bluuebunny/crossref_metadata_2025_split huggingface dataset:
The cold face test (diving reflex) in clinical autonomic assessment: methodological considerations and repeatability of responses
Authors: Heath Martha E. , Downey John A. 
Published: August 2015

1. Cold stimulus applied to the face causes bradycardia and peripheral vasoconstriction (i.e. the diving reflex), and has been suggested as a test of the autonomic pathways involved. The purpose of this study was to define standard procedures for conducting the test and analysing the responses to the cold face test, to evaluate variability in responses between subjects and within subjects when the same test is repeated, and to examine its usefulness in clinical autonomic assessment.
2. Sixteen (nine female, seven male) healthy adult (21–35 years old) subjects were used. Cold stimulus was applied with gel-filled compresses. Forehead temperature under the compress as an indication of stimulus magnitude, heap rate, blood flow in the finger, toe and calf by venous occlusion plethysmography, and systolic and diastolic blood pressure were monitored. Three protocols were carried out in which the temperature (0, 5, 10, 15°C), placement (whole face, unilateral, forehead) and duration (20, 40, 60, 120 s) of the cold compress application were varied.
3. The data indicate that 0°C compresses applied bilaterally for 40 s produced the maximum bradycardia and peripheral vasoconstriction. No subject found this test to be obnoxious, but a 120 s application was objectionable to some subjects. This cold face test resulted in 22%, 72%, 59% and 44% reductions in heart rate and blood flow to the finger, toe and calf, respectively. There was significant between-subject variability, but good consistency in responses to tests repeated in the same subject on different days, at different times of day and in different seasons.
4. Two advantages of the cold face test are: (a) it can assess sympathetic-vascular smooth muscle pathways as well as the cardiac-vagal pathway; and (b) because its afferents are independent of the stretch and pressure receptors that are stimulated in other vagal–cardiac tests (Valsalva manoeuvre and respiratory sinus arrhythmia), it can help differentiate between abnormal vagal–cardiac and abnormal transducer–afferent pathway function.
Cation transport across lymphocyte plasma membranes in euthyroid and thyrotoxic men with and without hypokalaemic periodic paralysis
Authors: Oh Vernon M. S. , Taylor Elizabeth A. , Yeo Soo-Hwa , Lee Kok-Onn 
Published: August 2015

1. To study potassium transport in hypokalaemic periodic paralysis in a model of striated muscle cells, we measured specific [3H]ouabain binding (the number of sodium-potassium pumps), sodium-potassium-pump-mediated (ouabain-sensitive) 86Rb+ influx and sodium-potassium-pump-independent (ouabain-resistant) 86Rb+ influx in lymphocytes in vitro.
2. The subjects comprised euthyroid and thyrotoxic men with hypokalaemic periodic paralysis between attacks, men with uncomplicated thyrotoxicosis, and healthy men matched for age and weight.
3. Thyrotoxic patients, both with and without periodic paralysis, had significantly more lymphocyte sodium-potassium pumps than normal, and a significantly greater sodium-potassium-pump-mediated 86Rb+ influx. Antithyroid treatment corrected this defect in patients with thyrotoxic periodic paralysis. Euthyroid patients with cryptogenic periodic paralysis had significantly increased sodium-potassium-pump-mediated 86Rb+ influx, but a normal number of sodium-potassium pumps.
4. Only untreated thyrotoxic and euthyroid patients with periodic paralysis showed a significant increase in sodium-potassium-pump-independent 86Rb+ influx (5.2 ± 2.8 and 4.5 ± 1.8 respectively, vs control 2.8 ± 1.0 pmol h−1 10−6 cells; mean ± sd; P &lt; 0.001, P &lt; 0.005).
5. We conclude that thyrotoxicosis increases the number and activity of sodium-potassium pumps and facilitates, but is probably not necessary for, periodic paralysis. Hypokalaemic periodic paralysis is associated with an increase in sodium-potassium-pump-independent potassium influx.
Calcium-entry blockers during porcine cardiopulmonary resuscitation
Authors: von Planta Martin , Weil Max Harry , Gazmuri Raul J. , Ritz Marc A. , Rackow Eric C. 
Published: August 2015

1. Calcium-entry blockers increase the intramyo-cardial pH and decrease the intramyocardial Pco2 of ischaemic canine myocardium. However, the evidence documenting improvements in myocardial acidosis and in myocardial resuscitability after administration of calcium-entry blockers during cardiac arrest is incomplete. We therefore compared the effects of verapamil (0.05 mg/kg) and diltiazem (0.075 mg/kg) with those of saline placebo in an established porcine model of cardiac arrest and cardiopulmonary resuscitation.
2. After verapamil, six of 11 animals were successfully resuscitated; after diltiazem, five of 10; and after saline placebo, six of 10. Coronary perfusion and mean aortic pressures together with end-tidal CO2 concentration during precordial compression were predictive of resuscitation, independently of the drug or placebo.
3. Coronary vein pH decreased to 6.91 ± 0.06 units (mean ± sem) with concurrent increases in Pco2 to levels exceeding 100 mmHg. Coronary vein lactate increased to a maximum of 7.5 ± 0.6 mmol/l. Coronary vein acidaemia was accompanied by decreases in intramyocardial pH to 6.64 ± 0.06 units. However, each of these differences between success and failure of resuscitation was unrelated to treatment with calcium-entry blockers.
4. Accordingly, neither verapamil nor diltiazem selectively altered coronary perfusion pressure, attenuated intramyocardial acidosis or improved resuscitability after porcine cardiac arrest and cardiopulmonary resuscitation.
A new method of analysing pulmonary quasi-static pressure-volume curves in normal subjects and in patients with chronic airflow obstruction
Authors: Gugger M. , Wraith P. K. , Sudlow M. F. 
Published: August 2015

1. Exponential analysis of lung pressure-volume curves is used to deal with the non-linearity of the pressure-volume relationship. A major problem of this procedure is to define the lower volume limit for exponential curve fitting.
2. In 12 healthy subjects and 24 patients with chronic airflow obstruction, a cubic function was fitted to the quasi-static pressure-volume curves to define an inflection point.
3. The exponential function of Colebatch et al. (Colebatch, H.J.H., Ng, C.K.Y. & Nikov, N. J. Applied Physiol. 1979; 46, 387–93) was then fitted to the data for volumes above the inflection point.
4. Exponential analysis with a cubic determination of an inflection point provides an objective way to describe the elastic properties of the human lungs in vivo.
Effect of lithium on the renal actions of α-human atrial natriuretic peptide in normal man
Authors: Freestone S. , Jeffrey R. F. , Bonner C. V. , Lee M. R. 
Published: August 2015

1. α-Human atrial natriuretic peptide (7.5 pmol min−1 kg−1) was infused intravenously into eight healthy men after pretreatment with lithium carbonate (750 mg) or placebo.
2. Baseline sodium excretion was significantly increased after lithium, but the natriuresis during infusion of α-human atrial natriuretic peptide was attenuated.
3. Similar decreases in plasma renin activity with infusion of α-human atrial natriuretic peptide occurred on both days.
4. Administration of lithium may be associated with pharmacological effects and further work is required to validate the use of lithium clearance as a marker of proximal renal tubular sodium handling.
Epidermal growth factor accelerates functional recovery from ischaemic acute tubular necrosis in the rat: Role of the epidermal growth factor receptor
Authors: Norman Jill , Tsau Yong-Kwei , Bacay Angelito , Fine Leon G. 
Published: August 2015

1. Severe, ischaemic, acute tubular necrosis was induced in rats by bilateral occlusion of the renal arteries. The experimental group received exogenous epidermal growth factor infused directly into the renal arterial circulation. Serum creatinine concentration was measured daily for 1 week. Epidermal growth factor receptor binding was measured by autoradiography of whole kidney sections. Renal cell proliferation was measured by incorporation of [3H]thymidine into DNA.
2. Serum creatinine concentration increased after acute tubular necrosis with a peak at 48 h and remained elevated above control levels after 7 days. Binding of radiolabelled epidermal growth factor occurred in all regions of the kidney 48 h after ischaemia. Treatment with exogenous epidermal growth factor attenuated the rise in serum creatinine by 4 days after acute tubular necrosis and after 7 days serum creatinine was lower than in animals that did not receive epidermal growth factor. Infusion of epidermal growth factor also increased renal DNA synthesis.
3. The increase in epidermal growth factor binding in the kidney after acute tubular necrosis and the attenuation of the increase in serum creatinine concentration by administration of exogenous epidermal growth factor, suggest a role for epidermal growth factor in recovery from ischaemic damage. The increase in DNA synthesis in response to epidermal growth factor indicates that its effect may be due, at least in part, to accelerated tubular cell proliferation.
Intrarenal angiotensin II inhibition influences the actions of atrial natriuretic peptide
Authors: Steele T. H. , Challoner-Hue L. 
Published: August 2015

1. We previously found that kidneys isolated from salt-restricted rats were refractory to atrial natriuretic peptide compared with kidneys from salt-loaded rats. Because the intrarenal tissue renin-angiotensin system may modulate renal responses to atrial natriuretic peptide, we examined the effect of dietary NaCl loading on the responses of isolated perfused kidneys from normal rats to atrial natriuretic peptide, before and after the addition of angiotensin II receptor antagonists or angiotensin I converting enzyme inhibitors to the perfusate.
2. Atrial natriuretic peptide increased the glomerular filtration rate and sodium excretion of kidneys from NaCl-loaded rats. The addition of angiotensin receptor antagonists or converting enzyme inhibitors partially reversed the increments in glomerular filtration rate but not the increments in sodium excretion, leading to an increased fractional sodium excretion. In the absence of atrial natriuretic peptide, these agents did not affect glomerular filtration or sodium excretion. Kidneys from NaCl-restricted rats did not respond to atrial natriuretic peptide or to the inhibitors and antagonists, either separately or in combination.
3. After NaCl loading, the intrarenal renin-angiotensin system may augment the glomerular response to atrial natriuretic peptide while simultaneously inhibiting the natriuretic response to atrial natriuretic peptide. However, activation of the intrarenal renin-angiotensin system is not responsible for the refractoriness of kidneys from salt-restricted rats to atrial natriuretic peptide.
Role of atrial natriuretic peptide in the increase in glomerular filtration rate induced by a protein meal
Authors: Tam S. C. , Tang L. S. , Lai C. K. , Nicholls M. G. , Swaminathan R. 
Published: August 2015

1. The increase in glomerular filtration rate after a protein meal is believed to be mediated by hormonal factors. Since natriuresis is often observed after a protein meal, it was postulated that the increase in glomerular filtration rate after a protein meal might be mediated by atrial natriuretic peptide.
2. Subjects were given a low, medium or high protein meal. Fluid intake was controlled so as to avoid significant extracellular fluid volume expansion. It was found that the creatinine clearance, the urea excretion, the fractional sodium excretion and the potassium excretion were elevated in all subjects after protein meals (P &lt;0.05). These effects were not observed in subjects given a carbohydrate control meal.
3. The plasma atrial natriuretic peptide concentrations remained unchanged in all subjects except those given a high protein meal (P &lt;0.05). There was no significant relationship between plasma atrial natriuretic peptide concentrations and creatinine clearance before or after a protein meal.
4. The data suggest that a high protein meal induces a minor increase in plasma atrial natriuretic peptide concentration, whereas a low or medium protein meal does not. It is unlikely that the change in creatinine clearance after a protein meal can be explained by a change in plasma atrial natriuretic peptide levels.
Aspects of protein metabolism after elective surgery in patients receiving constant nutritional support
Authors: Carli F. , Webster J. , Ramachandra V. , Pearson M. , Read M. , Ford G. C. , McArthur S. , Preedy V. R. , Halliday D. 
Published: August 2015

1. The present study was designed in an attempt to resolve conflicting views currently in the literature relating to the effect of surgery on various aspects of protein metabolism.
2. Sequential post-operative (2, 4 and 6 days) changes in whole-body protein turnover, forearm arteriovenous difference of plasma amino acids, glucose, lactate and free fatty acids, muscle concentration of free amino acids, RNA and protein, urinary nitrogen and 3-methylhistidine, plasma concentrations of insulin, cortisol and growth hormone, and resting metabolic rate, were measured in six patients undergoing uncomplicated elective total abdominal hysterectomy.
3. All patients received a constant daily diet, either orally or intravenously, based on 0.1 g of nitrogen/kg and an energy content of 1.1 times the resting metabolic rate for 7 days before and 6 days after surgery.
4. Whole-body protein turnover, synthesis and breakdown increased significantly 2 days after surgery (P &lt;0.05) and returned towards pre-operative levels thereafter.
5. Forearm release of branched-chain amino acids and alanine, and efflux of glucose and lactate, were enhanced 4 days after surgery (P &lt;0.05). Muscle glutamine and alanine concentrations were decreased on the fourth and sixth days after surgery (P &lt;0.05). The RNA/protein ratio (indicating the capacity for protein synthesis) was unaltered.
6. A significant increase in urinary nitrogen and 3-methylhistidine was observed on days 3 and 4 after surgery (P &lt;0.05). Thereafter, these parameters remained elevated, although failing to reach statistical significance.
7. The resting metabolic rate was significantly increased (P &lt;0.05) 2 days after surgery but the respiratory quotient (0.77) was unchanged.
8. These data support the contention that whole-body protein synthesis and breakdown increase after surgery. Differences observed pre- and post-operatively between leucine kinetic estimates and other methods of quantifying protein metabolism indicate that only like methodologies should be compared.
Substrate Utilization during Exercise in Chronic Cardiac Failure
Authors: Riley M. , Elborn J. S. , Bell N. , Stanford C. F. , Nicholls D. P. 
Published: August 2015

1. Skeletal muscle metabolism in chronic cardiac failure may be influenced by the many circulatory and neurohumoral adaptations in the condition. We investigated aerobic metabolism during exercise using indirect calorimetry in 15 patients with chronic cardiac failure and in 14 control subjects. Subjects exercised on a treadmill for 20 min at a steady-state submaximal workload.
2. Venous lactate levels were relatively constant throughout the exercise, although they were slightly greater in the patients with chronic cardiac failure than in the control subjects. The respiratory exchange ratio was lower in patients with chronic cardiac failure (0.777 ± 0.021 vs 0.833 ± 0.037, means ± sd; P &lt; 0.0002, Mann-Whitney U-test). Relative fat utilization, expressed as a percentage of total energy expenditure, was therefore greater in patients with chronic cardiac failure (71.8 ± 7.0 vs 54.1 ± 12.3%, P &lt; 0.0005) and this was mirrored in a lower carbohydrate utilization (24.7 ± 6.5 vs 43.3 ± 12.1%, P &lt; 0.0002). Levels of free fatty acids, glycerol and noradrenaline were greater in patients with chronic cardiac failure.
3. We conclude that there is an increased reliance on fat, as opposed to carbohydrate, metabolism during exercise in chronic cardiac failure, and that this may relate to the elevated catecholamine and free fatty acid levels present. This may be a compensatory mechanism to preserve muscle glycogen stores, but as fat utilization is less efficient in terms of oxygen consumed, this shift may further impair exercise capacity.
Distal Lithium Reabsorption in the Sodium-Restricted Rat is Not Dependent on the Urinary Sodium to Lithium Concentration Ratio
Authors: Shalmi Michael , Petersen Jørgen S. , Thomsen Klaus , Christensen Sten 
Published: August 2015

1. High fractional reabsorption of lithium occurs when rats and dogs are given a low sodium diet. This has been suggested to be due to the low tubular fluid sodium to lithium concentration ratio which arises during sodium restriction allowing transport mechanisms along the distal nephron segment to accept significant quantities of lithium instead of sodium by simple competition.
2. Clearance experiments in conscious water-loaded Wistar rats maintained on either a low sodium (6 mmol/kg) or a normal sodium (120 mmol/kg) diet were performed. The rats were infused with a solution of 120 mmol/l glucose and 10 mmol/l NaCl at a rate of 6 ml/h.
3. The median fractional excretion of lithium was 19.4% in the group with a normal sodium intake, and 2.5% in the group given a low sodium diet. The urine to plasma concentration ratio of lithium was 2.5 in the normal sodium group and 0.4 in the sodium-restricted group. The urinary sodium to lithium concentration ratio was 13 in the control group and 63 in the sodium-restricted group.
4. It is concluded that the increased fractional reabsorption of lithium initiated by a low sodium intake is not likely to be due to simple competition at distal tubular nephron sites between lithium and sodium.
Glutamine Metabolism in Skeletal Muscle of Glucocorticoid-Treated Rats
Authors: Ardawi M. Salleh M. , Jamal Yasir S. 
Published: August 2015

1. The effect of dexamethasone (30 μg day−-1 100 g−-1 body weight) on the regulation of glutamine metabolism was studied in skeletal muscles of rats after 9 days of treatment.
2. Dexamethasone resulted in negative nitrogen balance, and produced increases in the plasma concentrations of alanine (23.4%) and insulin (158%) but a decrease in the plasma concentration of glutamine (28.7%).
3. Dexamethasone treatment increased the rate of glutamine production in muscle, skin and adipose tissue preparations, with muscle production accounting for over 90% of total glutamine produced by the hindlimb.
4. Blood flow and arteriovenous concentration difference measurements across the hindlimb showed an increase in the net exchange rates of glutamine (25.3%) and alanine (90.5%) in dexamethasone-treated rats compared with corresponding controls.
5. Dexamethasone treatment produced significant decreases in the concentrations of skeletal muscle glutamine (51.8%) and 2-oxoglutarate (50.8%). The concentrations of alanine (16.2%), pyruvate (45.9%), ammonia (43.3%) and inosine 5′-phosphate (141.8%) were increased.
6. The maximal activity of glutamine synthetase was increased (21–34%), but there was no change in that of glutaminase, in muscles of dexamethasone-treated rats.
7. It is concluded that glucocorticoid administration enhances the rates of release of both glutamine and alanine from skeletal muscle of rats (both in vitro and in vivo). This may be due to changes in efflux and/or increased intracellular formation of glutamine and alanine.
Three Different Methods of Inhibiting Lipolysis in Human Chyme in Vitro: Efficiency and Effect on Phase Distribution of Lipids
Authors: Fine D. R. , Zentler-Munro P. L. , Northfield T. C. 
Published: August 2015

1. The efficiencies of three different methods of inhibiting fatty acid production in chyme have been evaluated. The effects of each method on the phase distribution of fatty acids after ultracentrifugation have been studied.
2. Chyme fatty acid concentrations were measured during a 4 h incubation (a) without an inhibitor, (b) after acid treatment, (c) after addition of p-bromophenyl-boronic acid and (d) after heating.
3. In a separate experiment, fresh chyme was incubated to allow equilibration of lipolysis. Aliquots were treated by each inactivation method and ultracentrifuged overnight to separate the phases. Total and micellar fatty acids and glycerides were measured.
4. In the first experiment, acid treatment completely inhibited fatty acid generation producing 4 h concentrations which were 93.4 ± 5.6% (mean ± sem) of initial values compared with 398.0 ± 54.0% (P &lt; 0.05) for uninhibited samples. p-Bromophenylboronic acid and heating gave significant but incomplete inhibition (132.9 ± 6.6% and 166.1 ± 15.2% of initial concentrations, respectively).
5. Ultracentrifugation disclosed five phases in all except the acid-treated samples, which had four. Micellar phase fatty acid concentrations were significantly higher in the acid-treated than in the untreated samples (2.6 ± 0.7 versus 1.7 ± 0.5 mmol/l, P = 0.05), as were glyceride concentrations (1.5 ± 0.4 vs 0.6 ± 0.3 mmol/l, P = 0.05).
6. It was concluded that acid treatment was the most efficient inhibitor of fatty acid production, but it disrupted the phases. p-Bromophenylboronic acid gave significant inhibition without causing phase disruption and was therefore the most useful inhibitor overall.
Regional Haemodynamic Effects of Captopril, Enalaprilat and Lisinopril in Conscious Water-Replete and Water-Deprived Brattleboro Rats
Authors: Muller A. F. , Gardiner S. M. , Compton A. M. , Bennett T. 
Published: August 2015

1. The regional haemodynamic effects of intravenous bolus doses of captopril, enalaprilat and lisinopril were assessed in conscious Brattleboro (i.e. vasopressin-deficient) rats, chronically instrumented with miniaturized pulsed Doppler probes and intravascular catheters.
2. Responses to incremental doses of each drug (spanning the median effective dose for the inhibition of the pressor response to angiotensin I) were examined in both water-replete and water-deprived states.
3. In the water-replete state, the haemodynamic profiles of captopril, enalaprilat and lisinopril were generally similar, with incremental doses causing rises in mesenteric and renal flow and, to a lesser extent, hindquarters flow. There were small tachycardias and only slight falls in mean blood pressure.
4. In the water-deprived state, the effects of all three drugs were greatly enhanced; tachycardic and hypotensive effects occurred together with increases in mesenteric, renal and hindquarters flows. However, for renal flow and renal vascular conductance the effectiveness of the drugs decreased in the order enalaprilat &gt; captopril &gt; lisinopril, whereas for mesenteric flow and mesenteric vascular conductance the order was captopril &gt; enalaprilat &gt; lisinopril.
5. Since marked haemodynamic actions were seen with doses one-tenth of the median effective dose for the inhibition of the pressor effect of angiotensin I, it is likely these effects were due to inhibition of angiotensin-converting enzyme, although not necessarily to inhibition of angiotensin II production. There were differences between the regional haemodynamic effects of the drugs at higher doses (10 × the median effective dose and 2 mg/kg), these differences supporting the proposition that in future it may be possible to design angiotensin-converting enzyme inhibitors with regionally selective haemodynamic effects.