bluuebunny/crossref_metadata_2025 huggingface dataset:
Autonomic nerve function in children and adolescents with insulin‐dependent diabetes mellitus
Authors: Åman J. , Eriksson E. , Lideen J.
Published: April 2008

Autonomic nerve function was assessed in 67 insulin‐dependent diabetic children and adolescents and in 30 control subjects of the same age. The heart rate and blood pressure reactions to a deep breathing test (E/I ratio) and a tilt table test (acceleration and brake indices) were used. The E/I ratio, 1·54 +0·21, and the acceleration index, 25 ± 7·7, in the diabetic children were not significantly different from those of the control children, 1·51 ± 0·16 and 24 ± 7·5, respectively. Neither was any difference observed between the mean brake index values; 24·3 ± 14·6 vs 23·5 ± 7·5. However, the variance of the brake index in diabetic children was significantly higher than in control children (P< 0·005).

The brake index was negatively correlated to age in the healthy control children (r= ‐0·48, P <0·1). The acceleration index, but not the E/I ratio, also tended to be age related (r= ‐0·32, P<0·01 NS).

No correlation was observed between sex, glycaemic control or duration of diabetes and the autonomic nerve function. Neither were severe hypoglycaemic episodes in diabetic children related to the autonomic nerve function.

It is concluded that autonomic neuropathy is uncommon in diabetic children and adolescents and that age‐related index values should be used when autonomic nerve function is evaluated in children of different ages.
Central haemodynamics in patients with severe postural hypotension
Authors: Mehlsen J. , Haedersdal C. , Trap‐Jensen J.
Published: April 2008

Central haemodynamics in the supine and head‐up tilted positions were studied in 24 patients with severe postural hypotension with and without supine hypertension. Results were compared with those obtained in eight normotensive and eight untreated hypertensive controls.

In the supine position the patients had higher vascular resistances, lower stroke volumes and longer left ventricular ejection time indexes compared to controls, whereas left ventricular ejection fractions did not differ significantly. The patients with supine hypertension had significantly higher vascular resistance compared to those with supine normotension. The highest supine blood pressure levels were found in patients with multiple system atrophy.

During tilt, vascular resistance and heart rates were increased and stroke volumes and left ventricular ejection time indexes were decreased in the controls. The patients were unable to increase their vascular resistance, but increased their heart rate and decreased their left ventricular ejection time indexes to a degree similar to the controls. The reductions in stroke volume were smaller in the patients compared to the controls. Changes in haemodynamics in response to head‐up tilting did not differ significantly between patients with supine hypertension and supine normotension.

It is concluded that patients with postural hypotension have higher supine vascular resistance and are unable to contract peripheral arteries and arterioles during head‐up tilting. Contractility of the left ventricle is preserved and the baroreceptors are partially intact. Postural hypotensive patients with supine hypertension differ from those with supine normotension only with respect to supine vascular resistances.
Assessment of blood pressures and gradients by automated blood pressure device compared to invasive measurements in patients previously operated on for coarctation of the aorta
Authors: Wendel H. , Teien D. , Human D. G. , Nanton M. A.
Published: April 2008

Summary. The aim of the study was to compare invasive and non‐invasive blood pressure measurements and gradients. Twenty‐two children and 16 adults previously operated for coarctation of the aorta were included. Invasive blood pressures were recorded proximally and distally close to the former operation site and non‐invasive systolic blood pressures were recorded by an automated sphygmomanometer on right arm and leg. The adults were investigated at rest and during supine exercise. The correlation between invasive and non‐invasive measurements of proximal blood pressures in adults at rest and children were the following, r= 0.92, SD 7.6 mmHg (n= 16) and r= 0.85, SD 11 mmHg (n= 22) respectively. The corresponding correlation for the distal blood pressures were the following for adults at rest 0.64, SD 11.9 mmHg and in children /‐ = 0.82, SD 9.2 mmHg.

During exercise in adults we found a low correlation when comparing invasive and non‐invasive proximal and distal blood pressures and a poor correlation regarding the gradients, r= 0.50, SD 16 mmHg, r= 0.45, SD 15.9 mmHg and r= 0.30, SD 22.9 mmHg respectively (n= 16).

We also measured the time interval between cessation of exercise and completion of the blood pressure recordings, which gave a mean interval of 73 sec (range 45–115 sec). During that interval the mean fall in the proximal blood pressure was 37 mmHg (range 20–80 mmHg), and the mean fall of the gradient was from 41 mmHg (range 20–76 mmHg) to 23 mmHg (range 6–56 mmHg).

We conclude that the non‐invasive estimation of proximal blood pressures gave fair results but that the estimation of gradients are unsatisfactory. The use of this method to predict exercise induced blood pressures changes and gradients seems highly unreliable.
Renal vein oxygen saturation in renal artery stenosis
Authors: Nielsen K. , Rehling M. , Henriksen J. H.
Published: April 2008

Summary. Renal vein oxygen‐saturation was measured in 56 patients with arterial hypertension and unilateral stenosis or occlusion of the renal artery. Oxygen‐saturation in blood from the ischaemic kidney (84.4%, range 73–93%) was significantly higher than that from the ‘normal’ contralateral kidney (81.2%, range 70–90%, P<0.001). In only six patients, the ischaemic kidney revealed a venous oxygen‐saturation below the contralateral value (mean difference ischaemic‐normal kidney 3.2%, range ‐6 to 15%). The results indicate that the oxygen uptake in the chronic ischaemic kidney is more decreased than its blood flow. This is probably due to decreased filtration fraction and filtered sodium with subsequent reduction in absolute tubular re‐absorption of sodium ions.
Plasma concentrations of atrial peptides ANF(l‐98) and ANF(99–126) after intravenous infusion: effect of infusate temperature
Authors: Hall C. , TØllØfsrud S. , Bjerkelund C.‐E. , Noddeland H. , Sundsfjord J.
Published: April 2008

Summary. Atrial peptides ANF(l‐98) and ANF(99–126) were measured in plasma before and after infusion of Ringer‐Acetate solution in healthy volunteers. The solution was infused over a 45 min period in an amount equal to 20 per cent of estimated extra‐cellular volume. We found that the increase in atrial peptide immuno‐reactivity after infusion depended on the temperature of the infusate. The molar increase in ANF(l‐98) was much larger than the increase in ANF(99–126). We speculate that plasma levels of ANF(l‐98) may be a clinically useful parameter of atrial distension secondary to hypervolaemia.
Ineffective ventilation during exercise in patients with chronic congestive heart failure
Authors: Sovijärvi A. R. A. , Näveri H. , Leinonen H.
Published: April 2008

Summary The pathophysiologic mechanisms causing exertional breathlessness in patients with chronic congestive heart failure (CHF) are not fully understood. Therefore, we have studied whether the ventilation in such patients is ineffective during exercise. Thirteen patients with treated chronic CHF (New York Heart Association class II‐IV) and eight healthy controls underwent a maximal bicycle ergometer test with continuous analysis of expired air and frequent arterial blood sampling for gas and lactate analysis. All subjects were non‐smokers and none had any signs of a pulmonary disease. Peak O2 consumption of the patients was 14.9 ±5.3 ml min‐1 kg‐1 and that of controls 33.6 ±7.5 ml min‐1 kg‐1. In patients with CHF the ratio of pulmonary dead space to tidal volume was significantly elevated at peak exercise compared with that of the controls (0.36±0.08 vs. 0.20±0.07, P<0.05). The ventilatory equivalent for CO2 (VE:VCO2) was also significantly higher in patients than in controls during exercise (P<0.05). Furthermore, both the ventilatory equivalents for CO2 and O2 (VE:VD2) had a significant inverse correlation with peak O2 consumption (P<0.001 for VE:VT:O2 and P<0.05 for VE:VO2), O2 consumption at anaerobic threshold (P<0.01) and O2‐pulse (P<0.001) among the patients. During exercise the arterial PO2 and PCO2 remained normal in patients and controls.

These data indicate that in patients with chronic CHF wasted ventilation is pathologically increased during exercise, and this is related to the severity of the disease. Chronic CHF is not associated with decreased ventilatory reserve, hypoxaemia or alveolar hyperventilation. The ineffectiveness of ventilation is probably an important cause of exertional breathlessness in patients with CHF.
Plasma endothelin‐1 during central hypovolaemia in man
Authors: Matzen S. , Emmeluth C. , Millikent M. C. , Sechert N. H.
Published: April 2008

Summary. Endothelin‐1 (ET‐1) is a potent vasoconstricting peptide with effect on resistance as well as capacitance vessels. We followed ET‐1 in arterial plasma together with heart rate (HR), central venous pressure (CVP), mean arterial pressure (MAP), and thoracic electrical impedance (TI) in seven men during central hypovolaemia induced by 50± head‐up tilt. During tilting plasma ET‐1 increased from 1.1 ±0.2 to 1.4 ± 0.3 pmol 1‐1 (mean ± SE) concomitant with an increase in total peripheral resistance (TPR) (from 15 ± 2 to 25 ± 3 mmHg min 1‐1) (P< 001), and HR (from 67 ± 2 to 94 ± 5 beats min‐1) (P<0.01) while MAP remained unchanged. CVP decreased (from 1.8±0.9 to ‐1.6±1.0 mmHg) (P<0.01) during tilting and remained unchanged during sustained tilt despite further reduction of central blood volume as recorded by TI. Presyncopal symptoms occurred after 28 ± 6 min associated with decreases in HR (to 70 ± 6 beats min‐1), MAP (from 90 ± 3 to 52 ± 4 mmHg) and TPR (to 11 ± 2 mmHg min l‐1) (P<0.01). At this time plasma ET‐1 reached its highest level of 1.6±0.3 pmol l‐1 (P<0.01). Data show that head‐up tilt is associated with increased plasma concentrations of ET‐1 which may play a role in maintaining vascular tone in situations with a reduced central blood volume.
Myocardial reperfusion in thrombolysis A 99Tcm‐Sestamibi SPECT study in patients with acute myocardial infarction
Authors: Boström P.‐Å. , Diemer H. , Freitag M. , Juhlin P. , Lilja B. , Erhardt L.
Published: April 2008

Summary. This study presents the outcome of myocardial scintigraphy performed before and after thrombolytic treatment in 16 patients with acute myocardial infarction using 99Tcm‐Sestamibi (Cardiolite®, Du Pont Scandinavia AB, Kista, Sweden).

The patients were given 99Tcm‐Sestamibi intravenously as soon as possible after the decision to give thrombolytic treatment. When the patients were in a clinically stable state after the thrombolytic treatment, myocardial perfusion was analysed with the gamma camera using single photon emission computerized tomography (SPECT). A second 99Tcm‐Sestamibi tomography was carried out on the second to fourth day after the myocardial infarction. Data reconstruction was done with the ‘Bull's eye technique’.

Nine patients received thrombolysis < 3 h from the onset of pain. In this group six patients (66%) improved their myocardial perfusion by > 10% after treatment, while all seven patients who received treatment ≥ 3 h after the onset of pain improved their myocardial perfusion by < 10%.

This study emphasises the importance of early diagnosis and treatment of patients with acute myocardial infarction in order to salvage myocardium.
Attenuated Valsalva heart rate response in subjects with smoking history: possible role of autonomic dysfunction
Authors: Piha S. J. , Seppänen A.
Published: April 2008

Summary. The effects of smoking habits on aotnomic cardiovascular heart rate reflexes were studied in 143 healthy subjects by using the Valsalva manoeuvre and deep breathing tests. Smoking seemed to cause attenuation of the Valsalva heart rate response. This attenuation was present also after adjustment for possible confounding factors including alcohol consumption. Our findings show that in subjects with smoking history there may occur dysfunction in some part of the autonomic reflex arch mediating the Valsalva heart rate response.
Variability of digitized left ventricular M‐mode echocardiography: a study in healthy subjects and patients with repaired tetralogy of Fallot
Authors: Norgård G. , Johannessen K. A.
Published: April 2008

Summary. To assess possible factors affecting the variability of digitized left ventricular M‐mode echocardiograms, the influence of respiration and the variability due to different beats and observers were analysed in 11 healthy subjects and 11 patients with repaired tetralogy of Fallot. Left ventricular end‐diastolic dimension (LVEDD) decreased from end‐expiration to end‐inspiration in the healthy subjects, but not in the patients. The maximal rate of dimension change decreased in both healthy subjects and patients from end‐expiration to end‐inspiration. The beat‐to‐beat variability assessed by the coefficient of variation (CV,%) between measurements of one cardiac cycle was twice the CV for three cycles, whereas the CV for three and five cardiac cycles was not different. The CV for intraobserver variability was less than 5.0% for dimensions and less than 13 0% for the rates of dimension change, whereas the interobserver variability had CV of 17.1% for rates of dimension changes. The influence of respiration and different observers on the variability of LV end‐systolic dimension and shortening fraction was larger in the patients than in the healthy subjects. Thus, to obtain optimal technique for analysis of digitized LV M‐mode echocardiograms in serial patient studies, the number of observers should be kept at a minimum and at least 3 beats at end‐expiration should be used.
Neuropeptide Y, noradrenaline and invasive haemodynamic data in mild to moderate chronic congestive heart failure
Authors: Ullman B. , Jensen‐Urstad M. , Hulting J. , Lundberg J. M.
Published: April 2008

Summary. Neuropeptide Y (NPY) is a peptide released together with noradrenaline (NA) from sympathetic nerve endings. Elevated plasma levels of NA and NPY‐like immunoreactivity (LI) are found in patients with congestive heart failure. In order to assess any relationship found between plasma NPY‐LI and haemodynamic data 12 patients with mild to moderate chronic congestive heart failure were studied during cardiac catheterization. All patients were treated with diuretics but not ACE inhibitors and were in New York Heart Association functional class II or III. Mean left ventricular ejection fraction determined by echocardiography was 34%. Plasma NPY‐LI from mixed venous blood was elevated in five patients and NA in nine. Mean plasma NPY‐LI was 29±3pmoll‐1(mean±standard error of the mean) and NA2.6±0.3nmoll‐1. Heart rate was 70±3 beats min‐1, systolic blood pressure (SBP) 131 ±7 mmHg, stroke volume index (SVI) 29±l.9 ml m‐2 and cardiac index (CI) 2.0±0.13 1 min‐1 m‐2. Elevated levels of plasma NPY‐LI (>30 pmol l‐1) were associated with lower SVI, CI, and SBP and a higher pulmonary vascular resistance. Elevated plasma NA (>2 nmol 1‐1) did not correlate with haemodynamic data. Log NPY‐LI correlated inversely with SVI (P < 0.01) and CI (P < 0.05) but not with plasma NA. It is concluded that log NPY‐LI in mixed venous blood correlates inversely with SVI and CI in patients with mild to moderate chronic congestive heart failure.
Simulation of the electrogram from ion currents
Authors: Wohlfart B. , Arlock P.
Published: April 2008

Summary. The electrogram can be constructed as the difference between two action potentials starting with a slight time difference. In the present study, the action potentials were simulated from ion currents showing time‐ and voltage‐dependent activation and inactivation. Simple mathematics like straight lines and single exponential functions were used. The aim was not to give a precise description of the action potential but to obtain a model with electronic interaction between action potentials. Four currents were incorporated. The upstroke of the action potential was due to the inflow of sodium ions. The plateau was maintained by a calcium current and repolarization followed from a slowly activated and outwardly directed potassium current. There was also a time‐independent background current of potassium showing inward rectification. Basically the same equations were used for calculation of the four current voltage relations. Also, currents during a depolarizing voltage step could be reproduced by the model. Two action potentials were coupled to each other by means of a resistor to simulate the behaviour of gap junctions. A flat T‐wave in the electrogram occurred when the action potentials had the same characteristics because of the electrotonic interaction. When the first action potential was longer than the second in a pair positive T‐waves were seen. A negative T‐wave occurred when the second action potential of the pair was made longer. The model forms a base for further simulations of ECG.
Volume blood flow measurements with a transit time flowmeter: an in vivo and in vitro variability and validation study
Authors: Lundell A. , Bergqvist D. , Mattsson E. , Nilsson B.
Published: April 2008

Summary. A transit time flowmeter, Transonic TC101 (Transonic Inc., USA) has been evaluated to study volume flow. Two flow probes, 4 and 6 mm, were used. The experiments were carried out in vivo on the carotid arteries (n= 16) in sheep and in vitro against a pre calibrated rotational pump. Exsanguination measurements, n= 32, were used for the calculation of the error of measurement in vivo. The error of measurement in vitro was calculated on 11 different flow rates from 0 to 150 ml min‐1.

The variability in vivo was evaluated using data from 10, 30 s measurement periods with a 30 s pause between measurements. The variability in vitro was evaluated at three flow rates (46, 78, and 113 ml min‐1). Five 1‐min measurements with a 1‐min pause between measurements were made.

The error of measurement in vivo was 12.05% and in vitro 5.50% (4 mm probe) and 14.90% (6 mm probe). In vivo the variability was between 1.1 and 4.4% and in vitro between 1.5 and 11.2%. The correlation coefficients between the flowmeter on the one hand and exsanguination and the rotational pump on the other were 0.99, 0.99 (4 mm probe) and 0.98 (6 mm probe).

It is concluded that the flowmeter has a small variability and error of measurement both in vivo and in vitro.,
DC photoplethysmography in the evaluation of sympathetic vasomotor responses
Authors: Barron S. A. , Rogowski Z. , Kanter Y. , Hemli J.
Published: April 2008

Summary. The d.c. component of the photoplethsmographic signal was used to determine the response of the finger vasculature to three standard tests of vasomotor function: (1) an inspiratory gasp (IG), (2) immersion of the contralateral hand in ice water (IW), and (3) the Valsalva maneouvre. The vasconstrictor response to the first two of these stimuli could be measured in all of 25 normal subjects. The response to the Valsalva maneouvre could not be detected consistently. Seven patients with known sympathetic autonomic dysfunction showed no response to either IG or IW. In 30 patients with diabetes mellitus of over 10 years duration, 46.7% had no response to IG, and 20% had no response to IW. Absent responses correlated with abnormal autonomic cardiovascular reflexes, with absent sympathetic skin responses and with the severity of peripheral somatic neuropathy. The d.c. photoplethysmographic determination of the vasoconstrictor response in the finger after a deep inspiratory gasp and after ice water immersion offers an additional measure of the function of small (2μ‐6μ) peripheral nerve fibres. Because of variability in the amplitude of the responses in normals, only an absent response should be accepted as abnormal.
Transperitoneal transport of creatinine. A comparison of kinetic models
Authors: Fugleberg S. , Graff J. , Joffe P. , Løkkegaard H. , Feldt‐Rasmussen B. , Fogh‐Andersen N. , Nielsen S. Levin
Published: April 2008

Summary. Six kinetic models of transperitoneal creatinine transport were formulated and validated on the basis of experimental results obtained from 23 non‐diabetic patients undergoing peritoneal dialysis. The models were designed to elucidate the presence or absence of diffusive, non‐lymphatic convective and lymphatic convective solute transport. The validation procedure included an assessment of theoretical (a priori) and practical (a posteriori) identifiability, goodness of fit, residual error analysis and plausibility of parameter estimates. The results of the validation procedure demonstrate that the model including all three forms of transport is superior to other models. We conclude that the best model of transperitoneal creatinine transport includes diffusion, non‐lymphatic convective transport and lymphatic convective transport.
Magnesium sulphate infusion decreases circulating calcitonin gene‐related peptide (CGRP) in women with primary Raynaud's phenomenon
Authors: Myrdal U. , Leppert J. , Edvinsson L. , Ekman R. , Hedner T. , Nilsson H. , Ringqvist I.
Published: April 2008

Summary. The effects of two different vasodilating agents (MgSO4 infusion and the calcium antagonist nifedipine) on circulating levels of calcitonin gene‐related peptide (CGRP) were studied in 12 women with pronounced primary Raynaud's phenomenon (PRP) and in 12 healthy females. There were no significant differences with regard to basal levels of circulating CGRP between women with PRP and the control group; median 15–5 (range 10–48) vs. 14 (range 10–69) pmol 1‐1, respectively. However, treatment with MgSO4 infusion significantly decreased circulating CGRP in women with PRP only from median 15–5 (range 10–48) to 10 (range 10–110) pmol l‐1) (P<0–05). On the other hand 14 days of treatment with nifedipine did not affect circulating CGRP in either of the investigated groups.

Erythrocyte magnesium (ery‐Mg) levels increased significantly after MgSO4 infusion in women with PRP (2–43± 0–13 vs. 2–52 ± 0–15mmol 1‐1, P<0–05) but not in the controls (2–51 ± 0–24 vs. 2–57 ± 0–28 mmol l‐1, ns).

In conclusion, the decrease of circulating CGRP after MgSO4 infusion in women with PRP provides further evidence that magnesium plays a significant role in the pathophysiology of PRP.
Effects of head‐up and head‐down tilt on the transmitral flow velocities in relation to age: a Doppler echocardiographic study in healthy persons
Authors: Voutilainen S.
Published: April 2008

Summary. To assess whether age modifies the effects of preload on the Doppler indexes of left ventricular filling, 10 younger (mean age 31 years) and 10 older (mean age 53 years) healthy subjects underwent transmitral flow velocity measurements following acute changes of venous return produced by head‐up and head‐down tilts. In the horizontal supine position, almost all Doppler indexes differed significantly between the groups. As venous return increased from the head‐up to the head‐down position, the peak early and late transmitral velocities, their ratio, and the acceleration and deceleration of the early flow increased while the relaxation time shortened. These changes did not differ significantly between the younger and older subjects. In conclusion, both age and preload have strong effects on the Doppler transmitral velocity indexes. The preload‐induced changes are not modified by age.
Diving physiology and pathophysiology
Authors: Madsen J. , Hink J. , Hyldegaard O.
Published: April 2008

Summary. Divers have worked at 500 m depth in the sea and have reached 700 m in simulated chamber dives. A prerequisite for this has been extensive physiological studies of the body's reactions to pressure and pressure changes. This paper reviews such physiological and pathophysiological studies with emphasis on recent developments.
Model for radionuclide evaluation of left‐to‐right ductal shunts
Authors: Eterovic D. , Dujic Ž. , Tocilj J. , Popovic S.
Published: April 2008

Summary. A model for radionuclide evaluation of left‐to‐right ductal shunts was designed. It was a generalization of the standard Maltz‐Treves method, accounting for the possibility that distribution of the shunt flow between the two lungs differs from that in the right ventricular (RV) output (Fs). This yields a new formulation in which the ratio of ductal flow to pulmonary flow (Fd/Fp) equals a weighted average of Fd/Fp obtained separately for the right lung (RL) and the left lung (LL), i.e. Fd/Fp= R(Fd/FpP)RL+ (1‐R) (Fd/Fp)LL; where R is the fraction of the RV output going to the right lung. Separate shunt‐flow ratios can be obtained by conventional analysis of the respective lung radiohistogram, while R can be determined from the upslopes of these curves. Formulas were derived rigorously from basic principles, so that the ultimate clinical validity of the method depends on radioangiographic assessment of R, (Fd/Fp)RL and (Fd/Fp)LL. Due to asymmetry of flows there is no true referent method for patients with ductal shunts. Therefore a simulation study, using quasi‐real data, was utilized, yielding satisfactory performances of the algorithm: (Fp/Fs)calculated= 0–92 (Fp/Fs)simulated+ 015 (r= 0–878).,
Demonstration of dilatation of peripheral airways
Authors: Lindgren S. , Larsson S. , Holgerssonr M. , Bake B.
Published: April 2008

Summary. To investigate the ability of various lung‐function tests to demonstrate dilatation of peripheral airways, ten asthmatics inhaled increasing doses of a f2‐agonist by two different and controlled techniques. Low inspiratory flow with a long post‐inspi‐ratory pause favoured peripheral deposition, and a high inspiratory flow with a short post‐inspiratory pause favoured central deposition of drug in the airways. Ordinary spirometry, maximum expiratory flow rates after breathing air as well as a helium‐oxygen mixture, a single breath N2‐test and resistance of the respiratory system were obtained before and after each of five terbutaline doses with both inhalation techniques. By using a double‐dummy technique, the study could be performed double blinded. Effects were compared at doses giving equal effects on PEF, assumed to represent equal deposition of bronchodilator and effects on central airways. At such ‘iso A PEF doses’, particularly FVC and the slope of phase III of the N2‐test improved more following the slow inhalation technique. It is concluded that changes in those tests reflect dilatation in peripheral airways in asthmatics.,
Computerized evaluation of the peripheral blood flow during maximal vasodilatation in humans using venous occlusion plethysmography
Authors: Gretzer I. , Inacio J. , Olsson A.
Published: April 2008

Summary. Forearm blood flow was studied with venous occlusion plethysmography after ischaemic exercise in 10 healthy volunteers and 10 hypertensive patients. The peak blood flow was calculated by three methods: the manual conventional graphic technique and by fitting of a tangent to the inflow curve with the help of a computer. In addition a computer‐aided derivation of an exponential curve adapted to the initial part of the inflow curve was used for the calculation of the maximal blood flow. With the two tangential techniques the peak mean blood flow values did not differ significantly and were 58 ml min‐1 100 ml‐1 tissue while the exponential derivation procedure gave in both groups about 40% higher maximal flow values. The effect of venous occlusion on the linear velocity of the brachial arterial blood flow blood was studied with Ultrasound Doppler Flowmetry. The maximal flow velocity after ischaemic exercise decreased by about 18% during 50 mmHg venous occlusion; the influence of the venous stasis was least during the first heart beats after the onset of the venous occlusion. The effect of the venous stasis was similar but less pronounced in the hypertensive patients. In conclusion, forearm blood flow during maximal vasodilatation is reduced by venous occlusion and the best estimate of the flow is obtained from the earliest part of the venous occlusion inflow curve, as indicated by the use of the computer‐aided exponential derivation technique.
Variation in plethysmographically measured limb blood flow using two study designs
Authors: Sundberg S.
Published: April 2008

Summary. Ingestion of food is known to influence peripheral blood flow. In clinical drug trials it is important to obtain values which do not fluctuate because of exogenous factors. In the study reported here, the variability of limb blood flow was assessed using two study designs: after a light standard breakfast with nothing more to eat (Day A); and after an overnight fast followed by a heavy non‐standardized lunch (Day B). Calf and forearm blood flow (BF), venous capacity (VC) and maximal venous outflow (MVO) were measured by means of strain‐gauge venous occlusion plethysmography in 10 young healthy subjects six times during a period of 8 h. The most stable values were recorded from the calf on Day A, when no statistically significant variation occurred in any of the parameters. Mean values for calf BF ranged from 3.9 to 4.3 ml min‐1 100 ml‐1 (SEM 0.3‐0.4) at the different time points on Day A. The corresponding values for VC were 3.4‐3.7 ml 100 ml‐1 (SEM 0.2‐0.3) and for MVO were 100–112 ml min‐1 100 ml‐1 (SEM 7–10). Within‐subject coefficients of variation were 13–16%. After lunch on Day B, both calf and forearm BF increased significantly, by 40–60%, as compared with prelunch values, and remained at about this level throughout the rest of the day. The corresponding postlunch increase in VC was 25‐10%, and that in MVO was 20–25%. A study design in which the subjects ate a light, standard breakfast before the start of measurements and fasted thereafter gave fairly stable plethysmographic results.
Knee extensor performance of dominant and non‐dominant limb throughout repeated isokinetic contractions, with special reference to peak torque and mean frequency of the EMG
Authors: Lindström B. , Karlsson S. , Gerdle B.
Published: April 2008

Summary. The aim of this study was to investigate whether significant differences in peak torque (PT), mean power frequency of EMG (fmean) and perceived fatigue exist between the dominant and non‐dominant knee extensors throughout repeated contractions. The present study forms part of a research project aimed at developing tests for the determination of the degree of motor control in patients with sequelae after CNS injury. A total of 22 clinically healthy subjects (14 males and eight females) took part in the investigation. The subjects performed endurance tests of the lower limbs, consisting of 100 repeated knee extensions using a Cybex dynamometer at 1.57 rad s‐1. The patterns of PT, fmean and perception of fatigue throughout the endurance test were investigated. The endurance curves of PT and fmean showed, in common with other studies, an initial steep decrease followed by a stable phase. No significant differences existed between dominant and non‐dominant knee extensors with regard to PT, fmean or perception of fatigue. The results indicate that it may be possible to use the contralateral knee extensors as an indicator of motor recovery in hemiplegia in patients with a high degree of recovery.
Comparison of some criteria for diagnosing a myocardial infarction after aorto‐coronary bypass grafting (CABG)
Authors: Backman C. , Jacobsson K. A. , Linderholm H. , Osterman G.
Published: April 2008

Summary. The incidence of myocardial infarction during a 1‐year follow‐up period after coronary bypass surgery (CABG), i.e. a recent myocardial infarction (RMI), was studied in 86 patients. Different criteria for the diagnosis of a RMI were compared. Clinical observation, including ECG and serum enzyme analysis, diagnosed RMI in 8% of patients. Specific ECG changes indicating RMI (ECGsp) occurred in 12% of cases, and if less specific ECG changes were also taken into account (ECGsp+nonsp) RMI was found in 30% of cases. Asynergy, detected by two‐plane ventriculography, indicated RMI in 24% of the patients, and was probably the most valid of the criteria examined. The differences in diagnostic accuracy of the various criteria highlight the importance of defining diagnostic criteria.
The response of skin microcirculation to hyperthermic stress in tumour patients
Authors: Ranade G. G. , Puniyani R. R. , Huilgol N. G.
Published: April 2008

Summary. Hyperthermia and its effect on tissues are topics of great interest to scientists working in the area of radiation biology and medicine. It has been shown by many workers, that blood flow in malignant tissue displays a different response to heating than that in normal tissue. Initially, the blood flow in tumour tissue is greater than that in normal tissue, and when heat is applied there is an increase in blood flow. The extent of the increase in flow with increasing temperature is greater in normal tissue than in tumour tissue. In our laboratory we studied the effect of temperature on skin blood flow. The skin overlying tumour tissue was compared with skin with no underlying abnormality in cancer patients, and with the skin in healthy control subjects. The instrument used was a Laser Doppler Perfusion Monitor, Pf3 (Perimed, Stockholm, Sweden). We found that the skin overlying tumour tissue showed higher basal perfusion than the skin at the contralateral site with no underlying abnormality. The skin above tumour tissue showed a reduced perfusion response to an increase in temperature (vascular sluggishness) compared to skin at the contralateral site and skin in healthy controls. The reduction in thermal response depends on the size of the tumour.
Cardiovascular autonomic control is disturbed in nocturnal teethgrinders
Authors: Sjöholm T. T. , Piha S. J. , Lehtinen I.
Published: April 2008

Summary. To examine the hypothesis of disturbed autonomic function, non‐invasive cardiovascular reflex tests were performed on 11 sleep bruxists in the waking state. The tests included the Valsalva manoeuvre, a deep‐breathing test, and an orthostatic test (standing up). The R‐R intervals were monitored continuously, and blood pressure was measured non‐invasively and continuously using the Finapres method. In total, 64% of bruxists showed abnormalities in at least two variables reflecting the cardiovascular autonomic function. Abnormalities were found in blood pressure regulation during the Valsalva strain, and in the immediate biphasic heart rate response during standing up, but not in the vagally mediated deep‐breathing difference. These findings suggest that bruxism is accompanied by abnormalities in autonomic function, particularly in sympathetic vasoconstrictor function.
Validity of ambulatory 24‐h oesophageal pH measurement in the diagnosis of reflux disease
Authors: Hietanen E. , Raitakari O. T. , Backman H.
Published: April 2008

Summary. The validity of 24‐h oesophageal pH recording was studied in 100 consecutive patients who had gastro‐oesophageal reflux (GER) symptoms and had indications for a 24‐h pH recording. The aim was to explore the relationship of patient symptoms, endoscopic findings and histopathological analysis of oesophageal mucosa with the findings in pH recording. Among these patients with typical GER symptoms, the multiplicity of symptoms or their nature did not differentiate them, but in all groups abnormal amounts of reflux were present, as compared with usual reference pH recording values. Yet, among these symptomatic patients, the macroscopic severity of oesophagitis and histologically defined oesophagitis were related to increased abnormality of 24‐h pH recording. The results suggest that 24‐h pH recording of the oesophagus gives a good indication of the severity of gastro‐oesophageal reflux disease and, as such, superior to patient symptoms.
Transperitoneal transport of sodium during hypertonic peritoneal dialysis
Authors: Graff J. , Fugleberg S. , Brahm J. , Fogh‐Andersen N.
Published: April 2008

Summary. The mechanisms of transperitoneal sodium transport during hypertonic peritoneal dialysis were evaluated by kinetic modelling. A total of six nested mathematical models were designed to elucidate the presence or absence of diffusive, non‐lymphatic convective and lymphatic convective solute transport. Experimental results were obtained from 26 non‐diabetic patients undergoing peritoneal dialysis. The model validation procedure demonstrated that only diffusive and non‐lymphatic convective transport mechanisms were identifiable in the transperitoneal transport of sodium. Non‐lymphatic convective sodium transport was the most important quantitative transport mechanism during the first 90 min of the dwell. Significant sodium sieving was demonstrated and explains the observation of hypernatremia in dialysis with hypertonic dialysis fluid.
Human gallbladder pressure and volume: validation of a new direct method for measurements of gallbladder pressure in patients with acute cholecystitis
Authors: Body Lars , Højgaard Liselotte , Grønvall Svend , Stage Jens G.
Published: April 2008

Summary. Increased gallbladder (GB) pressure is probably a part of the pathogenesis of acute cholecystitis, and measurements of GB pressure might therefore be of interest. The aim of this study was to validate a microtip pressure transducer for intraluminal GB pressure measurements.

In vitro precision and accuracy was within 0.2 mmHg, (SD) and 0.6±0.1 mmHg (mean±SD), respectively. Pressure rise rate was 24.8±5.5 mmHgs‐1. Zero drift was in the range 0.3±0.4 to 0.8±0.9 mmHg (mean±SD). GB pressure was investigated in 16 patients with acute cholecystitis treated with percutaneous ultrasonically guided cholecystostomy.

Basal intraluminal GB pressure was 8.9 mmHg (2.1–12.2 mmHg; n =9, open cystic duct) and 1.8 and 5.8 mmHg (n =2, closed cystic duct). There was no significant difference between two different measurements in the same patients (n =5). The pressure was significantly influenced by respiration (n =8) and the pressure seems to be higher in the sitting position than in the supine position (n =5). Cystic duct opening pressure was 10.4,11.2 and 16.8 mmHg (n =3). Pressure‐volume responses showed that the GB up to a certain volume could accommodate increases in intraluminal volume with only slight changes in intraluminal pressure (n =4).

Except for the zero drift, this piece of equipment seemed to fulfil the requirements of being able to measure pressure in the GB. In vivo measurements showed a good clinical reproducibility of the method, and also that respiration and patient posture influenced the pressure measurements. Further, a GB pressure‐volume relationship was demonstrated, and the possibility of a cystic duct opening pressure was described.
Cardiac output and blood pressure during active and passive standing
Authors: Tanaka H. , Sjöberg B. J. , Thulesius O.
Published: April 2008

Summary. The present study compared the haemodynamic pattern of active and passive standing. We used non‐invasive techniques with beat‐to‐beat evaluation of blood pressure, heart rate and stroke volume. Seven healthy subjects, aged 24–41 (mean 30) years were examined. Finger blood pressure was continuously recorded by volume clamp technique (Finapres ®), and simultaneous beat‐to‐beat beat stroke volume was obtained, using an ultrasound Doppler technique, from the product of the valvular area and the aortic flow velocity time integral in the ascending aorta from the suprasternal notch. Measurements were performed at rest, during active standing and following passive tilt (60°). Active standing caused a transient but greater reduction of blood pressure and a higher increase of heart rate than passive tilt during the first 30 s (δ mean blood pressure: ‐39 ± 10 vs. ‐16 ± 7 mmHg, δ heart rate: 35 ± 8 vs. 12 ± 7 beats m‐1 (active standing vs. passive tilt; P < 0.01). There was a significantly larger increase in cardiac output during active standing (37 ± 24 vs. 0 ± 15%, P < 0.01) and a more marked decrease in total peripheral resistance (‐58 ± 11 vs. ‐16 ± 17%, P < 0.01). A precipitous rise in intra‐abdominal pressure (43 ± 22 mmHg) could be observed upon rising only in active standing. This was interpreted as an indication of translocation of blood to the thorax. There was no significant difference in haemodynamic changes during the later stage of standing (1–7 min) between both manoeuvres. These results suggest that active standing causes a marked blood pressure reduction in the initial phase which seems to reflect systemic vasodilatation caused by activation of cardiopulmonary baroreflexes, probably due to a rapid shift of blood from the splanchnic vessels in addition to the shift from muscular vessels associated with abdominal and calf muscle contraction. Moreover, the ultrasound Doppler technique was found to be a more adequate method for rapid beat‐to‐beat evaluation of cardiac output during orthostatic manoeuvres.
Electrical restitution in diseased human ventricular myocardium
Authors: Nánási Péter P. , Varró András , Pankucsi Csaba , Homolay Péter , Knilans Timothy K. , Kovács László , Papp Gyula J. , Lathrop David A.
Published: April 2008

SUMMARY. Action potential configuration and electrical restitution were studied in diseased human ventricular muscle by comparing the characteristics of hypertrophic (HYP) and dilated (DIL) human ventricular preparations. Conventional microelectrode techniques were used to evaluate action potentials evoked at increasingly longer diastolic intervals. The steady‐state action potential duration (APD90) was significantly longer in DIL than in HYP preparations (393±5 ms, n = 4 and 296 ± 11 ms, n = 4, respectively; P < 0–001, mean ± SEM). In the dilated preparations studied at long diastolic intervals, the initial period of rapid repolarization (phase 1) was absent, and the rate of final repolarization (phase 3) was reduced. Electrical restitution relations in these preparations were fitted as the sum of two exponentials. The time constant of the fast component was significantly longer in DIL than in HYP preparations (242 ± 9 ms and 121 ± 4 ms, respectively; P < 0–001). No difference was observed in the time constants for the slow component of restitution in the two groups.

Electrical restitution was also studied in single human ventricular myocytes by using patch clamp techniques. The initial 600 ms period of restitution was fitted in these cells to a monoexponential function. The time constant for this period of the restitution relation was significantly longer, while the estimated amplitude of this early rising phase was significantly lower in human cells obtained from DIL hearts than the respective parameters obtained in the healthy canine and guinea pig cells also examined.

The observed changes in the restitution kinetics of the dilated human heart are, likely, the consequence of alterations in the ionic currents that underlie the cardiac action potential.
Plasma nitrate as an index of nitric oxide formation in man: analyses of kinetics and confounding factors
Authors: Jungersten L. , Edlund A. , Petersson A‐S. , Wennmalm Å.
Published: April 2008

SUMMARY. Nitric oxide (NO) is metabolized to nitrate in humans. Accordingly, plasma nitrate has been proposed as an index of the in vivo formation of NO. Such an application requires knowledge about the possible influence of nitrate from sources other than endogenous NO formation, as well as of the kinetics of nitrate in plasma. In the present study, plasma nitrate increased from 32 ± 4 to 205 ± 27 μmol/1 (mean ± SE) following intake of nitrate‐rich food. It dropped during the intake of nitrate‐restricted diet and stabilized at a level of 29 ± 1 μmol/1. The urinary excretion of nitrate during nitrate restriction was 840 ± 146 μmol/24 h. Plasma nitrate was not affected following the intake of a gastrointestinal antibiotic drug for a period of four days. Smoking three cigarettes in succession did not affect the plasma nitrate levels significantly. The oral intake of potassium nitrate (500 mg ± 4950 μmol) elevated plasma nitrate from 29 ± 3 to 313 ± 12 μmol/1 within 60 min. The subsequent drop in plasma nitrate, with a t1/2 of 451 ± 42 min, was probably a reflection of the redistribution of nitrate within the body fluids and the renal excretion of nitrate. The plasma clearance of nitrate was 30 ± 2 ml/min/1.73 m2 BSA. The distribution volume for nitrate was 28 ± 1% of the bodyweight (BW). We conclude that plasma nitrate can be used as an index of the endogenous formation of NO, provided that the oral intake of nitrate is restricted for at least 48 h. Due to the large distribution volume and the low clearance of the ion wide‐spread, marked, and chronic changes in NO formation are required to significantly affect the levels of nitrate in samples of mixed blood.
Comparison of hyperinsulinaemic clamp experiments using venous, ‘arterialized’ venous or capillary euglycaemia
Authors: Nauck M. A. , Blietz R. W. , Qualmann C.
Published: April 2008

SUMMARY.It has been suggested that deviations from arterial euglycaemia during hyperinsulinaemic clamp experiments that use venous plasma glucose measurements may alter the results of such tests (glucose infusion rate, C‐peptide suppression, etc.) and that ‘arterialized’ venous blood (‘heated‐hand’ technique) may be suitable to circumvent these problems. Therefore, nine normal male fasting volunteers (age 25 ± 4 years, body mass index 23‐5± 2–3 kg m‐2) were examined three times using an insulin infusion of 1 mU kg min‐1over 120 min. Glucose was infused to maintain a concentration of 4–7 mmol 1‐1(85 mg dl‐1) in venous (V), ‘arterialized’ venous (‘heated‐hand’ technique; HH), or capillary (C) plasma. The ‘heated‐hand’ technique caused a rise in (rectal) body temperature of 0–3 ± 0‐l°C (P < 0–0001). Whereas the glucose aim was reached to a similar degree in all experiments (P = 0–36), capillary glucose concentrations differed slightly, but significantly (higher in experiments with venous and ‘arterialized’ venous blood specimens; P = 0–034). There were no significant differences regarding steady‐state insulin concentrations (P = 0–77), glucose infusion rates (V, 7‐1 ± 0–5; HH, 7‐2 ± 0–6; C, 6‐4 ± 0–5 mg kg‐1min‐1; P = 0–98), C‐peptide suppression (P = 0–78), reduction in glucagon (P = 0–27) and free fatty acids (P = 0–16), and all parameters of indirect calorimetry (non‐protein RQ: P = 0–67; glucose and lipid oxidation: P = 0–72 and 0–46 respectively; and energy expenditure: P = 0–42). Therefore, hyperinsulinaemic clamp experiments performed using venous, ‘arterialized’ venous, or capillary euglycaemia appear to be almost equally useful for the determination of insulin sensitivity and C‐peptide or glucagon suppression. The elevation in body temperature that accompanies use of the ‘heated‐hand’ technique does not noticeably influence measured metabolic parameters.
Explaining National Border Effects in the QUAD Food Trade
Authors: Olper Alessandro , Raimondi Valentina
Published: April 2008

Using a ‘structural’ gravity‐like model, this paper first provides estimates of bilateral ‘border effects’ in food trade among the QUAD countries (the US, Canada, Japan and the EU) at the ISIC (International Standard Industrial Classification) four‐digit level (18 food sectors). It then investigates the underlying reasons for border effect, assessing the role played by policy barriers (tariffs, non‐tariff barriers to trade (NTBs) and domestic support) with respect to barriers unrelated to trade policy, such as information‐related costs, cultural proximity and preferences. In contrast to several previous findings, our results show that policy trade barriers, especially in the form of NTBs, are part of the story in explaining national border effects. Interestingly, in all country pair combinations, NTBs significantly dominate the trade reduction effect induced by tariffs. However, results show that elements linked to information‐related costs and consumer preferences matter a great deal in explaining the magnitude of border effects. These findings have implications for the economic and welfare‐related significance of national borders.