bluuebunny/crossref_metadata_2025 huggingface dataset:
Microdialysis assessment of local adipose tissue lipolysis during β-adrenergic stimulation in upper-body-obese subjects with type II diabetes
Authors: BLAAK Ellen E. , KEMERINK Gerrit J. , PAKBIERS Marie Therese W. , WOLFFENBUTTEL Bruce H. R. , HEIDENDAL Guido A. , SARIS Wim H. M.
Published: August 2015

The present study was designed to investigate indicators of abdominal adipose tissue lipolysis (microdialysis), and subcutaneous adipose tissue blood flow and whole-body lipolysis, in obesity-associated type II diabetes during overnight-fasted conditions (baseline) and during intravenous infusion of the non-selective β-agonist isoprenaline. Basal subcutaneous adipose tissue blood flow and isoprenaline-induced increases in adipose tissue blood flow were not signifcantly different between subjects with type II diabetes and non-obese, non-diabetic controls. Adipose tissue interstitial glycerol concentrations were significantly higher in subjects with type II diabetes compared with controls (P< 0.01), and during isoprenaline infusion there was a decrease in interstitial glycerol in both groups (P< 0.001). Arterial glycerol concentrations were higher in subjects with type II diabetes compared with controls (P< 0.05), whereas the increases in arterial glycerol concentration in response to isoprenaline infusion were of a similar magnitude in the two groups. Estimated subcutaneous adipose tissue glycerol release was not significantly different between the groups (controls and subjects with type II diabetes: baseline, -129±32 and -97±72 μmol·min-1·100 g-1 adipose tissue respectively; isoprenaline, -231±76 and -286±98 μmol·min-1·100 g-1 respectively). Values for fat oxidation were not significantly different between groups, whereas the isoprenaline-induced increase in fat oxidation tended to be less pronounced in subjects with type II diabetes compared with controls (0.022±0.008 and 0.038±0.003 g/min respectively; P = 0.058). Thus estimated basal subcutaneous adipose tissue glycerol release, expressed per unit of fat mass, is not different in controls and in subjects with type II diabetes. Additionally, the isoprenaline-induced increases in indicators of local abdominal subcutaneous adipose tissue, systemic lipolysis and abdominal adipose tissue blood flow responses were comparable in obese subjects with type II diabetes and in controls. The last two findings contrast with previous data from obese subjects, indicating that the regulation of lipolysis may differ in obesity and obesity-associated type II diabetes.
Effects of branched-chain-enriched amino acids and insulin on forearm leucine kinetics
Authors: ZANETTI Michela , BARAZZONI Rocco , KIWANUKA Edward , TESSARI Paolo
Published: August 2015

Although amino acid mixtures enriched in branched-chain amino acids (BCAA) and deficient in aromatic amino acids (AAA) are often used together with insulin and glucose in clinical nutrition, their physiological effects on muscle protein anabolism are not known. To this aim, we studied forearm leucine kinetics in post-absorptive volunteers, before and after the systemic infusion of BCAA-enriched, AAA-deficient amino acids along with insulin and the euglycaemic clamp. The results were compared with the effects of insulin infusion alone. A compartmental leucine forearm model was employed at steady state. Hyperaminoacidaemia with hyperinsulinaemia (to ≈ 80–100 μ-units/ml) increased the leucine plasma concentration (+70%; P< 0.001), inflow into the forearm cell (+150%; P< 0.01), disposal into protein synthesis (+100%; P< 0.01), net intracellular retention (P< 0.01), net forearm balance (by ≈ 6-fold; P< 0.01) and net deamination to α-ketoisocaproate (4-methyl-2-oxopentanoate) (+9%; P< 0.05). Leucine release from forearm proteolysis and outflow from the forearm cell were unchanged. In contrast, hyperinsulinaemia alone decreased plasma leucine concentrations (-35%; P< 0.001) and leucine inflow (-20%; P< 0.05) and outflow (-30%; P< 0.01) into and out of forearm cell(s), it increased net intracellular leucine retention (P< 0.03), and it did not change leucine release from forearm proteolysis (-20%; P = 0.138), net leucine deamination to α-ketoisocaproate, leucine disposal into protein synthesis or net forearm protein balance. By considering all data together, leucine disposal into protein synthesis was directly correlated with leucine inflow into the cell (r = 0.71; P< 0.0001). These data indicate that the infusion of BCAA-enriched, AAA-deficient amino acids along with insulin is capable of stimulating forearm (i.e. muscle) protein anabolism in normal volunteers by enhancing intracellular leucine transport and protein synthesis. These effects are probably due to hyperaminoacidaemia and/or its interaction with hyperinsulinaemia, since they were not observed under conditions of hyperinsulinaemia alone.
Oximetry spectral analysis in the diagnosis of obstructive sleep apnoea
Authors: ZAMARRÓN C. , ROMERO P. V. , RODRIGUEZ J. R. , GUDE F.
Published: August 2015

Using spectral analysis of oximetry data, we prospectively evaluated the validity of this methodology in patients clinically suspected of suffering from obstructive sleep apnoea (OSA). A total of 233 outpatients were studied. Nocturnal oximetry was performed simultaneously with conventional polysomnography for all participants. The power density of oxygen saturation was analysed using Fast-Fourier transformation of the oximetric signal. Nocturnal oximetry test results were considered as abnormal (suspicion of OSA) if a peak in the spectrum between the period boundaries 30 and 70 s was observed. A normal test result was defined as the absence of the 30–70 s peak from the spectrum. Single-blind evaluation was performed by three independent observers, and agreement of two or more of these was considered definitive. The peak amplitude and the ratio of the area enclosed in the 30–70 s peak to the total area of the spectrum (rS) were measured. The presence of a peak has a sensitivity of 78%, a specificity of 89%, a positive predictive value of 89% and a negative predictive value of 78%. Apnoea–hypopnoea indexes were correlated significantly with peak amplitude (r = 0.74; P< 0.001) and with rS (r = 0.69; P< 0.001). For a peak amplitude threshold of 0.7%2, the sensitivity was 94% and the specificity was 65% for OSA diagnosis. Using a threshold for rS of 0.15, the sensitivity was 91% and the specificity was 67%. Thus the spectral analysis of nocturnal oximetry and identification of a peak at 30–70 s could be useful as a diagnostic technique for OSA subjects.
Is proteinuric pre-eclampsia a different disease in primigravida and multigravida?
Authors: BARDEN Anne E. , BEILIN Lawrence J. , RITCHIE Jackie , WALTERS Barry N. , GRAHAM Dorothy , MICHAEL Constantine A.
Published: August 2015

This study aimed to identify if the clinical features of proteinuric pre-eclampsia or the biochemical markers of endothelial dysfunction associated with this syndrome are altered according to parity in a direction that would suggest a different pathophysiology. Groups of 27 primigravid and 35 multigravid women with pre-eclampsia (defined as blood pressure > 140/90 mmHg and 2+ proteinuria) were studied ante-partum, and at 6 weeks and 6 months post-partum. Clinical markers of severity of pre-eclampsia, including blood pressure, markers of renal, hepatic and coagulatory function, and biochemical markers of endothelial dysfunction were measured. Fetal outcome was assessed by birthweight and birthweight percentile. Ante-partum systolic blood pressure was 10 mmHg higher in the primigravida, and this difference was independent of age and anti-hypertensive medication. Analysis of systolic blood pressure before and after delivery showed the primigravid women to have elevated systolic blood pressure over the whole time period (P< 0.01). The primigravid women had more severe hepatic dysfunction, with elevated aspartate aminotransferase levels, but plasma creatinine, proteinuria, platelet counts and haematocrit were similar, indicating that renal and coagulatory function and plasma volume were affected to the same extent in the two groups and were independent of parity. Birthweight was similar in the two groups, and the percentage of infants weighing less than the 10th centile for gestation was also similar. Biochemical markers of endothelial dysfunction, assessed by measuring the urinary prostacyclin metabolite 2,3-dinor-6-oxo-prostaglandin F1α and plasma endothelin 1, did not differ according to parity. There were no differences in a number of other biochemical markers of pre-eclampsia, including plasma albumin, uric acid, triacylglycerol, and total, low-density lipoprotein and high-density lipoprotein cholesterol. Basophil, monocyte and lymphocyte counts were elevated before delivery in primigravid women with pre-eclampsia. The differences in lymphocyte counts persisted post-partum. Further studies are required to clarify the role, if any, of monocytes, basophils and lymphocytes in the pathophysiology of pre-eclampsia. In conclusion, the elevated systolic blood pressure and raised aspartate aminotransferase levels observed in primigravida suggest a more severe form of pre-eclampsia. The lack of differences in birthweight and other biochemical and endothelial markers of severity of pre-eclampsia do not suggest a different pathophysiology; however, the persistently higher white cell counts in the primigravid pre-eclamptics are of interest, and might reflect differences in immune responses in the two groups. We suggest that studies of the pathophysiology of pre-eclampsia should include multigravida, as long as there is adequate post-partum follow-up to exclude underlying disease.
Statistical method for the estimation of cerebral blood flow using the Kety–Schmidt technique
Authors: MATTHEWS J. N. S. , MATTHEWS D. S. F. , EYRE J. A.
Published: August 2015

The Kety–Schmidt technique for the measurement of cerebral blood flow (CBF) has been in use for many years, but efficient statistical methods for producing estimates of CBF have received little attention. This paper proposes simple statistical models for this problem and explores their properties using data from a recent study of severe head injury in children. The method, which can readily be implemented on a personal computer, allows the uncertainty in the estimate of CBF to be quantified.
Reproducibility of methods for assessing baroreflex sensitivity in normal controls and in patients with chronic heart failure
Authors: DAVIES L. Ceri , FRANCIS Darrel P. , JURÁK Pavel , KÁRA Tomas , PIEPOLI Massimo , COATS Andrew J. S.
Published: August 2015

Baroreflex sensitivity (BRS) conveys useful prognostic information in patients with heart disease, yet methods for its quantification suffer from poor reproducibility and test failure in some patients with heart failure. We set out to compare the short-term reproducibility and success rate of four different methods of assessing BRS in normal subjects and patients with chronic heart failure (CHF). A total of 31 patients with CHF and 18 normal controls underwent BRS testing using four techniques: (1) bolus phenylephrine (BRSPhe), (2) α-index in both low- and high-frequency bands (BRSαLF and BRSαHF respectively), (3) the sequence method (BRSSeq), and (4) a new 0.1 Hz controlled-breathing, time-domain analysis method (BRSCbr). Each subject underwent two test episodes with each method on the same day. The average values for BRS in patients and controls respectively were: BRSPhe, 4.4 (±4.4) ms/mmHg and 19.8 (±11.5) ms/mmHg; BRSαLF, 5.6 (±4.1) ms/mmHg and 15.4 (±5.0) ms/mmHg; BRSαHF, 7.1 (±7.0) ms/mmHg and 25.1 (±8.3) ms/mmHg; BRSSeq, 7.7 (±6.3) ms/mmHg and 22.5 (±8.4) ms/mmHg; BRSCbr, 6.6 (±5.9) ms/mmHg and 22.8 (±10.8) ms/mmHg. The coefficients of variation (S.D. of the difference in repeated values divided by mean) in patients and controls respectively were: BRSPhe, 85.6% and 52.2%; BRSαLF, 65.9% and 33.7%; BRSαHF, 99.7% and 52.1%; BRSSeq, 30.7% and 40.4%; BRSCbr, 30.7% and 19.6%. The numbers of test failures in patients were: BRSPhen, 15; BRSαLF, 7; BRSαHF, 5; BRSSeq, 14; BRSCbr, 1. Of the four techniques assessed for measuring BRS, the controlled breathing time-domain method yielded the best reproducibility and lowest failure rate in controls and in patients with CHF.
Metabolism of lactose-[13C]ureide and lactose-[15N,15N]ureide in normal adults consuming a diet marginally adequate in protein
Authors: JACKSON A. A. , BUNDY R. , HOUNSLOW A. , MURPHY J. L. , WOOTTON S. A.
Published: August 2015

Oral lactose-ureide is resistant to human digestive enzymes, but is fermented by the colonic microflora. Nine normal adults consuming a diet which provided 36 g of protein/day were given oral doses of lactose-[13C]ureide and lactose-[15N,15N]ureide. The appearance on breath of 13CO2 derived from lactose-[13C]ureide was followed for 48 h. The fate of 15N derived from lactose-[15N,15N]ureide was determined by measuring the recovery of 15N in stools and urine in various forms. About 80% of the label given as lactose-[13C]ureide was recovered on the breath, and about 80% of label given as lactose-[15N,15N]ureide was not recovered in stool, indicating that 80% of the dose was completely fermented. At least 5% of the labelled urea was absorbed and excreted as the intact molecule. Of the 15N derived from lactose-[15N,15N]ureide and available for further metabolic interaction, 67% was retained and 33% was excreted in urine. The time taken for [15N,15N]urea to appear in urine was similar for all subjects, but the appearance of either 13CO2 on the breath or [15N,14N]urea in urine varied. It is concluded that the hydrolysis of the sugar–urea bond may reflect oro–caecal transit time, but that other factors related to colonic bacterial metabolism determine the duration and extent of hydrolysis of urea by urease enzymes. Lactose-ureide can be used to probe the metabolic activity of the colonic microflora in normal individuals.
Small-intestinal mucosal protein synthesis and whole-body protein turnover in alcoholic liver disease
Authors: NAKSHABENDI I. M. , DOWNIE S. , RUSSELL R. I. , RENNIE M. J.
Published: August 2015

We used stable-isotope-labelled amino acids to measure the effects of alcoholic liver disease (ALD) on whole-body protein turnover and small-intestinal mucosal protein synthesis. Groups comprising eight patients with ALD and eight healthy control subjects were studied. They received primed, continuous intravenous infusions of L-[1-13C]leucine after an overnight fast; after 4 h, duodenal biopsies were obtained via endoscopy. Protein synthesis was calculated from protein labelling relative to intracellular leucine enrichment. Rates of duodenal mucosal protein synthesis were 2.58±0.32%·h-1 (mean±S.D.) in the normal subjects and 2.04±0.18%·h-1 in the ALD patients (P< 0.003), despite the fact that the protein synthetic capacity (μg of RNA/mg of protein) was higher in ALD patients (160±14 compared with 137±6 μg/mg; P < 0.003). The mucosal cell size (protein/DNA ratio) was lower in ALD patients (9.23±0.91 compared with 13±2.2 μg/mg; P< 0.002). Although the mean rates of whole-body protein turnover were not significantly different between the two groups (204±18 and 196±44 μmol leucine·h-1·kg-1 for ALD and control subjects respectively), there was, in the ALD patients, an inverse relationship between the rate of small-intestinal mucosal protein synthesis and the severity of ALD; furthermore, there was a direct relationship between the rate of whole-body protein turnover and the severity of ALD. Thus there was an inverse relationship between the rate of small-intestinal mucosal protein synthesis and the rate of whole-body protein turnover in ALD patients, which was not seen in the normal subjects.
Analgesic effects of adenosine in Syndrome X are counteracted by theophylline: a double-blind placebo-controlled study
Authors: ERIKSSON Björn E. , SADIGH Bita , SVEDENHAG Jan , SYLVÉN Christer
Published: August 2015

It has been proposed that adenosine mediates ischaemic pain in humans. Patients with cardiac Syndrome X are hypersensitive to potential pain stimuli, including adenosine. On the other hand, recent findings suggest that low-dose adenosine infusion may have analgesic effects. Our aim was to test two hypotheses: (1) that the analgesic effect of adenosine is peripheral in origin, and (2) that part of the hypersensitivity to pain of patients with cardiac Syndrome X results from a disturbed mechanism of adenosine analgesia. A total of 12 female Syndrome X patients and eight healthy age-matched female controls were studied in a randomized, double-blind and placebo-controlled study. Adenosine (70 μg/min) or placebo was infused into the forearm via an intra-arterial catheter. After 15 min of infusion, a tourniquet on the upper arm was inflated to 225 mmHg to ensure arterial occlusion. The patient then carried out dynamic handgrip work at 60 Hz. Pain or discomfort in the forearm was estimated continuously according to the Borg CR-10 scale. After the first test, theophylline was infused for 10 min intravenously at a dose of 5 mg/kg body weight. The ischaemic forearm test was then repeated. On a second occasion, the procedure was repeated with the opposite treatment (adenosine/placebo). Only six of 12 Syndrome X patients completed the protocol because of pain during the catheterization procedure or an inability to establish an intra-arterial line. The time to onset of pain in the working, ischaemic forearm was greater for subjects treated with adenosine than for those treated with placebo, both in those Syndrome X patients who tolerated catheterization (49±27 s compared with 32±18 s; P< 0.03) and in healthy controls (40±19 s compared with 16±8 s; P< 0.02). The time to maximum pain, limiting ischaemic work, was also greater with adenosine pretreatment both in Syndrome X patients (137±28 s compared with 106±28 s; P< 0.03) and in healthy controls (109±31 compared with 82±18 s; P< 0.01). After infusion of theophylline there was no difference between adenosine and placebo in either group. Intra-arterially infused adenosine had similar peripheral analgesic effects on experimentally induced muscular ischaemia in those female Syndrome X patients who tolerated intra-arterial catheterization and in healthy controls. Thus adenosine analgesia is counteracted by theophylline, suggesting that the effect is mediated by membrane-bound peripheral adenosine receptors.
Influence of muscle temperature on the contractile properties of the quadriceps muscle in humans with spinal cord injury
Authors: GERRITS H. L. , DE HAAN A. , HOPMAN M. T. E. , VAN DER WOUDE L. H. V. , SARGEANT A. J.
Published: August 2015

Low muscle temperature in paralysed muscles of individuals with spinal cord injury may affect the contractile properties of these muscles. The present study was therefore undertaken to assess the effects of increased muscle temperature on the isometric contractile properties of electrically stimulated paralysed quadriceps muscles. When muscle temperature at a depth of 3 cm was increased from ∼32 °C to ∼36 °C by ultra-short-wave application, the half-relaxation time shortened and low-frequency force responses became less fused, but the maximal rate of increase in force remained unchanged. Heating had no effect upon either force decline or slowing of relaxation during fatiguing contractions. The force–frequency relationship of the paralysed quadriceps muscle was shifted to the right after the muscle was heated. Despite this shift, however, the relationship still resembled that in muscles of non-paralysed individuals, probably due to the unexplained high twitch forces. These results indicate that reduced muscle temperature in spinal-cord-injured individuals may lead to an underestimation of the changes in contractile properties in terms of relaxation rate or the degree of fusion with low-frequency stimulation. In addition, the force–frequency relationship of paralysed muscles does not accurately reflect the magnitude of these changes, even when the muscle is heated, and should therefore be treated with caution.
Reduced baroreflex sensitivity in elderly humans is not due to efferent autonomic dysfunction
Authors: O'MAHONY D. , BENNETT C. , GREEN A. , SINCLAIR A. J.
Published: August 2015

A progressive decline in baroreflex sensitivity (BRS) is a characteristic feature of human aging, the basis of which is poorly understood. The purpose of the present study was to determine whether alterations in efferent baroreflex function might contribute to the age-related decrease in BRS. We studied 10 healthy young (mean age 30.5 years; age range 22–40 years; six male) and 10 healthy elderly (mean age 70.7 years; age range 67–75 years; five male) volunteers. We tested efferent cardiac vagal function using the bradycardiac response to the cold face test, and efferent sympathetic function using heart rate and blood pressure responses to four stress tests: (i) low-level cognitive stress, (ii) high-level cognitive stress, (iii) hand immersion in ice water (cold pressor test) and (iv) isometric sustained hand-grip. Haemodynamic responses to these stresses are mediated via efferent baroreflex pathways, whereas the afferent components of each reflex response are independent of afferent baroreflex pathways. BRS was measured from simultaneous Finapres-derived continuous blood pressure and digital ECG R–R interval data using the sequence analysis paradigm. As expected, BRS was significantly reduced in the elderly group (7.29±0.74 ms/mmHg; mean±S.E.M.) compared with the young group (13.84±1.13 ms/mmHg; P < 0.001). However, neither the bradycardiac responses to the cold face test nor the efferent sympathetically mediated heart rate/blood pressure responses to the stress test battery were significantly different between the young and elderly groups. We conclude that the age-related decrease in BRS is not attributable to impairments in the efferent sympathetic or parasympathetic system components of the baroreceptor reflex pathway.
Basal and exercise-induced skeletal muscle blood flow is augmented in type I diabetes mellitus
Authors: SKYRME-JONES R. Andrew P. , BERRY Karen L. , O'BRIEN Richard C. , MEREDITH Ian T.
Published: August 2015

Hyperaemia occurs early in the renal and retinal microcirculation of patients with type I (insulin-dependent) diabetes mellitus, and may be critical in the development of nephropathy and retinopathy. We therefore sought to determine whether resting and exercise-induced hyperaemia was also apparent in the skeletal muscle circulation of young subjects with type I diabetes. Blood flow was assessed by venous occlusion plethysmography in 18 diabetic (DM) subjects and 20 matched controls. Exercise entailed 2 min of isotonic exercise against no load. Endothelium-dependent and -independent vasodilator function was assessed following intra-arterial infusion of acetylcholine and sodium nitroprusside respectively. Forearm blood flow (FBF) was higher in DM subjects than in controls (3.3±0.3 and 2.2±0.2 ml·min-1·100 ml-1 forearm respectively; P < 0.005). This was not due to differences in forearm or body size, blood pressure, heart rate, lipid status or glycaemic control. Peripheral insulin levels were higher in DM subjects than in controls (48.5±8 and 15.5±1.5 μ-units/ml respectively; P < 0.005). Resting FBF was closely correlated with insulin levels (r2 = 0.4; P < 0.005). Parameters of exercise-induced hyperaemia [including peak flow (16.4±1.4 and 12.0±0.7 ml·min-1·100 ml-1 forearm in DM and control subjects respectively; P < 0.01) and the volume repaid to the forearm at 5 min post-exercise (32.1±3.1 and 23.1±1.4 ml·100 ml-1 forearm respectively; P < 0.05)] were also significantly greater in DM subjects, even when differences in resting FBF were taken into account. Peak hyperaemic blood flow and the volume repaid at 5 min were also related to insulin levels (r2 = 0.16; P < 0.05 and r2 = 0.27; P < 0.005 respectively). The vasodilator response to acetylcholine was reduced in DM subjects (P < 0.05; analysis of variance), and the slope of this dose–flow relationship was inversely related to insulin levels (r2 = 0.2; P < 0.05). These data show that both resting and exercise-induced skeletal muscle blood flow are augmented in young patients with type I diabetes, possibly due to the vasodilatory effect of increased insulin levels. Diminished vasodilator responses to acetylcholine may also, in part, be a consequence of insulin-augmented resting muscle blood flow.
Enzyme load in pancreatic acinar cells is increased in the early stages of acute pancreatitis induced by duct obstruction in rats
Authors: URUÑUELA Aránzazu , MANSO Manuel A. , PINTO Rosa M , ORFAO Alberto , DE DIOS Isabel
Published: August 2015

Trypsinogen and amylase content has been analysed by flow cytometry in individual pancreatic cells from rats with acute pancreatitis induced by pancreatic duct obstruction, from the earliest stages to 48 h after obstruction. Parallel morphological studies of the pancreas by electron microscopy and analysis of various parameters for the diagnosis of pancreatitis will allow research into the possible relationship between intracellular enzyme load and the severity of pancreatitis. Progressive increases in amylase activity in ascites and plasma, the volume of ascites, haematocrit, vacuolization, oedema and macrophage infiltration were observed between 1.5 h and 12 h after duct obstruction. A progressive increase in enzyme content was also observed in individual acinar cells at this stage. Interestingly, the larger increase was for trypsinogen, so that the trypsinogen/amylase ratio was significantly increased in all acinar cells by 12 h after duct obstruction. This represents a risk factor for the development of pancreatitis. Sections of pancreas taken from rats that had duct obstruction for 48 h showed massive dilatation and disorganization of the endoplasmic reticulum, focal apoptosis and necrosis. These severe alterations would affect enzyme synthesis, as reflected by the significant decrease in the intracellular enzyme load observed at this stage. However, not all acinar cells were affected equally by the damage induced by pancreatitis: R1 cells appeared to be more sensitive than R2 cells. In conclusion, intracellular accumulation of digestive enzymes occurs at early stages of pancreatitis, and this effect is proportionally greater for trypsinogen, a finding that could explain the degree of severity achieved in the course of pancreatitis.
Cerebral oxygenation at high altitude and the response to carbon dioxide, hyperventilation and oxygen
Authors: IMRAY C. H. E. , BREAREY S. , CLARKE T. , HALE D. , MORGAN J. , WALSH S. , WRIGHT A. D.
Published: August 2015

Cerebral oxygenation is likely to be of critical importance in determining function at high altitude. The present study has used the technique of near-IR spectroscopy to monitor changes in cerebral regional oxygenation in response to inhaled carbon dioxide, hyperventilation and supplementary oxygen on ascent to 4680 m over 3 days. At sea level, inhaled CO2 resulted in a significant rise in cerebral regional oxygenation [from mean 69.6% (S.D. 2.4% to 71.1±2.3%; means±S.D.; P < 0.001). At 4680 m, CO2 increased regional cerebral oxygenation (63.8±2.5% to 65.9±2.2%; P < 0.001) and also increased peripheral oxygen saturation (75.1±6.1% to 83.6±4.0%; P < 0.001). Voluntary hyperventilation resulted in improved peripheral oxygen saturation at 2770 m, 3650 m and 4680 m, whereas cerebral regional oxygenation was reduced at sea level and at 2770 m, unchanged at 3650 m and increased at 4680 m. Supplementary oxygen (6 1itres/min) at 4680 m resulted in greater improvements in peripheral oxygen saturation (76.7±7.9% to 98.1±1.5%; P < 0.001) and cerebral regional oxygenation (64.6±3.3% to 70.6±2.9%; P < 0.001) than were found with CO2 or hyperventilation. We conclude that attempts to increase CO2 inhalation or ventilation at high altitude are likely to be beneficial for cerebral oxygenation in the short term.
Noradrenaline and Nω-monomethyl-L-arginine (L-NMMA): effects on haemodynamics and regional blood flow in healthy and septic sheep
Authors: BOOKE M. , HINDER F. , MCGUIRE R. , TRABER L. D. , TRABER D. L.
Published: August 2015

This prospective, non-randomized, controlled experimental study looks at the effects of NΩ-monomethyl-l-arginine (l-NMMA) on haemodynamics, oxygen transport and regional blood flow in healthy and septic sheep, and compares these effects with those of noradrenaline (NA; norepinephrine). All sheep were chronically instrumented. Six sheep received l-NMMA (7 mg·kg-1·h-1), six sheep received NA, and seven sheep received the carrier alone (0.9% NaCl). The NA dosage was continuously and individually adjusted to achieve the same increase in blood pressure as observed in matched sheep of the l-NMMA group (non-septic phase). Treatment was discontinued after 3 h. Sepsis was initiated and maintained by a continuous infusion of live Pseudomonas aeruginosa. After 24 h of sepsis, the sheep were again challenged over a treatment period of 3 h with their previously assigned drug (septic phase). During the non-septic phase of the experiment, NA and l-NMMA both caused an increase in mean arterial pressure (MAP) through vasoconstriction. Ater 24 h of sepsis, all sheep developed a hyperdynamic circulatory state. While l-NMMA caused an increase in MAP through intense vasoconstriction, NA caused MAP to increase through a further elevation of the cardiac index. The NA dosage needed was significantly higher in the septic phase compared with the non-septic phase, reflecting a reduced vascular responsiveness to catecholamines during sepsis. Renal blood flow remained unchanged during either treatment in both the non-septic and the septic phases. Nevertheless, urine output increased during NA treatment in both the non-septic and the septic phases, while l-NMMA caused urine output to increase only under septic conditions.
Steroid hormone receptor expression and action in bone
Authors: BLAND Rosemary
Published: August 2015

The skeleton is a complex tissue, and hormonal control of bone remodelling is elaborate. The important role that steroid hormones play in bone cell development and in the maintenance of normal bone architecture is well established, but it is only relatively recently that it has become possible to describe their precise mechanism of action. This review focuses not only on the steroid hormones (oestrogens, corticosteroids, androgens and progesterone), but also on related hormones (vitamin D, thyroid hormone and the retinoids), all of which act via structurally homologous nuclear receptors that form part of the steroid/thyroid receptor superfamily. By examining the actions of all of these hormones in vivo and in vitro, this review gives a general overview of the current understanding of steroid hormone action in bone. In addition, a comprehensive review of steroid hormone receptor expression in bone cells is included. Finally, the role that future developments, such as steroid hormone receptor knockout mice, will play in our understanding of steroid hormone action in bone is considered.
Albumin stimulates p44/p42 extracellular-signal-regulated mitogen-activated protein kinase in opossum kidney proximal tubular cells
Authors: DIXON Richard , BRUNSKILL Nigel J.
Published: August 2015

The presence of protein in the urine of patients with renal disease is an adverse prognostic feature. It has therefore been suggested that proteinuria per se may be responsible for the development of renal tubulo-interstitial scarring and fibrosis, and disturbances in tubular cell growth and proliferation. We have used the opossum kidney proximal tubular cell line to investigate the effects of albumin on cell growth. The effect of albumin on cell proliferation was investigated by cell counting and measurement of [3H]thymidine incorporation. We studied the effect of recombinant human albumin on the activity of p44/p42 extracellular-signal-regulated mitogen-activated protein kinase (MAP kinase) using an in vitro kinase assay, and immunoblotting with antibodies against active extracellular-signal-regulated kinase (ERK). The effects of the ERK inhibitor PD98059 were also examined. Recombinant human albumin was found to stimulate proliferation of opossum kidney cells in a dose-dependent manner, with maximal stimulation at a concentration of 1 mg/ml. In addition, recombinant human albumin activated ERK in a time-dependent (maximal after 5 min) and dose-dependent (maximal at 1 mg/ml) fashion. These effects on cell proliferation and ERK activity were inhibited by PD98059, and were not reproduced by ovalbumin or mannitol. The data therefore indicate that albumin is able to stimulate growth and proliferation of proximal tubular cells that is dependent on the ERK family of MAP kinases. The potential importance of this pathway in the development of renal disease is discussed.
Magnesium regulates hypoxia-stimulated apoptosis in the human placenta
Authors: GUDE N. M. , STEVENSON J. L. , MOSES E. K. , KING R. G.
Published: August 2015

Apoptosis (programmed cell death) in the human placenta is likely to play a major role in determining the structure and function of that organ. Fetal growth restriction (FGR) has been shown to be associated with increased levels of placental apoptosis. Altered regulation of apoptosis may play an important pathophysiological role in FGR. As reduced placental perfusion and reduced oxygenation are features of FGR, one aim of this study was to determine the effects of hypoxia on apoptotic activity, as assessed by DNA laddering, of placental tissue in vitro. In addition, levels of placental apoptosis may be affected by pharmacological agents routinely used in obstetric patient management. Thus an additional aim of this study was to determine the effects of several relevant pharmacological agents on the levels of DNA laddering during in vitro incubation of human placentae under hypoxic conditions. Incubation of normal placental explant tissue at 37 °C for 1–2 h under hypoxic conditions significantly increased placental DNA laddering compared with that in non-incubated tissue, whereas levels of DNA laddering during incubation for up to 2 h under normoxic conditions were not significantly higher than those in non-incubated tissue. The DNA laddering activity of placental explants after 2 h of incubation under hypoxic conditions was significantly increased with increased concentrations of magnesium, but remained unchanged by the inclusion of pethidine, aspirin, nifedipine, dexamethasone, heparin or indomethacin in the incubation mixture. These results suggest that hypoxia may stimulate apoptotic activity in cultured human placental tissues, and that hypoxia-stimulated placental apoptosis may be further increased by increasing the extracellular magnesium concentration.
Regulation of β-adrenoceptor-mediated relaxation of the rat aorta is modulated by endogenous ovarian hormones
Authors: CONDE María V. , MARÍN Jesús , FERNÁNDEZ-CRIADO Carmen , BALFAGÓ NGloria
Published: August 2015

The aim of this study was to assess the influence of the endogenous status of ovarian hormones on the relaxation induced by the β-adrenoceptor agonists isoprenaline (isoproterenol) and dobutamine in thoracic aorta segments, precontracted with noradrenaline, from age-matched (13-week-old) virgin (oestrus) and ovariectomized (OVX) prepubertal female Wistar rats. Isoprenaline-induced relaxation was decreased in intact aortic segments from OVX rats compared with that in segments from oestrus rats. Relaxation was significantly reduced by endothelium removal, 1 µmol/l propranolol or 100 µmol/l NG-nitro-l-arginine methyl ester (l-NAME). The β1-adrenoceptor agonist dobutamine induced less relaxation in intact arteries from oestrus rats than did isoprenaline, and dobutamine-induced relaxation was markedly less in intact segments from OVX compared with oestrus rats. This dobutamine-induced relaxation was abolished by endothelium removal, and reduced by 1 µmol/l propranolol, 100 µmol/l l-NAME or 1 µmol/l yohimbine. Cholera toxin (an activator of the stimulatory G-protein Gs) caused relaxation in intact arteries from oestrus rats; this relaxation was decreased by both deprivation of ovarian hormones and endothelium removal. Forskolin (a direct activator of the catalytic subunit of adenylate cyclase) and sodium nitroprusside (a nitric oxide donor and cGMP-dependent vasodilator agonist) induced similar endothelium-independent relaxation in arteries from both oestrus and OVX rats. These results suggest that the relaxation elicited by endothelial β-adrenoceptor activation in the rat thoracic aorta is impaired by deprivation of female ovarian hormones; this impairment is caused, at least in part, by decreases in both the endothelial release of NO and Gs function.
Sequential changes in plasma cytokine and endotoxin levels in cirrhotic patients with bacterial infection
Authors: WANG Sun-Sang , LEE Fa-Yauh , CHAN Che-Chang , LU Rei-Hwa , CHAO Yee , LIN Han-Chieh , WU Shwu-Ling , TSAI Yang-Te , LEE Shou-Dong
Published: August 2015

To delineate the clinical roles of plasma cytokine or endotoxin levels in the natural course of infection in patients with decompensated cirrhosis, 66 cirrhotic patients were studied within a 1.5-year period. Plasma levels of tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, IL-8 and endotoxin were determined on days 1, 4 and 7 after admission when hospital infection was suspected and 4 months later. A total of 24 patients (36.4%) were proven to be infected during hospitalization (group A), while 42 others were not infected (group B). Fever occurred in a very high proportion (22/24) of group A patients. Baseline levels of TNF-α (37.7±15.2 compared with 8.7±1.2 pg/ml; P < 0.01) and IL-6 (180.5±20.5 compared with 24.6±7.5 pg/ml; P < 0.0001) were higher in group A patients, while IL-1β, IL-8 and endotoxin levels were not significantly different between the two groups. For patients with hospital infection, IL-6 levels determined during the episode were significantly higher than baseline levels. Using IL-6 > 80 pg/ml as a baseline cut-off level to diagnose bacterial infection, the sensitivity, specificity and accuracy were 87.5, 100 and 95.5% respectively. The one-year cumulative probability of mortality (61.1% compared with 23.7%; P < 0.001) and of bacterial re-infection (72.2% compared with 18.4%; P < 0.0001) was higher in group A than in group B. Plasma TNF-α and IL-6 levels determined at 4 months were not different between the two groups. In conclusion, fever or elevated plasma IL-6 levels in patients with decompensated cirrhosis calls for early antibiotic treatment to prevent life-threatening bacterial infection. Bacterial infection is likely to recur in those patients with increased IL-6 levels, while severe episodes of infection occur in patients with increased TNF-α levels.
Indexed glomerular filtration rate as a function of age and body size
Authors: PETERS A. M. , HENDERSON B. L. , LUI D.
Published: August 2015

The conventional way in which to scale or index a measurement of glomerular filtration rate (GFR) is to express it in relation to body surface area (BSA). However, BSA may not be appropriate for infants and children because, as individuals increase in size, their relative BSA decreases. Several other whole-body variables have been suggested as alternatives, including extracellular fluid volume (vECF). The purpose of the present study was to compare BSA and vECF as variables against which to index GFR, and in particular to look at this comparison in children versus adults. A total of 130 patients (age range 1–80 years; 40 patients < 12 years) undergoing clinically indicated routine measurement of GFR using the bolus-injection single-compartment technique were included in the study. GFR was measured as the plasma clearance of [51Cr]EDTA as assessed from three peripheral venous blood samples taken between 2 and 4 h after injection of [51Cr]EDTA. Volume of distribution (Vd) was obtained by extrapolation of the clearance curve to zero time. GFR was scaled to a BSA of 1.73 m2. GFR and GFR/1.73 m2 were corrected to account for the assumption of a single compartment. The rate constant of the exponential between 2 and 4 h was also corrected to give GFR/litre ECF. GFR and GFR/1.73 m2 were both divided by GFR/litre ECF, to give vECF and vECF/1.73 m2 respectively. Weight per unit BSA increases as a linear function of BSA. vECF is always less than Vd, on average by about 30%. vECF increased as an exponential function of BSA and as a linear function of body weight. vECF/70 kg body weight was higher in children (16.2±3 litres) than adults (13.4±2.3 litres), but vECF/1.73 m2 was lower in children (9.7±1.7 litres) compared with adults (12.4±2 litres). vECV/1.73 m2 increased as a function of both age and BSA, but vECF/kg decreased. GFR/12.5 litres vECF was higher than GFR/1.73 m2 in children, but these values were similar in adults, with the ratio of these two forms of indexed GFR falling significantly with both age and BSA. Although this was not a normal population, but one with a wide range of renal function, GFR/vECF showed a strong inverse association with age, whereas for GFR/BSA the association was weak. In conclusion, these data provide further evidence that vECF is more valid physiologically for indexing GFR than is BSA, especially in children. Nevertheless, a GFR measurement in a child should ideally be expressed as a percentage of normal for that child's age. However, such normal values are not yet available.
Effects of inter-α-inhibitor and several of its derivatives on calcium oxalate crystallization in vitro
Authors: DEAN Caroline , KANELLOS Jerry , PHAM Hung , GOMES Maria , OATES Adrian , GROVER Phulwinder , RYALL Rosemary
Published: August 2015

The bikunin peptide chain of the protease inhibitor inter-α-inhibitor (∣α∣) has been reported to be an inhibitor of calcium oxalate (CaOx) crystallization, and hence has been proposed as having a role in CaOx kidney stone formation. However, further experimental evidence is required to assess if fragments of ∣α∣ other than bikunin may play a role in the regulation of crystallization events in stone formation. The aim of the present study was to assess the effects of ∣α∣ and several of its derivatives on CaOx crystallization in a seeded inorganic system and to compare these effects with those of a known inhibitor of crystallization, prothrombin. ∣α∣ was purified from a preparation of human plasma and fragmented by alkaline hydrolysis, and two of its peptide chains, bikunin and heavy chain 1 (H1), were purified further by HPLC. Their purity was confirmed by SDS/PAGE. Using Coulter counter and [14C]oxalate analysis and scanning electron microscopy, ∣α∣, its H1 chain and bikunin from urine and from plasma were shown to be relatively weak inhibitors of CaOx crystallization in vitro at expected physiological concentrations. It was concluded that members of the ∣α∣ family may not be as important in kidney stone formation as has been generally proposed, although further studies are required before a possible role for ∣α∣ and its fragments in stone formation can be unambiguously discounted.
S-Nitrosothiols: a class of nitric oxide-donor drugs
Authors: AL-SA'DONI Haitham , FERRO Albert
Published: August 2015

Nitric oxide (NO) was originally described as the principal endothelium-derived relaxing factor, but it is now known to subserve a variety of functions throughout the body, both physiological and pathophysiological. NO-donor drugs decompose in the body, by a variety of mechanisms, to generate NO. Such drugs have been used for many years in cardiovascular therapeutics, in particular the organic nitrates for the prevention and treatment of angina pectoris and sodium nitroprusside for the treatment of hypertensive emergencies. However, patients taking long-term nitrates often develop tolerance, and prolonged nitroprusside administration can give rise to cyanide accumulation in the body. Newer NO-donor drugs, in particular the S-nitrosothiols, offer advantages over the existing drugs, since they do not share these drawbacks, and initial small clinical studies suggest that they may be of benefit in a variety of cardiovascular disorders. Here we briefly review the chemistry and physiology of NO, and discuss the chemistry and clinical possibilities of the S-nitrosothiols.
Non-invasive measurement of stroke volume during exercise in heart failure patients
Authors: AGOSTONI Pier Giuseppe , WASSERMAN Karlman , PEREGO Giovanni B. , GUAZZI Marco , CATTADORI Gaia , PALERMO Pietro , LAURI Gianfranco , MARENZI Giancarlo
Published: August 2015

The objective of the present study was to determine the variability of the arterio–venous O2 concentration difference [C(a–v)O2] at anaerobic threshold and at peak oxygen uptake (VO2) during a progressively increasing cycle ergometer exercise test, with the purpose of assessing the possible error in estimating stroke volume from measurements of VO2 alone. We sampled mixed venous and systemic arterial blood every 1 min during a progressively increasing cycle ergometer exercise test and measured, in each blood sample, haemoglobin concentration and blood gas data. Ventilation, VO2 and CO2 uptake were also measured continuously. We studied 40 patients with normal haemoglobin concentrations and with stable heart failure due to ischaemic or idiopathic cardiomyopathy. Mean values (±S.D.) for C(a–v)O2 were 7.8±2.6, 13.0±2.4 and 15.0±2.7 ml/100 ml at rest, anaerobic threshold and peak VO2 respectively. The patients with heart failure were divided into classes according to their peak VO2. Classes A, B and C contained patients with peak VO2 values of > 20, 15–20 and 10–15 ml·min-1·kg-1 respectively. At anaerobic threshold, C(a–v)O2 was 12.3±1.3, 13.1±2.7 and 13.5±2.6 ml/100 ml for classes A, B and C respectively (class A significantly different from classes B and C; P < 0.05). At peak exercise C(a–v)O2 was 13.6±1.4, 15.6±2.5 and 15.4±3.2 ml/100 ml for classes A, B and C respectively (class A significantly different from classes B and C; P < 0.05). Stroke volume was estimated for each subject using the mean values of the measured C(a–v)O2 in each functional class and individual values of VO2 and heart rate using the Fick formulation. The average difference between the stroke volume estimated from mean C(a–v)O2 and that obtained using the patient's actual C(a–v)O2 value was 9.2±9.7, 1.0±8.8 and -0.2±6.1 ml at anaerobic threshold, and -1.9±11.3, 0.9±10.0 and -2.3±8.5 ml at peak exercise, in classes A, B and C respectively. Among the various classes, the most precise estimation of stroke volume was observed for class C patients. We conclude that stroke volume during exercise can be estimated with the accuracy needed for most purposes from measurement of VO2 at the anaerobic threshold and at peak exercise, and from population-estimated mean values for C(a–v)O2 in heart failure patients.