Examining outpatients' hand hygiene behaviour and its relation to COVID-19 infection prevention measures

BACKGROUND

The increasing demand for outpatient care is associated with a higher risk of infection transmission in these settings. However, there is limited research on infection prevention and control practices in ambulatory clinics, and none focuses on patients.

AIM

To examine outpatients' hand hygiene behaviours, their determinants, and their associations with other infection prevention measures during the COVID-19 pandemic.

METHODS

We observed the hand hygiene behaviour of one cohort of patients in one outpatient clinic and surveyed a separate sample in five clinics about their hand hygiene practice in outpatient facilities. A questionnaire based on the Theoretical Domains Framework (TDF) was used to examine predictors of the behaviour. Moreover, patients indicated their compliance with COVID-19 infection prevention measures, vaccination status, disease risk perception, and vaccine hesitancy.

FINDINGS

Observed hand hygiene rates among 618 patients were low (12.8%), while 67.3% of the 300 surveyed patients indicated sanitizing their hands upon entering the clinic. The TDF domains 'memory, attention, and decision processes' and 'emotions' significantly predicted both current (today's) and general hand hygiene behaviour in outpatient clinics. Hand hygiene behaviour and compliance with COVID-19 infection prevention showed a positive association; however, no significant connection was found with patients' vaccination status, suggesting different behavioural motivators.

CONCLUSION

Hand hygiene among outpatients should be improved through interventions focusing on helping patients remember to clean their hands. More research on infection prevention in outpatient facilities is needed to ensure patient safety.

The impact of home-delivered meal services on the nutritional intake of community living older adults: a systematic literature review

BACKGROUND

There is a global increase in populations aged over 65 years. Physiological changes that occur during ageing may increase the nutritional risk for older adults. To avoid malnutrition and address some of the barriers to obtain an adequate food supply, home-delivered meals services provide meals in the home or in congregate settings for older adults who require nutritional support.

METHODS

This systematic literature review explored whether nutritional intake is improved in community-living older adults when receiving meal services compared to when meal services are not received. Four electronic databases were searched up to 31 January 2019. In total, 13 original studies were included in this analysis with the components: intervention of home-delivered meal or congregate meal services to older adults; comparison with groups not receiving meal services or days not receiving the meal service; and nutritional intake as an outcome measured by food history, dietary recall and/or food frequency questionnaire.

RESULTS

The results supported a beneficial effect of home-delivered meals on dietary intake of energy, protein and/or certain micronutrients in older adults.

CONCLUSIONS

The increased total energy intake is a positive influence on malnutrition risk in frail older adults and the increased protein intake supports good health, promotes recovery from illness and assists in maintaining functionality in older adults. Additionally, there was a particular increase in calcium intake, which is relevant in ageing, especially for bone health.

eHealth readiness of dietitians

BACKGROUND

The present study aimed to determine the eHealth readiness and changes over time of dietitians in Australia.

METHODS

Two cross-sectional analyses of Australian dietitians were conducted in 2013 and 2016, using a survey adapted from one conducted in 2011 by the US Academy of Nutrition and Dietetics. The survey encompassed 30 questions on eHealth readiness across five dimensions: access, standards, attitude, aptitude and advocacy. Descriptive statistics, independent t-tests, chi-squared tests and Z-tests were computed to compare responses from the 2013 and 2016 surveys.

RESULTS

The survey completion rate represented 14.5% (747) of the Dietitians Association of Australia members in 2013 and 8% (417) in 2016. The survey responses in relation to access and standards suggest that dietitians are well positioned for eHealth. For attitude and aptitude, there is a moderate level of preparedness, with minor improvements over time. Although showing significant improvement (P < 0.05), advocacy highlights the area requiring the most development because the majority of dietitians (61%) reported 'no role' in eHealth solutions.

CONCLUSIONS

Dietitians are progressing in relation to access, attitudinal and aptitudinal readiness for eHealth, although they rate poorly with respect to advocacy readiness. It was concluded that dietitians are not yet ready, and also that valuable opportunities to achieve the benefits that eHealth can deliver will be missed, if dietitians do not take the lead in guiding the development, selection and implementation of nutrition-related technologies. Strengthening the dimension of advocacy and ensuring collaboration across the profession, drawing on the varying expertise demonstrated across the practice areas and by the different generations, will be central to improving dietitian eHealth readiness.

The influence of hydroalcoholic media on the performance of Grewia polysaccharide in sustained release tablets

Co-administration of drugs with alcohol can affect the plasma concentration of drugs in patients. It is also known that the excipients used in the formulation of drugs may not always be resistant to alcohol. This study evaluates effect of varying alcohol concentrations on theophylline release from two grades of Grewia mollis polysaccharides. X-ray microtomography showed that native polysaccharide formulation compacts were not homogenous after the mixing process resulting in its failure in swelling studies. Removal of starch from the native polysaccharide resulted in homogenous formulation compacts resistant to damage in high alcoholic media in pH 6.8 (40%v/v absolute ethanol). Destarched polymer compacts had a significantly higher hardness (375N) than that of the native polysaccharide (82N) and HPMC K4M (146N). Dissolution studies showed similarity at all levels of alcohol tested (f₂=57-91) in simulated gastric media (pH 1.2). The dissolution profiles in the simulated intestinal fluids were also similar (f₂=60-94), with the exception of the native polysaccharide in pH 6.8 (40%v/v absolute ethanol) (f₂=43). This work highlights the properties of Grewia polysaccharide as a matrix former that can resist high alcoholic effects therefore; it may be suitable as an alternative to some of the commercially available matrix formers with wider applications for drug delivery as a cheaper alternative in the developing world.

Accessing hospital packaged foods and beverages: the importance of a seated posture when eating

BACKGROUND

Hospitalised and community dwelling older people (aged 65 years and over) have difficulties opening certain food and beverage items (e.g. cheese portions and tetra packs) served in public hospitals. Previously, the role of hand strength on successful pack opening has been explored in a seated position. However, because many people in hospital eat in bed, the present laboratory study examined the differences between participants opening a selection of products in a hospital bed and a chair.

METHODS

The present study used a qualitative method (satisfaction) and quantitative methods (grip and pinch strength, dexterity, time and attempts) in two conditions (bed; chair) in a sample of well older community dwelling adults (n = 34). Packs tested included foil sealed thickened pudding, foil sealed thickened water, tetra pack, dessert, custard, jam, cereal, honey sachet and cheese portions.

RESULTS

Honey sachets, cheese portions, foil sealed thickened pudding and tetra packs were the most difficult packs to open, with 15% of cheese portions unable to be opened in either the bed or chair posture. Although grip strength was consistent for each posture, pinch grips and dexterity were adversely affected by the bed posture. Lying in a hospital bed required greater pinch strength and dexterity to open packs.

CONCLUSIONS

Eating in a seated position when in hospital has been shown to improve intake. The present study demonstrates that eating in a seated posture is also advantageous for opening the food and beverage packs used in the NSW hospital food service and supports the notion that patients should sit to eat in hospital.

Physiological and Molecular Characterization of Salmonella Bacteriophages Previously Used in Phage Therapy

The use of bacteriophages as biocontrol agents to control Salmonella in food production has gained popularity over the last two decades. Previously, our laboratory demonstrated that bacteriophages can be direct fed to limit Salmonella colonization and transmission in pigs. Here, we characterized the bacteriophages in our treatment cocktail in terms of lytic spectrum, growth kinetics, survivability under various conditions, and genomic sequencing. PCR-based fingerprinting indicated that 9 of the 10 phages, while related, were distinct isolates. Single-step growth kinetics analysis determined that the eclipse periods, latent periods, and burst sizes averaged 21.5 min, 31.5 min, and 43.3 particles, respectively. The viability of the phages was measured after exposure to various pH ranges, temperatures, digestive enzymes, UV light, and chlorinated water. Temperatures greater than 87.5°C, pH of <2.0, UV light (302 and 365 nm), and chlorinated water (500 ppm) inactivated the tested phages. Only select bacteriophages, however, were affected by incubation at temperatures of ≤75.0°C or pH of 4.0 to 10.0. Genomic sequencing of the phage with the broadest spectrum in the collection (effectively lysed all four Salmonella serovars tested), vB_SalM_SJ2, revealed it to belong to the Viunalikevirus genus of the Myoviridae family. Of the 197 predicted open reading frames, no toxin-associated, lysogenic, Salmonella virulence, or antimicrobial resistance genes were identified. Taken together, these data indicate that phages, as biologicals, may require some manner of protection (e.g., microencapsulation) to remain viable under various physiological and manufacturing conditions. In addition, based on its ability to effectively lyse diverse Salmonella serovars, phage vB_SalM-SJ2 could be further developed as an important biocontrol agent in various aspects of food production when the exact serovar or strain of contaminating Salmonella is not yet known.

Evaluation of a pilot volunteer feeding assistance program: influences on the dietary intakes of elderly hospitalised patients and lessons learnt

OBJECTIVES

Malnutrition is a serious concern in hospitals and is known to be associated with increased complications for patients, increased hospital costs and length of stay. Trained volunteers that assist 'at risk' and malnourished patients at lunch meals have been shown to effectively increase nutritional intake in a suburban hospital in Sydney. The pilot study reported here aimed to evaluate and share learnings from a similar, newly implemented program, comparing energy and macronutrient intakes on days with no volunteer assistance, to days with volunteers.

DESIGN

Dietary intakes were determined by visual estimation of meal trays before and after meals, for two days without volunteers, and two days with volunteer assistance at lunch. Macronutrient and energy intakes were compared and data such as weight, height, diet type and medical history were obtained from medical records. Questionnaires were completed by nurses and volunteers in regards to their views and experiences with the program.

SETTING

Hospital based.

RESULTS

Eight patients (83±4.5 years) participated in the study. When volunteers were present at lunch, the average macronutrient and energy intakes increased, though not statistically significantly. The mean increases were 316 kJ (p=0.175) for energy, 3.1 g (p=0.468) for protein, 1.4 g (p=0.418) for fat and 11.6 g (p=0.084) for carbohydrates. Non-significant increases in macronutrients were also noted for the average daily intakes.

CONCLUSION

Although not statistically significant, energy and macronutrient intakes increased when volunteers were present. The implementation of a volunteer feeding assistance program is one strategy to assist dietary intakes but requires a ready team of volunteers, training, acceptance and significant time to develop.

Continuous synthesis of dispersant-coated hydroxyapatite plates

A continuous flow hydrothermal synthetic route which allows the direct “in situ” capping/coating of hydroxyapatite nanoplates with functional dispersants in a single stage is reported.

"It could probably help someone else but not me": a feasibility study of a snack programme offered to meals on wheels clients

OBJECTIVES

Community-based services, such as Meals on Wheels (MOW), allow older adults to remain in their homes for as long as possible. Many MOW recipients experience decreased appetite that limits intake at mealtimes. This pilot study aimed to determine the feasibility of providing high protein high energy snacks to improve nutrient intakes of MOW clients in a regional centre of New South Wales, Australia.

PARTICIPANTS

A convenience sample of 12 MOW clients.

INTERVENTION

Participants received snacks five times a week, in addition to their usual MOW order, for four weeks.

MEASUREMENTS

Nutritional status was assessed using the Mini Nutritional Assessment tool. Pre-post changes in dietary intake were assessed using a diet history and food frequency questionnaire. Qualitative interviews conducted in clients' homes were digitally recorded, transcribed verbatim, and themes identified.

RESULTS

Post-intervention, there was a trend for an increased energy (mean = +415kJ (SD=1477) /day) and protein (+7.2 (±14.06) g/day) intake. MNA scores significantly increased (P= 0.036) and proportion of respondents categorised as 'malnourished' or 'at risk of malnutrition' decreased from 17% to 8%, and 67% to 25%, respectively (P <0.05). Mean body weight increased from 67.1 (±14.3) to 67.8 (±14.8) (P= 0.008), while Body Mass Index (BMI) increased by a mean of 0.78 (±1.16) kg/m2 (P = 0.039). Only half of participants indicated interest in continuing with the program. Reasons included the role of snacks serving as a reminder to eat, as well as their perceived nutritional value. Identified barriers included perceived lack of need for additional food, ability to self-provide such items, and a perceived adequate health status.

CONCLUSION

Provision of an additional daily mid-meal snack may be a useful addition to existing MOW services, for improved energy and protein intakes. However, not all MOW clients at risk of malnutrition perceived the snacks to be beneficial to them.

Accessing packaged food and beverages in hospital. Exploring experiences of patients and staff

Food and beverage packaging has been identified as a contributing factor to malnutrition among elderly patients in hospitals. The focus of this research was to describe the types of food and beverage packaging used in NSW hospitals, determine the 'problematic' packaging from the users' perspective, investigate the effect of hand strength on the ability to open the packaging and to survey users' (patients and staff) views on the 'accessibility' of the packaging. The study was conducted in the Illawarra region of NSW, Australia. Participants (140 mostly elderly inpatients and 64 staff members) were recruited from four local public hospitals. Data were collected using interviews, questionnaires, observations and grip strength testing. Several food and beverage packages were found difficult to open by at least 40% of patients. These included milk and juices (52%), cereal (49%), condiments (46%), tetra packs (40%) and water bottles (40%). The difficulties were attributed to 'fiddly' packaging, hand strength and vision; however, only tetra packs demonstrated a relationship between time taken to open and hand strength, suggesting other aspects of hand function may be more important than strength when opening food and beverage packages.

Magnetic sources of the M50 response are localized to frontal cortex

OBJECTIVE

To determine the source localization(s) of the midlatency auditory magnetic response M50, the equivalent of the P50 potential, a sleep state-dependent waveform known to habituate to repetitive stimulation.

METHODS

We used a paired stimulus paradigm at interstimulus intervals of 250, 500 and 1000 ms, and magnetoencephalographic (MEG) recordings were subjected to computational methods for current density reconstruction, blind source separation, time-frequency analysis, and data visualization to characterize evoked dynamics.

RESULTS

Each subject showed localization of a source for primary auditory evoked responses in the region of the auditory cortex, usually at a 20-30 ms latency. However, responses at 40-70 ms latency that also decreased following the second stimulus of a pair were not localizable to the auditory cortex, rather showing multiple sources usually including the frontal lobes.

CONCLUSIONS

The M50 response, which shows habituation to repetitive stimulation, was not localized to the auditory cortex, but showed multiple sources including frontal lobes.

SIGNIFICANCE

These MEG results suggest that sources for the M50 response may represent non-auditory, perhaps arousal-related, diffuse projections to the cortex.

The role of ultraviolet wavelengths in the mate-choice decisions of female three-spined sticklebacks

Female three-spined sticklebacks have been found to use visual cues when responding sexually towards courting males, often preferring more intensely red-coloured males, and males with blue rather than silver irises. However,traditionally the literature has failed to test preference across the full spectral range to which females might be sensitive, limiting analysis to the human-visible wavelengths of the electromagnetic spectrum. We studied the effects that the addition of ultraviolet wavelengths has on the mate-choice preferences of female sticklebacks using a two-choice paradigm. We found that females preferred males that were viewed across the full spectrum to males whose display lacked an ultraviolet component. Using suitable controls we were able to establish that female preference was sexually motivated and was not caused by a general preference for the manipulated light conditions. Our results indicate that female preference may be due to an enhancement in visual contrast when males are viewed in full spectrum conditions.

Human variability in xenobiotic metabolism and pathway-related uncertainty factors for chemical risk assessment: a review

This review provides an account of recent developments arising from a database that defined human variability in phase I metabolism (CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, hydrolysis, alcohol dehydrogenase), phase II metabolism (N-acetyltransferases, glucuronidation, glycine conjugation, sulphation) and renal excretion. This database was used to derive pathway-related uncertainty factors for chemical risk assessment that allow for human variability in toxicokinetics. Probe substrates for each pathway of elimination were selected on the basis that oral absorption was >95% and that the metabolic route was the primary route of elimination of the compound (60-100% of a dose). Intravenous data were used for compounds for which absorption was variable. Human variability in kinetics was quantified for each compound from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups of the population using parameters relating to chronic exposure (metabolic and total clearances, area under the plasma concentration-time curve (AUC)) and acute exposure (Cmax) (data not presented here). The pathway-related uncertainty factors were calculated to cover 95%, 97.5% and 99% of the population of healthy adults and of each subgroup. Pathway-related uncertainty factors allow metabolism data to be incorporated into the derivation of health-based guidance values. They constitute an intermediate approach between the general kinetic default factors (3.16) and a chemical-specific adjustment factor. Applications of pathway-related uncertainty factors for chemical risk assessment and future refinements of the approach are discussed. A knowledge-based framework to predict human variability in kinetics for xenobiotics showing a threshold dose below which toxic effects are not observed, is proposed to move away from default assumptions.

Human variability for metabolic pathways with limited data (CYP2A6, CYP2C9, CYP2E1, ADH, esterases, glycine and sulphate conjugation)

Human variability in the kinetics of a number of phase I (CYP2A6, CYP2C9, CYP2E1, alcohol dehydrogenase and hydrolysis) and phase II enzymes (glycine and sulphate conjugation) was analysed using probe substrates metabolised extensively (>60%) by these routes. Published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and available data on subgroups of the population (effects of ethnicity, age and disease) were abstracted using parameters relating primarily to chronic exposure [metabolic and total clearances, area under the plasma concentration time-curve (AUC)] and acute exposure (C(max)). Interindividual differences in kinetics for all these pathways were low in healthy adults ranging from 21 to 34%. Pathway-related uncertainty factors to cover the 95th, 97.5th and 99th centiles of healthy adults were derived for each metabolic route and were all below the 3.16 kinetic default uncertainty factor in healthy adults, with the possible exception of CYP2C9*3/*3 poor metabolisers (based on a very limited number of subjects). Previous analyses of other pathways have shown that neonates represent the most susceptible subgroup and this was true also for glycine conjugation for which an uncertainty factor of 29 would be required to cover 99% of this subgroup. Neonatal data were not available for any other pathway analysed.

Species-specific uncertainty factors for compounds eliminated principally by renal excretion in humans

An uncertainty factor of 100 is used to derive health-based guidance values for human intakes of chemicals based on data from studies in animals. The 100-fold factor comprises 10-fold factors for species differences and for interindividual differences in response. Each 10-fold factor can be subdivided into toxicokinetic and toxicodynamic aspects with a 4.0-fold factor to allow for kinetic differences between test species and humans. The current work determined the extent of interspecies differences in the internal dose (toxicokinetics) of compounds which are eliminated primarily by renal excretion in humans. An analysis of the published data showed that renal excretion was also the main route of elimination in the test species for most of the identified probe substrates. Interspecies differences were apparent for both the mechanism of renal excretion (glomerular filtration, tubular secretion and/or reabsorption) and the extent of plasma protein binding, both of which may affect renal clearance and therefore the magnitude of species differences in the internal dose. For compounds which are eliminated unchanged by both humans and the test species, the average differences in the internal doses between humans and animals were 1.6 for dogs, 3.3 for rabbits, 5.2 for rats and 13 for mice. This suggests that for renal excretion, the differences between humans and the rat and especially the mouse may exceed the 4.0-fold default factor for toxicokinetics.

Human variability in the renal elimination of foreign compounds and renal excretion-related uncertainty factors for risk assessment

Renal excretion is an important route of elimination for xenobiotics and three processes determine the renal clearance of a compound [glomerular filtration (about 120 ml/min), active renal tubular secretion (>120 ml/min) and passive reabsorption (<120 ml/min)]. Human variability in kinetics has been quantified using a database of 15 compounds excreted extensively by the kidney (>60% of a dose) to develop renal-excretion related uncertainty factors for the risk assessment of environmental contaminants handled via this route. Data were analysed from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating primarily to chronic exposure [renal and total clearances, area under the plasma concentration time-curve (AUC)] and acute exposure (Cmax). Interindividual variability in kinetics was low for both routes of exposure, with coefficients of variation of 21% (oral) and 24% (intravenous) that were largely independent of the renal processes involved. Renal-excretion related uncertainty factors were below the default kinetic uncertainty factor of 3.16 for most subgroups analysed with the exception of the elderly (oral data) and neonates (intravenous data) for whom renal excretion-related factors of 4.2 and 3.2 would be required to cover up to 99% of these subgroups respectively.

Polymorphic CYP2C19 and N-acetylation: human variability in kinetics and pathway-related uncertainty factors

CYP2C19-mediated oxidation and N-acetylation constitute major phase I and phase II polymorphic pathways of xenobiotic metabolism in humans. Analysis of human variability in kinetics for these pathways has been carried out for compounds metabolised extensively (>60%) by these routes. Data for minor substrates for CYP2C19 metabolism (10-60%) have also been analysed. Published pharmacokinetic studies (after oral and intravenous dosing) in CYP2C19 non-phenotyped healthy adults (NPs), and phenotyped extensive (EMs), slow-extensive (SEMs) and poor metabolisers (PMs) have been analysed using data for parameters that relate primarily to chronic exposure (metabolic and total clearances, area under the plasma concentration-time curve) and primarily to acute exposure (peak concentration). Similar analyses were performed for the N-acetylation pathway using data for fast acetylators (FA) and slow acetylators (SA). Interindividual variability in the kinetics of CYP2C19 substrates after oral dosage was greater in EMs than in NPs (60 vs 43% for clearances and 54 vs 45% for Cmax). Lower variability was found for N-acetylation for both phenotypes (32 and 22% for FA and SA, respectively). The internal dose of CYP2C19 substrates in PM subjects would be 31-fold higher than in EMs, while for N-acetylated substrates there was a three-fold difference between SA and FA subjects. Pathway-related uncertainty factors were above the default safety factor of 3.16 for most subgroups and values of 52 and 5.2 would be necessary to cover to the 99th centile of the poor metaboliser phenotype for CYP2C19 and N-acetylation, respectively. An exponential relationship (R(2)=0.86) was found between the extent of CYP2C19 metabolism and the difference in internal dose between EMs and PMs. The kinetic default factor (3.16) would cover PMs for substrates for which CYP2C19 was responsible for up to 20-30% of the metabolism in EMs.

Human variability in CYP3A4 metabolism and CYP3A4-related uncertainty factors for risk assessment

CYP3A4 constitutes the major liver cytochrome P450 isoenzyme and is responsible for the oxidation of more than 50% of all known drugs. Human variability in kinetics for this pathway has been quantified using a database of 15 compounds metabolised extensively (>60%) by this CYP isoform in order to develop CYP3A4-related uncertainty factors for the risk assessment of environmental contaminants handled via this route. Data were analysed from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating primarily to chronic exposure [metabolic and total clearances, area under the plasma concentration-time curve (AUC)] and acute exposure (Cmax). Interindividual variability in kinetics was greater for the oral route (46%, 12 compounds) than for the intravenous route (32%, 14 compounds). The physiological and molecular basis for the difference between these two routes of exposure is discussed. In relation to the uncertainty factors used for risk assessment, the default kinetic factor of 3.16 would be adequate for adults, whereas a CYP3A4-related factor of 12 would be required to cover up to 99% of neonates, which have lower CYP3A4 activity.

Human variability in polymorphic CYP2D6 metabolism: is the kinetic default uncertainty factor adequate?

Human variability in the kinetics of CYP2D6 substrates has been quantified using a database of compounds metabolised extensively (>60%) by this polymorphic enzyme. Published pharmacokinetic studies (after oral and intravenous dosing) in non-phenotyped healthy adults, and phenotyped extensive (EMs), intermediate or slow-extensive (SEMs) and poor metabolisers (PMs) have been analysed using data for parameters that relate primarily to chronic exposure (metabolic and total clearances, area under the plasma concentration time-curve) and primarily to acute exposure (peak concentration). Similar analyses were performed with the available data for subgroups of the population (age, ethnicity and disease). Interindividual differences in kinetics for markers of oral exposure were large for non-phenotyped individuals and for EMs (coefficients of variation were 67-71% for clearances and 54-63% for C(max)), whereas the intravenous data indicated a lower variability (34-38%). Comparisons between EMs, SEMs and PMs revealed an increase in oral internal dose for SEMs and PMs (ratio compared to EMs=3 and 9-12, respectively) associated with lower variability than that for non-phenotyped individuals (coefficients of variation were 32-38% and 30% for SEMs and PMs, respectively). In relation to the uncertainty factors used for risk assessment, most subgroups would not be covered by the kinetic default of 3.16. CYP2D6-related factors necessary to cover 95-99% of each subpopulation ranged from 2.7 to 4.1 in non-phenotyped healthy adults and EMs to 15-18 in PMs and 22-45 in children. An exponential relationship (R(2)=0.8) was found between the extent of CYP2D6 metabolism and the uncertainty factors. The extent of CYP2D6 involvement in the metabolism of a substrate is critical in the estimation of the CYP2D6-related factor. The 3.16 kinetic default factor would cover PMs for substrates for which CYP2D6 was responsible for up to 25% of the metabolism in EMs.

Spaceflight induces changes in the synaptic circuitry of the postnatal developing neocortex

The establishment of the adult pattern of neocortical circuitry depends on various intrinsic and extrinsic factors, whose modification during development can lead to alterations in cortical organization and function. We report the effect of 16 days of spaceflight [Neurolab mission; from postnatal day 14 (P14) to P30] on the neocortical representation of the hindlimb synaptic circuitry in rats. As a result, we show, for the first time, that development in microgravity leads to changes in the number and morphology of cortical synapses in a laminar-specific manner. In the layers II/III and Va, the synaptic cross-sectional lengths were significantly larger in flight animals than in ground control animals. Flight animals also showed significantly lower synaptic densities in layers II/III, IV and Va. The greatest difference was found in layer II/III, where there was a difference of 344 million synapses per mm(3) (15.6% decrease). Furthermore, after a 4 month period of re-adaptation to terrestrial gravity, some changes disappeared (i.e. the alterations were transient), while conversely, some new differences also appeared. For example, significant differences in synaptic density in layers II/III and Va after re-adaptation were no longer observed, whereas in layer IV the density of synapses increased notably in flight animals (a difference of 185 million synapses per mm(3) or 13.4%). In addition, all the changes observed only affected asymmetrical synapses, which are known to be excitatory. These results indicates that terrestrial gravity is a necessary environmental parameter for normal cortical synaptogenesis. These findings are fundamental in planning future long-term spaceflights.

Mathematical modelling and quantitative methods

The present review reports on the mathematical methods and statistical techniques presently available for hazard characterisation. The state of the art of mathematical modelling and quantitative methods used currently for regulatory decision-making in Europe and additional potential methods for risk assessment of chemicals in food and diet are described. Existing practices of JECFA, FDA, EPA, etc., are examined for their similarities and differences. A framework is established for the development of new and improved quantitative methodologies. Areas for refinement, improvement and increase of efficiency of each method are identified in a gap analysis. Based on this critical evaluation, needs for future research are defined. It is concluded from our work that mathematical modelling of the dose-response relationship would improve the risk assessment process. An adequate characterisation of the dose-response relationship by mathematical modelling clearly requires the use of a sufficient number of dose groups to achieve a range of different response levels. This need not necessarily lead to an increase in the total number of animals in the study if an appropriate design is used. Chemical-specific data relating to the mode or mechanism of action and/or the toxicokinetics of the chemical should be used for dose-response characterisation whenever possible. It is concluded that a single method of hazard characterisation would not be suitable for all kinds of risk assessments, and that a range of different approaches is necessary so that the method used is the most appropriate for the data available and for the risk characterisation issue. Future refinements to dose-response characterisation should incorporate more clearly the extent of uncertainty and variability in the resulting output.

Human variability in glucuronidation in relation to uncertainty factors for risk assessment

The appropriateness of the default uncertainty factor for human variability in kinetics has been investigated for glucuronidation using an extensive database of substrates metabolised primarily by this pathway. Inter-individual variability was quantified for 15 compounds from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating to chronic exposure (metabolic and total clearances, area under the plasma concentration time-curve (AUC)) and acute exposure (C(max)). Low inter-individual variability (about 30-35%) was found for all parameters (clearance corrected or not corrected for body weight, metabolic clearance, oral AUC and C(max)) after either iv or oral administration to healthy adults. The overall variability of 31% for glucuronidation in healthy adults supported the validity of the default kinetic uncertainty factor of 3.16 for this group, because it would cover more than 99% of individuals. Comparisons between potentially sensitive subgroups and healthy adults using differences in means and variability indicated that neonates showed the greatest impairment of glucuronidation, and that the 3.16 kinetic default factor applied to the mean data for adults would be inadequate for this subpopulation. The in vivo data have been used to derive pathway-related default factors for compounds eliminated largely via glucuronidation.

Uncertainty factors for chemical risk assessment: interspecies differences in glucuronidation

For the risk assessment of effects other than cancer, a safe daily intake in humans is generally derived from a surrogate threshold dose (e.g. NOAEL) in an animal species to which an uncertainty factor of 100 is usually applied. This 100-fold is to allow for possible interspecies (10-fold) and interindividual (10-fold) differences in response to a toxicant, and incorporates toxicodynamic and toxicokinetic aspects of variability. The current study determined the magnitude of the interspecies differences in the internal dose of compounds for which glucuronidation is the major pathway of metabolism in either humans or in the test species. The results showed that there are major interspecies differences in the nature of the biological processes which influence the internal dose, including the route of metabolism, the extent of presystemic metabolism and enterohepatic recirculation. The work presented does not support the refinement of the interspecies toxicokinetic default to species- and pathway-specific values, but demonstrates the necessity for risk assessments to be carried out using quantitative chemical-specific data which define the fundamental processes which will influence the internal dose of a chemical (toxicokinetics), or the interaction of toxicant with its target site (toxicodynamics).

Smoking and mental illness

Patients with mental illness have a higher incidence of smoking than the general population and are the major consumers of tobacco products. This population includes subjects with schizophrenia, manic depression, depression, posttraumatic stress disorder (PTSD), attention-deficit disorder (ADD), and several other less common diseases. Smoking cessation treatment in this group of patients is difficult, often leading to profound depression. Several recent findings suggest that increased smoking in the mentally ill may have an underlying biological etiology. The mental illness schizophrenia has been most thoroughly studied in this regard. Nicotine administration normalizes several sensory-processing deficits seen in this disease. Animal models of sensory deficits have been used to identify specific nicotinic receptor subunits that are involved in these brain pathways, indicating that the alpha 7 nicotinic receptor subunit may play a role. Genetic linkage in schizophrenic families also supports a role for the alpha 7 subunit with linkage at the alpha 7 locus on chromosome 15. Bipolar disorder has some phenotypes in common with schizophrenia and also exhibits genetic linkage to the alpha 7 locus, suggesting that these two disorders may share a gene defect. The alpha 7 receptor is decreased in expression in schizophrenia. [(3)H]-Nicotine binding studies in postmortem brain indicate that high-affinity nicotinic receptors may also be affected in schizophrenia.

Uncertainty factors for chemical risk assessment. human variability in the pharmacokinetics of CYP1A2 probe substrates

A 100-fold uncertainty factor is used to derive acceptable daily intakes for compounds causing thresholded toxicity. The 10-fold factor for human variability can be further subdivided into two factors of 10(0.5) (3.16) to allow for toxicokinetics and toxicodynamics. The validity of the human kinetic subfactor has been analysed in relation to CYP1A2 metabolism using published in vivo pharmacokinetic parameters selected to reflect chronic exposure (metabolic and total clearances and area under the plasma concentration-time curve: CLm, CL and AUC) and acute exposure (the peak plasma concentration, C(max)). The variability in CYP1A2 activity in healthy adults, based on data after oral and intravenous dosage (CLm, CL and AUC), ranged from 34 to 42%. The variability in C(max) was 21%. The default kinetic factor of 3.16 would cover at least 99% of the healthy adult population, assuming that the data were log-normally distributed, but would give lower protection for some subgroups (pregnant women at term, healthy elderly, patients with liver disease), and was inadequate for neonates. This analysis of in vivo kinetic data for CYP1A2 substrates illustrates the importance of quantifying human variability in specific metabolic pathways, and of identifying potentially susceptible subgroups of the human population, in order to determine the scientific validity of uncertainty factors.

Uncertainty factors for chemical risk assessment: interspecies differences in the in vivo pharmacokinetics and metabolism of human CYP1A2 substrates

The 100-fold default uncertainty factor is used to convert a no-observed-adverse-effect level (NOAEL) from a animal toxicity study, to a "safe" value for human intake. The composite uncertainty factor (100) has to allow for interspecies (10-fold) and interindividual (10-fold) differences in toxicokinetics and toxicodynamics. The aim of the current study was to assess the validity of the interspecies default for toxicokinetics (4.0) for each of the test species (dog, rabbit, rat and mouse), using published data for compounds eliminated by CYP1A2 in humans (caffeine, theobromine, theophylline and paraxanthine). An analysis of the published literature showed that the absorption, bioavailability and route of excretion were generally similar between humans and the test species, for each probe substrate. However, interspecies differences in the route of metabolism, and the enzymes involved in this process, were identified. The magnitude of difference in the internal dose, between species, showed that values for the mouse (10.6) and rat (5.4) exceed the 4.0-fold default, whereas the rabbit (2.6) and dog (1.6) were below this value. This work supports the need to replace the generic default factors by a compound-related value derived from specific, relevant, quantitative data; this would result in more relevant and reliable non-cancer risk assessments.

Fate of the mushroom hydrazine agaritine in the rat and mouse

The fate of the mushroom hydrazine [14C]agaritine was investigated in the mouse and rat strains previously employed in carcinogenicity studies with the edible mushroom Agaricus bisporus. Agaritine was rapidly absorbed in both species, achieving higher blood levels in the mouse, but with similar area under the curve. Covalent binding of agaritine material to proteins was detected only in the liver and kidney, but the extent of binding was the same in the rat and mouse. Most of the radioactivity was excreted during the first 24 hours in both animal species: in the rat it was distributed equally between urine and feces, whereas in the mouse more of the radioactivity was excreted in the urine. No qualitative differences in the metabolic profile were evident, but quantitative differences were observed. Treatment of the urine with deconjugating enzymes did not reveal the presence of any conjugates. Agaritine, N'-acetyl-4-(hydroxymethyl)phenylhydrazine, and 4-(hydroxymethyl)benzene diazonium ion were not detected in the urine or in the plasma of either species. No mutagens or promutagens were detected by the Ames mutagenicity assay in the urine of either species after exposure to agaritine. Repeated administration of agaritine to rats and mice did not alter the urinary metabolic profile and excretion of radioactivity. Similarly, feeding mice a raw mushroom diet, according to the protocol employed in the carcinogenicity studies, did not modulate the excretion of radioactivity or the urinary metabolic pattern. No major species differences in the fate of agaritine in rat and mouse were noted that could provide a rationale for the carcinogenicity of A. bisporus in the mouse, but not in the rat.

The use of surrogate endpoints to assess potential toxicity in humans

Data on toxic effects in humans may come from epidemiology studies, accidental poisonings, surveillance schemes or following intentional exposures. In many cases, a surrogate endpoint related to the adverse effect is investigated. Effects produced following intentional exposures are usually restricted to readily reversible, mild surrogate endpoints of the adverse effect of concern. Not all initial interactions within the target organ are related to the toxic effect, and many measurements are biomarkers of exposure not response. Biomarkers of response represent surrogate endpoints of response only if they are critical to the mode of action. The use of biomarkers and the possible problems with using surrogate endpoints are illustrated with data on aniline, cadmium, carbon monoxide, erythrosine, paracetamol (acetaminophen) and styrene. In vivo surrogate endpoints are normally used in risk assessment directly, whereas in vitro surrogate endpoints can be incorporated by the development of a biologically based dose-response model, or used to replace a default uncertainty factor by a chemical-specific adjustment factor.

The metabolism and bioactivation of agaritine and of other mushroom hydrazines by whole mushroom homogenate and by mushroom tyrosinase

Whole homogenates of Agaricus bisporus metabolised the mushroom hydrazine agaritine [beta-N-(gamma-L(+)glutamyl)-4-(hydroxymethyl) phenylhydrazine] to generate at least three metabolites. None of these metabolites, however, was the free hydrazine [4-(hydroxymethyl)phenylhydrazine], the postulated metabolite of agaritine believed to be formed as a result of the loss of the gamma-glutamyl group, the reaction being catalysed by gamma-glutamyltransferase. The three metabolites of agaritine displayed weak mutagenic activity towards Salmonella typhimurium strain TA104. 4-(Hydroxymethyl)phenylhydrazine, as the N'-acetyl derivative, was metabolised by mushroom tyrosinase to yield a number of metabolites that induced a mutagenic response in S. typhimurium TA104. Similar to N'-acetyl-4-(hydroxymethyl)phenylhydrazine, agaritine was extensively metabolised by the mushroom tyrosinase but, in contrast, the structurally related N'-acetyl-4-hydrazinobenzoic acid did not serve as substrate of this enzyme, implying a critical role for the hydroxymethyl group at the para-position. In conclusion, the current studies have demonstrated for the first time that: (a) whole mushroom homogenates readily metabolise agaritine but not to the postulated 4-(hydroxymethyl)phenylhydrazine; and (b) mushroom tyrosinase metabolises agaritine and N'-acetyl-4-(hydroxymethyl)phenylhydrazine, in the latter case forming genotoxic metabolites.

An analysis of the need for an additional uncertainty factor for infants and children

Uncertainty factors have been used for over 40 years to establish safe intakes of threshold toxicants. Tenfold factors are used to allow for species differences and for human variability, with extra factors for database inadequacies. The proposal to introduce an additional 10-fold factor for pesticides when exposure of infants and children is anticipated implies either age-related differences between species or differences within humans which exceed those present in adults. Alternatively, the extra factor could be related to deficiencies of current testing methods or concerns over irreversibility in developing organ systems. Available data do not provide a scientific rationale for the extra factor due to inadequacy of inter- and intraspecies uncertainty factors. Justification for the factor therefore must relate to the adequacy and sensitivity of current methods or concern about irreversible effects in the developing organism.

Bioactivation of the carcinogen 11-methoxy-16, 17-dihydro-15H-cyclopenta[a]phenanthrene

The title compound is a more potent carcinogen than would be anticipated from its simple phenanthrene structure lacking further D-ring conjugation. In vitro it undergoes microsomal metabolism to yield as major metabolites its 15- and 17-alcohols and its 16, 17-diol; other minor metabolites are also derived from attack at the 5-membered ring, but no evidence of aromatic oxidation is apparent. The title compound is a weak mutagen in the Ames' test with Salmonella typhimurium TA100, but only with microsomal bio-activation. The 17-ol and 16,17-diol are inactive, with or without biological activation. By contrast the 15-alcohol, a rather reactive compound, is a strong mutagen both in the presence and absence of the bio-activation system. This, therefore, may be the proximate carcinogen, and its structural analogy to the naturally occurring hepato-carcinogen safrole is noted.

The application of in vitro data in the derivation of the acceptable daily intake of food additives

The acceptable daily intake (ADI) for food additives is commonly derived from the NOAEL (no-observed-adverse-effect level) in long-term animal in vivo studies. To derive an ADI a safety or uncertainty factor (commonly 100) is applied to the NOAEL in the most sensitive test species. The 100-fold safety factor is considered to be the product of both species and inter-individual differences in toxicokinetics and toxicodynamics. Although in vitro data have previously been considered during the risk assessment of food additives, they have generally had no direct influence on the calculation of ADI values. In this review 18 food additives are evaluated for the availability of in vitro toxicity data which might be used for the derivation of a specific data-derived uncertainty factor. For the majority of the food additives reviewed, additional in vitro tests have been conducted which supplement and support the short- and long-term in vivo toxicity studies. However, it was recognized that these in vitro studies could not be used in isolation to derive an ADI; only when sufficient in vivo mechanistic data are available can such information be used in a regulatory context. Additional short-term studies are proposed for the food additives which, if conducted, would provide data that could then be used for the calculation of data-derived uncertainty factors.