Venous arterialization occurs when a vein segment is transposed as a bypass graft into the arterial circulation, resulting in a structural and functional reorganization of the vascular wall in response to the new local biomechanical environment. Although the anatomical changes of venous arterialization have been well characterized, the molecular mechanisms of vascular remodeling remain incompletely understood. Here, we present a novel model of venous arterialization in mice wherein the external jugular vein is connected to the common carotid artery. The hemodynamic characteristics of the arterialized vein, as assessed by ultrasound and magnetic resonance imaging, resemble features of the arterial circulation. Temporal analyses of the morphological changes in the venous segment at 1, 3, and 7 days after surgery demonstrate preservation of the endothelium at all time points and formation of multiple smooth muscle layers by day 7. Expression of endothelial E-selectin and VCAM-1 was documented at early time points, concomitant with the presence of neutrophils and monocytes/macrophages in the vascular wall. In addition, endothelium-dependent permeability was decreased in the arterialized vein when compared to the contralateral control vein. Thus, this novel mouse model of venous arterialization displays anatomical and cellular features present in other species, and should help to characterize the molecular mechanisms of this adaptive response of the vascular wall to changes in its biomechanical environment.
BackgroundAge is one of the most important risk factors for developing breast cancer. However, age-related changes in normal breast tissue that potentially lead to breast cancer are incompletely understood. Quantifying tissue-level DNA methylation can contribute to understanding these processes. We hypothesized that occurrence of breast cancer should be associated with an acceleration of epigenetic aging in normal breast tissue.ResultsNinety-six normal breast tissue samples were obtained from 88 subjects (breast cancer = 35 subjects/40 samples, unaffected = 53 subjects/53 samples). Normal tissue samples from breast cancer patients were obtained from distant non-tumor sites of primary mastectomy specimens, while samples from unaffected women were obtained from the Komen Tissue Bank (n = 25) and from non-cancer-related breast surgery specimens (n = 28). Patients were further stratified into four cohorts: age < 50 years with and without breast cancer and age ≥ 50 with and without breast cancer. The Illumina HumanMethylation450k BeadChip microarray was used to generate methylation profiles from extracted DNA samples. Data was analyzed using the “Epigenetic Clock,” a published biomarker of aging based on a defined set of 353 CpGs in the human genome. The resulting age estimate, DNA methylation age, was related to chronological age and to breast cancer status.The DNAmAge of normal breast tissue was strongly correlated with chronological age (r = 0.712, p < 0.001). Compared to unaffected peers, breast cancer patients exhibited significant age acceleration in their normal breast tissue (p = 0.002). Multivariate analysis revealed that epigenetic age acceleration in the normal breast tissue of subjects with cancer remained significant after adjusting for clinical and demographic variables. Additionally, smoking was found to be positively correlated with epigenetic aging in normal breast tissue (p = 0.012).ConclusionsWomen with luminal breast cancer exhibit significant epigenetic age acceleration in normal adjacent breast tissue, which is consistent with an analogous finding in malignant breast tissue. Smoking is also associated with epigenetic age acceleration in normal breast tissue. Further studies are needed to determine whether epigenetic age acceleration in normal breast tissue is predictive of incident breast cancer and whether this mediates the risk of chronological age on breast cancer risk.Electronic supplementary materialThe online version of this article (10.1186/s13148-018-0534-8) contains supplementary material, which is available to authorized users.
Adipocytes undergo pronounced changes in size and behavior to support diverse tissue functions, but the mechanisms that control these changes are not well understood. Mammary gland-associated white adipose tissue (mgWAT) regresses in support of milk fat production during lactation and expands during the subsequent involution of milk-producing epithelial cells, providing one of the most marked physiological examples of adipose growth. We examined cellular mechanisms and functional implications of adipocyte and lipid dynamics in the mouse mammary gland (MG). Using in vivo analysis of adipocyte precursors and genetic tracing of mature adipocytes, we find mature adipocyte hypertrophy to be a primary mechanism of mgWAT expansion during involution. Lipid tracking and lipidomics demonstrate that adipocytes fill with epithelial-derived milk lipid. Furthermore, ablation of mgWAT during involution reveals an essential role for adipocytes in milk trafficking from, and proper restructuring of, the mammary epithelium. This work advances our understanding of MG remodeling and tissue-specific roles for adipocytes.
Treatment of type 2 diabetes mellitus continues to pose an important clinical challenge, with most existing therapies lacking demonstrable ability to improve cardiovascular outcomes. The atheroprotective peptide apelin (APLN) enhances glucose utilization and improves insulin sensitivity. However, the mechanism of these effects remains poorly defined. We demonstrate that the expression of APLNR (APJ/AGTRL1), the only known receptor for apelin, is predominantly restricted to the endothelial cells (ECs) of multiple adult metabolic organs, including skeletal muscle and adipose tissue. Conditional endothelial-specific deletion of Aplnr (AplnrECKO) resulted in markedly impaired glucose utilization and abrogation of apelin-induced glucose lowering. Furthermore, we identified in-activation of Forkhead box protein O1 (FOXO1) and inhibition of endothelial expression of fatty acid (FA) binding protein 4 (FABP4) as key downstream signaling targets of apelin/APLNR signaling. Both the Apln−/− and AplnrECKO mice demonstrated increased endothelial FABP4 expression and excess tissue FA accumulation, whereas concurrent endothelial Foxo1 deletion or pharmacologic FABP4 inhibition rescued the excess FA accumulation phenotype of the Apln−/− mice. The impaired glucose utilization in the AplnrECKO mice was associated with excess FA accumulation in the skeletal muscle. Treatment of these mice with an FABP4 inhibitor abrogated these metabolic phenotypes. These findings provide mechanistic insights that could greatly expand the therapeutic repertoire for type 2 diabetes and related metabolic disorders.
Although the total effective body doses under lead fell within established ICRP occupational exposure limits, they are not negligible. Because radiation exposure is cumulative and endovascular procedures are becoming more common, individuals performing these procedures must carefully monitor their exposure. Our results indicate that a team of surgeons can perform 386 hours of fluoroscopy per year or 587 EAIA repairs per year and remain within occupational exposure limits. Individuals who perform these procedures should actively monitor their effective doses and educate personnel in methods for reducing exposure.
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