bluuebunny/crossref_metadata_2025_split huggingface dataset:
Renal filtration, reabsorption and excretion of aluminium in the rat
Authors: Lote C. J. , Wood J. A. , Saunders H. C. 
Published: August 2015

1. Plasma and urinary aluminium levels, and renal function, were investigated in a control group of rats (n = 5) and in two groups that received an intravenous bolus dose of aluminium chloride (either 25 μg or 800 μg of aluminium, n = 7 and 5, respectively).
2. In the control group (plasma aluminium concentration 76.8 ± 14.2 ng/ml), 59.4 ± 3.5% of the plasma aluminium was ultrafilterable. The percentage ultrafilterable after the administration of 25 μg of aluminium was 41.9 ± 7.8 (plasma concentration 154.3 ± 18.6 ng/ml). However, after administration of 800 μg of aluminium, to give a plasma concentration of 19800 ± 2956 ng/ml, only 1.06 ± 0.13% was ultrafilterable.
3. Such results have generally been interpreted as indicating an increase in protein-binding of aluminium with increasing aluminium concentration. In buffered aqueous solutions of aluminium chloride at pH 7.4, with an aluminium concentration of 189 ± 6 ng/ml, 96.12 ± 0.02% was ultrafilterable (n = 6). This concentration is comparable with that attained in the low-dose (25 μg) aluminium group of animals and suggests that the difference between the ultrafilterable percentage of aluminium in plasma compared with that in aqueous solution is indeed due to the binding of aluminium to high Mr material (proteins). In contrast, however, in an aqueous buffered (pH 7.4) solution containing 28200 ng of aluminium/ml, only 1.05 ± 0.09% was ultrafilterable. This indicates insolubility (i.e. colloid formation) of the aluminium at this high concentration. The same percentage (1.06 ± 0.13) was ultrafilterable from plasma from the high-dose (800 μg) aluminium group with a plasma aluminium concentration of 19 800 ± 2956 ng/ ml. This low ultrafilterable fraction is thus attributable to the insolubility of aluminium at this concentration, rather than to protein binding.
4. The fractional excretion of aluminium in the control group was approximately 10%. It was somewhat higher in the low-dose aluminium group, and reached 53% in the high-dose aluminium group. Nevertheless, it is clear that the kidneys are inefficient at excreting aluminium, so that after aluminium administration there is a prolonged period (several hours) during which the plasma aluminium concentration remains elevated and thus tissue deposition may occur.
Hepatic blood flow and metabolism in severe falciparum malaria: clearance of intravenously administered galactose
Authors: Pukrittayakamee S. , White N.J. , Davis T. M. E. , Looareesuwan S. , Supanaranond W. , Desakorn V. , Chaivisuth B. , Williamson D. H. 
Published: August 2015

1. Hypoglycaemia and lactic acidosis are important manifestations of severe falciparum malaria. To investigate hepatic gluconeogenesis in acute falciparum malaria, liver blood flow and galactose clearance were estimated in seven adult patients with moderately severe infection and seven patients with severe infection (three of whom died later). Nine patients were restudied in convalescence.
2. Liver blood flow, determined from the plasma clearance of Indocyanine Green, was lower in acute illness than in convalescence [16.1 (7.0) versus 23.9 (7.2) ml min−1 kg−1, mean (sd)], but this difference was not statistically significant (P= 0.15). There was a significant inverse correlation between admission venous plasma lactate concentrations and the liver blood flow estimated from the clearance of Indocyanine Green (rs = 0.71, P = 0.004).
3. The plasma clearance of galactose after intravenous injection was similar in the acute [15.4 (4.90) ml min−1 kg−1] and convalescent study [12.8 (2.1) ml min−1 kg−1]. The ratio of galactose clearance to Indocyanine Green clearance was significantly higher in acute disease [1.41 (0.51)] than in convalescence [0.70 (0.34)], largely because of the elevated ratios in severely ill patients [1.48 (0.50)].
4. The rise in blood glucose concentration after galactose administration was significantly higher during acute illness [1.48 (0.72) mmol/l] than in convalescence [0.67 (0.41) mmol/l, P = 0.022], but the insulin response was similar, indicating reduced tissue insulin sensitivity. There was no significant change in the plasma concentrations of other metabolites (lactate, pyruvate, alanine and triacylglycerol) in either study.
5. These results suggest that the segment of the glycolytic pathway between galactose and glucose is unimpaired in patients with severe falciparum malaria. Since galactose does not stimulate insulin secretion directly and does not appear to increase plasma lactate concentrations, this simple sugar may be an alternative to glucose in the treatment of malaria-associated hypoglycaemia.
Location of enkephalinase and functional effects of [Leu5] enkephalin and inhibition of enkephalinase in the feline main pancreatic and bile duct sphincters
Authors: Thune A. , Jivegård L. , Pollard H. , Moreau J. , Schwartz J. C. , Svanvik J. 
Published: August 2015

1. Morphological studies have demonstrated enkephalinergic nerve fibres in proximity to the sphincter of Oddi, and opiates are known to contract this sphincter. In this study, the flow resistances in the common bile duct and main pancreatic duct sphincters were studied simultaneously in anaesthetized cats using a perfusion technique.
2. Naloxone did not affect the activity of these sphincters under basal conditions, indicating that there is no basal enkephalinergic tone.
3. The response to [Leu5]enkephalin (0.015–15 μg/kg), morphine (1 mg/kg) and ketamine (10 mg/kg) was a naloxone-sensitive increased activity in the sphincters with a raised frequency of phasic contractions. The threshold dose for an effect of [Leu5]enkephalin on the sphincter of Oddi was 0.015 μg/kg and a maximal response was observed at 0.75 μg/kg. There were no differences in the response of the main pancreatic duct sphincter and the bile duct sphincter to the different drugs.
4. Immunoautoradiographic studies demonstrated enkephalinase in the spincter of Oddi.
5. Acetorphan (3 mg/kg intravenously), which inhibits endogenous enkephalinase both in the peripheral and the central nervous system when administered parenterally, caused a naloxone-sensitive contraction, whereas thiorphan (3–20 mg/kg), an enkephalinase inhibitor that does not easily penetrate the blood-brain barrier, had no effect on the sphincter of Oddi.
6. These results show that endogenous and exogenous opiates influence the function of the feline sphincter of Oddi and that enkephalins may be involved in the physiological control of this sphincter, although not under basal conditions.
Adaptation to a diet low in protein: effect of complex carbohydrate upon urea kinetics in normal man
Authors: Langran M. , Moran B. J. , Murphy J. L. , Jackson A. A. 
Published: August 2015

1. Urea kinetics were measured by using prime/intermittent oral doses of [15N15N]urea in five healthy men taking formula diets adequate in energy and containing either 70 or 35 g of protein/day. In some studies the low-protein diet was supplemented with non-starch polysaccharides in the form of ispaghula husk or ripe bananas.
2. On the 70 g of protein/day diet urea production was 132% of intake. Only 54% of the urea produced was excreted in the urine with 46% being salvaged in the colon; 90% of the salvaged nitrogen was retained in the metabolic nitrogen pool.
3. On the 35 g of protein/day diet the small decrease in urea production rate compared with that on the 70 g of protein/day diet was not significant, but only 36% of the urea produced was excreted in urine, with the majority, 64%, being salvaged.
4. The extent of urea-nitrogen salvaging on the 35 g of protein/day diet was similar in magnitude to the decrease in nitrogen intake, with the effect that the sum of intake and salvaged nitrogen did not differ between the 35 and the 70 g of protein/day diets. This implies that quantitative control is exerted over the rate at which urea nitrogen is salvaged.
5. The addition of non-starch polysaccharides to the 35 g of protein/day diet had a demonstrable effect upon faecal weight and composition, but did not exert any significant influence upon urea kinetics.
6. It is concluded that large changes in the rate of urea production are not necessary for adaptation to a low-protein diet, rather the salvaging of urea nitrogen in the lower bowel appears to be an important mechanism through which the body adapts to a low-protein diet. The salvaging of urea nitrogen by the colon makes an important contribution to the conservation of body nitrogen.
Effect of increased free fatty acid supply on glucose metabolism and skeletal muscle glycogen synthase activity in normal man
Authors: Johnson A. B. , Argyraki M. , Thow J. C. , Cooper B. G. , Fulcher G. , Taylor R. 
Published: August 2015

1. Experimental elevation of plasma non-esterified fatty acid concentrations has been postulated to decrease insulin-stimulated glucose oxidation and storage rates. Possible mechanisms were examined by measuring skeletal muscle glycogen synthase activity and muscle glycogen content before and during hyperinsulinaemia while fasting plasma non-esterified fatty acid levels were maintained.
2. Fasting plasma non-esterified fatty acid levels were maintained in seven healthy male subjects by infusion of 20% (w/v) Intralipid (1 ml/min) for 120 min before and during a 240 min hyperinsulinaemic euglycaemic clamp (100 m-units h−1 kg−1) combined with indirect calorimetry. On the control day, 0.154 mol/l NaCl was infused. Vastus lateralis muscle biopsy was performed before and at the end of the insulin infusion.
3. On the Intralipid study day serum triacylglycerol (2.24 ± 0.20 versus 0.67 ± 0.10 mmol/l), plasma non-esterified fatty acid (395 ± 13 versus 51 ± 1 μmol/l), blood glycerol (152 ± 2 versus 11 ± 1 μmol/l) and blood 3-hydroxybutyrate clamp levels [mean (95% confidence interval)] [81 (64–104) versus 4 (3–5) μmol/l] were all significantly higher (all P &lt; 0.001) than on the control study day. Lipid oxidation rates were also elevated (1.07 ± 0.07 versus 0.27 ± 0.08 mg min−1 kg−1, P &lt; 0.001). During the clamp with Intralipid infusion, insulin-stimulated whole-body glucose disposal decreased by 28% (from 8.53 ± 0.77 to 6.17 ± 0.71 mg min−1 kg−1, P &lt; 0.005). This was the result of a 48% decrease in glucose oxidation (3.77 ± 0.32 to 1.95 ± 0.21 mg min−1 kg−1, P&lt;0.001), with no significant change in nonoxidative glucose disposal (4.76 ± 0.49 to 4.22 ± 0.57 mg min−1 kg−1, not significant).
4. Basal and insulin-stimulated glycogen synthase activities (13.1 ± 1.9 versus 11.4 ± 2.3% and 30.8 ± 2.3 versus 27.6 ± 4.5%, respectively) were unaffected by the increased plasma non-esterified fatty acid levels. Similarly, basal (36.1 ± 2.7 versus 37.2 ± 1.4 μmol/g) and stimulated (40.0 ± 0.6 versus 37.6 ± 4.4 μmol/g) muscle glycogen levels were unaltered. Insulin-stimulated hexokinase activity was also not affected (0.52 ± 0.08 versus 0.60 ± 0.08 units/g wet weight).
5. Maintenance of plasma non-esterified fatty acid levels at fasting values resulted in an increase in lipid oxidation and was associated with a decrease in insulin-stimulated whole-body glucose uptake and glucose oxidation rates, but no change in non-oxidative glucose disposal. Increased plasma non-esterified fatty acid levels did not appear to have a direct inhibitory effect on glycogen synthase activity or storage of glucose as glycogen at these insulin levels.
Interactions between hypoxic and almitrine-induced vasoconstriction in the rat lung
Authors: Russell P. C. , Emery C. J. , Nicholl J. , Barer G. R. , Howard P. 
Published: August 2015

1. To test whether almitrine might improve the arterial partial pressure of O2 in patients with chronic obstructive airways disease by improvement of ventilation-perfusion matching, we looked at the interaction between hypoxic and almitrine-induced vasoconstriction in isolated rat lungs perfused with blood at constant flow. Increases in pressure represented increases in resistance.
2. Almitrine, given in increasing doses between challenges with 2% O2, enhanced hypoxic vasoconstriction at low doses but attenuated it at high doses.
3. Stimulus-response curves to hypoxia of increasing severity gave a sigmoid curve.
4. Almitrine solvent caused small changes in pulmonary artery pressure and shifted the stimulus-response curve slightly in a parallel fashion.
5. Small doses of almitrine enhanced the action of mild to moderate hypoxia, medium doses attenuated moderately severe hypoxia, whereas high doses depressed vasoconstriction due to all degrees of hypoxia.
6. These effects of almitrine on hypoxic vasoconstriction were compared with the effect of solvent by analysis of variance; the results substantiated significant enhancement of hypoxia by small doses and attenuation by large doses.
7. In patients, if similar effects apply, small doses of almitrine would assist ventilation-perfusion matching, but large doses might worsen it.
8. Almitrine-induced vasoconstriction was attenuated by a fall in perfusate temperature in a similar manner to hypoxic vasoconstriction. It was also attenuated by three drugs, chlorpheniramine, propanolol and diethylcarbamazine, all of which also decrease hypoxic vasoconstriction. The similarity between hypoxic and almitrine-induced pulmonary vasoconstriction is further confirmed.
Leg extensor power and functional performance in very old men and women
Authors: Bassey E. Joan , Fiatarone Maria A. , O'neill Evelyn F. , Kelly Margaret , Evans William J. , Lipsitz Lewis A. 
Published: August 2015

1. Residents of a chronic care hospital (13 men of mean age 88.5 ± 6 sd years and 13 women of mean age 86.5 ± 6 sd years) who had multiple pathologies were assessed for leg extensor capability in several ways.
2. A custom-built rig was used to assess leg extensor power, that is, maximal power output over less than 1 s in a single extension of one leg. Performance measures were obtained by timing chair rises (from a standard chair 0.43 m high), stair climbing (four risers, total height 0.635 m) and a walk (6.1 m). For each measurement the best of several trials were recorded as definitive.
3. Leg extensor power was significantly correlated with all performance measures, but the performance measures were not related to each other except for chair rising and walking speed.
4. Women had significantly less extensor power than men, but their power explained more of the variance in performance, e.g. power accounted for 86% of the variance in walking speed.
5. There was no relation within the group between age and any of the variables measured.
6. Measurement of leg extensor power in frail elderly people may prove useful in focusing effective rehabilitation programmes.
Cutaneous vascular responses and thermoregulation in relation to age
Authors: Khan F. , Spence V. A. , Belch J. J. F. 
Published: August 2015

1. Sympathetic vasoconstrictor responses to inspiratory gasp and contralateral arm cold challenge were assessed in fingertip skin in relation to age and were correlated with vasoconstrictor ability during body cooling. The above relationship was also examined in diabetic patients in whom vasoconstrictor responses to inspiratory gasp and contralateral arm cold challenge had been shown previously to be markedly impaired.
2. Vasoconstrictor responses to inspiratory gasp and contralateral arm cold challenge, measured by laser Doppler flowmetry, were significantly reduced in the elderly group, although individual responses varied from normal to absent, and they also had a considerably greater variability as measured on three separate occasions than seen in young subjects. Discriminant analysis showed that, from each of three occasions, 65% of vasoconstrictor responses were abnormal in the elderly group.
3. Body cooling was performed by reducing the environmental temperature from 40°C to 12°C, and the time taken for blood flow to fall to 75%, 50% and 25% of the pre-cooling level (VC75, VC50, VC25, respectively) was calculated. Vasoconstriction was rapid in young subjects and was consistent with good vasoconstrictor responses to inspiratory gasp and contralateral arm cold challenge. In the elderly group, vasoconstriction was slower, but only the VC25 value differed significantly [elderly group, 13.3(7.9–31.0) min, young group, 5.7(2.7–15.5) min; median (interquartile range); P &lt; 0.05]. A poor vasoconstrictor response to contralateral arm cold challenge did not always correlate with an impaired response to body cooling in the elderly group, but, importantly, a diminished vasoconstrictor response to body cooling, with no spontaneous sympathetic vasoconstrictor bursts, was associated with an impaired vasoconstrictor response to contralateral arm cold challenge. Diabetic patients all had markedly reduced vasoconstrictor responses to inspiratory gasp, contralateral arm cold challenge and body cooling.
4. It is concluded that elderly subjects have diminished sympathetic vasoconstrictor responses. This may be a significant factor contributing to thermoregulatory impairment in the elderly, thereby rendering them more susceptible to the harmful effects of cold weather.
Effects of cyclosporin A on glomerular barrier function in the nephrotic syndrome
Authors: Zietse Robert , Wenting Gerrit J. , Kramer Pieter , Schalekamp Maarten A. , Weimar Willem 
Published: August 2015

1. To elucidate the mechanisms by which cyclosporin A diminishes proteinuria, we studied 20 patients with severe nephrotic syndrome. Biopsy-established pathologies included minimal change disease (n = 5), membranous glomerulopathy (n = 6), membranoproliferative glomerulonephritis (n = 5) and focal segmental glomerulosclerosis (n = 4). Before, at the end of a 90 day course of cyclosporin A, and finally 1 month after stopping cyclosporin A we determined 24 h protein excretion. Measurements of glomerular filtration rate, effective renal plasma flow, fractional clearance rates of albumin and immunoglobulins with different charges and the transglomerular sieving of uncharged dextrans of broad size distribution were used to study the effects of cyclosporin A on renal perfusion and the glomerular filtration barrier. The findings were analysed with a theoretical model of solute transport.
2. Among the different forms of glomerulopathy the response to low-dose cyclosporin A (trough levels 32.0–36.9 ng/ml) varied markedly. In minimal change disease, proteinuria decreased from 9.5 ± 3.1 to 1.3 ± 0.2 g/24 h (mean ± sem, P &lt; 0.01). This response was due to restoration of the charge selectivity of the glomerular barrier. The depressed value of the glomerular permeability coefficient also returned to normal. Glomerular filtration rate, effective renal plasma flow and renal vascular resistance did not change. Proteinuria returned after stopping cyclosporin A, although it did not reach pretreatment levels. In membranous glomerulopathy, proteinuria fell from 9.9 ± 1.5 to 1.8 ± 0.3 g/24 h (P &lt; 0.01). Changes in protein excretion and dextran sieving were compatible with an increase in glomerular permselectivity and a decrease in filtrate flow through the ‘shunt’ pathway. Glomerular filtration rate was maintained, although effective renal plasma flow fell significantly. Proteinuria relapsed after stopping cyclosporin A. In membranoproliferative glomerulonephritis and focal segmental glomerulosclerosis proteinuria did not respond to cyclosporin A, although cyclosporin A exerted important haemodynamic effects.
3. In minimal change disease and membranous glomerulopathy cyclosporin A exerts its beneficial effects on proteinuria through changes in the properties of the glomerular barrier, resulting in increased charge and size selectivity, respectively.
Four-component model for the assessment of body composition in humans: comparison with alternative methods, and evaluation of the density and hydration of fat-free mass
Authors: Fuller N. J. , Jebb S. A. , Laskey M. A. , Coward W. A. , Elia M. 
Published: August 2015

1. Body composition was assessed in 28 healthy subjects (body mass index 20–28 kg/m2) by dual-energy X-ray absorptiometry, deuterium dilution, densitometry, 40K counting and four prediction methods (skinfold thickness, bioelectrical impedance, near-i.r. interactance and body mass index). Three- and four-component models of body composition were constructed from combinations of the reference methods. The results of all methods were compared. Precision was evaluated by analysis of propagation of errors. The density and hydration fraction of the fat-free mass were determined.
2. From the precision of the basic measurements, the propagation of errors for the estimation of fat (± sd) by the four-component model was found to be ± 0.54 kg, by the three-component model, ± 0.49 kg, by deuterium dilution, ± 0.62 kg, and by densitometry, ± 0.78 kg. Precision for the measurement of the density and hydration fraction of fat-free mass was ± 0.0020 kg/l and ± 0.0066, respectively.
3. The agreement between reference methods was generally better than between reference and alternative methods. Dual-energy X-ray absoptiometry predicted three- and four-component model body composition slightly less well than densitometry or deuterium dilution (both of which greatly influence these multi-component models).
4. The hydration fraction of fat-free mass was calculated to be 0.7382 ± 0.0213 (range 0.6941–0.7837) and the density of fat-free mass was 1.1015 ± 0.0073 kg/1 (range 1.0795–1.1110 kg/1), with no significant difference between men and women for either.
5. The results suggest that the three- and four-component models are not compromised by errors arising from individual techniques. Dual-energy X-ray absorptiometry would appear to be a suitable alternative method for the assessment of body composition in these healthy adults. The traditional mean value assumed for density of the fat-free mass in classic densitometry (1.1 kg/l) appears to be appropriate, and the mean hydration fraction was close to values which are generally applied to the fat-free mass (0.72–0.73). Despite concealing considerable inter-individual variation, these mean values may be applied to groups with characteristics similar to those in this study. Finally, with the notable exception of skinfold thickness, bedside prediction methods show poor agreement with both the three- and the four-component models.
Measurement of plasma volume in pregnancy
Authors: Brown Mark A. , Mitar Dina A. , Whitworth Judith A. 
Published: August 2015

1. Determination of the plasma volume in pregnant women is a useful research tool and may become an important clinical measurement. We used three methods to determine plasma volume using Evans Blue dye: (1) the ‘usual’ method, measuring serum absorbance at a wavelength of 610 nm, (2) a two-wavelength method, and (3) precipitation of non-albumin proteins by the addition of polyethyleneglycol before measuring serum absorbance at a wavelength of 620 nm. These were each compared with the standard 125I-human serum albumin method in 20 non-pregnant subjects. Subsequently, the polyethylene glycol method was considered the standard and the three Evans Blue dye methods were compared in 20 pregnant women.
2. In non-pregnant subjects mean plasma volumes did not differ significantly according to the method used. However, the limits of agreement with 125I-human serum albumin method were closest for the polyethyleneglycol method, for both clear and turbid sera.
3. In pregnant women, mean plasma volume values did not differ according to the Evans Blue dye method used, but the limits of agreement were significantly closer with the two-wavelength method than with the ‘usual’ method (P&lt;0.05) largely owing to the effects of turbid sera.
4. These studies demonstrate that considerable error may occur when the Evans Blue dye concentration is determined in turbid sera by the ‘usual’ method. This can be overcome by the use of the two-wavelength method or the polyethyleneglycol method. The most accurate results will be obtained if the latter method is employed routinely to determine plasma volume in pregnant women.