bluuebunny/crossref_metadata_2025 huggingface dataset:
Sulphation of colonic and rectal mucin in inflammatory bowel disease: reduced sulphation of rectal mucus in ulcerative colitis
Authors: Raouf A. H. , Tsai H. H. , Parker N. , Hoffman J. , Walker R. J. , Rhodes Jonathan M.
Published: August 2015

1. Normal colonic mucin is heavily sulphated and this increases its resistance to degradation by bacterial enzymes. Any defect in mucus sulphation could therefore be important in the pathogenesis of ulcerative colitis.

2. Rectal biopsies taken at colonoscopy from patients with ulcerative colitis (n = 9), patients with Crohn's disease (n = 6) and control subjects (n = 16) were cultured for 24 h in the presence of N-[3H]acetyl-glucosamine and [35S]sulphate. Mucin was then extracted and purified, and the ratio of [35S]sulphate to N-[3H]acetyIglucosamine incorporated into pure mucin was assessed.

3. The ratio of [35S]sulphate to N-[3H]acetylglucosamine incorporated into mucin was significantly reduced in rectal biopsies taken from patients with ulcerative colitis (0.463, 0.305–0.703, geometric mean and 95% confidence intervals) compared with control subjects (0.857, 0.959–1.111, P<0.01). In patients with Crohn's disease the reduction in this ratio (0.559, 0.378–0.829) did not quite reach statistical significance (P=0.06). There was no difference between the ratio of [35S]sulphate to N-[3H]acetyl-glucosamine incorporated into mucin in Crohn's disease and that in ulcerative colitis (P = 0.26).

4. In control subjects the ratio of [35S]sulphate to N-[3H]acetylglucosamine incorporated into mucin was higher in the rectal biopsies (0.882, 0.618–1.022) than in their paired proximal colonic biopsies (0.602, 0.421–0.861; P<0.01), but this regional variation was not observed in either ulcerative colitis (rectum: 0.450, 0.262–0.773; right colon: 0.470, 0.321–0.690, P = 0.3) or Crohn's disease (rectum: 0.459, 0.260–0.815; right colon: 0.492, 0.260–0.929, P = 0.8).

5. There was no significant difference in N-[3H]acetylglucosamine incorporation among the three groups (control subjects: 21195, 16611–32695 d.p.m./mg of biopsy protein content; ulcerative colitis: 12108, 7663-21 548 d.p.m./mg of biopsy protein content; Crohn's disease: 14 891, 8620-34 419 d.p.m./mg of biopsy protein content, P = 0.17), suggesting that there is a selective reduction of incorporation of sulphate per mucin side chain.

6. This study demonstrates a reduced ability of the rectal mucosa to sulphate mucin in patients with inflammatory bowel disease.
Inhibition of neutral endopeptidase stimulates renal sodium excretion in patients with chronic renal failure
Authors: Dussaule J. C. , Michel C. , Peraldi M. N. , Lecomte J. M. , Gros C. , Mignon F. , Ardaillou R.
Published: August 2015

1. The acute effects of a single oral dose of sinorphan (100 mg), an inhibitor of neutral endopeptidase, on the plasma atrial natriuretic factor level and the fractional excretion of sodium were examined in 12 patients with severe chronic renal failure who were not on maintenance haemodialysis and who ingested a normal sodium diet. The drug was administered against placebo by a double-blind cross-over protocol.

2. Basal plasma atrial natriuretic factor level and fractional excretion of sodium were high (23.2 ± 3.7 pmol/l and 2.64 ± 0.38%, respectively). Sinorphan inhibited plasma neutral endopeptidase activity by 68–75% 30 min after ingestion. This effect persisted for at least 4 h. There were simultaneously increases in plasma atrial natriuretic factor and cyclic GMP levels to 1.9 and 1.4 times the basal values, respectively. Fractional excretion of sodium increased during the second and third hour periods after ingestion of the drug with a peak of 1.9 times the basal value in the second period. Changes in fractional excretion of sodium were significantly correlated with those in plasma atrial natriuretic factor and cyclic GMP levels. Plasma aldosterone level, creatinine clearance and mean blood pressure were unchanged, whereas plasma renin activity increased slightly. An increase in urinary cyclic GMP excretion was observed in parallel with the increase in plasma cyclic GMP level.

3. The results of the present study indicate that (i) high basal values of plasma atrial natriuretic factor level and fractional excretion of sodium, as observed in patients with chronic renal failure, are associated with marked effects of neutral endopeptidase inhibition; (ii) fractional sodium excretion increases after protection of endogenous atrial natriuretic factor from degradation independently of any initial change in extracellular fluid volume or sodium intake, which suggests that this hormone may play a role in the control of sodium excretion in chronic renal failure.
Regulation of β myosin heavy chain, c-myc and c-fos proto-oncogenes in thyroid hormone-induced hypertrophy of the rat myocardium
Authors: Green N. K. , Gammage M. D. , Franklyn J. A. , Heagerty A. M. , Sheppard M. C.
Published: August 2015

1. In order to investigate the molecular mechanisms determining the hypertrophic response of the ventricular myocardium to thyroid hormone administration, changes in left and right ventricular expression of the c-myc, c-fos and H-ras proto-oncogenes in response to treatment with 3,3′,5-tri-iodothyronine were defined.

2. Adult female Wistar rats were treated with daily subcutaneous injections of 3,3′,5-tri-iodothyronine (50 μg) for 1, 3, 7 or 14 days (n = 6 in each treatment group) and the results from 3,3′,5-tri-iodothyronine-treated animals were compared with those obtained from untreated controls (n = 6). Changes in the weight of the left and right ventricles in response to 3,3′,5-tri-iodothyronine treatment were measured; changes in expression of the c-myc, c-fos and H-ras proto-oncogenes were determined in parallel by measurement of specific messenger RNAs by Northern and dot hybridization, as well as changes in expression of β myosin heavy chain messenger RNA.

3. Treatment with 3,3′,5-tri-iodothyronine resulted in increases in both left and right ventricular weights after 3 days, an effect maintained up to 14 days. Despite an increase in left ventricular weight, levels of β myosin heavy chain, c-myc, c-fos and H-ras mRNAs in the left ventricle were unchanged; in contrast, an increase in right ventricular weight was associated with increased expression of β myosin heavy chain, c-myc and c-fos messenger RNAs.

4. These specific ventricular changes in gene expression, in the face of a hypertrophic response of both ventricles to 3,3′,5-tri-iodothyronine, suggest that the cardiac growth response to thyroid hormones reflects the well-documented secondary haemodynamic influences rather than direct gene regulatory actions of 3,3′,5-tri-iodothyronine at the transcriptional level on the genes studied. Changes in right ventricular proto-oncogene and β myosin heavy chain expression may in turn reflect an increase in right ventricular pressure load.
Coagulation and fibrinolytic systems in type I diabetes: effects of venous occlusion and insulin-induced hypoglycaemia
Authors: Wieczorek Iwona , Pell Alistair C. H. , McIver Brian , MacGregor Ian R. , Ludlam Christopher A. , Frier Brian M.
Published: August 2015

1. The effects of venous occlusion on the coagulation and fibrinolytic systems were investigated in six patients with type 1 (insulin-dependent) diabetes and 11 age- and sex-matched non-diabetic control subjects. The coagulation parameters (fibrinogen, prothrombin time, partial thromboplastin time with kaolin, von Willebrand factor antigen) did not differ between patients and control subjects either before or after 20 min of venous occlusion. No rise was observed in von Willebrand factor antigen after venous occlusion in either group.

2. In the diabetic patients, chronic activation of the fibrinolytic system was found at baseline, which was indicated by a shortened euglobulin lysis time (P < 0.01), increased tissue plasminogen activator activity (P < 0.05) and decreased plasminogen activator inhibitor type 1 antigen level (P < 0.05), when compared with control subjects. In both groups venous occlusion resulted in significant increments in all measurements, except plasminogen activator inhibitor type 1 antigen level. The post-occlusion values did not differ between the two groups, except the plasminogen activator inhibitor type 1 antigen level, which remained significantly lower in the diabetic patients. The mean increments in each parameter did not differ between the two groups.

3. Coagulation and fibrinolysis were assessed in response to acute insulin-induced hypoglycaemia. Von Willebrand factor antigen levels increased significantly in both groups, with no difference in maximal increments. Significant activation of the fibrinolytic system occurred in response to hypoglycaemia, demonstrated by shortened euglobulin lysis time and increased fibrin plate lysis, tissue plasminogen activator antigen level and tissue plasminogen activator activity. The absolute increments were significantly lower in the diabetic group, with an attenuated response of euglobulin lysis time (P < 0.05), tissue plasminogen activator antigen level (P < 0.01) and tissue plasminogen activator activity.

4. Although fibrinolysis was higher in the basal state in the diabetic patients, the attenuated response to hypoglycaemia may indicate the presence of an underlying acquired dysfunction of the vascular endothelium in diabetes. This may be of relevance to the pathogenesis of microvascular disease in type 1 diabetes.
Molecular studies on an ancient gene encoding for carbamoyl-phosphate synthetase
Authors: Schofield J. P.
Published: August 2015

1. Carbamoyl-phosphate synthetase (EC 6.3.5.5.) catalyses the synthesis of carbamoyl phosphate, the immediate precursor of arginine and pyrimidine biosynthesis, and is highly conserved throughout evolution. The large subunit of all carbamoyl-phosphate synthetases sequenced to date comprises two highly homologous halves, the product of a proposed ancestral gene duplication. The sequences of the enzymes of Escherichia coli, Drosophila melanogaster, Saccharomyces cerevisiae, rat and Syrian hamster all have duplications, suggesting that this event occurred in the progenote predating the separation of the major phylae. Until now, only limited data on carbamoyl-phosphate synthetase were available for the primitive eukaryote Dictyostelium discoideum and for the Archaea Methanosarcina barkeri MS. The DNA sequence of the D. discoideum carbamoylphosphate gene and additional sequence for the carbamoyl-phosphate synthetase gene of M. barkeri MS have been determined, and a duplicated structure for both is clearly demonstrated.

2. Genes with ancient duplications provide unique information on their evolution. A study of the intron/exon organization of the rat carbamoylphosphate synthetase I gene and the carbamoylphosphate synthetase hamster II gene in the CAD multi-gene complex shows that at least some of their introns are very old. Evidence is provided that some introns must have been present in the ancestral precursor before its duplication.

3. The human carbamoyl-phosphate synthetase I gene has been isolated and characterized. A human liver cDNA library was constructed and probed for carbamoyl-phosphate synthetase I. A human genomic DNA cosmid library was also probed for the carbamoyl-phosphate synthetase I gene. The cDNA sequence of the human carbamoyl-phosphate synthetase I gene has been determined, and work has been initiated to confirm that at least part of this gene is contained within two cosmids spanning 46 kb. This will enable future studies to be made on mutations in this gene in the rare autosomal recessive deficiency of carbamoyl-phosphate synthetase I.
Effect of residence at altitude on the perception of breathlessness on return to sea level in normal subjects
Authors: Wilson Rachel C. , Oldfield W. L. G. , Jones P. W.
Published: August 2015

1. The effect of residence at altitude on the perception of breathlessness after return to sea level was examined in normal subjects. Breathlessness (Borg scale), minute ventilation, respiratory frequency, tidal volume, ‘oxygen pulse’ (oxygen consumption/heart rate) and the ventilatory equivalent for oxygen (minute ventilation/oxygen consumption) were measured at exercise (cycle-ergometer) during 5 months of training before 4 weeks at 4000 m and during the 6 month period after return to sea level.

2. There was no change in the subjects' pattern of breathing (respiratory frequency and tidal volume) or ‘oxygen pulse’ after the period at altitude (P = 0.0001). The ventilatory equivalent for oxygen was increased at all work rates after the period at altitude (P = 0.02). This ratio was slightly lower after 6 weeks and had returned to normal by 6 months (P = 0.4).

3. During training there was no change in breathlessness score (P = 0.6). On return to sea level, breathlessness score relative to ventilation was reduced (P = 0.0001). This was maintained for at least 6 weeks, but not as long as 6 months.

4. This study has demonstrated that, in normal subjects, the otherwise stable and reproducible relationship between breathlessness and ventilation may be disrupted for several weeks by factors other than lung disease.

5. The mechanism responsible for this is not clear, but the observations are consistent with the hypothesis that prior experience of breathlessness may condition subsequent estimates of breathlessness.
Evidence against a putative role for glucagon as a physiological splanchnic vasodilator in man
Authors: Braatvedt G. D. , Stanners A. , Newrick P. G. , Halliwell M. , Corrall R. J. M.
Published: August 2015

1. Previous studies have suggested that glucagon in supraphysiological doses may mediate postprandial and hypoglycaemia-induced splanchnic vasodilatation in man and experimental animals. There are no reported studies investigating the role of glucagon in doses producing circulating concentrations within the physiological range.

2. Two separate studies were performed. In study 1, superior mesenteric artery blood flow was measured by Doppler ultrasound in six normal subjects during either saline or glucagon infusion at 1, 3 and 6 ng min−1 kg−1, which resulted in circulating glucagon levels within the physiological range. Mean superior mesenteric artery blood flow fell during the 3 and 6 ng min−1kg−1 glucagon infusions (3 ng min−1kg−1: −31.8%, range −20 to −56% of baseline; 6 ng min−1 kg−1: −20.7%, range −8 to −53% of baseline; P < 0.05).

3. In study 2, superior mesenteric artery blood flow was measured during hypoglycaemia induced by an insulin infusion in 12 normal subjects. In six of these subjects the effect of suppression of glucagon release during hypoglycaemia was assessed by preteatment with the somatostatin analogue octreotide (0.8 μg/kg subcutaneously) given 30 min before the insulin infusion.

4. The nadir in blood glucose concentration at the hypoglycaemic reaction was similar in both groups and glucose recovery was complete by 60 min after the hypoglycaemic reaction. Plasma catecholamine concentrations rose in both groups after the hypoglycaemic reaction.

5. Superior mesenteric artery blood flow rose at the hypoglycaemic reaction in both groups despite suppression of glucagon release with octreotide.

6. These data suggest that at physiological concentrations glucagon does not mediate splanchnic vasodilatation in man.
Nocturnal desaturation and serum erythropoietin: A study in patients with chronic obstructive pulmonary disease and in normal subjects
Authors: Fitzpatrick Michael F. , MacKay Tom , Whyte Kenneth F. , Allen Martin , Tam Robert C. , Dore Caroline J. , Henley Michael , Cotes P. Mary , Douglas Neil J.
Published: August 2015

1. To clarify the relationship between nocturnal oxygen desaturation and erythropoietin production in patients with chronic obstructive pulmonary disease, we determined arterial oxygen saturation and serum immunoreactive erythropoietin levels over 24 h in eight patients with chronic obstructive pulmonary disease and in nine normal subjects.

2. In the normal subjects, there was a significant circadian variation in serum erythropoietin levels with the highest mean deviation from the geometric mean at 22.00 hours and the nadir at 05.00 hours.

3. The three patients with chronic obstructive pulmonary disease with the most marked nocturnal desaturation (lowest arterial oxygen saturation <57%) and most marked daytime hypoxaemia (daytime arterial partial pressure of oxygen < 6 kPa) had raised nocturnal serum erythropoietin levels. In two of these patients, the serum erythropoietin level was raised throughout the 24 h and erythrocyte mass was also raised. In the other patient, the serum erythropoietin level was not raised in five daytime samples and erythrocyte mass was normal.

4. The other five patients with chronic obstructive pulmonary disease with less severe nocturnal hypoxaemia (lowest arterial oxygen saturation range 78–86%) had serum erythropoietin levels (range 14–36 m-i.u./ml) which were indistinguishable from normal (range 12–44 m-i.u./ml) and showed circadian changes which were not significantly different (P = 0.35) from those in the normal subjects.

5. Thus, mild nocturnal oxygen desaturation is not associated with elevation of serum erythropoietin levels, whereas daytime hypoxaemia with associated severe nocturnal desaturation is associated with increased serum erythropoietin levels both by day and by night.
Electron paramagnetic resonance spectroscopy of stable free radicals in the liver compared with ultrastructural and functional damage in a rat model of alcohol- and iron-overload
Authors: Butcher Graham P. , Deighton Nigel , Batt Roger M. , Ding Boliang , Haywood Susan , Hoffman John , Jackson Malcolm J. , Symons Martyn C. R. , Rhodes Jonathan M.
Published: August 2015

1. Electron paramagnetic resonance spectroscopy was used to study free-radical signals in freeze-clamped frozen liver tissue from rats after a 1 year period of dietary supplementation with alcohol, iron, or alcohol and iron. In alcohol-fed, iron-fed and alcohol- and iron-fed animals, mild histological damage was seen on light microscopy and evidence of mitochondrial and nuclear injury was identified by electron microscopy.

2. Subcellular fractionation studies showed an increase in the activity of the peroxisomal marker catalase (P <0.01) in alcohol-fed rats compared with controls, but a fall of 82% (P <0.001) in alcohol- and iron-fed animals. The activity of the mitochondrial marker succinate dehydrogenase rose by 7% (not significant) in alcohol-fed animals and by 17% (not significant) in iron-fed animals, but fell by 94% (P <0.001) in alcohol- and iron-fed animals, suggesting serious impairment of mitochondrial function.

3. Iron overload was substantial in the iron-fed animals and there was an excellent correlation between liver iron concentration and iron-derived signals by electron paramagnetic resonance spectroscopy (P <0.001). A clear free-radical signal of g = 2.003–2.005 was detected in all liver samples, but there was no significant difference in the magnitude of this signal in any study group.

4. The absence of any increase in the stable free-radical signal, even in the presence of considerable hepatic damage, does not support the hypothesis that free radicals mediate alcoholic liver disease in this animal model, although the results cannot be taken as proof against this hypothesis.
Noradrenaline Kinetics and Coronary Haemodynamics during Acute β1-Adrenoceptor Blockade in Man
Authors: McCance Alastair J. , Forfar J. Colin
Published: August 2015

1. To investigate the effects of acute β1-adrenoceptor blockade on sympathetic nervous activity, cardiac and whole-body noradrenaline kinetics were determined during intravenous infusions of saline placebo and of metoprolol (10-15 mg plus 150 μg min−1 kg−1) in 10 patients undergoing diagnostic cardiac catheterization, in whom β-adrenoceptor antagonists had been discontinued for 7 days.

2. Coronary haemodynamics were measured in these 10 patients plus two others. Compared with saline placebo, metoprolol administration was associated with decreases in heart rate (68 ± 2 to 59 ± 3 beats/min, P < 0.001) and coronary sinus blood flow (86 ± 8 to 68 ± 6 ml/min, P < 0.001) and an increase in calculated coronary vascular resistance (1.42 ± 0.19 to 1.75 ± 0.22 mmHg min ml−1, P < 0.001). Arterial and femoral venous noradrenaline concentrations, whole-body noradrenaline clearance and whole-body noradrenaline spillover to arterial plasma did not change. In contrast, cardiac noradrenaline spillover (33.7 ± 5.1 to 20.2 ± 4.3 pmol/min, P < 0.05) and cardiac noradrenaline clearance (31 ± 3 to 23 ± 3 ml/min, P < 0.001) were significantly decreased during metoprolol administration.

3. These results may be explained by inhibition of pre-junctional facilitatory β-adrenoceptors, which we hypothesize may be predominantly of the β1-subtype in the heart and of the β2-subtype in the periphery.
Endothelium-Dependent Modulation of Responses to Endothelin-1 in Human Veins
Authors: Haynes William G. , Webb David J.
Published: August 2015

1. We have investigated whether local vascular production of nitric oxide or prostacyclin regulates venoconstriction induced by the endothelium-derived peptide, endothelin-1, in vivo in man.

2. Six healthy subjects received local dorsal hand vein infusion of endothelin-1 for 60 min alone or, on two separate occasions, co-infused with the donator of nitric oxide, glyceryl trinitrate, or the vasodilator prostaglandin, prostacyclin. In further studies, endothelin-l was co-infused with an inhibitor of nitric oxide production, NG-monomethyl-L-arginine, or after oral administration of the irreversible inhibitor of prostaglandin production, acetylsalicylic acid (aspirin).

3. At a low dose (5 pmol/min), endothelin-1 alone caused slowly developing and long-lasting venoconstriction (maximal constriction: 66 ± 4%). Although glyceryl trinitrate partially prevented endothelin-1-induced venoconstriction (maximum: 33 ± 5%), inhibition of nitric oxide production did not affect endothelin-1-induced venoconstriction (maximum: 55 ± 4%).

4. Prostacyclin was more effective at blocking the venoconstriction in response to endothelin-1 than glyceryl trinitrate (maximum: 12 ± 3%), and there was substantial potentiation of endothelin-1-induced venoconstriction after pretreatment with aspirin (maximum: 90 ± 3%).

5. Despite the capacity of nitric oxide to attenuate responses to endothelin-1, NG-monomethyl-L-arginine did not potentiate endothelin-1-induced venoconstriction, suggesting little or no stimulated production of nitric oxide in human veins. However, the potentiation of responses to endothelin-1 by aspirin indicates that endothelial production of prostacyclin attenuates responses to endothelin-1 in human veins in vivo.
Long-Term Insulin Treatment of Vascular Smooth Muscle Cells from Rat Aorta Attenuates the Synergistic Effect of Insulin on Angiotensin II- and Epidermal Growth Factor-Induced DNA Synthesis
Authors: Yon KO , Nettekoven Willy , Christian Roger , Wieczorek Andreas J. , Düsing Rainer , Vetter Hans , Sachinidis Agapios
Published: August 2015

1. in the present study the effects of acute and chronic insulin treatment on growth factor-induced cell growth were investigated in vascular smooth muscle cells. Cell growth was quantified by the incorporation of [3H]thymidine into cell DNA and by determination of total protein.

2. Insulin in a concentration range of 10−9-10−6 mol/l had no effect on cell DNA synthesis. Insulin-like growth factor-1 in a concentration range of 10−9-10−6 mol/l induced a concentration-dependent increase in total cell protein, whereas no changes in DNA synthesis were observed.

3. Acutely, insulin enhanced the mitogenic effect of epidermal growth factor and angiotensin II. Long-term treatment with 10 and 100 ng/ml insulin over 14 weeks was associated with a time-dependent reduction in this potentiating effect of insulin on growth factor-induced DNA synthesis. To evaluate the mechanism of this effect, receptor binding studies were performed with 125I-labelled insulin-like growth factor-1. No difference in the Kd value (2.1 nmol/l) for insulin-like growth factor-1 was found between untreated and chronically insulin-treated cells, whereas the maximal number of binding sites decreased from 5.9 × 104 (untreated cells) to 4.7 × 104 (10 ng/ml) and to 4.3 × 104 (100 ng/ml) binding sites/cell in chronically insulin-treated cells.

4. We conclude that insulin acutely enhances the mitogenic effect of various growth factors such as epidermal growth factor and angiotensin II on vascular smooth muscle cells. Long-term insulin treatment reduced the number of receptor binding sites for insulin-like growth factor-1. This may contribute to the reduced response of cells to growth stimulation after chronic in contrast with acute insulin treatment.
Treatment of Anaemia in Haemodialysis Patients with Erythropoietin: Long-Term Effects on Exercise Capacity
Authors: Báaráany Peter , Freyschuss Ulla , Pettersson Erna , Bergström Jonas
Published: August 2015

1. The effects of correcting anaemia on exercise capacity were evaluated in 21 haemodialysis patients (aged 39 ± 12 years) before starting treatment with recombinant human erythropoietin (Hb concentration, 73 ± 10 g/l; total Hb, 59 ± 12% of expected), after correction of the anaemia to a Hb concentration of 108 ± 7 g/l and a total Hb 82 ± 10% of expected, and in 13 of the patients after 12 months on maintenance recombinant human erythropoietin treatment (Hb concentration 104 ± 14 g/l, total Hb 79 ± 17% of expected). Fifteen healthy subjects (aged 41 ± 9 years), who took no regular exercise, constituted the control group. Maximal exercise capacity was determined on a bicycle ergometer. Oxygen uptake, respiratory quotient, blood lactate concentration, heart rate and blood pressure were measured at rest and at maximal workload.

2. After 6 ± 3 months on recombinant human erythropoietin, maximal exercise capacity increased from 108 ± 27 W to 130 ± 36 W (P < 0.001) and the maximal oxygen uptake increased from 1.24 ± 0.39 litres/min to 1.50 ± 0.45 litres/min (P < 0.001). No significant changes in respiratory quotient (1.16 ± 0.13 versus 1.18 ± 0.13) and blood lactate concentration (4.0 ± 1.8 versus 3.6 ± 1.1 mmol/l) at maximal workload were observed, but the blood lactate concentration in the patients was significantly lower than that in the control subjects (6.7 ± 2.3 mmol/l, P < 0.01). After the correction of anaemia, the aerobic power was still 38% lower in the patients than in the control subjects and 17% lower than the reference values.

3. After 12 months on maintenance recombinant human erythropoietin treatment (17 ± 3 months from the start of the study), no further significant changes were observed in maximal exercise capacity (before start, 112 ± 31 W, 6 ± 3 months, 134 ± 42 W, 17 ± 3 months, 134 ± 50 W), maximal oxygen uptake (before start, 1.33 ± 0.45 litres/min; 6 ± 3 months, 1.59 ± 0.54 litres/min; 17 ± 3 months, 1.75 ± 0.78 litres/min) or blood lactate concentration (before start, 4.4 ± 1.9 mmol/l; 6 ± 3 months, 4.0 ± 1.0 mmol/l; 17 ± 3 months, 4.7 ± 2.0 mmol/l).

4. Thus, in haemodialysis patients the improvement in maximal aerobic power after the correction of anaemia persists without marked changes during long-term treatment with recombinant human erythropoietin. We did not observe any effects on exercise capacity that could be attributed to a spontaneous increase in physical activity after treatment of anaemia.
Sialic Acids in Human Gastric Aspirates: Detection of 9-O-Lactyl- and 9-O-Acetyl-N-Acetylneuraminic Acids and a Decrease in Total Sialic Acid Concentration with Age
Authors: Corfield A. P. , Wagner S. A. , Safe A. , Mountford R. A. , Clamp J. R. , Kamerling J. P. , Vliegenthart J. F. G. , Schauer R.
Published: August 2015

1. The total sialic acid content of human gastric aspirates was measured using a colorimetric assay. Care was taken to optimize the assay and to eliminate interference.

2. The sialic acid content of gastric aspirates collected under resting conditions from 77 patients with non-ulcer dyspepsia was found to decrease with age from >100 μg/ml at 25 years and younger to <20 μg/ml above 70 years of age.

3. Analysis of the sialic acids by gas chromatography, mass spectrometry and thin-layer chromatography showed the presence of N-acetylneuraminic acid and two O-acylated derivatives, 9-O-acetyl- and 9-O-lactyl-N-acetylneuraminic acids. These forms were predominantly glycosidically bound.

4. Thin-layer chromatographic analysis of individual aspirate samples showed that the O-acetylated sialic acids were present in all samples, with a maximum of 25% and a minimum of 5% of the total sialic acids.
Glycated Albumin in Serum and Dialysate of Patients on Continuous Ambulatory Peritoneal Dialysis
Authors: Lamb E. , Cattell W. R. , Dawnay A.
Published: August 2015

1. Chronic use of hyperosmolar glucose solutions in continuous ambulatory peritoneal dialysis may cause glycation of peritoneal structural proteins which could contribute to membrane dysfunction and ultrafiltration failure. To determine whether glycation can occur in the environment of the dialysate, we have carried out studies using albumin as a model protein.

2. Glycated albumin was measured in the serum and dialysate of 46 patients on continuous ambulatory peritoneal dialysis (31 non-diabetic patients, 15 diabetic patients). Dialysate and serum glycated albumin (ranges 1.0-12.7% and 0.9-10.2%, respectively) were related to each other (r = 0.988, P <0.001), but dialysate glycated albumin was significantly higher than serum glycated albumin (P <0.0001), with the dialysate to serum glycated albumin ratio being greater than unity in 76% of patients (mean ratio 1.14). This implies either preferential transfer of glycated albumin across the peritoneal membrane or intraperitoneal glycation during the dwell period.

3. In vitro, significant glycation occurred in dialysate during a 6 h incubation period (P <0.01) at a rate related to the glucose concentration in the dialysate (rs = 0.63, P <0.05). The glycation rate was not significantly affected (P = 0.05) by factors other than the glucose concentration.

4. Our results demonstrate that protein glycation occurs within the peritoneum during continuous ambulatory peritoneal dialysis. Further studies are required to establish the relationship of glycation of structural proteins in the peritoneal membrane to membrane function.
Clenbuterol, a β-Adrenoceptor Agonist, Increases Relative Muscle Strength in Orthopaedic Patients
Authors: Maltin C. A. , Delday M. I. , Watson J. S. , Heys S. D. , Nevison I. M. , Ritchie I. K. , Gibson P. H.
Published: August 2015

1. The sympathomimetic agent clenbuterol has a muscle-specific anabolic effect in normal and wasted muscles from animals. This trial was designed to examine the effect of the drug on the recovery of muscle strength and area after open medial meniscectomy.

2. A double-blind, completely randomized, placebo-controlled study was carried out on 20 healthy male patients. Muscle strength and cross-sectional area were determined before and after surgery. Patients were treated with drug or placebo for 4 weeks postoperatively and there was a 2 week washout period.

3. The results suggest that, in the operated leg, clenbuterol treatment is associated with a more rapid rehabilitation of strength in knee extensor muscles; in the unoperated leg, knee extensor strength increased above the initial values after 6 weeks (P = 0.01). However, in terms of absolute strength the differences were not significant between the two groups.

4. It is concluded that the data lend support to the proposition that clenbuterol has therapeutic potential in the treatment of muscle-wasting conditions.
Abnormal Urate Transport in Erythrocytes of Patients with Idiopathic Calcium Nephrolithiasis: A Possible Link with Hyperuricosuria
Authors: Gambaro Giovanni , Vincenti Massimo , Marchini Francesco , D'Angelo Angela , Baggio Bruno
Published: August 2015

1. The demonstration of an inheritable anomaly of erythrocyte oxalate transport in ‘primary’ calcium nephrolithiasis suggested that this disease might be a generalized metabolic disorder characterized by a defect in cellular anion transport.

2. To determine whether this anomaly is restricted to oxalate alone, we studied erythrocyte transmembrane urate self-exchange in calcium-oxalate renal stone formers in whom urinary excretion of uric acid is frequently increased.

3. Abnormal urate self-exchange was found in 30% of the patients. The urate self-exchange rate constant was correlated with 24 h urinary excretion of uric acid; the erythrocyte anomaly was also associated with the frequency of hyperuricosuria and a more intense disease activity. Transmembrane urate self-exchange was inhibited by stilbene and heparan sulphate. Morphazinamide administration did not reduce urinary urate excretion in patients with abnormal urate erythrocyte self-exchange.

4. These findings suggest that hyperuricosuria during calcium-oxalate renal stone disease might be due to a cellular defect in urate transport, and further support the hypothesis that idiopathic nephrolithiasis is a metabolic disorder characterized by a defect in cellular anion transport.
Diffusion of Polyethylene Glycol-400 across Lipid Barriers in Vitro
Authors: Iqbal T. H. , Lewis K. O. , Cooper B. T.
Published: August 2015

1. Polyethylene glycol has been used extensively as a probe to measure passive small-intestinal permeability in viro. However, there has been some uncertainty as to its suitability for use as an indicator of the permeation of water-soluble molecules across the intestinal wall because it seems to traverse the mucosa in much greater quantities than sugar molecules of equivalent Mr.

2. We have measured the permeation of polyethylene glycol-400 and lactulose from aqueous solution across pure lipid solvents in vitro. We found considerable transport of polyethylene glycol-400 across chloroform (1.03 g h−1 m−2) but no movement across petroleum ether.

3. However, in a separate experiment in which phospholipid (egg lecithin) was dissolved in the petroleum ether, permeation of polyethylene glycol-400 did occur (0.13 g h−1 m2), implying interaction of polyethylene glycol-400 with the phospholipid. No permeation of lactulose was seen in any of the experiments.

4. Our results suggest that, because of its interaction with lipid solvents, polyethylene glycol-400 is unsuitable as a probe to measure passive intestinal permeability in vivo.
Isolation of Human Cardiac Endothelin Receptors by a Peptide-Receptor Mobility Shift Assay
Authors: Persidis A. , Harcombe A. A. , Davenport A. P. , Kuc R. E. , Plumpton C. , Weissberg P. L.
Published: August 2015

1. A peptide-protein mobility shift assay has been developed, using native polyacrylamide-gel electrophoresis, that enables the isolation of de-natured receptor proteins from small amounts of human cardiac tissue.

2. Radiolabeled endothelin-1 and related peptides were used to identify and isolate endothelin receptors from partially purified membrane extracts of human atrial tissue.

3. Binding analysis using radiolabelled endothelin-1 gave an equilibrium dissociation constant (Kd) of 2 nmol/l, similar to results from binding experiments conducted directly on tissue.

4. Peptide-receptor complexes were electroeluted from native gels and dissociated. Receptor material was characterized by dot-immunobinding analysis of eluates using an antibody raised against a predicted human endothelin receptor sequence.
Angiopeptin Inhibition of Myointimal Hyperplasia after Balloon Angioplasty of Large Arteries in Hypercholesterolaemic Rabbits
Authors: Howell Marcus H. , Adams Michael M. , Wolfe Mary S. , Foegh Marie L. , Ramwell Peter W.
Published: August 2015

1. Currently, a wide range of drugs is being evaluated for the ability to prevent the restenosis which frequently accompanies percutaneous transluminal coronary angioplasty. Patients undergoing angioplasty are generally hypercholesterolaemic and therefore the possibility that plasma lipids may compromise the efficacy of anti-restenotic drugs must be assessed. A promising drug in several clinical trials for the prevention of restenosis is angiopeptin, an octapeptide analogue of somatostatin that possesses a highly lipophilic terminal.

2. The effect of angiopeptin on myointimal hyperplasia was studied in a rabbit model of arterial balloon catheter injury where the rabbits were made hypercholesterolaemic by a 0.5% cholesterol diet. The degree of subsequent myointimal thickening was measured by morphometry.

3. Angiopeptin (20 μg day−1 kg−1) significantly inhibited myointimal thickening by an average of 47% in the infrarenal aorta and both the common and external iliac arteries in the presence of elevated plasma lipids concentrations. Low dose angiopeptin (2 μg day−1 kg−1) significantly inhibited myointimal thickening in the external iliac artery but not in the other two vessels.

4. Angiopeptin treatment (20 μg day−1 kg−1) did not significantly modify the plasma cholesterol, very-low-density lipoprotein, intermediate-sized low-density lipoprotein, low-density lipoprotein and high-density lipoprotein concentrations that were elevated by the 0.5% cholesterol diet.

5. We conclude that the inhibitory effect of angiopeptin is largely unaffected by elevated plasma lipid concentrations and that this drug did not modify plasma lipid concentrations in rabbits.
Independent, Marked Associations of Alleles of the Insulin Receptor and Dipeptidyl Carboxypeptidase-1 Genes with Essential Hypertension
Authors: Morris Brian J. , Zee Robert Y. L. , Ying Li-Hua , Griffiths Lyn R.
Published: August 2015

1. There is evidence to suggest that essential hypertension is a polygenic disorder and that it arises from yet-to-be-identified predisposing variants of certain genes that influence blood pressure. The cloning of various hormone, enzyme, adrenoceptor and hormone receptor genes whose products are involved in blood pressure control and the identification of polymorphisms of these has permitted us to test their genetic association with hypertension.

2. Cross-sectional analyses of a number of candidate gene markers were performed in hypertensive and normotensive subjects who were selected on the basis of both parents being either hypertensive or normotensive, respectively, and the difference in total alleles on all chromosomes for each polymorphism between the hypertensive and normotensive groups was tested by χ2 analysis with one degree of freedom.

3. A marked association was observed between hypertension and insertion alleles of polymorphisms of the insulin receptor gene (INSR) (P <0.0040) and the dipeptidyl carboxypeptidase-1 (angiotensin I-converting enzyme; kininase II) gene (DCP1) (P <0.0018). No association with hypertension was evident, however, for polymorphisms of the growth hormone, low-density lipoprotein receptor, renal kalli-krein, α2- and β1-adrenoreceptor, atrial natriuretic factor and insulin genes.

4. All but one of the hypertensive subjects had at least one of the hypertension-associated alleles, and although subjects homozygous for both were three times more frequent in the hypertensive group, examination of the nine possible genotypes suggested that the INSR and DCP1 alleles are independent markers for hypertension.

5. The present results suggest that genetic variant(s) in close linkage disequilibrium with polymorphisms at INSR and DCP1 may be involved in part in the aetiology of essential hypertension.
Glutathione Peroxidase Activity and Metabolism of Arachidonic Acid in Peripheral Blood Mononuclear Cells from Elderly Subjects
Authors: Meskini N. , Nemoz G. , Chapuy P. , Haond P. , Pageaux J. F. , Vericel E. , Lagarde M. , Prigent A. F.
Published: August 2015

1. Since ageing has been associated with a decrease in both immune responses and antioxidant defences, this study was undertaken to compare the glutathione peroxidase activity in peripheral blood mononuclear cells of healthy elderly and young donors. The mean value of glutathione peroxidase activity was significantly lower in the aged group (−36%) than that observed in the young control group (n = 10).

2. This defect was accompanied by a marked increase (+106%) in the oxygenated metabolism of endogenous arachidonic acid by lipoxygenases as judged by the radiolabel associated with hydroxyeicosatetraenoic acids in [3H]arachidonic acid-prelabelled peripheral blood mononuclear cells, whereas the cyclo-oxygenase activity, estimated by the radiolabel associated with thromboxane B2, was not significantly altered.

3. Upon stimulation by the mitogenic lectin concanavalin A, the radioactivity associated with total eicosanoids (free arachidonic acid plus hydroxyeicosatetraenoic acids plus thromboxane B2) was significantly increased over basal levels in the peripheral blood mononuclear cells of both the elderly and the control groups. However, the mitogen-induced increase was lower in the elderly group (+48%) than in the control group (+131%). Upon concanavalin A stimulation, the radioactivity of hydroxyeicosatetraenoic acids was increased by only 96% in peripheral blood mononuclear cells from the elderly group compared with 350% in control cells. Similarly, the radioactivity associated with thromboxane B2 was increased by only 82% in peripheral blood mononuclear cells from the elderly group compared with 218% in control cells.

4. Reverse phase h.p.l.c. of the hydroxyeicosatetraenoic acids showed that, in unstimulated peripheral blood mononuclear cells, the 12-hydroxyeicosatetra-enoic acid level tended to be higher in the elderly group than in the control group, which might be indicative of an hyperactivity of the contaminating platelets in peripheral blood mononuclear cells from elderly subjects. However, in stimulated cells, the concanavalin A-induced increase in 12-hydroxyeico-satetraenoic acid proved to be lower in the elderly group (+ 283%) than in the control group (+ 814%). 5. Furthermore, the concanavalin A-induced release of arachidonic acid from the phosphoinositide pool was also decreased in the elderly group as compared with the control group. These results suggest that the major defect of arachidonic acid metabolism in peripheral blood mononuclear cells from elderly subjects might be located at the level of its mitogen-induced liberation known to occur during the early steps of lymphocyte activation. An eventual implication of the lowered glutathione peroxidase activity in the observed abnormalities of arachidonic acid metabolism in cells from aged subjects is discussed.
Comparison between Continuous and Discrete Measurements of Breathlessness during Exercise in Normal Subjects Using a Visual Analogue Scale
Authors: Harty Helen R. , Heywood Peter , Adams Lewis
Published: August 2015

1. Visual analogue scaling of breathlessness made at discrete intervals during ventilatory stimulation tests can provide useful information about the intensity of this sensation. The aim of the present study was to investigate the use of continuous visual analogue scaling as a means of improving the temporal resolution of this measurement.

2. Six normal naive subjects scaled breathlessness using a visual analogue scale, during steady-state exercise. Further changes in this sensation were induced by either sustained hypercapnia or acute hypoxia; these responses were assessed either continuously or at discrete 30 s intervals and the two scaling methods were compared.

3. The continuous method of assessing breathlessness compared favourably with that of the more established discrete method, providing reproducible measurements in repeated tests equivalent in intensity to those obtained every 30 s.

4. Transient changes in the sensation of breathlessness produced by acute episodes of hypoxia were identified using the continuous scaling method but not with discrete scaling.

5. The continuous method of scaling breathlessness should aid the investigation of the neurophysiological basis of this sensation by allowing temporal relationships between changes in respiratory variables and the sensory consequences to be more carefully defined.
Genetic Variation Associated with Differences in the Response of Plasma Apolipoprotein B Levels to Dietary Fibre
Authors: Hegele Robert A. , Zahariadis George , Jenkins Alexandra L. , Connelly Philip W. , Kashtan Hanoch , Stern Hartley , Bruce Robert , Jenkins David J. A.
Published: August 2015

1. We hypothesized that differences within genes whose protein products are involved in apolipoprotein B metabolism could influence the response of plasma apolipoprotein B-containing lipoprotein concentrations to increases in dietary fibre.

2. We studied 67 subjects (43 men and 24 women) who had taken part in parallel 2 week metabolic dietary studies involving either wheat bran or oat bran supplementation. Fasting blood lipid, lipoprotein and apolipoprotein concentrations were measured at the start and end of the 2 week metabolic period. Genotypes were determined using DNA markers for the low-density lipoprotein receptor, apolipoprotein B, apolipoprotein CIII and hepatic lipase gene loci.

3. Reductions in plasma concentrations of apolipoprotein B were significantly different depending on genotype determined with a low-density lipoprotein receptor DNA marker (P = 0.03). There was no significant variation in the reduction of plasma total cholesterol, low-density lipoprotein cholesterol or apolipoprotein B concentrations for alleles of other genes tested.

4. Thus, genetic variability is associated with inter-individual differences in the fibre-related reduction in plasma apolipoprotein B and apolipoprotein B-containing lipoprotein concentrations. Implementation of current dietary recommendations to reduce plasma lipoprotein levels with fibre may have variable effects in different individuals in part because of structural differences in candidate genes whose products are involved in lipoprotein metabolism.
Ionized and Total Magnesium Levels in Cyclosporin-Treated Renal Transplant Recipients: Relationship with Cholesterol and Cyclosporin Levels
Authors: Markell M. S. , Altura B. T. , Barbour R. L. , Altura B. M.
Published: August 2015

1. Ionized magnesium, measured using a newly developed ion-selective electrode, total magnesium, and ionized and total calcium were evaluated in 39 stable, long-term, cyclosporin-treated renal transplant recipients and compared with those of age-matched, non-transplanted control subjects. Total cholesterol, cyclosporin trough level, serum creatinine, time after-transplant and the ratio of ionized calcium to ionized magnesium were also measured in renal transplant recipients and the relationships between these variables and ionized and total magnesium were evaluated.

2. Renal transplant recipients exhibited marked deficits in ionized magnesium, with a mean value of 0.54 ±0.01 mmol/l as compared with 0.61 ± 0.006 mmol/l for normal control subjects (P ≦ 0.05), with a more moderate deficit in total magnesium. Values for ionized and total calcium did not differ. By stepwise linear multiple regression analysis, ionized magnesium was significantly related to cyclosporin trough level and total cholesterol but not to serum creatinine, time after transplant or the dose of cyclosporin. Ionized magnesium correlated inversely with cyclosporin trough level and directly with total cholesterol. The ratio of ionized calcium to ionized magnesium was elevated in renal transplant recipients when compared with control subjects and correlated positively with the cyclosporin trough level.

3. Deficits in ionized magnesium are common during the late post-transplant period in cyclosporin-treated renal transplant recipients. Ionized magnesium may be a more sensitive clinical parameter than total magnesium in this population, in whom total magnesium may be only mildly decreased in the setting of a severe deficit in ionized magnesium.

4. Ionized magnesium correlates with the cyclosporin level. Renal transplant recipients with high cyclosporin levels demonstrate the most severe deficits in ionized magnesium, and this finding could contribute to cyclosporin-induced hypertension and nephrotoxicity. The direct correlation between ionized magnesium and total cholesterol may result from a ‘masked magnesium deficiency’, as has been suggested in animal models, and requires further study. 5. Accelerated atherosclerosis observed after renal transplantation may relate to alterations in ionized magnesium and elevated ratios of ionized calcium to ionized magnesium, which are associated with atherogenesis in other models.