bluuebunny/crossref_metadata_2025_split huggingface dataset:
17β‐OESTRADIOL ENHANCES NITRIC OXIDE SYNTHASE ACTIVITY IN ENDOTHELIUM‐DENUDED RAT AORTA
Authors: Binko J. , Murphy TV , Majewski H. 
Published: June 2007

SUMMARY1. It has been suggested that oestrogen‐produced vasodilatation is due to induction of endothelial nitric oxide synthase (NOS), but there are many reports of direct effects on vascular smooth muscle. In the present study, these processes were investigated in rat aorta isolated from ovariectomized rats.2. Short‐term treatment (10min) with 17β‐oestradiol (10 μmol/L) produced a small attenuation of the phenylephrine (PE)‐induced constriction, which was unaffected by the nitric oxide synthase inhibitor l‐N 5(‐1‐iminoethyl)ornithine (NIO; 100μmol/L). Long‐term treatment (6h) with 17β‐oestradiol (10 μmol/L) did not affect acetylcholine‐mediated vasorelaxation in endothelium‐intact aortic rings, but did attenuate PE‐induced constriction. This attenuation was also observed in endotheliumdenuded preparations after 17β‐oestradiol (10 μmol/L for 6h) and was far greater than the acute effect of 17β‐oestradiol (10 μmol/L).3. The attenuation produced by 17β‐oestradiol (10 μmol/L for 6 h) was significantly inhibited by concomitant treatment with cycloheximide (1 μmol/L), suggesting that protein synthesis was involved. NIO (100 μmol/L) also attenuated the effect, which suggests that the anti‐constrictor effect of 17β‐oestradiol occurs through the increased production of nitric oxide (NO). 17β‐Oestradiol increased NO production, as assessed by the conversion of [3H]‐arginine to [3H]‐citrulline in rat aorta. These effects were prevented by cycloheximide and NIO. The anti‐constrictor effect of oestrogen was blocked by the oestrogen receptor antagonist ICI 182780 (100nmol/L).4. Western blotting using an antibody specific for inducible nitric oxide synthase (NOS) revealed that 17β‐oestradiol (10 μmol/L for 24 h) treatment induced the formation of inducible NOS protein in the aorta, an effect blocked by cycloheximide. The results indicate that 17β‐oestradiol can attenuate the vasoconstrictor effect of PE by a specific receptor‐mediated process that involves induction of inducible NOS.
PATTERNS OF CIRCADIAN BODY TEMPERATURE RHYTHMS IN AGED RATS
Authors: Satinoff Evelyn 
Published: June 2007

SUMMARY1. Old rats of the same chronological age are not homogeneous with respect to their circadian temperature rhythm (CTR). Some old rats maintain a robust CTR, comparable with that of young rats, while others have a weakened and unstable CTR. Often, in the latter group, the CTR becomes flat and disappears. In almost all old rats there is a clear decrease in the amplitude of the CTR.2. The present paper describes several methods that are useful for distinguishing between old rats in different categories. Three patterns can be distinguished: (i) good (there is a clear difference between the daily body temperature (Tb) means in the light and dark, relatively high density (power) at a period of 24 h, low hour‐to‐hour fluctuation in Tb within a given day (low intradaily variability; IV) and high day‐to‐day stability in Tb (high interdaily stability; IS)); (ii) unstable (there is a variable difference between daily Tb means in the light and dark, very low density at the 24 h period, moderate IV and low IS); and (iii) flat (there is little or no difference or variation in daily Tb means in the light and dark, low or insignificant density at 24 h, highest IV and lowest IS).3. The importance of these distinctions in old rats is two‐fold. First, differences at a behavioural level may reflect fundamental differences in the brain. Second, the degree of deficits in one system, for example in the CTR, may be correlated with deficits in other systems, such as sleep‐waking. The methods described in the present paper are useful for obtaining qualitative information on the progressive deterioration of the CTR as animals age.
Experimental Biology 1997 Symposium on Neurobiology of Thermoregulation: Role of Stress: THERMOREGULATORY CHANGES BY HYPOXIA: LESSONS FROM THE PARAMECIUM
Authors: Malvin Gary M. 
Published: June 2007

SUMMARY1. In organisms ranging from paramecia to mammals, hypoxia elicits a regulated decrease in body temperature (Tb). A decrease in Tb is an important adaptation to hypoxia primarily because it lowers metabolic rate when oxygen supply is limited, thus facilitating survival.2. Although this beneficial response is extremely widespread among taxa, little is known of the cellular mechanisms that mediate hypoxia‐induced decreases in Tb. This is due, in large part, to the extreme complexity of vertebrate thermoregulatory systems.3. The thermoregulatory system of the unicellular paramecium is much simpler than that of vertebrates, yet it responds similarly to hypoxia. Research has explored the functional importance of hypoxia‐induced decreases in Th. In addition, a number of possible mediators and signalling pathways in hypoxia‐induced reductions in Tb have been assessed.4. In Paramecium caudatum, hypoxia appears to exert its thermoregulatory effects by inhibiting oxidative phosphorylation. Decreases in intracellular [ATP] and pH may be important intermediate signals. In addition, an endogenous opioid system appears to help mediate hypoxia‐induced changes in thermoregulatory behaviour.
ANGIOTENSIN II‐ AND PHORBOL ESTER‐INDUCED STEROIDOGENESIS BY OVINE ADRENOCORTICAL CELLS: EFFECT OF SEX AND THE GONADAL STATUS OF THE DONOR ANIMAL
Authors: Canny BJ , O'Farrell KA , Clarke IJ , Tilbrook A J. 
Published: June 2007

SUMMARY1. Angiotensin II (Angll) is well recognized as a regulator of adrenal Cortisol production in the sheep in vivo, but studies to date have failed to reveal this action on cultured ovine adrenocortical cells. Similarly, phorbol myristate acetate (PMA), an activator of protein kinase C, also has little effect on Cortisol production from ovine adrenocortical cells in vitro. Previous studies have, however, only looked at the responses to single concentrations of Angll or PMA, but have led to the suggestion that important differences exist between adrenocortical cells of the sheep and other species.2. We have extended previous studies by examining Cortisol production by ovine adrenocortical cells over 3h in response to a broad range of concentrations of either Angll (10−10 to 10−6mol/L) or PMA (10−10 to 10−5mol/L). In addition, we have investigated the possible role of gonadal factors in regulating these responses by comparing cultures derived from intact and gonadectomized male and female sheep.3. Angiotensin II caused concentration‐dependent increases (P<0.05) in Cortisol production in all cultures, with Cortisol production in response to Angll being greater (P < 0.05) in cultures from intact male sheep than in the cultures from orchid‐ectomized males or intact females. Cortisol production in response to Angll was modest in all groups (two‐ to 2.6‐fold increases).4. Phorbol myristate acetate elicited a concentration‐dependent inhibition (P<0.01) of basal Cortisol production in adrenocortical cultures from all groups. Phorbol myristate acetate produced a greater inhibition (P<0.05) of Cortisol production in cultures from intact male sheep than either the orchidectomized males or intact females.5. These findings demonstrate that ovine adrenocortical cells are responsive in a concentration‐dependent fashion to Angll and PMA. In addition, sex and gonadal factors may play an important role in regulating the responsiveness of adrenocortical cells to these factors.
CLORICROMENE REDUCES INFARCT SIZE AND ALTERS POSTISCHAEMIC BLOOD FLOW DEFECTS IN DOG MYOCARDIUM
Authors: Groban Leanne , Zvara David A. , Deal Dwight D. , Vernon Jason C. , Flye Christopher W. , Ma Xin‐Liang , Vinten‐Johansen Jakob 
Published: June 2007

SUMMARY1. The aim of the present investigation was to evaluate the effect of cloricromene on myocardial infarct size, regional myocardial blood flow and neutrophil accumulation in a canine model of ischaemia‐reperfusion.2. Dogs were instrumented to measure blood pressure, left anterior descending (LAD) coronary flow (flow probe) and regional myocardial blood flow (coloured microspheres). Two groups were studied: (i) CLO (n= 8) received an infusion of cloricromene (15 μg/kg per min); and (ii) VEH (n= 8) received saline. Infusions began at the onset of ischaemia (60 min) and continued through reperfusion (180 min).3. Haemodynamic responses were not different between groups. Cloricromene reduced the area of necrosis expressed as a percentage of the area at risk from 35 ± 3% in the VEH group to 23 ± 4% in the CLO group (P<0.05). Regional myocardial blood flow in the ischaemic region was different between groups; VEH dogs showed an early reperfusion hyperaemia followed by a progressive reduction in flow, while CLO dogs exhibited a gradual increase in reflow in the absence of an early hyperaemie response (P<0.05). Left anterior descending flow was enhanced during the reperfusion period in the CLO group compared with VEH (P<0.05). Cloricromene reduced polymorphonuclear neutrophil (PMN) infiltration (myeloperoxidase activity) in all myocardial regions when compared with VEH (non‐ischaemic zone, 0.34 ± 0.54 vs 0.05 ± 0.01 IU/l00 mg; ischaemic zone, 2.03 ± 0.80 vs 0.24 ± 0.08 IU/100 mg; and necrotic zone, 0.56 ± 0.04 vs 3.59 ± 1.09 IU/100 mg for VEH vs CLO groups, respectively; P<0.01). In a separate in vitro preparation, cloricromene reduced adherence of platelet‐activating factor (PAF)‐stimulated PMN to canine coronary endothelium. Stimulation of PMN by 100 nmol/L PAF resulted in adherence of 176 ± 36 compared with 48 ± 12 cells/mm2 in PAF‐stimulated PMN treated with 100 p. mol cloricromene (P<0.001).4. These data indicate that cloricromene reduces myocardial infarct size in a canine model of ischaemia‐reperfusion injury.Postischaemic blood flow patterns are significantly different in cloricromene‐treated dogs. Cloricromene‐mediated reductions in infarct size, neutrophil accumulation and adherence may play a role in this effect.
EFFECTS OF FR139317 ON RENAL RESPONSES TO ACUTE NITRIC OXIDE BLOCKADE IN ANAESTHETIZED RATS
Authors: Matsumura Yasuo , Kuro Toshihiko , Hashimoto Norio , Taira Shima 
Published: June 2007

SUMMARY1. Effects of FR139317, an endothelin ETA receptor antagonist, on renal haemodynamic and excretory responses to acute nitric oxide (NO) blockade were examined using anaesthetized rats.2. Intrarenal arterial infusion of NG‐nitro‐l‐arginine (NOARG), the NO synthase inhibitor, at a rate of 40 μg/kg per min, produced a significant decrease in renal blood flow, with no change in systemic blood pressure. There were significant decreases in urine flow and urinary excretion of sodium during infusion of NOARG. In animals pretreated with FR139317, similar renal responses to the NOARG infusion were observed.3. These results suggest that an action of endothelin‐1 via ETA receptors does not greatly contribute to the renal haemodynamic and excretory responses to acute blockade of renal NO production.
VENTRAL MEDULLARY CHEMORECEPTOR INPUTS TO NEURONS WITHIN THE NUCLEUS AMBIGUUS
Authors: Lewis DI 
Published: June 2007

SUMMARY1. The neural mechanisms by which neurons within the nucleus ambiguus respond to chemoreceptor stimuli applied to the ventral medullary surface (VMS) were investigated by determining the effect of low pH on the membrane potential and synaptic activity of these neurons in vitro.2. Small reductions in pH evoked an indirect membrane depolarization and/or an increase in excitatory synaptic activity in the majority of neurons. A direct membrane hyperpolarization was observed in the remaining neurons.3. Acetylcholine evoked a direct nicotinic receptor‐mediated membrane depolarization in these neurons. In addition, 37% of neurons received muscarinic synaptic input that originated from neurons located near the VMS.4. Low‐pH artificial cerebrospinal fluid (aCSF) potentiated the cholinergic component of the excitatory post‐synaptic potential (EPSP) evoked from near the VMS. Both this EPSP and the spontaneous EPSP evoked by low‐pH aCSF could be blocked by atropine.5. It is concluded that at least two different mechanisms exist to transmit chemoreceptive information from the VMS to neurons within the nucleus ambiguus. In the majority of neurons, an indirect excitatory response is observed that is due, in part, to activation of a polysynaptic cholinergic pathway originating near the VMS. In the remaining neurons, low pH evokes a hyperpolarization that is due to a direct action of the dendrites of the neurons themselves that project near to the VMS.
REGIONAL BRAIN ACTIVATION IN HUMANS DURING RESPIRATORY AND BLOOD PRESSURE CHALLENGES
Authors: Harper Ronald M. , Gozal David , Bandler Richard , Spriggs David , Lee Jason , Alger Jeffry 
Published: June 2007

SUMMARY1. The aim of the present study was to determine the brain sites mediating aspects of respiratory and cardiovascular control in adult humans using non‐invasive functional magnetic resonance (/MRI) procedures, thereby avoiding the spatial and temporal sampling limitations associated with classic neural assessment techniques.2. We examined activity changes across the entire brain following application of respiratory loads and upon induction of blood pressure and heart rate alterations. Magnetic resonance signals were visualized with a 1.5Tesla scanner in healthy volunteers (22‐52 years of age) using procedures that optimally assess changes in brain tissue microcirculation. Images were collected during a Valsalva manoeuvre, inspiratory loading, hypercapnia, cold pressor challenges to the hand and forehead and during intervening baseline states.3. Image values from experimental conditions were compared with corresponding baseline values on a pixel‐by‐pixel basis to identify brain regions in which the experimental conditions produced physiological activation.4. Ventilatory and pressor challenges elicited significant changes in regional image signal intensity in areas within the orbital cortex, amygdala, hypothalamus and hippocampus. Cerebellar, medullary and pontine areas were also recruited. However, while particular brain regions were only activated during specific stimuli, other regional signal changes occurred with multiple experimental manipulations.5. The findings indicate that respiratory and cardiac challenges elicit discrete activity changes over multiple brain sites. Activated regions include structures not often related to respiratory or cardiovascular regulation, such as the cerebellum; a prominent role for limbic forebrain structures in mediating the response is also suggested. The f MRI visualization procedures may greatly assist in the determination of neural structures that mediate respiratory and cardiovascular control in humans.
INTERFERON‐INDUCER POLYRIBOINOSINIC‐ POLYRIBOCYTIDYLIC ACID: A POTENT ANTI‐GASTRIC ULCER AGENT AND INHIBITOR OF THE GASTRIC PROTON PUMP IN RATS
Authors: Nath C. , Rastogi L. , Dikshit M. , Patnaik GK , Saxena RC , Gupta MB 
Published: June 2007

SUMMARY1. Polyriboinosinic‐polyribocytidylic acid (Poly I:Poly C), an interferon inducer was studied for its effect on gastric ulceration in rats. Polyriboinosinic‐polyribocytidylic acid (1,2 and 4 mg/kg, i.m.) showed a dose‐dependent inhibition of gastric ulcers induced by aspirin, cold restraint stress and pylorus ligation (Shay's model). Protective dose (PD50)±SEM values of Poly I:Poly C on these models of ulcers were 1.9±0.2, 2.3±0.4 and 2.8±0.4 (mg/kg, i.m.) respectively.2. Polyriboinosinic‐polyribocytidylic acid (10‐60 μg) produced dose‐dependent inhibition of gastric proton pump (H+/K+‐ATPase) activity in the gastric parietal microsomal fraction. The concentration of Poly I:Poly C causing a 50% inhibition (IC50)±SEM was found to be 17.6±1.2 μg.3. Polyriboinosinic‐polyribocytidylic acid caused a significant decrease in free and total acid and pepsin and an increase in mucin content in Shay (pylorus‐ligated) rat.4. Polyriboinosinic‐polyribocytidylic acid did not exert a significant influence on isolated tissue preparations for anticholinergic (acetylcholine‐induced contraction of guinea‐pig ileum) and H2‐anti‐histaminic (histamine‐induced contraction of rat uterus and guinea‐pig auricle) activities.5. Thus, the present study indicates that Poly I:Poly C may possess anti‐gastric ulcer activity as a result of inhibition of the gastric proton pump.
ASCITES FLUID OF NEPHROTIC RATS: SODIUM DODECYL SULPHATE‐POLYACRYLAMIDE GEL ELECTROPHORESIS PROTEIN PATTERN AND THE RENIN‐ANGIOTENSIN SYSTEM
Authors: Cruz C. , Correa‐Rotter R. , Mézquita C. , Medina‐Campos ON , Pedraza‐Chaverri J. 
Published: June 2007

SUMMARY1. The concentration of renin and angiotensinogen (Ao) and the activity of angiotensin I‐con verting enzyme (ACE) was measured in the ascites fluid of nephrotic rats obtained 8 days after puromycin aminonucleoside (PAN) injection.2. Ascites fluid, serum and urine proteins of these rats were analysed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE).3. Renin, Ao and ACE were found in the ascites fluid and the percentage of the ratio ascites fluid/(plasma or serum) ranged from 5.9 to 9.9%. The electrophoretic analysis revealed that the ascites fluid contained low (Mr < 66 kDa) and high (Mr < 66 kDa) molecular weight proteins. Albumin and six proteins higher than 66 kDa were present both in the ascites fluid and in serum from nephrotic rats.4. Data from the study suggest that some proteins in the ascites fluid, including renin, Ao and ACE, come from the plasma. It is possible that the loss of renin, Ao and ACE to the ascites fluid may be playing a role in the metabolic alterations of these three proteins in PAN‐nephrotic rats.
ANTI‐PROLIFERATIVE EFFECTS OF UNMODIFIED ANTISENSE OLIGODEOXYNUCLEOTIDES TARGETED AGAINST c‐raf mRNA: USE OF POLY (LYSINE/SERINE) COPOLYMERS OR CATIONIC LIPOPOLYAMINES
Authors: Aoki Y. , Kawa S. , Karasawa Y. , Horiuchi A. , Kiyosawa K. 
Published: June 2007

SUMMARY1. It is now known that nuclease‐resistant phosphorothioate antisense oligodeoxynucleotides (ODN) have some actions that are unrelated to antisense mechanisms. In the present study we assessed the anti‐proliferative effects of phosphorothioate (PS) and phosphodiester (PO; unmodified) antisense ODN targeted against c‐raf mRNA on pancreatic cancer cells in vitro, using poly (lysine/serine) copolymers conjugated with polyethylene glycol (PLSP) or cationic lipopolyamines (Transfectam) as carriers.2. The anti‐proliferative effect of the PO antisense ODN was significantly (P < 0.05) greater than that of the PS ODN, either complexed with PLSP (2 μmol/L ODN) or the Transfectam (0.5 μmol/L ODN). However, the effect of the PS or PO antisense ODN was not dependent on the antisense sequence. The c‐raf mRNA levels, assessed by reverse transcription‐polymerase chain reaction, were obviously reduced by both PO and PS anti‐sense ODN compared with mismatched ODN when complexed with the Transfectam (1 μmol/L ODN).3. Although the anti‐proliferative effects were mainly unrelated to antisense mechanisms, unmodified antisense ODN complexed with some carriers could be used as anti‐tumour agents considering that synthetic carriers can be modified to improve functions, such as delivery.
AUTACOID INTERACTIONS IN THE REGULATION OF BLOOD FLOW IN THE HUMAN PLACENTA
Authors: Gude NM , King RG , Brennecke SP 
Published: June 2007

SUMMARY1. Interactions between autacoids may play important roles in the regulation of blood flow in the foetal placenta. In order to investigate this aspect of placental haemodynamics, human normal‐term placentae were perfused in vitro and the responses of the foetal vessels to various combinations of vasoactive agents were determined.2. Vasoconstriction responses to 5‐hydroxytryptamine (5‐HT) were potentiated in the presence of endothelin‐1 (ET‐1), the thromboxane A2‐mimetic U46619 and a nitric oxide synthase inhibitor, N‐nitro‐l‐arginine (NOLA), but not in the presence of angiotensin II.3. N‐Nitro‐l‐arginine caused vasoconstriction of the perfused placenta and indomethacin attenuated this effect and blocked the potentiation of the 5‐HT response by NOLA.4. Indomethacin did not affect ET‐1‐induced pressure increases and infusion of U46619 had no effect on release of ET‐Iike immunoreactivity into the foetal placental circulation.5. The present study provides evidence of interactions between several autacoids in human perfused placentae in vitro. These interactions may play important roles in foetal placental haemodynamics in normal or pathological situations.
UREA: DIVERSE FUNCTIONS OF A ‘WASTE” PRODUCT
Authors: Withers Philip C. 
Published: June 2007

SUMMARY1. The urea cycle is essentially the simultaneous operation of two linear pathways, both primitive and widespread among animals; one is for arginine synthesis and the other is for arginine degradation to ornithine and urea.2. All animals may have the genetic capacity to express a urea cycle and many diverse groups of animals, from flatworms to mammals, have a functional urea cycle.3. Evolutionary changes in vertebrates of carbamyl‐phosphate synthetase (CPS) are directed from glutamine‐dependent (CPSIII) towards NH3‐dependent (CPSI) ureagenesis. Invertebrates, cartilagenous fish and the coelacanth have CPSIII (i.e. glutamine‐dependent), whereas lungfish, amphibians and amniote vertebrates have CPSI; the teleost Heteropneustes has CPSI‐like activity. That the coelacanth has CPSIII and Heteropneustes has ‘CPSI’ suggests that the form of CPS may by physiologically related (CPSIII in a balancing solute role and CPSI in a terrestrial, air‐breathing excretion role) rather than being phylogenetically constrained.4. Urea is a major balancing osmolyte in marine cartilagenous fish, the coelacanth and a few amphibians and some aestivating terrestrial amphibians. It is a storage osmolyte in cocoon‐forming aestivating lungfish and amphibians.5. Urea contributes towards positive buoyancy in marine cartilagenous fish.6. Urea functions for non‐toxic N transport in ruminant and pseudoruminant mammals7. Urea is a major solute in the mammalian (but not avian) kidney, contributing to a renal medullary osmotic gradient; it is substantially reabsorbed by mammalian nephrons.8. Urea is used as a preferred nitrogenous waste compared with ammonia at high ambient pNH3 or pH, with water restriction, or air breathing.9. Urea synthesis maintains acid‐base balance by the 1:1 stoichiometry of removal of HCO3− and NH4+.
ARE EXTANT LUNGFISH NEOTENIC?2
Authors: Joss Jean MP 
Published: June 2007

SUMMARY1. The thyroid axis in developing lungfish is being explored to ascertain whether it shows similar deficiencies to those characteristic of neoteny in urodele amphibians.2. At hatching, the pituitary of Neoceratodus forsteri comprises a lumen surrounded by a single layer of epithelial cells lying immediately below the hypothalamus, but unconnected to it. Over the first year of development, the number of pituitary cells increases and several cell types, including thyrotropes, can be recognized immunocytochemically, but the pituitary remains unconnected to the hypothalamus.3. By treating the lungfish with thyroid inhibitor, no increase in thyroid uptake of iodine, indicative of induced pituitary thyroid‐stimulating hormone (TSH) activity, could be demonstrated; neither was there any response to exogenous human TSH. In the liver, thyroid hormone receptors were found to be primarily of the a type.4. Taken together, these findings suggest that up to 1 year of age, lungfish development is equivalent to amphibian premeta‐morphosis, which is consistent with neoteny but cannot be taken as evidence for neoteny unless confirmed at later stages of lungfish life history, which are yet to be studied.