Androgen therapy induces muscle protein anabolism in older women.

CONTEXT: Normal healthy men and women undergo a gradual loss of skeletal muscle mass and strength with advancing age. While androgens are protein anabolic in older men, the metabolic effects in older women are poorly understood. OBJECTIVE AND DESIGN: The objective of this study was to determine whether oral administration of a synthetic derivative of testosterone [oxandrolone, Oxandrin (OX)] (7.5 mg orally twice daily for 14 d) to five older women (age, 65 +/- 2 yr) would enhance skeletal muscle anabolic biomarkers including mixed muscle fractional synthetic rate (FSR), net phenylalanine balance, androgen receptor, and IGF-I protein expression at d 0, 5, and 14 of treatment. As a positive control, seven older men were examined after 14 d of OX (10 mg orally twice daily). SETTING: The study was performed at the General Clinical Research Center. RESULTS: Fourteen days of OX significantly increased skeletal muscle FSR in older women (d 0, 0.073 +/- 0.006 vs. d 5, 0.092 +/- 0.006 vs. d 14, 0.115 +/- 0.007%/h) (P < 0.05, d 0 vs. d 14). Conversely, OX stimulated FSR in older men after only 5 d (d 0, 0.061 +/- 0.003 vs. d 5, 0.101 +/- 0.01 vs. d 14, 0.084 +/- 0.01%/h) (P < 0.05, d 0 vs. d 5). Androgen receptor expression was significantly increased in older men by d 14, but had not increased in older women. No change was noted in IGF-I expression in either group. We conclude that the skeletal muscle of older women and men responds to androgen administration, although the time course of anabolism appears to be gender specific.

Nickel potentiates the genotoxic effect of benzo[a]pyrene in Chinese hamster lung V79 cells.

The modulating effect of acute exposure to NiCl2 on the induction of chromosome aberrations by a model carcinogen, benzo[a]pyrene (B[a]P), was examined in Chinese hamster V79 lung cells. At concentrations up to 20 microg/ml (84.2 microM), NiCl2 did not significantly increase the frequency of chromosome aberrations in V79 cells when the cells were exposed concomitantly to 0.5 microg/ml B[a]P. Addition of the S15 liver microsomal fraction together with the B[a]P did not alter the results. Addition of NiCl2 2 hr before treatment of cells with 0.5 microg/ml B[a]P also did not result in a significant elevation of the frequency of chromosome aberrations, even at NiCl2 concentrations as high as 20 microg/ml. Contrasting sharply with these findings, when V79 cells were treated with NiCl2 immediately after B[a]P exposure, a significant increase in the frequency of chromosome damage was observed at NiCl2 concentrations as low as 5 microg/ml (21.1 microM). NiCl2-mediated enhancement of chromosome damage was also observed when V79 cells were exposed to the reactive B[a]P intermediate, benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide (BPDE). In the BPDE-treated cells, the level of NiCl2-mediated enhancement was similar to that observed with the tumor promoter 12-o-tetradecanoylphorbol-13-acetate (TPA, 100 ng/ml). These results are consistent with the view that the effect of nickel (II) on B[a]P-induced genetic damage is dependent on the relative times of exposure to Ni2+ and B[a]P. NiCl2 did not enhance the frequency of chromosome aberrations induced by Chromium (VI), regardless of the order of addition of the chemicals to the V79 cells. These results suggest that nickel may act as a promoter of chemically-induced genetic damage through induction of error-prone repair.

Identification of factors contributing to hepatomegaly in severely burned children.

Hepatomegaly is a common postmortem observation in severely burned children, with the liver often tripling in size when compared with normal livers for age, weight, and sex. Lesions identified at autopsy include deposition of large and small fat droplets in the hepatocyte, congestion, centrilobular necrosis, and cholestasis. The present study was designed to identify the primary causes of hepatomegaly in severely burned children postmortem. For this purpose, 41 autopsies were reviewed and, when available, blood and tissue samples were studied. Histopathologic findings showed that large intrahepatocytic fat droplets within hepatocytes and cholestasis were important contributors to hepatomegaly. Liver density and wet/dry weight ratios significantly decreased with increasing liver size. Hepatocyte volume increased with increasing liver size (P < 0.001) as did total fat content (P < 0.001). The liver enzymes, alanine aminotransferase and aspartate aminotransferase, remained normal except within 5 to 10 days of injury and 5 to 10 days of death. Triglycerides made up 4% to 70% of the total fat, with the percentage of triglycerides increasing with the severity of hepatomegaly. Saturated fatty acids represented about 85% of the total fatty acids in normal-sized livers, whereas in the largest livers (400% of predicted), only 25% of the fatty acids were saturated. This study provides evidence that 85% to 90% of the hepatomegaly observed in severely burned children postmortem is associated with hepatocyte enlargement, which includes up to 19% intracellular fat. Increases in extracellular protein, intracellular glycogen, and fluid accumulation may make a minor contribution to postburn hepatomegaly.

Variability in human sensitivity to 1,3-butadiene: influence of polymorphisms in the 5'-flanking region of the microsomal epoxide hydrolase gene (EPHX1).

The carcinogenic effects of 1,3-butadiene (BD), a mutagenic chemical widely used in the manufacture of synthetic rubber, are likely initiated through its epoxide metabolites. In humans, these epoxides are detoxified predominantly by hydrolysis, a reaction mediated by the microsomal epoxide hydrolase (mEH; EPHX1) enzyme. It appears reasonable to hypothesize that BD-exposed individuals possessing lower mEH detoxification capacity may have elevated risk of adverse health effects. The interindividual levels of mEH enzymatic activity vary considerably, and polymorphisms in the mEH gene may contribute to this variability. In addition to the well-studied coding region polymorphisms encoding Tyr113His and His139Arg substitutions, seven other polymorphic sites in the 5'-flanking region of the mEH gene have been reported. These polymorphisms appear to differentially affect mEH gene transcriptional activities. The 5'-flanking region polymorphisms exist in two linkages, the -200 linkage (-200C/T, -259C/T, -290T/G) and the -600 linkage (-362A/G, -613T/C, -699T/C), whereas the -399T/C polymorphism exists as an independent site. Because these polymorphisms may affect total mEH enzymatic activity, we hypothesized that they influence the mutagenic response associated with occupational exposure to BD. We genotyped the 5'-region of the mEH gene in 49 non-smoking workers from two styrene-butadiene rubber facilities in southeast Texas and evaluated the linkage patterns against results obtained from an autoradiographic HPRT mutant lymphocyte assay, used as a biomarker of genotoxic effect. In the study population, 67% were exposed to low BD levels, <150 parts per billion, and 33% were exposed to >150 ppb. We used the observed HPRT mutant (variant) frequency (VF) in the studied population and a 4-way first-order interaction statistical model to estimate parameters that describe the influence of exposure, genotypes and the interaction between the two on the HPRT VF in the target population. The background (baseline) VF, defined as the VF (x 10(-6)) +/- S.E.M. at low levels of BD exposure (<150 ppb) where all the genotypes under study are homozygous wild-type, was estimated to be 4.02 +/- 1.32. Exposure to >150 ppb of BD alone resulted in an estimated increase in VF of 3.42 +/- 2.47 above the baseline level. Inheritance of the variant ATT allele in the -600 linkages resulted in an estimated increase in VF of 3.39 +/- 1.67 above the baseline level. When the interaction between BD exposure and the ATT allele in the -600 linkage group was considered, a statistically significant positive interaction was observed, with an estimated increase in the VF of 10.89 +/- 2.16 (95% CI = 6.56-15.20; p = 0.0027) above baseline. These new data confirm and extend our previous findings that sensitivity to the genotoxic effects of BD is inversely correlated with predicted mEH activity.

Diarrhea in severely burned children.

BACKGROUND: Diarrhea is a common problem in critically ill patients. Our patients are fed a high-carbohydrate enteral formula. We hypothesized that diarrhea in our patients may be related to the osmotic effects of unabsorbed carbohydrate in the small intestine and colon. METHODS: We studied 19 patients, 3 months to 17 years, with burns >40% total body surface area. Each subject was studied weekly for up to 4 weeks postburn. Breath H2 concentration was measured. For the 24-hour period before the breath H2 measurement, the enteral carbohydrate intake, stool volume, and total enteral fluid volume were recorded. At each of several weekly intervals for each subject, the times when stool volume and enteral carbohydrate intake were each maximal were noted. RESULTS: Maximal stool volume ranged from 12 to 69 mL/kg/d. At the time point of maximal carbohydrate intake, diarrhea (stool volume >10 mL/kg/d) occurred in 18 of 19 patients, and maximal stool volume occurred in 10 of 19. Breath H2 concentration (ppm/5% CO2; mean +/- SEM) was 5.5 +/- 3.5 at the time of maximal carbohydrate intake, and was 25 +/- 20 at maximal stool volume. There were no correlations among breath H2 concentration, stool volume, enteral fluid intake, and enteral carbohydrate intake. CONCLUSIONS: Almost all the subjects had diarrhea over several weeks postburn. The lack of correlation of either carbohydrate intake or breath H2 with stool volume suggests that diarrhea in these patients may be caused by factors other than carbohydrate malabsorption. These data do not support altering nutrition support because of watery diarrhea.

Biomarkers in Czech workers exposed to 1,3-butadiene: a transitional epidemiologic study.

A multiinstitutional, transitional epidemiologic study was conducted with a worker population in the Czech Republic to evaluate the utility of a continuum of non-disease biological responses as biomarkers of exposure to 1,3-butadiene (BD)* in an industrial setting. The study site included two BD facilities in the Czech Republic. Institutions that collaborated in the study were the University of Vermont (Burlington, Vermont, USA); the Laboratory of Genetic Ecotoxicology (Prague, the Czech Republic); Shell International Chemicals, BV (Amsterdam, The Netherlands); the University of North Carolina at Chapel Hill (Chapel Hill, North Carolina, USA); University of Texas Medical Branch at Galveston (Galveston, Texas, USA); Leiden University (Leiden, The Netherlands); and the Health and Safety Laboratory (Sheffield, United Kingdom). Male volunteer workers (83) participated in the study: 24 were engaged in BD monomer production, 34 in polymerization activities, and 25 plant administrative workers served as unexposed control subjects. The BD concentrations experienced by each exposed worker were measured by personal monitor on approximately ten separate occasions for 8-hour workshifts over a 60-day exposure assessment period before biological samples were collected. Coexposures to styrene, benzene, and toluene were also measured. The administrative control workers were considered to be a homogeneous, unexposed group for whom a series of 28 random BD measurements were taken during the exposure assessment period. Questionnaires were administered in Czech to all participants. At the end of the exposure assessment period, blood and urine samples were collected at the plant; samples were. fractionated, cryopreserved, and kept frozen in Prague until they were shipped to the appropriate laboratories for specific biomarker analysis. The following biomarkers were analyzed: * polymorphisms in genes involved in BD metabolism (Prague and Burlington); * urinary concentrations of 1-hydroxy-2-(N-acetylcysteinyl)-3-butene and 2-hydroxy-1-(N-acetylcysteinyl)-3-butene (M2 [refers to an isomeric mixture of both forms]) (Amsterdam); * urinary concentrations of 1,2-dihydroxy-4-(N-acetylcysteinyl)-butane (M1) (Amsterdam); * concentrations of the hemoglobin (Hb) adducts N-(1-[hydroxymethyl]-2-propenyl)valine and N-(2-hydroxy-3-butenyl)valine (HBVal [refers to an isomeric mixture of both forms]) (Amsterdam); * concentrations of the Hb adduct N-(2,3,4-trihydroxybutyl)valine (THBVal) (Chapel Hill); * T cell mutations in the hypoxanthine phosphoribosyltransferase (HPRT) gene (autoradiographic assay in Galveston with slide review in Burlington; cloning assay in Leiden with mutational spectra determined in Burlington); and * chromosomal aberrations by the conventional method and by fluorescence in situ hybridization [FISH]), and cytogenetic changes (sister chromatid exchanges [SCEs] (Prague). All assay analysts were blinded to worker and sample identity and remained so until all work in that laboratory had been completed and reported. Assay results were sent to the Biometry Facility in Burlington for statistical analyses. Analysis of questionnaire data revealed that the three exposure groups were balanced with respect to age and years of residence in the district, but the control group had significantly more education than the other two groups and included fewer smokers. Group average BD exposures were 0.023 mg/m3 (0.010 ppm) for the control group, 0.642 mg/m3 (0.290 ppm) for the monomer group, and 1.794 mg/m3 (0.812 ppm) for the polymer group; exposure levels showed considerable variability between and within individuals. Styrene exposures were significantly higher in the polymer group than in the other two groups. We found no statistically significant differences in the distributions of metabolic genotypes over the three exposure groups; genotype frequencies were consistent with those previously reported for this ethnic and national population. Although some specific genotypes were associated with quantitative differences in urinary metabolite concentrations or Hb adduct dose-response characteristics, none indicated a heightened susceptibility to BD. Concentrations of both the M2 and M1 urinary metabolites and both the HBVal and THBVal Hb adducts were significantly correlated with group and individual mean BD exposure levels; the Hb adducts were more strongly correlated than the urinary metabolites. By contrast, no significant relations were observed between BD exposures and HPRT gene mutations (whether determined by the auto-radiographic or the cloning method) or any of the cytogenetic biomarkers (whether determined by the conventional method or FISH analysis). Neither the mutational nor the cytogenetic responses showed any association with genotypes. The molecular spectrum of HPRT mutations in BD-exposed workers showed a high frequency of deletions; but the same result was found in the unexposed control subjects, which suggests that these were not due to BD exposure. This lack of association between BD exposures and genetic effects persisted even when control subjects were excluded from the analyses or when we conducted regression analyses of individual workers exposed to different levels of BD.

Age-associated changes in SAPK/JNK and p38 MAPK signaling in response to the generation of ROS by 3-nitropropionic acid.

Mitochondrial dysfunction has been identified as a major source of oxidative stress in aged tissues. In this study we asked whether activities of components of the SAPK/JNK and p38 MAPK stress response signaling pathways are indicative of oxidative stress in aged mouse livers and whether these pathways are responsive to oxidative stress generated by 3-nitropropionic acid (3-NPA), an inhibitor of complex II (succinic dehydrogenase). We asked whether (a) aging affects the basal activity of the SAPK/JNK stress signaling pathway; (b) specific isoforms of JNK, i.e. 46 or 54 kDa JNKs are activated by 3-NPA; (c) aging affects the response of this signaling pathway to 3-NPA; (d) there is a cross pathway activation of JNK or p38 MAPK by upstream activators. Our studies have shown that although their protein pool levels are not altered, the basal JNK activities using c-Jun as substrate is elevated. Furthermore, in aged livers, JNK activity is induced to a greater extent and takes longer to recover from 3-NPA treatment. The activities of the upstream activators of JNKs, MAP kinase kinase (MKK) 4 and 7, are also elevated in livers of aged C57BL/6 male mice. These activator kinases, which are induced (phosphorylated) by 3-NPA in young livers, are not inducible by this inhibitor in aged livers. In fact, these proteins are highly phosphorylated in the control aged livers and are dephosphorylated in response to 3-NPA. Finally, we demonstrate for the first time that MKK7 serves as an upstream activator of p38 MAPK and that MKK3 and MKK6 activates 54 kDa JNK2 in aged liver. Our studies suggest that failure to respond to 3-NPA may be indicative of the susceptibility of aged tissue to oxidative stress, supporting our hypothesis that aged tissues (especially liver) develop a state of chronic stress even in the absence of a challenge.

Prediction of mortality from catastrophic burns in children.

BACKGROUND: We previously developed a model to predict survival in massive paediatric burns (>80% total body surface area [TBSA]). This model included not only demographic variables, but also variables obtained throughout the hospital course. We aimed to prospectively validate our model for accuracy of outcome prediction. METHODS: We admitted 33 paediatric burn patients with burns greater than 80% TBSA. We recorded age, burn size, inhalation injury, resuscitation, packed-cell volume at admission, base deficit, serum osmolarity, sepsis, inotropic support, platelet count, creatinine, and ventilator dependency. We entered these data into our previous models. RESULTS: 20 male and 13 female children with mean age 7.6 (SD 1) years with TBSA burns of 88% (SD 1; full thickness 86% [SD 1]) were admitted. Mortality was 39.4% (13 of 30). When all variables were integrated into our final model, we predicted outcome with 97% accuracy. When we used a model based only on demographic characteristics of age, burn size, and presence of inhalation injury, outcome was correctly predicted in only 51% of patients. CONCLUSION: We show prospectively that mortality in severely burned children can be reliably estimated at a burn centre, and that outcome cannot be reliably predicted on the basis of demographic and injury characteristics alone. These data suggest that all severely burned children should be given a course of treatment before consideration of treatment futility.