bluuebunny/crossref_metadata_2025 huggingface dataset:
Competency-Based General Physics Instruction with a One-Man Staff
Authors: Aubel J. L.
Published: September 2005

A competency-based instruction (CBI) system is one in which a student must regularly demonstrate satisfactory understanding or performance of specified competencies in order to proceed to new material. A CBI system for teaching general physics with a one man staff is outlined. Mastery and timing results are reported which suggest that for many students CBI produces more efficient learning and better student attitudes.
The Chemistry-Physics Program at the University of Wisconsin-Green Bay
Authors: Rhyner C. R. , Norman J. C. , Fischbach F. A.
Published: September 2005

The integrated chemistry-physics program at the University of Wisconsin-Green Bay is described. The structure of the University and of the academic programs are major factors in the success of the program. Observations on the relative advantages and disadvantages of this integrated approach are considered.
Child Development and the Physical Environment
Authors: Evans Gary W.
Published: September 2005

Characteristics of the physical environment that influence child development are discussed. Topics include behavioral toxicology, noise, crowding, housing and neighborhood quality, natural settings, schools, and day care settings. Socioemotional, cognitive, motivation, and psychophysiological outcomes in children and youths are reviewed. Necessary methodological and conceptual advances are introduced as well.
Atherogenic region and diet diminish glycocalyx dimension and increase intima-to-media ratios at murine carotid artery bifurcation
Authors: van den Berg Bernard M. , Spaan Jos A. E. , Rolf Titia M. , Vink Hans
Published: September 2005

It was hypothesized that endothelial glycocalyx perturbation contributes to increased vulnerability of the arterial wall exposed to atherogenic risk factors. Glycocalyx and intima-to-media ratios (IMR) were studied at a low- and a high-risk region within the murine carotid artery (common region) and internal carotid branch (sinus region) in control C57BL/6J (C57BL6) and age-matched C57BL/6J/apoE*3-Leiden (apoE*3; on an atherogenic diet) mice. Electron micrographs revealed significantly thinner glycocalyces [73 (SD 36) vs. 399 (SD 174) nm, P < 0.05] and greater IMR [0.096 (SD 0.045) vs. 0.044 (SD 0.023), P < 0.05] at the sinus region of C57BL6 mice than in the common region. Thinner glycocalyces [100 (SD 27) vs. 399 (SD 174) nm, P < 0.05] and greater IMR [0.071 (SD 0.024) vs. 0.044 (SD 0.023), P < 0.05] were also observed in the common region of age-matched apoE*3 mice on an atherogenic diet for 6 wk vs. C57BL6 mice on a normal diet. Greater IMR were due to greater intima layers, without significant changes in media layer dimension. In addition, atherogenic diet resulted in increased endothelial cell thickness at the sinus region [0.85 (SD 0.49) vs. 0.53 (SD 0.28) μm, P < 0.05] but not at the common region [0.66 (SD 0.37) vs. 0.62 (SD 0.32) μm]. It is concluded that both regional and diet-induced increases in atherogenic risk are associated with smaller glycocalyx dimensions and greater IMR and that vascular sites with diminished glycocalyx are more vulnerable to proinflammatory and atherosclerotic sequelae.
Chronic activation of PPARα is detrimental to cardiac recovery after ischemia
Authors: Sambandam Nandakumar , Morabito Dominique , Wagg Cory , Finck Brian N. , Kelly Daniel P. , Lopaschuk Gary D.
Published: September 2005

High fatty acid oxidation (FAO) rates contribute to ischemia-reperfusion injury of the myocardium. Because peroxisome proliferator-activated receptor (PPAR)α regulates transcription of several FAO enzymes in the heart, we examined the response of mice with cardiac-restricted overexpression of PPARα (MHC-PPARα) or whole body PPARα deletion including the heart (PPARα−/−) to myocardial ischemia-reperfusion injury. Isolated working hearts from MHC-PPARα and nontransgenic (NTG) littermates were subjected to no-flow global ischemia followed by reperfusion. MHC-PPARα hearts had significantly higher FAO rates during aerobic and postischemic reperfusion (aerobic 1,479 ± 171 vs. 699 ± 117, reperfusion 1,062 ± 214 vs. 601 ± 70 nmol·g dry wt−1·min−1; P < 0.05) and significantly lower glucose oxidation rates compared with NTG hearts (aerobic 225 ± 36 vs. 1,563 ± 165, reperfusion 402 ± 54 vs. 1,758 ± 165 nmol·g dry wt−1·min−1; P < 0.05). In hearts from PPARα−/−mice, FAO was significantly lower during aerobic and reperfusion (aerobic 235 ± 36 vs. 442 ± 75, reperfusion 205 ± 25 vs. 346 ± 38 nmol·g dry wt−1·min−1; P < 0.05) whereas glucose oxidation was significantly higher compared with wild-type (WT) hearts (aerobic 2,491 ± 631 vs. 901 ± 119, reperfusion 2,690 ± 562 vs. 1,315 ± 172 nmol·g dry wt−1·min−1; P < 0.05). Increased FAO rates in MHC-PPARα hearts were associated with a markedly lower recovery of cardiac power (45 ± 9% vs. 71 ± 6% of preischemic levels in NTG hearts; P < 0.05). In contrast, the percent recovery of cardiac power of PPARα−/−hearts was not significantly different from that of WT hearts (80 ± 8% vs. 75 ± 9%). This study demonstrates that chronic activation of PPARα is detrimental to the cardiac recovery during reperfusion after ischemia.
Electrical connections between left superior pulmonary vein, left atrium, and ligament of Marshall: implications for mechanisms of atrial fibrillation
Authors: Tan Alex Y. , Chou Chung-Chuan , Zhou Shengmei , Nihei Motoki , Hwang Chun , Peter C. Thomas , Fishbein Michael C. , Chen Peng-Sheng
Published: September 2005

The importance of the ligament of Marshall (LOM) to rapid activations within the left superior pulmonary vein (LSPV) during atrial fibrillation (AF) remains poorly understood. We aimed to characterize the importance of electrical coupling between the LSPV with the left atrium (LA) and the LOM in the generation of high-frequency activations within this PV. We performed high-density mapping of the LSPV-LA-LOM junction in eight dogs, using 1,344 electrodes with a 1-mm resolution before and after posterior ostial ablation to diminish PV-LA electrical connections. A LOM potential was recordable up to 6.5 mm (SD 2.2) into the LSPV in all dogs during sinus rhythm (SR) and LA pacing. Functional LOM-LSPV electrical connections bypassing the PV-LA junction were present in five of eight dogs. Direct LOM-LSPV connections contributed to 46.5% (SD 16.0) of LSPV activations during AF, resulting in a greater propensity to develop focal activations ( P < 0.05) and a higher activation rate during AF of LSPVs with direct LOM connections compared with those without ( P < 0.03). Posterior LSPV ostial ablation without damaging the anterior wall or LOM slowed residual LA-PV conduction ( P < 0.001). This diminished PV-LA coupling prevented the reinduction of LSPV focal activations in all dogs. However, persistent LOM focal activations in two dogs continued to activate the LSPV rapidly [cycle length 151.8 ms (SD 4.8)] via direct LOM-LSPV connections. LOM-LSPV connection forms an accessory pathway that contributes to the electrical coupling between LSPV and LA during SR and AF. This pathway may contribute to rapid activations within the LSPV during AF.
Effect of paced breathing on ventilatory and cardiovascular variability parameters during short-term investigations of autonomic function
Authors: Pinna G. D. , Maestri R. , La Rovere M. T. , Gobbi E. , Fanfulla F.
Published: September 2005

Paced breathing (PB) around 0.25 Hz has been advocated as a means to avoid confounding and to standardize measurements in short-term investigations of autonomic cardiovascular regulation. Controversy remains, however, as to whether it causes any alteration in autonomic control. We addressed this issue in 40 supine, middle-aged, healthy volunteers by assessing the changes induced by PB (0.25 Hz for 8 min) on 1) ventilatory parameters, 2) the indexes of autonomic control of cardiovascular function, and 3) the spectral indexes of cardiovascular variability. Subjects were grouped into group 1 ( n = 31), if spontaneous breathing was regular and within the high-frequency (HF) band (0.15–0.45 Hz), or group 2 ( n = 9), if it was irregular or slow (<0.15 Hz). In both groups, PB was accompanied by an increase in minute ventilation (both groups, P < 0.01), whereas tidal volume increased only in group 1 ( P = 0.0003). End-tidal CO2 decreased by [median (lower quartile, upper quartile)] −0.2 (−0.5, −0.1)% ( group 1, P < 0.0001) and −0.6 (−0.8, −0.5)% ( group 2, P = 0.008). Mean R-R interval and systolic and diastolic pressure remained remarkably stable (all P ≥ 0.13, both groups). No significant changes were observed in spectral indexes of R-R and pressure variability (all P ≥ 0.12, measured only in group 1 to avoid confounding), except in the HF power of pressure signals, which significantly increased (all P < 0.05) in association with increased tidal volume. In conclusion, PB at 0.25 Hz causes a slight hyperventilation and does not affect traditional indexes of autonomic control or, in subjects with spontaneous breathing in the HF band, most relevant spectral indexes of cardiovascular variability. These findings support the notion that PB does not alter cardiovascular autonomic regulation compared with spontaneous breathing.
Desferoxamine and ethyl-3,4-dihydroxybenzoate protect myocardium by activating NOS and generating mitochondrial ROS
Authors: Philipp Sebastian , Cui Lin , Ludolph Barbara , Kelm Malte , Schulz Rainer , Cohen Michael V. , Downey James M.
Published: September 2005

Protection from a prolyl hydroxylase domain-containing enzyme (PHD) inhibitor, desferoxamine (DFO), was recently reported to be dependent on production of reactive oxygen species (ROS). Ischemic preconditioning triggers the protected state by stimulating nitric oxide (NO) production to open mitochondrial ATP-sensitive K+(mitoKATP) channels, generating ROS required for protection. We tested whether DFO and a second PHD inhibitor, ethyl-3,4-dihydroxybenzoate (EDHB), might have similar mechanisms. EDHB and DFO increased ROS generation by 50–75% ( P < 0.001) in isolated rabbit cardiomyocytes. This increase after EDHB exposure was blocked by Nω-nitro-l-arginine methyl ester (l-NAME), an NO synthase (NOS) inhibitor; ODQ, a guanylyl cyclase antagonist; and Rp-8-bromoguanosine-3′,5′-cyclic monophosphorothioate Rp isomer, a PKG blocker, thus implicating the NO pathway in EDHB's signaling. Glibenclamide, a nonselective KATPchannel blocker, or 5-hydroxydecanoate, a selective mitoKATPchannel antagonist, also prevented EDHB's ROS production, as did blockade of mitochondrial electron transport with myxothiazol. NOS is activated by Akt. However, neither wortmannin, an inhibitor of phosphatidylinositol-3-kinase, nor Akt inhibitor blocked EDHB-induced ROS generation, indicating that EDHB initiates signaling downstream of Akt. DFO also increased ROS production, and this effect was blocked by ODQ, 5-hydroxydecanoate, and N-(2-mercaptopropionyl)glycine, an ROS scavenger. DFO increased cardiomyocyte production of nitrite, a metabolite of NO, and this effect was blocked by an inhibitor of NOS. DFO also spared ischemic myocardium in intact hearts. This infarct-sparing effect was blocked by ODQ, l-NAME, and N-(2-mercaptopropionyl)glycine. Hence, DFO and EDHB stimulate NO-dependent activation of PKG to open mitoKATPchannels and produce ROS, which act as second messengers to trigger entrance into the preconditioned state.
Nuclear localization of protein kinase C-α induces thyroid hormone receptor-α1 expression in the cardiomyocyte
Authors: Kenessey Agnes , Sullivan Elizabeth Ann , Ojamaa Kaie
Published: September 2005

Maladaptive cardiac hypertrophy results in phenotypic changes in several genes that are thyroid hormone responsive, suggesting that thyroid hormone receptor (TR) function may be altered by cellular kinases, including protein kinase C (PKC) isozymes that are activated in pathological hypertrophy. To investigate the role of PKC signaling in regulating TR function, cultured neonatal rat ventricular myocytes were transduced with adenovirus (Ad) expressing wild-type (wt) or kinase-inactive (dn) PKCα or constitutively active (ca) PKCδ and PKCε. Overexpression of wtPKCα, but not caPKCδ or caPKCε, induced a 28-fold increase ( P < 0.001) in TRα1 protein in the nuclear compartment and a smaller increase in the cytosol. Furthermore, TRα1 mRNA was increased 55-fold ( P < 0.001). This effect of PKCα was dependent on its kinase activity because dnPKCα was without effect. Phorbol 12-myristate 13-acetate (PMA) induced nuclear translocation of endogenous PKCα and Ad-wtPKCα concomitantly with an increase in nuclear TRα1 protein. In contrast, PMA-induced nuclear translocation of dnPKCα resulted in a decrease of TRα1. The increase in TRα1 protein in Ad-wtPKCα-transduced cardiomyocytes was not the result of a reduced rate of protein degradation, nor was the half-life of TRα1 mRNA prolonged, suggesting a PKCα-mediated effect on TRα transcription. Although phosphorylation of ERK1/2 was increased in Ad-wtPKCα-transduced cells, inhibition of phospho-ERK did not change TRα1 expression. PKCα overexpression in cardiomyocytes caused marked repression of triiodothyronine (T3)-responsive genes, α-myosin heavy chain, and the sarcoplasmic reticulum calcium-activated adenosinetriphosphatase SERCA2. Treatment with T3for 4 h resulted in significant reductions of PKCα in nuclear and cytosolic compartments, and decreased TRα1 mRNA and protein, with normalization of phenotype. These results implicate PKCα as a regulator of TR function and suggest that nuclear localization of PKCα may control transcription of the TRα gene, and consequently, affect cardiac phenotype.
Involvement of Na+/Ca2+ exchanger in catecholamine-induced increase in intracellular calcium in cardiomyocytes
Authors: Saini Harjot K. , Tripathi Onkar N. , Zhang Shetuan , Elimban Vijayan , Dhalla Naranjan S.
Published: September 2005

Although sarcolemmal (SL) Na+/Ca2+ exchanger is known to regulate the intracellular Ca2+ concentration ([Ca2+]i), its involvement in catecholamine-induced increase in [Ca2+]i is not fully understood. To gain some information in this regard, isolated rat cardiomyocytes were treated with different agents, which are known to modify Ca2+ movements, in the absence or presence of a β-adrenoceptor agonist, isoproterenol, and [Ca2+]i in cardiomyocytes was determined spectrofluorometrically with fura-2 AM. Treatment with isoproterenol did not alter [Ca2+]i in quiescent cardiomyocytes, whereas the ATP (purinergic receptor agonist)-induced increase in [Ca2+]i was significantly potentiated by isoproterenol. Unlike ryanodine and cyclopiazonic acid, which affect the sarcoplasmic reticulum function, SL L-type Ca2+ channel blockers verapamil and diltiazem, as well as a SL Ca2+-pump inhibitor, vanadate, caused a significant depression in the isoproterenol-induced increase in [Ca2+]i. The SL Na+/Ca2+ exchange blockers amiloride, Ni2+, and KB-R7943 also attenuated the isoproterenol-mediated increase in [Ca2+]i. Combination of KB-R7943 and verapamil showed additive inhibitory effects on the isoproterenol-induced increase in [Ca2+]i. The isoproterenol-induced increase in [Ca2+]i in KCl-depolarized cardiomyocytes was augmented by low Na+; this augmentation was significantly depressed by treatment with KB-R7943. The positive inotropic action of isoproterenol in isolated hearts was also reduced by KB-R7943. These data suggest that in addition to SL L-type Ca2+ channels, SL Na+/Ca2+ exchanger seems to play an important role in catecholamine-induced increase in [Ca2+]i in cardiomyocytes.
PPAR-γ inhibits ANG II-induced cell growth via SHIP2 and 4E-BP1
Authors: Benkirane Karim , Amiri Farhad , Diep Quy N. , El Mabrouk Mohammed , Schiffrin Ernesto L.
Published: September 2005

The present study evaluated the effects of peroxisome proliferator-activated receptor (PPAR)-γ activators on ANG II-induced signaling pathways and cell growth. Vascular smooth muscle cells (VSMC) derived from rat mesenteric arteries were treated with ANG II, with/without the AT1 receptor blocker valsartan or the AT2 receptor blocker PD-123319, after pretreatment for 24 h with the PPAR-γ activators 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) or rosiglitazone. Both 15d-PGJ2 and rosiglitazone decreased ANG II-induced DNA synthesis. Rosiglitazone treatment increased nuclear PPAR-γ expression and activity in VSMC. However, rosiglitazone did not alter expression of PPAR-α/β, ERK 1/2, Akt, or ANG II receptors. 15d-PGJ2 and rosiglitazone decreased ERK 1/2 and Akt peak activity, both of which were induced by ANG II via the AT1 receptor. Rosiglitazone inhibited ANG II-enhanced phosphorylation of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), as well as Src homology (SH) 2-containing inositol phosphatase 2 (SHIP2). PPAR-γ activation reduced ANG II-induced growth associated with inhibition of ERK 1/2, Akt, 4E-BP1, and SHIP2. Modulation of these pathways by PPAR-γ activators may contribute to regression of vascular remodeling in hypertension.
Ischemia-reperfusion-induced calpain activation and SERCA2a degradation are attenuated by exercise training and calpain inhibition
Authors: French Joel P. , Quindry John C. , Falk Darin J. , Staib Jessica L. , Lee Youngil , Wang Kevin K. W. , Powers Scott K.
Published: September 2005

The Ca2+-activated protease calpain has been shown to play a deleterious role in the heart during ischemia-reperfusion (I/R). We tested the hypothesis that exercise training would minimize I/R-induced calpain activation and provide cardioprotection against I/R-induced injury. Hearts from adult male rats were isolated in a working heart preparation, and myocardial injury was induced with 25 min of global ischemia followed by 45 min of reperfusion. In sedentary control rats, I/R significantly increased calpain activity and impaired cardiac performance (cardiac work during reperfusion = 24% of baseline). Compared with sedentary animals, exercise training prevented the I/R-induced rise in calpain activity and improved cardiac work (recovery = 80% of baseline). Similar to exercise, pharmacological inhibition of calpain activity resulted in comparable cardioprotection against I/R injury (recovery = 86% of baseline). The exercise-induced protection against I/R-induced calpain activation was not due to altered myocardial protein levels of calpain or calpastatin. However, exercise training was associated with increased myocardial antioxidant enzyme activity (Mn-SOD, catalase) and a reduction in oxidative stress. Importantly, exercise training also prevented the I/R-induced degradation of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2a. These findings suggest that increases in endogenous antioxidants may diminish the free radical-mediated damage and/or degradation of Ca2+ handling proteins (such as SERCA2a) typically observed after I/R. In conclusion, these results support the concept that calpain activation is an important component of I/R-induced injury and that exercise training provides cardioprotection against I/R injury, at least in part, by attenuating I/R-induced calpain activation.
Postnatal intermittent hypoxia alters baroreflex function in adult rats
Authors: Soukhova-O'Hare Galia K. , Cheng Zixi (Jack) , Roberts Andrew M. , Gozal David
Published: September 2005

Chronic perinatal intermittent hypoxia (IH) could have long-term cardiovascular effects by altering baroreflex function. To examine this hypothesis, we exposed rats ( n = 6/group) for postnatal days 1–30 or prenatal embryonic days 5–21 to IH (8% ambient O2 for 90 s after 90 s of 21% of O2, 12 h/day) or to normoxia (control). Baroreflex sensitivity (BRS) and cardiac chronotropic responses were examined in anesthetized animals 3.5–5 mo later by infusing phenylephrine or sodium nitroprusside (6–12 μg/min iv, 1–2 min) during normoxia and after 18 min of acute IH (IHA). In controls after IHA, baroreflex gain was 42% ( P < 0.05) less than during normoxia. BRS in the postnatal IH group during normoxia was ∼50% less than in control rats and similar to controls after IHA. The heart rate response to phenylephrine in the IH group was also less than in controls ( P < 0.05) and was not changed by IHA. BRS and heart rate responses in the prenatal IH group were similar to the normoxic control group. Vagal efferent projections to atrial ganglia neurons in rats after postnatal IH ( n = 4) were examined by injecting tracer into the left nucleus ambiguus. After 35 days of postnatal IH, basket ending density was reduced by 17% ( P < 0.001) and vagal axon varicose contacts by 56% ( P < 0.001) compared with controls. We conclude that reduction of vagal efferent projections in cardiac ganglia could be a cause of long-term modifications in baroreflex function.
Venular endothelium-derived NO can affect paired arteriole: a computational model
Authors: Kavdia Mahendra , Popel Aleksander S.
Published: September 2005

Venular endothelial cells can release nitric oxide (NO) in response to intraluminal flow both in isolated venules and in vivo. Experimental studies suggest that venular endothelium-released NO causes dilation of the adjacent paired arteriole. In the vascular wall, NO stimulates its target hemoprotein, soluble guanylate cyclase (sGC), which relaxes smooth muscle cells. In this study, a computational model of NO transport for an arteriole and venule pair was developed to determine the importance of the venular endothelium-released NO and its transport to the adjacent arteriole in the tissue. The model predicts that the tissue NO levels are affected within a wide range of parameters, including NO-red blood cell reaction rate and NO production rate in the arteriole and venule. The results predict that changes in the venular NO production affected not only venular endothelial and smooth muscle NO concentration but also endothelial and smooth muscle NO concentration in the adjacent arteriole. This suggests that the anatomy of microvascular tissue can permit the transport of NO from arteriolar to venular side, and vice versa, and may provide a mechanism for dilation of proximal arterioles by venules. These results will have significant implications for our understanding of tissue NO levels in both physiological and pathophysiological conditions.
fMLP-stimulated release of reactive oxygen species from adherent leukocytes increases microvessel permeability
Authors: Zhu Longkun , He Pingnian
Published: September 2005

Our previous study ( Am J Physiol Heart Circ Physiol 288: H1331–H1338, 2005) demonstrated that TNF-α induced significant leukocyte adhesion without causing increases in microvessel permeability, and that formyl-Met-Leu-Phe-OH (fMLP)-stimulated neutrophils in the absence of adhesion increased microvessel permeability via released reactive oxygen species (ROS). The objective of our present study is to investigate the mechanisms that regulate neutrophil respiratory burst and the roles of fMLP-stimulated ROS release from adherent leukocytes in microvessel permeability. A technique that combines single-microvessel perfusion with autologous blood perfusion was employed in venular microvessels of rat mesenteries. Leukocyte adhesion was induced by systemic application of TNF-α. Microvessel permeability was assessed by measuring hydraulic conductivity ( Lp). The 2-h autologous blood perfusion after TNF-α application increased leukocyte adhesion from 1.2 ± 0.2 to 13.3 ± 1.6 per 100 μm of vessel length without causing increases in Lp. When fMLP (10 μM) was applied to either perfusate ( n = 5) or superfusate ( n = 8) in the presence of adherent leukocytes, Lptransiently increased to 4.9 ± 0.9 and 4.4 ± 0.3 times the control value, respectively. Application of superoxide dismutase or an iron chelator, deferoxamine mesylate, after fMLP application prevented or attenuated the Lpincrease. Chemiluminescence measurements in isolated neutrophils demonstrated that TNF-α alone did not induce ROS release but that preexposure of neutrophils to TNF-α in vivo or in vitro potentiated fMLP-stimulated ROS release. These results suggest a priming role of TNF-α in fMLP-stimulated neutrophil respiratory burst and indicate that the released ROS play a key role in leukocyte-mediated permeability increases during acute inflammation.
Flutamide restores cardiac function after trauma-hemorrhage via an estrogen-dependent pathway through upregulation of PGC-1
Authors: Hsieh Ya-Ching , Yang Shaolong , Choudhry Mashkoor A. , Yu Huang-Ping , Bland Kirby I. , Schwacha Martin G. , Chaudry Irshad H.
Published: September 2005

Although previous studies have shown that flutamide improves cardiovascular function after trauma-hemorrhage, the mechanisms responsible for the salutary effect remain unknown. We hypothesized that flutamide mediates its beneficial effects via an estrogen-dependent pathway through upregulation of peroxisome proliferator-activated receptor-γ coactivator 1 (PGC-1). PGC-1, a key regulator of cardiac mitochondrial ATP production, induces mitochondrial DNA (mtDNA)-encoded genes such as cytochrome- c oxidase (COX) subunit I, II, and III (COX I, COX II, and COX III), which regulates mitochondrial oxidative phosphorylation. To test this hypothesis, male rats underwent trauma-hemorrhage (mean arterial pressure of 35–40 mmHg for ∼90 min) followed by resuscitation. At the onset of resuscitation, rats received vehicle, flutamide (25 mg/kg body wt), flutamide in combination with estrogen receptor (ER) antagonist ICI-182,780 (3 mg/kg body wt), or ICI-182,780 alone. Flutamide administration after trauma-hemorrhage restored the depressed cardiac function and increased cardiac testosterone, estrogen levels, and aromatase activity. These increases were accompanied by normalized cardiac ER-α and ER-β protein levels, PGC-1, and COX I mRNA expression, mitochondrial COX activity, and ATP contents. However, cardiac dihydrotestosterone, 5α-reductase II, androgen receptor protein levels, and mtDNA-encoded genes COX II and COX III were unaffected by flutamide treatment. The flutamide-mediated restoration of cardiac function, the increases in aromatase activity and estrogen levels, ER-α, ER-β, PGC-1, COX I, COX activity, and ATP contents were, however, abolished when ER antagonist ICI-182,780 was administrated along with flutamide. These findings suggest that the salutary effect of flutamide on cardiac function after trauma-hemorrhage is mediated via an estrogen-dependent pathway through upregulation of PGC-1.
Myocardial subproteomic analysis of a constitutively active Rac1-expressing transgenic mouse with lethal myocardial hypertrophy
Authors: Buscemi Nina , Murray Chris , Doherty-Kirby Amanda , Lajoie Gilles , Sussman Mark A. , Van Eyk Jennifer E.
Published: September 2005

A two-dimensional gel electrophoresis (2-DE)-based proteomic approach was used to study a transgenic mouse model of acerbated dilated cardiomyopathy in which the small monomeric GTPase, Rac1, was constitutively expressed exclusively in the myocardium. A subfractionation procedure allowed for the focused analysis of both cytoplasmic and myofilament protein-enriched extracts of ventricular tissue from Rac1 transgenic and age-matched nontransgenic (NTG) mice. The majority of these mice displayed severe hypertrophy (heart-to-body weight ratios >2-fold greater in the Rac1 mice) and died from overt heart failure between days 14 and 17. Comparative 2-DE analysis (pH 3–10, 12% SDS-PAGE) derived from Rac1 ( n = 4) and NTG ( n = 4) groups revealed differences in mean protein spot intensities. Twelve proteins from the cytoplasmic protein-enriched extract met our criteria for robustness and spot resolution and were identified. These proteins represent a broad distribution of cellular functions with only some previously implicated in myocardial hypertrophy. The myofilament subproteome displayed no change in posttranslational modification, but further analysis by one-dimensional Western blot showed increased quantities of myofilament proteins in the Rac1 mouse ventricles. Additionally, three proteins with different functionality that were altered in the cytoplasmic protein-enriched subproteome, tubulin β-chain, manganese superoxide dismutase, and malate dehydrogenase, were analyzed at days 7, 9, and 11 to assess their role in the development of the dilated cardiomyopathic phenotype. The quantity of all three proteins peaked at day 9, suggesting an early response in cardiac hypertrophic failure.
Role of alveolar macrophage and migrating neutrophils in hemorrhage-induced priming for ALI subsequent to septic challenge
Authors: Lomas-Neira Joanne , Chung Chun-Shiang , Perl Mario , Gregory Stephen , Biffl Walter , Ayala Alfred
Published: September 2005

Acute lung injury (ALI) is identified with the targeting/sequestration of polymorphonuclear leukocytes (PMN) to the lung. Instrumental to PMN targeting are chemokines [e.g., macrophage inflammatory protein-2 (MIP-2), keratinocyte-derived chemokine (KC), etc.] produced by macrophage, PMN, and other resident pulmonary cells. However, the relative contribution of resident pulmonary macrophages as opposed to PMN in inducing ALI is poorly understood. We therefore hypothesize that depletion of peripheral blood PMN and/or the oblation of a macrophage-mediated PMN chemokine signal (via macrophage deficiency) will reduce the inflammation and ALI observed in mice following hemorrhage (Hem) and subsequent sepsis (CLP) in our murine model of ALI. To examine this we pretreated mice with either 500 μg anti-mouse Gr1 antibody/animal (to deplete PMN) or subjected mice deficient in mature macrophage (B6C3Fe-a/a-CsF1op) to Hem (90 min at 35 ± 5 mmHg) followed by resuscitation. Twenty-four hours post-Hem, mice were subjected to CLP and killed 24 h later, and lung tissue samples were collected. Our data showed that in the absence of either peripheral blood PMN or mature tissue macrophages there was a suppression of IL-6, KC, and MIP-2 levels in lung tissue from Hem/CLP mice as well as a reduction in PMN influx to the lung and lung injury (bronchoalveolar lavage fluid protein). In contrast, lung tissue IL-10 and TNF-α levels were suppressed in the macrophage-deficient Hem/CLP mice compared with PMN-depleted Hem/CLP mice. Together, these data suggest that both the PMN and the macrophage are required to induce inflammation seen here, however, macrophage not PMN regulate the release of IL-10, independent of local changes in TNF.
Gene transfer with inducible nitric oxide synthase decreases production of urea by arginase in pulmonary arterial endothelial cells
Authors: Stanley Kate P. , Chicoine Louis G. , Young Tamara L. , Reber Kristina M. , Lyons C. Richard , Liu Yusen , Nelin Leif D.
Published: September 2005

Nitric oxide (NO) is a vasodilator produced from l-arginine (l-Arg) by NO synthase (NOS). Gene therapy for hypertensive disorders has been proposed using the inducible isoform of NOS (iNOS). l-Arg also can be metabolized to urea and l-ornithine (l-Orn) by arginase, and l-Orn can be metabolized to proline and/or polyamines, which are vital for cellular proliferation. To determine the effect of iNOS gene transfer on arginase, we transfected bovine pulmonary arterial endothelial cells (bPAEC) with an adenoviral vector containing the gene for iNOS (AdiNOS). As expected, NO production in AdiNOS bPAEC was substantially greater than in control bPAEC. Although urea production was significantly less in the AdiNOS bPAEC than in the control bPAEC, despite similar levels of arginase I protein, AdiNOS transfection of bPAEC had no effect on the uptake of l-Arg. Inhibiting NO production with Nω-nitro-l-arginine methyl ester increased urea production, and inhibiting urea production with l-valine increased nitrite production, in AdiNOS bPAEC. The addition of l-Arg to the medium increased urea production by AdiNOS bPAEC in a concentration-dependent manner. Thus, in these iNOS-transfected bPAEC, the transfected iNOS and native arginase compete for a common intracellular pool of l-Arg. This competition for substrate resulted in impaired proliferation in the AdiNOS-transfected bPAEC. These findings suggest that the use of iNOS gene therapy for pulmonary hypertensive disorders may not only be beneficial through NO-mediated pulmonary vasodilation but also may decrease vascular remodeling by limiting l-Orn production by native arginase.
Cyclic nucleotide regulation of store-operated Ca2+influx in airway smooth muscle
Authors: Ay Binnaz , Iyanoye Adeyemi , Sieck Gary C. , Prakash Y. S. , Pabelick Christina M.
Published: September 2005

Sarcoplasmic reticulum (SR) Ca2+release and plasma membrane Ca2+influx are key to intracellular Ca2+([Ca2+]i) regulation in airway smooth muscle (ASM). SR Ca2+depletion triggers influx via store-operated Ca2+channels (SOCC) for SR replenishment. Several clinically relevant bronchodilators mediate their effect via cyclic nucleotides (cAMP, cGMP). We examined the effect of cyclic nucleotides on SOCC-mediated Ca2+influx in enzymatically dissociated porcine ASM cells. SR Ca2+was depleted by 1 μM cyclopiazonic acid in 0 extracellular Ca2+([Ca2+]o), nifedipine, and KCl (preventing Ca2+influx through L-type and SOCC channels). SOCC was then activated by reintroduction of [Ca2+]oand characterized by several techniques. We examined cAMP effects on SOCC by activating SOCC in the presence of 1 μM isoproterenol or 100 μM dibutryl cAMP (cell-permeant cAMP analog), whereas we examined cGMP effects using 1 μM (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO nitric oxide donor) or 100 μM 8-bromoguanosine 3',5'-cyclic monophosphate (cell-permeant cGMP analog). The role of protein kinases A and G was examined by preexposure to 100 nM KT-5720 and 500 nM KT-5823, respectively. SOCC-mediated Ca2+influx was dependent on the extent of SR Ca2+depletion, sensitive to Ni2+and La3+, but not inhibitors of voltage-gated influx channels. cAMP as well as cGMP potently inhibited Ca2+influx, predominantly via their respective protein kinases. Additionally, cAMP cross-activation of protein kinase G contributed to SOCC inhibition. These data demonstrate that a Ni2+/La3+-sensitive Ca2+influx in ASM triggered by SR Ca2+depletion is inhibited by cAMP and cGMP via a protein kinase mechanism. Such inhibition may play a role in the bronchodilatory response of ASM to clinically relevant drugs (e.g., β-agonists vs. nitric oxide).
Tryptase activates phosphatidylinositol 3-kinases proteolytically independently from proteinase-activated receptor-2 in cultured dog airway smooth muscle cells
Authors: Brown James K. , Hollenberg Morley D. , Jones Cary A.
Published: September 2005

Mast cell tryptase is a potent mitogen for many cells in the airways and lung, but the cellular mechanisms for its growth stimulatory effects are poorly understood. Our major goal was to determine whether tryptase activates phosphatidylinositol 3-kinases (PI 3-kinases) in cultured dog tracheal smooth muscle cells to induce its mitogenic effects. After exposure to tryptase, cells were lysed. Immunocomplexes prepared from the lysates using an antibody to the p85 subunit of PI 3-kinase, but not using anti-phosphotyrosine antibodies, possessed increased capacity to phosphorylate inositol on its D3 hydroxyl group. Tryptase also increased phosphorylation of Akt, a downstream target of PI 3-kinases. This effect was abolished by one PI 3-kinase inhibitor, wortmannin, and attenuated by another, LY-294004, which also blocked tryptase's mitogenic effects. Treatment of tryptase with p-amidino phenylmethanesulfonyl fluoride, to abolish its proteolytic activity irreversibly, inhibited its stimulatory effects on Akt phosphorylation. Proteinase-activated receptor-2 (PAR-2)-activating peptides failed to increase Akt phosphorylation in cultured dog tracheal smooth muscle cells, but the PAR-2-activating peptides did induce brisk increases in Akt phosphorylation in Madin-Darby canine kidney cells. We concluded that tryptase activates PI 3-kinases in cultured dog tracheal smooth muscle cells to induce its potent mitogenic effects. These effects of tryptase on PI 3-kinases appear to occur via novel proteolytic mechanisms independent from PAR-2. Also, tryptase, although comparable in mitogenic potency to platelet-derived growth factor (PDGF), induces considerably less tyrosine phosphorylation on proteins than occur in response to PDGF.
Culture of murine nasal epithelia: model for cystic fibrosis
Authors: Grubb B. R. , Rogers T. D. , Diggs P. C. , Boucher R. C. , Ostrowski L. E.
Published: September 2005

The ion transport defects reported for human cystic fibrosis (CF) airways are reproduced in nasal epithelia of the CF mouse. Although this tissue has been studied in vivo using the nasal potential difference technique and as a native tissue mounted in the Ussing chamber, little information is available on cultured murine nasal epithelia. We have developed a polarized cell culture model of primary murine nasal epithelia in which the CF tissue exhibits not only a defect in cAMP-mediated Cl−secretion but also the Na+hyperabsorption and upregulation of the Ca2+-activated Cl−conductance observed in human airways. Both the wild-type and CF cultures were constituted predominantly of undifferentiated cuboidal columnar cells, with most cultures exhibiting a small number of ciliated cells. Although no goblet cells were observed, RT-PCR demonstrated the expression of Muc5ac RNA after ∼22 days in culture. The CF tissue exhibited an adherent layer of mucus similar to the mucus plaques reported in the distal airways of human CF patients. Furthermore, we found that treatment of CF preparations with a Na+channel blocker for 7 days prevented formation of mucus adherent to epithelial surfaces. The cultured murine nasal epithelial preparation should be an excellent model tissue for gene transfer studies and pharmacological studies of Na+channel blockers and mucolytic agents as well as for further characterization of CF ion transport defects. Culture of nasal epithelia from ΔF508 mice will be particularly useful in testing drugs that allow ΔF508 CFTR to traffic to the membrane.
Mechanisms of endothelin-1-induced contraction in pulmonary arteries from chronically hypoxic rats
Authors: Weigand Letitia , Sylvester J. T. , Shimoda Larissa A.
Published: September 2005

Endothelin-1 (ET-1), a potent vasoconstrictor, is believed to contribute to the pathogenesis of hypoxic pulmonary hypertension. Previously we demonstrated that contraction induced by ET-1 in intrapulmonary arteries (IPA) from chronically hypoxic (CH) rats occurred independently of changes in intracellular Ca2+concentration ([Ca2+]i), suggesting that ET-1 increased Ca2+sensitivity. The mechanisms underlying this effect are unclear but could involve the activation of myosin light chain kinase, Rho kinase, PKC, or tyrosine kinases (TKs), including those from the Src family. In this study, we examined the effect of pharmacological inhibitors of these kinases on maximum tension generated by IPA from CH rats (10% O2for 21 days) in response to ET-1. Experiments were conducted in the presence of nifedipine, an L-type Ca2+channel blocker, to isolate the component of contraction that occurred without a change in [Ca2+]i. The mean change in tension caused by ET-1 (10−8M) expressed as a percent of the maximum response to KCl was 184.0 ± 39.0%. This response was markedly inhibited by the Rho kinase inhibitors Y-27632 and HA-1077 and the TK inhibitors genistein, tyrphostin A23, and PP2. In contrast, staurosporine and GF-109203X, inhibitors of PKC, had no significant inhibitory effect on the tension generated in response to ET-1. We conclude that the component of ET-1-induced contraction that occurs without a change in [Ca2+]iin IPA from CH rats requires activation of Rho kinase and TKs, but not PKC.
Advanced glycation end products and the kidney
Authors: Bohlender Jürgen M. , Franke Sybille , Stein Günter , Wolf Gunter
Published: September 2005

Advanced glycation end products (AGEs) are a heterogeneous group of protein and lipids to which sugar residues are covalently bound. AGE formation is increased in situations with hyperglycemia (e.g., diabetes mellitus) and is also stimulated by oxidative stress, for example in uremia. It appears that activation of the renin-angiotensin system may contribute to AGE formation through various mechanisms. Although AGEs could nonspecifically bind to basement membranes and modify their properties, they also induce specific cellular responses including the release of profibrogenic and proinflammatory cytokines by interacting with the receptor for AGE (RAGE). However, additional receptors could bind AGEs, adding to the complexity of this system. The kidney is both: culprit and target of AGEs. A decrease in renal function increases circulating AGE concentrations by reduced clearance as well as increased formation. On the other hand, AGEs are involved in the structural changes of progressive nephropathies such as glomerulosclerosis, interstitial fibrosis, and tubular atrophy. These effects are most prominent in diabetic nephropathy, but they also contribute to renal pathophysiology in other nondiabetic renal diseases. Interference with AGE formation has therapeutic potential for preventing the progression of chronic renal diseases, as shown from data of animal experiments and, more recently, the first clinical trials.
Flow-mediated dilation does/does not reflect nitric oxide-mediated endothelial function
Authors: Austin Clare E.
Published: September 2005

This letter is in response to the Point:Counterpoint series “Flow-mediated dilation does/does not reflect nitric oxide-mediated endothelial function” that appeared in the September issue (vol. 99: 1233–1238, 2005; doi:10.1152/japplphysiol.00601.2005; http://jap.physiology.org/content/vol99/issue3/2005 ).
Augmented Mechanical Response of Muscle Thin-Fiber Sensory Receptors Recorded from Rat Muscle–Nerve Preparations In Vitro After Eccentric Contraction
Authors: Taguchi Toru , Sato Jun , Mizumura Kazue
Published: September 2005

Unaccustomed strenuous exercise, especially that from eccentric muscular work, often causes muscle tenderness, which is a kind of mechanical hyperalgesia. We developed an animal model of delayed-onset muscle soreness (DOMS) from eccentric muscular contraction (ECC) in rats and demonstrated the existence of muscle tenderness by means of behavioral pain tests and c-Fos protein expression in the spinal dorsal horn. The purpose of the present study was to examine whether the sensitivities of muscle thin-fiber sensory receptors to mechanical, chemical, and thermal stimuli were altered after repetitive ECC in a rat model of DOMS. ECC was caused in the animals by electrical stimulation of the common peroneal nerve innervating the extensor digitorum longus muscle (EDL) while the muscle was being stretched. Activities of single thin-fiber receptors (sensitive to pressure but insensitive to stretch, with conduction velocity slower than 2.0 m/s) were recorded from muscle (EDL)–nerve preparations in vitro 2 days after ECC when mechanical hyperalgesia was at its peak. The mechanical threshold of thin-fiber receptors was found to be very much lower in the ECC preparations than in the nontreated control (CTR) [median 65.4 mN (interquartile range [IQR]; 46.6–122.0 mN) in the CTR preparation vs. 38.2 mN (IQR; 26.8–55.8 mN) in the ECC, P < 0.001]. In addition, the total number of evoked discharges during a ramp mechanical stimulus, taken as an index of the magnitude of the mechanical response, nearly doubled in the ECC preparations compared with the CTR [24.7 spikes (IQR; 14.2–37.1 spikes) in the CTR preparation vs. 54.2 spikes (IQR; 24.3–89.0 spikes) in the ECC, P < 0.001]. In contrast, the numbers of discharges induced by chemical (pH 5.5, lactic acid, adenosine triphosphate, and bradykinin) and thermal (cold and heat) stimuli were not different between the two preparations. These results suggest that augmentation of the mechanical response in muscle thin-fiber sensory receptors might be related to the muscle tenderness in DOMS after ECC.
Trial-to-Trial Variability and Its Effect on Time-Varying Dependency Between Two Neurons
Authors: Ventura Valérie , Cai Can , Kass Robert E.
Published: September 2005

The joint peristimulus time histogram (JPSTH) and cross-correlogram provide a visual representation of correlated activity for a pair of neurons, and the way this activity may increase or decrease over time. In a companion paper we showed how a Bootstrap evaluation of the peaks in the smoothed diagonals of the JPSTH may be used to establish the likely validity of apparent time-varying correlation. As noted in earlier studies by Brody and Ben-Shaul et al., trial-to-trial variation can confound correlation and synchrony effects. In this paper we elaborate on that observation, and present a method of estimating the time-dependent trial-to-trial variation in spike trains that may exceed the natural variation displayed by Poisson and non-Poisson point processes. The statistical problem is somewhat subtle because relatively few spikes per trial are available for estimating a firing-rate function that fluctuates over time. The method developed here decomposes the spike-train variability into a stimulus-related component and a trial-specific component, allowing many degrees of freedom to characterize the former while assuming a small number suffices to characterize the latter. The Bootstrap significance test of the companion paper is then modified to accommodate these general excitability effects. This methodology allows an investigator to assess whether excitability effects are constant or time-varying, and whether they are shared by two neurons. In data from two V1 neurons we find that highly statistically significant evidence of dependency disappears after adjustment for time-varying trial-to-trial variation.
A Learning Rule for the Emergence of Stable Dynamics and Timing in Recurrent Networks
Authors: Buonomano Dean V.
Published: September 2005

Neural dynamics within recurrent cortical networks is an important component of neural processing. However, the learning rules that allow networks composed of hundreds or thousands of recurrently connected neurons to develop stable dynamical states are poorly understood. Here I use a neural network model to examine the emergence of stable dynamical states within recurrent networks. I describe a learning rule that can account both for the development of stable dynamics and guide networks to states that have been observed experimentally, specifically, states that instantiate a sparse code for time. Across trials, each neuron fires during a specific time window; by connecting the neurons to a hypothetical set of output units, it is possible to generate arbitrary spatial-temporal output patterns. Intertrial jitter of the spike time of a given neuron increases as a direct function of the delay at which it fires. These results establish a learning rule by which cortical networks can potentially process temporal information in a self-organizing manner, in the absence of specialized timing mechanisms.
Compact compatible topologies for graphs with small cycles
Authors: Neumann-Lara Victor , Wilson Richard G.
Published: September 2005

A topology τ on the vertices of a comparability graph G is
said to be compatible with G if each subgraph H of G
is graph‐connected if and only if it is a connected subspace of
(G, τ). In two previous papers we considered the problem of
finding compatible topologies for a given comparability graph and
we proved that the nonexistence of infinite paths was a necessary
and sufficient condition for the existence of a compact compatible
topology on a tree (that is to say, a connected graph without
cycles) and we asked whether this condition characterized the
existence of a compact compatible topology on a comparability
graph in which all cycles are of length at most n. Here we prove
an extension of the above‐mentioned theorem to graphs whose cycles
are all of length at most five and we show that this is the best
possible result by exhibiting a comparability graph in which all
cycles are of length 6, with no infinite paths, but which has no
compact compatible topology.
Nonextendibility of D(−1)‐triples of the form{1, 10, c}
Authors: Filipin Alan
Published: September 2005

We prove that there do not exist different positive integers
c, d > 1 such that the product of any two distinct elements of the
set {1, 10, c, d}
diminished by 1 is a perfect square.