Oxidative Stress in Youth and Adolescents With Elevated Body Mass Index Exposed to Secondhand Smoke.

INTRODUCTION: Our objective was to investigate the relationships between secondhand smoke (SHS) exposure and oxidative stress in a group of youth and adolescents with elevated body mass index. METHODS: Participants in this cross sectional study were healthy nonsmoking youth and adolescents ages 9 to 18 years old. Three-quarters of the participants were either overweight or obese. SHS exposure was determined by survey and hair nicotine level. Markers of oxidation were total antioxidant capacity and protein malondialdehyde adducts (MDA). RESULTS: Ninety subjects were studied; adequate hair samples were available for 86. The mean hair nicotine level was 0.75ng/mg, the median was 0.58ng/mg and the range was 0.09-2.88ng/mg. There was a significant relationship between MDA and the three survey questions regarding smoke exposure ([mother smokes, r = 0.29, P = .006], [smoker lives in the home, r = 0.31, P = .004], and [number of smokers in the home, r = 0.36, P = .002]). There was a significant positive relationship between log-hair nicotine and MDA (Pearson r = 0.233, P = .031), which remained significant after controlling for age, sex, race, and method of insurance. No relationship was found between log-hair nicotine and total antioxidant capacity. However, there was a significant relationship between number of smokers in the home (r = 0.24, P = .042) and total antioxidant capacity. CONCLUSIONS: We have demonstrated a significant positive relationship hair nicotine level and MDA in a group of youth with a high proportion of overweight/obese subjects. IMPLICATIONS: We have shown a significant relationship between objectively measured SHS exposure and one marker of oxidative stress in a sample of youth and adolescents with a high proportion of overweight/obese subjects, and who were nonsmokers with relatively low tobacco exposure. This finding remains significant after controlling for age, sex, race, and type of medical insurance. Since the cardiovascular effects of SHS exposure are related to oxidative stress, this finding adds to our knowledge that the sequence of deleterious effects of tobacco exposure on the cardiovascular system begins long before clinical disease is evident.

Lung development alterations in newborn mice after recovery from exposure to sublethal hyperoxia.

Exposure of newborn mice to hyperoxia arrests lung development, with resultant pathological characteristics similar to bronchopulmonary dysplasia in infants born prematurely. We tested the hypothesis that aberrations in lung development caused by 14 days of sublethal hyperoxia would be reversed during 14 days of recovery to room air (RA) when the concentration of oxygen exposure was weaned gradually. Newborn FVB mice were exposed to 85% oxygen or RA for 14 days. Weaning from hyperoxia was by either transfer directly into RA or a decrease in the concentration of oxygen by 10% per days. At 28 days, pups were euthanized, and the lungs were inflation fixed and assessed. At postnatal day 28, lungs of mice weaned abruptly from hyperoxia had fewer (6 ± 0.6 versus 10 ± 0.7; P < 0.001) alveoli per high-powered field and larger alveoli (4050 ± 207 versus 2305 ± 182 µm(2)) than animals weaned gradually; both hyperoxia-exposed groups were different from lungs obtained from air-breathing controls (20 ± 0.5 alveoli per high-powered field; P < 0.001). The results are consistent with the absence of catch-up alveolarization in this model and indicate that the long-term consequences of early exposures to hyperoxia merit closer examination. The effects of abrupt weaning to RA observed further suggest that weaning should be considered in experimental models of newborn exposure to hyperoxia.

Cellular strain amplifies LPS-induced stress signaling in immature enterocytes: potential implications for preterm infant NCPAP.

BACKGROUND: Recent clinical observations of increased necrotizing enterocolitis (NEC) incidence in some nasal continuous positive airway pressure (NCPAP) patients raise concerns about whether the related abdominal distension is benign or contributes to NEC. We tested the hypothesis that mechanical strain causes an exaggerated enterocyte inflammatory response and decreased enterocyte growth and proliferation in the absence and presence of lipopolysaccharide (LPS). METHODS: First we used a confluent enterocyte (IEC-6) monolayer to investigate effects of strain on inflammatory cytokine production and Toll-like receptor 4 (TLR-4) gene expression. Then we used a low seeding density to measure cell growth and proliferation. Ten percent mechanical strain was applied. RESULTS: Significant increases in interleukin (IL)-8 and in IL-6 were observed after 8 and 24 h of cellular strain, respectively, and maintained throughout the study. TLR-4 expression was increased at 48 h. Mechanical strain led to slower proliferation and division whereas LPS alone had minimal effects. The responses of LPS and strain were supra-additive, suggesting synergistic cellular effects. CONCLUSION: We speculate intestinal distension associated with the use of NCPAP, especially in the presence of abnormal gut colonization, may result in increased inflammatory cytokine production and be a contributing factor to neonatal intestinal morbidities.

LPS-binding protein enables intestinal epithelial restitution despite LPS exposure.

OBJECTIVES: Intestinal epithelial restitution is the first part in the process of mucosal repair after injury in the intestine. Integrity of the intestinal mucosal barrier is important as a first line of defense against bacteria and endotoxin. Necrotizing enterocolitis (NEC) is a major cause of morbidity and mortality in extremely-low-birth-weight infants, but its mechanisms are not well defined. Abnormal bacterial colonization, immature barrier function, innate immunity activation, and inflammation likely play a role. Lipopolysaccharide (LPS)-binding protein (LBP) is secreted by enterocytes in response to inflammatory stimuli and has concentration-dependent effects. At basal concentrations, LBP stimulates the inflammatory response by presenting LPS to its receptor; however, at high concentrations, LBP is able to neutralize LPS and prevent an exaggerated inflammatory response. We sought to determine how LBP would affect wound healing in an in vitro model of intestinal cell restitution and protect against intestinal injury in a rodent model of NEC. METHODS: Immature intestinal epithelial cells (IEC-6) were seeded in poly-L-lysine-coated 8-chamber slides and grown to confluence. A 500-µm wound was created using a cell scraper mounted on the microscope to achieve uniform wounding. Media was replaced with media containing LPS ± LBP. Slide wells were imaged after 0, 8, and 24 hours and then fixed. Cellular restitution was evaluated via digital images captured on an inverted microscope and wound closure was determined by automated analysis. Toll-like receptor 4 (TLR4) was determined by reverse transcriptase-polymerase chain reaction after RNA isolation from wounded cells 24 hours after treatment. RESULTS: LPS alone attenuated wound healing in immature intestinal epithelium. This attenuation is reversed by 24 hours with increasing concentrations of LBP so that wound healing is equivalent to control (P < 0.001). TLR4 was increased with LPS alone but levels returned to that of control after addition of LBP in the higher concentrations. LBP had no effect on the development of intestinal injury when given during our rodent model of NEC. Abnormal bacterial colonization and activation of innate immunity by LPS are likely involved in the pathogenesis of NEC.The attenuation of wound healing was reversed when LBP was added to LPS but only in the higher concentrations. At these same concentrations of LBP, TLR4 was decreased to that of control. CONCLUSIONS: These results indicate that LBP may be a novel therapeutic strategy to facilitate wound healing after the acute phase of NEC and other forms of intestinal injury.

Poly(ADP-ribose) polymerase-1: a novel therapeutic target in necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of infancy, afflicting 11% of infants born 22-28 wk GA. Both inflammation and oxidation may be involved in NEC pathogenesis through reactive nitrogen species production, protein oxidation, and DNA damage. Poly(ADP-ribose) polymerase-1 (PARP-1) is a critical enzyme activated to facilitate DNA repair using nicotinamide adenine dinucleotide (NAD+) as a substrate. However, in the presence of severe oxidative stress and DNA damage, PARP-1 overactivation may ensue, depleting cells of NAD+ and ATP, killing them by metabolic catastrophe. Here, we tested the hypothesis that NO dysregulation in intestinal epithelial cells during NEC leads to marked PARP-1 expression and that administration of a PARP-1 inhibitor (nicotinamide) attenuates intestinal injury in a newborn rat model of NEC. In this model, 56% of control pups developed NEC (any stage) versus 14% of pups receiving nicotinamide. Forty-four percent of control pups developed high-grade NEC (grades 3-4), whereas only 7% of pups receiving nicotinamide developed high-grade NEC. Nicotinamide treatment protects pups against intestinal injury incurred in the newborn rat NEC model. We speculate that PARP-1 overactivation in NEC may drive mucosal cell death in this disease and that PARP-1 may be a novel therapeutic target in NEC.

Vasoprotective endothelial effects of a standardized grape product in humans.

The pathogenesis of coronary lesion development is a multi-factorial process involving a number of different cell types and covariates, and injury and dysfunction of the vascular endothelium is an important marker and likely participant in the initiation and/or progression of most forms of heart disease. In addition to chronic dysfunction of endothelial responses in patients with established heart disease, there is evidence that 'acute insults' can cause measurable dysfunction in vascular response in humans (drug toxicities, hypoxia, high fat meal). Such repeated acute insults may contribute to disease risk in otherwise healthy individuals or promote disease progression in established patients. Consumption of grape products, especially wine, has been linked to lower cardiovascular risk but the vascular endothelial effects of grape products in healthy normal subjects, in the absence of ethanol, have not been evaluated. We therefore tested the hypotheses that 1) a standardized product derived from fresh grapes (GP, acute and chronic consumption) improves endothelial performance in healthy normal young subjects, and 2) that concomitant grape consumption affects the 'acute endothelial insult' caused by a single standardized high fat meal (HF). Acute consumption of GP equivalent to 1.25 cups of fresh grapes caused significant improvement in brachial artery flow mediated dilation (FMD) within 3 h of consumption, when compared to control consumption of sugar solution (p<0.05). No acute changes in heart rate, hemodynamics, or lipid profiles were observed. When this 'dose' was then consumed twice daily for 3 weeks FMD was further improved and total antioxidant capacity in plasma was slightly increased (p<0.05), with no change in heart rate, hemodynamics, or lipid profiles. A single HF meal (900 cal, 49 g total fat) caused a 50% reduction in FMD response when consumed alone, and this effect coincided with increased blood triglyceride levels within 3 h post-consumption. In contrast the concomitant consumption of GP with the HF meal completely prevented this HF-induced vascular endothelial dysfunction (p<0.05), but had no effect on rising triglycerides. These data demonstrate that a modest intake of fresh grapes can have acute favorable effects on vascular endothelial function in normal healthy subjects, that chronic intake can further improve performance and concomitant intake can blunt the 'acute insult' to endothelium caused by a typical western HF meal. This effect is likely to be related to antioxidant effects at the endothelium, rather than changes in blood lipids. These data support epidemiological data of the health benefits of grapes, and demonstrate that 'favorable' food consumption can apparently reduce some toxicities induced by 'unfavorable' food consumption.

Prenatal lipopolysaccharide increases postnatal intestinal injury in a rat model of necrotizing enterocolitis.

BACKGROUND: An increased incidence of necrotizing enterocolitis (NEC) has been noted in infants who are born to mothers with chorioamnionitis. HYPOTHESIS: Our objective was to test the hypothesis that newborn rat pups born to mothers exposed to prenatal lipopolysaccharide during pregnancy would be more susceptible to intestinal injury in a rat model of NEC and that the increased intestinal injury is mediated by dysregulation of inducible nitric oxide synthase. METHODS: Time-dated pregnant Sprague-Dawley dams were given an intraperitoneal injection of either 2 mg/kg of lipopolysaccharide or vehicle. Rat pups from each group of dams were delivered at term and placed in a rat NEC model. A subset of pups was given either vehicle or aminoguanidine. Intestines were harvested and graded for degree of intestinal injury. RESULTS: Maternal prenatal lipopolysaccharide exposure increased the frequency and severity of intestinal injury in the neonatal rat NEC model. Treatment with aminoguanidine significantly decreased plasma nitric oxide levels. Additionally, aminoguanidine significantly decreased intestinal injury. CONCLUSIONS: Intestinal injury observed may be mediated via nitric oxide synthase dysregulation.

Activation of Akt and mTOR in CD34+/K15+ keratinocyte stem cells and skin tumors during multi-stage mouse skin carcinogenesis.

BACKGROUND: The goal of the present studies was to localize two proteins known to be involved in regulation of cell proliferation and survival in specific cell populations in normal SENCAR mouse skin and during multi-stage skin carcinogenesis. The proteins evaluated included activated Akt, as defined by phosphorylation of Akt at Serine-473 (pAkt) and mammalian target of rapamycin (pmTOR), defined by phosphorylation of mTOR at Serine-2448 (pmTOR). The cell populations examined included mouse keratinocyte stem cells (KSCs) within hair follicles and preneoplastic papilloma cells. MATERIALS AND METHODS: Immunochemical staining analysis as well as triple color immunofluorescence in combination with confocal microscopy were used to evaluate the presence of activated Akt and mammalian target of rapamycin (mTOR) in KSCs within the bulge niche of hair follicles, as identified by expression of the specific markers of mouse KSCs, CD34 and cytokeratin 15 (K15). Western blot analysis was used to examine CD34 and K15 protein levels in dorsal skin isolated from SENCAR mice during multi-stage skin carcinogenesis. RESULTS: CD34+/K15+ KSCs were located only in the outer root sheath (ORS) of a specific niche within hair follicles defined as "the bulge". The location of CD34+/K15+ KSCs remained restricted to the bulge region throughout the 22-week time-period examined during which pre-malignant papillomas developed and rapidly expanded. There was a significant decrease in K15 protein levels at 24 h and 15 weeks in dorsal skin treated with DMBA/TPA compared to CD34 protein levels. CD34+ cells within the numerous hair follicles in hyperplastic skin were found to undergo proliferation during the process of multi-stage skin carcinogenesis based on their staining with antibodies directed against proliferating cell nuclear antigen (PCNA). While pAkt was present within the bulge region of hair follicles, pmTOR was present in cells in the ORS of the bulge region as well as the upper infundibulum of hair follicles in dorsal skin treated with acetone. Within papillomas tissues isolated at 15 weeks following DMBA/TPA treatment, pAkt was localized to suprabasal cells with nominal staining of pAkt in the basal cell layer. There were fewer cells within the basal cell layer that contained pmTOR, in addition to the presence of pmTOR in suprabasal cells within papillomas. CONCLUSION: These results provide first time evidence for pAkt and pmTOR in CD34+/K15+ KSCs localized to the outer root sheath niche of the bulge region of mouse hair follicles. Taken together, the present observations suggest that pAkt and pmTOR may allow this cell population to evade terminal differentiation and to persist for long periods of time in their specific niche. Strategies that target pAkt and pmTOR may deplete both cells within the CD34+/K]5+ KSCs compartment, as well as impacting the survival of nonproliferating suprabasal cells within pre-malignant papillomas.

Effects of prenatal lipopolysaccharide exposure on epithelial development and function in newborn rat intestine.

BACKGROUND: Maternal infection during pregnancy is associated with several neonatal morbidities, including periventricular leukomalacia and lung maldevelopment and injury. OBJECTIVE: To test the hypothesis that responses to prenatal maternal exposure to lipopolysaccharide (LPS) alter intestinal epithelial development and function in newborn rats. DESIGN/METHODS: Timed-pregnancy female Sprague-Dawley rats were administered either 2 mg LPS or an equal volume of isotonic saline by intraperitoneal injection at E16 and allowed to deliver naturally. Pups were weighed and then killed at days of life (DOL) 0, 3, 7 and 14. Morphometric parameters were measured on standard hematoxylin and eosin-stained sections using ImagePro software. Immunohistochemistry was performed with antibody specific for inducible nitric oxide synthase (iNOS) and 3-nitrotyrosine on distal ileal intestinal samples analyzed at each time point. Optical density was determined and quantified for site-specific regions of intestinal sections. On DOL 14, in vivo mucosal permeability was measured by feeding rats fluorescein isothiocyanate (FITC) via orogastric tube; and then serum FITC was measured. RESULTS: There were no significant differences in pup weights. Mucosal thicknesses were significantly less in the distal ileum from pups born to LPS-exposed dams on DOL 0, 3 and 7 (P < 0.001). On DOL 0, iNOS protein concentrations in the prenatal LPS treatment group were significantly greater than iNOS protein concentrations in the distal villus (P < 0.001), proximal villus/crypts (P < 0.01), submucosa (P < 0.001) and muscularis (P < 0.01) in the distal small intestine of the control group. On DOL 3, 7 and 14, significant differences were observed in iNOS protein concentrations in the distal villus and submucosal regions between groups (P < 0.001). On DOL 0, 3, 7 and 14, 3-nitrotyrosine immunostaining was significantly elevated in the prenatal LPS-exposed pups in the distal villus on (P < 0.001) as well as in the submucosa on DOL 3 (P < 0.001). Serum FITC measurement was significantly greater in prenatal LPS exposure group at DOL 14 (P < 0.001). CONCLUSIONS: Maternal exposure to LPS during pregnancy alters intestinal growth and regulation of iNOS in the newborn rat intestine.

Cardiomyopathy in a murine model of AIDS: evidence of reactive nitrogen species and corroboration in human HIV/AIDS cardiac tissues.

OBJECTIVE: Cardiomyopathy and other vascular complications are now recognized as significant components of HIV/AIDS pathogenesis. Although the mechanisms involved in cardiomyopathy are poorly defined, a role for direct retroviral action and/or focal infiltration of activated immune cells have been postulated. Here we investigated mechanisms in retrovirus associated cardiomyopathy using a well-defined mouse model of acquired immunodeficiency. METHODS: Mice were dosed with LPBM5 retrovirus; cardiac performance was assessed by echocardiography followed by tissue collection at 5 and 10 weeks post-infection. RESULTS: Contractile deficits were observed at 5 and 10 weeks post-retrovirus infection and preceded the development of overt immunodeficiency. Selective and widespread cardiac infiltration of CD68+ cells, but not neutrophils, mast cells, or eosinophils was also observed at both 5 and 10 weeks. LPBM5 retrovirus was readily detectable in cardiac samples by RT-PCR. Time dependent increases in cardiac protein nitration (biomarker of reactive nitrogen species) were observed and were correlated to the extent of cardiac dysfunction whereas no changes in NOSII occurred at 5 and 10 weeks. We corroborated the mouse findings using cardiac tissues and clinical findings from human HIV/AIDS autopsies. CONCLUSIONS: These studies demonstrated that cardiac myocyte protein nitration in AIDS related cardiomyopathies, rather than focal immune cell lesions characterize retrovirus associated cardiomyopathies and differentiate them from non-retroviral cardiomyopathies.

Alterations in connexin 43 during diabetic cardiomyopathy: competition of tyrosine nitration versus phosphorylation.

BACKGROUND: Cardiac conduction abnormalities are observed early in the progression of type 1 diabetes (T1D), but the mechanism(s) involved are undefined. Connexin 43, a critical component of ventricular gap junctions, depends on tyrosine phosphorylation status to modulate channel conductance; changes in connexin 43 content, distribution, and/or phosphorylation status may be involved in cardiac rhythm disturbances. We tested the hypothesis that cardiac content and/or distribution of connexin 43 is altered in a rat model of T1D cardiomyopathy, investigating a mechanistic role for tyrosine. METHODS: Electrocardiographic analyses were conducted during the progression of diabetic cardiomyopathy in rats dosed with streptozotocin (STZ; 65 mg/kg) 3, 7, and 35 days after the induction of diabetes. Following functional analyses, we conducted immunohistochemical and immunoprecipitation studies to assess alterations in connexin 43. RESULTS: There was significant evidence of ventricular conduction abnormalities (QRS complex, Q-T interval) as early as 7 days after STZ, persisting throughout the study. Connexin 43 levels were increased 7 days after STZ and remained elevated throughout the study. Connexin 40 content was unchanged relative to controls throughout the study. Changes in connexin 43 distribution were also observed: connexin 43 staining was dispersed from myocyte short axis junctions. Connexin 43 tyrosine phosphorylation declined during the progression of diabetes, with concurrent increases in tyrosine nitration. CONCLUSIONS: The data suggest that changes in connexin 43 content and distribution occur during experimental diabetes and likely contribute to alterations in cardiac function, and that oxidative modification of tyrosine-mediated signaling may play a mechanistic role.

Activated Akt-1 in specific cell populations during multi-stage skin carcinogenesis.

The goal of the present study was to identify specific populations of cells that contain activated Akt-1, as determined by the presence ofphosphorylated Akt at serine 473 (p Akt), during development of skin tumors using a murine multi-stage carcinogenesis model. Nucleated papillomas cells as well as both epidermal and follicular keratinocytes in hyperplastic skin contained increased pAkt compared to skin treated only with acetone or 7, 12 dimethylbenz[a]anthracene (DMBA). Although the numbers of both mast cells and neutrophils were significantly increased in the stroma of papillomas (p<0.0005; p<0.0001, respectively), only mast cells contained pAkt. The amount of total Akt protein was similar regardless of time or treatment group examined. The present results suggest that activation of Akt-1 may provide specific populations of epidermal keratinocytes that develop into skin tumors with the ability to resist terminal differentiation and have enhanced proliferation during multi-stage skin carcinogenesis. In addition, mast cells which contain activated Akt-1 may persist within the stroma of papillomas during skin tumor development and progression through this signaling pathway, thereby contributing to a pro-oxidant and proangiogenic microenvironment.

Increased myocardial prevalence of C-reactive protein in human coronary heart disease: direct effects on microvessel density and endothelial cell survival.

BACKGROUND: Elevated plasma C-reactive protein (CRP) is a biomarker of cardiovascular diseases (CVDs), but its potential roles as a participant of the disease process are not well defined. Although early endothelial cell injury and dysfunction are recognized events in CVD, the initiating events are not well established. Here we investigated the local myocardial CRP levels and cardiac microvessel densities in control and CVD tissue samples. Using in vitro methodologies, we investigated the direct effects of CRP on human endothelial cells. METHODS: Cardiac specimens were collected at autopsy within 4 h of death and were classified as normal controls or documented evidence of CVD. The regional prevalence of CRP and the cardiac microvessels (<40 µm) were investigated using immunohistochemistry. For in vitro experiments, human umbilical vein endothelial cells were incubated with CRP. Intracellular oxidant levels were assessed using 2',7'-dichlorofluorescein diacetate fluorescence microscopy, and cell survival was concurrently determined. Effects of chemical antioxidants on endothelial cell survival were also tested. RESULTS: Myocardial CRP levels were elevated in CVD specimens. This was associated with reduced cardiac microvessels, and this rarefaction was inversely correlated to adjacent myocardial CRP prevalence. CRP caused concentration-dependent increases in oxidant production and cell apoptosis. CONCLUSIONS: These findings provide evidence supporting myocardial CRP as a locally produced inflammatory marker and as a potential participant in endothelial toxicity and microvascular rarefaction.

Effects of human endothelial gene polymorphisms on cellular responses to hyperglycaemia: role of NOS3 (Glu298Asp) and ACE (I/D) polymorphisms.

The functional relevance of NOS3 and ACE genetic variations to endothelial cell function is largely unstudied. Here we tested the functional relevance of the NOS3 (Glu298Asp) polymorphism and ACE (I/D) polymorphism in endothelial cells in vitro. Our hypothesis was that these genetic polymorphisms alter endothelial cell sensitivity to glucose and 3-nitrotyrosine (3NT). Genotyped HUVECs were incubated with glucose, free 3NT or a combination of these two toxicants. Significant differences in glucose-induced cell death and free 3NT-induced cell death were observed among the NOS3 genotypes. Combined glucose/3NT caused increased toxicity among the NOS3 genotypes. No differences were observed among the ACE genotypes in their responses to glucose/3NT. These data demonstrate that the NOS3 genotype may be an important predictor of, or be mechanistically involved in, endothelial vulnerability, whereas the ACE I/D genotype is apparently less important. Thus this NOS3 genetic variation may play a role in vulnerability to endothelium-dependent diabetic vascular complications.

Cardiac dysfunction in the R6/2 mouse model of Huntington's disease.

Recent evidence suggests that mutant huntingtin protein-induced energetic perturbations contribute to neuronal dysfunction in Huntington's disease (HD). Given the ubiquitous expression of huntingtin, other cell types with high energetic burden may be at risk for HD-related dysfunction. Early-onset cardiovascular disease is the second leading cause of death in HD patients; a direct role for mutant huntingtin in this phenomenon remains unevaluated. Here we tested the hypothesis that expression of mutant huntingtin is sufficient to induce cardiac dysfunction, using a well-described transgenic model of HD (line R6/2). R6/2 mice developed cardiac dysfunction by 8 weeks of age, progressing to severe failure at 12 weeks, assessed by echocardiography. Limited evidence of cardiac remodeling (e.g. hypertrophy, fibrosis, apoptosis, beta(1) adrenergic receptor downregulation) was observed. Immunogold electron microscopy demonstrated significant elevations in nuclear and mitochondrial polyglutamine presence in the R6/2 myocyte. Significant alterations in mitochondrial ultrastructure were seen, consistent with metabolic stress. Increased cardiac lysine acetylation and protein nitration were observed and were each significantly associated with impairments in cardiac performance. These data demonstrate that mutant huntingtin expression has potent cardiotoxic effects; cardiac failure may be a significant complication of this important experimental model of HD. Investigation of the potential cardiotropic effects of mutant huntingtin in humans may be warranted.

Altered expressions of fibroblast growth factor receptors and alveolarization in neonatal mice exposed to 85% oxygen.

In the present study, we tested the hypothesis that exposure of newborn mice to sublethal hyperoxia would alter lung development and expressions of fibroblast growth factor receptors (FGFRs)-3 and FGFR-4. Newborn FVB mice were exposed to 85% O2 or maintained in room air for up to 14 d. No animal mortality was observed, and body weight gains were not affected by hyperoxia. At postnatal d 7 and 14 (P7, P14), lungs of mice exposed to 85% O2 showed fewer alveolar secondary crests and larger alveoli or terminal air spaces than did mice in room air. In pups kept in room air, lung levels of FGFR-3 and FGFR-4 mRNA were greater at P3 than at P1, but similar increases were not observed in hyperoxic mice. Immunoreactivity of FGFR-3 and FGFR-4 was lower in lungs of hyperoxic mice than in controls at P14. In pups kept in room air, lung fibroblast growth factor (FGF)-7 mRNA levels were greater at P14 than at P1, but similar changes were not observed in hyperoxic mice. The temporally and spatially specific alterations in the expressions of FGFR-3, FGFR-4, and FGF-7 in the mice exposed to hyperoxia may contribute to aberrant lung development.

Bacterial lipopolysaccharide enhances cardiac dysfunction but not retroviral replication in murine AIDS: roles of macrophage infiltration and toll-like receptor 4 expression.

Cardiovascular disease is an important complication of human immunodeficiency virus/acquired immune deficiency syndrome (AIDS), but the mechanism(s) involved are poorly understood. Although co-infecting pathogens have been implicated as an important factor in AIDS progression, no studies have investigated these interactions in cardiac tissue. We recently demonstrated that the murine AIDS model (LPBM5 retroviral infection) mimics human immunodeficiency virus-related cardiac dysfunction and pathology. We tested the hypothesis that subseptic lipopolysaccharide exposure (LPS) would enhance LPBM5 progression and exacerbate cardiovascular dysfunction during murine AIDS development. LPS (5 mg/kg, Escherichia coli 0111:B4) was administered at 1, 6, and 8 weeks during LPBM5 infection, and cardiac performance was evaluated at 10 weeks using noninvasive echocardiography. LPS alone had no significant effects, whereas it amplified abnormalities in cardiac structure and function observed in murine AIDS. Cardiac dysfunction was associated with selective increases in nonfocal infiltration of CD68(+) cells and correlated with the extent of cardiac dysfunction. Retroviral progression and cardiac retroviral content remained unaltered, but cardiac toll-like receptor 4 was increased in retrovirus + LPS. We provide first-time evidence of multipathogen enhancements to retrovirus-related cardiac complications and implicate innate immune responses, not co-pathogen-induced retroviral replication, as the primary mechanism in this setting.