Duration of diabetes, glycemic control, and low heart rate variability: The Atherosclerosis Risk in Communities (ARIC) study.

Persons with long-standing, poorly controlled diabetes or recent hyperglycemia had the highest burden of cardiac autonomic neuropathy. Cardiac autonomic neuropathy contributed to elevated long-term incidence of cardiovascular disease and mortality even in persons with well-controlled diabetes.

Differences in oxidative stress status and expression of MKP-1 in dorsal medulla of transgenic rats with altered brain renin-angiotensin system.

ANG II-stimulated production of reactive oxygen species (ROS) through NADPH oxidase is suggested to activate MAPK pathways, which are implicated in neurally mediated pressor effects of ANG II. Emerging evidence suggests that ANG-(1-7) up regulates MAPK phosphatases to reduce MAPK signaling and attenuate actions of ANG II. Whether angiotensin peptides participate in long-term regulation of these systems in the brain is not known.

WE-E-213AB-01: Medical Physics Challenges for Implementation of New Technologies in External Beam Radiotherapy.

Unlabelled: The AAPM has signed two formal Educational Exchange Agreements with the Spanish (SEFM) and the Russian (AMPR) medical physics societies. While the primary purpose of the Agreements is to provide educational opportunities for young medical physicists, the Agreements also contemplate holding joint sessions at scientific congresses. The purpose of this professional AAPM/SEFM/AMPR Joint Symposium is to explore the challenges that medical physicists in the three countries face when new external beam radiotherapy technologies are introduced in their facilities and to suggest potential solutions to limitations in testing equipment and lack of familiarity with protocols.

SU-E-J-56: Localization Error in Gamma Radiosurgery with 3T MR Due to Fiducial Box Chemical Shift from Incorrect Liquid Filling Materials.

Purpose: Use of a 3D MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) polymer gel dosimeter to evaluate potential localization and positioning errors due to the use of incorrect liquid filling material (baby oil instead of copper sulfate) for a gamma radiosurgery (GSR) MRI fiducial box.

Method And Materials: Two phantoms were used to evaluate geometric errors due to chemical shift for 'baby oil' fiducial markers: 1) a cylindrical grid phantom with Teflon rod insert; 2) a human skull phantom with a MAGIC (Gelatin 9%; Methacrylic acid 4%; CuSO4 0.1mM; Ascorbic acid 2mM; Glucose 10%) gel capsule to simulate an intracranial target.

SU-E-T-99: Small Field Output Factor Measurement Using MAGIC Gel Dosimeter in 3T MRI.

Purpose: Small field dosimetry is very important because of radiation therapy techniques that use small fields such as IMRT, gamma and body radiosurgery, cyberknife and tomotherapy. We investigated use of a MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) gel dosimeter to quantitatively measure small field output factors (OFs) for 6MV x rays.

Methods: In this work, MAGIC (Gelatin 9%; Methacrylic acid 4%; CuSO4 0.

Hydroxyproline metabolism in mouse models of primary hyperoxaluria.

Primary hyperoxaluria type 1 (PH1) and type 2 (PH2) are rare genetic diseases that result from deficiencies in glyoxylate metabolism. The increased oxalate synthesis that occurs can lead to kidney stone formation, deposition of calcium oxalate in the kidney and other tissues, and renal failure. Hydroxyproline (Hyp) catabolism, which occurs mainly in the liver and kidney, is a prominent source of glyoxylate and could account for a significant portion of the oxalate produced in PH.

Cholinergic modulation of working memory activity in primate prefrontal cortex.

The prefrontal cortex, a cortical area essential for working memory and higher cognitive functions, is modulated by a number of neurotransmitter systems, including acetylcholine; however, the impact of cholinergic transmission on prefrontal activity is not well understood. We relied on systemic administration of a muscarinic receptor antagonist, scopolamine, to investigate the role of acetylcholine on primate prefrontal neuronal activity during execution of working memory tasks and recorded neuronal activity with chronic electrode arrays and single electrodes. Our results indicated a dose-dependent decrease in behavioral performance after scopolamine administration in all the working memory tasks we tested.

Autonomic control of the heart is altered in Sprague-Dawley rats with spontaneous hydronephrosis.

The renal medulla plays an important role in cardiovascular regulation, through interactions with the autonomic nervous system. Hydronephrosis is characterized by substantial loss of renal medullary tissue. However, whether alterations in autonomic control of the heart are observed in this condition is unknown.

Nuclear angiotensin-(1-7) receptor is functionally coupled to the formation of nitric oxide.

The kidney is an important target for the actions of the renin-angiotensin system (RAS) and this tissue contains a complete local RAS that expresses the bioactive peptides angiotensin II (ANG II) and Ang-(1-7). We find both angiotensin type 1 (AT(1)R) and type 2 (AT(2)R) receptors expressed on renal nuclei that stimulate reactive oxygen species and nitric oxide (NO), respectively. Since Ang-(1-7) also exhibits actions within the kidney and the Ang-(1-7)/Mas receptor protein contains a nuclear localization sequence, we determined the expression of Ang-(1-7) receptors in nuclei isolated from the kidneys of young adult sheep.

Prenatal betamethasone exposure alters renal function in immature sheep: sex differences in effects.

Synthetic glucocorticoids are commonly given to pregnant women when premature delivery threatens. Antenatal administration of clinically relevant doses of betamethasone to pregnant sheep causes sex-specific compromises of renal function and increases in blood pressure in adult offspring. However, it is unclear whether such effects are present in immature lambs.

Acute AT(1)-receptor blockade reverses the hemodynamic and baroreflex impairment in adult sheep exposed to antenatal betamethasone.

To accelerate lung development and protect neonates from other early developmental problems, synthetic steroids are administered maternally in the third trimester, exposing fetuses that are candidates for premature delivery to them. However, steroid exposure at this point of gestation may lead to elevated blood pressure [mean arterial pressure (MAP)] during adolescence. We hypothesize that fetal exposure to steroids activates the renin-angiotensin system, inducing an elevation in blood pressure and attenuation of baroreflex sensitivity (BRS) that is angiotensin II dependent in early adulthood.

Mild chronic hypoxemia modifies expression of brain stem angiotensin peptide receptors and reflex responses in fetal sheep.

The effects of chronic mild hypoxemia on the binding of angiotensin receptors in selected brain stem nuclei and reflex responses were studied in fetal sheep. Fetal and maternal catheters were placed at 120 days' gestation, and animals received intratracheal maternal administration of nitrogen (n = 16) or compressed air in controls (n = 19). Nitrogen infusion was adjusted to reduce fetal brachial artery PO(2) by 25% during 5 days.

Nuclear angiotensin II type 2 (AT2) receptors are functionally linked to nitric oxide production.

Expression of nuclear angiotensin II type 1 (AT(1)) receptors in rat kidney provides further support for the concept of an intracellular renin-angiotensin system. Thus we examined the cellular distribution of renal ANG II receptors in sheep to determine the existence and functional roles of intracellular ANG receptors in higher order species. Receptor binding was performed using the nonselective ANG II antagonist (125)I-[Sar(1),Thr(8)]-ANG II ((125)I-sarthran) with the AT(1) antagonist losartan (LOS) or the AT(2) antagonist PD123319 (PD) in isolated nuclei (NUC) and plasma membrane (PM) fractions obtained by differential centrifugation or density gradient separation.

Differential regulation of angiotensin-(1-12) in plasma and cardiac tissue in response to bilateral nephrectomy.

We examined the effects of 48 h bilateral nephrectomy on plasma and cardiac tissue expression of angiotensin-(1-12) [ANG-(1-12)], ANG I, and ANG II in adult Wistar-Kyoto rats to evaluate functional changes induced by removing renal renin. The goal was to expand the evidence of ANG-(1-12) being an alternate renin-independent, angiotensin-forming substrate. Nephrectomy yielded divergent effects on circulating and cardiac angiotensins.

Cortisol infusion in late-gestation hypothalamo-pituitary disconnected sheep fetus restores pituitary cell responsiveness to arginine vasopressin.

Corticotrophs in the fetal sheep become increasingly responsive to arginine vasopressin (AVP) in late gestation. We previously reported that this may be due in part to corresponding increases in signal transduction (inositol 1,4,5-trisphosphate, IP(3)). These ontogenic changes are prevented by hypothalamo-pituitary disconnection (HPD), which also prevents fetal plasma cortisol concentrations from increasing in late gestation.

Regulation of ACE2 in cardiac myocytes and fibroblasts.

Angiotensin-converting enzyme 2 (ACE2) preferentially forms angiotensin-(1-7) [ANG-(1-7)] from ANG II. We showed that cardiac ACE2 is elevated following treatment of coronary artery-ligated rats with AT1 receptor blockers (ARBs). Cardiac myocytes and fibroblasts were isolated from neonatal rats to determine the molecular mechanisms for the ACE2 upregulation by ARB treatment.

MAP kinase/phosphatase pathway mediates the regulation of ACE2 by angiotensin peptides.

Angiotensin-converting enzyme 2 (ACE2) catalyzes the conversion of the vasoconstrictor angiotensin II (ANG II) to the vasodilatory peptide angiotensin-(1-7) [ANG-(1-7)]. We showed that treatment of hypertensive rats with the AT(1) receptor antagonist olmesartan increased ACE2 mRNA and protein in the thoracic aorta, suggesting that endogenous ANG II tonically reduces the enzyme. We now report that ANG II downregulates ACE2 activity and mRNA in rat aortic vascular smooth muscle cells (VSMCs) to reduce the conversion of ANG II to ANG-(1-7).

Cerebromicrovascular endothelial cells are resistant to L-glutamate.

Cerebral microvascular endothelial cells (CMVECs) have recently been implicated as targets of excitotoxic injury by l-glutamate (l-glut) or N-methyl-d-aspartate (NMDA) in vitro. However, high levels of l-glut do not compromise the function of the blood-brain barrier in vivo. We sought to determine whether primary cultures of rat and piglet CMVECs or cerebral microvascular pericytes (CMVPCs) are indeed sensitive to l-glut or NMDA.

Sex differences in circulating and renal angiotensins of hypertensive mRen(2). Lewis but not normotensive Lewis rats.

Sex differences in blood pressure are evident in experimental models and human subjects, yet the mechanisms underlying this disparity remain equivocal. The current study sought to define the extent of male-female differences in the circulating and tissue renin-angiotensin aldosterone systems (RAASs) of congenic mRen(2). Lewis and control Lewis rats.

Nonrigid registration of images with different topologies using embedded maps.

Changes in image topology occur in medical images due to normal variation in anatomy, image artifacts, and the presence of pathology. Non-rigid registration of images undergoing topological change for the purpose of atlas-based segmentation or deformation analysis is challenging since non-smooth geometric transformations must be introduced. As most registration methods impose a smoothness constraint on the allowable transformations they either do not model such changes or perform poorly in their presence.

Leg flow-mediated arterial dilation in elderly patients with heart failure and normal left ventricular ejection fraction.

Background: flow-mediated arterial dilation (FMAD), an indicator of endothelial function, is reduced in patients with heart failure and reduced left ventricular ejection fraction (HFREF). Many elderly patients with heart failure exhibit a normal left ventricular ejection fraction (HFNEF). It is unknown whether FMAD is severely reduced in the elderly with HFNEF.

Baroreceptor reflex regulation in anesthetized transgenic rats with low glia-derived angiotensinogen.

Endogenous angiotensin (ANG) II and ANG-(1-7) act at the nucleus tractus solitarius (NTS) to differentially modulate neural control of the circulation. The role of these peptides endogenous to NTS on cardiovascular reflex function was investigated in transgenic rats with low brain angiotensinogen (Aogen) due to glial overexpression of an antisense to Aogen (ASrAOGEN) and in Sprague-Dawley (SD) rats. Arterial baroreceptor reflex sensitivity (BRS) for control of heart rate (HR) in response to increases in mean arterial pressure (MAP) was tested before and after bilateral microinjection of the angiotensin type 1 (AT(1)) receptor blocker candesartan or the ANG-(1-7) receptor blocker (d-Ala(7))-ANG-(1-7) into the NTS of urethane-chloralose-anesthetized ASrAOGEN and SD rats.

Characteristics of myogenic tone in the rat ophthalmic artery.

The pressure-induced constriction in the rat ophthalmic artery was characterized. Ophthalmic arteries were isolated, cannulated in an arteriograph, and pressurized. Arteries developed 25% constriction at 70 mmHg of intraluminal pressure.

Estrogen and salt sensitivity in the female mRen(2). Lewis rat.

The present study determined whether early loss of estrogen influences salt-sensitive changes in blood pressure, renal injury, and cardiac hypertrophy as well as the effects on the circulating renin-angiotensin-aldosterone system (RAAS) in the hypertensive female mRen(2). Lewis strain. Ovariectomy (OVX) of heterozygous mRen(2).