Longitudinal analysis of the effect of water hardness on atopic eczema: evidence for gene-environment interaction.

BACKGROUND: Several studies have identified an association between water hardness and atopic eczema (AE); however, there is a paucity of longitudinal data in early life. OBJECTIVES: To examine whether water hardness is associated with an increased risk of AE and skin barrier dysfunction in infants and to assess effect modification by filaggrin (FLG) loss-of-function variants. METHODS: We performed a longitudinal analysis of data from infants in the Enquiring About Tolerance (EAT) study, who were enrolled at 3 months and followed up until 36 months of age. RESULTS: Of 1303 infants enrolled in the EAT study, 91·3% (n = 1189) attended the final clinic visit and 94·0% (n = 1225) of participants' families completed the 36-month questionnaire. In total, 761 (58·4%) developed AE by 36 months. There was no overall association between exposure to harder (> 257 mg L-1 CaCO3 ) vs. softer (≤ 257 mg L-1 CaCO3 ) water: adjusted hazard ratio (HR) 1·07, 95% confidence interval (CI) 0·92-1·24. However, there was an increased incidence of AE in infants with FLG mutations exposed to hard water (adjusted HR 2·72, 95% CI 2·03-3·66), and statistically significant interactions between hard water plus FLG and both risk of AE (HR 1·80, 95% CI 1·17-2·78) and transepidermal water loss (0·0081 g m-2 h-1 per mg L-1 CaCO3 , 95% CI 0·00028-0·016). CONCLUSIONS: There is evidence of an interaction between water hardness and FLG mutations in the development of infantile AE.

The role of skin and gut microbiota in the development of atopic eczema.

Conventional culture-based studies have suggested that a reduction in microbial exposure in early life predisposes to atopic eczema and allergies. However, molecular microbiological methods have shown that conventional culture fails to grow around 80% of the bacterial flora. More recent work reviewed in this paper has employed next generation sequencing to study the influence of the gut and skin microbiota, both with regard to the risk of developing atopic eczema but also the role of pathogenic and commensal bacteria in established disease. Birth cohorts investigating the gastrointestinal tract reported reduced faecal microbiota diversity among those who later developed atopic eczema, using gel electrophoresis, real-time PCR or 16S ribosomal RNA gene pyrosequencing. However, the inverse association with reduced faecal bacterial diversity was not confirmed in cross-sectional studies among patients with established atopic eczema. Only two studies investigated the cutaneous microbiota in a longitudinal study design and both were unable to provide evidence that Staphylococcus aureus colonisation precedes the development of atopic eczema. Next generation sequencing has confirmed the cross-sectional association between atopic eczema and S. aureus colonisation. The two studies that used this approach have also shown that disease flares are associated with a significant fall in skin microbiota diversity and an increase in the relative abundance of both S. aureus and epidermidis. Interestingly, S. aureus elimination does not appear to be the main reason why atopic eczema improves after a flare and antimicrobial and anti-inflammatory therapy enhances bacterial diversity. Further, well-phenotyped birth cohorts that take key confounders, such as antibiotic exposure, into account are required.

Patients' ability to treat anaphylaxis using adrenaline autoinjectors: a randomized controlled trial.

BACKGROUND: Previous work has shown patients commonly misuse adrenaline autoinjectors (AAI). It is unclear whether this is due to inadequate training, or poor device design. We undertook a prospective randomized controlled trial to evaluate ability to administer adrenaline using different AAI devices. METHODS: We allocated mothers of food-allergic children prescribed an AAI for the first time to Anapen or EpiPen using a computer-generated randomization list, with optimal training according to manufacturer's instructions. After one year, participants were randomly allocated a new device (EpiPen, Anapen, new EpiPen, JEXT or Auvi-Q), without device-specific training. We assessed ability to deliver adrenaline using their AAI in a simulated anaphylaxis scenario six weeks and one year after initial training, and following device switch. Primary outcome was successful adrenaline administration at six weeks, assessed by an independent expert. Secondary outcomes were success at one year, success after switching device, and adverse events. RESULTS: We randomized 158 participants. At six weeks, 30 of 71 (42%) participants allocated to Anapen and 31 of 73 (43%) participants allocated to EpiPen were successful - RR 1.00 (95% CI 0.68-1.46). Success rates at one year were also similar, but digital injection was more common at one year with EpiPen (8/59, 14%) than Anapen (0/51, 0%, P = 0.007). When switched to a new device without specific training, success rates were higher with Auvi-Q (26/28, 93%) than other devices (39/80, 49%; P < 0.001). CONCLUSIONS: AAI device design is a major determinant of successful adrenaline administration. Success rates were low with several devices, but were high using the audio-prompt device Auvi-Q.

Assessing the efficacy of oral immunotherapy for the desensitisation of peanut allergy in children (STOP II): a phase 2 randomised controlled trial: a critical appraisal.

AIM: Anagnostou et al. investigated the efficacy of oral immunotherapy (OIT) in treating peanut allergy. SETTING AND DESIGN: An unmasked randomized controlled crossover trial of 7-16 year olds with double-blind placebo-controlled food challenge (DBPCFC)-proven peanut allergy. The first phase compared an active group undergoing 26 weeks of OIT with daily ingestion of peanut protein vs. a control group avoiding peanuts. Both groups underwent DBPCFC to peanut at 26 weeks. In the second phase the control group was then offered OIT for 26 weeks. STUDY EXPOSURE: Participants undergoing OIT attended hospital every 2 weeks to initiate and increase their daily peanut protein dose through nine stages (2, 5, 12·5, 25, 50, 100, 200, 400 and 800 mg - about five peanuts), subsequently maintaining consumption at the highest tolerated dose. Primary outcome The primary outcome compared the proportions of active- and control-group participants able to ingest a cumulative dose of 1400 mg of peanut protein (about 10 peanuts) during their DBPCFC at the end of the first phase without reacting. Secondary outcomes Further outcomes included the proportion of participants who tolerated the top maintenance dosage of 800 mg protein up to 26 weeks; the proportion of the control group who were desensitized or tolerated daily ingestion of 800 mg protein in the second phase; threshold changes in no observed adverse effect level after OIT (NOAEL: defined as the highest dose of peanut protein tolerated in milligrams of protein during challenge or immunotherapy); change in quality of life; number and type of adverse events; and immunological parameters (basophil reactivity, peanut-specific IgE, total IgE and skin-prick test). RESULTS: Primary outcome Twenty-four of 39 (62%) of the active group were able to tolerate the 1400 mg of peanut protein during their DBPCFC after 26 weeks of OIT, compared with none of the 46 control participants (P < 0·001). Secondary outcomes Twenty-five of 46 (54%) of the control group had a negative 1400-mg peanut protein challenge at the end of phase 2. Combining the two groups, 49 of 85 children (58%) were desensitized. Thirty-three of 39 (85%) active participants in phase one and 42 of 46 (91%) control participants in phase two tolerated 800 mg of OIT daily - a combined result of 75 of 85 (88%) trial participants. The median absolute change in NOAEL between baseline and 26 weeks was 1345 mg (P = 0·002), or a 25·5-fold increase (P < 0·001) for the active group. Both the active and control groups demonstrated a significant improvement (decrease) in Food Allergy Quality of Life scores after OIT in the under-13-year-old participants: -1·61 and -1·41, respectively (both P < 0·001). Mild side-effects predominated, with 54 (57%) reporting abdominal pain and 31 (33%) reporting vomiting. However, 21 (22%) also reported wheezing and one (1%) laryngeal oedema. One participant received adrenaline by self-administration on two occasions for wheezing. CONCLUSIONS: Anagnostou et al. concluded that OIT successfully induced desensitization in challenge-proven peanut-allergic children and resulted in a clinically and socially meaningful increase in tolerated peanut protein. Quality of life improved after intervention and there was a good safety profile.

Variables influencing the toxic response to organophosphates in humans.

Concerns and doubts associated with the predictable health effects in humans following exposure to xenobiotics is primarily due to the failure to consider the variables influencing the toxic response in each instance. Lack of correlation between laboratory data, animal experiments and clinical findings in man associated with exposure to organophosphates (OPs) is an example. We have reviewed the literature to identify the variables that need to be considered following exposure to OPs. These include factors related to the OP (physico-chemical properties, solvents, impurities), duration and routes of exposure, and factors related to the individual(s) exposed. Individual variables include variations in metabolic, sequestration and excretory processes and health status (age, gender, environmental factors, concurrent medications, cholinergic status). The assessment of ill-health following exposure is critical to the development and compliance with guidelines and to the adoption of the best instrumentation. We have suggested a schematic assessment that needs to be applied for each exposure associated with organophosphates and provided the reasons for the development of this format. Exposure to xenobiotics through the environment, occupation or following therapy is an unavoidable aspect of modern life. Application of the principles discussed to each xenobiotic exposure is necessary to provide accurate and adequate information to advance the prevention or minimising toxicity.

The health significance of pesticide variability in individual commodity items.

The observed phenomenon of variability of residues in individual fruit and vegetables has a number of implications for risk assessment. The main implication is that the possibility of acute toxic effects in humans has to be considered, where items are commonly consumed unprocessed, are commonly consumed at a single sitting and the pesticide involved has substantial acute toxicity. The main groups of pesticides of concern are the anticholinesterase organophosphates and carbamates. The problem partly arises from the fact that, with some older pesticides, studies of the type most appropriate for setting acute reference doses (ARfDs) have not been carried out. As a result ARfDs are based on studies of length that is greater than ideal. While there is little evidence from the scientific or medical literature that food-borne pesticide poisoning is occurring on any major scale, the symptomatology of such poisoning would be non-specific and the pattern in the population, sporadic. Hence it is likely that pesticide-related illness, through food, would be missed. It is concluded that risk assessments should be improved, using refined safety factors, more appropriate studies and better intake data. The reasons for the variability could be sought and remedied or the application conditions of the pesticide modified.

An in vitro and an in vivo unscheduled DNA synthesis assay with a zinc oxide/hexachloroethane (Zn/HCE) smoke.

1. Since Zn/HCE smoke has been shown previously to be weakly positive in the Ames test, and negative in the bone marrow micronucleus assay, other assays including a second in vivo assay examining unscheduled DNA synthesis (UDS) in rat hepatocytes has been carried out, as recommended by the UK Department of Health guidelines. 2. Zn/HCE smoke was assessed for its ability to induce DNA repair in an UDS assay both in vitro in cultured rat hepatocytes and in rat hepatocytes after in vivo treatment by inhalation. 3. For the in vitro investigation, two studies were carried out assessing media exposed to Zn/HCE smoke using at least seven concentrations up to a toxic level. At the highest concentration of Zn/HCE smoke, where some viable cells were seen, an increase in UDS was observed in both experiments. However this was not statistically significant, was only seen at a level where toxicity was observed and was therefore considered not to be biologically significant. 4. In the in vivo investigation, one study was carried out in three separate parts, assessing two doses of Zn/HCE smoke characterised by their zinc content as approximately 20 and 56 micrograms l-1 air. A dose-related increase in UDS was observed which was not statistically significant. The positive control behaved as anticipated, showing a highly statistically significant response. 5. It was concluded that Zn/HCE smoke did not induce unscheduled DNA repair in the in vitro or in vivo UDS assays under the conditions used in the studies. The overall lack of genotoxic effect of this smoke in this and previous studies in this laboratory would not suggest a major health hazard.

Organophosphate poisoning.

The present review discusses the structure of the anticholinesterase organophosphates (OPs), which are used predominantly as insecticides. OP poisoning can occur in a variety of situations and can be accidental or suicidal. It is common in developing countries. The cholinergic syndrome is caused by acetylcholinesterase inhibition, and diagnosis is based on the clinical signs and symptoms as well as the measurement of inhibition of erythrocyte acetylcholinesterase and/or plasma cholinesterase activity. Antidotal treatment is with atropine, an enzyme reactivator such as pralidoxime and diazepam. Anticholinesterase OPs may produce effects other than the acute cholinergic syndrome, including the intermediate syndrome. Later effects may include organophosphorus-induced delayed neuropathy. Certain OPs are exploited for their anticholinesterase effects, including defoliants such as 'DEF', herbicides such as glyphosate, fire retardants and industrial intermediates. The toxicology of this group is heterogeneous and they may or may not possess anticholinesterase activity.

Studies of the pharmacokinetics and metabolism of 4-amino-propiophenone (PAPP) in rats, dogs and cynomolgus monkeys.

The pharmacokinetics and metabolism of 4-aminopropiophenone (PAPP), a cyanide antidote, have been studied in rats, dogs and cynomolgus monkeys using 14C-PAPP. Radiolabelled material was rapidly excreted in all three species, mainly in urine. In rats, PAPP was metabolized by N-acetylation, while in dogs, ring and aliphatic hydroxylation occurred. In monkeys, both N-acetylation and oxidation took place. In the latter pathway, PAPP was oxidized to p-aminobenzoic acid which underwent amino acid-conjugation to p-aminohippuric acid. In rat blood in vitro, the PAPP metabolites, p-aminobenzoic, p-aminohippuric and N-acetyl-p-aminobenzoic acid were only weak methaemoglobin producers.

The formation of methaemoglobin by 4-aminopropiophenone (PAPP) and 4-(N-hydroxy) aminopropiophenone.

Oral dosing of rats with the cyanide antidote 4-aminopropiophenone (PAPP), brought about peak methaemoglobin levels at 15-40 min, but peak levels were attained at at 15-25 min after intravenous dosing. After both oral and intravenous administration at equimolar doses, 4-(N-hydroxy)aminopropiophenone (PHAPP), the putative methaemoglobin-producing metabolite of PAPP, produced higher peak levels of methaemoglobin than PAPP. Plasma from rats injected with PAPP was capable of forming methaemoglobin when added to naive rat erythrocytes. The identity of the metabolite responsible is discussed.

Effects of experimental sarin intoxication on the morphology of the mouse diaphragm: a light and electron microscopical study.

A sublethal dose of sarin (GB, isopropyl methylphosphonofluoridate) was administered to mice. The animals were killed up to 28 days after dosing. Following excision, diaphragms were divided into two halves and used for ultrastructural examination and light microscopy. Planar sections of diaphragm showed muscle fibre degeneration and predominantly mononuclear infiltration, notably at 24 h. Semithin toluidine blue-stained sections and ultrastructural studies demonstrated hypercontraction with gross disruption of sarcomeres including loss of Z and A bands, which appeared to be associated with neuromuscular junctions. All changes were rapidly regressing by 7 days.

Neurotoxicity of 1-methoxycycloheptatriene--a Purkinje cell toxicant.

The toxicity of 1-methoxycycloheptatriene (1-MCHT), a sensory irritant, has been investigated in beagles. It was found to produce gross inco-ordination of the limbs at intravenous doses greater than 10 mg kg-1. The main histological abnormalities were in the cerebellum and consisted of Purkinje cell death and subsequent reactive gliosis. A few necrotic neurons were seen in the diencephalon, pons and medulla. Haematological abnormalities, e.g. leucocytosis with relative lymphopenia, were seen, while biochemical changes included hyperglycaemia and a rise in plasma aminotransferases. The no-effect dose for the histological and biochemical changes was the same. These abnormalities are compared with cerebellar changes observed in acrylamide and other toxic states.

Studies on the mutagenicity of a zinc oxide-hexachloroethane smoke.

1. A suitable method has been developed for generating atmospheres of zinc oxide/hexachloroethane smoke (ZnHCE). 2. The smoke was investigated using the Ames test and the micronucleus assay. 3. It was weakly mutagenic to the bacteria, but in the bone marrow no increases in micronuclei were detected up to toxic levels of the smoke. 4. The method used here could be applied to other pyrotechnic mixtures which give rise to complex mixtures of products.

A histochemical study of changes observed in the mouse diaphragm after organophosphate poisoning.

A sublethal dose of sarin (GB, isopropyl methylphosphonofluoridate) was administered to mice. The animals were killed up to 28 d after dosing and frozen sections were made of the excised diaphragms which were stained using haematoxylin and eosin and a modified Gomori trichrome method. Muscle fibre degeneration and mononuclear infiltration were seen, notably at 24 h and 3 d. A number of histochemical procedures were carried out, including the GBHA procedure for ionized calcium. Calcium accumulation, seen at 4 h, was the earliest abnormality observed. All changes were rapidly regressing by 5 d and histological appearances were normal by 14 d. It was concluded that sarin produced myopathic changes preceded by calcium accumulation.

Evaluation of the efficacy of dimercapto chelating agents for the treatment of systemic organic arsenic poisoning in rabbits.

1 The standard drug for the treatment of arsenic poisoning is BAL (dimercaprol). BAL possesses marked side-effects and a low safety ratio, drawbacks which new BAL analogues, DMPS and DMSA, do not possess. 2 The efficacy of three chelating agents, BAL, DMPS and DMSA, has been evaluated as a treatment for systemic organic arsenic poisoning, induced by intravenous dichloro(2-chlorovinyl)arsine (lewisite) administration to rabbits. Equimolar dosing schedules were used based upon realistic doses for the most toxic agent, BAL. 3 It was concluded that all three dimercapto chelating agents provided significant protection against the lethal systemic effects of lewisite, and, under the test conditions reported here, there was no significant difference between them in therapeutic efficacy. 4 The cause of mortality following intravenous lewisite in treated and untreated rabbits was pulmonary damage. 5 It is considered that DMPS and DMSA are worthy of further study as replacements for BAL in the treatment of systemic poisoning by lewisite.

Histochemical demonstration of calcium accumulation in muscle fibres after experimental organophosphate poisoning.

The LD50 of subcutaneously-injected sarin (GB: isopropyl methylphosphonofluoridate) in mice was 172 micrograms kg-1. Mice were treated with sarin at doses between 25 and 150 micrograms kg-1, administered subcutaneously. After sacrifice of the animals, the diaphragms were removed and stained for acetylcholinesterase activity and the presence of ionized calcium. Calcium was found in the diaphragms of those mice to which sarin had been administered at doses of 50 micrograms kg-1 or above. Calcium accumulation was not present in diaphragms from those animals that had received 25 micrograms kg-1. Calcium accumulation occurred earliest and remained longest in diaphragms from those animals receiving the highest doses. Accumulation of calcium was associated with end-plates, as demonstrated by an acetylcholinesterase histochemical method.