bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Acute and Chronic Caffeine Use on the Cerebrovascular, Cardiovascular and Hormonal Responses to Orthostasis in Healthy Volunteers
Authors: Debrah Kwasi , Haigh Rob , Sherwin Robert , Murphy June , Kerr David 
Published: August 2015

1. The effects of acute and chronic caffeine ingestion on supine- and tilt- (60 min at 70°) induced changes in middle cerebral artery velocity (Vmca), heart rate, blood pressure and counter-regulatory hormone levels (catecholamines, growth hormone and cortisol) were studied in nine healthy volunteers. A double-blind, placebo-controlled design was used to study acute effects followed by an open study after 6 days of chronic caffeine use.
2. In the supine position, acute ingestion of caffeine (250 mg) was associated with a fall in Vmca [−11 cm/s, point estimate of difference versus placebo (95% confidence interval: −17, −6) cm/s, P &lt; 0.001] and a rise in mean arterial pressure [+4 (1, 6) mmHg, P &lt; 0.01] and plasma adrenaline levels [+138 (53, 223) pmol/l, P &lt; 0.01]. After chronic caffeine use, the pressor and adrenaline responses, but not the drop in Vmca, were significantly attenuated.
3. On tilting to 70° the fall in Vmca was greater with placebo than after acute caffeine ingestion [−10 (−14, −15) cm/s, P &lt; 0.01], whereas increments (above supine values) in heart rate, mean arterial pressure and hormone levels were unchanged by caffeine. In contrast, the adrenaline [+126 (29, 282) pmol/l, P &lt; 0.01] and noradrenaline [+ 0.6 (0.1, 0.9) nmol/l, P &lt; 0.05] responses to tilting were augmented after acute caffeine ingestion. Chronic caffeine supplementation did not alter the fall in Vmca associated with tilting, but significantly attenuated the adrenaline response (P &lt; 0.01 compared with the acute study).
4. Acute caffeine ingestion and orthostasis are both associated with a reduction in Vmca and a rise in mean arterial pressure and adrenaline levels. The acute effects of caffeine on mean arterial pressure and adrenaline but not on Vmca are lost with sustained caffeine intake. These results suggest dissociation between the development of central and peripheral tolerance after chronic caffeine use.
Low Selenium Status in the Elderly Influences Thyroid Hormones
Authors: Olivieri Oliviero , Girelli Domenico , Azzini Margherita , Stanzial Anna Maria , Russo Carla , Ferroni Massimiliano , Corrocher Roberto 
Published: August 2015

1. Iodothyronine 5′-deiodinase, which is mainly responsible for peripheral triiodothyronine (T3) production, has recently been demonstrated to be a selenium-containing enzyme. In the elderly, reduced peripheral conversion of thyroxine (T4) to T3 and overt hypothyroidism are frequently observed.
2. We measured serum selenium and erythrocyte glutathione peroxidase (as indices of selenium status), thyroid hormones and thyroid-stimulating hormone in 109 healthy euthyroid subjects (52 women, 57 men), carefully selected to exclude abnormally low thyroid hormone levels induced by acute or chronic diseases or calorie restriction. The subjects were subdivided into three age groups. To avoid conditions of undernutrition or malnutrition, dietary records were obtained for a sample of 24 subjects, randomly selected and representative of the whole population for age and sex.
3. In order to properly assess the influence of selenium status on iodothyronine 5′-deiodinase type I activity, a double-blind placebo-controlled trial was also carried out on 36 elderly subjects, resident at a privately owned nursing home.
4. In the free-living population, a progressive reduction of the T3/T4 ratio (due to increased T4 levels) and of selenium and erythrocyte glutathione peroxidase activity was observed with advancing age. A highly significant linear correlation between T4, T3/T4 and selenium was observed in the population as a whole (for T4, R = −0.312, P &lt; 0.002; for T3/T4 ratio, R = 0.32, P &lt; 0.01) and in older subjects (for T4, R = −0.40, P &lt; 0.05; for T3/T4 ratio, R = 0.54, P &lt; 0.002).
5. The main result of the double-blind placebo-controlled trial was a significant improvement of selenium indices and a decrease in the T4 level in selenium-treated subjects; serum selenium, erythrocyte glutathione peroxidase activity and thyroid hormones did not change in placebo-treated subjects.
6. We concluded that selenium status influences thyroid hormones in the elderly, mainly modulating T4 levels.
Effects of Depolarizing or Non-Depolarizing Preservation Solutions on Human Endothelial cells during Cold Hypoxia
Authors: Hidalgo M. A. , Mann D. J. , Fuller B. J. , Green C. J. 
Published: August 2015

1. Hypothermic storage of whole organs flushed with a preservation solution is common practice in clinical transplantation. This procedure leaves vascular endothelial cells in direct contact with the preservation solution during the length of the cold ischaemic period.
2. Aiming to study the effects of organ preservation on vascular endothelium, we subjected cultures of human umbilical vein endothelial cells to hypoxic and hypothermic storage conditions in vitro for 3 or 16 h. Four preservation solutions with different levels of sodium and potassium were tested. Morphometric analysis and 51Cr leakage index were used to assess monolayer continuity, cell viability and membrane integrity.
3. Hypothermic storage resulted in severe changes in endothelial cell morphology with formation of intercellular gaps that destroyed monolayer continuity after only 3 h. Cellular blebbing was a common feature in seriously damaged cells.
4. Morphometric analysis and 51Cr leakage results correlated well. No significant differences between the solutions tested were found after 3 h of hypothermic hypoxic storage. After 16 h, viability and monolayer continuity were significantly better preserved (Mann—Whitney, P &lt; 0.01) in cells stored in lactobionate-based solutions than in hypertonic citrate solutions. No significant differences were found between endothelial cells stored in extracellular versus intracellular types of solutions for the lactobionate-based solutions.
5. The results of the present experiment showed that after a period of hypothermic hypoxic storage, vascular endothelial cells appeared morphologically deformed and poorly attached in vitro. Lactobionate-based preservation solutions were more effective in preserving viability and continuity. Protection of vascular endothelium under cold hypoxic conditions could be a critical factor in successfully preserving organs for transplantation.
Alteration of Atrial Natriuretic Peptide and Brain Natriuretic Peptide Gene Expression Associated with Progression and Regression of Cardiac Hypertrophy in Renovascular Hypertensive Rats
Authors: Kawakami Hideo , Okayama Hideki , Hamada Mareomi , Hiwada Kunio 
Published: August 2015

1. We assessed the changes of atrial natriuretic peptide and brain natriuretic peptide gene expression associated with progression and regression of cardiac hypertrophy in renovascular hypertensive rats (RHR).
2. Two-kidney, one-clip hypertensive rats (6-week-old male Wistar) were made and studied 6 (RHR-1) and 10 weeks (RHR-2) after the procedure. Regression of cardiac hypertrophy was induced by nephrectomy at 6 weeks after constriction, and the nephrectomized rats were maintained further for 4 weeks (nephrectomized rat: NEP). Sham operation was performed, and the rats were studied after 6 (Sham-1) and 10 weeks (Sham-2). Atrial natriuretic peptide and brain natriuretic peptide gene expression in the left ventricle was analysed by Northern blotting.
3. Plasma atrial natriuretic peptide and brain natriuretic peptide were significantly higher in RHR-1 and RHR-2 than in Sham-1, Sham-2 and NEP. Atrial natriuretic peptide and brain natriuretic peptide mRNA levels in RHR-1 were approximately 7.2-fold and 1.8-fold higher than those in Sham-1, respectively, and the corresponding levels in RHR-2 were 13.0-fold and 2.4-fold higher than those in Sham-2, respectively. Atrial natriuretic peptide and brain natriuretic peptide mRNA levels of NEP were normalized. Levels of atrial natriuretic peptide and brain natriuretic peptide mRNA were well correlated positively with left ventricular weight/body weight ratios. There was a significant positive correlation between the levels of atrial natriuretic peptide and brain natriuretic peptide mRNA (r = 0.86, P&lt;0.01).
4. We conclude that the expression of atrial natriuretic peptide and brain natriuretic peptide genes is regulated in accordance with the degree of myocardial hypertrophy and that the augmented expression of these two natriuretic peptides may play an important role in the maintenance of cardiovascular haemodynamics in renovascular hypertension.
Effects of Hypercholesterolaemia on Physiological Recruitment of Coronary Vascular Reserve in Swine
Authors: Bergelson Bruce A. , Yu Tse-Kuan , Ruocco Nicholas A. 
Published: August 2015

1. The endothelium participates in the regulation of coronary vascular tone. As evidence exists from studies performed on epicardial vessels that hypercholesterolaemia impairs endothelial function, we tested the hypothesis that hypercholesterolaemia impairs coronary vascular reserve in an intact animal.
2. Domestic swine, maintained on a regular (n = 9) or a 2% high-cholesterol (n = 9) diet for 3 months were instrumented with a catheter in the left atrium for microsphere injection, a catheter in the anterior interventricular vein for venous sampling and an 82% stenosis in the left anterior descending artery. Papaverine was used to determine coronary vascular reserve. Regional coronary flow as reflected by perfusion (microsphere measurement), lactate consumption, oxygen consumption and haemodynamics were obtained at baseline, after 10 mg of papaverine and after atrial pacing at a rate of 120 beats/min and 150 beats/min.
3. Cholesterol was elevated in animals on the high cholesterol diet (350 ± 50 mg/dl versus 99 ± 10 mg/dl, P&lt;0.001). Baseline haemodynamics were similar between groups. Baseline transmural flow and its augmentation with papaverine were comparable in the two groups in the control (circumflex) and stenosed (left anterior descending artery) zones. In both groups, perfusion increased in the control zone in response to increased oxygen demand, whereas in the stenosis zone no increase was observed in either group (P not significant for normal versus high cholesterol diet). Endocardial flow reserve in the stenosis zone was exhausted in both groups. Epicardial flow in the stenosis zone increased significantly in the normal (P&lt;0.02) but not in the hypercholesterolaemic animals (P not significant).
4. The endocardial/epicardial ratio in the control zone at baseline revealed greater endocardial dominance in the normal compared with the hypercholesterolaemic animals (1.35 versus 1.10, P&lt;0.01). With papaverine, similar ratios indicated a similar reserve potential in both groups. During increased oxygen demand, normal animals continued to demonstrate endocardial dominance whereas it diminished in the hypercholesterolaemic group. In the stenosis zone, endocardial blood flow dominated at baseline in the normal animals and to a lesser extent in the hypercholesterolaemic animals (1.30 versus 1.10, P = 0.10). During increased oxygen demand, endocardial dominance decreased significantly in both groups of animals; however, it remained greater than 1.0 only in the normal animals.
5. Exposure to elevated cholesterol levels did not impair an animal's ability to augment coronary blood flow in response to an increase in oxygen demand. In contrast to this lack of effect on recruitment of coronary reserve, regional coronary blood flow was altered in the hypercholesterolaemic animals.
Enhanced Phospholipase A2 Activity in Cultured Cardiomyocytes from Newborn Spontaneously Hypertensive Rat
Authors: Brussel Elisabeth Millanvoye-Van , Devynck Marie-Aude 
Published: August 2015

1. Changes in membrane lipid composition and metabolism could participate in myocardial membrane dysfunction in essential or experimental hypertension. Phospholipid-bound fatty acid profile and metabolism are altered in cultured heart myocytes of newborn genetically hypertensive rats. The present study was designed to investigate the participation of phospholipase A2 in these modifications. 2. Phospholipase A2 activity of cultured cardiomyocytes of neonate spontaneously hypertensive rats and normotensive control Wistar—Kyoto rats was compared. The enzyme activity was measured using 2-[1-14C]arachidonyl-phosphatidylethanolamine as substrate. In both strains, Ca2+-dependent and independent phospholipase A2 activities were present. Only the Ca2+-dependent enzyme activity was altered in spontaneously hypertensive rat cardiomyocytes. With 0.2 mmol/l substrate and 5 mmol/l Ca2+, the phospholipase A2 activities were 79.0 ± 13.4 and 26.0 ± 3.6 nmol h−1 mg−1 of protein in spontaneously hypertensive and Wistar—Kyoto rat cardiomyocytes respectively (n = 10 in both cases, P = 0.001). The maximum velocity of the enzyme was three times higher in spontaneously hypertensive rat than in Wistar—Kyoto rat, without changes in the apparent affinity of the enzyme for its substrate.
3. The present results demonstrate an enhanced phospholipase A2 activity in cultured heart muscle cells of spontaneously hypertensive rats, which could be genetically determined.
Impact of Changes in Respiratory Frequency and Posture on Power Spectral Analysis of Heart Rate and Systolic Blood Pressure Variability in Normal Subjects and Patients with Heart Failure
Authors: Sanderson John E. , Yeung Leata Y. C. , Yeung Dickens T. K. , Kay Richard L. C. , Tomlinson Brian , Critchley J. A. J. H. , Woo Kam S. , Bernardi Luciano 
Published: August 2015

1. Autonomic dysfunction is a major feature of congestive cardiac failure and may have an important role in determining progression and prognosis. The low-frequency/high-frequency ratio derived from power spectral analysis of heart rate variability has been proposed as a non-invasive method to assess sympatho-vagal balance. However, the effects of different respiratory rates or posture are rarely accounted for, but may be relevant in patients with heart failure in whom clinical improvement is accompanied by a fall in respiratory rate and an increased proportion of the day in the upright position.
2. We have assessed the effect of controlled respiration at different rates (10, 15, 20 breaths/min or 0.17, 0.25 and 0.33 Hz), while supine and standing, on power spectral analysis of heart rate and blood pressure variability in 11 patients with heart failure and 10 normal subjects.
3. Heart rate variance and low-frequency power (normalized units) were reduced in patients with heart failure (absent in six). During controlled breathing while supine, the power of the high-frequency component was significantly greater at 10 breaths/min than at 20 breaths/min in patients with heart failure, whether expressed in absolute units (P = 0.005) or percentage of total power (P = 0.03).
4. On standing, controlled breathing in patients with heart failure produced less change in high-frequency power (P = 0.054), but the low-frequency/high-frequency ratio at lower respiratory rates was reduced (P = 0.05). In normal subjects, as expected, respiratory rate had a highly significant effect on high-frequency power. Also, in normal subjects there was the expected increase in heart rate low-frequency power (P = 0.04) moving from supine to standing with an increase in the low-frequency/high-frequency ratio (P = 0.003), while in the patients with heart failure this was absent, reflecting blunted cardiovascular reflexes.
5. Systolic blood pressure low- and high-frequency components and their ratio were significantly affected by respiration (P &gt; 0.03) and change in posture (P &gt; 0.03) in both patients with heart failure and normal subjects, with a significant increase in the low-frequency/high-frequency ratio (P = 0.03) on standing in patients with heart failure, indicating that autonomic modulation of blood pressure is still operating in heart failure.
6. Thus, respiratory rate and changes in posture have a significant effect on measurements derived from spectral analysis of heart rate and blood pressure variability. Studies that use power spectral analysis as a measure of sympatho-vagal balance should control for these variables.
Serological Response to Helicobacter Pylori in Gastric and Non—Gastric Cancer
Authors: Menegatti Marcello , Vaira Dino , Holton John , Miranda Fernanda , Ricci Chiara , Gusmaroli Riccardo , Ainley Colin , Miglioli Mario , Barbara Luigi 
Published: August 2015

1. We aimed to evaluate the seroprevalence of Helicobacter pylori (H. pylori) in gastric cancer, non-gastric cancer and outpatients by ELISA and isoelectric focusing, and to compare histology and serology for H. pylori in gastric cancer and outpatients.
2. In 124 patients with gastric cancer, 78 patients with non-gastric cancer and 110 outpatients, H. pylori seroprevalence was assessed by ELISA and isoelectric focusing. Gastric cancer and outpatients underwent endoscopy with biopsies.
3. Seroprevalence by ELISA was significantly higher in gastric cancer compared with non-gastric cancer (84% versus 56%, P &lt; 0.001) but not with outpatients (84% versus 74%). Iso-electric focusing detection of H. pylori was comparable to ELISA: 85, 51 and 75% in gastric cancer, non-gastric cancer and outpatients respectively. Oligoclonal iso-electric focusing was significantly more frequent in gastric cancer compared with non-gastric cancer and outpatients: 69% versus 45 and 46% respectively, P &lt; 0.01. The reliability of H. pylori detection by antral biopsy was significantly lower in gastric cancer compared with outpatients: 36% versus 74% (P &lt; 0.001). In gastric cancer, ELISA and iso-electric focusing were significantly more reliable than histology in H. pylori detection (84 and 85% versus 36% respectively) (P &lt; 0.001).
4. Serological immune response to H. pylori in gastric cancer, non-gastric cancer and outpatients seems different both quantitatively and qualitatively; serology was more reliable than histology in detection of H. pylori in gastric cancer.
Mitochondrial Protein Content and in Vivo Synthesis Rates in Skeletal Muscle from Critically Ill Rats
Authors: Rooyackers Olav E. , Kersten Alexande R H. , Wagenmakers Anton J. M. 
Published: August 2015

1. Recently we reported decreased activities of two mitochondrial marker enzymes (citrate synthase and cytochrome c oxidase) in skeletal muscle from a rat model of critical illness (zymosan injection). In the present study we investigated (i) whether these decreases in enzyme activity reflect a reduction in mitochondrial content and (ii) whether this potential reduction in mitochondrial content was the result of decreased mitochondrial protein synthesis rates.
2. Mitochondrial protein content was calculated from the activities of cytochrome c oxidase in whole-muscle homogenates and purified mitochondria. Synthesis rates of mitochondrial protein in vivo were studied by measuring the incorporation of [3H]phenylalanine into mitochondrial protein using the flooding dose technique.
3. Mitochondrial protein content was reduced to 54% of that measured in the pair-fed rats and to 71% of that measured in control rats fed ad libitum 2 days after the zymosan treatment The decreased mitochondrial protein content observed 2 days after zymosan challenge was preceded by a reduced rate of synthesis of mitochondrial protein 16 h after treatment. Both changes were of greater magnitude than the general muscle wasting and the decreased rate of synthesis of mixed protein observed in the zymosan-treated rats.
4. We conclude that the acute phase of critical illness in zymosan-treated rats is characterized by a substantial reduction in muscle mitochondria that is at least in part caused by a decreased rate of synthesis of mitochondrial protein. This derangement in mitochondrial protein metabolism may be related to the impaired muscle function observed during and after critical illness.
Chronic Sodium-Potassium-ATPase Inhibition with Ouabain Impairs Renal Haemodynamics and Pressure Natriuresis in the Rat
Authors: Kurashina Toshiaki , Kirchner Kent A. , Granger Joey P. , Patel Ami R. 
Published: August 2015

1. Chronic Na+,K+-ATPase inhibition with ouabain induces hypertension in the rat. To examine the role of the kidney in this process, the effect of changes in renal perfusion pressure on glomerular filtration rate, renal blood flow and urinary sodium excretion were determined in rats treated intraperitoneally with ouabain (27.8 μg day−1 kg−1 body weight) or vehicle for 6 weeks.
2. After ouabain administration, baseline mean arterial pressure was significantly higher (P &lt; 0.05) in ouabain-treated rats (151 ± 2 mmHg; n = 9) than in control rats (116 ± 4 mmHg; n = 8).
3. At equivalent renal perfusion pressures, glomerular filtration rate was significantly lower (P &lt; 0.05) in ouabain-treated rats compared with control rats. Glomerular filtration rate was 721 ± 73μl/min at 150 mmHg, and fell significantly to 322 ± 64 μl/min at 100 mmHg. In the control group, glomerular filtration rate was well autoregulated. The glomerular filtration rate autoregulatory index was calculated to determine the ability to maintain glomerular filtration rate during changes in renal perfusion pressure (0 reflects perfect autoregulation; &gt;1 reflects the absence of autoregulation). This index was greater in the ouabain group than in the control group (1.54 ± 0.2 compared with 0.29 ± 0.2; P &lt; 0.05). Renal blood flow showed a similar pattern.
4. Absolute urinary sodium excretion rate was less in ouabain-treated rats than in control rats at equivalent renal perfusion pressures. The slope of the relationship between absolute urinary sodium excretion rate and renal perfusion pressure was greater (P &lt; 0.05) in the control group than in the ouabain group (309.1 ± 57.1 compared with 82.1 ± 14.8 μmol min−1 mmHg−1).
5. Thus, chronic inhibition of Na+,K+-ATPase induces less efficient autoregulation of glomerular filtration rate and renal blood flow as well as a rightward shift in the pressure natriuresis relationship, such that a 25–30 mmHg higher renal perfusion pressure is necessary to excrete any given sodium load. These abnormalities may contribute to the development and maintenance of hypertension in this model.