bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature changes produced by the injection of catecholamines and 5‐hydroxytryptamine into the cerebral ventricles of the conscious mouse
Authors: Brittain R. T. , Handley S. L. 
Published: December 2014

1. Changes in temperature were determined following injection of noradrenaline, adrenaline, isoprenaline, dopamine and 5‐hydroxytryptamine (5‐HT) into the cerebral ventricles of the conscious mouse.2. Noradrenaline (1‐20 μg) and dopamine (10‐160 μg) caused falls in body temperature. Adrenaline (1‐20 μg) caused a slight and transient rise in body temperature followed by a fall. Isoprenaline (5‐20 μg) caused a rise in body temperature, hypothermia only occurring after very high doses (200 μg) of this catecholamine.3. α‐ and β‐adrenergic blocking agents, phentolamine (> 2 μg) and propranolol (> 5 μg) respectively, caused falls in body temperature when injected into the cerebral ventricles of the mouse.4. Specific drug antagonism studies were limited owing to the intrinsic effects of the α‐ and β‐adrenergic blocking agents. However, some evidence was obtained to indicate that noradrenaline mediated its effects through a central α‐type adrenergic receptor.5. 5‐HT (10‐160 μg) caused a fall in body temperature. The action of this indoleamine and the catecholamines in regard to thermoregulatory function is discussed.
5‐Hydroxytryptamine participation in the vagal inhibitory innervation of the stomach
Authors: Bülbring Edith , Gershon M. D. 
Published: December 2014

1. Intraluminal pressure was recorded from the isolated guinea‐pig and mouse stomach with the vagus and sympathetic nerves attached.2. The response to vagal stimulation, which consists of an excitatory and an inhibitory component, resembled the response to 5‐hydroxytryptamine (5‐HT), which has no direct action on the muscle but acts on intrinsic excitatory and inhibitory ganglia.3. In the presence of hyoscine, the effect of vagal stimulation, of nicotinic compounds and of 5‐HT were all purely relaxant. Competitive block of ganglionic receptors for acetylcholine reduced the vagal relaxation without antagonizing 5‐HT. Specific desensitization of ganglionic receptors for 5‐HT reduced the vagal relaxation without antagonizing nicotinic compounds.4. During the early phase of the blocking action of nicotine, responses to vagal stimulation and to 5‐HT were both abolished. As the non‐specific antagonism changed to the later phase of specific antagonism to acetylcholine, the inhibitory (but not the excitatory) component of the vagal response recovered partially, in parallel with the recovery of the relaxant effect of 5‐HT.5. The vagal inhibitory effect was completely abolished only when competitive block of acetylcholine receptors was combined with desensitization of 5‐HT receptors.6. Stimulation of the mouse stomach (after asphyxiation of the mucosa and exclusion of the luminal content) in the presence of hyoscine caused the release of 5‐HT; this release was blocked by tetrodotoxin.7. The results, together with previous observations that 5‐HT is contained within preganglionic nerve fibres in the myenteric plexus, are consistent with the hypothesis that 5‐HT, with acetylcholine, may be a neurotransmitter in the vagal inhibitory innervation of the stomach.
Properties of motor units in fast and slow skeletal muscles of the rat
Authors: Close R. 
Published: December 2014

1. Three kinds of motor unit have been distinguished in soleus (SOL) and extensor digitorum longus (EDL) muscles of adult rats on the basis of differences in isometric twitch contraction times measured at 35° C.2. SOL contains about thirty motor units of which about twenty‐seven are slow and three are intermediate with average contraction times of 38 and 18 msec respectively.3. EDL contains about forty fast motor units with an average contraction time of 11 msec.4. Average values for maximum isometric tetanic tension were 4·7 g for fast and slow units and 5·85 g for intermediate units.5. Average values for twitch‐tetanus ratios ranged from 0·2 to 0·227 for EDL muscles, SOL muscles and the three kinds of motor units.
The effect of stress on the concentration of 3β‐hydroxypregn‐5‐en‐20‐one (pregnenolone) and pregn‐4‐ene‐3,20‐dione (progesterone) in the adrenal gland of the rat
Authors: Holzbauer Margarethe , Newport Helen M. 
Published: December 2014

1. Pregnenolone and progesterone were estimated in extracts from adrenal glands of rats by gas—liquid chromatography.2. In unstressed rats their concentrations were found to be smaller than that of corticosterone.3. Acute stress caused an increase in the concentrations of these steroids which paralleled that of corticosterone.
Oxygen consumption by the isolated smooth muscle of guinea‐pig taenia coli
Authors: Bülbring Edith , Golenhofen K. 
Published: December 2014

1. An apparatus is described for simultaneous measurement of oxygen consumption and electrical and mechanical activity of isolated smooth muscle preparations.2. The mean oxygen uptake by the isolated taenia coli of the guinea‐pig was 10‐20 μl./g/min.3. In spontaneously active preparations, adrenaline (10−8‐10−7 g/ml.) caused, with the inhibition of electrical and mechanical activity, a reduction in oxygen uptake.4. After prolonged exposure to substrate free solution spontaneous activity ceased periodically. Adrenaline, when applied during a silent period, had no detectable effect on resting oxygen consumption, while readmission of substrate, either glucose or β‐hydroxybutyrate, increased oxygen uptake.5. Adrenaline did not modify the increased oxygen uptake during the initial recovery period when it was given simultaneously with the substrate. However, adrenaline shortened the time interval which elapsed from the addition of substrate until spontaneous activity was resumed, indicating an acceleration of the recovery process.
The relationship of the sphincter of Oddi to the stomach, duodenum and gall‐bladder
Authors: Wyatt A. P. 
Published: December 2014

Flow through the sphincter of Oddi was studied by a constant‐pressure perfusion apparatus, and by using a constant rate of infusion and measuring pressure changes just proximal to the sphincter. Pressure changes from balloons placed in the gastric antrum and duodenum were recorded. Despite considerable variation in activity and behaviour, the following conclusions were reached.1. The sphincter of Oddi appears to be partially autonomous but is readily affected by changes in duodenal tone.2. Reflex inhibition of the sphincter of Oddi is seen on electrical and mechanical stimulation of the gall‐bladder but not with passive pressure changes within the gall‐bladder.3. This reflex is relayed through the coeliac ganglion.4. There is a definite relationship between gastric antral activity and flow through the sphincter of Oddi. This is more obvious when food is present in the stomach.5. Mechanical or electrical stimulation of the stomach, duodenum, or upper small bowel influences the tone of the sphincter of Oddi.
Responses of skin blood vessels to bradykinin, histamine and 5‐hydroxytryptamine
Authors: Greaves Malcolm , Shuster Sam 
Published: December 2014

1. The responses of human cutaneous blood vessels to intradermal injection of bradykinin, histamine and 5‐hydroxytryptamine (serotonin) are studied in order to evaluate the ability of these agents to mediate the vascular changes of sustained acute inflammation in the skin.2. Bradykinin produces erythema, owing to a direct effect on blood vessels, and wealing. Dose—response studies indicate that bradykinin is more potent than serotonin or histamine in respect of wealing.3. The response to serotonin differs qualitatively as well as quantitatively according to dose. High doses cause wealing and erythema with the characteristics of an axon reflex flare, but low doses produce erythema by a local effect without wealing.4. Using the technique of arterial occlusion, the occurrence of tachyphylaxis in respect of wealing was demonstrated with histamine and serotonin, but not with bradykinin. This evidence suggests that of the three agents, only bradykinin can mediate increased vascular permeability in sustained acute inflammation.5. The specificity of tachyphylaxis and the failure of anti‐histamine to antagonize bradykinin wealing suggest that bradykinin and histamine act on separate blood vessel receptors.6. Corticosteroids do not inhibit wealing due to a wide range of doses of bradykinin. The anti‐inflammatory activity of corticosteroids may therefore be due to reduced formation of kinins.
Cortical actions on hypoglossal motoneurones in cats: a proposed role for a common internuncial cell
Authors: Porter R. 
Published: December 2014

1. Intracellular records were made of the synaptic potentials produced in hypoglossal motoneurones when electrical stimuli were applied to the cat's motor cortex.2. The depolarizing synaptic responses reached their maxima in steps similar to those produced in the same motoneurones by suprathreshold stimulation of the lingual nerve.3. Interneurones in or near the spinal trigeminal nucleus were caused to discharge by cortical shocks adequate to produce synaptic potentials in hypoglossal motoneurones. The latencies and patterns of repetitive responses in these interneurones were consistent with their possible role as internuncial cells in the motor pathway from cerebral cortex to hypoglossal motoneurones.4. Individual interneurones in or near the spinal trigeminal nucleus could be caused to discharge both by stimulation of the lingual nerve and by stimulation of the motor cortex. This convergence suggests a common function for the internuncial cell in reflexly and cortically induced excitation of hypoglossal motoneurones and would allow the internuncial cell to be a site for integration of spatially separated excitatory influences.
Co‐operative action of calcium ions in transmitter release at the neuromuscular junction
Authors: Dodge F. A. , Rahamimoff R. 
Published: December 2014

1. The quantitative dependence of transmitter release on external calcium concentration has been studied at the frog neuromuscular junction, using intracellular recording and taking the amplitude of the end‐plate potential (e.p.p.) as an index of the number of packets released.2. The relation between [Ca] and the e.p.p. is highly non‐linear. The initial part of this relation on double logarithmic co‐ordinates gives a straight line with a slope of nearly four (mean 3·78 ± 0·2
S.D. in 28 experiments). Addition of a constant amount of Mg reduces the e.p.p. without altering the slope of the log e.p.p./log Ca relation.3. The slope of this logarithmic relation diminishes as [Ca] is raised towards the normal level.4. The results are explained quantitatively on the hypothesis that Ca ions combine with a specific site X on the nerve terminal forming CaX, and that the number of packets of acetylcholine released is proportional to the fourth power of [CaX].5. The analysis suggests that a co‐operative action of about four calcium ions is necessary for the release of each quantal packet of transmitter by the nerve impulse.
An examination of certain factors which might, or do, affect the vascular response to oxytocin
Authors: Lloyd Sybil , Pickford Mary 
Published: December 2014

1. A number of different observations were made on anaesthetized rats and some dogs to try to discover why it is that oxytocin is a vasodilator in dioestrus and anoestrus, and develops constrictor properties in oestrus and following sympathectomy.2. In those circumstances in which oxytocin in small or moderate doses raises blood pressure in the rat, the pressor effect is eliminated if the hormone is given during an infusion of adrenaline. In this respect the rat is closely similar to the dog.3. It was confirmed in anaesthetized oestrous rats that intravenous eserine eliminated the pressor response to oxytocin, and it was found that prostigmine did not reduce or change it. Thus, it may be concluded that the effect of eserine depends on its central sympathetic stimulant action and not on a peripheral effect.4. Rats which had been acutely or chronically adrenalectomized responded normally to oxytocin and both eserine and adrenaline were able to reduce, though not wholly eliminate, the pressor type of response. These results indicate that neither the adrenal medulla nor the cortex is essential for the action of oxytocin, nor for a large part of the action of eserine and adrenaline.5. The plasma concentrations of sodium, potassium and calcium were studied in a number of conditions affecting the response to oxytocin, namely, dioestrus, oestrus, and after administration of oestrogens, progesterone, adrenaline, eserine, hexamethonium, and dihydroergotamine. The cation changes observed could not be correlated with the type of response to oxytocin. The only measure found to affect the response was raising the plasma Na concentration by the infusion of disodium hydrogen phosphate. This reduced the pressor effect of oxytocin seen in oestrous female rats and in oestrogen treated males. The pressor response returned before the plasma sodium had fallen to normal levels.6. The administration of the oxytocin analogue, tyrosine‐methyl2 oxytocin which has a high receptor affinity and a low intrinsic activity, prevented the pressor response to oxytocin of oestrous rats, and the vasodilator response in the hind limb vessels of normal dogs. It is concluded that there is probably a single receptor for oxytocin from which both the constrictor and dilator effects are initiated.7. Oxytocin exerted apparently normal effects on the systemic blood pressure of oestrous or dioestrous rats given the β‐blocking agents pronethalol or propranolol.8. The present results, like previous ones, indicate that adrenaline is the factor linking both the gonadal state and the peripheral sympathetic nervous system with the type of response to oxytocin.9. An incidental observation was that male and female rats show differences in their response to sympathetic blocking agents and to a raised plasma sodium concentration.
The effect of ouabain on the secretion of catecholamines and on the intracellular concentration of potassium
Authors: Banks P. 
Published: December 2014

1. Perfusion of bovine adrenal glands with 0.1 m
M ouabain is accompanied by a doubling of the spontaneous rate of release of catecholamines and by a 66% increase in the response to stimulation with carbamylcholine.2. Perfusion with ouabain (0.1 m
M) reduces the intracellular content of potassium from 106 to 63 m
M.3. The effect of ouabain on catecholamine secretion is dependent upon the presence of Ca2+ ions in contrast to the effect upon the potassium content which is not dependent upon the presence of calcium.4. Ouabain has no effect on the release of catecholamines from isolated chromaffin granules both in the presence and absence of Ca2+ ions.5. A possible relationship between the secretion of catecholamines and the concentration gradient of potassium across the cell membrane is discussed.
Effects of salt loading and haemodilution on the responses of perfused cat kidneys to angiotensin
Authors: Lockett Mary F. 
Published: December 2014

1. Effects of single intra‐arterial injections (0.1‐1.0 μg) of angiotensin II have been observed on cat kidneys perfused with heparinized blood from heart—lung circuits.2. Angiotensin II always caused an abrupt decrease in renal plasma flow (R.P.F.) which reached maximum in 1–2 min and lasted over‐all for only 3.5‐4.0 min. Glomerular filtration rate (G.F.R.) usually and filtration fraction (F.F.) always increased.3. Angiotensin II caused antidiuresis provided that the kidney had not been subjected either to salt loading or to haemodilution within the preceding 3 hr. These pretreatments converted the antidiuretic action of angiotensin into a diuresis.4. Angiotensin II raised the rate of Na excretion, the urinary concentration of Na and the urinary Na/K whether anti‐diuretic or diuretic.
Effects of changes in PO2 and PCO2 and pH on the total vascular resistance of perfused cat kidneys
Authors: Lockett Mary F. 
Published: December 2014

1. The effects of change in arterial PO2, PCO2 and pH on the total vascular resistance (RVR) of the perfused cat kidney have been separately measured and expressed as ± percentage deviations from control values.2. Control levels in arterial blood were pH 7.38, P−O2 160 mm Hg, in equilibrium with 5% CO2.3. Increase in PO2 alone, in excess of 220 mm Hg, raised RVR reversibly reading 108% control levels at a PO2 280 mm Hg (P = < 0.001).4. High levels of PO2 favoured the onset of ‘outflow block’, which was characterized by irreversible increase in RVR accompanied by rise in plasma filtration fraction (F.F.) and in the extraction ratio for p‐aminohippuric acid (PAH extraction).5. Reduction in PO2 to 80 mm Hg decreased RVR by 4% (P = < 0.001).6. RVR was not significantly affected by pH changes within the range 7.25‐7.45. Lowering arterial pH to 7.15 raised RVR by 4% (P = < 0.001) reversibly. Increase in arterial pH to 7.56 raised RVR by 6% (P = < 0.001) reversibly.7. Changes in arterial PCO2 produced large inverse reversible changes in RVR. Halving PCO2 raised RVR by 18%; doubling PCO2 decreased RVR by 25%.8. Changes in RVR caused by alteration of arterial pH or PCO2 were not accompanied by changes either in F.F. or in PAH extraction.
A Gas Turbine Dynamic Model for Simulation and Control
Authors: Perez-Blanco Horacio , Henricks Todd B. 
Published: December 2014

The useful life of gas turbines and the availability of power after start-up depend on their transient response. For this reason, several articles have been written on the dynamic simulation of gas turbine systems in electrical generation, cogeneration, and marine applications. The simulations typically rely on performance maps and time lags extracted from manufacturer’s specifications. This work was undertaken to increase the generality of turbine models over what can be obtained from performance maps. The paper describes a mathematical computer model developed to investigate the dynamic response of a simple single-shaft gas turbine system. The model uses design parameters normally incorporated in gas turbine design (e.g. load coefficient, flow coefficient, and deHaller Number) as well as compressor and turbine stage geometry and compressor and turbine material properties. A dynamic combustion chamber model is also incorporated. Other input parameters are included to enable the model to be adaptable to various system sizes and environments.
The model was formulated in a graphical interface, and the results of several trials are displayed. The influence of important parameters (e.g. fuel-air ratio, IGVs, load, efficiencies) on turbine response from a “cold” start and from steady-state is studied. To gain further insights into the response, a start-up procedure similar to that reported in the literature for an industrial gas turbine system is simulated. Because of the approach used, the computer model is easily adaptable to further improvements and combined simulation of turbines and control systems.
Combining Bayesian Belief Networks With Gas Path Analysis for Test Cell Diagnostics and Overhaul
Authors: Palmer Carl A. 
Published: December 2014

Engine overhaul shops need a reliable analytical methodology to pinpoint the cause(s) of engine test-cell under-performance to aid the overhaul decision-making process. Gas path analysis codes have been somewhat successful, but have not been entirely satisfactory. Previous works [Doel, 1994] have raised the idea that if other information could be integrated with the gas path analysis results, it may be possible to achieve better results.
This paper presents a diagnostic system developed for the CF6 family of engines. The system integrates test cell measurements and the gas path analysis program results with information regarding engine operational history, build-up workscope, and direct physical observations in a Bayesian belief network. The paper lays out the nature of the problem and the system requirements and design.
The system produces a diagnosis while following a cost-effective diagnostic process using value of information calculations. This is illustrated through sample cases.
Comparative Thermoeconomic Analysis Between Combined Cycle Units Derived From Existing Steam Power Plants and a New Combined Cycle Plant
Authors: Negri di Montenegro G. , Peretto A. , Mantino E. 
Published: December 2014

In this paper, a thermoeconomic analysis is carried out for two and three pressure level combined cycles derived from existing steam power plants. The considered steam power plants are among the most widespread in the Italian territory (70 MW, 160 MW, 320 MW power output).
First of all, the gas turbine plants that best match the steam power plants’ requirements are selected among existing units.
Subsequently, the thermodynamic analysis for the repowered plants is performed, taking into account the off-design working condition of some components such as, the steam turbines and the condenser.
Then, the economic evaluation for the repowered plants is carried out by determining the cost per kWh, the pay back period and the internal rate of return. The analysis permits the most economic choice to be made.
The thermoeconomic investigation was also performed for a new combined cycle power plant.
The study has revealed that the repowering of the three existing steam power plants in two or three pressure level combined cycle plants is more convenient than building a new combined cycle with higher efficiency.
It has also pointed out that the repowering of the 320 MW existing steam power plant in a three pressure level reheat combined cycle plant supplies the lowest cost per kWh among all the other repowered plants analyzed.
The revamping and environment effect on the above mentioned existing steam power plants was also investigated and it resulted that this solution has a cost per kWh that is much higher than that of the repowered steam plants and the new combined cycle.
The Effect of Inlet Boundary Layer Thickness on the Flow Within an Annular S-Shaped Duct
Authors: Sonoda Toyotaka , Arima Toshiyuki , Oana Mineyasu 
Published: December 2014

Experimental and numerical investigations were carried out to gain a better understanding of the flow characteristics within an annular S-shaped duct, including the effect of the inlet boundary layer (IBL) on the flow. A duct with six struts and the same geometry as that used to connect compressor spools on our experimental small two-spool turbofan engine was investigated. A curved downstream annular passage with a similar meridional flow path geometry to that of the centrifugal compressor has been fitted at the exit of S-shaped duct. Two types of the IBL (i.e. thin and thick IBL) were used.
Results showed that large differences of flow pattern were observed at the S-Shaped duct exit between two types of the IBL, though the value of “net” total pressure loss has not been remarkably changed. According to “overall” total pressure loss, which includes the IBL loss, the total pressure loss was greatly increased near the hub as compared to that for a thin one. For the thick IBL, a vortex pair related to the hub-side horseshoe vortex and the separated flow found at the strut trailing edge has been clearly captured in the form of the total pressure loss contours and secondary flow vectors, experimentally and numerically. The high-pressure loss regions on either side of the strut wake near the hub may act on a downstream compressor as a large inlet distortion, and strongly affect the downstream compressor performance. There is a much-distorted three-dimensional flow pattern at the exit of S-Shaped duct. This means that the aerodynamic sensitivity of S-Shaped duct to the IBL thickness is very high. Therefore, sufficient carefulness is needed to design not only downstream aerodynamic component (for example centrifugal impeller) but also upstream aerodynamic component (LPC OGV).