bluuebunny/crossref_metadata_2025 huggingface dataset:
Synchrony between circular and longitudinal muscle contractions during peristalsis in normal subjects
Authors: Mittal Ravinder K. , Padda Bikram , Bhalla Vikas , Bhargava Valmik , Liu Jianmin
Published: October 2005

The current understanding is that longitudinal muscle contraction begins before and outlasts circular muscle contraction during esophageal peristalsis in normal subjects. The goal of our study was to reassess the relationship between the contractility of two muscle layers using novel ways to look at the muscle contraction. We studied normal subjects using synchronized high-frequency ultrasound imaging and manometry. Swallow-induced peristalsis was recorded at 5 and 10 cm above the lower esophageal sphincter (LES). Ultrasound (US) images were analyzed for muscle cross-sectional area (CSA) and circularity index of the esophagus during various phases of esophageal contraction. A plot of the M mode US image, muscle CSA, and esophageal circularity index was developed to assess the temporal correlation between various parameters. The muscle CSA wave began before and lasted longer than the contraction pressure wave at both 5 and 10 cm above the LES. M mode US images revealed that the onset of muscle CSA wave was temporally aligned with the onset of lumen collapse. The peak muscle CSA occurred in close proximity with the peak pressure wave. The esophagus started to become more circular (decrease in circularity index) with the onset of the muscle CSA wave. The circularity index and muscle CSA returned to the baseline at approximately the same time. In conclusion, the onset of lumen collapse and return of circularity index of the esophagus are likely to be the true markers of the onset and end of circular muscle contraction. Circular and longitudinal muscle layers of the esophagus contract in a precise synchronous fashion during peristalsis in normal subjects.
Albumin turnover: FcRn-mediated recycling saves as much albumin from degradation as the liver produces
Authors: Kim Jonghan , Bronson C. L. , Hayton William L. , Radmacher Michael D. , Roopenian Derry C. , Robinson John M. , Anderson Clark L.
Published: October 2005

It is now understood that the nonclassical major histocompatibility complex-I molecule FcRn binds albumin and retrieves it from an intracellular degradative fate. Whether FcRn in the liver modulates albumin turnover through effects on biosynthesis and production is not known. Thus we quantified the appearance of biosynthetically labeled albumin in plasma after an intravenous bolus injection of [3H]leucine in FcRn-deficient mice. The production rates for both albumin (FcRn substrate) and transferrin (nonsubstrate) are increased by ∼20% in FcRn-deficient mice compared with normal mice, likely compensating for the lowered plasma oncotic pressure caused by hypoalbuminemia in FcRn-deficient mice. Determining the magnitude of FcRn-mediated effects on albumin turnover, we then measured the steady-state plasma concentrations of biosynthetically labeled albumin and transferrin during [3H]leucine infusion. The concentration of albumin was ∼40% lower in FcRn-deficient mice compared with normal mice. Furthermore, the ∼40% lower plasma albumin concentration in FcRn-deficient mice along with the ∼20% increase in albumin production indicate, by the mass-balance equation, that albumin degradation in FcRn-deficient mice is twice that of normal mice. These studies of biosynthetically labeled, and thus native, albumin support our previous finding that FcRn protects albumin from degradation. Permitting quantification of the magnitude of FcRn-mediated recycling, they further indicate that FcRn has extraordinary capacity: the amount of albumin saved from degradation by FcRn-mediated recycling is the same as that produced by the liver.
Thioredoxin and dihydrolipoic acid inhibit elastase activity in cystic fibrosis sputum
Authors: Lee Rees L. , Rancourt Raymond C. , del Val Greg , Pack Kami , Pardee Churee , Accurso Frank J. , White Carl W.
Published: October 2005

Excessive neutrophil elastase activity within airways of cystic fibrosis (CF) patients results in progressive lung damage. Disruption of disulfide bonds on elastase by reducing agents may modify its enzymatic activity. Three naturally occurring dithiol reducing systems were examined for their effects on elastase activity: 1) Escherichia coli thioredoxin (Trx) system, 2) recombinant human thioredoxin (rhTrx) system, and 3) dihydrolipoic acid (DHLA). The Trx systems consisted of Trx, Trx reductase, and NADPH. As shown by spectrophotometric assay of elastase activity, the two Trx systems and DHLA inhibited purified human neutrophil elastase as well as the elastolytic activity present in the soluble phase (sol) of CF sputum. Removal of any of the three Trx system constituents prevented inhibition. Compared with the monothiols N-acetylcysteine and reduced glutathione, the dithiols displayed greater elastase inhibition. To streamline Trx as an investigational tool, a stable reduced form of rhTrx was synthesized and used as a single component. Reduced rhTrx inhibited purified elastase and CF sputum sol elastase without NADPH or Trx reductase. Because Trx and DHLA have mucolytic effects, we investigated changes in elastase activity after mucolytic treatment. Unprocessed CF sputum was directly treated with reduced rhTrx, the Trx system, DHLA, or DNase. The Trx system and DHLA did not increase elastase activity, whereas reduced rhTrx treatment increased sol elastase activity by 60%. By contrast, the elastase activity after DNase treatment increased by 190%. The ability of Trx and DHLA to limit elastase activity combined with their mucolytic effects makes these compounds potential therapies for CF.
Congenital diaphragmatic hernia prevents absorption of distal air space fluid in late-gestation rat fetuses
Authors: Folkesson Hans G. , Chapin Cheryl J. , Beard LaMonta L. , Ertsey Robert , Matthay Michael A. , Kitterman Joseph A.
Published: October 2005

We hypothesized that congenital diaphragmatic hernia (CDH) may decrease distal air space fluid absorption due to immaturity of alveolar epithelial cells from a loss of the normal epithelial Na+ transport, as assessed by amiloride and epithelial Na+ channel (ENaC) and Na-K-ATPase expression, as well as failure to respond to endogenous epinephrine as assessed by propranolol. Timed-pregnant dams were gavage fed 100 mg of nitrofen at 9.5-day gestation to induce CDH in the fetuses, and distal air space fluid absorption experiments were carried out on 22-day gestation (term) fetuses. Controls were nitrofen-exposed fetuses without CDH. Absorption of distal air space fluid was measured from the increase in 131I-albumin concentration in an isosmolar, physiological solution instilled into the developing lungs. In controls, distal air space fluid absorption was rapid and mediated by β-adrenoceptors as demonstrated by reversal to fluid secretion after propranolol. Normal lung fluid absorption was also partially inhibited by amiloride. In contrast, CDH fetuses continued to show lung fluid secretion, and this secretion was not affected by either propranolol or amiloride. CDH lungs showed a 67% reduction in α-ENaC and β-ENaC expression, but no change in α1-Na-K-ATPase expression. These studies demonstrate: 1) CDH delays lung maturation with impaired distal air space fluid absorption secondary to inadequate Na+ uptake by the distal lung epithelium that results in fluid-filled lungs at birth with reduced capacity to establish postnatal breathing, and 2) the main stimulus to lung fluid absorption in near-term control fetuses, elevated endogenous epinephrine levels, is not functional in CDH fetuses.
Stage-specific regulation of respiratory epithelial cell differentiation by Foxa1
Authors: Besnard V. , Wert S. E. , Kaestner K. H. , Whitsett J. A.
Published: October 2005

Foxa1 is a member of the winged helix family of transcription factors that is expressed in epithelial cells of the conducting airways and in alveolar type II cells of the lung. To determine the role of Foxa1 during lung morphogenesis, histology and gene expression were assessed in lungs from Foxa1−/−gene-targeted mice from embryonic day (E) 16.5 to postnatal day (PN) 13. Deletion of Foxa1 perturbed maturation of the respiratory epithelium at precise times during lung morphogenesis. While dilatation of peripheral lung saccules was delayed in Foxa1−/−mice at E16.5, sacculation was unperturbed later in development (E17.5–E18.5). At PN5, alveolarization was markedly delayed in Foxa1−/−mice; however, by PN13 lung histology was comparable to wild-type controls. Clara cell secretory protein (CCSP), prosurfactant protein (SP)-C, and SP-B protein content and immunostaining were decreased in Foxa1−/−mice between E16.5 and E18.5 but normalized after birth. Timing and sites of expression of thyroid transcription factor-1, Foxj1, and β-tubulin were unaltered in lungs of Foxa1−/−mice. In vitro, Foxa1 regulated the activity of CCSP and SP-A, SP-B, SP-C, and SP-D promoters as assessed by luciferase reporter assays in HeLa, H441, and MLE15 cells. Although Foxa1 regulates respiratory epithelial differentiation and structural maturation of the lung at precise developmental periods, the delay in maturation is subsequently compensated at times to enable respiratory function and restore normal lung structure after birth.
Effects of central and systemic administration of leptin on neurotransmitter concentrations in specific areas of the hypothalamus
Authors: Clark Kimberly A. , MohanKumar Sheba M. J. , Kasturi Badrinarayanan S. , MohanKumar P. S.
Published: October 2005

Leptin, a hormone produced by adipocytes, has been shown to affect a number of central functions, such as regulation of the hypothalamo-pituitary-adrenal axis, feeding, and body weight regulation. Because hypothalamic monoamines are intricately involved in the regulation of these functions, we hypothesized that leptin may produce its effects by altering the activity of these neurotransmitters. To test this hypothesis, male rats received peripheral (0, 100, or 500 μg ip), or central (0 or 5 μg icv) injections of leptin. The animals were killed 5 h later, and their brains were removed, frozen, and sectioned. Serum was collected to measure leptin and corticosterone by RIA. The paraventricular nucleus (PVN), arcuate nucleus (AN), ventromedial hypothalamus (VMH), dorsomedial dorsal nucleus (DMD), median eminence (ME), and medial preoptic area (MPA) were obtained using Palkovits' microdissection technique, and monoamine concentrations in these areas were determined using HPLC-EC. Intraperitoneal administration of leptin increased serum leptin concentrations in a dose-dependent manner ( P < 0.05). Both intraperitoneal and intracerebroventricular administration of leptin decreased serum corticosterone significantly ( P < 0.05). Norepinephrine (NE) concentration decreased significantly in the PVN, AN, and VMH after both intraperitoneal and intracerebroventricular administration of leptin ( P < 0.05). NE concentrations decreased significantly in the DMN after intracerebroventricular administration of leptin ( P < 0.05). Leptin treatment (both ip and icv) decreased dopamine concentrations significantly in the PVN. Serotonin (5-HT) concentration decreased significantly in the PVN after both intraperitoneal and intracerebroventricular injections of leptin and decreased in the VMH only with intracerebroventricular treatment of leptin. Leptin did not affect any of the monoamines in the ME and MPA. These results indicate that both central and systemic administration of leptin can affect hypothalamic monoamines in a region-specific manner, which, in turn, could mediate many of leptin's central and neuroendocrine effects.
Excitation-induced cell damage and β2-adrenoceptor agonist stimulated force recovery in rat skeletal muscle
Authors: Mikkelsen Ulla Ramer , Gissel Hanne , Fredsted Anne , Clausen Torben
Published: October 2005

Intensive exercise leads to a loss of force, which may be long lasting and associated with muscle cell damage. To simulate this impairment and to develop means of compensating the loss of force, extensor digitorum longus muscles from 4-wk-old rats were fatigued using intermittent 40-Hz stimulation (10 s on, 30 s off). After stimulation, force recovery, cell membrane leakage, and membrane potential were followed for 240 min. The 30–60 min of stimulation reduced tetanic force to ∼10% of the prefatigue level, followed by a spontaneous recovery to ∼20% in 120–240 min. Loss of force was associated with a decrease in K+ content, gain of Na+ and Ca2+ content, leakage of the intracellular enzyme lactic acid dehydrogenase (10-fold increase), and depolarization (13 mV). Stimulation of the Na+-K+ pump with either the β2-adrenoceptor agonist salbutamol, epinephrine, rat calcitonin gene-related peptide (rCGRP), or dibutyryl cAMP improved force recovery by 40–90%. The β-blocker propranolol abolished the effect of epinephrine on force recovery but not that of CGRP. Both spontaneous and salbutamol-induced force recovery were prevented by ouabain. The salbutamol-induced force recovery was associated with repolarization of the membrane potential (12 mV) to the level measured in unfatigued muscles. In conclusion, in muscles exposed to fatiguing stimulation leading to a considerable loss of force, cell leakage, and depolarization, stimulation of the Na+-K+ pump induces repolarization and improves force recovery, possibly due to the electrogenic action of the Na+-K+ pump. This mechanism may be important for the restoration of muscle function after intense exercise.
Effects of load, and duration, of duodenal lipid on antropyloroduodenal motility, plasma CCK and PYY, and energy intake in healthy men
Authors: Pilichiewicz Amelia N. , Little Tanya J. , Brennan Ixchel M. , Meyer James H. , Wishart Judith M. , Otto Bärbel , Horowitz Michael , Feinle-Bisset Christine
Published: October 2005

Enterally administered lipid modulates antropyloroduodenal motility, gut hormone release, appetite, and energy intake. We hypothesized that these effects would be dependent on both the load, and duration, of small intestinal exposure to lipid. Eleven healthy men were studied on four occasions in a double-blind, randomized, fashion. Antropyloroduodenal motility, plasma CCK and peptide YY (PYY) concentrations, and appetite perceptions were measured during intraduodenal infusion of lipid (Intralipid) at 1) 1.33 kcal/min for 50 min, 2) 4 kcal/min for 50 min, and 3) 1.33 kcal/min for 150 min, or 4) saline for 150 min. Immediately after the infusions, energy intake was quantified. Pressure wave sequences (PWSs) were suppressed, and basal pyloric pressure, isolated pyloric pressure waves (IPPWs), plasma CCK and PYY stimulated (all P < 0.05), during the first 50 min of lipid infusion, in a load-dependent fashion. The effect of the 4 kcal/min infusion was sustained so that the suppression of antral pressure waves (PWs) and PWSs and increase in PYY remained evident after cessation of the infusion (all P < 0.05). The prolonged lipid infusion (1.33 kcal/min for 150 min) suppressed antral PWs, stimulated CCK and PYY and basal pyloric pressure (all P < 0.05), and tended to stimulate IPPWs when compared with saline throughout the entire infusion period. There was no significant effect of any of the lipid infusions on appetite or energy intake, although nausea was slightly higher ( P < 0.05) with the 4 kcal/min infusion. In conclusion, both the load, and duration, of small intestinal lipid influence antropyloroduodenal motility and patterns of CCK and PYY release.
Examining axial diffusion of nitric oxide in the lungs using heliox and breath hold
Authors: Shin Hye-Won , Condorelli Peter , George Steven C.
Published: October 2005

Exhaled nitric oxide (NO) is highly dependent on exhalation flow; thus exchange dynamics of NO have been described by multicompartment models and a series of flow-independent parameters that describe airway and alveolar exchange. Because the flow-independent NO airway parameters characterize features of the airway tissue (e.g., wall concentration), they should also be independent of the physical properties of the insufflating gas. We measured the total mass of NO exhaled ( AI,II) from the airways after five different breath-hold times (5–30 s) in healthy adults (21–38 yr, n = 9) using air and heliox as the insufflating gas, and then modeled AI,IIas a function of breath-hold time to determine airway NO exchange parameters. Increasing breath-hold time results in an increase in AI,IIfor both air and heliox, but AI,IIis reduced by a mean (SD) of 31% (SD 6) ( P < 0.04) in the presence of heliox, independent of breath-hold time. However, mean (SD) values (air, heliox) for the airway wall diffusing capacity [3.70 (SD 4.18), 3.56 pl·s−1·ppb−1(SD 3.20)], the airway wall concentration [1,439 (SD 487), 1,503 ppb (SD 644>)], and the maximum airway wall flux [4,156 (SD 2,502), 4,412 pl/s (SD 2,906)] using a single-path trumpet-shaped airway model that considers axial diffusion were independent of the insufflating gas ( P > 0.55). We conclude that a single-path trumpet model that considers axial diffusion captures the essential features of airway wall NO exchange and confirm earlier reports that the airway wall concentration in healthy adults exceeds 1 ppm and thus approaches physiological concentrations capable of modulating smooth muscle tone.
Pulmonary ischemia induces lung remodeling and angiogenesis
Authors: Wagner Elizabeth M. , Petrache Irina , Schofield Brian , Mitzner Wayne
Published: October 2005

Cellular remodeling during angiogenesis in the lung is poorly described. Furthermore, it is the systemic vasculature of the lung and surrounding the lung that is proangiogenic when the pulmonary circulation becomes impaired. In a mouse model of chronic pulmonary thromboembolism, after left pulmonary artery ligation (LPAL), the intercostal vasculature, in proximity to the ischemic lung, proliferates and invades the lung ( 12 ). In the present study, we performed a detailed investigation of the kinetics of remodeling using histological sections of the left lung of C57Bl/6J mice after LPAL (4 h to 20 days) or after sham surgery. New vessels were seen within the thickened visceral pleura 4 days after LPAL predominantly in the upper portion of the left lung. Connections between new vessels within the pleura and pulmonary capillaries were clearly discerned by 7 days after LPAL. The visceral pleura and the lung parenchyma showed intense tissue remodeling, as evidenced by markedly elevated levels of both proliferating cell nuclear antigen and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive cells. Rapidly dividing cells were predominantly macrophages and type II pneumocytes. The increased apoptotic activity was further quantified by caspase-3 activity, which showed a sixfold increase relative to naive lungs, by 24 h after LPAL. Because sham surgeries had little effect on measured parameters, we conclude that both thoracic wound healing and pulmonary ischemia are required for systemic neovascularization.
Low-intensity exercise training during doxorubicin treatment protects against cardiotoxicity
Authors: Chicco Adam J. , Hydock David S. , Schneider Carole M. , Hayward Reid
Published: October 2005

Doxorubicin (Dox) is a highly effective antineoplastic antibiotic associated with a dose-limiting cardiotoxicity that may result in irreversible cardiomyopathy and heart failure. The purpose of this study was to examine the effects of low-intensity exercise training (LIET) during the course of Dox treatment on cardiac function, myosin heavy chain expression, oxidative stress, and apoptosis activation following treatment. Male Sprague-Dawley rats either remained sedentary or were exercise trained on a motorized treadmill at 15 m/min, 20 min/day, 5 days/wk (Monday through Friday) for 2 wk. During the same 2-wk period, Dox (2.5 mg/kg) or saline was administered intraperitoneally to sedentary and exercised rats 3 days/wk (Monday, Wednesday, Friday) 1–2 h following the exercise training sessions (cumulative Dox dose: 15 mg/kg). Five days following the final injections, hearts were isolated for determination of left ventricular (LV) function, lipid peroxidation, antioxidant enzyme protein expression, 72-kDa heat shock protein expression, caspase-3 activity, and myosin heavy chain isoform expression. Dox treatment significantly impaired LV function and increased caspase-3 activity in sedentary animals ( P < 0.05). LIET attenuated the LV dysfunction and apoptotic signal activation induced by Dox treatment and increased glutathione peroxidase expression, but it had no significant effect on lipid peroxidation, protein expression of myosin heavy chain isoforms, 72-kDa heat shock protein, or superoxide dismutase isoforms. In conclusion, our data suggest that LIET applied during chronic Dox treatment protects against cardiac dysfunction following treatment, possibly by enhancing antioxidant defenses and inhibiting apoptosis.
Cardiovascular effects of epinephrine during rewarming from hypothermia in an intact animal model
Authors: Kondratiev T. V. , Myhre E. S. P. , Simonsen Ø. , Nymark T.-B. , Tveita T.
Published: October 2005

Rewarming from accidental hypothermia is often complicated by “rewarming shock,” characterized by low cardiac output (CO) and a sudden fall in peripheral arterial pressure. In this study, we tested whether epinephrine (Epi) is able to prevent rewarming shock when given intravenously during rewarming from experimental hypothermia in doses tested to elevate CO and induce vasodilation, or lack of vasodilation, during normothermia. A rat model designed for circulatory studies during experimental hypothermia and rewarming was used. A total of six groups of animals were used: normothermic groups 1, 2, and 3 for dose-finding studies, and hypothermic groups 4, 5, and 6. At 20 and 24°C during rewarming, group 4 (low-dose Epi) and group 5 (high-dose Epi) received bolus injections of 0.1 and 1.0 μg Epi, respectively. At 28°C, Epi infusion was started in groups 4 and 5 with 0.125 and 1.25 μg/min, respectively. Group 6 served as saline control. After rewarming, both CO and stroke volume were restored in group 4, in contrast to groups 5 and 6, in which both CO and stroke volume remained significantly reduced (30%). Total peripheral resistance was significantly higher in group 5 during rewarming from 24 to 34°C, compared with groups 4 and 6. This study shows that, in contrast to normothermic conditions, Epi infused during hypothermia induces vasoconstriction rather than vasodilation combined with lack of CO elevation. The apparent dissociation between myocardial and vascular responses to Epi at low temperatures may be related to hypothermia-induced myocardial failure and changes in temperature-dependent adrenoreceptor affinity.
The influence of radial RBC distribution, blood velocity profiles, and glycocalyx on coupled NO/O2transport
Authors: Chen Xuewen , Jaron Dov , Barbee Kenneth A. , Buerk Donald G.
Published: October 2005

The purpose of this investigation was to study the effect of the presence of red blood cells (RBCs) in the plasma layer near the arteriole wall on nitric oxide (NO) and oxygen (O2) transport. To this end, we extended a coupled NO and O2diffusion-reaction model in the arteriole, developed by our group, to include the effect of the presence of RBCs in the plasma layer and the effect of convection. Two blood flow velocity profiles (plug and parabolic) were tested. The average hematocrit in the bloodstream was assumed to be constant in the central core and decreasing to zero in the boundary layer next to the endothelial surface layer. The effect of the presence or absence of RBCs near the endothelium was studied while varying the endothelial surface layer and boundary layer thickness. With RBCs present in the boundary layer, the model predicts that 1) NO decreases significantly in the endothelium and vascular wall; 2) there is a very small increase in endothelial and vascular wall Po2; 3) scavenging of NO by hemoglobin decreases with increasing thickness of the boundary layer; 4) the shape of the velocity profile influences both NO and Po2gradients in the bloodstream; and 5) the presence of RBCs in the boundary layer near the endothelium has a much larger effect on NO than on O2transport.
Effects of obesity and sex on the energetic cost and preferred speed of walking
Authors: Browning Raymond C. , Baker Emily A. , Herron Jessica A. , Kram Rodger
Published: October 2005

The metabolic energy cost of walking is determined, to a large degree, by body mass, but it is not clear how body composition and mass distribution influence this cost. We tested the hypothesis that walking would be most expensive for obese women compared with obese men and normal-weight women and men. Furthermore, we hypothesized that for all groups, preferred walking speed would correspond to the speed that minimized the gross energy cost per distance. We measured body composition, maximal oxygen consumption, and preferred walking speed of 39 (19 class II obese, 20 normal weight) women and men. We also measured oxygen consumption and carbon dioxide production while the subjects walked on a level treadmill at six speeds (0.50–1.75 m/s). Both obesity and sex affected the net metabolic rate (W/kg) of walking. Net metabolic rates of obese subjects were only ∼10% greater (per kg) than for normal-weight subjects, and net metabolic rates for women were ∼10% greater than for men. The increase in net metabolic rate at faster walking speeds was greatest in obese women compared with the other groups. Preferred walking speed was not different across groups (1.42 m/s) and was near the speed that minimized gross energy cost per distance. Surprisingly, mass distribution (thigh mass/body mass) was not related to net metabolic rate, but body composition (% fat) was ( r2= 0.43). Detailed biomechanical studies of walking are needed to investigate whether obese individuals adopt novel energy saving mechanisms during walking.
Upregulation of Proinflammatory Proteins Through NF-κB Pathway by Shed Membrane Microparticles Results in Vascular Hyporeactivity
Authors: Tesse Angela , Martínez M. Carmen , Hugel Bénédicte , Chalupsky Karel , Muller Christian D. , Meziani Ferhat , Mitolo-Chieppa Delia , Freyssinet Jean-Marie , Andriantsitohaina Ramaroson
Published: October 2005

Objective—Microparticles are membrane vesicles with procoagulant and proinflammatory properties released during cell activation, including apoptosis. The present study was designed in dissecting the effects evoked by microparticles on vascular reactivity.

Methods and Results—Microparticles from either apoptotic T lymphocytic cells or from plasma of diabetic patients with vascular complications induced vascular hyporeactivity in response to vasoconstrictor agents in mouse aorta. Hyporeactivity was reversed by nitric oxide (NO) synthase plus cyclooxygenase-2 inhibitors, and associated with an increased production of vasodilatory products such as NO and prostacyclin. Microparticles induced an upregulation of proinflammatory protein expressions, inducible NO-synthase and cyclooxygenase-2, mainly in the medial layer of the vessels as evidenced by immunochemical staining. In addition, microparticles evoke NF-κB activation probably through the interaction with the Fas/Fas Ligand pathway. Finally, in vivo treatment of mice with lymphocyte-derived MPs induces vascular hyporeactivity, which was reversed by the combination of NO and cyclooxygenase-2 inhibitors.

Conclusion—These data provide a rationale to explain the paracrine role of microparticles as vectors of transcellular exchange of message in promoting vascular dysfunction during inflammatory diseases.
Fibrinogen Contains Cryptic PAI-1 Binding Sites That Are Exposed on Binding to Solid Surfaces or Limited Proteolysis
Authors: Smolarczyk Katarzyna , Boncela Joanna , Szymanski Jacek , Gils Ann , Cierniewski Czeslaw S.
Published: October 2005

Objective—

In this work, we identified the fibrinogen sequence that on exposure serves as the primary binding site for functionally active PAI-1 and to a lesser extent for its latent form. In contrast, this site only weakly interacts with PAI-1 substrate.

Methods and Results—

The binding site is located in the N-terminal α (20-88) segment of fibrinogen, in the region exposed on (1) adsorption of fibrinogen to solid surfaces; (2) the release of fibrinopeptide A during thrombin conversion of fibrinogen to fibrin; and (3) plasmin degradation of fibrinogen. This region was first identified by the yeast 2-hybrid system, then its binding characteristics were evaluated using the recombinant α(16-120) fragment and its shorter version, the α(20-88) fragment, in a solid phase binding assay and plasmon surface resonance measurements. Because fibrinogen fragment E does not bind PAI-1, it suggests that sequences of Aα chain interacting with PAI-1 are located in the N-terminal part of the α(20-88) segment.

Conclusions—

Therefore, PAI-1 directly bound to the α(20-88) and thus concentrated in fibrinogen/fibrin, particularly at sites of injury and inflammation, may account for the recent observations that both its active and latent forms stimulate cell migration and wound healing.
Effect of Nuclear Actin on Endothelial Nitric Oxide Synthase Expression
Authors: Ou Hesheng , Shen Ying H. , Utama Budi , Wang Jian , Wang Xinwen , Coselli Joseph , Wang Xing Li
Published: October 2005

Background—

Previously, we showed that the 27nt repeat polymorphism in endothelial nitric oxide synthase (eNOS) intron 4 was associated with altered eNOS mRNA and protein levels, nitric oxide (NO) production and vascular disease risk; the 27-nt repeats had a
cis
-acting role in eNOS promoter function. In the present study, we investigated nuclear protein that binds the 27nt repeat and mediates eNOS expression.

Methods and Results—

Using 5′-biotin-labeled 27nt DNA duplex and streptavidin–agarose beads pull-down assay and mass spectrometry, we identified that nuclear β-actin was one of the major 27nt binding proteins. Using the pGL3 reporter vectors containing the 5×27nt repeats as an enhancer in an in vitro transcription assay, we found that exogenous β-actin significantly increased reporter gene transcription efficiency. The β-actin’s upregulating effect was compromised when exogenous 27nt RNA duplex was added. Furthermore, the eNOS expression was reduced when β-actin gene was silenced by specific siRNA, and actin overexpression upregulated eNOS expression >3-fold.

Conclusion—

Our data demonstrate that β-actin as a transcription factor stimulates eNOS expression; and the transcriptional effect appears to be 27nt-dependent. Our findings represent a novel molecular mechanism regulating eNOS expression, which could potentially lead to discoveries of eNOS specific pharmaceutical agents, eg, active peptides, with clinical applications.
Mobilization of Bone Marrow–Derived Cells Enhances the Angiogenic Response to Hypoxia Without Transdifferentiation Into Endothelial Cells
Authors: O’Neill Thomas J. , Wamhoff Brian R. , Owens Gary K. , Skalak Thomas C.
Published: October 2005

Bone marrow–derived cells (BMCs) have been implicated as a modifiers of vascular growth either directly by transdifferentiation into endothelial cells (ECs) or indirectly through growth factor release. To examine these possibilities under physiological conditions, we developed a model of hypoxia-mediated angiogenesis in the mouse spinotrapezius muscle. This allows whole-mount analysis; therefore, the morphology and location of BMCs within the vascular network may be observed along with differentiation markers. We exposed bone marrow transplant chimeric mice to hypoxia and treated a subset with granulocyte macrophage colony–stimulating factor. Exposure to hypoxia caused an 13% increase in capillary density relative to control. Hypoxia did not increase the overall number of muscle-resident BMCs, but did increase the number of rounded BMCs by 25%. There was no discernable BMC contribution to the endothelium, although some BMCs assumed a pericyte morphology around capillaries. Granulocyte macrophage colony–stimulating factor treatment further increased the number of round BMCs within the muscle and caused a 23% increase in angiogenesis. The results of this study suggest a potentially beneficial action of BMCs during hypoxia through paracrine release of growth factors but not transdifferentiation into ECs.
Nedd9 Protein, a Cas-L Homologue, Is Upregulated After Transient Global Ischemia in Rats
Authors: Sasaki Takahiro , Iwata Satoshi , Okano Hirotaka James , Urasaki Yasuyo , Hamada Junichi , Tanaka Hirotoshi , Dang Nam H. , Okano Hideyuki , Morimoto Chikao
Published: October 2005

Background and Purpose—

Some proteins involved in self-repair after stroke in the adult brain are primarily expressed during embryonic development and strongly down-regulated during the early postnatal phase. Neuronal precursor cell-expressed, developmentally down-regulated gene (Nedd) 9 was recognized to be identical to Crk-associated substrate lymphocyte type (Cas-L), a docking protein that associates with a variety of signaling molecules, such as focal adhesion kinase (FAK), proline-rich tyrosine kinase 2 (Pyk2), and Crk. We investigated the involvement of these proteins in the pathophysiology of global cerebral ischemia.

Methods—

The mouse Cas-L/Nedd9 cDNAs were cloned. The expression and function of Cas-L/Nedd9 protein in the pathogenesis of global ischemia in rats was investigated by RT-PCR, Western blot analysis, and immunohistochemistry. The neurite outgrowth of the transfectants of Nedd9 deletion mutants in PC-12 cells was also assessed to clarify the function of the Nedd9 protein.

Results—

Nedd9 was a splicing variant of Cas-L and was selectively induced in neurons of the cerebral cortex and hippocampus 1 to 14 days after the ischemia. Induced Nedd9 protein was tyrosine phosphorylated and was bound to FAK in dendrite and soma of neurons after the ischemia. Finally, it was demonstrated that Nedd9 promoted neurite outgrowth of PC-12 cells.

Conclusions—

Our study may support the potential of Nedd9 for participation in the differentiation of neurons after global ischemia in rats.
Silent Cerebral Ischemia Detected With Diffusion-Weighted Imaging in Patients Treated With Protected and Unprotected Carotid Artery Stenting
Authors: Cosottini Mirco , Michelassi Maria Chiara , Puglioli Michele , Lazzarotti Guido , Orlandi Giovanni , Marconi Franco , Parenti Giuliano , Bartolozzi Carlo
Published: October 2005

Background and Purpose—

Percutaneous transluminal angioplasty with stent (CAS) is an alternative method to endarterectomy in the revascularization of carotid artery stenosis. Protected CAS is currently used to prevent distal embolization. Diffusion-weighted MRI (DWI) is the most sensitive tool to evaluate silent cerebral ischemia. The purpose of this research was to assess the incidence of cerebral embolic lesions during CAS and to evaluate whether cerebral protection devices can reduce the number of silent cerebral ischemia with respect to unprotected CAS.

Methods—

Fifty-two patients with high-grade internal stenosis underwent CAS; 30 patients (group a) were treated with a cerebral protection device, and 22 (group b) were treated without it. All of the patients were evaluated preoperatively and postoperatively with fluid-attenuated inversion recovery and DWI sequences to depict the number of new embolic silent cerebral lesions.

Results—

Embolic silent cerebral lesions occurred in 30% of CAS. Cerebral protection devices reduce the number of new lesions significantly reducing the consistent lesions ipsilateral to the treated vessel. Inconsistent lesions do not differ in both groups of patients. Clinical, radiological, and procedural variables do not correlate with the appearance of new cerebral lesions.

Conclusions—

Embolic cerebral lesions detected with DWI are more frequent with unprotected CAS, although they are present also with the use of cerebral protection devices. Probably a part of silent cerebral lesions arise from the procedural maneuver in the aortic arch.
Electrocardiographic Left Atrial Abnormalities and Risk of Ischemic Stroke
Authors: Kohsaka Shun , Sciacca Robert R. , Sugioka Kenichi , Sacco Ralph L. , Homma Shunichi , Di Tullio Marco R.
Published: October 2005

Background and Purpose—

We evaluated the association between electrocardiographic left atrial abnormality (ECG-LAA) and ischemic stroke, especially whether ECG-LAA provides additional prognostic information to that provided by echocardiography.

Methods—

A population-based, case-control study included 146 patients with first ischemic stroke and 195 age-, gender-, and race/ethnicity-matched community control subjects. ECG-LAA was defined as either P-wave duration >120 ms or P-terminal force in precordial lead V
1
(PTFV
1
) >40 ms·mm.

Results—

PTFV
1
>40 ms·mm was associated with ischemic stroke after adjustment for other stroke risk factors (odds ratio [OR], 2.32; 95% CI, 1.29 to 4.18). The association remained significant after adding echocardiographic left atrial diameter to the model (OR, 2.31; 95% CI, 1.28 to 4.17). PTFV
1
was independently associated with stroke in patients in the upper half of echocardiographically determined left ventricular mass (adjusted OR, 4.5; 95% CI, 2.20 to 9.15) but not in those in the lower half (OR, 0.58; 95% CI, 0.20 to 1.65;
P
=0.0008).

Conclusions—

ECG-LAA can supplement 2D echocardiography in assessing the risk of ischemic stroke, especially in subjects with increased left ventricular mass.
Incidence of Recurrent Subarachnoid Hemorrhage After Clipping for Ruptured Intracranial Aneurysms
Authors: Wermer Marieke J.H. , Greebe Paut , Algra Ale , Rinkel Gabriël J.E.
Published: October 2005

Background and Purpose—

Because intracranial aneurysms develop during life, patients with subarachnoid hemorrhage (SAH) and successfully occluded aneurysms are at risk for a recurrence. We studied the incidence of and risk factors for recurrent SAH in patients who regained independence after SAH and in whom all aneurysms were occluded by means of clipping.

Methods—

From a cohort of patients with SAH admitted between 1985 and 2001, we included those patients who were discharged home or to a rehabilitation facility. We interviewed these patients about new episodes of SAH. We retrieved all medical records and radiographs in case of reported recurrences. If patients had died, we retrieved the cause of death. We analyzed the incidence of and risk factors for recurrent SAH by Kaplan-Meier curves and Cox regression analysis.

Results—

Of 752 patients with 6016 follow-up years (mean follow up 8.0 years), 18 had a recurrence. In the first 10 years after the initial SAH, the cumulative incidence of recurrent SAH was 3.2% (95% confidence interval [CI], 1.5% to 4.9%) and the incidence rate 286 of 100 000 patient-years (95% CI, 160 to 472 per 100 000). Risk factors were smoking (hazard ratio [HR], 6.5; 95% CI, 1.7 to 24.0), age (HR, 0.5 per 10 years; 95% CI, 0.3 to 0.8) and multiple aneurysms at the time of the initial SAH (HR, 5.5; 95% CI, 2.2 to 14.1).

Conclusions—

After SAH, the incidence of a recurrence within the first 10 years is 22 (12 to 38) times higher than expected in populations with comparable age and sex. Whether this increased risk justifies screening for recurrent aneurysms in patients with a history of SAH requires further study.
Thrombolysis Beyond the Guidelines
Authors: Topakian Raffi , Gruber Franz , Fellner Franz A. , Haring Hans-Peter , Aichner Franz T.
Published: October 2005

Background and Purpose—

We report the first case of 2 intravenous thrombolysis treatments within 90 hours in a patient with early recurrent stroke.

Summary of Review—

A 50-year-old man had improved significantly after intravenous thrombolysis for acute stroke. On the fourth day, he deteriorated dramatically because of recurrent stroke. Evidence of vessel reocclusion and profound perfusion/diffusion mismatch constituted the rationale for a second thrombolysis treatment, which resulted in vessel recanalization and significant neurologic improvement.

Conclusion—

The pathophysiological information obtained by multimodal magnetic resonance imaging may suit as a brain clock when repeat thrombolysis treatment is considered for early recurrent stroke.
Cardiac Support Device Modifies Left Ventricular Geometry and Myocardial Structure After Myocardial Infarction
Authors: Blom Aaron S. , Mukherjee Rupak , Pilla James J. , Lowry Abigail S. , Yarbrough William M. , Mingoia Joseph T. , Hendrick Jennifer W. , Stroud Robert E. , McLean Julie E. , Affuso John , Gorman Robert C. , Gorman Joseph H. , Acker Michael A. , Spinale Francis G.
Published: October 2005

Background—

Whether mechanical restraint of the left ventricle (LV) can influence remodeling after myocardial infarction (MI) remains poorly understood. This study surgically placed a cardiac support device (CSD) over the entire LV and examined LV and myocyte geometry and function after MI.

Methods and Results—

Post-MI sheep (35 to 45 kg; MI size, 23±2%) were randomized to placement of the CorCap CSD (Acorn Cardiovascular, Inc) (MI+CSD; n=6) or remained untreated (MI only; n=5). Uninstrumented sheep (n=10) served as controls. At 3 months after MI, LV end-diastolic volume (by MRI) was increased in the MI only group compared with controls (98±8 versus 43±4 mL;
P
<0.05). In the MI+CSD group, LV end-diastolic volume was lower than MI only values (56±7 mL;
P
<0.05) but remained higher than controls (
P
<0.05). Isolated LV myocyte shortening velocity was reduced by 35% from control values (
P
<0.05) in both MI groups. LV myocyte β-adrenergic response was reduced with MI but normalized in the MI+CSD group. LV myocyte length increased in the MI group and was reduced in the MI+CSD group. Relative collagen content was increased and matrix metalloproteinase-9 was decreased within the MI border region of the CSD group.

Conclusions—

A CSD beneficially modified LV and myocyte remodeling after MI through both cellular and extracellular mechanisms. These findings provide evidence that nonpharmacological strategies can interrupt adverse LV remodeling after MI.
Atrial Fibrillation Increases Production of Superoxide by the Left Atrium and Left Atrial Appendage
Authors: Dudley Samuel C. , Hoch Nyssa E. , McCann Louise A. , Honeycutt Clegg , Diamandopoulos Laura , Fukai Tohru , Harrison David G. , Dikalov Sergey I. , Langberg Jonathan
Published: October 2005

Background—

Atrial fibrillation (AF) is associated with an increased risk of stroke due almost exclusively to emboli from left atrial appendage (LAA) thrombi. Recently, we reported that AF was associated with endocardial dysfunction, limited to the left atrium (LA) and LAA and manifest as reduced nitric oxide (NO
·
) production and increased expression of plasminogen activator inhibitor-1. We hypothesized that reduced LAA NO
·
levels observed in AF may be associated with increased superoxide (O
2
·−
) production.

Methods and Results—

After a week of AF induced by rapid atrial pacing in pigs, O
2
·−
production from acutely isolated heart tissue was measured by 2 independent techniques, electron spin resonance and superoxide dismutase–inhibitable cytochrome C reduction assays. Compared with control animals with equivalent ventricular heart rates, basal O
2
·−
production was increased 2.7-fold (
P
<0.01) and 3.0-fold (
P
<0.02) in the LA and LAA, respectively. A similar 3.0-fold (
P
<0.01) increase in LAA O
2
·−
production was observed using a cytochrome C reduction assay. The increases could not be explained by changes in atrial total superoxide dismutase activity. Addition of either apocyanin or oxypurinol reduced LAA O
2
·−
, implying that NADPH and xanthine oxidases both contributed to increased O
2
·−
production in AF. Enzyme assays of atrial tissue homogenates confirmed increases in LAA NAD(P)H oxidase (
P
=0.04) and xanthine oxidase (
P
=0.01) activities. Although there were no changes in expression of the NADPH oxidase subunits, the increase in superoxide production was accompanied by an increase in GTP-loaded Rac1, an activator of the NADPH oxidase.

Conclusions—

AF increased O
2
·−
production in both the LA and LAA. Increased NAD(P)H oxidase and xanthine oxidase activities contributed to the observed increase in LAA O
2
·−
production. This increase in O
2
·−
and its reactive metabolites may contribute to the pathological consequences of AF such as thrombosis, inflammation, and tissue remodeling.
Glycogen Synthase Kinase-3 Mediates Endothelial Cell Activation by Tumor Necrosis Factor-α
Authors: Eto Masato , Kouroedov Alexei , Cosentino Francesco , Lüscher Thomas F.
Published: October 2005

Background—

Endothelial cell transformation to a thrombogenic and inflammatory phenotype plays an important role in the pathogenesis of atherothrombosis, but the responsible signaling pathways remain to be elucidated. This study was designed to investigate the regulatory role of glycogen synthase kinase-3 (GSK-3) in tissue factor (TF) and vascular cell adhesion molecule (VCAM)-1 expression in tumor necrosis factor (TNF)-α–stimulated endothelial cells.

Methods and Results—

In human endothelial cells, TNF-α as well as thrombin induced rapid and transient dephosphorylation and hence, activation of GSK-3. A GSK-3 inhibitor, LiCl, suppressed TNF-α– and thrombin-induced TF and VCAM-1 expression, whereas NaCl had no effect. A specific GSK-3 inhibitor, TDZD-8, mimicked the inhibitory effects of lithium. GSK-3 inhibition also significantly suppressed the TNF-α–induced increase in TF activity and VCAM-1 cell-surface expression. The luciferase reporter system demonstrated that regulation of TF and VCAM-1 expression by GSK-3 was mediated at the transcriptional level. The TNF-α–induced increase in nuclear factor (NF)-κB DNA-binding activity was significantly suppressed by TDZD-8. TDZD-8 completely prevented the TNF-α–induced inhibitor of NF-κB (IκB)-α degradation but had no effect on IκB-kinase-β phosphorylation.

Conclusions—

GSK-3 regulates TNF-α–induced IκB-α degradation and NF-κB activation independent of IκB-kinase-β and subsequent induction of TF and VCAM-1 expression in human endothelial cells. This study provides the experimental basis for a novel strategy of using GSK-3 inhibition to treat atherothrombotic vascular disease.
Involvement of Tumor Necrosis Factor-α in the Development of T Cell–Dependent Aortitis in Interleukin-1 Receptor Antagonist–Deficient Mice
Authors: Matsuki Taizo , Isoda Kikuo , Horai Reiko , Nakajima Akiko , Aizawa Yoshifusa , Suzuki Kazuo , Ohsuzu Fumitaka , Iwakura Yoichiro
Published: October 2005

Background—

Interleukin-1 receptor antagonist–deficient (IL-1Ra
−/−
) mice on the BALB/c background spontaneously develop inflammatory arthropathy that resembles rheumatoid arthritis in humans. These mice also frequently develop aortitis at the root of the aorta, but the mechanism underlying the development of this disease has not been completely elucidated.

Methods and Results—

Using IL-1Ra
−/−
mice (backcrossed 8 generations to the BALB/c background) and wild-type mice, we studied the histopathology and examined the immunologic mechanisms involved in the development of aortic inflammation by cell transplantation experiments. Half of the IL-1Ra
−/−
mice developed aortitis at the root of the aorta, with massive infiltration of macrophages and monocytes and loss of elastic lamellae in the aortic media. Left ventricular hypertrophy and mild aortic stenosis were also shown by transthoracic echocardiography. Transplantation of T cells from IL-1Ra
−/−
mice induced aortitis in recipient nu/nu mice. Bone marrow cell transplants from IL-1Ra
−/−
mice also induced aortitis in irradiated wild-type recipient mice. Furthermore, tumor necrosis factor (TNF)-α deficiency completely suppressed the development of aortitis in IL-1Ra
−/−
mice, whereas IL-6 deficiency did not affect pathology.

Conclusions—

These observations suggest that IL-1Ra deficiency in T cells activates them excessively, resulting in the development of aortitis in IL-1Ra
−/−
mice in a TNF-α–dependent manner.