bluuebunny/crossref_metadata_2025 huggingface dataset:
Cellular Actions of Urethane on Rat Visual Cortical Neurons In Vitro
Authors: Sceniak Michael P. , MacIver M. Bruce
Published: March 2006

Urethane is widely used in neurophysiological experiments to anesthetize animals, yet little is known about its actions at the cellular and synaptic levels. This limits our ability to model systems-level cortical function using results from urethane-anesthetized preparations. The present study found that action potential discharge of cortical neurons in vitro, in response to depolarizing current, was strongly depressed by urethane and this was accompanied by a significant decrease in membrane resistance. Voltage-clamp experiments suggest that the mechanism of this depression involves selective activation of a Ba2+-sensitive K+leak conductance. Urethane did not alter excitatory glutamate-mediated or inhibitory (GABAA- or GABAB-mediated) synaptic transmission. Neither the amplitude nor decay time constant of GABAA- or GABAB-mediated monosynaptic inhibitory postsynaptic currents (IPSCs) were altered by urethane, nor was the frequency of spontaneous IPSCs. These results are consistent with observations seen in vivo during urethane anesthesia where urethane produced minimal disruption of signal transmission in the neocortex.
Microarray Analysis of Bleomycin-Exposed Lymphoblastoid Cells for Identifying Cancer Susceptibility Genes
Authors: Cloos Jacqueline , de Boer Wim P.H. , Snel Mireille H.J. , van den IJssel Paul , Ylstra Bauke , Leemans C. René , Brakenhoff Ruud H. , Braakhuis Boudewijn J.M.
Published: March 2006

The uncovering of genes involved in susceptibility to the sporadic cancer types is a great challenge. It is well established that the way in which an individual deals with DNA damage is related to the chance to develop cancer. Mutagen sensitivity is a phenotype that reflects an individual's susceptibility to the major sporadic cancer types, including colon, lung, and head and neck cancer. A standard test for mutagen sensitivity is measuring the number of chromatid breaks in lymphocytes after exposure to bleomycin. The aim of the present study was to search for the pathways involved in mutagen sensitivity. Lymphoblastoid cell lines of seven individuals with low mutagen sensitivity were compared with seven individuals with a high score. RNA was isolated from cells exposed to bleomycin (4 hours) and from unexposed cells. Microarray analysis (19K) was used to compare gene expression of insensitive and sensitive cells. The profile of most altered genes after bleomycin exposure, analyzed in all 14 cell lines, included relatively many genes involved in biological processes, such as cell growth and/or maintenance, proliferation, and regulation of cell cycle, as well as some genes involved in DNA repair. When comparing the insensitive and sensitive individuals, other differentially expressed genes were found that are involved in signal transduction and cell growth and/or maintenance (e.g., BUB1 and DUSP4). This difference in expression profiles between mutagen-sensitive and mutagen-insensitive individuals justifies further studies aimed at elucidating the genes responsible for the development of sporadic cancers. (Mol Cancer Res 2006;4(2):71–7)
Cardioprotective Mechanisms of Eplerenone on Cardiac Performance and Remodeling in Failing Rat Hearts
Authors: Kobayashi Naohiko , Yoshida Kohtaro , Nakano Shigefumi , Ohno Tomoyuki , Honda Takeaki , Tsubokou Yusuke , Matsuoka Hiroaki
Published: February 2006

Aldosterone may play a pivotal role in the pathophysiology of heart failure. To elucidate the beneficial cardioprotective mechanism of eplerenone, a novel selective aldosterone blocker, we hypothesized that eplerenone stimulates endothelial NO synthase (eNOS) through Akt and inhibits inducible NO synthase (iNOS) via nuclear factor κB (NF-κB) after the development of oxidative stress and activation of the lectin-like, oxidized, low-density lipoprotein receptor 1 (LOX-1) pathway in Dahl salt-sensitive rats with heart failure. Eplerenone (10, 30, and 100 mg/kg per day) was given from the age of the left ventricular hypertrophy stage (11 weeks) to the failing stage (18 weeks) for 7 weeks. The left ventricular end-systolic pressure-volume relationship was evaluated using a conductance catheter. Decreased percentage of fractional shortening by echocardiography and end-systolic pressure-volume relationship in failing rats was significantly ameliorated by eplerenone. Downregulated eNOS expression, eNOS and Akt phosphorylation, and NOS activity in failing rats were increased by eplerenone. Upregulated expression of the mineralocorticoid receptor aldosterone synthase (CYP11B2); NAD(P)H oxidase p22phox, p47phox, gp91phox, iNOS, and LOX-1; and activated p65 NF-κB, protein kinase CβII, c-Src, p44/p42 extracellular signal-regulated kinase, and p70S6 kinase phosphorylation were inhibited by eplerenone. Eplerenone administration resulted in significant improvement of cardiac function and remodeling and upregulation of sarcoplasmic reticulum Ca
2+
-ATPase expression. These findings suggest that eplerenone may have significant therapeutic potential for heart failure, and these cardioprotective mechanisms of eplerenone may be mediated in part by stimulating eNOS through Akt and inhibiting iNOS via NF-κB after activation of the oxidative stress-LOX-1 pathway and signal transduction pathway.
Coexpression of Voltage-Dependent Calcium Channels Cav1.2, 2.1a, and 2.1b in Vascular Myocytes
Authors: Andreasen Ditte , Friis Ulla G. , Uhrenholt Torben R. , Jensen Boye L. , Skøtt Ole , Hansen Pernille B.
Published: February 2006

Voltage-dependent Ca2+channels Cav1.2 (L type) and Cav2.1 (P/Q type) are expressed in vascular smooth muscle cells (VSMCs) and are important for the contraction of renal resistance vessels. In the present study we examined whether native renal VSMCs coexpress L-, P-, and Q-type Ca2+currents. The expression of both Cav2.1a (P-type) and Cav2.1b (Q-type) mRNA was demonstrated by RT-PCR in renal preglomerular vessels from rats and mice. Immunolabeling was performed on A7r5 cells, renal cryosections, and freshly isolated renal VSMCs with anti-Cav1.2 and anti-Cav2.1 antibodies. Conventional and confocal microscopy revealed expression of both channels in all of the smooth muscle cells. Whole-cell patch clamp on single preglomerular VSMCs from mice showed L-, P-, and Q-type currents. Blockade of the L-type currents by calciseptine (20 nmol/L) inhibited 35.6±3.9% of the voltage-dependent Ca2+current, and blocking P-type currents (ω-agatoxin IVA 10 nmol/L) led to 20.2±3.0% inhibition, whereas 300 nmol/L of ω agatoxin IVA (blocking P/Q-type) inhibited 45.0±7.3%. In rat aortic smooth muscle cells (A7r5), blockade of L-type channels resulted in 28.5±6.1% inhibition, simultaneous blockade of L-type and P-type channels inhibited 58.0±11.8%, and simultaneous inhibition of L-, P-, and Q-type channels led to blockade (88.7±5.6%) of the Ca2+current. We conclude that aortic and renal preglomerular smooth muscle cells express L-, P-, and Q-type voltage-dependent Ca2+channels in the rat and mouse.
NADPH Oxidase in the Renal Medulla Causes Oxidative Stress and Contributes to Salt-Sensitive Hypertension in Dahl S Rats
Authors: Taylor Norman E. , Glocka Padden , Liang Mingyu , Cowley Allen W.
Published: February 2006

Dahl salt-sensitive (SS) rats exhibit increased renal medullary oxidative stress and blood pressure salt-sensitivity compared with consomic, salt-resistant SS-13
BN
rats, despite highly similar genetic backgrounds. The present study examined potential sources of renal medullary superoxide in prehypertensive SS rats fed a 0.4% NaCl diet by assessing activity and protein levels of superoxide producing and scavenging enzymes. Superoxide production was nearly doubled in SS rats compared with SS-13
BN
rats as determined by urinary 8-isoprostane excretion and renal medullary oxy-ethidium microdialysate levels. Medullary superoxide production in tissue homogenates was greater in SS rats, and the NADPH oxidase inhibitor diphenylene iodonium preferentially reduced SS levels to those found in SS-13
BN
rats. Dinitrophenol, a mitochondrial uncoupler, eliminated the remaining superoxide production in both strains, whereas inhibition of xanthine oxidase, NO synthase, and cycloxygenase had no effect.
l
-arginine, NO synthase, superoxide dismutase, catalase, and glutathione peroxidase activities between SS and SS-13
BN
rats did not differ. Chronic blood pressure responses to a 4% NaCl diet were then determined in the presence or absence of the NADPH oxidase inhibitor apocynin (3.5 μg/kg per minute), chronically delivered directly into the renal medulla. Apocynin infusion reduced renal medullary interstitial superoxide from 1059±130 to 422±80 (oxyethidium fluorescence units) and mean arterial pressure from 175±4 to 157±6 mm Hg in SS rats, whereas no effects on either were observed in the SS-13
BN
. We conclude that excess renal medullary superoxide production in SS rats contributes to salt-induced hypertension, and NADPH oxidase is the major source of the excess superoxide.
Deletion of Angiotensin-Converting Enzyme 2 Accelerates Pressure Overload-Induced Cardiac Dysfunction by Increasing Local Angiotensin II
Authors: Yamamoto Koichi , Ohishi Mitsuru , Katsuya Tomohiro , Ito Norihisa , Ikushima Masashi , Kaibe Masaharu , Tatara Yuji , Shiota Atsushi , Sugano Sumio , Takeda Satoshi , Rakugi Hiromi , Ogihara Toshio
Published: February 2006

Angiotensin-converting enzyme 2 (ACE2) is a carboxypeptidase that cleaves angiotensin II to angiotensin 1-7. Recently, it was reported that mice lacking ACE2 (

ACE2
−/y

mice) exhibited reduced cardiac contractility. Because mechanical pressure overload activates the cardiac renin-angiotensin system, we used

ACE2
−/y

mice to analyze the role of ACE2 in the response to pressure overload. Twelve-week-old

ACE2
−/y

mice and wild-type (WT) mice received transverse aortic constriction (TAC) or sham operation. Sham-operated

ACE2
−/y

mice exhibited normal cardiac function and had morphologically normal hearts. In response to TAC,

ACE2
−/y

mice developed cardiac hypertrophy and dilatation. Furthermore, their hearts displayed decreased cardiac contractility and increased fetal cardiac gene induction, compared with WT mice. In response to chronic pressure overload,

ACE2
−/y

mice developed pulmonary congestion and increased incidence of cardiac death compared with WT mice. On a biochemical level, cardiac angiotensin II concentration and activity of mitogen-activated protein (MAP) kinases were markedly increased in

ACE2
−/y

mice in response to TAC. Administration of candesartan, an AT
1
subtype angiotensin receptor blocker, attenuated the hypertrophic response and suppressed the activation of MAP kinases in

ACE2
−/y

mice. Activation of MAP kinases in response to angiotensin II was greater in cardiomyocytes isolated from

ACE2
−/y

mice than in those isolated from WT mice. ACE2 plays an important role in dampening the hypertrophic response to pressure overload mediated by angiotensin II. Disruption of this regulatory function may accelerate cardiac hypertrophy and shorten the transition period from compensated hypertrophy to cardiac failure.
Reactivity of Ambulatory Blood Pressure to Physical Activity Varies With Time of Day
Authors: Jones Helen , Atkinson Greg , Leary Andrew , George Keith , Murphy Michael , Waterhouse Jim
Published: February 2006

Blood pressure (BP) fluctuates over a 24-hour period, but it is unclear to what extent this variation is governed completely by changes in physical activity. Our aim was to use a BP “reactivity index” to investigate whether the BP response to a given level of physical activity changes during a normal sleep-wake cycle. Hypertensive patients (n=440) underwent simultaneous 24-hour ambulatory BP, heart rate (HR), and activity monitoring. BP and HR were measured every 20 minutes. Actigraphy data were averaged over the 15 minutes that preceded a BP measurement. Individual BP and HR reactivity indices were calculated using least-squares regression for twelve 2-hour periods. These indices were then analyzed for time-of-day differences using a general linear model. Systolic BP and HR were generally more reactive to physical activity than diastolic BP. The highest reactivity of systolic BP (mean±SE=4±1 mm Hg per logged unit change in activity) was observed between 8:00
am
and 10:00
am
(
P
=0.014). Between 10:00
am
and 12:00
pm
, BP reactivity then decreased (
P
=0.048) and showed a secondary rise in the early afternoon. These 24-hour changes in BP reactivity did not differ significantly between groups formed on the basis of early and late wake times (
P
=0.485), medication use, age, and sex (
P
>0.350). In conclusion, under conditions of normal living, the reactivity of BP and HR to a given unit change in activity is highest in the morning and shows a secondary rise in the afternoon.
Gene Transfer of Hepatocyte Growth Factor Gene Improves Learning and Memory in the Chronic Stage of Cerebral Infarction
Authors: Shimamura Munehisa , Sato Naoyuki , Waguri Satoshi , Uchiyama Yasuo , Hayashi Takuya , Iida Hidehiro , Nakamura Toshikazu , Ogihara Toshio , Kaneda Yasufumi , Morishita Ryuichi
Published: February 2006

There is no specific treatment to improve the functional recovery in the chronic stage of ischemic stroke. To provide the new therapeutic options, we examined the effect of overexpression of hepatocyte growth factor (HGF) in the chronic stage of cerebral infarction by transferring the HGF gene into the brain using hemagglutinating virus of Japan envelope vector. Sixty rats were exposed to permanent middle cerebral artery occlusion (day 1). Based on the sensorimotor deficits at day 7, the rats were divided equally into control vector or HGF-treated rats. At day 56, rats transfected with the HGF gene showed a significant recovery of learning and memory in Morris water maze tests (control vector 50±4 s; HGF 33±5 s;
P
<0.05) and passive avoidance task (control vector 132.4±37.5 s; HGF 214.8±26.5 s;
P
<0.05). Although the total volume of cerebral infarction was not related to the outcome, immunohistochemical analysis for Cdc42 and synaptophysin in the peri-infarct region revealed that HGF enhanced the neurite extension and increased synapses. Immunohistochemistry for glial fibriary acidic protein revealed that the formation of glial scar was also prevented by HGF gene treatment. Additionally, the number of the arteries was increased in the HGF group at day 56. These data demonstrated that HGF has a pivotal role for the functional recovery after cerebral infarction through neuritogenesis, improved microcirculation, and the prevention of gliosis. Our results also provide evidence for the feasibility of gene therapy in the chronic stage of cerebral infarction.
Targeted Deletion of Matrix Metalloproteinase 2 Ameliorates Myocardial Remodeling in Mice With Chronic Pressure Overload
Authors: Matsusaka Hidenori , Ide Tomomi , Matsushima Shouji , Ikeuchi Masaki , Kubota Toru , Sunagawa Kenji , Kinugawa Shintaro , Tsutsui Hiroyuki
Published: February 2006

Matrix metalloproteinases (MMPs) play an important role in the extracellular matrix remodeling. Experimental and clinical studies have demonstrated that MMP 2 and 9 are upregulated in the dilated failing hearts and involved in the development and progression of myocardial remodeling. However, little is known about the role of MMPs in mediating adverse myocardial remodeling in response to chronic pressure overload (PO). We, thus, hypothesized that selective disruption of the MMP 2 gene could ameliorate PO-induced cardiac hypertrophy and dysfunction in mice. PO hypertrophy was induced by transverse aortic constriction (TAC) in male MMP 2 knockout (KO) mice (n=10) and sibling wild-type (WT) mice (n=9). At 6 weeks, myocardial MMP 2 zymographic activity was 2.4-fold increased in WT+TAC, and this increase was not observed in KO+TAC, with no significant alterations in other MMPs (MMP 1, 3, 8, and 9) or tissue inhibitors of MMPs (1, 2, 3, and 4). TAC resulted in a significant increase in left ventricular (LV) weight and LV end-diastolic pressure (EDP) with preserved systolic function. KO+TAC mice exerted significantly lower LV weight/body weight (4.2±0.2 versus 5.0±0.2 mg/g;
P
<0.01), lung weight/body weight (4.9±0.2 versus 6.2±0.4 mg/g;
P
<0.01), and LV end-diastolic pressure (4±1 versus 10±2 mm Hg;
P
<0.05) than WT+TAC mice despite comparable aortic pressure. KO+TAC mice had less myocyte hypertrophy (cross-sectional area; 322±14 versus 392±14 μm
2
;
P
<0.01) and interstitial fibrosis (collagen volume fraction; 3.3±0.5 versus 8.2±1.0%;
P
<0.01) than WT+TAC mice. MMP 2 plays an important role in PO-induced LV hypertrophy and dysfunction. The inhibition of MMP 2 activation may, therefore, be a useful therapeutic strategy to manage hypertensive heart disease.
Prevention of Syncope Trial (POST)
Authors: Sheldon Robert , Connolly Stuart , Rose Sarah , Klingenheben Thomas , Krahn Andrew , Morillo Carlos , Talajic Mario , Ku Teresa , Fouad-Tarazi Fetnat , Ritchie Debbie , Koshman Mary-Lou
Published: February 2006

Background—

Previous studies that assessed the effects of β-blockers in preventing vasovagal syncope provided mixed results. Our goal was to determine whether treatment with metoprolol reduces the risk of syncope in patients with vasovagal syncope.

Methods and Results—

The multicenter Prevention of Syncope Trial (POST) was a randomized, placebo-controlled, double-blind, trial designed to assess the effects of metoprolol in vasovagal syncope over a 1-year treatment period. Two prespecified analyses included the relationships of age and initial tilt-test results to any benefit from metoprolol. All patients had >2 syncopal spells and a positive tilt test. Randomization was stratified according to ages <42 and ≥42 years. Patients received either metoprolol or matching placebo at highest-tolerated doses from 25 to 200 mg daily. The main outcome measure was the first recurrence of syncope. A total of 208 patients (mean age 42±18 years) with a median of 9 syncopal spells over a median of 11 years were randomized, 108 to receive metoprolol and 100 to the placebo group. There were 75 patients with ≥1 recurrence of syncope. The likelihood of recurrent syncope was not significantly different between groups. Neither the age of the patient nor the need for isoproterenol to produce a positive tilt test predicted subsequent significant benefit from metoprolol.

Conclusions—

Metoprolol was not effective in preventing vasovagal syncope in the study population.
Receptor for Advanced-Glycation End Products
Authors: Bucciarelli Loredana G. , Kaneko Michiyo , Ananthakrishnan Radha , Harja Evis , Lee Larisse K. , Hwang Yuying C. , Lerner Shulamit , Bakr Soliman , Li Qing , Lu Yan , Song Fei , Qu Wu , Gomez Teodoro , Zou Yu Shan , Yan Shi Fang , Schmidt Ann Marie , Ramasamy Ravichandran
Published: February 2006

Background—

The beneficial effects of reperfusion therapies have been limited by the amount of ischemic damage that occurs before reperfusion. To enable development of interventions to reduce cell injury, our research has focused on understanding mechanisms involved in cardiac cell death after ischemia/reperfusion (I/R) injury. In this context, our laboratory has been investigating the role of the receptor for advanced-glycation end products (RAGE) in myocardial I/R injury.

Methods and Results—

In this study we tested the hypothesis that RAGE is a key modulator of I/R injury in the myocardium. In ischemic rat hearts, expression of RAGE and its ligands was significantly enhanced. Pretreatment of rats with sRAGE, a decoy soluble part of RAGE receptor, reduced ischemic injury and improved functional recovery of myocardium. To specifically dissect the impact of RAGE, hearts from homozygous RAGE-null mice were isolated, perfused, and subjected to I/R. RAGE-null mice were strikingly protected from the adverse impact of I/R injury in the heart, as indicated by decreased release of LDH, improved functional recovery, and increased adenosine triphosphate (ATP). In rats and mice, activation of the RAGE axis was associated with increases in inducible nitric oxide synthase expression and levels of nitric oxide, cyclic guanosine monophosphate (cGMP), and nitrotyrosine.

Conclusions—

These findings demonstrate novel and key roles for RAGE in I/R injury in the heart. The findings also demonstrate that the interaction of RAGE with advanced-glycation end products affects myocardial energy metabolism and function during I/R.
Apoptosis Repressor With Caspase Recruitment Domain Is Required for Cardioprotection in Response to Biomechanical and Ischemic Stress
Authors: Donath Stefan , Li Peifeng , Willenbockel Christian , Al-Saadi Nidal , Gross Volkmar , Willnow Thomas , Bader Michael , Martin Ulrich , Bauersachs Johann , Wollert Kai C. , Dietz Rainer , von Harsdorf Rüdiger
Published: February 2006

Background—

Ischemic heart disease and heart failure are associated with an increased loss of cardiomyocytes due to apoptosis. Whether cardiomyocyte apoptosis plays a causal role in the pathogenesis of heart failure remains enigmatic. The apoptosis repressor with caspase recruitment domain (ARC) is a recently discovered antiapoptotic factor with a highly specific expression pattern in striated muscle and neurons. ARC is a master regulator of cardiac death signaling because it is the only known factor that specifically inhibits both the intrinsic and extrinsic apoptotic death pathway. In this study we attempted to elucidate the physiological role of ARC and to understand pathophysiological consequences resulting from its deletion.

Methods and Results—

We generated ARC-deficient mice, which developed normally to adulthood and had no abnormality in cardiac morphology and function under resting conditions. On biomechanical stress induced by aortic banding, ARC-deficient mice developed accelerated cardiomyopathy compared with littermate controls, which was characterized by reduced contractile function, cardiac enlargement, and myocardial fibrosis. Likewise, ischemia/reperfusion injury of ARC-deficient mice resulted in markedly increased myocardial infarct sizes. Although in both instances a significant increase in apoptotic cardiomyocytes could be observed in ARC-deficient mice, neither in vitro nor in vivo studies revealed any effect of ARC on classic hypertrophic cardiomyocyte growth responses. The pathophysiological relevance of downregulated ARC levels was underscored by specimens from failing human hearts showing markedly reduced ARC protein levels.

Conclusions—

Our study identifies a tissue-specific antiapoptotic factor that is downregulated in human failing myocardium and that is required for cardioprotection in pressure overload and ischemia.
Mutations in Desmoglein-2 Gene Are Associated With Arrhythmogenic Right Ventricular Cardiomyopathy
Authors: Pilichou Kalliopi , Nava Andrea , Basso Cristina , Beffagna Giorgia , Bauce Barbara , Lorenzon Alessandra , Frigo Gianfranco , Vettori Andrea , Valente Marialuisa , Towbin Jeffrey , Thiene Gaetano , Danieli Gian Antonio , Rampazzo Alessandra
Published: February 2006

Background—

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by progressive myocardial atrophy with fibrofatty replacement. The recent identification of causative mutations in plakoglobin, desmoplakin (DSP), and plakophilin-2 (PKP2) genes led to the hypothesis that ARVC is due to desmosomal defects. Therefore, desmoglein-2 (DSG2), the only desmoglein isoform expressed in cardiac myocytes, was screened in subjects with ARVC.

Methods and Results—

In a series of 80 unrelated ARVC probands, 26 carried a mutation in DSP (16%), PKP2 (14%), and transforming growth factor-β3 (2.5%) genes; the remaining 54 were screened for DSG2 mutations by denaturing high-performance liquid chromatography and direct sequencing. Nine heterozygous DSG2 mutations (5 missense, 2 insertion-deletions, 1 nonsense, and 1 splice site mutation) were detected in 8 probands (10%). All probands fulfilled task force criteria for ARVC. An endomyocardial biopsy was obtained in 5, showing extensive loss of myocytes with fibrofatty tissue replacement. In 3 patients, electron microscopy investigation was performed, showing intercalated disc paleness, decreased desmosome number, and intercellular gap widening.

Conclusions—

This is the first investigation demonstrating DSG2 gene mutations in a significant number of ARVC-unrelated probands. Cardiac phenotype is characterized clinically by typical ARVC features with frequent left ventricular involvement and morphologically by fibrofatty myocardial replacement and desmosomal remodeling. The presence of mutations in desmosomal encoding genes in 40% of cases confirms that many forms of ARVC are due to alterations in the desmosome complex.
Blocking the Protease-Activated Receptor 1-4 Heterodimer in Platelet-Mediated Thrombosis
Authors: Leger Andrew J. , Jacques Suzanne L. , Badar Jehangir , Kaneider Nicole C. , Derian Claudia K. , Andrade-Gordon Patricia , Covic Lidija , Kuliopulos Athan
Published: February 2006

Background—Thrombin is the most potent agonist of platelets and plays a critical role in the development of arterial thrombosis. Human platelets express dual thrombin receptors, protease-activated receptor (PAR) 1 and PAR4; however, there are no therapeutic strategies that effectively target both receptors.

Methods and Results—Platelet aggregation studies demonstrated that PAR4 activity is markedly enhanced by thrombin–PAR1 interactions. A combination of bivalirudin (hirulog) plus a novel PAR4 pepducin antagonist, P4pal-i1, effectively inhibited aggregation of human platelets to even high concentrations of thrombin and prevented occlusion of carotid arteries in guinea pigs. Likewise, combined inhibition of PAR1 and PAR4 with small-molecule antagonists and pepducins was effective against carotid artery occlusion. Coimmunoprecipitation and fluorescence resonance energy transfer studies revealed that PAR1 and PAR4 associate as a heterodimeric complex in human platelets and fibroblasts. PAR1-PAR4 cofactoring was shown by acceleration of thrombin cleavage and signaling of PAR4 on coexpression with PAR1.

Conclusions—We show that PAR1 and PAR4 form a stable heterodimer that enables thrombin to act as a bivalent functional agonist. These studies suggest that targeting the PAR1-PAR4 complex may present a novel therapeutic opportunity to prevent arterial thrombosis.
Factor XIII Deficiency Causes Cardiac Rupture, Impairs Wound Healing, and Aggravates Cardiac Remodeling in Mice With Myocardial Infarction
Authors: Nahrendorf Matthias , Hu Kai , Frantz Stefan , Jaffer Farouc A. , Tung Ching-Hsuan , Hiller Karl-Heinz , Voll Sabine , Nordbeck Peter , Sosnovik David , Gattenlöhner Stefan , Novikov Mikhail , Dickneite Gerhard , Reed Guy L. , Jakob Peter , Rosenzweig Anthony , Bauer Wolfgang R. , Weissleder Ralph , Ertl Georg
Published: February 2006

Background—

Identification of key molecular players in myocardial healing could lead to improved therapies, reduction of scar formation, and heart failure after myocardial infarction (MI). We hypothesized that clotting factor XIII (FXIII), a transglutaminase involved in wound healing, may play an important role in MI given prior clinical and mouse model data.

Methods and Results—

To determine whether a truly causative relationship existed between FXIII activity and myocardial healing, we prospectively studied myocardial repair in FXIII-deficient mice. All FXIII
−/−
and FXIII
−
/+
(FXIII activity <5% and 70%) mice died within 5 days after MI from left ventricular rupture. In contradistinction, FXIII
−/−
mice that received 5 days of intravenous FXIII replacement therapy had normal survival rates; however, cardiac MRI demonstrated worse left ventricular remodeling in these reconstituted FXIII
−/−
mice. Using a FXIII-sensitive molecular imaging agent, we found significantly greater FXIII activity in wild-type mice and FXIII
−/−
mice receiving supplemental FXIII than in FXIII
−/−
mice (
P
<0.05). In FXIII
−/−
but not in reconstituted FXIII
−/−
mice, histology revealed diminished neutrophil migration into the MI. Reverse transcriptase–polymerase chain reaction studies suggested that the impaired inflammatory response in FXIII
−/−
mice was independent of intercellular adhesion molecule and lipopolysaccharide-induced CXC chemokine, both important for cell migration. After MI, expression of matrix metalloproteinase-9 was 650% higher and collagen-1 was 53% lower in FXIII
−/−
mice, establishing an imbalance in extracellular matrix turnover and providing a possible mechanism for the observed cardiac rupture in the FXIII
−/−
mice.

Conclusions—

These data suggest that FXIII has an important role in murine myocardial healing after infarction.
Comparative morphological and serological studies of three Anatolian Mountain frogs, Rana macrocnemis, R. camerani and R. holtzi (Anura, Ranidae)
Authors: Atatür Mehmet Kutsay , Kaya Uğur , Arikan Hüseyin , Çevik İbrahim Ethem
Published: February 2006

Three currently recognized species of Anatolian mountain frogs were analyzed for species boundaries. Meristic and proportional measurement data of three populations, including two topotypical ones, were evaluated using both univariate and discriminant analyses, and blood-serum samples were analyzed electrophoretically with polyacrylamide-disc electrophoresis. The results indicate that only two distinct mountain frog species inhabit Anatolia. We recommend that R. camerani from Mt Erciyes should be recognized as a synonym of R. macrocnemis.
The Phylogenetic Relationships of the Chinese and Vietnamese Waterfall frogs of the genus Amolops
Authors: Orlov Nikolai , Murphy Robert , Liu Wanzhao , Ngo Andre , Lathrop Amy
Published: February 2006

Ranid frogs of the genus Amolops occur in Southeast Asia and are typically found near waterfalls. Their phylogenetic relationships have not been resolved. We include 2,213 aligned nucleotide sites of the 12S, 16S and tRNAval gene regions of the mitochondrial DNA genome from 43 individuals of Chinese and Vietnamese Amolops, Huia, Hylarana, Meristogenys, Odorrana and Rana. The outgroup species were from the genera Chaparana, Limnonectes, Nanorana, and Paa. The data were analyzed within the framework of a refutationist philosophy using maximum parsimony. Four clades of waterfall frogs were resolved. Meristogenys was not resolved as the sister group to either Huia nor Amolops. The hypothesis of evolutionary relationships placed Amolops chapaensis and Huia nasica in the genus Odorrana.
Variable number tandem repeats in the mitochondrial DNA Control region of the Chinese alligator, Alligator sinensis
Authors: Fang Shengguo , Xu Qianghua
Published: February 2006

Variable number tandem repeats (VNTRs) are present in the control region of mitochondrial DNA (mtDNA) of the alligatorid species; however, the evolutionary dynamics of the repetitive sequences and the significance of the VNTRs in the context of genetic monitoring of these species are not well explored. The Chinese alligator, Alligator sinensis is critically endangered and is now largely in captive breeding. Previous studies in mitochondrial genes revealed little genetic diversity existing within the populations. We reported here the structural variation and evolutionary features of mtVNTRs in the Changxing population of the species. The mtVNTRs contained 676∼785 base pairs, made up by 5 distinct motifs repeated 31∼36 times in 32 individuals examined. The motifs were 21∼22 nts in length, with high sequence similarity between each other and with those of the American alligator (Alligator mississippiensis), indicating origination of the mtVNTRs from a single ancestral duplication unit in both species. The 5′ and 3′ portions of the repetitive sequences in the Chinese alligator were very much conserved among the individuals, while those in the middle showed a higher degree of sequence variation. The frequency of each motif appearing in the mtVNTRs showed positive correlation to the binding energy of the potential secondary structure the motif could adopt. 17 VNTR types, of which, 6 from the second generation and 12 from the third generation were identified from the samples. Analysis of the multiple VNTR types showed a high level of stochastic mutation within each generation. The suitability of the mtVNTRs as a marker to monitor the genetic differentiation of the Chinese alligator was also discussed.
Hemipenial morphology of five Asian pitvipers, with a discussion on their taxonomy
Authors: Guo Peng , Zhao Hui , Zhao Ermi , Lu Shunqing , Huang Song
Published: February 2006

The hemipenial morphology of five Asian pitvipers, Protobothrops mucrosquamatus, Protobothrops jerdonii, Ovophis zayuensis, Ovophis monticola and Viridovipera yunnanensis, are described and illustrated. Of them, the hemipenes of the first three species have been briefly reported in Chinese Journal of Zoology in Chinese. The results reveal that five species are different in hemipenial structures. The differences between Ovophis zayuensis and Ovophis monticola, and between Viridovipera yunnanensis and Viridovipera stejnegeri, further confirm the validation of Ovophis zayuensis and Viridovipera yunnanensis respectively.
Rod-Shaped Bivalents indicate new assemblage among Anatolian Water Frog Populations
Authors: Mutaf Beria Falakali , Keskin Nurşen Alpagut
Published: February 2006

The general features of the mitotic and meiotic chromosomes analysed in 91 frogs belonging to nine water frog populations distributed in Southwest Anatolia. The differences found in mitotic and meiotic chromosomes revealed the existence of two groups among the populations: the first "Aegean Group" includes those from Izmir, Bulca, Pazarağaç, and the second – "Lake District Group" from Eber, Akşehir, Gelendost, Eğirdir, Gölcük, and Beyşehir populations. The major distinction appeared in the number of the rod-shaped bivalents in metaphase I, with only one in the "Aegean Group" compared to one or two in the "Lake District Group". This result indicates a new assemblage among Anatolian water frogs and strengthens the suggestion that the "Lake District Group" that have one or two rod shaped bivalents in metaphase I due to the inclusion of hybrid lineages containing both parental genomes. It is clear that at least two separate species are present in Anatolia; one of them is possibly Rana ridibunda from the north and the second is closer to the Balkan species Rana epeirotica and Rana shqiperica.
Asynchronous spermatogenesis and biennial female cycle of the viviparous lizard Phymaturus antofagastensis (Liolaemidae): reproductive responses to high altitudes and temperate climate of Catamarca, Argentina
Authors: Ibargüengoytía Nora , Boretto Jorgelina
Published: February 2006

This paper studies minimum SVL at sexual maturity, sexual dimorphism, operational sex ratio, male and female reproductive cycles, and litter size of viviparous Phymaturus antofagastensis, a species living at high altitude in the temperate climate of Catamarca, Argentina. Males reached sexual maturity at 90 mm, and females at 79 mm. Adult males attained significantly larger body size and head width than adult females. Histological analysis showed asynchrony in spermatogenesis timing among males and spermatozoa storage in epididymis throughout the reproductive season (spring to early autumn). Females showed a biennial reproductive cycle taking at least one activity season to perform either vitellogenesis or pregnancy. Brood size resulted in two offspring, a condition similar to other species of the genus, with births occurring in late summer. The reproductive cycle of Phymaturus antofagastensis shows a new response in males and females to harsh environments characterized by short activity seasons, long hibernation periods and large daily and seasonal thermal fluctuations.
Interpopulational variation in sexual dimorphism, reproductive output, and parasitism of Liophis miliaris (Colubridae) in the Atlantic forest of Brazil
Authors: Pizzatto Lígia , Marques Otavio
Published: February 2006

Sexual maturity, sexual dimorphism, reproductive output, and parasitism of the colubrid snake Liophis miliaris were compared among populations inhabiting four regions of Brazil: (1) northern coastal Atlantic forest, (2) southern coastal Atlantic forest, (3) northern inland Atlantic forest (4) southern inland Atlantic forest. Females delayed maturity and attained larger body sizes than males in all regions. Males and females from northern Atlantic forest were smaller and attained maturity with a smaller body size than males of other regions. The sexual size dimorphism index ranged from 0.19 to 0.23 and was lowest in the northern Atlantic forest. There was no sexual dimorphism in head length in any of the populations studied. Clutch size was similar in all populations and increased with maternal body size. The reproductive frequency was lower in the northern coastal Atlantic forest and in contrast to the other regions, tended to increase with female body size. The nematoda Ophidiascaris sp. and cystacanths of Oligacanthorynchus spira (Acanthocephala) occurred equally in both sexes. Fewer snakes from the northern coastal Atlantic forest were infested by parasites compared to the other regions and parasitism apparently did not influence reproduction.
Insular morphological divergence in the lizard Liolaemus pictus (Liolaemidae)
Authors: Méndez Marco , Veloso Alberto , Vidal Marcela
Published: February 2006

Liolaemus pictus is a widely distributed arboreal lizard species in southern Chile. Within this species, mainland and island subspecies have been described mainly based on external morphological characters, however, their diagnostic characters have not been accurately demarcated. We used both traditional and geometric morphometrics to study the morphological divergence in L. pictus subspecies. Since geographic isolation can be related to environmental variation (e.g., variation in abundance and richness of insects or fruits), we predict that the L. pictus morphology could vary in head shape between mainland and island localities.Our results show morphological divergence in all variables analyzed among the island and mainland localities. The traditional morphometric approach reveals differences between populations from the mainland and island localities, where the mainland populations show a larger head size. Geometric morphometric data indicate that the eye orbits of the island specimens are more extended than in the mainland specimens in the dorsal view; this is probably related to a different capacity of substrate used. Also, in the lateral view, the eye orbits are extended and the head shape is less dorso-ventrally compressed in the island locality than in mainland populations and the terminal mouth position is more posterior in island specimens. We suggest that the morphological variation between mainland and island localities could be related to the fact that these populations were isolated during the last maximum glacial period in southern Chile, a period in which geomorphologic and bioclimatic features of this area were modified forming the present archipelago.
Potential use of anurans as indicators of biological quality in upstreams of central Italy
Authors: Lebboroni Marco , Chelazzi Guido , Bellavita Massimo , Ricchiardino Giulia
Published: February 2006

The headwater streams of two basins in central Italy were sampled in randomly selected reaches (n = 59) to quantify tadpole occurrence. Environmental and physico-chemical data were collected for each reach. Macrobenthos were also sampled to obtain quantitative indices of biological quality (IBE and BMWP). A longitudinal zonation was evident for the three most common amphibian species found (Rana italica, Bufo bufo and Rana kl. esculenta, from higher to lower altitude). A good concordance was recorded between the occurence of single species, in this order, and a decreasing value of water quality as computed by BMWP. In both basins, the average BMWP and IBE scores for reaches where R. italica occurred alone corresponded to the standard judgement of 'excellent' to 'good' biological water quality. R. italica was suggested as a potential bioindicator for small headwater streams.
Allometry of reproduction of Podocnemis expansa in Southern Amazon basin
Authors: Piña Carlos , Bonach Kelly , Verdade Luciano
Published: February 2006

Podocnemis expansa (giant Amazon freshwater turtle) is the biggest freshwater turtle of South America. Like in other reptiles, the nest of P. expansa is a hole in the sand deep enough to avoid predators and extremes of temperature and humidity. However, nesting habitat selection in reptiles has effects on incubation success and on hatchlings. Female body-size is also related to the size and shape (i.e., form) of the nest, which might in theory be related to the female reproductive success. In this study we established allometric relationships between female body size and nest form. Fieldwork was carried out in nesting beaches of Araguaia and Crixás-Açu Rivers in Southern Amazon basin, Brazil, from September to December 2000. As a result, we can establish that nest form does not affect reproductive success in the species, but female body length is positively related to egg mass and clutch size.
Negotiating Measures to Manage Biological Risks: The Need for New Thinking and New Approaches
Authors: Moodie Michael
Published: March 2006

This essay considers the difficulties confronting the international community in addressing the challenge of biological weapons through multilateral negotiations. After a brief review of the Biological and Toxin Weapons Convention, the article addresses four categories of factors that help understand the relative lack of success: those related to the structure and conduct of the negotiating process, those stemming from the unique nature of the life sciences, those associated with domestic political dynamics in the United States, and those associated with changes in the structure and dynamics of the international system. It closes with reflections on how the international community can embed negotiations in a broader strategy for bolstering capabilities to manage the security risks related to the advances of the life sciences and related technology.
Realism, Politics and Culture in Middle East Arms Control Negotiations
Authors: Steinberg Gerald
Published: March 2006

The history of arms control efforts in the Middle East consists of numerous initiatives, but very limited results. From the first efforts to negotiate WMD limits and non-proliferation arrangements in the 1960s, through various regional initiatives, frameworks, proposals, discussions, and negotiations, the obstacles to agreement on mutual limitations remained dominant. Frequent discussions in the UN of a Middle East Nuclear Free Zone (MENWFZ), the multi-lateral Arms Control and Regional Security (ACRS) talks initiated during the 1991 Middle East Peace Conference, and the regional dimensions of global frameworks such as the NPT, CWC, and CTBT have all failed to produce results.Detailed analysis of these efforts highlights the impact of realist security-based factors, the structure and process of the interactions, as well as the cultural and domestic political dimensions. The existential conflicts, reflected in protracted territorial disputes and denials of legitimacy and compounded by a fundamental asymmetry, created a zero-sum framework in the region. The region is characterized by a great deal of instability and competition; this situation, in turn, contributed to the efforts to acquire WMD. In terms of domestic politics, the regional cooperation required for arms limitation is often inconsistent with the dominant articulated political interests and regime perspectives. In addition, misunderstandings and misperceptions frequently occur due to the complexities of cross-cultural communications in the Middle East. Numerous dialogues have not narrowed the gaps or transformed the zero-sum frameworks into cooperative ones. Hopes for the creation of successful regional mechanisms for limiting arms depend on overcoming the obstacles encountered in past efforts.
Association of Tropical Cirrus in the 10–15-km Layer with Deep Convective Sources: An Observational Study Combining Millimeter Radar Data and Satellite-Derived Trajectories
Authors: Mace Gerald G. , Deng Min , Soden Brian , Zipser Ed
Published: March 2006

In this paper, millimeter cloud radar (MMCR) and Geosynchronous Meteorological Satellite (GMS) data are combined to study the properties of tropical cirrus that are common in the 10–15-km layer of the tropical troposphere in the western Pacific. Millimeter cloud radar observations collected by the Atmospheric Radiation Measurement program on the islands of Manus and Nauru in the western and central equatorial Pacific during a 12-month period spanning 1999 and 2000 show differences in cirrus properties: over Manus, where clouds above 7 km are observed 48% of the time, the cirrus are thicker and warmer on average and the radar reflectivity and Doppler velocity are larger; over Nauru clouds above 7 km are observed 23% of time. To explain the differences in cloud properties, the relationship between tropical cirrus and deep convection is examined by combining the radar observations with GMS satellite-derived back trajectories. Using a data record of 1 yr, it is found that 47% of the cirrus observed over Manus can be traced to a deep convective source within the past 12 h while just 16% of the cirrus observed over Nauru appear to have a convective source within the previous 12 h. Of the cirrus that can be traced to deep convection, the evolution of the radar-observed cloud properties is examined as a function of apparent cloud age. The radar Doppler moments and ice water path of the observed cirrus at both sites generally decrease as the cirrus age increase. At Manus, it is found that cirrus during boreal winter typically advect over the site from the southeast from convection associated with the winter monsoon, while during boreal summer, the trajectories are mainly from the northeast. The properties of these two populations of cirrus are found to be different, with the winter cirrus having higher concentrations of smaller particles. Examining statistics of the regional convection using Tropical Rainfall Measuring Mission (TRMM), it is found that the properties of the winter monsoon convection in the cirrus source region are consistent with more intense convection compared to the convection in the summer source region.
Vortex–Vortex Interactions in the Winter Stratosphere
Authors: Scott R. K. , Dritschel D. G.
Published: March 2006

This paper examines the interaction of oppositely signed vortices in the compressible (non-Boussinesq) quasigeostrophic system, with a view to understanding vortex interactions in the polar winter stratosphere. A series of simplifying approximations leads to a two-vortex system whose dynamical properties are determined principally by two parameters: the ratio of the circulation of the vortices and the vertical separation of their centroids. For each point in this two-dimensional parameter space a family of equilibrium solutions exists, further parameterized by the horizontal separation of the vortex centroids, which are stable for horizontal separations greater than a critical value. The stable equilibria are characterized by vortex deformations that generally involve stronger deformations of the larger and/or lower of the two vortices. For smaller horizontal separations, the equilibria are unstable and a strongly nonlinear, time-dependent interaction takes place, typically involving the shedding of material from the larger vortex while the smaller vortex remains coherent. Qualitatively, the interactions resemble previous observations of certain stratospheric sudden warmings that involved the interaction of a growing anticyclonic circulation with the cyclonic polar vortex.