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Physiol. Genomics 30: 262-270, 2007. First published May 8, 2007; doi:10.1152/physiolgenomics.00232.2006
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Received 23 October 2006; accepted in final form 2 May 2007.
Physiological Genomics 30:262-270 (2007)
1094-8341/06 $8.00 © 2007 American Physiological Society

A genetic mouse model to investigate hyperoxic acute lung injury survival

Daniel R. Prows 1,2, Amanda P. Hafertepen 2, William J. Gibbons, Jr. 2, Abby V. Winterberg 2 and Todd G. Nick 1,3

1 Department of Pediatrics, University of Cincinnati College of Medicine, Children's Hospital Medical Center, Cincinnati, Ohio
2 Division and Program in Human Genetics, Children's Hospital Medical Center, Cincinnati, Ohio
3 Center for Epidemiology and Biostatistics, Children's Hospital Medical Center, Cincinnati, Ohio


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Acute lung injury (ALI) is a devastating disease that maintains a high mortality rate, despite decades of research. Hyperoxia, a universal treatment for ALI and other critically ill patients, can itself cause pulmonary damage, which drastically restricts its therapeutic potential. We stipulate that having the ability to use higher levels of supplemental O2 for longer periods would improve recovery rates. Toward this goal, a mouse model was sought to identify genes contributing to hyperoxic ALI (HALI) mortality. Eighteen inbred mouse strains were screened in continuous >95% O2. A significant survival difference was identified between sensitive C57BL/6J and resistant 129X1/SvJ strains. Although resistant, only one-fourth of 129X1/SvJ mice survived longer than any C57BL/6J mouse, demonstrating decreased penetrance of resistance. A survival time difference between reciprocal F1 mice implicated a parent-of-origin (imprinting) effect. To further evaluate imprinting and begin to delineate the genetic components of HALI survival, we generated and phenotyped offspring from all four possible intercrosses. Segregation analysis supported maternal inheritance of one or more genes but paternal inheritance of one or more contributor genes. A significant sex effect was demonstrated, with males more resistant than females for all F2 crosses. Survival time ranges and sensitive-to-resistant ratios of the different F2 crosses also supported imprinting and predicted that increased survival is due to dominant resistance alleles contributed by both the resistant and sensitive parental strains. HALI survival is multigenic with a complex mode of inheritance, which should be amenable to genetic dissection with this mouse model.

complex trait; imprinting; segregation analysis; mean survival time


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
THE PROGRESSION of early acute lung injury (ALI) to its most severe form, acute respiratory distress syndrome (ARDS), represents a continuum of a devastating and, too often, lethal condition that has been associated with numerous causes. Decades of research have led to significant improvement in survival rates, yet ALI mortality remains around 40%, suggesting that current supportive and therapeutic treatment strategies may be reaching their limits. Hyperoxia, a widely used modality of life-saving intensive care, can itself induce oxidative injury, with the lung representing the primary target organ. Sustained hyperoxia leads to damaging pulmonary effects that progress through inflammation, fluid accumulation, lung failure, and death. Currently, such pulmonary toxicity markedly limits the clinical potential of supplemental O2 therapy in these patients. We stipulate that having the ability to use continuous high-dose O2, without the need to consider its potential oxidative damage, would allow many more critically ill patients the time needed to heal and recover. Toward this goal, we sought a genetic mouse model for further study.

Because of the detrimental pulmonary effects of O2, hyperoxic ALI (HALI) has become a prototypical model to study ALI and ARDS in experimental animals (2, 8, 9, 11, 16, 19, 24, 39, 45). The pathophysiology of HALI in murines has been described in detail (1, 4, 12, 34), with ALI and respiratory distress established as a primary cause of death in long-term exposures (1, 4, 12, 34). Although much is known of the lung pathology induced by O2, very little is known about the specific genes or gene products associated with O2 susceptibility, tolerance, or the mechanisms of disease progression and death. In fact, more than a hundred potential causative factors for ALI have been proposed and tested in humans and animal models, but the results from studies on even the most promising therapeutic agents affecting these candidate genes have had little impact on survival rates in humans. Therefore, different strategies are vital to advance our knowledge of the mechanisms of ALI morbidity and mortality.

Inbred mice have been used in genetic studies of ALI to circumvent many of the inherent problems in human populations (10, 15, 17, 21, 22, 27). These studies have evaluated one or more intermediate phenotypes (e.g., inflammation, hyperpermeability, or number of lavaged cells) to represent a typical characteristic of ALI pathology. To date, however, none of these early indicators has been highly predictive of ALI severity or survival. Because ALI mortality is the definitive outcome that must be improved, we have used survival time as the end phenotype, with a long-term goal aimed at identifying critical genes affecting oxidant-induced ALI mortality. Previously, we reported on the genetic analysis of ozone (29, 31)- and nickel (30)-induced ALI survival. For both oxidative lung injuries, A/J (A) mice are sensitive and C57BL/6J (B) mice are resistant. On the contrary, many independent labs have reported that B-strain mice are quite sensitive to the lethal effects of >95% O2 (3, 11, 37, 40, 41). Thus, although one or more genes may overlap for these different oxidants, the sets of genes affecting survival to ozone- or nickel-induced ALI appear to differ from the set of genes controlling HALI survival.

To address the high mortality rate of ALI, we have established a mouse model to delineate the genetic factors contributing to differential HALI strain survival. In a screen of 18 inbred lines of mice, we selected B-strain mice as sensitive to the lethal effects of hyperoxia, succumbing with severe ALI between 4 and 5 days. 129X1/SvJ (S) inbred mice were selected as the resistant strain for our model. S mice are significantly more resistant, with some surviving at least 10 days. Ultimately, as seen with the B mice, S mice also died with severe ALI. Detailed assessments of large first (F1) and second (F2) generations derived from the B and S strains demonstrated that HALI survival time is multigenic with a complex inheritance pattern, which includes maternal inheritance and decreased penetrance of the resistance trait. Recombinant F2 mice exhibited significant sex and cross differences, revealing that the parent of origin also influences survival time. Interestingly, at least one gene associated with resistance is contributed by the sensitive B strain, which can further increase survival time in F2 offspring. This mouse model should be useful to identify genes affecting strain survival time in hyperoxia, and may be useful in subsequent mechanistic studies to assess O2 tolerance or HALI development and progression.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Mice.
To determine a mouse model of differential survival in continuous >95% O2, we screened females of the following 18 inbred mouse strains for mean survival time (MST): 129P3/J (P; n = 18), 129S1/SvImJ (n = 8), 129T2/SvEmsJ (n = 8), 129X1/SvJ (S; n = 19), A/J (A; n = 22), AKR/J (n = 6), Balb/cByJ (n = 8), Balb/cJ (n = 12), C3H/HeJ (n = 12), C3HeB/FeJ (n = 6), C3H/HeOuJ (n = 6), C57BL/6J (B; n = 18), CBA/J (n = 6), DBA/2J (n = 6), FVB/NJ (n = 12), MRL/MpJ (n = 8), NZW/LacJ (n = 8), and SJL/J strains (n = 6). All mice were obtained from the Jackson Laboratory (Bar Harbor, ME) at 5–7 wk of age and maintained in a virus- and pathogen-free environment with a 14:10-h on-off light cycle. A pair of polar-responding strains was identified for use as a mouse model of HALI survival. In this model, B-strain mice are sensitive whereas 129X1/SvJ (S strain) mice are significantly more resistant to HALI mortality. [Note: We used the letter "S" to abbreviate the 129X1/SvJ strain because we did not want to use a number or the more obvious letter "X," a common abbreviation for "cross" and the "X chromosome" in genetic studies.] After the B-S mouse model was established, crosses of these strains were used in segregation studies to establish trait heritability and the likely mode of inheritance, and to gain an estimate of the number of genes controlling HALI survival. To assess potential differences in breeding patterns, the (BxS)F1 (or B.S) and (SxB)F1 (or S.B) reciprocal hybrids were generated and phenotyped. There were no differences in breeding performance, but phenotyping results for reciprocal F1 mice supported a parent-of-origin effect, because the MST of B.S mice differed significantly from that of S.B mice. To further assess this parent-of-origin effect, all four possible F2 crosses (i.e., BS.BS, BS.SB, SB.BS, and SB.SB; female F1 listed first) were generated and phenotyped for segregation analysis of the survival time phenotype. Over the course of these studies, the total numbers of parental strain mice exposed were B = 96 and S = 180.

Hyperoxic atmosphere generation and exposure.
Mice in their original shoe box cages (up to 4 mice per cage, with food and water ad libitum) were placed inside a 0.13-m3 Plexiglas inhalation chamber (special fabrication; Stellar Plastics, Detroit, MI) and exposed to >95% O2 until death. The O2 concentration of each chamber was continuously monitored and self-regulated with a ProOx 110 portable O2 monitor (Biospherix, Redfield, NY). The monitors were calibrated before each exposure as needed with a two-point calibration method of room air and 100% O2. To allow continuous turnover of O2 and to prevent the buildup of CO2 and ammonia, the chamber air was exhausted out of the building by a duct that attached to the in-house ventilation system. Exposures were closely monitored, such that the survival time for each mouse was within 5% error. Up to three exposures (with up to 36 mice per exposure chamber) could be performed at one time, allowing a maximum of 108 mice to be tested every 2 wk. For mice obtained from the Jackson Laboratory, exposures were initiated at least 1 wk after receipt, but by 12 wk of age. Mice bred in-house were exposed between 6 and 12 wk of age. To avoid sudden hypoxia-related seizures and premature mortalities, the chambers were not opened for the duration of the exposure, which continued until all mice within the chamber were dead. After death of all mice within the chamber, mice were numbered and a tail sample was retrieved from each mouse and stored at –80°C for subsequent genotype studies. Breeding and exposures of mice included in these studies occurred over >4 yr, covering all four seasons. No significant differences in survival times were noted between seasons. Mice were handled in accordance with protocols approved by the Institutional Animal Care and Use Committee of Cincinnati Children's Hospital Medical Center.

Phenotype designation.
As a different method to determine the likely mode of trait inheritance, individual F2 mice were qualitatively phenotyped as "sensitive" or "resistant" to HALI-induced mortality. Because all mice eventually die in continuous oxygen, "resistant" in this context is a relative term, based on survival times compared with those of more sensitive mice. Although such a categorical phenotypic description for individual mice could be problematic for a quantitative trait, this designation is useful as a general guideline to identify differences in phenotypes and phenotype ratios among the various breeding schemes. The criterion for phenotype designation (i.e., sensitive or resistant) was established by dividing the total F2 population (n = 840) into quintiles (n = 168 each), which yielded a survival time <99 h (lowest quintile) for the sensitive phenotype and >153 h (upper quintile) for a resistant phenotype. Importantly, this resistance cutoff was above the survival range of the sensitive B strain (i.e., longest surviving B mouse was 150 h).

Estimation of heritability and number of genes involved in the survival trait.
Broad sense heritability, which includes variance due to dominance effects and nonlinear interactions between different genes, was determined with a variation of the general formula {sigma}G2/({sigma}G2 + {sigma}E2), where {sigma}G2 is the genetic variance and {sigma}E2 is the environmental variance. Specifically, {sigma}F22 was used for the total genetic variance ({sigma}G2), and {sigma}F22 + (nB{sigma}B2 + nS{sigma}S2 + nF1{sigma}F12/N), the weighted average (n = sample size of each line; N = total sample size) of the variances of parental (B and S) and F1 populations, was used to calculate {sigma}E2 (43). Narrow sense heritability (h2) of the survival trait was estimated with h2 = {sigma}F22 – [({sigma}B2 + {sigma}S2 + {sigma}BS2 + {sigma}SB2)/4]/{sigma}F22. To estimate the effective number of genes that influence the survival time difference in hyperoxia, we used the Castle-Wright equation for F2 mice: k = (P2 – F1)2/4·(|{sigma}F22–{sigma}F12|), where k is an estimate of the number of independent loci, P2 and F1 are the MSTs of B and total F1 mice, respectively, and {sigma}F22 and {sigma}F12 are computed variances of the total F2 and F1 cohorts, respectively. These estimates assume that 1) the genes are unlinked, 2) the genes are semidominant and contribute equally to the trait, and 3) all resistance or sensitivity alleles for the trait occur in same inbred strain.

Statistical analysis.
MSTs of male, female, and male plus female parental and reciprocal F1 mice were compared for differences by two-way analysis of variance (ANOVA) with interaction between the two factors. Similarly, male, female, and male plus female F2 mice were compared for total F2 mice (all F2 groups combined) and among and within the four different F2 mating groups (BS.BS, BS.SB, SB.BS, and SB.SB). The interaction term between sex and mating groups was included when significance level was <0.20 and Tukey's post hoc test adjusted for pairwise comparisons when main effects were P ≤ 0.05. In addition, two focused comparisons of MSTs were conducted for males, females, and total mice derived from combining F2 groups with a common F1 dam or F1 sire (i.e., B.S dam vs. S.B dam and B.S sire vs. S.B sire). Besides comparison of MSTs of reciprocal F1 and F2 groups, a parent-of-origin effect was also explored by comparing the sensitive-to-resistant phenotype ratios (S:R) among the F2 mating groups. Sensitive phenotypes were defined as MSTs falling in the lowest quintile (<99 h) and resistant phenotypes in the highest quintile (>153 h). {chi}2-Tests were used to compare the observed S:R to the null hypothesis value (1.0) for each of the F2 subpopulations. Wilcoxon-Mann-Whitney tests were used to compare male-female S:R within each F2 subpopulation. In all cases, statistical significance was accepted at P ≤ 0.05, after correcting for multiple testing.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 GRANTS
 REFERENCES
 
Identifying the mouse model.
To determine a mouse model of HALI for subsequent genetic analysis of survival time, female mice from 18 inbred strains were exposed to continuous >95% O2; MSTs are presented in Fig. 1. Overall, the strains displayed a continuous phenotype distribution pattern, with MSTs of the highest and lowest responders ranging near twofold. In this initial study of females, only the S strain was markedly resistant compared with the other strains, with a MST of 182 h (n = 19). Four substrains of the 129-derived inbred lines were tested; nomenclature for the 129 substrains is as described by Festing et al. (13). Three of these 129 substrains, namely, 129P3/J (P), 129S1/SvImJ, and 129T2/SvEmsJ, were the most sensitive strains tested. Surprisingly, the S substrain (129X1/SvJ) was initially the most resistant of all strains tested. Of the other strains tested, the AKR/J, SJL/J, and B strains were also sensitive (MST ≤ 106 h). The B strain was selected as the sensitive line for further study, because of the abundant genetic data that exist for this strain and its relatively high number of known polymorphisms with the S strain that would help in the ensuing genome-wide analyses. Thus the B-S mouse model was established for subsequent genetic studies. Although the other 129 substrains are the most sensitive, they are genetically very similar to the S strain and estimated to share at least 80–90% of their genomes (33, 36). This makes the identification of polymorphic markers—which are needed to track parental inheritance—extremely difficult (microsatellite markers) or very expensive [single nucleotide polymorphism (SNP) analysis]. Interestingly, the A/J (A) and B strains can be considered another polar-responding model for use in genetic studies. A-strain mice are relatively resistant to hyperoxia, revealing that the B and A survival times in hyperoxia are opposite those in other oxidative exposures tested, including ozone (31), nickel sulfate (30), and polytetrafluoroethylene (Teflon) fumes (42), where the B strain is resistant and the A strain is sensitive.


Figure 1
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  		Fig. 1. Strain phenotype pattern for hyperoxic acute lung injury (HALI) survival time. Eighteen strains of inbred mice were tested in >95% continuous O2, and mean survival times (MSTs) were calculated. For this initial screen, all mice were females and were purchased from the Jackson Laboratory (Bar Harbor, ME). The MST for each strain is shown above the error bar (SE), and the number of mice exposed for each line is shown within each bar. At least 6 mice of each strain were tested. Interestingly, three 129 substrains [light gray bars; 129T2/SvEmsJ (129T2), 129S1/SvImJ (129S1), and 129P3/J (129P3)] were the most sensitive strains, but a fourth 129 substrain, 129X1/SvJ (S; dark gray bar), was the most resistant strain initially tested. The C57BL/6J (B; black bar) strain was also sensitive. Other strain abbreviations: AKR, AKR/J; SJL, SJL/J; NZW, NZW/LacJ; cBy, Balb/cByJ; FVB/N, FVB/NJ; MRL, MRL/MpJ; HeB/Fe, C3HeB/FeJ; Balb/c, Balb/cJ; DBA/2, DBA/2J; HeOu, C3H/HeOuJ; C3H, C3H/HeJ; A, A/J; CBA, CBA/J.

 
Assessment of the mouse model: parental and F1 populations.
To gain a better understanding of the B-S model for HALI survival, we increased the sample size of the parental strains and included both males and females. Unexpectedly, after additional S-strain mice were tested over time, the MST decreased to 132 h (n = 180), which placed the S strain in a more intermediate susceptibility category (see Fig. 1), but still surviving significantly longer than the most susceptible strains. B-strain mice were always sensitive or intermediate in sensitivity, with survival times ranging from 64 to 150 h (n = 96). Fewer than 13% (12 of 96) of B mice survived longer than the 132-h mean of the S strain (Fig. 2A). A closer look at the individual survival times of the S mice showed that 33% survived longer than the mean and about one-fourth (41 of 180) died later than the longest-surviving B mouse (150 h). This most resistant subset of S mice had a MST of 192 h. The dichotomy of phenotype suggests that penetrance of the resistance trait is significantly <100%.


Figure 2
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  		Fig. 2. Survival time comparisons of parental and B-S-derived reciprocal F1 crosses. A: comparison of parental S and B strain MST distributions. Each circle denotes a single mouse. No B-strain mouse died after 150 h (dashed line), whereas about 1/4 of S-strain mice died after 150 h. B: box plots of survival time distributions for total parental and reciprocal F1 populations. Individual circles may represent >1 mouse. Solid lines within bars denote median values, and dashed lines represent statistical means of the group. Sample sizes were 180, 96, 53, and 69 for S, B, S.B, and B.S, respectively. C: statistical comparisons of survival times between parental and B-S-derived reciprocal F1 for total mice and for males and females of each group. A solid line represents a significant difference, and a dashed line represents a comparison that did not reach significance. Group comparisons used a Tukey's post hoc comparison test on survival times. Values of P < 0.05 were accepted as significant.

 
To assess the likely mode of inheritance, we first tested B.S F1 offspring for survival time in hyperoxia. Similarly, offspring from the reciprocal F1 cross (i.e., S.B) were also tested to check for a possible parent-of-origin effect, as was suggested with ozone-induced ALI survival (31). Descriptive statistics for the parental and F1 populations are given in Table 1, and their MST distributions are displayed as box plots in Fig. 2B. A significant difference (P = 0.0001) in MSTs was determined for B.S mice [123.3 ± 29.5 (SD) h; n = 69] compared with S.B mice (146.1 ± 36.7 h; n = 53), suggesting that maternal inheritance may control some part of resistance (Fig. 2B). Reciprocal F1 crosses of the P-S strain combination (i.e., P.S vs. S.P) also showed a significant difference in MST (i.e., S.P > P.S), further supporting a maternal inheritance pattern of this trait (data not shown). Thus an S dam yielded more resistant F1 offspring, and B or P dams yielded more sensitive F1 progeny. B.S mice were more resistant than B mice, demonstrating that this F1 hybrid gained dominant resistance alleles from the S strain. Interestingly, S.B mice were even more resistant than the resistant parental S strain (surviving ~14 h longer on average; P = 0.01), indicating that the S strain could gain further resistance with alleles originating from the sensitive B strain (Table 1 and Fig. 2C). On the basis of these findings, we set up breeding pairs of B.S and S.B F1 mice to generate all four possible F2 populations in sufficient numbers, so that each cross had the power to stand alone in subsequent statistical and genetic analyses. Using residual error variances, R/qtlDesign (32) calculated that 190 mice of each F2 cross has 80% power to detect a quantitative trait locus with a threshold logarithm of the odds (LOD) score of 3.0 that explains 10% of the survival time difference between parental strains.


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  		Table 1. Descriptive statistics of control strains and B-S-derived F1 and F2 populations

 
Segregation analysis of F2 populations.
A total of 840 F2 mice (i.e., >190 mice for each of the 4 intercross mating schemes) were generated and continuously exposed to >95% O2. The survival time distribution of the total F2 population was slightly skewed to the left, but a natural log transformation could normalize this distribution curve (data not shown). Descriptive statistics (population sizes, MSTs, and SDs) of the different F2 cohorts are listed in Table 1. The complete data set is presented as total mice (males plus females) and males and females for each F2 cross and for the relevant combined crosses (i.e., F2 groups with a common F1 dam or common F1 sire).

Figure 3 presents comparisons of the F2 populations. MST distributions of the four F2 populations are displayed as box plots in Fig. 3A. All four F2 groups had a similar overall range of survival times. Statistical results of the six pairwise comparisons between the four B-S-derived F2 crosses and the two meaningful combined crosses (i.e., B.S dams vs. S.B dams and B.S sires vs. S.B sires) are presented in Fig. 3B. The survival time comparisons between the F2 cohorts revealed that SB.BS and SB.SB F2 mice (the 2 groups with an S.B dam) did not differ statistically from each other (P = 0.60; dashed line) and BS.BS and BS.SB (2 groups with a B.S dam) also did not differ statistically from each other (P = 0.12; dashed line). However, MSTs of BS.BS F2 mice and BS.SB F2 mice differed significantly from both SB.BS and SB.SB F2 mice (solid lines). SB.BS mice were the most resistant F2 group, whereas BS.SB mice (which are generated from the reciprocal dams and sires, as are SB.BS) were the most sensitive F2 group. The other reciprocal F2 pair (i.e., SB.SB and BS.BS) had intermediate MSTs. Combining F2 groups with a common F1 dam or sire established that groups with an S.B dam (SB.SB + SB.BS) differed significantly (P = 0.0001) from those with a B.S dam (BS.BS + BS.SB) (Fig. 3B).


Figure 3
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  		Fig. 3. Survival time comparisons between B-S-derived F2 populations. A: box plots of survival time distributions for B-S-derived F2 populations. Individual symbols may represent >1 mouse. Solid lines within bars represent median values, and dashed lines represent statistical means. Sample sizes were 213, 221, 197, and 209 for BS.BS, BS.SB, SB.BS, and SB.SB, respectively. B: statistical comparisons of survival time distributions between the 4 F2 crosses. A total of 6 comparisons were made between the 4 F2 groups. In addition, groups with a B.S dam were combined and compared with groups with an S.B dam and groups with a B.S sire were combined and compared with those with an S.B sire. The other combined F2 groups share 1 common F2 cohort and thus reduce to 1 of the original comparisons between the 4 F2 groups. A solid line represents a significant difference, whereas a dashed line represents groups that did not differ. Group comparisons used a Tukey's post hoc comparison test on survival times. Values of P < 0.05 were accepted as significant.

 
Two-way ANOVA with interaction was used to test the between-group effects for cross and sex. This ANOVA indicated no interaction between sex and cross (F3,832 = 1.19, P = 0.31), so the interaction term was removed and main effects of cross and sex were tested separately. Analysis with two-way ANOVA indicated a statistically significant difference among mating groups (F3,832 = 16.70, P < 0.00001). After adjusting for sex, mice from S.B dams survived an average of 17.4 h longer than those from B.S dams (P < 0.0001). Similarly, mice from B.S sires had a 6.4-h higher survival time than those from S.B sires (P = 0.015). After adjusting for cross effect, sex differences were also significant among all F2 groups (F1,835 = 15.45, P < 0.0001). Male mice survived an average of 10.7 h longer than female mice. Altogether, these data reveal that males from an S.B dam are categorically the most resistant B-S F2 mice, and having a B.S sire added additional resistance. Similarly, females from a B.S dam were the most sensitive F2 mice, and having an S.B sire further increased sensitivity. The results provide additional evidence that some part of the overall survival time has a parent-of-origin effect.

Sensitive-to-resistant phenotype ratios.
To further assess a parent-of-origin effect for HALI survival, each mouse was designated as sensitive or resistant (as described in Phenotype designation) and sensitive-to-resistant ratios (S:R) of F2 offspring were determined for males, females, and males plus females within and between all F2 cohorts (Table 2). Because the total F2 data were grouped into quintiles (upper quintile represents the 168 most resistant mice and lower quintile represents the 168 most sensitive mice), the S:R of the total F2 population was necessarily 1.0. For total mice, the S:R ranged more than sixfold between reciprocal F2 groups, with S:R of 2.42 for BS.SB mice and 0.40 for SB.BS mice. Similarly, a sixfold range in S:R was also seen between males (0.33–1.93) and females (0.5–3.1) of these reciprocal F2 crosses. The range of S:R for the other reciprocal F2 pair (BS.BS and SB.SB) was about twofold for total mice, and for males and females separately. Table 3 lists the statistical comparisons of the S:R for each F2 group compared with a null hypothesis value of 1.0 and the S:R for males compared with females within F2 groups.


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  		Table 2. Sensitive-to-resistant ratios of B-S-derived F2 subpopulations in hyperoxia

 

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  		Table 3. Statistical analysis results of sensitive-to-resistant ratios of B-S-derived F2 populations in hyperoxia

 
Within the total F2 population, S:R were opposite for males (0.70) and females (1.48), with males twice as likely as females to be resistant. For each F2 group, males had a S:R that was significantly less (or trended less) than that of females; in most cases, males had S:R nearly half those of females. For example, males from BS.BS (S:R = 0.91) are more than twice as likely as females (S:R = 2.27) to be resistant than sensitive. Similarly, males from S.B dams (S:R = 0.37) are twice as likely to be resistant as sensitive (S:R = 0.76), and about one-fourth as likely to be sensitive as males from B.S dams (S:R = 1.31). These phenotype ratios are consistent with a significant sex effect. Many other comparisons highlight a difference in phenotype based on a common F1 parent. For example, offspring from a B.S dam were nearly twice as likely to be sensitive as resistant (S:R = 1.84), whereas those from an S.B dam were twice as likely to be resistant as sensitive (S:R = 0.52).

Other interesting results emerged when males and females within the two reciprocal F2 groups were compared. BS.BS males have a S:R approaching 1:1 (0.91), but SB.SB males have a S:R of >1:2 (0.41). BS.BS females are twice as likely to be sensitive as resistant (S:R = 2.27), but SB.SB females are equally likely to be sensitive or resistant (S:R = 1.11). For the second reciprocal F2 pair, males and females from BS.SB had at least a 2:1 S:R, whereas males and females from SB.BS had at least a 1:2 S:R. Many additional comparisons of S:R can be made between F2 groups and between sexes within groups, but the results reach similar conclusions and agree with results from analysis of MSTs. Specifically, differences in S:R between F2 groups support a significant sex difference and a parent-of-origin effect on HALI survival time.

Heritability, estimated number of genes involved, and overall mode of inheritance.
Broad sense heritability was 0.56, suggesting that genetics and the environment share equally in the overall phenotype. Narrow sense heritability (h2), the proportion of phenotypic variance that can be attributed to additive genetic variance, was 26% for the entire F2 population. It was higher for males (0.29) than females (0.08) and ranged from negative (–0.19 for BS.SB) to positive (0.23 for BS.BS, 0.26 for SB.SB, and 0.45 for SB.BS) for the different F2 crosses. The minimum estimated number of genes segregating with survival in the total F2 population was less than one. Because at least one of the assumptions for the use of these calculations has been contradicted (i.e., all resistance or sensitivity alleles for the phenotype occur in the same inbred strain), this estimate is not valid. The mode of inheritance of the resistance trait generally followed a maternal pattern for one gene or set of genes (e.g., S.B dams yielded more resistant offspring than B.S dams) but a paternal pattern for another gene or set of genes (e.g., B.S sires had more resistant offspring than S.B sires; Table 1).


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
GRANTS
 REFERENCES
 
Improvement in supportive measures has significantly decreased mortality and morbidity associated with ALI and ARDS over the past two decades, yet the death rate remains unacceptably high. Supplemental O2 and lung-protective strategies are used to combat pulmonary dysfunction. Paradoxically, too much O2 is itself extremely detrimental to the lung. Therefore, O2 therapy for such critically ill patients is a counterbalance between adequate levels for vital blood and tissue oxygenation and its destructive side effects. Given this, we submit that having the ability to use higher levels of O2 for longer periods would afford patients the time to better resolve lung injury, which should lead to decreased ALI-associated morbidity and mortality. Toward this long-term goal, we have established a mouse model to identify genes affecting HALI survival time. Although numerous intermediate phenotypes for ALI could have been chosen for this work, many of which have already been assessed (17, 18, 20–22), survival time was chosen as the end phenotype for these studies, because ALI-associated mortality is the ultimate outcome that must be improved.

To begin to identify important genes affecting the ability to withstand continuous hyperoxia, 18 common inbred strains of mice were screened. The B-S mouse model of HALI was identified for subsequent genetic analysis. Broad-sense heritability was 0.56, suggesting a similar effect on the survival trait from genetic influences and the environment. Narrow-sense heritability differed considerably among the four F2 groups, ranging from negative for BS.SB to 45% for SB.BS and much higher for males than females. By several different formulas, the minimal number of genes segregating with the survival time phenotype was always considerably below one. Because these estimates assume that all sensitive or resistant alleles occur in the same strain, which MSTs and phenotype ratios strongly suggest is not the case, the calculated estimate is unreliable. Further complicating this estimate is the decreased penetrance of the survival trait. This was most evident in the resistant S strain, where only about a fourth of these mice survived longer than the longest surviving mice for the B strain (i.e., >150 h).

Initially, a twofold difference in MSTs was measured between the B and S strains. This difference made the B-S model attractive for these and future genetic studies. However, this difference was identified when only females of each strain were screened. Unexpectedly, as additional mice were phenotyped, the MST of S-strain mice decreased from 182 h (n = 19) to 132 h (n = 180). Nonetheless, the MSTs of the B and S strains differ significantly. A large difference in response between any two strains is desired, but it is not required for a good mouse model of a complex trait. Instead, a good mouse model requires that the genes underlying the phenotype differ between the parental strains and that these genes segregate (i.e., show significant phenotypic differences in their backcross or F2 offspring). In this case, the B-S model meets these requisites. Further helping this model is the existence of at least one resistance gene in the sensitive B strain. Recombination of the resistance genes contributed by both parents can lead to recombinant offspring with survival times greater than either parent. Unfortunately, the smaller difference in MSTs between the B and S strains necessitated significantly larger populations of recombinant mice for genetic analysis. Further complicating subsequent genetic studies is the low penetrance of resistance in the S strain.

Survival times of reciprocal F1 (S.B vs. B.S) mice were consistent with maternal inheritance, with resistance inherited as a dominant trait from the S strain. Whether this mode of inheritance is due to one or more imprinted genes, mitochondrial inheritance, variable expressivity, sex-related differences, or X chromosome linkage was not established here. The complexity of survival time inheritance did not allow an X chromosome effect to be clearly identified, but a major dominant gene on the X chromosome is not supported. Whereas S.B males and S.B females did not differ in MST (a finding that would be expected with a dominant X chromosome-linked gene for resistance), B.S males and B.S females also did not differ (females would be expected to show more resistance, because half would be predicted to have a dominant S allele, assuming random X inactivation). However, S.B males differed from B.S males and S.B females differed from B.S females by >20 h on average. These differences in F1 mice are consistent with imprinting and maternal allelic expression. Interestingly, nearly half of the S.B mice survived longer than any B mouse but only ~16% (~1 of 6) of B.S mice did, suggesting that the parent of origin might also affect penetrance of the resistance trait.

To further assess a parent-of-origin effect, all four F2 crosses were generated and tested. The survival time range of B-S-derived F2 mice was nearly sixfold (2.2–12.6 days), which extends beyond the combined ranges of the two parental strains. This expansion of the phenotype range is consistent with the sensitive B strain carrying one or more resistance genes/alleles or the resistant S strain carrying sensitivity genes/alleles. All F2 groups showed a similar overall range in survival times, but the number of mice at the two extremes of the ranges differed markedly between the groups, resulting in differences in MSTs and S:R among the F2 populations.

Results of segregation analysis demonstrate that HALI survival has a complex mode of inheritance. MSTs for males were more than those for females in control and F2 populations, but not in the reciprocal F1 cohorts (Table 1). A sex difference in ALI deaths has been reported in humans (25), although a sex difference was not found in an earlier report (23). Several animal models have also demonstrated sex differences in lung injury phenotypes (5, 14, 28, 38) and could be related to autosomal (e.g., hormones) or sex chromosome differences or to environmental or other epigenetic factors.

Survival times of the various F2 populations differed significantly within and between most cohorts, and data primarily supported a maternal inheritance of one resistant gene or set of genes and a paternal inheritance of another resistant gene or set of genes. Specifically, F2 crosses with an S.B dam yielded more resistant offspring than those from a B.S dam (SB.BS > BS.BS; SB.SB > BS.SB; S.B dams > B.S dams), and offspring from F2 crosses with a B.S sire were more resistant than those from an S.B sire (BS.BS > BS.SB; SB.BS > SB.SB; B.S sires > S.B sires). These findings directly correlated with the MSTs of the reciprocal F2 groups, in which the SB.BS mice were the most resistant (S.B dam with B.S sire) and BS.SB mice were most sensitive (B.S dam with S.B sire) F2 populations. The second reciprocal F2 pair (BS.BS and SB.SB) had intermediate MSTs and, when compared with MSTs of their common sire or common dam breeding pair (i.e., BS.BS vs. BS.SB and SB.SB vs. SB.BS), demonstrated that an S.B dam imparts more resistance to the overall survival time than does a B.S sire.

Results comparing S:R among and between F2 groups agreed with findings from MST comparisons. Males had lower S:R compared with females, which is in accord with males having higher MSTs than females. F2 groups with S.B dams or B.S sires had lower S:R, whereas B.S dams and S.B sires had higher S:R. Thus, as determined by MSTs, a B.S dam or an S.B sire imparted sensitivity and an S.B dam or a B.S sire imparted resistance in the F2 offspring. Accordingly, S:R were highest for BS.SB females (most sensitive F2 group) and lowest for SB.BS males (most resistant F2 group). Comparisons revealed up to a ninefold difference in S:R for males, females, and total mice, and they highlight the significant sex and cross differences between these F2 groups.

Besides a maternal inheritance pattern (which can include the inheritance of oocyte cytoplasm and mitochondria from the maternal grandmother), the data are also consistent with the strain of origin of the Y chromosome, which derives from the paternal grandfather in an F2 cross (Table 4). The longest-surviving F2 mice were generated from the SB.BS intercross. From MSTs, we found that S.B dams provide the majority of the resistance, but B.S sires confer more resistance than S.B sires. Thus, inheriting the correct resistance alleles from S-strain grandparents leads to the most resistance in F2 offspring. Similarly, BS.SB mice are the most sensitive F2 population; the MST also concurs with sensitivity alleles inherited from B-strain-derived grandparents. Evidence of at least one Y chromosome polymorphism was recently reported to influence susceptibility of both male and female mice to experimental allergic encephalomyelitis, a mouse model of multiple sclerosis (35). In that report, the authors provided evidence for a possible intrauterine positional effect of the pups during gestation and suggested that females may also be affected postnatally as a consequence of the neonate-to-weanling environment. In males, the Y chromosome has been linked to body fat (44) and has also been strongly associated with blood pressure variation (7, 26) and higher cholesterol levels (6), although no genes mapping to the Y chromosome have been specifically identified for these quantitative traits. Nevertheless, the Y chromosome appears to influence susceptibility of these traits, and Y chromosome inheritance is consistent with the HALI MSTs of the B-S-derived F2 populations. Whether male-female differences in HALI survival are due to Y chromosome effects or to environmental or hormonal differences requires additional study.


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  		Table 4. Strain of origin of mitochondria and Y chromosome in B-S F2 subpopulations

 
Collectively, the data presented here identified the B-S mouse model and initiated genetic studies to determine heritability and segregation of HALI survival time. Findings from this mouse model highlight some of the difficulties that could be encountered in performing such analyses in human populations. The survival phenotype is a complex, multigenic trait that demonstrates maternal inheritance, decreased penetrance, and significant sex and cross differences among the F2 groups. Besides dominant resistance genes present in the S strain, one or more dominant resistance genes also exist in the sensitive B strain. These B alleles can impart further resistance to F2 offspring carrying favorable B- and S-strain resistance alleles, or additional sensitivity to those mice with unfavorable allelic combinations. The generated F2 data set, which includes nearly 200 mice (or more) for each of the four F2 crosses of a single mouse model, will be a valuable resource in subsequent genetic studies to begin to identify genes and gene interactions contributing to strain survival differences to HALI.


   GRANTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
REFERENCES
 
This study was funded by the Division and Program in Human Genetics at Cincinnati Children's Hospital Medical Center and by National Heart, Lung, and Blood Institute Grant HL-75562 (D. R. Prows).


   ACKNOWLEDGMENTS
 
The authors thank David Mann, Erin Full, Michelle Horner, Matt Monfils, Shannon Speelman, and Andrea Hogan for technical support and give special thanks to all the dedicated personnel at the Cincinnati Children's Hospital animal facilities. Additional statistical support was provided by Katarzyna (Kasia) Bryc.


   FOOTNOTES
 
Address for reprint requests and other correspondence: D. R. Prows, Children's Hospital Medical Center, 3333 Burnet Ave., Division & Program in Human Genetics, Bldg. R, MLC 7016, Rm. 1464, Cincinnati, OH 45229-3039 (e-mail: daniel.prows{at}cchmc.org).

Article published online before print. See web site for date of publication (http://physiolgenomics.physiology.org).


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 

  1. Adamson IY, Bowden DH, Wyatt JP. Oxygen poisoning in mice. Ultrastructural and surfactant studies during exposure and recovery. Arch Pathol 90: 463–472, 1970.[Web of Science][Medline]
  2. Ahmed MN, Suliman HB, Folz RJ, Nozik-Grayck E, Golson ML, Mason SN, Auten RL. Extracellular superoxide dismutase protects lung development in hyperoxia-exposed newborn mice. Am J Respir Crit Care Med 167: 400–405, 2003.[Abstract/Free Full Text]
  3. Barazzone C, Belin D, Piguet PF, Vassalli JD, Sappino AP. Plasminogen activator inhibitor-1 in acute hyperoxic mouse lung injury. J Clin Invest 98: 2666–2673, 1996.[Web of Science][Medline]
  4. Barazzone C, Horowitz S, Donati YR, Rodriguez I, Piguet PF. Oxygen toxicity in mouse lung: pathways to cell death. Am J Respir Cell Mol Biol 19: 573–581, 1998.[Abstract/Free Full Text]
  5. Caruso JM, Xu DZ, Lu Q, Dayal SD, Deitch EA. The female gender protects against pulmonary injury after trauma hemorrhagic shock. Surg Infect (Larchmt) 2: 231–240, 2001.[CrossRef][Medline]
  6. Charchar FJ, Tomaszewski M, Lacka B, Zakrzewski J, Zukowska-Szczechowska E, Grzeszczak W, Dominiczak AF. Association of the human Y chromosome with cholesterol levels in the general population. Arterioscler Thromb Vasc Biol 24: 308–312, 2004.[Abstract/Free Full Text]
  7. Charchar FJ, Tomaszewski M, Padmanabhan S, Lacka B, Upton MN, Inglis GC, Anderson NH, McConnachie A, Zukowska-Szczechowska E, Grzeszczak W, Connell JM, Watt GC, Dominiczak AF. The Y chromosome effect on blood pressure in two European populations. Hypertension 39: 353–356, 2002.[Abstract/Free Full Text]
  8. Cho HY, Jedlicka AE, Reddy SP, Zhang LY, Kensler TW, Kleeberger SR. Linkage analysis of susceptibility to hyperoxia. Nrf2 is a candidate gene. Am J Respir Cell Mol Biol 26: 42–51, 2002.[Abstract/Free Full Text]
  9. Christofidou-Solomidou M, Scherpereel A, Solomides CC, Muzykantov VR, Machtay M, Albelda SM, DiNubile MJ. Changes in plasma gelsolin concentration during acute oxidant lung injury in mice. Lung 180: 91–104, 2002.[CrossRef][Web of Science][Medline]
  10. Cook DN, Wang S, Wang Y, Howles GP, Whitehead GS, Berman KG, Church TD, Frank BC, Gaspard RM, Yu Y, Quackenbush J, Schwartz DA. Genetic regulation of endotoxin-induced airway disease. Genomics 83: 961–969, 2004.[CrossRef][Web of Science][Medline]
  11. Corne J, Chupp G, Lee CG, Homer RJ, Zhu Z, Chen Q, Ma B, Du Y, Roux F, McArdle J, Waxman AB, Elias JA. IL-13 stimulates vascular endothelial cell growth factor and protects against hyperoxic acute lung injury. J Clin Invest 106: 783–791, 2000.[Web of Science][Medline]
  12. Crapo JD, Barry BE, Foscue HA, Shelburne J. Structural and biochemical changes in rat lungs occurring during exposures to lethal and adaptive doses of oxygen. Am Rev Respir Dis 122: 123–143, 1980.[Web of Science][Medline]
  13. Festing MF, Simpson EM, Davisson MT, Mobraaten LE. Revised nomenclature for strain 129 mice. Mamm Genome 10: 836, 1999.[CrossRef][Web of Science][Medline]
  14. Haston CK, Amos CI, King TM, Travis EL. Inheritance of susceptibility to bleomycin-induced pulmonary fibrosis in the mouse. Cancer Res 56: 2596–2601, 1996.[Abstract/Free Full Text]
  15. Haston CK, Zhou X, Gumbiner-Russo L, Irani R, Dejournett R, Gu X, Weil M, Amos CI, Travis EL. Universal and radiation-specific loci influence murine susceptibility to radiation-induced pulmonary fibrosis. Cancer Res 62: 3782–3788, 2002.[Abstract/Free Full Text]
  16. Ho YS. Transgenic and knockout models for studying the role of lung antioxidant enzymes in defense against hyperoxia. Am J Respir Crit Care Med 166: S51–S56, 2002.[Abstract/Free Full Text]
  17. Holroyd KJ, Eleff SM, Zhang LY, Jakab GJ, Kleeberger SR. Genetic modeling of susceptibility to nitrogen dioxide-induced lung injury in mice. Am J Physiol Lung Cell Mol Physiol 273: L595–L602, 1997.[Abstract/Free Full Text]
  18. Hudak BB, Zhang LY, Kleeberger SR. Inter-strain variation in susceptibility to hyperoxic injury of murine airways. Pharmacogenetics 3: 135–143, 1993.[Web of Science][Medline]
  19. Ikegami M, Jobe AH, Whitsett J, Korfhagen T. Tolerance of SP-A-deficient mice to hyperoxia or exercise. J Appl Physiol 89: 644–648, 2000.[Abstract/Free Full Text]
  20. Kleeberger SR, Levitt RC, Zhang LY. Susceptibility to ozone-induced inflammation. II. Separate loci control responses to acute and subacute exposures. Am J Physiol Lung Cell Mol Physiol 264: L21–L26, 1993.[Abstract/Free Full Text]
  21. Kleeberger SR, Levitt RC, Zhang LY, Longphre M, Harkema J, Jedlicka A, Eleff SM, DiSilvestre D, Holroyd KJ. Linkage analysis of susceptibility to ozone-induced lung inflammation in inbred mice. Nat Genet 17: 475–478, 1997.[CrossRef][Web of Science][Medline]
  22. Kleeberger SR, Reddy S, Zhang LY, Jedlicka AE. Genetic susceptibility to ozone-induced lung hyperpermeability: role of toll-like receptor 4. Am J Respir Cell Mol Biol 22: 620–627, 2000.[Abstract/Free Full Text]
  23. Kollef MH. Acute respiratory failure: a gender-based outcomes analysis. J Gend Specif Med 1: 24–30, 1998.[Medline]
  24. McGrath-Morrow SA, Stahl J. Apoptosis in neonatal murine lung exposed to hyperoxia. Am J Respir Cell Mol Biol 25: 150–155, 2001.[Abstract/Free Full Text]
  25. Moss M, Mannino DM. Race and gender differences in acute respiratory distress syndrome deaths in the United States: an analysis of multiple-cause mortality data (1979–1996). Crit Care Med 30: 1679–1685, 2002.[CrossRef][Web of Science][Medline]
  26. Negrin CD, McBride MW, Carswell HV, Graham D, Carr FJ, Clark JS, Jeffs B, Anderson NH, Macrae IM, Dominiczak AF. Reciprocal consomic strains to evaluate Y chromosome effects. Hypertension 37: 391–397, 2001.[Abstract/Free Full Text]
  27. Ohtsuka Y, Clarke RW, Mitzner W, Brunson K, Jakab GJ, Kleeberger SR. Interstrain variation in murine susceptibility to inhaled acid-coated particles. Am J Physiol Lung Cell Mol Physiol 278: L469–L476, 2000.[Abstract/Free Full Text]
  28. Plopper CG, Buckpitt A, Evans M, Van Winkle L, Fanucchi M, Smiley-Jewell S, Lakritz J, West J, Lawson G, Paige R, Miller L, Hyde D. Factors modulating the epithelial response to toxicants in tracheobronchial airways. Toxicology 160: 173–180, 2001.[CrossRef][Web of Science][Medline]
  29. Prows DR, Daly MJ, Shertzer HG, Leikauf GD. Ozone-induced acute lung injury: genetic analysis of F2 mice generated from A/J and C57BL/6J strains. Am J Physiol Lung Cell Mol Physiol 277: L372–L380, 1999.[Abstract/Free Full Text]
  30. Prows DR, Leikauf GD. Quantitative trait analysis of nickel-induced acute lung injury in mice. Am J Respir Cell Mol Biol 24: 740–746, 2001.[Abstract/Free Full Text]
  31. Prows DR, Shertzer HG, Daly MJ, Sidman CL, Leikauf GD. Genetic analysis of ozone-induced acute lung injury in sensitive and resistant strains of mice. Nat Genet 17: 471–474, 1997.[CrossRef][Web of Science][Medline]
  32. Sen S, Satagopan JM, Broman KW, Churchill GA. R/qtlDesign: inbred line cross experimental design. Mamm Genome 18: 87–93, 2007.[CrossRef][Web of Science][Medline]
  33. Simpson EM, Linder CC, Sargent EE, Davisson MT, Mobraaten LE, Sharp JJ. Genetic variation among 129 substrains and its importance for targeted mutagenesis in mice. Nat Genet 16: 19–27, 1997.[CrossRef][Web of Science][Medline]
  34. Smith LJ. Hyperoxic lung injury: biochemical, cellular, and morphologic characterization in the mouse. J Lab Clin Med 106: 269–278, 1985.[Web of Science][Medline]
  35. Teuscher C, Noubade R, Spach K, McElvany B, Bunn JY, Fillmore PD, Zachary JF, Blankenhorn EP. Evidence that the Y chromosome influences autoimmune disease in male and female mice. Proc Natl Acad Sci USA 103: 8024–8029, 2006.[Abstract/Free Full Text]
  36. Threadgill DW, Yee D, Matin A, Nadeau JH, Magnuson T. Genealogy of the 129 inbred strains: 129/SvJ is a contaminated inbred strain. Mamm Genome 8: 390–393, 1997.[CrossRef][Web of Science][Medline]
  37. Tsan MF, White JE, Caska B, Epstein CJ, Lee CY. Susceptibility of heterozygous MnSOD gene-knockout mice to oxygen toxicity. Am J Respir Cell Mol Biol 19: 114–120, 1998.[Abstract/Free Full Text]
  38. Van Winkle LS, Gunderson AD, Shimizu JA, Baker GL, Brown CD. Gender differences in naphthalene metabolism and naphthalene-induced acute lung injury. Am J Physiol Lung Cell Mol Physiol 282: L1122–L1134, 2002.[Abstract/Free Full Text]
  39. Waheed S, D'Angio CT, Wagner CL, Madtes DK, Finkelstein JN, Paxhia A, Ryan RM. Transforming growth factor alpha (TGF{alpha}) is increased during hyperoxia and fibrosis. Exp Lung Res 28: 361–372, 2002.[CrossRef][Web of Science][Medline]
  40. Wang Y, Phelan SA, Manevich Y, Feinstein SI, Fisher AB. Transgenic mice overexpressing peroxiredoxin 6 show increased resistance to lung injury in hyperoxia. Am J Respir Cell Mol Biol 34: 481–486, 2006.[Abstract/Free Full Text]
  41. Waxman AB, Einarsson O, Seres T, Knickelbein RG, Warshaw JB, Johnston R, Homer RJ, Elias JA. Targeted lung expression of interleukin-11 enhances murine tolerance of 100% oxygen and diminishes hyperoxia-induced DNA fragmentation. J Clin Invest 101: 1970–1982, 1998.[Web of Science][Medline]
  42. Wesselkamper SC, Prows DR, Biswas P, Willeke K, Bingham E, Leikauf GD. Genetic susceptibility to irritant-induced acute lung injury in mice. Am J Physiol Lung Cell Mol Physiol 279: L575–L582, 2000.[Abstract/Free Full Text]
  43. Wright S. Genetic and Biometric Foundations. Chicago, IL: Univ. of Chicago Press, 1968.
  44. York B, Lei K, West DB. Inherited non-autosomal effects on body fat in F2 mice derived from an AKR/J x SWR/J cross. Mamm Genome 8: 726–730, 1997.[CrossRef][Web of Science][Medline]
  45. Zhang X, Shan P, Qureshi S, Homer R, Medzhitov R, Noble PW, Lee PJ. Cutting edge: TLR4 deficiency confers susceptibility to lethal oxidant lung injury. J Immunol 175: 4834–4838, 2005.[Abstract/Free Full Text]



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