bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Small Increments in Plasma Calcium Concentration on the Responsiveness of Forearm Resistance Vessels to Verapamil in Normal Subjects
Authors: Robinson B. F. , Phillips R. J. W. 
Published: August 2015

1. The effect of a small increase in local plasma calcium concentration on the responsiveness of the forearm resistance vessels to verapamil has been examined in normal subjects, by using a plethysmographic method with infusion of calcium and other agents into the brachial artery.
2. Infusion of calcium at a rate which increased the concentration in forearm venous blood by about 0.5 mmol/l caused basal blood flow to fall by 19% and the dilator response to verapamil to fall by 35% (n = 8; P&lt;0.02).
3. When, after 46 min, the infusion of calcium was discontinued, the dilator response to verapamil increased to reach a level 53% higher than the initial control (n = 8; P&lt;0.02).
4. Infusion of calcium had no effect on the dilator response to sodium nitroprusside.
5. Infusion of noradrenaline at a rate which caused a greater reduction in basal flow than that induced by calcium had no effect on the response to verapamil.
6. It is concluded that the dilator response to verapamil, which is thought to reflect activity of the potential operated system for calcium entry, is selectively depressed by a small elevation of plasma calcium concentration, but subsequently becomes elevated. These findings point to an important role for calcium in the regulation of membrane function in the resistance vessels and support the view that altered calcium handling may contribute to the development of primary hypertension.
Effects of Acipimox, a Nicotinic Acid Derivative, on Lipolysis in Human Adipose Tissue and on Cholesterol Synthesis in Human Jejunal Mucosa
Authors: Stirling C. , McAleer M. , Reckless J. P. D. , Campbell R. R. , Mundy D. , Betteridge D. J. , Foster K. 
Published: August 2015

1. The mode of action of acipimox (5-methyl-pyrazine carboxylic acid 4-oxide), an hypotriglyceridaemic agent, was examined in human adipose tissue and intestinal mucosa.
2. The rates of release of fatty acids and glycerol from human adipose tissue were measured in vitro. The release of fatty acids and glycerol from adipose tissue maximally stimulated by isoprenaline (10−5 mol/l) fell by 40 and 25% respectively (P&lt;0.025 and P&lt;0.025) in the presence of acipimox (10−5 mol/l). In submaximally stimulated adipose tissue (isoprenaline 10−7 mol/l) acipimox (10−4 mol/l) fully inhibited release of fatty acids (P&lt;0.05) and glycerol (P&lt;0.025) to basal rates. In unstimulated adipose tissue acipimox (10−3 mol/l) reduced the rate of glycerol release (P&lt;0.05), but not the rate of fatty acid release.
3. Cholesterol synthesis in jejunal mucosa was measured in vitro by the incorporation of [2-14C]-acetate into sterols. Addition of cholesterol to the incubation reduced [2-14C]acetate incorporation into sterols from 8.7 ± 2.1 (mean ± standard error) to 3.7 ± 1.0 pmol h−1 mg−1 of tissue (P&lt;0.01). Acipimox at 10−4-10−2 mmol/l had no consistent effect on cholesterol synthesis.
4. Acipimox appears to exert its main hypolipidaemic effect by reducing lipolysis and free fatty acid flux to the liver, thereby reducing the precursor pool size of very low density lipoprotein (VLDL)-triglyceride and VLDL synthesis.
Frusemide-Sensitive Sodium and Potassium Transport by Human Leucocytes
Authors: Johnson Valerie E. , Hilton P. J. 
Published: August 2015

1. Frusemide-sensitive sodium and potassium transport by normal human leucocytes has been studied in vitro by both isotopic and net flux techniques.
2. In physiological media the leucocyte exhibits a frusemide-sensitive influx of sodium and potassium of equal magnitude compatible with a 1:1 co-transport system.
3. Cells exposed to zero external sodium and potassium (osmolality maintained with choline) demonstrated a frusemide-sensitive sodium and potassium efflux.
4. Frusemide-sensitive potassium influx was dependent on the presence of external sodium but frusemide-sensitive sodium influx persisted unchanged in the absence of external potassium.
5. Frusemide-sensitive potassium influx was dependent on external chloride but frusemide-sensitive sodium influx was chloride-independent.
6. These last two observations make it likely that the frusemide-sensitive pathway is capable of operating in modes other than sodium-potassium co-transport.
Cytoplasmic Free [Ca2+] is Increased in the Platelets of Spontaneously Hypertensive Rats and Essential Hypertensive Patients
Authors: Bruschi Giacomo , Bruschi Maria E. , Caroppo Maurizio , Orlandini Guido , Spaggiari Marco , Cavatorta Angelo 
Published: August 2015

1. The cytoplasmic free calcium concentration ([Ca2+]i) was assessed with the fluorescent dye Quin 2 in platelets and lymphocytes of spontaneously hypertensive rats (SHR), normotensive Wistar—Kyoto rats (WKY), essential hypertensive patients (EHP) and normotensive human control subjects (NCS).
2. [Ca2+]i was significantly higher in the platelets of 8- and 20-week-old SHR in comparison with WKY. However, no difference was evident after weaning. Changes of cellular calcium in hypertensive rats apparently evolved simultaneously with the development of high arterial pressure.
3. [Ca2+]i was significantly higher in platelets of EHP than in NCS.
4. In lymphocytes of SHR, [Ca2+]i was not different from WKY at 4 and 8 weeks, but was increased at 14 weeks and at older ages. In EHP, intralymphocytic [Ca2+] was only modestly higher than in controls. On the whole, the results suggest that control of cytoplasmic calcium in these blood cells is similarly affected in human and animal models of primary hypertension.
The effect of Airway Anaesthesia on the Control of Breathing and the Sensation of Breathlessness in Man
Authors: Winning A. J. , Hamilton R. D. , Shea S. A. , Knott C. , Guz A. 
Published: August 2015

1. The effect on ventilation of airway anaesthesia, produced by the inhalation of a 5% bupivacaine aerosol (aerodynamic mass median diameter = 4.77 μm), was studied in 12 normal subjects.
2. The dose and distribution of the aerosol were determined from lung scans after the addition to bupivacaine of 99mTc. Bupivacaine labelled in this way was deposited primarily in the central airways. The effectiveness and duration of airway anaesthesia were assessed by the absence of the cough reflex to the inhalation of three breaths of a 5% citric acid aerosol. Airway anaesthesia always lasted more than 20 min.
3. Resting ventilation was measured, by respiratory inductance plethysmography, before and after inhalation of saline and bupivacaine aerosols. The ventilatory response to maximal incremental exercise and, separately, to CO2 inhalation was studied after the inhalation of saline and bupivacaine aerosols. Breathlessness was quantified by using a visual analogue scale (VAS) during a study and by questioning on its completion.
4. At rest, airway anaesthesia had no effect on mean tidal volume (VT), inspiratory time (Ti), expiratory time (Te) or end-tidal Pco2, although the variability of tidal volume was increased. On exercise, slower deeper breathing was produced and breathlessness was reduced. The ventilatory response to CO2 was increased.
5. The results suggest that stretch receptors in the airways modulate the pattern of breathing in normal man when ventilation is stimulated by exercise; their activation may also be involved in the genesis of the associated breathlessness.
6. A hypothesis in terms of a differential airway/alveolar receptor block, is proposed to explain the exaggerated ventilatory response to CO2.
Comparative Study of Serum Amyloid A Protein and C-Reactive Protein in Disease
Authors: Maury C. P. J. 
Published: August 2015

1. On the basis of results from 3000 parallel measurements of serum amyloid A protein (SAA) and C-reactive protein (CRP) in various clinical and experimental conditions, the relationship between these proteins was examined and the question of whether measurements of SAA can provide clinically useful information beyond that from CRP assays was evaluated.
2. The concentrations of SAA and CRP showed a close relationship in a wide range of clinical conditions and the general clinical impact of an elevated SAA or CRP level is similar. SAA was, however, more sensitive than CRP in reflecting inflammatory activity, and in some conditions characterized by normal or only slightly elevated CRP concentrations, measurements of SAA concentrations could be used for monitoring disease activity and response to treatment.
3. Marked variation in the ratios of SAA to CRP concentration occurred in response to different stimuli (e.g. surgical trauma/immunological tissue injury), suggesting the existence of independent, disease-specific pathways of regulation for the serum concentrations of SAA and CRP.
Mechanism of increased plasma urea after diuretic therapy in uraemic patients
Authors: Canton Antonio Dal , Fuiano Giorgio , Conte Giuseppe , Terribile Maurizio , Sabbatini Massimo , Cianciaruso Bruno , Andreucci Vittorio E. 
Published: August 2015

1. To clarify why diuretic therapy raises plasma urea in patients with chronic renal failure, three groups of uraemic subjects were treated with frusemide for 6 days.
2. In group 1 (n = 9), frusemide significantly decreased body weight and increased average plasma urea from 18.7 mmol/l to 28.8 mmol/l (P&lt;0.001). this rise in plasma urea was secondary to reduced urea excretion, which occurred in spite of an increase in urea filtration.
3. In group 2 (n = 7), frusemide was associated with salt replacement, in order to prevent salt depletion; in these patients neither reduction in urea excretion nor increase in plasma urea occurred.
4. In group 3 (n = 10), the marked diuretic-induced fall in urea clearance was found to be independent of enhanced proximal tubular re-absorption (measured in water diuresis).
5. These results show that the rise in plasma urea is due to increased tubular reabsorption of urea, presumably in the distal part of the nephron, secondary to extracellular fluid (ECF) volume depletion.
Altered metabolism of low density lipoprotein in humans after prolonged incubation in plasma
Authors: Kostner G. M. , Krempler F. , Dieplinger H. , Zechner R. , Teubl I. , Sandhofer F. 
Published: August 2015

1. Lecithin: cholesterol acyltransferase (LCAT) in combination with exchange and transfer proteins is known to alter the composition of all plasma lipoprotein fractions.
2. Human plasma from healthy donors was incubated for 24 h at 37°C in the absence and at 4°C and at 37°C in the presence of the LCAT inhibitors sodium iodoacetate (5 mmol/l), and the low density lipoprotein fractions (LDL) were isolated.
3. LDL isolated from LCAT-active plasma (LDL-a) exhibited pronounced alterations in their surface material: the relative content of phospholipids and of free cholesterol was reduced and the content of tetramethylurea-soluble apolipoproteins was increased. LDL isolated from plasma incubated at 37°C with or without sodium iodoacetate showed significantly increased triglyceride concentrations.
4. The LDL fractions from LCAT-active and LCAT-inactive (LDL-i) incubates were iodinated with 125I and 131I respectively, and their metabolic behaviour was studied in humans.
5. LDL-a was cleared from circulation at a slower rate as compared with LDL-i (t1/2 = 3.17 ± 0.47 vs 2.88 ± 0.45 days). The apparent fractional catabolic rate of LDL-a, calculated according to a two-pool model, was reduced by 22.2 ± 3.1%. Comparing LDL-a with LDL isolated from LCAT-inactive plasma which had been incubated at 37°C, the changes in the metabolic variables were less pronounced.
6. It is concluded that physiological alterations of the chemical compositions, caused by LCAT and exchange/transfer proteins, influence the metabolism of LDL.
Is salt reabsorption in the human sweat duct subject to control?
Authors: Schwarz V. , Simpson I. M. Naomi 
Published: August 2015

1. There is a time lag between the beginning of sweat secretion and fully effective production of fluid of minimum salt content. It is suggested that changes in permeability to water or electrolytes have to be effected and may account for the time lag.
2. The composition of thermal and pilocarpine sweat indicates that pharmacological stimulation does not wholely reproduce the physiological mechanism: pilocarpine sweat contains more sodium and more cyclic AMP, irrespective of the secretory rate.
3. The sweat obtained from patients with cystic fibrosis has been compared with that from normal children: the concentrations of cyclic AMP and cyclic GMP are the same. Defective sodium reabsorption in the patients is therefore unlikely to be due to inadequate or excessive synthesis of these cyclic nucleotides.
Urinary kallikrein and systemic prostacyclin synthesis during sodium chloride infusion in normal man
Authors: Watson M. L. , Cumming A. D. , Lambie A. T. , Oates J. A. 
Published: August 2015

1. An intravenous infusion of 3 litres of sodium chloride solution (saline: 150 mmol/l) was given over 1 h to normal subjects.
2. During and immediately after the infusion, renal plasma flow increased in the majority of subjects, but the rise was not statistically significant. Significant increases in urine flow, sodium excretion, urinary kallikrein excretion and urinary excretion of dinor-6-keto prostaglandin (PG) F1α, a measure of systemic PGI2 synthesis, were noted. Plasma renin activity and plasma protein concentration were significantly lowered by the infusion.
3. At 2 h after the end of the infusion, although urine flow fell significantly, sodium excretion had not decreased. The reduction in plasma renin activity and plasma proteins persisted, and excretion of kallikrein and the PGI2 metabolite returned to control values.
4. Overall, urinary kallikrein excretion correlated significantly with urine flow and with sodium excretion. Peak kallikrein excretion occurred in the second 30 min of the infusion, and preceded maximal urine flow and sodium excretion.
5. The results suggest that increased systemic synthesis of PGI2 occurs in response to an acute infusion of sodium chloride, and may be an adaptive response of the vasculature to volume expansion. They support a role for the renal kallikrein-kinin system in the early diuretic and natriuretic response to saline infusion; the reduction in plasma renin activity and plasma protein concentration may be involved in both the early response and the persistent natriuresis 2 h after the infusion.
Renin-aldosterone system suppression during water immersion in renovascular hypertension
Authors: Coruzzi P. , Biggi A. , Musiari L. , Ravanetti C. , Novarini A. 
Published: August 2015

1. We studied renin-aldosterone system behaviour in five renovascular hypertensive patients during central hypervolaemia by water immersion to the neck.
2. Water immersion significantly suppressed the high peripheral renin levels of the patients despite an autonomic renin secretion from the stenotic kidney, a significant reduction of mean blood pressure and an increase in distal tubule sodium concentration.
3. The effect of immersion on plasma aldosterone appeared to be primarily mediated via suppression of plasma renin activity (PRA).
4. Our data suggest that: (a) the renin secretion is mainly modulated by cardiopulmonary receptors activity; (b) the neurogenic reflex control of plasma renin activity is very effective in renovascular hypertension.
Reflex vascular responses in the finger to contralateral thermal stimuli during the normal menstrual cycle: a hormonal basis to Raynaud's phenomenon?
Authors: Lafferty K. , Trafford J. C. De , Potter C. , Roberts V. C. , Cotton L. T. 
Published: August 2015

1. Raynaud's phenomenon is a condition which primarily affects women and it must be assumed that hormonal influences are responsible.
2. To further investigate this assumption the effect of cyclic sex hormone fluctuations on the digital vascular reactivity of ten normal young women was studied by the diagnostic techniques of thermal entrainment of finger blood flow and Doppler ultrasound mapping of the digital arteries.
3. In the immediate pre-ovulatory period the results obtained were comparable with those found in patients with established Raynaud's phenomenon, suggesting that oestrogen has an important modulating effect in vivo on reflex peripheral vasomotor responses to thermal stimuli.
4. ‘Primary’ Raynaud's phenomenon may represent an exaggerated response to oestrogen.
Modulation of postjunctional α-adrenergic responsiveness by local changes in temperature
Authors: Vanhoutte P. M. , Cooke J. P. , Lindblad L.-E. , Shepherd J. T. , Flavahan N. A. 
Published: August 2015

1. In canine cutaneous veins, local moderate warming (37°-41°C) augments the responsiveness to postjunctional α1-adrenergic stimulation but depresses that to postjunctional α2-adrenergic activation. Moderate cooling (37°-24°C) has the opposite effect.
2. The effects of warming and cooling on α1-adrenergic responses are buffered by a large receptor reserve, allowing for the predominance of alterations in α2-adrenergic responsiveness.
Effects of desipramine on stimulation-induced contractions of the vas deferens of rats pretreated either chronically with desipramine or acutely with idazoxan
Authors: Doxey J. C. , Roach A. G. , Samuel J. 
Published: August 2015

1. In the present studies the effects of desipramine on the functional sensitivity of the prejunctional α2-adrenoceptors of the vas deferens were studied in pithed rats; contractions of the tissue were evoked by electrical stimulation (6 Hz) of the spinal sympathetic outflow.
2. Twenty-four hours after a single dose of desipramine (10 mg/kg, intraperitoneally) the inhibitory dose-response curves to either UK 14 304 or desipramine itself did not differ significantly from those seen in control animals, whereas both were displaced significantly to the right after 15 days pretreatment with desipramine. Thus the functional responsiveness of the prejunctional α2-adrenoceptors of the vas deferens was reduced by chronic but not acute pretreatment with desipramine.
3. In acute studies desipramine (0.3-4.3 mg/kg, intravenously) inhibited electrically induced contractions of the vas deferens of pithed rats. In the presence of the selective α2-adrenoceptor antagonist idazoxan (1 mg/kg, intravenously) desipramine potentiated nerve stimulation.
4. Although idazoxan (10-1440 μg/kg, intravenously) itself potentiated electrically induced contractions of the vas deferens the potentiation observed was markedly less than that obtained in rats pretreated acutely with desipramine (0.3 mg/kg, intravenously).
5. Acute simultaneous blockade of both prejunctional α2-adrenoceptors and uptake into nerve terminals can produce maximal potentiation of the contraction of the vas deferens to sympathetic nerve stimulation.
6. Results are discussed in relation to the hypothesis that the combination of an uptake inhibitor and a prejunctional α2-adrenoceptor antagonist, by enhancing noradrenergic transmission, may provide an antidepressant therapy with rapid onset of action.
Effects of Small-Particle Aerosols of Local Anaesthetic on Dyspnoea in Patients with Respiratory Disease
Authors: Stark R. D. , O'neill P. A. , Russell N. J. W. , Heapy C. G. , Stretton T. B. 
Published: August 2015

1. This study was devised to test the hypothesis that dyspnoea could be mediated by unmyelinated vagal sensory nerve endings (type J receptors) situated at alveolar level in the lung.
2. A modified jet nebulizer was used to generate an aerosol of local anaesthetic in particles small enough to allow alveolar deposition. Lignocaine (2% and 5%) produced aerosols with an arithmetic mean diameter (+sd) of 1.5+0.3 and 1.2+0.6 μm respectively, the mass median diameters being 1.7 (geometric standard deviation = 1.2) and 2.5 (geometric standard deviation = 1.7) μm respectively.
3. In experimental animal models a vagally mediated tachypnoea may be induced acutely by pulmonary microembolism. This response is known to be mediated by unmyelinated pulmonary afferent nerves in the vagus. Local anaesthetic agents administered as small particles, but not as large particles, obtunded this response, which suggests that the aerosol was capable of penetration to alveolar level.
4. Upon this background, a clinical study was designed to compare the effects of lignocaine with placebo both given as small-particle aerosols. Six patients, including two with diffuse alveolar pathology and four with chronic airflow obstruction, were studied. Respiratory frequency was determined before and after the aerosol, and exercise tolerance and breathlessness were measured with a 6 min walking test and visual analogue scales.
5. After lignocaine there was no clinical evidence of anaesthesia of the upper airways but bronchoconstriction occurred. While no overall effect of lignocaine on dyspnoea was apparent, individual patients showed some evidence of benefit. Although other factors deserve consideration, the lack of a dramatic effect on dyspnoea suggests that dyspnoea in such patients is not mediated principally by J receptors.
Circulating Histamine and Neutrophil Chemotactic Activity During Allergen-Induced Asthma: The Effect of Inhaled Antihistamines and Anti-Allergic Compounds
Authors: Morgan D. J. R. , Moodley I. , Cundell D. R. , Sheinman B. D. , Smart W. , Davies R. J. 
Published: August 2015

1. Plasma histamine and serum neutrophil chemotactic activity (S-NCA) were measured in ten atopic asthmatic patients on four separate occasions after allergen bronchial provocation testing (BPT).
2. Single doses of inhaled sodium cromoglycate (SCG; 20 mg), clemastine (0.5 mg), ketotifen (0.5 mg) and isotonic saline (0.9% NaCl) placebo were administered 30 min before bronchial provocation testing in random order and double-blind.
3. The airflow obstruction after BPT was monitored by measurement of forced expiratory volume in 1s (FEV1). Plasma histamine was measured by the double-isotope radioenzymatic assay and S-NCA by a modified Boyden chamber technique.
4. A highly significant decrease in FEV1 after BPT occurred on the placebo pre-treatment visit (P &lt; 0.001). Prior administration of inhaled SCG, clemastine and ketotifen significantly reduced the decrease in airflow obstruction seen after BPT when compared with placebo treatment (P &lt; 0.01, P &lt; 0.02, P &lt; 0.05 respectively).
5. No significant alteration in plasma histamine was detected during allergen-induced airflow obstruction.
6. Levels of S-NCA were significantly higher 5, 10 and 15 min after BPT when compared with the pre-challenge level (P &lt; 0.01, P &lt; 0.01, P &lt; 0.001 respectively). These levels were not significantly decreased when airflow obstruction was inhibited by the prior inhalation of SCG, clemastine or ketotifen.
The Maximal Sniff in the Assessment of Diaphragm Function in Man
Authors: Miller Juliet M. , Moxham John , Green Malcolm 
Published: August 2015

1. We studied diaphragm function in a total of 64 normal subjects, who had no past or present respiratory or neuromuscular impairment.
2. We measured transdiaphragmatic pressure (Pdi) during maximal sniffs and compared these values with Pdi during maximal static inspiratory efforts (PImax.).
3. The range of Pdi during maximal sniffs (82-204 cm H2O) had better defined lower limits than Pdi during PImax. (16-164 cm H2O) and a higher mean value : mean + sd for maximal sniffs was 137 + 28 cm H2O and for PImax. was 90 + 37 cm H2O.
4. The reproducibility of sniff Pdi was assessed in eight randomly chosen subjects over 3 days: the mean coefficient of variation was 7.2%. By comparison the coefficient of variation of Pdi during PImax. was 13.0% in seven subjects.
5. The maximal sniff is a spontaneous manoeuvre, easily performed, repeatable without tiring, and reproducible. Its measurement provides a more reliable quantitative method for assessment of diaphragm strength, which has potential in clinical practice.