Serum adiponectin is positively associated with lung function in young adults,independent of obesity: The CARDIA study

Rationale

Adipose tissue produces adiponectin, an anti-inflammatory protein. Adiponectin deficiency in mice is associated with abnormal post-natal alveolar development.

Objective

We hypothesized that lower serum adiponectin concentrations are associated with lower lung function in humans, independent of obesity. We explored mediation of this association by insulin resistance and systemic inflammation.

Methods and Measurements

Spirometry testing was conducted at years 10 and 20 follow-up evaluation visits in 2,056 eligible young adult participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Body mass index, serum adiponectin, serum C-reactive protein (a marker of systemic inflammation), and insulin resistance were assessed at year 15.

Main Results

After controlling for body mass index, years 10 and 20 forced vital capacity (FVC) were 81 ml and 82 ml lower respectively (p = 0.004 and 0.01 respectively) in the lowest vs. highest adiponectin quartiles. Similarly, years 10 and 20 forced expiratory volume in one second (FEV₁) were 50 ml and 38 ml lower (p = 0.01 and 0.09, respectively) in the lowest vs. highest adiponectin quartiles. These associations were no longer significant after adjustment for insulin resistance and C-reactive protein. Serum adiponectin was not associated with FEV₁/FVC or peak FEV₁.

Conclusions

Independent of obesity, lower serum adiponectin concentrations are associated with lower lung function. The attenuation of this association after adjustment for insulin resistance and systemic inflammation suggests that these covariates are on a causal pathway linking adiponectin and lung function.     

Mesenchymal Stem Cells Promote Mammosphere Formation and Decrease E-Cadherin in Normal and Malignant Breast Cells

Introduction

Normal and malignant breast tissue contains a rare population of multi-potent cells with the capacity to self-renew, referred to as stem cells, or tumor initiating cells (TIC). These cells can be enriched by growth as “mammospheres” in three-dimensional cultures.

Objective

We tested the hypothesis that human bone-marrow derived mesenchymal stem cells (MSC), which are known to support tumor growth and metastasis, increase mammosphere formation.

Results

We found that MSC increased human mammary epithelial cell (HMEC) mammosphere formation in a dose-dependent manner. A similar increase in sphere formation was seen in human inflammatory (SUM149) and non-inflammatory breast cancer cell lines (MCF-7) but not in primary inflammatory breast cancer cells (MDA-IBC-3). We determined that increased mammosphere formation can be mediated by secreted factors as MSC conditioned media from MSC spheroids significantly increased HMEC, MCF-7 and SUM149 mammosphere formation by 6.4 to 21-fold. Mammospheres grown in MSC conditioned media had lower levels of the cell adhesion protein, E-cadherin, and increased expression of N-cadherin in SUM149 and HMEC cells, characteristic of a pro-invasive mesenchymal phenotype. Co-injection with MSC in vivo resulted in a reduced latency time to develop detectable MCF-7 and MDA-IBC-3 tumors and increased the growth of MDA-IBC-3 tumors. Furthermore, E-cadherin expression was decreased in MDA-IBC-3 xenografts with co-injection of MSC.

Conclusions

MSC increase the efficiency of primary mammosphere formation in normal and malignant breast cells and decrease E-cadherin expression, a biologic event associated with breast cancer progression and resistance to therapy.     

Gastroprotective potential of risperidone, an atypical antipsychotic, against stress and pyloric ligation induced gastric lesions

Risperidone has been used in some stress disorders and may be potentially protective against stress-induced gastric lesions. Thus, the aim of the present study is to investigate, whether risperidone, a D(2) receptor and 5-HT(2A) receptor antagonist, would be able to result in gastroprotective effect in stress-induced lesions and also explore the possible mechanism of action behind its gastroprotective activity. Gastroprotective activity of risperidone was evaluated both by single treatment and 21 days repeated (0.03, 0.1, 0.3 and 1mg/kg, p.o.) treatment in the cold restraint stress (CRS) model and 21 days repeated treatment in the pyloric ligation (PL) model and compared with that of sulpiride (D(2) receptor antagonist) and ketanserin (5-HT(2) receptor antagonist) as standard. Histopathological assessment was done to evaluate the gastroprotective activity of risperidone in CRS model. The roles of nitric oxide (NO), sulfhydryl (SH) group, ATP-sensitive K(+) channels (K(ATP) channels) and prostaglandins (PGs) in the gastroprotective effect of risperidone against CRS were also investigated. PGE(2), hexosamine as a marker of mucus barrier and microvascular permeability were also estimated. Results show that repeated treatment of risperidone, sulpiride and ketanserin exhibited a gastroprotective effect against CRS-induced lesions while single administration of risperidone was found to be ineffective. Moreover, repeated treatment of risperidone and ketanserin was found to be ineffective in case of PL in contrast to sulpiride. Risperidone pretreatment reverses the stress induced alteration in hexosamine, PGE(2) and microvascular permeability. Pretreatment with l-NAME, NEM, glibenclamide and indomethacin reversed the gastroprotective effect of risperidone. The results suggest that risperidone has significant gastroprotective effects in CRS-induced gastric lesions models, which appears to be mediated by endogenous NO, SH, PGs and K(ATP) channel opening.     

Eliminating expression of erucic acid-encoding loci allows the identification of “hidden” QTL contributing to oil quality fractions and oil content in <Emphasis Type="Italic">Brassica juncea</Emphasis> (Indian mustard)

Oil content and oil quality fractions (viz., oleic, linoleic and linolenic acid) are strongly influenced by the erucic acid pathway in oilseed Brassicas. Low levels of erucic acid in seed oil increases oleic acid content to nutritionally desirable levels, but also increases the linoleic and linolenic acid fractions and reduces oil content in Indian mustard (Brassica juncea). Analysis of phenotypic variability for oil quality fractions among a high-erucic Indian variety (Varuna), a low-erucic east-European variety (Heera) and a zero-erucic Indian variety (ZE-Varuna) developed by backcross breeding in this study indicated that lower levels of linoleic and linolenic acid in Varuna are due to substrate limitation caused by an active erucic acid pathway and not due to weaker alleles or enzyme limitation. To identify compensatory loci that could be used to increase oil content and maintain desirable levels of oil quality fractions under zero-erucic conditions, we performed Quantitative Trait Loci (QTL) mapping for the above traits on two independent F1 doubled haploid (F1DH) mapping populations developed from a cross between Varuna and Heera. One of the populations comprised plants segregating for erucic acid content (SE) and was used earlier for construction of a linkage map and QTL mapping of several yield-influencing traits in B. juncea. The second population consisted of zero-erucic acid individuals (ZE) for which, an Amplified Fragment Length Polymorphism (AFLP)-based framework linkage map was constructed in the present study. By QTL mapping for oil quality fractions and oil content in the ZE population, we detected novel loci contributing to the above traits. These loci did not co-localize with mapped locations of the fatty acid desaturase 2 (FAD2), fatty acid desaturase 3 (FAD3) or fatty acid elongase (FAE) genes unlike those of the SE population wherein major QTL were found to coincide with mapped locations of the FAE genes. Some of the new loci identified in the ZE population could be detected as ‘weak’ contributors (with LOD < 2.5) in the SE population in which their contribution to the traits was “masked” due to pleiotropic effects of erucic acid genes. The novel loci identified in this study could now be used to improve oil quality parameters and oil content in B. juncea under zero-erucic conditions.     

Electromechanical coupling between the atria and mitral valve

Anterior leaflet (AL) stiffening during isovolumic contraction (IVC) may aid mitral valve closure. We tested the hypothesis that AL stiffening requires atrial depolarization. Ten sheep had radioopaque-marker arrays implanted in the left ventricle, mitral annulus, AL, and papillary muscle tips. Four-dimensional marker coordinates (x, y, z, and t) were obtained from biplane videofluoroscopy at baseline (control, CTRL) and during basal interventricular-septal pacing (no atrial contraction, NAC; 110-117 beats/min) to generate ventricular depolarization not preceded by atrial depolarization. Circumferential and radial stiffness values, reflecting force generation in three leaflet regions (annular, belly, and free-edge), were obtained from finite-element analysis of AL displacements in response to transleaflet pressure changes during both IVC and isovolumic relaxation (IVR). In CTRL, IVC circumferential and radial stiffness was 46 ± 6% greater than IVR stiffness in all regions (P < 0.001). In NAC, AL annular IVC stiffness decreased by 25% (P = 0.004) in the circumferential and 31% (P = 0.005) in the radial directions relative to CTRL, without affecting edge stiffness. Thus AL annular stiffening during IVC was abolished when atrial depolarization did not precede ventricular systole, in support of the hypothesis. The likely mechanism underlying AL annular stiffening during IVC is contraction of cardiac muscle that extends into the leaflet and requires atrial excitation. The AL edge has no cardiac muscle, and thus IVC AL edge stiffness was not affected by loss of atrial depolarization. These findings suggest one reason why heart block, atrial dysrhythmias, or ventricular pacing may be accompanied by mitral regurgitation or may worsen regurgitation when already present.     

Glutamate antagonism fails to reverse mitochondrial dysfunction in late phase of experimental neonatal asphyxia in rats

Because estrogen plays important neurotrophic and neuroprotective roles in the brain by activating estrogen receptors (ERs), disruption of normal estrogen signaling can leave neurons vulnerable to a variety of insults, including β-amyloid peptide (Aβ). Aroclor1254 (A1254) belongs to the endocrine-disrupting chemical (EDC) polychlorinated biphenyls and has anti-estrogenic properties. In the present study, we evaluated the effect of A1254 on the protective activity of estrogen against Aβ toxicity in differentiated cholinergic SN56 cells. Aged Aβ25-35 causes apoptotic cell death in differentiated SN56 cells, and the cytotoxic evidences are effectively rescued by estrogen. We found that A1254 abolishes the neuroprotective activity of estrogen against Aβ toxicity, and attenuates the suppressive effect of estrogen on Aβ-induced tau phosphorylation and JNK activation. The effects of A1254 on the neuroprotective effects of estrogen in Aβ toxicity are very similar to the effects of the estrogen receptor antagonist ICI182,780. Thus, exposure to EDCs that have anti-estrogenic activity might interfere with normal estrogen-activated neuroprotective signaling events and leave neurons more vulnerable to dangerous stimuli. Our present results provide new understanding of the mechanisms contributing to the harmful effects of EDCs on the function and viability of neurons, and the possible relevance of EDCs in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease.     

Mitral leaflet modeling: Importance of in vivo shape and material properties

The anterior mitral leaflet (AML) is a thin membrane that withstands high left ventricular (LV) pressure pulses 100,000 times per day. The presence of contractile cells determines AML in vivo stiffness and complex geometry. Until recently, mitral valve finite element (FE) models have neglected both of these aspects. In this study we assess their effect on AML strains and stresses, hypothesizing that these will differ significantly from those reported in literature. Radiopaque markers were sewn on the LV, the mitral annulus, and AML in sheep hearts, and their four-dimensional coordinates obtained with biplane video fluoroscopy. Employing in vivo data from three representative hearts, AML FE models were created from the marker coordinates at the end of isovolumic relaxation assumed as the unloaded reference state. AML function was simulated backward through systole, applying the measured trans-mitral pressure on AML LV surface and marker displacements on AML boundaries. Simulated AML displacements and curvatures were consistent with in vivo measurements, confirming model accuracy. AML circumferential strains were mostly tensile (1-3%), despite being compressive (-1%) near the commissures. Radial strains were compressive in the belly (-1 to -0.2%), and tensile (2-8%) near the free edge. These results differ significantly from those of previous FE models. They reflect the synergy of high tissue stiffness, which limits tensile circumferential strains, and initial compound curvature, which forces LV pressure to compress AML radially. The obtained AML shape may play a role not only in preventing mitral regurgitation, but also in optimizing LV outflow fluid dynamics.     

TNF receptor 1 deficiency increases regulatory T cell function in nonobese diabetic mice

TNF has been implicated in the pathogenesis of type 1 diabetes. When administered early in life, TNF accelerates and increases diabetes in NOD mice. However, when administered late, TNF decreases diabetes incidence and delays onset. TNFR1-deficient NOD mice were fully protected from diabetes and only showed mild peri-insulitis. To further dissect how TNFR1 deficiency affects type 1 diabetes, these mice were crossed to β cell-specific, highly diabetogenic TCR transgenic I-A(g7)-restricted NOD4.1 mice and Kd-restricted NOD8.3 mice. TNFR1-deficient NOD4.1 and NOD8.3 mice were protected from diabetes and had significantly less insulitis compared with wild type NOD4.1 and NOD8.3 controls. Diabetic NOD4.1 mice rejected TNFR1-deficient islet grafts as efficiently as control islets, confirming that TNFR1 signaling is not directly required for β cell destruction. Flow cytometric analysis showed a significant increase in the number of CD4(+)CD25(+)Foxp3(+) T regulatory cells in TNFR1-deficient mice. TNFR1-deficient T regulatory cells were functionally better at suppressing effector cells than were wild type T regulatory cells both in vitro and in vivo. This study suggests that blocking TNF signaling may be beneficial in increasing the function of T regulatory cells and suppression of type 1 diabetes.     

Structural variation in bacterial glyoxalase I enzymes: investigation of the metalloenzyme glyoxalase I from Clostridium acetobutylicum

The glyoxalase system catalyzes the conversion of toxic, metabolically produced α-ketoaldehydes, such as methylglyoxal, into their corresponding nontoxic 2-hydroxycarboxylic acids, leading to detoxification of these cellular metabolites. Previous studies on the first enzyme in the glyoxalase system, glyoxalase I (GlxI), from yeast, protozoa, animals, humans, plants, and Gram-negative bacteria, have suggested two metal activation classes, Zn(2+) and non-Zn(2+) activation. Here, we report a biochemical and structural investigation of the GlxI from Clostridium acetobutylicum, which is the first GlxI enzyme from Gram-positive bacteria that has been fully characterized as to its three-dimensional structure and its detailed metal specificity. It is a Ni(2+)/Co(2+)-activated enzyme, in which the active site geometry forms an octahedral coordination with one metal atom, two water molecules, and four metal-binding ligands, although its inactive Zn(2+)-bound form possesses a trigonal bipyramidal geometry with only one water molecule liganded to the metal center. This enzyme also possesses a unique dimeric molecular structure. Unlike other small homodimeric GlxI where two active sites are located at the dimeric interface, the C. acetobutylicum dimeric GlxI enzyme also forms two active sites but each within single subunits. Interestingly, even though this enzyme possesses a different dimeric structure from previously studied GlxI, its metal activation characteristics are consistent with properties of other GlxI. These findings indicate that metal activation profiles in this class of enzyme hold true across diverse quaternary structure arrangements.