bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of the antisecretory action of prostaglandin D2in the rat colon
Authors: DIENER M. , NOBLES M. , SCHMITT C. , RUMMEL W. 
Published: December 2008

Previous studies have shown that prostaglandin D2(PGD2) inhibits neuronally mediated secretion in the rat colon. This antisecretory action of PGD2was further characterized by the use of a prostaglandin D receptor blocker. Prostaglandin D2inhibited the neuronally mediated short‐circuit current evoked by prostaglandin I2, which represents Cl‐secretion. The concentration‐response curve for the inhibition by PGD2was shifted to the right in the presence of the prostaglandin D receptor blocker, AH 6809. AH 6809 had no effect on the short‐circuit current response induced by prostaglandin E2or iloprost, a stable prostaglandin I2analogue, suggesting an interaction of the blocker with receptors specific for PGD2.A direct interaction of PGD2with enteric neurones was studied by determining its effect on acetylcholine release from enteric neurones preloaded with [3H]choline. Prostaglandin D2suppressed3H release induced by electric field stimulation. It had, however, no effect on the release induced by depolarization with potassium. The results suggest that the inhibitory action of PGD2on enteric cholinergic neurones is mediated by prostaglandin D receptors.
Cardiovascular and renal effects of intracerebroventricular angiotensin II in conscious sheep
Authors: HJELMQVIST H. , ULLMAN J. , HAMBERGER B. , RUNDGREN M. 
Published: December 2008

Effects on systemic and pulmonary haemodynamics, renal electrolyte excretion, and plasma concentration of vasopressin, catecholamines, electrolytes and proteins in response to intracerebroventricular infusions of [Val5]‐angiotensin II (ANG II) at 1, 2 and 4 pmol kg‐1min‐1in isotonic saline for 30 min were studied in conscious sheep (n = 6). Vehicle control infusions were performed in four of the animals. All three doses of ANG II were expected to increase CFS concentration of the peptide above physiological levels. All ANG II infusions were noticed to be dipsogenic, but the animals were not allowed to drink freely until at the end of the experiments (at 120 min post‐infusion).The systemic arterial blood pressure increased significantly only in response to 2 and 4 pmol kg‐1min‐1, concomitant with an increase of the systemic vascular resistance, whereas the cardiac output and heart rate remained unchanged. The central venous pressure increased only after administration of the highest ANG II dose, while pulmonary artery, and capillary wedge pressures were unaffected during all experiments.The plasma protein and K concentration fell in response to ANG II administration. Also here, the effects were significant only at 2 and 4 pmol kg‐1min‐1. The plasma levels of vasopressin, noradrenaline, adrenaline and dopamine did not change significantly in response to any of the infusions.The renal Na excretion increased by 100–400%, but not in a strictly dose‐dependent manner. Much smaller and more variable effects were seen on the renal K excretion.We conclude that: (1) supraphysiological CSF ANG II levels are needed to cause a pressor effect when the peptide is administered via the intracerebroventricular route in conscious sheep; (2) the blood pressure is increased exclusively via peripheral vasoconstriction and; (3) increased vasopressin release does not contribute to the cardiovascular changes. The results also demonstrate that ANG II may cause haemodilution via a central site of action.
Resetting of tubuloglomerular feedback by interrupting early distal flow
Authors: MORSING P. , VELAZQUEZ H. , ELLISON D. , WRIGHT F. S. 
Published: December 2008

Cell–cell contact between the macula densa and the glomerular arterioles is thought to provide the information pathway for the tubuloglomerular feedback (TGF) mechanism. When concentrations of sodium and chloride in the macula densa segment are increased, a signal is transmitted through the extraglomerular mesangium to contract the afferent arteriole. In addition, some observers have described a second region of contact between a later part of the distal tubule and the afferent arteriole of the same nephron. In this region the connecting tubule (CNT), and sometimes nerves that make contact with the cells of this CNT, were found. This arrangement gives another potential tubular segment, besides the macula densa plaque, in which the composition of tubular fluid may regulate glomerular dynamics.The present study was designed to investigate whether interrupting flow in the distal tubule downstream from the macula densa would influence the TGF mechanism. TGF was examined in rats by orthograde microperfusion, before and after blockade of the distal nephron with castor oil. Two variables were measured: maximum decrease in stop‐flow pressure (ΔPsf), and perfusion rate which elicits half‐maximal decrease in ΔPaf (V1/2). The fluid arriving at the blocking point was collected into a micro‐pipette. The results show a significant increase in V1/2 from 19 to 25 nl min‐1after 30 min of blockade. In conclusion the results support a role of the distal nephron in the control of the TGF mechanism.
Exogenous arachidonic acid inactivates protein kinase C in mouse pancreatic islets
Authors: THAMS P. , HEDESKOV C. J. , CAPITO K. 
Published: December 2008

The effect of arachidonic acid on protein kinase C activity and insulin secretion in mouse islets was investigated. Arachidonic acid stimulated protein kinase C activity in islet cytosol and membrane fractions by substituting for phosphatidylserine. Stimulation by arachidonic acid was dependent on either Ca2+ or the phorbol ester 12‐O‐tetradecanoylphorbol 13‐acetate, was potentiated by the combined addition of Ca2++ 12‐O‐tetradecanoylphorbol 13‐acetate, and did not further increase protein kinase C activity in the presence of saturating concentrations of phosphatidylserine. Arachidonic acid stimulation of protein kinase C was prevented by binding of arachidonic acid to albumin.In the absence of extracellular Ca2+, exogenous arachidonic acid stimulated insulin secretion. Arachidonic acid‐induced insulin secretion was not potentiated by 12‐O‐tetradecanoylphorbol 13‐acetate and was not prevented by the protein kinase C inhibitor staurosporine, suggesting that arachidonic acid‐induced insulin secretion may occur independently of protein kinase C activation. Arachidonic acid‐induced insulin secretion in Ca2+‐free medium was on the other hand potentiated by addition of extracellular Ca2+.Stimulation of insulin secretion by exogenous arachidonic acid was associated with inactivation of protein kinase C. Inactivation of protein kinase C was also observed in islet homogenate after pre‐incubation with arachidonic acid. Arachidonic acid‐induced protein kinase C inactivation in islet homogenate was prevented by albumin or MgATP. Inactivation by arachidonic acid in intact islets was, however, not produced during enzyme isolation and was not prevented by inclusion of albumin or MgATP during preparation of protein kinase C extracts.In conclusion, it is suggested, that arachidonic acid, by inactivating protein kinase C, may exert toxic effects in islets, and that arachidonic acid may stimulate insulin secretion by a non‐physiological mechanism, possibly involving an ionophoretic effect of arachidonic acid to induce Ca2+‐mediated insulin release.
Myocardial oxygen supply and lactate metabolism during marked arterial hypoxaemia
Authors: GRUBBSTRÖM J. , BERGLUND B. , KAIJSER L. 
Published: December 2008

Myocardial O2 delivery and changes in myocardial lactate metabolism during marked hypoxaemia (pao2 5‐5.4 kPa, Sa O2 70–75%) produced by 12% O2 breathing were studied in 12 healthy subjects at rest and during supine exercise up to maximal intensity. Blood for O2 and lactate analyses was sampled from catheters in an artery (a) and the coronary sinus (cs) and coronary sinus blood flow (CSBF) was measured by thermodilution. Lactate metabolism was evaluated in a subgroup of the subjects using i.v. infusion of [14C]lactate.At rest and during submaximal exercise up to heart rate 156 beats min‐1 myocardial O2 uptake (MQO2) was maintained at the same level during hypoxaemia as during normoxaemia. This was achieved at rest mainly by a more complete O2 extraction, during exercise entirely by greater CSBF. During maximal exercise CSBF was 35% greater during hypoxaemia than normoxaemia, while there was no difference in cs O2 saturation. Maximal MQO2 was smaller during hypoxaemia than normoxaemia in spite of no difference in rate pressure product. The a‐cs difference of lactate was reduced during hypoxaemia and there was a significant myocardial release of lactate, as calculated from [14C]lactate data, during hypoxaemic exercise, but not during hypoxaemic rest or normoxaemic rest and exercise. It is concluded that the heart has a coronary flow reserve of about 35%, which can be utilised under hypoxaemia. When this reserve is insufficient to supply the myocardium with oxygen lactate is produced to cover part of the myocardial ATP regeneration.
Effect of endothelium‐derived relaxing factor on renin secretion from isolated mouse renal juxtaglomerular cells
Authors: SCHRICKER K. , RITTHALER T. , KRÄMER B. K. , KURTZ A. 
Published: December 2008

This study aimed to examine the direct influence of native endothelium derived relaxing factor (EDRF) on renin secretion. To this end isolated mouse renal juxtaglomerular cells were cocultured with bovine aortic endothelial cells which produced and released significant amounts of EDRF as assayed by guanylate cyclase activities which were measured separately in endothelial and juxtaglomerular cells as well as in the cocultures of juxtaglomerular with endothelial cells. EDRF production was blunted in the absence of extracellular L‐arginine and in the presence of Nw‐nitro‐L‐arginine (L‐NAG; 200 μM).Inhibition of endothelial EDRF production by removal of arginine or addition of L‐NAG was associated with a significant decrease of renin secretion from the cocultures while the same regimen had no effect on renin secretion from JG cells alone. Exogeneous generation of nitric oxide by the addition of sodium nitroprusside (100 μM) stimulated renin secretion in the cocultures both at normal and inhibited EDRF formation as well as from juxtaglomerular cells alone.These findings suggest that native EDRF released from vascular endothelial cells is a stimulatory signal for renin secretion from renal juxtaglomerular cells.
Influences of stimulation frequency and temperature on interval‐force relationships in guinea‐pig papillary muscles
Authors: SPENCER C. I. , MÖRNER S. E. J. N. , NOBLE M. I. M. , SEED W. A. 
Published: December 2008

Spencer, C. I., Mörner, S. E. J. N., Noble, M. I. M. & Seed, W. A. 1994. Influences of stimulation frequency and temperature on interval‐force relationships in guinea‐pig papillary muscles. Acta Physiol Scand 150, 11–20. Received 12 January 1993, accepted 25 August 1993. ISSN 0001–6772. Departments of Medicine and Academic Unit of Cardiovascular Medicine, Charing Cross and Westminster Medical School, London, UK and Department of Pharmacology, University of Lund, Sweden.Relationships between contractile force and the preceding and pre‐preceding stimulation intervals were studied in papillary muscles by interposing variable test intervals during steady‐state pacing. The strength of test contractions increased exponentially to a maximum as the preceding (test) interval was lengthened. Contractility decreased as an exponential function of pre‐preceding interval. At 37 oC, the half times for these processes were unaffected by increasing the steady‐state frequency from 1 to 3 Hz. At 27 oC, the force increase with preceding interval was accelerated and the decay with pre‐preceding interval was retarded as the stimulation frequency was increased from 0.33 to 2 Hz.The timecourses of force increase and decay were similar to each other during stimulation at an optimum frequency characteristic for the temperature. Cooling from 37 to 27 oC prolonged the half times for force increase and decay by factors of 4.5 and 3 respectively. The slope of the linear relationship between the force of the contraction pre‐preceded by the test interval and the immediately subsequent contraction (recirculation fraction) was also halved.These results suggest that high stimulation frequency and low temperature uncouples cellular processes underlying the interval dependence of cardiac contractility. The temperature sensitivities are consistent with these processes being enzymatic. The reduced recirculation fraction provides a mechanism for the lowered threshold frequency for sustained mechanical alternans at 27 oC.
In vivo effects of endothelin‐2, endothelin‐3 and ETAreceptor blockade on arterial, venous and capillary functions in cat skeletal muscle
Authors: EKELUND U. 
Published: December 2008

Ekelund, U. 1994.In vivoeffects of endothelin‐2, endothelin‐3 and ETAreceptor blockade on arterial, venous and capillary functions in cat skeletal muscle.Acta Physiol Scand150, 47–56. Received 31 March 1993, accepted 25 May 1993. ISSN 0001–6772. Department of Physiology & Biophysics, University of Lund, Sweden.This study describes, in quantitative terms, the effects of endothelin‐2 and endothelin‐3 on vascular tone (resistance) in large‐bore arterial resistance vessels (> 25 /μm), small arterioles (< 25 μm) and the veins, as well as on capillary pressure and fluid exchange in cat gastrocnemius musclein vivo.Infusion of endothelin‐2 or endothelin‐3 (200–1600 ng kg‐1min‐1, i.a.) elicited an initial transient dilation, followed by a dose‐dependent, slowly developing constrictor response, being maintained after cessation of the infusion. At the dose of 400 ng kg‐1min‐1(n= 9), infused i.a. during 20 min, endothelin‐2 caused an average increase in total regional vascular resistance of 80%, and endothelin‐3 of 35%, and the site of constrictor action of both peptides was preferentially located to the small arterioles. Endothelin‐2 also constricted the veins and, hence, evoked a pronounced capacitance response, whereas endothelin‐3 was devoid of any venoconstrictor effect. This difference, via effects on the pre‐/post‐capillary resistance ratio, led to a more pronounced fall of capillary pressure in response to endothelin‐3 than to endothelin‐2. The new specific competitive ETAreceptor antagonist, FR 139317, abolished the vasoconstrictor response to both endothelin‐2 and endothelin‐3in vivo,whereas the preceding vasodilator responses were unaffected. These results, taken together with those of our previous analogous study of the effects of endothelin‐1, indicated that all three endothelins were approximately equally as effective in eliciting the transient dilator response in skeletal musclein vivo,whereas the order of vasoconstrictor activity was endothelin‐1 > endothelin‐2 > endothelin‐3. Due to an especially pronounced venoconstrictor activity of endothelin‐1, this peptide, in contrast to endothelin‐2 and ‐3, evoked a rise in capillary pressure, with a consequent net transcapillary fluid filtration and muscle tissue oedema formation. The results further indicated that the vasoconstrictor responses to all endothelins in skeletal muscle were mediated by the ETAreceptor, whereas the initial transient vasodilator responses seemed to be mediated by the ETBreceptor.
Renal sympathetic nerve activity during morphine abstinence in sino‐aortic baroreceptor‐denervated rats
Authors: DELLE M. , RICKSTEN S. ‐E. , THORÉN P. 
Published: December 2008

This study was undertaken to investigate the influence of the arterial baroreceptors on the response of renal sympathetic nerve activity (rSNA) during naloxone‐precipitated morphine abstinence in rats. In chronically baroreceptor‐denervated, morphine‐dependent rats, rSNA, mean arterial pressure (MAP) and heart rate (HR) were studied before and after repeated i.v. bolus doses of naloxone (0.005–5 mg kg‐1), during chloralose anaesthesia or in the conscious state.In the anaesthetized animals, naloxone doses of 0.05–5 mg kg‐1caused a pronounced inhibition of rSNA, reaching a level 61 % below pre‐naloxone activity. This was accompanied by increases in MAP and HR. In the conscious rats, the lower doses of naloxone elicired an initial state of increased somatomotor activity. This was paralleled by slight increases in rSNA and MAP. After 4–5 min, the behavioural excitation faded and was replaced by lethargy. The rats exhibited still signs of withdrawal in the form of piloerection, chromodacryorrhoea and defaecations. Concomitantly, rSNA returned towards the pre‐naloxone level, while MAP showed a sustained increase. The higher naloxone doses exacerbated the hypertension without any further changes in rSNA or in behaviour.We conclutle that the influence of the baroreceptors is of minor significance for the inhibition of rSNA during naloxone‐precipitated abstinence in anaesthetized rats. In conscious, intact rats, however, the baroreceptors seem to contribute to rSNA inhibition since no significance decrease of rSNA occurred in baroreceptor‐denervated rats in the present study. This is in contrast to our previous finding of a marked inhibition of rSNA in rats with intact baroreceptors.
Influence of herring (Clupea harengus) and herring fractions on metabolic status in rats fed a high energy diet
Authors: Lindqvist H. , Sandberg A.‐S. , Undeland I. , Stener‐Victorin E. , Larsson B. M. , Sannaveerappa T. , Lönn M. , Holmäng A. 
Published: December 2008

AbstractAim:  Few dietary studies have looked beyond fish oil to explain the beneficial metabolic effects of a fish‐containing diet. Our aim was to study whether addition of herring, or sub‐fractions of herring, could counteract negative metabolic effects known to be induced by a high‐fat, high‐sugar diet.Methods:  Rats were given six different diets: standard pellets; high energy diet with chicken mince (HiE control); high energy diet with herring mince (HiE herring); and high energy diet with chicken mince and either herring oil (HiE herring oil), herring press juice, PJ (HiE PJ) or herring low molecular weight PJ (HiE LMW‐PJ). Factors associated with the metabolic syndrome were measured.Results:  There were no differences in energy intake or body weight between the groups, but animals fed high energy diets had a higher body fat content compared with the pellet group, although not statistically significant in all groups. Mesenteric adipocyte size was smaller in the HiE herring oil group compared with the HiE control. Glucose clamp studies showed that, compared with the pellet group, the HiE control and HiE herring diets, but not the HiE herring oil diet, induced insulin resistance. Addition of herring or herring oil to the high energy diet decreased total cholesterol levels, triacylglycerols and the atherogenic index compared with the HiE control group.Conclusions:  The results suggest that addition of herring or herring oil counteracts negative effects on blood lipids induced by a high energy diet. The lipid component of herring thus seems to be responsible for these beneficial effects.
In Vitro Activities of Various Antifungal Drugs against
Aspergillus terreus
: Global Assessment Using the Methodology of the European Committee on Antimicrobial Susceptibility Testing
Authors: Lass-Flörl Cornelia , Alastruey-Izquierdo Ana , Cuenca-Estrella Manuel , Perkhofer Susanne , Rodriguez-Tudela Juan Luis 
Published: December 2008

ABSTRACT

This study presents in vitro susceptibility data for clinical (
n
= 48) and environmental (
n
= 31) isolates of
Aspergillus terreus
against nine antifungal agents. The methodology of the European Committee on Antimicrobial Susceptibility Testing was applied. Posaconazole and anidulafungin had the lowest and amphotericin B the highest MICs. No differences in susceptibility patterns were observed between environmental and clinical isolates.
Prevalence of Sulfonamide Resistance Genes in Bacterial Isolates from Manured Agricultural Soils and Pig Slurry in the United Kingdom
Authors: Byrne-Bailey K. G. , Gaze W. H. , Kay P. , Boxall A. B. A. , Hawkey P. M. , Wellington E. M. H. 
Published: December 2008

ABSTRACT

The prevalences of three sulfonamide resistance genes,
sul1
,
sul2
, and
sul3
and sulfachloropyridazine (SCP) resistance were determined in bacteria isolated from manured agricultural clay soils and slurry samples in the United Kingdom over a 2-year period. Slurry from tylosin-fed pigs amended with SCP and oxytetracycline was used for manuring. Isolates positive for
sul
genes were further screened for the presence of class 1 and 2 integrons. Phenotypic resistance to SCP was significantly higher in isolates from pig slurry and postapplication soil than in those from preapplication soil. Of 531 isolates, 23% carried
sul1
, 18%
sul2
, and 9%
sul3
only. Two percent of isolates contained all three
sul
genes. Class 1 and class 2 integrons were identified in 5% and 11.7%, respectively, of
sul
-positive isolates. In previous reports,
sul1
was linked to class 1 integrons, but in this study only 8% of
sul1
-positive isolates carried the
intI1
gene. Sulfonamide-resistant pathogens, including
Shigella flexneri
,
Aerococcus
spp., and
Acinetobacter baumannii
, were identified in slurry-amended soil and soil leachate, suggesting a potential environmental reservoir. Sulfonamide resistance in
Psychrobacter
,
Enterococcus
, and
Bacillus
spp. is reported for the first time, and this study also provides the first description of the genotypes
sul1
,
sul2
, and
sul3
outside the
Enterobacteriaceae
and in the soil environment.
Prevalence of Plasmid-Mediated Quinolone Resistance Determinants over a 9-Year Period
Authors: Kim Hong Bin , Park Chi Hye , Kim Chung Jong , Kim Eui-Chong , Jacoby George A. , Hooper David C. 
Published: December 2008

ABSTRACT

Recently, several plasmid-mediated quinolone resistance (PMQR) genes conferring low levels of quinolone resistance have been discovered. To evaluate the temporal change in the prevalence of PMQR genes over a decade in a tertiary hospital in the Republic of Korea, we selected every fifth isolate of
Escherichia coli
and
Klebsiella pneumoniae
and every third isolate of
Enterobacter cloacae
between 1998 and 2001 and between 2005 and 2006 from a collection of blood isolates. Six PMQR genes [
qnrA
,
qnrB
,
qnrC
,
qnrS
,
aac(6′)-Ib-cr
, and
qepA
] were screened by multiplex PCR and then confirmed by direct sequencing, and the
aac(6′)-Ib
-positive PCR products were digested with BtsCI to identify the
aac(6′)-Ib-cr
variant. Of 461 isolates, 37 (8%) had one of the six PMQR genes; 13 (5%) of 261
E. coli
strains, 13 (10%) of 135
K. pneumoniae
strains, and 11 (17%) of 65
E. cloacae
strains.
qnrB
was the most common PMQR gene and was found as early as 1998, whereas
qnrS
,
aac(6′)-Ib
-
cr
, and
qepA
emerged after 2000. None of the isolates carried
qnrA
or
qnrC
. Ciprofloxacin resistance increased over time (
P
< 0.001), and the overall prevalence of PMQR genes tended to increase (
P
= 0.20). PMQR-positive isolates had significantly higher ciprofloxacin resistance and multidrug resistance rates (
P
= 0.005 and
P
< 0.001, respectively). The increasing frequency of ciprofloxacin resistance in
Enterobacteriaceae
was associated with an increasing prevalence of PMQR genes, and this change involved an increase in the diversity of the PMQR genes and also an increase in the prevalence of the mutations in
gyrA
,
parC
, or both in PMQR-positive strains but not PMQR-negative strains.