Adiponectin, leptin and insulin in breast milk: associations with maternal characteristics and infant body composition in the first year of life.

BACKGROUND/OBJECTIVES: Breastfeeding may protect against excessive weight gain during infancy. However, the breast milk components responsible for this effect are unknown. We examined the variation of three breast milk hormones (adiponectin, leptin and insulin) according to maternal characteristics and determined their association with infant body composition. SUBJECTS/METHODS: We studied a representative subset of 430 breastfed infants in the CHILD birth cohort. Breast milk was collected at 4 months postpartum and hormone concentrations were measured using the MesoScale Discovery System. Weight-for-length (WFL) and body mass index (BMI) z-scores were calculated according to the World Health Organization reference standard from infant anthropometrics measured at 4 months and 1 year. Maternal BMI and demographics were self-reported. RESULTS: Breast milk hormone concentrations varied widely between mothers. The geometric mean (range) was 19.4 (3.7-74.4) ngml-1 for adiponectin; 361 (31-3968) pgml-1 for leptin; and 589 (53-5557) pgml-1 for insulin. Maternal BMI was positively correlated with breast milk insulin (r=+0.40, P<0.0001) and leptin (r=+0.71, P<0.0001), but not adiponectin (r=-0.02, P=0.68). Breast milk hormone concentrations were also associated with maternal ethnicity, parity and breastfeeding exclusivity at sample collection. Independent of these factors and maternal diabetes, smoking and breastfeeding duration, higher breast milk leptin was associated with lower infant WFL z-score at 4 months (ß -0.67, 95% confidence interval (CI): -1.17, -0.17 for highest vs lowest quintile) and 1 year (ß -0.58, 95% CI: -1.02, -0.14). Insulin showed a U-shaped association, with intermediate concentrations predicting the lowest infant WFL z-score at 4 months (ß -0.51, 95% CI: -0.87, -0.15 for third vs lowest quintile) and 1 year (ß -0.35, 95% CI: -0.66, -0.04). Similar results were seen with infant BMI. Breast milk adiponectin was not significantly associated with infant body composition. CONCLUSIONS: Breast milk hormone concentrations were associated with several fixed and modifiable maternal characteristics. Higher concentrations of leptin and intermediate concentrations of insulin were associated with lower infant WFL in the first year of life.

Patterns of allergic sensitization and atopic dermatitis from 1 to 3 years: Effects on allergic diseases.

BACKGROUND: While allergic sensitization and atopic dermatitis (AD) are known to increase the risk for allergic diseases, the impact of different temporal and clinical patterns of sensitization and AD is less well defined. OBJECTIVE: We investigated patterns of sensitization and AD from early infancy to age 3, and the differential risk of developing allergic diseases within each pattern in a general cohort. METHODS: Children (n = 2629) from the Canadian Healthy Infant Longitudinal Development (CHILD) Study underwent skin prick tests and were assessed clinically for AD at ages 1 and 3 years. We applied an unsupervised latent class analysis (LCA) to the following 5 factors at these ages: AD, food sensitization, inhalant sensitization, poly-sensitization to foods and poly-sensitization to inhalants. The risks for developing asthma, allergic rhinitis and food allergy at 3 years were evaluated for each identified group. RESULTS: Five distinct classes were revealed by LCA: healthy (81.8%), atopic dermatitis (7.6%), inhalant sensitization (3.5%), transient sensitization (4.1%) and persistent sensitization (3.2%). Using healthy children as the baseline, children in the "atopic dermatitis" group had the next lowest risk for all allergic outcomes at 3 years; those in the "inhalant sensitization" group had the highest risk for allergic rhinitis; children in the "transient sensitization" group were at an increased risk for food allergy; while children in the "persistent sensitization" group had the highest risk for all allergic diseases. CONCLUSION AND CLINICAL RELEVANCE: There is substantial heterogeneity among allergen-sensitized children. Researchers and clinicians need to be aware of the non-specificity associated with labelling children simply as "atopic" and "non-atopic" without considering the timing of their atopic history, type of sensitization and AD status. Children with AD who were poly-sensitized to foods at an early age appear to be at greatest risk of developing other allergic diseases.

Stability of pro- and anti-inflammatory immune biomarkers for human cohort studies.

BACKGROUND: Although discovery research has identified the importance of dozens of pro- and anti-inflammatory immune mediators in the pathogenesis, maintenance, exacerbation and resolution of inflammatory diseases, most human cohort studies have incorporated few or no immunological intermediate phenotypes in their analyses. Significant hindrances have been (1) the limited panel of biomarkers known to be readily detected in healthy human populations and (2) the stability, hence utility, of such biomarkers to repeated analysis. METHODS: The frequency and stability of 14 plasma biomarkers linked to in vivo immune regulation of allergic and autoimmune inflammatory disorders was determined in 140 healthy pediatric and adult participants. The impact of initial and multiple subsequent freeze/thaw cycles on pro-inflammatory (CCL2, CXCL10, IL-18, TNFα, IL-6), anti-inflammatory (IL-10, sTNF-RII, IL-1Ra), acute phase proteins (CRP, PTX3) and other biomarkers (sST2, IL-1RAcP) was subsequently quantified. RESULTS: Multiple biomarkers capable of providing an innate immune signature of inflammation were readily detected directly ex vivo in healthy individuals. These biomarker levels were unaffected when comparing paired data sets from freshly obtained, never frozen plasma or serum and matched aliquots despite extensive freeze/thaw cycles. Neither age nor sex affected stability. Similarly, no quantitative differences were found following repetitive analysis of inflammatory biomarkers in culture samples obtained following in vitro stimulation with TLR and RLR ligands. CONCLUSIONS: A broad panel of in vivo and ex vivo cytokine, chemokine and acute phase protein biomarkers that have been linked to human chronic inflammatory disorders are readily detected in vivo and remain stable for analysis despite multiple freeze thaw cycles. These data provide the foundation and confidence for large scale analyses of panels of inflammatory biomarkers to provide better understanding of immunological mechanisms underlying health versus disease.

Impact of maternal intrapartum antibiotics, method of birth and breastfeeding on gut microbiota during the first year of life: a prospective cohort study.

OBJECTIVE: Dysbiosis of the infant gut microbiota may have long-term health consequences. This study aimed to determine the impact of maternal intrapartum antibiotic prophylaxis (IAP) on infant gut microbiota, and to explore whether breastfeeding modifies these effects. DESIGN: Prospective pregnancy cohort of Canadian infants born in 2010-2012: the Canadian Healthy Infant Longitudinal Development (CHILD) Study. SETTING: General community. SAMPLE: Representative sub-sample of 198 healthy term infants from the CHILD Study. METHODS: Maternal IAP exposures and birth method were documented from hospital records and breastfeeding was reported by mothers. Infant gut microbiota was characterised by Illumina 16S rRNA sequencing of faecal samples at 3 and 12 months. MAIN OUTCOME MEASURES: Infant gut microbiota profiles. RESULTS: In this cohort, 21% of mothers received IAP for Group B Streptococcus prophylaxis or pre-labour rupture of membranes; another 23% received IAP for elective or emergency caesarean section (CS). Infant gut microbiota community structures at 3 months differed significantly with all IAP exposures, and differences persisted to 12 months for infants delivered by emergency CS. Taxon-specific composition also differed, with the genera Bacteroides and Parabacteroides under-represented, and Enterococcus and Clostridium over-represented at 3 months following maternal IAP. Microbiota differences were especially evident following IAP with emergency CS, with some changes (increased Clostridiales and decreased Bacteroidaceae) persisting to 12 months, particularly among non-breastfed infants. CONCLUSIONS: Intrapartum antibiotics in caesarean and vaginal delivery are associated with infant gut microbiota dysbiosis, and breastfeeding modifies some of these effects. Further research is warranted to explore the health consequences of these associations. TWEETABLE ABSTRACT: Maternal #antibiotics during childbirth alter the infant gut #microbiome.

Infant gut microbiota and food sensitization: associations in the first year of life.

BACKGROUND: The gut microbiota is established during infancy and plays a fundamental role in shaping host immunity. Colonization patterns may influence the development of atopic disease, but existing evidence is limited and conflicting. OBJECTIVE: To explore associations of infant gut microbiota and food sensitization. METHODS: Food sensitization at 1 year was determined by skin prick testing in 166 infants from the population-based Canadian Healthy Infant Longitudinal Development (CHILD) study. Faecal samples were collected at 3 and 12 months, and microbiota was characterized by Illumina 16S rRNA sequencing. RESULTS: Twelve infants (7.2%) were sensitized to ≥ 1 common food allergen at 1 year. Enterobacteriaceae were overrepresented and Bacteroidaceae were underrepresented in the gut microbiota of food-sensitized infants at 3 months and 1 year, whereas lower microbiota richness was evident only at 3 months. Each quartile increase in richness at 3 months was associated with a 55% reduction in risk for food sensitization by 1 year (adjusted odds ratio 0.45, 95% confidence interval 0.23-0.87). Independently, each quartile increase in Enterobacteriaceae/Bacteroidaceae ratio was associated with a twofold increase in risk (2.02, 1.07-3.80). These associations were upheld in a sensitivity analysis among infants who were vaginally delivered, exclusively breastfed and unexposed to antibiotics. At 1 year, the Enterobacteriaceae/Bacteroidaceae ratio remained elevated among sensitized infants, who also tended to have decreased abundance of Ruminococcaceae. CONCLUSIONS AND CLINICAL RELEVANCE: Low gut microbiota richness and an elevated Enterobacteriaceae/Bacteroidaceae ratio in early infancy are associated with subsequent food sensitization, suggesting that early gut colonization may contribute to the development of atopic disease, including food allergy.

The Canadian healthy infant longitudinal development birth cohort study: biological samples and biobanking.

BACKGROUND: It is hypothesised that complex interactions between genetic and environmental factors give rise to allergy and asthma in childhood. The Canadian Healthy Infant Longitudinal Development (CHILD) study was designed to explore these factors. METHODS: CHILD is a longitudinal, general population birth cohort study following infants from mid-pregnancy to age 5 years. Over this time period, biological samples, questionnaires, clinical measures and environmental data are collected. RESULTS: A total of 3624 families have been recruited, and many thousands of samples and questionnaires have been collected, annotated, and archived. This report outlines the rationale and methodology for collecting and storing diverse biological samples from parents and children in this study, and the mechanisms for their release for analyses. CONCLUSIONS: The CHILD sample and data repository is a tremendous current and future resource and will provide a wealth of information not only informing studies of asthma and allergy, but also potentially in many other aspects of health relevant for Canadian infants and children.

Infant antibiotic exposure and the development of childhood overweight and central adiposity.

BACKGROUND: Obesity has been associated with disruption of the gut microbiota, which is established during infancy and vulnerable to disruption by antibiotics. OBJECTIVES: To investigate the association between early-life antibiotic exposure and subsequent development of overweight and central adiposity. METHODS: Provincial health-care records were linked to clinical and survey data from a Canadian longitudinal birth cohort study. Antibiotic exposure during the first year of life was documented from prescription records. Overweight and central adiposity were determined from anthropometric measurements at ages 9 (n=616) and 12 (n=431). Associations were determined by multiple logistic regression. RESULTS: Infants receiving antibiotics in the first year of life were more likely to be overweight later in childhood compared with those who were unexposed (32.4 versus 18.2% at age 12, P=0.002). Following adjustment for birth weight, breastfeeding, maternal overweight and other potential confounders, this association persisted in boys (aOR 5.35, 95% confidence interval (CI) 1.94-14.72) but not in girls (aOR 1.13, CI 0.46-2.81). Similar gender-specific associations were found for overweight at age 9 (aOR 2.19, CI 1.06-4.54 for boys; aOR 1.20, CI 0.53-2.70 for girls) and for high central adiposity at age 12 (aOR 2.85, CI 1.24-6.51 for boys; aOR 1.59, CI 0.68-3.68 for girls). CONCLUSIONS: Among boys, antibiotic exposure during the first year of life was associated with an increased risk of overweight and central adiposity in preadolescence, indicating that antibiotic stewardship is particularly important during infancy. Given the current epidemic of childhood obesity and the high prevalence of infant antibiotic exposure, further studies are necessary to determine the mechanisms underlying this association, to identify the long-term health consequences, and to develop strategies for mitigating these effects when antibiotic exposure cannot be avoided.

Associations between bacterial communities of house dust and infant gut.

The human gut is host to a diverse and abundant community of bacteria that influence health and disease susceptibility. This community develops in infancy, and its composition is strongly influenced by environmental factors, notably perinatal anthropogenic exposures such as delivery mode (Cesarean vs. vaginal) and feeding method (breast vs. formula); however, the built environment as a possible source of exposure has not been considered. Here we report on a preliminary investigation of the associations between bacteria in house dust and the nascent fecal microbiota from 20 subjects from the Canadian Healthy Infant Longitudinal Development (CHILD) Study using high-throughput sequence analysis of portions of the 16S rRNA gene. Despite significant differences between the dust and fecal microbiota revealed by Nonmetric Multidimensional Scaling (NMDS) analysis, permutation analysis confirmed that 14 bacterial OTUs representing the classes Actinobacteria (3), Bacilli (3), Clostridia (6) and Gammaproteobacteria (2) co-occurred at a significantly higher frequency in matched dust-stool pairs than in randomly permuted pairs, indicating an association between these dust and stool communities. These associations could indicate a role for the indoor environment in shaping the nascent gut microbiota, but future studies will be needed to confirm that our findings do not solely reflect a reverse pathway. Although pet ownership was strongly associated with the presence of certain genera in the dust for dogs (Agrococcus, Carnobacterium, Exiguobacterium, Herbaspirillum, Leifsonia and Neisseria) and cats (Escherichia), no clear patterns were observed in the NMDS-resolved stool community profiles as a function of pet ownership.

Combined exposure to dog and indoor pollution: incident asthma in a high-risk birth cohort.

The impact of single exposures on asthma development is better understood than the effect of multiple exposures. The objective of the present study was to evaluate the effect of combined early exposure to dog allergen (Can-f1) plus indoor nitrogen dioxide (NO2) or environmental tobacco smoke (ETS) on asthma and bronchial hyperreactivity (BHR) in a high-risk birth cohort. We also aimed to assess atopy's impact on the effects of these exposures. Peri-birth ETS exposure was measured using cord blood cotinine (CCot). During year 1, atopy, NO2, Can-f1, and urinary cotinine (UCot) were measured. At 7 yrs of age, 380 children were assessed for asthma and BHR. Exposure effects were determined using stepwise multiple linear regression. Co-exposure to elevated Can-f1 and NO2, or Can-f1 and ETS (CCot), increased risk for asthma, relative to having neither such exposure (OR 4.8 (95% CI 1.1-21.5) and 2.7 (1.1-7.1), respectively); similar risks resulted when substituting dog ownership for allergen. Atopy increased asthma and BHR risk associated with several exposures; notably, atopy with elevated UCot, relative to atopy without such exposure, increased risk of BHR (OR 3.1 (95% CI 1.1-8.6)). In a high-risk birth cohort, early co-exposure to Can-f1 and NO2 or ETS increased the risk of incident asthma. Atopy increased the risk of asthma and BHR associated with ETS.

Fast food consumption counters the protective effect of breastfeeding on asthma in children?

BACKGROUND: Fast food consumption and childhood asthma have rapidly increased in recent decades. During the same period there has been an increased rate of prolonged breastfeeding. OBJECTIVE: To evaluate if fast food consumption was associated with asthma in children, and if the proposed protective effect of breastfeeding on asthma was altered by fast food consumption. METHODS: This case-control study included 246 children with allergist-diagnosed asthma and 477 non-asthmatic controls at age 8-10 years. Information on fast food consumption and exclusive breastfeeding was obtained from questionnaire data. The association between asthma and fast food consumption was evaluated. Asthma in relation to exclusive breastfeeding was also evaluated, taking into account fast food consumption as a modifying factor. RESULTS: Children with asthma were more likely to consume fast food than children without asthma [crude odds ratio (OR) 1.70, 95% confidence interval (CI) 1.23-2.34]. In comparison to prolonged exclusive breastfeeding (> or =12 weeks), asthma was positively associated with short-term exclusive breastfeeding (<12 weeks) in children who never or occasionally consumed fast food (crude OR 1.84, 95% CI 1.09-3.11), but not in children who frequently consumed fast food (crude OR 1.07, 95% CI 0.72-1.61). The P-value for this interaction (0.109) was borderline. Children with high fast food consumption who were exclusively breastfed <12 weeks as infants, had greater than a twofold risk of asthma compared with infants who had been exclusively breastfed for a longer time period and who did not become high consumers of fast food in later childhood. These findings were not affected after final adjustment of confounders and covariates. CONCLUSION: Fast food consumption is associated with asthma in children and potentially counteracts the protective effect of prolonged breastfeeding on asthma. This may explain the paradoxical phenomenon of parallel increased rates of prolonged breastfeeding and asthma in children. 556-561.

A novel study design to investigate the early-life origins of asthma in children (SAGE study).

This is a description of the Study of Asthma, Genes and the Environment (SAGE), a novel birth cohort created from provincial healthcare administrative records. It is a general population-based cohort, composed of children at high and low risk for asthma, living in urban and rural environments in Manitoba, Canada. The SAGE study captures the complete longitudinal healthcare records of children born in 1995 and contains detailed information on early-life exposures, such as antibiotic utilization and immunization, in relationship to the development of asthma. Nested within the birth cohort is a case-control study, which was created to collect information on home environmental exposures from detailed surveys and home dust sampling, to confirm asthma status in children and use this data to validate healthcare database measures of asthma, to determine differences in immune system responsiveness to innate and adaptive immune stimuli in asthma, to genotype children for genes likely associated with the development of asthma and to study the epigenetic regulation of pre-established protective vs allergic immune responses. The SAGE study is a multidisciplinary collaboration of researchers from pediatric allergy, population health, immunology, and genetic and environmental epidemiology. As such, it serves as a fertile, interdisciplinary training ground for graduate students, and postdoctoral and clinician fellows.

Histamine is an intracellular messenger mediating platelet aggregation.

Inhibition of human platelet aggregation by N,N-diethyl-2-[4-(phenylmethyl)phenoxy]ethanamine-HCl (DPPE), a novel antagonist of histamine binding, suggested that histamine might serve a critical role in cell function. Phorbol-12-myristate-13-acetate (PMA) or collagen was found to increase platelet histamine content in parallel with promotion of aggregation. Inhibitors of histidine decarboxylase (HDC) suppressed both aggregation and the elevation of histamine content, whereas DPPE inhibited aggregation only. In saponin-permeabilized platelets, added histamine reversed the inhibition by DPPE or HDC inhibitors on aggregation induced by PMA or collagen. The results indicate a role for histamine as an intracellular messenger, which in platelets promotes aggregation.

Impact of maternal pre-pregnancy overweight on infant overweight at 1 year of age: associations and sex-specific differences.

BACKGROUND: Maternal overweight or obesity (OWOB) is linked to gestational diabetes, fetal macrosomia and higher rates of caesarean delivery. OBJECTIVES: The study aims to assess whether maternal pre-pregnancy OWOB is associated with infant overweight in a sex-dependent manner, independent of microbiota-altering variables. METHODS: Weight and length measurements of 955 mother-infant pairs were obtained from the Canadian Healthy Infant Longitudinal Development cohort. Maternal pre-pregnancy weight was defined as follows: normal, overweight (25 ≤ body mass index < 30) and obese (body mass index ≥ 30). Age and sex-adjusted weight-for-length z-scores >97th percentile were classified as infant overweight at age 1 year. Associations between pre-pregnancy and infant overweight were determined by linear and logistic regression, adjusting for covariates. RESULTS: Maternal pre-pregnancy OWOB were associated with infant weight-for-length and overweight risk at 1 year. Except for pre-pregnancy obesity, these associations were not attenuated appreciably after adjustment for birth mode, exclusivity of breastfeeding, exposure to antibiotics and infant sex. Yet only boys born to mothers with obesity were three times more likely to become overweight at age 1 independent of microbiota-altering variables. Pre-pregnancy obesity was associated with weight-for-length in male and female infants. CONCLUSIONS: Maternal pre-pregnancy OWOB increases the risk of infant overweight, and this association is more evident in male infants.

Infant gut immunity: a preliminary study of IgA associations with breastfeeding.

Secretory immunoglobulin A (IgA) plays a critical role in gut mucosal immune defense. Initially provided by breastmilk, IgA production by the infant gut is gradually stimulated by developing gut microbiota. This study reports associations between infant fecal IgA concentrations 4 months after birth, breastfeeding status and other pre/postnatal exposures in 47 infants in the Canadian Healthy Infant Longitudinal Development cohort. Breastfed infants and first-born infants had higher median fecal IgA concentrations (23.11 v. 9.34 µg/g protein, P<0.01 and 22.19 v. 8.23 µg/g protein, P=0.04). IgA levels increased successively with exclusivity of breastfeeding (ß-coefficient, 0.37, P<0.05). This statistical association was independent of maternal parity and household pets. In the absence of breastfeeding, female sex and pet exposure elevated fecal IgA to levels found in breastfed infants. In addition to breastfeeding, infant fecal IgA associations with pre/postnatal exposures may affect gut immunity and risk of allergic disease.

Effects of rhIL-11 on normal dogs and after sublethal radiation.

The effects of recombinant human interleukin-11 (rhIL-11) were studied in normal dogs and dogs given otherwise sublethal total-body irradiation (TBI) without marrow transplantation. Ten normal dogs were given rhIL-11 subcutaneously, twice daily for 14 days at varying doses, two dogs at 30 micrograms/kg/day, four dogs at 60 micrograms/kg/day, two dogs at 120 micrograms/kg/day, and two dogs at 240 micrograms/kg/day. Peripheral blood platelet counts increased in all dogs. The increase in platelet counts ranged from 1.4 to 3.1 times the pre-treatment level. The greater increases of platelets were associated with higher doses (p = 0.01). No change in platelet size was evident except at the dose of 240 micrograms/kg/day. There were no changes in the total white blood cell (WBC) count or differential. A higher proportion of megakaryocytes with a DNA content of 32N/64N was observed in dogs treated with rhIL-11 at day 7 (n = 6) than for control dogs that did not receive rhIL-11 (n = 7; p = 0.01). In both peripheral blood and marrow, significantly increased hematopoietic progenitors (i.e, colony-forming unit granulocyte/macrophage [CFU-GM]) were present 7 and 14 days after the start of treatment. Concentrations of serum fibrinogen increased by a median of 155 mg/dL at day 7 of rhIL-11 (p < 0.01). Cholesterol also increased by a median of 52 mg/dL at day 14 (p < 0.01). There was a single death of a non-irradiated dog from pneumonitis on day 15 after the start of rhIL-11 administration at a dose of 120 micrograms/kg/day. All other non-irradiated dogs tolerated rhIL-11 without any significant adverse effects. Five dogs were given 200 cGy TBI without marrow grafting, followed by 240 micrograms/kg/day rhIL-11 subcutaneously in two divided doses for 28 days starting within 2 hours of TBI. The results in this group were compared with 10 dogs that had previously or concurrently been given 200 cGy without marrow grafting or hematopoietic growth factors. Two of the five treatment dogs died of pneumonitis on day 13 compared to one death among 10 control dogs on day 24. Among dogs that survived to hematologic recovery, the rhIL-11 dogs had decreased platelet counts (< 150,000) for a median of 24 days (range = 24 to 41) compared to a median of 28 days (range = 21-40) for the control group. Treatment with rhIL-11 increased platelet counts, platelet size, ploidy number of megakaryocytes, and marrow and peripheral blood CFU-GM in normal dogs.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential binding properties of protein A and protein G for dog immunoglobulins.

We studied the binding of dog immunoglobulins G, A, M and E to protein A and protein G. Passive cutaneous anaphylaxis (PCA) testing was used for the measurement of dog IgE and enzyme-linked immunosorbent assays (ELISA) were used for the measurements of dog IgG, IgA and IgM. Protein A from lyophilized cells of Staphylococcus aureus bound 97% of IgE, 98% of IgG, 81% of IgA, and 97% of IgM. Protein A-Sepharose CL-4B bound 87% of IgE, 100% of IgG and IgA, and 98% of IgM. In a stepwise elution with varying pH, a small amount of IgE was eluted at pH 5 and pH 6 and all the remaining Igs were eluted at pH 3 from the protein A column. In contrast to protein A, dog IgE was not bound to Protein G-Sepharose, while 100% of IgG, 95% of IgA, and 44% of IgM were bound to Protein G-Sepharose.

Biochemical and ultrastructural studies suggest that the effects of thapsigargin on human platelets are mediated by changes in intracellular calcium but not by intracellular histamine.

The involvement of intracellular histamine in thapsigargin (Tg)-induced platelet aggregation was studied. Platelet aggregation induced by 0.25 and 0.5 microM Tg was not accompanied by a rise in intracellular histamine but a significant (p < 0.01) increase in the level of intracellular histamine was observed at 1 microM Tg. Preincubation of platelets with inhibitors of histamine metabolizing enzymes had little effect on intracellular histamine levels in platelets stimulated by 0.5 microM Tg. In addition, the inhibitors of histidine decarboxylase (HDC), alpha-methyl histidine (alpha-MH) and alpha-fluoromethyl histidine (alpha-FMH) failed to inhibit Tg-induced aggregation. The intracellular histamine receptor antagonist, N,N-diethyl-2-[4-(phenylmethyl)phenoxy] ethanamine. HCl (DPPE), inhibited Tg-induced aggregation but with IC50 values dependent on the concentration of agonist used. The inhibitory effects of DPPE on Tg-induced aggregation were not reversed by the addition of histamine to saponin-permeabilized platelets suggesting non-histamine mediated effects of DPPE on Tg-induced aggregation. Tg stimulated an increase in the cytosolic free calcium concentration which was unaffected by DPPE indicating that the effects of DPPE are also not due to the inhibition of mobilization of cytosolic calcium. The ultrastructural studies suggest that the major Tg-induced changes (pseudopod formation and granule centralization) are consistent with a primary role for Tg to mobilize calcium; DPPE had very little effect on these ultrastructural changes. The results indicate that the effects of Tg on human platelets are mediated by an increase in cytosolic calcium but not by intracellular histamine.

Christmas candy maker's asthma. IgG4-mediated pectin allergy.

We evaluated a 29-year-old candy maker with no history of asthma who developed asthma after exposure to pectin, a compound manufactured from fruits and fruit rinds. Following eight years of employment during which he added pectin to a recipe for Christmas candies, the candymaker developed acute respiratory symptoms. Challenge testing with the pectin mixture caused a 40 percent decrease in FEV1. Skin prick testing was positive to the pectin extract. Total IgE was normal and pectin-specific IgE antibodies were not detected. A strongly positive pectin-specific IgG4 antibody response was present that was not detected in a control serum and could be inhibited by the addition of pectin. Antigen-specific IgG4 should be sought in IgE negative cases of occupational asthma.

Trends in physician-diagnosed asthma prevalence in Manitoba between 1980 and 1990.

We attempted to assess recent changes in the prevalence of physician-diagnosed asthma and the possible influence of diagnostic exchange on these trends. The routinely collected data of the provincial Health Insurance Plan (physicians' claims) were used to determine the annual prevalence of physician-diagnosed asthma in Manitoba. Results indicate that the prevalence of physician-diagnosed asthma increased for all age groups in both male and female subjects between 1980 and 1990. The average increases were the highest in the age group 5 to 14 years for both sexes. The average increases varied with age and there were significant differences between the two sexes. There was evidence of increasing diagnostic exchange, that is, a tendency to label patients with asthma instead of alternative diagnoses. This was particularly prominent in those younger than 35 years of age. However, the increased prevalence of physician-diagnosed asthma, even for the younger population, cannot be fully explained by diagnostic exchange.