Kinetics and thermodynamics of BI-BII interconversion altered by T:G mismatches in DNA.

T:G mismatches in DNA result in humans primarily from deamination of methylated CpG sites. They are repaired by redundant systems, such as thymine DNA glycosylase (TDG) and methyl-binding domain enzyme (MBD4), and maintenance of these sites has been implicated in epigenetic processes. The process by which these enzymes identify a canonical DNA base in the incorrect basepairing context remains a mystery. However, the conserved contacts of the repair enzymes with the DNA backbone suggests a role for protein-phosphate interaction in the recognition and repair processes. We have used 31P NMR to investigate the energetics of DNA backbone BI-BII interconversion, and for this work have focused on alterations to the activation barriers to interconversion and the effect of a mismatch compared with canonical DNA. We have found that alterations to the ΔG of interconversion for T:G basepairs are remarkably similar to U:G basepairs in the form of stepwise differences in ΔG of 1-2 kcal/mol greater than equivalent steps in unmodified DNA, suggesting a universality of this result for TDG substrates. Likewise, we see perturbations to the free energy (∼1 kcal/mol) and enthalpy (2-5 kcal/mol) of activation for the BI-BII interconversion localized to the phosphates flanking the mismatch. Overall our results strongly suggest that the perturbed backbone energetics in T:G basepairs play a significant role in the recognition process of DNA repair enzymes.

Prenatal antimicrobial use and early-childhood body mass index.

BACKGROUND/OBJECTIVES: Growing evidence suggests that antibiotic use is associated with childhood body mass index (BMI), potentially via mechanisms mediated by gut microbiome alterations. Less is known on the potential role of prenatal antimicrobial use in offspring obesity risk. We examined whether prenatal antibiotic or antifungal use was associated with BMI at the age of 2 years in 527 birth cohort participants. METHODS/SUBJECTS: Antimicrobial use was obtained from the prenatal medical record. Height and weight were measured at the age of 2 years. Overweight/obesity was defined as a BMI ⩾85th percentile. RESULTS: A total of 303 (57.5%) women used antibiotics and 101 (19.2%) used antifungals during pregnancy. Prenatal antifungal use was not associated with child BMI at the age of 2 years. In the fully adjusted model, prenatal antibiotic use was associated with a 0.20±0.10 (P=0.046) higher mean BMI Z-score at the age of 2 years. Associations between prenatal antibiotic use and childhood BMI varied by trimester of exposure, with first or second-trimester exposure more strongly associated with larger BMI at the age of 2 years for both BMI Z-score (interaction P=0.032) and overweight/obesity (interaction P=0.098) after covariate adjustment. CONCLUSIONS: Prenatal antibiotic, but not antifungal, use is associated with larger BMI at the age of 2 years; associations were stronger for antibiotic exposures in earlier trimesters. Future studies examining whether these associations are due to alterations in the maternal and/or infant microbiome are necessary. Children who are overweight at the age of 2 years are at higher risk for being overweight as they age; prenatal antibiotic use is a potentially modifiable exposure that could reduce childhood obesity.

Dog introduction alters the home dust microbiota.

Research has largely reported that dog exposure is associated with reduced allergic disease risk. Responsible mechanism(s) are not understood. The goal was to investigate whether introducing a dog into the home changes the home dust microbiota. Families without dogs or cats planning to adopt a dog and those who were not were recruited. Dust samples were collected from the homes at recruitment and 12 months later. Microbiota composition and taxa (V4 region of the 16S rRNA gene) were compared between homes that did and did not adopt a dog. A total of 91 dust samples from 54 families (27 each, dog and no dog; 17 dog and 20 no dog homes with paired samples) were analyzed. A significant dog effect was seen across time in both unweighted UniFrac and Canberra metrics (both P = .008), indicating dog introduction may result in rapid establishment of rarer and phylogenetically related taxa. A significant dog-time interaction was seen in both weighted UniFrac (P < .001) and Bray-Curtis (P = .002) metrics, suggesting that while there may not initially be large relative abundance shifts following dog introduction, differences can be seen within a year. Therefore, dog introduction into the home has both immediate effects and effects that emerge over time.

Subgroup differences in the associations between dog exposure during the first year of life and early life allergic outcomes.

BACKGROUND: The effect of dog exposure on the risk of children developing allergic disease remains controversial. Many analyses have not considered that associations may vary within population subgroups. OBJECTIVE: To examine whether associations between living with a dog in the first year of life and allergic outcomes vary within subgroups selected a priori (race, gender and delivery mode). METHODS: Black (n = 496) and White (n = 196) children enrolled in the WHEALS birth cohort study had a clinical examination at age 2 years to assess eczema and allergen-specific IgE (sIgE) and perform skin prick testing (SPT). Whether the child lived with an indoor dog in the first year of life was assessed through interview, as was doctor diagnosis of asthma at ages 3-6 years. RESULTS: Living with a dog was associated with decreased odds of having ≥ 1 positive SPT (OR = 0.56, 95% CI: 0.34, 0.91) and having eczema (OR = 0.34, 95% CI: 0.20, 0.60). The association with SPT was stronger in those children born via caesarean section (c-section) vs. vaginally (OR = 0.29, 95% CI: 0.12, 0.74 vs. OR = 0.76, 95% CI: 0.43, 1.37, respectively, interaction P = 0.087) and in those who were firstborn vs. not (OR = 0.27, 95% CI: 0.11, 0.67 vs. OR = 0.82, 95% CI: 0.45, 1.47, respectively, interaction P = 0.044). The association with eczema was stronger in children born vaginally compared with those born via caesarean section (OR = 0.17, 95% CI: 0.06, 0.43 vs. OR = 0.65, 95% CI: 0.31, 1.35, respectively, interaction P = 0.025) and was stronger in Black vs. White children (OR = 0.30, 95% CI: 0.15, 0.61 vs. OR = 0.78, 95% CI: 0.29, 2.11, respectively, interaction P = 0.12). Dog keeping was not significantly inversely associated with having ≥ 1 elevated sIgE and only approached statistical significance with asthma. CONCLUSIONS AND CLINICAL RELEVANCE: Results likely vary between studies due to variability of specific exposure-outcome associations in subgroups defined by other factors as well as the relative distributions of those subgroups. Important allergic disorder associations will be missed without subgroup analyses.

Combined effects of prenatal medication use and delivery type are associated with eczema at age 2 years.

BACKGROUND: Separately, prenatal antibiotics and Caesarian delivery have been found to be associated with increased risk of allergic diseases. It is not clear whether these factors may modify the effect of each other. OBJECTIVE: To assess whether the associations between delivery types and eczema, sensitization and total IgE at age 2 years were modified by maternal use of prenatal medications. METHODS: Prenatal charts of women enrolled in the WHEALS birth cohort were reviewed for delivery mode and medications prescribed and administered throughout their entire pregnancy, including systemic antibiotics and vaginally applied antifungal medications. The associations between the delivery mode and select medications and, eczema, sensitization (≥ 1 of 10 allergen-specific IgE ≥ 0.35 IU/mL) and total IgE at age 2 years were assessed. RESULTS: There was a lower risk of eczema among vaginally vs. c-section born children (relative risk adjusted for race = aRR = 0.77, 95% CI 0.56, 1.05). Although not statistically significantly different, this association was stronger among the subset of children born vaginally to a mother who did not use systemic antibiotics or vaginal antifungal medications (aRR = 0.69, 95% CI 0.44, 1.08) compared to those born vaginally to mothers who used systemic antibiotics or vaginal antifungals (aRR = 0.81, 95% CI 0.57, 1.14). A protective association between vaginal birth and sensitization (aRR = 0.86, 95% CI 0.72, 1.03) was similar for those children born vaginally to a mother who did not (aRR = 0.87, 95% CI 0.69, 1.10) and who did (RR = 0.85, 95% CI 0.70, 1.04) use systemic antibiotics or vaginal antifungal medications. There were no associations with total IgE. CONCLUSIONS: Children born vaginally had lower risk of eczema and sensitization compared with those born via c-section; however, the protective association with eczema may be slightly weakened when mothers took systemic antibiotics or vaginally applied medications during pregnancy.

Are cats and dogs the major source of endotoxin in homes?

UNLABELLED: Previous studies have suggested that exposure to cats and dogs during early childhood reduces the risk of allergic disease, possibly by increasing home endotoxin exposure. This study asked the question of whether cats and dogs are the dominant influence on dust endotoxin concentrations in homes after considering other variables reportedly associated with endotoxin. The presence of cats or dogs in homes, household and home characteristics, and dust endotoxin concentrations from 5 locations were assessed in 966 urban and suburban homes. Whether considered together as pets or as cats and dogs separately, the presence of cats and dogs significantly contributed to living room and bedroom floor endotoxin concentrations, but not to bed endotoxin concentrations. However, the two variables consistently related to endotoxin in all home sites were the home occupant density (occupants/room) and cleanliness of the home. Our data suggest that reducing occupant density and improving home cleanliness would reduce home endotoxin concentrations more than removing pet cats or dogs from the home. PRACTICAL IMPLICATIONS: Many studies have shown that early childhood exposure to indoor cats or dogs is associated with a reduced risk of later allergic disease and asthma. An important question is whether alteration in allergic risk associated with cat and dog exposure results from increased endotoxin exposure or from some other associated exposure. Our findings show that cats and dogs are not the dominant source of endotoxin in homes; rather, the density of human occupation and poor cleaning contribute more consistently to higher home endotoxin concentrations especially in the beds.

Racial disparities in allergic outcomes in African Americans emerge as early as age 2 years.

BACKGROUND: Racial disparities in allergic disease outcomes have been reported with African Americans suffering disproportionately compared to White individuals. OBJECTIVE: To examine whether or not racial disparities are present as early as age 2 years in a racially diverse birth cohort in the Detroit metropolitan area. METHODS: All children who were participants in a birth cohort study in the Detroit metropolitan area were invited for a standardized physician exam with skin prick testing and parental interview at age 2 years. Physicians made inquiries regarding wheezing and allergy symptoms and inspected for and graded any atopic dermatitis (AD). Skin testing was performed for Alternaria, cat, cockroach, dog, Dermatophagoides farinae (Der F), Short Ragweed, Timothy grass, egg, milk and peanut. Specific IgE was measured for these same allergens and total IgE was determined. RESULTS: African American children (n = 466) were more likely than White children (n = 223) to have experienced any of the outcomes examined: at least 1 positive skin prick test from the panel of 10 allergens (21.7% vs. 11.0%, P = 0.001); at least one specific IgE ≥ 0.35 IU/mL (out of a panel of 10 allergens) (54.0% vs. 42.9%, P = 0.02); had AD (27.0% vs. 13.5%, Chi-square P < 0.001); and to ever have wheezed (44.9% vs. 36.0%, P = 0.03). African American children also tended to have higher total IgE (geometric means 23.4 IU/mL (95%CI 20.8, 27.6) vs. 16.7 IU/mL (95%CI 13.6, 20.6 IU/mL), Wilcoxon Rank Sum P = 0.004). With the exception of wheezing, the associations did not vary after adjusting for common social economic status variables (e.g. household income), environmental variables (endotoxin; dog, cat and cockroach allergen in house dust) or variables that differed between the racial groups (e.g. breastfeeding). After adjustment, the wheeze difference was ameliorated. CONCLUSIONS: With disparities emerging as early as age 2 years, investigations into sources of the disparities should include the prenatal period and early life.

Lifetime dog and cat exposure and dog- and cat-specific sensitization at age 18 years.

BACKGROUND: Prior research about whether keeping a dog or cat at home causes allergies to that pet has been limited to outcomes in early childhood. OBJECTIVE: Evaluate the association between lifetime dog and cat exposure and allergic sensitization to the specific animal at 18 years of age. METHODS: Participants enrolled in the Detroit Childhood Allergy Study birth cohort during 1987-1989 were contacted at the age 18 years. Sensitization to dog or cat was defined as animal-specific IgE ≥ 0.35 kU/L. Annual interview data from childhood and follow-up interviews at age 18 years were used to determine lifetime indoor dog and cat exposure (indoor was defined when the animal spent >50% of their time inside the house). Exposure was considered in various ways: first year, age groups and cumulative lifetime. Analyses were conducted separately for dogs and cats. RESULTS: Among males, those with an indoor dog during the first year of life had half the risk [relative risk (RR)=0.50, 95% confidence interval (CI) 0.27, 0.92] of being sensitized to dogs at age 18 compared with those who did not have an indoor dog in the first year. This was also true for males and females born via c-section (RR=0.33, 95% CI 0.07, 0.97). Overall, teens with an indoor cat in the first year of life had a decreased risk (RR=0.52, 95% CI 0.31, 0.90) of being sensitized to cats. Neither cumulative exposure nor exposure at any other particular age was associated with either outcome. CONCLUSIONS AND CLINICAL RELEVANCE: The first year of life is the critical period during childhood when indoor exposure to dogs or cats influences sensitization to these animals.

Fabrication of a multi-applicable removable intraoral denture system for rodent research.

The objective was to engineer an inexpensive intraoral removable denture system for rodents that can be utilised in numerous oral health research applications. At the forefront is biofilm research related to Candida-associated denture stomatitis. Previously described intraoral devices are primitive and inadequate. The denture system was engineered consisting of a fixed part that is anchored to the posterior palate by orthodontic wires and acrylic resin and a removable part fitted to the anterior palate that is retained by magnets embedded in the fixed part. Both parts are custom fitted to the rodent palate by impression making and cast fabrication. Rats fitted with the intraoral denture system maintained body weight and normal activity with the device maintaining integrity and durability for upwards of 8 weeks. The denture system was used successfully to establish a working model of denture stomatitis. This newly engineered inexpensive intraoral removable denture system for rodents can be utilised in numerous oral health research applications, including denture-associated infections, biofilms and a variety of biomaterial applications. The removable portion is advantageous for longitudinal analyses and charging/discharging of biomaterials.

Factors associated with nonresponse to a computer-tailored asthma management program for urban adolescents with asthma.

BACKGROUND: The ability to identify potentially resistant participants early in the course of an intervention could inform development of strategies for behavior change and improve program effectiveness. OBJECTIVE: The objective of this analysis was to identify factors related to nonresponse (i.e., lack of behavior change) to an asthma management intervention for urban teenagers. The intervention targeted several behaviors, including medication adherence, having a rescue inhaler nearby, and smoking. METHODS: A discriminate analysis was conducted using data from a randomized trial of the intervention. Included in this analysis are participants who reported a physician diagnosis of asthma, completed a baseline questionnaire, were randomized to the treatment group, completed >or=2 of 4 educational sessions, and completed >or=2 of 3 follow-up questionnaires. Ninety students met criteria for inclusion in this subgroup analysis. RESULTS: In logistic regression models for medication adherence, nonresponse was related to low baseline asthma self-regulation, odds ratio = 3.6 (95% confidence interval = 1.3-9.5). In models for having an inhaler nearby, nonresponse was related to low baseline self-regulation and to rebelliousness, OR = 4.7 (1.6-13.2) and 5.6 (1.7-18.0), respectively. Nonresponse to smoking messages was related to rebelliousness, low emotional support, and low religiosity, ORs = 7.6 (1.8-32.3), 9.5 (1.4-63.5), and 6.6 (1.5-29.8) respectively. CONCLUSIONS: Certain variables had the ability to discriminate the likelihood of response from that of nonresponse to an asthma program for urban, African American adolescents with asthma. These variables can be used to identify resistant subgroups early in the intervention, allowing the application of specialized strategies through tailoring. These types of analyses can inform behavioral interventions.

Regulation of rat ovarian cell growth and steroid secretion.

A cultured rat ovarian cell line (31 A-F(2)) was used to study the effect of growth factors (epidermal growth factor [EGF] and fibroblast growth factor [FGF]), a survival factor (ovarian growth factor [OGF]), a hormone (insulin), and an iron-binding protein (transferring) on cell proliferation and steroid production under defined culture conditions. EGF and insulin were shown to be mitogenic (half-maximal response at 0.12 nM and 0.11 muM, respectively) for 31A-F(2) cells incubated in serum-free medium. EGF induced up to three doublings in the cell population, whereas insulin induced an average of one cell population doubling. FGF, OGF, and transferrin were found not to have any prominent effect on cell division when incubated individually with 31A-F(2) cells in serum-free medium. However, a combination of EGF, OGF, insulin, and transferrin stimulated cell division to the same approximate extent as cells incubated in the presence of 5 percent fetal calf serum. EGF or insulin did not significantly affect total cell cholesterol levels (relative to cells incubated in serum-free medium) when incubated individually with 31A-F(2) cells. However, cell cholesterol levels were increased by the addition of OGF (250 percent), FGF (370 percent), or a combination of insulin and EGF (320 percent). Progesterone secretion from 31A-F(2) cells was enhanced by EGF (25 percent), FGF (80 percent), and insulin (115 percent). However, the addition of a mitogenic mixture of EGF, OGF, insulin, and transferrin suppressed progesterone secretion 150 percent) below that of control cultures. These studies have permitted us to determine that EGF and insulin are mitogenic factors that are required for the growth of 31A-F(2) cells and that OGF and transferrin are positive cofactors that enhance growth. Also, additional data suggest that cholesterol and progesterone production in 31A-F(2) cells can be regulated by peptide growth factors and the hormone insulin.

Gender differences in the association of overweight and asthma morbidity among urban adolescents with asthma.

Asthma and obesity disproportionately affect US African-American youth. Among youth with asthma, obesity has been associated with poor control. The impact of gender on this association is unclear. We examined these relationships in a sample of urban, African-American adolescents with asthma. Questionnaires were used to identify high school students with asthma, and to examine the association of body mass index (BMI) to asthma morbidity, by gender. Of 5967 students completing questionnaires, 599 (10%) met criteria for asthma and 507 had data sufficient for inclusion in further analyses (46% male, mean age = 15.1 yr). Univariately, BMI > 85th percentile was significantly related only to reported emergency department visits (ED) and school days missed for any reason, Odds Ratio (95%Confidence Interval) = 1.7(1.1-2.7), p = 0.01 and 1.8(1.1-3.0), p = 0.01, respectively. A significant gender-BMI interaction (p < 0.05) was observed in multivariate models for ED visits, hospitalizations and school days missed for asthma. In gender-specific models, adjusted Risk Ratios for BMI > 85th and ED visits, hospitalizations, and school days missed because of asthma were 1.7(0.9-3.2), 6.6(3.1-14.6) and 3.6(1.8-7.2) in males. These associations were not observed in females. Gender modifies the association between BMI and asthma-related morbidity among adolescents with asthma. Results have implications for clinical management as well as future research.

Prenatal exposure to household pets influences fetal immunoglobulin E production.

BACKGROUND: Early life pet exposure may protect against allergic sensitization during childhood. Few studies have evaluated the effect of prenatal pet exposure on potential neonatal markers of allergic risk. OBJECTIVE: The aim of this study was to investigate whether maternal exposure to pets affects cord blood IgE levels in a population-based, general risk, ethnically mixed birth cohort. METHODS: Pet keeping during pregnancy was ascertained from women residing in a defined area of Wayne County Michigan and recruited from five staff model obstetric clinics. Maternal venous blood was analysed for total and allergen-specific IgE along with cord blood total IgE from 1049 infants. RESULTS: Compared with infants from households with no cats or dogs kept indoors during pregnancy, infants whose homes had either cats or dogs had significantly reduced mean cord IgE levels [0.34 IU/mL (95% CI 0.30-0.38) vs. 0.24 IU/mL (0.20-0.27), P=0.025]. Similar effects were apparent in cat-only households [0.21 IU/mL (0.16-0.27), P=0.020] and dog-only households [0.24 IU/mL (0.19-0.29), P=0.045]. There was no effect on results when excluding mothers who reported avoiding pets due to allergy-related concerns. CONCLUSION: Mothers with either cats or dogs in their home during pregnancy deliver children with lower cord blood IgE levels compared with mothers who do not live with these pets, supporting the hypothesis that pet exposure influences immune development in a manner that is protective for atopy and is operant even before birth.

Lactobacillus johnsonii supplementation attenuates respiratory viral infection via metabolic reprogramming and immune cell modulation.

Regulation of respiratory mucosal immunity by microbial-derived metabolites has been a proposed mechanism that may provide airway protection. Here we examine the effect of oral Lactobacillus johnsonii supplementation on metabolic and immune response dynamics during respiratory syncytial virus (RSV) infection. L. johnsonii supplementation reduced airway T helper type 2 cytokines and dendritic cell (DC) function, increased regulatory T cells, and was associated with a reprogrammed circulating metabolic environment, including docosahexanoic acid (DHA) enrichment. RSV-infected bone marrow-derived DCs (BMDCs) from L. johnsonii-supplemented mice had altered cytokine secretion, reduced expression of co-stimulatory molecules, and modified CD4+ T-cell cytokines. This was replicated upon co-incubation of wild-type BMDCs with either plasma from L. johnsonii-supplemented mice or DHA. Finally, airway transfer of BMDCs from L. johnsonii-supplemented mice or with wild-type derived BMDCs pretreated with plasma from L. johnsonii-supplemented mice reduced airway pathological responses to infection in recipient animals. Thus L. johnsonii supplementation mediates airway mucosal protection via immunomodulatory metabolites and altered immune function.

Neuroblastoma: case-control analysis of birth characteristics.

The peak incidence of neuroblastoma during early infancy indicates that prenatal factors may play a role in the pathogenesis of this disease. A population-based case-control study was conducted comparing birth certificate data of 157 children who later died from neuroblastoma in Texas with 314 controls randomly selected from all Texas live births. Analysis of birth certificate data revealed a protective relative risk estimate for preterm births (less than 37-wk gestation), with an overall odds ratio of 0.29 (95% confidence limits of 0.10-0.86). This effect was independent of birth weight and ethnic group. A statistically significant odds ratio of 3.22 was detected for term babies whose birth weight was low. The findings suggest that the fetus is susceptible to an in utero oncogenic initiator or promoter during the last 4 weeks of gestation.

Race and differences in breast cancer survival in a managed care population.

BACKGROUND: African-American women with breast cancer have poorer survival than European-American women. After adjustment for socioeconomic variables, survival differences diminish but do not disappear, possibly because of residual differences in health care access, biology, or behavior. This study compared breast cancer survival in African-American and European-American women with similar health care access. METHODS: We measured survival in women with breast cancer who are served by a large medical group and a metropolitan Detroit health maintenance organization where screening, diagnosis, treatment, and follow-up are based on standard practices and mammography is a covered benefit. We abstracted data on African-American and European-American women who had been diagnosed with breast cancer from January 1986 through April 1996 (n = 886) and followed these women for survival through April 1997 (137 deaths). RESULTS: African-American women were diagnosed at a later stage than were European-American women. Median follow-up was 50 months. Five-year survival was 77% for African-American and 84% for European-American women. The crude hazard ratio for African-American women relative to European-American women was 1.6 (95% confidence interval [CI] = 1.1-2.2). Adjusting only for stage, the hazard ratio was 1.3 (95% CI = 0.9-1.9). Adjusting only for sociodemographic factors (age, marital status, and income), the hazard ratio was 1.2 (95% CI = 0.8-1.9). After adjusting for age, marital status, income, and stage, the hazard ratio was 1.0 (95% CI = 0.7-1.5). CONCLUSION: Among women with similar medical care access since before their diagnoses, we found ethnic differences in stage of breast cancer at diagnosis. Adjustment for this difference and for income, age, and marital status resulted in a negligible effect of race on survival.

Ethnic patterns of Hodgkin's disease incidence among children and adolescents in the United States, 1973-82.

The descriptive epidemiologic findings were summarized on 1,109 patients (white, black, and Hispanic) under 20 years of age who were diagnosed with Hodgkin's disease as reported to the Surveillance, Epidemiology, and End Results ("SEER") Program of the National Cancer Institute from 1973 to 1982. Across all ethnic strata, incidence rates increased with advancing age at diagnosis, with white adolescents 15-19 years old exhibiting the highest rates (male, 3.67; female, 4.18). Gender difference among children 0-14 years of age was most evident in blacks (male:female ratio: 4.0 for blacks, 1.0 for whites). Highest adolescent:childhood ratios of incidence rates were noted for females (5.81 for whites and 8.29 for New Mexico Hispanics) and lowest, for Hispanic males (1.25, New Mexico; 2.15, Puerto Rico). Whites exhibited the highest percentage of the nodular sclerosis histologic subtype (65%) and Hispanics, the lowest (45%). Conversely, Hispanics had higher rates of histologic types associated with a poorer prognosis (mixed cellularity and lymphocyte depletion). These differing age and histologic patterns were consistent with previously described international patterns of disease occurrence. Analysis of secular trends for whites from 1969 to 1982 revealed relatively stable rates for youngest ages and male adolescents. Rates increased over time for white female adolescents, but the trend was not statistically significant.

Maternal group B Streptococcus and the infant gut microbiota.

Early patterns of gut colonization may predispose children to adult disease. Exposures in utero and during delivery are associated with the infant gut microbiome. Although ~35% of women carry group B strep (GBS; Streptococcus agalactiae) during pregnancy, it is unknown if GBS presence influences the infant gut microbiome. As part of a population-based, general risk birth cohort, stool specimens were collected from infant's diapers at research visits conducted at ~1 and 6 months of age. Using the Illumina MiSeq (San Diego, CA) platform, the V4 region of the bacterial 16S rRNA gene was sequenced. Infant gut bacterial community compositional differences by maternal GBS status were evaluated using permutational multivariate analysis of variance. Individual operational taxonomic units (OTUs) were tested using a zero-inflated negative binomial model. Data on maternal GBS and infant gut microbiota from either 1 (n=112) or 6-month-old stool (n=150) specimens was available on 262 maternal-child pairs. Eighty women (30.5%) were GBS+, of who 58 (72.5%) were given intrapartum antibiotics. After adjusting for maternal race, prenatal antifungal use and intrapartum antibiotics, maternal GBS status was statistically significantly associated with gut bacterial composition in the 6 month visit specimen (Canberra R 2=0.008, P=0.008; Unweighted UniFrac R 2=0.010, P=0.011). Individual OTU tests revealed that infants of GBS+ mothers were significantly enriched for specific members of the Clostridiaceae, Ruminococcoceae, and Enterococcaceae in the 6 month specimens compared with infants of GBS- mothers. Whether these taxonomic differences in infant gut microbiota at 6 months lead to differential predisposition for adult disease requires additional study.

Inhibition of proteoglycan synthesis by hydrogen peroxide in cultured bovine articular cartilage.

Oxygen-derived reactive species, generated enzymatically by the action of xanthine oxidase upon hypoxanthine, significantly inhibit proteoglycan synthesis by cultured bovine articular cartilage (Bates, E.J., Lowther, D.A. and Handley, C.J. (1984) Ann. Rheum. Dis. 43, 462-469). Here we extend these investigations and show, through the use of catalase and the specific iron chelator diethylenetriaminepentaacetic acid, that the active species involved is H2O2 and not the hydroxyl radical. Incubations of cartilage with H2O2 at concentrations of 1 X 10(-4) M and above are also inhibitory to proteoglycan synthesis. Subsequent recovery of the tissue is dependent upon the initial dose of xanthine oxidase or H2O2. Xanthine oxidase at 84 mU per incubation results in a prolonged inhibition of proteoglycan synthesis which is still apparent after 14 days in culture. Lower concentrations of xanthine oxidase (21-66 mU) are inhibitory to proteoglycan synthesis, but the tissue is able to synthesise proteoglycans at near normal rates after 3 days in culture. The inhibition of proteoglycan synthesis by 1 X 10(-4) M H2O2 is completely reversed after 5 days in culture, whereas 1 X 10(-3) M H2O2 results in a more prolonged inhibition. The synthesis of the proteoglycan core protein is inhibited, but the ability of the newly formed proteoglycans to aggregate with hyaluronic acid is unimpaired.