bluuebunny/crossref_metadata_2025 huggingface dataset:
Regional differences in cholinergic regulation of potassium current in feline esophageal circular smooth muscle
Authors: Muinuddin Ahmad , Naqvi Khurram , Sheu Laura , Gaisano Herbert Y. , Diamant Nicholas E.
Published: February 2005

Potassium channels are important contributors to membrane excitability in smooth muscles. There are regional differences in resting membrane potential and K+-channel density along the length of the feline circular smooth muscle esophagus. The aim of this study was to assess responses of K+-channel currents to cholinergic (ACh) stimulation along the length of the feline circular smooth muscle esophageal body. Perforated patch-clamp technique assessed K+-channel responses to ACh stimulation in isolated smooth muscle cells from the circular muscle layer of the esophageal body at 2 (distal)- and 4-cm (proximal) sites above the lower esophageal sphincter. Western immunoblots assessed ion channel and receptor expression. ACh stimulation produced a transient increase in outward current followed by inhibition of spontaneous transient outward currents. These ACh-induced currents were abolished by blockers of large-conductance Ca2+-dependent K+ channels (BKCa). Distal cells demonstrated a greater peak current density in outward current than cells from the proximal region and a longer-lasting outward current increase. These responses were abolished by atropine and the specific M3 receptor antagonist 4-DAMP but not the M1 receptor antagonist pirenzipine or the M2 receptor antagonist methoctramine. BKCa expression along the smooth muscle esophagus was similar, but M3 receptor expression was greater in the distal region. Therefore, ACh can differentially activate a potassium channel (BKCa) current along the smooth muscle esophagus. This activation probably occurs through release of intracellular calcium via an M3 pathway and has the potential to modulate the timing and amplitude of peristaltic contraction along the esophagus.
Role of USF1 and USF2 as potential repressor proteins for human intestinal monocarboxylate transporter 1 promoter
Authors: Hadjiagapiou Christos , Borthakur Alip , Dahdal Refka Y. , Gill Ravinder K. , Malakooti Jaleh , Ramaswamy Krishnamurthy , Dudeja Pradeep K.
Published: February 2005

Butyrate, a short-chain fatty acid, is the major energy fuel for the colonocytes. We have previously reported that monocarboxylate transporter isoform 1 (MCT1) mediates uptake of butyrate by human colonic Caco-2 cells. To better understand the mechanisms of MCT1 expression and regulation in the human intestine, we examined the activity and regulation of MCT1 promoter in Caco-2 cells. The transcription initiation site in the MCT1 promoter was identified as a guanine nucleotide 281 bp upstream from the translation initiation site and is surrounded by a guanine-cytosine-rich area. The promoter was found to be highly active when transfected into Caco-2 cells, and its activity decreased with deletions at its 5′-end. Gel mobility shift experiments showed binding of the transcription factors upstream stimulatory factor (USF)1 and 2 to the site −114 to −119 of the MCT1 promoter. With the use of site-directed mutagenesis and promoter activity in Caco-2 cells, the USF proteins appeared to have a repressor role on the MCT1 promoter, which was further confirmed by cotransfecting expression vectors encoding USF1 and 2 in Caco-2 cells and determining endogenous MCT1 expression in USF2 overexpressed cells. The two potential SP1 binding sites found in the same region of the promoter were found not to be involved in its regulation.
Acute colitis induction by oil of mustard results in later development of an IBS-like accelerated upper GI transit in mice
Authors: Kimball Edward S. , Palmer Jeffrey M. , D'Andrea Michael R. , Hornby Pamela J. , Wade Paul R.
Published: February 2005

Oil of mustard (OM) is a potent neuronal activator that promotes allodynia and hyperalgesia within minutes of application. In this study, OM was used to induce an acute colitis. We also investigated whether intracolonic OM-induced inflammation alters gastrointestinal (GI) function over a longer time frame as a model of postinflammatory irritable bowel syndrome (PI-IBS). Mice given a single administration of 0.5% OM developed a severe colitis that peaked at day 3, was reduced at day 7, and was absent by day 14. At the peak response, there was body weight loss, colon shrinkage, thickening and weight increases, distension of the proximal colon, and diarrhea. Macroscopic inspection of the distal colon revealed a discontinuous pattern of inflammatory damage and occasional transmural ulceration. Histological examination showed loss of epithelium, an inflammatory infiltrate, destruction of mucosal architecture, edema, and loss of circular smooth muscle architecture. OM administration increased transit of a carmine dye bolus from 58% of the total length of the upper GI tract in untreated age-matched controls to as high as 74% when tested at day 28 post-OM. Mice in the latter group demonstrated a significantly more sensitive response to inhibition of upper GI transit by the μ-opioid receptor agonist loperamide compared with normal mice. OM induces a rapid, acute, and transient colitis and, in the longer term, functional changes in motility that are observed when there is no gross inflammation and thereby is a model of functional bowel disorders that mimic aspects of PI-IBS in humans.
Fructose-induced increases in neonatal rat intestinal fructose transport involve the PI3-kinase/Akt signaling pathway
Authors: Cui Xue-Lin , Schlesier Anna M. , Fisher Elda L. , Cerqueira Carla , Ferraris Ronaldo P.
Published: February 2005

Expression of rat glucose transporter-5 (GLUT5) is tightly regulated during development. Expression and activity are low throughout the suckling and weaning stages, but perfusion of the small intestinal lumen with fructose solutions during weaning precociously enhances GLUT5 activity and expression. Little is known, however, about the signal transduction pathways involved in the substrate-induced precocious GLUT5 development. We found that wortmannin and LY-294002, inhibitors of phosphatidylinositol 3-kinase (PI3-kinase) specifically inhibited the increase in fructose uptake rate and brush-border GLUT5 protein abundance but not GLUT5 mRNA abundance. Perfusion of EGF, an activator of PI3-kinase, also resulted in a marked wortmannin-inhibitable increase in fructose uptake. Perfusion of fructose for 4 h increased cytosolic immunostaining of phosphatidylinositol-3,4,5-triphosphate (PIP3), the primary product of PI3-kinase, mainly in the mid- to upper-villus regions in which the brush-border membrane also stained strongly with GLUT5. Perfusion of glucose for 4 h had little effect on fructose or glucose uptake and PIP3or GLUT5 staining. SH-5, an Akt inhibitor, prevented the increase in fructose uptake and GLUT5 protein induced by fructose solutions, and had no effect on glucose uptake. The PI3-kinase/Akt signaling pathway may be involved in the synthesis and/or recruitment to the brush border of GLUT5 transporters by luminal fructose in the small intestine of weaning rats. Increases in fructose transport during the critical weaning period when rats are shifting to a new diet may be modulated by several signaling pathways whose cross talk during development still needs to be elucidated.
Cross-talk along gastrointestinal tract during electrical stimulation: effects and mechanisms of gastric/colonic stimulation on rectal tone in dogs
Authors: Liu Shi , Wang Lijie , Chen J. D. Z.
Published: February 2005

Gastric electrical stimulation (GES) has been shown to alter motor and sensory functions of the stomach. However, its effects on other organs of the gut have rarely been investigated. The study was performed in 12 dogs implanted with two pairs of electrodes, one on the serosa of the stomach and the other on the colon. The study was composed of two experiments. Experiment 1 was designed to study the effects of GES on rectal tone and compliance in nine dogs compared with colonic electrical stimulation (CES). Rectal tone and compliance were assessed before and after GES or CES. Experiment 2 was performed to study the involvement of sympathetic pathway in 8 of the 12 dogs. The rectal tone was recorded for 30–40 min at baseline and 20 min after intravenous guanethidine. GES or CES was given for 20 min 20 min after the initiation of the infusion. It was found that both GES and CES reduced rectal tone with comparable potency. Rectal compliance was altered neither with GES, nor with CES. The inhibitory effect of GES but not CES on rectal tone was abolished by an adrenergic blockade, guanethidine. GES inhibited rectal tone with a comparable potency with CES but did not alter rectal compliance. The inhibitory effect of GES on rectal tone is mediated by the sympathetic pathway. It should be noted that electrical stimulation of one organ of the gut may have a beneficial or adverse effect on another organ of the gut.
d-Glucose upregulates adenosine transport in cultured human aortic smooth muscle cells
Authors: Leung George P. H. , Man Ricky Y. K. , Tse Chung-Ming
Published: February 2005

The etiology of the atherosclerosis that occurs in diabetes mellitus is unclear. Adenosine has been shown to inhibit growth of rat aortic smooth muscle cells. Nucleoside transporters play an integral role in adenosine function by regulating adenosine levels in the vicinity of adenosine receptors. Therefore, we studied the effect of 25 mM d-glucose, which mimics hyperglycemia of diabetes, on adenosine transport in cultured human aortic smooth muscle cells (HASMCs). Although RT-PCR demonstrated the presence of equilibrative nucleoside transporter-1 (ENT-1) and ENT-2 mRNA, functional studies revealed that adenosine transport in HASMCs was predominantly mediated by ENT-1 and inhibited by nitrobenzylmercaptopurine riboside (NBMPR, IC50 = 0.69 ± 0.05 nM). Adenosine transport in HASMCs was increased by >30% after treatment for 48 h with 25 mM d-glucose, but not with equimolar d-mannitol and l-glucose. Kinetic studies showed that d-glucose increased Vmax of adenosine transport without affecting Km. Similarly, d-glucose increased Bmax of high-affinity [3H]NBMPR binding, while the dissociation constant ( Kd) was not changed. Consistent with these observations, 25 mM d-glucose increased mRNA and protein expression of ENT-1. Treatment of serum-starved cells with the selective inhibitors of MAPK/ERK, PD-98059 (40 μM) and U-0126 (10 μM), abolished the effect of d-glucose on ENT-1. We conclude that d-glucose upregulates the protein and message expression and functional activity of ENT-1 in HASMCs, possibly via MAPK/ERK-dependent pathways. Pathologically, the increase in ENT-1 activity in diabetes may affect the availability of adenosine in the vicinity of adenosine receptors and, thus, alter vascular functions in diabetes.
Distensibility of the normal human lung circulation during exercise
Authors: Reeves John T. , Linehan John H. , Stenmark Kurt R.
Published: February 2005

Increasing pulmonary arterial (Ppa) and wedge (Pw) pressures at high flow (Q) during exercise could distend the thin-walled vessels. A mechanical descriptor of vascular distension, the distensibility (α, fractional diameter change/mmHg pressure), has been reported to be ∼0.02 for isolated large and small arteries, i.e., a 2% change in diameter per millimeter mercury pressure. In this review we used a pulmonary hemodynamic model to estimate α for data from exercising humans to determine whether interpretable results might be obtained. In 59 normal sea level subjects having published measurements of Ppa and Pw over a range of Q, we found values of α (0.02 ± 0.002) giving calculated Ppa, which matched measured Ppa to within 1.3 ± 0.1 (SE) mmHg. When subjects were exposed to chronic hypoxia ( n = 6, in Operation Everest II), α decreased (0.022 ± 0.002 vs. 0.008 ± 0.001, P < 0.05), but when subjects were exposed to acute hypoxia (Duke chamber study, n = 8), α did not decrease (0.014 ± 0.002 vs. 0.012 ± 0.002, P = not significant). Values of α tended to decrease with age in men >60 yr. Thus at rest and during exercise, normal values of α in young persons were similar to those measured in vitro, and the values decreased in chronic hypoxia and with aging where vascular remodeling or vascular wall stiffening was expected. We propose that the estimation of pulmonary vascular distensibility in humans may be a useful descriptor of pulmonary hemodynamics.
Ultrafine carbon particles induce interleukin-8 gene transcription and p38 MAPK activation in normal human bronchial epithelial cells
Authors: Kim Yu-Mee , Reed William , Lenz Anke G. , Jaspers Ilona , Silbajoris Robert , Nick Harry S. , Samet James M.
Published: February 2005

Epidemiological studies suggest that ultrafine particles contribute to particulate matter-induced adverse health effects. Interleukin (IL)-8 is an important proinflammatory cytokine in the human lung that is induced in respiratory cells exposed to a variety of environmental insults, including ambient air ultrafine particles. In this study, we examined the effect of a model ultrafine particle on IL-8 expression and the cellular mechanisms responsible for this event. Here, we report that carbonaceous ultrafine particles consisting of synthetic elemental carbon particles (UfCP) markedly increase the expression of IL-8 mRNA and protein in normal human bronchial epithelial (NHBE) cells. IL-8 promoter activity was increased by UfCP exposure in NHBE cells, indicating UfCP-induced IL-8 expression is transcriptionally regulated. IL-8 expression in NHBE is known to be regulated by nuclear factor (NF)-κB activation. However, UfCP did not induce inhibitory factor κBα degradation, NF-κB-DNA binding, or NF-κB-dependent promoter activity in NHBE cells, indicating that UfCP induces IL-8 expression through a mechanism that is independent of NF-κB activation. Additionally, we observed that UfCP exposure induces the phosphorylation and activation of p38 mitogen-activated protein kinase (MAPK) in a biphasic manner and that the inhibition of p38 MAPK activity can block IL-8 mRNA expression induced by UfCP in NHBE cells. These results demonstrate that UfCP-induced expression of IL-8 involves a transcriptional mechanism and activation of p38 MAPK in NHBE cells.
Inhaled NO improves early pulmonary function and modifies lung growth and elastin deposition in a baboon model of neonatal chronic lung disease
Authors: McCurnin Donald C. , Pierce Richard A. , Chang Ling Yi , Gibson Linda L. , Osborne-Lawrence Sherri , Yoder Bradley A. , Kerecman Jay D. , Albertine Kurt H. , Winter Vicki T. , Coalson Jacqueline J. , Crapo James D. , Grubb Peter H. , Shaul Philip W.
Published: February 2005

Nitric oxide (NO) serves multiple functions in the developing lung, and pulmonary NO production is decreased in a baboon model of chronic lung disease (CLD) after premature birth at 125 days (d) gestation (term = 185d). To determine whether postnatal NO administration alters the genesis of CLD, the effects of inhaled NO (iNO, 5 ppm) were assessed in the baboon model over 14d. iNO caused a decrease in pulmonary artery pressure in the first 2d and a greater rate of spontaneous closure of the ductus arteriosus, and lung compliance was greater and expiratory resistance was improved during the first week. With iNO, postmortem pressure-volume curves were shifted upward, lung DNA content and cell proliferation were increased, and lung growth was preserved to equal that which occurs during the same period in utero. In addition, the excessive elastin deposition characteristic of CLD was normalized by iNO, and there was evidence of stimulation of secondary crest development. Thus, in the baboon model of CLD, iNO improves early pulmonary function and alters lung growth and extracellular matrix deposition. As such, NO biosynthetic pathway dysfunction may contribute to the pathogenesis of CLD.
Neuropeptide Y prepares rats for scheduled feeding
Authors: Drazen Deborah L. , Wortman Matthew D. , Seeley Randy J. , Woods Stephen C.
Published: February 2005

When neuropeptide Y (NPY) is administered centrally, meal-anticipatory responses are elicited. If an increase of endogenous NPY is a signal that heralds an imminent large caloric load, timed daily NPY injections may be expected to condition meal-anticipatory responses that facilitate ingestion. Rats received 4-h access to food beginning in the morning and then timed (1600 h), daily third-ventricular injections of NPY or saline for 7 days. On test day ( day 8), animals received the conditioning drug (NPY or saline) or the opposite drug. Food was available immediately after injection on test day, and intake was measured. Rats conditioned with NPY and then given saline ate significantly more than rats conditioned with saline and then given saline; they ate the same amount as rats given NPY. Although they ate more, rats trained with NPY did not have changed plasma glucose, insulin, or ghrelin. These data suggest that NPY plays a role in mediating conditionable food-anticipatory responses that help to cope with the effects of large caloric loads.
Blood flow response to muscle contractions is more closely related to metabolic rate than contractile work
Authors: Hamann Jason J. , Kluess Heidi A. , Buckwalter John B. , Clifford Philip S.
Published: February 2005

The magnitude of the blood flow response to exercise has been linked to both the contractile work performed and the metabolic cost of the activity. Under certain conditions, contractile work and metabolic cost may be dissociated. This study examined the blood flow response to trains of contractions when contraction duration was manipulated under conditions of similar tension-time indexes (isometric analog of work). Previous investigations have shown that trains of short-duration contractions have a greater ATP utilization, which may result from an augmented ion transport required for muscle activation and relaxation. On the basis of these findings, we hypothesized that the blood flow response would be greater to a train of short-duration contractions than a train of long-duration contractions. Canine gastrocnemius-plantaris muscle ( n = 8) was isolated, and blood flow assessed with an ultrasound flow probe placed around the popliteal artery. The sciatic nerve was stimulated to produce two contraction protocols that resulted in similar contraction-to-rest ratios: short duration: 0.25 s/0.75 s vs. long duration: 1 s /3 s. In accord with the design of the experiment, the tension-time indexes were identical for the two contraction protocols (short: 18.6 ± 1.0 vs. long: 18.6 ± 1.0 kN·s). Steady-state oxygen consumption was greater in the short-duration contractions (17.2 ± 0.9 ml·100 g−1·min−1) than in the long-duration contractions (11.7 ± 0.7 ml·100 g−1·min−1). Similarly, the steady-state blood flow was greater in contractions of short duration (125 ± 7 ml/min) compared with long-duration contractions (92 ± 7 ml/min). Contractions of short duration resulted in significantly higher oxygen consumptions and blood flows compared with contractions of long duration despite the same total contractile work. The blood flow response to muscle contraction appears to be more closely associated with muscle metabolism than contractile work performed.
Practice reduces motor unit discharge variability in a hand muscle and improves manual dexterity in old adults
Authors: Kornatz Kurt W. , Christou Evangelos A. , Enoka Roger M.
Published: February 2005

A steadiness-improving intervention was used to determine the contribution of variability in motor unit discharge rate to the fluctuations in index finger acceleration and manual dexterity in older adults. Ten healthy and sedentary old adults (age 72.9 ± 5.8 yr; 5 men) participated in the study involving abduction of the left index finger. Single motor unit activity was recorded in the first dorsal interosseus muscle before, after 2 wk of light-load training (10% maximal load), and after 4 wk of heavy-load training (70% maximal load). As expected, the light-load training was effective in reducing the fluctuations in index finger acceleration during slow shortening (0.25 ± 0.12 to 0.13 ± 0.08 m/s2) and lengthening contractions (0.29 ± 0.10 to 0.14 ± 0.06 m/s2). Along with the decline in the magnitude of the fluctuations, there was a parallel decrease in the coefficient of variation for discharge rate during both contraction types (33.8 ± 6.8 to 25.0 ± 5.9%). The heavy-load training did not further improve either the fluctuations in acceleration or discharge rate variability. Furthermore, the manual dexterity of the left hand improved significantly with training (Purdue pegboard test: 11 ± 3 to 14 ± 1 pegs). Bivariate correlations indicated that the reduction in fluctuations in motor output during shortening ( r2 = 0.24) and lengthening ( r2 = 0.14) contractions and improvement in manual dexterity ( r2 = 0.26) was directly associated with a decline in motor unit discharge rate variability. There was a strong association between the fluctuations in motor output and manual dexterity ( r2 = 0.56). These results indicate that practice of a simple finger task was accompanied by a reduction in the discharge rate variability of motor units, a decrease in the fluctuations in motor output of a hand muscle, and an improvement in the manual dexterity of older adults.
Serum Levels of Type II Secretory Phospholipase A2 and the Risk of Future Coronary Artery Disease in Apparently Healthy Men and Women
Authors: Boekholdt S. Matthijs , Keller Tymen T. , Wareham Nicholas J. , Luben Robert , Bingham Sheila A. , Day Nicholas E. , Sandhu Manjinder S. , Jukema J. Wouter , Kastelein John J.P. , Hack C. Erik , Khaw Kay-Tee
Published: February 2005

Objectives—

To study the prospective relationship between serum levels of type II secretory phospholipase A2 (sPLA2) and the risk of future coronary artery disease (CAD) in apparently healthy men and women.

Methods and Results—

We conducted a prospective nested case-control study among apparently healthy men and women aged 45 to 79 years. Cases (n=1105) were people in whom fatal or nonfatal CAD developed during follow-up. Controls (n=2209) were matched by age, sex, and enrollment time. sPLA2 levels were significantly higher in cases than controls (9.5 ng/mL; interquartile range [IQR], 6.4 to 14.8 versus 8.3 ng/mL; IQR, 5.8 to 12.6;
P
<0.0001). sPLA2 plasma levels significantly correlated with age, body mass index, systolic blood pressure, high-density lipoprotein (HDL) cholesterol levels, and C-reactive protein (CRP) levels. Taking into account matching for sex and age and adjusting for body mass index, smoking, diabetes, systolic blood pressure, low-density lipoprotein cholesterol, HDL cholesterol, and CRP levels, the risk of future CAD was 1.34 (1.02 to 1.71;
P
=0.02) for people in the highest sPLA2 quartile, compared with those in the lowest (
P
for linearity=0.03).

Conclusion—

Elevated levels of sPLA2 were associated with an increased risk of future CAD in apparently healthy individuals. The magnitude of the association was similar to that observed between CRP and CAD risk, and both associations were independent.
C-Reactive Protein and Annexin A5 Bind to Distinct Sites of Negatively Charged Phospholipids Present in Oxidized Low-Density Lipoprotein
Authors: van Tits Lambertus , de Graaf Jacqueline , Toenhake Helga , van Heerde Waander , Stalenhoef Anton
Published: February 2005

Objective—

To investigate binding of C-reactive protein (CRP) and annexin A5, 2 proteins with high affinity for negatively charged phospholipids, to oxidized low-density lipoprotein (LDL) and the consequences of these interactions for subsequent binding of oxidized LDL to monocyte/macrophage-like U937 cells.

Methods and Results—

We found that CRP and annexin A5 at physiological concentrations bind Ca
++
dependently to oxidized phosphatidylcholine present in oxidized LDL but not to native LDL. Binding of CRP to oxidized LDL did not interfere with binding of annexin A5, and vice versa. In the presence of 2 to 10 mg/L CRP, binding of
125
I-labeled oxidized LDL to undifferentiated U937 cells increased 50% to 100%. This effect was independent of the presence of complement and could be inhibited by irrelevant IgG and by antibodies to CD64 but not by annexin A5. Annexin A5 alone had no effect on binding of oxidized LDL to the cells.

Conclusions—

These findings suggest that: (1) CRP and annexin A5 at physiological concentrations bind to distinct sites of negatively charged phospholipids present in oxidized LDL; (2) CRP enhances binding of oxidized LDL to monocytic/macrophage-like cells via Fcγ receptors; and (3) annexin A5 does not antagonize the CRP-induced enhanced binding of oxidized LDL to U937 cells.
Antiangiogenic Activity of a Domain Deletion Mutant of Tissue Plasminogen Activator Containing Kringle 2
Authors: Carroll Veronica A. , Nikitenko Leonid L. , Bicknell Roy , Harris Adrian L.
Published: February 2005

Objective—

The thrombolytic therapy drug, Reteplase, is a domain deletion mutant of tissue plasminogen activator (tPA), comprising the kringle 2 and protease (K2P) domains. Some kringle domains of hemostatic proteins are antiangiogenic and promote apoptosis. The objective of this study was to investigate whether K2P is an angiogenesis inhibitor because of the presence of kringle 2.

Methods and Results—

K2P inhibited basic fibroblast growth factor-induced human endothelial cell proliferation and migration. Inhibition was not dependent on the protease activity of K2P because similar results were obtained with catalytically inactivated K2P. Purification of the kringle 2 domain derived from elastase cleavage of K2P at the Arg
275
–Ile
276
bond revealed that inhibition was mediated by this domain. In addition, K2P inhibited angiogenesis in vivo and increased endothelial cell apoptosis.

Conclusions—

Wound healing and angiogenesis are severely compromised by K2P. These data provide new mechanistic insights into the bleeding complications observed in some patients while undergoing thrombolytic therapy with this drug. In addition, we identify the kringle 2 domain of tPA as a novel target for antiangiogenic therapy.
S-Adenosylmethionine and 5-Methyltetrahydrofolate Are Associated With Endothelial Function After Controlling for Confounding by Homocysteine
Authors: Spijkerman A.M.W. , Smulders Y.M. , Kostense P.J. , Henry R.M.A. , Becker A. , Teerlink T. , Jakobs C. , Dekker J.M. , Nijpels G. , Heine R.J. , Bouter L.M. , Stehouwer C.D.A.
Published: February 2005

Objective—

To explore to what extent homocysteine, S-adenosylmethionine (SAM), S-adenosylhomocysteine, total folate, 5-methyltetrahydrofolate (5-MTHF), vitamin B12, and vitamin B6 are associated with endothelium-dependent, flow-mediated vasodilation (FMD), and whether these associations are stronger in individuals with diabetes or other cardiovascular risk factors.

Methods and Results—

In this population-based study of 608 elderly people, FMD and endothelium-independent nitroglycerin-mediated dilation (NMD) were ultrasonically estimated from the brachial artery (absolute change in diameter [μm]). High SAM and low 5-MTHF were significantly associated with high and low FMD, respectively (linear regression coefficient, [95% confidence interval]): 48.57 μm (21.16; 75.98) and −32.15 μm (−59.09; −5.20), but high homocysteine was not (−15.11 μm (−42.99; 12.78). High SAM and low 5-MTHF were also significantly associated with high and low NMD, respectively. NMD explained the association of 5-MTHF with FMD but not of SAM. No interactions were observed for diabetes or cardiovascular risk factors.

Conclusions—

In this elderly population, both SAM and 5-MTHF are associated with endothelial and smooth muscle cell function. The effect of homocysteine on endothelial function is relatively small compared with SAM and 5-MTHF. The relative impact of SAM, 5-MTHF, and homocysteine, and the mechanisms through which these moieties may affect endothelial and smooth muscle cell function need clarification.
Serum Antibody Levels to
Actinobacillus actinomycetemcomitans
Predict the Risk for Coronary Heart Disease
Authors: Pussinen Pirkko J. , Nyyssönen Kristiina , Alfthan Georg , Salonen Riitta , Laukkanen Jari A. , Salonen Jukka T.
Published: February 2005

Objective—

The association between serum antibody levels to major periodontal pathogens and coronary heart disease (CHD) was analyzed in a prospective population-based study.

Methods and Results—

The population comprised 1023 men (aged 46 to 64 years) in the Kuopio Ischemic Heart Disease Study. The subjects with CHD at baseline (n=113) were more often seropositive for
Porphyromonas gingivalis
IgA (38.9% versus 28.5%,
P
=0.021) and IgG (60.2% versus 46.7%,
P
=0.007) than those without CHD. During the 10-year follow-up, 109 men free from CHD at baseline experienced an acute myocardial infarction or CHD death. The men with an end point were more often seropositive for
Actinobacillus actinomycetemcomitans
IgA (15.5% versus 10.2%,
P
=0.019) than those who remained healthy. In the highest tertile of
A. actinomycetemcomitans
IgA-antibodies compared with the lowest one, the relative risk (RR) for an end point adjusted for CHD risk factors was 2.0 (95% confidence interval [CI], 1.2 to 3.3). In the
Porphyromonas gingivalis
IgA-antibody tertiles, the highest RR of 2.1 (1.3 to 3.4) was observed in the second tertile. All antibody levels correlated positively with the carotid artery intima-media thickness.

Conclusions—

High-serum antibody levels to major periodontal pathogens are associated with subclinical, prevalent, and future incidence of CHD. Periodontal pathogens or host response against them may contribute to the pathogenesis of CHD.
Insulin Signaling in Arteries Prevents Smooth Muscle Apoptosis
Authors: Nakazawa T. , Chiba T. , Kaneko E. , Yui K. , Yoshida M. , Shimokado K.
Published: February 2005

Objective—Insulin is an antiapoptotic factor of cultured vascular cells, but it is not clear whether it also exerts antiapoptotic effects on vascular cells in vivo. We studied insulin receptor signaling in the arteries of normal and diabetic rats to establish whether insulin exhibits antiapoptotic activity toward vascular smooth muscle cells in vivo as well as in vitro.

Methods and Results—Western blot analysis and real-time polymerase chain reaction revealed α- and β-subunits of the insulin receptor in association with insulin receptor substrate-1 and phosphatidylinositol 3-kinase in the media of the aorta and carotid artery. The insulin receptor signaling pathway was partially activated under physiological conditions, further activated by intravenous insulin injection, and was attenuated in streptozotocin-induced diabetic rats. Lipopolysaccharide injection induced more apoptosis of vascular smooth muscle cells in diabetic rats than in control rats, whereas insulin prevented apoptosis in the aortic wall. An in vitro study suggested that the antiapoptotic effect of insulin was mediated by phosphatidylinositol 3-kinase.

Conclusions—Insulin is an antiapoptotic factor of vascular smooth muscle cells in vitro and in vivo. Decreased insulin activity on the artery may increase smooth muscle cell death and cause unstable plaque formation associated with diabetes.
Lymphocytes Are Not Required for the Rapid Onset of Coronary Heart Disease in Scavenger Receptor Class B Type I/Apolipoprotein E Double Knockout Mice
Authors: Karackattu Sharon L. , Picard Michael H. , Krieger Monty
Published: February 2005

Objective—Scavenger receptor class B type I (SR-BI)/apolipoprotein E (apoE) double knockout (dKO) mice exhibit many features of human coronary heart disease (CHD), including occlusive coronary atherosclerosis, cardiac hypertrophy, myocardial infarctions, and premature death. Here we determined the influence of B and T lymphocytes, which can contribute to atherosclerosis, ischemia–reperfusion injury, and cardiomyocyte death, on pathology in dKO mice.

Method and Results—The lymphocyte-deficient SR-BI/apoE/recombination activating gene 2 (RAG2) triple knockout mice and corresponding dKO controls generated for this study exhibited essentially identical lipid-rich coronary occlusions, myocardial infarctions, cardiac dysfunction, and premature death (average lifespans 41.6±0.6 and 42.0±0.5 days, respectively).

Conclusions—B and T lymphocytes and associated immunoglobulin-mediated inflammation are not essential for the development and progression of CHD in dKO mice. Strikingly, the dKO mice bred for this study (mixed C57BL/6×SV129×BALB/c background; strain 2) compared with the previously described dKO mice (75:25 C57BL/6:SV129 background; strain 1) had a shorter mean lifespan and steeper survival curve, characteristics especially attractive for studying the effects of environmental, pharmacological, and genetic manipulations on cardiac pathophysiology.
Serum Amyloid A and Lipoprotein Retention in Murine Models of Atherosclerosis
Authors: O’Brien Kevin D. , McDonald Thomas O. , Kunjathoor Vidya , Eng KimLi , Knopp Eleanor A. , Lewis Katherine , Lopez Roland , Kirk Elizabeth A. , Chait Alan , Wight Thomas N. , deBeer Frederick C. , LeBoeuf Renee C.
Published: February 2005

Objective—

Elevated serum amyloid A (SAA) levels are associated with increased cardiovascular risk in humans. Because SAA associates primarily with lipoproteins in plasma and has proteoglycan binding domains, we postulated that SAA might mediate lipoprotein retention on atherosclerotic extracellular matrix.

Methods and Results—

Immunohistochemistry was performed for SAA, apolipoprotein A-I (apoA-I), apolipoprotein B (apoB), and perlecan on proximal aortic lesions from chow-fed low-density lipoprotein receptor (LDLR)
−/−
and apoE
−/−
mice euthanized at 10, 50, and 70 weeks. SAA was detected on atherosclerotic lesion extracellular matrix at all time points in both strains. SAA area correlated highly with lesion areas (apoE
−/−
,
r
=0.76; LDLR
−/−
,
r
=0.86), apoA-I areas (apoE
−/−
,
r
=0.88; LDLR
−/−
,
r
=0.80), apoB areas (apoE
−/−
,
r
=0.74; LDLR
−/−
,
r
=0.89), and perlecan areas (apoE
−/−
,
r
=0.83; LDLR
−/−
,
r
=0.79) (all
P
<0.0001). In vitro, SAA enrichment increased high-density lipoprotein (HDL) binding to heparan sulfate proteoglycans, and immunoprecipitation experiments using plasma from apoE
−/−
and LDLR
−/−
mice demonstrated that SAA was present on both apoA-I–containing and apoB-containing lipoproteins.

Conclusions—

In chow-fed apoE
−/−
and LDLR
−/−
mice, SAA is deposited in murine atherosclerosis at all stages of lesion development, and SAA immunoreactive area correlates highly with lesion area, apoA-I area, apoB area, and perlecan area. These findings are consistent with a possible role for SAA-mediated lipoprotein retention in atherosclerosis.
Emergence of a R-Type Ca
2+
Channel (Ca
V
2.3) Contributes to Cerebral Artery Constriction After Subarachnoid Hemorrhage
Authors: Ishiguro Masanori , Wellman Theresa L. , Honda Akira , Russell Sheila R. , Tranmer Bruce I. , Wellman George C.
Published: February 2005

Cerebral aneurysm rupture and subarachnoid hemorrhage (SAH) inflict disability and death on thousands of individuals each year. In addition to vasospasm in large diameter arteries, enhanced constriction of resistance arteries within the cerebral vasculature may contribute to decreased cerebral blood flow and the development of delayed neurological deficits after SAH. In this study, we provide novel evidence that SAH leads to enhanced Ca
2+
entry in myocytes of small diameter cerebral arteries through the emergence of R-type voltage-dependent Ca
2+
channels (VDCCs) encoded by the gene Ca
V
2.3. Using in vitro diameter measurements and patch clamp electrophysiology, we have found that L-type VDCC antagonists abolish cerebral artery constriction and block VDCC currents in cerebral artery myocytes from healthy animals. However, 5 days after the intracisternal injection of blood into rabbits to mimic SAH, cerebral artery constriction and VDCC currents were enhanced and partially resistant to L-type VDCC blockers. Further, SNX-482, a blocker of R-type Ca
2+
channels, reduced constriction and membrane currents in cerebral arteries from SAH animals, but was without effect on cerebral arteries of healthy animals. Consistent with our biophysical and functional data, cerebral arteries from healthy animals were found to express only L-type VDCCs (Ca
V
1.2), whereas after SAH, cerebral arteries were found to express both Ca
V
1.2 and Ca
V
2.3. We propose that R-type VDCCs may contribute to enhanced cerebral artery constriction after SAH and may represent a novel therapeutic target in the treatment of neurological deficits after SAH.
Insulin-Like Growth Factor-I Regulates Proliferation and Osteoblastic Differentiation of Calcifying Vascular Cells via Extracellular Signal-Regulated Protein Kinase And Phosphatidylinositol 3-Kinase Pathways
Authors: Radcliff Kristen , Tang Tri-Bang , Lim Jina , Zhang Zina , Abedin Moeen , Demer Linda L. , Tintut Yin
Published: February 2005

Vascular calcification develops within atherosclerotic lesions and results from a process similar to osteogenesis. One of the paracrine regulators of bone-derived osteoblasts, insulin-like growth factor-I (IGF-I), is also present in atherosclerotic lesions. To evaluate its possible role in vascular calcification, we assessed its in vitro effects on proliferation and differentiation in calcifying vascular cells (CVCs), a subpopulation of bovine aortic medial cells. Results showed that IGF-I inhibited spontaneous CVC differentiation and mineralization as evidenced by decreased alkaline phosphatase (AP) activity and decreased matrix calcium incorporation, respectively. Furthermore, IGF-I inhibited the AP activity induced by bacterial lipopolysaccharide, TNF-α, or H
2
O
2
. It also induced CVC proliferation based on
3
H-thymidine incorporation. Results from Northern analysis and tests using IGF-I analogs suggest that IGF-I effects are mediated through the IGF-I receptor. IGF-I also activated both the extracellular signal-regulated protein kinase (ERK) and phosphatidylinositol 3-kinase (PI3K) pathways. Inhibition of either the ERK or PI3K pathway reversed IGF-I effects on CVC proliferation and AP activity, suggesting a common downstream target. Overexpression of ERK activator also mimicked IGF-I inhibition of lipopolysaccharide-induced AP activity. These results suggest that IGF-I promotes proliferation and inhibits osteoblastic differentiation and mineralization of vascular cells via both ERK and PI3K pathways.
Rescue of Monocrotaline-Induced Pulmonary Arterial Hypertension Using Bone Marrow–Derived Endothelial-Like Progenitor Cells
Authors: Zhao Yidan D. , Courtman David W. , Deng Yupu , Kugathasan Lakshmi , Zhang Qiuwang , Stewart Duncan J.
Published: February 2005

Pulmonary arterial hypertension (PAH) is characterized by a progressive increase in pulmonary vascular resistance caused by narrowing and loss of pulmonary microvasculature, which in its late stages becomes refractory to traditional therapies. We hypothesized that bone marrow–derived endothelial progenitor cells (EPCs), which normally function to repair and regenerate blood vessels, would restore pulmonary hemodynamics and increase microvascular perfusion in the rat monocrotaline (MCT) model of PAH. Mononuclear cells were isolated from the bone marrow of syngeneic Fisher-344 rats by Ficoll gradient centrifugation and cultured for 7 to 10 days in endothelial growth medium. Fluorescently labeled endothelial-like progenitor cells (ELPCs) engrafted at the level of the distal pulmonary arterioles and incorporated into the endothelial lining in the MCT-injured lung. The administration of ELPCs 3 days after MCT nearly completely prevented the increase in right ventricular systolic pressure seen at 3 weeks with MCT alone (31.5±0.95 versus 48±3 mm Hg, respectively;
P
<0.001), whereas injection of skin fibroblasts had no protective effect (50.9±5.4 mm Hg). Delayed administration of progenitor cells 3 weeks after MCT prevented the further progression of PAH 2 weeks later (ie, 5 weeks after MCT), whereas only animals receiving ELPCs transduced with human endothelial NO-synthase (eNOS) exhibited significant reversal of established disease at day 35 (31±2 mm Hg,
P
<0.005) compared with day 21 (50±3 mm Hg). Fluorescent microangiography revealed widespread occlusion of pulmonary precapillary arterioles 3 weeks after MCT, whereas arteriolar-capillary continuity and microvascular architecture was preserved with the administration of syngeneic ELPCs. Moreover, the delivery of ELPCs to rats with established PAH resulted in marked improvement in survival, which was greatest in the group receiving eNOS-transduced cells. We conclude that bone marrow–derived ELPCs can engraft and repair the MCT-damaged lung, restoring microvasculature structure and function. Therefore, the regeneration of lung vascular endothelium by injection of progenitor cells may represent a novel treatment paradigm for patients with PAH.
Angiopoietin-1 Promotes Cardiac and Skeletal Myocyte Survival Through Integrins
Authors: Dallabrida Susan M. , Ismail Nesreen , Oberle Julianne R. , Himes Blanca E. , Rupnick Maria A.
Published: February 2005

Cardiac myocyte loss, regardless of insult, can trigger compensatory myocardial remodeling leading to heart failure. Identifying mediators of cardiac myocyte survival may advance clinical efforts toward myocardial preservation. Angiopoietin-1 limits ischemia-induced cardiac injury. This benefit is ascribed to angiogenesis because the receptor, tie2, is largely endothelial-specific. We propose that direct, non-tie2 interactions of angiopoietin-1 on cardiac myocytes contribute to this cardioprotection. We found that mouse C2C12 skeletal myocytes lack tie2, yet dose-dependently adhered to angiopoietin-1 and angiopoietin-2 similarly to laminin, fibronectin, vitronectin, and more than to collagen-I, -III, and -IV. Adhesion was divalent cation-mediated (Mn
2+
, Ca
2+
, not Mg
2+
), blocked with EDTA/EGTA, RGD-based peptides, and select integrin subunit antibodies. Similar findings were obtained with human skeletal myocytes (HSMs) and freshly isolated rat neonatal cardiac myocytes (NCMs). Furthermore, angiopoietin-1 conferred significant survival advantage exceeding that of most cell matrices, which was not fully explained by differences in cell adhesion. Angiopoietin-1 promoted survival of serum-starved C2C12, HSM, and NCM (MTT, trypan blue) and prevented taxol-induced apoptosis (caspase-3). Immobilized and soluble angiopoietin-1 phosphorylated Akt
S473
and MAPK
p42/44
, (not FAK
Y397
) in C2C12 more than in endothelial cells and more than did angiopoietin-2 or cell matrices. EDTA, RGD-based peptides, and some integrin antibodies blocked these responses. Angiopoietin-1 activated HSM and NCM Akt
S473
and MAPK
p42/44
survival pathways. We propose that this novel function contributes to developmental and cardioprotective actions of angiopoietin-1 presently attributed to vascular effects alone. Angiopoietin-1 may prove therapeutically valuable in cardiac remodeling by supporting myocyte viability and preserving pump function. The full text of this article is available online at http://circres.ahajournals.org.
Prevalence of Stroke Among Chinese, Malay, and Indian Singaporeans
Authors: Venketasubramanian Narayanaswamy , Tan Louis C.S. , Sahadevan Suresh , Chin Jing J. , Krishnamoorthy Ennapadam S. , Hong Ching Y. , Saw Seang M.
Published: February 2005

Background and Purpose—

Stroke prevalence data among mixed Asian populations are lacking. Prevalence rates of stroke were studied among Singaporeans aged ≥50 years of Chinese, Malay, and Indian origin.

Methods—

Study participants were selected by disproportionate stratified random sampling by race. Trained interviewers performed face-to-face interviews with subjects using the World Health Organization screening protocol for neurological diseases. Data were also collected on a self-report of stroke. Subjects suspected to have had a stroke underwent a clinical evaluation to diagnose or exclude stroke. Case notes review was performed for those who were unable to come for clinical evaluation.

Results—

The study involved 14 906 participants: 6734 men, 8172 women, age range 52 to 106 years, Chinese:Malay:Indian ratio 3:1:1. Participation rate was 66.9%. Six hundred and six were diagnosed to have a stroke, yielding a crude prevalence rate of 4.05% (95% CI, 3.75 to 4.38) and a World Health Organization world population age-gender-standardized rate of 3.65% (95% CI, 3.36 to 3.96). Prevalence rates rose with age (
P
<0.001 for trend) and were higher among men compared with women, 4.53% (95% CI, 4.05 to 5.07) versus 2.91% (95% CI, 2.57 to 3.29),
P
<0.01. Age and gender-standardized rates among Chinese, Malays, and Indians were 3.76% (95% CI, 3.38 to 4.17), 3.32 (95% CI, 2.72 to 4.07), and 3.62% (95% CI, 2.95 to 4.44), respectively,
P
>0.2. Prevalence was highest among Chinese men at 4.78% (95% CI, 4.14 to 5.50) and lowest among Malay women at 2.81% (95% CI, 2.08 to 3.81),
P
=0.01.

Conclusions—

There is no difference in stroke prevalence among Chinese, Malay, and Indian Singaporeans. Prevalence is highest among Chinese men and lowest among Malay women. The reasons for these differences warrant further investigation.
Tuftsin Fragment 1–3 Is Beneficial When Delivered After the Induction of Intracerebral Hemorrhage
Authors: Wang Jian , Tsirka Stella E.
Published: February 2005

Background and Purpose—

Microglial activation may contribute to the pathogenesis of the brain injury in intracerebral hemorrhage (ICH). We have reported that the tripeptide macrophage/microglial inhibitory factor (MIF), Thr-Lys-Pro, inhibits microglial activation and results in functional improvement when given before the onset of hemorrhage. In this study, we investigate the protection and efficacy of treatment when MIF is administered 2 hours after collagenase injection.

Methods—

ICH was induced by injecting bacterial collagenase into the caudate nucleus; 100 μL MIF (500 μmol/L) was delivered via a micro-osmotic pump. Infusion of MIF or saline (control) was initiated 2 hours after collagenase injection and continued for 24 or 72 hours. Microglial activation and macrophage infiltration were assessed by 5-
d
-4 and F4/80 immunofluorescence, respectively. Production of reactive oxygen species was visualized by in situ detection of ethidium. Degenerating neurons were assessed by Fluoro-Jade B staining. Neurological deficits, brain injury volumes, and brain edema were assessed at 24 and 72 hours after MIF/saline treatment.

Results—

MIF can inhibit microglial activation and macrophage infiltration, attenuate the numbers of ethidium-positive cells compared with the saline-treated control mice, reduce the injury volume, edema, and degenerating neurons, and improve the neurological functional outcome.

Conclusions—

Activated microglia/macrophages are important contributors to brain injury after ICH. MIF could be a valuable neuroprotective agent for the treatment of ICH, if treatment is initiated soon after the onset of hemorrhage.
Reduction of Cerebral Infarction in Stroke-Prone Spontaneously Hypertensive Rats by Statins Associated With Amelioration of Oxidative Stress
Authors: Nagotani Shoko , Hayashi Takeshi , Sato Keiko , Zhang Wenri , Deguchi Kentaro , Nagano Isao , Shoji Mikio , Abe Koji
Published: February 2005

Background and Purpose—

This study aimed to clarify the effect of statins on spontaneous stroke and to examine the antioxidative effect in artificial transient middle cerebral artery occlusion (tMCAO).

Methods—

Stroke-prone spontaneous hypertensive rats (SHR-SP) were treated with pitavastatin, atorvastatin, simvastatin, or vehicle for 4 weeks. Physiological parameters, serum lipids, and infarct volumes were examined. The markers for oxidative stresses on lipids and DNA were immunohistochemically detected in vehicle-treated or simvastatin-treated SHR-SP with tMCAO.

Results—

Atorvastatin and simvastatin decreased infarct volumes, with simvastatin most effective. Simvastatin significantly reduced immunoreactivities for oxidative stress markers for lipids and DNA in neurons after tMCAO.

Conclusions—

The results suggest that the antioxidative properties of statins may be implicated in their beneficial effects against neuronal damage in cerebral ischemia.