bluuebunny/crossref_metadata_2025_split huggingface dataset:
Timing of deep breaths during rest and light exercise in man
Authors: Patil C. P. , Saunders K. B. , Sayers B. McA. 
Published: August 2015

1. We used digital filtering techniques and segmental analysis to dissect a series of respiratory variables into three components: (a) outlying values, including deep breaths or sighs; (b) random variation; (c) non-stationary baseline variation.
2. Records of about 30 min breathing were obtained from normal adults at rest and at 50 W exercise.
3. Deep breaths were defined as having a tidal volume &gt;2.5 sd above the mean.
4. We related these deep breaths to preceding trends in tidal volume and end-tidal partial pressure of CO2.
5. At rest, there was no relation between deep breaths and tidal volume, but the deep breaths were significantly clustered around the troughs in end-tidal partial pressure of CO2.
6. At 50 W exercise, there was no relation between deep breaths and end-tidal partial pressure of CO2, but the deep breaths were significantly clustered around tidal volume troughs.
7. Results obtained by pneumography were concordant with those obtained by using a mouthpiece to measure ventilation.
Ketone body metabolism in lean male adults during short-term starvation, with particular reference to forearm muscle metabolism
Authors: Elia M. , Wood S. , Khan K. , Pullicino E. 
Published: August 2015

1. Thirty-three arteriovenous forearm catheterization studies were carried out in 19 lean subjects starving for 12–14 h(n = 13), 30–36 h (n = 7) and 60–66 h (n = 13). Forearm blood flow was measured in order to calculate the flux of various substrates. At the same time, whole-body oxidation of fat, carbohydrate and protein was calculated using indirect calorimetry and urinary nitrogen excretion.
2. After an overnight fast (12–14 h), whole-body resting energy expenditure was accounted for by the oxidation of protein (15%), carbohydrate (17%) and fat (68%). At 30–36 h and 60–66 h of starvation, essentially all the non-protein energy was derived from the oxidation of fat (directly plus indirectly via ketone bodies).
3. After an overnight fast, acetoacetate and 3-hydroxybutyrate were taken up by forearm muscle at a rate which could account for 5% of the resting O2 consumption of this tissue. As starvation progressed, forearm muscle took up more acetoacetate and released 3-hydroxybutyrate so that the net uptake of ketone bodies was sufficient to account for about 10% of the resting O2 consumption at 30–36 h of starvation and about 20% at 60–66 h of starvation.
4. The uptake of circulating non-esterified fatty acids by forearm muscle accounted for a greater proportion of the forearm O2 consumption than the uptake of ketone bodies at all times studied. The release of lactate and alanine was significantly greater at 36–40 h and 60–66 h of starvation compared with 12–14 h of starvation, but that of glucose did not change significantly.
5. The results suggest that during early starvation: (a) the release of 3-hydroxybutyrate by muscle (36–66 h starvation) contributes to the circulating 3-hydroxybutyrate concentration, (b) the contribution of ketone bodies to oxidative metabolism in lean subjects is variable but considerably lower than the generally accepted values in obese individuals, and (c) the dominant energy source for the resting muscle of lean individuals between 12 and 66 h of starvation is non-esterified fatty acids.
Cardiac output and oxygen uptake in patients with renal failure
Authors: Kong C. H. , Thompson F. D. , Imms F. J. 
Published: August 2015

1. Cardiac index, oxygen uptake and haemoglobin concentration have been measured in eight patients with end-stage renal failure, and the values compared with those in eight healthy control subjects. Assuming the arterial blood to be 97% saturated, the oxygen saturation of mixed venous blood has been calculated.
2. Cardiac index was lower in the patients (2.45 ± 0.42 litres min−1 m−2) compared with the control subjects (3.74 ± 0.17 litres min−1 m−2). Oxygen uptake was reduced from 147 ± 16 ml STP min−1 m−2 in the control subjects to 112 ± 9 ml STP min−1 m−2 in the patients.
3. Oxygen saturation of mixed venous blood was 53 ± 8% in the patients compared with 79 ± 2% in the control subjects, suggesting some degree of tissue hypoxia. If oxygen uptake were not reduced in renal failure, then the mixed venous blood oxygen saturation would be as low as 40%.
4. The oxygen saturation of blood sampled from the superior vena cava of patients with renal failure was 57 ± 6%.
5. The data on oxygen uptake and venous oxygen saturation suggest that in the patients with end-stage renal failure, the low values of cardiac index, previously measured by impedance cardiography, are accurate.
Renal Acidification Defect Induced by Lithium in Control and Acidotic Rats
Authors: MacLaughin M. , Aires M. Mello 
Published: August 2015

1. The aim of this work was to contribute to a better understanding of the mechanism by which Li+ administration impairs renal tubular acidification.
2. The kinetics of tubular acidification in the mid-proximal and distal convoluted tubules were studied by measuring intratubular pH using Sb microelectrodes during stopped-flow microperfusion with Krebs-Ringer bicarbonate (30 mmol/l) buffer. Four groups of male Wistar rats were utilized in this study: control, control plus lithium (C + Li+; one intraperitoneal injection of LiCl of 4 mmol l−1 day−1 kg−1 for 4 days), acidotic and acidotic plus lithium (A+ Li+).
3. In C + Li+ rats, the half-time of acidification was significantly higher than in control rats (P &lt; 0.01), in both the mid-proximal tubule (11.3 ± 0.34 vs 6.73 ± 0.22 s) and the distal convoluted tubule (17.5 ± 0.31 vs 11.5 ± 1.02 s), and net HCO3− reabsorption was lower in both the mid-proximal tubule and the distal convoluted tubule. The effects of Li+ on tubular acidification kinetics were similar in acidotic rats.
4. A net Na+ flux, as measured by the Gertz split-droplet method, was significantly decreased in the mid-proximal tubule (P &lt; 0.01) in C + Li+ rats compared with control rats (2.14 ± 0.17 vs 4.07 ± 0.39 nmol s−1 cm−2).
5. The transepithelial potential difference in the distal convoluted tubule was significantly lower (P &lt; 0.01) in C + Li+ rats than in control rats (–7.50 ± 1.50 vs −20.5 ± 1.12 mV).
6. These findings suggest that Li+ causes a reduction in the apical Na+ gradients in both tubular segments, thereby decreasing the favourable driving force for H+ secretion.
Effect of Aspirin Infusions on Platelet Function in Humans
Authors: Wilson K. M. , Siebert D. M. , Duncan E. M. , Somogyi A. A. , Lloyd J. V. , Bochner F. 
Published: August 2015

1. The inhibitory effects of aspirin on platelet function in vitro have been shown to be both time (over 3 h) and concentration (1–10 μmol/l) dependent.
2. To determine if these effects occurred in vivo, four volunteers received intravenous infusions on four occasions, to give constant plasma aspirin concentrations of 0, 1, 2 and 4 μmol/l over 3 h. Infusions were performed at intervals of at least 2 weeks.
3. Before and during the infusions, blood was taken for assay of aspirin concentrations, and measurements of platelet aggregation in response to collagen, adenosine 5′-pyrophosphate and arachidonate. Thromboxane generation after stimulated platelet aggregation and whole-blood coagulation was also measured.
4. At each aspirin concentration, both platelet aggregation and thromboxane generation in response to collagen and arachidonate were inhibited progressively over the 3 h infusion period. Greatest inhibition was seen during the 4 μmol/l infusion, which produced maximal or near-maximal inhibition by the third hour.
5. Thromboxane generated during whole-blood coagulation was similarly inhibited in both a time- and concentration-dependent manner throughout all aspirin infusions.
6. The progressive nature of the inhibition of platelet function with these low aspirin concentrations may be due to either slow aspirin transport across the platelet membrane or delayed interaction with cyclo-oxygenase.
Active and Inactive Urinary Kallikrein in Man: Effects of Diuresis and Antidiuresis
Authors: Waller Derek G. , Bhatia Satvinder S. , Campbell Sara K. , Albano Janet D. M. , Millar J. Gavin B. 
Published: August 2015

1. The urinary excretion of active and inactive kallikrein was studied in volunteers during diuresis induced by water loading or oral frusemide and during antidiuresis induced by desamino-d-arginine-vasopressin.
2. During acute oral water loading, excretion of active kallikrein was unchanged, despite high urine flow rates and low urine osmolalities being achieved. Excretion of inactive kallikrein correlated with the urine flow rate.
3. After desamino-d-arginine-vasopressin in eight water-loaded and six normally hydrated subjects, excretion of inactive kallikrein also correlated with the urine flow rate. There were no significant changes in the excretion of active kallikrein.
4. After frusemide there was a small transient increase in excretion of active kallikrein 1–2 h after dosing which coincided with the maximum diuresis and natriuresis. Excretion of inactive kallikrein again correlated with urine flow rate but the regression relationship between the two variables was different for water-load-induced and frusemide-induced diuresis.
5. These studies do not support a role for urinary kallikrein in the modulation of the antidiuretic action of vasopressin, but suggest that it may contribute to the natriuretic action of frusemide.
Haemodynamic and Metabolic Effects of Infused Adenosine in Man
Authors: Edlund Anders , Sollevi Alf , Linde Birgitta 
Published: August 2015

1. Haemodynamic and metabolic effects of intravenous infusion of adenosine, an endogenous vasodilator, were studied in healthy humans.
2. Catheters were inserted into pulmonary and brachial arteries and into the hepatic and subclavian veins. Cardiac output was determined according to the Fick principle, and splanchnic blood flow was measured by using extraction of Indocyanine Green. Skin blood flow was estimated by a laser Doppler technique, calf blood flow by venous occlusion plethysmography and skeletal muscle and adipose tissue blood flow by a local isotope clearance technique.
3. Adenosine (infused in steps from 40 to 80 μg min−-1 kg−-1 into a central vein) elicited a gradual reduction in the peripheral vascular resistance to less than 50% of the basal level. There was a slight increase in the systemic blood pressure, but the pulmonary arterial and the ventricular filling pressures were unchanged. Cardiac output was doubled, accomplished by a combination of a positive chronotropic effect and an increase in stroke volume, which may be secondary to diminished peripheral resistance.
4. Skin blood flow increased by 100% at 50 μg of adenosine min−-1 kg−-1, whereas splanchnic blood flow rose significantly at 60 μg of adenosine min−-1 kg−-1. Blood flow in the calf, gastrocnemius muscle and adipose tissue did not change significantly.
5. Arterial concentrations of noradrenaline and adrenaline increased by 62 and 43%, respectively, during infusion of adenosine. Arterial levels of glycerol were depressed by more than 50%, but those of glucose and pyruvate were unchanged.
6. In conclusion, exogenous adenosine caused a marked systemic vasodilatation, with different responsiveness in the investigated vascular beds. The vasodilatation occurred in the presence of an increase in generalized sympathetic activity. Adipose tissue blood flow was unaltered despite a considerable reduction in fat mobilization.
Response of Serum Interleukin-6 in Patients Undergoing Elective Surgery of Varying Severity
Authors: Cruickshank A. M. , Fraser W. D. , Burns H. J. G. , Van Damme J. , Shenkin A. 
Published: August 2015

1. Recent studies have suggested that interleukin-6 is a major mediator of the acute-phase protein response in man. The aim of the present study was to investigate the relationships between the response of serum interleukin-6 to surgery, the type of surgical procedure performed and the response of serum C-reactive protein.
2. Timed venous blood samples were taken from 26 patients in five broad surgical categories (minor surgery, cholecystectomy, hip replacement, colorectal surgery and major vascular surgery). C-reactive protein and interleukin-6 were measured in each sample.
3. Serum interleukin-6 rose within 2–4 h of incision in all patients and the magnitude of the response differed among the various surgical groups. The response of interleukin-6 correlated (r = 0.80, P &lt; 0.001) with the duration of surgery. In contrast, serum C-reactive protein was not detectable after minor surgery (&lt; 10 mg/l) and the response of C-reactive protein did not differ among the more major surgical groups. The response of interleukin-6 showed a weak, but significant, correlation with the response of C-reactive protein (r = 0.67, P &lt; 0.001).
4. We conclude that serum interleukin-6 is a sensitive, early marker of tissue damage. In general, the greater the surgical trauma, the greater the response of serum interleukin-6 and the greater the peak serum concentration of interleukin-6. Our results are consistent with a role for interleukin-6 in the induction of C-reactive protein synthesis.
Simultaneous Assessment of Intestinal Permeability and Lactose Tolerance with Orally Administered Raffinose, Lactose and 1-Arabinose
Authors: Lobley R. W. , Burrows P. C. , Warwick R. , Dawson D. J. , Holmes R. 
Published: August 2015

1. In order to develop an improved differential sugar absorption test for simultaneously assessing intestinal permeability and lactose intolerance, methods were established for determining raffinose, lactose and l-arabinose in human urine. Using NAD(P)H-coupled enzymatic assays and fluorimetry, each sugar was measurable over a concentration range of approximately 3–300 μmol/l in diluted urine specimens.
2. After an overnight fast, 40 normal volunteers drank an iso-osmotic solution containing raffinose, lactose and l-arabinose. The median 5 h urinary sugar excretion was 0.26% of the ingested raffinose, 0.05% of lactose and 17.5% of l-arabinose.
3. In 143 patients with gastrointestinal disease, excretion of both ingested raffinose and lactose was significantly increased in coeliac disease in relapse or in partial remission and in Crohn's disease, but not in the irritable bowel syndrome, coeliac disease in remission or ulcerative colitis. Excretion of lactose, but not raffinose, was increased in patients with mucosal lactase deficiency, whereas excretion of l-arabinose was reduced in all disease groups except ulcerative colitis.
4. Discrimination between diseases was poor when based on individual sugar recoveries, but improved dramatically when excretion was expressed relative to that of l-arabinose. The raffinose/l-arabinose excretion ratio, an index of intestinal permeability, was &gt; 0.08 in 15/15 untreated coeliac patients but &lt; 0.06 in all normal subjects and in 9/9 lactase-deficient patients, 15/16 recovered coeliac patients, 5/6 patients with ulcerative colitis, 13/16 patients with Crohn's disease and 61/62 patients with irritable bowel syndrome.
5. The lactose/l-arabinose excretion ratio, an index of lactose maldigestion, was &gt;0.01 in 9/9 lactase-deficient patients and 14/15 untreated coeliac patients, but &lt; 0.008 in all normal subjects, recovered coeliac patients and ulcerative colitis patients, and in 11/16 patients with Crohn's disease and 58/62 patients with irritable bowel syndrome.
6. The test reliably detected the altered intestinal permeability of coeliac disease and small-bowel Crohn's disease, and differentiated between lactosuria due to lactase deficiency and that secondary to villous atrophy. With automation of the analysis, it would be suitable for widespread use in screening for intestinal disease.
Kinetics of Influx of Peptides and Amino Acids into Hamster Jejunum in Vitro: Physiological and Theoretical Implications
Authors: Burston D. , Matthews D. M. 
Published: August 2015

1. This paper reports a comparison of the kinetics of influx into hamster jejunum of a series of dipeptides of neutral, basic and acidic amino acids, and a tripeptide of neutral amino acids, with those of corresponding free amino acids.
2. Kt, the substrate concentration at which the transport rate is half the maximal transport rate, and Vmax, the maximal transport rate, were more similar from one peptide to another than among amino acids, with the result that, over a wide range of concentrations, rates of influx of individual peptides varied much less than those of amino acids.
3. It is suggested that this may account for the rates of absorption of amino acids being closely related to the amino acid composition of the protein fed, instead of being widely dissimilar as with corresponding mixtures of free amino acids.
4. With neutral amino acids, both Kt and Vmax. fell with increasing length of the side-chain, as observed on many previous occasions. This did not occur with the corresponding homologous dipeptides, which shows that the hypothesis that the apparent affinity for transport is related to the lipophilic properties of the side-chain cannot be applied to peptides.
Renal Function in Rats with Essential Fatty Acid Deficiency
Authors: Hjelte L. , Larsson M. , Alvestrand A. , Malmborg A.-S. , Strandvik B. 
Published: August 2015

1. Renal function was studied in 50-, 70-, 90- and 200-day-old rats with essential fatty acid deficiency. The pharmacokinetics of tobramycin was investigated in 90-day-old essential fatty acid-deficient rats.
2. A higher glomerular filtration rate and a higher serum concentration of urea were seen in 50-day-old essential fatty acid-deficient rats compared with age-matched controls. Later, the glomerular filtration rate progressively deteriorated in parallel with a decline in effective renal plasma flow and with a concomittant rise in serum levels of urea and creatinine. The serum concentration of protein was lower in the rats with essential fatty acid deficiency and that of sodium was higher than in the control rats. The non-renal clearance of tobramycin was increased in the rats with essential fatty acid deficiency.
3. The early hyperfiltration in essential fatty acid-deficient rats with the subsequent fall in glomerular filtration rate, which was paralleled by a rise in serum levels of urea and creatinine, as well as the increased non-renal clearance of tobramycin, are in accordance with the clinical manifestations of cystic fibrosis. Rats with essential fatty acid deficiency might be a useful model with which to study the pathophysiological renal changes in cystic fibrosis related to the progressive essential fatty acid deficiency in this disease.
Effect of Facial Cooling on Mucosal Blood Flow in the Mouth in Humans
Authors: Fouke Janie M. , Wolin Alexis D. , Bowman H. Frederick , McFadden E. Regis 
Published: August 2015

1. To determine the effects of facial cooling on intraoral thermal events, we placed a thermal conductivity sensor on the buccal surface of the left cheek in six normal and six asthmatic subjects. Room temperature and cold stimuli were then applied to the integument surface of both sides of the face while mucosal surface temperature and thermal conductivity, as an index of blood flow, were recorded.
2. The room temperature challenge had no effect. Application of the cold stimulus to the exterior of the left cheek caused a monotonic decrease in temperature in the mouth in all subjects and was associated with a change in thermal conductivity in which blood flow increased and then fell to baseline despite a continued drop in temperature. These responses were purely local in that cooling of the right side of the face did not change the temperature or blood flow on the left side. No differences were noted between the asthmatic and normal subjects.
3. The data indicate that lowering the temperature of the skin of the face produces significant alterations in the thermal environment within the mouth. With facial cooling, buccal temperature falls and mucosal blood supply transiently rises. This effect appears to be a purely local thermally mediated event. Facial pressure and cutaneous reflexes do not play a role. The above changes may contribute to the conditioning of inspired air during oral breathing.
Effect of Sodium-Transport Inhibitors on Bronchial Reactivity in Vivo
Authors: Knox Alan J. , Britton John R. , Tattersfield Anne E. 
Published: August 2015

1. We have recently shown that ouabain, an inhibitor of Na+/K+-adenosine triphosphatase, causes contraction of bovine and human airways in vitro, and that amiloride causes relaxation and inhibits receptor-operated contraction in bovine trachealis.
2. To determine whether such drugs alter bronchial reactivity in vivo, we have studied the effect of oral digoxin (an inhibitor of Na+/K+-adenosine triphosphatase) and oral and inhaled amiloride on bronchial reactivity to histamine in three double-blind, placebo-controlled studies.
3. Histamine reactivity was measured as the provocative dose causing a 20% reduction in the forced expiratory volume in 1 s (PD20FEV1) or, when normal subjects were included, the provocative dose causing a 35% reduction in the specific airways conductance (PD35sGaw); the results are given as geometric mean values.
4. In study 1, 13 atopic asthmatic subjects were given 20 mg of oral amiloride or placebo on separate days. Two hours after the drug, the geometric mean PD20FEV1 for histamine was 0.43 μmol after amiloride and 0.54 μmol after placebo (95% confidence intervals for the difference: 0.9 to −0.2 doubling doses of histamine; P = 0.2).
5. In study 2, six normal and 24 atopic asthmatic men inhaled 10 ml of 10−2 mol/l amiloride or diluent control in a crossover study. The mean values of PD35sGaw for histamine immediately after inhalation of amiloride and placebo were 3.0 μmol and 4.3 μmol, respectively, in the normal subjects (95% confidence intervals for the difference: −0.53 to 1.52 doubling doses, P = 0.2), and 0.33 μmol and 0.29 μmol in the asthmatic subjects (95% confidence intervals for the difference: −0.95 to 0.57 doubling doses; P = 0.6).
6. In study 3, 24 atopic asthmatic men were treated for 7 days with placebo or oral digoxin (1.5 mg loading dose plus 0.25 mg twice daily for 6 days). The PD20FEV1 for histamine was measured before, 12 h after the loading dose and on day 7 of treatment. The change in PD20FEV1 did not differ significantly after digoxin and placebo, after either 1 day's treatment [mean (95% confidence intervals) difference: 0.56 doubling dose (−0.37 to 1.5 doubling dose)] or 7 day's treatment [mean (95% confidence intervals) difference: 0.3 doubling dose (−1.23 to 1.8 doubling doses)].
7. Although our work in vitro has suggested that membrane sodium transport may play an important role in determining airway smooth muscle contractility, we have been unable to demonstrate any effect of the sodium-transport inhibitors amiloride and digoxin on histamine reactivity in these studies.