bluuebunny/crossref_metadata_2025 huggingface dataset:
Human cardiovascular variability, baroreflex and hormonal adaptations to a blood donation
Authors: FORTRAT Jacques-Olivier , NASR Olivier , DUVAREILLE Monique , GHARIB Claude
Published: August 2015

1.We studied cardiovascular variability, baroreflex and blood volume regulating hormones to determine the relative roles of autonomic regulation and hormones during blood donation.

2.The sympathetic response was studied by measuring the R–R interval and systolic blood pressure variability using coarse graining spectral analysis in eight blood donors. Beat-by-beat R–R intervals and blood pressure were recorded for 20 ;min before and 5 ;min after a whole-blood donation of 480±10 ;ml (about 7 ;ml/kg of blood volume, over 4 ;min). Plasma catecholamines, vasopressin, atrial natriuretic peptide, endothelin, active renin, osmolality, Na+, K+, haemoglobin and haematocrit were measured just before and after blood withdrawal.

3.Blood donation led to increases in the plasma catecholamines (adrenaline, 21±2 versus 35±3 ;pg/ml; noradrenaline, 229±26 versus 323±37 ;pg/ml; dopamine, 34±3 versus 66±9 ;pg/ml) and in systolic blood pressure (130±6 versus 140±5 ;mmHg). These changes were independent of ionic or slow endocrine mechanisms. Heart rate, cardiovascular variability and the spontaneous baroreflex sensitivity did not change despite the increase in blood pressure and catecholamines. Thus the peripheral vascular control was probably involved.

4.We conclude that the absence of any change in heart rate usually observed during non-hypotensive hypovolaemic stress is probably due to the sympathetic activation being counterbalanced by the high supine vagal tone at the heart and not to the heterogeneous nature of the sympathetic neural response or to changes in sympathetic and parasympathetic activity without any change in autonomic balance.
Fractal dimension and approximate entropy of heart period and heart rate: awake versus sleep differences and methodological issues
Authors: YERAGANI Vikram K. , SOBOLEWSKI E. , JAMPALA V. C. , KAY Jerald , YERAGANI Suneetha , IGEL Gina
Published: August 2015

1.Investigations that assess cardiac autonomic function include non-linear techniques such as fractal dimension and approximate entropy in addition to the common time and frequency domain measures of both heart period and heart rate. This article evaluates the differences in using heart rate versus heart period to estimate fractal dimensions and approximate entropies of these time series.

2.Twenty-four-hour ECG was recorded in 23 normal subjects using Holter records. Time series of heart rate and heart period were analysed using fractal dimensions, approximate entropies and spectral analysis for the quantification of absolute and relative heart period variability in bands of ultra low (< 0.0033 ;Hz), very low (0.0033–0.04 ;Hz), low (0.04–0.15 ;Hz) and high (0.15–0.5 ;Hz) frequency.

3.Linear detrending of the time series did not significantly change the fractal dimension or approximate entropy values. We found significant differences in the analyses using heart rate versus heart period between waking up and sleep conditions for fractal dimensions, approximate entropies and absolute spectral powers, especially for the power in the band of 0.0033–0.5 ;Hz. Log transformation of the data revealed identical fractal dimension values for both heart rate and heart period. Mean heart period correlated significantly better with fractal dimensions and approximate entropies of heart period than did corresponding heart rate measures.

4.Studies using heart period measures should take the effect of mean heart period into account even for the analyses of fractal dimension and approximate entropy. As the sleep–awake differences in fractal dimensions and approximate entropies are different between heart rate and heart period, the results should be interpreted accordingly.
Glycoxidation, and protein and DNA oxidation in patients with diabetes mellitus
Authors: KRAPFENBAUER K. , BIRNBACHER R. , VIERHAPPER H. , HERKNER K. , KAMPEL D. , LUBEC G.
Published: August 2015

1.The role of oxidative stress in the pathogenesis of the diabetic state is being investigated extensively. Although oxidative stress has been reported in terms of glycoxidation, protein oxidation and DNA oxidation in diabetes mellitus, oxidation parameters have not been determined in parallel on the same study population.

2.We studied 24 patients with diabetes mellitus (14 patients with Type I diabetes with a mean age of 62.3±6.3 years and 10 patients with Type II diabetes aged 67.3±5.9 years) and compared them with age-matched non-diabetic controls. Urinary o-tyrosine, 8-hydroxy-2′-deoxyguanosine and pentosidine measurements by HPLC were made on two occasions (t1 and t2).

3.A clear statistical difference was found between diabetic patients and controls at t1 or t2 for 8-hydroxy-2′-deoxyguanosine and pentosidine, but not for o-tyrosine. No significant correlations were found between clinical and other laboratory parameters except high-density lipoprotein and uric acid. We revealed significantly increased glycoxidation and DNA oxidation in patients with Type I and Type II diabetes, but protein oxidation was not different from controls.

4.The finding of increased glycoxidation reflects increased oxidation of the carbohydrate moiety, whereas the increased levels of oxidized DNA may also be interpreted as due to increased DNA repair. The increased 8-hydroxy-2′-deoxyguanosine does not indicate the generation of an individual active oxygen species, but DNA could have been oxidized simply by alkenals from lipid peroxidation, as e.g. malondialdehyde. As no difference in protein oxidation (i.e. o-tyrosine) between diabetics and controls could be revealed, the oxidation of DNA by hydroxyl radical attack is unlikely, as o-tyrosine was proposed as a marker for hydroxyl radical attack. Therefore, the message is that increased glycoxidation can be confirmed, protein oxidation does not appear to take place and increased DNA oxidation is still not proven, as increased 8-hydroxy-2′-deoxyguanosine may simply reflect repair.
Protective agents used as additives in University of Wisconsin solution to promote protection against ischaemia–reperfusion injury in rat lung
Authors: CHIANG Chi-Huei , WU Kerry , YU Cheng-Ping , PERNG Wann-Cherng , YAN Horng-Chin , WU Chin-Pyng , CHANG Deh-Ming , HSU Kang
Published: August 2015

1.An intervention to reduce ischaemia–reperfusion lung injury will be an important advance in transplant medicine. Although the mechanisms associated with producing ischaemia–reperfusion endothelial injury have not been completely elucidated, many of the injury mediators have been studied in detail. While no single pharmacological therapy is likely to be totally effective in eliminating this complex injury, we have developed a mixture of agents that are known to block pathways involved in producing ischaemia–reperfusion-associated lung vascular injury.

2.The present study modified University of Wisconsin solution (UW) by adding one of the protective agents prostaglandin E1 (PGE1), dexamethasone (Dex) or dibutyryl cAMP (Bt2-cAMP), or a combination of these, to the perfusate of rat lungs exposed to 4 ;h of cold ischaemia followed by 1 ;h of reperfusion. Nine modified UW solutions were studied: (1) UW+Dex, (2) UW+PGE1, (3) UW+Bt2-cAMP, (4) UW+Dex×3, (5) UW+PGE1×3, (6) UW+Bt2-cAMP×3, (7) UW+Dex+PGE1, (8) UW+Dex+Bt2-cAMP, (9) UW+PGE1+Bt2-cAMP. These solutions were utilized in individual experiments to assess haemodynamic changes, lung weight gain, the capillary filtration coefficient (Kfc) and pathology in all lungs.

3.The results indicate that lung weight gain and Kfc values were significantly lower than with UW alone in groups 1, 2 and 3, which contained only one additional protective agent. In groups 4, 5 and 6, which contain three times the concentration of each protective agent, both Kfc and lung weight gain were similar to those measured in groups 1, 2 and 3, i.e. lungs were protected but the protection was not dose dependent. In groups 7, 8 and 9, which contained two protective agents, lung weight gain and Kfc were greatly reduced compared with UW alone. Histopathological studies showed similar decreases in the injury profiles of lungs.

4.Although UW contains several antioxidant protective agents such as allopurinol and glutathione, it did not provide effective protection in our ischaemia–reperfusion lung injury model. UW modified with an additive of PGE1, Dex or Bt2-cAMP attenuated ischaemia–reperfusion injury. Furthermore, UW containing two of these protective agents augmented the protection. Among the modified solutions, it appears that UW+PGE1+Bt2-cAMP protects the lungs to a greater extent than all other solutions used in our study. We suggest that preservation solutions containing PGE1-Bt2-cAMP will provide additional protective effects to organs stored for transplantation.
Studies in vivo of ω-gliadins in gluten sensitivity (coeliac sprue disease)
Authors: ENSARI Arzu , MARSH Michael N. , MORIARTY Kieran J. , MOORE Carol. M. , FIDO Roger J. , TATHAM Arthur S.
Published: August 2015

1.Highly purified ω-gliadins from wheat were used to challenge gluten-sensitized individuals. Characteristic responses by mucosal CD3+ and γδ+ lymphocytes were demonstrated. Each lymphocyte subset showed an increase within 8–12 ;h post-challenge, indicating a specific response by the rectal mucosa to this gliadin species.

2.Available sequence data for the ω-gliadins and homologous proteins from barley and rye indicate a common repeating octapeptide motif (consensus PQQPFPQQ). The results indicate, therefore, that the octapeptide repeat, or a contained sequence such as PQQP, plays an important role in the mucosal immunopathology of gluten sensitivity.
Administration of albumin to patients with sepsis syndrome: a possible beneficial role in plasma thiol repletion
Authors: QUINLAN Gregory J. , MARGARSON Michael P. , MUMBY Sharon , EVANS Timothy W. , GUTTERIDGE John M. C.
Published: August 2015

1.Albumin is often administered intravenously to critically ill patients as a volume expander, to combat hypoalbuminaemia, and to decrease hyperbilirubinaemia. There is, however, an ongoing debate concerning the therapeutic benefit of the former which is an expensive form of treatment.

2.Albumin has several biological functions, in particular as a ligand binder. It also acts as an extracellular transition metal ion-binding and radical-scavenging antioxidant. These functions are influenced by the presence of an exposed thiol group (cys 34) on the surface of the albumin molecule.

3.The ability of infused albumin to influence the plasma thiol pool, and hence antioxidant potential, was investigated in patients with sepsis syndrome.

4.Plasma thiol levels rose rapidly after albumin infusion and remained elevated even after plasma albumin levels had declined significantly, due to interstitial leakage. Data are suggestive of some form of thiol exchange in the plasma of these patients between albumin and molecules containing oxidized thiol groups.

5.Administration of albumin to patients with sepsis syndrome leads to a sustained increase in plasma thiols. Thiols have several important antioxidant functions, and thiol repletion in these patients, who are known to suffer from oxidative stress, may have beneficial antioxidant effects. Antioxidant repletion may represent an important facet of clinically administered albumin.
Cytotoxic T-lymphocytes against malaria and tuberculosis: from natural immunity to vaccine design
Authors: LALVANI Ajit , HILL Adrian V. S.
Published: August 2015

1. Mycobacterium tuberculosis and the liver stage of Plasmodium falciparum are intracellular pathogens which are potentially susceptible to cytotoxic T-lymphocytes, a crucial component of the protective immune response to viral infections. Evidence from animal models points to a protective role for cytotoxic T-lymphocytes against M. tuberculosis and P. falciparum, but cytotoxic T-lymphocytes specific for these pathogens have been difficult to identify in man.

2.Using a reverse immunogenetic approach, candidate epitopes from selected antigens of P. falciparum and M. tuberculosis were used to detect peptide-specific cytotoxic T-lymphocyte responses in individuals exposed to these pathogens. Cytotoxic T-lymphocyte activity was detected by the 51Cr release cytotoxicity assay and a sensitive ELISPOT assay for single-cell interferon-γ release.

3.In naturally exposed, partially immune Africans in The Gambia, eight largely conserved cytotoxic T-lymphocyte epitopes in P. falciparum, restricted by several different HLA class I alleles, were identified. Several epitopes were also recognized in Tanzanians and cytotoxic T-lymphocytes recognized endogenously processed antigen.

4.In tuberculosis patients with HLA-B52, a CD8+ cytotoxic T-lymphocyte epitope was identified in ESAT-6, a secreted antigen specific for M. tuberculosis complex but absent in BCG. Cytotoxic T-lymphocytes exhibited HLA-B52-restricted peptide-specific interferon-γ release and lytic activity and recognized endogenously processed antigen.

5.These studies demonstrate that CD8+ cytotoxic T-lymphocytes specific for mycobacterial and protozoal antigens are induced during natural infections in humans. The identification of these T-cells endorses current strategies to develop cytotoxic T-lymphocyte-inducing vaccines against P. falciparum and M. tuberculosis and highlights candidate antigens for inclusion in subunit vaccines.
Aminoguanidine ameliorates splanchnic hyposensitivity to glypressin in a haemorrhage-transfused rat model of portal hypertension
Authors: CHU Chi-Jen , LEE Fa-Yauh , WANG Sun-Sang , CHANG Full-Young , LIN Han-Chieh , HOU Ming-Chih , WU Shwu-Ling , TAI Chung-Ching , CHAN Che-Chang , LEE Shou-Dong
Published: August 2015

1.Hyposensitivity to vasopressin is a well-documented phenomenon in animals with portal hypertension and patients with cirrhosis subjected to haemorrhage. Excessive formation of nitric oxide is at least partly responsible for the vascular hyporesponsiveness to vasoconstrictors observed in experimental portal hypertension or in rats with haemorrhagic shock. This study investigated whether addition of aminoguanidine, a preferential inducible nitric oxide synthase inhibitor, to glypressin (a long-acting vasopressin analogue) could enhance its portal hypotensive effect in portal-hypertensive rats with bleeding.

2.Portal hypertension was induced by partial portal vein ligation. Fourteen days after operation, systemic and portal haemodynamics were measured in stable or bleeding portal vein-ligated rats receiving intravenous glypressin (0.07 ;mg/kg) or aminoguanidine (70 ;mg/kg) followed by glypressin infusion. In rats with a hypotensive haemorrhage, 4.5 ;ml of blood was withdrawn and 50% of the withdrawn blood was reinfused before the administration of glypressin or aminoguanidine.

3.Glypressin resulted in a significantly greater decrease in portal pressure in portal vein-ligated rats without bleeding than in those with bleeding (P< 0.001). In contrast, glypressin induced similar changes in mean arterial pressure between the two groups (P> 0.05). The addition of aminoguanidine significantly potentiated the portal-hypotensive effect of glypressin in bleeding portal vein-ligated rats (P< 0.005) without an effect on the changes in mean arterial pressure induced by glypressin infusion (P> 0.05).

4.Splanchnic hyposensitivity to glypressin exists in a haemorrhage-transfused rat model of portal hypertension. This hyposensitivity can be ameliorated by the administration of aminoguanidine.
Biliary lactoferrin concentrations are increased in active inflammatory bowel disease: a factor in the pathogenesis of primary sclerosing cholangitis?
Authors: PEREIRA S. P. , RHODES J. M. , CAMPBELL B. J. , KUMAR D. , BAIN I. M. , MURPHY G. M. , DOWLING R. H.
Published: August 2015

1.One hypothesis for the link between inflammatory bowel disease and primary sclerosing cholangitis is that neutrophil activators, such as bacterial chemotactic peptides or neutrophil granule products themselves, pass from the inflamed colon to the liver via an enterohepatic circulation. However, there are no data on biliary concentrations of neutrophil granule products in patients with active and inactive inflammatory bowel disease.

2.Gall bladder bile was obtained at laparotomy from 42 patients with ulcerative colitis and 21 patients with Crohn's disease. Biliary lactoferrin and myeloperoxidase concentrations were quantified by ELISA.

3.In active ulcerative colitis, the mean lactoferrin concentration in gall bladder bile of 2.8±0.40 ;mg/l was higher than that seen after colectomy (1.2±0.11 ;mg/l; P< 0.0001) or in patients with pouchitis (1.8±0.34 ;mg/l; P = 0.06). In active Crohn's colitis, the mean lactoferrin concentration was 3.7±0.9 ;mg/l, compared with 1.1±0.24 ;mg/l in the post-colectomy group (P< 0.05) and 3.1±0.71 ;mg/l in those with active ileitis or ileocolitis. In contrast, biliary myeloperoxidase concentrations were low and comparable in all groups, with a mean concentration in the 42 patients with ulcerative colitis of 11.2±1.9 ;μg/l.

4.In contrast to myeloperoxidase, biliary lactoferrin concentrations are increased in active ulcerative colitis and Crohn's disease, and fall with colectomy and with disease remission. These findings indirectly support the hypothesis that bacterial chemotactic peptides (which induce selective degranulation of neutrophil secondary granules), and/or lactoferrin itself, undergo an enterohepatic circulation.
Erythrocyte Na+/Li+ countertransport and Na+/K+–2Cl− co-transport measurement in essential hypertension: useful diagnostic tools or failure? A meta-analysis of 17 years of literature
Authors: Tepper T. , Sluiter W. J. , Huisman R. M. , de Zeeuw D.
Published: August 2015

1. A meta-analysis of 17 years of literature on erythrocyte Na+/Li+ countertransport (NLCT) and Na+/K+ co-transport (COT) measurements in relation to essential hypertension is presented. The analysis aimed to answer two questions: (i) Which clinical or laboratory variables influence NLCT and COT flux values? (ii) How useful are NLCT and COT measurements as a diagnostic aid in essential hypertension?

2. Regression analysis was performed on the mean flux values and relevant clinical and laboratory values. Studies in both normotensive and hypertensive subjects were stratified for variables which showed a significant association with the measured flux. For hypertensive subjects the studies were also stratified for medication. Means of strata were calculated after weighing the mean of a study by the inverse of its own variance and were compared in normotensive as well as hypertensive subjects using a t-test.

3. The analysis did not demonstrate systematic effects of laboratory variables for either NLCT or COT. It was found that essential hypertension, family history of hypertension, gender and antihypertensive medication are main determinants for the flux values of both transport systems. After stratification for these determinants, significant differences in weighed mean flux values between normotensive and hypertensive subjects were demonstrated. However, these differences are much smaller than the variance in the weighed mean flux values, suggesting the existence of other unknown variables that strongly affect the flux rates.

4. In conclusion, NLCT and COT measurements cannot be of diagnostic use in essential hypertension.
Portal hypertension increases vasoconstrictor responsiveness of rat aorta
Authors: CONNOLLY Claire , CAWLEY Teresa , MCCORMICK P. Aiden , DOCHERTY James R.
Published: August 2015

We have examined the effects of pre-hepatic portal hypertension on the responsiveness of aorta from Wistar and Sprague–Dawley rats. Rats were made portal hypertensive by creating a calibrated portal vein stenosis, or sham operated. In rat aorta, there was no significant difference between portal hypertensive and sham-operated animals in the contractile potency of KCl, noradrenaline or phenylephrine. In aortas from Wistar rats, the maximum response to KCl (0.71±0.12 ;g) and noradrenaline (1.00±0.17 ;g) but not phenylephrine (0.86±0.10 ;g) in portal hypertensive animals was significantly increased compared with that in sham-operated animals (0.45±0.04 ;g, 0.57±0.07 ;g, 0.71±0.05 ;g respectively). In aortas from Sprague–Dawley rats, the maximum response to KCl (1.21±0.21 ;g) and phenylephrine (1.54±0.30 ;g) but not noradrenaline (0.93±0.09 ;g) in portal hypertensive animals was significantly increased compared with that in sham-operated animals (0.59±0.09 ;g, 0.76±0.11 ;g, 1.04±0.10 ;g respectively). There was no difference between portal hypertensive and sham-operated Wistar rats in the affinity or maximum number of binding sites for [3H]prazosin to α1-adrenoceptors in cardiac ventricular membranes. It is concluded that portal hypertension tends to produce an increase rather than a decrease in the contractile response to vasoconstrictors in aorta from both Wistar and Sprague–Dawley rats. This suggests that the diminished responsiveness to vasoconstrictors reported in portal hypertensive rats in vivo is not due to a diminished responsiveness at the level of the vascular smooth muscle.
Increased excretion of nitric oxide in exhaled air of patients with chronic renal failure
Authors: MATSUMOTO Akihiro , HIRATA Yasunobu , KAKOKI Masao , NAGATA Daisuke , MOMOMURA Shin-ichi , SUGIMOTO Tokuichiro , TAGAWA Hitoshi , OMATA Masao
Published: August 2015

Nitric oxide exerts multiple effects on renal function. It remains unclear whether endogenous nitric oxide production is increased or decreased in patients with chronic renal failure. To evaluate endogenous nitric oxide production in these patients we studied exhaled nitric oxide output by an ozone chemiluminescence method and plasma NO2-/NO3- levels by the Griess method in 40 patients with end-stage chronic renal failure who underwent regular continuous ambulatory peritoneal dialysis (n = 30) or haemodialysis (n = 10), and in 28 healthy subjects. Patients with chronic renal failure had a higher exhaled nitric oxide concentration [39±3 versus 19±1 parts per billion, (mean±S.E.M.), P< 0.0001], a greater nitric oxide output (177±11 versus 96±7 ;nl·min-1·m-2, P< 0.001) and a higher plasma NO2-/NO3- concentration (96±14 versus 33±4 ;μmol, P< 0.01) than controls. These values did not differ between patients on haemodialysis and those on continuous ambulatory peritoneal dialysis. Patients with chronic renal failure had significantly higher plasma concentrations of both interleukin-1β and interferon-γ than controls. The exhaled nitric oxide output did not correlate with plasma NO2-/NO3- or with peritoneal dialysate NO2-/NO3-, but plasma NO2-/NO3- correlated with dialysate NO2-/NO3- in patients who underwent continuous ambulatory peritoneal dialysis (r = 0.77, P< 0.01). Haemodialysis for 4 ;h acutely decreased plasma NO2-/NO3- (92±17 versus 50±8 ;μmol, P< 0.05) and cGMP concentration (16.5±4.3 versus 5.1±1.7 ;pmol/ml, P< 0.01), but did not decrease exhaled nitric oxide output. The increase in exhaled nitric oxide with the simultaneous increase in circulating cytokines suggests that nitric oxide synthase seems to be induced significantly in patients with chronic renal failure. Increased endogenous nitric oxide production may have a pathophysiological role in patients with uraemia.
Inhibition of mitogen-activated proliferation of human peripheral lymphocytes in vitro by propionic acid
Authors: WAJNER Moacir , SANTOS Kátia D. , SCHLOTTFELDT Jeanine L. , ROCHA Maureen P. , WANNMACHER Clóvis M. D.
Published: August 2015

Recurrent infections are common features in patients affected by propionic acidaemia (McKusick 232000) and methylmalonic acidaemia (McKusick 251000). Since these disorders are biochemically characterized by tissue accumulation of propionic acid and methylmalonic acid respectively, it is possible that these compounds may act as immunosuppressants. We therefore investigated the effect of propionate and methylmalonate on cellular growth of human peripheral lymphocytes stimulated in vitro by phytohaemagglutinin, concanavalin A and pokeweed mitogen, a recognized test of cellular immunocompetence. Lymphocytes were cultured in flat-bottomed 96-well microplates at 37 ;°C for 96 ;h (phytohaemagglutinin and concanavalin A) or 144 ;h (pokeweed mitogen) in the presence of one mitogen at different concentrations and of one acid added at doses of 1.0, 2.5 or 5.0 ;mM. Cell blastogenesis was measured by the incorporation of tritiated thymidine into cellular DNA and compared with that of identical cultures with no acid added (controls). A consistent and progressive inhibitory effect of propionic acid with increasing concentrations in culture was identified with all mitogens and was more pronounced with pokeweed mitogen. Lymphocyte blastogenesis was not altered in the presence of methylmalonic acid. The effect of propionate was observed only when the drug was added at the beginning (phytohaemagglutinin-activated) or until 24 ;h (concanavalin A- and pokeweed mitogen-activated) of culture. The viability of lymphocytes after treatment with the drug, as assessed by the Trypan Blue exclusion test, revealed no change when compared with the same untreated lymphocytes, indicating no lymphocytotoxic activity. In conclusion, propionic acid, which accumulates in tissues of patients with propionic acidaemia, causes ‘in vitro’ immunosuppression, which may be related to the recurrent infections characteristic of these patients.
Changes in indices of antioxidant status, lipid peroxidation and inflammation in human skeletal muscle after eccentric muscle actions
Authors: CHILD R. , BROWN S. , DAY S. , DONNELLY A. , ROPER H. , SAXTON J.
Published: August 2015

This study investigated the effects of chronic muscle inflammation on indices of antioxidant status and muscle injury after eccentric exercise. Eight subjects each performed 70 maximal voluntary eccentric muscle actions on an isokinetic dynamometer, using the knee extensors of a single leg. Venous blood samples were collected into serum and EDTA tubes 5 and 3 days before exercise, immediately before exercise, and then again on days 3, 4, 5, 6, 7, 10 and 12 after the bout. Needle biopsies were taken from the vastus lateralis of six subjects, a week before exercise (baseline), and again on days 4 and 7 post-exercise. The concentrations of malondialdehyde in plasma and muscle were used as markers of lipid peroxidation. Creatine kinase activity, β-glucuronidase activity and total antioxidant capacity were determined in serum. In muscle, aqueous and bound total antioxidant capacity, the aqueous sulphydryl concentration, and β-glucuronidase and glucose-6-phosphate dehydrogenase activity were determined. No changes were detected in serum total antioxidant capacity, serum creatine kinase and β-glucuronidase after the baseline biopsy. After exercise serum creatine kinase and β-glucuronidase were elevated although other serum measures were unchanged. In muscle, aqueous and bound total antioxidant capacity, sulphydryls, glucose-6-phosphate dehydrogenase and β-glucuronidase were all elevated. Despite evidence of inflammation in this study, muscle antioxidant status was not compromised, and malondialdehyde was unaltered in muscle and plasma. Therefore, this study provides no evidence that chronic muscle inflammation compromises antioxidant status or increases lipid peroxidation.
Endothelial dysfunction by acute hyperhomocyst(e)inaemia: restoration by folic acid
Authors: USUI Michiaki , MATSUOKA Hidehiro , MIYAZAKI Hiroshi , UEDA Seiji , OKUDA Seiya , IMAIZUMI Tsutomu
Published: August 2015

Recent evidence demonstrates that hyperhomocyst(e)inaemia is a novel risk factor for cardiovascular diseases. In patients with chronic hyperhomocyst(e)inaemia, endothelial function is impaired. However, whether hyperhomocyst(e)inaemia per se is a cause or an epiphenomenon of endothelial dysfunction remains unknown. In this study, we examined the effects of methionine-induced acute hyperhomocyst(e)inaemia on human endothelial function. In healthy volunteers we administered methionine (0.1 ;g/kg body weight, per os), a substrate of homocyst(e)ine, with or without folic acid (20 ;mg, per os) and examined flow-mediated vasodilatation of the brachial artery by high-resolution ultrasonography as a non-invasive measure of endothelial function. We also measured plasma levels of homocyst(e)ine before and 3, 8 and 24 ;h after methionine loading. Methionine administration increased plasma levels of homocyst(e)ine by four times the basal level at 8 ;h (P< 0.0001, ANOVA). The plasma levels returned to baseline at 24 ;h. Flow-mediated vasodilatation was significantly decreased to half of the baseline value at 8 ;h and returned to baseline at 24 ;h (P< 0.0001, ANOVA), whereas endothelium-independent vasodilatation by glyceryl trinitrate was not affected by the methionine loading. Co-administration of folic acid did not attenuate methionine-induced hyperhomocyst(e)inaemia but completely prevented endothelial dysfunction. Our results suggest that in humans a methionine-rich diet may acutely impair endothelial function, which can be prevented by folic acid supplementation.
Effects of chronic nitric oxide activation or inhibition on early hepatic fibrosis in rats with bile duct ligation
Authors: MAYORAL Paula , CRIADO Manuela , HIDALGO Froilan , FLORES Olga , ARÉVALO Miguel A. , ELENO Nélida , SÁNCHEZ-RODRÍGUEZ Angel , LÓPEZ-NOVOA Jose M. , ESTELLER Alejandro
Published: August 2015

Hepatic fibrosis or increased liver collagen contents drive functional abnormalities that, when extensive, may be life threatening. The purpose of this study was to assess the effects of the chronic stimulation or inhibition of nitric oxide synthesis in rats with hepatic fibrosis induced by permanent common bile duct ligation (3 weeks) and the role of expression of the different nitric oxide synthase isoforms. Bile duct ligation led to an important accumulation of collagen in the hepatic parenchyma, as shown both histologically and by the hydroxyproline contents of livers. Bilirubin and serum enzyme activities (measured as markers of cholestasis) increased several-fold after bile duct ligation. The area of fibrotic tissue, liver hydroxyproline content and serum markers of cholestasis were clearly related in obstructed rats. The absence of modifications in haemodynamic parameters excludes circulatory changes from being responsible for the development of liver alterations. In animals treated with NG-nitro-L-arginine methyl ester (L-NAME) the area of fibrosis was similar to that of untreated animals, the signs of cholestasis and cellular injury being more evident. In rats treated with L-arginine the area of fibrosis was almost three times larger than that found in bile duct ligated rats and in L-NAME-treated bile duct ligated rats, although the observed biochemical changes were similar to those seen in rats treated with L-NAME. Our results with inducible nitric oxide synthase, obtained by Western blots and immunohistochemistry, indicate a greater expression of the inducible enzyme in bile duct ligated and L-arginine-treated animals and a lower expression in the L-NAME and control groups. Constitutive nitric oxide synthase expression, obtained by Western blots, was very similar in all groups, except for the L-arginine-treated rats in which it was lower. These results suggest that nitric oxide production may be a key factor in the development of fibrosis in bile duct ligated rats. They also support the hypothesis of a dual role for nitric oxide; one beneficial, mediated by its circulatory effects, and the second negative, through its local toxic effects.
Is normal pregnancy atherogenic?
Authors: MARTIN U. , DAVIES C. , HAYAVI S. , HARTLAND A. , DUNNE F.
Published: August 2015

Serum cholesterol, triacylglycerols and low-density lipoprotein (LDL) subfractions were determined in 120 primagravid women during normal gestation (40 in each trimester) and in 20 non-pregnant age-matched controls. LDL subfractions were determined by PAGE, and an LDL score was calculated. The higher the score, the smaller the subfractions. The objective of the study was to determine the effects of the hyperlipidaemia, high oestrogen concentrations and insulin resistance known to exist in normal pregnancy on LDL subfraction formation. Pregnant women had an increased mean serum cholesterol concentration [5.78 (S.D. 1.09) mmol/l] in the first trimester compared with the non-pregnant controls [5.11 (0.77) mmol/l; P< 0.01]. The serum cholesterol concentration increased progressively throughout gestation to a mean of 8.14 (1.39) mmol/l in the third trimester (P< 0.001 compared with the second trimester). Triacylglycerol concentrations in the first trimester were similar to those of controls, and there was a non-significant increase by the second trimester to 1.32 (0.44) mmol/l. However, by the third trimester the mean triacylglycerol concentration had doubled [2.58 (0.98) mmol/l; P< 0.001 compared with the first and second trimester]. During gestation the LDL score increased dramatically, from 1.17 (0.39) during the first trimester to 2.01 (0.37) in the second trimester (P< 0.001) to 2.73 (0.48) in the third trimester (P< 0.001 compared with the second trimester). Thus an atherogenic lipid profile develops during normal gestation. The significance of these changes remains unclear, but thay may have important implications for mother and foetus.
Elevated plasma levels of adrenomedullin in congenital cyanotic heart disease
Authors: YOSHIBAYASHI Muneo , KAMIYA Tetsuro , NISHIKIMI Toshio , SAITO Yoshihiko , MATSUO Hisayuki , KANGAWA Kenji
Published: August 2015

Adrenomedullin is a novel hypotensive peptide originally isolated from human pheochromocytoma. Accumulating evidence suggests the possible involvement of adrenomedullin in the physiology of the pulmonary circulation and the pathophysiology of hypoxaemia. The aim of the present study was to investigate the pathophysiological significance of adrenomedullin in hypoxaemia caused by congenital cyanotic heart disease. Subjects were 16 patients with congenital cyanotic heart disease aged 0.8–10 years (Group C) and 12 age-matched control subjects (patients with coronary artery dilatation after Kawasaki disease; Group N). Plasma adrenomedullin concentrations were measured, using radioimmunoassay, in femoral venous, pulmonary arterial and pulmonary venous blood obtained during cardiac catheterization. Plasma adrenomedullin concentrations in Group C were significantly (3-fold) higher than those in Group N at all sampling sites. In Group C, plasma adrenomedullin concentrations in pulmonary venous blood were significantly lower than those in pulmonary arterial blood. Pulmonary uptake of adrenomedullin in Group C was significantly greater than that in Group N. Patients with congenital cyanotic heart disease showed elevated plasma adrenomedullin concentrations and an increased uptake of adrenomedullin in the pulmonary circulation, which may act to dilate pulmonary vessels and increase pulmonary blood flow to alleviate hypoxaemia. Intrinsically increased adrenomedullin levels may function as a compensatory mechanism for hypoxaemia in congenital cyanotic heart disease.
Dissociation between microneurographic and heart rate variability estimates of sympathetic tone in normal subjects and patients with heart failure
Authors: NOTARIUS Catherine F. , BUTLER Gary C. , ANDO Shin-ichi , POLLARD Michael J. , SENN Beverley L. , FLORAS John S.
Published: August 2015

The concept that spectral analysis of heart rate variability (HRV) can estimate cardiac sympathetic nerve traffic in subjects with both normal and impaired left ventricular systolic function has not been validated against muscle sympathetic nerve activity (MSNA). We used coarse-graining spectral analysis to quantify the harmonic and non-harmonic, or fractal, components of HRV and to determine low-frequency (0.0–0.15 Hz; PL) and high-frequency (0.15–0.5 Hz; PH) harmonic power. To test the hypothesis that MSNA and HRV representations of sympathetic nerve activity (PL and PL/PH) increase in parallel in heart failure, we recorded heart rate and MSNA during supine rest in 35 patients (age 52.4±2 years; mean±S.E.M.), with a mean left ventricular ejection fraction of 22±2%, and in 34 age-matched normal subjects. Power density was log10 transformed. Mean MSNA was 52.9±2.6 bursts/min in heart failure patients and 34.9±1.9 bursts/min in normal subjects (P < 0.0001). In normal subjects, but not in heart failure patients, total power (PT) (r = -0.41; P = 0.02) and fractal power (PF) (r = -0.36; P = 0.04) were inversely related to age. In heart failure patients, total and fractal power were reduced (P < 0.009 for both), and were inversely related to MSNA burst frequency (r = -0.55, P = 0.001 and r = -0.60, P = 0.0003 respectively). In normal subjects, there was no relationship between MSNA and either PL or PH. In heart failure patients, as anticipated, PH was inversely related to MSNA (r = -0.41; P < 0.02). However, PL was also inversely rather than directly related to MSNA (r = 0.44 for 1/log10 PL; P < 0.01). There was no relationship between other sympathetic (PL/PH) or parasympathetic (PH/PT) indices and MSNA in either heart failure patients or normal subjects. The lack of concordance between these direct and indirect estimates of sympathetic nervous system activity indicates that this component of HRV cannot be used for between-subject comparisons of central sympathetic nervous outflow. It is the absence of low-frequency power that relates most closely to sympathetic activation in heart failure.
Physiological control of splanchnic blood flow by adrenaline: studies during acute hypoglycaemia in man
Authors: PARKER David R. , BRAATVEDT Geoffrey D. , HALLIWELL Michael , CORRALL Roger J. M.
Published: August 2015

Superior mesenteric artery blood flow (SMABF) increases significantly during and after the hypoglycaemia reaction in healthy humans. To investigate the mechanisms controlling this phenomenon, SMABF and plasma catecholamines were measured in healthy human volunteers. In 10 controls, hypoglycaemia was induced by insulin infusion (2.5 m-units·min-1·kg-1). In six subjects, β-blockade by propranolol infusion (0.7 µg·min-1·kg-1) preceded insulin infusion and was continued throughout the study. Following the hypoglycaemia reaction, the glucose nadir was similar in both groups. In controls, increases in SMABF [42.4±6.1% (mean±S.E.M.); P < 0.001], cardiac output (34.3±2.3%; P < 0.001) and pulse rate (from 63.9±2.7 to 82.5±3.1 beats/min; P < 0.001) occurred. Superior mesenteric artery resistance fell by 32.4±3.3% (P < 0.001). Under β-blockade, decreases in SMABF (34.8±2.9%; P < 0.001) and pulse rate (from 59.5±0.2 to 51.8±2.2 beats/min; P < 0.001) occurred. Superior mesenteric artery resistance increased (peak +30.8±12.3%; not significant). Subjects showed greater increases in adrenaline (P < 0.006) and noradrenaline (P < 0.022) concentrations than controls. Mesenteric hyperaemia associated with hypoglycaemia in man appears to be mediated by a β-adrenergic mechanism that is activated by increased circulating levels of adrenaline.
Does potassium channel opening contribute to endothelium-dependent relaxation in human internal thoracic artery?
Authors: HAMILTON C. A. , BERG G. , MCARTHUR K. , REID J. L. , DOMINICZAK A.F.
Published: August 2015

Opening of potassium channels can cause hyperpolarization and relaxation of vascular smooth muscle cells. The aim of this work was to investigate the contribution of potassium channel activation to vasorelaxation in internal thoracic artery taken from patients undergoing coronary artery bypass graft surgery. Relaxations to carbachol and sodium nitroprusside were studied in isolated rings of internal thoracic artery in the absence and presence of nitric oxide synthase inhibitors and potassium channel blockers. The nitric oxide synthase inhibitors Nω-nitro-⌊-arginine methyl ester and NG-monomethyl-⌊-arginine abolished relaxations to carbachol. Relaxations to both carbachol and sodium nitroprusside were attenuated in the presence of raised extracellular potassium and the potassium channel blockers charybdotoxin, iberiotoxin and tetraethylammonium. Neither apamin nor glibenclamide modified relaxation. ODQ (1H-[1,2,4]oxadiazolol-[4,3a] quinoxalin-1-one), an inhibitor of soluble guanylate cyclase, abolished relaxation to carbachol in rings from some but not all subjects. These results suggest that potassium channel opening may make a small contribution to endothelium-dependent vasorelaxation in internal thoracic artery. The potassium channels had characteristics consistent with those of large-conductance calcium-dependent potassium channels.
Insulin gene polymorphism and premature male pattern baldness in the general population
Authors: ELLIS Justine A. , STEBBING Margaret , HARRAP Stephen B.
Published: August 2015

Insulin is found in hair follicles and may play a role in the regulation of androgen metabolism and the hair growth cycle, which are relevant to the loss of scalp hair known as male pattern baldness. An excess of dihydrotestosterone on balding scalp indicates that the condition is androgen dependent. Premature male pattern baldness may be the male phenotype of familial polycystic ovary syndrome, a condition characterized by high levels of androgens and insulin that has been linked to insulin gene polymorphism. Therefore, we studied possible associations between relevant insulin gene polymorphisms and premature male pattern baldness in the general community. We examined the distribution of three dimorphic restriction fragment length polymorphisms: HphI, PstI and FokI in cases consisting of 56 men aged 18–30 years with significant baldness, and in 107 control men aged 50 years or more with no indication of baldness. No significant differences between cases and controls in allele, genotype or haplotype frequencies were identified. We conclude that, in the general population, the insulin gene is not associated with premature male pattern baldness.
Regulation of 11β-hydroxysteroid dehydrogenase type 2 by diuretics and the renin–angiotensin–aldosterone axis
Authors: RICKETTS Marie L. , STEWART Paul M.
Published: August 2015

In the kidney and colon 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) inactivates cortisol to cortisone, thereby protecting the non-selective mineralocorticoid receptor from cortisol. Deficiency of 11β-HSD2 results in cortisol-mediated sodium retention and hypertension, suggesting that the physiological regulation of 11β-HSD2 in mineralocorticoid target tissues may be important in modulating sodium homoeostasis and blood pressure control. Using the human epithelial colon cell line SW-620, reverse transcriptase-polymerase chain reaction and enzyme kinetic analysis indicated expression of only 11β-HSD2 (Km for cortisol 66 nmol/l). Bradykinin (10-8 to 10-12 mol/l), frusemide (10-4 to 10-9 mol/l), benzamiloride hydrochloride (10-5 to 10-10 mol/l) and atrial natriuretic peptide (10-6 to 10-10 mol/l) had no effect on 11β-HSD2 expression. Using a range of concentrations of angiotensin II (2×10-8 to 2×10-5 mol/l) a significant reduction in activity was seen but only at supra-physiological concentrations, [e.g. 2×10-6 mol/l at 4 h pretreatment: 36.7±2.0 pmol cortisone·h-1·mg-1 (mean±S.E.M.) compared with 45.1±1.7 pmol·h-1·mg-1 in control; P < 0.05]. The angiotensin-converting enzyme inhibitors captopril, enalapril, lisinopril, perindopril, quinapril and trandolapril at 10-7 mol/l, but not fosinopril, significantly increased 11β-HSD2 activity after pretreatment for 16 or 24 h (P < 0.05-P < 0.01 compared with control). No effects were seen at 4 h pretreatment. Hydrochlorothiazide (10-7 mol/l) significantly decreased 11β-HSD2 activity (P < 0.05 compared with control) at 4 h pretreatment. Commonly used diuretics, atrial natriuretic peptide and physiological concentrations of angiotensin II and bradykinin do not alter 11β-HSD2 activity. In contrast, a series of angiotensin-converting enzyme inhibitors significantly increase 11β-HSD2 activity in vitro. This may explain how intrarenal infusions of angiotensin-converting enzyme inhibitors increase renal sodium excretion independent of circulating concentrations of angiotensin II. The interaction between angiotensin-converting enzyme inhibitors and 11β-HSD2 may be an additional mechanism by which the former can lower blood pressure.
Prevalence of sleep/wake disorders in persons with blindness
Authors: LEGER Damien , GUILLEMINAULT Christian , DEFRANCE Remy , DOMONT Alain , PAILLARD Michel
Published: August 2015

Blind individuals are not only handicapped by their loss of vision, but are also affected because the loss of sight may have a secondary impact on functioning of their biological clock. The objective of the present study was to determine the impact of visual loss on sleep/wake disorders. A prospective 48-item questionnaire survey was distributed to blind individuals through the French Association Valentin Haüy, which serves blind persons. A control group matched by age, sex, geographical location and professional activity/non-activity was obtained from a panel of 20000 households representative of the French population, and this group also completed the questionnaire. From a potential blind population of 1500 subjects, 1073 questionnaires (71.5%) were completed and usable for analysis, and from a potential 1000 control subjects, 794 (79.4%) of the questionnaires were returned and analysed. Criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders, 4th revision, and the International Classification of Sleep/Wake Disorders (1990) were used to determine pathology. Individuals determined to be ‘totally blind’ and ‘almost blind’ (i.e. with less than 10% vision left in only one eye) presented a significantly higher occurrence of sleep/wake disorders than controls. Nocturnal sleep disruption, daytime somnolence, and (to a lesser degree) a ‘free-running’ condition are significantly more common in blind individuals. There is an increased use of sleeping pills, and a higher incidence of inappropriate involuntary daily naps. In conclusion, individuals with blindness report a significant curtailment of total sleep time and hence resulting daytime somnolence, which impacts on daytime activities. A ‘free-running’ condition is also a common sleep/wake impairment that may compound the handicap of blindness.
Assessment of the stability of N-terminal pro-brain natriuretic peptide in vitro: implications for assessment of left ventricular dysfunction
Authors: DOWNIE P. F. , TALWAR S. , SQUIRE I. B. , DAVIES J. E. , BARNETT D. B. , NG L. L.
Published: August 2015

Plasma concentrations of N-terminal pro-brain natriuretic peptide (NT-proBNP) are raised in patients with left ventricular dysfunction. Measurement of this peptide has a potential diagnostic role in the identification and assessment of patients with heart failure. The stability of this peptide over time periods and conditions pertaining to routine clinical practice has not been reported previously. Blood samples were obtained from 15 subjects. One aliquot was processed immediately, and the remaining portions of the blood samples were stored for 24 h or 48 h at room temperature or on ice prior to processing. Plasma concentrations of NT-proBNP were measured with a novel immunoluminometric assay developed within our laboratory. Mean plasma concentrations of NT-proBNP were not significantly different whether blood samples were centrifuged immediately and stored at -70 °C or kept at room temperature or on ice for 24 h or 48 h. The mean percentage differences from baseline (reference standard) were +5.2% (95% confidence interval +18.2 to -7.8%) and +0.8% (+15.2 to -13.7%) after storage for 24 h at room temperature or on ice respectively, and +8.9% (+24.2 to -6.5%) and +3.2% (+15.1 to -0.9%) for storage for 48 h at room temperature or on ice respectively. Pearson correlation coefficients for baseline NT-proBNP concentrations compared with levels at 48 h at room temperature or on ice were r = 0.89 and r = 0.83 respectively (both P < 0.0001). Thus NT-proBNP extracted from plasma samples treated with EDTA and aprotinin is stable under conditions relevant to clinical practice.