Elisabet Johansson

High environmental relative moldiness index during infancy as a predictor of asthma at 7 years of age

BACKGROUND Mold exposures may contribute to the development of asthma, but previous studies have lacked a standardized approach to quantifying exposures. OBJECTIVE To determine whether mold exposures at the ages of 1 and/or 7 years were associated with asthma at the age of 7 years. METHODS This study followed up a high-risk birth cohort from infancy to 7 years of age. Mold was assessed by a DNA-based analysis for the 36 molds that make up the Environmental Relative Moldiness Index (ERMI) at the ages of 1 and 7 years. At the age of 7 years, children were evaluated for allergic sensitization and asthma based on symptom history, spirometry, exhaled nitric oxide, and airway reversibility. A questionnaire was administered to the parent regarding the childs asthma symptoms and other potential cofactors. RESULTS At the age of 7 years, 31 of 176 children (18%) were found to be asthmatic. Children living in a high ERMI value (≥5.2) home at 1 year of age had more than twice the risk of developing asthma than those in low ERMI value homes (<5.2) (adjusted odds ratio [aOR], 2.6; 95% confidence interval [CI], 1.10-6.26). Of the other covariates, only parental asthma (aOR, 4.0; 95% CI, 1.69-9.62) and allergic sensitization to house dust mite (aOR, 4.1; 95% CI, 1.55-11.07) were risk factors for asthma development. In contrast, air-conditioning at home reduced the risk of asthma development (aOR, 0.3; 95% CI, 0.14-0.83). A high ERMI value at 7 years of age was not associated with asthma at 7 years of age. CONCLUSIONS Early exposure to molds as measured by ERMI at 1 year of age, but not 7 years of age, significantly increased the risk for asthma at 7 years of age.

Visually observed mold and moldy odor versus quantitatively measured microbial exposure in homes

The main study objective was to compare different methods for assessing mold exposure in conjunction with an epidemiologic study on the development of childrens asthma. Homes of 184 children were assessed for mold by visual observations and dust sampling at childs age 1 (Year 1). Similar assessment supplemented with air sampling was conducted in Year 7. Samples were analyzed for endotoxin, (1-3)-β-D-glucan, and fungal spores. The Mold Specific Quantitative Polymerase Chain Reaction assay was used to analyze 36 mold species in dust samples, and the Environmental Relative Moldiness Index (ERMI) was calculated. Homes were categorized based on three criteria: 1) visible mold damage, 2) moldy odor, and 3) ERMI. Even for homes where families had not moved, Year 7 endotoxin and (1-3)-β-d-glucan exposures were significantly higher than those in Year 1 (p<0.001), whereas no difference was seen for ERMI (p=0.78). Microbial concentrations were not consistently associated with visible mold damage categories, but were consistently higher in homes with moldy odor and in homes that had high ERMI. Low correlations between results in air and dust samples indicate different types or durations of potential microbial exposures from dust vs. air. Future analysis will indicate which, if any, of the assessment methods is associated with the development of asthma.

Lipid metabolism and body composition in Gclm(-/-) mice

In humans and experimental animals, high fat diets (HFD) are associated with risk factors for metabolic diseases, such as excessive weight gain and adiposity, insulin resistance and fatty liver. Mice lacking the glutamate-cysteine ligase modifier subunit gene (Gclm(-/-)) and deficient in glutathione (GSH), are resistant to HFD-mediated weight gain. Herein, we evaluated Gclm-associated regulation of energy metabolism, oxidative stress, and glucose and lipid homeostasis. C57BL/6J Gclm(-/-) mice and littermate wild-type (WT) controls received a normal diet or an HFD for 11 weeks. HFD-fed Gclm(-/-) mice did not display a decreased respiratory quotient, suggesting that they are unable to process lipid for metabolism. Although dietary energy consumption and intestinal lipid absorption were unchanged in Gclm(-/-) mice, feeding these mice an HFD did not produce excess body weight nor fat storage. Gclm(-/-) mice displayed higher basal metabolic rates resulting from higher activities of liver mitochondrial NADH-CoQ oxidoreductase, thus elevating respiration. Although Gclm(-/-) mice exhibited strong systemic and hepatic oxidative stress responses, HFD did not promote glucose intolerance or insulin resistance. Furthermore, HFD-fed Gclm(-/-) mice did not develop fatty liver, likely resulting from very low expression levels of genes encoding lipid metabolizing enzymes. We conclude that Gclm is involved in the regulation of basal metabolic rate and the metabolism of dietary lipid. Although Gclm(-/-) mice display a strong oxidative stress response, they are protected from HFD-induced excessive weight gain and adipose deposition, insulin resistance and steatosis.

Oral benzo[a]pyrene-induced cancer: two distinct types in different target organs depend on the mouse Cyp1 genotype

Benzo[a]pyrene (BaP) is a prototypical polycyclic aromatic hydrocarbon (PAH) found in combustion processes. Cytochrome P450 1A1 and 1B1 enzymes (CYP1A1 and CYP1B1) can both detoxify PAHs and activate them to cancer‐causing reactive intermediates. Following high dosage of oral BaP (125 mg/kg/day), ablation of the mouse Cyp1a1 gene causes immunosuppression and death within ∼28 days, whereas Cyp1(+/+) wild‐type mice remain healthy for >12 months on this regimen. In this study, male Cyp1(+/+) wild‐type, Cyp1a1(−/−) and Cyp1b1(−/−) single‐knockout and Cyp1a1/1b1(−/−) double‐knockout mice received a lower dose (12.5 mg/kg/day) of oral BaP. Tissues from 16 different organs—including proximal small intestine (PSI), liver and preputial gland duct (PGD)—were evaluated; microarray cDNA expression and >30 mRNA levels were measured. Cyp1a1(−/−) mice revealed markedly increased CYP1B1 mRNA levels in the PSI, and between 8 and 12 weeks developed unique PSI adenomas and adenocarcinomas. Cyp1a1/1b1(−/−) mice showed no PSI tumors but instead developed squamous cell carcinoma of the PGD. Cyp1(+/+) and Cyp1b1(−/−) mice remained healthy with no remarkable abnormalities in any tissue examined. PSI adenocarcinomas exhibited striking upregulation of the Xist gene, suggesting epigenetic silencing of specific genes on the Y‐chromosome; the Rab30 oncogene was upregulated; the Nr0b2 tumor suppressor gene was downregulated; paradoxical overexpression of numerous immunoglobulin kappa‐ and heavy‐chain variable genes was found—although the adenocarcinoma showed no immunohistochemical evidence of being lymphatic in origin. This oral BaP mouse paradigm represents an example of “gene‐environment interactions” in which the same exposure of carcinogen results in altered target organ and tumor type, as a function of just 1 or 2 globally absent genes.

Protection from olanzapine-induced metabolic toxicity in mice by acetaminophen and tetrahydroindenoindole

Objective:In mice and in humans, treatment with the second-generation antipsychotic drug olanzapine (OLZ) produces excessive weight gain, adiposity and secondary metabolic complications, including loss of glucose and insulin homeostasis. In mice consuming a high-fat (HF) diet, a similar phenotype develops, which is inhibited by the analgesic acetaminophen (APAP) and by the antioxidant tetrahydroindenoindole (THII). Therefore, we examined the ability of APAP and THII to prevent metabolic changes in mice receiving OLZ.Design and Measurement:C57BL/6J mice received either a normal diet or a HF diet, and were administered daily dosages of OLZ (3 mg kg−1 body weight), alone or with APAP (30 mg kg−1 body weight) or THII (4.5 mg kg−1 body weight), for 10 weeks. Parameters of body composition and metabolism, including glucose and insulin homeostasis and oxidative stress, were examined.Results:OLZ treatment doubled the HF diet-induced increases in body weight and percent body fat. These increases were partially prevented by both APAP and THII, although food consumption was constant in all groups. The THII protection was associated with an increase in whole body and mitochondrial respiration. OLZ also exacerbated, and both APAP and THII prevented, HF diet-induced loss of glucose tolerance and insulin resistance. As increased body fat promotes insulin resistance by a pathway involving oxidative stress, we evaluated production of reactive oxygen and lipid peroxidation in white adipose tissue (WAT). HF diet caused an increase in lipid peroxidation, NADPH-dependent O2 uptake and H2O2 production, which were further exacerbated by OLZ. APAP, THII and the NADPH oxidase inhibitor, diphenyleneiodonium chloride, each abolished oxidative stress in WAT.Conclusions:We conclude that both APAP and THII intervene in the development of obesity and metabolic complications associated with OLZ treatment.

Early onset senescence occurs when fibroblasts lack the glutamate-cysteine ligase modifier subunit.

Cellular senescence is the irreversible entry of cells into growth arrest. Senescence of primary cells in culture has long been used as an in vitro model for aging. Glutamate-cysteine ligase (GCL) controls the synthetic rate of the important cellular antioxidant glutathione (GSH). The catalytic subunit of GCL, GCLC, is catalytically active and essential for life. By contrast the modifier subunit of GCL, GCLM, is dispensable in mice. Although it is recognized that GCLM increases the rate of GSH synthesis, its physiological role is unclear. Herein, we show that loss of Gclm leads to premature senescence of primary murine fibroblasts as characterized by: (a) diminished growth rate, (b) cell morphology consistent with senescence, (c) increases in senescence-associated beta-galactosidase activity, and (d) cell cycle arrest at the G(1)/S and G(2)/M boundaries. These changes are accompanied by increased intracellular ROS, accumulation of DNA damage, and induction of p53 and p21 proteins. We also found that N-acetylcysteine increases intracellular GSH and prevents premature senescence in Gclm(-/-) cells. These results suggest that the control of GCLM, which in turn controls aspects of the cellular redox environment via GSH, is important in determining the replicative capacity of the cell.

Streptomycetes in house dust: associations with housing characteristics and endotoxin

In addition to mold, indoor bioaerosols also contain bacterial components that may have implications for human health. Endotoxin is a cell wall component in Gram-negative bacteria present at varying levels indoors that has been found to have respiratory health implications. Streptomyces is a large genus of Gram-positive bacteria, and some species have been shown to produce inflammatory reactions in vitro and in vivo. The aim of this study was to determine predictors of streptomycetes levels in house dust and to compare the variation in streptomycetes levels with that in endotoxin levels. Dust was collected by floor vacuuming from 178 homes in the Cincinnati metropolitan area. Streptomycetes levels were measured by quantitative PCR, and endotoxin was assayed by the Limulus amebocyte lysate method. Associations between home characteristics and bacterial contaminants, expressed as concentration and load, were investigated through multiple regression analyses. The presence of two or more dogs was a strong predictor of both streptomycetes and endotoxin levels. Season of dust collection and levels of outdoor molds were predictors of streptomycetes but not endotoxin levels. In contrast, number of inhabitants was a significant predictor of endotoxin load only. Neither streptomycetes nor endotoxin levels were associated with metrics of moisture damage.

Glutathione deficient C57BL/6J mice are not sensitized to ozone-induced lung injury

In this study we examined the role of the antioxidant glutathione (GSH) in pulmonary susceptibility to ozone toxicity, utilizing GSH deficient C57BL/6J mice that lack the expression of glutamate-cysteine ligase modifier subunit (GCLM). Gclm(-/-) knockout mice had 70% GSH depletion in the lung. Gclm(+/+) wild-type and Gclm(-/-) mice were exposed to either 0.3 ppm ozone or filtered air for 48h. Ozone-induced lung hyperpermeability, as measured by total protein concentration in bronchoalveolar lavage fluid, was surprisingly lower in Gclm(-/-) mice than in wild-type mice. Lung hyperpermeability did not correlate with the degree of neutrophilia or with inflammatory gene expression. Pulmonary antioxidant response to ozone, assessed by increased mRNA levels of metallothionein 1 and 2, alpha-tocopherol transporter protein, and solute carrier family 23 member 2 (sodium-dependent vitamin C transporter) was greater in Gclm(-/-) mice than in Gclm(+/+) mice. These results suggest that compensatory augmentation of antioxidant defenses in Gclm(-/-) mice may confer increased resistance to ozone-induced lung injury.

Inactivation of Aerosolized Viruses in Continuous Air Flow with Axial Heating

Thermal inactivation of viruses has been studied in relevance to food sterilization, water purification, and other “non-aerosol” applications, in which heat treatment is applied for a relatively long time. No data are available on the inactivation of airborne viruses exposed to dry heat for a short time, although this is relevant to bio-defense and indoor air quality control. In this study, we investigated inactivation of aerosolized MS2 viruses in a continuous air flow chamber with axial heating resulted from exposures during ∼ 0.1–1 s. For an airborne virion, the characteristic exposure temperature, T e , was defined utilizing the air temperature profiles in the chamber. The tests were conducted at two air flow rates, Q, which allowed for establishing different thermal flow regimes and exposure time intervals. The experimentally determined inactivation factor, IF, was subjected to correction to account for the temperature profiles. At T e up to ∼ 90°C (Q = 18 L/min) and up to ∼ 140°C (Q = 36 L/min), the loss of viral infectivity was relatively modest (≤ 10). However, IF increased exponentially as T e rose from ∼ 90°C to ∼ 160°C (for 18 L/min) or from ∼ 140°C to ∼ 230°C (for 36 L/min). Under specific thermal exposure conditions (∼ 170°C and ∼ 250°C, respectively), IF exceeded ∼ 2.4 × 104 (∼ 99.996% infectivity loss)—the maximum quantifiable in this study. The airborne MS2 virions exposed to hot air for < 1 s were found to have survived much higher temperatures than those subjected to thermal treatment in liquid for minutes or hours. The findings are significant for establishing limitations of the heat-based bioaerosol control methods.

Frequency of Ha-ras-1 gene mutations inversely correlated with furan dose in mouse liver tumors

Liver tumors were induced in infant male B6C3F1 mice by preweaning administration of furan, either as a single dose of 400 mg/kg body weight or six doses of 200 mg/kg body weight. Six doses of 200 mg/kg furan resulted in an increased incidence and multiplicity of liver tumors relative to the multiple‐dose vehicle control group and the single‐dose furan group. In the single‐dose group, there was an increase in overall tumor multiplicity but not prevalence of liver tumors. After polymerase chain reaction amplification of isolated DNA, slot‐blot oligonucleotide hybridization was used to screen for mutations at known mutational hot‐spots in the first three exons of Ha‐ras‐1 (Hras1). The relative frequency of Hras1 activation was 82% in the 28 tumors analyzed from the single‐dose group and 32% in the 28 tumors analyzed from the multiple‐dose group. The lack of histomorphologic evidence of chronic cytotoxicity in the livers and the pattern of Hras1 activation suggest that a genotoxic mode of action is responsible for at least part of the hepatocarcinogenicity of furan in B6C3F1 mice. These findings confirm previously documented hepatocarcinogenicity of furan in B6C3F1 mice and provide evidence that carcinogen dose may influence the frequency of Hras1 activation in mouse liver tumors. Mol. Carcinog. 18:199–205, 1997.