bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel electrochemical approach to the characterization of oxidoreductase reactions
Authors: Ikeda Tokuji
Published: July 2004

Electrochemical methods based on enzyme‐electrochemical reactions have been developed for studying oxidoreductase reactions. The methods measure a current resulting from an oxidoreductase reaction with an electrode serving as a final electron acceptor (or donor) in the reaction. A theoretical equation for the enzyme‐electrochemical reaction, called bioelectrocatalysis, is derived, which enables kinetic analysis of the reaction. In combination with spectrophotometry, the electrochemical method provides a method for determining the redox potentials of proteins and enzymes. An alternative method based on bulk electrolysis in a quartz cell for UV‐vis spectroscopy has been developed for the measurements of protein redox potentials on a conventional spectrophotometer. The electrochemical methods are applied to kinetic and thermodynamic analyses for the reactions of a variety of enzymes including a newly discovered enzyme, quinohemoprotein amine dehydrogenase (QH‐AmDH), and bilirubin oxidase (BOD) [EC 1.3.3.5, from Myrothecium verrucaria], a copper‐containing enzyme useful for bioelectrocatalytic O2 reduction in biofuel cells. The electrochemical method for kinetic analysis has been successfully applied to the analysis of oxidoreductase reactions in vivo, as demonstrated by the reaction of glucose dehydrogenase in Escherichia coli. The advantages of the electrochemical methods are discussed. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 4: 192–203; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20014
Remote access virtual private network architecture for high‐speed wireless internet users
Authors: Elkeelany O. , Matalgah M. M. , Qaddour J.
Published: August 2004

The new emerging broadband wireless network (BWN) technologies with high‐speed wireless internet access promotes corporations to provide their roaming employees with high‐speed wireless access to the computing resources on their corporate networks. Thus, a value added service to broadband wireless network is the remote access virtual private network (VPN), where the corporate legitimate users can connect to their offices wirelessly from different locations and get secure services as if they were connected to the corporate local area network (LAN). One of the most important challenges is to block out illegitimate user requests, which are wirelessly received, to protect corporate privacy. Registration (adding new users) and authentication (accepting current users) functions should be implemented with highly secured wireless connection. These functions are accomplished by encapsulating (i.e. tunneling) the user information in a secured form to the corporate authentication server through the internet traffic. The corporate authentication server then grants or denies the user access. In this paper, we propose a new operational design algorithm for remote access wireless VPN authentication and registration protocols that depends on modifying tunnel establishment as compared to existing dial‐in VPN mechanisms. The modifications proposed in this paper are made to support successful deployment of the remote access VPN services over high‐speed wireless network. The paper presents an overview of two tunneling approaches using Layer 3 and Layer 2 separately for implementing these functions. Then we propose how we establish the tunnel in both approaches, and compare it to similar operation steps previously reported for the dial‐in VPN protocols. The proposed algorithms are distinguished from previously developed dial‐in VPN protocols by using L2TP and IPSEC instead of mobile IP. It is also shown that the steps involved in the establishment of the tunnel are functionally different and more appropriate to our applications using communication environment of the BWN. Finally, a qualitative analysis of the added functions, and a comparison between L2TP‐based and IPSec‐based approaches are established. Copyright © 2004 John Wiley & Sons, Ltd.
Fundamental limitations of power control and radio resource management in wireless networks
Authors: Gunnarsson Fredrik
Published: August 2004

The ultimate resource in wireless networks is transmission power. The system stability and the resource sharing algorithms all rely on well functioning power control. To realistically address resource management algorithms, it is important to consider fundamental limitations of the radio resource and of power control. Exact and approximate capacity expressions are derived and related to Quality of Service (QoS) requirements of services. Power control is subject to limited update rate, limited feedback bandwidth, time delays, measurement errors, feedback errors and filtering effects which all affect the resulting performance. Simulations further illustrate the hampering effects and motivates models of power control inaccuracies. Copyright © 2004 John Wiley & Sons, Ltd.
Sex‐related bedside clinical variables associated with survival of older inpatients with heart failure
Authors: Cohen Natan , Ilgiyaev Eduard , Almoznino‐Sarafian Dorit , Alon Irena , Shteinshnaider Miriam , Chachashvily Shulamit , Modai David , Gorelik Oleg
Published: August 2004

Background:

Little is known about sex‐related differences in factors affecting prognosis of heart failure (HF). We prospectively investigated the relationship between bedside clinical variables and survival of older females vs. males with HF.

Methods:

Included were consecutive unselected inpatients, age ≥60 years, admitted for various acute conditions. HF was chronic and of diverse etiologies. Follow‐up extended up to 5 years. All‐cause mortality was registered and statistically analyzed for association with in‐hospital clinical variables.

Results:

Included were 162 females and 200 males. Survival rates were 52.4% and 59%, respectively, (P=0.1). Advanced age and renal dysfunction (RD) were associated with low survival in both sexes (P<0.03 and 0.02, P<0.001 and 0.01, respectively). An association with low survival was found with respect to; admission for pulmonary edema (P<0.02), using furosemide ≥80 mg/day (P<0.005) and severe HF [NYHA class III–IV (P<0.01)] in females, as well as for hypokalemia (P<0.03) and hypocalcemia (P<0.03) in males. On multivariate analysis RD (P<0.001), increasing age (P=0.008) and furosemide dosage ≥80 mg (P=0.02) were most significantly associated with low survival in females, while RD only was significantly associated with low survival in males (P=0.03).

Conclusions:

Several clinical variables, which affect prognosis in older HF patients are sex‐related and probably carry practical significance.
Bedside tests of B‐type natriuretic peptide in the diagnosis of left ventricular diastolic dysfunction in hypertensive patients
Authors: Wei Tiemin , Zeng Chunlai , Chen Liping , Chen Qunying , Zhao Ruiying , Lu Ganxin , Lu Chunling , Wang Lexin
Published: August 2004

Aims:

To investigate the value of B‐type natriuretic peptide (BNP) in diagnosing left ventricular diastolic dysfunction in patients with hypertension.

Methods:

The left ventricular diastolic function and plasma BNP levels were assessed prospectively in 135 hypertensive patients.

Results:

The plasma BNP in patients with (n=61) and without (n=74) diastolic dysfunction was 122±105 and 18±16 pg/ml, respectively (p<0.001). Increased BNP levels were associated with systolic blood pressure (p<0.05), left ventricular mass index (p<0.001), the E/A ratio of transmitral flow (p<0.01) and the isovolumic relaxation time (p<0.01). A receiver‐operator characteristic curve showing the sensitivity and specificity of BNP against the echocardiography diagnosis of diastolic dysfunction revealed an area under the curve (accuracy) of 0.904 (p<0.01). Using a cut‐off value of >40 pg/ml, the sensitivity and specificity of plasma BNP in diagnosing left ventricular diastolic dysfunction were 79% and 92%, respectively.

Conclusions:

The plasma BNP levels in patients with hypertension are closely related to left ventricular hypertrophy and filling impairment. Plasma BNP may be used to facilitate the diagnosis of left ventricular diastolic dysfunction.
The effects of long‐term β‐blockade on the ventilatory responses to exercise in chronic heart failure
Authors: Witte Klaus K.A. , Thackray Simon , Nikitin Nikolay P. , Cleland John G.F. , Clark Andrew L.
Published: August 2004

Aims:

Chronic heart failure (CHF) patients complain of breathlessness and fatigue. Beta‐blockers improve symptoms, echocardiograpahic variables and prognosis in CHF, but their effect on exercise capacity remains unclear. The aim of this study was to describe the effects of long‐term beta‐blocker therapy on metabolic gas exchange variables and ventilation during exercise in CHF patients.

Methods:

42 patients with symptomatic heart failure due to left ventricular systolic dysfunction (ejection fraction 33.2 (8.2)) on loop diuretics and angiotensin‐converting enzyme inhibitors or angiotensin II antagonists, underwent exercise testing with metabolic gas exchange. They were then initiated onto and uptitrated to the maximum tolerated dose of beta‐blockers. After 1 year of follow‐up, patients were invited back for repeat testing.

Results:

35 patients attended for repeat exercise testing. Four patients had died, and three had not tolerated beta‐blockade. After 1 year, exercise time was increased (487 (221) vs. 500 (217), p<0.05), and peak oxygen consumption and VE/VCO2 slope were unchanged (20.9 (5.0) vs. 20.0 (5.4), p=0.15 and 36.7 (8.3) vs. 37.3 (7.8), p=0.70). Peak ventilation, (61.5 (12.9) vs. 57.1 (13.4), p<0.05), peak carbon dioxide production (1629 (404) vs. 1496 (375), p<0.02) and hence respiratory exchange ratio (1.02 (0.08) vs. 0.98 (0.06) p<0.02) and p<0.05) were reduced. Submaximal oxygen consumption and carbon dioxide production were lower at matched workloads. The slope relating symptoms to ventilation (Borg/VE slope) was less steep following beta‐blockade (0.18 (0.09) vs. 0.15 (0.06), p<0.05).

Conclusion:

Long term beta‐blocker therapy increases exercise time but not peak oxygen consumption, and reduces peak carbon dioxide production. CHF patients are less symptomatic for a given ventilation during exercise following beta‐blocker treatment.
Association of Ubc9, an E2 ligase for SUMO conjugation, with p53 is regulated by phosphorylation of p53
Authors: Lin Jye-Yee , Ohshima Takayuki , Shimotohno Kunitada
Published: August 2004

Small ubiquitin‐like modifier‐1 (SUMO‐1) conjugation to the tumor suppressor protein p53 seems to be regulated by murine double minute 2 homologue (Mdm2). It is thought that the physical association of Mdm2 with p53 is important for the enhancement of SUMO‐1 conjugation to p53. However, mutant p53 that does not associate with Mdm2 is still sumoylated, albeit at a reduced level, suggesting that sumoylation of p53 is independent of the presence of Mdm2 and there is a direct association of ubiquitin‐conjugating enzyme 9 (Ubc9), an E2 ligase for sumoylation, with p53. Here, we report evidence of the direct interaction of Ubc9 with p53. Furthermore, we observed that the interaction of Ubc9 with p53 was regulated by phosphorylation of p53. In particular, in cells treated with adriamycin that is a DNA damaging agent and that enhances phosphorylation of p53 at Ser‐20, SUMO conjugation of p53 was severely impaired possibly by reduced affinity of Ubc9 to p53.
In Arabidopsis thaliana, the invertase inhibitors AtC/VIF1 and 2 exhibit distinct target enzyme specificities and expression profiles
Authors: Link Manuela , Rausch Thomas , Greiner Steffen
Published: August 2004

Plant cell wall (CWI) and vacuolar invertases (VI) play important roles in carbohydrate metabolism, stress responses and sugar signaling. Addressing the regulation of invertase activities by inhibitor proteins (C/VIF, ell wall/acuolar nhibitor of ructosidase), we have identified two C/VIFs from Arabidopsis thaliana. AtC/VIF1 showed specific inhibition of VI activity, whereas AtC/VIF2 inhibited both, CWI and VI. Expression analysis revealed that expression of AtC/VIF1 was restricted to specific organs, AtC/VIF2, however, was weakly expressed throughout plant development. Promoter::GUS transformants confirmed pronounced differences of tissue/cell type‐specific expression between both isoforms. Growth of an AtC/VIF1 T‐DNA KO mutant was unaffected, but VI activity and hexose content were slightly increased.
New observations of sprites from the space shuttle
Authors: Yair Yoav , Israelevich Peter , Devir Adam D. , Moalem Meir , Price Colin , Joseph Joachim H. , Levin Zev , Ziv Baruch , Sternlieb Abraham , Teller Amit
Published: August 2004

We present the results of space‐based observations of sprites obtained during the Mediterranean Israeli Dust Experiment (MEIDEX) sprite campaign conducted on board the space shuttle Columbia during its STS‐107 mission in January 2003. A total of ∼6 hours of useful data were saved from 21 different orbits, of which 1/5 contained lightning. We imaged sprites from an altitude of 280 km using a calibrated multispectral camera above thunderstorms in various geographical locations, mainly in central Africa, northern Australia, and South America, and also over the Pacific and Indian Oceans. In this paper we report on sprites observed from ranges 1600–2000 km from the shuttle, at altitudes of 40–90 km above the ground. Their brightness was in the range of 0.3–1.7 mega‐Rayleighs (MR) in the 665 nm filter and 1.44–1.7 MR in the 860 nm filter. On the basis of the frequency of observed events and the number of tropical thunderstorms, we estimate the sprite rate in the tropics to be of the order of several per minute.
Annual dynamics of soil organic matter in the context of long‐term trends
Authors: Doane Timothy A. , Horwáth William R.
Published: August 2004

Long‐term research has provided a great deal of information regarding the influence of management on the equilibrium dynamics of soil organic matter (SOM), although short‐term dynamics remain largely uninvestigated. An improved approach to characterizing SOM dynamics in managed ecosystems would consider both short‐term and long‐term changes in content and composition. This approach and its implications are illustrated for an experimental site comparing agricultural management practices. Changes in soil C composition were assessed semiquantitatively using 13C natural abundance measurements, demonstrating their useful although rarely applied role in short‐term studies. This information is a valuable complement to long‐term data, since net differences since the site's inception fail to reveal a timeline marked by repeated changes in soil C content and composition. Such data are also useful for reinforcing and understanding long‐term simulation models, which are typically driven by temporally dynamic events but are often fit against temporally sparse SOM data sets.
Inhibition of Na+–H+ exchange by cariporide reduces inflammation and heart failure in rabbits with myocardial infarction
Authors: Rungwerth Katrin , Schindler Ursula , Gerl Martin , Schäfer Stefan , Licher Thomas , Busch Andreas E , Ruetten Hartmut
Published: July 2004

The aim of this study was to assess the effects of the Na+–H+ exchange inhibitor cariporide on left ventricular (LV) morphology and function as well as inflammation in rabbits with heart failure.

Rabbits with myocardial infarction (MI) and sham controls were randomized to receive either standard chow or chow supplemented with cariporide for 9 weeks. LV morphology was determined by echocardiography. LV systolic and diastolic function was assessed under load‐dependent and ‐independent conditions by analysis of LV pressure–volume loops using piezo‐electric crystals.

Plasma concentrations of C‐reactive protein and aldosterone were measured.

Rabbits with MI developed LV dilatation that was reduced by cariporide. Systolic and diastolic LV function was impaired in rabbits with MI when compared to sham, as indicated by a decreased dP/dtmax (MI: 3537±718 mmHg s−1, sham: 5839±247 mmHg s−1, P<0.05), the load‐independent preload recruitable stroke work (PRSW)(MI: 22±7 mmHg, sham: 81±23 mmHg, P<0.05) and a reduction in the time constant of relaxation tau (τ) (MI: 27±1 ms, sham: 17±1 ms, P<0.05), and significantly improved by cariporide (dP/dtmax: 4586±374 mmHg s−1, PRSW: 67±18 mmHg, τ: 20±2 ms; P<0.05 vs MI/control).

Induction of MI was associated with an increase in aldosterone and CRP, indicating activation of the neurohormonal and the inflammatory system that were largely reduced by cariporide.

Cariporide improves LV morphology and function post MI and suppresses inflammation and neurohormonal activation in congestive heart failure (CHF). Na+–H+ exchange inhibition may represent a new pharmaceutical approach for the treatment of CHF.

British Journal of Pharmacology (2004) 142, 1147–1154. doi:10.1038/sj.bjp.0705746
Vanilloid receptors mediate adrenergic nerve‐ and CGRP‐containing nerve‐dependent vasodilation induced by nicotine in rat mesenteric resistance arteries
Authors: Eguchi Shinji , Tezuka Satoko , Hobara Narumi , Akiyama Shinji , Kurosaki Yuji , Kawasaki Hiromu
Published: July 2004

Previous studies showed that nicotine induces adrenergic nerve‐dependent vasodilation that is mediated by endogenous calcitonin gene‐related peptide (CGRP) released from CGRP‐containing (CGRPergic) nerves. The mechanisms underlying the nicotine‐induced vasodilation were further studied.

Rat mesenteric vascular beds without endothelium were contracted by perfusion with Krebs solution containing methoxamine, and the perfusion pressure was measured with a pressure transducer.

Perfusion of nicotine (1–100 μM) for 1 min caused concentration‐dependent vasodilation. Capsazepine (vanilloid receptor‐1 antagonist; 1–10 μM) and ruthenium red (inhibitor of vanilloid response; 1–30 μM) concentration‐dependently inhibited the nicotine‐induced vasodilation without affecting the vasodilator response to exogenous CGRP.

Nicotine‐induced vasodilation was not inhibited by treatment with 3,4‐dihydroxyphenylalanine (DOPA) receptor antagonist (L‐DOPA cyclohexyl ester; 0.001–10 μM), dopamine D1 receptor‐selective antagonist (SCH23390; 1–10 μM), dopamine D2 receptor antagonist (haloperidol; 0.1–0.5 μM), ATP P2x receptor‐desensitizing agonist (α,β‐methylene ATP; 1–10 μM), adenosine A2 receptor antagonist (8(p‐sulfophenyl)theophylline; 10–50 μM) or neuropeptide Y (NPY)‐Y1 receptor antagonist (BIBP3226; 0.1–0.5 μM).

Immunohistochemical staining of the mesenteric artery showed dense innervation of CGRP‐ and vanilloid receptor‐1‐positive nerves, with both immunostainings appearing in the same neuron. The mesenteric artery was also densely innervated by NPY‐positive nerves. Double immunostainings showed that both NPY and CGRP immunoreactivities appeared in the same neuron of the artery.

These results suggest that nicotine acts on presynaptic nicotinic receptors to release adrenergic neurotransmitter(s) or related substance(s), which then stimulate vanilloid receptor‐1 on CGRPergic nerves, resulting in CGRP release and vasodilation.

British Journal of Pharmacology (2004) 142, 1137–1146. doi:10.1038/sj.bjp.0705773
KMUP‐1, a xanthine derivative, induces relaxation of guinea‐pig isolated trachea: the role of the epithelium, cyclic nucleotides and K+ channels
Authors: Wu Bin‐Nan , Lin Rong‐Jyh , Lo Yi‐Ching , Shen Kuo‐Pyng , Wang Chao‐Chuan , Lin Young‐Tso , Chen Ing‐Jun
Published: July 2004

7‐[2‐[4‐(2‐chlorophenyl)piperazinyl]ethyl]‐1,3‐dimethylxanthine (KMUP‐1) produces tracheal relaxation, intracellular accumulation of cyclic nucleotides, inhibition of phosphodiesterases (PDEs) and activation of K+ channels.

KMUP‐1 (0.01–100 μM) induced concentration‐dependent relaxation responses in guinea‐pig epithelium‐intact trachea precontracted with carbachol. Relaxation responses were also elicited by the PDE inhibitors theophylline, 3‐isobutyl‐1‐methylxanthine (IBMX), milrinone, rolipram and zaprinast (100 μM), and a KATP channel opener, levcromakalim.

Tracheal relaxation induced by KMUP‐1 was attenuated by epithelium removal and by pretreatment with inhibitors of soluble guanylate cyclase (sGC) (1H‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ), 1 μM), nitric oxide synthase (Nω‐nitro‐L‐arginine methyl ester, 100 μM), K+ channels (tetraethylammonium, 10 mM), KATP channels (glibenclamide, 1 μM), voltage‐dependent K+ channels (4‐aminopyridine, 100 μM) and Ca2+‐dependent K+ channels (charybdotoxin, 0.1 μM or apamin, 1 μM).

Both KMUP‐1 (10 μM) and theophylline nonselectively and slightly inhibited the enzyme activity of PDE3, 4 and 5, suggesting that they are able to inhibit the metabolism of adenosine 3′,5′‐cyclic monophosphate (cyclic AMP) and guanosine 3′,5′‐cyclic monophosphate (cyclic GMP). Likewise, the effects of IBMX were also measured and its IC50 values for PDE3, 4 and 5 were 6.5±1.2, 26.3±3.9 and 31.7±5.3 μM, respectively.

KMUP‐1 (0.01–10 μM) augmented intracellular cyclic AMP and cyclic GMP levels in guinea‐pig cultured tracheal smooth muscle cells. These increases in cyclic AMP and cyclic GMP were abolished in the presence of an adenylate cyclase inhibitor SQ 22536 (100 μM) and an sGC inhibitor ODQ (10 μM), respectively.

KMUP‐1 (10 μM) increased the expression of protein kinase A (PKARI) and protein kinase G (PKG1α1β) in a time‐dependent manner, but this was only significant for PKG after 9 h.

Intratracheal administration of tumour necrosis factor‐α (TNF‐α, 0.01 mg kg−1) induced bronchoconstriction and exhibited a time‐dependent increase in lung resistance (RL) and decrease in dynamic lung compliance (Cdyn). KMUP‐1 (1.0 mg kg−1), injected intravenously for 10 min before the intratracheal TNF‐α, reversed these changes in RL and Cdyn.

These data indicate that KMUP‐1 activates sGC, produces relaxation that was partly dependent on an intact epithelium, inhibits PDEs and increases intracellular cyclic AMP and cyclic GMP, which then increases PKA and PKG, leading to the opening of K+ channels and resulting tracheal relaxation.

British Journal of Pharmacology (2004) 142, 1105–1114. doi:10.1038/sj.bjp.0705791
Voltage‐dependent displacement of the scorpion toxin Ts3 from sodium channels and its implication on the control of inactivation
Authors: Campos Fabiana V , Coronas Fredy I V , Beirão Paulo S L
Published: July 2004

The voltage‐dependent displacement of the scorpion Tityus serrulatus α‐toxin Ts3 was investigated in native sodium channels of GH3 cells by examining the removal of its effects in toxin‐free solution.

Toxin at saturating concentration was pulsed (∼1 s) directly onto the cell, thus causing an eight‐fold increase of the slow component (τs=6 ms) of fast inactivation, and a three‐fold increase of the time constant of its fast component.

At 0 mV, maximal conductance was achieved in cells before and after treatment with Ts3, and no displacement of the toxin could be detected.

Toxin displacement occurred if stronger depolarising pulses (>100 mV) were applied. The rate of displacement depended on the amplitude and duration of the pulses, and was not related with outward Na+ flux.

We propose a model in which activation does not require complete movement of segment S4 of domain IV (IVS4) and that a more extensive movement of this segment is needed for normal fast inactivation. A kinetic model is presented that can account for the typical effects of site 3 toxins.

British Journal of Pharmacology (2004) 142, 1115–1122. doi:10.1038/sj.bjp.0705793
Requirement for flow in the blockade of endothelium‐derived hyperpolarizing factor (EDHF) by ascorbate in the bovine ciliary artery
Authors: Nelli Silvia , Dowell Fiona J , Wilson William S , Stirrat Alison , Martin William
Published: July 2004

We previously reported that ascorbate inhibits endothelium‐derived hyperpolarizing factor (EDHF)‐mediated vasodilatation in the bovine perfused ciliary circulation and rat perfused mesentery, but not in rings of bovine or porcine coronary artery.

In this study, we have compared the ability of ascorbate to inhibit EDHF‐mediated vasodilatation in a single vessel, the bovine long posterior ciliary artery, when perfused and when mounted as rings in a myograph.

Both in segments perfused at a flow rate of 2.5 ml min−1 and in rings mounted in a myograph, bradykinin and acetylcholine each induced vasodilator responses that were mediated jointly by EDHF and nitric oxide, as revealed by their respective blocking agents, apamin/charybdotoxin, and L‐NAME.

Ascorbate (50 and 150 μM) induced a time (max at 2–3 h)‐dependent inhibition of the EDHF‐mediated component of vasodilatation to bradykinin or acetylcholine in perfused segments, but not in rings.

Ascorbate (50 μM) failed to inhibit bradykinin‐induced vasodilatation at a flow rate of 1.25 ml min−1 or below, but produced graded blockade at the higher flow rates of 2.5 and 5 ml min−1. Furthermore, using a pressure myograph where pressure and flow were independently controlled, it was confirmed that the inhibitory action of ascorbate (150 μM) was directly related to flow per se and not any associated changes in pressure.

Thus, we have shown in the bovine ciliary artery that ascorbate inhibits EDHF‐mediated vasodilatation under conditions of flow but not in a static myograph. The mechanism by which flow renders EDHF susceptible to inhibition by ascorbate remains to be determined.

British Journal of Pharmacology (2004) 142, 1081–1090. doi:10.1038/sj.bjp.0705816
Aminoguanidine prevents age‐related deterioration in left ventricular–arterial coupling in Fisher 344 rats
Authors: Chang Kuo‐Chu , Hsu Kwan‐Lih , Chou Tsai‐Fwu , Lo Huey‐Ming , Tseng Yung‐Zu
Published: July 2004

In recent studies, aminoguanidine (AG), an inhibitor of advanced glycation endproducts, has been identified as a prominent agent that can prevent the age‐related aortic stiffening and cardiac hypertrophy. The aim of this study was to determine whether AG had effects on the left ventricular (LV)–arterial coupling in aged Fisher 344 rats in terms of the ventricular and arterial chamber properties.

Normotensive rats were treated from 18 to 24 months with AG (1 g l−1 in drinking water) and compared with a control group. LV pressure and ascending aortic flow signals were recorded to construct the ventricular and arterial end‐systolic pressure–stroke volume relationships to calculate LV end‐systolic elastance (Ees) and effective arterial volume elastance (Ea), respectively. The optimal afterload (Qload) determined by the ratio of Ea to Ees was used to measure the efficiency of mechanical energy transferred from the left ventricle to the arterial system.

In comparison with the 6‐month‐old rats, the 24‐month‐old animals had decreased Ees, at 567.4±26.7 vs 639.0±20.7 mmHg ml−1, decreased Ea, at 411.5±18.6 vs 577.9±15.7 mmHg ml−1, and decreased Qload, at 0.9428±0.0024 vs 0.9962±0.0014.

Treatment with AG for 6 months did not significantly affect Ees; however, when normalized to LV weight (i.e., Eesn=Ees/LV weight), Eesn showed a significant rise of 22.8%, suggesting that AG may retard the aging process on the intrinsic contractility of the left ventricle. On the other hand, the decrease in Ea in aging rats was prevented by AG, as reflected in the increase of 19.7% in this variable (P<0.05). The 24‐month‐old treated rats also exhibited a significant rise of 21.6% in Ea/Ees, causing an increase of 5.2% in Qload (P<0.05).

We conclude that in healthy older Fisher 344 rats without diabetes, long‐term treatment with AG may improve both the arterial and ventricular function and optimize the matching condition for the left ventricular–arterial coupling.

British Journal of Pharmacology (2004) 142, 1099–1104. doi:10.1038/sj.bjp.0705831
Evaluation of resistance to five isolates of Puccinia coronata f. sp. lolii in 19 perennial ryegrass cultivars
Authors: Clarke R. G. , Villalta O. N. , Hepworth G.
Published: August 2004

This paper seeks to provide information on the differences in resistance to
Puccinia coronata f. sp. lolii of
the many perennial ryegrass (Lolium perenne) cultivars
available in Australia, and on the variation in resistance to this pathogen
within these cultivars. This information will help farmers to select crown
rust resistant cultivars suited to their area, and indicate to perennial
ryegrass breeders the diversity of crown rust resistance within the cultivars
and lines screened. Twenty genotypes of 14 cultivars and 5 advanced breeding
lines of perennial ryegrass were screened for their reaction to 5 isolates of
P. coronata f. sp. lolii. The
isolates were collected from South Australia, southern Queensland, and 3
separate regions of Victoria. Tasdale, Victorian, Martlet, Tasmanian No. 1,
and D1 were significantly (P < 0�05) more
susceptible to crown rust than all other cultivars and lines. Embassy, D4, and
D16 were the most resistant of the 19 cultivars and lines screened. Within all
cultivars and lines there was significant (P P. coronata f. sp. lolii . This
type of screening for genotype reaction could enable differential test plants
to be selected for determining the presence of
P. coronata f. sp. lolii
pathotypes, an area that requires further research.
Pod set and seed yield as affected by cytokinin application and terminal drought in narrow-leafed lupin
Authors: Palta J. A. , Ludwig C.
Published: August 2004

An individual flower-painting technique that utilises
N6-benzylaminopurine (BAP) to increase pod set was used
on an indeterminate cultivar of narrow-leafed lupin
(Lupinus angustifolius L. cv. Merrit) and on a breeding
line with restricted branching (84A/241) to examine the interaction
between pod set, water deficit, and seed yield. Petals and sepals of each
flower on each inflorescence were painted with a 0·002 M solution of
BAP every day from the first day the flower opened to the day it senesced. A
water deficit was induced, after flowering on the first-order apical branch,
in half of the plants. The other half were maintained at a soil water content
close to field capacity. Leaf water potential and leaf conductance declined
and remained at about –1·25 MPa and 300
mmol/m2· s, respectively, in the treatments
in which a terminal water deficit was induced.
Application of BAP to flowers had no effect on plant-water relations. The
water deficit reduced the number of pods that reached maturity (mature pods)
when no BAP was applied and increased seed yield in pods that filled seeds.
Application of BAP increased the number of pods that reached maturity.
However, the additional pods that reached maturity produced unfilled seeds.
Seed yield and harvest index were reduced in the BAP treatments, mainly as a
result of a reduction in seed number. An increase in seed abortion during seed
filling probably caused the reduction in seed number. We conclude that the
reduction in seed number and pod filling resulted from a shortage of
assimilates to fill all the mature pods produced.
Effects of post-anthesis water stress on the yield and grain protein concentration of barley grown at two levels of nitrogen
Authors: Fathi G. , McDonald G. K. , Lance R. C. M.
Published: August 2004

The interaction between nitrogen (N) rate and post-anthesis moisture stress in
6 cultivars of barley (Clipper, Stirling, Weeah, Schooner, Chebec, and Skiff)
was examined. Plants were grown in a glasshouse at 2 rates of N under
well-watered conditions until 3 days after ear emergence, when the stress
treatment was started. Yield and grain protein concentration (GPC) responses
and changes in the dry matter and N content of the straw and grain in the main
stem and tillers were examined separately.
Nitrogen increased grain yield in all cultivars except Weeah, with Skiff and
Stirling being the most responsive. Post-anthesis stress did not reduce yields
at the low N rate but large reductions occurred at the high N rate in all
cultivars; the yields of Stirling, Chebec, and Skiff were most affected. At
the low N rate, stress did not significantly affect kernel weight and GPC, but
kernel weight declined and GPC increased at the high N rate. Compared with the
main stem, tillers produced smaller grain with a lower GPC. The responses to N
and water stress, and the different sensitivities of cultivars to stress, were
largely due to the effects of the treatments on the growth of the tillers. In
Stirling, Chebec, and Skiff, grain yield and kernel weight from the tillers
were greatly reduced by stress, whereas Clipper showed relatively little
effect of N and stress on yield and kernel weight. Net remobilisation of dry
matter was increased by stress but not by N treatment, and the amount
remobilised varied between genotypes. At the high N rate, post-anthesis stress
increased the N content per kernel and net remobilisation of N. Although
genotypes differed in the net amount of N remobilised and in the N harvest
index, there was little variation in GPC between cultivars.
The work demonstrated that reductions in yield and kernel weight and increases
in GPC from post-anthesis stress can be greater when plants are grown at a
high rate of N than when the supply of N is limited. The different responses
to stress and N among the 6 cultivars were associated, in part, with the
pattern of tiller development. However, there appeared to be differences in
the sensitivity of grain filling to stress independent of the responses in
tillering. While the net remobilisation of dry matter and N differed between
cultivars, the amounts did not appear to be related to differences in kernel
weight or GPC.
Defoliation frequency and the response by white clover to increasing phosphorus supply 2. Non-structural carbohydrate concentrations in plant parts
Authors: Singh D. K. , Sale P. W. G.
Published: August 2004

The concentrations of total non-structural carbohydrate (%TNC) and its
various forms (soluble sugars and starch) were measured in white clover plants
that were grown in a glasshouse with different levels of P supply (0, 30, 90,
and 180 mg/pot) and subjected to 3 defoliation frequencies (1, 2, and 4
defoliations over 36 days). Frequent defoliation reduced %TNC.
Increasing P supply to the clover plants had the opposite effect, but to a
lesser extent, and tended to reverse the decline in %TNC resulting from
frequent defoliation. Stolons were the plant parts where most of the
non-structural carbohydrate reserves were stored, with concentrations varying
from <2 to >11% TNC on a dry weight basis, according to the
treatment received. Minimal changes occurred in the %TNC for the leaves
or roots as a result of treatments. The fluctuations in non-structural
carbohydrate concentration in the stolons were mainly due to changes in the
starch concentration, since the stolon sugar concentration was relatively
constant between various treatments. A logistic curve closely defined the
relationship (r2 =
0·98) between the starch concentration in the stolons and dry matter
yield of leaves, suggesting that stolon starch reserves are a function of the
size of the leaf canopy. Canopy size, in turn, was dependent on the duration
of the regrowth period and, to a lesser extent, on the P supply. The maximum
starch concentration in the stolons was around 8% under the conditions
of this experiment.
Tunicamycin reduces wool growth by slowing the mitotic activity of wool follicles
Authors: Davies S. C. , Williams I. H. , White C. L. , Edwards J. E. Hocking
Published: August 2004

Reductions in wool growth have previously been observed in ewes exposed to low
levels of corynetoxins, the causal agents of annual ryegrass toxicity. In this
experiment, tunicamycin, a commercially available and closely related toxin,
was infused into an isolated area of skin on the abdominal flank. Eleven sheep
were continuously infused for 5 days with saline on one side and a total dose
of either 35 or 350 µg tunicamycin/kg affected skin on the other
side. Both fibre length (P < 0·05) and fibre
diameter (P < 0·01) were reduced by
tunicamycin treatment. Cell division in the wool follicle bulb was also
reduced by tunicamycin (P < 0·005), indicating
that the toxin is able to have a direct effect on the follicles and their
ability to produce wool. The permeability of the vascular system increased in
the skin tissue treated with tunicamycin, but only at the highest toxin dose
(P < 0·05); therefore, poor nutrient supply to
the follicle may be a minor contributor to reduced wool growth. The direct
effect of tunicamycin on the wool follicle explains why wool growth is reduced
by low levels of corynetoxins independently of, and prior to, effects on the
whole animal.
Evaluation of sugarcane morphological descriptors using variance component analysis
Authors: Gallacher D. J.
Published: August 2004

Genotypic, environmental, interaction, and error variances were studied for
each of 24 qualitative and 142 quantitative morphological characters. Data
were collected in 3 character sets: vegetative macromorphological,
inflorescence, and epidermal. Broad-sense heritability was estimated for
quantitative characters, and variance components were estimated. Non-zero
significance was determined for variance components of all characters. Many
characters were identified as having a large genetic component to their
variation. Optimising the descriptive power of vegetative macromorphology
characters requires the use of test clones to quantify the environmental
effect, and a high level of sampling to reduce error variance. Less work is
required for inflorescence characters, which are mostly highly heritable. Some
valuable epidermal characters were identified.
Black point of wheat: in vitro production of symptoms, enzymes involved, and association with Alternaria alternata
Authors: Williamson P. M.
Published: August 2004

Black point in wheat has commonly been thought to be caused by
Alternaria alternata. To obtain a method for screening
for resistance to this problem, the process by which
A. alternata infects wheat grain was observed in
resistant and susceptible varieties. No association was found between
infection with A. alternata and black point symptoms. A
technique was developed to produce symptoms in vitro
which showed the detection and location of the peroxidase enzymes involved.
Isoelectric focusing (IEF) determined considerable differences in peroxidase
isoenzyme activity from black point resistant and susceptible wheat varieties.
The potential exists for using IEF as a tool for rapid screening for black
point resistance.
A comparison of chickpeas and pasture legumes for sustaining yields and nitrogen status of subsequent wheat
Authors: Holford I. C. R. , Crocker G. J.
Published: August 2004

Six treatments were compared for their effects on wheat yields, nitrogen (N)
uptake, protein content, and fertiliser N requirements in a long-term rotation
study on a black earth and a red clay in northern New South Wales. Three of
the treatments were lucerne, subterranean clover, and snail medic, all grown
simultaneously from 1988 to 1990 and all followed by 3 years of wheat. The
other 3 treatments were biennial rotations of chickpea–wheat and
long-fallow–wheat as well as a continuous wheat monoculture, all lasting
6 years.
With the exception of the first wheat crop, which experienced very low
growing-season rainfall, lucerne was more beneficial than other legumes to
following wheat crops in terms of yield, protein content, and fertiliser N
requirement. Clover closely followed lucerne in the magnitude of its positive
effects, whereas medic and chickpea produced much smaller effects. Because of
the amount of N removed in the chickpea grain, it appeared that the small
positive effects of chickpea were due to soil N sparing or rapid
mineralisation from crop residues rather than any net contribution of N
fixation to soil N accretion.
Average yields of the 3 wheat crops following lucerne and clover were much
higher than average yields 20 years previously following lucerne, even though
average yields of continuously grown wheat have declined over the past 20
years. However, lucerne eliminated the need for N fertiliser for no more than
2 following wheat crops, and clover for only the first wheat crop. It appears
that the longer duration of lucerne benefits reported in earlier studies was
due to the higher background soil N levels as well as the lower yield
potential in the earlier years. Nevertheless, lucerne lowered the fertiliser
requirement of the third wheat crop by more than 50%. In contrast to
lucerne, annual legumes are probably most beneficial if grown in alternate
years with wheat.
The large benefits of long fallowing particularly on the black earth were
apparently caused by its enhancement of soil moisture and mineral N
accumulation. However, these N effects were surprisingly large considering the
degree of depletion of organic matter in long-fallowed soils.
Genetic variation for macro- and micro-nutrient concentration in perennial ryegrass (Lolium perenne L.)
Authors: Easton H. S. , Mackay A. D. , Lee J.
Published: August 2004

A perennial ryegrass breeding pool showed significant genetic variation for
concentrations in leaf of 8 of 16 macro- and micro-nutrients measured. Narrow
sense heritabilities (h2) ranged from 0 (B, Zn) to
0·9 (Mn, Na). Families selected for high and low herbage P
concentrations (h2 = 0·4) showed
consistent behaviour over a range of soil P treatments in a separate
experiment. Families similarly selected for herbage K concentrations
(h2 = 0·15) did not show such consistent
response in a later experiment. High soil K reduced herbage Mg concentrations,
but family means for herbage Mg and herbage K concentrations were not
correlated. The data show that selection for herbage content of Mg, Na, or P
is likely to be successful, but that herbage K is not simply regulated. These
results have implications for livestock Mg metabolism, for efficiency of P and
K use in mixed legume-based pastures, and for P and K wastage from pastures.
Triticale and barley for grain and for dual-purpose (forage+grain) in a Mediterranean-type environment. I. Growth analyses
Authors: Royo C. , Tribó F.
Published: August 2004

Field experiments were conducted for 2 growing seasons (1992 and 1993) at 2
sites in north-eastern Spain under irrigated conditions and high soil
fertility. Two 6-rowed barley varieties, 3 spring triticales, and 2 winter
triticales were evaluated for grain yield and for forage and grain production
in the same cropping season. Forage was cut when the first node was
detectable, and grain was harvested at ripening in both cut and uncut plots.
Barley, spring triticale, and winter triticale did not differ in biomass at
cutting. The number of tillers per plant at the beginning of jointing was
about 3·2 in both barley and winter triticale, and 0·7 in spring
triticale. Almost all of the biomass components at cutting were positively and
significantly correlated with forage yield.
Changes in dry matter accumulation and leaf area index and its components in
the uncut treatment fitted accurately to the same logistic curve. The maximum
number of living leaves per plant was reached between the beginning of
jointing and booting in barley and spring triticale, and around jointing in
winter triticale. The number of living tillers per plant at anthesis was
significantly higher in barley than in triticale. The number of spikes per
plant at anthesis was significantly lower in spring triticale than in barley
and winter triticale. The efficiency of the plant to accumulate dry matter was
greater in triticale than in barley.
In barley, grain filling in both cut and uncut harvesting treatments was
mainly dependent on current photosynthesis after anthesis. In triticale, which
was more affected by terminal abiotic stresses, both photosynthesis and
translocation of assimilates contributed to grain filling, independent of the
harvesting treatment.
Using fire to manage species composition in Heteropogon contortus (black speargrass) pastures. 1. Burning regimes
Authors: Orr D. M. , Paton C. J. , Lisle A. T.
Published: August 2004

A reduction in the proportion of the desirable grass
Heteropogon contortus(black speargrass) and an increase
in the undesirable Aristidaspp . (wiregrasses) are
evident in commercially grazed pastures. This paper evaluates the
effectiveness of spring burning regimes over a period of 4 years (1989-92) in
reversing this form of pasture degradation.
Burning increased the proportion of H.
contortus when pastures remained ungrazed but not when
pastures were grazed, because cattle selectively grazed
H. contortus after burning.
Burning reduced the proportion of Aristida spp and other
undesirable grasses such as Bothriochloa
decipiens and Chloris divaricata.
A strong ‘year of burning’ effect was evident.
Burning increased recruitment of H.
contortus which, in turn, increased plant density and
later basal area. Burning reduced the basal area of
Aristida spp initially by reducing tussock size and
later by reducing tussock numbers.
Results indicate that spring burning can restore pasture composition and that
burning in at least 2 successive years appears to be necessary. Light stocking
rates should be adopted so that the proportion of H.
contortuscan be maintained and so that pastures can be
burnt when and if required.
Intrinsic shear strength of leaves of pasture grasses and legumes
Authors: Henry D. A. , Simpson R. J. , Macmillan R. H.
Published: August 2004

The intrinsic shear strength of leaves of pasture grasses and legumes was
compared. Intrinsic shear strength is calculated as the force required to
shear a leaf, divided by the length of the cutting blade in contact with the
leaf material. Intrinsic shear strength was similar along a leaf blade of
Festuca arundinacea, but differed significantly for
different leaves on a plant. Different leaves on a plant of
Phalaris aquatica also differed significantly in
intrinsic shear strength. Leaves that had recently reached full expansion had
a higher intrinsic shear strength than leaves from lower on a tiller.
The leaves of different cultivars of P. aquatica
differed in their intrinsic shear strength. Their strength appeared to be
influenced by the stage of development of the plants and, in particular, by
the climatic conditions under which the leaves developed. The intrinsic shear
strength of grass leaves was 38–68 times that of legumes leaves, with a
1 · 8-fold difference between the species of grasses examined.
Significant variation in intrinsic shear strength exists between both species
of grasses and between species of grasses and legumes, indicating that there
is significant scope for the genetic improvement of pasture grasses. However,
it is unlikely that grasses could be improved to achieve the performance
levels of legumes.
Genetic variation between and within two populations of Trifolium glomeratum (cluster clover) in Western Australia
Authors: Bennett Sarita Jane
Published: August 2004

Genetic variation between and within populations of
Trifolium glomeratum (cluster clover) was studied using
seed collected from 2 sites in Western Australia: Mount Barker in the south
and Kwelkan in the wheatbelt. Seed was collected at 64 subplots within each
site and the material was grown at the University Field Station at Shenton
Park, Perth. Seventeen morphological characters were scored and the results
were analysed using analysis of variance, principal components analysis, and
cluster analysis. Within-site variation was much greater than had previously
been shown, and a considerable amount of between-site variation was present.
It is suggested that within-site variation is due to a small amount of
heterozygosity, as a result of limited outbreeding, being present in each
population. The 2 populations are shown to be distinct from each other, with
the population from Mount Barker containing more within-site variation. It is
suggested that this is a result of climatic stress influencing and reducing
the amount of variation being maintained in the Kwelkan population.