the syrup, except for octyl butanoate. The variation in concentration in the syrup was interpreted as a combination of a degradation process and a transport process into the packaging material. Both effects were particularly noticeable for both PET and unstable aroma compounds.

Hypomyelination with atrophy of the basal ganglia and cerebellum: follow-up and pathology.

BACKGROUND AND OBJECTIVE: Hypomyelination with atrophy of the basal ganglia and cerebellum is a recently defined disorder. Only a few patients have been described. We report on 11 additional patients and new MRI findings and provide histopathologic confirmation of the MRI interpretation. METHODS: We reviewed the patients' clinical history and present findings. We scored the MRI abnormalities. The histopathology of one patient was re-examined. RESULTS: The patients' early psychomotor development was normal or delayed, followed by increasing extrapyramidal movement abnormalities, ataxia, and spasticity. Mental capacities were variably affected. MRI showed hypomyelination with, on follow-up, evidence of further myelin loss and variable white matter atrophy. The putamen was small or, more often, absent; the head of the caudate nucleus was decreased in size. In contrast, the thalamus and globus pallidus remained normal. Cerebellar atrophy was invariably present. Histopathology confirmed the myelin deficiency, probably related to both lack of deposition and low-grade further loss. The degeneration of putamen was subtotal. The cerebellar cortex was affected, particularly the granular layer. CONCLUSION: Hypomyelination with atrophy of the basal ganglia and cerebellum is a syndrome diagnosed by distinctive MRI findings. Histopathology confirms hypomyelination, low-grade further myelin loss, subtotal degeneration of the putamen, and cerebellar cortical atrophy. All known patients are sporadic, and the mode of inheritance is unclear.

Modelling of migration from multi-layers and functional barriers: estimation of parameters.

Functional barriers form parts of multi-layer packaging materials, which are deemed to protect the food from migration of a broad range of contaminants, e.g. those associated with reused packaging. Often, neither the presence nor the identity of the contaminants is known, so that safety assessment of the materials has to rely on predictive tools. Several complementary freeware described here allow one to model diffusion in multi-layer films. These tools require the input of parameters that are not easy to determine or predict. Previous work has focused on the prediction of diffusion coefficients at storage temperatures of packaging in contact with food. However, many other kinetic and thermodynamic parameters are needed to describe transport properties during the processing of a material at high temperature and during its shelf-life. All parameters needed for the calculations are discussed. In order to propose default values, the approach consists of (1) reviewing the available literature data, (2) running experiments on polypropylene, polyethylene and poly(ethylene vinyl alcohol) in typical conditions (separately diffusion during processing and migration) and (3) simulating numerical sets for typical situations. Several freeware are proposed to simulate migration from multi-layers and functional barriers using the default parameters.

A study on the nature of genetic metabolic practice at a major paediatric referral centre.

A retrospective chart review of new paediatric patients seen during the calendar year 1998 by specialists of the Division of Clinical and Metabolic Genetics of the Hospital for Sick Children in Toronto, the largest such referral centre in the country, showed that 81% of specific genetic metabolic diagnoses were made within one month of being seen in consultation by one of the consultants of the programme. In 5% of cases, a specific diagnosis was not reached 4 years after initial consultation. We concluded from this study that the specific diagnosis of inborn errors of metabolism at a major medical genetic referral centre tended to be made quickly, or never. Some of the causes of delays in diagnosis include (1) the lack of ready access to existing diagnostic laboratory testing; (2) technical barriers to the identification of specific metabolic or genetic defects; and (3) incomplete knowledge of genetic defects causing inherited metabolic diseases.

Atypical phenotype in a boy with a maple syrup urine disease.

Maple syrup urine disease (MSUD) is a metabolic disorder due to a block in the decarboxylation step in the catabolic pathways of the branched-chain amino acids (BCAAs). We describe an atypical presentation in an infant male. The patient presented with psychomotor retardation, profound hypotonia and elevated plasma levels of BCAAs, but no elevation of alloisoleucine. Cranial magnetic resonance imaging showed prominent diffuse CSF spaces, delayed myelin maturation and symmetrical signal abnormality within the globi pallidi, midbrain, dorsal pons and medulla. The cerebellar white matter was specifically spared. A mitochondrial disorder was suggested. After correction of feeding problems with G-tube feeds, his high BCAAs persisted and, on fourth analysis, alloisoleucine was seen. Subsequent fibroblast enzyme and mutation analysis confirmed MSUD due to E(1)-alpha subunit deficiency. After starting dietary treatment, there was no significant improvement in his hypotonia or his psychomotor development. However, the high signal within the globi pallidi had resolved. MSUD may have diverse clinical presentations, and should be considered in children who present with chronic psychomotor delay but no acute encephalopathic episodes. BCAA levels may not be very high, alloisoleucine may not always be detected in MSUD even with severe enzyme deficiency, and imaging may be misleading if seen in the chronic phase only.

Functional barriers: properties and evaluation.

Functional barriers are multilayer structures deemed to prevent migration of some chemicals released by food-contact materials into food. In the area of plastics packaging, different migration behaviours of mono- and multilayer structures are assessed in terms of lag time and of their influence of the solubility of the migrants in food simulants. Whereas barriers to oxygen or to aromas must prevent the diffusion of these compounds under conditions of use, a functional barrier must also be efficient under processing conditions, to prevent diffusion of substances when the polymer layers are in contact at high (processing) temperatures. Diffusion in melted polymers at high temperatures is much slower for glassy polymers, than in polymers that are rubbery at ambient temperature. To evaluate the behaviour of functional barriers under conditions of use, a set of reference diffusion coefficients in the 40-60 degrees C range were determined for 14 polymers. Conditions for accelerated migration tests are proposed based on worst-case activation energy in the 40-60 degrees C range. For simulation of migration, numerical models are available. The rules derived from the models can be used both by industry (to optimize a material in terms of migration) or by risk assessors. Differences in migration behaviour between mono- and multilayer materials are discussed.

Evaluation of migration models that might be used in support of regulations for food-contact plastics.

Materials and articles intended to come into contact with food must be shown to be safe because they might interact with food during processing, storage and the transportation of foodstuffs. Framework Directive 89/109/EEC and its related specific Directives provide this safety basis for the protection of the consumer against inadmissible chemical contamination from food-contact materials. Recently, the European Commission charged an international group of experts to demonstrate that migration modelling can be regarded as a valid and reliable tool to calculate 'reasonable worst-case' migration rates from the most important food-contact plastics into the European Union official food simulants. The paper summarizes the main steps followed to build up and validate a migration estimation model that can be used, for a series of plastic food-contact materials and migrants, for regulatory purposes. Analytical solutions of the diffusion equation in conjunction with an 'upper limit' equation for the migrant diffusion coefficient, D(P), and the use of 'worst case' partitioning coefficients K(P,F) were used in the migration model. The results obtained were then validated, at a confidence level of 95%, by comparison with the available experimental evidence. The successful accomplishment of the goals of this project is reflected by the fact that in Directive 2002/72/EC, the European Commission included the mathematical modelling as an alternative tool to determine migration rates for compliance purposes.

Mechanism of migration from agglomerated cork stoppers. Part 2: Safety assessment criteria of agglomerated cork stoppers for champagne wine cork producers, for users and for control laboratories.

Producers of cork for champagne and wine have to be certain the corks meet the requirements of the European Union Framework Directive, and comply with the evaluations of chemicals carried out in the European Union. To identify chemicals in cork with the potential to migrate, the different synthetic products on the market were classified based on their technical role and of the chemistry involved. The potential migrants in each class (adhesive for cork bodies, adhesive for cork disks, lubricants and surface treatments) were analysed spectroscopically and chromatographically. A general approach was proposed for the evaluation of each commercial chemical: the detailed composition was supplied and verified mainly by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy ((1)H-NMR) and GC-MS. A procedure to determine primary aromatic amines, specifically for cork migrates, based on GC-MS was developed. These techniques focussed on migrants below 1000 g mol(-1), as higher molecular weight chemicals are not likely to pose a problem for public health. The products were also tested after polymerization. The analytical scheme included an analytical check of synthetic product formulation and identification of potential migrants, solvent extraction and analysis of cork extracts.

Tailoring fatty food simulants made from solvent mixtures (2): determining the equivalent migration behaviour of olive oil and of solvents in the case of polyolefins.

It is suggested that solvent mixtures consisting of an ester and of an inert solvent can be used as fatty food simulants capable of having the same migration behaviour as olive oil with plastics. Migration tests carried out with low-density polyethylene for 20 and 48 h in an 8 and 5% mixture of tert-butyl acetate in ethanol respectively gave results equivalent to those obtained with olive oil after 10 days at 40 degrees C. The use of solvent mixtures facilitated the analysis and improved detection limits, giving good repeatability. Furthermore, the more rapid migration in solvent mixtures can be particularly useful for industrial controls as alternative test methods.

Integrated approach of migration prediction using numerical modelling associated to experimental determination of key parameters.

The principle of utilizing a computing program describing precisely the migration of additives from a polymer into a food simulant is presented. The model has been validated with a UV absorber in polypropylene migrating into glyceryl tripelargonate, a pure triglyceride whose behaviour and average molecular weight are similar to Myglyol (a synthetic mixture of C8-C12 triglycerides). Six parameters were used to fit the simulant sorption and additive extraction kinetics, and these were determined by independent experiments. The possibility of eliminating any of the parameters is also discussed. This work provides the first consistent set of experimental data that can be used to overestimate the diffusion coefficients of additives both in virgin (without contact with solvent) and in swollen (fat contact) polymer. The influence of mobility increase brought out by temperature or swelling are compared. The effects were more important for high molecular weight compounds.