We examined ventilation and metabolism in four rat strains with variation in traits for body weight and/or blood pressure regulation. Sprague-Dawley [SD; 8 males (M), 8 females (F)], Brown Norway (BN; 10 M, 11 F), and Zucker (Z; 11 M, 12 F) rats were compared with Koletsky (K; 11 M, 11 F) rats. With the use of noninvasive plethysmography, frequency, tidal volume, minute ventilation (VE), O2 consumption, and CO2 production were derived at rest during normoxia (room air) and during the 5th minute of exposure to each of the following: hyperoxia (100% O2), hypoxia (10% O2-balance N2), and hypercapnia (7% CO2-balance O2). Statistical methods probed for strain and sex effects, with covariant analysis by body weight, length, and body mass. During resting breathing, strain effects were found with respect to both frequency (BN, Z > K, SD) and tidal volume (SD > BN, Z) but not to VE. Sex influenced frequency (F > M) alone. Z rats had higher values for O2 consumption, CO2 production, and respiratory quotient than the other three strains, with no independent effect by sex. During hyperoxia, frequency was greater in BN and Z than in SD or K rats; SD rats had a larger tidal volume than BN or Z rats; Z rats had a greater VE than K rats; and M had a larger tidal volume than F. Strain differences persisted during hypercapnia, with Z rats exhibiting the highest frequency and VE values. During hypoxic exposure, strain effects were found to influence VE (SD > K, Z), frequency (BN > K), and tidal volume (SD > BN, K, Z). Body mass was only a modest predictor of VE during normoxia, of both VE and tidal volume with hypoxia, hypercapnia, or hyperoxia, and of frequency during hypercapnia. We conclude that strain of rats, more than their body mass or sex, has major and different influences on metabolism, the pattern and level of ventilation during air breathing, and ventilation during acute exposure to hypercapnia or hypoxia.

Sexual differentiation of the mammalian brain is regulated by steroids during a critical developmental period, particularly by estradiol, which is believed to be aromatized in brain from gonadally derived testosterone. To ascertain the importance of neuronal estrogen receptor expression during sexual differentiation, we infused a 15-mer oligodeoxynucleotide antisense to the region of the translation start codon of estrogen receptor messenger RNA (mRNA), into the hypothalamus of 3-day-old rat pups. Two separate control treatments consisted of either a scrambled nucleotide sequence oligodeoxynucleotide, which had little homology to known mRNAs, or vehicle. Female pups either received a lightly androgenizing dose of testosterone 6 h after oligo infusion or were not hormone treated. Infusion of antisense oligo to estrogen receptor mRNA protected against many of the androgenizing effects of testosterone. Androgenized females infused with antisense oligo were significantly more likely to exhibit female sexual behavior in adulthood after treatment with estrogen plus progesterone and remained sensitive to the induction of wheel-running behavior by estrogen treatment seen in normal females, whereas the control androgenized females did not. Normal females did not exhibit any effects of antisense oligo treatment on sexual or locomotor behavior, but antisense oligo-treated normal females showed a trend (P = 0.09) toward disrupted estrous cyclicity and behaved differently in tests of open field behavior compared to controls. After killing, brains were processed for histology. Morphometric analysis of the sexually dimorphic nucleus of the preoptic area demonstrated a significantly smaller volume in antisense oligo-infused androgenized females compared with vehicle and scrambled oligo-infused controls. The sexually dimorphic nucleus volume was smaller still in normal females infused with antisense oligo, consistent with estrogen receptor activation playing an active role in sexual differentiation of the female brain. These results demonstrate the effectiveness of antisense oligodeoxynucleotides in permanently altering a developmental process if administered during a critical period.

Mortalin (mot-2) induces inactivation of the tumor suppressor p53's transcriptional and apoptotic functions by cytoplasmic sequestration of p53 in select cancers. The mot-2-dependent cytoprotective function enables cancer cells to support malignant transformation. Abrogating the p53-mot-2 interaction can control or slow down the growth of cancer cells. In this study, we report the discovery of a ubiquitin-like (UBX)-domain-containing protein, UBXN2A, which binds to mot-2 and consequently inhibits the binding between mot-2 and p53. Genetic analysis showed that UBXN2A binds to mot-2's substrate binding domain, and it partly overlaps p53's binding site indicating UBXN2A and p53 likely bind to mot-2 competitively. By binding to mot-2, UBXN2A releases p53 from cytosolic sequestration, rescuing the tumor suppressor functions of p53. Biochemical analysis and functional assays showed that the overexpression of UBXN2A and the functional consequences of unsequestered p53 trigger p53-dependent apoptosis. Cells expressing shRNA against UBXN2A showed the opposite effect of that seen with UBXN2A overexpression. The expression of UBXN2A and its apoptotic effects were not observed in normal colonic epithelial cells and p53−/− colon cancer cells. Finally, significant reduction in tumor volume in a xenograft mouse model in response to UBXN2A expression was verified in vivo. Our results introduce UBXN2A as a home defense response protein, which can reconstitute inactive p53-dependent apoptotic pathways. Inhibition of mot-2-p53 interaction by UBXN2A is an attractive therapeutic strategy in mot-2-elevated tumors.

Mortality associated with influenza virus super-infections is frequently due to secondary bacterial complications. To date, super-infections with Streptococcus pyogenes have been studied less extensively than those associated with S. pneumoniae. This is significant because a vaccine for S. pyogenes is not clinically available, leaving vaccination against influenza virus as our only means for preventing these super-infections. In this study, we directly compared immunity induced by two types of influenza vaccine, either inactivated influenza virus (IIV) or live, attenuated influenza virus (LAIV), for the ability to prevent super-infections. Our data demonstrate that both IIV and LAIV vaccines induce similar levels of serum antibodies, and that LAIV alone induces IgA expression at mucosal surfaces. Upon super-infection, both vaccines have the ability to limit the induction of pro-inflammatory cytokines within the lung, including IFN-γ which has been shown to contribute to mortality in previous models of super-infection. Limiting expression of these pro-inflammatory cytokines within the lungs subsequently limits recruitment of macrophages and neutrophils to pulmonary surfaces, and ultimately protects both IIV- and LAIV-vaccinated mice from mortality. Despite their overall survival, both IIV- and LAIV-vaccinated mice demonstrated levels of bacteria within the lung tissue to levels that are similar to those seen in unvaccinated mice. Thus, influenza virus:bacteria super-infections can be limited by vaccine-induced immunity against influenza virus, but the ability to prevent morbidity is not complete.

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Thyroid dysfunction is common in individuals with diabetes mellitus (DM) and may contribute to the associated cardiac dysfunction. However, little is known about the extent and pathophysiological consequences of low thyroid conditions on the heart in DM. DM was induced in adult female Sprague Dawley (SD) rats by injection of nicotinamide (N; 200 mg/kg) followed by streptozotocin (STZ; 65 mg/kg). One month after STZ/N, rats were randomized to the following groups (N = 10/group): STZ/N or STZ/N + 0.03 μg/mL T 3 ; age-matched vehicle-treated rats served as nondiabetic controls (C). After 2 months of T 3 treatment (3 months post-DM induction), left ventricular (LV) function was assessed by echocardiography and LV pressure measurements. Despite normal serum thyroid hormone (TH) levels, STZ/N treatment resulted in reductions in myocardial tissue content of THs (T 3 and T 4 : 39% and 17% reduction versus C, respectively). Tissue hypothyroidism in the DM hearts was associated with increased DIO3 deiodinase (which converts THs to inactive metabolites) altered TH transporter expression, reexpression of the fetal gene phenotype, reduced arteriolar resistance vessel density, and diminished cardiac function. Low-dose T 3 replacement largely restored cardiac tissue TH levels (T 3 and T 4 : 43% and 10% increase versus STZ/N, respectively), improved cardiac function, reversed fetal gene expression and preserved the arteriolar resistance vessel network without causing overt symptoms of hyperthyroidism. We conclude that cardiac dysfunction in chronic DM may be associated with tissue hypothyroidism despite normal serum TH levels. Low-dose T 3 replacement appears to be a safe and effective adjunct therapy to attenuate and/or reverse cardiac remodeling and dysfunction induced by experimental DM.

The purpose of the present study was to evaluate the effects of chronic mass loading produced by obesity on the structural and functional characteristics of the diaphragm in lean and obese Zucker rats. The trapezius muscle served as an internal control. The studies were carried out on 17 lean (303 +/- 24 g) and 16 obese (698 +/- 79 g) Zucker rats. We observed that the diaphragms from obese animals were restructured such that the overall contribution of type I and IIa fibers was significantly increased. As a consequence of this remodeling, overall diaphragm thickness was selectively greater in obese animals. In small isolated diaphragm bundles studied in vitro, we also detected a reduction in specific force in obese animals that was not detected in the trapezius muscle. In vitro fatigue resistance, assessed by repeated stimulation, was similar in muscles of lean and obese animals. Diaphragm fiber oxidative capacity (succinate dehydrogenase activity) was also comparable in lean and obese animals. We conclude that in obesity the diaphragm undergoes modest remodeling that may be beneficial in enhancing force generation.

. Treatment of subclinical hypothyroidism reverses ischemia and prevents myocyte loss and progressive LV dysfunction in hamsters with dilated cardiomyopathy. Am J Physiol Heart Circ Physiol 289: H2409 -H2415, 2005. First published July 15, 2005; doi:10.1152/ajpheart.00483.2005.-Growing evidence suggests that thyroid dysfunction may contribute to progression of cardiac disease to heart failure. We investigated the effects of a therapeutic dose of thyroid hormones (TH) on cardiomyopathic (CM) hamsters from 4 to 6 mo of age. CM hamsters had subclinical hypothyroidism (normal thyroxine, elevated TSH). Left ventricular (LV) function was determined by echocardiography and hemodynamics. Whole tissue pathology and isolated myocyte size and number were assessed. TH treatment prevented the decline in heart rate and rate of LV pressure increase and improved LV ejection fraction. The percentage of fibrosis/necrosis in untreated 4-mo-old CM (4CM; 15.5 Ϯ 2.2%) and 6-mo-old CM (6CM; 21.5 Ϯ 2.4%) hamsters was pronounced and was reversed in treated CM (TCM; 11.9 Ϯ 0.9%) hamsters. Total ventricular myocyte number was the same between 4-and 6-mo-old controls but was reduced by 30% in 4CM and 43% in 6CM hamsters. TH treatment completely prevented further loss of myocytes in TCM hamsters. Compared with agematched controls, resting and maximum coronary blood flow was impaired in 4CM and 6CM hamsters. Blood flow was completely normalized by TH treatment. We conclude that TH treatment of CM hamsters with subclinical hypothyroidism normalized impaired coronary blood flow, which prevented the decline in LV function and loss of myocytes. thyroid hormones; remodeling; fibrosis; blood flow THE EFFECTS OF THYROID HORMONES (TH) on the cardiovascular system have been well studied. It is clear that both hypothyroidism and hyperthyroidism can lead to deleterious changes in cardiovascular function. Decreased TH levels have been reported in a variety of nonthyroidal illnesses (18), including congestive heart failure (12) and myocardial infarction (6). The decrease in TH levels also appears to be related to the severity of heart failure (12). This is not a minor point, because low 3,5,3'-triiodothyronine (T 3 ) concentrations are a strong, independent predictive marker of poor prognosis in cardiac patients and might represent a determining factor directly implicated in the evolution and prognosis of these conditions (14). Growing evidence also suggests that subclinical thyroid dysfunction might play an important role in heart failure (10, 21). This is highly relevant from a clinical standpoint because this patient group does not typically receive TH treatment.Development of heart failure is accompanied by a variety of neuroendocrine changes. Cardiac failure was shown to be associated with both a decline in circulating TH levels (11,17) and altered cardiac TH signaling, as evidenced by changes in myocardial expression of TH nuclear receptor isoforms (15,16). The observation that short-term TH administration improves cardiac performance, both in anim...